Biexciton lasing in CuCl quantum dots

Lasing of CuCl microcrystals embedded in a NaCl single crystal was observed for the first time. The lasing takes place at 77 K in a sample sandwiched between dielectric mirrors under pulsed ultraviolet laser excitation. The lasing transition is that from biexciton to exciton. The lasing is observed up to 108 K. The optical gain of the sample is almost the same as that of a CuCl bulk crystal in spite of the low concentration of CuCl in the NaCl matrix

肘の内外反変形に伴う尺骨神経の伸長度変化に関する生体力学的研究

Background: Cubital tunnel syndrome can be caused by overtraction and dynamic compression in elbow deformities. The extent to which elbow deformities contribute to ulnar nerve strain is unknown. Here, we investigated ulnar nerve strain caused by cubitus valgus/varus deformity using fresh-frozen cadavers. Methods: We used six fresh-frozen cadaver upper extremities. A strain gauge was placed on the ulnar nerve 2 cm proximal to the medial epicondyle of the humerus. For the elbow deformity model, osteotomy was performed at the distal humerus, and plate fixation was performed to create cubitus valgus/varus deformities (10°, 20°, and 30°). Ulnar nerve strain caused by elbow flexion (0–125°) was measured in both the normal and deformity models. The strains at different elbow flexion angles within each model were compared, and the strains at elbow extension and at maximum elbow flexion were compared between the normal model and each elbow deformity model. However, in the cubitus varus model, the ulnar nerve deflected more than the measurable range of the strain gauge; elbow flexion of 60° or more were considered effective values. Statistical analysis of the strain values was performed with Friedman test, followed by the Williams’ test (the Shirley‒Williams’ test for non-parametric analysis). Results: In all models, ulnar nerve strain increased significantly from elbow extension to maximal flexion (control: 13.2%; cubitus valgus 10°: 13.6%; cubitus valgus 20°: 13.5%; cubitus valgus 30°: 12.2%; cubitus varus 10°: 8.3%; cubitus varus 20°: 8.2%; cubitus varus 30°: 6.3%, P < 0.001). The control and cubitus valgus models had similar values, but the cubitus varus models revealed that this deformity caused ulnar nerve relaxation. Conclusions: Ulnar nerve strain significantly increased during elbow flexion. No significant increase in strain 2 cm proximal to the medial epicondyle was observed in the cubitus valgus model. Major changes may have been observed in the measurement behind the medial epicondyle. In the cubitus varus model, the ulnar nerve was relaxed during elbow extension, but this effect was reduced by elbow flexion.博士（医学）・甲第865号・令和5年3月15

Micro/Macro-Behavior of Water Flow and Diffusion in Clay : Multiscale Homogenization Analysis

Clay is a micro-inhomogeneous material. For bentonite clay we present here a unified numerical scheme to treat its molecular characteristics and micro/macro-continuum behavior. Note that we commonly use a macro-phenomenological model for analyzing material behavior. However, existing models are not sufficiently effective under extreme conditions such as deeply located clay. We try to resolve this difficulty. Properties of saturated bentonite are characterized by hydrated montmorillonite, the major clay mineral of bentonite. Since the crystalline structure of clay minerals determines fundamental properties, we analyze its molecular behavior by applying a molecular dynamics (MD) simulation and inquire into physicochemical properties of the clay hydrate system such as diffusivity of chemical species. To extend the microscopic characteristics of constituent materials to the macroscopic diffusion behavior of the micro-inhomogeneous material we develop a multiscale homogenization analysis (HA) to treat adsorption behavior at a micro-level

Physical Properties of Clay Minerals and Water : By means Molecular Dynamics Simulations

An interatomic potential model and a parameter set are presented for the molecular simulations of systems relating to clay. MD simulations of water and ice-Ih showed the validity of this model by reproducing structures and physical properties for the wide range of temperatures. The swelling properties of beidellite were simulated for various hydration numbers. The step-wise increase of basal spacing was shown with increasing hydration numbers, which are assigned to zero-, one-, two- and three-layer hydrations. The slope of internal energy of interlayer water for the increasing hydration number also shows step-wise behavior. MD simulations of clay molecule-water and aqueous solution systems were performed. Structural and physical properties of the interface were investigated as local properties. Electrical double layer and the diffusion layer were investigated for both systems

粘土中の水の流れと拡散に関するミクロ・マクロ解析 : 多段階均質化解析

Clay is a micro-inhomogeneous material. For bentonite clay we present here a unified numerical scheme to treat its molecular characteristics and micro/macro-continuum behavior. Note that we commonly use a macro-phenomenological model for analyzing material behavior. However, existing models are not sufficiently effective under extreme conditions such as deeply located clay. We try to resolve this difficulty. Properties of saturated bentonite are characterized by hydrated montmorillonite, the major clay mineral of bentonite. Since the crystalline structure of clay minerals determines fundamental properties, we analyze its molecular behavior by applying a molecular dynamics (MD) simulation and inquire into physicochemical properties of the clay hydrate system such as diffusivity of chemical species. To extend the microscopic characteristics of constituent materials to the macroscopic diffusion behavior of the micro-inhomogeneous material we develop a multiscale homogenization analysis (HA) to treat adsorption behavior at a micro-level

Reversible Regulation of Drug Release from Chiral Liquid Crystalline Polymer Micelles without Leakage

Liquid crystalline polymers (LCPs) exhibit abrupt changes in their organized structures and mobilities at phase transition temperatures, which is reminiscent of the unique structures and properties of biological membranes. Despite the numerous potential applications of LCPs, no study of their medical use has been reported. In this study, we synthesized amphiphilic LCPs with chiral mesogens by introducing hydrophilic oligo(ethylene glycol) (OEG), hydrophobic mesogens, and chiral mesogens into polysiloxane main chains. The resulting chiral LCP-g-OEG formed micelles with a highly ordered hydrophobic core and a hydrophilic OEG shell. While the release of a model drug from chiral LCP-g-OEG micelles was effectively suppressed at temperatures below the nematic–isotropic phase transition temperature (TNI), it was enhanced by an increase in the temperature above TNI. The reversible thermoresponsive ON–OFF regulation of drug release without leakage was achieved by using chiral LCP-g-OEG micelles. Interestingly, the chiral LCP-g-OEG micelles were preferentially internalized by cancer cells compared with normal cells

粘土鉱物と水の物性 : 分子動力学シミュレーションによる

An interatomic potential model and a parameter set are presented for the molecular simulations of systems relating to clay. MD simulations of water and ice-Ih showed the validity of this model by reproducing structures and physical properties for the wide range of temperatures. The swelling properties of beidellite were simulated for various hydration numbers. The step-wise increase of basal spacing was shown with increasing hydration numbers, which are assigned to zero-, one-, two- and three-layer hydrations. The slope of internal energy of interlayer water for the increasing hydration number also shows step-wise behavior. MD simulations of clay molecule-water and aqueous solution systems were performed. Structural and physical properties of the interface were investigated as local properties. Electrical double layer and the diffusion layer were investigated for both systems