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Abstract The environmental risk of secondary effluent has caused increasing attention in recent years, the negative effect of dissolved effluent organic matters (dEfOM) and organic micro-pollutants (OMPs) was a hot research point. In this research, the degradation behavior of dEfOM and fourteen OMPs in the ozonation was revealed using spectroscopic and chromatographic tools. Ozonation was effective for reducing UV 254 , but had limited effect in dissolved organic carbon reduction. The dEfOM with shorter absorption wavelength was preferentially removed in the ozonation (230 nm > 240 nm > 254 nm) and high molecular weight humics was largely reduced by the ozonation. Soluble microbial by-products were more reactive with ozone than humic acid as reflected by the fluorescence. Degradation behavior of the OMPs was identified based on their elimination kinetics and molecular structures and a simplified classification method was proposed. The group I OMPs (logk O3 >5) showed high removal efficiency with 1 mg/L of ozone, while the removal of group II OMPs (1< logk O3 <5) was largely dependent on the ozone dose. The C C bond, deprotonated amidogen, phenolic, aniline and anisole groups in these OMPs structures were the main reaction sites with ozone. The group III OMPs without active groups in the molecules showed slight removal in the ozonation. Moreover, genotoxicity and estrogenic activity were simultaneously analyzed for further evaluation on the risk of the effluent. The genotoxicity and estrogenic activity of the secondary effluent were 73.46 μg 4-NQO/L and 519.86 ng E2/L, respectively and an ozone dose of 10 mg/L could reduce the bio-toxicity to the detection limit. Highlights • 2D-COS, GPC and fluorescence were integrated to characterize dEfOM evolution during ozonation. • 14 structural diverse OMPs were investigated in wastewater matrix during ozonation. • The relationship of degradation to structural features of OMPs during ozonation was revealed. • Genotoxicity and estrogenic activity were used to evaluate the risk of ozonated wastewater. [ABSTRACT FROM AUTHOR]

Abstract Hydrogen, which holds tremendous promise as a new clean energy option is considered as an efficient source of primary energy. Unluckily, hydrogen storage presents the most crucial difficulty restricting utilization of hydrogen energy for real applications. However, Mg metal is the best known cheap solid-state hydrogen storage media with high hydrogen capacity and operational cost effectiveness; it shows high thermal stability and poor hydrogenation/dehydrogenation kinetics. In the present work we have succeeded to prepare nanocrystalline MgH 2 powders doped with a mixture of 8 wt% Nb 2 O 5 /2 wt% Ni nanocatalytic system. The synthesized nanocomposite powders possessed superior hydrogenation/dehydrogenation kinetics (2.6 min/3 min) at relatively low temperature (250 °C) with long cycle-life-time (400 h). The powders were consolidated into green-compacts, using cold pressing technique. The compacts were utilized as solid-state hydrogen source needed for charging a battery of a cell-phone device, using integrated Ti-tank/commercial proton-exchange membrane fuel cell system. Graphical abstract Image 1 Highlights • Synthesizing of nanocrystalline MgH 2 powders by reactive ball milling. • Doping MgH 2 with Nb 2 O 5 /Ni powders to enhance uptake/release kinetics. • Fabrication of MgH 2 /10 wt% (8 Nb 2 O 5 /2 Ni) buttons by cold pressing approach. • Employing the buttons for charging a cell phone battery via PEM fuel cell. [ABSTRACT FROM AUTHOR]

The elimination of carbon dioxide (CO 2 ) using water-based nanofluids (NFs) in a hollow fiber membrane contactor (HFMC) using polypropylene (PP) membrane was experimented. Gas flows in the shell, while NF flows in the fibers. Metal oxide nanoparticles (NPs) such as aluminum oxide (Al 2 O 3 ), titanium dioxide (TiO 2 ) and silica (SiO 2 ) in the concentrations of 0.05, 0.1 and 0.2 wt % were used in the experiments. Some factors such as gas flow rates, NPs type, NF temperature, NP concentration, as well as the effect of particle size on the separation were investigated. The results clearly show that the highest flux of CO 2 occurred for 0.2 wt % concentration of Al 2 O 3 NFs. Mass transfer flux enhancement (MTFE) was defined as the relative mass transfer flux (MTF) of CO 2 in the NFs with respect to the MTF of CO 2 in the de-ionized water as the base fluid. MTFE changed from 1.29 to 2.25 for the Al 2 O 3 NFs. Among all the results, the best result was obtained for Al 2 O 3 (40 nm) at 1.6 Lit/min liquid flow rate, 25 °C liquid temperature, 5 Lit/min gas flow rate and 40% inlet CO 2 concentration which is 98.9% CO 2 removal. Finally, a new correlation was developed for the Sherwood ( Sh ) number for the CO 2 mass transfer in the NFs flowing in the fibers. Sh number was developed based on the NFs Reynolds ( Re ) number, NPs Reynolds ( Re np ) number, Schmidt ( Sc ) number, and NPs volume fraction with an average relative error percent (REP) of 1.6% and R 2 of 0.99. [ABSTRACT FROM AUTHOR]

Ethylene is the largest base chemical for the chemical industry and produced either by cracking or dehydrogenation of light alkanes. The increasing demand for ethylene has stimulated substantial research into the development of new processes to reduce energy consumption. The ethane dehydrogenation reaction (EDH) using a membrane reactor is an attractive solution because the equilibrium limit can be overcome in favor of ethylene by selective removal of H 2 . The process intensification of EDH reaction was studied in packed-bed membrane reactors (PBMR) operating with a Pt/Al 2 O 3 catalyst. The effects of MFI-type zeolite PBMR and operating conditions on ethane conversion, ethylene selectivity, and ethylene yield were investigated. MFI membrane reactors allowed the equilibrium limit of ethane conversion to be surpassed at high temperatures. It was demonstrated that medium-pore MFI membranes with moderate H 2 /C 2 H 6 selectivity can effectively improve ethane conversion at high operation temperature by timely removal of H 2 through the membranes. The experiment results showed that using MFI zeolite membrane with separation factor of 3.3 for H 2 /C 2 H 6 and H 2 permeance of 1.2 × 10 −7 mol m −2 s −1 Pa −1 at 600 °C helped in enhancing the ethane conversion, ethylene selectivity and ethylene yield from 12%, 86%, and 10% for the packed bed reactor (PBR) to 24%, 90% and 22% for the PBMR respectively. The model calculations have shown that near-completion ethane conversion >98% may be achieved under practically meaningful operating temperature, pressure, and space velocity even for membranes with moderate H 2 selectivity and permeance. [ABSTRACT FROM AUTHOR]

The Kemp elimination reaction is a well-known chemical reaction that is facilitated on a protein surface microenvironment, and in particular is highly accelerated in a unique binding pocket of serum albumin. We have designed and synthesized a fluorescently activatable coumarin derivative with a benzisoxazole scaffold to enable monitoring of the Kemp elimination reaction in terms of fluorescence change for the first time. We show that this fluorescent sensor can sensitively and selectively quantitate serum albumin in blood samples. It also works in a dry-chemistry format. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) are suspected of carcinogenic, neurotoxic and immunotoxic effects in animals and humans. Although background levels of PCBs have been slowly decreased after their ban, they are still among the most persistent and ubiquitous pollutants in the environment, remaining the subject of great concern. PCB 28 is a trichlorinated PCB found in high concentrations not only in human plasma but also in indoor air in Europe, yet little is known about its metabolic pathway and potential metabolites in humans. The present study aims to elucidate the kinetics of metabolite formation and elimination by analyzing four hydroxylated PCBs (OH-PCBs) in human plasma as potential metabolites of the PCB 28 congener. For this purpose, the study was conducted in plasma samples of highly PCB-exposed individuals (N = 268), collected from 2010 to 2014 as a representation of a real case scenario with longitudinal data. OH-PCBs have been predicted, synthesized in the course of this study and further identified and quantitated in human plasma. This is the first time that previously unknown PCB 28 metabolites have been measured in human plasma and half-lives have been estimated for PCB metabolites, which could then provide further understanding in the toxicological consequences of exposure to PCBs in humans. [ABSTRACT FROM AUTHOR]

Many methods used for traffic signal timing are useless if the conditions in the intersection are oversaturated. With an increase in the number of vehicles, the saturation degree approaches or exceeds the limit value at intersections. This creates a scenario where many signal timing methods become overwhelmed. In this paper, the elimination pairing system – a new method for designing traffic signal timing at oversaturated intersections – is expressed. An object function with vehicle delay and stop-start numbers has been generated. Total cost value has been calculated according to the object function. Obtained results were compared with Webster as a traditional traffic signal timing design method and Transyt 14 signal timing software. While Webster gives exaggerated results, Transyt 14 and Elimination Pairing Systems provide better results. As a result of this study, the elimination pairing system could be used for optimizing the traffic signal timings. [ABSTRACT FROM AUTHOR]

The reactions between magnesium or zinc alkyls and 1,8-bis(triorganosilyl)diaminonaphthalenes afford the 1,8-bis(triorganosilyl)diamidonaphthalene complexes with elimination of alkanes. The reaction between 1,8-C10H6(NSiMePh2H)2 and one or two equivalents of MgnBu2 affords two complexes with differing coordination environments for the magnesium; the reaction between 1,8-C10H6(NSiMePh2H)2 and MgnBu2 in a 1 : 1 ratio affords 1,8-C10H6(NSiMePh2)2{Mg(THF)2} (1), which features a single magnesium centre bridging both ligand nitrogen donors, whilst treatment of 1,8-C10H6(NSiR3H)2 (R3 = MePh2, iPr3) with two equivalents of MgnBu2 affords the bimetallic complexes 1,8-C10H6(NSiR3)2{nBuMg(THF)}2 (R3 = MePh22, R3 = iPr33), which feature four-membered Mg2N2 rings. Similarly, 1,8-C10H6(NSiiPr3)2{MeMg(THF)}2 (4) and 1,8-C10H6(NSiMePh2)2{ZnMe}2 (5) are formed through reactions with the proligands and two equivalents of MMe2 (M = Mg, Zn). The reaction between 1,8-C10H6(NSiMePh2H)2 and two equivalents of MeMgX affords the bimetallic complexes 1,8-C10H6(NSiMePh2)2(XMgOEt2)2 (X = Br 6; X = I 7). Very small amounts of [1,8-C10H6(NSiMePh2)2{IMg(OEt2)}]2 (8), formed through the coupling of two diamidonaphthalene ligands at the 4-position with concomitant dearomatisation of one of the naphthyl arene rings, were also isolated from a solution of 7. [ABSTRACT FROM AUTHOR]

BACKGROUND: Chicken meat has the highest per capita consumption among all meat types in North America. The practice of feeding 3-nitro-4-hydroxyphenylarsonic acid (Roxarsone, Rox) to chickens lasted for more than 60 years. However, the fate of Rox and arsenic metabolites remaining in chicken are poorly understood. OBJECTIVES: We aimed to determine the elimination of Rox and metabolites from chickens and quantify the remaining arsenic species in chicken meat, providing necessary information for meaningful exposure assessment. METHODS: We have conducted a 35-day feeding experiment involving 1,600 chickens, of which half were control and the other half were fed a Rox-supplemented diet for the first 28 days and then a Rox-free diet for the final 7 days. We quantified the concentrations of individual arsenic species in the breast meat of 229 chickens. RESULTS: Rox, arsenobetaine, arsenite, monomethylarsonic acid, dimethylarsinic acid, and a new arsenic metabolite, were detected in breast meat from chickens fed Rox. The concentrations of arsenic species, except arsenobetaine, were significantly higher in the Rox-fed than in the control chickens. The half-lives of elimination of these arsenic species were 0.4--1 day. Seven days after termination of Rox feeding, the concentrations of arsenite (3.1 µg/kg), Rox (0.4 µg/kg), and a new arsenic metabolite (0.8 µg/kg) were significantly higher in the Rox-fed chickens than in the control. CONCLUSION: Feeding of Rox to chickens increased the concentrations of five arsenic species in breast meat. Although most arsenic species were excreted rapidly when the feeding of Rox stopped, arsenic species remaining in the Rox-fed chickens were higher than the background levels. [ABSTRACT FROM AUTHOR]

The kinetics of oxidation of glycine, alanine and valine using N-iodosuccinimide in acetic acid-water medium in the presence of hydrochloric acid at 303 K has been studied. The reaction shows inverse first order with respect to oxidant and [H+]. Increase in [amino acid] has a slight positive effect on the rate, indicating first order dependence. Addition of salts like K2SO4, Na2SO4, KCl to the reaction medium has no effect on the rate, increase in temperature increases the rate of the reaction. The amino acids were oxidised to corresponding aldehydes, carbon dioxide, and ammonia. The products obtained were isolated and identified. The activation parameters have been computed. A mechanism confirming to the kinetic observations is suggested. [ABSTRACT FROM AUTHOR]

This paper attempts to discern the physical mechanism of the oxidative desulfurization process simultaneously assisted by ultrasound and phase transfer agent (PTA). With different experimental protocols, an attempt is made to deduce individual beneficial effects of PTA and ultrasound on the oxidative desulfurization system, and also the synergy between the effects of PTA and ultrasound. Effect of PTA is more marked for mechanically stirred system due to mass transfer limitations, while intense emulsification due to ultrasound helps overcome the mass transfer limitations and reduces the extent of enhancement of oxidation by PTA. Despite application of PTA and ultrasound, the intrinsic factors and properties of the reactants such as polarity (and hence partition coefficient) and diffusivity have a crucial effect on the extent of oxidation. The intrinsic reactivity of the oxidant also plays a vital role, as seen from the extent of oxidation achieved with performic acid and peracetic acid. The interfacial transport of oxidant in the form of oxidant–PTA complex reduces the undesired consumption of oxidant by the reducing species formed during transient cavitation in organic medium, which helps effective utilization of oxidant towards desulfurization. [ABSTRACT FROM AUTHOR]

Chiral α-functional lipidic propargylic alcohols extracted from marine sponges, in particular of the pacific genus Petrosia, constitute a class of acetylenic natural products exhibiting remarkable in vitro biological activities, especially anti-tumoral cytotoxicity. These properties, associated to functionalities that are uncommon among natural products, have prompted recent projects on asymmetric total synthesis. On the basis of a three-sector structural typology, three main sub-types of secondary alkynylcarbinols (with either alkyl, alkenyl, or alkynyl as the second substituent) can be identified as the minimal pharmacophoric units. Selected natural products containing these functionalities have been targeted using previously known or on purpose-designed procedures, where the stereo-determining step can be: (i) a C - C bond forming reaction (e.g. the Zn-mediated addition of alkynyl nucleophiles to aldehydes in the presence of chiral aminoalcohols), (ii) a functional layout (e . g . the asymmetric organo- or metallo-catalytic reduction of ynones), or (iii) an enantiomeric resolution (e . g . a lipase-mediated kinetic resolution via acetylation). The promising medicinal importance of these targets is finally surveyed, and future investigation prospects are proposed, such as: (i) further total synthesis of known or future extraction products; (ii) the synthesis of non-natural analogues, with simpler lipophilic environments of the alkynylcarbinol-based pharmacophoric units; (iii) the variation and optimization of both the pharmacophoric units and their lipophilic environment; and (iv) investigations into the biological mode of action of these unique structures. [ABSTRACT FROM AUTHOR]

Highlights: [•] Bioaccumulation of OH-PBDEs in common carp was studied. [•] 2′-OH-BDE68 and 4-OH-BDE90 accumulated to the greatest extent in liver>kidney>muscle. [•] BCFs decreased with the increase of exposure concentration. [•] Relative composition in tissue didn’t change with increasing exposure concentration. [Copyright &y& Elsevier]

The kinetics and mechanisms of thermal decomposition of phenyl acetate andp-tolyl acetate in the gas phase were studied by means of electronic structure calculations using density functional theory methods: B3LYP/6-31G(d,p), B3LYP/6-31++G(d,p), B3PW91/6-31G(d,p), B3PW91/6-31++G(d,p), MPW1PW91/6-31G(d,p), MPW1PW91/6-31++G(d,p), PBE/6-31G(d,p) and PBE/6-31++G(d,p). Two possible mechanisms have been considered: mechanism A is a stepwise process involving electrocyclic [1,5] hydrogen shift to eliminate ketene through concerted six-membered cyclic transition-state structure, followed by tautomerisation of cyclohexadienone or by 4-methyl cyclohexadienone intermediate to give the corresponding phenol. Mechanism B is a one-step concerted [1,3] hydrogen shift through a four-membered cyclic transition-state geometry, to produce ketene and phenol orp-cresol. Theoretical calculations showed reasonable agreement with experimental activation parameters when using the Perdew, Burke and Ernserhof (PBE)functional, through the stepwise [1,5] hydrogen-shift mechanism. For mechanism B, large deviation for the entropy of activation was observed. No experimental data were available forp-tolyl acetate; however, theoretical calculations showed similar results to phenyl acetate, thus supporting the stepwise mechanism for both phenyl acetate andp-tolyl acetate. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Octopus was orally exposed to PSP toxins. [•] Uptake/elimination kinetics were determined. [•] Net accumulation efficiencies up to 42% were calculated. [•] Low rates of depuration and tissue transfer were calculated. [•] Octopus is indicated as high potential vector of PSP toxins. [Copyright &y& Elsevier]

Highlights: [•] Elimination half-life of PFHxA determined from blood of ski wax technicians. [•] Geomean human elimination half-life of PFHxA is 32d (range 14–49d). [•] Elimination half-life of PFHxA in mammalian species is proportional to body weight. [•] Rate of PFHxA elimination from mammals is useful for subsequent risk assessment. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the elimination kinetics of extended therapy with intramammary (IMM) cephapirin in lactating dairy cattle. Eight healthy Holstein-Friesian cows were administered cephapirin (200 mg) into all 4 mammary glands every 24 h after milking. Cows were milked 3 times per day and concentrations of cephapirin and desacetyl cephapirin were determined in bucket milk using liquid chromatography- mass spectrometry. Milk concentration-time data after the last of the 8 IMM infusions were fitted using compartment and noncompartmental models. The maximum cephapirin concentration was 128 ± 57 µg/mL (mean ± SD), the elimination rate constant from the central compartment was 0.278 ± 0.046 (h-1), clearance was 0.053 ± 0.023 L/h, the half time for elimination was 2.55 ± 0.40 h, and the mean residence time was 2.65 ± 0.79 h. The cephapirin concentration was below the approved tolerance in all cows by 96 h after the last infusion, which is the labeled withholding time for the preparation used. Extended therapy for 8 d provided milk cephapirin concentrations above the minimum inhibitory concentration for common grampositive mastitis pathogens (0.1 to 1.0 µg/mL) for the duration of therapy and for an additional 16 to 32 h after the end of treatment. Our findings suggest that this IMM cephapirin sodium formulation, which is labeled for 2 doses 12 h apart, could be administered at a 24-h interval for up to 8 d in cows milked 3 times per day, with no significant effect on residue levels by 96 h after the last treatment. Longer withdrawal times would be prudent for cows with low milk production. [ABSTRACT FROM AUTHOR]

This study reports evidence for catalytic deoxygenation of alkanols, alkanals, and alkanediols on dispersed Cu clusters with minimal use of external H2 and with the concurrent formation of new C-C and C-O bonds. These catalysts selectively remove O-atoms from these oxygenates as CO or CO2 through decarbonylation or decarboxylation routes, respectively, that use C-atoms present within reactants or as H2O using H2 added or formed in situ from CO/H2O mixtures via water-gas shift. Cu catalysts fully convert 1,3-propanediol to equilibrated propanol-propanal intermediates that subsequently form larger oxygenates via aldol-type condensation and esterification routes without detectable involvement of the oxide supports. Propanal-propanol-H2 equilibration is mediated by their chemisorption and interconversion at surfaces via C-H and O-H activation and propoxide intermediates. The kinetic effects of H2, propanal, and propanol pressures on turnover rates, taken together with measured selectivities and the established chemical events for base-catalyzed condensation and esterification reactions, indicate that both reactions involve kinetically relevant bimolecular steps in which propoxide species, acting as the base, abstract the α-hydrogen in adsorbed propanal (condensation) or attack the electrophilic C-atom at its carbonyl group (esterification). These weakly held basic alkoxides render Cu surfaces able to mediate C-C and C-O formation reactions typically catalyzed by basic sites inherent in the catalyst, instead of provided by coadsorbed organic moieties. Turnover rates for condensation and esterification reactions decrease with increasing Cu dispersion, because low-coordination corner and edge atoms prevalent on small clusters stabilize adsorbed intermediates and increase the activation barriers for the bimolecular kinetically relevant steps required for both reactions. [ABSTRACT FROM AUTHOR]

Quaternary ammonium salts with a long hydrocarbon chain are a kind of bifunctional catalysts as the reactions in their presence proceeds by two catalytic pathways, i.e., phase-transfer and a micellar one. The former is inhibited by lipophilic anions such as chlorate etc. The structure-activity relationship for quaternary salts can be described quantitatively using Hansch π-hydrophobicity constants. [ABSTRACT FROM AUTHOR]

The article presents a study on the effect of metal chelation on cadmium kinetics, such as post-exposure phase metal elimination. It states that the study exposed Anodonta anatina L. freshwater clam were exposed to cadmium chloride or the cadmium chloride-disodium ethylenediaminetetraacetic acid (Cd-EDTA) complex. It concludes that metal elimination after dosage discontinuation appeared to proceed in three discernable stages.

The article presents a study which investigates elimination rates of octachlorobiphenyl and hexachlorobiphenyl after dietary exposure. It states that male guppies were fed food contaminated with polychlorinated biphenyls (PCBs). It concludes that residual PCB concentrations will be found which increase with exposure duration.