Tagging of avidin immobilized beads with biotinylated YAG:Ce3+ nanocrystal phosphor

YAG:Ce³⁺ nanoparticles 9.5 ± 1.2 nm in diameter have been synthesized from aluminium isopropoxide and acetates of yttrium and cerium in 1,4-butanediol (1,4-BD) by autoclave treatment at 300 °C for 2 h. After replacing 1,4-BD by ultrapure water, NH₂ groups were introduced on the surface of YAG:Ce³⁺ nanoparticles by addition of 3-aminopropyltrimethoxysilane then biotinylation with sulfo-NHS-LC-biotin. We demonstrated that avidin immobilized beads are tagged by biotinylated YAG:Ce³⁺ nanoparticles by the selective avidin-biotin interaction, furnishing a green fluorescent image on excitation with blue light. This result indicates that YAG:Ce³⁺ nanoparticle phosphors have much potential in biological applications.     

Practical access to the polymer incarcerated platinum (PI Pt) catalyst and its application to hydrogenation

Polymer incarcerated platinum catalysts (PI Pt) were conveniently prepared from PtCl(2)(COD) or H(2)PtCl(6).6H(2)O and styrene copolymers via reduction of the Pt sources with triethylamine, coacervation, and cross-linking. The Pt catalysts have been successfully applied to catalytic hydrogenation including saturation of heterocyclic compounds.     

Synthesis and inhibitory activity of 8-substituted 2-deoxy-beta-KDO against CMP-KDO synthetase

3-Deoxy-D-manno-octulosonate cytidyltransferase (CMP-KDO synthetase) is involved in the biosynthesis of lipopolysaccharide (LPS) which is an essential component of the outer membrane of gram-negative bacteria. New CMP-KDO synthetase inhibitors, 8-substituted derivatives of 2-deoxy-beta-KDO (2) have been prepared. Compounds 8, 11, 15 and 16 in which the 8-hydroxyl group of 2 is replaced by guanidine, di(carbamoylethyl)amino, p-methoxy- or p-nitro-benzyloxycarbonylamino, respectively affect moderately the CMP-KDO synthetase activity.     

ISOLATION OF BLEPHARISMIN-BINDING 200 kDa PROTEIN RESPONSIBLE FOR BEHAVIOR IN Blepharisma

Abstract— The ciliated protozoan, Blepharisma, shows an avoidance reaction (step-up photophobic response) in response to light stimulation. A profile of a gel-permeation of a crude detergent-solubilized sample of the cells resulted in several red-colored fractions. Among these blepharismin-containing fractions, the fractions III-V did not contain amino acids. The peak of fraction II monitored by 580 nm absorbance was much smaller. A prominent peak appeared in fraction I, which contained a large amount of amino acids. The absorption spectrum of fraction I was well fitted to the action spectrum of the step-up photophobic response, although free pigment (blepharismin) also fitted. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of this fraction resulted in a thicker band corresponding to molecular mass of 200 kDa. These results suggest that the 200 kDa chromoprotein (blepharismin-protein complex) is responsible for the step-up photophobic response in Blepharisma. The absorption spectrum of free chromophore dissociated from the chromophore-protein complex was identical to free red pigment termed blepharismin. The absorption spectrum of the other fractions agreed with that of thin-layer chromatography-purified red pigment, indicating that the pigments contained in these fractions are free pigment dissociated from the chromophore-protein complex.     

Pt nanoworms: creation of a bumpy surface on one-dimensional (1D) Pt nanowires with the assistance of surfactants embedded in mesochannels

A new type of platinum nanowire with a bumpy surface "Pt nanoworm" is electrochemically synthesized in mesochannels of mesoporous silica films with the assistance of a nonionic surfactant (C(16)EO(8)).     

Pressure-induced structural, magnetic, and transport transitions in the two-legged ladder Sr3Fe2O5

The layered compound SrFeO(2) with an FeO(4) square-planar motif exhibits an unprecedented pressure-induced spin state transition (S = 2 to 1), together with an insulator-to-metal (I-M) and an antiferromagnetic-to-ferromagnetic (AFM-FM) transition. In this work, we have studied the pressure effect on the structural, magnetic, and transport properties of the structurally related two-legged spin ladder Sr(3)Fe(2)O(5). When pressure was applied, this material first exhibited a structural transition from Immm to Ammm at P(s) = 30 ± 2 GPa. This transition involves a phase shift of the ladder blocks from (1/2,1/2,1/2) to (0,1/2,1/2), by which a rock-salt type SrO block with a 7-fold coordination around Sr changes into a CsCl-type block with 8-fold coordination, allowing a significant reduction of volume. However, the S = 2 antiferromagnetic state stays the same. Next, a spin state transition from S = 2 to S = 1, along with an AFM-FM transition, was observed at P(c) = 34 ± 2 GPa, similar to that of SrFeO(2). A sign of an I-M transition was also observed at pressure around P(c). These results suggest a generality of the spin state transition in square planar coordinated S = 2 irons of n-legged ladder series Sr(n+1)Fe(n)O(2n+1) (n = 1, 2, 3, ...). It appears that the structural transition independently occurs without respect to other transitions. The necessary conditions for a structural transition of this type and possible candidate materials are discussed.     

Phase behaviour of three homologues of the discotic hexa‐n‐alkoxyanthraquinones under pressure

The phase transition behaviour of three homologous discotic mesogens, the hexa‐n‐alkoxyanthraquinones HOAQ(n), n indicating the number of carbon atoms in the alkoxy group, was investigated under hydrostatic pressures up to 500?MPa using a high pressure differential thermal analyser. The T vs. P phase diagrams of HOAQ(6), HOAQ(8) and HOAQ(9) were constructed for solution‐ (Cr₀) and melt‐crystallized (Cr₁) samples of the compounds. HOAQ(6) shows the reversible Cr₀–rectangular columnar phase (Col_r)–hexagonal columnar phase (Col_h)–isotropic liquid (I) phase sequence at atmospheric pressure. The stable Col_r phase of HOAQ(6) has a decreased temperature range with increasing pressure and then the Col_r phase disappears under pressures above about 350?MPa; instead the Cr₀–Col_h–I phase sequence is exhibited. For HOAQ(8), the solution‐grown sample exhibits the stable Cr₀–Col_h–I phase sequence at atmospheric pressure. Applying pressure to the solution‐grown sample induces the formation of the stable Col_r phase in the pressure region between 10 and 350?MPa, leading to the Cr₀–Col_r–Col_h–I phase sequence. The pressure‐induced Col_r phase disappears under higher pressures. The melt‐cooled sample of HOAQ(8) shows the formation of the metastable crystal (Cr₁), unknown mesophase (X) and Col_r phases at lower temperatures under atmospheric pressure, and exhibits the reversible Cr₁–X–Col_r–Col_h–I phase sequence on subsequent thermal cycles. The metastable phase sequence was observed under pressures up to 100?MPa, but the phase transitions were too small to be detected under higher pressures. In HOAQ(9) the stable Cr₀–Col_h–I phase sequence is observed at all pressures, while the melt‐cooled sample shows the metastable Cr₁–Col_r–Col_h–I phase sequence under pressures up to 300?MPa. The metastable Col_r phase disappears under higher pressures.     

One-pot dehydrogenation of carboxylic acid derivatives to α,β-unsaturated carbonyl compounds under mild conditions

Carboxylic acid derivatives such as N-acyl-2-oxazolidones, δ-lactones, and δ-lactams were smoothly dehydrogenated to the corresponding α,β-unsaturated carbonyl compounds in one-pot manner at −78 °C just by treating their lithium enolates with N-tert-butylbenzenesulfinimidoyl chloride.     

Thermal behaviour under pressure of the thermotropic cubic mesogen 4'- n -alkoxy-3'-nitrobiphenyl-4-carboxylic acids

The thermal behaviour of members of a homologous series which exhibits the optically isotropic cubic phase, the 4'- n -alkoxy-3'-nitrobiphenyl-4-carboxylic acids having alkoxy chains containing 16, 20 and 22 carbon atoms (referred to as ANBC-16, -20 and -22, respectively) was investigated under pressures up to 200-400 MPa by high pressure differential thermal analysis. In the phase diagram of ANBC-16 obtained on heating, a triple point was estimated at 54 ±1 MPa and 205 ±1°C for the SmC, Cub and SmA phases. It was found that the X phase is formed on cooling under all pressures, while appearing on heating at high pressures above about 54 MPa. Thus the X phase appears monotropically between the SmA and Cub phases in the low pressure region and enantiotropically between the SmA and SmC phases under higher pressures. It is strongly suggested that the X phase is a columnar mesophase. For ANBC-20 and -22, the cubic phase tends to be destabilized with increasing pressure. The temperature region of the cubic phase of ANBC-20 becomes narrower with increasing pressure and a triple point for the SmC, Cub and I phases is estimated to be at about 309 MPa. On the other hand, the cubic phase of ANBC-22 is still observed at the highest pressure examined.     

Effect of sorbed molecules on the resistivity of alkali metal-graphite intercalation compounds

Alkali metal-graphite intercalation compounds with the composition of MC₂₄ (M=K, Rb, Cs) were prepared by heating a mixture of MC₈ (saturated compound) and graphite sheet (Grafoil) at 350-450 °C. The resistivity perpendicular to the layer planes (ρ_c) of the resulting compounds was determined by the two-terminal method. The anisotropy factor of the resistivity, (ρ_c/ρ_a), of KC₂₄ prepared from Grafoil was ∼130, being about 1/6-1/10 in magnitude compared with that of KC₂₄ prepared from highly oriented pyrolytic graphite. The resistivity change during sorption of hydrogen (at 90 K), ethylene (at 194 K) and acetylene (at 194 K) was determined. The resistivity of MC₂₄ increased with increase of the sorbed amount of H₂. The magnitude of the increase was in the order KC₂₄>RbC₂₄>CsC₂₄. This resistivity increase was considered to be due to the expansion along c-direction which reduces the charge-transfer interaction between the carbon layers and potassium ions, resulting in the decrease of the density of the conduction electron. The resistivity of MC₂₄ increased extensively during sorption of C₂H₄ and C₂H₂. It was discussed in connection with the in-plane structural transition and chemical interaction between alkali metal ions and sorbed molecules.