Stimulated Raman Scattering Microscopy Reveals Bioaccumulation of Small Microplastics in Protozoa from Natural Waters.

Microplastics (MPs) are pollutants of global concern, and bioaccumulation determines their biological effects. Although microorganisms form a large fraction of our ecosystem's biomass and are important in biogeochemical cycling, their accumulation of MPs has never been confirmed in natural waters because current tools for field biological samples can detect only MPs > 10 µm. Here, we show that stimulated Raman scattering microscopy (SRS) can image and quantify the bioaccumulation of small MPs (<10 µm) in protozoa. Our label-free method, which differentiates MPs by their SRS spectra, detects individual and mixtures of different MPs (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polystyrene, and poly(methyl methacrylate)) in protozoa. The ability of SRS to quantify cellular MP accumulation is similar to that of flow cytometry, a fluorescence-based method commonly used to determine cellular MP accumulation. Moreover, we discovered that protozoa in water samples from Yangtze River, Xianlin Wastewater Treatment Plant, Lake Taihu and the Pearl River Estuary accumulated MPs < 10 µm, but the proportion of MP-containing cells was low (∼2-5%). Our findings suggest that small MPs could potentially enter the food chain and transfer to organisms at higher trophic levels, posing environmental and health risks that deserve closer scrutiny.

Controlled Synthesis of Single-Crystalline Ni-Rich Cathodes for High-Performance Lithium-Ion Batteries.

Single-crystalline LiNi0.8Co0.1Mn0.1O2 (NCM811) has been considered as one of the most promising cathode materials. It addresses the pulverization issue present in its polycrystalline counterpart by eliminating intergranular cracks. However, synthesis of high-performance single-crystalline NCM is still a challenge owing to the lower structure stability of NCM811 at high calcination temperatures (≥900 °C), which is often required to grow single crystals. Herein, we report a synthesis process for microsized single-crystalline NCM811 particles with exposed (010) facets on their lateral sides [named as SC-NCM(010)], which includes the preparation of a well-dispersed microblock-like Ni0.8Co0.1Mn0.1(OH)2 precursor through coprecipitation assisted with addition of PVP and Na2SiO3 and subsequent lithiation of the precursor at 800 °C. The SC-NCM(010) cathode exhibits an excellent capacity retention rate (91.6% after 200 cycles at 1 C, 4.3 V) and a high rate capability (152.2 mAh/g at 20 C, 4.4 V), much superior to those of polycrystalline NCM811 cathodes. However, despite the removal of interparticle boundaries, when cycled between 2.8 and 4.5 V, the SC-NCM(010) cathode still suffers from structural changes including lattice gliding and intragranular cracking. These structural changes are correlated with the interior structural inhomogeneity, which is evidenced by the coexistence of H2 and H3 phases in the fully deintercalated state.

Improved Zero-Charge Storage Performance of LiCoO2/Mesocarbon Microbead Lithium-Ion Batteries by Li5FeO4 Cathode Additive.

Discharging lithium-ion batteries to zero-charge state is one of the most reliable ways to avoid the thermal runaway during their transportation and storage. However, the zero-charge state causes the degradation or even complete failure of lithium-ion batteries. Specialized solutions are required to endow lithium-ion batteries with improved zero-charge storage performance, namely, the ability to tolerate zero-charge state for a long time without unacceptable capacity loss. Here, we report that a Li5FeO4 cathode additive can improve the zero-charge storage performance of LiCoO2/mesocarbon microbead (MCMB) batteries. The irreversible charge capacity of the Li5FeO4 additive results in the downregulation of anode and cathode potentials when the battery is at zero-charge state. More importantly, the Li5FeO4 additive offers a small discharge plateau below 2.9 V versus Li/Li+, which can hold the anode potential at zero-charge battery state (APZBS) in a potential range of 2.4∼2.5 V versus Li/Li+ during storage for 10 days. Such a precise control on APZBS not only suppresses the decomposition of the solid electrolyte interface film on the MCMB anode and inhibits the dissolution of the copper current collector occurring at high potentials but also avoids the excessive decrease of the cathode potential at the zero-charge battery state and consequently protects the LiCoO2 cathode from overlithiation occurring at low potentials. As a result, the Li5FeO4 additive with a charge capacity percentage of 23% in the cathode increases the capacity recovery ratio of the LiCoO2/MCMB battery from 37.6 to 95.5% after being stored at the zero-charge state for 10 days.

[Spatial and Temporal Distribution Characteristics and the Retention Effects of Nutrients in Xiangjiaba Reservoir].

After the construction of the Xiangjiaba Dam, the hydrodynamic conditions, nutrient distributions, and transport conditions of the Jinsha River were changed. Here, the nutrient distribution characteristics and retention effects of Xiangjiaba Reservoir were investigated according to the results of water quality monitoring from 2015 to 2016. Spatial and temporal variations in TN, TP, SiO32-Si, and other nutrients, and retention flux and retention rate were analyzed. The results showed that the nutrient mass concentration of TN, TP, and SiO32--Si was 0.905 mg·L-1, 0.034 mg·L-1, and 7.98 mg·L-1, respectively. The distribution of TN was affected by point sources and the concentration of TN was large in urban areas. This distribution of TP was mainly granular and the mass concentrations decreased along the river path. The mass concentration of SiO32--Si did not significantly vary over time and space. Furthermore, Xiangjiaba Reservoir had a persistent effect on nutrient salts; the average annual retention of TN, TP, and SiO32--Si was 2.30×104 t·a-1, 0.146×104 t·a-1, and -2.4×104 t·a-1, respectively. During different seasons, the retention of TN and SiO32--Si varied between positive or negative; however, TP appeared to be consistent. The average monthly retention efficiency of TN, TP, and SiO32--Si was 17.5%, 32.8%, and -2.14%, respectively. Overall, retention efficiencies were higher during the dry season than that wet season, and phosphorus retention was most pronounced. The retention of TN in the reservoir may be related to denitrification and the input of external load; the flux of SiO32--Si was mainly affected by runoff; and the particle morphology of phosphorus, as well as reservoir period, were the main factors affecting TP retention. There were no clear correlations between nutrient retention and the mass concentrations of TN and SiO32--Si, but the nutrient retention effect of Xiangjiaba Reservoir reduced TP concentrations along the river path and increased TP concentration with vertical depth.

Electrophoretically Deposited p-Phenylene Diamine Reduced Graphene Oxide Ultrathin Film on LiNi0.5Mn1.5O4 Cathode to Improve the Cycle Performance.

Spinel LiNi0.5Mn1.5O4 (LNMO) has been considered as one of the most promising candidate cathode materials for power lithium-ion batteries. However, its cycle performance suffers from the increasing impedance of the LNMO-cathode/electrolyte interface (LNMO-CEI) layer caused by parasitic reactions on the electrode surface at high operating potentials. To address the capacity degradation upon cycling, we present a feasible way to realize electrode modification by electrophoretically deposited graphene ultrathin films on the exterior surface of the LNMO cathodes without decreasing the electrode density. A p-phenylene diamine reduced graphene oxide (pPD-rGO) film with an area density of 20 µg/cm2 not only increases the capacity retention rate of the 1000th cycle at 4.2-5.2 V from 71.7 to 81.7% but also boosts the specific capacity from 110.6 to 122.4 mAh/g. X-ray photoelectron spectroscopy (XPS) spectra reveal that the pPD-rGO film with Lewis-base nature increases the content of LiF and reduces the number of RCFx groups in the cycled electrode, indicating the consumption of high-potential-generated F radicals by the pPD-rGO film. Such consumption favors the formation of a robust interphase between the pPD-rGO film and the electrolyte, which could hinder the sustained production of F radicals, consequently stabilize the LNMO-CEI layer, and improve the cycle performance. An electrophoretically deposited Lewis-acid GO film of 20 µg/cm2 reduces the specific capacity and fails to work as the pPD-rGO film. The chemical process for the formation of interphase on the GO film is similar to that on the bare LNMO electrode.

Molecular-Scale Structure of Electrode-Electrolyte Interfaces: The Case of Platinum in Aqueous Sulfuric Acid.

Knowledge of the molecular composition and electronic structure of electrified solid-liquid interfaces is key to understanding elemental processes in heterogeneous reactions. Using X-ray absorption spectroscopy in the interface-sensitive electron yield mode (EY-XAS), first-principles electronic structure calculations, and multiscale simulations, we determined the chemical composition of the interfacial region of a polycrystalline platinum electrode in contact with aqueous sulfuric acid solution at potentials between the hydrogen and oxygen evolution reactions. We found that between 0.7 and 1.3 V vs Ag/AgCl the electrical double layer (EDL) region comprises adsorbed sulfate ions with hydrated hydronium ions in the next layer. No evidence was found for bisulfate or Pt-O/Pt-OH species, which have very distinctive spectral signatures. In addition to resolving the long-standing issue of the EDL structure, our work establishes interface- and element-sensitive EY-XAS as a powerful spectroscopic tool for studying condensed phase, buried solid-liquid interfaces relevant to various electrochemical processes and devices.

X-ray-Induced Fragmentation of Imidazolium-Based Ionic Liquids Studied by Soft X-ray Absorption Spectroscopy.

We investigated the X-ray absorption spectroscopy (XAS) fingerprint of EMImTFSI ionic liquid (IL) and its fragmentation products created by X-ray irradiation. To accomplish this, we used an open geometry where an IL droplet is directly exposed in the vacuum chamber and an enclosed geometry where the IL is confined in a cell covered by an X-ray transparent membrane. In the open geometry, the XAS signature was stable and consistent with experimental and theoretical spectra reported in the literature. In contrast, when the IL is enclosed, its XAS evolves continuously under X-ray illumination due to the accumulation of volatile fragmentation products inside the closed cell, while they evaporate in the open geometry. The changes in the XAS from the core levels of relevant elements (C, N, S, F) together with density functional theory calculations allowed us to identify the chemical nature of the fragment products and the chemical bonds most vulnerable to rupture under soft X-ray irradiation.

Dopamine-Induced Formation of Ultrasmall Few-Layer MoS2 Homogeneously Embedded in N-Doped Carbon Framework for Enhanced Lithium-Ion Storage.

Molybdenum disulfide with a layered structure and high theoretical capacity is attracting extensive attention for high-performance lithium-ion batteries. In this study, a simple and scalable method by freeze-drying of (NH4)2MoS4 and dopamine mixed solutions along with subsequent calcination is developed to realize the self-assembly of hierarchical MoS2/carbon composite nanosheets via the effect of dopamine-induced morphology transformation, in which ultrasmall few-layer MoS2 nanosheets were homogeneously embedded into a N-doped carbon framework (denoted as MoS2@N-CF). The embedded ultrasmall MoS2 nanosheets (∼5 nm in length) in the composites consist of less than five layers with an expanded interlayer spacing of the (002) plane. When tested as anode materials for rechargeable Li-ion batteries, the obtained MoS2@N-CF nanosheets exhibit outstanding electrochemical performance in terms of high specific capacity (839.2 mAh g-1 at 1 A g-1), high initial Coulombic efficiency (85.2%), and superior rate performance (702.1 mAh g-1 at 4 A g-1). Such intriguing electrochemical performance was attributed to the synergistic effect of uniform dispersion of few-layer MoS2 into the carbon framework, expanded interlayer spacing, and enhanced electronic conductivity in the unique hierarchical architecture. This work provides a simple and effective strategy for the uniform integration of MoS2 with carbonaceous materials to significantly boost their electrochemical performance.

Fabrication of mesoporous metal oxide coated-nanocarbon hybrid materials via a polyol-mediated self-assembly process.

After clarifying the formation mechanism of a typical metal glycolate precipitate, Ti glycolate, in a polyol-mediated synthesis using acetone as a precipitation medium, we describe a simple template-free approach based on an ethylene glycol-mediated synthesis to fabricate mesoporous metal oxide coated-nanocarbon hybrid materials including TiO2 coated-carbon nanotube (CNT), SnO2 coated-CNT, Cu2O/CuO coated-CNT and TiO2 coated-graphene sheet (GS). In the approach, metal oxide precursors, metal glycolates, were first deposited on CNTs or GSs, and subsequently transformed to the metal oxide coatings by pyrolysis or hydrolysis. By a comparison between the characterization of two TiO2-CNT hybrid materials using carboxylated CNTs and pristine CNTs without carboxyl groups, the driving force for initiating the deposition of metal glycolates on the carboxylated CNTs is confirmed to be the hydrogen bonding between the carboxyl groups and the polymer chains in metal glycolate sols. The electrochemical performances of the mesoporous TiO2 coated-carboxylated CNTs and TiO2-pristine CNT hybrid materials were investigated. The results show that the mesoporous TiO2 coated-carboxylated CNT with a uniform core-shell nanostructure exhibits substantial improvement in the rate performance in comparison with its counterpart from 0.5 C to 100 C because of its higher electronic conductivity and shorter diffusion path for the lithium ion. At the extremely high rate of 100 C, the specific capacity of TiO2 of the former reaches 85 mA h g(-1), twice as high as that of the latter.

Comparison of the rate capability of nanostructured amorphous and anatase TiO2 for lithium insertion using anodic TiO2 nanotube arrays.

Nanostructured amorphous and anatase TiO2 are both considered as high rate Li-insertion/extraction electrode materials. To clarify which phase is more desirable for lithium ion batteries with both high power and high density, we compare the electrochemical properties of anatase and amorphous TiO2 by using anodic TiO2 nanotube arrays (ATNTAs) as electrodes. With the same morphological features, the rate capacity of nanostructured amorphous TiO2 is higher than that of nanostructured anatase TiO2 due to the higher Li-diffusion coefficient of amorphous TiO2 as proved by the electrochemical impedance spectra of an amorphous and an anatase ATNTA electrode. The electrochemical impedance spectra also prove that the electronic conductivity of amorphous TiO2 is lower than that of anatase TiO2. These results are helpful in the structural and componential design of all TiO2 mesoporous structures as anode material in lithium ion batteries. Moreover, all the advantages of the amorphous ATNTA electrode including high rate capacity, desirable cycling performance and the simplicity of its fabrication process indicate that amorphous ATNTA is potentially useful as the anode for lithium ion batteries with both high power and high energy density.

[Inversion results of the atmospheric environment detecting airborne lidar in Qingdao, Bohai and Yellow Sea area].

Without the hypothesis of atmospheric parameters and auxiliary equipment, it is proven the slope method is capable of deriving extinction coefficients profiles and atmosphere optical depth through the analysis of the atmospheric environment detecting airborne lidar (AEDAL) data collected during November 7 to 11, 2005. The spatial and temporal variations of the planet boundary layer (PBL), aerosol optical depth (AOD) of the PBL and aerosol distribution along flight lines are exhibited from the AEDAL inversion results. Firstly, the sinking of aerosol was found in Yellow Sea area, moreover, the PBL altitude also dropped while the multi-layer aerosol presented after a cold front passage; secondly, the AOD of the PBL is the highest over Qingdao city, the lowest over foothill area and in between them over sea area, Meanwhile, it is relatively stable over sea area but slightly increases nearby upslope. The AOD values of the PBL were determined to be 0.15-0.35 in clear day and 0.3-0.45 in foggy day over the area from Qingdao to Bohai, but they are higher and reach around 0.55 in Yellow Sea area. It is evidenced that the aerosol in the PBL mainly comes from city and also is contributed by salt sea over Qingdao area, and ridge and surface wind play an important role in the aerosol transport while the monsoon affects the aerosol distribution.

Amorphous TiO(2) nanotube arrays for low-temperature oxygen sensors.

Titania nanotube arrays (TNTA) were synthesized on a titanium substrate using anodic oxidation in an electrolyte containing ammonium fluoride and evaluated for low-temperature oxygen sensing. Their sensing properties were tested at different temperatures (50, 100, 150, 200, 250 and 300 °C) when exposed to various oxygen concentrations. The as-prepared TNTA are amorphous and exhibit much higher carrier concentration than that of annealed TNTA. Such amorphous TNTA show much higher sensitivity than that of annealed TNTA, SrTiO(3) and Ga(2)O(3) sensors. This sample demonstrates the lowest detectable oxygen concentration of 200 ppm, excellent recovery and good linear correlation at 100 °C. These results indicate that TNTA are indeed very attractive oxygen-sensing materials.

[Determination of eleutheroside B in antifatigue fraction of Acanthopanax senticosus by HPLC].

OBJECTIVE: To develop an HPLC method for the determination of eleutheroside B in As1 (the extract fraction from Acanthopanax senticosus, which has a good effect of antifatigue). METHOD: The antifatigue effect of Asl was evaluated by mice burden swimming testing. One compound was isolated by silica gel, Sephadex LH-20 column chromatography and preparative high performance liquid chromatography. The structure was identified by physicochemical properties and spectral evidences. Eleutheroside B in Asl was determined by HPLC. Chromatographic conditions included Diamonsil C18 column (4.6 mm x 250 mm, 5 microm) and the mobile phase consisting of a mixture of acetonitrile-water-ethanoic acid (10: 90: 0.01). The UV detection wavelength was set at 344 nm. RESULT: As1 showed an excellent antifatigue activity; One compound was isolated from As1 and its structure was identified as Eleutheroside B; The calibration cure was linear in the range of 0.104-20.8 microg (r = 0.9999), the average recovery was 97.68%, RSD 1.4% (n=6). CONCLUSION: This HPLC method is simple,accurate and reliable.

Effect of pore packing defects in 2-d ordered mesoporous carbons on ionic transport.

Ordered mesoporous materials show great importance in energy, environmental, and chemical engineering. The diffusion of guest species in mesoporous networks plays an important role in these applications, especially for energy storage, such as supercapacitors based on ordered mesoporous carbons (OMCs). The ion diffusion behavior in two different 2-D hexagonal OMCs was investigated by using cyclic voltametry and electrochemical impedance spectroscopy. In addition, transmission electron microscopy, small-angle X-ray diffraction, and nitrogen cryosorption methods were used to study the pore structure variations of these two OMCs. It was found that, for the OMC with defective pore channels (termed as pore packing defects), the gravimetric capacitance was greatly decayed when the voltage scan rate was increased. The experimental results suggest that, for the ion diffusion in 2-D hexagonal OMCs with similar mesopore size distribution, the pore packing defect is a dominant dynamic factor.

Extracting mode components in laser intensity distribution by independent component analysis.

With increasingly sophisticated laser applications in industry and science, a reliable method to characterize the intensity distribution of the laser beam has become a more and more important task. However, traditional optic and electronic methods can offer only a laser beam intensity profile but, cannot separate the main mode components in the laser beam intensity distribution. Recently, independent component analysis has been a surging and developing method in which the goal is to find a linear representation of a non-Gaussian data set. Such a linear representation seems to be able to capture the essential structure of a laser beam profile. After assembling image data of a laser spot, we propose a new analytical approach to extract laser beam mode components based on the independent component analysis technique. For noise reduction and laser spot area location, wavelet thresholding, Canny edge detection, and the Hough transform are also used in this method before extracting mode components. Finally, the experimental results show that our approach can separate the principal mode components in a real laser beam efficiently.

Antinoise approximation of the lidar signal with wavelet neural networks.

We propose a new, to our knowledge, denoising method for lidar signals based on a regression model and a wavelet neural network (WNN) that permits the regression model not only to have a good wavelet approximation property but also to make a neural network that has a self-learning and adaptive capability for increasing the quality of lidar signals. Specifically, we investigate the performance of the WNN for antinoise approximation of lidar signals by simultaneously addressing simulated and real lidar signals. To clarify the antinoise approximation capability of the WNN for lidar signals, we calculate the atmosphere temperature profile with the real signal processed by the WNN. To show the contrast, we also demonstrate the results of the Monte Carlo moving average method and the finite impulse response filter. Finally, the experimental results show that our proposed approach is significantly superior to the traditional methods.