Soil diazotrophic abundance, diversity, and community assembly mechanisms significantly differ between glacier riparian wetlands and their adjacent alpine meadows

Global warming can trigger dramatic glacier area shrinkage and change the flux of glacial runoff, leading to the expansion and subsequent retreat of riparian wetlands. This elicits the interconversion of riparian wetlands and their adjacent ecosystems (e.g., alpine meadows), probably significantly impacting ecosystem nitrogen input by changing soil diazotrophic communities. However, the soil diazotrophic community differences between glacial riparian wetlands and their adjacent ecosystems remain largely unexplored. Here, soils were collected from riparian wetlands and their adjacent alpine meadows at six locations from glacier foreland to lake mouth along a typical Tibetan glacial river in the Namtso watershed. The abundance and diversity of soil diazotrophs were determined by real-time PCR and amplicon sequencing based on nifH gene. The soil diazotrophic community assembly mechanisms were analyzed via iCAMP, a recently developed null model-based method. The results showed that compared with the riparian wetlands, the abundance and diversity of the diazotrophs in the alpine meadow soils significantly decreased. The soil diazotrophic community profiles also significantly differed between the riparian wetlands and alpine meadows. For example, compared with the alpine meadows, the relative abundance of chemoheterotrophic and sulfate-respiration diazotrophs was significantly higher in the riparian wetland soils. In contrast, the diazotrophs related to ureolysis, photoautotrophy, and denitrification were significantly enriched in the alpine meadow soils. The iCAMP analysis showed that the assembly of soil diazotrophic community was mainly controlled by drift and dispersal limitation. Compared with the riparian wetlands, the assembly of the alpine meadow soil diazotrophic community was more affected by dispersal limitation and homogeneous selection. These findings suggest that the conversion of riparian wetlands and alpine meadows can significantly alter soil diazotrophic community and probably the ecosystem nitrogen input mechanisms, highlighting the enormous effects of climate change on alpine ecosystems

Comparison of thoracoabdominal versus abdominal-transhiatal surgical approaches in Siewert type II adenocarcinoma at the esophagogastric junction: Protocol for a prospective multicenter randomized controlled trial

BackgroundSiewert type II adenocarcinoma of the esophagogastric junction (Siewert II AEG) can be resected by the right thoracoabdominal surgical approach (RTA) or abdominal-transhiatal surgical approach (TH) under minimally invasive conditions. Although both surgical methods achieve complete tumor resection, there is a debate as to whether the former method is superior to or at least noninferior to the latter in terms of surgical safety. Currently, a small number of retrospective studies have compared the two surgical approaches, with inconclusive results. As such, a prospective multicenter randomized controlled trial is necessary to validate the value of RTA (Ivor-Lewis) compared to TH.MethodsThe planned study is a prospective, multicenter, randomized clinical trial. Patients (n=212) with Siewert II AEG that could be resected by either of the above two surgical approaches will be included in this trial and randomized to the RTA group (n=106) or the TH group (n=106). The primary outcome will be 3-year disease-free survival (DFS). The secondary outcomes will include 5-year overall survival (OS), incidence of postoperative complications, postoperative mortality, local recurrence rate, number and location of removed lymph nodes, quality of life (QOL), surgical Apgar score, and duration of the operation. Follow-ups are scheduled every three months for the first 3 years after the surgery and every six months for the next 2 years.DiscussionAmong Siewert II AEG patients with resectable tumors, this is the first prospective, randomized clinical trial comparing the surgical safety of minimally invasive RTA and TH. RTA is hypothesized to provide better digestive tract reconstruction and dissection of mediastinal lymph nodes while maintaining a high quality of life and good postoperative outcome. Moreover, this trial will provide a high level of evidence for the choice of surgical procedures for Siewert II AEG.Clinical trial registrationChinese Ethics Committee of Registering Clinical Trials, identifier (ChiECRCT20210635); Clinical Trial.gov, identifier (NCT05356520)

Evaluation of the blasting effects of insitu two-to-four lane expansion in the municipal tunnels based on EAHP model

To accurately evaluate the blasting effect of tunnel demolition, guarantee the normal traffic of vehicles during the blasting for insitu two-to-four lane expansion in the municipal tunnels, and reduce the risk of blasting demolition as well as expansion of existing tunnel linings, a comprehensive evaluation model of the tunnel blasting effect based on EAHP was established with the matter-element theory. First, 29 evaluation factors were selected from 5 aspects: blasting scheme design, surroundings of blasting area, blasting quality, blasting materials, blasting safety technology, and 5 evaluation grades were demarcated. Second, the primary correlation function established with extension transformation was adopted to calculate the correlation degree of influencing factors of blasting effects to the evaluation grade, an analytic hierarchy process (AHP) method was introduced to determine the index weight, and the blasting effect grade was determined according to the principle of maximum correlation degree. Therefore, an integrated evaluation method based on Extenics-AHP, namely, EAHP, was established. The results showed that this method was applied to the blasting effect evaluation of the insitu two-to-four lane expansion project in Loushan Tunnel in Zhejiang Province, and the blasting effect evaluation result was Kmax=K2=-0.030 9, namely, the blasting effect evaluation level of the insitu two-to-four lane expansion in the tunnel was "good blasting effect", which was consistent with the actual condition of the project. Therefore, the evaluation indexes and weight coefficients selected based on EAHP model were reasonable and reliable, and the maximum correlation degree obtained by extension transformation could also better reflect the grade of the tunnel blasting effect, indicating this evaluation method had better adaptability to tunnel blasting effect evaluation

Is there chiral correlation between graphitic layers in double-wall carbon nanotubes?

Because of the unique concentric structure, double-wall carbon nanotubes (DWNTs) possess fascinating properties which depend on the respective chirality of both the outer and the inner tubes. In this work, we study the chiral correlations of DWNTs synthesized by chemical vapor deposition on Fe nanoparticles. Contrary to some recent report, the distribution of chiral angle difference between inner and outer tubes in our work agrees with that calculated for all possible configurations. Remarkably, DWNTs with commensurate structures, i.e. outer and inner tubes have same chiral angles, are observed. The mechanism for the formation of DWNTs with approximately commensurate structures is discussed on the basis of layer by layer model. Furthermore, the interactional energies between the inner and outer walls are calculated to address the stability of different DWNT configurations. This work helps understand the growth mechanism of DWNTs and comprehend their structure stabilities with different configurations

A robust CoxMg1-xO catalyst for predominantly growing (6,5) single-walled carbon nanotubes

Chirality-controlled growth of single-walled carbon nanotubes (SWCNTs) by chemical vapor deposition (CVD) is one of the most challenging tasks in carbon nanotube synthesis field. During CVD growth, the catalyst plays crucial roles in governing SWCNT nucleation thermodynamics as well as growth kinetics. However, the performances of catalyst are generally sensitive to the metal loading amount in the catalyst and the reaction conditions, like the partial pressure of carbon source and the reaction time. In this work, we have systematically investigated a robust CoxMg1-xO solid solution, which can predominantly yield (6, 5) SWCNTs in a wide range of Co concentration, with a diversity of CO concentrations or a broad-ranging reaction time. Besides, the effect of reaction temperature on SWCNT chirality distribution is demonstrated, the mechanism of which is clarified with the assistance of environmental transmission electron microscopy. Finally, the chirality distribution of SWCNTs grown using CH4 as the carbon source is presented. The effects of carbon sources are discussed in view of SWCNT growth mode. (C) 2019 Elsevier Ltd. All rights reserved

Data_Sheet_1_Soil diazotrophic abundance, diversity, and community assembly mechanisms significantly differ between glacier riparian wetlands and their adjacent alpine meadows.PDF

Global warming can trigger dramatic glacier area shrinkage and change the flux of glacial runoff, leading to the expansion and subsequent retreat of riparian wetlands. This elicits the interconversion of riparian wetlands and their adjacent ecosystems (e.g., alpine meadows), probably significantly impacting ecosystem nitrogen input by changing soil diazotrophic communities. However, the soil diazotrophic community differences between glacial riparian wetlands and their adjacent ecosystems remain largely unexplored. Here, soils were collected from riparian wetlands and their adjacent alpine meadows at six locations from glacier foreland to lake mouth along a typical Tibetan glacial river in the Namtso watershed. The abundance and diversity of soil diazotrophs were determined by real-time PCR and amplicon sequencing based on nifH gene. The soil diazotrophic community assembly mechanisms were analyzed via iCAMP, a recently developed null model-based method. The results showed that compared with the riparian wetlands, the abundance and diversity of the diazotrophs in the alpine meadow soils significantly decreased. The soil diazotrophic community profiles also significantly differed between the riparian wetlands and alpine meadows. For example, compared with the alpine meadows, the relative abundance of chemoheterotrophic and sulfate-respiration diazotrophs was significantly higher in the riparian wetland soils. In contrast, the diazotrophs related to ureolysis, photoautotrophy, and denitrification were significantly enriched in the alpine meadow soils. The iCAMP analysis showed that the assembly of soil diazotrophic community was mainly controlled by drift and dispersal limitation. Compared with the riparian wetlands, the assembly of the alpine meadow soil diazotrophic community was more affected by dispersal limitation and homogeneous selection. These findings suggest that the conversion of riparian wetlands and alpine meadows can significantly alter soil diazotrophic community and probably the ecosystem nitrogen input mechanisms, highlighting the enormous effects of climate change on alpine ecosystems.</p