Promoting effects of Fe_2O_3 to Pt electrocatalysts toward methanol oxidation reaction in alkaline electrolyte

Fe_2O_3 nanorods and hexagonal nanoplates were synthesized and used as the promoters for Pt electrocatalysts toward the methanol oxidation reaction（MOR） in an alkaline electrolyte.The catalysts were characterized by scanning electron microscopy,transmission electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,cyclic voltammetry and chronoamperometry.The results show that the presence of Fe_2O_3 in the electrocatalysts can promote the kinetic processes of MOR on Pt,and this promoting effect is related to the morphology of the Fe_2O_3 promoter.The catalyst with Fe_2O_3 nanorods as the promoter（Pt-Fe_2O_3/C-R） exhibits much higher catalytic activity and stability than that with Fe_2O_3 nanoplates as the promoter（Pt-Fe_2O_3/C-P）.The mass activity and specific activity of Pt in a Pt-Fe_2O_3/C-R catalyst are 5.32 A/mgpt and 162.7 A/m^2_（Pt）,respectively,which are approximately 1.67 and 2.04 times those of the Pt-Fe_2O_3/C-P catalyst,and 4.19 and 6.16 times those of a commercial PtRu/C catalyst,respectively.Synergistic effects between Fe_2O_3 and Pt and the high content of Pt oxides in the catalysts are responsible for the improvement.These findings contribute not only to our understanding of the MOR mechanism but also to the development of advanced electrocatalysts with high catalytic properties for direct methanol fuel cells.

Effect of resveratrol on activation of nuclear factor kappa-B and inflammatory factors in rat model of acute pancreatitis

AIM: To observe the effect of resveratrol on nuclear factor Kappa-B (NF-κB) activation and the inflammatory response in sodium taurocholate-induced pancreatitis in rats. METHODS: Seventy-two male SD rats were randomly divided into three groups: sham operation group (control), severe acute pancreatitis (SAP) group, and severe acute pancreatitis group treated with resveratrol (RES). A SAP model was established by injecting 4% sodium taurocholate 1 mL/kg through puncturing the pancreatic duct. In Res group, Res was given at 30 mg/kg b.m. intraperitoneally after the SAP model was successfully established. Eight animals from each group were sacrificed at 3, 6 and 12 h after modeling. The expression of NF-κB activation of pancreas was detected by irnmunohistochemical staining, whereas the levels of TNF-α and IL-8 in pancreatic tissues were estimated by radioimrnunoassay. The pathological changes of pancreas and lungs were examined microscopically. RESULTS: Much less hyperemia, edema, dust-colored necrotic focus and soaps were noticed in pancreas in RES group than in SAP group. In RES group, hemorrhage, exudates and infiltration of inflammatory cells in pancreas and interstitial edema, destruction of alveolar wall in lung were significantly less than in SAP group. In the SAP group, the activation of NF-κB in pancreatic tissues was enhanced significantly at any measure point compared with control group (64.23±10.72% vs 2.56±0.65%, 55.86±11.34% vs 2.32±0.42%, 36.23±2.30% vs 2.40±0.36%,P<0.01), TNF-α, IL-8 were also increased and reached their peak at 6 h and then declined. The activation of NF-κB and the levels of TNF-α and IL-8 in RES group were significantly lower than those in SAP group (P<0.01): activation (52.63±9.45% vs 64.23±10.72%, 40.52±8.40% vs 55.86±11.34%, 29.83±5.37% vs 36.23±2.30%), TNF-α (132.76±15.68 pg/mL vs 158.36±12.58 pg/mL, 220.32±23.57 pg/mL vs 247.67± 11.62 pg/mL, 175.68±18.43 pg/mL vs 197.35±12.57 pg/mL) and IL-8 (0.62±0.21 μg/L vs 0.83±0.10 μg/L, 1.10±0.124 μg/L vs1.32±0.18 μg/L, 0.98±0.16 μg/L vs 1.27±0.23μg/L). CONCLUSION: The activation of NF-KB is involved in the inflammatory response of rats with SAP. Resveratrol could effectively inhibit the expression of NF-κB activation, alleviate the severity of SAP through its anti-inflammatory effects and regulate the inflammatory mediators.

Protective effect of estradiol on hepatocytic oxidative damage

AIM: To examine the protective effect of estradiol on the cultured hepatocytes under oxidative stress. METHODS: Hepatocytes of rat were isolated by using perfusion method, and oxidative stress was induced by a serum-free medium and FeNTA. MDA level was determined with TBA method. Cell damage was assessed by LDH assay. Apoptosis of hepatocytes was assessed with cytoflowmetric analysis. Expression of Bcl-xl in cultured hepatocytes was detected by Western blot. The radical-scavenging activity of estradiol was valued by its ability to scavenge the stable free radical of DDPH. RESULTS: Oxidative stress increased LDH from 168 +/- 25 x 10(-6)IU.cell(-1) to 780 +/- 62 x 10(-6)IU.cell(-1) and MDA(from 0.28 +/- 0.07 x 10(-6)nmol.cell(-1) to 1.35 +/- 0.12 x 10(-6)nmol.cell(-1)) levels in cultured hepatocyte, and estradiol inhibited both LDH and MDA production in a dose dependent manner. In the presence of estradiol 10(-6)mol.L(-1), 10( -7 )mol.L(-1) and 10(-8)mol.L(-1),the LDH levels are 410 +/- 53 x 10(-6)IU.cell(-1) (P【0.01 vs oxidative group), 530 +/- 37 X 10(-6)IU.cell(-1 ) (P【0.01 vs oxidative group), 687+/-42 x 10(-6)IU.cell(-1) (P【0.05 vs oxidative group) respectively, and the MDA level are 0.71+/-0.12 x 10(-6)nmol.cell(-1) (P【0.01 vs oxidative group),0.97+/-0.11 x 10(-6)nmol.cell(-1 )(P【0.01 vs oxidative group) and 1.27+/-0.19 x 10(-6)nmol.cell(-1) respectively. Estradiol suppressed apoptosis of hepatocytes induced by oxidative stress, administration of estradiol(10(-6)mol/L)decreased the apoptotic rate of hepatocytes under oxidative stress from 18.6 +/- 1.2% to 6.5 +/-2.5%, P【0.01. Bcl-xl expression was related to the degree of liver cell damage due to oxidative stress, and estradiol showed a protective action. CONCLUSION: Estradiol protects hepatocytes from oxidative damage by means of its antioxidant activity.

Isothermal Crystallization Kinetics of Microencapsulated Polyethylene Glycol Particles

The microenapsulated polyethylene glycol （PEG） with different molecular weight by a fluidized coating method has been prepared and the crystallization behaviors of PEG particles in three-dimensional confined vohume were investigated by using differential scanning calorimetry （DSC） measurement. The results showed that the width of the crystallization peak of PEG increases and its height gradually diminishes in case that the PEG particles are microencapsulated. Compared with the non-microencapsulated PEG particles, the proportion of the first crystallization peak of microencapsulated PEG particle increases, and that of the second one decreases. The reason for the difference maybe is that the crystallization process of microencapsulated PEG particles is uniform and the crystallization ends when the spherulites touch the wall, thus the opportunity of producing the second crystallization peak was relatively reduced.

DFT Study on the Structure and Racemization Mechanism of 1,1 ＇- Bina phthalene-8,8 ＇-diol

Density functional theory （DFT） was applied to study the ground state geometries and isomerization processes of 1,1＇-binaphthalene-8,8＇-diol. Three isomers, denoted as ISO1, ISO2, and ISO3, were found, distinguished by different orientations of the OH groups, and each OH-orientational isomer has R- and S-enantiomer. The conformational stabilities of these isomers were investigated by tracking the energy change with respect to the ring-to-ring torsion. The inter-conversions between the three OH-orientational S-isomers were found to have quite low barriers owing to the nearly free rotation of OH groups around the O-C single bonds. The S-R enantiomerization of ISO1 and ISO2 can take place through the ring-ring torsion around the C1-C1/ single bond, either in the anti-rotation manner or in the syn-rotation manner. The barriers of the anti routes are lower than those of the corresponding syn routes by 87.95 and 75.04 kJ/mol. For the S-R enantiomerization of ISO3, only the anti route was found. The barriers for the anti route enantiomerizations of ISO1, ISO2, and ISO3 are 119.61, 120.43, and 121.59 kJ/mol, respectively. A parallel reaction mechanism via three anti enantiomerization routes was proposed for the racemization of 1,1＇-binaphthalene-8,8＇-diol.

Grapefruit-seed extract attenuates ethanol-and stress-induced gastric lesions via activation of prostaglandin, nitric oxide and sensory nerve pathways

AIM： Grapefruit-seed extract （GSE） containing flavonoids, possesses antibacterial and antioxidative properties but whether it influences the gastric defense mechanism and gastroprotection against ethanol- and stress-induced gastric lesions remains unknown. METHODS： We compared the effects of GSE on gastric mucosal lesions induced in rats by topical application of 100% ethanol or 3.5 h of water immersion and restraint stress （WRS） with or without （A） inhibition of cyclooxygenase （COX）-1 activity by indomethacin and rofecoxib, the selective COX-2 inhibitor, （B） suppression of NO-synthase with L-NNA （20 mg/kg ip）, and （C） inactivation by capsaicin （125 mg/kg sc） of sensory nerves with or without intragastric （ig） pretreatment with GSE applied 30 min prior to ethanol or WRS. One hour after ethanol and 3.5 h after the end of WRS, the number and area of gastric lesions were measured by planimetry, the gastric blood flow （GBF） was assessed by H2-gas clearance technique and plasma gastrin levels and the gastric mucosal generation of PGE2, superoxide dismutase （SOD） activity and malonyldialdehyde （MDA） concentration, as an index of lipid peroxidation were determined. RESULTS： Ethanol and WRS caused gastric lesions accompanied by the significant fall in the GBF and SOD activity and the rise in the mucosal MDA content. Pretreatment with GSE （8-64 mg/kg i g） dose- dependently attenuated gastric lesions induced by 100% ethanol and WRS; the dose reducing these lesions by 50% （ID50） was 25 and 36 mg/kg, respectively, and this protective effect was similar to that obtained with methyl PGE2 analog （5 μg/kg i g）. GSE significantly raised the GBF, mucosal generation of PGE2, SOD activity and plasma gastrin levels while attenuating IVlDA content. Inhibition of PGE2 generation with indomethacin or rofecoxib and suppression of NO synthase by L-NNA or capsaicin denervation reversed the GSE-induced protection and the accompanying hyperemia. Cotreatment of exogenous calcitonine gene-related peptide （CGRP） with GSE restored the protection and accompanying hyperemic effects of GSE in rats with capsaicin denervation. CONCLUSION： GSE exerts a potent gastroprotective activity against ethanol and WRS-induced gastric lesions via an increase in endogenous PG generation, suppression of lipid peroxidation and hyperemia possibly mediated by NO and CGRP released from sensory nerves.

Estradiol-17β protects against hypoxia-induced hepatocyte injury through ER-mediated upregulation of Bcl-2 as well as ER-independent antioxidant effects

Although many previous studies have suggested that estrogen functions as a cytoprotective agent under oxidative stress conditions, the underlying mechanism by which this effect is exerted remains to be elucidated. This study assessed the effects of estradiol-17β （E2） （10^-8s M） on hypoxia-induced cell injury and its related signaling in primary cultured chicken hepatocytes. Hypoxic conditions were found to augment the level of DNA damage and to reduce cell viability and the level of [^3H]-thymidine incorporation, and these phenomena were prevented through treatment with E2. Hypoxia also increased caspase-3 expression, but showed no evidence of an influence on the expression of Bcl-2. However, E2 induced an increase in the level of Bcl-2 expression under hypoxic conditions and reduced the level of caspase-3 expression. The effects of E2 on Bcl-2 and caspase expression were blocked by ICI 182780 （E2 receptor （ER） antagonist, 10＂7 M）. In addition, hypoxia resulted in an increase in the intracellular reactive oxygen species （ROS） generated. These effects were blocked by E2, but not by E2-BSA and ICI 182780. Hypoxia also activated p38 mitogen-activated protein kinase （MAPK）, c-JUN N-terminal kinase/stress-activated protein kinase （JNK/SAPK） and nuclear factor-kB （NF-kB）. These effects were blocked by E2, but not by ICI 182780. The inhibition of p38 MAPK and JNK/SAPK blocked NF-kB activation. In conclusion, E2 was found to protect against hypoxia-induced cell injury in chicken hepatocytes through ER-mediated upregulation of Bcl-2 expression and through reducing the activity of ROS-dependent p38 MAPK, JNK/ SAPK and NF-kB.

Study on Synergy Effect in Dimethyl Ether Synthesis from Syngas

Influence of reaction temperature, pressure and space velocity on the direct synthesis of dimethyl ether (DME) from syngas is studied in an isothermal fixed-bed reactor. The catalyst is a physical mixture of C301 copper-based methanol (MeOH) synthesis catalyst and ZSM-5 dehydration catalyst. The experimental results show that the chemical synergy between methanol synthesis reaction and methanol dehydration reaction is evident. The conversion of carbon monoxide is over 90%.

Treatment of oil/water emulsion by polyethylene glycol ultrafiltration membrane

Polyethylene glycol(PEG) membranes with different molecular mass cut-offs were used to treat oil/water emulsion, and the effects of experimental conditions including pressure, temperature and different opera- ting modes on permeate flux and removal rate of chemical oxygen demand (COD_ Cr) were studied. The results show that the permeate flux of ultrafiltration membrane is influenced by pressure and temperature; practical pressure is chosen to be 0.30.7MPa for the PEG with molecular mass cut-offs of 8000 and 0.71.0 MPa for the PEG with molecular mass cut-offs of 2500; and the practical temperature is chosen to be 2532℃. Different operating modes of ultrafiltration also influence the permeate flux and removal rate of COD_ Cr. The ultrafiltration membrane of intermittent cross-flow operating mode is easier to be influenced by blocky polarization and contamination than that of sequential cross-flow operating mode. Removal rate of COD_ Cr in intermittent cross-flow and sequential cross-flow condition can be maintained at about 93%.

Theoretical Studies on Interaction Between Methanol and Functionalized Single-Walled Carbon Nanotubes

We study the adsorption of a methanol molecule on single-walled carbon nanotubes （SWCNTs） with various diameters and chiral angles by using the density functional theory based calculations. We find that methanol prefers to be adsorbed physically on the exterior surface of chiral nanotubes in comparison to the armchair and zigzag tubes with binding energy of about -2.76 kcal/mol, which is consistent with recent experimental and theoretical investigation results. We further consider the adsorption of methanol on the exterior surface and edge site of functionalized SWCNTs. The obtained results indicate that the binding energy of methanol is significantly increased for adsorption on the sidewall of functionalized nanotubes. It is also found that the adsorption of methanol at the edge site of both functionalized and pristine SWCNT is remarkably different （chemisoption process） in comparison to the exterior sidewall of the tubes. Furthermore, the electronic structures and Mulliken charge population of the considered complexes at their ground state are discussed within the context.

Activity of Catalyst for Liquid Phase Methanol Synthesis

the effects of reduction procedure, reaction temperature andcomposition of feed gas on the activity of a CuO-ZnO-Al_2O_3 catalystfor liquid phase methanol synthesis were studied. An optimizedprocedure different from conventional ones was developed to obtainhigher activity and better stability of the catalyst. Both CO andCO_2 in the feed gas were found to be necessary to maintain theactivity of catalyst in the synthesis process. Reaction temperaturewas limited up to 523 K, otherwise the catalyst will be deactivatedrapidly.

Adiabatic correction for the esterification of acetic anhydride by methanol via accurate kinetics

In the field of adiabatic correction for complex reactions,a simple one-stage kinetic model was used to estimate the real reaction kinetics.However,this assumption simplified the real process,inevitably generated inaccurate or even unsafe results.Therefore,it was necessary to find a new correction method for complex reactions.In this work,esterification of acetic anhydride by methanol was chosen as an object reaction of study.The reaction was studied under different conditions by Reaction Calorimeter(RC1).Then,Thermal Safety Software(TSS)was used to establish the kinetic model and estimate the parameters,where,activation energies for three stages were67.09,81.02,73.77 kJ?mol^(-1)respectively,and corresponding frequency factors in logarithmic form were 16.05,19.59,15.72 s^(-1).In addition,two adiabatic tests were performed by Vent Sizing Package2(VSP2).For accurate correction of VSP2 tests,a new correction method based on Enhanced Fisher method was proposed.Combined with kinetics,adiabatic correction of esterification reaction was achieved.Through this research,accurate kinetic parameters for a three-step kinetic model of the esterification reaction were acquired.Furthermore,the correlation coefficients between simulated curves and corrected curves were 0.976 and 0.968,which proved the accuracy of proposed new adiabatic correction method.Based on this new method,conservative corrected results were able to be acquired and be applied in safety assessment.

Transport Process of Isopropanol Aqueous Solution by Pervaporation

To study the transport process of isopropanol aqueous solution by pervaporation, the transport model of isopropanol and that of water at 323 K in polyvinyl alcohol(PVA) membrane were obtained in this paper. Theoretical predictions agreed well with the experimental results. The interactional parameter between water and PVA membrane is less than that between isopropanol and PVA membrane, which shows that water is preferentially dissolved in PVA membrane. The plasticizing coefficient and diffusion coefficient at infinite dilution of water are larger than those of isopropanol, which shows that the dissolution and permeation in PVA membrane of water are greater than those of isopropanol. Both the interactional parameter between water and isopropanol in the membrane and that in feed rise with the increase of isopropanol content in feed, which shows that the larger isopropanol content is, the higher selectivity of the membrane is and the more remarkable separation effect of pervaporation is.

CATALYSIS OF POLYSTYRENE N-HYDROXYL SULFONAMIDE FOR ESTERIFICATION OF BUTANOL WITH ACETIC ANHYDRIDE

Polystyrene N-hydroxyl sulfonamide resin 1 was prepared and used to catalyze the esterification of n-butanol and acetic anhydride. The mechanism of catalytic esterification proved by IR spectra of the resins was found that O-H and N-H of the N-hydroxyl sulfonamide resin reacted with the acetic anhydride respectively to form the active intermediate polystyrene N,O-diacetyl sulfonamate which was cleaved by n-butanol to produce butyl acetate. The catalytic esterification by resin 1 was in good agreement with the kinetic model of 揵i-bi-ping-pong?mechanism.

Enrichment of Resveratrol in Wine through a New Vinification Procedure

Sulphur dioxide is used in the vinification process as an antimicrobial agent, but it is also considered as an important risk factor for liver diseases. Stilbenes have inhibitory effects on the growth of lactic acid bacteria strains isolated from wine. The authors investigated the viability of obtaining free-SO2 resveratrol-enriched red wines. Substitution of sulfite （7 g/100kg） for resveratrol （150 mg/L and 300 mg/L） in the vinification process did not change the basic physical and chemical properties of wine or its sensorial profile To the best of the authors＇ knowledge this is the first time that this type of vinification procedure is reported.

Allelopathic Effects of Aqueous and Ethanolic Leaves Extracts of Schinus molle L. under Different Kinds of Pruning

Secondary metabolites produced by plants can be used in popular medicine, as well they can interact with plants and other organisms, in which case they are called allelochemicals and influence the neighboring ecosystem. This work aimed to evaluate the allelopathic effects of Schinus molle L. species widely used in reforestation and urban afforestation. Therefore, leaves of S. Molle were collected from different populations located at Alfenas and Nepomuceno in Minas Gerais, Brazil. Cypselae of lettuce （Lactuca sativa L.） were germinated in biochemical oxygen demand （BOD） chamber at 25 ℃ with a photoperiod of 12 h under different extracts concentrations. The experiment was performed in factorial design （2 × 4） with two kinds of extracts （aqueous and ethanol） and four concentrations （2.5, 5, 10 and 20 mg/mL） in randomized blocks. The variables analyzed were germination （%）, germination speed index （GS1）, % of normal seedlings, root length, fresh biomass and dry biomass. Changes in the cell cycle in meristematic cells of the used model were also evaluated. Concentration-dependent effect on all parameters was observed, with the exception of dry biomass exposed to ethanol extract. The root elongation parameter was different between the extracts even in lower concentrations, thus indicating that this is the most sensitive parameter of this species. Toxic effect from S. rnolle extracts was observed in all parameters regardless the kind of pruning management or method of extraction （water or ethanol）.

Antioxidant Activity and Anti-Hyperglycemic Effect of Lagenaria Siceraria Fruit Extract

Lagenaria siceraria （Molina） Standl., known as bottle gourd is widely available throughout Vietnam as an edible vegetable. Bottle gourd is a commonly fruit but there are little reports about its biological activities. The aim of the present study was to evaluate antioxidant activity and anti-hyperglycemic potential of ethanolic extract of bottle gourd. The ethanolic extract was tested for its antioxidant activity on chelating power, the ferric reducing/antioxidant power assay （FRAP） and the 1, 1-diphenyl-2-picryl-hydrazyl （DPPH） free radical scavenging assay. The results showed that chelating activity was 80.02%, FRAP value was 92.84 μmol Fe^2＋/g and active radical scavenging which showed an IC50 was 49.50 μg/ml. The five different doses of ethanolic extract were treated by oral tolerance to mice body before oral glucose tolerance and blood glucose level was measured using glucose oxidase method. The result indicated that inhibition percentage of ethanolic extract of bottle gourd at the dose of 400 mg/kg in glucose-induced hyperglycemic mice was effectively similar to standard drug glibenclamide. The results obtained indicate that ethanolic extract from bottle gourd is the potential antioxidant and anti-hyperglycemic agent.

Anticancer effect and enhanced chemotherapy potential of resveratrol in human pancreatic cancer cell lines

Objective Gemcitabine, the only approved drug for the treatment of pancreatic cancer, is not very effective. Novel and effective cancer chemopreventive agents are urgently needed. Recently, emerging studies determined resveratrol possessed anticancer effects on various cancer cells. We explored the anticancer effect of resveratrol in pancreatic cancer cells and investigated the involved moleculars of action. We also examined whether resveratrol enhanced antitumor activity of gemcitabine in vitro.Methods Proliferation inhibition was assessed by cell count kit-8 assay. Cell cycle phase distribution and apoptotic cells were measured by flow cytometric analysis. We determined the expression of bcl-2, cyclinD1, and activation of caspases-3 and poly(ADP-ribose) polymerase1 proteins used Western blot analysis.Results Resveratrol inhibited the proliferation of three pancreatic cancer cell lines in a dose dependent fashion, and induced accumulation of cells at the G1 phase as well as apoptosis. Our data also demonstrated that resveratrol enhanced gemcitabine-induced apoptosis in pancreatic cancer cells. In addition, resveratrol inhibited the expression of cyclinD1, bcl-2, and induced activation of caspase-3 and poly(ADPribose) polymerase1. Conclusion Our results suggested that resveratrol might be not only a potential regimen, but also an effective chemosensitizer for the chemotherapy of pancreatic cancer.

纳米氧化铈在醇水混合溶液中的分散行为

通过沉降实验结合分光光度计、透射电镜等手段,考察了纳米氧化铈在不同比例醇水混合溶液(包括无水乙醇和纯水)中的超声分散性和悬浮稳定性;同时,测量了其在不同比例醇水混合溶液中的Zeta电位,并初步探讨了其分散机制。研究表明,随着醇水混合溶液中乙醇含量的减小,纳米氧化铈的超声分散性和悬浮稳定性均呈现出先升后降的规律;当乙醇含量为40%(体积分数)时,纳米氧化铈的超声分散性和悬浮稳定性均达到最好,其分散率为52.7%,且静置10天后的沉降率也仅为20.2%;此外,在该体系中纳米氧化铈保持其初始粒径的能力较强。纳米氧化铈在醇水混合溶液中的分散不遵守双电层理论,而与分散介质对颗粒的溶剂化作用有关。