Binary sulfur fluorides exhibit an interesting reactivity towards transition metal complexes. They open up routes for the generation of sulfur-containing building blocks. Often ligands with particular properties can be constructed. This includes their ability to transfer sulfur atoms or polysulfide units as well as fluorination reactions. This Minireview provides an insight into the reactivity of the binary and ternary sulfur halides S2Cl2, SCl2, SF4, SF6 and SF5Cl towards transition-metal compounds. 相似文献
Methyl methacrylate, benzyl methacrylate, butyl methacrylate, and methacrylic acid can be polymerized by 1, 2, 2-tetraphenyl-1, 2-diphenoxyethane (TPPA), 1, 1, 2, 2-tetraphenyl-1, 2-bis-(trimethylsiloxy) ethane (TPSA), and 1, 1, 2, 2-tetraphenyl-1, 2-dicyanoethane (TPCA) (1–3). The polymerization with these initiators is characterized by three steps; in the first period oligomers from MMA and initiator radicals are formed by primary radical termination. 相似文献
Graft copolymers have a potential as compatibilizers in two-component thermoplastic polymer blends, and also as impact-modifiers in one-component thermoplastics. The compatibility of the blocks of the copolymer (i.e. the grafts and the main chain) with the chains of the matrix polymers must be adjusted carefully. Blends of various polymers, especially of polystyrene (PS) and poly(vinyl chloride) (PVC), with graft copolymers on the basis of polybutadiene are discussed. An excellent compatibilizer, for blends PS/PVC, is a block-graft copolymer, derived from a diblock copolymer of Styrene and butadiene, with grafts of cyclohexyl methacrylate monomelic units. 相似文献
Molecular simulations and NMR relaxometry experiments demonstrate that pure benzene or xylene confined in isoreticular metal–organic frameworks (IRMOFs) exhibit true vapor–liquid phase equilibria where the effective critical point may be reduced by tuning the structure of the MOF. Our results are consistent with vapor and liquid phases extending over many MOF unit cells. These results are counterintuitive since the MOF pore diameters are approximately the same length scale as the adsorbate molecules. As applications of these materials in catalysis, separations, and gas storage rely on the ability to tune the properties of adsorbed molecules, we anticipate that the ability to systematically control the critical point, thereby preparing spatially inhomogeneous local adsorbate densities, could add a new design tool for MOF applications. 相似文献
A new way to fabricate monodisperse polymer particles in a microfluidic device without UV‐light and without the need for high temperatures is described in this article. By applying an activator regeneration by electron transfer ‐ atom transfer radical polymerization (ARGET‐ATRP) initiator system in a co‐capillary microfluidic setup and by separating the monomer mixture in an initiator and a catalyst phase, a fast polymerization of the droplets at low temperature without premature curing and thus clogging of the capillaries can be achieved. The influence of the flow rates on the particle sizes and their polydispersity as well as the controlled character of the polymerization are investigated. The particle size is well adjustable, but the reaction is not controlled due to the high radical concentration needed for rapid polymerization. In addition, particles with incorporated UV‐dyes are produced as a proof of concept at low temperature.
The following article describes an advanced dense wavelength division multiplexing (DWDM) Optical Network developed by L-3 Photonics. The network, configured as an amplified optical bus, carries traffic simultaneously in both directions, using multiple wavelengths. As a result, data distribution is of the form peer-to-multi-peer, it is protocol independent, and it is scalable. The network leverages the rapid growth in commercial optical technologies, including wavelength division multiplexing (WDM), and when applied to military and commercial platforms such as aircraft, ships, unmanned and other vehicles, provides a cost-effective, low-weight, high-speed, and high noise-immune data distribution system. 相似文献
Large-amplitude climate shifts, the so-called Dansgaard-Oeschger events, repeatedly occurred throughout the last ice age.
These events, which are apparently threshold-crossing events, show a reported tendency to recur preferably in near multiples
of about 1470 years. Several non-linear resonance mechanisms were proposed to explain this recurrence pattern in response
to noise and/or periodic forcing. Standard methods of linear time series analysis are not sufficient to distinguish between
these hypotheses, owing to the threshold-crossing dynamics of the events. Recently, new approaches were made by means of null-hypothesis
testing with Monte Carlo methods. A major hurdle in this approach is the need of efficient, but yet simple measures of regularity
that allow to distinguish between the proposed resonance mechanisms. By means of surrogate time series (i.e. by using a large
ensemble of Dansgaard-Oeschger events as simulated with a very simple two-state model) I here test the ability of three standard
measures of periodicity to distinguish between a scenario of solely noise-induced events and a ghost stochastic resonance
scenario. Only one measure is found to be applicable for that purpose. The choice of adequate measures, which is not trivial,
should be given more attention in future studies that focus on the question what triggered threshold-crossing events such
as Dansgaard-Oeschger events. 相似文献