Hydrogen bonds in protic ionic liquids and their correlation with physicochemical properties

The temperature dependence of the N-H proton chemical shift in protic ionic liquids (PILs) and FT-IR spectra of the N-H bonds indicated the presence of strong hydrogen bonds between the protonated cation and the anion, depending on the ΔpK(a) of the constituent acid and base, and their successive breaking with temperature, which may explain the characteristic properties of PILs such as relatively low ionicity and its decrease with temperature.     

Acyl hydrazides as peptoid sub-monomers

The use of acyl hydrazides as peptoid sub-monomers is investigated. We demonstrate here that azapeptoids derived entirely from acyl hydrazides can be made conveniently and efficiently using standard peptoid sub-monomer chemistry. Structural studies reveal that the main chain amide bond in these molecules predominantly adopts a trans conformation. A high-quality one bead one compound library of tetramers was made by split and pool synthesis and we found that the identity of the molecule on a single bead could be determined by tandem MALDI mass spectrometry.     

Investigations of zero-field splitting (ZFS) and local distortion parameters of ZnAl2S4:Mn2+ by theoretical analysis

Fourth-order perturbation formula on the basis of the dominant spin-orbit coupling mechanism is employed to investigate the local environment around Mn2+ centers in ZnAl2S4 single crystals. The zero-field splitting (ZFS) parameter D is calculated for the Mn2+ ions at the Al3+ site with local symmetry D3d using the different orbital reduction factors. Both the contributions of the lattice distortions to the crystal-field (CF) parameters and the D are examined by means of different cases. The comparison between the calculated results in this study and the previous experimental and theoretical values reveals a good agreement and reasonable distortion parameters for Mn2+ ions at Al3+ sites.     

Cs2PtI6 Halide Perovskite is Stable to Air,Moisture, and Extreme pH: Application to Photoelectrochemical Solar Water Oxidation

Halide perovskites show incredible photovoltaic power conversion efficiency coupled with several hundreds of hours of device stability. However, their stability is poor in aqueous electrolyte media. Reported here is a vacancy ordered halide perovskite, Cs₂PtI₆, which shows extraordinary stability under ambient conditions (1 year), in aqueous media of extreme acidic (pH 1), basic (pH 13), and under electrochemical reduction conditions. It was employed as an electrocatalyst and photoanode for hydrogen production and water oxidation, respectively. The catalyst remains intact for at least 100 cycles of electrochemical cycling and six hours of hydrogen production at pH 1. Cs₂PtI₆ was employed as a photoanode for PEC water oxidation, and the material displayed a photocurrent of 0.8 mA cm^?2 at 1.23 V (vs. RHE) under simulated AM1.5G sunlight. Using constant voltage measurement, Cs₂PtI₆ exhibited over 12 hours of PEC stability without loss of performance.     

A Robust,Precious-Metal-Free Dye-Sensitized Photoanode for Water Oxidation: A Nanosecond-Long Excited-State Lifetime through a Prussian Blue Analogue

Herein, we establish a simple synthetic strategy affording a heterogeneous, precious metal-free, dye-sensitized photoelectrode for water oxidation, which incorporates a Prussian blue (PB) structure for the sensitization of TiO₂ and water oxidation catalysis. Our approach involves the use of a Fe(CN)₅ bridging group not only as a cyanide precursor for the formation of a PB-type structure but also as an electron shuttle between an organic chromophore and the catalytic center. The resulting hetero-functional PB-modified TiO₂ electrode demonstrates a low-cost and easy-to-construct photoanode, which exhibits favorable electron transfers with a remarkable excited state lifetime on the order of nanoseconds and an extended light absorption capacity of up to 500 nm. Our approach paves the way for a new family of precious metal-free robust dye-sensitized photoelectrodes for water oxidation, in which a variety of common organic chromophores can be employed in conjunction with CoFe PB structures.     

Numerical solution of singularly perturbed fifth order two point boundary value problem

We will consider Adomain decomposition method and the homotopy method to solve a fifth order singularly perturbed BVP arising in viscoelastic flows. The success and pitfalls of the methods will be investigated. Numerical testing will be provided to show the efficiency of the methods proposed. Comparison with the work of others will also be done.     

Synthesis, spectroscopic characterization and alignment of novel azobenzene-containing monomers

A series of novel bifunctionalized photochromic monomers were synthesized, focusing on those with polymerizable acrylic/methacrylic groups attached to both ends of an azobenzene core via flexible spacers. The phase behaviour of the monomers was investigated using DSC, polarizing optical microscopy and X-ray diffraction. The change in UV-vis absorbance of the monomers under illumination with non-polarized/polarized UV light was studied for both solutions and thin films; also studied was its relaxation in the dark. On illumination with LPUV light, in-plane reorientation of the molecules normal to the polarization of the exciting UV light, and aggregation of the molecules in the films, were found.     

Determination of Conjugation Efficiency of Antibodies and Proteins to the Superparamagnetic Iron Oxide Nanoparticles by Capillary Electrophoresis with Laser-Induced Fluorescence Detection

The method based on capillary electrophoresis with laser-induced fluorescence detection (CE/LIF) was developed for determination of magnetic iron oxide nanoparticles (hydrodynamic diameters of 100 nm) functionalized with molecules containing primary amino groups. The magnetic nanoparticles with carboxylic or aminopropyl-trimethoxysilane groups at their surface were conjugated to the model proteins (bovine serum albumin, BSA; streptavidin or goat anti-rabbit immunoglobulin G, IgG) using carbodiimide as a zero-length cross-linker.The nanoparticle–protein conjugates (hydrodynamic diameter 163–194 nm) were derivatized with naphthalene-2,3-dicarboxaldehyde reagent and separated by CE/LIF with a helium–cadmium laser (excitation at 442 nm, emission at 488 nm). The separations were carried out by using a fused-silica capillary (effective length 48 cm, inner diameter 75 um) and 100 mM sodium borate buffer (pH 9.2), the potential was 30 kV. The detection limit for BSA-conjugate was 1.3 pg/10 nl, i.e. about 20 amol. The present method provides an efficient and fast tool for sensitive determination of the efficacy of biomolecular functionalization of magnetic nanoparticles. The CE/LIF technique requires only negligible sample volumes for analysis, which is especially suitable for controlling the process of preparation of functionalized nanoparticles with unique properties aimed to be used for diagnostic or therapeutic purposes.     

Smooth finite abelian uniformizations of projective spaces and Calabi–Yau orbifolds

We give a classification of smooth complex manifolds with a finite abelian group action, such that the quotient is isomorphic to a projective space. The case where the manifold is a Calabi–Yau is studied in detail.     

An efficient technique for finding the eigenvalues of fourth-order Sturm–Liouville problems

In this paper, we will develop a numerical technique for finding the eigenvalues of fourth-order non-singular Sturm–Liouville problems. We used the variational iteration methods as a basis for this technique. Numerical results and conclusions will be presented. Comparison results with others will be presented.