Physical properties of transparent perovskite oxides (Ba,La)SnO3 with high electrical mobility at room temperature

Transparent electronic materials are increasingly in demand for a variety of optoelectronic applications. BaSnO3 is a semiconducting oxide with a large band gap of more than 3.1 eV. Recently, we discovered that La doped BaSnO3 exhibits unusually high electrical mobility of 320 cm^2(Vs)^-1 at room temperature and superior thermal stability at high temperatures [H. J. Kim et al. Appl. Phys. Express. 5, 061102 (2012)]. Following that work, we report various physical properties of (Ba,La)SnO3 single crystals and films including temperature-dependent transport and phonon properties, optical properties and first-principles calculations. We find that almost doping-independent mobility of 200-300 cm^2(Vs)^-1 is realized in the single crystals in a broad doping range from 1.0x10^19 to 4.0x10^20 cm^-3. Moreover, the conductivity of ~10^4 ohm^-1cm^-1 reached at the latter carrier density is comparable to the highest value. We attribute the high mobility to several physical properties of (Ba,La)SnO3: a small effective mass coming from the ideal Sn-O-Sn bonding, small disorder effects due to the doping away from the SnO2 conduction channel, and reduced carrier scattering due to the high dielectric constant. The observation of a reduced mobility of ~70 cm^2(Vs)^-1 in the film is mainly attributed to additional carrier-scatterings which are presumably created by the lattice mismatch between the substrate SrTiO3 and (Ba,La)SnO3. The main optical gap of (Ba,La)SnO3 single crystals remained at about 3.33 eV and the in-gap states only slightly increased, thus maintaining optical transparency in the visible region. Based on these, we suggest that the doped BaSnO3 system holds great potential for realizing all perovskite-based, transparent high-frequency high-power functional devices as well as highly mobile two-dimensional electron gas via interface control of heterostructured films.Comment: 31 pages, 7 figure

Molecular Weight Dependent Glucose Lowering Effect of Low Molecular Weight Chitosan Oligosaccharide (GO2KA1) on Postprandial Blood Glucose Level in SD Rats Model

Abstract This research investigated the effect of enzymatically digested low molecular weight (MW) chitosan oligosaccharide on type 2 diabetes prevention. Three different chitosan oligosaccharide samples with varying MW were evaluated in vitro for inhibition of rat small intestinal α-glucosidase and porcine pancreatic α-amylase (GO2KA1; \u3c1000 Da, GO2KA2; 1000–10,000 Da, GO2KA3; MW \u3e 10,000 Da). The in vitro results showed that all tested samples had similar rat α-glucosidase inhibitory and porcine α-amylase inhibitory activity. Based on these observations, we decided to further investigate the effect of all three samples at a dose of 0.1 g/kg, on reducing postprandial blood glucose levels in Sprague-Dawley (SD) rat model after sucrose loading test. In the animal trial, all tested samples had postprandial blood glucose reduction effect, when compared to control, however GO2KA1 supplementation had the strongest effect. The glucose peak (Cmax) for GO2KA1 and control was 152 mg/dL and 193 mg/dL, respectively. The area under the blood glucose-time curve (AUC) for GO2KA1 and control was 262 h mg/dL and 305 h mg/dL, respectively. Furthermore, the time of peak plasma concentration of blood glucose (Tmax) for GO2KA1 was significantly delayed (0.9 h) compared to control (0.5 h). These results suggest that GO2KA1 could have a beneficial effect for blood glucose management relevant to diabetes prevention in normal and pre-diabetic individuals. The suggested mechanism of action is via inhibition of the carbohydrate hydrolysis enzyme α-glucosidase and since GO2KA1 (MW \u3c 1000 Da) had higher in vivo effect, we hypothesize that it is more readily absorbed and might exert further biological effect once it is absorbed in the blood stream, relevant to blood glucose management

High Mobility in a Stable Transparent Perovskite Oxide

We discovered that La-doped BaSnO3 with the perovskite structure has an unprecedentedly high mobility at room temperature while retaining its optical transparency. In single crystals, the mobility reached 320 cm^2(Vs)^-1 at a doping level of 8x10^19 cm^-3, constituting the highest value among wide-band-gap semiconductors. In epitaxial films, the maximum mobility was 70 cm^2(Vs)^-1 at a doping level of 4.4x10^20 cm^-3. We also show that resistance of (Ba,La)SnO3 changes little even after a thermal cycle to 530 Deg. C in air, pointing to an unusual stability of oxygen atoms and great potential for realizing transparent high-frequency, high-power functional devices.Comment: 15 pages, 3 figure

Hepatic resection of metastatic tumor from serous cystadenocarcinoma of the ovary.

Metastatic carcinomas are the largest group of malignant tumors of the liver. But parenchymal liver metastasis from cystic ovarian adenocarcinoma is very rare. We report a case in which the resection of metastatic liver neoplasm from ovarian serous cystadenocarcinoma was done 7 yr after initial treatment. A 48-yr-old oriental housewife complained of easy fatigability and right lower quadrant discomfort. The hepatic mass was detected by ultrasonographic examination. Serum albumin, bilirubin, and aspartate aminotransferase/alanine aminotransferase were normal. Alkaline phosphatase level was slightly increased at 146 IU/L. A tumor marker study showed alpha-fetoprotein 0.97 IU/mL, carcinoembryonic antigen 0.965 ng/mL, cancer antigen 125 1,267 ng/mL and CA 19-9 106.1 ng/mL. The operation involved cholecystectomy and segmentectomy VI and VII of the liver. The patient recovered from the surgery without any complication. On the 10th postoperative day, the patient received a single-regimen chemotherapy with paclitaxel (Taxol, 155 mg/m(2) BSA) and was discharged. She has been carefully followed-up without any evidence of recurrence after completion of the remaining 5 cycles of chemo-therapy, at intervals of three weeks

COMPARISON OF GAIT ANALYSIS BETWEEN ADOLESCENT IDIOPATHIC SCOLIOSIS PATIENTS AND AGE MATCHED CONTROLS

The purpose of this study was to compare kinematic variables and surface EMG values between adolescent idiopathic scoliosis patients and age matched controls during a gait. Six male patients and five male healthy subjects were recruited for this study. Six cameras were used for 3D motion capture and selected joint angles were computed. Eight pairs of surface EMG electrodes were placed on latissimus dorsi, psoas, glutaeus medius, and biceps femoris. Results revealed that the scoliosis patients showed smaller hip joint angles compared to the values of the controls and vice versa for the trunk tilting angle. Small EMG activity of latissimus dorsi also found from the patient group. This meant that the scoliosis clearly influenced to the abnormal posture during a gait. Such results may be helpful to develop rehabilitation exercise or device