Search results for "Function"
showing 10 items of 14432 documents
Solute retention in reversed-phase chromatography as a function of stationary phase properties: Effect of n-alkyl chain length and ligand density
1988
Two series of bonded phases were synthesized employing LiChrospher Si 100, 10 μm and n-alkyldimethylmonochlorosilanes as silanizing reagents. In series A the n-alkyl chain length, n, of the bonded phase was varied between 1 and 20 at a constant ligand density of 3.5±0.2μmol·m−2. In series B the ligand density, d, was gradually changed from 0 to 4.1μmol·m−2 on the C1, C4, C6, C8 and C18 bonded phases, respectively.
Asialofetuin Liposomes for Receptor-Mediated Gene Transfer into Hepatic Cells
2003
Publisher Summary The liver is an excellent organ for gene transfer in treating a wide variety of diseases that affect liver function. It is an ideal organ for a high amount of expression of therapeutic genes and efficient systemic distribution of the resulting therapeutic proteins secreted into the bloodstream. For strategies of liver-destined gene therapy, the liver sinusoid endothelium contains pores with a mean diameter of 100 nm, which allow small vectors to leave the blood circulation and reach the hepatocytes. The preparation of asialofetuin–liposomes targeted to hepatocytes can be made by covalent coupling of asialofetuin glycoprotein (ASF) onto the liposome surface, by the use of h…
Butene Isomerization and Double-Bond Migration on the H-ZSM-5 Outer Surface: A Density Functional Theory Study
2011
Isomerization of trans-but-2-ene to cis-but-2-ene and double bond migration of trans-but-2-ene to but-1-ene have been investigated by means of density functional theory calculations on a suitable model of H-ZSM-5 surface. The study has been afforded on outer surface sites by considering the hydroxyl group of either a SiO2(OH)2 or a AlO2H(OH)2 moiety. On these outer surface sites, one alkoxide species occurs as a stable intermediate both along the isomerization and double bond migration pathways. The latter process could also occur via a single-step mechanism, which involves a six-center transition state. The energy barriers of the outer surface processes above do not take any advantage by t…
Phase Separation and Nematic Order in Lyotropic Solutions: Two Types of Polymers with Different Stiffnesses in a Common Solvent
2021
The interplay of the isotropic-nematic transition and phase separation in lyotropic solutions of two types of semiflexible macromolecules with pronounced difference in chain stiffness is studied by Density Functional Theory and Molecular Dynamics simulations. While the width of the isotropic-nematic two-phase coexistence region is narrow for solutions with a single type of semiflexible chain, the two-phase coexistence region widens for solutions containing two types of chains with rather disparate stiffness. In the nematic phase, both types of chains contribute to the nematic order, with intermediate values of the order parameter compared to the corresponding single component solutions. As …
The Role of Planarity versus Nonplanarity in the Electronic Communication of TCAQ-Based Push–Pull Chromophores
2018
Donor-acceptor-substituted alkynes, endowed with 11,11,12,12-tetracyano-9,10-anthraquinodimethane (TCAQ) and N,N-dimethylaniline (DMA) units, have been further functionalized by a [2+2] cycloaddition with tetracyanoethylene (TCNE) followed by a subsequent retro-electrocyclization to form distorted nonplanar structures with bridging 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) units. Comprehensive spectroscopic, electrochemical, and computational studies have been carried out to compare the electronic communication in planar (alkyne bridges) and nonplanar (TCBD bridges) TCAQ-based push-pull chromophores. Cyclic voltammetry and UV/Vis absorption measurements confirm the electronic communication be…
Structure and dynamics of dibutylphosphate/n-propylamine ionic liquid: A multi-scale theoretical study
2021
Abstract Owing to the amphiphilic nature of their constituent molecules, binary mixtures of pure liquid surfactants are usually characterized by enhanced nano-segregation and thus can exhibit interesting transport properties and complex macroscopic behavior. In this ambit it was recently shown by Turco Liveri et al. (2018) that mixtures of short aliphatic chains compounds at room temperature, such as dibutyl phosphate (DBP) and n-propylamine (PA) liquids, display ionic liquid–like behavior ascribed to phosphate-to-amine proton transfer. To gain a detailed molecular picture of the system structure and dynamics and to understand the molecular mechanisms at the basis of the observed behavior, …
Interaction of 5‐fluorouracil with β‐cyclodextrin: A density functional theory study with dispersion correction
2020
Detailed studies on the stability, interaction, and microstructure of host‐guest complexes in the vacuum of 5‐fluorouracil (5FU) with β‐cyclodextrin (βCD) were performed using B3LYP with the inclusion of Grimme's dispersion correction GD3 term and 6‐31+G(d,p) basis set. Among several studied 1:1 5FU‐βCD complexes, the one placing the keto tautomer of 5FU vertically in the host cavity and forming N‐H···OCD and CO···HOCD hydrogen bonds with hydroxyl groups of the smaller rim of βCD has the highest stability (Eint = −195 kJ/mol). Interestingly, there are no interactions with the inner hydrophobic part of the βCD host cavity. The strength of the intermolecular H‐bonds to the smaller rim of βC…
Dynamics of weak interactions in the ligand layer of meta-mercaptobenzoic acid protected gold nanoclusters Au68(m-MBA)32 and Au144(m-MBA)40
2020
Atomically precise metal nanoclusters, stabilized and functionalized by organic ligands, are emerging nanomaterials with potential applications in plasmonics, nano-electronics, bio-imaging, nanocatalysis, and as therapeutic agents or drug carriers in nanomedicine. The ligand layer has an important role in modifying the physico-chemical properties of the clusters and in defining the interactions between the clusters and the environment. While this role is well recognized from a great deal of experimental studies, there is very little theoretical information on dynamical processes within the layer itself. Here, we have performed extensive molecular dynamics simulations, with forces calculated…
Functional Liquid Crystalline Polymers: Ferroelectric Polymers and Liquid Crystalline Elastomers and Ionomers
1994
Abstract The incorporation of different functional groups in liquid crystalline polymers opens the way to a variety of interesting new materials, which may be used for non-linear optics, as piezo-elements or as two-phasic composite materials.
Engineered Multifunctional Nanotools for Biological Applications
2011
Smart multifunctional magnetic nanoparticles are popular candidates for several biological applications owing to their intrinsic magnetic property and diverse applications that range from rare protein separation and biomedical utilization to cancer therapy and diagnostics. A universal protocol, for the development of such nanocarriers, is highly desirable for scientists with different backgrounds so that custom-made multifunctional nanoparticles can be developed to address their needs, among which are the superparamagnetic iron oxide and manganese oxide nanoparticles that are synthesized through high temperature decomposition reactions. However, an interface is needed to present these inorg…