EXTENDED-SPECTRUM BETA-LACTAMASE PRODUCING GRAM NEGATIVE BACTERIA IN IRAN

Background: The emergence and spread of extended spectrum β-lactamase (ESBL)-producing Gram- negative bacteria (GNB), particularly in Enterobacteriaceae, Acinetobacter baumannii, and Pseudomonas aeruginosa, have increased all over the world. ESBLs are characterized by their ability to hydrolyze β-lactams, early cephalosporins, oxyimino-thiazolyl cephalosporins, and monobactams, but not cephamycins or carbapenems. The rate of nosocomial infections caused by ESBL-producing GNB in Asia Pacific has increased and several studies have identified their prevalence in the region. The aim of this study is to review the prevalence of ESBL-producing GNB in the West Asia and the Middle East with a particular focus on Iran. Materials and Methods: The available evidence from various studies (Microbia and clinical studies, retrieved from the PubMed, and Scopus databases) regarding the ESBL producing Gram negative bacteria in Iran were evaluated. Results: In almost all parts of the country, high resistance has been observed, especially in the central part of Iran. Up to 89.8% Escherichia coli, 72.1% Klebsiella pneumonia, 84.2% Acinetobacter baumannii, and 83.8% Pseudomonas aeruginosa isolates are ESBL positive. Conclusion: The present study showed the increasing prevalence of ESBLs in different regions of Iran, which could be useful to strategic policy towards reducing reduce their prevalence

Functional Balance Tests for Patients with Multiple Sclerosis: A Review Study

Background: Knowledge of the functional balance tests for the patients with Multiple Sclerosis (PwMS) may provide useful and accurate information about the balance function of these patients under different situations. Objectives: This study aims to review the functional balance tests for PwMS. Materials and Methods: This is a systematic review. The search was conducted in PubMed, Scopus, LILACS, CINAHL, CENTRAL, Web of Science, PEDro, and Google Scholar databases on relevant studies published until November 2021. Results: Twenty-five articles and 25 different tests were found to evaluate the functional balance of PwMS. It was found that the studies used 6 tests to assess the static balance, 13 tests to assess dynamic balance, and 6 multi-item tests to assess functional balance in PwMS. Single-leg stance test, balance error scoring system test and steady stance test is a test battery for static balance; six-spot step test, timed up and go test, and figure-of-8 hop test are better for dynamic balance, and the balance evaluation systems test is a better multiitem test to assess the balance of PwMS by examining the postural control components. Conclusion: Single-limb standing test, balance error scoring system (BESS) test and steady stance test provide accurate data on static balance; six spot step test, Timed Get up and go test and figure-of-8 hop test provide valuable data on the dynamic balance and Balance Evaluation Systems Test (BESTest) is a valid test to assess the balance of PwMS from the perspective of the review of posture control components

Fabrication of Fullerene-Reinforced Aluminum Matrix Nanocomposites

Fullerene-reinforced Al matrix nanocomposites were fabricated by high-energy mechanical milling followed by consolidation through hot extrusion or high-pressure torsion (HPT). The results indicate that a relatively homogeneous microstructure consisting of elongated, micrometer-sized Al grains is formed in the hot-extruded specimens. However, the microstructure is not uniform along the radius of the HPT disks, which includes coarse grains near the center of the disk and ultrafine grains in the middle and along the edge of the specimen. Microstructural evaluations of the HPT disks indicate that Al grain refinement occurs due to the addition of fullerene, as grain size is reduced to 60 nm from 118 nm. The formation of the harmful aluminum carbide phase is not detected during the fabrication of Al/C-60 nanocomposites. The hardness, yield stress, and ultimate tensile strength of the Al-2 vol.% C-60 nanocomposites are about 27-160% higher than those of the monolithic Al samples, revealing the effective strengthening of fullerene particles in Al matrix. Moreover, mechanical properties of the Al/fullerene nanocomposites are significantly enhanced (59-272%) by utilizing HPT in comparison to hot-extruded specimens due to their much finer Al grain structure. The reduction in the number and the size of the dimples, as well as the formation of smooth regions on the tensile fracture surface of Al/C-60, results in their overall lower ductility compared to monolithic Al.11sciescopu

Significant Corrosion Resistance in an Ultrafine-Grained Al6063 Alloy with a Bimodal Grain-Size Distribution through a Self-Anodic Protection Mechanism

The bimodal microstructures of Al6063 consisting of 15, 30, and 45 vol. % coarse-grained (CG) bands within the ultrafine-grained (UFG) matrix were synthesized via blending of high-energy mechanically milled powders with unmilled powders followed by hot powder extrusion. The corrosion behavior of the bimodal specimens was assessed by means of polarization, steady-state cyclic polarization and impedance tests, whereas their microstructural features and corrosion products were examined using optical microscopy (OM), scanning transmission electron microscopy (STEM), field emission scanning electron microscopy (FE-SEM), electron backscattered diffraction (EBSD), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) techniques. The bimodal Al6063 containing 15 vol. % CG phase exhibits the highest corrosion resistance among the bimodal microstructures and even superior electrochemical behavior compared with the plain UFG and CG materials in the 3.5% NaCl solution. The enhanced corrosion resistance is attributed to the optimum cathode to anode surface area ratio that gives rise to the formation of an effective galvanic couple between CG areas and the UFG matrix. The operational galvanic coupling leads to the domination of a “self-anodic protection system” on bimodal microstructure and consequently forms a uniform thick protective passive layer over it. In contrast, the 45 vol. % CG bimodal specimen shows the least corrosion resistance due to the catastrophic galvanic corrosion in UFG regions. The observed results for UFG Al6063 suggest that metallurgical tailoring of the grain structure in terms of bimodal microstructures leads to simultaneous enhancement in the electrochemical behavior and mechanical properties of passivable alloys that are usually inversely correlated. The mechanism of self-anodic protection for passivable metals with bimodal microstructures is discussed here for the first time

One-pot synthesis of tin chalcogenide-reduced graphene oxide-carbon nanotube nanocomposite as anode material for lithium-ion batteries

In this study, a ternary tin chalcogenide (TC)–reduced graphene oxide (RGO)–carbon nanotube (CNT) nanocomposite was synthesized as a lithium-ion battery (LIB) anode by a simple one-step protocol. The nanocomposite was prepared through a hydrothermal method using tin chloride as the tin precursor, thiourea as the sulfur source and reducing agent, and GO–CNT hybrid as the carbonaceous nanostructure. The structure, morphology, and phase analysis of the synthesized nanocomposite powder were investigated using Raman spectroscopy, field-emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD). The results show that GO is reduced while SnS and SnS2 nanosheets along with SnO2 nanoparticles are simultaneously formed within the RGO–CNT hybrid framework throughout the hydrothermal process. During the first lithiation–delithiation process, the discharge capacity and the columbic efficiency for the ternary TC–RGO–CNT nanocomposite electrode at a current density of 50 mA g−1 are 1401 mA h g−1 and 50%, respectively. The TC–RGO–CNT electrode gives an improved capacity of 197 mA h g−1 at 500 mA g−1 while the corresponding value for the bare TC, and binary TC–CNT and TC–RGO nanocomposite electrodes was only 5, 18, and 41 mA h g−1, respectively. Meanwhile, the ternary nanocomposite anode indicates outstanding stability after 150 cycles with a reversible capacity of 100 mA h g−1 at 500 mA g−1. The excellent electrochemical performance of the ternary TC–RGO–CNT nanocomposite is ascribed to the synergistic effect of the high capacity of electrochemically-active TC nanostructures along with the large surface area, porous structure, and exceptional conductivity of the 3D RGO–CNT framework

The effect of graphene-based nanofillers on the structure, thermal, and mechanical properties of poly(vinyl alcohol)

PVA matrix composite films reinforced with graphene oxide (GO) and reduced graphene oxide (rGO) nanoplatelets are prepared by water-solution processing. The structure and properties of the composites are investigated by field-emission scanning electron microscopy, Raman spectroscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, and dynamic mechanical analysis. The results indicate a 22% improvement in the storage modulus and a 12°C increase in the glass transition temperature by the addition of only 0.5 wt% rGO into the PVA. The enhancement of the mechanical and thermal properties of the composite films is attributed to the hydrogen bond barrier and molecule movement restriction effects. The higher amount of the hydrogen bonds in the PVA/rGO composite compared to the PVA/GO sample cause its higher thermal stability and mechanical performance

Aflatoxin determination in saffron by high-performance liquid chromatography and immunoaffinity column clean-up

In this paper, method based on high performance liquid chromatography with fluorescence detection has been suggested to measure aflatoxin in saffron. This method required a simple extraction of aflatoxin using MeOH/H2O (80:20, v/v) and a purification by immunoaffinity column cleanup. Aflatoxin measurement was performed at an emission wavelength of 445 nm and an excitation wavelength of 365 nm. Detection limits for AFB1, AFB2, AFG1 and AFG2 were 0.293, 0.08, 0.55, and 0.30 ng g-1, respectively. The percentage of Relative standard deviations for measuring aflatoxin is in the range of 1.33-5.10 % and the percentage of recovery is in the range of 94-67. Regarding The overall results of high-performance liquid chromatography applied in this experiment, we can realize that this method can be used for detection and measurement of different kinds of aflatoxins in saffron