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1.
Castaldi  Simona  Smith  Keith A. 《Plant and Soil》1998,199(2):229-238
N2O emissions from two slightly alkaline sandy soils, from arable land and a woodland, were determined in a laboratory experiment in which the soils were incubated with different sources of nitrogen, with or without glucose, and with 0, 1 and 100 mL C2H2 L-1. Large differences in the rate of N2O production were observed between the two soils and between the different N treatments. The arable soil showed very low N2O emissions derived from reduced forms of N as compared with the N2O which was produced when the soil was provided with NO 2 - or NO 3 - and a C source, suggesting a very active denitrifier population. In contrast, the woodland soil showed a very low denitrification activity and a much higher N2O production derived from the oxidation of NH 4 + and reduction of NO 2 - by some processes probably mediated by autotrophic or heterotrophic nitrifiers or dissimilatory NO 2 - reducers. In both soils, the highest N2O emissions were induced by NO 2 - addition. Those emissions were demonstrated to have a biological origin, as no significant N2O emissions were measured when the soil was autoclaved.  相似文献   

2.
Butterbach-Bahl  K.  Willibald  G.  Papen  H. 《Plant and Soil》2002,240(1):105-116
In order to quantify N2-emissions from a spruce and a beech site at the Höglwald Forest, a new measuring system was developed, that allowed simultaneous, direct determination of N2- and N2O-emission with high accuracy (detection limit approx. 10 g N m–2 h–1 for N2 and <1 g for N2O) using a gas-flow core method. This method requires exchange of the soil atmosphere with an artificial atmosphere, that differs only in that N2 is substituted by He. The measuring system, the methodology of measurements and validation experiments are described in detail. Due to the huge heterogeneity of denitrification activity in different soil cores taken from our forest sites, no general trends of N2 and N2O production in relation to soil moisture and temperature could be demonstrated. Based on reasonable number of measurements, this work gives for the first time an estimate of the magnitude of N2-losses from temperate forest soils. Both the magnitude of N2-emissions (spruce: 7.2±0.7 kg N2-N ha–1 yr–1; beech: 12.4±3.1 kg N2-N ha–1 yr–1), as well as the N2O–N2 ratio (spruce: 0.136±0.04; beech: 0.52±0.19) were significantly higher for soils from the beech sites as compared to soils from the spruce site. The results suggests that N2-emissions from N-saturated forest soils, still receiving high loads of atmospheric N-deposition, are approx. 30% of atmospheric N-input at the spruce site, and approx. 50% at the beech site. Our results demonstrate that losses of nitrogen in the form of N2 cannot be neglected in the context of calculating N-balances for given forest sites.  相似文献   

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Second‐generation antipsychotics (SGAs) are recommended for maintenance treatment in schizophrenia. However, comparative long‐term effectiveness among SGAs is unclear. Here we provide a systematic review and meta‐analysis of randomized trials lasting ≥?6 months comparing SGAs head‐to‐head in schizophrenia and related disorders. The primary outcome was all‐cause discontinuation. Secondary outcomes included efficacy and tolerability, i.e., psychopathology, inefficacy‐related and intolerability‐related discontinuation, relapse, hospitalization, remission, functioning, quality of life, and adverse events. Pooled risk ratio and standardized mean difference were calculated using random‐effects models. Across 59 studies (N=45,787), lasting 47.4±32.1 weeks (range 24‐186), no consistent superiority of any SGA emerged across efficacy and tolerability outcomes. Regarding all‐cause discontinuation, clozapine, olanzapine and risperidone were significantly (p<0.05) superior to several other SGAs, while quetiapine was inferior to several other SGAs. As to psychopathology, clozapine and olanzapine were superior to several other SGAs, while quetiapine and ziprasidone were inferior to several other SGAs. Data for other efficacy outcomes were sparse. Regarding intolerability‐related discontinuation, risperidone was superior and clozapine was inferior to several other SGAs. Concerning weight gain, olanzapine was worse than all other compared non‐clozapine SGAs, and risperidone was significantly worse than several other SGAs. As to prolactin increase, risperidone and amisulpride were significantly worse than several other SGAs. Regarding parkinsonism, olanzapine was superior to risperidone, without significant differences pertaining to akathisia. Concerning sedation and somnolence, clozapine and quetiapine were significantly worse than some other SGAs. In summary, different long‐term SGA efficacy and tolerability patterns emerged. The long‐term risk‐benefit profiles of specific SGAs need to be tailored to individual patients to optimize maintenance treatment outcomes.  相似文献   

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Previous meta-analyses of psychotherapies for child and adolescent depression were limited because of the small number of trials with direct comparisons between two treatments. A network meta-analysis, a novel approach that integrates direct and indirect evidence from randomized controlled studies, was undertaken to investigate the comparative efficacy and acceptability of psychotherapies for depression in children and adolescents. Systematic searches resulted in 52 studies (total N=3805) of nine psychotherapies and four control conditions. We assessed the efficacy at post-treatment and at follow-up, as well as the acceptability (all-cause discontinuation) of psychotherapies and control conditions. At post-treatment, only interpersonal therapy (IPT) and cognitive-behavioral therapy (CBT) were significantly more effective than most control conditions (standardized mean differences, SMDs ranged from −0.47 to −0.96). Also, IPT and CBT were more beneficial than play therapy. Only psychodynamic therapy and play therapy were not significantly superior to waitlist. At follow-up, IPT and CBT were significantly more effective than most control conditions (SMDs ranged from −0.26 to −1.05), although only IPT retained this superiority at both short-term and long-term follow-up. In addition, IPT and CBT were more beneficial than problem-solving therapy. Waitlist was significantly inferior to other control conditions. With regard to acceptability, IPT and problem-solving therapy had significantly fewer all-cause discontinuations than cognitive therapy and CBT (ORs ranged from 0.06 to 0.33). These data suggest that IPT and CBT should be considered as the best available psychotherapies for depression in children and adolescents. However, several alternative psychotherapies are understudied in this age group. Waitlist may inflate the effect of psychotherapies, so that psychological placebo or treatment-as-usual may be preferable as a control condition in psychotherapy trials.  相似文献   

5.
Herein, this study successfully fabricates porous g‐C3N4‐based nanocomposites by decorating sheet‐like nanostructured MnOx and subsequently coupling Au‐modified nanocrystalline TiO2. It is clearly demonstrated that the as‐prepared amount‐optimized nanocomposite exhibits exceptional visible‐light photocatalytic activities for CO2 conversion to CH4 and for H2 evolution, respectively by ≈28‐time (140 µmol g?1 h?1) and ≈31‐time (313 µmol g?1 h?1) enhancement compared to the widely accepted outstanding g‐C3N4 prepared with urea as the raw material, along with the calculated quantum efficiencies of ≈4.92% and 2.78% at 420 nm wavelength. It is confirmed mainly based on the steady‐state surface photovoltage spectra, transient‐state surface photovoltage responses, fluorescence spectra related to the produced ?OH amount, and electrochemical reduction curves that the exceptional photoactivities are comprehensively attributed to the large surface area (85.5 m2 g?1) due to the porous structure, to the greatly enhanced charge separation and to the introduced catalytic functions to the carrier‐related redox reactions by decorating MnOx and coupling Au‐TiO2, respectively, to modulate holes and electrons. Moreover, it is suggested mainly based on the photocatalytic experiments of CO2 reduction with isotope 13CO2 and D2O that the produced ?CO2 and ?H as active radicals would be dominant to initiate the conversion of CO2 to CH4.  相似文献   

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Abstract Nilaparvata lugens (Stål) (Hemiptera: Geometroidea), a serious rice pest in many countries of Asia, causes a great loss in rice production every year. RNA interference (RNAi) is a powerful technology for gene function study in insects and a potential tool for pest control. As a core component of RNAi pathway, Dicer‐2 (Dcr‐2) protein determines the production of small interfering RNA (siRNA) and is crucial for the efficiency of RNAi. In this study, the full‐length complementary DNA (cDNA) of N. lugens Dcr‐2 (NlDcr‐2) was first cloned and analyzed, and then the RNAi experiment was conducted to explore the function of NlDcr‐2 gene. The complete Dcr‐2 cDNA of N. lugens was 4 971 bp in length with an open reading frame (ORF) of 1,656 amino acids. Phylogenetic and protein domain analysis showed that the predicted NlDcr‐2 protein was similar to Tribolium castaneum. In the RNAi experiment, the messenger RNA level of NlDcr‐2 was significantly reduced by NlDcr‐2 double‐stranded RNA (dsRNA) (dsDcr‐2). Fifty‐five per cent decrease of NlDcr‐2 was found after 4 days of unremitting feeding. No significant effect was observed on the development of N. lugens after dsRNA ingestion.  相似文献   

9.
The objective of this study was to evaluate the ability of one versatile peroxidase and the biocatalytically generated complex Mn(III)‐malonate to polymerize coniferyl alcohol (CA) to obtain dehydrogenation polymers (DHPs) and to characterize how closely the structures of the formed DHPs resemble native lignin. Hydrogen peroxide was used as oxidant and Mn2+ as mediator. Based on the yields of the polymerized product, it was concluded that the enzymatic reaction should be performed in aqueous solution without organic solvents at 4.5 ≤ pH ≤ 6.0 and with 0.75 ≤ H2O2:CA ratio ≤ 1. The results obtained from the Mn3+‐malonate‐mediated polymerization showed that the yield was almost 100%. Reaction conditions had, however, effect on the structures of the formed DHPs, as detected by size exclusion chromatography and pyrolysis‐GC/MS. It can be concluded that from the structural point of view, the optimal pH for DHP formation using the presently studied system was 3 or 4.5. Low H2O2/CA ratio was beneficial to avoid oxidative side reactions. However, the high frequency of β–β linkages in all cases points to dimer formation between monomeric CA rather than endwise polymerization. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:81–90, 2018  相似文献   

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Galactooligosaccharides (GOS) are prebiotics produced from lactose through an enzymatic reaction. Employing an immobilized enzyme may result in cost reductions; however, the changes in its kinetics due to immobilization has not been studied. This study experimentally determined the optimal reaction conditions for the production of GOS from lactose by β‐galactosidase (EC 3.2.1.23) from Kluyveromyces lactis covalently immobilized to a polysiloxane‐polyvinyl alcohol (POS‐PVA) polymer activated with glutaraldehyde (GA), and to study the transgalactosylation kinetics. Yield immobilization was 99 ± 1.1% with 78.5 ± 2.4% enzyme activity recovery. An experimental design 24 with 1 center point and 2 replicates was used. Factors were lactose [L], enzyme concentration [E], pH and temperature (T). Response variables were glucose and galactose as monosaccharides [G1], residual lactose [Lac]r and GOS as disaccharides [G2] and trisaccharides [G3]. Best conditions were pH 7.1, 40 °C, 270 gL?1 initial lactose concentration and 6 U mL?1 enzyme concentration, obtaining 25.46 ± 0.01 gL?1 yield of trisaccharides. Although below the HPLC‐IR detection limit, tetrasaccharides were also identified after 115 min of reaction. The immobilization protocol was then optimized by diminishing total reactant volumes : support ratio, resulting in improved enzyme activity synthesizing 43.53 ± 0.02 gL?1 of trisaccharides and 13.79 ± 0.21 gL?1 of tetrasaccharides, and after four cycles remaining relative activity was 94%. A reaction mechanism was proposed through which a mathematical model was developed and rate constants were estimated, considering a pseudo steady‐state hypothesis for two concomitant reactions, and from this simplified analysis, the reaction yield could eventually be improved. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1568–1578, 2017  相似文献   

13.
Comprehensive molecular profiling of human tumor tissue specimens at the DNA, mRNA and protein level is often obstructed by a limited amount of available material. Homogenization of frozen tissue samples in guanidine isothiocyanate followed by ultracentrifugation over cesium chloride allows the simultaneous extraction of high‐molecular weight DNA and RNA. Here, we present a protocol for quantitative proteome analysis using the high‐salt protein fraction obtained as supernatant after ultracentrifugation for nucleic acid extraction. We applied this method to extracts from primary human brain tumors and demonstrate its successful application for protein expression profiling in these tumors using 2‐D DIGE, MS and Western blotting.  相似文献   

14.
In this study are reported the syntheses of three bis(diarylhydrazonecarbonyl)methylene derivatives [{ArPhCNNH C(O)}2CH2] [Ar = 2 C5H4N (5), C6H5 (6), and 2‐C4H3S (7)], obtained by condensation of corresponding hydrazones with carbon suboxide, C3O2. The solid‐state self‐assembly of these carbonyl derivatives, giving rise to polymeric and dimeric networks, is described. In the formation of these structural features, in addition to N—H· · ·OC intermolecular hydrogen bonds, stabilizing intramolecular NH· · · π (systems) and intermolecular CO· · ·π (systems) interactions also seem to play an important role. Solution 1H‐nmr data of compounds 5–7 indicate that the polymeric and dimeric structures are not maintained in solution and show the occurrence of keto‐enolic equilibria. © 1999 John Wiley & Sons, Inc. Biopoly 49: 541–549, 1999  相似文献   

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