Materials Literature
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Phosphane-stabilized copper – mercury – sulfide clusters have been prepared with a powerful strategy for the formation of ternary clusters and colloids. A series of terminal copper – (trimethylsilyl)chalcogenolate complexes 1 have been synthesized and treatment of 1 a with Hg(OAc)2 at low temperatures results in the f…
This contribution deals with test probes with flat cavities (height of gap h = 0.5 mm), which arise in reality from delamination processes caused by thermal expansion. These test probes are aged by means of partial discharges (pds). The different changes on the cavity's surface, for example the development of surface…
The degree of polymerisation (DP) of electrical insulation paper is an invaluable tool for assessing its condition and is extensively used in laboratory tests to assess the life expectancy of transformer insulation. Accurate and reproducible determinations are essential if the results are to be used to calculate a mea…
A pattern recognition method for localisation of the partial discharge (PD) site in an oil-filled transformer by acoustic measurements is presented. By dividing the transformer into a number of 20 × 20 × 20 mm3 sub-modules, the PD site is localised by comparing the spatial distance of each sub-module to the acoustic s…
A wide-ranging and varied group of 31 even−even nylons, in the form of adjacent, re-entry chain-folded lamellar crystals, are compared and contrasted with respect to their room-temperature structures and behavior on heating. In this comparison, various relationships and trends emerge that provide a clearer understandi…
Abstract. X-ray diffraction has been used to characterize the amorphous phase present in a series of radiation-damaged natural zircons with radiation doses ranging from 0.06 to 16 × 1018 α-decay events g−1. The fraction of amorphous material present in each of the samples studied has been determined, and its dependenc…
Two new polymeric manganese-azido systems with formula Cs(n)-[[Mn(N3)3]n] (1) and [[N(C2H5)4]n][[Mn2-(N3)5(H2O)]n] (2) were synthesised and structurally characterised. Compound 1 crystallises in the P2(1)/n group and consists of a three-dimensional system with end-to-end and end-on azido bridges with the caesium atoms…
We adopt an atomistic pseudopotential description of the electronic structure of self-assembled, lens shaped InAs quantum dots within the ``linear combination of bulk bands'' method. We present a detailed comparison with experiment, including quantites such as the single particle electron and hole energy level spacing…
Dendrimers are presently one of the most intensely studied classes of compounds because of their unusual structure. They can be described as a jungle of entangled branches traversed by winding trails which lead to sweet fruits and bright blossoms. On these trails one can reach the thicket's interior as well as find a…
We used the Schwinger multichannel method with pseudopotentials [Bettega et al., Phys. Rev. A 47, 1111 (1993)] to study elastic scattering of low-energy electrons by the boron trihalides ${\mathrm{BCl}}_{3},$ ${\mathrm{BBr}}_{3},$ and ${\mathrm{BI}}_{3},$ at the static-exchange approximation. We calculated elastic int…
We present an exact derivation of a process in which a microscopic measured system interacts with heat-bath and pointer modes of a measuring device, via a coupling involving a general Hermitian operator $Λ$ of the system. In the limit of strong interaction with these modes, over a small time interval, we derive the ex…
Formation of monodispersed colloidal particles is a complex process: nuclei, produced rapidly in a supersaturated solution, grow to nanosize primary particles, which then aggregate (coagulate) to form much larger final colloids. This paper reviews a kinetic model that explains the formation of dispersions of narrow si…
Recent spectroscopic results in the emerging area of transition-metal NIR-to-visible upconversion are related. The examples of Ti(2+)-, Re(4+)-, and Os(4+)-doped materials showing upconversion illustrate GSA/ESA, GSA/ETU, and photon avalanche multiphoton excitation mechanisms, respectively. Strategies for manipulation…
The thermal expansion coefficients of $\mathrm{Na}_{N}$ clusters with $8 \le N \le 40$ and $\mathrm{Al}_{7}$, $\mathrm{Al}_{13}^-$ and $\mathrm{Al}_{14}^-$ are obtained from {\it ab initio} Born-Oppenheimer LDA molecular dynamics. Thermal expansion of small metal clusters is considerably larger than that in the bulk a…
Many systems where interactions compete with each other or with constraints are well described by a model first introduced by Brazovskii. Such systems include block copolymers, alloys with modulated phases, Rayleigh-Benard Cells and type-I superconductors. The hallmark of this model is that the fluctuation spectrum is…
We study metallization of molecular hydrogen under pressure using exact exchange (EXX) Kohn-Sham density-functional theory in order to avoid well-known underestimates of band gaps associated with standard local-density or generalized-gradient approximations. Compared with the standard methods, the EXX approach leads t…
The ferrodistortive phase transition in the bis-tetramethylammonium tetrabromide crystals below room temperature is studied within the framework of the Landau theory. The specific heats of [N(CH3)4]2MnBr4 and [N(CH3)4]2ZnBr4 are correctly described down to 40°C below the transition temperature. The phenomenological pa…
The usual tiling problem determines which polygons can be used to cover the plane exactly without overlaps or gaps. We consider two variations of that problem. The first attempts to determine polygons that can tile the plane by reflections as in a kaleidoscope. The second determines polygons that can be used to create…
Article Entwicklung eines elektrolytischen Ätzverfahrens zur Charakterisierung der Magnesiumlegierung AZ 91 hp für den Thixogießprozess / The Development of an Electrolytic Etching Process for Examining the Microstructure of Thixocast Magnesium Alloy AZ91 hp was published on March 1, 2000 in the journal Practical Meta…
Magnetic field analysis of a permanent magnet put in free space can be effectively performed by a boundary‐integral technique completed with an iterative procedure following a non‐linear magnetic curve of magnetic material. The general idea of the boundary‐integral model of the permanent magnet is presented, the itera…