Transition-Metal-Free Approach to Acridone Derivatives by TBHP-Promoted Oxidative Annulation of Isatins with Arynes.

A -butyl hydroperoxide-promoted oxidative annulation reaction of isatins with 2-(trimethylsilyl)aryl triflates for the convenient synthesis of acridone derivatives has been established. Mechanistic investigation suggested that the reaction may proceed via consecutive Baeyer-Villiger-type rearrangement followed by an intermolecular cyclization. This synthetic approach offers several advantages, including broad substrate scope, good functional group tolerance, and simplicity of operation.

Hydrothermal Reduction of CO to Value-Added Products by In Situ Generated Metal Hydrides.

An integrated process by coupling hydrothermal reactions, including CO reduction and HO dissociation with metals, is proposed. The hydrogen could be rapidly produced under hydrothermal conditions, owing to the special characteristics of high temperature water, generating metal hydrides as intermediates. Hydrogen production from the HO dissociation under hydrothermal conditions is one of the most ideal processes due to its environmentally friendly impact.

Artificial intelligence reveals dysregulation of osteosarcoma and cuproptosis-related biomarkers, PDHA1, CDKN2A and neutrophils.

At present, the impact of cuproptosis-related genes in the study of osteosarcoma is largely unknown. Genome-wide data of osteosarcoma and controls were downloaded from 3 different databases, and specific diagnostic models associated with cuproptosis in osteosarcoma were constructed by support vector machines with artificial intelligence, random forest trees and LASSO regression. Differential analysis of immune cell infiltration was examined using routine blood data from 25,665 cases.

[Temporal and Spatial Characteristics of Net CO Emissions and Decoupling Analysis in Yangtze River Economic Belt].

Calculating the fossil energy consumption, revealing the temporal and spatial evolution characteristics of net CO emissions, and analyzing the decoupling effect between social development and net CO emissions in different regions of the Yangtze River Economic Belt (YREB) is crucial to support the different regions, allowing them to select their individual industrial development and carbon emission reduction path. The results showed that:① from 1999 to 2012, YREB became greener, the CO emission of the YREB increased by 2244.23 million tons, and the carbon sink increased by 148.

Joint Estimation of Mass and Center of Gravity Position for Distributed Drive Electric Vehicles Using Dual Robust Embedded Cubature Kalman Filter.

The accurate estimation of the mass and center of gravity (CG) position is key to vehicle dynamics modeling. The perturbation of key parameters in vehicle dynamics models can result in a reduction of accurate vehicle control and may even cause serious traffic accidents. A dual robust embedded cubature Kalman filter (RECKF) algorithm, which takes into account unknown measurement noise, is proposed for the joint estimation of mass and CG position.

New Insight into CO Reduction to Formate by In Situ Hydrogen Produced from Hydrothermal Reactions with Iron.

To reveal the nature of CO reduction to formate with high efficiency by in situ hydrogen produced from hydrothermal reactions with iron, DFT calculations were used. A reaction pathway was proposed in which the formate was produced through the key intermediate species, namely iron hydride, produced in situ in the process of hydrogen gas production. In the in situ hydrogenation of CO, the charge of H in the iron hydride was -0.

Rh(III)-Catalyzed Tandem Reaction Access to (Quinazolin-2-yl)methanone Derivatives from 2,1-Benzisoxazoles and α-Azido Ketones.

A Rh(III)-catalyzed tandem reaction for the synthesis of (quinazolin-2-yl)methanone derivatives has been explored from 2,1-benzisoxazoles and α-azido ketones. The transformation involves Rh(III)-catalyzed denitrogenation of α-azido ketones, aza-[4 + 2] cycloaddition, ring opening, and dehydration aromatization processes. Notably, the aza-[4 + 2] cycloaddition of an imine rhodium complex intermediate with 2,1-benzisoxazoles is the key to this reaction.

Potential application of carbohydrate biomass in hydrometallurgy: one-pot reduction of metal oxides/salts under mild hydrothermal conditions.

Carbohydrate biomass can be employed as a reductant for metallic material preparation due to it possessing diverse reducing functional groups. The reported studies focused on reduction of metal ions in acidic solution with the aid of biomass. However, we found alkali hydrothermal conditions are favorable to metal compound reduction, even direct conversion of metal oxides to metals.

Analysis of stiffness and damping performance of the composite leaf spring.

Lightweight design of leaf springs is conducive to reducing fuel consumption and improving vehicle comfort. The weight of leaf spring can be reduced obviously by using composite material. Stiffness and damping are the key factors that affect the properties of the leaf spring.

A robust H∞-based steering assistance system for the wheeled tractor.

Agricultural machine automatic navigation poses great challenge to the precise agricultural technology system nowadays. To this end, this paper proposes a novel steering assistance system (SAS) to assist drivers in the path-tracking. First, the driver steering model is investigated through the driver simulator tests.

Multi-scale assessment of water security under climate change in North China in the past two decades.

Climate change is projected to affect the hydrological cycles in China, while the effects are expected to vary spatiotemporally. Understanding the variations in water security conditions and their sensitivity to climatic variables is crucial for assessing regional ecosystem responses to climate change. In the present study, we estimated the water yield capacity, an important indicator of water security in North China (NC), at a spatial resolution of 1 km during the last two decades based on the Budyko framework and quantified the sensitivity of water yield change to climate change among different vegetation types.

Therapeutic effects of full endoscopic spine surgery via transforaminal approach in elderly patients with lumbar spinal stenosis: A retrospective clinical study.

Objective: This study aimed to investigate the therapeutic effects of full endoscopic spine surgery on clinical and radiological outcomes in elderly patients over 70 years with lumbar spinal stenosis, without any obvious segmental instability.

Methods: A total of 47 patients (27 males, 20 females; the mean age=74.23±5.

Robust Inter-Vehicle Distance Measurement Using Cooperative Vehicle Localization.

Precise localization is critical to safety for connected and automated vehicles (CAV). The global navigation satellite system is the most common vehicle positioning method and has been widely studied to improve localization accuracy. In addition to single-vehicle localization, some recently developed CAV applications require accurate measurement of the inter-vehicle distance (IVD).

Comparative Analysis of the Therapeutic Efficiency and Radiographic Measurement Between the Transforaminal Approach and Interlaminar Approach in Percutaneous Endoscopic Discectomy.

Aim: To investigate and compare the therapeutic efficiency and radiographic measurement between the transforaminal approach and interlaminar approach in percutaneous endoscopic discectomy.

Material And Methods: From January 2017 to January 2018, 86 patients suffering from single lumbar disc herniation were included in this retrospective analysis and divided into the percutaneous endoscopic transforaminal discectomy (PETD) group and percutaneous endoscopic interlaminar discectomy (PEID) group according to different surgical approaches. Data on age, gender, course of the disease, smoking status, and body mass index (BMI) were also obtained.

Merging Annulation with Ring Deconstruction: Synthesis of ()-3-(2-Acyl-1-benzo[]imidazol-4-yl)acrylaldehyde Derivatives via I/FeCl-Promoted Dual C(sp)-H Amination/C-N Bond Cleavage.

An unprecedented I/FeCl-promoted cascade reaction of aryl methyl ketones with 8-aminoquinolines for the convenient synthesis of ()-3-(2-acyl-1-benzo[]imidazol-4-yl)acrylaldehydes was developed by merging annulation with ring deconstruction. This novel strategy unlocked the new reactivity of 8-aminoquinolines and provided an attractive platform for the ring opening of unactivated -heteroaromatic compounds. Preliminary mechanistic investigation suggested that dual C(sp)-H amination/C-N bond cleavage were key reaction steps.

Iodine-Promoted Multicomponent Synthesis of 2,4-Diamino-1,3,5-triazines.

A novel and efficient multicomponent cyclization of methyl ketones, cyanamides, and arylamines for the synthesizing 2,4-diamino-1,3,5-triazines via consecutive formation of four C-N bonds is reported. This multicomponent reaction is characterized by the employment of two molecules of cyanamide for double C(sp)-H amination of methyl ketones, avoiding complicated prepreparation of substrates and expanding the substrate scope. Furthermore, this multicomponent cyclization strategy provides a new approach for generating diverse 2,4-diamino-1,3,5-triazines with a broad substrate scope under mild conditions.

Scaling Effects on Chlorophyll Content Estimations with RGB Camera Mounted on a UAV Platform Using Machine-Learning Methods.

Timely monitoring and precise estimation of the leaf chlorophyll contents of maize are crucial for agricultural practices. The scale effects are very important as the calculated vegetation index (VI) were crucial for the quantitative remote sensing. In this study, the scale effects were investigated by analyzing the linear relationships between VI calculated from red-green-blue (RGB) images from unmanned aerial vehicles (UAV) and ground leaf chlorophyll contents of maize measured using SPAD-502.

Climate warming increases spring phenological differences among temperate trees.

Climate warming has substantially advanced spring leaf flushing, but winter chilling and photoperiod co-determine the leaf flushing process in ways that vary among species. As a result, the interspecific differences in spring phenology (IDSP) are expected to change with climate warming, which may, in turn, induce negative or positive ecological consequences. However, the temporal change of IDSP at large spatiotemporal scales remains unclear.

Advanced Estimation Techniques for Vehicle System Dynamic State: A Survey.

In order to improve handling stability performance and active safety of a ground vehicle, a large number of advanced vehicle dynamics control systems-such as the direct yaw control system and active front steering system, and in particular the advanced driver assistance systems-towards connected and automated driving vehicles have recently been developed and applied. However, the practical effects and potential performance of vehicle active safety dynamics control systems heavily depend on real-time knowledge of fundamental vehicle state information, which is difficult to measure directly in a standard car because of both technical and economic reasons. This paper presents a comprehensive technical survey of the development and recent research advances in vehicle system dynamic state estimation.

Shortened temperature-relevant period of spring leaf-out in temperate-zone trees.

Temperature during a particular period prior to spring leaf-out, the temperature-relevant period (TRP), is a strong determinant of the leaf-out date in temperate-zone trees. Climatic warming has substantially advanced leaf-out dates in temperate biomes worldwide, but its effect on the beginning and length of the TRP has not yet been explored, despite its direct relevance for phenology modeling. Using 1,551 species-site combinations of long-term (1951-2016) in situ observations on six tree species (namely, Aesculus hippocastanum, Alnus glutinosa, Betula pendula, Fagus sylvatica, Fraxinus excelsior, and Quercus robur) in central Europe, we found that the advancing leaf-out was accompanied by a shortening of the TRP.

Chlorogenic acid inhibits osteosarcoma carcinogenesis via suppressing the STAT3/Snail pathway.

Chlorogenic acid (CA) is a polyphenol compound that possesses anticancer effects on several types of tumors. However, there are few previous studies concerning the protective effects of CA on osteosarcoma. The current study aimed to examine the toxicity of CA to osteosarcoma cells and to explore the potential mechanisms.

Cesium carbonate-promoted synthesis of aryl methyl sulfides using S-methylisothiourea sulfate under transition-metal-free conditions.

In the presence of cesium carbonate, an efficient synthesis of aryl methyl sulfides by the reactions of aryl halides with commercially available S-methylisothiourea sulfate is developed. This odourless and highly crystalline solid can be used as the substitute for malodorous methanethiol. The gram-scale reaction also proceeds smoothly without the use of column chromatography separation.

Preparation and photophysical properties of thienothiophene functionalized difluoroboron bis-β-diketonate complexes.

A series of six new thienothiophene functionalized difluoroboron bis-β-diketonates were synthesized and characterized. Their photophysical properties were investigated by UV-vis absorption, fluorescence spectroscopy and the method of CIE chromaticity in solution and powders. The results showed that these difluoroboron complexes yielded a blue-green emission at 474-500 nm in DMF solution and emitted a green to yellow emission at 541-587 nm in powders.

A highly sensitive fluorescent chemosensor for selective detection of zinc (II) ion based on the oxadiazole derivative.

A novel fluorescent chemosensor based on the oxadiazole, 2-(2-hydroxyphenyl)-5-(4-methoxyphenyl)-1,3,4-oxadiazole, was designed and synthesized. The interaction of the oxadiazole with different metal ions had been investigated through UV-vis absorption and fluorescence spectra in 9:1 (v/v) ethanol-water (pH=7.0) solution.

Synthesis of 6-Substituted 6H-Indolo[2,3-b]quinolines from Isoindigos.

A facile approach to 6-aryl/alkyl substituted 6H-indolo[2,3-b]quinolines from mono-N-substituted isoindigo derivatives in the presence of SnCl·2HO in acid media is described. Pyrrole and pyridine rings are synchronously constructed in one pot for these tetracyclic molecules. A plausible reduction/hydrolysis/decarboxylation/cyclization/aromatization domino reaction mechanism is proposed.