Thermoelectric properties of Al-doped mesoporous ZnO thin films

Al-doped mesoporous ZnO thin films were synthesized by a sol-gel process and an evaporation-induced self-assembly process. In this work, the effects of Al doping concentration on the electrical conductivity and characterization of mesoporous ZnO thin films were investigated. By changing the Al doping concentration, ZnO grain growth is inhibited, and the mesoporous structure of ZnO is maintained during a relatively high temperature annealing process. The porosity of Al-doped mesoporous ZnO thin films increased slightly with increasing Al doping concentration. Finally, as electrical conductivity was increased as electrons were freed and pore structure was maintained by inhibiting grain growth, the thermoelectric property was enhanced with increasing Al concentration. © 2013 Min-Hee Hong et al

Effect of surfactant concentration variation on the thermoelectric properties of mesoporous ZnO

The electrical and thermal conductivities and the Seebeck coefficient of mesoporous ZnO thin films were investigated to determine the change of their thermoelectric properties by controlling surfactant concentration in the mesoporous ZnO films, because the thermoelectric properties of mesoporous ZnO films can be influenced by the porosity of the mesoporous structures, which is primarily determined by surfactant concentration in the films. Mesoporous ZnO thin films were successfully synthesized by using sol-gel and evaporation-induced self-assembly processes. Zinc acetate dihydrate and Brij-76 were used as the starting material and pore structure-forming template, respectively. The porosity of mesoporous ZnO thin films increased from 29% to 40% with increasing surfactant molar ratio. Porosity can be easily altered by controlling the molar ratio of surfactant/precursor. The electrical and thermal conductivity and Seebeck coefficients showed a close correlation with the porosity of the films, indicating that the thermoelectric properties of thin films can be changed by altering their porosity. Mesoporous ZnO thin films with the highest porosity had the best thermoelectric properties (the lowest thermal conductivity and the highest Seebeck coefficient) of the films examined. © 2013 Min-Hee Hong et al

A Similarity Measure for GPU Kernel Subgraph Matching

Accelerator architectures specialize in executing SIMD (single instruction, multiple data) in lockstep. Because the majority of CUDA applications are parallelized loops, control flow information can provide an in-depth characterization of a kernel. CUDAflow is a tool that statically separates CUDA binaries into basic block regions and dynamically measures instruction and basic block frequencies. CUDAflow captures this information in a control flow graph (CFG) and performs subgraph matching across various kernel's CFGs to gain insights to an application's resource requirements, based on the shape and traversal of the graph, instruction operations executed and registers allocated, among other information. The utility of CUDAflow is demonstrated with SHOC and Rodinia application case studies on a variety of GPU architectures, revealing novel thread divergence characteristics that facilitates end users, autotuners and compilers in generating high performing code

ELASTOGRAPHY CAN EFFECTIVELY DECREASE THE NUMBER OF FINE-NEEDLE ASPIRATION BIOPSIES IN PATIENTS WITH CALCIFIED THYROID NODULES

When calcification, frequently found in both benign and malignant nodules, is present in thyroid nodules, non-invasive differentiation with ultrasound becomes challenging. The goal of this study was to evaluate the utility of elastography in differentiating calcified thyroid nodules. Consecutive patients (165 patients with 196 nodules) referred for fine-needle aspiration who had undergone both ultrasound elastography and B-mode examinations were analyzed retrospectively. Calcification was present in 45 benign and 20 malignant nodules. On 65 calcified nodules, elastography had 95% sensitivity, 51.1% specificity, 46.3% positive predictive value and 95.8% negative predictive value in detecting malignancy. Twenty-three of 45 benign calcified nodules were correctly diagnosed with elastography compared with 4 of 45 by B-mode ultrasound. Although it is difficult to differentiate benign and malignant calcified thyroid nodules solely with B-mode ultrasound, elastography has the potential to reduce the number of fine-needle aspiration biopsies performed on calcified nodules. (C) 2014 World Federation for Ultrasound in Medicine & Biology.1188Ysciescopu

Laser Cooling of Optically Trapped Molecules

Calcium monofluoride (CaF) molecules are loaded into an optical dipole trap (ODT) and subsequently laser cooled within the trap. Starting with magneto-optical trapping, we sub-Doppler cool CaF and then load $150(30)$ CaF molecules into an ODT. Enhanced loading by a factor of five is obtained when sub-Doppler cooling light and trapping light are on simultaneously. For trapped molecules, we directly observe efficient sub-Doppler cooling to a temperature of $60(5)$ $\mu\text{K}$. The trapped molecular density of $8(2)\times10^7$ cm$^{-3}$ is an order of magnitude greater than in the initial sub-Doppler cooled sample. The trap lifetime of 750(40) ms is dominated by background gas collisions.Comment: 5 pages, 5 figure

Atomic-scale combination of germanium-zinc nanofibers for structural and electrochemical evolution

Alloys are recently receiving considerable attention in the community of rechargeable batteries as possible alternatives to carbonaceous negative electrodes; however, challenges remain for the practical utilization of these materials. Herein, we report the synthesis of germanium-zinc alloy nanofibers through electrospinning and a subsequent calcination step. Evidenced by in situ transmission electron microscopy and electrochemical impedance spectroscopy characterizations, this one-dimensional design possesses unique structures. Both germanium and zinc atoms are homogenously distributed allowing for outstanding electronic conductivity and high available capacity for lithium storage. The as-prepared materials present high rate capability (capacity of similar to 50% at 20 C compared to that at 0.2 C-rate) and cycle retention (73% at 3.0 C-rate) with a retaining capacity of 546 mAh g(-1) even after 1000 cycles. When assembled in a full cell, high energy density can be maintained during 400 cycles, which indicates that the current material has the potential to be used in a large-scale energy storage system

Towards quantum computing with single atoms and optical cavities on atom chips

We report on recent developments in the integration of optical microresonators into atom chips and describe some fabrication and implementation challenges. We also review theoretical proposals for quantum computing with single atoms based on the observation of photons leaking through the cavity mirrors. The use of measurements to generate entanglement can result in simpler, more robust and scalable quantum computing architectures. Indeed, we show that quantum computing with atom-cavity systems is feasible even in the presence of relatively large spontaneous decay rates and finite photon detector efficiencies.Comment: 14 pages, 6 figure

Evolutionary Toggling of Vpx/Vpr Specificity Results in Divergent Recognition of the Restriction Factor SAMHD1

SAMHD1 is a host restriction factor that blocks the ability of lentiviruses such as HIV-1 to undergo reverse transcription in myeloid cells and resting T-cells. This restriction is alleviated by expression of the lentiviral accessory proteins Vpx and Vpr (Vpx/Vpr), which target SAMHD1 for proteasome-mediated degradation. However, the precise determinants within SAMHD1 for recognition by Vpx/Vpr remain unclear. Here we show that evolution of Vpx/Vpr in primate lentiviruses has caused the interface between SAMHD1 and Vpx/Vpr to alter during primate lentiviral evolution. Using multiple HIV-2 and SIV Vpx proteins, we show that Vpx from the HIV-2 and SIVmac lineage, but not Vpx from the SIVmnd2 and SIVrcm lineage, require the C-terminus of SAMHD1 for interaction, ubiquitylation, and degradation. On the other hand, the N-terminus of SAMHD1 governs interactions with Vpx from SIVmnd2 and SIVrcm, but has little effect on Vpx from HIV-2 and SIVmac. Furthermore, we show here that this difference in SAMHD1 recognition is evolutionarily dynamic, with the importance of the N- and C-terminus for interaction of SAMHD1 with Vpx and Vpr toggling during lentiviral evolution. We present a model to explain how the head-to-tail conformation of SAMHD1 proteins favors toggling of the interaction sites by Vpx/Vpr during this virus-host arms race. Such drastic functional divergence within a lentiviral protein highlights a novel plasticity in the evolutionary dynamics of viral antagonists for restriction factors during lentiviral adaptation to its hosts. © 2013 Fregoso et al