Calculation of the position of spectral lines in the intermediate coupling approximation taking into account the interaction of configurations

When modeling experimental spectra, special attention is paid to the accuracy of the position of spectral lines, which in many-electron ions depends not only on the spin-orbital and electrostatic interaction, but also on the interaction of configurations. In order to improve the THERMOS complex on the basis of an intermediate-type bond, a module was developed that uses the Ritz method to calculate the splitting of ion levels due to the spin-orbit interaction, taking into account the interaction of configurations. Comparisons of the results obtained for lithium and iron plasma are made.

Direct observation and catalytic role of mediator atom in 2D materials

The structural transformations of graphene defects have been extensively researched through aberration-corrected transmission electron microscopy (AC-TEM) and theoretical calculations. For a long time, a core concept in understanding the structural evolution of graphene defects has been the Stone-Thrower-Wales (STW)–type bond rotation. In this study, we show that undercoordinated atoms induce bond formation and breaking, with much lower energy barriers than the STW-type bond rotation. We refer to them as mediator atoms due to their mediating role in the breaking and forming of bonds. Here, we report the direct observation of mediator atoms in graphene defect structures using AC-TEM and annular dark-field scanning TEM (ADF-STEM) and explain their catalytic role by tight-binding molecular dynamics (TBMD) simulations and image simulations based on density functional theory (DFT) calculations. The study of mediator atoms will pave a new way for understanding not only defect transformation but also the growth mechanisms in two-dimensional materials.

Cu(i) complex bearing a PNP-pincer-type phosphaalkene ligand with a bulky fused-ring Eind group: properties and applications to FLP-type bond activation and catalytic CO2 reduction

A highly Lewis acidic Cu(i) complex bearing a PNP-pincer-type phosphaalkene ligand with bulky fused-ring Eind groups activates hydrogen and phenylacetylene in an FLP-type manner, and catalyzes the hydrogenation and hydrosilylation of CO2.

On the effect of Ga and In substitutions in the Ca11Bi10and Yb11Bi10bismuthides crystallizing in the tetragonal Ho11Ge10structure type

The Ga- and In-substituted bismuthides Ca11GaxBi10–x, Ca11InxBi10–x, Yb11GaxBi10–x, and Yb11InxBi10–x(x< 2) can be readily synthesized employing molten Ga or In metals as fluxes. They crystallize in the tetragonal space groupI4/mmmand adopt the Ho11Ge10structure type (Pearson codetI84; Wyckoff sequencen2m j h2e2d). The structural response to the substitution of Bi with smaller and electron-poorer In or Ga has been studied by single-crystal X-ray diffraction methods for the case of Ca11InxBi10–x[x= 1.73 (2); octabismuth undecacalcium diindium]. The refinements show that the In atoms substitute Bi only at the 8hsite. The refined interatomic distances show an unconventional – for this structure type – bond-length distribution within the anionic sublattice. The latter can be viewed as consisting of isolated Bi3−anions and [In4Bi820−] clusters for the idealized Ca11In2Bi8model. Formal electron counting and first-principle calculations show that the peculiar bonding in this compound drives the system toward an electron-precise state, thereby stabilizing the observed bond-length pattern.

One-pot synthesis of ultrastable pentanuclear alkylzinc complexes

The first ever reported organometallic compounds featuring a Kuratowski-type bond topology were found to be unexpectedly chemically and thermally stable.

The Influence of Impressed Current on Residual Bond Strength of Corroded Structure

An experimental work was carried out to study the influence of impressed current on residual bond strength of corroded specimens. In accelerated corrosion process, two different current densities 0.08 mA/cm2 and 0.4 mA/cm2 were used which identified as ‘slow’ and ‘fast’ current. Beam end type bond specimens reinforced with 10 mm and 16 mm bar diameter were prepared for the bond test. Stirrups were provided along the main bar. Corrosion level of the main reinforcement was limited to 8% theoretical section loss. Other parameter such as the location of the test bar (corner and centre location) was also considered. The results indicate a significant influence of impressed current on the crack width with the ‘fast’ current tended to have wider crack than the ‘slow’ current. The influence on bond strength and other related parameters are being discussed.

Coordination complexes of thiazyl rings — Synthesis, structure, and density functional theory (DFT) computational analysis of CpCr(CO)x (x = 2, 3) complexes of fluorinated and nonfluorinated 1λ3-1,2,4,6-thiatriazinyls with differing Cr–S bond orders

The reaction of [3,5-Ph2-C2N3S]2 with [CpCr(CO)3]2 in toluene at room temperature forms an adduct via a Cr–S bond, formulated as CpCr(CO)3SN3C2Ph2, which has fitting NMR, IR, and combustion analysis data. The structure was determined by a single-crystal X-ray structure diffraction study (P21/n, a = 8.4611(17) Å, b = 20.509(4) Å, c = 11.757(2) Å, β = 104.453(7)°). The Cr–S bond length of 2.4908(11) Å corresponds to a bond order of 1.0 from >90 values for CpCr(CO)x or Cp*Cr(CO)x moieties (x = 2, 3) bonded to S, which are used to establish a Pauling-type bond order scale specific to this class of compounds. Similar reactions of fluorinated thiatriazinyls derived from [3-Ph-5-CF3-C2N3S]2 or [4-MeOC6H4-5-CF3-C2N3S]2 are accompanied by the loss of CO to produce CpCr(CO)2SN3C2PhCF3 (P1, a = 8.0929(8) Å, b = 10.3160(10) Å, c = 11.2405(11) Å, α = 70.032(2)°, β = 72.076(2)°, γ = 82.375(2)°) and CpCr(CO)2SN3(CCF3)(C6H4OCH3) (P21/c, a = 8.1311(7) Å, b = 24.284(2) Å, c = 9.1025(8) Å, β = 97.218(2)°), also fully characterized by spectroscopy and crystallography. Their measured Cr–S bond lengths, 2.2987(14) and 2.2965(11) Å, correspond to bond orders of 1.5. (U/R)B3PW91/6-311+G(2df,2p)//B3PW91/6-31G(2d,p) hybrid density functional theory (DFT) calculations show that the tricarbonyl complex has an unusual σ bond. However, the dicarbonyl complexes of the fluorinated thiatriazinyls are π bonded.

Bond Properties of Ceramic Concrete Reinforced by Bamboo Bar

Bond properties of ceramic concrete reinforced by bamboo bar were investigated based on pull-out tests. The influences of strength grade of ceramic concrete, material type, bond length, side length and notch spacing of bamboo bar on the bond strength between the bamboo bars and ceramic concrete were studied. The results show that the bond failure mode of ceramic concrete reinforced by bamboo bar without notch is majorly pulling-out failure, however, ceramic concrete reinforced by restructured bamboo (RB) bar with notch appears shear failure mode. The ultimate bond strength of ceramic concrete reinforced by RB bars is higher than that of ceramic concrete reinforced by laminated bamboo (LB) bar, which is close to that of ceramic concrete reinforced by plastic bars,but lower than that of ceramic concrete reinforced by steel bars under the same condition. When the notch spacing is 15 mm, the bond strength of ceramic concrete reinforced by RB bars is the highest. The conclusions can be usable for the the constitutive relationship of ceramic bamboo-reinforced concrete.

Comparative Performance of a Thermal Barrier Coating System Utilizing Platinum Aluminide Bond Coat on Alloys CMSX-4® and MAR M® 002DS

It is known that the relative performance of thermal barrier coatings is largely dependent upon the oxidation properties of the bond coat utilized in the system. Also, the oxidation properties of diffusion-type bond coats (aluminides and their modifications) are functions of the superalloy substrate used in blade applications. Therefore, the performance of a given coating system utilizing a diffusion-type bond coat can significantly vary from one superalloy to another. Toward the objective of developing coating systems with more universal applicability, it is essential to understand the mechanisms by which the superalloy substrate can influence the coating performance. In this study, we examined the relative performance of yttria-stabilized zirconia/platinum aluminide coating system on alloys CMSX-4 and MAR M 002DS representing single-crystal and directionally-solidified alloy systems respectively using thermal exposure tests at 1150 °C with a 24-h cycling period to room temperature. Changes in coating microstructure were characterized by various electron-optical techniques. Experiment showed that the coating system on alloy MAR M 002DS had outperformed that on alloy CMSX-4, which could be related to the high thermal stability of the bond coat on alloy MAR M 002DS. From a detailed microstructural characterization, this difference in behavior could be explained at least partially in terms of variation in chemical composition of the two alloys, which was also reflected on the exact failure mechanism of the coating system.

PROBING THE INTERPLAY BETWEEN MULTIPLICITY AND IONICITY OF THE CHEMICAL BOND

A new bond multiplicity measure based on the Wiberg-type bond covalency index and the atomic charge from population analysis is presented. Heuristically derived formulas allow one to evaluate the character of the chemical bond, especially its ionicity degree. Numerical results at RHF/ROHF theory level demonstrate that full multiplicities of typical chemical bonds are close to formal orders and their basis set dependence is inconsiderable, especially for highly polarized chemical bonds.