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Properly designed interfacial electric fields between CdS and Bi 2 MoO 6 can effectively promote carrier separation and then enhance photocatalytic CO 2 reduction. [Display omitted] • CdS/Bi 2 MoO 6 composite materials were synthesized by in-situ growth method. • CdS/Bi 2 MoO 6 exhibits excellent photocatalytic CO 2 reduction performance. • Properly designed interfacial electric fields and interfacial chemical bonds can effectively promote carrier separation. • The photo-corrosion is effectively suppressed in this photocatalytic system. Constructing strong interfacial electric fields to enhance the surface charge transport kinetics is an effective strategy for promoting CO 2 conversion. Herein, we present the fabrication of CdS-Bi 2 MoO 6 Z-scheme heterojunctions with a robust internal electric field (IEF) using an in situ growth technique, establishing chemical bonding between the components. The IEF at the interface can offer an impetus for the segregation and transportation of photogenerated carriers, while the Cd-O chemical bonding mode acts as a rapid conduit for these carriers, thereby reducing the charge transfer distance. As a result, the Z-scheme charge transfer is accelerated due to the synergistic influence of these two factors. Therefore, the optimized CdS/Bi 2 MoO 6 Z-scheme heterojunction possesses significantly enhanced dynamic carrier mobility, thus promoting the conversion of CO 2 to CO without the need for additional co-catalysts or sacrificial agents. This optimization yields a remarkable CO selectivity of up to 97%. Meanwhile, the expedited Z-scheme charge transfer mechanism is validated through X-ray photoelectron spectroscopy, Kelvin probe force microscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy. [ABSTRACT FROM AUTHOR]

Context: In a proof-of-concept study, we explore how a combined approach using the topology of the electron localization function (ELF) and the condensed dual descriptor (DD) function can guide the optimal orientation between reactants and mimic the potential energy surfaces of molecular systems at the beginning of the chemical pathway. The DD has been chosen for its ability to evaluate the regioselectivity of neutral and soft species and to potentially mimic the interaction energy obtained from the mutual interactions between nucleophilic and electrophilic regions of the building blocks under perturbative theory. Method: Our method has been illustrated with examples in which the optimal orientation of several systems can be successfully identified. The limitations of the presented model in predicting chemical reactivity are outlined in particular the influence of the selected condensation scheme. [ABSTRACT FROM AUTHOR]

In this study, wettability was employed to evaluate the effect of alkali activation by NaOH on different fly ash (FA) particle sizes. The results indicated that the surface wettability of FA particles with 13.8 μm increased from 0.025 g2/s to 0.034 g2/s after activation by the NaOH solution, which is suitable for silane modification and electroless plating. X-ray photoelectron spectroscopy (XPS) was used to analyze whether three kinds of silane coupling agents coated on FA surfaces could detect the chemical bonds between silane coupling agents coated on the FA surface and silver layers by shortening the plating time. The XPS results demonstrated that N-Ag coordination bonds can be detected by reducing silver plating time to 2 min for Ag-plated FA modified by N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (KH792). However, there were no chemical bonds detected for Ag-plated FA modified by γ-(2,3-epoxypropoxy)propytrimethoxysilane (KH560) and methyltrimethoxysilane (MTMS), even when the satellite peak of Ag disappeared after plating for 80 s. The SEM showed that Ag particles agglomerated on FA surfaces, and even a bare surface was found after modification by KH560 and MTMS, which further proved no chemical bonds between silver layers and the silane coupling agents. [ABSTRACT FROM AUTHOR]

This work is based on the productive idea of Mulliken about the alignment of electronegativities of atoms in the process of bond formation to their geometric mean value. The paper considers in detail the case of a binary molecule and obtains formulas for the dependence of the current values of the electronegativities of the two atoms forming the molecule on time, and finds a mathematical connection between the current and initial values of electronegativities. Also, in the work the theorem on the relation between the rates of alignment of electronegativities of atoms entering into chemical bonding is formulated and proved, and a special case of this theorem is considered. [ABSTRACT FROM AUTHOR]

Formation of molecular complexes and subsequent heterolytic halogen‐halogen bond splitting upon reactions of molecular Cl2 with nitrogen‐containing Lewis bases (LB) are computationally studied at M06‐2X/def2‐TZVPD and for selected compounds at CCSD(T)/aug‐cc‐pvtz//CCSD/aug‐cc‐pvtz levels of theory. Obtained results are compared with data for ICl and I2 molecules. Reaction pathways indicate, that in case of Cl2∙LB complexes the activation energies for the heterolytic Cl‐Cl bond splitting are lower than the activation energies of the homolytic splitting of Cl2 molecule into chlorine radicals. The heterolytic halogen splitting of molecular complexes of X2∙Py with formation of [XPy2]+…X3−$$ {\mathrm{X}}_3^{-} $$ contact ion pairs in the gas phase is slightly endothermic in case of Cl2 and I2, but slightly exothermic in the case of ICl. Formation of {[ClPy2]+…Cl3−$$ {\mathrm{Cl}}_3^{-} $$}2 dimers makes the overall process exothermic. Taking into account that polar solvents favor ionic species, generation of donor‐stabilized Cl+ in the presence of the Lewis bases is expected to be favorable. Thus, in polar solvents the oxidation pathway via donor‐stabilized Cl+ species is viable alternative to the homolytic Cl‐Cl bond breaking. [ABSTRACT FROM AUTHOR]

It is well known that Hirshfeld surfaces provide an easy and straightforward way of analysing intermolecular interactions in the crystal environment. The use of atomic Hirshfeld surfaces has also demonstrated that such surfaces carry information related to chemical bonds which allow a deeper evaluation of the structures. Here we briefly summarize the approach of atomic Hirshfeld surfaces while further evaluating the kind of information that can be retrieved from them. We show that the analysis of the metal‐centre Hirshfeld surfaces from structures refined via Hirshfeld Atom Refinement (HAR) allow accurate evaluation of contacts of type M...H, and that such contacts can be related to the overall shape of the surfaces. The compounds analysed were tetraaquabis(3‐carboxypropionato)metal(II), [M(C4H3O4)2(H2O)4], for metal(II)/M = manganese/Mn, cobalt/Co, nickel/Ni and zinc/Zn. We also evaluate the sensitivity of the surfaces by an investigation of seemingly flat surfaces through analysis of the curvature functions in the direction of C—C bonds. The obtained values not only demonstrate variations in curvature but also show a correlation with the hybridization of the C atoms involved in the bond. [ABSTRACT FROM AUTHOR]

The effect of a mixture of amino acids in hair care was studied. The repair effect of this raw material on hair was evaluated by stretching test and combing test. The experimental results showed that, the amino acid combination could increase the tension in the yield zone by 29.4% and reduce the combing work of hair by 22.4% dry combing and 18.1% wet combing. According to the results of spectral characterization, fluorescent penetration test and stress relaxation test, it could be concluded that the amino acid combination could repair the broken bonds by permeating into the hair and thus achieve the effect of toughening, and make the hair lipid transfer to the hair surface, which lead to a repairing effect on the hair surface and improved the hair combability. In particular, it had significant repair effect on the damaged hair caused by perm and hair coloring. [ABSTRACT FROM AUTHOR]

Surface metallization remains a promising approach for combining the unique properties of plastics and metals. To enhance the interfacial bonding of Ag/Cu coating on ABS substrate, a promising method combining chemical etching and self-assembly modification was proposed. The results showed that the adhesion strength of the Ag/Cu coating on ABS substrate was significantly improved to 6.71 N/cm. KMnO4 etching increased the –OH functional groups on the surface of ABS substrate, resulting in improved hydrophilicity. Specifically, the contact angle of distilled water decreased from 80.5° to 12.5° after 60 minutes of KMnO4 etching. The thiosilyl group of silane coupling agents hydrolyzed and condensed with –OH on the ABS surface, while the –SH end of silane coupling agents coupled with the silver film to form an S-Ag bond during the spray electroless plating process. This bond acts as a bridge between the substrate and the coating, thereby enhancing the adhesion strength of the coating. This study provides important theoretical and technical insights for the surface metallization of plastic. [ABSTRACT FROM AUTHOR]

In this paper, a dense and well‐adherent polydopamine‐Ti4O7/epoxy resin (PDA‐Ti4O7/EP) composite coating is successfully prepared. The modified grafting of Ti4O7 by polydopamine (PDA) is achieved through the coordination complexation of unstable catechol groups in PDA with coordination unsaturated Ti atoms in Ti4O7. The potentiodynamic polarization curve and electrochemical impedance spectroscopy test results show that the performance of the composite coating is improved compared with that of the pure epoxy coating, and the composite coating slows down the penetration of electrolytes and aggressive ions and improves the corrosion resistance. The composite coating with 2 wt.% PDA‐Ti4O7 filler shows the best corrosion resistance, and its |Z|0.01 Hz remains above 1011 Ω cm2 after 30 days of immersion in 3.5 wt% NaCl solution. This can be attributed to the good barrier property of PDA‐Ti4O7 filler, which carries NH2 and OH reactive groups, interacting with the resin and matrix to improve the dispersion of the filler and the adhesion of the composite coating. The NH2 group reacts with the epoxy group in the epoxy resin in a ring‐opening reaction, which avoids the agglomeration of the filler and the uniformly dispersed filler fills the pores in the coating due to curing to improve the denseness of the coating and give full play to the barrier property of the filler. At the same time, the hydrogen bonding between the filler and the OH group in the resin and the substrate increases the adhesion of the coating. In addition, the unstable catechol group in PDA chelates with iron ions to further improve the overall corrosion resistance of the coating. Highlights: A dense and well‐adherent PDA‐Ti4O7/EP coating is successfully prepared.PDA connect with Ti4O7 through coordination of catechol groups and Ti atom.PDA‐Ti4O7 are chemically bonded to the EP through a ring‐opening reaction.PDA‐Ti4O7 improves the crosslinking density and barrier ability of the coating. [ABSTRACT FROM AUTHOR]

In this paper, a dense and well‐adherent polydopamine‐Ti4O7/epoxy resin (PDA‐Ti4O7/EP) composite coating is successfully prepared. The modified grafting of Ti4O7 by polydopamine (PDA) is achieved through the coordination complexation of unstable catechol groups in PDA with coordination unsaturated Ti atoms in Ti4O7. The potentiodynamic polarization curve and electrochemical impedance spectroscopy test results show that the performance of the composite coating is improved compared with that of the pure epoxy coating, and the composite coating slows down the penetration of electrolytes and aggressive ions and improves the corrosion resistance. The composite coating with 2 wt.% PDA‐Ti4O7 filler shows the best corrosion resistance, and its |Z|0.01 Hz remains above 1011 Ω cm2 after 30 days of immersion in 3.5 wt% NaCl solution. This can be attributed to the good barrier property of PDA‐Ti4O7 filler, which carries NH2 and OH reactive groups, interacting with the resin and matrix to improve the dispersion of the filler and the adhesion of the composite coating. The NH2 group reacts with the epoxy group in the epoxy resin in a ring‐opening reaction, which avoids the agglomeration of the filler and the uniformly dispersed filler fills the pores in the coating due to curing to improve the denseness of the coating and give full play to the barrier property of the filler. At the same time, the hydrogen bonding between the filler and the OH group in the resin and the substrate increases the adhesion of the coating. In addition, the unstable catechol group in PDA chelates with iron ions to further improve the overall corrosion resistance of the coating. Highlights: A dense and well‐adherent PDA‐Ti4O7/EP coating is successfully prepared.PDA connect with Ti4O7 through coordination of catechol groups and Ti atom.PDA‐Ti4O7 are chemically bonded to the EP through a ring‐opening reaction.PDA‐Ti4O7 improves the crosslinking density and barrier ability of the coating. [ABSTRACT FROM AUTHOR]

In the present study, we concisely report on Be3's ground and several excited states of singlet, triplet, quintet, and septet spin symmetry at the MRCI/aug−cc−pV5Z computational level. We have constructed potential energy cuts along the bending coordinate under both C2v and Cs symmetry constraints. Both linear and bent configurations have been calculated that span an energy range of nearly 160 kcal/mol. The excited states result by promoting one, two or three valence electrons from the ground state's electronic configuration. This electronic promotion destroys its sigma (2center – 2e−) bond(s) and the resulting asymmetry is at the very heart of the Jahn–Teller distortion. [ABSTRACT FROM AUTHOR]

In the present study, we concisely report on Be3's ground and several excited states of singlet, triplet, quintet, and septet spin symmetry at the MRCI/aug−cc−pV5Z computational level. We have constructed potential energy cuts along the bending coordinate under both C2v and Cs symmetry constraints. Both linear and bent configurations have been calculated that span an energy range of nearly 160 kcal/mol. The excited states result by promoting one, two or three valence electrons from the ground state's electronic configuration. This electronic promotion destroys its sigma (2center – 2e−) bond(s) and the resulting asymmetry is at the very heart of the Jahn–Teller distortion. [ABSTRACT FROM AUTHOR]

Exploring new prototypes for a given chemical composition is of great importance and interest to several disciplines. As a famous semiconducting binary compound, InSe usually exhibits a two-dimensional layered structure with decent physical and mechanical properties. However, it is less noticed that InSe can also adopt a monoclinic structure, denoted as mcl-InSe. The synthesis of such a phase usually requires high-pressure conditions, and the knowledge is quite scarce on its chemical bonding, lattice dynamics, and thermal transport. Here in this work, by developing a facile method combining mechanical alloying and spark plasma sintering, we successfully synthesize mcl-InSe bulks with well-crystallized nanograins. The chemical bonding of mcl-InSe is understood as compared with layered InSe via charge analysis. Low cut-off frequencies of acoustic phonons and several low-lying optical modes are demonstrated. Noticeably, mcl-InSe exhibits a low room-temperature thermal conductivity of 0.6 W·m−1·K−1, which is smaller than that of other materials in the In–Se system and many other selenides. Low-temperature thermal analyses corroborate the role of nanograin boundaries and low-frequency optical phonons in scattering acoustic phonons. This work provides new insights into the non-common prototype of the InSe binary compound with potential applications in thermoelectrics or thermal insulation.

[Display omitted] Transition metal selenides (TMS) have been used to prepare hundreds of electrode materials for ion batteries due to their superior theoretical capacity, but have been repeatedly limited by the sluggish reaction kinetics and the enormous volume change during the repeated charge/discharge process. Here, we report a facile strategy to fabricate organic–inorganic composites by engineering a unique chemical bonding interface between TMS and conductive polymers. For the first time, poly(3,4-ethylenedioxythiophene) (PEDOT) is utilized to encapsulate iron diselenide (FeSe 2) nanoparticles by in situ polymerization, and the Fe-S bonds are meanwhile formed at the interface of FeSe 2 and PEDOT. The experimental analysis demonstrates the stability of Fe-S bonds during the sodiation/desodiation process and after long cycling, which can serve as a "bridge" for fast charge transfer and also serve as a "rivet" to stabilize the composite structure. When used for sodium ion storage, the composite offers an exceptionally long lifetime of up to 17,000 loops at 10 A/g without capacity degradation. In addition, it delivers a high specific capacity of 490.4 mAh/g and retains 60 % when the current density is amplified 150 times. The assembled full cell also exhibits excellent cycling stability. This work will provide a feasible way to improve the metal oxide/sulfide/selenides for long-life ion batteries. [ABSTRACT FROM AUTHOR]

Theoretical investigation of thermodynamic stability and bonding features of possible isomers of the molecular and ionic complexes of pyridine with molecular iodine and iodine monochloride IX (X = I,Cl) is presented. M06‐2X DFT functional is found to provide bond distances and dissociation energies which are close to those obtained at high‐level ab initio CCSD(T)/aug‐cc‐pvtz//CCSD/aug‐cc‐pvtz benchmark computations for the most stable isomers, formed via donation of a lone pair of nitrogen atom of pyridine to the iodine atom. These isomers are by 23–33 kJ mol−1 (in case of I2) and by 39–56 kJ mol−1 (in case of ICl) more stable than other molecular complexes. T‐shaped π‐σ* bonded isomers turn out to be energetically comparable with van der Waals bound compounds. Among the ionic isomers, structures featuring [IPy2]+ cation with I3− or ICl2− counterions are more stable. Oligomerization favors ionic isomers starting from the tetrameric clusters of the composition (IX)4Py4. [ABSTRACT FROM AUTHOR]

Structural, electronic, and vibrational properties of phosphates LiCdPO4, NaCdPO4, RbCdPO4, CsCdPO4 are studied by density functional theory and Hartree–Fock methods using the CRYSTAL17 code in the LCAO basis set with gradient PBE, PBEsol and hybrid PBE0, PBEsol0 functionals. It is shown that the crystal structures contain infinite zigzag chains consisting of [CdO6] octahedra and [PO4] tetrahedra inside which there are alkali metal atoms. By the Gaussian broadening of normal long-wave modes IR absorption and Raman spectra are calculated. Differences in the number of spectral bands, their polarization and intensities are related to different symmetry space groups of the crystals. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Processing of Materials / Elektronnaya Obrabotka Materialov is the property of Institute of Applied Physics 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.)

Misconceptions are a problem always faced in education, one of which is in the field of science, especially in chemistry. One of the chemical materials that students consider pretty challenging to understand because it is abstract, making it possible for misconceptions to occur, is chemical bonding. Misconceptions among students need to be identified quickly so they can be addressed immediately so they do not interfere with further learning. This research aims to determine the relationship between gender and the misconceptions of SMA YPK in Merauke Regency regarding chemical bonding material. Research data was analyzed quantitatively descriptively using the Polytomus Rasch Model. The respondents in this study were 76 Class X high school students who were selected using simple random sampling with 46 female and 30 male students. The research results showed that male students' average percentage of misconceptions was 31.9% (medium category), and female students were 18.6% (low type). The question indicators show that the highest percentage of misconceptions is in the question indicator for determining valence electrons; male students are 60% (medium category), and female students are 49% (medium type). Based on the overall misconception results regarding chemical bond indicators, gender influences the level of misconceptions of high school students in the city of Merauke.

Abstract Hyperuricemia (HUA) is a metabolic disease caused by excessive uric acid in patients. Flavonoids have attracted extensive attention due to their safety, effectiveness, and little side effects in the treatment of HUA and inhibition of xanthine oxidase (XO) activity. In this paper, the studies on the treatment of HUA and the inhibition of XO activity by flavonoids (including flavones, flavonols, flavanones, flavanols, isoflavonoids, anthocyanins, and chalcones) were comprehensively reviewed from the aspects of structure–activity relationship and animal experiments. Results showed that hydrogen bonds and hydrophobic interactions were the two most important forces involved in the interaction between flavonoids and XO. Flavonoids could combine with the hydrophobic cavity of XO to cause changes in XO structure and influence the action of enzyme and substrate, thereby decreasing the catalytic activity of XO. Moreover, flavonoids undergo a series of metabolic reactions in the organism, which plays a role in alleviating HUA by affecting the expression of related genes and proteins (e.g., glucose transporter 9, urate transporter 1, and organic anion transporter 1) in the kidneys, liver, and intestinal tract of the organism and changing the internal environment in organs. In addition, this paper provides new perspectives on the shortcomings of the current research, to promote the in‐depth development and application of flavonoids.

In this study, wettability was employed to evaluate the effect of alkali activation by NaOH on different fly ash (FA) particle sizes. The results indicated that the surface wettability of FA particles with 13.8 μm increased from 0.025 g2/s to 0.034 g2/s after activation by the NaOH solution, which is suitable for silane modification and electroless plating. X-ray photoelectron spectroscopy (XPS) was used to analyze whether three kinds of silane coupling agents coated on FA surfaces could detect the chemical bonds between silane coupling agents coated on the FA surface and silver layers by shortening the plating time. The XPS results demonstrated that N-Ag coordination bonds can be detected by reducing silver plating time to 2 min for Ag-plated FA modified by N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (KH792). However, there were no chemical bonds detected for Ag-plated FA modified by γ-(2,3-epoxypropoxy)propytrimethoxysilane (KH560) and methyltrimethoxysilane (MTMS), even when the satellite peak of Ag disappeared after plating for 80 s. The SEM showed that Ag particles agglomerated on FA surfaces, and even a bare surface was found after modification by KH560 and MTMS, which further proved no chemical bonds between silver layers and the silane coupling agents.

Chemical bonding is one of the core concepts in the whole field of chemistry and provides a very effective way of communication. It must be clear that chemical bonds are not real, they are artificially abstracted concepts. To accurately describe chemical bonding, various models or theories have been proposed throughout history. The most widely used models are the electron-pair bonding model and hybrid orbital theory. However, the rules of thumb have their limitations, as evident in the explanation of hypervalent molecules. We suggest that in teaching, hypervalent molecules should be used as examples to explicitly point out the shortcomings of empirical rules in describing chemical bonding to younger students. In another hand, molecular orbital theory or modern valence bond theory can be used on bonding analysis for senior students. It is expected that students maintain an open-minded attitude towards the behavior of chemical bonding and cultivate spirit of scientific inquiry. [ABSTRACT FROM AUTHOR]

Context: This article intends to show a new way to setup and solve chemical bonds which can be incorporated into molecules. The new approach is analytical and purely based on simple math and science. We need analytical methods in our molecular theory which can be used to obtain results with our eyes open to the process. The utilization of computer software is fine as long as the user understands what the software is exactly doing. An analytical molecular theory can be utilized in different areas of science including chemistry. It can be also an asset in classrooms to better train our future generations, making them better "thinkers" and ready to tackle the complicated issues in our changing world. This article first introduces a new analytical approach to study chemical bonds and then goes through several examples of chemical bonds to show the applicability of the suggested approach. Methods: All of the calculations and figures presented in this article are done by the use of Microsoft excel spreadsheet. The presented approach does not need any sophisticated software and/or heavy computations. [ABSTRACT FROM AUTHOR]

Context: This article intends to show a new way to setup and solve chemical bonds which can be incorporated into molecules. The new approach is analytical and purely based on simple math and science. We need analytical methods in our molecular theory which can be used to obtain results with our eyes open to the process. The utilization of computer software is fine as long as the user understands what the software is exactly doing. An analytical molecular theory can be utilized in different areas of science including chemistry. It can be also an asset in classrooms to better train our future generations, making them better "thinkers" and ready to tackle the complicated issues in our changing world. This article first introduces a new analytical approach to study chemical bonds and then goes through several examples of chemical bonds to show the applicability of the suggested approach. Methods: All of the calculations and figures presented in this article are done by the use of Microsoft excel spreadsheet. The presented approach does not need any sophisticated software and/or heavy computations. [ABSTRACT FROM AUTHOR]

Despite the ubiquitous presence of amine oxides in chemistry, there is no consensus about the nature of the NO bond in these compounds. In this work, we have used electron density analysis to investigate the nature of this bond in substituted amine oxides, R3NO, and have compared it with the nature of the NO bond in hydroxylamines, R2NOR, and model molecules that have well‐established chemical bond character. The results showed that the NO bond length and relative stability are proportional to the inductive effect of the substituents. Quantum chemical topology, natural bond orbitals (NBO), and natural resonance theory (NRT) analyses indicated that the NO bond is polar covalent in all the studied amine oxides, but the ionic contribution is different. NBO and NRT analyses revealed that molecules with more electronegative substituents have strongly delocalized NO and NR bonds, whereas molecules with electropositive substituents have localized bonds. [ABSTRACT FROM AUTHOR]

The chemical bonding of 3C2O and 3N2C is analyzed in this work through the topological quantum approach using the electronic localization function (ELF) at the CASSCF level and by energetic calculations at the CCSD(T) level using four different basis sets. The results show that the dissociation of the molecules occurs via cleavage of the C‐C bond in the case of 3C2O, while in the case of 3N2C, it occurs via cleavage of the N‐C bond. Furthermore, the results obtained with ELF show monosynaptic basins containing excess electrons and disynaptic basins with a low electron population. This leads us to indicate the existence of three‐center‐two‐electron bonds according to previous results. From the valence bond model, a series of resonance structures have been proposed that support our calculations. In addition, the proposed structures have an ionic nature, indicating a charge shift character. [ABSTRACT FROM AUTHOR]

MgTi 1- x (Co 1/3 Nb 2/3) x O 3 (x = 0–0.3) ceramics were prepared by a solid-state reaction method. The (Co,Mg) 4 Nb 2 O 9 and MgTiO 3 phases formed solid solutions, which presented an ilmenite-type with R -3 space group. In low (Co 1/3 Nb 2/3)4+ ion content, the (Co,Mg) 4 Nb 2 O 9 dissolves in MgTiO 3 matrix, whereas the MgTiO 3 dissolves in (Co,Mg) 4 Nb 2 O 9 with high (Co 1/3 Nb 2/3)4+ ion content. In the transition from MgTiO 3 to (Co,Mg) 4 Nb 2 O 9 matrix, MgTiO 3 and (Co,Mg) 4 Nb 2 O 9 phases can coexist. A secondary phase, MgTi 2 O 5 , existed in the x = 0 sample. The introduction of (Co 1/3 Nb 2/3)4+ inhibited the formation of the second phase and promoted grain growth. The variation trend of the dielectric constant (ε r) was the same as the theoretical dielectric constant (ε theo), indicating that the ε r was dominated by the ion polarizability. The stable microstructure, which was caused by the high total lattice energy, enhanced the quality factor (Qf) value. And an ultrahigh Qf value (∼492 500 GHz) was obtained for MgTi 0.96 (Co 1/3 Nb 2/3) 0.04 O 3 ceramics sintered at 1250 °C. Moreover, the TiO 6 octahedral distortion, which is caused by the ion substitution, contributes to the change in bond restoring force. The TiO 6 octahedral distortion conduces to the fluctuations of the temperature coefficient of resonance frequency (τ f) value. [ABSTRACT FROM AUTHOR]

Methane (CH 4) adsorption-induced swelling is one of the critical factors controlling the permeability of coalbed methane (CBM). CH 4 adsorption alters the molecular structure of coal so as to induce coal swelling, and many uncertainties still exist in the process. In this study, the change in the molecular structures of different chemical structures by CH 4 adsorption was investigated using the Grand Canonical Monte Carlo method to simulate the alteration of bond lengths and bond angles during swelling. The results demonstrate that the alteration of chemical structure is more extensive than a chemical bond, which is the critical factor causing the swelling behavior. Owing to the complex molecular structure of coal, among the different types of chemical structures, the C-O-C (-O-) chemical structure showed the most significant change in bond angle, with the largest degree of change is 12.89%. Compared with other chemical structures, the C-C-C (aromatic -C-) chemical structures are more stable and the largest degree of change is 0.65%. For the different types of chemical bonds, the C-C chemical bonds showed the most significant change in bond lengths, with the largest degree of change is 2.94%. And the O-H chemical bond showed the smallest change, with the largest degree of change is 0.79%. Considering the structure evolution of coal, the C-O-C (-O-) chemical structure decreases with increasing maturity and changes to the greatest after the adsorption of methane. The aromatic structure increases and the degree of deformation decreases, which is consistent with the previous experimental values for swelling. These results reveal the details of different types of chemical group deformation, providing a molecular-level insight into adsorption swelling and permeability changes. [ABSTRACT FROM AUTHOR]

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco 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.)

The empty-space-induced depletion region in photoelectrodes severely exacerbates the recombination of electron–hole pairs, thereby reducing the photoelectrochemical (PEC) analytical performance. Herein, the chemical bond that can suppress the potential barrier and overcome the high energy barrier of out-of-plane Ohmic or Schottky contact is introduced into the PEC sensor to eliminate the depletion region and dramatically promote the separation of electron–hole pairs. Specifically, three-dimensional (3D) hierarchically wheatear-like TiO2 (HWT) nanostructures featuring a large surface area to absorb incident light are crafted as the substrate. The facile carbonized strategy is further employed to engineer the Ti-C chemical bond, serving as the touchstone. The average PL lifetime of HWT-C (4.14 ns) is much shorter than that of the 3D HWT (8.57 ns) due to the promoting effect of the chemically bonded structure on carrier separation. Consequently, the 3D HWT-C covalent photoelectrode (600 μA/cm2) exhibits a 3.6-fold increase in photocurrent density compared with the 3D HWT (167 μA/cm2). Ultimately, the model analyte of the tumor marker is detected, and the linear range is 0.02 ng/mL–100 ng/mL with a detection limitation of 0.007 ng/mL. This work provides a basic understanding of chemical bonds in tuning charge separation and insights on strategies for designing high-performance PEC sensors. [ABSTRACT FROM AUTHOR]

The microwave dielectric properties of olivine-structured CaLnGaO 4 (Ln = Pr, Yb) ceramics with a 1:1 order at the octahedra site were investigated using bond valance, P–V-L chemical bond theory, and Raman spectra. The theoretical permittivity ε r (C-M) values are far below the porosity-corrected ε r (Corr) values, indicating that the dielectric polarizabilities of CaLnGaO 4 (Ln = Pr, Yb) were underestimated, and this phenomenon was mainly influenced by rattling cations. The difference in ε r is mainly determined by the ionic polarizability per unit volume (α m / V m). The τ f values of CaLnGaO 4 (Ln = Pr, Yb) did not decrease with the decrease of the ε r , which was due to the larger positive temperature coefficient of dielectric constant (τ ε) and the higher coefficient of thermal expansion (α L) of CaPrGaO 4 ceramic compared to CaYbGaO 4 , respectively. The difference in Q × f values between CaPrGaO 4 and CaYbGaO 4 is mainly due to the strain of chemical bonds and the Raman spectrum. [ABSTRACT FROM AUTHOR]

The main objective of this work was to design a large-scale cold atmospheric plasma brush (LSCAPB) that can produce a perfectly homogenous large area capable of producing plasma with a length of about 5 cm for studying the inactivation effect of plasma on Gram-positive and Gram-negative bacteria that commonly implicated in Food infections. Gram-positive (Listeria monocytogenes, Bacillus cereus) and Gram-negative (Salmonella typhi, Vibrio cholerae) bacteria with an initial population density of 1.5 × 108 CFU mL−1 were treated, and their survivability with plasma exposure was examined. The effect of plasma exposure in the reduction of bacteria population was investigated using OD600 absorbance, and changes in cell structure and the membrane were studied by scanning electron microscopy analysis. For applied voltage 25 kV and after 10 min the reduction of cold plasma treatment for S. typhi, V. cholerae, B. cereus, and L. monocytogenes were decreased from 1.5 × 108 to 0.3 × 102, 1.5 × 102, 0.6 × 103, and 0.7 × 105 CFU mL−1, respectively. Comet assay analysis was used for studying the effect of plasma exposure on DNA damage, and changes in chemical bonds were analyzed by FTIR analysis. So, the best destruction is obtained at the voltage of 25 kV for all types of bacteria. This study indicates that the inactivation effect of LSCAPB correlates with the kind of bacteria. We demonstrated LSCAPB can be one of the most efficient methods for the inactivation of different types of bacteria. [ABSTRACT FROM AUTHOR]

The nature of the bridging C−C bond in [1.1.1]propellane has been a topic of much debate, and finally it has been established to be a charge‐shift bond. But the question remains: Can we restore the "lost" covalency of this charge shift bond? Herein we have attempted to investigate the nature of the bridging C−C bond, by replacing the CH2 groups at the wing positions with NH, O, and S. Detailed analyses using atoms in molecules (AIM) and electron localization function (ELF) reveal that the bridging bond emerges as a covalent bond upon substitution with S. [ABSTRACT FROM AUTHOR]

Experimental charge density analysis is conducted on the coordination compound tetraaquabis(hydrogenmaleato)nickel(II), which exhibits a short intramolecular hydrogen bond. Through topological analysis, the nature of Ni—O bonds is concluded to be intermediate between ionic and covalent, but mainly presenting an ionic character, while the short hydrogen bond is classified as covalent in nature. The compound was also analysed after Hirshfeld atom refinement performed using NoSpherA2. A topological analysis was conducted on the molecular wavefunction and the results are compared with those obtained from experiment. In general, there is good agreement between the refinements, and the chemical bonds involving H atoms are in better agreement with what is expected from neutron data after HAR than they are after multipole refinement. [ABSTRACT FROM AUTHOR]

Synergistic effects between hard carbons and soft carbons are proven to be helpful for improving the electrochemical performance of carbonaceous anode for potassium-ion batteries (PIBs). However, the phase separation of precursors limits the synergistic effects and improvement of electrochemical performance. Here, inspired by the esterification reaction, the precursors of two sorts of carbon are connected at the molecular level, which boosts the synergistic effects in hybrid carbon, resulting in excellent electrochemical kinetics and low charge/discharge voltage. Consequently, the hybrid carbon anode exhibited a high specific capacity of 121 mAh·g−1 at 3.2 A·g−1, a high-rate capability, and stable cycling performance. After 500 cycles at 1 A·g−1, the average capacity fading is only 0.078% per cycle. [ABSTRACT FROM AUTHOR]

Ions appear as active components in diverse materials. Here, the bonding energy between mechanically interlocked molecules (MIMs) or their acyclic/cyclic molecular derivatives and i) Cl− and Br− ions and/or ii) Na+ and K+ ions, have been investigated. The chemical environment provided by MIMs is less preferably to recognize ionic species compared to unconstrained interactions that are furnished by acyclic molecules. However, MIMs can be more adequate structures for ionic recognition than cyclic compounds if a chemical arrangement of the bond sites that relevantly support more favorable interactions with ions compared to Pauli repulsive ambient is provided. The hydrogen replacement by electron donor (−NH2) or acceptor (−NO2) groups in MIMs favors the anion/cation recognition due to decreased Pauli repulsion energy and/or more attractive non‐covalent bonds. This study clarifies the chemical environment provided by MIMs to interact with ions and highlights these molecules as relevant structures to realize ionic sensing. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of the effect of a substrate chemical bonding type on the mechanical properties of coated systems (CSs) of a soft film/hard substrate type. The Cu/MgO and Cu/Si coated systems, as well as MgO and Si substrate crystals, which have similar hardness values but different types of chemical bonds, were studied. Various elastoplastic parameters were compared. The general and specific features of the deformation process under nanomicroindentation were identified. It has been established that general properties, such as 'pop-in', 'pop-out', 'elbow' effects, indentation size effect (ISE), are determined by the stress state created in the material during the indenter penetration and depend on the magnitude of the applied load and the film thickness. The specific properties, Young's modulus, hardness, relaxation parameters depend on the crystal structure and elastoplastic properties of the film and substrate material. The difference in the type of chemical bonding of the substrates, despite the close values of hardness, changes the elastoplastic properties and deformation mechanism of the composite structure as a whole, thereby expanding the possibility of creating new materials required for modern technology. Highlights Study of the effect of a substrate chemical bonding type on the mechanical properties of soft film/hard substrate (Cu/MgO, Cu/Si) coated systems. The difference in the type of chemical bonding of the substrates, despite the close values ⁣⁣of hardness, changes the elastoplastic properties and deformation mechanism of the composite structure as a whole. [ABSTRACT FROM AUTHOR]

“What do you want to be when you grow up?” is a common question posed to children, and answers such as firefighter, policeman, athlete, doctor, or teacher are probably just as common. Some, like Oliver Sacks, recall an early fascination with metals, the periodic table, and chemical reactions that planted the seeds for the later pursuit of the natural sciences or medicine (neurology in his case). We are familiar with memories of chemists that include their first chemistry set, followed by complaints by parents over strange smells and close calls due to particularly exothermic reactions. For others, including myself, a future in research remained more obscure until a later period in adolescence or perhaps even the undergraduate years. Rather than seeking out a field, the field finds you. In actuality, teachers and mentors with expertise in and enthusiasm for a field exert a force that charts a path toward scientific research throughout life. Here, I stress the importance of terrific teachers and mentors from high school onwards to the undergraduate, Ph.D., and postdoc years for setting me on a track (and on occasion preventing me from derailing) to research in structural chemistry and molecular mechanism using crystallography as the main tool.

The covalent bond is a classical topic in science education because it is fundamental to a considerable number of other concepts and by its ability to interpret several chemical phenomena. However, the process of learning this concept presents some difficulties discussed here. This article brings together the conceptions related to the covalent bond, identified, and reported from other studies, to find similarities and to organize what is known about the topic in epistemological themes. In this paper, it was conducted a systematic review using 3 databases, reaching more than 200 reports, and classified 253 sentences of misconceptions in 7 epistemological themes. The main contribution of this article is the classification of misconceptions into themes, which enables teachers and researchers to easily identify a topic considering its complexity. This review shows different misconceptions over the same topic, how misinterpretations can appear over all the models and theories related to the covalent bond, heterogeneity of school levels with the same misconception and mixing of theoretical foundations. Finally, we claim that the knowledge of this wide sight can be especially important to further lesson/unity planning, studies, and understanding of how to make a better transition between one topic to another.

The titled relationship is considered in this paper in terms of the (de)localization phenomenon and its emanation in the positional coordinate space. The similarity between the strength of bonding of a topological atom (in the sense of the population of the corresponding atomic surface) and the delocalization index is discussed. Based on the hypervirial theorem, a scalar one‐particle field is suggested to visualize the consequences of (de)localization for the formation of bonding. [ABSTRACT FROM AUTHOR]

Molecular orbital theory is an important chemical bonding theory and also a difficult point in the study of general chemistry. In this article, the problems often encountered by beginners of molecular orbital theory are sorted out and analyzed, and the application of molecular orbital theory is expanded. By tracing the formation and development of the molecular orbital theory, combined with the requirements of the Chemistry Olympiad test questions, summarization and analysis are carried out to deepen the understanding of the molecular orbital theory and promote the teaching of the molecular orbital theory. [ABSTRACT FROM AUTHOR]

Some critical comments are made on the current understanding and description of chemical bonding and on the recent trend to propose new bonding models. [ABSTRACT FROM AUTHOR]

Purpose: To investigate direct bonding of a 10-MDP-based cement to two novel translucent yttria-stabilized tetragonal zirconia polycrystal ceramics (4Y-TZP, 5Y-TZP) and observe the influence of thermocycling on this bonding. Materials and Methods: Powders of presintered and isostatically pressed 5Y-TZP, 4Y-TZP and 3Y-TZP were mixed with a 10-MDP-based cement (Panavia F 2.0), then stored in deionized water for 48 h at 37°C or thermocycled 10,000 times. Raman spectroscopy and Fourier-transform infrared spectroscopy were used to assess the presence of a functional group (PO32-) that could indicate bonding before and after thermocycling. X-ray photoelectron spectroscopy was used to identify the presence of the suspected Zr-O-P bond in the same specimens. A shearbond strength (SBS) test was conducted based on ISO 29022:2013. Results: Marked peaks assigned to the asymmetric vibrations of the PO32- functional group were observed in both zirconias before and after thermocycling. The binding energy corresponding to Zr-O-P interactions (531.5 eV) was masked by the aluminosilicate in the filler of the cement. Shear bond strengths were approximately 20 MPa after water storage and approximately 6 MPa after thermocycling. No differences were found between the control group and the translucent zirconias. Conclusion: Direct bonding of the 10-MDP-based cement to both 4Y-TZP and 5Y-TZP was highly plausible. Both 4YTZP and 5Y-TZP may be promising alternatives to glass-ceramic restorations. [ABSTRACT FROM AUTHOR]

[Display omitted] The density of electronic states and the XPS spectrum of FmO 2 valence electrons in the binding energy range from 0 to ∼40 eV have been calculated by the fully relativistic method of discrete variation. It is shown that the electrons of the outer and inner valence molecular orbitals (MOs) with binding energies from 0 to ∼15 eV and from ∼15 to ∼40 eV, respectively, contribute to the complex structure of the XPS spectrum of FmO 2. The FmO 2 MO diagram was constructed and the contribution of the electrons of the outer and inner valence MOs to the chemical bond was estimated. [ABSTRACT FROM AUTHOR]