Hydraulic Jump in One-dimensional Flow

In the presence of viscosity the hydraulic jump in one dimension is seen to be a first-order transition. A scaling relation for the position of the jump has been determined by applying an averaging technique on the stationary hydrodynamic equations. This gives a linear height profile before the jump, as well as a clear dependence of the magnitude of the jump on the outer boundary condition. The importance of viscosity in the jump formation has been convincingly established, and its physical basis has been understood by a time-dependent analysis of the flow equations. In doing so, a very close correspondence has been revealed between a perturbation equation for the flow rate and the metric of an acoustic white hole. We finally provide experimental support for our heuristically developed theory.Comment: 17 Pages, 8 Figures, 1 Table. To appear in European Physical Journal

Aharonov-Bohm effect in the presence of evanescent modes

It is known that differential magnetoconductance of a normal metal loop connected to reservoirs by ideal wires is always negative when an electron travels as an evanescent modes in the loop. This is in contrast to the fact that the magnetoconductance for propagating modes is very sensitive to small changes in geometric details and the Fermi energy and moreover it can be positive as well as negative. Here we explore the role of impurities in the leads in determining the magnetoconductance of the loop. We find that the change in magnetoconductance is negative and can be made large provided the impurities do not create resonant states in the systems. This theoretical finding may play an useful role in quantum switch operations.Comment: 9 figures available on reques

Study of Boron Precipitates Formed during Front Side Emitter Formation with Boron Spin on Dopant (BSOD) Diffusion in n- type c- Si Solar Cells

AbstractBoron precipitates formed during boron source diffusion is an unwanted phenomenon during front side emitter formation in n- type crystalline silicon solar cells. Boron spin on dopant (BSOD) is one of the mostly preferred alternative dopant sources to conventional liquid BBr3, used for p- type emitter formation, but has problems of forming boron precipitates during its diffusion. In this work, we have studied boron precipitates formed by BSOD diffusion and characterized borosilicate glass layer (BSG) and boron rich layer (BRL) at different process parameters. We have tried different process controlled steps to get very less amount of boron precipitates on the surface during diffusion of BSOD source and were successful in reducing boron precipitates from 56% atomic and 36% weight percentages to 0% values for optimized sheet resistance value of 50±5Ω/ sq for the front side emitter

On the structure and spectrum of classical two-dimensional clusters with a logarithmic interaction potential

We present a numerical study of the effect of the repulsive logarithmic inter-particle interaction on the ground state configuration and the frequency spectrum of a confined classical two-dimensional cluster containing a finite number of particles. In the case of a hard wall confinement all particles form one ring situated at the boundary of the potential. For a general r^n confinement potential, also inner rings can form and we find that all frequencies lie below the frequency of a particular mode, namely the breathing-like mode. An interesting situation arises for the parabolic confined system(i.e. n=2). In this case the frequency of the breathing mode is independent of the number of particles leading to an upper bound for all frequencies. All results can be understood from Earnshaw's theorem in two dimensions. In order to check the sensitivity of these results, the spectrum of vortices in a type II superconductor which, in the limit of large penetration depths, interact through a logarithmic potential, is investigated.Comment: 11 pages, 6 figure

Effect of chemical reaction and viscous dissipation on MHD nanofluid flow over a horizontal cylinder : analytical solution

An analytical study of the MHD boundary layer flow of electrically conducting nanofluid over a horizontal cylinder with the effects of chemical reaction and viscous dissipation is presented. Similarity transformations have been applied to transform the cylindrical form of the governing equations into the system of coupled ordinary differential equations and then homotopy analysis method has been implemented to solve the system. HAM does not contain any small or large parameter like perturbation technique and also provides an easiest approach to ensure the convergence of the series of solution. The effects of chemical reaction parameter, magnetic parameter and other important governing parameters with no flux nanoparticles concentration is carried out to describe important physical quantities

Resistively-detected NMR lineshapes in a quasi-one dimensional electron system

We observe variation in the resistively-detected nuclear magnetic resonance (RDNMR) lineshapes in quantum Hall breakdown. The breakdown is locally occurred in a gate-defined quantum point contact (QPC) region. Of particular interest is the observation of a dispersive lineshape occured when the bulk 2D electron gas (2DEG) is set to $\nu_{\rm{b}} = 2$ and the QPC filling factor to the vicinity of $\nu_{\rm{QPC}} = 1$, strikingly resemble the dispersive lineshape observed on a 2D quantum Hall state. This previously unobserved lineshape in a QPC points to simultaneous occurrence of two hyperfine-mediated spin flip-flop processes within the QPC. Those events give rise to two different sets of nuclei polarized in the opposite direction and positioned at a separate region with different degree of electronic polarizations.Comment: Accepted as a rapid communication in PR

Functional and catalytic active sites prediction and docking analysis of azoreductase enzyme in Pseudomonas putida with a variety of commercially available azodyes

The initial critical step of reduction of azo bond during the metabolism of azo dyes is catalysed by a group of NADH and FAD dependant enzyme called azoreductases. Although several azoreductases have been identified from microorganisms and partially characterized, very little is known about the structural basis of the substrate specificity and the nature of catalysis. Azoreductase enzyme of Pseudomonas putida has a wider broad spectrum of substrate specificity and capable of degrading a wide variety of azo dyes. In the present study, the crystal structure of the enzyme from PDB and 10 azo dyes from NCBI PubChem compound were retrieved and their interactions were studied. These azo dyes were then docked with the FMN-dependent NADH-azoreductase enzyme to analyze the binding affinity of the azo dyes with the enzyme and predict the catalytic sites. Consequently, the catalytic residues of FMN-dependent and NADH dependent enzyme were then analysed in terms of properties including function, hydrogen bonding and flexibility. The results suggest that Ala-114, Phe-172 and Glu-174 play a predominant role as catalytic site residues in the enzyme. Furthermore, the approach emphasis on predicting the active sites of this enzyme where substrates can bind in order to give a better understanding of the biodegradation of some of the commercially important azodyes mediated by azoreductase. These results will pave way for further increase in azoreductase activity and for better understanding of the dye degradation pathway.Keywords: Azoreductase, NADH, FMN, chemical properties, docking, active sites