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Abstract Space debris laser ranging with a 4.2 W double-pulse 532 nm picosecond laser at a pulse repetition frequency of 1 kHz was achieved at the Shanghai satellite laser ranging (SLR) station, which receiving telescope was 60 cm. Space debris' radar cross sections were from 2 m2 to 12 m2, and ranging precision was up to centimeters. A compound regenerative amplifier was used to realize double pulses output with pulse space of 4.1 ns. Double pulses would have the same detection ability as the equal energy single pulse. A 500 μm diameter avalanche photo-diode detector with less than 10 kHz dark noise and a quantum efficiency of 40% at 532 nm was developed to improve the measurement capability. And also a spectral filter with high efficiency and narrow bandwidth were applied. Basing on the Shanghai SLR system, the laser ranging to space debris with picosecond laser at 1 kHz was successfully implemented for the first time among the global SLR stations. The results showed that the ranging precision root-mean-square can be achieved about 5 cm. It will be very useful to monitor and study the space debris. [ABSTRACT FROM AUTHOR]

An average power of 3 W green picosecond laser at a pulse repetition frequency of 1 kHz was reported. At the Shanghai satellite laser ranging (SLR) station, many satellites were measured with this laser and a narrow spectrum filter in the daytime. Satellites of the Beidou satellite navigation system for the Chinese, Global navigation satellite system for the Russian and Galileo satellite navigation system for the Europe were measured respectively. Especially ranging precision root mean square was up to 19.4 mm for the satellite of compassi5 about 37,000 km far from the earth. A Nd:YVO 4 mode-locked laser with an etalon, a dual-length of Nd:YAG regenerative amplification cavity, single-pass two Nd:YAG modules amplifier and nonlinear optical materials LiB 3 O 5 frequency doubling were designed. An average power of 3 W in 532 nm was obtained with pulse width of 30 ps, and angle of divergence was 0.8 mrad. Using the dual-length of regenerative cavity would greatly decrease the laser's volume and improve stability of picosecond laser. A narrow spectrum filter can reduce a lot of optics noise from the sun, and so all the satellites were almost be measured with this laser in the daytime at the Shanghai SLR station. [ABSTRACT FROM AUTHOR]

To obtain size distribution of nanoparticles, scanning electron microscope (SEM) and transmission electron microscopy (TEM) have been widely adopted, but manual measurement of statistical size distributions from the SEM or TEM images is time-consuming and labor-intensive. Therefore, automatic detection methods are desirable. This paper proposes an automatic image processing algorithm which is mainly based on local adaptive Canny edge detection and modified circular Hough transform. The proposed algorithm can utilize the local thresholds to detect particles from the images with different degrees of complexity. Compared with the results produced by applying global thresholds, our algorithm performs much better. The robustness and reliability of this method have been verified by comparing its results with manual measurement, and an excellent agreement has been found. The proposed method can accurately recognize the particles with high efficiency. [ABSTRACT FROM AUTHOR]

• Cost-effective monitoring methods is needed to detect CO 2 leakage in carbon sequestration. • Our method does not need time-lapse imaging and directly detects CO 2 leak mass from raw seismic data. • Our leakage detection method are based on densely connected convolutional neural networks. In carbon capture and sequestration (also known as carbon capture and storage, or CCS), developing effective monitoring methods is needed to detect and respond to CO 2 leakage. CO 2 leakage detection methods rely on geophysical observations and monitoring sensor network. However, traditional methods usually require the development of site-specific physical models and expert interpretation, and the effectiveness of these methods can be limited to different application locations, operational scenarios, and conditions. In this paper, we developed a novel data-driven leakage detection method based on densely connected convolutional neural networks. Our method is an end-to-end detection approach, that differs from conventional leakage monitoring methods by directly learning a mapping relationship between seismic data and the CO 2 leakage mass. To account for the spatial and temporal characteristics of seismic data, our novel networks architecture combines 1D and 2D convolutional neural networks. To overcome the computational expense of solving optimization problems, we apply a densely-connecting strategy in our network architecture that reduces the number of network parameters. Based on the features generated by our convolutional neural networks, we further incorporate a long short-term memory network to utilize time-sequential information, which further improves the detection accuracy. Finally, we employ our detection method to synthetic seismic datasets generated based on flow simulations of a hypothetical CO 2 storage scenario with injection into a partially compartmentalized sandstone storage reservoir. To evaluate method performance, we conducted multiple experiments including a random leakage test, a sequential test, and a robustness test. Numerical results show that our CO 2 leakage detection method successfully detects the leakage and accurately predicts the leakage mass, suggesting that it has the potential for application in monitoring of real CO 2 storage sites. [ABSTRACT FROM AUTHOR]

The losses of Superconducting Magnetic Energy Storage (SMES) magnet are not neglectable during the power exchange process with the grid. In order to prevent the thermal runaway of a SMES magnet, quantitative analysis of its thermal status is inevitable. In this paper, the loss characteristics of a self-developed 150 kJ SMES magnet are analyzed by means of experiments and simulations, including the loss of the joint resistance, the eddy current loss of the metal cooling structures and the AC loss of the superconducting magnet. A thermal model of the magnet was built to theoretically analyze the relationship between the current and magnet temperature variation. Three kinds of power compensation experiments were carried out to study the thermal characteristics of the SMES magnet. The temperature variation of the magnet under these three operating conditions was simulated. The simulation results and experimental results are compared and analyzed. [ABSTRACT FROM AUTHOR]

This study sought to monitor the dynamic process of lymph node (LN) metastasis with intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI), and to investigate the impact of disease course on the detection of metastatic LNs by IVIM-DWI. Twenty female New Zealand rabbits with 2.5–3.0 kg body weight were studied. VX2 cells and egg yolk emulsion were randomly inoculated into one thigh to induce metastatic and inflammatory popliteal LNs, respectively. Eight rabbits underwent IVIM-DWI (14 b values, 0–2000 s/mm2) 2 h prior to, and 14, 21, and 28 days after inoculation (D0, D14, D21, D28). The apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) were measured and compared between the metastatic and the inflammatory groups at each time point. Three rabbits randomly chosen from the remaining twelve rabbits were sacrificed at each time point to perform hematoxylin and eosin staining and histologic evaluation. The patterns of dynamic change of D*, ADC, and D were different between the metastatic and the inflammatory LNs. The metastatic group had a lower D* value at D14 (p =.003), and greater ADC and D values at both D21 (p =.001, p =.001) and D28 (p =.021, p =.001), compared to the inflammatory group. The f value of the metastatic group was greater than that of the inflammatory only at D28 (p =.001). IVIM-DWI can reflect the dynamic process of LN metastasis, and disease course has a significant influence on the ability of IVIM-DWI to detect metastatic nodes. [ABSTRACT FROM AUTHOR]

BeiDou navigation satellite System (BDS), was the dedicated Chinese Global Navigation Satellite Systems (GNSS). The satellites in the BDS constellation can be tracked by many Satellite Laser Range (SLR) stations, making use of the onboard Laser Retro-reflector Array (LRA). Additionally, some of BDS satellites were also equipped with Laser Time Transfer (LTT) payloads. The measuring data from these instruments provided highly accurate estimations of satellites orbit, and time comparison between satellites and ground clocks.The performance of the BDS LRA and LTT payloads designed by Shanghai Astronomical Observatory (SHAO) were presented, as well as the SLR systems with a one meter-aperture telescope, which provided the ranging precision of centimeter levels for daylight ranging to BDS satellites at the synchronous orbit. For the first time, high precise LTT measurements at the synchronous orbit satellites were performed by the SHAO. The LTT data processing and analysis were presented with the time stability of 20ps at 500s, and a relative frequency stability of 10E-14.The further developments and improvements of Chinese LTT technology were also discussed. Global SLR tracking of BDS satellites were performed by the International Laser Ranging Service, providing accurate range data with global coverage. By using laser data, the accuracy of BDS satellite orbit and broadcast ephemeris were evaluated and the orbit error of BDS satellites was achieved at the meter level. [ABSTRACT FROM AUTHOR]

Most of efforts have been made to prepare high performance surface-enhanced Raman scattering (SERS) substrate for amplifying Raman signals. It still remains a grand challenging task in building a simple, conventional and low-cost SERS substrate with highly dense hotspots for improved sensitivity of the target analytes. Here, we report a very dexterous strategy to fabricate a distinctive SERS substrate with high density hotspots, using common adsorbent activated carbon (AC) as template to assemble silver nanoparticles (Ag NPs). It can be estimated that the enhancement effect of Ag NPs/AC composite is about 6.5-fold that of bare Ag NPs. Different from the resonant dyes, however, formaldehyde (FA) is a Raman-inactive molecule even though enhanced. Considering that, a novel method for quantitative analysis of FA using the Ag NPs/AC composite as SERS sensor has been developed, based on the catalytic effect of trace FA on the oxidation of malachite green (MG) through bromate under acidic condition. The change of MG from reduced form into oxidized leucomalachite green (LMG) results in the quench of Raman signals of MG, responding to 0.07 ppb FA that is about 2 orders of magnitude lower than the limit defined by the Nash's method as a standard procedure recommended in Europe, Japan and China. Moreover, SERS examinations of endogenous FA in human urine signify that the proposed method has high selectivity, reliability and accuracy. Thus, as-fabricated Ag NPs/AC composite is adequate as inexpensive and versatile SERS sensor utilized in the quantification of trace targets in various complicated matrices. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the value of intravoxel incoherent motion (IVIM) histogram analysis based on whole tumor volume in predicting microvascular invasion (MVI) of single hepatocellular carcinoma (HCC).Materials and Methods: The study enrolled 41 patients with pathologically proven HCCs who underwent IVIM diffusion-weighted imaging with nine b values and contrast-enhanced magnetic resonance imaging (MRI). Histogram parameters including mean; skewness; kurtosis; and percentiles (5th, 10th, 25th, 50th, 75th, 90th, 95th) were derived from apparent diffusion coefficient (ADC), perfusion fraction (f), true diffusion coefficient (D), and pseudo diffusion coefficient (D*). Quantitative histogram parameters and clinical data were compared between HCCs with and without MVI. For significant parameters, receiver operating characteristic (ROC) curves were further plotted to compare the diagnosis performance for identifying MVI.Results: The mean, 5th, 10th, 25th, 50th, and 75th percentiles of D, and the 5th, 10th, and 25th percentiles of ADC between HCCs with and without MVI were statistically significant (all P＜0.05). The histogram parameters of D* and f showed no statistically significant differences between HCCs with and without MVI (all P＞0.05). The areas under the ROC curves (AUCs) were 0.707-0.874 for D and 0.668-0.720 for ADC. The largest AUC of D (5th percentile) showed significantly higher accuracy than that of ADC or tumor size (P = 0.009-0.046). With a cut-off of 0.403 × 10-3 mm²/s, the 5th percentile of D value provided a sensitivity of 81% and a specificity of 85% in the prediction of MVI.Conclusions: Histogram analysis of IVIM based on whole tumor volume can be useful for predicting MVI. The 5th percentile of D was most useful value to predict MVI of HCC. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) regulating the release of free zinc ions (Zn 2+ ) in cellular lysosome is closely related to various pathways of cellular signal transduction, such as inflammation and oxidative stress. Directly visualizing Zn 2+ release in lysosome is essential for in-depth understanding these physiological processes, and is still an atelic challenge. In this work, we successfully fabricate a lysosome-specific Zn 2+ fluorescent probe and achieve the visualization of ROS-induced Zn 2+ release in lysosome of inflammatory cells. The as-prepared probe combines a green fluorophore, an ionophore with five-dentate sites, and a morpholine as the lysosome-specific localization moiety. The fluorescence of the fluorophore in the free probe is suppressed by a photoinduced electron transfer (PET) process from nitrogen atoms in the ionophore. Upon the addition of Zn 2+ , the fluorescence can be promoted immediately, achieving the real-time detection. Meanwhile, the probe is sensitive and selective to Zn 2+ , which provides the capability to detect low-concentration of free Zn 2+ in lysosomes. Accordingly, the Zn 2+ release was clearly observed in lysosome with the increase of ROS levels when the inflammation occurred in living cells. [ABSTRACT FROM AUTHOR]

Objective The objective was to investigate the capabilities of diffusional kurtosis imaging (DKI) in detection of age-related white matter (WM) changes in elderly patients with leukoaraiosis. Material and methods Fractional anisotropy (FA), kurtosis, and diffusion parameters in the frontal lobe and parietal lobe were compared between 14 patients at Fazekas scale 0 and 1, and 15 patients at Fazekas scale 2 and 3. Results FA and DKI parameters were significantly altered in the ischemic lesions vs normal regions of WM in the severe patients. Conclusion DKI can provide sensitive imaging biomarkers for assessing the severity of leukoaraiosis in reference to Fazekas score. [ABSTRACT FROM AUTHOR]

The intracellular pH value controls many aspects of cell metabolism and is considered as an integral part of many metabolic reactions by maintaining the structure and function of nearly all proteins. Detection of pH fluctuation covering the whole intracellular pH window including both neutral and acidic is essential but challenging and still needs more sensitive pH probes. We have synthesized a new near-infrared fluorescent and colorimetric probe based on cyanine dye, which can be used for monitoring the pH fluctuation. The probe has a good water solubility, excellent photostability, reversibility, low cytotoxicity and exhibits a good performance to detect pH fluctuation in both solution and live cells. Upon incubation with live cells, it responds sensitively to low pH value in cell medium by exhibiting bright red fluorescence. On the contrary, the fluorescence intensity of probe seems to be very weak in neutral cellular environment. The satisfactory results show that the probe was a highly sensitive pH probe in living cells and further demonstrate its promising biological applications. [ABSTRACT FROM AUTHOR]

The real applications of Na 3 V 2 (PO 4 ) 3 cathode material for sodium batteries have been hindered by low-cost and facile synthesis method. Herein, we report a facile self-combustion method to synthesize Na 3 V 2 (PO 4 ) 3 nanoparticles coated with carbon shell (NVP/C). Using as the cathode, the NVP/C is capable of delivering the initial discharge and charge capacities of 100.72 and 111.3 mAh g −1 at the current of 0.1 C in a voltage of 2.5–3.8 V, and the capacity retention of the sample is approximately 95% of its initial specific capacity after 50th cycles. The first-principles simulation results show that the Na ions migration route prefers between two adjacent tetrahedral sites with the vacancy-hopping mechanism in a curved way, with the lowest activation energy of 0.292 eV. The diffusion coefficients D Na + at room temperature was also calculated as higher as 2.38 × 10 −9 cm 2 s −1 . The results suggest great potential of self-combustion synthesized NVP/C as cathode materials for Na-ion batteries. [ABSTRACT FROM AUTHOR]

Investigating the interactions between lipid droplets (LDs) and other organelles are greatly significant to the in-depth understand the physiology and pathology of LDs. Despite of commercial LDs probes available, the ER and other membrane structures are also stained due to their amphiphilicity, which limits their further applications. To address this issue, we herein report a highly hydrophobic fluorescent probe to specifically label intracellular LDs with high signal/noise ratio, avoiding undesirable staining of ER and thus achieving to real-time monitor the interactions between LDs and other organelles. The probe showed strong emission in lipid environments but no fluorescence in water and liposomes, enabling the probe with high signal/noise ratio. Using this probe, it was found that the contacts of LDs with ER and mitochondria clearly increased under the condition of starvation. • A highly hydrophobic fluorescent molecule was successfully synthesized, which can specifically target lipid droplets. • The signal-to-noise ratio of the synthesized fluorescent probe is much higher than that of commercial dyes. • The interactions of lipid droplets with mitochondria and endoplasmic reticulum were studied. [ABSTRACT FROM AUTHOR]

Recent advancements in super-resolution nanoscopy allowed the study of mitochondrial biology at nanoscale and boosted the understanding its correlated cellular processes those were previously poorly understood. Nevertheless, studying mitochondrial ultrastructure remains a challenge due to the lack of probes that could target specific mitochondrial substances (e.g. cristae or mtDNA) and survive under harsh super-resolution optical conditions. Herein, in this work, we have rationally constructed a pyridine-BODIPY (Py-BODIPY) derivative that could target mitochondrial membrane in living cells without interfering its physiological microenvironments. Furthermore, we found Py-BODIPY is a membrane potential independent probe, hence it is not limit to live-cell staining but also showed a strong internalization into pre-fixed and stimulus disrupted sample. Importantly, its cristae specificity and superb photostability allow the observation of mitochondrial dynamic nano-structures with an unprecedented resolution, allow demonstrating how mitochondrial 3D ultrastructure evolved under oxidative phosphorylation condition. • Py-BODIPY is a ΔΨm independent mitochondrial probe. • Py-BODIPY showed superb photostability and increased cristae resolution. • Py-BODIPY revealed mitochondrial 3D dynamics at nanoscale. [ABSTRACT FROM AUTHOR]

Lipid droplets (LDs) ultrastructure progression under proteohormone stimulation provide valuable clues for understanding conditions associated with obesity and diabetes. Current available LDs probes either alter intra-LDs environments or lack photo-resistance; thus, this research domain is poorly understood. In this work, a N–B–O type BODIPY- hexylcarbazole derivative named BoCz-Lip was rationally designed while achieving specific LDs live-cell targeting. BoCz-Lip showed minimal impact on cell viability as well as internal LDs' protein, triglyceride and cholesterol level. Along with its good photostability, it can be used to monitor LDs evolution under super-resolution nanoscopy. More importantly, we concluded how proteohormone could influence LDs ultrastructure, offering a better understanding for correlating diseases at the nanoscale. • BoCz-Lip has specific fluorescent response against LDs' phospholipids. • BoCz-Lip to uncover LDs morphology under STED nanoscopy. • BoCz-Lip showed minimal impact on cell viability as well as internal LDs' protein, triglyceride and cholesterol level. [ABSTRACT FROM AUTHOR]

Investigating lipid droplets (LDs) behaviours is essential to deeply understand the physiology of LDs, such as their growths, movements, fusion/division, and autophagy. Among these behaviours, the growth of LDs is one of the most difficult to track due to the very subtle morphology evolution in a short time window. The major obstacle is that conventional LDs-specific dyes with low photostability cannot indicate the LDs' size change. To address this issue, we synthesize a hydrophobic and photostable fluorescent dye (TPA-AD) and load it into the neutral lipid micelles (as artificial adiposomes). The highly hydrophobic TPA-AD enables the specific accumulation into intracellular LDs and the ready loading artificial adiposomes. When the intracellular LDs take TPA-AD-labeled adiposomes, by fusion, the sizes of LDs gradually grow, and LDs are simultaneously lighted up by the fluorescence of TPA-AD. Importantly, the high photostability of TPA-AD ensures the enhanced fluorescence signals. The finding here will further strengthen the understanding of LDs dynamics and fat metabolism. Image 1 • A hydrophobic fluorescent compound was synthesized and employed to label lipid droplets and artificial adiposomes. • The as-synthesized fluorescent compound had much better photostability than commercial dyes. • A new strategy that dye-loaded into artificial adiposomes can track the intracellular lipid droplets growth. • The growth of lipid droplets with the subtle morphology changes in short time was successfully visualized. [ABSTRACT FROM AUTHOR]