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1
Marri, Laura, Emanuela Barboni, Tiziana Irdani, Brunella Perito, and Giorgio Mastromei. "Restriction enzyme and DNA hybridization analysis of cellulolytic Streptomyces isolates of different origin." Canadian Journal of Microbiology 43, no. 4 (April 1, 1997): 395–99. http://dx.doi.org/10.1139/m97-055.
Повний текст джерелаАнотація:
Streptomyces rochei A2 endoglucanase (eglS) and β-glucosidase (bgs1) genes were used as probes to survey their distribution among 16 Streptomyces strains isolated from different sources and characterized for their cellulolytic activities. The eglS probe hybridized to the genomic DNA of 12 strains with a restriction pattern different from that of S. rochei A2. The DNA from all strains, except one, hybridized with the bgsl probe and one strain showed the same restriction pattern as seen in S. rochei A2. The sequence localized by the eglS probe in S. thermoviolaceus and the one localized by the bgs1 probe in strain EC1 were cloned and expressed in E. coli in plasmids pTAE and pCSF203, respectively. The restriction maps showed that the cloned genes were identical to eglS and bgs1. The restriction enzyme analysis of genomic DNA from all the strains identified nine different groups, each characterized by a distinctive pattern and in agreement with the results of the hybridization experiments.Key words: Streptomyces, cellulase genes, hybridization, restriction enzyme analysis.
2
Lavagnino, Michael, Steven P. Arnoczky, Niell Elvin, and Julie Dodds. "Patellar Tendon Strain is Increased at the Site of the Jumper's Knee Lesion during Knee Flexion and Tendon Loading." American Journal of Sports Medicine 36, no. 11 (September 3, 2008): 2110–18. http://dx.doi.org/10.1177/0363546508322496.
Повний текст джерелаАнотація:
Background Patellar tendinopathy (jumper's knee) is characterized by localized tenderness of the patellar tendon at its origin on the inferior pole of the patella and a characteristic increase in signal intensity on magnetic resonance imaging at this location. However, it is unclear why the lesion typically occurs in this area of the patellar tendon as surface strain gauge studies of the patellar tendon through the range of motion have produced conflicting results. Hypothesis The predicted patellar tendon strains that occur as a result of the tendon loads and patella-patellar tendon angles (PPTAs) experienced during a jump landing will be significantly increased in the area of the patellar tendon associated with patellar tendinopathy. Study Design Descriptive laboratory study. Methods A 2-dimensional, computational, finite element model of the patella-patellar tendon complex was developed using anatomic measurements taken from lateral radiographs of a normal knee. The patella was modeled with plane strain rigid elements, and the patellar tendon was modeled with 8-node plane strain elements with neo-Hookean material properties. A tie constraint was used to join the patellar tendon and patella. Patella-patellar tendon angles corresponding to knee flexion angles between 0° and 60° and patellar tendon strains ranging from 5% to 15% were used as input variables into the computational model. To determine if the location of increased strain predicted by the computational model could produce isolated tendon fascicle damage in that same area, 5 human cadaveric patella-patellar tendon-tibia specimens were loaded under conditions predicted by the model to significantly increase localized tendon strain. Pre- and posttesting ultrasound images of the patella–patellar tendon specimens were obtained to document the location of any injured fascicles. Results Localized tendon strain at the classic location of the jumper's knee lesion was found to increase in association with an increase in the magnitude of applied patellar tendon strain and a decrease in the PPTA. The principal stresses and strains predicted by the model for this localized area were tensile and not compressive in nature. Applying the tendon strain conditions and PPTA predicted by the model to significantly increase localized strain resulted in disruption of tendon fascicles in 3 of the 5 cadaveric specimens at the classic location of the patellar tendinopathy lesion. Conclusion The localized increase in patellar tendon strain that occurs in response to the application of tendon loads and decreased PPTA could induce microdamage at the classic location of the jumper's knee lesion. Clinical Relevance The association of decreasing PPTA with increasing localized tendon strain would implicate the role of knee-joint angle as well as tendon force in the etiopathogenesis of jumper's knee.
3
Fichtelova, V., and K. Kovarcik. "Characterization of two BHV-4 strains isolated in the Czech Republic." Veterinární Medicína 55, No. 3 (April 15, 2010): 106–12. http://dx.doi.org/10.17221/18/2010-vetmed.
Повний текст джерелаАнотація:
This study describes the isolation of bovine herpesvirus 4 (BHV-4) from the respiratory tract of animals suffering from respiratory disease. DNA of new isolates, CH and Ni, was cleaved with <I>Bam</I>HI, <I>Eco</I>RI and <I>Hind</I>III in restriction enzyme analysis and the fragments were identified by co-migration with the restriction profile of the reference strain Movar 33/63 cleaved with the appropriate endonuclease. Typical profiles with polyrepetitive DNA (prDNA) fragments were detected. In order to localize the size variation within the obtained digestion fragments, Southern blot hybridization was performed. Differences between the isolates CH, Ni were localized in both the prDNAs and the unique central part of the genome and were restricted to fragment size variation.
4
Jie, M., C. L. Chow, and X. Wu. "Damage-coupled FLD of Sheet Metals for Warm Forming and Nonproportional Loading." International Journal of Damage Mechanics 20, no. 8 (January 21, 2011): 1243–62. http://dx.doi.org/10.1177/1056789510396331.
Повний текст джерелаАнотація:
A method of forming limit prediction for sheet metals at high temperatures and under nonproportional loading is presented. The method takes into account the strain-softening behaviors of the material at elevated temperatures. A localized necking criterion based on an isotropic damage-coupled acoustic tensor is developed and employed to determine the forming limits of strain-softening materials. The damage evolution equation is developed within the thermo-mechanical framework. A closed-form expression of the forming limit strains is derived by coupling the damage evolution equation into the localized necking criterion. A computer program, incorporating the incremental theory of plasticity, the damage evolution equation and the localized necking criterion, is developed to compute the forming limit strains under several nonproportional loading paths. A series of the uniaxial tensile tests is performed to measure the relevant mechanical properties of AA6061 at the elevated temperature of 450°C. The material damage variables are determined from the measured elastic modulii from a series of loading and unloading paths. The damage evolution equation of AA6061 at 450°C is formulated based on the test data. The computed limit strains are compared with the test results under various loading paths and a good agreement is observed. It is found that the critical damage value is independent on the stress states and loading paths. It may be concluded that the application of the material damage as a reliable criterion of localized necking including the nonproportional loading cases.
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Dorn, C. R., S. M. Scotland, H. R. Smith, G. A. Willshaw, and B. Rowe. "Properties of Vero cytotoxin-producingEscherichia coliof human and animal origin belonging to serotypes other than O157: H7." Epidemiology and Infection 103, no. 1 (August 1989): 83–95. http://dx.doi.org/10.1017/s0950268800030387.
Повний текст джерелаАнотація:
SUMMARYEight non-O157: H7 Vero cytotoxin (VT)-produeingEscherichia coli(VTEC) strains isolated from ill persons and nine bovine and lamb strains of serogroups matching the human strains, were characterized for various properties known to be associated withE. colivirulence. Five different serogroups were represented: O5. O55, O103, O111 and O153. The bovine and lamb strains produced VT1, while 3 human strains produced VT1, 3 produced VT2 and 2 were positive for both VT1 and VT2. The strains were non-haemolytic on horse blood agar, did not produce either heat stable toxin A (STA) or heat labile toxin (LT), and were non-invasive. The CVD419 probe which has been proposed to identify enterohaemorrhagicE. coli(EHEC) hybridized with all of the 05 and 0103 strains, none of the 055 and 0153 strains, and 3 of the 4 0111 strains. The strains carried several different sized plasmids and hybridization of Southern blots with the CVD419 probe identified plasmids ranging in size from 42 × 10 to 90 × 10. The strains did not hybridize with the enteroadherence factor (EAF) probe derived from an enteropathogenic strain and associated with the ability to give localized adherence to HEp-2 cells. Nevertheless five of the strains adhered in a localized pattern to HEp-2 cells and Intestine 407 cells. Adhesion to either HEp-2 or Intestine 407 cells did not correlate with hybridization with the CVD419 probe or haemagglutinating properties.
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Kabrane-Lazizi, Yamina, Mingdong Zhang, Robert H. Purcell, Kirk D. Miller, Richard T. Davey, and Suzanne U. Emerson. "Acute hepatitis caused by a novel strain of hepatitis E virus most closely related to United States strains." Journal of General Virology 82, no. 7 (July 1, 2001): 1687–93. http://dx.doi.org/10.1099/0022-1317-82-7-1687.
Повний текст джерелаАнотація:
A unique hepatitis E virus (HEV) strain was identified as the aetiological agent of acute hepatitis in a United States (US) patient who had recently returned from vacation in Thailand, a country in which HEV is endemic. Sequence comparison showed that this HEV strain was most similar, but not identical, to the swine and human HEV strains recovered in the US. Phylogenetic analysis revealed that this new HEV isolate was closer to genotype 3 strains than to the genotype 1 strains common in Asia. The fact that this HEV was closely related to strains recovered in countries where HEV is not endemic and was highly divergent from Asian HEV strains raises the questions of where the patient’s infection was acquired and of whether strains are geographically as localized as once thought.
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Verma, Anita, and Drusilla L. Burns. "Requirements for Assembly of PtlH with the Pertussis Toxin Transporter Apparatus of Bordetella pertussis." Infection and Immunity 75, no. 5 (March 5, 2007): 2297–306. http://dx.doi.org/10.1128/iai.00008-07.
Повний текст джерелаАнотація:
ABSTRACT PtlH is an essential component of the Ptl system, the type IV transporter responsible for secretion of pertussis toxin (PT) across the outer membrane of Bordetella pertussis. The nine Ptl proteins are believed to interact to form a membrane-spanning apparatus through which the toxin is secreted. In this study, we monitored the subcellular localization of PtlH in strains of B. pertussis lacking PT, lacking other Ptl proteins, or from which ATP has been depleted in order to gain insight into the requirements for assembly of PtlH with the remainder of the Ptl transporter complex that is thought to be tightly embedded in the membrane. We found that PtlH is exclusively localized to the inner membrane fraction of the cell in a wild-type strain of B. pertussis. In contrast, PtlH localized to both the cytoplasmic and inner membrane fractions of a mutant strain of B. pertussis that does not produce PT. In comparison to how it localized in wild-type strains of B. pertussis, PtlH exhibited aberrant localization in strains lacking PtlD, PtlE, PtlF, and PtlG. We also found that localization of PtlH was perturbed in B. pertussis strains that were treated with carbonyl cyanide m-chlorophenylhydrazone and sodium arsenate, which are capable of depleting cellular ATP levels, and in strains of B. pertussis that produce an altered form of PtlH that lacks ATPase activity. When taken together, these results indicate that tight association of PtlH with the membrane, likely through interactions with components of the transporter-PT complex, requires the toxin substrate, a specific subset of the Ptl proteins, and ATP. Based on these data, a model for the assembly of the Ptl transporter-PT complex is presented.
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Rakitin, Andrey L., Yulia K. Yushina, Elena V. Zaiko, Dagmara S. Bataeva, Oksana A. Kuznetsova, Anastasia A. Semenova, Svetlana A. Ermolaeva, et al. "Evaluation of Antibiotic Resistance of Salmonella Serotypes and Whole-Genome Sequencing of Multiresistant Strains Isolated from Food Products in Russia." Antibiotics 11, no. 1 (December 21, 2021): 1. http://dx.doi.org/10.3390/antibiotics11010001.
Повний текст джерелаАнотація:
Food products may be a source of Salmonella, one of the main causal agents of food poisoning, especially after the emergence of strains resistant to antimicrobial preparations. The present work dealt with investigation of the occurrence of resistance to antimicrobial preparations among S. enterica strains isolated from food. The isolates belonged to 11 serovars, among which Infantis (28%), Enteritidis (19%), and Typhimurium (13.4%) predominated. The isolates were most commonly resistant to trimethoprim/sulfamethoxazole (n = 19, 59.38%), cefazolin (n = 15, 46.86%), tetracycline (n = 13, 40.63%), and amikacin (n = 9, 28.13%). Most of the strains (68.75%) exhibited multiple resistance to commonly used antibiotics. High-throughput sequencing was used to analyse three multidrug-resistant strains (resistant to six or more antibiotics). Two of them (SZL 30 and SZL 31) belonged to S. Infantis, while one strain belonged to S. Typhimurium (SZL 38). Analysis of the genomes of the sequenced strains revealed the genes responsible for antibiotic resistance. In the genomes of strains SZL 30 and SZL 31 the genes of antibiotic resistance were shown to be localized mostly in integrons within plasmids, while most of the antibiotic resistance genes of strain SZL 38 were localized in a chromosomal island (17,949 nt). Genomes of the Salmonella strains SZL 30, SZL 31, and SZL 38 were shown to contain full-size pathogenicity islands: SPI-1, SPI-2, SPI-4, SPI-5, SPI-9, SPI-11, SPI-13, SPI-14, and CS54. Moreover, the genome of strain SZL 38 was also found to contain the full-size pathogenicity islands SPI-3, SPI-6, SPI-12, and SPI-16. The emergence of multidrug-resistant strains of various Salmonella serovars indicates that further research on the transmission pathways for these genetic determinants and monitoring of the distribution of these microorganisms are necessary.
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Abishkenov, Maxat, Zhassulan Ashkeyev, Kayrosh Nogaev, Yerbol Bestembek, Kuathan Azimbayev, and Ilgar Tavshanov. "On the possibility of implementing a simple shear in the cross-section of metal materials during caliber rolling." Engineering Solid Mechanics 11, no. 3 (2023): 253–62. http://dx.doi.org/10.5267/j.esm.2023.3.004.
Повний текст джерелаАнотація:
The article analyzes the stress-strain state in the zone of plastic deformation during special caliber rolling. The principle of caliber rolling technology is described, which makes it possible to combine shear and compression deformations in the cross-section of metals, alloys, and metal-matrix composites. The analysis results of stresses and strains during shear rolling in a diamond pass, which included compressive strains that had not been considered in previous studies, revealed that localization or point inversion of stresses and strains is observed in the plastic deformation zone. Stress and strain are localized along the minor and major diagonals of the diamond pass.
10
Soares, Guilherme Corrêa, and Mikko Hokka. "Synchronized Full-Field Strain and Temperature Measurements of Commercially Pure Titanium under Tension at Elevated Temperatures and High Strain Rates." Metals 12, no. 1 (December 23, 2021): 25. http://dx.doi.org/10.3390/met12010025.
Повний текст джерелаАнотація:
Understanding the mechanical behavior of materials at extreme conditions, such as high temperatures, high strain rates, and very large strains, is fundamental for applications where these conditions are possible. Although tensile testing has been used to investigate material behavior under high strain rates and elevated temperatures, it disregards the occurrence of localized strains and increasing temperatures during deformation. The objective of this work is to combine synchronized full-field techniques and an electrical resistive heating system to investigate the thermomechanical behavior of commercially pure titanium under tensile loading at high temperatures and high strain rates. An electrical resistive heating system was used to heat dog-bone samples up to 1120 °C, which were then tested with a tensile Split Hopkinson Pressure Bar at strain rates up to 1600 s−1. These tests were monitored by two high-speed optical cameras and an infrared camera to acquire synchronized full-field strain and temperature data. The displacement and strain noise floor, and the stereo reconstruction error increased with temperature, while the temperature noise floor decreased at elevated temperatures. A substantial decrease in mechanical strength and an increase in ductility were observed with an increase in testing temperature. The localized strains during necking were much higher at elevated temperatures, while adiabatic heating was much lower or non-existent at elevated temperatures.
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Kudva, Indira T., Peter S. Evans, Nicole T. Perna, Timothy J. Barrett, Frederick M. Ausubel, Frederick R. Blattner, and Stephen B. Calderwood. "Strains of Escherichia coli O157:H7 Differ Primarily by Insertions or Deletions, Not Single-Nucleotide Polymorphisms." Journal of Bacteriology 184, no. 7 (April 1, 2002): 1873–79. http://dx.doi.org/10.1128/jb.184.7.1873-1879.2002.
Повний текст джерелаАнотація:
ABSTRACT Escherichia coli O157:H7 (O157) strains demonstrate varied pulsed-field gel electrophoresis patterns following XbaI digestion, which enable epidemiological surveillance of this important human pathogen. The genetic events underlying PFGE differences between strains, however, are not defined. We investigated the mechanisms for strain variation in O157 by recovering and examining nucleotide sequences flanking each of the XbaI restriction enzyme sites in the genome. Our analysis demonstrated that differences between O157 strains were due to discrete insertions or deletions that contained the XbaI sites polymorphic between strains rather than single-nucleotide polymorphisms in the XbaI sites themselves. These insertions and deletions were found to be uniquely localized within the regions of the genome that are specific to O157 compared to E. coli K-12 (O islands), suggesting that strain-to-strain variation occurs in these O islands. These results may be utilized to devise novel strain-typing tools for this pathogen.
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Bressan, José Divo, Luciano Pessanha Moreira, Maria Carolina dos Santos Freitas, Stefania Bruschi, Andrea Ghiotti, and Francesco Michieletto. "Modelling of Forming Limit Strains of AA5083 Aluminium Sheets at Room and High Temperatures." Advanced Materials Research 1135 (January 2016): 202–17. http://dx.doi.org/10.4028/www.scientific.net/amr.1135.202.
Повний текст джерелаАнотація:
Present work analyses mathematical modelling to predict the onset of localized necking and rupture by shear in industrial processes of sheet metal forming of aluminium alloy 5083 such as biaxial stretching and deep drawing. Whereas the AA5083 sheet formability at room temperature is moderate, it increases significantly at high temperature. The Forming Limit Curve, FLC, which is an essential material parameter necessary to numerical simulations by FEM, of AA 5083 sheet was assessed experimentally by tensile and Nakajima testing performed at room and 400°C temperatures. Tensile test specimens at 0o, 45o and 90o to the direction of rolling (RD) and Nakazima type specimens at 0o RD of aluminium AA5083 were fabricated. Simple tensile tests at room and 400°C temperatures were performed to obtain the coefficients of plastic anisotropy and material strain and strain rate hardening behavior at different temperatures. Nakazima biaxial tests at room and high temperature, employing spherical punch were carried out to plot the limit strains in the negative and positive quadrant of the Map of Principal Surface Limit Strains, MPLS, of aluminium AA5083 sheet. The “Forming Map of Principal Surface Limit Strains”, MPLS, shows the experimental FLC which is the plot of principal true strains in the sheet metal surface (ε1,ε2), occurring at critical points obtained in laboratory formability tests or in the fabrication process of parts. Two types of undesirable rupture mechanisms can occur in sheet metal forming products: localized necking and rupture by induced shear stress. Therefore, two kinds of limit strain curves can be plotted in the forming map: the local necking limit curve FLC-N and the shear stress rupture limit curve FLC-S. Localized necking is theoretically anticipated to occur by two mathematical models: Marciniak-Kuczynski modelling, hereafter M-K approach, and D-Bressan modeling. Prediction of limit strains are presented and compared with the experimental FLC. The shear stress rupture criterion modeling by Bressan and Williams and M-K models are employed to predict the forming limit strain curves of AA5083 aluminium sheet at room and 400°C temperatures. As a result of analysis, a new concept of ductile rupture by shear stress and local necking are proposed. M-K model has good agreement with both D-Bressan models.
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Chow, C. L., M. Jie, and S. J. Hu. "Forming Limit Analysis of Sheet Metals Based on a Generalized Deformation Theory." Journal of Engineering Materials and Technology 125, no. 3 (July 1, 2003): 260–65. http://dx.doi.org/10.1115/1.1586938.
Повний текст джерелаАнотація:
This paper presents the development of a generalized method to predict forming limits of sheet metals. The vertex theory, which was developed by Sto¨ren and Rice (1975) and recently simplified by Zhu, Weinmann and Chandra (2001), is employed in the analysis to characterize the localized necking (or localized bifurcation) mechanism in elastoplastic materials. The plastic anisotropy of materials is considered. A generalized deformation theory of plasticity is proposed. The theory considers Hosford’s high-order yield criterion (1979), Hill’s quadratic yield criterion and the von Mises yield criterion. For the von Mises yield criterion, the generalized deformation theory reduces to the conventional deformation theory of plasticity, i.e., the J2-theory. Under proportional loading condition, the direction of localized band is known to vary with the loading path at the negative strain ratio region or the left hand side (LHS) of forming limit diagrams (FLDs). On the other hand, the localized band is assumed to be always perpendicular to the major strain at the positive strain ratio region or the right hand side (RHS) of FLDs. Analytical expressions for critical tangential modulus are derived for both LHS and RHS of FLDs. For a given strain hardening rule, the limit strains can be calculated and consequently the FLD is determined. Especially, when assuming power-law strain hardening, the limit strains can be explicitly given on both sides of FLD. Whatever form of a yield criterion is adopted, the LHS of the FLD always coincides with that given by Hill’s zero-extension criterion. However, at the RHS of FLD, the forming limit depends largely on the order of a chosen yield function. Typically, a higher order yield function leads to a lower limit strain. The theoretical result of this study is compared with those reported by earlier researchers for Al 2028 and Al 6111-T4 (Grafand Hosford, 1993; Chow et al., 1997).
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Prasad, K. Sajun, Sushanta Kumar Panda, Sujoy Kumar Kar, S. V. S. Narayana Murty, and S. C. Sharma. "Effect of Bending Strain in Forming Limit Strain and Stress of IN-718 Sheet Metal." Materials Science Forum 830-831 (September 2015): 238–41. http://dx.doi.org/10.4028/www.scientific.net/msf.830-831.238.
Повний текст джерелаАнотація:
The forming limit diagram (ε-FLD) was estimated by deforming IN-718 sheet metal in different strain paths using a sub-size limiting dome height test set-up. The bending strains induced due to the use of smaller punch were estimated in all the strain paths, and the corrected ε-FLD was evaluated. The mathematical models such as Hill localized necking, Swift diffuse necking and Storen-Rice bifurcation theories were implemented to predict the limiting strains. In-order to avoid the path dependency of the ε-FLD during multi-stage forming process, stress based forming limit diagram (σ-FLD) was estimated using von-Mises and Hill-48 anisotropy plasticity theory with incorporation of Hollomon power hardening law. It was found that the bending strain influenced the limiting strains and stresses in the forming limit diagram. However, IN-718 material has encouraging formability in stretch forming process. The plot of the equivalent strains versus triaxiality indicated increasing limiting strain of the material in tension-tension mode.
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Campbell, C. L., and P. E. Thorsness. "Escape of mitochondrial DNA to the nucleus in yme1 yeast is mediated by vacuolar-dependent turnover of abnormal mitochondrial compartments." Journal of Cell Science 111, no. 16 (August 15, 1998): 2455–64. http://dx.doi.org/10.1242/jcs.111.16.2455.
Повний текст джерелаАнотація:
Inactivation of Yme1p, a mitochondrially-localized ATP-dependent metallo-protease in the yeast Saccharomyces cerevisiae, causes a high rate of DNA escape from mitochondria to the nucleus as well as pleiotropic functional and morphological mitochondrial defects. The evidence presented here suggests that the abnormal mitochondria of a yme1 strain are degraded by the vacuole. First, electron microscopy of Yme1p-deficient strains revealed mitochondria physically associated with the vacuole via electron dense structures. Second, disruption of vacuolar function affected the frequency of mitochondrial DNA escape from yme1 and wild-type strains. Both PEP4 or PRC1 gene disruptions resulted in a lower frequency of mitochondrial DNA escape. Third, an in vivo assay that monitors vacuole-dependent turnover of the mitochondrial compartment demonstrated an increased rate of mitochondrial turnover in yme1 yeast when compared to the rate found in wild-type yeast. In this assay, vacuolar alkaline phosphatase, encoded by PHO8, was targeted to mitochondria in a strain bearing disruption to the genomic PHO8 locus. Maturation of the mitochondrially localized alkaline phosphatase pro-enzyme requires proteinase A, which is localized in the vacuole. Therefore, alkaline phosphatase activity reflects vacuole-dependent turnover of mitochondria. This assay reveals that mitochondria of a yme1 strain are taken up by the vacuole more frequently than mitochondria of an isogenic wild-type strain when these yeast are cultured in medium necessitating respiratory growth. Degradation of abnormal mitochondria is one pathway by which mitochondrial DNA escapes and migrates to the nucleus.
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Lin, I. C., M. H. Lee, P. C. Wu, S. C. Lin, J. W. Chen, C.-C. Li, G. Y. Guo, Y.-H. Chu, R. Sankar, and M.-W. Chu. "Atomic-scale observation of spontaneous hole doping and concomitant lattice instabilities in strained nickelate films." New Journal of Physics 24, no. 2 (February 1, 2022): 023011. http://dx.doi.org/10.1088/1367-2630/ac4b10.
Повний текст джерелаАнотація:
Abstract Thin oxide films are of vast opportunities for modern electronics and can facilitate emergent phenomena by factors absent in the bulk counterparts, such as the ubiquitous epitaxial strain and interfacial charge doping. Here, we demonstrate the twisting of intended bulk-metallic phases in 10-unit-cell LaNiO3, PrNiO3, and NdNiO3 films on (001)-oriented SrTiO3 into distinct charge-lattice entangled states by epitaxial strains. Using atomically-resolved electron microscopy and spectroscopy, the interfacial electron doping into SrTiO3 in the conventional context of band alignments are discounted. Instead, spontaneously doped holes that are localized and at the order of 1013 cm−2 are atomically unraveled across all three heterointerfaces and associated with strain mitigations by the accompanied atomic intermixing with various ionic radii. The epitaxial strains also lead to condensations of monoclinic-C2/c lattice instabilities, which are hidden to the bulk phase diagram. The group-theoretical analysis of characteristic transition pathways unveils the strain resurrection of the hidden C2/c symmetry. While this strain-induced monoclinic phase in LaNiO3 remains metallic at room temperature, those in PrNiO3 and NdNiO3 turn out to be insulating. Such strain-induced monoclinic lattice instabilities and parasitic localized holes go beyond the classical elastic deformations of films upon epitaxial strains and hint on plausible hidden orders in versatile oxide heterostructures with unexpected properties, of which the exploration is only at the infancy and full of potentials.
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Nissinen, R., F. M. Lai, M. J. Laine, P. J. Bauer, A. A. Reilley, X. Li, S. H. De Boer, C. A. Ishimaru, and M. C. Metzler. "Clavibacter michiganensis subsp. Sepedonicus Elicits a Hypersensitive Response in Tobacco and Secretes Hypersensitive Response-Inducing Protein(s)." Phytopathology® 87, no. 7 (July 1997): 678–84. http://dx.doi.org/10.1094/phyto.1997.87.7.678.
Повний текст джерелаАнотація:
Strains of Clavibacter michiganensis subsp. sepedonicus, causal agent of bacterial ring rot of potato, showed marked differences in virulence on host plants. When infiltrated into tobacco leaves, virulent strains caused a rapid localized necrotic response (within 24 to 48 h) characteristic of the hypersensitive response (HR), whereas nonpathogenic strains did not. Concentrated cell-free culture supernatants (CCS) from virulent strains caused a necrotic reaction on tobacco, whereas CCS from nonpathogenic strains did not. The necrosis-inducing activity was heat stable and protease sensitive. Inhibitors of eukaryotic metabolism suppressed the necrotic reaction of tobacco to CCS. No necrotic response was observed when host plants were infiltrated with either cells or CCS from virulent strains. HR-inducing protein(s) from a virulent strain separated from the majority of other proteins on DEAE cellulose at 250 to 300 mM NaCl. Ammonium sulfate-precipitated proteins from a virulent strain produced a necrotic reaction at a total protein concentration of 18 μg/ml, whereas those from a nonpathogenic strain did not, even at a concentration of 180 μg/ml. We conclude that virulent strains of C. michiganensis subsp. sepedonicus elicit a typical HR in tobacco and secrete proteinaceous elicitor(s) of the nonhost HR.
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Avsaroglu, H., A. S. van der Sar, H. A. van Lith, L. F. M. van Zutphen, and L. J. Hellebrekers. "Differences in response to anaesthetics and analgesics between inbred rat strains." Laboratory Animals 41, no. 3 (July 1, 2007): 337–44. http://dx.doi.org/10.1258/002367707781282811.
Повний текст джерелаАнотація:
Differences in response to analgesic and anaesthetic drugs can partly be attributed to variations in the genetic background of experimental animals. This study was carried out to determine differences in the response of inbred rat strains to a selection of analgesics and drugs used in anaesthetic protocols. A cross between the most contrasting strains can then be phenotyped in future studies in order to localize quantitative trait loci (QTLs) involved in analgesic/anaesthetic drug sensitivity. Eight inbred strains ( n = 6 rats/strain) were selected for the study: the pigmented ACI, BN and COP strains and the albino F344, LEW, SHR, WAG and WKY strains. Each rat was injected intravenously with two analgesics (buprenorphine 0.05 mg/kg and nalbuphine 1 mg/kg) and three drugs used in anaesthetic protocols (propofol 25 mg/kg, medetomidine 50 μg/kg and ketamine 10 mg/kg), respectively, using a crossover design. Analgesic responses were assessed using an analgesiometric procedure. The sleep time of the rat and, where applicable, the interval between injection and loss of righting reflex were used to determine the anaesthetic response. Six out of eight strains responded significantly different from each other to the analgesic effect of buprenorphine with the ACI strain as hyper-responder. The tail withdrawal latency at 55°C of the F344 and WKY rats using buprenorphine was not significantly different from baseline tail withdrawal latencies. In this study, all strains were non-responsive to the analgesic effects of nalbuphine. The response to all three drugs used in anaesthetic protocols differed significantly among the strains. The F344 and BN strains were relatively resistant to the sedative effects of medetomidine. Use of ketamine was abandoned in the ACI and BN strains when the first two animals of both strains died soon after induction. With all three drugs the sleep time of albino rats was significantly longer compared with that of the pigmented ones. We conclude that the results from this study can be used in future studies where QTLs for the sensitivity to anaesthetic/analgesic drugs are localized.
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Bilal, Mahmood Y. "Similarity Index–Probabilistic Confidence Estimation of SARS-CoV-2 Strain Relatedness in Localized Outbreaks." Epidemiologia 3, no. 2 (May 6, 2022): 238–49. http://dx.doi.org/10.3390/epidemiologia3020019.
Повний текст джерелаАнотація:
Outbreaks of SARS-CoV-2 can be attributed to expanding small-scale localized infection subclusters that eventually propagate into regional and global outspread. These infections are driven by spatial as well as temporal mutational dynamics wherein virions diverge genetically as transmission occurs. Mutational similarity or dissimilarity of viral strains, stemming from shared spatiotemporal fields, thence serves as a gauge of relatedness. In our clinical laboratory, molecular epidemiological analyses of strain association are performed qualitatively from genomic sequencing data. These methods however carry a degree of uncertainty when the samples are not qualitatively, with reasonable confidence, deemed identical or dissimilar. We propose a theoretical mathematical model for probability derivation of outbreak-sample similarity as a function of spatial dynamics, shared and different mutations, and total number of samples involved. This Similarity Index utilizes an Essen-Möller ratio of similar and dissimilar mutations between the strains in question. The indices are compared to each strain within an outbreak, and then the final Similarity Index of the outbreak group is calculated to determine quantitative confidence of group relatedness. We anticipate that this model will be useful in evaluating strain associations in SARS-CoV-2 and other viral outbreaks utilizing molecular data.
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Guth, Beatriz E. C., Regina Giraldi, Tania A. T. Gomes, and Lilian R. M. Marques. "Survey of cytotoxin production among Escherichia coli strains characterized as enteropathogenic (EPEC) by serotyping and presence of EPEC adherence factor (EAF) sequences." Canadian Journal of Microbiology 40, no. 5 (May 1, 1994): 341–44. http://dx.doi.org/10.1139/m94-056.
Повний текст джерелаАнотація:
A total of 108 Escherichia coli strains characterized as enteropathogenic (EPEC) by serotyping and the presence of EPEC adherence factor (EAF) sequences were examined for cytotoxin production by cell line assays and colony hybridization with Shiga-like toxin (SLT) probes. Cytolethal distending toxin (CLDT) production was found in three (2.8%) strains belonging to serotype 086:H34, while one O11 lab:NM strain hybridized with a SLT-II probe but did not express any cytotoxic activity. All four strains showed localized adherence to HeLa cells and hybridized to an E. coli attaching–effacing gene (eae) probe. The CLDT-producing strains had multiple plasmids and some were present in all strains, including a plasmid of ~54 MDa that hybridized with the EAF probe.Key words: enteropathogenic Escherichia coli, EPEC adherence factor sequences, Shiga-like toxin, cytolethal distending toxin.
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Hohenberger, Travis W., Richard J. Windslow, Nicola M. Pugno, and James J. C. Busfield. "A CONSTITUTIVE MODEL FOR BOTH LOW AND HIGH STRAIN NONLINEARITIES IN HIGHLY FILLED ELASTOMERS AND IMPLEMENTATION WITH USER-DEFINED MATERIAL SUBROUTINES IN ABAQUS." Rubber Chemistry and Technology 92, no. 4 (October 1, 2019): 653–86. http://dx.doi.org/10.5254/rct.19.80387.
Повний текст джерелаАнотація:
ABSTRACT Strain energy functions (SEFs) are used to model the hyperelastic behavior of rubberlike materials. In tension, the stress–strain response of these materials often exhibits three characteristics: (i) a decreasing modulus at low strains (<20%), (ii) a constant modulus at intermediate strains, and (iii) an increasing modulus at high strains (>200%). Fitting an SEF that works in each regime is challenging when multiple or nonhomogeneous deformation modes are considered. The difficulty increases with highly filled elastomers because the small strain nonlinearity increases and finite-extensibility occurs at lower strains. One can compromise by fitting an SEF to a limited range of strain, but this is not always appropriate. For example, rubber seals in oilfield packers can exhibit low global strains but high localized strains. The Davies–De–Thomas (DDT) SEF is a good candidate for modeling such materials. Additional improvements will be shown by combining concepts from the DDT and Yeoh SEFs to construct a more versatile SEF. The SEF is implemented with user-defined material subroutines in Abaqus/Standard (UHYPER) and Abaqus/Explicit (VUMAT) for a three-dimensional general strain problem, and an approach to overcome a mathematically indeterminate stress condition in the unstrained state is derived. The complete UHYPER and VUMAT subroutines are also presented.
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Podolin, P. L., P. Denny, C. J. Lord, N. J. Hill, J. A. Todd, L. B. Peterson, L. S. Wicker, and P. A. Lyons. "Congenic mapping of the insulin-dependent diabetes (Idd) gene, Idd10, localizes two genes mediating the Idd10 effect and eliminates the candidate Fcgr1." Journal of Immunology 159, no. 4 (August 15, 1997): 1835–43. http://dx.doi.org/10.4049/jimmunol.159.4.1835.
Повний текст джерелаАнотація:
Abstract The development of autoimmune diabetes in the nonobese diabetic (NOD) mouse is under the control of multiple insulin-dependent diabetes (Idd) genes. The Idd3 gene, originally defined as a broad peak of linkage on mouse chromosome 3, was subsequently identified as two genes, Idd3 and Idd10, separated by at least 20 cM. The resistance alleles of Idd3 and Idd10 individually confer only partial protection from diabetes but, in combination, result in profound resistance to disease due to an epistatic genetic interaction. In this study, we used newly developed congenic strains to further localize Idd10. Surprisingly, we found that Idd10 itself comprises at least two linked loci: Idd10 and the newly designated Idd17. Idd17 was localized to a 1.1-cM region between D3Mit26 and D3Mit40, proximal to Fcgr1, a candidate gene encoding the high affinity Fc receptor for IgG. Idd10 was localized to a 10-cM region between D3Mit213 and D3Mit106, distal to Fcgr1. Thus, Fcgr1 was excluded as a candidate for either Idd10 or Idd17, despite the fact that the NOD strain expresses a mutant form of the receptor. Interestingly, although Idd10 and Idd17 participate in a genetic interaction with each other, Idd10 but not Idd17 participates in the genetic interaction with Idd3. Our study on chromosome 3 begins to reveal the extent of the polygenic nature of autoimmune diabetes, and demonstrates that the use of congenic strains is an effective mapping strategy, even in the dissection of multiple, linked genes with subtle effects.
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Beutin, Lothar, Olivier Marchés, Karl A. Bettelheim, Kerstin Gleier, Sonja Zimmermann, Herbert Schmidt, and Eric Oswald. "HEp-2 Cell Adherence, Actin Aggregation, and Intimin Types of Attaching and Effacing Escherichia coli Strains Isolated from Healthy Infants in Germany and Australia." Infection and Immunity 71, no. 7 (July 2003): 3995–4002. http://dx.doi.org/10.1128/iai.71.7.3995-4002.2003.
Повний текст джерелаАнотація:
ABSTRACT Fecal samples from healthy children under 2 years of age living in Berlin, Germany (205 infants), and Melbourne, Australia (184 infants), were investigated for the presence of attaching and effacing (AE) Escherichia coli (AEEC) strains by screening for eae (intimin) genes. Twenty-seven AEEC strains were isolated from 14 children (7.6%) from Melbourne and from 12 children (5.9%) from Berlin. The 27 AEEC strains were classified as enterohemorrhagic E. coli (one strain, producing Shiga toxin 1), typical enteropathogenic E. coli (EPEC) (one strain carrying an EPEC adherence factor [EAF] plasmid), and atypical EPEC (25 strains negative for Shiga toxins and EAF plasmids). The AEEC were divided into 18 different serotypes, O-nontypeable and O-rough strains. Typing of their intimin genes revealed the presence of intimin α in 6 strains, intimin β in 11 strains, intimin γ in 7 strains, intimin ζ in 2 strains, and intimin η in one strain. Analysis of HEp-2 cell adherence showed diffuse adherence or localized adherence-like patterns in 26 AEEC strains; local adherence was found only with the EAF-positive strain. Ten AEEC strains showed an AE property with the fluorescent actin staining (FAS) test. The introduction of an EAF plasmid (pMAR7) converted 11 FAS-negative AEEC strains to FAS positive and increased the FAS reaction in six FAS-positive AEEC strains, indicating that the genes needed for the AE phenotype were functional in these strains. Our finding indicates that atypical EPEC strains could play a double role as strains that naturally immunize against intimin in humans and as reservoirs for new emerging human pathogenic EPEC strains.
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Milisavljevic, Mira, Drazen Papic, Gordana Timotijevic, and Vesna Maksimovic. "Successful production of recombinant buckwheat cysteine-rich aspartic protease in Escherichia coli." Journal of the Serbian Chemical Society 74, no. 6 (2009): 607–18. http://dx.doi.org/10.2298/jsc0906607m.
Повний текст джерелаАнотація:
Herein, the expression of recombinant cysteine-rich atypical buckwheat (Fagopyrum esculentum) aspartic protease (FeAPL1) in five Escherichia coli strains differing in their expression capabilities is presented. It was shown that the expression success depended highly on the choice of FeAPL1 fusion partner. His6-FeAPL1 was produced in large quantities as an insoluble protein localized in inclusion bodies. On the other hand, MBP-FeAPL1 was localized in both the cytoplasm and inclusion bodies in BL21 and Rosetta-gami strains. Only purified soluble MBP-FeAPL1 from Rosetta-gami cells showed proteolytic activity at pH 3.0 with BSA as the substrate. The results also indicated that FeAPL1 contained a PRO segment that had to be removed for the enzyme activity to appear. The activity of FeAPL1 produced in the Rosetta-gami strain, which enables disulfide bond formation, indicated the importance of the twelve cysteine residues for correct folding and functionality.
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Grozdanov, Lubomir, Carsten Raasch, Jürgen Schulze, Ulrich Sonnenborn, Gerhard Gottschalk, Jörg Hacker, and Ulrich Dobrindt. "Analysis of the Genome Structure of the Nonpathogenic Probiotic Escherichia coli Strain Nissle 1917." Journal of Bacteriology 186, no. 16 (August 15, 2004): 5432–41. http://dx.doi.org/10.1128/jb.186.16.5432-5441.2004.
Повний текст джерелаАнотація:
ABSTRACT Nonpathogenic Escherichia coli strain Nissle 1917 (O6:K5:H1) is used as a probiotic agent in medicine, mainly for the treatment of various gastroenterological diseases. To gain insight on the genetic level into its properties of colonization and commensalism, this strain's genome structure has been analyzed by three approaches: (i) sequence context screening of tRNA genes as a potential indication of chromosomal integration of horizontally acquired DNA, (ii) sequence analysis of 280 kb of genomic islands (GEIs) coding for important fitness factors, and (iii) comparison of Nissle 1917 genome content with that of other E. coli strains by DNA-DNA hybridization. PCR-based screening of 324 nonpathogenic and pathogenic E. coli isolates of different origins revealed that some chromosomal regions are frequently detectable in nonpathogenic E. coli and also among extraintestinal and intestinal pathogenic strains. Many known fitness factor determinants of strain Nissle 1917 are localized on four GEIs which have been partially sequenced and analyzed. Comparison of these data with the available knowledge of the genome structure of E. coli K-12 strain MG1655 and of uropathogenic E. coli O6 strains CFT073 and 536 revealed structural similarities on the genomic level, especially between the E. coli O6 strains. The lack of defined virulence factors (i.e., alpha-hemolysin, P-fimbrial adhesins, and the semirough lipopolysaccharide phenotype) combined with the expression of fitness factors such as microcins, different iron uptake systems, adhesins, and proteases, which may support its survival and successful colonization of the human gut, most likely contributes to the probiotic character of E. coli strain Nissle 1917.
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Nicolas, Andrea, Alberto W. Mello, and Michael D. Sangid. "The Effect of Strain Localization on Galvanic Corrosion Pitting in AA7050." Corrosion 74, no. 8 (March 20, 2018): 860–72. http://dx.doi.org/10.5006/2729.
Повний текст джерелаАнотація:
Corrosion is the primary failure mechanism for sea-based structures, as it plays an important role in material degradation and structural integrity. The localized corrosion behavior is affected by the micromechanics and the electrochemistry of the material; however, there are very limited studies where both mechanisms are studied jointly, let alone relative to microstructural attributes, i.e., at the mesoscale. High-resolution strain maps are created on pre-loaded AA7050 in the transverse-short orientation via digital image correlation to identify strain accumulation with respect to the microstructure. Afterward, this material is subjected to a galvanic corrosion environment. In order to investigate the driving force for localized corrosion, the microstructure, the cathodic particles, the localized strain, and the evolution of surface topology caused by corrosion pitting are spatially characterized in the region of interest. The evolution of the corroded surface is tracked every 24 h throughout the 20 d of corrosion that the material was immersed in 0.6 M NaCl solution. Specifically, three representative sized cathodic particles are monitored throughout the corrosion study, to identify their evolution of pitting before and after the particles fallout from contact with the matrix. Finally, the relationship between strain and localized galvanic corrosion is quantitatively investigated using Gaussian process modeling to identify the underlying correlations. The results show that localized strains within ±3σ of the macroscopic residual strain do not affect the corrosion rate of the material; however, extreme values beyond that threshold associated with the cracking of the particle itself seem to heavily promote the growth of localized galvanic corrosion.
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Zhu, Xinhai, Klaus Weinmann, and Abhijit Chandra. "A Unified Bifurcation Analysis of Sheet Metal Forming Limits." Journal of Engineering Materials and Technology 123, no. 3 (February 7, 2001): 329–33. http://dx.doi.org/10.1115/1.1370397.
Повний текст джерелаАнотація:
The purpose of this study is to determine analytically the orientations of localized necks occurring in sheet metal forming processes, and obtain the corresponding forming limit diagrams (FLDs). In addition to the force equilibrium condition as adopted by other researchers, we include the moment equilibrium in this study. The shear terms due to the perturbation are found to vanish inside the localized neck of a region of deformation. This simplifies the two-dimensional problem to a one-dimensional problem. Furthermore, it is found that there are only three possible orientations for the initiation of a localized neck, i.e., two principal directions and one zero extension direction (which applies only to negative strain ratio deformations). A special case study using the von Mises yield criterion is also presented in this paper. Predictions from our unified analysis matches with the results of Hill, R., 1952, “On Discontinuous Plastic States, With Special Reference to Localized Necking in Thin Sheets,” J. Mech. Phys. Solids, 1, pp. 19–30. For the negative strain ratio regime (left-hand side of the FLDs), and with the results of Storen, S., and Rice, R., 1975, “Localized Necking in Thin Sheets,” J. Mech. Phys. Solids, 23, pp. 421–441. For the positive strain ratio regime (right hand-side of the FLD). When the localized neck is assumed to be in the zero extension direction for the negative strain ratio deformation, deformation theory and flow theory of plasticity give the same limit strains, and a unified solution to the limit strain is obtained. This solution is independent of the specific yield criterion used.
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Leicht, Lena, Franz Bracklow, Marcus Hering, and Manfred Curbach. "Behaviour of reinforcement in drop tower beam tests." MATEC Web of Conferences 323 (2020): 01007. http://dx.doi.org/10.1051/matecconf/202032301007.
Повний текст джерелаАнотація:
Drop tower tests help to gain understanding about the general behaviour of reinforced concrete members under impact loading and to analyse strains and strain rates occurring within their reinforcement. For this purpose, beam and slab specimens are usually employed. The main advantage of beams compared to slabs is that they are less complex due to the almost two-dimensional instead of three-dimensional wave propagation within them. To investigate the steel strains and strain rates, ten impact tests on beam specimens with various impact energies were performed. The impactor sizes and velocities were varied. The reinforcement bars of the beams were instrumented with semiconductor strain gauges. The measured data suggest that the occurring strains in beam tests are independent of the loading velocity. The same was found for the strain rates. The reason is that higher impact energies mostly influence the concrete damage due to spalling on the impact-facing side which happens after the maximum strains occurred. The strains in the reinforcement bars generally result from the overall deflection because of the impact, the spreading of longitudinal waves in the horizontal direction, and the localized cracking of the concrete due to the formation of a punching cone.
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Scaletsky, Isabel C. A., Margareth Z. Pedroso, Carlos A. G. Oliva, Rozane L. B. Carvalho, Mauro B. Morais, and Ulysses Fagundes-Neto. "A Localized Adherence-Like Pattern as a Second Pattern of Adherence of Classic Enteropathogenic Escherichia coli to HEp-2 Cells That Is Associated with Infantile Diarrhea." Infection and Immunity 67, no. 7 (July 1, 1999): 3410–15. http://dx.doi.org/10.1128/iai.67.7.3410-3415.1999.
Повний текст джерелаАнотація:
ABSTRACT Escherichia coli strains that cause nonbloody diarrhea in infants are known to present three distinct patterns of adherence to epithelial cells, namely, localized (LA), diffuse (DA), and aggregative (AA) adherence. Strains with LA (typical EnteropathogenicEscherichia coli [EPEC]) are well recognized as a cause of secretory diarrhea, but the role of strains with DA (DAEC) is controversial, and strains with AA (EAEC) have been more frequently related to persistent diarrhea whereas its relationship with acute diarrhea is not well defined. To determine the relationship of the different types of E. coli adherence patterns with acute diarrhea (lasting less than 14 days) and persistent diarrhea (lasting more than 14 days) in São Paulo, Brazil, we studied stool specimens from 40 infants under 1 year of age with diarrhea and 40 age-matched control infants without any gastrointestinal symptoms. Twenty-eight (35.0%) of eighty cases yielded adherent E. coli (HEp-2 cells). Strains with localized and aggregative adherence were associated with acute and persistent diarrhea. A total of 11.2% of the adherent strains were typical EPEC serotypes and hybridized with the enteroadherence factor probe; 5.0% were EAEC and hybridized with the EAEC probe. DAEC strains were isolated from 10.0% of patients and 7.5% of controls and did not hybridize with the two probes used (daaC and AIDA-I). Strains with a localized adherence-like pattern (atypical EPEC) were found significantly more frequently (P = 0.028) in cultures from children with diarrhea (17.5%) than in controls (2.5%).
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Wang, Jian, Junhui Huang, Yuanhe Li, Kun Ding, Desheng Jiang, Xiuming Dou, and Baoquan Sun. "Strain-induced exciton localized states in quantum well." Applied Physics Letters 122, no. 1 (January 2, 2023): 012104. http://dx.doi.org/10.1063/5.0130104.
Повний текст джерелаАнотація:
We use AlAs sacrificial layer etching technology to peel a film of In0.15Ga0.85As/GaAs single quantum wells (QWs) from a GaAs substrate and transfer the film to a Si wafer covered with randomly distributed Au nanoparticles. In this way, local strains are introduced into the QW film, which leads to the formation of the exciton confinement potential. From them, we have observed very sharp emission lines in photoluminescence (PL) spectra and local PL bright spots in space. The PL is proved to be from localized exciton emission in a potential energy funnel. We can also introduce the localized strain in the QW film using a micropillar array of an electron beam resist and observe similar narrow emission lines. The method to achieve localized exciton states is a controllable way and it will further expand the application of traditional semiconductor QWs in optical quantum devices.
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Hyink, Otto, Philip A. Wescombe, Mathew Upton, Nancy Ragland, Jeremy P. Burton, and John R. Tagg. "Salivaricin A2 and the Novel Lantibiotic Salivaricin B Are Encoded at Adjacent Loci on a 190-Kilobase Transmissible Megaplasmid in the Oral Probiotic Strain Streptococcus salivarius K12." Applied and Environmental Microbiology 73, no. 4 (December 28, 2006): 1107–13. http://dx.doi.org/10.1128/aem.02265-06.
Повний текст джерелаАнотація:
ABSTRACT The commercial probiotic Streptococcus salivarius strain K12 is the prototype of those S. salivarius strains that are the most strongly inhibitory in a standardized test of streptococcal bacteriocin production and has been shown to produce the 2,368-Da salivaricin A2 (SalA2) and the 2,740-Da salivaricin B (SboB) lantibiotics. The previously uncharacterized SboB belongs to the type AII class of lantibiotic bacteriocins and is encoded by an eight-gene cluster. The genetic loci encoding SalA2 and SboB in strain K12 have been fully characterized and are localized to nearly adjacent sites on pSsal-K12, a 190-kb megaplasmid. Of 61 strongly inhibitory strains of S. salivarius, 19 (31%) were positive for the sboB structural gene. All but one (strain NR) of these 19 strains were also positive for salA2, and in each of these cases of double positivity, the two loci were separated by fewer than 10 kb. This is the first report of a single streptococcus strain producing two distinct lantibiotics.
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Jensen, L. A., and B. D. Schwartz. "A novel guinea pig macrophage-specific polymorphic molecule. II. Biochemical analysis of the polymorphism." Journal of Immunology 140, no. 4 (February 15, 1988): 1206–11. http://dx.doi.org/10.4049/jimmunol.140.4.1206.
Повний текст джерелаАнотація:
Abstract We have identified a macrophage-specific molecule, termed gp98, which has a m.w. of 98,000, is encoded by a gene not linked to the guinea pig lymphocyte antigen complex, is highly immunogenic, and displays a serologic polymorphism among several inbred guinea pig strains. The gp98 molecule was biochemically analyzed to identify a basis for the serologically detected polymorphism. The molecule was demonstrated to be a glycoprotein containing N-linked oligosaccharides. The strain 2 serologic variant, gp98-2, migrated with an apparent m.w. approximately 2500 more than did the strain 13 variant gp98-13. This differential migration was observed in a (strain 2 X strain 13) F1 animal, and persisted after neuraminidase and endoglycosidase F treatment, and after reduction. Trypsin and endoproteinase Lys-C digestion localized the biochemical basis of the polymorphism to the peptide portion of the molecule. Biochemical analysis of the gp98 molecules from five different inbred strains indicated that only two biochemical variants correlating with the serologic variants existed among the five strains.
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Guo, Yifan, and Charles G. Woychik. "Thermal Strain Measurements of Solder Joints in Second Level Interconnections Using Moire Interferometry." Journal of Electronic Packaging 114, no. 1 (March 1, 1992): 88–92. http://dx.doi.org/10.1115/1.2905446.
Повний текст джерелаАнотація:
Low cycle fatigue of solder joints is one of the major kinds of failures in second level interconnections of an electronic package. The fatigue failure is caused by thermal strains which are created from a mismatch of coefficients of thermal expansion (CTE) that occurs between two levels of packaging. As the package approaches smaller dimensions, measurements of thermal strains in the solder interconnections become very difficult. In this paper, moire interferometry technique was applied to evaluate the thermal strains in the second level interconnections for both conventional pin-in-hole (PIH) packages and surface mount components. The coefficient of thermal expansion of each component was measured. Thermal strain distributions in the solder interconnections were determined, and reliability issues were discussed. The strains in solder joints of the PIH components were much higher than those of the stacked surface mount components. Even though the surface mount components had a lower inherent strength, their overall mechanical reliability was much higher since they had practically no localized strain concentrations.
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McCrea, Kirk W., Jennifer L. St. Sauver, Carl F. Marrs, Daniel Clemans, and Janet R. Gilsdorf. "Immunologic and Structural Relationships of the Minor Pilus Subunits among Haemophilus influenzaeIsolates." Infection and Immunity 66, no. 10 (October 1, 1998): 4788–96. http://dx.doi.org/10.1128/iai.66.10.4788-4796.1998.
Повний текст джерелаАнотація:
ABSTRACT Two proteins, HifD and HifE, have been identified as structural components of Haemophilus influenzae pili. Both are localized at the pilus tip, and HifE appears to mediate pilus adherence to host cells. In this study we examined the immunologic and structural diversity of these pilus subunits among type b H. influenzae (Hib) and nontypeable H. influenzae (NTHI) strains. Western immunoblot analysis revealed that antibodies directed against the C terminus of HifD and HifE from Hib strain Eagan bound to HifD and HifE proteins, respectively, of all piliated Hib and NTHI strains tested. Whole-cell enzyme-linked immunosorbent assays showed that antibodies specific for native HifD or HifE of strain Eagan also bound to all piliated Hib strains but did not bind to the piliated NTHI strains. Antibodies against HifE of strain Eagan inhibited the binding of Hib to human erythrocytes but did not inhibit the binding of NTHI strains. Restriction fragment length polymorphism (RFLP) analysis was used to determine strain-to-strain structural differences withinhifD and hifE genes, either by PCR or by nucleotide sequence analysis. DNA and derived amino acid sequence analyses of HifD and HifE confirmed the uniqueness of the RFLP types. The hifD and hifE genes of all type b strains showed identical restriction patterns. Analysis of hifD andhifE genes from the NTHI strains, however, revealed seven unique RFLP patterns, suggesting that these genes encode proteins with diverse primary structures. These results indicate that HifD and HifE are immunologically and structurally similar among the Hib strains but vary among the NTHI strains.
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Bian, Xiaohui, Ahmed A. Saleh, Peter A. Lynch, Christopher H. J. Davies, Azdiar A. Gazder, and Elena V. Pereloma. "An in situ synchrotron study of the localized B2↔B19′ phase transformation in an Ni–Ti alloy subjected to uniaxial cyclic loading–unloading with incremental strains." Journal of Applied Crystallography 53, no. 2 (February 18, 2020): 335–48. http://dx.doi.org/10.1107/s1600576720000370.
Повний текст джерелаАнотація:
High-resolution in situ synchrotron X-ray diffraction was applied to study a cold-drawn and solution-treated 56Ni–44Ti wt% alloy subjected to uniaxial cyclic loading–unloading with incremental strains. The micro-mechanical behaviour associated with the partial and repeated B2↔B19′ phase transformation at the centre of the sample gauge length was studied with respect to the macroscopic stress–strain response. The lattice strains of the (110)B2 and different B19′ grain families are affected by (i) the transformation strain, the load-bearing capacity of both phases and the strain continuity maintained at/near the B2–B19′ interfaces at the centre of the gauge length, and (ii) the extent of transformation along the gauge length. With cycling and incremental strains (i) the elastic lattice strain and plastic strain in the remnant (110)B2 grain family gradually saturate at early cycles, whereas the plastic strain in the B19′ phase continues to increase. This contributes to accumulation of residual strains (degradation in superelasticity), greater non-linearity and change in the shape of the macroscopic stress–strain curve from plateau type to curvilinear elastic. (ii) The initial 〈111〉B2 fibre texture transforms to [120]B19′, [130]B19′, [150]B19′ and [010]B19′ orientations. Further increase in the applied strain with cycling results in the development of [130]B19′, [102]B19′, [102]B19′, [100]B19′ and [100]B19′ orientations.
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Soares, G. C., N. I. Vázquez-Fernández, and M. Hokka. "Thermomechanical Behavior of Steels in Tension Studied with Synchronized Full-Field Deformation and Temperature Measurements." Experimental Techniques 45, no. 5 (February 19, 2021): 627–43. http://dx.doi.org/10.1007/s40799-020-00436-y.
Повний текст джерелаАнотація:
AbstractDespite tensile testing being commonly used for investigating the mechanical behavior of materials, the occurrence of heterogeneous strain and increasing temperature at high strain rates make the experiment much more complex. This work presents a method integrating synchronous full-field stereo Digital Image Correlation (DIC) and Infrared Thermography (IRT). This method enabled high resolution investigations of the development of local temperatures and strains of the specimen during tensile loading of four steels at strain rates ranging from 2.5·10−4 to 900 s−1. The tests were monitored by a stereo setup of optical cameras and an infrared camera. Data acquisition was synchronized, and a pinhole camera model was used to translate the images from all cameras to the same three-dimensional space. The displacement vector fields from DIC were subtracted from the IRT images to represent the temperature maps in a Lagrangian coordinate system. The overall thermomechanical response of the materials was shown as 3D waterfall plots, which represent localized strain and temperature as a function of position and engineering strain. The results show that temperature increased homogeneously during uniform deformation at higher strain rates (10−2-900 s−1) and increased markedly with the onset of necking on the region of localized strain. At these strain rates, the localized increase of strain and temperature during necking were observed at the same global engineering strain and position, evidencing the spatial and temporal synchronization. The described method was used to accurately investigate the evolution of localized strain and temperature in both low and high strain rate regime.
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Zheng, Liyuan, Shan Wei, Meiling Wu, Xuehao Zhu, Xiaoming Bao, Jin Hou, Weifeng Liu, and Yu Shen. "Improving Xylose Fermentation in Saccharomyces cerevisiae by Expressing Nuclear-Localized Hexokinase 2." Microorganisms 8, no. 6 (June 5, 2020): 856. http://dx.doi.org/10.3390/microorganisms8060856.
Повний текст джерелаАнотація:
Understanding the relationship between xylose and the metabolic regulatory systems is a prerequisite to enhance xylose utilization in recombinant S. cerevisiae strains. Hexokinase 2 (Hxk2p) is an intracellular glucose sensor that localizes to the cytoplasm or the nucleus depending on the carbon source. Hxk2p interacts with Mig1p to regulate gene transcription in the nucleus. Here, we investigated the effect of nucleus-localized Hxk2p and Mig1p on xylose fermentation. The results show that the expression of HXK2S14A, which encodes a constitutively nucleus-localized Hxk2p, increased the xylose consumption rate, the ethanol production rate, and the ethanol yield of the engineered yeast strain by 23.5%, 78.6% and 42.6%, respectively. The deletion of MIG1 decreased xylose utilization and eliminated the positive effect of Hxk2p. We then performed RNA-seq and found that the targets of Hxk2pS14A on xylose were mainly genes that encode RNA-binding proteins. This is very different from the known targets of Mig1p and supports the notion that the Hxk2p-Mig1p interaction is abolished in the presence of xylose. These results will improve our understanding of the interrelation between the Snf1p-Mig1p-Hxk2p glucose signaling pathway and xylose utilization in S. cerevisiae and suggests that the expression of HXK2S14A could be a viable strategy to improve xylose utilization.
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Curland, Rebecca D., Liangliang Gao, Cory D. Hirsch, and Carol A. Ishimaru. "Localized Genetic and Phenotypic Diversity of Xanthomonas translucens Associated With Bacterial Leaf Streak on Wheat and Barley in Minnesota." Phytopathology® 110, no. 2 (February 2020): 257–66. http://dx.doi.org/10.1094/phyto-04-19-0134-r.
Повний текст джерелаАнотація:
Bacterial leaf streak (BLS) of wheat and barley has been a disease of increasing concern in the Upper Midwest over the past decade. In this study, intra- and interfield genetic and pathogenic diversity of bacteria causing BLS in Minnesota was evaluated. In 2015, 89 strains were isolated from 100 leaf samples collected from two wheat and two barley fields naturally infected with BLS. Virulence assays and multilocus sequence alignments of four housekeeping genes supported pathovar identifications. All wheat strains were pathogenic on wheat and barley and belonged to the same lineage as the Xanthomonas translucens pv. undulosa-type strain. All barley strains were pathogenic on barley but not on wheat. Three lineages of barley strains were detected. The frequency and number of sequence types of each pathovar varied within and between fields. A significant population variance was detected between populations of X. translucens pv. undulosa collected from different wheat fields. Population stratification of X. translucens pv. translucens was not detected. Significant differences in virulence were detected among three dominant sequence types of X. translucens pv. undulosa but not those of X. translucens pv. translucens. Field trials with wheat and barley plants inoculated with strains of known sequence type and virulence did not detect significant race structures within either pathovar. Knowledge of virulence, sequence types, and population structures of X. translucens on wheat and barley can support studies on plant–bacterial interactions and breeding for BLS disease resistance.
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Shianna, Kevin V., Russell Rytter, and Jonathan G. Spanier. "Randomly Amplified Polymorphic DNA PCR Analysis of Bovine Cryptosporidium parvum Strains Isolated from the Watershed of the Red River of the North." Applied and Environmental Microbiology 64, no. 6 (June 1, 1998): 2262–65. http://dx.doi.org/10.1128/aem.64.6.2262-2265.1998.
Повний текст джерелаАнотація:
ABSTRACT Cryptosporidium parvum is a protozoan parasite that causes the disease cryptosporidiosis in a variety of mammals, including neonatal calves and humans. Millions of oocysts are shed during acute cryptosporidiosis, and zoonotic transmission is inferred, though not proven, to be a general phenomenon. Very little is known about the degree of strain variation exhibited by bovine and human isolates, though such knowledge would enable the amount of bovine-to-human transmission to be more precisely analyzed. This research was initiated to determine whether variations exist among bovine strains isolated from a localized geographic area, the watershed of the Red River of the North. Sixteen strains were isolated and compared to each other and to two human and two calf strains from Australia by randomly amplified polymorphic DNA PCR. A statistical analysis of the data indicated that the isolates belonged to four different groups of strains.
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Minardo, Aldo, Ester Catalano, Agnese Coscetta, Giovanni Zeni, Lei Zhang, Caterina Di Maio, Roberto Vassallo, et al. "Distributed Fiber Optic Sensors for the Monitoring of a Tunnel Crossing a Landslide." Remote Sensing 10, no. 8 (August 15, 2018): 1291. http://dx.doi.org/10.3390/rs10081291.
Повний текст джерелаАнотація:
This work reports on the application of a distributed fiber-optic strain sensor for long-term monitoring of a railway tunnel affected by an active earthflow. The sensor has been applied to detect the strain distribution along an optical fiber attached along the two walls of the tunnel. The experimental results, relative to a two-year monitoring campaign, demonstrate that the sensor is able to detect localized strains, identify their location along the tunnel walls, and follow their temporal evolution.
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Sikorski, Johannes, Jorge Lalucat, and Wilfried Wackernagel. "Genomovars 11 to 18 of Pseudomonas stutzeri, identified among isolates from soil and marine sediment." International Journal of Systematic and Evolutionary Microbiology 55, no. 5 (September 1, 2005): 1767–70. http://dx.doi.org/10.1099/ijs.0.63535-0.
Повний текст джерелаАнотація:
Amongst 440 strains of Pseudomonas stutzeri isolated from soil and marine sediment for a population genetic study, eight strains were each presumed to represent a novel genomic group and were compared with each other and to reference strains of P. stutzeri genomovars 1 to 10 and other Pseudomonas species by DNA–DNA hybridization, 16S rRNA and internally transcribed 16S–23S rRNA spacer region (ITS1) sequences and basic physiological properties defining the species. While 16S rRNA and ITS1 gene sequences positioned the eight strains within the phylogenetic branch of P. stutzeri, the DNA–DNA hybridizations with reference strains of the 10 described genomovars and among the novel strains were generally below 70 %, which is the threshold for species and genomovar differentiation. Since the physiological properties studied in the eight strains fitted the profile of P. stutzeri, eight new genomovars of P. stutzeri, numbered 11 to 18, are proposed, with strains 28a50, 28a39, 28a22, 28a3, 4C29, 24a13, 24a75 and MT-1 being the reference strains. The highly transformable reference strain 28a3 of genomovar 14 had a localized 16S rRNA gene sequence tag characteristic of genomovar strains 2 and 3, suggesting a possible horizontal gene transfer event involving part of the 16S rRNA gene.
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Nuñez, J. E., and G. Glinka. "Analysis of non-localized creep induced strains and stresses in notches." Engineering Fracture Mechanics 71, no. 12 (August 2004): 1791–803. http://dx.doi.org/10.1016/s0013-7944(03)00208-x.
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Rollof, J., S. Å. HedstrÖM, and P. Nilsson-Ehle. "LIPOLYTIC ACTIVITY OF STAPHYLOCOCCUS AUREUS STRAINS FROM DISSEMINATED AND LOCALIZED INFECTIONS." Acta Pathologica Microbiologica Scandinavica Series B: Microbiology 95B, no. 1-6 (August 15, 2009): 109–13. http://dx.doi.org/10.1111/j.1699-0463.1987.tb03096.x.
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Schwarcz, Attila, Oliver Natt, Takashi Watanabe, Susann Boretius, Jens Frahm, and Thomas Michaelis. "Localized proton MRS of cerebral metabolite profiles in different mouse strains." Magnetic Resonance in Medicine 49, no. 5 (April 15, 2003): 822–27. http://dx.doi.org/10.1002/mrm.10445.
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Odinokov, G. N., and K. A. Nikiforov. "Detection of New Variable DNA Loci That Distinguish Medievalis Biovar Strains of Plague Agent from the Strains of Other Biovars." Problems of Particularly Dangerous Infections, no. 4(114) (August 20, 2012): 47–48. http://dx.doi.org/10.21055/0370-1069-2012-4-47-48.
Повний текст джерелаАнотація:
Variable chromosome loci have been searched, that differentiate Yersinia pestis strains of medievalis from antiqua biovars. The strains of medievalis biovar are shown to possess two deletions – 183 and 70 bps. The first deletion, localized in the inter-gene region aceA – aceK is present in the majority of medievalis biovar strains, the second one, in the gene y1694 , is determined in all medievalis biovar strains isolated in the territory of Russia and neighboring countries.
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Toribio, Jesús, Miguel Lorenzo, and Leticia Aguado. "Innovative Design of Residual Stress and Strain Distributions for Analyzing the Hydrogen Embrittlement Phenomenon in Metallic Materials." Materials 15, no. 24 (December 19, 2022): 9063. http://dx.doi.org/10.3390/ma15249063.
Повний текст джерелаАнотація:
Round-notched samples are commonly used for testing the susceptibility to hydrogen embrittlement (HE) of metallic materials. Hydrogen diffusion is influenced by the stress and strain states generated during testing. This state causes hydrogen-assisted micro-damage leading to failure that is due to HE. In this study, it is assumed that hydrogen diffusion can be controlled by modifying such residual stress and strain fields. Thus, the selection of the notch geometry to be used in the experiments becomes a key task. In this paper, different HE behaviors are analyzed in terms of the stress and strain fields obtained under diverse loading conditions (un-preloaded and preloaded causing residual stress and strains) in different notch geometries (shallow notches and deep notches). To achieve this goal, two uncoupled finite element (FE) simulations were carried out: (i) a simulation by FE of the loading sequences applied in the notched geometries for revealing the stress and strain states and (ii) a simulation of hydrogen diffusion assisted by stress and strain, for estimating the hydrogen distributions. According to results, hydrogen accumulation in shallow notches is heavily localized close to the wire surface, whereas for deep notches, hydrogen is more uniformly distributed. The residual stress and plastic strains generated by the applied preload localize maximum hydrogen concentration at deeper points than un-preloaded cases. As results, four different scenarios are established for estimating “a la carte” the HE susceptibility of pearlitic steels just combining two notch depths and the residual stress and strain caused by a preload.
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Bamouh, Zahra, Jihane Hamdi, Siham Fellahi, Slimane Khayi, Mohammed Jazouli, Khalid Omari Tadlaoui, Ouafaa Fassi Fihri, Eeva Tuppurainen, and Mehdi Elharrak. "Investigation of Post Vaccination Reactions of Two Live Attenuated Vaccines against Lumpy Skin Disease of Cattle." Vaccines 9, no. 6 (June 8, 2021): 621. http://dx.doi.org/10.3390/vaccines9060621.
Повний текст джерелаАнотація:
Lumpy skin disease virus (LSDV) causes an economically important disease in cattle. The only method for successful control is early diagnosis and efficient vaccination. Adverse effects of vaccination such as local inflammation at the injection site and localized or generalized skin lesions in some vaccinated animals have been reported with live vaccines. The aim of this work was to compare the safety of two lumpy skin disease (LSD) vaccine strains, Kenyan (Kn) Sheep and Goat Pox (KSGP O-240) and LSDV Neethling (Nt) strain, and to determine the etiology of the post-vaccination (pv) reactions observed in cattle. Experimental cattle were vaccinated under controlled conditions with Nt- and KSGP O-240-based vaccines, using two different doses, and animals were observed for 3 months for any adverse reactions. Three out of 45 cattle vaccinated with LSDV Nt strain (6.7%) and three out of 24 cattle vaccinated with Kn strain (12.5%) presented LSD-like skin nodules, providing evidence that the post-vaccination lesions may not be strain-dependent. Lesions appeared 1–3 weeks after vaccination and were localized in the neck or covering the whole body. Animals recovered after 3 weeks. There is a positive correlation between the vaccine dose and the appearance of skin lesions in vaccinated animals; at the 105 dose, 12% of the animals reacted versus 3.7% at the 104 dose. Both strains induced solid immunity when protection was measured by neutralizing antibody seroconversion.
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BONIFAZ, E. A., and N. L. RICHARDS. "STRESS–STRAIN EVOLUTION IN CAST IN-738 SUPERALLOY SINGLE FUSION WELDS." International Journal of Applied Mechanics 02, no. 04 (December 2010): 807–26. http://dx.doi.org/10.1142/s1758825110000767.
Повний текст джерелаАнотація:
A three-dimensional finite element elastic–plastic model was developed to study localized plastic strains and residual stresses that exist in a body that has previously been subjected to nonuniform temperature changes. The mechanical model was used to compute the evolution of plastic strains and residual stresses of welded material. The thermal gradient histories calculated during the GTA welding of cast IN-738LC alloys were imposed as load conditions on structural calculations. It can be clearly seen that at constant heat input, the level of plastic strains and the level of residual (Mises) stresses increase with welding speed. The model predicts highest residual stresses in regions of highest elastic strains, in agreement with conventional phenomenological material models where the macroscopic residual stress is always directly related to the macroscopic elastic strain. The highest residual stresses are located at the fusion line (where coarser dendrite secondary arm spacing exist); and the highest plastic strains are located at centerline (where finer dendrite secondary arm spacing exist). The calculations were performed using ABAQUS® FE code on the basis of a time-increment Lagrangian formulation.
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Was, G. S., B. Alexandreanu, and J. Busby. "Localized Deformation Induced IGSCC and IASCC of Austenitic Alloys in High Temperature Water." Key Engineering Materials 261-263 (April 2004): 885–902. http://dx.doi.org/10.4028/www.scientific.net/kem.261-263.885.
Повний текст джерелаАнотація:
Grain boundary properties are known to affect the intergranular stress corrosion cracking (IGSCC) and irradiation assisted stress corrosion cracking behavior of austenitic alloys in high temperature water. However, it is only recently that sufficient evidence has accumulated to show that the disposition of deformation in and near the grain boundary plays a key role in intergranular cracking. Grain boundaries that can transmit strain to adjacent grains can relieve stresses without undergoing localized deformation. Grain boundaries that cannot transmit strain will either experience high stresses or high strains. High stresses can lead to wedge-type cracking and sliding can lead to rupture of the protective oxide film. These processes are also applicable to irradiated materials in which the deformation can become highly localized in the form of dislocation channels and deformation twins. These deformation bands conduct tremendous amounts of strain to the grain boundaries. The capability of a boundary to transmit strain to a neighboring grain will determine its propensity for cracking, analogous to that in unirradiated metals. Thus, IGSCC in unirradiated materials and IASCC in irradiated materials are governed by the same local processes of stress and strain accommodation at the boundary.
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Kukavica-Ibrulj, Irena, Alessandra Bragonzi, Moira Paroni, Craig Winstanley, François Sanschagrin, George A. O'Toole, and Roger C. Levesque. "In Vivo Growth of Pseudomonas aeruginosa Strains PAO1 and PA14 and the Hypervirulent Strain LESB58 in a Rat Model of Chronic Lung Infection." Journal of Bacteriology 190, no. 8 (December 14, 2007): 2804–13. http://dx.doi.org/10.1128/jb.01572-07.
Повний текст джерелаАнотація:
ABSTRACT Pseudomonas aeruginosa chronic lung infections are the major cause of morbidity and mortality in cystic fibrosis (CF) patients. The P. aeruginosa strains PAO1 and PA14 were compared with the Liverpool epidemic strain LESB58 to assess in vivo growth, infection kinetics, and bacterial persistence and localization within tissues in a rat model of chronic lung infection. The three P. aeruginosa strains demonstrated similar growth curves in vivo but differences in tissue distribution. The LESB58 strain persisted in the bronchial lumen, while the PAO1 and PA14 strains were found localized in the alveolar regions and grew as macrocolonies after day 7 postinfection. Bacterial strains were compared for swimming and twitching motility and for the production of biofilm. The P. aeruginosa LESB58 strain produced more biofilm than PAO1 and PA14. Competitive index (CI) analysis of PAO1, PA14, and LESB58 in vivo indicated CI values of 0.002, 0.0002, and 0.14 between PAO1-PA14, PAO1-LESB58, and LESB58-PA14, respectively. CI analysis comparing the in vivo growth of the PAO1 ΔPA5441 mutant and four PA14 surface attachment-defective (sad) mutants gave CI values 10 to 1,000 times lower in competitions with their respective wild-type strains PAO1 and PA14. P. aeruginosa strains studied in the rat model of chronic lung infection demonstrated similar in vivo growth but differences in virulence as shown with a competitive in vivo assay. These differences were further confirmed with biofilm and motility in vitro assays, where strain LESB58 produced more biofilm but had less capacity for motility than PAO1 and PA14.