Higher Anisotropy Values Research Articles

Buccal dental microwear texture and catarrhine diets.

Two-dimensional dental microwear analyses on occlusal and nonocclusal enamel surfaces have been widely applied to reconstruct the feeding behaviors of extant primates and to infer ecological adaptations in fossil hominins. To date, analyses of dental microwear texture, using three-dimensional, Scale-Sensitive Fractal Analysis approaches has only been applied to occlusal surfaces. Here, for the first time, we apply this 3D proxy to buccal enamel surfaces of catarrhine primates of known feeding ecologies to assess the utility of nonocclusal microwear texture variables as indicators of dietary habits. Buccal microwear texture attributes were collected from high-resolution second molar casts in a sample of seven extant African catarrhine taxa with differing dietary behaviors. A white-light confocal microscope with a 100× objective lens was used to record six microwear texture variables that assess complexity, anisotropy, heterogeneity, and textural fill volume. The physical properties and variation in hardness of ingested foods is reflected by significant differences in the microwear variables on buccal enamel surfaces between species, which is in agreement with early reports using 2D microwear signatures of the same samples. Species that consume hard brittle items showed high buccal enamel complexity and low anisotropy values, while folivorous species that consume tough foods revealed high anisotropy and low complexity enamel patterns. Buccal microwear texture analysis on enamel surfaces clearly reflects diet-related variation in nonhuman primates. Our findings indicate that microwear texture attributes on nonworking enamel surfaces provide an alternative procedure for reconstructing dietary behavior when wear facets on occlusal surfaces are lacking.

Dental microwear texture analysis of extant koalas: clarifying causal agents of microwear

AbstractMicroscopic wear patterns on teeth, that is, dental microwear, are capable of recording observed dietary behaviour in a diversity of extant and extinct animals. However, recent work has questioned the utility of dental microwear at clarifying dietary behaviour, instead suggesting that dental microwear textures are reflective of grit consumed and not the dietary properties of ingested food. Some suggest that dental microwear cannot reflect the textural properties of vegetation consumed because phytoliths are too soft to form microwear. Koalas (Phascolarctos cinereus) are model organisms for examining dental microwear formation because they consume a specialized diet consisting almost exclusively of eucalyptus leaves, which notably lack phytoliths. Here, we assess if koala dental microwear records a diet consistent with the consumption of tough leaves – despite the absence of phytoliths in their primary food source. Dental microwear texture data of koalas are consistent with tough folivorous diets, with high anisotropy values indistinguishable from folivorous primates and grazing bovids. However, koalas have significantly higher complexity (indicative of hard object feeding) than the folivorous primate Alouatta palliata, and are indistinguishable in this variable from mixed feeding and browsing bovids. While higher complexity values in koalas may result from increased dust and/or grit on the landscape in comparison to folivores that occur in wetter environments, it may also result from the mastication of woody browse. We also determined that complexity and textural fill volume are not significantly greater in drier environments – as one would predict if grit was the major contributor to dental microwear formation. Koalas may instead be selecting softer younger leaves in drier regions where water is more limited. Collectively, microwear associated with tough object feeding can be formed in the absence of phytoliths and grit may interact with food to form microwear reflective of diet, as opposed to overprinting dietary signals.

Microwave absorption studies of magnetic sublattices in microwave sintered Cr3+ doped SrFe12O19

The partial substitution of Fe3+ by Cr3+ in strontium hexaferrite has shown to be an effective method to tailor anisotropy for many novel microwave applications. Some basic studies have revealed that this substitution leads to unusual interactions among the magnetic sublattices of the hexaferrite. In order to investigate these interactions, Cr3+ doped SrCrxFe12−xO19 (x=0.0, 0.1, 0.3, 0.5, 0.7 and 0.9) (m-type) hexaferrites were prepared by microwave-hydrothermal (m-H) method and subsequently sintered at 950°C/90min using microwave furnace. The magnetic hysteresis (m-H) loops revealed the ferromagnetic nature of nanoparticles (NPs). The coercive field was increasing from 3291Oe to 7335Oe with increasing chromium content. This resulting compacts exhibited high squareness ratio (Mr/Ms–80%). The intrinsic coercivity (Hci) above 1,20,000Oe and high values of magnetocrystalline anisotropy revealed that all samples are magnetically hard materials. A material with high loss as well as high dielectric constant may be desired in applications such as electromagnetic (EM) wave absorbing coatings. The room temperature complex dielectric and magnetic properties (ε′, ε′′, µ′ and µ′′) of Cr3+ doped SrFe12O19 were measured in X-band region. The frequency dependent dielectric and magnetic losses were increasing to large extent. The reflection coefficient varied from −16 to −33dB at 10.1GHz as Cr3+ concentration increased from x=0.0 to x=0.9. Ferromagnetic resonance spectra (FMR) were measured in the X-band (9.4GHz), linewidth decreases with chromium concentration from 1368 to 752Oe from x=0.0 to x=0.9, which is quite low compared to commercial samples. We also have detailed origins of the FMR linewidth broadenings in terms of some important theoretical models. These results show that chromium doped strontium hexaferrites are useful for microwave absorption in the X-band frequency and also have potential for use in low frequency self-biased microwave/millimeter devices such as circulators and isolators.

Synthesis, Surface Properties and Effect of an Amino Acid Head Group of 11‐(2‐Methoxy‐4‐vinylphenoxy)undecanoicacid‐Based Anionic Surfactants

AbstractOur present research describes the surface properties of three biobased anionic surfactant synthesized from vinylguaiacol and 11‐bromo undecanoic acid. To further improve its hydrophobicity and bioavailability, amino acid head group incorporation was carried out. All these synthesized compounds were thoroughly characterized using NMR and mass spectroscopy. The performance properties such as foaming, wetting, emulsification value and calcium tolerance were evaluated. The studied surfactants possess excellent emulsion stability and moderate calcium tolerance as compared to commercially available surfactant sodium lauryl sulfate (SLS). The micelle formation and the thermodynamics involved at the air–water interface were estimated from surface tension measurements. These surfactants showed a higher tendency towards adsorption at the air–water interface than micellization. Dynamic light scattering and steady state fluorescence anisotropy study were carried out to shed light on the bulk micellization properties of the synthesized surfactant. Along with spherical micelles of <5 nm size, larger aggregates (35–84 nm) were observed with higher anisotropy values. FESEM images further confirmed the larger spherical micelles formed by these surfactants. The surfactants formed chiral aggregates above the critical micelle concentration as indicated by circular dichroism spectra. These surfactants may be suitable candidates for additives to detergents to improve their calcium tolerance especially in the case of hard water. Furthermore, a low foaming ability along with high emulsion stability may find these surfactants to be better replacement of the conventional surfactant used as emulsifiers in many industrial applications.

Field orientation dependence of magnetization reversal in thin films with perpendicular magnetic anisotropy

The magnetization reversal process of hexagonal-close-packed (hcp) (0001) oriented Co and Co90Ru10 thin films with perpendicular magnetic anisotropy (PMA) has been studied as a function of temperature and applied magnetic field angle. Room temperature pure cobalt exhibits two characteristic reversal mechanisms. For angles near in-plane field orientation, the magnetization reversal proceeds via instability of the uniform magnetic state, whereas in the vicinity of the out-of-plane (OP) orientation, magnetization inversion takes place by means of domain nucleation. Temperature dependent measurements enable the modification of the magnetocrystalline anisotropy and reveal a gradual disappearance of the domain nucleation process during magnetization reversal for elevated temperatures. Ultimately, this suppression of the domain nucleation process leads to the exclusive occurrence of uniform state instability reversal for all field orientations at sufficiently high temperature. Comparative magnetic measurements of Co90Ru10 alloy samples allow the identification and confirmation of the high temperature remanent magnetization state of cobalt as an OP stripe domain state despite the reduction of magnetocrystalline anisotropy. Detailed micromagnetic simulations supplement the experimental results and corroborate the physical understanding of the temperature dependent behavior. Moreover, they enable a comprehensive identification of the complex energy balance in magnetic films with PMA, for which three different magnetic phases occur for sufficiently high anisotropy values, whose coexistence point is tricritical in nature.

Unprecedented high fluorescence anisotropy in protic solvents: Hydrogen bond induced solvent caging?

Atypical high fluorescence anisotropy has been revealed in protic solvents for excited state intramolecular proton transfer (ESIPT) prone 3-hydroxyflavone and some of its hydroxy derivatives. In non-protic solvents, however, the anisotropy values are low. The low and alike anisotropy values of 3-methoxyflavone in all the studied solvents and other experimental evidences ascribe the formation of hydrogen bond induced cage-like structures in case of the hydroxy compounds involving the probe and the solvent molecules to be responsible for the high values of fluorescence anisotropy in protic media.

Microstructure, texture and orientation dependent flow behavior of hot rolled and annealed ternary Ni–16Cr–16Mo, Ni–16Cr–4W and Ni–16Cr–8Fe alloys

Present work describes a correlation among microstructure, texture and mechanical properties anisotropy of ternary Ni–16Cr–16Mo, Ni–16Cr–4W and Ni–16Ce–8Fe alloys in hot rolled and annealed condition. The evolution of microstructures of the alloys has been explained based on stacking fault energy and presence of texture components in the material. The alloys Ni–16Cr–16Mo, Ni–16Cr–4W and Ni–16Cr–8Fe exhibit low, moderate and high values of in-plane anisotropy, respectively. The anisotropy index values of alloys Ni–16Cr–4W, Ni–16Cr–8Fe and Ni–16Cr–16Mo are moderate, high and moderate, respectively. The overall intensity and extent of homogeneity of the {111}-fiber have marked influence on both the σYS and uniform elongation values. The alloys reveal the presence of two slopes in true plastic stress–strain curves and follow typical Ludwigson relation. The deformation behavior in low strain regime is associated with formation of uniform and finely spaced slip lines within the grains as a result of very small fraction of strain localization. On the other hand, main attributes of high strain regime are penetration of a few coarse slip lines across the grain boundaries along with large volume fractions of deformation twins and strain localization. The overall nature of differential curves of all the alloys is quite different although these curves consist of typical three stages (I, II and III) of work hardening. The nature of differential curves indicates different deformation mechanisms associated with these alloys during uniform elongation. Uniform elongation values of the alloys have been explained based on dynamic recovery coefficient using Kocks–Mecking–Estrin analysis.

P‐115: New Photoalignment Material: Azimuthal Anchoring Energy Decreases at Very High Photo‐Induced Order Parameters

We developed new azo‐dye photoalignment material with extremely high values of photoinduced anisotropy: order parameter S∼0.85, dichroic ratio DR∼17.5. Experiment reveals decrease of azimuthal anchoring energy for highly oriented azo‐dye layers, contradicting with regular expectations. High quality patterned λ/4 retarder based on RM mesogens with ∼3 µm pattern disclination width are obtained.

Let’s Twist (the S4) Again

Let’s Twist (the S4) Again

The relationship between uncinate fasciculus white matter integrity and verbal memory proficiency in children.

During childhood, verbal learning and memory are important for academic performance. Recent functional MRI studies have reported on the functional correlates of verbal memory proficiency, but few have reported the underlying structural correlates. The present study sought to test the relationship between fronto-temporal white matter integrity and verbal memory proficiency in children. Diffusion weighted images were collected from 17 Black children (age 8-11 years) who also completed the California Verbal Learning Test. To index white matter integrity, fractional anisotropy values were calculated for bilateral uncinate fasciculus. The results revealed that low anisotropy values corresponded to poor verbal memory, whereas high anisotropy values corresponded to significantly better verbal memory scores. These findings suggest that a greater degree of myelination and cohesiveness of axonal fibers in uncinate fasciculus underlie better verbal memory proficiency in children.

Room temperature coercivity and interaction effects in L10 FePt nanoparticles

FePt alloy systems in the L10 phase are characterized by high anisotropy values that lead to exceptionally high coercive fields, making them a primary candidate for high density data storage. In this paper, we report the synthesis of L10 FePt nanoparticles by thermal annealing of chemically disordered FePt nanoparticles. The high degree of ordering and high coercivity achieved in these systems is further studied using Monte Carlo simulations by incorporating the effects of anisotropy, interactions, and disorder, with a view to understand the role of these interactions. A comparison of the simulation results with the experiment results also helps us to estimate an anisotropy value of ∼2.25–2.5 MJ m−3.

Hard wear-resistant coatings with anisotropic thermal conductivity for high thermal load applications

High thermal load applications such as high speed dry cutting lead to high temperatures in the coated tool substrate that can soften the tool and high temperature gradients that can put stress on the coating/tool interface. In this work, theoretical considerations are presented for multilayer and graded protective coatings that can induce a significant anisotropy in their thermal conductivity. Solution of the heat equation shows that anisotropy of thermal conductivity has the potential to reduce temperatures and temperature gradients arising due to brief, localized heat at the coating surface (“hot-spots”). Experimental realization of high anisotropy is demonstrated in TiN/AlCrN multilayer coatings with variable layer thickness. In the coating with 50 nm bilayer periodicity, the highest anisotropy was obtained with a value of κ||/κ⊥=3.0±0.9. Time-domain thermoreflectance is used to measure in-plane and cross-plane thermal conductivity of fabricated coatings. The observed high values of anisotropy of thermal conductivity are compared with theoretical predictions and its realisation is discussed with regard to the coating microstructure.

Mechanical properties anisotropy of cold rolled and solution annealed Ni–20Cr–8Fe alloy

Present work describes a correlation amongst texture, in-plane anisotropy in tensile properties and yield locus in Ni–20Cr–8Fe alloy. The alloy exhibits high and moderate values of in-plane anisotropy and anisotropy index, respectively. This has been attributed to the presence of moderate overall intensity of texture as well as partially recrystallized microstructure. The tensile properties evaluated in five sample directions, namely the 0° (longitudinal or L), 22.5°, 45°, 67.5° and 90° (transverse or T) to the rolling direction, display two slopes in true plastic stress–strain curve and follow a Ludwigson relation. At low strains, sample displays the presence of annealing twins and less strain localization (1.5–3.5° boundaries) while the formation of deformation twins and high strain localization are observed in high strained region. The 67.5° orientation sample shows relatively low ductility and low work hardening exponent. This has been explained using Kock–Mecking–Estrin analysis based on higher degree of dynamic recovery/glide softening and fluctuations in work hardening rate during stage II.

Superparamagnetic Behavior of MFe2O4 Nanoparticles and MFe2O4/SiO2 Composites (M: Co, Ni).

Two kinds of nanosized ferrite systems have been prepared: MFe2O4 nanoparticles and MFe2O4/SiO2 (M: Co, Ni) nanocomposites with different ferrite particle sizes. Magnetic measurements have been done for both ferrite systems in the 5–700 K temperature range, and the silica matrix effect on the magnetic behavior has been studied. Whereas CoFe2O4 samples are characterized by high anisotropy values, NiFe2O4 particles seem to be magnetically soft, which may favor the dipolar interactions. The silica matrix avoids all kinds of particle interactions that modify the magnetic behavior. Therefore, in 2–5 nm embedded Co-ferrite particles, a decreasing HC value with the increasing particle size is not observed. This almost constant HC value indicates that interactions between surface spins of different particles are absent for this particle size range. In the case of Ni-ferrite particles, the dipolar interactions between bulk particle moments are minimized due to the presence of the SiO2 matrix.

Phase-field simulations and geometrical characterization of cellular solidification fronts

The structure and dynamics of cellular solidification fronts produced during the directional solidification of dilute binary alloys are studied by phase-field simulations. A quantitative phase-field model in conjunction with a multi-scale simulation algorithm allows us to simulate arrays with 10–40 cells in three dimensions on time scales that are long enough to allow for a significant reorganization of the array. We analyze the geometry of the complex two-phase structure (mushy zone) and extract the fraction of solid and the connectivity of the two phases as a function of depth. We find a transition from stable arrays at high values of the crystalline anisotropy to unsteady arrays at low anisotropy that continuously exhibit tip splitting and cell elimination events.

Photo- and thermal-processing of azobenzene-containing star-shaped liquid crystals

A new class of star-shaped, liquid crystalline, low-molecular weight compounds functionalized with photochromic azobenzene and mesogenic groups was investigated in terms of light-induced anisotropy. The behaviour of the materials under the action of light with simultaneous or subsequent thermal treatment was examined with respect to the induction of anisotropy. The unconventional UV light treatment prior to the irradiation with linearly polarized light allowed induction of very high values of anisotropy (D = 0.77) at room temperature. Moreover, the simultaneous action of light and temperature led to the induction of higher values of dichroism in comparison with anisotropy generated by the standard procedure. Subsequent thermal treatment led to dewetting and the formation of 3D macroscopic stripe- and dome-like structures for one of the investigated compounds. Despite photoinduction of anisotropy by a single beam, the formation of polarization and surface relief gratings by two-beam interference pattern was also investigated.

Goniometric measurements of thick tissue using Monte Carlo simulations to obtain the single scattering anisotropy coefficient

The scattering anisotropy, g, of tissue can be a powerful metric of tissue structure, and is most directly measured via goniometry and fitting to the Henyey-Greenstein phase function. We present a method based on an independent attenuation measurement of the scattering coefficient along with Monte Carlo simulations to account for multiple scattering, allowing the accurate determination of measurement of g for tissues of thickness within the quasi-ballistic regime. Simulations incorporating the experimental geometry and bulk optical properties show that significant errors occur in extraction of g values, even for tissues of thickness less than one scattering length without modeling corrections. Experimental validation is provided by determination of g in mouse muscle tissues and it is shown that the obtained values are independent of thickness. In addition we present a simple deconvolution-based method and show that it provides excellent estimates for high anisotropy values (above 0.95) when coupled with an independent attenuation measurement.

Development of Transverse Fault along North Almora Thrust, Kumaun Lesser Himalaya, India: A Study Based on Field and Magnetic Fabrics

Abstract Along the North Almora Thrust (NAT) in the Kumaun Lesser Himalaya, a zone of mylonitic rocks has developed due to strain localization during the tectonic emplacement of the Almora Nappe over the Lesser Himalayan Sequence. This zone is referred here as the NAT zone (NATZ) that is dissected by faults, which are transverse to the Himalayan orographic trend and are known as seismically active structures. Trending NNW-SSE these are the Chaukhutiya and Raintoli faults. Two E-W oriented subsidiary brittle faults across the Chaukhutiya Fault are also recognized. Based on the field study and magnetic fabric analysis an attempt has been made to evaluate the deformation and kinematic history of northeastern margin of the Almora Nappe superposed by the Chaukhutiya faulting that coincides with northeastern margin of the NAT. Field study reveals brittle-ductile and brittle regimes of deformation along the Chaukhutiya Fault. Away from the NAT variable attitudes (E-W or ENE-WSW with gentle dip) of field foliation and axial planes of folds are observed, whereas at and near the NAT the attitudes of beds, including curved lithounits, are steeply dipping and are oriented parallel with the NNW-SSE trending NAT. Curvature in fold hinge line and discontinuous occurrence of lithounits are observed along the fault. Anisotropy of Magnetic Susceptibility (AMS) study of the rocks was carried out. It reveals that the anisotropy is controlled mostly by paramagnetic minerals, whereas ferromagnetic minerals have played a minor role. High temperature demagnetization through hysteresis curves has yielded negligible contribution of ferromagnetic minerals. The steep magnetic foliation is interpreted to be on account of NE-SW oriented progressive regional compression. Moreover, the magnetic foliation is inferred to represent a secondary foliation due to superimposition on primary foliation. Analyses of AMS and structural data indicate that the Chaukhutiya Fault has a strike-slip right lateral displacement including rotational component. AMS results reveal high anisotropy value (Pj) at the surface trace of the NAT and low anisotropy (Pj) away from it. Variable style of deformation is observed along the transverse fault length.

Confocal Fluorescence Anisotropy and FRAP Imaging of α-Synuclein Amyloid Aggregates in Living Cells

We assessed the intracellular association states of the Parkinson's disease related protein α-synuclein (AS) in living cells by transfection with a functional recombinant mutant protein (AS-C4) bearing a tetracysteine tag binding the fluorogenic biarsenical ligands FlAsH and ReAsH, The aggregation states of AS-C4 were assessed by in situ microscopy of molecular translational mobility with FRAP (fluorescence recovery after photobleaching) and of local molecular density with confocal fluorescence anisotropy (CFA). FRAP recovery was quantitative and rapid in regions of free protein, whereas AS in larger aggregates was>80% immobile. A small 16% recovery characterized by an apparent diffusion constant of 0.03–0.04 µm2/s was attributed to the dynamics of smaller, associated forms of AS-C4 and the exchange of mobile species with the larger immobile aggregates. By CFA, the larger aggregates exhibited high brightness and very low anisotropy, consistent with homoFRET between closely packed AS, for which a Förster distance (R o) of 5.3 nm was calculated. Other bright regions had high anisotropy values, close to that of monomeric AS, and indicative of membrane-associated protein with both low mobility and low degree of association. The anisotropy-fluorescence intensity correlations also revealed regions of free protein or of small aggregates, undetectable by conventional fluorescence imaging alone. The combined strategy (FRAP+CFA) provides a highly sensitive means for elucidating both the dynamics and structural features of protein aggregates and other intracellular complexes in living cells, and can be extended to other amyloid systems and to drug screening protocols.

Diagnostic possibility of diffusion tensor imaging for the evaluation of myometrial invasion in endometrial cancer: An ex vivo study

To investigate the feasibility of magnetic resonance imaging (MRI) diffusion tensor imaging (DTI) for evaluating the myometrial invasion of uterine endometrial cancer. Twelve specimens of uterine endometrial cancer were obtained. The depth of myometrial invasion was classified as stage E (limited to the endometrium; n = 4), stage S (superficial invasion of less than 50% of the myometrium; n = 5), or stage D (deep invasion of greater than 50% of the myometrium; n = 3). The specimens were fixed in 10% formalin and stored at 4°C before imaging. At 15 hours after fixation, MRI was performed using a 4.7-T experimental imager/spectrometer system. We found a high fractional anisotropy (FA) value zone (anisotropic zone) at the myometrium adjacent to the tumor on FA maps of histopathological stage S and stage D cancers, whereas the anisotropic zone did not exist in stage E cancers. Histopathological analysis showed that compared to the other regions, the anisotropic zone had tightly packed stromal tissue. The disruption of the anisotropic zone was consistent with myometrial invasion. Our ex vivo study suggests that DTI might be a useful tool for the diagnosis of myometrial invasion of uterine endometrial cancer ex vivo.