浅析中频热压烧结过程中影响金刚石钻头性能的因素

通过试验和分析，说明在中频热压烧结金刚石钻头过程中，钻头性能受各种因素综合影响，其主要因素是电磁场影响到胎体粉料和金刚石分布，模具配合间隙引起胎体的流失而导致金刚石浓度发生变化。文中分析了电磁场对钻头性能的影响与胎体中铁磁物质含量及金刚石浓度的关系，也分析了模具配合间隙对胎体流失而引起金刚石浓度变化的关系。在中频热压烧结，高铁磁质含量胎体和低金刚石浓度的前题下，采用新工艺制作钻头，金刚石分布得到改善，钻头在使用中取得了良好的效果。     

丙酮制浆对竹纤维长度的影响

以竹材为原料，探讨了在不同浓度有机溶剂、盐酸和催化剂等条件下，丙酮制浆对纤维长度的影响。丙酮制浆对纤维长度具有显著的影响，随着丙酮及酸浓度的增加，纤维长度减小；而随催化剂量的增加，纤维长度增长。在丙酮20％，盐酸浓度2％及催化剂浓度50g／L条件下，分离纤维的长度变化较小，且木素得率较高，分离效果较好。     

乙醇浓度在线测量超声波传感器的研制

根据超声波检测原理，自行设计能在线检测的超声波传感器探头，研究了在线乙醇浓度超声波传感器，发现温度是影响传感器灵敏度的重要因素之一，为此选择了换能器材料P和安装了测温铂电极，有效地降低了温度对超声波信号的影响，提高了检测的灵敏度，乙醇浓度超声波传感器有效检测浓度范围在93％～100％(V／V)，检测灵敏度为0．1％(V／V)，可在线测量无水酒精或燃料酒精产品的乙醇浓度。     

涤仿麻织物的碱减量处理

研究了涤仿麻织物在染整加工中的碱减量处理，探讨了碱剂NoOH，促进剂SN用量对减量率的影响。减量率随NaOH浓度的增加而提高，但在一定浓度范围NaOH浓度的变化对减量率影响较小，促进剂SN浓度低于0．5g/L,SN浓度的变化对减量率影响很大，0．5－1．5g/L影响较小，高于2g./L趋于平衡，碱减量处理改善了涤仿麻织物的透气性，光泽，使织物轻盈飘逸有仿丝感。     

基于响应面分析法的可食性小麦蛋白膜的研究

应用响应面分析法研究了谷朊粉浓度、甘油浓度、pH值、成膜温度对成膜特性的影响。实验结果表明，甘油浓度与pH值及其交互作用对蛋白膜抗拉强度和延伸率影响比较显著；对膜的透水性影响比较大的因素是甘油浓度、温度、谷朊粉浓度及甘油浓度与温度的交互作用；谷朊粉浓度、甘油浓度、pH值、温度以及它们的交互作用对蛋白膜的透氧性的影响都是比较显著的。     

羟丙基甲基纤维素和黄原胶浓度对初榨椰子油乳液及其模板油凝胶构建的影响

本实验采用乳液模板法制备了不同羟丙基甲基纤维素（HPMC）和黄原胶（XG）浓度的初榨椰子油凝胶，对所得乳状液和油凝胶进行了粒径分析、微观结构观察、流变测定、油损失和X-射线衍射（XRD）分析，探讨HPMC和XG浓度对初榨椰子油凝胶形成和物理性能的影响。微观结构和粒径分析结果表明:高浓度HPMC具有较好的乳化性能，获得油滴粒径较小的稳定乳液；XG浓度变化对油滴粒径的影响不显著。流变学结果表明:随着HPMC或XG浓度的增加，乳状液和油凝胶的机械强度也得到提高，所有油凝胶都表现出对时间的依赖性和结构的回复性。油损失结果表明:HPMC浓度的增加对油凝胶损失的影响尤为明显，变化幅度从19.6%降低为3.6%；XG浓度的增加也使油损失从9.62%降低为4.4%。但HPMC和XG浓度的变化对油凝胶的XRD图谱影响不明显。本实验为初榨椰子油凝胶的构建提供了理论基础，也为其实际应用提供了参考。     

铈盐—过硫酸盐复合引发壳多糖与丙烯酸丁酯的乳兴接枝共聚的研究

用硫酸铈铵盐和过硫酸钾－亚硫酸氢钠为引发剂、十二烷基苯磺酸钠为乳化合剂，考察了单体浓度，不同引发体系及引发剂浓度、聚合温度、聚合时间，壳多糖浓度对丙烯酸丁酯壳多糖接枝共聚反应的影响，用红外光谱和Ｘ－射线衍射对接枝共聚物结构进行了表征，并探讨了引发机理。     

乳清蛋白凝胶性能的研究

阐述了溶液的ｐＨ值和离子强度对乳清蛋白分散体系的溶胶－－凝胶过渡状态的影响，确定了乳清蛋白形成凝胶的的极限浓度和凝胶形成所需的最低加热温度，并论述了环境因子（ｐＨ，离子强度，蛋白质浓度）对乳清蛋白凝胶状态的影响。     

海鳗盐渍过程中的渗透脱水规律研究

研究了海鳗在盐渍过程中的渗透脱水规律。海鳗经盐渍发生了物理、化学和组织的变化。温度对鱼体盐渍的重量变化影响不是决定性的，食盐浓度是影响鱼体重量变化的关键因素；温度和浓度对于食盐渗透速度的影响是显著的，并且为正相关。电镜显示经过盐渍后的肌肉组织结构变硬和嚼密。在盐卤中氨基酸随着盐渍温度的提高溶出的数量增加。随着盐渍浓度的提高，盐卤中的氨基酸溶出的数量减少。而鱼体肌肉蛋白质的分解，盐渍浓度对其有较大影响。这些研究对于海鳗的腌制生产具有实际指导意义。     

烟草次生物质──烟碱对烟蚜影响的研究

采用田间调查和室内饲养的方法，结合化验分析结果，分析了烟草次生物质烟碱对烟蚜的影响。结果表明烟叶中烟碱的含量非常明显的影响着烟蚜在田间的种群数量，烟碱浓度与烟蚜数量呈明显的负相关性。全纯人工饲料饲养结果表明，烟碱的浓度不仅影响烟蚜的存活率，对烟蚜的胎生期、胎生量及存活时间也存在着明显的影响，饲料中烟碱浓度10×10-6以下时，对烟蚜的胎生期及胎生量基本没有影响，超过20×10-6就会产生明显的负作用。且随着烟碱浓度的提高，负作用明显加强。     

Airborne haloacetic acids

Haloacetic acid (HAA) concentrations were measured in air samples from a semi-rural and a highly urbanized site in southern Ontario throughout 2000 to investigate their sources and gas-particle partitioning behavior. Denuders were efficient for collection of gaseous HAAs, and the particle phase was collected on a downstream quartz filter with negligible breakthrough. Total HAA concentrations (i.e., gas + particles) ranged between <0.025 and 19 ng m(-3) for individual HAAs at both sites. The dominant airborne HAA was monochloroacetic acid (MCA), followed in decreasing order by dichloroacetic acid (DCA), trifluoroacetic acid (TFA), and trichloroacetic acid (TCA). Difluoroacetic acid (DFA), monofluoroacetic acid (MFA), and chlorodifluoroacetic acid (CDFA) were also frequently detected at lower concentrations. Between sites, TFA, DFA, MFA, and TCA concentrations were significantly higher in Toronto, while CDFA concentrations were higher in Guelph. HAAs were primarily in the gas phase all year; however, during colder months, particle-phase HAA concentrations increased relative to the gas phase. Trichloroacetic acid had the highest particle fraction (phi) for all detected HAAs, with a mean phi of 0.51 and 0.56 for Guelph and Toronto, respectively, and both vapor pressure and acid strength appeared to influence gas-particle partitioning. Temporal trends at both sites were partially explained by temperature, short-wave radiation, and particle mass (PM10), leading to indications of the respective sources. A simple deposition model indicated that dry deposition of TFA and TCA should not be neglected in temperate mid-latitude environments and that precipitation concentrations can be successfully predicted by the Henry's law constant.     

Maternal and fetal amino acid concentrations and fetal outcomes during pre-eclampsia

The pathophysiology of pre-eclampsia is contested, but one hypothesis indicates that it is a heterogeneous condition in which only a subset of affected women bear small-for-gestational age (SGA) babies. In intrauterine growth-restricted (IUGR) infants, placental transport of amino acids is diminished and the resulting decrease in cord-blood amino acid concentrations is thought to contribute to their stunted growth. In contrast, the metabolic syndrome (dyslipidaemia, hyperinsulinaemia, hyperglycaemia, hypertension and obesity) which is associated with high amino acid concentrations is more prevalent in women with pre-eclampsia. The focus of this study was to compare maternal and fetal serum amino acid concentrations during normal pregnancy and pre-eclampsia and to evaluate the associations between the amino acid concentrations and fetal growth. The results indicate that maternal and cord-blood amino acid concentrations were significantly higher in women with pre-eclampsia compared with normal pregnant women and the concentrations were inversely associated with measures of infant growth. Maternal and cord-blood amino acid concentrations were also significantly higher in pre-eclamptic mothers with SGA infants compared with pre-eclamptic mothers whose babies were not SGA. These data indicate that, in contrast to IUGR, pre-eclampsia is associated with enhanced placental amino acid transport or reduced fetal amino acid utilization. Furthermore, the data are consistent with the hypothesis that pre-eclampsia is a heterogeneous disease associated with the metabolic syndrome.     

云南剥隘鸡与河南肉鸡肌肉中肌苷酸含量的 比较研究

目的比较研究不同月龄、性别的云南剥隘鸡与河南肉鸡肌肉中不同胴体部位的肌苷酸含量。方法随机选取健康5月、7月龄左右的云南剥隘鸡、河南肉鸡,公母各10只,屠宰取胸肌和腿肌待测。采用高效液相色谱法测定出不同月龄(5、7月龄)、性别及胴体部位(胸肌、腿肌)的云南剥隘鸡和河南肉鸡肌肉中肌苷酸含量。结果云南剥隘鸡、河南肉鸡肌肉中肌苷酸含量分别为2.4374~3.3192 mg/g、2.2095~3.0220 mg/g;5月、7月龄的云南剥隘鸡肌肉中肌苷酸含量均显著高于同月龄的河南肉鸡(P0.05);云南剥隘鸡肌肉中肌苷酸含量高于同性别的河南肉鸡,其中2种品种的母鸡肌肉中肌苷酸含量差距更显著(P0.05);云南剥隘鸡胸肌、腿肌中肌苷酸含量均显著高于相同胴体部位的河南肉鸡(P0.05)。结论不同月龄、性别、胴体部位对2个品种鸡肌肉中肌苷酸含量的差异性均产生显著影响,云南剥隘鸡肌肉中肌苷酸含量要高于相同条件下的河南肉鸡。     

The effect of energy-rich and energy-reduced rations with n-alkane yeast portions on the fatty acid composition of fat stores of swine

In 3 test groups (11 pigs in each group), rations with an identical fatty acid pattern of the fat in the fodder (except C 17 acids) with a high energy level (energy concentrations = 131%), medium energy level (energy concentrations = 100%) and low energy level (energy concentrations 90 or 82%, resp.) were used. In the course of the investigation the fatty acid spectrum was studied by analyzing spinal fat biopsy specimen. An interrelation was found to exist between the energy supply and the fatty acid spectrum in the depot fat. When identical quantities of heptadecenoic and heptadecanoic acids were added to the fodder, a high energy level resulted in a reduced C17 acid content in the spinal fat, whereas a low energy level led to an increased C17 acid content in the spinal fat. Different energy concentrations caused a change in the contents of oleic acid, linoleic acid and linolenic acid in the spinal fat. With changed energy concentrations, the C16 and C18 acid content showed variations compared with the group given standard fodder. The myristin acid content showed almost no change.     

Automated measurements of ammonia and nitric acid in indoor and outdoor air

Simultaneous temporally resolved indoor and outdoor measurements of ammonia and nitric acid are valuable for determining the gas-particle equilibrium conditions governing concentrations of ammonium nitrate aerosol. We report the results of simultaneous automated indoor and outdoor measurements of ammonia and nitric acid concentrations made at an unoccupied, single-story residence in Clovis, CA during three periods from October 2000 to January 2001. The measurements were conducted as part of a controlled study to explore mechanisms governing indoor concentrations of fine aerosols of outdoor origin. The gas-phase measurements were performed using diffusion denuders and ion chromatography with 30 min temporal resolution and detection limits below 1 ppb. The conditions of the field experiment span a wide range of outdoor climate as well as natural and forced indoor conditions. During all periods ammonia concentrations were generally slightly higher indoors than out, with both outdoor and indoor concentrations varying in a range from approximately 5 to 30 ppb. Nitric acid was only detected in outdoor air in October 2000, at concentrations up to 3 ppb. During the October period, the product of outdoor nitric acid and ammonia concentrations sometimes deviated from that expected for equilibrium between gas and ammonium nitrate particulate phases and the degree and direction of disequilibrium were correlated with trends in air temperature. The consistently low indoor concentrations of nitric acid were not consistent with equilibrium between gas and particle phases and suggest that a combination of low penetration into the building and a high loss rate for nitric acid reduce indoor concentrations significantly below those outdoors.     

Modification of endometrial fatty acid concentrations by the pre-implantation conceptus in pasture-fed dairy cows

The current study determined whether the pre-implantation conceptus modified endometrial fatty acid concentrations. Oestrus was synchronized in 14 mature lactating cows and embryos were transferred on day 7. Cows were slaughtered 10 d later, with each uterine horn flushed, the pre-implantation conceptus located, and inter-caruncular endometrial tissue collected from the gravid horn (containing the pre-implantation conceptus) and non-gravid horn. Endometrial fatty acid concentrations in the gravid and non-gravid horn were compared using linear models in restricted maxiumum likelihood. Investigations of the correlations among selected fatty acids and trophoblast weight or uterine fluid interferon-tau (IFN-τ) concentrations were also undertaken. The presence of the pre-implantation conceptus had relatively minor effects on endometrial fatty acid concentrations, but the ω6:ω3 ratio was greater and concentrations of stearic and oleic acid were slightly increased in the gravid horn. In the gravid horn, a negative linear relationship between the concentration of arachidonic acid and conceptus weight and IFN-τ concentration in the uterine luminal fluid were observed. In contrast, there was a positive relationship between concentrations of dihomo-γ-linolenic acid in the non-gravid horn and conceptus weight. In conclusion, the presence of the pre-implantation conceptus appears to modulate endometrial fatty acids, as indicated by the differences in endometrial fatty acid concentrations in the gravid and non-gravid uterine horns. The physiological implication of these local effects of the pre-implantation conceptus, on reproductive success requires further investigation.     

Protein and amino acids contents of Libyan dates at three stages of development

The protein and amino acid contents of three Libyan date varieties (Taasfirt, Bikrari and Khadhrai) at different stages of fruit development were determined. The protein concentration in all three varieties was highest at the green stage. Seventeen amino acids were detected and quantified; their concentrations (dry weight basis) were higher in Khadhrai and Bikrari than in Taasfirt. At the green stage the concentrations of glutamic acid, aspartic acid, lysine, leucine, alanine and serine were highest. At the yellow and ripe stages, glutamic acid, aspartic acid, lysine, leucine, proline and glycine were present in high concentrations. For most amino acids the concentrations were higher at the yellow stage than at the ripe stage. Copyright © 2004 Society of Chemical Industry     

NUTRITIONAL STUDIES ON YEASTS DURING BATCH AND CONTINUOUS FERMENTATION. I. CHANGES IN VITAMIN CONCENTRATIONS

The changes in the concentrations of eight vitamins were followed during the fermentation of wort by Saccharomyces carlsbergensis in plant scale batch fermentor, pilot tower fermentor and laboratory-size continuous stirred tank reactor. During fermentation in batch fermentor, p-amino benzoic acid concentration increased fivefold, while pantothenate increased threefold with one yeast but showed a slight drop with another. Riboflavin and inositol concentrations changed only slightly; biotin and pyridoxin concentrations decreased two to threefold, but the nicotinic acid and thiamine concentrations dropped ten to twentyfold. The other fermentation systems gave, in general, different values, but trends similar to the changes observed during batch fermentations were evident. The concentrations of nicotinic acid, thiamine and p-amino benzoic acid (one yeast) in the beer at the end of storage had increased one and one-half to twofold over the concentrations at the end of fermentation; the other vitamins showed little change.     

Comparison of Pond-Raised and Wild Red Drum (Sciaenopsocellatus) with Respect to Proximate Composition, Fatty Acid Profiles, and Sensory Evaluations

The proximate composition, fatty acid profiles, and the sensory characteristics of pond-raised red drum were compared to wild red drum. The proximate compositions and sensory characteristics were similar for pond-raised and wild red drum. The major difference between samples was in the fatty acid profiles. The pond-raised red drum had higher linoleic acid and lower docosahexaenoic acid concentrations than the wild fish samples. The eicosapentaenoic acid concentrations were similar in both pond-raised and wild red drum.     

Changes in amino acid and fatty acid composition during shelf‐life of marinated fish

Quality aspects of marinated fish were examined over a 120 day period. Nutritional quality parameters (proximate composition, fatty acid profile and amino acid profile) were determined. Changes in amino acids and fatty acids were examined in the muscle of marinated fish during storage. Aspartic acid, threonine, proline, glycine, tyrosine and lysine concentrations in marinated anchovy and rainbow trout greatly influenced their quality. Polyunsaturated fatty acid concentrations decreased significantly (p < 0.05) in marinated anchovy but not (p > 0.05) in marinated rainbow trout, while total saturated fatty acid concentrations increased significantly (p < 0.05) in both marinated fish during storage. These changes in fatty acid and amino acid concentrations were found to be useful as an index of freshness and decomposition of marinated fish in storage. Copyright © 2005 Society of Chemical Industry