Different ligand based monodispersed Pt nanoparticles decorated with rGO as highly active and reusable catalysts for the methanol oxidation

Addressed herein, a highly effective and monodisperse Pt/L@rGO nanocatalysts were successfully synthesized by using different types of ligands (pentylamine, Pt/PA@rGO and tripentylamine, Pt/TPA@rGO) and the impact of ligand on catalytic activity of the prepared nanomaterials have been examined for methanol oxidation. An easy and facile ultrasonication method was applied to produce highly efficient, monodispersed and durable (Pt) NPs dispersed on reduced graphene oxides (rGO). The structure morphology, composition and properties of Pt/L@rGO NPs were characterized by using different techniques such as ICP-OES, XPS, TEM, HRTEM, and XRD methods. A different ligand based monodisperse Pt (0) nanocatalysts have been compared with each other and commercial catalysts in terms of catalytic performance, life-time and reusability of catalyst for methanol oxidation reaction in THF at room temperature. All experimental results demonstrate the highly stable and reusable rGO furnished Pt (0) nanomaterials and their excellent catalytic performance in the methanol oxidation reactions at room temperature.     

Molecular methods for identification of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus using methionine biosynthesis and 16S rRNA genes

Yoghurt and starter culture producers are still searching strains of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus to produce healthier yogurt with longer shelf life, better texture, taste and quality. However, selective identification of Lb. delbrueckii subsp. bulgaricus and Strep. thermophilus from a mixed population using microbiological and biochemical methods is difficult, time consuming and may not be accurate. In this study, a quick, sensitive and accurate method is proposed to identify both Lb. delbrueckii subsp. bulgaricus and Strep. thermophilus using PCR. The method is comprised of two parts. In the first part, methionine biosynthesis genes, known to be present in both species were partially amplified by designed primers (cysmet2F and cysmet2R). Partial amplification of the methionine biosynthesis gene which gives 700 bp fragment resulted in selective identification of Lb. bulgaricus and Strep. thermophilus. All 16 Lb. bulgaricus and 6 Strep. thermophilus isolates assessed by this method gave the expected amplification. On the other hand, further analysis of other closely related species with the same primers have indicated that the same product was also amplified in two more lactobacilli namely, Lb. delbrueckii subsp. lactis and Lb. helveticus species. Thus, in the second part of the method, further differentiation of Lb. delbrueckii subsp. bulgaricus and Strep. thermophilus from each other and these species was achieved using restriction analysis of 16S rRNA gene with EcoRI.     

Particle-phase dry deposition and air-soil gas exchange of polycyclic aromatic hydrocarbons (PAHs) in Izmir, Turkey

Ambient air and dry deposition samples were collected at suburban and urban sites in Izmir, Turkey. Atmospheric total (particle+gas) ∑(14)PAHs concentrations were 36±39 and 144±163 ng m(-3) for suburban and urban sites, respectively. Phenanthrene was the most abundant compound at all sites, and all samples were dominated by low molecular weight PAHs. Average particulate ∑(14)PAH dry deposition fluxes were 8160±5024 and 4286±2782 ng m(-2) day(-1) and overall average particulate dry deposition velocities were 1.5±2.4 and 1.0±2.3 cm s(-1) for suburban and urban sites, respectively. Soil samples were collected at suburban site. Average soil concentration for ∑(14)PAH was 55.9±14.4 ng g(-1) dry weight. Calculated gas-phase air-soil exchange fluxes indicated that fluorene, phenanthrene, anthracene, and carbazole were deposited to soil in winter while they were volatilized in summer. Other compounds (fluoranthene-benzo[g,h,i]perylene) were deposited to soil in both periods. Annual average fluxes of PAHs representing soil to air (i.e., gas volatilization) and air to soil transfer (i.e., gas absorption, dry deposition, and wet deposition) processes were also compared. All processes were comparable for Σ(14)PAHs however their input was dominated by gas absorption. Gas absorption dominated for lower molecular weight PAHs, however dry deposition dominated for higher molecular weight PAHs. The results have suggested that for fluorene, soil and air may be approaching a steady state condition. For the remaining compounds, there was a net accumulation into the soil.     

Characterization of Sultaniye grape (Vitis vinifera L. cv. Sultana) polyphenol oxidase

Polyphenol oxidase (PPO) was extracted from Sultaniye grapes grown in Turkey, and its characteristics in terms of pH and temperature optima, thermal inactivation, kinetic parameters and potency of some PPO inhibitors were studied. Optimum pH and temperature for grape PPO were found to be 3.4 and 30 °C, using catechol as substrate. K_m and V_max values were found to be 44.5 ± 5.47 mm and 0.695 ± 0.0353 OD₄₁₀ min^?1, respectively. Four inhibitors were tested in this study and the most potent inhibitor was sodium metabisulphite, followed by ascorbic acid. From the thermal inactivation studies in the range of 65–80 °C, the half‐life values of the enzyme ranged between 2.6 and 49.5 min. Activation energy (E_a) and Z values were calculated to be 208.5 kJ mol^?1 (r² = 0.9544) and 10.95 °C (r² = 0.9517), respectively.     

HFE gene mutation is a risk factor for tissue iron accumulation in hemodialysis patients

Introduction: HFE gene mutations are responsible from iron overload in general population. Studies in hemodialysis patients investigated the effect of presence of HFE gene mutations on serum ferritin and transferrin saturation (TSAT) with conflicting results. However effect of HFE mutations on iron overload in hemodialysis patients was not previously extensively studied. Methods: 36 hemodialysis patients (age 51.3 ± 15.6, (18/18) male/female) and 44 healthy control subjects included in this cross sectional study. Hemoglobin, ferritin, TSAT in the preceding 2 years were recorded. Iron and erythropoietin (EPO) administered during this period were calculated. Iron accumulation in heart and liver was detected by MRI. Relationship between HFE gene mutation, hemoglobin, iron parameters and EPO doses, and tissue iron accumulation were determined. Findings: Iron overload was detected in nine (25%) patients. Hemoglobin, iron parameters, weekly EPO doses, and monthly iron doses of patients with and without iron overload were similar. There was no difference between control group and hemodialysis patients with respect to the prevalence of HFE gene mutations. Iron overload was detected in five of eight patients who had HFE gene mutations, but iron overload was present in 4 of 28 patients who had no mutations (P = 0.01). Hemoglobin, iron parameters, erythropoietin, and iron doses were similar in patients with and without gene mutations. HFE gene mutations remained the main determinant of iron overload after multivariate logistic regression analysis (P = 0.02; OR, 11.6). Discussion: Serum iron parameters were not adequate to detect iron overload and HFE gene mutation was found to be an important risk factor for iron accumulation.     

Extracellular Pectinase Production and Purification from a Newly Isolated Bacillus subtilis Strain

Pectinase is widely used in the fruit juice industry with various aspects, especially to reduce blur in fruit juice. To produce pectinase, Bacillus subtilis were isolated from Kilis soil contaminated by agricultural crop wastes. The extracellular pectinase was purified by using three different technics (cell-free supernatant, ethanol, and ammonium sulphate precipitation) and enzyme activity was measured with spectrophotometric analysis. The maximum specific activity was observed in enzyme preparate purified by ethanol precipitation, 217.44 U/mg. The degradation products of reaction–glucose, saccharose, and fructose–were identified by Fourier transform infrared spectroscopy and thin layer chromatography analysis. Two protein bands belong to pectinase of B. subtilis were determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Molecular weights of bands were approximately calculated as 60 and 64 kDa.     

Silica-based monodisperse PdCo nanohybrids as highly efficient and stable nanocatalyst for hydrogen evolution reaction

Addressed herein, a highly active and stable nanohybrid has been synthesized for hydrogen production. The newly prepared nanocatalysts are silica-based palladium-cobalt nanohybrid structures (PdCo@SiO₂ nanohybrid) (3.82 ± 0.37 nm). The prepared nanohybrids were fully identified with the help of different analytical techniques such as UV-Vis (Ultraviolet-Visible spectroscopy), XPS (X-ray photoelectron spectroscopy), TEM (Transmission electron microscopy), XRD (X-ray diffraction) and HR-TEM (High-resolution transmission electron microscopy) analyses. This prepared nanohybrid was quite successful in the production of hydrogen from DMAB in ambient conditions (TOF: 108.27 h^?1). By the way, it was observed that the DMAB was converted entirely to the product at room temperature with the help of PdCo@SiO₂ nanohybrid. Moreover, monodisperse PdCo@SiO₂ nanohybrid has shown outstanding reusability performance even after 4th usage in the same reaction. As a result, it can be said that the prepared nanohybrid is highly efficient, stable and durable nanocatalyst for the dehydrocoupling of dimethylamine-borane.     

Epidermal Growth Factor Stimulates Extracellular-Signal Regulated Kinase Phosphorylation of a Novel Site on Cytoplasmic Dynein Intermediate Chain 2

Extracellular-signal regulated kinase (ERK) signaling is required for a multitude of physiological and patho-physiological processes. However, the identities of the proteins that ERK phosphorylates to elicit these responses are incompletely known. Using an affinity purification methodology of general utility, here we identify cytoplasmic dynein intermediate chain 2 (DYNC1I-2, IC-2) as a novel substrate for ERK following epidermal growth factor receptor stimulation of fibroblasts. IC-2 is a subunit of cytoplasmic dynein, a minus-end directed motor protein necessary for transport of diverse cargos along microtubules. Emerging data support the hypothesis that post-translational modification regulates dynein but the signaling mechanisms used are currently unknown. We find that ERK phosphorylates IC-2 on a novel, highly conserved Serine residue proximal to the binding site for the p150^Glued subunit of the cargo adapter dynactin. Surprisingly, neither constitutive phosphorylation nor a phosphomimetic substitution of this Serine influences binding of p150^Glued to IC-2. These data suggest that ERK phosphorylation of IC-2 regulates dynein function through mechanisms other than its interaction with dynactin.