Origin of the thermal plasticity property of zirconium oxide gels for use in direct thermal nanoimprinting

Some types of oxide gels derived from solutions exhibit a thermal plasticity property. In our previous report, the thermal plasticity property was utilized to produce oxide patterns and thin film transistors. However, it was not clear why some oxide gels exhibited a thermal plasticity property. In this report, we prepared not only a plastic ZrO₂ gel but also a non-plastic ZrO₂ gel, and investigated the structural and thermal properties of these gels to clarify why some gels exhibit a thermal plasticity property. We identified a clustered structure in ZrO₂ gels, with a Zr-O-Zr core coordinated by organic ligands. This structure was strongly related to the thermal plasticity property. The thermal plasticity property of ZrO₂ gel resulted from desorption and oxidization of the extra ligands by heating. We determined that the plastically deformed gels were consisted of clusters, and that the behaviour of ligands was a trigger in making a gel plastically deformed.     

Controllable Magnetic Proximity Effect and Charge Transfer in 2D Semiconductor and Double-Layered Perovskite Manganese Oxide van der Waals Heterostructure

Optically generated excitonic states (excitons and trions) in transition metal dichalcogenides are highly sensitive to the electronic and magnetic properties of the materials underneath. Modulation and control of the excitonic states in a novel van der Waals (vdW) heterostructure of monolayer MoSe₂ on double-layered perovskite Mn oxide ((La_0.8Nd_0.2)_1.2Sr_1.8Mn₂O₇) is demonstrated, wherein the Mn oxide transforms from a paramagnetic insulator to a ferromagnetic metal. A discontinuous change in the exciton photoluminescence intensity via dielectric screening is observed. Further, a relatively high trion intensity is discovered due to the charge transfer from metallic Mn oxide under the Curie temperature. Moreover, the vdW heterostructures with an ultrathin h-BN spacer layer demonstrate enhanced valley splitting and polarization of excitonic states due to the proximity effect of the ferromagnetic spins of Mn oxide. The controllable h-BN thickness in vdW heterostructures reveals a several-nanometer-long scale of charge transfer as well as a magnetic proximity effect. The vdW heterostructure allows modulation and control of the excitonic states via dielectric screening, charge carriers, and magnetic spins.     

Enhanced function of chondrocytes in a chitosan-based hydrogel to regenerate cartilage tissues by accelerating degradability of the hydrogel via a hydrolysable crosslinker

Chitosan-based hydrogels as scaffolds for culturing chondrocytes were prepared using linkers with and without hydrolysable poly(dl -lactide) (PLA) segments. The evaluation of the cultured chondrocytes in them indicated that the accelerated degradation of the hydrogel via hydrolysis of the PLA slightly promoted production of the sulfated glycosaminoglycan and drastically improved that of collagen from the encapsulated chondrocytes, which are the chondrospecific extracellular matrix components. Furthermore, the accelerated degradability significantly upregulated the gene expression for Collagen II production and downregulated that for Collagen I production of the encapsulated chondrocytes. Because major component of the articular cartilage tissue is Collagen II-rich hyaline cartilage, these results suggest the degradation of the scaffolds is an important parameter in cartilage tissue regeneration and the accelerated degradability may have benefits on promotion of cartilage tissue regeneration especially from the viewpoint of hyaline cartilage-like collagen production. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48893.     

Who is peer reviewed? Comparing publication patterns of peer-reviewed and non-peer-reviewed papers in Japanese political science

Scientometrics - Until recently, some fields of social sciences and humanities have developed without peer-review (PR) systems. Since the introduction of the PR system, non-peer-reviewed studies...     

Hollow cathode atomic source applicable to gas,liquid residue,and solid sample phases

ABSTRACT

We have developed a compact DC-glow discharge hollow cathode atomic source without requiring extensive chemical pretreatment. This system is intended for laser absorption spectroscopy to function as the source of neutral atoms. Our investigative focus is on elements found in nuclear power related environments, particularly in the context of Fukushima Daiichi decommissioning. The elements constituting the samples are identified through investigating the emission produced by the relaxation of the sample atoms after being sputtered by Ne and Ar discharge. The emission spectrum was observed in pure substances and also compounds related to materials such as stainless steel, control material, cladding material, seawater, and concrete, which are expected to constitute the majority of radioactive wastes. In particular, brass and salt, compounds consisting of two elements, were sputtered to produce single atoms of each element. With a copper pipe as an example, the emission efficiency was also investigated, through which the optimal experimental conditions for sputtering were identified. It was found that sputtering would be likely to cause a reduction in pressure, and that emission intensity is related to the electronic temperature during discharge. In addition, this system is not restricted by sample shape or electronic conductivity, with only minor pretreatment.     

Room temperature deposition of freestanding BaTiO3 films: temperature-induced irreversible structural and chemical relaxation

The room temperature aerosol deposition method is especially promising for the rapid deposition of ceramic thick films, making it interesting for functional components in energy, mobility, and telecommunications applications. Despite this, a number of challenges remain, such as an enhanced electrical conductivity and internal residual stresses in as-deposited films. In this work, a novel technique that integrates a sacrificial water-soluble buffer layer was used to fabricate freestanding ceramic thick films, which allows for direct observation of the film without influence of the substrate or prior thermal treatment. Here, the temperature-dependent chemical and structural relaxation phenomena in freestanding BaTiO₃ films were directly investigated by characterizing the thermal expansion properties and temperature-dependent crystal structure as a function of oxygen partial pressure, where a clear nonlinear, hysteretic contraction was observed during heating, which is understood to be influenced by lattice defects. As such, aliovalent doping and atmosphere-dependent annealing experiments were used to demonstrate the influence of local chemical redistribution and oxygen vacancies on the thermal expansion, leading to insight into the origin of the high room temperature conductivity of as-deposited films as well as greater insight into the influence of the induced chemical, structural, and microstructural changes in room temperature deposited functional ceramic thick films.

Graphical abstract

     

Kinetics of chlorination of uranium–antimony composite oxide for uranium removal from waste catalyst used for acrylonitrile synthesis

For uranium removal from waste catalyst used for acrylonitrile synthesis, kinetics of chlorination of uranium–antimony composite oxide was studied. During the chlorination treatment with hydrogen chloride gas at a partial pressure of 0.6–6.7 kPa and 873–1173 K, the uranium–antimony composite oxide, USb₃O_10, which was contained in the waste catalyst converted to another composite oxide, USbO₅, then changed to uranium oxide. Both reaction rates of the conversions, from USb₃O₁₀ to USbO₅ and from USbO₅ to U₃O₈, were described by a first order function of the fraction of USb₃O₁₀ and USbO₅, and their activation energies under the condition at 1.0 kPa hydrogen chloride gas were almost same values at (8.0 ± 0.4) × 10⁴ J mol^?1.     

Spin‐thermoelectric voltage in longitudinal SSE elements incorporating LPE YIG films and polycrystalline YIG slabs with an ultrathin Pt layer

A spin‐thermoelectric (STE) voltage is generated when a temperature gradient ?T is applied to an element having a thin Pt layer coated on a magnetic substance. In this study, yttrium iron garnet (YIG) ferrimagnetic films prepared by liquid phase epitaxy (LPE) were tested as magnetic insulators. In addition, polycrystalline YIG slabs were tested to compare the STE voltages of film and slab samples. In a Pt coating and YIG film bilayer structure made by an ultrathin Pt layer of 1‐4 nm thickness and an LPE film of approximately 10 µm thickness, a large STE voltage of 600 µV was observed at a probe distance of 5 mm with a temperature difference ?T of 30 K. On the other hand, the STE voltage of a Pt layer and YIG slab bilayer structure was 340 µV, which is roughly half of that of the Pt/YIG‐film element. The cause of the large voltage observed experimentally for the longitudinal spin Seebeck effect element incorporating an LPE YIG film was discussed mainly from the viewpoint of the Pt layer resistivity and the effects of YIG specimen surface conditions on crystallinity and the magnetization process.