Biohydrogen Production by Mesophilic Anaerobic Fermentation of Glucose in the Presence of Linoleic Acid

In this work, linoleic acid (LA), a long chain fatty acid bearing 18 carbons and two double bonds, inhibited hydrogen consumption in a mixed anaerobic culture acclimated to glucose. At pH = 7.6, a metabolic shift from methane to hydrogen formation was observed in cultures maintained at 37°C and fed 5,000?mg?L?1 glucose in the presence of 500–2,000?mg?L?1 LA. The hydrogen yield increased with increasing LA levels while the quantity of methane decreased. The major volatile fatty acids produced were acetate and butyrate with greater levels observed in cultures fed with LA. Acetate, butyrate, and hydrogen accumulation suggests inhibition of aceticlastic methanogens, hydrogenotrophic methanogens, and butyrate degrading microorganisms, respectively, in the presence of LA. A maximum hydrogen yield of 1.71±0.22?mole?mole?1 glucose was observed only when glucose was reinjected into cultures receiving 2,000?mg?L?1 LA plus 5,000?mg?L?1 glucose.     

Diverting Electron Fluxes to Hydrogen in Mixed Anaerobic Communities Fed with Glucose and Unsaturated C18 Long Chain Fatty Acids

Hydrogen (H2) production was maximized and methane (CH4) formation was minimized in a mixed anaerobic culture which was maintained at 21°C and fed glucose plus unsaturated long chain fatty acids (LCFAs). The initial pH in the batch reactors was 7.8±0.2. The two LCFAs under consideration included linoleic acid (LA) (two C=C bonds) and oleic acid (OA) (one C=C bond). Hydrogen production was observed when glucose was injected on Day 0 and again after Day 4. The H2 yield in cultures fed LA was less than those receiving OA. The H2 yield reached a maximum of approximately 1.1?mol?H2?mol?1 glucose when the LA level was 2,000?mg?L?1. In the case of OA, a maximum yield of 1.3?mol?H2?mol?1 glucose was attained with 2,000?mg?L?1. The inhibition caused by the addition of LA or OA diverted a fraction of electrons toward proton reduction. Under maximum H2 production conditions in the LA fed cultures the acetate production pathway was repressed, while in cultures fed OA the acetate pathway was dominant. The amount of CH4 produced decreased with increasing H2 production and the major volatile fatty acids detected were acetate, propionate and butyrate. Small quantities of formate were detected only in cultures fed LA after the first glucose injection. As the LCFA concentration increased, the initial glucose degradation rate decreased.     

Luminol-Based Enhanced Chemiluminescence Assay for Quantification of Peroxidase and Hydrogen Peroxide in Aqueous Solutions: Effect of Reagent pH and Ionic Strength

The effect of reagent pH and ionic strength was evaluated on the horseradish peroxidase (HRP)-luminol-p-iodophenol enhanced chemiluminescence assay. This assay was optimized for HRP and H2O2 quantification during enzyme-mediated remediation of groundwater or wastewater contaminated with phenolic chemicals. The maximum chemiluminescence intensity (ICLmax) and total area under the chemiluminescence intensity profiles were measured as a function of p-iodophenol concentration, reagent solution pH, and reagent ionic strength. ICLmax values were optimum at pH 8.5 and increased linearly with reagent ionic strength. Optimum chemiluminescence enhancement was produced at a p-iodophenol concentration of 0.3 mM under the reaction conditions. ICLmax values were linearly correlated with HRP and H2O2 concentrations within the ranges of 0.1–1 activity units/mL and 0.1–1 mM, respectively. Results indicate that the HRP-luminol-p-iodohenol enhanced chemiluminescence assay has a potential to be used for quantification of HRP activity and H2O2 concentration in aqueous solutions encountered in groundwater remediation or wastewater treatment scenarios.     

In Situ Source Treatment of Cr(VI) Using a Fe(II)-Based Reductant Blend: Long-Term Monitoring and Evaluation

The long-term effectiveness of an FeSO4+Na2S2O4 reductant solution blend for in situ saturated zone treatment of dissolved and solid phase Cr(VI) in a high pH chromite ore processing solid waste fill material was investigated. Two field pilot injection studies were conducted that showed sustained treatment of Cr(VI) over evaluation periods of more than 1,000 days. No well or aquifer formation clogging was observed during injection although treatment was limited to the pore volume displacement radius of the injected reductant. Analysis of posttreatment core samples suggested >85% treatment effectiveness of solid phase Cr(VI), whereas lab tests suggested treatment of the solid phase Cr(VI) can be complete provided the chromite ore processing solid waste sediments are sufficiently dosed with the reductant. The sustained treatment of dissolved phase Cr(VI) migrating through the treatment zones for more than 1,000 days following injection provided strong evidence of a residual treatment capacity having been imparted to the formation solids. Scanning electron microscopy–energy dispersive x-ray spectroscopy analyses of posttreatment core samples indicated that much of the Cr(VI) may be removed through the formation of a Cr-bearing precipitate, possibly a complex carbonate, characterized by an Fe:Cr molar ratio of roughly 1:1.     

特厚临氢设备用钢12Cr2Mo1R(SA387Gr.22Cl.2)的试制简

 介绍了特厚临氢设备用12Cr2Mo1R(HIC)钢板的生产工艺和技术指标,详细研究了钢板热处理工艺与组织对模拟焊后热处理和回火脆化倾向等性能的关系。以118mm厚钢板为例,给出了化学成分及力学性能结果,结果表明该特厚临氢设备用12Cr2Mo1R钢板成分均匀、杂质元素含量低、综合力学性能优良、回火脆化敏感性低。     

修饰聚合物盐水液-固萃取体系分离钪(Ⅲ)和镨(Ⅲ)的研究

究了Sc和Pr在聚乙二醇 亚氨基二乙酸 (简称PEG IDA)混合Tween 80 盐 水液 固萃取体系中的分配行为 ,讨论了修饰物用量、萃取酸度、吐温用量及分相盐种类和浓度对其萃取率的影响 ,筛选出最佳萃取分离条件 ,控制萃取酸度 ,实现了Sc和Pr的分离。并用pH电位法在 3 0℃的 0 .1mol·L- 1 KNO3溶液中测定了PEG IDA的离解常数以及PEG IDA与Sc和Pr形成的配合物的稳定常数 ,研究了稳定常数与稀土在PEG IDA修饰聚合物 盐 水液 固亲和萃取体系中分配行为的关系 ,并据此对该体系富集分离稀土的机制进行了初步探讨。结果表明 :Sc和Pr是通过与PEG IDA形成配合物而被萃入固相的。     

用钛白废酸处理某铂钯矿及酸浸液综合利用研究

硫酸法钛白生产中产生大量高浓度的废硫酸，必须治理，否则将对环境造成巨大污染。云南某铂钯矿是我国迄今为止发现的第一个独立铂钯矿，但由于其矿石的主要脉石为蛇纹石，仅用浮选法难以获得易于冶炼的低镁精矿。采用低酸浸出—浸渣浮选虽可获得MgO质量分数低于3％的优质铂钯精矿，但由于酸耗较高，使得工艺成本较高。利用硫酸法钛白生产中所产生的废硫酸处理铂钯矿石，可获得优质铂钯精矿，而且使废酸得到了利用。酸浸液中的铁、镁可分别回收铁红和轻质氧化镁。矿石中镁的回收率达70％以上，所产轻质氧化镁经检验完全达到国标一等品要求；回收镁的余液还可生产(NH4)2SO4。本工艺不产生新的废渣、废气，尾水可达标排放。     

Effects of Surface-Bound Fe2+ on Nitrate Reduction and Transformation of Iron Oxide(s) in Zero-Valent Iron Systems at Near-Neutral pH

Nitrate reduction in an iron/nitrate/water system with or without an organic buffer was investigated using multiple batch reactors under strict anoxic conditions. Nitrate reduction was very limited (<10%) at near-neutral pH in the absence of the organic buffer. However, nitrate reduction was greatly enhanced if the system: (1) had a low initial pH ( ～ 2–3); (2) was primed with adequate aqueous Fe2+; or (3) was in the presence of the organic buffer. In Cases (1) and (3), nitrate reduction usually was involved in three stages. The first stage was quick, and H+ ions directly participated in the corrosion of iron grains. The second stage was very slow due to the formation of amorphous oxides on the surface of iron grains, while the third stage was characterized by a rapid nitrate reduction concurrent with the disappearance of aqueous Fe2+. Results indicate that reduction of nitrate by Fe0 will form magnetite; Fe2+ (aq.) can accelerate reduction of nitrate and will be substoichiometrically consumed. Once nitrate is exhausted in the system, no more Fe2+ will be consumed. In the presence of nitrate, Fe2+ (aq) will be adsorbed onto the surface of iron grains or iron oxides; the surface-complexed Fe(II) (extracted by acetate with pH = 4.1) might be oxidized and become structural Fe(III), resulting in a steadily increasing ratio of Fe(III)/Fe(II) in the oxides formed. The transformation of nonstoichiometric amorphous iron oxides into crystalline magnetite, a nonpassive oxide, triggers the rapid nitrate removal thereafter.     

新显色剂AAATP的合成及其与钯的显色反应研究

本文报道了新显色剂２－（４－安替比林偶氮）－４－甲基－５－氨基苯膦酸的合成及其在分析上的应用。试验结果表明,在强酸性溶液中,试剂仅与钯形成络合比为１：２的红色可溶性的稳定配合物,其最大吸收波长为５２５ｎｍ,表现摩尔吸光系数为５,５×１０￣４Ｌ·ｍｏｌ￣－１·ｃｍ￣－１,钯浓度在０～３５μｇ／２５ｍｌ范围内遵守比尔定律。试剂对钯具有高选择性,所拟方法简便、快速,不经分离即可直接进行含钯试样的分析,结果满意。     

Independent retrieval of source dimensions: An extension of results by Starns and Hicks (2005) and a comment on the ACSIM measure.

Recently, J. J. Starns and J. L. Hicks (2005) have argued that source dimensions are retrieved independently from memory (see record 2005-15992-004). In their innovative experiment, manipulating the retrievability of 1 source feature did not affect memory for a 2nd feature. Following C. S. Dodson and A. P. Shimamura (2000; see record 2000-08540-012), the authors argue that the source memory measure that Starns and Hicks used (known as the average conditional source identification measure) is vulnerable to a response bias in this particular paradigm, and this may undermine Starns and Hicks's conclusion. Starns and Hicks, however, acknowledged this possibility. The authors substantiate this claim by a simulation and by replicating Starns and Hicks's experiment. In 2 further experiments, the authors use an extended multinomial model to analyze data showing that Starns and Hicks's conclusion holds even if results cannot be attributed to response biases. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preparation of M2B5O9Cl:Eu2+ (M=Sr,Ca) blue phosphors by a facile low-temperature self-reduction method and their enhanced luminescent properties

In this work,through a facile method of low-temperature(only 350 ℃) self-reduction,1D nano-sized M₂B₅O₉CI:Eu²⁺(M=Sr,Ca) blue phosphors with highly efficient performance can be obtained.The crystal structure,morphology and photoluminescence(PL) properties including thermal stability of M₂B₅O₉CI:Eu²⁺(M=Sr,Ca) phosphors were investigated.The M₂B₅O₉CI:Eu²⁺(M=Sr,Ca) phos...     

2-(5-硝基-4-甲基-2-吡啶偶氮)-5-二甲氨基苯胺激光热透镜光谱法测定钴的研究及其应用

在pH 4.0~7.0的HAc-NaAc缓冲介质中,并在50%乙醇存在下,Co(Ⅱ)与新试剂2-(5-硝基-4-甲基-2-吡啶偶氮)-5-二甲氨基苯胺(5-NO₃-4-CH₃-PADMA)反应形成紫红色配合物;钴配合物形成后,当以强酸酸化,提高酸度至1.8 mol/L H₂SO₄介质,可转变为另一种具有较高吸收特性的绿蓝色质子化形体,最大吸收波长位于622 nm处,与所用He-Ne激光器的输出激光波长(632.8 nm)能较好匹配,据此建立了激光热透镜光谱法测定痕量钴的新方法。钴质量浓度在3~100 ng/mL范围内与分析信号呈良好的线性关系,检出限为1.0 ng/mL。常见金属离子不干扰钴的测定,特别是与钴伴生的铁、镍和铜等元素有较高的允许量,150倍量的Fe³⁺和Ni²⁺、5倍量的Cu²⁺等不干扰钴的测定。实验方法应用于矿石中痕量钴的测定,结果与推荐值(原子吸收光谱法测定结果)一致,相对标准偏差在0.46%~1.46%之间。     

"Social influences on the selection of a protein-sufficient diet by Norway rats (Rattus norvegicus)": Correction to Beck and Galef (1989).

Reports an error in "Social influences on the selection of a protein-sufficient diet by Norway rats (Rattus norvegicus)" by Matthew Beck and Bennett G. Galef (Journal of Comparative Psychology, 1989[Jun], Vol 103[2], 132-139). There was a misstatement. On page 137, second column, second paragraph, the sentence that begins on line 7 ought to read as follows: Protected t tests revealed that subjects in the Different Food-Same Place Group gained a significantly smaller percentage of body weight than did subjects in each of the other two groups (LSD = .67, both ps 1989-31944-001.) Investigated effects of interactions between naive and knowledgeable rats (Rattus norvegicus) on selection of a nutritionally adequate diet by the naive. We found that during a 7-day test, isolated rats choosing among 4 foods, 3 of which were protein-deficient and 1 of which was protein-rich, failed to learn to prefer the protein-rich diet and lost weight. Conversely, those rats that interacted with conspecifics trained to eat the protein-rich diet developed a strong preference for that diet and thrived. The authors also found that Ss were more strongly influenced in their diet selection by the flavor of the foods eaten by conspecifics than by the locations where conspecifics fed. The results suggest that social influence may be important in development of adaptive patterns of diet choice by rats (or other dietary generalists) that need to find nutritionally adequate diets in demanding environments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)