高精度双光束干涉指零仪的研制

在激光陀螺动态测角过程中,瞄准并建立一个可靠的零点是比较关键的问题。利用双光束干涉原理设计了指零仪的光路,描述了其瞄准原理和电路组成,分析了研制过程中应该注意的问题。利用高精度速率偏频激光陀螺的输出脉冲对指零仪进行了稳定性和重复性的实验,在转速为144(°)/s时指零仪的指零精度优于±0.1″,指零重复精度优于±0.05″。结果证明,所研制的指零仪具有很高的指零精度和良好的动态响应能力,验证了设计的合理性和可行性,为高精度激光陀螺测角仪的研制奠定了良好的基础。     

Barley Protein Isolate: Thermal, Functional, Rheological, and Surface Properties

Barley protein isolate (BPI) was extracted in 0.015 N NaOH in a 10:1 ratio solvent:flour and was precipitated by adjusting the pH to 4.5 and freeze-dried. The thermal properties of BPI were determined using modulated differential scanning calorimetry (MDSC). BPI with 4% moisture content exhibited a glass transition (T _g) with 140 °C onset, 153 °C middle, and 165 °C end temperatures and a ΔC _p of 0.454 J/g per °C. The high moisture content sample (50%) showed a T _g at 89, 91, or 94 °C and 0.067 ΔC _p. Acetylation had no apparent effect on the foaming and emulsifying properties of protein from barley flour but exhibited the least-stable foam among BPI samples. Foaming capacities of both barley protein isolates were ∼12% less than that of acid-precipitated soy protein isolate reported in the literature. Acetylated BPI showed the highest surface hydrophobicity compared to the other samples. The surface-tension test confirmed that unmodified and modified BPI possessed surface activity. BPI phosphorous oxycloride-crosslinked was the most effective in lowering the surface tension of aqueous NaCl, while the crosslinked BPI was the least effective. The G′ value of BPI suspension was greater than G″ at all frequencies from 0.1 to 100 rad/s. The strain value at which linear behavior ceased and nonlinear behavior began ranged from 3 to 10%. Names are necessary to report factually on available data; however, the United States Department of Agriculture (USDA) neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable.     

钝顶螺旋藻藻蓝蛋白的稳定性试验研究

用冻融的方法制备钝顶螺旋藻(Spirulina platensis)藻蓝蛋白并对纯化后的藻蓝蛋白稳定性进行了初步研究。提取后的粗提液经羟基磷灰石柱层析纯化后其纯度(A621／A280)达3.1温度、酸碱度、乙醇对藻蓝蛋白稳定性有较大影响；NaCl、苯甲酸钠、柠檬酸等食品添加剂对其稳定性影响较小。     

Leisure, home, and occupational physical activity and cardiovascular risk factors in postmenopausal women. The Postmenopausal Estrogens/Progestins Intervention (PEPI) Study

OBJECTIVE: To examine the associations between self-reported leisure, home, and occupational physical activity and selected cardiovascular risk factors. METHODS: A cross-sectional analysis of baseline data from the Postmenopausal Estrogen/Progestins Intervention Trial was performed in 851 women aged 45 to 64 years. Outcomes were levels of high-density lipoprotein cholesterol, insulin (2 hours after challenge), fibrinogen, systolic blood pressure. Race-stratified models were adjusted for age, smoking, alcohol, and previous noncontraceptive estrogen use. Models were also run with body mass index as an additional covariate. RESULTS: In white women, leisure physical activity was positively associated with levels of high-density lipoprotein cholesterol (P = .001) and inversely associated with levels of insulin (P = .04) and fibrinogen (P = .02). Compared with high-density lipoprotein cholesterol levels in the inactive and light leisure physical activity groups, moderate (P < .001) and heavy (P = .004) leisure activities were associated with higher high-density lipoprotein cholesterol levels. High-density lipoprotein cholesterol levels in the heavy leisure physical activity group were significantly higher than those in the moderate group (P = .01). Compared with lesser levels of leisure physical activity, significantly lower mean values of fibrinogen (P = .02) and insulin (P = .01) were associated with the highest-intensity leisure physical activity. Home physical activity was positively related to high-density lipoprotein cholesterol level (P = .01); relative to lower levels of home physical activity, the heavy home physical activity group demonstrated significantly higher mean high-density lipoprotein cholesterol levels. The effects of leisure and home physical activities were independent of each other. systolic blood pressure did not vary by leisure, occupational, or home physical activity. CONCLUSION: The unique relationships between type of physical activity and cardiac risk factors underscore the necessity of including multiple domains of activity in epidemiologic studies of epidemiologic studies of physical activity in women.     

Dietary patterns associated with a low-fat diet in the national health examination follow-up study: identification of potential confounders for epidemiologic analyses

To identify systematically the nutrient and food group intakes associated with a low-fat diet, the authors used the detailed dietary information collected from 10,306 individuals aged 32-86 years in the 1982-1984 National Health Epidemiologic Follow-up Study. Intakes of vitamin C and percentages of calories from carbohydrates, dietary fiber, poultry, low-fat dairy products, fruits, vegetables, cereals, and whole grains were markedly higher, while intakes of protein, total fat, saturated fat, oleic and linoleic acids, cholesterol, sodium, all red meats, high-fat dairy products, eggs, nuts, white bread, fried potatoes, desserts, fats, and oils were much lower in the quartile with the lowest percentage of calories from fat. These dietary patterns associated with a low-fat diet were essentially constant across strata of age, sex, race, and socioeconomic status. This study suggests that individuals on a low-fat diet substitute certain carbohydrate-rich foods such as fruits and vegetables for fat. Given these associations between low-fat diets and other dietary factors independently associated with certain cancers, these dietary factors should be considered potential confounders in studies of dietary fat and these cancers.     

B-scan ultrasonography in ophthalmic diseases

Real time B-scan ultrasonography was utilised on 318 eyes of 298 patients for evaluation of 285 (90%) eyes with opaque media; three (1%) eyes, with clear media but suspected intraocular abnormalities and for proptosis in 30 (9%) cases. Two hundred and nine (66%) eyes had one or more detectable abnormalities. The most common abnormality was retinal detachment (39%) followed by vitreous opacities (31%), eye ball size abnormalities (12%), intraocular foreign bodies (4%), posterior staphyloma (3%) and retinal detachment with vitreous opacities (2%). Twenty eight out of thirty patients evaluated for proptosis had abnormal orbital tissue patterns. Solid and cystic tissue patterns each accounted for 32% of the abnormal orbital studies followed by thyroid orbitopathy (25%), non specific (7%), and infiltrative (4%) tissue patterns. Detailed findings of B-scan ultrasonographic study is given in this paper. The paper reports further experience with the procedure in a developing country. In areas where other imaging techniques are not available the procedure is a valuable method of evaluating the eye and orbit for any detectable abnormalities and for planning management.     

Preparation and antihypertensive activity of peptides from Porphyra yezoensis

This research was to develop a antihypertensive peptide, an efficient angiotensin converting enzyme (ACE) inhibitor (ACEI), from Porphyra yezoensis. Seven commercial enzymes were screened and then enzymatic hydrolysis conditions were optimised. The results showed that alcalase was the most effective for hydrolysis and its optimum conditions for achieving the highest antihypertensive activity of peptide were 1.5% substrate, 5% alcalase, pH 9.0, and temperature of 50 °C at a hydrolysis time of 60 min. The antihypertensive peptide produced under the optimum conditions had a high ACE inhibition rate of 55.0% and a low IC₅₀ value of 1.6 g/l and remained at high stability at temperatures of 4, 25, and 37 °C, pH values of 2.0 and 8.0, and after pepsin and trypsin treatments. Major proteins from P. yezoensis were glutelin, albumin, and gliadin. The albumin and glutelin had higher hydrolysis rates than the gliadin, but the IC₅₀ value of glutelin was the lowest, which indicated that the antihypertensive peptide from glutelin was more functional.     

Modeling of drying and ameliorative effects of relative humidity (RH) against β-carotene degradation and color of carrot (Daucus carota var.) slices

Food Science and Biotechnology - Drying and β-carotenes retention kinetics were predicted using models in relative humidity (RH) drying condition. This was achieved by drying carrot slices...     

Biobased Poly-phosphonate Additives from Methyl Linoleates‡

Poly-dialkyl phosphonates were synthesized by reacting methyl linoleate with dimethyl, diethyl, and di-n-butyl phosphites in the presence of free radical initiator and positively identified and characterized using gas chromatography–mass spectrometry (GC-MS), nuclear magnetic resonance (NMR; ¹H, ¹³C, ³¹P), and Fourier transform infrared (FTIR). Neat poly-dialkyl phosphonates and their blends in high-oleic sunflower oil (HOSuO) and polyalphaolefin (PAO-6) base oils were investigated for their physical, chemical, and tribological properties. At room temperature, the poly-dialkyl phosphonates displayed much better solubility in HOSuO than in PAO-6. Solubility in the base oils increased in the order dimethyl?<?diethyl?<?di-n-butyl. Relative to methyl linoleate, the neat poly-dialkyl phosphonates displayed higher density, higher kinematic viscosity, higher oxidation stability, and better cold flow (lower pour point and cloud point) properties. As an additive (0–10% w/w) in HOSuO, increasing concentration of poly-di-n-butyl phosphonate resulted in increasing onset and peak oxidation temperatures and decreasing cloud point. Poly-di-n-butyl phosphonate blends in HOSuO also showed lower four-ball antiwear (AW) coefficient of friction (COF) and wear scar diameter (WSD) than corresponding blends with zinc dialkyl dithiophosphate (ZDDP). As an additive (0–10% w/w) in PAO-6 base oil, poly-di-n-butyl phosphonate displayed lower four-ball antiwear COF and comparable WSD relative to similar blends of ZDDP in PAO-6. The results indicate that poly-dialkyl phosphonates are promising biobased AW additives with comparable or better performance than current petroleum-based commercial AW additives such as ZDDP.     

Friction properties of chemically modified starch

Starches of varying chemical structures were esterified with anhydrides, formulated into dry film lubricants with the addition of canola oil, and its friction properties investigated. In the absence of canola, chemically modified starch displayed a very high coefficient of friction (COF). Addition of canola resulted in a sharp decrease in COF, which decreased with increasing [canola] until it attained a minimum and constant value that was independent of the further increase in [canola]. This observation was attributed to the adsorption of the canola oil onto starch due to H‐bonding between the ester groups of the canola triglycerides and the free hydroxyl groups of starch. Analysis of the [canola] vs COF data using the Langmuir adsorption model showed stronger adsorption of canola to modified starch with a lower degree of substitution (DS). This was attributed to the availability of more free hydroxyl group adsorption sites on starches with lower DS than those with higher DS. Copyright © 2008 John Wiley & Sons, Ltd.