ω-Conway 环与ω-归纳*-半环

引入了ω-Conway半环与ω-归纳*-半环的概念,并且研究了它们的性质.得到了ω-归纳*-半环是ω-Conway半环.对ω-归纳*-半环的形式幂级数半环进行了讨论.结果表明,ω-Conway半环(ω-归纳*-半环)的矩阵半环仍然是ω-Conway半环(ω-归纳*-半环).     

ω-Conway 环与ω-归纳*-半环

引入了ω-Conway半环与ω-归纳*-半环的概念,并且研究了它们的性质.得到了ω-归纳*-半环是ω-Conway半环.对ω-归纳*-半环的形式幂级数半环进行了讨论.结果表明,ω-Conway半环(ω-归纳*-半环)的矩阵半环仍然是ω-Conway半环(ω-归纳*-半环).     

部分*-λ-半环

在*-λ-半环理论的基础上,引入了部分*-λ-半环的概念,研究了它的一些性质.得出了n∈N,部分*-λ-半环S上的n阶上(下)三角矩阵半环是部分*-λ-半环;系数在S上的形式幂级数半环也是部分*-λ-半环;并且给出了初始的*-λ-半环中的元素.     

部分归纳~*-半环

将部分Conway半环进行推广,得到了更一般的的Kleene定理.通过引入部分(弱)归纳*-半环的定义,研究了对这两类半环性质,给出了部分(弱)归纳*-半环与部分Conway半环的关系,得到了部分(弱)归纳*-半环上的Kleene定理.所得结果推广(弱)归纳*-半环上的Kleene定理,丰富了半环理论.     

UF-归纳~*-半环和UF-弱归纳~*-半环

对归纳*-半环和弱归纳*-半环进行更深入的研究.通过引入UF-归纳*-半环和UF-弱归纳*-半环的定义,给出了这两类半环的性质,讨论了它们之间的关系.并研究了这两类半环上的形式幂级数半环与矩阵半环,获得了一些结果.所得结果丰富了*-半环并推广*-半环上的一些重要理论.     

一类特殊的归纳~*-半环

研究了一类特殊的归纳*-半环.通过给出一种具体的星号运算,并从这一具体的运算出发,构造了一类特殊的归纳*-半环.得到了一类特殊的归纳*-半环,并得到了一些性质,给出了一些应用.能够在同一代数结构上通过定义不同的星号运算得到相应的归纳*-半环,如果能够恰当的定义星号运算,将会使这一代数结构变得更加清晰.     

一类幂等元半环的结构

研究一类重要的幂等元半环,即满足恒等式x xy x≈xy的幂等元半环.从多个角度对满足恒等式x xy x≈xy的幂等元半环作出了刻画.运用半环的强单演双半格刻画了此类幂等元半环的结构.在一定条件下,S满足恒等式x xy x≈xy当且仅当S是.Lz∩ R中半环的强单演双半格.     

双醛氧化纤维素固定化β-半乳糖苷酶

以双醛氧化纤维素为载体固定化β-半乳糖苷酶,研究了固定化酶的制备条件、微观结构及酶学性质,结果表明:固定化时间为4 h,[酶]/[载体]=1:15(g:g)时,固定化酶的活力最高为0.517 U/g。红外光谱和扫描电镜对固定化酶的微观结构研究表明,双醛氧化纤维素的醛基与β-半乳糖苷酶的氨基发生共价反应形成固定化酶。与游离酶相比,β-半乳糖苷酶经过固定化后热稳定性和耐酸碱性增强,米式方程分析表明,β-半乳糖苷酶经固定化后与底物的亲和力降低,固定化酶重复使用5次后,相对酶活力为63%。     

黑曲霉耐酸性α-半乳糖苷酶的分离及其酶学性质

采用耐酸性黑曲霉(Aspergillus niger L.)发酵豆渣产α-半乳糖苷酶,粗酶液依次经过聚乙二醇6000-KH2PO4双水相萃取、Sephadex G-100凝胶过滤,获得了电泳纯的α-半乳糖苷酶,纯化倍数为36.4,总酶活力回收率达到70%。凝胶过滤表明:该酶表观分子质量为125kD,SDS-PAGE显示其分子质量为58.5kD。该酶水解对硝基苯-α-D-吡喃半乳糖苷的最适pH值为4.0,最适温度为65℃,表观Km值为0.915mmol/L,表观kcat/Km值为1.07×105L/(mol.s);水解蜜二糖的表观Km、kcat/Km值分别是21.0mmol/L、9.96×103L/(mol.s);对棉子糖只有微弱的水解作用。水解活性受多种金属离子的普遍抑制,其中Fe3+、Fe2+、Mn2+、Hg+等强烈抑制酶活力。该酶活力在pH1.5～8.2保持稳定,在60℃时保温60min,剩余酶活力达到了60%,是一种热稳定酸性α-半乳糖苷酶。     

β-半乳糖苷酶催化制备甜菊双糖苷

甜菊双糖苷是具备某些生理活性的萜类化合物,同时也是制备一些抗结核、抗菌药物的中间体。本文用单因素实验考察了β-半乳糖苷酶催化水解甜菊苷制备甜菊双糖苷的工艺条件,结果表明:在反应温度40℃,pH7.0,底物浓度25mg/mL,加酶量8440U/gSt,水解时间12h,甜菊苷转化率为98.4%,甜菊双糖苷产率达94.9%。     

李代数对的Atiyah class

基于李代数胚对的Atiyah class理论,研究李代数对(L,A)的Atiyah class,其中L是李代数,A是L的李子代数。根据李代数对的Atiyah class定义,分析李代数的正合序列,得到了李代数对的Atiyah class为0的判定定理。应用该定理计算了四维空间中一些李代数对的Atiyah class。     

Selecting mating pairs with linear programming techniques

Mate selection can increase progency merit if overall merit is nonlinear for one or more component traits. An index of expected progeny merit could be calculated for all possible mating pairs, and the set of pairs with the highest progeny mean could be selected. There are serious computational problems for more than a few males and females. To select and mate f, females, and m, males, from n of each, with k0 females per male, would require (nf)(nm)f!/(k0!)m evaluations. Linear programming algorithms can determine the optimal strategy efficiently by considering only a subset of these possibilities. Let pi ij be the index of progency merit of the ith sire mated to the jth dam and Xij be the decision variable for that mating (restricted to 0 or 1). Then the problem of selecting mating pairs can be stated as: maximize sigma i sigma j pi ij Xij, subject to sigma i Xij less than or equal to 1, sigma j Xij less than or equal to k0, sigma i sigma j Xij = f, and Xij = 0 or 1. By including an artificial sire and an artificial dam and choosing appropriate merit values for the artificial matings, this problem can be solved by efficient "transportation" algorithms. These algorithms could be used to develop rational mating packages for dairy artificial insemination studs provided that an objective evaluation of progeny merit could be formulated, provided that merit is not simply additively inherited.     

Two primer pairs to detect OTA producers by PCR method

Fungi contaminating foods and feeds may produce many mycotoxins including ochratoxin A (OTA). Early and rapid detection of potential OTA producing fungi is important to reduce the negative impacts of OTA. In this study, two PCR specific primer pairs, AoLC35-12L/AoLC35-12R and AoOTAL/AoOTAR, were designed from a DNA sequence of a polyketide synthase gene in Aspergillus ochraceus NRRL 3174. On 14 different fungi tested by PCR, AoLC35-12L/AoLC35-12R amplified a unique band from either OTA or citrinin producers while AoOTAL/AoOTAR amplified one PCR product only from A. ochraceus. So these primers could be used to detect both OTA and citrinin producing fungi (AoLC35-12L/AoLC35-12R) or only A. ochraceus (AoOTAL/AoOTAR) from foodstuffs using PCR method.     

可控算子对的谱配置问题

设(?)和(?)为复Hiblert空间,给定算子A∈(?)((?)),B∈(?)((?))。当算子对(A,B)是可控算子对时,通过空间分解、极分解及构造算子矩阵的技巧,利用数学归纳法给出著名谱配置定理的一个比较清晰的证明,然后给出这个定理的一个应用.     

Withdrawal of pairs of threaded rods with small edge distances and spacings

An experimental investigation on withdrawal of pairs of screwed-in threaded rods embedded in glued-laminated timber elements is presented in this paper. Specimens with varying angles between the rod axis and the grain direction (α?=?15°, 30°, 60°, 90°) and 2 different configurations with respect to edge distances and spacings were tested. The diameter and the embedment length of the rods were 20 and 450 mm, respectively. The threaded rods were embedded in a row perpendicular to the plain of the grain. The edge distances and spacings were smaller than the minimum requirements according to Eurocode 5. The withdrawal capacity of pairs of rods was compared to the withdrawal capacity of single rods and the effective number, n _ef , was found to be in the range 1.72–1.94, despite the small edge distances and spacings. Based on the experimental results obtained, a simple approximating expression was derived for n _ef . An analytical model based on Volkersen theory with an idealized bi-linear constitutive relationship was used to estimate the withdrawal capacity and stiffness. The analytical estimations were in good agreement with the experimental results. Finally, the withdrawal stiffness was estimated by use of finite element simulations. The numerical estimations for the withdrawal stiffness were also in good agreement with the experimental results.     

A method of outdoor housing dairy calves in pairs using individual calf hutches

Interest in housing dairy calves in groups is currently growing. Group housing using individual calf hutches, a resource already available in most dairy farms in North America, could provide a novel housing method that can be a simple way to implement group housing on farm. The main objective of this study was to determine whether pair housing dairy calves in hutches outdoors would result in similar weight gain and milk intake compared with individual housing in hutches. The study was designed to avoid competition for resources (including milk and solid feed, teat, bucket, outdoor space, and hutch) to test a setup that has the potential to maximize performance and calf growth. Secondary objectives were to document how calves in both treatments use their environment in terms of time spent and behaviors performed in each area, how paired calves interact, and the time they spend together. Single calves (n = 6/season) were housed in 1 hutch with an attached outdoor environment; paired calves (n = 6 pairs/season) were given twice the resources. Calves were fed up to 16 L/d of milk replacer. Daily milk intake and weekly weight gains were recorded. Behavioral observations were recorded live once per week for 5 (summer) or 4 (winter) nonconsecutive periods. Paired and single calves had similar weight gain (averaging from 1.1 to 1.3 kg/d across trials) and milk intake (averaging from 11.1 to 13.7 kg/d across trials), showing no difference in performance between treatments. Low occurrences of cross sucking (averaging from 0.1 to 0.4 bouts/h of observation per pen across trials) and displacements at the teat (0.8 to 1.4 bouts/h of observation per pen across trials) were found. All calves altered their behavior in some way to accommodate companions; paired calves were seen interacting and spending time together (i.e., lying in the same hutch), and in the summer trial single calves spent less time lying inside the hutch than paired calves, presumably to have visual access to other calves. The solution of mixed indoor and outdoor housing environments tested as part of this study showed that calves make use of all spaces provided to them in winter and in summer conditions while maintaining good performance. Housing calves in pairs using individual hutches can be a suitable alternative to housing calves individually in hutches outdoors.     

Contribution of protein-surface ion pairs of a hyperthermophilic protein on thermal and thermodynamic stability

Hyperthermophilic proteins possess many ion pairs on their surface. To reveal the role of the ion pairs, O6-methylguanine-DNA methyltransferase from Thermococcus kodakaraensis KOD1 (Tk-MGMT) was studied as a model protein. The maximum free-energy changes of the protein in 0.1 and 0.5 M NaCl at pH 7.0 were 61.7 kJ mol(-1) at 31.5 degrees C and 77.4 kJ mol(-1) at 39.7 degrees C, respectively. On the other hand, mid points of the thermal unfolding temperatures in 0.1 and 0.5 M NaCl at pH 7.0 were 94.8 degrees C and 90.1 degrees C, respectively. The results suggest that the protein-surface ion pairs contribute to thermal stability (Tm), rather than thermodynamic stability (DeltaG).     

几种不能食用的肉

肉类食品的蛋白质含量丰富 ,其氨基酸组成与人接近 ,被称作优质蛋白质 ,有植物性蛋白质不可替代的功能。儿童生长所必需的赖氨酸主要存在于肉中 ,在粮谷中很少。肉类食品还是人体的 Fe、Zn、Cu等矿物质与脂溶性维生素的主要来源。肉类食品若摄取不足 ,人很易因蛋白质缺泛而造成营养不良 ,也很容易发生矿物质缺乏 ,引发缺铁性贫血等症。因此 ,在现代人的膳食中 ,肉类食品的比率越来越大。但你是否知道 ,有些肉却是不能吃的。(一 )畜甲状腺 ,又名“栗子肉”。位于喉头的前方 ,附在气管外面 ,为质地密实 ,色泽暗红的成对器官。它主要含甲状腺…