Bimetallic palladium–iridium alloy nanoparticles as highly efficient and stable catalyst for the hydrogen evolution reaction

Addressed herein, a highly efficient, durable and uniformly dispersed activated carbon supported palladium–iridium nanomaterials (3.42 ± 0.34 nm) were reported for the first time as a catalyst in dimethylamine-borane dehydrogenation reaction at the room temperature. The activated carbon supported palladium-iridium nanosheet (Pd–Ir NPs) is obtained by a simple ultrasonic reduction method, and the fabricated nanocatalyst have been defined by Ultra-Violet-Visible (UV–VIS), Raman spectroscopy, X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM) and High-Resolution Transmission Electron Microscopy (HR-TEM). These newly prepared Pd–Ir nanocomposites were found to be highly efficient and stable for dehydrocoupling of dimethylamine borane. The catalytic activity of the Pd–Ir NPs was excellent by showing the one of the best catalytic activity with a very high turnover frequency (295.1 h^?1) and low E_a value of 36.6 ± 2 kJ/mol for DMAB dehydrocoupling. Another important fact about the prepared catalyst is the reusability of the catalyst was very high and easily reused five times without any significant decrease in their catalytic performance. In the current work, the synthesize, characterization and the catalytic performance of the Pd–Ir nanoparticles for the dehydrogenation of the DMAB reaction will be discussed in detail.     

Development of antibacterial fabrics by treatment with Ag-doped TiO2 nanoparticles

This paper deals with the antibacterial properties of nonwoven Co/PET and PP fabrics and woven cotton fabrics treated with the pad-dry-cure (PDC) and electrospray processes. Firstly, the surface modification of nonwoven Co/PET and PP fabrics was carried out to obtain their hydrophilicity by RF-plasma system using acrylic acid as the monomer. Subsequently, Ag-doped TiO₂ nanoparticles prepared by sol–gel and chemical reduction processes using titanium isopropoxide and silver nitrate as precursor were applied to the fabric samples by PDC and electrospray processes. The effect of different synthesis processes of the nanoparticles and various application processes on their antibacterial efficiency was investigated. After RF-plasma pretreatment, the absorbency properties of the fabric samples were measured. The antibacterial activity of fabric samples against Escherichia coli and Staphylococcus aureus was determined qualitatively and quantitatively according to AATCC Method 147 and AATCC Method 100, respectively. The microstructural characteristics and surface morphology of the fabric samples were investigated by SEM-EDX and FTIR-ATR analyses. These results suggest that Ag-doped TiO₂ nanoparticles synthesized by the chemical reduction process imparted good and durable antibacterial activity to nonwoven Co/PET and PP fabrics and woven cotton fabrics for use in wall textiles.     

Determination of metals in fish species from Aegean and Mediterranean seas

Determination of metal levels in muscles and livers of twelve fish species from Aegean Sea and Mediterranean Sea by ICP-AES was made. The levels of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in muscles of fish were <0.01–0.39, <0.01–0.45, 0.07–1.48, 0.51–7.05, 9.18–136, 0.18–2.78, 0.03–1.72, 0.21–1.28 and 3.51–53.5 mg kg⁻¹, respectively. Metal levels in muscles were generally lower than those in livers. Metal concentrations in the edible parts of fish were assessed for human uses according to provisional tolerable weekly intake (PTWI) and provisional tolerable daily intake (PTDI). The estimated values of all metals in muscles of fish in this study were below the established values. Therefore, it can be concluded that these metals in edible parts of the examined species should pose no health problems for consumers.     

Detection and frequency of VT1, VT2 and eaeA genes in Escherichia coli O157 and O157:H7 strains isolated from cattle, cattle carcasses and abattoir environment in Istanbul

The aim of this study was to detect VT1, VT2 and eaeA genes and to determine the frequency of these genes in Escherichia coli O157 and O157:H7 strains isolated from cattle, cattle carcasses and environmental samples of the 5 abattoirs located in Istanbul, Turkey. For this, the presence of VT1, VT2 and eaeA genes in 26 strains of E. coli O157:H7 and 6 strains of O157 was investigated by multiplex-PCR. The results have shown that eaeA gene was detected in all O157 and O157:H7 strains tested. Both VT2 and eaeA genes were detected in 4 (80%) of 5 strains of E. coli O157 and eaeA alone in 1 strain of O157. In 27 strains of O157:H7, 5 (18.5%) strains were found to be positive for VT1, VT2 and eaeA genes, 19 (70.3%) strains for both VT2 and eaeA and, 3 (11.1%) strains for only eaeA gene. Either VT1 alone or VT2 alone was not detected in any strains tested. eaeA gene alone in 2 strains, VT2-eaeA genes in 9 strains and VT1-VT2-eaeA genes in 2 strains were detected in 13 of E. coli O157:H7 strains isolated from cattle. eaeA alone in 1 strain, VT2-eaeA genes in 5 strains and VT1-VT2-eaeA genes in 2 strains were detected in 8 of E. coli O157:H7 strains isolated from carcasses. VT2-eaeA genes in 5 strains (isolated from hands, apron, knife and floor) and VT1-VT2-eaeA genes in 1 strain (isolated from knife) were also detected in 6 of E. coli O157:H7 strains isolated from environmental samples. This study reveals that most of the strains are found to be toxigenic and it is most likely that strains isolated from carcasses and abattoir environment originated from cattle feces. Therefore, HACCP systems are necessary from farm to table especially in the abattoirs to prevent contamination of meat and abattoir environment with intestinal content.     

Comparative typing of <Emphasis Type="Italic">L. delbrueckii</Emphasis> subsp<Emphasis Type="Italic">. bulgaricus</Emphasis> strains using multilocus sequence typing and RAPD–PCR

Comparative typing analysis of 25 Lactobacillus delbrueckii subsp. bulgaricus strains, isolated from traditional yoghurts in Turkey, was performed by RAPD–PCR (randomly amplified polymorphic DNA–PCR) and MLST (multilocus sequence typing). RAPD–PCR analyses were performed using two primers; M13 and 1254. Primer 1254 produced better results than primer M13. The bands produced by primer 1254 were brighter and easier to interpret, and a higher number of bands were produced. In addition, clusters produced by primer 1254 were grouped according to the source of isolation. MLST analysis was performed using three genes, β-gal, pheS and rpoA, and isolates were successfully characterized at strain level. To our knowledge, MLST analyses were used for the first time for strain level discrimination in L. delbrueckii subsp. bulgaricus. It enabled a detailed understanding of L. delbrueckii subsp. bulgaricus strains by using allele and sequence types’ analysis. Both MLST and RAPD allowed for the typing of clusters according to the isolation source, while RAPD provided an increased differentiation. However, by increasing the number of genes analyzed, the discriminatory power of MLST could be increased.     

Hydrogen liberation from the hydrolytic dehydrogenation of hydrazine borane in acidic media

Addressed herein, the hydrolytic dehydrogenation of hydrazine borane (NH₄BH₃, HB) was reported in acidic media using nitric acid (HNO₃) as a catalyst at room conditions. The aqueous hydrazine borane was treated with HNO₃ solution in different concentrations to liberate H₂. Besides, kinetic data were collected to idetificate the activation parameters, the effect of temperature, acid and hydrazine borane concentrations on the hydrogen production for the hydrolytic dehydrogenation of hydrazine borane in acidic media. It can be said that the acid catalyzed hydrazine borane system can be regarded as a simple system for hydrogen production.     

Trimetallic PdRuNi nanocomposites decorated on graphene oxide: A superior catalyst for the hydrogen evolution reaction

In this work, we report an improved catalyst which is superior to known heterogeneous catalysts for dehydrocoupling of dimethylamine-borane (DMAB). The prepared three metallic nanocomposites consist of graphene oxide supported monodisperse palladium, ruthenium and nickel nanomaterials (3.78 ± 0.43 nm). The monodisperse PdRuNi nanoparticles decorated with graphene oxide (PdRuNi@GO) were synthesized according to the microwave synthesis method and characterized by TEM (Transmisson Electron Microscopy), HR-TEM (High Resolution Transmisson Electron Microscopy), XPS (X-ray photoelectron spectroscopy), XRD (X-ray diffraction) and Raman spectroscopy. The prepared trimetallic nanocomposites have shown outstanding performance and stability as a catalyst for the dehydrocoupling of dimethylamine-borane. To the best of our knowledge, the prepared monodisperse PdRuNi@GO nanoparticles have one of the best catalysts with outstanding TOF (Turnover Frequency) value (737.05 1/h) and E_a (55.47 kJ/mol) (activation energy) among all catalysts prepared for dehydrogenation of dimethylamine-borane at low temperatures.