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The cross-dehydrogenative coupling (CDC) reaction is the most direct and efficient method for constructing α-tertiary amino acids (ATAAs), which avoids the pre-activation of C(sp 3 )-H substrates. However, the use of transition metals and harsh reaction conditions are still significant challenges for these reactions that urgently require solutions. This paper presents a mild, metal-free CDC reaction for the construction of ATAAs, which is compatible with various benzyl C-H substrates, functionalized C-H substrates, and alkyl substrates, with good regioselectivity. Notably, our method exhibits excellent functional group tolerance and late-stage applicability. According to mechanistic studies, the one-step synthesized and bench-stable N-alkoxyphtalimide generates a highly electrophilic trifluoro ethoxy radical that serves as a key intermediate in the reaction process and acts as a hydrogen atom transfer reagent. Therefore, our metal-free and additive-free method offers a promising strategy for the synthesis of ATAAs under mild conditions. The cross-dehydrogenative coupling (CDC) reaction is the most efficient method for constructing α-tertiary amino acids (ATAAs). Here, the authors present a mild, metal-free CDC reaction for the construction of ATAAs with good regioselectivity.

Molecular solar thermal (MOST) energy systems can be utilized for the absorption, storage, and release of energy from the ultraviolet (UV) band of the solar spectrum. In this study, we designed a molecular solar thermal energy storage and release device based on the photoisomerization reaction of azobenzene. The device was integrated with a parabolic trough solar system, broadening the absorption range of the solar spectrum. By utilizing a coated secondary reflector, the system achieved efficient reflection of ultraviolet (UV) light in the 290–490 nm range, while solid-state azobenzene enabled the conversion of photon energy into chemical energy for storage and release. Experimental results under winter outdoor conditions demonstrated that: the secondary reflector significantly enhanced UV light concentration; the molecular solar thermal energy device exhibited remarkable thermal efficiency. Under an average solar irradiance of 302.23 W·m−2, the device demonstrated excellent thermal performance, with the azobenzene reaching a peak temperature of 42.07 °C. The maximum heat release capacity was measured at 10.89 kJ·kg−1·m−1, while achieving a remarkable heat release power of 29.31 W·kg−1·m−1.

Spinibarbus caldwelli is an important freshwater economic fish in China. Owing to uncontrolled fishing, wild resources of S. caldwelli have decreased rapidly and may be on the verge of extinction. In this study, utilizing single-molecule real-time (SMRT) sequencing technology and chromatin interaction mapping (Hi-C) technologies, we assembled the first chromosome-scale genome for S. caldwelli about 1.77 Gb in size, with a contig N50 length of 11.83 Mb and scaffold N50 length of 33.91 Mb. In total 1.72 Gb (97.01%) of the contig sequences were anchored onto fifty chromosomes with the longest scaffold being 56.20 Mb. Furthermore, proximately 49.41% of the genome was composed of repetitive elements. In total, 49,377 protein-coding genes were predicted, of which 47,724 (96.65%) genes have been functionally annotated. The high-quality chromosome-level reference genome and annotation are vital for supporting basic genetic studies and will be contribute to genetic structure, functional elucidation, evolutionary inquiry, and germplasm conservation for S. caldwelli .

The heat storage and release performance of cascade phase change units are investigated numerically for users in Inner Mongolia’s severe cold region. Three schemes of phase change material combinations are thoroughly tested. We obtained a better material combination scheme S3 (palmitic acid + polyethylene glycol), which has higher heat storage capacity per unit mass, higher average heat flux, and better unit synchronisation performance, so that it is more suitable for solar heating and cascade heat storage units in cold regions of Inner Mongolia. This study takes into account the irradiation variation of typical days during the winter heating season. The results show that the palmitic acid and polyethylene glycol combination scheme has the highest total heat storage per unit mass. This scheme also performs well in the synchronisation of two-stage storage units. When compared to the other two schemes, the average heat flux is increased by 25.5% for the first stage unit and 16.8% for the second stage unit.

The electrorheological (ER) valve with parallel electrodes structure has an inherent characteristic. The electrodes gap is the same as its flow channel gap, which causes a strong coupling relationship between the applied voltages and the flow rates of the ER valve. If flow rates of ER valves in the condition of turn on operational mode were increased, their applied voltages were increased necessarily for keeping their shutdown operational mode, which brings a bunch of problems of product costs and dimensions, especially when multiple ER valves with different operational modes work together, such as application of ER valves matrix used in 2D matrix displays. The mesh electrodes structure can decouple the relationship between the electrodes gap and the flow channel gap of parallel electrodes structure. However, due to the complexity of mesh electrodes structure, a mathematic model is difficult to be established theoretically. And, a mathematic model of ER valve with mesh electrodes plays a vital role in designing its controller. By analyzing the composition elements of an ER valve with mesh electrodes, a semi experimental model was established using the parametric identification toolbox of MATLAB. The consistency between the output of recognition model and the output of validation data reaches 93.46%. Subsequently the PID controller for ER valves with mesh electrodes was designed to meet the operational demands of a 2D matrix display using Simulink. The constrain of simulation was that the pressures of flow channel inlets of ER valves, the dynamic responses of ER valves with mesh electrodes kept stable and within its operational range. The results will be helpful for applications of ER valves with mesh electrodes.

The pantograph-catenary arcing reflects the health of pantograph-catenary and current collection quality of high-speed railway, so the arc detection is of great significance. However, due to the scene complexity, intra-class polymorphism and inter-class similarity of arcing and the fast running speed of high-speed railway, it is still a huge challenge to achieve fine and robust arcing detection. To overcome these issues, a robust and fast image-based instance segmentation method called ArcMask is proposed to detect pantograph-catenary arcing, which designs a new attention-based multi-scale feature fusion module that combines both top-down and down-up modules to realize arcing pixel-level instance segmentation. The effective combination of instance-level information and bottom-level semantic information balances features representation ability of top-level and bottom-level features. Compared with other instance segmentation methods (e.g., BlendMask), it can effectively learn feature representation with tiny, irregular and complex arc features and speeds up the calculation. In addition, both deformable convolution and depth-wise separable convolution are introduced in ArcMask, which aims to improve the segmentation performance of irregular arcing and efficiency. The ArcMask can distinguish different arcing instances at pixel-level with fine granularity and distinguish inter-class and intra-class features of arcing, instead of just focusing on rectangular bounding box. Experiments on self-collected dataset IVAIS-PCA2021 verify the effectiveness and efficiencies of the ArcMask. Its AP, AP 50 and AP 75 are 56.61, 94.14 and 64.56, respectively, and the fastest reasoning speed based on MobileNet is 56 FPS. Compared with other state-of-the-art segmentation methods, the proposed ArcMask has better integrity in arcing edge detection.

Influence of area ratio (AR) on main performance parameters of solar chimney power plants (SCPPs) is investigated through a justified 3D axisymmetric CFD model. Geometric characteristics of Manzanares pilot plant (MPP) are taken into consideration for the numerical model. AR is varied from 0.5 to 10 to cover both concave and convex (convergent and divergent) solar chimney designs. Following the accuracy verification of the CFD results and proving mesh-independent solution, main performance oriented parameters are assessed as a function of AR such as velocity, temperature and pressure distribution within MPP, temperature rise of air in collector, mass flow rate of air around the turbine area, dynamic pressure difference across the turbine, minimum static pressure in the entire plant, power output and system efficiency. The results reveal that AR plays a vital role in performance figures of MPP. Mass flow rate of air ($\\dot{m}$) is found to be 1122.1 kg/s for the reference geometry (AR = 1), whereas it is 1629.1 kg/s for the optimum AR value of 4. System efficiency (η) is determined to be 0.29% for the reference case; however, it is enhanced to 0.83% for the AR of 4.1. MPP can generate 54.3 kW electrical power in its current design while it is possible to improve this figure to 168.5 kW with the optimal AR value.

Solar air heaters are at the centre of interest owing to their widespread use for various purposes. In the study, thermal performance analysis of a solar air heater that can be easily produced from daily waste materials is done. The system has a low-cost structure with both waste material use and a simple design. The proposed system is tested under different climatic conditions, and the energetic and the exergetic performance figures are obtained for the first time in literature. It is observed from the experimental tests that the results are stable and coherent as well as in good accordance with the similar attempts in literature with some cost reductions and performance improvements. Thermodynamic performance analyses indicate that the maximum energy efficiency of the system is about 21%, whereas the exergy efficiency is 1.8%. The energetic and exergetic outputs of the system are also determined to be 27 W and 3 W, respectively, which is promising.

The development of azobenzene photoisomerization materials marks a pivotal advancement in solar-thermal conversion technologies. Their properties and performance, explored through comprehensive characterization, are vital for further progress. Despite extensive research in this area, a detailed summary of characterization methods for azobenzene materials remains largely unexplored. This review addresses this gap by detailing structural and performance characterization techniques. It provides an in-depth overview of various experimental methods, highlighting their objectives, operational mechanics, and practical applications. This detailed review sheds light on the complex relationship between the materials’ structure and their performance. Moreover, the review presents a critical analysis of these methods, assessing their strengths and limitations. By doing so, it highlights the revolutionary potential of azobenzene materials in the realm of solar energy conversion and underscores their significance in fostering sustainable energy solutions.

Abstract The fact that energy sources are heavily dependent on fossil fuels increases the need for alternative energy day by day. Solar energy is the most popular alternative energy source with massive potential. Solar chimney power plants (SCPP) are one of the systems of interest based on solar energy. SCPP systems are rare systems that can provide 24-hour power output. Their performance has been the subject of constant research since the first pilot plant in Manzanares. Design is crucial for performance figures of SCPPs, and the limitation of climatic parameters causes the system to be approached with different designs. This study makes a 3D CFD model by combining the divergent chimney and convergent collector structure based on the first pilot plant. The solar ray tracing algorithm and the RNG k-e turbulence model are applied and the model equations are solved under dynamic conditions with the reliable software ANSYS FLUENT. After the mesh-independent solution of the model is complete, it is validated with experimental data. The two cases are compared for solar radiation of 1000 W/m2 and environmental temperature of 293 K. A power output of 50.51 kW is achieved for standard pilot sizing. With the new model, the power output rises to 146.34 kW. It is seen that the divergent chimney and convergent collector affect the airflow in the system, increasing the maximum air velocity to 19.363 m/s. In parallel with the experimental data, it is seen that the temperature on the ground exceeds 360 K in the CFD results.