Material-driven fibronectin assembly for high-efficiency presentation of growth factors

Growth factors (GFs) are powerful signaling molecules with the potential to drive regenerative strategies, including bone repair and vascularization. However, GFs are typically delivered in soluble format at supraphysiological doses because of rapid clearance and limited therapeutic impact. These high doses have serious side effects and are expensive. Although it is well established that GF interactions with extracellular matrix proteins such as fibronectin control GF presentation and activity, a translation-ready approach to unlocking GF potential has not been realized. We demonstrate a simple, robust, and controlled material-based approach to enhance the activity of GFs during tissue healing. The underlying mechanism is based on spontaneous fibrillar organization of fibronectin driven by adsorption onto the polymer poly(ethyl acrylate). Fibrillar fibronectin on this polymer, but not a globular conformation obtained on control polymers, promotes synergistic presentation of integrin-binding sites and bound bone morphogenetic protein 2 (BMP-2), which enhances mesenchymal stem cell osteogenesis in vitro and drives full regeneration of a nonhealing bone defect in vivo at low GF concentrations. This simple and translatable technology could unlock the full regenerative potential of GF therapies while improving safety and cost-effectiveness

Uplift, Climate and Biotic Changes at the Eocene-Oligocene Transition in Southeast Tibet

The uplift history of southeastern Tibet is crucial to understanding processes driving the tectonic evolution of the Tibetan Plateau and surrounding areas. Underpinning existing palaeoaltimetric studies has been regional mapping based in large part on biostratigraphy that assumes a Neogene modernisation of the highly diverse, but threatened, Asian biota. Here, with new radiometric dating and newly-collected plant fossil archives, we quantify the surface height of part of Tibet’s southeastern margin of Tibet in the latest Eocene (~34 Ma) to be ~3 km and rising, possibly attaining its present elevation (3.9 km) in the early Oligocene. We also find that the Eocene-Oligocene transition in southeastern Tibet witnessed leaf size diminution and a floral composition change from sub-tropical/warm temperate to cool temperate, likely reflective of both uplift and secular climate change, and that by the latest Eocene floral modernization on Tibet had already taken place implying modernization was deeply-rooted in the Paleogene

Surface Fractal Dimension of Single-walled Carbon Nanotubes

Isolated single-walled carbon nanotubes (SWNTs), SWNT bundles, and ropes (or strands) show a structural self-similar characteristic. By calculating the Hausdorff dimension, it was found that their self-similar organization leads to surface fractality and the value of the surface dimension (Ds) depends on self-similar patterns. Experimentally, Ds obtained by nitrogen adsorption measurements at 77.3 K and by the small-angle x-ray scattering technique in our study proved our calculation that the surface dimension of SWNTs is nonintegral,

The Decay Process of an {\alpha}-configuration Sunspot

The decay of sunspot plays a key role in magnetic flux transportation in solar active regions (ARs). To better understand the physical mechanism of the entire decay process of a sunspot, an {\alpha}-configuration sunspot in AR NOAA 12411 was studied. Based on the continuum intensity images and vector magnetic field data with stray light correction from Solar Dynamics Observatory/Helioseismic and Magnetic Imager, the area, vector magnetic field and magnetic flux in the umbra and penumbra are calculated with time, respectively. Our main results are as follows: (1) The decay curves of the sunspot area in its umbra, penumbra, and whole sunspot take the appearance of Gaussian profiles. The area decay rates of the umbra, penumbra and whole sunspot are -1.56 MSH/day, -12.61 MSH/day and -14.04 MSH/day, respectively; (2) With the decay of the sunspot, the total magnetic field strength and the vertical component of the penumbra increase, and the magnetic field of the penumbra becomes more vertical. Meanwhile, the total magnetic field strength and vertical magnetic field strength for the umbra decrease, and the inclination angle changes slightly with an average value of about 20{\deg}; (3) The magnetic flux decay curves of the sunspot in its umbra, penumbra, and whole sunspot exhibit quadratic patterns, their magnetic flux decay rates of the umbra, penumbra and whole sunspot are -9.84 * 10^19 Mx/day, -1.59 * 10^20 Mx/day and -2.60 * 10^20 Mx/day , respectively. The observation suggests that the penumbra may be transformed into the umbra, resulting in the increase of the average vertical magnetic field strength and the reduction of the inclination angle in the penumbra during the decay of the sunspot

Gravitational collapse of a spherical star with heat flow as a possible energy mechanism of gamma-ray bursts

We investigate the gravitational collapse of a spherically symmetric, inhomogeneous star, which is described by a perfect fluid with heat flow and satisfies the equation of state $p=\rho/3$ at its center. In the process of the gravitational collapsing, the energy of the whole star is emitted into space. And the remaining spacetime is a Minkowski one without a remnant at the end of the process. For a star with a solar mass and solar radius, the total energy emitted is at the order of $10^{54}$ {\rm erg}, and the time-scale of the process is about $8s$. These are in the typical values for a gamma-ray burst. Thus, we suggest the gravitational collapse of a spherical star with heat flow as a possible energy mechanism of gamma-ray bursts.Comment: 4 pages, 2 figures, to appear in Commun. Theor. Phy

Tunable Thermal Energy Transport across Diamond Membranes and Diamond-Si Interfaces by Nanoscale Graphoepitaxy

The development of electronic devices, especially those that involve heterogeneous integration of materials, has led to increased challenges in addressing their thermal operational-temperature demands. The heat flow in these systems is significantly influenced or even dominated by thermal boundary resistance at interface between dissimilar materials. However, controlling and tuning heat transport across an interface and in the adjacent materials has so far drawn limited attention. In this work, we grow chemical-vapor-deposited (CVD) diamond on silicon substrates by graphoepitaxy and experimentally demonstrate tunable thermal transport across diamond membranes and diamond-silicon interfaces. We observed the highest diamond-silicon thermal boundary conductance (TBC) measured to date and increased diamond thermal conductivity due to strong grain texturing in the diamond near the interface. Additionally, non-equilibrium molecular-dynamics (NEMD) simulations and a Landauer approach are used to understand the diamond-silicon TBC. These findings pave the way for tuning or increasing thermal conductance in heterogeneously integrated electronics that involve polycrystalline materials and will impact applications including electronics thermal management and diamond growth

Dynamics of multipartite quantum correlations under decoherence

Quantum discord is an optimal resource for the quantification of classical and non-classical correlations as compared to other related measures. Geometric measure of quantum discord is another measure of quantum correlations. Recently, the geometric quantum discord for multipartite states has been introduced by Jianwei Xu [arxiv:quant/ph.1205.0330]. Motivated from the recent study [Ann. Phys. 327 (2012) 851] for the bipartite systems, I have investigated global quantum discord (QD) and geometric quantum discord (GQD) under the influence of external environments for different multipartite states. Werner-GHZ type three-qubit and six-qubit states are considered in inertial and non-inertial settings. The dynamics of QD and GQD is investigated under amplitude damping, phase damping, depolarizing and flipping channels. It is seen that the quantum discord vanishes for p>0.75 in case of three-qubit GHZ states and for p>0.5 for six qubit GHZ states. This implies that multipartite states are more fragile to decoherence for higher values of N. Surprisingly, a rapid sudden death of discord occurs in case of phase flip channel. However, for bit flip channel, no sudden death happens for the six-qubit states. On the other hand, depolarizing channel heavily influences the QD and GQD as compared to the amplitude damping channel. It means that the depolarizing channel has the most destructive influence on the discords for multipartite states. From the perspective of accelerated observers, it is seen that effect of environment on QD and GQD is much stronger than that of the acceleration of non-inertial frames. The degradation of QD and GQD happens due to Unruh effect. Furthermore, QD exhibits more robustness than GQD when the multipartite systems are exposed to environment.Comment: 15 pages, 4 figures, 4 table