Spreading of Initially Spherical Viscous Droplets

The present work is a study of the low inertia spreading dynamics of initially spherical viscous droplets on a planar interface. The droplets are affected by gravity, surface tension and viscous forces and are modeled as two-dimensional axisymmetric bodies. The main focus of this study is the examination of the dependence of droplet stability, equilibrium shape and fluid motion within the drop on the relative magnitude of these forces. The dynamics are modeled using the unsteady, non-linear Navier-Stokes equations for an incompressible fluid. The spreading of a droplet on a solid surface is modeled with both a no-slip and a partial-slip boundary condition. In addition, the spreading of a droplet on another identical drop (two-drop problem) is modeled to study the problem without the contact point singularity. The governing equations are solved numerically using the Mixed Galerkin Finite Element formulation, augmented by the use of the Newton-Raphson iteration scheme to effectively treat the non-linearities of the problem. The Generalized Eulerian Lagrangian formulation is adopted for the treatment of the moving free surface of the droplet. Computations are performed for capillary numbers ranging from 0.01 to 100 and for Reynolds numbers from 0.005 to 50, where the velocity scale is based on the droplet radius and the gravitational acceleration. For the droplet spreading on a solid surface, three distinct behaviors are observed~: for low Reynolds numbers and sufficiently high capillary numbers, droplets deform to a stable, equilibrium shape; for higher Reynolds numbers, an oscillatory droplet behavior occurs; at still higher Reynolds numbers, the droplets shatter. Very often, a recirculation is induced near the contact point just before the droplet shatters, which is also observed for the case of stable oscillating droplets. When a partial-slip boundary condition is applied, it is observed that the stability of the droplet and the rate at which the droplet attains the static contact angle depend strongly on the velocity of slip of the droplet with respect to the solid surface at the contact point. For the two-drop problem, only two distinct behaviors are observed: for low Reynolds numbers and high capillary numbers, the droplet retains a near-spherical shape and remains stable; while for higher Reynolds numbers, the droplet deforms to a high extent and becomes unstable

Hybrid I&C Grounding in PFBR

Nuclear Power plants require well established grounding scheme  towards personnel safety and smooth control of the  plant.  Combination of Single & Multi point grounding with Faraday cage configuration is followed in Prototype Fast Breeder Reactor (PFBR).  This paper explains the scheme. Keywords: Ground, Shield, Cage, Safet

Development of FPGA Based System for Neutron Flux Monitoring in Fast Breeder Reactors

The project aims to calculate the frequency of the neutron flux by monitoring the signal from neutron detector from shutdown to full power over 10 decades. This neutron flux signal is input to the FPGA based MODULE. A mathematical relationship has been established between the neutron flux (frequency of the neutrons) and the area under the signal. Variable amplitude and occurrence have been accounted for. White noise has also been added and tested for.  VHDL has been used to simplify the otherwise complicated logic gate design. Mathematical modeling has been used as it is the most accurate of the available methods. Index Terms --  Neutron flux monitoring, area, pulse

A Study on Effect of Operating Conditions on Gerotor Pump Performance

One of the important accessories of the lubrication system of an aero-engine is the oil pump which consists of multiple pumps with tandem gerotor elements housed in a single casing. This paper presents the volumetric efficiency variation of a single-stage gerotor pump specially designed for aero-engine by conducting experiments at on and off-design conditions and comparing it with the CFD analysis. A Gerotor pump having fixed geometrical parameters designed based on a  athematical 1D model using MatLab and AMESim is manufactured and tested. Performance evaluation of these pumps for pressure and temperature has been discussed in this paper. Commercial CFD code ANSYS-Fluent with a standard k- ε turbulence model has been used for performance evaluation of gerotor pump. Flow characteristics studies on the prototype pump indicate that simulation results closely matched the experimental data. The study concludes that the simulation method adopted is appropriate for predicting the performance of the gerotor pump and the contribution of outlet pressure to the pump volumetric efficiency is significant

Design of Reinforced Earth Wall Using Pond Ash - A laboratory study

Pond ash produced as a by-product of the coal based thermal plants whose disposal is often a major environmental and economic issue. Reinforced earth wall is preferred over conventional RCC rigid retaining wall as it is not only cost effective but also has better performances during earthquake. But it uses the natural resources sand as the fill material. In this work, a possible use of pond ash and its mixture with sand as a fill material for reinforced earth wall is investigated. The major issue about the use of pond as a fill material is the development of shear resistance or pull out capacity. In this work the shear behaviour of pond ash, sand and its mixture is studied. A polymeric reinforcement is considered and the friction between the polymeric reinforcement and the pond ash mixture is studied using a laboratory pull out test. Experiments have been conducted on a model of the pond ash mix with reinforcement. The results have been compared with the simulation using a finite element based commercial software, PLAXIS 2D

Patterns and Functions of Total Reduplication in Classical Arabic and Modern Standard Arabic:: A Corpus-Based Study

In this paper, we investigate the form, salient patterns and core functions of word-level total reduplication in Classical Arabic (CA) and Modern Standard Arabic (MSA). Using a multi-genre corpus of 469 million words, we extract total reduplication (TR) candidates into an SQL database, manually filter them, and perform concordance search to identify the patterns and functions. Data analysis reveals nine patterns and eleven functions of TR and compares their relative frequency in each variety. The functions of TR are mapped into two broad categories: morphological and semantic/pragmatic. Results show an interesting variation in terms of top functions being favored by the two varieties. While TR is favored by CA to express serial ordering, MSA is noticed to favor it to express intensification. The empirical findings of this study provide a reliable quantification of the status of TR in CA and MSA which is rather difficult to obtain by theoretical means: on the one hand, TR in Arabic is not as productive as in other languages such as Indonesian. On the other hand, it is more common in CA than in MSA because the latter usually resorts to using loose phrases to express the same concepts expressed by TR in CA.In this paper, we investigate the form, salient patterns and core functions of word-level total reduplication in Classical Arabic (CA) and Modern Standard Arabic (MSA). Using a multi-genre corpus of 469 million words, we extract total reduplication (TR) candidates into an SQL database, manually filter them, and perform concordance search to identify the patterns and functions. Data analysis reveals nine patterns and eleven functions of TR and compares their relative frequency in each variety. The functions of TR are mapped into two broad categories: morphological and semantic/pragmatic. Results show an interesting variation in terms of top functions being favored by the two varieties. While TR is favored by CA to express serial ordering, MSA is noticed to favor it to express intensification. The empirical findings of this study provide a reliable quantification of the status of TR in CA and MSA which is rather difficult to obtain by theoretical means: on the one hand, TR in Arabic is not as productive as in other languages such as Indonesian. On the other hand, it is more common in CA than in MSA because the latter usually resorts to using loose phrases to express the same concepts expressed by TR in CA

Tert Promoter Mutations In Melanoma Render Tert Expression Dependent On Mapk Pathway Activation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The mechanism of telomerase re-activation in cancer had remained elusive until the discovery of frequent mutations in the promoter of the TERT gene that encodes the catalytic reverse transcriptase subunit of telomerase. We investigated the regulation of TERT expression in melanoma cell lines and our results show that promoter mutations render TERT expression dependent on MAPK activation due to oncogenic BRAF or NRAS mutations. Mutations in the TERT promoter create binding sites for ETS transcription factors. ETS1, expressed in melanoma cell lines, undergoes activating phosphorylation by ERK at Thr38 residue as a consequence of constitutively activated MAPK pathway. We demonstrate that ETS1 binds on the mutated TERT promoter leading to the re-expression of the gene. The inhibition of ETS1 resulted in reduced TERT expression. We provide evidence that the TERT promoter mutations provide a direct link between TERT expression and MAPK pathway activation due to BRAF or NRAS mutations via the transcription factor ETS1.7335312753136CAPES - Brazilian Federal Agency for Support and Evaluation of Graduate Education within the Ministry of Education of BrazilLigue Contre le Cancer Comite de ParisGEFLUC Paris-Ile-de-FranceFondation ARC pour la Recherche sur le CancerINSERMUniversite Paris DiderotTRANSCAN through German Ministry of Education and Science [01KT1511]Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

INFLUENCE OF POMEGRANATE JUICE ON THE CYP3A4-MEDIATED METABOLISM AND P-GLYCOPROTEIN MEDIATED TRANSPORT OF SAQUINAVIR IN VIVO AND EX VIVO MODELS

Cytochrome P450 3A4 (CYP3A4) and P-glycoprotein (P-gp) play an important role in the first pass metabolism thereby limits the oral bioavailability of many clinically important and frequently prescribed drugs. The absolute oral bioavailability of saquinavir is very low (i. e. 4%) due to its extensive first pass metabolism by the major metabolizing isozyme CYP3A4 and it is also a substrate of P-gp. Pomegranate juice (PGJ) was known to be a modulator of CYP3A4 and P-gp. Therefore, the aim of this study was to evaluate the influence of PGJ on the pharmacokinetics (PK) of saquinavir in wistar rats and on the P-gp mediated intestinal transport of saquinavir in everted gut sacs ex vivo.  Rats were treated orally with saquinavir (100 mg/kg) alone and in combination with PGJ (0.5, 1.0 and 2.0 mL/200g, body weight) for 15 consecutive days. Blood samples were collected on 1st day in single dose pharmacokinetic study (SDS) and on 15th day in multiple dose pharmacokinetic study (MDS). The peak plasma concentration (Cmax)and area under the plasma concentration-time curve (AUC0-24) of saquinavir was increased with PGJ in SDS (p<0.001) may be due to inhibition of CYP3A4 and P-gp. But interestingly, the Cmax and AUC0-24 of saquinavir was decreased significantly with PGJ in MDS. This is may be due to induction of CYP3A4. The transport of saquinavir was increased in presence of PGJ and known P-gp inhibitors (Verapamil, Ketoconazole and Quinindine) across the rat everted gut sacs ex vivo. The present study results suggested that PGJ has both effects (inhibition, in SDS and induction, in MDS) on CYP3A4-mediated saquinavir metabolism in vivo and inhibitory effect on the P-gp mediated intestinal transport of saquinavir ex vivo. Further studies are needed to confirm this interaction at cellular level using cell lines and in humans

A novel conductometric titration approach for rapid determination of boron

21-30In laboratories dealing with radioactive samples it is important to minimize both the sample size and also the associated waste generated in an analysis. To meet this objective a rapid conductometric titration technique is developed to determine boron in the moderators of Pressurized Heavy Water Reactors (PHWR’s). Using this novel PC interfaced titration facility a minimum tenfold reduction in sample size is achieved compared to conventional conductometric titration. Determination of boron is based on the conversion of extremely weak boric acid to better conducting boron mannitol complex and titrating the complex against NaOH. Various parameters affecting the analysis, when moving from large to small sample size, are analyzed and optimized. The technique is primarily proposed for the assay of boron (≥0.5 ppm) during reactor startup. Each analysis requires less than 10 min. The detection limit is 0.5 ppm and the precision obtained at this level is 4.6% RSD. The technique is a good alternative to less sensitive carminic acid based spectrophotometric method

Density, dielectric and X-ray studies of Smectic A-Smectic A transitions

We report here the results of detailed density, dielectric and X-ray studies on three systems exhibiting different types of Smectic A-Smectic A transitions. It is found that although the layer spacing shows marked changes at the transitions, the corresponding density changes are extremely small. In every case studied, the dielectric anisotropy shows a pronounced decrease on going over to the lower temperature smectic A phase. This decrease can be correlated with the structural changes