Width-tuned magnetic order oscillation on zigzag edges of honeycomb nanoribbons

Quantum confinement and interference often generate exotic properties in nanostructures. One recent highlight is the experimental indication of a magnetic phase transition in zigzag-edged graphene nanoribbons at the critical ribbon width of about 7 nm [G. Z. Magda et al., Nature \textbf{514}, 608 (2014)]. Here we show theoretically that with further increase in the ribbon width, the magnetic correlation of the two edges can exhibit an intriguing oscillatory behavior between antiferromagnetic and ferromagnetic, driven by acquiring the positive coherence between the two edges to lower the free energy. The oscillation effect is readily tunable in applied magnetic fields. These novel properties suggest new experimental manifestation of the edge magnetic orders in graphene nanoribbons, and enhance the hopes of graphene-like spintronic nanodevices functioning at room temperature.Comment: 22 pages, 9 figure

Stormwater Quality Characteristics and Reuse Analysis of Different Underlying Surfaces at Wanzhou North Station

In response to the water shortage in Wanzhou North Station (WNS), the authors investigated the stormwater quality characteristics with different underlying surfaces of WNS and carried out stormwater reuse analysis in conjunction with the InfoWorks ICM model. The results show that during heavy, torrential, and moderate rainfall, the road stormwater runoff has the highest concentrations of pollutants, with an average EMC (event mean concentration) value of 206 mg/L for COD. For the square runoff, the average EMC values of COD, SS, TN, and TP are 108 mg/L, 395 mg/L, 2.113 mg/L, and 0.128 mg/L, in comparison, the average EMC values of the corresponding indexes for the roof runoff are 65 mg/L, 212 mg/L, 1.449 mg/L, and 0.086 mg/L, respectively, demonstrating their potential for reuse. The R2 (coefficient of determination) of SS and COD in both roof and square runoff are greater than 0.85, with a good correlation, indicating that SS removal is the key to stormwater purification. InfoWorks ICM analysis shows that the recyclable volume of rainwater from WNS in 2018 is 29,410 m3 , accounting for 61.8% of the total annual rainfall. This study is expected to provide an ideal reference for the stormwater management of public buildings in mountainous areas

6-Chloro-N 4,N 4-dimethyl­pyrimidine-2,4-diamine

The asymmetric unit of the title compound, C6H9ClN4, contains four independent mol­ecules (A, B, C and D). Their main difference is the torsion angles, ranging from 1.6 (5) to 5.9 (5)°, between the methyl group and the pyrimidine plane. A pair of inter­molecular N—H⋯N hydrogen bonds link mol­ecules A and C into a twisted dimer with a dihedral angle of 32.9 (1)° between the two pyrimidine rings, creating an R 2 2(8) motif. In the packing, each two mol­ecules of B, C and D form centrosymmetric dimers through two inter­molecular N—H⋯N hydrogen bonds, locally creating R 2 2(8) motifs. The dimers of C and D are alternately bridged by A into an infinite zigzag strip, locally creating two different R 2 2(8) motifs with dihedral angles of 32.9 (1) and 63.4 (1)° between the pyrimidine rings. Finally, these strips together with the dimers of B associate into a complicated three-dimensional framework

Investor attention and stock returns under negative shocks: an empirical analysis based on “Dragon and Tiger” list in China

Using the “Dragon and Tiger” list, we construct a clean indicator that directly measures investor attention, empirically test the effect of investor attention on stock return under negative shocks and whether the effect is affected by the bull or bear market, the industry, firm size, age and state ownership, institutional shareholder holding percentage. The results show that i) an increase in investor attention negatively predicts stock returns when cumulative daily return of a stock listed on “Dragon and Tiger” list on listing day is negative; ii) Investor attention is negatively correlated with stock returns when the stock entered in “Dragon and Tiger” list experienced current cumulative monthly return is negative; iii) Investor attention is negatively correlated with stock returns when monthly cumulative net purchase amount of top 10 institution to the stock listed in “Dragon and Tiger” list is negative; iv) Investor attention is negatively correlated with stock returns when the stock listed in “Dragon and Tiger” list, the ratio of monthly cumulative trading amount of the top 10 institutional traders to total trading amount of the secondary market is in the bottom 30 percentile. These findings not only contribute to the academic research about the relationship between investor attention and stock return, but also provide some guidance to the financial regulatory agencies as to the capital market stability

Loss-difference-induced localization in a non-Hermitian honeycomb photonic lattice

Non-Hermitian systems with complex-valued energy spectra provide an extraordinary platform for manipulating unconventional dynamics of light. Here, we demonstrate the localization of light in an instantaneously reconfigurable non-Hermitian honeycomb photonic lattice that is established in a coherently-prepared atomic system. One set of the sublattices is optically modulated to introduce the absorptive difference between neighboring lattice sites, where the Dirac points in reciprocal space are extended into dispersionless local flat bands. When these local flat bands are broad enough due to larger loss difference, the incident beam is effectively localized at one set of the lattices with weaker absorption, namely, the commonly seen power exchange between adjacent channels in photonic lattices is effectively prohibited. The current work unlocks a new capability from non-Hermitian two-dimensional photonic lattices and provides an alternative route for engineering tunable local flat bands in photonic structures

Loop-mediated isothermal amplification for detection of porcine circovirus type 2

<p>Abstract</p> <p>Background</p> <p>Porcine circovirus type 2 (PCV2) is the primary causative agent of the emerging swine disease known as postweaning multisystemic wasting syndrome (PMWS). Nowadays, polymerase chain reaction (PCR) is still the most widespread technique in pathogen detection. Loop-mediated isothermal amplification (LAMP), a novel nucleic acid amplification method developed in 2000, will possibly replace PCR in the field of detection. To establish a LAMP method for rapid detection of PCV2, two pairs of primers were designed specially from the open reading frame 2 (ORF2) sequences of PCV2. A LAMP method for rapid detection of PCV2 was established. To compare with PCR, sensitivity and specificity of LAMP were evaluated using the optimized reaction system. The LAMP products could be determined by agarose gel electrophoresis or adding SYBR Green I dye.</p> <p>Results</p> <p>The amplification of LAMP could be obtained at 63°C for 60 min. The detection limit was nearly 1 copy of DNA plasmid, more sensitive than PCR. There was no cross-reaction with porcine circovirus type 1 (PCV1), porcine pseudorabies virus (PRV) and porcine parvovirus (PPV) under the same conditions.</p> <p>Conclusions</p> <p>LAMP is an useful rapid detection method with high sensitivity and specificity for PCV2.</p