26 research outputs found
Non-monotonic dynamic correlations beneath the surface of glass-forming liquids
Collective motion over increasing length scales is a signature of the
vitrification process of liquids. We demonstrate the emergence of distinct
static and dynamic length scales probed near the free surface in fully
equilibrated glass-forming liquid films, and their connection to the bulk
properties of the system. In contrast to a monotonically growing static
correlation length, the dynamic correlation length that measures the extent of
surface-dynamics acceleration into the bulk, displays a striking non-monotonic
temperature evolution that is robust also against changes in detailed
interatomic interaction. The maximum of dynamic correlations defines a
cross-over temperature that we show to agree with a morphological change
of cooperative rearrangement regions (CRR) of fast particles in the bulk
liquids. The cross-over occurs at a temperature larger than the critical
temperature Tc of mode-coupling theory (MCT). We link it to the point where
fast-particle motion decouples from structural relaxation that can be defined
rigorously within a recent extension of MCT, the stochastic -relaxation
theory (SBR)
Nonmonotonic Dynamical Correlations beneath the Surface of Glass-Forming Liquids
Collective motion over increasing length scales is a signature of the vitrification process of liquids. We demonstrate how distinct static and dynamic length scales govern the dynamics of vitrifying films. In contrast to a monotonically growing static correlation length, the dynamical correlation length that measures the extent of surface-dynamics acceleration into the bulk displays a striking nonmonotonic temperature evolution that is robust also against changes in detailed interatomic interaction. This nonmonotonic change defines a crossover temperature T* that is distinct from the critical temperature Tc of mode-coupling theory. We connect this nonmonotonic change to a morphological change of cooperative rearrangement regions of fast particles, and to the point where the decoupling of fast-particle motion from the bulk relaxation is most sensitive to fluctuations. We propose a rigorous definition of this new crossover temperature T* within a recent extension of mode-coupling theory, the stochastic beta-relaxation theory
Hormonal regulation of ovarian bursa fluid in mice and involvement of aquaporins.
In rodent species, the ovary and the end of oviduct are encapsulated by a thin membrane called ovarian bursa. The biological functions of ovarian bursa remain unexplored despite its structural arrangement in facilitating oocytes transport into oviduct. In the present study, we observed a rapid fluid accumulation and reabsorption within the ovarian bursa after ovarian stimulation (PMSG-primed hCG injection), suggesting that the ovarian bursa might play an active role in regulating local fluid homeostasis around the timing of ovulation. We hypothesized that the aquaporin proteins, which are specialized channels for water transport, might be involved in this process. By screening the expression of aquaporin family members (Aqp1-9) in the ovarian tissue and isolated ovarian bursa (0, 1, 2 and 5 h after hCG injection), we found that AQP2 and AQP5 mRNA showed dynamic changes after hCG treatment, showing upregulation at 1-2 h followed by gradually decrease at 5 h, which is closely related with the intra-bursa fluid dynamics. Further immunofluorescence examinations of AQP2 and AQP5 in the ovarian bursa revealed that AQP2 is specifically localized in the outer layer (peritoneal side) while AQP5 localized in the inner layer (ovarian side) of the bursa, such cell type specific and spatial-temporal expressions of AQP2 and 5 support our hypothesis that they might be involved in efficient water transport through ovarian bursa under ovulation related hormonal regulation. The physiological significance of aquaporin-mediated water transport in the context of ovarian bursa still awaits further clarification
Drosophila homologs of mammalian TNF/TNFR-related molecules regulate segregation of Miranda/Prospero in neuroblasts
Mutations in ACTL6B Cause Neurodevelopmental Deficits and Epilepsy and Lead to Loss of Dendrites in Human Neurons
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203584.pdf (publisher's version ) (Open Access
Ultralow Phase Noise Optoelectronic Oscillator and Its Application to a Frequency Synthesizer
We propose a novel injection-locked OptoElectronic Oscillator (OEO) with ultralow phase noise based on two cascaded phase modulators, which is further applied to construct a frequency synthesizer. Thanks to the phase modulation, the output optical spectrum expands and the optical power keeps constant while passing through the optical fiber, which dramatically reduces the intensity noise induced by the nonlinear effects of the optical fiber. A dual-output MZI together with a balanced optical detector realizes the phase modulation to intensity modulation conversion and improves the signal to noise ratio of the OEO. The output frequency of the proposed OEO is 9.9999914 GHz with its sidemode suppression ratio larger than 85 dB, and the phase noise reaches –153.1 dBc/Hz at 10 kHz frequency offset which is 38.7 dB lower than that of Keysight E8257D. Moreover, a broadband, high performance frequency synthesizer is established based on the proposed OEO. Combining the DDS and PLL technologies, the proposed frequency synthesizer can cover 5.9~12.9 GHz range. The phase noise is around –130 dBc/Hz@10 kHz, the spur suppression ratio is better than 65 dB, and the frequency hopping time is less than 1.48 μs
Local structures and undercooling ability of Zr-Ti melts
We developed an accurate model of Zr-Ti melts for classical molecular-dynamics simulations via regauging the existing embedded-atom method (EAM) potential, using particularly the diffusion coefficient data obtained from quasielastic neutron scattering. This EAM potential well reproduces the properties of the melts observed in experiments, including mass density, transport coefficients, melting temperatures, and static structure factors. The latter are also obtained from ab initio simulations. Using the developed EAM potentials, we analyzed the short-range order of the liquids and found a chemically preferred formation of Zr-Zr and Zr-Ti nearest neighbor pairs. When decreasing the temperature the number of icosahedral-like aggregates increases on the expense of more crystal-like structures. This is most pronounced at intermediate alloy compositions. At intermediate compositions also the lowest thermodynamic driving force for crystallization is found, resulting in the largest undercooling ability of the alloys