溴化锂吸收式制冷机亚稳平衡增压吸收试验和机理

溴化锂吸收式制冷机组以水为制冷剂,环保,可利用废热、余热,达到综合利用和回收能源的目的。但是其较低的能效比限制其发展。本文基于二元溶液亚稳平衡吸收原理,对常规溴化锂吸收式制冷循环的吸收器进行了改造,建造了蒸汽增压装置,以强化吸收器特性、降低发生温度为目的进行了特性研究。研究结果表明,制冷量可以增加约2倍,传热面积约减小40%～55%,有利于机组小型化;机组增压范围在1.2～2.2 kPa间,机组COP值约提高1.5倍。     

消失模壳型铸造A356铸态和T6态铝合金的组织、性能及拉伸断口(英文)

对采用消失模壳型铸造制备的A356铝合金在铸态和T6热处理态下的微观组织、拉伸性能以及拉伸断口进行了研究,并与消失模铸造A356铝合金进行了对比分析。结果表明:消失模壳型铸造A356铝合金组织主要有α(Al)初生相、共晶硅相以及Mg2Si相组成。经过T6热处理后,共晶硅形貌更加球化,均匀地分布于晶界处;且共晶硅粒子的平均长度、宽度和长宽比都比铸态条件下的小。与消失模铸造相比,组织中的初生相和共晶硅相都明显细化。经T6处理后,消失模壳型铸造A356合金的力学性能得到明显提高,其中抗拉强度、延伸率和布氏硬度分别达到260.53MPa、6.15%和86.0,其与消失模铸造相比具有明显优势。此外,消失模壳型铸造A356铝合金拉伸断口为具有准解理面和韧窝形貌的混合断口,最终表现为穿晶断裂模式。而消失模铸造A356铝合金拉伸断口为明显的脆性断口。     

离子色谱在能源领域中的应用

离子色谱作为近20年来发展最快的分析技术之一,其应用已经渗透到众多领域。该文简要综述离子色谱在能源生产及研究中的应用,主要包括石油化工、核能和电力、可再生能源研究方面的应用。     

Glass formation and magnetic properties of Fe-based metallic glasses fabricated by low-purity industrial materials

Fe-based metallic glasses of (Fe₇₄Nb₆B₂₀)_100-xCr_x (x=1, 3, 5) with high glass forming ability (GFA) and good magnetic properties were prepared using low-purity raw materials. Increasing Cr content does not significantly change glass transition temperature and onset crystallization temperature, while it enhances liquidus temperature. The addition of Cr improves the GFA of the (Fe₇₄Nb₆B₂₀)_100-xCr_x glassy alloys compared to that in Cr-free Fe-Nb-B alloys, in which the supercooled liquid region (ΔT_x), T_rg and γ are found to be 50–54 K, 0.526–0.538, and 0.367–0.371, respectively. The (Fe₇₄Nb₆B₂₀)_100–xCr_x glassy alloys exhibit excellent soft magnetic properties with high saturation magnetization of 139–161 A·m²/kg and low coercivity of 30.24–58.9 A/m. Present Fe-Nb-B-Cr glassy alloys exhibiting high GFA as well as excellent magnetic properties and low manufacturing cost make them suitable for magnetic components for engineering application.     

Nonlinear pharmacokinetics of efavirenz (DMP-266), a potent HIV-1 reverse transcriptase inhibitor, in rats and monkeys

PURPOSE: Our purpose was to evaluate the L-ascorbate level in human preovulatory follicular fluid and to quantify the blood/follicle gradient for vitamin C. The effect of smoking on the follicular L-ascorbate concentration was studied. The correlations were tested between follicular L-ascorbate and follicle size and oocyte maturity. METHODS: In 65 women undergoing in vitro fertilization, samples of follicular fluid and blood serum were collected. Biochemical analyses included L-ascorbate determinations by a colorimetric method and cotinine measurements by a radioimmunoassay. RESULTS: The average follicular fluid:serum ratio for L-ascorbate was 1:68. Ascorbate levels in follicular fluid and serum were significantly correlated. The follicular L-ascorbate level did not correlate with the follicle size and the oocyte maturity grade. Insignificantly lowered follicular L-ascorbate levels were observed in smokers. CONCLUSIONS: The extracellular compartment of the Graafian follicle is a site of an ascorbate accumulation. Exposure to tobacco smoke does not significantly diminish the intrafollicular pool of L-ascorbate.     

Fatal cardiac rupture among patients treated with thrombolytic agents and adjunctive thrombin antagonists: observations from the Thrombolysis and Thrombin Inhibition in Myocardial Infarction 9 Study

We evaluated the hypotheses that endurance training increases relative lipid oxidation over a wide range of relative exercise intensities in fed and fasted states and that carbohydrate nutrition causes carbohydrate-derived fuels to predominate as energy sources during exercise. Pulmonary respiratory gas-exchange ratios [(RER) = CO2 production/O2 consumption (VO2)] were determined during four relative, graded exercise intensities in both fed and fasted states. Seven untrained (UT) men and seven category 2 and 3 US Cycling Federation cyclists (T) exercised in the morning in random order, with target power outputs of 20 and 40% peak VO2 (VO2 peak) for 2 h, 60% VO2 peak for 1.5 h, and 80% VO2 peak for a minimum of 30 min after either a 12-h overnight fast or 3 h after a standardized breakfast. Actual metabolic responses were 22 +/- 0.33, 40 +/- 0.31, 59 +/- 0.32, and 75 +/- 0.39% VO2 peak. T subjects showed significantly (P < 0.05) decreased RER compared with UT subjects at absolute workloads when fed and fasted. Fasting significantly decreased RER values compared with the fed state at 22, 40, and 59% VO2 peak in T and at 40 and 59% VO2 peak in UT subjects. Training decreased (P < 0.05) mean RER values compared with UT subjects at 22% VO2 peak when they fasted, and at 40% VO2 peak when fed or fasted, but not at higher relative exercise intensities in either nutritional state. Our results support the hypothesis that endurance training enhances lipid oxidation in men after a 12-h overnight fast at low relative exercise intensities (22 and 40% VO2 peak). However, a training effect on RER was not apparent at high relative exercise intensities (59 and 75% VO2 peak). Because most athletes train and compete at exercise intensities >40% maximal VO2, they will not oxidize a greater proportion of lipids compared with untrained subjects, regardless of nutritional state.     

对虾头酶解液Maillard反应中挥发性成分变化及影响因素

以南美白对虾虾头为原料,经中性酶酶解再经美拉德反应后,应用固相微萃取技术,对原料、酶解液、美拉德反应液中的挥发性物质进行GC-MS分析和比较,并研究反应温度、时间、pH、添加牛磺酸等因素对美拉德反应液挥发性成分的影响。结果表明,原料经酶解再到Maillard反应是一个醇类、醛类、酮类、酯类等物质相对含量减少,吡嗪类等物质生成的过程,且温度升高、反应时间延长、pH值升高及半胱氨酸盐酸盐的添加均能促进此趋势。     

新能源材料与器件专业《材料科学基础》教学探讨

《材料科学基础》是新能源材料与器件专业的一门专业主干课程,对学生材料科学知识结构搭建具有奠基作用,也是公共课程与专业课程过渡的重要桥梁。基于新能源材料与器件专业培养目标,结合许昌学院新能源研究特色领域与教学实际情况,针对性地探讨面向新能源材料与器件专业的《材料科学基础》课程结构、课程内容、教学手段、考核方式、实践教学等方面的科学调整与合理安排,进一步提高教学效果与教学质量。     

Biodegradability of [14C]methylcellulose by activated sludge

Three Methocel methylcellulose ethers of 1.9 degree of substitution with [14C]methyl labels were shown to be biodegradable using batch-type activated sludge tests. The maximum rate for conversion to 14CO2, attained after 1 week, was only 0.62 mg of methylcellulose/g of mixed liquor volatile solids per day. In 20 days, 55 to 73% of the radioactivity had been removed from solution as 14CO2, and the suspended solids contained 12 to 15% of the original radioactivity. Only 4% of the original methylcellulose appeared to be polymeric after the 20-day period. Thin-layer chromatography of supernatant liquid indicated at least two degradation products.     

Effects of growth hormone and pregnancy on expression of growth hormone receptor, insulin-like growth factor-I, and insulin-like growth factor binding protein-2 and -3 genes in bovine uterus, ovary, and oviduct

The effects of growth hormone (GH) and pregnancy on insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-2, and IGFBP-3 mRNA in reproductive tissues were studied in cattle. Lactating dairy cows were inseminated at estrus and treated with 25 mg/day GH (n = 8) or saline (n = 8) for 16 days. Corpus luteum (CL), ovary (CL removed), oviduct, endometrium, and myometrium were collected at the end of treatment. Messenger RNA for GH receptor, IGF-I, IGFBP-2, IGFBP-3, and actin were measured by nuclease protection assays. The CL contained more GH receptor mRNA than the other reproductive tissues examined. Expression of IGF-I mRNA was highest in myometrium, with lower amounts found in endometrium; the CL expressed the least amount of IGF-I mRNA. The IGFBP-2 mRNA was most abundant in endometrium and least abundant in CL. Expression of IGFBP-3 mRNA was detected in all reproductive tissues examined. However, endometrium, a tissue that expressed the most IGFBP-2 mRNA, had the lowest amount of IGFBP-3 mRNA. The GH receptor mRNA was decreased in cows treated with GH whereas the mRNA for IGF-I, IGFBP-2, or IGFBP-3 was not changed. In the reproductive tissues evaluated, cows that contained a conceptus at tissue collection (pregnant) had higher amounts of IGF-I mRNA than did nonpregnant cows. In summary, the level of mRNA encoding GH receptor, IGF-I, IGFBP-2, and IGFBP-3 varied within the tissues examined, suggesting that these genes may play a variety of roles in the bovine female reproductive tract. Supplemental GH failed to change the expression of IGF-I, IGFBP-2, and IGFBP-3 mRNA, possibly because of low GH receptor mRNA levels in tissues other than CL. A direct action of GH on IGF-I, IGFBP-2, or IGFBP-3 gene expression within cow reproductive tissues was not supported because the amount of IGF-I, IGFBP-2, or IGFBP-3 mRNA was not altered by GH.