Organometallic vapor phase epitaxy of ZnSe with novel Zn and Se sources

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1994.Includes bibliographical references (leaves 176-195).by Jeung-Soo Huh.Ph.D

Assessing the viability of a grid-connected PV power plant in Mubi, Adamawa State, Nigeria

This paper is based on a techno-economic analysis and the environmental impact of a proposed 1 MW solar photovoltaic (PV) power plant at the main campus of the Federal Polytechnic Mubi (FPM) in north-eastern Nigeria. A photovoltaic power plant converts solar radiation into electricity that can be used as a source of electrical power to meet the daily energy requirements of homes, equipment, and all tertiary institutions. RETScreen Expert software was used to evaluate the techno-economic and environmental sustainability of installing a grid-connected PV power plant. The research results revealed that with an annual solar radiation of 5.74 kWh/m2/day, the maximum annual energy production was estimated to be 1,550.98 MWh. It was discovered that the maximum energy production in March was 146.89 MWh. The project’s profitability and economic sustainability were determined with a good internal rate of return (IRR) of 11.9% and a positive net present value (NPV) of $681,164. The proposed PV power plant has a simple payback period of 11.4 years. The maximum greenhouse gas (GHG) emission reduction is 670.9 tCO2, equivalent to 61.7 ha of forest-absorbing carbon emissions

A systematic literature review on the decarbonisation of the building sector—a case for Nigeria

The buildings sector is responsible for over 36% of total global end-use energy utilization and nearly 40% of the total indirect and direct carbon emissions. Low-carbon or zero-energy buildings remain the only option to lessen the sector’s energy consumption and CO2 emissions. The current systematic study examines low-carbon buildings under deep decarbonization scenarios in selected global south regions from 2010 to 2021. The study was channelled by the PRISMA (“Preferred Reporting Items for Systematic reviews and Meta-Analyses”) review process, which identified 29 related articles from Scopus, Web of Science., and Google Scholar databases. The identified critical drivers of emissions were population, gross domestic product, dwelling characteristics, and urbanization. The dwelling characteristics contributed about 12% and 27% to the total CO2 emissions in the selected regions. The population varies between 23% and 27% across the areas. Specific findings were made for inclusion in the Nigeria model while the general results were observed and further studies proposed. Total investment from the private and public sectors was identified as key to achieving the transition process of decarbonization in the building sector

Focused Ion Beam Fabrication

Contains reports on ten research projects.U.S. Army Research Office Contract DAAL03-88-K-0108Hughes Research Laboratories FellowshipSEMATECHCharles S. Draper Laboratory Contract DL-H-261827U.S. Army Research Office Contract DAAL03-87-K-0126IBM General Technologies DivisionIBM Research Divisio

Focused Ion Beam Fabrication

Contains reports on thirteen research projects and a list of publications.Defense Advanced Research Projects Agency/U.S. Army Research Office Contract DAAL03-88-K-0108National Science Foundation Grant ECS 89-21728MIT Lincoln Laboratory Innovative Research ProgramSEMATECH Contract 90-MC-503Micrion Contract M08774U.S. Army Research Office Contract DAAL03-87-K-0126IBM Corporatio

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

Comparison of Characteristics of a ZnO Gas Sensor Using a Low-Dimensional Carbon Allotrope

Owing to the increasing construction of new buildings, the increase in the emission of formaldehyde and volatile organic compounds, which are emitted as indoor air pollutants, is causing adverse effects on the human body, including life-threatening diseases such as cancer. A gas sensor was fabricated and used to measure and monitor this phenomenon. An alumina substrate with Au, Pt, and Zn layers formed on the electrode was used for the gas sensor fabrication, which was then classified into two types, A and B, representing the graphene spin coating before and after the heat treatment, respectively. Ultrasonication was performed in a 0.01 M aqueous solution, and the variation in the sensing accuracy of the target gas with the operating temperature and conditions was investigated. As a result, compared to the ZnO sensor showing excellent sensing characteristics at 350 °C, it exhibited excellent sensing characteristics even at a low temperature of 150 °C, 200 °C, and 250 °C

Determining Extremes for Future Precipitation in South Korea Based on RCP Scenarios Using Non-Parametric SPI

Historical, downscaled and projected data for six cities in South Korea were collected and analyzed using non-parametric Standardized Precipitation Index (SPI) across the Representative Concentration Pathways (RCPs) RCP4.5 and RCP8.5. SPI results were utilized in further analyses: intensity, decadal frequency, and temporal shifts. Non-parametric SPI was used as it produces more reliable results in terms of their statistical, spatial and temporal characteristics. RCP4.5 was taken to represent concentrations under the current emissions trajectory, while RCP8.5 represents the high-end scenario. Findings suggest that extreme precipitation events are more likely to increase in number than extreme drought across all timescales and RCPs. Variability was observed to increase when comparing SPI obtained from actual, measured and gridded precipitation. More extreme droughts are expected under RCP8.5 forcing as are the occurrence of multiyear droughts and extreme wet events relative to RCP4.5. A seasonal shift in extreme precipitation of up to 3 months earlier was observed. Generally, the period between 2080 and 2100 holds the highest probability to host extremely rare and persistent events

Gas Pressure Effect on Sand Collapse in Kinetic Zone of Lost-Foam Casting

Pressure of the kinetic zone is an essential factor for making defect-free castings in lost-foam casting process. The extremely high pressure causes many problems, such as reducing the melt velocity and inclusion of residual decomposition of the pattern in the castings, and very low pressure causes sand collapse. Therefore, the minimum gas pressure for preventing sand collapse is required. When the minimum gas pressure can be predicted, computer simulation becomes possible. Successful computer simulations can help reduce the number of trials and the lead time while designing new casting products. A preliminary sand experiment was conducted to predict the gas pressure and reduce the number of actual casting experiments. In this preliminary sand experiment, compressed air was used instead of gas in the kinetic zone. A new mathematical equation was proposed from the results of the preliminary sand experiment. The void ratio of the sand effect on the minimum gas pressure was included in the equation. An actual casting experiment was conducted by melting nodular cast iron to verify this equation. In the actual casting experiment, pressure of the kinetic zone in front of the metal tip was directly measured. The results obtained from the preliminary sand experiment and the actual casting experiment validated the equation

Formaldehyde Gas Sensing Characteristics of ZnO-TiO₂ Gas Sensors

Since the increase in the emission of various Volatiles Organic Compounds, gas and formaldehyde gas have had a harmful effect on the human body, and gas sensors that can measure those gases were fabricated in this study. After Pt coating was performed on the alumina substrate, Zn seed layers were fabricated. Nanostructures were formed through sonochemical synthesis by varying the ratio of ZnO and TiO2. Thereafter, the reactivity and recovery properties were compared and evaluated according to the concentrations of formaldehyde and toluene gas. The ZnO(99%)-TiO2(1%) gas sensor showed meaningful selectivity of about 40% or more at a concentration ranging from 5 to 20 ppm (high concentration) of formaldehyde and toluene gas, and showed a low selectivity of about 5% or more for a concentration ranging from 0.1 to 1 ppm (low concentration) of formaldehyde and toluene gas. This sensor can be optimized to have a meaningful selectivity of formaldehyde gas compared to other Volatiles Organic Compounds gases by optimizing the ZnO-TiO2 nanostructure