Diverse anisotropy of phonon transport in two-dimensional IV-VI compounds: A comparative study

New classes two-dimensional (2D) materials beyond graphene, including layered and non-layered, and their heterostructures, are currently attracting increasing interest due to their promising applications in nanoelectronics, optoelectronics and clean energy, where thermal transport property is one of the fundamental physical parameters. In this paper, we systematically investigated the phonon transport properties of 2D orthorhombic group IV-VI compounds of $GeS$, $GeSe$, $SnS$ and $SnSe$ by solving the Boltzmann transport equation (BTE) based on first-principles calculations. Despite the similar puckered (hinge-like) structure along the armchair direction as phosphorene, the four monolayer compounds possess diverse anisotropic properties in many aspects, such as phonon group velocity, Young's modulus and lattice thermal conductivity ($\kappa$), etc. Especially, the $\kappa$ along the zigzag and armchair directions of monolayer $GeS$ shows the strongest anisotropy while monolayer $SnS$ and $SnSe$ shows an almost isotropy in phonon transport. The origin of the diverse anisotropy is fully studied and the underlying mechanism is discussed in detail. With limited size, the $\kappa$ could be effectively lowered, and the anisotropy could be effectively modulated by nanostructuring, which would extend the applications in nanoscale thermoelectrics and thermal management. Our study offers fundamental understanding of the anisotropic phonon transport properties of 2D materials, and would be of significance for further study, modulation and aplications in emerging technologies.Comment: 14 pages, 8 figures, 2 table

Application of nursing core competency standard education in the training of nursing undergraduates

AbstractPurposeTo evaluate the effectiveness of nursing core competency standard education in undergraduate nursing training.MethodsForty-two nursing undergraduates from the class of 2007 were recruited as the control group receiving conventional teaching methods, while 31 students from the class of 2008 were recruited as the experimental group receiving nursing core competency standard education. Teaching outcomes were evaluated using comprehensive theoretical knowledge examination and objective structured clinical examination.ResultsThe performance in the health information collection, physical assessment, scenario simulation and communication in the experimental group were significantly higher than those of the control group (p < 0.05).ConclusionsNursing core competency standard education is helpful for the training of nursing students' core competencies

Hemostatic, anti-inflammatory and antibacterial effects of Sanqixiantao dressing in vivo and in vitro

Purpose: To study the hemostatic, anti-inflammatory and antibacterial effects of Sanqixiantao dressing.Methods: Sanqixiantao dressing was prepared by mixting with sanqixiiantao extract (8 %) with membrane-forming matrix (5:4:9:2 volume ratio of polyvinyl alcohol: Na CMC: gelatin: glycerol). Rats with local surface wounds were used to evaluate the effects of Sanqixiantao dressing on hemostatic time, wound healing time and infection rate. Serum levels of tumor necrosis factor (TNF)-α and interleukin (IL) 6 were determined. The anti-inflammatory and analgesic effects of Sanqixiantao extracts were assessed by dimethylbenzene-induced ear edema and acetic acid-induced abdominal writhing tests. In in vitro studies, the effect of the extract on blood clotting time, and its antibacterial activities against six pathogenic bacteria (Escherichia coli, Staphylococous aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis, Clostridium perfringens and Clostridium tetani) were evaluated.Results: Sanqixiantao dressing significantly decreased hemostatic time (p &lt; 0.01), wound healing time (p &lt; 0.01) and infection rate (10 vs 100 %), when compared to control rats. Sanqixiantao extract significantly shortened blood clotting time in vitro (p &lt; 0.01), and showed antibacterial activities against E. coli (minimum inhibitory concentration, MIC: 0.4 mg/mL, MBC: 1.6 mg/mL), S. aureus (MIC: 0.8 mg/mL, minimum bacterial concentration, MBC: 3.2 mg/mL), P. aeruginosa (MIC: 0.8 mg/mL, MBC: 3.2 mg/mL), S. epidermidis (MIC: 1.6 mg/mL, MBC: 3.2 mg/mL). Besides, Sanqixiantao extracts (100, 200, 400 and 600 mg/kg) dose-dependently decreased dimethyl-benzene-induced ear edema and acetic acid-induced abdominal writhes in mice (p &lt; 0.05, p &lt; 0.01, p &lt; 0.01, p &lt; 0.01).Conclusion: The results demonstrate that Sanqixiantao dressing has significant hemostatic, antiinflammatory and antibacterial effects in vivo and in vitro, and thus provide some support for the therapeutic application of Sanqixiantao dressing for treating skin wounds.Keywords: Sanqixiantao dressing, Acute skin wound, Hemostatic, Anti-inflammatory activity, Antibacterial effect, Herbal medicin

catena-Poly[[[diiodidomercury(II)]-μ-N,N′-di-3-pyridylpyridine-2,6-dicarboxamide] dimethyl­formamide solvate]

In the title complex, {[HgI2(C17H13N5O2)]·C3H7NO}n, the Hg atom is coordinated by two I atoms and two N atoms from two different ligands in a distorted tetra­hedral environment. Hg atoms are bridged by N,N′-di-3-pyridylpyridine-2,6-dicarboxamide ligands, forming a helical chain running along the a axis

Adiabatic sound velocity and compressibility of a trapped d-dimensional ideal anyon gas

The adiabatic sound velocity and compressibility for harmonically trapped ideal anyons in arbitrary dimensions are calculated within Haldane fractional exclusion statistics. The corresponding low-temperature and high-temperature behaviors are studied in detail. To compare with the experimental result of unitary fermions, the sound velocity for anyons in the cigar-shaped trap is derived. The sound velocity for anyons in the disk-shaped trap is also calculated. With the parameter g=0.287, the sound velocity of unitary fermions in the cigar-shaped trap modeled by anyons is in good agreement with the experimental result, while that of unitary fermions in the disk-shaped trap is v_{0}/v_{F}=0.406 with Fermi velocity v_{F}.Comment: 16 pages, 6 figure, elsarticle.cls, minor changes with typos correcte

On the measurement of the Hubble constant in a local low-density universe

Astrophysical observations indicate that the ``Local Universe" has a relatively lower matter density ($\Omega_0$) than the predictions of the standard inflation cosmology and the large-scale motions of galaxies which provide a mean mass density to be very close to unity. In such a local underdense region the Hubble expansion may not be representative of the global behaviour. Utilizing an underdense sphere embedded in a flat universe as the model of our ``Local Universe", we show that the local Hubble constant would be 1.2 -- 1.4 times larger than the global value on scale of $\sim80$ Mpc, depending on the variation of $\Omega_0$. This may account for the recent measurements of the unpleasantly large Hubble constant of $\sim$80 km/s/Mpc using the Cepheid variables in the Virgo cluster and the relative distance between Virgo and Coma cluster and removes the resulted apparent paradox of the age of our universe.Comment: 9 pages, Latex file, 3 figures available by reques