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1.
Cr(VI) and phenol are toxic contaminants that need to be treated, and different methods have been researched to simultaneously remove these two contaminants from industrial wastewater. In this study, Cr(VI) was used as a novel Fenton-like catalyst in phenol degradation by H2O2. In the pH range of 3.0‒11.0, the degradation efficiency of phenol decreased with elevated pH. At pH = 3.0, 100 mg/L phenol was effectively degraded by 2 mmol/L Cr(VI) and 20 mmol/L H2O2. At pH = 7.0 and the same conditions as those of pH = 3.0, 79% of 100 mg/L phenol was removed within 6 h, which was an improvement in pH limitation compared with the Fe(II)-mediated Fenton reaction. Quenching experiments indicated that ·OH generated from the catalysis of H2O2 by Cr(V) instead of Cr(VI) was the primary oxidant that degraded phenol. When pyrophosphate was added in the Cr(VI)/H2O2 system, complexes with the Cr(V) intermediate rapidly formed and inhibited H2O2 decomposition, implying that the decomposition of H2O2 to ·OH was catalyzed by Cr(V) instead of Cr(VI). The presence of anions such as chloride and sulfate had insignificant effect on the degradation of phenol. TOC and UV analyses suggest that phenol could not be completely oxidized to CO2 and H2O, and the intermediates identified by high performance liquid chromatography further indicates that maleic acid and benzoquinone were intermediates which may be further degraded into short chain acids, primarily maleic, formic, acetic, and oxalic acids, and eventually into CO2 and H2O. Considering that more than 50% Cr(VI) can also be removed during this process, the Cr(VI)/H2O2 system is more appropriate for the simultaneous removal of Cr(VI) and phenol contaminants from industrial wastewater. 相似文献
2.
Composite materials of Fe/Al 2O 3, which consist of small particles of iron supported by thermally stable alumina even at 500–700 °C, have been widely used in the water-gas shift reaction for natural gas reforming. Therefore, Fe/Al 2O 3 is one of the promising candidates for re-transformation of exhausted CO 2 into fuels such as alcohols and hydrocarbons. The development of a CO 2 reforming system using the composite materials of Fe/Al 2O 3 through CO 2 reduction to CO, dissociation of water into hydrogen, and methanol synthesis has been investigated. It was found that dry and steam (i.e. wet) reforming of CO 2 produced almost the same amount of CO. At a temperature above 500 °C, maximal and saturated yields of CO and H 2 from CO 2 and water were obtained. However, this CO 2 reforming system requires higher-pressure conditions from several tens to hundreds standard atmospheric pressure in order to achieve high yield and selectivity for methanol production. In this study we developed the modified CO 2 reforming system by the utilization of Ni and/or Cu instead of Fe in order to obtain other types of useful products such as CO, CH 4, and carbon, more efficiently and selectively under atmospheric pressure. When Ni or Cu was used, conversion of CO 2 was reduced to 76%, while 9% of methane was detected in the case of Ni. On the other hand, though the CO 2 conversion reduced half of the Fe, the selectivity of CO from CO 2 increased to 95% in the case of Cu. 相似文献
3.
Cucumber and rice plants with varying ammonium (NH 4
+) sensitivities were used to examine the effects of different nitrogen (N) sources on gas exchange, chlorophyll (Chl) fluorescence
quenching, and photosynthetic electron allocation. Compared to nitrate (NO 3
−)-grown plants, cucumber plants grown under NH 4
+-nutrition showed decreased plant growth, net photosynthetic rate, stomatal conductance, intercellular carbon dioxide (CO 2) level, transpiration rate, maximum photochemical efficiency of photosystem II, and O 2-independent alternative electron flux, and increased O 2-dependent alternative electron flux. However, the N source had little effect on gas exchange, Chl a fluorescence parameters, and photosynthetic electron allocation in rice plants, except that NH 4
+-grown plants had a higher O 2-independent alternative electron flux than NO 3
−-grown plants. NO 3
− reduction activity was rarely detected in leaves of NH 4
+-grown cucumber plants, but was high in NH 4
+-grown rice plants. These results demonstrate that significant amounts of photosynthetic electron transport were coupled to
NO 3
− assimilation, an effect more significant in NO 3
−-grown plants than in NH 4
+-grown plants. Meanwhile, NH 4
+-tolerant plants exhibited a higher demand for the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) for
NO 3
− reduction, regardless of the N form supplied, while NH 4
+-sensitive plants had a high water-water cycle activity when NH 4
+ was supplied as the sole N source. 相似文献
4.
Molecular O 2 and H 2O are the vital requirements of contemporary life. The evolution of the atmosphere and oceans, therefore, necessarily predates
metazoan evolution on the earth. The prebiotic primary atmosphere had CH 4, NH 3 and H 2 as the chief components and was O 2-deficient. Dissociation of CH 4 and NH 3 paved the way for the secondary atmosphere composed principally of CO 2. 相似文献
5.
Objective:To evaluate the effect of chitosan(CH) and hydrogen peroxide(H2O2) seed coatings and seedling sprinklings on two different maize varieties by measuring their phenology,the H2O2 presence,the catalase(CAT) activity,and the protein quantity.Methods:Seven groups of ten seeds for each maize variety were treated with CH(2%(20 g/L) and 0.2%(2 g/L)) or H2O2(8 mmol/L) by coating,sprinkling,or both.Germination and seedling growth were measured.One month after germination,the presence of H2O2 in seedlings in the coated seed treatments was evaluated.Protein content and CAT activity were determined under all treatments.Results:H2O2 seed coating enhanced the germination rate and increased seedling and stem length in the quality protein maize(QPM) variety.Seedlings had a higher emergence velocity under this treatment in both varieties.CH and H2O2 sprinklings did not have an effect on seedling phenology.Exogenous application of H2O2 promoted an increase of endogenous H2O2.CH and H2O2 seedling sprinkling increased the protein content in both maize varieties,while there was no significant effect on the CAT activity of treated seeds and seedlings.Conclusions:CH and H2O2 enhance some phenological and biochemical features of maize depending on their method of application. 相似文献
6.
ObjectiveTo investigate the protective effects of parecoxib from oxidative stress induced by hydrogen peroxide (H2O2) in rat astrocytes in vitro.MethodsAll experiments included 4 groups: (1) negative control (NC) group, without any treatment; (2) H2O2 treatment group, 100 µmol/L H2O2 treatment for 24 h; (3) and (4) parecoxib pretreatment groups, 80 and 160 µmol/L parecoxib treatment for 24 h, respectively, and then treated with 100 µmol/L H2O2. Several indices were investigated, and the expressions of Bax, Bcl-2, and brain-derived neurotrophic factor (BDNF) were quantified.ResultsCompared to the NC group, exposure to H2O2 resulted in significant morphological changes, which could be reversed by pretreatment of parecoxib. In addition, H2O2 treatment led to loss of viability (P=0.026) and increased intracellular reactive oxygen species (ROS) levels (P<0.001), and induced apoptosis (P<0.01) in the primary astrocytes relative to the NC group. However, in the parecoxib pretreatment groups, all the above changes reversed significantly (P<0.05) as compared to the H2O2 treatment group, and were nearly unchanged when compared to the NC group. Mechanical investigation showed that dysregulated Bax, Bcl-2, and BDNF could be implicated in these changes.ConclusionsOur results indicated that parecoxib provided a protective effect from oxidative stress induced by exposure to H2O2. 相似文献
7.
Oat contains different components that possess antioxidant properties;no study to date has addressed the antioxidant effect of the extract of oat bran on the cellular level.Therefore,the present study focuses on the investigation of the protective effect of oat bran extract by enzymatic hydrolysates on human dermal fibroblast injury induced by hydrogen peroxide(H2O2).Kjeldahl determination,phenol-sulfuric acid method,and high-performance liquid chromatography(HPLC) analysis indicated that the enzymatic products of oat bran contain a protein amount of 71.93%,of which 97.43% are peptides with a molecular range from 438.56 to 1 301.01 Da.Assays for 1,1-diphenyl-2-picrylhydrazyl(DPPH) radical scavenging activity indicate that oat peptide-rich extract has a direct and concentration-dependent antioxidant activity.3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) colorimetric assay and the TdT-mediated digoxigenin-dUTP nick-end labeling(TUNEL) assay for apoptosis showed that administration of H2O2 in human dermal fibroblasts caused cell damage and apoptosis.Pre-incubation of human dermal fibroblasts with the Oatp for 24 h markedly inhibited human dermal fibroblast injury induced by H2O2,but application oat peptides with H2O2 at same time did not.Pre-treatment of human dermal fibroblasts with Oatp significantly reversed the H2O2-induced decrease of superoxide dismutase(SOD) and the inhibition of malondialdehyde(MDA).The results demonstrate that oat peptides possess antioxidant activity and are effective against H2O2-induced human dermal fibroblast injury by the enhanced activity of SOD and decrease in MDA level.Our results suggest that oat bran will have the potential to be further explored as an antioxidant functional food in the prevention of aging-related skin injury. 相似文献
8.
目的:研究硝酸钙胁迫下24-表油菜素内酯(EBR)对黄瓜幼苗抗氧化性能及可溶性蛋白表达的影响。方法:通过单因素随机区组设计,从其抗氧化性能及可溶性蛋白表达的变化来探讨EBR对硝酸钙胁迫下黄瓜幼苗的影响。结果:与对照相比,硝酸钙胁迫导致黄瓜幼苗的丙二醛含量及细胞膜透性显著提高了115.1%和105.6%,膜脂过氧化加剧,黄瓜根系中可溶性蛋白含量降低且至少有35种蛋白发生明显变化,而叶片的可溶性蛋白含量升高且至少有29种蛋白发生明显变化;而硝酸钙胁迫下喷施EBR后黄瓜幼苗的SOD、POD、CAT分别比单纯的硝酸钙胁迫增加了20.2%、20.3%、34.4%,并提高了其可溶性蛋白含量及其表达的变化幅度。结论:24-表油菜素内酯可通过调节硝酸钙胁迫下黄瓜幼苗抗氧化性、可溶性蛋白含量及其表达,进而降低其膜脂过氧化程度,以缓解硝酸钙胁迫对植株的伤害。 相似文献
9.
Homogeneous, crack-free SrNb xTi 1−x
O 3 thin films on (110) silicon substrates were successfully fabricated by sol-gel processing. The optimum route and conditions
were systematically investigated. Sr(OAc) 2 glacial acctic acid solution, after being refluxed and reacted with tartrate, formed Sr(OAc) 2(C 4H 6O 6) 2; Ti(OBu) 4 formed Ti(OAc) 4−x
(AcAc) x after having the ligand partially exchanged with AcAc, while Nb(OC 2H 5) 5 formed (OAc) 2Nb(AcAc) (C 4H 6O 6) by exchanging of ligand in glacial acetic acid with (CH 3CO) 2O. All the metal species after undergoing partial hydrolysis and polymerization with hydroxyl or oxygen, formed SrNb xTi 1−x
O 13 cluster sol. Methyl cellulose (MCL) caused SrNb xTi 1−x
O 3 sol to have polymeric structure and easily form films. SrNb xTi 1−x
O 3 films with perovskite were subsequently formed after being annealed at 650∼750 °C for 60 min in 25% N 2+75% H 2 (volume ratio) atmosphere. Resistivity of the SrNb 0.1Ti 0.9O 3 films at room temperature was 64 μω·cm, a particular T
2 temperature dependence of the resistivity, from 25 K up to room temperature, was observed.
Project (No. 2002CB613305) supported by the National Basic Research Program (973) of China 相似文献
10.
Transgenic rice plants with an antisense gene inserted via Agrobacterium tumefaciens were used to explore the impact of the reduction of Rubisco activase (RCA) on Rubisco and photosynthesis. In this study, transformants containing 15% to 35% wild type Rubisco activase were selected, which could survive in ambient CO2 concentration but grew slowly compared with wild type controls. Gas exchange measurements indicated that the rate of photosynthesis decreased significantly, while stomatal conductance and transpiration rate did not change; and that the intercellular CO2 concentration even increased. Rubisco determination showed that these plants had approximately twice as much Rubisco as the wild types,although they showed 70% lower rate of photosynthesis, which was likely an acclimation response to the reduction inRubsico activase and/or the reduction in carbamylation. 相似文献
11.
INTRODUCTION Ribulose-1,5-bisphosphate carboxylase/oxy-genase (Rubisco) is a key enzyme that initiates bothphotosynthetic and photorespiratory carbon me-tabolism. However, Rubisco has to be activated andcarbamylated to become catalytically competent.Rubisco activase (RCA) can alter the activity ofRubisco by facilitating the dissociation of tightlybound sugar phosphates from Rubisco in a processthat requires ATP hydrolysis. RCA, a chloroplastprotein encoded by a nuclea… 相似文献
12.
The precursor of ultrafine In2O3 powder was prepared by the hydrolysis,peptization and gelation of InCl3.4H2O used as raw material.After calcination,ultrafine In2O3 powder was obtained.The particles were characterized by the methods of thermo-gravimetric and differential thermal analysis(TG-DTA),X-ray diffractometry(XRD) and transmission electron microscopy(TEM).respectively. 相似文献
13.
With InCl 3·4H 2O being used as raw materials, the precursor of nano-sized In 2O 3 powder was prepared by hydrolysis, peptization and gelation of InCl 3·4H 2O. After calcination, nano-sized In 2O 3 powder was obtained. The powder was characterized by thermo-gravimetric and differential thermal analysis (TG-DTA), X-ray
diffractometry (XRD) and transmission electron microscopy (TEM), respectively. Calculation revealed that the mean crystalline
size increased with increasing the calcination temperature, but crystal lattice distortion rate decreased with the increasing
in the average crystalline size. This indicated that the smaller the particle size, the bigger the crystal lattice distortion,
the worse the crystal growing. The activation energies for growth of nano-sized In 2O 3 were calculated to be 4.75 kJ·mol −1 at the calcination temperature up to 500°C; and 66.40 kJ·mol −1 at the calcination temperature over 600°C. TEM photos revealed that the addition of the chemical additive (OP-10) greatly
influenced the morphology and size of In 2O 3 particles. 相似文献
14.
Ultrafine γ-Al 2O 3 particles are synthesized in Triton X-100/ n-hexanol/cyclohexane/water water in oil(w/o) microemulsion by mixing two separately prepared microemulsions containing Al(NO) 3 and (NH 4) 2CO 3 respectively. The ultrafine Al 2O 3 particles are characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) and their size and distribution
are measured. The effects of water, surfactant and reactant concentrations on the particle size and distribution are studied.
The results show that the particle size and distribution can be changed by varying the preparation conditions, and the size
of the microemulsion droplets has a controlling effect on the size of the particles. A possible mechanism of ultrafine particles
(UFPs) prepared by microemulsions is proposed. 相似文献
15.
In this study,Pd-Mg(Al)-LDH/γ-Al_2O_3 and Pd-Mg(Al)Zr-LDH/γ-Al_2O_3 precursors were synthesized by impregnating Na_2PdCl_4 on Mg(Al)-LDH/γ-Al_2O_3 and Mg(Al)Zr-LDH/γ-Al_2O_3,and then the precursors were calcinated and reduced to obtain Pd-Mg(Al)-MMO/γ-Al_2O_3 and Pd-Mg(Al)Zr-MMO/γ-Al_2O_3 catalysts.Compared with Pd/γ-Al_2O_3 catalyst,the hydrogenation efficiency of Pd-Mg(Al)-MMO/γ-Al_2O_3 and Pd-Mg(Al)Zr-MMO/γ-Al_2O_3 increased by 15.7%and 24.0%,respectively.Moreover,the stability of Pd-Mg(Al)Zr-MMO/γ-Al_2O_3 catalyst was also higher than that of Pd/γ-Al_2O_3.After four runs,the hydrogenation efficiency of Pd/γ-Al_2O_3 decreased from 12.1 to 10.0 g/L,while that of Pd-Mg(Al)Zr-MMO/γ-Al_2O_3 decreased from 15.0 to 14.3 g/L.The active aquinones selectivities of all catalysts were almost 99%.The structures of the catalysts were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),N_2 adsorption-desorption,inductively coupled plasma-atomic emission spectrometry (ICP-AES),CO chemisorption analysis,transmission electron microscopy (TEM),temperature-programmed reduction with hydrogen (H_2-TPR),and X-ray photoelectron spectroscopy(XPS).The results indicate that the improved catalytic performance is attributed to the stronger interaction between Pd and Mg(Al)Zr-MMO/γ-Al_2O_3,smaller Pd particle size and higher Pd dispersion.This work develops an effective method to synthesize highly dispersed Pd nanoparticles based on the layered double hydroxides (LDHs) precursor. 相似文献
16.
We first report discovery of the spinel-garnet-orthopyroxene granulite with pure CO 2 fluid inclusions from the Fuyun region of the late Paleozoic Altay orogenic belt in Central Asia, NW China. The rock is characterized
by an assemblage of garnet, orthopyroxene spinel, cordierite, biotite, plagioclase and quartz. Symplectites of orthopyroxene
and spinel, and orthopyroxene and cordierite indicate decompression under UHT conditions. Mineral chemistry shows that the
orthopyroxenes have high X Mg and Al 2O 3 contents (up to 9.23 wt%). Biotites are enriched in TiO 2 and X Mg and are stable under granulite facies conditions. The garnet and quartz from the rock carry monophase fluid inclusions which
show peak melting temperatures of around-56.7°C, indicating a pure CO 2 species being presented during the ultrahigh-T metamorphism in the Altay orogenic belt. The inclusions homogenize into a
liquid phase at temperatures around 15.3–23.8°C translating into CO 2 of the order of 0.86–0.88 g/cm 3. Based on preliminary minerals paragenesis, reaction textures and petrogenetic grid considerations, we infer that the rock
was subjected to UHT conditions. The CO 2-rich fluids were trapped during exhumation along a clockwise P-T path following isothermal decompression under UHT conditions.
Project supported by the National Basic Research Program (973) of China (No. 2001CB409801), the Exemplary Young Teacher Education
and Scientific Research Award Plan of China University, and Postdoctoral Fund of China (No. 2003033033), Postdoctoral Fund
of Zhejiang Province, and Starting Fund of Education Ministry, China 相似文献
17.
The controllable active thermo-atmosphere combustor (CATAC) has become a utilizable and effective facility because it benefits
the optical diagnostics and modeling. This paper presents the modeling research of the auto-ignition and flames of the H 2/N 2 (H 2/CH 4/N 2, or H 2/H 2O 2/N 2) mixture on a CATAC, and shows curves varying with temperatures of auto-ignition delay, the height of the site of auto-ignition
of lifted flames, and flame lift-off height. The results of auto-ignition delay and the lift-off height are compared the experimental
results to validate the model. A turning point can be seen on each curve, identified with criterion temperature. It can be
concluded that when the co-flow temperature is higher than the criterion temperature, the auto-ignition and lifted flame of
the mixture are not stable. Conversely, below the criterion temperature, the mixture will auto-ignite in a stable fashion.
Stabilization mechanisms of auto-ignition and lifted flames are analyzed in terms of the criterion temperature. 相似文献
18.
The metal oxide/nitrogen-doped carbon (NC) compounds zirconium oxide/NC (ZrO2/NC) and cerium oxide/NC (CeO2/NC) were synthesized via the pyrolysis of polyaniline on the metal oxide surface. The characterization of the ZrO2/NC and CeO2/NC catalysts showed more active CO2 reduction reaction activity than that of NC catalyst without metal oxide. Gas chromatography analysis revealed that CO and H2 were the primary products, and no liquid-phase products were detected via proton nuclear magnetic resonance spectroscopy or high-performance liquid chromatography. The maximum Faraday efficiency of ZrO2/NC reached 90% at − 0.73 V (vs. RHE), with the current density of CO at 5.5 mA/cm2; this Faraday efficiency value was higher than that of NC (41%), with the current density of CO at 3.1 mA/cm2. The interaction between the metal oxide and carbon allowed the efficient formation of defect sites, especially imine-type nitrogen, strengthening the adsorption of the key reaction intermediate CO2•− and thus promoting the CO2 reduction reaction. 相似文献
19.
In this study, we used a simple impregnation method to prepare Fe–Ce–O x catalysts and tested them regarding their low-temperature (200–300 °C) selective catalytic reduction (SCR) of NO using NH 3. We investigated the effects of Fe/Ce molar ratio, the gas hourly space velocity (GHSV), the stability and SO 2/H 2O resistance of the catalysts. The results showed that the FeCe(1:6)O x (Ce/Fe molar ratio is 1:6) catalyst, which has some ordered parallel channels, exhibited good SCR performance. The FeCe(1:6)O x catalyst had the highest NO conversion with an activity of 94–99% at temperatures between 200 and 300 °C at a space velocity of 28,800 h ?1. The NO conversion for the FeCe(1:6)O x catalyst also reached 80–98% between 200 and 300 °C at a space velocity of 204,000 h ?1. In addition, the FeCe(1:6)O x catalyst demonstrated good stability in a 10-h SCR reaction at 200–300 °C. Even in the presence of SO 2 and H 2O, the FeCe(1:6)O x catalyst exhibited good SCR performance. 相似文献
20.
Difficulties in the understanding of photosynthesis by Israeli junior high school students were examined. Thirty‐three students were interviewed and asked about chemical and ecological issues of photosynthesis. Difficulties were found in their understanding of the living body as a chemical substance, lack of knowledge about the chemical elements that compose the living body, and difficulties in understanding that gas (CO 2) is the source of the plant's body. A major problem was the perception of photosynthesis as a type of respiration. Difficulties were also found in students’ understanding of concepts related to the ecosystem, such as the oxygen cycle in nature and autotrophic feeding as the first step of the food chain. Considering these difficulties, we recommend changing the way of teaching these issues. Such a programme is now being tested. 相似文献
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