Applicable scope of oxygen-reduced air flooding and the limit of oxygen content

The mechanisms of oxygen-reduced air flooding(ORAF)and the explosion limit and the corrosion control approaches were studied based on the pilots of oxygen-reduced air flooding(ORAF)in the Dagang,Changqing and Daqing oil fields in China.On the foundation of indoor investigations and pilots,the explosion limits,oxygen reduction limits and corrosion control approaches were clarified.When the temperature of reservoir is equal to and higher than 120℃,there is a violent reaction between oxygen and crude oil,that means the effect of low temperature oxidation would be fully taken use of to enhance oil recovery by air flooding directly;nitrogen dominated immiscible flooding with oxygen-reduced air should be applied in cases where reservoir temperature is below 120℃ with little oxygen consumption and little heat generated.The oxygen-reduced air flooding is suitable for 3 types of reservoirs:low permeability reservoir,water flooding development reservoir of high water-cut and high temperature and high salinity reservoir.In the process of development,in order to ensure safety,the oxygen reduction limits should be controlled fewer than 10%,while oxygen-reduced air can obviously reduce the corrosion rate of pipes;The surface pipelines and injection wells don’t need to consider about oxygen corrosion with no water,special materials and structure of pipe or corrosion inhibitor can be applied to the surface pipelines and injection wellbores with water.Air/oxygen-reduced air is a low-cost displacement medium and it could be applied in many special conditions of low permeability reservoir for energy supplement,huff and puff and displacement,that means oxygen-reduced air flooding has become the most potential strategic technology in 20 years.

Single NIR Laser-Activated Multifunctional Nanoparticles for Cascaded Photothermal and Oxygen-Independent Photodynamic Therapy

Inconvenient dual-laser irradiation and tumor hypoxic environment as well as limited judgment of treating region have impeded the development of combined photothermal and photodynamic therapies(PTT and PDT).Herein,Bi2Se3@AIPH nanoparticles(NPs)are facilely developed to overcome these problems.Through a one-step method,free radical generator(AIPH)and phase transition material(lauric acid,LA,44-46°C)are encapsulated in hollow bismuth selenide nanoparticles(Bi2Se3 NPs).Under a single 808-nm laser irradiation at the tumor area,hyperthermia produced by Bi2Se3 not only directly leads to cell death,but also promotes AIPH release by melting LA and triggers free radical generation,which could further eradicate tumor cells in hypoxic environments.Moreover,Bi2Se3 with high X-ray attenuation coefficient endows the NPs with high computed tomography(CT)imaging capability,which is important for treating area determination.The results exhibit that Bi2Se3@AIPH NPs possesses 31.2%photothermal conversion efficiency for enhanced PTT,ideal free radical generation for oxygen-independent PDT,and 37.77 HU mL mg?1 X-ray attenuation coefficient for CT imaging with high quality.Most importantly,the tumor growth inhibition rate by synergistic PTT,PDT,and following immunotherapy is 99.6%,and even one tumor disappears completely,which demonstrates excellent cascaded synergistic effect of Bi2Se3@AIPH NPs for the tumor therapy.

Simultaneous anaerobic-aerobic biodegradation of halogenated phenolic compound under oxygen-limited conditions

The successful application of co-immobilized aerobic-anaerobic biomass under limited aeration in wastewater treatment systems would eliminate the problems associated with the intermediates mono-chlorophenol（MCP） and di-chlorophenol（DCP） accumulations. With low initial pentachlorophenol（PCP） concentration, all PCP could be completely removed under oxygen-limited strict anaerobic conditions, and the removal efficiencies with different initial headspace oxygen percentage（IHOP） were not obviously different from each other. While at high initial PCP concentration, under strictly anaerobic conditions PCP and their intermediates were clearly higher than that under other conditions, and produced obvious accumulation, the highest PCP reduction was achieved by the system receiving 30 IHOP, oxygen-limited system also exhibited lower residual TOC concentration and lower concentration of metabolic intermediates MCP and DCP. These results suggested that under strictly anaerobic condition the reductive dechlorination of low chlorinated compounds became rate limiting in the reductive dechlorination pathway, less chlorinated compounds be more amenable to aerobic degradation, and the aerobes of outer layers could function under limited oxygen. The co-immobilized aerobic-anaerobic biomass for methanogenesis under limited-aeration for chlorophenol degradation might be an attractive and efficient alternative for the sequential anaerobic/aerobic system to achieve mineralization of a broad range of recalcitrance highly chlorinated organics and low final TOC concentrations.

Simulation and Experiment for Oxygen-enriched Combustion Engine Using Liquid Oxygen to Solidify CO2

For capturing and recycling of CO2 in the internal combustion engine, Rankle cycle engine can reduce the exhaust pollutants effectively under the condition of ensuring the engine thermal efficiency by using the techniques of spraying water in the cylinder and optimizing the ignition advance angle. However, due to the water spray nozzle need to be installed on the cylinder, which increases the cylinder head design difficulty and makes the combustion conditions become more complicated. In this paper, a new method is presented to carry out the closing inlet and exhaust system for internal combustion engines. The proposed new method uses liquid oxygen to solidify part of cooled CO2 from exhaust system into dry ice and the liquid oxygen turns into gas oxygen which is sent to inlet system. The other part of CO2 is sent to inlet system and mixed with oxygen, which can reduce the oxygen-enriched combustion detonation tendency and make combustion stable. Computing grid of the IP52FMI single-cylinder four-stroke gasoline-engine is established according to the actual shape of the combustion chamber using KIVA-3V program. The effects of exhaust gas recirculation （EGR） rate are analyzed on the temperatures, the pressures and the instantaneous heat release rates when the EGR rate is more than 8%. The possibility of enclosing intake and exhaust system for engine is verified. The carbon dioxide trapping device is designed and the IP52FMI engine is transformed and the CO2 capture experiment is carried out. The experimental results show that when the EGR rate is 36% for the optimum EGR rate. When the liquid oxygen of 35.80-437.40 g is imported into the device and last 1-20 min, respectively, 21.50-701.30 g dry ice is obtained. This research proposes a new design method which can capture CO2 for vehicular internal combustion engine.

Production of aryl oxygen-containing compounds from catalytic pyrolysis of bagasse lignin over LaTixFe1xO3

A new approach,named production of aryl oxygen-containing compounds from the catalytic pyrolysis of bagasse lignin(BL) over perovskite oxide,was proposed,A series of LaTixFe1-xO3(LTF-x) samples were prepared by the solid state reaction method.The crystal phase and morphology of LTF-x were characterized by XRD and SEM respectively.Catalytic pyrolysis performance of LTF-x was performed by TG-DTG and the distribution patterns of gaseous,liquid and solid products from BL was investigated using a fixed-bed micro-reactor.The optimal reaction conditions were determined:the pyrolysis temperature was 600℃,the mass ratio of mBL:mLTF-0.2 was 3:1,the veloeity of earrier gas was 100 ml·min-1.The gaseous produets were mainly eomposed of CO2,CO,CH4 and CnHm(n=2-4,m=2 n+2 or m=2 n),The main aryl oxygen-containing compounds in liquid products were phenolics,guaiacols,syringols and phenylates,the rest were benzenes,furans,esters and carboxylic acid.The total contents of aryl oxygencontaining compounds were from 62% up to more than 72% under the action of the perovskite.Moreover,the LTF-0.2 sample had nice regenerability.

Si _3O cluster:excited properties under external electric field and oxygen-deficient defect models

This paper investigates the excited states of Si3O molecule by using the single-excitation configuration interaction and density functional theory. It finds that the visible light absorption spectrum of Si3O molecule comprises the yellow and the purple light without external electric field, however all the visible light is included except the green light under the action of external electric field. Oxygen-deficient defects, which also can be found in Si3O molecule, have been used to explain the 1 from silicon-based materials but the microstructures of the materials are still uncertain Our results accord with the experimental values perfectly, this fact suggests that the structure of Si3O molecule is expected to be one of the main basic structures of the materials, so the oxygen-deficient defect structural model for Si3O molecule also has been provided to research the structures of materials.

Perovskite-type oxygen-permeable membrane BaCo_(0.7)Fe_(0.2)Nb_(0.1)O_(3-δ) for partial oxidation of methane in coke oven gas to hydrogen

Perovskite-type oxygen-permeable membrane reactors of BaCo0.7Fe0.2Nb0.1O3-δ （BCFNO） packed with Ru-based catalyst had high oxygen permeability and could be used for hydrogen production by partial oxidation of methane in coke oven gas （COG）. At 1173 K, 94% of methane conversion, 85% of H2 selectivity, 107% of CO selectivity, and as high as 15.4 mL·cm^-2·min^-1 of oxygen permeation flux were obtained. The BCFNO membrane itself had poor catalytic activity to partial oxidation of CH4 in COG. During continuous operation for 70 h at 1173 K, no degradation of the membrane reaction performance was observed. XRD and SEM characterization also demonstrated that the BCFNO membrane reactor exhibited good stability in partial oxidation of methane in COG.

Expression of cyclinD1 in a rat model of oxygen-induced retinopathy

This study sought to elucidate the correlation between cyclinD1 expression and the emergence of neovascularization in oxygen-induced retinopathy （OIR）. OIR was induced in Sprague-Dawley 7-day-old neonatal rats exposed to hyperoxia （75% O2） for 5 days, and then returned to room air. Adenosine diphosphatase staining showed that the neovascularization started to emerge at rat age of day 14, and reached a peak at day 17, then gradually decreased and resolved by day 26. Immunohistochemical and immunofluorescence staining revealed that cyclinD1 protein expression was seen in the OIR rats at the age of day 12, then gradually increased and returned to normal levels by day 26. These experimental findings demonstrated that the temporal pattern of cyclinD1 protein expression is consistent with the emergence of retinal neovascularization.

IcarisideⅡ alleviates oxygen-glucose deprivation and reoxygenation-induced PC12 celloxidative injury by activating Nrf2 / SIRT3signaling pathway

OBJECTIVE To investigate icariside(ICS)Ⅱ protects against PC12 cel damage induced by oxygen-glucose deprivation and reoxygenation and explore its mechanism.METHODS The oxidative stress injury model was induced by oxygen-glucose deprivation/reoxygenation(OGD/R) 2 h/24 h in PC12 cells.N-acetyl-lcysteine(NAC),a classical anti-oxidant,was used as positive control.Pharmacodynamic experimental study groups as follows:control,control+ICS Ⅱ50 μmol·L^(-1),OGD/R,OGD/R+ICSⅡ 12.5 μmol·L^(-1),OGD/R + ICS Ⅱ 25 μmol·L^(-1),OGD/R + ICS Ⅱ50 μmol·L^(-1),and OGD/R+NAC 100 μmol·L^(-1) groups.Cell viability and lactate dehydrogenase(LDH) leakage rate were measured by MTT assay and LDH ELISA kit,respectively.Moreover,reactive oxygen species(ROS) ELISA kit was used for detection of intracellular ROS generation,Mito-SOX fluorescence staining was used for detecting production of ROS in mitochondria and mitochondrial membrane potential(MMP)was detected by rhodamine 123 dye.In addition,PC12 cells apoptosis was detected by one-step TUNEL assay.Furthermore,the expressions of nuclear factor erythroid 2-related factors(Nrf2),Keap1,HO^(-1),NQO^(-1),silent information regulator 3(SIRT3),IDH2,Bax,Bcl-2 and caspase 3 were detected by Western blotting analysis.RESULTS The results of MTT and LDH assay showed that OGD/R reduced the cell viability and improved LDH release compared with the control or ICSⅡ 50 μmol·L^(-1) alone(P<0.01).Meanwhile,OGD/R not only increased intracellular and mitochondrial ROS generation,but also elevated the fluorescence intensity of TUNEL staining,at the same time,the MMP was declined when challenged by OGD/R.Furthermore,the Western blotting results showed that OGD/R induced the increase in the expression of cytoplasm-Nrf2,Keap1,Bax and cleaved-caspase 3 level,while the decrease in the expression of nucleus-Nrf2,HO^(-1),NQO^(-1),SIRT3,IDH2 and Bcl-2(P<0.05).However,ICS Ⅱ significantly increased the viability of PC12 cells and reduced LDH leakage(P<0.01).Notably,ICS Ⅱ also suppressed ROS generation both in the intracellular and mitochondria,as well as restored MMP.It was also worthy to note that ICS Ⅱ decreased the expressions of cytoplasmNrf2,Keap1,Bax and the level of cleaved-caspase3,whereas,it increased the expressions of nucleus-Nrf2,HO^(-1),NQO^(-1),SIRT3,IDH2 and Bcl-2(P<0.05).CONCLUSION ICSⅡ reduced OGD/Rinduced oxidative damage in PC12 cells under the laboratory conditions,and its underlying mechanism may be related to the regulation of Nrf2/SIRT3 signaling pathway.

Astragalus injection inhibits c-Jun N terminal kinase mRNA expression following oxygen-glucose deprivation and reintroduction in rat hippocampal neurons

BACKGROUND： In studies concerning cell injury induced by cerebral ischemia-reperfusion, current experiments have primarily focused on altered protein levels. In addition, the apoptotic proteins Bax and Bcl-2 have been thoroughly studied with regard to initiating neuronal apoptosis. OBJECTIVE： To establish an in vitro model of oxygen-glucose deprivation and reintroduction in the rat hippocampus to simulate cerebral ischemia-reperfusion injury; to observe c-Jun N-terminal kinase 3 （JNK3） mRNA expression in hippocampal neurons following Astragalus injection; and thus to determine changes in the signaling and downstream pathways of neuronal apoptosis at the cellular and molecular level. DESIGN, TIME AND SETTING： A randomized, controlled, cellular and molecular experiment was performed at the Department of Central Laboratory, Chengde Medical College from February to June 2008. MATERIALS： Astragalus injection, the main ingredient of astragaloside, was purchased from Chengdu Di＇ao Jiuhong Pharmaceutical Manufactory, China. JNK3 mRNA probe and in situ hybridization kit were purchased from Tianjin Haoyang Biological Technology, China, and JNK3 RT-PCR primers were designed by Shanghai Bio-engineering, China. METHODS： Primary cultures of hippocampal neurons derived from Sprague Dawley rats, aged 1 2 days, were established. After 8 days, the hippocampal neurons were assigned to the following interventions： model group, Astragalus group, and vehicle control group, cells were subjected to oxygen-glucose reintroduction after oxygen-glucose deprivation for 30 minutes in sugar-free Earle＇s solution and a hypoxia device, which contained high-purity nitrogen. The normal control group was subjected to primary culture techniques and was not treated using above-mentioned interventions. In addition, the Astragalus and vehicle control groups were treated with Astragalus injection （0.5 g/L raw drug） or sterile, deionized water at 2 hours prior to oxygen-glucose deprivation, respectively. MAIN OUTCOME MEASURES： JNK3 mRNA expression was measured by in situ hybridization and RT-PCR at 0, 0.5, 2, 6, 24, 72, and 120 hours after oxygen-glucose reintroduction. RESULTS： Hippocampal neuronal morphology was normal in the normal control group. Hippocampal neurons exhibited apparent apoptosis-like pathological changes in the model, as well as the vehicle control, groups. The apoptosis-like pathological changes in the hippocampal neurons were less in the Astragalus group. Results from in situ hybridization and RT-PCR showed that JNK3 mRNA expression significantly increased in hippocampal neurons from model group, as well as the vehicle control group, compared with the normal control group （P 〈 0.05）. In addition, JNK3 mRNA expression significantly decreased in hippocampal neurons of the Astragalus group, compared with the model group and vehicle control group （P 〈 0.05）. CONCLUSION： Astragalus injection inhibited apoptosis-related JNK3 mRNA expression following oxygen-glucose deprivation and reintroduction, and accordingly played a role in inhibiting hippocampal neuronal apoptosis.

Structural Characterization and Octanol/water Partition Coefficients(LogP) Prediction for Oxygen-containing Organic Compounds

New descriptors were constructed and structures of some oxygen-containing organic compounds were parameterized. The multiple linear regression（MLR） and partial least squares regression（PLS） methods were employed to build two relationship models between the structures and octanol/water partition coefficients（LogP） of the compounds. The modeling correlation coefficients（R） were 0.976 and 0.922, and the ＂leave one out＂ cross validation correlation coefficients（R（CV）） were 0.973 and 0.909, respectively. The results showed that the structural descriptors could well characterize the molecular structures of the compounds; the stability and predictive power of the models were good.

Role of unc5b in retinal neovascularization in mice with oxygen-induced retinopathy

AIM: To explore the role of unc5b in retinal neovascularization in murine oxygen-induced retinopathy (OIR). METHODS: On postnatal 7 (P7), C57BL/6J mice were exposed to 75% +/- 2% oxygen for 5 days. On postnatal 12 (P12), the mice were brought back to the room air (21% oxygen) to induce retinal neovascularization. Western blot analysis was performed to examine the temporal expression of unc5b in murine retinas. Double staining for unc5b and isolectin B4 were employed to determine the location of unc5b in murine retinas. The effect of unc5b on retinal neovascularization was evaluated by intravitreal injection of unc5b-FC in mice with OIR. Retinal neovascularization was measured by counting neovascular cell nuclei above the internal limiting membrane and by angiography of flat-mounted retinas perfused with fluorescein dextran. o RESULTS: Compared to age-matched normal mice, the expression of unc5b was significantly increased in retinas of OIR mice on P17 and P21. Unc5b was apparently expressed in retinal vessels of OIR while being negative in normal retinal vessels. Retinal neovascularization in eyes injected with unc5b-FC was significantly reduced. CONCLUSION: Unc5b-FC can effectively inhibit retinal neovascularization induced by OIR. It may serve as a powerful and novel therapy for ischemia-induced retinal disease.

Proliferation and Differentiation of Neural Stem Cells Co-Cultured with Cerebral Microvascular Endothelial Cells after Oxygen-glucose Deprivation

Various stem cells, including neural stem cells （NSCs）, have been extensively studied in stroke models, but how to increase neuronal differentiation rate of NSCs remains unresolved, particu- larly in a damaged environment. The purpose of this study was to investigate the effects of cerebral mi- crovascular endothelial cells （CMECs） on the neurogenesis of NSCs with or without oxygen-glucose deprivation （OGD）. The NSCs acquired from primary culture were immunostained to prove cell purity. Survival and proliferation of NSCs were determined after the co-culture with CMECs for 7 days. After removing the CMECs, NSCs were randomly divided into two groups as follows： OGD and non-OGD groups. Both groups were maintained in differentiation culture for 4 days to evaluate the differentiation rate. Mouse embryo fibroblast （MEF） cells co-cultured with NSCs served as control group. NSCs co-cultured with CMECs had an increase in size （on the 7th day： 89.80±26.12 μm vs. 73.08±15.01μm, P〈0.001） （n=12） and number [on the 7th day： 6.33±5.61/high power objective （HP） vs. 2.23±1.61/HP, P〈0.001] （n=12） as compared with those co-cultured with MEF cells. After further differentiation cul- ture for 4 days, NSCs co-cultured with CMECs had an increase in neuronal differentiation rate in OGD and non-OGD groups, but not in the control group （15.16% and 16.07% vs. 8.81%; both P〈0.001） （n=6） This study provided evidence that OGD could not alter the effects of CMECs in promoting the neuronal differentiation potential of NSCs. These findings may have important implications for the development of new cell therapies for cerebral vascular diseases.

Shuxuetong injection protects cerebral microvascular endothelial cells against oxygen-glucose deprivation reperfusion

Shuxuetong injection composed of leech(Hirudo nipponica Whitman) and earthworm(Pheretima aspergillum) has been used for the clinical treatment of acute stroke for many years in China. However, the precise neuroprotective mechanism of Shuxuetong injection remains poorly understood. Here, cerebral microvascular endothelial cells(bEnd.3) were incubated in glucose-free Dulbecco's modified Eagle's medium containing 95% N_2/5% CO_2 for 6 hours, followed by high-glucose medium containing 95% O_2 and 5% CO_2 for 18 hours to establish an oxygen-glucose deprivation/reperfusion model. This in vitro cell model was administered Shuxuetong injection at 1/32, 1/64, and 1/128 concentrations(diluted 32-, 64-, and 128-times). Cell Counting Kit-8 assay was used to evaluate cell viability. A fluorescence method was used to measure lactate dehydrogenase, and a fluorescence microplate reader used to detect intracellular reactive oxygen species. A fluorescent probe was also used to measure mitochondrial superoxide production. A cell resistance meter was used to measure transepithelial resistance and examine integrity of monolayer cells. The fluorescein isothiocyanate-dextran test was performed to examine blood-brain barrier permeability. Real-time reverse transcription polymerase chain reaction was performed to analyze mRNA expression levels of tumor necrosis factor alpha, interleukin-1β, interleukin-6, and inducible nitric oxide synthase. Western blot assay was performed to analyze expression of caspase-3, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, occludin, vascular endothelial growth factor, cleaved caspase-3, B-cell lymphoma 2, phosphorylated extracellular signal-regulated protein kinase, extracellular signal-regulated protein kinase, nuclear factor-κB p65, I kappa B alpha, phosphorylated I kappa B alpha, I kappa B kinase, phosphorylated I kappa B kinase, claudin-5, and zonula occludens-1. Our results show that Shuxuetong injection increases bEnd.3 cell viability and B-cell lymphoma 2 expression, reduces cleaved caspase-3 expression, inhibits production of reactive oxygen species and mitochondrial superoxide, suppresses expression of tumor necrosis factor alpha, interleukin-1β, interleukin-6, inducible nitric oxide synthase mRNA, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1, markedly increases transepithelial resistance, decreases blood-brain barrier permeability, upregulates claudin-5, occludin, and zonula occludens-1 expression, reduces nuclear factor-κB p65 and vascular endothelial growth factor expression, and reduces I kappa B alpha, extracellular signal-regulated protein kinase 1/2, and I kappa B kinase phosphorylation levels. Overall, these findings suggest that Shuxuetong injection has protective effects on brain microvascular endothelial cells after oxygen-glucose deprivation/reperfusion. Moreover, its protective effect is associated with reduction of mitochondrial superoxide production, inhibition of the inflammatory response, and inhibition of vascular endothelial growth factor, extracellular signal-regulated protein kinase 1/2, and the nuclear factor-κB p65 signaling pathway.

Application of oxygen-sensing technology to measure seed quality of Ginkgo biloba

Germination tests are currently the most widely used method to evaluate seed quality of Ginkgo biloba L., but they are time-consuming and labor intensive. Oxygen-sensing technology, based on the principle of fluorescence quenching to detect oxygen and assess seed quality was used to rapidly evaluate seed quality of two varieties (Shandong Tancheng 202 and Zhejiang Dafoshou) of G. biloba from five mother plants. Fifteen samples of three vigor levels were produced by accelerated aging treatments. This process was applied in duplicate. A portable oxygen-sensing detector was employed to measure oxygen content during seed germination in a closed system at 25 A degrees C each day until day 14. Four oxygen metabolism indices were calculated: oxygen consumption index, oxygen consumption rate, critical oxygen concentration, and theoretical germination time (T (GT)). Additionally, we tested laboratory germination and field emergence. The results of a one-way analysis of variance and correlation analysis showed that T (GT) was the candidate index to evaluate seed quality of G. biloba. Therefore, the T (GT) value was used to validate the reliability of oxygen-sensing evaluation for Zhejiang Dafoshou seeds kept under four storage conditions. The trend in the change in oxygen metabolism agreed completely agreement with that of seed germination under all storage conditions. The oxygen-sensing test reliably and rapidly assessed seed quality of G. biloba. The germination rate of Zhejiang Dafoshou was accurately predicted by T (GT).

Activin A prevents neuron-like PC12 cell apoptosis after oxygen-glucose deprivation

In this study, PC12 cells were induced to differentiate into neuron-like cells using nerve growth factor, and were subjected to oxygen-glucose deprivation. Cells were treated with 0, 10, 20, 30, 50, 100 ng/mL exogenous Activin A. The 3-（4,5-dimethyl-2-thiazolyl）-2,5-diphenyl tetrazolium bromide assay and Hoechst 33324 staining showed that the survival percentage of PC12 cells significantly decreased and the rate of apoptosis significantly increased after oxygen-glucose deprivation. Exogenous Activin A significantly increased the survival percentage of PC12 cells in a dose-dependent manner. Reverse transcription-PCR results revealed a significant increase in Activin receptor IIA, Smad3 and Smad4 mRNA levels, which are key sites in the Activin A/Smads signaling pathway, in neuron-like cells subjected to oxygen-glucose deprivation, while mRNA expression of the apoptosis-regulation gene caspase-3 decreased. Our experimental findings indicate that exogenous Activin A plays an anti-apoptotic role and protects neurons by means of activating the Activin A/Smads signaling pathway.

Curcumin pretreatment and post-treatment both improve the antioxidative ability of neurons with oxygen-glucose deprivation

Recent studies have shown that induced expression of endogenous antioxidative enzymes thr- ough activation of the antioxidant response element/nuclear factor erythroid 2-related factor 2 （Nrf2） pathway may be a neuroprotective strategy. In this study, rat cerebral cortical neurons cultured in vitro were pretreated with 10 ktM curcumin or post-treated with 5 pM curcumin, respectively before or after being subjected to oxygen-glucose deprivation and reoxygenation for 24 hours. Both pretreatment and post-treatment resulted in a significant decrease of cell injury as indicated by propidium iodide/Hoechst 33258 staining, a prominent increase of Nrf2 protein expression as indicated by western blot analysis, and a remarkable increase of protein expression and enzyme activity in whole cell lysates of thioredoxin before ischemia, after ischemia, and after reoxygenation. In addition, post-treatment with curcumin inhibited early DNA/RNA oxidation as indicated by immunocytochemistry and increased nuclear Nrf2 protein by inducing nuclear accumulation of Nrf2. These findings suggest that curcumin activates the expression of thi- oredoxin, an antioxidant protein in the Nrf2 pathway, and protects neurons from death caused by oxygen-glucose deprivation in an in vitro model of ischemia/reperfusion. We speculate that pharmacologic stimulation of antioxidant gene expression may be a promising approach to neu- roprotection after cerebral ischemia.

Identification of altered microRNAs in retinas of mice with oxygen-induced retinopathy

AIM: To identify disease-related miRNAs in retinas of mice with oxygen-induced retinopathy(OIR), and to explore their potential roles in retinal pathological neovascularization. METHODS: The retinal miRNA expression profile in mice with OIR and room air controls at postnatal day 17(P17) were determined through miRNA microarray analysis. Several miRNAs were significantly up-and down-regulated in retinas of mice with OIR compared to controls by quantitative real-time reverse transcription-polymerase chain reaction(qRT-PCR). Two databases including Targetscan7.1 and MirdbV5 were used to predict target genes that associated with those significantly altered mi RNAs in retinas of mice with OIR. Gene Ontology(GO) and Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway analyses were also conducted to identify possible biological functions of the target genes. RESULTS: In comparison with room air controls, 3 and 8 miRNAs were significantly up-and down-regulated, respectively, in retinas of mice with OIR. The qRT-PCR data confirmed that mmu-miR-350-3 p and mmu-miR-202-3 p were significantly up-regulated, while mmu-miR-711 and mmu-miR-30 c-1-3 p were significantly down-regulated in mice with OIR compared to controls. GO analysis demonstrated that the identified target genes were related to functions such as cellular macromolecule metabolic process. KEGG pathway analysis showed a group of pathways, such as Wnt signaling pathway, transcriptionalmisregulation in cancer, Mucin type O-glycan biosynthesis, and mitogen-activated protein kinase(MAPK) signaling pathway might be involved in pathological process of retinal neovascularization. CONCLUSION: Our findings suggest that the differentially expressed miRNAs in retinas of mice with OIR might provide potential therapeutic targets for treating retinal neovascularization.

Performance of a tubular oxygen-permeable membrane reactor for partial oxidation of CH_4 in coke oven gas to syngas

A gas-tight BaCo 0.7 Fe 0.2 Nb 0.1 O 3-δ（BCFNO） tubular membrane was fabricated by hot pressure casting.And a membrane reactor with BCFNO tubular membrane and Ag-based sealant was readily constructed and applied to partial oxidation of CH4 in coke oven gas.At 875 ℃,95% of methane conversion,91% of H 2 and as high as 10 ml cm-2·min-1 of oxygen permeation flux were obtained.There was a good match in the coefficient of thermal expansion between Ag-based alloy and BCFNO membrane materials.The tubular BCFNO membrane reactor packed with Ni-based catalysts exhibited not only high activity but also good stability in hydrogen-enriched coke oven gas（COG） atmosphere.

Proprotein convertase 1/3-mediated down-regulation of brain-derived neurotrophic factor in cortical neurons induced by oxygen-glucose deprivation

Brain-derived neurotrophic factor(BDNF)has robust effects on synaptogenesis,neuronal differentiation and synaptic transmission and plasticity.The maturation of BDNF is a complex process.Proprotein convertase 1/3(PC1/3)has a key role in the cleavage of protein precursors that are directed to regulated secretory pathways;however,it is not clear whether PC1/3 mediates the change in BDNF levels caused by ischemia.To clarify the role of PC1/3 in BDNF maturation in ischemic cortical neurons,primary cortical neurons from fetal rats were cultured in a humidified environment of 95%N_2 and 5%CO_2 in a glucose-free Dulbecco's modified Eagle's medium at 37℃for3 hours.Enzyme-linked immunosorbent assays and western blotting showed that after oxygen-glucose deprivation,the secreted and intracellular levels of BDNF were significantly reduced and the intracellular level of PC1/3 was decreased.Transient transfection of cortical neurons with a PC1/3 overexpression plasmid followed by oxygen-glucose deprivation resulted in increased PC1/3 levels and increased BDNF levels.When levels of the BDNF precursor protein were reduced,the concentration of BDNF in the culture medium was increased.These results indicate that PC 1/3 cleavage of BDNF is critical for the conversion of pro-BDNF in rat cortical neurons during ischemia.The study was approved by the Animal Ethics Committee of Wuhan University School of Basic Medical Sciences.