Spatiotemporal distribution, light absorption characteristics, and source apportionments of black and brown carbon in China.

Black carbon (BC) and brown carbon (BrC) are aerosols that absorb light and thereby contribute to climate change. In this study, the light absorption properties and spatiotemporal distributions of equivalent BC (eBC) and BrC aerosols were determined based on continuous measurements of aerosol light absorption from January to August 2017, using a seven-channel aethalometer at 49 sampling sites in China. The source apportionments of BC and BrC were identified using the BC/PM2.5, absorption Ångström exponent, the concentration-weighted trajectory method, and the random forest model. Based on the results, BC was the dominant light absorber, whereas BrC was responsible for a higher proportion of the light absorption in northern compared to southern China. The light absorption of BrC was highest in winter (34.3 Mm-1), followed by spring (19.0 Mm-1) and summer (3.6 Mm-1). The combustion of liquid fuels accounted for over 50 % of the light absorption coefficient of BC in most cities and the importance of carbon monoxide (CO) and nitrogen dioxide (NO2) was over 10 % for BC emitted by liquid fuel combustion, based on the random forest model. The contribution of solid fuel combustion to BC in the north was larger than that in the southern regions as coal combustion and crop residue burning are important emission sources of BC in most northern cities. The contribution of primary BrC to light absorption was high in some northern cities, whereas that of secondary BrC was prevalent in some southern cities. The diurnal variations in secondary BrC were affected by changes in odd oxygen and relative humidity, which promoted the photobleaching of the chromophores and aqueous-phase reactions of secondary BrC.

Effects of Nongxiangxing baijiu (Chinese liquor) on mild alcoholic liver injury revealed by non-target metabolomics using ultra-performance liquid chromatography quadrupole-time-of-flight mass spectrometry.

Nongxiangxing baijiu (Chinese liquor) is one of the most widely consumed beverages in China. This liquor has been shown to contain large quantities of various bioactive ingredients that are beneficial to health. The goals of the present study were to examine the effects of moderate dose Nongxiangxing baijiu on alcoholic liver injury in rats, and to explore the mechanism of action of Nongxiangxing baijiu on alcoholic liver injury. To accomplish these goals, we developed a metabolomic analysis method based on ultra-performance liquid chromatography quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF/MS) analysis and multivariate statistical analysis. Our serum lipid and hepatic histopathology results demonstrate that ethanol administration induced mild alcoholic liver injury in rats. However, these ethanol-induced changes were significantly alleviated in the Nongxiangxing baijiu group. These results suggest that moderate dose Nongxiangxing baijiu might have a preventive effect on mild alcoholic liver injury. Using our metabolomics method, we were able to identify 45 differential metabolites in serum and urine which could be used to characterize mild alcoholic liver injury in rats. Of these, 15 differential metabolites, including four Lysophosphatidylethanolamines, two phosphatidylcholines, four long-chain fatty acids, one porphyrin, two esters, one ceramide, and one triol, were regulated by Nongxiangxing baijiu. KEGG metabolic pathway analysis revealed that the main metabolic pathway regulated by Nongxiangxing baijiu was the glycerolipid pathway. Together, these findings provide evidence that moderate dose Nongxiangxing baijiu can reduce mild alcoholic liver injury (including metabolic disorders). Our study also provides preliminary data on the mechanism of action of Nongxiangxing baijiu in liver injury.

Flexible SnTe/carbon nanofiber membrane as a free-standing anode for high-performance lithium-ion and sodium-ion batteries.

Flexible electrode plays a key role in flexible energy storage devices. The SnTe/C nanofibers membrane (SnTe/CNFM) with excellent mechanical flexibility has been successfully synthesized for the first time through electrospinning, and it demonstrates outstanding electrochemical performance as free-standing anode for lithium/sodium-ion batteries. The SnTe/CNFM electrode delivers a discharge capacity of 526.7 mAh g-1 at 1000 mA g-1 after 1000 cycles in lithium-ion half-cells and a discharge capacity of 236.5 mAh g-1 at 500 mA g-1 after 80 cycles in lithium-ion full-cells with a LiFePO4 cathode. Not only that, it shows a discharge capacity of 182.7 mAh g-1 at 200 mA g-1 after 200 cycles in sodium-ion half-cells and a high discharge capacity of 207.0 mAh g-1 at 500 mA g-1 after 50 cycles in sodium-ion full-cells with a Na0.44MnO2 cathode. Moreover, the prepared SnTe/CNFM exhibits good mechanical flexibility. The SnTe/CNFM can still return to its original state without any breakage after bending, curling, folding and kneading. These results indicate that SnTe/CNFM is expected to become one of the promising free-standing anodes for lithium/sodium-ion batteries.

A flexible Mn0.5Ti2(PO4)3/C nanofiber film with superior cycling stability for potassium-ion batteries.

First-principles calculations indicate that Mn0.5Ti2(PO4)3 is more suited to potassium-ion storage because of its lower energy gap than that of KTi2(PO4)3. A flexible Mn0.5Ti2(PO4)3/C nanofiber film (F-MTP/C NFF) has been first synthesized via electrospinning and applied to potassium-ion batteries as a self-standing anode. An integral carbon conductive network, unique one-dimensional nanostructure, and exceptional mechanical flexibility give F-MTP/C NFF outstanding potassium-ion storage performance. Impressively, the self-standing F-MTP/C NFF electrode delivers a high specific capacity of 218 mA h g-1 at 0.02 A g-1 and shows ultra-long cycling stability of 2000 cycles at 1 A g-1. This work may give a new insight into developing NASICON-type Ti-based materials as flexible electrodes for potassium-ion batteries.

Wire-in-Wire TiO2/C Nanofibers Free-Standing Anodes for Li-Ion and K-Ion Batteries with Long Cycling Stability and High Capacity.

Wearable and portable mobile phones play a critical role in the market, and one of the key technologies is the flexible electrode with high specific capacity and excellent mechanical flexibility. Herein, a wire-in-wire TiO2/C nanofibers (TiO2 ww/CN) film is synthesized via electrospinning with selenium as a structural inducer. The interconnected carbon network and unique wire-in-wire nanostructure cannot only improve electronic conductivity and induce effective charge transports, but also bring a superior mechanic flexibility. Ultimately, TiO2 ww/CN film shows outstanding electrochemical performance as free-standing electrodes in Li/K ion batteries. It shows a discharge capacity as high as 303 mAh g-1 at 5 A g-1 after 6000 cycles in Li half-cells, and the unique structure is well-reserved after long-term cycling. Moreover, even TiO2 has a large diffusion barrier of K+, TiO2 ww/CN film demonstrates excellent performance (259 mAh g-1 at 0.05 A g-1 after 1000 cycles) in K half-cells owing to extraordinary pseudocapacitive contribution. The Li/K full cells consisted of TiO2 ww/CN film anode and LiFePO4/Perylene-3,4,9,10-tetracarboxylic dianhydride cathode possess outstanding cycling stability and demonstrate practical application from lighting at least 19 LEDs. It is, therefore, expected that this material will find broad applications in portable and wearable Li/K-ion batteries.

Red phosphorus embedded in TiO2/C nanofibers to enhance the potassium-ion storage performance.

TiO2-red phosphorus/C nanofibers (TiO2-RP/CN) have been synthesized via electrospinning and then annealed with red phosphorus sublimation. Benefiting from the high electronic/ionic conductivity and robust stability of the unique structure, the TiO2-RP/CN show high reversible capacities, as well as an outstanding cycling ability. In K half cells, the capacity decay of the TiO2-RP/CN electrode mainly occurs in the first few cycles, and at 0.05 A g-1 it delivers a high specific capacity of 257.8 mA h g-1 after 500 cycles. K full cells were fabricated; these are well-matched with PTCDA (perylene-3,4,9,10-tetracarboxylic dianhydride) and also exhibited a good electrochemical performance (62 mA h g-1 after 100 cycles). Therefore, the TiO2-RP/CN are potential anode materials for use in K-ion batteries.

Boosting the charge transfer of Li2TiSiO5 using nitrogen-doped carbon nanofibers: towards high-rate, long-life lithium-ion batteries.

Li2TiSiO5 (LTSO) has a theoretical specific capacity of up to 315 mA h g-1 with a suitable working potential (0.28 V vs. Li/Li+). However, the electronic structure of Li2TiSiO5 is firstly investigated by theoretical calculation based on the first-principles approach, and the results demonstrate that Li2TiSiO5 acts as the insulator for transferring electrons. Therefore, the framework with better conductivity is very essential for Li2TiSiO5 to enhance the charge transfer kinetics. Nitrogen-doped carbon encapsulated Li2TiSiO5 nanofibers (LTSO/NDC nanofibers) are obtained by using carbamide as a nitrogen source through an electrospinning technique. The nitrogen-doped carbon matrix with high electronic conductivity improves the electrochemical properties of LTSO significantly. The diffusion coefficient of lithium ions (DLi+) is greatly improved by manual calculation. The LTSO/NDC nanofiber electrode can deliver 371.7 mA h g-1 at 0.1 A g-1 and 361.1 mA h g-1 at 0.2 A g-1, and also shows a comparable cycle performance which could endure a long cycle over 800 cycles at 0.5 A g-1 almost without capacity decay. Hence, the LTSO/NDC nanofiber anode with a high rate and a long life provides a new direction for the realization of LTSO-based compounds in lithium ion batteries.