115 resultados para Strain gages
em QUB Research Portal - Research Directory and Institutional Repository for Queen's University Belfast
Resumo:
This paper describes the design, commissioning, and evaluation of a ?ber-optic strain sensor system for the structural health monitoring of a prestressed concrete posttensioned box girder railway bridge in Mumbai, India, which shows a number of well-documented structural problems. Preliminary laboratory trials to design the most appropriate sensor system that could be readily transported and used on site are described, followed by a description of load tests on the actual bridge undertaken in collaboration with Indian Railways and using locomotives of known weight. Results from the load tests using the optical system are compared with similar results obtained using electrical resistance strain gages. Conclusions are summarized concerning the integrity of the structure and for the future use of the sensor system for monitoring bridges of this type. Crack width measurements obtained during the load tests are also described.
Resumo:
Ziebuhr W, Dietrich K, Trautmann M, Wilhelm M. Institut für Molekulare Infektionsbiologie, Würzburg, Germany. w.ziebuhr@mail.uni-wuerzburg.de During two clinical courses of shunt-associated meningitis in a 3-month-old child, five multiresistant S. epidermidis isolates were obtained and analyzed with regard to biofilm production and antibiotic susceptibility. Three S. epidermidis strains, which were initially isolated from the cerebrospinal fluid, produced biofilms on polystyrene tissue culture plates. Following antibiotic treatment and subsequent exchange of the shunt system, sterilization of the CSF was achieved. However, after three weeks a relapse of the infection occurred. The two S. epidermidis isolates obtained now were biofilm negative, but showed an identical resistance pattern as those from the previous infection, except that resistance to rifampicin and increased mininal inhibitory concentrations of aminoglycoside antibiotics had emerged. DNA fingerprinting by PFGE indicated the clonal origin of all isolates. However, some DNA rearrangements and differences in the IS256-specific hybridization patterns could be identified in the isolates from the second infection period that led to altered biofilm formation and increased expression of aminoglycoside resistance traits. The data evidence that variation of biofilm expression occurs in vivo during an infection and highlight the extraordinary genome flexibility of pathogenic S. epidermidis.
Resumo:
X-ray analysis of ferroelectric thin layers of Ba1/2Sr1/2TiO3 with different thicknesses reveals the presence of strain gradients across the films and allows us to propose a functional form for the internal strain profile. We use this to calculate the influence of strain gradient, through flexoelectric coupling, on the degradation of the ferroelectric properties of films with decreasing thickness, in excellent agreement with the observed behavior. This paper shows that strain relaxation can lead to smooth, continuous gradients across hundreds of nanometers, and it highlights the pressing need to avoid such strain gradients in order to obtain ferroelectric films with bulklike properties.
Modeling of the Behaviour of Semi-Crystalline Polypropylene at Elevated Strain Rate and Temperature.
Resumo:
The three-component naphthalene dioxygenase (NDO) enzyme system carries out the first step in the aerobic degradation of naphthalene to (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene by Rhodococcus sp. strain NCIMB 12038. The terminal oxygenase component (naphthalene 1,2-dioxygenase) that catalyzes this reaction belongs to the aromatic ring hydroxylating dioxygenase family and has been crystallized. These enzymes utilize a mononuclear nonheme iron centre to catalyze the addition of dioxygen to their respective substrates. In this reaction, two electrons, two protons and a dioxygen molecule are consumed. The Rhodococcus enzyme has only 33 and 29% sequence identity to the corresponding alpha- and beta-subunits of the NDO system of Pseudomonas putida NCIMB 9816-4, for which the tertiary structure has been reported. In order to determine the three-dimensional structure of the Rhodococcus NDO, diffraction-quality crystals have been prepared by the hanging-drop method. The crystals belongs to space group P2(1)2(1)2(1), with unit-cell parameters a = 87.5, b = 144, c = 185.6 Angstrom, alpha = beta = gamma = 90degrees, and diffract to 2.3 Angstrom resolution.
Resumo:
Objective: To investigate strain and mental health among family caregivers of oesophageal cancer patients and possible factors associated with caregiver mental health and strain.
Methods: Patients with oesophageal adenocarcinoma in Ireland were recruited into the FINBAR study (the main aim of which was to investigate factors influencing the Barrett's adenocarcinoma relationship). Carers completed the 13-item Caregiver Strain Index and the General Health Questionnaire-30 (GHQ) in the context of a brief interview with trained research staff that was undertaken separately from the interview with each cancer patient.
Results: Two hundred and twenty-seven patients participated in the FINBAR study. A total of 39 patients did not have a family carer or the carer could not be identified. Fifty percent (94/188) of carers completed the questionnaires. Mean (SD) scores for strain (6.65, SD=3.63) and mental health status (10.21, SD=7.30) were high and 71% of carers scored >5 on the GHQ indicating psychological distress. There was a statistically significant positive relationship between level of strain experienced by caregivers and the severity of their mental health status and whether or not carers scored >5 on the GHQ. Relatives were 1.70 (95% CI 1.34-2.15) times more likely to be defined as high scorers with each unit increase in the CSI score.
Conclusions: A significant proportion of caregivers experienced high levels of strain and psychological distress. There is a need to provide appropriate support and services targeted specifically at reducing the considerable strain of caring for patients with oesophageal cancer, particularly for carers of patients from lower socioeconomic groups.