Afforestation has been proposed as an effective method of carbon (C) sequestration; however, the magnitude and direction of soil carbon accumulation following afforestation and its regulation by soil ...nitrogen (N) dynamics are still not well understood.
We synthesized the results from 292 sites and carried out a meta-analysis to evaluate the dynamics of soil C and N stocks following afforestation.
Changes in soil C and N stocks were significantly correlated and had a similar temporal pattern. Significant C and N stock increases were found 30 and 50 yr after afforestation, respectively. Before these time points, C and N stocks were either depleted or unchanged. Carbon stock increased following afforestation on cropland and pasture, and in tropical, subtropical and boreal zones. The soil N stock increased in the subtropical zone. The soil C stock increased after afforestation with hardwoods such as Eucalyptus, but did not change after afforestation with softwoods such as pine. Soil N stocks increased and decreased, respectively, after afforestation with hardwoods (excluding Eucalyptus) and pine.
These results indicate that soil C and N stocks both increase with time after afforestation, and that C sequestration through afforestation depends on prior land use, climate and the tree species planted.
Soil micro‐organisms play a key role in soil biogeochemical cycles, but their growth and activities are often limited by resource availability. Understanding soil processes that are driven by ...micro‐organisms and resource limitation of microbes will help to elucidate controls on soil fertility and improve the ability to predict the responses of an ecosystem to global changes. As a widespread ecosystem type, karst ecosystem develops from limestone or dolomite with unique soil; however, karst ecosystems remain poorly understood regarding their soil microbial processes and microbial resource limitation.
Here, ecoenzymatic stoichiometry was used as an indicator of microbial resource limitation, and to model major microbial processes (i.e. decomposition of soil organic carbon and microbial respiration) in a karst and a non‐karst forest.
Results showed that the modelled decomposition and respiration rates were significantly higher in the karst forest than in the non‐karst forest. In addition, results of ecoenzymatic stoichiometry showed that the karst forest was more carbon‐limited than the non‐karst forest. In contrast, the karst forest was likely saturated with nitrogen, but the non‐karst forest was limited by nitrogen. Both the karst and non‐karst forests were limited by phosphorus, but phosphorus deficiency was more evident in the non‐karst forest than in the karst forest.
These findings highlight the specific profiles of karst ecosystems, and they suggest that the responses of karst ecosystems to global changes should be very different compared to other ecosystems.
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Sn-based materials have attracted much attention as anodes in lithium ion batteries (LIBs) due to their low cost, high theoretical capacities, and high energy density. However, their practical ...applications are limited by the poor cydability originating from the huge volume changes. Graphene nanosheets (GNSs), a novel two-dimensional carbon sheet with one atom thickness and one of the thinnest materials, significantly address the challenges of Sn-based anodes as excellent buffering materials, showing great research interests in UBs. In this review, various nanocomposites of GNSs/Sn-based anodes are summarized in detail, including binary and ternary composites. The significant impact of 2D GNSs on the volume change of Sn-based anodes during cycling is discussed, along with with their preparation methods, properties and enhanced LIB performance.
Mixed transition‐metal oxides (MTMOs), including stannates, ferrites, cobaltates, and nickelates, have attracted increased attention in the application of high performance lithium‐ion batteries. ...Compared with traditional metal oxides, MTMOs exhibit enormous potential as electrode materials in lithium‐ion batteries originating from higher reversible capacity, better structural stability, and high electronic conductivity. Recent advancements in the rational design of novel MTMO micro/nanostructures for lithium‐ion battery anodes are summarized and their energy storage mechanism is compared to transition‐metal oxide anodes. In particular, the significant effects of the MTMO morphology, micro/nanostructure, and crystallinity on battery performance are highlighted. Furthermore, the future trends and prospects, as well as potential problems, are presented to further develop advanced MTMO anodes for more promising and large‐scale commercial applications of lithium‐ion batteries.
Mixed transition‐metal oxides (MTMOs), including stannates, ferrites, cobaltates, and nickelates, have attracted increasing attention in the application of high performance lithium‐ion batteries. The rational design, energy storage mechanism and the future trends and prospects of novel MTMOs are discussed in detail. It is believed that MTMOs with higher reversible capacity, better structural stability, and high electronic conductivity are some of the most promising candidates for anodes for lithium ion batteries.
Porous NiO architecture has been successfully prepared by calcining a novel Ni-MOF in air. As revealed by XRD, SEM and TEM, the obtained NiO architecture is assembled from two-dimensional nanosheets, ...which primarily consist of uniform nanoparticles and large quantities of pores between nanoparticles. Electrochemical data present that the NiO architecture possesses a reversible specific capacitance of 324Fg−1 after 1000 cycles at 1Ag−1, and nearly 46% capacity retention when the current density increases from 1 to 40Ag−1, suggesting its promising application in supercapacitors.
Porous NiO architecture derived from a novel Ni-MOF exhibits enhanced electrochemical performances used as an electrode material for supercapacitors. Display omitted
•The synthesis based on one-step annealing of a novel Ni-MOF is facile and scalable.•The NiO reveals unique porous architecture primarily composed of nanoparticles.•The NiO architecture exhibits excellent capacitive performances.
LiNi0.6Co0.2Mn0.2O2 (NCM) is a highly potential cathode material for lithium-ion batteries (LIBs). However, its poor rate capability and cycling performance at high cutoff voltages have seriously ...hindered further commercialization. In this study, we successfully design an ultra-thin lithium aluminum oxide (LiAlO2) coating on NCM for LIBs. Compared to Al2O3, the utilization of lithium-ion conducting LiAlO2 significantly improves the NCM performance at high cutoff voltages of 4.5/4.7V. The study reveals that the LiAlO2-coated NCM can maintain a reversible capacity of more than 149mAhg−1 after 350 cycles with 0.078% decay per cycle. Furthermore, LiAlO2-coated NCM exhibits higher rate capacities 206.8mAhg−1 at 0.2C (50mAg−1) and 142mAhg−1 at 3C than the Al2O3-coated NCM (196.9mAhg−1 at 0.2C and 131.9mAhg−1 at 3C). Our study demonstrates that the ultra-thin LiAlO2 coating is superior to Al2O3 and significantly improves the capacity retention and rate capability of NCM for LIBs.
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•The ultra-thin Al2O3 and LiAlO2 coatings were successfully designed onto NCM.•The optimized coating prevents the cathode from reacting with the electrolyte.•The optimized coating benefits lithium ion transfer upon cycling.•The LiAlO2 coating was more effective in improving NCM performance than Al2O3.
Cropland soil is an important source of atmospheric nitric oxide (NO) and ammonia (NH3). Chinese croplands are characterized by intensive management, but limited information is available with regard ...to NO emissions from croplands in China and NH3 emissions in south China. In this study, a mesocosm experiment was conducted to measure NO and NH3 emissions from a typical vegetable-land soil in the Pearl River Delta following the applications of 150 kg N ha(-1) as urea, ammonium nitrate (AN) and ammonium bicarbonate (ABC), respectively. Over the sampling period after fertilization (72 days for NO and 39 days for NH3), mean NO fluxes (± standard error of three replicates) in the control and urea, AN and ABC fertilized mesocosms were 10.9±0.9, 73.1±2.9, 63.9±1.8 and 66.0±4.0 ng N m(-2) s(-1), respectively; mean NH3 fluxes were 8.9±0.2, 493.6±4.4, 144.8±0.1 and 684.7±8.4 ng N m(-2) s(-1), respectively. The fertilizer-induced NO emission factors for urea, AN and ABC were 2.6±0.1%, 2.2±0.1% and 2.3±0.2%, respectively. The fertilizer-induced NH3 emission factors for the three fertilizers were 10.9±0.2%, 3.1±0.1% and 15.2±0.4%, respectively. From the perspective of air quality protection, it would be better to increase the proportion of AN application due to its lower emission factors for both NO and NH3.
In rubber tree, bark is one of important agricultural and biological organs. However, the molecular mechanism involved in the bark formation and development in rubber tree remains largely unknown, ...which is at least partially due to lack of bark transcriptomic and genomic information. Therefore, it is necessary to carried out high-throughput transcriptome sequencing of rubber tree bark to generate enormous transcript sequences for the functional characterization and molecular marker development.
In this study, more than 30 million sequencing reads were generated using Illumina paired-end sequencing technology. In total, 22,756 unigenes with an average length of 485 bp were obtained with de novo assembly. The similarity search indicated that 16,520 and 12,558 unigenes showed significant similarities to known proteins from NCBI non-redundant and Swissprot protein databases, respectively. Among these annotated unigenes, 6,867 and 5,559 unigenes were separately assigned to Gene Ontology (GO) and Clusters of Orthologous Group (COG). When 22,756 unigenes searched against the Kyoto Encyclopedia of Genes and Genomes Pathway (KEGG) database, 12,097 unigenes were assigned to 5 main categories including 123 KEGG pathways. Among the main KEGG categories, metabolism was the biggest category (9,043, 74.75%), suggesting the active metabolic processes in rubber tree bark. In addition, a total of 39,257 EST-SSRs were identified from 22,756 unigenes, and the characterizations of EST-SSRs were further analyzed in rubber tree. 110 potential marker sites were randomly selected to validate the assembly quality and develop EST-SSR markers. Among 13 Hevea germplasms, PCR success rate and polymorphism rate of 110 markers were separately 96.36% and 55.45% in this study.
By assembling and analyzing de novo transcriptome sequencing data, we reported the comprehensive functional characterization of rubber tree bark. This research generated a substantial fraction of rubber tree transcriptome sequences, which were very useful resources for gene annotation and discovery, molecular markers development, genome assembly and annotation, and microarrays development in rubber tree. The EST-SSR markers identified and developed in this study will facilitate marker-assisted selection breeding in rubber tree. Moreover, this study also supported that transcriptome analysis based on Illumina paired-end sequencing is a powerful tool for transcriptome characterization and molecular marker development in non-model species, especially those with large and complex genomes.
This study was aimed to investigate the direction and magnitude of soil organic carbon (SOC) dynamics and the underlying mechanisms following agricultural abandonment in a subtropical karst area, ...southwest China. Two post-agriculture succession sequences including grassland (~10 years), shrubland (~29 years), secondary forest (~59 years) and primary forest with cropland as reference were selected. SOC and other soil physicochemical variables in the soil depth of 0-15 cm (representing the average soil depth of the slope in the studied area) were measured. SOC content in the grassland was not significantly elevated relative to the cropland (42.0 ± 7.3 Mg C ha
). SOC content in the shrubland reached the level of the primary forest. On average, SOC content for the forest was 92.6 ± 4.2 Mg C ha
, representing an increase of 120.4 ± 10.0% or 50.6 ± 4.2 Mg ha
relative to the cropland. Following agricultural abandonment, SOC recovered to the primary forest level in about 40 years with a rate of 1.38 Mg C ha
yr
. Exchangeable Ca and Mg were found to be the strongest predictors of SOC dynamics. Our results suggest that SOC content may recover rapidly following agricultural abandonment in the karst region of southwest China.
Titanium alloy (Ti-6Al-4V) has been extensively applied in joint replacements, orthopedic prostheses, dental implants, and so on, because of their good biocompatibilities and mechanical properties. ...However, the inferior antibacterial activity and biological inert of titanium alloy limit its application in the field of hard tissue repair. Therefore, the surface modification to Ti-6Al-4V is well method. In this paper, titanium nitride (TiN) was first deposited on the surface of Ti-6Al-4V alloy. Then magnesium (Mg) and silver (Ag) ions with different ratios (Mg:Ag = 0.5:1; 1:1; 3:1) were implanted into TiN via a plasma immersion ion implantation (PIII) system to explore the effects of Mg/Ag ratios on the cell adhesion and the preliminary antibacterial properties. Structure characteristics and compositions of Mg/Ag implanted TiN were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). X-ray photoelectron spectrometer (XPS) proved the presence of Mg and Ag on the surface of Mg/Ag-TiN. The results of water contact angle and protein adsorption proved that the wettability and protein adsorption energy of the materials increased significantly with the increase of Mg content. Moreover, in vitro investigations indicated that Mg/Ag (1/1)-TiN exhibited the best cell adhesion and spreading activity, and ideal proliferation, as well as preliminary antibacterial activities, which made it has a good application prospect in orthopedic material.
The flow chart of experiments Display omitted
•Different contents of Mg and Ag were implanted into the TiN coated Ti-6Al-4V.•Mg is positive for protein absorption, cell adhesion and proliferation.•Ag possesses better antibacterial effect within a certain range.•Proper Ag and Mg contents can promote biological and antibacterial properties.
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