Water‐Tolerant Solid Acid Catalysts
Abstract For Abstract see ChemInform Abstract in Full Text.
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。
DPX: for the analysis of the protein core
SUMMARY: In order to obtain an accurate description of the protein interior, we describe a simple and fast algorithm that measures the depth of each atom in a protein (dpx), defined as its distance (A) from the closest solvent accessible atom. The program reads a PDB file containing the atomic solvent accessibility in…
Unusual, Vesicle-like Patterned, Mesoscopically Ordered Silica
A mixture of cationic and anionic surfactants has been used as structure-directing agents in the synthesis of mesoscopically ordered silica in the presence of toluene. The preferred interfacial curvature was adjusted by varying the anionic/cationic surfactant molar ratio, which allowed for better control of the solubi…
Phase-field approach to heterogeneous nucleation
We consider the problem of heterogeneous nucleation and growth. The system is described by a phase-field model in which the temperature is included through thermal noise. We show that this phase-field approach is suitable to describe homogeneous as well as heterogeneous nucleation starting from several general hypothe…
Evaluation of the free‐volume theory of diffusion
Abstract General characteristics of the free‐volume theory of diffusion are discussed, and a recent data‐theory comparison involving free‐volume theory is critically evaluated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 501–507, 2003
Dynamic mechanical study on the thermal aging of a hydroxyl‐terminated polybutadiene‐based energetic composite
Abstract In an attempt to determine the aging behavior of hydroxyl‐terminated polybutadiene‐based composite solid propellants, viscoelastic measurements were used to study the effect of thermal aging on this kind of energetic material. Accelerated‐aging tests at 40, 60, and 80°C were performed for 5000 h. The changes…
Fundamentals of Polymer Engineering, Revised and Expanded
Exploring the characterization, thermodynamics and structural, mechanical, thermal and transport behavior of polymers as melts, solutions and solids, this text covers essential concepts and breakthroughs in reactor design and polymer production and processing. It contains modern theories, end-of-chapter problems and r…
Photoassisted Selective Catalytic Reduction of NO with Ammonia in the Presence of Oxygen over TiO2
Selective catalytic reduction (SCR) of NO with NH 3 in the presence of O 2 takes place over titanium oxide under photoirradiation at low temperature. The active site of TiO 2 is suggested to be the Ti 4+ Lewis acid site. TiO 2 exhibits the weak Lewis acid property. NH 3 is adsorbed easily on the Lewis acid site as com…
A heating stage up to 1173 K for X-ray diffraction studies in the whole orientation space
A multi-purpose heating attachment designed primarily for X-ray four-circle diffractometers but applicable also for classical powder diffraction is presented. When working in reflection geometry, the air-cooled heating stage allows diffraction studies to be performed on plate-like samples up to 1173 K in the whole ori…
Atomic positional disorder in fcc metal nanocrystalline grain boundaries
We investigate the degree of grain boundary positional disorder in computer generated fcc nc-Ni samples, as a function of grain size. We find that these grain boundary atoms display a lack of a second peak in the pair distribution function by virtue of their classification, and find further that such a class of atoms…
Primary Alkyl Amines as Latent Gelators and Their Organogel Adducts with Neutral Triatomic Molecules
A series of organogelator salts has been prepared from n -alkylamines by the rapid in situ and isothermal (at room temperature) uptake of a neutral triatomic molecule, CO 2, NO 2, SO 2, or CS 2 . The organogels have been examined by differential scanning calorimetry, optical microscopy, and X-ray diffraction methods.…
Polymeric Complexes with “Piperazine−Pyridine” Building Blocks: Synthesis, Network Structures, and Third-Order Nonlinear Optical Properties
A new bidentate “building block”, N,N ‘ -bis(3-pyridylformyl)piperazine (bpfp), was synthesized. X-ray diffraction studies reveal that the piperazine ring in bpfp forms a chairlike structure conformation. bpfp self-assembled into two-dimensional layered rhombohedral grid polymers {[Mn(H 2 O) 2 (SO 4 )(bpfp)](H 2 O) 3…
Ionization and pH Stability of Multilayers Formed by Self-Assembly of Weak Polyelectrolytes
The formation of polyelectrolyte multilayers using the layer-by-layer sequential self-assembly of a weak polybase and polyacid onto a surface of Si crystal and their stability under acidic conditions were studied. The system was 12%, 20%, 25%, 37%, 90%, or 98% quaternized poly-4-vinylpyridine (Q12, Q20, Q25, Q37, Q90,…
Density Functional and Reduction Potential Calculations of Fe 4 S 4 Clusters
Density functional theory geometry optimizations and reduction potential calculations are reported for all five known oxidation states of [Fe(4)S(4)(SCH(3))(4)](n)()(-) (n = 0, 1, 2, 3, 4) clusters that form the active sites of iron-sulfur proteins. The geometry-optimized structures tend to be slightly expanded relati…
Improved measures of quality for the atomic pair distribution function
The introduction of neutron spallation-source instruments, such as the General Materials Diffractometer (GEM) at ISIS, allows measurement of pair distribution function (PDF) data at significantly higher rates than previously possible. As a result of the increased rate, a single experiment can produce over a hundred in…
How root-mean-square distance (r.m.s.d.) values depend on the resolution of protein structures that are compared
The most popular estimator of structural similarity is the root-mean-square distance (r.m.s.d.) between equivalent atoms, computed after optimal superposition of the two structures that are compared. It is known that r.m.s.d. values do not depend only on conformational differences but also on other features, for examp…
Photonic band gaps in materials with triply periodic surfaces and related tubular structures
We calculate the photonic band gap of triply periodic bicontinuous cubic structures and of tubular structures constructed from the skeletal graphs of triply periodic minimal surfaces. The effect of the symmetry and topology of the periodic dielectric structures on the existence and the characteristics of the gaps is d…
Quantum size effects in the low temperature layer-by-layer growth of Pb on Ge(001)
The electronic properties of thin metallic films deviate from the corresponding bulk ones when the film thickness is comparable with the wavelength of the electrons at the Fermi level due to quantum size effects (QSE). QSE are expected to affect the film morphology and structure leading to the low temperature (LT) ``e…
Thermoelectric Power of Insulators and Reconsideration of Kelvin's Relations at Low Temperatures
Thermoelectric effects in Kondo insulators are attracting interests because of the emerging possibility of developping better thermoelectric materials for a portable refrigerator without liquid coolant. In this article, the theory of thermoelectric effects are reinvestigated for insulators or semiconductors at low tem…
Charge ordering in oxides : a conundrum solved by resonant diffraction
We show that in mixed-valence 3d transition metal oxides undergoing a structural transition, the low temperature phase results from an effective ordering of the charge. This arrangement and the quantitative evaluation of the atomic charges are determined by using resonant x-ray scattering experiments further analyzed…