Optical Properties and London Dispersion Forces of Amorphous Silica Determined by Vacuum Ultraviolet Spectroscopy and Spectroscopic Ellipsometry

Precise and accurate knowledge of the optical properties of amorphous silica is important because of the increasing application of SiO₂ in optical and electrooptical devices, including photolithography masks for semiconductor fabrication, recently as a potential 157 nm mask substrate. The optical properties in the vacuum ultraviolet (VUV) region have been investigated, because they convey detailed information on the electronic structure and interatomic bonding of the material. In this work, we have combined spectroscopic ellipsometry and VUV spectroscopy to directly determine the optical functions of SiO₂ in this range, thereby reducing the uncertainty in the low-energy extrapolation of the data, essential for Kramers–Kronig analysis of VUV reflectance. We report the complex optical properties of SiO₂, over the range of 1.5 to 42 eV, showing improved agreement with theory when contrasted with earlier results. In addition to the features previously reported at 10.4, 11.6, 14.03, and 17.10 eV, new interband transitions have been observed at 21.3 eV along with O 2 s transitions at 32 eV. We found the bulk plasma peak to be 23.7 eV in the energy loss function spectrum. Based on the magnitude of these new results, the Hamaker constant for SiO₂|Vacuum|SiO₂ is 71.6 zJ, which is larger than the previously reported value of 66 zJ.     

在全省纺织行业中开展向邓建军同志学习的活动倡议书

全省纺织行业职工同志们:在刚刚结束的全国高技能人才工作会议暨第八届中华技能大奖和全国技术能手表彰大会上,我省黑牡丹(集团)股份有限公司维修电工、高级技师邓建军荣获“中华技能大奖”。这是继邓建军获得“全国劳动模范”“、全国五一劳动奖章”“、全国技术能手”“、全国青年岗位能手”“、全国职工职业道德建设十佳标兵”“、2005中国纺织行业年度创新人物”等荣誉称号后,又一次获得殊荣。邓建军同志作为全省高技能人才队伍中的一员,18年来由普通的技术工人成长为新时期知识型产业工人的代表,成为“江苏省有突出贡献的高级技师”、…     

Effects of feeding frequency and exogenous somatotropin on lipolysis, hormone profiles, and milk production in dairy cows

Effects of feeding frequency and exogenous bovine somatotropin on lactational performance and hormone profiles were examined with 12 multiparous Holstein cows. At 45 d postpartum, cows were assigned to one of two feeding systems. Concentrates were offered in two equal portions at 0800 and 1600 h or in 12 equal portions at 2-h intervals. Chopped alfalfa hay (2.6 kg/d) and barley silage (ad libitum) were fed at 0900 and 1500 h. At 136 d postpartum, cows within each feeding frequency were assigned in a single crossover design to injection of 30 mg of bST/d or solubilization vehicle. Feeding frequency did not influence any of the parameters measured nor did bST interact with feeding frequency. Somatotropin injection increased daily milk yield of cows by 4.4 kg and concentrations of fat and lactose in milk. Protein concentration and fatty acid composition of milk were not influenced by bST injection. Average plasma somatotropin concentrations were elevated threefold, peak concentrations were increased sevenfold, and concentrations at 48 h postinjection were 1.5 times control values. Plasma insulin concentrations were decreased by bST treatment. Results indicate that responses to short-term bST injection are not influenced by feeding frequency.     

Interactions between the structural domains of the RNA replication proteins of plant-infecting RNA viruses

Brome mosaic virus (BMV), a positive-strand RNA virus, encodes two replication proteins: the 2a protein, which contains polymerase-like sequences, and the 1a protein, with N-terminal putative capping and C-terminal helicase-like sequences. These two proteins are part of a multisubunit complex which is necessary for viral RNA replication. We have previously shown that the yeast two-hybrid assay consistently duplicated results obtained from in vivo RNA replication assays and biochemical assays of protein-protein interaction, thus permitting the identification of additional interacting domains. We now map an interaction found to take place between two 1a proteins. Using previously characterized 1a mutants, a perfect correlation was found between the in vivo phenotypes of these mutants and their abilities to interact with wild-type 1a (wt1a) and each other. Western blot analysis revealed that the stabilities of many of the noninteracting mutant proteins were similar to that of wt1a. Deletion analysis of 1a revealed that the N-terminal 515 residues of the 1a protein are required and sufficient for 1a-1a interaction. This intermolecular interaction between the putative capping domain and itself was detected in another tripartite RNA virus, cucumber mosaic virus (CMV), suggesting that the 1a-1a interaction is a feature necessary for the replication of tripartite RNA viruses. The boundaries for various activities are placed in the context of the predicted secondary structures of several 1a-like proteins of members of the alphavirus-like superfamily. Additionally, we found a novel interaction between the putative capping and helicase-like portions of the BMV and CMV 1a proteins. Our cumulative data suggest a working model for the assembly of the BMV RNA replicase.     

Predominant interactions between mu-conotoxin Arg-13 and the skeletal muscle Na+ channel localized by mutant cycle analysis

High-affinity mu-conotoxin block of skeletal muscle Na+ channels depends on an arginine at position 13 (Arg-13). To understand both the mechanism of toxin interaction and the general structure of its binding site in the channel mouth, we examined by thermodynamic mutant cycle analysis the interaction between the critical Arg-13 and amino acid residues known to be in the channel's outer vestibule. Arg-13 interacts specifically with domain II Glu-758 with energy of about -3.0 kcal/mol, including both electrostatic and nonelectrostatic components, and with Glu-403 with energy of about -2.0 kcal/mol. Interactions with the other charged residues in the outer vestibule were shown to be almost entirely electrostatic, because these interactions were maintained when Arg-13 was replaced by lysine. These results place the bound Arg-13 at the channel mouth adjacent to the P (pore) loops of domains I and II. Distance estimates based on interaction energies suggest that the charged vestibule residues are in relative positions similar to those of the Lipkind-Fozzard vestibule model [Lipkind, G. M., and Fozzard, H. A. (1994) Biophys. J. 66, 1-13]. Kinetic analysis suggests that Arg-13 interactions are partially formed in the ligand-channel transition state.     

Operant investigation of mating preference in female rats.

Permitted 4 female Long-Evans hooded rats to indicate preferred mating partners by giving them operant control over the choice of a pair of sexually active males. Pressing 1 of 2 levers released 1 of the pair of male rats which was then allowed a single sexual contact. It was possible for a female to establish a preference in less than 10 estrous matings. No preference was apparent during diestrus tests, but preference returned when the female was again placed in estrus. When the males released by the levers were rotated in the apparatus, those females showing a preference altered their behavior accordingly. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of gamma-ray and ethylene oxide sterilization on collagen-based wound-repair materials

The effects of 2.5, 5.0, 7.5 and 10 Mrad gamma-irradiation and ethylene oxide sterilization on collagen-coated vicryl mesh, on collagen film and vicryl mesh were investigated. No cytotoxic effects were observed towards either L929 cells or human fibroblasts with any of the treatments, even at the highest doses of irradiation. Although the rate of biodegradation and tissue reaction towards the test materials appeared to be relatively unaffected by ethylene oxide, the rate of breakdown in the lumbar muscles of laboratory rats was considerably increased by irradiation. Dose-dependent irradiation damage to the vicryl mesh was confirmed in vitro using viscometry and by an increase in the rate of hydrolysis in phosphate-buffered saline (PBS) at 37°C. Tensiometric studies on irradiated collagen films showed a dose-dependent reduction in both the break load and elongation before breaking. A small reduction in the break load and stretch to breaking was also observed following treatment with ethylene oxide. The findings presented favour ethylene oxide as a method of sterilization of both the composite membrane and its individual components. However, gamma-irradiation produced no toxic effects or adverse tissue reaction under the conditions described, and is more convenient to use. Hence, provided that the efficacy of the membrane would not be compromised by the higher rate of degradation, it could also be considered for sterilization of the material.