297 research outputs found
Performance of transition metal-doped CaCO3 during cyclic CO2 capture-and-release in low-pressure H2O vapour and H2O plasma
The effects of transition metal doping of calcium carbonate on the subsequent performance of the material during CO2 release and recapture have been evaluated for calcination under low-pressure (~0.1 mbar) water vapour and water plasma conditions. The initial samples were prepared by precipitation method from analytical grade carbonate, calcium and transition metal (Fe, Co, Zn, Cu and Ni) containing precursors. The release-recapture properties of the sorbents were monitored over five cycles involving calcination at 1200 K and carbonation at 825 K. The most noteworthy effects were observed for the Zn-doped samples, which exhibited rapid CO2 recapture. Calcination in H2O plasma was tested to evaluate the potential for in-situ material processing as a means to counteract material degradation. The impact of plasma exposure during calcination on the looping performance was mixed and dependent on the specific sample composition. The performance of the Zn-doped CaCO3 was consistently improved by plasma calcination, yielding high uptake and better retention of carrying capacity over the five cycles. All samples exhibited a deterioration in carrying capacity over repeated cycles. The Zn-doped samples also performed best in this respect (least loss of carrying capacity). The beneficial effects of Zn-doping were dependent on the Zn-content of the precursor solutions used for material synthesis.</p
Identifying the effects of land use change on sediment export: Integrating sediment source and sediment delivery in the Qiantang River Basin, China
Dramatic land use change caused by the rapid economic development in China has impacted the sediment export dynamics in the large basin. However, how land use change affects sediment export is still poorly understood. This study provided an integrated analysis of the relationships in a “three-level” chain linked as follows: “land use change → changes in sediment source and sediment delivery → sediment export change” for a better understanding. It used the InVEST sediment delivery ratio (SDR) model to analyze the Qiantang River Basin (4.27 ∗ 104 km2), China. Sediment export change was examined from the two perspectives: the effects of land use change on sediment source and on sediment delivery. Correlations between changes in individual land use types and changes in sediment source and sediment delivery were identified. The results indicated that sediment export reduced from 1.69 t ha−1 yr−1 in 1990 to 1.22 t ha−1 yr−1 in 2015 because of the decreased sediment source and a weakened sediment delivery function. In the study area, the conversions of cropland to urban land (urbanization) and bare land to forestland (afforestation) were found to make the major contributions to reductions in soil loss and SDR, respectively. Furthermore, soil loss change resulted in the decreases in total value of sediment export and SDR change caused a large-scale spatial change in sediment export. Our hotspot analysis revealed that the Wuxi River watershed should be targeted for priority conservation to optimize land use/cover for reducing sediment export. This study demonstrates the benefits of taking a comprehensive approach to analyze the processes associated with sediment export change. These allow to improve sediment management and promote aquatic ecosystem health by providing specific future land use recommendations, aimed at source treatment and delivery interception
Going Ballistic: Graphene Hot Electron Transistors
This paper reviews the experimental and theoretical state of the art in
ballistic hot electron transistors that utilize two-dimensional base contacts
made from graphene, i.e. graphene base transistors (GBTs). Early performance
predictions that indicated potential for THz operation still hold true today,
even with improved models that take non-idealities into account. Experimental
results clearly demonstrate the basic functionality, with on/off current
switching over several orders of magnitude, but further developments are
required to exploit the full potential of the GBT device family. In particular,
interfaces between graphene and semiconductors or dielectrics are far from
perfect and thus limit experimental device integrity, reliability and
performance
Partitioning the impacts of land use/land cover change and climate variability on water supply over the source region of the Blue Nile Basin
Water plays a vital role in sustaining the natural functioning of the entire ecosystem that supports life on Earth. It plays key roles in the well‐being of society in numerous ways. However, climate variability and land use land cover (LULC) change have caused spatiotemporal water supply variation. Disentangling the effects of climate variability from LULC change on water supply is crucial for sustainable water resource management. The main purpose of this study is, therefore, to disentangle the relative contribution of LULC change and climate variability to the overall average annual water supply variation. Residual trends analysis combined with Integrated Valuation of Environmental Services and Tradeoffs (InVEST) annual water yield model was adopted to perform simulations and disentangle the relative impacts of climate variability and LULC change. Ground and satellite data were used in this study. The study area has experienced a significant increasing wetness trend and significant LULC dynamics between 2003 and 2017. As a result, an increasing water supply was observed due to the joint effects of climate variability and LULC change in the watershed (203 mm). The contribution of climate variability was 94%, whereas LULC contributes only 6% from 2003 to 2017. Climate variability negatively led to water supply variation while LULC change contributed positively from 2010 to 2017. Although the ongoing soil and water conservation (SWC) practices improved vegetation cover and water retention of the watershed, climate variability is the main driver of water supply variation. Therefore, SWC practices should incorporate ecosystem‐based climate change adaptation strategies and scale up to community‐based integrated watershed management to sustain water supply
Prevalence and Associated Factors of Sensorineural Hearing Impairment Among Patients with T2DM in Amhara Region, Northwest Ethiopia, 2022: A Multi-Centered Cross-Sectional Study
Dereje Esubalew,1 Mihret Melese,2 Melese Belete,3 Adugnaw Ambelu,2 Bezawit Mulat,2 Tadegew Adane,4 Wubet Tazeb Wondie,5 Mengistie Diress2 1Department of Human Physiology, College of Medicine and Health Sciences, Ambo University, Ambo, Ethiopia; 2Department of Human Physiology, School of Medicine, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia; 3Department of Human Physiology, College of Medicine and Health Sciences, Wollo University, Dessie, Ethiopia; 4Department of Human Physiology, School of Medicine, College of Medicine and Health Sciences, Debre Markos University, Debre Markos, Ethiopia; 5Department of Pediatrics and Child Health Nursing, College of Medicine and Health Sciences, Ambo University, Ambo, EthiopiaCorrespondence: Dereje Esubalew, Tel +251942868674, Email [email protected]: Generally, people with type 2 diabetes mellitus in various countries experience a significant rate of sensorineural hearing impairment. Nonetheless, there is scant evidence of sensorineural hearing impairment among type 2 diabetes mellitus patients in Northwest Ethiopian. Therefore, the objective of this study was to evaluate the occurrence rate and contributing factors of sensorineural hearing impairment in type 2 diabetics at comprehensive and specialized referral hospitals in Northwest Ethiopia.Methods: A facility-based cross-sectional study design was carried out from May 3, 2022, to June 14, 2022, on 846 study participants in Ethiopia, with a response rate of 99.65%. The research subjects were chosen by simple random sampling techniques. Data was gathered by using audiometric measurements and structured interview-administered questionnaires and then entered into EPI data version 4.6. Finally, it was exported to STATA 14 for analysis. Binary logistic regression, chi-square test, and odds ratio were done to verify the assumptions and degree of association. Ultimately, factors exhibiting a p-value < 0.05 with a 95% CI were regarded as significant predictors of hearing impairment.Results: The magnitude of sensorineural hearing impairment in this investigation was 50.49% (95% CI: 45.67%, 55.26%). Factors significantly associated with sensorineural hearing impairment were age (AOR=1.10, 95% CI: 1.07, 1.14), hyperlipidemia (AOR=2.86, 95% CI: 1.05, 7.82), duration of diabetes (AOR=2.26, 95% CI: 1.26, 4.06), hypertension (AOR=1.94, 95% CI: 1.02, 3.69) and regular physical exercise (AOR=0.25, 95% CI: 0.09, 0.68).Conclusions and Recommendations: In this study, relatively high rates of sensorineural hearing impairment were observed. Stakeholders should establish routine hearing screening, and participants will advise to incorporate regular physical exercise into their routines.Keywords: hearing loss, impairment, audiometer, diabetes, Ethiopi
Developing logistic software platforms: e-market place, a case study
This paper describes a framework for software development with emphasis on logistics platforms. Specifically, a case study is presented regarding the Logport program in Colombia’s Caribbean coast. The software development is based on the merging of modeling, design, and agile development techniques aimed towards software production. The agile methodologies discussed herein include Scrum, XP, and Crystal among others, and specific verification and validation aspects of CMMI 1.3 are evaluated. Furthermore, the integration of emerging technologies including elastic computing in cloud computing that allows scaled integration, security, load balancing, process speed, and high concurrency among other features are discussed. Finally, the proposed solutions cover actual and emergent needs in a B2B or B2C electronic commerce dynamic environment where suppliers and clients offer and demand transport, storage, and customs services. In this environment, their goal is to ensure there is added value to their logistics processes starting at the inputs and all the way to the outputs of the commercial business processes. Colombia’s Caribbean region is one such multimodal and multiport environment in which there is constant demand for low cost, time and storage optimization, and customs reliability for the businesspersons of this region, which serves as a Hub for the American Caribbean
Identification of patterns of transmission of Salmonella within swine production systems using pulsed field gel electrophoresis (PFGE) and repetitive sequence polymerase chain reaction (REP-PCR): a quantitative analysis
Pulsed field gel e lectrophoresis (PFGE) using 3 enzymes (Spe I, Xba I, Avr II) and repetitive sequence polymerase chain reaction (REP-PCR) with 3 primers (BOX, ERIC, REP) were compared with respect to their validity as a method for identifying transmission of Salmonella on swine farms. Sixty-eight isolates of Salmonella were obtained from feces of swine, cats, mice, and birds, insect body parts, water and floor samples, and boot scrapings collected on 9 swine farms in Illinois USA. Genetic distances between isolates were calculated using the Dice matching coefficient. Cluster analysis of distance matrices was conducted using the UPGMA algorithm
Variations in seasonal solar insolation are associated with a history of suicide attempts in bipolar I disorder
Background: Bipolar disorder is associated with circadian disruption and a high risk of suicidal behavior. In a previous exploratory study of patients with bipolar I disorder, we found that a history of suicide attempts was associated with differences between winter and summer levels of solar insolation. The purpose of this study was to confirm this finding using international data from 42% more collection sites and 25% more countries. Methods: Data analyzed were from 71 prior and new collection sites in 40 countries at a wide range of latitudes. The analysis included 4876 patients with bipolar I disorder, 45% more data than previously analyzed. Of the patients, 1496 (30.7%) had a history of suicide attempt. Solar insolation data, the amount of the sun’s electromagnetic energy striking the surface of the earth, was obtained for each onset location (479 locations in 64 countries). Results: This analysis confirmed the results of the exploratory study with the same best model and slightly better statistical significance. There was a significant inverse association between a history of suicide attempts and the ratio of mean winter insolation to mean summer insolation (mean winter insolation/mean summer insolation). This ratio is largest near the equator which has little change in solar insolation over the year, and smallest near the poles where the winter insolation is very small compared to the summer insolation. Other variables in the model associated with an increased risk of suicide attempts were a history of alcohol or substance abuse, female gender, and younger birth cohort. The winter/summer insolation ratio was also replaced with the ratio of minimum mean monthly insolation to the maximum mean monthly insolation to accommodate insolation patterns in the tropics, and nearly identical results were found. All estimated coefficients were significant at p < 0.01. Conclusion: A large change in solar insolation, both between winter and summer and between the minimum and maximum monthly values, may increase the risk of suicide attempts in bipolar I disorder. With frequent circadian rhythm dysfunction and suicidal behavior in bipolar disorder, greater understanding of the optimal roles of daylight and electric lighting in circadian entrainment is needed
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