Water Structure Modification by Sugars and Its Consequence on Micellization Behavior of Cetyltrimethylammonium Bromide in Aqueous Solution

Water structure modification by sugars with a wide difference in stereoregular structures ranging from monosaccharide to trisaccharide and its consequence on the micellization behavior of cetyltrimethylammonium bromide (CTAB) in aqueous medium have been investigated. The characteristic variation in water absorption peaks in the presence of d(?)fructose has been studied by near-infrared spectroscopy. The analyses show that the hydrogen bonding capability of d(+)glucose, d(?)fructose, sucrose, trehalose and raffinose is mainly responsible for the variation in water-additive interactions. The critical micelle concentration determined by specific conductivity measurement and aggregation number determined by steady state fluorescence quenching method show significant variations in presence of additives for CTAB in aqueous solution. The sugars interact with the water structure to varying extents owing to differences in hydrogen bonding capability depending on the stereoregularity of the structure. This induces differences in the microenvironment for competition between the hydrophobic interaction and degree of hydration of the hydrophilic group of the surfactant to ultimately influence the micellization behavior in aqueous solution.     

Adiabatic small polaron-hopping conduction in Ln0.85Ca0.15MnO3 (Ln=Nd, Pr and Sm) perovskites

Polycrystalline bulk ferromagnetic insulating (FMI) Ln_0.85Ca_0.15MnO₃ (Ln=Nd, Pr and Sm) samples are prepared by standard solid-state reaction route and characterized. Powder X-ray diffraction (XRD) data of the manganites show single-phase character. Existing theoretical models predict that the high temperature (T>θ_D/2, θ_D being the Debye temperature) dc conductivity (σ_dc) of these samples is due to adiabatic small polaron-hopping conduction. Greaves’ and Mott's variable range hopping (VRH) conduction mechanisms are not suitable to explain the σ_dc data at low temperature (T<θ_D/2).     

Removal of radionuclides from low level radioactive liquid waste by precipitation

Six elements in several organs of mice fed with Zn deficient diet (Zn-def. mice) and those fed with control diet (control mice) were analyzed by INAA. Zinc concentrations in the organs of Zn-def. mice were not distinctly lower than those of control mice except for bone and pancreas. However, Ce content increased significantly in all organs of Zn-def. mice compared with control mice, indicating the partial substitution of Co with Zn in metal proteins or other materials for the Zn-def. mice.     

Targeted mass spectrometric strategy for global mapping of ubiquitination on proteins

Post-translational modifications of proteins including phosphorylation, glycosylation, acetylation and ubiquitination facilitate the regulation of many cellular processes and intracellular signaling events. Ubiquitination plays a key role in the functional regulation and degradation of many classes of proteins, and the study of ubiquitination and poly-ubiquitination has emerged as one of the most active areas in proteomic research. A variety of mass spectrometric methods have been described for the identification of ubiquitination sites, the study of poly-ubiquitin topology and the identification of ubiquitin substrates. The most popular workflow for both ubiquitination site mapping and poly-ubiquitination chain topology characterization is to take advantage of the Gly-Gly signature on the substrate's lysine residue observed after tryptic digestion. Although a number of protocols have been described for the mapping of ubiquitination sites, one major challenge is that ubiquitination is typically heterogeneous, and several lysine residues may be ubiquitinated within a protein. When multiple ubiquitination sites are present, multiple analyses are often required to cover all of the potential modification sites which in turn can necessitate the usage of larger quantities of material. In addition, the level of ubiquitination on endogenous and recombinant proteins may be of low intensity, adding further analytical challenges in the identification of this modification. The use of the multiple reaction monitoring (MRM)-initiated detection and sequencing workflow (MIDAS) for the identification of phosphorylation sites has previously been described. Here, we explore the use of an MRM workflow for ubiquitination site mapping on the substrate protein, receptor interacting protein (RIP).     

Inclusion complexes of cyclodextrins with hydrophobic ionic liquids

Two imidazolium-based hexafluorophosphate ionic liquids (ILs), 1-butyl-3-methylimidazolium hexafluorophosphate and 1-dodecyl-3-methylimidazolium hexafluorophosphate, were used to form inclusion complexes (ICs) with α- and β-cyclodextrins (CDs). Formation of the ICs of each CD with each IL was confirmed by the appearance of a characteristic peak in the UV region. Characterisation of the ICs by NMR and FT-IR spectroscopy provided information about the interactions between the host and guest molecules and the structure of the ICs. Temperature-dependent particle size analysis by dynamic light scattering suggested that the size of the host and the guest governs their stability.     

Calcination temperature-dependent morphology of photocatalytic ZnO nanoparticles prepared by an electrochemical–thermal method

ZnO nanoparticles (NPs) with tunable morphologies were synthesized by a hybrid electrochemical–thermal method at different calcination temperatures without the use of any surfactant or template. The NPs were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction, dynamic light scattering, thermogravimetry–differential thermal analysis, scanning electron microscope and N₂ gas adsorption–desorption studies. The FT-IR spectra of ZnO NPs showed a band at 450 cm^?1, a characteristic of ZnO, which remained fairly unchanged at calcination temperatures even above 300 °C, indicating complete conversion of the precursor to ZnO. The products were thermally stable above 300 °C. The ZnO NPs were present in a hexagonal wurtzite phase and the crystallinity of ZnO increased with an increasing calcination temperature. The ZnO NPs calcined at lower temperature were mesoporous in nature. The surface areas of ZnO NPs calcined at 300 and 400 °C were 51.10 and 40.60 m² g^?1, respectively, which are significantly larger than commercial ZnO nanopowder. Surface diffusion has been found to be the key mechanism of sintering during heating from 300 to 700 °C with the activation energy of sintering as 8.33 kJ mol^?1. The photocatalytic activity of ZnO NPs calcined at different temperatures evaluated by photocatalytic degradation of methylene blue under sunlight showed strong dependence on the surface area of ZnO NPs. The ZnO NPs with high surface area showed enhanced photocatalytic activity.     

Electrodeposition of cobalt with tunable morphology from reverse micellar solution

Electrodeposition of cobalt on a copper electrode was successfully performed from aqueous and reverse micellar solutions of a cationic surfactant, cetyltrimethylammonium bromide (CTAB), using constant potential electrolysis method. The potential to be applied for electrodeposition was judged from the cyclic voltammetric behavior of cobalt(II) in aqueous and reverse micellar solutions of CTAB at different compositions. The morphology, dimension, and crystallinity of cobalt deposited onto a copper substrate were evaluated from scanning electron microscopy (SEM) images and X-ray diffraction technique. The cobalt deposited on copper from aqueous solution does not show any definite shape and size, while the deposition from reverse micellar solutions occurred with definite shapes such as star-, flower-, and nanorod-like structures depending on the composition. The slow kinetics governed by the reverse micelles associated with the deposition brings about oriented growth of cobalt onto the copper substrate and offers the potential to electrochemically tune cobalt deposit with desirable morphology.