2,975 research outputs found
3,6-Bis(4-chlorophenyl)-N 1,N 4-bis(1-phenylethyl)-1,2,4,5-tetrazine-1,4-dicarboxamide
In the title molecule, C32H28Cl2N6O2, the amide-substituted N atoms of the tetrazine ring deviate from the approximate plane of the four other atoms in the ring by 0.468 (3) and 0.484 (3) Å, forming a boat conformation. The dihedral angle between the two phenyl rings is 67.0 (1)° and that between the two chloro-substituted benzene rings is 73.8 (1)°. Two intramolecular N—H⋯N hydrogen bonds are observed
Differential Harnack inequalities for nonlinear heat equations with potentials under the Ricci flow
We prove several differential Harnack inequalities for positive solutions to
nonlinear backward heat equations with different potentials coupled with the
Ricci flow. We also derive an interpolated Harnack inequality for the nonlinear
heat equation under the -Ricci flow on a closed surface. These new
Harnack inequalities extend the previous differential Harnack inequalities for
linear heat equations with potentials under the Ricci flow.Comment: 17 pages. New explanations added; Final versio
Interpolating between constrained Li-Yau and Chow-Hamilton Harnack inequalities for a nonlinear parabolic equation
We establish a one-parameter family of Harnack inequalities connecting the
constrained trace Li-Yau differential Harnack inequality for a nonlinear
parabolic equation to the constrained trace Chow-Hamilton Harnack inequality
for this nonlinear equation with respect to evolving metrics related to Ricci
flow on a 2-dimensional closed manifold. This result can be regarded as a
nonlinear version of the previous work of Y. Zheng and the author (Arch. Math.
94 (2010), 591-600).Comment: 13 pages; references and explanations adde
Enhancement of Drought Tolerance in Trifoliate Orange by Mycorrhiza: Changes in Root Sucrose and Proline Metabolisms
Sucrose and proline metabolisms are often associated with drought tolerance of plants. This study was conducted to investigate the effects of two arbuscular mycorrhizal fungi (AMF) species (Funneliformis mosseae and Paraglomus occultum) on root biomass, lateral root number, root sucrose and proline metabolisms in trifoliate orange (Poncirus trifoliata) seedlings under well-watered (WW) or drought stress (DS). All the AMF treatments significantly increased root dry weight, taproot length, and the number of lateral roots in 1st, 2nd, and 3rd class under WW and DS. Mycorrhizal seedlings conferred considerably higher fructose and glucose concentrations but lower sucrose accumulation, regardless of soil water status. Under DS, F. mosseae treatment significantly increased root sucrose synthase (SS, degradative direction) and sucrose phosphate synthase (SPS) activity but deceased root acid invertase (AI) and neutral invertase (NI) activity, and P. occultum inoculation markedly increased root AI, NI, SS, and SPS activities. AMF treatments led to a lower proline accumulation in roots, in company with lower activities of Δ1-pyrroline-5-carboxylate synthetase (P5CS), δ-ornithine aminotransferase (OAT), Δ1-pyrroline-5-carboxylate reductase (P5CR), and proline dehydrogenase (ProDH) in roots. It appears that the AM symbiosis induced greater root development and sucrose and proline metabolisms to adapt DS
Modelling travel time distribution and its influence over stochastic vehicle scheduling
Due to the paucity of well-established modelling approaches or well-accepted travel time distributions, the existing travel time models are often assumed to follow certain popular distributions, such as normal or lognormal, which may lead to results deviating from actual ones. This paper proposes a modelling approach for travel times using distribution fitting methods based on the data collected by Automatic Vehicle Location (AVL) systems. By this proposed approach, a compound travel time model can be built, which consists of the best distribution models for the travel times in each period of a day. Applying to stochastic vehicle scheduling, the influence of different travel time models is further studied. Results show that the compound model can fit more precisely to the actual travel times under various traffic situations, whilst the on-time performance of resulting vehicle schedules can be improved. The research findings have also potential benefit for the other research based on travel time models in public transport including timetabling, service planning and reliability measurement
Additive-Controlled Divergent Synthesis of Tetrasubstituted 1,3-Enynes and Alkynylated 3H-Pyrrolo[1,2-a]indol-3-ones via Rhodium Catalysis
Herein, we report the additive-controlled divergent synthesis of tetrasubstituted 1,3-enynes and alkynylated 3H-pyrrolo[1,2-a]indol-3-ones through rhodium-catalyzed C-H alkenylation/DG migration and [3+2] annulation, respectively. This protocol features rare directing group migration in 1,3-diyne-involved C-H activation, excellent regio- and stereoselectivity, excellent monofunctionalization over difunctionalization, broad substrate scope, moderate to high yields, good functional group compatibility, and mild redox-neutral conditions
A van der Waals pn heterojunction with organic/inorganic semiconductors
van der Waals (vdW) heterojunctions formed by two-dimensional (2D) materials
have attracted tremendous attention due to their excellent electrical/optical
properties and device applications. However, current 2D heterojunctions are
largely limited to atomic crystals, and hybrid organic/inorganic structures are
rarely explored. Here, we fabricate hybrid 2D heterostructures with p-type
dioctylbenzothienobenzothiophene (C8-BTBT) and n-type MoS2. We find that
few-layer C8-BTBT molecular crystals can be grown on monolayer MoS2 by vdW
epitaxy, with pristine interface and controllable thickness down to monolayer.
The operation of the C8-BTBT/MoS2 vertical heterojunction devices is highly
tunable by bias and gate voltages between three different regimes: interfacial
recombination, tunneling and blocking. The pn junction shows diode-like
behavior with rectifying ratio up to 105 at the room temperature. Our devices
also exhibit photovoltaic responses with power conversion efficiency of 0.31%
and photoresponsivity of 22mA/W. With wide material combinations, such hybrid
2D structures will offer possibilities for opto-electronic devices that are not
possible from individual constituents.Comment: 16 pages, 4 figure
Rhodium(III)-Catalyzed C–H Alkenylation/Directing Group Migration for the Regio- and Stereoselective Synthesis of Tetrasubstituted Alkenes
An efficient Rh(III)-catalyzed C-H alkenylation/directing group migration cascade between indoles and alkynes for the assembly of tetrasubstituted alkenes is reported. The carbamoyl directing group migrates to the carbon of the alkene moiety of the products through rare Rh-catalyzed C-N bond cleavage after the C-H alkenylation step and thus acts as an internal amidation reagent. This protocol shows broad substrate scope, excellent regio/stereoselectivity, and good to excellent yields
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