The effect of onboard passengers’ seating arrangement on the vertical ride comfort of a high-speed railway vehicle

This research is concerned with the impact of onboard passengers’ seating arrangement on the carbody flexural vibrations of a high-speed railway vehicle. In this regard, the previously developed passenger body-seat models are used to consider the dynamic influence of the passengers. The carbody is modeled using the Euler–Bernoulli beam model to evaluate its flexural deformation. The frequency-domain analysis demonstrates that the carbody behaves almost like a rigid body when the vehicle is full of passengers. It is established that the passengers' presence causes a 31% enhancement of the ride quality determined based on EN 12299 standard for a fully occupied vehicle compared with an empty car. A scaled model of a ratio of 1:24.5 of the Shinkansen vehicle is constructed for validation purposes. The experimental results exhibit a similar trend as found by the simulations in terms of the impact of the passengers’ distribution on the carbody flexural vibrationsPostprint (author's final draft

Molecular detection of 16s rRNA, qacA / B, smr in Clinical Isolates of staphylococcus aureus methicillin resistance

Objectives: Disinfectants and antiseptics agents of the past were used for disinfect equipment and surfaces. In some cases, these substances ineffective by a series of specific efflux proteins that are present in bacteria. QqcA / B and smr such as most important genes those can be expression more efflux protein in strain of methicillin-resistant staphylococcus aureus (MRSA). The aim of this study was to investigate the genes qacA / B and smr is MRSA strains.Methods: 89 isolates from various clinical samples were early identified by biochemical test. Initial screening was performed by Cefoxitin disk diffusion (30 µg) and then detection of mecA, smr and qacA/B gens was done by polymerase chain reaction (PCR). Finally, were analyzed results by using chi-square tests and t-test.Results: Out of 89 staphylococcus aureus isolates, 59 isolates were identified methicillin-resistant by initial phenotype test. Among those, 50 isolates (17/56) have respectively mecA gene, 14 isolates (73/15) smr gene and 29 isolates (58/32) qacA / B gene. Using by statistical tests and p.value test, was obtained the relationship between qacA / B and mecA genes.Conclusions: According to the results of the studie of prevalence of genes in Zahedan and high frequency of MRSA strains, should pay more attention to the use of disinfectants agents

Molecular study of the blaZ Staphylococcus aureus gene isolated from clinical samples

Background: Bacterial resistants to beta-lactam antibiotics, are steadily expanding. Excessive consumption beta-lactam antibiotics in the treatment of related Staphylococcus aureus infections caused the emergence of beta-lactamase enzymes in strains. Identification and analysis of molecular characteristics of these strains can be effective to select on the appropriate antibiotic treatment.Materials and Methods: Initially, the isolates collected from clinical samples were screened by biochemical tests. After the whole Staphylococcus aureus resistance to beta-lactam antibiotics, were evaluated by used of molecular-specific primers.Results: Of 496 isolates obtained from different clinical samples, 147 isolates were identified as S. aureus. The highest resistance to the antibiotics had related to penicillin, Oxacillin, Cefocithin and the lowest resistance antibiotics had related to Vancomycin. From the 147 samples, 143 samples were blaZ genes that allocated to over 97 percent.Conclusion: According to the results of molecular tests, in the Zahedan spread of carrier-lactamase strains is very high. This would be to treat all staphylococcal infections of beta lactam antibiotics are not used as much as possible to the access to early treatment prevented the increase in resistant strains

Molecular Detection of Staphylococcus aureus Enterotoxin A and B Genes in Clinical Samples from Patients Referred to Health Centers in Zahedan City

Background: In this study we aimed at detecting the enterotoxin A and B gene of S. aureus in clinical samples of patients attending health centers in Zahedan using molecular methods. Materials and Methods: A cross-sectional study was carried out in which 40 samples of S. aureus were obtained from patients in a hospital in Zahedan, Iran. Following the biochemical tests, Identifications were confirmed by PCR with specific primers. Results: Among 40 clinical isolates of S. aureus the frequency of sea gene was 2% and the frequency of seb gene was 8% while the frequency of both sea+seb genes was 3%. Conclusion: Enterotoxin of S. aureus is one of the main factors in the pathogenesis of various diseases and production of these toxins increase the incidence of diseases, so rapid treatment is needed for enterotoxin gene expression

Comparison of Susceptibility Testing of E-test Strips with Cefoxitin and Oxacillin Disks in Identification of Methicillin-resistant Staphylococcus saprophyticus Strains

Background and Objectives: Over the years, Staphylococcus saprophyticus, in addition to becoming a serious pathogen, has become resistant to a wide range of antibiotics. Offering an inexpensive, rapid, and available method for identification of resistant bacteria can prevent the spread of infections caused by these bacteria. The aim of this study was to compare susceptibility testing of E-test strips with cefoxitin and oxacillin disks in identification of methicillin-resistant Staphylococcus saprophyticus strains in clinical samples. Methods: In this study, 590 isolates of Staphylococcus saprophyticus were isolated from different parts of treatment centers in Zahedan city. After confirmation of the genus of isolates, resistance to methicillin, was defined in 262 samples using cefoxitin 30 μg and oxacillin 1 μg antibiotic disks. To determine minimum inhibitory concentration, E-test strips and cefoxitin and oxacillin disks, were used. The mecA gene was identified by PCR and considered as gold standard. Results: Sensitivity of the test performed for cefoxitin and oxacillin antibiotics in the disk diffusion method, was 89.09% and 68.81%, respectively, and in the minimum inhibitory concentration, was 98.18% and 97.27%, respectively. Out of 262 samples, 110 were identified to be resistant to methicillin based on PCR assay. Conclusion: According to the findings of this study, oxacillin antibiotic disk showed acceptable sensitivity to determine methicillin-resistant Staphylococcus saprophyticus strains. Also, the methods based on the use of E-Test strips had the highest sensitivity and specificity

The coupled effects of bending and torsional flexural modes of a high-speed train car body on its vertical ride quality

This study is focused on the effects of bending and torsional flexural modes of the car body on the ride quality index of a high-speed train vehicle. The Euler–Bernoulli beam model is used to extract an analytical model for a high-speed train vehicle car body in order to investigate its bending and torsional flexural vibrations. The rigid model includes a car body, two bogie frames, and four wheelsets such that, each mass has three degrees of freedom including vertical displacement, pitch motion, and roll motion. The results obtained with the proposed analytical model are compared with experimental measurements of the car body response of a Shinkansen high-speed train. Moreover, it is determined that the bending and torsional flexural modes have significant effects on the vertical acceleration of the car body, particularly in the 9–15¿Hz frequency range. Furthermore, the ride quality index is calculated according to the EN 12299 standard and it is shown that the faster the train the more affected is the ride quality by the flexural modes. In addition, the effect of coherence between two rail irregularities (the right and the left rails) on the results of the simulation is investigated. The results conclude that if the irregularities are completely correlated the torsional flexural mode of the car body does not appear in the response. Also, the first bending flexural mode in such cases is more excited compared with the partially correlated or uncorrelated rail irregularities. Therefore, the ride quality index in completely correlated cases is higher than other case