Nonaffine Strains Control Ductility of Metallic Glasses.

The origin of limited plasticity in metallic glasses is elusive, with no apparent link to their atomic structure. We propose that the response of the glassy structure to applied stress, not the original structure itself, provides a gauge to predict the degree of plasticity. We carried out high-energy x-ray diffraction on various bulk metallic glasses (BMGs) under uniaxial compression within the elastic limit and evaluated the anisotropic pair distribution function. We show that the extent of local deviation from the affine (uniform) deformation in the elastic regime is strongly correlated with the plastic behavior of BMGs beyond yield, across chemical compositions and sample history. The results suggest that the propensity for collective local atomic rearrangements under stress promotes plasticity.

Efficacy of radiofrequency catheter ablation for premature ventricular contractions in children.

PURPOSE: This study evaluated the efficacy and safety of transcatheter radiofrequency ablation (RFCA) in treating ventricular premature contractions (PVCs) in children, summarized the countermeasures during intraoperative ventricular fibrillation (VF), and improved the safety of ventricular premature treatment. METHODS: A retrospective analysis was conducted on 75 children with PVCs who received RFCA in the Second Affiliated Hospital of Wenzhou Medical University from January 2010 to April 2019. Data including age, sex, body weight, ejection fraction, left ventricular end diastolic diameter, burden and number of PVCs/24 h, origin of PVCs, and its complications were collected. Paired t test was used to compare changes in cardiac function before and after surgery. RESULTS: Among the 75 cases treated with RFCA, 68 were successfully ablated, giving a success rate of 90.67%. After ablation, the left ventricular ejection fraction (LVEF) of the children was 69.13 ± 3.81%, which was significantly higher than that before surgery (69.13 ± 3.81% vs. 66.21 ± 3.22%, P = 0.012). One of the patients experienced VF during the operation, with no other complications. The initial locus of origin was the anterior septum of the right ventricular outflow tract, but VF occurred during the ablation process. Mean follow-up time was 39 ± 33 months, with two recurrent cases (2.94%). CONCLUSIONS: Performing RFCA in children is safe and effective, with a low recurrence rate and few complications. VF is not an indication to cease surgery; the key to eliminating complications is repositioning the catheter and finding a more accurate origin point.

Application of RW-splint in clinical diagnosis of classⅡ1 malocclusion patients / 口腔疾病防治

Objective @# To investigate whether the RW-splint could be used to guide or determine the CR position of the lower jaw so as to provide help for the later diagnostic design.@*Methods@#20 class ⅡⅠ malocclusion patients were recruited in orthodontic department of Foshan Stomatological Hospital. They were treated by RW-splint for half a year before orthodontic treatment. The overjet of anterior teeth were recorded before and after treatment. @*Results @#The overjet of anterior teeth was (6.792 ± 0.795) mm before treatment and (7.720 ± 0.930) mm after half a year's treatment. The overjet of anterior teeth had significant difference (t=6.319, P <0.01). The overjet change of anterior teeth between before treatment and half year after treatment was (0.928 ± 0.657) mm. @* Conclusion @#The RW-splint wearing before treatment can be used to guide or determine the mandible in the CR position.

[Clinical application of micro-implant anchorage for treatment of scissors bite on one-side posterior teeth].

OBJECTIVE: To evaluate the efficiency of micro-implant anchorage (MIA) for posterior teeth intruded and the result of the treatment of scissors bite on one-side posterior teeth. METHODS: The study included 3 females and 1 male. All the overextruding upper posterior teeth were intruded by the MIA. The micro-implant screws were inserted into the buccal and lingual alveolar hone of the maxillary posterior teeth or the buccal alveolar hone of mandibular posterior teeth. About 0.833 N force was used to intrude the overgrowthing upper posterior teeth, and about 0.559 N force was used to draw buecally the low posterior teeth tilting lingually. RESULTS: The overextruding upper posterior teeth were intruded 2.0 mm on average, the low posterior teeth tilting lingually were upreared buccally. All the MIA screws kept stable during the treatment, but there was a slight inflammation around the implant screws. CONCLUSION: MIA could be used as an efficient method to correct scissors bite on one-side posterior teeth with intruding overgrowth upper posterior teeth, or uprearing buccally the tilting low posterior teeth.

[Prognosis of utility of modified supracrestal fiberotomy and contact point reproximation in the treatment of anterior segment crowding].

OBJECTIVE: The aim of this study was to evaluate quantitatively the effectiveness and feasibility of the modified supracrestal fiberotomy (MSF) and the contact point reproximation (CPR) in decreasing the relapse of anterior segments rotating and/or crowding after orthodontic treatment. METHODS: A total of 129 patients with crowding and/or rotated anterior teeth were selected for this study, and the average age was 13.07 years (54 males, 75 females). The modified supracrestal fiberotomy was performed on the anterior segments of patients in the experimental group (48 cases). After the anterior teeth were aligned, 23 of the 48 cases received a further treatment of the contact point reproximation on the anterior segments (the subgroup of MSF + CPR), and the other 25 subjects did not receive this treatment (the subgroup of MSF). The control group consisted of 81 cases. All cases wore Hawley retainers for 1.8 to 2.3 years, and all the patients were revisited 2.4 years postretention. The maxillary and mandibular dental models of all the patients were taken before treatment (T1), at the end of the treatment (T2) and 2.4 years postretention (T3). RESULTS: The relapse rate in the experimental group [(T3-T2)/T1 x 100%] was 21.6%, lower than that in the control group (P < 0.001). The relapse rate of mandible in the subgroup of MSF + CPR was 6.56% lower than that of the subgroup of MSF (P < 0.05). But the relapse rate of maxillary in the subgroups of MSF + CPR was similar as that of the subgroup of MSF (P > 0.05). CONCLUSION: The modified supracrestal fiberotomy can effectively alleviate relapse after orthodontic treatment of the crowding and/or rotation of anterior teeth. The treatment combining MSF and CPR can help maintain the stability of post-retention of mandibular anterior teeth.