Anisotropic Lines Research Articles

Nano/Micro Natural Patterns of Hydrogels against Water Loss.

Water loss can be delayed by trapping it within a polymeric network, i.e. hydrogel. However, the dynamic response of natural materials has not been explained to maintain water levels relatively constant against varying environmental conditions. In this study, patterned polymeric materials formed on plant seeds are observed to provide effective water retention ability against repeated dehydration-rehydration procedures. The perpendicular line pattern (layer-by-layer stack) of the polymer films induces lateral line patterns (surface lines) by a typical wrinkling mechanism, which contributes to the characteristic water interaction. The anisotropic line patterns on the seed surface generate more hydrophilic properties over the isotropic patterns against drying-out. The matric potential (Ψm) of water through the line patterned gel matrix generally shows higher efficiency over isotropically patterned gels. Anisotropic lines (i.e., wrinkles) are one of the most abundant patterning procedures, thus they are a more advantageous function occurring in natural systems. This study sheds light on material design technologies to control water interaction in porous materials for various applications.

Diffusion of stochastic magnetic field lines with average poloidal magnetic component

We study the diffusion of stochastic isotropic and anisotropic magnetic field lines in turbulence with average poloidal magnetic field component. In the current work we employ the so-called DeCorrelation Trajectory method in order to compute the running and asymptotic diffusion coefficients of stochastic magnetic field lines with average poloidal magnetic field component. A modification of the diffusion coefficients is caused by the average magnetic field component parameter in the presence of trajectory trapping. We calculate the field line diffusion coefficients Dxx and Dyy for different values of the magnetic Kubo number K, the average magnetic field component parameter Kav and the anisotropy parameter Λ. Furthermore we compare our new findings with those already obtained in papers dealing with the calculus of the diffusion coefficients for a stochastic sheared magnetic field.

Strong anisotropic nodal lines in the TiBe family.

Using first-principles calculations and k·p model analysis, we find that Dirac nodal lines (DNLs) exist in low energy band structures of real materials of the body-centered cubic TiBe family. The nodal lines are protected by mirror reflection symmetries of the systems. The anisotropic electronic state interaction around the Fermi level produces a strong anisotropic quasi-square shape nodal line in the systems. Moreover, all the systems demonstrate drumhead surface states spanning a large energy window showing their potential in terms of high temperature superconductivity. The slight gap induced by spin-orbit coupling (SOC) indicates that materials of the TiBe family are promising candidates for future experimental studies on nontrivial topological semimetals.

Field-driven transition in the Ba1−xKxFe2As2 superconductor with splayed columnar defects

Through 2.6 GeV U irradiations, we have induced bimodal splayed columnar defects in Ba$_{1-x}$K$_x$Fe$_2$As$_2$ single crystals with splay angles, $\pm 5 ^\circ$, $\pm 10 ^\circ$, $\pm 15 ^\circ$, and $\pm 20 ^\circ$. Critical current densities through magnetization measurements were carefully evaluated, where a splay angle of $\pm 5 ^\circ$ brought about the highest $J_\mathrm{c}$. Mageto-optical images close to $T_\mathrm{c}$ indicates highly anisotropic discontinuity lines in the remnant state, and with anisotropy increasing with greater splay angles. Moreover, amongst those with splayed columnar defects, anomalous non-monotonic field dependences of $J_\mathrm{c}$ and $S$ with an extrema at some fraction of the matching field are observed. We discuss that such $J_\mathrm{c}$ enhancement arises from a field-driven coupling transition in which intervortex interactions reorganize the vortex structure to be accommodated into columnar defects, thereby increasing pinning at higher fields.

Abstract 186: Heart Disease Associated Lamin A/C Mutations and Resultant Defects in Cell and Nuclei Structure

Changes in cell organelle structure or shape, which can be associated with a variety of diseases, can be caused by inherited genetic mutations. For example, the progeria disease is associated with a mutation to the LMNA gene, and it leads to a devastating early aging and death. However, other LMNA gene mutations do not cause early aging, but instead have a more subtle effect with patients presenting only with heart disease symptoms. One way to study the mechanisms that lead to these differences is in vitro with patient specific cell-lines. Here we will present a study of 10 cell-lines negative for mutations or with four different types of LMNA mutations: 1) Hutchinson-Gilford progeria syndrome LMNA gene mutation, 2) LMNA splice-site mutation (c.357-2A>G , p.N120Lfs*5), 3) LMNA nonsense mutation (c.736 C>T, p.Q246X), and 4) LMNA missense mutation (c.1003C>T, p.R335W) in exon 6. Fibroblasts from each of these cells lines were cultured on either isotropic fibronectin or fibronectin patterned into anisotropic lines. The cells were then fixed and stained to visualize the nuclei, actin fibrils, and the underline remodeled fibronectin. To analyze this data, we applied existing algorithms to quantify the re-organization of actin in response to extracellular matrix cues by calculating both the actin and fibronectin orientational order parameter. Additionally, we have created a new algorithm to automatically identify nuclei defects, which is a known property of the progeria LMNA mutation. Using the new algorithm, it is possible to separately characterize the shape of normal and defective nuclei for each cell-line. Through this algorithm, we show the varied effects of the different mutations on the number of fibroblasts that present with nuclear defects and their properties. The current data is consistent with the known patient symptoms providing further avenues of study into the mechanisms triggered by these mutations. Furthermore, we probe whether the unique mechanical conditions present in the myocardium are responsible for the heart disease symptoms of some of the tested mutations.

The role of pedogenic overprinting in the obliteration of parent material in some polygenetic landscapes of Sicily (Italy)

Many soils older than the Holocene have experienced several changes, and possess properties that may be due to the complex effect of several stages of soil development; these soils are called polygenetic. It is still rather unclear, however, if, as time elapses, pedogenic processes tend to diverge generating different soils, or converge towards increasingly similar soils. We studied five pedons (37°60′N, 13°90′E) exposed to present weathering simultaneously since the Holocene but located on Upper Miocene or Holocene parent material. Their XRD and FTIR clay mineralogy reveal an overall homogeneity; smectites, calcite and gypsum reach the thermodynamic equilibrium, a slight undersaturation of the illitic phase occurs in all soil profiles. Also soil micromorphology confirms a general similarity: vertic features detected as anisotropic lines and aureoles occur in all soils. Net mass chemical fluxes, based on mean translocation values per profile, excluded vertical (depth to the soil profile) and horizontal (topographical positions of profiles) pedogenic domains. Here, we show that the elapsed time of weathering has obliterated the effects of past sea transgression, revealing the vertic character independently on the age of its parent material in the case of soils that develop from Holocene, Messinian and Tortonian deposits, with a rate of pedogenesis plausibly in the order of 1/10mm per year. The soils of today reveal a strong homogeneity, in particular, in the mineralogical composition of the very fine earth; twenty-five per cent kaolinite and 75% interstratified illite/smectite are independently inherited from the parent material and are thermodynamically very stable. Vertic properties here could be considered to be in a steady-state condition nevertheless they experienced significant environmental disturbance.

Revealing the Cu2+ ions localization at low symmetry Bi sites in photorefractive Bi12GeO20 crystals doped with Cu and V by high frequency EPR

The sites of incorporation of Cu2+ impurity ions in Bi12GeO20 single crystals co-doped with copper and vanadium have been investigated by electron paramagnetic resonance (EPR). While the X-band EPR spectra consist of a simple broad (ΔB ∼50mT) line with anisotropic lineshape, the W-band EPR spectra exhibit well resolved, strongly anisotropic lines, due to transitions within the 3d9–2D ground manifold of the Cu2+ ions. The most intense group of lines, attributed to the dominant Cu2+(I) center, displays a characteristic four components hyperfine structure for magnetic field orientations close to a 〈110〉 direction. The g and A tensor main axes are very close to one of the 12 possible sets of orthogonal 〈1−10〉, 〈00−1〉 and 〈110〉 crystal directions. Several less intense lines, with unresolved hyperfine structure and similar symmetry properties, mostly overlapped by the Cu2+(I) spectrum, were attributed to Cu2+(II) centers. The two paramagnetic centers are identified as substitutional Cu2+ ions at Bi3+ sites with low C1 symmetry, very likely resulting from different configurations of neighboring charge compensating defects.

Raman study of solvation in solutions of lithium salts in dimethyl sulfoxide, propylene carbonate and dimethyl carbonate

Raman study of cation and anion solvation in dimethyl sulfoxide, propylene carbonate and dimethyl carbonate solutions of six lithium salts has been performed in the concentration range from 0.05 to 0.25 molar fraction of a salt. The dependences of the amount of the solvent particles involved in dimerization, hydrogen bonding, and solvation have been determined, and the mean solvation numbers have been found. It is concluded that in all solutions studied, notwithstanding the differences in the physical properties of the solvent and in the structure of the anion, both the lithium cation and the anion solvation equilibria are quantitatively similar. In all cases, solvation numbers of cations are close to two and do not vary with the growth of concentration. In particular, in molten LiX·4S solvates, LiS4+ entities expected from the phase diagrams do not exist. It has been found that for the solvent molecules in dimers and in solvation spheres, non-coincidences between vibrational frequencies of isotropic and anisotropic lines, ΔνNCE=νaniso−νiso are of opposite signs signifying that the mutual orientation of molecules is different. In all systems studied, solvation numbers of anions decrease if the salt content is growing and are close to four in concentrated solutions. These striking similarities in the structure and concentration of solvated entities clearly signify that solvation phenomena have no decisive importance in determining the properties of salt systems.

Family of paramagnetic centers of Ce3+ ions in yttrium aluminum garnet

The electron paramagnetic resonance (EPR) spectra of Ce3+ ions in single crystals of yttrium aluminum garnet have been investigated. It has been found that, in addition to the usually observed EPR signals of Ce3+ ions located in the regular environment at dodecahedral sites of the crystal lattice, the spectra contain a group of less intense anisotropic lines with g-factors close to the corresponding parameters of Ce3+ ions in the regular environment. It has been concluded that the observed satellite lines belong to the family of Ce3+ ions in the immediate vicinity of which there are permutation defects that lead to a change in the strength and symmetry of the crystal field in the vicinity of the paramagnetic center.

Selecting printed circuit board parameters using swarm intelligence to minimize crosstalk between adjacent tracks

SUMMARYThe purpose of this paper is to provide a numerical tool for designers in order to help reduce the unwanted coupling between nearby transmission lines on printed circuit boards. This is accomplished using particle swarm optimization technique, where the coupling factor between adjacent lines is used as the fitness function. The coupling factor is computed based on conformal mapping equations of capacitances for even and odd modes of different types of transmission lines, including microstrip and strip lines. Anisotropic, isotropic, asymmetric, and symmetric coupled lines are considered. The S‐parameters of the optimized and unoptimized configurations are computed from the conformal mapping equations and also using the full‐wave electromagnetic simulator IE3D, which is based on the method of moments, where an agreement can be observed between the two results. Different examples are presented here that show the effectiveness of this method in reducing the coupling factor. A Matlab program is written to harness particle swarm optimization to find optimum solutions. Copyright © 2014 John Wiley & Sons, Ltd.

Low temperature preparation and characterization of In 1− xLn xBO 3 ( x = 0.0 and 0.05; Ln = Gd, Eu, Dy and Sm): ESR of In 0.95Gd 0.05BO 3 and emission of In 0.95Eu 0.05BO 3

Indium borate and rare earth substituted indium borates (In 1− x Ln x BO 3 ( x = 0.0 and 0.05; Ln = Gd, Eu, Dy and Sm)) are prepared at low temperature by metathesis reaction using InCl 3, LnCl 3 and NaBO 2. They are characterized by powder XRD and infrared spectroscopy. All the compositions (In 1− x Ln x BO 3) crystallize in hexagonal lattice with calcite structure. These borates gave characteristic IR vibrations of planar BO 3 group. Spin-Hamiltonian parameters for Gd 3+ are deduced from room temperature electron spin resonance spectrum of In 0.95Gd 0.05BO 3. The electron spin resonance spectrum of In 0.95Gd 0.05BO 3 gave several anisotropic lines with g > 2.0. The ESR spectrum of the sample belongs to the “intermediate” category with 1/4 < H CF/ hν < 1. The local symmetry of Eu 3+ in In 0.95Eu 0.05BO 3 is obtained from its emission spectrum. The R/O ratio of In 0.95Eu 0.05BO 3 suggests the occupation of In 3+ site by Eu 3+ with near symmetric octahedral geometry.

A pedostratigraphic marker in the geomorphological evolution of the Campanian Apennines (Southern Italy): The Paleosol of Eboli

The Paleosol of Eboli is interbedded within an Early Pleistocene coarse alluvial succession, the Eboli Conglomerates, located in the Campanian Apennines (Southern Italy), infilling the morphostructural depression of the Sele River Plain. Quaternary climatic changes and related morphodynamic response were investigated using a multidisciplinary (geomorphological, sedimentological and pedological) approach. The alluvial sequence of the Eboli Conglomerates shows remarkable vertical changes, marked by clear erosional discontinuities that identify four stacked formations called, from the bottom, Fontana del Fico, Colle Mancuso, Castelluccia, and S. Anna formations. The clastic facies of these formations are mainly indicative of an alluvial fan environment, with most sediments emplaced by flooding of distributary streams. The Paleosol of Eboli is formed at the top of the Castelluccia formation. We investigated its morphological, physical, chemical, micromorphological, and mineralogical properties. Many discontinuities appear in the field due to various erosional events that are related to hillslope dynamics. Each of these events was followed by the emplacement of new and different colluvial deposits that were derived from upslope and were subsequently affected by pedogenesis. All the horizons of the Paleosol of Eboli have reddish and brown matrix colours, secondary carbonate, angular blocky structure, and clayey texture. On the basis of the field data and chemical and physical analysis, three different pedogenetic cycles can be distinguished in the Paleosol of Eboli. These cycles depict differing degrees of pedogenic expression depending on water regime and duration of pedogenesis. The micromorphology showed the presence of eluvial tongues, Fe dynamics (coatings, segregations), vertic features (optically anisotropic lines in the soil matrix), and pedorelicts. Kaolinite is the most abundant clay mineral, but vermiculite and illite are also present. The Fe minerals, especially the hematite/goethite ratio, have provided a new approach to understand the main paleoclimatic changes through the studied sequence. The overall pedogenetic scenario depicts a highly weathered environment (disordered kaolinite, Fe oxides, low Feo/Fed ratio, depletion zones), characterized by marked climatic seasonality (witnessed by vertic properties) and abundant rainfall (depletion zones). The general scenario is coherent with a highly weathered subtropical environment that probably occurred during MIS-25, based on age control. The widespread outcrop pattern, consistent stratigraphic position, thickness ranging from 1 to 5 m, and the uniformity of pedological features of the Paleosol of Eboli make it clearly recognizable in the field and allow us to consider the Paleosol of Eboli a reliable pedostratigraphic marker.

THE ACTION OF FINITE ORTHOGONAL GROUPS IN CHARACTERISTIC 2 ON THE SET OF ANISOTROPIC LINES

We prove that the permutation representation of the finite orthogonal group $\Omega^{\varepsilon}(n,q)$ , where $\varepsilon=+$ or $-$ , on the set of anisotropic lines is multiplicity-free, if q is a power of 2 and $n\ge 6$ is even. This result is established by giving a description of orbitals of this action. The rank of this action is $(q^2+2q)/2$ if $\varepsilon=+$ and $n=6$ , and $(q^2+2q+2)/2$ otherwise. Moreover, we compute the subdegrees of the orbitals of $\Omega^{\varepsilon}(n,q)$ .

An internally consistent integration method for critical state models

A new procedure to integrate critical state models including Cam–Clay and modified Cam–Clay is proposed here. The proposed procedure makes use of the linearity of the virgin isotropic compression curve and the parallel anisotropic consolidation lines in e–ln p space which are basic features of the formulation of critical state models. Using this algorithm, a unique final stress state may be found as a function of a single unknown for elastoplastic loading. The key equations are given in this article for the Cam–Clay and modified Cam–Clay models. The use of the Newton–Raphson iterative method to minimize residuals and obtain a converged solution is described here. This new algorithm may be applied using the assumptions of linear elasticity or non-linear elasticity within a given loading step. The new algorithm proposed here is internally consistent and has computational advantages over the current numerical integration procedures. Numerical examples are presented to show the performance of the algorithm as compared to other integration algorithms. Published in 2005 by John Wiley & Sons, Ltd.

Thermodynamics of soft anisotropic contact lines.

Contact lines arising from the intersection of interfaces between liquids and nematic liquid crystals are representative models of soft anisotropic contact lines. This paper presents the thermodynamics of soft anisotropic contact lines and the derivation of the one dimensional (1D) Gibbs-Duhem adsorption equation. Consistency between the 1D Gibbs-Duhem equation and the classical equations of lineal nematostatics is shown. Using a phase space that takes into account thermodynamics, liquid crystalline order, and geometric variables, the generalized nematic line Gibbs-Duhem equation reveals the presence of couplings between curvature, torsion, adsorption, temperature, and average molecular orientation. Merging the thermodynamic analysis with nematostatics results in a model for contact line shape and orientation selection. The ability of an adsorbed solute to orient the director and to bend and twist the contact line is predicted. The thermodynamic origin of preferred orientation at a straight contact line is established.

Line tension vector thermodynamics of anisotropic contact lines.

Multiphase materials with intersecting diving surfaces give rise to contact lines. A line tension vector thermodynamics formalism is developed and used to analyze contact line problems in the presence of anisotropy, taking into account two elastic modes: change in contact line length and change in contact line orientation. Using this formalism, the contact line-shape equation is derived, and the renormalization of the line tension due to anisotropy is characterized. The correspondence and analogies between the shape equation for anisotropic surfaces (Herring equation) and the shape equation for contact lines is established. Line energies for nematic liquid crystals, representative of generic anisotropic contact lines, are used to derive a shape equation that takes into account ambient orientation effects. It is found that anisotropic line tension may promote bending and chiral modes to avoid unfavorable orientations of the contact line with respect to the ambient nematic ordering.

ESR Study on YBiPt compound doped by Er 3+ and Gd 3+

The compound YBiPt doped by Er and Gd has been studied by ESR technique in the X and Q-bands between 4 and 300 K. Two anisotropic lines with hyperfine peaks due to the interaction between electronic and nuclear spins of 167Er 3+ (I= 7 2 ) isotope have been observed below 30 K. Dysonian line shape of the Er and Gd ESR signals shows a metallic character of the conductivity in studied samples as well. Computer modeling has shown that these lines belong to the two allowed transitions in the quadruplet ground state of Er +3 ions in the ligand crystal field of cubic symmetry. The values of crystal field parameters B 4=−5.68×10 −4 cm −1 and B 6=−6.64×10 −6 cm −1 have been extracted. An additional isotropic line with g=1.99 observed in both frequency bands has been attributed to the Gd impurities. The temperature dependence of peak-to-peak linewidth of Gd 3+ signal has been well described by the Korringa relaxation of Gd magnetic moments to the itinerant electrons, d Hpp= a+ bT. The value of exchange constant J sf have been estimated from the Korringa slope of b=0.12 Oe/K. The intensity of Gd 3+ signal, which obeys the Curie's law for paramagnetic ions at lowest temperatures, deviates from this law at temperatures higher than 140 K.

ESR studies on Er3+‐doped YBiPt compound

AbstractThe semi‐metallic cubic compound YBiPt doped by Er3+ (4f11) has been studied by ESR technique between 4 and 300 K. X‐band and Q‐band measurements have been performed. The angular dependence of the ESR spectra on the crystal orientation with respect to the static magnetic field has been measured. Two anisotropic lines with hyperfine peaks coming from the interaction between electronic and nuclear spins of 167Er3+ (I = 7/2) isotopes have been observed below 30 K in the spectra. Computer modeling showed that these lines are the ESR signals from the quadruplet ground state of Er3+ ions in the cubic crystal field. The values of crystal field parameters B4 = –5.68 × 10–4 cm–1 and B6 = –6.64 × 10–6 cm–1 have been extracted. Also an isotropic line near g = 2 have been observed in both frequency bands. Dysonian lineshape of the spectra components due to the skin‐depth effect shows the conducting property of the sample under study. The temperature dependence of the spectra intensity obeys the well‐known Curie law for paramagnetism arising from the unpaired electrons of Er3+ ion.

Electron paramagnetic resonance in the quasi-two dimensional magnetic ludwigite Fe3O2BO3

We report an EPR study of the quasi-two dimensional oxide Fe3O2BO3 which shows a structural transition at 283 K, an antiferromagnetic transition at 112K and weak ferromagnetism below 73 K. The single crystals show three strongly anisotropic lines with different temperature dependences of their widths and resonance fields. The results are discussed in relation with the different phase transitions and with the Wigner glass phase which appears between ~112 K and ~200 K.

Phosphorus site after CIRA implantation of type IIa diamond

Abstract A set of type IIa diamond crystals was processed by cold implantation and rapid annealing at 1050°C ex situ annealing at 1400°C and investigated by ESR measurement. The ESR spectra of CIRA and post-annealed samples show an isotropic line at g =2.003, a set of anisotropic hyperfine lines, and a pair of isotropic hyperfine lines centred at g =2.003 with Δ H =28 G. The intensities of each signal increase with the implantation dose. After the second annealing step the intensities of all signal was reduced, excepted for the centre with Δ H =28 G which increases. This signal was ascribed to a new centre related to phosphorus, probably neutral substitutional phosphorus.