Viscoelastic properties of (cellulose oligo-oxymethylene ether) acylates with bulky side chain

A series of (cellulose oligo-oxymethylene ether) acylates (COAs) are characterized by the presence of the micro-Brownian motion of the side chain (β process) which appears separately from that of the main chain (α process). Both the alpha; and β processes are largely affected by the kind of acyl groups introduced in the side chain. To clarify the effect of the acyl group on these processes, we investigated the dynamic mechanical properties of newly prepared COAs with acyl side chain, bulky in chemical structure (iso-butyrate, privalate, and benzoate) in relation to those for COAs with linear acyl side chain (acetate, butyrate, and valerate). By substituting bulky acyl isomer for linear acyl group in COAs, we observed that the temperature region of both the α and β processes moved to higher temperature. Furthermore, with an increase in molecular size of bulky acyl group, the β region shifts were much larger than the α region, indicating that the mobility of the side chain became comparable to that of the main chain. Finally, when such a large bulky group, for example, benzoate was introduced, the micro-Brownian motion of the side chain prior to that of the main chain ceased. The apparent activation energy for a third process (γ) due to the motion of the oligo-oxymethylene parts in the side chain was estimated to be 10.3 kcal/mol.     

Fine structure of cellophane–acrylamide graft copolymer by the ceric ion method

The relationship between the grafting yield and the structure of graft copolymer is studied by measuring the branched chain lengths, the number of branches, the crystallinities, and the diffraction intensities of the (101) and (101 ) + (002) planes determined by x-ray diffraction, and the distribution of branched polymers, observed by interferometry. Over a relatively wide range of grafting yield the number of initiating sites is almost constant and about 1–2 per 2 moles of cellulose chain. Therefore, the increase of grafting yield seems to be due mainly to the propagation of branched polymers. Branched polymers are assumed to be formed in cellulose crystallites both on the normal (101) planes and in the amorphous regions of cellulose. It is found that branched polymers grow from the outer layer into the inner part of the film as the grafting yield increases. At more than 250% of grafting yield, however, branched polymers are uniformly formed throughout the layer of film in which the crystalline regions of cellulose are gradually destroyed. This result agrees with the dimensional change of gel film during the reaction. The temperature dependence of tensile strength and elongation and the wet strength of graft copolymer are also investigated. At higher grafting yields, such as 250%, the crystalline structure of cellulose is disturbed by the formation of branched polymer, and no improvement in waterproofness can be expected from grafting; the secondary bonding between branched polymers may be presumed to be same as those among cellulose. In addition, the fine cracking of the film in the burst state is found to appear more easily as the grafting yield increases, in which the aggregating state of cellulose is recognized to be changed by the formation of branched polymer.     

Glutamine-supplemented parenteral nutrition improves gut mucosa integrity and function in endotoxemic rats

Seventy-seven pancreatic adenocarcinomas (60 Spanish and 17 Italian) were tested for Ki-ras gene mutations by analysis of polymerase chain reaction amplified sequences. Mutations involving codon 12 (GGT; gly) were detected in 16 Italian and 46 Spanish cases (80.5% in total). All Italian mutations involved the second base and were G to A transitions (GAT; asp) in 8 cases and G to T transversions (GTT; val) in the remaining 8. Forty-two Spanish mutations were characterized. Thirty-eight were at the second and 4 at the first base: asp in 24 cancers, val in 14, arg (CGT) in 2 and cys (TGT) in 2. Previous European studies and our present data show that 149 of the 186 pancreatic cancers harbored a codon 12 Ki-ras mutation (80%), the large majority affecting the second base (73%), with a transitions/transversions ratio of 1.3:1. However, the mutational pattern of cancers of the different European countries shows remarkable differences, both in the site of the mutation (first or second base) and in the ratio of transitions over transversions. Moreover, a significant subgroup of pancreatic carcinomas do not harbor Ki-ras mutations. The classification of pancreatic cancers, according to the presence or absence, and type of Ki-ras mutation, may be of importance in epidemiological studies. A critical reappraisal of existing epidemiological data, through a retrospective genotypic study using paraffin-embedded cancer samples, may reveal significant correlations with specific genotoxic agents.     

Interaction of Si3N4 with Ni–Cr alloy under N2 or Ar atmosphere

In relation to the joining of silicon nitride ceramics to metal, the interaction of Si3N4 with Ni–Cr alloy was investigated at temperatures from 1073 to 1573 K under N2 or Ar atmosphere.Reaction rates were determined by thermogravimetry and reaction products were examined by X-ray diffraction. CrN, Ni3Si,Ni5Si2, Ni2Si and (Cr, Si)3Ni2Si were produced under N2 atmosphere. In addition to these products, Ni3Si2,Cr3Si and Cr5Si3 also were produced under Ar atmosphere. The reaction products were considered from the standpoint of thermodynamics. While the incubation period was observed under Ar atmosphere, it was not observed under N2 atmosphere. The initial rates obeyed a linear rate equation. The rates at the later stage of reaction described a parabolic rate equation. The reaction mechanism model was proposed.     

Endoscopic transvesico-transurethral approach for repair of vesicovaginal fistula: initial case report

New synthesized polymerized complexes of 3-amino-1,2,4-triazole with transition metals such as Cu+2, Ni+2, Co+2 and Zn+2 were investigated for fungicidal activity. Most of the tested complexes showed fungicidal activity which is not connected with activity of copper fungicides.     

Optical phase retardation of Lorentzian force-type fibre-optic magnetic sensor

The sensing fibre of the Lorentzian force-type fibre-optic magnetic sensor is shown to behave as a clamped-clamped vibrating beam with a static deflection. Resultant optical phase retardation with the Lorentzian-force frequency is proportional to the magnetic field strength. Sensitivity enhancement is also suggested,based on the analysis.<>