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Veranstaltungen / Calendar

Zweiter Rheology-Preis / Second Rheology Prize

lm Norden viel Neues / New happenings in the North

Electropolymerization of 1,4‐bis(Pyrrol‐2‐yl)benzene in the Presence of the Easily Oxidized Electrolyte Sodium Tetraphenylborate

The low oxidation potential of 1,4‐bis(pyrrol‐2‐yl)benzene (BPB) at 0.25 V vs. allows its electropolymerization in the presence of easily oxidized electrolytes, such as sodium tetraphenylborate . In contrast, the electropolymerization of pyrrole under the same conditions is unsuccessful due to electrolyte breakdown. T…

Generalized Coddington equations in ophthalmic lens design

A matrix equation for the refraction of a thin pencil of rays by a surface of arbitrary shape is derived. The equivalence of this equation and previous nonmatrix equations derived for the same purpose is established. Potential applications of this matrix equation are in the field of ophthalmic lens design. The design…

Power Conversion Efficiency, Electrode Separation, and Overpotential in the Ferricyanide/Ferrocyanide Thermogalvanic Cell

The effect of electrode separation on the power conversion efficiency of a ferricyanide/ferrocyanide thermogalvanic cell containing platinum electrodes was studied at electrode separations up to 150 cm, using the “cold‐above‐hot” electrode configuration. The open‐circuit potential difference is almost independent of e…

First-principles study of stability and vibrational properties of tetragonalPbTiO3

A first-principles study of the vibrational modes of ${\mathrm{PbTiO}}_{3}$ in the ferroelectric tetragonal phase has been performed at all the main symmetry points of the Brillouin zone (BZ). The calculations use the local-density approximation and ultrasoft pseudopotentials with a plane-wave basis, and reproduce wel…

Tensile behavior of nanocomposites from latex and cellulose whiskers

Abstract Cellulose whiskers have been used as reinforcement in a copolymer matrix prepared from a latex phase. If a water suspension‐mixing procedure is adopted, the fibril breakage that usually occurs during the mixing with a molten polymer can be avoided, and an enhanced filler dispersion can be expected. In this st…

Mechanical Characterization of Sol–Gel‐Derived Silicon Oxycarbide Glasses

Silicon oxycarbide glasses have been fabricated, in the shape of thin rods suitable for flexural test experiments, by pyrolysis in an inert atmosphere at 1000° and 1200°C of solgel precursors containing Si–CH 3 and Si–H bonds. The amount of carbon in the silicon oxycarbide network has been controlled by varying the ca…

Below Band-Gap IR Response of Substrate-Free GaAs Solar Cells Using Two-Photon Up-Conversion

We have developed a device based upon the concept of two-photon up-conversion to use a part of the IR photons otherwise lost by transparency in a GaAs cell. An ultra thin GaAs cell has been fabricated using the technique of epitaxial lift-off (ELO). This thin cell is placed on top of a 100 µ m thick vitroceramic doped…

Electrochemical Studies on LaNi5 − x Sn x Metal Hydride Alloys

Electrochemical studies were performed on LaNi 5 − x Sn x with 0 ⩽ x ⩽ 0.5 . We measured the effect of the Sn substituent on the kinetics of charge‐transfer and diffusion during hydrogen absorption and desorption, and the cyclic lifetimes of LaNi 5 − ‐ x Sn x electrodes in 250 mAh laboratory test cells. We report bene…

Thermoelectric Properties of Homologous Compounds in the ZnO–In 2 O 3 System

Homologous compounds of (ZnO) m In 2 O 3 (m = integer) with layered structures were synthesized by reaction‐sintering a mixed powder of ZnO and In 2 O 3 at 1823 K for 2 h in air, and their thermoelectric properties, i.e., electrical conductivity, Seebeck coefficient, and thermal conductivity, were measured at 500 to 1…

Reduction of Structural Fe(III) in Smectite by a Pure Culture of Shewanella Putrefaciens Strain MR-1

Abstract Shewanella putrefaciens is a species of metal-reducing bacteria with a versatile respiratory metabolism. This study reports that S. putrefaciens strain MR-1 rapidly reduces Fe(III) within smectite clay minerals. Up to 15% of the structural Fe within ferruginous smectite (sample SWa-1, Source Clays Repository…

The Impact of Corrosion on the Oil and Gas Industry

Summary The impact of corrosion on the oil industry has been viewed in terms of its effect on both capital and operational expenditures (CAPEX and OPEX) and health, safety, and the environment (HSE). To fight against the high cost and the impact of corrosion within the oil industry, an overview of topical research and…

Field tuning of thermally activated magnetic quantum tunnelling in Mn 12 − Ac molecules

Zero-field–cooled magnetization, magnetic relaxation, and a.c. susceptibility measurements have been performed on a Mn 12 -Ac oriented powdered sample as a function of temperature, field, and orientation. Magnetization jumps and susceptibility peaks have been observed about magnetic-field values B n = nB 1 , where B 1…

Nanocrystalline FeNdB permanent magnets with enhanced remanence

Isotropic nanocrystalline exchange coupled FeNdB magnets with enhanced remanence were produced using the melt spinning procedure. Starting from nearly single phase Fe14Nd2B magnets, the content of additional α-Fe in composite magnets was stepwise increased up to 40 vol % by reducing the Nd and B content. The maximum r…

Preparation of Silica from Rice Husks

Preliminary leaching of rice husks with a solution of hydrochloric acid before their combustion at 600°C is shown to be required to obtain relatively pure silica (∼99.5%) with a high specific surface area (∼260 m 2 /g) that is maintained even after heating at 800°C. Transmission electron microscopy observations indica…

Nonlocal and Nonequilibrium Heat Conduction in the Vicinity of Nanoparticles

Heat transfer around nanometer-scale particles plays an important role in a number of contemporary technologies such as nanofabrication and diagnosis. The prevailing method for modeling thermal phenomena involving nanoparticles is based on the Fourier heat conduction theory. This work questions the applicability of th…

VALENCE: a program for calculating bond valences

The DOS program VALENCE is designed to calculate bond valences from bond lengths and vice versa. It can also calculate bond-valence sums and average bond lengths, and can determine bond-valence parameters from the bonding environments of different cations.

Thermomechanical properties in a thin film of shape memory polymer of polyurethane series

The thermomechanical properties of a thin film of shape memory polymer of polyurethane series were investigated experimentally. Based on the experimental results, the dynamic mechanical properties, cyclic deformation properties at high temperature, thermomechanical cycling properties, creep and stress relaxation are d…