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.     

Properties and phase segregation of crosslinked PCL‐based polyurethanes

Polyurethane (PU) films were prepared from different types of poly(ε‐caprolactone) glycols and hexamethylene diisocyanate without using any other ingredients such as solvent, catalyst, or chain extender. Polymers were stabilized by crosslinking formed as allophanate and/or biuret linkages during the curing process. The effects of different components on the product properties such as chemical structure, microphase segregation, mechanical strength, thermo‐mechanical, thermal properties, and surface hydrophilicities were investigated by FTIR‐ATR, atomic force microscope, mechanical tester, dynamic mechanical analyses, thermogravimetric analyzer, differential scanning calorimetry, and contact angle measurements. Phase separation of hard and soft segments significantly varied depending on the type and molecular weight of diol and triol. Films containing urethane‐urea bonds displayed the maximum phase separation and the highest mechanical strength. Polyols having higher molecular weight increased hydrophilicity while urea bonds caused a reverse effect resulted by bidentate hydrogen bonds. Results showed PUs with various properties can be synthesized via environmentally friendly process without using any solvent or catalyst. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39758.     

Isolation, purification and determination of some biochemical properties of β-glucosidase from Muscat of Bornova grape

This research was undertaken to determine biochemical properties of β-glucosidase (β-d-glucoside glucohydrolase, EC 3.2.1.21) isolated from Muscat of Bornova grape. The optimum pH for β-glucosidase activity was found to be 5.0, and the enzyme showed high activity over a broad pH range of 4.5–6.0. However, due to low activity at pH 3.0, the enzyme is expected to exhibit only a fraction of the maximum activity during grape juice fermentation due to low pH of grape juice. As the temperature increased from 30 to 55 °C, the activity increased, too, the maximum activity occurring at 55 °C which implies that the enzyme is expected to exhibit a low activity at grape juice fermentation. According to thermal inactivation studies, k _D values increased as the temperature increased, whereas half-life and D values decreased. Energy of activation (E _a) and Z values were found to be 120.99 kj mol^?1 (r ² = 0.9776) and 18.08 °C (r ² = 0.9750), respectively. d-glucose and ethyl alcohol inhibited the enzyme at varying degrees depending on the concentration.     

Properties of na‐montmorillonite and cellulose nanocrystal reinforced poly(butyl acrylate‐co‐methyl methacrylate) nanocomposites

Poly(butyl acrylate‐co‐methyl methacrylate) (BA‐co‐MMA) nanocomposite latexes were synthesized in the presence of sodium montmorillonite (Na‐MMT) and cellulose nanocrystal (CNC) as fillers. Nanocomposite preparation with 3 wt% Na‐MMT based upon the total monomer amount was conducted by semi‐batch emulsion polymerization. Furthermore, direct blending of neat copolymer latex with Na‐MMT was performed for comparison. CNC/BA‐co‐MMA nanocomposites were obtained via blending process with varying CNC content (1, 2, and 3 wt %). Good dispersion of both Na‐MMT and CNC within the copolymer matrix was achieved as demonstrated by X‐ray diffraction and transmission electron microscope. Particle size of the nanocomposite latexes was around 120 nm. Thermal, mechanical, and barrier properties of the copolymer showed great improvement with the addition of both Na‐MMT and CNC. CNC nanocomposites displayed enhanced properties with increasing CNC level. Tensile strength of copolymer latex with 3 wt% CNC reached 262.5% of the pristine latex, while tensile strength of Na‐MMT nanocomposite at the same content was 187.5% of the pristine latex. POLYM. ENG. SCI., 55:2922–2928, 2015. © 2015 Society of Plastics Engineers     

Protective effect of Spirulina platensis enriched in phenolic compounds against hepatotoxicity induced by CCl4

Phenolic compounds make up the major secondary metabolites with high pharmaceutical potential. Microalgae were reported to contain low amounts of phenolic compounds. The present study aimed to investigate the hepatoprotective potential of biomass of Spirulina platensis enriched in phenolic compounds. The protective effects of the biomass of S. platensis with low amounts of phenolics (SP1) and with high amounts of phenolics (SP2) against CCl₄-induced acute hepatotoxicity were evaluated in rats. The increased levels of ALT, AST and MDA along with decreased activities of SOD and CAT were significantly (p < 0.01) ameliorated by SP2. Histological examinations revealed that SP2 was more potent than SP1 in protecting the liver from toxic injury of CCl₄ and preserving the hepatocyte ultrastructure. The lesions including necrosis, lymphocyte infiltration, ballooning degeneration and hepatocyte injury as irregular lamellar organisation, dilations in endoplasmic reticulums and the presence of great number of cytoplasmic vacuolization were healed by SP2.     

Clinical experience on headache in children: analysis of 92 cases

We analyzed, retrospectively, 92 patients with headache to determine the changes in the order of frequency of causes with the development of neuroimaging studies and its efficacy in the investigation of patients with headache. The type of headache was redefined according to the International Headache Society (IHS) diagnostic criteria. Migraine was the most frequent cause of headache and the rest in decreasing order were: tension-type headache, sinusitis, and epilepsy. The percentage of the findings relevant to headache in computed tomographic (CT) scans, magnetic resonance images (MRIs), Waters' projection (radiographs), and electroencephalograms (EEGs) were respectively 4.2%, 33.3%, 16%, and 25%. Neuroimaging studies are not necessary in the routine evaluation of patients with headache unless there is an abnormality in the findings. When it is needed, MRI, which has higher yield, can take the place of CT scanning. The most important point is taking a proper history of headache and making a thorough physical and neurologic examination of the patient.     

Operational Conditions of Activated Sludge: Influence on Flocculation and Dewaterability

Selected operational conditions of activated sludge are investigated in relation to their effect on flocculation and dewatering. Semi-continuous reactors with 2 -L volume were operated at different mean cell residence times, C/N ratios, and three different influent cations. Results show that MCRT, C/N ratio, and the cation type affect the bioflocculation capacity of activated sludge measured by the quantity of extracellular polymeric substances. As the MCRT value operated in the reactors and the C/N ratio of the influent wastewater increase, total amount of polymers produced increases. High MCRT values and low C/N values cause good dewatering of the sludge. All cations are shown to stimulate the EPS production in a way that the highest total EPS concentrations are observed at the highest cation dosages. The dewaterability of the sludges improves only with increasing calcium and magnesium concentrations and deteriorates with increasing potassium concentration.     

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.     

Correlation between sealer penetration into dentinal tubules and bond strength of two new calcium silicate-based and an epoxy resin-based,endodontic sealer

The relationship between sealer penetration into dentinal tubules and the bond strength of two new calcium silicate-based and epoxy resin-based endodontic sealers was evaluated. Thirty recently extracted human maxillary incisors were instrumented and divided into three groups according to the sealer used: (1) AH Plus; (2) iRoot SP; and (3) MTA Fillapex. Sealer penetration into dentinal tubules was measured using CLSM. Then, a universal testing machine was used to compare the push-out bond strengths of the sealers to the root canal dentin. AH Plus and MTA Fillapex exhibited significantly higher sealer penetration than iRoot SP did (p > .05). The push-out bond strengths of AH Plus and iRoot SP were higher than that of MTA Fillapex. We concluded that greater penetration of the sealer into the dentinal tubules was not associated with higher bond strength among the three sealers tested.