Anisotropic intrinsic lattice thermal conductivity of phosphorene from first principles

Phosphorene, the single layer counterpart of black phosphorus, is a novel two-dimensional semiconductor with high carrier mobility and a large fundamental direct band gap, which has attracted tremendous interest recently. Its potential applications in nano-electronics and thermoelectrics call for a fundamental study of the phonon transport. Here, we calculate the intrinsic lattice thermal conductivity of phosphorene by solving the phonon Boltzmann transport equation (BTE) based on first-principles calculations. The thermal conductivity of phosphorene at $300\,\mathrm{K}$ is $30.15\,\mathrm{Wm^{-1}K^{-1}}$ (zigzag) and $13.65\,\mathrm{Wm^{-1}K^{-1}}$ (armchair), showing an obvious anisotropy along different directions. The calculated thermal conductivity fits perfectly to the inverse relation with temperature when the temperature is higher than Debye temperature ($\Theta_D = 278.66\,\mathrm{K}$). In comparison to graphene, the minor contribution around $5\%$ of the ZA mode is responsible for the low thermal conductivity of phosphorene. In addition, the representative mean free path (MFP), a critical size for phonon transport, is also obtained.Comment: 5 pages and 6 figures, Supplemental Material available as http://www.rsc.org/suppdata/cp/c4/c4cp04858j/c4cp04858j1.pd

The Yeast GSK-3 Homologue Mck1 Is a Key Controller of Quiescence Entry and Chronological Lifespan.

Upon starvation for glucose or any other core nutrient, yeast cells exit from the mitotic cell cycle and acquire a set of G0-specific characteristics to ensure long-term survival. It is not well understood whether or how cell cycle progression is coordinated with the acquisition of different G0-related features during the transition to stationary phase (SP). Here, we identify the yeast GSK-3 homologue Mck1 as a key regulator of G0 entry and reveal that Mck1 acts in parallel to Rim15 to activate starvation-induced gene expression, the acquisition of stress resistance, the accumulation of storage carbohydrates, the ability of early SP cells to exit from quiescence, and their chronological lifespan. FACS and microscopy imaging analyses indicate that Mck1 promotes mother-daughter cell separation and together with Rim15, modulates cell size. This indicates that the two kinases coordinate the transition-phase cell cycle, cell size and the acquisition of different G0-specific features. Epistasis experiments place MCK1, like RIM15, downstream of RAS2 in antagonising cell growth and activating stress resistance and glycogen accumulation. Remarkably, in the ras2∆ cells, deletion of MCK1 and RIM15 together, compared to removal of either of them alone, compromises respiratory growth and enhances heat tolerance and glycogen accumulation. Our data indicate that the nutrient sensor Ras2 may prevent the acquisition of G0-specific features via at least two pathways. One involves the negative regulation of the effectors of G0 entry such as Mck1 and Rim15, while the other likely to involve its functions in promoting respiratory growth, a phenotype also contributed by Mck1 and Rim15.This work was funded by a scholarship from Lucy Cavendish College (ZQ) and a scholarship awarded by National University of Defense Technology of China (LC). This work was also supported by the UNICELLSYS Collaborative Project (No. 201142) of the European Commission awarded to SGO.This is the published version. It first appeared at http://dx.doi.org/10.1371/journal.pgen.100528

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

An Approach to Identifying the Biomechanical Differences Between Intercostal Cartilage in Subjects with Pectus Excavatum and Normals \u3ci\u3ein Vivo\u3c/i\u3e: Reconstruction and CT Registration

Pectus excavatum (PE) is a congenital chest wall deformity affecting the ribs and sternum and exhibiting a concave appearance in the anterior chest wall. In this thesis, we describe a study to investigate in vivo differences in the pectus excavatum rib cage and outline steps using normals and pectus patients data in developing models and methods to be used in carrying out the study. We propose methods to develop reconstructed models in order to enable proper registration between data collection points (DCPs) on the 3D CT rib cage model and CT skin surface model and registration between CT surrogate models and 3D laser surface scan model with actual DCPs. A Polhemus Fastscan 3D laser scanner is used to produce a non-invasive way of quantifying the surface of the subject\u27s chest, which can then be compared with the 3D reconstructed CT model to estimate the errors with these procedures. The results show that the minimum average error of the simulated DCPs after translation for the pectus patients (\u3c2 \u3emm) is much less than that of the Visible Human male and \u3e60% actual DCPs are distributed on the intercostal cartilages

Pharmacokinetics/pharmacodynamics of marbofloxacin in a Pasteurella multocida serious murine lung infection model

The ARRIVE Guidelines Checklist. Animal Research: Reporting In Vivo Experiments. (PDF 391 kb

Sample-Based Online Generalized Assignment Problem with Unknown Poisson Arrivals

We study an edge-weighted online stochastic \emph{Generalized Assignment Problem} with \emph{unknown} Poisson arrivals. In this model, we consider a bipartite graph that contains offline bins and online items, where each offline bin is associated with a $D$-dimensional capacity vector and each online item is with a $D$-dimensional demand vector. Online arrivals are sampled from a set of online item types which follow independent but not necessarily identical Poisson processes. The arrival rate for each Poisson process is unknown. Each online item will either be packed into an offline bin which will deduct the allocated bin's capacity vector and generate a reward, or be rejected. The decision should be made immediately and irrevocably upon its arrival. Our goal is to maximize the total reward of the allocation without violating the capacity constraints. We provide a sample-based multi-phase algorithm by utilizing both pre-existing offline data (named historical data) and sequentially revealed online data. We establish its performance guarantee measured by a competitive ratio. In a simplified setting where $D=1$ and all capacities and demands are equal to $1$, we prove that the ratio depends on the number of historical data size and the minimum number of arrivals for each online item type during the planning horizon, from which we analyze the effect of the historical data size and the Poisson arrival model on the algorithm's performance. We further generalize the algorithm to the general multidimensional and multi-demand setting, and present its parametric performance guarantee. The effect of the capacity's (demand's) dimension on the algorithm's performance is further analyzed based on the established parametric form. Finally, we demonstrate the effectiveness of our algorithms numerically

Impaired tumor angiogenesis and VEGF-induced pathway in endothelial CD146 knockout mice

This research aims to develop mathematical teaching materials based on sharia economy for madrasah tsanawiyah students with good quality. The method used in the study is the development model adapted from Borg & Gall is the preliminary stage, development, and validation. The preliminary stage includes literature studies, analysis of the needs and characteristics of students, and to plan and choose the design of teaching materials. The development phase includes determining the competence standard, basic competence, indicators, and the subject matter, compiling teaching materials math, and prepare research instruments. The validation phase includes validation expert and revisions. Results of the study are social arithmetic teaching materials based on sharia economy. Each material begins with the problem of economic comparison of Islamic and conventional. The feasibility of the value of teaching materials is Very Good for aspects of the look and Very Good for the material aspects. With these criteria very well, teaching materials are feasible for use in the learning of mathematics in the social arithmetic material