Indo Korea Science and Technology

Abstract The d-band center model of Hammer and Nørskov is widely used in understanding and predicting catalytic activity on transition metal (TM) surfaces. Here, we demonstrate that this model is inadequate for capturing the complete catalytic activity of the magnetically polarized TM surfaces and propose its generalization. We validate the generalized model through comparison of adsorption energies of the NH 3 molecule on the surfaces of 3d TMs (V, Cr, Mn, Fe, Co, Ni, Cu and Zn) determined with spin-polarized density functional theory (DFT)-based methods with the predictions of our model. Compared to the conventional d-band model, where the nature of the metal-adsorbate interaction is entirely determined through the energy and the occupation of the d-band center, we emphasize that for the surfaces with high spin polarization, the metal-adsorbate system can be stabilized through a competition of the spin-dependent metal-adsorbate interactions.

Abstract Introduction This survey of international experts in obesity management was conducted to achieve consensus on standardized definitions and to identify areas of consensus and non-consensus in metabolic bariatric surgery (MBS) to assist in an algorithm of clinical practice guidelines for the management of obesity. Methods A three-round Delphi survey with 136 statements was conducted by 43 experts in obesity management comprising 26 bariatric surgeons, 4 endoscopists, 8 endocrinologists, 2 nutritionists, 2 counsellors, an internist, and a pediatrician spanning six continents over a 2-day meeting in Hamburg, Germany. To reduce bias, voting was unanimous, and the statements were neither favorable nor unfavorable to the issue voted or evenly balanced between favorable and unfavorable. Consensus was defined as ≥ 70% inter-voter agreement. Results Consensus was reached on all 15 essential definitional and reporting statements, including initial suboptimal clinical response, baseline weight, recurrent weight gain, conversion, and revision surgery. Consensus was reached on 95/121 statements on the type of surgical procedures favoring Roux-en-Y gastric bypass, sleeve gastrectomy, and endoscopic sleeve gastroplasty. Moderate consensus was reached for sleeve gastrectomy single-anastomosis duodenoileostomy and none on the role of intra-gastric balloons. Consensus was reached for MBS in patients > 65 and < 18 years old, with a BMI > 50 kg/m 2 , and with various obesity-related complications such as type 2 diabetes, liver, and kidney disease. Conclusions In this survey of 43 multi-disciplinary experts, consensus was reached on standardized definitions and reporting standards applicable to the whole medical community. An algorithm for treating patients with obesity was explored utilizing a thoughtful multimodal approach. Graphical Abstract

Ligands can control the surface chemistry, physicochemical properties, processing, and applications of nanomaterials. MXenes are the fastest growing family of two-dimensional (2D) nanomaterials, showing promise for energy, electronic, and environmental applications. However, complex oxidation states, surface terminal groups, and interaction with the environment have hindered the development of organic ligands suitable for MXenes. Here, we demonstrate a simple, fast, scalable, and universally applicable ligand chemistry for MXenes using alkylated 3,4-dihydroxy-l-phenylalanine (ADOPA). Due to the strong hydrogen-bonding and π-electron interactions between the catechol head and surface terminal groups of MXenes and the presence of a hydrophobic fluorinated alkyl tail compatible with organic solvents, the ADOPA ligands functionalize MXene surfaces under mild reaction conditions without sacrificing their properties. Stable colloidal solutions and highly concentrated liquid crystals of various MXenes, including Ti2CTx, Nb2CTx, V2CTx, Mo2CTx, Ti3C2Tx, Ti3CNTx, Mo2TiC2Tx, Mo2Ti2C3Tx, and Ti4N3Tx, have been produced in various organic solvents. Such products offer excellent electrical conductivity, improved oxidation stability, and excellent processability, enabling applications in flexible electrodes and electromagnetic interference shielding.

In Pt-transition metal (TM) alloy catalysts, the electron transfer from the TM to Pt is retarded owing to the inevitable oxidation of the TM surface by oxygen. In addition, acidic electrolytes such as those employed in fuel cells accelerate the dissolution of the surface TM oxide, which leads to catalyst degradation. Herein, we propose a novel synthesis strategy that selectively modifies the electronic structure of surface Co atoms with N-containing polymers, resulting in highly active and durable PtCo nanoparticle catalysts useful for the oxygen reduction reaction (ORR). The polymer, which is functionalized on carbon black, selectively interacts with the Co precursor, resulting in Co–N bond formation on the PtCo nanoparticle surface. Electron transfer from Co to Pt in the PtCo nanoparticles modified by the polymer is enhanced by the increase in the difference in electronegativity between Pt and Co compared with that in bare PtCo nanoparticles with the TM surface oxides. In addition, the dissolution of Co and Pt is prevented by the selective passivation of surface Co atoms and the decrease in the O-binding energy of surface Pt atoms. As a result, the catalytic activity and durability of PtCo nanoparticles for the ORR are significantly improved by the electronic ensemble effects. The proposed organic/inorganic hybrid concept will provide new insights into the tuning of nanomaterials consisting of heterogeneous metallic elements for various electrochemical and chemical applications. Attaching bimetallic nanoparticles to a special, polymer-modified support improves the durability and activity of fuel-cell catalysts. Nanoscale alloys consisting of platinum and transition metals such as cobalt or iron have emerged as promising catalysts for fuel-cell cathodes because they can reduce costs and accelerate the oxygen reduction reaction through electron-transfer processes. Sung Jong Yoo and co-workers from Korea and India have developed a catalyst support that prevents surface oxides from attacking platinum-cobalt (PtCo) alloys and degrading their performance. The team reacted a typical carbon-black support with poly(N-isopropylacrylamide), a polymer possessing nitrogen atoms that bind to cobalt without physically blocking access to platinum catalytic sites. The hybrid organic-inorganic catalyst reduces premature alloy dissolution during fuel-cell operation and enhances electron transfer from Co to Pt atoms. Amide group-containing polymer functionalized on carbon surfaces selectively interacts with the Co precursor, resulting in Co–N bond formation on PtCo nanoparticle surfaces. The electron transfer from Co to Pt is enhanced due to increased electronegativity difference between Pt and Co. In addition, the dissolution of Co and Pt during the oxygen reduction reaction (ORR) is retarded by the selective passivation of surface Co atoms and the decrease in the O-binding energy of surface Pt atoms. As a result, the catalytic activity and durability of the hybrid PtCo nanoparticles for the ORR are significantly improved by the electronic ensemble effects.

Finding an "ideal" catalyst is a matter of great interest in the communities of chemists and material scientists, partly because of its wide spectrum of industrial applications. Information regarding a physical parameter termed "adsorption energy", which dictates the degrees of adhesion of an adsorbate on a substrate, is a primary requirement in selecting the catalyst for catalytic reactions. Both experiments and in silico modeling are extensively being used in estimating the adsorption energies, both of which are an Edisonian approach, demand plenty of resources, and are time-consuming. In this paper, employing a data-mining approach, we predict the adsorption energies of monoatomic and diatomic gases on the surfaces of many transition metals (TMs) in no time. With less than a set of 10 simple atomic features, our predictions of the adsorption energies are within a root-mean-squared error (RMSE) of 0.4 eV with the quantum many-body perturbation theory estimates, a computationally expensive method with a good experimental agreement. Based on the important features obtained from machine learning models, we construct a set of mathematical equations using the compressed sensing technique to calculate adsorption energy. We also show that the RMSE can be further minimized up to 0.10 eV using the precomputed adsorption energies obtained with the conventional exchange and correlation (XC) functional by a new set of scaling relations.

A-site cation doping in perovskite-based materials (ABO₃ formula) has a significant effect on the bifunctional oxygen activity of the electrocatalysts with chemical stability, enabling the design of highly active, durable, and cost-effective catalysts.

BaTiO3(BTO) ceramics were prepared by a sol-gel auto combustion method. Barium nitrate and Titanyl nitrate used as starting precursors and citric acid used as a chelating agent. BaTiO3 ceramics were synthesized at calcination temperature of 900°C for 2h and sintered at 1100°C for 1h. The crystalline Tetragonal phase was confirmed by X-ray diffraction results. The Williamson–Hall (W–H) method and size–strain method to evaluate the size of crystallites and strain in the BaTiO3 ceramics' peak broadening were applied. Physical parameters such as strain values were calculated for all XRD reflection peaks corresponding to the Tetragonal phase of BaTiO3 in the range of 20–80°C from the W–H plot and by the size–strain plot (SSP) method. The calculated crystallite size of developed BaTiO3 Nanoparticles by scherrer method, modified scherrer method, Williamson-Hall plot and size strain plot comes out to be 56.4nm, 62.4 nm, 72.7 nm, 62.1 nm respectively. The crystal size of the BaTiO3 ceramics calculated on the SSP method are in good agreement with the modified scherrer and Scherrer method.

Binders play a pivotal role in the process of electrode fabrication, ensuring the cohesion and stability of active materials, conductive additives, and electrolytes within battery systems. They play a critical part in establishing essential pathways for both electrons and ions, fundamental to efficacious lithiation and delithiation processes. Despite their relatively minor presence in terms of concentration compared to active materials, binders exert significant influence on the physical characteristics and electrochemical performance of electrodes. With the increasing demand for electric vehicles and energy storage systems, the necessity for batteries with heightened energy densities and economically viable production methods has escalated. This necessitates the development of more efficient binder materials. This comprehensive review delves into the multifaceted realm of binders utilized in battery production, commencing with traditional polymer binders. It critically examines their limitations in high-temperature and conductivity-demanding environments, necessitating the exploration of inorganic binders. However, these inorganic binders often lack adhesion capabilities compared to polymer binders. The review further delves into the realm of hybrid binders, strategically amalgamating the benefits of polymeric and inorganic binders. Moreover, it evaluates the concept of multifunctional binders, which also contribute to the electrode interface, conductivity, and high stability and provide self-healing properties to the electrode along with binding properties. Additionally, the review addresses recent advancements in binder technology, particularly in the context of sodium-ion batteries, silicon anodes, lithium–oxygen batteries, and other emerging energy storage technologies. The systematic exploration of diverse binder types and their distinctive attributes contributes significantly to the optimization and progression of battery technologies. As the energy storage landscape continues its dynamic evolution, the insights presented herein serve as a valuable foundation for innovative binder design and application, catalyzing advancements in the field. Importantly, the review concludes by shedding light on the flourishing use of machine learning methodologies in the development of emerging binder technologies, amplifying the trajectory of battery innovation.

Finding the active center in a bimetallic zeolite imidazolate framework (ZIF) is highly crucial for the electrocatalytic oxygen evolution reaction (OER). In the present study, we constructed a bimetallic ZIF system with cobalt and manganese metal ions and subjected it to an electrospinning technique for feasible fiber formation. The obtained nanofibers delivered a lower overpotential value of 302 mV at a benchmarking current density of 10 mA cm–2 in an electrocatalytic OER study under alkaline conditions. The obtained Tafel slope and charge-transfer resistance values were 125 mV dec–1 and 4 Ω, respectively. The kinetics of the reaction is mainly attributed from the ratio of metals (Co and Mn) present in the catalyst. Jahn–Teller distortion reveals that the electrocatalytic active center on the Mn-incorporated ZIF-67 nanofibers (Mn-ZIF-67-NFs) was found to be Mn3+ along with the Mn2+ and Co2+ ions on the octahedral and tetrahedral sites, respectively, where Co2+ ions tend to suppress the distortion, which is well supported by density functional theory analysis, molecular orbital study, and magnetic studies.

An $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ framework for combined atomistic spin and lattice dynamics is introduced. The new approach comprises the descriptions of the damped driven oscillator for the ionic displacements as well as the spin dynamics according to Landau-Lifshitz-Gilbert theory. Both schemes are recovered in the limit of small spin-lattice coupling.

${\mathrm{Co}}_{2}$-based Heusler compounds are promising materials for spintronics applications due to their high Curie temperature, large spin polarization, large magnetization density, and exotic transport properties. In the present paper, we report the anomalous Hall effect (AHE) in a polycrystalline ${\mathrm{Co}}_{2}\mathrm{FeAl}$ Heusler compound using combined experimental and theoretical studies. The Rietveld analysis of high-resolution synchrotron x-ray diffraction data reveals a large degree $(\ensuremath{\sim}50%)$ of antisite disorder between Fe and Al atoms. The analysis of anomalous transport data provides the experimental anomalous Hall conductivity (AHC) about 227 S/cm at 2 K with an intrinsic contribution of 155 S/cm, which has nearly constant variation with temperature. The detailed scaling analysis of anomalous Hall resistivity suggests that the AHE in ${\mathrm{Co}}_{2}\mathrm{FeAl}$ is governed by the Berry phase driven intrinsic mechanism. Our theoretical calculations reveal that the disorder present in the ${\mathrm{Co}}_{2}\mathrm{FeAl}$ compound enhances the Berry curvature induced intrinsic AHC.

Spinel NiFe 2 O 4 -NFs and Pd–NiFe 2 O 4 -NFs were synthesised via an electrospinning (ES) method and the designed materials show excellent OER and HER activity, respectively. In full-cell studies, it requires a minimum cell voltage of 1.51 V @ 10 mA cm −2 .

Synopsis of a long-duration video has many applications in intelligent transportation systems. It can help to monitor traffic with lesser manpower. However, generating meaningful synopsis of a long-duration video recording can be challenging. Often summarized outputs include redundant contents or activities that may not be helpful to the observer. Moving object trajectories are possible sources of information that can be used to generate the synopsis of long-duration videos. The synopsis generation faces challenges due to object tracking, grouping of the trajectories with respect to activity type, object category, and contextual information, and generating smooth synopsis according to a query. In this paper, we propose a method to generate meaningful and smooth synopsis of long-duration videos according to the users' query. We have tracked moving objects and adopted deep learning to classify the objects into known categories (e.g., car, bike, and pedestrians). We then identify regions in the surveillance scene with the help of unsupervised clustering. Each tube (spatiotemporal object trajectory) is represented by the source and the destination. In the final stage, we take a query from the user and generate the synopsis video by smoothly blending the appropriate tubes over the background frame through energy minimization. The proposed method has been evaluated on two publicly available datasets and our own surveillance datasets. We have compared the method with popular state-of-the-art techniques. The experiments reveal that the proposed method is superior to the existing techniques and it produces visually seamless video synopsis.

BACKGROUND AND AIM: Endoscopic sleeve gastroplasty (ESG) is gaining acceptance as a non-surgical option for the treatment of obesity. However, its role is still not consolidated for all populations and the ideal indications are yet to be determined. We aimed to study the efficacy and safety of ESG in Indian patients. METHODS: We conducted a single-center retrospective study of obese patients who underwent consecutive ESG at our tertiary care center. Data on weight loss and adverse events at 1, 3, 6, and 12 months were collected and analyzed. RESULTS: , respectively. Mean duration of procedure was 68.96 ± 11.19 min. Immediate postoperative complications included mainly epigastric pain (45.2%) and nausea (22.6%) but there was no serious adverse event. Average percentage of total weight loss (%TWL) was 8.26%, 11.96%, 14.25%, and 19.94% at 1, 3, 6, and 12 months, respectively. Eighty-eight percent of patients achieved >15% TWL at 12 months. Younger patients (<30 years old) and female patients had greater %TWL at 12 months (P = 0.01 and P = 0.021, respectively). Last 18 procedures were significantly faster than the first 35 cases (P = 0.01). CONCLUSIONS: Endoscopic sleeve gastroplasty is effective and safe at promoting weight loss in the Indian population. Young age and female gender are related to better outcomes.

Formation of galvanic cells between constituent phases is largely responsible for corrosion in Mg-based alloys. We develop a methodology to calculate the electrochemical potentials of intermetallic compounds and alloys using a simple model based on the Born-Haber cycle. Calculated electrochemical potentials are used to predict and control the formation of galvanic cells and minimize corrosion. We demonstrate the applicability of our model by minimizing galvanic corrosion in Mg-3wt%Sr-xZn alloy by tailoring the Zn composition. The methodology proposed in this work is applicable for any general alloy system and will facilitate efficient design of corrosion resistant alloys.

BaTiO3 (BTO) typically demonstrates a strong n-type character with absorption only in the ultraviolet (λ ≤ 390 nm) region. Extending the applications of BTO to a range of fields necessitates a thorough insight into how to tune its carrier concentration and extend the optical response. Despite significant progress, simultaneously inducing visible-light absorption with a controlled carrier concentration via doping remains challenging. In this work, a p-type BTO with visible-light (λ ≤ 600 nm) absorption is realized via iridium (Ir) doping. Detailed analysis using advanced spectroscopy/microscopy tools revealed mechanistic insights into the n- to p-type transition. The computational electronic structure analysis further corroborated this observation. This complementary data helped establish a correlation between the occupancy and the position of the dopant in the band gap with the carrier concentration. A decrease in the Ti3+ donor-level concentration and the mutually correlated oxygen vacancies upon Ir doping is attributed to the p-type behavior. Due to the formation of Ir3+/Ir4+ in-gap energy levels within the forbidden region, the optical transition can be elicited from or to such levels, resulting in visible-light absorption. This newly developed Ir-doped BTO is a promising semiconductor with imminent applications in solar fuel generation and optoelectronics.

Abstract MXenes are a promising class of two‐dimensional transition metal carbides, nitrides, and carbonitrides, widely utilized in diverse fields such as energy storage, electromagnetic shielding, electrocatalysis, and sensing applications. Their potential in chemical sensing is particularly noteworthy, where optimizing surface chemistry for strong interaction with target analytes and increasing surface area for efficient gas adsorption are crucial factors. In this study, a versatile and general self‐assembly method for fabricating nanometer‐scale thin films of surface‐functionalized MXene, enabling high‐performance gas sensors is developed. By dropping MXene dispersed in organic solvents onto nonsolvents, rapid formation of nanometer‐scale films is achieved. This method allows easy adjustment of film properties by using different solvent‐nonsolvent combinations, leading to improved optoelectronic properties compared to conventional techniques. The surface‐functionalized MXenes using ADOPA ligands greatly enhance the gas response and long‐term environmental stability compared to pristine MXenes. Computational methods are also employed to gain insights into the molecular interactions and changes in electronic structure that contribute to the enhanced sensing properties. Furthermore, the environmental stability of MXene sensors is largely enhanced after surface functionalization, which can be attributed to increased surface hydrophobicity. Overall, this innovative technique opens up opportunities for tailoring MXene thin films for specific applications.

Spin gapless semiconductors exhibit a finite band gap for one spin channel and a closed gap for another spin channel, and they have emerged as a new state of magnetic materials with a great potential for spintronic applications. The first experimental evidence for spin gapless semiconducting behavior was observed in an inverse Heusler compound ${\mathrm{Mn}}_{2}\mathrm{CoAl}$. Here, we report a detailed investigation of the crystal structure and anomalous Hall effect in ${\mathrm{Mn}}_{2}\mathrm{CoAl}$ using experimental and theoretical studies. The analysis of the high-resolution synchrotron x-ray diffraction data shows antisite disorder between Mn and Al atoms within the inverse Heusler structure. The temperature-dependent resistivity shows semiconducting behavior and follows Mooij's criteria for disordered metal. The scaling behavior of the anomalous Hall resistivity suggests that the anomalous Hall effect in ${\mathrm{Mn}}_{2}\mathrm{CoAl}$ is primarily governed by an intrinsic mechanism due to the Berry curvature in momentum space. The experimental intrinsic anomalous Hall conductivity (AHC) is found to be $\ensuremath{\sim}35$ S/cm, which is considerably larger than the theoretically predicted value for ordered ${\mathrm{Mn}}_{2}\mathrm{CoAl}$. Our first-principles calculations conclude that the antisite disorder between Mn and Al atoms enhances the Berry curvature and hence the value of intrinsic AHC, which is in very good agreement with the experiment.

The theme of this work is to highlight the significance of green plant extracts in the synthesis of nanostructures. In asserting this statement, herein, we report our obtained results on the synthesis of hexagonal CdSe nanorods preferably oriented along (0002) plane through henna leaf extract-mediated reaction along with a discussion about the structural, morphological and optical properties of the synthesized nanorods. The possible mechanism for the synthesis of CdSe nanorods was explored. The formation of nanorods along (0002) plane was confirmed by the relatively high intensity of the (0002) peak in X-ray diffraction pattern. To account for the experimentally realistic condition, we have calculated the surface energies of hexagonal CdSe surface slabs along the low indexed (0002), <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:mn>10</mml:mn> <mml:mrow> <mml:mover> <mml:mn>1</mml:mn> <mml:mo stretchy="false">¯</mml:mo> </mml:mover> </mml:mrow> <mml:mn>0</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:mn>11</mml:mn> <mml:mrow> <mml:mover> <mml:mn>2</mml:mn> <mml:mo stretchy="false">¯</mml:mo> </mml:mover> </mml:mrow> <mml:mn>0</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:math> plane surfaces using density functional theory approach and the calculated surface energy value for (0002) surface is 802.7 mJ m −2 , which is higher than <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:mn>11</mml:mn> <mml:mrow> <mml:mover> <mml:mn>2</mml:mn> <mml:mo stretchy="false">¯</mml:mo> </mml:mover> </mml:mrow> <mml:mn>0</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:mn>10</mml:mn> <mml:mrow> <mml:mover> <mml:mn>1</mml:mn> <mml:mo stretchy="false">¯</mml:mo> </mml:mover> </mml:mrow> <mml:mn>0</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:math> surfaces. On realizing the calculated surface energies of these slabs, we determined that the combination of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:mn>11</mml:mn> <mml:mrow> <mml:mover> <mml:mn>2</mml:mn> <mml:mo stretchy="false">¯</mml:mo> </mml:mover> </mml:mrow> <mml:mn>0</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:mn>10</mml:mn> <mml:mrow> <mml:mover> <mml:mn>1</mml:mn> <mml:mo stretchy="false">¯</mml:mo> </mml:mover> </mml:mrow> <mml:mn>0</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:math> planes with lower surface energies will lead to the formation of CdSe nanorods growth along (0002) orientation. Finally, we argue that the design of new greener route for the synthesis of novel functional nanomaterials is highly desired.

The oxygen deficient site on the catalyst has a strong impact on the activation of CO2 for the synthesis of dimethyl carbonate (DMC). The Co3O4/CeO2 catalyst exhibits multiple reduction behavior as cobalt metal species differ in the strength of their interaction with CeO2. This causes the surface reduction from Ce4+ to Ce3+ in solid solution Co-O-Ce. The dispersion of Co3O4 enhanced the formation of oxygen deficient site as revealed by XPS, CO2-chemisorption and TPR. The non-precious Co3O4/CeO2 nanorod was recognized as a potential catalyst for promoting Ce4+ to Ce3+ for CO2 activation and dimethyl carbonate synthesis (81.5% of yield). Energetics of oxygen vacancy formation of low index surfaces of CeO2 was determined with first-principles calculations based on DFT. Results disclosed the Ce4+ to Ce3+ formation energy of CeO2 due to Co substitution and corroborated the experimental results. Further, calculations provide the details of the effect of Co substitution on the electronic structure of reduced CeO2 surfaces. Estimated CO2 adsorption energy indicates (110) as the most active surface for activation of CO2.