热处理对CH薄膜表面粗糙度及力学性能的影响

利用低压等离子体化学气相沉积法制备厚度约为7 m的辉光放电聚合物薄膜,将制备的薄膜样品放入通有氩气保护的热处理炉中加热至300 ℃,分别进行6,10,24 h的保温热处理。通过白光干涉仪观察分析了不同保温时间下辉光放电聚合物薄膜的表面粗糙度; 利用傅里叶变换红外吸收光谱分析了300 ℃条件下不同保温时间对薄膜结构的影响; 采用纳米压痕仪表征了不同保温时间热处理后,薄膜硬度及模量的变化。结果表明:随着保温时间的增加,薄膜的表面均方根粗糙度由12 nm降至4.43 nm。薄膜结构中甲基的相对含量减少,双键的相对含量增加,碳链变长,同时薄膜网络结构的交联化程度增强。硬度和模量随着保温时间的增加先减小后增大。     

Electrical properties and emission mechanisms of Zn-doped β-Ga2O3 films

We study the electrical properties and emission mechanisms of Zn-doped β-Ga₂O₃ film grown by pulsed laser deposition through Hall effect and cathodoluminescence which consist of ultraviolet luminescence (UV), blue luminescence (BL) and green luminescence (GL) bands. The Hall effect measurements indicate that the carrier concentration increases from 7.16×10¹¹ to 6.35×10¹² cm⁻³ with increasing a nominal Zn content from 3 to 7 at%. The UV band at 272 nm is not attributed to Zn dopants and ascribed as radiative electron transition from conduction band to a self-trapped hole while the BL band is attributable to defect level related to Zn dopant. The BL band has two emission peaks at 415 and 455 nm, which are ascribed to the radiative electron transition from oxygen vacancy (V_O) to valence band and recombination of a donor–acceptor pair (DAP) between V_O donor and Zn on Ga site (Zn_Ga) acceptor, respectively. The GL band is attributed to the phonon replicas’ emission of the DAP. The acceptor level of Zn_Ga is estimated to be 0.26 eV above the valence band maximum. The transmittance and absorption spectra prove that the Zn-doped β-Ga₂O₃ film is a dominantly direct bandgap material. The results of Hall and cathodoluminescence measurements imply that the Zn dopant in β-Ga₂O₃ film will form an acceptor Zn_Ga to produce p-type conductivity.     

θ(t)-Caldern-Zygmund算子在群上的Hardy空间H~p(G)中的有界性

设Ｇ为局部域Ｋ上的２ｎ＋１维Ｈｅｉｓｅｎｂｅｒｇ群,文献［１］给出了一类Ｈａｒｄｙ空间 Ｈ~ｐ（Ｇ）,（０＜Ｐ≤１）,本文讨论了θ（ｔ）－Ｃａｌｄｅｒｏｎ－Ｚｙｇｍｕｎｄ算子在Ｈ~ｐ（Ｇ）（０＜Ｐ≤１）中的有界性。     

Duality and Polynomial Testing of Tree Homomorphisms

Let be a fixed digraph. We consider the -colouring problem, i.e., the problem of deciding which digraphs admit a homomorphism to . We are interested in a characterization in terms of the absence in of certain tree-like obstructions. Specifically, we say that has tree duality if, for all digraphs , is not homomorphic to if and only if there is an oriented tree which is homomorphic to but not to . We prove that if has tree duality then the -colouring problem is polynomial. We also generalize tree duality to bounded treewidth duality and prove a similar result. We relate these duality concepts to the notion of the -property studied by Gutjahr, Welzl, and Woeginger.

We then focus on the case when itself is an oriented tree. In fact, we are particularly interested in those trees that have exactly one vertex of degree three and all other vertices of degree one or two. Such trees are called triads. We have shown in a companion paper that there exist oriented triads for which the -colouring problem is -complete. We contrast these with several families of oriented triads which have tree duality, or bounded treewidth duality, and hence polynomial -colouring problems. If , then no oriented triad with an -complete -colouring problem can have bounded treewidth duality; however no proof of this is known, for any oriented triad . We prove that none of the oriented triads with -complete -colouring problems given in the companion paper has tree duality.

     

Monotone generalized variational inequalities and generalized complementarity problems

Some existence results for generalized variational inequalities and generalized complementarity problems involving quasimonotone and pseudomonotone set-valued mappings in reflexive Banach spaces are proved. In particular, some known results for nonlinear variational inequalities and complementarity problems in finite-dimensional and infinite-dimensional Hilbert spaces are generalized to quasimonotone and pseudomonotone set-valued mappings and reflexive Banach spaces. Application to a class of generalized nonlinear complementarity problems studied as mathematical models for mechanical problems is given.The research of the first author was supported by the National Natural Science Foundation of P. R. China and by the Ethel Raybould Fellowship, University of Queensland, St. Lucia, Brisbane, Australia.     

Optimal production control of a dynamic two-product manufacturing system with setup costs and setup times

This paper deals with the optimal control of a one-machine two-product manufacturing system with setup changes, operating in a continuous time dynamic environment. The system is deterministic. When production is switched from one product to the other, a known constant setup time and a setup cost are incurred. Each product has specified constant processing time and constant demand rate, as well as an infinite supply of raw material. The problem is formulated as a feedback control problem. The objective is to minimize the total backlog, inventory and setup costs incurred over a finite horizon. The optimal solution provides the optimal production rate and setup switching epochs as a function of the state of the system (backlog and inventory levels). For the steady state, the optimal cyclic schedule is determined. To solve the transient case, the system's state space is partitioned into mutually exclusive regions such that with each region, the optimal control policy is determined analytically.     

微波消解-ICP-MS测定动物血清和组织器官中的微量银元素

银的应用在当代生物医学领域得到极大地推广,其生物安全性也受到密切关注,明确银离子在生物体内分布以及其安全阈值显得格外重要。因此,需要一种高灵敏度的分析方法来确定医学生物样品中银的含量。电感耦合等离子体质谱(ICP-MS)法对于金属离子检测具有很高的灵敏度,非常适用于医学生物样品中所含痕量银元素的检测,但具体方法的开发,包括样品前处理和检测过程,尚处于起步阶段。本研究建立了一套简便易行的微波消解处理机体血清和组织器官样品,通过ICP-MS法测定样品内微量银元素的检测方法。血清和肌肉、骨髓、骨骼组织,以及心脏、肝脏、脾脏、肾脏器官样品经5 mL硝酸-2 mL过氧化氢体系微波消解。消解程序采用2 000 W功率3步式温度梯度,样品最终消解完全,获得的数据重复性好,且耗费时间短,为大批量样品处理节省了时间。消解溶液经稀释定容,在优化仪器工作参数后,用ICP-MS对溶液中的107Ag进行测定,以钇(Y)为内标元素补偿基体效应和准确度漂移。测定结果显示,107Ag元素检出限为0.98 μg·kg-1,标准曲线相关系数为0.999 9,回收率为98%～107%,相对标准偏差(RSD)为2.0%～4.3%。用该法测定了动物血清和组织器官中的银元素含量,发现机体摄入银离子后,主要蓄积在肝脏。检测结果表明ICP-MS方法可以准确地测定机体的微量银元素,所建立的方法适用性强,可满足不同类型医学生物样品中微量银元素的测定,操作简便快捷,结果准确且灵敏度高,尤其适合于大批量生物样品的检测,为其他生物样品微量元素的检测提供了指导。     

Investigation of the phase transitions of ferroelectric KIO3 and KNbO3 crystals by optical diffraction

Optical diffraction is reviewed as a technique for investigation of the phase transitions in crystals with a multidomain structure. It has been used to study the phase transitions in KIO₃ and KNbO₃ single crystals. Strong optical diffraction bands resulted from electric domains in KNbO₃ crystals and their change with temperature were observed when a laser beam passed through the crystals. The diffraction patterns observed changed abruptly at 427°C, 223°C, and -50°C respectively, at which KNbO₃ crystals undergo structural phase transitions. It is considered that the change of the diffraction patterns with temperature is due to change of the electric domains in the crystals.     

Nuclear and GP-Nuclear Groups

We define GP-nuclear groups as topological Abelian groups for which the groups of summable and absolutely summable sequences are the same algebraically and topologically. It is shown that in the metrizable case only the algebraic coincidence of the mentioned groups is needed for GP-nuclearity. Some permanence properties of the class of GP-nuclear groups are obtained. Our final result asserts that nuclear groups in the sense of Banaszczyk are GP-nuclear. The validity of the converse assertion remains open.     

Extended defects in shallow implants

Extended defects are often found after ion implantation and annealing of silicon and they are known to affect dopant diffusion. The article reviews the structure and energetics of the most often found extended defects and describes the mechanisms by which all these defects grow in size and transform during annealing. Defects grow by interchanging the Si atoms they are composed of and thus maintain large supersaturations of free Si interstitials in the region. A model has been developped to describe such an evolution in presence of a free surface. It is shown that after low energy implantation, the surface of the wafer may recombine large amounts of these free Si interstitials, driving defects into dissolution before transformation into more stable forms. Received: 21 August 2002 / Accepted: 21 August 2002 / Published online: 12 February 2003 RID="*" ID="*"Corresponding author. Fax: +33-56/2257-999, E-mail: claverie@cemes.fr