Aldehyde Oxidase Activity and Stability in Water-Miscible Organic Solvents

In this study, the catalytic activity of aldehyde oxidase was investigated in various water-miscible organic solvents for the first time. The enzyme was partially purified from rabbit liver, and its activity was determined in the absence/presence of nine hydro-organic mixtures. The effects of pH and temperature on the enzyme activity were also investigated. The activity was reduced in the presence of all nine organic solvents. However, in some cases, the residual activity remained almost unchanged throughout the incubation of enzyme at 35 °C for 24 h. Considering potential advantages of doing reactions in the presence of organic solvents, these results could be of value. The enzyme showed different behavior in the reaction solutions making it difficult to formulate results in a single comprehensive model. The results indicated that binding and cleavage of the substrate are influenced in the presence of organic solvents.     

Electronic and magnetic properties of iron adsorption on graphene with double hexagonal geometry

Motivated by recent experimental and theoretical works dealing with the silicene and the graphene materials and inspired from the root systems of Lie algebras, we study the electronic and the magnetic properties of the iron adatom adsorption on the graphene. The calculations have been performed using the density functional theory method. More precisely, the system we consider here consists of a static single layer of the graphene interacting with the iron atoms which are placed at hollow (H) sites and localized at a distance Δ along the normal direction. This system, involving the G₂ hexagons appearing in the classification of rank two Lie symmetries, exhibits, up some details, a nice double hexagonal symmetry required by coverage of 0.666 monolayer placed at H sites. The resulting materials behave like ferromagnetic ones having a strong spin polarization, instead of gapless‐semiconductor with the nonmagnetic features appearing in the pure graphene. The responsible mechanism for such behaviors is the interaction between the iron atoms. It has been realized that there are two interaction types. The first one is associated with the direct interaction between the iron atoms, whereas the second one corresponds to the indirect interaction via the carbon atoms. Using the molecular field approximation, the Curie temperature has been estimated around 367 K. © 2013 Wiley Periodicals, Inc.     

Chorded complexes and a necessary condition for a monomial ideal to have a linear resolution

In this paper we extend one direction of Fröberg?s theorem on a combinatorial classification of quadratic monomial ideals with linear resolutions. We do this by generalizing the notion of a chordal graph to higher dimensions with the introduction of d-chorded and orientably-d-cycle-complete simplicial complexes. We show that a certain class of simplicial complexes, the d-dimensional trees, correspond to ideals having linear resolutions over fields of characteristic 2 and we also give a necessary combinatorial condition for a monomial ideal to be componentwise linear over all fields.     

Precession of angular momentum vector in a slowly rotating Kerr metric

Specializing Penrose and Floyd's resultF _ab;c =F _[ab;c] to the Kerr metric, we explicitly construct the skew symmetric tensorF _ab and Carter's quadratic integral of geodesic motion.F _ab is then shown to be closely related to the orbital angular momentum encountered in Newtonian mechanics. Furthermore, F_ab can be decomposed additively intoL _ab andM _ab , whereL _ab has the character of angular momentum, andM _ab exists only for a nonzero rotation parameter,a, of the Kerr metric. It turns out that the equation of precession = _a ^b L _b has a nontrivial solution only for the case of a slowly rotating Kerr metric valid to first order in rotation parameter. In this case, Carter's integral can be interpreted as the squared length of the precessing angular momentum vectorL _a =L _a ^b P _b . The equation of precession is solved, and a vector ^a describing angular velocity of precession is derived.     

Elucidating DFT study on structural,electronic, thermal and elastic properties of SrTcO3 by using GGA and mBJ approach

Generalized gradient approximation and Modified Becke and Johnson (mBJ) potential scheme, within density functional theory, has been implemented to evaluate the structural, electronic and thermo-elastic attributes of SrTcO₃. The structural stability of the very compound has been probed from tolerance factor, elastic stability criterion and ground state optimizations. In the study of electronic properties, formation of band-gap has been resolved by using density of states and from electron spin density contour plots. It is for the first time that mechanical and thermo-dynamical properties have been studied in terms of elastic constants, melting temperature, enthalpy of formation and Debye temperature. Our results have shown that SrTcO₃ exhibit a stable ductile nature that makes it a convincing candidate for high temperature electronic applications.     

Experimental investigation of TiO2–water nanofluid flow and heat transfer inside wavy mini-channel heat sinks

Journal of Thermal Analysis and Calorimetry - The present study comprises experimental investigation on heat transfer and hydrodynamic characteristics of TiO2 nanofluid as coolant in wavy channel...     

A Complete Foliation of Schwarzschild Spacetime by Free Falling Hypersurfaces

Free falling hypersurfaces in the Schwarzschild geometry have been studied to provide a complete foliation of spacetime. The hypersurfaces do not cross into the maximally extended spacetime and are well behaved everywhere except at the singularity r =0 the mean extrinsic curvature becomes infinity.     

The facet ideal of a simplicial complex

 To a simplicial complex, we associate a square-free monomial ideal in the polynomial ring generated by its vertex set over a field. We study algebraic properties of this ideal via combinatorial properties of the simplicial complex. By generalizing the notion of a tree from graphs to simplicial complexes, we show that ideals associated to trees satisfy sliding depth condition, and therefore have normal and Cohen-Macaulay Rees rings. We also discuss connections with the theory of Stanley-Reisner rings. Received: 7 January 2002 / Revised version: 6 May 2002