螺旋断层治疗设备多叶准直器故障分析

目的 通过对螺旋断层治疗设备二进制气动多叶准直器故障现象及处理方法的分析,总结相关维修经验,达到准确判断故障部件,缩短停机时间,提高开机率的目的。方法 对螺旋断层治疗设备48个月的多叶准直器维修情况进行统计和分析,总结出多叶准直器常见的故障部件、故障原因及处理方法。结果 在48个月内,设备共出现多叶准直器故障20次,空气压缩机11次,位置验证板4次,叶片驱动器2次,叶片缓冲阀2次,叶片位置验证杆滑脱1次。多叶准直器故障与高压气体湿度有很大关系,设备出束时间对多叶准直器部分部件使用寿命也有很大影响。结论 螺旋断层治疗设备多叶准直器结构复杂,高强度工作增加了其故障率,高压气体湿度影响设备多叶准直器的正常运行,通过总结多叶准直器维修经验可初步判断故障原因,确定故障部件,达到缩短停机时间、提高开机率的目的。     

Corneal flap thickness with the Moria M2™ microkeratome and Med‐Logics calibrated LASIK blades

Purpose: This study aimed to compare and study potential factors that affect the accuracy of corneal flap thickness created in laser‐assisted in situ keratomileusis (LASIK) using the Moria model 2 (M2?) head 130 microkeratome with the Med‐Logics calibrated LASIK blades Minus 20 (ML –20) and Minus 30 (ML –30). Methods: Corneal thickness in 200 (164 myopic and 36 hyperopic) eyes (100 patients) was measured by ultrasonic pachymetry preoperatively and intraoperatively after flap cutting. A total of 100 eyes were treated with the ML –20 and 100 with the ML –30. The right eye was operated before the left eye in each patient, using the same blade. In an additional group of 40 eyes, the left eye was operated first. Results: Mean corneal flap thickness using the ML –20 blade for an intended flap thickness of 140 μm was 129.1 μm (standard deviation [SD] 15.6, range 104–165 μm) in right eyes and 111.5 μm (SD 14.5, range 78–144 μm) in left eyes. Mean corneal flap thickness using the ML –30 blade for an intended flap thickness of 130 μm was 127.1 μm (SD 16.6, range 90–168 μm) in right eyes and 109.9 μm (SD 16.8, range 72–149 μm) in left eyes. Conclusions: Both microkeratome blade types cut thinner flaps than were intended. There was substantial variation in flap thickness. The first flap to be cut with a particular blade was considerably thicker than the second flap cut with the same blade. Based on these data, we recommend the use of disposable single‐use microkeratomes rather than these ML blades.     

Influence of the Geometrical Features of the Cutting Edges of Abrasive Grains on the Removal Efficiency of the Ti6Al4V Titanium Alloy

The shape of the cutting blades of the abrasive grains has an influence on the material separation process in the machining zone. The paper analyzes the influence of the geometrical parameters of the abrasive grains (rake angle γ, apex angle ε, opening angle α), as well as width b_z and length b_b of the cutting zone on the material removal efficiency. The material removal efficiency was determined taking into account the volume of the removed material V_G and the volume of lateral piles-up V_R. The analyses were carried out on the basis of the results of experimental and simulations using the finite element method. The relationship between the selected geometric parameters characterizing the cutting zone and the coefficient characterizing the efficiency of the material removal process was determined. A strong influence of the opening angle α as well as the width b_z and length b_b of the cutting zone on the material removal process by abrasive grain was demonstrated. It was observed that the wide cutting edge, and thus the large opening angle α of the grain, reduced the size of the pile-ups and more effectively removed the chip material.     

Suboptimal controller design for active control of circular saw vibrations

A circular saw in operation can have an instability phenomenon which is characterized by a large amplitude and operation speed-dependent vibration. In this paper, a method of suppressing such unstable motion is presented. An optimal output feedback control scheme is adopted, and only the output variables available from sensors are used. A truncated vibrational mode model is used to formulate the saw dynamics. This model incorporates the forces due to the actuators. Since the performance of controlling the saw motion depends greatly upon spatial locations of both actuators and sensors, their locations are optimally determined with respect to a prescribed performance index representing the vibrating system energy. A two-mode simulation of a saw is made to illustrate the effectiveness of the control scheme. The results show that this proposed design method stabilizes the otherwise unstable motion of the saw and also requires a very short controlling time for vibration suppression.     

针刀法治疗跟痛症22例临床分析

目的：探讨跟痛症发病机理及针刀法治疗疗效。方法：用针刀在跟骨刺基底部，将跖长韧带自附着处切断，并于足弓处切断跖腱膜，结果：22例经针刀法治疗一次后跟痛症状消失，随访半至一年，总有效率95．46％，结论：跟骨刺不是引起跟痛症的主要原因，而是由于附着于跟骨结节上的跖长韧带及跖腱膜的反复受伤，造成粘连，水肿，筋膜挛缩及无菌性炎症所致，经针刀彻底切断，松解跖长韧带及跖腱膜，可消除跟痛症。     

叶状牙种植体在上前牙种植中的临床研究

用国产CDIC叶状牙种植体及配套器械 ,瑞士产CH -9400型牙种植机 ,对身体健康 ,无全身系统性疾病的43名患者 ,按常规操作植入牙种植体。部分种植体在模板引导下定位 ,部分于唇侧骨倒凹区植入可降解的α -磷酸三钙。术后0～2周暂冠修复 ,3～6月永久修复。观察时间近3年 ,除一枚种植体松动而拔除外 ,其余牙种植体均稳固。其中5枚牙种植体在暂冠修复后有I°松动 ,经调后半年至一年稳固 ,39枚种植体上已永久修复者均能正常行使功能。说明叶状牙种植体在上前牙缺失种植修复中有其独特的优势     

Aortotomy and Endarterectomy of the Ascending Aorta for Aortic Valve Replacement in a Patient with Porcelain Aorta

Patients with a calcified “porcelain” aorta may also have aortic valve stenosis, necessitating aortic valve replacement to prevent cerebral complications. However, a porcelain aorta can be difficult to open, and ascending aorta repair sutures are almost impossible to insert in a calcified plate. We devised a method of aortotomy using a small oscillating saw, which allowed us to incise the aortic wall cleanly without destruction or the formation of debris. After partial endarterectomy of the calcified plate with aortotomy, closure of the aorta was buttressed with bovine pericardium. During the endarterectomy, we used an elevator designed for hand surgery to exfoliate the calcified intimal plate.     

Management of Paget's Disease of the Calcaneum

The calcaneum is not the most common site for Paget's disease of bone, with only a few reports of monostotic involvement. We present 2 cases of Paget's disease of bone affecting the calcaneus, present an overview of the published data, and describe our management of these interesting cases.