Materials Literature
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The utilization of surface-attached gold nanoparticles as templates for generating Pt-group particles displaying near-optimal surface-enhanced Raman scattering (SERS) characteristics is described. Essentially epitaxial transition metal coatings down to the monolayer level can be prepared, most readily by the spontaneo…
The morphology of calcium carbonate can be tuned by using aqueous double-hydrophilic block copolymer (DHBC)–surfactant mixtures in a chemical synthesis. Calcite hollow spheres (see Figure) and vaterite discs were obtained at different concentrations of sodium dodecylsulfate (SDS) in a DHBC–SDS system. In contrast, pin…
Collagen-like peptides of the type (Pro-Pro-Gly)(10) fold into stable triple helices. An electron-withdrawing substituent at the H(gamma)(3) ring position of the second proline residue stabilizes these triple helices. The aim of this study was to reveal the structural and energetic origins of this effect. The approach…
Tellurium nanotubes with well-controlled structures (see Figure) are obtained via concentration depletion at the surfaces of seeds. The lengths of these inorganic nanotubes can be varied by adjusting the growth time (see cover), and the outer diameters of the tubes can be controlled by changing the initial concentrati…
Unusual two-dimensional ZnS nanosheets with micrometer scale lateral dimensions and flake-like ZnO dendrites (see Figure) can be rapidly generated with high yield (>96 %) by using a simple template method. The molecular precursor ZnS·(NH2CH2CH2NH2)0.5, which shows a strong ultraviolet emission band centered at 380 nm…
Lasers based on colloidal semiconductor nanostructures can benefit from the remarkable spectral coverage afforded through the quantum confinement effect. The first observation of lasing for colloidal CdSe/ZnS quantum rods in solution using a cylindrical microcavity is reported here (see also inside front cover). Lasin…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSubphthalocyanines: Singular Nonplanar Aromatic CompoundsSynthesis, Reactivity, and Physical PropertiesChristian G. Claessens, David González-Rodríguez, and Tomás TorresView Author Information Departamento de Química Orgánica (C−I), Facultad de Ciencias, Universidad Autónoma…
Phenylacetaldehyde (PhA) has been observed as a by-product in H2O2 metalloporphyrin catalytic oxidation of styrene. We have found that the mechanism of these oxidations depends on the relative amount of the carboxylic acid that is used as co-catalyst. With an excess of the organic acid less PhA is formed due to the in…
Abstract Loss on ignition (LOI) is one of the selected chemical parameters for characterizing the quality of pulverized fuel ashes (PFA). However, this parameter does not represent the unburned carbon in ashes because of the presence of several other compounds which also decompose on heating. In order to evaluate the…
In this letter we report the application of barium–strontium–titanate (BST) thin film oxides as the dielectric layer in radio-frequency-microelectromechanical system (rf-MEMS) capacitive switches. BST thin films deposited at ambient temperature by off-axis sputtering have been employed for application in rf-MEMS switc…
A full color display with its spectra covering the entire visible color range using a single polymer is presented here. Different concentrations of poly(2,6-[4-phenylquinoline]) and poly(2,6-[p-phenylene]-4-phenylquinoline) were incorporated into silica gels via the sol–gel technique. At high concentrations, the conju…
The equilibrium phase diagram of the nickel-manganese system is determined between 500 and 850 °C, in the composition range between 25 and 70 at. % Ni. A combination of electron probe microanalysis, x-ray diffraction, and optical microscopy was employed to analyze 47 samples that were annealed anywhere from three to s…
We consider a static theory of dislocations with moment stress in an anisotropic or isotropic elastoplastic material as a T (3) gauge theory. We obtain Yang-Mills-type field equations which express the force and the moment equilibrium. Additionally, we discuss several constitutive laws between the dislocation density…
Polycrystalline boron carbide (B4C) thin films have been prepared by a pulsed ion-beam evaporation technique without heating substrates or annealing samples. Here, we clearly demonstrate the possibility of preparing B4C thin films for electronic device applications.
Layer-by-layer self-assembly of hexanethiol stabilized gold nanoclusters by a series of alkanedithiol coupling agents [HS(CH2)nSH, n = 6, 8, 9, 12] onto SiO2/Si substrates with micron- and nanometre-scale Au electrodes is investigated by electron transport and XPS measurements. The self-assembly process for each layer…
Selective chemical functionalisation of 2,4,6-trinitrotoluene to a surface enhanced resonance Raman active species for sensitive detection.
A simple method was developed for magnetic hardening melt-spun Sm(Co,Fe,Cu,Zr)z alloys. The as-spun ribbons reached a coercivity of 2.8 T only by slow cooling from 850 to 400 °C, without the standard solid solution and isothermal aging treatments which are required for a bulk precipitation hardened 2:17 SmCo alloy. A…
We report on an enhanced thermoelectric figure of merit ZT=σS2T/λ (where σ is electrical conductivity, S is thermopower, T is absolute temperature, and λ is thermal conductivity) for PbTe/PbSe0.20Te0.80 superlattices (SLs) and PbTe doping SLs due to a reduction of the thermal conductivity λ parallel to the layer plane…
Continuous-wave measurements of the shear elastic constants of bcc Fe–Ga solid solutions show that the constant C44 is independent of the gallium composition while the constant 12(C11–C12) decreases linearly and extrapolates to zero at 26 at. % Ga. This result indicates that the Fe–Ga solid solution is inhomogeneous a…
Recent theoretical studies have concluded that the low formation enthalpies of intrinsic donor defects should preclude achievement of p-type conductivity in undoped ZnO grown in thermal equilibrium with a molecular oxygen reservoir. This letter demonstrates that reactive sputtering can produce intrinsic p-type ZnO, co…