Efficient Chemoselective Oxidation of Phenylmethanols to Aldehydes with Iodosobenzene

Summary. Primary phenylmethanols are selectively and efficiently oxidized to the corresponding aldehydes by the system C₆H₅IO/(C₆H₅)₄PBr/CH₂Cl₂, T = 298 K under aerobic conditions. The use of the relatively stable iodosobenzene, an iodine(III) compound, in place of the usually employed and potentially explosive iodine(V) reagents, the easy work-up procedure, and the facile recycling of solvent and oxidant provides a convenient and environmentally benign oxidation method.     

A proposal for a convertible stadium roof structure derived from Watt-I linkage

In this paper, a novel convertible stadium roof structure is introduced, which has been derived from a special geometric configuration of Watt-I linkage, a 1-DoF mechanism used in robot technologies as anthropomorphic fingers. The proposed structure can offer a wide range of different shape configurations according to the environmental conditions and spatial needs, thus offering several aesthetic and functional advantages over existing solutions. This paper serves as a feasibility investigation of this concept, mainly from geometric and structural point of view. To that affect, first kinematic analysis and geometric design of this linkage are introduced. Then, structural analyses of the proposed structure with realistic dimensions and loading conditions are performed in three different geometric configurations, in order to discuss strength and stiffness limitations. Finally, potential cover materials and actuators are briefly discussed.     

A High Cell‐Bearing Capacity Multibore Hollow Fiber Device for Macroencapsulation of Islets of Langerhans

Macroencapsulation of islets of Langerhans is a promising strategy for transplantation of insulin‐producing cells in the absence of immunosuppression to treat type 1 diabetes. Hollow fiber membranes are of interest there because they offer a large surface‐to‐volume ratio and can potentially be retrieved or refilled. However, current available fibers have limitations in exchange of nutrients, oxygen, and delivery of insulin potentially impacting graft survival. Here, multibore hollow fibers for islets encapsulation are designed and tested. They consist of seven bores and are prepared using nondegradable polymers with high mechanical stability and low cell adhesion properties. Human islets encapsulated there have a glucose induced insulin response (GIIS) similar to nonencapsulated islets. During 7 d of cell culture in vitro, the GIIS increases with graded doses of islets demonstrating the suitability of the microenvironment for islet survival. Moreover, first implantation studies in mice demonstrate device material biocompatibility with minimal tissue responses. Besides, formation of new blood vessels close to the implanted device is observed, an important requirement for maintaining islet viability and fast exchange of glucose and insulin. The results indicate that the developed fibers have high islet bearing capacity and can potentially be applied for a clinically applicable bioartificial pancreas.     

Polymer conformation in mixed aqueous-polar organic solvents

The conformation of the common polysaccharide dextran has been investigated in mixed solvents at two different temperatures using viscosity measurements. In particular we considered binary mixtures of water with the polar organic solvents glycerol, formamide, dimethylsulfoxide, or ethanol. The intrinsic viscosity of dextran T500 in the different systems has been determined, and the solvent effects, as manifested in variations of the dextran intrinsic viscosity and coil radius, have been correlated to the surface tension and the fractional solubility parameters of the solvent mixture. The coil dimension changes observed in the different solvent mixtures are consistent with expectations from water-cosolvent-dextran interactions, especially as they pertain to hydrogen bonding.     

Thermal Drying of <Emphasis Type="BoldItalic">Lactobacillus delbrueckii</Emphasis> subsp. <Emphasis Type="BoldItalic">bulgaricus</Emphasis> and its Efficient Use as Starter for Whey Fermentation and Unsalted Cheese Making

Lactobacillus bulgaricus grown on whey was dried by a simple thermal drying method at the range 35–55°C and its efficiency for lactic acid fermentation of whey was evaluated. Drying of cells in whey suspension in the examined temperature range did not affect significantly their viability (82–87% survival), indicating a protective effect of whey as both growth and drying medium. The kinetics of fermentation of whey and mixtures of whey/molasses using the dried culture were comparable to those of non-dried cells, and only low pH had a detrimental effect on the fermentation ability of the dried cells. Furthermore, dried L. bulgaricus, free or immobilized on casein coagulates, was used as starter for the production of unsalted hard-type cheese. The effects of the amount of starter culture and the immobilization technique, the evolution of microbial counts, and the sensory properties of the produced cheeses were evaluated during ripening at various temperatures.     

Special issue of FOA10 in honor of our colleagues in Japan and New Zealand

Tribute

Special issue of FOA10 in honor of our colleagues in Japan and New Zealand     

Über die Tribromomangan(II)-Säure und deren Komplex mit Pyridin

Tribromomanganese(II) acid has been prepared for the first time and will be described. A complex of the acid with pyridine was obtained and its UV, visible, IR and¹H-NMR spectra will be reported.     

Rapid genotyping of CYP2D6, CYP2C19 and TPMT polymorphisms by primer extension reaction in a dipstick format

In recent years an increasing amount of interest has been directed at the study and routine testing of polymorphisms responsible for variations in drug metabolism. Most of the current methods involve either time-consuming electrophoresis steps or specialized and expensive equipment. In this context, we have developed a rapid, simple and robust method for genotyping of CYP2D6*3, CYP2D6*4, CYP2C19*2, CYP2C19*3 and TPMT*2 single nucleotide polymorphisms (SNP). Genomic DNA is isolated from whole blood and the segments that span the SNP of interest are amplified by PCR. The products are subjected directly (without purification) to two primer extension (PEXT) reactions (three cycles each) using normal and mutant primers in the presence of biotin-dUTP. The PEXT primers contain a (dA)₃₀ segment at the 5′ end. The PEXT products are detected visually by a dry-reagent dipstick-type assay in which the biotinylated extension products are captured from immobilized streptavidin on the test zone of the strip and detected by hybridization with oligo(dT)-functionalized gold nanoparticles. Patient samples (76 variants in total) were genotyped and the results were fully concordant with those obtained by direct DNA sequencing.     

Metallocene-mediated cationic polymerization of vinyl ethers: Kinetics of polymerization and synthesis and characterization of statistical copolymers

The cationic polymerization of ethyl, n-butyl and iso-butyl vinyl ether, EVE, BVE and iBVE, respectively, was efficiently conducted using bis(η⁵-cyclopentadienyl)dimethyl hafnium, Cp₂HfMe₂, or bis(η⁵-cyclopentadienyl)dimethyl zirconium, Cp₂ZrMe₂ in combination with either tris(pentafluorophenyl)borate, B(C₆F₅)₃, or tetrakis(pentafluorophenyl)borate dimethylanilinum salt, [B(C₆F₅)₄]^?[Me₂NHPh]⁺, as initiation systems. The evolution of polymer yield, molecular weight and molecular weight distribution with time was examined. In addition, the influence of the initiating system, the monomer and the reaction conditions on the control of the polymerization was studied. Furthermore, statistical copolymers of EVE with BVE were prepared employing Cp₂HfMe₂ and [B(C₆F₅)₄]^?[Me₂NHPh]⁺ as the initiation system. The reactivity ratios were estimated using both linear graphical and non-linear methods. Structural parameters of the copolymers were obtained by calculating the dyad sequence fractions and the mean sequence length, which were derived using the monomer reactivity ratios. The glass transition temperatures, Tg, of the copolymers were measured by Differential Scanning Calorimetry, DSC, and the results were compared with predictions based on several theoretical models. The kinetics of thermal decomposition of the copolymers along with the respective homopolymers was studied by thermogravimetric analysis within the framework of the Ozawa-Flynn-Wall and Kissinger methodologies.     

Structural characterization of the smectic polymorphism of chiral liquid crystalline polysiloxanes containing biphenyl mesogens

A structural characterization of chiral side chain siloxanes with different average degrees of polymerization, DP_n, was performed by X-ray diffraction experiments on powder and oriented fibre specimens. Polymers (DP_n = 35) and oligomers (DP_n = 4) contained the 4,4'-biphenylene unit with either an (S)-2-methylbutoxy (An, Bn) or an (S)-2-chloro-3-methylbutanoyloxy substituent (Cll). The spacer segment connected to the siloxane backbone had a variable number, n, of methylene groups (n = 5, 8, or 11). Independent of the spacer length and the chiral tail nature, the polysiloxanes underwent the same sequence of phases: C-S_F1 (or S_I1)-S_C1-S_A1-I, whereas in the oligosiloxanes the sequence C-S_B1-S_A1-I (B11) or C-S_F1-S_C1-I (B5) occurred. The influence of the structure of the polysiloxanes on the formation of the smectic (tilted or orthogonal) mesophases was elucidated. The rather large number of reflections (three or four) detected in the X-ray patterns at low angles, allowed a drawing of the projection of the electron density profiles along the layer normal, p(z), and deduction of the most physically acceptable electron density profiles from among the numerous possibilities for each smectic phase. The electron density profiles were in agreement with monolayer smectic phases presenting a microphase separation between the siloxane backbones and the side chains, so constraining the polymer backbones within a thin layer.