Microstructural refinement and corrosion resistance improvement of heat-treated A356 alloy processed by equal channel angular pressing

The microstructure refinement, hardness and corrosion resistance of heat-treated A356 aluminium alloy processed by equal-channel angular pressing (ECAP) were investigated. ECAP was carried out at room temperature using a mold, with a channel angle of 120° via route A. Results of the investigation confirm that the flaky coarse silicon particles were effectively fragmented from 4.22 to 0.761 μm and the grain size reduced from 171 to 40 μm after four passes of heat-treated as-cast using ECAP process. ECAP processing increases the hardness of heat-treated as-cast alloy from 61 Hv to 125 HV after four passes. Heat-treated A356 alloy shows enhanced corrosion resistance from 0.0424 to 0.00149 mmy-1, after four passes. In this research, ECAP processing has been shown to improve the hardness and corrosion resistance of as-cast A356 alloy

Effect of equal channel angular pressing processing routes on corrosion resistance and hardness of heat treated A356 alloy

Equal channel angular pressing (ECAP) via routes A and Bc was used to process heat treated A356 alloy. The samples produced a range of microstructures in order to investigate the effect of straining on its corrosion behavior in 3.5 wt. % NaCl solution and hardness. The ECAP was conducted at room temperature in a mold with channel angle of 120°. The results show that brittle coarse silicon particles were effectively fragmented into smaller size in the Al-rich matrix after the processing. The hardness and corrosion resistance test showed improvement after T5 and T6 heat treatment, preferably to T6 due to wholly changed in silicon particles morphology than T5. The hardness increased with ECAP processing from 60.66 Hv to 1133.47, 124.91 Hv after three passes route Bc and four passes route A, respectively. The evaluation of corrosion resistance of the alloy showed improvement from 0.0424 to 0.00173, 0.00149 mmy-1 after three passes route Bc and four passes route A, respectively. In this research, both strength and corrosion resistance are improved by ECAP processing of A356 alloy using both routes

Changes in impacts of climate extremes: human systems and ecosystems

In this chapter, two different types of impacts on human and ecological systems are examined: (i) impacts of extreme weather and climate events; and (ii) extreme impacts triggered by less-than-extreme weather or climate events (in combination with non-climatic factors, such as high exposure and/or vulnerability). Where data are available, impacts are examined from sectoral and regional perspectives.Peer Reviewe

Study of angular cutting conditions using multiple scratch tests onto low carbon steel: An experimental-numerical approach

Multiple parallel scratches are often analyzed to understand the material removal mechanisms due to abrasion. However, successive scratches with different orientations may represent better the conditions found in machining processes, such as honing and belt finishing. The objective of this work was to analyze the cutting forces and the phenomena of material removal due to abrasion, arising from angular scratches in low carbon steel. Experimental and numerical techniques were considered. In both, analyses considered the presence of an initial set of parallel scratches, followed by a second set of scratches with different orientations (10, 20 or 30°) with respect to the previous one. The cutting action was performed by a tool representing an abrasive particle, which had a cono-spherical geometry with 235μm tip radius and 30° apex angle. The cutting settings were: 50m/min scratch velocity and 100μm depth of cut. In the experimental part, scratches were conducted using a shaper machine tool equipped with a tungsten carbide (WC-Co) stylus. Tests were conducted on a Kistler platform, which allowed force measurement. Surfaces were later analyzed with an optical profilometer. The numerical simulations considered a ductile damage model with element deletion to provide the material removal during the scratches. Experimental and numerical results showed that the angle affects the cutting forces, especially when one scratch crosses a previously scratched region. The 20° case was the most critical, especially in terms of the cutting forces, due to the accentuated material strain-hardening for this condition. Likewise, this fact was corroborated by numerical results, which indicated a higher energy necessary to plastic deformation, and a reduced material removal at 20°

Harmonic assessment based adjusted current total harmonic distortion

Power systems suffer from harmonic distortion and extra ohmic losses associated with them. Moreover, all harmonic frequencies are mostly assumed to have the same effect on the system losses. However, the frequency-dependency of the resistances should be taken into account, so that the apparent power and the power factor have to considerably reflect power losses under nonsinusoidal conditions. In this paper, the difference between unweighted and weighted non-sinusoidal losses, is addressed. A new harmonic-adjusted total harmonic distortion definition is proposed for both voltage and current. Besides, a new formula that relates the proposed harmonic-adjusted total harmonic distortion and a generalised harmonic derating factor definition of the frequency dependent losses of the power transmission and distribution equipment, is derived. An optimal C-type passive filter design for harmonic mitigation and power factor correction based on the minimisation of the proposed harmonic-adjusted total harmonic distortion for a balanced nonsinusoidal system is introduced. A comparative study of the proposed filter design based on the new harmonic-adjusted definition, and a conventional filter design based on standard total harmonic distortion definition, is presented

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 effects of group versus single housing on home cage behaviour in two strains of laboratory mice

Studying the behavioural patterns of animals in their house may help to understand their needs, but there has been a little investigation of home-cage behaviours in commonly used inbred strains of mice such as C57BL/6 and DBA/2. Therefore, understanding behavioural patterns in these mice is important for neuroscience research. For the first time, this experiment was carried out to investigate the long-term effects of housing conditions (single vs. group) on home cage behaviour of C57BL/6 and DBA/2 mice, in order to reveal differences between C57BL/6 and DBA/2 in home-cage behaviours and in response to single-housing. Sixty-four mice (32 mice/strain) were housed either singly (SH) (n= 32) or in four groups, each group contained 8 animals. Home cage behavioural patterns were recorded weekly using ethogram-based instantaneous sampling for 5 consecutive weeks. Regardless of strain, single housed (SH) mice displayed higher levels of grooming and bedding directed-behaviours and were more frequently seen in-the-crawl ball, and had lower levels of feeding behaviour compared to their group housed (GH) conspecifics. There were significant strain differences in anxiety-related behaviours with the DBA/2 strain demonstrating higher levels of sleep, feeding and grooming behaviour and frequent presence in-the-crawl ball, and lower levels of exploration, locomotion and bedding-directed behaviour compared to the C57BL/6 strain. The results therefore suggest that different housing systems influence home cage behaviours of laboratory mice with the mice of the DBA/2 strain appearing more anxious. These findings may also have great implications for researchers to decide the most appropriate phenotype to use in measuring neural response–relevant behaviours in novel animal/human models