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31.
Surface modified ormosil nanoparticles 总被引:1,自引:0,他引:1
Organically modified silanes (ORMOSIL) such as vinyl triethoxysilane readily aggregate in the aqueous cores of reverse micelles where the triethoxysilane moieties are hydrolyzed to form a hydrated silica network and the vinyl groups protruded out from the surface of the nanoparticles toward the hydrophobic side of the micellar interface. These particles are spherical and the size distribution of the particles is relatively narrow, with an average diameter of 87 nm. Surface vinyl silica nanoparticles so formed have been oxidized to surface carboxylic silica nanoparticles, followed by chemical conjugation with polyethyleneglycol amine (PEG amine) through the ethyl-3-(3-dimethylaminopropyl) (EDCI) carbodiimide reaction. The characteristic surface groups have been identified by Fourier transform infrared spectroscopy, while the size and the morphology of the particles have been studied by dynamic light scattering and transmission electron microscopy. It has been found that about 80-85% of the carboxylic groups are PEGylated during the EDCI reaction. 相似文献
32.
As a polycation with diverse applications in biomedical and environmental engineering, polyethylenimine (PEI) can be synthesized with varying degrees of branching, polymerization, and can exist in different protonation states. There have been some interests in molecular modeling of PEI at all-atom or coarse-grained (CG) levels, but present CG models are limited to linear PEIs. Here we present the methodology to systematically categorize bond lengths, bond angles and dihedral angles, which allows us to model branched PEIs. The CG model was developed under the Martini scheme based on eight ~600 Da PEIs, with four different degree of branching at two different protonation states. Comparison of the CG model with all-atom simulations shows good agreement for both local (distributions for bonded interactions) and global (end-to-end distance, radius of gyration) properties, with and without salt. Compatibility of the PEI model with other CG bio-molecules developed under the Martini scheme will allow for large-scale simulations of many PEI-enabled processes. © 2018 Wiley Periodicals, Inc. 相似文献
33.
Akbar Hossain Milan Skalicky Marian Brestic Sagar Maitra Sukamal Sarkar Zahoor Ahmad Hindu Vemuri Sourav Garai Mousumi Mondal Rajan Bhatt Pardeep Kumar Pradipta Banerjee Saikat Saha Tofazzal Islam Alison M. Laing 《Molecules (Basel, Switzerland)》2021,26(4)
The trace element selenium (Se) is a crucial element for many living organisms, including soil microorganisms, plants and animals, including humans. Generally, in Nature Se is taken up in the living cells of microorganisms, plants, animals and humans in several inorganic forms such as selenate, selenite, elemental Se and selenide. These forms are converted to organic forms by biological process, mostly as the two selenoamino acids selenocysteine (SeCys) and selenomethionine (SeMet). The biological systems of plants, animals and humans can fix these amino acids into Se-containing proteins by a modest replacement of methionine with SeMet. While the form SeCys is usually present in the active site of enzymes, which is essential for catalytic activity. Within human cells, organic forms of Se are significant for the accurate functioning of the immune and reproductive systems, the thyroid and the brain, and to enzyme activity within cells. Humans ingest Se through plant and animal foods rich in the element. The concentration of Se in foodstuffs depends on the presence of available forms of Se in soils and its uptake and accumulation by plants and herbivorous animals. Therefore, improving the availability of Se to plants is, therefore, a potential pathway to overcoming human Se deficiencies. Among these prospective pathways, the Se-biofortification of plants has already been established as a pioneering approach for producing Se-enriched agricultural products. To achieve this desirable aim of Se-biofortification, molecular breeding and genetic engineering in combination with novel agronomic and edaphic management approaches should be combined. This current review summarizes the roles, responses, prospects and mechanisms of Se in human nutrition. It also elaborates how biofortification is a plausible approach to resolving Se-deficiency in humans and other animals. 相似文献
34.
35.
Chayan Patra Valay Agarawal Dipanjali Halder Anish Chakraborty Dibyendu Mondal Sonaldeep Halder Rahul Maitra 《Chemphyschem》2023,24(4):e202200633
The coupled cluster iteration scheme for determining the cluster amplitudes involves a set of nonlinearly coupled difference equations. In the space spanned by the amplitudes, the set of equations are analyzed as a multivariate time-discrete map where the concept of time appears in an implicit manner. With the observation that the cluster amplitudes have difference in their relaxation timescales with respect to the distributions of their magnitudes, the coupled cluster iteration dynamics are considered as a synergistic motion of coexisting slow and fast relaxing modes, manifesting a dynamical hierarchical structure. With the identification of the highly damped auxiliary amplitudes, their time variation can be neglected compared to the principal amplitudes which take much longer time to reach the fixed points. We analytically establish the adiabatic approximation where each of these auxiliary amplitudes are expressed as unique parametric functions of the collective principal amplitudes, allowing us to study the optimization with the latter taken as the independent degrees of freedom. Such decoupling of the amplitudes significantly reduces the computational scaling without sacrificing the accuracy in the ground state energy as demonstrated by a number of challenging molecular applications. A road-map to treat higher order post-adiabatic effects is also discussed. 相似文献
36.
A series of deoxycholic and cholic acid‐derived oligomers were synthesized and their ability to extract hydrophilic dye molecules of different structure, size, and functional groups into nonpolar media was studied. The structure of the dye and “dendritic effect” in the extraction process was examined using absorption spectroscopy and dynamic light scattering (DLS). The efficiency of structurally preorganized oligomers in the aggregation process was evaluated by 1‐anilinonaphthalene‐8‐sulfonic acid (ANS) fluorescence studies. The possible formation of globular structures for higher‐generation molecules was investigated by molecular modeling studies and the results were correlated with the anomaly observed in the extraction process with this molecule. The ability of these molecules for selective extraction of specific dyes from blended colors is also reported. 相似文献
37.
U. K. Yadav T. Maitra I. Singh 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,84(3):365-370
Thermodynamic properties of the spinless Falicov-Kimball model are studied on a
triangular lattice using numerical diagonalization technique with Monte-Carlo simulation
algorithm. Discontinuous metal-insulator transition is observed at finite temperature.
Unlike the case of square lattice, here we observe that the finite temperature effect is
not able to smear out the discontinuous metal-insulator transition seen in the ground
state. Calculation of specific heat (C
v
)
shows single and double peak structures for different values of parameters like on-site
correlation strength (U), f-electron energy
(E
f
) and temperature. 相似文献
38.
Chemically synthesized "pro-sensitizers" release the sensitizer in the presence of lipase or β-glucosidase, triggering a significant luminescence response from a lanthanide based hydrogel. 相似文献
39.
The sharp depletion of attenuation of 22.235 GHz signal before the onset of Nor’wester over Kolkata, India is observed and
possible explanation of such type of variation is presented. It is concluded that this may be taken as one possible method
of forecasting severe thunderstorm associated with Nor’wester. Physical explanations based on the formation and dissipation
mechanisms of thunderstorm are also presented. 相似文献
40.