Materials Literature
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Parallel-plate Ba0.25Sr0.75TiO3 (BST) varactors with a record high Q factor are fabricated on Si substrate. At 45 GHz the Q factor is about 40, and the tuneability at 25 V is more than 40% in the measured frequency range 0.045–45 GHz. The improvement in the Q factor is achieved by using a thick bottom electrode consis…
We show that the yield strength for Cu with ultrafine grain sizes becomes obviously temperature and strain-rate dependent, in contrast to the temperature/rate insensitive behavior of conventional face-centered-cubic metals. A thermally activated deformation mechanism is operative at room temperature and especially at…
Abstract Poly(vinyl alcohol) (PVA)/clay nanocomposites were synthesized using the solution intercalation method. Na ion‐exchanged clays [Na + –saponite (SPT) and Na + –montmorillonite (MMT)] and alkyl ammonium ion‐exchanged clays (C 12 –MMT and C 12 OOH–MMT) were used for the PVA nanocomposites. From the morphological…
Electrical properties of ZnO nanowires and intramolecular p–n junctions were characterized by I–V measurements. These nanowires were grown embedded in anodic aluminum oxide (AAO) templates by vapor-phase-transport growth method. The nanowires were dense, continuous, and uniform in diameter along the length of the wire…
Basic ideas and results which characterize quantum diffusion of defects in quantum crystals like solid helium as a new phenomenon are presented. Quantum effects in such media lead to a delocalization of point defects (vacancies, impurities etc.) and they turn into quasiparticles of a new type -- defectons, which are c…
The high pressure and high temperature phase diagram of Ta has been studied in a laser-heated diamond-anvil cell (DAC) using x-ray diffraction measurements up to 52 GPa and 3800 K. The melting was observed at nine different pressures, being the melting temperature in good agreement with previous laser-heated DAC exper…
Pure rutile Co-doped TiO2 films were fabricated by the pulsed-laser-deposition technique on silicon substrates from a ceramic target. Under the right fabrication conditions, Co concentration in the films could be almost the same as in the target, and films under various conditions all are ferromagnetic well above room…
Using a first-principles approach based on density-functional theory, we find that a large tetragonal strain can be induced in ${\mathrm{PbTiO}}_{3}$ by application of a negative hydrostatic pressure. The structural parameters and the dielectric and dynamical properties are found to change abruptly near a crossover pr…
We present a quantization scheme for the electromagnetic field interacting with atomic systems in the presence of dispersing and absorbing magnetodielectric media, including left-handed material having negative real part of the refractive index. The theory is applied to the spontaneous decay of a two-level atom at the…
About designing of mathematical model for forecasting of mechanical properties of hypopearlite steels both hot-rolled and strain-heat hardened state.
We calculate the change in the correlation gap of armchair carbon nanotubes with uniaxial elastic strain. We predict that such a stretching will enlarge the correlation gap for all carbon nanotubes by a change that could be as large as several meV per percent of applied strain, in contrast with pure band structure cal…
Perovskite ferroelectric single crystals in the (1−x)BiScO3-xPbTiO3 (BSPT) system were grown using a flux method. The Curie temperature of rhombohedral BSPT(43/57) crystals was found to be about 404 °C, with a rhombohedral–tetragonal phase transition temperature (Tr−t) around 350 °C. The coercive field (Ec) was found…
An early divergence in evolution has resulted in two prokaryotic domains, the Bacteria and the Archaea. Whereas the central metabolic routes of bacteria and eukaryotes are generally well-conserved, variant pathways have developed in Archaea involving several novel enzymes with a distinct control. A spectacular example…
Abstract Given their size, in the single‐digit nanometer range, and the versatility of their functionality, dendrimers and other dendritic macromolecules are poised to make a significant contribution to the rapidly expanding fields of nanoscience and nanotechnology. This highlight focuses on nascent applications of de…
The thermal conductivities of individual single crystalline Si/SiGe superlattice nanowires with diameters of 58 and 83 nm were measured over a temperature range from 20 to 320 K. The observed thermal conductivity shows similar temperature dependence as that of two-dimensional Si/SiGe superlattice films. Comparison wit…
Recent progress in chemical vapour deposition and aerosol synthesis of single-walled carbon nanotubes (SWCNTs) is reviewed with an emphasis on the role of metal nanoparticles in the processes. The effect of the various parameters on SWCNT formation is reported on the basis of published experiments. Evolution of the ca…
We have investigated the formation of 10-50 mm long ``ice spikes'' that sometimes appear on the free surface of water when it solidifies. By freezing water under different conditions, we measured the probability of ice spike formation as a function of: 1) the air temperature in the freezing chamber, 2) air motion in t…
We have isolated the gdp1+ gene from Schizosaccharomyces pombe coding for a membrane protein with guanosine diphosphatase (GDPase) activity, which is highly homologous to Golgi GDPases isolated from other yeast species. The gdp1+ product, Gdp1p, displays both GDPase and uridine diphosphatase (UDPase) activities in vit…
The structures of 3,5-bis[4-(diethylamino)benzylidene]-1-methyl-4-piperidone, C(28)H(37)N(3)O, (I), and 3,5-bis[4-(diethylamino)cinnamylidene]-1-methyl-4-piperidone, C(32)H(41)N(3)O, (II), have been characterized. Because of conjugation between donor and acceptor parts, the central heterocycles (including the carbonyl…
Ozonation of norcarane (1) yielded endo and exo norcarane hydrotrioxides (2a, 2b), as characterized by (1)H and (13)C NMR spectroscopy. Further ozonation of the primary decomposition products of these hydrotrioxides, i.e., 2-norcaranols (3), produced the corresponding isomeric 2-norcaranol hydrotrioxides (4a, 4b), and…