Denaturation of Bovine Serum Albumin (BSA) and Ovalbumin by High Pressure, Heat and Chemicals

Both native and denatured protein samples were examined by determining fluorescence and specific rotation, and by polyacrylamide gel electrophoresis (PAGE) and differential scanning calorimetry (DSC). Denaturation of ovalbumin by pressure was much less than by heat or by the chemical denaturants. Ovalbumin was denatured under high pressure, as confirmed by the decrease in its a-helical content to 72% and DSC endothermic enthalpy to 61%, but it showed no change in the PAGE pattern. With bovine serum albumin decrease in fluorescence was observed after denaturation by chemicals, but it did not change under high pressure.     

Relative Activity of Oxygen Ions in Molten Sodium Phosphate as Determined from the Solubility of Sulfur Trioxide

The solubility of sulfur trioxide in sodium phosphate melts with Na₂O/P₂O₅ ratios from 1.0 to 1.4 was investigated at 653° to 1021°C. The oxygen-ion activity estimated from the solubility of SO₃ increased exponentially as the Na₂O/P₂O₅ ratio increased. This compositional dependence of the activity is discussed on the basis of a polymer model.     

新型Gemini阳离子表面活性剂的合成和性能（3）—在烷基链中引入易水解基团促进生物降解

概述了烷基链中含有酰受基和酯基的Gemini阳离子表面活性剂的合成,表面活性和生物降解性,含有酰胺基的Gemini阳离子具有优良的表面活性,但几乎不能生物降解,而含有酯基的Gemini阳离子不仅具有优良的表面活性,而且具有良好的生物降解性。     

Crack formation in mesophase pitch-based carbon fibres: Part II Detailed structure of pitch-based carbon fibres with some types of open cracks

Several mesophase pitch-based carbon fibres showing radial textures in their transverse alignments were observed by high resolution scanning electron microscope (HR-SEM) to elucidate the principal factor that induces the open crack in the transverse sections of the fibre along its fibre axis. The HR-SEM images of transverse sections exhibited various features in the alignment and shapes of the domains, although they were approximately arranged in the radial direction. The alignment of the domains was often variable in the locations from the outer part to the centre. Linear domains radially oriented in the outer part of the transverse section, that induce the circumferential shrinkage at the spinning and further heat-treatment steps, were essential for the development of open cracks with the PAC-man shaped fibre. Non-radial alignment or non-linear, bent or loop domains in the outer parts prohibited the development of the crack; these are observed in the fibres with the radial skin-random core and the onion skin-radial core alignments. Fibres without cracks in their as-spun or stabilized states usually showed shallow cracks even after the graphitization because the bent and loop domains in the intermediate and centre parts prohibited cracks from propagating into the centre part because the graphitic shrinkage along the domain shapes cannot be linear. This revised version was published online in November 2006 with corrections to the Cover Date.     

Crack formation in mesophase pitch-basedcarbon fibres: Part I Some influential factors for crack formation

The crack observable in the transverse section of mesophase pitch-based graphitized fibres was studied to clarify its development on spinning, stabilization, carbonization and graphitization, and to find the factors influential on the development on spinning. The crack was already observed as an embryo in the as-spun fibre of radial texture, which increased the opening angle according to the extent of shrinkage due to carbonization and graphitization. The spinning temperature, length/diameter, diameter and wall material of the spinning nozzle and the kind of mesophase pitch were found influential in crack development, defining the transverse texture and the extent of longitudinal alignment along the fibre axis. Although the radial texture defined under an optical microscope tends to give a crack, not all of such textures carried the crack, suggesting the necessity of more detailed classification of the texture in terms of alignment, shape and size of domains observed under high resolution scanning electron microscopy (HR-SEM). The factors revealed as being influential on the textures appear to be related to the apparent viscosity, the perfectness of the radial orientation and die-swelling at the outlet of the nozzle to modify the texture defined through the nozzle. The interaction of the mesophase pitch with the nozzle wall and flow properties should be emphasized as factors controlling the texture on spinning. This revised version was published online in November 2006 with corrections to the Cover Date.     

Determination of Hypoxanthine in Fish Meat with an Enzyme Sensor

An enzyme sensor specific for hypoxanthine (Hx) was developed using immobilized xanthine oxidase-membrane and an oxygen probe. Xanthine oxidase (E.C. 1.2.3.2.) was covalently immobilized on a membrane prepared from cellulose triacetate, 1,8-diamino-4-aminomethyloctane, and glutaraldehyde. Hx is oxidized to uric acid by the immobilized enzyme, the output current of the oxygen probe decreasing due to oxygen consumption. A linear relationship was obtained between current decrease and Hx concentration in the range 0.06–1.5 mM. The enzyme sensor could be used for more than 100 assays without decrease of output current After 30-day-storage at 5°C, no remarkable decrease of output current was observed. The enzyme sensor system was applicable to the simple, rapid, and economical determination of Hx in several fish meats including sea bass, saurel, mackerel, yellowfish, and flounder.     

Application of High Pressure for Spore Inactivation and Protein Denaturation

Our objective was to develop a method of sterilizing Bucillur stearothermophilus spores with minimal heating. Inactivation was achieved by spore destruction through six cycles of oscillatory pressurization at 70°C and 600 MPa, but inactivation was not complete within 60-min with continuous pressurization. Four pressurization cycles at 600 MPa and 5 min/cycle decreased the spore count from 10⁶ to 10²/mL, and six cycles decreased the count from 10⁶ to <10⁰. Spore inactivation was dependent on the adiabatic expansion velocity. On the other hand, protein denaturation by high pressures was due to phase changes of water under high pressure, and was not affected by adiabatic expansion velocity.     

Structural Approach to the Problem of Oxygen Content in Alpha Silicon Nitride

The crystal structure of α-Si₃N₄ was reinvestigated by an X-ray method using a single-crystal specimen prepared by chemical vapor deposition. The oxygen content of the specimen (0.05 ± 0.03%) was determined by 14 MeV neutron activation analysis. The α form crystallizes in the space group P31c with uniteell dimensions a =7.818 ± 0.003 Å and c = 5.591 ± 0.004 Å. The structure was refined by the full-matrix least-squares method using 1143 observed structure factors. The Si-N distances determind ranged from 1.715 to 1.759 Å, and the final value of R was 0.041. Structural evidences indicated that the α form is essentially pure Si₃N₄.     

Determination of Inosine-5-Monophosphate in Fish Tissue with an Enzyme Sensor

An enzyme sensor for IMP consisted of immobilized enzymes and an oxygen electrode. A nucleotidase (E.C. 3.1.3.5.), nucleoside phosphorylase (E.C. 2.4.2.1.) and xanthine oxidase (E.C. 1.2.3.2.) were immobilized on a membrane prepared from cellulose triacetate, 1,8-diamino-4-aminomethyloctane and glutaraldehyde. Optimum conditions for IMP determination were pH 7.8, 30°C, a flow rate of 1 ml min⁻¹ and sample volume of 20 μl. A calibration curve for IMP was linear up to 15 mM. This sensor could be applied to the determination of IMP in meats of sea bass, mackerel, yellowfish and saurel. Good correlative results were observed between the values obtained by the sensor and the conventional method. The sensor was stable for more than 15 days at 5°C and 100 assays.     

单一重金属胁迫对灯心草生长及生理生化指标的影响

通过盆栽试验研究了不同浓度处理水平的Cu、Cd、Pb、Zn、As五种重金属单一胁迫对灯心草生长及其生理生化特性的的影响。结果表明:种植灯心草土壤中的Cd、Pb、Cu三种重金属临界值可分别设定为10mg kg-1、100 mg kg-1、100mg kg-1。灯心草不适合在Zn污染的土壤中种植,土壤中As临界值尚需作进一步的研究来确定。各单一重金属胁迫对灯心草叶绿素的合成均有很大程度的抑制作用,剂量-效应关系明显。灯心草三种保护酶对于不同浓度处理水平重金属胁迫的响应不同:在土壤环境质量低浓度设置范围内三种酶有较好的协同效应能共同抵御重金属胁迫造成的膜伤害,表现出较强的自我调节能力。而在高浓度处理水平时,三种酶活性呈现不同的变化趋势。灯心草生理生化指标对重金属胁迫的响应存在元素种类之间的差异。各单一重金属对灯心草生长抑制及生理毒害效应大小排序为:Zn>As>Cu>Pb>Cd。