Influence of free electron charge and free extra framework anions in calcium aluminate@ rGO (CA@ rGO) cement composites with enhanced dielectric and electrochemical properties

2021 ◽  
Author(s):  
Chesta Ruttanapun ◽  
Chaiwat Phrompet ◽  
Wattana Tuichai ◽  
Attaphol Karaphun ◽  
Sujittra Daengsakul ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Calcium Aluminate ◽  
Free Electron ◽  
Cement Composites ◽  
Electron Charge

A free-electron theory of conjugated molecules

1953 ◽  
Vol 49 (4) ◽  
pp. 650-658 ◽  
Author(s):  
J. Stanley Griffith
Keyword(s):  
Free Electron ◽  
Wave Functions ◽  
Electron Charge ◽  
Algebraic Equations ◽  
Electron Wave ◽  
Electron Theory ◽  
Conjugated Molecules ◽  
Electron Charge Density ◽  
Linear Polyenes ◽  
Alternant Hydrocarbons

ABSTRACTThe values of a free-electron eigenfunotion at the carbon nuclei of a conjugated hydrocarbon are found to satisfy a system of algebraic equations. These equations are similar in form to those obtained in the method known as the linear combination of atomic orbitale but only coincide with them for linear polyenes and benzene. The symmetry, degeneracy and energy of the eigenvectors of these free-electron equations correspond exactly to those of the free-electron wave functions found by the usual methods. From this correspondence, a theorem is deduced about the free-electron charge density in alternant hydrocarbons.

Effect of Boron Nitride on the Mechanical and Electrochemical Properties of Cement Composite

2015 ◽  
Author(s):  
Qinyue He ◽  
Xun Yu
Keyword(s):  
Corrosion Resistance ◽  
Boron Nitride ◽  
Electrochemical Properties ◽  
Hexagonal Boron Nitride ◽  
Water Solution ◽  
Cement Composite ◽  
Sodium Cholate ◽  
Ionic Surfactant ◽  
Cement Composites ◽  
Cement Concrete

Hexagonal boron nitride (h-BN) is well known for its unique properties, such as high thermal conductivity, excellent mechanical strength, high electrical insulating, and high chemical stability. This paper studies the effect of h-BN to the mechanical and electrochemical properties of cement concrete. Sodium cholate is used as an ionic surfactant to exfoliate h-BN and subsequently stabilize them in water solution. Different cement concrete samples with different doping levels of h-BN and different sizes of h-BN were prepared for comparisons. Also, steel fiber reinforced h-BN/cement concrete samples were also prepared. The results show that the addition of h-BN can improve the strength of cement composites, and the degree of reinforcement are influenced by the doping levels and feature size of h-BN. The corrosion resistance of h-BN/cement composites were also tested. Experiments results show that h-BN can enhance the corrosion resistance of cement composites.

scholarly journals New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

2017 ◽  
Vol 13 ◽  
pp. 1583-1595 ◽  
Author(s):  
Daria G Selivanova ◽  
Alexei A Gorbunov ◽  
Olga A Mayorova ◽  
Alexander N Vasyanin ◽  
Igor V Lunegov ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electrochemical Properties ◽  
Electrochemical Oxidation ◽  
Free Electron ◽  
Quantum Yields ◽  
Synthetic Approach ◽  
Fluorescence Quantum Yields ◽  
Starting Compound ◽  
Positive Solvatochromism

In this paper we present a synthetic approach to six new D–π–A–D conjugated chromophores containing the N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment. Such readily functionalizable heterocycle as carbazole was used as a main starting compound for their preparation. The investigation of the optical properties has shown that the positive solvatochromism is inherent to the chromophores containing an electron-withdrawing prop-2-en-1-one fragment, while the compounds containing a 2-aminopyrimidine moiety exhibit both positive and negative solvatochromism. The fluorescence quantum yields were experimentally determined for some of the synthesized chromophores; e.g., 1-(5-arylthiophen-2-yl)ethanones quantum yields were found to lie in an interval of 60–80%. Electrochemical oxidation of the synthesized chromophores has resulted in the formation of colored thin oligomeric films that became possible due to the presence of carbazole or pyrrole fragments with free electron-rich positions.

Cross-Linking Reactions in Macro-Defect Free Cement Composites

1991 ◽  
Vol 245 ◽  
Author(s):  
P. G. Desai ◽  
J. F. Young ◽  
R. P. Wool
Keyword(s):  
Polyvinyl Alcohol ◽  
Calcium Aluminate ◽  
Polymer Solutions ◽  
Cross Linking ◽  
Cement Composites ◽  
Cross Link ◽  
Pva Solutions

ABSTRACTThe key to the processing and properties of Macro-Defect Free (MDF) cement composites is the interaction between the cement and the polymer. In calcium aluminate (CA) / polyvinyl alcohol (PVA) MDF composites, it has been hypothesized that aluminate (Al(OH)4−) ions released from the cement cross-link PVA in a manner similar to the well known interaction of the borate (B(OH)4−) ions with PVA. In this investigation, stable aluminate/PVA solutions at different concentrations have been studied. Results indicate that the nature of interaction of aluminate ions is not similar to that of borate ions in dilute and semidilute polymer solutions.

Artifact-free electron microscopic immunocytochemistry on rat brain tissue

1991 ◽  
Vol 49 ◽  
pp. 272-273
Author(s):  
Veronika Burmeister ◽  
N. Ludvig ◽  
P.C. Jobe
Keyword(s):  
Microscopic Examination ◽  
Free Electron ◽  
Electron Microscopic Examination ◽  
Ultrastructural Localization ◽  
Rabbit Serum ◽  
Electron Microscopic ◽  
Electron Microscopic Immunocytochemistry ◽  
Phosphate Buffered Saline ◽  
Rat Brain Tissue ◽  
Immune Rabbit

Electron microscopic immunocytochemistry provides an important tool to determine the ultrastructural distribution of various molecules in both normal and pathologic tissues. However, the specific immunostaining may be obscured by artifactual immunoreaction product, misleading the investigator. Previous observations show that shortening the incubation period with the primary antibody from the generally used 12-24 hours to 1 hour substantially reduces the artifactual immunostaining. We now extend this finding by the demonstration of artifact-free ultrastructural localization of the Ca2/calmodulindependent cyclic nucleotide phosphodiesterase (CaM-dependent PDE) immunoreactivity in brain.Anesthetized rats were perfused transcardially with phosphate-buffered saline followed by a fixative containing paraformaldehyde (4%) and glutaraldehyde (0.25%) in PBS. The brains were removed, and 40μm sections were cut with a vibratome. The sections were processed for immunocytochemistry as described by Ludvig et al. Both non-immune rabbit serum and specific CaM-dependent PDE antibodies were used. In both experiments incubations were at one hour and overnight. The immunostained sections were processed for electron microscopic examination.

An HREM study of superstructures in Ca4Al6SO16

1990 ◽  
Vol 48 (4) ◽  
pp. 1066-1067
Author(s):  
Y.G. Wang ◽  
H.Q. Ye ◽  
K.H. Kuo
Keyword(s):  
Calcium Aluminate ◽  
Structural Model ◽  
Bright Spot ◽  
Sulphur Atom ◽  
Synthetic Compound ◽  
Space Group ◽  
Lattice Images ◽  
Cubic Structure ◽  
Good Agreement

A synthetic compound Ca4Al6SO16 (usually abbreviated as C4A3S) obtained by mixing CaO, A12O3 and CaSO4 powders and finally sintered at 1380°C is a cement with excellent hydraulicity and greatly expanding in application. It is hydralysed rapidly by water to form predominatly calcium aluminate hydrates and therefore unlikly to occur naturally, although structurally it may be regarded as an end member of the sodalite-hauynite series of naturally occuring minerals. C4A3S has a cubic structure with ao=9.19Å and space group . Fig.1 is the projection viewed down axis, in which there are two sets of 8C position in , namely CaI and CaII, occupied by the calcium atoms, respectively, and the ratio of occupations in these two sets of positions is about 3:1. This suggests that the calcium atoms can freely occupy these sites in various degrees and usually they almost locates on the CaI positions. A through-focus series of the lattice images were found in good agreement with the simulated ones. Each bright spot in the image taken at Scherzer defocus correspounds to a colunm of sulphur atom in the structural model (Fig.1).

Sign in / Sign up

Export Citation Format

Share Document