VI Compounds Research Articles

An ISG15-Based High-Throughput Screening Assay for Identification and Characterization of SARS-CoV-2 Inhibitors Targeting Papain-like Protease.

Emergence of newer variants of SARS-CoV-2 underscores the need for effective antivirals to complement the vaccination program in managing COVID-19. The multi-functional papain-like protease (PLpro) of SARS-CoV-2 is an essential viral protein that not only regulates the viral replication but also modulates the host immune system, making it a promising therapeutic target. To this end, we developed an in vitro interferon stimulating gene 15 (ISG15)-based Förster resonance energy transfer (FRET) assay and screened the National Cancer Institute (NCI) Diversity Set VI compound library, which comprises 1584 small molecules. Subsequently, we assessed the PLpro enzymatic activity in the presence of screened molecules. We identified three potential PLpro inhibitors, namely, NSC338106, 651084, and 679525, with IC50 values in the range from 3.3 to 6.0 µM. These molecules demonstrated in vitro inhibition of the enzyme activity and exhibited antiviral activity against SARS-CoV-2, with EC50 values ranging from 0.4 to 4.6 µM. The molecular docking of all three small molecules to PLpro suggested their specificity towards the enzyme's active site. Overall, our study contributes promising prospects for further developing potential antivirals to combat SARS-CoV-2 infection.

Ftir Spectroscopy as a Convenient Tool for Detection and Identification of Airborne Cr(Vi) Compounds Arising from Arc Welding Fumes

Ftir Spectroscopy as a Convenient Tool for Detection and Identification of Airborne Cr(Vi) Compounds Arising from Arc Welding Fumes

Investigation of the influence of electromagnetic field strength on the quality of water purification from heavy metals by ferritization method

To date, one of the components of the global problem of water pollution has been the uncontrolled discharge of wastewater from industrial enterprises that use in their work technological solutions of heavy metals, including galvanic. Among the main components of wastewater generated in galvanic industrial enterprises, about 70% is zinc and its compounds, and the most toxic of the heavy metals contained in process solutions are Cr VI compounds. In view of this, it is important to improve the ferritization treatment of wastewater from zinc and chromium ions. A laboratory installation for the ferritization process with electromagnetic pulse activation (EMI) has been developed. This method of activation provides not only a reduction in energy costs, but also the appropriate degree of extraction of heavy metal ions, which allows you to get an aqueous solution that can be used in a circulating water supply system, and sludge disposed of as additives for alkaline cements. The influence of the strength of the electromagnetic field on the degree of extraction of zinc and chromium ions from wastewater by ferritization has been studied. It is determined that the best degree of purification from heavy metal ions is achieved at an electromagnetic field of 0.14T.

Calcium Vapor Reduction of Group V and VI Metal Oxide Compounds

We have studied calcium vapor reduction of Group V and VI metal oxide compounds (Ta2O5, Nb2O5, WO3, MoO3, MgWO4, MgMoO4, and CaMoO4) at temperatures from 800 to 860°C and residual argon pressures from 5 to 10 kPa. The products of the reduction of the Group V metal compounds had the form of a homogeneous mixture corresponding to the reaction stoichiometry. After the reduction of the Group VI compounds under similar conditions, we observed spatial separation of the reaction products: most of the reductant metal oxide was located beyond the reaction zone. In the initial stage of the reduction of MgWO4 and MgMoO4, calcium substitutes for magnesium in these compounds. Together with calcium oxide, the magnesium oxide forms a layer on the surface of the reactants. Analysis of our results suggests that the calcium vapor reduction of the Group VI metal oxide compounds is likely to follow the electronically-mediated reaction mechanism.

Nickel compounds in the workplaces: Occupations and activities involving high-risk exposures in Italy.

Nickel (Ni) compounds have been classified as carcinogenic to humans. The aim of the study is to evaluate exposures to Ni at workplaces in Italy. Data on Ni compounds were collected from an occupational exposure registry. Statistical analysis was carried out for exposure-related variables. The number of workers potentially exposed was estimated for selected industrial sectors. Concurrent exposures with other occupational carcinogens were investigated using two-step cluster analysis. Overall 10 083 measurements were analyzed during 1996-2016, having a geometric mean of 2.93 μg/m3 . Most exposures occurred in manufacture of metal products (50%) and among metal finishing machine operators (46%). A total of 56 046 workers potentially exposed to Ni was estimated. Concurrent exposures were frequently detected, mainly with chromium VI and cobalt compounds. Systematic recording of occupational exposures provides a data source that allows recognition of high risk situations for workers' health and helps improve exposure assessment in epidemiologic studies.

Antibacterial and DNA cleavage activity of carbonyl functionalized N-heterocyclic carbene-silver(I) and selenium compounds

The article describes syntheses and characterizations of carbonyl functionalized benzimidazolium salts, I–IV. While salts I–III are unstable at room temperature, salt IV remained stable and was further utilised to form N-heterocyclic carbene (NHC) compounds of silver(I), V and VI, and selenium compound, VII respectively. Compounds IV–VII were tested for their antibacterial potential against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Salt IV shows a very low inhibition potential (minimum inhibitory concentration, MIC 500 μg/mL) compared to the respective silver(I)-NHC, V and VI (MIC 31.25 μg/mL against both, E. coli and S. aureus) and selenium compound, VII (MIC 125 μg/mL against E. coli and 62.50 μg/mL against S. aureus). In DNA cleavage abilities, all the test compounds cleave DNA in which the VII cleaves the DNA at the faster rate. Meanwhile, the silver(I)-NHC complexes V and VI act at the same mode and pattern of DNA cleavage while VII is similar to IV.

Zn–VI quasiparticle gaps and optical spectra from many-body calculations

The electronic band structures of hexagonal ZnO and cubic ZnS, ZnSe, and ZnTe compounds are determined within hybrid-density-functional theory and quasiparticle calculations. It is found that the band-edge energies calculated on the (Zn chalcogenides) or GW (ZnO) level of theory agree well with experiment, while fully self-consistent QSGW calculations are required for the correct description of the Zn 3d bands. The quasiparticle band structures are used to calculate the linear response and second-harmonic-generation (SHG) spectra of the Zn–VI compounds. Excitonic effects in the optical absorption are accounted for within the Bethe–Salpeter approach. The calculated spectra are discussed in the context of previous experimental data and present SHG measurements for ZnO.

Density functional theory based tight binding study on theoretical prediction of low-density nanoporous phases ZnO semiconductor materials

Polymorphs or phases - different inorganic solids structures of the same composition usually have widely differing properties and applications, thereby synthesizing or predicting new classes of polymorphs for a certain compound is of great significance and has been gaining considerable interest. Herein, we perform a density functional theory based tight binding (DFTB) study on theoretical prediction of several new phases series of II-VI semiconductor material ZnO nanoporous phases from their bottom-up building blocks. Among these, three phases are reported for the first time, which could greatly expand the family of II- VI compound nanoporous phases. We also show that all these generally can be categorized similarly to the aluminosilicate zeolites inorganic open-framework materials. The hollow cage structure of the corresponding building block ZnkOk (k= 9, 12, 16) is well preserved in all of them, which leads to their low-density nanoporous and high flexibility. Additionally the electronic wide-energy gap of the individual ZnkOk is also retained. Our study reveals that they are all semiconductor materials with a large band gap. Further, this study is likely to be the common for II-VI semiconductor compounds and will be helpful for extending their range of properties and applications.

1H and 1T polymorphs, structural transitions and anomalous properties of (Mo,W)(S,Se)2 monolayers: first-principles analysis

Among the 1H and 1T structures exhibited by monolayers of transition metal dichalcogenides, the group VI compounds MX2 (M = Mo, W and X = S, Se) largely occur in the 1H form. Recently, transformation of the 1H form to the 1T form with metallic electronic structure at high temperatures was demonstrated in MoS2 with Re substitution and electron irradiation by Lin et al (2014 Nat. Nanotechnology 9 391). Here, we use first-principles calculations to determine the energy landscape associated with the 1H to 1T phase transition, predict novel 1T structures and relate the observed by Lin et al (2014 Nat. Nanotechnology 9 391) intermediate structures to structural instabilities of the 1T structure of MX2 compounds. We show that the metallic centrosymmetric 1T (c 1T ) structure of these compounds is unstable with respect to dimerization or trimerization of metal atoms, leading to a competing metallic 1T form and ferroelectric semiconducting 1T form respectively. While the former is a more stable 1T form of MoSe2, WS2 and WSe2, the latter is a more stable 1T form of MoS2 exhibiting rich ferroelectric dipolar domain structure. In the vicinity of metal-semiconductor transitions, their semiconducting forms are shown to exhibit an anomalous response to electric fields. To facilitate the experimental verification of these subtle features of the 1T forms of MX2 monolayers, we present comparative analysis of their vibrational properties, and identify their Raman and infra-red spectroscopic signatures.

(Invited) Emerging Oxide Nanowires: Creation Concept and Their Promises for Novel Nanoscale Devices

Self-assembled one-dimensional “ Nanowires ” have attracted much attention due to not only the fundamental interests in nanoscale-confided physical properties but also novel nano-device applications, where existing nanomaterials have not been applicable. Nanowires are attracting the interests of researchers from diverse research communities ranged from physics, chemistry, material science, electrical engineering, chemical engineering and others. Group VI and III-V compounds nanowires have demonstrated their great promises for exploring fundamental physical properties at nanoscale and also the feasibility of diverse nano-device applications. Although metal oxides exhibit their rich variety of physical properties including photo catalysts, ferroelectric, ferromagnetic, high-Tc superconducting, memristive switching, which are hardly attainable to other materials, compared with group VI and III-V compounds nanowires, the feasibility of functional oxide nanowires has been strongly limited due to the absence of fabrication method for various transition metal oxide nanowires. Here we demonstrate i) “Creation Concept” for well-defined oxide nanowires via vapor-liquid-solid (VLS) mechanisms, and ii) the memristive switching phenomena within a single oxide nanowire down to 10 nm scale.We have succeeded to fabricate a well-defined single crystalline metal oxide nanowire by controlling precisely formation environments. When comparing with MD simulations as to VLS growth, the importance of material transport via the metal catalysts has been found. Especially, we have found that the difference between LS interface and VS interface on the critical nucleation size essentially allows us to perform VLS nanowire growth. This knowledge can be expanded to discover novel metal oxide nanowires via VLS mechanisms. Next, we have constructed highly stable RS junctions comprised of Pt/single oxide nanowire /Pt. The nanowire memristor exhibited the endurance up to 108 by utilizing self-assembled nanowires and well-defined nano-gap electrodes. In addition, information as to the memristive switching including the carrier type for memristive switching and the spatial switching location, have been extracted by the present nanowire memristor, which had been buried in conventional memristors. We believe that the presented approaches by utilizing self-assembled oxide nanowire/metal junctions offer an important system and platform for investigating not only nanoscale confined physical properties of transition metal oxides but also exploring exciting novel nano-devices with other electric materials, which had not been possible.

Occupational exposure to chrome VI compounds in French companies: results of a national campaign to measure exposure (2010-2013).

A campaign to measure exposure to hexavalent chromium compounds was carried out in France by the seven CARSAT chemistry laboratories, CRAMIF laboratory, and INRS over the 2010-2013 period. The survey included 99 companies involved in various activity sectors. The inhalable fraction of airborne particles was sampled, and exposure levels were determined using ion chromatography analysis combined with post-column derivatization and UV detection. The quality of the measurement results was guaranteed by an inter-laboratory comparison system involving all the laboratories participating in this study. Exposure levels frequently exceeded the French occupational exposure limit value (OELV) of 1 µg m(-3), in activities such as thermal metallization and manufacturing and application of paint in the aeronautics sector. The results also reveal a general trend for a greater proportion of soluble Chromium VI (Cr VI) compounds compared with insoluble compounds. Qualitative and quantitative information relating to the presence of other metallic compounds in the air of workplaces is also provided, for example for Cr III, Ni, Fe, etc. The sampling strategy used and the measurement method are easy to implement, making it possible to check occupational exposure with a view to comparing it to an 8 h-OELV of 1 µg m(-3).

0378 Occupational exposure to carcinogens in New Zealand

ObjectivesTo provide a detailed assessment of the extent and industrial distribution of workplace carcinogens in New Zealand, and to identify key industries and key carcinogens for which intervention would result...

Antioxidant activity of phenolic compounds identified in sunflower seeds

The antioxidant activity and phenolic compound profiles of six fractions (I–VI) obtained from sunflower seed extract were studied. HPLC–MS(ESI) analysis was applied for quantitative and qualitative determination of phenolic compounds of the fractions. The antioxidant activity of the fractions was studied in terms of their ability to scavenge DPPH· and ABTS·+ and to reduce Fe3+/ferricyanide complex to the ferrous form and was expressed as EC50, TEAC and reducing power values, respectively. The results of all antioxidant activity tests showed good correlations among each other and with the phenolic contents for the individual fractions. The fractions IV–VI were characterized by high antioxidant activity. 5-O-Caffeoylquinic acid was a predominant compound of fractions IV and V, while dicaffeoylquinic acid isomers and caffeoyl-dimethoxycinnamoylquinic acid isomers accounted for 76.6 % of phenolic compounds of fraction VI. Ferulic acid, p-coumaroylquinic acid isomers, ferulic acid dehydrotrimer isomers and some quercetin derivatives were also identified. The highest content of those compounds was noted in fraction III.

Electrical and structural properties of Bi2Te3 and Sb2Te3 thin films grown by the nanoalloying method with different deposition patterns and compositions

Thin films of Bi2Te3 and Sb2Te3 were synthesized by the nanoalloying approach, which has recently been proven to yield V–VI compounds with good thermoelectric properties and has several advantages over “conventional” growth on hot substrates. Firstly, repeating layers of the elements Bi, Sb and Te with a thickness in the range between 0.2 nm and 2.4 nm were deposited on BaF2 (111) substrates in an MBE system at room temperature with different deposition patterns for different samples, i.e. in bilayer and quintuple stacks, with different starting layer thicknesses and different Te contents. Subsequently, the element layer stacks were annealed in order to induce crystallization and compound formation of Bi2Te3 and Sb2Te3 thin films. The annealed thin films were characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The transport properties, i.e. electrical conductivities, carrier concentrations, carrier mobilities, Seebeck coefficients and thermal conductivities, were determined at room temperature for several sets of starting layer thicknesses and deposition patterns depending on the Te content. The texture was found to be strongly influenced by the starting thicknesses of the elemental layers in the deposition pattern. Results of temperature dependent measurements of the Seebeck coefficient and electrical conductivity on one sample of nanoalloyed Bi2Te3 and Sb2Te3 together with results from temperature dependent in situ XRD investigations are presented.

Fully Computational Lead-Development of Fluoro-Olefin Polymerization Catalysts

Coordinative polymerization of fluorinated olefins is still a challenging task. We analyzed the catalytic properties of diimido chromium VI compounds computationally by density functional methods. It was found that reactivity predictions depend strongly on the density functional chosen for the computations. Therefore, DFT calculations were calibrated to high level wave function theory calculations. Then geometrical parameters, which can be tuned by a ligand, were scanned to elucidate their influence on the catalytic activity. Having arrived at an optimal parameter set, we randomly assembled chromium complexes from a fragments database and automatically checked for their activities. This led to the proposal of three exemplary catalyst candidates.

Pd nanoparticles supported mesoporous γ-Al 2O 3 film as a reusable catalyst for reduction of toxic Cr VI to Cr III in aqueous solution

Pd nanoparticles (NPs) were generated inside the nanocrystalline mesoporous γ-Al 2O 3 films of thickness ∼2 μm. The support γ-Al 2O 3 films were prepared from boehmite sols derived from Al-alkoxide in presence of CTAB. The BET surface area (171 m 2g −1) and pore size (4.3 nm) of the undoped γ-Al 2O 3 films were found to be decreased to 139 m 2g −1 and 3.5 nm respectively after incorporation of Pd NPs. The films were characterized by GIXRD, cross-sectional FESEM, and TEM. TEM/GIXRD confirmed the existence of uniformly dispersed Pd NPs inside the γ-Al 2O 3 films. The Pd NPs (average size ∼4.1 nm)-incorporating mesoporous γ-Al 2O 3 films were used as catalyst to reduce toxic Cr VI compounds to non-toxic Cr III in presence of formic acid as reducing agent at different temperatures (30, 40, 50 and 60 °C). This catalytic reduction process was monitored by UV–visible spectrometer. The rate constant value for the reduction was estimated to be 0.085 min −1 at 50 °C. The same catalytic film can be used for three consecutive cycles by simple washing with water. The catalytic property started to deteriorate after the third cycle. The original catalytic property can be restored fully after heat-treatment of the used films at 300 °C in nitrogen atmosphere.

Lung cancer risk associated with occupational exposure to nickel, chromium VI, and cadmium in two population‐based case–control studies in Montreal

Nickel, chromium VI, and cadmium have been identified as lung carcinogens in highly exposed cohorts. The purpose of this study was to examine the etiological link between lung cancer and these metals in occupations, that usually entail lower levels of exposure than those seen in historical cohorts. Two population-based case-control studies were conducted in Montreal, from 1979 to 1986 and from 1996 to 2001, comprising 1,598 cases and 1,965 controls. A detailed job history was obtained to evaluate lifetime occupational exposure to many agents, including nickel, chromium VI, and cadmium compounds. Lung cancer odds ratios were increased only among former or non-smokers: 2.5 (95% CI: 1.3-4.7) for nickel exposure, 2.4 (95% CI: 1.2-4.8) for chromium VI, and 4.7 (95% CI: 1.5-14.3) for cadmium. The metals did not increase risk among smokers. While excess risks due to these metal compounds were barely discernable among smokers, carcinogenic effects were seen among non-smokers.

Structural properties and phase transformations under pressure of XTe compounds (X = Be, Mg, and Ca): The role of the exchange–correlation potential

We have performed first principles total energy calculations to investigate the structural properties and possible phase transitions under pressure of IIA–VI compounds: BeTe, MgTe and CaTe. We have considered the following possible structures: rock-salt, nickel arsenide, cesium chloride, zinc-blende, and in some cases wurtzite. Calculations are done using the periodic density functional theory. We employ the full potential linearized augmented plane wave method as implemented in the wien2k code. The exchange and correlation potential energies are treated according to the generalized gradient approximation (GGA) using the Perdew, Burke, Ernzerhof (PBE) parameterization, and the local density approximation (LDA). Our results show that the GGA calculations correctly predict the ground state structure of all three binary compounds: zinc-blende for BeTe, wurtzite/zinc-blende for MgTe, and rock-salt for CaTe. Under pressure, BeTe and MgTe transform to the nickel arsenide structure, while CaTe transforms from rock-salt to cesium chloride. Slightly different results are found using the LDA approximation. We discuss the role of the ionicity in the difference between the LDA and GGA results.

Formation and activation of defects in films of A IV B VI compounds in the process of growing from vapor phase

Formation and activation of defects in films of A IV B VI compounds in the process of growing from vapor phase

Comparative Study of a CsI and a ZnSe(Te/O) Scintillation Detector’s Properties for a Gamma-ray Measurement

A ZnSe crystal based on a II -VI compound semiconductor has various physical properties: electroluminescent, photoelectric, luminescent and scintillation. Activated ZnSe crystals are highly-efficient scintillators, and they are already being applied to the detecting units of a X-ray introscopy and a dosimetric system. ZnSe-based scintillators have a high absolute light output, and their radiation spectra matches well with the Si-photodiode spectral sensitivity.The present study was performed by using a polished ZnSe and CsI(Tl). ZnSe is a low-density crystal(5.42 g/cm3). The emission wavelength of ZnSe(Te) is 610 nm and ZnSe(O) is 592 nm. We have fabricated 10×10×1 mm and 10×10×2 mm ZnSe crystals in which the activators were doped with tellurium and oxygen. ZnSe and CsI crystals were mounted on a S3590-08 HAMAMATSU PIN photodiode and an R3479 HAMAMATSU PMT. Teflon tape as a reflector for the PIN photodiode and PMT. Gamma-ray spectrum measurements were performed by using 241Am, 57Co, 133Ba and 137Cs radio isotopes. We have compared the measured spectra of ZnSe and CsI under the same conditions.