Search

The theoretical study of the use of cyano acid derivatives as electron acceptor groups in pelargonidin as a dye compound in sensitized solar cells (DSSC) was successfully carried out. Theoretical study was carried out with the purpose to determine the effect modification of the addition of cyanoacrylic benzothiadiazole, cyanoacrylate, cyanovinyl, and cyanocynamic as electron acceptors to the characteristics of pelargonidin as dye DSSC. The effect of modification is based on the parameters of bond length, spectra, molecular electron density, light harvesting efficiency (LHE), (VRP), and HOMO-LUMO energy. The molecular structure created using the Avogadro program, then optimized by DFT/TDDFT method using a base set 6.311G *. Based on the results of research on pelargonidin-benzothiadiazole cyanoacrylate is a better modification when compared with pelargonidin without modification or pelargonidin modified with other cyano acids. This modification is better modification based on parameters molecular electron density, HOMO-LUMO energy, (VRP), bond lengths, and spectra. Pelargonidin-benzothiadiazole cyanoacrylic electron density in LUMO conditions centred in benzothiadiazole cyanoacrylic, HOMO and LUMO energy of dye is -4.97856 eV & -2,56731 eV, VRP value 0.439, bond lengths 1.936 Å, and spectra at wavelength 393.14 nm & 377.09 nm. Based on the light harvesting efficiency (LHE), pelargonidin without modification is the best modification with an LHE value 0.820.

Fiber Bragg grating (FBG) based structural health monitoring applications are used in various engineering types of damage prediction and detection analysis. FBG can serve as an effective sensor for data monitoring applications as they are more robust in harsh environmental conditions and can be embedded directly into the structure. The paper aims to study the effect of the guided wave (GW) relative magnitude based on the bond and bond length with different piezoelectric lead zirconate transducer (PZT actuator) connections. The paper compares the signal amplitudes between the directly bonded and remotely bonded FBG in the structure. A parametric study was also conducted based on signal attenuation to show the changes in the bond lengths affecting the GW. The study is conducted on the subsystem-level aluminum structure. The bond length wave attenuation-based studies were done by applying glue at various distances from the FBG sensor and glue of various spread lengths to facilitate the concept of remote and direct bonding configurations. The paper tends to predict Lamb wave modes based on the arrival time and check effective bonding type in producing quality signal amplitude with different PZT connections.

[Display omitted] The crystal structure of the new iodobismuthate (PyPy) 2 (PyPyH) 2 Bi 6 I 26 was found to consist of unusual hexanuclear [Bi 6 I 26 ]6− anions containing the linear I 4 2− unit, and the experimental Bi–I bond lengths in this anion were used to obtain the relationship between bond length and bond energy. A statistical analysis of 229 crystal structures of iodobismuthates, based on the quantum chemically estimated strength of Bi–I bonds, revealed that the total energy of the Bi3+ polyhedron remains virtually constant at 64 ± 2 kcal mol−1, regardless of its geometry within this family of materials. Thus, the polyhedron geometry flexibly adapts to the relatively weak interactions between iodobismuthate anions and embedded cations. [ABSTRACT FROM AUTHOR]

In this work, we have presented a correlation between the bond length and electronic properties of Cu2XYS4 (X = Zn, Cd and Y = Sn, Pb) from the first-principles calculation. Lattice parameters, bond length, electronic structure and partial density of state are determined by using density functional theory based on generalized gradient approximation. Further, we have calculated the thermoelectric properties in relation to electronic band energy from the Boltzmann transport theory. The room temperature (300 K) optimum value of electrical conductivity is found to be 5 × 105 S m for Cu2CdPbS4, Seebeck coefficient is 320 µV/K for Cu2ZnSnS4, thermal conductivity is 0.12 W/m K for Cu2ZnSnS4, and the optimal figure of merit is 0.68 for Cu2ZnSnS4. This study shows that the stronger interaction between (Zn, Sn) and S atoms leads to the combination of heavy and light bands in the valence region which improves the thermoelectric performance. It is concluded that the Cu2ZnSnS4 and Cu2CdSnS4 compounds can be considered as potential materials for thermoelectric applications due to their strong bonding interactions. [ABSTRACT FROM AUTHOR]

In the present work, we have calculated the structural and mechanical properties of II–VI and III–V tetrahedral semiconductors using some empirical relations. The calculated properties are then correlated with the optical energy gap of respective semiconductors. We carried out a comparative analysis between the predictions obtained from different empirical relations. An exponential relationship is proposed to obtain plasmon energy of binary tetrahedral semiconductors directly from their energy gap. The plasmon energy have been correlated with some of the semiconductor properties. The predicted values of the structural and elastic properties of the semiconductors from a recently proposed Tripathy relation are found to be compatible with those from many other established empirical formulae. [ABSTRACT FROM AUTHOR]

In the recently introduced phenomenological diatomic molecular model imagining the clusters as certain constructions of pair interatomic chemical bonds, there are estimated specific (per atom) binding energies of small all-boron planar clusters Bn, n = 1–15, in neutral single-anionic and single-cationic charge states. The theoretically obtained hierarchy of their relative stability/formation probability correlates not only with results of previous calculations, but also with available experimental mass-spectra of boron planar clusters generated in process of evaporation/ablation of boron-rich materials. Some overestimation in binding energies that are characteristic of the diatomic approach could be related to differences in approximations made during previous calculations, as well as measurement errors of these energies. According to the diatomic molecular model, equilibrium binding energies per B atom and B–B bond lengths are expected within ranges 0.37–6.26 eV and 1.58–1.65 Å, respectively.

Boron carbide comprises of polymorphs that differ in crystallographic arrangement and stoichiometry. Consequently, specimens extracted from the same batch can exhibit variability in mechanical properties depending on the constituent mixture of polymorphs. In this work, density functional theory simulations and estimates from three models (bond resistance model, bond strength model, and electronegativity model) are utilized to (i) investigate the influence of polymorphism and stoichiometry on the intrinsic hardness of boron carbide, (ii) reveal the sensitivity of the estimates to the model used, and (iii) test their conformance to experimental data. The study finds intrinsic hardness of boron carbide to be primarily a function of stoichiometry, with polymorphism having a lower influence. Furthermore, hardness estimates are shown to exhibit substantial sensitivity to the model used, differing by as much as 9 GPa for the same polymorph. Thus, the search for new superhard materials should be guided by more than just one model. Our analysis finds bond resistance model to offer the best conformance to experimental data, indicating that bond length is a much stronger influencer of intrinsic hardness in covalent crystals than coordination numbers and electronegativities of bonding atoms. [ABSTRACT FROM AUTHOR]

Sr0.6Ca0.4LaAlO4 ceramic was fabricated via solid-state sintering route and the effect of TiO2 addition on its microwave dielectric properties was investigated. Sr0.6Ca0.4LaAlO4 formed as the major phase along with LaAlO3 as a minor phase at 1400 °C. However, the concentration of LaAlO3 phase increased with increase in the sintering temperature and it became a major phase at 1475 °C. Maximum density was obtained for the composition with x = 0 (i.e., Sr0.6Ca0.4LaAlO4 ceramics) sintered at 1450 °C for 4 h. The TiO2 addition lowered the maximum densification temperature to 1400 °C from 1450 °C. The microwave dielectric properties varied linearly with increasing the volume fraction of TiO2 (x value). Relative permittivity (εr) increased from 20.7 to 31.1, Qufo decreased from 95,250 to 65,000 GHz, and τf was tuned through zero and increased from − 29.5 to + 25.4 ppm/°C with increase in the x value from 0 to 0.2. In the present study, εr ≈ 24.8, Qufo ≈ 83,500 GHz, and a near-zero τf ≈ − 2.5 ppm/°C was obtained for the composition with 10wt% addition of TiO2. [ABSTRACT FROM AUTHOR]

In this study, the phenotype of Fe‐doped Nano‐C2N monolayer (C2N monolayer) was analysed based on the Perdew‐Burke‐Ernzerh‐solids (PBEsol) functional of First‐principles. The results indicate that the length of Fe‐C bonds is significantly higher than the C‐N bond. For Fe atom doped, the band gap of C2N monolayer system is reduced from 1.811 to 0.384 ev, which increases the activity of electron hopping. Moreover, at Fe‐doped C2N positions, the partial density of states (PDOS) of the C2N monolayer is well overlapped. That indicates that there has a strong interaction between the Fe atom and the C2N monolayer. Furthermore, after doping with Fe atom, C2N monolayer shows better light absorption ability in the ultraviolet and infrared regions. The corresponding conduction band minima (CBM) values in the Fe‐doped C2N monolayer system are lower than that of the pristine C2N monolayer system. In particular, it was lower than the O2/O2•− redox potential, which show that the electrons located in the conduction band have the potential to convert the oxygen molecules into superoxide radicals. Our findings suggest that Fe‐doped C2N monolayer can be a promising material for the novel photocatalytic degradation materials. [ABSTRACT FROM AUTHOR]

This work deals with the optimization of process parameters for rehabilitation of the pipe through-wall hole defects using adhesive bonding. Epoxy-based nonstructural adhesive (NSA) and structural adhesive (SA) combination, precure temperature, bond length, and surface preparation were considered as the parameters. The optimization of parameters directly on pipes is an expensive and time-consuming process. Hence, stainless steel and carbon fiber-reinforced polymer (SS-CFRP) composite single-strap joint was considered. The equivalent loads that were acting during the hydrostatic pressure test were applied to the SS-CFRP joint and its parametric effect on bond strength was studied. The stress distribution along the adhesive layer length has been derived analytically. The surface roughness of prebond surfaces was measured using a 3-D microscope. The quality of the adhesive bond was evaluated using nondestructive testing (digital radiography). The damaged pipe was rehabilitated with optimized parameters and its hydrostatic pressure resistance was tested according to ISO/TS 24817 standards. From the results, it is observed that the rehabilitated pipe with optimized parameters was able to sustain a maximum of 79% of its allowable pressure. [ABSTRACT FROM AUTHOR]

Bottleneck size is the minimum Li+ migration channel of Li7La3Zr2O12 (LLZO) and it greatly influences the Li+ conductivity. Doping different elements on the Zr site of LLZO can adjust the bottleneck size and improve the Li+ conductivity. However, the regulation mechanism is not clear. In this work, Li6.4La3Zr1.4M0.6O12 (M = Sb, Ta, Nb) has been prepared and the bottleneck size has been adjusted by doping different pentavalent ions. The results manifest that the cell parameter and bottleneck size decrease with the rise of the radius of doped pentavalent ions. This is because larger pentavalent ion leads to larger bond length of M–O, and weaker covalent component between M5+ and O2‐, corresponding, the formal charge on the M5+ become larger, and the bond length of La–O slightly decreases due to the coulomb repulsion between La3+ and M5+ increase. While, the activation energy drop firstly and then rise with the rise of bottleneck size because of the migration of Li+ not only relate to the size of the migration channel but also to the strength of M–O covalent bonding. The bottleneck size and bond length of M–O synergistically affect the migration of Li+. [ABSTRACT FROM AUTHOR]

Based on molecular dynamics (MD) simulation, the binding energy, cohesive energy density (CED), bond length, and mechanical parameters were calculated for 2,6-diamino-3,5-dinitropyrazine-l-oxide (LLM-105) crystal, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) crystal, and their co-crystals under different temperatures. Three LLM-105/HMX patterns were constructed to investigate the influence of component proportion on structures and properties of co-crystals, in which the mole ratios of LLM-105 and HMX are 1:1, 1:2, and 2:1. The effect of temperature and components on the stability and sensitivity were investigated as well. The results show that the binding energies, CED and mechanical parameters of all the co-crystals, decrease when the temperature increases from 248 to 398 K, while their maximum N–NO2 bond length (Lmax) increases with rising temperature, indicating that the sensitivities increase and stabilities decrease when temperature rises. At all temperatures, co-crystals exhibit larger CED and shorter bond length than that of single explosive, demonstrating that they are more stable and less sensitive than single crystal, where the stability of co-crystals was ordered as 2:1>1:1>1:2. Moreover, the bulk modulus (K) and shear modulus (G) of co-crystals are lower than that of HMX, conversely, the Cauchy pressure and K/G are higher than that of HMX, implying co-crystals have better ductility. Finally, the 2:1 ratio of LLM-105/HMX co-crystal was identified as the excellent one, owning to the highest binding energy, highest CED, shortest Lmax, and greatest ductility. [ABSTRACT FROM AUTHOR]

Ｉｎ ＣａＯ-Ａｌ２Ｏ３-ＣａＦ２ ｔｅｒｎａｒｙ ｓｌａｇ ｓｙｓｔｅｍ, ｔｈｅ ｖａｒｉａｔｉｏｎｓ ｏｆ ｔｈｅ ｍｅｌｔ ｓｔｒｕｃｔｕｒｅｓ ｉｎｃｌｕｄｉｎｇ ｔｈｅ ｓｈｏｒｔ-ｒａｎｇｅ ａｎｄ ｍｅｄｉｕｍ-ｒａｎｇｅ ｓｔｒｕｃｔｕｒｅ, ａｎｄ ｂｏｎｄ-ａｎｇｌｅ ｃｈａｎｇｅ ｏｆ ｔｈｅ ｓｌａｇ ｗｉｔｈ ｄｉｆｆｅｒｅｎｔ ＣａＦ２ ｃｏｎｔｅｎｔ ｗｅｒｅ ｓｔｕｄｉｅｄ ｕｓｉｎｇ ｍｏｌｅｃｕｌａｒ ｄｙｎａｍｉｃｓ(ＭＤ)ｍｅｔｈｏｄ. Ｔｈｅ ｒｅｓｕｌｔｓ ｓｈｏｗｅｄ ｔｈａｔ ｔｈｅ ａｖｅｒａｇｅ ｂｏｎｄ ｌｅｎｇｔｈｓ ｏｆ Ｃａ—Ｆ, Ａｌ—Ｆ, Ｃａ—Ｏ ａｎｄ Ａｌ—Ｏ ａｒｅ ０. ２３４ ５, ０. １８９ ５, ０. ２３２ ５ ａｎｄ ０. １７４ ５ ｎｍ,ｒｅｓｐｅｃｔｉｖｅｌｙ. Ｗｉｔｈ ｔｈｅ ａｄｄｉｔｉｏｎ ｏｆ ＣａＦ２, ｔｈｅｒｅ ｉｓ ａ ｄｙｎａｍｉｃ ｅｑｕｉｌｉｂｒｉｕｍ ｂｅｔｗｅｅｎ Ｃａ２ ＋ ａｎｄ ｔｈｅ ｃｏｏｒｄｉｎａｔｉｏｎ ａｎｉｏｎｓ(Ｏ２-ａｎｄ Ｆ-), ａｎｄ ｔｈｅ ｔｏｔａｌ ｃｏｏｒｄｉｎａｔｉｏｎ ｎｕｍｂｅｒ(ＣＮ)ｉｓ ｍａｉｎｔａｉｎｅｄ ｂｅｔｗｅｅｎ ６ ａｎｄ ７. Ｔｈｅ Ａｌ—Ｏ ｔｅｔｒａｈｅｄｒａｌ ｓｔｒｕｃｔｕｒｅ ｉｎ ｔｈｅ ｓｙｓｔｅｍ ｃａｎ ｂｅ ｔｒａｎｓｆｏｒｍｅｄ ｆｒｏｍ ｔｈｅ ｃｏｍｐｌｅｘ(Ｑ４ ａｎｄ Ｑ３)ｔｏ ｓｉｍｐｌｅ(Ｑ２ ａｎｄ Ｑ１)ｓｔｒｕｃｔｕｒｅ ａｎｄ ｆｒｏｍ ｔｈｅ Ａｌ—Ｏ ｔｅｔｒａｈｅｄｒａｌ[ＡｌＯ４ ]５ － ｔｏ [ＡｌＯ３Ｆ ]４-ｓｔｒｕｃｔｕｒｅ, ｒｅｓｕｌｔｅｄ ｔｏ ｄｅｐｏｌｙｍｅｒｉｚｅ ｔｈｅ ｎｅｔｗｏｒｋ ｓｔｒｕｃｔｕｒｅ ｏｆ ｔｈｅ ｍｅｌｔ. Ｔｈｅｓｅ ｏｂｓｅｒｖａｔｉｏｎｓ ｆｒｏｍ ａｔｏｍｉｃ ｓｃａｌｅ ｗｅｌｌ ｅｘｐｌａｉｎ ｔｈａｔ ｔｈｅ ａｄｄｉｔｉｏｎ ｏｆ ＣａＦ２ ｃａｎ ｉｍｐｒｏｖｅ ｔｈｅ ｆｌｕｉｄｉｔｙ ｏｆ ＣａＯ-Ａｌ２Ｏ３-ＣａＦ２ ｓｌａｇ. Ｔｈｅ ｂｏｎｄ ａｎｇｌｅ ａｎａｌｙｓｉｓ ｉｎｄｉｃａｔｅｓ ｔｈａｔ ｔｈｅ Ｆ － ｉｎ ｔｈｅ ｓｙｓｔｅｍ ｉｓ ｍｏｒｅ ｌｉｋｅｌｙ ｔｏ ｒｅｐｌａｃｅ ｔｈｅ ｏｒｉｇｉｎａｌ Ｏ２-ｐｏｓｉｔｉｏｎ ａｎｄ ｔｈｅ ｎｅｔｗｏｒｋ ｓｔｒｕｃｔｕｒｅ ｗｉｔｈ ｔｈｅ Ａｌ３ ＋ ｃｏｒｅ ｈａｓ ｓｔｉｌｌ ｂｅ ａ ｔｅｔｒａｈｅｄｒａｌ ｓｔｒｕｃｔｕｒｅ, ｗｈｉｃｈ ｄｏｅｓ ｎｏｔ ｃａｕｓｅ ａ ｌａｒｇｅ-ｓｃａｌｅ ａｔｏｍｉｃ ｒｅａｒｒａｎｇｅｍｅｎｔ. [ABSTRACT FROM AUTHOR]

A series of Cd x Co 1-x Cr 0.5 Fe 1.5 O 4 ferrite sample with (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) have been prepared by powder metallurgy method. The structural, morphological, magnetic and optical properties of prepared samples have been characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), Vibrating sample magnetometer (VSM) and UV–visible spectroscopy respectively. The distribution of cation in site-A, site-B and lattice parameters have been deduced by X-ray-diffraction-data analysis. The lattice constant (A°) was found to increase with increment of Cd2+ contents in the spinel ferrites. The hysteresis curves undoubtedly designate the soft nature of the prepared ferrite samples. The saturation magnetization (Ms) decreases with increasing Cd contents3w, this result is interrelated to the magnetic moments of Cd2+ ions. The Y–K angles decrease with addition of cadmium content and this decrement in the Y–K angles proposes the lessening of triangular spin arrangements on octahedral sites which consequently lead to decrease the A-B interaction. The band gap energy is showing the increasing trend which is due to decreasing crystallite size. [ABSTRACT FROM AUTHOR]

In this paper, the structural and electronic properties of a CN fullerene with N = 20, 60, 80, 180, and 240 have been investigated using a sp3 tight-binding model. The analytical expressions for the calculation of the total number of carbon atoms, hexagons, pentagons, and bonds found within the geometrical structure of a CN fullerene have been developed and verified using the simulation, therefore proving the validation of both the simulation and analytical results. The simulation results show that the total number of carbon atoms within fullerene is equal to the value of N and the total number of hexagons, pentagons, and bonds within the structure of a fullerene increases with the increase in the value of N. Further, the electronic properties of these fullerenes have been identified with the help of their energy level diagrams obtained using the simulation. It has been observed that the C20 and C80 fullerenes are metallic because of their zero band gaps while the C60 fullerene is an insulator with a very wide band gap of 5 eV whereas the C180 and C240 fullerenes are semiconducting with band gaps of 1.43 eV and 1.05 eV, respectively. Finally, it has been observed from these studies that the metallic fullerenes are best suited for interconnects and the semiconducting fullerenes are bested suited as a channel material for designing high-performance nanoelectronic devices. [ABSTRACT FROM AUTHOR]

Spinel ferrite nanoparticles Nickel zinc ferrite (Ni 1-x Zn x Fe 2 O 4 (x = 0.5)) and magnesium ferrite (MgFe 2 O 4) are synthesized by sol-gel auto-combustion and annealed at 1150 °C and 1200 °C respectively. X-ray diffraction (XRD) confirms the presence of a single-phase cubic spinel structure. Lattice parameters crystallite size and density of ferrites are calculated from the XRD data. Surface morphology of the spinel ferrites is studied using Field Emission Scanning Electron Microscopy (FE-SEM). Optical properties such as bandgap, refractive index, extinction coefficient, dielectric constant, and dielectric loss are calculated using UV–Visible spectroscopy. Two absorption bands for each are identified by Fourier Transform Infrared Spectroscopy (FT-IR) peaks, with the lower frequency (400Hz) corresponding to the metal-oxide bond vibrations at the octahedral site and the higher frequency (600Hz) corresponding to the metal-oxide bond vibrations at the tetrahedral sites of the spinel lattice. Magnetic properties are analysed using Vibrating Sample Magnetometer. [Display omitted] • Band gap, refractive index, extinction coefficient, dielectric constant and dielectric loss are determined from UV data. • Study of elastic constants from FTIR spectroscopy. • Bond lengths and bond angles of materials are calculated using lattice parameter. • Magnetization, coercivity and retentivity is found from VSM data. [ABSTRACT FROM AUTHOR]

It is very important to understand the structure-performance relationship of metal catalysts by adjusting the microstructure of catalysts at the atomic scale. The atomic distance has an essential influence on the composition of the environment of active metal atom, which is a key factor for the design of targeted catalysts with desired function. In this review, we discuss and summarize strategies for changing the atomic distance from three aspects and relate their effects on the reactivity of catalysts. First, the effects of regulating bond length between metal and coordination atom at one single-atom site on the catalytic performance are introduced. The bond lengths are affected by the strain effect of the support and high-shell doping and can evolve during the reaction. Next, the influence of the distance between single-atom sites on the catalytic performance is discussed. Due to the space matching of adsorption and electron transport, the catalytic performance can be adjusted with the shortening of site distance. In addition, the effect of the arrangement spacing of the surface metal active atoms on the catalytic performance of metal nanocatalysts is studied. Finally, a comprehensive summary and outlook of the relationship between atomic distance and catalytic performance is given., (© 2023 Wiley-VCH GmbH.)

New expressions for the energy and the length of interatomic bonds depending on atomic number, bond order, and angular momentum are derived within the theory of generalized charges, which is an asymptotic approximation for interatomic forces in the quantum-statistical model of a multicomponent electron gas. In particular, expressions for bond energies and bond lengths in hydrides are derived as functions of atomic numbers. As a consequence of the developed theory, hydrogen bonding is viewed as a one-electron covalent bonding, which is used to derive corresponding quantitative relations. The energy of hydrogen bonding cannot be lower than some specific value determined by the charge of the bonded atom. The region of existence of hydrogen bonding is established. The boundaries of the region are determined by the classes of substances distinguished by their ability to form hydrogen bonding. Quantitative estimations are used to explain the ability or inability of substances containing electronegative atoms to dissolve in water. [ABSTRACT FROM AUTHOR]

Lead doped nickel ferrite Ni1-xPbxFe2O4 (x = 0.0 to 1.0) nanoparticles have been successfully prepared via co-precipitation method. The structural and magnetic properties investigated by XRD, FTIR, TEM, and VSM. XRD confirmed the formation of cubic spinel structure. Particle size evaluated using Debye Scherrer formula was found to be in the range 30–50 nm. In FTIR spectra, two fundamental absorption bands at around 620 cm−1 and 500 cm−1 observed whereas the characteristic of M-O vibrations. TEM image shows that the particles are agglomerated and spherical shape. Magnetic parameters of coercivity, remenence, squareness ratio, and anisotropy constant values decrease. [ABSTRACT FROM AUTHOR]

The insertion of different elements in the cobalt ferrite spinel structure can significantly change the structural and magnetic characteristics of cobalt ferrite bulks and thin films. Pulsed Laser Deposition (PLD) is an extensively used method which permits the growth of thin films with complex chemical formula. The thin film of Co1-xAgxCr 0.5Fe 1.5O 4 (x=0, 0.2, 0.4, 0.6, 0.8, 1.0) have been grown on single crystal p-type silicon Si(100) substrate by pulsed laser deposition technique using Nd-YAG laser. The structural properties of the thin films have been carried out by X-ray diffractrometer (XRD). The structural analyses confirm the epitaxial growth of (220) plane spinel ferrites with cubic symmetry. Surface morpholgy is deeply studied using Atomic Force Microscopy (AFM). The magnetic properties of deposite thin films have been measured by Vibrating Sample Magnetometer (VSM). The optical parameters like absorption, band gap energy and thickness of the thin films have been extracted from Spectroscopy Ellipsometry (SE). [ABSTRACT FROM AUTHOR]

Microwave dielectric properties of MgTi1−x(A1/3Sb2/3)xO3 (A = Mg2+, Zn2+, 0 ≤ x ≤ 0.125) ceramics were investigated as a function of the electronegativity difference (X) between (A1/3Sb2/3)4+ ions (A = Mg2+, Zn2+) and O2− ion. A single phase with an ilmenite structure was detected for the specimens sintered at 1450°C for 4 hours in the entire range of compositions. With the substitution of (A1/3Sb2/3)4+ ions (A = Mg2+, Zn2+) at Ti4+‐sites of MgTiO3, the quality‐factor (Qf) values of the specimens increased up to x = 0.05 mol, and then decreased with the further substitution owing to the electronegativity difference (X) between the (A1/3Sb2/3)4+ ions (A = Mg2+, Zn2+) and Ti4+ ion. The specimens with (Mg1/3Sb2/3)4+ ions exhibited higher Qf values than those with (Zn1/3Sb2/3)4+ ions. These results could be attributed to the smaller electronegativity of (Mg1/3Sb2/3)4+ (1.80) than that of (Zn1/3Sb2/3)4+ (1.92). The dependences of the microwave dielectric properties on the structural characteristics of the MgTi1−x (A1/3Sb2/3)xO3 ceramics were also discussed. [ABSTRACT FROM AUTHOR]

In order to study the bond properties of BFRP Bars and insulation wall panel protective layer concrete after plastic film steaming the design method of orthogonal experiment was adopted considering the influence of three factors which was concrete strength protective layer thickness and bond length under different levels. BFRP bars concrete specimens were steamed for 8 h and then were cured in standard for 3 d and 28 d respectively and then the center pulling out experiment was tested. The change rule of bond strength with influencing factors was studied and multiple linear regression method was used to regress the bond strength of BFRP reinforced concrete specimens for 3d and 28 d respectively. The results show that the bond length is the most significant factor influencing the bond strength of specimens and the strength of concrete takes second place the thickness of protective layer is even less and the variation rule of 3 d and 28 d is consistent. The optimum combination of the bond strength was that the strength grade of concrete was C30 the concrete cover thickness was 40 mm and the bond length was 20 mm. The regression formula provides the theoretical basis for the bond strength of different concrete strength protective layer thickness and bond length of specimens in varied ages. [ABSTRACT FROM AUTHOR]

In this paper, using Fourier transform infrared (FTIR) spectroscopy, ion conductivity measurements and first-principle density functional theory (DFT) calculations, we study intermolecular interactions between three molecules (methyl tetrahydrophthalic anhydride (MeTHPA), succinonitrile (SN) plastic crystal, and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt) constituting the lithium-ion battery electrolyte. The C–O stretching band position in MeTHPA shifts to a lower frequency in the order of MeTHPA–SN < MeTHPA < MeTHPA–LiTFSI/SN < MeTHPA–LiTFSI; the average C–O bond length in MeTHPA increases in the same order, which reveals the linear correlation between the vibration frequency shift and bond length change. Furthermore, the lithium ionic conductivities of MeTHPA–LiTFSI/SN and MeTHPA–LiTFSI are consistent with this linear relationship, which confirms that the bond length, vibration frequency and lithium-ion transport are strongly influenced by molecular-level interactions. Our results provide fundamental insights valuable for the understanding of the effect of intermolecular interactions on molecular geometry and physical quantities in different electrolytes, and could be utilized to guide the design of high-performance electrolyte materials. [ABSTRACT FROM AUTHOR]

Abstract The structural origin of the negative coefficient of thermal expansion (CTE) along the c-axis in cordierite is investigated using high temperature X-ray diffraction. The evolution of the lattice parameters, bond length, covalent character, and electron density distributions are analyzed with increasing temperature. The increase of covalent character of the tetrahedral bonds in the six-membered hexagonal ring is considered as the possible origin for the negative expansion. In addition, the bridging oxygen can act as a buffer absorbing thermal energy and prevents the increase in M1-O-M2 bond. The electron density distribution indicates that the linking oxygen strongly vibrates transversely across two coordinate M1-O-M2 linkages. The CTE and pore size and distribution change drastically at near 1300 °C due to the substantial increase in cordierite phase proportion and the formation of a liquid phase. Raw materials are consumed completely at 1450 °C and the CTE decreases to 1.3 ppm K−1. [ABSTRACT FROM AUTHOR]

The fabrication of low cost and eco-friendly transparent electronics using metal oxide semiconductors is still a challenging task. In this work, transparent nanocrystalline (Bi2O3)1−x:(TiO2)x thin films were synthesized using a pulsed laser deposition technique (PLD); XRD analysis shows the films have polycrystalline structure of monoclinic Bi2O3; morphological and topographical properties were analyzed by SEM and AFM showing the films have smooth surfaces with RMS roughness (4.26–7.37 nm) with micro-and nano-spheres (2 μm to 23 nm); the optical properties were analyzed by Uv-Vis spectrometer and revealed high transmittance in the visible range; the best results were obtained at x = 0.05 where the highest crystallinity, highest transmittance (> 82%), and highest band gap (3.769 eV) were achieved; and empirical models have been proposed to estimate the band gap and Bi–O bond lengths as a function of TiO2 concentration with excellent coincidence with the experimental data. [ABSTRACT FROM AUTHOR]

Abstract The atomic structure evolution of Gd 36 Tb 20 Co 20 Al 24 high entropy metallic glass microwire from room to cryogenic temperature has been studied by in-situ high energy synchrotron X-ray diffraction. During the cooling process, the atomic volume decreases. For short-range order, the coordination numbers of all atomic pairs increase. As the temperature decreases, bond lengths of large atom-small atom and small atom-small atom pairs keep decreasing whereas that of large atom-large atom pairs unexpectedly increases continuously. The mechanism of atomic structure evolution is proposed, which might be helpful for better understanding the low temperature magnetocaloric effect of high entropy metallic glasses. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Highlights • Effect of varying bond-slip relation on the behaviour of CFRP-to-steel bonded joints under sustained load is studied. • Effect of the bond length on the bond behaviour of CFRP-to-steel joints with varying bond-slip relations. • Effect of the mechanical loading rate to thermal loading rate on the bond behaviour of CFRP-to-steel bonded joints is investigated. Abstract The mechanical properties of different adhesives at elevated temperatures can change differently due to the differences in adhesive molecular chain structure. Therefore, a profound understanding of the effect of these property changes on the bond behaviour of carbon fibre reinforced polymer (CFRP)-to-steel bonded joints is of great importance when designing bonded CFRP strengthening systems for steel structures. Existing studies on CFRP-to-steel bonded joints under monotonic loading have clearly shown that both adhesive mechanical properties and geometrical properties of the bonded joints (e.g. bond length) may significantly influence the bond strength. Existing studies on adhesive mechanical properties under elevated temperatures have shown that the variation of adhesive mechanical properties, especially fracture energy with temperature depends significantly on the adhesive type. No comprehensive study exists so far on understanding the effects of key mechanical and geometrical parameters of a CFRP-to-steel bonded joints at elevated temperatures on bond strength. This paper presents a study aimed at understanding the effects of different parameters such as temperature dependent mechanical properties of adhesive and bond length on the behaviour of CFRP-to-steel bonded joints at elevated temperatures. Results of this study showed that (1) load-displacement behaviour of the bonded joints is sensitive to temperature variations, (2) for bonded joints with sufficiently long bond length, the ultimate load depends only on the fracture energy of the final temperature, and (3) the maximum load of the bonded joints depends on the ratio between the loading and heating rates. [ABSTRACT FROM AUTHOR]

Abstract In this work, we will study the elastic and inelastic light scattering by the silicon nanocrystals (Si-nc) embedded in amorphous silicon nitride matrix. Indeed, the photons are subjected to several modifications in terms of intensity, direction and wavelength when they interact with Si-ncs. The reflectance combined with photoluminescence (PL) and Raman spectroscopy are a very sensitive tool for probing the scattering light. Results show that the observed shift of the experimental PL peaks is attributed to the Raman scattering and the PL broadening peaks to the Rayleigh scattering. A novel method allowed the determination of both the core and the surface bond lengths of Si-nc was reported. The decrease of the Raman shift observed in structures containing Si-ncs is mainly due to the Si-nc curved surface, and it reflects the presence of silicon dangling bonds at the Si-nc interfaces. [ABSTRACT FROM AUTHOR]

Abstract Fiber Reinforced Polymer (FRP) anchors are an effective method to increase the bond strength and/or ensure load path continuity between FRP materials and the concrete substrate when FRP materials are used as Externally Bonded Reinforcement (EBR) to strengthen and/or repair existing structures. While advances in developing a design methodology have been made on the fiber rupture and concrete cone failure modes for FRP anchors, the FRP-to-FRP bond behavior has received limited research attention. In an effort to develop design equations to calculate FRP-to-FRP bond capacity to be used by engineers, an extensive experimental program was undertaken to characterize the behavior of adhesively bonded FRP-to-FRP lap joints. Two force-based models to calculate the FRP-to-FRP bond capacity were proposed considering the influence of the critical bond length on lap joint behavior. A study to characterize the statistical properties of the experimental data was undertaken, and 95 and 99.87 percentile models were developed based on the statistical distribution of the experimental data set. Main conclusions inferred from the study and ideas for future work are also presented. [ABSTRACT FROM AUTHOR]

The vibrational frequencies for the fundamental modes and the low lying states of carvacrol and eugenol in gas phase have been calculated at DFT ab-initio level. The calculated vibrational frequencies of carvacrol and eugenol were further compared to assess their reactivity. It was found that eugenol is more reactive than carvacrol, which was evident from the higher frequencies of O-H stretching in carvacrol as compared to eugenol. This could be because of the presence of one of the most prominent reactive site in both the molecules. The same observation was also confirmed when we compared the bond length and ADMP calculations with DFT (B3LYP) at 6-311G(d,p) level, which is further suggestive of the higher reactivity of Eugenol over Carvacrol. Therefore Eugenol could have predominant role to cure various diseases as it is known to possess several pharmacological properties such as anaesthetic, antioxidant, antimicrobial, anti-inflammatory, anticarcinogenic, antifumigant, and antirepellent etc. [ABSTRACT FROM AUTHOR]

The prediction of the aqueous pKa of carbon acids by Quantitative Structure Property Relationship or cheminformatics-based methods is a rather arduous problem. Primarily, there are insufficient high-quality experimental data points measured in homogeneous conditions to allow for a good global model to be generated. In our computationally efficient pKa prediction method, we generate an atom-type feature vector, called a distance spectrum, from the assigned ionisation atom, and learn coefficients for those atom-types that show the impact each atom-type has on the pKa of the ionisable centre. In the current work, we augment our dataset with pKa values from a series of high performing local models derived from the Ab Initio Bond Lengths method (AIBL). We find that, in distilling the knowledge available from multiple models into one general model, the prediction error for an external test set is reduced compared to that using literature experimental data alone.

• An experimental database for bond behavior of rebar in SFRC is collated. • The effect of test methods, c / d , l / d and fiber factor on bond strength is analyzed based on extensive data. • The applicability of existed bond strength models is evaluated. • A modified bond strength model is proposed with consideration of all the parameters. The addition of steel fiber is an effective method to improve the bond behavior between reinforcement and concrete. However, a unified bond strength model for bond strength of reinforcement in steel fiber reinforced concrete (SFRC) is not available yet. In this paper, the effect of the related factors on the bond strength is first analyzed and then a modified bond strength is proposed, based on 449 test data collected from 18 bond experimental studies. The influencing factors considered include bond test methods, cover to rebar-diameter ratio (c / d), bond length to rebar diameter ratio (l / d), fiber fraction (V f), fiber slenderness (l f / d f) and rebar diameter (d). The results indicate that bond strength is greatly affected by c / d and l / d , while the effect of steel fiber is correlated with the composite fiber factor (V f ·l f / d f) and fiber distribution uniformity. In addition, the applicability of five SFRC bond strength models proposed previously is evaluated based on statistical characteristics. Current bond strength models have limited applicability and some models inappropriately neglect the effect of bond length. A modified bond strength model with improved goodness-of-fit and prediction accuracy is proposed which has good applicability to both pullout and beam bond tests. [ABSTRACT FROM AUTHOR]

In this study, laboratory pull tests of rock bolts were conducted to verify and update existing stress transfer models. The rock bolt samples in the study had different bond lengths that were fully encapsulated in cementitious grout with different water-cement ratios. The test results show that the existing models do not correctly describe the shear stress distribution on the bond length in some loading stages. Three new models were proposed for the distribution of shear stress along the bond length. The first model describes cases where the bolt sample has a bond length that is much longer than the critical bond length, the second model describes cases where the bolt sample has a bond length slightly shorter than the critical bond length, and the third model describes cases where the bolt sample has a bond length that is much shorter than the critical bond length. In these models, the bolt is fully debonded along the section between the borehole collar and a depth of approximately one bolt diameter (d b). The bolt is then partially debonded and the residual shear stress on the bolt increases with depth. In the first model, the shear stress reaches the maximum at a depth of approximately 3 d b. The shear stress then attenuates to zero at a depth of 25 d b. In the second and third models, the entire bond length is mobilized to carry load. [ABSTRACT FROM AUTHOR]

The structural, bonding, electronic, mechanical and thermal properties of ternary aluminum silicon carbides Al4SiC4 and Al4Si2C5 are investigated by first-principles calculations combined with the Debye quasi-harmonic approximation. All the calculated mechanical constants like bulk, shear and Young's modulus are in good agreement with experimental values. Both compounds show distinct anisotropic elastic properties along different crystalline directions, and the intrinsic brittleness of both compounds is also confirmed. The elastic anisotropy of both aluminum silicon carbides originates from their bonding structures. The calculated band gap is obtained as 1.12 and 1.04 eV for Al4SiC4 and Al4Si2C5 respectively. From the total electron density distribution map, the obvious covalent bonds exist between Al and C atoms. A distinct electron density deficiency sits between AlC bond along c axis among Al4SiC4, which leads to its limited tensile strength. Meanwhile, the anisotropy of acoustic velocities for both compounds is also calculated and discussed.

In this research work at The first compounds [C60- 2-(naftalin-1-ilmetil)-4,5-dihidro-1H-imidazol-C65-2X]+ (X=F,Cl,Br) were optimized. Then the calculation of natural bond orbitals was performed with the NBO technique. All calculations using Hartree- fock the 6-31G * basis set using Gaussian 98 software and in gas phase has been done. The results showed that the energy levels of molecular orbital (HOMO & LUMO) in the RF has the lowest value. C65-X has a length of the shortest bond and the bond has most power. Comparison of the dipole moments of compounds shows this trend: RF> R-Cl> R-Br. Both ratio Core / charge and the valence / charge for carbon atoms 31, 55, 65 and 63 in the RF has the highest value.