Hydronium Copper(II)‐tris(5‐nitrotetrazolate) Trihydrate – A Primary Explosive

The long‐time elusive structure of the acid copper(II) salt intermediate in the production of DBX‐1 is presented. The single‐crystal X‐ray shows infinite chains of copper(II) ions complexed by six 5‐nitrotetrazolate anions are aligned along the sixfold axis. Hydronium ions are located on the threefold axis with additional neutral water molecules.     

New Quaternary Sb-Se-Ge-In Chalcogenide Glasses: Linear and Nonlinear Optical Properties

Chalcogenide glasses find extensive applications in infrared (IR) devices and optical communication. Optical parameters of Sb₁₀Se₆₅Ge_25?y In _y thin films, deposited by the thermal evaporation technique, have been analyzed using ultraviolet–visible-near IR spectroscopy. The transitions in the forbidden gap are indirect. The effect of indium (In) alloying on the nonlinear optical parameters has been studied. A shift in optical absorption edge towards higher wavelength shows that the width of the localized states changes, which affects the optical parameters of the system. The high nonlinearity of these glasses makes them suitable for optical regeneration and Raman amplification.     

Effect of CH4/H2 plasma ratio on ultra-low friction of nano-crystalline diamond coating deposited by MPECVD technique

Nano-crystalline diamond coatings were deposited on the silicon substrate using Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD). Experiments were performed by varying the H₂ content in CH₄/H₂ plasma during synthesis. Raman spectral analysis revealed that with decrease in hydrogen content in the CH₄ plasma, the I_D/I_G ratio decreases with the formation of smaller crystallites. Such a film possesses a large grain boundary fraction containing hydrogenated amorphous carbon (a-C:H). During tribological test, sufficient amount of hydrogen present in the grain boundary passivates the dangling σ-bond causing ultra-low friction and extremely low wear evident by improvement in microstructure.     

Graphene supported nickel nanoparticle as a viable replacement for platinum in dye sensitized solar cells

A platinum free counter electrode for dye sensitized solar cells was developed using graphene platelets (GP) supported nickel nanoparticles (NPs) as the active catalyst. Few layered GP were prepared by chemical oxidation of graphite powders followed by thermal exfoliation and reduction. The nanoparticles of nickel were deposited directly onto the platelets by pulsed laser ablation. The composite electrodes of GP and Ni nanoparticles (GP-Ni) thus obtained showed better performance compared to conventional Pt thin film electrodes (Std Pt) and unsupported Ni NPs. The efficiencies of the cells fabricated using GP-Ni, Std Pt and Ni NP CEs were 2.19%, 2% and 1.62%, respectively. The GP-Ni composite solar cell operated with an open circuit voltage of 0.7 V and a fill factor of 0.6. Electrochemical impedance spectroscopy using the I(3)(-)/I(-) redox couple confirms lower values of charge transfer resistance for the composite electrodes, 4.67 Ω cm(2) as opposed to 7.73 Ω cm(2) of Std Pt. The better catalytic capability of these composite materials is also reflected in the stronger I(3)(-) reduction peaks in cyclic voltammetry scans.     

Patulin in apple juices: Incidence and likely intake in an Indian population

The quality and safety of Ayurvedic formulations has become a serious issue, as this Indian system of medicine is used by 80% of the Indian population. Hence, the present study was performed to evaluate heavy metals contents by flame atomic absorbance spectroscopy (AAS) measurements and confirmation by inductive coupled plasma–mass spectroscopy (ICP-MS). A total of 78 formulations (56 herbal, 19 herbometallic and 3 metallic) were sampled. In herbal formulations, lead in 19.6% (11/56), cadmium in 21.4% (12/56), mercury and arsenic in 5.3% (3/56) were above the limit. Lead in 52.6% (10/19) of samples, cadmium in 26.3% (5/19) and mercury and arsenic contained in one herbometallic sample was above the limit. Heavy metals in all metal formulations were above the WHO limit. Significant batch variation was observed. The analytical results of flame AAS and ICP-MS did not differ significantly in the range of measurements in this study, which proves that both methods are satisfactory for estimation of heavy metals in these type of samples.     

Enhancement of Magnetic and Dielectric Properties in Chemically Modified Multiferroic (0.90)BiFe1−x Cr x O3–(0.10)BaTiO3 Nanocomposite

Multiferroic BiFeO₃ and Cr-doped (0.90)BiFe_1?x Cr _x O₃–(0.10)BaTiO₃ (x=0.00, 0.03, and 0.05) nanocomposites were prepared by sol–gel method. Optimum calcination and sintering strategies for obtaining pure perovskite phase have been determined. X-ray diffraction and transmission electron microscope (TEM) were used for the structural and particle size analysis, whereas LCR and SQUID magnetometer was used for dielectric and magnetic measurements. TEM measurements show that the average particle sizes of all the samples were ～19 nm. The dielectric constant was found to be increased twofold in low frequency region with the Cr-doping for x=0.05 in (0.90)BiFe_1?x Cr _x O₃–(0.10)BaTiO₃. The hysteresis curve (M–H) exhibits ferromagnetic nature for all the samples (x=0.0, 0.03, and 0.05) and the spontaneous magnetization at room temperature was found to be 0.63 emu/gm in pure BiFeO₃, which increased to 0.99 emu/gm for x=0.05. Zero-field-cooled (ZFC) and field-cooled (FC) magnetization curves show large discrepancy suggesting spin glass behavior.     

Stabilizing effect in nano-titania functionalized CdS photoanode for sustained hydrogen generation

Efficient and stable photoanode has been fabricated by the surface functionalization of the nanostructured film. For this, the surface of spray deposited CdS thin film was modified through bi-functional molecule mediated chemisorption of TiO₂ nanoparticles (NP). Consequently, a systematic control over efficiency and photoanode stability against corrosion has been investigated. An in-depth quantitative analysis of the photocorrosion of these photoanodes is further studied using chronoamperometry, X-ray photoelectron spectroscopy and induced coupled plasma spectroscopy. TiO₂ NP modified photoanodes show an enhanced efficiency and a stability. For photoelectrochemical (PEC) systems, the stability factor (∑) has been defined for the first time based on the time dependent chronoamperometry, which clearly demonstrates that ∑_modified >> ∑_bare. The modified photoanode shows an improved Incident Photon to Current Efficiency of 22% than the bare CdS (∼8%) electrode. It gives an enhanced solar-to-hydrogen conversion efficiency of STH ∼ 0.7% w.r.t bare CdS (0.2%) under AM 1.5G solar simulator, at 0.2 V/SCE. Improved stability of more than nine hours and enhanced efficiency is attributed to the controlled passivation of CdS surface through TiO₂ NP (5 nm), and inhibition of the charge recombination. Superior and stable performance of modified photoelectrode has been validated by higher and stable hydrogen evolution over modified electrode.     

Study of the adsorption of proteins on stainless steel surfaces using QCM-D

Stainless steel is widely used in a number of industries, ranging from food and dairy to pharmaceuticals. However, fouling associated with protein adsorption constitutes a main issue in such industries, as it decreases the efficiency of stainless steel process equipment and leads to an increase in operational costs due to the need for regular cleaning. In this study, to understand the underlying adsorption phenomena and to identify the mechanisms associated with bio-fouling, adsorption of a set of proteins on 316 grade stainless steel surfaces was studied. Eleven proteins with varying physicochemical properties were tested. The proteins consisted of milk proteins, blood proteins and commercially available proteins. Adsorption experiments were carried out on stainless steel sensors using a quartz crystal microbalance with dissipation at a temperature of 22 °C. The adsorption characteristics of the test proteins were studied and an empirical correlation relating the amount of protein adsorbed to their physical properties is proposed.