One-step synthesis,characterization and oxidative desulfurization of 12-tungstophosphoric heteropolyanions immobilized on amino functionalized SBA-15

Keggin-type 12-tungstophosphoric [PW₁₂O₄₀]^3? heteropolyanions were successfully immobilized onto mesoporous material surface of SBA-15 functionalized using the (3-aminopropyl)triethoxysilane (APTES) synthesized by one-pot co-condensation method, also called one-step synthesis. The synthesized PW^?-NH₃⁺-SBA-15 catalyst was characterized by XRD, N₂ adsorption–desorption, FT-IR, TGA, SEM, TEM, EDS, XPS methods. The results indicated that ordered hexagonal mesostructure for SBA-15 support was still maintained after being functionalized with amine groups, while the specific surface area of SBA-15 was decreased. The active species of phosphotungstic acid H₃PW₁₂O₄₀ (HPW) retained its Keggin structure of the heteropolyanions on the amine-modified SBA-15. The PW^?–⁺H₃N–SBA–15 catalyst exhibited a high catalytic activity for oxidative desulfurization process of sulfur-containing model fuel. The dibenzothiophene (DBT) conversion of almost 100% was achieved with reaction conditions of 40?mg of catalyst dosage, 2?mL of hydrogen peroxide, 90?°C of reaction temperature, and 120?min of reaction time.     

Effects of pulse reverse electroforming parameters on the thickness uniformity of electroformed copper foil

The non-uniformity of electroformed layers directly affects the mechanical properties and application requirements of micro devices. Therefore, uniformity of electroformed copper foil is significant in ensuring or improving the mechanical properties of micro devices. The influences of duty cycle, current density, power source, and electroforming time on the thickness uniformity of electroformed copper layers were studied, and these parameters were optimised by using the orthogonal experiment method. The thickness distribution rule of electroformed copper foil was also determined. Duty cycle had the largest influence on the uniformity; the uniformity of electroformed layers prepared with pulse reverse current power source was superior to those prepared with direct current power source and pulse current power source. Increasing current density enhanced uniformity. The optimal technical process suggested by this orthogonal experiment adopts pulse reverse current power, 30% of positive duty cycle, 10% of negative duty cycle, 2?A?dm^?2 of current density, and 92?minutes of electroforming time. The minimum coefficient of variation reached 1.54%. The thickness of electroformed copper foil varied directionally.     

Residual stresses in press-braked stainless steel sections,I: Coiling and uncoiling of sheets

The manufacturing process of cold-formed thin-walled steel members induces cold work which can be characterized by the co-existent residual stresses and equivalent plastic strains and has a significant effect on their structural behaviour and strength. The present paper and the companion paper are concerned with the prediction of residual stresses and co-existent equivalent plastic strains in stainless steel sections formed by the press-braking method. This manufacturing process consists of the following two distinct stages: (i) coiling and uncoiling of the sheets, and (ii) press-braking operations. This paper presents an analytical solution for the residual stresses and co-existent equivalent plastic strains that arise from the first stage. In the analytical solution, the coiling–uncoiling stage is modelled as an inelastic plane strain pure bending problem; the stainless steel sheets are assumed to obey Hill’s anisotropic yield criterion with isotropic hardening to account for the effects of material anisotropy and nonlinear stress–strain behaviour. The accuracy of the solution is demonstrated by comparing its predictions with those obtained from a finite element analysis. The present analytical solution and the corresponding analytical solution for press-braking operations presented in the companion paper form an integrated analytical model for predicting residual stresses and equivalent plastic strains in press-braked stainless steel sections.     

The effects of strength models in numerical study of metal plate destruction by contact explosive charge

Based on a complete mathematical model, the authors set up a problem of metal plate destruction by contacting explosive charge in highly nonlinear dynamic software AUTODYN and solved in two cases using the Johnson–Cook and von Mises strength models. The numerical simulation results were compared with the experimental results and showed a good fit of numerical calculations versus experiments by using the von Mises strength model. The study also shows that the Johnson–Cook strength model, if applied unreasonably, will lead to large errors, which would help to avoid mistakes in the future high speed impact study.     

Ice Thrust in Reservoirs

We undertook a three-year program to measure the magnitude of static ice forces in four reservoirs located in central and northern Quebec. These static forces may be generated by a temperature change or may arise from such other mechanisms as water level variations, wind, and current drag force. Field observations have revealed two important facts: (1) ice covers have circumferential cracks caused either by water level variations or thermal contraction, and (2) the static ice forces are, in some instances, sufficient to trigger an instability of the broken ice covers by buckling. Noting that an ice cover cannot transmit a force to a structure larger than its own resistance, we derive an upper bound for static forces by determining the in-plane compression force at which a fragmented ice cover collapses. Empirical formulas are presented for three typical structure shapes: retaining walls, sluice gates, and piers. These formulas correlate well with the field data collected from the four dam sites, and suggest that the maximum ice thrust may simply be defined as a function of ice thickness and contact geometry.     

An area model for on-chip memories and its application

An area model suitable for comparing data buffers of different organizations (e.g. caches versus register files) and arbitrary sizes is described. The area model considers the supplied bandwidth of a memory cell and includes such buffer overhead as control logic, driver logic and tag storage. The model gave less than 10% error when verified against real caches and register files. It is shown that, comparing caches and register files in terms of area for the same storage capacity, caches generally occupy more area per bit than register files for small caches because the overhead dominates the cache area at these sizes. For larger caches, the smaller storage cells in the cache provide a smaller total cache area per bit than the register set. Studying cache performance (traffic ratio) as a function of area, it is shown that, for small caches (less than the area occupied by 256 registers bits-r.b.e.-or 32 b), direct-mapped caches perform significantly better than four-way set-associative caches and, for caches of medium areas (between 256 r.b.e. and 4096 r.b.e.), both direct-mapped and set-associative caches perform better than fully associative caches     

Analyzing the ranking method for L–R fuzzy numbers based on deviation degree

Ranking fuzzy numbers based on their left and right deviation degree (L–R deviation degree) has attracted the attention of many scholars recently, yet most of their ranking methods have two systematic shortcomings that are usually ignored. This paper addresses these shortcomings and proves them through mathematical proofs instead of providing counter-examples. Applying our analyses will help other authors avoid some common errors when building their own ranking index functions. We use Asady’s ranking index function (2010) as an example when we present our arguments and proofs and provide fully detailed analyses of two of the ranking index functions herein. Based on these analyses, an algorithm for detecting inconsistencies in ranking results is proposed, and numerical examples are given to illustrate our arguments.     

Development of a smart handheld surgical tool with tactile feedback

This paper presents a handheld surgical tool adapting a tactile feedback system. The tool consists of a 3-degree-of-freedom (DOF) force sensor and three tactile displays. The sensor is easily embedded in the tool by adopting the capacitive transduction principle. The sensor measures the direction and magnitude of the 3-DOF force applied to the tool tip. The fingertip grasping the tool is stimulated by the tactile display to transmit the contact force information measured by the sensor. The tactile display is actuated by employing a soft actuator technology based on a dielectric elastomer actuator such as a type of electroactive polymer actuator. In this work, a prototype of the tool is designed and fabricated. Its performance is experimentally validated.     

IL-18 is produced by articular chondrocytes and induces proinflammatory and catabolic responses

IL-18, a cytokine originally identified as IFN-gamma-inducing factor, is a member of the IL-1 family of proteins. Because IL-1alpha and IL-1beta are important mediators in the pathogenesis of arthritis, the present study addresses the expression of IL-18 and its role in regulating in articular chondrocytes. IL-18 mRNA was induced by IL-1beta in chondrocytes. Chondrocytes produced the IL-18 precursor and in response to IL-1 stimulation secreted the mature form of IL-18. Studies on IL-18 effects on chondrocytes showed that it inhibits TGF-beta-induced proliferation and enhances nitric oxide production. IL-18 stimulated the expression of several genes in normal human articular chondrocytes including inducible nitric oxide synthase, inducible cyclooxygenase, IL-6, and stromelysin. Gene expression was associated with the synthesis of the corresponding proteins. Treatment of normal human articular cartilage with IL-18 increased the release of glycosaminoglycans. These finding identify IL-18 as a cytokine that regulates chondrocyte responses and contributes to cartilage degradation.