<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

World University root node

Mechanical Engineering

(SoE) School of Engineering

Fulltext

Scientific Reports

Author Correction: Novel hybrid method to additively manufacture denser graphite structures using Binder Jetting (Scientific Reports, (2021), 11, 1, (2438), 10.1038/s41598-021-81861-w)

The food and medical sectors have to abide by the strict regulations of quality control and this requires strict monitoring of various types of chemicals and pathogens. These requirements have brought laurels to the field of biosensing to develop the most capable sensors to detect a target property instantly as well as precisely. Biosensors integrated with the nanotechnological approach make them simple and tiny in size, which also provides a point-of-care platform. The last two decades have been devoted to developing different biosensors using nanoscale materials due to their sensitive and unique properties. Search is on, for the combination of materials for biosensors, which can make them multipurpose, inexpensive, and eco-friendly. The molecules or analytes can be detected through different working principles of biosensors. Biosensing is a wide area and several biosensors exist each with its working principles and/or sometimes a combination of two–three principles making them a hybrid sensor. This book chapter is aimed to revisit these working principles considering the growing use of newer nanomaterials (nanoparticles, nanowire, and nanosheet) in use for the development of biosensors. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Materials Horizons: From Nature to Nanomaterials

Nanomaterials Based Biosensing: Methods and Principle of Detection

The stepwise hydration of clay minerals has been observed repeatedly in studies, but the underlying mechanism remains unclear. Previous numerical studies confirmed the presence of one-water layer (1W) and two-water layer (2W) hydration states. However, the undisturbed transition between these hydration states has never been captured. Using molecular dynamics simulation, this study (i) simulated for the first time the free 1W–2W transition during clay hydration and (ii) identified the underlying mechanism to be the detachment of cations from the clay surface and the formation of a shell of water molecules around the cation. The swelling dynamics of clay was found to be affected by the clay charge, clay mineralogy, and counterions through complex cation–clay interactions, cation hydration capacity, and cation migration rate. © 2022 The Authors. Published by American Chemical Society

ACS Omega

Clay Swelling: Role of Cations in Stabilizing/Destabilizing Mechanisms

A novel cutting strategy of machining microstructure surface with the multi-tip diamond tool based on the force modulation approach is proposed in this paper. The multi-tip diamond tool with periodic sinusoidal microstructures was prepared by focused ion beam technique. The influence of applied cutting forces on the depths of cut and material removal states was investigated experimentally. MD simulations revealed a significant phenomenon of no material side flow when using the multi-tip diamond tool cutting on single crystal copper substrate. The movement of stacking faults, Lomer-Cottrell locks and Hirth locks jointly governed the formation mechanism of machined surface. To demonstrate the feasibility and effectiveness of this proposed cutting strategy, the fabrication of periodic sinusoidal microstructures under constant forces was successfully realized on the microsphere surface. Furthermore, three-dimensional sin-shaped ripples required variable forces controlling were achieved with high-precision surface quality. The cross-sectional topography of obtained ripples matched the geometry of used MTD tool quite well. In particular, the processing parameters, including the time period of loading forces and cutting speeds, determine the expected wavelength of ripples and play a central role in the surface machining accuracy. © 2021 The Society of Manufacturing Engineers

Journal of Manufacturing Processes

Fabrication of three-dimensional sin-shaped ripples using a multi-tip diamond tool based on the force modulation approach

Metamaterials, an artificial periodic two- or three-dimensional configuration, can change propagation characteristics of electromagnetic waves (i.e., reflection, transmission, absorption). The current challenges in the field of metamaterial coatings are their manufacturing in a large-scale and large-length scale. There is a clear need to enhance process technologies and scalability of these. Thermal spraying is a method used to deposit small- to large-scale coatings where the sprayed layer is typically formed by the successive impact of fully or partially molten particles of a material exposed to various process conditions. This work aims to investigate the feasibility to manufacture large scale metamaterial coatings using the thermal spray technique and examine their response to solar radiation. Two types of coatings namely, Cr2O3 and TiO2, were deposited onto various substrates (e.g., steel, aluminium, glass, indium tin oxide (ITO)–coated glass) with a fine wire mesh (143 µm and 1 mm aperture sizes) as the masking sheet to manipulate the surface pattern using suspension high-velocity oxy-fuel thermal spraying (S-HVOF) and atmospheric plasma-sprayed (APS) methods, respectively. Post deposition, their responses subjected to electromagnetic wave (between 250 and 2500 nm or ultraviolet (UV)-visible (Vis)-infrared (IR) region) were characterised. The additional microstructural characterisation was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), three-dimensional profilometry, and optical spectroscopy. It is demonstrated that through novel application of thermal spray techniques, large-scale manufacturing of metamaterial coating is possible, and such material can affect electromagnetic wave propagation. Comparison between Cr2O3 and TiO2 coatings on aluminium substrates showed reduced three orders of reduced reflectance for Cr2O3 coatings (for 1-mm aperture size) throughout the spectrum. It was concluded that for a similar bandgap, Cr2O3 coatings on aluminium substrate will yield improved optical performance than TiO2 coating, and hence more useful to fabricate opto-electronic devices. Graphical abstract: [Figure not available: see fulltext.] © 2021, The Author(s).

Emergent Materials

Large-scale manufacturing route to metamaterial coatings using thermal spray techniques and their response to solar radiation

Progress made by materials scientists in recent years has greatly helped the field of ultra-precision manufacturing. Ranging from healthcare to electronics components, phenomena such as twinning, dislocation nucleation, and high-pressure phase transformation have helped to exploit plasticity across a wide range of metallic and semiconductor materials. One current problem at the forefront of the healthcare sector that can benefit from these advances is that of bacterial infections in implanted prosthetic devices. The treatment of implant infections is often complicated by the growth of bacterial biofilms on implant surfaces, which form a barrier that effectively protects the infecting organisms from host immune defenses and exogenous antibiotics. Further surgery is usually required to disrupt the biofilm, or to remove the implant altogether to permit antibiotics to clear the infection, incurring considerable cost and healthcare burdens. In this review, we focus on elucidating aspects of bactericidal surfaces inspired by the biological world to inform the design of implant surface treatments that will suppress bacterial colonization. Alongside manufacturing and materials related challenges, the review identifies the most promising natural bactericidal surfaces and provides representative models of their structure, highlighting the importance of the critical slope presented by these surfaces. The scalable production of these complex hierarchical structures on freeform metallic implant surfaces has remained a scientific challenge to date and, as identified by this review, is one of the many 21st-century puzzles to be addressed by the field of applied physics. © 2021 Author(s).

Applied Physics Reviews

Bactericidal surfaces: An emerging 21st-century ultra-precision manufacturing and materials puzzle

The high entropy alloys have become the most intensely researched materials in recent times. They offer the flexibility to choose a large array of metallic elements in the periodic table, a combination of which produces distinctive desirable properties that are not possible to be obtained by the pristine metals. Over the past decade, a myriad of publications has inundated the aspects of materials synthesis concerning HEA. Hitherto, the practice of HEA development has largely relied on a trial-and-error basis, and the hassles associate with this effort can be reduced by adopting a machine learning approach. This way, the “right first time” approach can be adopted to deterministically predict the right combination and composition of metallic elements to obtain the desired functional properties. This article reviews the latest advances in adopting machine learning approaches to predict and develop newer compositions of high entropy alloys. The review concludes by highlighting the newer applications areas that this accelerated development has enabled such that the HEA coatings can now potentially be used in several areas ranging from catalytic materials, electromagnetic shield protection and many other structural applications. © 2021, The Author(s).

Emergence of machine learning in the development of high entropy alloy and their prospects in advanced engineering applications

The term “nature-inspired” is associated with a sequence of efforts to understand, synthesize and imitate any natural object or phenomenon either in a tangible or intangible form, which allows us to obtain improved insights into nature. Such inspirations can come through materials, processes, or designs that we see around us. Materials, as opposed to processes and designs found in nature, are tangible and can readily be used without engineering efforts. One such example is that of an aquaporin that is used to filter water. The scope of this work in nature-inspired materials is to define, clarify, and consolidate our current understanding by reviewing examples from the laboratory to industrial scale to highlight emerging opportunities. A careful analysis of “nature-inspired materials” shows that they possess specific functionality that relies on our ability to harness particular electrical, mechanical, biological, chemical, sustainable, or combined gains. © 2021, The Author(s).

NPG Asia Materials

Nature-inspired materials: Emerging trends and prospects

Thermal spraying is a scalable surface engineering technique used to add or to restore functionality of a solid surface by applying a coating. Examples of this include protection against wear, erosion, abrasion, and heat. In a specific sense, thermal spraying is particularly used to deposit thermal barrier coatings (TBCs) which finds use in transportation, power generation and automotive sector. As being a surface technique, thermal spraying much like other surface coating techniques can avoid the use of excessive bulk materials and in turn offers longevity to the life of the component, so it already contributes to the reduction of global warming by virtue of avoiding the use of excessive scarce materials and improving fuel efficiency. In terms of its contribution to the cause of global warming, thermal spraying stands in sharp contrast to the energy-intensive processes such as melting, casting, extrusion and welding. With the rise of additive manufacturing, it is possible to use thermal spray to complement that process in many ways and “cold spray additive manufacturing” (CSAM) is already gaining popularity. The thermal spraying technique relies on using selective types of gases—hydrogen being one of them and few types of metals/alloys which are now classed as critical raw materials due to them being on the supply risk register. Efforts to consider recycling and reuse and to find alternatives to these are very timely to continue drawing the advantage of thermal spraying being a relatively green technique. In particular, the green energy initiatives and the drive to develop energy storage and battery technologies could challenge the supply of raw materials such as hydrogen gas and rare earth elements. This underlines the research and development need for alternate materials and processes to address the issue of climate change which is the major focal point of the COP 26 Summit at Glasgow in 2021. The combination of digital technologies and thermal spray coatings will reduce gas, powder and power consumption, which will make this manufacturing process even greener. © 2021, The Author(s).

Role of thermal spray in combating climate change

Friction stir spot welding (FSSW) is a solid-state welding process, wherein the properties of a weld joint are influenced by the state of friction and localised thermodynamic conditions at the tool-workpiece interface. An issue well-known about FSSW joints is their lack of reliability since they abruptly delaminate at the weld-faying interface (WFI). This study explores the origins of the delamination of multiple lap welded aluminium alloy (AA 5754-H111) sheets joined by FSSW at different rotational speeds typically used in industry. Experimental techniques such as the small punch test (SPT), Vickers hardness test, Scanning Electron Microscopy (SEM), Scanning Acoustic Microscope (SAM), Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX) and Frequency-Modulated Kelvin Probe Force Microscopy (FM-KPFM) were employed. The experimental results revealed that a complex interplay of stress-assisted metallurgical transformations at the intersection of WFI and the recrystallised stir zone (RSZ) can trigger dynamic precipitation leading to the formation of Al3Mg2 intermetallic phase, while metallic oxides and nanopits remain entrapped in the WFI. These metallurgical transformations surrounded by pits, precipitates and oxides induces process instability which in turn paves way for fast fracture to become responsible for delamination. © 2021 The Authors

International Journal of Machine Tools and Manufacture

In-depth microscopic characterisation of the weld faying interface revealing stress-induced metallurgical transformations during friction stir spot welding

In this paper, molecular dynamic (MD) simulation was employed to simulate the AFM tip-based nanoscratching process on multilayer graphene to investigate graphene deformation and coefficient of friction (COF). MD Simulation results showed cross-linking structures were created at the interface of two-layer graphene during nanoindentation and nanoscratching. The loading force had a characteristic of a periodic wave crest-trough transition. The COF of the diamond tip fluctuated at around 0.15 during nanoscratching process. © 2021 Proceedings of the 21st International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2021. All rights reserved.

Proceedings of the 21st International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2021

Molecular dynamics simulation of AFM tip-based nanoscratching of multi-layer graphene

GaAs is a hard, brittle material and its cutting at room-temperature is rather difficult, so the work explored whether hot conditions improve its cutting performance or not. Atomic force microscope (AFM) tip-based hot machining of the (0 1 0) oriented single crystal GaAs was simulated using molecular dynamics (MD). Three representative temperatures 600 K, 900 K and 1200 K (below the melting temperature of ~1511 K) were used to cut GaAs to benchmark against the cutting performance at 300 K using indicators such as the cutting forces, kinetic coefficient of friction, cutting temperature, shear plane angle, sub-surface damage depth, shear strain in the cutting zone, and stress on the diamond tip. Hotter conditions resulted in the reduction of cutting forces by 25% however, the kinetic coefficient of friction went up by about 8%. While material removal rate was found to increase with the increase of the substrate temperature, it was accompanied by an increase of the sub-surface damage in the substrate. Simulations at 300 K showed four major types of dislocations with Burgers vector 1/2<110>, 1/6<112>, <0–11> and 1/2<1–12> underneath the cutting zone and these were found to cause ductile response in zinc-blende GaAs. Lastly, a phenomenon of chip densification was found to occur during hot cutting which referred to the fact that the amorphous cutting chips obtained from cutting at low temperature will have lower density than the chips obtained from cutting at higher temperatures. © 2021

Materials Science in Semiconductor Processing

Molecular dynamics simulation of AFM tip-based hot scratching of nanocrystalline GaAs

Insights into the biological channels and synthetic pore-forming assemblies have elucidated many fundamental aspects of selective water and solute transport over the last few decades. This has led to the development of novel technologies with unique selectivity and permeability. In terms of membrane separation technology, this development has proceeded by adapting either of two approaches: (i) one where biological channel proteins are reconstituted in suitable materials mimicking the biological bilayer membrane and (ii) one where selective transport is mimicked in synthetic structures. The development of water filtration membranes in the former approach takes advantage of aquaporin proteins as representative building blocks and that of carbon nanotubes and molecular pore-forming assemblies in the latter approach. The first approach is often referred to as the field dominated by biomimetic membranes and the latter referred to as artificial water channels. In this study, a bibliometric analysis was conducted to investigate trends in these two areas based on growing publication trends, peer-reviewed journal selection, countries, institutions, authors, and collaborative networks. A total of 3199 records available from Scopus between 1962 and 2021 were extracted and analyzed. The results showed strong international collaborations and highlighted leading researchers and hubs of excellence in these two areas. This is very timely considering that the UN climate change conference (COP26) in Glasgow, UK later this year will bring focus to the global need for water treatment technologies. This work can serve as a quick reference for early-career researchers and industries working in the area of membrane development for water purification/filtration. © 2021, The Author(s).

npj Clean Water

A bibliometric study on biomimetic and bioinspired membranes for water filtration

This paper proposes an analytical model for predicting grinding-induced sub-surface damage depth in a silicon wafer. The model integrates the dislocation kinetics for crack initiation and fracture mechanics for crack propagation for the first time. Unlike other conventional models, the proposed model considers the effects of strain rate on damage depth and the dynamically changing metastable phase change properties. The model is verified by grinding experiments and a comparison of theoretical and experimental results shows a good quantitative agreement. It is found that increasing grinding speed and decreasing depth of cut cause a higher strain rate so as to enhance material brittleness, which is favorable to achieving low sub-surface damage. These findings will pave a way towards optimizing the grinding parameters and greatly improving the production efficiency of hard and brittle materials. © 2021 CIRP