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81.
Nonlinear magnetotransport of two-dimensional electrons in square antidot lattices prepared on the basis of selectively doped GaAs/AlAs heterostructures with the period that is much less than the electron mean free path in the initial GaAs quantum wells but is much larger than their Fermi wavelength has been studied. It has been shown that the character of the nonlinear transport of the two-dimensional electrons in the lateral lattices under study changes from classical to quantum with the decrease in the antidot radius. It has been found that the quantum lifetime increases in the magnetic field corresponding to the condition of equality of the cyclotron diameter of two-dimensional electrons and the antidot lattice period. 相似文献
82.
Mariusz P. Mitoraj Goran V. Janjić Vesna B. Medaković Dušan Ž. Veljković Artur Michalak Snežana D. Zarić Miloš K. Milčić 《Journal of computational chemistry》2015,36(3):171-180
The water/aromatic parallel alignment interactions are interactions where the water molecule or one of its O? H bonds is parallel to the aromatic ring plane. The calculated energies of the interactions are significant, up to ΔECCSD(T)(limit) = ?2.45 kcal mol?1 at large horizontal displacement, out of benzene ring and CH bond region. These interactions are stronger than CH···O water/benzene interactions, but weaker than OH···π interactions. To investigate the nature of water/aromatic parallel alignment interactions, energy decomposition methods, symmetry‐adapted perturbation theory, and extended transition state‐natural orbitals for chemical valence (NOCV), were used. The calculations have shown that, for the complexes at large horizontal displacements, major contribution to interaction energy comes from electrostatic interactions between monomers, and for the complexes at small horizontal displacements, dispersion interactions are dominant binding force. The NOCV‐based analysis has shown that in structures with strong interaction energies charge transfer of the type π → σ*(O? H) between the monomers also exists. © 2014 Wiley Periodicals, Inc. 相似文献
83.
Kanie K Matsubara M Zeng X Liu F Ungar G Nakamura H Muramatsu A 《Journal of the American Chemical Society》2012,134(2):808-811
The first simple-cubic liquid crystal was obtained by coating monodisperse Au nanoparticles (NPs) with a thick corona of amino-substituted organic dendrons. This unusual structure was determined by grazing-incidence diffraction and electron density reconstruction and explained by analyzing the radial density profile of the corona. Another novel structure is proposed for the phase preceding the cubic one: a hexagonal superlattice composed of alternating dense and sparse strings of Au NPs. 相似文献
84.
HJ Kim F Liu JH Ryu SK Kang X Zeng G Ungar JK Lee WC Zin M Lee 《Journal of the American Chemical Society》2012,134(33):13871-13880
Bent-shaped rigid-core molecules with flexible chiral dendrons grafted to the outer side of the bend were synthesized and characterized by circular dichroism, differential scanning calorimetry, X-ray scatterings, and transmission electron microscopy in solution and the solid state. The bent aromatic rods based on hepta- and nonaphenylene with nitrile groups at both ends self-assemble into well-ordered hollow tubular structures in aqueous solution, while the bent rod based on heptaphenylene without nitrile groups showed no apparent aggregations in aqueous solution. In the solid state, the rigid-flexible molecules based on heptaphenylene rod without the nitrile group self-assemble into a 2D oblique columnar structure with the columnar cross-section containing two interlocked molecules. Remarkably, the rigid flexible molecules based on hepta-, nona-, and undecaphenylene with nitrile groups self-assemble into a hexagonal columnar structure with weak 3D order. A model of vesicular channel structure is proposed based on small- and wide-angle X-ray diffraction on oriented fibers, density measurement, reconstruction and simulation of electron density maps, and molecular dynamics simulation. In contrast to the hollow tubular structure found in solution, in the solid both the outside and the interior of the columns are filled by the pendant aliphatic coils. Filling of the interior of these vesicular channels is made possible by some bent rod molecules turning their obtuse apex inward. One in 7, 2 in 8, and 4 in 10 molecules are thus inverted in a column slice in compounds with hepta-, nona-, and undecaphenylene cores, respectively. These are new examples of vesicular double-segregated columnar structures recently discovered in some dendrons. 相似文献
85.
A new reader for radiation dose measurements using RADFET (pMOSFET) dosemeters has been developed. The threshold voltage (VT) of the pMOSFETs is measured using a “one-point” method that determines VT as the gate voltage for a given drain current. Using VT, the absorbed dose, which is directly proportional to the threshold voltage shift, is calculated. The reader is based on a low cost 8-bit PIC 18F4520 microcontroller (MCU), and works independently of a personal computer, uses a touch screen and stores the data in microcontroller memory. Good agreement in threshold voltage values, obtained using a high-quality source-measure unit and the reader, was obtained. In addition, the reader can be used for threshold voltage measurement with other types of MOSFETs, especially in long duration experiments, as well as for the real-time measurements in radiotherapy, either as an autonomous system or integrated in a larger monitoring configuration. 相似文献
86.
Jovana Francuz Bojana Srećo Mirjana Popsavin Goran Benedeković Vladimir Divjaković Vesna Kojić Gordana Bogdanović Agneš Kapor Velimir Popsavin 《Tetrahedron letters》2012,53(14):1819-1822
Treatment of 7-O-benzoyl-5-O-benzyl derivatives of (+)-goniofufurone or 7-epi-(+)-goniofufurone with titanium(IV) chloride or titanium(IV) bromide gave 7-chloro and 7-bromo-7-deoxy-goniofufurone mimics as the main reaction products along with minor amounts of the corresponding C-7 epimers. An unexpected cyclized product, benzoxepane 8 was isolated in some cases. 相似文献
87.
Angela Šurca Vuk Boris Orel Goran Dražič 《Journal of Solid State Electrochemistry》2001,5(7-8):437-449
In this paper we generalize the IR spectroscopic properties of M3+VO4 (M=Fe, In) orthovanadate and Fe2V4O13 films. The films were prepared using the sol-gel synthesis route from M3+ nitrates and vanadium oxoisopropoxide. The vibrational bands in the IR absorbance spectra of the films are classified in
terms of terminal V-O stretching (1050–880 cm–1), bridging V-O...Fe and V...O...Fe stretching (880–550 cm–1), mixed V-O-V deformations and Fe-O stretching (<550 cm–1) modes. Ex situ IR spectra of films were measured after consecutive charging/discharging to various intercalation coefficients x and correlated to the current peaks in the cyclic voltammetry curves measured in 1 M LiClO4/propylene carbonate electrolyte. We classified the ex situ IR spectra of charged/discharged films according to their vibrational
band changes. The results reveal that, for small values of the intercalation coefficient, crystalline FeVO4, InVO4 and Fe2V4O13 films exhibit a simultaneous decrease in the intensity of all IR bands while the band frequencies remain unaffected. For
the higher intercalation levels, IR mode frequencies are shifted, signaling the presence of reduced vanadium. Further charging
leads to an amorphization of the film structure, which was established from the similarity of the IR spectra of charged films
with those of amorphous films prepared at lower annealing temperatures. The results confirm that ex situ IR spectroelectrochemical
measurement is an effective way to assess the structural changes in films with different levels of intercalation.
Electronic Publication 相似文献
88.
Changlong Chen Dr. Robert Kieffer Dr. Helgard Ebert Dr. Marko Prehm Dr. Rui-bin Zhang Dr. Xiangbing Zeng Prof. Dr. Feng Liu Prof. Dr. Goran Ungar Prof. Dr. Carsten Tschierske 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(7):2747-2751
The single gyroid phase as well as the alternating double network gyroid, composed of two alternating single gyroid networks, hold a significant place in ordered nanoscale morphologies for their potential applications as photonic crystals, metamaterials and templates for porous ceramics and metals. Here, we report the first alternating network cubic liquid crystals. They form through self-assembly of X-shaped polyphiles, where glycerol-capped terphenyl rods lie on the gyroid surface while semiperfluorinated and aliphatic side-chains fill their respective separate channel networks. This new self-assembly mode can be considered as a two-color symmetry-broken double gyroid morphology, providing a tailored way to fabricate novel chiral structures with sub-10 nm periodicities using achiral compounds. 相似文献
89.
The Ramanujan Journal - This paper is a continuation of our previous works where we study maps from $$X_0(N)$$ , $$N\ge 1$$ , into $${\mathbb {P}}^2$$ constructed via modular forms of the same... 相似文献
90.