•FA and ZS utilize synergistically through ambient temperature geopolymerization.•Low reactivity of fly ash at ambient condition is overcome by addition of ZS.•Slag addition has modified the ...reactivity and more C-(A)-S-H gel is formed.•Compact microstructure with well bridged particles is observed in ZS rich blends.•Paving blocks confirm IS 15658 specification and meet US-EPA 1311 standard.
The potential for practical application of fly ash, zinc slag and their blends for geopolymer synthesis at ambient temperature have been investigated in this paper. Fly ash is an alumino-silicate byproduct suitable for geopolymer reaction, but its low reactivity at ambient condition is the restriction of its bulk utilization. Above limitation can be overcome by blending with zinc slag (ZS). Additionally, ZS contains heavy and toxic metals (Pb, Zn, Cr, Cd, As), which can be stabilize in Al-Si based geopolymer network structure. Isothermal conduction calorimetry (ICC) is used to monitor the geopolymer reaction with time. Slag rich specimens are characterized with higher rate of reaction with augmented peak. The mineralogy and microstructure of the geopolymers have been examined through X-ray diffraction and scanning electron microscope. The detected chief reaction product is N-(C)-A-S-H and C-(N)-A-S-H11(where, N=Na2O, C=CaO, A=Al2O3, S=SiO2 and H=H2O) type hydrated gel. Continual improvement of compressive strength of the geopolymers with increasing slag content is explained with higher degree of reaction, formation of more reaction products and development of compact microstructure. According to toxicity characteristic leaching procedure (TCLP), toxic metals leaching is within permissible limit. Paver blocks using 40−80 wt% ZS has been developed, which meets IS 15,658: 2006 standard and comply with US-EPA specification.
A series of arylidene-2-(4-(4-methoxy/bromophenyl) thiazol-2-yl) hydrazines (4a-z) and 1-(4-(4-methoxy/bromophenyl) thiazol-2-yl)-2-cyclohexylidene/cyclopentylidene hydrazines (5a-b/6a-b) were ...synthesized, characterized and screened for their antimicrobial activities. The structures of synthesized compounds were established by spectroscopic (FT-IR, (1)H NMR, (13)C NMR, Mass) and elemental analyses. Both the anti-bacterial and anti-fungal activities with MIC values of compounds were evaluated. The results of anti-bacterial screening reveal that among all the compounds screened eight compounds showed moderate to good anti-bacterial activity while ten of the newly synthesized compounds displayed good to excellent anti-fungal activity. Among the tested compounds, the most effective compounds with MIC value in the range of 6.25-25 microg/ml are 4a, 4n, 4z, 5a, 5b, 6a and 6b against three fungal strains viz. Candida albicans, Cryptococcus neoformans and Aspergillus flavus.
Smarter and minimization of devices are consistently substantial to shape the energy landscape. Significant amounts of endeavours have come forward as promising steps to surmount this formidable ...challenge. It is undeniable that material scientists were contemplating smarter material beyond purely inorganic or organic materials. To our delight, metal‐organic frameworks (MOFs), an inorganic‐organic hybrid scaffold with unprecedented tunability and smart functionalities, have recently started their journey as an alternative. In this review, we focus on such propitious potential of MOFs that was untapped over a long time. We cover the synthetic strategies and (or) post‐synthetic modifications towards the formation of conductive MOFs and their underlying concepts of charge transfer with structural aspects. We addressed theoretical calculations with the experimental outcomes and spectroelectrochemistry, which will trigger vigorous impetus about intrinsic electronic behaviour of the conductive frameworks. Finally, we discussed electrocatalysts and energy storage devices stemming from conductive MOFs to meet energy demand in the near future.
Ever increasing energy demand warrant smarter and minimized electronic devices which insist advanced materials. This review is to delineate the journey of metal‐organic frameworks (MOFs) from their dawn to commercialization for smarter world, blended with structure‐property relationships and theoretical investigation.
Isothermal conduction calorimetry has been used to study the reaction kinetics of early geopolymerization of fly ash. Fly ash particles were subjected to react with NaOH solution in 2:1 ratio at ...isothermal temperatures of 34, 39, 45, 52, and 60 °C. The reaction kinetic parameters such as activation energy, rate of reaction, and pre-exponential function were calculated using the rate of heat evolution data. It is observed that the geopolymerization reaction followed a nucleation and growth mechanism. The activation energy obtained from an Arrhenius plot was around ~100 kJ mol
−1
.
Continuous cooling transformation (CCT) diagrams were determined for weld simulated coarse grained heat affected zone (CGHAZ) of Nb-microalloyed and HY 85 steels using a Gleeble®3800 ...thermo-mechanical simulator. Samples were heated to a peak temperature of 1573K (1300°C) and cooled at different cooling rates from 0.5K/s to 120K/s. Microstructures, hardness, and impact toughness at 223K were determined corresponding to simulated samples of weld CGHAZ thermal cycles. Transformation temperatures AC3, AC1, Bs, Bf, Ms, and Mf were also determined using dilatometric analysis. At slow cooling rates pro-eutectoid ferrite and pearlite were observed in Nb-microalloyed steel and a mixture of bainitic ferrite and granular bainite was observed in HY 85 steel but no pro-eutectoid ferrite was observed. At moderate cooling rates, only bainite was observed in both the steels. At high cooling rates, lath martensite was observed for both the steels. A strong dependence of prior austenite grain size on mechanical properties has been found. A prior austenite grain size of approximately 30μm (80K/s) has shown impact toughness more than 100J and 198J for Nb-microalloyed steel and HY85 steel samples respectively. Based on microstructures, hardness, impact toughness, and transformation temperatures, CCT diagrams for the weld CGHAZ region were determined.
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•Based on microstructures, hardness, impact toughness, and dilatometric studies using thermo-mechanical simulator, CCT diagrams for Nb-microalloyed and HY 85 steels have been constructed for weld CGHAZ region.•In HY 85 steel, no proeutecoid ferrite and pearlite have been observed at slower cooling rates and for higher cooling rates bainite, bainite & martensite, and martensite have been observed.•For Nb-microalloyed and HY 85 steels, a cooling rate of approximately 35K/s and 70K/s respectively will ensure a hardness value of 350VHN in the weld CGHAZ region which is considered safe from the point of view of cold cracking.•HY 85 steel shows higher impact toughness as compared to Nb-microalloyed steel at all test temperatures. HY 85 steel shows impact toughness greater than 78J at cryogenic temperature (223K) for cooling rate between 40K/s and 70K/s.•Prior austenite grain size (PAGS) values have shown a strong influence on impact toughness and hardness. The higher the PAGS the lower the impact toughness and hardness value are.
This work focuses on gainful utilization of low reactive fly ash at ambient temperature into alkali-activated binder with the addition of another industrial waste silico-manganese (SiMn) slag. ...Granulated SiMn slag (GSS) percentage was gradually increased into fly ash-based reference batch. The influence of slag on reactivity of the blends was monitored by isothermal conduction calorimetry. Reactivity was improved with increasing slag content. The structural reorganizations of the resultant binder were detected by peak shifting in Fourier transform infrared spectroscopy study. The positional change of the hump in X-ray diffraction analysis was due to structural rearrangement of the binder. The calcium-rich hydrated product formation was increased with slag inclusion. The fly ash-derived geopolymer gel (N–A–S–H) was coexisted with slag activated gel (C–S–H/C–A–S–H), (where N = Na
2
O, A = Al
2
O
3
, C = CaO, S = SiO
2
, and H = H
2
O) in the blend matrix. EDX analysis confirmed the variation in Si/Al, Ca/Si, and Na/Al ratios of the binder with the alteration of reaction products. The development of better compressive strength in slag-rich binder attributed with the formation of Ca-rich gel phases.
Physical processes that occur during hot compression tests performed on AISI1010 steel in the temperature range of 750°C–1050°C and strain rates range of 0.01–20s−1 are discussed using ...microstructural observations and are related to the stress-strain response. The apparent activation energy is 177kJ/mol and the stress exponent is 3.5, which suggest that the deformation is controlled by dislocation glide and climb. Temperature rise due to deformation is considered in characterizing the flow softening behavior. Processing maps created using different models are discussed together with change in the Zener-Hollomon parameter (Z) in the domain of strain rates and temperatures. Z is related to the power dissipation efficiency, flow stress, and microstructural evolution. Lower values of Z promoted the restoration processes. Dynamic recrystallization is the primary restoration mechanism between 750°C and 875°C and in the 0.01–0.1s−1 range, where highest power dissipation efficiency is observed.
The city of Kolkata is one of the most urbanized and densely populated regions in the world and a major industrial and commercial hub of the eastern and northeastern region of India. In order to ...classify the seismic risk zones of Kolkata we used seismic hazard exposures on the vulnerability components, namely land use/land cover, population density, building typology, age and height. We microzoned seismic hazard of the city by integrating seismological, geological and geotechnical themes in GIS, which in turn are integrated with the vulnerability components in a logic-tree framework for the estimation of both the socioeconomic and structural risk of the city. In both the risk maps, three broad zones have been demarcated as "severe", "high" and "moderate". There had also been a risk-free zone in the city that is termed as "low". The damage distribution in the city due to the 1934 Bihar-Nepal earthquake of Mw = 8.1 matches satisfactorily well with the demarcated risk regime. The design horizontal seismic coefficients for the city have been worked out for all the fundamental periods that indicate suitability for "A", "B" and "C" type of structures. The cumulative damage probabilities in terms of "none", "slight", "moderate", "extensive" and "complete" have also been assessed for the predominantly four model building types viz. RM2L, RM2M, URML and URMM for each seismic structural risk zone in the city. Both the seismic hazard and risk maps are expected to play vital roles in the earthquake-inflicted disaster mitigation and management of the city of Kolkata.
Large true strain (up to ~4.7) through hybrid severe plastic deformation (HSPD) technique was imparted to Mg–4Zn–4Gd alloy, to study its influence on microstructural evolution, fracture toughness and ...tensile properties in the present work. The tensile and fracture toughness of processed Mg alloy were compared with solutionized bulk Mg alloy. The tensile properties are found to be superior in multiaxially forged followed by repetitive rolled specimen at 723 K compared to ST sample. The key strengthening mechanisms such as microstructural bimodality, coherency of the twin boundaries, and precipitation are characterized in detail, to elucidate the enhancement in hardness (~61%), tensile (~62%), yield (~42%) and elastic-plastic fracture toughness (~40%) properties. These improvements are observed in the optimised thermo-mechanically processed condition “6 pass hot forged followed by 75% repetitive hot rolled (6PF-75R) specimen”. However, high dislocation density observed in 6PF-75R specimen leads to lower the ductility compared to other HSPDed conditions but still found higher than that of the solutionized specimens. The fracture phenomena were also explored through post-deformation processed samples through scanning electron microscopy based fractograph to understand the response of different processed specimens using tension and fracture tests. Various microstructural features such as microshear bands, nano-twinning, slip clusters and especially the effect of continuous dynamic recrystallization upon varying true strain are examined by using high-resolution transmission electron microscopy (HR-TEM) and low angle annular dark field scanning transmission electron microscopy (LAADF-STEM) techniques. Correlation of these features with tensile and fracture behaviour are made with the support of light microscopy and X-ray diffraction techniques.
Magnetoelectric coupling, magnetoimpedance and dielectric properties are investigated for spin–charge dependent magnetoelectric LaFeO3-poly(vinylidene fluoride) hybrid nanocomposites. The X-ray ...diffraction pattern indicates that both LaFeO3 and poly(vinylidene fluoride) phases coexist in the nanocomposites. The magnetoelectric coupling measurement confirms the multiferroic in nature of the nanocomposites. Magnetoelectric and magnetocapacitance (∼42%) effects are ascribing the improvement of space charge polarization of nanocomposites. The light of classical electrodynamics causes the room temperature magnetoimpedance effect (∼94%). Temperature dependent ac conductivity suggests the observation of negative temperature coefficient resistance behavior that also obeys the single Jonscher's power law. The conduction mechanism of the system is controlled through small and large polaronic hopping. Activation energy of those polymer based hybrid nanocomposites is estimated using Arrhenius relation. The magnetoelectric coupling of the nanocomposites is enhanced with an increase in poly(vinylidene fluoride) content. The inorganic-organic based nanocomposites could be a favorable candidate for improvement of magnetoelectric devices, smart energy storage and energy harvesting device applications.
•Magnetoelectric coupling of polymer hybrid nanocomposites has been investigated.•Magnetoelectric and magnetocapacitance effects attribute space charge polarization.•Light of classical electrodynamics causes room temperature magnetoimpedance effect.•AC conductivity obeys the Jonscher's single power law.•The activation energy has been estimated using Arrhenius relation.
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