s‐Triazine‐based hyperbranched polyethers: Synthesis,characterization, and properties

A series of s‐triazine‐based hyperbranched polyethers (HBPE) have been synthesized to obtain thermostability but flexible polymers by an interfacial polycondensation of different diols as A₂ and cyanuric chloride as B₃ monomers using A₂ + B₃ approach in the presence of a phase transfer catalyst. The polymerization reaction parameters are optimized, and the results indicate that the optimum conditions for the interfacial polycondensation are a 2:3 mole ratio of cyanuric chloride to diol using butanediol, benzyldimethylhexadecyl ammonium chloride as the catalyst, dichloromethane as the organic solvent, and a three‐step procedure with keeping the reaction mixture at different low temperatures for 2h/2h/5h. Other techniques such as high‐temperature solution, one‐step polycondensation, and transesterification were also carried out to synthesize the HBPE but proved to be not suitable due to large number of side reactions. The synthesized polymers were characterized by FTIR, ¹H NMR, and ¹³C NMR spectroscopy, hydroxyl number determination, solution viscosity measurements, and GPC analysis. The thermal behavior of the hyperbranched polymer was investigated by thermogravimetric analysis and differential scanning calorimetry. All the results were compared with those from an analogous linear polyether, obtained from 2‐methoxy‐4,6‐dichloro‐s‐triazine and butanediol by using the same polymerization technique. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3994–4004, 2010     

Synthesis and characterization of a flame retardant hyperbranched polyether

<正>A brominated hyperbranched polyether has been synthesized from cyanuric chloride and sodium salt of tetrabromobisphenol-A by an A_2+B_3 approach.The synthesized polyether was characterized by ~1H-NMR,~(13)C-NMR,UV, FTIR spectroscopy and X-ray diffraction studies,measurements of solution viscosity,molecular weight and solubility and elemental and thermogravimetric analyses.The flame retardancy of the synthesized polyether and its blends with commercially available plasticized poly(vinyl chloride)(PVC) and low density polyethylene(LDPE) was investigated by measurements of limiting oxygen index(LOI) value and thermogravimetric analysis.The properties are compared with a non-halogenated similar type of bisphenol-A based aromatic polyether after blending at different dose levels with the same base polymers.The LOI values of these blends indicated that these hyperbranched polyethers acted as flame retardant additives,and antimony trioxide had prominent synergistic effect with the bromo hyperbranched polyether for the above base polymers,and an increment of 4 to 6 units in LOI values was observed.     

Short echo time in vivo prostate ¹H-MRSI

Visualization of short echo time (TE) metabolites in prostate magnetic resonance spectroscopic imaging is difficult due to lipid contamination and pulse timing constraints. In this work, we present a modified pulse sequence to permit short echo time (TE=40ms) acquisitions with reduced lipid contamination for the detection of short TE metabolites. The modified pulse sequence employs the conformal voxel MRS (CV-MRS) technique, which automatically optimizes the placement of spatial saturation planes to adapt the excitation volume to the shape of the prostate, thus reducing lipid contamination in prostate magnetic resonance spectroscopic imaging (MRSI). Metabolites were measured and assessed using a modified version of LCModel for analysis of in vivo prostate spectra. We demonstrate the feasibility of acquiring high quality spectra at short TEs, and show the measurement of short TE metabolites, myo-inositol, scyllo-inositol, taurine and glutamine/glutamate for both single and multi-voxel acquisitions. In single voxels experiments, the reduction in TE resulted in 57% improvement in the signal-to-noise ratio (SNR). Additional 3D MRSI experiments comparing short (TE=40 ms), and long (TE=130 ms) TE acquisitions revealed a 35% improvement in the number of adequately fitted metabolite peaks (775 voxels over all subjects). This resulted in a 42 ± 24% relative improvement in the number of voxels with detectable citrate that were well-fitted using LCmodel. In this study, we demonstrate that high quality prostate spectra can be obtained by reducing the TE to 40 ms to detect short T2 metabolites, while maintaining positive signal intensity of the spin-coupled citrate multiplet and managing lipid suppression.     

Eco-friendly heterogeneous solid acids as novel and recyclable catalysts in ionic medium for tetrahydropyranols

A variety of aldehydes and homoallylic alcohols undergo smoothly Prins-cyclization on the surface of solid acids such as H-ZSM-5 zeolite or Amberlyst-15^® ion-exchange resin in 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid to afford the corresponding tetrahydropyranols in high yields with cis-diastereoselectivity. The recovered ionic liquid containing solid acid was recycled in subsequent runs without loss of activity.     

Two new bromotyrosine-derived metabolites from the sponge Psammaplysilla purpurea

Two new bromotyrosine-derived metabolites (1, 2) have been isolated along with the known compounds 3,5-dibromo-4-methoxyphenylacetonitrile, 3-bromo-4-methoxyphenylacetonitrile, 3-bromo-4-hydroxyphenylacetonitrile, 1-hydroxyuracil, 1-methoxyhemibastadin 2, purpuramine H and a steroid 5alpha,8alpha-epidioxycholest-6-en-3beta-ol from the sponge Psammaplysilla purpurea. Compounds 1 and 2 were characterized by interpretation of their spectral data. The antibacterial activity of these compounds is summarized.     

Novel triterpenoid saponins from Mimusops elengi

Two novel triterpenoid saponins, mimusopin ( 3-O-β-D-glucopyranosyl-2β, 3β, 6β, 23-tetrahydroxyolean-12-en-28-oic acid 28-O--L-rhamnopyranosyl-(1→3)-β-D-xylopyranosyl-(1→4)[a-L-rhamnopyranosyl-(1→ 3)]--L-rhamnopyranosyl-(1→2)--L-arabinopyranoside)(1) and mimusopsin 3-O-[β-D-glucopyranosyl-(1→3)β-D-gluco-pyranosyl]-2β, 3β, 6β, 23-tetrahydroxyolean-12-en-28-oic acid 28-O--L-rhamnopyranosyl-(1→3)-β-D-xylopyranosyl-(1→4)--L-rhamnopyranosyl-(1→2)--L-arabinopyranoside (2) were isolated from the seeds of Mimusops elengi. Their structures were elucidated by a combination of 2D-NMR (COSY, HOHAHA, HETCOR, HMBC and NOESY), FAB-MS/MS and strategic chemical degradation. In addition, molecular mechanics and dynamics studies showed that the lack of a ¹³C glycosylation shift at the C-4 of the inner rhamnose in 1 could be correlated with distortion in the corresponding torsion angles.     

KMS states and complex multiplication

We construct a quantum statistical mechanical system which generalizes the Bost–Connes system to imaginary quadratic fields K of arbitrary class number and fully incorporates the explicit class field theory for such fields. This system admits the Dedekind zeta function as partition function and the idèle class group as group of symmetries. The extremal KMS states at zero temperature intertwine this symmetry with the Galois action on the values of the states on the arithmetic subalgebra. The geometric notion underlying the construction is that of commensurability of K-lattices.     

Hydrogen Evolution from L-Lactate and L-Malate with the Combination of Lactate Dehydrogenase or Malate Dehydrogenase and Hydrogenase from A. Eutrophus H16

Hydrogen evolution system from L-lactate and L-malate consisting of lactate dehydrogenase or malate dehydrogenase and hydrogenase from cell free extracts of Alcaligenes eutrophus H16 was established. When the solution containing L-lactate, lactate dehydrogenase, NAD and hydrogenase was incubated at 30°C hydrogen evolution was observed. Similarly, the hydrogen evolution was also observed from the L-malate incubated at 30°C.     

Subfemtomole detection of small molecules with microsphere sensors

We investigated the feasibility of using a silica microsphere sensor for detection of small molecules. Using the silica molecules (60 Da) at the sphere's surface as a model system, we measured the spectral shifts in the whispering-gallery modes (WGMs) when the sphere size was decreased by a hydrofluoric acid (HF) solution. The results demonstrate that our sensor is capable of detecting a 4 pm (or 0.01 layer of silica) decrease in sphere radius, corresponding to a change of 0.4 fmol silica molecule. These results suggest that small molecules can be detected in trace quantities at the surface of an optical microsphere sensor.     

Two diastereomers of 2-[[β-(N-phenylamino)-α-methylphenethyl]-methylamino]-N,N-dimethylacetamide

The structures of two diastereomers ((1R,2R) and (1R,2S)) of the title compound have been determined. The molecular conformation of the (1R,2R) isomer is heavily influenced by strong intramolecular hydrogen bonding between the secondary and tertiary amine groups (N(1)…N(2) 2.629(8) Å; N(4)…N(5) 2.628(8) Å). In the (1R,2S) isomer no intramolecular interaction is observed, but somewhat weaker intermolecular hydrogen bonding does occur between the secondary amine and the carbonyl group of a neighboring molecule (N(1)…O(1) 2.960(6) Å) related by a 2₁ screw operation along thea-axis (x1/40). No close intermolecular contacts are observed for the (1R,2R) isomer. Crystal data for (1R,2R); monoclinic,P2₁ (No. 4),a=18.588(5),b=16.743(4),c=6.062(1) Å, β=97.26(2)^o,V=1871.5(8) A³, Z=4,D _cale=1.16 g/cm³. Crystal data for (1R,2S): orthorhombic,P2₁2₁2₁ (No. 19),a=8.008(2),b=9.985(3),c=23.458(5)Å,V=1875.8(6) ų, Z=4,D _cale=1.15 g/cm³.