Pathogenicity of Foodborne, Environmental and Clinical Isolates of Listeria Monocytogenes in Mice

Foodborne, environmental and clinical isolates of Listeria monocytogenes and other Listeria species were screened for pathogenicity in immunocompromised mice. Of 218 isolates of L. monocytogenes, 203 were pathogenic and 15 were nonpathogenic. All non-monocytogenes species were nonpathogenic. Pathogenic isolates were hemolytic for sheep blood. In contrast, many nonpathogenic isolates were weakly hemolytic, but were CAMP positive. Lethal doses (LD₅₀) of pathogenic isolates were 5-480 cells for immunocompromised mice and 7.2 × 10⁵ to 8.4 × 10⁷ for nonimmunocompromised mice; whereas LD₅₀s for nonpathogenic isolates were > 10⁸ cells in both immunocompromised and nonimmunocompromised mice. Selected test isolates of L. monocytogenes were serotyped; the most common serotypes were 1/2b, 1/2a, 3a and 4b. The initial source and serotype of the isolate appeared not to be related to pathogenicity in immunocompromised mice. However, hemolytic activity was related to pathogenicity.     

Reaction of Anatase and Rutile with Barium Carbonate

PTC materials with the nominal composition (Ba_0.997La_0.003) (Ti_1.012Mn0.₀₀₀₅)O_3.025 were prepared from reagent-grade barium carbonate and commercial grades of anatase and rutile. Both forms of TiO₂ had approximately the same crystallite size. The solid state reaction was followed by thermal analysis and by X-ray diffraction and gravimetric measurements during isothermal heat treatments. The reaction kinetics for both mixtures were virtually the same. However, some variations in microstructural development during sintering were observed, which may be related to subtle differences in crystallite character deriving from the different crystal structures of the TiO₂.     

EFFECT OF STIMULUS, BACKGROUND, PERSONALITY, AND SCORING SYSTEM ON THE MANIFESTATION OF HOSTILITY ON THE TAT.

A FIELD-APPROACH INVESTIGATION ON THE DETERMINATION OF TAT HOSTILITY IN STUDENTS INVOLVED THE USE OF SUCH INDEPENDENT VARIABLES AS THE STIMULUS (3 LEVELS OF SCALED PICTORIAL HOSTILITY), BACKGROUND ("IMPERSONAL" OR "LOOK YOUR BEST" INSTRUCTIONS), AND PERSONALITY (PEER AND SELF-CONCEPT EVALUATION AS HOSTILE OR FRIENDLY). 9 SCORING SYSTEMS OF HOSTILITY WERE EXAMINED VIA A TYPE III ANALYSIS OF VARIANCE. THE STIMULUS WAS THE PRIME DETERMINANT. THE SELF-CONCEPT WAS CONSIDERABLY MORE IMPORTANT THAN THE OBJECTIVE POSSESSION OF HOSTILITY. LITTLE DIFFERENCE IN IMPORTANCE WAS FOUND FOR 7 OF THE 9 SCORING SYSTEMS. ALL STIMULUS LEVELS INFLUENCED THE RESPONSE, BUT VARIED WIDELY IN EXTENT OF INFLUENCE ACCORDING TO THE SCORING SYSTEM AND INTERACTION WITH OTHER VARIABLES. (18 REF.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extruded Microchannel-Structured Heat Exchangers

Abstract

In the search for more compact air/liquid heat exchangers, one possibility is to increase the heat transfer coefficient and surface area by a decrease of the size of the fluid channels. A practical example could be seen in the air/water cross-flow heat exchangers used in cars. For such exchangers, minimization of the total volume leads to a very thin structure, with a lot of small and short air channels. We have designed and patented a cross-flow heat transfer surface with microchannels that has such a structure and can be manufactured industrially at a reasonable cost by extrusion either in aluminum or in polymers. The thermo-hydraulic performance of the structure has been simulated using standard correlations and CFD codes, and prototypic structures are under investigation to validate simulations. Compared to classical heat exchangers, our design is superior in flexibility and compactness for air/liquid applications.     

轻便新型核磁共振找水仪及其在堤坝监测中的应用

地面核磁共振(SNMR)找水方法是目前唯一直接找水的地球物理新方法。这种方法原理新颖,经济、快速,为水文地质工作量化提供了新手段。本文简述了该方法的原理、特点,通过实例说明了轻便型找水仪存浅层地下水勘察和堤坝监测等工程地质方面的应用效果。     

基于混合有限元解析法的永磁同步电机永磁体电涡流损耗估计

永磁同步电机永磁体受限于热约束,无法在温度较高的环境下运行,故需减少永磁体上的电涡流损耗,从而降低永磁体上的温度。针对使用有限元法对永磁体电涡流损耗估算时间较长,以及使用解析法估算时难以达到与有限元法相同的精度,采用混合有限元解析法估算永磁体上的电涡流损耗。结合电涡流的反作用,在模拟电机旋转时,无需重复划分三角形区域;使用MATLAB软件仿真模拟,将混合有限元解析法与Galerkin有限元法对比,减少三角形区域划分的个数。由此验证了永磁体上电涡流损耗符合端部效应以及集肤效应的特征,在保证精度的同时,减少了仿真的时间。     

Modified atmosphere packaging of common mushroom

Until recently, the films used for packaging fresh fruits and vegetables were not permeable enough to balance the high respiration rate of mushrooms. Consequently, modified atmosphere packaging (MAP) in sealed pouches or punnets was not appropriate for this commodity. Four microporous films in oriented polypropylene (OPP) and one film currently used to overwrap mushroom punnets (stretchable PVC) were tested. Mushroom punnets placed into pouches were stored at 4 and 10°C for 8 days. the influence of the modified atmosphere on the marketing quality of pre-packed mushrooms was assessed by measuring the external and internal colour, development stage, firmness and microbial growth. A mathematical model was used to predict the gas composition within the pouches at steady state as a function of the film properties and the characteristics of the plant tissues. the equation calculated from the simplified model shows a linear relationship between the reciprocal of O₂ concentration at steady state, (1/x) at 10 and 4°C and the reciprocal of the film permeability, (1/PmO₂).