Quantum-well infrared photodetector structure synthesis: Methodology and experimental verification

© 2003 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.DOI: 10.1109/JQE.2002.80816

The role of depression, anxiety and illness characteristics on risky sexual behaviour among people with HIV

Background: People living with HIV (PLHIV) have a longer lifespan with treatment and continue to be sexually active. To date, the extent of risky sexual behaviour among local PLHIV and its associated factors were undetermined. Objective: To examine the role of depression, anxiety and illness characteristics on risky sexual behaviour among PLHIV attending care in a Malaysian tertiary reference hospital (N= 406). Methods: It was a cross-sectional study. Subjects were recruited by systematic random sampling. Risky sexual behaviour was determined by using the modified National Youth Risk Behaviour Survey. PHQ-9 and GAD-7 were used to measure the depressive and anxiety symptoms, respectively. Chi-square test was used to examine the association between the variables. Multiple logistic regression was used to examine the predictors of the study. A p value of less than 0.05 was considered significant and odds ratio was used as the measure of risk association. Results: Our study showed that 29.3% had risky sexual behaviour. Meanwhile, 21.9% and 26.4% had depressive and anxiety symptoms, respectively. Risky sexual behaviour was significantly associated with age, religion, education level, duration of HIV diagnosis, depressive and anxiety symptoms. From multivariate logistic regression, duration of HIV diagnosis and anxiety symptoms significantly predicted risky sexual behaviour. Conclusion: This study highlights that a substantial number of PLHIV had risky sexual behaviour and psychological symptoms. It is important for psychological interventions that reduce risky sexual behaviour among PLHIV who attend treatment, especially during the early phase

Progress in resonator quantum well infrared photodetector (R-QWIP) focal plane arrays

In this work, the performance of a 640 X 512 long-wavelength resonant quantum well infrared photodetector (R-QWIP) focal plane array (FPA) was evaluated as a function of operating temperature, bias, and photon flux using an F/2.2 optic. From these FPA measurements an assessment of the dark current, noise, conversion efficiency and noise-equivalent temperature difference is provided herein. Histogram results are used to support a statistical interpretation of operability and non-uniformity across the R-QWIP FPA. In addition, single pixel devices fabricated from the same wafer lot enabled supplemental noise gain and spectral response measurements. The spectral response of this R-QWIP structure was confirmed to peak around 8.3 microns with a spectral bandwidth or approximately 1 micron (full-width half maximum) and the noise gain measurements were used to provide an estimation of the expected external quantum efficiency (conversion efficiency = quantum efficiency ⁄ gain)

Structural and optical characterization of infrared hot electron transistor

We present structural, optical, and transport characterization of long wave infrared hot electron transistor (IHET) based on doped quantum wells of InGaAs/AlGaAs. The atomic resolution images and x-ray diffraction patterns verified a lattice matched and band-gap engineered device structure of IHET. Measured values of the photocurrent were less than the theoretically expected values and indicated a loss of photocurrent between the base of the IHET and the collector. A higher filter height due to high unexpected dopant in the filter barrier was suggested as a possible cause of the current loss. Photoluminescence data in the near infrared showed the existence of such a dopant. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3457122

Infrared Digital Focal Plane Arrays for Earth Remote Sensing Instruments

In this presentation, we will discuss the advantages of using an in-pixel digital read out integrated circuit and type-II strained layer superlattice detector array technology to elevate the operating temperature of the focal plane array for Earth remote sensing instruments

Retraction: Sung et al. Expression of SARS-CoV-2 Spike Protein Receptor Binding Domain on Recombinant B. subtilis on Spore Surface: A Potential COVID-19 Oral Vaccine Candidate. Vaccines 2022, 10, 2

The journal retracts the article “Expression of SARS-CoV-2 Spike Protein Receptor Binding Domain on Recombinant B. subtilis on Spore Surface: A Potential COVID-19 Oral Vaccine Candidate” [...

Expression of SARS-CoV-2 Spike Protein Receptor Binding Domain on Recombinant B. subtilis on Spore Surface: A Potential COVID-19 Oral Vaccine Candidate

Various types of vaccines, such as mRNA, adenovirus, and inactivated virus by injection, have been developed to prevent SARS-CoV-2 infection. Although some of them have already been approved under the COVID-19 pandemic, various drawbacks, including severe side effects and the requirement for sub-zero temperature storage, may hinder their applications. Bacillus subtilis (B. subtilis) is generally recognized as a safe and endotoxin-free Gram-positive bacterium that has been extensively employed as a host for the expression of recombinant proteins. Its dormant spores are extraordinarily resistant to the harsh environment in the gastrointestinal tract. This feature makes it an ideal carrier for oral administration in resisting this acidic environment and for release in the intestine. In this study, an engineered B. subtilis spore expressing the SARS-CoV-2 spike protein receptor binding domain (sRBD) on the spore surface was developed. In a pilot test, no adverse health event was observed in either mice or healthy human volunteers after three oral courses of B. subtilis spores. Significant increases in neutralizing antibody against sRBD, in both mice and human volunteers, after oral administration were also found. These findings may enable the further clinical developments of B. subtilis spores as an oral vaccine candidate against COVID-19 in the future

Compact Thermal Imager (CTI) for Atmospheric Remote Sensing

The demonstration of a newly developed compact thermal imager (CTI) on the International Space Station (ISS) has provided not only a technology advancement but a rich high-resolution dataset on global clouds, atmospheric and land emissions. This study showed that the free-running CTI instrument could be calibrated to produce scientifically useful radiance imagery of the atmosphere, clouds, and surfaces with a vertical resolution of ~460 m at limb and a horizontal resolution of ~80 m at nadir. The new detector demonstrated an excellent sensitivity to detect the weak limb radiance perturbations modulated by small-scale atmospheric gravity waves. The CTI’s high-resolution imaging was used to infer vertical cloud temperature profiles from a side-viewing geometry. For nadir imaging, the combined high-resolution and high-sensitivity capabilities allowed the CTI to better separate cloud and surface emissions, including those in the planetary boundary layer (PBL) that had small contrast against the background surface. Finally, based on the ISS’s orbit, the stable detector performance and robust calibration algorithm produced valuable diurnal observations of cloud and surface emissions with respect to solar local time during May–October 2019, when the CTI had nearly continuous operation