Enhancing carrier transport and carrier capture with a good current spreading characteristic via graphene transparent conductive electrodes in InGaN/GaN multiple-quantum-well light emitting diodes.

In this work, InGaN/GaN multiple-quantum-wells light-emitting diodes with and without graphene transparent conductive electrodes are studied with current-voltage, electroluminescence, and time-resolved electroluminescence (TREL) measurements. The results demonstrate that the applications of graphene electrodes on LED devices will spread injection carriers more uniformly into the active region and therefore result in a larger current density, broader luminescence area, and stronger EL intensity. In addition, the TREL data will be further analyzed by employing a 2-N theoretical model of carrier transport, capture, and escape processes. The combined experimental and theoretical results clearly indicate that those LEDs with graphene transparent conductive electrodes at p-junctions will have a shorter hole transport time along the lateral direction and thus a more efficient current spreading and a larger luminescence area. In addition, a shorter hole transport time will also expedite hole capture processes and result in a shorter capture time and better light emitting efficiency. Furthermore, as more carrier injected into the active regions of LEDs, thanks to graphene transparent conductive electrodes, excessive carriers need more time to proceed carrier recombination processes in QWs and result in a longer carrier recombination time. In short, the LED samples, with the help of graphene electrodes, are shown to have a better carrier transport efficiency, better carrier capture efficiency, and more electron-hole recombination. These research results provide important information for the carrier transport, carrier capture, and recombination processes in InGaN/GaN MQW LEDs with graphene transparent conductive electrodes.

Improved Microstructure and Hardness Properties of Low-Temperature Microwave-Sintered Y2O3 Stabilized ZrO2 Ceramics with Additions of Nano TiO2 Powders.

This paper reports the improvement of microstructural and hardness properties of 3 mol% yttria-stabilized zirconia (3Y-TZP) ceramics with nano TiO2 powders (with 0, 0.9, 1.8, and 2.7 wt%) added using a low-temperature microwave-assisted sintering of 1250 °C. Even at such a low sintering temperature, all sintered samples had the main phase of tetragonal zirconia (t-ZrO2) without the appearance of the secondary monoclinic phase or TiO2 phase, and had high relative densities, larger than 95%. The grain growth was well developed, and the grain sizes were around 300-600 nm. The Ti and O elements appeared at the grain and grain boundary and increased with the increased nano TiO2 contents identified by the element analysis, although the TiO2 phase did not appear in the X-ray pattern. The Vickers hardness was in the range of 10.5 to 14.5 GPa, which first increased with increasing content till 0.9 wt% and then decreased. With citric acid corrosion treatment for 10 h, the Vickers hardness only decreased from 14.34 GPa to 13.55 GPa with the addition of 0.9 wt% nano TiO2 powder. The experiment results showed that 0.9 wt% nano TiO2 addition can improve the densification as well as the Vickers hardness under a low temperature of microwave-assisted sintering.

Impacts of Intralipid on Nanodrug Abraxane Therapy and on the Innate Immune System.

A major obstacle to nanodrugs-mediated cancer therapy is their rapid uptake by the reticuloendothelial system that decreases the systemic exposure of the nanodrugs to tumors and also increases toxicities. Intralipid has been shown to reduce nano-oxaliplatin-mediated toxicity while improving bioavailability. Here, we have found that Intralipid reduces the cytotoxicity of paclitaxel for human monocytic cells, but not for breast, lung, or pancreatic cancer cells. Intralipid also promotes the polarization of macrophages to the anti-cancer M1-like phenotype. Using a xenograft breast cancer mouse model, we have found that Intralipid pre-treatment significantly increases the amount of paclitaxel reaching the tumor and promotes tumor apoptosis. The combination of Intralipid with half the standard clinical dose of Abraxane reduces the tumor growth rate as effectively as the standard clinical dose. Our findings suggest that pre-treatment of Intralipid has the potential to be a powerful agent to enhance the tumor cytotoxic effects of Abraxane and to reduce its off-target toxicities.

Growth and characterization of textured well-faceted ZnO on planar Si(100), planar Si(111), and textured Si(100) substrates for solar cell applications.

In this work, textured, well-faceted ZnO materials grown on planar Si(100), planar Si(111), and textured Si(100) substrates by low-pressure chemical vapor deposition (LPCVD) were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and cathode luminescence (CL) measurements. The results show that ZnO grown on planar Si(100), planar Si(111), and textured Si(100) substrates favor the growth of ZnO(110) ridge-like, ZnO(002) pyramid-like, and ZnO(101) pyramidal-tip structures, respectively. This could be attributed to the constraints of the lattice mismatch between the ZnO and Si unit cells. The average grain size of ZnO on the planar Si(100) substrate is slightly larger than that on the planar Si(111) substrate, while both of them are much larger than that on the textured Si(100) substrate. The average grain sizes (about 10-50 nm) of the ZnO grown on the different silicon substrates decreases with the increase of their strains. These results are shown to strongly correlate with the results from the SEM, AFM, and CL as well. The reflectance spectra of these three samples show that the antireflection function provided by theses samples mostly results from the nanometer-scaled texture of the ZnO films, while the micrometer-scaled texture of the Si substrate has a limited contribution. The results of this work provide important information for optimized growth of textured and well-faceted ZnO grown on wafer-based silicon solar cells and can be utilized for efficiency enhancement and optimization of device materials and structures, such as heterojunction with intrinsic thin layer (HIT) solar cells.

Hydrogen sulfide promotes adipogenesis in 3T3L1 cells.

The effect of hydrogen sulfide (H2S) on differentiation of 3T3L1-derived adipocytes was examined. Endogenous H2S was increased after 3T3L1 differentiation. The expression of the H2S-synthesising enzymes, cystathionine γ-lyase (CSE), cystathionine ß-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST), was increased in a time-dependent manner during 3T3L1 differentiation. Expression of genes associated with adipogenesis related genes including fatty acid binding protein 4 (FABP4/aP2), a key regulator of this process, was increased by GYY4137 (a slow-releasing H2S donor compound) and sodium hydrosulfide (NaHS, a classical H2S donor) but not by ZYJ1122 or time-expired NaHS. Furthermore expression of these genes were reduced by aminooxyacetic acid (AOAA, CBS inhibitor), DL-propargylglycine (PAG, CSE inhibitor) as well as by CSE small interference RNA (siCSE) and siCBS. The size and number of lipid droplets in mature adipocytes was significantly increased by both GYY4137 and NaHS, which also impaired the ability of CL316,243 (ß3-agonist) to promote lipolysis in these cells. In contrast, AOAA and PAG had the opposite effect. Taken together, we show that the H2S-synthesising enzymes CBS, CSE and 3-MST are endogenously expressed during adipogenesis and that both endogenous and exogenous H2S modulate adipogenesis and adipocyte maturation.

Numerical simulations of the current-matching effect and operation mechanisms on the performance of InGaN/Si tandem cells.

Numerical simulations are conducted to study the current-matching effect and operation mechanisms in and to design the optimized device structure of InGaN/Si tandem cells. The characteristics of short circuit current density (J sc), open circuit voltage (V oc), fill factor (FF), and conversion efficiency (η) of InGaN/Si tandem cells are determined by the current-matching effect. The similar trend of η to that of J sc shows that J sc is a dominant factor in determining the performance of InGaN/Si tandem cells. In addition, the combined effects of the J sc, V oc, and FF lead to an optimized η in the medium-indium, [Formula: see text], InGaN/Si tandem cell. At [Formula: see text], the J sc of the InGaN subcell is equal to that of the Si subcell such that an InGaN/Si tandem cell reaches the current matching condition to operate at the maximum power point. Similar to the J sc and FF, the η for low- [Formula: see text] and high-In [Formula: see text] InGaN/Si tandem cells are InGaN- and Si subcell-limited, respectively. Furthermore, the p- and n-layer thicknesses, indium content, and position of depletion region of InGaN subcell should be adjusted to reapportion the light between the two subcells and to achieve the maximum conversion efficiency. With appropriate thicknesses of p- and n-InGaN, In0.5-0.6Ga0.5-0.4 N/Si tandem cells can exhibit as high as approximately 34% to 36.5% conversion efficiency, demonstrating that a medium-indium InGaN/Si tandem cell results in a high-efficiency solar cell. Simulation results determine that the current-matching effect and operation mechanisms of InGaN/Si tandem cells can be utilized for efficiency enhancement through the optimized device structures.

Deletion of chromosome region 18q21.3-->qter in a patient: clinical, endocrine and imaging abnormalities.

Deletion of chromosome 18q (18q-) is a survivable autosomal abnormality, having an estimated incidence of one in 40,000 live births. Common features of affected individuals include developmental delay, growth retardation, hearing impairment, delayed myelination of the brain, and craniofacial dysmorphism. We describe herein a girl with psychomotor retardation and characteristic midface hypoplasia. The clinical, radioimaging, and cytogenetic findings as occur in 18q- are compared with a terminal deletion in the long arm of chromosome 18. We also monitored the effects of growth hormone treatment for changes in growth, and the patient's height velocity increased from 3.5 cm/yr to 7 cm/yr. Her nonverbal intelligence quotient (nIQ) increased from 30 to 48. Cognition of this patient is significantly improved. However, the brain MRI was not significantly improved after growth hormone treatments changes.