Preparation of Vanadium and Vanadium Oxide Clusters by Means of Inert Gas Aggregation

Vanadium clusters were prepared by the inert gas aggregation technique by evaporating V of high purity. Structural characterization was performed by high-resolution transmission electron microscopy. Apart from vanadium clusters of bcc structures in different orientations, crystalline VO clusters of NaCl structures were observed, which was attributed to the reaction with free oxygen present on the amorphous carbon substrates. The latter could be detected by electron energy-loss spectroscopy. The exposure of the samples to air caused a change to amorphous structures, which re-crystallized under the electron beam. This effect was interpreted as a reaction with water present in the air.     

Surface and interfacial FTIR spectroscopic studies of latexes. IX. The effect of homopolymer and copolymer structures on surfactant mobility in Sty/BA latices

The effects of homopolymer and copolymer compositions and structures in styrene/n-butyl acrylate (Sty/BA) latices on sodium dioctyl sulfosuccinate (SDOSS) surfactant mobility and its preferential concentration at the film–air (F–A) and film–substrate (F–S) interfaces were examined using attenuated total reflectance Fourier transform infrared (ATR FTIR) spectroscopy. It appears that the SDOSS concentration at the F–S interface is highest when the Sty/BA feed ratio is 50/50, and the excess of Sty results in migration of SDOSS surfactant to the F–A interface. This behavior is attributed to the increased glass transition temperature and diminished compatibility between surfactant molecules and copolymer latex. This study also shows that the primary factors that influence exudation to either F–A or F–S interfaces are surface tension of the substrate, glass transition temperature, water flux during coalescence, and compatibility between latex components. © 1995 John Wiley & Sons, Inc.     

Investigation on the electrocatalytic characteristics of SnO_2 electrodes with nanocoating prepared by electrodeposition method

SnO2 electrodes have many advantages in the degradation of toxic or bio-refractory organic wastewater,and SnO2 is a kind of anode material which has the potential to be widely used.Electrocatalytic effi-ciency and service life of Ti\SnO2 electrodes are key factors that can influence its applications.In order to enhance the electrocatalytic characteristics of Ti\SnO2 electrodes,a type of electrocatalytic electrode with nanocoating was prepared by direct current(DC)electrodeposition method and thermal oxidati...     

Morphology of melt crystallized polypropylene in the presence of polyimide fibres

Hot stage optical and scanning electron microscopy were used to study isothermal crystallization of isotactic polypropylene (iPP) in the presence of polyimide (Pl) fibres. Under the same crystallization conditions, the occurrence of transcrystallization depends on the type of fibre used. The transcrystalline interphase has a composed structure, with a characteristic layer adjacent to the fibre surface. The layer is about 1 m thick and has a crosshatched lamellar morphology. At the interface between iPP and the Pl fibre which causes transcrystallization, the nuclei from which the transcrystalline zone grows is observed. The nuclei consist of sheaves of closely packed parallel needleshaped lamellae of uniform thickness. The transcrystallization phenomenon can be explained by the epitaxial crystallization of iPP matrix on the surface fragments (domains) formed by extended chains of Pl fibres. Different abilities of Pl fibres to induce transcrystallization are associated with the superficial morphology of the fibres.Presented in part at the 28th Europhysics Conference on Macromolecular Physics, Transitions in Oligomer and Polymer Systems, 27 September–1 October 1993, Ulm, Germany.     

The Donauspital-Stolzalpe concept (Danube Hospital, Vienna, Austria). Corrective osteotomy with selective labrum surgery following preoperative MRI arthrography

Concomitant pathologies (labral lesions, intra-/extra-osseous ganglia and stress bone marrow edema) in adult residual hip dysplasia (RHD) might influence the outcome of conservative hip surgery. The aim of our prospective clinical study was to assess the value of preoperative MR arthrography in diagnosing concomitant lesions and in making surgical decisions in RHD. The first 37 consecutive patients with a minimum follow-up of 18 months have been analysed. All 37 patients presented RHD with the clinical symptomatology of labral lesions and underwent routine preoperative MRA. According to clinical, radiological and MR arthrographical criteria, these 37 patients were subdivided into four therapeutic subgroups: (1) reorientation of the acetabulum using the T?nnis triple pelvic osteotomy (TPO); (2) intertrochanteric varisation osteotomy (IVO); (3) palliative decompression with only symptomatic partial resection of the torn labrum (PALL); (4) primary total hip replacement (TEP). Based on the preliminary clinical and radiological outcomes of these four subgroups, the following conclusions can be drawn: labral lesions are considered to be a sign of chronic joint instability. Therefore, acetabular malorientation should be corrected by redirectional osteotomy of the acetabulum (TPO-subgroup) even in low grades of RHD if labral lesions are present. "Palliative" labral resections without corrective osteotomy (PALL subgroup) in secondary osteoarthritis due to RHD are definitively obsolete, because they rapidly progress to severe osteoarthritis due to surgically accelerated joint instability. In RHD with highly osteoarthritic hip joints and concomitant lesions, one should not hesitate to perform primary THR even in young patients.     

Linear offset-free Model Predictive Control

This work addresses the problem of offset-free Model Predictive Control (MPC) when tracking an asymptotically constant reference. In the first part, compact and intuitive conditions for offset-free MPC control are introduced by using the arguments of the internal model principle. In the second part, we study the case where the number of measured variables is larger than the number of tracked variables. The plant model is augmented only by as many states as there are tracked variables, and an algorithm which guarantees offset-free tracking is presented. In the last part, offset-free tracking properties for special implementations of MPC schemes are briefly discussed.     

Invariant and dual subtraction games resolving the Duchêne–Rigo conjecture

We prove a recent conjecture of Duchêne and Rigo, stating that every complementary pair of homogeneous Beatty sequences represents the solution to an invariant impartial game. Here invariance means that each available move in a game can be played anywhere inside the game board. In fact, we establish such a result for a wider class of pairs of complementary sequences, and in the process generalize the notion of a subtraction game. Given a pair of complementary sequences $\left(a_n\right)$ and $\left(b_n\right)$ of positive integers, we define a game $G$ by setting $\left\{\{a_n,b_n\}\right\}$ as invariant moves. We then introduce the invariant game $G^{?}$, whose moves are all non-zero $P$-positions of $G$. Provided the set of non-zero $P$-positions of $G^{?}$ equals $\left\{\{a_n,b_n\}\right\}$, this is the desired invariant game. We give sufficient conditions on the initial pair of sequences for this ‘duality’ to hold.     

运用坐标转换法推导土钉拉力的计算公式

依据折线型破坏滑移面假定，分析土钉支护墙的内部稳定，运用坐标转换的方法，由力的权限平衡条件，推导出土钉拉力T＝∑Ti的计算公式。便于运用计算机编程，计算出土钉拉力。     

MPTP 0.1 - System Description

MPTP (Mizar Problems for Theorem Proving) is a system for translating the Mizar Mathematical Library (MML) into untyped first order format suitable for automated theorem provers, allowing generating theorem proving problems corresponding to MML. The first version generates about 30000 problems from complete proofs of Mizar theorems, and about 630000 problems from the simple (one-step) justifications done by the Mizar checker. We describe the design and structure of the system, some limitations, and planned future extensions.