Histopathological and Cytogenetic Analysis of Epidural Adipose Tissue in Symptomatic Lumbar Epidural Lipomatosis

Lumbar epidural lipomatosis (LEL) is characterized by the abnormal accumulation of unencapsulated adipose tissue in the spinal epidural space. Symptomatic LEL occurs in middle aged and elderly patients, and it is most often seen in males. The purpose of this study was to elucidate the histopathological and cytogenetic characteristics of the epidural lipomatosis in patients with symptomatic LEL. Six patients undergoing decompressive spinal surgery (mean age, 69.4 years) were enrolled between 2013 and 2017. Three cases were steroid-induced and 3 cases were diagnosed as idiopathic LEL. We compared the differences in histological morphology between the subcutaneous fat tissue and epidural fat tissue in each patient. We also analyzed the karyotype of resected epidural lipomatous tissue using the G-band method. The epidural adipocytes were histologically more irregular and smaller compared with the subcutaneous adipocytes in all cases. The mean size of subcutaneous adipocytes and epidural adipocytes was 5,485.6 ± 2,584.1 µm2 and 2,705.4 ± 1,069.1 µm2, respectively. In cytogenetic analysis of the epidural adipocytes, loss of the Y chromosome (LOY) was found in all 6 cases. The mechanisms related to the development of LEL are not well understood. In this study, the size of the lipid component of epidural adipocytes was significantly smaller than that of subcutaneous adipocytes in LEL. Cytogenetically, LOY was frequently recognized. Although this may be an effect rather than a cause, LOY may be related to morphologic changes in and proliferation of adipocytes in LEL. LOY might partially contribute to the pathological mechanism or expression of LEL.

Ab Initio Investigation of Helium Mobility in La2Zr2O7 Pyrochlore

The α-decay of incorporated actinides continuously produces helium, resulting in helium accumulation and causing security concerns for nuclear waste forms. The helium mobility is a key issue affecting the accumulation and kinetics of helium. The energy barriers and migration pathways of helium in a potential high-level nuclear waste forms, La2Zr2O7 pyrochlore, have been investigated in this work using the climbing image nudged elastic band method with density functional theory. The minimum energy pathway for helium to migrate in La2Zr2O7 is identified as via La–La interstitial sites with a barrier of 0.46 eV. This work may offer a theoretical foundation for further prospective studies of nuclear waste forms.

Phase Stability of the Tin Monochalcogenides SnS and SnSe: A Quasi-Harmonic Lattice-Dynamics Study

The tin monochalcogenides SnS and SnSe adopt four different crystal structures, <i>viz.</i> orthorhombic <i>Pnma</i> and <i>Cmcm</i> and cubic rocksalt and π-cubic (P2₁3) phases, each of which has optimal properties for a range of potential applications. This rich phase space makes it challenging to identify the conditions under which the different phases are obtained. We have performed first-principles quasi-harmonic lattice-dynamics calculations to assess the relative stabilities of the four phases of SnS and SnSe. We investigate dynamical stability through the presence or absence of imaginary modes in the phonon dispersion curves, and we compute Helmholtz and Gibbs free energies to evaluate the thermodynamic stability. We also consider applied pressures from 0-15 GPa to obtain temperature-pressure phase diagrams. Finally, the relationships between the different crystal phases are investigated by explicitly mapping the potential-energy surfaces along the imaginary phonon modes and by using the climbing-image nudged elastic-band method.

Mechanical Properties and Strength Grading of Engineered Bamboo Composites in China

Engineered bamboo composite (EBC) is a new high-strength anisotropic structural material, which has standardized sections and less inherent variability than the natural material. For safety reasons in structural applications, the characteristic values of mechanical behaviors are needed to build the design values utilized in practical application. Recent research studies on EBC focused on the mechanical properties from a single source, with little research on the sampling of the manufacturers. The present work investigates mechanical properties of two types of commercially available EBC—parallel strand bamboo (PSB) and laminated veneer bamboo (LVB). The main aim of this work is to evaluate the best probability distribution model (normal, lognormal, and Weibull) and mechanical properties for EBC in China and determine the characteristic values indicated by ASTM D2915. The mechanical properties in tensile, compression, and shear were evaluated using about 4300 small clear specimens from seven manufacturers in five raw bamboo origins of China. Based on the confidence band method, the strength grading of EBC subjected to compressive strength was developed with two predictors (density and MOE). By using intervals of each predictor, several strength grades were built. Each grade has the mean compressive strength, 5th percentile lower value (R0.05), and characteristic value (Rk), which could be used in structural design. This research contributes to the establishment of EBC standards and is essential for further accepting these materials in structural engineering.

Frequency Band and PCA Feature Comparison for EEG Signal Classification

The frequency band method is popular in signal processing; this method separates EEG signals into five bands of frequency. Besides the frequency band, the recent research show PCA method gives a good result to classify digits number from EEG signal. Even PCA give a good accuracy to classify digit number from EEG signal, but there are no research shows which one yielded better accuracy between PCA and frequency band to classify digit number from EEG signals. This paper presents the comparison between those methods using secondary data from MindBigData (MDB). The result shows that the frequency band and PCA achieve 9% and 12,5% on average accuracy with the EPOC dataset. The paired Wilcoxon test produces a significant difference in accuracy between methods in the digit classification problem. Experiment with Muse dataset provides 31% accuracy with frequency band method and 24,8% with PCA method. The result is competitive compared to other experiments to classify digit numbers from EEG signals. In conclusion, there is no winner between the two methods since no method fits both datasets used in this research.

Phase Stability of the Tin Monochalcogenides SnS and SnSe: A Quasi-Harmonic Lattice-Dynamics Study

The tin monochalcogenides SnS and SnSe adopt four different crystal structures, <i>viz.</i> orthorhombic <i>Pnma</i> and <i>Cmcm</i> and cubic rocksalt and π-cubic (P2₁3) phases, each of which has optimal properties for a range of potential applications. This rich phase space makes it challenging to identify the conditions under which the different phases are obtained. We have performed first-principles quasi-harmonic lattice-dynamics calculations to assess the relative stabilities of the four phases of SnS and SnSe. We investigate dynamical stability through the presence or absence of imaginary modes in the phonon dispersion curves, and we compute Helmholtz and Gibbs free energies to evaluate the thermodynamic stability. We also consider applied pressures from 0-15 GPa to obtain temperature-pressure phase diagrams. Finally, the relationships between the different crystal phases are investigated by explicitly mapping the potential-energy surfaces along the imaginary phonon modes and by using the climbing-image nudged elastic-band method.

Phase Stability of the Tin Monochalcogenides SnS and SnSe: A Quasi-Harmonic Lattice-Dynamics Study

The tin monochalcogenides SnS and SnSe adopt four different crystal structures, <i>viz.</i> orthorhombic <i>Pnma</i> and <i>Cmcm</i> and cubic rocksalt and π-cubic (P2₁3) phases, each of which has optimal properties for a range of potential applications. This rich phase space makes it challenging to identify the conditions under which the different phases are obtained. We have performed first-principles quasi-harmonic lattice-dynamics calculations to assess the relative stabilities of the four phases of SnS and SnSe. We investigate dynamical stability through the presence or absence of imaginary modes in the phonon dispersion curves, and we compute Helmholtz and Gibbs free energies to evaluate the thermodynamic stability. We also consider applied pressures from 0-15 GPa to obtain temperature-pressure phase diagrams. Finally, the relationships between the different crystal phases are investigated by explicitly mapping the potential-energy surfaces along the imaginary phonon modes and by using the climbing-image nudged elastic-band method.

Adsorption and Surface Diffusion of Metals on α-Al2O3 for Advanced Manufacturing Applications

The adsorption and diffusion of Mo and Nb adatoms on the $$\alpha$$ α -Al2O3 (0001) surface were explored using density functional theory-based methods. Adsorption energies of Mo and Nb adatoms at minima sites on the surface were determined. Mo and Nb adatoms prefer to adsorb to the same locations on the surface, and larger adsorption energies calculated for Nb compared to Mo indicate that Nb adatom-surface interactions are stronger than Mo. Using minima adsorption sites as initial and final locations for surface diffusion, energy barriers for diffusion were calculated using the nudged elastic band method. Overall, Mo and Nb follow roughly the same diffusion paths. The diffusion pre-factors for Mo and Nb are similar; however, Mo diffusion has a lower energy barrier and thus a larger diffusion coefficient compared with Nb. These results provide insight into the role of surface diffusion of Mo and Nb adatoms during advanced manufacturing processes.