Hydrogen storage properties of MgH2 mechanically milled with α and β SiC

To understand the influence of various crystallographic phases on hydrogen storage properties, ball milling of MgH₂ with hexagonal (α) and cubic (β) SiC have been performed. Structural characterization of all samples has been done by X-ray diffraction (XRD) analysis, particle size analysis and scanning electron microscopy (SEM). Investigation of hydrogen desorption properties of prepared nanocomposites has been done using temperature programmed desorption (TPD) technique. Despite the results of structural and morphological characterization of obtained nanocomposites are very similar, TPD spectra show significant differences regarding existence of intermediate temperature peak. In the sample milled with hexagonal SiC this peak originates both from H₂ and H₂O, while in the sample milled with cubic phase it only comes from H₂O. Both samples exhibit low temperature H₂ peak at 385 K.     

Puckering the Planar Landscape of Fragments: Design and Synthesis of a 3D Cyclobutane Fragment Library

Fragment-based drug discovery (FBDD) has a growing need for unique screening libraries. The cyclobutane moiety was identified as an underrepresented yet attractive three-dimensional (3D) scaffold. Synthetic strategies were developed via a key 3-azido-cyclobutanone intermediate, giving potential access to a range of functional groups with accessible growth vectors. A focused set of 33 novel 3D cyclobutane fragments was synthesised, comprising three functionalities: secondary amines, amides, and sulfonamides. This library was designed using Principal Component Analysis (PCA) and an expanded version of the rule of three (RO3), followed by Principal Moment of Inertia (PMI) analysis to achieve both chemical diversity and high 3D character. Cis and trans ring isomers of library members were generated to maximise the shape diversity obtained, while limiting molecular complexity through avoiding enantiomers. Property analyses of the cyclobutane library indicated that it fares favourably against existing synthetic 3D fragment libraries in terms of shape and physicochemical properties.     

A Simple Explicit Equation for the Saturation Temperature of Humid Air

Based on the Clausius‐Clapeyron equation and the ideal gas hypothesis for the gas phase, an explicit equation is derived for the saturation temperature of humid air. In order to account for the real gas effects in the vapor phase, the expression is then modified by using the state equation of a pure water two‐phase (vapor‐liquid) system at equilibrium recommended by Wagner and Pruss. Unlike other equations, it does not require knowledge of the relative humidity. The new equation describes the saturation temperature of humid air as a function of humidity ratio x and system pressure p in the following ranges: 0 < x < 0.2; 0.5 bar < p < 16 bar. As a side product, a simple expression for relative humidity is deduced.     

Experimental design to predict process variables in the preparation of cellulose based sustained release microspheres system loaded with prednisolone-cyclodextrin complex

The purpose of this study was to evolve experimental design, to prepare the sustained release microspheres loaded with prednisolone-hydroxypropyl-β-cyclodextrin complex, and develop a successful mathematical model to predict various characteristics of microspheres. Response surface methodology (RSM) has been employed to develop model equations that correlate process variables such as ethyl cellulose (EC, mg), hydroxypropyl methyl cellulose (HPMC, mg), stirring speed (rpm) and surfactant (%) with the response variables such as entrapment efficiency (%), particle size (μm) and release rate (%) of the drug. The adequacy of model equations is confirmed by ANOVA result. Results as predicted by model equations are in good agreement with that of experimental results. In vitro drug release shows that drug (93%) is released from a check point formulation (CPF 2) over the period of 24 h with a sustained release fashion with Quasi-Fickian kinetics. Surface morphology of microspheres varies with the experimental conditions as evidenced by scanning electron microscopy.     

Vitamin D3 Treatment Alters Thyroid Functional Morphology in Orchidectomized Rat Model of Osteoporosis

Vitamin D plays an essential role in prevention and treatment of osteoporosis. Thyroid hormones, in addition to vitamin D, significantly contribute to regulation of bone remodeling cycle and health. There is currently no data about a possible connection between vitamin D treatment and the thyroid in the context of osteoporosis. Middle-aged Wistar rats were divided into: sham operated (SO), orchidectomized (Orx), and cholecalciferol-treated orchidectomized (Orx + Vit. D₃; 5 µg/kg b.m./day during three weeks) groups (n = 6/group). Concentration of 25(OH)D in serum of the Orx + Vit. D₃ group increased 4 and 3.2 times (p < 0.0001) respectively, compared to Orx and SO group. T_4, TSH, and calcitonin in serum remained unaltered. Vit. D₃ treatment induced changes in thyroid functional morphology that indicate increased utilization of stored colloid and release of thyroid hormones in comparison with hormone synthesis, to maintain hormonal balance. Increased expression of nuclear VDR (p < 0.05) points to direct, TSH independent action of Vit. D on thyrocytes. Strong CYP24A1 immunostaining in C cells suggests its prominent expression in response to Vit. D in this cell subpopulation in orchidectomized rat model of osteoporosis. The indirect effect of Vit. D on bone, through fine regulation of thyroid function, is small.     

Optimization of energy consumption in buildings with hydronic heating systems considering thermal comfort by use of computer-based tools

The paper deals with an optimization of parameters, which influence the energy and investment cost as well as the thermal comfort. The parameters considered in this study are: the insulation thickness of the building envelope, the supply-water temperature and the heat exchange area of the radiators. A combination of the building energy simulation software EnergyPlus ¹ and the generic optimization program GenOpt (see footnote 1) has been used for this purpose. The paper presents the application of a one-objective optimization algorithm solving the problems with two objectives, because the optimization algorithm is one-objective and the problem has two objectives, which are minimal total costs and satisfied thermal comfort. The total costs represent the sum of energy consumption and the investment costs. The thermal comfort is represented by Predicted Percentage of Dissatisfied (PPD) in this study. The optimization is used to determine the values of parameters that give the lowest sum of investment and energy cost, under the condition that the thermal comfort is satisfied. In addition, the optimization processes show the mutual influence of parameters on both the total cost and the thermal comfort.     

Texture profile analysis of bioadhesive polymeric semisolids: Mechanical characterization and investigation of interactions between formulation components

This study reports the use of texture profile analysis (TPA) to mechanically characterize polymeric, pharmaceutical semisolids containing at least one bioadhesive polymer and to determine interactions between formulation components. The hardness, adhesiveness, force per unit time required for compression (compressibility), and elasticity of polymeric, pharmaceutical semisolids containing polycarbophil (1 or 5% w/w), polyvinylpyrrolidone (3 or 5% w/w), and hydroxyethylcellulose (3, 5, or 10% w/w) in phosphate buffer (pH 6.8) were determined using a texture analyzer in the TPA mode (compression depth 15 mm, compression rate 8 mm s⁻¹, 15 s delay period). Increasing concentrations of polycarbophil, polyvinylpyrrolidone, and hydroxyethylcellulose significantly increased product hardness, adhesiveness, and compressibility but decreased product elasticity. Statistically, interactions between polymeric formulation components were observed within the experimental design and were probably due to relative differences in the physical states of polyvinylpyrrolidone and polycarbophil in the formulations, i.e., dispersed/dissolved and unswollen/swollen, respectively. Increased product hardness and compressibility were possibly due to the effects of hydroxyethylcellulose, polyvinylpyrrolidone, and polycarbophil on the viscosity of the formulations. Increased adhesiveness was related to the concentration and, more importantly, to the physical state of polycarbophil. Decreased product elasticity was due to the increased semisolid nature of the product. TPA is a rapid, straightforward analytical technique that may be applied to the mechanical characterization of polymeric, pharmaceutical semisolids. It provides a convenient means to rapidly identify physicochemical interactions between formulation components. © 1996 John Wiley & Sons, Inc.     

Effect of Thermal Asymmetry on Laminar Forced Convection Heat Transfer in a Porous Annular Channel

The effect of thermal asymmetry on laminar forced convection heat transfer in an annular porous channel with a Darcy dissipation of fluid kinetic energy was investigated numerically. The cylindrical surfaces making the channel boundaries were kept at constant but different temperatures. The thermal asymmetry thus imposed on the system results in an asymmetric temperature field and different heat fluxes across the channel boundaries. Depending on the Darcy, Péclet and Reynolds numbers, the thermal asymmetry may lead to a reversal of the heat flux along the channel at least at one of the channel walls. The corresponding Nusselt number becomes zero and subsequently experiences a discontinuity, thereby jumping from infinite negative to infinite positive, or vice versa. This feature is observed in the region of thermal development. In the fully developed heat transfer region, the Nusselt numbers can be positive or negative for the same inlet conditions, depending on the heat source strength. In the case of a plug flow, the analytical expressions for the Nusselt numbers have been obtained.     

Supporting collaborative learning and problem-solving in a constraint-based CSCL environment for UML class diagrams

We present COLLECT-UML, a constraint-based intelligent tutoring system (ITS) that teaches object-oriented analysis and design using Unified Modelling Language (UML). UML is easily the most popular object-oriented modelling technology in current practice. While teaching how to design UML class diagrams, COLLECT-UML also provides feedback on collaboration. Being one of constraint-based tutors, COLLECT-UML represents the domain knowledge as a set of constraints. However, it is the first system to also represent a higher-level skill such as collaboration using the same formalism. We started by developing a single-user ITS that supported students in learning UML class diagrams. The system was evaluated in a real classroom, and the results showed that students’ performance increased significantly. In this paper, we present our experiences in extending the system to provide support for collaboration as well as domain-level support. We describe the architecture, interface and support for collaboration in the new, multi-user system. The effectiveness of the system has been evaluated in two studies. In addition to improved problem-solving skills, the participants both acquired declarative knowledge about effective collaboration and did collaborate more effectively. The participants have enjoyed working with the system and found it a valuable asset to their learning.     

Does individual treatment for alcoholic fathers benefit their children? A longitudinal assessment.

Psychosocial adjustment in children of alcoholics (COAs; N = 125) was examined before and at 3 follow-ups in the 15 months after their fathers entered alcoholism treatment. Before their fathers' treatment, COAs exhibited greater overall and clinical-level symptomatology than children from the demographically matched comparison sample, but they improved significantly following their fathers' treatment. Children of stably remitted fathers were similar to their demographic counterparts from the comparison sample and had fewer adjustment problems than children of relapsed fathers, even after accounting for children's baseline adjustment. Thus, COAs' adjustment improved when their fathers received treatment for alcoholism, and fathers' recovery from alcoholism was associated with clinically significant reductions in child problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)