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We report the magnetic and optical properties of Fe2(HPO3)3 ⋅ 4H2O. By combined magnetic susceptibility and specific heat measurements, we find two antiferromagnetic (AFM) transitions (TN1=9 K, TN2=5 K) which originate from the AFM exchange interactions mediated by the (HPO3)2− anions. Compared with the non‐hydrated compound Fe2(HPO3)3, the magnetic interaction strength and ordering temperature of Fe2(HPO3)3 ⋅ 4H2O are both reduced by a factor of ~2. Through density functional theory (DFT) analysis we find almost degenerate AFM states in Fe2(HPO3)3 ⋅ 4H2O which are close in energy. The competition of these AFM states might lead to the two successive AFM phase transitions at low temperature. The low ordering temperature as well as competing AFM states both imply frustrated magnetism in Fe2(HPO3)3 ⋅ 4H2O, probably originating from the complex competing AFM interactions. The optical properties of Fe2(HPO3)3 ⋅ 4H2O are also investigated by photoluminescence and infrared spectroscopies. [ABSTRACT FROM AUTHOR]

Using Born–Oppenheimer ab initio molecular dynamics (BOAIMD) simulations, the high-density water (HDW) and low-density water (LDW) structures based on SCAN meta-GGA are compared with those based on PBE GGA. Compared with Car–Parrinello ab initio molecular dynamics (CPAIMD) simulations, BOAIMD simulations can produce more accurate results because no fictitious electron mass is introduced. At each state point, our simulations continue for 100 ps after the system reached equilibrium, which is the longest ab initio simulations of liquid water reported so far and can ensure an accurate statistical average. The influence of the size effect and nuclear quantum effect on structure is not considered in the present work, but only that of two different functionals on the structure is discussed. It is found that, in HDW, just as shown using CPAIMD simulations, the SCAN-based hydrogen-bonds (HBs) are more flexible than the PBE-based ones, which makes the structure based on SCAN obviously closer to the experimental results than that based on PBE. However, it is not the case in LDW, and the difference between the results based on these two functionals is very small. [ABSTRACT FROM AUTHOR]

Telomere length was found to be associated with omethoate exposure and polymorphisms in certain genes among occupational workers. However, whether the polymorphisms in telomere-binding protein genes influence telomere length remains unclear. To explore the correlation between telomere length and polymorphisms in telomere-binding protein genes, telomere length in peripheral blood leukocytes was determined by real-time quantitative polymerase chain reaction in 180 omethoate-exposed workers and 115 healthy controls. Polymorphisms in 10 pairs of alleles were detected using flight mass spectrometry or polymerase chain reaction–restriction fragment length polymorphism technique. The results showed that individuals with GG genotype in TRF1 rs3863242 had longer telomere lengths than those with AG + AA genotype in the control group (p = 0.005). The multiple regression analysis suggested that both omethoate exposure (b = 0.526, p < 0.001) and TRF1 rs3863242 GG (b = 0.220, p = 0.002) were related to a longer telomere length. In conclusion, GG genotype in TRF1 rs3863242 is linked to prolongation of telomere length, and individuals with GG genotype are recommended to strengthen health protection in a Chinese occupational omethoate-exposed population. [ABSTRACT FROM AUTHOR]

Based on the newly developed SCAN meta-GGA and the widely used PBE-GGA functionals, ab initio molecular dynamics are performed on water. It is proved that, although the SCAN meta-GGA is not as good as the TIP4P/2005 model potential in describing the equation of state of water, it is much better than the PBE-GGA, the ST2 model potential, and ab initio trained neural network potentials. Moreover, the SCAN meta-GGA predicts a first-order liquid–liquid transition from high- to low-density water at negative pressure, in which the structures are qualitatively consistent with experimental observations, and the spinodal point of high-density water is very close to Speedy's stability limit line. [ABSTRACT FROM AUTHOR]

Omethoate is an organophosphorus pesticide that poses a major health hazard, especially DNA damage. The purpose of this study was to investigate the factors affecting telomere length in workers exposed to omethoate by analyzing the interaction between cell cycle gene polymorphism and environmental factors. The exposure group consisted of 118 workers exposed to omethoate for 8–10 years, the control group comprised 115 healthy people without occupational toxicant exposure history. The telomere length of genomic DNA from peripheral blood leucocyte was determined with real-time PCR. Polymerase chain reaction and restriction fragment length polymorphism was used to detect the polymorphisms in p53, p21 and MDM2 gene. The telomere length in the (CA + AA) genotypes for p21 rs1801270 polymorphism was longer than that in the CC genotype in control group (P = 0.015). The generalized linear model analysis indicated the interaction of the p21 rs1801270 polymorphic (CA + AA) genotypes and smoking has a significant effect on telomere length (β = −0.258, P = 0.085). The prolongation of telomere length in omethoate-exposed workers was associated with genotypes (CA + AA) of p21 rs1801270, and interactions of (CA + AA) genotypes and smoking factor. [ABSTRACT FROM AUTHOR]

As to the prototypical realization of the famous Mermin–Wagner theorem, two dimensional Heisenberg ferromagnets (2D HFMs) are expected to have no static order at finite temperatures [N. D. Mermin and H. Wagner, Phys. Rev. Lett., 1966, 17, 1133]. However, a perfect 2D HFM with negligible inter-layer exchange is still lacking, impeding studies of its novel properties. Here we report the synthesis, structure, and properties of a new metal–organic single crystal piperazinediium tetrabromocuprate ((C4H12N2)CuBr4, PTBC). The Cu2+ spins form perfect 2D layers which are well separated by organic ligands. Single crystal electron paramagnetic resonance (EPR) and magnetic susceptibility measurements reveal that PTBC is a highly isotropic Heisenberg ferromagnet with a strong intra-layer ferromagnetic exchange J/kB = 31.34(6) K (H‖ab) and 36.54(17) K (H⊥ab). However, it does not order down to 2 K, indicating the negligible inter-layer exchange J′ and ultra-small R ratio (R = J′/J) below 6 × 10−28. This is the smallest R ratio ever reported for a 2D HFM. These results imply that PTBC is by far the best realization of a 2D HFM system. Moreover, the typical single crystal size is as large as 20 mm × 20 mm × 3 mm, making it suitable for studying the magnetic dynamics of a 2D HFM by probes such as inelastic neutron scattering. [ABSTRACT FROM AUTHOR]