Search

Herein, we present a unified chemical synthesis of three subgroups of cephalotaxus diterpenoids. Key to the success lies in adopting a synthetic strategy that is inspired by biosynthesis but is opposite in nature. By employing selective one‐carbon introduction and ring expansion operations, we have successfully converted cephalotane‐type C18 dinorditerpenoids (using cephanolide B as a starting material) into troponoid‐type C19 norditerpenoids and intact cephalotane‐type C20 diterpenoids. This synthetic approach has enabled us to synthesize cephinoid H, 13‐oxo‐cephinoid H, 7‐oxo‐cephinoid H, fortalpinoid C, 7‐epi‐fortalpinoid C, cephanolide E, and 13‐epi‐cephanolide E. Furthermore, through the development of an intermolecular asymmetric Michael reaction between β‐oxo esters and β‐substituted enones, we have achieved the enantioselective synthesis of advanced intermediates within our synthetic sequence, thus formally realizing the asymmetric total synthesis of the cephalotaxus diterpenoids family. [ABSTRACT FROM AUTHOR]

The inherently huge volume expansion during Li uptake has hindered the use of Si‐based anodes in high‐energy lithium‐ion batteries. While some pore‐forming and nano‐architecting strategies show promises to effectively buffer the volume change, other parameters essential for practical electrode fabrication, such as compaction density, are often compromised. Here we propose a new in situ Mg doping strategy to form closed‐nanopore structure into a micron‐sized SiOx particle at a high bulk density. The doped Mg atoms promote the segregation of O, so that high‐density magnesium silicates form to generate closed nanopores. By altering the mass content of Mg dopant, the average radii (ranged from 5.4 to 9.7 nm) and porosities (ranged from 1.4 % to 15.9 %) of the closed pores are precisely adjustable, which accounts for volume expansion of SiOx from 77.8 % to 22.2 % at the minimum. Benefited from the small volume variation, the Mg‐doped micron‐SiOx anode demonstrates improved Li storage performance towards realization of a 700‐(dis)charge‐cycle, 11‐Ah‐pouch‐type cell at a capacity retention of >80 %. This work offers insights into reasonable design of the internal structure of micron‐sized SiOx and other materials that undergo conversion or alloying reactions with drastic volume change, to enable high‐energy batteries with stable electrochemistry. [ABSTRACT FROM AUTHOR]

Silicon oxide‐graphite (SiOx‐G) composites are promising anode materials for building practical high‐energy Li‐ion batteries. To acquire long and safe operation of battery, extensive efforts are made to maintain stable Li storage of SiOx‐G against materials aging and the accompanied performance fade. While previous studies mostly focus on the cycling aging, the calendar aging occurred during battery storage at a high state of charge or high temperature has not received sufficient attention. In this work, a mechanism study on the calendar aging chemistry of fully lithiated SiOx‐G electrodes in half‐cells both at ambient and high temperature (60 °C) is performed. Unmodified SiOx is employed as active materials to inspect the change of thermodynamics properties in the bulk and at interfaces. By excluding the interference from cathode, it is revealed that besides aggravated parasitic reactions happening at interface, Li migration from the lithiated graphite to the vicinal SiOx particles is also responsible for calendar aging of SiOx‐G electrodes, and high‐temperature storage notably accelerates the aging process. This work enriches the fundamental understandings about the multifactor‐coupled aging process of anode materials and sheds lights on rational materials design toward improved calendar life of a high‐energy rechargeable battery. [ABSTRACT FROM AUTHOR]

Ether solvents with superior reductive stability promise excellent interphasial stability with high‐capacity anodes while the limited oxidative resistance hinders their high‐voltage operation. Extending the intrinsic electrochemical stability of ether‐based electrolytes to construct stable‐cycling high‐energy‐density lithium‐ion batteries is challenging but rewarding. Herein, the anion‐solvent interactions were concerned as the key point to optimize the anodic stability of the ether‐based electrolytes and an optimized interphase was realized on both pure‐SiOx anodes and LiNi0.8Mn0.1Co0.1O2 cathodes. Specifically, the small‐anion‐size LiNO3 and tetrahydrofuran with high dipole moment to dielectric constant ratio realized strengthened anion‐solvent interactions, which enhance the oxidative stability of the electrolyte. The designed ether‐based electrolyte enabled a stable cycling performance over 500 cycles in pure‐SiOx||LiNi0.8Mn0.1Co0.1O2 full cell, demonstrating its superior practical prospects. This work provides new insight into the design of new electrolytes for emerging high‐energy density lithium‐ion batteries through the regulation of interactions between species in electrolytes. [ABSTRACT FROM AUTHOR]

In order to solve problems of multi-wire and multi-point measuring mode used in ground freezing construction in China at present such as large cable dosage, complex wiring and installation, high cost and large transmitting waste of signal, the paper proposed a design scheme of monitoring system of ground freezing by use of 1-wire technology and introduced software and hardware designs of the system. Application of the system in freezing construction of submine of Zhangji Coal Mine verified stability and reliability of the system, but forecasting function of the system needs to be perfected and improved further.

An artificial "salt-in-polymer" SEI, composed of poly-(1,3-dioxolane) and high-modulus fluorinated products generated from the in situ decomposition of Li salts, was constructed on the surface of Li-MSiOx particles. This LiF-rich SEI helps to maintain the structural integrity of Li-MSiOx particles and improves the Li storage reversibility of the Li-MSiOx anode. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the effects of hsa‐miRNA‐143‐3p on the cytodifferentiation of human stem cells from the apical papilla (hSCAPs) and the post‐transcriptional regulation of Nuclear factor I‐C (NFIC). Methodology: miRNA expression profiles in human immature permanent teeth and during hSCAP differentiation were examined. hSCAPs were treated with miR‐143‐3p overexpression or silencing viruses, and the proliferation and odontogenic and osteogenic differentiation of these stem cells, and the involvement of the NFIC pathway, were investigated. Luciferase reporter and NFIC mutant plasmids were used to confirm NFIC mRNA as a direct target of miR‐143‐3p. NFIC expression analysis in the miR‐143‐3p overexpressing hSCAPs was used to investigate whether miR‐143‐3p functioned by targeting NFIC. Student's t‐test and chi‐square tests were used for statistical analysis. Results: miR‐143‐3p expression was screened by microarray profiling and was found to be significantly reduced during hSCAP differentiation (p <.05). Overexpression of miR‐143‐3p inhibited the mineralization of hSCAPs significantly (p <.05) and downregulated the levels of odontogenic differentiation markers (NFIC [p <.05], DSP [p <.01] and KLF4 [p <.01]), whereas silencing of miR‐143‐3p had the opposite effect. The luciferase reporter gene detection and bioinformatic approaches identified NFIC mRNA as a potential target of miR‐143‐3p. NFIC overexpression reversed the inhibitory effect of miR‐143‐3p on the odontogenic differentiation of hSCAPs. Conclusions: miR‐143‐3p maintained the stemness of hSCAPs and modulated their differentiation negatively by directly targeting NFIC. Thus, inhibition of this miRNA represents a potential strategy to promote the regeneration of damaged tooth roots. [ABSTRACT FROM AUTHOR]

In the applications of wireless power transfer for mobile devices, the pick-up of the wireless power transfer system often needs to be moved in and moved out. A sudden change in the system structure will cause high transient voltages or currents, which could damage the power electronic device of the capacitive power transfer (CPT). In addition, the standby power of the system will be too high to work after removing the pick-up. A CPT system with double T-type resonant networks has been proposed to address these problems. The steady-state models of the system without the pick-up and normal state conditions of it are established. The relationships between the resonant network parameters are analyzed, and a systematic circuit parameter design method is provided. The proposed CPT topology and the parameter design method have been verified by simulation and experiment. The system not only achieved self-protection under severe load change but also entered standby mode automatically after the pick-up was moved out. Besides, the system is restored to the normal state condition when the pick-up is moved in without additional detection and control circuitry. [ABSTRACT FROM AUTHOR]