Growth of Salmonella enteritidis and Salmonella typhimurium in the presence of quorum sensing signalling compounds produced by spoilage and pathogenic bacteria

The effect of acylated homoserine lactones (AHLs) and autoinducer-2 (AI-2) signalling compounds present in the cell-free culture supernatants (CFS), of Pseudomonas aeruginosa, Yersinia enterocolitica-like GTE 112, Serratia proteamaculans 00612, Y. enterocolitica CITY650 and Y. enterocolitica CITY844, on the growth of two Salmonella Enteritidis and two S. Typhimurium strains was assessed though monitoring of changes in conductance of the medium. Detection times (T_det), area and slope of conductance curves were recorded. Except for P. aeruginosa 108928, which was not found to produce AI-2, all other strains produced both AHLs and AI-2. Thereafter, aliquots (20% in the final volume) of these CFS were transferred into NZ Amine broth inoculated with ca. 10³ CFU/ml of stationary phase cultures of each Salmonella strain. While the CFS of P. aeruginosa induced a shorter detection time, i.e. acceleration of the metabolic activity, the CFS of the other microorganisms increased the detection time of Salmonella strains compared to control samples (i.e. without CFS). Results indicate that the growth of Salmonella may be affected by the presence of Quorum sensing (QS) signalling compounds and/or other novel signals existing in CFS, produced by other bacterial species and confirm the complexity of bacterial communication.     

本征α－Si∶H MIS结构电导机制

利用本征α－Ｓｉ：Ｈ薄膜材料制成了Ａｌ－Ｓｉ（１－ｘ）Ｎｘ－ａ－Ｓｉ：Ｈ金属－绝缘体－半导体结构，用高精度差分电容谱仪在５０℃和暗背景条件下测量了这种结构的变频电容谱及变频电导谱。讨论了该ＭＩＳ结构中可能存在的电导机制，计算了禁带态能谱并根据修正后的实验结果得到了其俘获电子的时间常数及截面。     

全压强范围内同心圆环截面管道的流导计算

本文利用作者在全压强范围内圆形管道的流导计算中提出的理论,对在全压强范围内同心圆环截面管道的流导进行了计算,得到的公式表明,比目前通用经验公式结果更为合理。     

一种电导法测量浮选柱气含率的可行性探究

浮选柱中气含率的大小是参考浮选柱内流态,影响实际分选效果的重要参数之一。以麦克斯维尔模型为原理,提出了用电导法测量气含率,简单方便又不失准确。分别用压差法以及自行设计的电导传感器测量了没有介质的浮选柱在不同表观气速下不同位置的气含率,并进行比较,结果表明,电导法的测量值与压差法极接近,浮选柱气含率的变化趋势也符合规律,是可行的。     

Gamma-radiation-induced grafting of binary mixture of methacrylic acid and 4-vinyl pyridine onto Teflon-FEP film as an effective polar membrane for separation processes

Ionic bifunctional membranes have been synthesized by grafting binary mixture of methacrylic acid (MAAc) and 4-vinyl pyridine (4-VP) onto Teflon-FEP film by pre-irradiation method. Optimum conditions pertaining to maximum percentage of grafting were evaluated as a function of different reaction parameters. Maximum percentage of grafting of binary mixture (MAAc-co-4-VP) (71.29%) was obtained at an optimum total dose of 54.48 kGy and the total concentration was 9.49 mol/L ([4-VP] = 0.07 mol/L and [MAAc ] = 9.42 mol/L) in 5 ml of water. The effect of alcohols as additives to the reaction medium on percent grafting of the binary mixture has also been studied. The membranes were characterized by FTIR spectroscopy, scanning electron microscopy and thermogravimetric analysis. Swelling studies of the membranes were performed in different solvents such as water, benzene, carbon tetrachloride and dimethyl formamide (DMF). Maximum swelling was observed in DMF with minimum swelling in benzene. Metal ion (Cu²⁺, Ni²⁺ and Fe²⁺) uptake studies show better affinity for Fe²⁺ ions. Conductance measurements in different aqueous salt solution showed that these membranes have affinity for Na⁺/K⁺ ions and Cl⁻ ions and hence can be used in desalination/separation processes for the separation of both type of cationic and anionic ions.     

溶胶凝胶法制备ITO透明导电薄膜的工艺研究

以五水硝酸铟和乙酰丙酮为原料,以无水氯化锡为掺杂剂,采用溶胶凝胶工艺,用提拉法在石英玻璃基体上制备了ITO透明导电薄膜.采用DTA-TG、XRD、sEM等测试手段对薄膜从凝胶态向结晶态转变过程及微区形貌特点进行了表征,并利用四探针电阻率仪考察了热处理温度、提拉速度、冷却速度、提拉次数等工艺条件对薄膜的导电性能的影响.结果表明:ITO干凝胶膜在600℃热处理温度下完全转化为结晶态,ITO薄膜具有由球形粒子堆积而成的多孔结构;热处理温度与冷却速度均会对ITO薄膜的导电率产生重要影响.     

Rapid and efficient image restoration technique based on new adaptive anisotropic diffusion function

The anisotropic diffusion is an efficient smoothing process. It is widely used in noise removing and edges preserving via different schemes. In this paper based on a mathematical background and the existing efficient anisotropic function in the literature we developed a new mathematical anisotropic diffusion function which is able to overcome the drawbacks of the traditional process such as the details loss and the image blur. The simulations results and the comparative study with other recent techniques are conducted and showed that the proposed schema generates a wide improvement in the quality of the restored images. This improvement has been shown subjectively in terms of visual quality, and objectively with reference to the computation of some criteria. The simulated images are well de-noised but the most important is that details and structural information are kept intact. In addition to that, the proposed new function was found very interesting and presents numerous advantages like its similarity to the conventional model and the importance of the speed hence it converges faster which allows an opportunity to be well implemented in our de-noising process.     

中子辐照对双极器件电参数的影响

双极型晶体管在受到中子辐照之后,要引起电流增益和饱和压降的退化。本文主要分析:1.不同纵向参数的器件,电流增益在各个区域的退化程度,且与测试h_(FE)时的电流密度及h_(FEo)的关系;2.影响饱和压降变化的各种因素,结果表明电导调制宽度X_c的减小是引起饱和压降退化的主要原因;3.利用加固器件的辐照结果对寿命损伤常数K值进行了推算,由于K是杂质浓度的函数,不同区域K值不同。     

虚拟仪器在电导测定中的应用

采用LabVIEW技术,通过对前面板与框图程序的编程设计,构建了虚拟仪器电导测定系统。系统不仅实现数据采集、处理和分析,而且方便地以图形化方式动态实时显示结果,能够满足实时性要求高的实验及工厂的需要。系统界面友好、操作方便、功能齐全,有着广泛的应用。结合弱电解质的电离平衡常数的测定,就前面板与框图程序的实现具体说明了系统功能。     

A model of friction for a pin-on-disc configuration with imposed pin rotation

A friction model is developed by considering the Coulomb friction model, a probabilistic approach of wear prediction, the kinematics of the pin-on-disc configuration and the elastic theory of bending. The model estimates the magnitude and direction of the frictional force, the pin torque, the probability of asperity contact and the real area of contact distinguishing between the part due to elastic and plastic asperity contacts respectively. Therefore, the proposed model is suitable for the prediction of adhesive wear. It can be applied to metal contacts for conductance characterisation through the plastically deformed asperities which is of great interest for electrical contact resistance studies.