High acidity of polycyano azatriquinanes—theoretical prediction by the DFT calculations

It is shown by the B3LYP/6-311+G(2d,p)//B3LYP/6-31G(d) calculations that the hexacyano derivative of aza-acepentalene is an extremely powerful superacid both in the gas phase and in DMSO as evidenced by the ΔH_acid = 255.1  kcal mol⁻¹ and pK_a (DMSO) = −26.5. Its synthesis is strongly recommended, in particular, since the related conjugate base hexachloro aza-acepentalenide anion was prepared recently.     

Symmetries and correlation inequalities for classicaln-vector models

We describe a new class of single spin measures on then-dimensional sphereS _r ⁿ of radiusr (n 4) for which Lebowitz-type [J. Lebowitz,J. Stat. Phys. 16:463 (1977)] inequalities hold. This is achieved by an appropriate parametrization ofS _r ⁿ . The above class includes the uniform measures onxs Rⁿ ¦x¦ r for any 0 p r. The second topic of this paper is an abstract formulation of the first Griffiths inequality [R. B. Griffiths,J. Math. Phys. 8:478 (1967)] and the underlying symmetry property.     

Absence of continuous symmetry breaking in a one-dimensional n−2 model

For a one-dimensional array ofS ^N–1 spins (N 2) with isotropic pair interactions (and more general systems) with J(j–i) obeying sup_n[n^–1 ₁ ⁿ j ²|J(j)|]<, we prove that every equilibrium state is invariant under the natural action ofSO(N). In particular, there is no long-range order of the conventional type. Included is the caseJ(n)=n ^–2.Research partially supported by U.S.N.S.F. Grant No. MCS-78-01885.S. Fairchild Scholar at Caltech. On leave from Departments of Mathematics and Physics, Princeton University, Princeton, New Jersey 08544.     

Ising-like field theory

A field theory model onR ² in which the basic fields are Ising spins instead of Gaussian spins is examined. Using statistical mechanics techniques we discuss the ultraviolet and the infrared problems. In particular we discuss a technique yielding the asymptotic expansion in of the ground state energy, as 0, without using the cluster expansion.Supported in part by Consiglio Nazionale delle Ricerche.     

蛋白质组学和代谢组学在微生物代谢工程中的应用

构建微生物细胞工厂是化学品、生物能源以及药物分子可持续生产的可行性策略。然而，微生物的代谢复杂、调控严谨，制约着目标产物高效合成。蛋白质组学和代谢组学可以从系统生物学角度分析酶和代谢物组分，从而理解复杂的生物系统，为微生物代谢工程改造提供重要线索。该文介绍了蛋白质组学和代谢组学在微生物代谢工程中的应用，包括基因组尺度代谢模型构建、菌株生物合成优化、指导菌株耐受性改造、限速步骤预测、植物次级代谢途径挖掘，从而为微生物合成天然产物提供新的基因或途径。在此基础上，该文还展望了生物大数据未来的发展方向。     

大功率LD封装技术的研究

提出一种新的LD列阵封装方法。把热沉形状改为台阶式，使稳态工作条件下的芯片前腔面散热速度提高，前后腔面温差大幅度降低，因此可以提高COD阈值，降低腔面退化率，且更方便于光纤耦合封装。利用Ansys软件对大功率LD稳态工作的温度分布进行模拟。结果发现：改进前的芯片前、后腔面温差为9．0K，改进后温差降为3．5K，降低了60%；热沉前、后端面的温差由原来的18．2K降为8．0K，降低了56％。     

基于DRFM的脉冲多普勒雷达组合干扰及其效能评估

脉冲多普勒雷达具有较强的抗干扰能力，对其实施有效干扰有一定的困难。本文仿真研究了两种基于数字射频存储器的脉冲多普勒雷达组合干扰技术，并分别提出了脉冲多普勒雷达压制性干扰和欺骗性干扰的干扰效果度量方法，该方法在具体应用场合更贴近于干扰抗干扰的动态对抗过程。     

超宽带(UWB)室内信道模型

最近几年,人们进行了许多超宽带信道模型的室内试验,提出了几种反映超宽带信道特性的模型.文中给出了路径损耗模型、修正的泊松模型、Δ-K模型、S-V模型模型、2簇模型和IEEE 802.15.3a标准模型等模型及其参数特征和优缺点,并分析了今后超宽带模型建模应该注意的问题.     

HFC网络中数字电视信号性能参数测试分析

光纤同轴混合(HFC)网是目前承载数字电视信号的主要传输媒质,HFC网络能否真正满足数字电视传输网络的要求,需要对HFC网络中数字电视信号性能参数进行测试分析.在讨论数字电视信号电平、误码率、调制误差比等主要性能参数的基础上,根据实际运营的有线数字电视HFC网络构建测试模型,测试了数字电视信号的性能参数,分析了数字电视信号在HFC网络中的传输情况.测试分析表明:在目前条件下,HFC网络能适应数字电视信号的传输,有一定的优越性.     

射频CMOS平面螺旋电感2-π等效电路模型参数的提取

从有理分式拟合方法出发,提出了用于射频CMOS平面螺旋电感2-π等效电路模型参数提取的新方法.通过比较提参后等效电路给出的S参数和实验测量的S参数,证明该方法的精度很高.此外,提参的策略非常直接,因此容易在CAD里面编程实现.提参得到的等效电路模型对于射频电路设计者来说也是非常有用的.