Band offset at the heterojunction interfaces of CdS/ZnSnP₂, ZnS/ZnSnP₂, and In₂S₃/ZnSnP₂

Heterojunctions were formed between ZnSnP₂ and buffer materials, CdS, ZnS, and In₂S₃, using chemical bath deposition. The band offset was investigated by X-ray photoelectron spectroscopy based on Kraut method. The conduction band offset, ΔEC, between ZnSnP₂ and CdS was estimated to be -1.2 eV, which significantly limits the open circuit voltage, VOC. Conversely, ΔEC at the heterojunction between ZnSnP₂ and ZnS was +0.3 eV, which is within the optimal offset range. In the case of In₂S₃, ΔEC was a relatively small value, -0.2 eV, and In₂S₃ is potentially useful as a buffer layer in ZnSnP₂ solar cells. The J-V characteristics of heterojunction diodes with an Al/sulfides/ZnSnP₂ bulk/Mo structure also suggested that ZnS and In₂S₃ are promising candidates for buffer layers in ZnSnP₂ thin film solar cells, and the band alignment is a key factor for the higher efficiency of solar cells with heterojunctions

Heme oxygenase-1 induction in the brain during lipopolysaccharide-induced acute inflammation

Delirium occurs in 23% of sepsis patients, in which pro-inflammatory cytokines and nitric oxide are suggested to be involved. However, in animal experiments, even a subseptic dose of lipopolysaccharide (LPS) injection induces both pro-inflammatory cytokines and inducible nitric oxide synthase in the brain, suggesting that the brain oxidative reaction can be induced in the subseptic condition. Then, we evaluated the changes of heme oxygenase-1 (HO-1), a sensitive oxidative marker, as well as interleukin (IL)-1β, IL-6, and inductible nitric oxide synthase (iNOS) mRNA in the hypothalamus and hippocampus of rats using real-time PCR after peripheral injection of LPS (2.0 mg/kg). As a result, these four kinds of mRNAs were induced significantly in both areas after LPS injection. These results suggest that peripheral inflammation induces an oxidative reaction in the brain, even if the inflammation is not lethal. It is also considered that several pathways are involved in brain HO-1 induction

A Vaspin-HSPA1L complex protects proximal tubular cells from organelle stress in diabetic kidney disease

Proximal tubular cells (PTCs) are crucial for maintaining renal homeostasis, and tubular injuries contribute to progression of diabetic kidney disease (DKD). However, the roles of visceral adipose tissue-derived serine protease inhibitor (vaspin) in the development of DKD is not known. We found vaspin maintains PTCs through ameliorating ER stress, autophagy impairment, and lysosome dysfunction in DKD. Vaspin-/- obese mice showed enlarged and leaky lysosomes in PTCs associated with increased apoptosis, and these abnormalities were also observed in the patients with DKD. During internalization into PTCs, vaspin formed a complex with heat shock protein family A (Hsp70) member 1 like (HSPA1L) as well as 78kDa glucose-regulated protein (GRP78). Both vaspin-partners bind to clathrin heavy chain and involve in the endocytosis. Notably, albumin-overload enhanced extracellular release of HSPA1L and overexpression of HSPA1L dissolved organelle stresses, especially autophagy impairment. Thus, vapsin/HSPA1L-mediated pathways play critical roles in maintaining organellar function of PTCs in DKD

Deformity of the proximal end of the femur following open reduction for developmental dislocation of the hip

We studied deformity of the proximal end of the femur following open reduction using the wide exposure method for developmental dislocation of the hip. We reviewed radiographs of 22 children with unilateral dislocation of the hip who had undergone open reduction between one and three years of age. Ages at final examination ranged from 14 to 21 years. None of the patients in this study had undergone any additional surgery. Avascular necrosis of the femoral head was not observed in any patients. Radiographic measurements were observed when the children were 3, 6, 9, and 12 years old, and at the final examination. Coxa magna and valga were the factors associated with poor results. Coxa valga had occurred at 6 to 12 years of age, but rapidly improved thereafter. Throughout the course of treatment the epiphysis-femoral neck angle was within the normal range. The fusion of the epiphyseal growth plates on both sides occurred simultaneously. The coxa valga was due to valgus of the femoral neck, and not to valgus head tilt. These results suggest that, provided the mechanics of the joint have been properly corrected as in our operation, the biomechanics of the hip will improve until growth ceases, but that it may take more than ten years to attain normality.</p

The serum vaspin levels are reduced in Japanese chronic hemodialysis patients

Background: Visceral adipose tissue-derived serine proteinase inhibitor (vaspin) is an adipokine identified in genetically obese rats that correlates with insulin resistance and obesity in humans. Recently, we found that 7% of the Japanese population with the minor allele sequence (A) of rs77060950 exhibit higher levels of serum vaspin. We therefore evaluated the serum vaspin levels in Japanese chronic hemodialysis patients. Methods: Healthy Japanese control volunteers (control; n = 95, 49.9 +/- 6.91 years) and Japanese patients undergoing hemodialysis therapy (HD; n = 138, 51.4 +/- 10.5 years) were enrolled in this study, and serum samples were subjected to the human vaspin RIA system. Results: The measurement of the serum vaspin levels demonstrated that a fraction of control subjects (n = 5) and HD patients (n = 11) exhibited much higher levels (> 10 ng/ml; Vaspin(High) group), while the rest of the population exhibited lower levels (< 3 ng/ml; Vaspin(Low) group). By comparing the patients in the Vaspin(Low) group, the serum vaspin levels were found to be significantly higher in the control subjects (0.87 +/- 0.24 ng/ml) than in the HD patients (0.32 +/- 0.15 ng/ml) (p < 0.0001). In the stepwise regression analyses, the serum creatinine and triglyceride levels were found to be independently and significantly associated with the vaspin concentrations in all subjects. Conclusions: The creatinine levels are negatively correlated with the serum vaspin levels and were significantly reduced in the Japanese HD patients in the Vaspin(Low) group

Order-Disorder Phenomena and Their Effects on Bandgap in ZnSnP₂

A ternary compound semiconductor ZnSnP₂ has the order-disorder transition, where the ordered and disordered phases are chalcopyrite (I42d, a = 5.651 Å, c = 2a) and sphalerite (F43m, a = 5.651 Å), respectively. In this study, the quantitative relationship between bandgap and long-range order parameter η was investigated by analyzing ZnSnP₂ bulk crystals obtained by various cooling rates in crystal growth. The Chipman and Warren method was used to evaluate the long-range order parameters from X-ray difffaction profiles. The results showed that the long-range order parameter η decreases from 0.94 to 0.54 with the increase in cooling rates, and the bandgap gradually reduced from 1.60 to 1.37 eV, corresponding to the η value. It was also demonstrated that bandgap tuning of ZnSnP₂ was possible by controlling the long-range order parameter through annealing process. This study clarified the effects of the order-disorder phenomena on bandgap in a model material, ZnSnP₂, based on the evaluation of long-range order parameter, which is also a promising technique to tune the bandgap without composition control

Ⅱ-Ⅳ-Ⅴ2型化合物半導体ZnSnP2のバルク結晶および薄膜作製と太陽電池材料への応用

京都大学0048新制・課程博士博士(工学)甲第20334号工博第4271号新制||工||1662(附属図書館)京都大学大学院工学研究科材料工学専攻(主査)教授 安田 秀幸, 教授 酒井 明, 准教授 野瀬 嘉太郎学位規則第4条第1項該当Doctor of Philosophy (Engineering)Kyoto UniversityDGA

A pn-junction between chalcopyrite phosphide semiconductors for photovoltaic application

We report on the fabrication of a pn-junction between II-IV-V₂ type compounds with a chalcopyrite crystal structure such as CdSnP₂ and ZnSnP₂ for photovoltaic application. In the fabrication process, Cd–Sn precursor thin films were prepared on ZnSnP₂ bulk crystals grown by the flux method and the precursor thin films reacted with phosphorus gas to form CdSnP₂/ZnSnP₂ junction. STEM-EDX analysis and SAED patterns revealed that CdSnP₂ was epitaxially grown on ZnSnP₂ bulk crystals, indicating that the favourable junction was obtained in the view point of carrier transport. In addition, Zn was also detected in the region of the CdSnP₂ thin film due to the diffusion of Zn during phosphidation. This suggests the formation of solid solution (Cd, Zn)SnP₂ between ZnSnP₂ and CdSnP₂, leading to realization of a homojunction. In the J−V measurements of the n-(Cd, Zn)SnP₂/p-ZnSnP₂ junction, a rectifying behavior was observed. The results in this work are cornerstones for photovoltaic application using II-IV-V₂ type compound semiconductors including phosphides

Fabrication of CdSnP₂ Thin Films by Phosphidation for Photovoltaic Application

We report on the fabrication of CdSnP₂ thin films for photovoltaic applications. The phosphidation method, where a cosputtered Cd–Sn precursor thin film reacts with phosphorus gas, was utilized for the preparation of CdSnP₂ thin films. In order to establish the fabrication process, the temperature dependence on product phases was investigated, and CdSnP₂ thin films were obtained by the phosphidation at 350 °C for 30 min under the phosphorus vapor pressure of 10⁻² atm. CdSnP₂ thin films showed an n-type conduction. The resistivity, the carrier concentration and the mobility were evaluated to be 1.7–1.9 × 10² Ω cm, 2–7 × 10¹⁵ cm⁻³, and 4.7–17 cm² V⁻¹ s⁻¹, respectively. CdSnP₂ thin films with relatively flat and smooth surfaces were obtained, although it was reported that ZnSnP₂ with the same crystal structure grew as the protrusion shape by the VLS growth mode. In order to investigate these difference in growth mechanism between CdSnP₂ and ZnSnP₂, the reaction process in the Cd–Sn–P system was investigated and discussed on the basis of the chemical potential diagrams. As the results, it was understood that Cd, Sn, and P₄ directly reacted to form CdSnP₂, while ZnSnP₂ was formed via the reaction among Zn₃P₂, Sn, and P₄ after Zn reacts with P₄ to produce Zn₃P₂. Therefore, it is speculated that this simple reaction route results in the high growth speed, and a smooth flat morphology was obtained in the fabrication of CdSnP₂ thin films