Catalytic hydrolysis of sodium borohydride solution for hydrogen production using thermal plasma synthesized nickel nanoparticles

In the present study nickel nanoparticles were synthesized by thermal plasma route. In this method we obtained highly crystalline almost spherical nanoparticles with maximum number of particles having size around 30–50 nm. These nanoparticles were thoroughly characterized and employed as a catalyst for hydrogen production using hydrolysis of sodium borohydride (NaBH₄). The effect of initial concentration of NaBH₄, pH and temperature of solution on the rate of hydrogen production was investigated. Nickel nanoparticles exhibits first order reaction with respect to NaBH₄ concentration at elevated temperatures. After hydrolysis, the nickel nanoparticles showed presences of B–O and B–OH species on the nickel surface. The catalyst was found to be stable during 5 sequential cycles of test.     

TiO2–CdS supported CuNi nanoparticles as a highly efficient catalyst for hydrolysis of ammonia borane under visible-light irradiation

TiO₂–CdS nanotubes (NTs) were used for the first time as a support to load metal nanoparticles (NPs) for the hydrolysis of ammonia borane (AB) which is a new strategy. The TiO₂–CdS NTs support was first synthesized using a hydrothermal method, and then the CuNi NPs were loaded using a liquid-phase reduction method. The synthesized samples were characterized by XRD, SEM-EDS, TEM, XPS, ICP, UV–Vis, and PL analyses. The characterization results show that the CuNi NPs existed in the form of an alloy with a size of ~1.2 nm and uniformly dispersed on the support. Compared with their single metal counterparts, the bimetallic CuNi-supported catalysts showed a higher catalytic activity in the hydrolysis of AB under visible-light irradiation: Cu_0·45Ni_0·55/TiO₂–CdS catalyst had the fastest hydrogen evolution rate with a high conversion frequency (TOF) of 25.9 mol_H2·mol_cat⁻¹ min⁻¹ at 25 °C and low activation energy of 32.8 kJ mol⁻¹. Cu_0.45Ni_0.55/TiO₂–CdS catalyst showed good recycle performance, maintaining 99.3% and 85.6% of the original hydrogen evolution rate even after five and ten recycles, respectively. Strong absorption of visible light, improved electron–hole separation efficiency, and metal synergy between Cu and Ni elements played a crucial role in improving the catalytic hydrolysis performance of AB. The catalyst prepared in this study provides a new strategy for the application of photocatalysts.     

Impact of an Engineered Copper-Titanium Dioxide Nanocomposite and Parent Substrates on the Bacteria Viability,Antioxidant Enzymes and Fatty Acid Profiling

Due to the systematic increase in the production of nanomaterials (NMs) and their applications in many areas of life, issues associated with their toxicity are inevitable. In particular, the performance of heterogeneous NMs, such as nanocomposites (NCs), is unpredictable as they may inherit the properties of their individual components. Therefore, the purpose of this work was to assess the biological activity of newly synthesized Cu/TiO₂-NC and the parent nanoparticle substrates Cu-NPs and TiO₂-NPs on the bacterial viability, antioxidant potential and fatty acid composition of the reference Escherichia coli and Bacillus subtilis strains. Based on the toxicological parameters, it was found that B. subtilis was more sensitive to NMs than E. coli. Furthermore, Cu/TiO₂-NC and Cu-NPs had an opposite effect on both strains, while TiO₂-NPs had a comparable mode of action. Simultaneously, the tested strains exhibited varied responses of the antioxidant enzymes after exposure to the NMs, with Cu-NPs having the strongest impact on their activity. The most considerable alternations in the fatty acid profiles were found after the bacteria were exposed to Cu/TiO₂-NC and Cu-NPs. Microscopic images indicated distinct interactions of the NMs with the bacterial outer layers, especially in regard to B. subtilis. Cu/TiO₂-NC generally proved to have less distinctive antimicrobial properties on B. subtilis than E. coli compared to its parent components. Presumably, the biocidal effects of the tested NMs can be attributed to the induction of oxidative stress, the release of metal ions and specific electrochemical interactions with the bacterial cells.     

Preparation of Aqueous Nanodispersions of Disperse Dye by High-Gravity Technology and Spray Drying

Disperse dyes are poorly water-soluble and difficult to stably disperse in an aqueous medium, which greatly limits their application in dyeing synthetic fibers. Micronization can solve this problem. Herein, a facile way to prepare stable aqueous nanodispersions of disperse dye (C.I. disperse yellow 54) is presented by combining high-gravity antisolvent precipitation in a rotating packed bed (RPB) with spray drying. The as-prepared product had an average particle size of 120 nm, which could be readily redispersed in water. Compared with raw dye, the wettability and dispersibility of disperse dye nanoparticles were remarkably improved. Furthermore, the dyeing properties of the nanodispersions were obviously better than those of the commercial dye, which was micronized by ball milling.     

Pt–Ru nanoparticles anchored on poly(brilliant cresyl blue) as a new polymeric support: Application as an efficient electrocatalyst in methanol oxidation reaction

The glassy carbon electrode is modified by poly(brilliant cresyl blue) (PBCB) to be applied as a new green and efficient platform for Pt and Pt–Ru alloy nanoparticles deposition. Surface composition, morphology and catalytic activity of these modified electrodes towards methanol oxidation are assessed by applying X-ray diffraction, field emission scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy techniques. The X-ray diffraction patterns reveal that the highly crystalline Pt and Pt–Ru alloy and RuO₂ nanoparticles with low crystallinity are deposited on the PBCB modified glassy carbon electrodes. The microscopic images indicate smaller size and better distribution of deposited nanoparticles on the surface of PBCB modified electrodes. Cyclic voltammetry and electrochemical impedance spectroscopy results reveal that PBCB supported Pt and Pt–Ru nanoparticles have better electrocatalytic performance and durability towards methanol oxidation rather than the unsupported nanoparticles. From the obtained results it can be concluded that the presence of PBCB not only improves the stability of nanoparticles on the surface, but also leads to the formation of smaller size and more uniform distribution of nanoparticles on the surface, which, in turn, cause the nanoparticles to provide a higher accessible surface area and more active centers for the oxidation of methanol. The results will be valuable in extending the applications of this polymer in surface modification steps and in developing promising catalyst supports to be applied in direct methanol fuel cells.     

Microcapacitors with controlled electrical capacity in the pF–nF range printed by laser-induced forward transfer (LIFT)

Micrometric-sized pixels of hybrid organic–inorganic thin films (Ag/parylene-C) have been printed by laser-induced forward transfer (LIFT) on flexible, cost-efficient substrates. Micrometric capacitors have been fabricated by laser printing such pixels together with silver nanoparticles (AgNP) paste. The AgNP paste has been deposited in the shape of square pads, acting as bottom electrode. This combination is suitable to be used in microelectronic circuits, as the electrical components exhibit controllable capacity in the pF–nF range. Electrical characterizations of the printed pixels demonstrate that the capacitors are fully operative and stable over time.     

Monoclonal antibody‐targeted polymeric nanoparticles for cancer therapy – future prospects

Although combination therapy for cancer utilising monoclonal antibodies in conjunction with chemotherapeutic drugs has resulted in increases in 5 year survivals, there nevertheless remains significant morbidity and mortality associated with systemic delivery of cytotoxic drugs. The advent of living radical polymerisation has resulted in complex and elegant nanoparticle structures that can be engineered to passively target a drug payload for cancer treatment. This presents a therapeutic modality whereby biodistribution and consequently systemic toxicity can be reduced, while focusing drug delivery to the tumour site. Nanoparticle delivery can be enhanced by attachment of a targeting monoclonal antibody fragment to facilitate tumour cell uptake through endocytosis, and so increase therapeutic efficacy. In this way, monoclonal antibodies can be supercharged by carrying a payload consisting of a cocktail of conventional chemotherapeutic drugs and siRNA. This review will focus on antibody‐targeted polymeric nanoparticles to cancer cells, and methods and technologies for synthesising such antibody‐targeted nanoparticles. The review is confined to polymeric‐based nanoparticles as these offer some advantages over liposomal nanoparticles and may circumvent some of the pitfalls in nanomedicine. Development of these antibody based polymeric nanoparticles and future directions for therapy are highlighted in this review. © 2014 Society of Chemical Industry     

The influence of different water types and brewing durations on the colloidal properties of green tea infusion

Green tea infusions were prepared with three different water types: distilled water, commercial mineral water and CaCl₂ added distilled water (at 20 mg L^?1). The impact of different water type on the colloidal particle parameters, namely size, polydispersity index (PDI) and zeta potential, was examined within 24 h. Our results indicate that distilled water green tea infusion (DWT) brewed at 80 °C for 5 min contained the smallest particles (242.17 ± 11.78 nm) as examined by dynamic light scattering (DLS). Moreover, DWT showed smaller size increase during the 24 h storage than that of mineral water tea and CaCl₂ added water tea infusion. The morphology characteristics of green tea infusion particles were visualised by transmission electron microscope (TEM) which revealed that green tea infusion particles had heteromorphic shapes. Our results suggest that mineral composition of water impacts the colloidal size and stability of green tea infusion. Additionally, DLS and TEM could be useful tools to provide colloidal information which is important to understand quality characteristics of green tea infusion during processing and storage.