343 results on '"Gabriel, L."'
Search Results
2. Proteomic Characterization of a 3D HER2+ Breast Cancer Model Reveals the Role of Mitochondrial Complex I in Acquired Resistance to Trastuzumab
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Ivana J. Tapia, Davide Perico, Virginia J. Wolos, Marcela S. Villaverde, Marianela Abrigo, Dario Di Silvestre, Pierluigi Mauri, Antonella De Palma, and Gabriel L. Fiszman
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HER2+ breast cancer ,Trastuzumab resistance ,3D cell culture ,proteomics ,systems biology ,mitochondria ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
HER2-targeted therapies, such as Trastuzumab (Tz), have significantly improved the clinical outcomes for patients with HER2+ breast cancer (BC). However, treatment resistance remains a major obstacle. To elucidate functional and metabolic changes associated with acquired resistance, we characterized protein profiles of BC Tz-responder spheroids (RSs) and non-responder spheroids (nRSs) by a proteomic approach. Three-dimensional cultures were generated from the HER2+ human mammary adenocarcinoma cell line BT-474 and a derived resistant cell line. Before and after a 15-day Tz treatment, samples of each condition were collected and analyzed by liquid chromatography–mass spectrometry. The analysis of differentially expressed proteins exhibited the deregulation of energetic metabolism and mitochondrial pathways. A down-regulation of carbohydrate metabolism and up-regulation of mitochondria organization proteins, the tricarboxylic acid cycle, and oxidative phosphorylation, were observed in nRSs. Of note, Complex I-related proteins were increased in this condition and the inhibition by metformin highlighted that their activity is necessary for nRS survival. Furthermore, a correlation analysis showed that overexpression of Complex I proteins NDUFA10 and NDUFS2 was associated with high clinical risk and worse survival for HER2+ BC patients. In conclusion, the non-responder phenotype identified here provides a signature of proteins and related pathways that could lead to therapeutic biomarker investigation.
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- 2024
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3. A Fresh Look at the Potential of Cyclodextrins for Improving the Delivery of siRNA Encapsulated in Liposome Nanocarriers
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Betzaida Castillo Cruz, Marienid Flores Colón, Robert J. Rabelo Fernandez, Pablo E. Vivas-Mejia, and Gabriel L. Barletta
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Chemistry ,QD1-999 - Published
- 2022
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4. Can CP Be Less Than CV?
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Yingbin Ge, Samuel L. Montgomery, and Gabriel L. Borrello
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Chemistry ,QD1-999 - Published
- 2021
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5. Biological Hydrogen Production by Dark Fermentation in a Stirred Tank Reactor and Its Correlation with the pH Time Evolution
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Verónica L. Martínez, Gabriel L. Salierno, Rodrigo E. García, María José Lavorante, Miguel A. Galvagno, and Miryan C. Cassanello
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biohydrogen ,dark fermentation ,pH influence ,Gompertz model ,Chemical technology ,TP1-1185 ,Chemistry ,QD1-999 - Abstract
Dark fermentation is a hydrogen generating process carried out by anaerobic spore-forming bacteria that metabolize carbon sources producing gas and short-chain acids. The process can be controlled, and the hydrogen harvested if bacteria are grown in a reactor with favorable conditions. In this work, bacteria selected from natural sources were grown with a defined culture media, while pH was monitored, with the aim of relating the amount of generated hydrogen to the increase in hydron ion concentration. Therefore, a model based on the acid-base species mass balance is proposed and solved to estimate the lag phase time and measure the hydrogen production efficiency and kinetics. Hydrogen production in a stirred batch reactor was performed for 150–200 h, at given operating conditions using a previously defined growth media, to validate the model. Using the proposed model, the cumulated moles of produced hydrogen correlate well with those predicted from the pH curve. Hence, the modified Gompertz model parameters, largely used for describing the hydrogen generation kinetics by dark fermentation, were estimated from the pH curve and from the experimentally measured generated hydrogen. Satisfactory agreement was found, thus, validating the method.
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- 2022
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6. Functionalization with Polyphenols of a Nano-Textured Ti Surface through a High–Amino Acid Medium: A Chemical–Physical and Biological Characterization
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Rafaella C. P. Scannavino, Giacomo Riccucci, Sara Ferraris, Gabriel L. C. Duarte, Paulo T. de Oliveira, and Silvia Spriano
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titanium ,functionalization ,polyphenols ,implants ,Chemistry ,QD1-999 - Abstract
The study aimed to identify an effective mechanism of adsorption of polyphenols on a nano-textured Ti surface and to evaluate the osteogenic differentiation on it. The source of polyphenols was a natural extract from red grape pomace. A chemical etching was used to form an oxide layer with a nanoscale texture on Ti; this layer is hydrophilic, but without hydroxyl groups with high acidic–basic chemical reactivity. The samples were characterized by electron and fluorescence microscopies, UV–Vis spectroscopy, contact angle measurements, zeta potential titration curves, and Folin–Ciocâlteu test. The presence of an adsorbed layer of polyphenols on the functionalized surface, maintaining redox ability, was confirmed by several tests. Consistent with the surface features, the adsorption was maximized by dissolving the extract in a high–amino acid medium, with respect to an inorganic solution, exploiting the high affinity of amino acids for polyphenols and for porous titanium surfaces. The osteogenic differentiation was assessed on an osteoblastic cell line by immunofluorescence, cell viability, expression of key osteoblast markers, and extracellular matrix mineralization. The surfaces functionalized with the extract diluted in the range 1 × 10−5–1 mg/mL resulted in having a greater osteogenic activity for the highest concentration, with lower values of cell viability; higher expression of alkaline phosphatase, bone sialoprotein, and collagen; and lower levels of osteopontin. In conclusion, the functionalization of a nano-textured Ti surface with polyphenols can potentially favor the osteogenic activity of osseointegrated implants.
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- 2022
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7. [Ag(L)NO3] Complexes with 2‑Benzoylpyridine-Derived Hydrazones: Cytotoxic Activity and Interaction with Biomolecules
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Ane F. Santos, Isabella P. Ferreira, Carlos B. Pinheiro, Verlane G. Santos, Miriam T. P. Lopes, Letícia R. Teixeira, Willian R. Rocha, Gabriel L. S. Rodrigues, and Heloisa Beraldo
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Chemistry ,QD1-999 - Published
- 2018
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8. Fungal dual-domain LysM effectors undergo chitin-induced intermolecular, and not intramolecular, dimerization
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Hui Tian, Jeroen R. Mesters, Bart P. H. J. Thomma, Anja Kombrink, and Gabriel L. Fiorin
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Physiology ,Plant Immunity ,Chitin ,Plant Science ,Fungal Proteins ,chemistry.chemical_compound ,Solanum lycopersicum ,Chitin binding ,Genetics ,Life Science ,Secretion ,MAMP ,Colletotrichum higginsianum ,Plant Diseases ,biology ,Effector ,Chemistry ,fungi ,Pattern recognition receptor ,food and beverages ,biology.organism_classification ,Cell biology ,Laboratorium voor Phytopathologie ,Laboratory of Phytopathology ,EPS ,Dimerization - Abstract
SUMMARYChitin is a homopolymer of β-(1,4)-linked N-acetyl-D-glucosamine (GlcNAc) and a major structural component of fungal cell walls. In plants, chitin acts as a microbe-associated molecular pattern (MAMP) that is recognized by lysin motif (LysM)-containing plant cell surface-localized pattern recognition receptors (PRRs) that activate a plethora of downstream immune responses. In order to deregulate chitin-induced plant immunity and successfully establish infection, many fungal pathogens secrete LysM domain-containing effector proteins during host colonization. It was previously shown that the LysM effector Ecp6 from the tomato leaf mould fungus Cladosporium fulvum can outcompete plant PRRs for chitin binding because two of its three LysM domains cooperate to form a composite groove with ultra-high (pM) chitin-binding affinity. However, most functionally characterized LysM effectors contain only two LysMs, including Magnaporthe oryzae MoSlp1, Verticillium dahliae Vd2LysM, and Colletotrichum higginsianum ChElp1 and ChElp2. Here, we performed modelling, structural and functional analyses to investigate whether such dual-domain LysM effectors can also form ultra-high chitin-binding affinity grooves through intramolecular LysM dimerization. However, our study suggests that intramolecular LysM dimerization does not occur. Rather, our data support the occurrence of intermolecular LysM dimerization for these effectors, associated with a significantly lower chitin binding affinity than monitored for Ecp6. Interestingly, the intermolecular LysM dimerization allows for the formation of polymeric complexes in the presence of chitin. Possibly, such polymers may precipitate at infection sites in order to eliminate chitin oligomers, and thus suppress the activation of chitin-induced plant immunity.
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- 2022
9. Progress of the Catalytic Deactivation of H‐ZSM‐5 Zeolite in Glycerol Dehydration
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María Eugenia Sad, Leandro Martins, Gabriel L. Catuzo, Cristina L. Padró, Luiz G. Possato, Universidade Estadual Paulista (UNESP), and UNL – Universidad Nacional del Litoral
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Glycerol ,Dehydration ,Chemistry ,Organic Chemistry ,Deactivation ,Coke ,Glycerol dehydration ,medicine.disease ,ZSM-5 zeolite ,Catalysis ,Acid catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,medicine ,Organic chemistry ,Physical and Theoretical Chemistry - Abstract
Made available in DSpace on 2022-04-28T19:43:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Glycerol conversion into value-added chemicals has received much attention due to the prospect of increasing the biodiesel industry‘s profitability. The dehydration of glycerol is one of the most explored reactions in the valorization of glycerol, and the zeolite H-ZSM-5 is one of the furthermost used structures. In this study, several characterization techniques were used to investigate the detailed aging of coke in spent H-ZSM-5 zeolites after their use in the gas-phase glycerol dehydration to produce acrolein. The carbonaceous deposits formed almost totally in the first minutes of the reaction. They rapidly got trapped inside the pores, hampering the accessibility to active sites and the zeolite‘s full catalytic action. Two types of coke were formed during the reaction: polyglycols, on the external surface, and aromatics, inside the pores, representing the majority (∼98 wt.%) of the carbonaceous compounds. Besides, aromatic compounds age over time, becoming bulkier and more deficient in hydrogen. We also found a correlation between the amount of coke, its size, accessibility to the acid active sites, and changes in crystallographic parameters of the zeolite with the presence of coke. Instituto de Química UNESP – Universidade Estadual Paulista, Prof. Francisco Degni 55 Facultad de Ingeniería Química UNL – Universidad Nacional del Litoral, Santiago del Estero 2829 Instituto de Química UNESP – Universidade Estadual Paulista, Prof. Francisco Degni 55
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- 2021
10. Chalcogenylation of Naphthalene Derivatives Catalyzed by Iron(III) Chloride and Potassium Iodide
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Gabriel L. Silvério, Ronny R. Ribeiro, Diego Seckler, Breidi Albach, Daniel S. Rampon, Gul Badshah, Emerson A. Abreu, Eduardo Q. Luz, and David B. Lima
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010405 organic chemistry ,Chemistry ,Organic Chemistry ,Inorganic chemistry ,chemistry.chemical_element ,010402 general chemistry ,Iodine ,01 natural sciences ,Redox ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Iron(III) chloride ,Naphthalene - Abstract
We have developed an efficient chalcogenylation of electron-rich naphthalene derivatives catalyzed by FeCl3 and KI. The methodology provides access to several nonsymmetrical diorganoyl chalcogenides (S, Se) by selective C1 chalcogenylation of 2-naphthols or 2-naphthylamines using simple and cheap catalysts. Several control experiments supported the hypothesis that a redox reaction between Fe(III) and KI produces I2, which catalyzed the chalcogenylation.
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- 2021
11. One‐Pot Synthesis of 3‐Halo‐2‐organochalcogenylbenzo[ b ]chalcogenophenes from 1‐(2,2‐Dibromovinyl)‐2‐organochalcogenylbenzenes
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Daniel S. Rampon, Eduardo Q. Luz, Caroline da Ros Montes D'Oca, Ronilson Vasconcelos Barbosa, David B. Lima, Diego Seckler, Gabriel L. Silvério, and Francielli S. Santana
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Chemistry ,One-pot synthesis ,Organic chemistry ,General Chemistry ,Halo - Published
- 2021
12. Benchmarking Antioxidant-Related Properties for Gallic Acid through the Use of DFT, MP2, CCSD, and CCSD(T) Approaches
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Kirk A. Peterson and Gabriel L. C. de Souza
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Antioxidant ,010304 chemical physics ,Chemistry ,medicine.medical_treatment ,010402 general chemistry ,01 natural sciences ,Dissociation (chemistry) ,0104 chemical sciences ,chemistry.chemical_compound ,Computational chemistry ,Polyphenol ,0103 physical sciences ,medicine ,Gallic acid ,Physical and Theoretical Chemistry ,Ionization energy - Abstract
We present a benchmark investigation on the O-H bond dissociation enthalpies (BDEs) and ionization potential (IP) for gallic acid (GA), a widely known polyphenolic antioxidant. These properties were determined in the gas-phase and in water through the use of density functional theory (DFT), second-order Møller-Plesset perturbation theory (MP2), coupled-cluster with single and double excitations (CCSD), and coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)). The 6-311++G(df,p), cc-pVDZ, aug-cc-pVDZ, cc-pVTZ, and aug-cc-pVTZ basis sets were used. Regarding DFT functionals, the M06-2X provided the best agreement for the BDEs when compared to the corresponding CCSD(T)/aug-cc-pVTZ results; M06-2X was also found to be the most suitable for probing the IP for the protonated forms of GA while LC-ωPBE was the most reliable in the case of deprotonated GA. Given that these properties represent important descriptors for examining mechanisms related to the antioxidant potential of a given polyphenol, we hope that the present work can serve as a guide for computational chemists venturing in the field.
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- 2021
13. The first actinide polyiodate: a complex multifunctional compound with promising X-ray luminescence properties and proton conductivity
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Yumin Wang, Yaxing Wang, Shuao Wang, Evgeny V. Alekseev, Gabriel L. Murphy, and Philip Kegler
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Scintillation ,Materials science ,Proton ,Metals and Alloys ,General Chemistry ,Actinide ,Conductivity ,Thermal conduction ,Evaporation (deposition) ,Catalysis ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Nitric acid ,ddc:540 ,Materials Chemistry ,Ceramics and Composites ,Physical chemistry ,Luminescence - Abstract
Herein we report the first example of an actinide polyiodate compound, namely K4[(UO2)2(IO3)6(I4O11)]·(HIO3)4(H2O)6 (UPI-1), which was obtained from slow evaporation of nitric acid with a high I/U ratio. Spectroscopic measurements indicate that UPI-1 possesses X-ray luminescence properties applicable for X-ray scintillation and also exhibits modest protonic conduction.
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- 2021
14. The Potential of Flavonoids and Tannins from Medicinal Plants as Anticancer Agents
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Oana Ungureanu, Florentina Gatea, Gabriel L. Radu, and Eugenia Dumitra Teodor
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Drug ,Cancer Research ,media_common.quotation_subject ,03 medical and health sciences ,0302 clinical medicine ,In vivo ,Neoplasms ,medicine ,Humans ,Medicinal plants ,Cytotoxicity ,Cell Proliferation ,030304 developmental biology ,media_common ,Flavonoids ,Pharmacology ,0303 health sciences ,Plants, Medicinal ,Cancer prevention ,Molecular Structure ,Traditional medicine ,Plant Extracts ,Chemistry ,food and beverages ,Antineoplastic Agents, Phytogenic ,Bioavailability ,Mechanism of action ,Polyphenol ,030220 oncology & carcinogenesis ,Molecular Medicine ,Drug Screening Assays, Antitumor ,medicine.symptom ,Tannins - Abstract
The tendency of using herbs extracts or natural compounds extracted from herbs for preventing or treating different illnesses, including cancer, continues to be an alternative to drug use. Many studies of plant compounds aimed at finding substances with selective cytotoxicity on abnormal cells. Phenolic compounds, as important secondary metabolites from plants, are one of them. In this review, the recent literature data from the past five years about anticancer/antitumor effect of flavonoids and tannins extracted from medicinal plants are surveyed. The cytostatic/antitumor effects of the individual compounds extracted from plants and/or of the plants' polyphenolic extracts are considered, in order to point out the most significant constituents or plants with anticancer potential. The most important results concerning these compounds and their derivatives in cancer prevention and treatment, the importance of their chemical structure, their mechanism of action in vitro and in vivo, and some bioavailability aspects are discussed.
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- 2020
15. Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Based on Melting of the Donor Phase: a New Approach for the Determination of Trace Elements in Solid Samples
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Jorge S. Almeida, Gabriel L. Santos, Lucilia A. Meira, Ana Carla de Souza Nascimento, Leonardo S. G. Teixeira, and Valfredo Azevedo Lemos
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Detection limit ,Materials science ,Sonication ,Aqueous two-phase system ,Analytical chemistry ,Applied Microbiology and Biotechnology ,Analytical Chemistry ,law.invention ,chemistry.chemical_compound ,chemistry ,Nitric acid ,law ,Inductively coupled plasma atomic emission spectroscopy ,Melting point ,Inductively coupled plasma ,Safety, Risk, Reliability and Quality ,Atomic absorption spectroscopy ,Safety Research ,Food Science - Abstract
A novel ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) based on melting of the donor phase for the determination of Cd, Cu, and Fe in margarine samples using high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ET AAS) is proposed. Considering that margarine is in the solid phase at room temperature, requiring heat for melting, the microextraction process was assisted by an ultrasonic bath to ensure the melting point of the samples and to increase the extraction efficiency of the analytes by UA-DLLME. After the extraction procedure, the aqueous phase was collected and directly introduced into a graphite furnace. The procedure was applied for extraction and multi-element determination, exploring the strategy of simultaneous and sequential determination of analytes by HR-CS ET AAS. A low volume of nitric acid solution in the presence of ethanol and hydrogen peroxide allowed the metals to be separated from the sample in an aqueous phase with subsequent determination by HR-CS ETAAS. In the extraction procedure, 5.0 g of each margarine sample was sonicated under heating in the presence of 100 μL of a solution containing HNO3 0.1 mol L−1, ethanol (95.1%, v v−1), and H2O2 3% (v v−1) in a volume proportion of 2:1:1. The influences of the time of extraction, temperature of extraction, and amplitude of sonication were examined, and the proposed conditions were as follows: extraction time, 10 min; temperature, 60 °C; and amplitude, 100%. Using 5 g of margarine sample, limits of detection of 0.03, 0.52, and 224 ng g−1 were obtained for Cd, Cu, and Fe, respectively. Recovery tests were performed, and the results ranged from 87 to 108% for Cd, 91 to 115% for Cu, and 85 to 112% for Fe. The results obtained by the proposed extraction procedure agreed with those obtained after wet digestion of the sample and determination by inductively coupled plasma optical emission spectrometry (ICP OES).
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- 2020
16. Management of Adverse Events Associated with Cabozantinib Treatment in Patients with Advanced Hepatocellular Carcinoma
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Julianne O Darling, Malori Mindo, Gabriel L. Schwartz, and Lucia Damicis
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Male ,0301 basic medicine ,Sorafenib ,Oncology ,Cancer Research ,medicine.medical_specialty ,Carcinoma, Hepatocellular ,Cabozantinib ,Pyridines ,Placebo ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Quality of life ,Internal medicine ,medicine ,Humans ,Anilides ,Pharmacology (medical) ,Adverse effect ,business.industry ,Liver Neoplasms ,Therapy in Practice ,Receptor Protein-Tyrosine Kinases ,medicine.disease ,Discontinuation ,030104 developmental biology ,Tolerability ,chemistry ,030220 oncology & carcinogenesis ,Hepatocellular carcinoma ,Quality of Life ,Female ,business ,medicine.drug - Abstract
Cabozantinib is an oral multikinase inhibitor whose targets include vascular endothelial growth factor receptors, MET, and the TAM family of kinases (TYRO3, AXL, MER). Cabozantinib is approved for patients with advanced hepatocellular carcinoma who have been previously treated with sorafenib, based on improved overall survival and progression-free survival relative to placebo in the phase III CELESTIAL study. During CELESTIAL, the most common adverse events (AEs) experienced by patients receiving cabozantinib included palmar-plantar erythrodysesthesia, fatigue, gastrointestinal-related events, and hypertension. These AEs can significantly impact treatment tolerability and patient quality of life. However, AEs can be effectively managed with supportive care and dose modifications. During CELESTIAL, more than half of the patients receiving cabozantinib required a dose reduction, while the rate of treatment discontinuation due to AEs was low. Here, we review the safety profile of cabozantinib and provide guidance on the prevention and management of the more common AEs, based on current evidence from the literature as well as our clinical experience. We consider the specific challenges faced by clinicians in treating this patient population and discuss factors that may affect exposure and tolerability to cabozantinib. Electronic supplementary material The online version of this article (10.1007/s11523-020-00736-8) contains supplementary material, which is available to authorized users.
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- 2020
17. Experimental and theoretical investigation on corrosion inhibition of hexamethylenetetramine [HMT] for mild steel in acidic solution
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A. S. Ogunbadejo, Sunday J. Olusegun, Peter Apata Olubambi, Nelcy D. S. Mohallem, B. Igbaroola, A.T. Alo, Willian R. Rocha, Gabriel L. S. Rodrigues, and S. Aribo
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Langmuir ,Materials science ,General Chemical Engineering ,Inorganic chemistry ,technology, industry, and agriculture ,Hydrochloric acid ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Corrosion ,Gibbs free energy ,chemistry.chemical_compound ,symbols.namesake ,Adsorption ,Physisorption ,chemistry ,symbols ,Gravimetric analysis ,Hexamethylenetetramine ,0210 nano-technology - Abstract
This paper employs gravimetric, potentiodynamic polarization and SEM methods to study the corrosion inhibition of mild steel in 1 M solution of hydrochloric acid using hexamethylenetetramine as an inhibitor. The results show that inhibition efficiency increases with concentration up to 86% at 0.8 g L−1 inhibitor dosage. The data obtain are consistent with the isotherm proposed by Langmuir. The values of both activation and Gibbs free energy show that adsorption is physisorption and spontaneous. DFT quantum calculations also support a physisorption process which validates that nitrogen atoms are the most reactive and nucleophilic atoms, which is consistent with the experimental results.
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- 2020
18. Synthesis and characterization of aluminum citrate compounds and evaluation of their influence on the formation of hydrogels based on polyacrylamide
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Felipe Gabriel L. das Dores, Assis K. Fraga, Izabel C.V.M. Santos, Lucas G. Pedroni, Claudia R. E. Mansur, and Priscila F. Oliveira
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Materials science ,Polymers and Plastics ,Hydrogen ,Scanning electron microscope ,General Chemical Engineering ,Polyacrylamide ,technology, industry, and agriculture ,chemistry.chemical_element ,Infrared spectroscopy ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,complex mixtures ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Elemental analysis ,Self-healing hydrogels ,Materials Chemistry ,Fourier transform infrared spectroscopy ,0210 nano-technology ,Carbon ,Nuclear chemistry - Abstract
Aluminum citrate is used as a conformance control agent to improve oil production and excess water production. This paper discusses the formation of mono and polynuclear aluminum species from the synthesis of aluminum citrate and evaluates these compounds as crosslinkers in hydrogels for conformance control. The products obtained from the synthesis were characterized by Fourier-transform infrared spectrometry (FTIR), elemental analysis (CHN), scanning electron microscopy (SEM), and inductively coupled plasma–optical emission spectrometry (ICP-OES). The FTIR analyses indicated the presence of mononuclear aluminum citrate complexes at pH 3 and polynuclear species starting at pH 4. These results were corroborated by CHN and ICP-OES techniques, which revealed the variation of carbon, oxygen, hydrogen, and alumina precipitate levels as functions of pH variation. The focus of the study was to assess how these crosslinking agents perform in hydrogel formation under reservoir conditions. Rheological analysis showed that the values of tan (delta) of the hydrogel synthesized with aluminum citrate at pH 6 were lower than 0.1, indicating strong gels, while at pH 9, the values were above 0.1, indicating weak gels. These results are in agreement with those obtained by FTIR, which showed that at pH 6, the structures of the aluminum citrate complex were probably in the form [Al3(C6H5O7)3(OH)4(H2O)]4−. This structure appears to allow easier access to the aluminum orbital for the crosslinking process compared to the gel composed of aluminum citrate synthesized at pH 9 [Al3(C6H6O7)3(OH)4(H2O)5]4−.
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- 2020
19. Revisiting the Tropospheric OH-Initiated Unimolecular Decomposition of Chlorpyrifos and Chlorpyrifos-Methyl: A Theoretical Perspective
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Gabriel L. S. Rodrigues, Willian R. Rocha, Marcelo A. Chagas, and Mateus M. Quintano
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Troposphere ,chemistry.chemical_compound ,Chemistry ,Computational chemistry ,Reaction step ,Chlorpyrifos ,Chlorpyrifos-methyl ,Density functional theory ,Electronic structure ,Physical and Theoretical Chemistry ,Nuclear Experiment ,Dispersion (chemistry) ,Decomposition - Abstract
Based on density functional theory (DFT) electronic structure calculations with dispersion correction, we propose new reaction pathways in which no extra reaction step is necessary to account for the formation of 3,5,6-trichloro-2-pyridynol (TCP) within the process of tropospheric OH-initiated unimolecular decomposition of chlorpyrifos (CLP) and chlorpyrifos-methyl (CLPM). Chlorpyrifos and its analogous compound are among the most used organophosphorus pesticides worldwide, and their unimolecular decomposition in the troposphere is a dominant process of removal in the gas phase. The reaction pathways that we put forward have turned out to be the most exergonic ones among the three possible routes for the attack of the hydroxyl radical to the thiophosphoryl (P═S) bond of both CLP and CLPM. The results showed that the reaction is thermodynamically controlled with the formation of P-bonded adducts via a six-membered ring. The unimolecular decomposition of such reactive intermediates takes place with small energy barriers (less than 3 kcal mol
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- 2020
20. Non-physiologic Bioreactor Processing Conditions for Heart Valve Tissue Engineering
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Arghya Paul, Richard A. Hopkins, Mitchell C. VeDepo, Eric E. Buse, and Gabriel L. Converse
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0206 medical engineering ,Biomedical Engineering ,02 engineering and technology ,030204 cardiovascular system & hematology ,Tissue Culture Techniques ,03 medical and health sciences ,Tissue culture ,Bioreactors ,0302 clinical medicine ,Tissue engineering ,Pressure ,Bioreactor ,medicine ,Animals ,Humans ,Heart valve ,Cells, Cultured ,Sheep, Domestic ,Bioprosthesis ,Decellularization ,Tissue Engineering ,Chemistry ,Mesenchymal stem cell ,Mesenchymal Stem Cells ,Hypoxia (medical) ,medicine.disease ,020601 biomedical engineering ,Cell Hypoxia ,Extracellular Matrix ,Cell biology ,Cellular infiltration ,Phenotype ,medicine.anatomical_structure ,Aortic Valve ,Heart Valve Prosthesis ,medicine.symptom ,Cardiology and Cardiovascular Medicine - Abstract
Conventional methods of seeding decellularized heart valves for heart valve tissue engineering have led to inconsistent results in interstitial cellular repopulation, particularly of the distal valve leaflet, and notably distinct from documented re-endothelialization. The use of bioreactor conditioning mimicking physiologic parameters has been well explored but cellular infiltration remains challenging. Non-characteristic, non-physiologic conditioning parameters within a bioreactor, such as hypoxia and cyclic chamber pressure, may be used to increase the cellular infiltration leading to increased recellularization. To investigate the effects of novel and perhaps non-intuitive bioreactor conditioning parameters, ovine aortic heart valves were seeded with mesenchymal stem cells and cultured in one of four environments: hypoxia and high cyclic pressures (120 mmHg), normoxia and high cyclic pressures, hypoxia and negative cyclic pressures (− 20 mmHg), and normoxia and negative cyclic pressures. Analysis included measurements of cellular density, cell phenotype, and biochemical concentrations. The results revealed that the bioreactor conditioning parameters influenced the degree of recellularization. Groups that implemented hypoxic conditioning exhibited increased cellular infiltration into the valve leaflet tissue compared to normoxic conditioning, while pressure conditioning did not have a significant effect of recellularization. Protein expression across all groups was similar, exhibiting a stem cell and valve interstitial cell phenotype. Biochemical analysis of the extracellular matrix was similar between all groups. These results suggest the use of non-physiologic bioreactor conditioning parameters can increase in vitro recellularization of tissue engineered heart valve leaflets. Particularly, hypoxic culture was found to increase the cellular infiltration. Therefore, bioreactor conditioning of tissue engineered constructs need not always mimic physiologic conditions, and it is worth investigating novel or uncharacteristic culture conditions as they may benefit aspects of tissue culture.
- Published
- 2019
21. Correction to [Ag(L)NO3] Complexes with 2‑Benzoylpyridine-Derived Hydrazones: Cytotoxic Activity and Interaction with Biomolecules
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Ane F. Santos, Isabella P. Ferreira, Carlos B. Pinheiro, Verlane G. Santos, Miriam T. P. Lopes, Letícia R. Teixeira, Willian R. Rocha, Gabriel L. S. Rodrigues, and Heloisa Beraldo
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Chemistry ,QD1-999 - Published
- 2018
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22. Unpicking the Roles of DNA Damage Protein Kinases in Trypanosomatids
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Gabriel L. A. Silva, Richard McCulloch, Jennifer Ann Black, and Luiz R. O. Tosi
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protein kinases ,QH301-705.5 ,DNA damage ,Kinase ,DNA repair ,Mini Review ,DNA replication ,trypanosomatids ,Computational biology ,Cell Biology ,Biology ,kinetoplastids ,Cell and Developmental Biology ,chemistry.chemical_compound ,chemistry ,Transcription (biology) ,PIKK ,Biology (General) ,Protein kinase A ,DNA ,Nucleotide excision repair ,Developmental Biology - Abstract
To preserve genome integrity when faced with DNA lesions, cells activate and coordinate a multitude of DNA repair pathways to ensure timely error correction or tolerance, collectively called the DNA damage response (DDR). These interconnecting damage response pathways are molecular signal relays, with protein kinases (PKs) at the pinnacle. Focused efforts in model eukaryotes have revealed intricate aspects of DNA repair PK function, including how they direct DDR pathways and how repair reactions connect to wider cellular processes, including DNA replication and transcription. The Kinetoplastidae, including many parasites like Trypanosoma spp. and Leishmania spp. (causative agents of debilitating, neglected tropical infections), exhibit peculiarities in several core biological processes, including the predominance of multigenic transcription and the streamlining or repurposing of DNA repair pathways, such as the loss of non-homologous end joining and novel operation of nucleotide excision repair (NER). Very recent studies have implicated ATR and ATM kinases in the DDR of kinetoplastid parasites, whereas DNA-dependent protein kinase (DNA-PKcs) displays uncertain conservation, questioning what functions it fulfills. The wide range of genetic manipulation approaches in these organisms presents an opportunity to investigate DNA repair kinase roles in kinetoplastids and to ask if further kinases are involved. Furthermore, the availability of kinase inhibitory compounds, targeting numerous eukaryotic PKs, could allow us to test the suitability of DNA repair PKs as novel chemotherapeutic targets. Here, we will review recent advances in the study of trypanosomatid DNA repair kinases.
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- 2021
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23. Phase Analysis of Australian Uranium Ore Concentrates Determined by Variable Temperature Synchrotron Powder X-ray Diffraction
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Elizabeth Keegan, Rachel S. Popelka-Filcoff, Gabriel L. Murphy, Helen E. A. Brand, Allan Pring, Samantha Pandelus, and Brendan J. Kennedy
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Diffraction ,Phase transition ,Chemistry ,Rietveld refinement ,Analytical chemistry ,chemistry.chemical_element ,Uranium ,Synchrotron ,Corrosion ,law.invention ,Inorganic Chemistry ,Uranium ore ,law ,X-ray crystallography ,ddc:540 ,Physical and Theoretical Chemistry - Abstract
The chemical speciation of uranium oxides is sensitive to the provenance of the samples and their storage conditions. Here, we use diffraction methods to characterize the phases found in three aged (>10 years) uranium ore concentrates of different origins as well as in situ analysis of the thermally induced structural transitions of these materials. The structures of the crystalline phases found in the three samples have been refined, using high-resolution synchrotron X-ray diffraction data. Rietveld analysis of the samples from the Olympic Dam and Ranger uranium mines has revealed the presence of crystalline α-UO2(OH)2, together with metaschoepite (UO2)4O(OH)6·5H2O, in the aged U3O8 samples, and it is speculated that this forms as a consequence of the corrosion of U3O8 in the presence of metaschoepite. The third sample, from the Beverley uranium mine, contains the peroxide [UO2(η2-O2)(H2O)2] (metastudtite) together with α-UO2(OH)2 and metaschoepite. A core-shell model is proposed to account for the broadening of the diffraction peaks of the U3O8 evident in the samples.
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- 2021
24. The adenosine 2a receptor and TIM3 directly inhibit killing of tumor cells by cytotoxic T lymphocytes through interference with cytoskeletal polarization
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Christoph Wülfing, Rachel Ambler, David J. Morgan, Stephen Cross, Alamir H, Milodowski E, Gabriel L. Galea, Grace L. Edmunds, and Wong Cc
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Tumor microenvironment ,CTL ,medicine.anatomical_structure ,Chemistry ,T cell ,medicine ,Cancer research ,Cytotoxic T cell ,Priming (immunology) ,Adenosine ,CD8 ,Ex vivo ,medicine.drug - Abstract
Tumors generate an immune-suppressive environment that prevents effective killing of tumor cells by CD8+ cytotoxic T cells (CTL). It remains largely unclear upon which cell type and at which stage of the anti-tumor response mediators of suppression act. We have combined an in vivo tumor model with a matching in vitro reconstruction of the tumor microenvironment based on tumor spheroids to identify suppressors of anti-tumor immunity that directly act on interaction between CTL and tumor cells and to determine mechanisms of action. An adenosine 2a receptor antagonist, as enhanced by blockade of TIM3, slowed tumor growth in vivo. Engagement of the adenosine 2a receptor and TIM3 reduced tumor cell killing in spheroids, impaired CTL cytoskeletal polarization ex vivo and in vitro and inhibited CTL infiltration into tumors and spheroids. With this focus on CTL killing, blocking A2aR and TIM3 complements therapies that enhance T cell priming, e.g. anti-PD1 and anti-CTLA-4.
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- 2021
25. Hindbrain neuropore tissue geometry determines asymmetric cell-mediated closure dynamics in mouse embryos
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Gabriel L. Galea, Shiladitya Banerjee, Nicholas D. E. Greene, Abigail R. Marshall, Eirini Maniou, Michael F. Staddon, and Andrew J. Copp
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Male ,Neural Tube ,Leading edge ,animal structures ,Closure (topology) ,Mice, Transgenic ,Nerve Tissue Proteins ,Geometry ,Hindbrain ,physical modeling ,Time-Lapse Imaging ,hindbrain neuropore ,biomechanics ,medicine ,Animals ,Tensin ,Process (anatomy) ,mouse ,Mice, Knockout ,Anencephaly ,Microscopy, Confocal ,Multidisciplinary ,Chemistry ,Neural tube ,Biological Sciences ,Cadherins ,Embryo, Mammalian ,Surface ectoderm ,Embryonic stem cell ,Fibronectins ,Mice, Inbred C57BL ,Rhombencephalon ,medicine.anatomical_structure ,Neural Crest ,Female ,Laminin ,Developmental Biology - Abstract
Significance Failure to biomechanically close the embryonic neural tube in the developing brain causes fatal anencephaly. Despite their clinical importance, which cellular force-generating mechanisms close the neural tube remains poorly understood. This interdisciplinary study combines morphometric analysis, mouse embryo live imaging, and in silico modeling to formally identify cellular behaviors which complete midbrain/hindbrain closure. Two cellular force-generating behaviors not previously appreciated to act in this context are identified: contractility of supracellular actomyosin purse strings around the gap and directional movement of cells toward the gap. Both these mechanisms are required to describe gap closure, and their resulting dynamics are substantially impacted by morphogenetically imposed tissue geometry. This work provides a broadly applicable biophysical framework underlying fatal failures of midbrain/hindbrain closure., Gap closure is a common morphogenetic process. In mammals, failure to close the embryonic hindbrain neuropore (HNP) gap causes fatal anencephaly. We observed that surface ectoderm cells surrounding the mouse HNP assemble high-tension actomyosin purse strings at their leading edge and establish the initial contacts across the embryonic midline. Fibronectin and laminin are present, and tensin 1 accumulates in focal adhesion-like puncta at this leading edge. The HNP gap closes asymmetrically, faster from its rostral than caudal end, while maintaining an elongated aspect ratio. Cell-based physical modeling identifies two closure mechanisms sufficient to account for tissue-level HNP closure dynamics: purse-string contraction and directional cell motion implemented through active crawling. Combining both closure mechanisms hastens gap closure and produces a constant rate of gap shortening. Purse-string contraction reduces, whereas crawling increases gap aspect ratio, and their combination maintains it. Closure rate asymmetry can be explained by asymmetric embryo tissue geometry, namely a narrower rostral gap apex, whereas biomechanical tension inferred from laser ablation is equivalent at the gaps’ rostral and caudal closure points. At the cellular level, the physical model predicts rearrangements of cells at the HNP rostral and caudal extremes as the gap shortens. These behaviors are reproducibly live imaged in mouse embryos. Thus, mammalian embryos coordinate cellular- and tissue-level mechanics to achieve this critical gap closure event.
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- 2021
26. Susceptibility of South Texas Aedes aegypti to Pyriproxyfen
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Gabriel L. Hamer, Alyssa Branca, Michael G. Banfield, Jose G. Juarez, Christopher M Roundy, and Selene M. Garcia-Luna
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Aedes aegypti ,Veterinary medicine ,Science ,030231 tropical medicine ,vector control ,emergence inhibition ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Chemical products ,Insect growth regulator ,Bioassay ,Intervention trial ,pyriproxyfen ,030304 developmental biology ,0303 health sciences ,Larva ,biology ,autodissemination ,Field population ,biology.organism_classification ,chemistry ,insect growth regulator ,Insect Science ,Pyriproxyfen - Abstract
An integral part to integrated mosquito management is to ensure chemical products used for area-wide control are effective against a susceptible population of mosquitoes. Prior to conducting an intervention trial using an insect growth regulator, pyriproxyfen, in South Texas to control Aedes aegypti, we conducted a larval bioassay to evaluate baseline levels of susceptibility. We used seven serially-diluted doses ranging from 2.5 ppb to 6.3 × 10−4 ppb. We observed 100% inhibition emergence (IE) at even the lowest dose of 6.3 × 10−4 ppb in our susceptible reference colony of Ae. aegypti Liverpool. In our field strain of Ae. aegypti (F5 colonized from South Texas) we observed 79.8% IE at 6.3 × 10−4 ppb, 17.7% IE at 1.25 × 10−3 ppb, 98.7% IE at 1.25 × 10−2 ppb, and 100% emergence inhibition for the remainder of the doses. Given that commercial pyriproxyfen products are labeled for doses ranging to 50 ppb, we conclude that the field population sampled by this study are susceptible to this insect growth regulator.
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- 2021
27. Ponatinib treatment promotes arterial thrombosis and hyperactive platelets
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Evi X. Stavrou, Gabriel L Forbes, Alvin H. Schmaier, Alona Merkulova, and Steven C. Mitchell
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Blood Platelets ,0301 basic medicine ,medicine.medical_specialty ,Reactive oxygen species metabolism ,Antineoplastic Agents ,030204 cardiovascular system & hematology ,Platelet reactivity ,Mice ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Internal medicine ,Animals ,Medicine ,Drug Interactions ,Platelet ,Protein Kinase Inhibitors ,Pioglitazone ,business.industry ,Extramural ,Ponatinib ,Imidazoles ,Thrombosis ,Arteries ,Hematology ,medicine.disease ,Stimulus Report ,Pyridazines ,Disease Models, Animal ,030104 developmental biology ,chemistry ,Cardiology ,Reactive Oxygen Species ,business ,Biomarkers ,Thrombotic complication ,medicine.drug - Abstract
Key Points Ponatinib therapy heightens arterial thrombosis and platelet reactivity. Concurrent pioglitazone treatment reverses heightened thrombosis risk and platelet reactivity induced by ponatinib.
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- 2019
28. Application of layered double hydroxides for 99Tc remediation
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A. Hölzer, Yaqi Ji, C. Walther, Gabriel L. Murphy, N. Torapava, Kristina O. Kvashnina, H. Si, Andrey Bukaemskiy, V. Petrov, Piotr M. Kowalski, C. Franzen, and N. Daniels
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Aqueous solution ,Absorption spectroscopy ,Ion exchange ,Chemistry ,Environmental remediation ,Inorganic chemistry ,Layered double hydroxides ,020101 civil engineering ,Geology ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,Hydrothermal circulation ,0201 civil engineering ,Ion ,Fast release ,Geochemistry and Petrology ,engineering ,0210 nano-technology - Abstract
The present study investigates possible use of Layered Double Hydroxides (LDH) for Tc(VII) remediation. Mg/Al– and Mg/Fe–LDH were obtained by a hydrothermal route and thermally activated at 450 °C, which was shown to significantly improve the Tc(VII) removal efficiency. Based on XRD investigation of Tc–LDH phases, the uptake Tc(VII) from the solution follows the restoring of a LDH structure. X-ray absorption spectroscopy demonstrates that Tc ions interact solely via the Tc O bond, leaving no evidences of farther atomic interactions with, e.g., layers of LDH. The presence of competing anions, like NO3−, or CO32– in the solution decreases Tc(VII) uptake by LDH. Maximum uptake capacity of thermally activated Mg0.67/Al0.33-LDH and Mg0.75/Fe0.25–LDH were derived from fitting the experimental data into the modified Langmuir equation and correspondingly comprise 0.227 mol/kg and 0.213 mol/kg. In agreement with these findings, theoretical simulations predicted incorporation energies for Mg0.67/Al0.33–LDH and Mg0.75/Fe0.25–LDH of −128 kJ/mol and − 110 kJ/mol, respectively. Investigation of stability of Tc–LDH in different aqueous solutions demonstrated a rather low release Tc(VII) in contact with diluted solutions containing Cl− and OH−, however, in a high saline solution, like Q-brine a rather fast release of TcO4− occurs due to anion exchange with Cl−.
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- 2019
29. A selective membrane-targeting repurposed antibiotic with activity against persistent methicillin-resistant Staphylococcus aureus
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Gabriel L. Hendricks, Kiho Lee, Xiaowen Huang, Taylor P. A. Hari, Jenna Port, Frederick M. Ausubel, Madeline M Dekarske, Noelly Queiroz Ribeiro, Hammad A. Faizi, Jake L Rosen, Andrew D. Steele, Wen Pan, Beth Burgwyn Fuchs, Guijin Zou, William M. Wuest, Eleftherios Mylonakis, Wenpeng Zhu, Nicolas Galle, Erika E Csatary, Petia M. Vlahovska, Huajian Gao, Ingrid K. Wilt, Katerina Tori, and Wooseong Kim
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0301 basic medicine ,Multidisciplinary ,Multidrug tolerance ,medicine.drug_class ,030106 microbiology ,Antibiotics ,medicine.disease_cause ,Antimicrobial ,Methicillin-resistant Staphylococcus aureus ,Microbiology ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,Bithionol ,chemistry ,medicine ,Membrane fluidity ,Gentamicin ,Lipid bilayer ,medicine.drug - Abstract
Treatment of Staphylococcus aureus infections is complicated by the development of antibiotic tolerance, a consequence of the ability of S. aureus to enter into a nongrowing, dormant state in which the organisms are referred to as persisters. We report that the clinically approved anthelmintic agent bithionol kills methicillin-resistant S. aureus (MRSA) persister cells, which correlates with its ability to disrupt the integrity of Gram-positive bacterial membranes. Critically, bithionol exhibits significant selectivity for bacterial compared with mammalian cell membranes. All-atom molecular dynamics (MD) simulations demonstrate that the selectivity of bithionol for bacterial membranes correlates with its ability to penetrate and embed in bacterial-mimic lipid bilayers, but not in cholesterol-rich mammalian-mimic lipid bilayers. In addition to causing rapid membrane permeabilization, the insertion of bithionol increases membrane fluidity. By using bithionol and nTZDpa (another membrane-active antimicrobial agent), as well as analogs of these compounds, we show that the activity of membrane-active compounds against MRSA persisters positively correlates with their ability to increase membrane fluidity, thereby establishing an accurate biophysical indicator for estimating antipersister potency. Finally, we demonstrate that, in combination with gentamicin, bithionol effectively reduces bacterial burdens in a mouse model of chronic deep-seated MRSA infection. This work highlights the potential repurposing of bithionol as an antipersister therapeutic agent.
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- 2019
30. Electron interactions with 1,2-ethylenediamine and dimethyldiazene
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Gabriel L. C. de Souza
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Physics ,Elastic scattering ,Radiation ,010304 chemical physics ,Scattering ,Momentum transfer ,Ethylenediamine ,02 engineering and technology ,Electron ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Molecular physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,0103 physical sciences ,Padé approximant ,Molecule ,Physical and Theoretical Chemistry ,0210 nano-technology ,Polarization (electrochemistry) ,Spectroscopy - Abstract
In this work, a theoretical investigation on the electron interactions with 1,2-ethylenediamine and dimethyldiazene (also known as azomethane) is presented. Differential cross sections (DCS), integral cross sections (ICS), and momentum transfer cross sections (MTCS) for elastic scattering as well as total cross sections (TCS) and total absorption cross sections were determined in the 1-500 eV range. To describe the electron-target interaction and solve the scattering equations, a molecular complex optical potential (MCOP) approach combined with the Pade approximant technique was employed. Regarding the DCS, 1,2-ethylenediamine presented the f-wave pattern which was not seen in the results of dimethyldiazene. On the other hand, results of dimethyldiazene have shown a sharp feature at 2.0 eV in the ICS, MTCS, and TCS, which was assigned as the π* resonance originating from the nitrogen–nitrogen bond. Interestingly, the feature observed in dimethyldiazene was found to be slightly shifted toward low energy when compared to the resonance reported for the N2 molecule. The description of the polarization effects could be responsible for this discrepancy, and the methylation effect be responsible for the stabilization of the π* resonance of dimethyldiazene with respect to N2. To the best of our knowledge, this work represents the first extensive study regarding electron collisions with these molecules, being presented to motivate experimental investigations to be performed about these important and widely used building blocks.
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- 2019
31. Controlling Oxygen Defect Formation and Its Effect on Reversible Symmetry Lowering and Disorder-to-Order Phase Transformations in Nonstoichiometric Ternary Uranium Oxides
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Gabriel L. Murphy, Maxim Avdeev, Brendan J. Kennedy, Qinfen Gu, Ondrej Muránsky, Zhaoming Zhang, Chun-Hai Wang, George Beridze, Piotr M. Kowalski, and Helen E. A. Brand
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Alkaline earth metal ,010405 organic chemistry ,Chemistry ,Superlattice ,chemistry.chemical_element ,Triclinic crystal system ,010402 general chemistry ,01 natural sciences ,Oxygen ,0104 chemical sciences ,Inorganic Chemistry ,Crystallography ,Ab initio quantum chemistry methods ,Physical and Theoretical Chemistry ,Isostructural ,Ternary operation ,Stoichiometry - Abstract
In situ synchrotron powder X-ray diffraction measurements have demonstrated that the isostructural AUO4- x ( A = alkaline earth metal cation) oxides CaUO4- x and α-Sr0.4Ca0.6UO4- x undergo a reversible phase transformation under reducing conditions at high temperatures associated with the ordering of in-plane oxygen vacancies resulting in the lowering of symmetry. When rhombohedral (space group R3 m) CaUO4- x and α-Sr0.4Ca0.6UO4- x are heated to 450 and 400 °C, respectively, in a hydrogen atmosphere, they undergo a first-order phase transformation to a single phase structure which can be refined against a triclinic model in space group P1, δ-CaUO4- x and δ-Sr0.4Ca0.6UO4- x, where the oxygen vacancies are disordered initially. Continued heating results in the appearance of superlattice reflections, indicating the ordering of in-plane oxygen vacancies. Cooling ordered δ-CaUO4- x and δ-Sr0.4Ca0.6UO4- x to near room temperature results in the reformation of the disordered rhombohedral phases. Essential to the transformation is the generation of a critical amount of oxygen vacancies. Once these are formed, the transformation can be accessed continuously through thermal cycling, showing that the transformations are purely thermodynamic in origin. Stoichiometric structures of both oxides can be recovered by heating oxygen deficient CaUO4- x and α-Sr0.4Ca0.6UO4- x under pure oxygen to high temperatures. When heated in air, the amount of oxygen vacancy defects that form in CaUO4- x and α-Sr0.4Ca0.6UO4- x are found to correlate with the A site composition. The inclusion of the larger Sr2+ cation on the A site reduces defect-defect interactions, which increases the amount of defects that can form and lowers their formation temperature. The relative difference in the amount of defects that form can be understood on the basis of oxygen vacancy and U5+ disordering as shown by both ab initio calculations and estimated oxygen vacancy formation energies based on thermodynamic considerations. This difference in defect-defect interactions consequently introduces variations in the long-range ordered anionic lattice of the δ phases despite the isostructural relationship of the α structures of CaUO4- x and Sr0.4Ca0.6UO4- x. These results are discussed with respect to the influence the A site cation has upon anion defect formation and ordering and are also compared to δ-SrUO4- x, the only other material known to be able to undergo a reversible symmetry lowering and disorder-to-order transformation with increasing temperature.
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- 2019
32. Multivariate data analysis of trace elements in bivalve molluscs: Characterization and food safety evaluation
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Geysa B. Brito, Leonardo S. G. Teixeira, Luana Novaes Santos, Gabriel L. Santos, Isa S. Barbosa, Maria das Graças Andrade Korn, and Rennan Geovanny Oliveira Araujo
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Oyster ,Food Safety ,Food Contamination ,01 natural sciences ,Mass Spectrometry ,Analytical Chemistry ,0404 agricultural biotechnology ,biology.animal ,Animals ,Cluster Analysis ,Humans ,Microwave digestion ,Microwaves ,Inductively coupled plasma mass spectrometry ,Shellfish ,Principal Component Analysis ,biology ,Chemistry ,010401 analytical chemistry ,04 agricultural and veterinary sciences ,General Medicine ,Mussel ,biology.organism_classification ,040401 food science ,Trachycardium ,Bivalvia ,Trace Elements ,0104 chemical sciences ,Certified reference materials ,Metals ,Environmental chemistry ,Inductively coupled plasma atomic emission spectroscopy ,Multivariate Analysis ,Inductively coupled plasma ,Brazil ,Food Science - Abstract
Four species of bivalve molluscs (Anomalocardia brasiliana, Iphigenia brasiliana, Lucina pectinata and Trachycardium muricatum) were collected in the Todos os Santos Bay (TSB), Bahia, Brazil, in order to evaluate As, Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb, Se, V and Zn levels and, consequently, the risk of bivalve mollusc consumption in humans. The samples were analyzed by inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) after closed-vessel microwave digestion. The accuracy was confirmed using the certified reference materials of oyster tissue (NIST 1566b) and mussel tissue (NIST 2977), and the results were statistically equivalent to the certified values. Application of principal component analysis (PCA) and hierarchical cluster analysis (HCA) showed a tendency to form two groups between samples of Lucina pectinata and Trachycardium muricatum. All species showed As and Cr concentrations higher than the maximum tolerable limit specified in Brazilian legislation.
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- 2019
33. The radiation chemistry of focused electron-beam induced etching of copper in liquids
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Eric Cao, J. Todd Hastings, Gabriel L. Smith, and Sarah K. Lami
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Materials science ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,Radiation chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Copper ,0104 chemical sciences ,Reaction rate ,Interferometry ,chemistry ,Oxidizing agent ,Cathode ray ,General Materials Science ,0210 nano-technology ,Environmental scanning electron microscope ,Electron scattering - Abstract
Well-controlled, focused electron-beam induced etching of copper thin films has been successfully conducted on bulk substrates in an environmental scanning electron microscope by controlling liquid-film thickness with an in situ correlative interferometry system. Knowledge of the liquid-film thickness enables a hybrid Monte Carlo/continuum model of the radiation chemistry to accurately predict the copper etch rate using only electron scattering cross-sections, radical yields, and reaction rates from previous studies. Etch rates depended strongly on the thickness of the liquid film and simulations confirmed that this was a result of increased oxidizing radical generation. Etch rates also depended strongly, but non-linearly, on electron beam current, and simulations showed that this effect arises through the dose-rate dependence of reactions of radical species.
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- 2019
34. Influence of electrodeposition temperature in the electrochemical properties of Ni(OH)2: An experimental and theoretical study
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Gabriel L. C. de Souza, Y. Leyet, Ailton José Terezo, E.H.N.S. Thaines, L. A. Pocrifka, Y. Romaguera-Barcelay, L. Aguilera, R.G. Freitas, and Raimundo R. Passos
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010302 applied physics ,Materials science ,Metals and Alloys ,chemistry.chemical_element ,02 engineering and technology ,Surfaces and Interfaces ,Substrate (electronics) ,Electrolyte ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Capacitance ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Dielectric spectroscopy ,Nickel ,chemistry ,Chemical engineering ,0103 physical sciences ,Materials Chemistry ,Density functional theory ,Cyclic voltammetry ,0210 nano-technology - Abstract
In the present work, electrodeposition different temperatures are employed to obtain nickel hydroxide films on titanium substrate. The influence of this parameter on the electrochemical properties of the material is studied. The films are morphologically and structurally characterized using techniques of X-Ray Diffraction and Scanning Electronic Microscopy. The density functional theory (DFT) calculations are performed to study the effect of strain applied along the Ni(OH)2 unit cell and electron density maps are performed to relate with electrochemical properties. For the electrochemical characterization are used cyclic voltammetry, galvanostatic charge- discharge and electrochemical impedance spectroscopy techniques. The films deposited at 10 °C, development a structure which favors the charge storage, both in those more accessible surfaces, and in those of more difficult access, by electrolyte ions. This fact is in correspondence with the DFT results for this temperature that suggests an improvement in the material electrochemical properties, showing a high capacitance value (2549 F g1).
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- 2019
35. High-Pressure Synthesis, Structural, and Spectroscopic Studies of the Ni–U–O System
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Brendan J. Kennedy, Philip Kegler, Martin D. de Jonge, Yingjie Zhang, Gabriel L. Murphy, Evgeny V. Alekseev, and Zhaoming Zhang
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Diffraction ,Chemistry ,02 engineering and technology ,Triclinic crystal system ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,Crystallography ,Polyhedron ,Zigzag ,Group (periodic table) ,Rutile ,Orthorhombic crystal system ,Physical and Theoretical Chemistry ,Isostructural ,0210 nano-technology - Abstract
The first comprehensive structural study of the Ni–U–O system is reported. Single crystals of α-NiUO4, β-NiUO4, and NiU3O10 were synthesized, and their structures were refined—using synchrotron single-crystal X-ray diffraction data supported by X-ray absorption spectroscopic measurements. α-NiUO4 adopts an orthorhombic structure in space group Pbcn and is isostructural to CrUO4 containing corrugated two-dimensional (2D) layers of corner-sharing UO6 polyhedra and edge-sharing one-dimensional (1D) zigzag α-PbO2 rutile-like chains of NiO6 polyhedra in the [001] direction. β-NiUO4 is isostructural to MgUO4 and has an orthorhombic structure in space group Ibmm, which contains alternating 1D chains of edge-sharing UO6 and NiO6 polyhedra in the [001] direction as in regular TiO2 rutile. NiU3O10 forms a triclinic structure in space group P1 and is isostructural with CuU3O10, where it forms a three-dimensional (3D) framework structure built through a mixture of UO6 and UO7 polyhedra in which the NiO6 polyhedra si...
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- 2018
36. Aerobic Solid State Red Phosphorescence from Benzobismole Monomers and Patternable Self-Assembled Block Copolymers
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Inara de Aguiar, Haoyang Yu, Letian Xu, Gunwant K. Matharu, Michael J. Ferguson, Robert McDonald, Emanuel Hupf, Michael P. Boone, Gang He, Alex Brown, Eric Rivard, Sarah M. Parke, and Gabriel L. C. de Souza
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Materials science ,010405 organic chemistry ,chemistry.chemical_element ,General Chemistry ,ROMP ,General Medicine ,Metathesis ,010402 general chemistry ,Micelle ,01 natural sciences ,Catalysis ,Bismuth ,0104 chemical sciences ,chemistry.chemical_compound ,Monomer ,chemistry ,Chemical engineering ,Copolymer ,Phosphorescence ,Macromolecule - Abstract
The synthesis of the first bismuth-containing macromolecules that exhibit phosphorescence in the solid state and in the presence of oxygen is reported. These red emissive high molecular weight polymers (>300 kDa) feature benzobismoles appended to a hydrocarbon scaffold, and were built via an efficient ring-opening metathesis (ROMP) protocol. Moreover, our general procedure readily allows for the formation of cross-linked networks and block copolymers. Attaining stable red phosphorescence with non-toxic elements remains a challenge and, thus, our new class of soluble (processable) polymeric phosphor is of great interest. Furthermore, the formation of bismuth-rich cores within organic-inorganic block copolymer spherical micelles is possible, leading to patterned arrays of bismuth in the film state.
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- 2018
37. Tilting and Distortion in Rutile-Related Mixed Metal Ternary Uranium Oxides: A Structural, Spectroscopic, and Theoretical Investigation
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Philip Kegler, Eugenia Y. Kuo, Brendan J. Kennedy, Zhaoming Zhang, Gabriel L. Murphy, Evgeny V. Alekseev, Piotr M. Kowalski, Daniel J. Gregg, Maxim Avdeev, and Rebekka Tesch
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Diffraction ,X-ray absorption spectroscopy ,Phase transition ,010405 organic chemistry ,Chemistry ,Context (language use) ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,Crystallography ,Ab initio quantum chemistry methods ,ddc:540 ,Physical and Theoretical Chemistry ,Ternary operation ,Single crystal ,Powder diffraction - Abstract
A systematic investigation examining the origins of structural distortions in rutile-related ternary uranium AUO4 oxides using a combination of high-resolution structural and spectroscopic measurements supported by ab initio calculations is presented. The structures of β-CdUO4, MnUO4, CoUO4, and MgUO4 are determined at high precision by using a combination of neutron powder diffraction (NPD) and synchrotron X-ray powder diffraction (S-XRD) or single crystal X-ray diffraction. The structure of β-CdUO4 is best described by space group Cmmm whereas MnUO4, CoUO4, and MgUO4 are described by the lower symmetry Ibmm space group and are isostructural with the previously reported β-NiUO4 [Murphy et al. Inorg. Chem.2018, 57, 13847]. X-ray absorption spectroscopy (XAS) analysis shows all five oxides contain hexavalent uranium. The difference in space group can be understood on the basis of size mismatch between the A2+ and U6+ cations whereby unsatisfactory matching results in structural distortions manifested through tilting of the AO6 polyhedra, leading to a change in symmetry from Cmmm to Ibmm. Such tilts are absent in the Cmmm structure. Heating the Ibmm AUO4 oxides results in reduction of the tilt angle. This is demonstrated for MnUO4 where in situ S-XRD measurements reveal a second-order phase transition to Cmmm near T = 200 °C. Based on the extrapolation of variable temperature in situ S-XRD data, CoUO4 is predicted to undergo a continuous phase transition to Cmmm at ∼1475 °C. Comparison of the measured and computed data highlights inadequacies in the DFT+U approach, and the conducted analysis should guide future improvements in computational methods. The results of this investigation are discussed in the context of the wider AUO4 family of oxides.
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- 2021
38. Incorporation of iodine into uranium oxyhydroxide phases
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Andreas Wilden, Dimitri Schneider, Gabriel L. Murphy, Evgeny V. Alekseev, Maximilian Henkes, Martina Klinkenberg, and Philip Kegler
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Inorganic Chemistry ,Aqueous solution ,chemistry ,Phase (matter) ,Inorganic chemistry ,Radiolysis ,Intercalation (chemistry) ,ddc:540 ,chemistry.chemical_element ,Uranium ,Inductively coupled plasma ,Hydrothermal circulation ,Ion - Abstract
Herein, we have synthesised a novel uranium oxyhydroxide (UOH) phase, Rb2K2[(UO2)6O4(OH)6]·(IO3)2, under hydrothermal conditions which intercalates IO3− via a hybrid salt-inclusion and host–guest mechanism. The mechanism is based on favorable intermolecular bonding between disordered Rb+/K+ and IO3− ions and hydroxyl and layer void positions respectively. To examine whether the intercalation may occur ubiquitously for UOH phases, the known UOH mineral phases metaschoepite ([(UO2)8O2(OH)12]·12H2O), compreignacite (K2[(UO2)6O4(OH)6]·7H2O) and also related β-UO2(OH)2 were synthesised and exposed to aqueous I− and IO3− for 1 month statically at RT and 60 °C in air and the solid analysed using laser ablation inductively coupled plasma mass spectroscopy. Measurements indicate intercalation can occur homogeneously, but the affinity is dependent upon the structure of the UOH phases and temperature, where higher temperatures and when the interlayer space is free of initial moieties are favoured. It was also found that after repeated washing of the UOH samples with DI water the intercalated iodine was retained. UOH phases are known to form during the oxidative corrosion of spent nuclear fuel during an accident scenario in the near field, this work suggests they may help retard the transport of radiolytic iodine into the environment during a long-term release event.
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- 2021
39. The Role of Acidity in the Synthesis of Novel Uranyl Selenate and Selenite Compounds and Their Structures
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Gabriel L. Murphy, Eike M. Langer, Philip Kegler, and Evgeny V. Alekseev
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Crystallography ,selenate ,General Chemical Engineering ,Context (language use) ,Triclinic crystal system ,Condensed Matter Physics ,Uranyl ,Selenate ,uranium ,Inorganic Chemistry ,chemistry.chemical_compound ,Tetragonal crystal system ,chemistry ,QD901-999 ,Functional group ,ddc:540 ,General Materials Science ,Orthorhombic crystal system ,selenite ,Single crystal - Abstract
Herein, the novel uranyl selenate and selenite compounds Rb2[(UO2)2(SeO4)3], Rb2[(UO2)3(SeO3)2O2], Rb2[UO2(SeO4)2(H2O)]·2H2O, and (UO2)2(HSeO3)2(H2SeO3)2Se2O5 have been synthesized using either slow evaporation or hydrothermal methods under acidic conditions and their structures were refined using single crystal X-ray diffraction. Rb2[(UO2)2(SeO4)3] synthesized hydrothermally adopts a layered 2D tetragonal structure in space group P42/ncm with a = 9.8312(4) Å, c = 15.4924(9) Å, and V = 1497.38(15) Å, where it consists of UO7 polyhedra coordinated via SeO4 units to create units UO2(SeO4)58− moieties which interlink to create layers in which Rb+ cations reside in the interspace. Rb2[(UO2)3(SeO3)2O2] synthesized hydrothermally adopts a layered 2D triclinic structure in space group P1¯ with a = 7.0116(6) Å, b = 7.0646(6) Å, c = 8.1793(7) Å, α = 103.318(7)°, β = 105.968(7)°, γ = 100.642(7)° and V = 365.48(6) Å3, where it consists of edge sharing UO7, UO8 and SeO3 polyhedra that form [(UO2)3(SeO3)2O2] layers in which Rb+ cations are found in the interlayer space. Rb2[UO2(SeO4)2(H2O)]·2H2O synthesized hydrothermally adopts a chain 1D orthorhombic structure in space group Pmn21 with a = 13.041(3) Å, b = 8.579(2) Å, c = 11.583(2) Å, and V = 1295.9(5) Å3, consisting of UO7 polyhedra that corner share with one H2O and four SeO42− ligands, creating infinite chains. (UO2)2(HSeO3)2(H2SeO3)2Se2O5 synthesized under slow evaporation conditions adopts a 0D orthorhombic structure in space group Cmc21 with a = 28.4752(12) Å, b = 6.3410(3) Å, c = 10.8575(6) Å, and V = 1960.45(16) Å3, consisting of discrete rings of [(UO2)2(HSeO3)2(H2SeO3)2Se2O5]2. (UO2)2(HSeO3)2(H2SeO3)2Se2O5 is apparently only the second example of a uranyl diselenite compound to be reported. A combination of single crystal X-ray diffraction and bond valance sums calculations are used to characterise all samples obtained in this investigation. The structures uncovered in this investigation are discussed together with the broader family of uranyl selenates and selenites, particularly in the context of the role acidity plays during synthesis in coercing specific structure, functional group, and topology formations.
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- 2021
40. Glycine Cleavage System H Protein Is Essential for Embryonic Viability, Implying Additional Function Beyond the Glycine Cleavage System
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Andrew J. Copp, Kit-Yi Leung, Sandra C. P. De Castro, Gabriel L. Galea, and Nicholas D. E. Greene
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0301 basic medicine ,Hyperglycinemia ,lcsh:QH426-470 ,Mutant ,medicine.disease_cause ,GCSH ,03 medical and health sciences ,0302 clinical medicine ,lipoylation ,medicine ,Genetics ,mouse models ,Aminomethyltransferase ,Genetics (clinical) ,Original Research ,glycine cleavage system H protein ,Mutation ,Glycine cleavage system ,embryonic lethality ,Chemistry ,medicine.disease ,Null allele ,Cell biology ,glycine cleavage system ,lcsh:Genetics ,030104 developmental biology ,Glycine ,Molecular Medicine ,030217 neurology & neurosurgery - Abstract
Glycine cleavage system H protein (GCSH) is a component of the glycine cleavage system (GCS), a conserved protein complex that acts to decarboxylate glycine. Mutation ofAMTorGLDC, encoding the GCS components aminomethyltransferase and glycine decarboxylase, can cause malformations of the developing CNS (neural tube defects (NTDs) and ventriculomegaly) as well as a post-natal life-limiting neurometabolic disorder, Non-Ketotic Hyperglycinemia. In contrast, it is unclear whether mutation ofGCSHcontributes to these conditions and we therefore investigated GCSH loss of function in mice. Mice that were heterozygous for aGcshnull allele were viable and did not exhibit elevated plasma glycine. Moreover, heterozygous mutation ofGcshdid not increase the frequency of NTDs inGldcmutant embryos. HomozygousGcshnull mice were not recovered at post-natal stages. Analysis of litters at E8.5-10.5, revealed the presence of homozygous null embryos which were much smaller than littermates and had failed to develop beyond early post-implantation stages with no visible somites or head-folds. Hence, unlike null mutations ofGldcorAmt, which are compatible with embryonic survival despite the presence of NTDs, loss ofGcshcauses embryonic death prior to mid-gestation. Maternal supplementation with formate did not restore embryonic development beyond E7.5, suggesting that the primary cause of lethality was not loss of glycine cleavage activity or suppression of folate one-carbon metabolism. These findings suggest that GCSH has additional roles beyond function in the glycine cleavage system. We hypothesize that GCSH potentially acts in lipoylation of 2-oxoacid dehydrogenase proteins, as reported in bacteria.
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- 2021
41. Interpretable machine learning model to detect chemically adulterated urine samples analyzed by high resolution mass spectrometry
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Lars C. Ebert, Gabriel L Streun, Andrea E. Steuer, Akos Dobay, Thomas Kraemer, University of Zurich, and Kraemer, Thomas
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0301 basic medicine ,Sample (material) ,Clinical Biochemistry ,340 Law ,610 Medicine & health ,Urine ,1308 Clinical Biochemistry ,2704 Biochemistry (medical) ,Machine learning ,computer.software_genre ,Mass spectrometry ,Biochemistry ,medical ,01 natural sciences ,Mass Spectrometry ,Machine Learning ,03 medical and health sciences ,510 Mathematics ,Humans ,Artificial neural network ,business.industry ,Chemistry ,010401 analytical chemistry ,Biochemistry (medical) ,General Medicine ,10218 Institute of Legal Medicine ,0104 chemical sciences ,Substance Abuse Detection ,030104 developmental biology ,Pharmaceutical Preparations ,Feature (computer vision) ,Test set ,Potential biomarkers ,Artificial intelligence ,business ,Urine sample ,computer ,Chromatography, Liquid - Abstract
Objectives Urine sample manipulation including substitution, dilution, and chemical adulteration is a continuing challenge for workplace drug testing, abstinence control, and doping control laboratories. The simultaneous detection of sample manipulation and prohibited drugs within one single analytical measurement would be highly advantageous. Machine learning algorithms are able to learn from existing datasets and predict outcomes of new data, which are unknown to the model. Methods Authentic human urine samples were treated with pyridinium chlorochromate, potassium nitrite, hydrogen peroxide, iodine, sodium hypochlorite, and water as control. In total, 702 samples, measured with liquid chromatography coupled to quadrupole time-of-flight mass spectrometry, were used. After retention time alignment within Progenesis QI, an artificial neural network was trained with 500 samples, each featuring 33,448 values. The feature importance was analyzed with the local interpretable model-agnostic explanations approach. Results Following 10-fold cross-validation, the mean sensitivity, specificity, positive predictive value, and negative predictive value was 88.9, 92.0, 91.9, and 89.2%, respectively. A diverse test set (n=202) containing treated and untreated urine samples could be correctly classified with an accuracy of 95.4%. In addition, 14 important features and four potential biomarkers were extracted. Conclusions With interpretable retention time aligned liquid chromatography high-resolution mass spectrometry data, a reliable machine learning model could be established that rapidly uncovers chemical urine manipulation. The incorporation of our model into routine clinical or forensic analysis allows simultaneous LC-MS analysis and sample integrity testing in one run, thus revolutionizing this field of drug testing.
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- 2021
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42. Electronic structure and mechanism for the uptake of nitric oxide by the Ru(iii) antitumor complex NAMI-A
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Willian R. Rocha, Eufrásia S. Pereira, and Gabriel L. S. Rodrigues
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010405 organic chemistry ,Chemistry ,General Chemical Engineering ,chemistry.chemical_element ,General Chemistry ,Electronic structure ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Gibbs free energy ,Ruthenium ,symbols.namesake ,Electron transfer ,Reaction rate constant ,Potential energy surface ,symbols ,Physical chemistry ,Density functional theory ,Singlet state - Abstract
Nitric oxide (NO) has well known vasodilation effects in living organisms and its participation in the metastasis of cancer cells through the angiogenesis process has been demonstrated experimentally. Therefore, the uptake of NO has become one focus of investigation to produce anti-metastatic drugs. In this article we have investigated the uptake of NO by the ruthenium based metallodrug trans-tetrachloride(dimethylsulfoxide)imidazole ruthenate(III) [Im]trans-[RuCl4(Im)(DMSO)], known as New Anti-tumor Metastasis Inhibitor-A (NAMI-A). Electronic structure calculations using Density Functional Theory, DFT, and State-Averaged Complete Active Space Self Consistent Field, SA-CASSCF, with second order perturbation theory corrections, NEVPT2 were carried out to investigate the mechanism involved in the uptake of NO by the Ru-based anticancer metallodrug NAMI-A. The calculations revealed that the reaction takes place at the triplet potential energy surface, with the singlet surface being ∼15 kcal mol−1 shifted to higher energies, and there is a surface crossing to form the most stable singlet product after the reaction takes place at the triplet surface. The spin pairing and electron transfer from the nitric oxide to the metallic fragment takes place at the region of the minimum energy crossing point between the two surfaces. The Ru–NO bond in the {Ru–NO}6 product has ∼10% of the RuIII–NO0 character. The SA-CASSCF/NEVPT2 calculations revealed that the uptake of NO by NAMI-A has a small energy barrier of ∼8 kcal mol−1 and, therefore a rate constant of 11.3 × 106 s−1 at 300 K. In addition, the reaction is thermodynamically favorable, with a Gibbs free energy of ∼30 kcal mol−1. These results show that the uptake of nitric oxide by the NAMI-A complex is kinetically and thermodynamically feasible in biological medium and, therefore, gives support to the anti-angiogenesis theory associated to the mode of action of NAMI-A and other related compounds.
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- 2020
43. Decision letter: Disparate bone anabolic cues activate bone formation by regulating the rapid lysosomal degradation of sclerostin protein
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Gabriel L. Galea and Tamara Alliston
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chemistry.chemical_compound ,Anabolism ,Chemistry ,Degradation (geology) ,Sclerostin ,Bone formation ,Cell biology - Published
- 2020
44. Extreme condition high temperature and high pressure studies of the K-U-Mo-O system
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Gabriel L. Murphy, Shuao Wang, Evgeny V. Alekseev, Martina Klinkenberg, and Philip Kegler
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Alkaline earth metal ,Materials science ,Valence (chemistry) ,Triclinic crystal system ,Uranyl ,Inorganic Chemistry ,Crystallography ,chemistry.chemical_compound ,chemistry ,ddc:540 ,Molecule ,Orthorhombic crystal system ,Single crystal ,Monoclinic crystal system - Abstract
Herein the first examples of alkali earth uranyl molybdates synthesised using extreme conditions of high temperature and high pressure (HT/HP) methods, namely K2[UO2(Mo2O7)2], K2[(UO2)2(Mo(vi)4Mo(iv)(OH)2)O16], K3[(UO2)6(OH)2(MoO4)6(MoO3OH)] and K5[(UO2)10MoO5O11OH]·H2O, are described and characterised. K2[UO2(Mo2O7)2] forms a monoclinic 2D layered structure in space group P21/c that consists of interlinking Mo2O7 dimers that link isolated UO22+ moieties forming [UO2(Mo2O7)2]2- layers which are separated by K+ cations. K2[(UO2)2(Mo(vi)4Mo(iv)(OH)2)O16] forms a disordered triclinic 3D framework structure in space group P1[combining macron]. The structure consists of isolated UO22+ moieties connected in a layered configuration via Mo(vi)O6 polyhedra of which the layers are bridged by Mo(iv)O6 polyhedra that are partially positionally disordered by charge balancing K+ and bridging Mo4+ cations. K3[(UO2)6(OH)2(MoO4)6(MoO3OH)] adopts a disordered orthorhombic 3D framework structure in space group Pbcm consisting of small channels and large cavities built upon corner sharing MoO4 and UO22+ moieties that respectively encapsulate ordered and disordered K+ cations. K5[(UO2)10MoO5O11OH]·H2O forms a triclinic 3D framework structure in space group P1[combining macron] consisting of interlinking UO6, UO7 and MoO5 polyhedra which utilise cation-cation interactions between UO22+ moieties to create infinite channels parallel to the [001] direction which contain partially disordered K+ cations and H2O molecules. A combination of single crystal X-ray diffraction, bond valence sums calculations and scanning electron microscopy with energy dispersive X-ray spectroscopic measurements was used to characterise all obtained samples in this investigation. The structures uncovered in this investigation are discussed systematically in detail with other members of the broader A+-U-Mo-O system from the literature where the relationship between the degree of pressure applied and U/Mo ratio used during synthesis on the ability to obtain high dimensional structures via condensation and oligomerization of polyhedra is identified and discussed in detail.
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- 2020
45. Hindbrain neuropore tissue geometry determines asymmetric cell-mediated closure dynamics
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Gabriel L. Galea, Abigail S. Marshall, Eirini Maniou, Andrew J. Copp, Shiladitya Banerjee, Nicholas D. E. Greene, and Michael F. Staddon
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Leading edge ,Critical gap ,animal structures ,Chemistry ,Geometry ,Hindbrain ,Cell migration ,Embryo tissue ,Surface ectoderm ,Embryonic stem cell ,Cell mediated immunity - Abstract
Gap closure is a common morphogenetic process. In mammals, failure to close the embryonic hindbrain neuropore (HNP) gap causes fatal anencephaly. We observed that surface ectoderm cells surrounding the mouse HNP assemble high-tension actomyosin purse-strings at their leading edge and establish the initial contacts across the embryonic midline. The HNP gap closes asymmetrically, faster from its rostral than caudal extreme, while maintaining an elongated aspect ratio. Cell-based physical modelling identifies two closure mechanisms sufficient to describe tissue-level HNP closure dynamics; purse-string contraction and directional cell crawling. Combining both closure mechanisms hastens gap closure and produces a constant rate of gap shortening. Purse-string contraction reduces, whereas crawling increases gap aspect ratio, and their combination maintains it. Closure rate asymmetry can be explained by embryo tissue geometry, namely a narrower rostral gap apex. At the cellular level, our model predicts highly directional cell migration with a constant rate of cells leaving the HNP rim. These behaviours are reproducibly live-imaged in mouse embryos. Thus, mammalian embryos coordinate cellular and tissue-level mechanics to achieve this critical gap closure event.
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- 2020
46. Photoinduced degradation of indigo carmine: insights from a computational investigation
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Mônica H. M. T. Assumpção, Sebastião C. da Silva, Flaviana S Candeias, Fernando Campanhã Vicentini, Alex Brown, Antonio H da S Filho, and Gabriel L. C. de Souza
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Physics ,010304 chemical physics ,Organic Chemistry ,Photodissociation ,010402 general chemistry ,01 natural sciences ,Molecular physics ,Quantum chemistry ,Catalysis ,0104 chemical sciences ,Computer Science Applications ,Inorganic Chemistry ,Photoexcitation ,chemistry.chemical_compound ,Computational Theory and Mathematics ,Indigo carmine ,chemistry ,Excited state ,0103 physical sciences ,Density functional theory ,Singlet state ,Physical and Theoretical Chemistry ,Ground state - Abstract
In this work, we present a computational investigation on the photoexcitation of indigo carmine (IC). Physical insights regarding IC photoexcitation and photolysis were obtained from a fundamental perspective through quantum chemistry computations. Density functional theory (DFT) was used to investigate the ground state while its time-dependent formalism (TD-DFT) was used for probing excited state properties, such as vertical excitation energies, generalized oscillator strengths (GOS), and structures. All the computations were undertaken using two different approaches: M06-2X/6-311+G(d,p) and CAM-B3LYP/6-311+G(d,p), in water. Results determined using both methods are in systematic agreement. For instance, the first singlet excited state was found at 2.28 eV (with GOS = 0.4730) and 2.19 eV (GOS = 0.4695) at the TD-DFT/CAM-B3LYP/6-311+G(d,p) and TD-DFT/M06-2X/6-311+G(d,p) levels of theory, respectively. Excellent agreement was observed between the computed and the corresponding experimental UV-Vis spectra. Moreover, results suggest IC undergoes photodecomposition through excited state chemical reaction rather than via a direct photolysis path. To the best of our knowledge, this work is the first to tackle the photoexcitation, and its potential connections to photodegradation, of IC from a fundamental chemical perspective, being presented with expectations to motivate further studies.
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- 2020
47. Nature of the bond, reduction potential, and solvation properties of ruthenium nitrosyl complexes of the type trans‐ [Ru( <scp> NH 3 </scp> ) 4 (L)( <scp>NO</scp> )] 2+/3+ and [Ru(salen)(L)( <scp>NO</scp> )] 2+/3+ in different charge and spin states
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Willian R. Rocha and Gabriel L. S. Rodrigues
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Reduction (complexity) ,Crystallography ,Spin states ,Chemistry ,Solvation ,chemistry.chemical_element ,Charge (physics) ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Ruthenium Compounds ,Atomic and Molecular Physics, and Optics ,Ruthenium - Published
- 2020
48. Examining the degradation of environmentally-daunting per- and poly-fluoroalkyl substances from a fundamental chemical perspective
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Antonio H da S Filho and Gabriel L. C. de Souza
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chemistry.chemical_classification ,General Physics and Astronomy ,Protonation ,02 engineering and technology ,010501 environmental sciences ,Sulfonic acid ,021001 nanoscience & nanotechnology ,01 natural sciences ,chemistry.chemical_compound ,chemistry ,Intramolecular force ,Excited state ,Perfluorooctanoic acid ,Degradation (geology) ,Physical chemistry ,Density functional theory ,Physical and Theoretical Chemistry ,0210 nano-technology ,Wave function ,0105 earth and related environmental sciences - Abstract
In this work, ground and excited-state properties were used as descriptors for probing mechanisms as well as to assess potential alternatives for tackling the elimination of perfluorobutane sulfonic acid (PFBS) - C4F9SO2OH, perfluorooctane sulfonic acid (PFOS) - C8F17SO2OH, and perfluorooctanoic acid (PFOA) - C7F15COOH. For this purpose, density functional theory (DFT) and its time-dependent formalism (TD-DFT) at both CAM-B3LYP/6-311+G(2d,2p) and M06-2X/6-311+G(2d,2p) levels of theory in water (IEF-PCM) were employed. To gauge the accuracy of the DFT approaches for the current systems, wave function methods (Moller-Plesset, MP2, coupled-cluster with single and double excitations, CCSD, CCSD with perturbative triples, CCSD(T), and equation of motion CCSD, EOM-CCSD) and aug-cc-pVXZ (X = D and T) basis sets were used. Regarding PFBS and PFOS, all the excited states probed were found to be energetically accessible only in the high-energy vacuum UV region (
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- 2020
49. Insights into the Structural Chemistry of Anhydrous and Hydrous Hexavalent Uranium and Neptunium Dinitrato, Trinitrato, and Tetranitrato Complexes
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Shuao Wang, Gabriel L. Murphy, Eike M. Langer, Evgeny V. Alekseev, Olaf Walter, and Yaxing Wang
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010405 organic chemistry ,Neptunium ,Inorganic chemistry ,chemistry.chemical_element ,Uranium ,010402 general chemistry ,01 natural sciences ,Structural chemistry ,0104 chemical sciences ,Inorganic Chemistry ,chemistry ,Anhydrous ,Physical and Theoretical Chemistry ,Ternary operation - Abstract
A systematic investigation is presented which examines the structural chemistry of anhydrous and hydrous ternary hexavalent uranium and neptunium dinitrato, trinitrato, and tetranitrato complexes. Using slow evaporation methods under acidic conditions the uranium and neptunium nitrate complexes γ-K[UO
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- 2020
50. Nitrogênio e cloreto de mepiquat podem afetar qualidade de fibra e produtividade do algodoeiro
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Aguinaldo J. F. Leal, Gabriel L. Piati, Rafael C. Leite, Mayara S. Zanella, Christian R. W. S. Osorio, and Sebastião F. Lima
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0106 biological sciences ,Environmental Engineering ,Yield (engineering) ,Agriculture (General) ,Harvest time ,chemistry.chemical_element ,Gossypium hirsutum ,Growth regulator ,01 natural sciences ,S1-972 ,Crop ,adubação do algodoeiro ,Animal science ,Mepiquat chloride ,Fiber ,Mathematics ,04 agricultural and veterinary sciences ,Nitrogen ,growth regulator ,chemistry ,regulador de crescimento ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Agronomy and Crop Science ,cotton fertilization ,010606 plant biology & botany - Abstract
The use of mepiquat chloride (MC) in cotton (Gossypium hirsutum L.) cultivation has increased significantly in recent years. The use of MC, a growth regulator, results in higher precocity and lower height and consequently increases yield and reduces crop costs. The objective of this study was to evaluate the effects of nitrogen (N) and MC doses on fiber quality and cotton yield. This study was conducted during the 2012/13 and 2013/14 harvests in the experimental area of the Fundação de Apoio à Pesquisa Agropecuária de Chapadão, located in the municipality of Chapadão do Sul, MS, Brazil, at 18° 48’ 45.9” S, 52° 36’ 3” W, having an altitude of 820 m. The experimental design was a randomized blocks in a 5 × 4 factorial scheme comprised of five N doses (0, 40, 80, 120, 160 kg ha-1) and four MC doses (0, 50, 100, 150 mL ha-1) with four repetitions. Analyses of fiber quality included: length, uniformity, elongation, strength, micronaire index, reflectance, yellowing degrees and short fiber content. Regarding cotton yield, green color index (GCI), plant height at harvest time, and cotton seed yield were determined. The best results for fiber quality and productivity occurr with the application of 76.8 mL ha-1 of MC to the cotton crops when the N dose is greater than 80 kg ha-1. Increasing N doses causes an increase in cotton yield and micronaire index, but there is a decrease in fiber uniformity. RESUMO O uso do cloreto de mepiquat (CM) no cultivo de algodão (Gossypium hirsutum L.) aumentou significativamente nos últimos anos. O uso do CM, um regulador de crescimento, resulta em maior precocidade e menor altura e, consequentemente, aumento da produtividade e redução dos custos da cultura. O objetivo deste estudo foi avaliar os efeitos de doses de nitrogênio e CM sobre a qualidade da fibra e produtividade do algodoeiro. O estudo foi conduzido nas safras 2012/13 e 2013/14, na área experimental da Fundação de Apoio à Pesquisa Agropecuária de Chapadão, em Chapadão do Sul, MS, a 18o 48’ 45,9” S, 52o 36’ 3” W, com altitude de 820 m. O delineamento experimental foi em blocos casualizados em esquema fatorial 5 x 4, correspondendo a cinco doses de N (0, 40, 80, 120, 160 kg ha-1) e quatro doses de CM (0, 50, 100, 150 mL ha-1) com quatro repetições. As avaliações realizadas para análises da qualidade da fibra foram: comprimento, uniformidade, elongação, resistência, índice micronaire, reflectância, graus de amarelecimento e conteúdo de fibras curtas. Para a produtividade do algodão foram feitas análises de índice de cor verde (ICV), altura de plantas no momento da colheita e produtividade do algodão em caroço. Os melhores resultados em qualidade de fibras e produtividade ocorrem com a aplicação de 76,8 mL ha-1 de CM no algodoeiro quando a dose de N é maior que 80 kg ha-1. Doses crescentes de N causam aumento na produtividade de algodão e no índice micronaire, porém há uma diminuição na uniformidade de fibras.
- Published
- 2020
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