Revisiting calculation of tilt angles for double-tilt sample holders in transmission electron microscopes.

We revisited the formula related to the overall tilt angle of a specimen using a side-entry double-tilt sample holder in a transmission electron microscope. Initially, we examined existing formulas in the literature for calculating the overall tilt angle. Subsequently, a new formula was derived, proven to better account for the actions of the double-tilt holder, thereby providing improved accuracy in the calculation. This newly derived formula has been implemented in the Landyne software suite. Furthermore, we demonstrated the accuracy of the new formula through examples. RESEARCH HIGHLIGHTS: A new formula has been derived to calculate overall tilt angles for side-entry double-tilt holders in TEM.

A modulated structure derived from the XA-type Mn2RuSn Heusler compound.

A modulated structure derived from the inverse Heusler phase (the XA-type and the disordered variant L21B-type) has been observed in rapidly quenched Mn2RuSn ribbons. The powder X-ray diffraction pattern of the quenched ribbons can be indexed as an L21B-type structure. Electron diffraction patterns of the new structure mostly resemble those of the XA-type (and the disordered variant L21B-type) structure and additional reflections with denser spacing indicate a long periodicity. Orthogonal domains of the modulated structure were revealed by a selected-area electron diffraction pattern and the corresponding dark-field transmission electron microscopy images. The structure was further studied by the crystallographic analysis of high-resolution transmission electron microscopy images. A model for the modulated structure has been proposed to interpret the experimental results.

[Correlation between highest point of greater trochanter and the ideal entry point for antegrade femoral nailing by three-dimensional images].

OBJECTIVE: To provide reference of the ideal entry point for antegrade femoral nailing according to analysis correlation between highest point of greater trochanter and the middle line of the medullary cavity in adults by three-dimensional images. METHODS: From January 2016 to January 2017, 107 adults who underwent continuous computed tomography (CT) scans were ultimately enrolled, including 64 males and 43 females with an average age of (51.7±16.4) years old;54 patients on the left side and 53 patients on the right side. Three-dimensional images were built by using image-processing software (Volume Viewer) to reconstruct geometry of cortex and medullary canal. All people weregrouped according to different femoral greater trochanter morphology, such as anterior apex (AA), posterior apex (PA), middle apex (MA) and none apex (NA). Forwards inclination was adjusted to apparent neck shaft angle (ANSA) and true neck shaft angle (TNSA) on the coronal and saggittal view, recorded as C-ANSA, C-TNSA, S-ANSA, S-TNSA respectively, vertical distance from the middle line of femur medullary cavity to the highest point of greater trochanter of femur on the 4 positions were measured and performed statistical analysis, multiple linear regression was applied to analysis relationship between clinical data and VD value. RESULTS: (1)Comparison of VD value among 4 groups on the 4 positions, there were no difference in VD value between AA and MA groups on the S-ANSA position;and no differences in VD value among AA, MA and NA groups on the C-ANSA and C-TNSA position. (2)There were differences in VD value among AA, MA and NA groups on the sagittal plane;while had difference in VD value between PA and NA group on the coronal plane. (3)Prediction equation of VD value on S-ANSA and S-TNSA position by multiple linear regression showed R=0.343, F=3.409, P=0.012 on the S-ANSA position;R=0.317, F=2.846, P=0.028 on the S-TNSA position; neck shaft angle and sex were risk factors of VD value on the sagittal plane, while no difference in VD value on the coronal position. CONCLUSION: (1)When indentify insertion point in adult femoral nail according to the highest point of greater trochanter as anatomic landmark, the morphology of greater trochanter of femur should be distinguished to certain observation position, then evaluate migration before and after on the sagttial plane and lateral offset on the coronal plane. (2)Migration before and after on the sagttial plane is increase with increase of neck shaft angle, and the degree of migration of female before and after is less than that of male.