21,566 results on '"Reactivity"'
Search Results
2. Experimental investigation on ammonia combustion ignited by methanol-enriched active pre-chamber in an optical engine.
- Author
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Zhang, Yixiao, Mao, Jianshu, Ma, Xiao, Tang, Yong, Wang, Zhi, Wang, Zhenqian, and Shuai, Shijin
- Subjects
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HEAT release rates , *DISTRIBUTION (Probability theory) , *THERMAL efficiency , *JET engines , *FIREFIGHTING , *FLAME , *SPARK ignition engines , *METHANOL as fuel - Abstract
To enhance the ignitability and burning rate of ammonia-fueled spark ignition engines, it is an effective way to adopt active pre-chamber (PC) ignition with high-reactivity fuel. Therefore, in this paper, the ammonia combustion characteristics using methanol-enriched active PC ignition were investigated, based on optical engine experiments with simultaneous in-cylinder flame imaging and pressure measurement. Results show that the overall combustion process is characterized by a three-stage heat release: (I) jet flame controlled combustion; (II) ammonia flame propagation; (III) post jet induced combustion. In stage I, methanol active PC jets with high-momentum and high-reactivity are discharged to ignite MC ammonia mixture, contributing to the first peak of heat release rate. In stage II, ammonia turbulent flame propagation dominates the combustion. In stage III, post jets induce the third peak of heat release rate. In this way, with a minimal methanol energy ratio (ER) of lower than 10 %, stable and fast ammonia combustion is achieved under stoichiometric (λ MC = 1) and lean-burn (λ MC = 1.2) condition, with cyclic variation of indicated mean effective pressure (IMEP) lower than 5 %, flame probability higher than 80 % and maximum global flame speed of about 4 m/s. A highest IEMP of 0.72 MPa and a peak indicated thermal efficiency (η it) of 30 % is obtained at λ MC = 1 and λ MC = 1.2, respectively. However, at the rich limit of λ MC = 0.9 and lean limit of λ MC = 1.4, the quenching of jet flames leads to weak ignition and unstable combustion, which is identified by reduced flame probability distribution and increased cyclic variation of IMEP. In addition, to ensure the cyclic combustion stability, there is also an operating range of methanol ER. At λ MC = 1.2, unstable ignition and deteriorated combustion occur below the lower limit of ER = 6 % and above the upper limit of ER = 17 %. This paper can provide data support and operation strategy for the combustion improvements of ammonia-methanol active jet ignition engines. • Methanol active jet-ignited ammonia combustion in optical engine was studied for the first time. • Ammonia in-cylinder combustion features a three-stage heat release. • Stable and fast ammonia combustion is achieved under stoichiometric and lean-burn conditions. • Jet flame quenching leads to unstable combustion with a reduced flame probability. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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3. Green synthesis and DFT study of orthoaminocarbonitrile methyl tetrahydronaphthalene using WEPA: water extract of pomegranate ash as a sustainable catalyst.
- Author
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Dafale, Pankaj S., Ingale, Vivek S., Gavali, Arati S., Badani, Purav M., and Patil, Kiran N.
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CATALYST synthesis , *CHEMICAL synthesis , *BAND gaps , *POMEGRANATE , *TETRAHYDRONAPHTHALENE - Abstract
Water Extract of Pomegranate Ash (WEPA) emerges as a highly effective green catalyst in the one-pot multicomponent synthesis of orthoaminocarbonitrile tetrahydronaphthalene and its derivatives. The catalyst's utility extends to the novel synthesis of orthoaminocarbonitrile methyltetrahydronaphthalene, achieved through a reaction involving 4-methylcyclohexanone, malononitrile and aromatic aldehydes. The protocol boasts pleasing features including an easy workup procedure, short reaction time, high yield of products (92–96%) and a developed synthesis pathway that circumvents purification processes like chromatography. This research highlights the promising potential of WEPA as a green catalyst in the synthesis of valuable orthoaminocarbonitrile methyltetrahydronaphthalene compounds. Our research provides valuable insights into the stability and reactivity profiles of the derivatives of orthoaminocarbonitrile methyltetrahydronaphthalene through computational studies. DFT studies show that the synthesized compounds exhibit good reactivity, as the band gap of all compounds lies in the range of 4.4 eV. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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4. In Retrospect: Some Peculiarities Observed in the Mechanical Activation of Ground-Granulated Blast Furnace Slag and Fly Ash.
- Author
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Kumar, Rakesh
- Abstract
The focus of this paper is on the mechanical activation of aluminosilicate wastes, namely ground-granulated blast furnace slag (GGBFS) and fly ash (FA). The subject is of relevance to the development of improved blended cements and geopolymers. The presence of large quantities of amorphous phases in these materials makes them unique and challenging from the point of view of characterisation. Interesting findings, some of which were first-time discoveries, are reviewed with emphasis on the role of the milling device (mill type, milling energy, and environment), characterisation challenges, and the manifestation of mechanically induced reactivity. The relative importance of mechanical activation vis-à-vis reaction temperature is highlighted based on calorimetric maps for the geopolymerisation of fly ash. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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5. Age-related differences in metacognitive reactivity in younger and older adults.
- Author
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Murphy, Dillon H., Rhodes, Matthew G., and Castel, Alan D.
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OLDER people ,SEMANTIC memory ,COGNITIVE load ,LEGAL judgments ,METACOGNITION ,MEMORY - Abstract
When we monitor our learning, often measured via judgments of learning (JOLs), this metacognitive process can change what is remembered. For example, prior work has demonstrated that making JOLs enhances memory for related, but not unrelated, word pairs in younger adults. In the current study, we examined potential age-related differences in metacognitive reactivity. Younger and older adults studied lists of related and unrelated word pairs to remember for a later cued recall test where they would be presented with one of the words from the pair and be asked to recall its associate. Additionally, participants either made a JOL for each pair or had an inter-stimulus interval of equal duration as the JOL period. Results revealed that while making metacognitive judgments did not significantly affect memory in younger adults (i.e., no reactivity), this procedure impaired memory in older adults (i.e., negative reactivity), particularly for unrelated word pairs. Specifically, older adults demonstrated better cued recall when each word was followed by an inter-stimulus interval than when asked to predict the likelihood of remembering each word during the study phase. This may be a consequence of JOLs increasing task demands/cognitive load, which could reduce the elaborative encoding of associations between word pairs in older adults, but older adults' preserved or even enhanced semantic memory may mask negative reactivity for related word pairs. Future work is needed to better understand the mechanisms contributing to the reactivity effects in younger and older adults for different types of to-be-remembered information. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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6. Challenges and Performance of Filter Dusts as a Supplementary Cementitious Material.
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Berger, Johannes, Mocciaro, Anabella, Cordoba, Gisela, Martinefsky, Cecilia, Irassar, Edgardo F., Beuntner, Nancy, Scherb, Sebastian, Thienel, Karl-Christian, and Tironi, Alejandra
- Abstract
Global industry relies on a linear approach for economic growth. One step towards transformation is the implementation of a circular economy and the reclamation of anthropogenic deposits. This study examines two filter dusts, one German and one Argentinian, from the production of calcined clays, representing such deposits. Investigations and comparisons of untreated and calcined filter dust and the industrial base product pave the way for using waste product filter dust as supplementary cementitious material (SCM). In the future, some twenty thousand tons of contemporary waste could potentially be used annually as SCM. The results confirm the suitability of one material as a full-fledged SCM without further treatment and a measured pozzolanic reactivity on par with fly ash. Sample materials were classified into two groups: one was found to be a reactive pozzolanic material; the other was characterized as filler material with minor pozzolanic reactivity. Additionally, important insights into the physical properties of oven dust and heat-treated oven dust were obtained. For both material groups, an inversely proportional relationship with rising calcination temperatures was found for the specific surface area and water demand. The impact of the calcination temperature on both the particle size distribution and the potential to optimize the reactivity performance is presented. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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7. Waste Bauxite Residue Valorization as Trace Metal Sorbent: Application to Acid Mine Drainage Remediation.
- Author
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Gauthier, Arnaud, Omana, Brenda, Amin, Fouad, and Le Coustumer, Philipe
- Abstract
With an output of more than two million tons of alumina per year, Venezuela is an important producer. As observed, this mining extraction activity generates a large number of by-products poorly valorized for many reasons (economic, technical, and due to environmental standards and regulations) Venezuela production generates wastes (more than 15 million of m
3 ) called red muds, which are dumped in old lagoons near the Orinoco river or stored. This sludge has a high alkalinity (pH between 10 and 13) and a chemical composition containing some heavy metals (40 ppm Cr, 107 ppm La, 178 ppm Ce) that means it is considered environmentally problematic waste. However, their mineralogical, textural and structural characteristics make them adsorption materials. So, the aim of the study presented here was to investigate the sorption properties of these residues in the case of treatment of water from acid mine drainage. In fact, with an important reactive surface, their capacities to trap by adsorption trace elements such as cadmium, lead or zinc has been studied. Batch sorption tests revealed significant retention of contaminants such as Pb, Zn and As. These retention processes were interpreted using the Langmuir isotherm model. The promising first results indicate that the red mud named Venezuelan bauxite residue (VBR) reveals its great potential as a sorbent of inorganic pollutants. The sorption process is chemically dependent and efficient for certain pH and IS ranges. In addition, the material showed a strong affinity for the adsorption of arsenate (As5+ ). This was observed during post adsorption chemical speciation experiments, through the very high affinity of this element for the least mobile fractions, including oxyhydroxides mobile fractions, including Fe oxyhydroxides (amorphous). Nevertheless, these mining by-products could be considered as valuable absorbent materials. Despite this promising results, further studies are required to evaluate their potential in different conditions (dynamic tests, pH, IS, inorganic and organic contaminants, concentration and time effect). [ABSTRACT FROM AUTHOR]- Published
- 2024
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8. Gas-Phase Characterization of Redox-Active Manganese Complexes.
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Huber, Maximilian E., Ceman, Adela, Weber, Philipp, Berg, Lisa, East, Nathan R., Riehn, Christoph, Heinze, Katja, and Meyer, Jennifer
- Abstract
Manganese complexes exhibit a rich redox chemistry, usually accompanied by structural reorganization during the redox processes often followed by ligand dissociation or association. The push–pull ligand 2,6-diguanidylpyridine (dgpy) stabilizes manganese in the oxidation states +II, +III, and + IV in the complexes [Mn-(dgpy)2]n+ (n = 2–4) without change in the coordination sphere in the condensed phase [Heinze et al., Inorganic Chemistry, 2022, 61, 14616]. In the condensed phase, the manganese-(IV) complex is a very strong oxidant. In the present work, we investigate the stability and redox activity of the MnIV complex and its counterion (PF6–) adducts in the gas phase, using two modified 3D Paul ion trap mass spectrometers. Six different cationic species of the type [Mnx(dgpy)2(PF6)y]n+ (x = II, III, IV, y = 0–3, n = 1–3) could be observed for the three oxidation states MnIV, MnIII, and MnII, of which one observed complex also contains a reduced dgpy ligand. MnII species showed the highest relative stability in collision induced dissociation and UV/vis photo dissociation experiments. The lowest stability is observed in the presence of one or more counterions, which correlates to a lower total charge n+. Gas phase UV/vis spectra show similar features as the condensed phase spectra only differing in relative band intensities. The strongly oxidizing MnIV complex reacts with triethylamine (NEt3) in the gas phase to give MnIII, while MnIII species show little reactivity toward NEt3. [ABSTRACT FROM AUTHOR]
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- 2024
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9. Heterogeneous Catalysis in the Synthesis of Nitrogen‐Containing Heterocyclics.
- Author
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Rajendran, Arsha, Anand, Samika, Sunajadevi, Kalathiparambil Rajendra Pai, Pinheiro, Dephan, and Chundattu, Sony J.
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SUSTAINABLE chemistry , *HETEROGENEOUS catalysis , *HETEROGENEOUS catalysts , *HETEROCYCLIC compounds synthesis , *HOMOGENEOUS catalysis - Abstract
The synthesis of nitrogen‐containing heterocyclic compounds using heterogeneous catalysis is a topic of significant interest in organic synthesis and chemical research. Heterogeneous catalysis offers several advantages over homogeneous catalysis, including easier separation and recovery of the catalyst, reduced waste generation, and potentially higher stability and reusability. In this review, the pivotal role of heterogeneous catalysis in synthesizing nitrogen‐containing heterocyclic compounds is explored. Various types of heterocycles and the specific applications of these compounds in drug discovery and material development are discussed in detail. This review discusses various examples of heterogeneous catalysts employed in the synthesis of nitrogen‐containing heterocycles, including metal oxides, supported metals, metal nanoparticles, zeolites, and other porous materials. Emphasis is placed on the mechanistic insights and reaction pathways facilitated by different catalysts. Additionally, recent advancements and innovations in the field are discussed, including novel catalyst designs, green chemistry approaches, and emerging trends in catalytic materials. The aim is to provide a comprehensive overview of the impact and potential of heterogeneous catalysis in this important area of organic synthesis. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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10. Study of the microstructure of special types of coke from Kazakhstan.
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Ulyeva, G. A. and Volokitina, I. E.
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COKE (Coal product) , *REDUCING agents , *MANUFACTURING processes , *COAL , *COAL carbonization - Abstract
This article presents an overview of the technology employed in the production of special types of coke obtained from non-sintering coals sourced from Kazakhstan. The microstructure of special types of coke is elucidated, and the effect of the heating rate on their microstructure and properties essential for use as a reducing agent in electrothermal processes for the production of technical silicon metal is studied. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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11. Tuning a bioengineered hydrogel for studying astrocyte reactivity in glioblastoma.
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DePalma, Thomas J., Hisey, Colin L., Hughes, Kennedy, Fraas, David, Tawfik, Marie, Scharenberg, Jason, Wiggins, Sydney, Nguyen, Kim Truc, Hansford, Derek J., Reátegui, Eduardo, and Skardal, Aleksander
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ASTROCYTOMAS ,EXTRACELLULAR vesicles ,CENTRAL nervous system ,BRAIN cancer ,BRAIN diseases - Abstract
Astrocytes play many essential roles in the central nervous system (CNS) and are altered significantly in disease. These reactive astrocytes contribute to neuroinflammation and disease progression in many pathologies, including glioblastoma (GB), an aggressive form of brain cancer. Current in vitro platforms do not allow for accurate modeling of reactive astrocytes. In this study, we sought to engineer a simple bioengineered hydrogel platform that would support the growth of primary human astrocytes and allow for accurate analysis of various reactive states. After validating this platform using morphological analysis and qPCR, we then used the platform to begin investigating how astrocytes respond to GB derived extracellular vesicles (EVs) and soluble factors (SF). These studies reveal that EVs and SFs induce distinct astrocytic states. In future studies, this platform can be used to study how astrocytes transform the tumor microenvironment in GB and other diseases of the CNS. Recent work has shown that astrocytes help maintain brain homeostasis and may contribute to disease progression in diseases such as glioblastoma (GB), a deadly primary brain cancer. In vitro models allow researchers to study basic mechanisms of astrocyte biology in healthy and diseased conditions, however current in vitro systems do not accurately mimic the native brain microenvironment. In this study, we show that our hydrogel system supports primary human astrocyte culture with an accurate phenotype and allows us to study how astrocytes change in response to a variety of inflammatory signals in GB. This platform could be used further investigate astrocyte behavior and possible therapeutics that target reactive astrocytes in GB and other brain diseases. [Display omitted] [ABSTRACT FROM AUTHOR]
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- 2024
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12. The dimer effect: A refinement approach towards skin sensitization assessment in‐chemico using Amino acid Derivative Reactivity Assay.
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Paul Choudhury, Ratnadeep, Singh, Akanksha, Mathai, Eldho, Sudhakar, DGS, Tourneix, Fleur, Alépée, Nathalie, and Gautier, Francoise
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AMINO acid derivatives ,CHEMICAL testing ,ALLERGENS ,PEPTIDES ,SULFHYDRYL group - Abstract
Skin sensitization is a key endpoint for safety assessment, especially for cosmetics and personal care products. The adverse outcome pathway for skin sensitization and the chemical and biological events driving the induction of human skin sensitization are now well understood. Several non‐animal test methods have been developed to predict sensitizer potential by measuring the impact of chemical sensitizers on these key events. In this work, we have focused on Key Event 1 (the molecular initiating step), which is based on formation of a covalent adduct between skin sensitizers and endogenous proteins and/or peptides in the skin. There exists three in‐chemico assays approved by the Organization for Economic Co‐operation and Development—(1) Direct Peptide Reactivity Assay (DPRA), (2) Amino Acid Derivative Reactivity Assay (ADRA), and (3) Kinetic Direct Peptide Reactivity Assay (kDPRA) to quantify peptide/amino acid derivative depletion after incubation with test chemicals. However, overestimated depletion of the cysteine‐based peptide/amino acid derivatives is known in such assays because of the dimerization of the thiol group. In this present work, we report the synthesis and structural confirmation of the dimer of N‐(2‐[1‐naphthyl]acetyl)‐L‐cysteine (NAC) from the ADRA assay to allow simultaneous determination of (a) peptide depletion by quantifying NAC monomer and (b) peptide dimerization by quantifying NAC dimer thereby eliminating the overestimation. We present a case study with three chemicals to demonstrate the importance of this approach. Thus, this simultaneous assay gives a more informed view of the peptide reactivity of chemicals to better identify skin sensitizers. Guidelines for skin sensitization addressing Key Event 1 include three in‐chemico methods: DPRA, ADRA, and kDPRA. However, overestimated depletion of the Cysteine‐based peptide/amino acid derivatives is known in such assays because of the dimerization of the thiol group. In this present work, we synthesized NAC dimer from the ADRA assay to allow simultaneous determination of peptide depletion and dimerization, thus eliminating the overestimation. We present a case study with three chemicals to demonstrate the importance of this approach. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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13. The “Imperceptibly Narrowing Diamond” Generation—Adaptation Strategies of the Generation X Representatives Toward Their Old Age.
- Author
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Kramkowska, Emilia and Korzeniecka-Bondar, Alicja
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Population aging is becoming one of society’s priority issues. An assumption is that it is beneficial (the benefits for the individual and society are shown in the text) for people currently of working age (representatives of Generation X) to anticipate their old age. In this article, the results of a qualitative study are presented. The aim is to identify the adaptation strategies of representatives of Generation X toward their old age. The theoretical basis was set by reflections on generations, enriched by the metaphor of the “imperceptibly narrowing diamond.” The data collection method was an unstructured interview with a standardized list of information sought, conducted with ten people (with higher education) from Generation X. As a result of the thematic analysis, two adaptation strategies toward old age emerged for the representatives of Generation X: proactive and reactive. [ABSTRACT FROM AUTHOR]
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- 2024
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14. Regulating Peripheral Nitrogen Dopants in Single‐Atom Catalysts to Enhance Propane Dehydrogenation.
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Wei, Fenfei, Cao, Liru, Ge, Bingqing, Chen, Yang, Pan, Xiaoli, Chai, Yicong, Jing, Rizheng, Hu, Xixi, Wang, Xiaodong, Lin, Jian, and Lin, Sen
- Abstract
For single‐atom catalysts (SACs), the dopants situated near the metal site have demonstrated a significant impact on the catalytic properties. However, the effect of dopants situated further away from the metal centers and their working mechanisms remain to be elucidated. Herein, we conduct density functional theory‐driven studies on regulating the peripheral nitrogen dopants in graphene‐based SACs, with a particular focus on Ir1 SAC, for propane dehydrogenation (PDH). It is found that increasing the distance between the N dopant and the Ir1 site results in a different energy change for the reaction process compared to the dense doping models with only first and second‐shell N species. The proposed stochastic doping models demonstrate statistically that increasing the N dopant in farther shells not only enhances the activity of Ir1 but also maintains a high selectivity for propene, which is verified by experimental tests. The modulation of the
d ‐band center of Ir1 by stochastic N dopants effectively modifies the binding strength of reaction intermediates, thereby enabling the optimization of the potential energy surface of PDH. These results deepen the understanding of dopant states around metal sites and provide an important implication for the doping engineering in heterogeneous catalysis. [ABSTRACT FROM AUTHOR]- Published
- 2024
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15. Exohedral Diels‐Alder Reactivity of Endohedral Metallofullerene C36.
- Author
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Santha Bhaskaran, Athul, Romero del Blanco, Dani, Romero‐Rivera, Adrià, Osuna, Sílvia, and Swart, Marcel
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DENSITY functional theory , *ORBITAL interaction , *DIELS-Alder reaction , *METALLOFULLERENES , *METAL ions - Abstract
Understanding the exohedral reactivity of metallofullerenes is crucial for its application in various fields. By systematically controlling the trapped species inside the fullerene its reactivity can be tamed. In this work we report the preferential position of 3d metal atoms inside the C36 cage and their effect on exohedral reactivity in comparison with the neutral and the dianionic cage. The Diels‐Alder (DA) reaction between butadiene and all non‐equivalent [5‐5], [6‐5] and [6‐6] C−C bonds on the fullerene cage was considered for the analysis, by using density functional theory at the S12g/TZ2P level including COSMO solvation model to elucidate the complete mechanistic pathways. Our results indicate that the preferential position of the metal ion is at the position close to the upper hexagon, and that the general trend in the reactivity of bonds follows the order [5‐5]>[6‐5]>[6‐6]. Moreover, the encapsulation of metal atoms further enhances the reactivity of these bonds, by lowering the LUMOs of the cage, hence maximizing the orbital interactions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
16. Exohedral Diels‐Alder Reactivity of Endohedral Metallofullerene C36.
- Author
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Santha Bhaskaran, Athul, Romero del Blanco, Dani, Romero‐Rivera, Adrià, Osuna, Sílvia, and Swart, Marcel
- Subjects
DENSITY functional theory ,ORBITAL interaction ,DIELS-Alder reaction ,METALLOFULLERENES ,METAL ions - Abstract
Understanding the exohedral reactivity of metallofullerenes is crucial for its application in various fields. By systematically controlling the trapped species inside the fullerene its reactivity can be tamed. In this work we report the preferential position of 3d metal atoms inside the C36 cage and their effect on exohedral reactivity in comparison with the neutral and the dianionic cage. The Diels‐Alder (DA) reaction between butadiene and all non‐equivalent [5‐5], [6‐5] and [6‐6] C−C bonds on the fullerene cage was considered for the analysis, by using density functional theory at the S12g/TZ2P level including COSMO solvation model to elucidate the complete mechanistic pathways. Our results indicate that the preferential position of the metal ion is at the position close to the upper hexagon, and that the general trend in the reactivity of bonds follows the order [5‐5]>[6‐5]>[6‐6]. Moreover, the encapsulation of metal atoms further enhances the reactivity of these bonds, by lowering the LUMOs of the cage, hence maximizing the orbital interactions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
17. Changes in Cx43 and AQP4 Proteins, and the Capture of 3 kDa Dextran in Subpial Astrocytes of the Rat Medial Prefrontal Cortex after Both Sham Surgery and Sciatic Nerve Injury.
- Author
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Bretová, Karolína, Svobodová, Viktorie, and Dubový, Petr
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SCIATIC nerve injuries , *NERVOUS system injuries , *SCIATIC nerve , *PREFRONTAL cortex , *CEREBROSPINAL fluid - Abstract
A subpopulation of astrocytes on the brain's surface, known as subpial astrocytes, constitutes the "glia limitans superficialis" (GLS), which is an interface between the brain parenchyma and the cerebrospinal fluid (CSF) in the subpial space. Changes in connexin-43 (Cx43) and aquaporin-4 (AQP4) proteins in subpial astrocytes were examined in the medial prefrontal cortex at postoperative day 1, 3, 7, 14, and 21 after sham operation and sciatic nerve compression (SNC). In addition, we tested the altered uptake of TRITC-conjugated 3 kDa dextran by reactive subpial astrocytes. Cellular immunofluorescence (IF) detection and image analysis were used to examine changes in Cx43 and AQP4 protein levels, as well as TRITC-conjugated 3 kDa dextran, in subpial astrocytes. The intensity of Cx43-IF was significantly increased, but AQP4-IF decreased in subpial astrocytes of sham- and SNC-operated rats during all survival periods compared to naïve controls. Similarly, the uptake of 3 kDa dextran in the GLS was reduced following both sham and SNC operations. The results suggest that both sciatic nerve injury and peripheral tissue injury alone can induce changes in subpial astrocytes related to the spread of their reactivity across the cortical surface mediated by increased amounts of gap junctions. At the same time, water transport and solute uptake were impaired in subpial astrocytes. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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18. Age differences in emotional reactivity to facets of sadness and anger.
- Author
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Muskin, Ryan M. and Allard, Eric S.
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AGE differences , *YOUNG adults , *OLDER people , *OLD age , *EMOTIONS , *SADNESS - Abstract
Emotional reactivity, based on the discrete emotions approach (DEA), is related to opportunities or constraints across development. While prior research suggests sadness to be more adaptive in old age and anger to be more adaptive in young adulthood, there may be facets within these discrete emotion categories that further expand the DEA framework: loss-based vs. failure-based sadness and frustration-based vs. moral violation-based anger. A sample of 49 younger adults (
M age = 20.00,SD = 2.26) and 51 older adults (M age = 66.00,SD = 4.94) were asked to relive and describe an emotional memory associated with facets of sadness and anger. Emotional reactivity was operationalized through self-report ratings on distinct facet categories. Results revealed a significant age difference in emotional reactivity to moral violation-based anger, with older adults being more reactive than younger adults. No other significant age differences were observed. These findings are discussed in terms of how further distinctions across emotional facets can inform a better understanding of affective experience across adulthood and old age. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
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19. Histone deacetylase inhibition mitigates cognitive deficits and astrocyte dysfunction induced by amyloid‐β (Aβ) oligomers.
- Author
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Diniz, Luan Pereira, Morgado, Juliana, Bergamo Araujo, Ana Paula, da Silva Antônio, Leticia Maria, Mota‐Araujo, Hannah Paola, de Sena Murteira Pinheiro, Pedro, Sagrillo, Fernanda Savacini, Cesar, Gabriele Vargas, Ferreira, Sérgio T., Figueiredo, Cláudia Pinto, Manssour Fraga, Carlos Alberto, and Gomes, Flávia Carvalho Alcantara
- Subjects
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ALZHEIMER'S disease , *HISTONE deacetylase inhibitors , *HISTONE deacetylase , *NEURODEGENERATION , *WESTERN immunoblotting - Abstract
Background and Purpose: Inhibitors of histone deacetylases (iHDACs) are promising drugs for neurodegenerative diseases. We have evaluated the therapeutic potential of the new iHDAC LASSBio‐1911 in Aβ oligomer (AβO) toxicity models and astrocytes, key players in neuroinflammation and Alzheimer's disease (AD). Experimental Approach: Astrocyte phenotype and synapse density were evaluated by flow cytometry, Western blotting, immunofluorescence and qPCR, in vitro and in mice. Cognitive function was evaluated by behavioural assays using a mouse model of intracerebroventricular infusion of AβO. Key Results: LASSBio‐1911 modulates reactivity and synaptogenic potential of cultured astrocytes and improves synaptic markers in cultured neurons and in mice. It prevents AβO‐triggered astrocytic reactivity in mice and enhances the neuroprotective potential of astrocytes. LASSBio‐1911 improves behavioural performance and rescues synaptic and memory function in AβO‐infused mice. Conclusion and Implications: These results contribute to unveiling the mechanisms underlying astrocyte role in AD and provide the rationale for using astrocytes as targets to new drugs for AD. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
20. How biotic interactions structure species' responses to perturbations.
- Author
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Lajaaiti, Ismaël, Kéfi, Sonia, and Arnoldi, Jean-François
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BIOTIC communities , *ENDANGERED species , *POPULATION dynamics , *ECOLOGICAL models , *SPECIES - Abstract
Predicting how ecological communities will respond to disturbances is notoriously challenging, especially given the variability in species' responses within the same community. Focusing solely on aggregate responses may obscure extinction risks for certain species owing to compensatory effects, emphasizing the need to understand the drivers of the response variability at the species level. Yet, these drivers remain poorly understood. Here, we reveal that despite the typical complexity of biotic interaction networks, species' responses follow a discernible pattern. Specifically, we demonstrate that the species whose population abundances are most reduced by biotic interactions—which are not always the rarest species—are those that exhibit the strongest responses to disturbances. This insight enables us to pinpoint sensitive species within communities without requiring precise information about biotic interactions. Our novel approach introduces avenues for future research aimed at identifying sensitive species and elucidating their impacts on entire communities. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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21. Recent advances in oxidative dehydrogenation of propane to propylene on boron-based catalysts.
- Author
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Jiang, Xiao, Zhang, Ke, Forte, Michael J., Cao, Sufeng, Hanna, Brian S., and Wu, Zili
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REACTION mechanisms (Chemistry) , *OXIDATIVE dehydrogenation , *BORON nitride , *TRANSITION metal oxides , *GAS phase reactions - Abstract
Oxygen-assisted oxidative dehydrogenation of propane (O2-ODHP) to propylene is a promising route that complements the existing oil-based processes to bridge the gap between continuously increasing market demand and productivity of propylene. This reaction i) is free from thermodynamic constraint and ii) features minimized coke deposition of the catalyst. A major challenge of ODHP lies in the over-oxidation to undesired carbon oxides (COx). Transition metal oxides have been extensively explored in the past decades; however, they suffer from a low olefin selectivity. Most recently, hexagonal boron nitride (h-BN) emergesas a promising candidate for ODHP, which shows a unique high selectivity toward light olefins (C2-C3) and negligible COx formation. To interpret the origin of such unique catalytic performance, significant efforts have been put forth in identifying active sites and developing an in-depth understanding of reaction mechanisms through combined experimental and computational approaches. In general, boron-oxide species are identified as the active sites, and a surface-induced gas-phase reaction mechanism has been proposed, though detailed scenarios vary. These findings explain the Eley-Rideal kinetic behavior and unique high olefin selectivity of h-BN. The breakthrough in h-BN catalysts revitalizes the exploration of boron-oxide catalysts because of their identical kinetic behavior and similar active sites to h-BN catalysts. With the accumulated knowledge, continuous endeavor is devoted to developing advanced boron-containing materials for enhanced activity and durability. This review aims to summarize the recent advances in ODHP on boron-based catalysts, with particular emphases on catalytic performance, kinetic behavior, stability and leaching issues, identification of active sites, and site-dependent reaction mechanisms, as well as the development of advanced boron-based materials. With this review, we expect to not only provide an overview to keep abreast of the state-of-the-art boron-containing catalytic materials for ODHP, but also to identify key descriptors for designing efficient boron-based catalysts with low-temperature activity. TOC: [ABSTRACT FROM AUTHOR]
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- 2024
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22. On the link between the reaction force constant and conceptual DFT.
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Cárdenas, Carlos, Ayers, Paul W., Chakraborty, Debajit, Gómez, Tatiana, Echeverri, Andrea, Munoz, Francisco, and Fuentealba, Patricio
- Subjects
- *
PROTON transfer reactions , *MOLECULAR force constants , *REACTION forces , *CHEMICAL potential , *DENSITY functional theory - Abstract
Context: The reaction force constant (κ ), introduced by Professor Alejandro Toro-Labbé, plays a pivotal role in characterizing the reaction pathway by assessing the curvature of the potential energy profile along the intrinsic reaction coordinate. This study establishes a novel link between κ and the reactivity descriptors of conceptual density functional theory (c-DFT). Specifically, we derive expressions that relate the reaction force constant to nuclear softness and variations in chemical potential. Our findings indicate that regions of the reaction pathway where κ is negative match with significant electronic structure rearrangements, while positive κ regions match mostly with geometric rearrangements. This correlation between κ and c-DFT reactivity descriptors enhances our understanding of the underlying forces driving chemical reactions and offers new perspectives for analyzing reaction mechanisms. Methods: The internal reaction path for the proton transfer in SNOH, chemical potential, and nuclear softness were computed using DFT with B3LYP exchange-correlation functional and 6-311++G(d,2p) basis set. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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23. Maternal behavior scores and temperament of ewes under intensive and extensive handling systems.
- Author
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da Porciuncula, Gabriela Caillava, Aita, Marta Farias, Werncke, Daíse, Bettencourt, Arthur Fernandes, Poli, César Henrique Espírito Candal, and Fischer, Vivian
- Subjects
- *
HUMAN-animal relationships , *ANIMAL welfare , *PRINCIPAL components analysis , *FACTOR analysis , *EWES , *ANIMAL weaning , *LOGISTIC regression analysis - Abstract
Maternal behavior has been related to ewe's reactivity, as more reactive ewes might have greater risk of presenting worse maternal ability. This study aimed to determine the association between maternal behavior score (MBS) of Corriedale ewes with their physiological and behavioral variables measured at weaning of their offspring within two handling systems. Data from 335 ewes with average (± SE) age of 3.1 ± 1.8 years and 46.5 ± 6.1 kg of body weight were used. Experimental farms were classified into two handling systems: intensive (n = 3) and extensive (n = 2), based on stocking density and nature of human-animal relationships. Maternal behavior was evaluated in the field within 24 h after delivery, using a 6-rated scale (1 = poor to 6 = excellent). This scale takes into account the distance the ewe takes from the lamb when the lamb is restrained by an observer. The temperament of the ewes was evaluated during an arena test, at the weaning of the lambs, and was divided into two phases: social isolation and human presence. Data were subjected to principal component analysis and logistic regression. Logistic regression of principal factor (PF) scores in MBS showed that physical activity during the isolation phase increased in 1.57 (CI: 1.02 to 2.42; P < 0.05) the probability of extensively handling ewes showing high MBS (≥4), while in intensively handling ewes, logistic regression showed that the number of vocalizations in both phases of the arena test increased in 1.64 (CI: 1.12 to 2.4; P < 0.05) the probability of ewes having high MBS. Albeit the handling systems are not comparable, MBS was positively associated with some behavioral variables measured at the arena test. [ABSTRACT FROM AUTHOR]
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- 2024
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24. Allochthonous dissolved organic matter sources: effect of photodegradation on leaf leachates of invasive and native species from an Andean Patagonia catchment.
- Author
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Soto Cárdenas, Carolina, Garcia, R. Daniel, and Garcia, Patricia E.
- Subjects
- *
CARBON content of water , *DISSOLVED organic matter , *NATIVE species , *LODGEPOLE pine , *BODIES of water - Abstract
The vegetation surrounding aquatic ecosystems contributes allochthonous sources of organic matter to the water bodies. In Andean-Patagonian catchments, several non-native species grow among native ones. Different sources of dissolved organic matter (DOM) may vary in their contribution, potentially affecting aquatic functioning. This study evaluates differences in DOM contributions from native and non-native plants, analyzing DOM reactivity through its optical properties. An outdoor experiment was conducted with DOM leaf leachates from two native (Maytenus boaria and Nothofagus dombeyi) and two invasive trees (Salix fragilis and Pinus contorta). We characterized DOM concentration and quality optically by UV–Visible and fluorescence spectroscopy and found differences in both quantity and quality between the different leaf leachates. The exotic S. fragilis presented up to 7 times higher dissolved organic carbon (DOC) values than the other species. We found that leachates response to light exposure depended on its DOM composition. Decreasing patterns of DOC absorbance and fluorescence were observed in all leachates over time. We detected a gradient in leaf leachate photoreactivity due to solar exposure: (S. fragilis > P. contorta > M. boaria = N. dombeyi). Overall, our work shows that the invasive plants studied produce larger amounts of degradable DOM than some local native species. [ABSTRACT FROM AUTHOR]
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- 2024
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25. Sulfotransferase‐mediated phase II drug metabolism prediction of substrates and sites using accessibility and reactivity‐based algorithms.
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Vyas, Shivam Kumar, Das, Avik, Suryanarayana Murty, Upadhyayula, and Dixit, Vaibhav A.
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MACHINE learning ,DRUG discovery ,DRUG accessibility ,WARNING labels ,SULFOTRANSFERASES ,DRUG metabolism - Abstract
Sulphotransferases (SULTs) are a major phase II metabolic enzyme class contributing ~20 % to the Phase II metabolism of FDA‐approved drugs. Ignoring the potential for SULT‐mediated metabolism leaves a strong potential for drug‐drug interactions, often causing late‐stage drug discovery failures or black‐boxed warnings on FDA labels. The existing models use only accessibility descriptors and machine learning (ML) methods for class and site of sulfonation (SOS) predictions for SULT. In this study, a variety of accessibility, reactivity, and hybrid models and algorithms have been developed to make accurate substrate and SOS predictions. Unlike the literature models, reactivity parameters for the aliphatic or aromatic hydroxyl groups (R/Ar−O−H), the Bond Dissociation Energy (BDE) gave accurate models with a True Positive Rate (TPR)=0.84 for SOS predictions. We offer mechanistic insights to explain these novel findings that are not recognized in the literature. The accessibility parameters like the ratio of Chemgauss4 Score (CGS) and Molecular Weight (MW) CGS/MW and distance from cofactor (Dis) were essential for class predictions and showed TPR=0.72. Substrates consistently had lower BDE, Dis, and CGS/MW than non‐substrates. Hybrid models also performed acceptablely for SOS predictions. Using the best models, Algorithms gave an acceptable performance in class prediction: TPR=0.62, False Positive Rate (FPR)=0.24, Balanced accuracy (BA)=0.69, and SOS prediction: TPR=0.98, FPR=0.60, and BA=0.69. A rule‐based method was added to improve the predictive performance, which improved the algorithm TPR, FPR, and BA. Validation using an external dataset of drug‐like compounds gave class prediction: TPR=0.67, FPR=0.00, and SOS prediction: TPR=0.80 and FPR=0.44 for the best Algorithm. Comparisons with standard ML models also show that our algorithm shows higher predictive performance for classification on external datasets. Overall, these models and algorithms (SOS predictor) give accurate substrate class and site (SOS) predictions for SULT‐mediated Phase II metabolism and will be valuable to the drug discovery community in academia and industry. The SOS predictor is freely available for academic/non‐profit research via the GitHub link. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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26. Balancing: A solution to our distorted indices of transient dynamics.
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Hinrichsen, Richard A.
- Subjects
TRANSIENTS (Dynamics) ,POPULATION forecasting ,POPULATION dynamics ,PSEUDOSPECTRUM ,LIFTING & carrying (Human mechanics) - Abstract
Because populations are at the mercy of random disturbances large and small, they rarely, if ever, converge on predicted long‐term behaviors. Therefore, when employing matrix population models, ecologists study the dynamics of populations that depart from stable distributions. Necessary for such studies are indices of transient dynamics that measure the size of short‐term population fluctuations. These indices advance our understanding of population dynamics by revealing that population growth rate in a single timestep can far exceed the stable population growth rate. Despite their value, indices of transient behavior possess two major shortcomings: they are scale dependent and easily distorted by outsized population classes. Distortion occurs whenever immature classes, due to their sheer size, carry greater weight in the calculation of population size than mature classes. Beluga sturgeon (Huso huso), for example, have an immature age class (eggs) that is several orders of magnitude larger than its mature age classes. To remove the undue influence of outsized classes, I use balancing, which rescales classes by the stable population distribution and makes the indices of transient dynamics scale invariant. I apply balancing to 1800 population projection matrices for various species across the Animal Kingdom, using reactivity and the Henrici metric of non‐normality as indices of transient dynamics. I found that balancing profoundly changes the picture of which populations have the greatest or least potential transient dynamics. Using a population projection matrix for northern pike (Esox lucius), I demonstrate how balancing influences pseudospectra contour plots that are used to infer transient dynamics. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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27. Regulation of Reactivity of Calcined Ultrafine Kaolin Products.
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Yin, Hui, Liu, Huajie, Bu, Yuhuan, Chen, Weiqing, Ding, Fuquan, Lin, Wenxiang, and Zhang, Yuwei
- Subjects
PARTICLE analysis ,X-ray diffraction ,THERMAL expansion ,CONSTRUCTION materials ,RAW materials ,KAOLIN - Abstract
This study explored the potential of ultrafine kaolin as a geopolymer raw material, focusing on the reactivity of calcined kaolin products and its influencing factors. Through a series of analytical techniques, including thickening experiments, particle size analysis, SEM, XRD, and FT-IR, the effects of calcination temperature, time, and Si-Al ratio were evaluated. The results indicated that calcination temperature significantly impacts reactivity, with optimal conditions found between 600 °C and 800 °C, yielding metakaolin with thickening times of 12 to 43 min. Temperatures above 900 °C led to the formation of low-reactivity phases like mullite. The Si-Al ratio also influenced thickening time, with durations varying from 97 min at 0.85 to 43 min at 0.9 and increasing to 157 min at 0.95. Calcination time had the smallest effect, with thickening times ranging from 10 to 25 min over 4 to 8 h. Additionally, calcination altered particle size, initially expanding due to thermal expansion and later shrinking due to lattice distortion above 700 °C. By adjusting these parameters, the reactivity of calcined kaolin could be tailored to suit specific needs. This research provides a theoretical foundation for metakaolin's application in construction materials and offers novel insights into geopolymer preparation. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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28. Synthesis and theoretical study of the stability and reactivity of some 2-[(benzimidazolyl)methylthio]-4,5-diphenylimidazole derivatives using the density functional theory (DFT) method.
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COULIBALY, Bamoro, DIOMANDE, Se kou, SANGARE, Kassoum, ABLE, Anoh Valentin, Aurélie, Vallin, and FANTE, Bamba
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DENSITY functional theory ,MOLECULAR orbitals ,ELECTRIC potential ,BAND gaps ,IMIDAZOLES - Abstract
The stability and reactivity of the five (5) 2-[(benzimidazolyl)methylthio]-4,5- diphenylimidazole derivatives were studied using density functional theory at the B3LYP/6-31+ G (d, p) level. Analysis of the molecular electrostatic potential (MEP) map and determination of the dual descriptor showed that nitrogen N13, sulfur S5 and carbons C19 and C21 are nucleophilic. They are therefore susceptible to electrophilic attack. The nitrogens N2, N3 and N14 are shared between electrophilic and nucleophilic sites. The study of the chemical reactivity of our compounds was carried out based on the analysis of molecular frontier orbitals (HOMO and LUMO), energy gap (Δε), chemical hardness (η), electrophilicity (ω) and chemical softness (S). Compound 1 was found to be the most stable, the least reactive and electron-donating. This study also opens up a new way of synthesizing biologically active molecules by modulating the C19 carbon with inductive electroattractant groups. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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29. Emission characteristics, environmental impacts and health risk assessment of volatile organic compounds from the typical chemical industry in China.
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Chen, Kaitao, Gu, Xin, Cai, Min, Zhao, Weicheng, Wang, Boxuan, Yang, Haoran, Liu, Xingang, and Li, Xingru
- Subjects
- *
VOLATILE organic compounds , *CHEMICAL industry , *HEALTH impact assessment , *PESTICIDES industry , *ORGANIC compounds , *HEALTH risk assessment - Abstract
To study the volatile organic compounds (VOCs) emission characteristics of industrial enterprises in China, 6 typical chemical industries in Yuncheng City were selected as research objects, including the modern coal chemical industry (MCC), pharmaceutical industry (PM), pesticide industry (PE), coking industry (CO) and organic chemical industry (OC). The chemical composition of 91 VOCs was quantitatively analyzed. The results showed that the emission concentration of VOCs in the chemical industry ranged from 1.16 to 155.59 mg/m3. Alkanes were the main emission components of MCC (62.0%), PE (55.1%), and OC (58.5%). Alkenes (46.5%) were important components of PM, followed by alkanes (23.8%) and oxygenated volatile organic compounds (OVOCs) (21.2%). Halocarbons (8.6%-71.1%), OVOCs (9.7%-37.6%) and alkanes (11.2%-27.0%) were characteristic components of CO. The largest contributor to OFP was alkenes (0.6%-81.7%), followed by alkanes (9.3%-45.9%), and the lowest one was alkyne (0%-0.5%). Aromatics (66.9%-85.4%) were the largest contributing components to SOA generation, followed by alkanes (2.6%-28.5%), and the lowest one was alkenes (0%-4.1%). Ethylene and BTEX were the key active species in various chemical industries. The human health risk assessment showed workers long-term exposed to the air in the chemical industrial zone had a high cancer and non-cancer risk during work, and BTEX and dichloromethane were the largest contributors. [ABSTRACT FROM AUTHOR]
- Published
- 2025
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30. Synthesis and reactivity of the di(9-anthryl)methyl radical
- Author
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Tomohiko Nishiuchi, Kazuma Takahashi, Yuta Makihara, and Takashi Kubo
- Subjects
anthracene ,cation ,dimerization ,radical ,reactivity ,Science ,Organic chemistry ,QD241-441 - Abstract
The di(9-anthryl)methyl (DAntM) radical was synthesized and investigated to elucidate its optical, electrical properties, and reactivity. The generation of the DAntM radical was confirmed by its ESR spectrum, which showed two broad signals. The unpaired electron is primarily localized on the central sp2 carbon and slightly delocalized over the two anthryl moieties. Although the DAntM radical undergoes dimerization in solution, the radical still remains even at 190 K due to the bulky nature of the two anthryl groups. Interestingly, upon exposure to air, the purple color of the radical solution quickly fades to orange, resulting in decomposition to give 9-anthryl aldehyde and anthroxyl radical derivatives.
- Published
- 2024
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31. Relationship between Sensory Processing Sensitivity and Personality Traits
- Author
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Tayfun Özpek and Fatma Kandemir
- Subjects
sensory processing sensitivity ,five factor theory of personality ,reactivity ,personality traits ,Psychiatry ,RC435-571 - Abstract
Reactions to stimuli vary from person to person. The same stimulus has different effects depending on the perception of different people and the physical and mental states they are in. Considering this difference, situations can be seen in which a person perceives a specific stimulus or group of stimuli as negative and disturbing for themselves. In particular, people with high levels of sensory processing sensitivity feel the negative effects of stimuli more intensely both in terms of their internal processes (hunger, pain, sadness, stress, etc.) and the situation of the physical environment (loud noise, bright light, pungent odor, etc.) which they are in. On the other hand, the existence of situations where sensory processing sensitivity has a positive effect is also noticeable. In this context, the relationship between sensory processing sensitivity and personality traits is examined. The concept of personality is explained in different ways by many different theorists in the international literature. In order to avoid confusion that may arise in the definition and understanding of personality traits, in this review study, personality traits are examined on the basis of the Five Factor Personality Theory. Within the framework of the personality definition of the Five Factor Personality Theory, The relationship between five basic personality traits and sensory processing sensitivity is examined by also considering the subdimensions of each five personality traits.
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- 2024
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32. Study of synergistic behavior during bituminous coal-cow manure co-gasification: The role of intrinsic AAEM and organic matter
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Hongqiao Lu, Meng Ma, Juntao Wei, Yonghui Bai, Peng Lv, Jiaofei Wang, Xudong Song, Guanghua Lu, and Guangsuo Yu
- Subjects
Co-gasification ,AAEM ,Organic ,Synergistic effect ,Reactivity ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Abstract Co-thermal chemical conversion of coal and biomass is one of the important ways to realize efficient and clean utilization of coal. In this study, a typical Ningdong coal-Yangchangwan bituminous coal and cow manure were used to study the synergistic effect of intrinsic alkali, alkaline earth metals (AAEM) and organic matter on the co-gasification of coal and biomass by thermogravimetry analyzer (TG). The results showed that AAEM had obvious synergistic promotion effect on the gasification of a bituminous coal-cow manure mixture in the isothermal gasification (1000 ℃), whereas the organic matter will show the opposite effect on the process. To further investigate the effect of organic matter on the gasification process, the influence of organic matter on non-isothermal (25-1000 ℃) gasification reaction was investigated with heating rate of 10 ℃ /min, the kinetic parameters of the gasification reaction were obtained by Coats-Redfern method. The increase of biomass mass fraction in the sample facilitates the migration of alkali metals from the material to the solid phase. The possible mechanism of the synergistic effect of intrinsic AAEM/organic matter on the co-gasification process was proposed.
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- 2024
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33. Clathrate Hydrates as a Kind of Promising Ice Nanoreactors.
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Chang, Ruisi, Cheng, Shibo, and Bu, Yuxiang
- Subjects
- *
MOLECULAR dynamics , *GAS hydrates , *CHEMICAL reactions , *ELECTRON traps , *HYDROGEN bonding - Abstract
Since their discovery, clathrate hydrates (CHs) have received great attention both from theoretical and experimental aspects due to their great potential for gas storage and prospective applications as icy crystal materials. However, there has been limited research on the decomposition, reduction or other reactions of gases enclosed in CHs. Thanks to their unique hydrogen bonding network and cavity structures, CHs can serve as the promising nanoreactors to achieve chemical conversions, e. g. reducing greenhouse gases. In this review‐type article, we characterize the potential performance of such CHs nanoreactors by discussing their multiple functions including important roles of hydrogen bonds in CHs, e. g. the confinement effect and proton source, and then discuss the enhanced electron‐binding ability of guest molecules and the structures and properties of trapped electrons in the stacked nanocages, which contribute to our understanding of chemical reactions occurring in CHs. Finally, we provide detailed analyses of representative reaction mechanisms underwent in CH nanoreactors and effective calculational and molecular dynamics simulation methods. This review‐type article aims to provide a detailed summary about the functional characteristics of CHs and reactivity in CHs, which make CHs a kind of promising icy nanoreactors. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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34. Cone Angles Quantify and Predict the Affinity and Reactivity of Anion Complexes between Trifluoroborates and Rigid Macrocycles.
- Author
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Zhang, Zhao, Sheetz, Edward G., Pink, Maren, Yamamoto, Nobuyuki, and Flood, Amar H.
- Subjects
- *
LINEAR free energy relationship , *COORDINATE covalent bond , *LEWIS acids , *ANIONS , *ANGLES - Abstract
Steric manipulation is a known concept in molecular recognition but there is currently no linear free energy relationship correlating sterics to the stability of receptor‐anion complexes nor to the reactivity of the bound anion. By analogy to Tolman cone angles in cation coordination chemistry, we explore how to define and correlate cone angles of organo‐trifluoroborates (R−BF3−) to the affinities observed for cyanostar‐anion binding. We extend the analogy to a rare investigation of the anion's reactivity and how it changes upon binding. The substituent on the anion is used to define the cone angle, θ. A series of 10 anions were studied including versions with ethynyl, ethylene, and ethyl substituents to tune steric bulk across the sp, sp2 and sp3 hybridized α‐carbons bearing 0, 1 and 2 hydrogen atoms. A linear relationship between affinity and cone angle is observed for anions bearing substituents larger than the −BF3− headgroup. This correlation predicted affinities of two new anions to within ±5 %. We explored how complexation affects the reactivity of fluoride exchange. The yield of fluoride transfer from R−BF3− to Lewis acid triphenylborane is correlated with cone angle. We predict that other rigid macrocycles, like commercially available bambusuril, could follow these trends. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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35. Carbodicarbene‐Stibenium Ion‐Mediated Functionalization of C(sp3)−H and C(sp)−H Bonds.
- Author
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Warring, Levi, Westendorff, Karl S., Bennett, Marc T., Nam, Kijeong, Stewart, Brennan M., Dickie, Diane A., Paolucci, Christopher, Gunnoe, T. Brent, and Gilliard, Robert J. Jr.
- Abstract
Main‐group element‐mediated C−H activation remains experimentally challenging and the development of clear concepts and design principles has been limited by the increased reactivity of relevant complexes, especially for the heavier elements. Herein, we report that the stibenium ion [(pyCDC)Sb][NTf2]3 (
1 ) (pyCDC=bis‐pyridyl carbodicarbene; NTf2=bis(trifluoromethanesulfonyl)imide) reacts with acetonitrile in the presence of the base 2,6‐di‐tert ‐butylpyridine to enable C(sp3)−H bond breaking to generate the stiba‐methylene nitrile complex [(pyCDC)Sb(CH2CN)][NTf2]2 (2 ). Kinetic analyses were performed to elucidate the rate dependence for all the substrates involved in the reaction. Computational studies suggest that C−H activation proceeds via a mechanism in which acetonitrile first coordinates to the Sb center through the nitrogen atom in a κ1 fashion, thereby weakening the C−H bond which can then be deprotonated by base in solution. Further, we show that1 reacts with terminal alkynes in the presence of 2,6‐di‐tert ‐butylpyridine to enable C(sp)−H bond breaking to form stiba‐alkynyl adducts of the type [(pyCDC)Sb(CCR)][NTf2]2 (3 a –f ). Compound1 shows excellent specificity for the activation of the terminal C(sp)−H bond even across alkynes with diverse functionality. The resulting stiba‐methylene nitrile and stiba‐alkynyl adducts react with elemental iodine (I2) to produce iodoacetonitrile and iodoalkynes, while regenerating an Sb trication. [ABSTRACT FROM AUTHOR]- Published
- 2024
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36. Do Confidence Ratings Reactively Modify Children's Academic Assessment Performance? Negative Answer from a Three-Year Longitudinal Study.
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Zheng, Jun, Su, Ningxin, Fan, Tian, Li, Baike, Zhao, Wenbo, Hu, Xiao, Yang, Chunliang, and Luo, Liang
- Subjects
- *
SCHOOL children , *TASK performance , *ACADEMIC achievement , *SELF-confidence , *DECISION making - Abstract
The reactivity effect of metacognitive judgments on first-order task performance has received increased research attention. Previous studies showed that soliciting retrospective confidence ratings (CRs) reactively enhances task performance itself, such as performance in decision making and reasoning tasks, especially for those with high self-confidence. It remains unknown whether CRs can improve students' academic assessment performance in real educational settings. The current study recruited 795 fourth-grade elementary school children to explore if making CRs reactively affects students' academic assessment performance in two main subjects (i.e., Chinese Language and Mathematics). The data were collected across six waves with half-year intervals. From Wave 2, children either provided (CR group) or did not provide CRs (no-CR group) when completing standardized academic assessments. The results showed Bayesian evidence supporting the claim that making CRs does not influence children's academic assessment performance (both the average performance across waves 2–6 and the performance in each wave) in both subjects. Furthermore, children's self-confidence did not moderate the reactive influence of CRs. The results from multilevel regression analyses re-confirmed the above conclusions. Possible explanations for the absence of the reactivity effect of CRs on children's academic assessment performance are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
37. Structural, electronic, and NLO properties of two acridone alkaloîds: DFT and TD-DFT studies.
- Author
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de Paul Zoua, Vincent, Atangana, Albert Fouda, Asi, Atud Quiggle, Pagoré, Ismaèl Figapka, Tatsimo, Simplice Joel Ndendoung, and Ntieche, Rahman Abdoul
- Subjects
- *
EXCITED states , *VITAMIN D , *INTEGRATED software , *OPTICAL properties , *SOLVATION - Abstract
Context: The structural, electronic, and nonlinear optical properties of Verdoocridone A (Ver A) and B (Ver B) are examined theoretically in this study. The results showed that Ver A and B exhibit good electronic properties and can be used as new materials in NLO applications. According to their maximum absorption wavelength, Ver A (λmax = 313 nm) enables production of vitamin D, while Ver B (λmax = 319.55 nm) can help skin pigmentation. Methods: All calculations were performed at the DFT/B3LYP-D3/6–311 + G(d,p) level of theory using the Gaussian 16 software package. Excited states were simulated using the TD-DFT method at the CAM-B3LYP combined with 6–311 + (d,p) basis set. Also, the solvent effect was studied in water and benzene phases by the solvation model based on density (SMD) method. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
38. Exploring the molecular solvatochromism, stability, reactivity, and non-linear optical response of resveratrol.
- Author
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Lima, Igo T., Gomes, Ramon F. C., Paura, Edson N. C., Provasi, Patricio F., Gester, Rodrigo, and Rodrigues da Cunha, Antonio
- Subjects
- *
MOLECULAR orbitals , *SECOND harmonic generation , *ELECTRONIC excitation , *DENSITY functional theory , *THERMOCHEMISTRY - Abstract
Context: This work analyzes the isomerization effects and solvent contributions to the stability, electronic excitations, reactivity, and non-linear optical properties (NLO) of resveratrol molecules within the formalism of the Density Functional Theory. The findings suggest that resveratrol solvatochromism is significantly influenced by solvent polarization. The electronic and free energies (E and G) indicate that trans is the most stable conformer. The system is classified as a strong nucleophile. However, the analysis of the Fukui functions and the Mulliken charges indicate that cis-trans isomerization jointly affects the reactive indices of the carbon and hydrogen atoms. The results also suggest that solvent is relevant to solvatochromism and the NLO response. Both cis and trans conformers present strong π - π ∗ excitations that undergo a visible hypsochromic change when the polarity of the solvent increases. Once the absorption spectra are connected to the first hyperpolarization (β ) by the Oudar and Chemla relation, the hypsochromism of resveratrol is the reason for the drop in the generation of the second harmonic when the ambient polarity decreases. The CAM-B3LYP DFT results suggest that resveratrol is interesting for NLO applications. Depending on the choice of solvent, values ∼ 50 times those observed for urea ( β = 0.34 × 10 - 34 esu), which is a standard NLO material. Methods: The optimized geometries of cis and trans isomers of resveratrol in vacuum were obtained using Density Functional Theory (DFT) with the hybrid exchange-correlation function (CAM-B3LYP) and Pople basis set functions, specifically 6-311++G(d,p). The solvent effect on the geometries of both isomers was included using the polarizable continuum model (PCM) with the same level of QM calculation. Vibrational analysis was conducted to confirm that all optimized geometries correspond to the minimum energy. Various electronic properties, including dipole moments, molecular orbitals, transition energy, dipole polarizabilities, and global reactivity parameters, were calculated using both continuum and discrete solvation models based on the sequential QM/MM methodology. All QM calculations were performed with the Gaussian 09 program and the MC simulations with the DICE program. All NLO analysis was carried out using the Multiwfn code. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. Charge transfer interaction revisited by a Fermi-Dirac derived approach.
- Author
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Gayraud, Oscar and Guégan, Frédéric
- Subjects
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CHEMICAL equations , *CHARGE transfer , *MOLECULAR orbitals , *ELECTRODE potential , *ORBITAL interaction - Abstract
Context: In this article, we adapt a recent proposition to use a Fermi-Dirac-type population scheme on Kohn-Sham molecular orbitals to the case of an interaction with a thermalised electrode. This allows to derive a fundamental non-linear equation linking the chemical potential of the electrode and the amount of charge transferred to the system under study, hence allows to quantify the propensity to charge transfer (philicity). This methodology is applied to a large set of common electrophiles and nucleophiles, showing decent relation with more standard philicity descriptors. Chemical hardness is also revisited by this approach. Methods: All calculations were performed using the Gaussian 16 software package at the M062X/aug-cc-pvtz level of theory. Data analysis was then performed through a Python3 dedicated program (relying on the fsolve numerical solver from the SciPy package), using Gaussian output files, and available as supplementary material. [ABSTRACT FROM AUTHOR]
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- 2024
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40. Examination of Acceptability, Feasibility, and Iatrogenic Effects of Ecological Momentary Assessment (EMA) of Suicidal Ideation.
- Author
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Kivelä, L. M. M., Fiß, F., van der Does, W., and Antypa, N.
- Subjects
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IATROGENIC diseases , *POST-traumatic stress disorder , *SUICIDAL ideation , *T-test (Statistics) , *DATA analysis , *STATISTICAL significance , *RESEARCH funding , *QUESTIONNAIRES , *RETROSPECTIVE studies , *ANXIETY , *CHI-squared test , *DESCRIPTIVE statistics , *BORDERLINE personality disorder , *MEDICAL records , *ACQUISITION of data , *STATISTICS , *PSYCHOLOGICAL tests , *DATA analysis software , *PATIENTS' attitudes , *MENTAL depression , *REGRESSION analysis - Abstract
Ecological momentary assessment (EMA) can be used to examine the dynamics of suicidal ideation in daily life. While the general acceptability and feasibility of EMA in suicide research has been established, further examination of potential iatrogenic effects (i.e., negative reactivity) and identifying those more likely to react negatively is needed. Participants (N = 82) with current suicidal ideation completed 21 days of EMA (4×/day) and filled in M = 78% (Med = 84%) of the EMA. No positive or negative affect reactivity was observed in EMA ratings over the study period. Retrospectively, most participants rated their experience as positive (69%); 22% indicated mood worsening, and 18% suicidal ideation reactivity. Those with more borderline personality traits, posttraumatic stress disorder (PTSD), and higher depressive, anxiety, and suicidal ideation symptoms, were more likely to report iatrogenic effects. In conclusion, while high compliance rates and lack of affect reactivity during EMA indicate that EMA is well tolerated in suicide research, a minority of participants may report subjective mood effects in retrospect. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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41. Review Essay: Limits of the Numerical and the Personalized Measurement Trend in Mental Health Care.
- Author
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de Boer, Nina S. and Runhardt, Rosa W.
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MENTAL health services , *PSYCHOMETRICS , *SAMPLING methods - Abstract
Limits of the Numerical calls for the (re)contextualization of the numerical in the social domain and emphasizes that using quantitative data has epistemic and practical/moral considerations that may not align. In this review essay, we evaluate these claims using a case study, viz. the personalized, clinical experience sampling method (ESM) in mental health care. This case study (1) nuances claims made in Limits of the Numerical regarding the generality and non-contextuality of numerical data, and (2) highlights two additional dimensions to the numerical that have been underexposed in the book (i.e., reactivity and Ballung concepts). [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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42. Hindrances and solutions on the path towards adjoined barium titanate–hydroxyapatite ceramics with uncompromised piezoelectric and biological responses.
- Author
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Cioangher, M., Amarande, L., Stan, G.E., Nedelcu, L., Pasuk, I., Leonat, L., Popa, A.C., Miclea, L.C., Savopol, T., Moisescu, M.G., and Tivig, I.
- Subjects
- *
PIEZOELECTRIC ceramics , *BONE substitutes , *BARIUM , *BIODEGRADATION , *BARIUM titanate , *LEAD zirconate titanate , *HYDROXYAPATITE , *POWDERS - Abstract
The synergistic piezoelectric and osteoconductive properties of barium titanate (BT) and hydroxyapatite (HA) could stir the development of a new generation of synthetic bone graft substitutes, with capability for rapid and safe osseointegration. The research focused on two concurrent approaches for coupling the BT and HA materials: (i) conventional sintering of BT-HA powder mixtures; and (ii) functionalization of pre-sintered BT with HA coatings using magnetron sputtering (MS). Irrespective of the BT/HA ratios ranging from 95/5 to 80/20 wt%, nanocrystalline or highly-crystallized nature of the powders, sub-micron- or micron-sized particle dimensions, and sintering temperature, it was observed that the BT-HA reactivity cannot be prevented above 800 °C. At higher temperatures in the range of 1000–1300 °C, HA undergoes decomposition and extensively reacts with BT, leading to the formation of several secondary phases such as CaTiO 3, Ba 2 Ca(PO 4) 2 , BaCa 6 (PO 4) 4 O, BaCa(PO 3) 4 , and β -Ca 2 P 2 O 7. As a consequence, the cytocompatibility assessed in fibroblast and osteoblast cell cultures, as well as the piezoelectric response, were significantly altered. Applying HA coatings by MS to the sintered BT ceramics successfully preserved their piezoelectric properties, while also providing an unaltered cytocompatible and osteogenic-prone surface. The HA coatings were fully crystallized at post-deposition annealing temperatures of 550 and 700 °C, achieving crystalline qualities comparable to HA powders sintered at 1100 and 1200 °C, respectively. No reactivity events between BT and HA were observed. Partial reactivity was only noticeable upon annealing at 1000 °C. Therefore, it is suggested that the HA coating of BT is effective in seamlessly coupling the piezoelectric and osteogenic properties of the two constituents without compromise. • BT-HA powder mixtures inevitably react at high-temperature to form secondary phases. • The HA osteogenic component can be lost at sintering temperatures above 1000 °C. • The secondary phases lead to a decay of the piezoelectric and biological responses. • HA-magnetron sputtered BT – a feasible solution to overcome inter-phases reactivity. • HA-coated BT yields uncompromised piezoelectric and in-vitro biologic performances. [ABSTRACT FROM AUTHOR]
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- 2024
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43. Accounting, Calculative Infrastructures and Commensuration Work.
- Author
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Svärdsten, Fredrik and Modell, Sven
- Abstract
Accounting scholars are paying increasing attention to the notion of commensuration, or the translation of different objects into common metrics that make the entities that are subject to performance evaluation comparable, and the effects this has on organizational behavior. This body of research draws attention to organizations' commensuration work, defined as the efforts that evaluated organizations expend in pursuing and dealing with resistance to commensuration, but has mainly explored how such work emerges in response to a single set of comparable metrics such as individual rankings or ratings. By contrast, we ask how commensuration work unfolds in relation to a broader assemblage of calculative infrastructures. Such infrastructures can entail multiple, inter-related performance evaluation procedures that influence organizations' commensuration work and give rise to complex patterns of reactivity, denoting the propensity of organizations to alter their behavior as they internalize external pressures for performance evaluation. Our empirical findings underline the importance of adopting a multi-layered view of commensuration work, that entails both direct and indirect forms of reactivity, as it unfolds in relation to a broader assemblage of calculative infrastructures. We discuss the implications of adopting such a view for future research on commensuration and related research on performance evaluation. [ABSTRACT FROM AUTHOR]
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- 2024
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44. Mechano-chemical, high-consistency activation of kraft pulp in deep eutectic solvent of choline chloride and urea.
- Author
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Vehviläinen, Marianna, Suopajärvi, Terhi, Sirviö, Juho Antti, Spönla, Elisa, Ahokas, Pauliina, Rahikainen, Jenni, Minkkinen, Hannu, and Liimatainen, Henrikki
- Subjects
INTRINSIC viscosity ,SULFATE pulping process ,CHOLINE chloride ,FIBERS ,CELLULOSE ,XYLANS - Abstract
Deep eutectic solvents (DESs) offer an appealing green medium for the activation of cellulose fibres to promote their swelling, reactivity, hydrolysis, disintegration, and solubility for further processing. Typically, DES treatments are carried out below 5 wt% consistency even though a higher solids content could enhance the fibre activation and reduce the solvent consumption. In this work, a high-consistency (HC) mechano-chemical activation of bleached softwood kraft pulp was elucidated using a simultaneous fibre treatment with DES of choline chloride-urea and a sigma-type kneader or a twin-screw extruder at a solids content of 15–35 wt% and 30 wt%, respectively. Both HC treatments efficiently triggered fibre swelling, which was indicated by an increase in the fibre width, and loosened the cell wall structure which was indicated by an increase in the mesopore volume. Mechano-chemical HC processing generated fibre fines and external fibrillation, while the molecular-level structural alteration or changes in chemical composition were minor; the intrinsic viscosity and the crystallinity of the pulp remained at their initial level and only a small amount of xylan was dissolved. Overall, HC treatment in a twin-screw extruder caused notably more severe morphological changes in the fibres than batch treatment in a sigma-type kneader. Thus, the mechano-chemical HC treatment with DES provides an industrially relevant technology for cellulose modification and opens possibilities to enhance heterogeneous cellulose modification processes in which the highly available surface area of pulp is a key parameter. [ABSTRACT FROM AUTHOR]
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- 2024
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45. Optimizing Construction Spoil Reactivity for Cementitious Applications: Effects of Thermal Treatment and Alkaline Activation.
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Wang, Kai and Zha, Xiaoxiong
- Subjects
CONSTRUCTION & demolition debris ,DEBRIS avalanches ,NATURAL disasters ,CONSTRUCTION materials ,PRODUCTION quantity ,LANDSLIDES - Abstract
Construction spoil (CS), a prevalent type of construction and demolition waste, is characterized by high production volumes and substantial stockpiles. It contaminates water, soil, and air, and it can also trigger natural disasters such as landslides and debris flows. With the advent of alkali activation technology, utilizing CS as a precursor for alkali-activated materials (AAMs) or supplementary cementitious materials (SCMs) presents a novel approach for managing this waste. Currently, the low reactivity of CS remains a significant constraint to its high-value-added resource utilization in the field of construction materials. Researchers have attempted various methods to enhance its reactivity, including grinding, calcination, and the addition of fluxing agents. However, there is no consensus on the optimal calcination temperature and alkali concentration, which significantly limits the large-scale application of CS. This study investigates the effects of the calcination temperature and alkali concentration on the mechanical properties of CS–cement mortar specimens and the ion dissolution performance of CS in alkali solutions. Mortar strength tests and ICP ion dissolution tests are conducted to quantitatively assess the reactivity of CS. The results indicate that, compared to uncalcined CS, the ion dissolution performance of calcined CS is significantly enhanced. The dissolution amounts of active aluminum, silicon, and calcium are increased by up to 420.06%, 195.81%, and 256.00%, respectively. The optimal calcination temperature for CS is determined to be 750 °C, and the most suitable alkali concentration is found to be 6 M. Furthermore, since the Al O bond is weaker and more easily broken than the Si O bond, the dissolution amount and release rate of active aluminum components in calcined CS are substantially higher than those of active silicon components. This finding indicates significant limitations in using CS solely as a precursor, emphasizing that an adequate supply of silicon and calcium sources is essential when preparing CS-dominated AAMs. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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46. Synergistic Effects in Co-Gasification of Willow and Cedar Blended Char in CO 2 Media.
- Author
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Koido, Kenji, Endo, Kenji, Morimoto, Hidetsugu, Ohashi, Hironori, and Sato, Michio
- Subjects
- *
CRYPTOMERIA japonica , *FARMS , *CHAR , *WILLOWS , *CARBON dioxide , *BIOMASS gasification - Abstract
Willow is a promising biomass resource for addressing the challenges of securing stable domestic biomass fuels in Japan and utilising abandoned agricultural land. Among the willow species, Salix pet-susu Kimura KKD (known as ezonokinu willow, EW) stands out for its growth, high production, storage stability, production stability, and business stability. Previous studies have investigated fuel characterisation through gasification (co-gasification) of various biomass mixtures to enhance feedstock flexibility for gasifier commercialisation. However, the synergistic effects of co-gasification using fuels containing EW blended with Japanese cedar, a commonly planted forest species in Japan, remain unexplored. Therefore, this study explored CO2 co-gasification with different blend ratios of EW/cedar blended char and evaluated the fuel characteristics for each blend ratio to elucidate the synergistic effects. The prepared char samples were utilised in the CO2 gasification test with TG-DTA as the analyser. The results suggest that in the initial stages of the willow/cedar blended char co-gasification reaction, pore size and specific surface area significantly influence the reaction rate. Subsequent stages of the reaction are influenced by the promoting and inhibiting effects of inorganic components, which impact co-gasification. The synergy factor results for the willow/cedar blended char co-gasification suggest a reaction pathway. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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47. Divalent Titanium via Reductive N−C Coupling of a TiIV Nitrido with π‐Acids.
- Author
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Bhunia, Mrinal, Sandoval‐Pauker, Christian, Fehn, Dominik, Grant, Lauren N., Senthil, Shuruthi, Gau, Michael R., Ozarowski, Andrew, Krzystek, J., Telser, Joshua, Pinter, Balazs, Meyer, Karsten, and Mindiola, Daniel J.
- Abstract
The nitrido‐ate complex [(PN)2Ti(N){μ2‐K(OEt2)}]2 (1) (PN−=(N‐(2‐PiPr2‐4‐methylphenyl)‐2,4,6‐Me3C6H2) reductively couples CO and isocyanides in the presence of DME or cryptand (Kryptofix222), to form rare, five‐coordinate TiII complexes having a linear cumulene motif, [K(L)][(PN)2Ti(NCE)] (E=O, L=Kryptofix222, (2); E=NAd, L=3 DME, (3); E=NtBu, L=3 DME, (4); E=NAd, L=Kryptofix222, (5)). Oxidation of 2–5 with [Fc][OTf] afforded an isostructural TiIII center containing a neutral cumulene, [(PN)2Ti(NCE)] (E=O, (6); E=NAd (7), NtBu (8)) and characterization by CW X‐band EPR spectroscopy, revealed unpaired electron to be metal centric. Moreover, 1e− reduction of 6 and 7 in the presence of Kryptofix222cleanly reformed corresponding discrete TiII complexes 2 and 5, which were further characterized by solution magnetization measurements and high‐frequency and ‐field EPR (HFEPR) spectroscopy. Furthermore, oxidation of 7 with [Fc*][B(C6F5)4] resulted in a ligand disproportionated TiIV complex having transoid carbodiimides, [(PN)2Ti(NCNAd)2] (9). Comparison of spectroscopic, structural, and computational data for the divalent, trivalent, and tetravalent systems, including their 15N enriched isotopomers demonstrate these cumulenes to decrease in order of backbonding as TiII→TiIII→TiIV and increasing order of π‐donation as TiII→TiIII→TiIV, thus displaying more covalency in TiIII species. Lastly, we show a synthetic cycle whereby complex 1 can deliver an N‐atom to CO and CNAd. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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48. Understanding Gold‐Alkyne Activation from Bond Dissociation Energies of Gold‐Alkyne Complexes.
- Author
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Gatineau, David, Lesage, Denis, Guéret, Rodolphe, Mador, Samuel Danladi, Milet, Anne, and Gimbert, Yves
- Subjects
- *
TANDEM mass spectrometry , *ION-molecule collisions , *POLAR effects (Chemistry) , *MASS spectrometers , *EXCHANGE reactions , *COLLISION induced dissociation - Abstract
A detailed approach into electronic effects of ligands on gold‐alkyne interactions has been carried out in the gas phase using tandem mass spectrometry. A semi‐empirical method coupled to DFT calculations was used to quantify ligands effects on Au−CC bond strength. To this end, the critical energies of 16 [L−Au‐hex‐3‐yne]+ complexes with different L ligands were determined through collision induced dissociation. It was observed that electron‐rich ligands destabilize the gold‐alkyne bond, whereas phosphites and carbenes strengthened it. The influence of alkyne electronic effects on the gold‐alkyne bond has also been studied by dissociation in tandem mass spectrometry on four different alkynes. In an original approach, two successive ion‐molecule reactions within the mass spectrometer were used to measure the relative affinity of gold to an alkyne by exchange reactions. The result is that the more electron‐rich the alkyne, the stronger the gold‐alkyne bond. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
49. In-silico design of novel 2-((4-chloro-6-methoxy-1H-indol-3-yl) thio)-N-(2-ethoxyphenyl)acetamide derivatives as potential inhibitors of influenza neuraminidase protein receptor.
- Author
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Abdullahi, Mustapha, Uzairu, Adamu, Shallangwa, Gideon Adamu, Mamza, Paul Andrew, Ibrahim, Muhammad Tukur, Chandra, Anshuman, and Singh, Nagendra
- Subjects
- *
ACETAMIDE , *INFLUENZA , *NEURAMINIDASE , *PROTEIN receptors , *DRUG resistance - Abstract
Influenza virus transmission is largely mediated by its mutation and genome reassortment from distinct strains resulting in drug-resistances and pandemics. This necessitates the need for the discovery of more potential influenza inhibitors to prevent future epidemics. An in-silico approach was utilized here to design six new (21a-f) potential inhibitors of influenza neuraminidase (NA) using a hit compound 21 with good binding affinity, pre- dicted activity, and pharmacokinetic properties in our previous work. The modeled activities (pEC50) of the newly designed compounds (ranging between 8.188 and 7.600) were better than that of the hit compound 21 with predicted activity (pEC50) of 6.0101 and zanamivir (pEC50 of 5.6755) as the standard reference control used. The MolDock scores (ranging between-189.67 and 142.47 kcal/mol) of these newly designed compounds in the NA binding cavity were also better than the hit template 21 with a MolDock score of-125.33 kcal/mol and zanamivir standard drug (-136.36 kcal/mol). In addition, the conformational stability of the best-designed compound 21a in the NA binding cavity was further studied through the MD simulation of 100 ns. Moreover, the drug-likeness and ADMET predictions of these designed compounds showed their good oral bioavailability and pharmacokinetic profiling respectively. More so, the DFT calculations also revealed the relevance of these designed com- pounds in view of their smaller band energy gaps from the frontier molecular orbital calculations. This study could serve as a reliable in-silico perspective for the search and discovery of potential anti-influenza agents. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
50. Towards Construction of the "Periodic Table" of 1-Methylbenzotriazole.
- Author
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Stamou, Christina, Lada, Zoi G., Paschalidou, Sophia, Chasapis, Christos T., and Perlepes, Spyros P.
- Subjects
- *
COPPER , *INORGANIC chemistry , *COORDINATE covalent bond , *COPPER-zinc alloys , *METAL complexes , *FUNCTIONAL groups , *LIGANDS (Chemistry) - Abstract
Metal complexes of benzotriazole-type ligands continue to attract the intense interest of many inorganic chemistry groups around the world for a variety of reasons, including their aesthetically beautiful structures, physical properties and applications. 1-methylbenzotriazole (Mebta) is the N-substituted archetype of the parent 1H-benzotriazole. The first attempt to build a "periodic table" of Mebta, which includes its complexes with several metal ions, is described in this work. This, at first glance, trivial ligand has led to interesting results in terms of the chemistry, structures and properties of its metal complexes. This work reviews the to-date published coordination chemistry of Mebta with Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(I), Cu(II), Zn(II), Pd(II), Au(I) and {UVIO2}2+, with emphasis on their preparations, reactivity, structures and properties. Unpublished results from our group comprising other Co(II), Ni(II), Cu(II) and Zn(II) complexes, as well as Cd(II), Hg(II), Ag(I), In(III) and Sn(IV) ones are briefly reported. Mebta can also provide access to 1D and 3D heterometallic thiocyanato-bridged Co(II)/Hg(II) and Ni(II)/Hg(II) compounds. In almost all cases, Mebta behaves as a monodentate ligand with the nitrogen of position 3 of the azole ring as the donor atom. However, there are two copper complexes in which this molecule adopts a bidentate bridging coordination behavior. Our efforts to complete the "periodic table" of Mebta are continued. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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