钻机转盘用大型推力轴承淬火工艺分析及改进

工程钻机及水井钻机转盘用大型推力轴承的加工比较困难,存在淬火变形问题,分析了轴承圈的淬火工艺及淬火变形产生的主要原因,通过设计心用简易淬火压床,改进淬火工艺,减小了轴承圈的变形,提高了制造质量。     

RETRACTED ARTICLE: Quorum-sensing of bacteria and its application

Quorum sensing, or auto induction, as a cell density dependent signaling mechanism in many microorganisms, is triggered via auto inducers which passively diffuse across the bacterial envelope and therefore intracellulaly accumulate only at higher bacterial densities to regulate specialized processes such as genetic competence, bioluminescence, virulence and sporulation. N-acyl homoserine lactones are the most common type of signal molecules. Aquaculture is one of the fastest-growing food-producing industries, but disease outbreaks caused by pathogenic bacteria are a significant constraint on the development of the sector worldwide. Many of these pathogens have been found to be controlled by their quorum sensing systems. As there is relevance between the pathogenic bacteria’s virulence factor expression and their auto inducers, quorum quenching is a new effective anti-infective strategy to control infections caused by bacterial pathogens in aquaculture. The techniques used to do this mainly include the following: (1) the inhibition of signal molecule biosynthesis, (2) blocking signal transduction, and (3) chemical inactivation and biodegradation of signal molecules. To provide a basis for finding alternative means of controlling aquatic diseases by quorum quenching instead of treatment by antibiotics and disinfectants, we will discuss the examination, purification and identification of auto inducers in this paper.     

一株群体感应抑制活性海洋放线菌的筛选与鉴定 *

群体感应抑制剂(Quorum Sensing Inhibitors, QSIs)可以通过干扰群体感应(Quorum Sensing, QS)而有效降低病菌的感染性和毒力, 并且不会胁迫致病菌使其产生耐药性, 是具有前景的抗生素替代品。海洋微生物是新型QSIs的潜在来源。本研究利用紫色杆菌(Chromobacterium violaceum 026, CV026)模型评价QS抑制活性, 在来源于南海中西部和印度洋深海沉积物样品的放线菌中筛选QS抑制活性菌株, 并且根据形态学特征和16S rRNA基因序列鉴定活性菌株。通过筛选获得了菌株SCSIO 53717, 其提取物在CV026模型中能够显著降低指示菌株的紫色菌素产量, 并且在0~1000mg·mL^-1的有效浓度范围内不影响紫色杆菌的生长。菌株SCSIO 53717被鉴定为Kocuria属, 是首次报道的具有QS抑制活性的Kocuria属菌株, 因而具有进一步深入研究的价值。     

荧光熄灭法测定煤矸石中微量锌

在pH8.6的Na2B4O7-HCl缓冲介质中，基于微量Zn^2 对5－溴水杨基荧光酮体系的荧光熄灭效应，建立了测定微量Zn^2 的荧光分析方法。结果表明，当激发波长λex=365nm，荧光发射波长λem=538nm时，Zn^2 量在0.0-400.0μg/L内与体系的荧光熄灭程度呈线性关系，方法的检出限为0.38μg/L。方法用于煤矸石中微量Zn^2 的测定，结果与极谱法结果一致，6次测定的RSD＜3．0％。     

Mean Field Dynamos with Algebraic and Dynamic α-Quenchings

Calculations for mean field dynamo models (in both full spheres and spherical shells), with both algebraic and dynamic -quenchings, show qualitative as well as quantitative differences and similarities in the dynamical behaviour of these models. We summarise and enhance recent results with extra examples. Overall, the effect of using a dynamic appears to be complicated and is affected by the region of parameter space examined.     

Ultraviolet absorbance titration for the determination of conditional stability constants of Hg（Ⅱ） and dissolved organic matter

Strong interaction between natural dissolved organic matter （DOM） and Hg（Ⅱ） may influence the transport, conversion, toxicity and bio-validity of mercury in the environment. In this paper ultraviolet （UV） absorbance titration was employed for the first time for the determination of the conditional stability constants of Hg（Ⅱ） and （DOM）. With increasing Hg（Ⅱ） concentrations, the UV absorbance of fulvic acid, humic acid, and DOM in river increases progressively. By linear and non-linear model fitting, the conditional stability constants （lgK） of Hg（Ⅱ） and DOM were worked out to be 3.54-4.93 and 3.64-4.85, respectively. The results are consistent with those acquired by the typical fluorescence quenching titration method, with the maximum relative error of lgK being 2.6% and the average relative error being 0.2%. The UV absorbance titration method has the advantages of rapid determination, simple performance, and it will probably become a new approach to studying interactions between DOM and trace metallic ions.     

盐藻的室温光抑制

实验用盐藻取自天津塘沽轻工业部制盐研究所,采用ＡＳＰ２培养液为培养基,研究了盐藻的室温光抑制现象,并探讨了盐藻的光保护反应机理,结果表明,盐藻对高辐照有很强的忍耐力,且光合能力的恢复也很强,氯霉素（ＣＡＰ）或二硫苏糖醇（ＤＴＴ）在高光下强烈地加深了对ＰＳＩＩ光化学效率（Ｆｖ／Ｆｍ）和光合量子效率（Φｉ）的抑制,但ＣＡＰ或ＤＴＴ单独作用并不抑制盐藻的光化学系统在低光下的可逆恢复;盐藻在ＣＡＰ＋ＤＴＴ     

液闪法测量断裂带水中3H计数效率的标定

文中介绍了如何使用无氚水作为猝灭剂制备系列猝灭源,建立猝灭校正曲线,从而精确标定Quantulus1220液闪仪测量3H的计数效率。实验结果表明,直线拟合校正曲线计算的效率与测量值的偏差小,计数效率变动范围在21.59%～22.68%之间,系列猝灭源刻度仪器计数效率具有快速可靠等优点     

Quorum-Sensing of Bacteria and Its Application

Quorum sensing, or auto induction, as a cell density dependent signaling mechanism in many microorganisms, is triggered via auto inducers which passively diffuse across the bacterial envelope and therefore intracellulaly accumulate only at higher bacterial densities to regulate specialized processes such as genetic competence, bioluminescence, virulence and sporulation. N-acyl homoserine lactones are the most common type of signal molecules. Aquaculture is one of the fastest-growing food-producing industries, but disease outbreaks caused by pathogenic bacteria are a significant constraint on the development of the sector worldwide. Many of these pathogens have been found to be controlled by their quorum sensing systems. As there is relevance between the pathogenic bacteria's virulence factor expression and their auto inducers, quorum quenching is a new effective anti-infective strategy to control infections caused by bacterial pathogens in aquaculture. The techniques used to do this mainly include the following: (1) the inhibition of signal molecule biosynthesis, (2) blocking signal transduction, and (3) chemical inactivation and biodegradation of signal molecules. To provide a basis for finding alternative means of controlling aquatic diseases by quorum quenching instead of treatment by antibiotics and disinfectants, we will discuss the examination, purification and identification of auto inducers in this paper.     

快速光响应曲线的优化及在底栖甲藻光适应特性研究中的应用

利用快速光响应曲线(RLCs)技术研究了不同光背景下的底栖甲藻Cooliatropicalis的光合作用特性,比较了RLCs的不同序列(正序、反序和非序)和不同光照时间(10, 30和60 s)对光合参数的影响。结果表明:正序RLCs由于序列内非光化学淬灭(NPQ)的快速累积,造成曲线的不饱以及光合参数最大相对电子传递速率(rETRmax)和半饱和光强(Ek)的高估。反序和非序RLCs均出现光饱和或光抑制,步长30s和60s的光合参数在不同光背景下的趋势基本一致。在底栖甲藻的光合生理研究中,可考虑采用步长30 s的反序RLCs进行测定。