Hydrolytic Degradation of Aliphatic Polyesters Copolymerized with Poly(ethylene glycol)s

Poly(1,4-butanediol succinate) copolymers were prepared by melt polycondensation of succinic acid and 1,4-butanediol with 10–50mol% (in feed) of poly(ethylene glycol) (PEG), where molecular weight (MW) of PEG is 200–2000. The reduced specific viscosity of the copolymers increased with incorporation of the PEG component, but a higher PEG content in the copolymers reduced it. The temperature of melting (T_m) and crystallinity decreased with increasing PEG content. T_m depression of the copolymers followed approximately Flory’s equation, suggesting that these are random type copolymers. Tensile strength and elongation decreased with increasing MW and content of PEG. The weight loss of copolymer films in a buffer solution with or without lipase at 37°C, as well as water absorption, increased with increasing PEG content, implying that higher water absorption contributes to hydrolytic degradation of the films. However, the weight loss of copolymers with PEG of lower MW increased greatly in spite of lower water absorption, demonstrating that hydrolytic degradation is influenced by the concentration of degradable ester linkages between succinic acid and PEG segments rather than water absorption. © of SCI.     

Diabetes-induced and age-related changes in fatty acid proportions of plasma lipids in rats

Diabetes-induced and age-related proportional changes in plasma fatty acids of triglycerides (TG), phospholipids (PL), and cholesteryl esters (CE) were investigated using streptozotocin-induced diabetic and control rats. Among n-6 fatty acids from diabetic rat plasma, increased proportions of 18∶2n-6 and 20∶3n-6 in all three lipid classes and of 18∶3n-6 in PL at 1–3 months old and in TG at 3–5 months old were observed. The proportions of 20∶4n-6 decreased in both PL and CE, but were unchanged in diabetic TG. Among the n-3 fatty acids, in the early stage, diabetes caused increases in the proportions of 18∶3n-3 in PL and CE and of 20∶5n-3 and 22∶6n-3 in TG, while 22∶5n-3 was decreased later in the disease course. These results suggest reduced Δ5-desaturase activities on 20∶3n-6 but not on 20∶4n-3, while Δ6-desaturase activity on 18∶2n-6 was essentially unaffected. Furthermore, the reduction in Δ9-desaturase activity in diabetic rats may well explain the decreases in the proportions of 16∶1n-7 and 18∶1n-7. However, the proportion of 18∶1n-9, another product of Δ9-desaturase, was significantly increased in CE and PL as compared to the controls. Thus, there was a discrepancy between our results and those of earlier studies with respect to the n-9, n-6, and n-3 fatty acid proportions of plasma lipids in diabetic rats. We also investigated age-related changes in the proportions of plasma fatty acids. Although rather small, age-related changes were evident in both diabetic and control rats.     

Stable equilibrium shift of methane steam reforming in membrane reactors with hydrogen‐selective silica membranes

Equilibrium shifts of methane steam reforming in membrane reactors consisting of either tetramethoxysilane‐derived amorphous hydrogen‐selective silica membrane and rhodium catalysts, or hexamethyldisiloxane‐derived membrane and nickel catalysts is experimentally demonstrated. The hexamethyldisiloxane‐derived silica membrane showed stable permeance as high as 8 × 10^?8 mol m^?2 s^?1 Pa^?1 of H₂ after exposure to 76 kPa of vapor pressure at 773 K for 60 h, which was a much better performance than that from the tetramethoxysilane‐derived silica membrane. Furthermore, the better silica membrane also maintained selectivity of H₂/N₂ as high as 10³ under the above hydrothermal conditions. The degree of the equilibrium shifts under various feedrate and pressure conditions coincided with the order of H₂ permeance. In addition, the equilibrium shift of methane steam reforming was stable for 30 h with an S/C ratio of 2.5 at 773 K using a membrane reactor integrated with hexamethyldisiloxane‐derived membrane and nickel catalyst. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Synthesis of poly(1,4-naphthylene) bearing crown ether side chain by asymmetric oxidative coupling polymerization

The oxidative coupling polymerization of racemic-, (R)-, and (S)-2,2′,3,3′-tetrahydroxy-1,1′-binaphthyl derivatives bearing a crown ether moiety was carried out in the presence of a Cu(I) or Cu(II) catalyst with various ligands, such as N,N,N′,N′-tetramethylethylenediamine, (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine, (−)-sparteine [(−)Sp], and (S)-(−)-2,2′-isopropylidenebis(4-phenyl-2-oxazoline). Methanol-insoluble poly(binaphthyl crown ether) with a molecular weight up to M_n=4.1×10³ was synthesized in moderate yields. Polymerization using (−)Sp proceeded in an S-selective manner; the polymer with the highest negative specific rotation was obtained with the (S)-monomer. The obtained polymers exhibited characteristic abilities for chiral recognition toward amino acids, such as 2-phenylglycine hydrochloride and 2-phenylglycine methyl ester hydrochloride.     

Thrombin Receptor-Activating Protein (TRAP)-Activated Akt Is Involved in the Release of Phosphorylated-HSP27 (HSPB1) from Platelets in DM Patients

It is generally known that heat shock protein 27 (HSP27) is phosphorylated through p38 mitogen-activated protein (MAP) kinase. We have previously reported that HSP27 is released from human platelets associated with collagen-induced phosphorylation. In the present study, we conducted an investigation into the effect of thrombin receptor-activating protein (TRAP) on the release of HSP27 in platelets in type 2 diabetes mellitus (DM) patients. The phosphorylated-HSP27 levels induced by TRAP were directly proportional to the aggregation of platelets. The levels of phosphorylated-HSP27 (Ser-78) were correlated with the levels of phosphorylated-p38 MAP kinase and phosphorylated-Akt in the platelets stimulated by 10 µM TRAP but not with those of phosphorylated-p44/p42 MAP kinase. The levels of HSP27 released from the TRAP (10 µM)-stimulated platelets were correlated with the levels of phosphorylated-HSP27 in the platelets. The released platelet-derived growth factor-AB (PDGF-AB) levels were in parallel with the HSP27 levels released from the platelets stimulated by 10 µM TRAP. Although the area under the curve (AUC) of small aggregates (9–25 µm) induced by 10 µM TRAP showed no significant correlation with the released HSP27 levels, AUC of medium aggregates (25–50 µm), large aggregates (50–70 µm) and light transmittance were significantly correlated with the released HSP27 levels. TRAP-induced phosphorylation of HSP27 was truly suppressed by deguelin, an inhibitor of Akt, in the platelets from a healthy subject. These results strongly suggest that TRAP-induced activation of Akt in addition to p38 MAP kinase positively regulates the release of phosphorylated-HSP27 from human platelets, which is closely related to the platelet hyper-aggregation in type 2 DM patients.     

Synthesis and properties of novel vinyl polymers bearing azacrown ether side chain

Summary Novel vinyl polymers bearing monoazacrown ether-type side chains with a number average molecular weigh of over 5000 were radically synthesized from the 16-membered α-methylenemacrolide monomers. The obtained polymers possessed a Na⁺ or K⁺ selective extraction ability, whereas K⁺ was preferentially extracted by the monomers. The polymer having the N-(2-naphthoyl)azacrown ether pendant groups showed a selective UV-responsive complexation with Li⁺ in 1,2-dichloroethane-CH₃CN.     

Synthesis of Superconducting 2212 Phase in the Bi–Pb–Sr–La–Cu–O System

There have been no report about synthesis of the Bi-2212 compound in the Bi–r–La–Cu–O system. We have succeeded in synthesizing the Bi-2212 compound by partial substitution of Pb for Sr and/or Bi in the Bi–Sr–La–Cu–O system. Two samples of nearly the single 2212 phase have been obtained at a nominal composition of Bi_1.5Pb_0.5Sr_2.5La_0.5Cu₂O _z . Both of the samples crystallize in a psedotetragonal lattice, and their lattice parameters are a = 0.5476 nm and c = 3.085 nm or a = 0.5479 nm and c = 3.055 nm. They are both superconductors. The sample with longer lattice parameter c shows an onset of the resistivity drop and zero resistivity at higher temperatures of about 40 K and about 13 K, respectively. This sample also shows a diamagnetic signal starting at about 35 K with lowering temperature.     

A 0.5 V single power supply operated high-speed boosted andoffset-grounded data storage (BOGS) SRAM cell architecture

This paper proposes a 0.5 V/100 MHz/sub-5 mW-operated 1-Mbit SRAM cell architecture which uses a boosted and offset-grounded data storage (BOGS) scheme. The key target of BOGS is to minimize the charge amount supplied from the embedded charge pump circuits, which are required to boost the effective gate to source voltage (V₀=V_GS-V_T) up to 0.8 V necessary to achieve 100 MHz operation even at 0.5 V single power supply. Thus, the key low-power strategy of BOGS is “putting the right (higher efficiency) boosted power-supply from charge pump circuit into the right position (less power consumed transistor) in a SRAM cell.” This paper is focused on why BOGS can realize a greater savings of the charge amount supplied from the boosted power-line and can reduce the power dissipation to ⩽1/30.4 and ⩽1/3.9 compared to the previously reported negative source-line drive (NSD) scheme and negative word-line drive (NWD) scheme, respectively, while achieving a 0.5 V/100 MHz operation     

A compact micro-beam system using a tapered glass capillary for proton-induced X-ray radiography

A compact micro-beam system, containing a tapered glass capillary tube with a tip diameter on the order of 10 μm, was constructed to examine the applicability of capillary-generated micro-beams to high-contrast radiography based on proton-induced quasi-monochromatic X-rays. The transport efficiency of swift protons (2-3 MeV) through the capillary was examined as a function of the capillary tilt angle and the capillary tip diameter. We obtained transport efficiencies of approximately three times larger than would be expected from the geometrical shape of the capillary. This enhancement indicates that a focusing effect occurred in the capillary. A metallic thin foil was irradiated with the micro-beam and quasi-monochromatic X-rays were produced. By calculating the X-ray yields induced by proton bombardment in the foil and comparing them with the X-ray counts observed at the detector, the throughput efficiency of the X-ray imaging system was evaluated. We demonstrated magnification radiography of a small object to show that a spatial resolution on the order of 10 μm was achievable in our system.     

Heat Shock-Induced Three-Dimensional-Like Proliferation of Normal Human Fibroblasts Mediated by Pressed Silk

The aim of this study was to determine the optimal heat treatment conditions for enhancement of pressed silk-mediated 3D-like proliferation of normal human dermal fibroblasts, as well as to determine the responses to heat shock of cells and intracellular signaling pathways. The beginning of 3D-like pattern formation of cells was observed in the second week after the start of the experiment. The mean rates of beginning of 3D-like pattern formation by cells heat-treated at 40 ºC and 43 ºC for 10 min were significantly higher (3.2- and 8.6-fold, respectively) than that of untreated cells. We found that apoptosis had occurred in 7.5% and 50.0% of the cells at one week after heat treatment for 10 min at 43 ºC and 45 ºC, respectively. Western blot analysis demonstrated that phosphorylation of p38 MAPK and that of Hsp27 were markedly increased by heat treatment at 43 ºC for 10 min. The results of an experiment using a p38 MAPK inhibitor and Hsp27 inhibitor suggest that activation of p38 MAPK by heat shock is associated with 3D-like cell proliferation and that Hsp27 contributes to the inhibition of apoptosis. The results of this study should be useful for further studies aimed at elucidation of the physiologic mechanisms underlying thermotherapy.