砷在氮化-碳化法制备超细碳化钨粉过程中的细化机理

为了简化工艺制备超细WC粉末,在伸钨酸铵前驱体中添加一定量的As元素,采用氮化-碳化法系统研究As在超细WC粉制备过程中的作用机理。结果表明,当碳化温度均为1400℃,氮化温度从500℃升高到600℃,As含量从0增加到0.3%(质量分数)时,所制备的WC粉平均粒径从2.23μm减小到0.22μm,颗粒均匀性显著提高。As元素在氮化产物中以W_(2)O_(3)(AsO_(4))_(2)的形式存在,且容易在氮化产物(NH_(4))_(0.42)WC_(3)和WN表面富集或分布于两相之间,阻碍碳化过程中WC晶粒的长大,从而制备超细WC粉。

Anatomy and clinical application of suprascapular nerve to accessory nerve transfer

BACKGROUND Loss of motor function in the trapezius muscle is one complication of radical neck dissection after cutting the accessory nerve(AN) during surgery.Nerve repair is an effective method to restore trapezius muscle function,and includes neurolysis,direct suture,and nerve grafting.The suprascapular nerve(SCN) and AN are next to each other in position.The function of the AN and SCN in shoulder elevation and abduction movement is synergistic.SCN might be considered by surgeons for AN reanimation.AIM To obtain anatomical and clinical data for partial suprascapular nerve-to-AN transfer.METHODS Ten sides of cadavers perfused with formalin were obtained from the Department of Human Anatomy,Histology and Embryology,Peking University Health Science Center.The SCN(n = 10) and AN(n = 10) were carefully dissected in the posterior triangle of the neck,and the trapezius muscle was dissected to fully display the accessory nerve.The length of the SCN from the origin of the brachial plexus(a point) to the scapular notch(b point) and the distance of the SCN from the origin point(a point) to the point(c point) where the AN entered the border of the trapezius muscle were measured.The length and branches of the AN in the trapezius muscle were measured.A female patient aged 55 years underwent surgery for partial SCN to AN transfer at Department of Oral and Maxillofacial Surgery,Peking University School and Hospital of Stomatology.The patient suffered from recurrent upper gingival cancer.Radical neck dissection was performed on the right side,and the right AN was removed at the intersection between the nerve and the posterior border of the SCM muscle.One-third of the diameter of the SCN was cut off,and combined epineurial and perineurial sutures were applied between the distal end of the cut-off fascicles of the SCN and the proximal end of the AN without tension.Both subjective and objective evaluations were performed before,three months after,and nine months after surgery.For the subjective evaluation,the questionnaire included the Neck Dissection Impairment Index(NDII) and the Constant Shoulder Scale.Electromyography was used for the objective examination.Data were analyzed using t tests with SPSS 19.0 software to determine the relationship between the length of the SCN and the linear distance.A P value of < 0.05 was considered as statistically significant.RESULTS The whole length of the AN in the trapezius muscle was 16.89 cm.The average numbers of branches distributed in the descending,horizontal and ascending portions were 3.8,2.6 and 2.2,respectively.The diameter of the AN was 1.94 mm at the anterior border of the trapezius.The length of the suprascapular nerve from the origin of the brachial plexus to the scapular notch was longer than the distance of the suprascapular nerve from the origin point to the point where the accessory nerve entered the upper edge of the trapezius muscle.The amplitude of trapezius muscle electromyography indicated that both the horizontal and ascending portions of the trapezius muscle on the right side had better function than the left side nine months after surgery.The results showed that the right-sided supraspinatus and infraspinatus muscles did not lose more function than the left side.CONCLUSION Based on anatomical data and clinical application,partial suprascapular nerve-to-AN transfer could be achieved and may improve innervation of the affected trapezius muscle after radical neck dissection.

Evolution of transmaxillary approach to tumors in pterygopalatine fossa and infratemporal fossa:anatomic simulation and clinical practice

Background:The endoscopic transnasal approach has been proven to have advantages on the removal of the tumors in pterygopalatine fossa(PPF)and infratemporal fossa(ITF).Herein,this study aimed to describe a modified approach for resection of the tumors in these areas,both in cadaveric specimen and clinical patients.Methods:The 20 adult cadaveric specimens and five patients with tumors in PPF and ITF were enrolled in this study.For the cadaveric specimens,ten were simulated anterior transmaxillary approach and ten were performed modified endoscopic transnasal transmaxillary approach.The exposure areas were compared between two groups and main anatomic structure were measured.Surgery was operated in the five patients with tumors of PPF and ITF to verify the experience from the anatomy.Perioperative management,intraoperative findings and postoperative complications were recorded and analyzed.Results:The modified endoscopic transnasal transmaxillary approach provided as enough surgical exposure and high operability to the PPF and ITF as the anterior transmaxillary approach did.The diameter of maxillary artery in the PPF was 3.77±0.78 mm(range:2.06-4.82mm),the diameter of middle meningeal artery in the ITF was 2.79±0.61 mm(range:1.54-3.78 mm).Four patients who suffered schwannoma got total removal and one of adenocystic carcinoma got subtotal removal.The main complications were facial numbness and pericoronitis of the wisdom tooth.No permanent complication was found.Conclusions:With the widespread use of neuroendoscopy,the modified endoscopic transnasal transmaxillary approach is feasible and effective for the resection of tumors located in PPF and ITF,which has significant advantages on less trauma and complications to the patients.