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151.
Peter Junghans Jürgen Voigt Werner Jentsch Cornelia C. Metges Michael Derno 《Livestock Science》2007,110(3):280-287
We explored the applicability of the 13C bicarbonate dilution technique for determination of energy expenditure (EE) in young bulls in comparison to whole body indirect calorimetry (IC). Twelve bulls of a F2 German Holstein x Charolais cross (4.5 months, 332 ± 16 kg BM) received a diet providing 1000 kJ ME d− 1 kg BM− 0.75 and 4.3 g crude protein d− 1 kg BM− 0.75. Bulls were housed in respiration chambers and received an intravenous bolus of NaH13CO3 (A: 3 μmol kg BM− 1 (n = 2), B: 7 μmol kg BM− 1 (n = 4), C: 17.5 μmol kg BM− 1 (n = 6), 99 at.% 13C) into the jugular vein to measure EE. Simultaneously, EE was determined by IC. After the 13C administration blood samples and breath gas were collected from the animals in the respiration chamber during a 24-h period (7.00–7.00 h). The recovery of 13C in breath CO2 (% of 13C dose) was irrespective of NaH13CO3 dose (A: 69.7 ± 2.7%, B: 70.5 ± 4.5%, C: 75.0 ± 4.9%; P > 0.05). Only small amounts of 13C were excreted in urine (3.4 ± 2.6%) and feces (2.0 ± 1.3%). The EE determined by the 13C bicarbonate method using breath and blood 13C recovery rates as correction factors was not different from that measured by IC (816 ± 81 [blood] or 827 ± 101 [breath] vs. 820 ± 90 kJ d− 1 kg BM− 0.75). Bland–Altman analysis showed a 95% confidence interval for EE of ± 99 and ± 109 kJ d− 1 kg BM− 0.75 based on blood and breath 13C recovery, respectively. In conclusion, the 13C bicarbonate dilution method is appropriate to obtain reliable estimates of EE in young bulls using blood CO2 or breath CO2 under standardized experimental conditions, i.e. in the fasting state. 相似文献
152.
153.
用差式扫描量热法(DSC)对苯基异氰酸酯与木素、纤维素、木粉的反应进行探究.在不同升温速率下,试验对比苯基异氰酸酯分别与木素、木粉在绝干含水率和平衡含水率(木素为3%,木粉为5%)条件下的反应特征;同时研究木素存在下苯基异氰酸酯与纤维素的反应特性.基于对DSC图的讨论分析和Ozawa方程,求解苯基异氰酸酯分别与木素、木粉反应的活化能,初步揭示异氰酸酯分别与木素、纤维素、木材的胶接反应特性.研究表明:苯基异氰酸酯与木素反应温度和活化能相对于苯基异氰酸酯与木粉反应的温度和活化能要低;木素与纤维素混合时,异氰酸酯主要与木素反应,当纤维素的含量较大时,纤维素与异氰酸酯反应程度加大;当木材含水率为5%时,水分导致含水木材与异氰酸酯反应活化能降低了34%. 相似文献
154.
Wichert B Müller L Gebert S Wenk C Wanner M 《Journal of animal physiology and animal nutrition》2007,91(5-6):278-281
Measurements of nitrogen, carbon and energy balances were done on eight female adult cats aged approximately 1.5 years with the help of respiration chambers. The cats were fed with a marked dry food for kittens (Biomill kitten). Faeces and urine samples were collected with the help of a special cat toilet that allows the single collection of both materials. The calculated energy requirement of these eight female cats was 239.6 kJ ME/kg BW/day (R(2) = 0.98). Including the data, on 12 young male adult cats, of L?uger, (2001), an energy requirement of 238 kJ ME/kg BW/day (R(2) = 0.95) could be calculated. From these data, it can be followed that the energy requirements of young, active cats are higher than that of the older cats. The method of indirect calorimetry does not necessarily lead to lower energy requirements. 相似文献
155.
Simultaneous application of the euglycemic hyperinsulinemic clamp (EHC) and indirect calorimetry was used to examine heat production, fat, and glucose metabolism in lean and obese adult neutered male and female cats. The results show that in lean insulin-sensitive cats glucose oxidation predominated during fasting, whereas lipid oxidation became more prominent in obese cats. Insulin infusion during the EHC in lean cats and obese male cats led to a large increase in glucose oxidation, glycogenesis, and lipogenesis. It also led to an increase in glucose oxidation and glycogenesis in obese female cats but it was significantly less compared to lean cats and obese males. This indicates that obese females show greater metabolic inflexibility. In obese cats of either gender, insulin caused greater suppression of non-esterified fatty acids compared to lean cats suggesting that obese cats show greater fatty acid clearance than lean cats. The heat production per metabolic size was lower in obese cats than lean cats. This would perpetuate obesity unless food intake is decreased. The higher glucose oxidation rate in obese neutered male cats suggests that they are able to replete their glycogen and lipid stores at a faster rate than females in response to insulin and it implies that they gain weight more rapidly. Further studies are needed to investigate if the different response to insulin of male cats is involved in their higher risk to develop diabetes. 相似文献
156.
157.
Natural cellulosic fibres from various varieties of banana plants such as Red Banana, Nendran, Rasthaly, Morris and Poovan
have been extracted manually and the physico-chemical properties of these fibres are investigated. The tensile strength of
these fibres varies from 176 MPa to 525 MPa. The untreated fibres have more tensile strength than the treated one. The thermal
properties of these fibres are studied by Differential Scanning Calorimetry (DSC). Two DSC thermal peaks, one is around 25°C
to 180°C and the other is around 155°C to 240°C, are noticed. The tensile strengths have a direct correlation with the area
of the lower thermal peak (enthalpy) and activation energy of the DSC, and also with the moisture absorption characteristics.
The FTIR shows characteristic bands corresponds to cellulose. The reflections of the X-ray fibre diffraction pattern recorded
for the banana fibre have been correlated with the mechanical strength. 相似文献
158.
魔芋精粉中二氧化硫残留量的几种测定方法比较 总被引:1,自引:0,他引:1
[目的]比较魔芋精粉中二氧化硫(SO2)残留量测定方法的优缺点。[方法]使用改进的常量蒸馏微量滴定法和盐酸副玫瑰苯胺法,测定了3种不同产地魔芋精粉中的SO2残留量,比较了2种方法的优缺点。[结果]盐酸副玫瑰苯胺法测定的整体结果比常量蒸馏微量滴定法的结果偏大,但差异不显著;测得3种魔芋精粉的SO2残留量分别为云南健晶白芋2.35g/kg;四川宜宾白芋2.21g/kg;四川宜宾花芋1.93g/kg。[结论]2种方法的测定结果没有显著差异,其中常量蒸馏微量滴定法操作简便、实用。 相似文献
159.
The buffering of protons and hydroxyl ions in acid soils was studied by the addition of small amounts of HCl, H2SO4, and NaOH in consecutive batch experiments using surface soils and subsoils from two Cambisols and one Podzol. A chemical equilibrium model was used to study the main buffer processes. The model included inorganic complexation and multiple cation exchange, and also the solubility of jurbanite and Al(OH)3 for the subsoils. Buffering of protons was predicted quite well by the model for the surface soil of the Spodi-Dystric and Spodic Cambisols, suggesting that multiple cation exchange was the main buffer process. For the Podzol surface soil, however, the model overestimated proton buffering by cation exchange considerably. Hydroxyl buffering in acid surface soils could be described well by the model for the Podzol soil only. For the Cambisols, hydroxyl buffer reactions included not only cation exchange, but also solubilization of large amounts of organic matter and presumably deprotonation of dissolved organic carbon (DOC). Modelling proton and hydroxyl buffering in subsoils suggested that equilibrium with AJ(OH)3 was not maintained for the Podzol and spodic Cambisol. Sulphate sorption had to be considered to describe titration experiments in all three soils. The assumption of jurbanite being in equilibrium with soil extracts was useful only for the Spodi-Dystric Cambisol. 相似文献
160.
采用电位滴定法改进了测定甲醛含量的中性亚硫酸钠法,并对其准确度和影响因素进行了探讨。用改进的中性亚硫酸钠法测定栲胶中单宁胺甲基化产物的甲醛含量的实验结果表明,反应体系甲醛测得率93.82%,r=0.999,空白实验回收率97.74%,r=0.999,温度控制在15~20℃,反应后放置时间在1h之内稳定,该方法可以克服单宁溶液有色、浑浊无法用指示剂指示终点的缺陷,电位突跃范围宽,数据误差小,重复性好。实现了快速、简便、准确地滴定栲胶中单宁胺甲基化反应产物剩余甲醛的含量。 相似文献