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JETP Letters - The magnetic properties of Co-doped CdS has been investigated by ab initio calculations using the GGA + U approximation. The study reveals the ferromagnetic ordering of Co-doped CdS... 相似文献
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Das Pritam Kumar Mallik Arnab Kumar Molla Altaf Hossain Santra Apurba Kumar Ganguly Ranjan Saha Abhijit Kumar Sugam Aswal V. K. 《Journal of Thermal Analysis and Calorimetry》2022,147(10):5617-5635
Journal of Thermal Analysis and Calorimetry - Nanofluids have gained recent attention because of their potential applications in diverse engineering fields like enhancing thermal transport,... 相似文献
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Sugam Kharel Kyle J. Cluff Nattamai Bhuvanesh John A. Gladysz Janet Blümel 《化学:亚洲杂志》2019,14(15):2704-2711
The three secondary phosphine oxides [CH2=CH(CH2)4]2HPO ( 1 ), [CH2=CH(CH2)5]2HPO ( 2 ), and [CH2=CH(CH2)6]2HPO ( 3 ), and two diphosphine dioxides, {[CH2=CH(CH2)6]2PO(CH2)7}2 ( 4 ) and {[CH2=CH(CH2)6]2PO(CH2)4}2 ( 5 ), incorporating long methylene chains, are described. The single crystal X‐ray structures of 1 , 2 , and 5 have been determined. The phosphine oxides 3 , 4 , and 5 have been adsorbed on silica in submonolayer quantities to give 3 a – 5 a . The 1H, 13C, and 31P solid‐state NMR spectra of polycrystalline 3 – 5 have been analyzed and compared with those of 3 a – 5 a . The changes of the solid‐state NMR characteristics upon adsorption and the surface mobilities of the phosphine oxides are discussed. 相似文献
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Rahul Rama Hegde Sugam Kumar Vinod K. Aswal Anurag Verma Shiv Sankar Bhattacharya Amitava Ghosh 《Journal of Dispersion Science and Technology》2014,35(6):783-788
The structure of micelles formed by a four component water-in-oil nonionic microemulsion surfactant polyoxyethene (20) sorbitan monoleate (Tween 80), sorbitan monolaurate (Span 20) at ethyl oleate and deuterated water interface have been probed by small-angle neutron scattering (SANS). The total surfactant concentration in each of the samples studied (Tween 80: Span 20) is fixed at 3:2. The deuterated water content is variable at 5–60% w/w. The experimental SANS data from all the seven samples are fit well by spherical micelles interacting with hard sphere potential. Increased deuterated water leads to spherical to lamellar and rod-like micelle geometry featured in the SANS scattering data. The observed change in micelle geometry supports the characterization of phase transition between the self-assembled micelles of the nonionic microemulsion. 相似文献
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Kumar S Aswal VK Kohlbrecher J 《Langmuir : the ACS journal of surfaces and colloids》2011,27(16):10167-10173
The interaction of lysozyme protein (M.W. 14.7 kD) with two sizes of silica nanoparticles (16 and 25 nm) has been examined in aqueous solution using UV-vis spectroscopy and small-angle neutron scattering (SANS). The measurements were performed on fixed concentration (1 wt %) of nanoparticles and varying concentration of protein in the range 0 to 2 wt %. The adsorption isotherm as obtained using UV-vis spectroscopy suggests strong interaction of the two components and shows an exponential behavior. The saturation values of adsorption are found to be around 90 and 270 protein molecules per particle for 16 and 25 nm sized nanoparticles, respectively. The adsorption of protein on nanoparticles leads to the aggregation of particles and these structures have been studied by SANS. The aggregates are characterized by fractal structure coexisting with unaggregated particles at low protein concentrations and free proteins at higher protein concentrations. Further, contrast variation SANS measurements have been carried out to differentiate the adsorbed and free protein in these systems. 相似文献
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Structures and Unexpected Dynamic Properties of Phosphine Oxides Adsorbed on Silica Surfaces 下载免费PDF全文
Dr. Casie R. Hilliard Sugam Kharel Kyle J. Cluff Dr. Nattamai Bhuvanesh Prof. John A. Gladysz Prof. Janet Blümel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(52):17292-17295
Solid‐state NMR spectroscopy of selected phosphine oxides adsorbed on silica surfaces establishes the surface mobilities, even of phosphine oxides with high melting points. Crystal structures of the adducts Ph3PO ? HOSiPh3 and Cy3PO ? H2O indicate that the interactions with silica involve hydrogen bonding of the P?O group to adsorbed water and surface silanol groups. 相似文献
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Kumar S Aswal VK Kohlbrecher J 《Langmuir : the ACS journal of surfaces and colloids》2012,28(25):9288-9297
The size-dependent interaction of anionic silica nanoparticles with ionic (anionic and cationic) and nonionic surfactants has been studied using small-angle neutron scattering (SANS). The surfactants used are anionic sodium dodecyl sulfate (SDS), cationic dodecyltrimethyl ammonium bromide (DTAB), and nonionic decaoxyethylene n-dodecylether (C(12)E(10)). The measurements have been carried out for three different sizes of silica nanoparticles (8, 16, and 26 nm) at fixed concentrations (1 wt % each) of nanoparticles and surfactants. It is found that irrespective of the size of the nanoparticles there is no significant interaction evolved between like-charged nanoparticles and the SDS micelles leading to any structural changes. However, the strong attraction of oppositely charged DTAB micelles with silica nanoparticles results in the aggregation of nanoparticles. The number of micelles mediating the nanoparticle aggregation increases with the size of the nanoparticle. The aggregates are characterized by fractal structure where the fractal dimension is found to be constant (D ≈ 2.3) independent of the size of the nanoparticles and consistent with diffusion-limited-aggregation-type fractal morphology in these systems. In the case of nonionic surfactant C(12)E(10), micelles interact with the individual silica nanoparticles. The number of adsorbed micelles per nanoparticle increases drastically whereas the percentage of adsorbed micelles on nanoparticles decreases with the increase in the size of the nanoparticles. 相似文献
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Rajwinder?Kaur Sugam?Kumar Vinod?K.?Aswal Rakesh?Kumar?MahajanEmail author 《Colloid and polymer science》2012,290(2):127-139
The aqueous mixed systems of twin tail cationic surfactants didodecyldimethylammonium bromide, ditetradecyldimethylammonium
bromide, and dihexadecyldimethylammonium bromide with pluronic L64 have been studied to determine the bulk aggregation and
interactional behavior. Various experimental techniques, namely small-angle neutron scattering (SANS), fluorescence, conductivity,
and surface tension, have been employed to investigate the mixed micellization. The SANS data analysis has been employed to
determine the shapes of different aggregates formed. Pure twin tail cationic surfactants form vesicles whereas the micelles
of pure pluronic L64 are spherical. The mixed systems (surfactant + L64) also form spherical micelles, and the spherical shape
of mixed micelles is predominantly controlled by pluronic L64. Various interfacial parameters such as surface excess (Γ
max), minimum area per molecule (A
min), and thermodynamic parameters such as the standard Gibbs free energy of micellization (DGmic0 \Delta G_{{mic}}^{{0}} ), Gibbs free energy of adsorption (DGads0 \Delta G_{{ads}}^{{0}} ), and effective Gibbs free energy (DGeff0 \Delta G_{{eff}}^{{0}} ) have been determined from the surface tension measurements. The results were interpreted on the basis of pseudophase separation
model and regular solution theory. The interactions of each surfactant with pluronic L64 are found to be nonideal and antagonistic.
The repulsive nature of the interaction is explained on the basis of the changes in the microenvironment of micelles of pluronic
L64. Micelles of pluronic L64 are less hydrophobic and contains significant amount of water, and inclusion of hydrophobic
alkyl chains of twin tail cationic surfactants disturbs this microenvironment of pluronic L64 micelle. 相似文献
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