Impressive progress has been made in the copper‐catalyzed asymmetric propargylic substitution (APS) reaction, but its use in remote asymmetric yne‐allylic substitution remains a challenging topic. ...Herein, we report the first remote enantioselective copper‐catalyzed sulfonylation of yne‐allylic esters with sodium sulfinates. The reaction is assumed to occur via a copper‐vinylvinylidene species as the key reactive intermediate. The use of readily available starting materials, the mild reaction conditions, and the excellent regio‐, enantio‐ and stereoselectivity, as well as broad substrate scope (>70 examples), show the practicality and attractiveness of this method.
An enantioselective copper‐catalyzed reaction was developed for the sulfonylation of yne‐allylic esters with sodium sulfinates. Salient features of this practical method include readily available starting materials, mild reaction conditions, excellent regio‐, enantio‐ and diastereoselectivity, as well as broad substrate scope.
•Expand the creep-fatigue life sample size by divide-and-conquer machine learning.•Probabilistic damage distributions are explored to depict the scatter characteristics.•Establish probabilistic ...creep-fatigue damage assessment diagram.
In order to investigate the probabilistic damage distribution under creep-fatigue interaction, machine learning framework with the divide-and-conquer methodology is proposed to expand the creep-fatigue life sample size of each load condition. The optimized deterministic life prediction model, strain energy density exhaustion model (SEDE), is selected to take material variability into account. Subsequently, random accumulated creep and fatigue damage are obtained by the combination of probabilistic SEDE life model and creep-fatigue life distributions through the Latin hypercube sampling (LHS) simulation. A relative scatter factor depicted in the creep-fatigue interaction diagram is introduced to reveal the dominance of scatter in creep/fatigue on life scatter. Consequently, a probabilistic creep-fatigue damage assessment diagram with involving probabilistic equipotential line for safety evaluations is established. Such probabilistic damage assessment may provide reference and has promising potential in the further creep-fatigue life design for reliability.
Soft actuators have received intensive attention in the fields of soft robots, sensors, intelligent control, artificial intelligence, and visual intelligence. By combination of tensile and torsional ...deformations, different types of motions can be realized, such as bending, rolling, and jumping. Soft robotics need soft actuators, such as artificial muscles to lift or move objects to perform some work. Additionally, actuation integrated with functions of sensing, signal transmission, and control is also needed in the development of advanced intelligent systems, which further stimulates the requirement of multifunctional actuators. Here different types of soft actuators that can perform tensile and torsional actuations are summarized, including twisted fiber artificial muscles, shape memory polymers, hydrogels, liquid crystal polymers, electrochemical actuators with conducting polymers, and some natural materials. Examples are also included regarding the bending or rolling deformations of the actuators for lifting objects. Then, recent interesting reports about multifunctional soft actuators combined with sensing and signal transmission performances, are summarized. Last, a summary of different ways to realize tensile and torsional actuations, different materials, and designs for lifting or moving objects, as well as construction of multifunctional actuators with actuation and sensing functions is provided.
The recent progresses of tensile and torsional soft actuators are summarized, including the actuation mechanisms, performances, fabrication methods, and applications of soft actuators prepared with different configurations and materials, as well as multifunctional actuators. Existing problems and perspectives are also discussed for the design and fabrication of high performance soft actuators.
•Framework for fatigue reliability analysis under multi-source uncertainties.•Manufacturing errors/tolerances are included for fatigue reliability analysis.•Sensitivity analysis of a turbine bladed ...disk is conducted for fatigue design.•Geometrical uncertainty shows critical influences on fatigue reliability.
Turbine bladed disks normally operate under complex loadings coupling with uncertainties originate from multiple sources, including material variability, load variation and geometrical uncertainty. The influence of these uncertainties on mechanical response of engineering components are critical for their fatigue assessment and reliability evaluation. In this work, a general framework for fatigue reliability analysis is developed by coupling the Latin hypercube sampling with FE analysis to describe the combined effects of multi-source uncertainties. Fatigue reliability analysis of a full-scale bladed disk under multi-source uncertainties was performed as well as sensitivity analysis for fatigue design. In order to describe the manufacturing errors or tolerances, random dimensions are inputted. Comparing the predicted fatigue lifetime distributions with/without geometrical uncertainty, it shows that geometrical uncertainty matters in structural fatigue reliability. Particularly, sensitivity analysis indicates that the geometrical uncertainty exerts more critical influences on the fatigue lifetime and reliability of the turbine bladed disk than others. The sensitivity factors of three typical dimensions emerges the influence of designed sizes and dimensional tolerances on the failure probability, which provides a reference for engineering design.
Urinary glucose determination using a glucose test strip is simple and convenient in daily self-monitoring of diabetes. However, diabetic patients exhibit acquired impaired color vision (ICV), which ...results in the inability to discriminate between hues. Even with the assistance of a color chart, it is still not easy for these patients to read the urinary glucose results with the naked eye. In this study, a smartphone camera using an image-based colorimetric detection method was successfully developed for quantitative analysis of urine glucose. A horseradish peroxidase-hydrogen peroxide-3,3′5,5′-tetramethylbenzidine (HRP–H2O2–TMB) system was optimized for a reliable and gradual color fading process via a glucose oxidase (GOD) catalyzed oxidation reaction. The color changes of the peroxidase-H2O2 enzymatic reactions in the 96-well microplate were captured by a smartphone RGB camera with subsequent detection of red, green, and blue (RGB) intensities decreasing at each image pixel. The highly quantitative relationships between the glucose concentrations and the color characteristic values of the blue channel of the captured images were successfully established. The high accuracy of this method was demonstrated in urine glucose measurements with a linear response over the 0.039 mg mL−1 to 10.000 mg mL−1 glucose concentration range and a 0.009 mg mL−1 detection limit. The method has great potential as a point-of-need platform for diabetic patients with defective color vision and features high accuracy and low cost.
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•Colorimetric detection capable of quantitative analysis with a regular smartphone.•Can be detected both visually by the naked eye and by a smartphone.•A point-of-need platform for uninary glucose at a high accuracy, but a low cost.•Feasible option for diabetics with impaired color discrimination in daily self-monitoring.
Upregulated expression of immune checkpoint molecules correlates with exhausted phenotype and impaired function of cytotoxic T cells to evade host immunity. By disrupting the interaction of PD-L1 and ...PD1, immune checkpoint inhibitors can restore immune system function against cancer cells. Growing evidence have demonstrated apigenin and luteolin, which are flavonoids abundant in common fruits and vegetables, can suppress growth and induce apoptosis of multiple types of cancer cells with their potent anti-inflammatory, antioxidant and anticancer properties. In this study, the effects and underlying mechanisms of luteolin, apigenin, and anti-PD-1 antibody combined with luteolin or apigenin on the PD-L1 expression and anti-tumorigenesis in KRAS-mutant lung cancer were investigated. Luteolin and apigenin significantly inhibited lung cancer cell growth, induced cell apoptosis, and down-regulated the IFN-γ-induced PD-L1 expression by suppressing the phosphorylation of STAT3. Both luteolin and apigenin showed potent anti-cancer activities in the H358 xenograft and Lewis lung carcinoma model in vivo, and the treatment with monoclonal PD1 antibody enhanced the infiltration of T cells into tumor tissues. Apigenin exhibited anti-tumor activity in Genetically engineered KRASLA2 mice. In conclusion, both apigenin and luteolin significantly suppressed lung cancer with KRAS mutant proliferation, and down-regulated the IFN-γ induced PD-L1 expression. Treatment with the combination of PD-1 blockade and apigenin/luteolin has a synergistic effect and might be a prospective therapeutic strategy for NSCLC with KRAS-mutant.
•Luteolin and apigenin can downregulate the PD-L1 expression in NSCLC with KRAS mutation.•The combination of apigenin or luteolin with PD-1 mAb enhanced tumor growth control and improved survival.•Apigenin but not luteolin exhibited anti-tumor activity in KRASLA2 mice.
A simple and rapid instantaneous nebulization dispersive liquid-phase microextraction method was developed, and combined with high-performance liquid chromatography for determination of the contents ...of seven analytes in traditional Chinese medicines. In this study, using the sprinkler device to achieve instantaneous synchronous dispersion and extraction, only one spray can rapidly achieve the concentration and enrichment of seven kinds of chalcone and isoflavones. The key factors affecting the extraction efficiency were optimized including the type and volume of extractant, the pH and salt concentration of the sample phase, and the number of dispersion. Under the optimal conditions, the enrichment factor of the target analytes ranged from 103.1 to 180.9, with good linearity and correlation coefficients above 0.9970. The limits of detection ranged from 0.02 to 0.15 ng/mL, with good accuracy (recoveries 91.1 to 108.9%) and precision (relative standard deviations 1.5-7.1%). This method has short extraction time (2 s), low organic solvent consumption and high enrichment effect, so it has a wide application prospects.
Sampling is an effective approach to cardinality estimation which in turn is a key to query optimization in a DBMS. Although there have been a lot of studies on applying machine learning to ...cardinality estimation recently, enhancing sampling-based cardinality estimation by machine learning has been overlooked for a long time. In this paper, we propose a new sampling-based cardinality estimation method called LDSS by developing a learning-based dynamic sample selection method. Unlike the existing sampling-based methods that perform online sampling for every query, our method selects for the query the most suitable sample from the set of samples of various sizes that have been materialized during preprocessing. The cardinality of the query is then estimated based on the selected sample. Since our method is based on sampling, it can handle both single-table queries and join queries. Due to dynamic sample selection, costly online sampling is completely avoided. By learning the complex relationships between samples and queries, our learned sample selector can recommend small yet good samples for input queries. The extensive evaluation performed on the benchmarks indicates that LDSS can be trained much faster and can achieve higher accuracy than the state-of-the-art query-dependent methods and comparable accuracy to the current data-driven methods.
•We propose the first cardinality estimation framework using dynamic sample selection.•We propose LDSS, a learning-based approach to dynamic sample selection.•We develop a method to incrementally update the learned sample selection model.•We experimentally evaluated the performance of LDSS using a set of benchmarks.•LDSS can achieve better accuracy than the state-of-the-art query-dependent methods.
•Explore degradation of material mechanical properties in creep-fatigue process.•A damage variable Dm is defined based on tensile plastic strain energy density.•Critical values of damage summation ...rules degrade as a power function of Dm.•3D damage diagram is constructed for evaluating creep-fatigue damage level.
Progressive degradation of material mechanical properties in the low cycle fatigue (LCF) and creep-fatigue (CF) interaction at high temperature affects the safe operation of in-service materials. By considering material degradation, the present work aims to establish a method for evaluating LCF and CF damage levels with wide applicability. Material-level data accumulations as well as theoretical foundations of LCF and CF are presented, including interrupted LCF and CF tests, subsequent tensile tests and energy-based damage models. A damage variable representing the degradation of material mechanical properties is then defined based on the tensile plastic strain energy density (TPSED), the physical mechanism of which is reflected in the microstructure evolution and fracture appearance. By taking into consideration the material degradation threshold in the traditional damage summation rule, a new three-dimensional (3D) damage interaction diagram is established, where the additional third axis indicates the material degradation level. Finally, taking GH4169 alloy and P92 steel as examples, this work demonstrates the implemented procedures of damage level evaluation, which has been validated via the experimental data.
