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21.
22.
The nucleation and grain growth of the Ge2Sb2Te5 (GST) thin films were studied using high voltage electron microscope operated at 1250 kV. As a result, we have found that 2 nm-sized nucleus forms as a cluster which atoms are arranged regularly at the stage of nucleation prior to the formation of grains having crystal structure. The high-resolution transmission electron microscopy study and fast-Fourier transformations revealed that coexistence of face-centered-cubic (FCC) and hexagonal structure occurs, and formation of twin defect is found in the hexagonal structure during the grain growth as the annealing temperature is increased. GST grain having the hexagonal structure grow from the surface, and the growth proceeded perpendicular to the [0 0 0 1], namely the path parallel to the (0 0 0 1) plane. Consequently, grain growth to a large-scale result in a lengthened shape. 相似文献
23.
In Homma M and Kim SJ [2], the authors considered two-point codes on a Hermitian curve defined over fields of odd characteristic.
In this paper, we study the geometry of a Hermitian curve over fields of even characteristic and classify the two-point codes
whose minimum distances agree with the designed ones. 相似文献
24.
25.
Self-assembly of a new precursor [Cu(L)](ClO4)2 (1) (L = macrocyclic ligand) with octacyanometalates [M(CN)8]3- (M = Mo, W) produced two-dimensional cyano-bridged Cu(II)-M(V) bimetallic assemblies [Cu(L)]3n[M(CN)8]2n.6nH2O [M = Mo (2), W (3)] with novel honeycomblike structures, characterized by spectroscopic data, single-crystal X-ray diffraction studies, and magnetic measurements. The crystallographic determination reveals that compounds 2 and 3 are isostructural and crystallize in the triclinic system (P). The Cu atom in a distorted octahedral environment experiences a tetragonal elongation of apical nitrogen atoms exhibiting average Cu-Nax lengths of 2.566 Angstroms for 2 and 2.593 Angstroms for 3, which accounts for the Jahn-Teller effect of a Cu(II) ion. The Cu-NC angles are magnetically important, ranging from 135.7 to 159.2 degrees. Three types of L in the crystal lattice are observed, which are dependent on the relative positions of the pendant hydroxyl groups with respect to the CuN4 basal plane. The positions are correlated with hydrogen bonding of OH groups to neighboring atoms. The magnetic data indicate that ferromagnetic and antiferromagnetic interactions between Cu(II) and M(V) through the CN linkage coexist. 相似文献
26.
Hae‐Jeong Lee Christopher L. Soles Da‐Wei Liu Barry J. Bauer Wen‐Li Wu 《Journal of Polymer Science.Polymer Physics》2002,40(19):2170-2177
X‐ray reflectivity has been used to determine the mass uptake of probe molecules in porous thin films supported on thick silicon wafers. The adsorption occurs by capillary condensation when the films are exposed to probe vapor at controlled partial vapor pressures. The probe solvent partial pressure was varied by mixing saturated air and dry air at constant temperature or by changing sample temperature at a constant vapor concentration. Pore size distribution in the films can be calculated from the probe uptake with typical porosimetric approaches such as the application of the Kelvin equation to convert partial pressure into pore size. For illustration, the pore size distribution of three different nanoporous thin films, the primary candidate of ultra‐low‐k interlevel dielectrics in the next generation of integrated circuit chips, was determined with this technique. These samples represent different generations of low‐k dielectrics developed by industry. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2170–2177, 2002 相似文献
27.
Heung-Jin Choi Dong-Hee Lee Yeon Sil Park In-Kyu Lee Young-Chul Kim 《Journal of inclusion phenomena and macrocyclic chemistry》2002,43(1-2):15-18
Octahedrally converging hexadentate macrocyclic receptors 1 and 2, based on L-tartaric acid and furanmoieties, were synthesized andtheir complexation properties studied. In this paper,magnesium ion selectivitiesdetermined by ISE experiments, chiroptical changes observedby circular dichroism(CD) on complexation, and association constants measuredby NMR titration arediscussed. 相似文献
28.
Jeong Gwi-Taek Park Don-Hee Hwang Baik Park Kyungmoon Kim Si-Wouk Woo Je-Chang 《Applied biochemistry and biotechnology》2002,98(1-9):1115-1127
The growth properties of Panax ginseng hairy roots transformed by Agrobacterium rhizogenes were compared between flask and aerated column or stirred bioreactor. In flask cultures, sucrose, initially 30 g/L, was nearly
exhausted after 45 d of culture. The pH of the medium dropped from 5.5 to 4.96 after 10 d, but afterward it gradually increased
to 6.4. After 45 d, hairy roots grew about 16-folds. The growth rate of hairy roots in air-bubble column or stirred bioreactor
cultures was 1.13 (1.11) to 1.23 (1.20) g fresh wt (dry wt)/(g of cells·d), respectively. For both bioreactors, growth was
about three times as high as in the flask cultivation. 相似文献
29.
Tae Oan Ahn Jung Ho Kim Jong Chan Lee Han Mo Jeong Jong-Yoon Park 《Journal of polymer science. Part A, Polymer chemistry》1993,31(2):435-441
A macro-azoinitiator containing polyarylate segment and azo group was prepared by the solution polycondensation of azobiscyanopentanoyl chloride and hydroxy-terminated polyarylates having viscosity-average molecular weights of 6200, 8100, and 12 400. These macro-azoinitiators were used in the radical polymerization of styrene to synthesize polyarylate-polystyrene block copolymers. Thermal properties measured by the differential scanning calorimetry indicated the phase separated morphology of the block copolymers except at low molecular weight of the block constituents. © 1993 John Wiley & Sons, Inc. 相似文献
30.
Photodissociation at 266 nm of protonated synthetic polypeptides containing a tryptophanyl residue was investigated using a homebuilt tandem time-of-flight mass spectrometer equipped with a matrix-assisted laser desorption/ionization source. Efficient photodissociation of the protonated peptides was demonstrated. Most of the intense peaks in the laser-induced tandem mass spectra were sequence ions. Furthermore, sequence ions due to cleavages at all the peptide bonds were observed; this is a feature of the technique that is particularly useful for peptide sequencing. Fragmentations at both ends of the tryptophanyl residue were especially prevalent, which can be useful for location of the tryptophanyl chromophore in a peptide. 相似文献