Angle Distortion Research Articles

The influence of welding speed on nanosecond laser welding of AZ31B magnesium alloy and 304 stainless steel

Nanosecond pulse laser welding was performed on AZ31B magnesium alloy and 304 stainless steel to investigate the impact of welding speed on the joining process. The temperature field of the magnesium/steel laser welding process was simulated using COMSOL software. The findings revealed that a welding speed of 10 mm/s resulted in significant spattering and larger porosity defects in the joint due to excessive heat input. However, when the welding speed was increased to 30 mm/s, these defects disappeared, and the porosity decreased to a minimum, leading to an increased bonding area at the interface. As the speed increased, the heat input decreased, making it more challenging for the porosity to escape from the molten pool and resulting in the formation of larger pores. The shear force test results indicated that the highest shear force was 298.7 N at a welding speed of 30 mm/s. The reduction in porosity and greater penetration depth of the magnesium alloy contributed to the desired mechanical performance. Additionally, the fracture modes were classified as button pullout failure (BPF), base material tearing failure (BTF), and interface failure (IF). The outermost weld seam served as the initial fracture path for both BPF and BTF modes, with BTF ultimately fracturing in the steel base material during tearing. Oxide inclusions, porosity, and the angle of distortion contributed to the fracture path of IF.

Оценка качественных признаков древесины в селекционных программах (краткий обзор современной литературы)

The literature review concerning wood quality traits measuring in forest tree breeding programs is given. Methods of wood density measuring by Pilodin and different types of Resistograph are shortly described. Comparison study to measure Scots pine wood density by Pilodin and Resistograph revealed that Resistograph provide more precise wood density data than Pilodin. Method of measuring of wood stiffness an important wood mechanical property using acoustic velocity data is characterized. There is relationship between distortion of lumber and grain angle of wood fibers. Grain angle, i.e. spiral grain, refers to the degree of helical deviation from longitudinal arrangement of wood fibers. It can be measured with a wedge grain angle gauge hammered into a stem of a standing tree. It is shown, that microfibril angle (MFA), referring to the deviation of cellulose microfibrils in the layer of the secondary cell wall from the long axis of cell, is the main determinant of the mechanical properties of wood. There is shortly described the system of instruments with linked software (SilviScan), the main components of this system are optical cell scanner (for measurement of fiber size), X-ray densitometer (density profile and others) and X-ray diffractometer (microstructure traits). A minor negative relationship between growth and wood quality traits is noted, so the index selection is recommended under realization of tree breeding program. Some examples of genomic selection in tree breeding programs for wood quality are given.

Correlation between parameters in the microstructural vector theory and Hill's plastic potential

The dissipation inequality provides a useful method for specifying constitutive equations of plastic deformation. There are two main ways to use the dissipation inequality to determine the plastic deformation path: by utilizing a plastic potential with the normality rule, or by not utilizing the plastic potential to determine the plastic flow according to the elastic distortion of the material coordinate axis (microstructural vectors). While both methods satisfy the inequality condition and predict experimental results well, they have been developed separately without discussion on relationship. This study presents a physics-based mathematical discussion on the relative dependence between the two methods of determining plastic flow and their point of connection, using Hill's quadratic plastic potential. For this, the conversion of the distortional length and angle changes in microstructural vectors to deviatoric strain tensor under small elastic deformation conditions is mathematically demonstrated. Using these equations, the rate of inelastic deformation derived from microstructural vectors exhibited a similar form to that derived from Hill's quadratic potential. Moreover, the model parameters of the microstructural vectors can be calibrated using the Hill's function. The plastic flow derived from the microstructural vectors and Hill's function exhibited a remarkably similar trend under the assumption of small elastic deformation, although not identical. The newly defined relationships were implemented numerically and validated through simulations. The parameters of the microstructural vector theory derived from Hill's plastic potential can be utilized in materials science and engineering.

Influence of pressure on elasticity, mechanical properties, and Li diffusion in battery electrode material LiCoO2: First-principles calculations

This study used first-principles calculations based on density functional theory with generalized gradient approximation (GGA) of the Perdew Burke and Ernzerhof (PBE) parameterized form to investigate the influence of pressure on the structural, elastic, and mechanical properties of rhombohedral LiCoO2. The results indicate that rhombohedral LiCoO2 remains stable up to 10 GPa. The calculated ground state properties agree well with experimental and other calculation data, validating the approach. Additionally, the calculated elastic constants, bulk modulus, Young's modulus, shear modulus, and Poisson's ratio at 0 GPa agree with previous results. The study found that all elastic constants continuously increase with increasing pressure. The deformation resistances along the axial direction are stronger than those in shape. The relationship between elasticity and length is such that C11 > C33, indicating that the incompressibility along the a axis is stronger than that along the c axis. The analysis of Poisson's ratio (ν) and Pugh's criterion B/G strongly suggests that rhombohedral LiCoO2 exhibits ductile behavior under pressure up to 10 GPa. The material is clearly anisotropic behavior, but the material exhibits improved isotropic behavior as pressure increases. Regarding Li ion diffusion in rhombohedral LiCoO2, the study found that the migration pathway for Li ions in rhombohedral LiCoO2 is a direct route that extends from the VLi site to the closest Li site. The diffusion process is hindered by a diffusion energy barrier of 0.87 eV, which is in good agreement with available theoretical data. Furthermore, the Li ion diffusion energy barrier increases with pressure because the decrease in dmean and polyhedral volume, along with changes in angle and torsional distortion factors of CoO6 octahedra, which can reduce the charging and discharging speeds of Li-ion batteries that use rhombohedral LiCoO2 as the cathode material.

Bent-Linear Isomerism and a Caveat on Bond Angle Distortion Anomalies in CpMo(NO)(η3-Methallyl)NCO

The displacement of the iodide ligand in (+)-(Cp)Mo(NO)(η3-methallyl)I, (+)-1, by treatment with silver(I) isocyanate yields (+)-(Cp)Mo(NO)(η3-methallyl)(NCO), (+)-2, with retention of configuration at the metal and was found to have the SMo configuration by X-ray crystallography. The X-ray data also showed the presence of two structure types in the unit cell of (+)-2, one bent and one linear with ∠MoNC bond angles of 154.4(4)° and 173.4(4)° respectively. In contrast, crystals of rac-2 show only one structure in the solid with an intermediate angle of 165.7(4). If (+)-2 is prepared via conversion of (+)-1 first to the carbonyl, by abstraction of iodide and treatment with CO, and subsequently sodium azide, yielded crystals of (+)-2 which showed varying angles ∠MoNC that appeared to be distortion isomers. Closer inspection of these products revealed an admixture of the intermediate azide compound, (+)-(Cp)Mo(NO)(η3-methallyl)N3, (+)-3, in the sample that was predominantly (+)-2. Mixtures of (+)-3 and (+)-2 or (-)-3 and (-)-2-co-crystallize and the results of X-ray structures of such mixtures appear to show 2 with varying bond angles ∠MoNC depending on the percentage of 3 in them. For example crystals with 85% of (-)-2 show ∠MoNC bond angles of 148.9(5)° and 171.9(5)°. This compares with the ∠MoNN in pure azide (+)-3 of 123.7(6)°

Asymmetric gradient orbital interaction of hetero-diatomic active sites for promoting C − C coupling

Diatomic-site catalysts (DACs) garner tremendous attention for selective CO2 photoreduction, especially in the thermodynamical and kinetical mechanism of CO2 to C2+ products. Herein, we first engineer a novel Zn-porphyrin/RuCu-pincer complex DAC (ZnPor-RuCuDAC). The heteronuclear ZnPor-RuCuDAC exhibits the best acetate selectivity (95.1%), while the homoatomic counterparts (ZnPor-Ru2DAC and ZnPor-Cu2DAC) present the best CO selectivity. In-situ spectroscopic measurements reveal that the heteronuclear Ru–Cu sites easily appear C1 intermediate coupling. The in-depth analyses confirm that due to the strong gradient orbital coupling of Ru4d–Cu3d resonance, two formed *CO intermediates of Ru–Cu heteroatom show a significantly weaker electrostatic repulsion for an asymmetric charge distribution, which result from a side-to-side absorption and narrow dihedral angle distortion. Moreover, the strongly overlapped Ru/Cu-d and CO molecular orbitals split into bonding and antibonding orbitals easily, resulting in decreasing energy splitting levels of C1 intermediates. These results collectively augment the collision probability of the two *CO intermediates on heteronuclear DACs. This work first provides a crucial perspective on the symmetry-forbidden coupling mechanism of C1 intermediates on diatomic sites.

Relationship between radiative characteristics and molecular geometry: Photophysical analysis of 2-phenylnaphthalene-appended ortho-carboranyl luminophores

This study investigates the photophysical features of aromatic conjugated o-carboranes and provides strong evidence for the relationship between their molecular geometry and photoluminescence efficiency. Four 2-phenylnaphthalene appended o-carboranyl luminophores, each with a different 2-phenyl ring distortion angle (1F, 2P, 3M, and 4I) were prepared and characterized. In particular, the geometric features around the 2-phenyl ring in the crystalline state were fully determined using single-crystal X-ray diffraction. All compounds in rigid states (solution at 77 K and solid states) demonstrated strong intramolecular charge-transfer (ICT)-based emissions in the yellowish-green region. Intriguingly, the quantum efficiency of the ICT-based emission gradually decreased as the distortion of the terminal 2-phenyl ring increased. Furthermore, the radiative decay constant of 1F was five times that of 4I, whereas the nonradiative decay of 1F was less than one-third that of 4I. In addition, theoretical modeling of the low-energy transition in the first excited state of 2P upon the rotation of the 2-phenyl ring revealed that the distorted geometry strongly affects the ICT-based radiative process. This model strongly suggests that the ICT-based radiative efficiency of π‒conjugated o-carborane is significantly affected by the geometry of the appended aromatic group.

Effect from usage and autoclave sterilization on torsional fracture resistance of heat-treated nickel-titanium instruments: an in-vitro study

This study aimed to evaluate the effect from usage and autoclaving on torsional fracture resistance of heat-treated nickel-titanium rotary instruments. ProTaper Gold F2 (PG) and TruNatomy Prime (TN) were selected. For group-N, new files were tested to make a baseline torsional resistance. For group-U, files underwent instrumentation in a J-shaped canal block, and files were tested. For group-S, files underwent instrumentation as in the group-U and followed by autoclave sterilization then were tested. Maximum torsional strength and distortion angel until fracture were measured using a customized device and toughness was calculated. Statistical analysis was conducted at the significance level of 95%. The topographic appearances of torsional fracture fragments were examined under scanning electron microscopy. PG showed significantly higher torsional strength after usage and sterilization; however, TN had reduced torsional strength (p < 0.05). PG showed significantly higher torsional strength in group-S than subgroup-N, while TN showed significantly lower torsional strength in group-U than group-N (p < 0.05). Regardless of the test conditions, PG showed significantly higher torsional strength and toughness than TN while TN had bigger distortion angle than PG (p < 0.05). The mechanical loads from usage and heat application during sterilization may result in alteration of torsional resistances according to geometry and alloy characteristics.

Synthesis and Structure of the Dicarboxyl-Terminated Iron(II) Tris-Glyoximates with Linear and Angular Geometry of their Molecules

Template condensation of the chelating α-dioximate ligand synthon—glyoxime and the appropriate cross-linking agent—monofunctionalized boronic (3-carboxyphenylboronic or 4-carboxyphenylboronic) Lewis acid in a boiling nitromethane as a solvent on the iron(II) ion as a matrix afforded the dicarboxyl-terminated iron(II) tris-glyoximates with functionalizing meta- and para-substituents in their apical boron-based aromatic fragments. The composition and structure of these macrobicyclic complexes were confirmed using elemental analysis, UV-vis, 1H and 13C{1H} NMR spectra. Their crystal and molecular structures were obtained by the single crystal X-ray diffraction experiments. Asymmetric units of their crystals contain, besides of a clathrochelate molecule, two solvate molecules, which form hydrogen bonds with its functionalizing carboxyl groups. The C–O bond lengths in these terminal groups and a possibility of localization of hydrogen atoms on the difference Fourier maps clearly demonstrate that the formation of such associates does not include a deprotonation of the macrobicyclic complex and its intracomplex molecules remain neutral. The encapsulated iron(II) ion in their molecules occupies a centre of its FeN6-coordination polyhedron. Its geometry is intermediate between a trigonal prism (TP, the distortion angle φ = 0°) and a trigonal antiprism (TAP, φ = 60°); the values of φ are equal to 17.1 and 18.9°, respectively. Fe–N distances vary from 1.901(2) to 1.924(2) Å, thus suggesting a low-spin diamagnetic state of the encapsulated iron(II) ion. The C=N bonds in the donor oxime groups are shortened, while the С–С bonds in the chelating glyoximate fragments are elongated, as compared with those in their aliphatic analogs. Free rotation of the apical aromatic substituents at the cross-linking boron atoms around the ordinary B–C bonds caused the absence of their coplanarity. The intramolecular distances С···С between the terminal carboxyl groups in the apical cross-linking fragments are equal to 15.693(4) and 17.888(3) Å for the clathrochelate meta- and para-isomers, respectively. The aforementioned rotation allows to achive an angular geometry of the prospective meta-dicarboxyloclathrochelate ligand with a formation of ∠C···Fe···C close to 145° between its terminal O‑donor carboxyl groups. This complex can play a role of both the angular and linear 3D-ligands, while its clathrochelate para-substituted isomer seems to be the prospective linear metalloligand.

Minimizing Bond Angle Distortion to Improve Thermal Stability of Cr3+ Doped Near‐Infrared Phosphor

AbstractBroadband near‐infrared (NIR) phosphor‐converted light‐emitting diodes are next‐generation smart NIR light sources. However, the NIR phosphor suffers from serious thermal quenching (TQ), resulting in efficiency reduction and spectral shift. Here, a novel strategy is realized to suppress TQ by minimizing bond angle distortion, completely different from the conventional TQ suppression approach through bond length variation. Li(Sr1−xCax)AlF6:Cr3+ NIR phosphor is taken as an example in which rotation between the two parallel fluorine planes perpendicular to the C3 axis in the [AlF6] octahedron is found to dominate TQ. Increasing x from 0 to 1 reduces the amplitude of the rotation from 16.17° to 5.06°, weakening the electron–phonon coupling and, consequently, raising the TQ temperature significantly from 320 to 570 K. This mechanism is elucidated from both theoretical calculations and spectroscopic studies. The findings open a new horizon for the exploration of thermally stable NIR phosphors.

Pr2CrMnO6 double perovskite as new electrode material for electrochemical energy storage

Single phase double perovskite oxide (Pr2CrMnO6) based new electrode material was developed for supercapacitor applications. Structural studies reveal monoclinic structure with space group P21/n. The sample exhibit bond angle distortion in the form of octahedral tilt. A signature of distortion in Mn — O — Cr bond angles is visualized through delocalization of oxygen clouds around Cr and Mn atoms via electron density maps. Large octahedral tilt in vertical direction forms uniform chain of spherical particles of mean size ∼870 nm. Electrochemical studies were performed by a three-electrode set up in room temperature. Both the cyclic voltametric and galvanic charge-discharge studies reveal great retention with variation in scanning parameters as well as cycles. The chain-like spherical-shaped particles anticipate active sites for intercalation and deintercalation of electrolyte ions that contributed towards diffusion-controlled capacitance. A significant value of specific capacitance (177.4 F/g) was achieved at current density of 2 A/g and it is found to be better than Ni–Mn based double perovskite oxides.

Visualizing defect dynamics by assembling the colloidal graphene lattice

Graphene has been under intense scientific interest because of its remarkable optical, mechanical and electronic properties. Its honeycomb structure makes it an archetypical two-dimensional material exhibiting a photonic and phononic band gap with topologically protected states. Here, we assemble colloidal graphene, the analogue of atomic graphene using pseudo-trivalent patchy particles, allowing particle-scale insight into crystal growth and defect dynamics. We directly observe the formation and healing of common defects, like grain boundaries and vacancies using confocal microscopy. We identify a pentagonal defect motif that is kinetically favoured in the early stages of growth, and acts as seed for more extended defects in the later stages. We determine the conformational energy of the crystal from the bond saturation and bond angle distortions, and follow its evolution through the energy landscape upon defect rearrangement and healing. These direct observations reveal that the origins of the most common defects lie in the early stages of graphene assembly, where pentagons are kinetically favoured over the equilibrium hexagons of the honeycomb lattice, subsequently stabilized during further growth. Our results open the door to the assembly of complex 2D colloidal materials and investigation of their dynamical, mechanical and optical properties.

Effect from Autoclave Sterilization and Usage on the Fracture Resistance of Heat-Treated Nickel–Titanium Rotary Files

This study aimed to assess the effect of mechanical loading and heating on the cyclic fatigue and torsional fracture resistances of heat-treated nickel-titanium files after usage and autoclaving. Sixty files (One Curve) were tested for cyclic fatigue and torsional fracture resistances using customized devices. The files were divided into three groups according to the test conditions (n = 10); new (group-N), used for simulated canal shaping (group-U), and sterilized after use (group-S). For cyclic fatigue resistances, the files were freely rotated in a curved metal canal under body temperature; the time elapsed to fracture was recorded and the numbers of cycles to fracture (NCF) were calculated. For the torsional resistances, the file tip was fixed and rotated until the file fractured. The maximum torsional load and distortion angle were recorded. The toughness was calculated. Fracture fragments were examined with a scanning electron microscope. Data were analyzed using a one-way analysis of variance and Tukey's post hoc test at the significance level of 95%. Group-U showed significantly higher NCF than group-S (p < 0.05). However, there was no significant differences between groups-N and -S in the NCF (p > 0.05). Group-N showed a significantly bigger distortional angle and higher torsional toughness than groups-U and -S, but the ultimate torsional strength did not have significant difference between the groups. Under the limitation of this study, autoclave sterilization after single-usage did not improve the fracture resistance of heat-treated One Curve nickel-titanium files.

Benzoxazole-Based Hybridized Local and Charge-Transfer Deep-Blue Emitters for Solution-Processable Organic Light-Emitting Diodes and the In fluences of Hexahydrophthalimido.

Hybridized local and charge-transfer (HLCT) emitters have attracted extensive attention, but the insolubility and severe self-aggregation tendency restrict their applications in solution-processable organic light-emitting diodes (OLEDs), particularly deep-blue OLEDs. Herein, two novel benzoxazole-based solution-processable HLCT emitters (BPCP and BPCPCHY) are designed and synthesized, in which benzoxazole acts as an acceptor, carbazole acts as a donor, and hexahydrophthalimido (HP, with a large intramolecular torsion angle and spatial distortion characteristics) acts as a bulky modified end-group with weak electron-withdrawing effects. Both BPCP and BPCPCHY exhibit HLCT characteristics and emit near ultraviolet in toluene at 404 and 399 nm. Compared to the BPCP, the BPCPCHY solid shows much better thermal stability (Tg, 187 vs 110 °C), higher oscillator strengths of the S1-to-S0 transition (0.5346 vs 0.4809), and faster kr (1.1 × 108 vs 7.5 × 107 s-1) and thus a much higher ΦPL in the neat film. The introduction of HP groups greatly suppresses the intra-/intermolecular charge-transfer effect and self-aggregation trends, and the BPCPCHY neat films placed in air for 3 months can still maintain an excellent amorphous morphology. The solution-processable deep-blue OLEDs utilizing BPCP and BPCPCHY achieved a CIEy of 0.06 with maximum external quantum efficiency (EQEmax) values of 7.19 and 8.53%, respectively, which are among the best results of the solution-processable deep-blue OLEDs based on the "hot exciton" mechanism. All of the above results indicate that benzoxazole is an excellent acceptor for constructing deep-blue HLCT materials, and the strategy of introducing HP as a modified end-group into an HLCT emitter provides a new perspective to develop solution-processable efficient deep-blue OLEDs with high morphological stability.

Murphyite, Pb(TeO4), the Te-Analogue of Raspite, a New Mineral from Tombstone, Arizona, USA

Abstract A new mineral species, murphyite (IMA 2021-107), ideally Pb(TeO4), has been found from the Grand Central mine, Tombstone, Arizona, USA. It occurs as bladed or prismatic crystals on top of a quartz matrix. Associated minerals include chlorargyrite, emmonsite, ottoite, stolzite, scheelite, schieffelinite, quartz, and jarosite. Individual crystals of murphyite are up to 0.20 × 0.05 × 0.05 mm in size. Twinning is common on {100}. Murphyite is colorless to very pale yellow in transmitted light, transparent with white streak and adamantine luster. It is brittle and has a Mohs hardness of ∼3½, with perfect cleavage on {100}. The calculated density is 7.579 g/cm3. Murphyite is insoluble in water or hydrochloric acid. An electron microprobe analysis yielded the empirical formula (based on 4 O apfu): (Pb0.96Fe0.03Mn0.02)Σ1.01[(Te0.61W0.38)Σ0.99O4], which can be simplified to Pb[(Te,W)O4]. Murphyite is the Te-analogue of raspite, Pb(WO4), and represents the first mineral with Te6+ substituting for W6+ over 50%. It is monoclinic with space group P21/a and unit-cell parameters a = 13.6089(3), b = 5.01750(10), c = 5.5767(2) Å, β = 107.9280(10)°, V = 362.302(17) Å3, and Z = 4. Its crystal structure consists of distorted MO6 (M = Te + W) octahedra sharing edges to form zigzag chains running parallel to [010]. These chains are linked together by PbO7 polyhedra. Compared to raspite, the substitution of W6+ by Te6+, which has a smaller ionic radius, results in a noticeable structural change: a significant decrease in MO6 octahedral angle distortion, with a concomitant increase in both MO6 octahedral volume and average Pb–O bond length. The unit-cell volume increases from 358.72(4) Å3 for raspite to 362.302(17) Å3 for murphyite. Raman spectroscopic data show that the major peak ascribable to M–O symmetrical stretching vibrations within the MO6 octahedron is centered at 870 cm−1 for raspite but at 881 cm−1 for murphyite.

Miniaturization of Rotman Lens Using Array Port Extension

This letter proposes a miniaturization design of Rotman lens using array port extension technique. The array ports of the proposed 4 × 12 Rotman lens are extended from an initial 4 × 7 Rotman lens through a port extension (PE) network to achieve a smaller equivalent lens body. The initial Rotman lens and the topology for the PE network are designed based on the analysis of phase distributions along the extended array ports when different beam ports are excited. The proposed design allows all the beam pointing angles to be consistent before and after extension at center frequency. A prototype working at X-band was fabricated. The measured results show that all beam ports are matched well, and high isolations between beam ports are achieved from 8 to 12 GHz. The Rotman lens provides a ±29° scanning range with four uniformly distributed beams at 10 GHz. The beam pointing angles remain relatively stable within 20% frequency bandwidth, with the maximum angle distortion of ±3°.

Thermal Stress Analysis and Optimization of FSW Process on UHMWPE by Using Hexagonal Tool Profile

Abstract: The use of polymeric materials has grown widely in various sectors such as packaging, building, electronic, automotive, and aerospace industries. Particularly, Ultra-High Molecular Weight Polyethylene has wide engineering applications and is used in large quantities in automotive oil pans, gears, slides, cams, bearings, fluid reservoirs, and the sports industry. Friction Stir Welding (FSW) is a solid-state process in joining thermoplastic materials. In this investigation, FSW process must be applied to join a UHMWPE plate of 8 mm thickness with specially designed hexagonal tool pin profile. The aim of this study is to examine the effect of main friction stir welding (FSW) parameters on the quality of UHMWPE plate welds. FSW machine, using a tool with a stationary shoulder and no external heating system. The welding parameters studied were the tool rotational speed which varied between 1300 and 1500 (rpm); the traverse speed which varied between 15 and 25 (mm/min), and the axial force ranging from 8 to 10 (KN). Good quality welds are achieved without using external heating, when the tool rotational speed and axial force are above a certain threshold. For high rotational speed and axial force welds have poor material mixing at the retreating side and mild voids at the nugget, tensile strength also obtained very poor. The hardness angle distortion and bead geometry also evaluated. Taguchi design optimum parameters and ANNOVA were found.

Preparation and structural characterization of 4-pyridylboron-capped iron(II) clathrochelates and their chemical transformations into hybrid metallo(IV)-phthalocyaninatoclathrochelate derivatives

Mixed boron,antimony-capped iron(II) tris-dioximate monoclathrochelates and their hybrid phthalocyaninatoclathrochelate derivatives, the molecules of which are decorated with the single N-donor 4-pyridyl group, were obtained using two different approaches, such as (i) a transmetallation (a capping group exchange) reaction of their antimony-capped macrobicyclic precursors, and (ii) the direct template condensation of the [Formula: see text] ion as a matrix. The obtained complexes were characterized using elemental analysis, 1H and [Formula: see text]C{1H} NMR, MALDI-TOF MS, and UV–vis spectra, and by the single-crystal X-ray diffraction experiments. Solution UV-vis spectra of 4-pyridyl-terminated iron(II) phthalocyaninatoclathrochelates can be described as a superposition of the spectrum of its metallocomplex precursor MIVPc and that of the iron(II)-encapsulating semiclathrochelate fragment. As follows from the X-ray diffraction data for the hybrid hafnium(IV)-capped tris-dimethylglyoximate pthalocyaninatoclathrochelate and its macrobicyclic boron,antimony-capped precursor, their [Formula: see text]-coordination polyhedra possess the geometry close to intermediate between a trigonal prism (TP) and a trigonal antiprism with the distortion angles [Formula: see text] of 20–30∘. Due to a non-equivalence of their capping fragments, it can be also described as a distorted truncated trigonal pyramid. [Formula: see text]-coordination polyhedron in the hybrid complex possesses the geometry of a capped TP. 4-Pyridylboron-capped pthalocyaninatoclathrochelates are proposed as prospective monodentate N-donor 3D-ligands for the design of various clathrochelate-based coordination assemblies, polytopic and polynuclear systems.

Time-inversion technique based correction of complex radome radiation beam distortion

In the electromagnetic wave radiated by radome, there often occur pointing angle deviation, beam distortion and other phenomena, due to the complex electromagnetic medium composition, special contour and complex working environments. For conventional optimization methods, harsh and complex situations increase its workload, especially in the case that the specific location parameter information is unknown. In this paper, a method with time-inversion technique for correcting the radiation beam distortion of the complex radome is proposed. With the time-inversionl method, the concrete parameters of different positions for the radome and the surrounding environment information are not necessary to be determined in advance. The derivation shows that the environmental information is eliminated adaptively by the conjugate convolution operation, and it is proved by numerical operation that the signal of maximum radiation gain in target angle is time-inversion signal. Then based on the adaptive focusing properties of time-inversion electromagnetic waves, a top wedge radome and an icing working radome are taken as the case study. The equal amplitude phase shifting serves as the control group to highlight the advantages of time-reversal. In the end, the results show that the radiation beam pointing error can be reduced from ±10° to ±0.9° within ±45° scanning range for the top wedge radome in C-band. And the annihilated main beam can be converged again for the radome in the icing state. In addition, all the improvements are in a broadband range, and the robustness of the entire radome system is enhanced by increasing target angle energy caused by the increasing the directionality of the array radiation and the narrowing the 3 dB beamwidth. This paper provides an effective method of analyzing the complex radomes and radio wave propagations in complex media.

Algorithmic Design of Geometric Data for Molecular Potential Energy Surfaces

A code MolecGeom, based on algorithms for stepwise distortions of bond lengths, bond angles and dihedral angles of polyatomic molecules, is presented. Potential energy surfaces (PESs) are curated in terms of the energy for each molecular geometry. PESs based on the Born–Oppenheimer approximation, by which the atomic nuclei within a molecule are assumed stationary with respect to the motion of its electrons, are calculated. Applications requiring PESs involve the effects of nuclear motion on molecular properties. These include determining equilibrium geometries corresponding to stationary and saddle point energies, calculating reaction rates and predicting vibrational spectra. This multi-objective study focuses on the development of a new method for the calculation of PESs and the analysis of the molecular geometry components in terms of incremental changes that provide comprehensive sampling while preserving the precision of PES points. MolecGeom is applied to generate geometric data to calculate PESs for theoretical calculations of vibrational-rotational spectra of water and formaldehyde. An ab initio PES comprising 525 and 2160 intramolecular nuclear configurations results in vibrational frequencies in agreement with experiment, having errors less than 0.08% and 0.8%, respectively. Vinyl alcohol, with a total of 14 internal coordinates, generates a PES of 1458 unique geometries. Ascorbic acid, with 54 internal coordinates, generates a 1,899,776 point PES.