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We report an enantioselective reductive cross coupling of electron-deficient olefins. Using a visible-light-driven cooperative photoredox and chiral Brønsted acid-catalyzed reaction with a Hantzsch ester as the terminal reductant, various cyclic and acyclic enones with 2-vinylpyridines were converted in high yields (up to 93%) to a wide range of enantioenriched pyridine derivatives featuring diverse γ-tertiary carbon stereocenters with good to excellent enantioselectivities (up to99% ee).

By switching on visible blue light, aerobic oxidation of various substrates, such as α-substituted, β-substituted and α-halo styrenes, was first realized with a copper(ii) catalyst.

Overall, the electric vehicle transmission system shows an underdamped characteristic. Under changeable road conditions and high-frequency response for the motor, the resulting dynamic load environment may cause multiple failure modes, such as contact fatigue failure and bending fatigue fracture, for the transmission component, which limits the electric vehicle transmission component lifespan and system reliability. To reflect the dynamic load characteristics of the electric vehicle transmission system using a permanent magnet synchronous motor as a power source and accurately calculate the dynamic load of the transmission system, a high-speed helical gear-rotor-bearing coupling mechanical model for the electric vehicle transmission system was built based on simulating actual operation working conditions of the electric vehicle and considering the external load excitation caused by the Electromagnetic torque of the permanent magnet synchronous motor and vehicle driving resistant change as well as internal excitation caused by gear time-varying meshing rigidness and meshing error. Through simulation calculation of the mechanical model, the dynamic meshing force of the gear pair and dynamic contact force of the support bearing was obtained. Based on the Hertz contact theory, the stress-time history was obtained for the key parts, the rain flow counting method was adopted for the statistics collection and analysis of the stress-time history, and the fatigue load spectrum for various key parts of the transmission system was obtained. The result lays a foundation for the fatigue life prediction and reliability analysis for the pure electric vehicle transmission system.

A chiral Brønsted acid catalysed phosphine-mediated deoxygenation protocol is reported. This metal-free method provides a precise kinetic resolution platform for azaarylethynyl tertiary alcohols, which are a broad category of biologically and synthetically important azaarene derivatives. In addition to providing an efficient method for the first asymmetric preparation of these tertiary alcohols, the strategy facilitates the construction of azaaryl-functionalized allenes with good to excellent enantioselectivities. The high selectivity factors (s up to 235), broad substrate scope, and ability to convert azaaryl compounds into both chiral tertiary alcohols and allenes robustly underscore the efficiency and promising utility of this method. The practicability is further validated by the successful synthesis of deuterated allenes with high ee values and substantial incorporation of deuterium using inexpensive D

As the anode materials of lithium-ion battery, the hard carbon has the higher power performance while the graphite has the higher energy performance, respectively. In this work, novel mixed hard carbon/graphite anodes are presented showing the coupling effect of power and mixed anodes was investigated at the varying charging rates, showing the tunable behaviors dependent on the hard carbon/graphite ratios. By studying the specific capacity evolution in different split potential ranges, we found that the mixed anodes with a higher proportion of hard carbon were advantageous when working in the cut-off potential greater than 0.10 V. The electrochemical impedance spectroscopy was measured at various anode potentials, which depicted the evolution of cell resistance with the state of charge. With the aid of electrochemical impedance spectroscopy, we found that the capacity evolution with mixed ratio is attributed to the lithiation-level induced difference of charge transfer resistance and Warburg resistance. A coupling effect was discovered showing a great potential in balancing the power-energy performance of mixed anode by simply controlling the ratio of hard-carbon/graphite.

A radical-based asymmetric olefin difunctionalization strategy for rapidly forging all-carbon quaternary stereocenters α to diverse azaarenes is reported. Under cooperative photoredox and chiral Bronsted acid catalysis, cyclopropylamines with α-branched 2-vinylazaarenes can undergo a sequential two-step radical process, furnishing various valuable chiral azaarene-substituted cyclopentanes. The use of the rigid and confined C2-symmetric imidodiphosphoric acid catalysts achieves high enantio- and diastereo-selectivities for these asymmetric [3 + 2] cycloadditions.

Chiral hydrogen-bonding (H-bonding) catalytic asymmetric conjugate addition to activated olefins has been widely used to access enantioenriched molecules containing stereocenters at the β-position of the olefin activating groups. Herein, we report the first highly enantioselective radical-based manifold. Under a dual organocatalyst system involving a chiral phosphoric acid and DPZ as the photoredox sensitizer, transformations of N-arylglycines, in which aryls with CF

The drive range of electric vehicle (EV) is one of the major limitations that impedes its universalism. A great deal of research has been devoted to drive range improvement of EV, an accurate and e...

3-Nitramino-6-hydroxy-1,2,4,5-tetrazine (NHTZ) and its alkaline earth metal salts (Mg2+(1), Ca2+(2), Sr2+(3), Ba2+(4)) were prepared via 3,6-dinitramino-1,2,4,5-tetrazine for the first time. The electrostatic potentials and HOMO-LUMO orbitals of them were computed to better understand the electronic structure of NHTZ. Structures of the four alkaline earth metal salts were confirmed by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Structural analysis revealed that all compounds have differently dimensional structures, increasing with the radius of metal atoms. Compounds 3 and 4 can be classified as coordination polymers due to their structural features. As the only 3D polymeric structure in this series, compound 4 possesses the highest density and best thermal stability in these compounds. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) measurement shows the excellent thermal stability of these salts, with the thermal decomposition temperatures of 291.1°C (1), 294.1°C (2), 294.9°C (3) and 324.7°C (4). Heat of formation and sensitivity of the four salts were investigated, which suggest 4 as a potential heat-resistant energetic compound instructions for authors.

Chiral hydrogen-bonding catalysis is a classic strategy in asymmetric organocatalysis, and it has been extensively used in a variety of fundamental chemical transformations. At the same time, visible light-driven photoredox catalysis is a powerful and sustainable tool commonly used in radical chemistry. The intriguing combination of these two catalysis platforms would open a new avenue for the direct and highly efficient synthesis of enantioenriched compounds. Inspired by the conceptual breakthrough of T. Bach, in recent years, significant progress has been made in cooperative photoredox and chiral hydrogen-bonding catalysis. By developing a variety of important types of reactions, a wide range of valuable chiral compounds have been successfully synthesized. In this review, the advances in this key area are systematically described, and the examples are organized according to the distinct bond-forming patterns in the construction of the stereocentres.

2-Hydroxymethyl-5-(2-hydroxymethyl-tetrazole-5-yl)-triazole (2) was designed and obtained in a good yield by the reaction of (tetrazol-5-yl)-triazole (1) with formaldehyde in the presence of 20% H2SO4. Three dimensional (3D) energetic metal complexes, sodium and potassium salts of 1 and 2 (3 and 4 for 1 and 5 and 6 for 2, respectively), were synthesized and thoroughly characterized. The crystal structures of 2–6 were confirmed by using single crystal X-ray diffraction. Because of the presence of hydroxymethyl in 2, 5 and 6 formed fascinating 3D supramolecular network architectures, which show more remarkable closer packing and higher density than 3 and 4. All the compounds are insensitive to impact and friction, and exhibit high thermal stabilities. The Hirshfeld surface calculation reveals that 2 has strong intermolecular interactions. In these cases, the method of introducing hydroxymethyl into energetic nitrogen-rich heterocyclic compounds results in superior structure and performance.

Wheelset bearings are crucial mechanical components of high-speed trains. Wheelset-bearing fault detection is of great significance to ensure the safety of high-speed train service. Convolution sparse representations (CSRs) provide an excellent framework for extracting impulse responses induced by bearing faults. However, the performance of CSR on extracting impulse responses is fairly sensitive to inappropriate selection of method-related parameters, and a convolution model for representing the impulse responses has not been discussed. In view of these two unsolved problems, a convolutional representation model of the impulse response series is developed. A novel fault detection method, named adaptive CSR (ACSR), is then proposed based on combinations of CSR and methods for estimating three parameters related to CSR. Finally, the effectiveness of the proposed ACSR method is validated via simulation, bench testing, and a real-life running test employing a high-speed train.

The lithium-ion batteries powering mass market electric vehicles must be capable of operating in a wide temperature range. Temperature variation has the potential to greatly affect the stability of...

In view of the problem that hybrid electric vehicle (HEV) platoon energy management cannot adapt to working condition and online implementation, this paper proposes hierarchical model predictive control strategy based on Q-Learning algorithm. Firstly, the upper-level controller obtains the speed and position information of the preceding vehicle by vehicle-to-vehicle (V2V) communication. Model predictive control (MPC) is implemented to achieve platoon longitudinal control. The target speed of following vehicle is calculated and transmit to the driver model. Then, the driver’s power demand is figured out on the basis of the difference between target and actual speed. The lower-level controller uses the Q-learning algorithm to allocate the energy of HEV platoon based on driver’s power demand and state of charge (SOC) at the current moment. Finally, the simulation model of Chongqing Yubei actual working condition is established by using MATLAB/Simulink software. The simulation results show that in the upper-level controller, the average speed error between No. 1 following vehicle and the leading vehicle is 0.167 m/s, and the average speed error between No. 2 following vehicle and No. 1 following vehicle is 0.153 m/s. Meanwhile, the spacing between the platoon vehicles is always kept within a reasonable range. These will ensure good following and driving safety of the platoon. In the lower-level controller, compared with dynamic programming (DP), the average fuel consumption per 100 km of the vehicle with the Q-learning algorithm is increased by 7.67%, but the offline calculation time is reduced by 23%. The results indicate the proposed strategy can not only adapt to random condition but also be realized online for HEV platoon.

The wheelset-bearing system is one of the most critical subsystems in a high-speed train. Detecting faults is significant for ensuring the operational safety of a high-speed train. The key to detect a wheelset-bearing system fault is to extract the weak and periodic impulse responses (WPIRs) from the collected acceleration signals of the axle box. To improve the poor performance of the tunable Q-factor wavelet transform (TQWT) in extracting WPIRs, a multi-Q-factor (MQ), multi-level (ML) tunable Q-factor wavelet transform (MQML-TQWT) with an almost constant bandwidth characteristic is proposed. The optimal decomposition bandwidth and decomposition level of the MQML-TQWT are automatically selected based on the maximal envelope spectral kurtosis (MESK). The MQML-TQWT with the optimal decomposition bandwidth and decomposition level is used to extract WPIRs. The proposed method is verified by simulated signals and vibration signals measured from a wheelset-bearing system test bench. The results indicate that the MQML-TQWT effectively extracts WPIRs that may be associated with early faults in the wheelset-bearing system and is superior to the existing TQWT in extracting WPIRs.

Toluene and its derivatives are petroleum-derived raw materials produced from gasoline by catalytic reformation. These abundant chemical feedstocks are commonly used as solvents in organic synthesis. The C(sp3)−H functionalization of these unactivated substrates has been widely used to directly introduce benzylic motifs into diverse molecules to furnish important compounds. Despite these advances, progress in asymmetric catalysis remains underdeveloped. Here, we report photoinduced radical-based enantioselective C(sp3)−C(sp3) coupling reactions of activated ketones with toluene and its derivatives by means of chiral acid catalysis. With a La(OTf)3/pybox complex catalyst, a variety of chiral 3-hydroxy-3-benzyl-substituted 2-oxindoles, including many conventionally difficult-to-access variants, are obtained directly from isatins in high yields with good to excellent enantioselectivities. Acenaphthoquinone is also compatible with the use of a chiral phosphoric acid (CPA) catalyst, leading to another series of important enantioenriched tertiary alcohols., Asymmetric transformations involving abundant chemical feedstocks such as toluene and its derivatives are rather rare. Here, the authors report the radical enantioselective C(sp3) −C(sp3) coupling of activated ketones with toluenes by means of chiral acid catalysis to afford enantioenriched tertiary alcohols.

To provide a favorable temperature for a Li-ion battery liquid cooling system, novel leaf-like channels with loops were designed as the dispersed layer. Furthermore, four collection channels along diagonal lines were established to decrease the temperature gradient, which formed a double-layer cooling channel. The effects of four structural parameters (width ratio, length ratio, bifurcation angle and channel thickness) on maximum temperature and surface standard deviation were investigated. In addition, the influence of the inlet mass flow rate was also discussed. The obtained results demonstrated that optimal maximum temperature and temperature uniformity were achieved at a width ratio of about 3/4, a length ratio close to 0.5 and a bifurcation angle in the range of 30–50°. Moreover, the thickness of the cooling channel had a strong effect on the pressure drop but only a little on the heat transfer. Increasing inlet mass flow rate can obtain the required heat dissipation capacity but at the expense of pressure drop. In summary, the synergistic effect of thickness and inlet mass flow rate can satisfy the requirements of both heat dissipation and power consumption. This optimized design can decrease the maximum temperature from 60 °C to 32 °C and the standard deviation of surface temperature from 7.1 °C to 1.4 °C. These simulation results are helpful for the design of cold plates with fractal networks.

A formal [3+2] cycloaddition of N-aryl α-amino acids with isoquinoline N-oxides via visible light-driven photoredox catalysis is reported. Under transition metal-free conditions using a dicyanopyrazine-derived chromophore (DPZ) as the photoredox catalyst, the transformation was efficient and led to a series of important diazabicyclo[3.2.1]octane-based N-heterocyclic compounds. This work demonstrates the synthetic utility of N-aryl α-amino acids as 1,2-synthons and provides a new strategy for the dearomatization of isoquinolines.

A stable solid electrolyte interphase (SEI) has been proven to be a key enabler to most advanced battery chemistries, where the reactivity between the electrolyte and the anode operating beyond the electrolyte stability limits must be kinetically suppressed by such SEIs. The graphite anode used in state-of-the-art Li-ion batteries presents the most representative SEI example. Because of similar operation potentials between graphite and silicon (Si), a similar passivation mechanism has been thought to apply on the Si anode when using the same carbonate-based electrolytes. In this work, we found that the chemical formation process of a proto-SEI on Si is closely entangled with incessant SEI decomposition, detachment, and reparation, which lead to continuous lithium consumption. Using a special galvanostatic protocol designed to observe the SEI formation prior to Si lithiation, we were able to deconvolute the electrochemical formation of such dynamic SEI from the morphology and mechanical complexities of Si and showed that a pristine Si anode could not be fully passivated in carbonate-based electrolytes.

An enantioselective cascade aerobic oxidation and semipinacol rearrangement reaction of 2-aryl-3-alkyl-substituted indoles via visible-light-driven cooperative organophotoredox and H-bonding catalysis is reported. The current method provides an expedient and sustainable approach to furnish a variety of valuable chiral 2-aryl-2-alkyl-substituted indolin-3-ones in 64-90 % yield with 58-94 % ee. Preliminary control experiments present important insights into the stereochemistry.