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91.
N. V. Sopinskii V. S. Khomchenko O. S. Litvin A. K. Savin N. A. Semenenko A. A. Evtukh V. P. Sobolevskii G. P. Ol’khovik 《Technical Physics》2011,56(11):1665-1669
The properties of low-refractive-index carbon films obtained by close-spaced vapor transport at graphite sublimation are studied.
The optical properties of the films are investigated by monochromatic multiple-angle ellipsometry, and their morphology is
examined by AFM. It is found that the films have a columnar structure with a background surface roughness of about 1 nm. In
addition, the surface of the film contains islands up to 50 nm in height with a footprint of ≈200 nm. A low-refractive-index
carbon film deposited by close-spaced vapor transport on silicon tips is found to decrease the field emission threshold and
drastically raise the current. 相似文献
92.
By analyzing high-speed video of the fruit fly, we discover a swimminglike mode of forward flight characterized by paddling wing motions. We develop a new aerodynamic analysis procedure to show that these insects generate drag-based thrust by slicing their wings forward at low angle of attack and pushing backwards at a higher angle. Reduced-order models and simulations reveal that the law for flight speed is determined by these wing motions but is insensitive to material properties of the fluid. Thus, paddling is as effective in air as in water and represents a common strategy for propulsion through aquatic and aerial environments. 相似文献
93.
Attila Tanyi 《Acta Analytica》2014,29(3):331-348
The article begins with Jonathan Dancy’s attempt to refute the Humean Theory of Motivation. It first spells out Dancy’s argument for his alternative position, the view he labels ‘Pure Cognitivism’, according to which what motivate are always beliefs, never desires. The article next argues that Dancy’s argument for his position is flawed. On the one hand, it is not true that desire always comes with motivation in the agent; on the other, even if this was the case, it would still not follow that desire is identical with the state of being motivated. When this negative work is done, the article turns to some positive, albeit admittedly tentative remarks about what sort of cognitivist theory of motivation one should endorse. The aim at this point is not to present a brand new theory, but rather to sketch an alternative that stems from what Dancy himself says and is in line with many of his endorsed commitments in other areas. In this way, by moving beyond Pure Cognitivism, the paper sketches a different, but still ‘Dancyesque’ theory of motivation. 相似文献
94.
Attila Nagy 《Semigroup Forum》2014,89(2):475-478
A semigroup S is called a weakly commutative semigroup if, for every a,b∈S, there is a positive integer n such that (ab) n ∈Sa∩bS. A semigroup S is called archimedean if, for every a,b∈S, there are positive integers m and n such that a n ∈SbS and b m ∈SaS. It is known that every weakly commutative semigroup is a semilattice of weakly commutative archimedean semigroups. A semigroup S is called a weakly separative semigroup if, for every a,b∈S, the assumption a 2=ab=b 2 implies a=b. In this paper we show that a weakly commutative semigroup is weakly separative if and only if its archimedean components are weakly cancellative. This result is a generalization of Theorem 4.16 of Clifford and Preston (The Algebraic Theory of Semigroups, Am. Math. Soc., Providence, 1961). 相似文献
95.
Richard P. Anstee Christina Koch Miguel Raggi Attila Sali 《Graphs and Combinatorics》2014,30(6):1325-1349
A simple matrix is a (0,1)-matrix with no repeated columns. For a (0,1)-matrix F, we say that a (0,1)-matrix A has F as a configuration if there is a submatrix of A which is a row and column permutation of F (trace is the set system version of a configuration). Let \({\|A\|}\) denote the number of columns of A. We define \({{\rm forb}(m, F) = {\rm max}\{\|A\| \,:\, A}\) is m-rowed simple matrix and has no configuration F. We extend this to a family \({\mathcal{F} = \{F_1, F_2, \ldots , F_t\}}\) and define \({{\rm forb}(m, \mathcal{F}) = {\rm max}\{\|A\| \,:\, A}\) is m-rowed simple matrix and has no configuration \({F \in \mathcal{F}\}}\) . We consider products of matrices. Given an m 1 × n 1 matrix A and an m 2 × n 2 matrix B, we define the product A × B as the (m 1 + m 2) × n 1 n 2 matrix whose columns consist of all possible combinations obtained from placing a column of A on top of a column of B. Let I k denote the k × k identity matrix, let \({I_k^{c}}\) denote the (0,1)-complement of I k and let T k denote the k × k upper triangular (0,1)-matrix with a 1 in position i, j if and only if i ≤ j. We show forb(m, {I 2 × I 2, T 2 × T 2}) is \({\Theta(m^{3/2})}\) while obtaining a linear bound when forbidding all 2-fold products of all 2 × 2 (0,1)-simple matrices. For two matrices F, P, where P is m-rowed, let \({f(F, P) = {\rm max}_{A} \{\|A\| \,:\,A}\) is m-rowed submatrix of P with no configuration F}. We establish f(I 2 × I 2, I m/2 × I m/2) is \({\Theta(m^{3/2})}\) whereas f(I 2 × T 2, I m/2 × T m/2) and f(T 2 × T 2, T m/2 × T m/2) are both \({\Theta(m)}\) . Additional results are obtained. One of the results requires extensive use of a computer program. We use the results on patterns due to Marcus and Tardos and generalizations due to Klazar and Marcus, Balogh, Bollobás and Morris. 相似文献
96.
O. N. Nadtoka O. V. Yaroshchuk T. V. Bednaya L. A. Ol’khovik V. G. Syromyatnikov 《Polymer Science Series A》2010,52(3):261-271
Polymethacrylates with side azo fragments containing various end substituents and spacers are synthesized and characterized.
Spatial ordering of azo fragments in the series of the synthesized azo polymers under the action of polarized excitation light
is studied by the methods of null ellipsometry and polarization spectroscopy. Two types of anisotropy development during photoirradiation
are found. In homologs with strong acceptor substituents of azo fragments, biaxial orientational structure can be observed;
as the radiation dose is increased, this structure is transformed into a uniaxial structure with a negative order parameter
and with an axis parallel to the polarization vector of the excitation light. In this structure, the maximum degree of orientational
order is achieved in polymers with high concentrations of azo fragments. In homologs with donor substituents of azo fragments,
the initial stages of irradiation likewise lead to the development of biaxial orientation; later, this orientation is transformed
into an isotropic distribution. The mode of anisotropy development is controlled by the lifetime of photoisomers of azo fragments. 相似文献
97.
A. E. Dolbak B. Z. Ol’shanetskii 《Journal of Experimental and Theoretical Physics》2013,116(6):952-956
The diffusion of silver the (111), (100), and (110) silicon surfaces is studied by Auger electron spectroscopy and low-energy electron diffraction. The mechanisms of diffusion over the (111) and (110) surfaces are revealed, and the temperature dependences of diffusion coefficients are measured. An anisotropy of silver diffusion over the (110) surface is detected. 相似文献
98.
99.
Attila Makó Zsolt Rapi György Keglevich Áron Szöllősy László Drahos László Hegedűs Péter Bakó 《Tetrahedron: Asymmetry》2010,21(8):919-925
The chiral monoaza-15-crown-5 lariat ethers annellated to methyl-4,6-O-benzylidene-α-d-glucopyranoside-1 or mannopyranoside 2 have been applied as phase-transfer catalysts in the epoxidation of substituted chalcones and chalcone analogues with tert-butylhydroperoxide resulting in significant asymmetric induction. It was found that the position of the substituents in the aromatic ring of the chalcone had an influence both on the chemical yields and enantiomeric excesses. The lowest enantioselectivities (62–83% ee) were found in the case of ortho-substituted model compounds. The highest ee values (ee of 83–97%) were obtained in the case of para-substituted models. From among the chalcone analogues, the maximum ee (90–92%) was detected for the model compound having α-tert-butyl- and β-aryl groups. Using glucose-based crown ether 1, formation of the (?)-enantiomer was preferred, while applying mannose-based 2 as the catalyst, the (+)-enantiomer was in excess. 相似文献
100.
Stiedl Bernadett Kovcs-Kiss Dorottya Ludnyi Krisztina Bdis Attila Klebovich Imre Antal Istvn 《Chromatographia》2010,71(1):109-113
Tolperisone HCl is a central muscle relaxant, which was incorporated in a matrix system formulated with poly(ethylene oxide)–PEO, in order to achieve adequate gastric residence time. This tablet presents considerable analytical difficulties in the quantitative determination of the drug, because the PEO matrix causes significant increase of viscosity in the samples. Our purpose was to develop a reproducible sample preparation method, which is adapted from parameters of the in vitro dissolution test and validate an LC-UV analytical method, which allows good recovery of the drug (99.97%). The developed analytical method was suitable for quantitative analysis of tolperisone HCl in matrix tablets. 相似文献