First Total Synthesis of a Naturally Occurring Iodinated 5′-Deoxyxylofuranosyl Marine Nucleoside

4-Amino-7-(5′-deoxy-β-D-xylofuranosyl)-5-iodo-pyrrolo[2,3-d]pyrimidine 1, an unusual naturally occurring marine nucleoside isolated from an ascidan, Diplosoma sp., was synthesized from D-xylose in seven steps with 28% overall yield on 10 g scale. The key step was Vorbrüggen glycosylation of 5-iodo-pyrrolo[2,3-d]pyrimidine with 5-deoxy-1,2-O-diacetyl-3-O-benzoyl-D-xylofuranose. Its absolute configuration was confirmed

Study on multi-period palaeotectonic stress fields simulation and fractures distribution prediction in Lannigou gold mine, Guizhou

A significant controlling factor for gold mineralisation is the tectonic stress field, and the fractures formed under its action are the migration channels and ore-holding spaces of ore-forming fluids, which often directly control the migration and accumulation of ore-forming fluids. Therefore, performing quantitative prediction research on the distribution of fractures in the Guizhou, Lannigou gold deposit in order to identify potential fluid flow pathways is of utmost importance for ore prospecting in practical. In this study, a 3D geological entity model was generated based on the GOCAD platform by analysing and processing the geological data of the studied area, as well achieved is the accurate characterisation of the study area’s geometric model. By integrating regional tectonic evolution history analysis, geological interpretation, rock mechanics experiments and acoustic emission testing, the finite element method was utilised to create a 3D geomechanical model of the research area, the paleotectonic stress field after the Indosinian and Yanshanian movements were superimposed was simulated, in associated with the rock failure criterion, the comprehensive fracture rate parameter (Iz) is introduced to predict the fracture distribution. The results show that the research area’s maximum principal stress is primarily distributed between 153.85 and 189.53 MPa, and the maximum shear stress is between 83.53 and 98.42 MPa. The spatial distribution of faults influences the stress distribution characteristics significantly, and the stress level is relatively high at the intersection of the fault, the end of the fault and the vicinity of the fault zone, and the stress value between the faults is relatively low. The tectonic stress field primarily controls the distribution and development of fractures, which is usually consistent with the areas with high values of maximum principal stress and maximum shear stress. Using the combined modeling technique of GOCAD and midas GTS to realize the conversion from 3D geological model to geomechanical model, a set of comprehensive fracture distribution prediction technique for the superposition of multi-stage tectonic stress fields of mineral deposits in complex tectonic areas has been formed, and provide a reference for the prediction of fracture distribution in similar complex structural areas.This study was supported by the program of China Scholarships Council (No. 202006670005); the National Natural Science Foundation of China (Project Nos. 51964007, 52264004, 52104080, 41962008); the Guizhou Province Science and Technology Support Program Project (Number: QIANKEHE Support [2021] General 516); Scientific and Technological Innovation Talents Team in Guizhou Province (Project No. [2019]5619); the Guizhou Province Highlevel Innovative Talents Training Project (Grant No. JZ2016-4011). Major Collaborative Innovation Project for Strategic Action of Mineral Search Breakthrough in Guizhou Province ([2022] ZD005); Natural Science Special (Special Post) Scientific Research Fund Project of Guizhou University (Project No. Guizhou University Special Post (2021) 51).Peer ReviewedPostprint (published version

INT: Towards Infinite-frames 3D Detection with An Efficient Framework

It is natural to construct a multi-frame instead of a single-frame 3D detector for a continuous-time stream. Although increasing the number of frames might improve performance, previous multi-frame studies only used very limited frames to build their systems due to the dramatically increased computational and memory cost. To address these issues, we propose a novel on-stream training and prediction framework that, in theory, can employ an infinite number of frames while keeping the same amount of computation as a single-frame detector. This infinite framework (INT), which can be used with most existing detectors, is utilized, for example, on the popular CenterPoint, with significant latency reductions and performance improvements. We've also conducted extensive experiments on two large-scale datasets, nuScenes and Waymo Open Dataset, to demonstrate the scheme's effectiveness and efficiency. By employing INT on CenterPoint, we can get around 7% (Waymo) and 15% (nuScenes) performance boost with only 2~4ms latency overhead, and currently SOTA on the Waymo 3D Detection leaderboard.Comment: accepted by ECCV202

Determination of 6 kinds of carbamate pesticides and 3 kinds of chloronicotinyl pesticides in Chinese Kushui rose by ultra high performance liquid chromatography-tandem mass spectrometry coupled with QuEChERS

Objective To establish a method for determination of 6 kinds of carbamate pesticides and 3 kinds of chloronicotinyl pesticides in Chinese Kushui rose by ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) coupled with QuEChERS. Methods After extracted by acetonitrile, the Chinese Kushui rose was cleaned by QuEChERS. The target compounds were separated by C18 column (2.1 mm×100 mm, 1.7 μm) using 10 mmol/L ammonium acetate solution (0.1% formic acid) with acetonrtrile as mobile phase for gradient elution, and analyzed by MS/MS system with electrospray ionization (ESI+) under muti-reaction monitoring mode and quantified by external standard method. Results All the 9 kinds of pesticides showed good linear relationships in range of 0.01-0.50 μg/mL, and the correlation coefficients were above 0.990, the recoveries at different spiked levels for all target compounds in blank matrices were 76.3%-102%, and the relative standard deviation (RSD) were 1.3%-9.0% (n=6). The limits of detection and quantification of the method were 0.001 6-0.003 2 and 0.005 4-0.010 mg/kg. Conclusion The method was suitable for rapid screening and analysis of 9 pesticide residues in Chinese Kushui rose with the advantage of accuracy, rapidity, simplicity and high sensitivity

Evaluation of the IP-10 mRNA release assay for diagnosis of TB in HIV-infected individuals

HIV-infected individuals are susceptible to Mycobacterium tuberculosis (M.tb) infection and are at high risk of developing active tuberculosis (TB). Interferon-gamma release assays (IGRAs) are auxiliary tools in the diagnosis of TB. However, the performance of IGRAs in HIV-infected individuals is suboptimal, which limits clinical application. Interferon-inducible protein 10 (IP-10) is an alternative biomarker for identifying M.tb infection due to its high expression after stimulation with M.tb antigens. However, whether IP-10 mRNA constitutes a target for the diagnosis of TB in HIV-infected individuals is unknown. Thus, we prospectively enrolled HIV-infected patients with suspected active TB from five hospitals between May 2021 and May 2022, and performed the IGRA test (QFT-GIT) alongside the IP-10 mRNA release assay on peripheral blood. Of the 216 participants, 152 TB patients and 48 non-TB patients with a conclusive diagnosis were included in the final analysis. The number of indeterminate results of IP-10 mRNA release assay (13/200, 6.5%) was significantly lower than that of the QFT-GIT test (42/200, 21.0%) (P = 0.000026). IP-10 mRNA release assay had a sensitivity of 65.3% (95%CI 55.9% – 73.8%) and a specificity of 74.2% (95%CI 55.4% – 88.1%), respectively; while the QFT-GIT test had a sensitivity of 43.2% (95%CI 34.1% – 52.7%) and a specificity of 87.1% (95%CI 70.2% – 96.4%), respectively. The sensitivity of the IP-10 mRNA release assay was significantly higher than that of QFT-GIT test (P = 0.00062), while no significant difference was detected between the specificities of these two tests (P = 0.198). The IP-10 mRNA release assay showed a lower dependence on CD4+ T cells than that of QFT-GIT test. This was evidenced by the fact that the QFT-GIT test had a higher number of indeterminate results and a lower sensitivity when the CD4+ T cells counts were decreased (P < 0.05), while no significant difference in the number of indeterminate results and sensitivity were observed for the IP-10 mRNA release assay among HIV-infected individuals with varied CD4+T cells counts (P > 0.05). Therefore, our study suggested that M.tb specific IP-10 mRNA is a better biomarker for diagnosis of TB in HIV-infected individuals

Global sensitivity analysis in hydrological modeling: Review of concepts, methods, theoretical framework, and applications

Sensitivity analysis (SA) aims to identify the key parameters that affect model performance and it plays important roles in model parameterization, calibration, optimization, and uncertainty quantification. However, the increasing complexity of hydrological models means that a large number of parameters need to be estimated. To better understand how these complex models work, efficient SA methods should be applied before the application of hydrological modeling. This study provides a comprehensive review of global SA methods in the field of hydrological modeling. The common definitions of SA and the typical categories of SA methods are described. A wide variety of global SA methods have been introduced to provide a more efficient evaluation framework for hydrological modeling. We review, analyze, and categorize research into global SA methods and their applications, with an emphasis on the research accomplished in the hydrological modeling field. The advantages and disadvantages are also discussed and summarized. An application framework and the typical practical steps involved in SA for hydrological modeling are outlined. Further discussions cover several important and often overlooked topics, including the relationship between parameter identification, uncertainty analysis, and optimization in hydrological modeling, how to deal with correlated parameters, and time-varying SA. Finally, some conclusions and guidance recommendations on SA in hydrological modeling are provided, as well as a list of important future research directions that may facilitate more robust analyses when assessing hydrological modeling performance

Exploring the Effects of Urban Built Environment on Road Travel Speed Variability with a Spatial Panel Data Model

Road traffic congestion is a common problem in most large cities, and exploring the root causes is essential to alleviate traffic congestion. Travel behavior is closely related to the built environment, and affects road travel speed. This paper investigated the direct effect of built environment on the average travel speed of road traffic. Taxi trajectories were divided into 30 min time slot (48 time slots throughout the day) and matched to the road network to obtain the average travel speed of road segments. The Points of Interest (POIs) in the buffer zone on both sides of the road segment were used to calculate the built environment indicators corresponding to the road segment, and then a spatial panel data model was proposed to assess the influence of the built environment adjacent to the road segment on the average travel speed of the road segment. The results demonstrated that the bus stop density, healthcare service density, sports and leisure service density, and parking entrance and exit density are the key factors that positively affect the average road travel speed. The residential community density and business building density are the key factors that negatively affect the average travel speed. Built environments have spatial correlation and spatial heterogeneity in their influence on the average travel speed of road segments. Findings of this study may provide useful insights for understanding the correlation between road travel speed and built environment, which would have important implications for urban planning and governance, traffic demand forecasting and traffic system optimization

Exploring the Effects of Urban Built Environment on Road Travel Speed Variability with a Spatial Panel Data Model

Road traffic congestion is a common problem in most large cities, and exploring the root causes is essential to alleviate traffic congestion. Travel behavior is closely related to the built environment, and affects road travel speed. This paper investigated the direct effect of built environment on the average travel speed of road traffic. Taxi trajectories were divided into 30 min time slot (48 time slots throughout the day) and matched to the road network to obtain the average travel speed of road segments. The Points of Interest (POIs) in the buffer zone on both sides of the road segment were used to calculate the built environment indicators corresponding to the road segment, and then a spatial panel data model was proposed to assess the influence of the built environment adjacent to the road segment on the average travel speed of the road segment. The results demonstrated that the bus stop density, healthcare service density, sports and leisure service density, and parking entrance and exit density are the key factors that positively affect the average road travel speed. The residential community density and business building density are the key factors that negatively affect the average travel speed. Built environments have spatial correlation and spatial heterogeneity in their influence on the average travel speed of road segments. Findings of this study may provide useful insights for understanding the correlation between road travel speed and built environment, which would have important implications for urban planning and governance, traffic demand forecasting and traffic system optimization

Relative Voltage Control of the Wind Farms Based on the Local Reactive Power Regulation

The fast and coordinated voltage control of distributed nodes inside a large scale wind farm is a stringent issue. To achieve the reactive power compensation without a dedicated upper communication system, this paper proposes a relative control strategy based on the local reactive power regulation. This method can realize the voltage coordination of the key equipment and feeder line nodes, on the basis of the relative voltage observations. Firstly, the stability analysis of a certain wind farm with pre-known parameters and structure is studied under the wind power fluctuations. Secondly, the optimal capacity configurations of the reactive power compensators are discussed, with multiple nodes inside the wind farms. Simulation results of a specific wind farm in North Hebei, China, validate the effectiveness of the proposed control, which is equipped with fast and stable voltage dynamic responses, as well as local reactive power compensations without remote communication