Studies of CO oxidation on Pt/SnO2 catalyst in a surrogate CO2 laser facility

Samples of 1% Pt/SnO2 catalyst were exposed to a stoichiometric gas mixture of 1% CO and 1.2% O2 in helium over a range of flowrates from 5 to 15 sccm and temperatures from 338 to 394 Kelvin. Reaction rate constants for the catalytic oxidation of carbon monoxide and their temperature dependence were determined and compared with previous literature values

Hermetic storage - an ecofriendly safe storage method for long term storage of black gram: Poster

India is the primary origin of the black gram that is majorly cultivated in the southern part of Asian countries. About 70% of world black gram production comes from India. Black gram is more prone to insect infestation and microorganisms resulting in deterioration of grain quality. These losses can be controlled by following appropriate storage method at farmer’s level. Eco-friendly, safe storage methods are demanded by the customers due to food safety, quality and environmental issues. Hermetic storage is a safe storage method, suitable for long term storage without usage of chemical pesticides. It creates an air tight environment to rapidly exterminate insect development and suppresses micro floral activity. A study was conducted to identify the suitable, cost effective storage method for safe storage of black gram at the farm level. Hermetic bags were made by using different combinations of gunny, polypropylene & storezo bags for the safe storage of black gram. The properties of packaging materials viz., thickness, and water vapour transmission rate significantly affected the quality parameters of the black gram stored in various bags. Moisture content, thousand grain mass, bulk density, insect emergence, and germination percentage of black gram stored in various bags were studied over a storage period of 12 months. Black gram stored in polypropylene and gunny bags was infested with pulse beetle by the third month of the storage period. But black gram stored in bags with hermetic bag as inner layer was not infested up to 12 months and could retain the grain quality.India is the primary origin of the black gram that is majorly cultivated in the southern part of Asian countries. About 70% of world black gram production comes from India. Black gram is more prone to insect infestation and microorganisms resulting in deterioration of grain quality. These losses can be controlled by following appropriate storage method at farmer’s level. Eco-friendly, safe storage methods are demanded by the customers due to food safety, quality and environmental issues. Hermetic storage is a safe storage method, suitable for long term storage without usage of chemical pesticides. It creates an air tight environment to rapidly exterminate insect development and suppresses micro floral activity. A study was conducted to identify the suitable, cost effective storage method for safe storage of black gram at the farm level. Hermetic bags were made by using different combinations of gunny, polypropylene & storezo bags for the safe storage of black gram. The properties of packaging materials viz., thickness, and water vapour transmission rate significantly affected the quality parameters of the black gram stored in various bags. Moisture content, thousand grain mass, bulk density, insect emergence, and germination percentage of black gram stored in various bags were studied over a storage period of 12 months. Black gram stored in polypropylene and gunny bags was infested with pulse beetle by the third month of the storage period. But black gram stored in bags with hermetic bag as inner layer was not infested up to 12 months and could retain the grain quality

Catalysts for long-life closed-cycle CO2 lasers

Long-life, closed-cycle operation of pulsed CO2 lasers requires catalytic CO-O2 recombination both to remove O2, which is formed by discharge-induced CO2 decomposition, and to regenerate CO2. Platinum metal on a tin (IV) oxide substrate (Pt/SnO2) has been found to be an effective catalyst for such recombination in the desired temperature range of 25 to 100 C. This paper presents a description of ongoing research at NASA-LaRC on Pt/SnO2 catalyzed CO-O2 recombination. Included are studies with rare-isotope gases since rare-isotope CO2 is desirable as a laser gas for enhanced atmospheric transmission. Results presented include: (1) achievement of 98% to 100% conversion of a stoichiometric mixture of CO and O2 to CO2 for 318 hours (greater than 1 x 10 to the 6th power seconds), continuous, at a catalyst temperature of 60 C, and (2) development of a technique verified in a 30-hour test, to prevent isotopic scrambling when CO-18 and O-18(2) are reacted in the presence of a common-isotope Pt/Sn O-16(2) catalyst

Reactivation of a tin oxide-containing catalyst

A method for the reactivation of a tin oxide-containing catalyst of a CO.sub.2 laser is provided. First, the catalyst is pretreated by a standard procedure. When the catalyst experiences diminished activity during usage, the heated zone surrounding the catalyst is raised to a temperature which is the operating temperature of the laser and 400.degree. C. for approximately one hour. The catalyst is exposed to the same laser gas mixture during this period. The temperature of the heated zone is then lowered to the operating temperature of the CO.sub.2 laser

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Bacterial and chemical analysis of Cardinal Creek flowing through the Ball State University campus from May to December, 1972

Detailed bacterial and chemical studies were conducted on Cardinal Creek, flowing through the Ball State University campus from May to December, 1972. Samples were collected from drain pipes flowing into the stream and also from the center of the stream between drain pipes.Results of the study show human waste materials are entering Cardinal Creek at the sampling site located behind the Ball State trailer courts. Forty-four percent of the time, ratios of fecal coliforms to fecal streptococci at this site were above 4.0 indicating human waste contamination.The presence of pathogens in the water is another clue to the quality of the surface water. Salmonella and Shigella are associated with gastro-intestinal diseases that may be spread by ingestion of water contaminated with these bacteria. Salmonella and Shigella were isolated on several occasions from the drain pipe behind the trailer courts. Salmonella paratyphi was found on the December 28 sampling date. It's presence in the creek shows human wastes are entering the stream.Chemical data, collected on December 28, indicate a heavy load of organic matter is entering Cardinal Creek at the Ball State trailer court drain pipe. Of all the sites sampled on this date, highest values for nitrogen and phosphorus and the lowest values for oxygen were found at the trailer court location.In conclusion, data collected in this study shows that water entering Cardinal Creek from the drain pipe located by the Ball State trailer courts, contains human fecal material. Measures should be taken to correct the situation.Thesis (M.S.

Characterization of intestinal invasion by Salmonella typhimurium and Salmonella dublin and effect of a mutation in the invH gene.

The relative levels of invasiveness of two bovine isolates each of Salmonella typhimurium and Salmonella dublin and of invH mutants of S. typhimurium were determined in MDCK and Int 407 cultured-cell assays and in bovine ileal loops. S. dublin was found to be significantly less invasive in cultured cells than S. typhimurium, but this difference was not observed in bovine intestines. The invH mutants exhibited a significant reduction in invasion in both cultured cells and bovine intestines. The invasive phenotypes of the strains were confirmed by fluorescent microscopy and scanning and transmission electron microscopy. The wild-type strains were observed in the laminae propriae of the intestinal villi, while in contrast the invH mutants were generally associated with the enterocyte layer. The degree of damage in the bovine ileum was related to the magnitude of the invasion. There was no difference in the amount of S. typhimurium or S. dublin recovered from the bovine ileum either with or without Peyer's patches 3 h after inoculation of the loop