Chemical composition and bond structure of carbon-nitride films deposited by CH4/N2 dielectric barrier discharge

Carbon nitride films have been deposited by dielectric barrier discharge with a CH₄/N₂ gas mixture at different conditions. Fourier Transform Infrared (FTIR) spectroscopy, X-ray photo electron spectroscopy (XPS), Raman spectroscopy, Atomic force microscopy (AFM) and ellipsometry were used to systematically study chemical composition, bond structure and surface morphology of deposited films. Various bonds between carbon, nitrogen, hydrogen, and also oxygen were observed.     

Hydrolysis of fats and oils with moist oat caryopses

To improve the economic feasibility of hydrolyzing fats and oils with moist oat caryopses, various factors affecting the efficiency of the process were studied. Caryopses produced with an impact-type dehuller exhibited greater lipase activity than those produced by a wringer-type dehuller. Abrasion of oat caryopses against each other in a fluidized bed released particles rich in lipase. Such lipase concentrates could be added to moist caryopsis reactors to speed fat hydrolysis. Beef tallow, lard, soybean oil and crambe oil were hydrolyzed more efficiently than corn oil, castor oil and milk fat. The poor hydrolysis of castor oil was attributed to the formation of esters with the hydroxy group of ricinoleic acid, and the hydrolysis of castor oil was increased by dilution of the substrate with hexane. Diglycerides inhibited the hydrolysis and accounted for the slower hydrolysis of corn oil. Hydrolysis of milk fat by moist oat caryopses resulted in preferential hydrolysis of C₆ to C₁₀ acids. Erucic acid was released from crambe oil at significantly slower rates than the other acyl groups. High conversions of fats and oils to free fatty acids could be attained by (i) exposing the fats and oils to two to three lots of moist caryopses, (ii) the use of special oat varieties with elevated lipase content, (iii) the addition of oat lipase concentrates to moist caryopsis reactors, and (iv) dilution of the substrate with hexane. Estimates of the cost of producing free fatty acids with these processes indicated that the first three should be profitable. Growth ofClostridium sporogenes spores could not be demonstrated in caryopsis reactors. During the incubation of moist oat caryopses immersed in oil, the free fatty acid content of the internal caryopsis lipid increased only slightly, but there were changes in its fatty acid composition.     

Microstructure and properties of flame sprayed tungsten carbide coatings

This article reports on feasibility experiments carried out with oxy-acetylene spray system with various oxygen to fuel ratios using two different tungsten carbide powders and powder feeding methods, to evaluate the newly developed fused WC, synthesised by transferred arc thermal plasma method. Transferred arc thermal plasma method is more economical and less energy intensive than the conventional arc method and results in a fused carbide powder with higher hardness. The microstructure and phase composition of powders and coatings were analysed by optical and scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Carbon content of the powders and coatings were determined to study the decarburisation of the material during spraying process. Coatings were also characterised by their hardness and abrasive wear. The effects of metallurgical transformation and phase content are related to wear performance. The results demonstrate that the powders exhibit various degree of phase transformation during the spray process depending on the type of powder, powder feeding and spray parameters. The carbon loss during the spray process in excess of 45% resulted in reduced hardness and wear resistance of the coatings. Coatings with high amount of WC and W₂C along with FeW₃C showed higher wear resistance. Thus, coatings of high wear resistance can be produced using fused tungsten carbide powder with WC and W₂C phases, which can be economically synthesised by thermal plasma transferred arc method.     

NodeWiz: Fault-tolerant grid information service

Large scale grid computing systems may provide multitudinous services, from different providers, whose quality of service will vary. Moreover, services are deployed and undeployed in the grid with no central coordination. Thus, to find out the most suitable service to fulfill their needs, or to find the most suitable set of resources on which to deploy their services, grid users must resort to a Grid Information Service (GIS). This service allows users to submit rich queries that are normally composed of multiple attributes and range operations. The ability to efficiently execute complex searches in a scalable and reliable way is a key challenge for current GIS designs. Scalability issues are normally dealt with by using peer-to-peer technologies. However, the more reliable peer-to-peer approaches do not cater for rich queries in a natural way. On the other hand, approaches that can easily support these rich queries are less robust in the presence of failures. In this paper we present the design of NodeWiz, a GIS that allows multi-attribute range queries to be performed efficiently in a distributed manner, while maintaining load balance and resilience to failures.     

Uncertainty propagation in puff-based dispersion models using polynomial chaos

Atmospheric dispersion is a complex nonlinear physical process with numerous uncertainties in model parameters, inputs, source parameters, initial and boundary conditions. Accurate propagation of these uncertainties through the dispersion models is crucial for a reliable prediction of the probability distribution of the states and assessment of risk. A simple three-dimensional Gaussian puff-based dispersion model is used as a test case to study the effect of uncertainties in the model parameters and initial conditions on the output concentration. A polynomial chaos based approach is used to numerically investigate the evolution of the model output uncertainties due to initial condition and parametric uncertainties. The polynomial chaos solution is found to be an accurate approximation to ground truth, established by Monte Carlo simulation, while offering an efficient computational approach for large nonlinear systems with a relatively small number of uncertainties.     

Metronidazole-loaded nanostructured lipid carriers to improve skin deposition and retention in the treatment of rosacea

The objective of the present investigation was to improve the skin deposition and retention of metronidazole (MTZ) in rosacea therapy by incorporating it into nanostructured lipid carriers (NLCs). The main challenge in this endeavor was the partial hydrophilicity of MTZ, which mandated careful selection of excipients, including solid and liquid lipids, surfactants, and their ratios in combination. NLCs were produced by the phase inversion temperature method and finally converted into a gel for topical application. The prepared nanoparticles were evaluated for their particle size, zeta potential, entrapment efficiency, solid-state characteristics, surface morphology, in vitro drug release, and permeation through excised skin. The gel was additionally characterized for its pH, drug content, viscosity, and spreadability. The prepared nanoparticles were spherical in shape and of size less than 300?nm. Incorporation of judiciously chosen excipients made possible a relatively high entrapment efficiency of almost 40%. The drug release was found to be biphasic, with an initial burst release followed by sustained release up to 8?hours. In comparison to the plain drug gel, which had a tissue deposition of 11.23%, the NLC gel showed a much superior and desirable deposition of 26.41%. The lipophilic nature of the carrier, its size, and property of occlusion enabled greater amounts of drug to enter and be retained in the skin, simultaneously minimizing permeation through the skin, i.e. systemic exposure. The results of the study suggest that NLCs of anti-rosacea drugs have the potential to be used in the therapy of rosacea.     

Numerical study of heat and moisture transport through concrete at elevated temperatures

This research article focuses on numerical investigation of heat and moisture transport through concrete exposed to high temperatures such as fire. The conservation equations for moisture and energy transport through concrete have been represented in terms of temperature, pore pressure and vapor content as field variables. As the resulting governing equations are coupled and non-linear, the equations were solved numerically using Galerkin’s weighted residual finite element method and an iterative solution technique. After validating the model, a detailed simulation study has been carried out to understand the role of gradients of temperature, pore pressure and vapor content on heat and moisture transport through concrete exposed to ISO 834 fire curve. Results obtained at the end of 30 minutes exposure of concrete show that the temperature gradients become very steep after 12 minutes of exposure of concrete, which in turn results in increased vapor generation and 93% of vapor generation is completed at the end of 20 minutes. Due to steep temperature gradient along the length of concrete, condensation of vapor takes place which is followed by blockage of pores giving rise to sudden peak pore pressure rise and 97% of peak pore pressure is attained at the end of 18 minutes itself. It is observed that for the initial 18 minutes, the peak pore pressure front and peak vapor content front follow the same path and after 18 minutes the peak vapor content front moves slightly ahead of the peak pore pressure front.     

Three dimensional modeling and finite element simulation of a generic end mill

The geometry of cutting flutes and the surfaces of end mills is one of the crucial parameters affecting the quality of the machining in the case of end milling. These are usually represented by two-dimensional models. This paper describes in detail the methodology to model the geometry of a flat end mill in terms of three-dimensional parameters. The geometric definition of the end mill is developed in terms of surface patches; flutes as helicoidal surfaces, the shank as a surface of revolution and the blending surfaces as bicubic Bezier and biparametric sweep surfaces. The proposed model defines the end mill in terms of three-dimensional rotational angles rather than the conventional two dimensional angles. To validate the methodology, the flat end milling cutter is directly rendered in OpenGL environment in terms of three-dimensional parameters. Further, an interface is developed that directly pulls the proposed three-dimensional model defined with the help of parametric equations into a commercial CAD modeling environment. This facilitates a wide range of downstream technological applications. The modeled tool is used for finite element simulations to study the cutting flutes under static and transient dynamic load conditions. The results of stress distribution (von mises stress), translational displacement and deformation are presented for static and transient dynamic analysis for the end mill cutter flute and its body. The method described in this paper offers a simple and intuitive way of generating high-quality end mill models for use in machining process simulations. It can be easily extended to generate other tools without relying on analytical or numerical formulations.