Highly efficient helium purification through a dual-membrane system: insights from molecular dynamics simulations.

Almost all helium is resourced from natural gas reservoirs. Hence, it is essential to develop new efficient technologies to recover helium from natural gas. In this work, we propose a novel dual membrane system, consisting of C2N (M1) and graphdiyne (M2) membranes, to separate and purify helium from a ternary gas mixture of He/N2/CH4. In this regard, we performed molecular dynamics (MD) simulations to investigate the separation performance of the proposed system. Here, we explored the effect of applied pressure (up to 2 MPa) and the feed composition on the separation performance. The simulation results revealed that in the designed system, the M1 membrane allows He and N2 to diffuse through and prevents CH4 from crossing even at an applied pressure gradient. Next, the M2 membrane only allows He to transfer through and prevents N2 from crossing even at the applied pressure gradient. As a result, the dual membrane system showed a high He permeance of 2.5 × 106 GPU and ultrahigh He selectivity. In addition, the suggested dual membrane system could separate three components simultaneously at the applied pressure of 2 MPa, which implies the outstanding performance of the system. We also analyzed the density map, the van der Waals interactions, and the potential of the mean force calculations to better understand the permeation of gas species across the designed system.

Sensitive and selective electrochemical detection of bisphenol A based on SBA-15 like Cu-PMO modified glassy carbon electrode.

This work reports the electrochemical detection of bisphenol A (BPA) using a novel and sensitive electrochemical sensor based on the Cu functionalized SBA-15 like periodic mesoporous organosilica-ionic liquid composite modified glassy carbon electrode (Cu@TU-PMO/IL/GCE). The structural morphology of Cu@TU-PMO is characterized by X-ray powder diffraction (XRD), energy dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), Field emission scanning electron microscopy (FE-SEM), and Brunauer-Emmett-Teller (BET). The catalytic activity of the modified electrode toward oxidation of BPA was interrogated with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in phosphate buffer solution (pH 7.0) using the fabricated sensor. The electrochemical detection of the analyte was carried out at a neutral pH and the scan rate studies revealed that the sensor was stable. Under the optimal conditions, a linear range from 5.0 nM to 2.0 µM and 4.0 to 500 µM for detecting BPA was observed with a detection limit of 1.5 nM (S/N = 3). The sensor was applied to detect BPA in tap and seawater samples, and the accuracy of the results was validated by high-performance liquid chromatography (HPLC). The proposed method provides a powerful tool for the rapid and sensitive detection of BPA in environmental samples.

Biosynthesis of AgNPs onto the urea-based periodic mesoporous organosilica (AgxNPs/Ur-PMO) for antibacterial and cell viability assay.

Nano-size silver particles were stabilized on the inner surfaces of urea based periodic mesoporous organosilica (Ur-PMO). Aqueous extract of Euphorbia leaves as a sustainable and green reducing agent was applied for Ag-nanoparticles growth into the Ur-PMO channels. Physical and chemical properties of organosilica materials synthesized using various techniques such as FT-IR, small-angle XRD, PXRD, FESEM, TEM, SEM-EDX and atomic absorption spectrometry (AAS) were examined. Finally, the AgNPs/Ur-PMO were investigated on cell viability assay. An in vitro cytotoxicity test using MMT assay displayed that the designed material has good biocompatibility and could be a promising candidate for biomedical applications. The results also showed that the AgNPs/Ur-PMO compounds (especially, PMO; 1.27% AgNPs) had relatively good antibacterial and antibiofilm effects. It seems that the use of these compounds in hospital environments can reduce nosocomial infections as well as reduce antibiotic-resistant bacteria.

Psp140: an immunodominant antigen in the supernatant of Streptococcus pneumoniae culture.

BACKGROUND AND OBJECTIVES: Streptococcus pneumoniae causes many lethal infections. Due to its reduced sensitivity to commonly used antibiotics, development of new strategies against pneumococcal infections seems to be necessary. We aimed to investigate immunodominant antigens in S. pneumoniae culture supernatant in order to develop novel targets for pneumococcal vaccines. MATERIALS AND METHODS: In this study S. pneumoniae ATCC49619 was sub-cultured into BHI broth from overnight culture at 37°C for 4 h. The supernatant proteins were precipitated using acetone precipitation method. A rabbit was intramuscularly immunized with alum adjuvant and 100 µg pneumococcal supernatant proteins, 6 times at 14 days' intervals to produce hyperimmune serum. ELISA assay was performed to determine the antibody level response to pneumococcal secretory proteins. Then dot blot applied for rapid evaluation of hyperimmune serum reactivity to pneumococcus supernatant proteins. The western blot was also used to determine the interaction of supernatant proteins with immunogenic rabbit's hyperimmune-serum. RESULTS: According to the western blot analysis, the immunodominant protein had 140KDa molecular weight and designated as pneumococcal secretory protein140 (Psp140). CONCLUSION: The Psp140 protein in the supernatant of S. pneumoniae culture is an immunodominant protein and it is likely related to pneumococcal secretory protein or surface exposed protein which released into culture supernatant during bacterial growth.

Monitoring of drug resistance towards reducing the toxicity of pharmaceutical compounds: Past, present and future.

Drug resistance is worldwide health care crisis which decrease drug efficacy and developing toxicities. Effective resistance detection techniques could alleviate treatment cost and mortality associated with this crisis. In this review, the conventional and modern analysis methods for monitoring of drug resistance are presented. Also, various types of emerging rapid and sensitive techniques including electrochemical, electrical, optical and nano-based methods for the screening of drug resistance were discussed. Applications of various methods for the sensitive and rapid detection of drug resistance are investigated. The review outlines existing key issues in the determination which must be overcome before any of these techniques becomes a feasible method for the rapid detection of drug resistance. In this review, the roles of nanomaterials on development of novel methods for the monitoring of drug resistance were presented. Also, limitations and challenges of conventional and modern methods were discussed.

Experimental and numerical assessment of saltwater recession in coastal aquifers by constructing check dams.

Artificial freshwater recharge has been considered as a feasible and effective procedure to mitigate seawater intrusion in coastal regions. The efficiency of freshwater infiltration through a check dam reservoir on saltwater recession (SWR) is investigated using two physical models. The results demonstrate the apparent tendency of recharge freshwater to move horizontally toward the boundaries rather than flowing downward to influence saltwater wedge toe. Thereby, it would affect the saltwater wedge tip instead of its toe due to the new establishment of a positive hydraulic gradient from a dam reservoir to the boundaries. Moreover, numerical dispersive simulations have been carried out on a large-scale aquifer to find the optimum location of the dam as well as the aquifer characteristics impacts on SWR efficiency. The results show that the best location to construct a check dam is immediately above the saltwater wedge toe. It is found that when saltwater head declines, the steeper hydraulic gradient between boundaries is established and the efficiency of recharge performance will be improved. Moreover, the reduction of hydraulic conductivity in vertical direction improves SWR, while higher hydraulic conductivity in the homogeneous cases only accelerates the infiltration rate but has no meaningful effect in the long term. The considered recharge method also works better in scenarios with higher dispersivity. However, the construction of check dams on floodways might be a practical and low-cost solution but it can be concluded that as the dominant direction of the recharged freshwater is toward boundaries, it cannot promptly retreat saltwater around toe position.

Formation and stabilization of colloidal ultra-small palladium nanoparticles on diamine-modified Cr-MIL-101: Synergic boost to hydrogen production from formic acid.

Ultra-small nano-sized palladium particles were successfully stabilized within the pores of diamine groups grafted open metal site metal-organic frameworks of Cr-MIL-101; coordinated diamine groups of ethylene diamine (ED) and propyl diamine (PD) on the active site of chromium units of Cr-MIL-101. The physiochemical properties of the Pd@Cr-MOFs were investigated using FTIR, XRD, SEM/EDX mapping, TEM, BET, and AAS. The Cr-MIL-101 stabilized ultra-small Pd nanoparticles, Pd@(ethylene diamine)/Cr-MIL-101, and Pd@(propyl diamine)/Cr-MIL-101, displayed catalytic activity for clean dehydrogenation of formic acid and generation of hydrogen at room temperature. The resultant Pd@ED/Cr-MIL-101 catalyst indicates high catalytic activity with turnover frequency (TOF) of 583 h-1 at 328 K, which is superior to most of the reported catalysts, including Pd@PD/Cr-MIL-101 with TOF 532 h-1. Our studies open up a new method to the design of an ultra-small metal nanoparticle for the catalytic dehydrogenation of HCOOH.

The Potential Applications of Hyaluronic Acid Hydrogels in Biomedicine.

Hyaluronic acid (HA) is widely used in the biomedicine due to its biocompatibility, biodegradability, and nontoxic properties. It is crucial for cell signaling role during morphogenesis, inflammation, and wound repair. After hydrogel formation, HA easily is converted to elastic sheets in order to use in preclinical and clinical applications. In addition, HA-derived hydrogels are easily used as vectors for cell and medication in tissue repairing and regenerative medicine. Moreover, in comparison with other polymers, HA -based hydrogels play a key role in in cellular behavior, including stem cell differentiation. The current paper reviews both basic concepts and recent advances in the development of HA-based hydrogels for biomedical applications.

Hepatoprotective role of berberine against paraquat-induced liver toxicity in rat.

Paraquat (PQ) is a herbicide agent commonly used in agricultural applications. Hepatotoxicity is among clinical complications associated with PQ intoxication. Oxidative stress and its subsequent events are major mechanisms identified in PQ-induced liver toxicity. Berberine (BBR) is a natural antioxidant widely investigated for its hepatoprotective effects. The present study designed to evaluate the potential cytoprotective properties of BBR against PQ-induced cytotoxicity in primary cultured rat hepatocytes and in vivo test of liver function enzymes. Cellular and biochemical parameters including lactate dehydrogenase (LDH), cell viability, ROS formation, glutathione (GSH) content, and mitochondrial membrane potential in the PQ-treated hepatocytes were measured, and the mentioned markers were evaluated in the presence of BBR. BBR treatment caused significant decrease in PQ-induced cell death, ROS formation, and LDH release. On the other hand, it was found that BBR inhibits cellular glutathione depletion in PQ-treated hepatocytes. Also, BBR treatment significantly diminished PQ-induced the liver function enzyme elevation. These data mention the potential hepatoprotective effect of BBR with therapeutic capability against PQ-induced liver damage.

Prevalence of extended-spectrum beta-lactamase genes in Acinetobacter baumannii strains isolated from nosocomial infections in Tehran, Iran.

Background and objectives: bla SHV, bla TEM and bla VEB are a group of Extended-Spectrum Beta-Lactamase enzymes (ESBLs) which are able to hydrolyze Penicillins and some cephalosporin antibiotics. The present study evaluated the frequency of ESBL genes bla SHV, bla TEM and bla VEB in Acinetobacter baumannii strains isolated from nosocomial infections to outline the importance of these genes in antibiotic resistance. Methods: One hundred Acinetobacter baumannii strains were isolated from different nosocomial infections. After antibiotic resistance evaluation with the Kirby-Bauer disc-diffusion method, the Minimum Inhibitory Concentration (MIC) of Ciprofloxacin was measured using the E-test method. Then, the ESBL producing strains were identified employing Combined Disk Methods. Finally, all isolates were evaluated with the Polymerase Chain Reaction (PCR) technique to detect the ESBL genes of interest. Results: Out of 100 Acinetobacter baumannii isolates, 59% were ESBL positive according to the phenotypic method. The PCR assay could not detect the bla SHV and bla VEB genes in the studied isolates, but the presence of bla TEM gene was demonstrated in 42% of the strains. Conclusion: The high resistance to most antibiotics, the high prevalence of ESBLs-producing strains and also a high prevalence of bla TEM gene in A. baumannii strains found in the current study gives cause for major concern about nosocomial infections in Iran because of the treatment complexity of these strains. Our results highlight the need for infection control measures to prevent the spread of resistant isolates, especially in hospitals.

Clinical and Bacterial Risk Factors for Development of Post-Prostate Biopsy Infections.

PURPOSE: To research on clinical and bacterial risk factors and their relationship with post-prostate biopsy infection (PBI). MATERIALS AND METHODS: In this prospective cohort study, rectal swabs were collected from 158 men prior to prostate biopsy and cultured selectively for identify ciprofloxacin-resistant (FQ-R) gram-negative bacteria. The patient characteristics, phylogenetic background, sequence typing and pulsed field gel electrophoresis (PFGE) pattern were compared in two groups of FQ-R E. coli rectal and clinical isolates. RESULTS: In total, PBI was observed in 20 (12.5%) cases; the most of these subjects were FQ-R-colonized. (17/73 [24%] vs 3/85 [3.5%]; P < 0.001). FQ-R colonization, diabetes, hospitalization and UTI were independent risk factors (95% CI: 1.1-20.1, OR = 4.73; 95% CI: 1.7-25.3, OR = 6.57; 95% CI: 1.9-27.5, OR = 7.22; and 95% CI: 1.2-14.3, OR = 4.05; respectively),  that increased the rate of PBI (All P < 0.05). Despite the increase in infections among patients colonized with strains of E. coli ST131, its prevalence was near significance between colonized and infected groups (P = 0.07). The PFGE patterns and antimicrobial susceptibility profiles of rectal and clinical isolates in 13 patients were similar which is remarkably important and informative. CONCLUSIONS: The most PBIs originate from FQ-R E. coli rectal colonization. Rectal culture screening and assessment of clinical risk factors can predict the incidence of PBI in patients.

Effect of silver nanoparticles in the induction of apoptosis on human hepatocellular carcinoma (HepG2) cell line.

Silver nanoparticles (Ag NPs) serve numerous chief functions in cosmetics, engineering, textile, food technology and medicine. These nanoparticles are also utilized in the pharmaceutical industry particularly in the production of novel antimicrobial agents. However, despite the various studies of Ag NPs induced toxicity, there is a lack of information concerning cellular toxicity mechanisms of these nanoparticles on human cells. In the current project, we investigate the anti-cancer effects of Ag NPs in HepG2 (liver hepatocellular adenocarcinoma) cells. The mean particle size and morphology for the prepared nanoparticles were determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. Cell viability, reactive oxygen species (ROS) formation, cytochrome c amount and expression level of BAX/CASP 3/CASP 8/CASP 9 were assayed in HepG2 cells after incubation with Ag NPs. The prepared nanoparticles showed the mean particle size of 30.71 nm with polydispersity index (PDI) of 0.21. Our results revealed decreased cell viability in a concentration-dependent manner and the IC50 of 75 µg/mL for Ag NPs. Ag NPs cytotoxicity was associated with induction of ROS and cell apoptosis in HepG2 cell line. According to our findings, Ag NPs could be considered as potential chemotherapeutic agents in the treatment of liver hepatocellular carcinoma.

Metabolic syndrome and its components in premenopausal and postmenopausal women: a comprehensive systematic review and meta-analysis on observational studies.

OBJECTIVES: To perform a meta-analysis on the global prevalence of metabolic syndrome (MetS) in postmenopausal women. The meta-analysis also sought to measure the relationship menopause status has with MetS and its components. METHODS: The Web of Science, Medline, PubMed, Scopus, Embase, CINAHL, DOAJ, and Google Scholar were all searched using the relevant keywords. Articles published during the period 2004 to 2017 that met our inclusion criteria and reported the prevalence of MetS among premenopausal and postmenopausal women were included. In the presence of heterogeneity, random-effects models were used to pool the prevalence and odds ratios (ORs), as measures of association in cross-sectional and comparative cross-sectional studies, respectively. RESULTS: The prevalence of MetS among postmenopausal women (119 studies [n = 95,115]) and the OR comparing the prevalence of MetS among postmenopausal and premenopausal women (23 studies [n = 66,801]) were pooled separately. The pooled prevalence of MetS among postmenopausal women was found to be 37.17% (95% confidence interval [CI] 35.00%-39.31%), but varied from 13.60% (95% CI 13.55%-13.64%) to 46.00% (95% CI 1.90%-90.09%), depending upon the diagnostic criteria used. The overall pooled OR for MetS in postmenopausal women, compared with premenopausal women, was OR 3.54 (95% CI 2.92-4.30), but this ranged from OR 2.74 (95% CI 1.32-5.66) to OR 5.03 (95% CI 2.25-11.22), depending upon the criteria used. Furthermore, the odds of high fasting blood sugar (OR 3.51, 95% CI 2.11-5.83), low high-density lipoprotein cholesterol (OR 1.45, 95% CI 1.03-2.03), high blood pressure (OR 3.95, 95% CI 2.01-7.78), high triglycerides (OR 3.2, 95% CI 2.37-4.31), and high waist circumference (OR 2.75, 95% CI 1.80-4.21) were all found to be higher in postmenopausal women than in premenopausal women. CONCLUSIONS: The prevalence of MetS is relatively high in postmenopausal women and was more prevalent among postmenopausal than premenopausal women. Menopausal hormone therapy should be used with caution in patients with MetS, as its safety has not yet been evaluated among MetS patients and meticulous evaluation of each individual patient before starting MHT is needed.

The promising future of nano-antioxidant therapy against environmental pollutants induced-toxicities.

Developmental toxicity caused by exposure to a mixture of environmental pollutants has become a major health concern. Human-made chemicals, including xenoestrogens, pesticides, heavy metals, polycyclic aromatic hydrocarbons (PAHs) are major factors that increase formation of Reactive Oxygen Species (ROS) and adversely influence endogen antioxidant defense. Humans have evolved complex antioxidants systems that protect cells from prooxidant conditions. Deficiency of any these components can cause destruction in the overall antioxidant status of an individual. Antioxidants agents can be endogenous or obtained exogenously, as a part of a diet or through dietary supplements. Although oxidative damage contributes to many pathologies the use of naturally occurring, small-molecule exogenous antioxidants as therapies for these disorders has not been successful. An ideal exogenous antioxidant should be readily absorbed, enough delivered to intracellular location required to decrease pathological oxidative damage, positively affecting gene expression. To develop effective antioxidant therapies the best strategy may be to create new nanoscale drug delivery systems. This review highlights the role of environmental induced oxidative stress factors and novel nanoparticle design techniques of antioxidants.

Prevalence and significance of fluoroquinolone-resistant bacteria carriage in patients undergoing transrectal ultrasound prostate biopsy.

PURPOSE: To determine the prevalence of fluoroquinolone-resistant (FQR) bacteria carriage in patients undergoing transrectal ultrasound prostate biopsy (TRUS-Bx), and the relationship between the risk factors and FQR carriers as well as infections after prostate biopsy. MATERIALS AND METHODS: Rectal swabs were obtained from 158 patients undergoing TRUS-Bx. The FQR organisms were isolated using selective media, and the antibiotic susceptibility pattern was determined. Moreover, after prostate biopsy, blood and urine samples were collected from patients with post-biopsy infection (PBI) during 30days of follow up. RESULTS: In total, 73 (46.2%) patients were positive for ciprofloxacin-resistant bacteria in rectal cultures. The most dominant isolates were Escherichia coli (95.9%). The antibiotic susceptibility patterns for the FQR rectal and clinical isolates showed high levels of resistance to ampicillin (94%) and trimethoprim-sulfamethoxazole (89.5%), while the resistance to amikacin, fosfomycin and imipenem remained very low. The multivariate analysis showed that previous use of FQs (OR, 2.54; 95% CI, 1.17-5.49; P = .019) and history of hospitalization (OR, 7.85; 95% CI, 2.075-29.744; P = .002) were significantly risk factors for the FQR carriage. On the other hand, the risk of PBI was higher among intestinal carriers of fluoroquinolone resistant bacteria compared with noncarriers, that this difference was statistically significant (24% versus 3.5%, P < .001).The rates of PBI and hospitalization after TRUS-Bx were 12.5%, and 4.43%, respectively. CONCLUSION: An increase in the rectal FQR bacteria carriage is associated with elevated PBI, which strongly recommendsthe need for an appropriate prophylaxis to reduce infections in patients undergoing TRUS-Bx.