Sudripet Sharma  Prof. Jagattaran Das  Dr. Wilfried M. Braje  Dr. Ashutosh K. Dash  Prof. Sachin Handa 《ChemSusChem》2020,13(11):2806-2806

Invited for this month′s cover is the research group of Sachin Handa at the University of Louisville and Wilfried Braje at AbbVie. The image shows how green chemistry in industry and micellar catalysis are contributing toward the environmental sustainability. The Minireview itself is available at 10.1002/cssc.202000317 .  相似文献   

    

Dinesh Rathod  Saroj Kumar Dash  Arun Sarma 《等离子体物理论文集》2019,59(8)

In this work, concept of virtual cathode and its existence in dusty plasma has been studied by theoretical and numerical analysis. Using basic equations of charge dust, ions, and electrons, the non‐monotonic behaviour of the potential in presence of charged dust has been calculated and plotted as a function of dust density. It has been found that there is a change in potential between cathode and sheath potential and subsequently changes the threshold wall temperature as compared to that of without dust conditions. The threshold wall temperature has been increased due to the ability of micro‐particles acquiring electron charge and hence, reducing potential at the wall. Further, for different values of α (depends on dust density); threshold temperature remained the same for observed virtual cathode. Hence, behaviour of potential has been plotted as a function of α with increasing wall temperatures for two dust charge values (1 and 1,000). Considering no dust charge, it has been observed that, at lower dust density, double layer like structure is formed near the emissive wall. But this double layer structure gets diminishes with increasing dust density. Hence, below a threshold dust density, virtual cathode near to the emissive wall is not possible. While for Z_d = 1,000, the formation of virtual cathode appeared even at very small dust density. However, irrespective of variation of potential difference near the wall and existence of virtual cathode at different emission regime the threshold wall temperature remains same. Effect of dust potential dependency on threshold wall temperature has also been discussed in this study.  相似文献   

    

Raj Paul  Dr. Debasish Dutta  Dr. Tania Das  Dr. Manish Debnath  Prof. Dr. Jyotirmayee Dash 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(33):8590-8599

Specific sensing and functional tuning of nucleic acid secondary structures remain less explored to date. Herein, we report a thiazole polyamide TPW that binds specifically to c-KIT1 G-quadruplex (G4) with sub-micromolar affinity and ∼1 : 1 stoichiometry and represses c-KIT proto-oncogene expression. TPW shows up to 10-fold increase in fluorescence upon binding with c-KIT1 G4, but shows weak or no quantifiable binding to other G4s and ds26 DNA. TPW can increase the number of G4-specific antibody (BG4) foci and mark G4 structures in cancer cells. Cell-based assays reveal that TPW can efficiently repress c-KIT expression in leukemia cells via a G4-dependent process. Thus, the polyamide can serve as a promising probe for G-quadruplex recognition with the ability to specifically alter c-KIT oncogene expression.  相似文献   

    

Manmatha K. Roul  Sukanta K. Dash 《国际流体数值方法杂志》2011,66(11):1420-1446

Theoretical studies have been made to determine the pressure drops caused by abrupt flow area expansion/contraction in small circular pipes for two‐phase flow of air and water mixtures at room temperature and near atmospheric pressure. Two‐phase computational fluid dynamics (CFD) calculations, using Eulerian–Eulerian model (with the air phase being compressible for pipe contraction case) are employed to calculate the pressure drop across sudden expansion and contraction. The pressure drop is determined by extrapolating the computed pressure profiles upstream and downstream of the expansion/contraction. The larger and smaller tube diameters are 1.6 and 0.84 mm, respectively. Computations have been performed with single‐phase water and air, and two‐phase mixtures in a range of Reynolds number (considering all‐liquid flow) from 1000 to 12 000 and flow quality from 1.2 × 10^?3 to 1.6 × 10^?2. The numerical results are validated against experimental data from the literature and are found to be in good agreement. The expansion and contraction loss coefficients are found to be different for single‐phase flow of air and water, and they agreed reasonably well with the commonly used theoretical predictions. Based on the numerical results as well as experimental data, correlations are developed for two‐phase flow pressure drops caused by the flow area contraction as well as expansion. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

    

Swagatika Dash  Swati Mohanty 《Electrophoresis》2014,35(18):2656-2672

This paper provides an overview on separation of micron and submicron sized biological (cells, yeast, virus, bacteria, etc.) and nonbiological particles (latex, polystyrene, CNTs, metals, etc.) by dielectrophoresis (DEP), which finds wide applications in the field of medical and environmental science. Mathematical models to predict the electric field, flow profile, and concentration profiles of the particles under the influence of DEP force have also been covered in this review. In addition, advancements made primarily in the last decade, in the area of electrode design (shape and arrangement), new materials for electrode (carbon, silicon, polymers), and geometry of the microdevice, for efficient DEP separation of particles have been highlighted.  相似文献   

    

Anupam Roy  J. K. Dash  A. Rath  B. N. Dev 《Surface and interface analysis : SIA》2012,44(5):513-518

Growth of Ag islands under ultra‐high vacuum condition on air‐oxidized Si(110)‐(5 × 1) surfaces has been investigated by in situ reflection high energy electron diffraction and ex situ scanning electron microscopy and cross‐sectional transmission electron microscopy. A thin oxide is formed on Si via exposure of the clean Si(110)‐(5 × 1) surface to air. The oxide layer has a short range order. Deposition of Ag at different thicknesses and at different substrate temperatures reveal that the crystalline qualities of the Ag film are almost independent of the thickness of the Ag layer and depend only on the substrate temperature. Ag deposition at room temperature leads to the growth of randomly oriented Ag islands while preferred orientation evolves when Ag is deposited at higher temperatures. For deposition at 550 °C sharp spots in the reflection high energy electron diffraction pattern corresponding to an epitaxial orientation with the underlying Si substrate are observed. The presence of a short range order on the oxidized surface apparently influences the crystallographic orientation of the Ag islands. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

    

Milsom EV  Dash HA  Jenkins TA  Opallo M  Marken F 《Bioelectrochemistry (Amsterdam, Netherlands)》2007,70(2):221-227

Methemoglobin (bovine) is immobilized from aqueous phosphate buffer (pH 5.5) solution into thin porous TiO(2) (anatase) films at ITO electrode surfaces. Films of TiO(2) are produced in a deposition process employing 40 nm diameter TiO(2) nanoparticles suspended in dry methanol followed by calcination. The pore size in these films is sufficient for methemoglobin (ca. 6 nm diameter) to diffuse into the porous structure (over several hours) and to remain immobilized in electrochemically active form. The electrochemical reduction of methemoglobin immobilized in TiO(2) and immersed in aqueous phosphate buffer at pH 5.5 is observed in two steps with (i) a small quasi-reversible voltammetric response at -0.16 V vs. SCE (Process 1) and (ii) an irreversible reduction peak at ca. -0.5 V vs. SCE (Process 2). The irreversible response is recovered only after slow chemical re-oxidation of hemoglobin to methemoglobin. At sufficiently negative applied potential \"electrochemical doping\" of the TiO(2) host is observed to lead to a considerably enhanced reduction Process 1. TiO(2) can be temporarily switched from a non-conducting (irreversible electron transfer) into a conducting (reversible electron transfer) state.  相似文献   

    

P. Dash  D. P. Kudav  J. A. Parihar 《Journal of heterocyclic chemistry》2006,43(2):401-404

Different N‐benzyl anilines were N‐alkylated with chloroacetonitrile to give the corresponding nitriles, which were subsequently condensed with ethylenediamine in the presence of thioacetamide to afford the corresponding title antazoline derivatives.  相似文献   

    

Wang J  Dash AK  Kapon M  Berthet JC  Ephritikhine M  Eisen MS 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(23):5384-5396

The three ancillary amido moieties in the cationic complex [(Et2N)3U][BPh4] are highly reactive and are easily replaced when the complex is treated with primary amines. The reaction of [(Et2N)3U][BPh4] with excess tBuNH2 allows the formation of the cationic complex [(tBuNH2)3(tBuNH)3U][BPh4]. X-ray diffraction studies on the complex indicate that three amido and three amine ligands are arranged around the cationic metal center in a slightly distorted octahedral mer geometry. The cationic complex reacts with primary alkynes in the presence of external primary amines to primarily afford the unexpected cis dimer and, in some cases, the hydroamination products are obtained concomitantly. The formation of the cis dimer is the result of an envelope isomerization through a metal-cyclopropyl cationic complex. In the reaction of the bulkier alkyne tBuC identical to CH with the cationic uranium complex in the presence of various primary amines, the cis dimer, one trimer, and one tetramer are obtained regioselectively, as confirmed by deuterium labeling experiments. The trimer and the tetramer correspond to consecutive insertions of an alkyne molecule into the vinylic CH bond trans to the bulky tert-butyl group. The reaction of (TMS) C identical to CH with the uranium catalyst in the presence of EtNH2 followed a different course and produced the gem dimer along with the hydroamination imine as the major product. However, when other bulkier amines were used (iPrNH2 or tBuNH2) both hydroamination isomeric imines Z and E were obtained. During the catalytic reaction, the E (kinetic) isomer is transformed into the most stable Z (thermodynamic) isomer. The unique reactivity of the alkyne (TMS) C identical to CH with the secondary amine Et2NH is remarkable because it afforded the trans dimer and the corresponding hydroamination enamine. The latter probably results from the insertion of the alkyne into a secondary metal-amide bond, followed by protonolysis.  相似文献   

    

Biswaranjan Mohanty  V. K. Aswal  J. Kohlbrecher  H. B. Bohidar 《Journal of Polymer Science.Polymer Physics》2006,44(12):1653-1667

Length scale hierarchy in gelatin sol, gel, and coacervate (induced by ethanol) phases, having same concentration of gelatin in aqueous medium (13% w/v), has been investigated through small angle neutron scattering and rheology measurements. The static structure factor profile, I(q) versus wave vector q, was found to be remarkably similar for all these samples. This data could be split into three distinct q‐regimes: the low‐q regime, I_ex(q) = I_ex(0)/(1+q²ζ²)² valid for q < 3R_g^?1; the intermediate q‐regime, I(q) = I(0)/(1+q²ξ²) for 3R_g^?1 < q < ξ^?1; and the asymptotic regime, I(q) = (c/q) exp(?R_c²q²/2) for q > ξ^?1. Consequently, three distinct length scales could be deduced from structure factor data: (a) inhomogeneity of size, ζ = 20 ± 1 nm for all the three phases; (b) average mesh size, ξ₀ = 2.6 ± 0.2 nm for sol and gel, and smaller mesh size, ξ_os = 1.2 ± 0.2 nm for coacervate; and (c) cross section of gelatin chains, R_c = 0.35 ± 0.04 nm. In addition, the structure factor data obtained from coacervating solution analyzed in the Guinier region, I(q) = exp(?q²R_g²/3), yielded value of typical radius of gyration of clusters, R_g ≈ 69 nm that indicated existence of triple‐helices of length, L ≈ 239 nm; (d) Frequency and temperature sweep measurements conducted on coacervate samples revealed two other length scales: (e) viscoelastic length, ξ_ve = 14 ± 2 nm and (f) correlation length at melting, ξ_T = 500 ± 70 nm. Thus, existence of six distinct length scales, (a–f), ranging from 1.2 to 500 nm has been established in the coacervate phase of gelatin–ethanol–water system. Results are discussed within the framework of Landau‐Ginzburg treatment of dynamically asymmetric systems (Prog Theor Phys 1977, 57, 826; Phys Rev A 1991, 44, R817; J Phys II (France) 1992, 2, 1631). © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1653–1667, 2006  相似文献