按提交时间
按主题分类
按作者
按机构
  • Host plant traits play a crucial role in shaping the composition of epiphytic microbiota in the arid desert, Northwest China

    分类: 生物学 >> 植物学 提交时间: 2024-05-15 合作期刊: 《干旱区科学》

    摘要: Phyllosphere microorganisms are a crucial component of environmental microorganisms, highly influenced by host characteristics, and play a significant role in plant health and productivity. Nonetheless, the impact of host characteristics on shaping phyllosphere microbial communities of plants with different life forms remains ambiguous. Utilizing high-throughput sequencing technology, this study analyzed the diversity and community composition of phyllosphere epiphytic microorganisms (e.g., bacteria and fungi) of various plant life forms in the hinterland of the Gurbantunggut Desert, Northwest China. Functional annotation of prokaryotic taxa (FAPROTAX) and fungi function guild (FUNGuild) were employed to assess the ecological functions of microorganisms and to investigate the role of stochastic and deterministic processes in shaping phyllosphere microbial communities. Result showed a diverse array of phyllosphere epiphytic microorganisms in the desert plants, with Proteobacteria, Cyanobacteria, and Actinobacteriota dominating bacterial community, while Ascomycota and Basidiomycota were prevalent in fungal community. Comparison across different plant life forms highlighted distinct microbial communities, indicating strong filtering effects by plant characteristics. FAPROTAX prediction identified intracellular parasites (accounting for 27.44% of bacterial community abundance), chemoheterotrophy (10.12%), and phototrophy (17.41%) as the main functions of epiphytic bacteria on leaves of different life form plants. FUNGuild prediction indicated that phyllosphere epiphytic fungi primarily served as Saprotrophs (81.77%), Pathotrophs (17.41%), and Symbiotrophs (0.82%). Co-occurrence network analysis demonstrated a predominance of positive correlations among different microbial taxa. Raup-Crick dissimilarity index analysis revealed that deterministic processes predominantly influenced phyllosphere bacterial and fungal community assembly. Variance partitioning analysis and random forest modeling suggested that plant leaf functional traits significantly impacted both bacterial and fungal community composition, with fungal community composition showing a closer association with leaf nutrients and physiology compared with bacterial community composition. The distinct responses of bacterial and fungal communities to plant traits were attributed to the differing properties of bacteria and fungi, such as bacteria having higher potential dispersal rates and broader ecological niches than fungi. Overall, the results indicate that phyllosphere bacterial and fungal communities undergo similar community assembly processes, with fungi being more influenced by plant characteristics than bacteria. These findings offer novel insights into the ecology of phyllosphere microbial communities of desert plants.

  • Low soil temperature reducing the yield of drip irrigated rice in arid area by influencing anther development and pollination

    分类: 生物学 >> 植物学 提交时间: 2019-06-20 合作期刊: 《干旱区科学》

    摘要: Drip irrigation can produce high rice yields with significant water savings; therefore, it is widely used in arid area water-scarce northern China. However, high-frequency irrigation of drip irrigation with low temperature well water leads to low root zone temperature and significantly reduce the rice yield compared to normal temperature water irrigated rice, for example, reservoir water. The main purpose of this paper is to investigate the effects of low soil temperature on the yield reduction of drip irrigated rice in the spike differentiation stage. The experiment set the soil temperatures at 18°C, 24°C and 30°C under two irrigation methods (flood and drip irrigation), respectively. The results showed that, at the 30°C soil temperature, drip irrigation increased total root length by 53% but reduced root water conductivity by 9% compared with flood irrigation. Drip irrigation also increased leaf abscisic acid and proline concentrations by 13% and 5%, respectively. These results indicated that drip irrigated rice was under mild water stress. In the 18°C soil temperature, drip irrigation reduced hydraulic conductivity by 58%, leaf water potential by 40% and leaf net photosynthesis by 25% compared with flood irrigation. The starch concentration in male gametes was also 30% less in the drip irrigation treatment than in the flood irrigation treatment at soil temperature 18°C. Therefore, the main reason for the yield reduction of drip irrigated rice was that the low temperature aggravates the physiological drought of rice and leads to the decrease of starch content in male gametes and low pollination fertilization rate. Low temperature aggravates physiological water deficit in drip irrigated rice and leads to lower starch content in male gametes and low pollination fertilization rate, which is the main reason for the reduced yield of drip irrigated rice. Overall, the results indicated that the low soil temperatures aggravated the water stress that rice was under in the drip irrigated environment, causing declines both in the starch content of male gametes and in pollination rate. Low temperature will ultimately affect the rice yield under drip irrigation.

  • The control and measurement of high power high-gradient acceleration structures

    分类: 核科学技术 >> 粒子加速器 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》

    摘要: Conditioning an accelerating structure is important, and its performance is limited by breakdown and vacuum degradation, hence the necessity of finding problem in the conditioning. In order to save time, a judging process built in the firmware layer is applied in this paper. The system using the embedded algorithm in the Field Programmable Gate Array (FPGA) locates the position of breakdown and displays the result in the user interface. Also, the system has the functions of automatic conditioning and interlock protection, which are useful during the conditioning process of an S-band accelerating structure.

  • Quantification of groundwater recharge and evapotranspiration along a semi-arid wetland transect using diurnal water table fluctuations

    分类: 地球科学 >> 地理学 提交时间: 2021-06-04 合作期刊: 《干旱区科学》

    摘要: Groundwater is a vital water resource in arid and semi-arid areas. Diurnal groundwater table fluctuations are widely used to quantify rainfall recharge and groundwater evapotranspiration (ETg). To assess groundwater resources for sustainable use, we estimated groundwater recharge and ETg using the diurnal water table fluctuations at three sites along a section with different depths to water table (DWT) within a wetland of the Mukai Lake in the Ordos Plateau, Northwest China. The water table level was monitored at an hourly resolution using a Keller DCX-22A data logger that measured both the total pressure and barometric pressure, so that the effect of barometric pressure could be removed. At this study site, a rapid water table response to rainfall was observed in two shallow wells (i.e., Obs1 and Obs2), at which diurnal water table fluctuations were also observed over the study period during rainless days, indicating that the main factors influencing water table variation are rainfall and ETg. However, at the deep-water table site (Obs3), the groundwater level only reacted to the heaviest rainfalls and showed no diurnal variations. Groundwater recharge and ETg were quantified for the entire hydrological year (June 2017–June 2018) using the water table fluctuation method and the Loheide method, respectively, with depth-dependent specific yields. The results show that the total annual groundwater recharge was approximately 207 mm, accounting for 52% of rainfall at Obs1, while groundwater recharge was approximately 250 and 21 mm at Obs2 and Obs3, accounting for 63% and 5% of rainfall, respectively. In addition, the rates of groundwater recharge were mainly determined by rainfall intensity and DWT. The daily mean ETg at Obs1 and Obs2 over the study period was 4.3 and 2.5 mm, respectively, and the main determining factors were DWT and net radiation.

  • Effects of climate change and land-use changes on spatiotemporal distributions of blue water and green water in Ningxia, Northwest China

    分类: 地球科学 >> 地理学 提交时间: 2021-08-06 合作期刊: 《干旱区科学》

    摘要: Water resources are a crucial factor that determines the health of ecosystems and socio-economic development; however, they are under threat due to climate change and human activities. The quantitative assessment of water resources using the concept of blue water and green water can improve regional water resources management. In this study, spatiotemporal distributions of blue water and green water were simulated and analyzed under scenarios of climate change and land-use changes using the Soil and Water Assessment Tool (SWAT) in Ningxia Hui Autonomous Region, Northwest China, between 2009 and 2014. Green water, a leading component of water resources, accounted for more than 69.00% of the total water resources in Ningxia. Blue water and green water showed a single peak trend on the monthly and annual scales during the study period. On the spatial scale, the southern region of Ningxia showed higher blue water and green water resources than the northern region. The spatiotemporal distribution features of blue water, green water, and green water flow had strong correlations with precipitation. Furthermore, the simulation identified the climate change in Ningxia to be more influential on blue water and green water than land-use changes. This study provides a specific scientific foundation to manage water resources in Ningxia when encountered with climate change together with human activities.

  • 用于小麦多生长阶段倒伏边界精准检测的分层交互特征金字塔网络

    分类: 农、林、牧、渔 >> 农、林、牧、渔业科学其他学科 提交时间: 2024-06-17 合作期刊: 《智慧农业(中英文)》

    摘要: [目的/意义]传统的小麦倒伏检测方法需要人工进行田间观测和记录,这种方法存在主观、效率低、劳 动强度大等问题,难以满足大规模的小麦倒伏检测的需求。基于深度学习的小麦倒伏检测技术虽已在一定程度上 得到应用,但普遍局限于对小麦单一发育阶段的倒伏识别,而倒伏可能发生在小麦生长的各个时期,不同时期倒 伏特征变化复杂,这给模型特征捕捉能力带来考验。本研究旨在探索一种基于深度学习技术的多生育期小麦倒伏 区域检测方法。[方法]用无人机采集小麦灌浆期、早熟期、晚熟期这三个关键生长阶段的RGB图像,通过数据 增强等技术构建出多生育期小麦倒伏数据集。提出一种小麦倒伏提取模型Lodging2Former,该模型在Mask2Former 的基础上加以改进,引入分层交互式特征金字塔网络(Hierarchical Interactive Feature Pyramid Network, HI-FPN ), 用于提高模型在复杂田间背景干扰下对于多个生长阶段小麦倒伏特征的捕捉能力。[结果和讨论]所提出的Lodg⁃ ing2Former模型相较于现存的多种主流算法,如Mask R-CNN (Mask Region-Based Convolutional Neural Network)、 SOLOv2(Segmenting Objects by Locations, Version 2) 以及Mask2Former,在平均精度均值(mean Average Precision, mAP) 上展现出显著优势。在阈值分别为0.5、0.75以及0.5~0.95的条件下,模型的mAP值分别达到了79.5%、 40.2%和43.4%,相比Mask2Former模型,mAP性能提升了1.3%~4.3%。[结论]提出的HI-FPN网络可以有效利用 图像中的上下文语义和细节信息,通过提取丰富的多尺度特征,增强了模型对小麦在不同生长阶段倒伏区域的检 测能力,证实了HI-FPN在多生育期小麦倒伏检测中的应用潜力和价值。

  • DRC-Net Method for Two-dimensional Spectral Classification

    分类: 物理学 >> 地球物理学、天文学和天体物理学 提交时间: 2024-01-09 合作期刊: 《Research in Astronomy and Astrophysics》

    摘要: Spectral classification plays a crucial role in the analysis of astronomical data. Currently, stellar spectral classification primarily relies on one-dimensional (1D) spectra and necessitates a sufficient signal-to-noise ratio (S/N). However, in cases where the S/N is low, obtaining valuable information becomes impractical. In this paper, we propose a novel model called DRC-Net (Double-branch celestial spectral classification network based on residual mechanisms) for stellar classification, which operates solely on two-dimensional (2D) spectra. The model consists of two branches that use 1D convolutions to reduce the dimensionality of the 2D spectral composed of both blue and red arms. In the following, the features extracted from both branches are fused, and the fused result undergoes further feature extraction before being fed into the classifier for final output generation. The data set is from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, comprising 15,680 spectra of F, G, and K types. The preprocessing process includes normalization and the early stopping mechanism. The experimental results demonstrate that the proposed DRC-Net achieved remarkable classification precision of 93.0%, 83.5%, and 86.9% for F, G, and K types, respectively, surpassing the performance of 1D spectral classification methods. Furthermore, different S/N intervals are tested to judge the classification ability of DRC-Net. The results reveal that DRC-Net, as a 2D spectral classification model, can deliver superior classification outcomes for the spectra with low S/Ns. These experimental findings not only validate the efficiency of DRC-Net but also confirm the enhanced noise resistance ability exhibited by 2D spectra.

  • cDNA microarray analysis of differential gene expression and regulation in clinically drug-resistant isolates of Candida albicans from bone marrow transplanted patients

    分类: 生物学 >> 生物医药 提交时间: 2017-03-30

    摘要: Fungi have emerged as the fourth most common pathogens isolated in nosocomial bloodstream infections, and Candida albicans is the most common human fungal pathogen. Only a few antibiotics are effective in the treatment of fungal infections. In addition, the repetition and lengthy duration of fluconazole therapy has led to an increased incidence of azole resistance and treatment failure associated with C. albicans. To investigate the mechanism of drug resistance and explore new targets to treat clinically resistant fungal pathogens, we examined the large-scale gene expression profile of two sets of matched fluconazole-susceptible and -resistant bloodstream C. albicans isolates from bone marrow transplanted (BMT) patients for the first time by microarray analysis. More than 198 differentially expressed genes were identified and they were confirmed and validated by RT-PCR independently. Not surprisingly, the resistant phenotype is associated with increased expression of CDR mRNA, as well as some common genes involved in drug resistance such as CaIFU5, CaRTA2 and CaIFD6. Meanwhile, some special functional groups of genes, including ATP binding cassette (ABC) transporter genes (IPF7530, CaYOR1, CaPXA1), oxidative stress response genes (CaALD5, CaGRP1, CaSOD2, IPF10565), copper transport and iron mobilization-related genes (CaCRD1/2, CaCTR1/2, CaCCC2, CaFET3) were found to be differentially expressed in the resistant isolates. Furthermore, among these differentially expressed genes, some co-regulated with CaCDR1, CaCDR2 and CaIFU5, such as CaPDR16 and CaIFD6, have a DRE-like element and may interact with TAC1 in the promoter region. These findings may shed light on mechanisms of azole resistance in C. albicans and clinical antifungal therapy.

  • Synthesis of poly[butylene terephthalate]-poly[tetramethylene glycol] copolymers using terephthalic acid as starting material: A comparation between two synthetic strategies

    提交时间: 2017-05-02

    摘要: Poly[butylene terephthalate]-poly[tetramethylene glycol] [PBT-PTMG] copolymer is prepared with terephthalic acid [PTA] rather than its dimethyl ester [DMT] as starting material by a two-step melt polycondensation. This process includes the synthesis of PB