The analysis of silicon solar cell contacts having an H-bar front grid pattern is extended by enabling the contact resistivity to be inferred from the measurement of total series resistance and the ...determination of six individual components of series resistance. Analysis of the contact system was completed for a representative 19% cell fabricated from a 156-mm pseudosquare p-Cz wafer using standard production processes, including phosphorus ion implantation, thermal oxide surface passivation, silicon nitride deposition, and screen-printing and firing of front silver gridlines and busbars, back silver soldering pads, and back aluminum contact. Gridline width was measured to be 80 μm after firing, with an average thickness of 7.4 μm and an effective resistivity of 4.7 μΩ·cm. Contact resistivity to the uniform 91 Ω/□ emitter was inferred to be 5.3 mΩ·cm 2 from the total series resistance and its components. Using these values, gridline spacing was optimized for maximum efficiency (1.7 mm, 91 lines, 19.1%, 0.040/W) or minimum silver cost (2.1 mm, 74 lines, 19.0%, 0.038/W). The analysis methodology was further applied to examine the impact of gridline width and silver pricing on cell efficiency and incremental cost. Such analysis can serve as a guideline for future contact system designs when the cost of silver changes or when printing technology allows narrower lines.
Supercritical water gasification (SCWG) of the wood tar fraction soluble in water is discussed. The mixture is collected downstream of an updraft wood gasification plant and presents tar compounds ...typical of low-temperature pyrolysis, with the highest yields attained by acetic acid, levoglucosan and 1-hydroxy-2-propanone. SCWG tests, using a laboratory-scale reactor with a plug-flow behavior, temperatures of 723–821
K, residence times of 46–114
s and initial total organic carbon (TOC) contents of 6.5–31
g/l (pressure equal to 25
MPa), show TOC conversion roughly between 30% and 70%. The corresponding yields of gas (l) with respect to the initial TOC contents (g) vary from 0.4 to 1. Gasification of TOC is well described by an irreversible, first-order, Arrhenius rate reaction with an activation energy of 75.7±22
kJ/mol and a pre-exponential factor of 897±30
s
−1. Quantification of 23 tar compounds of the product stream shows the prompt conversion of sugars and complex phenols, with the formation of intermediate products, such as furfurals, which successively decompose, and more thermally resistant species, such as acetic acid, propionic acid, 1,2-ethanediol, ketones and especially cresols and phenols.
Thrombolytic therapy with recombinant tissue plasminogen activator (rtPA) is approved in the United States for treatment of acute ischemic stroke. Approval was granted after a large, randomized, ...placebo-controlled study by the National Institute of Neurological Disorders and Stroke (NINDS) showed a significant improvement in 3-month outcomes with rtPA despite a significant risk for symptomatic hemorrhage. Two other trials, the first and second European Cooperative Acute Stroke Study (ECASS I and II), have shown comparable results, but neither was statistically positive for the predefined primary end point. An analysis of the risk/benefit profile of rtPA therapy based on the results of these three trials indicates that the treatment is effective and, when administered within 3 hours of symptom onset at a dose of 0.9 mg/kg, the benefits by far outweigh the risks for eligible patients. Even with the 6-hour time window of the two ECASS trials, a combined analysis of the three studies shows the number of disabled or dead patients to be significantly reduced. Preliminary data collected on the use of rtPA outside of clinical trials in the United States and Europe suggest that, when rtPA is used according to the trial protocol, the risks and benefits are similar to those observed in clinical trials. However, even within the United States, rtPA is underutilized. The most substantial treatment barrier is the narrow time window, which may be expanded if long-term experience shows that this is possible. Most stroke patients arrive at the hospital too late to be eligible for screening and treatment. Education of the public and physicians may help to overcome this difficulty.
To investigate the predictive value of 1 year subtraction MRI (sMRI) on activity and progression over the next 4 years in early phase multiple sclerosis (MS). To compare sensitivity of sMRI and ...contrast enhanced MRI towards disease activity.
The study was performed on 127 MS patients with brain MRI within 5 years of symptom onset (y0), after 1 year (y1) and after 5 years (y5). Measures of clinical (Expanded Disability Status Scale, relapse rate) and conventional MRI outcomes (brain parenchyma fraction (BPF); T2 lesion volume (T2LV); contrast enhancing lesions (CEL)) were available at all time points. sMRI was obtained from y1-y0, y5-y1 and y5-y0 image pairs and the number of new, enlarged, resolved and regressed lesions was counted.
One year lesion change measured by sMRI predicted sMRI lesion change (p<0.0001), BPF and T2LV (p<0.05) changes, as well as clinical relapse rate (p<0.02) in the subsequent 4 years. sMRI measures were retained in stepwise predictive models that included other candidate MRI predictors. Active lesions on sMRI over a 1, 4 or 5 year interval provided a more sensitive assessment of disease activity than number of CEL at y0, y1 and/or y5: 83%, 93% and 90% of patients without CEL showed sMRI activity during the y1-y0, y5-y1, and y5-y0 intervals.
sMRI is a feasible and sensitive tool for detecting MS activity and may provide an alternative to contrast enhanced MRI in clinical practice, particularly in cases where CEL are not available or inconclusive. Furthermore, sMRI metrics combined with conventional MRI outcomes (CEL, T2LV, BPF) can increase the prediction of longer term MRI activity and progression.
A homogeneous distribution of ferroelectric nanoinclusions was observed by optical second harmonic generation in epitaxial films of hexagonal RMnO3 (R = Y, Dy, Ho, Er) grown on ZrO2(Y2O3) substrates. ...The inclusions correspond to secondary orientations in the c-axis-oriented films. Their volume density is in the range of 10(-3) and their occurrence is independent of growth technique and film thickness in the range of 20-1000 nm. The inclusions behave as preferentially polarized ferroelectric nanodomains whereas the epitaxial film is in a ferroelectric single-domain state. In addition, the antiferromagnetic phase exhibits nanodomains of < 100 nm which is three orders of magnitude below the extension of bulk antiferromagnetic domains in RMnO3. Indications for a polarization-induced magnetic order different from that of the bulk are discussed.
Using retroviral vectors encoding enhanced green fluorescent protein (EGFP), we addressed to what extent expression of retroviral transgenes in hematopoietic cells depends on the multiplicity of ...infection (MOI) and on the half-life of the encoded protein. We show that an elevation of the MOI not only elevates the frequency of transduced cells, but also increases transgene expression levels and reduces interanimal variability in vivo (hematopoietic cells of C57BL/6J mice analyzed 13 weeks after transplantation). This suggests that the MOI has to be carefully controlled and should be adapted as desired for clinical studies when evaluating vector performance in preclinical models. The impact of protein stability is demonstrated by comparing vectors expressing EGFP or a destabilized variant with a C-terminal PEST-sequence, d2EGFP. The loss of expression with d2EGFP was more pronounced in terminally differentiated cells of the peripheral blood (>30 fold) than in progenitor cells (five- to 10-fold), indicating a stronger transcription of the retroviral promoter in progenitor cells and a predominant role of protein inheritance over de novo synthesis of transgenic protein in mature blood cells. This analysis reveals an important and differentiation-dependent contribution of protein half-life to the expression of retroviral vectors in hematopoietic cells, establishes d2EGFP as a more accurate reporter for determination of vector transcription, and also suggests that preclinical data obtained under conditions of high transduction rates or with vectors expressing stable reporter proteins require careful interpretation.
There were a total of 12 documented Panax quinquefolius (American Ginseng) in the only known population in Louisiana in 1986. Our reassessment of the population in 2016 found 16 plants. We suggest ...that the long-term persistence of this tiny American Ginseng population indicates that simple matrix-population models may be overestimating quasi-extinction numbers and minimum viable populations, perhaps as a result of failing to sufficiently consider influences of environmental conditions. We further suggest that this, the southernmost documented population of the species in the US, has endured beyond expectation but remains at acute risk of extirpation and that any population-specific genes are at risk of loss if no intervention is made to protect the population.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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