Use of chemical characteristics to predict the relative bioavailability of supplemental organic manganese sources for broilers

Twelve organic Mn sources and MnSO4 were evaluated by polarographic analysis and via solubility in buffers (pH 5 and 2) and deionized water. Fractions from solubility tests were evaluated by gel filtration chromatography for structural integrity. Organic Mn sources included five Mn methionine complexes (Mn Met A to Mn Met E), two Mn proteinates (Mn Pro A and Mn Pro B), and five Mn amino acids (Mn AA A to Mn AA E). Sources varied considerably in chemical characteristics. Chelation strength (Qf) ranged from weak (1.9 Qf-values) to strong complexes (115.4 Qf-values). No complexed Mn was found in filtrates at pH 2.0 or 5.0. A 42-d bioassay was used to estimate relative bioavailability of Mn sources for chicks fed diets supplemented with 60, 120, or 180 mg Mn/kg. Bone Mn, heart Mn, heart manganese-superoxide dismutase activity (MnSOD), and heart MnSOD mRNA increased (P < 0.001) as dietary Mn increased. Only heart MnSOD mRNA tended (P < 0.10) to differ among dietary Mn sources. For bioassays of Mn, the MnSOD mRNA level in heart was more sensitive than the MnSOD activity in heart or other indices. Relative to MnSO4 (assigned 100%), slope ratios of MnSOD mRNA levels in heart gave bioavailabilities of 99, 132, and 113% for Mn Met E, Mn AA B, and Mn AA C sources with weak, moderate, and strong chelation strength, respectively. The bioavailability of Mn was more closely related to chelation strength as measured by polarography than to chemical traits assessed by solubility or structural integrity.     

劲性钢筋混凝土偏心受压短柱的极限承载力计算

In this paper, a superposition method is proposed for calculating the ultimate strength of steel reinforced concrete (SRC) short columns. Calculation results of 31 SRC short columns, obtained by using seven methods, are compared with test results. It is s     

Ritz向量叠加法的改进及其应用

揭示了Ｒｉｔｚ向量叠加法的实质及存在的问题，发展了与外载频率相关的Ｒｉｔｚ向量叠加法及多维外载作用时的Ｒｉｔｚ向量叠加法。着重讨论了地震荷载作用下，用Ｒｉｔｚ向量叠加法进行结构反应计算的有效性及局限性。     

β—萘磺酸电还原中间产物的电化学—ESR研究

用现场电化学－ＥＳＲ谱学与自旋捕集技术研究了β－萘磺酸在铂电极上电还原的一间产物。通过中间产物与苯亚甲基叔丁基氮氧化物（ＰＢＮ）加合物的波谱分析，证实了该反应为自由基反应并遵从脱磺酸基的反应机理。     

视黄醇结合蛋白及视黄醇转运机制

视黄醇类结合蛋白(RBP)是视黄醇特异性的载体蛋白,存在于血浆和其他组织细胞中。它可通过与视黄醇类物质、甲状腺素运载蛋白(TTR)的相互作用完成肝脏和靶细胞之间的视黄醇的运输。本文就RBP的分类、功能以及其转运视黄醇的机制作一概述。     

2021年新疆棉花重大病虫害发生趋势

根据2020年新疆维吾尔自治区棉花主要病虫害发生情况,结合越冬基数、气候条件等因素,预测了2021年棉花重大病虫害发生趋势,为及时做好新疆棉花病虫害防控工作提供参考。     

2020年新疆棉花主要病虫害发生概况

根据各地植保系统调查数据,概述了新疆维吾尔自治区2020年棉花主要病虫害总体发生情况,并从越冬基数、气象条件、作物布局与耕作制度及栽培品种等因素进行了综合分析,为做好全区棉花病虫害防治工作提供参考。     

桑沟湾栉孔扇贝不同养殖方式及适宜养殖水层研究

在桑沟湾内，对栉孔扇贝Ｃｈｌａｍｙｓ（Ａｚｕｍａｐｅｃｔｅｎ）ｆａｒｒｅｒｉ（ＪｏｎｅｓｅｔＰｒｅｓｔｏｎ）的笼养与串耳养殖等不同养殖方式及不同水层（１ｍ、２ｍ、３ｍ、４ｍ）的养殖效果进行了综合试验和分析。结果表明：（１）串耳养殖的扇贝平均壳高增长比笼养扇贝生长快，两种方式效果差异极明显（Ｐ＜０．０１）；（２）串耳养殖方式以２ｍ为最佳养殖水层，其次为１ｍ和３ｍ，４ｍ水层最差，而且２ｍ与４ｍ的养殖效果存在明显差异（Ｐ＜０．０５）；（３）笼养方式的最佳水层为４ｍ，其养殖效果依次为４ｍ＞１ｍ＞３ｍ和２ｍ。试验显示，在不同的养殖方式下，栉孔扇贝最佳生长的养殖水层是不同的。本文还对产生这一差异的原因进行了分析讨论     

Structure and functional expression of a human interleukin-8 receptor

Interleukin-8 (IL-8) is a member of a family of pro-inflammatory cytokines. Although the best characterized activities of IL-8 include the chemoattraction and activation of neutrophils, other members of this family have a wide range of specific actions including the chemotaxis and activation of monocytes, the selective chemotaxis of memory T cells, the inhibition of hematopoietic stem cell proliferation, and the induction of neutrophil infiltration in vivo. A complementary DNA encoding the IL-8 receptor from human neutrophils has now been isolated. The amino acid sequence shows that the receptor is a member of the superfamily of receptors that couple to guanine nucleotide binding proteins (G proteins). The sequence is 29% identical to that of receptors for the other neutrophil chemoattractants, fMet-Leu-Phe and C5a. Mammalian cells transfected with the IL-8 receptor cDNA clone bind IL-8 with high affinity and respond specifically to IL-8 by transiently mobilizing calcium. The IL-8 receptor may be part of a subfamily of related G protein-coupled receptors that transduce signals for the IL-8 family of pro-inflammatory cytokines.     

山地烤烟垄沟覆膜揭膜时间试验研究

[目的]为了明确高海拔地区烤烟垄沟覆膜的揭膜时间。[方法]采用随机区组,设移栽后30 d揭膜(A)4、0 d揭膜(B)5、0 d揭膜(C)6、0 d揭膜(D)4个处理和1个对照(不揭膜),研究了山地烤烟垄沟覆膜不同揭膜时间对烤烟产量产值的影响。[结果]4个处理的株高、叶片数、叶长、叶宽、叶面积系数等农艺性状比对照有所提高;B、C处理产量与对照差异极显著,A、D处理与对照无显著差异;4个处理的产值、中上等烟比例均与对照差异极显著,但4个处理间差异不明显。B处理烟叶产量和产值均最高,分别为174.74 kg/667m2和2 023.45元/667m2,比对照分别增长10.96%和9.12%。[结论]该研究为烤烟覆膜栽培与揭膜技术的推广应用提供了科学依据。