复合酸化剂对中后期AA肉鸡消化道pH值的影响

研究不同水平的复合酸化剂对35、42日龄肉鸡腺胃、肌胃和十二指肠pH值的影响.结果表明:添加复合酸化剂组与对照组相比,均可有效降低35、42日龄肉鸡腺胃pH值(P＜0.05);0.2%和0.3%添加组可有效降低35、42日龄肌胃pH值及35日龄十二指肠pH值(P＜0.05),对42日龄十二指肠pH值有一定的降低作用(P＞0.05).     

远程光通信设备的供电方案探讨

光缆物理网作为最贴近用户的战略性资源,是争夺业务的关键性基础物理网络。如何为光通信设备提供安全、经济和便利的供电,是通信运营商和建设者非常关心的课题。本文简要介绍了远程光通信设备的供电方式及需要考虑的相关问题。     

Fuel model development for the Greek East‐Mediterranean forest litter layer

In order to develop fuel models used as input in wildland fire propagation models, it is necessary to determine relevant vegetation properties concerned with the prediction of the combustion process. This research considers property measurements of two biomass species, namely Pinus halepensis and Pinus brutia. Both species are commonly found in Greece and other Eastern Mediterranean countries. The physical application of the biomass properties relates to the structure of pine forest litter. Measurements have been recorded of the characteristics of the litter layer in situ, and common fuel properties have been determined in the laboratory using samples of the two litter species. In addition, DTA, TG and DTG analysis were performed of the two litter species. The results of the measurements are presented in a format suitable for input in fire propagation models. Comparisons of data have been made with those from other literature sources. Copyright © 2012 John Wiley & Sons, Ltd.     

Residues of nitrofuran antibiotic parent compounds and metabolites in eyes of broiler chickens

Nitrofuran antibiotic residues in food continue to be of international concern. The finding of sources of semicarbazide (SEM), other than through the misuse of nitrofurazone, present a challenge to the use of SEM as a definitive marker residue for this drug. Detection of intact (parent) nitrofurazone would avoid confusion over the source of SEM residues. Broiler chickens were fed sub-therapeutic nitrofuran-containing diets and their tissues were analysed for parent compounds and metabolites by liquid chromatography coupled with tandem mass spectrometry detection (LC-MS/MS). Depletion half-lives in muscle were longer for tissue-bound metabolite residues, 3.4 days —3-amino-2-oxazolidinone (AOZ), 3-amino-5-morpholinomethyl-2-oxazolidone (AMOZ)?—?to 4.5 days (SEM), than total metabolite residues, 2.0 days (AOZ) to 3.2 days (SEM). Metabolite concentrations were higher in eyes than in muscle. Metabolite half-lives in eyes ranged from 8.5 days (1-aminohydantoin (AHD)) to 20.3 days (SEM). Nitrofuran parent compounds were also detected in eyes. Furaltadone was detected in single eyes after 21 days’ withdrawal of a 6 mg kg^?1 furaltadone diet. When 50 eyes from broilers containing metabolites in muscle close to the 1 µg kg^?1 minimum required performance level (MRPL) were pooled into single samples, 1.2 ng of furazolidone and 31.1 ng of furaltadone were detected, but nitrofurazone was not detected due to the long depletion half-life of SEM in muscle. Further studies are required to improve LC-MS/MS nitrofurazone sensitivity and refine the sample size necessary to use nitrofurazone detection in pooled eyes as a complement to SEM detection in muscle.     

Fate of Tannins in Corsican Pine Litter

Tannins are ubiquitous in higher plants and also in litter and soils where they affect many biogeochemical processes. Despite this well-recognized role, their fate in litter and mineral soils is hardly known, as often only trace amounts, if any, are measured. In this study, we conducted an incubation experiment with Corsican pine litter to which known amounts of tannic acid (TA) or condensed tannins (CTs) from Corsican pine were added. Using Folin–Ciocalteu as a measure for total phenolics and HCl–butanol as an assay specific for CTs, acetone/water extractable phenolics and tannins decreased with time towards very low levels. Application of thermally assisted hydrolysis and methylation to litter before and after acetone/water extraction revealed that TA concentration decreased. By contrast, CTs remained to a great extent in the litter and could not be extracted suggesting that they were tightly bound.     

Nutritional composition and condensed tannin concentration changes as browse leaves become litter

BACKGROUND: The role of condensed tannins (CT) in ruminant nutrition and health makes changes in leaf litter (LL) after abscission of interest. This study compared the effect of different drying methods of green leaves (GL) with that of natural drying of LL on CT, fibre, crude protein (CP) and phosphorus (P) concentrations in nine Texas browse species. Leaves harvested before autumn shedding were oven‐dried (OD) or freeze‐dried (FD). RESULTS: Where different (P < 0.05), extractable CT concentrations were higher while protein‐ and fibre‐bound CT concentrations were lower in GL‐FD than in LL. Drying method changed total CT concentration in three species. Where different, fibre fraction concentrations were greater in LL than in GL, regardless of drying method. In some species, CP and P concentrations were lower in LL than in GL, but in five species they did not change (P > 0.05) from GL to LL, with CP concentrations ranging from 63 to 151 g kg^?1 in the latter. CONCLUSION: Browse LL had high nutritive value and CT concentrations, explaining why browsing ruminants utilise this feed resource. However, changes in nutrient and CT concentrations as leaves become litter in some species mean that information on one is not necessarily applicable to the other. Copyright © 2010 Society of Chemical Industry     

表面双稳铁电液晶中的层结构

从铁电液晶（ Ｆ Ｌ Ｃ）的物性出发， 描述了表面双稳铁电液晶（ Ｓ Ｓ Ｆ Ｌ Ｃ）显示结构原理和相应特点； 系统地介绍了 Ｓ Ｓ Ｆ Ｌ Ｃ 中的液晶层结构分类及相关特征。阐述了不同层结构对液晶器件双稳态的获得及电光特性的影响。