MOVPE of GaSb/InGaAsSb Multilayers and Fabrication of Dual Band Photodetectors

Metalorganic vapor phase epitaxy (MOVPE) of GaSb/InGaAsSb multilayer thin films and fabrication of bias-selectable dual band photodetectors are reported. For the dual band photodetectors the short wavelength detector, or the upper p- GaSb/n-GaSb junction photodiode, is placed optically ahead of the long wavelength one, or the lower photodiode. The latter is based on latticed-matched In0.13Ga0.87As0.11Sb0.89 with bandgap near 0.6 eV. Specifically, high quality multilayer thin films are grown sequentially from top to bottom as p+-GaSb/p-GaSb/n-GaSb/n-InGaAsSb/p-InGaAsSb/p-GaSb on undoped p-type GaSb substrate, and as n-GaSb/p-GaSb/p-InGaAsSb/n-InGaAsSb/n-GaSb on Te-doped n-type GaSb substrate respectively. The multilayer thin films are characterized by optical microscope, atomic force microscope (AFM), electron microprobe analyses etc. The photodiode mesa steps are patterned by photolithography with wet chemical etching and the front metallization is carried out by e-beam evaporation with Pd/Ge/Au/Ti/Au to give ohmic contact on both n- and p-type Sb based layer surfaces. Dark I-V measurements show typical diode behavior for both the upper and lower photodiodes. The photoresponsivity measurements indicate that both the upper and lower photodiodes can sense the infrared illumination corresponding to their cutoff wavelengths respectively, comparable with the simulation results. More work is underway to bring the long wavelength band to the medium infrared wavelength region near 4 micrometers

Heat Shock Protein 70 Protects the Heart from Ischemia/Reperfusion Injury through Inhibition of p38 MAPK Signaling.

BackgroundHeat shock protein 70 (Hsp70) has been shown to exert cardioprotection. Intracellular calcium ([Ca2+]i) overload induced by p38 mitogen-activated protein kinase (p38 MAPK) activation contributes to cardiac ischemia/reperfusion (I/R) injury. However, whether Hsp70 interacts with p38 MAPK signaling is unclear. Therefore, this study investigated the regulation of p38 MAPK by Hsp70 in I/R-induced cardiac injury.MethodsNeonatal rat cardiomyocytes were subjected to oxygen-glucose deprivation for 6 h followed by 2 h reoxygenation (OGD/R), and rats underwent left anterior artery ligation for 30 min followed by 30 min of reperfusion. The p38 MAPK inhibitor (SB203580), Hsp70 inhibitor (Quercetin), and Hsp70 short hairpin RNA (shRNA) were used prior to OGD/R or I/R. Cell viability, lactate dehydrogenase (LDH) release, serum cardiac troponin I (cTnI), [Ca2+]i levels, cell apoptosis, myocardial infarct size, mRNA level of IL-1β and IL-6, and protein expression of Hsp70, phosphorylated p38 MAPK (p-p38 MAPK), sarcoplasmic/endoplasmic reticulum Ca2+-ATPase2 (SERCA2), phosphorylated signal transducer and activator of transcription3 (p-STAT3), and cleaved caspase3 were assessed.ResultsPretreatment with a p38 MAPK inhibitor, SB203580, significantly attenuated OGD/R-induced cell injury or I/R-induced myocardial injury, as evidenced by improved cell viability and lower LDH release, resulted in lower serum cTnI and myocardial infarct size, alleviation of [Ca2+]i overload and cell apoptosis, inhibition of IL-1β and IL-6, and modulation of protein expressions of p-p38 MAPK, SERCA2, p-STAT3, and cleaved-caspase3. Knockdown of Hsp70 by shRNA exacerbated OGD/R-induced cell injury, which was effectively abolished by SB203580. Moreover, inhibition of Hsp70 by quercetin enhanced I/R-induced myocardial injury, while SB203580 pretreatment reversed the harmful effects caused by quercetin.ConclusionsInhibition of Hsp70 aggravates [Ca2+]i overload, inflammation, and apoptosis through regulating p38 MAPK signaling during cardiac I/R injury, which may help provide novel insight into cardioprotective strategies

Reproducibility studies on OCT rapid and repeated scanning method for the diagnosis of glaucoma

AIM: To evaluate the application ofoptical coherence tomography(OCT)and retinal nerve fiber layer thickness(RNFL)measured by rapid and repeated methods in the diagnosis of glaucoma repeated significance. <p>METHODS: Stratus OCT were measured in 38 normal subjects and 42 patients with the primary RNFL thickness of open angle glaucoma patients. Rapid and repeated scanning was applied respectively to measure the RNFL thickness of patients with normal and primary open angle glaucoma. The average RNFL thickness's related coefficient and various coefficient of the temporal, upper, lower and nasal region made reproducibility assessment. <p>RESULTS: In normal and primary open angle glaucoma patients, the overall average RNFL thickness and lateral temporal, above, nasal, below RNFL thickness, in which two groups did not show differences; repeated scanning average RNFL thickness was measured in fast scanning scheme around the optic disc, and had higher ICC and lower value of CV, there were significant differences in the temporal region(<i>P</i>=0.042). The temporal, nasal, upper and lower area of the retinal nerve fiber layer thickness of the ICC(CV)values were as follows: fast scan was 0.918(7.2%), 0.831(6.82%), 0.856(5.12%), 0.911(7.19%); repeated scans were 0.927(3.21%), 0.962(5.01%), 0.909(6.02%), 0.869(4.67%), 0.918(6.89%).<p>CONCLUSION: In normal subjects and patients with primary open angle glaucoma, the application of rapid and repeated scanning in measurement of RNFL with OCT thickness has repeated significance, but repeated scanning scheme in the assessment of RNFL thickness is more accurate

Immunomodulation of NK Cells under Ionizing Radiation

Natural killer (NK) cells are the effector lymphocytes of the innate immune system and control many types of tumors and microbial infections. Ionizing radiation (IR) has a pronounced effect on NK cells. However, the role of NK cells in radiotherapy remains elusive. In this chapter, we summarized the direct and indirect effects of ionizing radiation on NK cells. Low doses of ionizing radiation can enhance the toxic effects of NK cells. In contrast, high doses of ionizing radiation will lead to functional impairment of NK cells. In addition, under ionizing radiation, NK cells are also modulated by other immune cells. Overall, combining NK cell therapy and radiation therapy can improve the efficacy of oncology treatment

Protective effect of ginsenoside Rb1 against intestinal ischemia-reperfusion induced acute renal injury in mice

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