Materials Literature
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Dense PbTiO 3 ceramics consisting of submicrometer‐sized grains were prepared using the spark‐plasma‐sintering (SPS) method. Hydrothermally prepared PbTiO 3 (0.1 μm) was used as a starting powder. The powder was densified to ≳98% of the theoretical X‐ray density by the SPS process. The average grain size of the spark‐…
The photosensitized oxidations of the olefins, trans- 1,2-dimethoxystilbene (DMOS), trans -stilbene (TS), and trans,trans -1,4-diphenyl-1,3-butadiene (DPB) as well as the amine 2,2,6,6-tetramethylpiperidine (TMP) in mixed surfactant vesicles were investigated. The sensitizer was either a hydrophobic dye, tetraphenylpo…
The rigorous microscopic theory of equilibrium crystal shapes has made enormous progress during the last decade. We review here the main results that have been obtained, both in two and higher dimensions. In particular, we describe how the phenomenological Wulff and Winterbottom constructions can be derived from the m…
Most mesogens formed by banana-shaped molecules exhibit liquid-like smectic phases. Here we present the synthesis and properties of homologous series of derivatives of resorcinol and 2,6-disubstituted pyridine. One of these classes of bent-core molecules displays the nematic phase.
Stable nematic phases are reported for binary mixtures of p-alkylbenzoic acids (nBA; where n = 1,2,3 denotes methyl, ethyl and propyl), p-alkoxybenzoic acids (nOBA, n = 1,2), and p-fluorobenzoic acid, which separately do not exhibit liquid crystalline phases. The mesophase stability increases in equimolar mixtures of…
Rapid densification of a nanometer SiC powder doped with 2.04 wt% Al 4 C 3 and 0.4 wt% B 4 C was conducted by using a nonconventional sintering technique called pulse electric current sintering (PECS). In all experiments, the sintering temperature and applied pressure were kept to be 1600 o C and 47 MPa, respectively,…
Clinotobermorite, Ca 5 Si 6 O 17 ·5H 2 O, is a rare mineral, structurally related to tobermorite 11 A. It is characterized by the presence of structural disorder (evidenced by the diffuseness of the reflections with k odd) which, until now, prevented the determination of its real structure. In this paper, a model for…
A passive cavitation detector (PCD) identifies cavitation events by sensing acoustic emissions generated by the collapse of bubbles. In this work, a dual passive cavitation detector (dual PCD), consisting of a pair of orthogonal confocal receivers, is described for use in shock wave lithotripsy. Cavitation events are…
To obtain a sensitive picture of discharging faults in power cables the PD should be ignited, detected, and located at power frequencies that are comparable to operating conditions at 50 or 60 Hz. In this way, realistic magnitudes in [pC] and reproducible patterns of discharges in a power cable can be obtained. PD mea…
It is demonstrated that Lewis acid doping of polyaniline in the oxidation state of emeraldine can be conveniently monitored by 57 Fe Mössbauer spectroscopy if FeCl 3 is used as the dopant. The spectrum of doped polyaniline consists of two doublets with distinctly different Mössbauer parameters which can be unequivocal…
Conducting nanocomposite samples were prepared combining colloidal ferric oxide particles with conducting polypyrrole. Three composite samples (prepared keeping colloidal content fixed and varying the content of the conducting polypyrrole) and the pure polymer were used in the present investigation. Temperature depend…
High-molar-mass silsesquioxanes (SSQO) based on (3-glycidoxypropyl)trimethoxysilane (GPMS) and (3-methacryloxypropyl)trimethoxysilane (MPMS) were synthesized. The hydrolytic condensation of GPMS was performed using HCOOH (0.1 N) as catalyst, keeping the molar ratio H 2 O/Si = 3. A first step was performed in tetrahydr…
New linear and star structured poly(3,4-ethylenedioxythiophene−didodecyloxybenzenes) (PEBs) have been prepared which exhibit thermochromism and multicolor electrochromism as they are able to produce the three basic colors in the RGB system: red, green, and blue. The star polymer features a conjugated hyperbranched pol…
We have used laser ablation to grow series of ${\mathrm{PbTiO}}_{3}{/\mathrm{B}\mathrm{a}\mathrm{T}\mathrm{i}\mathrm{O}}_{3}$ (PTO/BTO) multilayers with a modulation wavelength \ensuremath{\Lambda} that varies between $50\AA{}<\ensuremath{\Lambda}<360\AA{}.$ Modeling the x-ray-diffraction patterns of the multila…
Atomic sites with multiple substituents are common in minerals, and correct site assignment of substituents in structure refinement is of fundamental importance. Substituents must be assigned to particular sites to fit the observed site scattering and chemical analysis, but the assignments are rarely made with mathema…
The effect of pretreatment of several cis-1,4-polyisoprene containing rubbers on their biodegradability was examined. Tests were carried out with six recently isolated and characterized rubber degrading bacteria belonging to the genera Gordonia (strains Kb2, Kd2 and VH2), Mycobacterium, Micromonospora and Pseudomonas.…
A read–write–erase system for micropatterning tungsten oxide films is reported here. The Figure shows blue spots of tungsten bronze formed locally on tungsten oxide film by locally generating a reductant close to the film. The process utilizes the scanning electrochemical microscope (SECM) not only to inject charge bu…
Abstract Structural and physical properties of the Cu salts of a series of π-acceptors N,N′-dicyanobenzoquinonediimines (DCNQIs) are described. The most notable feature of this system is that 3d electrons in Cu interact with pπ electrons in DCNQI near the Fermi level. This unique feature has provided a lot of interest…
Crystalline cadmium sulfide is a semiconductor for which the wurtzite and zinc blende structures are energetically almost degenerate. Due to quantum-confinement effects, it is possible to tune the optical properties of finite cadmium sulfide clusters by varying their size. Here, we report results of a theoretical stud…
Si 3 N 4 ceramics were fabricated by tape casting of a raw‐powder slurry seeded with three types of rodlike β‐Si 3 N 4 particles. The effects of seed size on the microstructure and mechanical properties of the sintered specimens were investigated. All the seeded and tape‐cast silicon nitrides presented an anisotropic…