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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.

Seismic microzonation is a process of estimating site-specific effects due to an earthquake on urban centers for its disaster mitigation and management. The state of West Bengal, located in the western foreland of the Assam–Arakan Orogenic Belt, the Himalayan foothills and Surma Valley, has been struck by several devastating earthquakes in the past, indicating the need for a seismotectonic review of the province, especially in light of probable seismic threat to its capital city of Kolkata, which is a major industrial and commercial hub in the eastern and northeastern region of India. A synoptic probabilistic seismic hazard model of Kolkata is initially generated at engineering bedrock (Vs30 ~ 760 m s−1) considering 33 polygonal seismogenic sources at two hypocentral depth ranges, 0–25 and 25–70 km; 158 tectonic sources; appropriate seismicity modeling; 14 ground motion prediction equations for three seismotectonic provinces, viz. the east-central Himalaya, the Bengal Basin and Northeast India selected through suitability testing; and appropriate weighting in a logic tree framework. Site classification of Kolkata performed following in-depth geophysical and geotechnical investigations places the city in D1, D2, D3 and E classes. Probabilistic seismic hazard assessment at a surface-consistent level – i.e., the local seismic hazard related to site amplification performed by propagating the bedrock ground motion with 10% probability of exceedance in 50 years through a 1-D sediment column using an equivalent linear analysis – predicts a peak ground acceleration (PGA) range from 0.176 to 0.253 g in the city. A deterministic liquefaction scenario in terms of spatial distribution of liquefaction potential index corresponding to surface PGA distribution places 50% of the city in the possible liquefiable zone. A multicriteria seismic hazard microzonation framework is proposed for judicious integration of multiple themes, namely PGA at the surface, liquefaction potential index, NEHRP soil site class, sediment class, geomorphology and ground water table in a fuzzy protocol in the geographical information system by adopting an analytical hierarchal process. The resulting high-resolution surface consistent hazard, liquefaction and microzonation maps are expected to play vital roles in earthquake-related disaster mitigation and management of the city of Kolkata.

Synthesis of cordierite (5SiO 2 ·2MgO·2Al 2 O 3 ) has attracted special attention from researchers for its special characteristics. Most common method of cordierite preparation is solid-state reaction using source of alumina, silica and magnesia, which requires temperature of 1350 °C or above. This study deals with the effect of mechanical activation on cordierite synthesis at lower temperature. Talc, kaolinite clay and alumina powder were taken as precursor materials and the batches were formulated on the basis of stoichometric cordierite formation. Particle size distribution (PSD) was measured to get the distribution pattern of milled powder. Pellets were prepared by compaction of dried milled powders and fired at 1200 °C temperature. X-ray diffraction (XRD) technique was used to characterize crystalline phases. Microstructural analysis was done under scanning electron microscope (SEM). It was observed that properties were improved with milling time. Dense and uniform microstructures were formed when samples were milled for 45 and 60 min.

The discharge of chromium-contaminated wastewater from industries such as ferrochrome plants and leather manufacturing poses a significant environmental challenge due to the toxic and carcinogenic properties of Chromium [Cr(VI)]. Nanoparticles have emerged as one of the most effective solutions for wastewater treatment due to their high surface area, enhanced reactivity, and ability to target specific contaminants. In recent years, their eco-friendly synthesis, scalability, and efficiency in removing heavy metals and other pollutants have made them vital in addressing environmental challenges, particularly in industrial wastewater management. Their unique properties make them indispensable in modern wastewater treatment technologies. This study explores the application of biogenically synthesized titanium dioxide (TiO₂) for removal of Cr(VI) from synthetic wastewater. Lemon grass leaf extracts has been used as potential precursor in synthesis of TiO₂ nanoparticles from readily available micro size particles of TiO 2 powder. The process was further enhanced by ultrasonic assistance, which promoted the formation of uniformly dispersed nanoparticles with high surface area, improving their adsorption. Experimental techniques, such as X-ray Diffraction, have been utilized to confirm the biogenic synthesis of TiO 2 nanoparticles, demonstrating a size reduction from 10 μm to 35.79 nm. The nanoparticles demonstrated excellent Cr(VI) removal efficiency, achieving 84.55% reduction under optimal conditions. Among the various adsorption isotherm models, the Freundlich model proved to be the best fit, with an R² value exceeding 0.997. This method not only leverages sustainable synthesis processes but also offers potential scalability for industrial applications in waste water treatment.

A comparative study was carried out on the development of ultrafine-grained dual-phase (DP) (ferrite–martensite) structures in a low-carbon microalloyed steel processed using two thermomechanical processing routes, (i) intercritical deformation and (ii) warm-deformation and intercritical annealing. The samples were deformed using Gleeble3500 ® simulator, maintaining a constant total strain ( ε  = 1) and strain rate ( ε ˙  = 1/s). Evolution of microstructure and micro-texture was investigated by SEM, TEM, and EBSD. Ultrafine-grained DP structures could be formed by careful selection of deformation temperature, T def (for intercritical deformation) or annealing temperature, T anneal (for warm-deformation and annealing). Overall, the ferrite grain sizes ranged from 1.5 to 4.0  μ m, and the sizes and fractions of the uniformly distributed fine-martensitic islands ranged from 1.5 to 3.0  μ m and 15 to 45 pct, respectively. Dynamic strain-induced austenite-to-ferrite transformation followed by continuous (dynamic) recrystallization of the ferrite dictated the grain refinement during intercritical deformation, while, continuous (static) recrystallization by pronounced recovery dictated the grain refinement during the warm-deformation and the annealing. Regarding intercritical deformation, the samples cooled to T def indicated finer grain size compared with the samples heated to T def , which are explained in terms of the effects of strain partitioning on the ferrite and the heating during deformation. Alpha-fiber components dominated the texture in all the samples, and the fraction of high-angle boundaries (with >15 deg misorientation) increased with the increasing T def or T anneal , depending on the processing schedule. Fine carbide particles, microalloyed precipitates and austenitic islands played important roles in defining the mechanism of grain refinement that involved retarding conventional ferrite recrystallization and ferrite grain growth. With regard to the intercritical deformation, warm-deformation followed by annealing is a simpler process to control in the rolling mill; however, the need for high-power rolling mill and controlled annealing facility imposes industrial challenges.

The 1897 Great Shillong earthquake revealed considerable seismic susceptibility in Guwahati City, such as soil liquefaction, landslides, and surface fissures. In an attempt to quantify the seismic vulnerability of the city based on geological, seismological, and geotechnical aspects concerning seismic site characterization, in-depth analysis was performed using a microtremor survey with recordings of five small to moderate magnitude (4.8 ≤ m b  ≤ 5.4) earthquakes that occurred in 2006 and geotechnical investigations using the Standard Penetration Test (SPT). Additionally, the basement topography was established using vertical electrical resistivity sounding and selected drill-hole information. Region-specific relationships are derived by correlating the estimated values of predominant frequency, shear-wave velocity, and basement depth indicating conformity with the predominant frequency distribution and the basin topography underlain by a hard granitic basement. Most parts of the city adhere to the predominant frequency range of 0.5–3.5 Hz, setting aside areas of deep sediment fills or hilly tracts, suggesting that the existing moderate-rise RC buildings in the territory are seismically vulnerable. Furthermore, the geotechnical assessment of the soil liquefaction potential reveals widespread susceptibility across the terrain. Eventually, a site classification map of the city is prepared following the National Earthquake Hazard Program (NEHRP) provision. The average site amplification factor from geotechnical modeling for site class D is about 3 in the frequency range of 2–4 Hz. In addition, earthquake data yield an average site amplification factor of 4–6 in the frequency range of 1.2–5.0 Hz at the seismic stations located in site class E and F. High site amplifications of around 5.5 and 7.5 at 2 Hz, respectively, are observed at AMTRON and IRRIG seismic stations, which are located in the proximity of Precambrian rocks, indicating probable basin edge effects—scattering and diffraction of incident energy. Interplay of dispersed valleys surrounded by small hillocks in the study region is likely to induce micro-basin effects where the sediment thickness/depth vis-à-vis predominant frequency and basin geometry in conjunction play pivotal roles in the augmentation of site response.

High velocity oxy-fuel (HVOF) spray process has grown into a well-accepted industrial technology for obtaining coatings resistant to significant surface degradation processes. In the present study, HVOF process was used to deposit Ni-based hardfacing NiCrFeSiB alloy powder on kinds of boiler tube steels designated as SA210 grade-A1, SA213-T11, and SA213-T22. The microstructures and several properties of the as-sprayed coatings have been investigated. Thermocyclic oxidation studies were performed in static air at 900 °C. NiCrFeSiB-coated steels showed slow oxidation kinetics and considerably lower weight gains than that of uncoated steels. The superior performance of NiCrFeSiB coatings can be attributed to continuous and protective thin oxide scale of amorphous SiO 2 and Cr 2 O 3 formed on the surface of the oxidized coatings. The combined technique of x-ray diffraction, scanning electron microscopy, energy dispersive x-ray analysis, and electron probe microanalysis are used to characterize reaction products of the oxidized surfaces.

The probable mitigation and management issues of seismic hazard necessitate seismic microzonation for hazard and risk assessment at the local level. Such studies are preceded with those at a regional level. A comprehensive framework, therefore, encompasses several phases from information compilations and data recording to analyses and interpretations. The state-of-the-art methodologies involve multi-disciplinary approaches namely geological, seismological, and geotechnical methods delivering multiple perspectives on the prevailing hazard in terms of geology and geomorphology, strong ground motion, site amplification, site classifications, soil liquefaction potential, landslide susceptibility, and predominant frequency. The composite hazard is assessed accounting for all the potential hazard attributing features with relative rankings in a logic tree, fuzzy set or hierarchical concept.

This study investigates the induction hardening characteristics and wear performance of 45C8 carbon steel and EN47 spring steel. Optical microstructures of hardened steels revealed that martensite formed due to the quenching (faster than critical cooling) involved in induction hardening. The grain size of hardened EN47 steel was finer, and hardness was higher than that of carbon steel due to its higher carbon content and alloying elements. The depth of the hardened layer in both steels was almost equal (~1.1 mm). Slurry erosive wear tests were carried out using a slurry pot tester to characterize the steel’s induction hardening. The slurry erosion resistance, assessed by cumulative mass loss, of the hardened EN47 spring steel was higher than the carbon steel due to its high hardness and toughness. Predominantly, the craters, microcutting, and plowing eroded the material for unhardened steels, while indentations and pullouts were also responsible for the material removal from the hardened steels. From the fractographic analysis, the ductile mode of erosion for unhardened steel and mixed (ductile + brittle) erosion mode for hardened steel can be established.

Perfluoropolyethers (PFPEs) are widely used as hard disk lubricants for protecting carbon overcoat reducing friction between the hard disk interface and the head during the movement of head during reading and writing data in the hard disk. Due to temperature rise of PFPE Zdol lubricant molecules on a DLC surface, how polar end groups are detached from lubricant molecules during coating is described considering the effect of temperatures on the bond/break density of PFPE Zdol using the coarse-grained bead spring model based on finitely extensible nonlinear elastic potential. As PFPE Z contains no polar end groups, effects of temperature on the bond/break density (number of broken bonds/total number of bonds) are not so significant like PFPE Zdol. Effects of temperature on the bond/break density of PFPE Z on DLC surface are also discussed with the help of graphical results. How bond/break phenomenonaffects the end bead density of PFPE Z and PFPE Zdol on DLC surface is discussed elaborately. How the overall bond length of PFPE Zdol increases with the increase of temperature which is responsible for its decomposition is discussed with the help of graphical results. At HAMR condition, as PFPE Z and PFPE Zdol are not suitable lubricant on a hard disk surface, it needs more investigations to obtain suitable lubricant. We study the effect of breaking of bonds of nonfunctional lubricant PFPE Z, functional lubricants such as PFPE Zdol and PFPE Ztetrao, and multidented functional lubricants such as ARJ-DS, ARJ-DD, and OHJ-DS on a DLC substrate with the increase of temperature when heating of all of the lubricants on a DLC substrate is carried out isothermally using the coarse-grained bead spring model by molecular dynamics simulations and suitable lubricant is selected which is suitable on a DLC substrate at high temperature.