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121.
We investigated the growth characteristics and properties of GaAsBi layers grown by atmospheric-pressure metal–organic vapor-phase epitaxy on different GaAs substrate orientations. The surface morphology of GaAsBi alloys was investigated by means of scanning electron microscopy. The structural and optical properties of the alloys were examined using high-resolution X-ray diffraction (HRXRD) and photoreflectance spectroscopy, respectively. HRXRD results show that the GaAsBi growth rate was significantly lower on (1 1 5)A than on (0 0 1), (1 1 1)A and (1 1 4)A GaAs. The highest Bi content was obtained for GaAsBi layers grown on (1 1 5)A GaAs substrates. 相似文献
122.
The Fermi-liquid theory formulated by Landau is a basic paradigm of the behavior of an interacting many-body system. We present a new application of this theory to calculate the "Landau force" on a macroscopic object. We show that immersing a pendulum in a Fermi liquid can increase its oscillation frequency, and evidence of this has been observed in mixtures of (3)He and (4)He. 相似文献
123.
A previously proposed five parameter phenomenological screened shell model for the lattice dynamics of cubic metals is applied to compute the phonon frequencies of copper in the off-symmetry directions. The theoretical results are compared with the experimental findings for the first time. It has been pointed out that a model which gives excellent results in the symmetry directions may not necessarily reproduce similar results in the off-symmetry directions. 相似文献
124.
Strong Exchange Coupling in a Trimetallic Radical‐Bridged Cobalt(II)‐Hexaazatrinaphthylene Complex 下载免费PDF全文
Dr. Jani O. Moilanen Dr. Nicholas F. Chilton Dr. Benjamin M. Day Dr. Thomas Pugh Prof. Dr. Richard A. Layfield 《Angewandte Chemie (International ed. in English)》2016,55(18):5521-5525
Reducing hexaazatrinaphthylene (HAN) with potassium in the presence of 18‐c‐6 produces [{K(18‐c‐6)}HAN], which contains the S=1/2 radical [HAN].?. The [HAN].? radical can be transferred to the cobalt(II) amide [Co{N(SiMe3)2}2], forming [K(18‐c‐6)][(HAN){Co(N′′)2}3]; magnetic measurements on this compound reveal an S=4 spin system with strong cobalt–ligand antiferromagnetic exchange and J≈?290 cm?1 (?2 J formalism). In contrast, the CoII centres in the unreduced analogue [(HAN){Co(N′′)2}3] are weakly coupled (J≈?4.4 cm?1). The finding that [HAN].? can be synthesized as a stable salt and transferred to cobalt introduces potential new routes to magnetic materials based on strongly coupled, triangular HAN building blocks. 相似文献
125.
Straightedge-and-compass construction problems are well known for different reasons. One of them is the difficulty to prove that a problem is not constructible: it took about two millennia to prove that it is not possible in general to cut an angle into three equal parts by using only straightedge and compass. Today, such proofs rely on algebraic tools difficult to apprehend by high school student. On the other hand, the technique of problem reduction is often used in theory of computation to prove other kinds of impossibility. In this paper, we adapt the notion of reduction to geometric constructions in order to have geometric proofs for unconstructibility based on a set of problems known to be unconstructible. Geometric reductions can also be used with constructible problems: in this case, besides having constructibility, the reduction also yields a construction. To make the things concrete, we focus this study to a corpus of triangle location problems proposed by William Wernick in the eighties. 相似文献
126.
In this study, we compared the mineralization rates of three selected (14)C-labeled hydrocarbon compounds, octacosane, toluene, and naphthalene, with the presence of the corresponding functional genes (alkB, xylE, nahAc) in a large number of soil samples representing different types of soil and petroleum hydrocarbon contamination. Functional genes were enumerated by the replicate limited dilution (RLD) polymerase chain reaction (PCR) technique. RLD-PCR was further compared to real-time PCR measurements for nahAc and xylE for some samples. At a heating oil-contaminated site, octacosane mineralization rates were higher (on average 0.0015 day(-1)) when compared to aerobic naphthalene and toluene mineralization (on average 0.00003 and 0.0007 day(-1)). The corresponding gene abundances measured by RLD-PCR were on average 0.95, 0.3, and 0.13 x 10(3) gene copies g(-1) soil for alkB, nahAc, and xylE, respectively. At a site contaminated with gasoline, the situation was the opposite: Toluene mineralization was the highest (on average 0.0031 day(-1)), and only xylE genes could be detected (on average 0.13 x 10(3) gene copies g(-1) soil by RLD-PCR). XylE and nahAc gene abundances were correlated with the (14)C-toluene and naphthalene mineralization activities, respectively, in samples from aerobic layers. AlkB gene abundances were not correlated with the octacosane mineralization. Real-time PCR was a more sensitive method than RLD-PCR by a factor of 1,200 for nahAc and 300 for xylE. In conclusion, functional gene abundances seemed to reflect the type of the contamination. With optimized assays, the gene abundances can be used to assess bioremediation efficacy. 相似文献
127.
We revisit the boundedness of Hankel and Toeplitz operators acting on the Hardy space H
1 and give a new proof of the old result stating that the Hankel operator H
a
is bounded if and only if a has bounded logarithmic mean oscillation. We also establish a sufficient and necessary condition for H
a
to be compact on H
1. The Fredholm properties of Toeplitz operators on H
1 are studied for symbols in a Banach algebra similar to C + H
∞ under mild additional conditions caused by the differences in the boundedness of Toeplitz operators acting on H
1 and H
2.
The first author was partially supported by the European Commission IHP Network “Harmonic Analysis and Related Problems” (Contract
Number: HPRN-CT-2001-00273-HARP) and by the Greek Research Program “Pythagoras 2” (75% European funds and 25 National funds).
The second author was fully supported by the European Commission IHP Network “Harmonic Analysis and Related Problems” (Contract
Number: HPRN-CT-2001-00273-HARP) while he visited the first author at the University of Crete and later by the Academy of
Finland Project 207048. 相似文献
128.
Back Cover: Strong Exchange Coupling in a Trimetallic Radical‐Bridged Cobalt(II)‐Hexaazatrinaphthylene Complex (Angew. Chem. Int. Ed. 18/2016) 下载免费PDF全文
129.
Jack Brimberg Stefana Janićijević Nenad Mladenović Dragan Urošević 《Optimization Letters》2017,11(6):1123-1135
In this paper we show that the clique partitioning problem can be reformulated in an equivalent form as the maximally diverse grouping problem (MDGP). We then modify a skewed general variable neighborhood search (SGVNS) heuristic that was first developed to solve the MDGP. Similarly as with the MDGP, significant improvements over the state of the art are obtained when SGVNS is tested on large scale instances. This further confirms the usefulness of a combined approach of diversification afforded with skewed VNS and intensification afforded with the local search in general VNS. 相似文献
130.
Tadeusz?Iwaniec Leonid?V.?Kovalev Jani?OnninenEmail author 《Journal of Dynamics and Differential Equations》2011,23(1):185-212
A uniqueness theorem is established for autonomous systems of ODEs, [(x)\dot] = f(x){\dot{x}\,{=}\,f(x)}, where f is a Sobolev vector field with additional geometric structure, such as delta-monotonicity or reduced quasiconformality. Specifically,
through every non-critical point of f there passes a unique integral curve. 相似文献