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41.
Occhiuto I De Luca G Villari V Romeo A Micali N Pasternack RF Scolaro LM 《Chemical communications (Cambridge, England)》2011,47(21):6045-6047
Chirality is rapidly induced in a fractal aggregate of the porphyrin t-CuPagg by addition of α-helical poly-glutamate. These results demonstrate a facile transfer of chirality via noncovalent interactions to preformed supramolecular assemblies grown in the absence of a chiral template. 相似文献
42.
The thermal decomposition of some mixed uranyl complexes with Schiff bases and DMSO, EtOH or (Ph)3PO as neutral ligand, were investigated and the corresponding activation energy, E*a, and enthalpy of dissociation, ΔHd, values were calculated.
The results obtained indicate that for the same neutral ligand, the thermal stability of the uranyl complexes is influenced by the Schiff base used; for the same Schiff base, the presence of (Ph)3PO results in a greater thermal stability of the mixed complexes than when the other two neutral ligands are present. 相似文献
43.
Amendola V Rizzi GA Polizzi S Meneghetti M 《The journal of physical chemistry. B》2005,109(49):23125-23128
Gold nanoparticles are synthesized by laser ablation of a gold plate in toluene. The nanoparticles do not show their characteristic surface plasmon absorption (SPA) and are found to be included in a graphitic matrix. The absence of this absorption is found to derive from the presence of the matrix which prevents the growth of large nanoparticles and covers them, suppressing the SPA according to the Mie model for core@shell particles. It is possible to recover the nanoparticle SPA by oxidizing the carbon matrix, obtaining, therefore, some control on the activity of this absorption. 相似文献
44.
R. Ficarra M. L. Calabrò S. Tommasini D. Costantino M. Carulli S. Melardi M. R. Di Bella F. Casuscelli R. Romeo P. Ficarra 《Chromatographia》1996,43(7-8):365-368
Summary A high-performance liquid chromatographic method is reported for the resolution of the enantiomers of a series of fused -lactams (2,7-diaza-3-oxo[3.3.0]octan-6-ones) with probable anti-HIV and anticancer activity. Resolution was achieved on a Chiralcel® OD column, cellulose tris-(3,5-dimethylphenyl carbamate) adsorbed on macroporous silica gel; mixtures ofn-hexane and isopropyl alcohol in different proportions were used as the mobile phase. The analysis was studied at different temperatures. 相似文献
45.
The main topic consists of enhancing the geometrical and positioning accuracy of the machine tools with numerical control.
Currently, in order to minimize the errors met during the vertical motions of the moving elements in the structure of a machine
tool, various systems are used that are relatively complex and whose adjustments are difficult to do. This work is presenting
a balancing–compensation system of the elements moving vertically that includes three invention patents; it has a simple structure
that is easily adaptable to various types of machine tools. The newness element of the balancing-compensation system is represented
by the pressure regulator being used, whose operation principle and design is described into detail. The related results have
been reified in increasing by approximately 10 times the geometrical accuracy and, by default, the positioning accuracy of
the element moving in a vertical plane. 相似文献
46.
For group III-nitrides with wurtzite structure the presence of fixed polarization interface charges yields new challenges in order to understand and control Schottky barrier heights, band offsets and 2D confinement in heterostructure FETs. In this short review experimental results obtained by in situ photoemission spectroscopy on MBE AlGaN/GaN heterostructures grown on 6H–SiC are discussed, with emphasis on the presence and interplay of surface electronic states. Schrödinger–Poisson calculations are performed to get the complete band scheme at the selected heterojunctions. Results on the polarity dependence of Pt/GaN Schottky barrier values from the literature are also discussed. 相似文献
47.
F. Romeo 《Journal of sound and vibration》2003,268(3):601-615
The problem of minimizing transmitted vibrations through finitely long periodic structures is addressed. Bi-coupled periodic element properties and arrangement are tailored to localize the response around the excitation source within any assigned frequency range. Bi-dimensional analytical maps of the single unit free-wave propagation domains (stop, pass and complex domains) provide the optimal choice of the cell properties and ordering. Moreover, the amount of vibration suppression along the periodic structure is also controlled as it can be described through iso-attenuation curves representing the contour plot of the real part of the propagation constants. Applications to both undamped and damped beams resting on elastic supports are illustrated. The response of the periodic structures to harmonic excitations is expressed through the wave vector method taking into account the effects of wave reflection due to changes in the cell properties along the structure and boundary conditions. Such computational schemes enables one to overcome numerical difficulties arising in the transfer matrix formulation for structures with a large number of periodic units. 相似文献
48.
49.
Paola Benzi Elena Bottizzo Chiara Demaria Nicoletta Rizzi 《Journal of Chemical Sciences》2007,119(6):631-635
YBa2Cu3Ox (Y-123) and Bi2Sr2Ca1Cu2Ox (Bi-2212) films on various substrates have been prepared by Metal-Organic Deposition starting from different metallorganic
fluorine-free compounds and using a very simple instrumentation. The processing conditions include a rapid pyrolysis step
in air and an annealing step in oxygen for Y-123 and in air for Bi-2212. The films obtained have been characterized by X-ray
diffraction (XRD) and the formation of a superconducting phase of Y-123 or Bi-2212 was confirmed measuring the critical temperature
(T
c) with Ac-susceptibility and resistive measurements. Microstructure and final cationic ratios have been studied by scanning
electron microscopy (SEM) and energy dispersive spectroscopy (EDS). 相似文献
50.