Surface finish greatly affects the friction, wear, corrosion, heat transfer and lubrication properties of internal surfaces which find wide applications in medical, automobile, aerospace and mould ...and die industries. However, improving the internal surface finish is extremely challenging due to the restricted tool accessibility of conventional manufacturing processes. This paper develops a novel magnetic polishing tool to deterministically polish internal surfaces. Repeatability tests, single point polishing experiments and gap variation experiments are conducted to evaluate the performance of the proposed polishing tool. Experimental results substantiate the good repeatability and localized polishing capability with a material removal rate of 15 μm/min and achievable surface roughness of 0.258 μm Ra. Furthermore, a theoretical model is developed to reveal the material removal mechanism based on the contact mechanics model and sliding wear theory. The developed model can successfully predict the two-dimensional and three-dimensional polished profiles under different gaps which are defined by the distance between the externally driven magnet and the outer surface of the workpiece. The localized polishing capability is, for the first time, achieved in internal surface finishing and the theoretical study establishes a novel framework for modelling the polished profile evolution in pressure-copying polishing processes.
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•Localized polishing capability is for the first time achieved in internal finishing.•Material removal rate reaches 15 μm/min and surface roughness improvement is 88%.•Gap is the dominant factor influencing material removal rate.•A material removal model is developed based on contact mechanics and wear theory.
We report first principles calculations of the electronic structure of monolayer 1H-MX
2
(M = Mo, W; X = S, Se, Te), using the pseudopotential and numerical atomic orbital basis sets based methods ...within the local density approximation. Electronic band structure and density of states calculations found that the states around the Fermi energy are mainly due to metal
d
states. From partial density of states we find a strong hybridisation between metal
d
and chalcogen
p
states below the Fermi energy. All studied compounds in this work have emerged as new direct band gap semiconductors. The electronic band gap is found to decrease as one goes from sulphides to the tellurides of both Mo and W. Reducing the slab thickness systematically from bulk to monolayers causes a blue shift in the band gap energies, resulting in tunability of the electronic band gap. The magnitudes of the blue shift in the band gap energies are found to be 1.14 eV, 1.16 eV, 0.78 eV, 0.64, 0.57 eV and 0.37 eV for MoS
2
, WS
2
, MoSe
2
, WSe
2
, MoTe
2
and WTe
2
, respectively, as we go from bulk phase (indirect band gap) to monolayer limit (direct band gap). This tunability in the electronic band gap and transitions from indirect to direct band make these materials potential candidates for the fabrication of optoelectronic devices.
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•N,N′-Diglycidyl-1,6-hexanediamine acts as excellent corrosion inhibitor for copper.•The adsorption of the inhibitor followed Langmuir isotherm.•The inhibitor shows mixed type ...behavior with cathodic predominance.•SEM and FTIR studies confirmed the inhibitor adsorption.•DFT studies show that the inhibitor shows excellent ability of adsorption.
A bifunctional N-glycoside namely N,N′-Diglycidyl-1,6-hexanediamine (DHA) was synthesized by the facile reaction of 1,6-hexamethylene diamine and glucose and its corrosion inhibition behavior was evaluated on copper in 3.5% NaCl solution for the first time. A detailed electrochemical study using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electrochemical microscopy (SECM) was carried out to understand the mechanism of corrosion inhibition shown in the present work. The DHA showed a corrosion inhibition efficiency of >95% at a concentration of 0.27mmolL−1. The adsorption of DHA over copper surface followed the Langmuir isotherm. The surface and the electrochemical reactivity of the inhibitor-modified Cu samples in 3.5% NaCl solution was examined by the SECM technique, demonstrating the formation of a thin inhibitor film with exposure/immersion time in solution containing DHA molecules. The results of surface analysis using scanning electron microscopy (SEM) and ATR-IR spectroscopy supported the adsorption of inhibitor molecules over copper surface. The quantum chemical parameters and molecular electrostatic potential were evaluated using density functional theory, further supported the experimental findings.
Rapid increment in fossil-derived single-use plastic disposal has led to human-made plastic mountains and leading to ecological imbalance. Therefore, the development of alternative environmentally ...friendly, biodegradable, and biobased plastics using lignocellulosic biomass renders sustainability. Lignocellulosic biomass offers an unprecedented opportunity to produce renewable fuels, chemicals, and materials for the replacement of fossils-based derivatives. The present review comprehensively delineates the potential of lignocellulosic biomass to produce biodegradable and recyclable plastics and plastic composites. Initially, various available pretreatment methods for the deconstruction of natural recalcitrance for fuel and chemical production are summarized, along with the challenges and scope of the integrated biorefinery approach. Energy chemicals such as ethanol, hydrogen produced under biorefinery approach may serve as precursor for bioplastics productions for sustainable bio future. Recyclable and biodegradable polymers such as polyglycolic acid, polyhydroxyalkanoates, polylactic acid, polybutylene succinate, polyvinyl alcohol, biobased polyethylene, biobased polyethylene terephthalate and cellulose acetate have been critically reviewed. Furthermore, the limitations, hurdles, and future scope of commercially available biorefinery industries are deliberated. Thus, technical development and integration in current biorefinery could promote the economical production of biobased biodegradable and recyclable plastics, simultaneously addressing waste biomass utilization constraints.
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•Lignocellulosic biomass (LCB) is a potential renewable feedstock for biopolymer.•Low-cost and efficient pretreatment is essential to overcome the recalcitrance.•LCB-derived polymer is either biodegradable (e.g., PHA) or recyclable (e.g., Bio-PE).•Biopolymer can be reinforced with cellulose, lignin, graphene and natural fibers.•Integration with biofuel production is recommended for economics and sustainability.
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•Conductive NPs potential to improve AD performance was critically discussed.•Impact of different NPs and sizes on AD biogas quantity and quality are elucidated.•The interactions of ...AD microorganisms and DIET with the aid of NPs were reviewed.•The role of NPs in biochemical pathways direction and metabolites utilization are covered.
Anaerobic digestion (AD) is a biochemical process that converts waste organic matter into energy-rich biogas with methane as the main component. Addition of electric electro-conductive, such as that nanoparticles (NP), has been shown to improve biogas generation. Interspecies electron transfer and direct interspecies electron transfer (DIET) using conductive materials is one of the mechanisms responsible for observed increases in CH4. This article discusses the effect of the type and size of electro-conductive NPs on improving microbial degradation within AD systems, as well as the effect of electro-conductive NPs on microbial community shifts and syntrophic metabolism. Limitations and future perspectives of using NPs in an AD system is also discussed.
The marine plastic pollution has drastic effect on marine species. The importance in environmental issues increases the demand to develop a significant technology which does not burden the marine ...environment or marine life forms. To mitigate the foreseen problems of micro and nanoplastic contamination, different biotechnological solutions has to be considered. Microbial communities exposed to plastic contaminated sites can adapt and form dense biofilms on the plastic surface and produce active catalytic enzymes. These enzymes can be able to degrade the synthetic polymers. In view of their high catalytic activity, microbial enzymes can be applicable for the degradation of synthetic polymers. This review highlights the toxicity of micro and nanoplastics on marine organisms, biodegradation of plastics and futuristic research needs to solve the issues of plastic pollution in marine environment.
Schematic illustration of plastic biodegradation by microorganisms. Display omitted
•Impacts of micro and nanoplastics on the ecological function of marine organisms•Importance of marine microbial enzymes as possible solution for plastic pollution•Futuristic research needs to develop biotechnological solution for plastic degradation.
Conceptualizing waste biorefinery for recovery of value added products. Display omitted
•Resource recovery of bioenergy and platform chemicals from waste.•Biorefinery as a sustainable approach for ...waste mining.•Exploitation of waste would enhance biorefinery competitiveness & social acceptance.
Increased urbanization worldwide has resulted in a substantial increase in energy and material consumption as well as anthropogenic waste generation. The main source for our current needs is petroleum refinery, which have grave impact over energy-environment nexus. Therefore, production of bioenergy and biomaterials have significant potential to contribute and need to meet the ever increasing demand. In this perspective, a biorefinery concept visualizes negative-valued waste as a potential renewable feedstock. This review illustrates different bioprocess based technological models that will pave sustainable avenues for the development of biobased society. The proposed models hypothesize closed loop approach wherein waste is valorised through a cascade of various biotechnological processes addressing circular economy. Biorefinery offers a sustainable green option to utilize waste and to produce a gamut of marketable bioproducts and bioenergy on par to petro-chemical refinery.
In the present research work, an effort has been made to examine the effect of the ERNiCrCoMo-1 filler on solidification mechanism, microstructural characterization, welded joint integrity, and ...residual stresses of the dissimilar welded joint (DWJ) of martensitic grade P92 steel and Ni-based superalloy Inconel 617 for advanced ultra-supercritical (A-USC) power plant application. Weld joints have been fabricated for V groove geometry by using the multipass gas tungsten arc welding (GTAW) process. The multiple aspects of the welded joint structural integrity have been tested by performing the tensile test, microhardness tests and Charpy impact test. The ERNiCrCoMo-1 weld solidified in austenitic mode with columnar and cellular dendrites in the interior region, while columnar dendrites were observed near the interface region. The unmixed zone (UZ) formation was noticed at the ERNiCrCoMo-1 filler weld and P92 steel interface, while the UZ gets eliminated at Inconel 617 interface. The microstructural observation near the interface showed that migrated grain boundaries were observed frequently near the lower region of the weld metal (WM), while at the interface of the P92 steel and ERNiCrCoMo-1 filler welds, higher density of soft
δ
ferrite patches for the capping and backing passes were observed. The energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD) results confirmed the presence of the Cr- and Mo-enriched M
23
C
6
precipitates, Mo-enriched M
6
C and Ti-enriched Ti(C, N) precipitates in the WM. Acceptable mechanical properties were obtained at room temperature. The Charpy impact toughness (CIT) was observed 98 ± 5 J and 108 ± 3 J for WM with V notch at the top and root region, respectively. The dramatic reduction in CIT was after the postweld heat treatment (PWHT) was attributed to the evolution of the carbide particles in interdendritic areas. Tensile strength results of the cross-weld specimen showed the tensile strength value marginally lower than the P92 steel but significantly lower than the Inconel 617 base metal in both as-welded (AW) and PWHT condition along with fracture in the week region of P92 steel. The failure from the region of P92 steel instead of the ERNiCrCoMo-1 filler WM confirmed that the welded joint was safe for A-USC power plants boiler application. A significant heterogeneity in microhardness was seen along the weldments with a peak hardness of 445 ± 8 in P92 CGHAZ and a lower hardness of 181 HV in the peninsula. The increase in microhardness of the WM as a result of PWHT was attributed to the evolution of the carbide particles in the WM. Through thickness residual stresses variation was also measured for both WM and HAZ region and the effect of the PWHT on the magnitude and nature of the residual stresses were also performed. Hence the work provides insight into welding procedure development, microstructural evolution in the WM and HAZ, variation in mechanical properties, and residual stresses variation for the welded joint of P92 steel and Inconel 617 alloy.
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•Gas sensors and its genera discoursed prudently.•Various gas sensing mechanism illustrated aptly.•Cited the prominence of recurrent review on volatile organic compounds, namely ...Toluene, Ethanol, Formaldehyde.•Analyzed the current trends and scope of detection of various volatile organic compound using sensors.•Overviewed the significance of utilizing nanomaterials in gas sensing.
The presence of toxic and harmful gases utterly dangers human health and environmental well-being. Selective detection of these gases is immediately required to meet the demands of society. A promising and presently thriving area for monitoring volatile organic compounds (VOCs) and combustible gases stems from the evolution of detection strategies meld with metal-oxide-based nano-materials. Even though the prevailing literature in nanoscience covers numerous reports on chemical sensing merged with nanotechnology, a few have focused on gas detection. This review takes the lead to study, categorize, and inspect the progressive gas detection approaches accessible in literature. Each gas sensing technique is analyzed based on the detection principle and is reviewed on various aspects such as gas detection, sensitivity, response /recovery time, sensor parameters, procedural complexity, detection variables, and sensor characteristics. Furthermore, this investigation serves as a valuable reference for researchers to recognize the mechanism behind the gas sensor’s fundamental facets. Concisely, this review elucidates the state of this field and induces/propels further research in this field.
