A STUDY OF SPINLINE DYNAMICS USING ORTHOGONAL COLLOCATION

Previous work on slow flow of non-Newtonian fluids past particles assemblages has been reviewed. Using a combination of Happel's free surface model and variational principles, bounds on the drag have been obtained for the creeping flow of a Carreau Model fluid past an assemblage of rigid spheres. The bounds are related to friction factor for flow through fixed beds of spherical particles. Numerical results covering a wide range of model parameters and bed voidages are presented.

Theoretical predictions are validated by comparing with experimental results reported in the literature that involve viscoelastic fluids. Arithmetic averages of the two bounds compare well for 182 data points with an average error of 12%. It is demonstrated that the present analysis, though based on a purely viscous model, can predict creeping flow behaviour in rigid particles assemblage for both inelastic and viscoelastic fluids.     

Characteristics and wear behavior of cenosphere dispersed titanium matrix composite developed by powder metallurgy route

The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite consists of dispersion of hollow cenosphere particles in α-Ti matrix. The average pore diameter varies from 50 to 150 μm. The presence of porosities is attributed to the damage of cenosphere particles due to the application of load during compaction as well as to the hollow nature of cenospheres. A detailed X-ray diffraction profile of the composites shows the presence of Al₂O₃, SiO₂, TiO₂ and α-Ti. The average microhardness of the composite (matrix) varies from HV 1100 to HV 1800 as compared with HV 240 of the as-received substrate. Wear studies show a significant enhancement in wear resistance against hardened steel ball and WC ball compared with that of commercially available Ti–6Al–4V alloy. The wear mechanism was established and presented in detail. The corrosion behavior of the composites in 3.56% NaCl (mass fraction) solution shows that corrosion potential (φ_corr) shifts towards nobler direction with improvement in pitting corrosion resistance. However, corrosion rate of the cenosphere dispersed Ti matrix composite increases compared with that of the commercially available Ti–6Al–4V alloy.     

Antibacterial activities and corrosion behavior of novel PEO/nanostructured ZrO2 coating on Mg alloy

Plasma electrolytic oxidation (PEO) was developed as a bond coat for air plasma sprayed (APS) nanostructure ZrO₂ as top coat to enhance the corrosion resistance and antibacterial activity of Mg alloy. Corrosion behavior and antibacterial activities of coated and uncoated samples were assessed by electrochemical tests and agar diffusion method toward Escherichia coli (E. coli) bacterial pathogens, respectively. The lowest corrosion current density and the highest charge transfer resistance, phase angle and impedance modulus were observed for PEO/nano-ZrO₂ coated sample compared with those of PEO coated and bare Mg alloys. Nano-ZrO₂ top coat which has completely sealed PEO bond coat is able to considerably delay aggressive ions transportation towards Mg alloy surface and significantly enhances corrosion resistance of Mg alloy in simulated body fluid (SBF) solution. Moreover, higher antibacterial activity was also observed in PEO/nano-ZrO₂ coating against bacterial strains than that of the PEO coated and bare Mg alloys. This observation was attributed to the presence of ZrO₂ nanoparticles which decelerate E. coli growth as a result of E. coli membranes.     

Experimental Validation of Thermal Analysis of Solar Still with Dye

A simple straight forward transient analysis of a single basin solar still has been presented by incorporating the effect of presence of dye and attenuation of solar flux with depth in the water mass of the basin. An explicit expression for water and glass temperature, hourly yield and efficiency of solar still have been derived. Effect of various parameters viz temperature dependence of internal heat transfer coefficients, water depth, absorptivity of water mass and basin liner have been discussed in detail. An experiment has been conducted to validate the theoretical results obtained by present theory. It is concluded that

(i) there is a good agreement between theoretical results and experimental observation for 0.02 m water depth.

(ii) there is a significant effect of dye at larger depth which is in accordance with the experimental observation obtained by Sodha et al.(1.)     

DISPERSION OF MATTER IN FLOW OF A BINGHAM PLASTIC IN A TUBE

The paper is concerned with the dispersion of a solute in a Bingham plastic fluid flowing in a pipe or a parallel plate channel. For pipe flow, the dispersion coefficient K ₂ first increases with ξ₀ (the dimensionless radius of the plug flow region), reaches a maximum and then decreases. But in a channel flow, K ₂ decreases monotonically with increasing ξ₀. Further K ₂ for channel flow is found to be larger than that for pipe flow for all values of ξ₀ except 0.8≤ξ₀≤1.     

A robust and secure watermarking scheme based on singular values replacement

Digital watermarking is an application associated with copyright protection. Any digital object can be used as a carrier to carry information. If the information is related to object then it is known as a watermark which can be visible or invisible. In the era of digital information, there are multiple danger zones like copyright and integrity violations, of digital object. In case of any dispute during rights violation, content creator can prove ownership by recovering the watermark. Two most important prerequisites for an efficient watermarking scheme are robustness and security. Watermark must be robust and recoverable even if a part of content is altered by one or more attacks like compression, filtering, geometric distortions, resizing, etc. In this work, we propose a blind watermarking scheme based on the discrete wavelet transform (DWT) and singular value decomposition (SVD). Singular values (SV??s) of high frequency (HH) band are used to optimize perceptual transparency and robustness constraints. Although most of the SVD-based schemes prove to be robust, little attention has been paid to their security aspect. Therefore, we introduce a signature-based authentication mechanism at the decoder to improve security. Resulting blind watermarking scheme is secure and robust.     

Cardioprotective potential of curcumin against norepinephrine‐induced cell death: a microscopic study

Cardiomyopathy and associated heart failure continues to be one of the most severe complications that threaten a large population. Curcumin, one of the three curcuminoids of the spice turmeric, is very well known for a multitude of health benefits and functions. Norepinephrine (NE), a catecholamine and also a stress hormone may cause the cardiomyocytes to develop increased sensitivity to death with its increasing concentrations. In this study, we investigated the cardioprotective effect of curcumin in NE‐induced cardiac apoptosis using several fluorescent and nonfluorescent microscopic techniques like DAPI, PI, Giemsa, PicroSirius and TUNEL. The aim of the study was to assess the effect of curcumin in preventing the occurrence of features underlying apoptosis such as nuclear disruption, chromatin condensation, DNA fragmentation and alterations in mitochondrial membrane permeability. Our results show that curcumin protects the cardiomyocytes against apoptosis significantly and also helps them to revert to their normal physiological state. Hence, we propose that curcumin has the potential to act as a therapeutic agent for the attenuation of NE‐induced cardiac cell death and modulation of apoptosis in H9c2 cardiomyocytes.     

Insight into 5-aminolevulinic acid-induced modulation of cellular antioxidant metabolism to confer salinity and drought tolerance in maize

The current study investigated the comparative oxidative damage in two maize seedlings induced by saline, drought,and combined stress and the ameliorative role of two different doses (20 and 80 µM) of 5-aminolevulinic acid (ALA) againstthe above-mentioned stresses. Hydroponically grown 10-day-old maize (Zea mays, var. BARI Hybrid Maize-7 (BHM-7) andBARI Hybrid Maize-9 (BHM-9)) seedlings were exposed to 12 dS/m of saline solution, 200 mM mannitol-induced droughtstress alone and their combined stress for 7 days. Result revealed that individual stresses retard the plant growth to somedegrees; however, their combined stress has more detrimental effects, which might be correlated with lipid peroxidation(MDA)-induced oxidative stress in seedlings, enhanced Na⁺/K⁺ ratio, and augmented generation of superoxide (O₂^•−) andhydrogen peroxide (H₂O₂). In contrast, exogenous ALA supplementation at 20 µM concentration markedly recoveredfrom chlorosis and growth inhibition, substantially scavenged reactive oxygen species (ROS) and MDA by preserving ionhomeostasis and relaxing oxidative stress; also, by boosting catalase (CAT) and glutathione S-transferase (GST), andexclusively via depressing the activity of lipoxygenase (LOX) antioxidant enzyme. On the contrary, 80 µM ALA madethings worse; nevertheless, higher activities shown by other antioxidant enzymes; like, superoxide dismutase (SOD),ascorbate peroxidase (APX), peroxidase (POD), and glutathione peroxidase (GPX), which were related to lessen theoxidative damage by highly produced O₂^•− and H₂O₂ under combined stress. Non-denaturing gel electrophoresiswas done for further confirmation. However, ALA importantly increased the photosynthetic pigment contents inboth genotypes irrespective of doses. Nevertheless, GST might have assisted the plants to escape from the herbicidaleffect by detoxification. However, in the combined stress condition, high ALA concentration may have somepositive role to play. Our findings also showed that BHM-9 performed better than BHM-7. Therefore, ALA atlower concentration was effective for single stress of saline and drought, while higher concentration can improveplant survival under combined stress.     

Plasma production and preliminary results from the ADITYA Upgrade tokamak

The Ohmically heated circular limiter tokamak ADITYA (R0 =75 cm,a =25 cm) has been upgraded to a tokamak named the ADITYA Upgrade (ADITYA-U) with an open divertor configuration with divertor plates.The main goal of ADITYA-U is to carry out dedicated experiments relevant for bigger fusion machines including ITER,such as the generation and control of runaway electrons,disruption prediction,and mitigation studies,along with an improvement in confinement with shaped plasma.The ADITYA tokamak was dismantled and the assembly of ADITYA-U was completed in March 2016.Integration of subsystems like data acquisition and remote operation along with plasma production and preliminary plasma characterization of ADITYA-U plasmas are presented in this paper.