Suppression of the Charge Density Wave State in Two-Dimensional 1T-TiSe2 by Atmospheric Oxidation

Two-dimensional (2D) metallic transition-metal dichalcogenides (TMDCs), such as 1T-TiSe₂, have recently emerged as unique platforms for exploring their exciting properties of superconductivity and the charge density wave (CDW). 2D 1T-TiSe₂ undergoes rapid oxidation under ambient conditions, significantly affecting its CDW phase-transition behavior. We comprehensively investigate the oxidation process of 2D TiSe₂ by tracking the evolution of the chemical composition and atomic structure with various microscopic and spectroscopic techniques and reveal its unique selenium-assisting oxidation mechanism. Our findings facilitate a better understanding of the chemistry of ultrathin TMDCs crystals, introduce an effective method to passivate their surfaces with capping layers, and thus open a way to further explore the functionality of these materials toward devices.     

Synthesis and characterization of ETS-10: supported hollow carbon nano-polyhedrons nanosorbent for adsorption of krypton at near ambient temperatures

Hollow carbon nano-polyhedrons (HCNPHs) supported on Engelhard Titanosilicate-10 (ETS-10) were synthesized by wet impregnation technique using tetrahydrofuran as a solvent. Synthesized HCNPHs/ETS-10 nanosorbent was characterized by X-ray diffraction, Raman spectra, N₂-adsorption–desorption isotherm, BET surface area, and scanning electron microscopy to confirm the morphology and uniformity of carbon particles ranging from 50 to 70 nm in diameter. Sorption characteristics of this nanosorbent for krypton at various carbon loadings were determined using a bench-scale column apparatus. The dynamic sorption capacity of HCNPHs/ETS-10 nanosorbent calculated from the breakthrough curve, 0.75 mmol/kg, which was ~15 % higher than for that of activated carbon. The effect of temperature on the adsorption capacity was studied between 263–293 K. Operational capacity of the nanosorbent was found to be 0.45 mmol/kg at 263 K. The experimental results indicate that 10 wt% HCNPHs/ETS-10 nanosorbent showed promising results for krypton adsorption, indicating its potential as an economical and active sorbent for krypton removal from the off-gas streams resulting from operations for recycle of used nuclear fuel.     

Control the self-assembly of fluorenone-based polycatenars by tuning chain length

Using Suzuki coupling reactions as key steps, a series of fluorenone-based polycatenars, consisting of a central 2,7-diphenyl-9-fluorenone core connected with the 3,4,5-trialkoxybenzoate unit via –COO- linkage at each side have been synthesized. Upon elongation of the terminal alkyl chain, these compounds self-assembled into mesophase sequence of Col_hex/p6mm - Cub_I/$\mathit{Pm}\overline{3}n$ in solid states as well as organogels with interesting morphologies varied from 3D helical fibers to spherical structures in solvents.     

Stable blow-up dynamics in the -critical and -supercritical generalized Hartree equation

We study stable blow-up dynamics in the generalized Hartree equation with radial symmetry, which is a Schrödinger-type equation with a nonlocal, convolution-type nonlinearity: First, we consider the -critical case in dimensions and obtain that a generic blow-up has a self-similar structure and exhibits not only the square root blowup rate , but also the log-log correction (via asymptotic analysis and functional fitting), thus, behaving similarly to the stable blow-up regime in the -critical nonlinear Schrödinger equation. In this setting, we also study blow-up profiles and show that generic blow-up solutions converge to the rescaled , a ground state solution of the elliptic equation . We also consider the -supercritical case in dimensions . We derive the profile equation for the self-similar blow-up and establish the existence and local uniqueness of its solutions. As in the NLS -supercritical regime, the profile equation exhibits branches of nonoscillating, polynomially decaying (multi-bump) solutions. A numerical scheme of putting constraints into solving the corresponding ordinary differential equation is applied during the process of finding the multi-bump solutions. Direct numerical simulation of solutions to the generalized Hartree equation by the dynamic rescaling method indicates that the is the profile for the stable blow-up. In this supercritical case, we obtain the blow-up rate without any correction. This blow-up happens at the focusing level , and thus, numerically observable (unlike the -critical case). In summary, we find that the results are similar to the behavior of stable self-similar blowup solutions in the corresponding settings for the nonlinear Schrödinger equation. Consequently, one may expect that the form of the nonlinearity in the Schrödinger-type equations is not essential in the stable formation of singularities.     

Development and validation of an LC/MS/MS method for simultaneous determination of shionone and epi‐friedelinol in rat plasma for pharmacokinetic study after oral administration of Aster tataricus extract

A rapid and sensitive liquid chromatography tandem mass spectrometry (LC/MS/MS) method was developed and validated using spinasterol as the internal standard (IS) for the simultaneous determination of shionone and epi‐friedelinol in rat plasma. Plasma samples were pretreated using liquid–liquid extraction with ethyl ether. Chromatographic separation was achieved on a C₁₈ column (100 × 2.1 mm, 5 μm) with an isocratic elution consisting of acetonitrile–0.1% formic acid water (75:25, v/v) at a flow rate of 0.30 mL/min. Detection was performed under the selected reaction monitoring scan using an electrospray ionization in the positive ion mode. The mass transitions were as follows: m/z 427.4 → 95.1 for shionone, m/z 411.4 → 205.2 for epi‐friedelinol and m/z 395.3 → 105.2 for IS. All calibration curves exhibited good linearity (r > 0.995) over the concentration range for both components. The intra‐ and inter‐day precisions at three QC and lower limit of quantitation levels were both <10.21% in terms of relative standard deviation, and the accuracy ranged from ?7.13 to 8.02% in terms of relative error. The extraction recoveries of the compounds ranged from 82.07 to 89.81%. The developed method was successfully applied to the pharmacokinetic study of shionone and epi‐friedelinol after oral administration of Aster tataricus extract to rats. Copyright © 2015 John Wiley & Sons, Ltd.     

Modeling and optimization of laser transmission joining process between PET and 316L stainless steel using response surface methodology

Laser joining parameters play a very significant role in determining the quality of laser transmission joining between PET films and 316L stainless steel plates. In the present work, Laser power, joining speed and stand-off-distance were considered as joining parameters. The parameters that influence the quality of laser transmission joining were optimized using response methodology for achieving good joint strength and minimal joint width. The central composite second-order Rotational Design (CCRD) has been utilized to plan the experiments and response surface methodology (RSM) is employed to develop mathematical relationships between joining parameters and desired responses. Based on the developed mathematical models, the interaction effects of the process parameters on laser transmission joining were investigated and optimum joining parameters were achieved. The experimental values nearly agree with the predicted values from mathematical models, indicates that the models can predict the responses adequately and optimize the key process parameters quickly.     

Surface effects on the polarization reversal of the ferroelectric liquid crystal 8SI*

Abstract

The activation field for the switching time (τ_1/2) in the truly ferroelectric liquid crystal 8SI* (CE8; ΔS-(+)-4-(2′-methylbutyl) phenyl-4′-n-octylbiphenyl-4 carboxylate) has been studied for various surface conditions of the transparent electrode (SnO₂), in order to understand the memory effect, the polarization reversal mechanism and its surface effect. We prepared five different surfaces, namely one coated with polyvinyl alcohol (PVA) and the other four by scratching N-times(N = 0, 10, 20 and 30) with a paste made of Cr₂O₃ powder (about 0·1 μm). The number and the area of scratches on the electrode surface obviously increase with N. The polarization reversal processes are influenced by this treatment. τ_1/2 decreases with increasing N, but no change is observed in the contrast of the light transmittance. Two different activation fields, E _a1, for the applied field E > E ₀ and E _a2 for E < E ₀ are observed, where E ₀ is a certain field depending on the sample. Here E _a1 is much larger than E _a2; typically E _a1, = 260 kV cm^?1 and E _a2 = 144 kV cm^?1 for N = 0. This means that nucleation for the higher field needs a large activation energy which therefore has strong barriers. In contrast with this, nucleation for the low field occurs easily. Changing a surface condition, E _a2 clearly decreases with increasing N although E _a1 is almost independent of the surface scratching. This may suggest that E _a1 corresponds to the activation field for the bulk pinning and nucleation, and E _a2 for the surface pinning. The PVA treatment gives an intermediate influence between N = 0 and 10.