Bio: Vaibhav Rathi is an academic researcher from Development Alternatives Incorporated. The author has contributed to research in topics: Medicine & Cementitious. The author has an hindex of 2, co-authored 2 publications receiving 39 citations.
TL;DR: In this paper, the authors proposed a framework for sustainability assessment, in terms of the CO2 emissions and energy demand, that can be adopted in cases where suitable databases are not readily available.
Abstract: The consumption of cement in India and other emerging economies is expected to increase because of the continuing push towards development of housing and infrastructure. The increasing production of cement and utilization of concrete are bound to have a major impact on sustainability. The present work proposes a framework for sustainability assessment, in terms of the CO2 emissions and energy demand, that can be adopted in cases where suitable databases are not readily available. Case studies for cement manufacture have been considered in South India, with different system boundaries such as ground-to-gate, gate-to-gate and CSI. The assessment made using data from the plant and other sources highlights the benefits of using supplementary cementitious materials (SCMs) in terms of reducing the impact of cement and concrete. More importantly, limestone calcined clay cement shows considerable promise in terms of reduction in CO2 emissions and energy demand in both cement and concrete, with more improvement in higher grade concrete.
01 Jan 2016
TL;DR: Various factors that have been shown to contribute to renal injury in many experimental models of nephropathy are focused on.
Abstract: Nephropathy has become the most common reason for end-stage renal disease worldwide. The progression of end-stage renal disease occurs caused by decreased glomerular filtration rate, damage to capillaries in renal glomeruli or a higher risk of cardiovascular morbidity and mortality in diabetic patients. The involvement of mechanism in the development of nephropathy via generation of AGEs, the elevation of growth factors, altered hemodynamic and metabolic factors, inflammatory mediators, oxidative stress and dyslipidaemia. The prevalence of chronic kidney disease in India will rise from 3.7 million in 1990 to 7.63 million in 2020 becoming the main cause of mortality and morbidity. The pathogenesis of nephropathy mediates by various molecules that cause alterations in the structure and function of the kidney like growth factors, endothelins, transforming growth factor (TGF-β), and Angiotensin-converting enzymes (ACE), fibronectin and pro-inflammatory cytokines, mast cells and dyslipidemia. Growth factors like VEGF, IGFs, PDGF, EGFR and TGF-β contribute to excessive extracellular matrix accumulation, together with thickening of the glomerular and tubular basement membranes and an increase in the mesangial matrix, leading to glomerulosclerosis and tubulointerstitial fibrosis. Oxidative stress and inflammation factors like TNF-α, IL-1 and IL-6 are hypothesized to play a role in the development of pathological changes in nephropathy like renal hyperfiltration and hypertrophy, thickening of the glomerular basement membrane (GBM), glomerular lesion and tubulointerstitial fibrosis. Dyslipidemia is involved in the progression of nephropathy by impaired action of lipoprotein lipase, lecithin-cholesterol acyltransferase (LCAT) and cholesteryl ester transferase protein (CETP) resulting in the increased level of LDL-C, Triglyceride level and decrease HDL-C that enhance macrophage infiltration, excessive extracellular matrix production and accelerate inflammation with the development of proteinuria. Interruption in the RAS, oxidative stress and dyslipidemia have yielded much better results in terms of reno-protection and progression of nephropathy. In this review, we would focus on various factors that have been shown to contribute to renal injury in many experimental models of nephropathy.
TL;DR: In this paper , the authors used georeferenced data on more than 2 million births matched to satellite-derived burned area exposure to estimate the burden of biomass fires on infant mortality, finding that each additional square kilometer of burning is associated with nearly 2% higher infant mortality in nearby downwind locations.
Abstract: Global outdoor biomass burning is a major contributor to air pollution, especially in low- and middle-income countries. Recent years have witnessed substantial changes in the extent of biomass burning, including large declines in Africa. However, direct evidence of the contribution of biomass burning to global health outcomes remains limited. Here, we use georeferenced data on more than 2 million births matched to satellite-derived burned area exposure to estimate the burden of biomass fires on infant mortality. We find that each additional square kilometer of burning is associated with nearly 2% higher infant mortality in nearby downwind locations. The share of infant deaths attributable to biomass fires has increased over time due to the rapid decline in other important causes of infant death. Applying our model estimates across harmonized district-level data covering 98% of global infant deaths, we find that exposure to outdoor biomass burning was associated with nearly 130,000 additional infant deaths per year globally over our 2004 to 2018 study period. Despite the observed decline in biomass burning in Africa, nearly 75% of global infant deaths due to burning still occur in Africa. While fully eliminating biomass burning is unlikely, we estimate that even achievable reductions-equivalent to the lowest observed annual burning in each location during our study period-could have avoided more than 70,000 infant deaths per year globally since 2004.
TL;DR: The therapeutic potential of hesperidin, a traditionally used herbal medicine with an exceptional safety profile, is discussed and a novel anti-COVID-19 lead is proposed based on its multifaceted bioactivities.
Abstract: COVID-19, aka Coronavirus Disease 2019, triggered by new severe acute respiratory syndrome coronavirus-2 or SARS-CoV-2, is now a public health emergency due to its rapid spread, high transmission efficiency, and severe viral pandemic that is significantly increasing the number of patients and associated deaths. At present, no specific treatment is available that can this highly contagious virus. The unavailability of effective and specific treatments and the severity of this epidemic situation potentiate medicinal chemists' in supporting new prophylactic or therapeutic interventions against COVID-19. This study discusses the therapeutic potential of hesperidin, a traditionally used herbal medicine with an exceptional safety profile. Recent studies on hesperidin advocate its promising potential in the prevention and management of COVID 19. This paper also discussess the recent clinical studies based on the previously documented antiviral activity of hesperidin. Herein, we propose the detailed preclinical and clinical manifestations of hesperidin based on its multifaceted bioactivities to develop a novel anti-COVID-19 lead.
TL;DR: In this article, the authors presented data on the chloride diffusion coefficient (Dcl), ageing coefficient (m) and chloride threshold (Clth) related to seven concrete mixes (four M35 and three M50) with OPC, OPC+PFA (pulverised fuel ash) and limestone-calcined clay cement (LC3).
Abstract: This paper presents data on the chloride diffusion coefficient (Dcl), ageing coefficient (m) and chloride threshold (Clth) related to seven concrete mixes (four M35 and three M50) with OPC, OPC + PFA (pulverised fuel ash) and limestone-calcined clay cement (LC3). Using these, the service lives of a typical bridge pier and girder with the PFA and LC3 concrete were found to be much higher than those with OPC concrete of similar strength. From life-cycle assessment, the CO2 footprint of PFA and LC3 concrete were found to be significantly lower than those of OPC concrete of similar strength. Further, the CO2 emissions per unit of concrete per year of estimated service life, as a combined indicator of service life and carbon footprint, are similar for concrete with PFA and LC3, which are much lower than that with OPC.
TL;DR: A review of the literature available on the subject of the recently developed limestone calcined clay cement (LC3) can be found in this article, where an introduction to the background leading to the development of LC3 is discussed.
Abstract: This article reviews the rapidly developing state-of-the-art literature available on the subject of the recently developed limestone calcined clay cement (LC3). An introduction to the background leading to the development of LC3 is first discussed. The chemistry of LC3 hydration and its production are detailed. The influence of the properties of the raw materials and production conditions are discussed. The mixture design of concrete using LC3 and the mechanical and durability properties of LC3 cement and concrete are then compared with other cements. At the end the economic and environmental aspects of the production and use of LC3 are discussed. The paper ends with suggestions on subjects on which further research is required.
TL;DR: In this article, a review summarises literature to examine the transition from portland limestone cement system to composite ternary binder systems involving limestone and the interaction of fine limestone is classified and elaborated under two broad umbrellas: physical and chemical interactions.
Abstract: The review summarises literature to examine the transition from portland limestone cement system to composite ternary binder systems involving limestone. Interest in limestone addition as an ideal component in multicomponent binder systems has surged as evident from the large volume of literature published in the recent past. A ternary blended system, with co-substitution of limestone, has the potential to complement the reaction of the supplementary cementitious materials (SCMs). The direct addition of limestone powder helps to attain higher substitution levels of portland cement clinker, improve early age properties, and supplement SCM's reactivity. However, the dilution of hydrates could hamper the long-term benefits. In this review, the interaction of fine limestone is classified and elaborated under two broad umbrellas: physical and chemical interactions. The physical interactions can manifest in three ways, namely, filler action, shearing action and improved packing, which alters reaction rate and extent at early ages. The chemical interactions also modify the reaction kinetics and phase assemblage due to nucleation of C-S-H on calcite surfaces, preservation of the ettringite phase and formation of carboaluminates. Two different forms of carboaluminate hydrates — hemicarboaluminate and mono-carboaluminate can be present in the hydrate matrix depending on the balance between carbonate ions and aluminates in the pore solution. Several factors such as replacement level, particle size, choice of SCM, its reactivity and reactive aluminates content, sulphate levels, curing temperature, and duration of curing can control the carboaluminate formation, reaction degree of SCMs and chemical interaction from limestone additions. A combination of physical and chemical effects makes fine limestone a potential material for co-substitution with aluminosilicate based SCMs, mainly fly ash, slag, and calcined clay. In this review, the factors affecting limestone-SCM composites are summarised based on a detailed literature survey. The effects of SCM-limestone cement composites on hydration kinetics, reaction chemistry, the reactivity of SCMs, the stability of hydrated phases, and contribution to the physical structure development and macroscopic properties by evaluating hydration and mechanical properties are discussed. The importance of AFm (Al2O3–Fe2O3-mono) phases in various deterioration mechanisms in concrete and their influence on performance characteristics in different exposure environment is critically appraised.
TL;DR: In this article, a prospective approach to conduct sustainability assessment based on the life cycle of 3D printed structures is presented, which also highlights the importance of considering the functional requirements of the mixes used for 3D printing.
Abstract: This paper explores the sustainability aspects of binders used in concrete 3D concrete printing. Firstly, a prospective approach to conduct sustainability-assessment based on the life cycle of 3D printed structures is presented, which also highlights the importance of considering the functional requirements of the mixes used for 3D printing. The potential of the material production phase is emphasized to enhance the sustainability potential of 3DCP by reducing the embodied impacts. The literature on the different binder systems used for producing 3D printable mixtures is reviewed. This review includes binders based on portland cement and supplementary cementing materials (SCMs) such as fly ash, silica-fume and slag. Also, alternative binders such as geopolymer, calcium sulfo-aluminate cement (CSA), limestone calcined clay cement (LC3) and reactive magnesium oxide systems are explored. Finally, sustainability assessment by quantifying the environmental impacts in terms of energy consumed and CO2 emissions of mixtures is illustrated with different binder systems. This paper underlines the effect of using SCMs and alternative binder systems for improving the sustainability of 3D printed structures.
TL;DR: In this article, the role of microstructure in terms of the chemical composition of C-A-S-H and its physical states in the different systems is identified as the critical factor governing the development of micro-structure.
Abstract: This paper discusses the role of physical structure alterations on three binder types: plain portland cement, fly ash-based binder and calcined clay-limestone binder. The kinetics of physical structure development and the relevance in transport properties were distinguished using an interlinked parameter in concrete and paste. A systematic experimental investigation was carried out on a range of critical parameters such as strength development, resistivity development, transport characteristics and the time-dependent change in transport parameter. The role of microstructure in terms of the chemical composition of C-A-S-H and its physical states in the different systems is identified as the critical factor governing the development of microstructure. Chloride resistance was assessed by chloride migration experiments for a period of 4 years. The durability behaviours of the concrete with various binder were generalised using pore network parameters such as formation factor and tortuosity. A sensitivity analysis was used to dissect the contribution of the pore solution dilution and pore connectivity to the change in the pore network parameter. Based on the rise in macroscopic physical characteristics (i.e., formation factor here), a two-fold structure development mechanism to conceptualise microstructural evolution in cement composites is presented. Initially, capillary pore space reduces to a critical size range (i.e., 10–30 nm), which is followed by the densification of the physical state of the microstructure. At the point of densification, the pores become largely disconnected which leads to a dramatic increase in the formation factor. The binding matrix in calcined clay concretes reaches the critical pore size at an early age which leads to early densification of capillary pore space region in comparison to fly ash concretes.