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Objective: Radiofrequency ablation (RFA) is the preferred approach for selective reduction in complex monochorionic (MC) multiple pregnancies owing to the ease of operation and minimal invasiveness. To optimize the RFA technique and reduce the risk of adverse pregnancy outcome resulting from the heat‐sink effect of RFA therapy, we used an innovative RFA method, in which an electrode needle was expanded incrementally and stepwise. This study aimed to assess the efficacy and safety profile of this novel multistep incremental expansion RFA method for selective fetal reduction in MC twin and triplet pregnancies. Methods: This was a single‐center retrospective cohort study of all MC multiple pregnancies undergoing RFA between March 2016 and October 2022 at our center. The multistep RFA technique involved the use of an expandable needle, which was gradually expanded during the RFA procedure until cessation of umbilical cord blood flow was achieved. The needle used for the single‐step RFA method was fully extended from the start of treatment. Results: In total, 132 MC multiple pregnancies underwent selective reduction using RFA, including 50 cases undergoing multistep RFA and 82 cases undergoing single‐step RFA. The overall survival rates were not significantly different between the multistep and single‐step RFA groups (81.1% vs 72.3%; P = 0.234). Similarly, the rates of preterm prelabor rupture of the membranes within 2 weeks after RFA, procedure‐related complications, spontaneous preterm delivery and pathological findings on cranial ultrasound, as well as gestational age at delivery and birth weight, did not differ between the two groups. However, there was a trend towards a prolonged procedure‐to‐delivery interval following multistep RFA compared with single‐step RFA (median, 109 vs 99 days; P = 0.377). Moreover, the fetal loss rate within 2 weeks after RFA in the multistep RFA group was significantly lower than that in the single‐step RFA group (10.0% vs 24.4%; P = 0.041). The median ablation time was shorter (5.3 vs 7.8 min; P < 0.001) and the median ablation energy was lower (10.2 vs 18.0 kJ; P < 0.001) in multistep compared with single‐step RFA. There were no significant differences in neonatal outcomes following multistep vs single‐step RFA. Conclusions: Overall survival rates were similar between the two RFA methods. However, the multistep RFA technique was associated with a lower risk of fetal loss within 2 weeks after RFA. The multistep RFA technique required significantly less ablation energy and a shorter ablation time compared with single‐step RFA in selective fetal reduction of MC twin and triplet pregnancies. Additionally, there was a trend towards a prolonged procedure‐to‐delivery interval with the multistep RFA technique. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]

Abstract: Background: China has one of the largest populations with tuberculosis worldwide. Cutaneous tuberculosis (CTB) is a rare manifestation of mycobacterial infection. Although CTB is well described, it is important to periodically revisit the prevailing clinical and epidemiological features in most populated countries such as China, India, and Indonesia, where tuberculosis is still a major health problem. Objective: This retrospective study aimed to re‐evaluate the CTB cases in China in the past 50 years to obtain a comprehensive insight into this multiplex entity. Methods: Cases of diagnosed CTB with confirmed histology from four large medical centres in central China between 1957 and 2013 were collected and analysed, including demographic data, clinical manifestations and pathological findings. Results: Of the 1194 cases enrolled, there were 666 (55.78%) and 528 cases (44.22%) of true CTB and tuberculids, respectively. Erythema induratum of Bazin (EIB) was the most common CTB (35.8%), followed by lupus vulgaris (LV, 32.7%), tuberculosis verrucosa cutis (18.9%), papulonecrotic tuberculid (8.0%), scrofuloderma (2.8%), tuberculosis cutis ulcerosa (1.3%), penile tuberculids (0.4%), and lichen scrofulosorum (0.1%). EIB was the predominant tuberculid (80.87%), while LV the predominant true CTB (58.7%). The number of diagnosed CTB showed a decreasing trend in the 1960s and 1970s, then increased again, and peaked in the 1990s. Conclusions: Cutaneous tuberculosis is still a common problem in China. Chronologic changes in CTB cases reported in China over the past 50 years may reflect the prevalence transition of overall tuberculosis. CTB has diverse clinical presentations, and each subtype is characterized by specific gender predilection, duration, age, clinic and pathological findings. [ABSTRACT FROM AUTHOR]

A modified normalization method is presented for obtaining crack tip opening displacement (CTOD) resistance curves of single edge-notched tension specimens. For the applied load mode, the normalization method should be based on force-crack mouth opening displacement. A formula is proposed for CLL(i), the core parameter used in the normalization calculation. The modified method is validated using the unloading compliance method. The study of specimen geometry shows that side-groove depth and crack depth have significant impacts on the obtained CTOD resistance curves, and the shape of the crack front affects the determination accuracy of crack length. [ABSTRACT FROM AUTHOR]

A new lead-free perovskite solid solution (1-x)BaTiO3-xBi (Mg1/2Zr1/2)O3 with morphotropic phase boundary (MPB) has been developed, and its structural and dielectric properties have been investigated. Rietveld structural analysis of the X-ray diffraction data suggest a composition-dependent tetragonal (P4mm) to cubic (Pm3m) phase transition with an intermediate, phase coexistence region, demarcating the MPB. The compositions with x ≤ 0.05 are tetragonal in the P4mm space group and the compositions with x ≥ 0.25 are cubic in the space group. Coexistence of monoclinic phase (space group Cm) with tetragonal/cubic phase (space group P4mm/Pm3m) is observed in the MPB region for the compositions with 0.10 ≤ x ≤ 0.22. The temperature dependence of permittivity exhibits a nonrelaxor type diffuse phase transition for all the compositions across the MPB. [ABSTRACT FROM AUTHOR]

Presence of unwanted phase(s) such as yttrium iron perovskite (YIP) in yttrium iron garnet (YIG) ceramics has limited the utilization of YIG in the wireless communication domain. These unwanted phase(s) have been deemed responsible for the high dielectric losses, thus contributing to poor performance. This paper focuses on understanding the phenomenological phase transformation during the conventional solid state synthesis of YIG. This is done in order to monitor conditions which favor formation of unwanted phase(s), which shall later be reduced. The phase changes during YIG formation as a function of reaction times and temperatures were determined through XRD analysis. The amounts of YIG formed at various reaction times were fitted into various kinetic models in order to mathematically link what occurs experimentally to the available theoretical descriptions of reactions. It is found that the Ginstling-Brounstein-Habert (GBH) model exhibited good mathematical correlation to the formation of YIG. Meanwhile the activation energy ( Ea) indicated 490 kJ/mol is required for the formation of YIG. At the end, a reaction model and mechanism between Fe2O3 and Y2O3 were established and illustrated to underline the effect of diffusion controlled environment on the formation of phases in YIG ceramics. [ABSTRACT FROM AUTHOR]

Calcium silicate composite (CaO)x(SiO2)1-x has significant applications in the bioactive materials in medical treatment and cementitious materials in construction engineering. In this study, to unravel the role of calcium atoms on the silicate composite, the molecular dynamics (MD) technique was used to simulate the structures, dynamics, and mechanical properties of (CaO) x (SiO2)1-x systems, with x varying from 0 to 0.6. The Feuston--Garofalini model was employed to describe the interatomic interactions in the systems. Q species, the connectivity factor, shows that the increase in calcium content in the silicate composite can lead to the depolymerization of the silicate network. Due to the high diffusion rate, the presence of Ca atoms also weakens the stability of the chemical bonds in the system. With the increasing calcium content, the molecular structure of the silicate skeleton is transformed from an integrity network to separated short chains, which significantly decreases the stiffness and cohesive force of the calcium silicate composites. On the other hand, the uniaxial tension response of the calcium silicate composites suggests that at the postfailure stage, Ca atoms associate with the nonbridging oxygen atoms and the reconstructed Ca-O connection slows down the irreversible damage of the composite, hereby enhancing the plasticity. [ABSTRACT FROM AUTHOR]

Perovskite-structured lithium lanthanum titanate (LLT, La2/3- x Li3 x TiO3, 0 < x < 0.16) is a promising solid electrolyte with high lithium ion conductivity and a good model system to understand lithium ion diffusion behaviors in solids. Molecular dynamics (MD) and related atomistic computer simulations were used to study the diffusion behavior and diffusion mechanism as a function of composition in LLT solid-state electrolytes. The effect of defect concentration on the structure and lithium ion diffusion behaviors in LLT was systematically studied using MD simulations and molecular static calculations with the goal to obtain fundamental understanding of the diffusion mechanism of lithium ions in these materials. The simulation results show that there exists an optimal vacancy concentration at around x = 0.067 at which lithium ions have the highest diffusion coefficient and the lowest diffusion energy barrier. The lowest energy barrier from dynamics simulations was found to be around 0.22 eV, which compared favorably with 0.19 eV from static nudged elastic band calculations. It was also found that lithium ions diffuse through bottleneck structures made of oxygen ions, which expand in dimension by 8%-10% when lithium ions pass through. By designing perovskite structures with larger bottleneck sizes can be a means of further improving lithium ion conductivities in these materials. [ABSTRACT FROM AUTHOR]

Nanoporous silica systems with porosity between 30% and 70% were developed using two Molecular Dynamics (MD) simulation protocols to obtain structures with dissimilar pore morphologies. Short- and medium-range structural characteristics including bond angle distributions and pair distribution functions were analyzed and found to be consistent with experimental results. Surface area to volume ratio and pore microstructures were characterized and compared with experimental observations. Mechanical properties including elastic, shear, and bulk moduli of these nanoporous silica systems were calculated and their change as a function of porosity was compared with experimental data and theoretical models. It was found that the elastic modulus of porous silica with 50% porosity is 5-14 GPa which is consistent with experimental results. The elastic moduli-porosity relationship was fitted by exponential and power functions, and analysis of coefficients was performed to obtain microstructure characteristics of the simulated nanoporous silica structures. This works confirms that two distinct nanoporous silica microstructures are generated with MD simulations which result in variations in mechanical properties and highlight the importance of selecting a nanoporous silica simulation method which approximates experimental systems. [ABSTRACT FROM AUTHOR]

A theory-driven model is formulated for the low-temperature oxidation of uranium exposed to oxygen. The model is based on diffusion of oxygen ions through the oxide film driven by the electrostatic potential generated between the metal and adsorbed oxygen ions. The model fits published experimental data well for temperatures between 20°C and 200°C and for oxide film thicknesses less than 300 nm. The derived reaction rate coefficients for parabolic and inverse logarithmic growth regimes correspond well to the available published values and outperform the existing empirically derived forms. These reaction rate coefficients can be applied to the oxidation of any metal that is driven by the generated electrostatic potential. [ABSTRACT FROM AUTHOR]

In this article, we report the substrate effect on ferroelectric and magnetic properties of epitaxial BiFeO3-based thin films at room temperature. ( La, Mn) cosubstituted BiFeO3 ( BFOLM) thin films were deposited on differently lattice mismatched single-crystal substrates to manipulate the strain states in the as-deposited films. All the films with 30-nm thick CaRuO3 bottom electrodes exhibited highly epitaxial growth behavior with a slightly monoclinic distorted lattice structure while their strain states are drastically different as confirmed by X-ray reciprocal space mapping. These films possessed significantly different macroscopic ferroelectric properties with giant remanent polarization of 101 ± 2, 65 ± 2, and 48 ± 2 μC/cm2 for the films grown on SrTiO3, ( La, Sr)( Al, Ta) O3, and LaAlO3, respectively. It is found that the room-temperature magnetic properties are also in accordance with their strain state, having a reciprocal relationship with polarization. For example, the enhanced magnetization is associated with the suppressed polarization and vice versa. The stain tunability of multiferroic properties in BFOLM thin films are presumably ascribed to the polarization rotation and oxygen octahedral tilts. [ABSTRACT FROM AUTHOR]

This study aims to understand the viscosity variation of amorphous materials, and hence establish a theoretical model for reliable applications. The investigation was carried out by simplifying an amorphous system to a mixture of many subsystems which switch their energy states and relaxation processes stochastically. The response of the macroscopic system is then treated as an ensemble average of relaxations of individual subsystems. Our derivation illuminates the transition from exponential to nonexponential relaxation and that the sudden increase of fragility in the viscosity-temperature relation with reducing temperature could be attributed to the bifurcation from the harmonic mean of the subsystems towards the arithmetic mean. The successful application of our model to the amorphous selenium indicates that the model captures the fundamental mechanism of viscosity variation. [ABSTRACT FROM AUTHOR]

Formation of intrinsic point defect in yttrium aluminum garnet ( YAG) is comprehensively investigated using first-principles calculations. We showed that the defect formation energies of intrinsic point defects closely depend on the possible values of chemical potentials of Y, Al, and O. Both YAl16(a) anti-site defect, oxygen vacancy VO, and interstitial Oi might be the preferred defect species when chemical potentials of Y, Al, and O vary in different areas. The O-related defects are also important intrinsic point defects in YAG and deserve to be further examined. The oxygen self-diffusion are investigated and we found that energy barrier of oxygen diffusion is enhanced and decreased by neighboring YAl16(a) and AlY anti-site defects, respectively. The results are used to explain the mechanism of experimental observations that Al2 O3 excess speeds up oxygen diffusion and that Y2 O3 excess suppresses oxygen diffusion in YAG. [ABSTRACT FROM AUTHOR]

Magnetic excitation of the iron-based superconductor parent compound BaFe2As2 at finite temperature are addressed with a first-principles formulation of the Helmholtz energy, which can account for the finite temperature mixture of many magnetic configurations. We find that it is the spin exchange coupling in the interplane c direction that dictates the spin density wave ordering. We have also quantitatively predicted the pressure dependence of the spin density wave ordering temperature, the Schottky anomaly, and the temperature dependence of thermal populations of several low-energy spin configurations, all in agreement with available experimental data. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 [ABSTRACT FROM AUTHOR]

The phase stability, electronic structure, compressibility, optical and elastic properties of two polymorphs of Ti3SnC2 were investigated using first-principle calculation. α-Ti3SnC2 is confirmed to be the preferred equilibrium phase under high pressure and high temperature. The electronic structure calculations reveal that the Ti and C atoms form a strong Ti1-C-Ti2-C-Ti1 covalent bond chain while the bonding between Ti1 and Sn is relatively weak. In the low frequency range from radio waves to visible light, Ti3SnC2 behaves similarly with TiC. This material exhibits anisotropic compressibility under hydrostatic pressure: it is more compressible along the c-direction than along a-direction, related to the different bond stiffness and bond angle changes under high pressure. The second-order elastic coefficients were calculated. For the α-phase, the bulk, B, shear, G, and Young's moduli, E, are calculated to be 169.4, 124, and 197.4 GPa, respectively. The low G/ B ratio partially explains why Ti3SnC2 is relatively soft and damage tolerant. [ABSTRACT FROM AUTHOR]

In this paper, the control of chaotic oscillations is investigated. A nonlinear control methodology termed input-output linearization is utilized. Chaotic attitude motion of a spacecraft moving on an elliptic orbit in the gravitational field with both air drag and internal damping is treated as an example. [ABSTRACT FROM AUTHOR]

Discusses atomistic simulations with atomic potentials including anion polarizability for low-index surfaces with various terminations. Energy for the most stable surface; Ratio between the experimental values and relaxed surface energies; Surface relaxation findings.

Magnetic excitation of the iron-based superconductor parent compound BaFe2As2 at finite temperature are addressed with a first-principles formulation of the Helmholtz energy, which can account for the finite temperature mixture of many magnetic configurations. We find that it is the spin exchange coupling in the interplane c direction that dictates the spin density wave ordering. We have also quantitatively predicted the pressure dependence of the spin density wave ordering temperature, the Schottky anomaly, and the temperature dependence of thermal populations of several low-energy spin configurations, all in agreement with available experimental data. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 [ABSTRACT FROM AUTHOR]