Background
Little is known about the estrogen exposure measurement and mutual effect of age at menarche and age at menopause in the risk of cardiovascular disease (CVD) events.
Objectives
To evaluate ...estrogen exposure measurement and describe mutual effect of age at menarche and age at menopause in the risk of CVD events.
Search strategy
Systematic review of literature in PubMed, Embase and Web of Science for studies published up to 28 June 2020.
Selection criteria
Observational studies related to estrogen exposure measurement, including mutual effect of age at menarche and age at menopause and risk of CVD events.
Data collection and analysis
Synthesis of evidence was conducted by reviewing individual estimates, followed by meta‐analysis. The study received no external funding.
Main results
A total of 75 studies were included in synthesis of evidence, of which 17 studies were included in meta‐analysis. Reproductive lifespan (age at menopause – age at menarche), endogenous estrogen exposure and total estrogen exposure were used for estrogen exposure measurement. Reproductive lifespan was by far the most commonly used method for estrogen exposure measurement. A shorter reproductive lifespan was associated with a higher risk of CVD events; the pooled relative risk (95% CI) was 1.31 (1.25–1.36) for stroke events. Robust epidemiological studies with measurement of estrogen exposure and associated health risk would strengthen the evidence.
Conclusions
Reproductive lifespan was the most commonly used method for estrogen exposure measurement in epidemiological studies. A shorter reproductive lifespan was associated with a higher risk of CVD events, particularly stroke.
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A systematic review and meta‐analysis found that women with a shorter reproductive lifespan have a higher risk of stroke events.
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A systematic review and meta‐analysis found that women with a shorter reproductive lifespan have a higher risk of stroke events.
Cold rolled AZ31 magnesium alloy sheet was subjected to friction stir processing to generate four average grain sizes ranging from 0.8 to 9.6μm. The processed material exhibited a strong basal fiber ...texture with the c-axis tilted about 35–55° towards the processing direction. The grain size and texture dependence of mechanical behavior were evaluated by using tensile testing along two orthogonal directions. Remarkably high ductility of ∼65% was achieved in relatively coarse grained material that fractured without developing necking when tested in the processing direction. The ductility decreased significantly to ∼10% for ultrafine grained material as the tensile yield strength increased from ∼53MPa to ∼180MPa. Grain size had limited influence on ductility of processed material tested in transverse direction, but reduced the uniform elongation to ∼2% for ultrafine grained material which exhibited ∼320MPa yield strength. Accompanying the significant anisotropy in tensile strength in two directions, the deformation of processed AZ31 in the processing direction was mainly accommodated through basal slip and extension twinning (except for ultrafine grained material); however, the deformation of material in transverse direction was dominated by non-basal slip. Influences of grain size and texture on mechanical behavior were studied in terms of work-hardening and deformation mechanisms.
Nanocrystalline metals, with a mean grain size of less than 100 nanometres, have greater room-temperature strength than their coarse-grained equivalents, in part owing to a large reduction in grain ...size. However, this high strength generally comes with substantial losses in other mechanical properties, such as creep resistance, which limits their practical utility; for example, creep rates in nanocrystalline copper are about four orders of magnitude higher than those in typical coarse-grained copper. The degradation of creep resistance in nanocrystalline materials is in part due to an increase in the volume fraction of grain boundaries, which lack long-range crystalline order and lead to processes such as diffusional creep, sliding and rotation. Here we show that nanocrystalline copper-tantalum alloys possess an unprecedented combination of properties: high strength combined with extremely high-temperature creep resistance, while maintaining mechanical and thermal stability. Precursory work on this family of immiscible alloys has previously highlighted their thermo-mechanical stability and strength, which has motivated their study under more extreme conditions, such as creep. We find a steady-state creep rate of less than 10(-6) per second-six to eight orders of magnitude lower than most nanocrystalline metals-at various temperatures between 0.5 and 0.64 times the melting temperature of the matrix (1,356 kelvin) under an applied stress ranging from 0.85 per cent to 1.2 per cent of the shear modulus. The unusual combination of properties in our nanocrystalline alloy is achieved via a processing route that creates distinct nanoclusters of atoms that pin grain boundaries within the alloy. This pinning improves the kinetic stability of the grains by increasing the energy barrier for grain-boundary sliding and rotation and by inhibiting grain coarsening, under extremely long-term creep conditions. Our processing approach should enable the development of microstructurally stable structural alloys with high strength and creep resistance for various high-temperature applications, including in the aerospace, naval, civilian infrastructure and energy sectors.
Friction stir welding (FSW) is a relatively new solid-state joining process. This joining technique is energy efficient, environment friendly, and versatile. In particular, it can be used to join ...high-strength aerospace aluminum alloys and other metallic alloys that are hard to weld by conventional fusion welding. FSW is considered to be the most significant development in metal joining in a decade. Recently, friction stir processing (FSP) was developed for microstructural modification of metallic materials. In this review article, the current state of understanding and development of the FSW and FSP are addressed. Particular emphasis has been given to: (a) mechanisms responsible for the formation of welds and microstructural refinement, and (b) effects of FSW/FSP parameters on resultant microstructure and final mechanical properties. While the bulk of the information is related to aluminum alloys, important results are now available for other metals and alloys. At this stage, the technology diffusion has significantly outpaced the fundamental understanding of microstructural evolution and microstructure–property relationships.
The negative impact of heat stress on cattle growth, development, reproduction and production has been quite alarming across the world. Climate change elevates earth surface temperature which ...exacerbates the wrath of heat stress on cattle. Moreover, cattle in tropical and sub-tropical countries are most commonly affected by the menace of heat stress which severely wane their production and productivity. In general, cattle exhibit various thermoregulatory responses such as behavioural, physiological, neuro-endocrine and molecular responses to counteract the terrible effects of heat stress. Amongst the aforementioned thermoregulatory responses, behavioural, physiological and neuro-endocrine responses are regarded as most conventional and expeditious responses shown by cattle against heat stress. Furthermore, molecular responses serve as the major adaptive response to attenuate the harmful effects of heat stress. Therefore, present review highlights the significance of behavioural, physiological, neuro-endocrine and molecular responses which act synergistically to combat the deleterious effects of heat stress thereby confer thermo-tolerance in cattle.
The present analysis describes the effect of dissipative heat energy transfer in Ethylene–Glycol (EG) based on conducting nanofluid over a heated semi-infinite vertical plate past through a porous ...medium. Uniform magnetic field, heat source/sink, and the effect of particle concentration also have been discussed by incorporating in the energy and solutal transfer equations, respectively. In addition to that, the thermal properties of the nanofluid are affected by the thermal slip boundary condition since; the temperature slip is favorable for the reduction in the heat transfer. Assuming self-similar transformations, the governing PDEs are transformed into non-linear coupled ODEs. These transformed equations are solved by using semi-analytical techniques such as Adomian Decomposition Method (ADM). The characteristics of different parameters on the flow phenomena are obtained and presented via graphs. The numerical values of the thermophysical properties of both the nanoparticles and the base fluid are shown in the table. Validation of the present work is obtained by comparing our result with the earlier established result and it is found that both the results are coinciding with each other. However, the main quantified results are the following: due to heavy density of the Cu nanoparticles, increasing volume fraction in ethylene–glycol base fluid resists the fluid motion and the inclusion of dissipative heat energy is favorable to enhance the nanofluid temperature.
High heat and humidity stress have been a perpetual perilous for the buffalo's production and productivity in tropics and subtropics including India. Productive potential of livestock's species ...including buffaloes is maximum with in thermo-neutral zone (TNZ) and if ambient temperature exceeds TNZ and upper critical temperature expose livestock's to heat stress conditions. For decades, heat stress has been the prime factor to plummet buffalo's growth, development, reproduction and production in tropics and subtropics including India. In general, buffaloes are homeotherms and known as temperature regulators as they resist the variations in ambient temperatures. Generally, buffaloes like other livestock's display amalgamation of thermoregulatory responses to withstand the changes occurred in their micro and macro environment. These thermoregulatory responses are behavioural, physiological, neuro-endocrine and molecular responses acting synergistically to counteract the deleterious effects of heat stress. Amidst all responses, molecular responses play major role to confer thermo-tolerance through expression of highly conserved family of proteins known as heat shock proteins (HSPs). Despite of these thermoregulatory responses, heat stress prodigiously muddles buffalo's production and productivity. The present review highlights the thermoregulatory responses manifested by riverine buffaloes against heat stress.
•Behavioural, physiological and neuro-endocrine responses are considered as the acute responses exhibited by buffaloes against heat stress.•Wallowing is considered as the major behavioural response in buffaloes against heat stress.•Rectal temperature is considered as the most reliable indicator while respiration rate is regarded as the most sensitive indicator to quantify the intensity of heat stress in buffaloes.•Cortisol is the principal stress alleviating hormone in buffaloes.•Molecular responses exhibited via HSPs play a major role in thermo-tolerance and differential expression of miRNAs regulates heat stress responses in buffaloes.
In this work, multi-pass friction stir processing (FSP) was successfully applied to AA6061 to reinforce SiC nanoparticles producing defect-free processes. It can be inferred that Nano SiC particles ...were fragmented totally and uniformly distributed in sixth pass FSP. Agglomeration of SiC particles decreases with increases in the number of FSP pass. In the first pass, the SiC powder with lower formability than the base metal was concentrated inside the groove, so their flow was difficult, and most of them remained at the center of the SZ. The amount of SiC in the surface composite was further decimated after the second pass FSP cycle. At the same time, a progressive and substantial fragmentation of SiC particles ensues after the fourth and sixth passes, respectively, due to improving material mixing and dispersion. The tensile strength of AA6061 exhibited 275.7 MPa, and a percentage strain of 10.9. After implementing multi-pass FSP with nanoparticles of SiC on the AA6061, the tensile properties were enhanced simultaneously as the FSP pass increases. The tensile strength of one pass, two passes, four passes, and six passes was observed as 291.8, 307.5, 330.5, and 348 MPa, respectively, caused by strain-free fine grains during dynamic recrystallization mechanism. In contrast, Vickers's hardness value along the centerline (stir zone) was observed as 101, 119, 125, and 134 HV with 1, 2, 4, and 6 FSP pass, respectively.
•A Mg alloy build has been fabricated using friction stir additive manufacturing.•Maximum hardness of 135HV was attained and is similar to Al 2XXX alloys.•Good combination of strength (400MPa) and ...ductility (17%) was obtained.•Origin of high strength and ductility are correlated with the microstructure.
Structural performance is a key challenge pertinent to additive manufacturing. A majority of the current techniques employed for metallic materials involve liquid–solid transformation and their performance is limited by solidification microstructures. Depending on the type of metallic alloy, this can be a serious impediment to structural properties. In this regard, solid-state additive manufacturing techniques have lagged behind. This study is focused on friction stir additive manufacturing (FSAM) as a potential technique to attain structurally efficient magnesium alloys. In this study, a multilayered stack of an Mg based WE43 alloy was built using FSAM at two different welding parameters. Formation of defects is sensitive to the heat input. In addition, dynamic recrystallization led to finer grain size (2–3μm). Such fine grain size coupled with desirable precipitate characteristics culminated in superior mechanical properties. Maximum hardness of 115HV was obtained in as-fabricated state and increased to 135HV after aging. These levels are similar to Al 2XXX alloys. In fact, in terms of strength, it translates to 400MPa and 17% ductility and is significantly higher than the base material subjected to aging. Mechanical properties have been correlated with detailed microstructural observations. Texture is discussed for a higher heat input sample using orientation imaging microscopy.
► Ultrafine grain Mg–Y–RE showed one order lower magnitude of corrosion rate as compared to coarse grain. ► Higher linear polarization resistance was observed for ultrafine grain Mg–Y–RE. ► Cyclic ...polarization study showed repassivation behavior for ultrafine grained Mg–Y–RE. ► A power–law relationship between grain size and corrosion rate is proposed.
A range of grain size from 70μm to 0.7μm was studied for corrosion resistance of Mg–Y–RE magnesium alloy using electrochemical and constant immersion testing in 3.5wt.% NaCl solution. The linear polarization resistance (Rp) showed a clear trend of increasing Rp value with grain refinement. The ultrafine grained sample showed the most positive pitting potential as compared to coarse grained samples. One order of magnitude decrease in corrosion rate was observed between coarsest and ultrafine grained microstructure.
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