40 research outputs found
Laser processing of La61.4Al15.9Ni11.35Cu11.35 based functionally graded material bulk metallic glass
Bulk metallic glass (BMG) based on lanthanum is one of the BMG with exceptional glass-forming ability (GFA). The La61.4Al15.9Ni11.35Cu11.35 bulk metallic glasses were treated to a laser processing test in this experiment. The results showed that the best power, frequency, and speed ranges for laser processing of the La61.4Al15.9Ni11.35Cu11.35 BMG samples are 40 – 50 W, 160 – 240 kHz, and 200 – 400 mm/s, respectively. As a result, the current work was effective in producing the Lanthanum-based functionally graded material (FGM) BMG. The positive findings on the laser's microstructural or morphology, give a solid foundation for future advancement research on the La61.4Al15.9Ni11.35Cu11.35 BMG
Recommended from our members
An Outer Membrane Vesicle-Based Permeation Assay (OMPA) for Assessing Bacterial Bioavailability
When searching for new antibiotics against Gram-negative bacterial infections, a better understanding of the permeability across the cell envelope and tools to discriminate high from low bacterial bioavailability compounds are urgently needed. Inspired by the phospholipid vesicle-based permeation assay (PVPA), which is designed to predict non-facilitated permeation across phospholipid membranes, outer membrane vesicles (OMVs) of Escherichia coli either enriched or deficient of porins are employed to coat filter supports for predicting drug uptake across the complex cell envelope. OMVs and the obtained in vitro model are structurally and functionally characterized using cryo-TEM, SEM, CLSM, SAXS, and light scattering techniques. In vitro permeability, obtained from the membrane model for a set of nine antibiotics, correlates with reported in bacterio accumulation data and allows to discriminate high from low accumulating antibiotics. In contrast, the correlation of the same data set generated by liposome-based comparator membranes is poor. This better correlation of the OMV-derived membranes points to the importance of hydrophilic membrane components, such as lipopolysaccharides and porins, since those features are lacking in liposomal comparator membranes. This approach can offer in the future a high throughput screening tool with high predictive capacity or can help to identify compound- and bacteria-specific passive uptake pathways
Ossa cordis and os aorta in the one‐humped camel: Computed tomography, light microscopy and morphometric analysis
The present study describes the morphological characteristics of the camel heart Ossa cordis, and os aorta using computed tomography soft tissue window (CT) alongside 3D render volume reconstructions and light microscopy. The current study techniques demonstrated the Ossa cordis and os aorta in the cardiac window with more precision than the black and white (ghost), and angiography images. Transverse and sagittal CT images additionally demonstrated the presence of Ossa cordis and os aorta. This study is the first to record two small Ossa cordis sinistrum and one os aorta in the camel heart, in addition to the more commonly observed singular, large, os cordis dextrum. The os cordis dextrum was always located in the upper part of the interventricular septum, near to its junction with the atrium, forming an elongated rectangular shape when observed transversally. The wider cranial part was composed from bone, whereas the caudal aspect was narrow and contained both bone and cartilage. Light microscopy identified that the os cordis dextrum consisted of trabecular bone, marrow spaces, and hyaline cartilage. Two Ossa cordis sinistrum were detected on the left side of the heart, one in the right fibrous ring and another in the interventricular septum, microscopy showed that both contained only trabecular bone with osteocytes, osteoblasts, and osteoclasts. At the level of ascending aorta, there was also trabecular bone containing osteocytes, an os aorta
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
Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021
Background: Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. Methods: The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model—a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates—with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality—which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. Findings: The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2–100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1–290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1–211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4–48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3–37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7–9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. Interpretation: Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. Funding: Bill & Melinda Gates Foundation
Global, regional, and national levels of maternal mortality, 1990�2015: a systematic analysis for the Global Burden of Disease Study 2015
Background In transitioning from the Millennium Development Goal to the Sustainable Development Goal era, it is imperative to comprehensively assess progress toward reducing maternal mortality to identify areas of success, remaining challenges, and frame policy discussions. We aimed to quantify maternal mortality throughout the world by underlying cause and age from 1990 to 2015. Methods We estimated maternal mortality at the global, regional, and national levels from 1990 to 2015 for ages 10�54 years by systematically compiling and processing all available data sources from 186 of 195 countries and territories, 11 of which were analysed at the subnational level. We quantified eight underlying causes of maternal death and four timing categories, improving estimation methods since GBD 2013 for adult all-cause mortality, HIV-related maternal mortality, and late maternal death. Secondary analyses then allowed systematic examination of drivers of trends, including the relation between maternal mortality and coverage of specific reproductive health-care services as well as assessment of observed versus expected maternal mortality as a function of Socio-demographic Index (SDI), a summary indicator derived from measures of income per capita, educational attainment, and fertility. Findings Only ten countries achieved MDG 5, but 122 of 195 countries have already met SDG 3.1. Geographical disparities widened between 1990 and 2015 and, in 2015, 24 countries still had a maternal mortality ratio greater than 400. The proportion of all maternal deaths occurring in the bottom two SDI quintiles, where haemorrhage is the dominant cause of maternal death, increased from roughly 68 in 1990 to more than 80 in 2015. The middle SDI quintile improved the most from 1990 to 2015, but also has the most complicated causal profile. Maternal mortality in the highest SDI quintile is mostly due to other direct maternal disorders, indirect maternal disorders, and abortion, ectopic pregnancy, and/or miscarriage. Historical patterns suggest achievement of SDG 3.1 will require 91 coverage of one antenatal care visit, 78 of four antenatal care visits, 81 of in-facility delivery, and 87 of skilled birth attendance. Interpretation Several challenges to improving reproductive health lie ahead in the SDG era. Countries should establish or renew systems for collection and timely dissemination of health data; expand coverage and improve quality of family planning services, including access to contraception and safe abortion to address high adolescent fertility; invest in improving health system capacity, including coverage of routine reproductive health care and of more advanced obstetric care�including EmOC; adapt health systems and data collection systems to monitor and reverse the increase in indirect, other direct, and late maternal deaths, especially in high SDI locations; and examine their own performance with respect to their SDI level, using that information to formulate strategies to improve performance and ensure optimum reproductive health of their population. Funding Bill & Melinda Gates Foundation. © 2016 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY licens
Impact of ZnMn2O4/CdS nanocomposite on the structural, optical and dielectric characteristics of PMMA/PEO blend
Herein, polymethyl methacrylate (PMMA)/ polyethylene oxide (PEO) blend doped with nanocomposite (1 − x) ZnMn2O4/xCdS samples were prepared through two steps, the first comprising nanocomposite (1 − x) ZnMn2O4/xCdS samples synthesizing, while the second was the incorporation of nanocomposites into the blend matrix, and finally the films were obtained through the casting solution method. Various techniques, such as X-ray diffraction, scanning electron microscopy, diffused reflection and impedance spectroscopy were used to determine the change in the PMMA/PEO structure after the inclusion of the nanocomposites. The direct and indirect optical bandgap values for the PMMA/PEO blend decreased from 5.04 and 4.8 eV to 4.99 and 4.7 eV, respectively, as the blend doped with (1 − x) ZnMn2O4/xCdS samples. At 600 nm, the refractive index of the blend was raised from 1.37 to 1.53 as it doped with 0.9 ZnMn2O4/0.1CdS sample. The linear and nonlinear optical parameters grow with the insertion of (1-x)ZnMn2O4/xCdS nanocomposites into the PMMA/PEO blend. Variation of CdS in the doped nanocomposites affects slightly the linear and nonlinear optical parameters of the host blend. Blend containing 10 % CdS has the highest linear and nonlinear optical parameters as compared with other doped blends. All of the blends exhibited different shades of blue color, except for the blend that contained 10 % CdS, which displayed a violet color. The effect of doping on the dielectric properties of different blends was also explored. Blend with 20 % CdS has the highest energy density. This improvement implies the use of prepared blends in different optoelectronic, photocatalytic and storage device applications
Ameliorative effect of a novel enzymatic detoxifier against natural field levels of mycotoxins in the broiler chicken diet
Mycotoxins are considered hidden dangers that threaten the poultry industry globally because they suppress the immunity of birds, reduce their production, and increase their chance of being infected with diseases, which exposes the poultry industry to enormous economic losses. Therefore, this investigation aimed to assess the effectiveness of VemoZyme Detox®, a novel enzymatic detoxifier, in mitigating the detrimental consequences of mycotoxin contamination in broiler chickens. The experiment involved 10,000-day-old, Cobb 500 broiler chicks, which were allotted into two groups of 5000 birds each as follows: T1: received a control basal diet; and T2: birds were provided with a basal diet supplemented with VemoZyme Detox®. The birds underwent comprehensive monitoring, including evaluations of growth performance, blood parameters, mycotoxin levels, hepatic histopathological alterations, and litter bacteriological counts. Broilers receiving dietary VemoZyme Detox® exhibited significant improvements in various aspects, including growth performance, reduced mortality rates, and more favorable feed conversion ratios. Moreover, the enzymatic supplement played a protective role in maintaining hepatic and renal health, as evidenced by reductions in blood aspartate aminotransferase (AST), alanine aminotransferase (ALT), uric acid, and creatinine. Importantly, although there was no significant difference in mycotoxin levels (zearalenone, fumonisin B1, ochratoxin A, aflatoxin B1) within the feed, VemoZyme Detox® had a significant impact on decreasing mycotoxin levels, particularly those of zearalenone and fumonisin B1. Hepatic histological examinations also revealed healthier conditions in T2, and positive impacts extended to litter samples, as indicated by reduced counts of Clostridium perfringens (C. perfringens) and Escherichia coli (E. coli) counts. In conclusion, the use of an enzymatic detoxifier is a promising method for counteracting the negative impacts of mycotoxin contamination in broilers. The results underscore the substantial potential of enzymatic detoxifiers for ensuring the health and productivity of broilers, opening new avenues for safer poultry production
Optical and structure properties of CH
Methylammonium lead iodide doped with cesium (MA1–xCsxPbI3, x = 0, 0.03, 0.05, 0.1) thin films were prepared with and without chlorobenzene (CB). X-ray diffraction analysis applying the Rietveld refinement method is carried out, and the effect of Cs and CB on the lattice parameters, crystallite size, lattice microstrain, and dislocation density of the formed films is examined. SEM images with different magnifications are used to investigate the films' morphology and homogeneity. Adding CB reduced the number of pinholes and the grain size in the formed films. The UV-Vis-NIR spectroscopy technique was used to investigate the transmittance, reflectance, and absorbance spectra for Cs doped MAPbI3 with and without CB. In general, for Cs doped films, adding CB increases the film transmittance. The refractive index of 3% Cs doped film has the highest value among the films without CB. The optical bandgap, refractive index, and optical conductivity for films with CB are higher than those without CB for all doping Cs values. The influence of Cs doping and CB addition on the photoluminescence (PL) emitted spectra was studied using a PL set-up with a laser source of 532 nm