Lithographic patterning of superconducting YBCO films

Microbridges of YBa₂Cu₃O₇ thin films have been fabricated by conventional photolithography and wet chemical etching using EDTA, and by the lift-off lithography technique. The variation of etch rate with etch time, etchant temperature, and post-deposition sintering temperature has been studied. It has been shown that both techniques are useful for film patterning. However, an additional sintering step is necessary for the chemically etched sample to regain the original film properties. An order of increase in critical current density is observed for the patterned film.     

Three sibs with mild variety of osteopetrosis

We report three sibs with mild autosomal recessive variety of osteopetrosis. The prominent clinical features were short stature, malocclusion of teeth, hepatosplenomegaly and a typical facial appearance. The only atypical features were microcephaly, a normal upper segment to lower segment ratio and a normal arm span.     

Interdiffusion in PbIn thin film couples

Interdiffusion in PbIn thin film couples has been examined by an X-ray diffraction technique. Initial results indicate that the interdiffusion in such couples is significantly faster than that expected from reported bulk data.     

The functional approach in biology

The concepts of structural and functional approaches are analysed. The existence of a logical limit to the domain of applicability of the structural approach is indicated. Some sources of possible failure of the structural method in biology are pointed out. Two fundamental characteristics of biological systems, inductive development and inductive functioning, necessitating the functional approach are discussed.     

Determination of mixing time in BOF process by a cold model study

Mixing time in a BOF process has been studied using a 1/14 water-air model. The study shows that for a simulated cold model, mixing time is independent of jet Froude number. For a partially simulated model, mixing time was found to be inversely proportional to square root of bath height to diameter ratio. This is in agreement with the similarity condition.     

Superiority of nitrate-enhanced 201Tl over conventional redistribution 201Tl imaging for prognostic evaluation after myocardial infarction and thrombolysis

BACKGROUND: 201Tl imaging has been widely used for postinfarction risk stratification. However, thrombolytic therapy and aspirin have significantly changed outcome, and there are few nuclear imaging studies that assess prognosis in such patients. Furthermore, newer techniques of 201Tl imaging, such as reinjection and nitrate-enhanced rest 201Tl imaging, have been shown to improve the detection of viable but jeopardized myocardium. METHODS AND RESULTS: We studied 100 consecutive patients, who remained event free 6 weeks after myocardial infarction and thrombolysis. Patients underwent conventional exercise and 4-hour redistribution imaging, followed on a separate day by nitrate-enhanced rest 201Tl study. Planar images were reported semiquantitatively by two experienced observers blinded to clinical data. Redistribution and rest injection images were classified as demonstrating reversible ischemia if they showed improvement in uptake by at least two grades in at least two segments in comparison with the initial exercise scintigram. Patients were followed up for 8 to 32 months (mean, 21 months); during this period, 37 patients had first cardiac events. Reversible ischemia was present in 29 patients on redistribution, of whom 14 (48%) had events; of 71 without reversible defects, 23 (32%) had events (hazard ratio, 1.5; 95% CI, 0.8 to 3.0; P=NS). Nitrate-enhanced rest 201Tl imaging detected reversible defects in 68 patients, of whom 33 (49%) had events, whereas of 32 without reversible defects, only 4 (13%) had subsequent cardiac events (hazard ratio, 8.1; 95% CI, 2.7 to 23.8; P<.001). CONCLUSIONS: Thus, after myocardial infarction and thrombolysis, even "stable" patients have a high (68%) incidence of viable but jeopardized myocardium, causing a high event rate. Those identified to be at high risk by perfusion imaging may benefit from early intervention.     

Influence of growth parameters on the dopant configuration of nitrogen-doped graphene synthesized from phthalocyanine molecules

Synthesis of nitrogen-doped graphene (NDG) via chemical vapor deposition (CVD) using phthalocyanine, a solid precursor containing carbon and nitrogen, is reported. The effect of the growth parameters (temperature, time, and carrier gas) on the surface morphology, dopant configuration, and conductivity of the films was studied. The NDG films were synthesized at different substrate temperatures of 1050 °C, 950 °C, and 850 °C for different growth times of 5–15 min in the presence of an Ar?+?H₂ gas mixture. Significantly, pyrrolic-N type defects are observed predominantly after 5 min of growth time. At 1050 °C, pyrrolic N content is around 45.4% after 5 min of growth which decreased to 24.1% after 15 min of growth, while the graphitic-N content increased from 41.2 to 76% at the same time. It is demonstrated that the conversion of pyrrolic type of nitrogen to graphitic nitrogen defects can be arrested by changing the carrier gas from Ar?+?H₂ to Ar. The pyrrolic-N content increased to 64% by changing the gas from Ar?+?H₂ to Ar at 15 min. The electrolyte gated field-effect transistors were fabricated using the obtained films, and dopant-dependent mobility was observed. The mobility for pyrrolic-N-dominated film is 13.6 cm² V^?1 s^?1 increasing to 62.8 cm² V^?1 s^?1 for graphitic-N-dominated film.