Atomistic simulations to study crack tip behaviour in single crystal of bcc niobium and hcp zirconium

In this article, molecular dynamics based simulations were carried out to study the fracture toughness of single crystals of niobium (Nb) and zirconium (Zr). Separate set of simulations were performed with different orientations of crack plane in Nb and Zr. In each case, efforts were made to align the crack front with principal planes of corresponding crystal structure, that was bcc for Nb and hcp for Zr. Deformation in single crystal of Nb and Zr was governed either by twinning or emergence of dislocations from the crack tip and surfaces. The deformation mechanism in single crystal of Nb and Zr also helps in governing the overall toughness of the material, while deforming via twinning leads to higher change in the crack length, whereas dislocations emerging from the crack tip blunts the opening and improves the toughness.     

Anomalous Stretching Dynamics of Tagged Monomer of Branched Polymer in Layered Random Flows

Journal of Statistical Physics - We extend our formalism to theoretically understand the stretch dynamics of single tagged monomer of flexible branched polymer with arbitrary topology in the...     

Molecular Dynamic Simulation Search for Possible Amphiphilic Drug Discovery for Covid-19

To determine whether quaternary ammonium (k21) binds to Severe Acute Respiratory Syndrome–Coronavirus 2 (SARS-CoV-2) spike protein via computational molecular docking simulations, the crystal structure of the SARS-CoV-2 spike receptor-binding domain complexed with ACE-2 (PDB ID: 6LZG) was downloaded from RCSB PD and prepared using Schrodinger 2019-4. The entry of SARS-CoV-2 inside humans is through lung tissues with a pH of 7.38–7.42. A two-dimensional structure of k-21 was drawn using the 2D-sketcher of Maestro 12.2 and trimmed of C18 alkyl chains from all four arms with the assumption that the core moiety k-21 was without C18. The immunogenic potential of k21/QA was conducted using the C-ImmSim server for a position-specific scoring matrix analyzing the human host immune system response. Therapeutic probability was shown using prediction models with negative and positive control drugs. Negative scores show that the binding of a quaternary ammonium compound with the spike protein’s binding site is favorable. The drug molecule has a large Root Mean Square Deviation fluctuation due to the less complex geometry of the drug molecule, which is suggestive of a profound impact on the regular geometry of a viral protein. There is high concentration of Immunoglobulin M/Immunoglobulin G, which is concomitant of virus reduction. The proposed drug formulation based on quaternary ammonium to characterize affinity to the SARS-CoV-2 spike protein using simulation and computational immunological methods has shown promising findings.     

Impact Assessment of Electroplating in the Leaching of Harmful Metals from Utensils

Electroplating is a widely used technique in the manufacturing of utensils for household and commercial use. This process involves the deposition of a metal coating onto a base material, such as steel or brass, to improve the aesthetics, durability, and corrosion resistance of the utensil. Several studies have investigated the migration of heavy metals from utensils, but there is a lack of research specifically focused on the impact of electroplating on this phenomenon. Therefore, this research article aims to assess the impact of electroplating by analyzing the migration of heavy metals from such utensils. The objective of this research is to assess the impact of electroplating on the migration of heavy metals from utensils. The research also aims to evaluate the impact of coating thickness. Stainless-steel and brass utensils (Plate, Tumbler, and Bowl) are purchased. The samples are analyzed as per standard test methods based on inductively coupled plasma mass spectrometry (ICP-MS) techniques. Leaching stimulant is used for extraction process. Testing is performed in an ISO/IEC 17025: 2017 accredited laboratory. The experiments reveal that the electroplating process decreased the migration of lead from the utensils. These findings highlight the need for stricter regulations and standards to ensure the safety of electroplated utensils.     

Fabrication of visible light driven nano structured Copper,Boron codoped TiO2 for photocatalytic removal of Lissamine Green B

In the present research work a potentially improved Copper (Cu) and Boron (B) codoped TiO₂ nano materials were synthesized by varying the different dopant concentrations (Copper 0.25, 0.50, 0.75, 1?wt% and Boron 0.25, 0.50, 0.75, 1?wt%) using solgel method for the photocatalytic degradation of Lissamine Green B. In order to investigate the physical, chemical and optical properties of a catalyst, which play a key role in its photocatalytic activity, as prepared samples were characterized by various instrumental techniques. The crystalline phase study performed for all the samples using X-ray powder diffraction (XRD) confirmed the formation of anatase TiO₂. Chemical composition of the prepared catalyst investigated by X-ray photo electron spectroscopy (XPS) affirmed the presence of constituent elements (Ti, O, Cu & B) on the catalyst surface. The surface microstructure studied by field emission scanning electron microscopy (FE-SEM) revealed that the TiO₂ particles having spherical shape with rough surface morphology. The average particle size and surface area of the catalyst determined by high-resolution transmission electron microscopy (HRTEM) and Brunauer-Emmett-Teller (BET) surface area analyser, revealed that the codoped catalyst shows a high percentage of small particles of size 6.8?nm and a high surface area of 135.6?m²/g, respectively. The band edge absorption shift of the samples was determined by diffuse reflectance spectroscopy analysis (DRS) and the results exhibited that among all the codoped samples Copper 0.25?wt% and Boron 1?wt% (CBT1) catalyst shows a reduced band gap energy of 2.73?eV. The characterization results supported the photocatalytic activity of the catalyst for the degradation of Lissamine Green B within 90?min at the optimum reaction parameters such as dopant concentration of Cu at 0.25?wt% & B at 1?wt%, pH?=?3, catalyst dosage 0.075?g/L and dye concentration 10?mg/L under visible light irradiation. The mechanism of enhanced photocatalytic performance of the catalyst was proposed by the results obtained from the PL spectra and main reactive species trapping measurements.     

Chain Folding Controlled by an Isomeric Repeat Unit: Helix Formation versus Random Aggregation in Acetylene‐Bridged Carbazole–Bipyridine Co‐Oligomers

An unprecedented, positional effect of the isomeric repeat unit on chain folding in donor–acceptor‐linked oligomers, which contain alternating bipyridine and carbazole moieties that are connected through an acetylinic linkage, is reported. 4,4′‐Linked oligomer 1 adopts an intrachain helical conformation (CD‐active) in CHCl₃/MeCN (20:80 v/v), whereas oligomer 2 , which contains an isomeric 6,6′‐linkage, forms interchain randomly coiled aggregates (CD‐inactive). The substitution position plays a significant role in controlling the variations in electronic effects and dipole moments around the bipyridyl moiety, which are responsible for this observed phenomenon. Two model compounds of oligomers 1 and 2 ( 3 and 4 , respectively) were prepared and their properties were compared. A systematic investigation of the photophysical and CD properties of these structures, as well as theoretical studies, support our conclusions.     

Bioleaching of Fly Ash by the Tropical Marine Yeast, Yarrowia lipolytica NCIM 3589

Fly ash collected from an Indian thermal power plant was characterised by scanning electron microscope (SEM)-energy dispersive spectrometer, X-ray diffraction and energy dispersive X-ray fluorescence analysis. The effect of fly ash on the growth and morphology of a metal-tolerant tropical marine yeast, Yarrowia lipolytica NCIM 3589, was studied. The growth of the yeast was unaffected by the presence 0.1, 0.2 or 0.3?% fly ash although the surface-to-volume ratio decreased. The yeast formed biofilms on immobilized fly ash as evidenced by SEM observations. The organism produced citric acid and additional extracellular proteins in the presence of fly ash. Leaching of metals from fly ash by Y. lipolytica was compared with chemical leaching by citric acid. Yeast cells were most effective in leaching Cu (59.41?%) although other metals (Zn, Ni, Cu and Cr) were also extracted. Transmission electron microscope images showed the deposition of metals at the cell wall, cell membrane and in the cytoplasm. This paper thus reports a potential application of Y. lipolytica for removal of different metals from solid waste material (fly ash).     

Orientational Order Parameter in 1-Hexyl-4-(4-Isothiocyanatophenyl) Bicyclo [2,2,2] Octane using X-Rays

Abstract

1-Hexy1-4-(4-isothiocyanatophenyl)bicyclo[2,2,2]octane (HIPBO), a nematic liquid crystal which shows nematic phase in the temperature range 52.8 to 90.2°C, has been used along with imaging plate system to record X-ray Laue type diffraction pattern at different temperatures. For this purpose oriented sample was used. Orientational order parameter was obtained using Fourier method, recently reported by us, and has been compared with that of other existing methods.     

Catalytic asymmetric heterodimerization of ketenes

In this Communication we describe an unprecedented catalytic asymmetric heterodimerization of ketenes of wide substrate scope. The alkaloid-catalyzed method provides access to ketene heterodimer β-lactones and allows even two different monosubstituted ketenes to be cross-dimerized, with excellent enantioselectivity (17 examples with ≥90% ee) and excellent heterodimer regioselectivity observed in all cases.     

A facile synthetic strategy for mesoporous crystalline copper–polyaniline composite

A facile and novel strategy for preparing mesoporous crystalline copper–polyaniline composite is reported wherein the reaction is carried out at room temperature using copper nitrate as the oxidizing agent and methanol as the solvent. The composite obtained as a precipitate has been characterized using UV–visible absorption spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption–desorption method, Barrett–Joyner–Halenda (BJH) method, Brunauer–Emmett–Teller method (BET) and thermogravimetric analysis (TGA). The XRD studies in conjunction with the BJH method reveals that the composite has crystalline nature with a mesoporous structure and has a diameter of 3.5 nm. The specific surface area of copper–polyaniline composite is estimated to be as high as 63.2 m² g^?1 using the BET surface area plot. The characterization of the filtrate indicates the presence of pernigraniline with a very small weight percent of copper.