The critical values of coupling strength of the non-self-dual Ising lattices under decimation transformation

In this work, the values of critical coupling strengths of the Ising lattices which are changing their lattice structure (or non-self-dual) under decimation transformations, such as the honeycomb, the triangular and the body centered cubic Ising lattices, are obtained by a modified real space renormalization group approach (RSRG). This modification is necessary to obtain a proper relation between the coupling strengths of the original and the decimated lattices. Indeed, we have achieved to obtain a proper renormalized coupling strength relation for honeycomb and triangular lattices readily, since the decimation transformation of the honeycomb lattice produces the triangular lattice or vice versa. Here, the problem of having physically untractable interactions between degrees of freedom in the renormalized Hamiltonian, which leads eventually to inevitable approximations in the treatment, except for the 1D Ising chain, has been solved with a proper approximation. Especially for the 3D Ising lattices, the physically untractable interactions appearing in the renormalized Hamiltonian make the mathematical treatment too cumbersome. As a result, there is not enough research dealing with the 3D Ising lattices using RG theory. Our approximation is based on using the simple relation [Formula: see text], which is, of course, a very relevant first-order approximation, if [Formula: see text]. With the help of this approximation, decimation transformation process produces only pairwise interactions in the renormalized Hamiltonian instead of having four spins, six spins, or even eight spin interactions which appear naturally if all the terms are kept in the renormalized Hamiltonians of the Ising lattices in 2D and higher dimensions. Without this approximation, one cannot apply analytic RG treatment feasibly to even simple cubic lattice, let alone applying it to the body centered cubic lattice. Using this modified RG approach, the values of critical coupling strengths of the honeycomb, the triangular and the body centered cubic Ising lattices are obtained analytically as [Formula: see text], [Formula: see text] and [Formula: see text] respectively. Apparently, these estimations are really close to the results obtained from cumbersome exact treatments which are [Formula: see text], [Formula: see text] and [Formula: see text] for the honeycomb, the triangular and the body centered cubic lattices.

Green Synthesis of Ceria Nanoparticles Using Azadirachta Indica Plant Extract: Characterization, Gas Sensing and Antibacterial Studies

In the present investigation we have fabricated the cerium dioxide (CeO2) nanoparticles by green route. While preparing the cerium dioxide nanoparticles by co-precipitation method, Neem leaf extract mixed into the precursor of cerium. The synthesized nanoparticles of CeO2 were used for the preparation of thick film sensor by using screen printing strategy. The fabricated CeO2 sensor was characterized by XRD, SEM, EDS and TEM techniques. The structural characteristics investigated by x-ray diffraction technique (XRD). XRD confirms the formation of cubic lattice of CeO2 material. The surface, texture, porosity characteristics were investigated from SEM analysis, while chemical composition of the material was analysed by EDS technique. The transmission electron microscopy (TEM) confirms the formation cubic lattice of the cerium dioxide material. The thickness of the films was calculated from mass difference method, the prepared film sensors belong to thick region. The fabricated material CeO2 sensor was applied as gas sensor to sense the gases such as LPG, petrol vapors (PV), toluene vapors (TV) and CO2. The CeO2 sensor showed excellent gas response for LPG and PV, nearly 93.20 % and 78.23 % gas response. The rapid response and recovery of the prepared sensors was observed at the tested gases. CeO2 material also employed for antibacterial study at several pathogenic organism such as pseudomonas, staphylococcus aureus and salmonella typhae. From antibacterial study it was observed that the material is capable of inhibiting the growth of these pathogenic microbes.

Synthesis and Characterization of Barium-Iron Oxide Based Neodymium, Gadolinium and Praseodymium Doped Ceramic Materials

Neodymium, gadolinium, and praseodymium doped barium-iron oxide ceramic materials were synthesized by polymeric precursor method. No carbon contents or the moisture was observed in infrared spectra of the ceramics. Neodymium and gadolinium doped ceramics were crystallized in cubic lattice form, while praseodymium doped ceramic was formed in hexagonal lattice. Same results were observed from SEM images, Neodymium and gadolinium doped ceramics had similar morphological structures, but praseodymium doped ceramics had slightly different morphology. Neodymium and gadolinium doped ceramics consisted of grain-like structure, while praseodymium doped ceramic material consisted of both grain-like and pillar-like crystal structures.

Polymerization and Structure of Opposing Polymer Brushes Studied by Computer Simulations

A model of the polymerization process during the formation of a pair of polymer brushes was designed and investigated. The obtained system consisted of two impenetrable parallel surfaces with the same number of chains grafted on both surfaces. Coarse-grained chains embedded in nodes of a face-centered cubic lattice with excluded volume interactions were obtained by a ‘grafted from’ procedure. The structure of synthesized macromolecular systems was also studied. Monte Carlo simulations using the dynamic lattice liquid model were employed using dedicated parallel machine ARUZ in a large size and time scale. The parameters of the polymerization process were found to be crucial for the proper structure of the brush. It was found that for high grafting densities, chains were increasingly compressed, and there is surprisingly little interpenetration of chains from opposite surfaces. It was predicted and confirmed that in a polydisperse sample, the longer chains have unique configurations consisting of a stretched stem and a coiled crown.

Linking and link complexity of geometrically constrained pairs of rings

We investigate and compare the effects of two different constraints on the geometrical properties and linking of pairs of polygons on the simple cubic lattice, using Monte Carlo methods. One constraint is to insist that the centres of mass of the two polygons are less than distance $d$ apart, and the other is to insist that the radius of gyration of the \emph{pair} of polygons is less than $R$. The second constraint results in links that are quite spherically symmetric, especially at small values of $R$, while the first constraint gives much less spherically symmetric pairs, prolate at large $d$ and becoming more oblate at smaller $d$. These effects have an influence on the observed values of the linking probability and link spectrum.

Electronic and Vibrational Properties of Fe2NiAl and Co2NiAl Full Heusler Alloys: A First-Principles Comparison

<p>In this work, we report on a systematic first-principles study of the structural, electronic, vibrational and thermodynamic properties of the cubic Fe₂NiAl and tetragonally distorted Co₂NiAl full Heusler compounds. We discuss systematically the competition between the inverse Heusler structure and a T<i>^p</i>-type layered atomic ordering formed by the alternating planes of (Fe,Co) and Ni atoms in terms of the electronic and vibrational density of states.</p> <p>Such an arrangement is predicted to be the ground state of Fe₂NiAl. For Co₂NiAl, layered ordering has slightly higher energy in comparison with the inverse one, however, we show that it might be stabilized at rather low temperatures.</p> <p> </p> <p>Due to the broken symmetry, layered T<i>^p</i>-Fe₂NiAl possesses a large MAE of the same order as tetrataenite FeNi - even in a phase with cubic lattice parameters, which makes a T<i>^p</i>-type layered order an interesting feature for rare-earth free permanent magnets in Heusler-type compounds.</p>