City size based scaling of the urban internal nodes layout

The size of a city is not only essential for depicting the scale of the urban system, but also crucial to support the prosperity, order, and high-speed developments. However, its relation to the underlying urban structure has not been empirically investigated in detail. To examine the impact of city size on the city structure and quantify structural features, in this study, a statistical analysis was performed based on network science and an interdisciplinary theoretical system. To obtain the statistical law of internal node layout, the urban system was regarded as a complete graph weighted by the Euclidean distance. The relationship between the urban internal nodes layout (points of interest data, Weibo check-in data, and central point of road intersection data) and the city size was established. The results confirmed the existence of statistical laws in the layout of urban spatial elements, and explored the relationship between the changes in urban node network structure and inequality. This study provided a new perspective of urban structure to understand the complexity of the city, and suggested an approach to adjust this structure to narrow down the gap between the urban and rural areas

Quantitative fluorimetric analysis of plant nicotinamide

Fluorimetry was used to measure the amount of nicotinamide in plant samples. The nicotinamide was extracted and purified from plant tissues with ethyl acetate; converted to the fluorescent derivative, N1-methylnicotinamide, by reacting with methyl iodide; and quantified according to its fluorescent strength. The nicotinamide in the leaf tissue of ten kinds of plants was measured, and the results showed that the nicotinamide content for different plants varied from 0.1 to 3.0 mg/g of fresh leaf weight. In addition, the crossing value of the fluorescent strength and the nicotinamide amount demonstrated that the linear correlation coefficient generally reached 0.997, with a detectable limit of 0.02 mg/L and the relative standard deviation of less than 9%. The results suggested that this method of quantifying nicotinamide in plants is useful and beneficial for functional research

The warming Tibetan Plateau improves winter air quality in the Sichuan Basin, China

Impacts of global climate change on the occurrence and development of air pollution have attracted more attention. This study investigates impacts of the warming Tibetan Plateau on air quality in the Sichuan Basin. Meteorological observations and ERA-Interim reanalysis data reveal that the plateau has been rapidly warming during the last 40 years (1979-2017), particularly in winter when the warming rate is approximately twice as much as the annual warming rate. Since 2013, the winter temperature over the plateau has even risen by 2 degrees C. Here we use the WRF-Chem model to lay emphasis on the impact of the 2 degrees C warming on air quality in the basin. The model results show that the 2 degrees C warming causes an enhanced easterly wind, an increase in the planetary boundary layer height (PBLH) and a decrease in the relative humidity (RH) in the basin. Enhanced easterly wind increases PM2.5 transport from the basin to the plateau. The elevated PBLH strengthens vertical diffusion of PM2.5, while the decreased RH significantly reduces secondary aerosol formation. Overall, PM2.5 concentration is reduced by 17.5 % (similar to 25.1 mu g m(-3)), of which the reduction in primary and secondary aerosols is 5.4 and 19.7 mu g m(-3) respectively. These results reveal that the recent warming plateau has improved air quality in the basin, to a certain extent mitigating the air pollution therein. Nevertheless, the climate system is particularly complicated, and more studies are needed to demonstrate the impact of climate change on air quality in the downstream regions as the plateau is likely to continue warming

Multifaceted Roles of Retromer in EGFR Trafficking and Signaling Activation

Mammalian retromer complex contributes to multiple early endosome-associated trafficking pathways whose origins are dependent on which sorting nexin (SNX) they are complexed with. In an attempt to dissect out the contribution of individual retromer–SNX complexes, we examined the trafficking of EGFR in detail within a series of KO cell line models. We demonstrated that the depletion of retromer subunit Vps35 leads to decreased EGFR protein levels in resting cells with enhanced association of EGFR with lysosomal compartments. Compared to control cells, the addition of EGF to Vps35 KO cells resulted in a reduced rate of EGFR degradation; AKT activation and cell prolferation rates were elevated, while ERK activation remained relatively unchanged. These observations are consistent with a prolonged temporal association of EGFR within early endosomes due to the inefficiency of early endosome-associated protein trafficking pathways or organelle maturation due to retromer absence. We did not fully delineate the discrete contributions from retromer-associated SNXs to the phenotypes observed from retromer Vps35 depletion. While each of the knock-outs of SNX1/2, SNX3, or SNX27 promotes the enhanced association of EGFR with early endosomal compartments, only the decreased EGF-mediated EGFR degradation was observed in SNX1/2 dKO cells, while the enhanced AKT activation was only increased in SNX3 KO or SNX27 KO cells. Despite this, each of the knock-outs showed increased EGF-stimulated cell proliferation rates

Exploration of the Fluorescent Properties and the Modulated Activities against Sirtuin Fluorogenic Assays of Chromenone-Derived Natural Products

Chromenone-derived natural products include chromones (flavone, isoflavone) and coumarins. Chromenone compounds not only exhibit impressive biological activities, but also are an important resource of experimentally used fluorophores, such as, 7-amino-4-methylcoumarin (AMC). Various chromenone compounds have reported to have weak fluorescence, and this has the potential to interfere with the measurements during AMC fluorogenic assays and result in non-robust assay readouts. Several flavones and isoflavones were found as SIRT1 activators, while fluorogenic sirtuin assays utilized AMC labelled peptides as the substrates. In this study we investigated whether the fluorescent properties of chromenone-derived natural products interrupt the measurement of SIRT1/2 modulated activities. We found that the reported SIRT1 activators: flavones were detected with the SIRT1 activation activity, but isoflavones were not detected with SIRT1 activation activity, and instead that they were found to be fluorogenic compounds. Another chromenone compound, osthole, exhibited a moderate SIRT2 inhibitory activity with an IC50 of 10 μM. In conclusion, the fluorescent properties of these chromenone compounds do affect the measurement of the sirtuin activities of both inhibitors and activators. However, if the possible fluorescence properties are mitigated in the assay readout, these fluorogenic assays enable the screening of activity modulators

Electrical characteristics of monofilaments in dielectric barrier discharge plasma jets at atmospheric pressure

Electrical characteristics of monofilaments in dielectric barrier discharge plasma jets were investigated at atmospheric pressure. It is found that the shapes of monofilaments, the discharge current, the number of discharges, the breakdown voltage and the input power are dependent not only on the Ar flow rate but also on the applied voltage and exhibit complicated behaviors. Especially, the discharge current is irregular and has the oscillating pulses with positive and negative polarities. The influence of wall charges on the above parameters was discussed

TEM Investigation of Asymmetric Deposition-Driven Crystalline-to-Amorphous Transition in Silicon Nanowires

Controlling the shape and internal strain of nanowires (NWs) is critical for their safe and reliable use and for the exploration of novel functionalities of nanodevices. In this work, transmission electron microscopy was employed to examine bent Si NWs prepared by asymmetric electron-beam evaporation. The asymmetric deposition of Cr caused the formation of nanosized amorphous-Si domains; the non-crystallinity of the Si NWs was controlled by the bending radius. No other intermediate crystalline phase was present during the crystalline-to-amorphous transition, indicating a direct phase transition from the original crystalline phase to the amorphous phase. Moreover, amorphous microstructures caused by compressive stress, such as amorphous Cr domains and boxes, were also observed in the asymmetric Cr layer used to induce bending, and the local non-crystallinity of Cr was lower than that of Si under the same bending radius

Design, Preparation, and Characterization of a Novel Red Long-Persistent Perovskite Phosphor: Ca₃Ti₂O₇:Pr³⁺

Currently, the development of efficient red-emitting persistent phosphor is still an ongoing challenge. Herein, a novel red-emitting LPL phosphor Ca₃Ti₂O₇:Pr³⁺ is successfully prepared by a high-temperature solid-state method. XRD Rietveld refinement analyses demonstrate the high phase purity of the sample which crystallizes in an orthorhombic <i>Ccm</i>2₁ space group with lattice parameters of <i>a</i> = 5.7702(5) Å, <i>b</i> = 19.4829(7) Å, and <i>c</i> = 5.1214(2) Å. Electronic structure of the host matrix is analyzed by the first-principle calculation using CASTEP code. The calculation results show that Ca₃Ti₂O₇ has a direct band gap with CB and VB mainly composed of the Ti-3d and O-2p states, respectively. On the basis of the DR spectrum, the band gap is determined to be 3.6 eV. It is demonstrated that the 612 nm red-emitting persistent luminescence of Ca₃Ti₂O₇:Pr³⁺ can be either activated by Ti⁴⁺–O^2– → Ti³⁺–O^– host absorption and Pr³⁺–O–Ti⁴⁺ → Pr⁴⁺–O–Ti³⁺ IVCT in the UV region, or Pr³⁺:³H₄ → ³P<i>_J</i> transition in the blue region. The red afterglow can last for ∼5 min observed by the naked eyes in the dark after ceasing the irradiation source. On the basis of the TL analyses, the trap is found exponentially distributed in the host with the depth of 0.69–0.92 eV. Finally, a possible LPL mechanism for Ca₃Ti₂O₇:Pr³⁺ is proposed