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。
Abstract Soil organic matter (SOM) in many tropical soils is less stable than that of temperate soils, in part due to faster decomposition processes in the tropics, but possibly also due to different mechanisms of organomineral stabilization. We studied the mineral associations of SOM in the surface horizons of two se…
Previously we reported P 2 W 15 Nb 3 O 62 9- polyoxoanion- and Bu 4 N + -stabilized, 20 ± 3 Å, Ir(0) ∼ 300 nanoclusters. These nanoscopic materials are synthesized from the reduction of [(C 4 H 9 ) 4 N] 5 Na 3 [(1,5-COD)M·P 2 W 15 Nb 3 O 62 ] (M = Ir) by H 2 in acetone and are isolable, highly catalytically active, wi…
The chemical synthesis of linear polyesters with various hydrophilic functional groups is difficult, involving a multistep reaction pathway and synthesis of a suitable monomer with a protected functional group. A straightforward conventional synthesis from a trifunctional compound, such as glycerol, and a diester or d…
Summary The rate at which minerals in the soil weather is affected by pH and concentration of organic solutes (DOC). The rates of release of Al, Ca, Fe, K, Mg, Na, P and Si from a mineral soil sample to solutions of natural organic solutes and HCI (control) were determined at pH 3 and 4 for up to 17 weeks. Soil soluti…
The resistivity in the ferromagnetic state of flux-grown ${\mathrm{La}}_{2/3}{(\mathrm{P}\mathrm{b},\mathrm{C}\mathrm{a})}_{1/3}{\mathrm{MnO}}_{3}$ single crystals, measured in magnetic fields up to 7 T, reveals a strong quadratic temperature dependence at and above 50 K. At lower temperatures, this contribution drops…
High-resolution NMR data for lithium and sodium in silicate, aluminosilicate, germanate, borate, and tellurite glasses and glass melts all show systematic effects of composition on isotropic chemical shift. The most reliable interpretation of these data is through well-established correlations of increased (higher fre…
Abstract We report the photogeneration of solitons and polarons in the quasi-one-dimensional (1-D) halogen (X)-bridged metal (M) compounds (simply abbreviated as the MX chain compounds). The most significant feature of this system is the remarkable tunability of the charge density wave (CDW) ground states. By substitu…
The early stages of crystallization are not fully understood, a particularly challenging problem being crystallization from solution. The processes involved at an atomic level remain elusive to experiment. Furthermore, crystallization from solution has been thought to be inaccessible by atomistic computer simulations.…
Particles of nanometer size (nanoparticles) supported on well-characterized oxide surfaces are of particular interest to model the high complexity of real catalysts to answer questions such as the role of intrinsic size effects and the influence of the support. 1,2 Model systems so far consisted of size-distributed na…
Synchrotron-based photoemission spectroscopy and low-energy electron diffraction were used to study the reaction of water vapor at 300 K and different water vapor pressures, p(H2O), ranging from 5×10−9 Torr to 10−3 Torr (3 min exposure at each pressure), with vacuum-cleaved MgO(100) surfaces that had low (5–10%) defec…
High-resolution NO3- profiles in freshwater sediment covered with benthic diatoms were obtained with a new microscale NO3- biosensor characterized by absence of interference from chemical species other than NO2- and N2O. Analysis of the microprofiles obtained indicated no nitrification during darkness, high rates of n…
The process of Ag colloid self-assembly onto organosilane-functionalized glass, carbon, and Au surfaces has been studied using UV−visible spectrophotometry, quartz crystal microgravimetry, and atomic force microscopy. Ag colloids prepared by citrate reduction and by ethylenediaminetetraacetic acid reduction of Ag + yi…
We show that the simplest model fluids in two and three dimensions, namely, the hard-disk and hard-sphere fluids, exhibit a structural precursor to the freezing transition, which manifests itself as a shoulder in the second peak of the radial distribution function. This feature is not present in the radial distributio…
Despite intensive investigations, the nature of the passive state is one of the most complex and unresolved subjects in the electrochemistry of zinc in alkaline solutions. In this paper, we explore the electrochemistry of the passive state on zinc in 0.1 M sodium borate/1 M sodium hydroxide solution of pH 10.5. During…
Within mode-coupling theory for structural relaxation in simple systems, the asymptotic laws and their leading-asymptotic correction formulas are derived for the motion of a tagged particle near a glass-transition singularity. These analytic results are compared with numerical ones of the equations of motion evaluated…
Ultrahigh-resolution X-ray diffraction data from cryo-cooled, B. lentus subtilisin crystals has been collected to a resolution of 0.78 A. The refined model coordinates have a rms deviation of 0.22 A relative to the same structure determined at room temperature and 2.0 A resolution. Several regions of main-chain and si…
A new phase, cubic ZrMo2O8, has been prepared by the low-temperature dehydration of ZrMo2O7(OH)2·2H2O. This material displays isotropic negative linear thermal expansion (α = −5.0 × 10-6 K-1) over a large temperature range. Unlike the previously reported cubic ZrW2O8, it does not undergo any phase transformations on h…
Infrared and Raman spectroscopy were used to characterize a chromate conversion coating (CCC) on 2024‐T3 aluminum aircraft alloy with a long range objective of determining the anticorrosion mechanism of the CCC. Spectra were compared to those from synthetic mixed oxides of aluminum, Cr(III), and Cr(VI) made by treatin…
The effects of environmental conditions and mechanical damage on the tensile stiffness and strength of two natural fibers, flax and nettle, are investigated. Flax and nettle both contain cellulosic fiber bundles in the outer layer of the plant, each bundle comprising many individual cells bonded together. Novel experi…
To model the phase behavior of polymer−clay composites, we develop a free energy expression for a mixture of polymers and solid, thin disks. The free energy expression is adopted from the Onsager model for the equilibrium behavior of rigid rods. Thus, our theory takes into account the possible nematic ordering of the…