Development and characterisation of recycled carbon fibre based films/composites for thermoelectric applications

The increasing usage of carbon fibres in the aerospace, automotive and sports goods industries since the late 20th century has led to an end-of-life concern for the carbon fibre composites. An estimated 3000 tonnes of carbon fibre scrap are generated annually throughout the United States of America (USA) and Europe. The disposal of carbon fibre through incineration or landfill has been deemed infeasible and there have been environmental regulations that have imposed a ban on this material as it is non-biodegradable. For instance, in 1999, the European Union has enforced the Landfill Directive (1999/31/EC) that restricts the disposal of carbon fibre as a chemical waste. Therefore, there is a need for recycling these carbon composites that would not only save disposal cost, but more importantly, provides an avenue for reuse in a more sustainable manner. In the framework of reuse of recycled carbon fibre (RCF) and alternative product development to close the recycling loop of RCF, this research aims to develop RCF based thermoelectric films and composites. Electrodeposition method was used to synthesise n-type bismuth telluride (Bi2Te3) films on recycled carbon fibre (RCF) under different deposition conditions. Electrodeposition was studied using single parameter and multi-parameter optimisation. From the single parameter optimisation, it was observed that close to stoichiometric n-type Bi2Te3 fims have higher Seebeck coefficient (-12.99 μV/K). Multi-parameter optimisation was carried out using D-optimal model under response surface methodology (RSM) to design the experiment and optimise the following deposition parameters: deposition potential (V), deposition time (h), deposition temperature (°C) and electrolyte composition (molar concentration). The Seebeck coefficient of Bi2Te3 coated RCF using multi-parameter optimisation (-17.25 μV/K) was 33 % higher than the Seebeck coefficient obtained using single parameter optimisation (-12.99 μV/K). This research work also focused on the development of a low-cost effective RCF polymer thermoelectric composite. This study investigated the effect of the concentration of Bi2Te3 and Bi2S3 fillers respectively on the thermoelectric, morphology, structural and thermal stability of the RCF thermoelectric composites. The power factor of RCF thermoelectric composites was highest at 45 wt% of thermoelectric filler loading at 0.194 µWK-2m-1 and 0.094 µWK-2m-1 for RCF-Bi2Te3 and RCF-Bi2S3 respectively. In order to further improve the electrical conductivity and the subsequent thermoelectric properties of RCF composites, this study also investigated and studied the effect of varying concentration of multiwall carbon nanotubes (MWCNT) on the thermoelectric properties of RCF-Bi2Te3 and RCF-Bi2S3 composites. The optimum doping level of MWCNT for RCF-Bi2Te3 and RCF-Bi2S3 is 0.10 wt% and 0.15 wt% of MWCNTs, respectively. At optimum doping level, MWCNTs enhanced the power factors of RCF-Bi2Te3 and RCF-Bi2S3 composites by approximately 439 and 800%, respectively. The highest power factor obtained for MWCNT doped RCF-Bi2Te3 and RCF-Bi2S3 are 1.044 and 0.849 µWK-2m-1, respectively. Lastly, to enhance the crystallinity and electronic transport properties of the RCF composites, thermal annealing essentially a heat treatment that alters the physical and chemical properties of a semiconductor was studied. The optimum annealing temperature for Bi2Te3 and Bi2S3 particles within the RCF composites are 350 and 400 °C respectively. In addition to temperature, the optimum annealing time for both RCF-Bi2Te3 and RCF-Bi2S3 is 2 hours. At optimum annealing temperature and time, the power factor of RCF-Bi2Te3 and RCF-Bi2S3 composites are 7.836 and 2.551 µWK-2m-1 respectively. Both annealed RCF-Bi2Te3 and RCF-Bi2S3 composites depicted a 4000 and 2600% improvement in power factor as compared to the non-annealed counterparts

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 burden of disorders affecting the nervous system, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BackgroundDisorders affecting the nervous system are diverse and include neurodevelopmental disorders, late-life neurodegeneration, and newly emergent conditions, such as cognitive impairment following COVID-19. Previous publications from the Global Burden of Disease, Injuries, and Risk Factor Study estimated the burden of 15 neurological conditions in 2015 and 2016, but these analyses did not include neurodevelopmental disorders, as defined by the International Classification of Diseases (ICD)-11, or a subset of cases of congenital, neonatal, and infectious conditions that cause neurological damage. Here, we estimate nervous system health loss caused by 37 unique conditions and their associated risk factors globally, regionally, and nationally from 1990 to 2021.MethodsWe estimated mortality, prevalence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs), with corresponding 95% uncertainty intervals (UIs), by age and sex in 204 countries and territories, from 1990 to 2021. We included morbidity and deaths due to neurological conditions, for which health loss is directly due to damage to the CNS or peripheral nervous system. We also isolated neurological health loss from conditions for which nervous system morbidity is a consequence, but not the primary feature, including a subset of congenital conditions (ie, chromosomal anomalies and congenital birth defects), neonatal conditions (ie, jaundice, preterm birth, and sepsis), infectious diseases (ie, COVID-19, cystic echinococcosis, malaria, syphilis, and Zika virus disease), and diabetic neuropathy. By conducting a sequela-level analysis of the health outcomes for these conditions, only cases where nervous system damage occurred were included, and YLDs were recalculated to isolate the non-fatal burden directly attributable to nervous system health loss. A comorbidity correction was used to calculate total prevalence of all conditions that affect the nervous system combined.FindingsGlobally, the 37 conditions affecting the nervous system were collectively ranked as the leading group cause of DALYs in 2021 (443 million, 95% UI 378–521), affecting 3·40 billion (3·20–3·62) individuals (43·1%, 40·5–45·9 of the global population); global DALY counts attributed to these conditions increased by 18·2% (8·7–26·7) between 1990 and 2021. Age-standardised rates of deaths per 100 000 people attributed to these conditions decreased from 1990 to 2021 by 33·6% (27·6–38·8), and age-standardised rates of DALYs attributed to these conditions decreased by 27·0% (21·5–32·4). Age-standardised prevalence was almost stable, with a change of 1·5% (0·7–2·4). The ten conditions with the highest age-standardised DALYs in 2021 were stroke, neonatal encephalopathy, migraine, Alzheimer's disease and other dementias, diabetic neuropathy, meningitis, epilepsy, neurological complications due to preterm birth, autism spectrum disorder, and nervous system cancer.InterpretationAs the leading cause of overall disease burden in the world, with increasing global DALY counts, effective prevention, treatment, and rehabilitation strategies for disorders affecting the nervous system are needed

Development and characterisation of recycled carbon fibre based films/composites for thermoelectric applications

The increasing usage of carbon fibres in the aerospace, automotive and sports goods industries since the late 20th century has led to an end-of-life concern for the carbon fibre composites. An estimated 3000 tonnes of carbon fibre scrap are generated annually throughout the United States of America (USA) and Europe. The disposal of carbon fibre through incineration or landfill has been deemed infeasible and there have been environmental regulations that have imposed a ban on this material as it is non-biodegradable. For instance, in 1999, the European Union has enforced the Landfill Directive (1999/31/EC) that restricts the disposal of carbon fibre as a chemical waste. Therefore, there is a need for recycling these carbon composites that would not only save disposal cost, but more importantly, provides an avenue for reuse in a more sustainable manner. In the framework of reuse of recycled carbon fibre (RCF) and alternative product development to close the recycling loop of RCF, this research aims to develop RCF based thermoelectric films and composites. Electrodeposition method was used to synthesise n-type bismuth telluride (Bi2Te3) films on recycled carbon fibre (RCF) under different deposition conditions. Electrodeposition was studied using single parameter and multi-parameter optimisation. From the single parameter optimisation, it was observed that close to stoichiometric n-type Bi2Te3 fims have higher Seebeck coefficient (-12.99 μV/K). Multi-parameter optimisation was carried out using D-optimal model under response surface methodology (RSM) to design the experiment and optimise the following deposition parameters: deposition potential (V), deposition time (h), deposition temperature (°C) and electrolyte composition (molar concentration). The Seebeck coefficient of Bi2Te3 coated RCF using multi-parameter optimisation (-17.25 μV/K) was 33 % higher than the Seebeck coefficient obtained using single parameter optimisation (-12.99 μV/K). This research work also focused on the development of a low-cost effective RCF polymer thermoelectric composite. This study investigated the effect of the concentration of Bi2Te3 and Bi2S3 fillers respectively on the thermoelectric, morphology, structural and thermal stability of the RCF thermoelectric composites. The power factor of RCF thermoelectric composites was highest at 45 wt% of thermoelectric filler loading at 0.194 µWK-2m-1 and 0.094 µWK-2m-1 for RCF-Bi2Te3 and RCF-Bi2S3 respectively. In order to further improve the electrical conductivity and the subsequent thermoelectric properties of RCF composites, this study also investigated and studied the effect of varying concentration of multiwall carbon nanotubes (MWCNT) on the thermoelectric properties of RCF-Bi2Te3 and RCF-Bi2S3 composites. The optimum doping level of MWCNT for RCF-Bi2Te3 and RCF-Bi2S3 is 0.10 wt% and 0.15 wt% of MWCNTs, respectively. At optimum doping level, MWCNTs enhanced the power factors of RCF-Bi2Te3 and RCF-Bi2S3 composites by approximately 439 and 800%, respectively. The highest power factor obtained for MWCNT doped RCF-Bi2Te3 and RCF-Bi2S3 are 1.044 and 0.849 µWK-2m-1, respectively. Lastly, to enhance the crystallinity and electronic transport properties of the RCF composites, thermal annealing essentially a heat treatment that alters the physical and chemical properties of a semiconductor was studied. The optimum annealing temperature for Bi2Te3 and Bi2S3 particles within the RCF composites are 350 and 400 °C respectively. In addition to temperature, the optimum annealing time for both RCF-Bi2Te3 and RCF-Bi2S3 is 2 hours. At optimum annealing temperature and time, the power factor of RCF-Bi2Te3 and RCF-Bi2S3 composites are 7.836 and 2.551 µWK-2m-1 respectively. Both annealed RCF-Bi2Te3 and RCF-Bi2S3 composites depicted a 4000 and 2600% improvement in power factor as compared to the non-annealed counterparts

Optimisation of extractive desulfurization using Choline Chloride-based deep eutectic solvents

Sulfur in fuels is one of the main sources of pollution. Thus, the desulfurization of fuel (gasoline and diesel) is demanding for effective and alternative solutions. Deep eutectic solvents (DES) are gaining rapid interest in extraction processes due to their excellent properties as a solvent. In this study, extractive desulfurization (EDS) of model oil containing dibenzothiophene (DBT) as an organo-sulfur compound was carried using Choline Chloride acting as Hydrogen bond acceptor (HBA) and Propionic acid (Pr) as Hydrogen bond donor (HBD), respectively. Experiments are performed to study the effect of DES molar ratio, temperature and sonication time on DBT removal efficiency with molar ratios of 1:2 and 1:3 (HBA:HBD) using response surface methodology (RSM). DBT is quantitatively analysed using high-performance liquid chromatogram (HPLC) and Fourier transform infrared spectroscopy (FTIR) studies. The results showed high removal efficiency of 64.9% at a temperature of 37 °C, 10 min sonication; 1:3 ratio of ChCl/Pr and at a treat ratio of 1:3 model oil in a single stage extraction. This study will provide an alternative green solution which requires shorter reaction time and lower operating temperature as compared to conventional method i.e. hydrodesulfurization (HDS)

Cost effective thermoelectric composites from recycled carbon fibre: From waste to energy

Within the framework of recycling and reusing carbon fibre, this study focused on the fabrication of a thermoelectric composite encompassing recycled carbon fibre and two thermoelectric fillers (i) bismuth telluride and (ii) bismuth sulphide. This study investigated the effect of the concentration of bismuth telluride and bismuth sulphide fillers respectively on the thermoelectric, morphology, structural and thermal stability of the recycled carbon fibre thermoelectric composites. The optimum thermoelectric filler concentration is 45 wt% for both fillers, which resulted in a power factor of 0.194 ± 9.70 × 10−3 μWK−2m−1 and 0.0941 ± 4.71 × 10−3 μWK−2m−1 for recycled carbon fibre-bismuth telluride and recycled carbon fibre-bismuth sulphide composites respectively. This study exhibited the energy harvesting capabilities of recycled carbon fibre composites from low grade waste heat when coated with thermoelectric materials

Associations of autozygosity with a broad range of human phenotypes

Abstract: In many species, the offspring of related parents suffer reduced reproductive success, a phenomenon known as inbreeding depression. In humans, the importance of this effect has remained unclear, partly because reproduction between close relatives is both rare and frequently associated with confounding social factors. Here, using genomic inbreeding coefficients (FROH) for >1.4 million individuals, we show that FROH is significantly associated (p < 0.0005) with apparently deleterious changes in 32 out of 100 traits analysed. These changes are associated with runs of homozygosity (ROH), but not with common variant homozygosity, suggesting that genetic variants associated with inbreeding depression are predominantly rare. The effect on fertility is striking: FROH equivalent to the offspring of first cousins is associated with a 55% decrease [95% CI 44–66%] in the odds of having children. Finally, the effects of FROH are confirmed within full-sibling pairs, where the variation in FROH is independent of all environmental confounding