Materials Literature
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。
We describe a new continuum approach to the modelling of stress propagation in static granular media, focussing on the conical sandpile created from a point source. We argue that the stress continuity equations should be closed by means of scale-free, local constitutive relations between different components of the st…
We report a 10-Hz, highly efficient, widely tunable (from the visible to the IR), broadband femtosecond optical parametric generator and optical parametric amplifier (OPA) in BBO, LBO, and CBO crystals pumped by the frequency-doubled output of a regeneratively amplified Ti:sapphire laser at 400 nm. The output of the s…
Laser ablation into vacuum of a dilute dispersion of AmO 2 in polyimide produced organoamericium ions of the general formula AmC x H y N z + . Ion masses were determined by time-of-flight mass spectrometry, and compositions were confidently assigned for most small ions ( x ≤ 6). Comparisons of product abundances with…
An approach to the analysis of the plate-type catalysts for high-dust selective catalytic reduction (SCR) applications is herein presented. Commercial systems were studied in the form of slabs. NO x reduction and SO 2 oxidation runs were performed spanning a wide range of operating conditions. The results were analyze…
Ultrasmall light modulators have been made by sandwiching a polymer-dispersed liquid crystal (PDLC) between two ferrules with optical fibers. The device can modulate light independent of the state of polarization, because the PDLC becomes transparent or opaque when either sufficient or no voltage is applied to the fil…
Geometry optimizations were carried out for the cis and trans forms of Nb 2 W 4 O 19 4 - . The energy difference between the two conformations was found to be 2.3 kcal mol - 1, the structure in which the two Nb atoms are in the cis formation being the most stable. Several isomers of the Nb 2 W 4 O 19 H 3 - anion were…
To obtain insights into the factors that influence the electronic spectra of conjugated porphyrin systems, a series of porphyrins with fused phenanthrene subunits have been synthesized. 9-Nitrophenanthrene reacted with esters of isocyanoacetic acid in the presence of DBU in THF to give a series of phenanthro[9,10- c ]…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTTight Knots in PolymersMarc L. MansfieldView Author Information Michigan Molecular Institute, 1910 W. St. Andrews Road, Midland, Michigan 48640 Cite this: Macromolecules 1998, 31, 12, 4030–4032Publication Date (Web):May 20, 1998Publication History Received6 January 1998Publishe…
In this study, we select a catalyst with the highest activity to reduce NO with CO as a reducing reactant from four series of perovskites La 1 - x Sr x BO 3 where B = Mn, Fe, Co, or Ni. The cause for different activities is also closely examined by characterizing the perovskites by XRD, XPS, NO-TPD, and CO-TPR. Activi…
Experiments using a blunted conical indentor show that the low-density amorphous solid form of pressure-amorphized ice deforms under load and behaves like a viscous liquid near 143 K, much before its rapid crystallization to cubic ice. Since a mechanical stress biases the molecular diffusion of a fluid undergoing a Ne…
Bacterial Delta 5-3-ketosteroid isomerase (KSI) from Pseudomonas testosteroni has been intensively studied as a prototype for understanding an enzyme-catalyzed allylic rearrangement involving intramolecular proton transfer. Asp38 serves as a general base to abstract the proton from the steroid C4-H, which is a much st…
The crystalline carbon nanotubes having mesopores that are open at one end, with pore width of 4 ± 0.8 nm, were characterized by XRD, XPS, and HRTEM. The N 2 adsorption isotherm of multiwall carbon nanotubes was measured at 77 K. A hump was observed near P / P 0 = 0.4 in the adsorption isotherm. The adsorption isother…
We report the results of extensive Dynamic Monte Carlo simulations of systems of self-assembled Equilibrium Polymers without rings in good solvent. Confirming recent theoretical predictions, the mean-chain length is found to scale as $\Lav = \Lstar (ϕ/\phistar)^α\propto ϕ^α\exp(δE)$ with exponents $α_d=δ_d=1/(1+γ) \ap…
We consider the growth of a polymer layer on a flat surface in a good solvent by in-situ polymerization. This is viewed as a modified form of diffusion-limited aggregation without branching. We predict theoretically the formation of a pseudo-brush with density rhog(z) \propto z^{-2/3} and characteristic height \propto…
Unconcatenated, unknotted polymer rings in the melt are subject to strong interactions with neighboring chains due to the presence of topological constraints. We study this by computer simulation using the bond-fluctuation algorithm for chains with up to N=512 statistical segments at a volume fraction Φ=0.5 and show t…
We report results of extensive Dynamical Monte Carlo investigations on self-assembled Equilibrium Polymers (EP) without loops in good solvent. (This is thought to provide a good model of giant surfactant micelles.) Using a novel algorithm we are able to describe efficiently both static and dynamic properties of system…
Si anodic dissolution in acidic fluoride medium has been investigated in different regimes (porous silicon formation, electropolishing under stationary and oscillating current) by probe beam deflection (PBD) or the “mirage” technique. Evolution of deflection signal allows monitoring of dissolution processes both under…
A simple model is proposed to calculate the charge distribution in the two-electron-reduced isopolytungstate [W10O32].6- It is shown that the experimentally observed asymmetric excess electron distribution is due to competition of the electronic delocalization between equatorial metal sites and Coulomb repulsion.
Polyethylene glycol (PEG)-linked manganese halogenated porphyrins (Chart 1) catalyzed oxidation of azo dyes (Chart 2) by H 2 O 2 under mild conditions such as pH 8.0 at 25 °C especially when imidazole was present, causing the decoloration of azo dyes. The decoloration of azo dyes by synthetic manganese porphyrins unde…
Dielectric measurements were carried out on undiluted cis -polyisoprene (PI) over a wide frequency range from 10 -4 to 10 5 Hz around the glass transition temperature T g (=200 K). The data indicate that the dielectric loss curves including both the normal and segmental mode processes are superposable in the range abo…