油菜籽焦磷酸:果糖-6-磷酸1-磷酸转移酶的动力学研究

采用DEAE-Sephadex A-50及磷酸纤维素柱层析,用底物亲和洗脱法从萌发油菜(Brassica napus)种子中分离纯化了焦磷酸:果糖-6-磷酸1-磷酸转移酶(PFP).纯化倍数679.7倍,比活力为21.75 单位/毫克.蛋白,活力回收率22.9%.酶的最适pH值为7.5,Mg2+和M2+n对酶有激活作用.进行酶的初级动力学及稳态动力学研究,对果糖-6-磷酸(F6P)表现为典型的米氏规律,Km值为3.33 mmol/L;对焦磷酸(PPi)的活力变化,在PPi浓度小于1.0 mmol/L时具有部分米氏酶特点(Km＝1.0 mmol/L),大于1.0 mmol/L时,PPi对酶有抑制作用.从两底物F6P和PPi的相互作用以及产物磷酸(Pi)与底物(F6P和PPi)的相互关系分析,初步推断油菜籽PFP的催化反应为双底物双产物的有序机制.     

一些拉普拉斯谱确定的图

如果与图G同拉普拉斯谱的图都与图G同构,则称图G由它的拉普拉斯谱确定.给出了三类基图为B(P_3,P_3,P_3)(即连接2点的3条长为2的内不交的路)的连通二部双圈图类H(n;n_1),H(n;n_1,n_2)和B(n;n_1,n_2).证明了H(n;n1),H(n;n_1,n_2)和B(n;n_1,n_2)是拉普拉斯谱确定的,且与完全图经并接运算后所得图也是拉普拉斯谱确定的.     

求解对流扩散方程的一类AGE方法

结合Crank-Nicolson格式和第二类Saul’yev非对称格式,设计求解对流扩散方程的交替分组显式方法.得到求解对流扩散方程的交替分组显式方法为该方法是绝对稳定的,且使用方便,适合并行计算,具有较好的精度.     

Population-size-dependent branching processes in Markovian random environments

A branching model {Z n} n≥0is considered where the offspring distribution of the population's evolution is not only dependent on the population size, but also controlled by a Markovian environmental process {ξ n} n≥0. For this model, asymptotic behaviour is studied such as limn→∞Z n and limn→∞Z n/m n in the case that the mean m k, θof the offspring distribution converges to m>1 as the population size k grows to ∞. In the case that {ξ n} n≥0is an irreducible positive recurrent Markov chain, certain extinction (i.e. P(Z n=0 for some n)=1) and noncertain extinction (i.e. P(Z n=0 for some n)<1) are studied.     

Nbn(n=2-15)小团簇的第一性原理研究

【目的】研究纳米尺寸Nbn小团簇的结构演变过程,为进一步讨论Nbn小团簇的催化氧化性质提供参考。【方法】采用基于密度泛函理论(包括PW91和BLYP函数)的第一性原理计算方法对Nbn(n=2-15)小团簇的几何结构进行优化计算。【结果】随着原子数n的增加,Nbn(n=2-15)小团簇的结构及其特性具有明显的变化,平均每原子结合能(Binding Energy)随着原子数的增加呈递减趋势。【结论】Nbn(n=2-15)小团簇随尺寸变化具有明显的奇偶震荡性,n为偶数时比n为奇数时的结构稳定,其中Nb4、Nb6、Nb8、Nb10、Nb12小团簇结构较为稳定。     

Effects of yttrium on the formation and magnetic properties of bulk metallic glassy (Fe,Co)-B-Si-Nb alloys

The bulk metallic glassy (BMG) rods of [(Fe_0.5Co_0.5)_0.72B_0.192Si_0.048Nb_0.04]_100-xY_x (x=0-6) and [(Fe_xCo_1-x)_0.72B_0.192Si_0.048Nb_0.04]₉₆Y₄ (x=0.5-0.8) were prepared by copper mold casting. The structure, thermal stability, and magnetic properties of the samples were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and vibrating sample magnetometer (VSM). Adding 1at% to 6at% of yttrium, the bulk glassy alloy rods of [(Fe_0.5Co_0.5)_0.72B_0.192Si_0.048Nb_0.04]_100-xY_x(x=0-6) with the diameter of 3 mm were not formed, and the sample with 4at% of yttrium showed less crystalline phase than others. When the Fe/Co atomic ratio was between 5:5 and 7:3, the bulk glassy alloy rods of [(Fe_1-xCo_x)_0.72B_0.192Si_0.048Nb_0.04]₉₆Y₄ (x=0.5-0.8) with the diameter of 2 mm were fabricated. In the (Fe, Co)-B-Si-Nb-Y BMGs, when the Fe content increased, the thermal stability, the supercooled liquid region, and the glass-forming ability (GFA) decreased, but the saturation magnetization (M_s) increased.     

Experimental and theoretical studies of the reaction between cationic vanadium oxide clusters and acetylene

The time of flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source and a fast flow reactor was adopted to study the reactivity of cationic vanadium oxide clusters （VinOS,） toward acetylene （C2H2） molecules under gas phase （P, - 1.14 kPa）, under near room temperature （T, - 350 K） conditions. Association products, VmOnC2H2^＋ （m,n = 2,4; 2,6; 3,7-8; 4,9-11; 5,12-13; 6,13-16, and 7,17）, are observed. The oxidation of C2H2 by （V2Os）n^＋ （n = 1 -3） is experimentally identified. The reactivity of （V2O5）n^＋ decreases as n increases. Density functional theory （DFT） calculations were carried out to interpret the reaction mechanisms. The DFT results indicate that a terminal oxygen atom from V2O5^＋ can transfer overall barrierlessly to C2H2 at room temperature, which is in agreement with the experimental observation. Other experimental results such as the observation of V206C2H2^＋ and nonobservation of V2O7,8C2H2^＋ in the experiments are also well interpreted based on the DFT calculations. The reactivity of vanadium oxide clusters toward acetylene and other hydrocarbons may be considered in identifying molecular level mechanisms for related heterogeneous catalysis.     

Effect of Co on the martensitic transformation,crystal structure and magnetization of Ni<Subscript>52.5</Subscript>Mn<Subscript>23.5</Subscript>Ga<Subscript>24</Subscript> based ferromagnetic shape memory alloys

Five(Ni52.5Mn23.5Ga24)100-xCox(x = 0,2,4,6,8) alloys were prepared by arc melting,and the effects of Co addition on the martensitic phase transformation,crystal structure and magnetization were investigated.The phase transformation temperatures Ms,Mf,As and Af are proportional to the content of Co in the(Ni52.5Mn23.5Ga24)100-xCox alloys,which appears to be due to the variation in the valance electron concentration.The Curie temperature is sensitive to the composition of the alloy.As the amount of Co changes,both the Co-Mn exchange interaction and the distance between Mn atoms change.These,in turn,affect the Curie temperature and magnetization behavior of the alloy.The martensite phases in all the alloys are domained in three different orientations,the domain boundary was determined to belong to the family of {112} lattice planes.     

New crystal structure of molecular complex 1-piperidine carboxylate-piperidinium-H<Subscript>2</Subscript>O studied by X-ray single crystal diffraction

Piperidine absorbs CO2 and H2O in air to form a molecular complex： piperidium-l-piperidinecarboxylate-H2O. The structure of the complex was characterized by X-ray single crystal diffraction. The crystal structure was determined to be triclinic, space group P1^-with a=0.648 6（8） nm, b=0.809 200） nm, c= 1.357 1（16） nm, a=96.96706）°, β =102.506（15）°,γ=104.202 05）°, Z=2. The complex is stabilized via five hydrogen bonds between the three components, N-O electrostatic interaction and O-O interaction （electron transfer） betweenl-piperidinecarboxylate and H2O. Due to electron transference of carbamate ion, the oxygen atom in water molecule is strongly negatively charged and the O-H bond is considerably shorter than that of the free molecule of water. The formation of the molecular complex is a reversible process and will decompose upon heating. The mechanism of formation and stabilization is further investigated herein.     

非连通图(P1∨Pn)∪Gr和(P1∨Pn)∪(P3∨r)及Wn∪St(m)的优美性

讨论非连通图((P₁∨P_n)∪G_r和(P₁∨P_n)∪(P₃∨_r)及W_n∪St(m)的优美性, 证明了如下结论： 设n,m为任意正整数, s=［n/2］, r=s-1, G_r是任意具有r条边的优美图, 则当n≥4时, 非连通图((P₁∨P_n)∪G_r和(P₁∨P_n)∪(P₃∨_r)是优美图； 当n≥3, m≥s时, 非连通图W_n∪St(m)是优美图. 其中, P_n是n个顶点的路, K_n是n个顶点的完全图, n是K_n的补图, G₁∨G₂是图G₁与G₂的联图, W_n是n+1个顶点的轮图, St(m)是m+1个顶点的星形树.     

3,4-dichlorotoluene ammoxidation to 3,4-dichlorobenzonitrile over VPO/SiO<Subscript>2</Subscript> catalyst

Ammoxidation of 3,4-dichlorotoluene (DCT) to prepare 3,4-dichlorobenzonitrile (DCBN) over silica supported vanadium phosphorus oxide catalysts has been studied. On the VPO/SiO₂ catalyst, the influence of the reaction temperature, the molar ratio of air/DCT, the molar ratio of NH₃/DCT in the feed gas and the space velocity (v ₁) on the conversion, yield and selectivity was observed. The most appropriate reaction condition is: reactionT=673 K,n(DCT):n(NH₃):n(air)=1:7:30 andv ₁=250 h⁻¹. At this optimum reaction condition, the conversion of DCT is 97.8%; the molar yield of DCBN is 67.4%. It was found that the addition of element phosphorus can improve the yield of DCBN compared with VO/SiO₂ catalyst. Foundation item: Supported by Youth Chen-Guang Project of the Committee of Science and Technology of Wuhan (20015005042) Biography: Huang Chi(1972-), male, Ph D, Lecture, research direction: ammoxidation.     

Walsh spectrum properties of rotation symmetric boolean function

Rotation symmetric function was presented by Pieprzyk. The algebraic configuration of rotation symmetric（RotS） function is special. For a Rots n variables function f（x1, x2, …, xn） we have f（ρn^k （x1, x2, …xn））=f（x1, x2, …, xn） for k=0, 1, …, n-1. In this paper, useing probability method we find that when the parameters of RotS function is under circular translation of indices, its walsh spectrum is invariant. And we prove the result is both sufficient and necessary.     

邻苯二甲酸二丁酯印迹聚合物的制备及其吸附性能研究

以邻苯二甲酸二丁酯(DBP)为模板分子、甲基丙烯酸(MAA)为功能单体、乙二醇二甲基丙烯酸酯(EGDMA)为交联剂、乙腈为溶剂,采用沉淀聚合法制备分子印迹聚合物(MIPs),并利用扫描电镜及红外吸收光谱法对MIPs进行表征,采用Scatchard和Langmuir模型进行分析。结果表明:(1)印迹聚合物对模板分子存在2类不同结合位点,一类结合位点的解离常数K_(d1)=0.053 g/L,最大表观结合量Q_(max1)=27.3 mg/g;另一类结合位点的解离常数K_(d2)=0.16 g/L,最大表观结合量Q_(max2)=42.8 mg/g。(2)吸附过程较好地满足Langmuir吸附方程,饱和吸附量为31.7 mg/g。     

Generalized Galerkin approximations for pseudoinverses and operator equations of the first kind

0 IntroductionLeqtuiliHnebaer afo rHimlbaenrtd sap baoceun.dLeedtlianaenardfufnbceti oan baolu onndeHd ,serse--spectively. Our goal is to seekv∈Hsuchthata(u,v) =f(u) , u∈ H (1)As a rule, we call the expression (1) a variational equationandva solutiontothis equation.By virtue of the Riesz repre-sentationtheorem,there exists a uniquely determined boundedlinear operatorA:H→Hsuchthata(u,v) =〈u,Av〉, u,v∈ H,where〈·,·〉is the inner product onH.If the sesquilinearformais also with posit…     

Synthesis and electrochemical characteristics of xLi2MnO3·(1−x)Li-(Ni1/3Co1/3Mn1/3)O2 compounds

xLi₂MnO₃·(1−x)Li(Ni_1/3Co_1/3Mn_1/3)O₂ (x=0.25, 0.40, 0.55) compounds were prepared by low-heating solid state reaction. In the voltage range of 2.70-4.35 V, the discharge capacity of the electrode decreased with the increase of x, with a better cyclability. However, when cycled between 2.7 and 4.6 V, the cathodes delivered much larger capacities and their capacities increased with the introduction of Li₂MnO₃. Moreover, it was found that the discharge capacity gradually increased with the cycle number. The reason for this phenomenon was discussed. It was found that the relatively low cut-off potential made the activation of the Li₂MnO₃ component in the compound a gradual process, which caused the increasing capacity.     

最小Q-特征值第二小的给定悬挂点数的非二部单圈图

图的最小Q-特征值常被用来衡量一个图的非二部程度,受到研究者的广泛关注。在路Pn-k-2的一端接出一个圈C3,另一端接出k个悬挂边,所得的n阶图记为Ukn(3)。范益政等人最近证明Ukn(3)是最小Q-特征值达到最小的图。在他们的基础上,证明C13(n-k-1)是最小Q-特征值达到第二小的图,其中C13(n-k-1)是将Ukn(3)的一条悬挂边移至与悬挂邻点相邻的非悬挂点上所得的图。     

三聚磷酸二氢铝二水物的合成和表征

用磷酸和氢氧化铝为原料制备三聚磷酸二氢铝二水物。用X-衍射、红外光谱、化学分析、DTA-TG结合X-ray分析,证明产品的化学结构式为AlH2P3O10*2H2O。其晶体结构属正交晶系,空间群为PZ1/bZ1/aZ/m,D92h,晶胞参数a=15.919×10-8 cm,b=8.884×10-8cm,c=9.936×10-8 cm,单位晶胞体积V=1 405×10-8 cm3,Z=6。防绣性能测试表明其防锈能力与红丹颜料相当。毒理学试验表明该颜料半致死量LD50=18.0 g/kg(小白鼠),属实际无毒级,符合食品容器及儿童玩具涂装的要求。     

Structural diversity and reactivity of d^10 metal- （4-pyridylthio）acetate system

The hydrothermal synthesis and crystal structures of four coordination polymers, namely, 2D [Zn（μ3-ta）（pytaH）]n （1）, 2D [Zn（μ3-pyta）Cl]n （2）, 1D [Cd（μ-pyta）2（H2O）]n （3）, and 3D [Cd（μ3-pyta）（μ-Cl）]n （4） （pyta = （4-pyridylthio）acetate, ta = thioglycolate）, are reported. They are based on （4-pyridylthio）acetate and its derived ligand. The ta^2- ligand present in 1 was generated from an in situ C（sp^2）-S bond cleavage of the pyta ligand. In these compounds, versatile intermolecular interactions, such as close S…S interactions and strong （O-H…O/N/S） or weak （C-H…O/S, C-H…Cl） hydrogen bonding interactions, play an important role in the formation of three-dimensional supramolecular networks in the solid state.     

Study on the charge transference and local magnetic moment of yttrium-cobalt compound

The electronic charge transference and local magnetic moment of the YCo₅ intermetallic compound were calculated using SCF-MO-DVXα method and multiple cluster model. The result shows that about one 4d-electron is transferred from anY atom to Co₁(2c), and the calculated local spin magnetic moments of Co_I(2c) and Co_II(3g) atoms in YCo₅ compound are 1.33 and 1.48μ _B , respectively, which are in very good agreement with experiments. Supported by the National Natural Science Foundation of China Qiao Haoxue: born in Apr. 1970, Master