The Sol-Gel Preparation of Silica Gels
Background and procedure for the sol-gel preparation of silica from molecular precursors.
Materials Literature
文献浏览
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Dynamics of hard-sphere suspensions
A systematic theory for the dynamics of concentrated hard-sphere suspensions of interacting Brownian particles with both hydrodynamic and direct interactions is presented. An alternative equation for the number density of particles is derived. The volume-fraction dependence of the short- and long-time self-diffusion c…
Force field for computation of conformational energies, structures, and vibrational frequencies of aromatic polyesters
Abstract A CFF93 1 all‐atom force field for aromatic polyesters based on ab initio calculations is reported. The force field parameters are derived by fitting to quantum mechanical data which include total energies, first and second derivatives of the total energies, and electrostatic potentials. The valence parameter…
Domain configurations due to multiple misfit relaxation mechanisms in epitaxial ferroelectric thin films. I. Theory
Possible mechanisms for strain relaxation in ferroelectric thin films are developed. The models are applicable to tetragonal thin film ferroelectrics grown epitaxially on (001) cubic single crystal substrates. We assume growth at temperatures in excess of the Curie temperature (Tc). The extent of strain accommodation…
Generation of microcellular polymeric foams using supercritical carbon dioxide. I: Effect of pressure and temperature on nucleation
Abstract Supercritical carbon dioxide is known to swell and plasticize poly(methyl methacrylate), PMMA, dramatically. We have employed a pressure quench in a CO 2 ‐swollen PMMA sample to generate a microcellular core structure encased by a nonporous skin. Further, we have demonstrated that classical nucleation theory…
Phenomenological study of the size effect on phase transitions in ferroelectric particles
Size effects on the Curie temperature and spontaneous polarization in spherical particles are studied using Landau phenomenological theory. The extrapolation length is shown to be size dependent. The spatial distribution of polarization is obtained. The size dependence of the polarization is calculated whereby a size-…
Characterization of NiO by XPS
We report x-ray photoemission spectra (XPS) of nickelous oxide (NiO). XPS spectra were measured with the Physical Electronics Model 5400 x-ray photoelectron spectrometer using unmonochromatized Mg Kα x rays at two pass energy settings corresponding to analyzer energy resolutions of 1.34 and 0.54 eV. We present the sur…
Predicting protein crystallization from a dilute solution property
A dilute solution parameter obtained from static light-scattering measurements is proposed as a predictor for protein crystallization experiments. The osmotic second virial coefficients, B(22), have been measured for a variety of proteins in solvents that are known to promote crystallization and the values for B(22) w…
Mechanical degradation and viscous dissipation inB2O3
The Brillouin light scattering technique was used to determine the complex mechanical modulus, which describes the dynamic response of molecular structures, for ${\mathrm{B}}_{2}$${\mathrm{O}}_{3}$ and binary alkali borate. The effects of temperature, alkali concentration, oxygen and water vapor partial pressures on t…
Dielectric and Structural Characteristics of Ba- and Sr-based Complex Perovskites as a Function of Tolerance Factor
The temperature coefficient of the dielectric permittivity (τ ε ) of nonferroelectric complex perovskites is of importance in the application of these cermaics to microwave filters and resonators. Recent work has directly related changes in the τ ε of complex perovskites to the onset of structural phase transitions wh…
The Gyroid: A New Equilibrium Morphology in Weakly Segregated Diblock Copolymers
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Gyroid: A New Equilibrium Morphology in Weakly Segregated Diblock CopolymersDamian A. Hajduk, Paul E. Harper, Sol M. Gruner, Christian C. Honeker, Gia Kim, Edwin L. Thomas, and Lewis J. FettersCite this: Macromolecules 1994, 27, 15, 4063–4075Publication Date (Print):July…
Interlayer Structure and Molecular Environment of Alkylammonium Layered Silicates
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInterlayer Structure and Molecular Environment of Alkylammonium Layered SilicatesRichard A. Vaia, Rachel K. Teukolsky, and Emmanuel P. GiannelisCite this: Chem. Mater. 1994, 6, 7, 1017–1022Publication Date (Print):July 1, 1994Publication History Published online1 May 2002Pub…
Microvascular permeability and interstitial penetration of sterically stabilized (stealth) liposomes in a human tumor xenograft.
Microvascular permeability and interstitial penetration of sterically stabilized liposomes in both normal s.c. tissue and human colon adenocarcinoma LS174T xenograft were quantified by using the dorsal skin-fold chamber implanted in severe combined immunodeficient mice and intravital fluorescence microscopy. Significa…
Size-Dependent Depression of the Glass Transition Temperature in Polymer Films
The glass transition temperature of thin polystyrene films has been measured as a function of film thickness. It is found that the glass transition decreases in temperature as the thickness of the film is reduced. The effect is not strongly molecular-weight dependent, ruling out chain confinement as the major cause; i…
Macroscopic polarization in crystalline dielectrics: the geometric phase approach
The macroscopic electric polarization of a crystal is often defined as the dipole of a unit cell. In fact, such a dipole moment is ill defined, and the above definition is incorrect. Looking more closely, the quantity generally measured is differential polarization, defined with respect to a "reference state" of the s…
Untersuchung der thermisch-oxidativen Stabilität von Gasölen mittels Druckdifferenz-Kalorimetrie (PDSC)
Thermoanalytical techniques have found widespread use as a quality-control tool for petroleum and related products. Pressure differential scanning calorimetry (PDSC) has been effectively used as an alternative method to estimate thermal-oxidation stability of middle-destillate fuels. In this paper, the fuels were rate…
Syntheses of Segmental Heteroleptic Ligands for the Self‐Assembly of Heteronuclear Helical Supramolecular Complexes
Abstract The development of a modified Phillips reaction allows the synthesis of complicated heteroleptic ligands based on pyridine and 1 H ‐benzimidazole moieties. The key‐step formation of aromatic 1 H ‐benzimidazole rings from N ‐(2‐nitroaryl)arenecarboxamides significantly improves the possibilities of the classic…
Corrosion Resistance of Zinc and Zinc Alloys
A cornerstone reference in the field, this work analyzes available information on the corrosion resistance of zinc and its alloys both as solid materials and as coatings on steel, detailing the corrosion resistance of zinc in atmospheric, aqueous, underground and chemical environments. Corrosion Resistance of Zinc and…
A Very Short Hydrogen Bond Provides Only Moderate Stabilization of an Enzyme-Inhibitor Complex of Citrate Synthase
Two extremely potent inhibitors of citrate synthase, carboxyl and primary amide analogues of acetyl coenzyme A, have been synthesized. The ternary complexes of these inhibitors with oxaloacetate and citrate synthase have been crystallized and their structures analyzed at 1.70- and 1.65-A resolution, respectively. The…
Differential and total electron scattering from neon at low incident energies
Absolute differential (in angle) and total scattering cross sections for low-energy (0.1-7.0 eV) electron scattering from neon have been measured. Both data sets have been analysed using phaseshift techniques and comparisons are made between the present cross sections and phaseshifts and similar data from previous swa…