Isomeric Porous Cu(I) Triazolate Frameworks Showing Periodic and Aperiodic Flexibility for Efficient CO Separation.

Guest-induced (crystal-to-crystal) transformation, i.e., periodic flexibility, is a typical feature of molecule-based crystalline porous materials, but its role for adsorptive separation is controversial.

Designing dynamic coordination bonds in polar hybrid crystals for a high-temperature ferroelastic transition.

Ferroelastic materials have gained widespread attention as promising candidates for mechanical switches, shape memory, and information processing. Their phase-transition mechanisms usually originate from conventional order-disorder and/or displacive types, while those involving dynamic coordination bonds are still scarce. Herein, based on a strategic molecular design of organic cations, we report three new polar hybrid crystals with a generic formula of AA'RbBiCl (A = A' = MeSO for 1; A = MeSO and A' = MeN for 2; A = A' = MeNNH for 3).

Quasi-open Cu(I) sites for efficient CO separation with high O/HO tolerance.

Carbon monoxide (CO) separation relies on chemical adsorption but suffers from the difficulty of desorption and instability of open metal sites against O, HO and so on. Here we demonstrate quasi-open metal sites with hidden or shielded coordination sites as a promising solution. Possessing the trigonal coordination geometry (sp), Cu(I) ions in porous frameworks show weak physical adsorption for non-target guests.

Facile Solution-Refluxing Synthesis and Photocatalytic Dye Degradation of a Dynamic Covalent Organic Framework.

Covalent organic frameworks (COFs), as a novel crystalline porous adsorbent, have been attracting significant attention for their synthesis and application exploration due to the advantages of designability, stability, and functionalization. Herein, through increasing the concentration of the acid catalyst, a facile solution-refluxing synthesis method was developed for the preparation of a three-dimensional dynamic COF material, COF-300, with high yields (>90%) and high space−time yields (>28 kg m−3 day−1). This synthesis method not only permits gram-scale synthesis, but also yields products that well maintain porosity and unique guest-dependent dynamic behavior.

A reaction rate measurement experimental program of China experimental fast reactor.

The study of the nuclear reaction rate distribution in the MOX core of China Experimental Fast Reactor is a necessary condition for obtaining the operating license. From the characteristics of core structure, both the principle of experimental and experimental system are studies, emphasized on the scheme design such as the size of foils, the irradiation power and counting rate. Firstly, based on the Monte Carlo Code（MCNP）and NJOY codes, the distribution of reaction rates is obtained.

Above-Room-Temperature Ferroelastic Phase Transitions in Two Tetrafluoroborate-Based Hexagonal Molecular Perovskites.

ABX-type molecular perovskites provide an important platform to tune phase transitions, via judiciously choosing A-, B-, and X-site components, to approach advanced functional materials for applications. Although tetrafluoroborate can act as X-site component to assemble ten instances of ABX molecular perovskites, only two of them possess hexagonal perovskite structures. Herein, we report two tetrafluoroborate-based hexagonal molecular perovskites, A[Na(BF)], by judiciously choosing two different A-site cations: 1-methyl-1,4-diazabicyclo[2.

Guest-Driven Light-Induced Spin Change in an Azobenzene Loaded Metal-Organic Framework.

Stimuli-responsive materials that can be reversibly switched by light are of immense interest. Among them, photo-responsive spin crossover (SCO) complexes have great promises to combine the photoactive inputs with multifaceted outputs into switchable materials and devices. However, the reversible control the spin-state change by photochromic guests is still challenging.

Room-temperature ferroelectric and ferroelastic orders coexisting in a new tetrafluoroborate-based perovskite.

The coexistence of multiferroic orders has attracted increasing attention for its potential applications in multiple-state memory, switches, and computing, but it is still challenging to design single-phase crystalline materials hosting multiferroic orders at above room temperature. By utilizing versatile ABX-type perovskites as a structural model, we judiciously introduced a polar organic cation with easily changeable conformations into a tetrafluoroborate-based perovskite system, and successfully obtained an unprecedented molecular perovskite, (homopiperazine-1,4-diium)[K(BF)], hosting both ferroelectricity and ferroelasticity at above room temperature. By using the combined techniques of variable-temperature single-crystal X-ray structural analyses, differential scanning calorimetry, and dielectric, second harmonic generation, and piezoresponse force microscopy measurements, we demonstrated the domain structures for ferroelectric and ferroelastic orders, and furthermore disclosed how the delicate interplay between stepwise changed dynamics of organic cations and cooperative deformation of the inorganic framework induces ferroelectric and ferroelastic phase transitions at 311 K and 455 K, respectively.

An unprecedented hexagonal double perovskite organic-inorganic hybrid ferroelastic material: (piperidinium)[KBiCl].

An unprecedented A2MIMIIIX6-type double perovskite adopting a fully hexagonal BaNiO3-type structure, (piperidinium)2[KBiCl6], undergoes a 2/mF1[combining macron] ferroelastic phase transition at 285 K with a spontaneous strain of 0.0615, arising from the order-disorder transition of organic cations together with the synchronous displacement of inorganic chains.

Nitroprusside as a promising building block to assemble an organic-inorganic hybrid for thermo-responsive switching materials.

We present a new hybrid compound, namely (Me2NH2)[KFe(CN)5(NO)], possessing a unique nitroprusside-based inorganic host framework in 4-connected sra topology encapsulating organic guest cations. The flexible host-guest hydrogen bonds and synchronously deformed inorganic framework give rise to thermal-responsive switching behaviours on both thermal expansion and nonlinear optical properties during the phase transition at around room temperature.

Enhancing switchable dielectric property for crystalline supramolecular rotor compounds by adding polar components.

Two new compounds were obtained by assembling the [(2-methoxy-5-nitro-anilinium)(18-crown-6)]+ cation with non-polar PF6- and polar SO3CF3- anions, respectively. Benefiting from its polar anion, the SO3CF3- compound reveals a more significant dielectric switching behaviour during phase transition, demonstrating an effective strategy to enhance the dielectric property by adding polar components.

[Influence of the effect of general anaesthesia and restraint during dental treatment on dental anxiety and behavior in children].

Objective: To compare the level of dental anxiety and dental behavior between dental fear children with dental treatment under general anaesthesia (GA) and those under restraint.

Methods: The GA group included 31 dental fear children aged 4-6-year-old who received dental treatment under the GA. The restraint group included 31 dental fear children aged 4-6-year-old who received dental treatment under the restraint.

Clinical comparison of Fuji VII and a resin sealant in children at high and low risk of caries.

The purpose was to compare the retention and caries preventive effect of Fuji VII and a resin-based sealant in children at high risk (HR) and low risk (LR) of caries. Fifty-seven schoolchildren (150 teeth) with completely erupted bilateral permanent first molars were included. The study was a split-mouth, randomized trial.