Diethyldithiocarbamic Acid Research Articles

Extraction and enrichment of lead from contaminated soil using chelation reactions

Heavy metals such as lead (Pb) are significantly harmful to human health and may have disastrous effects on the ecosystem. Consequently, Pb-contaminated soil necessitates remediation to bring Pb levels below the standard threshold of 150 mg/kg. This study aimed to devise processes for extracting and enriching Pb using chelation reactions. Pb was effectively extracted from the soil using EDTA as the chelating agent, forming a complex ([Pb-HEDTA]-) that is solubilized in the solution. Extraction efficiency increased with higher EDTA/Pb molar ratios, remaining relatively constant at 100 or above. Elevated temperatures also enhanced Pb extraction; concentrations below 150 mg/kg were achieved at 25 °C or higher. The desorption of Pb followed the Langmuir equation, indicating uniform one-to-one Pb desorption. The addition of the chelating flocculant diethyldithiocarbamic acid (DDTC) concentrated Pb in the solid phase, reducing sludge volume. Pb transfer rate rose with increasing DDTC/[Pb-EDTA]2− ratio, peaking at 90 % with a ratio of 50. The presence and extraction of other elements (Fe, Cu, and Zn) did not impede Pb extraction and enrichment. Therefore, this study and its findings could provide the basis for further development of the Pb extraction process and mitigate the problem of Pb-contaminated soil when designing Pb extraction plants.

Exogenous methyl jasmonate promotes wound healing of Chinese yam tubers (Dioscorea opposita) through the deposition of suberin polyaliphatics at the wound sites

Suberin polyaliphatics (SPA) is an important component of suberin, which plays a pivotal role in controlling water loss and solute fluxes during wound healing of fruit and vegetables. The objective of this study was to investigate the effect of exogenous methyl jasmonate (MeJA) on wound-induced SPA deposition in Chinese yam tubers. The results exhibited that MeJA treatment accelerated the deposition of SPA and the wound healing process. The gene expressions of β-ketoacyl-CoA synthases (DoKCS2, DoKCS6), CYP86 subfamily of cytochrome P450 monooxygenases (DoCYP86A1, DoCYP86B1) and Glycerol-3-phosphate acyltransferases (DoGPAT5, DoGPAT7) and their corresponding protein content (i.e. KCS, CYP, GPAT) associated with SPA monomer biosynthesis were notably increased by MeJA application. Meanwhile, MeJA also enhanced gene expressions of ATP-binding cassette transporter subfamily G proteins (DoABCG2, DoABCG6) and GDSL-type esterase/lipases (DoGELP38, DoGELP51, DoGELP96) and increased ABCG content, which might participate in the trafficking and polymerization of SPA monomer. Noteworthily, application of diethyldithiocarbamic acid (DICA), an inhibitor of jasmonic acid (JA) synthesis, showed an opposite effect to MeJA treatment. These results suggest that MeJA could promote SPA deposition by positively regulating relevant gene expression and corresponding protein content, thereby accelerating wound healing of Chinese yam tubers.

Speciation analysis of inorganic arsenic in water samples using thiol-ligand and cotton fibres followed by ICP-OES determination

ABSTRACT This research aimed to develop a method for the speciation analysis of arsenic species, including As(III) and As(V) in environmental samples. Cotton fibres and thiol-ligands, including ammonium pyrrolidine dithiocarbamate (APDC), L-cysteine, and diethyldithiocarbamic acid (DDTC), were used as a simple solid phase extraction (SPE) followed by arsenic determination using inductively coupled plasma optical emission spectrometry (ICP-OES). The separation parameters were thoroughly investigated, including pH, thiol-ligand concentration, cotton fibre amount, type of eluents, and flow rate. It was found that As(III) could be efficiently separated from As(V) by using a column containing 0.5 g cotton fibres and 0.1% APDC under pH 2. As(III) was then eluted using 5 mL of mixed solvents of 4 M HNO3, 4 M HCl, and 0.5 M H2O2 (1:1:1 v/v). The method was then used to perform a speciation analysis of arsenic in model solutions with As(III) and As(V) concentrations ranging from 10–1000 μg/L. The results showed good recoveries of both arsenic species at 80–120% with a satisfactory percentage relative standard deviation (%RSD). The developed method was subsequently applied for arsenic speciation analysis in the environmental samples, including natural and wastewater samples.

Methyl jasmonate facilitates wound healing of Chinese yam tubers via positively regulating the biosynthesis and polymerization of suberin polyphenolics

Suberin is a cell wall-associated heteropolymer composed of suberin polyaliphatics (SPA) and suberin polyphenolics (SPP), which confers a hydrophobic barrier to plants against dehydration and pathogen invasion. Jasmonic acid (JA) plays a positive role in wound-induced SPP deposition in kiwifruit and potato tubers, but the mechanism underlying the regulation of JA on wound healing of Chinese yam tubers remains unknown. In this study, the biochemical and physiological responses to methyl jasmonate (MeJA) and diethyldithiocarbamic acid (DIECA, an inhibitor of JA biosynthesis) treatments in wound yam tubers were investigated. The results showed that exogenous MeJA promoted the production of endogenous JA with increased gene expressions of lipoxygenase (LOX) and 12-oxo-phytodienoic acid reductase (OPR) in wound tubers. The activities and gene expressions of phenylalanine ammonialyase (PAL), cinnamic acid 4-hydroxylase (C4H) and 4-coumarate-CoA ligase (4CL) in wound tubers were pronouncedly enhanced by MeJA, along with increase of SPP monomers, especially, hydroxycinnamic acids (HAs). Meanwhile, MeJA increased the activities and gene expressions of peroxidase (POD), NADPH oxidase (NOX), polyamine oxidase (PAO), and the generation of hydrogen peroxide (H2O2), which were likely to be involved in the polymerization of SPP monomers resulting in SPP deposition. Conversely, inhibition of JA biosynthesis by DIECA reversed the positive impact of MeJA on wound healing process. The results indicate that rapid wound healing in Chinese yam tubers could be induced by MeJA via stimulating phenylpropanoid metabolism, POD activity and H2O2 generation involved in SPP deposition.

Chelator Iminodisuccinic Acid Regulates Reactive Oxygen Species Accumulation and Improves Maize (Zea mays L.) Seed Germination under Pb Stress

To explore the effects of iminodisuccinic acid (a chelating agent) on maize (Zea mays L.) seed germination under lead (Pb) stress, we comparatively analyzed the effects of applying different concentrations of iminodisuccinic acid (0, 5, 20, and 100 mmol·dm−3) and combined an addition of exogenous substances regulating reactive oxygen species production on maize seed germination, seedling growth, H2O2 content, NADPH oxidase activity, and antioxidant enzyme activities under Pb-stressed and Pb-free conditions. Iminodisuccinic acid (100 mmol·dm−3) significantly delayed seed germination under normal germination conditions and alleviated the inhibitory effects of Pb stress (20 mmol·dm−3) on seed germination. Under normal conditions (without Pb stress), the iminodisuccinic acid-induced inhibition of seed germination was enhanced by treatment with dimethylthiourea (a specific scavenger of reactive oxygen species) or diphenyleneiodonium chloride (a specific inhibitor of NADPH oxidase), but diminished by treatment with H2O2, CaCl2, diethyldithiocarbamic acid (a specific inhibitor of superoxide dismutase), or aminotriazole (a specific inhibitor of catalase). Under Pb stress, iminodisuccinic acid partially eliminated the excessive H2O2 accumulation, improved superoxide dismutase and catalase activity, and weakened the high NADPH oxidase activity. In addition, Ca2+ chelation may be essential for maintaining the reactive oxygen species’ balance and improving seed germination and seedling growth by iminodisuccinic acid supplementation in maize under Pb stress. The proposed iminodisuccinic acid supplementation-based method improved maize seed germination in Pb-polluted soil.

The Comparison of the Parameters Antioxidant Activity of Ginger (Zingiber officinale Roscoe) and Commercial Antioxidants

The study was aimed at evaluating the antioxidant activity of Zingiber officinale Roscoe (ginger) extract compared to antioxidant compounds such as; Butyl Hydroxy toluene (BHT), Diethyl-dithiocarbamate (DDC) and Ascorbic Acid (Vit. C). The antioxidant activity (DPPH), total phenolic content (TPC) and reducing power (RP) were studied. DPPH inhibitory values demonstrated through IC50 from ginger extract were significantly lower than those of other antioxidants at the same concentrations: ginger (122.2 ± 16.78%), Vit. C (158.21 ± 4.14%), BHT (195.84 ± 5.94%) and DDC (240.39 ± 43.75%) respectively. This proves that ginger extract is more active inhibiting DPPH free radicals. At a concentration of 100 μg / ml, the TPC level indicates the order: Vit. C > DDC > BHT > ginger respectively. As for RP test at concentration 100 μg / ml also Vit. C > ginger > DDC > BHT respectively. The results obtained in present study indicate that, ginger extract is a potential source of natural antioxidant capable of inhibiting and breaking the free radical chain and it’s expected to suppress the development of degenerative cells diseases.

Synergetic surface defect passivation towards efficient and stable inorganic perovskite solar cells

Metal halide inorganic perovskites with excellent thermal stability are holding promise for practical application of perovskite solar cells (PSCs). However, ionic defects, especially iodine vacancies or undercoordinated lead, from the perovskite film surface restrain the obtainment of maximum open circuit voltage as well as long term stability of devices. In this regard, reducing the detrimental defects is of priority to further enhance the performance of inorganic PSCs. Herein, we employed an organic amine compound, specifically diethyldithiocarbamic acid diethylamine (DADA), to passivate the ionic defects on the surface of CsPbIxBr3-x inorganic perovskite film. It is found that the electron-rich sulfur atoms from DADA molecule react with undercoordinated Pb in perovskite, while diethylamine cation effectively forms hydrogen bond with halide ion, further strengthening the passivation effect. Such synergetic passivation, together with the improved film morphology, significantly reduces the defect density and prolongs the lifetime of charge carriers within the perovskite film. Moreover, DADA treatment induces an upward shift of the energy band edge of the perovskite layer, which may facilitate hole extraction at the interface. These combination raises the solar cell efficiency from 18.56% to 20.06% under 100 mW cm−2 illumination. More importantly, the mitigation of ionic defects via DADA passivation dramatically improve the devices ambient stability by retaining the PCE of nearly 90% over 800 h in a 30–40% relative humidity environment.

AchMYC2 promotes JA-mediated suberin polyphenolic accumulation via the activation of phenylpropanoid metabolism-related genes in the wound healing of kiwifruit (Actinidia chinensis)

Suberin polyphenolic (SPP), a kind of agronomically significant biopolymer, is composed primarily of phenolic acids generally synthesized by phenylpropanoid metabolism. In this study, the transcriptional activation of suberin polyphenolic biosynthesis by jasmonic acid (JA) inducible-transcription factor AchMYC2 was confirmed in wound tissues of kiwifruit (Actinidia chinensis). Three general phenylpropanoid metabolism-related genes, AchPAL, AchC4H and Ach4CL respectively encoding phenylalanine ammonia-lyase (PAL), cinnamic acid-4-hydroxylase (C4H) and 4-coumaric-CoA ligase were determined in the kiwifruit core tissues overexpressing these genes. Besides, the positive regulation of AchMYC2 on AchPAL, AchC4H and Ach4CL was observed. JA-induced AchMYC2 locating in the nucleus activated the transcriptional expression of AchPAL, AchC4H and Ach4CL through binding to their promoters. The results were further evidenced in the kiwifruit core tissues overexpressing of AchMYC2, in which AchMYC2 enhanced the expression levels of AchPAL, AchC4H and Ach4CL and increased the accumulation of phenolic acids including cinnamic acid, p-coumaric acid, caffeic acid, ferulic acid and sinapic acid. Meanwhile, the contents of five phenolic acids in the kiwifruit wound tissues were increased by methyl jasmonate (MeJA), but reduced by diethyldithiocarbamic acid (DIECA, an inhibitor of JA biosynthesis). Together results indicated that AchMYC2 activated AchPAL, AchC4H and Ach4CL transcription to promote JA-mediated suberin polyphenolic accumulation in the wound healing of kiwifruit.

ABA-responsive transcription factor ABF1-1 promotes JA biosynthesis to accelerate suberin polyphenolic formation in wounded kiwifruit (Actinidia chinensis)

Mechanical damage is a central limiting factor in the maintenance of the postharvest fruit quality during harvest, transportation, and processing. In this study, wounded kiwifruit (Actinidia chinensis cv. Xuxiang) were respectively treated with abscisic acid (ABA), fluridone (FLD, an inhibitor of ABA biosynthesis), methyl jasmonate (MeJA), diethyldithiocarbamic acid (DIECA, an inhibitor of JA biosynthesis), and ABA+DIECA to investigate the potential interaction between ABA and JA in the process of wound healing. The results showed that blocking JA biosynthesis significantly reduced the positive effect of ABA on the accumulation of suberin polyphenolic (SPP). Besides, transiently overexpressed the AchLOX3 and AchOPR3 in tobacco (Nicotiana benthamiana) leaves confirmed that these two genes respectively encoded lipoxygenase and 12-oxo-phytodienoic acid reductase involved in JA biosynthesis. Notably, the positive regulation of transcription factor (TF) AchABF1-1 on AchLOX3 and AchOPR3 was identified. ABA-induced AchABF-1 located in the nucleus and activated the transcriptional expression of AchLOX3 and AchOPR3 through binding to their promoters. These results were further confirmed in the tobacco leaves overexpressing AchABF1-1 in which AchABF1-1 promoted NbLOX and NbOPR expression with the increases of JA content. In addition, exogenous ABA increased endogenous JA content, and enhanced LOX and OPR activities as well as their related gene expression, while FLD reduced these indices. These results suggested that the promotion effect of JA on the SPP accumulation was enhanced through the promotion of JA biosynthesis by ABA-responsive transcription factor AchABF1-1 during the wound healing process of kiwifruit.

SYNTHESIS OF SOME ETHERS OF DIETHYLDITHIOCARBAMIC ACID AND INVESTIGATION OF THEIR INFLUENCE ON ANTI-WEAR AND EXTREME PRESSURE PROPERTIES OF LUBRICATING OILS

By the reaction of sodium diethyldithiocarbamate trihydrate with chlorosubstituted addends – allyl-, tetrahydrofurfuryl monochloroacetate, allyl-3-chloropropanoate and 4-chloromethyl-1,3-dioxolane, the appropriate ethers of diethyldithiocarbamic acid were synthesized. The influence of their composition and structure on the quality of lubricants was investigated.

Methyl jasmonate promotes wound healing by activation of phenylpropanoid metabolism in harvested kiwifruit

A rapid wound healing in vegetables and fruit is instrumental in maintaining fruit quality and extension of shelf life. In this study, wounded kiwifruit were separately treated with methyl jasmonate (MeJA) and diethyldithiocarbamic acid (DIECA, an inhibitor of jasmonate biosynthesis) to evaluate the effect of MeJA on wound healing of kiwifruit. The results showed that MeJA treatment leads to increases of endogenous JA biosynthesis, lipoxygenase (LOX) and 12-oxo-phytodienoic acid reductase (OPR) activities, and JA synthesis genes expression, while DIECA represses these processes. Meanwhile, MeJA promoted the autofluorescence of suberin polyphenolic (SPP) and the accumulation of SPP monomers. MeJA-treated group demonstrated significantly enhanced total phenols, flavonoids, and lignin contents. Besides, MeJA promoted the activities of phenylalanine ammonia-lyase (PAL), cinnamic acid-4-hydroxylase (C4H), 4-COumaric-COA ligase (4CL), peroxidase (POD), polyphenol oxidase (PPO), and the respective gene expression levels. Results suggest that wound healing in kiwifruit could be promoted by MeJA via activation of phenylpropanoid metabolism.

Investigations on the depressant effect of sodium alginate on galena flotation in different sulfide ore collector systems

The depressant effect of sodium alginate on galena flotation in different collector systems was investigated, mainly through micro-flotation tests, zeta potential measurements and molecular dynamics simulations. The micro-flotation results showed that the depressant effect of sodium alginate depended largely on collector type. Galena flotation was effectively and totally depressed by sodium alginate when ammonium dibutyl dithiophosphate acted as collector. When diethyldithiocarbamic acid cyanoethyl ester acted as collector, sodium alginate could only partly inhibit the galena flotation. However, when butyl xanthate acted as collector, sodium alginate could not exhibit any depressant effect on galena flotation. The zeta potential measurement results indicated that these reagents could adsorb on galena surface at different degree of strength and could further result in subsequent different flotation behaviors. The molecular dynamics simulation results demonstrated that the adsorption ability between galena surface and reagents could rank as butyl xanthate > sodium alginate > diethyldithiocarbamic acid cyanoethyl ester > ammonium dibutyl dithiophosphate, which further determined the depressant effect differences. The results could be potentially used for selecting suitable collector type in some sulfide ore flotation plants when sodium alginate acted as galena depressant.

Superoxide anions modulate the effects of alarin in the paraventricular nucleus on sympathetic activity and blood pressure in spontaneously hypertensive rats

Neuropeptides are involved in the regulation of the sympathetic activity and blood pressure in the paraventricular nucleus of the hypothalamus (PVN). The present study was designed to determine how alarin modulates the renal sympathetic nerve activity (RSNA), arterial blood pressure and mean arterial pressure (MAP) in the PVN, and whether superoxide anions regulate the effects of alarin in the PVN of spontaneously hypertensive rats (SHRs). Acute experiment was carried out with male Wistar-Kyoto rats (WKY) and SHRs under anesthesia. RSNA, systolic blood pressure (SBP), diastolic blood pressure (DBP), and MAP were measured. Alarin microinjection into the PVN increased RSNA (7.8 ± 1.8 vs. 14.8 ± 2.3%), SBP (5.9 ± 1.4 vs. 12.1 ± 1.6 mmHg), DBP (5.1 ± 0.8 vs. 10.0 ± 1.1 mmHg), and MAP (5.4 ± 1.2 vs. 10.7 ± 1.3 mmHg) in WKY rats and SHRs,. Alarin antagonist ala6–25 Cys decreased RSNA, SBP, DBP, and MAP in SHRs, and inhibited the effects of alarin. The alarin level was increased in the PVN of SHR compared to WKY rats. (29.7 ± 4.9 vs. 14.6 ± 2.4 pg/mg protein). PVN microinjection of superoxide anion scavengers tempol and tiron, or NAD(P)H oxidase inhibitor apocynin, decreased RSNA, SBP, DBP, and MAP in SHRs, and inhibited the effects of alarin, but the superoxide dismutase inhibitor diethyldithiocarbamic acid potentiated the effects of alarin. Superoxide anions and NAD(P)H oxidase activity levels in the PVN were increased by alarin, but decreased by alarin antagonist ala6–25 Cys. The alarin-induced increases in superoxide anions and NAD(P)H oxidase activity levels were abolished by pre-treatment with ala6–25 Cys. The results suggest that alarin in the PVN increases sympathetic outflow and blood pressure. The enhanced activity of endogenous alarin in the PVN contributes to sympathetic activation in hypertension, and the superoxide anion is involved in these alarin–mediated processes in the PVN.

Autophagy-endoplasmic reticulum stress inhibition mechanism of superoxide dismutase in the formation of calcium oxalate kidney stones

BackgroundNephrolithiasis is a common disease in urology, and its pathogenesis is associated with various factors. Recent studies have shown that reactive oxygen species (ROS) can promote autophagy in the formation of kidney stones and exacerbate kidney injury. Endoplasmic reticulum stress (ERS), a key factor in regulating intracellular environmental homeostasis, is also directly related to ROS production. Therefore, this study aimed to investigate the regulatory effect of superoxide dismutase (SOD) on autophagy-ERS response during the formation of calcium oxalate (CaOx) kidney stones in rats. MethodsThirty-two rats were randomly divided into four groups (n = 8): normal control group, stone model group, stone model with atorvastatin group, and stone model with diethyldithiocarbamic acid (DETC) group. Rat models of CaOx kidney stones were established by intragastric administration of 0.75 % ethylene glycol for 4 weeks. Kidney/body weight was used to assess renal enlargement. Renal function was assessed by measuring serum SOD, creatinine (CRE), and blood urea nitrogen (BUN) levels. The expression of autophagy-related proteins LC3B and BECN1 was detected through immunohistochemical staining. Meanwhile, the expression of autophagy-ERS response-related proteins LC3B, BECN1, p62, GRP78, and CHOP was detected using Western blot and RT-PCR. Renal tubular injury markers neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (Kim-1) were determined through enzyme-linked immunosorbent assay. The apoptosis of renal tubular cells and the expression of their signature proteins cleaved Caspase-3, Bax and Bcl-2 were detected using Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and Western blot assays, respectively. Crystal deposition and histological tissue injury were assessed through Von Kossa staining. ResultsCompared with the control group, the stone model group showed higher kidney/body weight ratio; evidently higher expression of autophagy-ERS response- and apoptosis-related proteins LC3B, BECN1, GRP78, CHOP, Bax and cleaved Caspase-3; and lower levels of p62, bcl-2 protein, and SOD. The stone model group also showed higher levels of apoptosis, serum CRE, BUN, NGAL, and Kim-1, as well as considerably greater crystal deposition and renal injury, than the control group. Atorvastatin reduced the levels of autophagy-ERS response, kidney injury, and crystal deposition, but they were increased by DETC. ConclusionEnhanced SOD activity can protect the kidneys by reducing autophagy-ERS response and CaOx kidney stone formation. Atorvastatin may be a new option for the prevention and treatment of nephrolithiasis.

Potential of jasmonic acid (JA) in accelerating postharvest yellowing of broccoli by promoting its chlorophyll degradation

Chlorophyll degradation is the main reason for postharvest yellowing of broccoli. To uncover the role of jasmonic acid (JA) on the degradation of chlorophyll, broccoli flowers were treated with exogenous methyl jasmonate (MeJA) and diethyldithiocarbamic acid (DIECA). We found a surge of endogenous JA content with the yellowing process, and a significant correlation between JA and chlorophyll content. MeJA treatments led to increased endogenous JA, increased allene oxide cyclase (AOC) activity, and enhanced expression of JA synthesis genes. MeJA caused a stronger reduction in the maximum quantum yield (Fv/Fm), fluorescence decline ratio (Rfd), and total chlorophyll content, advanced the peak of pheide a oxygenase (PAO) activity, and up-regulated the expression of chlorophyll degradation genes. The DIECA treatment resulted in lower endogenous levels of JA, and AOC and 12-oxo-phytodienoic acid reductase (OPR) activity. This study revealed that the potential role of JA on broccoli yellowing is to promote the chlorophyll degradation.

Continuous synthesis of tetraethyl thiuram disulfide with CO2 as acid agent in a gas-liquid microdispersion system

Herein, a continuous synthetic method of tetraethyl thiuram disulfide (TETD) with CO2 as a weak acid reagent in a gas-liquid microdispersion reaction system has been described. A microdispersion reaction system comprising two microreactors for CO2 absorption and diethyldithiocarbamate acid subsequent oxidation reaction was developed. In the first step, the main products of absorption and oxidation reactions were identified. Next, the yield of TETD and selectivity of sodium diethyldithiocarbamate under different flow rates of raw materials, amount of CO2, aging effect, and pressure in the microreaction system were determined. The yield reached 89.03% based on 60% H2O2 dosage and the selectivity was 92.86% in less than 3 min of residence time, which was more than 30 min in the batch process. The space time yield in the microreaction system was ~20 times of that achieved in the batch process. The study provides a new successful reference for replacing batch synthesis by a continuous process using a microreaction system.

Superoxide anions mediate the effects of angiotensin (1-7) analog, alamandine, on blood pressure and sympathetic activity in the paraventricular nucleus

Microinjection of alamandine into the hypothalamic paraventricular nucleus (PVN) increased blood pressure and enhanced sympathetic activity. The aim of this study was to determine if superoxide anions modulate alamandine’s effects in the PVN. Mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) were recorded in anaesthetized normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). Microinjection of alamandine into the PVN increased MAP and RSNA in both WKY rats and SHRs, although to a greater extent in SHRs. These effects were blocked by pretreatment with an alamandine receptor (MrgD) antagonist D-Pro7-Ang-(1–7). Pretreatment with superoxide anion scavengers, tempol and tiron, and NADPH oxidase inhibitor apocynin (APO), also blocked the effects of alamandine on MAP and RSNA. In addition, pretreatment in the PVN with a superoxide dismutase (SOD) inhibitor diethyldithiocarbamic acid (DETC) potentiated the increases of MAP and RSNA induced by alamandine administration, with a greater response observed in SHRs. Superoxide anions and NADPH oxidase levels in the PVN were higher in SHRs than that in WKY rats. Alamandine treatment increased the levels of superoxide anions and NADPH oxidase in WKY and SHRs, however, with greater effect in SHRs. These alamandine-induced increases were inhibited by D-Pro7-Ang-(1–7) pretreatment in the PVN of both rats. These results demonstrate that superoxide anions in the PVN modulate alamandine-induced increases in blood pressure and sympathetic activity in both normotensive and hypertensive rats. Alamandine increases NADPH oxidase activity to induce superoxide anion production, which is mediated by the alamandine receptor.

UV185+254 nm photolysis of typical thiol collectors: decomposition efficiency, mineralization and formation of sulfur byproducts.

The decomposition of toxic flotation reagents upon UV185+254 nm irradiation was attractive due to operational simplicity and no dosage of oxidants. In this work, the degradation of typical thiol collectors (potassium ethyl xanthate (PEX), sodium diethyl dithiocarbamate (SDD), O-isopropyl-N-ethyl thionocarbamate (IET) and dianilino dithiophoshoric acid (DDA)) was investigated by UV185+254 nm photolysis. The degradation efficiencies and mineralization extents of collectors were assessed. The formation of CS2 and H2S byproducts was studied, and the mechanisms of collector degradation were proposed under UV185+254 nm irradiation. The PEX, SDD and IET were decomposed with nearly 100% removal upon 75 min of UV185+254 nm irradiation. The decomposition rate constants decreased in the order SDD > PEX > IET ≫ DDA, and the DDA was the refractory collector. After 120 min of UV185+254 nm irradiation, 15−45% of carbon and 25−75% of sulfur of collectors were completely mineralized, and the mineralization extent decreased in the order PEX > SDD > IET > DDA. The percentage of gaseous sulfur (CS2 and H2S) ranged from 0.48 to 4.85% for four collectors, showing the fraction of emitted sulfur byproducts was small. The aqueous CS2 concentration increased in the first 10−20 min, and was decreased to a low level of 0.05–0.1 mg l−1 at 120 min. Two mechanisms, i.e. direct UV254 nm photolysis and indirect oxidation with free radicals, were responsible for collector decomposition in the UV185+254 nm photolysis.

Superoxide anions modulate the performance of apelin in the paraventricular nucleus on sympathetic activity and blood pressure in spontaneously hypertensive rats

The present study was designed to determine how apelin in paraventricular nucleus (PVN) modulates the renal sympathetic nerve activity (RSNA), arterial blood pressure (ABP), mean arterial pressure (MAP), and heart rate (HR), and whether superoxide anions regulate the performance of PVN apelin in spontaneously hypertensive rats (SHRs). Acute experiment was carried out with 13-week-old male Wistar-Kyoto rats (WKY) and SHRs under anaesthesia. RSNA, ABP, MAP and HR after PVN microinjection were measured. Apelin microinjection into PVN increased RSNA, ABP, MAP and HR in WKY rats and SHRs, more obviously in SHRs. APJ antagonist F13A decreased the RSNA, ABP, MAP and HR in SHRs, and inhibited the effects of apelin. Apelin and APJ mRNA levels were higher in the PVN in SHRs. PVN microinjection of superoxide anion scavengers tempol and tiron, or NAD(P)H oxidase inhibitor apocynin, decreased the RSNA, ABP, MAP and HR in SHRs, and inhibited the effects of apelin, but the superoxide dismutase (SOD) inhibitor diethyldithiocarbamic acid (DETC) potentiated the effects of apelin. NAD(P)H oxidase activity and superoxide anion levels in PVN were increased by apelin, but decreased by APJ antagonist F13A. The apelin-induced increases in NAD(P)H oxidase activity and superoxide anion level were abolished by pre-treatment with F13A. These results indicate that apelin in PVN increases the sympathetic outflow and blood pressure via activating APJ receptor. The enhanced activity of endogenous apelin and APJ receptor in PVN contributes to sympathetic activation in hypertension, and the superoxide anion is involved in these apelin–mediated processes in PVN.

Degradation of Thiol Collectors Using Ozone at a Low Dosage: Kinetics, Mineralization, Ozone Utilization, and Changes of Biodegradability and Water Quality Parameters

Ozonation at a high O3 dosage can achieve high efficiencies in removing flotation reagents but it has a low ozone-utilization rate. The ozonation of potentially toxic thiol collectors (potassium ethyl xanthate (EX), sodium diethyl dithiocarbamate (SN-9), O-isopropyl-N-ethyl thionocarbamate (Z-200) and dianilino dithiophoshoric acid (DDA)) was investigated in an ozone-bubbled reactor at a low O3 dosage of 1.125 mg/(min·L). The degradation kinetics, mineralization, ozone utilization, changes of biodegradability, and water quality parameters were studied, and the degradation behaviors of four collectors were compared. Thiol collectors could be effectively degraded with a removal ratio of >90% and a mineralization ratio of 10‒27%, at a low O3 dosage. The ozonation of thiol collectors followed the pseudo first-order kinetics, and rate constants had the order of kSN-9 > kEX > kZ-200 > kDDA. The Z-200 and DDA were the refractory flotation reagents treated in the ozonation process. After ozonation, the biodegradability of EX, SN-9, and DDA solutions was remarkably raised, but the biodegradability of Z-200 only increased from 0.088 to 0.15, indicating that the Z-200 and its intermediates were biologically persistent organics. After ozonation, the solution pH decreased from 10.0 to 8.0‒9.0, and both the conductivity and oxidation-reduction potential increased. The ozone utilization ratio in decomposing thiol collectors was above 98.41%, revealing almost complete usage of input O3. The results revealed that thiol collectors could be effectively degraded by O3, even at a low dosage, but their degradation behaviors were quite different, due to intrinsic molecular properties.