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131.
The Haber mechanism describing the process of hydrogenating nitrobenzene to aniline is shown to be incorrect and a new mechanism is proposed. 相似文献
132.
Direct electron spin resonance (ESR) on a high mobility two-dimensional electron gas in a single AlAs quantum well reveals an electronic g factor of 1.991 at 9.35 GHz and 1.989 at 34 GHz with a minimum linewidth of 7 G. The ESR amplitude and its temperature dependence suggest that the signal originates from the effective magnetic field caused by the spin-orbit interaction and a modulation of the electron wave vector caused by the microwave electric field. This contrasts markedly with conventional ESR that detects through the microwave magnetic field. 相似文献
133.
Kraus S Stern O Lok JG Dietsche W Von Klitzing K Bichler M Schuh D Wegscheider W 《Physical review letters》2002,89(26):266801
We observe the transition from a spin-unpolarized to a polarized nu=2/3 fractional quantum Hall state at low currents (<5 nA), recently described in terms of quantum Hall ferromagnetism, versus density and parallel magnetic field. At larger currents the time and current dependent huge longitudinal resistance (HLR) is always initiated at the transition. Transport in the HLR regime is linear and the amount of current-induced nuclear polarization in the HLR is comparable to the thermal nuclear polarization at approximately 20 mK and 10 T. A current-induced disorder in the nuclear polarization is speculated to cause the enhanced resistance in the HLR regime. 相似文献
134.
Carbon Nanosheets by Morphology‐Retained Carbonization of Two‐Dimensional Assembled Anisotropic Carbon Nanorings
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Dr. Taizo Mori Dr. Hiroyuki Tanaka Dr. Amit Dalui Dr. Nobuhiko Mitoma Dr. Kengo Suzuki Prof. Dr. Mutsuyoshi Matsumoto Dr. Nikhil Aggarwal Prof. Dr. Archita Patnaik Dr. Somobrata Acharya Dr. Lok Kumar Shrestha Dr. Hirotoshi Sakamoto Prof. Dr. Kenichiro Itami Prof. Dr. Katsuhiko Ariga 《Angewandte Chemie (International ed. in English)》2018,57(31):9679-9683
Two‐dimensional (2D) carbon nanomaterials possessing promising physical and chemical properties find applications in high‐performance energy storage devices and catalysts. However, large‐scale fabrication of 2D carbon nanostructures is based on a few specific carbon templates or precursors and poses a formidable challenge. Now a new bottom‐up method for carbon nanosheet fabrication using a newly designed anisotropic carbon nanoring molecule, CPPhen, is presented. CPPhen was self‐assembled at a dynamic air–water interface with a vortex motion to afford molecular nanosheets, which were then carbonized under inert gas flow. Their nanosheet morphologies were retained after carbonization, which has never been seen for low‐molecular weight compounds. Furthermore, adding pyridine as a nitrogen dopant in the self‐assembly step successfully afforded nitrogen‐doped carbon nanosheets containing mainly pyridinic nitrogen species. 相似文献
135.
A synthesis of nicotyrine ( 9 ), and hence formally racemic nicotine, was carried out by elaboration of the 1 : 1 adduct 2 of cycloocta‐1,5‐diene and chlorosulfonyl isocyanate (ClSO2? NCO). Transformation of adduct 2 into carbamate 4 was followed by ozonolysis, tosylation, and NaH treatment, which led to pyrrolidinylpiperidinone 6 . LiAlH4 Reduction, debenzylation, and aromatization yielded 2 . 相似文献
136.
137.
Bellotti R Cafagna F Circella M De Cataldo G De Marzo CN Giglietto N Spinelli P Golden RL Stephens SA Stochaj SJ Webber WR De Pascale MP Morselli A Picozza P Ormes JF Streitmatter RE Massimo Brancaccio F Papini P Piccardi P Spillantini P Basini G Bongiorno F Ricci M Brunetti MT Codino A Grimani C Menichelli M Salvatori I 《Physical review D: Particles and fields》1996,53(1):35-43
138.
This paper presents a method to compute the quasi-conformal parameterization (QCMC) for a multiply-connected 2D domain or surface. QCMC computes a quasi-conformal map from a multiply-connected domain S onto a punctured disk D S associated with a given Beltrami differential. The Beltrami differential, which measures the conformality distortion, is a complex-valued function \(\mu :S\to \mathbb {C}\) with supremum norm strictly less than 1. Every Beltrami differential gives a conformal structure of S. Hence, the conformal module of D S , which are the radii and centers of the inner circles, can be fully determined by μ, up to a Möbius transformation. In this paper, we propose an iterative algorithm to simultaneously search for the conformal module and the optimal quasi-conformal parameterization. The key idea is to minimize the Beltrami energy with the conformal module of the parameter domain incorporated. The optimal solution is our desired quasi-conformal parameterization onto a punctured disk. The parameterization of the multiply-connected domain simplifies numerical computations and has important applications in various fields, such as in computer graphics and vision. Experiments have been carried out on synthetic data together with real multiply-connected Riemann surfaces. Results show that our proposed method can efficiently compute quasi-conformal parameterizations of multiply-connected domains and outperforms other state-of-the-art algorithms. Applications of the proposed parameterization technique have also been explored. 相似文献
139.
A Macrocyclic Ruthenium(III) Complex Inhibits Angiogenesis with Down‐Regulation of Vascular Endothelial Growth Factor Receptor‐2 and Suppresses Tumor Growth In Vivo
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Dr. Wai‐Lun Kwong Dr. Kar‐Yee Lam Dr. Chun‐Nam Lok Dr. Yau‐Tsz Lai Dr. Pui‐Yan Lee Prof. Dr. Chi‐Ming Che 《Angewandte Chemie (International ed. in English)》2016,55(43):13524-13528
A macrocyclic ruthenium(III) complex [RuIII(N2O2)Cl2]Cl ( Ru‐1 ) is reported as an inhibitor of angiogenesis and an anti‐tumor compound. The complex is relatively non‐cytotoxic towards endothelial and cancer cell lines in vitro, but specifically inhibited the processes of angiogenic endothelial cell tube formation and cancer cell invasion. Moreover, compared with known anti‐cancer ruthenium complexes, Ru‐1 is distinct in that it suppressed the expression of vascular endothelial growth factor receptor‐2 (VEGFR2), and the associated downstream signaling that is crucial to tumor angiogenesis. In addition, in vivo studies showed that Ru‐1 inhibited angiogenesis in a zebrafish model and suppressed tumor growth in nude mice bearing cancer xenografts. 相似文献
140.
Brian T. Hastings Charles K. Lok Prof. Dr. Masayuki Wasa 《Angewandte Chemie (International ed. in English)》2016,55(44):13877-13881
Direct Mannich‐type reactions that afford both α‐ and β‐amino esters by the reaction of a broad range of carbonyl compounds and aldimines are disclosed. The transformation is promoted by a sterically frustrated Lewis acid/Brønsted base pair, which is proposed to operate cooperatively: Within the catalyst complex, an enolate is generated that then reacts with a hydrogen‐bond‐activated imine. Noncovalent interactions between reactants and the catalyst provide selectivity and new opportunities for future catalyst design. 相似文献