Photocatalytic CO2 reduction with a quantum efficiency exceeding 60%: time-resolved spectroscopic and X-ray studies on Cu(I) photosensitizers in coordinative interaction with Co(II) phthalocyanine catalysts

The utilization of a fully noble-metal-free system for photocatalytic CO2 reduction remains a fundamental challenge, demanding the precise design of photosensitizers and catalysts, as well as the exploitation of their intermolecular interactions to facilitate electron delivery. Herein, we have implemented triple modulations on catalyst, photosensitizer and coordinative interaction between them for high-performance light-driven CO2 reduction. In this study, heteroleptic copper and cobalt phthalocyanine complexes were selected as photosensitizers and catalysts, respectively. An over ten-fold improvement in light-driven reduction of CO2 to CO is achieved for the catalysts with appending electron-withdrawing substituents for optimal CO-desorption ability. In addition, pyridine substituents were implanted at the backbone of the phenanthroline moiety of the Cu(I) photosensitizers and the effect of their axial coordinative interaction with the catalyst was tested. The combined results of 1H NMR titration experiment, steady-state/transient photoluminescence, and transient absorption spectroscopy confirm the coordinative interaction and reductive quenching pathway in photocatalysis corroboratively. It has been found that the catalytic performances of the coordinatively interacted systems are unexpectedly reverse to those with the pyridine-free Cu(I) photosensitizers. Moreover, the latter system enables a very high quantum efficiency up to 63.5% at 425 nm with a high selectivity exceeding 99% for CO2-to-CO conversion. As determined by time-resolved X-ray absorption spectroscopy and DFT calculation, the replacement of phenyl by pyridyl groups in the Cu(I) photosensitizer favors a stronger flattening and larger torsional angle change of the overall excited state geometry upon photoexcitation, which explains the decreased lifetime of the triplet excited state. Our work promotes the systematic multi-pathway optimizations on the catalyst, photosensitizer and their interactions for advanced CO2 photoreduction.

Modulating Electronic Properties of Dinitrosoarene Polymers

We present a comprehensive analysis on how the electronic structure and the optical properties of an organic polymer can be modulated, based on the example of the dinitrosobenzene polymer (1). Using a combination of computational and experimental tools, we explore the effects of solid-state packing, backbone torsion, surface adsorption, the conjugation in the aromatic core, and substituents. The band gap (Eg) and optical spectrum of 1 are calculated using both GW-BSE with zero-gap renormalization (ZGR) and hybrid TD-DFT, with the former method predicting a value (2.41 eV) in excellent agreement with our diffuse reflectance spectroscopy measurements (2.39 eV). Using GW-BSE-ZGR, changes occurring upon solidstate packing are separated into a contribution arising from (i) the change in the torsional angle and (ii) the change in the screened Coulombic interaction, which strongly effects the exciton binding energies. Comprehensive hybrid TD-DFT calculations find that the effects of substituents on Eg and on transport properties can mostly be explained through changes in the torsional angle, and predict a linear dependence between it and Eg. Extending the conjugation in the aromatic core is found to enhance transport properties and narrow Eg, identifying future synthetic targets. Atomic force microscopy and spectroscopic ellipsometry are used to study 1 adsorbed to a (111) gold surface (1@Au), with the latter method showing a significant narrowing of the band gap to 0.68 eV, in good agreement with TD-DFT predictions.

Modeling and Dynamics Analysis of a Dual-Mass Flywheel with the Conformal Contact Action of Friction Damping Ring and Pressure Plate

To study the nonlinear dynamic characteristics of the dual-mass flywheel (DMF) under the conformal contact action between the friction damping ring and primary flywheel pressure plate, the contact action model is established and analyzed based on Winkler model. Through analysis and calculation, the contact deformation, contact pressure at different contact positions, and equivalent torsional contact stiffness are obtained. The nonlinear dynamic analysis model of three-degree-of-freedom (3DOF) which takes the conformal contact into account and two-degree-of-freedom (2DOF) without considering conformal contact is established. The approximate analytical solution of the nonlinear frequency characteristics of the system at steady state is derived. By comparing with the results obtained from numerical method, the theoretical analysis process is proved to be valid. And it is found that the overall amplitude and angular displacement transmissibility of the 3DOF model are smaller than the 2DOF model, especially at resonance frequency. The effects of the friction damping ring moment inertia, stiffness of DMF, and axial friction torque on the frequency characteristics of system and angular displacement transmissibility are analyzed. The forced vibration response analysis of the 3DOF model is conducted, through which the torsional angle variations of the primary flywheel, friction damping ring, and secondary flywheel with time are obtained. The results show that the amplitude of the secondary flywheel is much smaller than that of the primary flywheel, indicating that the DMF has prominent damping performance.

Design Of Horizontal Type Of Wind Turbine On A Highrise Building

In making a horizontal type wind turbine, of course, it is necessary to analyze it in depth, one of which is by predicting the production of wind energy produced by the wind turbine to estimate the wind power in the wind turbine which will later be applied. Wind energy sources that are commonly used are located in rural areas, fields and even there is such a large amount of energy that it is sometimes difficult to reach the power grid and other large areas including the roofs of high-rise buildings. There are many analytical models in wind energy estimation, one of which is often done by many researchers, namely by using the Weibull distribution method. From the measurement results that as many as 1516.37 kWh with a 1 kW wind turbine with a radius of 1 meter (capacity factor 30.09%). Modeling wind turbine blades with NACA 4412 using Qblade software to determine the torsional angle of the blade to be applied so that it is obtained that the torsion angle from the base and The tip of the blade has a tilt angle of 19.05◦ to 6.96° with a maximum Cp of 0.5 this is a pretty good value in designing wind turbine blades.

Sequence Recognition by a Pseudorotational Cycle of Sugar Puckers: A Base Pair Switching Model via N-E Sugar Pucker Conversion for Homologous Recombination

A triplex DNA model bound to a helical filament of homologous recombination protein, such as Escherichia coli RecA, is presented. This model suggests that a function of the nucleoprotein filament could be at least partly attributed to the lowering of transition energy of duplex DNA structure having the E-type sugar puckers. Key events during homologous recombination such as sequence recognition, base pair switching and elongation/contraction of the helical pitch may correlate with the pseudo-rotation angle of sugar puckers along the N-, E-, S- and W-types. A conformational change of sugar puckers during the reaction is resolved into two motions by introducing a pair of parameters, μ1 and ν3, which defines a swing orientation of bases and a torsional angle of phosphate backbones, respectively.

Theoretical Study of N-Heterocyclic-Carbene–ZnX2 (X = H, Me, Et) Complexes

This article discusses the properties of as many as 30 carbene–ZnX2 (X = H, Me, Et) complexes featuring a zinc bond C⋯Zn. The group of carbenes is represented by imidazol-2-ylidene and its nine derivatives (labeled as IR), in which both hydrogen atoms of N-H bonds have been substituted by R groups with various spatial hindrances, from the smallest Me, iPr, tBu through Ph, Tol, and Xyl to the bulkiest Mes, Dipp, and Ad. The main goal is to study the relationship between type and size of R and X and both the strength of C⋯Zn and the torsional angle of the ZnX2 plane with respect to the plane of the imidazol-2-ylidene ring. Despite the considerable diversity of R and X, the range of dC⋯Zn is quite narrow: 2.12–2.20 Å. On the contrary, D0 is characterized by a fairly wide range of 18.5–27.4 kcal/mol. For the smallest carbenes, the ZnX2 molecule is either in the plane of the carbene or is only slightly twisted with respect to it. The twist angle becomes larger and more varied with the bulkier R. However, the value of this angle is not easy to predict because it results not only from the presence of steric effects but also from the possible presence of various interatomic interactions, such as dihydrogen bonds, tetrel bonds, agostic bonds, and hydrogen bonds. It has been shown that at least some of these interactions may have a non-negligible influence on the structure of the IR–ZnX2 complex. This fact should be taken into account in addition to the commonly discussed R⋯X steric repulsion.

The Effects of Modified Graded Recession, Anteriorization and Myectomy of Inferior Oblique Muscles on Superior Oblique Muscle Palsy

Background: The aim was to investigate the effect of inferior oblique (IO) operation (IO myectomy or graded recession and anteriorization) for unilateral and bilateral superior oblique muscle palsy (SOP); Methods: A total of 167 eyes undergoing IO surgery by a single surgeon between 2008 and 2015 were retrospectively reviewed. The method for treating symmetric bilateral SOP was bilateral IO myectomy (n = 102) and the method for treating unilateral SOP or non-symmetric bilateral SOP was IO-graded recession and anteriorization (n = 65). Associated clinical results and other factors were analyzed; Results: Head tilt, vertical deviation, IO overaction, SO underaction degree and ocular torsion angle were all clearly changed, but there was no statistically significance between these two procedures. Mean preoperative torsional angle was 15.3 ± 6.4 degree, which decreased to 5.3 ± 2.7 degree after surgery. Preoperative torsional angle, IOOA and SOUA degree were all significantly affected in postoperative torsional angle (p = 0.025, 0.003 and 0.038). Horizontal rectus muscle and IO muscle operation did not interfere with each other’s results (p = 0.98); Conclusions: Symmetric bilateral SOP could be treated with bilateral IO myectomy and IO-graded recession and anteriorization should be reserved for unilateral SOP or non-symmetric bilateral SOP.

Design and Performance Study of Clutch Disc Assembly of Wide-Angle, Large-Hysteresis, Multistage Damper

The clutch is an important component of the vehicle driveline system. One of its major functions is to attenuate or eliminate the torsional vibration and noise of the driveline system caused by the engine. Based on experiments of vibration damping under different vehicle conditions, the structure and functional principle of a clutch-driven disc assembly for a wide-angle, large-hysteresis, multistage damper is investigated in this study using an innovative combined approach. Furthermore, a systematic integration of key technologies, including wide-angle low-stiffness damping technology, large-hysteresis clutch technology, a novel split pre-damping structure technology, damping structure technology for component cushioning, and multistage damping structure technology, is proposed. The results show that the total torsional angle of the wide-angle large-hysteresis, multistage damper is more than twice that of the traditional clutch damper. The multistage damping design allows a better consideration of various damping requirements under different vehicle conditions, which can effectively address problems of severe idle vibrations and torsional resonance that occur under idled and accelerated conditions. Meanwhile, the use of a large-hysteresis structure and wear-resistant materials not only improves the vibration damping performance, but also prolongs the product service life, consequently resulting in multi-faceted optimization and innovative products.

Study on the load-sharing characteristics of face-gear four-branching split-torque transmission system

In order to solve the load-sharing characteristics of face-gear four-branching split-torque transmission system (FGFBSTTS), the static load-sharing mechanical analysis model was established. In the model, the deformation coordination conditions of torsional angle and torque balance condition were considered. By using Loaded Tooth Contact Analysis (LTCA) technology of face gear and herringbone gear, the time-varying meshing stiffness was calculated. The influences of manufacturing errors, installation errors, I-stage pinion floating, II-stage pinion spline clearance floating, and radial limit ring clearance floating on the load-sharing characteristics are analyzed. The results show that the LTCA technology is more accurate to reflect the load-sharing characteristics of each meshing position. When the I-stage pinion and the II-stage pinion floated at the same time, the best load-sharing characteristics can be obtained. The load-sharing characteristics affected by manufacturing errors showed obvious periodic change. The radial limit ring plays a better auxiliary role in load-sharing characteristics. The theoretical results were compared with the experiments to verify the correctness of the theoretical analysis. The research results can provide a theoretical basis for the optimal design of the load-sharing structure, error control, and assembly of the face gear four branch transmission system.

Crystal structure of the sesquihydrate of dehydroepiandrosterone propan-2-ylidene hydrazone: Participation of the hydrazonyl nitrogen atoms as acceptors in the elaborate hydrogen bond scheme

The crystal structure of the sesquihydrate of dehydroepiandrosterone propan-2-ylidene hydrazone, [(7)2·(H2O)3], isolated from a solution of dehydroepiandrosterone propan-2-ylidene hydrazone, (7), in moist ethanol at room temperature, has been determined from data collected at 100 K. The sesquihydrate recrystallizes in the orthorhombic space group, P212121 with Z = 8. The asymmetric unit of [(7)2·(H2O)3] consists of two independent molecules of the steroid, Mol A and Mol B, and three moles of water. The six membered saturated rings, A and C, in both molecules have ideal or near ideal chair shapes, the unsaturated rings, B, have the expected half-chair shapes, while the five-membered rings, D, have envelope shapes with flaps at C114 and C214 for Mol A and Mol B, respectively. Differences in the conformations of the two molecules reside essentially completely within the hydrazonyl fragments with significantly different torsional angles, C117-N120-N121-C122 (in Mol A) and C217-N220-N221-C222 (in Mol B), of 149.19(14) and -93.08(17)°, respectively. The difference in this torsional angle is reflected in the hydrogen bonds involving the nitrogen atoms in the hydrazonyl units: it is of interest that the hydrazonyl nitrogen atoms partake as acceptors in hydrogen bonding with water molecules. The only intermolecular interactions in these molecules are hydrogen bonds -all classical O-H-O and OH···N hydrogen bonds with just one exception, a C-H···O(water) hydrogen bond. Of interest, there are no direct steroid-steroid links: molecules are linked solely by hydrogen bonds involving the hydrate molecules. All three hydrate molecules take part in the indirect linking of the steroid molecules, but each has its own set of contacts.