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Since the revelation of significant negative thermal expansion (NTE) across an extensive temperature range in cubic ScF 3 , there has been a notable surge of interest in fluorides of the ReO 3 -type structure. However, with the exceptions of ScF 3 , nearly all ReO 3 -type fluorides at low temperature crystallize in a rhombohedral structure in which the thermal expansion becomes strong positive. In this work, we reinvestigated the phase transition mechanism of α -AlF 3 from rhombohedral to cubic phase by combining in situ X-ray diffraction, in situ Raman spectra and first principles calculation. Our research has unveiled that this phase transition is driven by a phonon mode A 1g , which is associated with the tilting of octahedral structures. The α -AlF 3 shows seriously anharmonic lattice dynamics with A 1g phonon mode exhibiting softening behavior even far below the transition temperature. Anharmonic analysis based on Balkanski model suggests that A 1g mode decays into a longitudinal acoustic (LA) phonon and a transverse optical phonon E g , which have large amplitudes and promote the titling of AlF 6 octahedra, final leading to the phase transition to the cubic structure. This finding further indicates the potential for tuning NTE materials through phonon engineering. • Computational and experimental reinvestigation of the temperature-induced phase transition mechanism of α-AlF 3. • Anharmonic analysis of the Balkanski model shows that the phase transition is mainly driven by an anharmonic phonon (A 1g). • Possible decay paths for the A 1g mode include longitudinal acoustic (LA) phonons and transverse optical E g phonons. [ABSTRACT FROM AUTHOR]

[Display omitted] • The structural evolution and relative stability for Ta 2 Mg n (n = 10–20) clusters. • The properties of electrons and bonds of the most stable structures are elucidated. • The aromaticity of Ta 2 Mg 16,18 is clarified by ICSS method. • The source of electronic excitation of Ta 2 B 16, 18 clusters is confirmed. In this work, we combine the CALYPSO method with DFT calculations to conduct a comprehensive structural search of Ta 2 B n (n = 10 ∼ 20) clusters. Among all the candidate structures obtained by CALYPSO searching, the structures of ground state Ta 2 B n clusters at each size are determined according to their total energy and symmetry. The relative stability analysis indicates that the ground state Ta 2 B 16 and Ta 2 B 18 clusters with the unique bicyclic boron ring and two Ta atoms as axes exhibit excellent stability in the studied range, with their HOMO-LUMO gaps of 2.374 and 2.640 eV, respectively. The bonding analyses reveal that the strong interaction between two Ta atoms and the outer B 16/18 bicyclic ring dominates their significant stability, especially the interaction between Ta- d AOs and B- s / p AOs. It is confirmed that both Ta 2 B 16 and Ta 2 B 18 have strong aromaticity by examining the isochemical shielding surface (ICSS). Finally, the strong coupling between their outer boron rings (B 16/18) and two Ta atoms inside the structures of Ta 2 B 16 and Ta 2 B 18 is further elucidated by the electronic absorption spectrum (UV–vis and CTS). [ABSTRACT FROM AUTHOR]

Y 2 O 3 : x% Er3+ (x=5, 7, 10, 12, 15) and Y 2 O 3 : 10% Er3+，x% K+ (x=0, 1, 3, 5, 7, 10, 15) phosphors were successfully prepared by a low-temperature combustion method. The structure as well as the absorption/emission spectra of phosphors were investigated. The effect of doping concentration of K+ ions on the upconversion (UC) luminescence of Y 2 O 3 : 10% Er3+ phosphor was examined and the possible optical transitions were discussed. The results showed that K+ ion doping not only changed the microstructure and crystallinity of the phosphors, but also enhanced its UC luminescence intensity. The Y 2 O 3 : 10% Er3+, 7% K+ phosphor exhibit the strongest UC emission intensity. Compared with the Y 2 O 3 : 10% Er3+ phosphor, the UC luminescence intensity at 563 nm and 661 nm was enhanced by 67.8 and 27.3 times for the K-codoped samples, respectively. The phosphor with the optimal doping concentration was mixed with a polymer to form a composite film, which was employed for the fabrication of near-infrared (NIR) photo-responsive detection devices. The device exhibited strong photo-current response to NIR light at 980 nm, implying that our work could inspire new design strategy for the development of NIR photo-detection devices. [ABSTRACT FROM AUTHOR]

Cesium halide lead perovskite quantum dots (QDs) have attracted great attention in the field of optoelectronics due to their excellent photoelectric characteristics. Unfortunately, the susceptibility to anion exchange, instability in air and poor water resistance of perovskite QDs hinder their practical applications. In this study, borosilicate glass doped with CsPbBr 3 QDs were prepared by traditional melt quenching and heat treatment procedures, which dramatically enhances the stability of perovskite QDs. The microstructures and luminescence properties of glass ceramics were carefully investigated. Intense green emissions were observed in the QDs doped glass under the excitation of ultraviolet light. More importantly, the photodetectors based on the CsPbBr 3 QDs doped glass possess a high on/off photocurrent ratio of 104. The dynamic linear response range is large and the response speed is fast under low bias working condition. The results suggest that CsPbBr 3 QDs doped glasses with high emission yield could find potential applications in highly efficiency photodetectors. [Display omitted] [ABSTRACT FROM AUTHOR]

• We conducted a comprehensive search for the global minimum structures of the M 2 B 16 0/- (M =Be, Mg, Ca, Sr) clusters. • The PES of the M 2 B 16 0/- (M =Be, Mg, Ca, Sr) clusters have been simulated. • It is discussed infrared absorption and Raman scattering spectra of M 2 B 16 0/- (M =Be, Mg, Ca, Sr). • The binding characteristics of cluster M 2 B 16 0/- (M =Be, Mg, Ca, Sr) are analyzed. In this work, the structure and physicochemical properties of M 2 B 16 0/- (M =Be, Mg, Ca, Sr) clusters were explored using the CALYPSO combined with DFT method. The study reveals that atomic doping leads to significant changes in the structure of B 16 , with the ground-state structure of Sr 2 B 16 exhibiting higher symmetry C 4V. The addition of extra electrons notably affects the stability of these clusters, and molecular orbital studies on the cluster system indicate that s and p orbitals dominate. Through localized orbital studies on Sr 2 B 16 clusters, the presence of hybridization between s and p orbitals enhancing the stability of the cluster was confirmed. [ABSTRACT FROM AUTHOR]

Based on density functional theory calculation, we have investigated the hydrogen storage properties of three types of Ca-decorated borophene which have been recently synthesized experimentally. It is found that Ca atoms have strong bonding strength with borophene without the problem of aggregation. The configuration of borophene has an important effect on the H 2 storage capacity. Ca-decorated borophene of S2 and S3 are promising materials system for high-capacity hydrogen storage with gravimetric hydrogen density 9.5 wt% and 7.2 wt% while that of S1 are not. Not only the polarization mechanism but also the orbital hybridization are involved in the adsorption of H 2 . The temperature and pressure have also been taken into consideration. All the hydrogen adsorbed structures of S2 and S3 are stable at room temperature under mild pressure. Our results indicate that Ca-decorated borophene of S2 and S3 structures could be expected to be promising H 2 storage materials for H 2 fuel battery. [ABSTRACT FROM AUTHOR]

Abstract: Background: Phosphatase and tensin homolog on chromosome 10 gene (PTEN) is known as a tumor-suppressor gene. Previous studies demonstrated that PTEN dysfunction affects the function of insulin. However, investigations of PTEN single nucleotide polymorphisms (SNPs) and IR-related disease associations are limited. The aim of the present study was to investigate whether its polymorphism could be involved in the risk of metabolic syndrome (MetS). Methods: The genotype frequency of PTEN −9C>G polymorphism was determined by using a Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) method in 530 subjects with MetS and 202 healthy control subjects of the Han Ethnic Chinese population in a case–control analysis. Results: The PTEN −9C>G polymorphism was not associated with MetS or its hyperglycemia, hypertension and hypertriglyceridemia components. In the control individuals aged <60years or ≥60years, the CG genotype individuals had lower insulin sensitivity than CC individuals (P <0.05). In the <60-year-old MetS group and normal glucose tolerance (NGT) subgroup, the CG individuals had lower insulin sensitivity and higher waist circumference (WC) and waist-height-ratio (WHtR) than CC individuals (P <0.05). Multiple linear regression analysis showed that the PTEN polymorphism (P =0.001) contributed independently to 4.2% (adjusted R2) of insulin sensitivity variance (estimated by Matsuda ISI), while age (P =0.004), gender (P =0.000) and the PTEN polymorphism (P =0.032) contributed independently to 5.6% (adjusted R2) of WHtR variance. Conclusions: The CG genotype of PTEN −9C>G polymorphism was not associated with MetS and some of its components as well. However, it may not only decrease insulin sensitivity in the healthy control and MetS in pre-elderly or NGT subjects, but may also increase the risk of central obesity among these MetS individuals. [Copyright &y& Elsevier]