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Satellite laser communication is a promising technology for the next-generation communication system. Its communication performance is subject to the APT beam-pointing accuracy. One of the most important problems is reducing the coaxiality error before the APT starts working. However, the coaxiality error is difficult to correct effectively owing to the lack of empirical guidance based on qualitative analysis. We study the inducement that will generate coaxiality errors. The mathematical model of the influence of the CCR dihedral angle error and planeness error on the spot centroid measurement are built, and an analysis is performed. The model of the beam-pointing error induced by the APT element's assembly error is built, and the pointing error change rule is explored. Furthermore, the coaxiality performance simulation is performed in the presence of a CCR geometrical error while considering the assembly error. The results show that the coaxiality error has a nonlinear characteristic. The CCR planeness error has a greater influence on coaxiality deviation than that of dihedral angle error under certain conditions. This research is relevant to the design and test work of the APT system. [ABSTRACT FROM AUTHOR]

Various force fields and water model potentials influence significantly RNA conformations. The polyanionic nature of RNA attracts the water molecules and the counter ions which in turn affects their stability. The interfacial water's structural and dynamic aspects affect the RNA's base-pair opening and denaturation by breaking or making inter/intra-hydrogen bonds. Herein, we employed an MD simulations study using SPC/E and modified TIP3P water models in combination with different force fields CHARMM and AMBER to find their influence on the hydration shell of the SARS-CoV-2 RNA genome at different temperatures. AMBER-mTIP3P model was found to give more dynamic and transient conformations for RNA. The lower dielectric constant of the SPC/E model helps in the formation of the ion-contact pair near the negatively charged phosphate group (Na+-PO4−) leading to strong RNA-ion interaction and strong hydration shells having higher hydrogen bond lifetime. The Na+ ion survival probability at the interface was found to be more in the SPC/E model. At lower temperatures, the water molecules inside these hydration shells were found to be inhomogeneous, with lower void space, higher-coordinated, and non-tetrahedral. The higher dielectric constant of the mTIP3P model screened out the attraction between the ion pairs leading to a more homogenous solvation shell having a lesser hydrogen bond lifetime and more diffusive water. The distribution of the ions near the RNA structure is confirmed by metadynamics simulations. Both water models were found to disrupt the base pair orientation due to the formation of water bridges between the O2ʹ group of RNA and the water molecules.

Abstract Orientations of active antithetic faults can provide useful constraints on in situ strength of the seismogenic crust. We use LINSCAN, a new unsupervised learning algorithm for identifying quasi‐linear clusters of earthquakes, to map small‐scale strike‐slip faults in the Anza‐Borrego shear zone, Southern California. We identify 332 right‐ and left‐lateral faults having lengths between 0.1 and 3 km. The dihedral angles between all possible pairs of conjugate faults are nearly normally distributed around 70°, with a standard deviation of ∼30°. The observed dihedral angles are larger than those expected assuming optimal fault orientations and the coefficient of friction of 0.6–0.8, but similar to the distribution previously reported for the Ridgecrest area in the Eastern California Shear Zone. We show that the observed fault orientations can be explained by fault rotation away from the principal shortening axis due to a cumulated tectonic strain.

This study reports unique luminescent properties of pyrene‐substituted nido‐carborate anion (PYnCA) with two counter cations, tetrabutylammonium (NBu4+) and tetraphenylphosphonium (PPh4+). It is revealed that PYnCA shows twisted intramolecular charge transfer (TICT) emission by the change of the dihedral angle between pyrene and the CcageCcage bond in the carborane unit in the excited state. Although the structure of nCA is almost same as that of ortho‐carborane (oC), the photophysical processes of both pyrene‐substituted compounds are completely different. The study also succeeds in modulating the luminescence species by counter cations in both solution and solid states. To the best of the current knowledge, this is the first report that anion‐based luminescent materials can show the different luminescent species not only in solution but also in the mechanochromic behaviors depending on the type of counter cations. This fundamental research on nCA demonstrates anion‐based emitters as a new platform for stimuli‐responsive materials. [ABSTRACT FROM AUTHOR]

The third‐order nonlinear optical properties of NOC6F‐1 and NOC6F‐2, two mutually isomeric noncovalently fused‐ring A‐π‐D‐π‐A electron acceptor molecules, are investigated using the Z‐scan technique in both film and solution forms. NOC6F‐1 possesses a planar structure, whereas NOC6F‐2 has a large dihedral angle between its central and neighboring conjugated units. NOC6F‐2 exhibits clearly superior reverse saturation absorption properties compared to NOC6F‐1, both in poly(methyl methacrylate) (PMMA) films and in polar solvents such as chloroform and chlorobenzene. In particular, NOC6F‐2/PMMA exhibits a nonlinear absorption coefficient (βeff) of 7.2 × 10−10 m W−1, which is almost an order of magnitude higher than that of NOC6F‐1/PMMA (8.8 × 10−11 m W−1). Density functional theory calculations reveal that NOC6F‐2 has a large dipole moment and second hyperpolarizability owing to its large dihedral angle, which decisively affects its non‐linear optical behavior. In addition to conjugation and charge transfer, the dipole moment is another important factor that enhances the nonlinear optical properties of organic molecules. This study provides useful guidance for the future design of high‐performance organic non‐linear optical materials. [ABSTRACT FROM AUTHOR]

Many aggregation‐induced emission (AIE) molecules based on tetraphenylethylene (TPE) structure have been synthesized, but a clear understanding of the photophysical difference between different isomeric pyridyl‐based tetraphenylethylene molecules remains elusive. Herein, we designed a series of isomeric tetraphenylethylene‐pyridines (o‐Py‐TPE, m‐Py‐TPE, p‐Py‐TPE) to investigate the influence of the position of N atoms in the pyridine subunit on the photophysical property of the whole molecule by detailed DFT calculations and single‐crystal structures analysis. All compounds show typical AIE properties, and notably, the meta pyridyl isomer (m‐Py‐TPE) shows the highest solid photoluminescence quantum yield (PLQY) up to 64.56 %. Further investigation and DFT calculations indicate that the center C=C bond dihedral angles of the TPE subunit in the solid state of these compounds, which are affected by C−H⋅⋅⋅π interaction, play a vital role in their emission and PLQY properties. This work provides underlying principles for the design of pyridyl‐based TPE molecules with high photoluminescent performance in the future. [ABSTRACT FROM AUTHOR]

Stimuli-responsive luminescence plays a crucial role in the development of mechanoluminescent materials. Here, we designed and synthesized four o-carborane-based aggregation-induced emission molecules, two of which, CB-Ph-P and CB-Ph-PAn, exhibited multiple solid-state fluorescence emissions. Upon mechanical stimulation, the recrystallization solid of CB-Ph-P caused a bathochromic shift in its fluorescence emission from 423 nm to 608 nm. Similarly, CB-Ph-PAn exhibits a transition in the fluorescence emission wavelength from 393 nm to 623 nm when in the solid state. In order to gain insight into the mechanism behind their luminescence behavior, we performed analyses including powder X-ray diffraction, photophysical properties, thermal properties, and single-crystal structure analysis. It is deemed that the polymorphism may be related to different weak interactions, packing modes and torsion angles. [ABSTRACT FROM AUTHOR]

2-Bromo-3-nitroacetophenone (I) and 2-Bromo-4-nitroacetophenone (II), which are structural isomers of each other, were characterized using proton/carbon NMR, FT-IR, and density functional methods. The effects of the substituents on the molecular geometry parameters were investigated by comparing the optimized molecular structures obtained by computational methods with root mean square error calculations. The potential energy surface scan of the torsion angle between the bromoacetone group and the ring revealed that the lowest energy conformation is at 110°. The molecules' chemical reactivity and kinetic stability in different solvents were studied using frontier molecular orbital analyses. NMR core assignments and IR vibration assignments revealed similarities between the isomers. At the computational level that we determined to be sufficient in accuracy and precision for molecular geometry and spectrum calculations, it was found that the average polarizability of the compounds are approximately five times, and the total high-level polarizability are approximately four times greater than the reference compound when their nonlinear optical properties are theoretically calculated. [ABSTRACT FROM AUTHOR]

Various angle characteristics are used (e.g. in finite element methods or computer graphics) when evaluating the quality of computational meshes which may consist, in the three-dimensional case, of tetrahedra, prisms, hexahedra and pyramids. Thus, it is of interest to derive (preferably tight) bounds for dihedral angle sums, i.e. sums of angles between faces, of such mesh elements. For tetrahedra this task was solved by Gaddum in 1952. For pyramids, this was resolved by Korotov, Lund and Vatne in 2022. In this paper, we compute tight bounds for the remaining two cases, hexahedra and prisms. [ABSTRACT FROM AUTHOR]

In this work, twelve phenolic compounds were isolated and identified from Inonotus Obliquus using preparative high-performance liquid chromatography. The effect of the phenolic compounds on catalase was analyzed by ammonium molyb⁃ date colour development. The results showed that protocatechuic aldehyde, phelligridin E, and phelligridin I showed the ability to enhance catalase activity, especially Phelligridin E. treatments with phelligridin E at final concentrations of 0.5, 1.0, 2.0, 3.0, 4.0, and 5.0 μmol/L increased catalase activity by 41.90%, 44.68%, 52.66%, 58.10%, 62.78%, and 68.10%, respectively. The mechanism of catalase activation by phelligridin E was analyzed by molecular docking and molecular dynamics simulations. The results of analysis showed that Phelligridin E formed strong hydrophobic forces with ASN369, HIS372, and ILE373 of cata⁃ lase, and formed hydrogen bonds with ASP25, ASN369, HIS372, PRO391, and CYS393 of catalase. The application of gmx_MMPBSA for free energy decomposition showed that GLU67, ILE373, and PRO391 of catalase contributed more to the binding of phelligridin E to catalase. Among them, ILE373 formed a hydrophobic force with phelligridin E at a distance of 3.63 Å and PRO391 formed a hydrogen bond with phelligridin E at a distance of 2.54 Å. GLU67 of catalase did not form an interaction with phelligridin E in the distance range of 4 Å, but GLU67 was spatially located near ASP25. The hydrophobic force and hydro⁃ gen bond between phelligridin E and catalase caused dihedral angle reversal in VAL41, CYS393, ASP396, GLY399, and GLY400 of catalase. The dihedral twisting of amino acid residues at these positions drove ASN33-GLN53 to form a B-Sheet, CYS393-ASN403 to form a 5-Helix, and ASN433-ASP438 to form a 3-Helix. The transformation of the catalase secondary structure increased the distance between the upper and lower surroundings of the active center of catalase, increasing the access of substrates to the active center and enhancing the ability of catalase to eliminate hydrogen peroxide. [ABSTRACT FROM AUTHOR]

X‐ray diffraction studies reveal that pyrazine‐2‐thiol undergoes condensation to 2,2′‐dithiobispyrazine [systematic name: 2‐(pyrazin‐2‐yldisulfanyl)pyrazine], C8H6N4S2 (I), under aerial conditions. In the molecule of I, the pyrazine rings are arranged in an almost perpendicular manner, with an absolute value of the C—S—S—C torsion angle of −91.45 (6)°. A search in the Cambridge Structural Database confirmed that such a conformation is typical for disulfide compounds. Three different rotamers of disulfide I were studied using quantum theoretical studies. The rotamer of lowest energy was observed in the crystalline state in the structure stabilized by hydrogen‐bond, chalcogen‐bond and stacking interactions. Further quantum chemical computations confirm that 2,2′‐dithiobispyrazine can react according to the SN2 mechanism. [ABSTRACT FROM AUTHOR]

Methyl 3-O-α-d-glucopyranosyl 2-acetamido-2-deoxy-α-d-galactopyranoside as a monohydrate, C15H27NO11·H2O, crystallizes in space group P212121, with four molecules in the unit cell. It constitutes the methyl glycoside of the carbohydrate part of the teichoic acid type polysaccharide from Micrococcus sp. A1, in which the disaccharides are joined through phosphodiester linkages. The conformation of the disaccharide is described by the glycosidic torsion angles ϕ = − 31° and ψ = + 1°, and the hydroxymethyl groups of the constituent monosaccharides are present in the gg and gt conformations for the sugar residues having the gluco- and galacto-configuration, respectively. For the N-acetyl group at C2 of the galactosamine residue the torsion angle τH = 147°, i.e., the amide proton has an antiperiplanar relationship to H2 of the sugar ring. The structure shows extensive hydrogen bonding along the a-direction, including the water molecule, and forms sheets with hydrophilic interactions within the sheets as a result of hydrogen bonding between disaccharides as well as hydrophobic interactions between the sheets, in particular, amongst methyl groups of the N-acetyl group of the α-d-GalpNAc residue in the disaccharides. The structure of the title disaccharide as a monohydrate, C15H27NO11·H2O, which shows extensive hydrogen bonding as well as hydrophobic interactions, was determined from minute crystals using synchrotron radiation and verified by solid state DFT calculations using plane waves. [ABSTRACT FROM AUTHOR]

To solve the problem of the steel longitudinal beam being unable to match precise installation of the steel main beam due to torsional deformation during the steel installation process of a composite twin-box girder cable-stayed bridge, a torsion correction method through the multipoint jacking adjustment of transverse steel beams is proposed. Based on the constrained torsion calculation theory for closed thin-walled members, a constrained torsion differential equation for steel longitudinal beams and its general solution were established. Then, the torsion angle and the jacking force on each steel beam at zero torsion angles were obtained. In addition, a local refined model by the finite element software Abaqus was established, simulating the jacking process with the transverse steel beams as a lever arm. The accuracy of the theoretical and numerical analysis was verified by the measured results on site. Results show that the torsion angle of the steel longitudinal beam could be adjusted through multipoint jacking of the steel crossbeam, the installation error caused by the torsion is effectively eliminated, and the efficiency and accuracy of the composite twin-box girder cable-stayed bridge are improved. [ABSTRACT FROM AUTHOR]

This study aimed to determine solid/liquid interfacial energies of an Al–2.5at pct Cu alloy at 568 °C under different intensities of static magnetic field (SMF) using the dihedral angle method. The results demonstrate an increase of interfacial energies in Al–Cu alloy with increasing SMF intensities between 0 and 12 T. Experimental results reveal a threefold variation of the interfacial energies. The theoretical prediction of the interfacial energies under SMF is consistent with the experimental results. [ABSTRACT FROM AUTHOR]

AgW materials exhibit excellent properties and are widely used as contact materials in low- and medium-voltage switches. In this study, a pre-sintering and infiltration method was employed to pre-sinter W powder with Cu, Ni, and (Cu+Ni) additions in the low temperature range of 950–1050 °C. The low-temperature sintering behaviours of W skeletons with different additives were investigated. Subsequently, AgW (70 wt%), AgW (75 wt%), AgW (80 wt%), and AgW (85 wt%) materials were prepared through infiltration at 1050 °C. The microstructure morphology and physical properties of high-W contact materials were investigated using a metallographic microscope and scanning electron microscope. The mechanism of low-temperature sintering–infiltration of high-W contact materials was elucidated. The results indicate that pure W and 1% Cu-added W skeletons experience minimal linear shrinkage within the temperature range of 950–1050 °C. The linear shrinkage curves of W skeletons with different additives coincided under the conditions of 950–1000 °C/90 min. At 1050 °C, after sintering for 150 min, the particle boundaries in the W skeleton were fully spheroidised, with a dihedral angle of 120°. At 1050 °C and after 150 min of infiltration, cross-sectional micrographs of the AgW material revealed the presence of irregular Ni layers, where Ni spatially enveloped/encapsulated Ag. With an increase in the W content, the electrical conductivity and relative density of AgW (70–85) materials decreased, whereas the hardness of the materials increased. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Beijing University of Technology is the property of Journal of Beijing University of Technology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Recent simulation studies have revealed a wealth of distinct crystal polymorphs encountered in the self-organization of polymer systems driven by entropy or free energy. The present analysis, based on the concept of self-avoiding random walks (SAWs) on crystal lattices, is useful to calculate upper bounds for the entropy difference of the crystals that are formed during polymer crystallization and thus to predict the thermodynamic stability of distinct polymorphs. Here, we compare two pairs of crystals sharing the same coordination number, ncoord: hexagonal close-packed (HCP) and face centered cubic (FCC), both having ncoord = 12 and the same packing density, and the less dense simple hexagonal (HEX) and body centered cubic (BCC) lattices, with ncoord = 8. In both cases, once a critical number of steps is reached, one of the crystals shows a higher number of SAWs compatible with its geometry. We explain the observed trends in terms of the bending and torsion angles as imposed by the geometric constraints of the crystal lattice. [ABSTRACT FROM AUTHOR]

An anthracene-derived luminogen, A-4OH, obtained by reacting anthracene-9-aldehyde with 4-hydroxy benzoic acid hydrazide, produced two polymorphic phases and two solvates, each of which could be distinguished by the solid state emission. The luminogen A-4OH was constructed by attaching the anthracene motif to a 4-hydroxyphenyl group by means of the hydrazide group, which was expected to determine the molecular geometry in terms of the relative orientation of the anthracene motif and 4-hydroxyphenyl group. We isolated a green emissive phase, A-4OH-G, wherein the molecules adopted twisted conformations in the lattice, with the anthracene groups oriented 'cisoid' with respect to the 4-hydroxyphenyl group (C–C＝N–N torsion angles of 2.4° and 2.7°). Two symmetry-independent molecules were observed in the lattice of A-4OH-G, wherein the anthracene motifs were held in place by end-to-face interactions (angles between the aromatic planes ∼70 to 72°) and slipped face-to-face interactions. Subsequently, we isolated the weakly emissive A-4OH-O form, as a solvate from N,N-dimethylformamide (DMF), while the non-emissive A-4OH-NE form was obtained from methanol. Crystal analysis of the A-4OH-O and A-4OH-NE forms revealed distinct aromatic–π interactions between the anthracene motifs with face-to-face overlap. Furthermore, thermal stimulation of the A-4OH-NE form triggered the release of the solvated DMF molecules from the lattice affording a yellow emissive phase, A-4OH-Y, which could be characterised using powder X-ray diffraction and thermal methods. [ABSTRACT FROM AUTHOR]

In order to effectively improve the impact resistance performance of the roadway anti-impact hydraulic support and reduce the loss caused by rock burst to a certain extent, a torsion plate energy-absorbing member was designed for using with the hydraulic column. By using theoretical analysis and numerical simulation methods and combining them with the parameters of the energy-absorbing characteristics evaluation index, single-factor tests were designed. Under the premise of constant impact velocity, the influence law of torsion angle, plate thickness, and fillet radius of the pressure plate on the energy-absorbing and anti-impact characteristics of energy-absorbing members were analysed. The results show that the deformation process and resistance trend of the torsion plate correspond to energy absorption. The resistance stability is high in the reaction force platform stage, and the energy increases linearly. With the increase of the torsion angle, the mean value of the reaction force increases, the fluctuation of the reaction force platform stage becomes more obvious, the specific energy absorption increases linearly, and the standard deviation reaches the minimum at 480°. Both the tensile length and the length of the reaction force platform stage increase continuously. With the increase of the plate thickness, the flatness of the torsion plate shows a trend of bad-good-bad, the mean value of the reaction force gradually increases, the specific energy absorption grows faster and then slower, and the tensile length and the length of the reaction force platform stage increase accordingly. With the increase of the fillet radius, the flatness of the torsion plate is better and the reaction force has a small improvement. The fluctuation of reaction force is most significant when the fillet radius is 2 mm, and the energy-absorbing member has the largest swing. The specific energy absorption is highest when the fillet radius is 2.5 mm, the standard deviation shows a tendency to develop firstly decreasing and then stabilising, the tensile length of the torsion plate decreases slightly, and the length of the reaction force platform firstly increases and then tends to stabilise. The torsion plate energy-absorbing member is a more ideal energy-absorbing and anti-impact member, which plays a positive role in the energy-absorbing and anti-impact of the hydraulic support. [ABSTRACT FROM AUTHOR]

A nitrogen‐centered heptalene, azaheptalene, was designed as a representative of a new class of redox‐responsive molecules with a large steric strain that originates from the adjacent seven‐membered rings. The pentabenzo derivative of azaheptalene was efficiently synthesized by a palladium‐catalyzed one‐pot reaction of commercially available reagents. Bromination led to mono‐ and dibrominated derivatives, the latter of which is interconvertible with isolable radical cation species exhibiting near‐infrared absorption. Since the azaheptalene skeleton shows configurationally stable helicity with a large torsion angle, enantiomers could be successfully separated. Thus, optically pure azaheptalenes with P‐ or M‐helicity showed strong chiroptical properties (|gabs|≥0.01), which could be changed by an electric potential. [ABSTRACT FROM AUTHOR]

The present work reports the synthesis of two simple tailor-made anils (o-hydroxybezylidene-orthochloroaniline & o-hydroxynaphthalidene-orthochloroaniline) and their characterization by 1H & 13C Nuclear magnetic resonance(NMR), single X-ray diffraction spectroscopy(SC-XRD) and DFT studies. DFT-B3LYP optimized the molecular structures with a 6-311G (d, p) basis set to accomplish the global minimum energy state. 1H NMR confirmed the occurrence of H-bonding between the phenolic hydrogen and azomethine nitrogen in both molecules, further supported by SC-XRD analysis and DFT studies. The structural parameters such as bond angle, bond length, and dihedral angle derived from the optimized structure of molecules with C1 symmetry were compared with the corresponding parameters extracted from the ORTEP diagrams for both anils. Appreciable harmony of the structural parameters was achieved between these two analyses, confirming the anils' purity. Slight discrepancy observed between DFT and SC-XRD analyses was attributed to the difference in the state of the molecules. Geometric optimization indicated the molecules to be coplanar. The MEP surface and atomic charges on the atoms envisaged the electron population and charged sites of the anils. Conclusively, both the anils have a suitable structural hierarchy for superior electron transport from the phenyl rings over the entire molecular framework suitable for optoelectronics applications. [ABSTRACT FROM AUTHOR]

In order to meet the requirements of autonomous docking and combined flight of unmanned aerial vehicles （UAVs）, the aerodynamic configuration of six-ducted UAV was designed. The aerodynamic characteristics of the UAV in hover condition were studied by numerical simulation, the aerodynamic performance changes of the whole machine under different propeller speeds were studied, and the aerodynamic optimization of the propeller was carried out under the duct condition. The results show that the propeller is the main source of hover lift, and with the change of rotation speed, the lift force of the duct always accounts for about 17% of the total lift force. The resistance comes from the upper surface of the vehicle and the motor support, which reaches 10% of the total lift of the UAV. With the increase of the propeller plate load, the power load of UAV decreases. The presence of the duct affects the slip flow characteristics of the propeller, resulting in the increase of the axial speed of the propeller disc, the decrease of the angle of attack of the section airfoil, and the decrease of the working efficiency. By adjusting the distribution of the torsion angle, the propeller efficiency is improved, the lift is increased by 3.3%, and the efficiency is increased by 2.9%. [ABSTRACT FROM AUTHOR]

Low band gap materials have always been a focus of attention due to their potential applications in various fields. In this work, a series of asymmetric bistricyclic aromatic ene (BAE) compounds with fluorenylidene‐cyclopentadithiophene (FYT) skeleton were facially synthesized, which were modified with different substituents (−OMe, −SMe). The FYT core exhibit twisted C=C bond with dihedral angles around 30°, and the introduction of −SMe group can provide additional S⋅⋅⋅S interaction between molecules, which is conducive to the charge transporting. The UV‐Vis spectra, electrochemistry and photoelectron spectroscopy revealed that these compounds have relatively narrow band gaps, particularly, the −SMe modified compounds have slightly lower HOMO and Fermi energy levels than that of the −OMe modified compounds. Furthermore, PSCs devices were fabricated with the three compounds as HTMs, and FYT‐DSDPA exhibit the best performance among them, revealing the fine‐tuning band structure could influence properties of HTMs. [ABSTRACT FROM AUTHOR]

Context: The dye-sensitized solar cell is a technology unique in its light conversion properties as it operates with record efficiencies in diffused light conditions. The choice of the appropriate sensitizer is one of the important strategies to improve photovoltaic performance of DSSC devices. This theoretical study mainly aims to determine the impact of the π-spacer on the geometric and optoelectronic parameters of sensitizer dyes. For that, we have chosen six organic dyes of Donor-π-Acceptor structure based on triphenylamine unit as electron donor, cyanoacrylic acid as electron acceptor with various π-bridges. The results indicated that the doping process modify dihedral angles and electronic properties by enhancing the planarity and decreasing the gap energy. We have examined the optoelectronic and photovoltaic properties of studied triphenylamine based-dyes. Introducing thiophene and furan as π-spacer groups in D6 dye can effectively decrease the gap energy (Egap = 2.21 eV), broaden the absorption range (λmax = 671.19 nm), and promote the light-harvesting properties. The D2 dye based on two pyrrole units presents an improved electron injection driving force (ΔGinject = − 2.269 eV) and regeneration driving force corresponding to better charge separation. The π-bridge groups can efficiently tune the optoelectronic and photovoltaic properties of sensitizers, which contribute to the efficiency of solar cells. Methods: The geometrical and electronic properties of all systems were studied by the DFT method using the correlation exchange functional B3LYP combined with 6-31G(d, p) basis set. On the other hand, the maximum absorption wavelengths λmax and the corresponding oscillator strengths were calculated using the hybrid functional BHandHLYP and 6-31+G(d) basis set. The solvent tetrahydrofuran (THF) are used to study the effect of the solvent, using the "Conductor-Polarizable Continuum" (C-PCM) model. All calculations were performed using Gaussian 09 program. [ABSTRACT FROM AUTHOR]

The title compound, C11H3I3N4O4.C2H6O, crystallizes in the triclinic P1 space group with one independent molecule and one ethanol solvent molecule in the asymmetric unit. The benzene ring and the methylcarbonohydrazonoyl dicyanide group of the main molecule makes a dihedral angle of 57.91 (16). In the crystal, O--H..O and N--H...O hydrogen bonds link pairs of molecules, forming dimers with R2 2(14) motifs. These dimers are connected by O--H...O hydrogen bonds into chains along the a-axis direction, forming R2 2(16) ring motifs. Further O--H...O interactions involving the ethanol solvent molecule connect the chains into a three-dimensional network. In addition, C--I... interactions are observed. The intermolecular interactions in the crystal structure were quantified and analysed using Hirshfeld surface analysis. [ABSTRACT FROM AUTHOR]

Origami crash tubes have concerned nowadays due to their superior crashworthiness behaviour by controlling the initial buckling force and collapse modes. In this paper, a new multi-layered origami pattern is proposed and fabricated, and a numerical study is performed under quasi-static axial compressive loading and validated by the experimental result of the fabricated origami crash box. To compare the energy absorption efficiency of this proposed origami tube, its mechanical responses are normalised with the conventional octagonal tube. Moreover, the crashworthiness behaviour of 64 samples is investigated for the dihedral angle 2θ, outer layer height e, and module number M in the parametric study. It is demonstrated that by increasing M for tubes with a constant value of e, the critical angle of θ decreases. By increasing the value of e for tubes; while, considering the values of M and θ constant, the mechanical responses of the tubes increase, and these trends are valid as long as θ is below the critical angle. The number of modules M, angle θ, and outer layer height e have the highest effect on the mechanical responses. Finally, the results show that by maintaining the specific energy absorption of the conventional octagonal tube, the initial peak force can be reduced about 55%. In consequence, the proposed pattern reduces the initial peak force while maintaining the specific energy absorption. [ABSTRACT FROM AUTHOR]

Macrophage infectivity potentiator (Mip) protein, an essential virulence factor encoded by pathogenic bacteria such as Legionella pneumophila, arises as an interesting new therapeutic target for novel antimicrobials. However, Mip- ligands also interact with FKBP12 protein, a human FKBP exhibiting immunosuppressive effects. Therefore, these ligands are unsuitable antibiotics. Understanding the dynamics and conformations of proteins in the binding pocket is important to predict binding properties and to design new binders for different FKBPs. We performed the 40 ns combined classical and flooding molecular dynamics simulations using additional flooding potential for Mip-rapamycin and FKBP12-rapamycin complexes. Both complexes have different flexibilities and dihedral angle principal component analysis calculated from MD trajectories. As a result, the Mip-rapamycin complex had more conformations than the FKBP12- rapamycin complex. These different features of both complexes at the binding pocket will provide new dues for the design of selective inhibitors of Mip proteins. [ABSTRACT FROM AUTHOR]

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High‐contrast mechano‐responsive luminescence (MRL) materials with mechano‐induced emission enhancement properties are fascinating candidates but few, for applications in rewritable media and recording devices. Here, an interesting design strategy of "Y‐shape" donor‐acceptor (D−A) type molecules for high‐contrast MRL materials was presented, based on substituted diphenylamine donor and planar acceptor. Interestingly, their D−A torsion angles are small in crystals but increased after ground, resulted in planar and twist intramolecular charge transfer (PICT and TICT) states, respectively. Therefore, high‐contrast MRL switching between weak blue (450 nm) fluorescence and bright yellow (552 nm) thermally activated delayed fluorescence (TADF) can be achieved for compound TXDO (4,4′‐dimethoxydiphenylamine donor), which photoluminescence quantum yield increased from 2.8 % to 54.7 % after ground. Most importantly, the two independent D−A conjugation dihedral angles are actually independent in the "Y‐shape" molecules. Especially for compound TXDT (4,4′‐di‐tert‐butyldiphenylamine donor), its crystal exhibited both PICT and TICT processes inside, resulted from the different dihedral angles of 11.8° and 35.5°, respectively. The TXDT crystal thus showed dual‐peak emission, including both TICT fluorescence and PICT room‐temperature phosphorescence. Therefore, this strategy of "Y‐shape" D−A type molecules provide a new approach to design advanced luminescent materials with mechano‐induced TADF feature, for high‐contrast MRL and single‐component white luminescence. [ABSTRACT FROM AUTHOR]

Highlights: What are the main findings? The ME molecule has 21 stable configurations. For all the tops (except =CH2), the barrier heights are of the same order, while the =CH2 top has a barrier height one order of magnitude higher. Like estragole and eugenol, ME also has the same Fermi doublets for the following modes: νs(–CH2) and 2 × βs(–CH2); νs(CH3) and 2 × δs(CH3). The ME molecule has three active sites. Vibrational analysis suggests that the solvents affect the internal modes of both OCH3 moieties strongly. What is the implication of the main finding? The methyl-eugenol molecule could be a good choice for the pharmacological applications The OCH3 moieties of methyl-eugenol play significant role in interaction with other molecules. Structural, conformational, and spectroscopic investigations of methyl-eugenol were made theoretically at the B3LYP-6-311++G**level. Experimental IR, Raman, and UV-vis spectra were investigated and analyzed in light of the computed quantities. Conformational analysis was carried out with the help of total energy vs. dihedral angle curves for different tops, yielding 21 stable conformers, out of which only two have energies below the room temperature relative to the lowest energy conformer. The effect of the solvent on different molecular characteristics was investigated theoretically. MEP and HOMO-LUMO analysis were carried out and barrier heights and bioactivity scores were determined. The present investigation suggests that the molecule has three active sites with moderate bioactivity. The solvent–solute interaction is found to be dominant in the vicinity of the methoxy moieties. [ABSTRACT FROM AUTHOR]

A systematic study on the distortion of a naphthalene ring was performed using steric repulsion between peri-substituents at the 1- and 8-positions. The introduction of bromo groups into the methyl groups of the 1,8-dimethylnaphthalene enhanced the steric repulsion to distort the naphthalene ring. X-ray crystallography revealed that 1,8-bis(bromomethyl)naphthalene had a vertical distortion with a 11.0° dihedral angle (α) between peri-substituents which disturbed the coplanarity of the naphthalene ring. On the other hand, the dihedral angle of 1,8-bis(dibromomethyl)naphthalene was smaller (α = 8.3°) despite the bulkier substituents. In this case, horizontal distortion of the naphthalene ring increased. These distortions should non-electronically activate the naphthalene framework. In order to evaluate their reactivity, nitration and hydrogenation were carried out; however, the 1,8-bis(dibromomethyl)naphthalene was intact under the employed conditions. A DFT calculation suggested that the inertness of the 1,8-bis(dibromomethyl)naphthalene is presumably due to the negative hyperconjugation of the (dibromo)methyl group. [ABSTRACT FROM AUTHOR]

A family of five- and six-coordinated Fe-porphyrins which enable us to scrutinize the effects of non-covalent interactions on the out-of-plane displacement of iron and its spin-states and axial ligand orientation in a single distorted macrocyclic environment has been reported. Combined analysis using single-crystal X-ray structure determination and EPR spectral investigation revealed the stabilization of the high-spin state of iron in the five-coordinate complex FeIII(TPPBr8)(OCHMe2), while six-coordinate complexes [FeIII(TPPBr8)(MeOH)2]ClO4, [FeIII(TPPBr8)(H2O)2]ClO4 and [FeIII(TPPBr8)(1-MeIm)2]ClO4 stabilize admixed-high, admixed-intermediate and low-spin states, respectively. The H-bonding interactions between the weak axial H2O/MeOH and perchlorate anion resulted in an elongation of the Fe–O bond which eventually shortened the Fe–N(por) distances leading to the stabilization of the admixed spin state of iron which, otherwise, stabilizes the high-spin (S = 5/2) state only. In addition, the iron atom in [FeIII(TPPBr8)(H2O)2]ClO4 is displaced by 0.02 Å towards one of the water molecules engaged in the H-bonding interactions leading to two different Fe–O (H2O) distances of 2.098(8) and 2.122(9) Å. In contrast, iron in [FeIII(TPPBr8)(MeOH)2]ClO4 sits on the plane of the porphyrin since both the axial methanol units are engaged in similar H-bonding interactions with the ClO4− ion. Moreover, the X-ray structure of low-spin FeII(TPPBr8)(1-MeIm)2 revealed a dihedral angle of 63.0° between two imidazoles which deviates largely from the expected angle of 90° (perpendicular orientations) since the axial imidazole protons are engaged in strong intermolecular C–H⋯π interactions which thereby restrict the axial ligand movement. The complex also displays the shortest Fe–N(1-MeIm) bond along with smallest dihedral angles of 7.8° and 22.4° between the axial imidazole ring and the closest Fe–Np axis due to strong π-interactions between iron and the axial imidazole ligand. Our work highlights the influence of non-covalent interactions on the out-of-plane displacement and spin state of iron and axial ligand orientations which are indeed important steps in the functioning of various hemoproteins. [ABSTRACT FROM AUTHOR]

Increasing the repertoire of available complementary tools to advance the knowledge of protein structures is fundamental for structural biology. The Neighbors Influence of Amino Acids and Secondary Structures (NIAS) is a server that analyzes a protein's conformational preferences of amino acids. NIAS is based on the Angle Probability List, representing the normalized frequency of empirical conformational preferences, such as torsion angles, of different amino acid pairs and their corresponding secondary structure information, as available in the Protein Data Bank. In this work, we announce the updated NIAS server with the data comprising all structures deposited until Sep 2022, 7 years after the initial release. Unlike the original publication, which accounted for only studies conducted with X-ray crystallography, we added data from solid nuclear magnetic resonance (NMR), solution NMR, CullPDB, Electron Microscopy, and Electron Crystallography using multiple filtering parameters. We also provide examples of how NIAS can be applied as a complementary analysis tool for different structural biology works and what are its limitations. [ABSTRACT FROM AUTHOR]

Motivation Identifying the probable positions of the protein side-chains is one of the protein modelling steps that can improve the prediction of protein–ligand and protein–protein interactions. Most of the strategies predicting the side-chain conformations use predetermined dihedral angle lists, also called rotamer libraries, that are usually generated from a subset of high-quality protein structures. Although these methods are fast to apply, they tend to average out geometries instead of taking into account the surrounding atoms and molecules and ignore structures not included in the selected subset. Such simplifications can result in inaccuracies when predicting possible side-chain atom positions. Results We propose an approach that takes into account both of these circumstances by scanning through sterically accessible side-chain conformations and generating dihedral angle libraries specific to the target proteins. The method avoids the drawbacks of lacking conformations due to unusual or rare protein structures and successfully suggests potential rotamers with average RMSD closer to the experimentally determined side-chain atom positions than other widely used rotamer libraries. Availability and implementation The technique is implemented in open-source software package rotag and available at GitHub: https://www.github.com/agrybauskas/rotag , under GNU Lesser General Public License. [ABSTRACT FROM AUTHOR]

In steam turbines, the operation of turbine blades can lead to vibrations, which may result in turbine accidents. Traditional calculation methods are difficult to use due to the complex structure of the torsional blade, and simulation analysis can be time-consuming. Therefore, it is necessary to use the equivalent model instead. Most of the previous studies have simplified the straight blade to a cantilever beam model without considering the shear effect, and used harmonic response analysis to study the vibration of the blade for simulation. The blade body of the torsional blade can be regarded as a torsional variable section beam, and the Timoshenko beam model is the same as the variable section beam. Therefore, the Timoshenko beam model can be regarded as the equivalent of the sheathed torsional blade. Considering the complexity of the calculation of the self-shrouded torsional blade model. According to the theory of Timoshenko beam, the model of the shrouded blade of Timoshenko beam with different torsion angles was established. The first sixth-order modes of the blade model and the vibration response of the adjacent blades under forced vibration are compared, respectively. The results show that the results obtained from the Timoshenko beam blade model considering the torsion angle are closer to the torsional blade model. In addition, the blade vibration response of the same model under different excitation force amplitudes was further compared, and the results showed that the vibration amplitude, acceleration and velocity of the shrouded blade increased with the increase of the excitation force amplitude. However, the magnitude of the inter-shroud collision force and the number of collisions between adjacent blade shrouds are non-linearly related to the amplitude of the excitation force. [ABSTRACT FROM AUTHOR]

Simple Summary: This study aimed to create an intelligent computer model called TAFPred to predict how proteins move and twist by looking at their sequences. By analyzing different features of the protein sequences, the model can accurately estimate the degree of flexibility of protein structures per residue. The investigators used an advanced machine learning technique called LightGBM to make these predictions even better. Compared to existing methods, TAFPred significantly improved in accurately predicting how proteins bend and twist within the individual and collective residual degree of freedom. This study is vital because understanding protein flexibility helps us know how they function in our bodies. By improving our ability to predict protein movements, this study brings us closer to unlocking the secrets of how proteins work and the role of protein flexibility in cellular functions, which can have critical applications in medicine and biology. Protein molecules show varying degrees of flexibility throughout their three-dimensional structures. The flexibility is determined by the fluctuations in torsion angles, specifically phi (φ) and psi (ψ), which define the protein backbone. These angle fluctuations are derived from variations in backbone torsion angles observed in different models. By analyzing the fluctuations in Cartesian coordinate space, we can understand the structural flexibility of proteins. Predicting torsion angle fluctuations is valuable for determining protein function and structure when these angles act as constraints. In this study, a machine learning method called TAFPred is developed to predict torsion angle fluctuations using protein sequences directly. The method incorporates various features, such as disorder probability, position-specific scoring matrix profiles, secondary structure probabilities, and more. TAFPred, employing an optimized Light Gradient Boosting Machine Regressor (LightGBM), achieved high accuracy with correlation coefficients of 0.746 and 0.737 and mean absolute errors of 0.114 and 0.123 for the φ and ψ angles, respectively. Compared to the state-of-the-art method, TAFPred demonstrated significant improvements of 10.08% in MAE and 24.83% in PCC for the phi angle and 9.93% in MAE, and 22.37% in PCC for the psi angle. [ABSTRACT FROM AUTHOR]

Outer membrane proteins (OMPs) must exist as an unfolded ensemble while interacting with a chaperone network in the periplasm of Gram-negative bacteria. Here, we developed a method to model unfolded OMP (uOMP) conformational ensembles using the experimental properties of two well-studied OMPs. The overall sizes and shapes of the unfolded ensembles in the absence of a denaturant were experimentally defined by measuring the sedimentation coefficient as a function of urea concentration. We used these data to model a full range of unfolded conformations by parameterizing a targeted coarse-grained simulation protocol. The ensemble members were further refined by short molecular dynamics simulations to reflect proper torsion angles. The final conformational ensembles have polymer properties different from unfolded soluble and intrinsically disordered proteins and reveal inherent differences in the unfolded states that necessitate further investigation. Building these uOMP ensembles advances the understanding of OMP biogenesis and provides essential information for interpreting structures of uOMP-chaperone complexes. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Deep ultraviolet (UV) photodetectors have important applications in the industrial and military fields. However, little research has been reported on organic phototransistors (OPTs) in the deep ultraviolet range. Here, a novel organic semiconductor containing a small torsion angle and low π‐conjugation 2,2':5',2"‐terthiophene groups, oF‐PTTTP, is designed and synthesized, which exhibits high carrier mobility and unique deep ultraviolet response. Accordingly, an OPT based on oF‐PTTTP single crystal shows high responsivity to deep‐UV light. The photodetectors achieve high photoresponsivity (R) of 857 A/W and detectivity (D*) of 3.2×1015 Jones under 280 nm light illumination (only 95 nW·cm–2). To the best of our knowledge, 280 nm is the deepest detection wavelength reported for organic phototransistors and this work presents a new molecule design concept for organic phototransistors with deep‐UV detection. [ABSTRACT FROM AUTHOR]

The scoring models used for protein structure modeling and ranking are mainly divided into unified field and protein-specific scoring functions. Although protein structure prediction has made tremendous progress since CASP14, the modeling accuracy still cannot meet the requirements to a certain extent. Especially, accurate modeling of multi-domain and orphan proteins remains a challenge. Therefore, an accurate and efficient protein scoring model should be developed urgently to guide the protein structure folding or ranking through deep learning. In this work, we propose a protein structure global scoring model based on equivariant graph neural network (EGNN), named GraphGPSM, to guide protein structure modeling and ranking. We construct an EGNN architecture, and a message passing mechanism is designed to update and transmit information between nodes and edges of the graph. Finally, the global score of the protein model is output through a multilayer perceptron. Residue-level ultrafast shape recognition is used to describe the relationship between residues and the overall structure topology, and distance and direction encoded by Gaussian radial basis functions are designed to represent the overall topology of the protein backbone. These two features are combined with Rosetta energy terms, backbone dihedral angles and inter-residue distance and orientations to represent the protein model and embedded into the nodes and edges of the graph neural network. The experimental results on the CASP13, CASP14 and CAMEO test sets show that the scores of our developed GraphGPSM have a strong correlation with the TM-score of the models, which are significantly better than those of the unified field score function REF2015 and the state-of-the-art local lDDT-based scoring models ModFOLD8, ProQ3D and DeepAccNet, etc. The modeling experimental results on 484 test proteins demonstrate that GraphGPSM can greatly improve the modeling accuracy. GraphGPSM is further used to model 35 orphan proteins and 57 multi-domain proteins. The results show that the average TM-score of the models predicted by GraphGPSM is 13.2 and 7.1% higher than that of the models predicted by AlphaFold2. GraphGPSM also participates in CASP15 and achieves competitive performance in global accuracy estimation. [ABSTRACT FROM AUTHOR]

The characteristic absorption spectra of three positional isomers of hydroxybenzoic acid are measured using a terahertz time-domain spectroscopy system (THz-TDS) in the 0.6–2.0 THz region at room temperature. Significant differences in their terahertz spectra are discovered, which indicates that THz-TDS is an effective means to identify positional isomers. In order to simulate their spectra, the seven molecular clusters of 2-, 3-, and 4-hydroxybenzoic acid (2-, 3-, and 4-HA) are calculated using the DFT-D3 method. Additionally, the potential energy distribution (PED) method is used to analyze their vibration modes. The analysis indicates that the vibration modes of 2-HA are mainly out-of-plane angle bending and bond angle bend in plane. The vibration modes of 3-HA are mainly bond length stretch and dihedral angle torsion. The vibration modes of 4-HA are mainly bond angle bend in plane and dihedral angle torsion. Interaction region indicator (IRI) analysis is used to visualize the location and type of intermolecular interactions in 2-, 3-, and 4-HA crystals. The results show that the weak interaction type of 2-, 3-, and 4-HA is dominated by van der Waals (vdW) interaction. Therefore, we can confirm that terahertz spectroscopy detection technology can be used as an effective means to identify structural isomers and detect the intermolecular interactions in these crystals. In addition, it can explain the absorption mechanism of terahertz waves interacting with matter. [ABSTRACT FROM AUTHOR]

Purpose: Any consensus about the effects of dihedral angle on hover rigidity of rotary-wing unmanned aerial vehicles (RW-UAVs) does not exist in the literature. There are researchers who state that the dihedral angle has an effect on flight stability and researchers who claim the opposite. The discord stems from the different approaches of these groups to the concept of "stability," the fact that they conduct experiments whose measurements are largely influenced by environmental conditions, and the physical assumptions are not similar. On the other hand, there is no study examining the effect of dihedral angle on the maneuverability of drones either. This study aims to analytically reveal the consequences of dihedral angles in RW-UAVs in terms of flight agility and maneuverability. Design/methodology/approach: Dihedral angle examinations on both hover rigidity and maneuverability are carried out analytically. Equations of motions for a multicopter's rigid body with a dihedral angle under two different conditions (zero and nonzero dihedral angles) are derived. Numerical simulations are conducted by defining the simulation parameters, and then displacement graphics for the center of mass are interpreted. Findings: The presence of a dihedral angle makes the multicopter platforms behave like a pendulum, and this pendulum motion affects the disturbance rejection and the planar maneuver capabilities of multicopters. Since deflections can be spread to the orthonormal axes thanks to rotation about a pivot, net deflections of the geometric center may be diminished. Besides, pendulum motion eases the maneuvers with yaw rotations since the required rotation might occur without rotors' revolution per minute changes. Practical implications: Proposed dihedral angle implementation may enhance the hover stiffness and maneuverability capabilities of multicopters which, in turn, raise the performance of the drones. Originality/value: This paper presents the analytical basis for the dihedral angle's effects on flight stability and agility. [ABSTRACT FROM AUTHOR]

The title benzimidazole compounds, namely, 2‐(4‐methoxynaphthalen‐1‐yl)‐1H‐benzo[d]imidazole, C18H14N2O (I) and 2‐(4‐methoxynaphthalen‐1‐yl)‐1‐[(4‐methoxynaphthalen‐1‐yl)methyl]‐1H‐benzo[d]imidazole ethanol monosolvate, C30H24N2O2·C2H6O (II), were synthesized by the condensation reaction of benzene‐1,2‐diamine with 4‐methoxynaphthalene‐1‐carbaldehyde in the ratios 1:1 and 1:2, respectively. In I, the mean plane of the naphthalene ring system is inclined to that of the benzimidazole ring by 39.22 (8)°, while in II, the corresponding dihedral angle is 64.76 (6)°. This difference is probably influenced by the position of the second naphthalene ring system in II; it is inclined to the benzimidazole ring mean plane by 77.68 (6)°. The two naphthalene ring systems in II are inclined to one another by 75.58 (6)°. In the crystal of I, molecules are linked by N—H...N hydrogen bonds to form chains propagating along the a‐axis direction. Inversion‐related molecules are also linked by a C—H...π interaction linking the chains to form layers lying parallel to the ac plane. In the crystal of II, the disordered ethanol molecule is linked to the molecule of II by an O—H...N hydrogen bond. There are a number of C—H...π interactions present, both intra‐ and intermolecular. Molecules related by an inversion centre are linked by C—H...π interactions, forming a dimer. The dimers are linked by further C—H...π interactions, forming ribbons propagating along the b‐axis direction. The interatomic contacts in the crystal structures of both compounds were explored using Hirshfeld surface analysis. The molecular structures of I and II were determined by density functional theory (DFT) calculations at the M062X/6‐311+g(d) level of theory and compared with the experimentally determined molecular structures in the solid state. Local and global reactivity descriptors were computed to predict the reactivity of the title compounds. Both compounds were shown to exhibit significant anticorrosion properties with respect to iron and copper. [ABSTRACT FROM AUTHOR]

Five new Schiff bases synthesized by the reaction between 2-(methylthio)aniline derivatives and p-methoxysalicylaldehyde are presented as MtH-1 (R = H), MtH-2 (R = CH3), MtH-3 (R = OCH3), MtH-4 (R = Cl) and MtH-5 (R = Br). They were characterized by CHNS analyses, NMR (¹H, 13C, DEPT135, COSY and HSQC), FTIR and UV-Vis spectroscopic techniques. FT-IR, elemental analyses and NMR data supported the formation of the Schiff bases, with the chemical shifts of azomethine and phenol protons showing sensitivity to ring substitution. The crystal structure of MtH-1 featured the alignment of the phenyl rings to each other and to the C=N group with dihedral angles >170°. The DFT calculations corroborated the bond lengths and angles of MtH-1. The HOMO-LUMO energies, dipole moments and other reactivity parameters were calculated. The methyl-substituted MtH-2 was the least polar of the compounds. With calculated energy band gaps of almost 4 eV, the compounds may have applications in the semiconductors field. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to solve a series of problems, such as the difficulty in accurately controlling the specific surfaces, and the interference between the laser beam and the part, when the laser is used to clean mechanical parts with complex surfaces by using robots. Firstly, a region segmentation algorithm of the stereo lithography (STL) model was designed, and the feature surfaces of the model were obtained by using the dihedral angle as the criterion. Then the path points which could easily cause interference between the laser beam and the part to be cleaned were detected by the method of ray intersection, and the pose of the robot was modified according to the normal vectors of two non-interference points that were adjacent to the continuous interference points respectively. Finally, the proposed method was validated by scanning path visualization and robot laser cleaning process experiments. The generated path in the unit of feature surface according to the variation components of normal vectors proved the effectiveness of the STL model region segmentation algorithm based on dihedral angle division criteria; the change of the normal vectors of the path points on the current feature surface was continuous and smooth, which meant that the path points did not cause sudden change of the robot pose after the pose correction. The robot cleaned the specific surfaces of the test workpiece safely and effectively in the actual laser cleaning experiments, and the effective cleaning area reached 96.87%, 99.56%, 94.53% and 91.62% of the target cleaning area, which further proved the effectiveness of this study. The method is also useful for the path planning of robots in other processing fields. [ABSTRACT FROM AUTHOR]

The synthesis, crystal structure and spectroscopic analysis of (E)-1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-3-(4-chlorophenyl)prop-2-en-1-one (C17H13ClO3), a substituted chalcone, are described. The overall geometry of the molecule is largely planar (r.m.s. deviation = 0.1742 JA), but slightly kinked, leading to a dihedral angle between the planes of the benzene rings at either side of the molecule of 8.31 (9)°. In the crystal, only weak interactions determine the packing motifs. These include C--H--O and C--H--Cl hydrogen bonds and n-n overlap of aromatic rings. [ABSTRACT FROM AUTHOR]

The synthesis and crystal structure of a monoclinic polymorph of 2-amino-5-chlorobenzophenone oxime, C13H11ClN2O, are presented. The molecular conformation results from twisting of the phenyl and 2-amino-5-chloro benzene rings attached to the oxime group, which subtend a dihedral angle of 80.53 (4)°. In the crystal, centrosymmetric dimers are formed as a result of pairs of strong O--H--N hydrogen bonds. A comparison is made to a previously known triclinic polymorph, including differences in atom-atom contacts obtained via a Hirshfeld-surface analysis. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Deep ultraviolet (UV) photodetectors have important applications in the industrial and military fields. However, little research has been reported on organic phototransistors (OPTs) in the deep ultraviolet range. Here, a novel organic semiconductor containing a small torsion angle and low π‐conjugation 2,2':5',2"‐terthiophene groups, oF‐PTTTP, is designed and synthesized, which exhibits high carrier mobility and unique deep ultraviolet response. Accordingly, an OPT based on oF‐PTTTP single crystal shows high responsivity to deep‐UV light. The photodetectors achieve high photoresponsivity (R) of 857 A/W and detectivity (D*) of 3.2×1015 Jones under 280 nm light illumination (only 95 nW·cm–2). To the best of our knowledge, 280 nm is the deepest detection wavelength reported for organic phototransistors and this work presents a new molecule design concept for organic phototransistors with deep‐UV detection. [ABSTRACT FROM AUTHOR]

An efficient method was proposed to fabricate the mold cavity for a helical cylindrical pinion based on a plastic torsion forming concept. The structure of the spur gear cavity with the same profile as the end face of the target helical gear cavity was first fabricated by low-speed wire electrical discharge machining (LS-WEDM). Then, the structure of the helical gear cavity could be obtained by twisting the spur gear cavity plastically around the central axis. In this way, the fabrication process of a helical cylindrical gear cavity could be greatly simplified, compared to the fabrication of a multi-stage helical gear core electrode and the highly difficult and complex spiral EDM process in the current gear manufacturing method. Moreover, several experiments were conducted to verify this novel processing concept, and a theoretical model was established to show the relationship between the machine torsion angle and the helical angle of a helical gear. Based on this theoretical model, the experimental results showed that it is feasible to precisely control the shape accuracy of a helical cylindrical pinion mold cavity by adjusting the machine torsion angle. [ABSTRACT FROM AUTHOR]

The Povarov reaction is a representative multicomponent reaction used for synthesizing nitrogen‐containing aromatic compounds from aromatic amines, aldehydes, and dienophiles, such as electron‐rich alkenes and alkynes. In this study, we investigated a triple Povarov reaction of 1,3,5‐triaminobenzne with aromatic aldehydes and phenylacetylene to obtain triazatriphenylene derivatives. Reactions with arylaldehydes containing electron‐donating groups proceeded smoothly to provide triazatriphenylene derivatives. In contrast, reactions with arylaldehydes containing electron‐withdrawing groups resulted in low yields. Reactions with electron‐rich arylaldehydes are probably more favorable in terms of high stability of imine intermediates and smooth electrophilic cyclization. Single‐crystal X‐ray structure analysis revealed that the aryl groups derived from the aldehydes had small dihedral angles between with the triazatriphenylene core. The derivative with tertiary butyl groups (tBu‐TaT) had a high glass transition temperature, while that without tertiary butyl groups (H‐TaT) had a lower highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) level and served as an efficient hole‐blocking material with better electron transport properties than those of tBu‐TaT. This study provides insights into the scope and limitations of the multicomponent reactions based on the Povarov reaction, substituent dependence on the crystal structures, and physical properties of π‐extended nitrogen‐containing aromatic compounds. [ABSTRACT FROM AUTHOR]