Improvement of poly(vinyl alcohol)/poly(vinylpyrrolidone) blended hydrogel by radiation crosslinking

1IntroductionHydrogelisapolymericmaterial(syntheticornaturaJ)whichswellswhenplacedincontactwithwaterbutisnotsolubleandhastheabililtytoretainwaterwithinitsstructare.InIecentyears,muchattentionhasbeenfocusedontheresearchanddevelopmentofthepolymerhydIogelsforbiomaterials,suchascontactlenses,wounddressing,enzymeimmunoassay,cathetersanddIugdeliverysystems[1~3].Adressingisoftencoveredonthewotmdtoaccelerateitshealing.TheIearetwokindsofdiessings:drytypeandwettype.Ithasbeenreportedthatheallngwithawe…     

Driving simulator experiment on the moving stability of an automobile under strong crosswind

In expanding expressway networks in Japan, various types of structures have been constructed, e.g., long span bridges and bridges with high piers. The expressway structures are well designed for the external dynamic forces, e.g., earthquakes and strong winds. However, for further safety promotion of the expressway networks, it is important to evaluate the drivers’ responses under strong dynamic disturbances. The present authors have investigated the moving stability of a vehicle under seismic motion based on both numerical simulation and virtual experiments using a driving simulator. Strong crosswind is considered as another factor that makes it difficult for drivers to control their vehicles. This study investigates the moving stability of a vehicle under strong crosswind based on numerical analyses and driving simulator experiments. To predict the future position of a moving vehicle including the reaction of a driver, the second-order predictable correction model is used in the numerical analyses. The results obtained from the numerical and experimental studies are compared and the validity of the driver model is discussed. It is expected that this research is helpful for the decision-making of expressway closure under strong wind and the design of wind barriers.     

The beta adrenoreceptor antagonist, nipradilol, preserves the endothelial nitric oxide response in atherosclerotic vessels of rabbit

We evaluated the effects of nipradilol, a beta-adrenoreceptor antagonist which contains a nitroxy residue, for vascular response in atherosclerosis of rabbits. Four groups of rabbits received different diets (standard diet; standard diet plus 10 mg/kg/day nipradilol; atherogenic diet [standard diet plus 1% cholesterol]; atherogenic diet plus 10 mg/kg/day nipradilol) for 9 weeks. Plasma lipids, blood pressure, vascular function, nitric oxide (NO), activity of NO synthase, cGMP, and histological atherosclerotic changes were evaluated. Neither the atherogenic diet nor nipradilol treatment affected significantly the animals' body weight, blood pressure, or heart rate. The atherogenic diet increased total cholesterol and triglycerides, which were not altered by nipradilol. The atherogenic diet diminished the acetylcholine-induced NO mediated relaxation. Nipradilol treatment restored this relaxation. Analyses using a NO-sensitive selective electrode showed that nipradilol released NO in the presence of cells and that NO release was greater in atherosclerotic aorta with than without nipradilol treatment. Nipradilol treatment increased the basal NO release as evaluated by the aortic tissue cyclic GMP (cGMP) levels in atherosclerotic vessel, and reduced the esterified cholesterol levels in atherosclerotic vessel. Conclusively, NO released by nipradilol may protect endothelium derived relaxation in atherosclerotic vessels, and may partially inhibit the accumulation of cholesterol in the atherosclerotic lesions.     

Preparation of meixnerite (Mg–Al–OH) type layered double hydroxide by a mechanochemical route

We have attempted to synthesize the meixnerite (Mg–Al–OH) type layered double hydroxide (LDH) by a two step milling operation of a mixture of Mg(OH)₂ and Al(OH)₃ with water. In the first-step, a mixture of the starting materials was milled for 1 h without water, and the product prepared in the first-step was milled for 2 h with water in the second-step milling operation. The milled products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and thermo gravimetric-differential thermal analyses with mass spectroscopy (TG-DTA/MS). The surface morphology was characterized by scanning electron microscopy (SEM). Meixnerite with a small amount of carbonate was successfully synthesized mechanochemically at ambient conditions by milling for only 3 h in a planetary ball mill.     

Determination of optimal sending voltage profile in distribution systems with distributed generators

Sending voltage profile of distribution feeder is controlled by changing a tap of distribution transformer. In a distribution network with distributed generators, for reasons of effect of reversed flows from them and existence of a great number of sending voltage profile candidates, it is not easy to control sending voltage profile within the acceptable voltage limit. In this paper, in order to determine the optical sending voltage profile of distribution transformer in a distribution network with distributed generators, the authors propose a new method to determine the optimal sending voltage profile so as to minimize the total number of tap position's change per day under constraints of acceptable voltage limit. In the proposed method, after calculating acceptable range of three‐phase voltage of distribution feeder, the optimal profile of tap position within the calculated acceptable voltage range is determined among these candidates by using reduced ordered binary decision diagram (ROBDD) which is an efficient enumeration algorithm. In order to check the validity of the proposed method, numerical simulations are carried out for a distribution network model with a distributed generator. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(2): 16–24, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20393     

Thermoplastic elastomer by radiation grafting. I. Evaluation of processability of natural rubber grafted methyl methacrylate

Processability of thermoplastic elastomer (TPE) prepared by radiation-induced grafting of methyl methacrylate (MMA) onto radiation vulcanized natural rubber latex (RVNRL) has been evaluated using a kneader and a hot roll mill at 150°C. It was found that mixing time and revolution rate (rpm) of the kneader have significantly affected the processability. The longer mixing time and the higher revolution rate result in better processability. In such processing conditions, however, the mechanical properties were found to be inferior because the molecular chain scissions occurred during the mixing. A considerable improvement of mechanical properties was obtained when the mixing was carried out without added process oils. Blends of the grafted vulcanized natural rubber latex (RVNRL-g-PMMA) and MMA grafted on unvulcanized natural rubber latex (NRL-g-PMMA) improved processability where the better processability could be achieved at a shorter mixing time and a lower revolution rate. In addition, a comparable value of mechanical properties was obtained.     

Evaporation processes of water molecules from graphene edge: DFT and MD study

The evaporation processes of water molecules adsorbed in the edge region of graphene have been investigated by means of direct MO–MD method. A large system composed of 29 water molecules and a graphene sheet (C₉₆H₂₄) was used as a model system. The edge carbon atom of graphene was terminated by hydrogen atom. The geometry optimization showed that the water molecules interact with the hydrogen atoms in the edge region of graphene. At low temperature (300 K), the water molecules were dissociated as water clusters from the graphene. On the other hand, in addition to the dissociation of water clusters, the isolated water molecule was also found as dissociation product at high temperature (500 K). The mechanism of water evaporation was discussed on the basis of theoretical results.     

PCR-RFLP identification of prohibited animal derived DNA in animal feed

A method for confirming identification of prohibited species tissue in animal feed has been developed on the basis of PCR-RFLP analysis. In Japan, to prevent the spread of BSE through animal feed, the use of animal protein in feed has been regulated. Species-specific PCR detection of prohibited species materials in feed has been used as one of a series of laboratory tests to ensure the proper implementation of the feed regulations. However, since the result of this PCR method is determined only by amplicon length, it is sometimes necessary to confirm whether or not the positive result is due to the effect of a non-specific reaction. For this purpose, DNA sequencing is the best way to confirm the test result but it is not suitable for routine analysis because of the required time and cost. In this study, we developed an easy and rapid method to confirm the species identification (mammals, ruminants and cattle) by using 4 restriction enzymes: SmlI, MboI, BlnI and Hpy188III. This PCR-RFLP method, which ensures identification of prohibited animal species in feed, is useful for enhancing the reliability of feed inspection for BSE prevention. This method will be added to the Official Methods of Feed Analysis.