Increasing H2O2 Concentration Research Articles

Lignocellulosic Properties of Coffee Pulp Waste After Alkaline Hydrogen Peroxide Treatment

The effect of alkaline hydrogen peroxide (AHP) treatment on reducing lignin content in coffee pulp waste (CPW) was investigated to increase the digestibility and accessibility of cellulose during production of valuable products by enzymatic and biological process. Hydrogen peroxide (H2O2) at various concentrations (2.5, 5, and 7.5% (w/w of substrate)) was mixed into 10% (w/v) of CPW-NaOH solution at 35 °C for 24 h with pH 11.5. The concentration of lignocellulosic content was investigated. The characteristic of crystallinity index, functional groups, and surface morphology of CPW at before and after the treatment have been observed using XRD, FTIR, and SEM analysis, respectively. The results showed that the highest lignin removal was achieved at the addition of 7.5% H2O2 which decreased from 16.85% to 8.5%. The concentration of cellulose and hemicellulose in CPW increased from 53% to 64% and 11% to 24%, respectively. The crystallinity index of AHP-treated CPW has increased from 30.83% to 42.08%. A surface morphological destruction on the CPW was getting worse as along with the increase of H2O2 concentration. This would be useful to increase the porosity of biomass to give cellulose accessibility by enzyme for further processes.

Protective effect of hydrogen-rich water on oxidative stress cell model and the impact of the phosphatidylinositol 3 kinase/protein kinase B pathway

To explore the protective effect of hydrogen-rich water on the oxidative stress injury of astrocytes in mice and its effect on phosphatidylinositol 3 kinase/protein kinase B (PI3K/Akt) signal pathway. In vitro, mice astrocytes were cultured and the logarithmic growth period cells were taken for experiment. (1) Experiment one: some cells were acted by 1.25, 2.50, 5.00, 10.00 μmol/L hydrogen peroxide (H2O2) for 20 minutes to determine the appropriate concentration required for astrocyte damage induced by H2O2; cultivating 3, 6, 9, and 12 hours with hydrogen-rich water of 25, 50, 100, and 200 μmol/L, respectively, to determine the concentration and time of hydrogen-rich water pretreatment; the 50 μmol/L hydrogen-rich water was cultured together with PI3K/Akt signal pathway inhibitors wortmannin (WM) 200 nmol/L or 400 nmol/L to determine the best inhibition concentration of wortmannin. Astrocyte activity was detected by methyl thiazolyl tetrazolium (MTT) colorimetry. (2) Experiment two: some cells were divided into blank control group, H2O2 injury group, hydrogen-rich water pretreatment group (HW+H2O2 group), and co-culture of hydrogen-rich water and wortmannin pretreatment group (HW+WM+H2O2 group). The mRNA expressions of PI3K and Akt were detected by reverse transcription-polymerase chain reaction (RT-PCR); the protein expressions of PI3K, Akt and phosphorylated Akt (p-Akt) were detected by Western Blot. (1) Experiment one: the survival rate of the blank control group was 100%. Cell activity gradually decreased with the increase of H2O2 concentration, and the survival rate of the H2O2 action 20 minutes cells of 2.50 μmol/L was reduced to about 50%, so a cell injury model was established at this concentration. With the increase of hydrogen-rich water pretreatment concentration, and the duration of action, the cell survival rate increased first and then decreased. The cell survival rate was highest when 50 μmol/L hydrogen-rich water was pretreated with 9 hours, so a hydrogen-rich water pre-protection model was established. After 200 nmol/L or 400 nmol/L wortmannin was cultured together with hydrogen-rich water, cell activity was inhibited, and the cell survival rate of 200 nmol/L wortmannin group was no significantly different compared with that of H2O2 injury group, so the astrocyte suppression model was established. (2) Experiment two: compared with the blank control group, the mRNA expressions of PI3K and Akt and the protein expressions of PI3K, Akt and p-Akt were significantly decreased in the H2O2 injury group. Compared with the H2O2 injury group, the PI3K, Akt mRNA expressions and PI3K, Akt, p-Akt protein expressions were significantly increased in the HW+H2O2 group [PI3K mRNA (2-ΔΔCT): 0.843±0.019 vs. 0.631±0.038, Akt mRNA (2-ΔΔCT): 0.591±0.025 vs. 0.558±0.037, PI3K/β-actin: 1.277±0.008 vs. 0.757±0.004, Akt/β-actin: 1.308±0.015 vs. 0.682±0.006, p-Akt/β-actin: 1.210±0.005 vs. 0.614±0.005, all P < 0.05]. The mRNA expressions of PI3K, Akt in the HW+WM+H2O2 group was 0.784±0.159 and 0.556±0.037, respectively, and the protein expressions of PI3K, Akt, p-Akt was 0.715±0.006, 0.686±0.005, and 0.606±0.004, respectively, both were significantly lower than those in HW+H2O2 group (all P < 0.05), and there was no significant difference with H2O2 injury group (all P > 0.05). Hydrogen-rich water activates the PI3K/Akt pathway, thereby mediates mice astrocytes to exert the biological function of antioxidant.

Further in vivo evidence implying DNA apurinic/apyrimidinic endonuclease activity in Trypanosoma cruzi oxidative stress survival.

Trypanosoma cruzi is under the attack of reactive species produced by its mammalian and insect hosts. To survive, it must repair its damaged DNA. We have shown that a base excision DNA repair (BER)-specific parasite TcAP1 endonuclease is involved in the resistance to H2 O2 . However, a putative TcAP1 negative dominant form impairing TcAP1 activity in vitro did not show any in vivo effect. Here, we show that a negative dominant form of the human APE1 apurinic/apyrimidinic (AP) endonuclease (hAPE1DN) induces a decrease in epimastigote and metacyclic trypomastigote viability when parasites were exposed to H2 O2 . Those results confirm that TcAP1 AP endonuclease activity plays an important role in epimastigote and in infective metacyclic trypomastigote oxidative DNA damage resistance leading to parasite persistence in the insect and mammalian hosts. All along its biological cycle and in its different cellular forms, T. cruzi, the etiological parasite agent of Chagas' disease, is under the attack of reactive species produced by its mammalian and insect hosts. To survive, T. cruzi must repair their oxidative damaged DNA. We have previously shown that a specific parasite TcAP1 AP endonuclease of the BER is involved in the T. cruzi resistance to oxidative DNA damage. We have also demonstrated that epimastigotes and cell-derived trypomastigotes parasite forms expressing a putative TcAP1 negative dominant form (that impairs the TcAP1 activity in vitro), did not show any in vivo effect in parasite viability when exposed to oxidative stress. In this work, we show the expression of a negative dominant form of the human APE1 AP endonuclease fused to a green fluorescent protein (GFP; hAPE1DN-GFP) in T. cruzi epimastigotes. The fusion protein is found both in the nucleus and cytoplasm of noninfective epimastigotes but only in the nucleus in metacyclic and cell-derived trypomastigote infective forms. Contrarily to the TcAP1 negative dominant form, the ectopic expression of hAPE1DN-GFP induces a decrease in epimastigote and metacyclic trypomastigote viability when parasites were exposed to increasing H2 O2 concentrations. No such effect was evident in expressing hAPE1DN-GFP cell-derived trypomastigotes. Although the viability of both wild-type infective trypomastigote forms diminishes when parasites are submitted to acute oxidative stress, the metacyclic forms are more resistant to H2 O2 exposure than cell-derived trypomastigotes.Those results confirm that the BER pathway and particularly the AP endonuclease activity play an important role in epimastigote and metacyclic trypomastigote oxidative DNA damage resistance leading to parasite survival and persistence inside the mammalian and insect host cells.

Rhizobium tropici CIAT 899 copA gene plays a fundamental role in copper tolerance in both free life and symbiosis with Phaseolus vulgaris.

Rhizobium tropici CIAT 899 is a facultative symbiotic diazotroph able to deal with stressful concentrations of metals. Nevertheless the molecular mechanisms involved in metal tolerance have not been elucidated. Copper (Cu2+) is a metal component essential for the heme-copper respiratory oxidases and enzymes that catalyse redox reactions, however, it is highly toxic when intracellular trace concentrations are surpassed. In this study, we report that R. tropici CIAT 899 is more tolerant to Cu2+ than other Rhizobium and Sinorhizobium species. Through Tn5 random mutagenesis we identify a R. tropici mutant strain with a severe reduction in Cu2+ tolerance. The Tn5 insertion disrupted the gene RTCIAT899_CH17575, encoding a putative heavy metal efflux P1B-1-type ATPase designated as copA. Phaseolus vulgaris plants inoculated with the copA::Tn5 mutant in the presence of toxic Cu2+ concentrations showed a drastic reduction in plant and nodule dry weight, as well as nitrogenase activity. Nodules induced by the copA::Tn5 mutant present an increase in H2O2 concentration, lipoperoxidation and accumulate 40-fold more Cu2+ than nodules formed by the wild-type strain. The copA::Tn5 mutant complemented with the copA gene recovered the wild-type symbiotic phenotypes. Therefore, the copA gene is essential for R. tropici CIAT 899 to survive in copper-rich environments in both free life and symbiosis with P. vulgaris plants.

Kinetics and model development of iohexol degradation during UV/H2O2 and UV/[formula omitted] oxidation

The degradation rates and kinetics of one commonly used iodinated contrast medium, iohexol, were investigated and compared during ultraviolet (UV) photolysis, UV/H2O2 and UV/S2O82− advanced oxidation processes (AOPs). Results indicate that the iohexol degradation rate increased in the order of UV/H2O2 < UV irradiation < UV/S2O82− and followed pseudo-first-order kinetics. Increasing persulfate concentration significantly increased iohexol degradation rate, whereas increasing H2O2 concentration caused reverse effect. Radical scavenging test results show that UV photolysis, OH and ▪ radicals all contributed to iohexol degradation during UV/S2O82−, but OH was the main contributor during UV/H2O2 and was consumed by excess H2O2. The kinetic models of iohexol degradation by both AOPs were developed, and the reaction rate constants with OH and ▪ were calculated as 5.73 (±0.02) × 108 and 3.91 (±0.01) × 1010 M−1 s−1, respectively. Iohexol degradation rate remained stable at pH 5–9 during UV irradiation and UV/H2O2, but gradually decreased at pH 5–7 and remained stable at pH 7–9 during UV/S2O82−. The presence of anions displayed inhibitory effects on iohexol degradation during UV/S2O82− in the order of Cl− >HCO3− ≫ SO42−. UV/S2O82− AOP exhibited high degradation efficiency and stability on the basis of UV irradiation, which can be applied as a promising degradation method for iohexol. UV/S2O82− AOP can effectively mineralize iohexol to CO2 but promoted the generation of toxic iodoform (CHI3), and the subsequent chlorination had the potential to reduce the content of disinfection by-products; therefore, further evaluation of possible environmental hazards is warranted.

Use of mycorrhizal fungi in improving tolerance of the date palm (Phoenix dactylifera L.) seedlings to salt stress

The current study was carried out to assess the response of date palm (Phoenix dactylifera L.) to salinity and to examine the possible role of arbuscular mycorrhizal fungi (AMF) in enhancing the salt tolerance. Plants were grown under non-saline or saline conditions (0 and 240 mM NaCl) with and without AMF inoculation while biochemical, mineral as well as growth parameters were measured in this study. Plant growth parameters including plant height, leaf area and shoot and root dry weight were negatively affected by salinity. However, mycorrhizal plants showed higher growth parameters under saline condition compared to non inoculated salt-affected plants, although root colonization by AMF structures was reduced by salinity. Mycorrhiza mitigated the decrease of K, P and Ca content induced by salinity. Ca/Na and K/Na ratios were also improved in colonized plants. Otherwise, AMF symbiosis improved physiological parameters through elevating stomatal conductance, photosynthetic efficiency and leaf water potential under salinity stress. In the same conditions, mycorrhizal inoculation significantly enhanced concentrations of photosynthetic pigments and protein content. Furthermore, salt stress caused high lipid peroxidation and increased H2O2 content; however, the application of AMF reduced these two parameters in salt-affected plants while activities of antioxidant enzymes (superoxide dismutase, catalase, peroxidase and ascorbate peroxidase) were increased by salt stress and were further enhanced in plants treated with AMF. Overall, it is evident that soil salinity induced detrimental effects on date palm plants, which were lower in mycorrhizal plants than in the non-mycorrhizal ones. In conclusion, colonization with AMF may protect date palm seedlings against the negative salinity influence by mitigating the salt induced oxidative stress.

The Diffusion of Hydrogen Peroxide Into the Liquid Product During Filling Operations Inside Vaporous Hydrogen Peroxide–Sterilized Isolators Can Be Predicted by a Mechanistic Model

Isolators are commonly used in filling operations of pharmaceutical products. To ensure an aseptic inner environment, isolators are regularly sterilized with vaporized hydrogen peroxide. However, despite extensive purging with air, some residual H2O2 remains within the isolator atmosphere and may thus end up in the liquid pharmaceutical drug product, which subsequently may cause oxidation and impact the product’s safety and efficacy. We aimed to evaluate the extent of this phenomenon and to model it. For that purpose, we studied the diffusion of H2O2 into water contained in small recipients exposed to the atmosphere of a H2O2-sterilized small-scale test isolator. Based on the results, a mechanistic model was proposed to estimate the quantity of H2O2 in the product, taking into account the time, filling volume, H2O2 concentration, and a configuration factor. Afterward, this model was challenged by filling water at a manufacturing scale, and we observed that the diffusion model could predict the trend of increasing H2O2 concentration. However, a consistent difference in H2O2 concentration between the model and the experimental results was observed, suggesting the contribution of another parameter. Our results can be used to predict more accurately H2O2 concentration in a pharmaceutical product at the manufacturing level.

The effects of different pharmacological agent treatments on ROS accumulation and functional protein activities in wheat endosperm PCD

Wheat (Triticum aestivum L.) is one of the top three food crops in the world. Studies have revealed that wheat endosperm development undergoes programmed cell death (PCD) process development that may be influenced by PCD. Waterlogging and exogenous hydrogen peroxide (H2O2) treatment exacerbates wheat endosperm PCD, whereas PCD acceleration is significantly inhibited by reactive oxygen species (ROS) scavengers. To explore the physiological mechanism of waterlogging resistance in wheat, the effects of exogenous H2O2, ascorbic acid (AsA), and cyclosporin A (CsA) treatment on ROS content, antioxidant enzyme activity, release of cytochrome c, and caspase-like protease activity in the endosperm of Huamai 8 (waterlogging-tolerant wheat cultivar) and Huamai 9 (waterlogging-sensitive wheat cultivar) were studied. The results showed that exogenous H2O2 treatment resulted in an increase in ROS content, antioxidant enzyme activity, mitochondrial membrane permeability, release of cytochrome c, and caspase-like protease activity in the endosperms of both wheat cultivars, which eventually exacerbated PCD. Compared to Huamai 8, the increase in ROS content in Huamai 9 was more significant, whereas changes in antioxidant enzyme activity, cytochrome c release, mitochondrial membrane permeability, and caspase-like protease activity were smaller. Exogenous AsA treatment leads to the content of H2O2 and catalase activity decrease, which could inhibit endosperm cell death to some extent. CsA treatment effectively inhibited the increase in H2O2 content, antioxidant enzyme activity, release of cytochrome c, and caspase-like protease activity caused by exogenous H2O2 treatment, which in turn inhibited cell death. In summary, exogenous H2O2 treatment aggravates endosperm PCD, and Huamai 9 exhibited higher ROS accumulation and a weaker antioxidant enzyme system under external stress, which may be the mechanisms underlying its sensitivity to waterlogging. CsA effectively inhibited the increase in ROS, antioxidant enzyme activity, cytochrome c release, and cell death. It is possible that in wheat endosperm, mitochondria in a similar way to animal mitochondria release cytochrome c regulating PCD.

Short-term soil-waterlogging contributes to cotton cross tolerance to chronic elevated temperature by regulating ROS metabolism in the subtending leaf

Chronic elevated temperature and soil-waterlogging events often occur concomitantly in the Yangtze River Valley; however, a clear understanding of the effects of aforementioned co-occurring stresses on antioxidant defense in cotton has not been attained. To address this, two temperature conditions during the whole flowering and boll development periods, and three soil-waterlogging levels (0, 3, 6 d) starting on the day of anthesis were established. In the current study, no siginificant difference was observed on plant performance for 3 d soil-waterlogging, whereas 6 d soil-waterlogging event and elevated temperature in isolation negatively affected plant performance (i.e. leaf area declined by 33.3% and 14.7% in AW6 (soil waterlogging for 6 d under ambient temperature regime) and EC (soil well-watered (SRWC(75 ± 5) %) under elevated temperature for 2–3 °C) relative to AC (soil well-watered (SRWC(75 ± 5) %) under ambient temperature regime)) and induced ROS (reactive oxygen species) production and scavenging mechanisms in the subtending leaf of cotton. SOD (superoxide dismutase), CAT (catalase), and POX (peroxidase) activities were increased, and ASA (ascorbic acid) concentration was enhanced due to higher H2O2 (hydrogen peroxide) and O2− accumulations. Whereas, APX (ascorbate peroxidase), DHAR (dehydroascorbate reductase) and GR (glutathione reductase) activities were inhibited under elevated temperature regime or waterlogging event, especially in the treatment of EW6 (soil waterlogging for 6 d under elevated temperature for 2–3 °C), which resulted in increasing H2O2 concentration and higher O2− generation rate. However, plants acclimated to a short-term waterlogging stress (3 d) performed a cross tolerance to chronic elevated temperature regime (leaf number increased by 11.4%, whereas the abscission rate decreased by 4.6% in EW3 (soil waterlogging for 3 d under elevated temperature for 2–3 °C) compared with EC (soil well-watered (SRWC(75 ± 5) %) under elevated temperature for 2–3 °C)). Moreover, plants undergone a brief soil-waterlogging (3 d) induced higher GR activity and increased ASA concentration, along with enhanced SOD, CAT, POX activities, limiting H2O2 and O2− accumulation and reducing oxidative damage to membrane lipids as evidenced by reduced MDA (malondialdehyde) concentration when cotton was subsequently exposed to chronic elevated temperature regime.

Selenium alleviates oxidative stress and autophagy in lead-treated chicken testes

Lead (Pb) is an environmental pollutant and has toxic effect on birds. Selenium (Se) has alleviative effect on Pb poisoning. This study investigated mitigative effect of Se on autophagy in Pb-treated chicken testes. Seven-day-old male chickens were randomly divided into four groups with 45 birds in each group. The birds of the control group were offered drinking water (DW) and commercial diet (CD) (0.49 mg/kg Se). The birds of the Se group were offered DW and CD containing sodium selenite (SeCD) (1.00 mg/kg Se). The birds of the Pb group were offered DW containing lead acetate (PbDW) (350.00 mg/L Pb) and CD. The birds of the Pb/Se group were offered PbDW and SeCD. On the 30th, 60th, and 90th days, respectively; histology, antioxidant indexes (hydrogen peroxide (H2O2), catalase (CAT), total antioxidant capacity (TAOC), reduced glutathione (GSH), and superoxide dismutase (SOD)), mRNA and protein levels of autophagy-related genes (autophagy-related proteins 5, Beclin 1, Dynein, light chain 3 (LC3)-I, LC3-II, and mammalian target of rapamycin (mTOR)) were performed in chicken testes. The results of this study showed that Pb caused histological changes; increased H2O2 content; decreased CAT, TAOC, and SOD activities and GSH content; and increased mRNA and protein levels of the above autophagy-related genes except that mTOR decreased in chicken testes. Se alleviated the above changes. Se alleviated histological damage, oxidative stress, and autophagy in the Pb-treated chicken testes.

Are Myriophyllum alterniflorum biomarker responses to arsenic stress differentially affected by hydrodynamic conditions?

Arsenic (As) is a significant contaminant in the environment and its detection through macrophytes can provide a powerful tool. Myriophyllum alterniflorum constitutes a good candidate by virtue of its ability to accumulate contaminants, and moreover its biomarkers can respond to the presence of trace metals and metalloids. The objective of this study therefore is to evaluate the watermilfoil response to As exposure under several hydrodynamic conditions since it is well known that hydrodynamics affect plant functioning. For this purpose, fresh watermilfoil plants are subjected to three hydrodynamic conditions, namely laminar, turbulent and calm, in a synthetic medium either enriched or not by 100 μg.L−1 arsenic for 21 days. Growth, pigment content (chlorophyll a, b and carotenoids), respiratory and photosynthetic activities, osmotic potential and hydrogen peroxide concentration are all monitored. Arsenic accumulation is measured separately in the roots and shoots of Myriophyllum alterniflorum. On the one hand, it should be noted that arsenic induces: (i) a significant increase in H2O2 content; (ii) a decrease in osmotic potential, pigment content, photosynthesis and respiration rates, shoot and root growth; and (iii) an inhibition of shoot branching. Moreover, a higher accumulation of this metalloid in roots than in shoots, regardless of the hydrodynamic condition, is witnessed. While on the other hand, hydrodynamic conditions only affect watermilfoil morphology and arsenic accumulation. Also, the younger and older parts have experienced differential toxic effects. Overall, our results suggest the effective use of M. alterniflorum in both water quality biomonitoring and phytoremediation studies.

Effect of dietary Bio-fermented selenium on growth performance, nonspecific immune enzyme, proximate composition and bioaccumulation of zebrafish (Danio rerio)

A four-weeks feeding trial was conducted to evaluate the effects of dietary Bio-fermented selenium (Bio-Se) on zebrafish (Danio rerio). Effects of three Se diets containing basal diet (1.63 mg Se/kg), L-Se diet (3 mg Se/kg), and H-Se diet (10 mg Se/kg) on growth performance, nonspecific immune enzyme activities, proximate composition, and selenium accumulation of zebrafish were tested. The results indicate that body weight gain (BWG), specific growth rate (SGR), and nonspecific immune enzyme [glutathione peroxidase (GPx), superoxide dismutase (SOD), and alkaline phosphatase (ALP)] activities of fish fed with L-Se diet were significantly highest among all the groups. However, increased H2O2 content and decreased SOD activity indicates oxidative stress when fish was fed with H-Se diet. Dietary Se did not affect the proximate composition of zebrafish. The Se concentration in muscle increased in a dose-dependent manner, and the highest Se concentration was recorded in H-Se diet. In summary, the growth performance and nonspecific immunity of zebrafish fed with L-Se diet improved, but exposure to higher concentrations of Bio-Se severely affects the health status of fish.

The regulation of P700 is an important photoprotective mechanism to NaCl-salinity in Jatropha curcas.

Salinity commonly affects photosynthesis and crop production worldwide. Salt stress disrupts the fine balance between photosynthetic electron transport and the Calvin cycle reactions, leading to over-reduction and excess energy within the thylakoids. The excess energy triggers reactive oxygen species (ROS) overproduction that causes photoinhibition in both photosystems (PS) I and II. However, the role of PSI photoinhibition and its physiological mechanisms for photoprotection have not yet been fully elucidated. In the present study, we analyzed the effects of 15 consecutive days of 100 mM NaCl in Jatropha curcas plants, primarily focusing on the photosynthetic electron flow at PSI level. We found that J. curcas plants have important photoprotective mechanisms to cope with the harmful effects of salinity. We show that maintaining P700 in an oxidized state is an important photoprotector mechanism, avoiding ROS burst in J. curcas exposed to salinity. In addition, upon photoinhibition of PSI, the highly reduced electron transport chain triggers a significant increase in H2 O2 content which can lead to the production of hydroxyl radical by Mehler reactions in chloroplast, thereby increasing PSI photoinhibition.

Impacts of warming and water deficit on antioxidant responses in Panicum maximum Jacq.

Agricultural activities are affected by many biotic and abiotic stresses associated with global climate change. Predicting the response of plants to abiotic stress under future climate scenarios requires an understanding of plant biochemical performance in simulated stress conditions. In this study, the antioxidant response of Panicum maximum Jacq. cv. Mombaça exposed to warming (+2°C above ambient temperature) (eT), water deficit (wS) and the combination eT + wS was analysed under field conditions using a temperature free-air-controlled enhancement facility. Warming was applied during the entire growth period. Data were collected at 13, 19 and 37 days after the start of the water deficit treatment (DAT) and at two sampling times (6:00 and 12:00 h). A significant decrease in chlorophyll was observed under the wS treatment, but an increment in total chlorophyll was observed in eT + wS, particularly at 19 DAT. Significant increase in H2 O2 content, malondialdehyde and protein oxidation was observed in the wS treatment at noon of the third sampling. In the combined wS + eT stress treatment, the activity of the enzymatic antioxidant system increased, particularly of superoxide dismutase (SOD; EC 1.15.1.1) and ascorbate peroxidase (APX; EC 1.11.1.11). The chlorophyll fluorescence images showed that the photochemical performance was not significantly affected by the treatments. In conclusion, under simulated future warming and water stress conditions, the photosystem II (PSII) activity of P. maximum acclimated to moderate warming and a water-stressed environment associated with a relatively favourable antioxidant response, particularly in the activity of APX and SOD.

Effect of hydrogen peroxide on photoelectric properties of high-transmittance FTO films prepared by spray pyrolysis

The FTO film prepared by spray pyrolysis has low efficiency and most of the precursors are discharged in the form of waste steam. According to the high oxidation property of H2O2, it is attempted to improve the film formation rate by changing the concentration of H2O2. Fluorine-doped SnO2 (FTO) thin films with high transmittance were prepared by spray pyrolysis using monobutyltin trichloride as the tin source and ammonium fluoride as the fluorine source. Different concentrations of hydrogen peroxide (0–0.08 M) are added to the precursor solution. In this paper, we studied the effect of hydrogen peroxide on the structure, surface morphology and photoelectric properties of FTO thin films. The results show that the growth rate of the FTO films increased from 6.04 nm/s to 8.36 nm/s with the increase of H2O2 concentration from 0 to 0.08 M. The optimum preparation process is H2O2 concentration controlled at 0.04 M, and FTO thin films suitable for solar cells are prepared. It has excellent performance parameters; carrier concentration:2.74 ∗ 1021 cm−3; carrier mobility:55.92 cm2 V−1 s−1; photoelectric quality factor:2.66 × 10−3·Ω−1and the average transmittance of visible light: 79.87%. At the same time, increasing H2O2 concentration leads to narrowing of optical band gap. Adding appropriate hydrogen peroxide concentration can improve the film production rate and obtain excellent quality films.

Electrochemical characterization of ruthenium dissolution and chemical mechanical polishing in hydrogen peroxide based slurries

Abstract Chemical mechanical planarization of ruthenium (Ru) in a slurry formulation containing silica abrasive and hydrogen peroxide oxidizer was investigated. The removal rate and the etch rate increase with increase in oxidizer concentration due to increased oxide formation on Ru surface. The removal rate selectivity and the galvanic corrosion of Ru/Cu couple were also studied. In the presence of oxidizer, formation of RuO2, Ru(OH)3, Ru(OH)4, RuO4─ and RuO42─ takes place in alkaline pH. The removal mechanism of the metals was studied using electrochemical techniques in the presence of a supporting electrolyte i.e., sodium perchlorate (NaClO4) and varying concentration of H2O2 solution. The electrochemical characterization was carried out at natural pH varying the hydrogen peroxide concentration. The Icorr values calculated using the extrapolation of potentiodynamic polarization plots follow the similar trend as the CMP removal rate. The electrochemical impedance spectroscopy (EIS) results of Ru and Cu show decreased impedance values with increase in H2O2 concentration which matches well with the etch rate and CMP experiments. Kramer-Kronig Transformation (KKT) was used to check the stability, linearity and causality of the system.

Effects of oxidative modification on textural properties and gel structure of pork myofibrillar proteins

Isolated myofibrillar protein (MP) was treated by the oxidation system of FeCl3 (0.01 mM) at four different H2O2 concentrations (0, 1, 10, 20 mM). The oxidation degree was determined by measuring the carbonyl and total sulphydryl values. The structure and physicochemical properties of MP gels were investigated by water holding capacity (WHC) evaluation, sodium dodecyl sulfate-polyacryl amide gel electrophoresis (SDS-PAGE), texture profile analysis (TPA), Raman spectroscopy, and NMR transverse relaxation (T2). The results of carbonyls and total sulphydryls indicated that oxidation degree of MP increased with increasing H2O2 concentration. TPA showed that moderate oxidation (10 mM H2O2) could improve the hardness, springiness, gumminess and cohesiveness of MP gels, but not contribute to the maintenance of their WHC, probably due to severe depolymerization of MPs, unfolding of α-helix, exposure of the hydrophobic groups and the migration of protein-associated water (T2b) and intra-myofibrillar water (T21) to the longer relaxation time.

Antioxidant metabolism in stem and calyx end tissues in relation to flesh browning development during storage of 1-methylcyclopropene treated ‘Empire’ apples

Development of firm flesh browning, a physiological disorder, in ‘Empire’ apples during long term controlled atmosphere (CA) storage, can be enhanced by 1-methylcyclopropene (1-MCP), an inhibitor of ethylene perception. The disorder develops earlier in stem-end tissues than in calyx-end tissues. The antioxidant scavenging systems in the tissue zones of fruit stored under CA conditions (2 kPa O2/2 kPa CO2) at 3 °C at 6 and 10 months were investigated. Flesh tissue browning as indicated by lightness and hue angle was greater in 1-MCP treated than in untreated fruit, and in stem-end tissues than in calyx-end tissues. 1-MCP treatment decreased superoxide production as indicated by nitroblue tetrazolium (NBT) reducing activity but increased H2O2 concentrations, while treatment effects on malondialdehyde concentrations were inconsistent. Ascorbic acid (AsA) and glutathione (GSH) concentrations declined during storage, regardless of 1-MCP treatment, but were lower in stem-end tissue than in calyx-end tissue. While ascorbate peroxidase (APX) activity was not affected by 1-MCP treatment, its activity in untreated fruit was lower in stem-end tissues than in calyx-end tissues. The activities of superoxide dismutase (SOD) and copper/zinc-superoxide dismutase (Cu/Zn-SOD) increased during storage. The activities of catalase (CAT) and peroxidase (POX) decreased in 1-MCP treated fruit but effects on activities of other enzymes were inconsistent. Overall, higher browning may be associated with lower AsA and GSH concentrations in stem-end tissues, but the enhanced browning resulting from 1-MCP treatment does not appear to be directly related to antioxidant metabolism.

Salicylic Acid and Hydrogen Peroxide Accumulation in Relation to Hydrolyte Leakage in Barley Plants Challenged with Cochliobolus sativus

Spot blotch (SB) caused by the hemibiotrophic fungal pathogen Cochliobolus sativus is a destructive disease of barley worldwide. To better understand the mechanisms of resistance to this disease, the involvements of salicylic acid (SA), hydrogen peroxide (H2O2) and ion fluxes during the interaction between resistant and susceptible barley seedlings and C. sativus were investigated. Early SA accumulation in leaf tissues was accompanied with an increase in H2O2 concentration in both compatible and incompatible interactions. The resistant cultivar constitutively contained higher levels of H2O2 and SA, as well as during the 72 h as compared with the un-infected control (0 h). However, levels increased rapidly upon infection in both cultivars. Moreover, a markedly greater increase in ion fluxes from the compatible material compared with the incompatible one was observed. Results suggest that SA and H2O2 accumulation are important during both compatible and incompatible barley-C. sativus interactions.

Changes in the photosynthesis properties and photoprotection capacity in rice (Oryza sativa) grown under red, blue, or white light.

Non-photochemical quenching (NPQ) of the excited state of chlorophyll a is a major photoprotective mechanism plants utilize to survive under high light. Here, we report the impact of long-term light quality treatment on photosynthetic properties, especially NPQ in rice. We used three LED-based light regimes, i.e., red (648-672nm), blue (438-460nm), and "warm" white light (529-624nm), with the incident photon flux density of 300µmolphotonsm-2s-1, the difference in the absorbed photon flux densities by leaves grown under different light quality being less than 7%. Our results show that blue light, as compared to white light, induced a significant decrease in Fv/Fm, a decreased rate of reduction of P700+ after P700 was completely oxidized; furthermore, blue light also induced higher NPQ with an increased initial speed of NPQ induction, which corresponds to the qE component of NPQ, and a lower maximum quantum yield of PSII, i.e., Y(II). In contrast, rice grown under long-term red light showed decreased Y(II) and increased NPQ, but with no change in Fv/Fm. Furthermore, we found that rice grown under either blue or red light showed decreased transcript abundance of both catalase and ascorbate peroxidase, together with an increased H2O2 content, as compared to rice grown under white light. All these data suggest that even under a moderate incident light level, rice grown under blue or red light led to compromised antioxidant system, which contributed to decreased quantum yield of photosystem II and increased NPQ.