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There has been a continuous downfall in equipping the Primary Health Centres (PHCs) with infrastructure, facilities, and workforce to provide basic minimum primary healthcare services to the underserved population in the Indian context. The main goal of this research is to look at the infrastructure and manpower in a sample of PHCs in the Kanpur district of Uttar Pradesh, India. The interview template exclusively for Product-Service System (PSS) by Singapore University of Technology and Design-Massachusetts Institute of Technology (SUTD-MIT) was used to study randomly selected samples of 51 PHCs. The data were examined using the Indian Public Health Standards (IPHS) of the Indian government. Some of the key findings included the lack of workforce and their commitment, shortage of space, electricity, and water supply. To find a solution for the found lacunae, this article also discusses about the functioning of Mobile Hospitals (MHs) depending upon the contexts and thus extracting lessons for a new intervention in the primary health care system delivery model. Finally, a new healthcare delivery model in the form of a mobile Primary Health Centre (mPHC) is proposed based on the field study and the synthesis of historical literature on MH. [ABSTRACT FROM AUTHOR]

The pandemic, which can be envisioned as a collective nightmare for humanity, was contemplated in July 2020 from the author's residence. Everyone, regardless of social status, had difficult times in their personal and professional lives. Although we researchers are concerned and responsible for enhancing both paradigms of humanity with the help of innovations in emergency situations, this study is based on my experiences pursuing a PhD at the time of Covid-19 in the domain of healthcare infrastructure and service design. The PhD aims to design, develop, and deploy a cost-effective collapsible mobile Primary Health Centre (mPHC) unit specifically tailored for low-resource settings. This report will take readers on an unknown journey through the process of conducting design-led research and disseminating insights for future researchers. [ABSTRACT FROM AUTHOR]

Wheelchair (WC) design elements are subjected to the accessibility and assistive needs of a person with locomotor disability. In order to pursue a holistic design for a stairclimbing WC, there is a need for literature review on WC functions reported for both stair climbing and plane surface movement. A total of 112 Research articles are reviewed for the purpose of extracting the relationship between WC design elements and the functions associated with them. Stairclimbing technologies are reviewed for their technological assessment in terms of functional elements associated with stairclimbing. Cross-functional mapping between functional elements and their dominant function is performed. Heat map for primary user needs and associated design elements is generated from cross mapping. A design gap for user's functional needs is indicated from the review of literature on prototypes and products of WC. The literature in stairclimbing technology is primarily focussed on stair climbing capability and not on the other functional needs, such as safety, ride comfort, seat comfort, manoeuvrability, etc. For attaining the goal of an effective rehabilitation, it is important to design and develop an assistive technology that can provide maximum accessibility and functioning for a person with disability. In case of locomotor disability, wheelchair (WC) is the most empowering tool that can assist people in both accessibility and activities of daily living. This review of literature was conducted to draw out the functions fulfilled by a WC, such as safety, comfort, propulsion for its users and the associated WC elements like seat, wheels, backrest, etc., that are required to fulfil those functions. WC being the most important technological intervention in the life of a person who cannot walk should be designed with the highest level of empathy. Therefore, each and every aspect of the user's physical and emotional needs should be catered up to the limits of engineering design. The research on stair climbing technologies has also grown exponentially, fuelled by technological growth in engineering mechanisms, ambient awareness sensors, actuators, etc. The review attempts to envelop such technologies and consolidate them on the basis of their capabilities and efficacies. The virtue of stair climbing has been realized through some novel and innovative mechanisms reviewed in this article that can be integrated with the research in field of functional elements required to carry out primary functions of a disabled person, such as safety, comfort, intuitiveness, etc. This review can help in coupling both of them in a more rational way where a designer who is designing the technology is more empathetic towards the design for accessibility. It can also help user in becoming more confident towards adapting a new assistive technology. [ABSTRACT FROM AUTHOR]

In the current study, electro-deposition of hybrid coatings consisting of Cr simultaneously reinforced with nano-scale 3 mol% yttria-stabilized zirconia (YSZ) along with hexagonal boron nitride (Cr-YSZ-BN), graphene (Cr-YSZ-Gr), and diamond (Cr-YSZ-D) was performed using an environmentally-benign trivalent Cr bath. Abrasive wear with ploughing for scratch test is recognized as the dominant wear mechanism in coatings; on increasing the scratch speed, gross spallation occurs in the BN reinforced coatings. While graphene and diamond were strongly adherent to the substrate with no signs of delamination. During fretting, oxidative and three-body abrasive wear in wedge formation mode with severe crack networking was observed in Cr-YSZ-BN. Micro-ploughing was active with intermittent cracking in Cr-YSZ-Gr coatings, indicating lower wear (via solid-lubrication by graphene). Diamond added coating, on the other hand, exhibits fewer cracks with ploughing. High hardness and elastic modulus with a maximum of ~26 GPa and 245 GPa, respectively, were obtained for Cr-YSZ-D coating with a minimum wear rate of ~3.5×10−11 m3/Nm (fretting) and 3.8×10−5 mm3/Nm (scratching). Further, rigid sp3 hybridization of carbon atoms in Cr-YSZ-D leads to the strong interlocking between Cr matrix and diamond, thereby lowering the wear damage of the coating system. The unique combination and uniform dispersion of YSZ and diamond particles displayed enhanced friction and wear resistance (k ~ 1.4×10−3), primarily due to the inherent high hardness of diamond and matrix strengthening by nano and micro-scale particles. Therefore, Cr-YSZ-D coating system emerges out as a highly robust coating capable of providing enhanced damage tolerance towards wear for various tribological applications. • Synergistic YSZ reinforcement with BN, graphene, and diamond in Cr-matrix. • Reduced crystallite size (~15 nm) and high dislocation density (~1011 cm-2) in reinforced coatings. • High compressive residual stresses (~720–1230 MPa) in hybrid coatings. • High fretting damage tolerance (wear rate of ~3.5 × 10–11 m3/Nm) in Cr-YSZ-D hybrid coating. • Low micro-scratch damage (wear rate of 3.8 × 10-5 mm3/Nm) in Cr-YSZ-D hybrid coating. [ABSTRACT FROM AUTHOR]

Mineral oil–based lubricants play an important role to serve industrial lubrication and cooling requirements. However, these oils are environmentally unacceptable due to their negative impact on human health and environmental ecology. The current research focuses on generating an eco-friendly oil which has enhanced lubrication properties. In this work, a four-ball tribometer was employed for friction and wear evaluation of a palm oil-commercial grade oil (PO-CGO) blend, which consisted of various weight fractions of functionalized multiwall carbon nanotubes (FMWCNTs) to lubricate steel-steel contacts of ball specimens mounted in tribometer. The specimens were lubricated by using 0.1 wt.% FMWCNT blended PO-CGO oil showed about 38% and 35% reduction in wear scar diameter and wear volume respectively compared to CGO lubricated test samples. Furthermore, roughness values of specimens obtained from atomic focal microscope (AFM) by using 0.1 wt.% nanomaterial blended lubricant showed about 88% lower values than that of CGO lubricated specimens. Raman spectroscopy and SEM/EDS results revealed the details of tribofilm formation and corresponding chemical composition on sliding contact surfaces of ball specimens subjected to PO-CGO and FMWCNT-blended oil lubrication. [ABSTRACT FROM AUTHOR]

Thermal management of the new generation's high performance electronic and mechanical devices is becoming important due to their miniaturization. Conventionally, the plate fin arrangement is widely used for removal of dissipated heat but, their effectiveness is not up to mark. Among different options, the most attractive and efficient alternative for overcoming this problem is micro pin fin heat sink. This paper presents the experimental investigation of square micro-pin fins heat sink for identifying the most suitable pin fin geometry for heat removal applications under forced convection. Twenty five square micro pin fin heat sinks were tested for three different heat load and Reynolds number. The results show that for large fin height lower thermal resistance was observed at the cost of large pressure drop. The dimensionless heat transfer coefficient increases with fin height and Reynolds number while it decreases with increasing fin spacing. The improvement in micro pin fin efficiency were observed by about 2 to 9% owing to presence of fins on the impingement surface, flow mixing, disruption of the boundary layers, and augmentation of turbulent transport. [ABSTRACT FROM AUTHOR]

The objective of this article is to examine the influence of different weight percentages (wt%) of graphene nanoplatelets (GNPs) on the behavior of mechanical and abrasive wear. Furthermore, the influence of operating parameters, such as, different degrees of applied loads and abrading distance (5‐20 N and 100‐250 m, respectively) at a rotational speed of 200 rpm (1.047 m/s) against SiC paper of 400 grit size was studied. From the present study, it was possible to establish that performance of the glass fabric‐reinforced epoxy composite materials can be improved with incorporation of GNPs. Moreover, incorporation of a large amount (1 wt%) of GNPs was found to noticeably enhance the tribo‐performance, ILSS, and hardness of the composite materials. However, the tensile strength was noted to increase negligibly with incorporation of 1 wt% of GNPs as compared to 0.5 wt% of GNPs. To get an insight into the wear mechanisms, the abraded surface of the tribological samples was examined by scanning electronic microscopy and energy dispersive X‐ray. Their morphology was correlated with wear volume and specific wear rate data trends. Worn surface features analysis indicated that incorporation of GNPs mainly improved the fiber‐matrix interface, which resists easy pullout of fibers from matrix/fillers and enables higher wear resistance. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Mn, and Cu based ternary metal oxide nano adsorbents are studied for arsenic remediation. • XPS of As(3d), Fe(2p), Cu(2p), Mn(2p), and O(1s) is performed to understand remediation mechanism. • As(0) (∼25–78 at.%) onto the adsorbent shows environmentally responsible behavior to address arsenic leaching issue. • Trace metal voltammetry inferred a better As(III) mitigation (∼75–90 % at C i ∼ 1 ppm). • Cyclic voltammetry (CV) confirmed arsenic mitigation, and immobilization by reduction, and sorption. Abstract Arsenic mitigation behavior in aqueous systems is being evaluated for Mn-Al-Fe, Cu-Al-Fe nano adsorbents. Morphological, and vibrational spectroscopy analysis are observed with As-OH, and As-O surface complexes. XPS study of individual As(3d) spectra at different parameters is observed with multiplet peak behavior attributed to redox behavior of Mn-Al-Fe, Cu-Al-Fe. Significant proportions of As(0) signal (∼25 at.% in pH 7, ∼78 at.% in pH 2, ∼58 at.% in pH 12) implicate an environmentally stable behavior of these adsorbents to address the arsenic leaching issue. Adsorption kinetics are observed with Pseudo Second Order (PSO) model, and Freundlich model supported multilayer adsorption behavior is observed for adsorption isotherms. Trace metal voltammetry studies are observed with 75–90 % of As(III) mitigation in aliquot samples. Detailed study of Mn(2p), Cu(2p), Fe(2p), and O(1 s) spectra explains redox active, and surface ligand exchange synergism in arsenic adsorption. Low equilibrium concentrations (C e < 10 ppb) in As(V) systems (C i ∼ 100 and 500 ppb) indicate the drinking water application of these systems. Cyclic-voltammetry (CV) studies implicate the mitigation and immobilization of arsenic species onto adsorbent by both reduction, and sorption phenomenon. [ABSTRACT FROM AUTHOR]

Abstract Conventional Cr as a protective coating on gun barrels is electro-deposited from toxic hexavalent chromium electrolyte, which can be susceptible to cracking and tends to spall off. Herein, environment friendly trivalent Cr bath was utilized to electrodeposit chromium based composite coatings on armour steel with the incorporation of 3 mol% yttria stabilised zirconia (3YSZ) and carbon nano tubes (CNT). Higher dislocation density (17 × 1015 m−2), yield strength (4.6 GPa), calculated using Taylor's model, and reduced plasticity index (0.29) resulted in an enhanced hardness (∼25 GPa) and elastic modulus (∼206 GPa) for the synergistically incorporated YSZ and CNT in Cr matrix when compared to the Cr, Cr-YSZ and Cr-CNT coatings (using micro and nano-indentation techniques). Moreover, the fretting wear testing also elicited Cr-YSZ-CNT as most adroit coating having enhanced wear resistance (wear rate ∼3.7 × 10−5 mm3/Nm) due to the efficient presence of compressive stress (−918 MPa) and fine crystallite size (11 nm). The reduction in Hertzian contact diameter, from 32 μm for Cr to 27 μm for Cr-YSZ-CNT coating, results in a decreased tribological interaction between the counter body and coating material during the wear test. The mechanism involved in Cr-YSZ-CNT coating, grafted significantly with the mechanical and tribological performance, was attributed to toughening by YSZ nanoparticles that strengthen Cr matrix and impart higher resistance to crack-propagation during fretting wear. While the lubrication and bridging phenomenon of CNTs can potentially seal-up the initiation and propagation of cracks and pores within the matrix, thereby reducing the damage due to the wear. Thus, the dexterous mechanical and tribological performance of Cr-YSZ-CNT coating over Cr, Cr-YSZ and Cr-CNT coatings, makes it suitable composite material for gun barrel protection. Highlights • Electro-deposition of Cr coatings from trivalent Cr bath. • Reinforcement of Cr with YSZ, CNT and YSZ+CNT. • Enhanced hardness and elastic modulus from nano and micro-indentation in Cr-YSZ-CNT. • High wear resistance (wear rate ∼3.7 × 10−5 mm3/Nm) from fretting in Cr-YSZ-CNT. • High compressive stress (−918 MPa) exist in Cr-YSZ-CNT coating which restricts wear. [ABSTRACT FROM AUTHOR]

In CNC milling, the feed rate scheduling is a frequently used method to increase machining quality and efficiency. Among the benefits of feed rate scheduling, this paper focuses on controlling the tool load and optimizing the machining time. Although the advantages of feed rate scheduling are undeniable, some areas remain still to be addressed. In order to control the tool load, geometric methods are often used, which are based on keeping a specific parameter, such as chip thickness or material removal rate (MRR) constant. However, a high level of tool load control can only be provided if cutting force models or experimental-based techniques are used. Besides traditional methods, this paper presents an artificial neural network (ANN)-based feed rate scheduling method to keep the tool load constant, using data gained by preliminary cutting experiments. A case study demonstrates that a significantly higher level of tool load control can be achieved with this method as compared to the geometric models. Besides controlling the tool load, the present feed rate scheduling method also addresses the consideration of acceleration limits which is of great importance for practical uses. The application of feed rate scheduling in trochoidal milling is also discussed in detail in this paper. This area has not received enough attention, as due to the limited fluctuation of cutter engagement, the tool load was considered as well-controlled. However, experiments have shown that in the case of trochoidal milling, the introduction of feed rate scheduling can still further increase the machining efficiency. Using the developed ANN-based feed rate scheduling method, significant progress could be made as compared to conventional technologies in controlling the cutting force and optimizing the machining time. In the present case study, a reduction of 50% in machining time was achievable by adjusting the feed rate without increasing the peak value of cutting force. [ABSTRACT FROM AUTHOR]

In recent years, trochoidal milling has become greatly widespread since it provides high productivity and long tool life, especially when cutting difficult-to-machine materials. Numerous studies have dealt with the analytical description and the experimental investigation of the evolution of cutting force, temperature, tool wear, chatter stability, etc. However, most of these analyses are focusing on the conventional circular and cycloid-shape trajectories. Only a few studies address the potential of improving the efficiency by modifying the tool path shape, leaving significant reserves untapped. If the mathematical formulation of the trajectory cannot be described easily, then a sophisticated optimisation algorithm is needed to determine the appropriate tool path shape. To overcome these difficulties at trochoidal milling of straight slots, the present work proposes a new tool path generation algorithm that can maximize the average material removal rate (MRR) while controlling the tool load. In this approach, the tool path is modelled by a B-spline curve whose control points are optimised using a differential evolution algorithm. The developed tool path generation strategy was compared through simulations and experiments with two widely used solutions viz the traditional cycloid-shaped tool path and a modern approach used in computer-aided manufacturing (CAM) systems. The results reveal that the developed method is able to control the tool load and the smoothness of the tool path, and most importantly, also exceeds the existing methods in terms of productivity. [ABSTRACT FROM AUTHOR]

Active and durable oxygen reduction reaction (ORR) catalysts are of utmost importance to realize the commercialization of hydrogen fuel cells and metal-air batteries. Al-substituted MnFe 2 O 4 -based ternary oxide and reduced graphene oxide (MAF-RGO) nanocomposite is synthesized using an in-situ co-precipitation followed by a hydrothermal process and verified for ORR electrocatalysis in the alkaline electrolyte (0.1 M KOH). MAF-RGO is first analyzed using physicochemical characterization tools including X-ray diffraction, Raman spectroscopy, sorption studies, electron microscopy, X-ray photoelectron spectroscopy, etc. Further, the characteristic ORR peak centered at 0.56 V vs. reversible hydrogen electrode (RHE) in cyclic voltammetry (CV) studies confirms the electrocatalytic performance of MAF-RGO. The ORR onset potential of 0.92 V vs. RHE is obtained in linear sweep voltammetry (LSV) measurement at 1600 rpm in O 2 -saturated electrolyte exhibiting an improved ORR performance as compared to the commercial electrocatalyst. The reduction kinetics is observed to follow the desirable near 4-e- mechanism. In addition, the electrocatalyst exhibits improved relative current stability of 86% and methanol poisoning resistance of 82%, which is better in comparison to the standard Pt/C. The observed electrochemical performance results from the synergism between the oxygen vacancy-rich Al-substituted metallic oxide active species and the functional group enriched predominantly mesoporous RGO sheets with excellent electrical conductivity. The introduction of metallic species enhanced the inter-planar spacing between graphitic sheets easing the maneuver of reactant species through the electrocatalyst and accessing more ORR-active sites. This study establishes the potency of mixed transition metal oxide/nanocarbon composites as durable high-performance ORR-active systems. [Display omitted] • Excellent current durability and poisoning stability are obtained in alkaline medium. • Al-substituted metal oxide and RGO act in synergy to improve the ORR performance. • Effect of Al-induced O-vacancies in MAF-RGO hybrid on the ORR activity is explored. [ABSTRACT FROM AUTHOR]

[Display omitted] • Deterministic cellular lattice structures of IN718 are fabricated through LPBF. • Through-holes EDM drilling is performed on LPBF-fabricated lattice structures. • Machined holes show dimensional variability due to pores, nodes, and lattice defects. • Near-circular through-holes machined by optimizing EDM parameters and electrode positioning. Additive manufactured (AM) metallic lattice structures are being largely explored for different engineering applications. The fastening, implantation, and installation of such lattice structures demand secondary processing. In the current work, through-hole drilling is performed using electrical discharge machining (EDM) on Inconel 718 (IN718) lattice structures fabricated by laser powder bed fusion (LPBF). The challenges in EDM hole drilling have been encountered and uncertainty in the machined holes owing to periodically open pores and nodes in the lattice structures sizes has been identified. Finally, an experimental strategy has been proposed for near-circular hole drilling by design optimization and tool positioning with respect to the cellular structures. [ABSTRACT FROM AUTHOR]

In the present work, electrodeposited chromium coatings were strengthened with 3 mol% yttria-stabilised zirconia nanoparticles (YSZ) and carbon nanotubes (CNT) to analyse anti-corrosive and wear properties of the coatings. Highest hardness (~24 GPa), minimum scratch wear rate i.e. ~3 × 10−11 m3/Nm and highest corrosion resistance of ~3.9 kΩcm2 was obtained by synergistic incorporation of YSZ and CNT in Cr matrix. This can be linked to high dislocation density ~22 × 1011 cm−2 (Orowan effect) and compressive residual stresses i.e. ~840 MPa (Cr-YSZ-CNT), which tend to seal-up micro-holes and cavities, thereby, restricting the onset of wear and corrosion in the matrix. Addition of inert YSZ nanoparticles imparts chemical stability as well as hardness to the Cr matrix (~11 GPa for Cr-YSZ, ~8.4 GPa for Cr). Further, CNT incorporation, apart from matrix strengthening, results in low COF (~0.12) due to self-lubricating nature of CNTs, which leads to reduced wear rate of ~3.8 × 10−11 m3/Nm (Cr-CNT) with respect to Cr and Cr-YSZ. Thus, barrier protection and corrosion inhibition might be protective mechanisms for Cr-YSZ-CNT coating that make it suitable for engineering and industrial applications in order to protect the vital components exposed to tribological and corrosive media conditions. • Scratch and electrochemical behavior of Cr based electrochemical composite coatings • Cr-coating reinforced with yttria stabilized zirconia (YSZ), & carbon nanotube (CNT). • High compressive residual stresses in the range ~264-840 MPa in composite coatings. • Restricted wear rate (~3×10-11 m3/Nm) from micro-scratch in Cr-YSZ-CNT. • High corrosion resistance of ~3.9 kΩcm2 in Cr-YSZ-CNT coatings. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The first derivative of XANES for As(III) adsorbed systems of all adsorbents are observed to have with mixed oxidation. • As(V) adsorbed samples of Ni, and Cu systems agree with that of As(V) standards. • Both reduction and oxidation behavior of arsenic is observed on to these metal oxide adsorbents. • EXAFS analysis was observed with As O bond distances in the range of 1.7–1.8 Å. • The As-M bond distances are around 2.7, 3.2 and 3.6 Å confirmed the formation of surface complexes. Abstract The present study is about surface complexation behavior of arsenic species adsorbed onto ternary metal oxide adsorbents (Ni-Al-Fe, Co-Al-Fe, Mn-Al-Fe, and Cu-Al-Fe). The analysis is carried out by X-ray absorption spectroscopy (XAS) tool. XANES (μ(E) vs. E) spectra close to the absorption edge (i.e., As K -edge) of all samples are observed along with the As(III) and As(V) standards. The first derivative of XANES for Ni-As(V), and Cu-As(V) samples agree with that of As(V) standards, respectively. Whereas, As(III) adsorbed adsorbent systems (i.e., Ni, Co, Mn, and Cu) are observed with mixed oxidation state of arsenic. A total of 65–85 % is observed with initial oxidation state (As(III) or As(V)), and remaining 15–35 % is observed with modified oxidation state (As(V) or As(III)) that explains the occurrence of possible charge transfer. EXAFS analysis shows the As-O bond distances in the range of 1.7–1.8 Å. The corresponding As-M bond distances are around 2.7, 3.2, and 3.6 Å which confirms the formation various edge sharing (2E), and corner sharing (2C, 1V) surface complexes. Surface coverage is understood as an important parameter as bidentate attachments (2E, 2C) are evident in As(III), and As(V), but monodentate attachments (1V) are only observed in As(V). [ABSTRACT FROM AUTHOR]

• Laser shock peening on armored steel using air, water and silicone oil attenuation medium. • Enhanced wear damage tolerance of laser peened armored steel under water attenuation. • High compressive residual stresses of ∼150–319 MPa obtained on the laser peened armored steel. • Minimum wear rate of ∼2.61 × 10-8 mm3/N.m observed in laser peened armor steel at 450 mJ. In the present study, the effect of Laser Shock Peening (LSP) on wear characteristics of armor steel is investigated to mitigate the material degradation in tank barrels and prolong their service life. Tank barrels are exposed to enormous temperatures and pressures during rapid firing rounds, which invoke the material's failure and calls for a barrel replacement and the reinvestment of millions of dollars. LSP performed at different pulse energies (i.e., 450 mJ, 350 mJ, and 250 mJ) with varying attenuating media such as air, water, and silicone oil, have resulted in high wear resistance and superior mechanical properties compared to that of armor steel. Water attenuation with a pulse energy of 450 mJ has resulted in surface hardness of ∼495 ± 3 H V , compressive residual stresses of ∼319 ± 2 MPa, and exhibited minimum wear rate of ∼2.61 × 10-8 ± 0.04 × 10-8 mm3/N.m, capable of limiting wear and erosion problems, thereby enhancing the service life of tank barrels. [ABSTRACT FROM AUTHOR]

Excimer laser at 248 nm has been used to micromachine holes and channels on stainless steel and polymethyl methacrylate using mask projection methods. The machining is numerically simulated considering the laser beam as a heat source only, thermal diffusion, and melt vaporization. The depth and width of the machined features at different pulse energies and number of pulses are measured by optical profilometry. Both the depth and the aspect ratio (depth-to-width) are found to increase with increasing number of pulses and pulse energies. The depth predicted by the simulations based on the thermal ablation model is closer to the experimental observations for steel as compared with that for the polymer. This allows for the quantification of the contribution of thermal ablation processes in the excimer laser machining of metals and polymers. High-energy pulses are found to have higher ablation efficiency in case of metal and lower ablation efficiency in case of polymer. [ABSTRACT FROM AUTHOR]

The understanding of mechanistic insights in environmental remediation and mitigation systems is attracting larger attention, in recent days. Here in, aluminium substituted copper ferrite impregnated rGO hybrid (CAF-rGO) is verified to understand the adsorption/electrosorption mechanism of arsenic in aqueous systems. Near-surface study (XPS: As 3d, Cu 2p, Fe 2p, Al 2p, O 1s, C 1s) proposes redox, and ligand exchange reactions between contaminant, and CAF-rGO. Adsorption capacities are observed around 128.8 mg g−1 [As(III)], 153.5 mg g−1 [As(V)] with Freundlich model isotherms. Kinetics study follows the PSO model with influence of solar light (> 420 nm). Cyclic voltammetry (CV) analysis in different molarity conditions observed with signals around +0.1 and −0.6 V confirm the redox abilities, and N 2 /O 2 purged environments understood that electrosorption occurred through both reduction and sorption. Electrosorption study with pH variation shows the effect of protonation on the redox activity of individual arsenic species. Consistent signal around −0.6 ± 0.05 V in all the CV plots (i.e., Molarity, Environment, pH) recommends the usage of CAF-rGO for arsenic mitigation. Possible influence of photo-current (∼40 μA/cm2 at ∼ 0 V) towards As(III/V) decontamination is understood though photoelectrochemical analysis. Impedance plot shows low-resistance and better diffusion of arsenic oxy-anions during light irradiation. Synergistic nature of CAF-rGO generates reactive oxygen species (i.e., ●OH/●O 2 −/ 1 O2) in mitigating highly toxic As(III) species is also detailed in the present work. Image 1 • Mechanistic insights of arsenic (As) adsorption and electrosorption in aqueous systems. • In-situ CV analysis in various molarities, gas purging environment and pH conditions. • A constructive correlation is drawn between individual redox signals and CV plot areas. • Photo-catalytic aspects on As loading and photo-electrochemical behavior (I vs. t, EIS). • ROS signals onto the hybrid surface in influencing As remediation and mitigation. [ABSTRACT FROM AUTHOR]

Aluminum (Al3+) doped manganese (Mn)/copper (Cu) ferrite impregnated rGO hybrids are verified for photo-electrocatalytic water-splitting and super-capacitor electrode applications. Energy band gaps of 2.17 eV (Mn) and 2.25 eV (Cu) confirm photocatalytic activity in the visible-band. High anodic photo-currents around 18–40 and 2–9 mA/cm2 (1 V vs. Ag/AgCl) are observed for Mn and Cu systems. Formation of oxygen vacancies due to aluminum doping assisted in efficient charge transfer behavior both at surface and lattice orders due to the structural adjustments. 2-D rGO surface disorders (I D /I 2D) emphasized the retardation of the charge recombination at the metal-oxide and rGO junction. During visible-light irradiation current densities are increased by 0.7–9.2 mA/cm2 with a better redox behavior. The difference in transient currents are observed around 0.01–0.02 mA/cm2 at 0 V vs. Ag/AgCl [0.7 mA/cm2 at 0.5 V]. Intrinsic photo-current at zero voltage infers built-in potentials at the hybrid and electrolyte interface (Schottky- junction). Impedance study implicates better electron-transfer/ion diffusion characteristics during photon irradiation with a semi-infinite diffusion rate-limiting step. Specific-capacities (Three-electrode) are observed around 216 F g−1 (Mn), 142 F g−1 (Cu) with combined pseudo-capacitance and EDLC characteristics. Li+-intercalation results in ultrahigh stability up to 100,000 cycles (t ~ 69.4 h) at 0.8 V s−1 with a capacity retention of 127%. Two-Electrode performance shows 99.1% capacity retention after 5000 cycles with decrease in the impedance (1.38 Ω to 1.06 Ω), and a maximum areal energy density of 0.54 μWh cm−2 at power density of 50 μW cm−2. Image 1 [ABSTRACT FROM AUTHOR]

• MAF-rGO hybrid is verified for better arsenic (As) remediation under visible light (λ > 420 nm). • Photo-catalytic/electrocatalytic synergised MAF-rGO: High photocurrent density (0.9 mA cm−2). • XPS analysis confirmed the occurrence of redox reactions and ligand exchange phenomenon. • CV studies provide the mechanism of electro-sorption through reduction and sorption. • Sustainable use of sludge as ultra-high stable supercapacitor electrode (~100,000 cycles). Synergistic Mn-Al-Fe impregnated rGO hybrid (MAF-rGO) is developed and verified for arsenic remediation. Preliminary adsorption studies are observed through vibrational spectroscopy and morphological tools. Adsorption isotherms are fitted by Freundlich model multilayer sorption with a loading of 402 mg g−1 [As(III)], and 339 mg g−1 [As(V)]. Adsorption kinetics study in competing ion environment [SO 4 2−, PO 4 3−, NO 3 −, CO 3 2−] confirms the PSO model-controlled chemisorption as the rate-limiting step. The irradiation of white light (> 420 nm) in adsorption kinetics study shows a two-fold increase in the arsenic loading parameters (5–10 min). Multiplet peaks in As3d spectra (XPS) confirm the transformation of arsenic species in the near-surface region of hybrid [i.e., As(III), As(V)]. The occurrence of redox-active, ligand-exchange reactions are confirmed by individual Mn2p, Fe2p, Al2p, O1s, and C1s spectra. The dedicated electrochemical study confirms arsenic decontamination occurred through both reduction and sorption (i.e., electrosorption). An energy bandgap (E g) of 2.17 eV resulted in the photocatalytic activity, which enhanced the arsenic remediation. Photo-electrocatalytic synergism resulted in high photocurrent densities (0.2–0.9 mA cm−2) with charge separation [e−–h+], and built-in potential abilities (Schottky-junction; Water-splitting). Arsenic-treated hybrid (i.e., sludge) is observed with an ultra-high stable charge–discharge cyclic performance for 100,000 cycles (~77 %) with improved specific-capacity of 125 F g−1 over pristine hybrid (92 F g−1). The better electrochemical parameters of sludge are due to the efficient lithiation/de-lithiation process supported by adsorbed arsenic. This work proposes sustainable approach towards environmental remediation and energy storage applications. [ABSTRACT FROM AUTHOR]

In electrochemical micromachining (ECMM), improved material dissolution localization and generation of the smooth machined surface under pulsed voltage condition is attributed to the fact that short pulse-duration time results in the generation of relatively less volume of dissolution products. The intermittent supply of voltage provides idle time to flush the hydrogen bubbles and sludge from the machining zone and, also increases control over the dissolution process. From the last few decades, various studies have been carried out to analyze the effect of short pulse voltage to ultra-short pulsed (rectangular) voltage. Development of such a sophisticated system capable of supplying ultra-high frequency voltage pulses is challenging, cost in-effective and complex. Also, the compromising ways of reducing the pulse energy by reducing the duty cycle and increasing the pulse frequency impose increased voltage requirement and idle time while machining. In this study, an approach of reducing pulse energy per unit time by changing the waveform of the voltage pulse (while keeping the pulse-duration time the same) for reducing the overcut is presented. A theoretical model is developed first to quantify the input energy per pulse for rectangular, sinusoidal, and triangular voltage pulses. This ensured that by changing the shape of voltage pulses of same on-time, the energy input per pulse can be further altered. A function generator based pulsed power supply is then developed with the capability of generating rectified voltage pulses of different waveforms. The process of ECMM for generating micro dimples on a flat surface is modeled in two dimensions using finite element method in MATLAB (R2018b). Three numerical models for sinusoidal, rectangular and triangular voltage pulses are developed for predicting the current density and anode shape. Simulation results demonstrated that triangular voltage pulse yields minimum diameter of micro-dimple as compared to sinusoidal and rectangular pulse respectively. Results from the developed model are also validated using experimental observations and a good correlation between the two was observed (with an average deviation of 18%). Image 1 • Theoretical and numerical model considering sinusoidal, rectangular and triangular voltage pulses are developed. • A function generator based pulsed power supply and machining setup are developed for experimental validation. • Micro-dimples are fabricated for determining the reduction in diameter in dimples with reducing the pulse energy. • Experimental comparison of effect of pulse energy by increasing frequency and pulse shape deformation is established. [ABSTRACT FROM AUTHOR]