Improvement of the efficiency of triple junction n-i-p solar cells with hot-wire CVD proto- and microcrystalline silicon absorber layers

Hot-wire chemical vapour deposition (HWCVD) was applied for the deposition of intrinsic protocrystalline (proto-Si:H) and microcrystalline silicon (μc-Si:H) absorber layers in thin film solar cells. For a single junction μc-Si:H n-i-p cell on a Ag/ZnO textured back reflector (TBR) with a 2.0 μm i-layer, an 8.5% efficiency was obtained, which showed to be stable after 750 h of light-soaking. The short-circuit current density (J_sc) of this cell was 23.4 mA/cm², with a high open-circuit voltage (V_oc) and fill factor (FF) of 0.545 V and 0.67.Triple junction n-i-p cells were deposited using proto-Si:H, plasma-deposited proto-SiGe:H and μc-Si:H as top, middle and bottom cell absorber layers. With Ag/ZnO TBR's from our lab and United Solar Ovonic LLC, respective initial efficiencies of 10.45% (2.030 V, 7.8 mA/cm², 0.66) and 10.50% (2.113 V, 7.4 mA/cm², 0.67) were achieved.     

Validation of low-dose dobutamine magnetic resonance imaging for assessment of myocardial viability after infarction by serial imaging

Cine magnetic resonance imaging with low-dose dobutamine stimulation allows prediction of viability after infarction with an accuracy of 80%. In akinetic segments, however, viability tends to be underestimated.     

Serological study of the occurrence of L. hardjo in sheep in The Netherlands

Sheep (3918) from 137 farms in the regions of North-, West- and Mid-Netherlands and Gelderland were serologically investigated for the presence of antibodies against Leptospira hardjo. Antibodies were detected in 3.3% of the sheep. There were large regional differences with respect to both the percentage of positive sheep and the percentage of positive flocks. All sera from sheep in Gelderland were negative. In West- en Mid-Netherlands there were 0.9 and 6.5% positive sera, respectively, and 19.4 and 32.7% positive flocks. The percentage of positive sheep per positive flocks varied from 1 tot 51.6. Serological positive sheep were from farms with and without cattle. On farms with cattle, there was no clear relationship between serologically sheep and the presence of hardjo antibodies in cattle. It thus seems plausible that sheep can be infected with hardjo independently of cattle.     

Effect of low dose aspirin on thrombus formation at arterial and venous microanastomoses and on the tissue microcirculation

In free flap/replantation surgery, failure is usually associated with thrombotic occlusion of a microvascular anastomosis (risk zone I) or, on occasion, flow impairment in the microcirculation of the transferred or replanted tissue (risk zone II). The objective of this study is to describe the effect of low dose aspirin on blood flow at both risk zones in microvascular surgery. Risk zone I: In rat femoral arteries and veins, thrombus formation was measured at the anastomoses using transillumination and videomicroscopy. Forty male Wistar rats were assigned in equal numbers to four groups: either arterial or venous injury with either aspirin (5 mg/kg systemically) or saline treatment. We found that aspirin significantly reduces thrombus formation at the venous anastomosis (p = 0.001). Risk zone II: In the isolated rat cremaster muscle downstream from an arterial anastomosis, we measured capillary perfusion, arteriolar diameters, and the appearance of platelet emboli for 6 hours in the muscle microcirculation. Sixteen male Wistar rats in two equal groups received either aspirin (5 mg/kg systemically) or saline. We found that in aspirin-treated animals, capillary perfusion is significantly (p = 0.002) improved, whereas arteriolar diameters and emboli only slightly increased. In conclusion, low dose aspirin inhibits anastomotic venous thrombosis and improves microcirculatory perfusion in our rat model. These studies provide quantitative data confirming and clarifying the beneficial effects of low dose aspirin in microvascular surgery.     

Probability of detecting antibodies to bovine herpesvirus 1 in bulk milk after the introduction of a positive animal on to a negative farm

The purpose of this study was to assess the probability that the introduction of one or more bovine herpesvirus 1 (BHV-1)-seropositive animals would result in the bulk milk of a clean herd becoming BHV-1-positive. Probability calculations (stochastic and deterministic) were based on the distribution of the log(titre) of 828 positive animals and the daily milk production of the herds and of the individual cows. They showed that the probability in average sized herds of 45 dairy cows is only between 10 and 25 per cent and that even in small herds of 25 cows the introduction of a positive animal would go undetected in the majority of cases. It is concluded that if the bulk milk has become BHV-1-positive it is most likely that the infection has spread.     

SPET-generated colour-coded polar maps to quantify 99Tcm-MIBI and 123I-BMIPP uptake in chronically dysfunctional myocardium: comparison with coronary anatomy and wall motion

The combined use of 123I-BMIPP and 99Tcm-MIBI SPET imaging has been proposed as an alternative to PET for the non-invasive detection of jeopardized myocardium after a myocardial infarction, a mismatch accurately indicating jeopardized but still viable tissue. In this paper, a new quantitative approach is described, expressing the presence and degree of mismatch as the percentage of the left ventricular surface globally as well as for each major epicardial artery by means of clearly identified colour-coded polar maps. With this method, the relative proportion of normal and scar tissue, each characterized by a specific colour, is measured using thresholds of 99Tcm-MIBI uptake of 60% and 30% of the expected mean normal value respectively, whereas the presence and extent of mismatch between 99Tcm-BMIPP and 99Tcm-MIBI are calculated only between these two thresholds, typically corresponding to a reduction in flow associated with a possible but uncertain post-revascularization recovery. Applied to 15 patients with severely impaired left ventricular function after a myocardial infarction, small intra- and inter-observer differences were noted in the assessment of the relative proportion of normal, mismatched and scar tissue. More specifically, analysing the variability in the calculated percent mismatch, good reproducibility was observed, with intra- and inter-observer correlation coefficients of 0.96 and 0.94 respectively, a mean (+/- S.D.) intra-observer difference of 0.25 +/- 2.0% for the left ventricle globally, 1.65 +/- 2.9% for the left anterior descending artery (LAD), -1.56 +/- 3.6% for the left circumflex artery (LCX) and -1.24 +/- 2.8% for the right coronary artery (RCA) territories, and mean inter-observer variability of 0.91 +/- 2.4% for the left ventricle globally, -1.51 +/- 3.0% for the LAD, -0.53 +/- 2.9% for the LCX and -0.34 +/- 3.9% for the RCA territories. Using the second standard deviation of the inter-observer difference as a criterion of significance, a significant mismatch between 99Tcm-BMIPP and 99Tcm-MIBI was noted in 13 arterial territories, corresponding to significant stenoses on coronary angiogram and/or wall motion abnormalities in all cases. These results suggest that this new quantitative method, showing good reproducibility, may constitute a reliable and interesting tool for the non-invasive evaluation of myocardial viability with SPET.     

Molecular analysis of protein domain function encoded by the myb-homologous maize genes C1, Zm 1 and Zm 38

Two maize genes, Zm 1 and Zm 38, related to the regulatory anthocyanin gene C1 were analyzed molecularly and used for fusion constructs in transient domain swapping experiments with the C1 wild-type gene. It was shown that both genes (Zm 1 and Zm 38) influence the expression of the A1 locus, a target gene for C1. Zm 1 activates the A1 promoter, however it does not turn on the whole anthocyanin pathway. The Zm 38 gene product shows functions similar to C1-I, a dominant inhibitor of the C1 wild-type gene. Concerning the trans-inhibition by C1-I two effects seem to be involved, competition for binding and formation of heterodimers. Further analysis of C1 function was carried out by a fine structure analysis of C1 mutants induced by the insertion and excision of transposable elements. These experiments indicate that for the activating domain of the protein, the formation of an alpha helix seems to be more important than a high negative charge.     

Herstellung von Synthesegas aus Braunkohle

Production of synthesis gas from lignite . The production of methanol synthesis gas from lignite is explained for the high-temperature Winkler process. The influence of experimental factors on the economics of the overall process is indicated, and the production of methanol synthesis gas from lignite, residual oil, and natural gas is compared. The article concludes by presenting further developments of the high-temperature Winkler process.