Polymer complex from copolymers of acrylonitrile and ionic vinyl benzyl compounds

Copolymerization of sodium vinyl benzyl sulfonate (VBS) or vinyl benzyl trimethyl ammonium chloride (VBQ) with acrylonitrile (AN) gave polyelectrolytes of preferable solution viscosities. The blending of these two copolymers in N,N-dimethyl formamide (DMF) produced polymer complexes with ionic linkages, of which the following properties were examined. The maximum in the tan δ temperature was increased by complex formation. Freundlich-type dye adsorption and much better dyeability than on polyacrylonitrile was observed. Electric resistivity decreased with the introduction of ionic moiety. Permeability of water increased with the number of ionic sites. Homogeneous films could be cast from DMF and dimethyl sulfoxide (DMSO) solutions.     

The constitutive creep equation for a eutectic Sn-Ag alloy using the modified theta-projection concept

Creep data for a eutectic tin-silver alloy at temperatures between 298 K and 398 K have been analyzed using the modified theta-projection concept, instead of the steady-state creep constitutive equation in the following formula: ɛ_cr=A {1−exp(−αt)}+B {exp(αt)−1}, where A, B, and α are constants to be experimentally determined. The equation describes well the creep curves of the eutectic tin-silver alloy up to the tertiary stage. All constants exhibited power law relationships with the applied stress. The rate constant, α, has a high stress exponent, which is attributed to dispersion strengthening. The rate constant a and the strain factor B only showed temperature dependence, while the strain factor A was independent of temperature. The activation energy for α was 65 kJ/mol at high stresses and 90 kJ/mol at low stresses. The energies suggest that the dislocation pipe diffusion and the lattice diffusion are predominant at high stresses and low stresses, respectively.     

Heavy metal ion scavengers from cyanuric chloride

Cyanuric chloride was reacted with polyamines and thiourea, and subsequent hydrolysis of the isothiouronium salt yielded amine polymers with divalent sulfur. The polymers scavenge cupric, cadmium, lead, and mercuric ions from considerably concentrated hydrogen chloride solutions, and they were compared with polystyrene—sulfonic acid resin. Zinc, cobaltous, and nickel ions are adsorbed only at relatively high pH (4.8–6.8). Removal of cupric, cadmium, and mercuric ions is not affected by the addition of sodium chloride.     

An experimental study of fatigue resistance in epoxy injection for cracked mortar and concrete considering the temperature effect

The effect of temperature on fatigue resistance in repaired mortar and concrete members through epoxy injection is experimentally studied. First, fatigue equipment capable of inducing a small movement is developed to simulate cracks, which are monitored in a real wall structure. The fatigue test is performed considering three different levels of movement amplitude and four different levels of temperature by using fatigue equipment. From the fatigue test, increases in amplitudes and temperature cause reduced resistance to fatigue.Furthermore, the effect of temperature on the failure mode of epoxy-repaired mortar is evaluated. With higher temperature, the failure mode is changed from mortar failure to mixed failure of epoxy and interface. Then, in the mixed failure mode, resistance to fatigue significantly decreases owing to the temperature effect.     

Inhibitory effects of acidic xylooligosaccharide on stress-induced gastric inflammation in mice

The preventive effects of acidic xylooligosaccharide prepared from xylan of corncobs and related sugars on stress-induced gastric inflammation in mice were investigated. Oral administration of acidic xylooligosaccharide and hydrocortisone at doses of 100 and 200 mg/kg body weight significantly reduced the number of bleeding points in the gastric mucosa of mice loaded with cold-restraint stress. Acidic xylooligosaccharide showed concentration-dependent superoxide anion radical-scavenging activity at concentrations of 3.3-4.3 mg/mL and its IC50 was 3.5 mg/mL, although this value is approximately six times that of quercetin. The antioxidant activity of acidic xylooligosaccharide could contribute, in part, to its suppressive activities on stress-induced mouse gastritis. Xylose, xylobiose, xylan, and glucuronic acid showed no significant suppressive activities on mouse gastric inflammation at a dose of 100 mg/kg body weight. These results suggest that an appropriate degree of polymerization of xylan (larger than trimer) is necessary for the activities of acidic xylooligosaccharide.