结扎家兔颈总动脉和椎动脉后额区皮质超微结构变化──突触和突起

成年家兔１５只,分实验组和对照组。实验组动物结扎双侧颈总动脉和一侧椎动脉后分成Ⅰ,Ⅱ,Ⅲ组,分别存活３０ｍｉｎ,１ｈ和２４ｈ．对两侧大脑半球额区皮质的相同部位进行了电镜观察。突触活性区（突触前、后膜和突触间隙）电子密度增加,分辨不清突触间隙,在Ⅱ组这种突     

Picone type identities and definiteness of quadratic functionals on time scales

In this paper we derive a new sufficient condition for the nonnegativity of time scale quadratic functionals associated to time scale symplectic systems. To establish this result, a new global Picone formula is derived. Another proof of a special case of the result is shown to be obtained via a Sturmian comparison technique. Furthermore, we derive several new Picone type identities which, in particular, do not impose a certain delta-differentiability assumption, and we survey known ones from the literature. The results in this paper complete our earlier work on the definiteness of a time scale quadratic functional in terms of its corresponding time scale symplectic system.     

Sufficient conditions for variational problems with variable endpoints: Coupled points

In this paper we demonstrate that the notion of coupled points developed in [29] for the variable endpoints variational problems is the analog of that of conjugate points when the endpoints are fixed. We provide weak and strong local optimality criteria using the strengthening of necessary conditions involving both the coupled points and the regularity concepts.This research was supported by a grant from NSERC Canada and a summer support from Michigan State University.     

Analysis of soybean protein-derived peptides and the effect of cultivar, environmental conditions, and processing on lunasin concentration in soybean and soy products

Soybean, an important source of food proteins, has received increasing interest from the public because of its reported health benefits. These health benefits are attributed to its components, including isoflavones, saponins, proteins, and peptides. Lunasin, Bowman-Birk inhibitor, lectin, and beta-conglycinin are some of the biologically active peptides and proteins found in soybean. This article provides a comprehensive review on the recently used techniques in the analysis and characterization of food bioactive peptides, with emphasis on soybean peptides. The methods used to isolate and purify lunasin from defatted soybean flour were ion-exchange chromatography, ultrafiltration, and gel filtration chromatography. The identity of lunasin was established by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blot, matrix-assisted laser desorption ionization-time of flight, and liquid chromatography. The results on the effect of soybean cultivar and environmental factors on lunasin concentration are also reported. The highest lunasin concentration, 11.7 +/- 0.3 mg/g flour, was found in Loda soybean cultivar grown at 23 degrees C; the lowest concentration, 5.4 +/- 0.4 mg/g flour, was found in Imari soybean cultivar grown at 28 degrees C. Lunasin concentration was affected by cultivar-temperature, cultivar-soil moisture, and cultivar-temperature-soil moisture interactions. The variation on lunasin concentration suggests that its content can be improved by breeding, and by optimization of growing conditions. In summary, bioactive peptides can be accurately identified and quantified by using different techniques and conditions. In addition, lunasin concentration in soybean depends mainly on cultivar and to some extent on environmental factors, particularly temperature. Lunasin concentration in soy products was also affected by processing conditions.     

Synthesis and structure of mycolactone E isolated from frog mycobacterium

The structure of mycolactone E, isolated from the frog pathogen Mycobacterium liflandii, was established via organic synthesis. Within the mycolactone family of metabolites, a structural variation has been seen only at the unsaturated fatty acid moiety thus far, and mycolactone E follows this observation. Interestingly, the absolute configuration of its unsaturated fatty acid matches that of the mycolactones from human mycobacteria, rather than the structurally more closely related mycolactone F from fish mycobacteria.     

Organized surface functional groups: cooperative catalysis via thiol/sulfonic acid pairing

The synthesis and characterization of heterogeneous catalysts containing surfaces functionalized with discrete pairs of sulfonic acid and thiol groups are reported. A catalyst having acid and thiol groups separated by three carbon atoms is ca. 3 times more active than a material containing randomly distributed acid and thiol groups in the condensation of acetone and phenol to bisphenol A and 14 times more active in the condensation of cyclohexanone and phenol to bisphenol Z. Increasing the acid/thiol distance in the paired materials decreases both the activity and selectivity. This work clearly reveals the importance of nanoscale organization of two disparate functional groups on the surface of heterogeneous catalysts.     

Discrete Optimal Control: Second Order Optimality Conditions

In this paper, we present a survey and refinement of our recent results in the discrete optimal control theory. For a general nonlinear discrete optimal control problem (P) , second order necessary and sufficient optimality conditions are derived via the nonnegativity ( I S 0) and positivity ( I >0) of the discrete quadratic functional I corresponding to its second variation. Thus, we fill the gap in the discrete-time theory by connecting the discrete control problems with the theory of conjugate intervals, Hamiltonian systems, and Riccati equations. Necessary conditions for I S 0 are formulated in terms of the positivity of certain partial discrete quadratic functionals, the nonexistence of conjugate intervals, the existence of conjoined bases of the associated linear Hamiltonian system, and the existence of solutions to Riccati matrix equations. Natural strengthening of each of these conditions yields a characterization of the positivity of I and hence, sufficiency criteria for the original problem (P) . Finally, open problems and perspectives are also discussed.     

Second Order Sufficiency Criteria for a Discrete Optimal Control Problem

In this work, we derive second order necessary and sufficient optimality conditions for a discrete optimal control problem with one variable endpoint and the other fixed, and with equality control constraints. In particular, the positivity of the second variation, which is a discrete quadratic functional with appropriate boundary conditions, is characterized in terms of the nonexistence of intervals conjugate to 0, the existence of a certain conjoined basis of the associated linear Hamiltonian difference system, or the existence of a symmetric solution to the implicit and explicit Riccati matrix equations. Some results require a certain minimal normality assumption, and are derived using the sensitivity analysis technique.     

Nonnegativity and positivity of quadratic functionals in discrete calculus of variations: survey

In this paper we provide a survey of characterizations of the nonnegativity and positivity of discrete quadratic functionals which arise as the second variation for nonlinear discrete calculus of variations problems. These characterizations are in terms of (i) (strict) conjugate and (strict) coupled intervals, (ii) the conjoined bases of the associated Jacobi difference equation, and (iii) the solution of the corresponding Riccati difference equation. The results depend on the form of the boundary conditions of the quadratic functional and, basically, we distinguish three types: (a) separable endpoints with zero right endpoint (this of course includes the simplest case of both zero endpoints), (b) separable endpoints, and (c) jointly varying endpoints.     

Multiplicities of focal points for discrete symplectic systems: revisited

In this note, we define a notion of multiplicity of focal points for conjoined bases of discrete symplectic systems. We show that this definition is equivalent to the one given by Kratz in [Discrete oscillation, J. Difference Equ. Appl., 9(1), 135–147 (2003)] and, furthermore, it has a natural connection to the newly developed continuous time theory on linear Hamiltonian differential systems. Many results obtained recently by Bohner, Do?lý, and Kratz regarding the non-negativity of the corresponding discrete quadratic functionals, Sturmian separation and comparison theorems, and oscillation theorems relating the number of focal points of a certain special conjoined basis with the number of eigenvalues of the associated discrete symplectic eigenvalue problem, are now formulated in terms of this alternative definition of multiplicities.