Centroaffine surfaces in -geodesics

For (positive) definite surfaces in there is a canonical choice of a centroaffine normal plane bundle, which induces a centroaffine invariant Ricci-symmetric connection . We classify all surfaces in with planar -geodesics. It turns out that the resulting class of surfaces is umbilical with projectively flat induced connection and flat normal plane bundle.

     

混合序列的一类强大数定律

将独立情形的Wittmann型强大数定律推广到混合序列情形,丰富了混合序列的强极限理论.     

不同电位影响5-硝基吲哚电化学聚合的光谱分析

三氟化硼乙醚+10%乙醚体系中,恒电位(1.23～2.23 V vs.SCE)条件下可以获得高质量聚膜(PNI),这是首次获得硝基取代高性能导电高分子膜材料。5-硝基吲哚(NI)的起始氧化电位为1.04 V vs.SCE。电流-时间曲线、FTIR和1H NMR结果均表明聚合电位对PNI膜质量有较大影响。低电位有利于NI的聚合,且有利于增加PNI膜的共轭链长;高电位会导致NI的副反应,从而降低PNI膜的质量。同时红外光谱和1H NMR研究表明,NI的电化学聚合是通过2, 3位进行的。     

Anomalous scaling in a non-Gaussian random shell model for passive scalars

In this paper, we have introduced a shell-model of Kraichnan's passive scalar problem. Different from the original problem, the prescribed random velocity field is non-Gaussian and $\delta$ correlated in time, and its introduction is inspired by She and L\'{e}v\^{e}que (Phys. Rev. Lett. {\bf 72}, 336 (1994)). For comparison, we also give the passive scalar advected by the Gaussian random velocity field. The anomalous scaling exponents $H(p)$ of passive scalar advected by these two kinds of random velocities above are determined for structure function with values of $p$ up to 15 by Monte Carlo simulations of the random shell model, with Gear methods used to solve the stochastic differential equations. We find that the $H(p)$ advected by the non-Gaussian random velocity is not more anomalous than that advected by the Gaussian random velocity. Whether the advecting velocity is non-Gaussian or Gaussian, similar scaling exponents of passive scalar are obtained with the same molecular diffusivity.     

瓜环与喹啉衍生物包结配合行为研究

利用¹H NMR以及荧光技术研究了六、七、八元瓜环与2-苯基喹啉、N-正丙基溴化异喹啉、3-氨基喹啉及7,8-苯并喹啉的相互作用.两种方法的考察结果均表明,2-苯基喹啉能与这3种瓜环发生相互作用,其中六、七元瓜环与2-苯基喹啉形成1∶1的稳定包结配合物,包结常数分别为1.6×10⁴和3.2×10³L/mol.八元瓜环能与2-苯基喹啉形成1∶2包结物.¹H NMR结果还表明,3种瓜环均能与N-正丙基溴化异喹啉相互作用,其化学计量比均为1∶2;七元瓜环与7,8-苯并喹啉相互作用,化学计量比约为1∶1.荧光法也表明八元瓜环能与N-正丙基溴化异喹啉、3-氨基喹啉及7,8-苯并喹啉发生相互作用,并且荧光强度随瓜环浓度增加而下降,其化学计量比为1∶2.同时,讨论了上述主客体包结配合物的作用模式.     

Shelah's strong covering property and CH in V[r]

In this paper we review Shelah's strong covering property and its applications. We also extend some of the results of Shelah and Woodin on the failure of $\mathsf {CH}$ by adding a real.     

Regional variations in MR relaxation of hip joint cartilage in subjects with and without femoralacetabular impingement

The objective of this study was to analyze regional variations of magnetic resonance (MR) relaxation times (T_1ρ and T₂) in hip joint cartilage of healthy volunteers and subjects with femoral acetabular impingement (FAI). Morphological and quantitative images of the hip joints of 12 healthy volunteers and 9 FAI patients were obtained using a 3 T MR scanner. Both femoral and acetabular cartilage layers in each joint were semi-automatically segmented on sagittal 3D high-resolution spoiled gradient echo (SPGR) images. These segmented regions of interest (ROIs) were automatically divided radially into twelve equal sub-regions (30⁰ intervals) based on the fitted center of the femur head. The mean value of T_1ρ/T₂ was calculated in each sub-region after superimposing the divided cartilage contours on the MR relaxation (T_1ρ/T₂) maps to quantify the relaxation times. T_1ρ and T₂ relaxation times of the femoral cartilage were significantly higher in FAI subjects compared to healthy controls (39.9 ± 3.3 msec in FAI vs. 35.4 ± 2.3 msec in controls for T_1ρ (P = 0.0020); 33.9 ± 3.1 msec in FAI vs. 31.1 ± 1.7 msec in controls for T₂ (P = 0.0160)). Sub-regional analysis showed significantly different T_1ρ and T₂ relaxation times in the anterior-superior region (R9) of the hip joint cartilage between subjects with FAI and healthy subjects, suggesting possible regional differences in cartilage matrix composition between these two groups. Receiver operating characteristic (ROC) analysis showed that sub-regional analysis in femoral cartilage was more sensitive in discriminating FAI joint cartilage from that of healthy joints than global analysis of the whole region (T_1ρ: area under the curve (AUC) = 0.981, P = 0.0001 for R9 sub-region; AUC = 0.901, P = 0.002 for whole region; T₂: AUC = 0.976, P = 0.0005 for R9 sub-region; AUC = 0.808, P = 0.0124 for whole region). The results of this study demonstrated regional variations in hip cartilage composition using MR relaxation times (T_1ρ and T₂) and suggested that analysis based on local regions was more sensitive than global measures in subjects with and without FAI.     

Nondifferentiable Multiobjective Programming under Generalized d-ρ-(η,θ)-Type I Univexity

In this paper,on the basis of notions of d-ρ-(η,θ)-invex function,type I function and univex function,we present new classes of generalized d-ρ-(η,θ)-type I univex functions.By using these new concepts,we obtain several sufficient optimality conditions for a feasible solution to be an efficient solution,and derive some Mond-Weir type duality results.     

ρ-混合序列的大数定律和完全收敛性

主要研究了ρ-混合序列的大数定律和完全收敛性,获得了与ρ-混合序列情形一样的大数定律和完全收敛性．     

Static dissolution rate of tungsten film versus chemical adjustments of a reused slurry for chemical mechanical polishing

Tungsten is widely used as deposited layer for the multi-level interconnection structures of wafers. The chemical composition of abrasive slurry plays an important role in chemical mechanical polishing (CMP) process. Removal of tungsten is driven by complex oxidation mechanisms between slurry components. The slurry for tungsten CMP generally contains oxidizer, iron catalyst, complexing agents and stabilizers in a pH adjusted solution of abrasive particles. Interaction between iron complex and H₂O₂ in the slurry is the main factor governing the chemical mode of material removal, oxidation potencies and kinetics.In this study, we investigate the effects of chemical additives in silica (SiO₂)-based slurry on the removal rate of the tungsten film. Experiments were carried out in static batch as a preliminary study to understand and optimize chemical mechanisms in CMP-Tungsten process. Experiment designs were conducted to understand the influence of the chemical additives on the main performances of W-CMP. Used slurry, concentrated and retreated with chemical adjustments, is compared to the original slurry as a reference.