An estimation framework of regional rooftop photovoltaic potential based on satellite remote sensing images

This paper proposes a comprehensive framework for estimating the regional rooftop photovoltaic(PV)potential.The required rooftop information is extracted from Gao Fen-7 satellite images.In particular,the rooftop area is obtained using a semantic segmentation network.The azimuth and inclination angles are calculated based on the digital surface model.In addition,to improve the accuracy of the economic evaluation,buildings are divided into commercial and industrial buildings and residential buildings.Based on the difference in the roof inclination,the rooftops can be divided into flat roofs,on which the PV panels are installed with the optimal inclination angle,and sloped rooftops,on which the PV panels are installed in a lay-flat manner.The solar irradiation on the plane-of-array is calculated using the isotropic sky translocation model.Then,the available installed capacity and generation potential of the rooftop PV is obtained.Finally,the net present value,dynamic payback period,and internal rate of return are used to evaluate the economic efficiency of the rooftop PV project.The proposed framework is applied in the Da Xing district of Beijing,China,with a total area of 546.84 km^(2).The results show that the rooftop area and available installed capacity of PV are 25.63 km^(2)and 1487.45 MWp,respectively.The annual rooftop PV generation potential is 2832.23 GWh,with significant economic returns.

Circularly polarized luminescence switch based on a photochromic europium(Ⅲ) helicate derived coordination polymer

Chiroptical switches based on circularly polarized luminescence(CPL)have shown the promising applications in advanced information technologies.Herein,a pair of lanthanide coordination polymer enantiomers[Eu_(2)(L^(R))_(3)(BTFPO)_(2)]_(n) and[Eu_(2)(L^(S))_(3)(BTFPO)_(2)]_(n) with light-regulated CPL property are designed,which are assembled by a chiral binuclear triple-stranded Eu^(3+) helicates[Eu_(2)(L^(R/S))_(3)]coordinated with two photochromic triphenylphosphine oxides(BTFPO).Upon the alternative UV and 526 nm light irradiation,the complexes show the reversible photochromism,PL and CPL responses.Notably,the luminescence dissymmetry factor,g lum of ^(5)D_(0)→^(7)F_(1)(591 nm)transition shows an obvious increase from 0.19 to 0.29 before and after 275 nm light irradiation.Additionally,the emission from Eu^(3+) center is not completely quenched in closed-ring state due to the low photocyclization(Ф_(o-c))quantum yield of the polymer.The partial maintenance of emissive intensity is of essential importance for the monitor of CPL signal.More importantly,the CPL photo-switching property of the complexes in solid hybrid film is maintained,and still displays the enhanced CPL emission in photostationary state.Further,the potential applications of the doping film in logic gate and anti-counterfeiting were investigated.

丙烯酸酯三嵌段共聚物改性环氧树脂及其性能

通过原子转移自由基聚合(ATRP)法合成了硬-软-硬结构的ABA型嵌段共聚物(PMG-PBA-PMG)。采用核磁共振波谱仪、凝胶渗透色谱仪、傅里叶变换红外光谱仪分析确定了嵌段共聚物分子的结构及成分。利用嵌段共聚物改性环氧树脂,研究其热性能、流变学性能、力学性能、微观形貌、相容性及增韧机制。结果表明,丙烯酸酯三嵌段共聚物用量为10 phr时,共混体系的综合性能达到最佳,确定体系固化工艺为150℃×1 h+180℃×3 h;缺口冲击强度可达7.34 k J/m2,弯曲强度118 MPa,断裂伸长率4.8%,拉伸强度为80 MPa,弹性模量为2931 MPa;共混体系保持较宽的温度加工窗口,可作为复合材料预浸料树脂基体;此外,扫描电镜断面出现大量的锯齿,可有效阻碍裂纹的扩展并吸收大量的断裂能,从而提高环氧树脂的韧性。

石墨微片/硼粉对环氧树脂体系性能的影响

采用石墨微片和硼粉的复合体系制备了一种环氧树脂导电胶膜。通过绝缘测试仪、拉力试验机等对胶膜的电性能及力学性能进行了表征。结果表明,随着石墨与硼粉量的增加,电阻值和剪切强度呈明显下降的趋势。当石墨、硼粉用量分别为14.5 phr和20 phr时,胶膜的电阻值约为100 MΩ,剪切强度约为20 MPa。扫描电镜照片发现石墨微片呈片层结构分布在树脂体系中,有利于导电网络的构建;胶膜的体积电阻率和表面电阻率分别为7.29×10^7Ω·m、1.26×10^9Ω;胶膜的玻璃化转变温度约为125℃;5%热失重温度达到了347℃;固化后的胶膜具有保持自身形状的特性,且在120℃具有较宽的加工工艺窗口;该导电胶膜有望在复合材料防雷击保护等方面获得应用。

Research on Phase-Shifted Full-Bridge Circuit Based on Frequency and Phase-Shift Synthesis Modulation Strategy

The full-bridge converters usually use transformer leakage inductance and parallel resonant capacitors to achieve smooth current commutation and soft switching functions,which can easily cause problems such as energy leakage and significant duty cycle loss.This paper designs a novel full-bridge zero-current(FB-ZCS)converter with series resonant capacitors and proposes a frequency and phase-shift synthesis modulation(FPSSM)control strategy based on this topology.Compared with the traditional parallel resonant capacitor circuit,the passive components used are significantly reduced,the structure is simple,and there is only a slight energy loss.By controlling the charging time of the capacitor,it can be achieved without additional switches or auxiliary circuits.The automatic control of capacitor energy based on input current addresses the low efficiency of the traditional control strategies.This paper introduces its principle in detail and verifies it through simulation.Finally,an experimental prototype was built further to demonstrate the feasibility of the theory through experiments.The module can be applied to a photovoltaic DC collection system using input parallel output series(IPOS)cascade to provide a new topology for large-scale,long-distance DC transmission.

The General Dabrowski-Sitarz-Zalecki Type Theorem for Odd Dimensional Manifolds with Boundary II

In[T.Wu et al.,arXiv2310.09775,2023],a general Dabrowski-Sitarz-Zalecki type theorem for odd dimensional manifolds with boundary was proved.In this paper,we give the proof of the another general Dabrowski-Sitarz-Zalecki type theorem for the spectral Einstein functional associated with the Dirac operator on odd dimensional manifolds with boundary.

Nitrogen-doped graphene supported Pd@PdO core- shell clusters for C-C coupling reactions

The introduction of nitrogen significantly decreases the metal particle size and improves the performance of metal-based graphene-supported catalysts. In this work, the density functional theory is used to understand the interaction between nitrogen-doped graphene and Pd@PdO clusters. Experiments show that small size Pd@PdO clusters （1-2 nm） can be grown uniformly on nitrogen-doped graphene sheets by a facile oxidation-reduction method. The nanoscale interaction relationship between nitrogen-doped graphene and Pd@PdO clusters is investigated through X-ray photoelectron spectroscopy （XPS） and X-ray absorption spectra （XAS）. The composite catalysts are applied in Suzuki-Miyaura reactions giving high yields and good structural stability. These results have potential impact in design and optimization of future high performance catalyst materials for cross coupling reactions.

Selenium-functionalized metal-organic frameworks as enzyme mimics

The development of artificial enzyme mimics has been rapidly growing in recent years, and it is attracting increasing attention owing to their remarkable advantages over natural enzymes. Herein, we developed a general and facile method to fabricate efficient glutathione peroxidase （GPx） mimics by grafting selenium-containing molecules （phenylselenylbromide, PhSeBr） to a Zr（W）-based UiO-66-NH2 framework. In the presence of glutathione （GSH） serving as substrate, the fabricated UiO-66-Se catalysts can catalyze the reduction of hydroperoxides. The as-prepared UiO-66-Se systems show good catalytic activity over three cycles. These high-efficiency GPx mimic metal-organic frameworks （MOFs） are endowed with excellent thermal and structural stability, providing a promising avenue for the development of artificial enzyme mimics.

Spatial compartmentalization of metal nanoparticles within metal-organic frameworks for tandem reaction

Fabrication of multifunctional catalysts has always been the pursuit of synthetic chemists due to their efficiency,cost-effectiveness,and environmental friendliness.However,it is difficult to control multi-step reactions in one-pot,especially the spatial compartmentalization of incompatible active sites.Herein,we constructed metal-organic framework(MOF)composites which regulate the location distribution of metal nanoparticles according to the reaction path and coupled with the diffusion of substrates to achieve tandem reaction.The designed UiO-66-Pt-Au catalyst showed good activity and selectivity in hydrosilylation-hydrogenation tandem reaction,because the uniform microporous structures can control the diffusion path of reactants and intermediates,and Pt and Au nanoparticles were arranged in core-shell spatial distribution in UiO-66.By contrast,the low selectivity of catalysts with random deposition and physical mixture demonstrated the significance of artificial control to the spatial compartmentalization of active sites in tandem catalytic reactions,which provides a powerful approach for designing high-performance and multifunctional heterogeneous catalysts.

Chemo-Biocascade Reactions Enabled by Metal-Organic Framework Micro-Nanoreactor

The one-pot combination of biocatalytic and chemocatalytic reactions represents an economically and ecologically attractive concept in the emerging cascade processes for manufacturing.The mutual incompatibility of biocatalysis and chemocatalysis,however,usually causes the deactivation of catalysts,the mismatching of reaction dynamic,and further challenges their integration into concurrent chemo-biocascades.Herein,we have developed a convenient strategy to construct versatile functional metal-organic framework micro-nanoreactors(MOF-MNRs),which can realize not only the encapsulation and protection of biocatalysts but also the controllable transmission of substances and the mutual communication of the incompatible chemo-biosystems.Importantly,the MOFs serving as the shell of MNRs have the capability of enriching the chemocatalysts on the surface and improving the activity of the chemocatalysts to sufficiently match the optimum aqueous reaction system of biocatalysts,which greatly increase the efficiency in the combined concurrent chemo-biocatalysis.Such strategy of constructing MOF-MNRs provides a unique platform for connecting the“two worlds”of chemocatalysis and biocatalysis.

Regulating Electronic Status of Platinum Nanoparticles by Metal-Organic Frameworks for Selective Catalysis

Selective hydrogenation of alkynes to alkenes remains challenging in the field of catalysis due to the ease of over-hydrogenated of alkynes to alkanes.Favorably,the incorporation of metal nanoparticles(MNPs)into metal-organic frameworks(MOFs)provides an opportunity to adjust the surface electronic properties of MNPs for selective hydrogenation of alkynes.Herein,we used differentmetal-O clusters of MOFs to regulate the electronic status of platinum nanoparticles(Pt NPs)toward overhydrogenation,semihydrogenation,and unhydrogenation of phenylacetylene.Specifically,Pt/Fe-O cluster-based MOFs are found to reduce the electronic density on Pt NPs and inhibit the overhydrogenation of styrene,leading to an 80%increase in selectivity toward a semihydrogenation product(styrene).Meanwhile,Cu-O cluster-based MOFs generate high oxidation states of Pt NPs and release Cu^(2+)ions,which worked together to deactivate Pt NPs in the hydrogenation reaction entirely.Thus,our studies illustrate the critical role of metal-O clusters in governing chemical environments within MOFs for the precise control of selective hydrogenation of alkynes,thereby,offering appealing opportunities for designing MNPs/MOFs catalysts to prompt a variety of reactions.