Stable Degradation Product Research Articles

Effect of nitrogen oxides and sulfur oxides to triphenyl phosphate degradation and cytotoxicity on surface of different transition metal salts

Nitrogen oxides and sulfur oxides, as the dominant toxic gases in the atmosphere, can induce severe human health problems under the composite pollutant conditions. Currently the effect of nitrogen or sulfur oxides in atmospheric environment to the degradation and cytotoxicity of triphenyl phosphate (TPhP) on atmospheric particle surfaces still remain poorly understood. Hence, laboratory simulation methods were used in this study to investigate the effect and related mechanism. First, particle samples were prepared with the TPhP coated on MnSO4, CuSO4, FeSO4 and Fe2(SO4)3 surface. The results showed that, when nitrogen or sulfur oxides were present, more significant TPhP degradation on all samples can be observed under both light and dark conditions. The results proved nitrogen oxides and sulfur oxides were the vital influence factors to the degradation of TPhP, which mainly promoted the OH generation in the polluted atmosphere. The mechanism study indicated that diphenyl hydrogen phosphate (DPhP) and OH-DPhP were two main stable degradation products. These degradation products originated from the phenoxy bond cleavage and hydroxylation of TPhP caused by hydroxyl radicals. In addition, no TPhP related organosulfates (OSs) or organic nitrates (ON) formation were observed. Regarding the cytotoxicity, all the particles can induce more significant cellular injury and apoptosis of A549 cells, which may be relevant to the adsorbed nitrogen oxides or sulfur oxides on particles surfaces. The superfluous reactive oxygen species (ROS) generation was the possible reason of cytotoxicity. This research can supply a comprehensive understanding of the promoting effect of nitrogen and sulfur oxides to TPhP degradation and the composite cytotoxicity of atmospheric particles.

Understanding the behavior of phenylurazole-tyrosine-click electrochemical reaction using hybrid electroanalytical techniques

In this work, the electrochemical behavior of 4-phenylurazole (Ph-Ur) was studied and the latter was used as a molecular anchor for the electrochemical bioconjugation of tyrosine (Y). Cyclic voltammetry (CV) and controlled potential coulometry (CPC) allowed the in-situ generation of the PTAD (4-phenyl-3 H-1,2,4-triazole-3,5(4 H)-dione) species from phenylurazole on demand for tyrosine electrolabeling. The chemoselectivity of the reaction was studied with another amino acid (lysine, Lys) and no changes in Lys were observed. To evaluate the performance of tyrosine electrolabeling, coulometric analyses at controlled potentials were performed on solutions of phenylurazole and the phenylurazole-tyrosine mixture in different proportions (2:1, 1:1, and 1:2). The electrolysis of the phenylurazole-tyrosine mixture in the ratio (1:2) produced a charge of 2.07 C, very close to the theoretical value (1.93 C), with high reaction kinetics, a result obtained here for the first time. The products obtained were identified and characterized by liquid chromatography coupled to high-resolution electrospray ionization mass spectrometry (LC-HRMS and LC- HRMS2). Two products were formed from the click reactions, one of which was the majority. Another part of this work was to study the electrochemical degradation of the molecular anchor 4-phenylazole (Ph-Ur). Four stable degradation products of phenylurazole were identified (C7H9N2O, C6H8N, C6H8NO, C14H13N4O2) based on chromatographic profiles and mass spectrometry results. The charge generated during the electrolysis of phenylurazole (two-electron process) (2.85 C) is inconsistent with the theoretical or calculated charge (1.93 C), indicating that secondary/parasitic reactions occurred during the electrolysis of the latter. In conclusion, the electrochemically promoted click phenylurazole-tyrosine reactions give rise to click products with high reaction kinetics and yields in the (1:2) phenylurazole-tyrosine ratios, and the presence of side reactions is likely to affect the yield of the click phenylurazole-tyrosine reaction.

Evidence for Existence of Multiple Functional Human Small RNAs Derived from Transcripts of Protein-Coding Genes.

The human genome encodes a multitude of different noncoding transcripts that have been traditionally separated on the basis of their lengths into long (>200 nt) or small (<200 nt) noncoding RNAs. The functions, mechanisms of action, and biological relevance of the vast majority of both long and short noncoding transcripts remain unknown. However, according to the functional understanding of the known classes of long and small noncoding RNAs (sncRNAs) that have been shown to play crucial roles in multiple biological processes, it is generally assumed that many unannotated long and small transcripts participate in important cellular functions as well. Nevertheless, direct evidence of functionality is lacking for most noncoding transcripts, especially for sncRNAs that are often dismissed as stable degradation products of longer RNAs. Here, we developed a high-throughput assay to test the functionality of sncRNAs by overexpressing them in human cells. Surprisingly, we found that a significant fraction (>40%) of unannotated sncRNAs appear to have biological relevance. Furthermore, contrary to the expectation, the potentially functional transcripts are not highly abundant and can be derived from protein-coding mRNAs. These results strongly suggest that the small noncoding transcriptome can harbor multiple functional transcripts that warrant future studies.

Is ABA the exogenous vector of interplant drought cuing?

ABSTRACT We have recently demonstrated that root cuing from drought-stressed plants increased the survival time of neighboring plants under drought, which came at performance costs under benign conditions. The involvement of abscisic acid (ABA) was implicated from additional experiments in which interplant drought cuing was greatly diminished in ABA-deficient plants. Here, we tested the hypothesis that ABA is the exogenous vector of interplant drought cuing. Pisum sativum plants were grown in rows of three split-root plants. One of the roots of the first plant was subjected to either drought of benign conditions in one rooting vial, while its other root shared its rooting vial with one of the roots of an unstressed neighbor, which in turn shared its other rooting vial with an additional unstressed neighbor. One hour after subjecting one of the roots of the first plant to drought, ABA concentrations were 106% and 145% higher around its other root and the roots of its unstressed neighbor, compared to their respective unstressed controls; however, the absolute concentrations of ABA found in the rooting media were substantially low. The results may indicate that despite its involvement in interplant drought and the commonly observed exchange of ABA between drought-stressed plants and their rhizospheres, ABA is not directly involved in exogenous interplant drought cuing. However, previous studies have shown that even minute concentrations of ABA in the rhizosphere can prevent ABA leakage from roots and thus to significantly increase endogenous ABA levels. In addition, under drought conditions, plants tend to accumulate ABA, which could markedly increase internal ABA concentrations over time and ABA concentrations in close proximity to the root surface might be significantly greater than estimated from entire rooting volumes. Finally, phaseic acid, an ABA degradation product, is known to activate various ABA receptors, which could enhance plant drought tolerance. It is thus feasible that while the role of ABA is limited, its more stable degradation products could play a significant role in interplant drought cuing. Our preliminary findings call for an extensive investigation into the identity and modes of operation of the exogenous vectors of interplant drought cuing.

A large geographic-scale characterization of organochlorine pesticides (OCPs) in surface sediments and multiple aquatic foods of inland freshwater aquaculture ponds in China: Co-occurrence, source and risk assessment

Inland freshwater aquaculture ponds (IFAPs) represent the key component of the global lentic freshwater environment and are increasingly important for global aquaculture production, yet the occurrence of organochlorine pesticides (OCPs) in these pond systems remains largely unknown. Here, we characterized the residual concentrations of 19 individual OCPs in sediments and in cultured fish and crustacean species (crabs, shrimp, crayfish and lobster), which were on-spot sampled from the IFAPs at a large region-scale in China. The total OCP levels in sediments varied dramatically between regions. Crabs presented the greatest OCP contamination among the studied species. Dichlorodiphenyltrichloroethanes (DDTs) was the dominating contaminant in sediments and crabs and its stable degradation products 4,4′-DDE and 4,4′-DDD were co-occurrent between these two compartments. The diagnostic ratio analysis indicated fresh inputs of DDTs, lindane and aldrin in multiple regions, which may be resulted from agricultural soil erosion, surface runoff and local anthropogenic activities. Ecological impacts of these pesticides could be expected at some sites due to their levels in sediments above the risk level. Risk assessment based on the OCP levels corrected by the cooking loss revealed that daily consumption of the IFAPs-derived aquatic foods may pose carcinogenic risks in humans.

Removal of hydrochlorothiazide from drinking and environmental water: Hydrolysis, direct and indirect photolysis

Diuretic hydrochlorothiazide (HCTZ) has been detected in drinking and environmental water. Since HCTZ exhibited some toxic effects on the environment, it is essential to propose safe and economical ways of its removal. The influence of water quality on the removal efficiency of HCTZ from the environment was observed. The stability of HCTZ was investigated in ultrapure (UPW), tap, and two different environmental waters, by hydrolysis, photolysis, and indirect photolysis under simulated solar irradiation (SSI) and UV irradiation. Also, experiments were conducted at temperatures of (5 ± 1) °C and (25 ± 1) °C, in the dark. Comprehensive experimental and computational analysis was performed to examine the stability and reactivity. The results show that HCTZ is susceptible to hydrolysis. Photolysis and indirect photolysis were efficient under UV irradiation, wherein HCTZ was entirely degraded after 180 min of irradiation in UPW. Chloride ions, carbonates, calcium, and magnesium ions present in natural waters inhibited the degradation of HCTZ. This diuretic has significant interaction with •OH radicals. A 4-amino-6-chlorobenzene-1,3- disulfonamide (ABSA) was observed as a stable degradation product, and ABSA formation's degradation mechanism was proposed. Mineralization of HCTZ was above 50% in H2O2/UV system in UPW after 180 min of irradiation.

Modeling the Formation of Degradation Compounds during Thermal Degradation of MEA

A kinetic model has been developed to predict thermal degradation of aqueous solutions of monoethanolamine (MEA) in carbon capture. The model focusses on both the degradation rate of the amine and the formation rates of selected degradation products as a function of time, temperature, and loading. Experimental literature data on thermal degradation of MEA were used to develop, fit, and evaluate the model. The model was found to have an average relative deviation of 17.5%, most of which was caused by uncertainty in experimental data. The degradation model was also compared to a cyclic degradation campaign. The concentration of 1-(2-hydroxyethyl)-2-imidazolidinone (HEIA), one of the more stable thermal degradation products, is well-predicted with the thermal degradation model. However, the results also indicate that oxidative and thermal degradation mechanisms interact and that this interaction influences the concentration of several thermal degradation products.

Nitric Oxide Mediation in Hydroxyurea and Nitric Oxide Metabolites' Inhibition of Erythroid Progenitor Growth.

In several systems, hydroxyurea has been shown to trigger nitric oxide (NO) release or activation of NO synthase (NOS). To elucidate this duality in its pharmacological effects, during myelosuppression, we individually examined hydroxyurea’s (NO releasing agent) and NO metabolites’ (stable NO degradation products) effects on erythroid colony growth and NOS/NO levels in mice using NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). Hydroxyurea and nitrite/nitrate decreased the bone marrow cellularity that was blocked by PTIO only for the NO metabolites. Hydroxyurea inhibition of colony-forming unit-erythroid (CFU-E) formation and reticulocytes was reversed by PTIO. Moreover, hydroxyurea, through a negative feedback mechanism, reduced inducible NOS (iNOS) expressing cells in CFU-E, also prevented by PTIO. Nitrate inhibition of burst-forming units-erythroid (BFU-E) colony growth was blocked by PTIO, but not in mature CFU-E. The presented results reveal that NO release and/or production mediates the hydroxyurea inhibition of mature erythroid colony growth and the frequency of iNOS immunoreactive CFU-E.

2-ЭТИЛТИОБЕНЗИМИДАЗОЛА ГИДРОБРОМИД ПРЕДУПРЕЖДАЕТ СНИЖЕНИЕ ТОНУСА КОРОНАРНЫХ СОСУДОВ И СОКРАТИТЕЛЬНОЙ СПОСОБНОСТИ МИОКАРДА У КРЫС ПРИ ЭКСПЕРИМЕНТАЛЬНОМ САХАРНОМ ДИАБЕТЕ

Objectives. To assess the possibility of preventing the disturbances of coronary vascular tone and myocardial contractile function caused by diabetes mellitus with the help of 2-ethylthiobenzimidazole hydrobromide. Material and methods. Coronary vascular tone and myocardial contractile function were studied on preparations of rat hearts isolated by the Langendorff method. The iNOS blockade was carried out with S-methylisothiourea (S-MT, 10&lt;sup&gt;-6&lt;/sup&gt;M). Diabetes mellitus in rats was modelled by means of a single intraperitoneal injection of streptozocin (50 mg / kg). 2-ethylthiobenzimidazole hydrobromide (2-ETG) was injected intraperitoneally at a dose of 3 mg / kg. The concentration of stable degradation products of NO (NO&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;/NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;), superoxide dismutase, catalase, diene conjugates and malondialdehyde in the left ventricular homogenate was determined by spectrophotometric method. The content of inducible and endothelial NO-synthases (eNOS), interleukin 1β, C-reactive protein in the blood serum of experimental animals was determined by enzyme immunoassay. Results. In the hearts of «2-ETG + Diabetes mellitus» animal group no changes in the coronary perfusion pressure and developed intraventricular pressure were observed before and after the use of the highly selective iNOS blocker S-methylisothiourea. In the blood serum of these animals group, an increase in the concentration of eNOS was observed, against the background of a decrease in the accumulation of iNOS, a decrease in the concentration of lipid peroxidation products was determined against the background of an increase in the activity of the antioxidant system and a decrease of systemic inflammation. Conclusions. Intraperitoneal injection of 2-ethylthiobenzimidazole hydrobromide prevents a decrease in coronary vascular tone and myocardial contractile function caused by hyperproduction of nitrogen monoxide of inducible NO-synthase in diabetes mellitus. This effect of 2-ethylthiobenzimidazole hydrobromide is associated with: limiting the formation of oxidative stress; limiting the nitrosative stress; the decrease in the concentration of inflammatory markers.

Original Method for Evaluating Endothelial Vasomotor Function of Isolated Vessel in Experiment.

We describe a method for experimental assessment of endothelial dysfunction in an isolated using extracorporeal machine perfusion and vasoactive substrates agents (norepinephrine and acetylcholine). Quantitative assessment of endothelial vasomotor dysfunction was proposed, based on registration of changes in volumetric perfusate flow rate through the isolated vessel. Functional activity of the isolated aorta endothelium and total content of stable NO degradation products in blood plasma were studied in outbred white male rats after subtotal liver resection. Impaired vasodilation ability of the aorta and increased content of NO degradation products in blood plasma observed after surgery indicate the development of vasomotor endothelial dysfunction associated with oxidative stress, cholemia, and endotoxemia.

Oxidative and Nitrosative Stress in Oral Squamous Cell Carcinoma

Introduction: The incidence of oral squamous cell carcinoma (OSCC) shows a constant increase, while the long-term outcome remains poor over the last decades. Radical oxygen and nitrogen species (RONS) – initially released by carcinogens, such as alcohol and tobacco, and later maintained by the tumor microenvironment – appear to be strongly associated to chronic inflammation, tumor induction, progression, and metastatic spread. The aim of this study was to evaluate the role of oxidative and nitrosative stress in primary OSCC compared to healthy tissue specimens and to identify their impact on tumor carcinogenesis. Materials and Methods: In this basic research study, tissue samples of 30 patients with primary OSCC were evaluated for the expression of pAKT, pERK, 3-NT, NOS1, NOS3, MAPK1, and IP-8 by immunohistochemistry and RT-PCR and compared to those of a healthy control group (n = 30). Results: The results showed a significantly increased expression of pAKT (p < 0.001), pERK (p = 0.01), 3-NT (p = 0.039), NOS1 (p = 0.025), NOS3 (p = 0.046), and MAPK1 (p = 0.032) in OSCC tissue samples compared to healthy controls. Conclusion: The results of this study prove the tested stable degradation products to be suitable for the detection of RONS in OSCC. Moreover, the significantly increased expression underlines the role of RONS in carcinogenesis of OSCC, suggests specific mechanisms of detection, and anticipates supplementary research.

Cytotoxicity of nonylphenol on spermatogonial stem cells via phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin pathway.

With continuous advancement of industrial society, environmental pollution has become more and more serious. There has been an increase in infertility caused by environmental factors. Nonylphenol (NP) is a stable degradation product widely used in daily life and production and has been proven to affect male fertility. However, the underlying mechanisms therein are unclear. Thus, it is necessary to study the effect and mechanism of NP on spermatogonial stem cells (SSCs). To investigate the cytotoxic effect of NP on SSCs via the phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway. SSCs were treated with NP at 0, 10, 20 or 30 µmol. MTT assay was performed to evaluate the effect of NP on the proliferation of SSCs. Flow cytometry was conducted to measure SSC apoptosis. The expression of Bad, Bcl-2, cytochrome-c, pro-Caspase 9, SOX-2, OCT-4, Nanog, Nanos3, Stra8, Scp3, GFRα1, CD90, VASA, Nanos2, KIT, PLZF and PI3K/AKT/mTOR-related proteins was observed by western blot, and the mRNA expression of SOX-2, OCT-4 and Nanog was detected by quantitative reverse transcription polymerase chain reaction. Compared with untreated cells (0 μmol NP), SSCs treated with NP at all concentrations showed a decrease in cell proliferation and expression of Bcl-2, Nanog, OCT-4, SOX-2, Nanos3, Stra8, Scp3, GFRα1, CD90, VASA, Nanos2, KIT, and PLZF (P < 0.05), whereas the expression of Bad, cytochrome-c, and pro-Caspase 9 increased significantly (P < 0.05). We further examined the PI3K/AKT/mTOR pathway and found that the phosphorylation of PI3K, AKT, mTORC1, and S6K was significantly decreased by NP at all concentrations compared to that in untreated SSCs (P < 0.05). NP exerted the greatest effect at 30 μmol among all NP concentrations. NP attenuated the proliferation, differentiation and stemness maintenance of SSCs while promoting apoptosis and oxidative stress. The associated mechanism may be related to the PI3K/AKT/mTOR pathway.

Computational Study of Photo-oxidative Degradation Mechanisms of Boron-Containing Oligothiophenes.

We have modeled possible photo-oxidative degradation pathways for a set of boron-containing oligothiophenes, which have potential use in organic electronic devices. Photogenerated reactive oxygen species such as hydroxyl radical, hydroperoxyl radical, and singlet and triplet molecular oxygen are taken into account in three main pathways, namely, sulfoxide formation, sequential addition, and stepwise singlet molecular oxygen addition. Density functional theory at the B3LYP level is used to assess the reaction kinetics and thermodynamics. Our findings show that the influence of the number of thiophene rings and the presence of boron is in most cases minor in terms of degradation. The formation of sulfoxide on the thiophene ring is among the easiest degradation pathways if hydroxyl radical is present in the system. The hydroxyl radical attack on the Cβ of thiophene ring of BMBE-1T (2,5-bis(E-dimesitylborylethenyl)thiophene) forms the BMBE-1T(C)OH radical adduct which is kinetically and thermodynamically more favorable than the hydroperoxyl radical attack. The stepwise triplet molecular oxygen addition on the BMBE-1T(C)OH radical adduct has a free energy barrier around 19 kcal·mol-1, and it results in thermodynamically stable degradation product via ring cleavage. Stepwise reactions with singlet molecular oxygen have energy barriers of roughly 40 kcal·mol-1. Singlet molecular oxygen attack on the α-carbon of the thiophene ring is kinetically much more favored than the attack on the beta carbon. Our results elucidate the preferred degradation mechanism of the thiophene backbone of the selected photoactive oligomers. Moreover, the findings of this theoretical study clarify the photostability, and hence the potential drawbacks, of the large-scale use of this class of polythiophenes.

Occurrence and partitioning of antifouling booster biocides in sediments and porewaters from Brazilian Northeast

Fouling organisms attach and grow on submerged surfaces causing several economic losses. Thus, biocides have been introduced in antifouling paints in order to avoid this phenomenon, but their widespread use became a global problem, mainly in ports, leisure and fishing boat harbors, since these substances can be highly toxic to non-target organisms. The occurrence and environmental behavior of antifouling biocides are especially unknown in some peculiar regions, such as Amazon areas. Thus, the aim of this work was to evaluate, for the first time, levels and the partitioning behavior of the antifouling organic biocides irgarol, diuron and also stable degradation products of dichlofluanid and diuron (DMSA and DCPMU, respectively) in sediments and porewaters from a high boat traffic area located in the Northeast of Brazil, a pre-Amazon region. Our results showed high concentrations of irgarol (<1.0–89.7 μg kg−1) and diuron (<5.0–55.2 μg kg−1) in sediments. In porewater, DCPMU (<0.03–0.67 μg L−1) and DMSA (<0.008–0.263 μg L−1) were the mainly substances detected. High Kd and Koc obtained for both irgarol and diuron showed a partitioning preference in the solid phase. This work represents one of the few registers of contamination by antifouling substances in Amazonian areas, despite their environmental relevance.

The effects of hepatic steatosis on thromboxane A2 induced portal hypertension

Introduction and aimThromboxane (TX) A2 was identified as an important vasoconstrictor during Zymosan induced portal perfusion pressure (PP) increase. We aimed at investigating whether hepatic steatosis influences the extent of TXA2-induced portal hypertension. Materials and methodsSprague–Dawley rats were randomly divided into control and steatosis (induced by the special diet) groups. PP and TXB2 (stable degradation product of TXA2) in the perfusate were measured after in situ liver perfusion with Zymosan (150μg/ml, 40–46min) or U46619 (TXA2 analog, 0.1μM/ml, 40–46min). The number of Kupffer cell (KC) was measured by immunohistochemistry with CD163. ResultsZymosan induced more TXB2 production and a higher PP increase in control group than in steatosis group despite more CD163 positive KCs in fatty livers. PP and TXB2 efflux revealed a strong correlation in control group and a moderate correlation in steatosis group. Contrary to the effect of Zymosan, U46619 induced a much higher PP increase in steatosis group than in control group. ConclusionSevere steatosis increased number of KCs, however, PP increase and TXB2 efflux caused by Zymosan infusion in fatty livers were lower than those in healthy livers. In contrast, TXA2 analog caused higher PP increase in fatty livers. Targeting the more sensitive response to TXA2 in fatty livers might be a potential therapy of severe steatosis.

Quantification and Simulation of Thermal Decomposition Reactions of Li-Ion Battery Materials By Simultaneous Thermal Analysis Coupled with Gas Analysis

Internal short-circuit is one of the major safety hazards in lithium-ion battery systems, possibly leading to single cell thermal runaway (TR) and propagation to neighbouring cells. Therefore, developing tests to assess safety properties of batteries is essential to prevent potential safety hazards to the users. The main goal of this work is to understand the thermal effects of the most important parameters for triggering thermal runaway, induced by internal short-circuit, in a Graphite-Lithium Nickel-Manganese-Cobalt-Oxide (NMC 111) battery cells. This investigation will allow the reduction of parameters to the most significant ones on the tests outcome, reducing the number of test needs. The first part of this work, presented here, aims at the identification of the main decomposition processes, using Differential Scanning Calorimetry (DSC) and Thermal Gravimetry (TGA) combined with gas analysis (FTIR and GC-MS) and the subsequent development of reaction kinetics model. The activation energy, frequency factor and heat of reaction of the different sub-processes taking place in a thermal event are calculated using 3 different heating rates: 5, 10 and 15ºKmin-1. It is found that both the anode and cathode thermally decompose in multiple parallel and consecutive reactions between 100-600 ºC. A double breakdown mechanism of the SEI layer is suggested to describe the anode thermal decomposition profile. The experimental data show a partial breakdown of the primary SEI layer along with secondary SEI formation. With increasing temperature, a second breakdown occurs with decomposition of the organic/polymeric part from the secondary SEI layer, leading to the full consumption of intercalated Li. Processes like EC (ethylene carbonate) evaporation with simultaneous EC decomposition and Li-electrolyte reactions have been identified. In a third phase, the binder and the more stable degradation products decompose. A combination of diffusion-type kinetic and Arrhenius-type kinetic with Kissinger analysis has been suggested to model the anode decomposition profile. With respect to the cathode decomposition, the following processes have been identified: EC evaporation, NMC(111) decomposition with release of oxygen and combustion of EC. At a later stage, the decomposition of binder and combustion of conductive carbon additive with the evolved oxygen from NMC decomposition have been observed. The thermal decomposition profile of cathode has been described using Arrhenius-type kinetic and Kissinger analysis. The simulated heat flow curves for both electrodes show good agreement with experimental ones. In particular for the anode, the simulated double breakdown mechanism of the SEI layer fits better the experimental curve than the single breakdown mechanism, in agreement with the literature. The simulated cathode curve shows a good fit with the experimental one when taking into account the electrolyte. From the thermal data and measurement uncertainties, an approximate kinetic model is developed to simulate the dynamic of a thermal runaway in a realistic way. The second part of this work (not shown here) is to simulate TR and to calculate the probability of thermal runaway as a function of the parameters of a triggering method.

Solvent extraction based reclaiming technique for the removal of heat stable salts (HSS) and neutral degradation products from amines used during the capture of carbon dioxide (CO2) from industrial flue gases

This work used a modified OH-aliquat mixed with a new diluent, namely, 2-ethyl-1-hexanol to separate heat stable salts (HSS), namely, formate, glycolate and oxalate as well as neutral degradation products (i.e. imidazole, N-acethylethanolamine, 2-oxazolidone, N-(2-hydroxyethyl)-succinimide) from monoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP), and N-methyldiethanolamine (MDEA) and their blends which are amines/amine blends typically used for carbon dioxide (CO2) capture from industrial flue gases. The new diluent, which has a branched-chain structure, increased the extraction performance of the OH-aliquat up to 50% HSS removal from MEA solution compared to our previous straight-chained 1-octanol diluent. The extractant also performed very well in removing HSS from MDEA and AMP with the ease of HSS extraction increasing in the order of AMP < MEA < MDEA for which the oxalate was removed by nearly 100% regardless of the type of amine and concentration. In blended MEA, AMP and MDEA, the extractant had a higher chemical affinity in removing all HSS when compared with single MEA. The extractant could also remove major neutral degradation products found in MEA solution. High temperature and low CO2 loading conditions were found to be favorable in maximizing the ability of the extractant to remove both product types. This finding revealed that the exact location where the amine slipstream should be taken for simultaneous extraction of all degradation products is at the exit point of the lean-rich amine heat exchanger. The regeneration of extractant using sodium hydroxide solution (NaOH) also indicated the reusability of the extractant as long as its reactive molecules remained. The results obtained from this study are being used for further development of the extraction process that can be used as a permanent replacement for conventional reclaiming techniques.

Polybrominated Diphenylethers (PBDEs) in ambient air samples at the electronic waste (e-waste) reclamation site.

Polybrominated Diphenylethers (PBDEs) were used as flame-retardants in various building materials, plastic and other polymers, airplanes, electronics etc. All or some of their congeners have been already banned in many countries, due to their persistency and adverse health effects. In this study, we are focusing on the e-wastes as a source of emission of PBDEs in ambient air during reclamation processes. The ambient air particulate matter (PM) samples were collected at and near e-waste reclamation site in Bangkok, Thailand. Results showed the presence of various homologues viz: tri, tetra, penta, hexa, and hepta-PBDEs on both PM2.5 and Total Suspended Particle (TSP) samples. The comparison of samples as a function of distance from reclamation site indicated elevated levels of PBDEs in the close proximity to e-waste site. Interestingly, a shift in the congener pattern was observed with lower brominated PBDEs being more prevalent on nearby off-site samples as compared to the PM collected at the e-waste site. The total penta-PBDEs concentration is about double on e-waste site PM2.5 compared to control site samples. For TSP, tetra, penta, and hepta-PBDEs congeners are at higher concentrations at e-waste sites and its vicinity compared to reference sites. Overall, a clear trend can be observed indicating a debromination of PBDEs to more toxic tri and tetra congeners during reclamation process and PBDEs are being translocated from treated materials to ambient air PM. BDE 30 congener is identified as a specific marker of thermal reclamation processes of e-wastes as a most stable degradation product. This work indicates potential hazards related to the reclamation of e-wastes and remediation of sites containing PBDEs. In particular, thermal treatment methods can lead to congener transformation and increased emissions of more toxic lower-brominated congeners.

Bacteriohopanepolyols across environmental gradients in Lake Vanda, Antarctica.

Bacteriohopanepolyols (BHPs) are bacterial membrane lipids that may be used as biological or environmental biomarkers. Previous studies have described the diversity, distribution, and abundance of BHPs in a variety of modern environments. However, the regulation of BHP production in polar settings is not well understood. Benthic microbial mats from ice-covered lakes of the McMurdo Dry Valleys, Antarctica provide an opportunity to investigate the sources, physiological roles, and preservation of BHPs in high-latitude environments. Lake Vanda is one of the most stable lakes on Earth, with microbial communities occupying specific niches along environmental gradients. We describe the influence of mat morphology and local environmental conditions on the diversity and distribution of BHPs and their biological sources in benthic microbial mats from Lake Vanda. The abundance and diversity of C-2 methylated hopanoids (2-MeBHP) are of particular interest, given that their stable degradation products, 2-methylhopanes, are among the oldest and most prevalent taxonomically informative biomarkers preserved in sedimentary rocks. Furthermore, the interpretation of sedimentary 2-methylhopanes is of great interest to the geobiology community. We identify cyanobacteria as the sole source of 2-MeBHP in benthic microbial mats from Lake Vanda and assess the hypothesis that 2-MeBHP are regulated in response to a particular environmental variable, namely solar irradiance.

Optimization of a microchip electrophoresis method with electrochemical detection for the determination of nitrite in macrophage cells as an indicator of nitric oxide production.

Nitric oxide (NO) is involved in many biological functions, including blood pressure regulation, the immune response, and neurotransmission. However, excess production of NO can lead to the generation of reactive nitrogen species and nitrosative stress and has been linked to several neurodegenerative diseases and cardiovascular disorders. Because NO is short-lived and generally difficult to detect, its primary stable degradation product, nitrite, is frequently monitored in its place. In this paper, an improved method using microchip electrophoresis with electrochemical detection (ME-EC) was developed for the separation and detection of nitrite in cell lysates. A separation of nitrite from several electroactive cell constituents and interferences was optimized, and the effect of sample and buffer conductivity on peak efficiency was explored. It was found that the addition of 10 mM NaCl to the run buffer caused stacking of the nitrite peak and improved limits of detection. A platinum black working electrode was also evaluated for the detection of nitrite and other electroactive cellular species after electrophoretic separation. The use of a modified platinum working electrode resulted in 2.5-, 1.7-, and 7.2-fold signal enhancement for nitrite, ascorbic acid, and hydrogen peroxide, respectively, and increased the sensitivity of the method for nitrite twofold. The optimized ME-EC method was used to compare nitrite production by native and lipopolysaccharide-stimulated RAW 264.7 macrophage cells.