Materials Literature
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Electron paramagnetic resonance (EPR) has been used to investigate defects in hexagonal boron nitride (BN), polycrystalline cubic BN, BN and BN: C films produced by reactive sputtering. The dominant paramagnetic centre is attributed to the N vacancy. The Epr relaxation parameters have been deduced from the saturation…
The heat capacity for wurtzite-type BN has been determined between 50 and 300 K. The difference from that of zinc blende-type BN, which was also measured between 15 and 300 K, indicates that the interatomic force constants of the wurtzite-type lattice are generally 4% weaker than those of the zinc blende-type one. Thi…
The erosive efficiency of cavitating vortices is well known, although its exact mechanism has not been clarified. In order to bring fundamental information to the subject, a new device called “Cavermod” was designed in which axial collapse of a cavitating vortex is produced. We consider in this paper the design princi…
A new series of 2-(4- n -alkoxyphenyl)-5-(4-methylphenyl)pyridines (CH C H C H NC HOC H, n 1-10) (APMPP), which are teraryl compounds containing a pyridine ring in n 2 m 1 the centre position of the rigid core, was synthesized and the phase transitions of the homologues were studied using DSC measurements, polarizing…
Abstract Sulfur-cured non-reinforced SBR with different amounts of poly-, di- and monosulfidic crosslinks is devulcanized by high power ultrasound irradiation in a continuous process under various processing conditions. Total crosslink density, the proportion of polysulfidic crosslinks, gel fraction, and glass transit…
Abstract An electron microscopy technique which has been used to visualize the crosslinked regions in vulcanized blends of dry rubber has now been applied to films made from natural rubber (NR) latex. The method involves swelling the latex film with styrene, polymerizing the styrene, sectioning the sample and then sta…
Aluminum nitride (AIN) and alumina (Al 2 O 3 ) additives were blended into a high‐purity silicon nitride (Si 3 N 4 ) powder, and optimized processing conditions were applied for promoting a sintering process, which was shown to partly remove the amorphous silica‐rich (SiO 2 ‐rich) remains from grain boundaries. Such a…
Using dielectric spectroscopy in the frequency range 0.1 Hz-1.5 GHz, we investigated the dynamic properties of pentylcianobiphenyl (5CB) confined in porous matrices with randomly oriented, interconnected pores as well as in parallel cylindrical pores with different pores sizes. The confinement has a strong influence o…
As part of a programme to develop high-performance/high-temperature structural resins for aeronautical applications, imide oligomers containing pendent phenylethynyl groups were prepared, characterized, thermally cured and the cured resins evaluated as films, mouldings, adhesives and composites matrices. Initially a d…
Crushed rocks and mine tailings with K‐feldspar, biotite and nepheline as their main K‐bearing minerals were tested as K‐fertilizers in a pot experiment with barley. Equal amounts of K (as analysed by X‐ray fluorescence spectrometry) were added to each treatment before the start of the experiment. Three successive set…
The compounds Na(13)Cd(20)E(7) (E = Pb, Sn) were made in nearly 100% yield by quenching the melts of appropriate mixtures of elements sealed in niobium containers. They crystallize in the cubic space group Im&thremacr;, Z = 4, with a = 15.992(2) and 15.790(4) Å for E = Pb and Sn, respectively. The Cd/E part of the str…
The birch bark cherry, a Chinese tree that also grows in the State of Washington, has a remarkable set of properties. The horizontally peeling bark is semitransparent and very tough, with mechanical properties comparable to those of commercially important films such as Saran or Mylar.
We investigate light propagation through materials with both linear and circular anisotropy and find the relation of the amplitude and polarization transfer functions to the four anisotropic characteristics: linear circular birefringence, and linear and circular dichroism. We determine these four characteristics of an…
Abstract Commercially available Al isopropoxide (Al(OiPr) 3 ) has proved to be an efficient initiator for the bulk polymerization of lactide. The ring‐opening polymerization proceeds through a “coordination‐insertion” mechanism and the selective rupture of the acyl‐oxygen bond of the monomer. Polyester chains are sele…
In recent years a substantial amount of research has been devoted under - standing of anchoring and ordering mechanisms of liquid crystal molecules near solid surfaces. The interaction of a liquid crystalline compound with a solid surface depends on the nature of both the surface and liquid crystal material. The diele…
Potassium dichromate supported on neutral alumina is a heterogeneous catalyst for the liquid phase oxidation of hydrocarbons. The material has been used to catalyse the oxidation of ethylbenzene to acetophenone using air as the consumable oxidant with high selectivity and is truly catalytic in the metal, unlike homoge…
Free‐standing alumina‐13% titania samples were manufactured with a water‐stabilized plasma spray gun to a thickness of ∼5 mm. A thin layer of aluminum was arc sprayed prior to depositing the thick coating and etched away using hydrochloric acid. The so‐obtained free‐standing plate was cut into four‐point‐bend‐test spe…
[H3N(CH2)6NH3]2[H9O4][RhCl6]Cl2, obtained from 1,6-diaminohexane and rhodium trichloride in 12 M hydrochloric acid, has been shown by X-ray crystallography to contain chain-like [H9O4]+ ions in the cavities of a complex organic−inorganic framework built up by 1,6-diammoniohexane, hexachlororhodate(3−), and chloride io…
The occurrence (or not) of a ferroelectric phase transition and the field induced ferroelectric to relaxor states transition has been studied through dielectric susceptibility and pyroelectric current experiments in the x/65/35 PLZT series (x=5 to 12). The results are qualitatively interpreted using random field theor…
Since the 1970s, hygienic improvements have led to a reduction in the level of airborne pollutants in Danish foundries. This mortality study reflects the exposure situation prior to 1970, and the findings may be used as a baseline for future evaluations of the preventive impact of reduced exposure. Mortality data were…