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排序方式: 共有311条查询结果,搜索用时 31 毫秒
101.
d-glycero-d-manno-Heptose 1,7-bisphosphate (HBP) plays a unique role in bacteriology. We describe in this study a very efficient synthesis of HBP, featuring a highly 6-D-selective construction of the heptose scaffold as well as a double phosphorylation step installing, in a single operation and in a β-stereoselective manner, the 1- and the 7-phosphates. 相似文献
102.
103.
ZhanboWen Wenhui Yang Na Li Jie wang Lingfei Hu Jinsong Li Zhe Yin Ke Zhang Xiaokai Dong 《Particuology》2014,(2):82-87
To assess the risk of infectious bacterial aerosols leaking to the environment, the filtration efficiency of a biosafety level 3 (BSL-3) laboratory high-efficiency particulate (HEPA) filter was investigated using the aerosolized bacteria Serratia marcescens. The aerosol size was measured using an Andersen sampler. Eight first stage HEPA filters (numbered 1-87 were distributed in contaminated labs and exhausts from each of the first stage HEPA filters were aggregated and filtered through one second stage HEPA filter before being released to the environment. In total, 8 first-stage and I second-stage HEPA filters from the BSL-3 air purification system were analyzed. No S. marcescens was detected in first stage filters 1,2, 4, 5, 7 and 8 and the second stage HEPA filter. The filtration efficiencies against aerosolized S. marcescens were 〉99.9999%. First stage filter numbers 3 and 6 had filtration efficiencies of 99.9825% and 99.9906% respectively. When filter number 3 was replaced by a new filter and the bracket for filter number 6 was sealed, no aerosolized S. marcescens was detected in the filtered air. Our work suggests that the BSL-3 laboratory HEPA filter air purification system is effective against bacterial aerosols, with little to no bacterial leakage into the environment. 相似文献
104.
Gardner JY Brillhart DE Benjamin MM Dixon LG Mitchell LM Dimandja JM 《Journal of separation science》2011,34(2):176-185
The cellular fatty acid profiles of eight strains of Bacillus, Staphylococcus, and Enterobacteriacae (Escherichia coli and Salmonella) were analyzed by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry. A novel template method was developed to standardize the raw two-dimensional gas chromatography retention data through the use of a chemical indexing mixture. Analyte retention coordinates were normalized in the primary dimension with respect to a series of n-alkanes (Kovats index) and in the secondary dimension with respect to a series of aromatic hydrocarbons (Lee index). Fatty acid profiles extracted from the templates were compared by multidimensional scaling and principal component analysis. Differences in the profiles of Gram-positive and Gram-negative bacteria were observed, and a series of heterogeneous mixtures comprising different fractions (containing one Gram-positive and one Gram-negative bacteria strain) were also distinguished from their homogeneous constituents. 相似文献
105.
106.
《Analytical letters》2012,45(16):1291-1302
Abstract The selectivity of a previously reported bacterial arginine electrode has been greatly enhanced, with no loss of response to arginine. The response of this sensor to glutamine and asparagine was found to be due to a contaminant growing in the bacterial layer of the electrode. The addition of 1 × 10?3 M sodium azide to the working buffer and cold storage of the electrode effectively controlled the growth of the contaminating bacteria and maintained the low initial response of the electrode to these amino acids in the concentration range of 4 × 10?5 to 1.5 × 10?3 M. At these optimum conditions, the response of the sensor to arginine was unaffected by the presence of a mixture of amino acids at physiological levels. 相似文献
107.
《Analytical letters》2012,45(13):1111-1124
Abstract A rapid scanning fluorometer is used to obtain fluorescence spectral data characteristic of bacteria which do not readily produce fluorescent pigments. The data is generated in the form of an array of fluorescence intensity as a function of multiple excitation and emission wavelengths. Fluorescence spectral properties are introduced into the bacterial specimen using multiple dye mixtures for staining. The characteristic fluorescent fingerprints are believed to occur by preferential adsorption and reaction of bacterial cellular components with the individual dyes of the mixture. The procedure is found to be rapid and reproducible for the bacteria examined. 相似文献
108.
Highly Stable Bioluminescence-Based Fiber-Optic Sensor Using Immobilized Enzymes from Vibrio Harveyi
《Analytical letters》2012,45(10):2211-2222
Abstract The properties of the bioluminescent enzymatic systems from V. fischeri and V.harveyi immobilized on preactivated polyamide membranes, as well as the characteristics of a fiber-optic biosensor equipped with such membranes, have been studied. Particular attention has been paid to the stability of the bioactive matrices under working conditions, since this remains a key-point for designing operational biosensors of practical use. Whatever the origin of the bioluminescent system, the microdetermination of NADH could be performed at the nanomolar level with detection limits of 2 nM and 0.3 nM with the systems from V. harveyi and V. fischeri, respectively. the use of polyethyleneglycol (PEG 600) improves the operational stability of the bi-enzymatic system from V. fischeri, but a recalibration must be carried out every ten assays. Although the immobilized system from V. harveyi exhibited a lower activity than the enzymes from V. fischeri, its excellent operational stability (100 assays performed within a day without loss in activity) makes it more suitable in designing a truly operational bioluminescence-based NADH sensor. 相似文献
109.
Effects of 3-kJ kg?1 nanosecond pulsed electric fields (PEFs) on cellular permeabilization of Salmonella enterica and Staphylococcus aureus were observed. It was seen that bacterial responses depend on both the electrical pulse attribute and the cell plasma membrane structure. For traditional permeabilization, the responses involved the thickness of the peptidoglycan layer where a maximum of 2.5 log reduction in S. enterica population was achieved. Meanwhile, in the area of selective permeabilization, it showed insignificant reduction in both pathogens. Such inactivation mechanisms were described through the behavior of potential across plasma membrane and intracellular organelles by PSPICE simulations incorporating PEF-cell interaction model. 相似文献
110.
Brandon H. McNaughton Paivo Kinnunen Ron G. Smith Ramon Torres-Isea Roy Clarke 《Journal of magnetism and magnetic materials》2009,321(10):1648-1652
The nonlinear rotation response of a magnetic particle occurs when a driving magnetic field, used to rotate the magnetic particle, exceeds a critical frequency. This type of nonlinear rotational dynamic depends on several physical parameters, such as the rotational drag that the particle experiences. Shifts in this nonlinear rotational frequency offer a dynamic approach for the detection of bacteria, measurement of their growth, their response to chemical agents, and other biomedical applications. Therefore, we have developed a stand-alone prototype device that utilizes an elegant combination of a laser diode and photodiode to monitor particle rotation. 相似文献