Wide-bandgap oxide semiconductors have received significant attention as they can produce devices with high output and breakdown voltage. p-Type conductivity control is essential to realize bipolar devices. Therefore, as a rare wide-bandgap p-type oxide semiconductor, NiO (3.7 eV) has garnered considerable attention. In view of the heterojunction device with Ga2O3 (4.5–5.0 eV), a p-type material with a large bandgap is desired. Herein, we report the growth of a Ni1-xMgxO thin film, which has a larger bandgap than NiO, on α-Al2O3 (0001) substrates that was developed using the mist chemical vapor deposition method. The Ni1-xMgxO thin films epitaxially grown on α-Al2O3 substrates showed crystallographic orientation relationships identical to those of NiO thin films. The Mg composition of Ni1-xMgxO was easily controlled by the Mg concentration of the precursor solution. The Ni1-xMgxO thin film with a higher Mg composition had a larger bandgap, and the bandgap reached 3.9 eV with a Ni1-xMgxO thin film with x = 0.28. In contrast to an undoped Ni1-xMgxO thin film showing insulating properties, the Li-doped Ni1-xMgxO thin film had resistivities of 101–105 Ω∙cm depending on the Li precursor concentration, suggesting that Li effectively acts as an acceptor.

Maternal nutritional status during pregnancy is an important determinant of fetal growth. Although the effects of several nutrients and foods have been well examined, little is known about the relationship of overall maternal diet in pregnancy to fetal growth, particularly in non-Western populations. We prospectively examined the relationship of maternal dietary patterns in pregnancy to neonatal anthropometric measurements at birth and risk of small-for-gestational-age (SGA) birth among 803 Japanese women with live-born, singleton, term deliveries. Maternal diet in pregnancy was assessed using a validated, self-administered diet history questionnaire. Dietary patterns from thirty-three predefined food groups (g/4184 kJ) were extracted by cluster analysis. The following three dietary patterns were identified: the ‘meat and eggs’ (n 326), ‘wheat products’, with a relatively high intake of bread, confectioneries and soft drinks (n 303), and ‘rice, fish and vegetables’ (n 174) patterns. After adjustment for potential confounders, women in the ‘wheat products’ pattern had infants with the significantly lowest birth weight (P = 0·045) and head circumference (P = 0·036) among those in the three dietary patterns. Compared with women in the ‘rice, fish and vegetables’ pattern, women in the ‘wheat products’ pattern had higher odds of having a SGA infant for weight (multivariate OR 5·2, 95 % CI 1·1, 24·4), but this was not the case for birth length or head circumference. These results suggest that a diet high in bread, confectioneries, and soft drinks and low in fish and vegetables during pregnancy might be associated with a small birth weight and an increased risk of having a SGA infant.

Although several nutrients and foods are suggested to be preventive against postpartum depression, all previous studies have primarily focused on single nutrients or foods. In contrast, studies on dietary patterns, namely the measurement of overall diet by considering the cumulative effects of nutrient, may provide new insights into the influence of diet on postpartum depression. We prospectively examined the association between dietary patterns during pregnancy and the risk of postpartum depression among 865 Japanese women. Diet was assessed with a validated, self-administered diet history questionnaire. Dietary patterns from thirty-three predefined food groups (energy-adjusted food (g/d)) were extracted by factor analysis. Postpartum depression was defined as present when the subjects had an Edinburgh Postnatal Depression Scale score of ≥ 9 at 2–9 months postpartum. A total of 121 women (14·0 %) were classified as having postpartum depression. Three dietary patterns were identified: ‘Healthy’, ‘Western’ and ‘Japanese’ patterns. After adjustment for potential confounders, neither the ‘Healthy’ nor the ‘Japanese’ pattern was related to the risk of postpartum depression. Compared with the first quartile of the ‘Western’ pattern, only the second quartile was independently related to a decreased risk of postpartum depression (multivariate OR 0·52, 95 % CI 0·30, 0·93), although no evident exposure–response associations were observed (P for trend = 0·36). The present study failed to substantiate clear associations between dietary patterns and the risk of postpartum depression. Further studies with more accurate measurements are warranted to confirm the relationship between dietary patterns and the risk of postpartum depression.

Increased homocysteine levels might accelerate dopaminergic cell death in Parkinson's disease (PD) through neurotoxic effects; thus, increasing intake of B vitamins involved in the regulation of homocysteine metabolism might decrease the risk of PD through decreasing plasma homocysteine. However, epidemiological evidence for the association of dietary B vitamins with PD is sparse, particularly in non-Western populations. We conducted a hospital-based case–control study in Japan to examine associations between dietary intake of folate, vitamin B6, vitamin B12 and riboflavin and the risk of PD. Patients with PD diagnosed using the UK PD Society Brain Bank criteria (n 249) and controls without neurodegenerative diseases (n 368) were recruited. Dietary intake during the preceding month was assessed at the time of study recruitment using a validated, self-administered, semi-quantitative, comprehensive diet history questionnaire. After adjustment for potential dietary and non-dietary confounding factors, intake of folate, vitamin B12 and riboflavin was not associated with the risk of PD (P for trend = 0·87, 0·70 and 0·11, respectively). However, low intake of vitamin B6 was associated with an increased risk of PD, independent of potential dietary and non-dietary confounders. Multivariate OR (95 % CI) for PD in the first, second, third and fourth quartiles of vitamin B6 were 1 (reference), 0·56 (0·33, 0·94), 0·69 (0·38, 1·25) and 0·48 (0·23, 0·99), respectively (P for trend = 0·10). In conclusion, in the present case–control study in Japan, low intake of vitamin B6, but not of folate, vitamin B12 or riboflavin, was independently associated with an increased risk of PD.

Animal cloning methods are now well described and are becoming routine. Yet, the frequency at which live cloned offspring are produced remains below 5%, irrespective of the nuclear donor species or cell type. One possible explanation is that the reprogramming factor(s) of each oocyte is insufficient or not properly adapted for the receipt of a somatic cell nucleus, because it is naturally prepared only for the receipt of a gamete. Here, we have increased the oocyte volume by oocyte fusion and examined its subsequent development. We constructed oocytes with volumes two to nine times greater than the normal volume by the electrofusion or mechanical fusion of intact and enucleated oocytes. We examined their in vitro and in vivo developmental potential after parthenogenetic activation, intracytoplasmic sperm injection (ICSI) and somatic cell nuclear transfer (SCNT). When the fused oocytes were activated parthenogenetically, most developed to morulae or blastocysts, regardless of their original size. Diploid fused oocytes were fertilized by ICSI and developed normally and after embryo transfer, we obtained 12 (4–15%) healthy and fertile offspring. However, enucleated fused oocytes could not support the development of mice cloned by SCNT. These results suggest that double fused oocytes have normal potential for development after fertilization, but oocytes with extra cytoplasm do not have enhanced reprogramming potential.

Background. An ecological analysis found that the docosahexaenoic acid content in mother's milk and seafood intake were inversely correlated with postpartum depression. This prospective study investigated the relationship of consumption of selected high-fat foods and specific types of fatty acids with the risk of postpartum depression.

Method. The subjects were 865 Japanese women. Dietary data were obtained from a self-administered diet history questionnaire during pregnancy. The Edinburgh Postnatal Depression Scale (EPDS) was used for the evaluation of postpartum depression. Adjustment was made for age, gestation, parity, cigarette smoking, family structure, family income, education, changes in diet in the previous month, season when data at baseline were collected, body mass index, time of delivery before the second survey, medical problems in pregnancy, baby's sex and baby's birthweight.

Results. The percentage of women with high depression scores was 14·0%. No evident dose–response associations were observed between intake of fish, meat, eggs, dairy products, total fat, saturated fatty acids, monounsaturated fatty acids, n-3 polyunsaturated fatty acids, n-6 polyunsaturated fatty acids, linoleic acid, α-linolenic acid, arachidonic acid, eicosapentaenoic acid or docosahexaenoic acid and the ratio of n-3 to n-6 polyunsaturated fatty acids and the risk of postpartum depression. However, there was an inverted J-shaped relationship between intake of n-3 polyunsaturated fatty acids and docosahexaenoic acid and the risk of postpartum depression.

Conclusions. This study failed to substantiate a clear inverse relationship between fish and n-3 polyunsaturated fatty acid intake and postpartum depression. Further investigations are needed to determine whether fish and n-3 polyunsaturated fatty acid consumption is preventive against postpartum depression.

The anisotropically biaxial strain in a-plane AlGaN on GaN is investigated by X-ray diffraction analysis of the heterostructure of AlGaN and GaN grown on r-plane sapphire. The AlGaN layer with a low AlN molar fraction or small thickness is coherently grown on the GaN layer both along the m-axis and c-axis. An increase in AlN molar fraction or thickness in AlGaN, results in a slight relaxation of AlGaN only in one direction due to tensile stress along the c-axis, which is caused by the underlying GaN layer during the growth. The cause of the relaxation of AlGaN in one direction is thought to be a large anisotropically biaxial stress.

Mg-doped p-type a-plane GaN films were grown on unintentionally doped a-plane GaN templates by metalorganic vapor phase epitaxy (MOVPE). The Mg concentration in a-plane GaN increased with increasing Mg source gas flow rate. A maximum hole concentration of 2.0 × 1018 cm-3 with a hole mobility of 4.5 cm2/Vs and resistivity of 0.7 Ω·cm were achieved. The activation ratio was 5.0 × 10-2. It was found that a maximum hole concentration in p-type a-plane GaN was higher than that in p-type c-plane GaN. The activation energy of Mg acceptors in p-type a-plane GaN with the maximum hole concentration was found to be 118 meV by temperature-dependent Hall-effect measurement.

The heteroepitaxial growth of a GaN single crystal by metal-organic vapor phase epitaxy on a 4H-SiC (3038) substrate was demonstrated. The crystallographic orientation of GaN was found to be dependent on growth pressure. When the growth pressure was 1000 hPa, the orientation of the GaN single crystal was consistent with that of the SiC substrate, where the c-plane of the GaN was single crystal tilted 54.7° from the surface plane. Then, we fabricated a violet-light-emitting diode (LED) with a GaInN multiple-quantum-well (QW) active layer grown on the GaN layer, which coherently grew on the 4H-SiC (3038 ) substrate. The blue shift of the peak wavelength with increasing injection current of up to 100 mA was confirmed to be two times smaller than that of a conventional LED on a c-plane sapphire substrate due to a low internal polarization.

Nitride-based blue-light-emitting diodes having a moth-eye structure were fabricated on the backside of a 6H-SiC substrate. The light extraction efficiency and the corresponding output power were increased by 3.8 times compared with those of an LED having the conventional structure. The results of theoretical analysis agree with these findings.