Thermal performance enhancement of a flat plate solar collector using hybrid nanofluid

Covalent Functionalized-Multi wall carbon nanotubes (CF-MWCNTs) and Covalent Functionalized-graphene nanoplatelets (CF-GNPs) with hexagonal boron nitride (h-BN) were suspended in distilled water to prepare the hybrid nanofluids as working fluids inside the Flat Plate Solar Collector (FPSC). Different concentrations of the hybrid nanoparticles were considered and Tween-80 (Tw-80) was used as a surfactant. The stability and thermophysical properties were tested using different measurement tools. The structural and morphological properties were examined using FTIR, XRD, UV–vis spectrometry, HRTEM, FESEM, and EDX. The thermal efficiency of FPSC were tested under different volumetric flow rates (2 L/min, 3 L/min, and 4 L/min), whereas the efficiency of the collector was determined based on ASHRAE standard 93-2010. As a result, the most thermal-efficient solar collector improved up to 85% with hybrid nanofluid as the absorption medium at 4 L/min flow rate. Increment in nanoparticles’ concentrations enhanced thermal energy gain and resulted in higher fluid outlet temperature

Simultaneous determination of time-dependent coefficients and heat source

This article presents a numerical solution to the inverse problems of simultaneous determination of the time-dependent coefficients and the source term in the parabolic heat equation subject to overspecified conditions of integral type. The ill-posed problems are numerically discretized using the finite-difference method. The resulting system of nonlinear equations is solved numerically using the MATLAB toolbox routine lsqnonlin applied to minimizing the nonlinear Tikhonov regularization functional subject to simple physical bounds on the variables. Numerical examples are presented to illustrate the accuracy and stability of the solution

The global burden of cancer attributable to risk factors, 2010–19: a systematic analysis for the Global Burden of Disease Study 2019

BACKGROUND: Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. METHODS: The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk–outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. FINDINGS: Globally, in 2019, the risk factors included in this analysis accounted for 4·45 million (95% uncertainty interval 4·01–4·94) deaths and 105 million (95·0–116) DALYs for both sexes combined, representing 44·4% (41·3–48·4) of all cancer deaths and 42·0% (39·1–45·6) of all DALYs. There were 2·88 million (2·60–3·18) risk-attributable cancer deaths in males (50·6% [47·8–54·1] of all male cancer deaths) and 1·58 million (1·36–1·84) risk-attributable cancer deaths in females (36·3% [32·5–41·3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20·4% (12·6–28·4) and DALYs by 16·8% (8·8–25·0), with the greatest percentage increase in metabolic risks (34·7% [27·9–42·8] and 33·3% [25·8–42·0]). INTERPRETATION: The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden

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

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

The influence of covalent and non-covalent functionalization of GNP based nanofluids on its thermophysical, rheological and suspension stability properties

Covalent functionalization (CF-GNPs) and non-covalent functionalization (NCF-GNPs) approaches were applied to prepare graphene nanoplatelets (GNPs). The impact of using four surfactants (SDS, CTAB, Tween-80, and Triton X-100) was studied with four test times (15, 30, 60, and 90 min) and four weight concentrations. The stable thermal conductivity and viscosity were measured as a function of temperature. Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), X-ray diffraction (XRD) and Raman spectroscopy verified the fundamental efficient and stable CF. Several techniques, such as dispersion of particle size, FESEM, FETEM, EDX, zeta potential, and UV-vis spectrophotometry, were employed to characterize both the dispersion stability and morphology of functionalized materials. At ultrasonic test time, the highest stability of nanofluids was achieved at 60 min. As a result, the thermal conductivity displayed by CF-GNPs was higher than NCF-GNPs and distilled water. In conclusion, the improvement in thermal conductivity and stability displayed by CF-GNPs was higher than those of NCF-GNPs, while the lowest viscosity was 8% higher than distilled water, and the best thermal conductivity improvement was recorded at 29.2%

Investigation of stability, dispersion, and thermal conductivity of functionalized multi-walled carbon nanotube based nanofluid:5th UTP-UMP-UAF Symposium on Energy Systems 2019, SES 2019

In the attempt of preparing multi-walled carbon nanotube (MWCNTs), covalent functionalisation (CF-MWCNTs) were applied. The stable thermal conductivity was measured as a function of temperature. A number of techniques, such as FTIR, FESEM and UV-vis spectrophotometer were employed to characterise both dispersion stability and morphology of functionalised materials. By using ultrasonic test time, the highest stability of nanofluids was achieved at 60 minutes. As a result, the thermal conductivity displayed by CF-MWCNTs was higher than distilled water. In conclusion, improvement in thermal conductivity and stability displayed by CF-MWCNTs was higher, while the best thermal conductivity improvement was recorded at 31%. © 2020 Published under licence by IOP Publishing Ltd

The proximal tibia anthropometry in adult Nigerians: Correlation to tibial components of total knee replacement and equations for estimation of its dimensions

Background: The knee joint is commonly affected by osteoarthritis. Total Knee Replacement (TKR) is usually considered for knee osteoarthritis after failure of conservative management. The total knee prostheses used during this procedure are fashioned from bony dimensions of Westerners.Objective: This study compared some of the available tibial baseplate with the proximal tibiae dimension of Nigerians. It also provided equations that can be used to estimate dimensions of different parts of proximal tibia.Design: This was a prospective descriptive study.Methods: Fifty four matured tibiae, comprising 23 right and 31 left bones were measured. Ten parameters were measured and documented. Dimensions of proximal tibia bones from other regions of the world were retrieved from published articles. The dimensions of tibial baseplates were extracted from product monographs. Analyses were done with Microsoft excel 2010 (Microsoft Corporation, Redmond, Washington, United States) and STATA version 13 (Stata Corp, Texas. USA). Statistical significance was set at p ≤ 0.05.Results: There were no significant differences between the left and right tibiae. The average proximal tibia dimension differs from between racial groups. The average aspect ratio calculated was 1.51 ± 0.11. Three of the four implants have sizes that were far larger than the tibiae dimensions, with increment in sizes that were far steep compared to the dimensions of the proximal tibiae. There wasa mismatch of aspect ratio of the tibiae and those of the tibial baseplates. Equation to estimate the anteroposterior dimension for each tibia condyle was generated and tested on published values.Conclusion: This study provided equations that can be used to estimate the anteroposterior dimensions of tibial plateau, the medial and the lateral condyles with the estimated values within ±5mm of the actual value. This can be used as part of pre-operative planning. It also provided data that can be considered in the designing of a suitable tibial baseplate component of total knee prosthesis for Nigerians. Key words: Total knee replacement, Pre-operative, Planning, Proximal tibia, Tibia bone fixation, Nigerians, Africans, Anthropometry, Knee prosthesi

Proximal femoral bone morphological measurements: Relevance in orthopaedic and forensic medicine

Background: Numerous surgical procedures are performed on and around the proximal femur to restore the anatomy and maintain the function of the limb. Hip joint prostheses and surgical implants that are usually used for these procedures were manufactured using dimensions from other populations.Objective: This study documented the anatomic dimensions of proximal femur of Nigerians, devised various equations through regression analysis for pre-operative estimation of certain parts of the proximal femur and for use in forensic medicine. This study also correlated the dimensions of the proximal femur with different surgical implants available.Methods: A total of 56 adult dry femoral bones were studied. Parameters measured were Maximum Femoral Length (MFL), length of the femur between the tip of the greater trochanter and the lateral condyle (termed Trochanteric Length (TL) of the femur), Femoral Neck Length (FNL), Femoral Neck Diameter (FND), Femoral Neck Axial Length (FNAL), Femoral Neck Shaft Angle (FNSA) and Proximal Femoral Shaft Diameter (PFSD). The monographs of surgical implants were obtained. Analyses were done with Microsoft excel 2010 (Microsoft Corporation, Redmond, Washington, United States) and STATA version 13 (StataCorp, Texas. USA). Statistical significance was set at p ≤ 0.05.Results: The average measured values of the parameters were: MFL was 47.9cm, TL was 45.8cm, FNL was 22.9mm, FNAL was 96.9mm, FND was 30.3mm, PFSD was 28.4mm and FNSA was 130.8°. Regression analysis revealed significant statistical relationship between the lengths of femur and other parameters measured; with equations that can be used in clinical settings to estimate certain parameters: MFL = 2.5 + TL; range ± 1cm. FND = 6 + 0.05*TL(mm); range ± 5mm; FNAL = 5 + 0.206*TL(mm); range ± 15mm. TL was used in the equations because it can be measured easily in clinical settings. In forensic medicine, MFL can be estimated from the FND and FNAL, using the equations: MFL = 30.5 + 0.18*FNAL and MFL = 42.14 + 0.19*FND.Conclusion: This study has provided data of the dimensions of proximal femur in Nigerians. Various equations generated from this study will be useful in pre-operative planning, clinical settings and forensic medicines

A formulation of kinematic constraints imposed by kinematic pairs using relative pose in vector form

This paper presents a formulation that expresses kinematic pairs in form of holonomic constraints as functions of a measure of the relative position and orientation of the connected bodies expressed in vector form. While formulating the relative position measure is straightforward, expressing a suitable measure of the relative orientation requires some care. The problem is addressed by computing the Euler vector of the product of the actual and prescribed relative rotation matrices. By arbitrarily combining the error measures in up to six independent equations, a general family of holonomic rheonomic constraints can be formulated. The relative motion between the bodies can be constrained or specified component-wise, respectively, resulting in scleronomic or rheonomic constraints. The proposed formulation is implemented in a free, general-purpose multibody solver; numerical applications to generic mechanical and aerospace problems are presented