Home  About us  Contact
 

Additional Strain (additional + strain)

Distribution by Scientific Domains
Life Sciences33%
Engineering33%

Selected Abstracts

Effective elastic properties of the double-periodically cracked plates

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 15 2005
G. S. Wang
Abstract In this paper, the interaction of double-periodical cracks is accurately solved based on the isolating analysis procedure, superposition principle, pseudo-traction method, Chebyshev polynomial expansion and crack-surface collocation technique. The jump displacement crossing crack faces, the average additional strain and therefore the effective compliance of the double-periodically cracked plate are directly determined. The numerical results for axial-symmetrically distributed double-periodical cracks, general double-periodical cracks with one collinear direction as well as two sets of double-periodical cracks with same size and square distribution are given in this paper. And the partial typical numerical results are compared with the previous works. The analysis shows that the anisotropy induced by the general double-periodical cracks is generally not orthogonal anisotropy. Only when the double-periodical cracks are axial-symmetrically distributed, is the anisotropy orthogonal. In this special cases, the effective engineering constants (consist of effective elastic modulus, the effective Poisson's ratio, the effective shear modulus) of cracked plate versus crack spacing, in the plane stress and plane strain conditions, respectively, are analysed. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Susceptibility of lesser mealworm (Coleoptera: Tenebrionidae) adults and larvae exposed to two commercial insecticides on unpainted plywood panels

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 2 2008
Phillip E Kaufman
Abstract BACKGROUND: The susceptibilities of adult and larval lesser mealworms, Alphitobius diaperinus (Panzer), to two commercially formulated insecticides, cyfluthrin and tetrachlorvinphos, were examined through exposure on treated plywood panels. Lesser mealworms were collected from four caged-layer poultry farms, three in New York and one in Maine. An additional strain was obtained from an infestation occurring in a cricket colony. RESULTS: In all poultry farm derived strains, a portion of the population (1.8,16.2%) survived cyfluthrin exposure. The Maine and cricket colony strains were tolerant of tetrachlorvinphos exposure as both larvae and adults, with 55,74% mortality, whereas nearly 100% mortality was observed with New York strains. The cricket colony adult beetles were highly susceptible to cyfluthrin, with 100% mortality following exposure, but larvae were considerably less susceptible (87.7%). Pesticide use histories for the poultry farms and their impact on the results are discussed. CONCLUSION: The results document that tetrachlorvinphos, an active ingredient with a long use history, may be losing its effectiveness against lesser mealworms in some poultry operations; however, it is still effective in many others. Copyright © 2007 Society of Chemical Industry [source]

On the calculation of crack face opening displacements in fiber reinforced composites under plane loading

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009
Mike Richter
This paper concerns with the calculation of the crack face opening displacement in fiber reinforced composites using analytical, semi-analytical and numerical approaches. Crack bridging is one of the most characteristic effects of fibers on the material behavior of the composite. Knowing the crack face opening displacement the additional strain due to cracks can be calculated and used in homogenization procedures. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Phage-selected lipopolysaccharide mutants of Pectobacterium atrosepticum exhibit different impacts on virulence

JOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2010
T.J. Evans
Abstract Aims:, To positively select Pectobacterium atrosepticum (Pa) mutants with cell surface defects and to assess the impact of these mutations on phytopathogenesis. Methods and Results:, Several phages were isolated from treated sewage effluent and were found to require bacterial lipopolysaccharide (LPS) for infection. Two strains with distinct mutations in LPS were obtained by transposon mutagenesis. Along with a third LPS mutant, these strains were characterized with respect to various virulence-associated phenotypes, including growth rate, motility and exoenzyme production, demonstrating that LPS mutations are pleiotropic. Two of the strains were deficient in the synthesis of the O-antigen portion of LPS, and both were less virulent than the wild type. A waaJ mutant, which has severe defects in LPS biosynthesis, was dramatically impaired in potato tuber rot assays. The infectivity of these novel phages on 32 additional strains of Pa was tested, showing that most Pa isolates were sensitive to the LPS-dependent phages. Conclusions:, Native LPS is crucial for optimal growth, survival and virulence of Pa in vivo, but simultaneously renders such strains susceptible to phage infection. Significance and Impact of the Study:, This work demonstrates the power of phages to select and identify the virulence determinants on the bacterial surface, and as potential biocontrol agents for Pa infections. [source]

Comparison of methods for the detection of methicillin resistance in Staphylococcus aureus isolates from food products

LETTERS IN APPLIED MICROBIOLOGY, Issue 5 2007
M. Corrente
Abstract Aims:, To compare several methods for detection of methicillin resistance in Staphylococcus aureus isolates from food. Methods and Results:, Two hundred S. aureus isolates from food of animal origin were screened for methicillin resistance by a PCR assay specific for the mecA gene, an oxacillin agar screen test and a cefoxitin disk diffusion test. Six out of 200 strains (3%) were found to be methicillin-resistant Staphylococcus aureus (MRSA) by PCR. The oxacillin agar screen test detected only one of the MRSA isolates (sensitivity of 16·7%) and mischaracterized three additional strains as MRSA (specificity of 98·45%). None of the MRSA strains was detected by the cefoxitin test (sensitivity of 0%), while 15 methicillin-susceptible S. aureus (MSSA) strains were misclassified as resistant (specificity of 92·3%). Fifteen MSSA strains displayed a ,-lactamase hyperproducer-like phenotype. The six MRSA (mecA-positive) strains resembled the characteristics of heteroresistant strains. Conclusions:, As MRSA of animal origin may display atypical phenotypes, PCR appears to be more reliable for detection of methicillin resistance in animal strains. Significance and Impact of the Study:, The study stresses the need for implementing the methods of screening S. aureus from food of animal origin for methicillin resistance. [source]

Systemic neonatal candidosis: the karyotyping of Candida albicans strains isolated from neonates and health-workers

MYCOSES, Issue 1 2010
J. Ben Abdeljelil
Summary Candida albicans has become an important cause of nosocomial infections in neonatal intensive care units (NICUs). The aim of the present study was to compare C. albicans strains isolated from neonates (NN) suffering from systemic candidosis and from nurses in order to determine the relatedness between NN and health workers' strains. Thirty-one C. albicans strains were isolated from 18 NN admitted to the NICU of the neonatology service of Farhat Hached Hospital of Sousse, Tunisia and suffering from systemic candidosis, together with five strains recovered from nurses suffering from C. albicans onychomycosis. Two additional strains were tested, one from an adult patient who developed a systemic candidosis and the second from an adult with inguinal intertrigo. All strains were karyotyped by pulsed-field gel electrophoresis (PFGE) with a CHEF-DR II system. Analysis of PFGE patterns yielded by the 38 strains tested led to the identification of three pulsotypes that were designated I, II and III, and consisted of six chromosomal bands with a size ranging from 700 to >2500 kbp. The most widespread was the pulsotype I, which was shared by 17 NN and the five nurses' strains. The identity between NN and nurses' strains is very suggestive of a nosocomial acquisition from health-workers. [source]