Materials Literature
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The synthesis of a number of 3d transition metal binary pyrazolates in microcrystalline form, thus suitable for a full XRPD characterization, has been pursued. The crystal and molecular structures of the Fe(pz)3, Co(pz)2, Co(pz)3, and Ni(pz)2 polymers, together with the few congeners reported in the recent literature,…
The grafting of alkanethiol-terminated poly(ethylene glycol) [HS(CH 2 ) 11 (OCH 2 CH 2 ) n −OCH 3; n = 34−56, MW ≈ 2224 Da] onto polycrystalline gold from dilute solutions was investigated by ellipsometry, X-ray photoelectron spectroscopy, infrared reflection−absorption spectroscopy, and in situ second harmonic genera…
Protein interaction with surfaces is one of the most important criteria for the selection of implantable biomaterials as it can mediate further cellular interaction and therefore influence biocompatibility of the surfaces. An ideal biomaterial would adsorb no protein, which is practically impossible to achieve. Here w…
Polyethyene oxide (PEO) oligomers (CH3−(O−CH2CH2)n−, where n = 2, 4, 〈8〉, and 〈12.5〉, and the brackets denote Mn averages) have been attached to Q8M8H silsesquioxanes to form Q8M8PEO(n). The effect of the inorganic interface is to raise the glass transition temperature, Tg, and suppress the crystallization of the PEO…
Chlorophyll a was adsorbed to mesoporous silica (FSM, folded-sheet mesoporous material) to form a chlorophyll-FSM conjugate, in which a nanometer-scale interaction between chlorophyll a molecules resembles a living plant leaf. The mesopores of FSM acted as nanoscale spaces not only for an interaction between chlorophy…
The novel mononuclear PPh4-fac-[FeIII[HB(pz)3](CN)3]*H2O (1) [PPh4+= tetraphenylphosphonium cation; (HB(pz)3)- = hydrotris(1-pyrazolyl)borate] and tetranuclear fac-[[FeIII[HB(pz)3](CN)2(mu-CN)]3FeIII(H2O)3]*6H2O (2) have been prepared and characterized by X-ray diffraction analysis. Crystal data for compound 1: monocl…
Molecular aspects of polymer melt rheology play an extremely strong role in governing the processing−structure−property relations of semicrystalline polymers, the dominant materials in the plastics industry. Recent advances in experimental apparatus and methods have revealed that the dramatic changes in crystallizatio…
We investigate antilocalization due to spin-orbit coupling in ballistic GaAs quantum dots. Antilocalization that is prominent in large dots is suppressed in small dots, as anticipated theoretically. Parallel magnetic fields suppress both antilocalization and also, at larger fields, weak localization, consistent with r…
Software for time-of-flight single crystal diffractometer (SCD) data visualization and analysis was originally written to be run in batch mode on VMS-VAX systems. Modern computers and software tools allow a new level of visualization and user interaction. The Integrated Spectral Analysis Workbench (ISAW) is being exte…
NeXus is an international standard data format intended to reduce the need for redundant software development efforts in the neutron and x-ray scattering communities. As the NeXus standard matures it is starting to be used at laboratories for storing raw data. The Manuel Lujan Jr. Neutron Scattering Center (MLNSC) at…
Organically modified layered silicates (OLS) with high thermal stability are critical for synthesis and processing of polymer layered silicate nanocomposites (PLSN). In the current study, the non-oxidative thermal degradation chemistry of alkyl and aryl quaternary phosphonium-modified montmorillonites (P-MMT) was exam…
A real crystal octahedron is defined as any polyhedron bounded, at least, by some of four pairs of parallel planes being in a standard crystallographic orientation with arbitrary distances between them. All the combinatorially non-equivalent shapes (30 in total) are found and characterized by 2-subordination symbols,…
Low-dose, low-temperature kinematic and dynamical convergent-beam electron diffraction (CBED) patterns from thin organic crystalline films have been used for the measurement of structure-factor amplitudes and phases. Kinematic conditions are identified by the observation of uniform intensity within the CBED discs and…
Dreikernige Kupferkomplexe wurden mit einem in 2,4,6-Position modifizierten 1,3,5-Trihydroxybenzolliganden erhalten (siehe Bild; =Bipyridin, 2-Formylphenolat). Die m-Phenylenverbrückung führt in diesen Komplexen zu ferromagnetischen Wechselwirkungen durch Spinpolarisierung.
We have carried out DC magnetization measurements on spherical glassy carbon exposed to high temperatures and high pressures. The observed magnetic signals clearly depend on the sintering temperature. On the basis of the graphitization temperature (around 1400oC), the behaviour can be classified into three regions: (1…
Ein Triblockcopolymer als Templat und ein Organosiloxan oder ein organisches Additiv ermöglichten die erste Synthese von großporigen (bis zu 9.5 nm), dreidimensionalen, bikontinuierlichen mesoporösen SiO2-Materialien mit Ia3d-Symmetrie bei Raumtemperatur in wässrig-saurem Medium. Gezeigt ist eine Transmissionselektron…
Size-controlled nanocrystalline silicon (nc-Si) has been prepared from a-SiN x /a-Si:H/a-SiN x ('a' standing for amorphous) structures by thermal annealing. Transmission electron microscope analyses show that the lateral size of the nc-Si is controlled by the annealing conditions and the a-Si sublayer thickness. The d…
Einen nahezu kugelförmigen Cluster von etwa 2.5 nm Durchmesser bilden die Silberatome (blau), S2−-Liganden (gelb) und Phosphoratome der PnPr3-Liganden (grün) in [Ag188S94(PnPr3)30] (siehe Bild). Die Phosphanliganden stehen wie die Stacheln eines Igels vom Ag2S-Clusterkern nach außen ab, und das Schwefelteilgitter ist…
Cavities, indentations, and pockets aplenty! By means of self-activated silyl-assisted polyonio substitution (SASAPOS), meso-tetrakis(pentafluorophenyl)porphyrin can be nearly quantitatively converted into the twentyfold positively charged polycation 1, within which 20 counterions are housed. The most drastic steric a…
Polystyrene (PS) combs and dendrigrafts bearing di(hydroxymethyl) group termini at each branch end were used as starting materials for the preparation of branched and hyperbranched polymer structures with ferrocenyl moieties at their periphery. Quantitative acetalization of the 1,3-propanol ends using carboxaldehyde f…