Thermomagnetic behavior of a semiconductor material heated by pulsed excitation based on the fourth-order MGT photothermal model

This article proposes a photothermal model to reveal the thermo-magneto-mechanical properties of semiconductor materials, including coupled diffusion equations for thermal conductivity, elasticity, and excess carrier density. The proposed model is developed to account for the optical heating that occurs through the semiconductor medium. The Moore–Gibson–Thompson (MGT) equation of the fourth-order serves as the theoretical framework to establish the photothermal model. It is well-known that the optical and heat transfer properties of such materials behave as random functions of photoexcited-carrier density; therefore, the current model is remarkably more reliable compared to the earlier closed-form theories which are limited to a single form. The constructed theoretical framework is able to investigate the magneto-photo-thermoelastic problems in a semiconductor medium due to laser pulse excitation as a case study. Some parametric studies are used to exhibit the impact of thermal parameters, electromagnetic fields, laser pulses and thermoelectric coupling factors on the thermomagnetic behavior of physical variables. Finally, several numerical examples have been presented to draw the distributions of the examined field variables

TEMPERATURE-DEPENDENT PHYSICAL CHARACTERISTICS OF THE ROTATING NONLOCAL NANOBEAMS SUBJECT TO A VARYING HEAT SOURCE AND A DYNAMIC LOAD

In this article, the influence of thermal conductivity on the dynamics of a rotating nanobeam is established in the context of nonlocal thermoelasticity theory. To this end, the governing equations are derived using generalized heat conduction including phase lags on the basis of the Euler–Bernoulli beam theory. The thermal conductivity of the proposed model linearly changes with temperature and the considered nanobeam is excited with a variable harmonic heat source and exposed to a time-dependent load with exponential decay. The analytic solutions for bending moment, deflection and temperature of rotating nonlocal nanobeams are achieved by means of the Laplace transform procedure. A qualitative study is conducted to justify the soundness of the present analysis while the impact of nonlocal parameter and varying heat source are discussed in detail. It also shows the way in which the variations of physical properties due to temperature changes affect the static and dynamic behavior of rotating nanobeams. It is found that the physical fields strongly depend on the nonlocal parameter, the change of the thermal conductivity, rotation speed and the mechanical loads and, therefore, it is not possible to neglect their effects on the manufacturing process of precise/intelligent machines and devices

Serological diagnosis of Helicobacter pylori infection in patients with a polycystic ovary syndrome

Background: Polycystic Ovary Syndrome (PCOS) is the most common endocrine disorder in 4 - 6 of women in the reproductive age and is a common cause of infertility. Even though the number of investigations is scarce, studies show that Helicobacter pylori infection may influence reproduction. Objectives: The purpose of this study was to determine and compare the levels of H. pylori specific antibodies IgA, IgG and anti-CagA at both PCOS and non-PCOS women with their spouses using the serological test. Patients and Methods: In this cross-sectional study, 127 women with their spouses (age range, 30 - 60 years) were selected. These patient were referred to infertility center of Shariati Hospital in Tehran, Iran, with a diagnostic criteria of PCOS based on Androgen Excess Society (AES). The specific antibodies of IgA, IgG and anti-CagA were measured using the commercial Enzyme-Linked Immunosorbent Assay (ELISA) kit. Results: The positive titers of H. pylori antibodies IgA, IgG and anti-CagA in the PCOS group were 45 (35), 79 (62) and 77 (60.5), respectively, while in non-PCOS group were 38 (30), 76 (60) and 50 (39.5), respectively. The sera positive for IgA, IgG and anti-CagA antibodies in spouses of the non-PCOS group were 38 (30), 84 (66) and 79 (62) respectively, but in spouses of the PCOS group were 51 (40), 83 (66) and 48 (38), respectively. The results showed that H. pylori infection probably did not affect infertility or reproduction. Conclusions: Findings of this study demonstrate no significant difference between levels of H. pylori specific antibodies of IgA, IgG, anti-CagA and the presence of PCOS disorders, and also indicate that serologic testing is a sensitive method for the detection of H. pylori antibodies. The high prevalence of H. pylori positive antibody levels in both PCOS and non-PCOS patients can be probably associated with the high frequency of H. pylori infection. © 2015, Infectious Diseases and Tropical Medicine Research Center

Virulence factors and antimicrobial resistance in uropathogenic escherichia coli strains isolated from cystitis and pyelonephritis

Background/aim: The aim of this study was to investigate the prevalence of virulence genes as well as patterns of antibiotic resistance in cystitis and pyelonephritis uropathogenic Escherichia coli (UPEC) isolates. Materials and methods: Two hundred UPEC isolates were collected from hospitalized patients with pyelonephritis (n = 50) and cystitis (n = 150) in Shafa Hospital in Iran. Antimicrobial susceptibility and ESBL production were determined with confirmatory tests. Polymerase chain reaction assay was performed to determine the prevalence of virulence genes in UPEC strains. Results: Of a total 200 UPEC isolates, the highest and lowest resistance rates to antibiotics were for cephalexin (74) and nitrofurantoin (9), respectively. Of these isolates, 72 (36) and 128 (64) strains were ESBL-positive and ESBL-negative, respectively. The frequency of fimH, papC, and hly was 64, 38, and 12, respectively. The most commonly identified virulence gene in ESBL-positive and ESBL-negative strains was fimH 46 (23) and 86 (43), respectively. The hlyA gene was more prevalent among patients with pyelonephritis than cystitis. Conclusion: The frequency of virulence genes was not significantly different between pyelonephritis and cystitis UPEC strains in the studied patients, but the prevalence rates of hlyA and papC genes were higher among UPEC strains isolated from inpatients compared to outpatients; hence, they could be considered as useful targets for prophylactic interventions. © TUBİTAK

Fosfomycin: Mechanisms and the increasing prevalence of resistance

There are challenges regarding increased global rates of microbial resistance and the emergence of new mechanisms that result in microorganisms becoming resistant to antimicrobial drugs. Fosfomycin is a broad-spectrum bactericidal antibiotic effective against Gram-negative and certain Gram-positive bacteria, such as Staphylococci, that interfere with cell wall synthesis. During the last 40 years, fosfomycin has been evaluated in a wide range of applications and fields. Although numerous studies have been done in this area, there remains limited information regarding the prevalence of resistance. Therefore, in this review, we focus on the available data concerning the mechanisms and increasing resistance regarding fosfomycin. © 2019 The Authors

Prevalence and antimicrobial susceptibility pattern of toxigenic clostridium difficistrains isolated in iran

Background/aim: Clostridium difficile is a frequent cause of nosocomial infections and has become a major public health concern in developed nations. In the present study, the prevalence and antimicrobial susceptibility pattern of toxigenic C. difficile strains isolated in Iran were investigated. Materials and methods: Between June 2016 and May 2017, 2947 inpatient fecal samples were taken from symptomatic adult hospitalized patients in different units of 32 care facilities in Tehran, Iran. C. difficile strains were identified by microbiological/biochemical methods. Susceptibility to 20 antimicrobials was measured by E-test method. Toxin-specific immunoassays and cytotoxicity assays were used to determine in vitro toxin production. Results: Out of 2947 fecal samples, 538 (18.25) C. difficile isolates were obtained among those with suspected CDI. In E-test method, all C. difficile isolates were susceptible to fidaxomicin, vancomycin, amoxicillin/clavulanate, and meropenem and were resistant to penicillin G. The prevalence of multidrug resistant C. difficile was 69.33 (373/538). Among 538 C. difficile, 147 (27.32), 169 (31.41), and 222 (41.26) isolates were TcdA+/TcdB+, TcdA-/TcdB+, and TcdA-/TcdB-, respectively. Conclusion: The results evidently support the hypothesis of a probable role of toxigenic strains of C. difficile in developing gastrointestinal complaints in patients with diarrhea. © TUBİTAK

High pressure gas flow, storage, and displacement in fractured rock-Experimental setup development and application.

This paper presents the design, development, and application of a laboratory setup for the experimental investigations of gas flow and reactions in a fractured rock. The laboratory facility comprises (i) a high pressure manometric sorption apparatus, where equilibrium and kinetic phenomena of adsorption and desorption can be examined, (ii) a high pressure triaxial core flooding system where the chemical reactive transport properties or processes can be explored, and (iii) an ancillary system including pure and mixed gas supply and analysis units. Underground conditions, in terms of pore pressure, confining pressure, and temperature, can be replicated using the triaxial core flooding system developed for depths up to 2 km. Core flooding experiments can be conducted under a range of gas injection pressures up to 20 MPa and temperatures up to 338 K. Details of the design considerations and the specification for the critical measuring instruments are described. The newly developed laboratory facility has been applied to study the adsorption of N2, CH4, and CO2 relevant to applications in carbon sequestration in coal and enhanced coalbed methane recovery. Under a wide range of pressures, the flow of helium in a core sample was studied and the evolution of absolute permeability at different effective stress conditions has been investigated. A comprehensive set of high resolution data has been produced on anthracite coal samples from the South Wales coalfield, using the developed apparatus. The results of the applications provide improved insight into the high pressure flow and reaction of various gas species in the coal samples from the South Wales coalfield