Development of Metal Matrix Composites and Related Forming Techniques by Direct Recycling of Light Metals: A Review

In this contribution, researchers have provided a summary of the agricultural and industrial waste recoveries to be deployed as the composite reinforced materials. It covers the work of previous researchers related to this area and addressed the key challenge to overcome for further development and advancement. The major contributions of this work were a comprehensive review on a wide variety of Sever Plastic Deformation (SPD) techniques implementation in development of the waste materials based reinforced metal matrix composite. The waste materials can be derived from either industrial or natural sources. Also, it discusses the range of Metal Matrix Composites (MMCs) applications in engineering and related manufacturing techniques with further emphasized on the process parameters which directly determine the material properties. Some useful suggestions were proposed to the industrialists, academicians and scientists to further improve the performance aspect of Metal Matrix Composites (MMCs) for commercialization reason. Furthermore, industrial and natural waste enhancement materials have been strongly proposed because of their higher reinforced content particulates such as alumina (Al2O3) and silica (SiO2). Also, the mechanical and physical properties are directly influenced by the size, shape and weight-volume friction of the composites as same as the potential reactions between matrixes/reinforced materials interfac

Indoor air concentration from selective laser sintering 3d printer using Virgin Polyamide Nylon (PA12) Powder: a pilot study

Environmental emissions from additive manufacturing (AM) have attracted much attention recently. The capability in fabricating complex part make AM famous in developing prototype and product in various industries, especially in aerospace, medical, automotive, and manufacturing industries. However, the study on emission and exposure mainly focusses on the desktop type such as fused deposition modelling. This study investigates the emission and indoor concentration from powder bed fusion of selective laser sintering (SLS) technologies. Prior to the investigation, virgin PA12 has undergone characterization in terms of morphology, size and thermal analysis. Calibration block using virgin polyamide nylon (PA12) is selected to be printed in this study. Parameters such particulate matter size 2.5 μm (PM 2.5), total volatile organic compound (TVOC), carbon dioxide (CO2), formaldehyde, temperature and relative humidity (RH) are set to be monitored through real-time sampling of 8 hours based on Industry Code of Practice on Indoor Air Quality 2010 by Department Occupational Safety and Health (DOSH) Malaysia. Four phases of the printing process involve are background data, preprinting, during printing and post-printing. Based on the study it was found that PM 2.5 and CO2 exceed the acceptable limit recommended by DOSH Malaysia during the preparation of powder (preprinting) at 1218 ppm and 1070 μg/m3 respectively. Meanwhile TVOC concentration was influenced by the sintered powder temperature and recorded at 0.5 ppm. Temperature, relative humidity and formaldehyde were maintained throughout the SLS process. Mitigation strategies using mechanical ventilation and personal protective equipment (PPE) are recommended to be used to reduce the potential of occupational hazard to the operators

One-step electrochemical deposition of PolypyrroleChitosanIron oxide nanocomposite films for non-enzymatic glucose biosensor

One-step electrodeposition method of Polypyrrole–Chitosan–Iron oxide (Ppy–CS–Fe3O4) nanocomposite films (Ppy–CS–Fe3O4NP/ITO) has been developed for the fabrication of advanced composite coatings for biosensors applications. The FESEM and EDX results provide the evidence of successful incorporation of Fe3O4 into Ppy–CS molecules. The presence of Fe3O4 nanoparticles in the nanocomposite films was further confirmed by the XRD and XPS spectrums. The fabricated electrode Ppy–CS–Fe3O4 NP/ITO shows a fast amperometric response with high selectivity to detect glucose non-enzymatically with improved linearity (1–16 mM) and the detection limit of (234 μM) at a signal-to-noise ratio (S/N=3.0)

Elaboration and characterisation of novel low-cost adsorbents from grass-derived sulphonated lignin

AbstractThis study investigated the use of water-soluble sulphonated lignin (SL) extracted from grass, which has not been used before as a precursor of activated carbon (AC). Chemical activation of SL with three dehydrating salts (ZnCl2, KCl, Fe2(SO4)3·xH2O) at various salt concentrations (10%, 20%, 30%w/w), charring temperatures (600,700°C) and charring times (1,2h) has been carried out. The surface characteristics and removal efficiencies of cadmium, copper and zinc ions from aqueous solutions were affected by the activation conditions. The sulphonated lignin-based activated carbons (SLACs) with the highest specific surface area, total pore and micropore volume were produced at the lowest dehydrating salt concentration (10%w/w) and at 700°C and 2-h charring. These optimal sulphonated lignin-based ACs were named SLAC-ZC (optimal grass-derived SLAC activated by zinc chloride); SLAC-PC (optimal grass-derived SLAC activated by potassium chloride) and SLAC-FS (optimal grass-derived SLAC activated by ferric sulphate). The central composite design and surface response methodology of different SLACs characteristics showed that the optimal responses were achieved at the same operating conditions. These SLACs also achieved the highest removal efficiencies of Cd2+, Cu2+ and Zn2+ ions from aqueous solutions. The chemical activation had significantly increased the total porosity, microporosity and surface area of water-soluble SL. The activation mechanism depended on the used dehydrating salt where the porosity developed by the dehydration effect of ZnCl2, and by a series of hydrolysis and redox reactions for the other two salts. The results of this research demonstrated that water-soluble SL has a great potential as a novel precursor for the production of activated carbons

Population and fertility by age and sex for 195 countries and territories, 1950–2017: a systematic analysis for the Global Burden of Disease Study 2017

Background: Population estimates underpin demographic and epidemiological research and are used to track progress on numerous international indicators of health and development. To date, internationally available estimates of population and fertility, although useful, have not been produced with transparent and replicable methods and do not use standardised estimates of mortality. We present single-calendar year and single-year of age estimates of fertility and population by sex with standardised and replicable methods. Methods: We estimated population in 195 locations by single year of age and single calendar year from 1950 to 2017 with standardised and replicable methods. We based the estimates on the demographic balancing equation, with inputs of fertility, mortality, population, and migration data. Fertility data came from 7817 location-years of vital registration data, 429 surveys reporting complete birth histories, and 977 surveys and censuses reporting summary birth histories. We estimated age-specific fertility rates (ASFRs; the annual number of livebirths to women of a specified age group per 1000 women in that age group) by use of spatiotemporal Gaussian process regression and used the ASFRs to estimate total fertility rates (TFRs; the average number of children a woman would bear if she survived through the end of the reproductive age span [age 10–54 years] and experienced at each age a particular set of ASFRs observed in the year of interest). Because of sparse data, fertility at ages 10–14 years and 50–54 years was estimated from data on fertility in women aged 15–19 years and 45–49 years, through use of linear regression. Age-specific mortality data came from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 estimates. Data on population came from 1257 censuses and 761 population registry location-years and were adjusted for underenumeration and age misreporting with standard demographic methods. Migration was estimated with the GBD Bayesian demographic balancing model, after incorporating information about refugee migration into the model prior. Final population estimates used the cohort-component method of population projection, with inputs of fertility, mortality, and migration data. Population uncertainty was estimated by use of out-of-sample predictive validity testing. With these data, we estimated the trends in population by age and sex and in fertility by age between 1950 and 2017 in 195 countries and territories. Findings: From 1950 to 2017, TFRs decreased by 49\ub74% (95% uncertainty interval [UI] 46\ub74–52\ub70). The TFR decreased from 4\ub77 livebirths (4\ub75–4\ub79) to 2\ub74 livebirths (2\ub72–2\ub75), and the ASFR of mothers aged 10–19 years decreased from 37 livebirths (34–40) to 22 livebirths (19–24) per 1000 women. Despite reductions in the TFR, the global population has been increasing by an average of 83\ub78 million people per year since 1985. The global population increased by 197\ub72% (193\ub73–200\ub78) since 1950, from 2\ub76 billion (2\ub75–2\ub76) to 7\ub76 billion (7\ub74–7\ub79) people in 2017; much of this increase was in the proportion of the global population in south Asia and sub-Saharan Africa. The global annual rate of population growth increased between 1950 and 1964, when it peaked at 2\ub70%; this rate then remained nearly constant until 1970 and then decreased to 1\ub71% in 2017. Population growth rates in the southeast Asia, east Asia, and Oceania GBD super-region decreased from 2\ub75% in 1963 to 0\ub77% in 2017, whereas in sub-Saharan Africa, population growth rates were almost at the highest reported levels ever in 2017, when they were at 2\ub77%. The global average age increased from 26\ub76 years in 1950 to 32\ub71 years in 2017, and the proportion of the population that is of working age (age 15–64 years) increased from 59\ub79% to 65\ub73%. At the national level, the TFR decreased in all countries and territories between 1950 and 2017; in 2017, TFRs ranged from a low of 1\ub70 livebirths (95% UI 0\ub79–1\ub72) in Cyprus to a high of 7\ub71 livebirths (6\ub78–7\ub74) in Niger. The TFR under age 25 years (TFU25; number of livebirths expected by age 25 years for a hypothetical woman who survived the age group and was exposed to current ASFRs) in 2017 ranged from 0\ub708 livebirths (0\ub707–0\ub709) in South Korea to 2\ub74 livebirths (2\ub72–2\ub76) in Niger, and the TFR over age 30 years (TFO30; number of livebirths expected for a hypothetical woman ageing from 30 to 54 years who survived the age group and was exposed to current ASFRs) ranged from a low of 0\ub73 livebirths (0\ub73–0\ub74) in Puerto Rico to a high of 3\ub71 livebirths (3\ub70–3\ub72) in Niger. TFO30 was higher than TFU25 in 145 countries and territories in 2017. 33 countries had a negative population growth rate from 2010 to 2017, most of which were located in central, eastern, and western Europe, whereas population growth rates of more than 2\ub70% were seen in 33 of 46 countries in sub-Saharan Africa. In 2017, less than 65% of the national population was of working age in 12 of 34 high-income countries, and less than 50% of the national population was of working age in Mali, Chad, and Niger. Interpretation: Population trends create demographic dividends and headwinds (ie, economic benefits and detriments) that affect national economies and determine national planning needs. Although TFRs are decreasing, the global population continues to grow as mortality declines, with diverse patterns at the national level and across age groups. To our knowledge, this is the first study to provide transparent and replicable estimates of population and fertility, which can be used to inform decision making and to monitor progress. Funding: Bill & Melinda Gates Foundation

The Cholecystectomy As A Day Case (CAAD) Score: A Validated Score of Preoperative Predictors of Successful Day-Case Cholecystectomy Using the CholeS Data Set

Background Day-case surgery is associated with significant patient and cost benefits. However, only 43% of cholecystectomy patients are discharged home the same day. One hypothesis is day-case cholecystectomy rates, defined as patients discharged the same day as their operation, may be improved by better assessment of patients using standard preoperative variables. Methods Data were extracted from a prospectively collected data set of cholecystectomy patients from 166 UK and Irish hospitals (CholeS). Cholecystectomies performed as elective procedures were divided into main (75%) and validation (25%) data sets. Preoperative predictors were identified, and a risk score of failed day case was devised using multivariate logistic regression. Receiver operating curve analysis was used to validate the score in the validation data set. Results Of the 7426 elective cholecystectomies performed, 49% of these were discharged home the same day. Same-day discharge following cholecystectomy was less likely with older patients (OR 0.18, 95% CI 0.15–0.23), higher ASA scores (OR 0.19, 95% CI 0.15–0.23), complicated cholelithiasis (OR 0.38, 95% CI 0.31 to 0.48), male gender (OR 0.66, 95% CI 0.58–0.74), previous acute gallstone-related admissions (OR 0.54, 95% CI 0.48–0.60) and preoperative endoscopic intervention (OR 0.40, 95% CI 0.34–0.47). The CAAD score was developed using these variables. When applied to the validation subgroup, a CAAD score of ≤5 was associated with 80.8% successful day-case cholecystectomy compared with 19.2% associated with a CAAD score >5 (p < 0.001). Conclusions The CAAD score which utilises data readily available from clinic letters and electronic sources can predict same-day discharges following cholecystectomy

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