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The 1-azole-8-aryl-BODIPY and 1,9-diazole-8-aryl-BODIPY derivatives were synthesized by the reaction of BODIPY with some azoles (1H-1,2,3-triazole, 1,2,4-triazole, 1H-tetrazole, pyrazole, benzopyrazole) in the presence of Selectfluor in moderate yield. The reaction proceeds regioselectively in 1(9)-position of the BODIPY ring, which was confirmed by single crystal X-ray analysis. [ABSTRACT FROM AUTHOR]

Abstract: To gain ideal conjugated polymers with a low band-gap (E g) and a deep HOMO (highest occupied molecular orbital) energy level for photovoltaic application, both strong and weak electron withdrawing units were introduced into polymer backbone. A series of –(D–A1–D–A2) n – type diketopyrrolopyrrole (DPP) containing polymers P1–P7 were designed and synthesized. The resulting copolymers exhibited both low E g of 1.27–1.48 eV and deep HOMO energy levels of −5.25to −5.44 eV. Preliminary photovoltaic properties of the copolymers blended with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) were investigated. All photovoltaic devices featured high open circuit voltages (V oc, 0.72–0.91 V). Among the seven copolymers, P5 exhibited the best performance with a V oc of 0.80 V, a short circuit current density (I sc) of 3.48 mA/cm2, a fill factor (FF) of 43.2%, and a power conversion efficiency (PCE) of 1.33%. [Copyright &y& Elsevier]

Abstract: A series of conjugated polymers were designed and synthesized via the alternating copolymerization of the electron-donating monomer 2,7-carbazole and electron-accepting monomers of naphthalene diimide (NDI), dithienyl-naphthalene diimide (DTNDI), perylene diimide (PDI) and dithienyl-perylene diimide (DTPDI), respectively. The obtained four copolymers showed good thermal stability as well as broad absorptions in visible region and narrow optical band gaps (1.86–1.59eV). Through cyclic voltammetry (CV) measuremnts, it was found that all copolymers were n-type semiconductive materials. The copolymers'' photovoltaic properties were evaluated when the blends of poly(3-hexyl thiophene) (P3HT) and copolymers were used as the active layers of polymer solar cells (PSCs): among four copolymers, the copolymer alternating 2,7-carbazole and DTPDI units (PCDTPDI) exhibited the best photovoltaic performance with an open-circuit voltage (V oc) of 0.48V, a short circuit current density (J sc ) of 3.40mA/cm2, fill factor (FF) of 0.42, and a power conversion efficiency (PCE) of 0.68%. [Copyright &y& Elsevier]

Abstract: The lower the highest occupied molecular orbital (HOMO) energy level of the conjugated polymer is, the higher the open-circuit voltage (VOC ) of the obtained polymer solar cell (PSC) is. To achieve this goal, a new conjugated polymer (PDTPTPD) alternating dithienopyrrole (DTP) and thienopyrroledione (TPD) units was designed and synthesized by Stille coupling reaction. Through UV–vis absorption and cyclic voltammetry (CV) measurements, it was found that the resulting copolymer exhibited both a low optical band gap of 1.62 eV and a low HOMO energy level of −5.09 eV owing to the electronegativity of TPD moiety. Preliminary photovoltaic study disclosed that the PSC based on PDTPTPD:PCBM ([6,6]-phenyl-C61 butyric acid methyl ester) blend showed a power conversion efficiency (PCE) of 1.9%, with a VOC of 0.70 V, and a short circuit current (ISC ) of 6.97 mA/cm2, suggesting that PDTPTPD is a promising photovoltaic polymer. [Copyright &y& Elsevier]

Micro-defects on the surface of turbine blades can lead to aviation accidents, thus it is important to thoroughly detect. To realize micro-defect detection, we propose a small object detection model from three aspects: multiscale representation, contextual information and region proposal. The proposed Spatial Feature Pyramid Network (SFPN) achieves feature fusion by integrating cross-scale information and representing the fusion results in a multiscale method. To incorporate contextual information, we introduce a Spatial Attention Residual (SAR) module into SFPN for acquiring global spatial information. Furthermore, to capture global channel information and additional contextual information, we design a Selective Multiple Kernel Networks (SMK) module. For region proposal, inspired by the effective screening strategy employed by Varifocal Network (VFNet), we further optimize our model's screening strategy for positive sample region proposals. Based on VFNet, a Micro-defect Varifocal Network (MVFNet) is designed by integrating SFPN and SMK. MVFNet is validated on the NEU-DET dataset with AP reaching 45.8%, exceeding VFNet by 7.7%. The MVFNet achieves an AP of 73.5% in our self-made Turbine Blade Defect (TBD) dataset, while maintaining a remarkable processing speed of 12 images per second at a resolution of 2448 × 2048 pixels. Furthermore, the detection model has been successfully implemented in a real-time automatic turbine blade detection system. [ABSTRACT FROM AUTHOR]

We developed a film-forming processing method for morphology control and organic solar cells (OSCs) optimization. In this protocol, the processing solvent inside a wet active layer is removed by dripping a soaking solvent that is selectively soluble for the processing solvents onto the wet active layer film. By this method, OSCs based on diketopyrrolopyrrole containing copolymers: [6,6]-phenyl-C61-butyric acid methyl ester blend were fabricated. Devices processed by this treatment show a significantly increased efficiency by a factor of 3 compared to devices fabricated by the traditional spin-coating method (from 1.03% to 3.2%), which is mainly attributed to morphology improvements. [ABSTRACT FROM AUTHOR]

In this article, a simple and common electron-withdrawing moiety, carbonyl group, is applied in the molecular design of conjugated polymers for high-performance polymer solar cells (PSCs). Two series of donor-acceptor (D-A) copolymers are synthesized through alternating copolymerization of the electron-donating (D) benzodithiophene and dithienopyrrole with various electron-accepting (A) units containing carbonyl groups. The absorption range and the band gap of copolymers can be tuned by changing the molecular structure of A unit and the number of carbonyl groups. Moreover, by introducing the carbonyl group, the highest occupied molecular orbital energy level of the copolymer is lowered efficiently, leading to the improvement of the open-circuit voltage ( V) of PSCs. The best photovoltaic performance is obtained while poly(benzodithiophene- alt-thiophene-3-carboxylate) is functioned as the electron donor and [6,6]-phenyl-C-butyric acid methyl ester as electron acceptor in a bulk heterojunction solar cell with a power conversion efficiency of 4.13%, a V of 0.80 V, a short-circuit current of 8.19 mA/cm, and a fill factor of 63.2%. [ABSTRACT FROM AUTHOR]

A simple epoxidation of E-2-(arylmethylidene)-2,3-dihydro-1H-pyrrolizin-1-ones was accomplished using cyclohexylidenebishydroperoxide as the oxygen source. A number of 3-arylspiro[oxirane-2,2'-pyrrolizin]-1'(3'H)-ones were obtained in moderate to good yields. [ABSTRACT FROM AUTHOR]

An abstract of the article "Synthesis of Novel Spiro[oxirane-pyrrolizin] Derivatives by Epoxidation of α,β-Unsaturated Pyrrolizinone with Cyclohexylidenebishydroperoxide" by L. Yang and colleagues is presented.

In this paper, we introduce a class of predator-prey system with general functional response, whose harvesting policy is modeled by a discontinuous function. Based on the differential inclusions theory, topological degree theory in set-valued analysis and generalized Lyapunov approach, we analyze the existence, uniqueness and global asymptotic stability of positive periodic solution. In particular, a series of useful criteria on existence, uniqueness and global asymptotic stability of the positive equilibrium point are established for the autonomous system corresponding to the non-autonomous biological and mathematical model with a discontinuous right-hand side. Moreover, some new sufficient conditions are provided to guarantee the global convergence in measure of harvesting solution and convergence in finite time of any positive solution for the autonomous discontinuous biological system. The obtained results, which improve and generalize previous works on dynamical behavior in the literature, are of interest for understanding and designing biological system with not only continuous or even Lipschitz continuous but also discontinuous harvesting function. Finally, we give three examples with numerical simulations to show the applicability and effectiveness of our main results. [ABSTRACT FROM AUTHOR]

The interaction between novel spiro[cyclopropane-pyrrolizin] (NSCP) and bovine serum albumin (BSA) was analyzed by fluorescence and ultraviolet–visible (UV–Vis) spectroscopy at 298 K, 304 K and 310 K under simulative physiological conditions. The results showed that NSCP can effectively quench the intrinsic fluorescence of BSA via static quenching. The binding constants, binding sites of NSCP with BSA were calculated. Hydrogen binds and van der Waals force played a major role in stabilizing the complex and the binding reaction were spontaneous. According to the Förster non-radiation energy transfer theory, the average binding distances between NSCP and BSA were obtained. What is more, the synchronous fluorescence spectra indicated that the conformation of BSA has been changed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Three DPP derivatives with different end-groups were designed and synthesized. [•] Three DPP derivatives exhibit similar energy structures but different photovoltaic properties. [•] End-groups influence photovoltaic properties of three molecules through the inducing of different morphologies. [ABSTRACT FROM AUTHOR]