Development of High-Performance Detector Technology for UV and IR Applications

Sensing and imaging for ultraviolet (UV) and infrared (IR) bands has many applications for NASA, defense, and commercial systems. Recent work has involved developing UV avalanche photodiode (UVAPD) arrays with high gain for high resolution imaging. Various GaN/AlGaN p-i-n UV-APDs have been fabricated from epitaxial structures grown by metalorganic chemical vapor deposition (MOCVD) on GaN substrates with avalanche gains greater than 5105, and high responsivities. Similarly, the IR spectral band is useful for measuring ocean temperatures, atmospheric aerosols, forest fires, etc. We are also developing room temperature operating graphene-enhanced PbSe midwave infrared (MWIR) detectors and focal plane arrays (FPAs). These compact and low-cost MWIR sensors can benefit various NASA remote sensing applications. Here we present recent results from these high performance UV- and IR-band detector and FPA technologies

GaN/AlGaN Avalanche Photodiode Detectors for High Performance Ultraviolet Sensing Applications

The shorter wavelengths of the ultraviolet (UV) band enable detectors to operate with increased spatial resolution, variable pixel sizes, and large format arrays, benefitting a variety of NASA, defense, and commercial applications. AlxGa1-xN semiconductor alloys, which have attracted much interest for detection in the UV spectral region, have been shown to enable high optical gains, high sensitivities with the potential for single photon detection, and low dark current performance in ultraviolet avalanche photodiodes (UV-APDs). We are developing GaN/AlGaN UV-APDs with large pixel sizes that demonstrate consistent and uniform device performance and operation. These UV-APDs are fabricated through high quality metal organic chemical vapor deposition (MOCVD) growth on lattice-matched, low dislocation density GaN substrates with optimized material growth and doping parameters. The use of these low defect density substrates is a critical element to realizing highly sensitive UV-APDs and arrays with suppressed dark current under high electric fields.Optical gains greater than 5X10 (exp 6) with enhanced quantum efficiencies over the 350-400 nm spectral range have been demonstrated, enabled by a strong avalanche multiplication process. Furthermore, we are developing 6X6 arrays of devices to test high gain UV-APD array performance at ~355 nm. These variable-area GaN/AlGaN UV-APD detectors and arrays enable advanced sensing performance over UV bands of interest with high resolution detection for NASA Earth Science applications

Development of High-Performance Graphene-HgCdTe Detector Technology for Mid-Wave Infrared Applications

A high-performance graphene-based HgCdTe detector technology is being developed for sensing over the mid-wave infrared (MWIR) band for NASA Earth Science, defense, and commercial applications. This technology involves the integration of graphene into HgCdTe photodetectors that combines the best of both materials and allows for higher MWIR(2-5 m) detection performance compared to photodetectors using only HgCdTe material. The interfacial barrier between the HgCdTe-based absorber and the graphene layer reduces recombination of photogenerated carriers in the detector. The graphene layer also acts as high mobility channel that whisks away carriers before they recombine, further enhancing the detector performance. Likewise, HgCdTe has shown promise for the development of MWIR detectors with improvements in carrier mobility and lifetime. The room temperature operational capability of HgCdTe-based detectors and arrays can help minimize size, weight, power and cost for MWIR sensing applications such as remote sensing and earth observation, e.g., in smaller satellite platforms. The objective of this work is to demonstrate graphene-based HgCdTe room temperature MWIR detectors and arrays through modeling, material development, and device optimization. The primary driver for this technology development is the enablement of a scalable, low cost, low power, and small footprint infrared technology component that offers high performance, while opening doors for new earth observation measurement capabilities

Study of prescribing pattern of antihypertensive drugs in diabetic patients in a tertiary care centre, Vizianagaram, India

Background: Diabetes mellitus (DM) and Hypertension (HTN) are the two major chronic disorders frequently coexisting, with increased incidence with age. HTN is about twice as common in patients with DM. Prescribing pattern are powerful tools to ascertain the role of drugs in society. There are many variations in prescribing patterns of antihypertensive drugs in patients with HTN and DM. Since these patients requires lifelong treatment it has enormously increased the burden of patients particularly in developing countries like India. Physician needs to be more concerned while choosing drugs for the patients with HTN and DM. In a tertiary care hospital, there is a real need for drug utilization study to determine the appropriate, more safe and effective patterns of drug therapy among diabetic hypertensive patients.Methods: A Cross sectional observational study was conducted in Maharajah’s Institute of Medical Sciences from December 2016 to May 2018. A total of 360 prescriptions of the patients with hypertension and coexisting diabetes were analyzed. The prescriptions prescribed to these patients were collected, assessed and the following parameters were noted. The treatment pattern of different group of drugs for HTN with co-existing DM was evaluated. The intended work was divided into three steps: Step 1: To collect the prescriptions of hypertensive patients with DM. Step 2: To separate the prescriptions prescribing anti hypertensive Drugs. Step 3: To statistically analyze the prescriptions. Relevant information was recorded in a structured proforma & data was evaluated.Results: In this study it was found that 36% of the patients were in the age group of 51-60 years with female preponderance among diabetic hypertensive patients. 77% of patients were treated with single antihypertensive drug and 23% of patients were treated with antihypertensive drug combinations. In monotherapy, telmisartan was most commonly prescribed. In combination therapy, amlodipine and telmisartan followed by amlodipine and atenolol were used.Conclusions: In this study monotherapy was preferred compared to combination therapy and adherence to the JNC 7 guidelines was good except in case of usage of diuretics

Development of High Performance Detector Technology for UV and Near IR Applications

Sensing and imaging for ultraviolet (UV) and nearinfrared (NIR) bands has many applications forNASA, defense, and commercial systems. Recentwork has involved developing UV avalanchephotodiode (UV-APD) arrays with high gain for highresolution imaging. Various GaN/AlGaN p-i-n (PIN)UV-APDs have been fabricated from epitaxialstructures grown by MOCVD on GaN substrates withavalanche gains higher than 5 x 10(exp 5), and significantlyhigher responsivities. Likewise, the SiGe materialsystem allows the demonstration of high-performancedetector array technology that covers the 0.5 to 1.7 mwavelength range for visible and NIR bands ofinterest. We have utilized SiGe fabrication technologyto develop Ge based PIN detector devices on 300 mmSi wafers. We will discuss the theoretical andexperimental results from electrical and opticalcharacterization of the detector devices with variousn+ region doping concentrations to demonstrate low dark currents below 1 uA at -1 V and high photocurrent. Recent results from these detectorarrays for UV and NIR detection will be presented

Evaluation of Pain Experience During and After Scaling and Root Planing (SRP) Using Local / Topical Anesthetic Agents: A Comparative Study

ABSTRACT To evaluate the pain experience of the patient during and after scaling and root planing (SRP) using local or topical anesthetic agents. A total of 30 Chronic Periodontitis patients participated in this study. Three quadrants in each patient were randomly allotted to receive non-surgical periodontal therapy i.e. scaling & root planing (SRP) with 2% lidocaine injection (Group 1) or topical application of 8% Lidocaine + 0.8% Dibucaine (Group 2) or 2% lidocaine gel (Group 3). Pain was assessed midway through the treatment and immediately after treatment (post-operatively) using Visual Analogue Scale (VAS). The patients were asked about pain /discomfort following treatment after one day and their preference for the anesthetic if any. ANOVA followed by Bonferroni's post hoc Analysis was used to compare the mean pain score in all the three study groups. Paired t-tests were used to analyse pain scores during and after treatment in each groups. The inter-group comparisons of mean pain score in all the 3 study groups during procedure and post-operatively among the groups were statistically significant(< 0.05) but pain scores during the procedure between group 2 and group 3 were not statistically significant (0.061). The experience of pain or discomfort one day post operatively was significantly higher in Group1 (2% Lidocaine Injection) 70% compared to Group 2 (8% Lidocaine + 0.8% Dibucaine) 36.70% and group 3 (2% Lidocaine Topical) 46.70%. Though 56.70% of the patients in the study preferred (8% Lidocaine + 0.8% Dibucaine) anesthetic gel for procedure over 2% Lidocaine anesthetic Injection and 2% Lidocaine Topical. Lidocaine Injection 2% was more effective in controlling pain during scaling and root planing than 8% Lidocaine + 0.8% Dibucaine and 2% Lidocaine Topical, but 8% Lidocaine + 0.8% Dibucaine anesthetic gel had less pain/discomfort one day post-operatively and most preferred anesthetic when compared with other two as it avoided postoperative numbness, fear from needle prick and favourable taste of the anesthetic gel

Entanglement demonstration on board a nano-satellite

Global quantum networks for secure communication can be realized using large fleets of satellites distributing entangled photon pairs between ground-based nodes. Because the cost of a satellite depends on its size, the smallest satellites will be most cost-effective. This Letter describes a miniaturized, polarization entangled, photon-pair source operating on board a nano-satellite. The source violates Bell’s inequality with a Clauser–Horne–Shimony–Holt parameter of 2.60±0.06. This source can be combined with optical link technologies to enable future quantum communication nano-satellite missions

SpooQy-1: The First Nano-Satellite to Demonstrate Quantum Entanglement in Space

SpooQy-1 is a 3-unit nanosatellite that was launched into a Low Earth Orbit from the International Space Station on the 17th of June 2019. The spacecraft hosts a scientific payload capable of producing entangled photon-pairs and measuring their polarization in orthogonal bases to perform a Bell test. Since launch, SpooQy-1 has routinely demonstrated the generation and detection of polarization entangled photon-pairs in Space, something that has previously only been demonstrated by the 630kg Micius mission by the Chinese Academy of Sciences. The measured entanglement correlations can violate Bell\u27s inequality with a CHSH parameter value of 2.60±0.06, over operating temperatures of 16 °C to 21.5 °C. These results demonstrate that quantum entanglement can be generated in space on highly resource-constrained platforms. A follow-on 12U mission, developed in partnership with RAL space,will build on this to demonstrate space-to-ground entanglement distribution, which is required for space-based nodes to support global quantum communication networks

Doping and Transfer of High Mobility Graphene Bilayers for Room Temperature Mid-Wave Infrared Photodetectors

High-performance graphene-HgCdTe detector technology has been developed combining the best properties of both materials for mid-wave infrared (MWIR) detection and imaging. The graphene functions as a high mobility channel that whisks away carriers before they can recombine, further contributing to detection performance. Comprehensive modeling on the HgCdTe, graphene, and the HgCdTe-graphene interface has aided the design and development of this MWIR detector technology. Chemical doping of the bilayer graphene lattice has enabled p-type doping levels in graphene for high mobility implementation in high-performance MWIR HgCdTe detectors. Characterization techniques, including SIMS and XPS, confirm high boron doping concentrations. A spin-on doping (SOD) procedure is outlined that has provided a means of doping layers of graphene on native substrates, while subsequently allowing integration of the doped graphene layers with HgCdTe for final implementation in the MWIR photodetection devices. Successful integration of graphene into HgCdTe photodetectors can thus provide higher MWIR detector efficiency and performance compared to HgCdTe-only detectors. New earth observation measurement capabilities are further enabled by the room temperature operational capability of the graphene-enhanced HgCdTe detectors and arrays to benefit and advance space and terrestrial applications

Paths to Innovation in Supply Chains: The Landscape of Future Research

This chapter presents a Strategic Research and Innovation Agenda for supply chain and it is the result of an intensive work jointly performed involving a wide network of stakeholders from discrete manufacturing, process industry and logistics sector to put forward a vision to strengthen European Supply Chains for the next decade. The work is based on matching visions from literature and from experts with several iterations between desk research and workshops, focus groups and interviews. The result is a detailed analysis of the supply chain strategies identified as most relevant for the next years and definition of the related research and innovation topics as future developments and steps for the full implementation of the strategies, thus proposing innovative and cutting-edge actions to be implemented based on technological development and organisational change