Scaffold-supported Transplantation of Islets in the Epididymal Fat Pad of Diabetic Mice

Islet transplantation has been clinically proven to be effective at treating type 1 diabetes. However, the current intrahepatic transplantation strategy ...

Peking University

A practical process to fabricate InGaN/GaN multiple quantum well light emitting diodes (LEDs) with a self-organized nanorod structure is demonstrated. The nanorod array is realized by using nature lithography of surface patterned silica spheres followed by dry etching. A layer of spin-on-glass (SOG), which intervening the rod spacing, serves the purpose of electric isolation to each of the parallel nanorod LED units. The electroluminescence peak wavelengths of the nanorod LEDs nearly remain as constant for an injection current level between 25mA and 100mA, which indicates that the quantum confined stark effect is suppressed in the nanorod devices. Furthermore, from the Raman light scattering analysis we identify a strain relaxation mechanism for lattice mismatch layers in the nanostructure.

GaN nanorod light emitting diode arrays with a nearly constant electroluminescent peak wavelength.

In this work, n-ZnO/p-Si photodiodes were fabricated and characterized to explore their potential applications in solar cells. With a coating of silica nanoparticles, we observed the enhancement of photoresponsivity and acceptance angle at a wavelength between 400 and 650 nm. The 17.6% increase of the photoresponsivity over the conventional device is due to the improved optical transmission toward the semiconductor through the silica nanoparticles. Furthermore, the acceptance angle of the nanoparticle coated device is dramatically increased, which is attributed to the effect of Bragg diffraction.

Nanoparticle-coated n-ZnO/p-Si photodiodes with improved photoresponsivities and acceptance angles for potential solar cell applications.

In this work, GZO/ZnO/GaN diodes with the light emitting ZnO layer sandwiched between two SiO(2) thin films was fabricated and characterized. We observed a strong excitonic emission at the wavelength 377nm with the Mg(2+) deep level transition and oxygen vacancy induced recombination significantly suppressed. In comparison, light emission from the GZO/GaN device (without SiO(2) barriers) is mainly dominant by defect radiation. Furthermore, the device with confinement layers demonstrated a much higher UV intensity than the blue-green emission of the GZO/GaN p-n device.

UV light emission from GZO/ZnO/GaN heterojunction diodes with carrier confinement layers.

In this work, n-GZO/a:amorphous-Si(i:intrinsic)/p( + )-Si photodiodes are fabricated. We employed a nanosphere lithographic technique to obtain nanoscale patterns on either the a-Si(i) or p( + )-Si surface. As compared with the planar n-GZO/p( + )-Si diode, the devices with nanopatterned a-Si(i) and nanopatterned p( + )-Si substrates show a 32% and 36.2% enhancement of photoresponsivity. Furthermore, the acceptance angle measurement reveals that the nanostructured photodiodes have larger acceptance angles than the planar structure. It also shows that the device with the nanocone structure has a higher acceptance angle than that with the nanorod structure.

Investigation of light absorption properties and acceptance angles of nanopatterned GZO/a-Si/p(+)-Si photodiodes.

We fabricated InGaN/GaN nanorod light emitting diode (LED) arrays using nanosphere lithography for nanorod formation, PECVD (plasma enhanced chemical vapor deposition) grown SiO(2) layer for sidewall passivation, and chemical mechanical polishing for uniform nanorod contact. The nano-device demonstrates a reverse current 4.77nA at -5V, an ideality factor 7.35, and an optical output intensity 6807mW/cm(2) at the injection current density 32A/cm(2) (20mA). Moreover, the investigation of the droop effect for such a nanorod LED array reveals that junction heating is responsible for the sharp decrease at the low current.

High performance InGaN/GaN nanorod light emitting diode arrays fabricated by nanosphere lithography and chemical mechanical polishing processes.

For InGaN/GaN based nanorod devices using a top-down etching process, the optical output power is affected by non-radiative recombination due to sidewall defects (which decrease light output efficiency) and the mitigated quantum confined Stark effect (QCSE) due to strain relaxation (which increases internal quantum efficiency). Therefore, the exploration of low-temperature optical behaviors of nanorod light emitting diodes (LEDs) will help identify the correlation between these two factors. In this work, low-temperature electroluminescent (EL) spectra of InGaN/GaN nanorod arrays were explored and compared with those of planar LEDs. The nanorod LED exhibits a much higher optical output percentage increase when the temperature decreases. The increase is mainly attributed to the increased carriers in the quantum wells for radiative recombination. Also, due to a better spatial overlap of electrons and holes in the quantum wells, the increased number of carriers can be more efficiently recombined in the nanorod device. Next, while the nanorod array shows nearly constant peak energy in the EL spectra at various injection currents at the temperature of 300 K, a blue shift has been observed at 190 K. The results suggest that with less non-radiative recombination and thus more carriers in the quantum wells, carrier screening and band filling still prevail in the partially strain relaxed nanorods. Moreover, when the temperature drops to 77 K, the blue shift of both nanorod and planar devices disappears and the optical output power decreases since there are fewer carriers in the quantum wells for radiative recombination.

Investigation of low-temperature electroluminescence of InGaN/GaN based nanorod light emitting arrays.

Low-temperature electroluminescence from ZnO nanowire light-emitting arrays is reported. By inserting a thin MgO current blocking layer in between ZnO nanowire and p-GaN, high-purity UV light emission at wavelength 398 nm was obtained. As the temperature is decreased, contrary to the typical GaN-based light emitting diodes, our device shows a decrease of optical output intensity. The results are associated with various carrier tunneling processes and frozen MgO defects.

Characterizations of low-temperature electroluminescence from ZnO nanowire light-emitting arrays on the p-GaN layer.

Strain in the semiconductor light emitting layers has profound effect on the energy band structure and the optical properties of the light emitting diodes (LEDs). Here, we report the fabrication and characterization of GaN nanorod LED arrays. We found that the choice of nanorod passivation materials results in the variation of strain in the InGaN/GaN quantum wells, and thus the corresponding change of light emission properties. The results were further investigated by performing Raman measurement to understand the strain of nanorods with different passivation materials and by calculating the optical transition energy of the devices under the influence of strain-induced deformation potential and the piezoelectric polarization field.

Investigation of the strain induced optical transition energy shift of the GaN nanorod light emitting diode arrays.

Despite tremendous efforts on improving the solar cell conversion efficiency at normal incidence, improvement at oblique angles has not been widely addressed, not to mention the corresponding light absorption behaviors at different polarizations. Here we report the characterization of the solar cell conversion efficiency and the spectra of photoresponsivity at various tilted angles. The results show that TM (transverse magnetic) polarized light possesses higher photoresponsivity than TE (transverse electric) polarized light and the difference becomes larger with the incidence angle. To address the issue, a monolayer of silica nanoparticles on the solar cell surface was employed to improve the light absorption. Even though both TE and TM waves show a decrease in the surface reflectivity with the presence of nanoparticles, the interaction between the silica particles and the TE wave is more significant. The improvement of the conversion efficiency for obliquely incident light is explained from the refractive index difference of the nanoparticles for the TE and TM polarizations.

Polarization dependent solar cell conversion efficiency at oblique incident angles and the corresponding improvement using surface nanoparticle coating.

To observe the curative effect of Xeloda in meibomian gland carcinoma.

Recrudescent meibomian gland carcinoma treated with Xeloda: case report.

The effects of class I PI3K inhibitor NVP-BKM120 on cell proliferation, cell cycle distribution, cellular apoptosis, phosphorylation of several proteins of the PI3K/AKT signaling pathway and the mRNA expression levels of HIF1-α, VEGF and MMP9 in the acquired gefitinib resistant cell line H1975 were investigated, and whether NVP-BKM120 can overcome the acquired resistance caused by the EGFR T790M mutation and the underlying mechanism were explored. MTT assay was performed to detect the effect of gefitinib, NVP-BKM120, NVP-BKM120 plus 1 μmol/L gefitinib on growth of H1975 cells. The distribution of cell cycle and apoptosis rate of H1975 cells were examined by using flow cytometry. The mRNA expression levels of tumor-related genes such as HIF1-α, VEGF and MMP9 were detected by using real-time quantitative PCR. Western blotting was used to detect the expression level of phosphorylated proteins in the PI3K/AKT signaling pathway, such as Ser473-p-AKT, Ser235/236-p-S6 and Thr70-p-4E-BP1, as well as total AKT, S6 and 4E-BP1. The results showed that the NVP-BKM120 could inhibit the growth of H1975 cells in a concentration-dependent manner, and H1975 cells were more sensitive to NVP-BKM120 than gefitinib (IC50:1.385 vs. 15.09 μmol/L respectively), whereas combination of NVP-BKM120 and gefitinib (1 μmol/L) did not show more obvious effect than NVP-BKM120 used alone on inhibition of cell growth (P>0.05). NVP-BKM120 (1 μmol/L) increased the proportion of H1975 cells in G0-G1 phase and the effect was concentration-dependent, and 2 μmol/L NVP-BKM120 promoted apoptosis of H1975 cells. There was no significant difference in the proportion of H1975 cells in G0-G1 phase and apoptosis rate between NVP-BKM120-treated alone group and NVP-BKM120 plus genfitinib (1 μmol/L)-treated group or between DMSO-treated control group and gefitinib (1 μmol/L)-treated alone group (P>0.05 for all). It was also found that the mRNA expression levels of these genes were down-regulated by NVP-BKM120 (1 μmol/L), and NVP-BKM120 (1 μmol/L) or NVP-BKM120 (1 μmol/L) plus gefitinib (1 μmol/L) obviously inhibited the activation of Akt, S6 and 4E-BP1 as compared with control group, but single use of gefitinib (1 μmol/L) exerted no significant effect. These data suggested that NVP-BKM120 can overcome gefitinib resistance in H1975 cells, and the combination of NVP-BKM120 and gefitinib did not have additive or synergistic effects. It was also concluded that NVP-BKM120 could overcome the acquired resistance to gefitinib by down-regulating the phosphorylated protein in PI3K/AKT signal pathways in H1975 cells, but it could not enhance the sensitivity of H1975 cells to gefitinib.

Effects of PI3K inhibitor NVP-BKM120 on acquired resistance to gefitinib of human lung adenocarcinoma H1975 cells.

Gefitinib is an epidermal growth factor receptor (EGFR) inhibitor, which is used to treat patients with advanced non-small cell lung cancer (NSCLC) harboring EGFR mutations. Dermatological reactions are the most common adverse events associated with gefitinib treatment; other adverse effects, including diarrhea, nausea, stomatitis and an asymptomatic elevation of liver enzymes have also been reported. The present study describes a patient with intestinal obstruction who was successfully undergoing treatment with gefitinib for primary and metastatic neoplasms. Gefitinib-induced intestinal obstruction has not been previously reported; therefore, careful monitoring of gastrointestinal symptoms should be conducted throughout the course of gefitinib-treated malignancies.

Liang-yi Chen

Institute of Molecular Medicine

Peking University

Scaffold-supported Transplantation of Islets in the Epididymal Fat Pad of Diabetic Mice

Liang-yi Chen

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Institute of Molecular Medicine

Peking University

Scaffold-supported Transplantation of Islets in the Epididymal Fat Pad of Diabetic Mice

Institute of Molecular Medicine