Materials Literature
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X-ray structures of the peripherally crowded porphyrins, (2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphinato) Zn(II)-3MeOH solvate (ZnOETPP·3MeOH) and (2,3,7,8,12,13,17,18-octamethyl-5,10,15,20-tetraphenylporphinato) Zn(II)-pyridine-2HCCl3 (ZnOMTPP·py·2HCCl3) are reported. Both molecules are severely nonpl…
Direct observations using scanning transmission electron microscopy (STEM) of the grain‐boundary chemistry of selectively doped SrTiO 3 and BaTiO 3 show the predominant solute segregation in both systems to be that of acceptors (negative effective charge). Appreciable donor segregation is not observed even at lattice…
One important mechanical property of dental ceramics is fracture toughness, KIC, which represents the serviceability in the oral cavity, such as the resistance to marginal fracture. KIC values of several dental ceramics, natural tooth enamel and industrial ceramics were examined by use of the indentation microfracture…
Summary Direct visual studies of foam flow in etched-glass micromodels containing residual oil demonstrate that foam decays as a result of breakage of pseudoemulsion films. Foam films collapse whenever nearby thin aqueous films separating gas bubbles and oil rupture. Consequently, surfactant formulation for foam insen…
Boron and nitrogen KVV Auger electron spectroscopy (AES) and core level x-ray photoelectron spectroscopy (XPS) features are shown to be conspicuously different for the cubic and hexagonal phases of boron nitride, i.e., cBN and hBN, respectively. The origin and assignments of these features are discussed in terms of th…
Abstract A round robin test organized by the European Federation of Corrosion (EFC) Working Party on Surface Science and the Mechanisms of Corrosion and Protection, supported by the European Community Bureau of References (BCR), and further extended under VAMAS (Versailles Project on Advanced Materials and Standards),…
When blending incompatible polymers in the melt, the resulting morphology is strongly dependent on the interfacial tension. One stage of the mixing process is now used to determine this interfacial tension: in the absence of an overall flow field, extended liquid threads in a liquid matrix exhibit sinusoidal disturban…
Aluminum nitride possesses a unique ability to accommodate oxygen via lattice dissolution to levels exceeding 4 at.%. The mechanism for this large accommodation of oxygen is of technological and scientific interest due to the established delecterious effects of oxygen on the thermal conductivity in this material. When…
A general discussion of the designs and functions of the silk structures spiders use to capture prey has not been attempted since the book of Witt et al (319). Knowledge has increased so greatly in the intervening years that complete coverage is now impossible in a review article. I have cited primarily more recent an…
Anisotropic gels were produced by photopolymerization of an oriented liquid-crystalline (LC) mixture containing LC diacrylates and conventional LC molecules. Gels produced in this way were clear and did not give rise to excess scattering of light. Upon application of an electric field across the gel, the system turned…
Grain growth kinetics and grain‐boundary segregation of 12Ce‐TZP and 2Y‐TZP, containing divalent to pentavalent cationic dopants, were studied. In all cases, normal grain growth follwing the parabolic growth relation was observed at higher temperatures. The mobility of grain boundaries was suppressed by the addition o…
Transient cavitation is a discrete phenomenon that relies on the existence of stabilized nuclei, or pockets of gas within a host fluid, for its genesis. A convenient descriptor for assessing the likelihood of transient cavitation is the threshold pressure, or the minimum acoustic pressure necessary to initiate bubble…
Pseudomonas aeruginosa PAO and 15 other strains of this species synthesized a polyester with 3-hydroxydecanoate as the main constituent (55 to 76 mol%) if the cells were cultivated in the presence of gluconate and if the nitrogen source was exhausted; 3-hydroxyhexanoate, 3-hydroxyoctanoate, and 3-hydroxydodecanoate we…
We demonstrate control of the optical coupling between a pair of planar waveguides by application of voltage to surface-stabilized ferroelectric liquid-crystal films between them. A prototype switch exhibited a response time of 200 μs and a 40:1 switching ratio.
Conducting and transparent thin films of tin oxide were prepared by the laser evaporation of an undoped powder-pressed polycrystalline tin oxide target onto unheated substrates. After characterizing these films, the results reveal that the films are highly oriented and with a grain size ∼0.2 μm. The nearly stoichiomet…
We report the successful fabrication of ZnSe p-n junction light-emitting diodes in which Li and Cl are used as p-type and n-type dopants, respectively.
Photochromism has been studied for irradiated type Ib diamonds which are then annealed above 1500 degrees C. This mainly involves H2 and H3 centres. When the samples are illuminated with light of wavelength shorter than 600 nm, absorption of H2 centres is reduced while that of H3 centres is enhanced. In the dark the p…
Hyperfine fields and electronic structures were calculated by the KKR method to investigate the effects of the X atom on the magnetic properties of Co 2 MnX. The obtained magnetic moments of Co or Mn sites in Co 2 MnX are in good agreement with the experimental ones. Though the obtained hyperfine fields on Co or Mn si…
The magnetic structure of the weak ferromagnet ludlamite, Fe3(PO4)2.4H2O, has been re-examined by both polarized and unpolarized neutron diffraction from single crystal samples of the mineral. The crystal structure has been refined from three dimensional data collected at 20 K, the unit cell being monoclinic, a=10.542…
The structural phase transitions occurring in the chain compounds (CH 3 ) 4 NMnCl 3 (TMMC) and (CH 3 ) 4 NCdCl 3 (TMCC) are studied through X-ray diffraction measurements. In both compounds, the existence of a new high-temperature orientationally disordered phase is established (phase I') with space group P6 3 /mmc an…