Self-assembled soft alloy with Frank-Kasper phases beyond metals.

Soft building blocks, such as micelles, cells or soap bubbles, tend to adopt near-spherical geometry when densely packed together. As a result, their packing structures do not extend beyond those discovered in metallic glasses, quasicrystals and crystals. Here we report the emergence of two Frank-Kasper phases from the self-assembly of five-fold symmetric molecular pentagons. The µ phase, an important intermediate in superalloys, is indexed in soft matter, whereas the ϕ phase exhibits a structure distinct from known Frank-Kasper phases in metallic systems. We find a broad size and shape distribution of self-assembled mesoatoms formed by molecular pentagons while approaching equilibrium that contribute to the unique packing structures. This work provides insight into the manipulation of soft building blocks that deviate from the typical spherical geometry and opens avenues for the fabrication of 'soft alloy' structures that were previously unattainable in metal alloys.

A Thiol-Michael Approach Towards Versatile Functionalized Cyclic Titanium-Oxo Clusters.

In expanding our research activities of superlattice engineering, designing new giant molecules is the necessary first step. One attempt is to use inorganic transition metal clusters as building blocks. Efficient functionalization of chemically precise transition metal clusters, however, remains a great challenge to material scientists. Herein, we report an efficient thiol-Michael addition approach for the modifications of cyclic titanium-oxo cluster (CTOC). Several advantages, including high efficiency, mild reaction condition, capability of complete addition, high atom economy, as well as high functional group tolerance were demonstrated. This approach can afford high yields of fully functionalized CTOCs, which provides a powerful platform for achieving versatile functionalization of precise transition metal clusters and further applications.

Doping effects on the antibonding states and carriers of two-dimensional PC6.

The absence of a bandgap in pristine graphene severely restricts its application, and there is high demand for other novel two-dimensional (2D) materials. PC6 has recently emerged as a promising 2D material with a direct band gap and ultrahigh carrier mobility. In light of the remarkable properties of an intrinsic PC6 monolayer, it would be intriguing to find out whether a doped PC6 monolayer displays properties superior to the pure system. In this study, we have performed density functional theory calculations to understand the doping effects of both P-site and C-site substitution in PC6 and, for the first time, we discovered doping-related impurity-level anomalies in this system. We successfully explained why no donor or acceptor defect states exist in the band structures of XP-PC6 (X = C, Ge, Sn, O, S, Se, or Te). In group-IV-substituted systems, these dopant states hybridize with host states near the Fermi level rather than act as acceptors, which is deemed to be a potential way to tune the mobility of PC6. In the case of group-VI substitution, the underlying mechanism relating to doping anomalies arises from excess electrons occupying antibonding states.

The effect of pressure on the structural, electronic and vibrational properties of solid carbon dioxide phases.

The structural, electronic and vibrational properties of solid carbon dioxide phases (I, II, III, and IV) under high pressure are studied using first-principles calculations. The calculated structural parameters are in good agreement with the experimental values. The third-order Birch-Murnaghan equation of state is fitted, and the corresponding parameters are obtained. We obtained the phase boundary points of each phase and plotted the phase diagram of solid carbon dioxide. The influence of pressure on the band structure and density of states is studied. The vibrational properties of the four phases of carbon dioxide were studied in detail, and the infrared and Raman spectra of the four phases were obtained. It can be seen from the calculated spectrum that the number and frequency of vibration peaks are in good agreement with the experimental values. And, we also analyze the influence of pressure on the frequency of vibration mode.

Ordered Mesoporous Silica Pyrolyzed from Single-Source Self-Assembled Organic-Inorganic Giant Surfactants.

We report the preparation of hexagonal mesoporous silica from single-source giant surfactants constructed via dihydroxyl-functionlized polyhedral oligomeric silsesquioxane (DPOSS) heads and a polystyrene (PS) tail. After thermal annealing, the obtained well-ordered hexagonal hybrid was pyrolyzed to afford well-ordered mesoporous silica. A high porosity (e.g., 581 m2/g) and a uniform and narrow pore size distribution (e.g., 3.3 nm) were achieved. Mesoporous silica in diverse shapes and morphologies were achieved by processing the precursor. When the PS tail length was increased, the pore size expanded accordingly. Moreover, such pyrolyzed, ordered mesoporous silica can help to increase both efficiency and stability of nanocatalysts.

Phenotypic plasticity may help lizards cope with increasingly variable temperatures.

Temperature variability is predicted to increase in the coming century due to climate change. However, the biological impact of increased temperature variability on animals remains largely unexplored. Here, we experimentally exposed gravid viviparous lizards (Eremias multiocellata) to two thermal environments [constant daily maximum (CDM) versus variable daily maximum (VDM) treatment with the same average temperature] to address maternal and offspring responses to increased variability in ambient temperature. Females from the VDM treatment delayed parturition, but produced similar litter sizes and litter masses as did CDM females. Offspring from the VDM treatment selected higher body temperatures, had higher metabolic rates and higher growth rates, and grew to a similar size as those from the CDM treatment despite having a shorter growth period prior to hibernation. Therefore, phenotypic plasticity may be critical for lizards to respond effectively to climate change, and its role in responding to increasingly variable temperatures warrants further attention.

Diastereoselective carbonyl allylation with simple olefins enabled by palladium complex-catalyzed C-H oxidative borylation.

A highly diastereoselective Pd-catalyzed carbonyl allylation of aldehydes and isatins directly using simple acyclic olefins as allylating reagents is described. This transformation is actually a sequential process consisting of a Pd-catalyzed oxidative allylic C-H borylation and an allylboration of carbonyls accelerated by phosphoric acid, wherein a wide scope of olefins could be tolerated. The oxidant is revealed to play a key role in the successful realization of the allylic C-H activation-based allylation.

A pilot study on the expression of circadian clock genes in the alveolar bone of mice with periodontitis.

This study aimed to investigate the expression of circadian clock genes in mouse alveolar bone, and the possible reasons for these changes. Fifty C57 mice were orally inoculated with P. gingivalis, establishing a model of periodontitis using healthy mice as controls. The alveolar bone of both groups was taken for micro-computed tomography scanning to measure the amount of attachment loss, and the relative expression of mRNA in each clock gene and periodontitis related inflammatory factor was detected by real-time fluorescence quantitative polymerase chain reaction (qRT-PCR). After the establishment of the mouse model, the height of alveolar bone in the periodontitis group was significantly lower than that in the normal group (p < 0.05). The relative transcriptional level of Bmal1, Per2, and Cry1 mRNA was in the circadian rhythm in the normal group (p ≤ 0.05), while in the periodontitis group, its circadian rhythm disappeared and the transcriptional level characteristics were changed. Interleukin (IL)-6, tumor necrosis factor-alpha (TNF-α), and interferon (IFN-γ) mRNA transcriptional level were elevated in the periodontitis group compared to the normal group. In conclusion, the mRNA transcriptional level of Bmal1, Per2, and Cry1 in alveolar bone of normal mice has circadian rhythm, but the rhythm disappears under the condition of periodontitis, and the cause of its occurrence may be related to inflammatory cytokines.

Pressure and temperature effects on the Raman spectra of LLM-105.

Currently, only one crystal structure of LLM-105 (2,6-diamino-3,5-dinitropyrazine-1-oxide) (P21/n) has been discovered, and there are still debates on its phase transition point and phase diagram. Based on previous work, we performed crystal structure, Raman spectra, and vibrational properties calculations on LLM-105 crystal. Our results indicate that the crystal structure of LLM-105 remains stable until compressed to 49 GPa, beyond which it may undergo two phase transitions at pressure intervals of 49.0-49.1 GPa and 51.4-51.5 GPa, respectively. Analysis of Raman shift results suggests that these two phase transitions may be reversible, with an intermediate phase possibly acting as a transition phase. Additionally, based on the quasi-harmonic approximation, we fitted the experimental data of LLM-105 lattice expansion state, obtaining the volume at zero pressure and using it for Raman spectra calculations. The results demonstrated the accuracy of this quasi-harmonic approximation method in describing the redshift of Raman peaks during the heating process and the excitation ratio of Raman peaks in different wavenumber ranges.

Structural, electronic, and mechanical properties of Y7Ru4InGe12: a first-principle study.

This study reports a theoretical examination of the structural, electronic, and mechanical properties of the tetragonal structure of Y7Ru4InGe12 by using the generalized gradient approximation of the density functional theory and the plane wave ab initio pseudopotential method. We have mainly studied the electronic properties of the compound. The calculated results of the band structure show that the addition of rare earth elements has a greater effect on Fermi levels. By studying density of states, it is found that Y, Ge, and Ru atoms contribute most to Fermi levels. At the same time, we also studied the partial density of states of Y and Ge atoms in different positions. By calculating the value of B (bulk modulus)/G (shear modulus), Poisson's ratio and Cauchy's pressure found that the compound exhibited ductility. Poisson's ratio can also be used to define the bonding properties of compounds. The results of the calculations show that the superconductivity of Y7Ru4InGe12 is due to significant metallic bonding. The calculated elastic constants show that the compound is mechanically stable.

The comparative study of structural, electronic, and optical properties of hydrogen peroxide and its dihydrate under pressures: first-principle calculations.

Hydrogen peroxide (H2O2) is used as a fuel and propellant in fuel cells and rockets due to its prominent oxidizing and combustion properties. In addition, hydrogen peroxide, as the energetic material with the simplest molecular structure, exhibits general detonation performance under external stimulation. Based on the first-principle method, we calculated the two crystal structure, electronic properties related to sensitivity closely, optical properties of pure hydrogen peroxide, and 48wt.% hydrogen peroxide (H6O4) under pressure. We found that the band gaps of H2O2 and H6O4 become larger under pressure and the former is larger than the latter; neither has the tendency of metallization phase change. The added peak II of TDOS from H6O4 compared with H2O2 come from molecular H2O in crystal structure. The pressure-induced peak (peak 2 and peak II of TDOS from H2O2 and H6O4) splitting is caused by changes (stronger) in the intermolecular hydrogen bond environment in the crystal under pressure. The specific macroscopic optical properties have the characteristics of overall blue-shift under pressure, which is due to the blueshift of the conduction band and the increase of the band gap. We hope to provide some reference and guidance for deeper future research.

Enantioselective Hydroaminomethylation of Olefins Enabled by Rh/Brønsted Acid Relay Catalysis.

Herein, by employing a rhodium catalyst with a commercial ligand and a phosphoric acid catalyst, highly chemo-, regio-, and enantioselective hydroaminomethylation of olefins is realized through a relay catalytic hydroformylation/dynamic kinetic reductive amination process. The method features mild conditions (1 bar of syngas, room temperature in most cases), high yields (up to 99%), and high enantioselectivities (up to >99.5:0.5 er). Besides styrenes, acrylamides also provided the products with high yields and enantioselectivities. Aliphatic alkenes and vinyl esters are also applicable for the current method, albeit lower yields and enantioselectivities were obtained.