Dimensional Order Research Articles

VERSATILE ROSELLE GRAFT-COPOLYMERS: XRD STUDIES AND THEIR MECHANICAL EVALUATION AFTER USE AS REINFORCEMENT IN COMPOSITES

Roselle is rich in cellulose content and exists as waste bio-mass in abundance thorough-out the world. It has low weight and high tensile strength that promotes its use as backbone for graft copolymerization. Various reaction parameters for the graft co-polymerization of effective acrylate monomer onto stem fiber were optimized and used in binary mixture with six vinyl monomers to screen the change in properties of the fiber. These graft copolymers were characterized by advanced analytical techniques and evaluated for mechanical strength after being incorporated in polymer matrix based composite as reinforcement. . Cellulosic fiber possesses both crystalline and amorphous regions. The x-ray pattern of the crystalline polymer shows sharp peaks associated with the region of three dimensional order and the diffused features are characteristics of the molecularly disordered substances coexisting within itself. Lower crystallinity means higher amorphous content that may be more accessible to chemicals and water. Crystallinity is correlated to the strength of the fiber. On grafting crystal lattice of the polymer is disrupted but the strength of the material may add to reinforce the structure. However, if crystallinity is not affected on grafting then a continuous increase in strength can be obtained 11-14 . Hibiscus sabdariffa (Hs, Roselle) is found in abundance in nature through-out and has attained prominence as a jute substitute and attempts are being made to extend its cultivation in areas which are not favorable for jute cultivation. Good mechanical properties were found when injection-molded isotactic polypropylene/Roselle fiber composites were studied 15-16 , but still remain unexplored for its viability as substrate to grafting by vinyl monomers. The versatility of this chemical technique inspired the thoughts to implement it on the virgin Roselle fiber by using effective n-butyl acrylate as a principal monomer and its binary mixtures with acrylonitrile, 4-vinyl pyridine, methyl acrylate, acrylic acid, acrylamide and vinyl acetate to screen the change in the percentage grafting, morphology, crystallinity by FTIR, SEM and XRD studies and use the raw and the grafted fiber as reinforcement in Phenol- formaldehyde polymer matrix to form fiber -reinforced- composite for its comparative mechanical accreditation. The morphological transformation after use of binary vinyl monomeric mixtures for grafting by XRD and use of Sereni graft copolymers as reinforcement in polymer matrix based composites still remains unexplored.

Layered inorganic–organic frameworks based on the 2,2-dimethylsuccinate ligand: structural diversity and its effect on nanosheet exfoliation and magnetic properties

The structures of four new 2,2-dimethylsuccinate frameworks suitable for exfoliation into nanosheets using ultrasonication are reported. These hybrid compounds contain either monovalent (Li(+)) or divalent (Co(2+) and Zn(2+)) cations, and they all feature hydrophobically capped covalently bonded layers that only interact with each other via weak van der Waals forces. Critically this shows that the use of this dicarboxylate ligand generally yields two dimensional compounds suitable for simple and affordable nanosheet exfoliation. This extends the range of frameworks that can be exfoliated and highlights the 2,2-dimethylsuccinate ligand as an excellent versatile platform for the production of nanosheets. The topologies of the layers in each framework were found to vary significantly and this appears to have a significant effect on the relative size of the nanosheets produced; increased space between methyl groups and more extensive inorganic connectivity appears to favour the formation of thin nanosheets with larger lateral dimensions. Additionally the magnetic properties of two of these frameworks were examined, and it was found that both exhibit strong low dimensional antiferromagnetic coupling despite their well-separated layers preventing three dimensional magnetic order.

Spin correlations in the extended kagome system YBaCo3FeO7

The transition metal based oxide YBaCo3FeO7 is structurally related to the mineral Swedenborgite SbNaBe4O7, a polar non-centrosymmetric crystal system. The magnetic Co3Fe sublattice consists of a tetrahedral network containing kagome-like layers with trigonal interlayer sites. This geometry causes frustration effects for magnetic ordering, which were investigated by magnetization measurements, M\"ossbauer spectroscopy, polarized neutron diffraction, and neutron spectroscopy. Magnetization measurement and neutron diffraction do not show long range ordering even at low temperature (1 K) although a strong antiferromagnetic coupling (~2000 K) is deduced from the magnetic susceptibility. Below 590 K, we observe two features, a spontaneous weak anisotropic magnetization hysteresis along the polar crystallographic axis and a hyperfine field on the Fe kagome sites, whereas the Fe spins on the interlayer sites remain idle. Below ~50 K, the onset of a hyperfine field shows the development of moments static on the M\"ossbauer time scale also for the Fe interlayer sites. Simultaneously, an increase of spin correlations is found by polarized neutron diffraction. The relaxation part of the dynamic response has been further investigated by high-resolution neutron spectroscopy, which reveals that the spin correlations start to freeze in below ~50 K. Monte Carlo simulations show that the neutron scattering results at lower temperatures are compatible with a recent proposal that the particular geometric frustration in the Swedenborgite structure promotes quasi one dimensional partial order.

IR transition moment orientational analysis on semi-crystalline polyethylene films

The recently developed approach of Transition Moment Orientation Analysis is employed to determine the three dimensional orientation and order of the different molecular moieties in semi-crystalline polyolefins. Based on IR transmission spectra for varying polarisation and inclination the quadratically averaged orientation distribution of the different IR transition moments is deduced. By that, the full order parameter tensor and its orientation with respect to the sample coordinate system is obtained.

High accuracy cubic spline finite difference approximation for the solution of one-space dimensional non-linear wave equations

In this paper, we propose a new three-level implicit nine point compact cubic spline finite difference formulation of order two in time and four in space directions, based on cubic spline approximation in x-direction and finite difference approximation in t-direction for the numerical solution of one-space dimensional second order non-linear hyperbolic partial differential equations. We describe the mathematical formulation procedure in details and also discuss how our formulation is able to handle wave equation in polar coordinates. The proposed method when applied to a linear hyperbolic equation is also shown to be unconditionally stable. Numerical results are provided to justify the usefulness of the proposed method.

Variable selection and estimation in high-dimensional varying-coefficient models

Nonparametric varying coefficient models are useful for studying the time-dependent effects of variables. Many procedures have been developed for estimation and variable selection in such models. However, existing work has focused on the case when the number of variables is fixed or smaller than the sample size. In this paper, we consider the problem of variable selection and estimation in varying coefficient models in sparse, high-dimensional settings when the number of variables can be larger than the sample size. We apply the group Lasso and basis function expansion to simultaneously select the important variables and estimate the nonzero varying coefficient functions. Under appropriate conditions, we show that the group Lasso selects a model of the right order of dimensionality, selects all variables with the norms of the corresponding coefficient functions greater than certain threshold level, and is estimation consistent. However, the group Lasso is in general not selection consistent and tends to select variables that are not important in the model. In order to improve the selection results, we apply the adaptive group Lasso. We show that, under suitable conditions, the adaptive group Lasso has the oracle selection property in the sense that it correctly selects important variables with probability converging to one. In contrast, the group Lasso does not possess such oracle property. Both approaches are evaluated using simulation and demonstrated on a data example.

EPR in functional structures based on doped (nano, meso)-porous silica and titanium dioxide

EPR investigations are performed on mesoporous silica (SBA15) functionalized by Nickel-cyclam complexes (1,4,8,11-tetraazacyclotetradecane groups chelating nickel ions) and on mesoporous titanium dioxide with nitrogen doping. For functionalized silica, the magnetic behaviour of organometallic groups, their mutual interactions and dispersion in the host matrices are compared with respect to the doping rates and the synthesis procedures. The relaxation processes were analyzed from the thermal evolution of the paramagnetic spin susceptibilities and EPR line-widths. Particularly, some samples show the formation of clusters where phonon assisted one dimensional (1D) ferromagnetic ordering occurs below 45 K. For the mesoporous TiO2, systematic EPR investigations were performed on two main classes of materials with regard to the porosity degrees. The EPR experiments point out the efficiency of EPR method to probe the degree of functionalization of mesoporous silica or the nitrogen doping achievement in TiO2, and in general to give a valuable feedback to improve the synthesis routes of smart materials.

Semi-foldon fission and fusion in the (2+1 )-dimensional higher order Broer–Kaup system

We obtain the general variable separation solution of the (2+1)-dimensional higher order Broer–Kaup system via the separation variable method, and study semi-foldon fission and fusion based on this variable separation solution.

Composition and structure of nanocrystalline Fe and Mn oxide cave deposits: Implications for trace element mobility in karst systems

Fe and Mn oxides are ubiquitous, highly reactive minerals in the environment which often control the distribution and speciation of trace elements in soils and aquatic systems. Pautler Cave in Southwest Illinois contains Fe and Mn oxide deposits with properties that differ spatially and temporally. Two depositional environments exist in the cave: Fe and Mn precipitation where anoxic groundwater enters the oxic cave passage (seep deposition) and direct deposition from the cave stream. Seep waters have higher concentrations of Ca 2+, Fe 2+, and Mn 2+, lower pH, and lower O 2(aq) concentrations relative to stream waters. In addition, seep waters have nearly constant δ 18O values that are similar to the yearly average of local precipitation, whereas cave stream waters have more erratic δ 18O values and appear to be influenced by seasonal variations of δ 18O in rainfall. These differences suggest that the seep water source has a longer residence time in the subsurface than the cave stream water. Fe oxides are solely found as seep deposits whereas Mn oxides are deposited both by groundwater seepage and cave streams. Freshly precipitated Fe oxides are composed of ferrihydrite and filamentous material consistent with biomineralization structures of the microbial genera Gallionella and Leptothrix. Mn oxide minerals consist of 7 and 10 Å phyllomanganates having a range of three dimensional order. Mn oxide samples show a greater heavy metal and trace element content compared to Fe oxides, and Mn oxides deposited by cave streams have higher concentrations of metals than Mn oxide seep deposits. In addition, phyllomanganate particle morphologies and crystallinity display a compositional dependence, with platelet size and phyllomanganate sheet stacking-order decreasing with increasing Ba and trace element content and decreasing Ca content; these properties also appear to correlate with dissolved Mn(II) in the source water. These observations suggest that Fe and Mn oxide minerals in oxic cave systems affect trace element concentrations in carbonate-fed springs, and illustrate a previously unrecognized limitation on the transport of inorganic nutrients and contaminants in karst aquifers.

PROPAGATION AND RUNUP OF TSUNAMI WAVES WITH BOUSSINESQ MODEL

With certain profiles of bottom movements, orders of wave height of submarine earthquake-induced tsunami both in deep ocean and nearshore area have been studied using the Boussinesq equations. An earthquake of large magnitude generates a typical N-wave which can propagate long distance in open ocean without deformation. Since the magnitude and length of tsunami waves related to vertical and horizontal scale of geological movements, solitary wave and N-wave are extended to waves not tied to solitary property which represent tsunami waves better. In a horizontal one dimensional numerical wave flume, runup of solitary wave, N-wave, single crest and N-wave composed by a single crest and a single trough on a slope beach have been simulated. The results fit analytical solutions of nonlinear shallow water equations well. The Indian Ocean tsunami has been simulated with the horizontal two dimensional high order Boussinesq model. Comparison between numerical results and measured data from field survey validates the numerical model.

The Traveling Wave Solutions for Some Nonlinear PDEs in Mathematical Physics

In the present article, we construct the exact traveling wave solutions of some nonlinear PDEs in the mathematical physics via (1 + 1) dimensional Kaup Kupershmit equation, the (1 + 1) dimensional seventh order KdV equation and (1 + 1) dimensional Kersten-Krasil Shchik equations by using the modified truncated expansion method. New exact solutions of these equations are found.

Theoretical and Experimental Study of a Forward Swept Wing

The aerodynamic characteristics of forward swept wing were studied theoretically and experimentally .In the present work, theoretically a computer program was constructed to predict the pressure distribution about surface of the wing using three dimensional Low Order Subsonic Panel method. The aerodynamic coefficients of the wing were calculated from the pressure distribution which gained from tangential velocities Experimentally ,test were carried out by designing and manufacturing a wing model with special arrangement for pressure tapping, suitable for low wind tunnel testing. The entire wing was rotated rotate about an axis in the plane of symmetry and normal to the chord to produce different sweep and incidence angles for wing, by using rotating mechanism. Wind tunnel test was carried out at (Uپ‡=33.23m/s) for different swept angles and angles of attack.Comparisons were made between the predicted and experimental results. It is good and gave reasonable closeness. It was clear from the present investigation that the lift and drag characteristics for the forward swept wing are less in values compared with the swept back wing, therefore a forward swept wing can fly at higher speed corresponding to a pressure distribution associated for lower speed.

Thermal photons in QGP and non-ideal effects

We investigate the thermal photon production-rates using one dimensional boost-invariant second order relativistic hydrodynamics to find proper time evolution of the energy density and the temperature. The effect of bulk-viscosity and non-ideal equation of state are taken into account in a manner consistent with recent lattice QCD estimates. It is shown that the non-ideal gas equation of state i.e ε − 3 P ≠ 0 behaviour of the expanding plasma, which is important near the phase-transition point, can significantly slow down the hydrodynamic expansion and thereby increase the photon production-rates. Inclusion of the bulk viscosity may also have similar effect on the hydrodynamic evolution. However the effect of bulk viscosity is shown to be significantly lower than the non-ideal gas equation of state. We also analyze the interesting phenomenon of bulk viscosity induced cavitation making the hydrodynamical description invalid. It is shown that ignoring the cavitation phenomenon can lead to erroneous estimation of the photon flux.

One dimensional ordering of doping oxygen in [formula omitted] superconductors evidenced by X-ray diffuse scattering

X-ray diffuse scattering experiments on single CuO2 layer Hg high Tc superconductors (HgBa2CuO4+δ) near optimal doping level have revealed that the doping oxygen atoms of this system form very long and isolated chains (extending over 75 unit cells in average) in both tetragonal directions, with correlated transverse and longitudinal displacements of at least the nearby pairs of mercury atoms and copper atoms from two coupled CuO2 layers. Signs of incommensurate periodic lattice distortion have been also observed.

Protein dynamics: dancing on an ever-changing free energy stage

Protein dynamics: dancing on an ever-changing free energy stage

Microstructure evolution of 316L stainless steel micro components prepared by micro powder injection molding

Fabrication of micro components comprising of functional units of different dimensional order, ϕ100 μm, ϕ80 μm and ϕ60 μm, by micro powder injection molding is described in the paper. The microstructure is characterized for various microsize structures and substructures under different sintering conditions. The micro components are successfully molded, debound and sintered based on an in-house feedstock. Although sintered as an integral component, the microsize structure is at final stage sintering whereas the substructure is at intermediate stage sintering within the temperatures studied. The smallest microsize structures, ϕ60 μm, have the highest relative density. Higher surface area/volume ratio of the microsize structures is attributed to the advanced sintering. XPS results show that oxides on the debound micro components and consequent reduction products during hydrogen sintering attribute to the formation and progression of the observed dense layers.

A trichotomy of countable, stable, unsuperstable theories

Every countable, strictly stable theory either has the Dimensional Order Property (DOP), is deep, or admits an ‘abelian group witness to unsuperstability’. To obtain this and other results, we develop the notion of a ‘regular ideal’ of formulas and study types that are minimal with respect to such an ideal.

On deformation of functionally graded narrow beams under transverse loads

Solution is obtained for functionally graded (FG) narrow beams under plane stress condition of elasticity by using the mixed semi analytical model developed by Kant et al. (Int J Comput Methods Eng Sci Mech 8(3): 165–177, 2007a). The mathematical model consists in defining a two-point boundary value problem (BVP) governed by a set of coupled first-order ordinary differential equations (ODEs) in the beam thickness direction. Analytical solutions based on two dimensional (2D) elasticity, one dimensional (1D) first order shear deformation theory (FOST) and a new 1D higher order shear-normal deformation theory (HOSNT) are also established to show the accuracy, simplicity and effectiveness of the developed mixed semi analytical model. It is observed from the numerical investigation that the present mixed semi analytical model predicts structural response as good as the one given by the elasticity analytical solution which in turn proves the robustness of the present development.

Hybrid projective synchronization of chaotic fractional order systems with different dimensions

The hybrid projective synchronization of different dimensional fractional order chaotic systems is investigated in this paper. It is shown that the slave system can be synchronized with the projection of the master system generated through state transformation. Based on the stability theorem of linear fractional order systems, a suitable controller for achieving the synchronization is given. The hybrid projective synchronization between the fractional order chaotic system and hyperchaotic system is successfully achieved in both reduced order and increased order. The corresponding numerical results verify the effectiveness of the proposed method.

Topotactic reduction as a synthetic route for the preparation of low-dimensional Mn(II) oxide phases: The structure and magnetism of LaAMnO4-x (A = Sr, Ba)

Reaction of LaSrMnO(4) with CaH(2) at 420 degrees C yields LaSrMnO(3.67(3)). Raising the temperature to 480 degrees C yields the Mn(II) phase LaSrMnO(3.50(2)). Neutron powder diffraction data show both phases adopt body-centred orthorhombic crystal structures (LaSrMnO(3.67(3)), Immm: a = 3.7256(1) A, b = 3.8227(1) A, c = 13.3617(4) A; LaSrMnO(3.50(2)), Immm: a = 3.7810(1) A, b = 3.7936(1) A, c = 13.3974(3) A) with anion vacancies located within the equatorial MnO(2-x) planes of the materials. Analogous reactivity is observed between LaBaMnO(4) and CaH(2) to yield body-centred tetragonal reduced phases (LaBaMnO(3.53(3)), I4/mmm: a = 3.8872(1)A, c = 13.6438(2) A). Low-temperature neutron diffraction and magnetisation data show that LaSrMnO(3.5) and LaBaMnO(3.5) exhibit three-dimensional antiferromagnetic order below 155 K and 135 K respectively. Above these temperatures, they exhibit two-dimensional antiferromagnetic order with paramagnetic behaviour observed above 480 K in both phases. The origin of the low dimensional magnetic order and ordering of the anion vacancies in the reduced phases is discussed.