Biochar application to soils may increase carbon (C) sequestration due to the inputs of recalcitrant organic C. However, the effects of biochar application on the soil greenhouse gases (GHGs) fluxes appear variable among many case studies; therefore the efficacy of biochar as a carbon sequestration agent for climate change mitigation remains uncertain. We performed a meta-analysis of 91 published papers with 552 paired comparisons to obtain a central tendency of three main GHG fluxes (i.e., CO 2 , CH 4 , and N 2 O) in response to biochar application. Our results showed that biochar application significantly increased soil CO 2 fluxes by 22.14%, but decreased N 2 O fluxes by 30.92% and did not affect CH 4 fluxes. As a consequence, biochar application may significantly contribute to increased global warming potential (GWP) of total soil GHG fluxes due to the large stimulation of CO 2 fluxes. However, soil CO 2 fluxes were suppressed when biochar was added to fertilized soils, indicating that Accepted ArticleThis article is protected by copyright. All rights reserved. biochar application is unlikely to stimulate CO 2 fluxes in the agriculture sector, in which N fertilizer inputs are common. Responses of soil GHG fluxes mainly varied with biochar feedstock source and soil texture, and the pyrolysis temperature of biochar. Soil and biochar pH, biochar applied rate and latitude also influence soil GHG fluxes, but to a more limited extent.Our findings provide a scientific basis for developing more rational strategies towards widespread adoption of biochar as a soil amendment for climate change mitigation.

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Shotgun proteome analysis platforms based on multidimensional liquid chromatography-tandem mass spectrometry (LC-MS/MS) provide a powerful means to discover biomarker candidates in tissue specimens. Analysis platforms must balance sensitivity for peptide detection, reproducibility of detected peptide inventories and analytical throughput for protein amounts commonly present in tissue biospecimens (<100 µg), such that platform stability is sufficient to detect modest changes in complex proteomes. We compared shotgun proteomics platforms by analyzing tryptic digests of whole cell and tissue proteomes using strong cation exchange (SCX) and isoelectric focusing (IEF) separations of peptides prior to LC-MS/MS analysis on a LTQ-Orbitrap hybrid instrument. IEF separations provided superior reproducibility and resolution for peptide fractionation from samples corresponding to both large (100 µg) and small (10 µg) protein inputs. SCX generated more peptide and protein identifications than did IEF with small (10 µg) samples, whereas the two platforms yielded similar numbers of identifications with large (100 µg) samples. In nine replicate analyses of tryptic peptides from 50 µg colon adenocarcinoma protein, overlap in protein detection by the two platforms was 77% of all proteins detected by both methods combined. IEF more quickly approached maximal detection, with 90% of IEF-detectable medium abundance proteins (those detected with a total of 3-4 peptides) detected within three replicate analyses. In contrast, the SCX platform required six replicates to detect 90% of SCX-detectable medium abundance proteins. High reproducibility and efficient resolution of IEF peptide separations make the IEF platform superior to the SCX platform for biomarker discovery via shotgun proteomic analyses of tissue specimens.

Accurate determination of protein molecular mass to within 1 Da would be a boon to protein characterization. It would then become possible to (a) count the number of disulfide bridges (-S-S-is 2 Da lighter than 2 -SH); (b) identify deamidation (-NH 2 is 1 Da lighter than -OH); (c) identify such post-translational modifications as phosphorylation and glycosylation; (d) resolve and identify adducts; (e) identify variant amino acid sequences; etc. Determination of the molecular mass of a neutral protein to within 1 Da from measurement of the mass of its gas-phase ion might appear easy. After all, electrospray ionization can now routinely generate abundant multiply-charged gas-phase unhydrated quasimolecular ions, (M + nH) n+ , for most proteins, 1,2 and Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry 3-7 can determine the ion mass to parts-per-million accuracy at typical electrosprayed protein multiply-charged ion mass-to-charge ratios, 500 e m/z e 2000. 8 However, the monoisotopic mass (see below) of a protein inferred from the mass(es) of its corresponding ions may still be wrong by up to several Dalton! There are three stages in the determination of the molecular weight of a neutral protein from its electrosprayed ion mass spectrum. 9 (Our electrospray FT-ICR mass spectra were obtained with a homebuilt instrument operating at 9.4 T, as described elsewhere. 10 ) First, electrospray ionization produces protein ions with various numbers of attached protons and thus several charge states. The first stage in protein mass analysis is therefore to separate the individual charge states (e.g., (M + zH) z+ , (M + (z+1)H) (z+1)+ , etc.). Second, since mass spectrometry reports mass-to-charge ratio, it is necessary to determine the ion charge in order to determine its mass. The massto-charge ratio spectrum of a protein of a given charge state exhibits numerous "isotopic" peaks (see below) spaced ∼1 Da apart (Figure 1). High-resolution FT-ICR mass spectrometry can resolve those peaks for proteins of molecular mass up to more than 100 000 Da, so that the charge state, z, may be determined simply as the reciprocal of the separation between two adjacent isotopic peaks differing in mass by ∼1 Da. 11 However, protein mass measurement accuracy is presently limited by the third stage of mass analysis: namely, knowledge of the isotopic composition (i.e., the constituent chemical formula(s) composing each mass spectral peak). For organic molecules of less than ∼1000 Da, determination of molecular weight from the singly-charged molecular (M + ) or quasimolecular (e.g., (M + H) + ) ion is relatively simple. Why then is it so much more difficult to determine the mass of a biological macromolecule? The problem is apparent from Figure 1 (top). The natural abundance of 13 C is 1.066-1.106% relative to 12 C as 100%. 8 However, for a molecule containing n carbons, the isotopic distribution is a binomial expansion (0.9889 + 0.0111) n , and it is ∼n% as likely that a given molecule will contain one 13 C as that all of the c...

The experiment of dielectric barrier discharge in a 2mm air gap shows that the pressure range of a uniform discharge using polytetrafluoroethylene as barrier is much wider than that using quartz or alumina. The parameters of the charge trapped on the surface of these three dielectric barriers were obtained by surface charge measurement and thermally stimulated current measurement. It was found that surface charge trapping has much influence on the uniform discharge, i.e., the seed electrons necessary for uniform discharge may be produced by the desorption of the absorbed electrons in the shallow trap with energy level lower than 1eV.

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Abstract. Light inside a canopy constantly fluctuates. Under fluctuating light (FL) conditions, stomatal conductance and photosynthetic rate constantly change. In this study, we explored whether this dynamics of stomata movements upon FL influenced the water use efficiency of rice in the field. We used a USDA-curated rice mini-core diversity panel consisting of 204 worldwide distributed accessions. A priori model on dynamic stomatal response to FL was utilised to identify kinetic parameters describing the stomatal delays during the closing (t cl ) and the opening (t op ) phase. Result showed that t cl had a larger variation than t op across the mini-core panel. t cl was negatively correlated with water use efficiency (WUE) related traits, stem diameter, grain weight per tiller and heading time, but positively correlated with maximum annual temperature, carbon assimilation related traits and biomass (P < 0.05). We further showed a strong correlation of t cl with the relative decrease of biomass under drought in 14 accessions with different t cl . We discussed the adjustment of stomatal conductance under fluctuating light in light of the trade-off between optimising CO 2 uptake and optimising water saving. This study suggests that stomatal dynamics under fluctuating light is closely related to drought resistance and hence detailed study is needed to enable its application in breeding drought tolerance in rice.

Purpose The contamination of agricultural soils by heavy metals is a worldwide problem. Organic amendments can be used for the immobilization and binding of heavy metal ions in soils by complexation, adsorption, and precipitation. A field trial was carried out to evaluate the influence of some low-cost organic materials such as rice straw (RS), green manure (GM), and pig manure (PM) on the distribution of Cu and Cd and the retention of these metals by organic matter fractions in heavy metal-polluted soils. Materials and methods The experiment was conducted in Miaoyunao Village, Daye County, Hubei province, China. PM, GM (peanut plants), and RS were obtained from a farm close to the village. Sixteen treatments with three replicates were designed. Soil chemical properties such as soil pH, electrical conductivity (EC), organic matter (OM), and available P were measured by standard methods. Soluble/ exchangeable, organic-bound, inorganic precipitates and residual Cu and Cd in the soil were sequentially extracted and analyzed. The amounts of Cu and Cd bound with soil particulate organic matter (POM) fractions and humic substances were also determined. Results and discussionThe addition of organic amendments declined significantly the concentrations of soluble/ exchangeable Cu and Cd, but increased the amounts of these metals in organic-bound and inorganic precipitate forms in the soil. RS was more effective than GM and PM in diminishing the solubility of Cu and Cd. The largest retention for Cu and Cd by humic substances and POM was noticed in RS treatments, whereas the lowest was found in PM treatments. Humic substances showed higher potential in the fixation of Cu and Cd than POM fractions. The conversion of soluble/exchangeable Cu and Cd to other insoluble forms after the application of organic amendments may be ascribed to the increases of soil OM, pH, EC, and available P contents. The highest binding of Cu and Cd with POM fractions and humic substances after the incorporation of RS mainly resulted from the greatest increase of soil OM contents. Conclusions RS, GM, and PM can be employed as good and cheap substances for the immobilization of Cu and Cd in heavy metal-polluted soils. RS was the best amendment in decreasing the solubility of Cu and Cd, and also in enhancing the retention of these metals by humic substances and POM fractions in the soil. Futures studies should focus on the influence of these organic amendments or their mixtures on the phytotoxicity of Cu and Cd for different plants in heavy metal-contaminated soils.