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Noble metal-based electrocatalysts present high activities for methanol oxidation reaction (MOR), but are limited by their high cost, low stability and poor resistance to carbon monoxide (CO) poisoning. The development of active and stable non-noble metal electrocatalysts for MOR is desired, but remains a challenge. Herein, we report a simple strategy to make copper nanocrystal/nitrogen-doped carbon (Cu/N-C) monoliths, which can serve as active and robust electrodes for MOR. Copper nanocrystals were electrochemically deposited onto a conductive polyaniline hydrogel and calcined to form Cu/N-C monolith, where the active copper nanocrystals are protected by nitrogen-doped carbon. Owing to their extremely high electrical conductivity (1.25 × 105 S cm−1) and mechanical robustness, these Cu/N-C monoliths can be directly used as electrodes for MOR, without using substrates or additives. The optimal Cu/N-C (FT) @500 monolith shows a high MOR activity of 189 mA cm−2 at 0.6 V vs. SCE in alkaline methanol solution, superior to most of reported Cu-based MOR catalysts. Cu/N-C (FT)@500 also presents a better stability than Pt/C catalyst in the long-term MOR test at high current densities. Upon carbon monoxide (CO) poisoning, Cu/N-C (FT)@500 retains 96% of its MOR activity, far exceeding the performance of Pt/C catalyst (61% retention). Owing to its facile synthesis, outstanding activity, high stability and mechanical robustness, Cu/N-C (FT)@500 monolith is promising as a low-cost, efficient and CO-resistant electrocatalyst for MOR.

Adding redox-active additives into the electrolyte is an effective way to enhance the performance of pseudocapacitive supercapacitors (SCs). However, the applications of these redox-active additives are limited by their high molecular weight and narrow redox potential window. Herein, we report thiourea (TU) as a catalytic redox-active additive to enhance the performance of a supercapacitor based on copper nanocrystal@nitrogen-doped carbon composites (Cu@N-C), whose capacitance was increased 5.9 fold: from 194 mF cm−2 (15.7 mA h g−1, without TU) to 1154 mF cm−2 (93.3 mA h g−1, with TU). The optimized Cu@N-C-600 electrode presents a wide voltage window (1.8 V) and an extremely high capacitance (9571 mF cm−2, 775.4 mA h g−1 at 5 mA cm−2), which is mainly attributed to the pseudocapacitance from the reversible redox reaction of TU and Cu compounds. The porous nitrogen-doped carbon matrix immobilizes and protects the highly active Cu nanocrystals, and also facilitates charge and mass transfer between the electrode and electrolyte. For the symmetrical SC based on Cu@N-C-600, the energy density and power density reach 314 μW h cm−2 and 2798 μW cm−2, respectively, superior to those of most of the inorganic material-based SCs. This work demonstrates that TU is an efficient redox-active additive to improve the performance of pseudocapacitive SCs.

Adipose tissue derived mesenchymal stem cells (ADMSCs) may be an attractive therapeutic source for acute liver injury because of their high accessibility and non-invasiveness. Here, we investigated the therapeutic potentials of porcine ADMSCs for acute liver failure (ALF). The morphology, differentiation potential, expression patterns of cell surface markers and liver-specific genes were compared between the ADMSCs derived from the pigs with or without ALF. For therapeutic studies, the expanded porcine ADMSCs from either ALF pig (ALF-ADMSCs) or healthy control pig (Nor-ADMSCs) of passage 3 were transplanted into CCl(4)-induced ALF mice, and the liver histology and functional tests were performed at days 1, 7, 14, and 21 after cell transplantation. ALF-ADMSCs expressed higher mRNA level of hepatic growth factor (HGF) than the Nor-ADMSCs. Both ALF-ADMSCs and Nor-ADMSCs improved liver histology, functions, and mouse survival rate. Higher level of porcine hepatocyte-specific genes was seen in the livers of ALF-ADMSCs transplanted mice as compared to the Nor-ADMSCs transplanted mice. In particular, ALF-ADMSCs transplanted mice expressed significantly higher level of albumin and cytokeratin 18 in the liver tissues as compared to the Nor-ADMSCs transplanted mice. ALF-ADMSCs might be superior to Nor-ADMSCs in the treatment of ALF as the former possesses stronger hepatic differentiation potential.

Two novel 3D Cd-MOFs, namely {[Cd4(HDDCP)2(4,4′-bibp)2(H2O)2]·2.5(DOA)·1.5(H2O)}n (1) and {[Cd2(HDDCP)(1,4-bib)(H2O)]·H2O}n (2), where H5DDCP = 2,4-di(2′,5′-dicarboxylphenyl)benzoic acid, 4,4′-bibp = 4,4′-bis(imidazolyl)biphenyl and 1,4-bib = 1,4-bis(1-imidazoly)benzene, have been solvothermally synthesized and structurally characterized by single crystal X-ray diffraction, elemental analysis (EA), thermogravimetric analysis (TGA) and infrared (IR) analysis. The structural analysis showed that 1 should be regarded as a complex 3D structure based on different 1D Cd–(COO) or Cd–(COO)–(COOH) rods as SBUs, and 2 was viewed as a complex 3D framework based on 1D Cd–(COO) rods as SBUs. MOFs 1 and 2 have good stability in boiling water, and alkaline/acidic aqueous solutions (pH = 4–10). The adsorption measurements indicated that the adsorption capacity of 1 for CO2 and CH4 is greater than that of 2, while the adsorption selectivity of 1 for CO2 is superior to that for CH4, which is attributed to the fact that 1 has a larger porosity and CO2 has characteristics such as a linear structure, larger polarizability and significant quadrupole moment. Furthermore, luminescence studies revealed that both 1 and 2 can be used as a highly selective and sensitive sensor for sensing TNP or Fe3+ ions in aqueous solution or soil samples, and the fluorescence quenching mechanism was explored in this work.

High-performance electrocatalysts for the methanol oxidation reaction (MOR) are the key to advance the application of direct methanol fuel cells. Pt-Based electrocatalysts for the MOR are limited due to their high cost, low stability and poor resistance to carbon monoxide (CO) poisoning. The development of non-noble metal-based electrocatalysts for the MOR with high activity and good stability is desired, but it remains a challenge. Herein, we report a simple strategy to prepare nickel nanocrystals embedded in a nitrogen-doped carbon matrix (Ni/N-C composite) by pyrolysis of Ni-coordinated polyaniline-poly(vinyl alcohol) hydrogels. These in situ generated Ni nanocrystals serve as active electrocatalysts for the MOR, while the nitrogen-doped carbon matrix serves as a conductive support to facilitate electron transfer and also to protect the active Ni nanocrystals. The optimal Ni/N-C@500 electrocatalyst shows a high MOR activity of 147 mA cm-2 at 1.66 V vs. the RHE in alkaline methanol solution, which is outstanding among Ni-based MOR electrocatalysts. Ni/N-C@500 also shows better stability than the Pt/C catalyst in the long-term MOR test at high current densities. Upon CO poisoning, Ni/N-C@500 retains 85% of its MOR activity, far exceeding the performance of the Pt/C catalyst (61% retention). Owing to its facile synthesis, outstanding activity and high stability, the Ni/N-C@500 composite is promising as a low-cost, efficient and CO-resistant electrocatalyst for the MOR.

Metal sulfides have been considered to be excellent electrode materials for supercapacitors (SCs) due to their high conductivity and electrochemical activity. Meanwhile, the addition of redox additives to the electrolyte can increase the pseudocapacitance of SCs. Herein, the composite (Cu-CuxS@S-C) of Cu nanocrystals and CuxS embedded in S-doped carbon matrix was prepared through impregnation method followed by high-temperature pyrolysis. The optimal Cu-CuxS@S-C-600 has an extremely high capacitance of 9607 mF cm−2 at 5 mA cm−2 in the alkaline electrolyte with thiourea (TU), which is due to the good conductivity of Cu and CuxS, large crystal plane spacing of CuxS, and the redox reaction caused by the addition of TU. The symmetrical SC based on Cu-CuxS@S-C-600 electrode was fabricated, its pseudocapacitance (960 mF cm−2) in the electrolyte with TU is 4.6 times that (208 mF cm−2) in the electrolyte without TU. The energy density (E) of SC reaches 261 µ Wh cm−2, and the power density (P) is 2800 µW cm−2 at 4 mA cm−2 in the gel electrolyte with TU.

The development of effective and low-cost anode catalysts is a big challenge in the application of direct hydrazine fuel cell (DHFC). Herein, we report the in-situ grown Co9S8 nanocrystals into S-doped carbon matrix (Co9S8@S-C) as an efficient electrocatalyst for hydrazine oxidation reaction (HzOR). Co9S8 nanocrystals serve as the active site for electrocatalytic HzOR, and the conductive and porous S-doped carbon matrix not only promotes the charge and mass transfer, but also immobilizes and protects the Co9S8 nanocrystals from damage during HzOR. The optimal Co9S8@S-C-600 catalyst possesses a high Brunauer-Emmett-Teller (BET) specific surface area of 60.8 m2 g−1, and shows a current density (j) of 376 mA∙cm−2 for HzOR in alkaline medium at 0.3 V vs RHE, whose activity exceeds that of some previously reported electrocatalysts for HzOR. Furthermore, the activity retention rate of Co9S8@S-C-600 is 92.8% after 12-h HzOR test at a j value of greater than 300 mA∙cm−2, which is much better than that of Pt/C catalyst (15% activity retention). The excellent activity and durability of the Co9S8@S-C-600 catalyst are mainly attributed to the combined effect of highly active Co9S8 nanocrystals and the conductive and porous S-doped carbon matrixes, which makes Co9S8@S-C-600 as an effective non-noble metal electrocatalysts for HzOR.

The performance of direct methanol fuel cells (DMFC) mainly depends on the activity and stability of the noble-metal-based anode catalysts for methanol oxidation reaction (MOR), whose broad application is limited by the scarcity of noble metals and their susceptibility to carbon monoxide poisoning. Many efforts have been devoted to the developing of non-noble metal based MOR catalysts. Previous studies have shown that the catalytic properties of noble-metal catalysts can be modified by alloying in nanomaterials. However, non-noble metal-based nanocrystals are rarely studied as electrocatalysts, because of their high susceptibility to air oxidation. Herein, we report a simple strategy to prepare non-noble metal nanocrystals (Cu-Co nanocrystals), which are stabilized in a nitrogen-doped carbon (N-C) matrix to form Cu-Co@N-C composite. Since Co has a high activity for oxidation reactions, and Cu has a high adsorption capacity for methanol, the Cu-Co nanocrystals should present good MOR activity because of the synergistic effect of Cu and Co. The highly active Cu-Co nanocrystals are embedded in a porous N-C matrix with a large specific surface area (127.3 m2/g), which not only protects the Cu-Co nanocrystals, but also facilitate the mass and charge transfer. Indeed, the optimal Cu-Co@N-C catalyst shows a MOR activity of 171.3 mA/cm2 at 0.6 V vs SCE in alkaline medium, which is higher than most of previously reported Cu and Co-based MOR catalysts. The stability and CO-resistance of the optimal Cu-Co@N-C catalyst are also better than that of Pt/C catalyst, enabling Cu-Co@N-C a promising MOR catalyst for broad application of DMFC.

A new marine hazard of golden tides caused by floating brown macroalgae-Sargassum occurred in the Yellow Sea in December 2016. An economic loss of 0.5 billion CNY (about U.S. $73 million) was estimated due to the damaged seaweed aquaculture in the Jiangsu Shoal, China. In this letter, images from the new Chinese satellite of Gaofen (GF) with high-resolution optical cameras are used to retrieve the drifting path of floating Sargassum and its origin. A southward drifting path of floating Sargassum in the western Yellow Sea is identified for the first time, and the initial site of bloom occurrence is near the eastern end of the Shandong Peninsula, China, implying the origin of this hazard of floating Sargassum. The scale of this Sargassum bloom event in the Jiangsu Shoal is also evaluated using a linear-mixing model suitable for high-resolution images. The result shows that the total area of Sargassum-containing pixels in the GF-1 wide-field-of-view images on December 31, 2016 was more than 46 km2, and according to the estimation by the linear-mixing model, the total area of sea surface completely covered by Sargassum was above 8.8 km2. The approach and the results presented in this letter should contribute to the future study and management of golden tides in Chinese coastal waters.

Litter decomposition serves an important role in maintaining nitrogen (N) availability within forest ecosystems. However, the interactive effects of exogenous N, drought, and litter quality and mixing on N immobilization during decomposition remain unclear. The aim of this study was to assess the effects of litter quality, reduced precipitation, N addition, and their interactions on litter mass loss and N immobilization. This field study analyzed the effects of N addition and decreased precipitation on the decomposition rates and associated N immobilization of four types of litter: Quercus mongolica (QM), Tilia amurensis (TA), Pinus koraiensis (PK), and a mixture (MIX) of all three. The chemical quality of the MIX was prepared in a 4:3:3 (mass) ratio of PK, TA, and QM litters. Litterbags were placed in an N addition and precipitation manipulation forest field and collected after 92, 154, 365, 457, and 874 days. Decomposing litter residues were characterized for mass loss and N content to assess N immobilization. The addition of N had no significant effect on litter decomposition under both precipitation conditions, but a reduction in precipitation significantly depressed litter decomposition. The increases in N immobilization with N addition depended on the litter type and decomposition period. Precipitation reduction had significant effects on N immobilization and enhanced the magnitude and duration of N immobilization in decomposing litter, and both of which can be increased by N addition. The results indicate that the litter species is the major regulator that controls mass loss and N immobilization. Furthermore, the MIX treatment did not show non-additive effects on mass loss but did exhibit some weak synergistic effects on N immobilization. Our results suggest that decomposing litters could help to sequester N depending on the litter identity and water regime in temperate forest ecosystems.

A lanthanide coordination polymer [Eu(BCPB)(H2O)2]n (1) was synthesized based on a semirigid tripodal polycarboxylic acid ligand (H3BCPB = 3,5-bis(2-carboxy-phenoxy)-benzoic acid). Single crystal X-ray diffraction analyses showed that compound 1 exhibits 2D layer structures with [Eu6(COO)22(H2O)12] SBU. Furthermore, fluorescence tests demonstrated that 1 has highly sensitive detection for Fe3+/Cr2O72− ions in aqueous solution by a fluorescence quenching effect. Meanwhile, the quenching mechanisms of 1 for Fe3+ and Cr2O72− were also investigated in detail.

A novel nanoflower microsphere Zn-MOF has been solvothermally synthesized. By virtue of the large porosity and specific surface area of Zn-MOF, Ce salts have been successfully incorporated into the cavity of Zn-MOF to fabricate bimetallic Ce@Zn-MOF composites, which were covered in glassy carbon electrode (GCE) as sensors for the efficient recognition of uric acid (UA). The electrochemical behaviors of Zn-MOF and Ce@Zn-MOF-based sensor for UA were analyzed by cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPV). The results showed that the Ce@Zn-MOF/GCE-based sensor exhibited sensitive identification ability for UA in phosphate buffered saline (PBS) solution (pH = 7.0) with a low detection limit (DL) of 0.51 ng in the recognition range of 0–300 ng mL−1. The results were attributed to that the introduction of Ce ions improved the charge conduction ability of Ce@Zn-MOF, thus enhancing the recognition sensitivity of Ce@Zn-MOF for UA, which can also be verified by theoretical calculation. In addition, Ce@Zn-MOF showed good stability, which can be ascribed to the bonding interaction between Ce ions and C/O atoms in Zn-MOF. Meanwhile, the Ce@Zn-MOF based sensor also exhibited high reproducibility and anti-interference ability for recognition of UA. In this work, the reasonable design of Ce@Zn-MOF based sensor provides a suitable platform for UA sensing rapidly and sensitively.

The key problem to be solved for the large-scale commercial application of direct urea fuel cells (DUFCs) is to develop a highly efficient catalyst for urea oxidation reaction (UOR). Some drawbacks such as scarcity and poor catalytic performance limit the application of noble metal-based catalysts in the oxidation of urea, it is particularly necessary to design and synthesize non-noble metal-based catalysts with good catalytic performance. In this work, we have fabricated Ni-based composites (Ni/NiO-N-C) through the pyrolysis of the precursor Ni(OH)2@PPH (polyaniline-polyvinyl alcohol hydrogels). The optimal Ni/NiO-N-C-500 catalyst displays an excellent activity of 182 mA cm−2 at 0.6 V vs SCE for UOR in alkaline media. Meanwhile, Ni/NiO-N-C-500 also indicates excellent stability after 1000 cycling CV tests (81% capacitance retention), which is attributed to the synergy between Ni/NiO nanocrystalline active centers and nitrogen-doped carbon substrate, that is, N-doped carbon layers improve the surface electron density and the electrical conductivity of the composite catalyst, thus leading to the improvement of the catalytic activity of catalyst. On account of its easy synthesis, high activity and good durability, the Ni/NiO-N-C-500 catalyst has the potential to act as a good alternative material for precious metal-based catalysts in DUFCs.

The development of active, stable and poison-resistant electrocatalysts for methanol oxidation reaction (MOR) has become a key challenge to improve the performance of direct methanol fuel cells (DMFCs). Herein, we report a simple strategy to prepare cobalt nanoscrystal/nitrogen-doped carbon (Co/N-C) composites as efficient and carbon monoxide (CO) resistant electrocatalysts for MOR. The Co/N-C composites are synthesized by the pyrolysis of porous CoCl2-polyaniline hydrogels. While CoCl2 is reduced to Co nanocrystals as active electrocatalyst for MOR, the polyaniline hydrogel is pyrolyzed to porous layered N-doped carbon that immobilize and protect Co nanocrystals, and also facilitate the mass and charge transfer through the electrolyte and electrode. After systematically exploring the preparation conditions of Co/N-C composites, we have found the optimal Co/N-C-1-500 (pyrolyzed at 500 °C) can achieve a high current density of 231 mA∙cm−2 at 0.8 V vs SCE for MOR in alkaline media. Meanwhile, the Co/N-C-1-500 catalyst presents a good durability and a high resistance to CO poisoning (93.5% retention of MOR activity), superior to the performance of Pt/C catalysts. With its high activity, good stability and superior resistance to CO poisoning, Co/N-C-1-500 is promising as a low-cost and efficient anode catalyst for DMFCs.

Purpose Little is known about the interactive effects of temperature, nitrogen (N) supply, litter quality, and decomposition time on the turnover of carbon (C) and N of forest litter. The objective of this study was to investigate the interactive effects of warming, N addition and tree species on the turnover of C and N during the early decomposition stage of litters in a temperate forest.