Properties of novel CVD graphite fibers and their bromine intercalation compounds

A hybrid fiber with a PAN core surrounded by a vapor grown carbon fiber (VGCF) sheath was fabricated using a proprietary process. The density, ultimate tensile strength, Young's modulus, and resistivity of pristine and bromine intercalated fibers made by this technique having diameters varying from 5 to 50 microns were compared with the values predicted from the rule of mixtures model. For both the pristine and intercalated fibers, the density, ultimate tensile strength, and Young's modulus of the fibers were lower than predicted, but the resistivity was measured to be consistent with predictions. The lower than theoretical mechanical properties may be evidence of a low density disordered interface between the core and the sheath which would lower the density and degrade the mechanical properties, but would leave the resistivity nearly unaffected. Intercalation had little if any effect on the ultimate tensile strength and Young's modulus, but raised the density by about 11 pct., and lowered the resistivity by an order of magnitude. The diameter dependence of the resistivity showed evidence of a depletion layer of the type found in VGCF

Effects of windblown dust on photovoltaic surface s on Mars

Photovoltaic (PV) coverslip material was subjected to Maritan dust storm conditions using basaltic dust flowing through the Martian Surface Wind Tunnel at NASA-Ames. Initially dusted and clear coverslips were held at angles from 0 to 90 deg., and the dust laden wind velocity was varied from 20 to 97 m/s. Blowing dust was found to adhere more to the coverslips as the angle was increased. However, dust was partially cleared from surfaces that were initially dusted at substantially lower velocities in dust laden wind than in clear wind. Thus, an equilibrium amount of dust accumulated which was dependent only upon angle and wind velocity and not upon initial concentration of dust. Abrasion was also evident in the coverslips. It increased with wind velocity and angle of attack. It appears that an initial dust layer may help to protect PV surfaces from abrasion

Factors Affecting Grid-independent Results for Compartment Fire Modelling

Obtaining grid independent results for compartment fires using a computational fluid dynamics (CFD) model is a major challenge, especially when the fire is not prescribed. While simulating a fire scenario using a CFD model, most fire safety engineers use computational cell sizes that can only be supported by their computing resources which may lead to a large error. This paper presents a systematic study to obtain a grid independent result from CFD simulations of an ISO 9705 room fire experiment using the CFD package Fire Dynamics Simulator (FDS) which incorporates a large eddy simulation (LES) methodology along with a mixture fraction combustion model. The experiment involved ignition of two trays of liquid fuel placed in the room and the growth and development of this fire. The study shows that initially as the grid sizes decrease the size of the fire increases and then the fire size starts decreasing to an asymptotic value as the grid sizes decreases further. A discussion is presented on the factors in relation to “goodness” of the grid resolution such as the changing trend of characteristic fire diameters, the size of computational cells etc

PREPARATION AND EVALUATION OF EXTENDED RELEASE NIMESULIDE TABLET BASED ON DIFFUSION CONTROLLED MECHANISM

Now a days the concept of controlled release is quiet popular amongst the formulation scientists. The aim of thisstudy was to develop a once-daily sustained release matrix tablet of Nimesulide using hydroxyl propylmethylcellulose (HPMC K4M) as release controlling factor and to evaluate drug release parameters as per variousrelease kinetic models. The tablets were prepared using wet granulation method. Total of five batches were preparedfrom which two selected batches were further evaluated. Different dissolution models were applied to drug releasedata in order to evaluate release mechanisms and kinetics. The “n” Value of both batches indicates that the drugrelease mechanism follows “Anomalous Transport”. From all these data it is quite clear that batch F2 is optimized asits release kinetic was found to be as per Korsmeyer Peppas model rather than first order of F4

Fast dispersible tablet of paroxetine hydrochloride: taste masking and administration in depressed patients

The bitter taste of paroxetine hydrochloride was masked by complexation with beta cyclodextrin. Complexation of paroxetine hydrochloride with beta cyclodextrin was characterized by differential scanning calorimetry and X-ray powder diffraction. The taste masked complex was directly compressed into tablets using povidone Cl as a super-disintegrant along with other excipients which aid in further improvement of taste. The prepared tablets containing the taste masked complex were evaluated for taste by both in vitro release profile and through panel testing. The taste masked tablets were administered to actual patients by mixing with juices to study weather the patients identifies the presence of medicine in the juices. The results of this study were satisfactory.Colegio de Farmacéuticos de la Provincia de Buenos Aire

The effect of irrigating solutions on the hydration of tricalcium silicate cements: an in vitro study

Background: Calcium silicate cements are hydraulic cements, routinely used for perforation repairs. During such repairs, these cements are invariably exposed to irrigating solutions. Aim: This study aimed to understand the effect of irrigating solutions on the hydration of calcium silicate cements.  Materials and Methods: Sixty extracted teeth were taken and horizontal sections of 2mm were obtained. These samples were randomly divided into two groups viz. Biodentine and BioMTA Plus groups later these cements were condensed into the canal spaces and allowed to set until their setting time. These samples were further subdivided and allowed to encounter three irrigating solutions viz. Normal saline, 17% EDTA, and 2% Chlorhexidine for 5 minutes. These were allowed to mature in an incubator for seven days and subjected to Scanning Electron Microscopy and Energy Dispersive X-ray analysis. Results: The SEM analysis of the Biodentine/control group displayed a petal-like appearance, with a Ca/Si ratio of 2. Whereas, the Biodentine/Normal saline, Biodentine/17% EDTA and Biodentine/2% Chlorhexidine group displayed crumbled paper-like appearance. The Ca/Si ratios for the Biodentine/Normal saline, Biodentine/17% EDTA and Biodentine/2% Chlorhexidine were 2.72, 1.6, and 4.21, respectively. In the BioMTA Plus group, all the SEM analyses displayed round crystalline structures in all groups. The Ca/Si ratio of BioMTA Plus/Control, BioMTA Plus/17% EDTA and BioMTA Plus/2% Chlorhexidine were 25.5, 17.42, 24.1, and 39.4, respectively. Conclusion: The study concluded that the irrigating solutions did not affect the hydration mechanism of Biodentine and BioMTA Plus despite the variations in the Ca/Si ratios and surface morphology

Atlas construction and spatial normalisation to facilitate radiation-induced late effects research in childhood cancer

Reducing radiation-induced side effects is one of the most important challenges in paediatric cancer treatment. Recently, there has been growing interest in using spatial normalisation to enable voxel-based analysis of radiation-induced toxicities in a variety of patient groups. The need to consider three-dimensional distribution of doses, rather than dose-volume histograms, is desirable but not yet explored in paediatric populations. In this paper, we investigate the feasibility of atlas construction and spatial normalisation in paediatric radiotherapy. We used planning computed tomography (CT) scans from twenty paediatric patients historically treated with craniospinal irradiation to generate a template CT that is suitable for spatial normalisation. This childhood cancer population representative template was constructed using groupwise image registration. An independent set of 53 subjects from a variety of childhood malignancies was then used to assess the quality of the propagation of new subjects to this common reference space using deformable image registration (i.e., spatial normalisation). The method was evaluated in terms of overall image similarity metrics, contour similarity and preservation of dose-volume properties. After spatial normalisation, we report a dice similarity coefficient of 0.95±0.05, 0.85±0.04, 0.96±0.01, 0.91±0.03, 0.83±0.06 and 0.65±0.16 for brain and spinal canal, ocular globes, lungs, liver, kidneys and bladder. We then demonstrated the potential advantages of an atlas-based approach to study the risk of second malignant neoplasms after radiotherapy. Our findings indicate satisfactory mapping between a heterogeneous group of patients and the template CT. The poorest performance was for organs in the abdominal and pelvic region, likely due to respiratory and physiological motion and to the highly deformable nature of abdominal organs. More specialised algorithms should be explored in the future to improve mapping in these regions. This study is the first step toward voxel-based analysis in radiation-induced toxicities following paediatric radiotherapy