Bandgap-Engineered HgCdTe Infrared Detector Structures for Reduced Cooling Requirements.

State-of-the-art mercury cadmium telluride (HgCdTe) high performance infrared (IR) p-n heterojunction technology remains limited by intrinsic, thermal Auger generation- recombination (G-R) mechanisms which necessitate strict cooling requirements, and challenges related to processing technology, particularly those associated with achieving stable, controllable in situ p-type doping in molecular beam epitaxy (MBE) grown HgCdTe. These limitations motivate the need to firstly, increase device operating temperatures, and secondly, address material processing issues. This work investigates three alternative HgCdTe IR device architectures as proposed solutions: 1) the high operating temperature (HOT) detector, 2) the nBn detector, and 3) the NBnuN detector. The HOT detector is designed to suppress Auger processes, in turn, reducing the detector noise and cryogenic cooling requirements. A simulation study comparing the device behavior and performance metrics of the Auger-suppressed HOT structure to those obtained for the conventional double layer planar heterostructure (DLPH) device predicts the HOT detector can provide a significant advantage over conventional detectors with an increased operating temperature of ~40-50 K for devices with cutoff wavelengths in the range of 5-12 um. In a related study, a series of experiments is conducted to examine arsenic (As) deep diffusion in HgCdTe with the goal of achieving controllable low p-type doping in the HOT absorber layer to reduce Auger G-R processes by increasing minority carrier lifetimes. Furthermore, a unipolar, barrier-integrated nBn detector structure is proposed to address the challenges associated with p-type doping in MBE grown HgCdTe. Numerically simulated performance characteristics of the HgCdTe nBn device predict values similar to comparable DLPH structures for a range of temperatures, motivating the experimental demonstration of mid- and long-wave IR HgCdTe nBn detectors. Fabricated nBn detectors successfully exhibit barrier-influenced current-voltage and photoresponse characteristics, but are limited by perimeter leakage currents which must be resolved in future work. Finally, this work culminates with the simulation study of the novel, hybrid NBnuN structure which addresses both technology limitations by combining the advantages and designs of the Auger-suppressed HOT and unipolar nBn detectors in a single configuration.Ph.D.Electrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/91390/1/aitsuno_1.pd

Carcinoma Arising from Brunner's Gland in the Duodenum after 17 Years of Observation – A Case Report and Literature Review

A 60-year-old man presented with melena and hematemesis in 1984. Esophagogastroduodenoscopy (EGD) detected a small protruding lesion in the duodenal bulb, which was diagnosed as Brunner's adenoma. No significant change was detected in subsequent annual EGD and biopsies for 10 years, after which the patient was not observed for 7 years. The patient presented with melena again in 2001. The lesion had changed shape to become a 10 mm sessile tumor with a central depression, and following a biopsy was diagnosed as an adenocarcinoma. The patient underwent partial resection of the duodenum. Histopathological assessment showed acidophilic cells with swollen nuclei, and clear cells forming a tubular or papillary tubule in the mucosal lamina propria and submucosal layer. The tumor cells stained positive for lysozyme, indicating that they arose from Brunner's gland. The patient showed no sign of recurrence and was disease-free for more than 34 months after surgery. The patient died of pneumonia. This is an extremely rare case of primary duodenal carcinoma arising from Brunner's gland in a patient observed for 17 years

A Journey from Thermally Tunable Synthesis to Spectroscopy of Phenylmethanimine in Gas Phase and Solution

Phenylmethanimine is an aromatic imine with a twofold relevance in chemistry: organic synthesis and astrochemistry. To tackle both aspects, a multidisciplinary strategy has been exploited and a new, easily accessible synthetic approach to generate stable imine-intermediates in the gas phase and in solution has been introduced. The combination of this formation pathway, based on the thermal decomposition of hydrobenzamide, with a state-of-the-art computational characterization of phenylmethanimine laid the foundation for its first laboratory observation by means of rotational electric resonance spectroscopy. Both E and Z isomers have been accurately characterized, thus providing a reliable basis to guide future astronomical observations. A further characterization has been carried out by nuclear magnetic resonance spectroscopy, showing the feasibility of this synthetic approach in solution. The temperature dependence as well as possible mechanisms of the thermolysis process have been examined. © 2020 The Authors. Published by Wiley-VCH Gmb

Valorisation of Biowastes for the Production of Green Materials Using Chemical Methods

With crude oil reserves dwindling, the hunt for a sustainable alternative feedstock for fuels and materials for our society continues to expand. The biorefinery concept has enjoyed both a surge in popularity and also vocal opposition to the idea of diverting food-grade land and crops for this purpose. The idea of using the inevitable wastes arising from biomass processing, particularly farming and food production, is, therefore, gaining more attention as the feedstock for the biorefinery. For the three main components of biomass—carbohydrates, lipids, and proteins—there are long-established processes for using some of these by-products. However, the recent advances in chemical technologies are expanding both the feedstocks available for processing and the products that be obtained. Herein, this review presents some of the more recent developments in processing these molecules for green materials, as well as case studies that bring these technologies and materials together into final products for applied usage