Search

Bi2O3 was proven an attractive compound for electrode modification in heavy metal electrochemical analysis. A novel method for synthesizing Bi2O3-attached multiwalled carbon nanotubes (Bi2O3@CNTs) in solution is successfully developed in this study. Characteristics of the obtained Bi2O3@CNTs were proven by modern techniques such as X-ray diffraction, Raman spectroscopy, scanning electronic microscopy, transmission electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and anodic stripping voltammetry. Microscopy images and spectra results reveal that Bi2O3 particles are mainly attached at defect points on multiwalled carbon nanotubes (MWCNTs) walls. Paste electrodes based on the MWCNTs and synthesized Bi2O3@CNTs were applied for electrochemical measurements. The redox mechanism of Bi2O3 on the electrode surface was also made clear by the cyclic voltammetric tests. The recorded cyclic voltammograms and electrochemical impedance spectroscopy demonstrate that the Bi2O3@CNTs electrode was in lower charge transfer resistance than the CNTs one and in the controlled diffusion region. Investigation on the electrochemical behavior of Pb2+ at the Bi2O3@CNTs electrodes found a significant improvement of analytical response, resulting in 3.44 μg/L of the detection limit and 2.842 μA/(μg/L) of the sensitivity with linear sweep anodic stripping voltammetry technique at optimized conditions.

In recent years, water pollution has developed into a severe environmental and public health problem due to rapid urbanization and industrialization, especially in some developing countries. Finding solutions to tackle water pollution is urgently required and is of global importance. Currently, a range of water treatment methods are available; however, a water remediation process that is simple, inexpensive, eco-friendly, and effective for the removal of pollutants down to ppm/ppb concentrations has long been sought after. Herein, we describe a novel approach using fungal melanin for developing melanized-cationic cellulose nanofiber (melanized-C-CNF) foams that can successfully remove pollutants in water systems. The foam can be recycled several times while retaining its adsorption/desorption property, indicating high practicability for adsorbing the cationic dye crystal violet. This work highlights the opportunity to combine both the advanced features of sustainable polymers such as cellulose and the unique properties of fungal melanin to manufacture biohybrid composites for water purification.

Background Phenotypic characteristics of patients with eosinophilic and noneosinophilic asthma are not well characterized in global, real-life severe asthma cohorts. Research Question What is the prevalence of eosinophilic and noneosinophilic phenotypes in the population with severe asthma, and can these phenotypes be differentiated by clinical and biomarker variables? Study Design and Methods This was an historical registry study. Adult patients with severe asthma and available blood eosinophil count (BEC) from 11 countries enrolled in the International Severe Asthma Registry (January 1, 2015-September 30, 2019) were categorized according to likelihood of eosinophilic phenotype using a predefined gradient eosinophilic algorithm based on highest BEC, long-term oral corticosteroid use, elevated fractional exhaled nitric oxide, nasal polyps, and adult-onset asthma. Demographic and clinical characteristics were defined at baseline (ie, 1 year before or closest to date of BEC). Results One thousand seven hundred sixteen patients with prospective data were included; 83.8% were identified as most likely (grade 3), 8.3% were identified as likely (grade 2), and 6.3% identified as least likely (grade 1) to have an eosinophilic phenotype, and 1.6% of patients showed a noneosinophilic phenotype (grade 0). Eosinophilic phenotype patients (ie, grades 2 or 3) showed later asthma onset (29.1 years vs 6.7 years; P Interpretation According to this multicomponent, consensus-driven, and evidence-based eosinophil gradient algorithm (using variables readily accessible in real life), the severe asthma eosinophilic phenotype was more prevalent than previously identified and was phenotypically distinct. This pragmatic gradient algorithm uses variables readily accessible in primary and specialist care, addressing inherent issues of phenotype heterogeneity and phenotype instability. Identification of treatable traits across phenotypes should improve therapeutic precision.

We report the kinetics of ethylene oligomerization over the Ni-H-Beta for temperatures ranging between 50 and 100 °C and pressures ranging between 5 and 28 atm. According to our results, the apparent activation energies involved in the formation of butene, hexene, and octene are 44, 78, and 60 kJ.mol−1, respectively. The measured lower apparent activation energy for butene formation relative to hexene and octene is a likely result of the fact that the measured butene formation is not the true (forward) rate of formation of butene but it the net rate because of the consumption of butene in secondary reactions. Analysis of the reaction order indicates that participation of butene in chain-growth reactions takes place via desorption followed by re-adsorption of butene on the catalyst. The results also indicate that hexene undergoes a similar process. In the present paper, we refer to the pathway involving co-oligomerization of butene and hexene as “cascade co-oligomerization”. Based on these findings, we proposed a reaction network and modeled reaction rate expressions for ethylene consumption and butene, hexene, and octene formation based on the construction of a micro-kinetic model. We calculated the kinetic parameters involved in the reaction network proposed and found evidence that the formation of octene proceeds mainly via the “cascade co-oligomerization” of re-adsorbed butene with ethylene.

Substituted pyrans and furans are core structures found in a wide variety of natural products and biologically active compounds. Herein, we report a practical and mild catalytic method for the synthesis of substituted pyrans and furans using molecular iodine, a simple and inexpensive catalyst. The method described is performed under solvent-free conditions at an ambient temperature and atmosphere, thus offering a facile and practical alternative to currently available reaction protocols. A combination of experimental studies and density functional theory calculations revealed interesting mechanistic insights into this seemingly simple reaction.

A series of (N2P2)NiII complexes (N2P2 = P,P′-ditertbutyl-2,11-diphosphonito[3.3](2,6)pyridinophane) stabilized by a modified tetradentate pyridinophane ligand containing two phosphonite groups wer...

Two new flavonoids, named bougainvinones N–O (1–2), together with the five known compounds (3–7), were isolated from the roots of Bougainvillea spectabilis. The chemical structures were elucidated by spectroscopic analyses, including 1D and 2D NMR and HR-ESI-MS. All compounds were evaluated for cytotoxic effects against four cancer cell lines, including HeLa, NCI-H460, MCF-7 and HepG2. Among them, bougainvinone O (2) showed moderate activity against the MCF-7 cell line, with an IC50 value of 43.64 μM.

Two isostructural lanthanide metal–organic frameworks (Ln-MOF-589, Ln = La3+, Ce3+), constructed from a tetratopic linker, benzoimidephenanthroline tetracarboxylic acid (H4BIPA-TC), have been solvothermally synthesized and characterized. These Ln-MOF-589 materials consist of Lewis acid [Ln2(-COO)6(-COOH)2(H2O)6] units and a naphthalene diimide core, which exhibited promising catalytic activity for the oxidation of olefins. Among them, Ce-MOF-589 exhibited outstanding performance with high conversions of styrene and cyclohexene (94 and 90%, respectively), and good selectivities towards styrene oxide and 2-cyclohexen-1-one (85, and 95%, respectively). Notably, the catalytic activity of Ce-MOF-589 outperformed that of homogeneous and heterogeneous catalysts, and representative MOFs. Also, Ce-MOF-589 can be recycled for at least up to six cycles with no significant loss of catalytic performance.

In the course of bioassay-guided study for natural antidiabetic compounds from microorganisms, two steroids, i.e. compounds 1 and 2, were isolated in vitro from biomass of antidiabetic Streptomyces sp. strain TD-X10. Structures of the compounds 1 and 2 were elucidated on the basis of spectroscopic analysis of nuclear magnetic resonance and mass spectral data and comparison with reported literature data as β-sitosterol and β-sitosteryl ferulate, respectively. While compound 1 exhibited faintly inhibitory activity against protein tyrosine phosphatase 1B, a highly validated therapeutic target for diabetes mellitus, compound 2 displayed a moderate inhibitory effect to the enzyme with IC50 value of 40.05 ± 2.46 µM. The results highlight the antidiabetic potential of natural products from actinobacteria, particularly Streptomyces species.

Bismuth-based halide perovskites are non-toxic alternatives to widely researched lead-containing halide perovskites for optoelectronics. Cesium bismuth bromide, in particular, may have good optical properties, but photoluminescence data reported to date are confusing and contradictory. Here we resolve the literature discrepancies and show that Cs3Bi2Br9 thin films deposited by physical vapor deposition show absorption and emission peaks at 433 and 472 nm, respectively. Peak location and lineshapes of blue-shifted (390–440 nm) photoluminescence previously reported and attributed to quantum confinement in Cs3Bi2Br9 nanocrystal dispersions could be reproduced in BiBr3 solutions in different solvents but without Cs3Bi2Br9 nanocrystals present. This suggests that high quantum yield photoluminescence reported in this wavelength range may be originating from unreacted precursors and impurities in nanocrystal dispersions rather than from Cs3Bi2Br9 quantum dots. The addition of Yb that can substitute up to 50% of the Bi in Cs3Bi2Br9 leaves the Cs3Bi2Br9 structure unchanged and results in near-infrared Yb3+ 2F5/2 → 2F7/2 emission (1.25 eV) with 14.5% quantum yield. This emission decreases sharply when the perovskite host's bandgap is reduced below 2.5 eV, twice the Yb3+ emission energy, by substituting bromine with iodine, raising the possibility that the emission mechanism involves quantum cutting. This would make lead-free Cs3Bi2Br9 a potential quantum cutting material for solar spectrum shaping to increase solar cell efficiency.

This study was conducted to evaluate feeding periods of dietary conjugated linoleic acid (CLA) supplementation on growth performance, nutrient digestibility, blood profiles, and meat quality in finishing pigs. A total of 150 finishing pigs [(Yorkshire × Landrace) × Duroc] with an average body weight (BW) of 83.13 ± 1.91 kg were randomly allocated into one of three treatments (10 pens per treatment, five pigs per pen) based on their BW. Dietary treatments consisted of supplementing the basal diet with 1.0% CLA during 2, 3, and 4 wk prior to finishing. Pigs fed CLA diets 2 wk before finishing had a higher overall average daily gain (ADG) and gain-to-feed ratio (G/F) than those fed CLA diets 4 wk before finishing (P

Graphitic (sp2-rich) carbon Schottky contacts to ( $\overline {2}01$ ) $\beta $ -Ga2O3 were fabricated using sputtering and energetic ion deposition with and without the use of an oxygen plasma. As-deposited contacts exhibited room temperature effective barrier heights between 0.80 and 1.20 eV, depending on the deposition technique. After moderate heat treatment (595 K in N2) the work function of the oxygenated graphitic contacts increased by 0.5–0.8 eV. This resulted in a permanent increase in barrier height (up to 1.6 eV) and a corresponding 3–4 orders of magnitude increase in current rectification (at ±3 V). The barrier heights of the heat-treated oxygenated graphitic Schottky contacts agree well with the Mott–Schottky model, suggesting an absence of Fermi level pinning at the C/ $\beta $ -Ga2O3 interface.

Aryl boronic acids and esters are important building blocks in API synthesis. The palladium-catalyzed Suzuki-Miyaura borylation is the most common method for their preparation. This paper describes an improvement of the current reaction conditions. By using lipophilic bases such as potassium 2-ethyl hexanoate, the borylation reaction could be achieved at 35 °C in less than 2 h with very low palladium loading (0.5 mol %). A preliminary mechanistic study shows a hitherto unrecognized inhibitory effect by the carboxylate anion on the catalytic cycle, whereas 2-ethyl hexanoate minimizes this inhibitory effect. This improved methodology enables borylation of a wide range of substrates under mild conditions.

Cobalt doping at the iron site of barium hexaferrites (BaFe12−xCoxO19, x = 0 − 2.0, Δx = 0.5) was done using a co-precipitation method followed by a heat treatment at 900 °C. Careful refinement of the X-ray diffraction patterns by using the Rietveld method revealed a transformation from a hexagonal to a mixed hexagonal and cubic spinel structure. The undoped sample was ∼95% barium M-type hexaferrites (BaFe12O19), with the other 5% being made up barium Y-type hexaferrites (Ba2Fe14O22: 3.50%) and spinel ferrites (Fe3O4: 1.62%). The replacement of Fe3+ by Co2+ led to a charge imbalance which promoted the growth of Y-type hexaferrites (Ba2CoxFe 14−xO22) and spinel ferrites (CoxFe3−xO4). The impurity phases grew linearly from 5.12% for x = 0 to 67.21% for x = 2.0, leading to a linear decrease in barium M-type hexaferrites (94.88% for x = 0 to 32.79% for x = 2.0). A structural study by using Raman scattering spectroscopy confirmed the growth of Y-type hexaferrites and spinel ferrites by detecting new modes at 319, 325, 519, 569, 640 and 675 cm−1. As to the electromagnetic properties, three of the four parameters were changed by doping in the frequency range from 2 to 18 GHz for samples with thickness of t = 1.50 mm. Both the real (μ′) and the imaginary (μ″) parts of the complex permeability and the real part (e′) of the complex permittivity increased with increasing doping. This tuned the reflection loss (RL) from poor (RL = −5.0 dB at f = 12.5–13.0 GHz) for the undoped sample to fairly good for doped samples (RL = − 10.5 dB and −16.0 dB for x = 2.0 and 1.0, respectively, at f = 17.0 GHz). A study of the thickness (t) dependence of the RL in the range t = 2.75–1.50 mm pointed out that our samples also had some features similar to those of metamaterials, especially for thick samples at a frequency closeto18 GHz for the x = 0 sample.

An empirical scale-up model of the pan-coating process for controlled-release urea fertilizer (CRUF) was novel performed via a pan-coating process using the biodegradable polymer solution. The simi...

In light of the chemical exploitation of CO2, new reusable materials for efficiently catalyzing the cycloaddition of CO2 and epoxides under moderate conditions are needed. Herein, a new series of i...

Palladium is a versatile transition metal used to catalyze a large number of chemical transformations, largely due to its ability to access various oxidation states (0, I, II, III, and IV). Among these oxidation states, Pd(I) is arguably the least studied, and while dinuclear Pd(I) complexes are more common, mononuclear Pd(I) species are very rare. Reported herein are spectroscopic studies of a series of Pd(I) intermediates generated by the chemical reduction at low temperatures of Pd(II) precursors supported by the tetradentate ligands 2,11-dithia[3.3](2,6)pyridinophane (N2S2) and

Islet transplantation in man is limited by multiple factors including islet availability, islet cell damage caused by collagenase during isolation, maintenance of islet function between isolation and transplantation, and allograft rejection. In this study, we describe a new approach for preparing islets that enhances islet function in vitro and reduces immunogenicity. The approach involves culture on native decellularized 3D bone marrow-derived extracellular matrix (3D-ECM), which contains many of the matrix components present in pancreas, prior to islet transplantation. Compared to islets cultured on tissue culture plastic (TCP), islets cultured on 3D-ECM exhibited greater attachment, higher survival rate, increased insulin content, and enhanced glucose-stimulated insulin secretion. In addition, culture of islets on 3D-ECM promoted recovery of vascular endothelial cells within the islets and restored basement membrane-related proteins (eg, fibronectin and collagen type VI). More interestingly, culture on 3D-ECM also selectively decontaminated islets of "passenger" cells (co-isolated with the islets) and restored basement membrane-associated type VI collagen, which were associated with an attenuation in islet immunogenicity. These results demonstrate that this novel approach has promise for overcoming two major issues in human islet transplantation: (a) poor yield of islets from donated pancreas tissue and (b) the need for life-long immunosuppression.

Male and female Plasmodium falciparum gametocytes are the parasite lifecycle stage responsible for transmission of malaria from the human host to mosquito vector. Not only are gametocytes able to survive in radically different host environments, but they are also precursors for male and female gametes that reproduce sexually soon after ingestion by the mosquito. Here we investigate the sex-specific lipid metabolism of gametocytes within their host red blood cell and poised for ingestion by the mosquito vector and subsequent sexual reproduction.Comparison of the male and female lipidome identifies cholesteryl esters and dihydrosphingomyelin enrichment in female gametocytes. Chemical inhibition of each of these lipid types in mature gametocytes suggests dihydrosphingomyelin synthesis but not cholesteryl ester synthesis is important for sex-specific gametocyte viability. Genetic disruption of each of the two sphingomyelin synthase gene points towards sphingomyelin synthesis contributing to gametocytogenesis.This study shows that gametocytes are not only distinct from asexual stages, but that the lipid composition is also vastly different between male and female gametocytes, reflecting the different cellular roles these stages play. Together our results highlight the sex-specific nature of gametocyte lipid metabolism that has the potential to be targeted to block malaria transmission.

The electrochemical hydrogen evolution reaction (HER) is considered a sustainable energy approach to advance fuel-cell technologies, and HER electrocatalysts that resembles the [NiFe] hydrogenases are highly desired. Herein, we report a bioinspired Ni(II) complex (NCHS2)Ni(OTf)2, where NCHS2 is 3,7-dithia-1(2,6)-pyridina-5(1,3)-benzenacyclooctaphane, that is an efficient electrocatalyst for HER with turnover frequencies up to 400,000 s–1 in the presence of low acid concentration, and compares favorably with the other reported Ni HER electrocatalysts. Importantly, in this complex the rationally designed NCHS2 ligand undergoes C-H bond activation and the resulting organometallic Ni-aryl complex restricts the formation of a Ni(0) species, which resembles the role of the cysteine ligands in [NiFe] hydrogenases. In addition, this electrocatalyst follows a unique HER mechanism via detectable Ni(I)/Ni(III) intermediates that are also proposed for [NiFe] hydrogenases, yet such a mechanism has not been observed to date in model systems.

In the search for lead-free perovskites for solar cells, cesium bismuth halides are emerging as potential optoelectronic materials. Cs+, Bi3+ and Br− can form multiple compounds with different stoichiometries and crystal structures. Among these, Cs3Bi2Br9 and Cs3BiBr6 are stable in air at room temperature. Published optical absorption data for Cs3Bi2Br9 vary significantly from article to article, while there are limited data on the newly discovered Cs3BiBr6. Herein we resolve the discrepancies in the literature and fill in the knowledge gaps by depositing phase pure Cs3Bi2Br9 and Cs3BiBr6 thin films via co-evaporation of CsBr and BiBr3 in high vacuum and studying the effects of CsBr:BiBr3 ratio on the optical properties of well-characterized films. Cs3Bi2Br9 and Cs3BiBr6 thin films show absorption peaks centered at 435 nm and 383 nm, respectively. These peaks are associated with excitations localized on [BiBr6]3− octahedra in the solid phase but the latter also coincides with absorption by [BiBr6]3− in liquid solutions. We show that the discrepancies in the literature on optical absorption of Cs3Bi2Br9 can have two explanations: Cs3BiBr6 phase impurities or the inevitable absorption by dissolved [BiBr6]3− in colloidal dispersions, which may be easily misinterpreted as originating from the solid product.

Nickel/photoredox catalyzed C–N couplings of hydrazine-derived nucleophiles provide a powerful alternative to Pd-catalyzed methods. This continuous-flow photochemical protocol, optimized using design of experiments, achieves these couplings in short residence times, with high selectivity. A range of (hetero)aryl bromides and chlorides are compatible and understanding of process stability/reactor fouling has been discerned.

Tropylium bromide undergoes noncatalyzed, regioselective additions to a large variety of Michael acceptors. In this way, acrylic esters are converted into β-bromo-α-cycloheptatrienylpropionic esters. The reactions are interpreted as nucleophilic attack of bromide ions at the electron-deficient olefins and the approach of the tropylium ion to the incipient carbanion. Quantum chemical calculations were performed to elucidate the analogy to the amine- or phosphine-catalyzed Rauhut-Currier reactions. Subsequent synthetic transformations of the bromo-cycloheptatrienylated adducts are reported.

Netropsin is one of the first ligands to be discovered that selectively binds to the minor groove of DNA and is actively used as a scaffold for developing potential anticancer and antibiotic agents. The mechanism by which netropsin binds to hairpin DNA remains controversial with two competing mechanisms having been proposed. In one mechanism, netropsin binding induces a hairpin-to-duplex DNA transition. Alternatively, netropsin binds in two thermodynamically different modes at a single duplexed AATT site. Here, results from native mass spectrometry (MS) with nanoscale ion emitters indicate that netropsin can simultaneously and sequentially bind to both hairpin and duplex DNA. Duplex DNA was not detected using conventional MS with larger emitters because nanoscale emitters significantly reduce the extent of salt adduction to ligand-DNA complex ions, including in the presence of relatively high concentrations of nonvolatile salts. Based on native MS and polyacrylamide gel electrophoresis results, the abundances of hairpin and duplex DNA are unaffected by the addition of netropsin. By native MS, the binding affinities for five ligand-DNA and DNA-DNA interactions can be rapidly obtained simultaneously. This research indicates a "simultaneous binding mechanism" for the interactions of netropsin with DNA.

A total of 105 finishing pigs [(Yorkshire × Landrace) × Duroc] with an initial body weight of 51.0 ± 3.33 kg were used in a 10 wk trial to evaluate the effect of a protected blend of organic acids ...

Three-finger snake neurotoxins are selective antagonists of some nicotinic acetylcholine receptor subtypes and are widely used to study these receptors. The peptide neurotoxin azemiopsin, recently isolated from the venom of Azemipos feae, is a selective blocker of muscle-type nicotinic acetylcholine receptor. In order to reduce their toxicity and increase resistance under physiological conditions, we have encapsulated these toxins into nanomaterials. The study of nanomaterials after interaction with neurotoxins by the methods of transmission electron microscopy and dynamic light scattering revealed an increase in the size of nanoparticles, which indicates the inclusion of neurotoxins in nanomaterials.

Rationale Despite a long history of use in synaptic physiology, the lobster has been a neglected model for behavioral pharmacology. A restaurateur proposed that exposing lobster to cannabis smoke reduces anxiety and pain during the cooking process. It is unknown if lobster gill respiration in air would result in significant Δ9-tetrahydrocannabinol (THC) uptake and whether this would have any detectable behavioral effects. Objective The primary goal was to determine tissue THC levels in the lobster after exposure to THC vapor. Secondary goals were to determine if THC vapor altered locomotor behavior or nociception. Methods Tissue samples were collected (including muscle, brain and hemolymph) from Homarus americanus (N = 3 per group) following 30 or 60 min of exposure to vapor generated by an e-cigarette device using THC (100 mg/mL in a propylene glycol vehicle). Separate experiments assessed locomotor behavior and hot water nociceptive responses following THC vapor exposure. Results THC vapor produced duration-related THC levels in all tissues examined. Locomotor activity was decreased (distance, speed, time-mobile) by 30 min inhalation of THC. Lobsters exhibit a temperature-dependent withdrawal response to immersion of tail, antennae or claws in warm water; this is novel evidence of thermal nociception for this species. THC exposure for 60 min had only marginal effect on nociception under the conditions assessed. Conclusions Vapor exposure of lobsters, using an e-cigarette based model, produces dose-dependent THC levels in all tissues and reduces locomotor activity. Hot water nociception was temperature dependent, but only minimal anti-nociceptive effect of THC exposure was confirmed.

E-cigarette aerosol is a complex mixture of gases and particles with a composition that is dependent on the e-liquid formulation, puffing regimen, and device operational parameters. This work investigated mainstream aerosols from a third generation device, as a function of coil temperature (315-510 °F, or 157-266 °C), puff duration (2-4 s), and the ratio of propylene glycol (PG) to vegetable glycerin (VG) in e-liquid (100:0-0:100). Targeted and untargeted analyses using liquid chromatography high-resolution mass spectrometry, gas chromatography, in situ chemical ionization mass spectrometry, and gravimetry were used for chemical characterizations. PG and VG were found to be the major constituents (>99%) in both phases of the aerosol. Most e-cigarette components were observed to be volatile or semivolatile under the conditions tested. PG was found almost entirely in the gas phase, while VG had a sizable particle component. Nicotine was only observed in the particle phase. The production of aerosol mass and carbonyl degradation products dramatically increased with higher coil temperature and puff duration, but decreased with increasing VG fraction in the e-liquid. An exception is acrolein, which increased with increasing VG. The formation of carbonyls was dominated by the heat-induced dehydration mechanism in the temperature range studied, yet radical reactions also played an important role. The findings from this study identified open questions regarding both pathways. The vaping process consumed PG significantly faster than VG under all tested conditions, suggesting that e-liquids become more enriched in VG and the exposure to acrolein significantly increases as vaping continues. It can be estimated that a 30:70 initial ratio of PG:VG in the e-liquid becomes almost entirely VG when 60-70% of e-liquid remains during the vaping process at 375 °F (191 °C). This work underscores the need for further research on the puffing lifecycle of e-cigarettes.

RationaleDespite a long history of use in synaptic physiology, the lobster has been a neglected model for behavioral pharmacology. A restaurateur proposed that exposing lobster to cannabis smoke reduces anxiety and pain during the cooking process. It is unknown if lobster gill respiration in air would result in significant Δ9-tetrahydrocannabinol (THC) uptake and whether this would have any detectable behavioral effects.ObjectiveThe primary goal was to determine tissue THC levels in the lobster after exposure to THC vapor. Secondary goals were to determine if THC vapor altered locomotor behavior or nociception.MethodsTissue samples were collected (including muscle, brain and hemolymph) from Homarus americanus (N=3 per group) following 30 or 60 minutes of exposure to vapor generated by an e-cigarette device using THC (100 mg/mL in a propylene glycol vehicle). Separate experiments assessed locomotor behavior and hot water nociceptive responses following THC vapor exposure.ResultsTHC vapor produced duration-related THC levels in all tissues examined. Locomotor activity was decreased (distance, speed, time-mobile) by 30 min inhalation of THC. Lobsters exhibit a temperature-dependent withdrawal response to immersion of tail, antennae or claws in warm water; this is novel evidence of thermal nociception for this species. THC exposure for 60 minutes had only marginal effect on nociception under the conditions assessed.ConclusionsVapor exposure of lobsters, using an e-cigarette based model, produces dose-dependent THC levels in all tissues and reduces locomotor activity. Hot water nociception was temperature dependent, but only minimal anti-nociceptive effect of THC exposure was confirmed.

The electrochemical hydrogen evolution reaction (HER) is of great interest to advance fuel cell technologies. Although heterogeneous HER electrocatalysts are desired for practical energy devices, the development of molecular electrocatalysts is important to elucidate the mechanism and improve the activity of state-of-the-art HER catalysts. Inspired by the enzymatic HER process promoted by [NiFe] hydrogenases, we synthesized a bioinspired NiII electrocatalyst that produces H2 from CF3CO2H at low acid concentrations (–1. We propose that our NiII electrocatalyst follows a novel HER mechanism by undergoing a 2e– transfer process in a single step, followed by stepwise H+ transfer at low acid concentrations, while the increase in acid concentration changes the HER mechanism toward a concerted H+/e– transfer. Finally, we evaluated the HER activity of our catalyst by benchmarking its kinetic and thermodynamic parameters vs. other reported HER electrocatalysts.

The development of a water-soluble iridium catalyst enables the trifluoromethylation of polar small molecules and peptides in DMSO solution or aqueous media. The reaction was optimized in a microtiter plate format under ambient air, using commercial Langlois reagent as a CF3 radical source, blue LEDs for excitation, and using DPBS as solvent to provide up to 60% CF3- peptide.

This pre-specified analysis of DAPA-CKD assessed the impact of sodium-glucose cotransporter 2 inhibition on abrupt declines in kidney function in high-risk patients based on having chronic kidney disease (CKD) and substantial albuminuria. DAPA-CKD was a randomized, double-blind, placebo-controlled trial that had a median follow-up of 2.4 years. Adults with CKD (urinary albumin-to-creatinine ratio 200-5000 mg/g and estimated glomerular filtration rate 25-75 mL/min/1.73m2) were randomized to dapagliflozin 10 mg/day matched to placebo (2152 individuals each). An abrupt decline in kidney function was defined as a pre-specified endpoint of doubling of serum creatinine between two subsequent study visits. We also assessed a post-hoc analysis of investigator-reported acute kidney injury-related serious adverse events. Doubling of serum creatinine between two subsequent visits (median time-interval 100 days) occurred in 63 (2.9%) and 91 (4.2%) participants in the dapagliflozin and placebo groups, respectively (hazard ratio 0.68 [95% confidence interval 0.49, 0.94]). Accounting for the competing risk of mortality did not alter our findings. There was no heterogeneity in the effect of dapagliflozin on abrupt declines in kidney function based on baseline subgroups. Acute kidney injury-related serious adverse events were not significantly different and occurred in 52 (2.5%) and 69 (3.2%) participants in the dapagliflozin and placebo groups, respectively (0.77 [0.54, 1.10]). Thus, in patients with CKD and substantial albuminuria, dapagliflozin reduced the risk of abrupt declines in kidney function. HJLH and DC are co-primary authors. The DAPA-CKD Trial Committees and Investigators are listed in the Appendix.

The enantioselective hydroarylation of vinylarenes catalyzed by a chiral, non-racemic nickel catalyst is presented as a facile method to generate chiral 1,1-diarylethanes. These reactions proceed v...

Electrochemical proton reduction to produce hydrogen is considered a sustainable approach to shift the fossil fuel-based energy production toward renewable energy sources. Although the development of molecular electrocatalysts for the hydrogen evolution reaction (HER) has gained significant attention, most of these molecular catalysts require either strong acids or often operate at high proton concentration to achieve high turnover. Herein, we report the synthesis and charcterization of two NiII complexes, [(N2S2)Ni(MeCN)2](OTf)2 (1•(OTf)2) and (NCHS2)Ni(OTf)2 (2) bearing bioinspired 3,7-dithia-1,5(2,6)-dipyridinacyclooctaphane (N2S2) and 3,7-dithia-1(2,6)-pyridina-5(1,3)-benzenacyclooctaphane (NCHS2) ligands, respectively, along with their electrochemical HER in a non-aqueous electrolyte. Our Ni complexes show high turnover frequencies greater than 200,000 s–1 in the presence of 0.043 M of trifluoroacetic acid with ≥1 M of water present. Under these electrochemical conditions, 2 exhibited 2.5-fold faster kinetics at 240 mV lower overpotential than that of 12+. Furthermore, 2 initiates electrochemical proton reduction at the potential where NiII/I redox couple occurs, whereas the similar HER electrocatalysis carried out by 12+ was observed at the potential for the NiI/0 redox couple. The electrochemical analysis revealed that 2 undergoes an uncommon HER mechanism proposed to involve a NiIII–hydride species – a typical pathway followed by [NiFe] hydrogenase enzymes, upon activating the C–H bond of the coordinating NCHS2 ligand, and the resulting organometallic Ni complex is proposed to be the active HER electrocatalyst. This organometallic Ni complex derivative, [(NCS2)Ni(MeCN)2]2+ (5) was synthesized independently and its performance for the HER supports the proposed HER mechanism for 2. Additionally, electron paramagnetic resonance (EPR) spectroscopy was employed to probe the accessibility to NiI and NiIII species proposed as intermediates in the described HER mechanisms. Importantly, comparative catalytic Tafel plots were constructed to benchmark the HER activity of 12+ and 2 versus previously reported known Ni-based HER electrocatalysts. Overall, the organometallic (NCS2)Ni system reported below represents a novel bioinspired molecular HER electrocatalyst that exhibits a high turnover frequency and more closely resembles the NiI/NiIII HER mechanism proposed to pe operative in [NiFe] hydrogenases.

A series of (N2P2)NiII complexes (N2P2 = P,P’-ditertbutyl-2,11-diphosphonito[3.3](2,6)pyridinophane) stabilized by a modified tetradentate pyridinophane ligand containing two phosphonite groups were synthesized and characterized. Cyclic voltammetry (CV) studies revealed the accessibility of the NiI oxidation state at moderate redox potentials for these NiII complexes. In situ EPR, low-temperature UV-vis, and electrochemical studies were employed to detect the formation of NiI species during the reduction of NiII precursors. Furthermore, the [(N2P2)NiI(CNtBu)](SbF6) complex was isolated upon reduction of the NiII precursor with 1 equiv of CoCp2, and was characterized by EPR and X-ray photoelectron spectroscopy (XPS). Finally, the (N2P2)NiIIBr2 complex acts as an efficient catalyst for the Kumada cross-coupling of an aryl halide with an aryl or alkyl Grignard, suggesting that the N2P2 ligand can support the various Ni species involved in the catalytic C-C bond formation reactivity.

Objective Infants with Congenital Heart Disease (CHD) are at risk for developmental delays, though the mechanisms of brain injury that impair development are unknown. Potential causes could include cerebral hypoxia and cerebrovascular instability. We hypothesized that we would detect significantly reduced cerebral oxygen saturation and greater cerebrovascular instability in CHD infants compared to the healthy controls. Methods We performed a secondary analysis on a sample of 43 term infants (28 CHD, 15 healthy controls) that assessed prospectively in temporal cross-section before or at 12 days of age. CHD infants were assessed prior to open-heart surgery. Cerebral oxygen saturation levels were estimated using Near-Infrared Spectroscopy, and cerebrovascular stability was assessed with the response of cerebral oxygen saturation after a postural change (supine to sitting). Results Cerebral oxygen saturation was 9 points lower in CHD than control infants in both postures (β = -9.3; 95%CI = -17.68, -1.00; p = 0.028), even after controlling for differences in peripheral oxygen saturation. Cerebrovascular stability was significantly impaired in CHD compared to healthy infants (β = -2.4; 95%CI = -4.12, -.61; p = 0.008), and in CHD infants with single ventricle compared with biventricular defects (β = -1.5; 95%CI = -2.95, -0.05; p = 0.04). Conclusion CHD infants had cerebral hypoxia and decreased cerebral oxygen saturation values following a postural change, suggesting cerebrovascular instability. Future longitudinal studies should assess the associations of cerebral hypoxia and cerebrovascular instability with long-term neurodevelopmental outcomes in CHD infants.

Thioredoxin (Trx), a small redox protein, exhibits thermal stability at high temperatures regardless of its origin, including psychrophiles. Trxs have a common structure consisting of the central β-sheet flanked by an aliphatic cluster on one side and an aromatic cluster on the other side. Although the roles of aromatic amino acids in the folding and stability of proteins have been studied extensively, the contributions of aromatic residues to the stability and function of Trx, particularly Trxs from cold-adapted organisms, have not been fully elucidated. This study examined the roles of aromatic amino acids in the aromatic cluster of a Trx from the psychrophilic Arctic bacteriumSphingomonassp. PAMC 26621 (SpTrx). The aromatic cluster of SpTrx was comprised of W11, F26, F69, and F80, in which F26 at the β2 terminus was buried inside. The substitution of tyrosine for F26 changed the SpTrx conformation substantially compared to that of F69 and F80. Further biochemical and spectroscopic investigations on F26 showed that the F26Y, F26W, and F26A mutants resulted in structural instability of SpTrx in both urea- and temperature-induced unfolding and lower insulin reduction activities. The Trx reductase (SpTR) showed lower catalytic efficiencies against F26 mutants compared to the wild-type SpTrx. These results suggest that buried F26 is essential for maintaining the active-site conformation of SpTrx as an oxidoreductase and its structural stability for interactions with SpTR at colder temperatures.

The catalytic conversion of biomass-derived furfural into 1,5-pentadiol has become an attractive study. However, the design of effective catalyst for converting furfural into 1,5-pentadiol under mild reaction condition remained a great challenge. This work reported the hydrogenolysis of furfural into 1,5-pentadiol using the Pt nanoparticles supported silicalite-1 as effective and recyclable catalyst. The Pt/silicalite-1 catalyst was synthesized by the reaction between tetraethyl orthosilicate and tetra-n-propyl ammonium hydroxide, and characterized using XRD, SEM, and ICP-OES. The Pt/silicalite-1 catalyst exhibited highly active for the hydrogenolysis of furfural into 1,5-pentadiol, with a high yield of 60% at room temperature for 12 h using NaBH4 as reducing agent. In addition, the catalyst can reuse five times without loss significantly catalytic activity.

Summary Fluorescent probes are important tools in cellular imaging. However, many readily available small-molecule imaging probes are either cytotoxic or easily photobleached and thus not compatible with lengthy live cell or tissue-imaging experiments. One particularly limited field of application is neuroscience, in which small-molecule probes for live cell imaging at the brain tissue level are highly scarce. Here, we describe a rapid synthetic route to generate a series of nuclear stains that enable experiments with live brain cells (i.e., water solubility, cell permeability, high quantum yield, high photostability, and most important, negligible cytotoxicity). As a proof of principle, we demonstrate that these probes are compatible with ex vivo and in vivo nuclear labeling experiments, including retrograde transport to monitor and map certain brain regions of the mouse model. The structural versatility and superior non-cytotoxic properties of these probes may suggest their potential use in labeling and tracing of neuronal populations.

Substituted pyrans and furans are core structures found in a wide variety of natural products and biologically-active compounds. Herein, we report a practical and mild catalytic method for the synthesis of substituted pyrans and furans using molecular iodine, a simple and inexpensive catalyst. The method described herein is performed in solvent-free conditions in ambient temperature and atmosphere, thus offering a facile and green alternative to currently available reaction protocols. A combination of experimental studies and high‐level DFT calculations revealed interesting mechanistic insights of this seemingly simple reaction.

Cold-adapted enzymes maintain correct conformation at their active sites despite their intrinsically flexible structures. The psychrophilic Arctic bacterium Sphingomonas sp. PAMC 26621 has two glucose 6-phosphate dehydrogenase (G6PD) isozymes, SpG6PD1 involved in the Entner-Doudoroff pathway and SpG6PD2 in the oxidative pentose phosphate pathway. Structural modeling of SpG6PD1 showed that the hydroxyl group of Tyr177 participates in substrate binding by forming a hydrogen bond with the phosphate group of glucose 6-phosphate, whereas in SpG6PD2, a Phe residue is present in the corresponding position of Tyr177. In this study, we investigated how subtle differences in aromatic residues in the substrate-binding pocket of SpG6PD1 affect enzymatic activity and stability. Mutations of Tyr177 to Ala, His, Phe, and Trp caused increases in the rigidity of the SpG6PD1 structure. Particularly, mutants Y177F and Y177W showed increased thermal stabilities compared to wild-type (WT) but 3- and 15-fold lower catalytic efficiencies, respectively. However, mutants Y177A and Y177H became heat-labile at moderate temperatures. These results indicate that an aromatic residue (Tyr or Phe) is necessary for the substrate-binding pocket of SpG6PD1; Tyr with its hydroxyl group is preferred for enzymatic activity, whereas the more hydrophobic Phe is preferred for thermal stability. Substitutions of bulky Trp for Tyr or Phe at this position resulted in substantial loss of activity. Our study suggests that delicate adjustment of aromatic residues can regulate the activity and stability of psychrophilic G6PD isozymes involved in different metabolic pathways.

Since 2008, fine gauge (≤ 35 μm diameter) copper (Cu) wire has been rapidly replacing fine gauge gold (Au) wire in consumer, commercial, and industrial products [2–4]. The first wave of Cu wire products used bare, uncoated Cu wire which is soon to known having Cu-Al IMC corrosion induced by mobile chlorine ions in the epoxy mold compound system when IC parts are subjected to moisture related package stress tests such as biased HAST (Highly Accelerated Stress Test) [1–7]. Additionally, when comparing to Au wires, the 2nd bond process window of bare Cu wire can be very narrow and becomes a concern of moving into HVM (high volume manufacturing) [8]. Thus, palladium-coated Cu (PdCu) wire was introduced to the semiconductor assembly market aiming to provide more margin of passing biased HAST and enhance 2nd bond process capability [9–13]. However, the use of Pd-Cu wire is not a panacea to all Cu wire bond problems. One unique anomaly for Pd-Cu wire is the Cu ball void [1] which is observed only with Pd-Cu and not bare Cu ball bonds during HTSL (high temperature storage life) tests. The mechanism of forming Cu ball voids was proven to be the galvanized corrosion mechanism with Pd-Cu coupling. Significant factors affecting the formation rate of Cu ball voids are found to be baking temperature, EFO current settings, bonding parameters and mold compound additives (sulfur). Both anodic and cathodic chemical reactions will be proposed for Cu voids in this paper. Even though Cu void can be considered as a cosmetic defect for the majority of application since the peak temperature of device mission profile is always no larger than 175C. The application at extreme high temperature (for example, 190C) can actually cause electrical failure at the ball bon region due to the Cu void formation in terms of size and location at the Cu-Al IMC region. The main effect is due to the selected mold compound having high amount of metallic adhesion promoter which is sulfur-based and extensive high temperature storage test condition (190C). The FIB/SEM picture of failing ball bond due to Cu voids from this particular device will be presented in the paper. Thus, a newly developed doped Cu wire without Pd coating has been proposed by many wire suppliers to overcome Cu ball voids. However, doped Cu wires without Pd coating have suffered the same high volume manufacturing issues observed by bare Cu wires. For example, short tail and mean time between assist (MTBA) for doped Cu wires without Pd coating are both as poor as bare Cu wires. We will present high temperature storage test results obtained by doped PdCu wires in this paper. To balance high volume manufacturing issues and Cu void formation, doped PdCu wires are also proposed recently. Several doped PdCu wires whose extensive high temperature storage results (220C) will be presented in this paper. The worst case mold compound with high amount of sulfur based adhesion promoter has been used to test the effectiveness of these new wire types. At such harsh testing condition, there is one doped PdCu wire in our test can actually survive without electrical failed ball bond due to Cu voids. Factors of effectiveness of doped PdCu wires will be discussed in this paper. Authors have chosen to focus on Cu voids at both 1st bond (ball bond) and 2nd bond (wedge). 20 um wire diameter has been used for all test vehicle in this study. All controlling factors of eliminating Cu voids will surely be included at the end of this paper.

Electrospray ionization (ESI) mass spectrometry (MS) is a crucial method for rapidly determining the interactions between small molecules and proteins with ultrahigh sensitivity. However, nonvolatile molecules and salts that are often necessary to stabilize the native structures of protein–ligand complexes can readily adduct to protein ions, broaden spectral peaks, and lower signal-to-noise ratios in native MS. ESI emitters with narrow tip diameters (∼250 nm) were used to significantly reduce the extent of adduction of salt and nonvolatile molecules to protein complexes to more accurately measure ligand–protein binding constants than by use of conventional larger-bore emitters under these conditions. As a result of decreased salt adduction, peaks corresponding to protein–ligand complexes that differ in relative molecular weight by as low as 0.06% can be readily resolved. For low-molecular-weight anion ligands formed from sodium salts, anion-bound and unbound protein ions that differ in relative mass by 0.2% were completely baseline resolved using nanoscale emitters, which was not possible under these conditions using conventional emitters. Owing to the improved spectral resolution obtained using narrow-bore emitters and an analytically derived equation, Kd values were simultaneously obtained for at least six ligands to a single druggable protein target from one spectrum for the first time. This research suggests that ligand–protein binding constants can be directly and accurately measured from solutions with high concentrations of nonvolatile buffers and salts by native MS., Nanoscale emitters in native MS significantly improve measurements of ligand−protein interactions. The binding affinities of six ligands can be rapidly obtained simultaneously with high sensitivity.

Reducing chemical fertilizer while remaining high crop yield has become a trend of agricultural practice. The purpose of this study was to investigate the effects of nitrogen (N) input on the structure of the fungal community and mycorrhizal inoculum potential in rhizosphere of Curcuma longa, aiming to minimize the use of chemicals and optimize the effect of biofertilizer for sustainable turmeric farming. For this, a field study was conducted in two successive years 2015 and 2016 with applications of varrying N fertilizer rates N0 (0 kgN ha−1 y−1), N150 (150 kgN ha−1 y−1), N350 (350 kgN ha−1 y−1), and N500 (500 kgN ha−1 y−1) in combination with mycorrhizal biofertilizer on turmeric plants in Hung-Yen. Rhizosphere soils were then analyzed for the abundance of predominant fungal taxon based on amplicon sequencing of rDNA internal transcribed spacer regions. Metagenomic results indicated significant effects of N inputs on rhizosphere fungal communities composition, with dominance of ascomyceteous fungi under optimized N levels, whereas basidiomycetous fungi were more abundant under higher N input. Operational taxonomic units relating to the predominantly abundant genus Glomus were found apparently in higher proportion under optimized N inputs (N150). The results demonstrate an enhanced productivity and icreased mycorrhizal inoculating potential by appropriated N fertilizer application in turmeric rhizosphere.

Sugar alcohols (polyols) are abundant carbohydrates in lichen-forming algae and transported to other lichen symbionts, fungi, and bacteria. Particularly, ribitol is an abundant polyol in the lichen Cetraria sp. Polyols have important physiological roles in lichen symbiosis, but polyol utilization in lichen-associated bacteria has been largely unreported. Herein, we purified and characterized a novel ribitol dehydrogenase (RDH) from a Cetraria sp.-associated bacterium Sphingomonas sp. PAMC 26621 grown on a minimal medium containing D-ribitol (the RDH hereafter referred to as SpRDH). SpRDH is present as a trimer in its native form, and the molecular weight of SpRDH was estimated to be 39 kDa by SDS-PAGE and 117 kDa by gel filtration chromatography. SpRDH converted D-ribitol to D-ribulose using NAD+ as a cofactor. As far as we know, SpRDH is the first RDH belonging to the medium-chain dehydrogenase/reductase family. Multiple sequence alignments indicated that the catalytic amino acid residues of SpRDH consist of Cys37, His65, Glu66, and Glu157, whereas those of short-chain RDHs consist of Ser, Tyr, and Lys. Furthermore, unlike other short-chain RDHs, SpRDH did not require divalent metal ions for its catalytic activity. Despite SpRDH originating from a psychrophilic Arctic bacterium, Sphingomonas sp., it had maximum activity at 60°C and exhibited high thermal stability within the 4-50°C range. Further studies on the structure/function relationship and catalytic mechanism of SpRDH will expand our understanding of its role in lichen symbiosis.

No magnetic loss during the absorption process is a lack of conductive polymers, while not lightweight is a drawback of magnetic materials to be potential microwave absorbers. A hybrid of magnetic material and conductive polymer is a good resolution for above issues. In this work, composites of BiFe0.8Co0.1Mn0.1O3 (BF) and multi-walled carbon nanotubes (MWCNTs, named as MW) were prepared by a hydrothermal method. Then, the in-situ polymerization method was used to decorate polythiophene on the MW/BF composites. The formation of polythiophene@MW/BF composites and their magnetic, electromagnetic properties were investigated using XRD, XPS, FE-SEM, EDS, and VNA. The composite with MW and polythiophene significantly tuned the microwave dissipation features of the polythiophene@MW/BF composites. In the measurement range of 12.4–18 GHz, the results revealed that the composite with 20 percent of MW (named as P@20 MW/BF) has a minimum reflection loss of −19 dB at frequency f = 13 GHz for a thickness of 2 mm. The maximum effective absorption bandwidth was also found for the P@20 MW/BF composite as 2.6 GHz. Enhancement in microwave absorption performance arises from the balance between magnetic loss and dielectric loss. Overall, the introduction of three-layer polythiophene/MW/BF composites provides potential microwave absorbers for application in the range of 12.4–18 GHz.

The carbonyl–olefin metathesis reaction could facilitate rapid functional group interconversion and allow construction of complicated organic structures. Herein, we demonstrate that elemental iodine, a very simple catalyst, can efficiently promote this chemical transformation under mild reaction conditions. Our mechanistic studies revealed intriguing aspects of the activation mode via molecular iodine and the iodonium ion that could change the previously established perception of catalyst and substrate design for the carbonyl–olefin metathesis reaction.