C-band superconductor/semiconductor hybrid field-effect transistor amplifier on a LaAlO3 substrate

A single-stage C-band superconductor/semiconductor hybrid field-effect transistor amplifier was designed, fabricated, and tested at 77 K. The large area (1 inch x 0.5 inches) high temperature superconducting Tl-Ba-Ca-Cu-O (TBCCO) thin film was rf magnetron sputtered onto a LaAlO3 substrate. The film had a transition temperature of about 92 K after it was patterned and etched. The amplifier showed a gain of 6 dB and a 3 dB bandwidth of 100 MHz centered at 7.9 GHz. An identical gold amplifier circuit was tested at 77 K, and these results are compared with those from the hybrid amplifier

Design Criteria for Fracture Assessment of Pressurized Nuclear Components

This paper presents the design criteria adopted for fracture assessment of pressurized components of nuclear power plants. Although there are wide variety of components in a typical nuclear power plant, the thrust in this paper is on components which are part of the primary heat transport system. The paper presents an overview of design rules, practices adopted and experimental verification needed for ensuring the structural integrity of nuclear pressure vessels and piping

Evolution of Efimov states into the continuum in neutron rich (2n-core) nuclei - A general study

The nuclear three-body system, with two halo neutrons very weakly coupled to a heavy core, is studied to investigate necessary conditions for the occurrence of Efimov states. Extending the analysis to the scattering sector, we find that these states evolve into Feshbach type resonances. This behaviour is very similar to the 20C nucleus in which the occurrence of Efimov states evolving into resonances in the elastic scattering of n?19C system has been investigated in recent publications. This work, thereby, extends the study of the Efimov effect beyond 20C, showing that 32Ne and 38Mg exhibit a very similar dynamical structure. These nuclei are, therefore, also candidates for probing experimentally the Efimov effect. © 2011 Elsevier B.V

Efimov states and their Fano resonances in a neutron-rich nucleus

Asymmetric resonances in elastic n+$^{19}$C scattering are attributed to Efimov states of such neutron-rich nuclei, that is, three-body bound states of the n+n+$^{18}$C system when none of the pairs is bound or some of them only weakly bound. By fitting to the general resonance shape described by Fano, we extract resonance position, width, and the "Fano profile index". While Efimov states have been discussed extensively in many areas of physics, there is only one very recent experimental observation in trimers of cesium atoms. The conjunction that we present of the Efimov and Fano phenomena may lead to experimental realization in nuclei.Comment: 4 double-column pages, 3 figure

Multiaxial fatigue studies on carbon steel piping material of Indian PHWRs

The tests studies and analyses have been carried out in the area of “Multiaxial Fatigue” with an objective to improve the damage assessment methodologies and design rules. Nearly 50 numbers of fatigue tests were conducted on solid and tubular specimens of SA333Gr.6 material under pure axial, pure shear and combined axial-torsion in-phase/ out-of-phase loading combinations. A software has been developed for the evaluation of multiaxial fatigue damage for the analyses of tests data using different invariant fatigue models such as ASME Sec.III code procedures, von-Mises etc. The fatigue crack initiation life was predicted using the best fit axial fatigue life curve (without use of safety factors). These tests and their analyses have helped in understanding the fatigue failure behavior of piping material under complex cyclic loadings where the principal directions rotate during a loading cycle. The crack initiation angles have also been measured by analyzing the image of the tested specimens. The measured crack angles will help in validation of the critical plane based models

Performance and modeling of superconducting ring resonators at millimeter-wave frequencies

Microstrip ring resonators operating at 35 GHz were fabricated from laser ablated YBCO thin films deposited on lanthanum aluminate substrates. They were measured over a range of temperatures and their performance compared to identical resonators made of evaporated gold. Below 60 Kelvin the superconducting strip performed better than the gold, reaching an unloaded Q approximately 1.5 times that of gold at 25 K. A shift in the resonant frequency follows the form predicted by the London equations. The Phenomenological Loss Equivalence Method is applied to the ring resonator and the theoretically calculated Q values are compared to the experimental results

Low cycle fatigue and cyclic plasticity bahaviour of Indian PHWR / AHWR primary piping materials

The integrity assessment of the primary piping components needs to be demonstrated under normal operation cyclic loadings as well as under complex cycling loadings of extreme magnitude as may come during a severe earthquake event. In order to understand material's cyclic plasticity and fatigue ratcheting behaviour, systematic experimental and analytical investigations have been carried out on specimens of SA333Gr.6 carbon steel and SS304LN stainless steel. The materials specification of SA333Gr.6 is same as used in Primary Heat transport (PHT) piping of Pressurized Heavy Water Reactors (PHWRs) and materials specification of SS304LN steel is same as proposed for Indian Advanced Heavy Water Recactor (AHWRs) Main Heat Transport (MHT) piping. The test program included the properties and cyclic plasticity behaviour. The results of these tests have been investigated in detals using few popular finite element cyclic plasticity models to understand and quantify the materials' cyclic plasticity behaviour. The studies revealed the need to modify the Chaboche model to simulate the LCF/cyclic plasticity and ratcheting under different stress/strain amplitude loading conditions. On accounting for modification, the Chaboche model nicely predicted the LCF and ratcheting response for all the tests. The tests, finite element analyses results and their interpretations have been presented in this paper

Fatigue studies on stainless steel piping materials and components: Indian AHWR

As a part of component integrity test program at Bhabha Atomic Research Centre, fatigue tests on full scale pipe and pipe welds were conducted in addition to CT and TPB specimens. In this paper the outcome of this program is discussed. Specimen testing was conducted to determine the basic cyclic stress strain curve, LCF and FCGR properties. FCGR tests were conducted on CT and TPB specimens to understand the effect of different conditions: Specimen level tests result show that, for the present grade of material, the FCGR is not significantly affected by specimen type (CT and TPB), specimen thickness and notch orientation. FCGR resistance of the hot wire GTAW is superior compared to that of conventional SMAW. The effects of stress ratio are mildly significant at lower R-values for base metal but are significant for weld metal. Component tests were conducted to understand the effect of the following variables:(a)Component type and size: pipe and pipe weld, Pipe diameters 170 mm and 324 mm,(b)Pipe and pipe weld: initial notch in pipe base, and girth welded pipe, (c) Pipe welds: Conventional GTAW/SMAW and hot wire narrow gap GTAW, (d)Environment: Air and water, (e) Type of loading: Constant amplitude cyclic, vibration, Block, overload and underload. Results indicated that the fatigue life of the component is reduced under water environment compared to air environment. Fatigue life of the pipe subjected to block loading (increasing stress ratio followed by decreasing stress ratio), intermittent overloading and underloading is also decreased compared to that of constant amplitude loading. Vibration loading reduces fatigue life significantly. Crack growth in thickness direction is more compared to circumferential direction for all types of loading which is desirable for demonstration of LBB criteria. Fatigue life of the notched component has also been predicted using the Paris constants data from the specimen level tests. Fatigue crack growth and the crack shape of the growing crack have been evaluated for regular interval of loading cycles. The predictions compares well with those of experiments

Reliability and Reproducibility of Landmark Identification in Unilateral Cleft Lip and Palate Patients: Digital Lateral Vis-A-Vis CBCT-Derived 3D Cephalograms

Background: The aim of the retrospective observational study was to compare the precision of landmark identification and its reproducibility using cone beam computed tomography-derived 3D cephalograms and digital lateral cephalograms in unilateral cleft lip and palate patients. Methods: Cephalograms of thirty-one (31) North Indian children (18 boys and 13 girls) with a unilateral cleft lip and palate, who were recommended for orthodontic treatment, were selected. After a thorough analysis of peer-reviewed articles, 20 difficult-to-trace landmarks were selected, and their reliability and reproducibility were studied. These were subjected to landmark identification to evaluate interobserver variability; the coordinates for each point were traced separately by three different orthodontists (OBA, OBB, OBC). Statistical analysis was performed using descriptive and inferential statistics with paired t-tests to compare the differences measured by the two methods. Real-scale data are presented in mean ± SD. A p-value less than 0.05 was considered as significant at a 95% confidence level. Results: When comparing, the plotting of points posterior nasal spine (PNS) (p < 0.05), anterior nasal spine (ANS) (p < 0.01), upper 1 root tip (p < 0.05), lower 1 root tip (p < 0.05), malare (p < 0.05), pyriforme (p < 0.05), porion (p < 0.01), and basion (p < 0.05) was statistically significant. Conclusion: In patients with a cleft lip and palate, the interobserver identification of cephalometric landmarks was significantly more precise and reproducible with cone beam computed tomography -derived cephalograms vis-a-vis digital lateral cephalograms

Prevalence of high - risk human papillomavirus infections in women with benign cervical cytology: A hospital based study from North India

INTRODUCTION: Cervical cancer is the commonest cancer among Indian women. High-risk human papillomavirus (HPV) detection holds the potential to be used as a tool to identify women, at risk for subsequent development of cervical cancer. There is a pressing need for identifying prevalence of asymptomatic cervical HPV infection in the local population. OBJECTIVE: To determine the prevalence of high-risk HPV DNA in women with benign cervical cytology. MATERIALS AND METHODS: Women visiting the gynecology outpatient with varied complaints were subjected to Pap smear. Four hundred and seventy two samples were subjected to polymerase chain reaction, using consensus primers for low and high-risk HPV (types 6, 11, 16, 18, 31 and 33). The samples that were positive for HPV DNA were subsequently assessed for high-risk consensus primers, types 16, 18, 31 and 33 as well as for HPV type 16 and 18. RESULTS: One hundred and seventy four (36.8%) women tested positive for HPV DNA. Thirty nine (8.2%) of the entire cohort tested positive for high-risk HPV. Fifteen samples were positive for type 16, 22 for type 18 and two for both types 16 and 18. A statistically higher prevalence of high-risk HPV was observed in poorly educated and rural groups. No association of HPV prevalence was noted with age, parity and age at marriage. CONCLUSION: The study generates epidemiological data of prevalence of sub-clinical HPV in the women visiting a tertiary care institute as well as peripheral health centres. The data generated will be useful for laying guidelines for mass screening of HPV, treatment and prophylaxis in the local population