Mathematical simulation for effects of flow control devices in two-strand slab tundish

Fluid flows in a two-strand tundish for slab continuous casting were performed with mathematical simulation methods. The molten steel flow velocity fields in the tundish with a turbulence inhibitor, dam, and weir were numerically calculated. Simulation results showed that the tundish with a turbulence inhibitor with no opened holes has similar flow characteristics to the tundish with dam and weir. These results are essential to optimizing the turbulence inhi bitor, dam and weir parameters for slab continuous casting tundish

Topological quantum phase transition in an extended Kitaev spin model

We study the quantum phase transition between Abelian and non-Abelian phases in an extended Kitaev spin model on the honeycomb lattice, where the periodic boundary condition is applied by placing the lattice on a torus. Our analytical results show that this spin model exhibits a continuous quantum phase transition. Also, we reveal the relationship between bipartite entanglement and the ground-state energy. Our approach directly shows that both the entanglement and the ground-state energy can be used to characterize the topological quantum phase transition in the extended Kitaev spin model.Comment: 9 Pages, 4 figure

Molecular cloning, structural analysis and expression of a zinc binding protein in cotton

The full-length zinc-binding protein (ZnBP) gene was cloned from a normalized cDNA library constructed from a cotton mutant (Xiangmian-18) during the gland-forming stage. The clone was sequenced and analysed. BLASTP analysis showed that the deduced amino acid sequence of ZnBP in Xiangmian-18 is similar to that in Arabidopsis thaliana (GenBank accession no. EFH46337.1) with an overall similarity of 77%. The cDNA insert comprises 654 base pairs (bp) and 217 amino acid residues. Its molecular weight is 24.6 kDa, and the theoretical pI is 9.33. The cotton ZnBP gene was cloned from the gDNA from Xiangmian-18 leaves. After sequencing the two fragments, a 1731 bp cotton ZnBP gene with three introns was identified. Using pET-28a(+) as a prokaryotic expression vector, the gene was expressed in Escherichia coli BL21(DE3). The conditions for achieving optimal ZnBP expression were 37°C, IPTG 1 mmol/L, 8 h and a shaker speed of 150 rpm. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis confirmed the correct expression of the protein. pCAMBIA2300-35S-OCS was used as a eukaryotic expression vector. The recombinant plasmid pCAMBIA2300-ZnBP was used to transform competent Agrobacterium GV3101 by the freeze-thaw method. Then, A. thaliana plants were transformed by the floral dipping method. Transformed plants were grown to maturity in a growth chamber. After screening on kanamycin-resistant half-strength Murashige and Skoog plates and polymerase chain reaction (PCR) analysis, two transgenic plant strains were obtained. Northern blot analysis showed that ZnBP expression was higher in homozygous plants than in wild-type plants. The differences between the phenotypes of homozygous and wild-type plants indicate that the ZnBP gene affects the growth and development of A. thaliana. The results of prokaryotic expression of ZnBP and overexpression of the ZnBP gene in A. thaliana improve our understanding of the function of this gene. Future studies should investigate the molecular mechanisms involved in gland morphogenesis in cotton.Key words: Gossypium hirsutum, pigment gland, zinc binding protein, prokaryotic expression, overexpression

Long-term lidar observations of the gravity wave activity near the mesopause at Arecibo

Using 11-year-long K Doppler lidar observations of temperature profiles in the mesosphere and lower thermosphere (MLT) between 85 and 100&thinsp;km, conducted at the Arecibo Observatory, Puerto Rico (18.35∘&thinsp;N, 66.75∘&thinsp;W), seasonal variations of mean temperature, the squared Brunt–Väisälä frequency, N2, and the gravity wave potential energy (GWPE) are estimated in a composite year. The following unique features are obtained. (1) The mean temperature structure shows similar characteristics to an earlier report based on a smaller dataset. (2) Temperature inversion layers (TILs) occur at 94–96&thinsp;km in spring, at ∼92&thinsp;km in summer, and at ∼91&thinsp;km in early autumn. (3) The first complete range-resolved climatology of GWPE derived from temperature data in the tropical MLT exhibits an altitude-dependent combination of annual oscillation (AO) and semiannual oscillation (SAO). The maximum occurs in spring and the minimum in summer, and a second maximum is in autumn and a second minimum in winter. (4) The GWPE per unit volume reduces below ∼97&thinsp;km altitude in all seasons. The reduction of GWPE is significant at and below the TILs but becomes faint above; this provides strong support for the mechanism that the formation of upper mesospheric TILs is mainly due to the reduction of GWPE. The climatology of GWPE shows an indeed pronounced altitudinal and temporal correlation with the wind field in the tropical mesopause region published in the literature. This suggests the GW activity in the tropical mesopause region should be manifested mainly by the filtering effect of the critical level of the local background wind and the energy conversion due to local dynamical instability.</p

Unsupervised multi-modal style transfer for cardiac MR segmentation

In this work, we present a fully automatic method to segment cardiac structures from late-gadolinium enhanced (LGE) images without using labelled LGE data for training, but instead by transferring the anatomical knowledge and features learned on annotated balanced steady-state free precession (bSSFP) images, which are easier to acquire. Our framework mainly consists of two neural networks: a multi-modal image translation network for style transfer and a cascaded segmentation network for image segmentation. The multi-modal image translation network generates realistic and diverse synthetic LGE images conditioned on a single annotated bSSFP image, forming a synthetic LGE training set. This set is then utilized to fine-tune the segmentation network pre-trained on labelled bSSFP images, achieving the goal of unsupervised LGE image segmentation. In particular, the proposed cascaded segmentation network is able to produce accurate segmentation by taking both shape prior and image appearance into account, achieving an average Dice score of 0.92 for the left ventricle, 0.83 for the myocardium, and 0.88 for the right ventricle on the test set

Possible itinerant excitations and quantum spin state transitions in the effective spin-1/2 triangular-lattice antiferromagnet Na2_2BaCo(PO4_4)2_2

The most fascinating feature of certain two-dimensional (2D) gapless quantum spin liquid (QSL) is that their spinon excitations behave like the fermionic carriers of a paramagnetic metal. The spinon Fermi surface is then expected to produce a linear increase of the thermal conductivity with temperature that should manifest via a residual value ($\kappa_0/T$) in the zero-temperature limit. However, this linear in T behavior has been reported for very few QSL candidates. Here, we studied the ultralow-temperature thermal conductivity of an effective spin-1/2 triangular QSL candidate Na$_2$BaCo(PO$_4$)$_2$, which has an antiferromagnetic order at very low temperature ($T_N \sim$ 148 mK), and observed a finite $\kappa_0/T$ extrapolated from the data above $T_N$. Moreover, while approaching zero temperature, it exhibits series of quantum spin state transitions with applied field along the $c$ axis. These observations indicate that Na$_2$BaCo(PO$_4$)$_2$ possibly behaves as a gapless QSL with itinerant spin excitations above $T_N$ and its strong quantum spin fluctuations persist below $T_N$.Comment: 24 pages, 5 figures, with Supplementary Informatio

Investigation to the deep center related properties of low temperature grown InPBi with Hall and photoluminescence

InP1-xBix epilayers with bismuth (Bi) concentration x= 1.0% were grown on InP by gas source molecular beam epitaxy (GS-MBE) at low temperature (LT). Bi incorporation decreased the intrinsic free electron concentration of low temperature grown InP indicated by hall analysis. It is concluded that deep level center was introduced by Bi. Influence of Si doping on the InP1-xBix films Photoluminescence (PL) was investigated. N-type doping in the InP1-xBix epilayers was found to be effective at PL enhancement. Blue shift of InPBi PL emission wavelength was observed as the Si doping concentration increasing. Two independent peaks were fitted and their temperature dependence behavior was observed to be distinct obviously. Two individual radiative recombination processes were expected to be involved

Investigation of a mesospheric bore event over northern China

A mesospheric bore event was observed using an OH all-sky airglow imager (ASAI) at Xinglong (40.2° N, 117.4° E), in northern China, on the night of 8–9 January 2011. Simultaneous observations by a Doppler meteor radar, a broadband sodium lidar, and TIMED/SABER OH intensity and temperature measurements are used to investigate the characteristics and environment of the bore propagation and the possible relations with the Na density perturbations. The bore propagated from northeast to southwest and divided the sky into bright and dark halves. The calculations show that the bore has an average phase velocity of 68 m s−1. The crests following the bore have a horizontal wavelength of ~ 22 km. These parameters are consistent with the hydraulic jump theory proposed by Dewan and Picard, as well as the previous bore reports. Simultaneous wind measurements from the Doppler meteor radar at Shisanling (40.3° N, 116.2° E) and temperature data from SABER on board the TIMED satellite are used to characterize the propagating environment of the bore. The result shows that a thermal-Doppler duct exists near the OH layer that supports the horizontal propagation of the bore. Simultaneous Na lidar observations at Yanqing (40.4° N, 116.0° E) suggest that there is a downward displacement of Na density during the passage of the mesospheric bore event.Q. Li, J. Xu, J. Yue, X. Liu, W. Yuan, B. Ning, S. Guan, and J. P. Younge