Mixture Of Products Research Articles

Structural and Functional Analyses of Inhibition of Human Dihydroorotate Dehydrogenase by Antiviral Furocoumavirin.

Natural products are important sources of seed compounds for drug discovery. However, it has become difficult in recent years to discover new compounds with valuable pharmacological activities. On the other hand, among the vast number of natural products that have been isolated so far, a considerable number of compounds with specific biological activities are thought to be overlooked in screening that uses biological activity as an index. Therefore, it is conceivable that such overlooked useful compounds may be found by screening compound libraries that have been amassed previously through specific assays. Previously, NPD723, a member of the Natural Products Depository library comprised of a mixture of natural and non-natural products developed at RIKEN, and its metabolite H-006 were found to inhibit growth of various cancer cells at low nanomolar half-maximal inhibitory concentration. Subsequent analysis revealed that H-006 strongly inhibited human dihydroorotate dehydrogenase (DHODH), the rate-limiting enzyme in the de novo pyrimidine biosynthetic pathway. Here, we elucidated the crystal structure of the DHODH-flavin mononucleotide-orotic acid-H-006 complex at 1.7 Å resolution to determine that furocoumavirin, the S-enantiomer of H-006, was the actual inhibitor. The overall mode of interaction of furocoumavirin with the inhibitor binding pocket was similar to that described for previously reported tight-binding inhibitors. However, the structural information together with kinetic characterizations of site-specific mutants identified key unique features that are considered to contribute to the sub-nanomolar inhibition of DHODH by furocoumavirin. Our finding identified new chemical features that could improve the design of human DHODH inhibitors.

Antimicrobial and anti-inflammatory effects of BenTooth: A natural product blend of burdock root, persimmon leaf extracts, and quercetin on periodontal disease

Periodontal disease represents a condition that exhibits substantial global morbidity, and is characterized by the infection and inflammation of the periodontal tissue effectuated by bacterial pathogens. The present study aimed at evaluating the therapeutic efficacy of BenTooth, an edible natural product mixture comprising burdock root extract, persimmon leaf extract and quercetin, against periodontitis both in vitro and in vivo. BenTooth was examined for antimicrobial properties and its impact on cellular responses related to inflammation and bone resorption. Its effects were also assessed in a rat model of ligature-induced periodontitis. BenTooth demonstrated potent antimicrobial activity against P. gingivalis and S. mutans. In RAW264.7 cells, it notably diminished the expression of inducible nitric oxide synthase and cyclooxygenase-2, as well as reduced interleukin-6 and tumor necrosis factor-α levels triggered by P. gingivalis-derived lipopolysaccharide. Furthermore, BenTooth inhibited osteoclastogenesis mediated by the receptor activator of nuclear factor κB ligand. In the rat model, BenTooth consumption mitigated the ligature-induced expansion in distance between the cementoenamel junction and the alveolar bone crest and bolstered the bone volume fraction. These results present BenTooth as a potential therapeutic candidate for the prevention and remediation of periodontal diseases.

Secreted d-allulose 3-epimerase for rare d-allulose biosynthesis and yeast-assisted isomer removal from d-allulose

d-Allulose is a low-calorie rare sugar with multiple physiological functions, primarily produced through enzymatic isomerization with the key enzyme d-allulose 3-epimerase (DAEase). DAEase from a Clostridia bacterium (CDAE) was successfully expressed in food-grade Bacillus subtilis and substantially secreted into the extracellular medium (155.50 U/mL), achieving the highest reported extracellular activity among DAEases to date. The unique secretion behavior of CDAE without signal peptide was ascribed to cell membrane permeabilization and cell lysis. Furthermore, the secreted CDAE was employed for the synthesis of d-allulose from fructose or glucose via reversible isomerization. Yeast fermentation was implemented to selectively consume coexisting isomers in the product mixture. This process achieved a removal rate exceeding 99% for glucose and fructose while preserving d-allulose, resulting in a high-content d-allulose syrup (96.8% on a dry weight basis). Collectively, the efficient secretion of CDAE and cost-effective removal of isomers contribute to the economic production and separation of d-allulose.

Exploration of Hierarchically Porous Perovskite Ba0.5Sr0.5FeO3 Catalyst Through Experimental and Computational Investigations for Sustainable Synthesis of Acrolein

AbstractBa0.5Sr0.5FeO3, SrMn0.5Fe0.5O3, and BaMn0.5Fe0.5O3 perovskite catalysts were synthesized via the hydrothermal method. The developing perovskite catalysts with dual bed, redox and acid/base sites, for direct oxidation reactions is one of the recent/important research ideas. Therefore, this study deals with the impact of substituting A and/ or B sites on the catalytic oxidative reactivity of mixed oxides perovskite catalysts. Then, their reactivity was tested in a single reactor oxidative coupling of methanol/ethanol mixture for sustainable acrolein production. The Ba0.5Sr0.5FeO3 perovskite sample has the highest catalytic performance at low temperatures (300○C) with 78% acrolein selectivity, followed by SrMn0.5Fe0.5O3 (65%), then BaMn0.5Fe0.5O3 (58%). The enhanced catalytic reactivity of Ba0.5Sr0.5FeO3 is associated with its effective acidic property and the ability to form O-vacancies easily, so, the strong proclivity for C–C coupling formation.

Histopathological investigation of some facial cosmetic products mixture exposed to fingerlings of mud catfish <i>(Clarias gariepinus</i>)

Cosmetics are one of the major pollutants in the aquatic ecosystem due to the quantum of production to meet the astronomical demand  of users that eventually becomes harmful to organisms. Changes in physic-chemical parameters such as potential of hydrogen (pH),  Electrical conductivity (EC), Temperature (T oC) Dissolved oxygen (DO) were investigated at the beginning and after 96 hours of cosmetic  exposure. This study also investigated the effects of four facial cosmetic products (Powder, foundation, concealer, and primer) histopathologically in fingerlings of Clarias gariepinus (gills) exposed to binary, trinary, and quaternary mixtures in o laboratory bioassays  for 48 hours and 96 hours. The results of pH, T C, EC and DO ranged from 6.21 - 6.64, o 25.40 - 26.70 oC, 0.04 - 0.14 mS/cm, and  10.00 -12.00 mg/l respectively. The joint action toxicity evaluation of the binary, trinary, and quaternary mixtures of the cosmetics  prepared based on an equitoxic ratio against the test organism was in concordance with the model of synergism. Results showed the  prevalence of severe lamellar necrosis in the gills of C. gariepinus which was observed across all combinations except in the combinations  of Powder + Primer as well as Powder + Foundation + Concealer + Primer. Moderate lamellar necrosis and hypertrophied  epithelium were observed in fish exposed to a mixture of Powder + Foundation + Concealer. The results obtained in this study suggested  that the presence of facial cosmetics in the aquatic ecosystem could be dangerous to fish and subsequently human health via  biomagnification. Therefore, there is an urgent need for environmental regulators to enforce safety standards for the emission of these  selected cosmetics wastes into the waterways to prevent damage to aquatic organisms and public health issues.  

Ferrocene-Based N-Heterocyclic Silylenes: Monomeric Silanechalcogenones, Silanimines, Silirenes, and Insertion Products with P4.

The stable ferrocene-based N-heterocyclic silylenes fc[(N{B})2Si] (A; fc = 1,1'-ferrocenylene, {B} = (HCNDipp)2B, Dipp = 2,6-diisopropylphenyl) and fc[(NDipp)2Si] (B) are compared in a study focussing on their reactivity towards a range of small to moderately sized molecular substrates, viz. P4, S8, Se8, MesN3 (Mes = mesityl), RC≡CH, and RC≡CR (R = Ph, SiMe3). The Dipp-substituted congener B exhibits a more pronounced ambiphilicity and is sterically less congested than its 1,3,2-diazaborolyl-substituted relative A, in line with the higher reactivity of the former. The difference in reactivity is obviously due more to electronic than to steric reasons, as is illustrated by the fact that both A and B react with the comparatively bulky substrate MesN3 under mild conditions to afford the corresponding silanimine fc[(N{B})2Si=NMes] and fc[(NDipp)2Si=NMes], respectively. The heavier ketone analogues fc[(N{B})2Si=E] (E = S, Se, Te) are readily available from A and the corresponding chalcogen. In contrast, the reaction of the more reactive silylene B with elemental sulfur or selenium is unspecific, affording product mixtures. However, fc[(NDipp)2Si=Se] is selectively prepared from B and (Et2N)3PSe; the Te analogue is also accessible, but crystallises as head-to-tail dimer.

Direct Oxidations of meso-Tetrakis(pentafluorophenyl)porphyrin: Porphotrilactones and Entry into a Nonbiological Porphyrin Degradation Pathway.

The direct oxidations of meso-tetrakis(pentafluorophenyl)porphyrin using cetyltrimethylammonium permanganate (CTAP), RuCl3/Oxone/base or Ag+/oxalic acid each generate distinctive product mixtures that may contain, inter alia, porpho-mono-, di-, and trilactones. The CTAP and RuCl3/Oxone/base oxidations also generate a unique open chain tripyrrin derived from the degradation of a porpholactone oxazolone moiety. Thus, its formation and structure are distinctly different from all biological or nearly all other nonbiological biliverdin-like linear porphyrinoid degradation products that are derived from ring cleavages between the pyrrolic building blocks.

Historical charcoal production as a factor in soil cover heterogeneity in a fluvioglacial landscape − A case study from northern Poland

Although in situ wood thermal processing, as a common practice in European forests in historical times, has been confirmed in many studies, the environmental implications of that process remain poorly explored. In this study, we focused on evaluating the impact of that process on forest vegetation and soil cover heterogeneity in a fluvioglacial landscape dominated by Brunic Arenosols. This study covered three 70–95-year-old stands of Scots pine in northern Poland. Three soil profiles, including from the relict charcoal hearth (RCH), from the surrounding ditch and a control, were examined from each stand, as well as associated vegetation. The studies showed that 19th century charcoal production platforms were overgrown with 20–60% fewer plant species than control stands. The effect on soils varied according to their characteristics. The presence of anthropogenic horizons consisting of a mixture of burnt soil material, ashes, charcoal particles, and other products of wood pyrolysis was the most distinguishing feature of RCH soils classified as Spolic Technosols (Arenic, Dystric, Pyric, Protospodic, Transportic). Typically, these horizons were characterised by lower bulk density, and higher porosity, as well as higher contents of total organic carbon, nitrogen, and exchange cations than the control soils. The differences between the RCH and control soils were highlighted by a comparison between the pools of the components in a soil column (pedon). Clear tendencies were not recorded for pH, the phosphorus content and stocks, the forms of iron and aluminium, the saturation of the soil sorption complex with bases or the trophic index. This may be due to the long-term neutralising effect of forest vegetation, dominated by Scots pine. Moreover, the results of our study may indicate the problem of toxicity of the RCH soils, which should be undertaken, considering the utilitarian importance of the issue.

The combined effects of preservative chemicals in consumer products: An analysis using embryonic and adult zebrafish

Benzisothiazolinone (BIT) and propyl paraben (PP) are preservatives in cleaning products; however, their toxicities are not well understood. In this study, zebrafish embryos were exposed to BIT, PP, and mixtures of both for 96 h to investigate the effects on growth hormone (GH), insulin-like growth factor-1 (IGF-1), and the transcription of 19 genes related to the GH/IGFs axis. Concentrations of BIT and PP were measured in the whole body of larvae. Zebrafish pairs were also exposed to BIT, PP, and mixtures for 21 d to evaluate the effects on sex hormones, histology in gonad, and transcription of 22 genes related to the hypothalamus-pituitary-gonad axis and vitellogenin. The mixtures had potentiation effects on development, reproduction, hormones, and gene transcripts than individual exposure. Larvae exposed to 229 μg L−1 BIT, 64.5 μg L−1 PP, and mixtures showed reduced growth. Decreased GH and IGF-1 levels were supported by gene regulation associated with the GH/IGFs axis. In larvae, reactive oxygen species, superoxide dismutase, catalase, and glutathione peroxidase levels were increased under all exposures. The gonadosomatic index in males and number of eggs decreased after mixture exposure. In females exposed to mixtures, the percentage of atretic follicle in ovary was significantly increased. The significant decrease in testosterone in males and significant decrease in 17β-estradiol in females exposed to mixtures suggest anti-estrogenic and anti-androgenic potential. Thus, preservative mixtures in consumer products may be more toxic than the individual substances, which is important for managing the risks of mixing preservatives.

Polyphosphorus compounds derived from P4 conversion with sterically demanding cobalt complexes

The conversion of P4 with [CpBnCo(CO)2] (CpBn = C5(CH2C6H5)5) under thermal conditions gives almost exclusively the P10 complex [(CpBnCo)4(μ4‐η4:η4:η2:η2:η1:η1‐P10)]. However, its reaction with [CpBnCo]n, under mild conditions afforded a mixture of products including the P8 species [(CpBnCo)3(μ3‐η4:η2:η2:η1:η1‐P8)] and a rare Co3 cluster [(CpBnCo)2Co(μ3‐η5:η2:η1:η1‐C40H33)(μ‐H)(μ3‐H)]. The products were studied in solution by multinuclear NMR spectroscopy and mass spectrometry and, for some compounds in the solid state, by single crystal X‐ray diffraction.

Glycerol Electrolyzer with Graphite Anode and Cathode Produces Carbonyl Compounds and Hydrogen: Background Electrocatalysis of a "Nonparticipating" Current Collector.

This study unveils a novel role of bare graphite as a catalyst in glycerol electrooxidation and hydrogen evolution reactions, challenging the prevailing notion that current collectors employed in electrolyzers are inert. Half-cell experiments elucidate the feasibility of glycerol oxidation and hydrogen production on bulk graphite electrodes at potentials exceeding 1.7 V. The investigation of varying glycerol concentrations (0.05 to 1.5 mol L-1) highlights a concentration-dependent competition between glycerol electrooxidation and oxygen evolution reactions. Employing an H-type glycerol electrolyzer, polarization curves reveal significant activation polarization attributed to the low electroactivity of the anode. Glycerol electrolysis at different concentrations yields diverse product mixtures, including formate, glycolate, glycerate, and lactate at the anode, with concurrent hydrogen generation at the cathode. The anolyte composition changes with glycerol concentration, resulting in less-oxidized compounds at higher concentrations and more oxidized compounds at lower concentrations. The cell voltage also influences the product formation selectivity, with an increased voltage favoring more oxidized compounds. The glycerol concentration also affects hydrogen production, with lower concentrations yielding higher hydrogen amounts, peaking at 3.5 V for 0.05 mol L-1. This model quantitatively illustrates graphite's contribution to current and product generation in glycerol electrolyzers, emphasizing the significance of background current and products originating from current collectors if in contact with the reactants. These results have an impact on the efficiency of the electrolyzer and raise questions regarding possible extra non-noble "nonparticipating" current collectors that could affect overall performance. This research expands our understanding of electrocatalysis on graphite surfaces with potential applications in optimizing electrolyzer configurations for enhanced efficiency and product selectivity.

Unexpected formation of FeIIFeIIIFeII- and FeIIFeIIFeII-trinuclear hexapyridineoximate helicates: synchrotron single-crystal X-ray structures

Template condensation of 2-acetylpyridineoxime with butyl ester of 1,3-propanediboronic acid in the presence of iron(II) affords a poorly separable mixture of complex products. Similar results were observed when Fe3+ ions were used for cross-linking in place of the diboronic acid. Prolonged crystallization of these mixtures gave crystals of perchlorate salts of a FeIIFeIIIFeII-trinuclear hexapyridineoximate cation and of an analogous FeIIFeIIFeII-intracomplex that crystallize with chloroform and dichloromethane solvent molecules, respectively. Both complexes were characterized by synchrotron single-crystal X-ray diffraction (XRD) experiments. The Fe–N distances of the two ‘terminal’ iron cations are virtually the same between these trinuclear complexes and unambiguously support assignments of oxidation number +2 and low-spin state (S = 0). The centers of the FeN6 -coordination polyhedra adopt geometries resembling trigonal antiprisms with distortion angles φ of approximately 40°. The FeO6 -coordination polyhedra possess an almost ideal Oh geometry with φ close to 60°. Each of these iron(II) or iron(III) µ3 -metallocenters acts as a bifunctional Lewis acid that cross-links two pseudoclathrochelate entities, formed by the ‘terminal’ iron(II) ions, to give an almost linear (the corresponding intramolecular Fe(2)…Fe(1)…Fe(3) angles are close to 180°) helical cation or intracomplex.

The Overlooked Potential of Sulfated Zirconia: Reexamining Solid Superacidity Toward the Controlled Depolymerization of Polyolefins.

Closed-loop recycling via an efficient chemical process can help alleviate the global plastic waste crisis. However, conventional depolymerization methods for polyolefins, which compose more than 50% of plastics, demand high temperatures and pressures, employ precious noble metals, and/or yield complex mixtures of products limited to single-use fuels or oils. Superacidic forms of sulfated zirconia (SZrO) with Hammet Acidity Functions (H0) ≤ - 12 (i.e., stronger than 100% H2SO4) are industrially deployed heterogeneous catalysts capable of activating hydrocarbons under mild conditions and are shown to decompose polyolefins at temperatures near 200 °C and ambient pressure. Additionally, confinement of active sites in porous supports is known to radically increase selectivity, coking and sintering resistance, and acid site activity, presenting a possible approach to low-energy polyolefin depolymerization. However, a critical examination of the literature on SZrO led us to a surprising conclusion: despite 40 years of catalytic study, engineering, and industrial use, the surface chemistry of SZrO is poorly understood. Ostensibly spurred by SZrO's impressive catalytic activity, the application-driven study of SZrO has resulted in deleterious ambiguity in requisite synthetic conditions for superacidity and insufficient characterization of acidity, porosity, and active site structure. This ambiguity has produced significant knowledge gaps surrounding the synthesis, structure, and mechanisms of hydrocarbon activation for optimized SZrO, stunting the potential of this catalyst in olefin cracking and other industrially relevant reactions, such as isomerization, esterification, and alkylation. Toward mitigating these long extant issues, we herein identify and highlight these current shortcomings and knowledge gaps, propose explicit guidelines for characterization of and reporting on characterization of solid acidity, and discuss the potential of pore-confined superacids in the efficient and selective depolymerization of polyolefins.

Hidden in plain sight: revisiting the synthesis, characterisation, degradation and the intricate relationship between Scheele’s green and Emerald green

Carl Wilhelm Scheele's notorious toxic pigment, commonly referred to as “Scheele's green” often resulted in a mixture of products with unknown chemical composition. Positive identification of the pigment has been limited to Raman spectroscopy and indirect analysis using FTIR and XRD methods. Despite these techniques, reported occurrences of the pigment in heritage samples are scarce, suggesting that Scheele’s green is rarely reported due to challenges in its characterisation rather than infrequent use. Regarding the degradation of Cu-As green pigments, common assumptions suggest dissociation in acidic pH conditions, generating mobile arsenic and copper ions, followed by oxidation to As(V), which can co-precipitate with Fe, Al, and Ca ions. This study reproduces the fabrication of Scheele's green using historical recipes, focusing on maintaining the pH of the arsenite solution at 9.3. The research explores its relationship with Emerald green, the challenges associated with their identification, and addresses common misconceptions about the degradation of such pigments. Maintaining the pH at 9.3 proved influential in obtaining a crystalline product with an intense Raman signal, aligning with the widely accepted spectra of Scheele’s green. However, Raman spectra from amorphous Cu-As samples consistently exhibited broad bands at 288 and 845 cm−1, prompting a proposed modification for a dual representation of the pigment: the “common” form with broad bands and the “uncommon” or crystalline form as reported in the literature. Demonstrating that the crystalline form shares nearly identical Raman and FTIR spectra implies an identical chemical composition to Trippkeite. Evidence presented highlights that Cu-As based pigments contain free copper, arsenite and arsenate ions prone to migration, challenging commonly described degradation pathways. The hypothesis presented here, that Emerald green synthesis may inadvertently yield small amounts of Scheele’s green urges caution in pigment identification using Raman spectroscopy. Additionally, the study reveals, for the first time, the occurrence of Scheele’s green in a book, with particles exhibiting a spherulite form, challenging identification of Emerald green solely based on morphology.

Facile recovery of lithium as Li2CO3 or Li2O from α-hydroxy-carboxylic acid chelates through pyrolysis and the decomposition mechanism

Chelation of lithium with readily available α-hydroxy carboxylic acids is a sustainable recovery method from spent Li-ion battery wastes as well as a possible lithium extraction method. In this work pyrolytic decomposition of a series of selected lithium chelates of glycolic, lactic, malic and tartaric acid were studied and compared with lithium acetate as a potential lithium recovery method from chelates. In thermogravimetric analysis, the four α-hydroxy carboxylic acid chelates studied showed lower initial decomposition temperatures in the 313–356 °C range, in comparison to the lithium acetate with an initial decomposition temperature of 444 °C. The ease of decomposition of α-hydroxy carboxylic acid chelates may be due to their favorable decomposition pathways through dimerization and tetramerization of α-hydroxy acids via esterification and free radical coupling mechanisms leading to a complex mixtures of products; including alkenes, dienes and enones. The lithium α-hydroxy carboxylic acid chelate pyrolysis residue formed above 300 °C was identified as lithium carbonate and further heating above 700 °C, lithium carbonate decomposes to lithium oxide, allowing the recovery of lithium as Li2CO3 or Li2O.

Thermal decomposition of polyolefins under different oxygen content. Composition of products and thermal effects

The thermal decomposition of polyethylene and polypropylene was studied under conditions of different oxygen contents in the carrier gas in the temperature range of 200–600 °C. The effect of adding an oxidizing agent to the carrier gas was studied at (O2/N2)mol ratios of 0/100; 1/99; 2/98; 4/96; 6/94; 10/90; 21/79. Combined TG-FTIR and TG-DSC techniques were used in the studies. Based on FTIR spectra, a quantitative and qualitative analysis of the process gaseous products was performed. The study showed that the thermal degradation of polyolefins can lead to mixtures of saturated and unsaturated hydrocarbons, which are an attractive substitute for natural gas for hydrogen production. The molar ratio of saturated/unsaturated hydrocarbons for PE and PP is 3/2. The composition of the gas product mixture as well as the heat balance of the process can be controlled by adjusting the oxygen concentration in the carrier gas. With a content of 3%O2 in the carrier gas for PE and 4%O2 for PP, autothermal conditions of the thermal processing of polyolefins are achieved. The addition of oxygen accelerates the transformation of polyolefins and thus lowers the optimal process temperature. The CxHyO and CO mixture, coexisting with the hydrocarbon mixture in some process variants, can be converted by the water shift reaction into a mixture of H2 and CO2.

Facile preparation of environmental benign LED white light active humic acid nanolayer coated titanium dioxide photocatalyst for bisphenol A degradation

Natural organic matter is a mixture of microbial decomposition products widely found in surface and groundwater. These organic materials have great potential as carbon-based precursors for chemical synthesis. This work demonstrated the development of a green photocatalyst via a facile adsorption process that combined colloidal titanium dioxide (TiO2) with humic acid. The resulting photocatalyst was visible light active and able to completely degrade 5 mg/L of BPA within 6 h under the irradiation of energy-efficient LED white light. The first-order kinetic rate constant of the reaction was determined to be 1.7 × 10−2 min−1. The enhanced photocatalytic activity was attributed to the decreased band gap energy and effective charge separation that limits the photogenerated electron-hole recombination. The outcome of this research opened an opportunity for the development of sustainable functional materials using natural organic matter.

Enforcing Metal-Arene Interactions in Bulky p-Terphenyl Bis(anilide) Complexes of Group 2 Metals (Be-Ba): Potential Precursors for Low-Oxidation-State Alkaline Earth Metal Systems.

An extremely bulky p-terphenyl bis(aniline), p-C6H4{C6H4[N(H)TCHP]-2}2 (TCHP = 2,4,6-tricyclohexylphenyl) TCHPTerphH2, has been developed. Deprotonation of a less bulky analogue, DipTerphH2 (Dip = 2,6-diisopropylphenyl), with BePh2 affords the bimetallic system, [(BePh)2(μ-DipTerph)] 1. Treating either TCHPTerphH2 or DipTerphH2 with Mg{CH2(SiMe3)}2 gives the monomeric bis(anilide) complexes [Mg(ArTerph)] (Ar = Dip 2, TCHP 3) which display rare examples of η6-arene coordination to the metal center. Treating 2 with THF leads to partial dissociation of the Mg···arene interaction and formation of [Mg(DipTerph)(THF)] 4. Reactions of the bis(aniline)s with the group 2 metal amides [M{N(SiMe3)2}2] afford dimeric, structurally analogous compounds [{M(ArTerph)}2] (Ar = Dip, M = Ca 5, Sr 6, Ba 7; Ar = TCHP, M = Ca 8, Sr 9, Ba 10) which display intermolecular M···arene interactions in the solid state. Computational studies have shown that the intramolecular M···η6-arene interactions in models of the ether-free metal bis(anilide) compounds are largely electrostatic in nature. Reductions of these compounds with alkali metals led to mixtures of unidentified products.

[Distribution Characteristics, Source Analysis and Ecological Risk Assessment of Heavy Metals in the Typical Industry Reclaimed Soil].

To further explore the characteristics of heavy metal pollution and the ecological risk of typical industries in reclaimed soil, based on data from 315 different depth profiles of soil samples collected from 49 plots in Jiading District, Shanghai, the geo-accumulation index and potential ecological risk index were used to evaluate the contents and potential ecological risk of seven heavy metals, namely Cd, Pb, Cu, Zn, Ni, Hg, and As. The APCS-MLR receptor model and PMF positive matrix factorization model were employed to analyze the pollution sources. The results showed that:① except for As, the contents of other heavy metals in the soil of the study area exceeded the Shanghai soil background values to varying degrees. The contents of Cd, Pb, Cu, Zn, Ni, and Hg in the surface soil were 3.54, 2.34, 2.91, 1.20, 3.75, and 4.40 times the background values, respectively. The contents of heavy metals in the soil decreased with the increase in depth, and heavy metals were enriched to a certain extent in the surface soil, indicating that human activities had an impact on the distribution of heavy metals in the soil. ② The APCS-MLR and PMF receptor models identified four main sources of soil heavy metals in the study area. Source 1 (Cu, Zn, and Pb) was a mixture of metal products and automobile manufacturing, source 2 (Ni and Cd) was electroplating enterprises, source 3 (Hg) was mainly from chemical enterprises, and source 4 (As) was natural. The combined use of the two receptor models further improved the accuracy and credibility of source identification. ③ The geo-accumulation index in descending order was Hg(1.54)>Ni(1.32)>Cd(1.21)>Cu(0.96)>Pb(0.64)>Zn(-0.33)>As(-1.02). The potential ecological risk index showed that the comprehensive potential ecological risk index RI value in the study area ranged from 32.50 to 4 910.97, with a mean of 321.40, indicating a strong potential ecological risk. The pollution values of heavy metals Hg, Ni, and Cd in industrial site soil deserve further attention for re-development and utilization purposes.

Minimum work associated with separating nitrogen from air: An exergy analysis

Background Nitrogen is essential for a variety of industries, including heat treatment, laser cutting, fire protection, and food packaging. Many companies in these industries obtain nitrogen via on-premises air separation processes. The three main processes for separating nitrogen from ambient air are cryogenic distillation, membrane separation, and pressure-swing adsorption (PSA). Improvements to these processes will likely focus on increasing efficiency, resulting in reduced environmental impact owing to less electrical power demand and opportunities for economic incentives. Regardless of the process utilized, a minimum theoretical amount of work input is required to obtain nitrogen gas at different pressures and concentrations compared to ambient conditions. Methods An equation was derived to evaluate the total exergy (including thermo-mechanical and chemical exergy) of product and exhaust mixtures resulting from air separation, indicating the minimum theoretical work input as a function of the product pressure, purity, and process recovery rate. This analysis considered an air separation system as a black box, with the input, output, and exhaust assumed to be ideal gas mixtures of nitrogen and oxygen at 15°C. The analysis applies to cryogenic distillation if the product and exhaust mixtures return to the gas phase. Results In general, the minimum required work input increases with product purity and recovery rate. Plots of minimum theoretical work versus product purity and recovery rate were made for two product pressures (atmospheric and 800 kPa) to show the behavior of the derived equation. Conclusions The analysis allows for direct efficiency (based on the second law of thermodynamics) comparisons between existing processes and future technological innovations in the field of air separation. Actual air separation systems have low efficiencies compared to ideal systems; actual PSA systems were estimated to have second law efficiencies of 5.5–11.2%. Therefore, there is great potential for improvements to current air separation systems.