A Comparative Study of Un-Modified and Modified Acrylate-SiO2 Nanocomposites

MRS Advances ◽  
2017 ◽  
Vol 2 (49) ◽  
pp. 2737-2743
Author(s):  
Mireya L. Hernández-Vargas ◽  
Rubén Castillo-Perez ◽  
Oscar Hernández-Guerrero ◽  
Bernardo F. Campillo-Illanes ◽  
Osvaldo Flores-Cedillo
Keyword(s):  
Physical Properties ◽  
Van Der Waals ◽  
Chemical Properties ◽  
Class Ii ◽  
Decomposition Temperature ◽  
Van Der Waals Interactions ◽  
Class I ◽  
Covalent Bonds ◽  
Neat Polymer ◽  
Hybrid Compounds

ABSTRACTBased on the nature of the links and interactions existing at the hybrid interface, hybrid materials can be broadly classified in two main designations: a) Hybrid compounds Class I, that include all systems with electrostatic forces, hydrogen bonding or Van der Waals interactions and b) Hybrid compounds Class II, showing that the inorganic and organic components are linked through strong covalent or ionic-covalent bonds. The physico–chemical properties of nanostructured copolymer acrylates based on butyl acrylate (BA), methyl methacrylate (MMA) and acrylic acid (AA) has been investigated employing un-modified SiO2 (Class I) and modified SiO2 particles (Class II) using 3-(trimethoxysilyl) propyl methacrylate (MPS) as compatibilizing agent. The synthesis was carried out using seeded batch emulsion polymerization system. Metastable nanostructured emulsions containing 1 wt% nanoparticles were obtained. Films casted from the in-situ nanostructured latex exhibited excellent optical transparency suggesting good nanoparticles dispersion. However, the mechanical properties showed by SiO2-MPS nanocomposite, are better than the Class I hybrid compounds. Therefore, SiO2-MPS surface treatment prior to polymerization enhances the physical properties of copolymer BA-MMA-AA film. The mass loss derivative traces for the polyacrylic nanocomposites and the neat polymer obtained by thermogravimetric analysis showed that the onset temperature for thermal decomposition was shifted towards a higher temperature than the neat polyacrylic, indicating the enhancement of thermal stability of the un-modified SiO2 nanocomposite. However, there is a decrease of 40°C in the decomposition temperature for the modified polyacrylic nanocomposite. The results obtained so far have shown that weak Van der Waals and H-bonding interactions may be sufficient to enable improvement of the physical properties of the acrylate nanocomposites.

On the Forces Between Micro and Nano Objects and a Gripper

2012 ◽  
Vol 2 (2) ◽  
pp. 15-33 ◽  
Author(s):  
Galin Valchev ◽  
Daniel Dantchev ◽  
Kostadin Kostadinov
Keyword(s):  
Liquid Phase ◽  
Physical Properties ◽  
Van Der Waals ◽  
Van Der Waals Force ◽  
Van Der Waals Interactions

The authors study the van der Waals force, between the gripper jaw and an object – cubical, spherical and conical in shape, situated at a distance L of closest approach from it. The generic and most general case is considered, when the materials of the working jaw of the gripper and the particle are made of different materials strongly preferring the liquid phase of the fluid being at temperature T and chemical potentialm. The contributions due to the standard van der Waals, as well as of the retarded (Casimir) van der Waals interactions are considered. They concluded that strongly depends on the contrast, at given fixed T and m, between the physical properties of the fluid and the material of the arms of the gripper and the particle. In addition, as expected, strongly depends on the shape of the object, its size, and the distance L between it and the working jaw of the gripper. Their approach can be applied to any nonpolar fluid.

Photo-induced Contraction of Layered Materials

MRS Advances ◽  
2018 ◽  
Vol 3 (6-7) ◽  
pp. 333-338
Author(s):  
Hiroyuki Kumazoe ◽  
Aravind Krishnamoorthy ◽  
Lindsay Bassman ◽  
Fuyuki Shimojo ◽  
Rajiv K. Kalia ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Optical Excitation ◽  
Layered Materials ◽  
Van Der Waals Interactions ◽  
Electronic Charge ◽  
Quantum Molecular Dynamics ◽  
Covalent Bonds ◽  
Coulombic Interactions ◽  
Hydrogen Bond Interactions ◽  
The Impact

ABSTRACTUltrafast atomic dynamics induced by electronic and optical excitation opens new possibilities for functionalization of two-dimensional and layered materials. Understanding the impact of perturbed valence band populations on both the strong covalent bonds and relatively weaker van der Waals interactions is important for these anisotropic systems. While the dynamics of strong covalent bonds has been explored both experimentally and theoretically, relatively fewer studies have focused on the impact of excitation on weak bonds like van der Waals and hydrogen-bond interactions. We perform non-adiabatic quantum molecular dynamics (NAQMD) simulations to study photo-induced dynamics in MoS2 bilayer. We observe photo-induced non-thermal contraction of the interlayer distance in the MoS2 bilayer within 100 femtoseconds after photoexcitation. We identify a large photo-induced redistribution of electronic charge density, whose Coulombic interactions could explain the observed inter-layer contraction.

Characteristics and Evaluation of Zao IV Group of Kong I Zone in Zaobei Oilfield

2013 ◽  
Vol 295-298 ◽  
pp. 3281-3284
Author(s):  
Ying Hua Yu ◽  
Dan Dan Yuan ◽  
Xiao Yu Yang
Keyword(s):  
Physical Properties ◽  
Comprehensive Evaluation ◽  
Sedimentary Facies ◽  
Class Ii ◽  
Class I ◽  
Class Iii ◽  
Quality Difference ◽  
Relative Quality

Based on the characteristics of sedimentary facies, lithology, physical properties and heterogeneity for the reservoirs, a comprehensive evaluation for the reservoirs is researched, so as to determine the relative quality difference for different layers and different blocks, providing geological pursuant to the development of oilfield. The results show that Zao IV Group of Kong I Zone can be divided into three types, of which class I accounted for 26%, class II accounted for 42% and class III accounted for 32%, and reflected the strong degree of inhomogeneous of reservoir.

Physical properties of Class I methanol masers

2017 ◽  
Vol 13 (S336) ◽  
pp. 17-22 ◽  
Author(s):  
Silvia Leurini ◽  
Karl M. Menten
Keyword(s):  
Physical Properties ◽  
Recent Progress ◽  
Class Ii ◽  
Point Of View ◽  
Class I ◽  
Theoretical Point ◽  
The Past ◽  
Methanol Masers

AbstractAs first realised in the late 1980s, methanol masers come in two varieties, termed Class I and Class II. While Class II masers had observationally been extensively studied in the past, until recently relatively little attention was paid to Class I methanol masers due to their low luminosities compared to other maser transitions. In this review, we will focus on the recent progress in our understanding of Class I methanol masers both from an observational and from a theoretical point of view.

Optoelectronic and photocatalytic applications of hBP–XMY (M = Mo, W; (X ≠ Y) = S, Se, Te) van der Waals heterostructures

2020 ◽  
Vol 22 (40) ◽  
pp. 23028-23037
Author(s):  
Tahani A. Alrebdi ◽  
B. Amin
Keyword(s):  
Physical Properties ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Van Der Waals Heterostructures ◽  
Electronic Products ◽  
Photocatalytic Applications

Stacking of layers via weak van der Waals interactions is an important technique for tuning the physical properties and designing viable electronic products.

On the Forces between Micro and Nano Objects and a Gripper

2014 ◽  
pp. 612-628
Author(s):  
Galin Valchev ◽  
Daniel Dantchev ◽  
Kostadin Kostadinov
Keyword(s):  
Liquid Phase ◽  
Physical Properties ◽  
Van Der Waals ◽  
Van Der Waals Force ◽  
Van Der Waals Interactions

The authors study the van der Waals force FvdW, between the gripper jaw and an object – cubical, spherical and conical in shape, situated at a distance L of closest approach from it. The generic and most general case is considered, when the materials of the working jaw of the gripper and the particle are made of different materials strongly preferring the liquid phase of the fluid being at temperature T and chemical potentialm. The contributions due to the standard van der Waals, as well as of the retarded (Casimir) van der Waals interactions are considered. They concluded that FvdW strongly depends on the contrast, at given fixed T and m, between the physical properties of the fluid and the material of the arms of the gripper and the particle. In addition, as expected, FvdW strongly depends on the shape of the object, its size, and the distance L between it and the working jaw of the gripper. Their approach can be applied to any nonpolar fluid.

MANY-ATOM VAN DER WAALS INTERACTIONS LEAD TO DIRECTION-SENSITIVE INTERACTIONS OF COVALENT BONDS

2008 ◽  
Vol 06 (04) ◽  
pp. 693-707 ◽  
Author(s):  
ALEXEI V. FINKELSTEIN ◽  
MICHAEL Y. LOBANOV ◽  
NIKITA V. DOVIDCHENKO ◽  
NATALIA S. BOGATYREVA
Keyword(s):  
Physical Theory ◽  
Van Der Waals ◽  
Protein Structures ◽  
Covalent Bond ◽  
Covalent Bonding ◽  
Van Der Waals Interactions ◽  
Binding Affinities ◽  
Dispersion Interactions ◽  
Energy Effect ◽  
Covalent Bonds

Strict physical theory and numerical calculations show that a specific coupling of many-atom van der Waals interactions with covalent bonding can significantly (half as much) increase the strength of attractive dispersion interactions when the direction of interaction coincides with the direction of the covalent bond, and decrease this strength when the direction of interaction is perpendicular to the direction of the covalent bond. The energy effect is comparable to that caused by the replacement of atoms (e.g. N by C or O ) in conventional pairwise van der Waals interactions. Analysis of protein structures shows that they bear an imprint of this effect. This means that many-atom van der Waals interactions cannot be ignored in refinement of protein structures, in simulations of their folding, and in prediction of their binding affinities.

Electron microscopy analysis of degenerating pancreatic ß cells in transgenic mice expressing the MHC Class I antigen Dd

1990 ◽  
Vol 48 (3) ◽  
pp. 548-549
Author(s):  
T. A. Stewart ◽  
D. Liggitt ◽  
S. Pitts ◽  
L. Martin ◽  
M. Siegel ◽  
...  
Keyword(s):  
Type I Diabetes ◽  
Disease Process ◽  
Class Ii ◽  
Class I ◽  
Type I ◽  
Aberrant Expression ◽  
Mhc Molecules ◽  
Endogenous Insulin ◽  
Class Ii Mhc ◽  
Ifn Γ

Insulin-dependant (Type I) diabetes mellitus (IDDM) is a metabolic disorder resulting from the lack of endogenous insulin secretion. The disease is thought to result from the autoimmune mediated destruction of the insulin producing ß cells within the islets of Langerhans. The disease process is probably triggered by environmental agents, e.g. virus or chemical toxins on a background of genetic susceptibility associated with particular alleles within the major histocompatiblity complex (MHC). The relation between IDDM and the MHC locus has been reinforced by the demonstration of both class I and class II MHC proteins on the surface of ß cells from newly diagnosed patients as well as mounting evidence that IDDM has an autoimmune pathogenesis. In 1984, a series of observations were used to advance a hypothesis, in which it was suggested that aberrant expression of class II MHC molecules, perhaps induced by gamma-interferon (IFN γ) could present self antigens and initiate an autoimmune disease. We have tested some aspects of this model and demonstrated that expression of IFN γ by pancreatic ß cells can initiate an inflammatory destruction of both the islets and pancreas and does lead to IDDM.

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