Search

Elemental analysis is a fundamental method for determining the carbon, hydrogen, nitrogen, sulphur, and oxygen (CHNSO) contents in organic materials. Automated conventional elemental analysers are commonly used for CHNSO determinations, but they face challenges when analysing volatile organic liquids due to sample losses. This present study explores the combination of gas chromatography–mass spectrometry (GC/MS) and gas chromatography–flame ionisation detection (GC/FID) as a more accurate alternative method for elemental analysis of such liquids. Six different liquid samples containing various organic compounds have been analysed using both a conventional elemental analyser (Method 1) and the combined GC/MS–GC/FID method (Method 2). The results showed that Method 1 gave results with significant errors for carbon (by more than ±10 wt%) and oxygen (by up to ±30 wt%) contents due to volatile losses leading to inaccurate "oxygen-by-difference" determinations. In contrast, Method 2 gave more accurate and consistently representative elemental data in a set of simulated samples when compared to theoretical elemental data. This work proposes the use of the GC/FID method as a reliable alternative for CHNSO analysis of volatile organic liquids and suggests that employing the GC/FID technique can mitigate the common errors associated with conventional CHNSO analysis of such samples. However, successfully using Method 2 would depend on the skills and experience of users in qualitative and quantitative organic chemical analyses by gas chromatography. [ABSTRACT FROM AUTHOR]

Automated mineralogy is a software addition usually seen on scanning electron microscopes designed to provide rapid insight into sample chemistry and texture in routine petrology workflows. The specific purpose of automated mineralogy is to provide mineral classifications to uniquely identified phases typically using energy dispersive spectroscopy, thus removing laborious and time‐consuming human input for routine tasks. These mineral classifications can then be applied to image data to quantify which mineral is associated with any particular texture. Automated mineralogy systems were primarily designed to generate quantitative textural analysis of particle samples to the mining industry and have remained a critical technique in this setting for the last several decades. Automated mineralogy has become more widely used in academia, and this has changed the focus of the technique, applying it to a broader range of workflows and applications. Here we show petrology examples focussing where combined geochemical and textural analysis are widely used. Critically, the use of quantitative geochemical data means that mineral classifications are based on their quantitatively measured chemistry. By making both the chemical and textural analysis quantitative, automated mineralogy can become highly flexible and provide a unique system for petrologists in both industry and academia. [ABSTRACT FROM AUTHOR]

The impact of major sudden stratospheric warming (SSW) events and early final stratospheric warming (FSW) events on ozone variations in the middle atmosphere in the Arctic is investigated by performing microwave radiometer measurements above Ny-Ålesund, Svalbard (79° N, 12° E), with GROMOS-C (GRound-based Ozone MOnitoring System for Campaigns). The retrieved daily ozone profiles during SSW and FSW events in the stratosphere and lower mesosphere at 20–70 km from microwave observations are cross-compared to MERRA-2 (Modern-Era Retrospective Analysis for Research and Applications, version 2) and MLS (Microwave Limb Sounder). The vertically resolved structures of polar ozone anomalies relative to the climatologies derived from GROMOS-C, MERRA-2, and MLS shed light on the consistent pattern in the evolution of ozone anomalies during both types of events. For SSW events, ozone anomalies are positive at all altitudes within 30 d after onset, followed by negative anomalies descending in the middle stratosphere. However, positive anomalies in the middle and lower stratosphere and negative anomalies in the upper stratosphere at onset are followed by negative anomalies in the middle stratosphere and positive anomalies in the upper stratosphere during FSW events. Here, we compare results by leveraging the ozone continuity equation with meteorological fields from MERRA-2 and directly using MERRA-2 ozone tendency products to quantify the impact of dynamical and chemical processes on ozone anomalies during SSW and FSW events. We document the underlying dynamical and chemical mechanisms that are responsible for the observed ozone anomalies in the entire life cycle of SSW and FSW events. Polar ozone anomalies in the lower and middle stratosphere undergo a rapid and long-lasting increase of more than 1 ppmv close to SSW onset, which is attributed to the dynamical processes of the horizontal eddy effect and vertical advection. The pattern of ozone anomalies for FSW events is associated with the combined effects of dynamical and chemical terms, which reflect the photochemical processes counteracted partially by positive horizontal eddy transport, in particular in the middle stratosphere. In addition, we find that the variability in polar total column ozone (TCO) is associated with horizontal eddy transport and vertical advection of ozone in the lower stratosphere. This study enhances our understanding of the mechanisms that control changes in polar ozone during the life cycle of SSW and FSW events, providing a new aspect of quantitative analysis of dynamical and chemical fields. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the influence of reactive oxygen species (i.e., neutral O atom and O 2 + ion) on deposition rates and film thickness uniformity in tetraethoxysilane (TEOS) plasma, utilizing a combination of plasma-fluid dynamic and quantum chemical (QC) simulations. The plasma simulations employed an improved model based on a previous study [H. Li et al., Jpn. J. Appl. Phys. 58, SEED06 (2019)], specifically tailored for a TEOS/O2/Ar/He gas mixture. In the QC simulations, both flat and step silicon oxide (SiO2) surfaces were employed to investigate the adsorption behavior of SiO molecules, the predominant silicon-containing species in TEOS plasma. These simulations also enabled the examination of the rates of SiO molecule adsorption on SiO2 surfaces, facilitating a direct comparison with the sticking coefficients utilized in the plasma simulation. The results of QC simulations revealed that SiO molecules exhibited a higher energetic preference for adsorption on step surfaces than on flat surfaces, resulting in the formation of new SiOH surface sites. Meanwhile, the plasma simulations demonstrated a strong correlation between the deposition rate and film thickness uniformity and the generation of oxygen species, specifically O atoms and O 2 + ions, as well as their respective fluxes. This relationship takes precedence over the influence of TEOS or its fragments colliding with the surface. Notably, higher plasma source frequencies were found to enhance the production of atomic O, which contributed significantly to achieving higher deposition rates. [ABSTRACT FROM AUTHOR]

A group of hypothetical compounds Mg2NA (A = F, Cl, Br, I) with the antichalcopyrite structure is considered. Optimized geometries, structures and compositions of the band spectra at all high-symmetry points of the first Brillouin zone are determined for all compounds. A qualitative and quantitative analysis of chemical bonds is performed using electron density distributions, the electron localization function, and Wannier functions. [ABSTRACT FROM AUTHOR]

Copyright of China Fiber Inspection is the property of China Fiber Inspection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Fiber Inspection is the property of China Fiber Inspection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Yinhua Pinggan Granule (YPG) is an approved compounded traditional Chinese medicine (TCM) prescription for the treatment of cold, cough, viral pneumonia, and related diseases. Due to its complicated chemical composition, the material basis of YPG has not been systematically investigated. In this study, an analytical method based on high-performance liquid chromatography (HPLC) coupled with Q-Exactive mass spectrometry was established. Together with the help of a self-built compound database and Compound Discoverer software 3.1, the chemical components in YPG were tentatively identified. Subsequently, six main components in YPG were quantitatively characterized with a high-performance liquid chromatography–diode array detector (HPLC-DAD) method. As a result, 380 components were annotated, including 19 alkaloids, 8 organic acids, 36 phenolic acids, 27 other phenols, 114 flavonoids, 75 flavonoid glycoside, 72 terpenes, 11 anthraquinones, and 18 other compounds. Six main components, namely, chlorogenic acid, puerarin, 3′-methoxypuerarin, polydatin, glycyrrhizic acid, and emodin, were quantified simultaneously. The calibration curves of all six analytes showed good linearity (R2 > 0.9990) within the test ranges. The precision, repeatability, stability, and recovery values were all in acceptable ranges. In addition, the total phenol content and DPPH scavenging activity of YPG were also determined. The systematic elucidation of the chemical components in YPG in this study may provide clear chemical information for the quality control and pharmacological research of YPG and related TCM compounded prescriptions. [ABSTRACT FROM AUTHOR]

Multi‐principal element alloys (MPEAs) are gaining interest in corrosion and electrocatalysis research due to their electrochemical stability across a broad pH range and the design flexibility they offer. Using the equimolar CrCoNi alloy, we observe significant metal dissolution in a corrosive electrolyte (0.1 M NaCl, pH 2) concurrently with the oxygen evolution reaction (OER) in the transpassive region, despite the absence of hysteresis in polarization curves or other obvious corrosion indicators. We present a characterization scheme to delineate the contribution of OER and alloy dissolution, using scanning electrochemical microscopy (SECM) for OER‐onset detection, and quantitative chemical analysis with inductively coupled‐mass spectrometry (ICP‐MS) and ultraviolet visible light (UV/Vis) spectrometry to elucidate metal dissolution processes. In situ electrochemical atomic force microscopy (EC‐AFM) revealed that the transpassive metal dissolution on CrCoNi is dominated by intergranular corrosion. These results have significant implications for the stability of MPEAs in corrosion systems, emphasizing the necessity of analytically determining metal ions released from MPEA electrodes into the electrolyte when evaluating Faradaic efficiencies of OER catalysts. The release of transition metal ions not only reduces the Faradaic efficiency of electrolyzers but may also cause poisoning and degradation of membranes in electrochemical reactors. [ABSTRACT FROM AUTHOR]

The solubility of Eu(III) was investigated under undersaturated conditions in acidic, dilute to concentrated MgSO4 and Na2SO4 solutions at T = (22 ± 2) ℃. After attaining equilibrium conditions, solid phases were characterized by a multi-method approach, including X-ray diffraction (XRD), Raman and infrared (IR) spectroscopy, quantitative chemical analysis (ICP-OES) and thermogravimetric analysis (TG-DTA). A total of 45 solubility samples were investigated for the systems Eu2(SO4)3-MgSO4-H2O (19 samples) and Eu2(SO4)3-Na2SO4-H2O (26 samples). Eu2(SO4)3.8H2O(cr) was found to control the solubility of Eu(III) in all investigated MgSO4 solutions, as well as in dilute Na2SO4 systems. The transformation of Eu2(SO4)3. 8H2O(cr) into the double salt Na2Eu2(SO4)4.2H2O(cr) was observed at mNa2SO4 > 0.01 mol kg-1. The latter phase is characterized by significantly lower solubility. Based on these experimental solubility measurements, thermodynamic and activity models were proposed based on the Pitzer equations considering the full dissociation of the Eu(III) species in MgSO4 and Na2SO4 aqueous solutions, i.e. deliberately excluding Eu(III)-sulfate complex formation. A combination of the geochemical calculation code PhreeSCALE and the parameter estimation code PEST was used to determine the values of solubility products ðK°s;0Þ and binary and ternary specific interaction parameters (β(0)ij, β(1)ij, Cϕij, θik, Ψijk). [ABSTRACT FROM AUTHOR]

The layer-by-layer analysis of the variation dynamics of chemical parameters of snow at one of the observation sites (at the village of Yaksha) in the Pechora–Ilych state biosphere reserve in the winter of 2019–2020 has shown that the chemical composition of atmospheric precipitation is affected dominantly by long-range material transport. Features of the atmospheric circulation and the regions from which air masses are transferred control the saturation of the precipitation with certain chemical components. The calculation of the trajectories of reverse transport of air masses allowed us to identify regions where the air masses can be formed that come to the study area and carry material that potentially affects the chemical composition of the precipitation. The calculation of trajectories is demonstrated to make it possible to identify source regions of pollutants entering the atmosphere. This method of studying the chemical composition of snow is generally very informative and enables better understanding its formation factors. [ABSTRACT FROM AUTHOR]

Yanyangke mixture (YM) is composed of 12 kinds of traditional Chinese medicine (TCM) used for the treatment of patients with cough, dry throat and other diseases caused by acute or chronic pharyngitis or patients with difficulty in expectoration. With the wide application of YM in clinical practice, its quality control has attracted huge attention. Based on the multi-component characteristics of Chinese herbal medicines, it is pertinent to establish a quality evaluation system. A new idea is to adopt gas chromatography–mass spectrometry (GC–MS) chemical composition identification, GC–MS fingerprint, and GC content determination as a potential quality control index of the volatile oil in YM. In this study, the volatile oil of YM was extracted by steam distillation, and the chemical components of the volatile oil were analyzed by GC–MS, and 43 chemical components were identified. The fingerprint of the volatile oil from YM was established and the similarity evaluation was performed. Combined with chemometric methods, such as cluster analysis, principal component analysis and partial least squares analysis, the chemical composition differences of the volatile oil from different batches of YM were compared and the symbolic components affecting the quality of the volatile oil from different batches of YM were excavated. Finally, three components were selected as the potential active component markers of YM and the GC content determination method of these three components was established. A rapid, reasonable, and effective quality evaluation and control method of YM volatile oil was established, which provided a reference for further development and research on YM, as well as a new idea for research on other TCM prescriptions. [ABSTRACT FROM AUTHOR]

The way of thinking of mathematicians and chemists in their respective disciplines seems to have very different levels of abstractions. While the firsts are involved in the most abstract of all sciences, the seconds are engaged in a practical, mainly experimental discipline. Therefore, it is surprising that many luminaries of the mathematics universe have studied chemistry as their main subject. Others have started studying chemistry before swapping to mathematics or have declared some admiration and even love for this discipline. Here I reveal some of these mathematicians who were involved in chemistry from a biographical perspective. Then, I analyze what these remarkable mathematicians and statisticians could have learned while studying chemical subjects. I found analogies between code-breaking and molecular structure elucidation, inspiration for statistics in quantitative analytical chemistry, and on the role of topology in the study of some organic molecules. I also analyze some parallelisms between the way of thinking of organic chemists and mathematicians in terms of the use of backward analysis, search for patterns, and use of pictures in their respective researches. [ABSTRACT FROM AUTHOR]

Hydroxalkanoate polymers, or polyhydroxyalkanoates (PHAs) are a diverse group of prokaryotic carbon and energy storage reserves. Since, PHAs have many of the same material characteristics as traditional plastics, they have been the subject of much interest as biodegradable alternatives to traditional fossil fuel based plastic polymers. Lately, much attention has been focused on establishing methods for the cost-effective manufacturing of PHAs. The isolation, qualitative and quantitative analysis and chemical characterisation of polyhydroxyalkanoates (PHAs) play a crucial role in the establishment of any kind of procedure. Various methodologies are required to initially identify potent microorganisms capable of synthesising polyhydroxyalkanoates (PHA), subsequently to ascertain unique building units of PHA polymer and last, to comprehend the structural and conformational chemistry of PHA at the intramolecular scale. This work aims to consolidate the existing methodologies for the identification, quantitative measurement and characterization of polyhydroxyalkanoates (PHAs), while also examining their respective merits and drawbacks. [ABSTRACT FROM AUTHOR]

The impact of major sudden stratospheric warming (SSW) events and early final stratospheric warming (FSW) events on ozone variations in the middle atmosphere in the Arctic is investigated by performing microwave radiometer measurements above Ny-Ålesund, Svalbard (79° N, 12° E) with GROMOS-C. The retrieved daily ozone profiles during SSW and FSW events in the stratosphere and lower mesosphere at 20–70 km from microwave observations are cross-compared to MERRA-2 and MLS. The vertically resolved structure of polar ozone anomalies relative to the climatologies derived from GROMOS-C, MERRA-2, and MLS shed light on the consistent pattern in the evolution of ozone anomalies during both types of events. For SSW events, ozone anomalies are positive throughout all altitudes within 30 days after the onset, followed by negative anomalies descending downward in the middle stratosphere. However, positive anomalies in the middle and lower stratosphere and negative in the upper stratosphere at onset are followed by negative anomalies with descending in the middle stratosphere and positive anomalies in the upper stratosphere during FSW events. We document the underlying dynamical and chemical mechanisms that are responsible for the observed ozone anomalies in the entire life cycle of SSW and FSW events. Polar ozone anomalies in the lower and middle stratosphere undergo a rapid and long-lasting increase of more than 1 ppmv close to SSW onset, which is attributed to the dynamical processes of the horizontal eddy effect and vertical advection. This response pattern for FSW events is associated with the combined effects of dynamical and chemical terms, which reflect the photochemical processes counteracted partially by positive horizontal eddy transport, in particular in the middle stratosphere. Here, we contrast results from MERRA-2 reanalysis and chemistry-climate models to quantify the impact of dynamical and chemical processes on ozone anomalies during SSW and FSW events. In addition, we find that the variability in polar total column ozone (TCO) is associated with horizontal eddy transport and vertical advection of ozone in the lower stratosphere. This study enhances our understanding of the mechanisms that control changes in polar ozone during the life cycle of SSW and FSW events, providing a new aspect to quantitative analysis of dynamical and chemical fields. [ABSTRACT FROM AUTHOR]

In order to characterize red wine polymers with regard to their binding properties to aroma compounds (odorants), a qualitative and quantitative analysis of chemical degradation products after different chemical treatments (thiolytic, acidic, and alkaline depolymerization) of high -molecular-weight (HMW) fractions of red wine was performed. Using 1H NMR, LC-ToF-MS, LC-MS/MS, and HPIC revealed key structural features such as carbohydrates, organic acids, phenolic compounds, anthocyanins, anthocyanidins, amino acids, and flavan-3-ols responsible for odorant-polymer interactions. Further, NMR-based interaction studies of the selected aroma compounds 3-methylbutanol, cis-whisky lactone, 3-methylbutanoic acid, and 3-isobutyl-2-methoxypyrazine with HMW polymers after chemical treatment demonstrated a reduced interaction affinity of the polymer compared to the native HMW fractions, and further, the importance of aromatic compounds such as flavan-3-ols for the formation of odorant polymer interactions. In addition, these observations could be verified by human sensory experiments. For the first time, the combination of a compositional analysis of red wine polymers and NMR-based interaction studies with chemically treated HMW fractions enabled the direct analysis of the correlation of the polymer's structure and its interaction affinity with key odorants in red wine. [ABSTRACT FROM AUTHOR]

Inductively coupled plasma atomic emission spectrometry (ICP-AES), two-jet arc plasma atomic emission spectrometry (TJP-AES), and inductively coupled plasma mass spectrometry (ICP-MS) are among the most informative methods for the quantitative chemical analysis (QCA) of high-purity substances and functional materials, both in the set of analytes and in their limits of detection (LODs). At the same time, the analytical capabilities of QCA methods in their standard version are not always sufficient for determining analytes at a level of 10−9−10−7% (ppb and ppt). The use of combined (including the stage of the preconcentration of trace elements) QCA procedures and alternative methods of sample introduction into ICP, which increase the efficiency of using trace element concentrates, makes it possible to reduce the instrumental LODs for analytes by 1–2 orders of magnitude and expand the capabilities of the methods. The presented mini-review examines the results of using the ICP-AES, TJP-AES, and ICP-MS methods for the analysis of high-purity Ge, Cd, Te, Zn with the preconcentration of trace elements by distilling off the matrix of the sample, the use of electrothermal vaporization for introducing samples into plasma sources, and also the use of laser ablation ICP-MS for the analysis of trace element concentrates using the so-called "thin layer method". [ABSTRACT FROM AUTHOR]

The paper offers a brief overview of the modern procedures for determining the chemical composition of copper alloys along with the applied methods of analytical control. It has been shown that to obtain reliable and comparable results of measuring the mass fractions of copper alloys elements within wide ranges of values, the most suitable procedures are based on the X‑ray fluorescence method, implemented using portable X‑ray fluorescence spectrometers. In order to select the optimal values of the influencing quantities when determining the chemical composition of copper alloys, a robust parameter design of a quantitative chemical analysis procedure was carried out using X‑50 Mobile X‑ray fluorescence spectrometer. The use of robust parameter design as opposed to conducting a full factorial experiment when developing a measurement procedure makes it possible to optimize the measurement conditions and obtain results of the required accuracy with a limited number of experiments and a maximum number of controlled factors. An example of drawing up an experimental plan for the parameter design of such procedure is provided, and a statistical analysis of the measurement results is carried out. The authors have analyzed and selected the optimal measurement conditions (influencing quantities), which ensure the minimum error of the results of measuring the mass fraction of elements. By selecting the optimal values of the influencing quantities based on the results of robust parameter design of the quantitative chemical analysis procedure, it became possible to increase the accuracy of determining the chemical composition of copper alloys and, hence, improve the reliability of the product quality control results at a relatively low cost. Such approach can be recommended for use by analytical laboratories developing procedures of quantitative chemical analysis for metallurgical enterprises. [ABSTRACT FROM AUTHOR]

Introduction: The designer benzodiazepine (DBZD) market continues to expand whilst evading regulatory controls. The widespread adoption of social media by pro-drug use communities encourages positive discussions around DBZD use/misuse, driving demand. This research addresses the evolution of three popular DBZDs, etizolam (E), flubromazepam (F), and pyrazolam (P), available on the drug market for over a decade, comparing the quantitative chemical analyses of tablet samples, purchased from the internet prior to the implementation of the Psychoactive Substances Act UK 2016, with the thematic netnographic analyses of social media content. Method: Drug samples were purchased from the internet in early 2016. The characterisation of all drug batches were performed using UHPLC-MS and supported with 1H NMR. In addition, netnographic studies across the platforms X (formerly Twitter) and Reddit, between 2016–2023, were conducted. The latter was supported by both manual and artificial intelligence (AI)-driven thematic analyses, using numerous.ai and ChatGPT, of social media threads and discussions. Results: UHPLC-MS confirmed the expected drug in every sample, showing remarkable inter/intra batch variability across all batches (E = 13.8 ± 0.6 to 24.7 ± 0.9 mg; F = 4.0 ± 0.2 to 23.5 ± 0.8 mg; P = 5.2 ± 0.2 to 11.5 ± 0.4 mg). 1H NMR could not confirm etizolam as a lone compound in any etizolam batch. Thematic analyses showed etizolam dominated social media discussions (59% of all posts), with 24.2% of posts involving sale/purchase and 17.8% detailing new administration trends/poly-drug use scenarios. Artificial intelligence confirmed three of the top five trends identified manually. Conclusions: Purity variability identified across all tested samples emphasises the increased potential health risks associated with DBZD consumption. We propose the global DBZD market is exacerbated by surface web social media discussions, recorded across X and Reddit. Despite the appearance of newer analogues, these three DBZDs remain prevalent and popularised. Reporting themes on harm/effects and new developments in poly-drug use trends, demand for DBZDs continues to grow, despite their potent nature and potential risk to life. It is proposed that greater controls and constant live monitoring of social media user content is warranted to drive active regulation strategies and targeted, effective, harm reduction strategies. [ABSTRACT FROM AUTHOR]

A molecule's antibacterial and antiviral action is exclusively linked to substances that selectively eradicate bacteria and viruses or inhibit their growth without significantly damaging adjacent tissues. The purpose of this research is to evaluate quantitative and qualitative phytochemical analysis and the antibacterial effects of Manilkara zapota fruit extract on some Gram-positive (Staphylococcus aureus, Enterococcus faecalis, Micrococcus luteus, Bacillus cereus, and Listeria monocytogenes) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae) bacteria in laboratory conditions. Qualitative chemical screening was used to identify different classes of active chemical compounds, and quantitative analysis of the chemical composition of the plant was used to measure the contents of flavonoid, total phenol, anthocyanin, and antioxidant activity. Antibacterial effects of Manilkara zapota ethanol extract were determined by disk diffusion methods, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). Qualitative chemical screening revealed the presence of flavonoids, tannins, quinones, terpenoids, and glycosides while the presence of saponins was not observed. The bacterial inhibition zones against Listeria monocytogenes, Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus, Micrococcus luteus, Escherichia coli, Klebsiella pneumoniae, and Bacillus cereus are 15.44 ± 0.33, 12.23 ± 0.11, 8.85 ± 0.2, 14.22 ± 0.33, 15 ± 0.44, 9.33 ± 0.13, 10.33 ± 0.36 and 14.55 ± 0.45 mm, respectively. MIC and MBC of the extract in Gram-positive bacteria were 25 and 50, and in Gram-negative bacteria were 50 and 100 mg/ml, respectively. The findings imply that Manilkara zapota extract includes a good amount of plant compounds and can be a significant source for a variety of uses, including antibacterial. [ABSTRACT FROM AUTHOR]

The specific objective of this study was to investigate the effect of reactive ethylene terpolymer (RET) modification on bitumen properties at the nano and macro scales, as well as on porous asphalt (PA) mix properties. Measurements using the dynamic shear rheometer (DSR) and the bending beam rheometer (BBR) showed that RET modification of bitumen significantly improved the high-temperature properties, while intermediate- and low-temperature properties were similar to the base bitumen. The linear amplitude sweep (LAS) test conducted using the DSR showed that RET modification improved fatigue resistance. Consequently, chemical analysis and PeakForce™ Quantitative Nano-Mechanical™ (PF-QNM) atomic force microscopy (AFM) imaging were used to evaluate the microstructure and nanomechanical properties of the polymer modified bitumen (PMB) and the base bitumen before and after long-term ageing. The chemical analysis provided useful insights that complemented and helped to explain the AFM and rheology tests. The AFM results supported the LAS test findings in showing that RET modification improved the resistance of aged bitumens to cracking. The results of testing the PA mix showed significant improvements in moisture damage and ravelling resistance due to RET modification. [ABSTRACT FROM AUTHOR]

Female chemical signals are crucial for sexual communication in spiders and convey detailed information about females' mating status or age. However, evidence for chemical communication in spiders is largely behavioral. Only a few spider pheromones are known and quantitative chemical analyses of individual spiders are especially scarce. In the European wasp spider, Argiope bruennichi (Scopoli, 1772), females emit the volatile trimethyl methylcitrate, which attracts males from a distance. A recent study on the role of this pheromone in close-range male mate choice revealed that older virgin females approaching oviposition produce higher amounts of pheromone than younger ones, thereby increasing their attractiveness to males, and stop pheromone signaling shortly after copulation. Here we provide more detailed analyses of temporal dynamics in pheromone production in both virgin and mated female A. bruennichi. Our results corroborate previous observations indicating that male mating behavior in this species is guided by variation in female signaling effort. [ABSTRACT FROM AUTHOR]

Research on the additive manufacturing of metals often neglects any characterization of the composition of final parts, erroneously assuming a compositional homogeneity that matches the feedstock material. Here, the composition of electron-beam-melted Ti-6Al-4V produced through three distinct scanning strategies (linear raster and two point melting strategies, random fill and Dehoff fill) is characterized both locally and globally through energy-dispersive spectroscopy and quantitative chemical analysis. As a result of the different scanning strategies used, differing levels of preferential vaporization occur across the various parts, leading to distinct final compositions, with extremes of ~5.8 wt.% Al and ~4.8 wt.% Al. In addition, energy-dispersive spectroscopy composition maps reveal specific features in both the XY and XZ planes (with Z being the build direction) as a result of local inhomogeneous preferential vaporization. The subsequent change in composition significantly modifies the materials' state of parts, wherein parts and local regions with higher aluminum contents lead to higher hardness levels (with a ~50 HV difference) and elastic property values and vice versa. While varying scan strategies and scan parameters are known to modify the microstructure and properties of a part, the effect on composition cannot, and should not, be neglected. [ABSTRACT FROM AUTHOR]

Insects avoid predation in various ways, and some use multiple ways to avoid predation. However, the effects of comprehensive avoidance methods and the differences in avoidance methods among different life stages of insects have not been sufficiently discussed. The big head stick insect Megacrania tsudai uses background matching as its primary defense and chemical defense as its secondary defense. The aims of this study were to identify and isolate the chemical components of M. tsudai using repeatable methods, determine the amount of the main chemical compound, and reveal the effect of the main chemical compound on its predators. We established a repeatable gas chromatography-mass spectrometry (GC–MS) method to identify the chemical compounds of these secretions, and identified actinidine as the main compound. Actinidine was identified by nuclear magnetic resonance (NMR), and the amount of actinidine in each instar was calculated by constructing a calibration curve using pure actinidine. Mass ratios did not drastically change among instars. Furthermore, experiments involving dropping an aqueous solution of actinidine demonstrated removal behavior in geckos, frogs, and spiders. These results indicated that M. tsudai conducts secondary defenses using defensive secretions consisting mainly of actinidine. [ABSTRACT FROM AUTHOR]

In order to find out the mineralization of tin and copper polymetallic ore in Gaofengshan ore section of the Gejiu mining area in Yunnan, and whether the main elements Sn, Cu, Pb, Zn, W, etc. in the ore body can be recycled. In this paper, the typical ore controlling zone of the Gaofengshan ore block, the granite body depression zone, is sampled and the ore body exposed by the pit drilling is made into thin slices, and the detailed mineral and result observation is carried out under the microscope, to find out the mineral composition, symbiotic relationship, generation sequence, and occurrence form, and at the same time, the quantitative analysis of the ore chemical element properties of all samples is carried out. The analysis elements and composition mainly include: Sn, Cu, Pb, Zn, and WO3, Then the R type cluster analysis was performed by SPSS statistical software. The research results indicate that the tin copper polymetallic ore in the Gaofengshan ore block is the result of multi period and multi stage hydro thermal co location superposition mineralization, and the elements such as Sn, Cu, Pb, Zn, and W are mainly produced in the form of independent minerals, which are easy to dissociate, and are conducive to beneficiation and recovery. It provides basic geological data for the comprehensive evaluation work, the development of the ore mining plan, and the development of a comprehensive recovery and beneficiation process in the future production and exploration process. [ABSTRACT FROM AUTHOR]

Recent studies have established that the anti-Stokes Raman signal from plasmonic metal nanostructures can be used to determine the two separate temperatures that characterize carriers inside the metal—the temperature of photoexcited "hot carriers" and carriers that are thermalized with the metal lattice. However, the related signal in the Stokes spectral region has historically impeded surface enhanced Raman spectroscopy, as the vibrational peaks of adsorbed molecules are always accompanied by the broad background of the metal substrate. The fundamental source of the metal signal, and hence its contribution to the spectrum, has been unclear. Here, we outline a unified theoretical model that describes both the temperature-dependent behavior and the broad spectral distribution. We suggest that the majority of the Raman signal is from inelastic scattering directly with carriers in a non-thermal energy distribution that have been excited via damping of surface plasmon. In addition, a significant spectral component (∼1%) is due to a sub-population of hot carriers with an energy distribution that is well approximated by an elevated temperature distribution, about 2000 K greater than the lattice temperature of the metal. We have performed temperature- and power-dependent Raman experiments to show how a simple fitting procedure reveals the plasmon dephasing time as well as the temperatures of the hot carriers and the metal lattice, in order to correlate these parameters with the quantitative Raman analysis of chemical species adsorbed on the metal surface. [ABSTRACT FROM AUTHOR]

New flowing afterglow/Langmuir probe investigations of electronic attachment to SF6 are described. Thermal attachment rate constants are found to increase from 1.5 × 10−7 cm3 s−1 at 200 K to 2.3 × 10−7 cm3 s−1 at 300 K. Attachment rate constants over the range of 200–700 K (from the present work and the literature), together with earlier measurements of attachment cross sections, are analyzed with respect to electronic and nuclear contributions. The latter suggest that only a small nuclear barrier (of the order of 20 meV) on the way from SF6 to SF6− has to be overcome. The analysis shows that not only s-waves but also higher partial waves have to be taken into account. Likewise, finite-size effects of the neutral target contribute in a non-negligible manner. [ABSTRACT FROM AUTHOR]

The article discusses the lipophilicity of drugs, particularly local anesthetics, and its association with lipid emulsion resuscitation. It mentions a novel approach called the DiSC block, which is a potentially safer and simpler anterior approach for the suprascapular nerve (SSN) block. The article also compares the sub-omohyoid SSN block with the DiSC block, highlighting the advantages and risks of each approach. The conclusion suggests that the diagonal suprascapular block is a simple, more selective, and safer anterior SSN block. [Extracted from the article]

Gandouling tablets are used in a clinical agent for the treatment of hepatocellular degeneration; however, their chemical constituents have not been elucidated. Here, we screened and identified the chemical constituents of Gandouling tablets using ultra‐high‐performance liquid chromatography (UHPLC)‐quadrupole time of flight/mass spectrometry. A method for the quality evaluation of Gandouling tablets was developed by combining the UHPLC fingerprints and the simultaneous quantitative analysis of multiple active ingredients. For fingerprint analysis, 20 shared peaks were identified to assess the similarities among the 10 batches of Gandouling tablets and the similarity was >0.9. The levels of nine representative active ingredients were simultaneously determined to ensure consistency in quality. A total of 99 chemical components were identified, including 18 alkaloids, 20 anthraquinones, 13 flavonoids, 11 phenolic acids, 9 polyphenols, 7 phenanthrenes, 5 sesquiterpenes, 3 curcuminoids, 2 lignans, 2 isoflavones, 2 dianthranones, and 7 other components. The retention times, molecular formulae, and secondary fragmentation information of these compounds were analyzed, and the cleavage pathways and characteristic fragments of some of the representative compounds were elucidated. This systematic analysis used to identify the chemical components of Gandouling tablets lays the foundation for its further quality control and research on their pharmacodynamic substances. [ABSTRACT FROM AUTHOR]

The Yuquan capsules is a commonly used traditional Chinese Patent Medicine used for the treatment of diabetes mellitus. In this study, a high‐throughput analytical method for identifying the chemical composition of Yuquan capsules was established for the first time by using ultra‐performance liquid chromatography–quadrupole time of flight mass spectrometry. The data obtained were subjected to fragment analysis and this was combined with UNIFI processing of natural products. One‐hundred sixteen compounds were characterized from Yuquan capsules. Twelve of the bioactive compounds were quantitatively analyzed by ultra‐performance liquid chromatography‐tandem triple quadrupole mass spectrometry. This study was undertaken to obtain a comprehensive chemical profile analysis as well as to evaluate the overall quality of Yuquan capsules. The results will provide a reference for the quality evaluation of different Yuquan preparations. In addition, the data will enable basic pharmacodynamic research into these extensively used capsules. [ABSTRACT FROM AUTHOR]

It is noticed that the conventional interpretation of systematic errors (or, what is the same, the list of varieties of systematic errors) generally reflects the actual situation, which does not exclude some refilling and specification with the appearance of new types of measurements and the sophistication of the existing ones. These additions should not mean the abolition of the general metrological, time-tested classification. In recent decades, trends have appeared aimed at replacing the meanings of terms and definitions with those uncharacteristic of them, or at introducing terms that have no real meaning at all into metrological practice. This, in turn, led to the emergence of erroneous concepts ensuring the accuracy of the results of quantitative chemical analysis and to the creation of far from perfect regulatory documents, which, among other reasons, was due to an uncritical attitude to international standards. Such concepts bring inaccuracies and erroneous recommendations into monographs and textbooks containing sections related to the metrological aspects of chemical analysis. [ABSTRACT FROM AUTHOR]

A high sulfur content is one of the challenges in the processing of refractory bauxites in China. The high carbon content of bauxite makes it more difficult to deal with. Desulfurization and decarbonization are the critical issues in the efficient exploitation of high-sulfur bauxite resources. An experimental study on the removal of sulfur and carbon in high-sulfur bauxite is proposed. The sulfur and carbon phases in high-sulfur bauxite were studied via X-ray diffraction and chemistry quantitative analyses. The results show that the sulfur phases in the high-sulfur bauxite mainly exist in the form of sulfide sulfur (pyrite), and the carbon phases in the sample mainly exist in the form of elementary substance carbon. The morphological features of pyrite in the high-sulfur bauxite were analyzed using a microscopic analysis and a scanning electron microscope (SEM). The pyrite exists in minerals in the forms of euhedral, semi-euhedral and other crystalline structures, with a particle size varying from several hundred microns to only a few microns. The raw ore, with a sulfur content of 4.78%, a sulfide sulfur content of 4.20%, a carbon content of 3.10% and an elementary substance carbon content of 2.46% goes through the "one roughing, one cleaning, two scavenging" process after a pre-decarburization, obtaining the total desulfurization recovery of 96.20% with a desulfurization tailing sulfur content of 0.38%, a carbon content of 0.27% and an alumina content of 71.85%, respectively. This work provides technical support for the efficient utilization of high-sulfur and high-carbon bauxite. [ABSTRACT FROM AUTHOR]

Introduction: Zhixue Zhentong capsules (ZXZTCs) are a Tibetan medicine preparation solely composed of Lamiophlomis rotata (Benth.) Kudo. L. rotata is the only species of the genus Laniophlomis (family Lamiaceae) that has medicinal constituents derived from the grass or root and rhizome. L. rotata is one of the most extensively used folk medicines by Tibetan, Mongolian, Naxi, and other ethnic groups in China and has been listed as a first-class endangered Tibetan medicine. The biological effects of the plant include hemostasis, analgesia, and the removal of blood stasis and swelling. Purpose: This study aimed to profile the overall metabolites of ZXZTCs and those entering the blood. Moreover, the contents of six metabolites were measured and the hemostatic, analgesic, and anti-inflammatory effects of ZXZTCs were explored. Methods: Ultra-performance liquid chromatography-tandem quadrupole timeof-flight high-resolution mass spectrometry (UPLC-Q-TOF-MS) was employed for qualitative analysis of the metabolites of ZXZTCs and those entering the blood. Six metabolites of ZXZTCs were quantitatively determined via high-performance liquid chromatography The hemostatic, analgesic, and anti-inflammatory effects of ZXZTCs were evaluated in various animal models. Results: A total of 36 metabolites of ZXZTCs were identified, including 13 iridoid glycosides, 9 flavonoids, 9 phenylethanol glycosides, 4 phenylpropanoids, and 1 other metabolite. Overall, 11 metabolites of ZXZTCs entered the blood of normal rats. Quantitative analysis of the six main metabolites, shanzhiside methyl ester, chlorogenic acid, 8-O-acetyl shanzhiside methyl ester, forsythin B, luteoloside, and verbascoside, was extensively performed. ZXZTCs exerted hemostatic effects by reducing platelet aggregation and thrombosis and shortening bleeding time. Additionally, ZXZTCs clearly had an analgesic effect, as observed through the prolongation of the latency of writhing, reduction in writhing, and increase in the pain threshold of experimental rats. Furthermore, significant anti-inflammatory effects of ZXZTCs were observed, including a reduction in capillary permeability, the inhibition of foot swelling, and a reduction in the proliferation of granulation tissue. Conclusion: Speculative identification of the overall metabolites of ZXZTCs and those entering the blood can provide a foundation for determining its biologically active constituents. The established method is simple and reproducible and can help improve the quality control level of ZXZTCs as a medicinal product. Evaluating the hemostatic, analgesic, and anti-inflammatory activities of ZXZTCs can help reveal its mechanism. [ABSTRACT FROM AUTHOR]

Rationale: Mass spectrometry has evolved into a highly powerful tool for qualitative and quantitative chemical analyses. However, the identification of trace amounts of previously unknown structures in complex chemical matrix environments remains challenging. The rapid emergence of new synthetic cannabinoid substances is a typical example of this. Existing laboratory techniques are mostly based on methods used for lists of known illegal compounds. This situation poses a challenge to traditional data analysis and the risk of missing the compounds. Therefore, we propose to develop and validate a statistical model to classify newly emerging synthetic cannabinoid substances into a structural class or subclass. Methods: We obtained 70 electrospray ionization spectra of indole/indazole synthetic cannabinoids from both the actual standard analysis and the SWGDRUG mass spectral library (version 3.10). Each sample consisted of 330 m/z variables and corresponding relative intensities. We first cleared the variables with a variance below 0.1. Principal component analysis (PCA) was performed on the variance‐filtered data, and the two principal components were retained to generate new data for hierarchical clustering. After hierarchical clustering, we used the receiver operating characteristic method in this cluster. Results: Seventy synthetic indole/indazole cannabinoids were classified into four clusters. The side chain of cluster 1 is mainly fluorobenzyl, cluster 2 is pentyl, cluster 3 includes compounds from several structures, and cluster 4 is mainly fluoropentyl. The most relevant characteristic ions are m/z 109, m/z 252, and m/z 253 for cluster 1; m/z 144 and m/z 214 for cluster 2; and m/z 232 and m/z 233 for cluster 4. Conclusions: This study provides a more objective and less time‐consuming solution for characterizing synthetic cannabinoids. And this work validates the ability of PCA to extract characteristic fragment ions. [ABSTRACT FROM AUTHOR]

Black ginseng is a new type of processed ginseng that is traditionally used in herbal medicine in East Asian countries. It is prepared from fresh, white, or red ginseng by undergoing a process of steaming and drying several times. However, the chemical differentiation of black ginseng with different processing levels is not well understood. The aim of this study was to propose a new method for discriminating and quantifying black ginseng. Six ginsenosides from black ginseng were accurately quantified, and based on this, the black ginseng samples were divided into incomplete and complete black ginseng. Ultrahigh-performance liquid chromatography–quadrupole-time of flight/mass spectrometry (UPLC-Q-TOF/MS) combined with a multivariate statistical analysis strategy was then employed to differentiate the two groups. A total of 141 ions were selected as analytical markers of black ginseng, with 45 of these markers being annotated by matching precise m/z and MS/MS data from prior studies. [ABSTRACT FROM AUTHOR]

The article offers information on the debate surrounding the authorship of the play "Arden of Faversham," with some scholars arguing that it was written by Thomas Kyd based on shared phrases with his accepted plays, while others contest this claim using quantitative analysis. The author aims to test the claim made by MacDonald P. Jackson that there are more unique trigrams shared between "Arden of Faversham" and Shakespeare's plays than between "Arden of Faversham" and play accepted as Kyd's.

This paper gives a brief comparison of the quantitative chemical analysis content in representative analytical chemistry textbooks by authors at Peking University and overseas. Specifically, the content of introduction, error and data analysis and treatment, as well as chemical equilibria and volumetric titration are evaluated. The compared textbooks cover largely the same basic contents, methods and ways to solve analytical problems. Each book presents the content in its own style, sequence, and point cut, providing diversified perspectives on analytical chemistry. Quantitative Chemical Analysis by authors at Peking University is a concise textbook which elucidates all the basic concepts, principles and methods in limited number of pages. Most overseas textbooks provide a detailed introduction of the basic physical chemistry perspective of chemical equilibria, thus, general chemistry course may not be a prerequisite. The future development of analytical chemistry and related disciplines, as well as the emergence of new analytical methods may become parts of the analytical chemistry textbooks. As a result, the chemical analysis part may be reduced as we cannot make the size of the textbook bigger and bigger without limit. Nevertheless, the procedure and steps to solve problems of analytical chemistry remains the same. In the future analytical chemistry textbooks, the basics and principles in the workflow of the analytical chemistry procedure, and errors and analytical data treatment are suggested to be enhanced. The language/terminology of analytical chemistry and figures of merit of analytical methods are suggested to be introduced. The way to solve complicated chemical equilibria should be further condensed based on the physical chemistry principle. All of the above are the basis for understanding how to solve an analytical chemistry problem, how to develop an analytical method, and how to validate a new analytical method. [ABSTRACT FROM AUTHOR]

This paper introduces the features and evolution of Quantitative Chemical Analysis textbook by authors at Peking University. In the evolution of each edition, the authors try to deliver the thought and way that analytical chemists solve problems. In particular, the authors emphasize on the basic theory and statistical tools, and illustrate the way to solve analytical problems with examples. [ABSTRACT FROM AUTHOR]

The development of new antimicrobial formulations for the treatment of animal infectious dermatitis is important as current antimicrobial treatments can have undesirable effects. The purpose of this study was to examine the in vitro antimicrobial activity of an Eryngium foetidum L. ethanolic extract against a bacterium, Staphylococcus pseudintermedius; a yeast, Malassezia pachydermatis; and three dermatophytes, Microsporum canis, Microsporum gypseum, and Trichophyton mentagrophytes; all of which are the most common animal skin pathogens causing dermatitis. A viscous semi-solid crude extract was obtained at a yield of 30.6% dry weight. Quantitative analysis of the chemical constituents of the extract by spectrophotometry revealed 3.62 mg GAE/g extract of total phenolic, 1.77 mg CE/g extract of total flavonoid, and 10.11 mg/g extract of total carotenoid contents. HPLC-DAD analysis of the carotenoid content showed that β-carotene and lutein were present at 5.17 and 4.43 mg/g extract, respectively. Antimicrobial activity by broth microdilution test found that the E. foetidum extract had MIC, MBC and MFC values in the range of 6.25 to 25.0 mg/ml; and the time-kill test indicated that this effect was both dose and time dependent. Ointment formulations containing the extract at concentrations of 5, 7.5 and 10% w/w had high microbicidal activity against the tested pathogens and retained their activity and physical properties after repeated freeze-thaw cycles. The results of this study show the potential of E. foetidum extract to be developed as a novel antimicrobial formulation for treatment of infectious dermatitis in pets. [ABSTRACT FROM AUTHOR]

Electronic cigarettes (e-cigarettes, vaping products) have become increasingly popular, with recent increases in use associated with closed systems delivering higher concentrations of nicotine. Most vaping products designed as an alternative to combustible cigarettes contain nicotine. A number of published studies have examined the reported concentrations of nicotine in vaping liquids (e-liquids) and found discrepancies between labelled and measured levels. Some discrepancy can also be explained by the lack of stability of nicotine in these types of products. Recently, a chemical analysis method for the quantitative determination of low and high levels of nicotine in vaping liquids was developed. This method uses dilution with acetonitrile prior to analysis with gas chromatograph mass spectrometry (GC-MS) in single ion monitoring mode (SIM). The developed method was validated using a laboratory-prepared vaping liquid as well as commercially available, nicotine-free products fortified with nicotine in the laboratory. The method detection limit (MDL) and the limit of quantitation (LOQ) for nicotine were calculated to be 0.002 mg/mL and 0.006 mg/mL, respectively. The newly developed method was applied to quantify nicotine in commercially available vaping liquids of various flavour profiles and across a wide range of nicotine concentrations, including those with nicotine salts. Furthermore, a subset of vaping liquids were analyzed to elucidate nicotine stability in various product subtypes. After a period of six months of accelerated storage to mimic one year, the overall mean percent of the original nicotine concentration remaining in the salt-based vaping products was 85% (minimum 64%, maximum 99%) while in the free-base nicotine products it was 74% (minimum 31%, maximum 106%). Nicotine stability in vaping liquids was found to be influenced by the nicotine form (pH) of formulation and its chemical composition. Non-targeted, qualitative analysis of chemical composition of vaping products showed that most constituents were identified and found to be remaining in the products following stability trials; however, three new compounds were tentatively identified in some vaping liquids at the end of the stability trials. Stability studies and the accurate quantitation of nicotine in vaping products can help inform product standards related to the safety, quality and utility of vaping products as a smoking cessation tool. [ABSTRACT FROM AUTHOR]

Mikecoxite, ideally (CHg4)OCl2, is the first mercury-oxide-chloride-carbide containing a C4– anion coordinated by four Hg atoms (a permercurated methane derivative) to be described as a mineral species. It was found at the McDermitt open-pit mine on the eastern margin of the McDermitt Caldera, Humboldt County, Nevada, U.S.A. It is monoclinic, space group P21/n, Z = 4; a = 10.164(5), b = 10.490(4), c = 6.547(3) Å, V 698.0(5) Å3. Chemical analysis by electron microprobe gave Hg 86.38, Cl 11.58, Br 0.46, C 1.81, sum = 100.23 wt%, and O was detected but the signal was too weak for quantitative chemical analysis. The empirical formula, calculated on the basis of Hg + Cl + Br = 6 apfu, is (C1.19Hg3.39)(Cl2.57Br0.05)Σ2.62, and the ideal formula based on the chemical analysis and the crystal structure is (CHg4)OCl2. The seven strongest lines in the X-ray powder diffraction pattern are [d (Å), I, (hkl)]: 2.884, 100, (230); 2.989, 81, (301, 301, 112, 112, 131, 131); 2.673, 79, (122, 122, 212, 212); 1.7443, 40, (060, 432, 432); 5.49, 34, (101, 101); 4.65, 32, (120); 2.300, 30, (312, 312). The Raman spectrum shows three bands at 638, 675, and 704 cm–1, well above the range characteristic of NHg4 stretching vibrations between 540 and 580 cm–1, that are assigned to CHg4 stretching vibrations. Mikecoxite forms intergrowths of bladed crystals up to 100 μm long that occur on granular quartz or in vugs associated with kleinite. It is black with a submetallic to metallic luster and strong specular reflections and does not fluoresce under short- or long-wave ultraviolet light. Neither cleavage nor parting were observed, and the calculated density is 8.58 g/cm3. In the crystal structure of mikecoxite, (C 4 − H g 4 2 +) groups link through O2– ions to form three-membered rings that polymerize into corrugated [CHg4OCl]+ layers with near-linear C4––Hg2+–O and C4––Hg2+–Cl linkages. The layers link in the third direction directly via weak Hg2+–O2– and Hg2+–Cl– bonds to adjacent layers and also indirectly via interlayer Cl–. A bond-valence parameter has been derived for (Hg2+–C4–) bonds: Ro = 2.073 Å, b = 0.37, which gives bond-valence sums at the C4– ions in accord with the valence-sum rule. The source of carbon for mikecoxite in the volcanic high-desert environment of the type locality seems to be methane, with the reaction catalyzed by microbiota through full mercuration of carbon atoms, beyond the first stage that produces the volatile and highly mobile methylmercury, [CH3Hg]+, a potent neurotoxin that accumulates in marine food chains. Both the mineral and the mineral name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2021-060). The mineral is named after Michael F. Cox (b. 1958), a founding member of the New Almaden Quicksilver County Park Association (NAQCPA) who was responsible for characterizing and remediating environmental mercury on-site and who recovered the rock containing the new mineral. [ABSTRACT FROM AUTHOR]

The global drive for a circular economy emphasizing sustainability in composite manufacturing processes has been the driving force for current ongoing research studies in natural fibers as sustainable substitutes for non-biodegradable synthetic fibers. The present study was carried out to characterize Dombeya buettneri fiber (DBF) extracted manually from the bark of the plant stem. Determination of physical and mechanical properties, quantitative chemical analysis, Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis and scanning electron microscopy were used to characterize the extracted fiber. Fiber constituents and XRD results showed higher cellulose content (58.45%), crystallinity index (62.32%) and percent crystalline (72.63%). The fiber had a crystallite size of 2.16 nm as determined using the Debye-Scherrer's equation while FTIR analysis confirmed the presence of various functional groups of lignin, hemicellulose and cellulose on the fiber structure. The results revealed that DBF fiber had a thermal resistance that is up to 229.57°C with a maximum thermal degradation temperature of 356.27°C. Based on the results of this research that are comparable with other studies on cellulosic fiber, DBF fiber has a great potential as an alternative reinforcement for the development of polymer-based bio-composites. [ABSTRACT FROM AUTHOR]

The results of studies on the intensification of the dealkalization process of alkaline silicate industrial and synthesized glasses with acid gases are analyzed and summarized. The composition of the reaction products of glasses with gaseous reagents is identified using X-ray phase analysis, X-ray spectral electron probe microanalysis, thermal analysis, flame photometry, and quantitative chemical analysis. The physicochemical properties of industrial glassware modified with gaseous reagents are determined in laboratory and factory experiments. Ways of intensifying the dealkalization process of silicate glasses with acid gases are discussed. [ABSTRACT FROM AUTHOR]

Once a chemical production accident occurs in a chemical plant, it often causes serious economic losses, casualties, and environmental damage. Statistics show that many major accidents in the production and storage of chemicals are mainly caused by human factors. This article considers the influence of the human factor and proposes a quantitative analysis model of a chemical plant based on a Bayesian network. The model takes into account the main human factors in seven aspects: organization, information, job design, human system interface, task environment, workplace design, and operator characteristics. The Bayesian network modeling method and simulation were used to predict the safety quantitative value and safety level of the chemical plant. Using this model, we can quickly calculate the safe quantitative ratio of each factor in the chemical plant. Through the safety quantitative value, safety level, and sensitivity analysis, the safety hazards of chemical companies can be discovered. Immediate improvements of potential safety hazards in chemical plants are very effective in preventing major safety accidents. This model provides an effective method for chemical park managers to monitor and manage chemical plants based on quantitative safety data. [ABSTRACT FROM AUTHOR]

Phytochemicals present in medicinal plants (herbs, shrubs, and trees) are endowed with high antimicrobial and antioxidant properties. The aim of this work was to study the chemical composition, antioxidant, and antifungal activities of Tristemma mauritianum, Crassocephalum bougheyanum, and Lavigeria macrocarpa. Chemical composition of the plant extracts was determined using standard methods. The antioxidant activities were performed using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), nitric oxide (NO), and hydroxyl (OH) scavenging assays. The antifungal activity of plant extracts and their combinations with antifungals was evaluated against eleven Candida spp. using the broth microdilution method by determining the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). The quantitative chemical analysis of the extracts of T. mauritianum, L. macrocarpa, and C. bougheyanum showed that they contain phenols, tannins, and flavonoids that vary according to the plant species and extracts. All the plant extracts presented promising antifungal (MIC = 64–2048 µg/mL) and antioxidant activities. The extract of T. mauritianum displayed the highest antifungal (MIC = 64–256 µg/mL) and antioxidant (IC50 = 19.052 ± 1.11 μg/mL) activities which can be explained by its high phenolic content. Interestingly, extracts of T. mauritianum, L. macrocarpa, and C. bougheyanum displayed synergistic effects (fractional inhibitory concentration index, FICI ≤ 0.5) with ketoconazole against clinical resistant isolates. The results of the present study demonstrate promising antifungal and antioxidant activities of the tested plants that are associated to their phenol, tannin, and flavonoid contents. Hence, extracts of T. mauritianum and L. macrocarpa could be deeply investigated as antifungal alone and in combination with conventional antifungal drugs to treat infections caused by Candida spp. [ABSTRACT FROM AUTHOR]