Preparation and antibacterial activity of novel fluoroalkyl end-capped oligomers/silica nanocomposites-encapsulated low molecular biocides

Fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomer [R_F-(DOBAA) _n -R_F] reacted with tetraethoxysilane (TEOS) and silica nanoparticles in the presence of low-molecular weight biocides such as hibitane, hinokitiol, and hinokioil under alkaline conditions to afford R_F-(DOBAA) _n -R_F/silica nanocomposites-encapsulated these biocides in excellent to moderate isolated yields. Fluoroalkyl end-capped N,N-dimethylacrylamide oligomer [R_F-(DMAA) _n -R_F] and acrylic acid oligomer [R_F-(ACA) _n -R_F]/silica nanocomposites-encapsulated hibitane were obtained under similar conditions. Dynamic light scattering measurements showed that the size of these fluorinated nanocomposites-encapsulated biocides thus obtained is nanometer size-controlled. Additionally, these fluorinated nanocomposites were shown to have a good dispersibility and stability in methanol and water. Of particular interest, these fluorinated nanocomposites-encapsulated biocides were found to have a good antibacterial activity against Staphylococcus aureus, and these nanocomposites were applied to the surface modification of traditional organic polymers such as poly(methyl methacrylate).     

Intussusception caused by a carcinoma of the cecum during pregnancy: report of a case and review of the literature

Respiratory infections are the most common infection in children. They differ remarkably according to age, bacteria and viruses. Therefore a careful history of outbreak, age, former infections, involvement of surroundings, symptoms, etc are essential. The present study included 50 children, aged between 0.3 and 12 yrs, all treated ambulatorily. 21 received brodimoprim (B) and 29 erythromycin (E). Indications were: tonsillitis, bronchitis, otitis media, sinusitis and scarlet fever. Dosages were: B was given 10 mg/kg body weight (b.w.) initially followed by 5 mg/kg b.w., once-a-day. The duration of treatment varied between 4 and 14 days (mean 8.3 days). E was given 30.50 mg/kg b.w. 3 times per day; duration 4 to 14 days (mean 8.6 days). Overall results were: in group B:12 cures, 5 improvements, 3 failures; 1 not assessable. In group E: 20 cures, 8 improvements, 1 failure. Side effects: in group B: vomiting (1), skin reaction (2), discontinuation (2); in group E: skin reaction (1), diarrhea (5), diarrhea+vomiting (1); discontinuation (2). The differences in efficacy and tolerability in the two groups are not statistically significant. The improved compliance with a single versus t.i.d. dosages has to be taken into account.     

The blocking barrier effect on aluminum electromigration due totitanium layers in multilayered interconnects of LSI's

Experimental evidence of an increase in the resistance of a cathode-side metal line without any void generation is presented for a multilayered metal structure terminated by via-holes during electromigration tests. This resistance increase is reversed to the initial value by high temperature storage after electromigration testing. The increase in the resistance of multilayered metal structures is attributed to the vacancy accumulation in the cathode side due to the blocking barrier effect of the refractory metal layer in the via-hole     

Deformation of NiO single crystals below room temperature: dislocation configurations

NiO single crystals prepared by two crystal growth techniques (zone melting in an arc-image furnace and Verneuil crystallization have been deformed by compression along 001 at temperatures as low as 4.2 K, and the dislocation substructure observed by transmission electron microscopy. The Peierls mechanism has been suggested as the mechanism controlling the mechanical behaviour at the lower temperatures. The dislocations generated at cavities found in the zone-melted crystals may be responsible for the increase of the flow stress of these crystals compared with the Verneuil ones.     

Temperature Dependence of KIC for High-Pressure Hot-Pressed Si3N4 Without Additives

Temperature dependence of K_IC values for Si₃N₄ bodies sintered at high pressures without additives was studied from room temperature to 1400°C. Little change in K_K was found in this range.     

Molecular species of 1-O-alk-1′-enyl-2-acyl-, 1-O-alkyl-2-acyl- and 1,2-diacyl glycerophospholipids in Japanese oysterCrassostrea gigas (Thunberg)

Molecular species of 1-O-alk-1′-enyl-2-acyl-, 1-O-alkyl-2-acyl-, and 1,2-diacyl-sn-glycero-3-phosphoethanolamine (EPL) andsn-glycero-3-phosphocholine (CPL) of Japanese oysterCrassostrea gigas were analyzed by selectedion monitoring gas chromatography/mass spectrometry using electron impact ionization. The characteristic fragment ions, [RCH=CH+56]⁺ due to the alkenyl residue in thesn-1 position and [RCO+74]⁺ due to the acyl residue in thesn-2 position of alkenylacylglycerols, [R+130]⁺ due to the alkyl residue in thesn-1 position and [RCO+74]⁺ due to the acyl residue in thesn-2 position of alkylacylglycerols, [RCO+74]⁺ due to the acyl residues in thesn-1 and/orsn-2 positions of diacylglycerols, and [M−57]⁺ being indicative of the corresponding molecular weight, were used for structural assignments. For alkenylacyl EPL and CPL, 19 and 16 molecular species were determined, respectively. Two molecular species, 18∶0alkenyl-22∶6n−3 and 18∶0-alkenyl-22∶2-non-methylene interrupted diene (NMID), amounted to 53.2% and 47.9%, respectively. The alkylacyl EPL and CPL consisted of 16 and 20 molecular species, respectively, and the prominent components were 18∶0alkyl-22∶2NMID, 20∶1alkyl-20∶1n−11 (27.4%) and 20∶1alkyl-20∶2NMID (16.3%) in the former, and 16∶0alkyl-20∶5n−3 (23.0%) and 16∶0alkyl-22∶6n−3 (21.6%) in the latter. For the diacyl EPL and CPL, 14 and 51 molecular species were determined, respectively. The major molecular species were 18∶0–20∶5n−3 (37.4%), 16∶0–20∶5n−3 (14.2%) and 18∶1n−7–22∶2NMID (13.2%) in the former, and 16∶0–20∶5n−3 (33.4%) and 16∶0–22∶6n−3 (22.3%) in the latter. It was found that there were significant differences in the molecular species between the alkylacyl and diacyl EPL and the alkylacyl and diacyl CPL; the number of molecular species was larger in CPL than in EPL, while the number of total carbons and double bonds of the major molecular species were larger in the EPL than in the CPL. Alkenylacyl EPL were similar to alkenylacyl CPL in molecular species composition.     

Temperature Dependence of Young's Modulus and Internal Friction in Alumina, Silicon Nitride, and Partially Stabilized Zirconia Ceramics

The temperature dependence of Young's modulus and internal friction (Q⁻¹)in alumina, silicon nitride, and partially stabilized zirconia (Y-PSZ) ceramics was studied. Little change in Q⁻¹ was found for alumina, whereas Q⁻¹ for silicon nitride ceramics increased above 700°C. The Q⁻¹ of Y-PSZ increased markedly with increasing temperature up to a peak at ∼200°C.     

A polar coordinate integration scheme with a hierachical correction procedure to improve numerical accuracy on the boundary element method

In order to calculate accurate physical values of interior region by the boundary element method, a new approach is proposed to singular kernel integration which is applicable to general isoparametric elements and never fails, no matter where the internal point under consideration may be located. The integration scheme consists of two parts.First, the singular kernel functions are assumed to be reciprocal of the distance types. Then the present scheme describes on the quadrate boundary element. The element is subdivided into four triangular regions for which Gauss-Legendre numerical quadrature is applied.Secondly, a method is proposed to reduce residual errors in the application of the above mentioned numerical scheme. The boundary integrals to calculate interior physical values are expressed formally with exact and numerical error terms, and boundary values in error terms are expanded by a Taylor series around the interior point. To evaluate the coefficient of each derivative in the series, a boundary integral form of an identity with respect to a vector from the interior point to the boundary surface is derived. Error resulting from numerical integration of the identity is found to coincide with the coefficient of the derivative in the Taylor series. Thus, the correction factor for numerical errors is obtained.The present scheme was verified to be quite effective such that both the numerical error and CPU time became 1/100 less than those by the double exponential quadrature. Moreover, the present numerical scheme is applicable to general curved elements.