Reaction of thioketones with propiolic acids

The reaction of adamantane-2-thione with propiolic acid afforded a novel type of cycloadduct, spiro[adamantane-2,2'-6'H-[1,3]-oxathiin]-6'-one (3a), in quantitative yield. The reaction of thiobenzophenone with propiolic acid gave 2,2-diphenyl-6'H-[1,3]-oxathiin]-6'-one and 4-phenyl-3-thia-3,4-dihydronaphthoic acid in 34% and 35% yields, respectively. The reaction might proceed through a concerted process, as confirmed by kinetics. The reaction of adamantane-2-thione with 2-butynoic acid or phenylpropiolic acid gave the corresponding adducts regioselectively. Interestingly, only one isomer was obtained by the reaction of thiofenchone with propiolic acid, suggesting that the reaction proceeded diastereospecifically. Oxidation of adducts by dimethyldioxirane or m-chloroperoxybenzoic acid gave the corresponding sulfoxides and sulfones. The sulfoxides were thermally decomposed to give disulfide or another type of 1,3-oxathiin-6-one.     

Evaluation of cell-free protein synthesis using PDMS-based microreactor arrays.

A living cell has numerous proteins, only a few thousand of which have been identified to date. Cell-free protein synthesis is a useful and promising technique to discover and produce various proteins that might be beneficial for biotechnological, pharmaceutical, and medical applications. For this study, we evaluated the performance and the general applicability of our previously developed microreactor array chip to cell-free protein synthesis by comparisons with a commercially available system. The microreactor array chip comprises a temperature control chip made of glass and a disposable reaction chamber chip made of polydimethylsiloxane (PDMS). For evaluation of the microreactor array chip, rat adipose-type fatty acid binding protein, glyceraldehyde-3-phosphate dehydrogenase, cyclophilin, and firefly luciferase were synthesized from their respective DNA templates using a cell-free extract prepared from Escherichia coli. All these proteins were synthesized in the microreactor array chip, and their respective amounts and yields were investigated quantitatively.     

Novel Photodynamic Therapy Using Water-dispersed TiO2–Polyethylene Glycol Compound: Evaluation of Antitumor Effect on Glioma Cells and Spheroids In Vitro

Titanium dioxide (TiO₂) is thought to be a photocatalytic agent excited by UV light. Our aim was to investigate the photocatalytic antitumor effect of water-dispersed TiO₂ nanoparticles on C6 rat glioma cells and to evaluate the treatment responses by the spheroid models. Water-dispersed TiO₂ nanoparticles were constructed by the adsorption of chemical modified polyethylene glycol (PEG) on the TiO₂ surface (TiO₂/PEG). Each monolayer and spheroid of C6 cells was coincubated with various concentrations of TiO₂/PEG and subsequently irradiated with UV light. Damage of the cells and spheroids was evaluated sequentially by staining with the fluorescent dyes. The cytotoxic effect was correlated with the concentration of TiO₂/PEG and the energy dose of UV irradiation. More than 90% of cells were killed after 13.5 J cm⁻² of UV irradiation in the presence of 500 μg mL⁻¹ TiO₂/PEG. The irradiated spheroids in the presence of TiO₂/PEG showed growth suppression compared with control groups. In TiO₂/PEG-treated spheroids, the number of Annexin V-FITC-stained cells gradually increased during the first 6 h, and subsequently propidium iodide-stained cells appeared. The results of this study suggest that newly developed photoexcited TiO₂/PEG have antitumoral activity. Photodynamic therapy utilizing this material can be a clue to a novel therapeutic strategy for glioma.     

Thermal conductivity of high strength polyethylene fiber in low temperature

High strength polyethylene fiber (Toyobo, Dyneema® fiber, hereinafter abbreviated to DF) used as reinforcement of fiber‐reinforced plastics for cryogenic use has a high thermal conductivity. To understand the thermal conductivity of DF, the relation between fiber structure and thermal conductivity of several kinds of polyethylene fibers having different modulus from 15 to 134 GPa (hereinafter abbreviated to DFs) was investigated. The mechanical series‐parallel model composed of crystal and amorphous was applied to DFs for thermal conductivity. This mechanical model was obtained by crystallinity and crystal orientation angle measured by solid state NMR and X‐ray. Thermal conductivity of DF in fiber direction was dominated by that of the continuous crystal region. The thermal conductivity of the continuous crystal part estimated by the mechanical model increases from 16 to 900 mw/cmK by the increasing temperature from 10 to 150K, and thermal diffusivity of the continuous crystal part was estimated to about 100 mm²/s, which is almost temperature independent. The phonon mean free path of the continuous crystal region of DF obtained by thermal diffusivity is almost temperature independent and its value about 200 Å. With the aforementioned, the mechanical series‐parallel model composed of crystal and amorphous regions could be applied to DFs for thermal conductivity. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1495–1503, 2005     

Duality and double shuffle relations of multiple zeta values

We prove that certain families of duality relations of the multiple zeta values (MZV's) are consequences of the extended double shuffle relations (EDSR's), thereby proving a part of the conjecture that the EDSR's give all linear relations of the MZV's.     

Absorption and fluorescence spectra of 9-anthrol and its chemical species in solution

The absorption, fluorescence, and fluorescence-excitation spectra of 9-anthrol (and/or anthrone) have been observed in various solvents, one of which includes a silicon-aluminium ester (diisobutoxyaluminium triethyl silane[(OBu)₂−Al−O−Si−(OEt)₃ SAE]). The fluorescence spectra of 9-anthrol shows peak wavelengths at 442 nm in benzene, 454 nm in methanol, 539 nm in triethylamine, and 550 nm in basic solution, which can be assigned to a neutral, a hydrogen-bonded neutral, an ion pair, and an anionic species of 9-anthrol, respectively. In ethanol solution including SAE, on the other hand, a new fluorescence peak appears at 473 nm. This new band originates from a complex formed between 9-anthrol and SAE. The excited-state ion pair is formed through the hydrogen-bonded form in water and the complex form in triethylamine. CNDO/S calculations support the experimental results.     

Drying dissipative structures of cationic gel spheres of lightly cross-linked poly(2-vinylpyridine) in deionized aqueous suspension

Drying dissipative patterns of cationic gel crystals of lightly cross-linked poly(2-vinylpyridine) spheres (CAIBA-P2VP(0.1), CAIBA-P2VP(0.5), and CAIBA-P2VP(1), 107?~?113 nm in diameter and 0.1, 0.5, and 1 in degrees of cross-linking) were observed on a cover glass, a watch glass, and a Petri glass dish. Convectional spoke line and cluster patterns were recognized with the naked eyes, which supports that these poly(2-vinylpyridine) gel spheres aggregate temporarily and reversibly during the course of drying. Two kinds of broad rings were observed at the outside edge and inner region in the macroscopic drying pattern. The size of the inner rings decreased with gel concentration. Formation of similar-sized aggregates (or agglomerates) and their ordered arrays ((a) ordered ring, (b) spoke lines, (c) net structures, and (d) lattice structures) were observed, though the arrays were not so complete compared with those of large-sized analogous gel spheres. One of the main causes of the incomplete ordering of the aggregates is the rather high polydispersities in the sphere size. The ordering of similar-sized aggregates is common among the gel spheres including anionic poly(N-isopropylacrylamide) and cationic poly(2-vinylpyridine). Size effect of cationic gel spheres on the ordering of the agglomerates was clarified definitely in this work. The role of the convectional flow and the electrical double layers around the agglomerates and their interaction with the substrates during drying was also clarified to be very important for the drying pattern formation.     

Synthetic Molecules that Protect Cells from Anoikis and Their Use in Cell Transplantation

One of the major problems encountered in cell transplantation is the low level of survival of transplanted cells due to detachment‐induced apoptosis, called anoikis. The present study reports on the chemical synthesis and biological evaluation of water‐soluble molecules that protect suspended cells from anoikis. The synthetic molecules bind to and induce clusters of integrins and heparan‐sulfate‐bound syndecans, two classes of receptors that are important for extracellular matrix‐mediated cell survival. Molecular biological analysis indicates that such molecules prolong the survival of suspended NIH3T3 cells, at least in part, by promoting clustering of syndecan‐4 and integrin β1 on the cell surface, leading to the activation of small GTPase Rac‐1 and Akt. In vivo experiments using animal disease models demonstrated the ability of the molecules to improve cell engraftment. The cluster‐inducing molecules may provide a starting point for the design of new synthetic tools for cell‐based therapy.     

Polymerization of Olefins by a Ziegler Catalyst Supported on Poly(ethylene-co-Vinyl Alcohol)

The polymerization and catalytic behavior of a Ziegler type catalyst supported on poly(ethylene-co-vinyl alcohol) (EVA) were investigated. The rate of ethylene polymerization by a catalyst prepared from titanium tetrachloride supported on EVA (vinyl alcohol 18 mole %) and triethylaluminum (AlEt₃) is much higher than that of an n-butoxytitanium trichloride (BTT)-AlEt3 catalyst. The polymer-supported catalyst has prolonged high activity during polymerization compared with the BTT-AlEt₃ catalyst. The stabilization of the catalyst seems to depend on its slower reduction by alkylaluminum compounds, due to steric hindrance by bulky polymer ligands. Polypropylene prepared by the polymer supported Ziegler catalyst is essentially atactic, and it differs little from that prepared with a BTT-AlEt₃ catalyst. Vinyl chloride was also polymerized by this catalyst. The catalytic activity was, however, very small.