Materials Literature
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Abstract Summary: The fragmentation of supports, a key issue for the polymerization of olefins via supported metallocene catalysts, was investigated by laser scanning confocal fluorescence microscopy (LSCFM). Metallocenes were immobilized on silica and on two organic supports, namely polystyrene latex particles and a…
Using the field emission effect of a carbon nanotube (CNT), we characterized a new type of technology for detecting low pressure. The fabricated low pressure sensor is of a triode type, consisting of a cathode (carbon nanotubes field emitter arrays), a grid, and a collector. The gauge described here has a triode confi…
Abstract Star‐shaped poly( L ‐lactide)s (PLAs) bearing variable numbers of secondary hydroxyl groups at linear arms chain‐ends and primary hydroxyl groups directly attached to dipentaerithritol core (DPE) ((HO) 6 − x DPE(PLA‐OH) x , where x = 1–6) were prepared and then analyzed by means of size exclusion chromatograp…
The phonons of single-wall carbon nanotubes are investigated within a generalized bond-charge model. The computed phonon dispersions generally agree with earlier results: two acoustic phonons (longitudinal and rotating), flexure modes at low frequencies, and radius-dependent radial breathing modes. Computation of the…
The sputtering yields of tungsten and tantalum due to low-energy (30–125eV) xenon ion bombardment in a plasma environment are measured both using weight loss and spectroscopic techniques. The yields of both tungsten and tantalum are practically identical and show a reduction of 3 when compared to the molybdenum yield…
Abstract 3D dandelion‐like porous nanostructures and 2D nanowalls of copper phosphate dihydrate built up of thin nanosheets have been synthesized simply by corrosion of a copper foil with aqueous phosphoric acid under mild conditions. The composition of the nanostructures has been confirmed by XRD, ICP‐AES, and Raman…
Abstract This article describes the polyaddition of bifunctional five‐membered cyclic carbonates and diethylenetriamine. The polyaddition proceeded via the selective addition of the primary amino group to the cyclic carbonates to give poly(hydroxyurethane)s bearing a secondary amine structure in the main chain. The re…
Perovskite oxide La 0.825 Sr 0.175 MnO 3 (LSMO) nanowires are synthesized using the anodized alumina oxide template technique and the characterization of the microstructure, magnetic and photoluminescence properties is performed. The as-prepared LSMO nanowires 50 nm in diameter and tens of microns in length exhibit po…
We address in this paper the long debated issue of the possibility of vibrational pumping under Surface Enhanced Raman Scattering (SERS) conditions, both theoretically and experimentally. We revisit with simple theoretical models the mechanisms of vibrational pumping and its relation to heating. This presentation prov…
The formation of singlet oxygen due to the energy transfer from excitons confined in silicon nanocrystals to oxygen molecules is studied using time-resolved photoluminescence spectroscopy. The process of the excitation of oxygen molecules from the ground triplet state to the second excited singlet state is studied at…
Abstract Summary: Octamaleimidophenyl polyhedral oligomeric silsesquioxane (OmipPOSS) was synthesized via the imidization reaction between octaaminophenyl polyhedral oligomeric silsesquioxane (OapPOSS) and maleic anhydride, and it was characterized by means of Fourier transform infrared (FTIR) and NMR spectroscopies.…
The effects of cross-sectional deformation and bending on the electronic structures of single-wall carbon nanotubes (SWNTs) are examined. Upon increasing the deformation, semiconducting SWNTs undergo semiconductor-metal transition, and the conduction band and valence band show asymmetric response to the deformation. T…
Abstract Summary: A scaling exponent to describe the dependence of the hydrodynamic radius as a characteristic length of the molecule on the molecular weight, has been determined for low generation dendrimers with a thiacalixarene core and lysine dendrons. The hydrodynamic radius has been calculated from the diffusion…
Unter Strom: Die strukturellen und elektronischen Eigenschaften von meso-arylsubstituiertem Decaphyrin oder Octaphyrin ändern sich gravierend, wenn eine 1,4-Phenylen-Brücke in die Makrocyclen eingefügt wird. In einem seiner beiden Oxidationszustände zeigt verbrücktes Decaphyrin einen starken diatropen Ringstrom. Röntg…
Einführen einer Ethylendithio-Einheit in einen amphiphilen Makrocyclus mit zwei anellierten Tetrathiafulvalen-Ringen führt zu Organogelen, die in Langmuir-Blodgett-Filmen Nanopunktanordnungen bilden (siehe Bild). Chemische Oxidation des schwefelhaltigen π-Elektronensystems liefert elektrisch leitende Nanopunktstruktur…
The diffusion of water confined in a stack of GM3 ganglioside bilayers is studied by computer simulation. A theoretical analysis of the behavior of the mean square displacement parallel and perpendicular to the bilayer surface is also provided in terms of diffusion equations in a very long time interval, between 2 ps…
A new approach for the detection of DNA using surface enhance resonance Raman scattering (SERRS) is reported. The majority of existing techniques use fluorescence spectroscopy with advanced probe design to provide information on the identity of specific DNA sequences down to single base resolution. A new approach to t…
An analytic interatomic bond-order potential (BOP) is derived that depends explicitly on the group number of the $sp$-valent element. This is achieved by generalizing the previously published BOP for group-IV elements by extrapolating from half-full occupancy using a simple envelope function for the upper bound of the…
In an earlier study, using an SMA-actuated robotic arm, the authors showed that the existing phenomenological models are not able to predict the behavior of the material under certain conditions. There, it was shown that such cases most often occur when the temperature and stress of the SMA wire change simultaneously.…
Abstract Summary: Electrically conducting polypyrrole‐poly(ethylene oxide) (PPy‐PEO) composite nanofibers are fabricated via a two‐step process. First, FeCl 3 ‐containing PEO nanofibers are produced by electrospinning. Second, the PEO‐FeCl 3 electrospun fibers are exposed to pyrrole vapor for the synthesis of polypyrr…