By using water as the hydrogen source, an eco-friendly and practical protocol for the synthesis of Z -vinyl thiocyanates through ultrasound-promoted Brønsted acid ionic liquid-catalyzed ...hydrothiocyanation of activated alkynes under minimal solvent conditions has been developed. This process effectively avoids the use of organic solvents, metal catalysts and harsh reaction conditions. This reaction shows attractive characteristics such as operational simplicity, broad substrate scope with good to excellent yields, ease of scale-up and high energy efficiency and recyclable and reusable catalysts.
In recent years, artificial intelligence has promoted the rapid development of intelligence in various fields, with mechatronics being one of its hot research topics ...
Summary
Modern offshore wind turbines (OWTs) are constructed with increasingly long blades and slender towers to capture wind resources more effectively. Consequently, OWTs have become vulnerable to ...wind and sea wave excitations. Mitigations of unfavorable OWT vibrations have been extensively investigated, with the majority focusing on passive vibration control strategies with control performance sensitive to structural frequency changes. Nonlinear energy sinks (NESs) are regarded as effective vibration control methods because their broadband fashion is robust against variations in structural frequencies. A novel NES with an improved track profile that combines both second‐ and fourth‐order polynomials (Track II NES) is proposed in the present study to improve the vibration mitigation effectiveness of traditional Track I NES with a track profile of a fourth‐order polynomial only. Governing equations of a single‐degree‐of‐freedom system with Track II NES are first established, and an equivalent linearization method is adopted to optimize the track profile and damping of the Track II NES. Moreover, a detailed 3D finite element model of a representative 5‐MW OWT is developed. Control effectiveness of the Track II NES is examined under different structural stiffnesses and mean wind speeds and then compared with that of conventional tuned mass damper (TMD) and Track I NES. Numerical results showed that the Track II NES can effectively suppress displacement and acceleration responses of OWTs and outperform its counterpart Track I NES. Moreover, the Track II NES can obtain reduction ratios close to those of the TMD but with better robustness against the detuning effect.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The exonuclease activity of Apurinic/apyrimidinic endonuclease 1 (APE1) is responsible for processing matched/mismatched terminus in various DNA repair pathways and for removing nucleoside analogs ...associated with drug resistance. To fill in the gap of structural basis for exonucleolytic cleavage, we determine the APE1-dsDNA complex structures displaying end-binding. As an exonuclease, APE1 does not show base preference but can distinguish dsDNAs with different structural features. Integration with assaying enzyme activity and binding affinity for a variety of substrates reveals for the first time that both endonucleolytic and exonucleolytic cleavage can be understood by an induced space-filling model. Binding dsDNA induces RM (Arg176 and Met269) bridge that defines a long and narrow product pocket for exquisite machinery of substrate selection. Our study paves the way to comprehend end-processing of dsDNA in the cell and the drug resistance relating to APE1.
The intermolecular asymmetric radical oxidative C(sp3)−C(sp) cross‐coupling of C(sp3)−H bonds with readily available terminal alkynes is a promising method to forge chiral C(sp3)−C(sp) bonds because ...of the high atom and step economy, but remains underexplored. Here, we report a copper‐catalyzed asymmetric C(sp3)−C(sp) cross‐coupling of (hetero)benzylic and (cyclic)allylic C−H bonds with terminal alkynes that occurs with high to excellent enantioselectivity. Critical to the success is the rational design of chiral oxazoline‐derived N,N,P(O)‐ligands that not only tolerate the strong oxidative conditions which are requisite for intermolecular hydrogen atom ion (HAA) processes but also induce the challenging enantiocontrol. Direct access to a range of synthetically useful chiral benzylic alkynes and 1,4‐enynes, high site‐selectivity among similar C(sp3)−H bonds, and facile synthesis of enantioenriched medicinally relevant compounds make this approach very attractive.
Chiral benzylic alkynes and 1,4‐enynes can be obtained in a straightforward approach from commercially available terminal alkynes and a diverse range of compounds containing benzylic and allylic C−H bonds by using the title reaction. The success of this approach lies in newly designed anionic N,N,P(O)‐ligands bearing a stable chiral oxazoline and a pentavalent phosphine oxide that are generated in situ.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•Singularity analysis of sound signals was correlated to tool wear progression in milling.•The proposed denoising algorithm can improve the SNR while preserving singularity.•HE features are ...correlated to tool conditions and independent of most cutting parameters.
Manufacturing plays an important role since they are among the largest energy consumers in modern societies. With the enhancement of environmental protection and a severe shortage of energy and resources globally, sustainable manufacturing technology has been recognized as an important future trend of manufacturing industries. Tool wear is inevitable in manufacturing and affects the surface quality and geometric tolerance significantly. Therefore, a robust and efficient Tool Condition Monitoring (TCM) system is needed to maximize tool life, ensure work-piece quality and benefit the cost control of manufacturers. Even though lots of tool condition monitoring systems have been established using various sensors, there is still an urgent demand for a low-cost and simple setup system. This article presents a sound singularity analysis approach for TCM in milling; this approach has never been previously employed for milling tools. A de-noising algorithm based on Wavelet Transform Modulus Maxima (WTMM) estimation was proposed to eliminate noises and preserve singularities. Then a wavelet basis selection method was established for optimal sound singularity analysis. The singularity was estimated by Holder Exponents (HE). A full tool life-cycle milling experiments were conducted to obtain the sound signals. The mutual information method was employed to rank HE features. The Means, Standard deviations, Minima of estimated HEs and Quantities of singular points are found most correlated to tool conditions. Then a Support Vector Machine (SVM) model trained by these features for TCM has been proposed, achieving classification accuracy of 85%. Finally, the manufacturing sustainability of the TCM approach was evaluated by tracking and improving the usages of ten same type cutters in the CNC manufacturing plant. Experimental results indicate that this approach is efficient and capable of providing effective guidance on tool replacement, and can enhance the manufacturing sustainability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study investigates the compressive mechanical properties and energy absorption characteristics of three types of triply periodic minimal surface (TPMS) Ti6Al4V cellular structures fabricated by ...selective laser melting (SLM). Based on the SEM observation, the morphology of Ti6Al4V alloy sheet-based TPMS structures was observed, and imperfections of SLM-fabricated cellular structures were investigated. The quasi-static uniaxial compression tests were carried out, and the deformation behavior was recorded by a camera. The result indicated that the compressive mechanical properties had an approximately positive relationship with the relative density of TPMS structures. In addition, the revised Gibson-Ashby prediction models of three sheet-based TPMS structures were established by fitting the compression test results. Furthermore, finite element analysis (FEA) of the compression process was also conducted to facilitate analysis and understanding of the deformation mechanism for TPMS structures. The results also revealed that the energy absorption capacity of TPMS structures increased with the increase in the actual relative density. The mechanical properties, energy absorption, and relative density diagram of sheet-based Ti6Al4V alloy TPMS structures were established to systematically obtain the optimal relative densities of TPMS structures for specific load-bearing and energy absorption applications.
•The mechanical properties and deformation mechanisms of three types of TPMS sheet-based structures were investigated.•The Gibson and Ashby's models for the cellular structure were modified by re-fitting the compression results.•The energy absorption characteristics of Ti6Al4V alloy sheet-based TPMS cellular structures were studied.•Numerical simulations were conducted to calculate the strength and deformation mechanisms of sheet-based TPMS structures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
While long noncoding RNAs (lncRNAs) have been reported to play an important role in human cancer types, they remain poorly understood in papillary thyroid carcinoma (PTC). The aim of this study was ...to use genome-wide expression profiling to identify lncRNAs acting as competing endogenous RNAs (ceRNAs) in PTC. We constructed a ceRNA network based on our lncRNA microarray data and validated the correlation between myocardial infarction-associated transcript lncRNA (MIAT), miRNA-150-5p, and EZH2 in vitro and in vivo. We found 15 lncRNAs, 28 miRNAs, and hundreds of mRNAs involved in this ceRNA network. Splendid positive correlations were found between the MIAT and EZH2 expression in types of cancer in TCGA data. Besides, significant differences in MIAT/EZH2 expression were found among various clinicopathological features. Gain- and loss-of-function experiments revealed that MIAT inhibited cell proliferation and migration in vitro. Moreover, EZH2 was identified as a direct downstream target of miR-150-5p in PTC cells. Restoration of EZH2 expression partially abolished the biological effects of miR-150-5p. Furthermore, overexpression of MIAT was inversely correlated with miR-150-5p expression. Knockdown of MIAT produced significant behavioral alter maybe partly due to the function of the MIAT-150-5p-EZH2 network. Our findings suggest MIAT may inhibit EZH2 expression and promote PTC cell invasion via the miR-150/EZH2 pathway. Therefore, MIAT may serve as a valuable prognostic biomarker and therapeutic target for PTC.
A lithium-sulfur (Li-S) battery is regarded as the most promising candidate for next generation energy storage systems, because of its high theoretical specific capacity (1675 mA h g
) and specific ...energy (2500 W h kg
), as well as the abundance, low cost and environmental benignity of sulfur. However, the soluble polysulfides Li
S
(4 ≤ x ≤ 8) produced during the discharge process can cause the so-called "shuttle effect" and lead to low coulombic efficiency and rapid capacity fading of the batteries, which seriously restrict their practical application. Using porous materials as hosts to immobilize the polysulfides is proved to be an effective strategy. In this article, a dual functional cage-like metal-organic framework (Cu-MOF), Cu-TDPAT, combining the Lewis basic sites from the nitrogen atoms of the ligand H
TDPAT with the Lewis acidic sites from Cu(ii) open metal sites (OMSs), was employed as the sulfur host in a Li-S battery for lithium ions and polysulfide anions (S
). In addition, the size of nano-Cu-TDPAT was also optimized by microwave synthesis to reduce the internal resistance of the batteries. The electrochemical test results showed that the optimized Cu-TDPAT material can efficiently confine the polysulfides within the MOF, and the resultant porous S@Cu-TDPAT composite cathode material with the size of 100 nm shows good cycling performance with a reversible capacity of about 745 mA h g
at 1C (1C = 1675 mA g
) after 500 cycles, to the best of our knowledge, which is higher than those of all reported S@MOF cathode materials. The DFT calculation and XPS data indicate that the good cycling performance mainly results from the dual functional binding sites (that is, Lewis acid and base sites) in nanoporous Cu-TDPAT, providing the comprehensive and robust interaction with the polysulfides to overcome their dissolution and diffusion into the electrolyte. Clearly, our work provides a good example of designing MOFs with suitable interaction sites for the polysulfides to achieve S@MOF cathode materials with excellent cycling performance by multiple synergistic effects between nanoporous host MOFs and the polysulfides.
Monofluoroalkanes are important in many pharmaceuticals, agrochemicals and functional materials. However, the lack of easily available and transformable monofluoroalkylating reagents that facilitate ...a broad array of transformations has hampered the application of monofluoroalkylation. Herein, we report a general and efficient method of preparing diverse aliphatic monofluorides with monofluoroalkyl triflate as the synthetic scaffold. Using both nickel‐catalyzed hydromonofluoroalkylation of unactivated alkenes and copper‐catalyzed C−C bond formation, the general diversification of the monofluoroalkylating scaffold has been exhibited. The broad utility of this monofluoroalkylating reagent is shown by concise conversion into various conventional fluoroalkylating reagents and construction of monofluoro‐alkoxy, ‐alkylamino motifs with commercially available heteroatom‐based coupling partners.
A general method allows preparation of diverse monofluorides based on the monofluoroalkyl triflate scaffold. Both nickel‐catalyzed hydromonofluoroalkylation of unactivated alkenes and copper‐catalyzed monofluoroalkylation of Grignard reagents were studied. Further utilities including conversion into conventional fluoroalkylating reagents and construction of monofluoro‐alkoxy, ‐alkylamino motifs.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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