[en] This article describes the epitaxial growth of superlattice YbGaO₃(ZnO)₅ (YGZO) and InGaO₃(ZnO)₅ (IGZO) thin films, which feature nanoscale multilayered structures, on (111) plane yttria-stabilized zirconia (YSZ) substrates through a combination of sputtering and reactive solid phase epitaxy processes. Our fabrication process involved thin ZnO epilayers deposited through sputtering onto the YSZ substrates, and then YbGaO₃(ZnO)₅ or InGaO₃(ZnO)₅ thin films deposited at room temperature on ZnO epi-layers, followed by high-temperature annealing (1200 °C) of the bilayer structures. To suppress vaporization of ZnO from the films, high-temperature annealing was performed in a box made of ceramic ZnO. We used X-ray diffraction and transmission electron microscopy (TEM) to analyze the thin films annealed under various conditions. The microstructural evolution in the film formed during reactive solid phase epitaxy process was explored by TEM observations. Single-crystalline YGZO and IGZO thin films without varying composition could be synthesized through a suitable annealing process in the ceramic ZnO box. - Highlights: • RGaO₃(ZnO)₅ (R = Yb or In) films were grown on yttria-stabilized zirconia substrates. • The use of a ZnO box during annealing can compensate for the loss of zinc from films. • The microstructures of both epitaxial films were dominated by the horizontal defects. • Optical properties of both samples are also investigated by UV–vis spectroscopy. • Appropriate annealing conditions are critical to obtaining high-quality epitaxial films

[en] This article describes our investigation of the hydrothermal epitaxial growth of c-plane ZnO films on Al₂O₃ substrates presenting ZnAl₂O₄ buffer layers. We obtained (111) ZnAl₂O₄ epitaxial layers on a-plane Al₂O₃ substrates readily through solid phase epitaxy. Although the ZnAl₂O₄ buffer layers grew epitaxially with a (111) out-of-plane orientation and comprised two coexisting equivalent azimuthal variants with relative 180° in-plane rotation, the ZnO epitaxial films grown upon them exhibited a c-plane orientation with unitary in-plane epitaxial orientation of <11^¯00>_ZnO∥<11^¯0>_ZnAl2O4 on the two different ZnAl₂O₄ variants. Taking the coincidence of the site lattices between the (0001) plane of ZnO and the (111) plane of ZnAl₂O₄ into account, a reduction in lattice misfit was achieved through a 30° rotation between the lattices of the ZnO and the ZnAl₂O₄. We used X-ray diffraction and transmission electron microscopy to obtain detailed microstructural views of the hydrothermally grown ZnO epitaxial films on the ZnAl₂O₄ buffer layers. - Highlights: • The c-plane ZnO films were epitaxially grown on Al₂O₃ substrates presenting ZnAl₂O₄ buffer layers. • We obtained (111) ZnAl₂O₄ epitaxial layers on a-plane Al₂O₃ substrates through solid phase epitaxy. • The ZnAl₂O₄ layers comprised two equivalent azimuthal variants with relative 180° in-plane rotation. • The c-plane ZnO epitaxial films grown on ZnAl₂O₄ layers with an in-plane relationship of <11^¯00>_ZnO∥<11^¯0>_ZnAl2O4

[en] The technique of activators generated by electron transfer for atom transfer radical polymerization (AGET-ATRP) of acrylonitrile (AN) has been first attempted in emulsion using the procedure of “one-pot”, “two-step” with polyethylene glycol monooleyl ether (Brij 35) as surfactant, cupric chloride (CuCl₂) as catalyst, hexamethylenetetramine (HMTA) as ligand, carbon tetrachloride (CCl₄) as initiator and ascorbic acid (VC) as reducing agent. The polymerization proceeds in controlled/living manner as indicated by first-order kinetics of the polymerization rate with respect to the monomer concentration, linear increase of the molecular weight of polyacrylonitrile (PAN) with monomer conversion and narrow polydispersity. Monomer conversion increases initially with the increase of ligand HMTA and then decreases. The ratio of [AN1] to [AN2] at 1:3 not only gives better control on the molecular weight and the molecular weight distribution, but also provides a more rapid polymerization rate. The rate of polymerization shows a trend of increase along with CCl₄ content. The apparent activation energy of the polymerization is calculated to be 46.6 kJ/mol. Chain extension of PAN with AN was also carried out and the chain extended PAN with 20520 molecular weight and 1.36 polydispersity was successfully obtained. - Graphical abstract: Kinetic plot for AGET ATRP of AN in emulsion AGET-ATRP of AN has first investigated in emulsion with HMTA as ligand, CCl₄ as initiator and VC as reducing agent. The polymerizations have been successfully conducted in a controlled manner in the presence of air as evidenced by a linear first-order kinetic plot and linear increase of molecular weight with monomer conversion. Highlights: ► AGET-ATRP of AN is first investigated in emulsion. ► HMTA is used as ligand. ► Chain extension of PAN with AN verifies the living nature of the polymerization system.

[en] Yb-based catalyst was used for the first time for atom transfer radical polymerization using activators generated by electron transfer (AGET ATRP) of acrylonitrile (AN) with 2-bromopropionitrile (BPN) as initiator, 2, 2′-bipyridine (bipy) as ligand, and tisn(II) bis(2-ethylhexanoate) (Sn(EH)₂) as reducing agent in the presence of air. With respect to AGET ATRP of AN catalyzed by CuBr₂, an evident increase of polymer tacticity was observed for AGET ATRP of AN. The increase of syndiotacticity became more and more pronounced than the increase of isotacticity of polyacrylonitrile (PAN) along with YbBr₃ content. The block copolymer PAN-b-PMMA with molecular weight at 60,000 and polydispersity at 1.36 was successfully prepared. - Graphical abstract: Yb-based catalyst was used for the first time for AGET ATRP of AN with BPN as the initiator, bipy as the ligand, and Sn(EH)₂ as the reducing agent in the presence of air. With respect to AGET ATRP with CuBr₂ as catalyst, an obvious increase of polymer tacticity was observed for AGET ATRP of AN. The increase of syndiotacticity became more and more pronounced than the increase of isotacticity of polyacrylonitrile (PAN) along with YbBr₃ content. The block copolymer PAN-b-PMMA with molecular weight at 60000 and polydispersity at 1.36 was successfully prepared. Highlights: ► Yb-based catalyst was used for the first time for AGET ATRP of AN. ► The reaction simultaneously controls polydispersity and tacticity of PAN. ► Well-defined block copolymer PAN-b-PMMA was successfully prepared.

[en] Fast neutron multiplicity measurement technology is an important attribute authentication technology. Under the premise of studying the basic theory, the Monte Carlo (MC) method is used to simulate the system structure and detection process by using Geant4 simulation toolbox and MCNPX, and then the fast neutron multiplicity distribution is solved by Matlab, The fast neutron multiplicity simulation platform with automatic modeling, neutron transport, data visual analysis and simulation, and cloud platform management data is designed and developed. Using the platform to carry out simulation calculation and experimental research on fast neutron multiplicity, the obtained fast neutron multiplicity distribution is consistent with the theoretical results. The simulation platform itself realizes quality mutual inspection, and the deviation between the simulation result and the experimental result is less than ± 10%. The research results show that the fast neutron multiplicity simulation platform has strong applicability and reliability and can be applied to the simulation measurement of nuclear materials. (authors)

[en] Highlights: • NiFe₂O₄/EG composites are prepared by low-temperature combustion synthesis. • NiFe₂O₄/EG composites are uniform and have a good crystallinity. • The MMW attenuation performance was studied upon MMV radar measurement device. • NiFe₂O₄/EG composites exhibit better MMW attenuation properties than EG. • We report a simple synthesis route for the preparation of MMW attenuation composites. - Abstract: In this paper, NiFe₂O₄/expanded graphite (EG) composites are successfully prepared by low-temperature combustion synthesis method. The morphology, structure and millimeter wave (MMW) attenuation properties of the NiFe₂O₄/EG composites are investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and MMV radar measurement device. The effects of fuel and stoichiometric ratio on the composites are also investigated. The results show that NiFe₂O₄/EG composites are uniform and have a good crystallinity. The composites possess better MMW attenuation properties than EG. The 3 and 8 MMW attenuation performances of NiFe₂O₄/EG composites are 8.5 dB and 14.6 dB, respectively

[en] Contrary to the common thermodynamic systems, systems with long-range interaction may cause non-concavity of s(ε) curves. In this paper, we propose a long-range interacting Ising chain in a staggered magnetic field model which has a non-concave entropy part. In this model, the first phase transition is accompanied by the phenomenon of temperature jump in microcanonical ensemble when proper magnetic field intensity is met, while this jump cannot be observed in canonical ensemble, which shows the non-equivalence of different ensembles.To exhibit the cross-over process from microcanonical to canonical, the cross-over phase transition properties are exhibited recently by putting the chain in thermal contact with an adjustable two-level heat reservoir. In this paper, we introduce a different method by employing Gaussian ensemble to show the cross-over process reversely, i.e., from canonical to microcanonical ensembles. As shown in this paper, by adjusting the parameters of the supporting parabolas in the Gaussian ensemble, one can observe the caloric curve of the system in any Gaussian ensemble. (author)

[en] Highlights: • PMPSQ was promising adsorbent for the removal of Hg(II) and Mn(II). • The adsorption kinetics followed the pseudo-second-order model. • The adsorption isotherms can be described by the monolayer Langmuir model. • The adsorption was controlled by film diffusion and chemical ion-exchange mechanism. - Abstract: Thiol-functionalized polysilsesquioxane was synthesized and used for the adsorption of Hg(II) and Mn(II) from aqueous solution. Results showed that the optimal pH was about 6 and 5 for Hg(II) and Mn(II), respectively. Adsorption kinetics showed that the adsorption equilibriums were established within 100 min and followed pseudo-second-order model. Adsorption isotherms revealed that the adsorption capacities increased with the increasing of temperature. The adsorption was found to be well described by the monolayer Langmuir isotherm model and took place by chemical ion-exchange mechanism. The thermodynamic properties indicated the adsorption processes were spontaneous and endothermic nature. Selectively adsorption showed that PMPSQ can selectively adsorb Hg(II) from binary ion systems in the presence of the coexistent ions Mn(II), Cu(II), Pb(II), Co(II), and Ni(II). Based on the results, it is concluded that PMPSQ had comparable high adsorption efficiency and could be potentially used for the removal of Hg(II) and Mn(II) from aqueous solution

[en] Highlights: • Microwave assisted esterification of stearic acid with ethanol was catalyzed by D418. • D418 exhibited remarkable catalytic performance for ethyl stearate formation. • It proved possible to prepare biodiesel rapidly and with good conversions by microwave heating. • The relative catalytic kinetics study has been conducted and modeled. - Abstract: Biodiesel fuel is gaining significant attention in recent years because of its environmental benefits and the growing interest in finding new resources and alternatives for conventional fuels. Biodiesel production from waste cooking oil with high free fatty acids usually requires esterification step to produce fatty acid methyl/ethyl ester. In the present work, the heterogeneous catalyst aminophosphonic acid resin D418 has been successfully utilized in the energy-efficient microwave-assisted esterification reaction of fatty acid ethyl ester (FAEE) from free fatty acid (FFA) stearic acid with short-chain alcohol ethanol. Under the reaction conditions of 9 wt% D418 and 11: 1 M ratio of ethanol to stearic acid at 353 K and atmospheric pressure, more than 90% conversion of the esterification was achieved in 7 h by microwave heating, while it took about 12 h by conventional heating. Moreover, the kinetics of this esterification reaction has been studied, and the relevant values of activation energy and pre-exponential factor were obtained

[en] Highlights: • Silica gel supported salicylaldehyde modified PAMAM dendrimers were synthesized. • SiO₂-G0-SA∼SiO₂-G2.0-SA were promising adsorbents for the removal of Hg(II). • The pseudo-second-order model described adequately the adsorption kinetics data. • The film diffusion mechanism dominated the adsorption processes of Hg(II). • Langmuir model provide best correlation of the experimental data. - Abstract: A series of silica gel supported salicylaldehyde modified PAMAM dendrimers (SiO₂-G0-SA∼SiO₂-G2.0-SA) were synthesized and their structures were characterized by FTIR, XRD, SEM, TGA, and porous structure analysis. The feasibility of these adsorbents for the removal of Hg(II) from aqueous solution was first described and the adsorption mechanism was proposed. The adsorption was found to depend on solution pH, the generation number of salicylaldehyde modified PAMAM dendrimers, contact time, temperature, and initial concentration. Results showed that the optimal pH was about 6 and the adsorption capacity increased with the increasing of generation number. Density functional theory (DFT) method was used to investigate the coordination geometries and the chelating mechanism. Adsorption kinetics was found to follow the pseudo-second-order model with film diffusion process as rate controlling step. Adsorption isotherms revealed that adsorption capacities increased with the increasing of temperature. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models were employed to analyze the equilibrium data. The adsorption can be well described by Langmuir isotherm model and took place by chemical mechanism. The thermodynamics properties indicated the adsorption processes were spontaneous and endothermic nature. The maximum adsorption capacity of SiO₂-G0-SA, SiO₂-G1.0-SA, and SiO₂-G2.0-SA were 0.91, 1.52, and 1.81 mmol g⁻¹, respectively. The considerable higher adsorption capacity compared with other adsorbents indicates SiO₂-G0-SA∼SiO₂-G2.0-SA are favorable and useful for the uptake of Hg (II), and can be potentially used as promising adsorbents for the effective removal of Hg(II) from aqueous solution