2,540 research outputs found

    Biodegradable Polylactic Acid (PLA) Microstructures for Scaffold Applications

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    In this research, we present a simple and cost effective soft lithographic process to fabricate PLA scaffolds for tissue engineering. In which, the negative photoresist JSR THB-120N was spun on a glass subtract followed by conventional UV lithographic processes to fabricate the master to cast the PDMS elastomeric mold. A thin poly(vinyl alcohol) (PVA) layer was used as a mode release such that the PLA scaffold can be easily peeled off. The PLA precursor solution was then cast onto the PDMS mold to form the PLA microstructures. After evaporating the solvent, the PLA microstructures can be easily peeled off from the PDMS mold. Experimental results show that the desired microvessels scaffold can be successfully transferred to the biodegradable polymer PLA.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/EDA-Publishing

    Dynamical Linear Response of TDDFT with LDA+U Functional: strongly hybridized Frenkel excitons in NiO

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    Within the framework of time-dependent density-functional theory (TDDFT), we derive the dynamical linear response of LDA+U functional and benchmark it on NiO, a prototypical Mott insulator. Formulated using real-space Wannier functions, our computationally inexpensive framework gives detailed insights into the formation of tightly bound Frenkel excitons with reasonable accuracy. Specifically, a strong hybridization of multiple excitons is found to significantly modify the exciton properties. Furthermore, our study exposes a significant generic limitation of adiabatic approximation in TDDFT with hybrid functionals and in existing Bethe-Salpeter-equation approaches, advocating the necessity of strongly energy-dependent kernels in future development.Comment: 5 pages, 2 figure

    Charmed Baryon Weak Decays with SU(3) Flavor Symmetry

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    We study the semileptonic and non-leptonic charmed baryon decays with SU(3)SU(3) flavor symmetry, where the charmed baryons can be Bc=(Ξc0,Ξc+,Λc+){\bf B}_{c}=(\Xi_c^0,\Xi_c^+,\Lambda_c^+), Bc=(Σc(++,+,0),Ξc(+,0),Ωc0){\bf B}'_{c}=(\Sigma_c^{(++,+,0)},\Xi_{c}^{\prime(+,0)},\Omega_c^0), Bcc=(Ξcc++,Ξcc+,Ωcc+){\bf B}_{cc}=(\Xi_{cc}^{++},\Xi_{cc}^+,\Omega_{cc}^+), or Bccc=Ωccc++{\bf B}_{ccc}=\Omega^{++}_{ccc}. With Bn(){\bf B}_n^{(\prime)} denoted as the baryon octet (decuplet), we find that the BcBn+ν{\bf B}_{c}\to {\bf B}'_n\ell^+\nu_\ell decays are forbidden, while the Ωc0Ω+ν\Omega_c^0\to \Omega^-\ell^+\nu_\ell, Ωcc+Ωc0+ν\Omega_{cc}^+\to\Omega_c^0\ell^+\nu_\ell, and Ωccc++Ωcc++ν\Omega_{ccc}^{++}\to \Omega_{cc}^+\ell^+\nu_\ell decays are the only existing Cabibbo-allowed modes for BcBn+ν{\bf B}'_{c}\to {\bf B}'_n\ell^+\nu_\ell, BccBc+ν{\bf B}_{cc}\to {\bf B}'_c\ell^+\nu_\ell, and BcccBcc()+ν{\bf B}_{ccc}\to {\bf B}_{cc}^{(\prime)}\ell^+\nu_\ell, respectively. We predict the rarely studied BcBn()M{\bf B}_{c}\to {\bf B}_n^{(\prime)}M decays, such as B(Ξc0Λ0Kˉ0,Ξc+Ξ0π+)=(8.3±0.9,8.0±4.1)×103{\cal B}(\Xi_c^0\to\Lambda^0\bar K^0,\,\Xi_c^+\to\Xi^0\pi^+)=(8.3\pm 0.9,8.0\pm 4.1)\times 10^{-3} and B(Λc+Δ++π,Ξc0ΩK+)=(5.5±1.3,4.8±0.5)×103{\cal B}(\Lambda_c^+\to \Delta^{++}\pi^-,\,\Xi_c^0\to\Omega^- K^+)=(5.5\pm 1.3,4.8\pm 0.5)\times 10^{-3}. For the observation, the doubly and triply charmed baryon decays of Ωcc+Ξc+Kˉ0\Omega_{cc}^{+}\to \Xi_c^+\bar K^0, Ξcc++(Ξc+π+\Xi_{cc}^{++}\to (\Xi_c^+\pi^+, Σc++Kˉ0)\Sigma_c^{++}\bar K^0), and Ωccc++(Ξcc++Kˉ0,Ωcc+π+,Ξc+D+)\Omega_{ccc}^{++}\to (\Xi_{cc}^{++}\bar K^0,\Omega_{cc}^+\pi^+,\Xi_c^+ D^+) are the favored Cabibbo-allowed decays, which are accessible to the BESIII and LHCb experiments.Comment: 29 pages, no figure, a typo in the table correcte

    Compression mechanisms in the anisotropically bonded elements Se and Te

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    [[abstract]]The compression mechanisms of the elements selenium and tellurium (which exhibit highly anisotropic bonding under ambient conditions) are explored. A combination of experiments and ab initio simulation (including generalized gradient corrections) is used to examine the structural and dynamic properties of these elements in detail. The effect of pressure on both these systems is to enhance the weak interchain bonding at the expense of the stronger intrachain covalent interactions. This is manifested by a pronounced mode softening of the intrachain vibrational modes under pressure as found from both Raman spectroscopy and simulation. A corresponding increase of the rigid-chain rotation mode is also revealed by the calculations. We also investigate pressure-induced polymorphism in these materials in order to resolve controversy concerning the high-pressure crystallographic structures.[[notice]]補正完畢[[booktype]]紙本[[countrycodes]]US

    All it takes is empathy:how virtual reality perspective-taking influences intergroup attitudes and stereotypes

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    Research in the past decade has demonstrated the potential of virtual reality perspective-taking (VRPT) to reduce bias against salient outgroups. In the perspective-taking literature, both affective and cognitive mechanisms have been theorized and identified as plausible pathways to prejudice reduction. Few studies have systematically compared affective and cognitive mediators, especially in relation to virtual reality, a medium posited to produce visceral, affective experiences. The present study seeks to extend current research on VRPT’s mechanisms by comparing empathy (affective) and situational attributions (cognitive) as dual mediators influencing intergroup attitudes (affective) and stereotypes (cognitive). In a between-subjects experiment, 84 participants were randomly assigned to embody a VR ingroup or outgroup waiting staff at a local food establishment, interacting with an impolite ingroup customer. Results indicated that participants in the outgroup VRPT condition reported significantly more positive attitudes and stereotypes towards outgroup members than those in the ingroup VRPT condition. For both attitudes and stereotypes, empathy significantly mediated the effect of VRPT, but situational attributions did not. Findings from this research provide support for affect as a key component of virtual experiences and how they shape intergroup perceptions. Implications and directions for further research are discussed
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