Dirac Surface States and Nature of Superconductivity in Noncentrosymmetric BiPd

In non-magnetic bulk materials, inversion symmetry protects the spin degeneracy. If the bulk crystal structure lacks a centre of inversion, however, spin-orbit interactions lift the spin degeneracy, leading to a Rashba metal whose Fermi surfaces exhibit an intricate spin texture. In superconducting Rashba metals a pairing wavefunction constructed from these complex spin structures will generally contain both singlet and triplet character. Here we examine the possible triplet components of the order parameter in noncentrosymmetric BiPd, combining for the first time in a noncentrosymmetric superconductor macroscopic characterization, atomic-scale ultra-low-temperature scanning tunnelling spectroscopy, and relativistic first-principles calculations. While the superconducting state of BiPd appears topologically trivial, consistent with Bardeen-Cooper-Schrieffer theory with an order parameter governed by a single isotropic s-wave gap, we show that the material exhibits Dirac-cone surface states with a helical spin polarization.Comment: replaced by published versio

Multi-Drug Resistance Patterns in Bacteria Isolated from Various Sources upon Common Related Virulence Factors by PCR in Iran

Background: The current study was conducted to investigate the frequency of resistance in the bacteria isolated from various sources, in Shiraz, Iran. Acquisition of new resistance genes is an important factor in the increasing incidence of resistant strains. A critical feature of resistance gene transfer is their stability to adapt rapidly to a new host and make serious consequences. Methods: A total of 520 samples were chosen from human and animal sources in order to investigate the frequency of antibiotics resistance mobile genes using PCR assay. Results: The rates of 70%, 52%, 16.5%, 8.5%, 8%, 4%, 9.2% and 6.8% were confirmed for several genes including tetO, tetA, tetB, tetM, tetR, gyrA, blaz, and blaSHV, respectively. Our results have revealed a pool of mobile genetic elements in the bacteria isolated from various sources in Iran. Conclusion: Our findings indicated un-regulated use of antibiotics in the food production chains which require more investigation

Superconducting gap and vortex lattice of the heavy fermion compound CeCu_2Si_2

The order parameter and pairing mechanism for superconductivity in heavy fermion compounds are still poorly understood. Scanning tunneling microscopy and spectroscopy at ultra-low temperatures can yield important information about the superconducting order parameter and the gap structure. Here, we study the first heavy fermion superconductor, CeCu_2Si_2. Our data show the superconducting gap which is not fully formed and exhibits features that point to a multi-gap order parameter. Spatial mapping of the zero bias conductance in magnetic field reveals the vortex lattice, which allows us to unequivocally link the observed conductance gap to superconductivity in CeCu_2Si_2. The vortex lattice is found to be predominantly triangular with distortions at fields close to \sim 0.7 H_{c2}.Comment: 6 pages, 4 figures, revised version accepted for publication in PR

Prevalence of Antibiotic Residues in Milk Consumed in Iran: A Systematic Review and Meta-Analysis

Background: Improper use of antibiotics and not paying attention to withdrawal time causes antibiotics to enter the milk, which can cause allergies in humans and cause antibiotic-resistant pathogenic bacteria in the long run, so quality and hygienic milk control is essential.Methods: This study aimed to investigate the prevalence of antibiotic residues in milk as a systematic review and metaanalysis from 2004 to 2021 for 15 years in Iran. The data were collected from four international search databases, including PubMed, Scopus, Science Direct, and Google Scholar, and four Iranian databases, including SID, MagIran, Civilica, and IranDoc.Results: After reviews of 314 studies, 38 were finally selected, and the information was recorded and analyzed in Stata software. The results of this study show that the residual prevalence of antibiotics in milk using the screening method was 28% (CI: 0.34-0.22). The residual rates of antibiotics using enzymelinked immunosorbent assay (ELISA) and high-pressure liquid chromatography (HPLC) methods were 43% (CI: 0.26-0.59) and 27% (CI: 0.05-0.49), respectively.Conclusion: The data obtained from the meta-analysis show that despite various reports of a quantitative amount of antibiotic residue in milk, the average amount in the ELISA method was 16.98 ppm. Although the prevalence of antibiotics in Iran is relatively high, a quantitative amount is optimal. Also, since the use of antibiotics in livestock is almost inevitable, proper withdrawal time of antibiotics can play an important role in preventing the release of antibiotic residues in milk

COVID-19 Vaccination Among Diverse Population Groups in the Northern Governorates of Iraq

Objectives: The present study was carried out to investigate COVID-19 vaccination coverage among populations of internally displaced persons (IDPs), refugees, and host communities in northern Iraq and the related underlying factors.Methods: Through a cross-sectional study conducted in five governorates in April–May 2022, 4,564 individuals were surveyed. Data were collected through an adapted questionnaire designed to gather data on participants.Results: 4,564 subjects were included (59.55% were 19–45 years old; 54.51% male). 50.48% of the participants (51.49% of host communities, 48.83% of IDPs, and 45.87% of refugees) had been vaccinated with at least one dose of COVID-19 vaccine. 40.84% of participants (42.28% of host communities, 35.75% of IDPs, and 36.14% of refugees) had been vaccinated by two doses, and 1.56% (1.65% of host communities, 0.93% of IDPs, and 1.46% of refugees) were vaccinated with three doses.Conclusion: Sociodemographic factors including age, gender, education, occupation, and nationality could affect vaccination coverage. Moreover, higher acceptance rate of vaccination is associated with belief in vaccine safety and effectiveness and trust in the ability of the vaccine to prevent complications

Construction and performance of a dilution-refrigerator based spectroscopic-imaging scanning tunneling microscope

We report on the set-up and performance of a dilution-refrigerator based spectroscopic imaging scanning tunneling microscope. It operates at temperatures below 10 mK and in magnetic fields up to 14T. The system allows for sample transfer and in situ cleavage. We present first-results demonstrating atomic resolution and the multi-gap structure of the superconducting gap of NbSe2 at base temperature. To determine the energy resolution of our system we have measured a normal metal/vacuum/superconductor tunneling junction consisting of an aluminum tip on a gold sample. Our system allows for continuous measurements at base temperature on time scales of up to ≈170 h.Publisher PDFPeer reviewe

Exploring bilingual EFL teacher resilience in the Iranian non-profit and state schools: a mixed-methods study

Abstract The present mixed-methods study investigated the factors that build Iranian bilingual Azeri-Persian English as a foreign language teacher resilience (TR) in non-profit and state schools. To do so, 205 male and female teachers selected through snowball sampling from several schools in different regions of Iran participated in this study. In the quantitative phase, the Connor and Davidson resilience scale (CD-RISC) was utilized to measure TR. First, the factor structure of the scale was ensured through testing confirmatory factor analysis (CFA). Results indicated that all the five factors of TR tested by the CD-RISC were evident among all the respondents, and there were no significant differences between the factors building TR in state and non-profit schools. For the qualitative phase, 26 male and female teachers selected through purposive sampling participated in semi-structured interviews which were thematically analyzed through MAXQDA software. The findings revealed that while state school teachers perceived satisfactory curriculum and policies and consulting with colleagues as the building factors for TR, non-profit school teachers highlighted teacher training courses, teacher-student rapport, and students’ progress as the important factors. The pedagogical implications of this study for teacher education are explained