二氧化碳在P^＋／P—Si半导体电极上光电化学还原的研究

1870年,Royer使用Zn电极将CO_2还原为HCOOH。近年来,人们对CO_2在几十种金属电极上的电化学还原进行了深入的研究。但普遍存在的问题是CO_2在金属电极上还原的过电位较大,导致耗电较多。而半导体电极能吸收光能降低CO_2还原的过电位,所以人们对CO_2在半导体电极上的光电还原进行了探讨,使用的光阴极材料有P-GaP,P-GaAs,P-InP,P-CdTe。半导体Si的禁带宽度E_g=1.12eV,     

密集波分复用(DWDM)综述(Ⅰ)

对ＤＷＤＭ 技术的概念、系统构成、特点和支撑技术,以及测试、应用等做了全面的综述     

Rapid Amplification of Uncharacterized Transposon-tagged DNA Sequences from Genomic DNA

Although the entire DNA sequence of the yeast genome has been determined, the functions of nearly a third of the identified genes are unknown. Recently, we described a collection of mutants, each with a transposon-tagged disruption in an essential gene in Saccharomyces cerevisiae. Identification of these essential genes and characterization of their mutant phenotypes should help assign functions to these thousands of novel genes, and since each mutation in our collection is physically marked by the uniform, unique DNA sequence of the transposable element, it should be possible to use the polymerase chain reaction (PCR) to amplify the DNA adjacent to the transposon. However, existing PCR methods include steps that make their use on a large scale cumbersome. In this report, we describe a semi-random, two-step PCR protocol, ST-PCR. This method is simpler and more specific than current methods, requiring only genomic DNA and two pairs of PCR primers, and involving two successive PCR reactions. Using this method, we have rapidly and easily identified the essential genes identified by several of our mutants. ©1997 John Wiley & Sons, Ltd.     

炉水低磷酸盐测定中的还原剂研究

火电厂炉水中低磷酸盐测定多采用磷钼蓝法,但目前磷钼蓝法中使用的还原剂不甚理想。经过大量实验,在传统还原剂抗坏血酸的基础上,加入EDTA二钠盐及乙酸,其混合液作为磷钼蓝法中的还原剂。在λmax=810nm,磷酸盐含量在0．05～1．0mg／L范围内符合朗伯-比尔定律,其检测下限为0．029mg／L,RSD=0．347％,样品回收率为97．3％-104．1％,完全能满足火电厂炉水中低磷酸盐含量的测量。     

基于抛物线拟合的光纤自动对准算法

半导体激光器（LD）与单模光纤（SMF）耦合时,峰值功率搜索算法是实现自动对准的关键.对LD和SMF端面耦合特性进行了分析,进而设计了基于抛物线拟合原理的光纤自动对准算法,给出了算法的具体实现方法.实验证明,与传统的爬山法相比,这种算法由于减少了采样点数而缩短了搜索时间,收敛速度快,从而提高了自动对准的速度.     

戊糖片球菌协同蜂蜜接合酵母LGL-1混合发酵提升黄皮果酒品质的研究

目的 为提升黄皮果酒的的品质。方法 从米香型白酒酒厂的小曲中筛选乳酸菌,以协同蜂蜜接合酵母(Zygosacharomyces mellis,LGL-1)进行果酒酿造。经形态学及分子生物学鉴定、生长测定及顶空固相微萃取偶联气质(HS-SPME-GC-MS)和气相色谱(Gas chromatography,GC)对风味物质进行分析。结果 所筛菌株BJQ-1、CZZX-2和LJQ-1为戊糖片球菌(Pediococcus pentosaceus);三株菌皆能利用葡萄糖和果糖进行生长且葡萄糖/果糖质量比1:1复配糖耐受性约300 g/L,BJQ-1、LJQ-1乙醇耐受性达14% vol,CZZX-2乙醇耐受性达16% vol,即所筛菌株适合复配协同酵母菌进行果酒酿造;当CZZX-2、BJQ-1和LJQ-1分别协同LGL-1进行黄皮果酒酿造时,与对照组相比,戊糖片球菌CZZX-2的强化发酵提升黄皮果酒品质的效果最佳,果酒中挥发性物质的种类由34种增加至41种,果酒中2-苯乙醇、异丁醇及异戊醇含量与对照组相比,分别降低47.8%、48.9%和24.7%,乙酸乙酯含量显著提升614.7%。结论 戊糖片球菌CZZX-2能协同蜂蜜接合酵母LGL-1进行黄皮果酒酿造,达到增酯降醇的目的,提升其品质。本研究可为黄皮果酒的工业化生产提供菌种及一定的理论基础。     

优化球团原料的配矿

为了获得低成本、质量好的球团矿产品,以两种铁精矿粉（低铁高硅磁铁矿和高铁低硅磁铁矿）和一种膨润土为原料,以生球落下强度、抗压强度以及焙烧后成品球团抗压强度为评价指标,在相同造球工艺和膨润土加入量的条件下,研究两种质量不同的铁精矿混合配料造球对球团性能的影响。研究表明,随着低铁高硅矿配比的增加,生球落下强度、抗压强度以及焙烧后成品球团抗压强度均随之降低。通过优化配矿,当低铁高硅矿配比达40%时,生球的落下强度达到3次以上,抗压强度达20N以上,焙烧后抗压强度为3850N,完全满足生产要求。     

常用铁矿粉高温基础性能研究

对常用的13种铁矿粉进行了同化性、液相流动性和粘结相强度等高温基础性能研究,并分析讨论了化学成分等对其高温基础性能的影响.结果表明,铁矿粉的同化性与成分SiO2和MgO含量有关,铁矿粉的液相流动性和粘结相强度与成分SiO2和Al2 O3含量相关,铁矿粉高温基础特性的研究可为后续烧结优化配矿提供借鉴.     

Synthesis and up-conversion luminescence of Yb3 + –Ho3 + co-doped Na(Y1·5Na0·5)F6 nanorods

We present the optical up-conversion (UC) study for Yb^3?+?–Ho^3?+? co-doped Na(Y_1·5Na_0·5)F₆ nanorods synthesized by employing a facile hydrothermal method. Numbers of Ho^3?+? ion up-conversion emissions have been observed under 980 nm infrared diode laser excitation. Three UC emissions of interest, ultraviolet, violet and blue, are specially identified at 359, 387, 418 and 483 nm, corresponding to $^{5}{{G}}^{\prime}_{5}{/}^{3}\!{{H}}_{ 6}\to\ ^{ 5}\!{ {I}}_{ 8}$ , $^{ 5}\!{ {G}}_{ 4}{/}^{ 3}\!{ {K}}_{ 7}\to\ ^{ 5}\!{ {I}}_{ 8}$ , $^{ 5}{ {G}}_{ 5}\to$ $^{ 5}\!{ {I}}_{ 8}$ and $^{ 5}\!{ {F}}_{ 3}{/}^{ 5}\!{ {F}}_{ 2}{/}^{ 3}\!{ {K}}_{ 8}\to {}^{ 5}\!{ {I}}_{ 8}$ transitions, respectively. It is also found that the centre wavelength of blue UC emission shifts to 475 nm gradually as Ho^3?+? concentration decreases. Lastly, a brief analysis about UC mechanism is demonstrated according to the experimental results.     

Modeling the Growth Inhibition Kinetics of Baker's Yeast by Potassium Sorbate Using Statistical Approaches

Potassium sorbate is widely used as a preservative in food products. The inhibition kinetics of yeast growth by potassium sorbate was determined in order to predict the inhibition mechanism and develop an antimicrobial activity model. Linear regression resulted in uncompetitive growth inhibition using different concentrations of nutrients in liquid media containing yeast extract, malt extract (YM broth) and potassium sorbate. At 30°C, constant K_s of YM broth to yeast was 0.254%, maximum growth rate (μ_max) of yeast was 0.008 min^-1, and inhibition constant (K_i) of potassium sorbate to yeast growth was 0.324%. This statistical method could reliably determine the growth inhibition mechanism and kinetics.