Anisotropy Coefficient Research Articles

Loss of cervical sagittal alignment worsens the cervical spinal lesions in patients with Hirayama disease.

To quantify the cervical sagittal alignment in patients with Hirayama disease (HD) and to investigate the effect of loss of cervical sagittal alignment upon the cervical spinal lesions in HD. Cervical sagittal alignments were measured in 253 HD patients and 63 healthy subjects by C2-C7 Cobb and a modified method of Toyama et al. Motor unit number estimation (MUNE) was performed in bilateral abductor pollicis brevis (APB) in all HD patients, and 31 patients further underwent cervical diffusion tensor imaging (DTI). Compared with healthy subjects, HD patients showed lower C2-C7 Cobb (P < 0.05), and 83.4% patients showed loss of cervical lordosis (cervical straight or kyphosis), which was greater than healthy subjects (55.6%, P < 0.05). Compared with lordotic/straight group, patients with cervical kyphosis showed lower MUNE values and greater single motor unit potential (SMUP) in bilateral APB, and higher apparent dispersion coefficient (ADC) and lower fractional anisotropy were observed at C4/C5 level in the latter than the former (P < 0.05). C2-C7 Cobb was associated with both C4/C5 ADC and bilateral SMUP (P < 0.05). Most HD patients showed loss of cervical sagittal alignments, and both MUNE and DTI detections demonstrated a positive correlation between loss of cervical sagittal alignments and cervical spinal lesions in HD. These findings supported that loss of cervical sagittal alignments may worsen motor impairments in HD. Therefore, it is necessary for clinicians to be aware of restoring cervical sagittal alignments during HD treatment.

In-situ synchrotron x-ray diffraction and thermal expansion of TiB2 up to ∼3050 °C

There is an increasing interest in understanding the performance and properties of ultra-high temperature ceramics due to their high melting points (<3000 °C) that make them promising for extreme environment applications. In-situ high temperature X-ray diffraction experiments were performed on TiB2 beads up to ∼3050 °C. For these experiments, TiB2 powders were fabricated into spherical beads via gel casting methods and densified in a high temperature graphite furnace. These sample beads were then levitated in a conical nozzle levitator with reducing atmosphere (3% H2 -Ar) while being heated using a 400 W CO2 laser. During levitation a collimated synchrotron X-ray source was used to perform in-situ, temperature-dependent structural characterizations. The anisotropic coefficients of thermal expansion of TiB2 were characterized as a function of temperature up to ∼3050 °C. Elucidation of these properties are critical for the advancement of TiB2 ceramics and other transition metal di-borides for use in high temperature applications such as hypersonic platforms, nuclear reactors, and atmospheric re-entry.

Mechanical aspects of semi-circular sandstone fractured specimens with U-notch in the presence of various bedding angles

In tunnel and underground structures, the deformation and damage of layered rock masses often exhibit substantial anisotropy, where the fracture pattern of layered rock masses containing notched cracks directly influences the construction stability of the project. By this virtue, this paper presents a theoretical formulation of the fracture toughness of anisotropic rock materials containing U-notches on the basis of the constitutive model of transversely isotropic materials. The anisotropic influence coefficients are also appropriately incorporated into the formulas of the point stress (PS) and mean stress (MS) criteria to obtain their corresponding modified relations. The fracture toughness (KIC) of sandstones with bedding angles is evaluated by utilizing semi-circular bend (SCB) and U-notched semi-circular bend (USCB) specimens. The theoretically obtained results and experimentally observed data display that the fracture toughness of the specimens gradually decreases with increasing bedding angle, irrespective of the notch tip radius. Further, the results of the mean stress criterion are closer to the experimental data in comparison with those of the point stress criterion. Additionally, the fracture damage patterns pertinent to the SCB and USCB sandstone specimens with various bedding angles are displayed and discussed. The achieved results could provide a solid basis for better realizing the engineering deformations and failure analyses of layered sandstones.

Assessment of renal allograft rejection with diffusion tensor imaging.

To investigate the value of DTI in differentiation of renal allograft rejection from well-functioning stable allograft, using fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values. In this prospective study, 22 transplant recipients with well-functioning stable allograft (group A) and 20 patients with renal allograft rejection (group B + C) were recruited over a period of 19 months from January 2018 to July 2019. DTI-MRI was performed in all the patients, and FA and ADC values were measured in cortical and medullary regions of the transplanted kidney. On biopsy, graft rejection was classified as acute (group B) (n = 7) and chronic graft rejection (group C) (n = 13) based on the BANNF scoring system. Statistical analysis was performed using STATA v.14.0. Statistically significant difference between group A and group B + C was noted for cortical (p < 0.001), and medullary (p = 0.003) FA values, and cortical (p = 0.020), and medullary (p = 0.046) ADC values. Cortical(p < 0.001) and Medullary(p = 0.020) FA values showed statistically significant difference between group A and group C, and cortical FA value(p = 0.012) also showed statistically significant difference between group B and group C. AUC (to differentiate between renal allograft rejection and well-functioning stable allograft) for cortical, and medullary FA values and cortical and medullary ADC values were 0.853(p < 0.001), 0.757(p = 0.004), 0.709(p = 0.021) and 0.736(p = 0.009), respectively. DTI is a promising functional MRI technique for the non-invasive assessment of renal allograft function. Diffusion parameters, such as FA and ADC values, can be useful in the differentiation of renal allograft rejection from well-functioning stable allograft.

Stress-Invariants-Based Anisotropic Yield Functions and Its Application to Sheet Metal Plasticity

The yield criterion, or so-called yield function, plays an important role in the study of the plastic working of a sheet because it governs the plastic deformation properties of the sheet during the plastic-forming process. In this paper, we propose a novel anisotropic yield function useful for describing the plastic behavior of various anisotropic sheets. The proposed yield function includes the anisotropic version of the second stress invariant J2 and the third stress invariant J3. The proposed yield function can explain the anisotropic plastic behavior of various sheets by introducing the parameters α and β and also exhibits both symmetrical and asymmetrical yield surfaces. The parameters included in the proposed model were determined with an optimization algorithm from uniaxial and biaxial experimental data under a proportional loading path. In this study, the validity of the proposed anisotropic yield function was verified by comparing the yield surface shape, normalized uniaxial yield stress value, and Lankford anisotropic coefficient R-value derived from the experimental results. Applications of the proposed anisotropic yield functions to an aluminum sheet showed symmetrical yielding behavior and, to pure titanium sheets, showed asymmetric yielding behavior; thus, it was shown that the yield curve and yield behavior of various types of sheet materials can be predicted reasonably by using the proposed new yield anisotropic function.

Thermorefringent noise in crystalline optical materials

Crystalline materials are increasingly employed to construct precision optical instruments because of their reduced mechanical dissipation and consequent reduction of thermal Brownian noise. However, the anisotropy of the crystalline state implies a fundamental source of thermal noise; depolarization induced by thermal fluctuations of its birefringence. We establish the theory of this effect, which is a generalization of prior treatments of thermo-optic noises in amorphous materials. This theory---in conjunction with poorly understood anisotropic thermal stress coefficients of crystalline coatings---predict that thermo-refringent noise in crystalline mirror coatings may be lurking within an order of magnitude of Brownian noise (below 100 Hz). Thus, in order to appreciate the full promise of crystalline optical materials, a more precise understanding of their anisotropic material constants is necessary. Barring that, we elucidate measurement techniques that can affect partial coherent cancellation of thermorefringent noise. In passing, our general formalism also predicts the existence of thermal beam-pointing noise.

АНАЛІЗ МАГНІТНОЇ АНІЗОТРОПІЇ ЗРАЗКІВ ПОРІД ПОЛІГОНУ КРИВОРІЗЬКОЇ НАД ГЛИБОКОЇ СВЕРДЛОВИНИ

Understanding the reasons and principles of anisotropy of geological rocks opens the way to assess geodynamic processes in regions, enables to track changes of geological factors that form them, provides information about the structure and directions of the dynamics of geological rocks and etc. The aim of this study is the investigation of the nature of magnetic anisotropy of a collection of 26 samples that were taken from the well "Suputnyk-2" (490–2720 m) of the Kryvorizka extremely deep well. The samples consist of the following rocks: biotite schists, gneisses, ferruginous quartzites, muscovite quartzites, microcline-plagioclase granites. The authors used equipment of the KLY-2 series to measure the magnetic susceptibility of samples having the shape of cuberhombic decahedron. The authors have performed primary processing of measurement results and calculation of anisotropy parameters in the ANIZO10 program. The following parameters were determined as a result of the analysis: value of magnetic susceptibility (χ); statistical value of the standard deviation; normal values of magnetic susceptibility along three axes; coefficients characterizing magnetic anisotropy (H1 – H6); magnetic inclination angle (D) and magnetic inclination angle (I). The authors performed an initial classification of rocks based on the practical data processing scheme. Analyzing the calculations based on the ellipsoid of magnetic susceptibility, four rock classes were obtained: the shape of a sphere (12 %), a flattened shape (46 %), triaxial (23 %) and a complex ellipsoid shape (19 %). This indicates the complex geological conditions where rocks from the well "Suputnyk-2" (490–2720 m) were formed. It is confirmed that the samples belong to the VІІ–X tectonofacies according to the authors' previous research. The authors have investigated the coefficient of differential magnetic anisotropy, such as acoustic anisotropy. According to the results of the calculations, it was established that samples with low magnetic anisotropy are only 3.8 % of the total number of samples. Highly anisotropic samples of the collection comprise 53.8 % of the total number. It indicates the variety of processes that affected the rocks during their formation. According to the previous research of the authors, the coefficient of acoustic anisotropy of the well samples also varies from 2.8 to 24.9 %. The symmetry of the acoustic tensor in the majority of rock textures is rhombic. The final step in comparing the research results of the parameters of acoustic and magnetic anisotropy involved a tectonofacial analysis of the obtained data. It was determined that both magnetic and acoustic anisotropy coefficients, calculated from their respective tensors, reflect changes in tectonofacial conditions during the formation of the studied rocks.

Analysis of Anisotropic Steady and Dynamic Seepage of Subsea Tunnels

Although the underwater tunnel is under a rapid development nowadays, the theoretical research methods, including reflection and angle transformation, are still in their infancy. At present, almost all the studies are based on the hypothesis that soil layers are homogeneous, but most of the soil layers are anisotropic in actual soil engineering. Therefore, an analytical derivation method of flow field in heterogeneous media based on the traditional equiangular transformation method is presented. Numerical simulation shows that with the increase of the anisotropic permeability coefficient ratio, the contour line of approximate ellipse becomes flat. On the contrary, the lateral permeability is proportional to the upgrade of the anisotropic permeability coefficient ratio and the permeability appears the same trend.

THE EFFECT OF FIBER ORIENTATION AND MULTIPLE PAPERMAKING ON RECONSTRUCTION AND INTERNAL MASS TRANSPORT OF A CARBON PAPER

Carbon paper is often used as the current collector and gas diffusion layer in lithium-air batteries and fuel cells, and its internal morphology greatly influences the diffusion of materials. Relevant literature shows that carbon paper is an anisotropic porous medium, and the distribution of carbon fiberrs has a regular pattern. The difference in fiber distribution angle leads to a difference in internal morphology, which affects the transport properties and anisotropy of carbon paper. In this paper, a numerical method that considers fiber placement angle range for reconstructing carbon paper is proposed, and some geometric models of carbon paper are reconstructed. The pore size distribution and transport properties of geometric model are calculated and studied by improved thirteen direction average method and lattice Boltzmann method. The effects of carbon fiber distribution angle and multiple papermaking on the transport properties and anisotropy coefficient of carbon paper are studied. Results with an increase in d&amp;#966; include an increase in the average effective diffusion coefficient in through-plane direction and a decrease in the anisotropy coefficient and average effective diffusion coefficient in in-plane direction. Double papermaking can improve the average anisotropy coefficient of carbon paper and the average effective diffusion coefficient in in-plane direction and reduce the average effective diffusion coefficient in through-plane direction. However, the influence of papermaking times (layer number &amp;#62; 1) on transport properties of carbon paper is insignificant.

Study of the anisotropy of frozen rocks at the Khanovei test site (Komi Republic) based on the data of controlled source radio-magnetotelluric soundings and electrical resistivity tomography

The results of a joint inversion of the data of controlled source radio-magnetotelluric soundings (CSRMT) and electrical resistivity tomography (ERT), obtained at the Khanovei permafrost test site near Vorkuta, are presented. The geological section in the work area is composed of Quaternary fluvio-glacial, lacustrine-glacial and alluvial deposits up to 60 m thick, overlying a sequence of sandstones, siltstones and mudstones of Permian age. The CSRMT survey was carried out using a grounded electrical line 480 m long as a source in the frequency range 1-1000 kHz. The results of various inversion options were compared: 1) isotropic one-dimensional (1D) inversion of CSRMT data; 2) isotropic separate two-dimensional (2D) inversion of CSRMT and ERT data; 3) joint anisotropic 1D inversion of CSRMT and ERT data. Based on the results of a joint anisotropic inversion of CSRMT data in the far and intermediate zones of the source and ERT data, a vertical anisotropy associated with horizontal layering of frozen Quaternary clay deposits in the depth range from 2 to 15-20 m was revealed and its parameters (horizontal and vertical resistivity and anisotropy coefficient) were determined. On the geoelectric section obtained from the ERT data, the thickness of the anisotropic layer of frozen clayey deposits is significantly overestimated. The middle part of the section, in the depth range from 15-20 to 60-70 m, is characterized by relatively low resistivity values (tens of ohmmeters). This is consistent with the results of previous studies, which established that the upper part of the Permian sediments is in a thawed state and is fractured and water-saturated. A high-resistivity layer (hundreds of ohmmeters) was revealed at the base of the geoelecric section according to CSRMT data. A significant increase in the resistivity of Permian rocks with depth is confirmed by the data of vertical electrical soundings previously performed in the Khanovey area.

Diffusion Tensor Imaging Parameters in Patients with Meningitis: A Case-control Study

Introduction: Neuroimaging plays an important role in the assessment of meningitis, but conventional Magnetic Resonance Imaging (MRI) is insensitive for early and specific diagnosis. Diffusion Tensor Imaging (DTI) can illustrate disturbances in white matter integrity before they become obvious on conventional MRI. Aim: To determine DTI parameters, specifically Fractional Anisotropy (FA) and Apparent Diffusion Coefficient (ADC), in patients with meningitis and compare them with controls. Materials and Methods: This case-control study was conducted over a period of 18 months at Teerthanker Mahaveer Medical College and Research Centre in Moradabad, Uttar Pradesh, India. The study included a total of 61 clinically diagnosed meningitis patients, aged 18 years and above, who were referred to the Department of Radiodiagnosis for an MRI Brain. Additionally, 61 controls were included. Conventional MRI images were obtained followed by DTI. FA and ADC values were calculated by placing Regions Of Interest (ROI) at different levels for both groups. DTI parameters for different causative organisms (bacterial, viral, tubercular, and fungal) were compared. Data was analysed using Statistical Package for the Social Sciences (SPSS) software version 24.0, and Analysis of Variance (ANOVA) test was used to identify significant differences. The p-value &lt;0.05 was considered as statistically significant. Results: FA values were significantly lower in cases compared to controls at all levels in the brain (mean whole brain FA value of 0.30±0.036 in cases vs 0.43±0.030 in controls). ADC values were significantly higher in cases at the cerebellum, brainstem, and whole brain levels compared to controls (mean whole brain ADC value of 0.812±0.095 in cases vs 0.758±0.026 in controls) (p-value&lt;0.05 considered statistically significant). These differences were evident in patients with clinically proven meningitis who had a normal appearance on conventional MRI, demonstrating the superiority of DTI over conventional MRI for the diagnosis of meningitis. Statistically significant differences were also found among different aetiological agents, highlighting the potential utility of DTI in the differential diagnosis of meningitis cases (mean whole brain FA of 0.31±0.038 in bacterial cases, 0.029±0.037 in viral cases, 0.299±0.034 in tubercular cases, and 0.27±0.00 in fungal cases vs. 0.43±0.030 in controls (p-value &lt;0.01) and mean whole brain ADC values of 0.80±0.051 in bacterial, 0.85±0.14 in viral, 0.79±0.058 in tubercular, 1.03±0.00 in fungal cases vs. 0.758±0.026 in controls (p-value &lt;0.01)). Conclusion: DTI is more sensitive than conventional MRI and is a useful early indicator of inflammatory process in patients with meningitis.

Development of retinal structure in perinatally HIV-infected children and adolescents: A longitudinal and cross-sectional assessment.

In perinatally HIV-infected (PHIV) children, cross-sectional studies reported on subtle structural retinal differences and found associations between the retina and structural brain changes. Our objective is to investigate whether neuroretinal development in PHIV children is similar to the development in healthy matched controls and to explore associations with the brain structure. We measured RT using optical coherence tomography (OCT) on two occasions in 21 PHIV children or adolescents and 23 matched controls-all with good visual acuity-with a mean interval of 4.6 years (SD 0.3). We also included 22 participants (11 PHIV children and 11 controls) together with the follow-up group for a cross-sectional assessment using a different OCT device. Magnetic resonance imaging (MRI) was used to assess the white matter microstructure. We used linear (mixed) models to assess changes in RT and its determinants (over time), adjusting for age and sex. The development of the retina was similar between the PHIV adolescents and controls. In our cohort, we found that changes in the peripapillary RNFL was significantly associated with changes in WM microstructural makers: fractional anisotropy (coefficient = 0.030, p = 0.022) and radial diffusivity (coefficient = -0.568, p = 0.025). We found comparable RT between groups. A thinner pRNFL was associated with lower WM volume (coefficient = 0.117, p = 0.030). PHIV children or adolescents appear to have a similar development of the retinal structure. In our cohort, the associations between RT and MRI biomarkers underscore the relation between retina and brain.

Multisequence magnetic resonance neurography of brachial and lumbosacral plexus in chronic inflammatory demyelinating polyneuropathy: correlations with electrophysiological parameters and clinical features

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare and challenging demyelinating disorder. It is necessary to increase our understanding of potential connections between imaging, electromyography, and clinical characteristics. The aim of this study was to evaluate the relationships between multisequence magnetic resonance neurography (MRN) findings, electrophysiological parameters, and clinical characteristics in CIDP patients. A cross-sectional study. Overall, 51 CIDP patients underwent MRN of the brachial and lumbosacral plexus, and nerve conduction studies. The inflammatory Rasch-built overall disability scale (I-RODS) questionnaire, CIDP disease activity status (CADS) scale, and muscle strength scores were evaluated by two neurologists. Electrophysiological parameters, clinical information, and multiparameter-MRN were analyzed for correlations. Multiparameter-MRN includes diameter, nerve-to-muscle T2 signal intensity ratio (nT2), contrast-enhanced ratio (CR), fractional anisotropy (FA), and apparent diffusion coefficient (ADC) of bilateral plexus nerve roots. Electrophysiological parameters that were not elicited were significantly higher in the lower extremities than in the upper extremities, and those were higher in sensory nerve conduction than in motor. There were moderate correlations between motor nerve conduction velocity and distal motor latency in nerve diameter, nT2, FA, and ADC, respectively (|r|, 0.45-0.64, p < 0.05). The correlations between CR and sensory nerve conduction velocity and peak latency were moderate, and ADC had a positive correlation with compound motor action potential amplitude (|r|, 0.45-0.63). FA correlated negatively with the course (r = -0.62) and cerebrospinal fluid (CSF) protein (r = -0.41), whereas ADC had correlated positively with CSF protein (r = 0.34). Only CR had a moderately negative correlation with CADS (r's = -0.57). Muscle strength in all extremities was positively correlated with FA (r's range, 0.41-0.49). There was no significant correlation between I-RODS scores and multiparameter-MR. MRN-derived multiparameter [nerve size, nT2, and diffusion tensor imaging (DTI) parameters] could serve as quantitative biomarkers of myelin sheath integrity in CIDP. DTI parameters and CR correlated with clinical characteristics better than morphological parameters-MR for CIDP patients.

A Study of Diffusion Tensor Imaging in Central Post-Stroke Pain: Traveling Beyond the Pain Pathways.

Central post-stroke pain (CPSP), seen in the aftermath of a stroke, is an underdiagnosed entity but quite a disabling complication. All the postulated theories regarding the pathogenesis of CPSP point to its origin in the central pain pathways. However, this study attempts to demonstrate the role of other contributing areas in the generation of CPSP. In this single-center tertiary care hospital-based study, 24 patients with both ischemic and hemorrhagic strokes of variable durations were recruited, and Magnetic Resonance Imaging (MRI) imaging with diffusion tensor imaging (DTI) acquisition was done. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the spinothalamic tract (STT), corticospinal tract (CST), superior thalamic radiation (STR), basal ganglia (BG), and primary somatosensory cortex (SSC) were compared between normal and abnormal sides and also in extrathalamic lesions separately. Significant differences with lower FA were noted in STT, CST, STR, and SSC and higher ADC values in BG, STR, CST, and SSC on comparison between the normal and lesion sides. On individual sub-analysis, ischemic stroke had significant changes in the FA value of CST and the ADC value of STR and CST, while hemorrhagic stroke had significant changes in the FA and ADC values of STR and SSC, as well as the FA value of STT. In the analysis of the extrathalamic strokes, significance persisted in all the studied parameters except the BG. The CST abnormalities were evident even in patients with clinical motor improvement. On multivariate analysis, visual analogue scale score severity was correlated with thalamic lesions. Contrary to the belief that STT is solely responsible for CPSP, the role of CST, STR, BG, and SSC as contributing areas is evident from this study and may be more well established if studied in a larger population.

A complete pipeline for glioma grading using intelligible AI on multimodal MRI data

1) Objectives: Machine learning for binary glioma grading have been extensively used on anatomical MRI, especially using the BraTS dataset. The relevance of radiomic criteria based on multimodal imaging, including diffusion, perfusion and spectroscopy data is to be explored, as multimodal datasets are scarce, and there is no common benchmark for performance comparison. 2) Material and methods: Poitiers University Hospital provides 123 multimodal patient data. We computed 124 features and let a recursive feature elimination algorithm (RFE) yield a relevant, reduced subset of features. We trained a SVM classifier on this subset. We proposed a method to adapt the BraTS dataset to allow performance comparison with the literature. We got a performance reference point by training on anatomical data only, and showed improvements when multimodalities were added. We explored the feature relevance through the RFE subset. The RFE subset is not constant and induce variability in the performances. To smooth the variability, we applied the RFE algorithm 100 times and incremented the selected features, resulting in a global feature ranking. We also show the best classifier reached on these 100 trainings and its feature subset. 3) Results: The best classifier reached 86.5% accuracy, with a mean accuracy on 100 trainings of 78.6%. The rankings shows that anatomical and perfusion sequences are the most relevant for glioma grading, especially T1 post-gadolinium, cerebral blood volume and flow. Intensity and texture features are frequently selected, while anisotropic diffusion coefficient, time to peak and mean time transit mappings seem irrelevant. 4) Conclusion: Multimodal radiomics improve the classification and are consistent with the radiological analysis.

Frequency-domain probe beam deflection method for measurement of thermal conductivity of materials on micron length scale.

Time-domain thermoreflectance and frequency-domain thermoreflectance (FDTR) have been widely used for non-contact measurement of anisotropic thermal conductivity of materials with high spatial resolution. However, the requirement of a high thermoreflectance coefficient restricts the choice of metal coating and laser wavelength. The accuracy of the measurement is often limited by the high sensitivity to the radii of the laser beams. We describe an alternative frequency-domain pump-probe technique based on probe beam deflection. The beam deflection is primarily caused by thermoelastic deformation of the sample surface, with a magnitude determined by the thermal expansion coefficient of the bulk material to measure. We derive an analytical solution to the coupled elasticity and heat diffusion equations for periodic heating of a multilayer sample with anisotropic elastic constants, thermal conductivity, and thermal expansion coefficients. In most cases, a simplified model can reliably describe the frequency dependence of the beam deflection signal without knowledge of the elastic constants and thermal expansion coefficients of the material. The magnitude of the probe beam deflection signal is larger than the maximum magnitude achievable by thermoreflectance detection of surface temperatures if the thermal expansion coefficient is greater than 5 × 10-6K-1. The uncertainty propagated from laser beam radii is smaller than that in FDTR when using a large beam offset. We find a nearly perfect matching of the measured signal and model prediction, and measure thermal conductivities within 6% of accepted values for materials spanning the range of polymers to gold, 0.1-300 W/(m K).

The evaluation of anterior thalamic radiation with diffusion tensor imaging in children with neurofibromatosis type-1

To determine whether there is a difference in the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values of the anterior thalamic radiation (ATR), which are involved in the inhibitory control mechanism, in Neurofibromatosis type-1 (NF1) patients with or without Neurofibromatosis bright objects (NBOs), in comparison to the healthy control group. Thirty children diagnosed with NF1 and 17 age-matched children were included in the study. 30 children with NF1 had a mean age of 10.47±5.43, compared to 11.35±5.43 of the control group. NF1 patients were divided into two groups as those with and without NBOs. The comparison was made by measuring ADC and FA values of ATR in patients with NF1 and a healthy control group. There was a significant difference in terms of ADC and FA values of ATR between the patients with NF1 and the control group. While a significant decrease was seen in FA values of ATR, ADC values were increased. There was a significant difference in ATR ADC and FA values between NF1 patients with and without NBOs and the healthy control group. On the other hand, no major difference was displayed between NF1 patients with NBOs and without NBOs in terms of ATR ADC and FA values. The results of increased ADC and decreased FA values may denote the demyelination process in ATR. We speculate that the onset of microstructural damage in the ATR may result in executive function impairment, particularly in the inhibitory control mechanism.

Enhancement of magnetoelectric coupling and anisotropy by Galfenol/PZT/Galfenol magnetoelectric sandwich device

In this work, we reported the large magnetoelectric coupling coefficient and magnetoelectric coupling anisotropy in Galfenol/PZT/Galfenol 2-2 symmetric magnetoelectric sandwich devices. The directional solidification method was used to produce a Galfenol alloy with <001> orientation, which possesses a significant magnetostriction of 279 ppm and a piezomagnetic coefficient of 14.8 ppm/Oe. A magnetoelectric coupling laminate of Galfenol/PZT/Galfenol was also prepared. The magnetoelectric coupling coefficient can reach 55.0 V/cm Oe at the resonance frequency under a 0.35 Oe AC excitation magnetic field due to the significant magnetostriction and high piezomagnetic coefficient. Furthermore, there was excellent linearity and sensitivity between the magnetoelectric output voltage and the AC excitation magnetic field. Simultaneously, the device displayed in-plane magnetoelectric anisotropy and cosine variation as the magnetic field angle changed. At its resonance frequency, the device produced a maximum power of 1.4 mW. Finally, the device was shown to power 42 LEDs and a temperature/humidity sensor, demonstrating that the device withGalfenol/PZT/Galfenol sandwich structure has potential in magnetic field sensing and energy harvesting applications. • The device presented the in-plane anisotropy of ME coupling and cosine variation with the change of magnetic field angle. • The produced maximum power of the device was successfully demonstrated to power 42 LEDs and temperature/humidity sensors at its resonance frequency.

Effect of configurational entropy on phase formation, structure, and magnetic properties of deeply substituted strontium hexaferrites

Solid solutions based on SrFe 12 O 19 strontium hexaferrite with deep (up to at.67%) co-substitution of triply charged Fe 3+ iron cations by triply charged diamagnetic Al 3+ aluminum, Ga 3+ gallium, and In 3+ indium cations, as well as by paramagnetic Co 3+ cobalt and Cr 3+ chromium cations, were obtained by conventional ceramic technology. This type of substitution leads to the formation of high-entropy phases. The phase composition of the obtained samples was studied by powder X-ray diffraction. The configurational mixing entropy was calculated for all the obtained samples, and its influence on the processes of phase formation was studied. The unit cell parameters are calculated and their dependences on the 〈r B 〉 average ionic radius of the iron sub-lattice are plotted. The average grain size varied within 2–5 μm. The field and temperature properties of the magnetization of the obtained samples were studied. The M s saturation magnetization is determined using the Law of Approach to Saturation. The M r residual magnetization, SQR loop squareness and H c coercivity are also determined. Based on the obtained data, the k magnetic crystallographic anisotropy coefficient and the H a anisotropy field are calculated. All the obtained and calculated values are plotted depending on the 〈r B 〉 average ionic radius of the iron sub-lattice. All plotted dependencies are non-linear. The T mo magnetic ordering and T f freezing temperatures are obtained from the ZFC and FC magnetization data. The cluster nature of the magnetic behavior for all the samples is revealed. The average cluster diameter reaches ∼ 400 nm. The interpretation of the magnetic properties is made taking into account the effect of high configurational mixing entropy and magnetic dilution of the iron sub-lattice.

Tensile and torsion tests of cylindrical specimens of aluminum alloy ASP35 obtained by the SLM method

The article presents the methods and results of tension and torsion mechanical tests of specimens grown by selective laser melting method from ASP35 aluminum powder. In particular, during torsion tests a video system for analyzing strain fields on the surface of the sample Vic-3D was used. The dependences of elastic and plastic characteristics are shown depending on the orientation of the samples with respect to the direction of growth. The values of the anisotropy coefficient of mechanical properties in tension and torsion are compared. It is shown that under torsion the anisotropy coefficient of properties has larger values than under tension.