Anisotropy Values Research Articles

A DFT study: Tailoring opto-electronic and thermoelectric performance of K2SeX6 (X = Cl, Br) double perovskites for solar cell advancements

Density functional theory (DFT) has been used to examine the structure, optoelectronic, elastic, and thermoelectric characteristics of K2SeX6 (X= Br, Cl) utilizing the full potential linearized augmented plane wave (FP-LAPW). The examined double perovskites (DPs) appeared to feature indirect band gaps, according to the electronic band structure plots. K2SeX6 (X= Cl, Br) have computed shear anisotropy values of 0.55 and 0.54, respectively, indicating they are anisotropic materials. The materials' computed Poisson's ratios of 0.25 and 0.26 suggest that they are naturally ductile. According to the band structure plots, the examined DPs appear to feature indirect band gaps. The band gap values of two functional inorganic/organic perovskites, K2SeBr6 and K2SeCl6, are strikingly close to 2.0 eV and 1.689 eV. (Using modified Becke Johnson (mBJ) approximations). Because the maximum peaks occur in the visible and ultraviolet regions, they suggest potential solar cell applications for the materials. K2SeX6 (X=Br, Cl) has good values for electron production, great potential for applications in the optoelectronic sector. Additionally, it is a semiconductor by nature, according to the results of other optical characteristics such as absorption coefficients, electron energy loss, conductivity, and reflectivity. Because the maximum peaks occur in the visible and ultraviolet regions, they suggest potential solar cell applications for the solids. For K2SeX6 (X= Cl, Br), the computed Seebeck coefficient at 100 K, the S values attained 299.9 μV/K and 219 μV/K, respectively, are positive, demonstrating p-type conduction. Both K2SeBr6 and K2SeCl6 have a figure of merit values that are more than one (ZT > 1) 300K range which indicates that they are effective thermoelectric materials, but after these values of temperature, the zTe values vary. The computations' findings are the foundation for K2SeX6 (X= Cl, Br) and are practically applicable to solar cells.

Microstructural Neurodegeneration of the Entorhinal-Hippocampus Pathway along the Alzheimer's Disease Continuum.

Conventional neuroimaging biomarkers for the neurodegeneration of Alzheimer's disease (AD) are not sensitive enough to detect neurodegenerative alterations during the preclinical stage of AD individuals. We examined whether neurodegeneration of the entorhinal-hippocampal pathway could be detected along the AD continuum using ultra-high-field diffusion tensor imaging and tractography for ex vivo brain tissues. Postmortem brain specimens from a cognitively unimpaired individual without AD pathological changes (non-AD), a cognitively unimpaired individual with AD pathological changes (preclinical AD), and a demented individual with AD pathological changes (AD dementia) were scanned with an 11.7T diffusion magnetic resonance imaging. Fractional anisotropy (FA) values of the entorhinal layer II and number of perforant path fibers counted by tractography were compared among the AD continuum. Following the imaging analyses, the status of myelinated fibers and neuronal cells were verified by subsequent serial histological examinations. At 250μm (zipped to 125μm) isotropic resolution, the entorhinal layer II islands and the perforant path fibers could be identified in non-AD and preclinical AD, but not in AD dementia, followed by histological verification. The FA value of the entorhinal layer II was the highest among the entorhinal laminae in non-AD and preclinical AD, whereas the FA values in the entorhinal laminae were homogeneously low in AD dementia. The FA values and number of perforant path fibers decreased along the AD continuum (non-AD>preclinical AD > AD dementia). We successfully detected neurodegenerative alterations of the entorhinal-hippocampal pathway at the preclinical stage of the AD continuum.

Analytical model of mechanical properties for a hierarchical lattice structure based on hierarchical body-centered cubic unit cell

Hierarchical structure features complex geometric topology and excellent mechanical properties. In this work, analytical models are developed to predict the mechanical properties as Young's modulus, Poisson's ratio, and yield stress of a lattice structure composed of hierarchical body-centered cubic. Analytical results were validated by finite element simulations. The compressed experiments of lattice samples fabricated by powder bed fusion were conducted to examine mechanical properties. The analytical model agrees well with the simulation results and experimental results. The largest discrepancy from the analytical model to the finite element simulations for Young's modulus of lattice structures is 7.5%. Regarding Poisson's ratio and yield stress, the largest discrepancy are 0.05% and 13.1%, respectively. Furthermore, the Young's modulus shows an increasing trend as the relative density of lattices increases and geometrical ratio λ decreases. Moreover, the influence of shear deformation on the mechanical properties of the lattice structures decreases with the gradual increase of geometrical ratio λ. The Young's modulus and yield stress for the lattices increase as geometrical ratio λ decreases with increasing relative density. The Poisson's ratio shows an opposite trend to the Young's modulus as well as the yield stress. Finally, the degree of anisotropy of Young's modulus for the lattice structure is investigated. The range of anisotropy values for the lattice structure is large, i.e., 2.98∼745. The anisotropy value of Young's modulus decreases with the relative density increasing. And, the anisotropy value of lattices decreases with increasing relative density, i.e., the monotonic trend. This work provides guidance for future designs of the hierarchical lattice structures from the aspects of theoretical prediction.

Archaeomagnetic analyses on fumiers burned under controlled experimental conditions

The improvement of the archaeomagnetic dating method requires compiling new and older data of the Earth's magnetic field (EMF) variations for the last millennia. Combustion events from fumier sequences have been proposed as good directional EMF recorders. However, they are subjected to diverse taphonomical processes and how these affect the archaeomagnetic record has not yet been studied. In order to evaluate it, here we report the first archaeomagnetic and rock-magnetic results on samples from experimentally recreated fumiers since 2014 under controlled conditions. A facies description with unprecedent resolution was used to study the variation of magnetic properties in depth. Rock-magnetic analyses indicate a homogenous magnetic mineralogy dominated by pseudo-single domain magnetite as main carrier in all facies, with not very high and similar contribution of the finest (superparamagnetic) grains. The low values of anisotropy of magnetic susceptibility (AMS) indicate that the studied sample set is mainly isotropic. The directional behaviour in well-preserved burned facies (here described as G, LM and DGB), are jointly characterized by highly reversible thermomagnetic curves, high Koenigberger (Qn) ratio values and intense, univectorial and normal polarity orthogonal NRM demagnetization diagrams. On the contrary, specimens affected by mechanical alteration processes are less magnetic and show anomalous directional behaviours. The high thermomagnetic reversibility of ashes indicates that they reached ca. 600–700 °C, in line with the thermocouples’ data. Temperatures of 460 °C were obtained for the DGB facies (subyacent black carbonaceous facies). Sampling of ashes located on the top of these combustion events should be avoided for archaeomagnetism. Being just beneath the last stabling episode they are the most prone to undergo mechanical alterations and do not preserve well the Earth's magnetic field direction. Despite their unlithified nature and the multiple taphonomic processes that fumier sequences may undergo, under certain quality criteria, they are valid geomagnetic field recorders providing both information of archaeological and geophysical interest.

Rapid neural changes during novel speech-sound learning: An fMRI and DTI study

While the functional and microstructural changes that occur when we learn new language skills are well documented, relatively little is known about the time course of these changes. Here a combined functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) study that tracks neural change over three days of learning Arabic phonetic categorization as a new language (L-training) is presented. Twenty adult native English-speaking (L-native) participants are scanned before and after training to perceive and produce L-training phonetic contrasts for one hour on three consecutive days. A third (Chinese) language is used as a control language (L-control). Behavioral results show significant performance improvement for L-training in both learnt tasks; the perception and production task. Imaging analysis reveals that, training-related hemodynamic fMRI signal and fractional anisotropy (FA) value increasing can be observed, in the left inferior frontal gyrus (LIFG) and positively correlated with behavioral improvement. Moreover, post training functional connectivity findings show a significant increasing between LIFG and left inferior parietal lobule for L-training. These results indicate that three hours of phonetic categorization learning causes functional and microstructural changes that are typically associated with much more long-term learning.

Modeling multiply scattered light in full-field optical coherence tomographic imaging of biological tissues

In this work, we have constructed a handheld full-field optical coherence tomography (FFOCT) system with high spatial resolution, and the Michelson interferometer (served as compensating optical path) and Fizeau interferometer (served as detection) were mounted in series in this system. The expressions of the multiple scattered light decomposed as the sum of incoherent and coherent contribution were derived based on the diffusion equation and mutual coherence function, and the variations of resolution with imaging depth were derived by using the model of multiple scattering. Experiments were conducted on samples composed of the USAF 1951 resolution target covered by the onion slice and human finger-skin slice, respectively, to validate and evaluate the accuracy of our model. A method of image restoration is then presented in which the relation between the resolution and measuring depth and the simulated PSF in the absence of multiple scattering are employed. With the help of this method the lateral resolution of 2.2 μm and 3.9 μm were separately achieved in the onion slice (measuring depth of 64 μm) and human finger-skin slice (measuring depth of 60 μm), and more tiny structures in the en face image of human finger-skin and moth wings were visible. In addition, a novel method for estimating the values of mean free path and anisotropy of scattering medium was proposed.

Effects of Damage to the Integrity of the Left Dual-Stream Frontotemporal Network Mediated by the Arcuate Fasciculus and Uncinate Fasciculus on Acute/Subacute Post-Stroke Aphasia.

(1) Background: To investigate the correlation between the integrity of the left dual-stream frontotemporal network mediated by the arcuate fasciculus (AF) and uncinate fasciculus (UF), and acute/subacute post-stroke aphasia (PSA). (2) Methods: Thirty-six patients were recruited and received both a language assessment and a diffusion tensor imaging (DTI) scan. Correlations between diffusion indices in the bilateral LSAF/UF and language performance assessment were analyzed with correlation analyses. Multiple linear regression analysis was also implemented to investigate the effects of the integrity of the left LSAF/UF on language performance. (3) Results: Correlation analyses showed that the diffusion indices, including mean fractional anisotropy (FA) values and the fiber number of the left LSAF rather than the left UF was significantly positively associated with language domain scores (p < 0.05). Multiple linear regression analysis revealed an independent and positive association between the mean FA value of the left LSAF and the percentage score of language subsets. In addition, no interaction effect of the integrity of the left LSAF and UF on language performance was found (p > 0.05). (4) Conclusions: The integrity of the left LSAF, but not the UF, might play important roles in supporting residual language ability in individuals with acute/subacute PSA; simultaneous disruption of the dual-stream frontotemporal network mediated by the left LSAF and UF would not result in more severe aphasia than damage to either pathway alone.

Differences in diffusion tensor imaging parameters of brain white matter tracts between patients with myotonic dystrophy type 1 and type 2 - a retrospective single-centre study.

The main aim of our study was to compare diffusion tensor imaging (DTI) parameters in patients with myotonic dystrophy types 1 and 2 (DM1 and DM2). To ascertain whether DTI could be used to assess the integrity of white matter tracts in the brain and identify any abnormalities or disruptions in connectivity between different brain regions in patients with DM. By providing a more detailed understanding of the structural changes in the brain associated with DM, could DTI potentially be used to develop more effective treatments for the cognitive and neurological symptoms of the disorder? We retrospectively compared MRI scans of 19 patients with DM1 to those of 23 healthy, matched controls, and of 16 patients with DM2 to those of 20 healthy, matched controls, and finally compared the DM1 and DM2 samples. Fraction anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) values were assessed using Tract Based Spatial Statistics (TBSS). In patients with DM1, a statistically significant decrease in the values of the FA parameter was revealed in 45/48 white matter tracts compared to patients with DM2. There was no statistically significant decrease in the values of the FA parameter in patients with DM2 compared to DM1. The values of MD and RD were significantly higher in 47 tracts in DM1 patients compared to DM2 patients. AD values were significantly higher in all 48 tracts in DM1 patients compared to DM2 patients. There were no tracts with increased MD, AD, or RD values in DM2 patients compared to DM1. Our results indicate diffuse disintegration of white matter pathways in DM patients, especially in the DM1 group. The damage to all types of fibres (association, commissural, and projection) may explain the diversity of clinical symptoms, which were more severe in the DM1 group of patients than in the DM2 group. DTI in patients with DM may help us to understand the neural mechanisms underlying brain involvement during the disease. In future, it may help to identify biomarkers for disease progression and treatment response.

Diffusion tensor imaging in trigeminal neuralgia: beyond the normal morphology

BackgroundTrigeminal neuralgia (TN) is an electric-like recurrent pain of a sudden onset and is localized to the area supplied by the trigeminal nerve, and the patients are usually free in between the attacks. It’s one of the most common causes of facial pain and is commonly induced by mechanical irritation, and there’s strong evidence suggesting an insult at the trigeminal nerve root which is usually caused by a neurovascular compression. The aim of the study was to evaluate the role of diffusion tensor imaging (DTI) in the detection of microstructural changes of normal appearing trigeminal nerve in patients with trigeminal neuralgia and the correlation between DTI parameters and pain severity.ResultsThirty one cases were included in the study (16 patients with TN and 15 healthy controls) underwent MRI with diffusion tensor imaging. The fractional anisotropy (FA) values of the trigeminal nerves were recorded and then comparison between the affected and unaffected sides in TN patients and healthy controls was done, also the degree of FA reduction was correlated with the pain severity in TN groups. The mean FA value of the affected trigeminal nerves was 0.43 ± 0.083, while that of the unaffected sides was 0.56 ± 0.058. The mean FA value of the trigeminal nerves in the healthy controls was 0.54 ± 0.057. A significant statistical differences was found between affected and unaffected sides (P < 0.00001) and between the affected sides and healthy controls (P < 0.0003), while no statistically significant difference was detected between the unaffected side and the healthy controls. A strong negative correlation was found between the pain score and the degree of FA reduction (P < 0.001).ConclusionsDiffusion tensor imaging is a functional MRI technique which can detect the microstructural changes in the normal appearing trigeminal nerves in patients with trigeminal neuralgia with a strong negative correlation between the severity of pain and the degree of FA reduction of the affected trigeminal nerve.

Differences and similarities in biophysical and biological characteristics between U87 MG glioblastoma and astrocyte cells.

Current cancer studies focus on molecular-targeting diagnostics and interactions with surroundings; however, there are still gaps in characterization based on topological differences and elemental composition. Glioblastoma (GBM cells; GBMCs) is an astrocytic aggressive brain tumor. At the molecular level, GBMCs and astrocytes may differ, and cell elemental/topological analysis is critical for identifying potential new cancer targets. Here, we used U87 MG cells for GBMCS. U87 MG cell lines, which are frequently used in glioblastoma research, are an important tool for studying the various features and underlying mechanisms of this aggressive brain tumor. For the first time, atomic force microscopy (AFM), scanning electron microscopy (SEM) accompanied by energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) are used to report the topology and chemistry of cancer (U87 MG) and healthy (SVG p12) cells. In addition, F-actin staining and cytoskeleton-based gene expression analyses were performed. The degree of gene expression for genes related to the cytoskeleton was similar; however, the intensity of F-actin, anisotropy values, and invasion-related genes were different. Morphologically, GBMCs were longer and narrower while astrocytes were shorter and more disseminated based on AFM. Furthermore, the roughness values of these cells differed slightly between the two call types. In contrast to the rougher astrocyte surfaces in the lamellipodial area, SEM-EDS analysis showed that elongated GBMCs displayed filopodial protrusions. Our investigation provides considerable further insight into rapid cancer cell characterization in terms of a combinatorial spectroscopic and microscopic approach.

Effect of variation of cold-rolling strain-paths on the microstructure, texture and mechanical properties of alloy Ni-16Cr-8Fe

In this work, the effect of variation of cold-rolling strain-paths (one-directional (U), two-stage cross (T), and multi-stage cross (M) rolling) on the evolution of microstructure as well as texture and their correlation with mechanical properties of alloy Ni-16Cr-8Fe has been studied. The overall texture strengthens while increasing rolling reductions from 30-to-50 and 50-to-90 % in all the strain-paths. In U strain-path, two of the standard rolling components—copper and brass—are strengthened significantly, while in T and M strain-paths only brass component strengthens. The overall texture has strong relationship with the brass-component of β-fibre irrespective of the strain-paths used during cold-rolling. The strain-path plays an important role in the changeover of texture from metal- to alloy-type, unlike what was previously thought that lowering of alloy’s stacking fault energy is the only reason. The yield (σYS) and tensile (σUTS) strength of 90 % rolled samples are significantly higher in U as compared to T and M strain-paths. The flow curves of 90 % rolled alloy follow Ludwigson-relationship with negative deviation in all the strain-paths. Regardless of the strain-paths, the area of yield locus ellipse increases as the rolling reductions are increased from 30-to-50 and 50-to-90 % and bear a good relationship with the overall texture. The average in-plane anisotropy in yield stress is observed to be highest in U strain-path. The theory of relative resolved shear stress of fcc slip systems in presence of highest intensity texture component well explains the variation in the values of in-plane anisotropies.

Noninvasive Prediction of Sperm Retrieval Using Diffusion Tensor Imaging in Patients with Nonobstructive Azoospermia.

Microdissection testicular sperm extraction (mTESE) is the first-line treatment plan for nonobstructive azoospermia (NOA). However, studies reported that the overall sperm retrieval rate (SRR) was 43% to 63% among men with NOA, implying that nearly half of the patients fail sperm retrieval. This study aimed to evaluate the diagnostic performance of parameters derived from diffusion tensor imaging (DTI) in predicting SRR in patients with NOA. Seventy patients diagnosed with NOA were enrolled and classified into two groups based on the outcome of sperm retrieval during mTESE: success (29 patients) and failure (41 patients). Scrotal magnetic resonance imaging was performed, and the DTI parameters, including mean diffusivity and fractional anisotropy, were analyzed between groups. The results showed that there was a significant difference in mean diffusivity values between the two groups, and the area under the curve for mean diffusivity was calculated as 0.865, with a sensitivity of 72.2% and a specificity of 97.5%. No statistically significant difference was observed in fractional anisotropy values and sex hormone levels between the two groups. This study demonstrated that the mean diffusivity value might serve as a useful noninvasive imaging marker for predicting the SRR of NOA patients undergoing mTESE.

Rapid and Accurate Prediction of the Axial Magnetic Anisotropy in Cobalt(II) Complexes Using a Machine-Learning Approach.

Estimating the magnetic anisotropy for single-ion magnets is complex due to its multireference nature. This study demonstrates that deep neural networks (DNNs) can provide accurate axial magnetic anisotropy (D) values, closely matching the complete-active-space self-consistent-field (CASSCF) quality using density functional theory (DFT) data. We curated an 86-parameter database (UFF1) with electronic data from over 33000 cobalt(II) compounds. The DNN achieved an R2 of 0.906 and a mean absolute error of 18.1 cm-1 in comparison to reference CASSCF D values. Remarkably, it is 11 times more accurate than DFT methods and 7700 times faster. This approach hints at DNNs predicting the anisotropy in larger molecules, even when trained on smaller ligands.

Structure and magnetic properties of hydrothermally synthesized CuFe2O4 and CuFe2O4/rGO composites

This paper presents a comparative analysis of the structural and magnetic modifications in ultrafine CuFe2O4 and CuFe2O4/rGO nanocomposites subjected to annealing. Samples were investigated using X-ray diffraction and Mössbauer spectroscopy. The study outlines the impacts of the annealing temperature on key characteristics, including the lattice parameter, inversion degree, and crystallite sizes. Copper ferrite nanoparticles demonstrate temperature stability as a composite element, displaying the simultaneous presence of both cubic and tetragonal ferrite phases at 500 and 600 °C. For heterogeneous copper ferrite, alterations in magnetocrystalline anisotropy values were calculated as a function of the inversion degree. The investigation also explores the influence of both crystallite size and inversion degree on the characteristic time of magnetic moment relaxation in a single domain CuFe2O4 nanoparticle, setting a precondition for the observation of superparamagnetic CuFe2O4 nanoparticles via the Mössbauer method. The study introduces a model for the inception of a copper ferrite phase predicated on the partial charge theory, offering an analysis of protolysis and polycondensation processes during the interaction of iron and copper hydroxocomplexes. The role of negatively charged graphene oxide nanosheets as ferrite phase nuclei localization centers is further substantiated within this context.

Dynamical electric characteristics of a quantum paramagnet

We consider the quantum paramagnet with the coupling between spin and electric degrees of freedom. The dynamical electric characteristics of the system under the action of the ac electric field are calculated. It is shown that for the closed system the quadrupole spin moment oscillates with the frequency of the ac field. The oscillations are modulated by the Rabi-like frequency, while the amplitude of the modulation is minimal at resonance, at which the frequency of the electric field is equal to the double energy of spin excitation of the paramagnet. The open system in the steady-state regime manifests only oscillations with the frequency of the ac field. The calculated dynamical electric susceptibility is nonzero only for nonzero dc magnetic field, and, depending on the values of the single-ion magnetic anisotropy, can manifest nonmonotonic dependence on temperature, dc electric and magnetic fields.

Integrity Assessment of High-Performance PVC Pipes for Thermal Wells.

In wells with high-viscosity crude oil, steam injection is used to improve the fluidity of the heavy oil. Screens made of steel are employed for sand control, with corrosion being a serious problem. Non-metallic pipe materials, such as novel high-strength PVC, are therefore being tried out. This paper presents the results of an integrity assessment of large-diameter hard PVC pipes under compressive loading. Plain, built-up, and slotted pipes were subjected to a 3-month aging process in saline water. Strain gauge sets were used for dynamic testing of longitudinal and transverse deformations. Values of fracture strength, total deformation, and anisotropy (Poisson's ratio) were extracted from the stress-strain graphs and analyzed. Upon aging in saline water, the stiffness of all pipes increased and was the highest for slotted pipes. Maximum stress after soaking was reduced by 11-12%. The ductility was the highest for plain pipes and the lowest for built-up pipes. Poisson's ratio remained almost constant for all pipes and aging conditions. The good news for field applications is that overall, aging had only a minor impact on the major compressive properties. The main conclusion was that corrosion-prone steel pipes and sand screens can be successfully replaced by corrosion-free high-strength PVC pipes and screens for water transport applications in thermal wells. This work provides a scientific basis for the structural integrity assessment of this new PVC and helps field engineers in the proper pre-deployment selection of pipes for target oilfields.

(Digital Presentation) Microstructure, Corrosion Resistance, and Magnetic Properties of Amorphous Alloy Co75Si15Fe5Cr4,5Al0,5 before and after Corrosion

Cobalt-based Amorphous Metal Alloys (AMA) can be used as soft magnetic materials in various magnetic devices due to the low value of the natural crystalline magnetic anisotropy. The addition of non-metallic components (Si, B) does not adversely affect the magnetic properties. On the contrary, AMA have high magnetic permeability at low values of coercive force and greater resistance to corrosion compared to crystalline ones.The required important parameters for corrosion description are: the concentration of chloride-ions, the microstructure (especially surface heterogeneity) and the composition of the oxide layer [1]. It was determined that the initial AMA Co75Si15Fe5Cr4.5Al0.5 possesses the low coercive force 0.38 A/m. The modification of the alloy surface with nanostructures by anodizing at different current densities (i) and times in the BmimBF4 ionic liquid (IL) does not affect the value of the coercive force, but its resistance to corrosion in a chloride solution increases. The coercive force increases after corrosion, which may be due to a change in surface morphology.The domain structures of the surface modified with nanostructures and initial alloys are different. After excerption at a constant (i) in IL, the domain structure of the surface consists of relatively large uniformly magnetized regions (Fig. 1a). The coercive force of the sample practically does not change compared to the initial sample.The surface domains after corrosion are broken into smaller ones, while the predominant orientation changes its direction (Fig.1 b). The change in the surface domain structure is accompanied by a significant increase in the coercive force (by a factor of 10), although the maximum magnetic permeability (the slope of the hysteresis loops) does not change.The EIS-tests (electrical impedance spectroscopy) were performed at -200 mV (Ag/AgCl) in the frequency range of 50,000 to 0.01 Hz and an oscillation amplitude of 20 mA in Ringer's solution (Fig.1 c, d) to compare the charge transfer kinetics for modified with nanostructures and initial samples. The simulated equivalent circuit included the values of the solution resistance Rs (22 Ω), the value of the constant phase element CPE associated with the double layer capacity, including the capacitance of the modified surface layer, and Rp is the charge transfer resistance across the interface. The capacity of the double layer is higher for the modified sample (4.28*10-5 Ohm-1*cN vs. 1.88*10-5 Ом-1*сN ) and the resistance value of the material has hardly changed (18000±13.5% Ohm for modified and 15500±3.5% Ohm for unmodified). The values of the phase angle (0.78 - modified and 0.88 - unmodified) indicate a greater heterogeneity of the charge distribution at the boundaries of the double layer for the modified surface of the alloy.So, surface modification affects the corrosion resistance, while it has little effect on the parameters of hysteresis loops, what is very important in practical applications. Nyby, C., Guo, X., Saal, J. E., Chien, S.-C., Gerard, A. Y., Ke, H., Frankel, G. S. (2021). Electrochemical metrics for corrosion resistant alloys. Scientific Data, 8(1).doi:10.1038/s41597-021-00840-y Figure 1

Altered corpus callosum structure in adolescents with cerebral palsy: connection to gait and balance.

Cerebral palsy (CP) is the most common motor disorder in childhood. Recent studies in children with CP have associated weakened sensorimotor performance with impairments in the major brain white-matter (WM) structure, corpus callosum (CC). However, the relationship between CC structure and lower extremity performance, specifically gait and balance, remains unknown. This study investigated the transcallosal WM structure and lower limb motor stability performance in adolescents aged 10-18 years with spastic hemiplegic (n = 18) or diplegic (n = 13) CP and in their age-matched controls (n = 34). The modern diffusion-weighted MRI analysis included the diffusivity properties of seven CC subparts and the transcallosal lower limb sensorimotor tract of the dominant hemisphere. Children with CP had comprehensive impairments in the cross-sectional area, fractional anisotropy, and mean diffusivity of the CC and sensorimotor tract. Additionally, the extent of WM alterations varied between hemiplegic and diplegic subgroups, which was seen especially in the fractional anisotropy values along the sensorimotor tract. The diffusion properties of transcallosal WM were further associated with static stability in all groups, and with dynamic stability in healthy controls. Our novel results clarify the mechanistic role of the corpus callosum in adolescents with and without CP offering valuable insight into the complex interplay between the brain's WM organization and motor performance. A better understanding of the brain basis of weakened stability performance could, in addition, improve the specificity of clinical diagnosis and targeted rehabilitation in CP.

Temperature dependent magnetic properties of crystallographically amorphous TbCo: An atomistic simulation study

Due to interesting properties such as perpendicular magnetic anisotropy (PMA), ferrimagnetism, etc., rare earth-transition metal(RE-TM) alloys attract considerable attention in ultrafast and terahertz spintronics applications. The magnetic properties of RE-TM alloys strongly depend on their composition and vary with temperature. Here, we model crystallographically amorphous ferrimagnetic TbCo using atomistic spin dynamics(ASD) simulations to study their temperature dependence on magnetic properties by varying the compositions. In this study, we investigate the temperature dependence of magnetisation, uniaxial anisotropy, and coercivity values of amorphous TbxCo100−x for the composition range Tb18Co82 to Tb36Co64. The monte carlo method is used to calculate the temperature dependence of magnetisation and calculate the magnetisation compensation temperature(TM) and curie temperature(Tc) values for different compositions. The temperature dependence of uniaxial anisotropy is calculated from the angular dependence of free energy curves calculated at different temperatures using constrained monte carlo methods. Further, we evaluate the temperature dependence of coercivity values by calculating the magnetic hysteresis at different temperatures using the LLG Heun method. The results show the magnetic properties of amorphous TbCo can be easily tuned by varying their composition and have a strong temperature dependence. These highly tunable magnetic properties make them promising candidates for spintronics applications.

Origin and effect of anisotropy in creep aging behavior of Al–Cu–Li alloy

The precise control of forming in the new generation Al–Li alloy is challenged by the anisotropic creep aging behaviors. This anisotropy is influenced by coupling effect the microstructure and process parameters during creep age forming, where process parameters such as creep aging temperature and stress play a crucial role. Taking the 2195 Al–Cu–Li alloy as an example material, the study aimed to investigate the effect of creep aging temperatures (140–200 °C) and stresses (150–200 MPa) on the anisotropic creep aging behaviors. The findings revealed that with increasing temperature and stress, the in planar anisotropy (IPA) value of creep deformation decreased from 19.1% to 9.4%, the IPA value of strength decreased from 10.3% to 5.1%. The study uncovered the anisotropy of creep aging and its mitigation mechanisms. The analysis revealed the crucial role of the initial texture and precipitation. By regulating the type and size of precipitates, the process parameters can mitigate anisotropic creep aging behavior. The stress-oriented precipitation of GPI (θ″) zones intensifies creep aging anisotropy, while the homogeneous precipitation of T1 phase hinders creep aging anisotropy, the smaller and more uniform the T1 phase, the stronger the hindering effect. The coarsened T1 phase have a relatively small effect on creep aging anisotropy. In conclusion, the optimal combination of low deformation anisotropy (9.4%) and excellent yield strength (527 MPa) can be achieved when the creep aging temperature is set at 170 °C under 200 MPa.