A hetero-core structured fiber optic pH sensor

Novel spectroscopic sensor based on a hetero-core structured fiber optic is described in this paper. The hetero-core structured fiber optic consists of multi mode fibers and a short piece of single mode fiber which was inserted in the multi mode fibers. Phenol red and/or cresol red as pH sensitive dyes were immobilized on the surface of the hetero-core portion by using sol-gel method, and the pH change detection was performed by immersing the hetero-core portion into the solution. In the case that the cresol-red immobilized fiber was immersed in the alkaline and/or acidic solution, the peak wavelength of the propagating loss spectra were about 575 and 545 nm, respectively. These propagating loss spectra were similar to that of the absorbance spectra of the dye solution. In the propagating loss spectra of phenol-red immobilized fiber, these spectra were similar to that of the dye solution. The colorimetric change of the dye in the support matrix was reversible, and the response time of the sensor was within 30 s.     

Structural development of liver X receptor (LXR) antagonists derived from thalidomide-related glucosidase inhibitors

Following our previous discovery of LXR antagonistic activity of 2'-substituted phenylphthalimides derived from thalidomide-related glucosidase inhibitors, structure-activity studies and further structural development led to 5-chloro-N-2'-n-pentylphenyl-1,3-dithiophthalimide (5CPPSS-50), with IC50 values of about 10 and 13 microM for LXRalpha and LXRbeta, respectively.     

Interlayer water molecules in vanadium pentoxide hydrate. IX. Anisotropic translational diffusion leading to anisotropic ac conductivity

The anisotropy of the dynamic properties of interlayer water molecules along the a and b axes of vanadium pentoxide hydrate, orthorhombic V2O5.nH2O, was studied using quasielastic neutron scattering (QENS) in relation to the anisotropy of the ac conductivity. The QENS spectra were analyzed using a stretched exponential function and a Lorentzian function. Both methods showed that the double-layer water molecules along the b axis are more mobile than those along the a axis. The difference in mobility between the two axes is more pronounced using a Lorentzian function analysis. These facts suggest that the diffusion coefficient of water molecules along the b axis is larger than that along the a axis, which is closely related to the ac conductivity originating from proton hopping. The anisotropy of the dynamic motion of water molecules can be attributed to the shorter b-axis length (b=3.60 A), with respect to the longer and less regular repetition of the atomic arrangements along the a axis (42.34 A).     

Adsorption behaviors of high-valence metal ions on desferrioxamine B immobilization nylon 6,6 chelate fiber under highly acidic conditions

Adsorption behaviors of the high-valence metal ions Zr(IV), Hf(IV), Ti(IV), V(V), Nb(V), Ta(V), and Mo(IV) on desferrioxamine B (DFB) immobilization nylon 6,6 chelate fiber was investigated under highly acidic conditions. Though the complexes of DFB and the high-valence metal ions were extracted without selectivity by solvent extraction, the only zirconium ions showed higher adsorption percentages than that of other high-valence metal ions on the DFB immobilization nylon 6,6 chelate fiber. Adsorption properties were caused that limited the freedom of DFB by chemical immobilization. Especially, hafnium ions and zirconium ions, which have similar chemical properties, showed different adsorption behavior in highly acidic aqueous solutions. Zirconium ions were quantitatively adsorbed up to 13.5 micromol/g.     

Observation of characteristic IR band assignable to dimerized copper ions in montmorillonite

Copper ion-exchanged montmorillonite clays, which had been prepared by ion exchange in an aqueous solution of CuCl(2) at a temperature above 323 K, exhibited the characteristic IR band in the region 3360-3310 cm(-1). No such bands were observed for the samples prepared by using different ion-exchange solutions and at different temperatures. From the spectroscopic observations, it was revealed that the ion-exchanged copper ions (Cu(2+)) are in the form of dimerized species by bridging two hydroxyls, [Cu(2+) <(OH(-)(2) > Cu(2+)], in montmorillonite.     

Denaturation of alpha-lactalbumin and ubiquitin studied by electrospray and laser spray

Electrospray and laser spray mass spectra of human alpha-lactalbumin and bovine ubiquitin were studied, with an emphasis on the denaturation induced by laser spray. There were no remarkable differences in the electrospray and laser spray mass spectra for acidic and basic aqueous solutions of alpha-lactalbumin in positive and negative modes of operations. This originates from the fact that this protein is tightly folded with four disulfide bonds. For ubiquitin, however, denaturation was induced by laser spray for the positive mode of operation and the [M+nH](n+) with a maximum of n = 13 was observed, i.e., all the acidic amino acid residues are fully neutralized (protonated). In contrast, the laser-induced denaturation was not observed for the negative mode of operation, i.e., denaturation of ubiquitin is largely suppressed in the negatively charged liquid droplets. The marked difference observed in the positive and negative modes of operations for ubiquitin is ascribed to the difference in the susceptibility of side-chain/main-chain interactions in the positive-ion excess and in the negative-ion excess liquid droplets. That is, the interactions between the basic residues and main-chain amide carbonyl groups (-NH(3) (+)***O=C< or -NH(2)***O=C<) which play an important role in stabilizing the protein structures are not so affected in the negative mode of operation but are weakened in the positive mode of operation.     

Catalytic <Emphasis Type="Italic">N</Emphasis>-Alkylation of Amines with Primary Alcohols over Halide Clusters

Piperidine was reacted with methanol under a hydrogen stream in the presence of (H₃O)₂[(W₆Cl₈)Cl₆]·6H₂O supported on silica gel. When the temperature was raised above 200 °C, the catalytic activity of the cluster appeared. Piperidine N-methylation proceeded yielding N-methylpiperidine in 95% selectivity at 350 °C. The corresponding halide clusters of niobium, molybdenum, and tantalum supported on silica gel also catalyzed the reaction. Primary alcohols such as ethanol and 1-propanol produced the corresponding N-alkyl products of piperidine; however, secondary and tertiary alcohols did not. Selective N-methylation of pyrrolidine, hexamethyleneimine, butylamine, and aniline also proceeded. Thus, the clusters catalyzed alkylation of aliphatic, alicyclic, and aromatic amines with primary alcohols. A Brønsted acid site attributable to a hydroxo ligand, which is formed on the cluster complex by thermal activation, is proposed as the active site of the catalyst.     

Effect of shift in refractive index of dispersive elements in waveband-shift-free optical-phase conjugator based on DFG

Optical Review - In this study, the effect of the shift in the refractive index between two dispersive elements on the output phase-conjugated (PC) wave power of waveband-shift-free optical-phase...