Control over topological insulator photocurrents with light polarization

Three-dimensional topological insulators represent a new quantum phase of matter with spin-polarized surface states that are protected from backscattering. The static electronic properties of these surface states have been comprehensively imaged by both photoemission and tunnelling spectroscopies. Theorists have proposed that topological surface states can also exhibit novel electronic responses to light, such as topological quantum phase transitions and spin-polarized electrical currents. However, the effects of optically driving a topological insulator out of equilibrium have remained largely unexplored experimentally, and no photocurrents have been measured. Here, we show that illuminating the topological insulator Bi(2)Se(3) with circularly polarized light generates a photocurrent that originates from topological helical Dirac fermions, and that reversing the helicity of the light reverses the direction of the photocurrent. We also observe a photocurrent that is controlled by the linear polarization of light and argue that it may also have a topological surface state origin. This approach may allow the probing of dynamic properties of topological insulators and lead to novel opto-spintronic devices.     

A 0.6 V Low-Power Wide-Range Delay-Locked Loop in 0.18 $mu$m CMOS

In this letter, a delay-locked loop (DLL) suitable for low-power and low-voltage operations is presented. To overcome the performance limitations, such as a restricted locking range and elevated output jitters, a novel voltage-controlled delay cell and a phase/frequency detector with a start controller are employed in the proposed DLL. Using a standard 0.18 mum CMOS process, the fabricated circuit exhibits a locking range from 85 to 550 MHz. The measured peak-to-peak and rms jitters at 550 MHz are 25.6 and 3.8 ps, respectively. Operated at a supply voltage of 0.6 V, the power consumption of the DLL circuit varies from 2.4 to 4.2 mW within the entire locking range.     

A 10 GHz Phase-Locked Loop With a Compact Low-Pass Filter in 0.18 $mu$ m CMOS

In this letter, a multi-gigahertz phase-locked loop (PLL) with a compact low-pass filter is presented. By using a novel dual-path control in the PLL architecture, the capacitance in the loop filter can be effectively reduced for high-level integration while maintaining the required loop bandwidth. Consequently, the noise resulted from off-chip components is therefore eliminated, leading to lower timing jitter at the PLL output waveforms. In addition, the timing jitter is further suppressed due to the use of decomposed phase and frequency detection. Based on the proposed techniques, a 10 GHz PLL is implemented in 0.18 mum CMOS for demonstration. Consuming a dc power of 113 mW from a 1.8 V supply, the fabricated circuit exhibits a locking range from 10.1 to 11 GHz. At an output frequency of 10.3 GHz, the measured peak-to-peak and rms jitter are 3.78 and 0.44 ps, respectively.     

A new ambipolar blue emitter for NTSC standard blue organic light-emitting device

A novel blue emitter, In2Bt, featured with a rigid and coplanar distyryl-p-phenylene backbone flattened by two different bridging atoms (i.e. carbon and sulfur) exhibits high thermal and morphological stability (T_g ～ 192 °C) and ambipolar charge carrier mobilities in the range of 10^?4 ～ 10^?5 cm² V^?1 s^?1. OLED device: ITO/PEDOT:PSS (300 Å)/α-NPD (200 Å)/TCTA (100 Å)/In2Bt (200 Å)/TPBI (500 Å)/LiF (5 Å)/Al (1500 Å) utilized In2Bt as an emitter gave a maximum brightness as high as 8000 cd m^?2 (12 V) and saturated-blue emission with CIE chromaticity coordinates of (0.16, 0.08), which is very close to the National Television Standards Committee (NTSC) standard blue gives an enlarged palette of colors for color displays.     

Effect of Thawing and Cold Storage on Frozen Chicken Thigh Meat Quality by High-Voltage Electrostatic Field

ABSTRACT: One of the most popular issues in electrostatic biology is the effects of a high-voltage electrostatic field (HVEF) on the thawing of chicken thigh meat. In this study, chicken thigh meat was treated with HVEF (E-group), and compared to samples stored in a common refrigerator (R-group), to investigate how HVEF affects chicken thigh meat quality after thawing at low temperature storage (−3 and 4 °C). The results showed that there were no significant differences in biochemical and microorganism indices at −3 °C. However, the HVEF can significantly shorten thawing time for frozen chicken thigh meat at −3 °C. After thawing chicken thigh meat and storing at 4 °C, the total viable counts reached the Intl. Commission on Microbiological Specification for Foods limit of 10⁷ CFU/g on the 6 and 8 d for the R- and E-group, respectively. On the 8th d, the volatile basic nitrogen had increased from 11.24 mg/100 g to 21.9 mg/100 g for the E-group and 39.9 mg/100 g for the R-group, respectively. The biochemical and microorganism indices also indicated that the E-group treatment yielded better results on thawing than the R-group treatment. The application of this model has the potential to keep products fresh.     

Mutagenicity and antimutagenic effect of soymilk fermented with lactic acid bacteria and bifidobacteria

In this study, soymilk was first fermented with lactic acid bacteria (Streptococcus thermophilus, Lactobacillus acidophilus) and bifidobacteria (Bifidobacterium infantis, Bifidobacterium longum) both individually and simultaneously. Mutagenicity and the suppression of fermented soymilk against the mutagenesis induced by 4-nitroquinoline-N-oxide (4-NQO), a direct-acting mutagen, and 3,2'-dimethyl-4-amino-biphenyl (DMAB), an indirect-acting mutagen, on Salmonella typhimurium TA 100, was then investigated. It was found that the fermented soymilk shows no mutagenic activity on Sal. typhimurium TA 100. Fermentation, in general, significantly (p<0.05) enhanced the antimutagenicity of soymilk. The levels of increased antimutagenicity of fermented soymilk varied with the starter organism and the type of mutagen tested. Although unfermented soymilk exerted lower antimutagenic activity against DMAB than 4-NQO, the fermented soymilk, generally, showed a higher antimutagenic activity against DMAB than 4-NQO. Among the various fermented soymilk tested, soymilk fermented with both Str. themophilus and B. infantis simultaneously exhibited the highest antimutagenicity of 85.07% and 85.78%, respectively, against 4-NQO and DMAB Further investigation on this fermented soymilk revealed that both the antimutagenic factors formed during fermentation and the cells of the starter organisms contributed to the increased antimutagenic activity against DMAB, while the former led to the increased activity against 4-NQO.     

Simulation and Verification of Two-Dimensional Ohmic Heating in Static System

Temperature distribution in a two-dimensional electrical heated system was determined both by computer simulation and experimental measurement. A commercial software program package was used for simulation. The experiment was conducted in a system where the vertical dimension was minimal to minimize natural convection during ohmic heating. In a rectangular static system containing a rectangular particle, computer simulation showed a trend verified by similar experimental results. Heat loss to the environment and physical property values used in simulation were major factors affecting differences between experimental and simulation results. There was no evidence for the presence of any coldest spot other than at the center of particles.     

Reasons for discontinuing intracavernous injection therapy with prostaglandin E1 (alprostadil)

OBJECTIVES: To clarify the reasons why experience with self-injection therapy for erectile dysfunction shows high dropout rates. METHODS:We studied 86 patients 36 to 76 years old who had been on home treatment for at least 3 months. Sixty-nine patients (80%) were continuing to use injections, and 17 (20%) had discontinued the treatment. Patients were evaluated by interview and clinical examination. RESULTS: Patients still in the program used one injection every 2 weeks, and those who had given up treatment had used one injection in 3 weeks (P = 0.31). They were in the program for 39+/-27 and 16+/-22 months (P = 0.002), respectively, and had used 50 (95% confidence interval [CI] 21 to 91) versus 12 (95% CI 4 to 20) injections, respectively (P<0.0001). Injections producing unsatisfactory penile rigidity, prolonged erections, hematoma at injection site, corporal fibrosis, secondary penile deviation, and mean estimated duration of a pharmacoinduced erection showed no significant differences. Patient satisfaction (P = 0.02), estimated partner satisfaction (P = 0.02), increase in self-esteem (P = 0.01), and negligible effort in performing injections (P = 0.001) all showed significantly better results for those still in the program. CONCLUSIONS: Reasons for dropout from self-injection therapy are not based on objective side effects and discomfort. Patients leaving the program are less motivated, less satisfied with the quality of pharmacoinduced sexuality, consider the effort to perform injections to be substantial, and have not achieved improved self-esteem.     

Deposition and super liquid repellency of fluorinated ZnO nanoparticles on carbon fabrics

The liquid-repellent behavior of fluorinated zinc oxide (ZnO) nanoparticles deposited onto carbon fabric (CF) by a pulse microwave-assisted (MA) method followed by surface fluorination treatment was investigated. The MA process is performed at 80 °C within 10 min with different pH values of 5.5, 8 and 12. The hexagonal ZnO nanoparticles with an average size of 100 nm exhibit a well-defined wurtzite crystal structure without any heat treatment. The ZnO nanoparticles produced by MA synthesis at pH = 8 display the maximal density over CF substrate. The fluorination coating effectively imparts super water and oil repellencies on the ZnO–CF surface; i.e., the contact angles are 163° (water) and 153° (ethylene glycol, EG). The liquid repellencies toward water and EG droplets show an increasing function of surface density of ZnO nanoparticles. This result can be attributed to the fact that an air layer is confined in the nanoparticles, thereby inducing a rougher gas–vapor–solid contact line, referred to as the Cassie state. Based on the Young–Duprè equation incorporated with the Cassie parameter, the lowest work of adhesion (W_ad) values of the ZnO–CF surface for water and EG repellencies are estimated to be 3.16 and 4.93 mJ/m², respectively. Accordingly, this work sheds some light on the creation of a two-tier texture by an efficient MA route and on how the surface density of ZnO nanoparticles strongly affects the repellent behavior of the resultant ZnO–CF composites.     

An auto-I/Q calibrated CMOS transceiver for 802.11g

The CMOS transceiver IC exploits the superheterodyne architecture to implement a low-cost RF front-end with an auto-I/Q calibration function for IEEE 802.11g. The transceiver supports I/Q gain and phase mismatch auto tuning mechanisms at both the transmitting and receiving ends, which are able to reduce the phase mismatch to within 1/spl deg/ and gain mismatch to 0.1dB. Implemented in a 0.25 /spl mu/m CMOS process with 2.7 V supply voltage, the transceiver delivers a 5.1 dB receiver cascade noise figure, 7 dBm transmit, and a 1 dB compression point.