Materials Literature
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Synthesis of optically active natural carotenoids and structurally related compounds. IV. Synthesis of (3 R , 3′ R , 6′ R )‐lutein The synthesis of (3 R , 3′ R , 6′ R )‐lutein ( 19 ) according to the building principle C 25 +C 15 C 40 is reported utilizing ( R )‐4‐hydroxy‐2,6,6‐trimethyl‐2‐cyclohexen‐1‐one ( 4 ) as a…
The subject of gradient-index optics dates from the 1850s. However, only in the last 10 years has it been possible to design lenses, manufacture materials, measure the properties, and fabricate lens elements. The current status of gradient-index optics is reviewed.
The complex dielectric constant ϵ = ϵ′– jϵ″ of single crystals of squaric acid C4H2O4(H2SQ) was examined at around 100 MHz and between 2 and 8 GHz as a function of temperature. In the GHz range the imaginary part ϵ″ can be well described by the beginning of a monodispersive relaxation, whose relaxation frequency slows…
The anomalous photovoltaic effect referred to here is obtained fro crystals without a centre of symmetry. The spatially oscillatory photovoltaic current is investigated and the photovoltaic coefficients kijk for SbSI and ZnS determined. These coefficients are k31 = 4 × 10−8 Acm/W, k32 = 3 × 10−8 Acm/W, and k33 = (2 to…
The synthesis is described of four new cleavable, photosensitive, heterobifunctional cross-linking reagents for use in examining membrane organization: 4'-azidoazobenzene-4oxysuccinimide ester (1), N-[4-(p-azidophenylazo)benzoyl]-3-aminopropyl-N'-oxysuccinimide ester (2), N-[4-(p-azidophenylazo)benzoyl]-6-aminohexyl-N…
Optical materials for the 8 - 13 micron waveband are discussed and a range of high performance infrared telescopes incorporating chalcogenide glass is described.
The valence states of Fe and the charge compensation by oxygen vacancies of Fe57-doped BaTiO3 are studied by the Mössbauer effect and gravimetry as a function of O2 partial pressure. By preparational and analytical effort, it is ensured that the dopant homogeneously substitutes Ti4+ in the BaTiO3 lattice (up to 1.2 mo…
The perovskites Pb(Sc1/2Nb1/2)O3 and Pb(Sc1/2Ta1/2)O3 can be obtained in a disordered state by means of a synthesis at high temperature (1250 to 1500°C). Ordering of the trivalent and pentavalent ions occurs during annealing at lower temperatures. The kinetics of this ordering process are investigated by means of X-ra…
Electro-optical measurements of the electric field along solid insulator/vacuum interfaces have been made to determine the mechanisms associated with fast (ns) insulator flashover. Data showing the temporal and spatial performance of the insulator surface fields prior to and at flashover are presented. The results sho…
By modifying the surface plasma mode on a bare metal surface with an ultrathin film deposited on the metal, we measured the film thickness by attenuated total reflection (ATR). Various factors causing measurement errors are estimated with numerical examples. As a result, for example, it is shown that for some thicknes…
The vibrational averaging theory of Kern and Matcha is extended, at the harmonic level of approximation, to the case where the molecular property under investigation can itself lead indirectly to a perturbation of the vibrational levels of the molecule. It is found that contributions arising from this perturbation can…
The observation of a frequency-dependent conductivity ($\ensuremath{\sigma}$) and dielectric constant ($\ensuremath{\epsilon}$) in Nb${\mathrm{Se}}_{3}$ is reported. In both charge-density-wave phases a strong frequency dependence and huge dielectric constant are observed below 100 MHz, with greatest effects observed…
The heat capacities of LaNi5, α-LaNi5H0.36, and β-LaNi5H6.39 were measured from 5 to 300 °K, and in the case of LaNi5 also from 300 to 350 °K. Various special techniques and unusual circumstances involved in the measurements and calculations are described. A slight enhancement of the heat capacity of β-LaNi5H6.39 was…
While thin films of TiN and TaN are good diffusion barriers in contact structures which use nickel or gold as a top layer, they show poor barrier properties if aluminum is used as a top layer. It is shown in this letter that stable high-temperature contacts on silicon semiconductor devices can be produced by using int…
Optical spectra of the elpasolite hexachloride compounds Cs2NaLnCl6, where Ln represents one of the lanthanide ions, are analyzed with a crystal-field Hamiltonian of Oh symmetry. Crystal-field parameters, Bnm, are found that minimize the rms deviation between calculated and experimental energy levels for Ln=Ce, Pr, Nd…
The complete determination of the crystal structure of solid nitromethane has been obtained from single crystal x-ray diffraction and neutron powder diffraction data. The structure is orthorhombic, space group P212121 with a=5.1832 Å, b=6.2357 Å, c=8.5181 Å at T=4.2 K, and Z=4. Two models were used to describe the the…
Extensive electrical resistivity and Seebeck-coefficient measurements are reported for ${({\mathrm{V}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x})}_{2}{\mathrm{O}}_{3}$ single-crystal alloys in the range $0\ensuremath{\le}x\ensuremath{\le}0.1$. For $0\ensuremath{\le}x\ensuremath{\le}0.005$ a metal-insulator transition is enc…
Theoretical studies of the vibrational excitations of charged solitons in polyacetylene are reported. Two strongly infrared active modes, derived from bulk optical phonons, are associated with these defects and we suggest the presence of a third, as yet unobserved, infrared-active mode in the acoustic phonon regime.
The in situ temperature coefficient of resistance of palladium films in the thickness range 25-370 AA is reported. The Fuchs theoretical curve agrees with experimental alpha versus t curve for a specularity parameter p=0.88. The thickness dependence of the temperature coefficient of resistance gives the bulk mean free…
The effects of oxidation on the electrical conduction of low- and high-density polyethylene (LD-PE and HD-PE) have been studied. It has been found that oxidation enhances the carrier mobility in LD-PE, but lowers that in HD-PE. A qualitative explanation of these opposing effects is given, based on the assumption that…