Relaxation dynamics in glycerol-water mixtures: I. Glycerol-rich mixtures

We discuss the relaxation dynamics of glycerol-water mixtures, as studied by dielectric spectroscopy in the frequency range from 1 Hz to 250 MHz and at temperatures between 173 and 323 K. The experimental results obtained for the glycerol-rich mixtures suggest that the main dielectric relaxation process, as well as the so-called high-frequency "excess wing" (EW) and dc conductivity, follow the same temperature dependence. This result indicates that all of these processes are induced by the same molecular origin. A new phenomenological function is proposed to describe the whole dielectric spectrum in the covered frequency range, and some possible mechanisms of dielectric behaviors through the dc conductivity, the main relaxation process, and the EW are discussed.     

PREPARATION OF PHOTOFUNCTIONAL POLYMER THIN FILMS BY LANGMUIR-BLODGETT TECHNIQUE

Polymer LB films containing photofuntional groups were prepared by the copolymerization of N-dodecylacrylamide (DDA), which has an excellent property to form a stable monolayer and LB multilayerswith photofunctional monomers. Tris(2, 2'-bipyridine) ruthenium complex, Ru(bpy)_3~(2+), one of the most well-known redox-active sensitizer, was incorporated into the DDA copolymer. The photogalvanic effect based onthe photoinduced electron transfer using the ruthenium complex in the polymer LB monolayer was discussed.     

Synthesis of oligonucleotides possessing versatile probes for PET labelling and their rapid ligand-free click reaction

We synthesised aryl acetylene derivatives as versatile probes for labelling of oligonucleotides. RNA oligomers bearing an aryl acetylene molecule rapidly reacted with benzylazide derivatives under ligand-free click reaction conditions.     

水溶性导电高分子聚噻吩及其水凝胶的掺杂行为研究

用碘和高氯酸作掺杂剂对水溶性导电高分子聚（3-羧甲基噻吩）及其水凝胶的掺杂行为进行了系统研究。结果发现水溶胀聚（3-羧甲基噻吩）凝胶及其高分子很容易被高氯酸或碘的水溶液进行掺杂，且其掺杂能力强烈依赖于掺杂剂溶液浓度。对碘掺杂的高分子溶液，其掺杂过程不很稳定同时伴随着脱掺杂过程的发生，而对于聚噻吩凝胶，高氯酸极易使其掺杂，而且一旦掺杂则在掺杂状态下具有相对的稳定性。     

On a property specific to the tent map

Let a set {X_λ; λ  Λ} of subspaces of a topological space X be a cover of X. Mathematical conditions are proposed for each subspace X_λ to define a map g_Xλ:X_λ→X which has the following property specific to the tent map known in the baker’s transformation. Namely, for any infinite sequence ω₀, ω₁, ω₂, … of X_λ, λ  Λ, we can find an initial point x₀  ω₀ such that g_ω0(x₀)ω₁,g_ω1(g_ω0(x₀))ω₂,…. The conditions are successfully applied to a closed cover of a weak self-similar set.     

Nuclear resonance vibrational spectroscopy reveals the FeS cluster composition and active site vibrational properties of an O2-tolerant NAD+-reducing [NiFe] hydrogenase

Hydrogenases are complex metalloenzymes that catalyze the reversible splitting of molecular hydrogen into protons and electrons essentially without overpotential. The NAD⁺-reducing soluble hydrogenase (SH) from Ralstonia eutropha is capable of H₂ conversion even in the presence of usually toxic dioxygen. The molecular details of the underlying reactions are largely unknown, mainly because of limited knowledge of the structure and function of the various metal cofactors present in the enzyme. Here, all iron-containing cofactors of the SH were investigated by ⁵⁷Fe specific nuclear resonance vibrational spectroscopy (NRVS). Our data provide experimental evidence for one [2Fe2S] center and four [4Fe4S] clusters, which is consistent with the amino acid sequence composition. Only the [2Fe2S] cluster and one of the four [4Fe4S] clusters were reduced upon incubation of the SH with NADH. This finding explains the discrepancy between the large number of FeS clusters and the small amount of FeS cluster-related signals as detected by electron paramagnetic resonance spectroscopic analysis of several NAD⁺-reducing hydrogenases. For the first time, Fe–CO and Fe–CN modes derived from the [NiFe] active site could be distinguished by NRVS through selective ¹³C labeling of the CO ligand. This strategy also revealed the molecular coordinates that dominate the individual Fe–CO modes. The present approach explores the complex vibrational signature of the Fe–S clusters and the hydrogenase active site, thereby showing that NRVS represents a powerful tool for the elucidation of complex biocatalysts containing multiple cofactors.     

Oxo-tethered ruthenium(II) complex as a bifunctional catalyst for asymmetric transfer hydrogenation and H2 hydrogenation

Newly developed oxo-tethered Ru amido complexes (R,R)-1 and their HCl adducts (R,R)-2 exhibited excellent catalytic performance for both asymmetric transfer hydrogenation and the hydrogenation of ketonic substrates under neutral conditions without any cocatalysts to give chiral secondary alcohols with high levels of enantioselectivity.     

Effects of Temperature and Mobile Phase Condition on Chiral Recognition of Poly(l-phenylalanine) Chiral Stationary Phase

Characteristics of the chiral stationary phase with poly(l-phenylalanine) peptide selector, which was in ??-helical state, was reported. Since environmental factors affect peptide conformation, the changes in enantioselectivity were examined depending on column temperature and mobile phase conditions (ionic strength, pH, mobile phase composition). Column temperature and pH drastically affected the enantioselectivity. Based on these changes, the relation between chiral recognition and secondary structure of the peptide selector was discussed. The column stability during sequential analysis under different separation conditions was also evaluated.     

SUPER TOUGH GELS WITH A DOUBLE NETWORK STRUCTURE

Living tissues work with fantastic functions in soft and wet gel-like state.Thus,hydrogels have attracted much attention as excellent soft and wet materials,suitable tot making artificial organs for medical treatments.However, conventional hydrogels are mechanically too weak for practical uses.We have created double network (DN) hydrogels with extremely high mechanical strength in order to overcome this problem.DN gels are interpenetrating network (IPN) hydrogels consisting of rigid polyelectrolyte and s...