Materials Literature
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We investigate atomic scale friction between clean graphite surfaces by using molecular dynamics. The simulation reproduces atomic scale stick-slip motion and low frictional coefficient, both of which are observed in experiments using frictional force microscope. It is made clear that the microscopic origin of low fri…
A strong correlation among calculated Nucleus-Independent Chemical Shift (NICS) values, molecular planarity, and the observed two-photon absorption (TPA) values was found for a series of closely matched expanded porphyrins. The expanded porphyrins in question consisted of [26]hexaphyrin, [28]hexaphyrin, rubyrin, ameth…
Using an elastostatic description of crack growth based on the Griffith criterion and the principle of local symmetry, we present a stochastic model describing the propagation of a crack tip in a 2D heterogeneous brittle material. The model ensures the stability of straight cracks and allows for the study of the rough…
The antiferromagnetic - ferromagnetic phase transition in YBaCo2O5.50 and YBaCo2O5.44 cobaltites with different types of oxygen-ion ordering in the [YO0.5/0.44] layers has been studied by neutron powder diffraction. Using the magnetic symmetry arguments in combination with group-theoretical analysis, the crystal and m…
We report the anomalous magnetocaloric behavior in the polycrystalline compound Tb2Ni2Sn. The magnetization measurements show that this compound shows multiple magnetic transitions, which are attributed to the coexistence of ferromagnetic and antiferromagnetic phases at low temperatures. With increase in field and tem…
Magnetite nanoparticles of Fe3O4 were found to assemble into monodisperse hollow Fe3O4 microspheres with tunable diameters ranging from 200 to 400 nm and open pores on the shells in ethylene glycol in the presence of dodecylamine (DDA). The oriented assembly of nanoparticles conferred the individual hollow Fe3O4 micro…
Carbon nanotube thin films have been successfully fabricated by the electrophoretic deposition technique. The supercapacitors built from such thin film electrodes have a very small equivalent series resistance, and a high specific power density over 20 kW kg −1 was thus obtained. More importantly, the supercapacitors…
We report experimental results on amorphization and crystallization dynamics of reversible phase-change (PC) thin-film samples, GeSbTe and GeBiTe, for optical disk data storage. The investigation was conducted with subnanosecond laser pulses using a pump-and-probe configuration. Amorphization of the crystalline films…
A series of new lithium aluminum silicate (LAS) glass systems doped with chromium ion is prepared. The reflectance and transmittance of the glass slabs are recorded. By means of an iteration procedure, the glass refractive index n and the extinction coefficient k and their dispersions are obtained. Across a wide spect…
A method of creating rugate interference filters that have flat-topped reflectance across an extended spectral region is presented. The method applies known relations from the classical coupled wave theory to develop a set of equations that gives the spatial frequency distribution of rugate cycles to achieve constant…
Abstract We report photoluminescence (PL) and PL‐excitation spectroscopy of BN nanotubes (nt‐BN) mixed with some residual hexagonal crystalline (h‐BN) starting material, and of pure h‐BN microcrystalline powder. The nanotube phase exhibits a broad‐band PL near 380 nm, in agreement with a published report of cathodolum…
The sequence of previously found phase transitions in CsHSO 4 at around 60, 122, and 141 °C was carefully examined by using thermo-gravimetric analysis (TGA), mass spectroscopy (MS), differential thermal analysis, ac calorimetry, impedance spectroscopy, and x-ray diffraction (XRD). Our results show evidence that at al…
We have investigated the dielectric response in the terahertz (THz) spectral range of a series of Bi-layered ferroelectrics with Aurivillius structure involving ferroelectric compounds $({\mathrm{Bi}}_{4}{\mathrm{Ti}}_{3}{\mathrm{O}}_{12},\mathrm{Sr}{\mathrm{Bi}}_{2}{\mathrm{Ta}}_{2}{\mathrm{O}}_{9},\mathrm{Sr}{\mathr…
We presents what we believe to be a new approach to choosing a sequence of monitoring wavelengths for monochromatic monitoring of optical coating production. The new approach is based on a preproduction estimation of expected levels of errors in thickness of layers of a deposited coating. It is demonstrated that the p…
We review new strategies for the development of Gd3+-based T1-relaxation agents and paramagnetic chemical exchange saturation transfer (PARACEST) "sensing" contrast agents (SCAs) designed specifically to detect small molecules or enzymatic activity in living systems. The first class of agents exhibits molecular "sensi…
Abstract An efficient and simple wet chemistry methodology to synthesize iron filled singlewalled carbon nanotubes (Fe‐SWCNT) is presented. The route leads to the formation of long continuous iron cables within the tubes. Partial filling is also observed. The morphology, high filling aspect and the chemical profile of…
5-Nor-Me was prepared by a two-step synthesis. A disappearing polymorph, the yellow form (Y), was observed during synthesis, but pure Y could not be obtained with further purification by crystallization. The other two forms, red (R) and orange (O), were prepared by crystallization from tetrohydrofuran (THF) and absolu…
PEG was grafted onto chitosan regioselectively at the hydroxyl groups with phthaloylchitosan as an intermediate. After the graft reaction, the phthaloyl groups were deprotected to give chitosan-g-PEG copolymers with free amino groups. The chemical structure of the graft copolymers was confirmed by FT-IR, (1)H and (13)…
The magnetic phases of hexagonal perovskites RMnO 3 (R = Ho, Er, Tm, Yb, Sc, Y) are analysed using group theory and the Landau theory of phase transitions. The competition between various magnetic order parameters is discussed in the context of antiferromagnetic interactions. A phenomenological model based on four one…
We report ab initio calculations of the highly nonideal pyrope $({\mathrm{Mg}}_{3}{\mathrm{Al}}_{2}{\mathrm{Si}}_{3}{\mathrm{O}}_{12})$--grossular $({\mathrm{Ca}}_{3}{\mathrm{Al}}_{2}{\mathrm{Si}}_{3}{\mathrm{O}}_{12})$ garnet solid solution. The results highlight the crucial influence of the local environment of indi…