Comparing and Merging Observation Data from Ka-Band Cloud Radar, C-Band Frequency-Modulated Continuous Wave Radar and Ceilometer Systems

Field experiment in South China was undertaken to improve understanding of cloud and precipitation properties. Measurements of the vertical structures of non-precipitating and precipitating clouds were obtained using passive and active remote sensing equipment: a Ka-band cloud radar (CR) system, a C-band frequency modulated continuous wave vertical pointing radar (CVPR), a microwave radiometer and a laser ceilometer (CEIL). CR plays a key role in high-level cloud observation, whereas CVPR is important for observing low- and mid-level clouds and heavy precipitation. CEIL helps us diminish the effects of “clear-sky” in the planetary boundary layer. The experiment took place in Longmen, Guangdong Province, China from May to September of 2016. This study focuses on evaluating the ability of the two radars to deliver consistent observation data and develops an algorithm to merge the CR, CVPR and CEIL data. Cloud echo base, thickness, frequency of observed cloud types and reflectivity vertical distributions are analyzed in the radar data. Comparisons between the collocated data sets show that reflectivity biases between the CR three operating modes are less than 2 dB. The averaged difference between CR and CVPR reflectivity can be reduced with attenuation correction to 3.57 dB from the original 4.82 dB. No systemic biases were observed between velocity data collected in the three CR modes and CVPR. The corrected CR reflectivity and velocity data were then merged with the CVPR data and CEIL data to fill in the gaps during the heavy precipitation periods and reduce the effects of Bragg scattering and fog on cloud observations in the boundary layer. Meanwhile, the merging of velocity data with different Nyquist velocities and resolutions diminishes velocity folding to provide fine-grain information about cloud and precipitation dynamics. The three daily periods in which low-level clouds tended to occur were at sunrise, noon and sunset and large differences in the average reflectivity values were observed. Mid- and high-level clouds tended to occur at 1400 and 1800 BT. Few clouds were found between a height of 3 and 5 km

Enhancing Conversion Kinetics through Electron Density Dual‐Regulation of Catalysts and Sulfur toward Room‐/Subzero‐Temperature Na–S Batteries

Abstract Room‐temperature sodium–sulfur (RT Na/S) batteries have received increasing attention for the next generation of large‐scale energy storage, yet they are hindered by the severe dissolution of polysulfides, sluggish redox kinetic, and incomplete conversion of sodium polysulfides (NaPSs). Herein, the study proposes a dual‐modulating strategy of the electronic structure of electrocatalyst and sulfur to accelerate the conversion of NaPSs. The selenium‐modulated ZnS nanocrystals with electron rearrangement in hierarchical structured spherical carbon (Se‐ZnS/HSC) facilitate Na+ transport and catalyze the conversion between short‐chain sulfur and Na2S. And the in situ introduced Se within S can enhance conductivity and form an S─Se bond, suppressing the “polysulfides shuttle”. Accordingly, the S@Se‐ZnS/HSC cathode exhibits a specific capacity of as high as 1302.5 mAh g−1 at 0.1 A g−1 and ultrahigh‐rate capability (676.9 mAh g−1 at 5.0 A g−1). Even at −10 °C, this cathode still delivers a high reversible capacity of 401.2 mAh g−1 at 0.05 A g−1 and 94% of the original capacitance after 50 cycles. This work provides a novel design idea for high‐performance Na/S batteries

Constructing 1D/2D interwoven carbonous matrix to enable high-efficiency sulfur immobilization in Li-S battery

The lithium-sulfur battery is currently considered to be a promising candidate for next-generation energy storage devices. However, its commercial application is severely restricted by rapid capacity decay mainly arising from unavoidable dissolution of intermediate lithium polysulfide of the S-based cathodes. Herein, multifunctional stripped grapheme-carbon nanotubes (SG-CNT) with 1D/2D interwoven and hierarchical pore structure as a promising host to stabilize S was constructed by cheaper raw materials and a facile strategy. Based on comprehensive analysis, the interwoven network and hierarchical pores along with abundant oxidative functional groups in matrix provided large contact area with S, short transport pathway for electrons/Li-ions, sufficient space to accommodate volumetric change, and superior confinement ability for S/polysulfides, thus resulting in effectively stabilizing the S cathode with high S loading and increasing its utilization. Therefore, the S@SG-CNT cathodes exhibited a high reversible capacity of 1227 mAh g-1 at 0.1 A g-1, excellent cyclability with a capacity of 773 mAh g-1 after 500 cycles at 0.2 A g-1, and ultra-long cycling performance with capacity decay less than 0.01% per cycle at 2 A g-1. This facile strategy and unique construction of superior performance cathode provide a new avenue for next commercial application

Enabling a stable room-temperature sodium-sulfur battery cathode by building heterostructures in multichannel carbon fibers

Room-temperature sodium-sulfur (RT Na-S) batteries are widely considered as one of the alternative energy-storage systems with low cost and high energy density. However, the both poor cycle stability and capacity are two critical issues arising from low conversion kinetics and sodium polysulfides (NaPSs) dissolution for sulfur cathodes during the charge/discharge process. Herein, we report a highly stable RT Na-S battery cathode via building heterostructures in multichannel carbon fibers. The TiN-TiO2@MCCFs, fabricated by electrospinning and nitriding techniques, are loaded with the active material S, forming S/TiN-TiO2@MCCFs as the cathode in a RT Na-S battery. At 0.1 A g-1, the cathode produces the capacity of more than 640 mAh g-1 within 100 cycles with a high Coulombic efficiency of nearly 100%. Even at 5 A g-1, the battery still exhibites a capacity of 257.1 mAh g-1 after 1000 cycles. Combining structural and electrochemical analyses with the first-principles calculations reveals that the incorporation of the highly electrocatalytic activity of TiN with the powerful chemisorption of TiO2 well stabilizes S and also alleviates the shuttle effects of polysulfides. This work with simple processes and low cost is expected to promote the further development and application of metal-S batteries.The authors gratefully acknowledge the support of the National Natural Science Foundation of China (51971146 and 51971147). We also acknowledge the support of the Innovation Program of Shanghai Municipal Education Commission (2019-01-07-00-07-E00015), the Shanghai Rising-Star Program (20QA1407100), the General Program of Natural Science Foundation of Shanghai (20ZR1438400), and Shanghai Outstanding Academic Leaders Plan

Lamivudine Concentration in Hair and Prediction of Virologic Failure and Drug Resistance among HIV Patients Receiving Free ART in China

<div><p>Background</p><p>The assessment of adherence to antiretroviral therapy (ART) is important in order to predict treatment outcomes. Lamivudine (3TC) is one of the most widely used NRTIs in China, but its concentrations in hair and association with virologic failure and drug resistance have not been studied.</p><p>Methods</p><p>We conducted a cross-sectional survey to investigate 3TC concentrations in hair as a predictor of virologic failure and drug resistance among HIV patients receiving free ART. We also compared the capacity of hair 3TC concentrations with self-reported adherence in predicting virologic responses. Hair 3TC concentrations were detected through the LC-MS/MS system.</p><p>Results</p><p>In patients without HIV drug resistance (HIVDR), with a threshold hair 3TC concentration of 260 ng/g, the sensitivity and specificity in predicting virologic suppression were 76.9% and 89.9%, respectively. Some factors, including CD4⁺ cell counts, initial treatment regimens with 3TC, and current regimens with second-line drugs, influenced the association between hair 3TC concentrations and virologic suppression. In patients who experienced virologic failure with HIVDR, with a threshold of 180 ng/g, the sensitivity and specificity were 70.0% and 74.4%, respectively. Hair 3TC concentrations had higher sensitivity and specificity in predicting virologic failure and drug resistance than self-reported adherence.</p><p>Conclusions</p><p>The hair 3TC concentration was a stronger indicator than self-reported adherence in predicting virologic failure and drug resistance in HIV patients receiving free ART.</p></div

The box plot of hair 3TC concentration.

<p>The box plot of hair 3TC concentration.</p

Optimizing the threshold of hair 3TC concentration and comparing it with self-reported adherence among HIV patients with viral load≥1000copies/ml and HIVDR (N = 79).

<p>Optimizing the threshold of hair 3TC concentration and comparing it with self-reported adherence among HIV patients with viral load≥1000copies/ml and HIVDR (N = 79).</p

Optimizing the threshold of hair 3TC concentration and comparing it with self-reported adherence among HIV patients without HIVDR (N = 247).

<p>Optimizing the threshold of hair 3TC concentration and comparing it with self-reported adherence among HIV patients without HIVDR (N = 247).</p