Weak Bonds Research Articles

A Carborane-Derived Proton-Coupled Electron Transfer Reagent.

Reagents capable of concerted proton-electron transfer (CPET) reactions can access reaction pathways with lower reaction barriers compared to stepwise pathways involving electron transfer (ET) and proton transfer (PT). To realize reductive multielectron/proton transformations involving CPET, one approach that has shown recent promise involves coupling a cobaltocene ET site with a protonated arylamine Brønsted acid PT site. This strategy colocalizes the electron/proton in a matter compatible with a CPET step and net reductive electrocatalysis. To probe the generality of such an approach a class of C,C'-diaryl-o-carboranes is herein explored as a conceptual substitute for the cobaltocene subunit, with an arylamine linkage still serving as a colocalized Brønsted base suitable for protonation. The featured o-carborane (PhCbPhN) can be reduced and protonated to generate an N-H bond with a weak effective bond dissociation free energy (BDFEeff) of 31 kcal/mol, estimated with measured thermodynamic data. This N-H bond is among the lowest measured element-H bonds for analyzed nonmetal compounds. Distinct solid-state crystal structures of the one- and two-electron reduced forms of diaryl-o-carboranes are disclosed to gain insight into their well-behaved redox characteristics. The singly reduced, protonated form of the diaryl-o-carborane can mediate multi-ET/PT reductions of azoarenes, diphenylfumarate, and nitrotoluene. In contrast to the aforementioned cobaltocene system, available mechanistic data disclosed herein support these reactions occurring by a rate-limiting ET step and not a CPET step. A relevant hydrogen evolution reaction (HER) reaction was also studied, with data pointing to a PT/ET/PT mechanism, where the reduced carborane core is itself highly stable to protonation.

Research Progress of Human Biomimetic Self-Healing Materials.

Humans can heal themselves after injury, which inspires researchers to develop bionic self-healing materials. Such materials not only equipped with the self-repair capacities akin to those of the human body, but also emulate the mechanical properties of human organs, including the tensile resilience of muscles, the fatigue resistance of skin, and the elevated modulus typical of cartilage. Based on the design concept of imitating the structure of human organs, the bionic self-healing material perfectly solves the problem of poor mechanical properties of self-healing materials caused by weak bond energy and inter-chain flow. This review discusses various organ-inspired self-healing materials in detail, summarizes their synthetic principles and introduces their fascinating mechanical properties. Finally, the application prospects of bionic self-healing polymer materials, such as bio-strain sensors, self-healing anticorrosive coatings, biomedical detection, etc., are outlined. Considering the excellent comprehensive performance and multi-functions of human biomimetic self-healing polymers, more outstanding sustainable materials will be developed, accelerating research progress in self-healing materials and realizing environmentally friendly products in multiple fields.

Quantum Chemical Model Calculations of Adhesion and Dissociation between Epoxy Resin and Si-Containing Molecules

There is no doubt that when solid surfaces are modified, the functional groups and atoms directly bonded to solid atoms play a major role in adsorption interactions with molecules or resins. In this study, the adhesion and dissociation between epoxy resin and molecules containing Si atoms were analyzed. The analysis, conducted in contact with the solid surface of silicon, utilized quantum chemical calculations based on a molecular model. We compared some Si-containing molecular models to test quantum chemical calculations that contribute to the study of adhesion and dissociation between epoxy resins and solid surfaces somehow other than simple potential energy curve calculations. The AFIR (artificial force induced reaction) method, implemented in the GRRM (global reaction route mapping) program, was employed to separate an epoxy resin model molecule and three types of silicon compounds (Si(CH3)2(OH)2, Si(CH3)4, and (CH3)2SiF2) in three directions, determining their minimum dissociation energy when changing the applied energy by 2.5 kJ/mol. In systems with weak hydrogen bonds, such as Si(CH3)4 or (CH3)2SiF2, the energy required for dissociation was not large; however, in systems with strong hydrogen bonds, such as Si(CH3)2(OH)2, dissociation was more difficult in the vertical direction. Although anisotropy due to hydroxyl groups was calculated in the horizontal direction, dissociation remained relatively easy.

Construction and Evaluation of pH‐Responsive Nitrogen‐Containing Metal–Organic Frameworks as Oral Drug Carriers

ABSTRACTMetal–organic framework (MOF) is a porous material composed of metal ions/clusters and organic ligands. It has attracted much attention due to its high specific surface area, good biocompatibility, chemical modifiability, and diversity of components. Among many MOFs, zirconium‐based MOFs are particularly suitable for biological applications due to their optimal stability and low toxicity to hydrolysis. However, due to the weak coordination bonds between many metal clusters and organic ligands, most MOFs are prone to collapse in acidic environments, and the stability of MOFs as drug carriers cannot be guaranteed so that they cannot be widely used as oral drug carriers. This study synthesized the three MOFs using metal Zr ion clusters as the center and different nitrogen‐containing organic ligands, which are stable in gastric acid, namely, UiO‐66‐PDC, UiO‐66‐NH2, and UiO‐66‐NO2. The anionic drug loxoprofen (LOX) was loaded and characterized using scanning electron microscopy, infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and x‐ray diffraction. The adsorption and release behaviors of LOX and the three MOFs were studied from the molecular point of view by computer simulation. A series of behaviors and mechanisms of pH‐responsive nitrogen‐containing MOFs as oral drug carriers were further explored through rat pharmacokinetic experiments, the everted gut sac experiments, and intestinal absorption mechanism experiments. The experimental results show that there is a strong electrostatic interaction between anionic drug LOX and UiO‐66‐PDC under simulated gastric acid environment, which prolongs the half‐life of the drug, proving that LOX@UiO‐66‐PDC is a promising new oral drug delivery system.

Electronic structure evolution during martensitic phase transition in all-d-metal Heusler compounds: the case of Pd2MnTi

Abstract In this study, taking Pd2MnTi as a representative example, the electronic structure evolution during martensitic phase transition in all-d-metal Heusler compounds was systematically studied and revealed theoretically. The calculation and theoretical analysis suggest that Pd2MnTi is not stable in cubic structure and prones to transform to low-symmetric tetragonal structure. By tetragonal deformation, the shrinkage of lattice parameters and the decrease of symmetry promote the electron accumulation between Pd and its first nearest neighboring Ti atom, resulting in the increased covalent hybridization. The occurrence of pesudogap in density of states (DOSs) of tetragonal Pd2MnTi near the Fermi level also verifies the enhancement of covalent bond. Comparatively, the stronger interatomic bond in tetragonal Pd2MnTi, i.e., covalent bond here, would strengthen interatomic coupling and consequently lower the energy of the material. By the martensitic phase transition, more stable state in energy was achieved. Thus, based on the analysis of electronic structure evolution, the nature of martensitic phase transition is a process wherein symmetry breaking weakens the original weak chemical bonds in high-symmetric parent phase and induces the strong chemical bond to lower the energy of the materials and achieve a more stable state. This study could help to deepen the understanding of martensitic phase transition and the exploration of novel materials for potential technical applications.

High-Fidelity Supramolecular Chirality Transportation Enabled Through Chalcogen Bonding.

The formation of asymmetric microenvironments in proteins benefits from precise transportation of chirality across multiple levels through weak bonds in the folding and assembly process, which inspires the rational design and fabrication of artificial chiral materials. Herein, the chalcogen bonding-directed precise transportation of supramolecular chirality toward multiple levels is reported to aid the fabrication of chiroptical materials. Benzochalcogenadiazole (O, S, Se) motifs are conjugated to amino acid residues, and the solid-state assemblies afforded selective supramolecular chirality with handedness depending on the kinds of chalcogen atoms and amino acids. The chalcogen-N sequence assisted by hydrogen bonding synergistically allows for the complexation with pyrene conjugated aryl carboxylic acids to give macroscopic helical structures with active circular dichroism and circularly polarized luminescence, of which handedness is precisely determined by the pristine chiral species. Then the further application of chiral benzochalcogenadiazole motifs as seeds in directing handedness of benzamide via symmetry breaking is realized. Behaving as the dopants, embedding into the matrix of benzophenone induces the room temperature phosphorescence, whereby the thermal chiroptical switch is fabricated with color-tunable phosphorescent circularly polarized luminescence. This work utilized benzochalcogenadiazole-based chiral building units to accomplish precise transportation of supramolecular chirality in coassemblies with high-fidelity, achieving flexible manipulation of chiroptical properties and macroscopic helical sense.

Mild and Subtle Synthesis of β-Ketoenamine COFs with High Crystallinity and Controllable Solubility Guided by a Monomer Preassembly Strategy.

The stability of covalent organic frameworks (COFs) is crucial for their applications in demanding environments. However, increasing the stability of COFs often comes with challenges such as higher synthesis difficulty, lower crystal quality, and reduced controllability during synthesis, making it difficult to regulate dimensions and morphology, thereby impacting the processing and shaping of stable COFs. Herein, the study presents a novel confined polymerization approach guided by hydrogen bonding preassembly to synthesize a soluble and stable COF featuring β-ketoenamine linkage. The presence of relatively weaker hydrogen bonds accelerates the orderly arrangement of monomers, ensuring appropriate spacing, and orientations among functional groups. This facilitates efficient covalent polymerization, leading to the creation of the framework while minimizing the "self-correction" mechanism during crystal growth, thereby enhancing the efficiency of COF synthesis. Furthermore, this method offers precise control over the size of the synthesized COF. The resulting crystalline COF can be toggled between dissolution and precipitation states, facilitating the fabrication of mixed matrix membranes (MMMs) through leveraging the solubility properties of COF. Overall, this pioneering strategy yields valuable insights for advancing weak bond assembly-mediated confined polymerization approaches, the controlled synthesis of stable COFs, and the preparation and processing of soluble COFs in diverse applications.

A Review on the Role of Hydrogen Bonds in Organic Electrode Materials

AbstractOrganic electrode materials (OEMs) hold significant development potential in the field of batteries and are regarded as excellent complementary materials to resource‐limited inorganic electrode materials, which have recently been the subject of extensive research. As research deepens, an increasing number of scholars recognize the influence of weak bond interactions on the properties of OEMs. Generally, weak bond interactions have more pronounced effects on organic materials compared to inorganic ones. Among various weak interactions, hydrogen bonds are particularly noteworthy, having been proven to play crucial roles in adjusting electrode charge distribution, stabilizing crystal structures, and inhibiting cyclic dissolution. The studies of hydrogen bonds in OEMs are therefore of paramount importance for guiding their future development. In this review, we primarily summarize the research progress in hydrogen bond science within OEMs and discuss future research directions and development prospects in this area. Hoping to provide valuable references for the advancement of OEMs.

Crystal Structure and Li-Fe Order in Synthetic Mg(2-2x)LixFe3+x(SiO4) Olivine Structure.

Olivines are naturally occurring silicates consisting of isolated (SiO4)4- tetrahedra linked through M1O6 and M2O6 octahedra. In this study, we report the structural and crystal-chemical characterization of synthetic olivine crystals containing up to 25% Li-Fe3+ synthesized using the flux growth technique. Based on site scattering, <M1-O> and <M2-O> mean bond lengths, and charge neutrality of the chemical formula, we found a perfect ordering of Li and Fe3+ at the two distinct M1 and M2 sites. Unrestrained linear extrapolation to a hypothetical isostructural LiFe3+(SiO4) composition aligns well with the tabulated ionic radii of Li and Fe3+. Comparison made with the isostructural LiSc(SiO4) reveals that the Li-centered M2O6 octahedron has a significant capacity to distort in order to accommodate structural stresses, due to the relatively weak Li-O bond, while still achieving a bond valence sum that closely matches the formal charge of Li+. This behavior suggests the potential feasibility of an extended Li + Fe3+ for 2 Mg coupled substitution within the olivine structure. The reported structure of the LiFe3+(SiO4) endmember in the literature, despite its apparent matching of cell dimensions and space group with olivine, exhibits extremely unconventional crystal chemical features, raising questions about its validity. Given the importance of the suitability of Li-insertion in LiFeSiO4 as electrodes in rechargeable Li-ion batteries, further studies are needed to investigate its crystal structure and crystal chemistry.

Laser-Driven Modular Precision Chemistry of Graphene Using λ3-iodanes.

The emerging laser writing represents an efficient and promising strategy for covalent two dimensional (2D)-patterning of graphene yet remains a challenging task due to the lack of applicable reagents. Here, we report a versatile approach for covalent laser patterning of graphene using a family of trivalent organic iodine compounds as effective reagents, allowing for the engraving of a library of functionalities onto the graphene surface. The relatively weak iodine-centered bonds within these compounds can readily undergo laser-induced cleavage to in situ generate radicals localized to the irradiated regions for graphene binding, thus completing the covalent 2D-structuring of this 2D-film. The tailor-made attachment of distinct functional moieties with varying electrical properties as well as their thermally reversible binding manner enables programming the surface properties of graphene. With this delicate strategy the bottleneck of a limited scope of functional groups patterned onto the graphene surface upon laser writing is tackled.

A 0D Ge(II)-Halide-Based Perovskite with Enhanced Semiconducting Behavior for Electronic Capacitors.

Perovskite materials have surged to the forefront of materials science, captivating researchers worldwide with their distinctive crystal lattice arrangement and remarkable optical, electric and dielectric attributes. The current study focuses on the development of a novel zero-dimensional (0D) Ge(II)-based hybrid perovskite, formulated as NH3(CH2)2NH3GeF6, and synthesized through a gradual evaporation process conducted at room temperature. The crystal structure is characterized by an arrangement of organic cations and isolated octahedral [GeF6]2- groups. This configuration is stabilized by relatively weak intermolecular bonds. A comprehensive analysis of the material's thermal properties using differential scanning calorimetry (DSC) revealed a distinct phase transition occurring at approximately 323 K, which was further confirmed through electrical measurements. The studied compound provided a broad absorption range across the visible spectrum and an optical band gap of 3.30 eV, indicating its potential for semiconducting applications in optoelectronic devices. Photoluminescence PL analysis displays a blueish broad-band emission with a high color rendering index CRI value of 91, when excited at 325 nm. This emission primarily originates from the self-trapped excitons (STEs) recombination in the inorganic [GeF6]2-. Herein, the temperature-dependent behavior of grain conductivity exhibited an Arrhenius-type pattern, with an activation energy (E a) of 0.46 eV, confirming the semiconductor nature of the investigated compound. In addition, a deep investigation of the alternating current conductivity, analyzed using Jonscher's law, demonstrates that the conduction mechanism is effectively described by the correlated barrier hopping (CBH) model. The dielectric performances show a significant dielectric constant (ε' ∼ 103). Thus, all these interesting physical properties of this hybrid perovskite have paved the way for advancements in various technological applications, particularly in the field of electronic capacitors.

Bonding strength of steel and concrete containing Palm Oil Fuel Ash (POFA) and Expanded Polystyrene (EPS)

The usage of recycled materials in concrete has become popular recently. This paper focuses on a study related to the bonding between steel and concrete containing expanded polystyrene beads (EPS) and palm oil fuel ash (POFA) as replacement material. The EPS were used as fine aggregate replacement, and POFA was used as cement replacement. The replacement percentages for EPS and POFA in the concrete were limited to a range of 0-30% and 0-10%, respectively. Previous studies have identified the potential of POFA and EPS as concrete substances. The typical issue with EPS-containing concrete is its characteristic weakness, which leads to a compromised bond with steel. This occurs because EPS fails to effectively interact with cement, resulting in a weak bond and low compressive strength. Consequently, in this study, POFA is introduced as an addition to enhance the bond strength between EPS-containing concrete and steel. Pull-out tests in this study seem to represent the bonding performance between concrete and steel. The 10% of POFA in concrete seems might improve its performance in terms of compression strength, and bonding between concrete and steel.

Polymeric Manganese(II) Acetate Derivatives: Syntheses, Crystal Structures and Magnetic Properties

AbstractThree novel polymeric Mn(II) acetate derivatives, identified as {[Mn2.5(OH)(CH3COO)4] ⋅ 0.5CH3OH ⋅ 0.5CH3CN}n (1), {[Mn3(CH3CO O)6] ⋅ 0.5CH3CN}n (2) and {Mn1.5K(CH3COO)4}n (3), have been successfully prepared by systematically adjusting the ratio of reactants and using the 2‐mercapto‐5‐methyl‐1,3,4‐thiadiazole (Hmmt) as the template agent. These three complexes can be regarded as the different crystalline forms of Mn(CH3COO)2 under different reaction conditions. Single‐crystal X‐ray diffraction analyses revealed that 1 and 2 feature the unique three‐dimensional (3D) framework. For 3, it displays a 2D structure, which is further assembled to form a 3D extended network via the weak hydrogen bond interactions. Magnetic studies confirmed that 1 and 2 show antiferromagnetic interactions, and 1 displays a long‐range ordering phase below the critical temperature (Tc) of 7.8 K. In addition, magnetisation data collected for 1–2 yield low magnetic entropy changes, which can be attributed to the strong antiferromagnetic interactions among the Mn(II) centres.

Comparative Assessment of Water Models in Protein-Glycan Interaction: Insights from Alchemical Free Energy Calculations and Molecular Dynamics Simulations.

Accurate computational simulations of protein-glycan dynamics are crucial for a comprehensive understanding of critical biological mechanisms, including host-pathogen interactions, immune system defenses, and intercellular communication. The accuracy of these simulations, including molecular dynamics (MD) simulation and alchemical free energy calculations, critically relies on the appropriate parameters, including the water model, because of the extensive hydrogen bonding with glycan hydroxyl groups. However, a systematic evaluation of water models' accuracy in simulating protein-glycan interaction at the molecular level is still lacking. In this study, we used full atomistic MD simulations and alchemical absolute binding free energy (ABFE) calculations to investigate the performance of five distinct water models in six protein-glycan complex systems. We evaluated water models' impact on structural dynamics and binding affinity through over 5.8 μs of simulation time per system. Our results reveal that most protein-glycan complexes are stable in the overall structural dynamics regardless of the water model used, while some show obvious fluctuations with specific water models. More importantly, we discover that the stability of the binding motif's conformation is dependent on the water model chosen when its residues form weak hydrogen bonds with the glycan. The water model also influences the conformational stability of the glycan in its bound state according to density functional theory (DFT) calculations. Using alchemical ABFE calculations, we find that the OPC water model exhibits exceptional consistency with experimental binding affinity data, whereas commonly used models such as TIP3P are less accurate. The findings demonstrate how different water models affect protein-glycan interactions and the accuracy of binding affinity calculations, which is crucial in developing therapeutic strategies targeting these interactions.

Synthesis, Crystal Structure and Antifungal Activity of (E)-1-(4-Methylbenzylidene)-4-(3-Isopropylphenyl) Thiosemicarbazone: Quantum Chemical and Experimental Studies.

A novel (E)-1-(4-methylbenzylidene)-4-(3-isopropylphenyl) thiosemicarbazone was synthesized in a one-pot four-step synthetic route. Fourier transform infrared spectroscopy (FTIR), 1H and 13C nuclear magnetic resonances (NMR), single-crystal X-ray diffraction, and UV-visible absorption spectroscopy were utilized to confirm the successful preparation of the title compound. Single-crystal data indicated that the intramolecular hydrogen bond N(3)-H(3)···N(1) and intermolecular hydrogen bond N(2)-H(2)···S(1) (1 - x, 1 - y, 1 - z) existed in the crystal structure and packing of the title compound. Besides the covalent interaction, the non-covalent weak intramolecular hydrogen bond N(3)-H(3)···N(1) discussed by atoms in molecules (AIM) theory also functioned in maintaining the title compound's crystal structure. The strong intermolecular hydrogen bond N(2)-H(2)···S(1) (1 - x, 1 - y, 1 - z) discussed by Hirshfeld surface analysis played a major role in maintaining the title compound's crystal packing. The local maximum and minimum electrostatic potential of the title compound was predicted by electrostatic potential (ESP) analysis. The UV-visible spectra and HOMO-LUMO analysis revealed that the title compound has a low ΔEHOMO-LUMO energy gap (3.86 eV), which implied its high chemical reactivity due to the easy occurrence of charge transfer interactions within the molecule. Molecular docking and in vitro antifungal assays evidenced that its antifungal activity is comparable to the reported pyrimethanil, indicating its usage as a potential candidate for future antifungal drugs.

Comparative QSAR and q-RASAR modeling for aquatic toxicity of organic chemicals to three trout species: O. Clarkii, S. Namaycush, and S. Fontinalis

Oncorhynchus clarkii, Salvelinus fontinalis, and Salvelinus namaycush are vital trout species in North America, crucial for maintaining ecological balance, economic stability, and human health. These species thrive in cold, unpolluted waters and are highly vulnerable to contaminants. Given the rapid proliferation of industrial organic chemicals, traditional in vivo toxicity testing methods are inadequate to ensure timely and comprehensive risk assessments. Therefore, we employed in silico tools, namely Quantitative Structure-Activity Relationship (QSAR) and Quantitative Read-Across Structure-Activity Relationship (q-RASAR), to efficiently predict the aquatic toxicity of chemicals. Utilizing acute median lethal concentration (LC50) data from the US EPA’s ToxValDB, we developed the first-ever species-specific QSAR and q-RASAR models. The q-RASAR models outperformed traditional QSAR models by achieving higher internal and external statistical quality for each species. Key toxicity-determining descriptors included electrotopological state indices, autocorrelation descriptors, and similarity-based RASAR descriptors. For O. clarkii, the presence of chlorine atoms and rotatable bonds significantly influenced toxicity. S. fontinalis toxicity was strongly affected by polarizability, and van der Waals volumes, while S. namaycush showed sensitivity to weak hydrogen bond acceptors and topological complexity. The models predicted the toxicity of 1172 external compounds, identifying the most and least toxic chemicals for each species. This study not only offers the first comprehensive q-RASAR models for predicting trout species-specific toxicity but also provides novel insights into species-specific toxicological modes of action. The results contribute significantly to chemical screening and prioritization in aquatic risk assessments, effectively filling critical data gaps and advancing predictive modeling techniques.

Amorphous Nanobelts for Efficient Electrocatalytic Ammonia Production.

One-dimensional (1D) amorphous nanomaterials combine the advantages of high active site concentration of amorphous structure, high specific surface area and efficient charge transfer and mass transport of 1D materials, so they present promising opportunities for catalysis. However, a significant challenge involves achieving a balance between the high orientation of 1D morphology and the isotropy of amorphous structure, which severely obstructs the controllable preparation of 1D amorphous materials. Guided by the hard-soft acids-bases theory, here we develop a general strategy for preparing 1D amorphous nanomaterials through the precise modulation of bond strength between metal ions and organic ligands for a moderated fastness. The soft base dodecanethiol (DT) is multifunctionally served as both structure-regulating agent and morphology-directing agent. Compared with the borderline acids (e.g. Fe2+, Co2+, Ni2+) to construct amorphous structure, soft acid of Cu+ which produced crystalline nanobelts can still be amorphized by reducing the hardness of Cu ions through redox reaction to weak Cu-SR bond. Due to the combined advantages of amorphous structure and one-dimensional morphology, amorphous CuDT nanobelts exhibited excellent electrocatalytic activity in electrochemical nitrate reduction, outperformed the most of the reported Cu-based catalysts. This work will effectively bridge the gap between traditional 1D crystalline nanomaterials and amorphization preparation.

Effect of nitrogen- and oxygen-containing functional groups on adsorption of styrene by activated carbon: A theoretical study by density functional theory

Activated carbon adsorption is one of the mainstream technologies for controlling VOCs emissions such as styrene, with surface functional groups significantly influencing its adsorption capacity. The adsorption mechanism of styrene on functionalized AC was studied using DFT calculations. Results show that nitrogen and oxygen doping altered the local electrostatic potential of AC, reduced the average LOLIPOP index of the internal ring, and enhanced styrene adsorption to varying degrees. AC with hydroxyl and pyrrolic groups significantly improved styrene adsorption (Ead = -13.76, -12.86 kcal/mol). Styrene adsorption on AC is a physisorption process, primarily dominated by π-π stacking, with dispersion interactions as the main contributor (61–70 %). In addition to π-π stacking, weak hydrogen bonds between styrene and AC functionalized with hydroxyl, amino, and pyrrolic N groups further enhance the adsorption capacity. Enhancing the synergistic effect of hydrogen bonding and π-π stacking is key to significantly improving adsorption capacity.

The effects of hydrogen on the bonding properties of SiC/Cu interface via first-principles calculations

Ceramic/metal interfaces own great importance of technology, but the weak interface bond limits their applications. In this work, the effects of doping H element on the stability and bonding properties of SiC/Cu interface are studied by first principles calculations. In order to study the stability of interface, the potential surfaces were firstly studied for the C and Si terminated SiC/Cu interfaces. The C terminated interface is more stable than the Si terminated interface, which contributes the largest work of adhesion of 3.998 J/m2. The effects of hydrogen on the interface bonding properties were further studied. The occupation properties of hydrogen atoms were then studied, the hydrogen tends to occupy the octahedral position with negative formation energy. To reveal the bonding strength of SiC/Cu interface, the tensile simulations were carried out. The hydrogen owns obvious effects on the tensile strength depends on its occupation site. The movement and diffusion properties of hydrogen atoms in the interface zone were studied combining molecular dynamics and climbing image nudged elastic band method. Finally, the bonding mechanisms were analyzed by combining charge density, state density, differential charge and bader charge. Based on the above calculation results, it is found that for SiC(001)/Cu(111) interface, the H element generally has a negative impact on the bonding properties of SiC/Cu interface.

Identification of a novel RHCE*Ce (829G > A) allele associated with absence of C and e antigens expression.

The Rh blood group antigens are encoded by the RHD and RHCE genes, which possess a remarkable degree of polymorphism owing to their high homologous structures. These variants of the RH genes can lead to absence or weak expression of antigens. Analysis of RHCE genotyping by Polymerase Chain Reaction (PCR-SSP) method specific to detect c.48G, c.48C, 109 bp insertion of IVS2, c.201A and c.307C and RhCE phenotyping, were conducted in 316 Chinese patients in previous study. One patient with discrepancy typing result was collected for further RhCE serologic typing using microcolumn gel method and tube method in saline using monoclonal antibodies. PacBio sequencing was performed for RHCE, RHD and RHAG complete sequence analysis. 3D molecular models of the protein with the wild-type and mutant residue were generated using the DynaMut web server. The effect of the mutation on the protein function was predicted by PolyPhen-2 software. One male patient of Chinese Han was detected with RHCE*C allele showed by PCR-SSP method but ccEE phenotype. Further PacBio sequencing identified one normal RHCE*cE allele and one RHCE*Ce allele carried a novel c.829G > A (p.Gly277Arg) variant, which the encoded amino acid located in the ninth transmembrane segment of RhCE protein. Crystallisation analysis of 3D molecular models revealed that the substitution at Arg277 leads to the formation of additional hydrogen bonds, including weak hydrogen bonds between multiple atoms. It also results in hydrophobic ion interactions between Arg277 and Ala244. This mutation is predicted to have a damaging effect on protein function. One novel RHCE*Ce allele with c.829G > A (p.Gly277Arg) variant was identified to resulting in the absence or weak expression of C and e antigens.