Dihydrolipoic Acid Induces Cytotoxicity in Mouse Blastocysts through Apoptosis Processes

α-Lipoic acid (LA) is a thiol with antioxidant properties that protects against oxidative stress-induced apoptosis. LA is absorbed from the diet, taken up by cells and tissues, and subsequently reduced to dihydrolipoic acid (DHLA). In view of the recent application of DHLA as a hydrophilic nanomaterial preparation, determination of its biosafety profile is essential. In the current study, we examined the cytotoxic effects of DHLA on mouse embryos at the blastocyst stage, subsequent embryonic attachment and outgrowth in vitro, in vivo implantation by embryo transfer, and early embryonic development in an animal model. Blastocysts treated with 50 μM DHLA exhibited significantly increased apoptosis and a corresponding decrease in total cell number. Notably, the implantation success rates of blastocysts pretreated with DHLA were lower than that of their control counterparts. Moreover, in vitro treatment with 50 μM DHLA was associated with increased resorption of post-implantation embryos and decreased fetal weight. Data obtained using an in vivo mouse model further disclosed that consumption of drinking water containing 100 μM DHLA led to decreased early embryo development, specifically, inhibition of development to the blastocyst stage. However, it appears that concentrations of DHLA lower than 50 μM do not exert a hazardous effect on embryonic development. Our results collectively indicate that in vitro and in vivo exposure to concentrations of DHLA higher than 50 μM DHLA induces apoptosis and retards early pre- and post-implantation development, and support the potential of DHLA to induce embryonic cytotoxicity.     

A planarized shallow-trench-isolation for GaAs devices fabricationusing liquid phase chemical enhanced oxidation process

A new planarized trench isolation technique for GaAs devices fabrication by a liquid phase chemical-enhanced oxidation (LPCEO) method is proposed. The LPCEO-trench-isolation technique can be operated at low temperature with a simple and low-cost process. As compared with conventional mesa isolation, the LPCEO-trench-isolation can provide better planarity and isolation properties. Finally, GaAs MOSFETs fabricated with LPCEO-trench-isolation and selective oxidized gate both by the LPCEO method are demonstrated     

Titanium nitride as spreading layers for AlGaInP visible LEDs

Thin titanium nitride (TiN) films with low sheet resistance and high transparency were deposited on AlGaInP light-emitting diodes (LEDs) to improve light extraction from the LED surface. Comparison test devices were fabricated both with and without TiN spreading layers. Results show LED current crowding at high current is reduced for devices with TiN current spreading film, improving external efficiency. It is confirmed that TiN films are feasible as current spreading layers of AlGaInP LEDs.     

A novel Al and Y codoped ZnO/n-Si heterojunction solar cells fabricated by pulsed laser deposition

Al and Y codoped ZnO (AZOY) transparent conducting oxide (TCO) thin films were first deposited on n-Si substrates by pulsed laser deposition (PLD) to form AZOY/n-Si heterojunction solar cells. However, the properties of the AZOY emitter layers are critical to the performance of AZOY/n-Si heterojunction solar cells. To estimate the properties of AZOY thin films, films deposited on glass substrates with various substrate temperatures (T_s) were analyzed. Based on the experimental results, optimal electrical properties (resistivity of 2.8 ± 0.14 × 10^?4 Ω cm, carrier mobility of 27.5 ± 0.55 cm²/Vs, and carrier concentration of 8.0 ± 0.24 × 10²⁰ cm^?3) of the AZOY thin films can be achieved at a T_s of 400 °C, and a high optical transmittance of AZOY is estimated to be >80% (with glass substrate) in the visible region under the same T_s. For the AZOY/n-Si heterojunction solar cells, the AZOY thin films acted not only as an emitter layer material, but also as an anti-reflected coating thin film. Thus, a notably high short-circuit current density (J_sc) of 31.51 ± 0.186 mA/cm² was achieved for the AZOY/n-Si heterojunction solar cells. Under an AM1.5 illumination condition, the conversion efficiency of the cells is estimated at only approximately 4% (a very low open-circuit voltage (V_oc) of 0.24 ± 0.001 V and a fill factor (FF) of 0.51 ± 0.011) without any optimization of the device structure.     

Near 10 μm intervalence subband optical transitions in p-type In0.49Ga0.51P-GaAs quantum well structures

In this paper, the intervalence subband optical transitions in p-doped In_0.49Ga_0.51P-GaAs quantum well structures are theoretically investigated. The intervalence subband optical transitions are modelled by the multiband effective mass equations incorporating the unitary transformation numerical method. The present formalism is based on the k&oarr;·P&oarr; perturbation theory as done to date but contains two significant improvements: 1) a more efficient treatment of band structures, optical matrix elements, and absorption coefficients; and 2) the avoidance of zero-order Bloch function approximation for calculating the intervalence subband optical matrix elements and absorption spectra in favour of correcting the first-order perturbation theory in order to take the remote band effects into account. Both of the requirements, especially the latter, play a very important role in gaining qualitative insight and obtaining quantitative calculation of optical selection rules. A systematical study of the subband structures, intervalence subband optical matrix elements, and absorption spectra is made for p-doped In_0.49Ga _0.51P-GaAs quantum wells, and a design guideline for near 10 μm infrared absorption is also discussed     

Continuously tunable photopumped 1.3-μm fiber Fabry-Perotsurface-emitting lasers

Continuously tunable, single-frequency, optically pumped semiconductor-fiber lasers are demonstrated that embody a half-cavity, vertical-cavity surface-emitting laser within a fiber Fabry-Perot cavity. Continuous wavelength tuning over 40 nm at 1300-nm wavelength region is obtained under continuous-wave operation     

Plasma-induced TCO texture of ZnO:Ga back contacts on silicon thin film solar cells

This paper considers texturing of ZnO:Ga (GZO) films used as back contacts in amorphous silicon (a-Si) thin film solar cells. GZO thin films are first prepared by conventional methods. The as-deposited GZO surface properties are modified so that their use as back contacts on a-Si solar cells is enhanced. Texturing is performed by simple dry plasma etching in a CVD process chamber,at power=100 W, substrate temperature=190 °C (temperature is held at 190 °C because thin film solar cells are damaged above 200 °C), pressure=400 Pa and process gas H₂ flow=700 sccm. Conventional a-Si solar cells are fabricated with and without GZO back contact surface treatment. Comparison of the with/without texturing GZO films shows that plasma etching increases optical scattering reflectance and reflection haze. SEM and TEM are used to evaluate the morphological treatment-induced changes in the films. Comparison of the a-Si solar cells with/without texturing shows that the plasma treatment increases both the short-circuit current density and fill factor. Consequently, a-Si solar cell efficiency is relatively improved by 4.6%.     

Spurious suppression of a microstrip bandpass filter using three types of rectangular PBG loops.

A novel microstrip bandpass filter with three types of rectangular, photonic bandgap (PBG) loops on a middle layer was designed and demonstrated using a full-wave electromagnetic (EM) simulator, with the predicted results verified by experiment. This investigation presents the configurations of conventional parallel-coupled 2 GHz filters with and without a PBG. The middle-layer of PBG loops adds an extra stopband-rejection mode to filter stopband; and it provides attenuation in excess of 25 dB at the second, third, and fourth harmonics, thus demonstrating that superior stopband characteristics at high frequency can be obtained using the proposed PBG loops in microwave filters.     

A single-supply Ku-band 1-W power amplifier MMIC with compact self-bias PHEMTs

In this letter, the design of a self-bias 1.8-mm AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor with a compact source capacitor for operation in Ku-band frequency is described. Based on the proposed device, a self-bias Ku-band 1-W two-stage power amplifier monolithic microwave integrated circuit (MMIC) is also demonstrated. Under a single bias condition of 8 V and 630 mA, the self-bias MMIC possesses 14.2-dB small-signal gain, 30.2-dBm output power at 1-dB gain compression point with 19.2% power added efficiency and 31.3-dBm saturated output power with 22.5% power added efficiency at 14GHz. With the performance comparable to the dual-bias MMIC counterpart, the proposed self-bias MMIC is more attractive to system designers on very small aperture terminal applications.