Mixing of pine and arbuscular mycorrhizal tree species changed soil organic carbon storage by affecting soil microbial characteristics.

Pure and mixed pine forests are found all over the world. The mycorrhizal type affects soil microbial activity and carbon sequestration capacity in pure forests. However, the effects of mycorrhizal type on microbial characteristics and carbon sequestration capacity in pine mixed forests remain untested. Further, making it difficult to predict carbon storage of the conversion from pure pine forests to mixed forests at larger scales. Herein, a meta-analysis showed that the contents of soil microbial biomass, mineral-associated organic carbon, and soil organic carbon in pine mixed forests with introduced arbuscular mycorrhizal tree species (PMAM) increased by 26.41 %, 58.55 %, and 27.41 %, respectively, compared to pure pine forests, whereas those of pine mixed forests without arbuscular mycorrhizal tree species (PMEcM) remained unchanged. Furthermore, the effect size of microbial biomass, mineral-associated organic carbon and organic carbon contents in subsoil of PMAM are 56.48 %, 78.49 % and 43.05 %, respectively, which are higher than those in topsoil. The improvement of carbon sinks throughout the PMAM soil profile is positively correlated with increases in microbial biomass and mineral-associated organic carbon in subsoil, according to regression analysis and structural equation modelling. In summary, these results highlight that the positive effects of introducing arbuscular mycorrhizal tree species rather than ectomycorrhizal tree species into pure pine forests on soil microbial biomass and carbon sequestration. The positive link between microbial biomass, mineral-associated organic carbon, and soil organic carbon suggests an underlying mechanism for how soil microorganisms store carbon in pine mixed forests. Nevertheless, our findings also imply that the soil carbon pool of PMAM may be vulnerable under climate change. Based on the above findings, we propose that incorporating mycorrhizal type of tree species and soil thickness into mixed forests management and biodiversity conservation.

Co-applied biochar and PGPB promote maize growth and reduce CO2 emission by modifying microbial communities in coal mining degraded soils.

Coal mining is one of the human activities that has the greatest impact on the global carbon (C) cycle and biodiversity. Biochar and plant growth-promoting bacteria (PGPB) have been both used to improve coal mining degraded soils; however, it is uncertain whether the effects of biochar application on soil respiration and microbial communities are influenced by the presence or absence of PGPB and soil nitrogen (N) level in coal mining degraded soils. A pot experiment was carried out to examine whether the effects of biochar addition (0, 1, 2 and 4% of soil mass) on soil properties, soil respiration, maize growth, and microbial communities were altered by the presence or absence of PGPB (i.e. Sphingobium yanoikuyae BJ1) (0, 200 mL suspension (2 × 106 colony forming unit (CFU) mL-1)) and two soil N levels (N0 and N1 at 0 and 0.2 g kg-1 urea- N, respectively). The results showed the presence of BJ1 enhanced the maize biomass relative to the absence of BJ1, particularly in N1 soils, which was related to the discovery of Lysobacter and Nocardioides that favor plant growth in N1 soils. This indicates a conversion in soil microbial communities to beneficial ones. The application of biochar at a rate of 1% decreased the cumulative CO2 regardless of the presence or absence of BJ1; BJ1 increased the ß-glucosidase (BG) activities, and BG activities were also positively correlated with RB41 strain with high C turnover in N1 soils, which indicates that the presence of BJ1 improves the C utilization rates of RB41, decreasing soil C mineralization. Our results highlight that biochar addition provided environmental benefits in degraded coal mining soils, and the direction and magnitude of these effects are highly dependent on the presence of PGPB and the soil N level.

Accurate Measurements of NH3 Differential Adsorption Heat Unveil Structural Sensitivity of Brønsted Acid and Brønsted/Lewis Acid Synergy in Zeolites.

Differential adsorption heats of NH3 on a series of zeolites, including MOR, MFI, FER, and BEA, are accurately measured to probe their acidity using flow-pulse adsorption microcalorimetry. Initial adsorption heats of NH3 at Brønsted acid sites (BAS) vary between 105 to 136 kJ/mol, depending on framework aluminum amounts and topography structures of zeolites. A Brønsted/Lewis acid synergy between BAS and proximate tricoordinated framework-associated aluminum species is identified to generate super acid sites with initial adsorption heats of NH3 around 150 kJ/mol, but occurs only in the MFI zeolites and sensitively depends on the Si/Al ratio. These accurate data of NH3 differential adsorption heats unveil structural sensitivity of BAS and Brønsted/Lewis acid synergy in zeolites and provide experimental benchmark data for fundamental understanding of acidity and acid-catalysis of zeolites.

Unsaturated Penta-Coordinated Mo5c5+ Sites Enabled Low-Temperature Oxidation of C-H Bonds in Ethers.

Selective oxidation of C-H bonds under mild conditions is one of the most important and challenging issues in utilization of energy-related molecules. Molybdenum oxide nanostructures containing Mo5+ species are effective for these reactions, but the accurate identification of the structure of active Mo5+ species and the catalytic mechanism remain unclear. Herein, unsaturated penta-coordinated Mo5c5+ with a high fraction in MoOx fabricated by the hydrothermal method were identified as the active sites for low-temperature oxidation of dimethyl ether (DME) by the deep correlation of characterizations, density functional theory calculations, and activity results, giving a methyl formate selectivity of 96.3% and DME conversion of 12.5% at unreported 110 °C. Low-temperature electron spin resonance (ESR) and quasi in situ X-ray photoelectron spectra (XPS) with the designed experiments confirm that the Mo5c5+ species can be formed in situ. Molybdenum located at the pentachronic site is preferable to significantly promote the oxidation of the C-H bond in CH3O* at lower temperatures.

Tree species identity and mixing ratio affected the release of several metallic elements from mixed litter in coniferous-broadleaf plantations in subtropical China.

Planting broadleaf trees in coniferous forests has been shown to promote biogeochemical cycling in plantations; however, how species mixing influences litter decomposition and release of metallic elements from mixed coniferous-broadleaf litter remains unclear. An in situ litter decomposition experiment was conducted to examine the effect of 1) a mixture from coniferous litter (Pinus massoniana) with different individual broadleaved litter (Bretschneidera sinensis, Manglietia chingii, Cercidiphyllum japonicum, Michelia maudiae, Camellia oleifera) and 2) their mixing ratio (mass ratios of coniferous and broadleaf litter of 5:5, 6:4 and 7:3) on the release of metallic elements [calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), manganese (Mn), iron (Fe), copper (Cu) and zinc (Zn)] during litter decomposition. We found that the identity of the broadleaf tree species in the mixed litter and the mixing ratio affected the release rates of metallic elements (p < 0.05). After one year of decomposition, K, Mg, Mn and Zn were released, while Na, Ca, Fe and Cu accumulated in the mixed litter. Mixing increased the release of K, Ca, Na, Mg, Fe, Mn, Cu and Zn in more than one-third of the samples, but inhibited the release of K, Fe and Mn in less than 14% of the samples. Increasing the mixing ratio of coniferous to broadleaf litter enhanced the release of Na, Fe, Mn and Zn but decreased the release of Ca and Mg. Overall, these results highlight that mixed litter, particularly tree species identity and mixing ratio, can alter the release and enrichment of metallic elements during litter decomposition, thereby affecting the cycling of metallic elements in plantations with different species compositions.

Physiological mechanisms of the tolerance response to manganese stress exhibited by Pinus massoniana, a candidate plant for the phytoremediation of Mn-contaminated soil.

Manganese (Mn) pollution in soil, especially around mining areas, is a serious environmental problem worldwide. Generally, plant remediation technology needs to select species with high Mn tolerance, and exploring the Mn tolerance mechanism of tree species with high ecological and economic benefits is of considerable significance for the effective identification and efficient utilization of Mn phytoremediation species. Masson pine (Pinus massoniana) is one of the main afforestation tree species, exhibiting high ecological and economic value in subtropical areas and also a plant with high Mn accumulation. To reveal the mechanisms governing the tolerance of this species for Mn stress, the morphological, physiological, and biochemical responses of seedlings grown in sand cultures under different Mn stress (0.0009~30 mmol·L-1) were analyzed. The results showed that despite the chlorosis of leaves under high Mn stress (30 mmol·L-1), the height of plant seedling, the diameter of ground and the root morphology was not significantly inhibited (p < 0.05), and a high level of Mn accumulated (translocation factor = 1.10). With increasing Mn concentration, malondialdehyde (MDA), soluble protein, and soluble sugar increased, and superoxide dismutase (SOD) and catalase (CAT) increased at first and later decreased. Under Mn stress, net photosynthetic rate, transpiration rate, stomatal conductance, total chlorophyll, chlorophyll a, and carotenoids increased first and subsequently decreased, and intercellular CO2 concentration and chlorophyll b decreased, but chlorophyll fluorescence characteristics did not change significantly. Taken together, these results indicate that Masson pine can tolerate Mn stress by increasing its antioxidant enzyme activity and non-enzyme metabolite content. In addition, Masson pine can maintain photosynthesis by changing its gas exchange parameters, photosynthetic pigment content, and chlorophyll fluorescence, which is another important mechanism for coping with high Mn concentrations in the environment. In conclusion, the above results show that Masson pine can be effectively used for phytoremediation of Mn-contaminated soil.

Oxidative Strong Metal-Support Interactions between Metals and Inert Boron Nitride.

The strong metal-support interaction (SMSI) is one of the most important concepts in heterogeneous catalysis, which has been widely investigated between metals and active oxides triggered by reductive atmospheres. Here, we report the oxidative strong metal-support interaction (O-SMSI) effect between Pt nanoparticles (NPs) and inert hexagonal boron nitride (h-BN) sheets, in which Pt NPs are encapsulated by oxidized boron (BOx) overlayers derived from the h-BN support under oxidative conditions. De-encapsulation of Pt NPs has been achieved by washing in water, and the residual ultrathin BOx overlayers work synergistically with surface Pt sites for enhancing CO oxidation reaction. The O-SMSI effect is also present in other h-BN-supported metal catalysts such as Au, Rh, Ru, and Ir within different oxidative atmospheres including O2 and CO2, which is determined by metal-boron interaction and O affinity of metals.

Reaction-Induced Strong Metal-Support Interactions between Metals and Inert Boron Nitride Nanosheets.

Encapsulation of metal nanocatalysts by support-derived materials is well known as a classical strong metal-support interaction (SMSI) effect that occurs almost exclusively with active oxide supports and often blocks metal-catalyzed surface reactions. In the present work this classical SMSI process has been surprisingly observed between metal nanoparticles, e.g., Ni, Fe, Co, and Ru, and inert hexagonal boron nitride (h-BN) nanosheets. We find that weak oxidizing gases such as CO2 and H2O induce the encapsulation of nickel (Ni) nanoparticles by ultrathin boron oxide (BOx) overlayers derived from the h-BN support (Ni@BOx/h-BN) during the dry reforming of methane (DRM) reaction. In-situ surface characterization and theory calculations reveal that surface B-O and B-OH sites in the formed BOx encapsulation overlayers work synergistically with surface Ni sites to promote the DRM process rather than blocking the surface reactions.

Mesoporous Rh Emerging from Nanophase-separated Rh-Y Alloy.

Mesoporous precious metals with abundant active sites and high surface area have been widely recognized as high-performance catalytic materials. However, the templated synthesis is complex and costly. Herein, we report a mesoporous rhodium (m-Rh) that can be readily synthesized from entangled nanofibres of Rh and Y2 O3 without templates. The entangled nanofibres, prepared from uniform Rh-Y alloys under redox atmosphere, were the key precursor in the synthesis processes. Moreover, the m-Rh efficiently catalyzed carbon dioxide reforming of methane (DRM) at a low reaction temperature of 683 K. Further, electrochemical methods of CO electro-oxidation were innovatively used to demonstrate the stability of CO and oxygen species for the DRM reaction.

Comparison of molecular mechanisms of rheumatoid arthritis and osteoarthritis using gene microarrays.

The present study aimed to compare the molecular mechanisms of rheumatoid arthritis (RA) and osteoarthritis (OA). The microarray dataset no. GSE29746 was downloaded from Gene Expression Omnibus. After data pre­processing, differential expression analysis between the RA group and the control, as well as between the OA group and the control was performed using the LIMMA package in R and differentially expressed transcripts (DETs) with |log2fold change (FC)|>1 and P<0.01 were identified. DETs screened from each disease group were then subjected to functional annotation using DAVID. Next, DETs from each group were used to construct individual interaction networks using the BIND database, followed by sub­network mining using clusterONE. Significant functions of nodes in each sub­network were also investigated. In total, 19 and 281 DETs were screened from the RA and OA groups, respectively, with only six common DETs. DETs from the RA and OA groups were enriched in 8 and 130 gene ontology (GO) terms, respectively, with four common GO terms, of which to were associated with phospholipase C (PLC) activity. In addition, DETs screened from the OA group were enriched in immune response­associated GO terms, and those screened from the RA group were largely associated with biological processes linked with the cell cycle and chromosomes. Genes involved in PLC activity and its regulation were indicated to be altered in RA as well as in OA. Alterations in the expression of cell cycle­associated genes were indicated to be linked with the occurrence of OA, while genes participating in the immune response were involved in the occurrence of RA.