In Situ deposition of YBCO high-T(sub c) superconducting thin films by MOCVD and PE-MOCVD

Metalorganic Chemical Vapor Deposition (MOCVD) offers the advantages of a high degree of compositional control, adaptability for large scale production, and the potential for low temperature fabrication. The capability of operating at high oxygen partial pressure is particularly suitable for in situ formation of high temperature superconducting (HTSC) films. Yttrium barium copper oxide (YBCO) thin films having a sharp zero-resistance transition with T( sub c) greater than 90 K and Jc approx. 10 to the 4th power A on YSZ have been prepared, in situ, at a substrate temperature of about 800 C. Moreover, the ability to form oxide films at low temperature is very desirable for device applications of HTSC materials. Such a process would permit the deposition of high quality HTSC films with a smooth surface on a variety of substrates. Highly c-axis oriented, dense, scratch resistant, superconducting YBCO thin films with mirror-like surfaces have been prepared, in situ, at a reduced substrate temperature as low as 570 C by a remote microwave-plasma enhanced metalorganic chemical vapor deposition (PE-MOCVD) process. Nitrous oxide was used as a reactant gas to generate active oxidizing species. This process, for the first time, allows the formation of YBCO thin films with the orthorhombic superconducting phase in the as-deposited state. The as-deposited films grown by PE-MOCVD show attainment of zero resistance at 72 K with a transition width of about 5 K. MOCVD was carried out in a commercial production scale reactor with the capability of uniform deposition over 100 sq cm per growth run. Preliminary results indicate that PE-MOCVD is a very attractive thin film deposition process for superconducting device technology

In-situ deposition of YBCO high-Tc superconducting thin films by MOCVD and PE-MOCVD

Metal-Organic Chemical Vapor Deposition (MOCVD) offers the advantages of a high degree of compositional control, adaptability for large scale production, and the potential for low temperature fabrication. The capability of operating at high oxygen partial pressure is particularly suitable for in situ formation of high temperature superconducting (HTSC) films. Yttrium barium copper oxide (YBCO) thin films having a sharp zero-resistance transition with T(sub c) greater than 90 K and J(sub c) of approximately 10(exp 4) A on YSZ have been prepared, in situ, at a substrate temperature of about 800 C. Moreover, the ability to form oxide films at low temperature is very desirable for device applications of HTSC materials. Such a process would permit the deposition of high quality HTSC films with a smooth surface on a variety of substrates. Highly c-axis oriented, dense, scratch resistant, superconducting YBCO thin films with mirror-like surfaces have been prepared, in situ, at a reduced substrate temperature as low as 570 C by a remote microwave-plasma enhanced metal-organic chemical vapor deposition (PE-MOCVD) process. Nitrous oxide was used as a reactant gas to generate active oxidizing species. This process, for the first time, allows the formation of YBCO thin films with the orthorhombic superconducting phase in the as-deposited state. The as-deposited films grown by PE-MOCVD show attainment of zero resistance at 72 K with a transition width of about 5 K. MOCVD was carried out in a commercial production scale reactor with the capability of uniform deposition over 100 sq cm per growth run. Preliminary results indicate that PE-MOCVD is a very attractive thin film deposition process for superconducting device technology

Multiple feedback loops through cytokinin signaling control stem cell number within the Arabidopsis shoot meristem

A central unanswered question in stem cell biology, both in plants and in animals, is how the spatial organization of stem cell niches are maintained as cells move through them. We address this question for the shoot apical meristem (SAM) which harbors pluripotent stem cells responsible for growth of above-ground tissues in flowering plants. We find that localized perception of the plant hormone cytokinin establishes a spatial domain in which cell fate is respecified through induction of the master regulator WUSCHEL as cells are displaced during growth. Cytokinin-induced WUSCHEL expression occurs through both CLAVATA-dependent and CLAVATA-independent pathways. Computational analysis shows that feedback between cytokinin response and genetic regulators predicts their relative patterning, which we confirm experimentally. Our results also may explain how increasing cytokinin concentration leads to the first steps in reestablishing the shoot stem cell niche in vitro

Fatty liver and insulin resistance in obese Zucker rats: No role for mitochondrial dysfunction

The relationship between insulin resistance and mitochondrial function is of increasing interest. Studies looking for such interactions are usually made in muscle and only a few studies have been done in liver, which is known to be a crucial partner in whole body insulin action. Recent studies have revealed a similar mechanism to that of muscle for fat-induced insulin resistance in liver. However, the exact mechanism of lipid metabolites accumulation in liver leading to insulin resistance is far from being elucidated. One of the hypothetical mechanisms for liver steatosis development is an impairment of mitochondrial function. We examined mitochondrial function in fatty liver and insulin resistance state using isolated mitochondria from obese Zucker rats. We determined the relationship between ATP synthesis and oxygen consumption as well as the relationship between mitochondrial membrane potential and oxygen consumption. In order to evaluate the quantity of mitochondria and the oxidative capacity we measured citrate synthase and cytochrome c oxidase activities. Results showed that despite significant fatty liver and hyperinsulinemia, isolated liver mitochondria from obese Zucker rats display no difference in oxygen consumption, ATP synthesis, and membrane potential compared with lean Zucker rats. There was no difference in citrate synthase and cytochrome c oxidase activities between obese and lean Zucker rats in isolated mitochondria as well as in liver homogenate, indicating a similar relative amount of hepatic mitochondria and a similar oxidative capacity. Adiponectin, which is involved in bioenergetic homeostasis, was increased two-fold in obese Zucker rats despite insulin resistance. In conclusion, isolated liver mitochondria from lean and obese insulin-resistant Zucker rats showed strictly the same mitochondrial function. It remains to be elucidated whether adiponectin increase is involved in these results

Distribution of adipose tissue: Quantification and relationship with hepatic steatosis and vascular profiles of type 2 diabetic patients with metabolic syndrome

AimAs the distribution of fat is increasingly related to cardiovascular events, we examined whether or not abdominal-fat quantification using magnetic resonance imaging (MRI) software is reliable, and whether or not it is related to clinical markers of fat distribution as well as to metabolic and vascular status. Methods We recorded the anthropometric measurements of 34 obese type 2 diabetic patients with metabolic syndrome. The patients were enrolled to evaluate their abdominal (visceral and subcutaneous) adipose tissue by single-slice L3–L4 MRI. Manual and automated analyses were compared. The relationships between anthropometric measurements, biological markers and intima-media thickness of the common carotid artery were also assessed. Results We validated the automated software to quantify abdominal-fat deposition with MRI compared with manual measurements (r2 = 0.95). The waist-to-hip-circumference ratio (WHR) was the only clinical parameter that correlated with the proportion and quantity of visceral and subcutaneous abdominal-adipose tissue evaluated by MRI (r = 0.60). In addition, fat repartition as evaluated by WHR was related to hepatic steatosis parameters (ferritin and ALAT) and to intima-media thickness, whereas simple waist circumference was not a determinant in these obese patients. We also showed that the adiponectin-to-leptin ratio was related to adipose tissue distribution. Conclusion Distribution of abdominal fat, as evaluated by MRI, can be reflected by clinical determination of the WHR. Differences in regional accumulations of abdominal fat may be specifically related to variations in the risks of steatosis and vascular rigidity among obese type 2 diabetic patients

Combination of blood tests for significant fibrosis and cirrhosis improves the assessment of liver-prognosis in chronic hepatitis C

BACKGROUND: Recent longitudinal studies have emphasised the prognostic value of noninvasive tests of liver fibrosis and cross-sectional studies have shown their combination significantly improves diagnostic accuracy. AIM: To compare the prognostic accuracy of six blood fibrosis tests and liver biopsy, and evaluate if test combination improves the liver-prognosis assessment in chronic hepatitis C (CHC). METHODS: A total of 373 patients with compensated CHC, liver biopsy (Metavir F) and blood tests targeting fibrosis (APRI, FIB4, Fibrotest, Hepascore, FibroMeter) or cirrhosis (CirrhoMeter) were included. Significant liver-related events (SLRE) and liver-related deaths were recorded during follow-up (started the day of biopsy). RESULTS: During the median follow-up of 9.5 years (3508 person-years), 47 patients had a SLRE and 23 patients died from liver-related causes. For the prediction of first SLRE, most blood tests allowed higher prognostication than Metavir F [Harrell C-index: 0.811 (95% CI: 0.751-0.868)] with a significant increase for FIB4: 0.879 [0.832-0.919] (P = 0.002), FibroMeter: 0.870 [0.812-0.922] (P = 0.005) and APRI: 0.861 [0.813-0.902] (P = 0.039). Multivariate analysis identified FibroMeter, CirrhoMeter and sustained viral response as independent predictors of first SLRE. CirrhoMeter was the only independent predictor of liver-related death. The combination of FibroMeter and CirrhoMeter classifications into a new FM/CM classification improved the liver-prognosis assessment compared to Metavir F staging or single tests by identifying five subgroups of patients with significantly different prognoses. CONCLUSIONS: Some blood fibrosis tests are more accurate than liver biopsy for determining liver prognosis in CHC. A new combination of two complementary blood tests, one targeted for fibrosis and the other for cirrhosis, optimises assessment of liver-prognosis

Nutritive value of palm kernel meal in diets for growing rabbits

The aim of this work was to determine the nutritive value of palm kernel meal (PKM) in diets for growing rabbits. In Experiment 1, 20 New Zealand × Californian growing rabbits 50 d-old were used to determine energy, crude protein, fibre and fat digestibility of PKM. The nutritive value was estimated by the difference method using a basal diet and another diet made by substituting 200 g/kg of basal diet with PKM. Energy, crude protein, ether extract and neutral detergent fibre of PKM digestibilities were, respectively, 0.549 (±0.056, SE), 0.541 (±0.069), 0.850 (±0.048) and 0.430 (±0.101), and the digestible energy concentration was 10.9 MJ/kg (±1.03) DM. In Experiment 2, 412 rabbits were allocated at random to the two experimental diets to measure growing performance. Inclusion of 200 g PKM/kg in the diet did not affect feed or digestible energy intake but decreased slightly (by around 5%) average daily gain (P = 0.003) and feed efficiency (P < 0.001). Neither mortality nor Clostridium perfringens counts in soft faeces were affected by type of diet. Palm kernel meal can be considered a palatable source of fibre, protein and fat for rabbits and can substitute significant amounts of other fibrous ingredients in the diet without adverse effects on growth performance

The food contaminant fumonisin B1 reduces the maturation of porcine CD11R1+ intestinal antigen presenting cells and antigen-specific immune responses, leading to a prolonged intestinal ETEC infection

Consumption of food or feed contaminated with fumonisin B1 (FB1), a mycotoxin produced by Fusarium verticillioides, can lead to disease in humans and animals. The present study was conducted to examine the effect of FB1 intake on the intestinal immune system. Piglets were used as a target and as a model species for humans since their gastro-intestinal tract is very similar. The animals were orally exposed to a low dose of FB1 (1 mg/kg body weight FB1) for 10 days which did not result in clinical signs. However, when compared to non-exposed animals, FB1-exposed animals showed a longer shedding of F4+ enterotoxigenic Escherichia coli (ETEC) following infection and a lower induction of the antigen-specific immune response following oral immunization. Further analyses to elucidate the mechanisms behind these observations revealed a reduced intestinal expression of IL-12p40, an impaired function of intestinal antigen presenting cells (APC), with decreased upregulation of Major Histocompatibility Complex Class II molecule (MHC-II) and reduced T cell stimulatory capacity upon stimulation. Taken together, these results indicate an FB1-mediated reduction of in vivo APC maturation