Materials Literature
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Field emission has been measured from a series of tetrahedrally bonded amorphous carbon (ta-C) films produced by the filtered cathodic vacuum arc. The threshold field and current densities achievable have been studied as a function of their sp3 content and of nitrogen incorporation. Typical undoped ta-C films are foun…
New “112” phases, LnBaCo2O5.4, with an ordered oxygen deficient perovskite structure, derived from the YBaFeCuO5-type were studied for Ln=Eu, Gd. The appearance of giant negative magnetoresistance in this structural type is demonstrated. Resistance ratio R0/R7 T reaches at least 10 at 10 K, i.e., is significantly larg…
An anomalous negative temperature dependence of electrical resistivity has been observed in $({\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{V}}_{x}{)}_{3}\mathrm{Al}$ alloys with V compositions up to $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.35$. In particular, the Heusler-type ${\mathrm{Fe}}_{2}\mathrm{VAl}$…
This paper presents a new modelling of positive-discharge development, based on new simplifying assumptions. It presents these assumptions, which are deduced from the existing theoretical models and concern mainly the coupling between the leader corona and the corona region. This model has been validated through the c…
Three-component composites consisting of polypropylene (PP) matrix, poly(vinyl butyral) (PVB) modifier, and mica filler at various ratios of matrix to modifies and a constant mica content (30 wt %) were prepared by using two different kinds of PVB, viz., PVB and PVB-P. By correlating with the morphology, the dynamic m…
Sulfur prevulcanization of natural rubber latex was conducted at 60, 70, 80, and 90°C for different periods. The extent of crosslinking was assessed. Tensile properties, water absorption, leaching, and stress-relaxation characteristics of the films were also evaluated. The volume fraction of rubber (Vr), which is a me…
The melting and crystallization behavior and phase morphology of poly(3-hydroxybutyrate) (PHB) and poly(DL-lactide)-co-poly(ethylene glycol) (PELA) blends were studied by DSC, SEM, and polarizing optical microscopy. The melting temperatures of PHB in the blends showed a slight shift, and the melting enthalpy of the bl…
A new crystalline form and a solvate of glibenclamide were prepared and characterized by hot-stage microscopy, DSC, IR, scanning electron microscope, X-ray powder diffraction and dissolution studies. From I, III and the solvate which melt at 174.4, 153.2 and 109.3 degrees C, were obtained by crystallization. Significa…
Synthesized poly(ester)urea-urethanes with 14C-labeled toluene diisocyanate or 14C-labeled chain extender ethylene diamine were incubated with cholesterol esterase in a phosphate buffer solution at 37 degrees C. A number of biodegradation products, generated at the level of 2.8 micrograms/cm2 of polymer surface area,…
The aim of this study was to evaluate the degradation and foreign-body reaction of poly(DL-lactide-epsilon-caprolactone) (PLA85CL50) bars. This specific biomaterial is used for the construction of nerve guides, which can be used in the reconstruction of short nerve gaps. Subcutaneously implanted PLA85CL50 bars were ha…
The in vivo and in vitro degradation of low-molecular-weight poly(L-lactide), poly(L/D-lactide), and poly (L/DL-lactide) rods was investigated. The low-molecular-weight fast-degrading materials were used to accelerate the degradation process and make the test conditions more critical. In the in vivo study the rods wer…
The objective of the research was to obtain insights into the behavior of microorganisms under feast/famine conditions as often occur in wastewater treatment processes. The response of microorganisms to such conditions is the accumulation of storage polymers like poly(beta-hydroxybutyrate). The research was performed…
Paperback. The porphyrins are a class of naturally-occurring macrocycles and are ubiquitous in our world. As such, they have been called the Pigments of Life. This auspicious designation reflects their importance in numerous biological functions. Indeed, life as we understand it relies on the full range of biological…
We have investigated the influence of surface treatment on the memory angle θm in chevron FLC-cells. Surface anisotropy with different azimuthal anchoring energies was produced either by illumination or by rubbing of a PVA layer containing an azo dye. Due to the low pretilt angle (θp <2°), we suppose that the measured…
Abstract Silberfarbene, spröde Einkristalle von Cs 1,34 Rb 0,66 RbAu 7 und Cs 1,60 Rb 0,40 RbAu 7 wurden durch Umsetzungen von CsN 3 , RbN 3 und Goldschwamm bei 903 K erhalten. Die Strukturen wurden aus Röntgen‐Einkristall‐Diffraktometerdaten bestimmt: Cs 1,34 Rb 0,66 RbAu 7 , Raumgruppe Cmmm , Z = 2, a = 5,657(1) Å,…
An optical method for investigating the dynamics in free-standing films of ferroelectric liquid crystals in the range 10 to 105 Hz by means of optical reflectivity is presented. The experimental results were obtained in the linear-response regime applying electric a. c. fields of strengths less than 16 V cm 1. By meas…
The seminal theory of singular surfaces propounded by Hadamard and Thomas is examined within the context of the dynamics of a solid-liquid interface. It is shown that most of the hypotheses upon which Clapeyron’s equation is based can be weakened and two generalized versions of it are derived: with and without curvatu…
We consider the statics and dynamics of N identical magnetic dipoles, with inertia, pinned at the corners of a regular polygon with N sides. We show that at equilibrium all dipoles are aligned tangent to the circumscribed circle. We find the normal modes and frequencies for oscillations about equilibrium, and discuss…
The trend in pressurized water reactors (PWR) toward higher burnups, increasing lithium concentrations, and higher coolant temperatures imposes a demand for better fuel cladding corrosion and hydriding properties. There is a lack of reliable and fast in-situ techniques to investigate zirconium alloys in high-temperatu…
The effect of irradiation by 300-keV Ar + ions on the properties of electrochemically produced porous silicon is studied at doses of 5×10 14 –1×10 16 cm −2 . Raman scattering and photoluminescence data are used to show that the radiation hardness of porous silicon layers is substantially greater than that of single cr…