Abstract In luftfreiem,doppelt destilliertem Wasser wird ein Gemisch aus Adenosin, ATP, ADP, AMP, Mg‐acetat, Dithiothreit und einer Suspension eines Adenosinkinase‐, Adenylatkinase‐ und Acetatkinase‐haltigen Gels beim pH 6.7‐6.9 l0 Tage lang unter Argon mit Diammoniumacetylphosphat umgesetzt.
No abstract is provided for this article.
Abstract Das Alkylbromid (I) reagiert in Diethylether bei 34°C in Gegenwart von tert.‐Butanol undTetramethylpiperidinoxyl‐Radikalen mit Mg hauptsächlich zum Kopplungsprodukt (II) und dem Alkan (III).
No abstract is provided for this article.
Field and laboratory observations show that shear deformation is often extremely localized at seismic slip rates, with a typical deforming zone width on the order of a few tens of microns. This extreme localization can be understood in terms of thermally driven weakening mechanisms. A zone of initially high strain rate will experience more shear heating and thus weaken faster, making it more likely to accommodate subsequent deformation. Fault zones often contain thermally unstable minerals such as clays or carbonates, which devolatilize at the high temperatures attained during seismic slip. In this paper, we investigate how these thermal decomposition reactions drive strain localization when coupled to a model for thermal pressurization of in situ groundwater. Building on Rice et al. (2014), we use a linear stability analysis to predict a localized zone thickness that depends on a combination of hydraulic, frictional, and thermochemical properties of the deforming fault rock. Numerical simulations show that the onset of thermal decomposition drives additional strain localization when compared with thermal pressurization alone and predict localized zone thicknesses of ∼7 and ∼13 μm for lizardite and calcite, respectively. Finally we show how thermal diffusion and the endothermic reaction combine to limit the peak temperature of the fault and that the pore fluid released by the reaction provides additional weakening of ∼20–40% of the initial strength.
The effects of non-planarity on the fracture resistance locus of interfaces has been investigated using a simple model of contacting facets along the crack surface. The contacts resist the motion of the crack surface by means of friction and locking and thereby modify the energy release rate G t at the crack front. The modified G t governs the effect of the contacting facets on the overall interface fracture resistance, G j . The trends in G j with phase angle of loading are found to be influenced largely by a non-dimensional parameter that determines the length of the contact zone. This parameter is, in turn, dependent on the amplitude of the undulations on the fracture interface as well as its intrinsic fracture resistance.
Delamination of residually stressed thin film strips is analyzed to expose the dependence on strip width and film/substrate elastic mismatch. Isotropic films and substrates are assumed. The residual stress in the film is tensile and assumed to originate from mismatch due to thermal expansion or epitaxial deposition. Full and partial delamination modes are explored. In full delamination, the interface crack extends across the entire width of the strip and releases all the elastic energy stored in the strip as the crack propagates along the interface. The energy release rate available to propagate the interface crack is a strong function of the strip width and the elastic modulus of the film relative to that of the substrate. The energy release rate associated with full delamination is determined as a function of the interface crack length from initiation to steady-state, revealing a progression of behavior depending in an essential way on the three dimensionality of the strip. The dependence of the energy release rate on the remaining ligament as the interface crack converges with the strip end has also been calculated, and the results provide an effective means for inferring interface toughness from crack arrest position. A partial delamination propagates along the strip leaving a narrow width of strip attached to the substrate. In this case, the entire elastic energy stored in the strip is not released because the strain component parallel to the strip is not relaxed. A special application is also considered, in which a residually stressed metal superlayer is deposited onto a polymer strip. The energy release rate for an interface crack propagating along the interface between the polymer and the substrate is determined in closed form.
The self-assembly of molecules into structurally organized monolayers (SAMs) uses the flexibility of organic chemistry and coordination chemistry to generate well-defined, synthetic surfaces with known molecular and macroscopic properties. The process of designing monolayers with a specified structure gives a high level of control over the molecular-level composition in the direction perpendicular to a surface; soft lithographic technique gives useful (if lower) resolution in the plane of the surface. Alkanethiolates adsorbed on gold, silver, mercury, palladium and platinum are currently the best-defined systems of SAMs. They provide substrates for a number of applications-from studies of wetting and electron transport to patterns for growing mammalian cells. SAMs have made organic surfaces a central part of surface science. Understanding the principles by which they form, and connecting molecular-level structure with macroscopic properties, opens a wide range of areas to study and exploitation.
Self-assembled monolayers (SAMs) formed on the adsorption of longchain alkanethiols to the surface of gold or alkylsilanes to hydroxylated surfaces are well-ordered organic surfaces that permit control over the properties of the interface at the molecular scale. The abililty to present molecules, peptides, and proteins at the interface make SAMs especially useful for fundamental studies of protein adsorption and cell adhesion. Microcontact printing is a simple technique that can pattern the formation of SAMs in the plane of the monolayer with dimensions on the micron scale. The convenience and broad application offered by SAMs and microcontact printing make this combination of techniques useful for studying a variety of fundamental phenomena in biointerfacial science.
