High Temperature Deformation Behavior of in-situ Bulk Metallic Glass Matrix Composites

Macroscopic ductility is promoted in bulk metallic glasses by both composite reinforcements (at low temperatures) and by the activation of viscous flow mechanisms (at high temperatures). It is of fundamental interest to understand deformation physics when both of these strategies are employed at the same time. Despite the quickly growing literature around the room-temperature mechanical properties of metallic glass matrix composites (MGMCs), the deformation behavior of MGMCs over a wide range of temperatures and strain rates has yet to be systematically investigated, especially at high temperatures close to Tg. Here the high temperature compressive behavior of Zr-based MGMCs with in-situ reinforcements is explored systematically over a series of strain rates. Additionally, the volume fraction of second-phase reinforcements was tailored to explore its effect on both inhomogeneous and homogeneous deformation modes.Singapore-MIT Alliance (SMA

High Temperature Deformation Behavior of Bulk Metallic Glass and Its Composites

The homogeneous deformation of Zr-based bulk metallic glass composites is studied near the glass transition temperature, at various levels of reinforcement volume fraction. Through examination of the constitutive response, it is seen that the presence of in-situ reinforcements increases the flow resistance of the glass dramatically. This strengthening effect is shown to arise from two separate contributions: load transfer from the amorphous matrix to the reinforcements, and changes to the glass composition and structure upon in-situ precipitation of reinforcements.Singapore-MIT Alliance (SMA

Microwave characteristics of liquid-crystal tunable capacitors

[[abstract]]This letter investigates the microwave characteristics of the liquid crystal tunable capacitors for the first time. With the dielectric anisotropy properties, the liquid crystal capacitors present very different characteristics compared to the semiconductor or MEMS tunable capacitors. A quality factor of 310 with a control voltage of 5 V was achieved at 4 GHz. A tuning range of 25.3% for the control voltages from 0 to 5 V was obtained at 5 GHz. The results demonstrate the potential applications of liquid crystals as dielectric materials for capacitors with high quality factors and wide tuning ranges at high frequencies, particularly suitable for the future flexible electronics with transparent substrates.[[fileno]]2030121010007[[department]]電機工程學

Creating Bell states and decoherence effects in quantum dots system

We show how to improve the efficiency for preparing Bell states in coupled two quantum dots system. A measurement to the state of driven quantum laser field leads to wave function collapse. This results in highly efficiency preparation of Bell states. The effect of decoherence on the efficiency of generating Bell states is also discussed in this paper. The results show that the decoherence does not affect the relative weight of $|00>$ and $|11>$ in the output state, but the efficiency of finding Bell states.Comment: 4 pages, 2figures, corrected some typo

Comparison of the validity of smear and culture conversion as a prognostic marker of treatment outcome in patients with multidrug-resistant tuberculosis

Background The World Health Organization (WHO) has conditionally recommended the use of sputum smear microscopy and culture examination for the monitoring of multidrug-resistant tuberculosis (MDR-TB) treatment. We aimed to assess and compare the validity of smear and culture conversion at different time points during treatment for MDR-TB, as a prognostic marker for end-of-treatment outcomes. Methods We undertook a retrospective observational cohort study using data obtained from Hunan Chest Hospital, China and Gondar University Hospital, Ethiopia. The sensitivity and specificity of culture and sputum smear conversion for predicting treatment outcomes were analysed using a random-effects generalized linear mixed model. Results A total of 429 bacteriologically confirmed MDR-TB patients with a culture and smear positive result were included. Overall, 345 (80%) patients had a successful treatment outcome, and 84 (20%) patients had poor treatment outcomes. The sensitivity of smear and culture conversion to predict a successful treatment outcome were: 77.9% and 68.9% at 2 months after starting treatment (difference between tests, p = 0.007); 95.9% and 92.7% at 4 months (p = 0.06); 97.4% and 96.2% at 6 months (p = 0.386); and 99.4% and 98.9% at 12 months (p = 0.412), respectively. The specificity of smear and culture non-conversion to predict a poor treatment outcome were: 41.6% and 60.7% at 2 months (p = 0.012); 23.8% and 48.8% at 4 months (p<0.001); and 20.2% and 42.8% at 6 months (p<0.001); and 15.4% and 32.1% (p<0.001) at 12 months, respectively. The sensitivity of culture and smear conversion increased as the month of conversion increased but at the cost of decreased specificity. The optimum time points after conversion to provide the best prognostic marker of a successful treatment outcome were between two and four months after treatment commencement for smear, and between four and six months for culture. The common optimum time point for smear and culture conversion was four months. At this time point, culture conversion (AUROC curve = 0.71) was significantly better than smear conversion (AUROC curve = 0.6) in predicting successful treatment outcomes (p < 0.001). However, the validity of smear conversion (AUROC curve = 0.7) was equivalent to culture conversion (AUROC curve = 0.71) in predicting treatment outcomes when demographic and clinical factors were included in the model. The positive and negative predictive values for smear conversion were: 57.3% and 65.7% at two months, 55.7% and 85.4% at four months, and 55.0% and 88.6% at six months; and for culture conversions it was: 63.7% and 66.2% at two months, 64.4% and 87.1% at four months, and 62.7% and 91.9% at six months, respectively. Conclusions The validity of smear conversion is significantly lower than culture conversion in predicting MDR-TB treatment outcomes. We support the WHO recommendation of using both smear and culture examination rather than smear alone for the monitoring of MDR-TB patients for a better prediction of successful treatment outcomes. The optimum time points to predict a future successful treatment outcome were between two and four months after treatment commencement for sputum smear conversion and between four and six months for culture conversion. The common optimum times for culture and smear conversion together was four months

Quantum logic between atoms inside a high Q optical cavity

We propose a protocol for conditional quantum logic between two 4-state atoms inside a high Q optical cavity. The process detailed in this paper utilizes a direct 4-photon 2-atom resonant process and has the added advantage of commonly addressing the two atoms when they are inside the high Q optical cavity.Comment: 8 pages, 3 figs. submitte

Fabrication of high quality plan-view TEM specimens using the focused ion beam

We describe a technique using a focused ion beam instrument to fabricate high quality plan-view specimens for transmission electron microscopy studies. The technique is simple, site-specific and is capable of fabricating multiple large, &gt;100 μm2 electron transparent windows within epitaxially-grown thin films. A film of La0.67Sr0.33MnO3 is used to demonstrate the technique and its structural and functional properties are surveyed by high resolution imaging, electron spectroscopy, atomic force microscopy and Lorentz electron microscopy. The window is demonstrated to have good thickness uniformity and a low defect density that does not impair the film’s Curie temperature. The technique will enable the study of in–plane structural and functional properties of a variety of epitaxial thin film systems

Energy levels and far-infrared spectroscopy for two electrons in a semiconductor nanoring

The effects of electron-electron interaction of a two-electron nanoring on the energy levels and far-infrared (FIR) spectroscopy have been investigated based on a model calculation which is performed within the exactly numerical diagonalization. It is found that the interaction changes the energy spectra dramatically, and also shows significant influence on the FIR spectroscopy. The crossings between the lowest spin-singlet and triplet states induced by the coulomb interaction are clearly revealed. Our results are related to the experiment recently carried out by A. Lorke et al. [Phys. Rev. Lett. 84, 2223 (2000)].Comment: 17 pages, 6 figures, revised and accepted by Phys. Rev. B (Dec. 15

Metropolis simulations of Met-Enkephalin with solvent-accessible area parameterizations

We investigate the solvent-accessible area method by means of Metropolis simulations of the brain peptide Met-Enkephalin at 300$K$. For the energy function ECEPP/2 nine atomic solvation parameter (ASP) sets are studied. The simulations are compared with one another, with simulations with a distance dependent electrostatic permittivity $\epsilon (r)$, and with vacuum simulations ($\epsilon =2$). Parallel tempering and the biased Metropolis techniques RM$_1$ are employed and their performance is evaluated. The measured observables include energy and dihedral probability densities (pds), integrated autocorrelation times, and acceptance rates. Two of the ASP sets turn out to be unsuitable for these simulations. For all other systems selected configurations are minimized in search of the global energy minima, which are found for the vacuum and the $\epsilon(r)$ system, but for none of the ASP models. Other observables show a remarkable dependence on the ASPs. In particular, we find three ASP sets for which the autocorrelations at 300$$K are considerably smaller than for vacuum simulations.Comment: 10 pages and 8 figure

YREC: The Yale Rotating Stellar Evolution Code

The stellar evolution code YREC is outlined with emphasis on its applications to helio- and asteroseismology. The procedure for calculating calibrated solar and stellar models is described. Other features of the code such as a non-local treatment of convective core overshoot, and the implementation of a parametrized description of turbulence in stellar models, are considered in some detail. The code has been extensively used for other astrophysical applications, some of which are briefly mentioned at the end of the paper.Comment: 10 pages, 2 figures, ApSS accepte