Observation of forbidden phonons and dark excitons by resonance Raman scattering in few-layer WS2_2

The optical properties of the two-dimensional (2D) crystals are dominated by tightly bound electron-hole pairs (excitons) and lattice vibration modes (phonons). The exciton-phonon interaction is fundamentally important to understand the optical properties of 2D materials and thus help develop emerging 2D crystal based optoelectronic devices. Here, we presented the excitonic resonant Raman scattering (RRS) spectra of few-layer WS$_2$ excited by 11 lasers lines covered all of A, B and C exciton transition energies at different sample temperatures from 4 to 300 K. As a result, we are not only able to probe the forbidden phonon modes unobserved in ordinary Raman scattering, but also can determine the bright and dark state fine structures of 1s A exciton. In particular, we also observed the quantum interference between low-energy discrete phonon and exciton continuum under resonant excitation. Our works pave a way to understand the exciton-phonon coupling and many-body effects in 2D materials.Comment: 14 pages, 11 figure

Active backstepping control of combined projective synchronization among different nonlinear systems

In this article, the authors have studied combination projective synchronization using active backstepping method. The main contribution of this effort is realization of the projective synchronization between two drive systems and one response system. We relax some limitations of previous work, where only combination complete synchronization has been investigated. According to Lyapunov stability theory and active backstepping design method, the corresponding controllers are designed to observe combination projective synchronization among three different classical chaotic systems, i.e. the Lorenz system, Rossler system and € Chen system. The numerical simulation examples verify the effectiveness of the theoretical analysis. Combination projective synchronization has stronger anti-attack ability and antitranslated ability than the normal projective synchronization scheme realized by one drive and one response system in secure communication

Ethyl 2-(3-chloro-2-pyridyl)-5-oxopyrazolidine-3-carboxylate

In the mol­ecule of the title compound, C11H12ClN3O3, the five membered ring adopts an envelope conformation. In the crystal structure, inter­molecular N—H⋯O hydrogen bonds link the mol­ecules into centrosymmetric dimers

Ethyl 3-bromo-1-(3-chloro­pyridin-2-yl)-1H-pyrazole-5-carboxyl­ate

The title compound, C11H9BrClN3O2, is an inter­mediate in the synthesis of Rynaxypyre, a new insecticidal anthranilic diamide used as a potent and selective ryanodine receptor activator. The dihedral angle between the aromatic ring planes is 78.7 (2)°

A fast pruned‐extreme learning machine for classification problem

Agency for Science, Technology and Research (A*STAR) Science and Engineering Research Counci

(2,4-Dihydroxy­benzyl­idene)dimethyl­ammonium dichloro­phosphinate

In the title compound, C9H12NO2 +·Cl2PO2 −, the mol­ecular skeleton of the cation is nearly planar with an r.m.s. deviation of 0.0336 Å. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds link cations and anions into chains running along [10]

A Novel Completely Local Repairable Code Algorithm Based on Erasure Code

Hadoop Distributed File System (HDFS) is widely used in massive data storage. Because of the disadvantage of the multi-copy strategy, the hardware expansion of HDFS cannot keep up with the continuous volume of big data. Now, the traditional data replication strategy has been gradually replaced by Erasure Code due to its smaller redundancy rate and storage overhead. However, compared with replicas, Erasure Code needs to read a certain amount of data blocks during the process of data recovery, resulting in a large amount of overhead for I/O and network. Based on the Reed-Solomon (RS) algorithm, we propose a novel Completely Local Repairable Code (CLRC) algorithm. By grouping RS coded blocks and generating local check blocks, CLRC algorithm can optimize the locality of the RS algorithm, which can reduce the cost of data recovery. Evaluations show that the CLRC algorithm can reduce the bandwidth and I/O consumption during the process of data recovery when a single block is damaged. What\u27s more, the cost of decoding time is only 59% of the RS algorithm

1-Cyano-N-(2,4,5-trichloro­phen­yl)cyclo­propane-1-carboxamide

In the title compound, C11H7Cl3N3O, the dihedral angle between the benzene and cyclo­propane rings is 85.8 (2)°. In the crystal, mol­ecules are linked by C—H⋯O inter­actions, generating C(5) chains propagating in the a-axis direction