Electrochemical aspects of the formation of Bi2Te3 thin film via the route of ECALE

A Bi₂Te₃ VA–VIA group compound thin film was prepared via the route of electrochemical atomic layer epitaxy in this paper. The dependence of thin film formation on the electrochemical conditions (such as deposition potential control, supporting electrolyte and substrate) was studied, and the formation process of Bi₂Te₃ film was determined. The results show that Bi upd on Pt occurs at more negative potential in a HNO₃ supporting electrolyte than in a HClO₄ supporting electrolyte, and the Te upd peak moves to a more negative potential in HClO₄ supporting electrolyte solution than that in HNO₃ solution; Both Te and Bi upd on an Ag substrate occur at more negative potentials than that on a Pt substrate. In order to reach steady state deposition, a potential adjustment is necessary for the first 30 or more cycles of each component. After deposition of this initial ‘buffer layer’, the potentials can be kept constant for the remaining cycles. The effect of the slope of the shift of potential used to deposit the first 30 atomic layers of Bi and Te on the deposit has also been investigated. The deposit exhibits a two phase mixture of excess elemental Bi and Bi₂Te₃ compound when the slope is larger than ?4 mV/p (p indicates per cycle); a single-phase Bi₂Te₃ compound was obtained at a slope of ?6 mV/p, and Bi₄Te₃ compound also appears in the deposit along with Bi₂Te₃ when the slope is decreased to a more negative value of ?10 mV/p.     

Identification of a C-shaped canal system in mandibular second molars-part II: the effect of bone image superimposition and intraradicular contrast medium on radiograph interpretation

The purpose of this study was to investigate the effect of image superimposition from surrounding alveolar bone and intraradicular contrast medium on radiographic interpretation of a C-shaped canal system in mandibular second molars. Thirty mandibular second molars with fused roots were collected and stored in 10% formalin solution. After being scanned by microcomputed tomography and reconstructed, the buccal-lingual radiographs of each tooth were taken with or without intraradicular contrast medium and mandibular bony plates. The number of mesial and distal canals in the coronal-to-middle canal portion and the canal number in the apical 4-mm area were recorded. The buccal-lingual and three-dimensional view of reconstructed canal images were used to evaluate the accuracy of radiograph reading. The results were subjected to the Friedman and chi-square test. The results showed that without intraradicular contrast medium, the bone superimposition could decrease the accuracy of canal recognition significantly (p < 0.001), especially in the apical area. When contrast medium was in canals, the canal reading seemed not to be affected by the bone superimposition (p > 0.05). Based on these findings, the intraradicular contrast medium could increase the accuracy of canal recognition of a C-shaped canal system in mandibular second molars despite the bone image superimposition, especially in the detection of continuous C-shaped canals and the canals in the apical area.     

Leakage along warm gutta-percha fillings in the apical canals of curved roots

The aim of this study was to investigate the leakage along the apical portion of warm gutta-percha obturated curved canals. Human mandibular premolars with single, curved (21 degrees-40 degrees) canals were prepared using the Lightspeed technique. Two groups of prepared canals, matched according to curvature and prevalence of apical transportation, were obturated by two techniques. Coronal gutta-percha was removed immediately after root obturation was completed to simulate the procedure for post space preparation. Leakage along the apical 3 mm of root filling was measured with a fluid transport device. Vertical condensation of warm gutta-percha and Pulp Canal Sealer provided less leakage than Thermafil plastic obturators and AH26 sealer (P = 0.002).     

五倍子水提取物去除根管内玷污层的扫描电镜观察

目的:观察五倍子对根管内玷污层的去除效果。方法:72个离体单根牙随机分为9组,冲洗液为五倍子组(分别为200、100、50、25、12.5、6.25mg/mL)、30mL/L过氧化氢液加生理盐水组、170g/LEDTA加52.5g/LNaOCl组(阳性对照)、双蒸水组(阴性对照)。根管预备后用各冲洗液冲洗,选根中部分进行扫描电镜观察。样本分为10个区,分别评分,结果进行统计学分析。结果:170g/LEDTA加52.5g/LNaOCl组去除玷污层效果最好,但管周牙本质有过度脱矿现象。25、50、100、200mg/mL五倍子组去除玷污层的效果较好,其去除玷污层的能力随浓度增加而增大,且牙本质小管有缩小的现象,当大于50mg/mL时牙本质小管被堵塞。30mL/L过氧化氢液加生理盐水组和双蒸水组不能去除玷污层。结论:大于6.25mg/mL的五倍子水提取物有去除玷污层的作用,随浓度增大,牙本质小管缩小并出现堵塞。     

Mandibular distraction osteogenesis reconstructed the upper airway in a case of Melnick�CNeedles syndrome

Introduction

We report a 16-year-old female with Melnick?CNeedles syndrome complicated with severe obstructive sleep apnea?Chypoxia syndrome.

Clinical report

An overnight sleep study demonstrated that the patient had severe obstructive sleep apnea with an apnea?Chypopnea index of 95/h. The lowest oxygen saturation was only 34%. The distraction osteogenesis technique was used to lengthen her mandible for the reconstruction of her upper airway.

Result and Discussion

Postoperative panorex showed that the bilateral body of her mandible had been distracted about 16?mm singulorumly in the end of our distraction. Lateral radiograph revealed that the diameter of oral pharynx widen nearly 5?mm. The patient recovered after the upper airway reconstruction.     

A Novel Prefabricated Grid for Guided Endodontic Microsurgery

Introduction

This study aimed to introduce a novel method using cone-beam computed tomographic (CBCT) imaging and prefabricated grids to guide apical access during endodontic microsurgery and to compare its accuracy with that of the nonguided method.

CGF-1型复合体抑龋能力的研究

目的 :评价CGF - 1型复合体的抑龋能力。方法 :新拔除的磨牙 40个 ,于釉牙骨质交界处制洞(4mm× 2mm× 1.5mm) ,分别用CGF - 1型复合体、Dyract复合体、FujiⅠ玻璃离子、Durafill复合树脂充填 ,致龋酸胶(pH =4)中浸泡 2 1d后 ,偏光镜下观察充填材料周围类龋损的形成情况。结果 :充填体周围类龋损呈矩形 ,呈正双折射改变 ,CGF - 1型复合体周围类龋损在釉质和牙本质 -牙骨质的平均深度大于FujiⅠ玻璃离子和Dyract复合体 ,但较Durafill复合树脂小。结论 :CGF - 1型复合体具有一定的抑龋能力但较FujiⅠ玻璃离子和Dyract复合体弱。     

义齿塑料基托热压灌注成型新工艺—颜色稳定性的比较研究

目的：分析比较成型后的基托塑料可能发生的变色。方法：对不同粉、液比例灌注成型的基托塑料和常规模压成型的基托塑料，用分光测色仪观察颜色稳定性。结果：粉、液以２∶１体积比灌注成型的义齿基托，表面平整光滑，色调、饱和度与常规模压成型的义齿基托相同，而其表面可抛光性优于常规法。结论：２种方法成型的义齿基托对紫外线的敏感性无显著性差异。