Finite element analysis of the stability of Mason type Ⅲ radial head fracture fixed with three cross-bridge headless compression screw and locking plate / 中国骨伤

OBJECTIVE@#To compare the biomechanical stability of three cross-bridge headless compression screws and locking plates in the fixation of Mason type Ⅲ radial head fractures by finite element method.@*METHODS@#Using reverse modeling technology, the radial CT data and internal fixation data of a healthy 25-year-old male were imported into the relevant software. Three-dimensional finite element model of 3 cross-bridge headless compression screws and locking plates for MasonⅢ radial head fractures were established, and the radial head was loaded with 100 N axial loading. The maximum displacement, maximum Von Mises stress and stress distribution of the two groups were compared.@*RESULTS@#The maximum displacements of the three cross-bridge screws group and locking plate group were 0.069 mm and 0.087 mm respectively, and the Von Mises stress peaks were 18.59 MPa and 31.85 MPa respectively. The stress distribution of the three screws group was more uniform.@*CONCLUSION@#Both internal fixation methods can provide good fixation effect. CoMPared with the locking plate fixation method, the 3 cross-bridge headless compression screws fixation is more stable and the stress distribution is more uniform.

[Preparation of porous organic cage and its use as chiral stationary phase for capillary electrochromatography].

Porous organic cages (POCs) are a unique type of microporous materials composed of discrete molecules with internal cavities that are accessible to various compounds. In this study, a prismatic chiral POC with good thermochemical stability was synthesized by condensing (1R,2R)-diaminocyclohexane and 3,3',5,5'-teturonic-4,4'-biphenediol via the Schiff base reaction and characterized by proton nuclear magnetic resonance spectroscopy, infrared (IR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy. The IR spectrum of the POC revealed a strong characteristic absorption peak at 1635 cm-1, indicating that it formed imine bonds (C=N). The absorption peak at 3425 cm-1 was attributed to the stretching vibrations of -OH, the absorption peaks at 2925 and 2858 cm-1 were attributed to the stretching vibrations of N=C-H and C-H, and the absorption peaks at 1446 and 1383 cm-1 were attributed to the stretching vibrations of C=C-H and C=C in the benzene ring. High-resolution mass spectral analysis of the POC showed a molecular ion peak at m/z 1363.7228, indicating its successful synthesis. TGA was performed from 25 to 800 ℃ at a rate of 10 ℃/min, and the results of this analysis showed that the POC was stable up to approximately 300 ℃. The POC was dissolved in dichloromethane and uniformly coated on the inner wall of a quartz capillary via the dynamic coating method to prepare a capillary electrochromatographic column. The experimental results revealed that the chiral electrochromatographic column could not only resolve ofloxacin, Troger's base, 2-amino-1-butanol, and 1-phenyl-1-amyl alcohol but also separate the isomers of o-, m-, and p-toluidine and o-, m-, and p-chloroaniline, indicating its good chiral separation ability. Investigation of the optimal separation conditions for ofloxacin, Troger's base, 2-amino-1-butanol, and 1-phenyl-1-amyl alcohol revealed that the voltage, buffer solution concentration, and pH significantly affected their separation degree. In particular, the optimal separation voltage for ofloxacin, Troger's base, and 2-amino-1-butanol was 15 kV, while that for 1-phenyl-1-amyl alcohol was 17 kV. The optimal buffer concentration and pH for ofloxacin, Troger's base, 2-amino-1-butanol, and 1-phenyl-1-amyl alcohol were 0.100 mol/L and 7.5. Under optimal chromatographic conditions, the resolution values for ofloxacin, Troger's base, 2-amino-1-butanol, and 1-phenyl-1-pentanol were 1.80, 3.33, 1.69, and 1.18, respectively. The results collectively demonstrate that the prepared POC may serve as a good chiral stationary phase for capillary electrochromatography with a certain chiral resolution ability and has good application prospects in chromatographic separation.

Chiral derivatives of covalent organic framework TpBD (NH2 )2 used as stationary phases in gas chromatography.

Chiral covalent organic framework materials have many excellent properties, which have received much attention in the field of separation. Synthesized the covalent organic framework COF-TpBD (NH2 )2 modified, respectively, by L-valine trifluoroacetyl derivative, L-hydroxyproline, and (1S)-(+)-10-camphorsulfonyl chloride, three capillary columns of chiral covalent organic framework materials were obtained for gas chromatography. Those columns are able to separate some chiral compounds, positional isomers, n-alkanes, n-alcohols, aromatic hydrocarbon mixture, and Grob's reagents. They are complementary to other chiral capillary columns and are possible for potential applications.

The SACT Template: A Human Brain Diffusion Tensor Template for School-age Children / 神经科学通报·英文版

School-age children are in a specific development stage corresponding to juvenility, when the white matter of the brain experiences ongoing maturation. Diffusion-weighted magnetic resonance imaging (DWI), especially diffusion tensor imaging (DTI), is extensively used to characterize the maturation by assessing white matter properties in vivo. In the analysis of DWI data, spatial normalization is crucial for conducting inter-subject analyses or linking the individual space with the reference space. Using tensor-based registration with an appropriate diffusion tensor template presents high accuracy regarding spatial normalization. However, there is a lack of a standardized diffusion tensor template dedicated to school-age children with ongoing brain development. Here, we established the school-age children diffusion tensor (SACT) template by optimizing tensor reorientation on high-quality DTI data from a large sample of cognitively normal participants aged 6-12 years. With an age-balanced design, the SACT template represented the entire age range well by showing high similarity to the age-specific templates. Compared with the tensor template of adults, the SACT template revealed significantly higher spatial normalization accuracy and inter-subject coherence upon evaluation of subjects in two different datasets of school-age children. A practical application regarding the age associations with the normalized DTI-derived data was conducted to further compare the SACT template and the adult template. Although similar spatial patterns were found, the SACT template showed significant effects on the distributions of the statistical results, which may be related to the performance of spatial normalization. Looking forward, the SACT template could contribute to future studies of white matter development in both healthy and clinical populations. The SACT template is publicly available now ( https://figshare.com/articles/dataset/SACT_template/14071283 ).