Non-linear response to electric field in extended Hubbard models

The electric-field response of a one-dimensional ring of interacting fermions, where the interactions are described by the extended Hubbard model, is investigated. By using an accurate real-time propagation scheme based on the Chebyshev expansion of the evolution operator, we uncover various non-linear regimes for a range of interaction parameters that allows modeling of metallic and insulating (either charge density wave or spin density wave insulators) rings. The metallic regime appears at the phase boundary between the two insulating phases and provides the opportunity to describe either weakly or strongly correlated metals. We find that the {\it fidelity susceptibility} of the ground state as a function of magnetic flux piercing the ring provides a very good measure of the short-time response. Even completely different interacting regimes behave in a similar manner at short time-scales as long as the fidelity susceptibility is the same. Depending on the strength of the electric field we find various types of responses: persistent currents in the insulating regime, dissipative regime or damped Bloch-like oscillations with varying frequencies or even irregular in nature. Furthermore, we also consider the dimerization of the ring and describe the response of a correlated band insulator. In this case the distribution of the energy levels is more clustered and the Bloch-like oscillations become even more irregular

Field effect on surface states in a doped Mott-Insulator thin film

Surface effects of a doped thin film made of a strongly correlated material are investigated both in the absence and presence of a perpendicular electric field. We use an inhomogeneous Gutzwiller approximation for a single band Hubbard model in order to describe correlation effects. For low doping, the bulk value of the quasiparticle weight is recovered exponentially deep into the slab, but with increasing doping, additional Friedel oscillations appear near the surface. We show that the inverse correlation length has a power-law dependence on the doping level. In the presence of an electrical field, considerable changes in the quasiparticle weight can be realized throughout the system. We observe a large difference (as large as five orders of magnitude) in the quasiparticle weight near the opposite sides of the slab. This effect can be significant in switching devices that use the surface states for transport

Job Stress and Work Ability Among Emergency Nurses in Isfahan, Iran

Background: Job stress is one of the most common health problems with clinical and psychological consequences, which can affect work ability among emergency nurses. Nevertheless, more studies are needed to shed light on the status of this disorder and its relevance to work ability in nurses in the emergency departments (EDs). Objectives: The current study aimed to determine job stress among emergency nurses and its association with work ability. Methods: This cross-sectional study was conducted in 2013 in hospitals affiliated to Isfahan University of Medical Sciences, Isfahan, Iran. Two hundred nurses who worked in the EDs were asked to complete a demographic questionnaire and special scales to assess their job stress and work ability. T-tests, analysis of variance, Pearson correlation coefficient and linear regression were used to analyze the data. Results: The mean job stress and work ability scores were 151.09 ± 0.01 and 26.9 ± 8.2, respectively. Fifty-five percent of the subjects had high job stress and fifty-seven percent showed low work ability. A significant indirect correlation was found between job stress and work ability scores in the subjects (P = 0.015). Conclusions: Nurses working in the EDs experience a high level of job stress and low work ability. This may decrease the quality of care and patients’ safety. Fulfilling the staff shortage in ED and improving management behaviors are important in this regard

Systematic selection of small molecules to promote differentiation of embryonic stem cells and experimental validation for generating cardiomyocytes.

Small molecules are being increasingly used for inducing the targeted differentiation of stem cells to different cell types. However, until now no systematic method for selecting suitable small molecules for this purpose has been presented. In this work, we propose an integrated and general bioinformatics- and cheminformatics-based approach for selecting small molecules which direct cellular differentiation in the desired way. The approach was successfully experimentally validated for differentiating stem cells into cardiomyocytes. All predicted compounds enhanced expression of cardiac progenitor (Gata4, Nkx2-5 and Mef2c) and mature cardiac markers (Actc1, myh6) significantly during and post-cardiac progenitor formation. The best-performing compound, Famotidine, increased the percentage of Myh6-positive cells from 33 to 56%, and enhanced the expression of Nkx2.5 and Tnnt2 cardiac progenitor and cardiac markers in protein level. The approach employed in the study is applicable to all other stem cell differentiation settings where gene expression data are available.YK and AB thank the European Research Council (ERC Starting Grant 2013 to AB) for funding.This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/cddiscovery.2016.

N-acetylcysteine compared to metformin, improves the expression profile of growth differentiation factor-9 and receptor tyrosine kinase c-kit in the oocytes of patients with polycystic ovarian syndrome

Background: Paracrine disruption of growth factors in women with polycystic ovarian syndrome (PCOS) results in production of low quality oocyte, especially following ovulation induction. The aim of this study was to investigate the effects of metformin (MET), N-acetylcysteine (NAC) and their combination on the hormonal levels and expression profile of GDF-9, BMP-15 and c-kit, as hallmarks of oocyte quality, in PCOS patients. Materials and Methods: This prospective randomized, double-blind, placebo controlled trial aims to study the effects of MET, NAC and their combination (MET+NAC) on expression of GDF-9, BMP-15 and c-kit mRNA in oocytes [10 at the germinal vesicle (GV) stage, 10 at the MI stage, and 10 at the MII stage from per group] derived following ovulation induction in PCOS. Treatment was carried out for six weeks, starting on the third day of previous cycle until oocyte aspiration. The expression of GDF9, BMP15 and c-kit were determined by quantitative real time polymerase chain reaction (RT-qPCR) and western blot analysis. Data were analyzed with one-way ANOVA. Results: The follicular fluid (FF) level of c-kit protein significantly decreased in the NAC group compared to the other groups. Significant correlations were observed between the FF soluble c-kit protein with FF volume, androstenedione and estradiol. The GDF-9 expression in unfertilized mature oocytes were significantly higher in the NAC group compared to the other groups (P<0.001). Similar difference was not observed between the MET, NAC+MET and control groups. The c-kit expression in unfertilized mature oocytes were significantly lower in the NAC group compared to the other groups (P<0.001). Similar difference was not observed between the MET, NAC+MET and control groups (Registration number: IRCT201204159476N1). Conclusion: We concluded that NAC can improve the quality of oocytes in PCOS. © 2017, Royan Institute (ACECR). All rights reserved

A Novel Integration of CWPO Process with Fe3O4@C and Sonication for Oxidative Degradation of 4-Chlorophenol

This current work deals with oxidative destruction of 4-chlorophenol (4-CP) with catalytic wet peroxide oxidation (CWPO) using Fe3O4@C and sonication (US) in aqueous solution. The Fe3O4@C catalyst was synthetized and characterized with Field Emission Electron Microscopy and X-Ray Diffraction. Effect of operational variables, including initial pH, catalyst dosage, H2O2 concentration, 4-CP concentration, and sonication were investigated. A removal efficiency of 99 % was obtained by the CWPO/US-Fe3O4@C process in selected conditions including pH 5, Fe3O4@C dosage of 0.8 g L–1, H2O2 concentration of 20 mM, sonication power of 300 W, and reaction time of 60 min. Results indicated significant 4-CP removal with CWPO/US-Fe3O4@C (99 %) compared to CWPO (67 %) and US (10 %). According to the results, Fe3O4@C nanocomposite can be considered a cost-effective catalyst since it demonstrated acceptable reusability performance in degradation of 4-CP by CWPO/US-Fe3O4@C process. This work is licensed under a Creative Commons Attribution 4.0 International License

Reduction of truncated Kit Expression in Men with Abnormal Semen Parameters, Globozoospermia and History of Low or Fertilization Failure

Objective: Phospholipase C zeta 1 (PLCζ) is one of the main sperm factor involved in oocyte activation and other factors may assist this factor to induce successful fertilization. Microinjection of recombinant tr-kit, a truncated form of c-kit receptor, into metaphase II-arrested mouse oocytes initiate egg activation. Considering the potential roles of tr-KIT during spermiogenesis and fertilization, we aimed to assess expression of tr-KIT in sperm of men with normal and abnormal parameters and also in infertile men with previous failed fertilization and globozoospermia. Materials and Methods: This experimental study was conducted from September 2015 to July 2016 on 30 normozoospermic and 20 abnormozoospermic samples for experiment one, and also was carried out on 10 globozoospermic men, 10 men with a history low or failed fertilization and 13 fertile men for experiment two. Semen parameters and sperm DNA fragmentation were assessed according to WHO protocol, and TUNEL assay. Sperm tr-KIT was evaluated by flow cytometry, immunostaining and western blot. Results: The results show that tr-KIT mainly was detected in post-acrosomal, equatorial and tail regions. Percentage of tr-KIT-positive spermatozoa in abnormozoospermic men was significantly lower than normozoospermic men. Also significant correlations were observed between sperm tr-KIT with sperm count (r=0.8, P<0.001), motility (r=0.31, P=0.03) and abnormal morphology (r=-0.6, P<0.001). Expression of tr-KIT protein was significantly lower in infertile men with low/ failed fertilization and globozoospermia compared to fertile men. The significant correlation was also observed between tr-KIT protein with fertilization rate (r=-0.46, P=0.04). In addition, significant correlations were observed between sperm DNA fragmentation with fertilization rate (r=-0.56, P=0.019) and tr-KIT protein (r=-0.38, P=0.04). Conclusion: tr-KIT may play a direct or indirect role in fertilization. Therefore, to increase our insight regarding the role of tr-KIT in fertilization further research is warranted. © 2019 Royan Institute (ACECR). All rights reserved