Regulation of the NADH supply by nuoE deletion and pncB overexpression to enhance hydrogen production in Enterobacter aerogenes

In this study, seven mutants from E. aerogenes IAM1183 wildtype were constructed via different strategies including deletion of lactate dehydrogenase, disruption of NADH dehydrogenase gene nuoE, overexpression of pncB and a combination of both to regulate of the NADH supply to enhance hydrogen production. Compared with the parental strain, the hydrogen yields of the strains IAM1183-E, IAM1183-L and IAM1183-EL increased by 23.3, 81.7 and 97.9%, respectively. When the pncB gene was overexpressed, the hydrogen yield of IAM1183/P, IAM1183-E/P, IAM1183-L/P and IAM1183-EL/P increased by 39.0, 6.5, 5.9, and 5.1% compared with the respective original knockout strains. Among them, the total hydrogen yield of strain IAM1183-EL/P with highest production efficiency was 58% higher than IAM1183. Further metabolite analysis indicated that the knockout of nuoE and ldhA, combined with the overexpression of pncB, resulted in a redistribution of the metabolic fluxes in E. aerogenes, which led to an improvement of the hydrogen yield.     

氮源和磷源对金铁锁毛状根悬浮培养的影响

以生物量和总皂苷两个参数为指标,研究了氮源(NH+4,NO-3)与磷源(PO3-4)浓度对金铁锁毛状根悬浮培养过程中的影响。培养基中NH+4与NO-3的浓度比为1∶2时,毛状根生物量和总皂苷的收获量都达到最高值,PO3-4的浓度在6.25mmol/L时具有同样的效果;毛状根对培养液中NO-3和PO3-4吸收利用与其生长周期基本一致,它们的含量在20d左右下降到最低;综合考虑,氮源和磷源的最佳组合为NH+410mmol/L,NO-320mmol/L,PO3-46.25mmol/L。     

Pro-oxidant activity of nickel (II) pyridoxal complexes. Synthesis,characterization and peroxidase activity assays

The synthesis of Ni (II) complexes with pro-oxidant applications has demonstrated many advantages, such as accelerated reactions, solution stability and with high selectivity reactions. In this work we describe the synthesis, characterization and structural analysis of nickel ([(Ni)(C₃₀H₂₈N₄O₄S₂)]);([(Ni)(C₃₁H₃₀N₄O₄S₂)]) and ([(Ni)(C₃₃H₃₇N₄O₄S₂)]·DMF — complex 3) complexes with ligands obtained from the condensation of pyridoxal and aryl-thiol amines and their application as a pro-oxidant in the reaction of the phenol-aminoantipyrine adduct. The complexes show variation in carbon spacers between pyridoxal molecules: ethane, propane and butane. It was found that the spacer two carbons containing the most significant as the pro-oxidant activity.     

An Au-nanoparticle decorated Sr0·76Ce0·16WO4 photocatalyst for H2 evolution under visible-light irradiation

Photocatalytic production of H₂ from water based on semiconductors is a process without the consumption of fossil energy. The development of ideal photocatalyst is a challenge that limited the application of photocatalytic technology. Here, we report a stable Sr_0·76Ce_0·16WO₄ photocatalyst for H₂ evolution under visible-light irradiation, which was synthesized via a simple high-temperature solid-state method. The composition and crystal structure of this photocatalyst was identified by X-ray Diffraction, transmission electron microscope, and X-ray photoelectron spectroscopy. The scanning electron microscopy image indicates the sample compose of micrometer particles. The bandgap of the compound was estimated to be 3.18 eV, which is significantly smaller than that of pristine SrWO₄ (4.87 eV) by the incorporation of Ce³⁺. In this experiment, the nanosized Au cocatalyst was loaded on the photocatalyst via the photodeposition method to improve the photocatalytic performances. Photocatalytic experiments revealed that photocatalytic H₂ evolution rates of Sr_0·76Ce_0·16WO₄-1.5Au sample are 45.5 μmol/h/g and 28.7 μmol/h/g in 5 vol% triethanolamine aqueous solution under simulated sunlight and visible-light irradiation, respectively, which are 1.44 times and 4.63 times higher than the cocatalysts-free one. Moreover, the apparent quantum yield of Sr_0·76Ce_0·16WO₄-1.5Au is 0.09% at 450 nm.     

多孔二氧化钛吸附刚果红

以异丙醇钛为前体,十二烷胺为模板剂,采用配体辅助模板法合成高比表面积多孔二氧化钛材料,利用氮气吸附对其孔径性质进行分析。通过静态吸附实验研究了多孔二氧化钛对刚果红的吸附行为,考察了吸附时间、温度、搅拌速度、吸附剂用量和初始浓度对刚果红吸附效果的影响。分别在相关条件下,结果表明：当吸附时间为30min时,脱除率达98%以上;吸附温度为45℃时,脱除率可达98%;摇床转速为160r/min时,脱除率达到最大;当吸附剂使用量为0.10g时,脱除率能够达到98%左右,已能够满足应用要求;多孔二氧化钛吸附刚果红的吸附量与刚果红初始浓度成正比。     

铜的电化学腐蚀过程的红外光谱电化学及量子化学方法研究

    设计了一种超薄层红外光谱电化学池,对铜电极的电化学腐蚀过程的现场监测表明,该电解池有较好的电化学性质和红外光谱响应性;铜电极在1.0 mol/L KCl溶液中的电化学腐蚀过程伴随铜的氯化物生成. 以量子化学方法（ab initio 和arguslab）计算软件对形成的化合物及其红外光谱进行了理论计算.结果表明,在KCl支持电解质水溶液中,铜氧化生成的铜（I）离子易与氯离子形成较稳定的三配位化合物,并获得了与实验结果一致的红外光谱.     

青蒿琥酯诱导肿瘤细胞凋亡与抑制存活蛋白表达有关

目的 探讨青蒿琥酯(artesunate, Art)诱导肿瘤细胞凋亡与存活蛋白(survivin protein)表达的关系。 方法 采用细胞荧光染色、流式细胞术、琼脂糖凝胶电泳法和测定细胞浆Caspase-3 的活性等手段检测肿瘤细胞暴露于不同浓度的Art 时, 对肿瘤细胞凋亡的诱导作用;用RT-PCR、Western Blotting 法,检测不同浓度的Art 作用于肿瘤细胞时, 对survivinmRNA 和survivin 蛋白表达的影响。 结果 HL60 细胞暴露于Art 时, 呈现典型细胞凋亡特征, 如:胞核固缩、形成凋亡小体;凋亡细胞的比例呈浓度依赖性增高;琼脂糖电泳出现明显的“ 梯状” 条带;细胞浆Caspase-3 的活性呈浓度依赖性增高等。RT-PCR 检测表明, A549 细胞暴露于Art 10 和50 g·L^-1 72 h后, survivin mRNA 的表达呈浓度依赖性降低, 对照组、10 和50 mg·L^-1 处理组的survivin 条带和内标GAPDH 条带灰度的比值分别为1.745、0.390 和0.023;Western Blotting 法也检测到Art 抑制Survivin蛋白的表达。 结论 Art诱导肿瘤细胞发生凋亡, 激活Caspase-3 途径, 可能与抑制survivin 基因表达有关。     

黑暗条件下干露对孔石莼生理生化指标的影响

在黑暗条件下干露胁迫处理孔石莼的叶状体,测定其叶绿素a、脯氨酸、可溶性糖、丙二醛的含量以及过氧化物酶（POD）的活性随不同处理时间段（0、0.5、1、2、4、6h）的变化.实验结果显示：孔石莼的各项生理指标与对照组（未经干露处理）相比,除叶绿素a的含量逐渐下降外,其余各项生理指标均出现上升的趋势,其中脯氨酸的含量和POD活性均在4h后急剧升高;经6h胁迫后复水,各指标均有不同程度的恢复.这说明孔石莼对黑暗条件下的干露有一定的适应性,该结果可为孔石莼干露适应的生理机制提供参考.     

Solar hydrogen evolution over native visible-light-driven Sn3O4

Low-cost semiconductor photocatalysts that can efficiently harvest solar energy and generate H₂ from water or alcohols will be critical to future hydrogen economies. Co-catalyst loading and/or doping of foreign element at host material have been crucial for semiconductor photocatalyst to produce significant H₂ evolution, so far. We synthesized native-visible-light driven Sn₃O₄ photocatalyst, which significantly catalyzed hydrogen evolution from various alcohol solutions under irradiation of visible light (λ > 400 nm), without co-catalyst. The H₂ production reaction proceeded through hydroxyalkyl radical reaction in the methanol solution. The apparent quantum yield was 0.4% for the Sn₃O₄ competitive to that of visible-light-sensitive co-catalyst loaded doped photocatalyst. The enhanced hydrogen evolution is attributed to the desirable band gap and band edge positions (CBM and VBM) of the Sn₃O₄ for H₂ production in visible light, which would originate from atomically layered structure of Sn₃O₄. The Sn₃O₄ material is good promising photocatalyst for solar hydrogen production from alcohols.     

Catalytic Mechanism of Short Ethoxy Chain Nonylphenol Dehydrogenase Belonging to a Polyethylene Glycol Dehydrogenase Group in the GMC Oxidoreductase Family

Ethoxy (EO) chain nonylphenol dehydrogenase (NPEO-DH) from Ensifer sp. AS08 and EO chain octylphenol dehydrogenase from Pseudomonas putida share common molecular characteristics with polyethylene glycol (PEG) dehydrogenases (PEG-DH) and comprise a PEG-DH subgroup in the family of glucose-methanol-choline (GMC) oxidoreductases that includes glucose/alcohol oxidase and glucose/choline dehydrogenase. Three-dimensional (3D) molecular modeling suggested that differences in the size, secondary structure and hydropathy in the active site caused differences in their substrate specificities toward EO chain alkylphenols and free PEGs. Based on 3D molecular modeling, site-directed mutagenesis was utilized to introduce mutations into potential catalytic residues of NPEO-DH. From steady state and rapid kinetic characterization of wild type and mutant NPEO-DHs, we can conclude that His465 and Asn507 are directly involved in the catalysis. Asn507 mediates the transfer of proton from a substrate to FAD and His465 transfers the same proton from the reduced flavin to an electron acceptor.