A convenient synthesis of alkyl-2-(2-imino-4-oxothiazolidin-5-ylidene)acetate derivatives involving an electrogenerated base of acetonitrile

We report a simple method for the synthesis of alkyl-2-(2-imino-4-oxothiazolidin-5-ylidene) acetate derivatives 3 in good yields under mild conditions. The electrogenerated cyanomethyl base (EGB), obtained from electroreduction of acetonitrile-0.1?M TBABF₄, assists the reaction between thiourea derivatives 1 and dialkyl acetylene dicarboxylate 2. The expected products, 3/4, and the structure obtained from X-ray diffraction confirm that the main products are the five-membered heterocycles 3. Furthermore, a mechanism, to explain the reaction pathways, is proposed based on the thermodynamic and kinetic data obtained from quantum calculations.     

Dynamics of viscous slugs fall in dry capillaries

The dynamics of viscous slug fall in vertical dry capillaries is investigated by extending a published model (perfect wetting case) accounting for the film left behind the slug as it falls, and Laplace pressures at both ends of the slug in the momentum balance. The present investigation provides and uses an advancing contact-angle correlation determined based on a published theoretical work. The results are found in excellent agreement with published experimental values for falling slugs. The present model does not require any fitting parameter in the perfect wetting case, and is extended to include the non-perfect wetting case along with the unsteady-state dynamics using the quasi-steady-state approximation.     

Linear dynamics of flexible multibody systems

We consider mechanical systems where the dynamics are partially constrained to prescribed trajectories. An example for such a system is a building crane with a load and the requirement that the load moves on a certain path.Enforcing this condition directly in form of a servo constraint leads to differential-algebraic equations (DAEs) of arbitrarily high index. Typically, the model equations are of index 5, which already poses high regularity conditions. If we relax the servo constraints and consider the system from an optimal control point of view, the strong regularity conditions vanish, and the solution can be obtained by standard techniques.By means of the well-known \(n\)-car example and an overhead crane, the theoretical and expected numerical difficulties of the direct DAE and the alternative modeling approach are illustrated. We show how the formulation of the problem in an optimal control context works and address the solvability of the optimal control system. We discuss that the problematic DAE behavior is still inherent in the optimal control system and show how its evidences depend on the regularization parameters of the optimization.     

Thermal Effects in Evaporation from Binary Liquid Mixtures

Thermal effects are considered assuming a volatile component evaporates from a binary liquid mixture in a very long tube. The work is an extension of the work of Chebbi and Selim (2006 Chebbi, R., and Selim, M. S. (2006). The Stefan problem of evaporation of a volatile component from a binary liquid mixture, Heat Mass Transfer, 42(3), 238–247.[Crossref], [Web of Science ®] , [Google Scholar]) (isothermal case) to include evaporative cooling. A similarity solution is provided for the gas–liquid interface temperature and the temperature profiles in the liquid and gas phases. The analysis accounts for the motion of the gas–liquid interface and shows evaporative cooling as expected. The magnitude of evaporative cooling is found significant when volatility of the volatile component is sufficiently high. The validity of the approximations used in the solution is addressed.     

Thermal Spraying of Bioactive Polymer Coatings for Orthopaedic Applications

Flame sprayed biocompatible polymer coatings, made of biodegradable and non-biodegradable polymers, were investigated as single coatings on titanium and as top coatings on plasma sprayed Hydroxyapatite. Biocompatible polymers can act as drug carriers for localized drug release following implantation. The polymer matrix consisted of a biodegradable polymer, polyhydroxybutyrate 98%/ polyhydroxyvalerate 2% (PHBV) and a non-biodegradable polymer, polymethylmethacrylate (PMMA). Screening tests were performed to determine the suitable range of spraying parameters, followed by a Design of Experiments study to determine the effects of spraying parameters on coating characteristics (thickness, roughness, adhesion, wettability), and to optimize the coating properties accordingly. Coatings characterization showed that optimized flame sprayed biocompatible polymers underwent little chemical degradation, did not produce acidic by-products in vitro, and that cells proliferated well on their surface.     

Geometrically nonlinear analysis of FGM shells using solid-shell element with parabolic shear strain distribution

International Journal of Mechanics and Materials in Design - This paper presents a modified first-order enhanced solid-shell element formulation with an imposed parabolic shear strain distribution...     

The predictive role of body image and anti-fat attitudes on attentional bias toward body area in haptic virtual reality environment

Virtual Reality - Evidence suggests that dissatisfaction with body image in women can be enhanced by exposure to media’s idealized images. The theory of social comparison and the avoidance...     

SIMULTANEOUSLY DEVELOPING LAMINAR FLOW AND HEAT TRANSFER IN THE ENTRANCE REGION OF A CIRCULAR TUBE WITH CONSTANT WALL TEMPERATURE

The developing flow and heat transfer in the entry region of a heated circular tube is analyzed for the case of constant wall temperature. An integral or boundary-layer solution is presented which has a number of advantages over earlier Karman-Pohlhausen integral analyses. Thus, in the present analysis, the velocity and temperature distributions, the local and mean drag coefficients, and the local and mean Nusselt numbers approach their fully-developed values asymptotically. The new analysis is based on the hydrodynamic inlet-filled region concept originally proposed by Ishizawa (1966) and later adopted by Mohanty and Asthana (1978) to flow through a circular tube. This concept is extended to the combined entry-length problem by introducing a thermal transition region, herein called the thermally-filled region, between the thermal inlet boundary-layer region and the thermally fully-developed region. A thermal shape factor is also introduced which ensures smooth transition of all pertinent thermal quantities from the entrance region to the fully-developed region. Results for the variation of the local and mean Nusselt numbers with axial distance along the tube for Pr = 0.1,0.5,0.7,1,5, and 10 are presented. These results agree well with the numerical solutions of Hombeck (1965), Manohar (1969), and Hwang and Sheu (1974) and also with the correlations of Churchill and Ozoe (1973).     

Middle lobe syndrome: apropos of 5 cases

The capacity of embryonic spinal cord tissue in the repair of injured structure of spinal cord has been noted for years. In order to investigate the embryonic spinal cord graft in the repair of motor function of injured spinal cord, the embryonic spinal cord tissue was transplanted to the hemisection cavity in spinal cord in adult rat. One hundred adult Wistar Rats were used to simulate the hemisectional injury of spinal cord by drilling 2-3 mm cavity in lumbar enlargement. Sixty rats were treated with rat embryonic spinal cord tissue grafting while the other forty were chosen as control. The outcome was evaluated according the combined behavioural score (CBS) and motor evoked potential (MEP) in the 1, 2, 4 and 12 weeks. The grafting group was superior to the control as assessed by CBS (P < 0.05), especially within 4 weeks. (P < 0.01). The restoration of the latent peak of early wave(P1, N1) was better in the grafting group, too. This suggested that embryonic spinal cord graft could improve the recovery of motor function of injured spinal cord in adult rat. The effect of the embryonic spinal cord tissue graft might be concerned with its secretion of several kinds of neurotrophic factors, nerve growth factor, nerve transmitted factor, or adjustment of hormone.