Stability of magnetohydrodynamic stratified shear flows

Summary A study is made of the stability of a stratified shear flow in a perfectly conducting fluid in the presence of an external magnetic field aligned with the flow. A semi-circle theorem for the present hydromagnetic case is proved. The magnetic field is found to have a stabilizing effect on the flow. The Rayleigh-Taylor instability problem in a stratified conducting fluid is discussed. Finally, a study is made of the absorption of wave energy by the mean flow in the hydromagnetic case by considering a shear flow with an anti-symmetric velocity profile given byU=tanhz. Unlike the hydrodynamic case, it is found that, in the critical layer atU=0, the transfer of the wave energy to the mean flow occurs for any value of the Richardson number. This result implies again the stabilizing effect of the magnetic field on the shear flow.     

Synthesis and characterization of niobium-doped potassium tetragonal tungsten bronzes, KxNbyW1?yO3

Needle-shaped crystals of sizes up to 5 μm × 5 μm × 40 μm of nominal composition K _x Nb _y W_1−y O₃ were synthesized by solid state method at 800 °C using appropriate amount of WO₃, WO₂, Nb₂O₅, and K₂WO₄. The samples were characterized with XRD, SEM, microprobe analysis, optical spectroscopy, and Raman spectroscopy. The XRD patterns of the samples show single phase of tetragonal tungsten bronze (TTB) type (P4/mbm, No. 127) up to y = 0.07. Structure refinements reveal an increase in cell parameter with increasing nominal niobium content within the TTB phase. The elemental compositions of the crystals determined by electron microprobe analysis also show an increase in Nb content with increasing y. With increasing Nb content the reflectivity minimum in the near infrared spectral range shifts towards lower wavenumber indicating the effect of decreasing carrier concentration. Pyrochlore type phase (KNbWO₆) is obtained as a second phase when nominal composition y > 0.07.     

A variational principle for nonlinear water waves

Summary This paper is concerned with a variational formulation of non-axisymmetric water waves and of two-dimensional surface waves in a running stream of finite depth. The full set of equations of motions for the non-axisymmetric water wave problem in cylindrical polar coordinates and for the two-dimensional surface waves in the running stream in Cartesian coordinates is obtained from a Lagrangian function which is equal to the pressure.With 1 Figure     

Effect of lidocaine and quinidine on focal ventricular arrhythmias induced by subepicardial epinephrine in cats

Subepicardial infusion of epinephrine (EP) in the dose of 3 x 10(-3) M in 2.5 x 10(-3)M CaCl2-0.9% NaCl (calcium-saline vehicle) at the rate of 10 microliters/min in the right ventricular myocardium of mongrel cats weighing between 2.7 and 3.3 kg produced uniform reversible and reproducible focal ventricular arrhythmias of varying intensity and duration. Infusion of two antiarrhythmic agents, lidocaine (LD) and quinidine (QD) in the same site of arrhythmogenesis in equimolar concentration of 3 x 10(-3) M along with EP in the same vehicle reduced incidence, duration, peak and mean frequencies of arrhythmias while the latent period of onset of arrhythmias increased significantly. In present study, quinidine, in equimolar concentration of 3 x 10(-3) M was found to be more effective than lidocaine in antagonizing EP-induced ventricular arrhythmias.     

Evaluation of the fertilizer value of some indigenous rock phosphates and basic slag of India

Summary Field and pot culture experiments were conducted in terai acid soil (Haplaquoll) to evaluate the fertilizer value of one basic slag and two rock phosphates, such as Purulia rock phosphate (Igneous) and Mussoorie rock phosphate (sedimentary). In the field experiments two crop sequences were followed: (i) Rice — wheat — greengram (ii) Greengram — rice — wheat. In terms of crop yield and P uptake Purulia rock phosphate did not show any significant effect, except in case of greengram grown as the third crop after its application. Mussoorie rock phosphate increased the yield and P uptake through its direct and residual effect in all the crops, except in rice. Irrespective of crop species and crop sequences basic slag showed considerable direct and residual effect in increasing the crop yield and P uptake. Its effect was at par with that of superphosphate. By total yield increase of three consecutive crops due to added P the efficiencies of the fertilizers were graded as basic slag > superphosphate = Mussoorie rock phosphate > Purulia rock phosphate for rice — wheat — greengram rotation and superphosphate > basic slag > Mussoorie rock phosphate > Purulia rock phosphate for greengram — rice —wheat rotation. Composting improved the efficiency of all the insoluble phosphatic fertilizers.     

Multi-objective shape optimization using ant colony coupled computational fluid dynamics solver

An adaptation of a parametric ant colony optimization (ACO) to multi-objective optimization (MOO) is presented in this paper. In this algorithm (here onwards called MACO) the concept of MOO is achieved using the reference point (or goal vector) optimization strategy by applying scalarization. This method translates the multi-objective optimization problem to a single objective optimization problem. The ranking is done using ?-dominance with modified L_p metric strategy. The minimization of the maximum distance from the goal vector drives the solution close to the goal vector. A few validation test cases with multi-objectives have been demonstrated. MACO was found to out perform R-NSGA-II for the test cases considered. This algorithm was then integrated with a meshless computational fluid dynamics (CFD) solver to perform aerodynamic shape optimization of an airfoil. The algorithm was successful in reaching the optimum solutions near to the goal vector on one hand. On the other hand the algorithm converged to an optimum outside the boundary specified by the user for the control variables. These make MACO a good contender for multi-objective shape optimization problems.     

Chemical surface treatment of ultrahigh molecular weight polyethylene for improved adhesion to methacrylate resins

Ultrahigh molecular weight polyethylene (UHMWPE) has high yield strength and modulus, but is nonpolar and chemically inert. For it to be used as an effective reinforcing agent for composites, methods to make the UHMWPE wettable or capable of reaction with the matrix are critical. In the current work, Spectra 900? (UHMWPE) fibers were surface modified by swelling in p‐xylene with: (1) methylmethacrylate (MMA) monomer; (2) PMMA; (3) camphorquinone (CQ); (4) 3‐methacryloxypropyltrichlorosilane (Cl‐MPS); (5) trimethoxysilyl modified polyethylene, N‐(triethoxysilylpropyl)‐dansylamide (fluorescent silane), or octadecyltrimethoxy silane (OMS), followed by hydrolysis and reaction with Cl‐MPS; and (6) by coating with SiO₂ films followed by reaction with MPS. These modifiers were used to improve wettability and provide sites for chemical interactions with the resin matrix. Beads of resin [60/40 BisGMA‐TEGMA (bis‐phenol A bis‐(2‐hydroxypropyl) methacrylate and tri(ethylene glycol) dimethacrylate)] were light‐cured around the treated fibers and the improvement in adhesion was tested by microbond shear strength (τ) tests. The improvements were comparable to those reported by acid etching and plasma treatments. The OMS, fluorescent silane, and SiO₂/Cl‐MPS treatments yielded the best results, that is fourfold increases in τ compared with untreated fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1564–1572, 2005     

Genome-Wide Identification and Characterization of the Brassinazole-resistant (BZR) Gene Family and Its Expression in the Various Developmental Stage and Stress Conditions in Wheat (Triticum aestivum L.)

Brassinosteroids (BRs) play crucial roles in various biological processes, including plant developmental processes and response to diverse biotic and abiotic stresses. However, no information is currently available about this gene family in wheat (Triticum aestivum L.). In the present investigation, we identified the BZR gene family in wheat to understand the evolution and their role in diverse developmental processes and under different stress conditions. In this study, we performed the genome-wide analysis of the BZR gene family in the bread wheat and identified 20 TaBZR genes through a homology search and further characterized them to understand their structure, function, and distribution across various tissues. Phylogenetic analyses lead to the classification of TaBZR genes into five different groups or subfamilies, providing evidence of evolutionary relationship with Arabidopsis thaliana, Zea mays, Glycine max, and Oryza sativa. A gene exon/intron structure analysis showed a distinct evolutionary path and predicted the possible gene duplication events. Further, the physical and biochemical properties, conserved motifs, chromosomal, subcellular localization, and cis-acting regulatory elements were also examined using various computational approaches. In addition, an analysis of public RNA-seq data also shows that TaBZR genes may be involved in diverse developmental processes and stress tolerance mechanisms. Moreover, qRT-PCR results also showed similar expression with slight variation. Collectively, these results suggest that TaBZR genes might play an important role in plant developmental processes and various stress conditions. Therefore, this work provides valuable information for further elucidate the precise role of BZR family members in wheat.     

Profiling and Functional Analysis of microRNA Deregulation in Cancer-Associated Fibroblasts in Oral Squamous Cell Carcinoma Depicts an Anti-Invasive Role of microRNA-204 via Regulation of Their Motility

Background: Knowledge on the role of miR changes in tumor stroma for cancer progression is limited. This study aimed to investigate the role of miR dysregulation in cancer-associated fibroblasts (CAFs) in oral squamous cell carcinoma (OSCC). Methodology: CAF and normal oral fibroblasts (NOFs) were isolated from biopsies of OSCC patients and healthy individuals after informed consent and grown in 3D collagen gels. Total RNA was extracted. Global miR expression was profiled using Illumina version 2 panels. The functional impact of altered miR-204 expression in fibroblasts on their phenotype and molecular profile was investigated using mimics and inhibitors of miR-204. Further, the impact of miR-204 expression in fibroblasts on invasion of adjacent OSCC cells was assessed in 3D-organotypic co-cultures. Results: Unsupervised hierarchical clustering for global miR expression resulted in separate clusters for CAF and NOF. SAM analysis identified differential expression of twelve miRs between CAF and NOF. Modulation of miR-204 expression did not affect fibroblast cell proliferation, but resulted in changes in the motility phenotype, expression of various motility-related molecules, and invasion of the adjacent OSCC cells. 3′ UTR miR target reporter assay showed ITGA11 to be a direct target of miR-204. Conclusions: This study identifies differentially expressed miRs in stromal fibroblasts of OSCC lesions compared with normal oral mucosa and it reveals that one of the significantly downregulated miRs in CAF, miR-204, has a tumor-suppressive function through inhibition of fibroblast migration by modulating the expression of several different molecules in addition to directly targeting ITGA11.     

Structural changes of horseradish peroxidase in presence of low concentrations of urea

The presence of very low concentrations of the widely used denaturant urea induces structural changes in the monomeric heme-containing enzyme, horseradish peroxidase (HRP). Structural alterations in the protein were reflected in quenching studies of tryptophan fluorescence using the widely used quencher acrylamide. Stern-Volmer quenching constants measured in presence of urea, even in concentrations below 100 mm, were higher than those measured in absence of the denaturant. The fluorescence emission maximum of 1, 8-ANS, used as a probe for monitoring conformational changes in the enzyme, was blue-shifted from 530 nm in aqueous buffer to 518 nm when incorporated in native HRP. This blue shift increased further by 3 nm in presence of HRP preincubated with 100 mm urea, whereupon it steadily decreased with increasing urea concentration to become zero at 8 m urea. The mean fluorescence lifetime of 1,8-ANS incorporated in HRP was much higher than that of ANS in aqueous buffer, and showed continuous variation with the concentration of urea in which the enzyme was incubated. Systematic changes in the microenvironment of the heme moiety in HRP were also reflected in the visible CD spectra of the enzyme incubated with low concentrations of urea. These results are consistent with those of our earlier studies performed with the denaturant guanidinium chloride and indicate structural relaxation of HRP, with retention of enzymatic activity and native-like secondary structure, in presence of millimolar concentrations of urea.