控轧控冷工艺对冷镦铆螺钢组织和力学性能的影响

试验钢(/%:0.19C,0.17Si,0.44Mn,0.004S,0.007P,0.041Als),由60kg真空感应炉熔炼,锻成120mm×140mm坯,轧成80 mm×80mm坯,再轧成4 mm×100mm成品。试验了950℃、800℃终轧和轧后水冷、空冷对该钢组织和性能的影响。结果表明,实验钢1000℃开轧,经二道次轧制,800℃终轧,以32.33～37.50℃/s的冷却速度水冷,工艺最佳,低碳钢珠光体为89%,铁素体晶粒尺寸38 nm达到了铆螺钢ML45级别。950℃终轧,水冷,力学性能达到了ML40级别。800℃终轧,空冷钢的力学性能也能达到ML30级别。     

Comparison Between Ultrasonic Vibration-Assisted Upsetting and Conventional Upsetting

Ultrasonic vibration has been increasingly applied to metal forming processes due to its beneficial effects on the reduction of the forming force, flow stress, and friction coefficient and on the increase of the forming limit of the sheet metal. In this work, the effect of the ultrasonic vibration on the upsetting has been studied experimentally and numerically. The microstructure of the specimens processed with ultrasonic vibration-assisted upsetting (UAU) and conventional upsetting was characterized. Differences in the forming characteristics between these two methods, in terms of metal flow and forming force, were analyzed. The results of this study indicate that the use of high-intensity ultrasonic vibration can induce severe plastic deformation and improve the grain refinement efficiency. The grains of the specimens processed by the UAU process were refined to 100 to 300 nm. A deformation mechanism of the UAU process was proposed. The grain refinement mechanism was used to explain the reason why ultrasonic vibration can be used to improve the grain refinement efficiency of the upsetting process.     

SWRCH22A冷镦钢线材拉拔断裂分析

对唐钢首次试产冷镦钢SWRCH22A(Φ6.5 mm线材)使用中出现的拉拔断裂原因进行了分析,提出了相应的解决措施并收到良好效果。     

Polarography of benzotriazol and amperometric titration by means of the complex formation reaction with cupric ion (author''s transl)

One hundred and thirty patients with various heart diseases who underwent angiocardiography were studied to assess the clinical usefulness of echocardiographic aortic root diameter. The echocardiographic aortic root diameter was measured from the anterior surface of the anterior wall to the anterior surface of the posterior wall at end-diastole. A significant correlation was found between aortic root diameters measured by angiocardiograms and those by echocardiograms (r = 0.944, p less than 0.001). The aortic root diameter in normal subjects was 15 to 40 mm with a mean value of 29.0 mm. The corrected aortic root diameter by body surface area in normal subjects ranged from 10.1 to 29.5 mm/M2 with a mean value of 19.18 mm/M2. There appeared to be direct relationship between corrected aortic root diameter and the age. Echocardiography is a simple, safe, and reliable noninvasive method for estimating aortic root diameter.     

Relationship of femoral head and acetabular size to the prevalence of dislocation

Two clinical studies, one prospective randomized and one retrospective, were performed to evaluate the relationship of femoral head size and acetabular component outer diameter to the prevalence of dislocation of the modular total hip replacement. Between October 1995 and April 1996, 31 primary total hip arthroplasties in 30 patients were randomized to a femoral head diameter of 22 mm or 28 mm, for two groups of acetabular components of outer diameters of 56 mm or larger and 54 mm or smaller. Head size (22 mm) and acetabular component outer diameter (> or = 56 mm) were found to increase the risk of dislocation. From December 1984 to January 1994, 308 primary total hip arthroplasties were performed through a posterior approach by one surgeon using a modular 28 mm femoral head and one type of uncemented acetabular component. The rate of dislocation for acetabular components with an outer diameter of 62 mm or larger was increased significantly (five of 36 hips, 14%) compared with those with an outer diameter of 60 mm or smaller (11 of 272 hips, 4%).     

The effect of translation of the C1-C2 on the spinal canal

The stability of the atlantoaxial articulation depends fundamentally on the integrity of the odontoid process and the ligaments. Ligament stability mostly is maintained by two ligaments: the transverse ligament and the alar, apical ligaments. Failure of the transverse ligament can result in anterior translation of the atlas on the axis. The anteroposterior diameter of the ring of the atlas is approximately 3 cm. The spinal cord and the odontoid process are each approximately 1 cm in diameter, approximately 1/3 the diameter of the ring. According to Steel's rule of thirds, the remaining centimeter of free space allows for some degree of pathologic displacement. The current anatomic study showed that the space available for the spinal cord was limited. The sagittal diameter C1-C2 canal is 18.71 +/- 2.88 mm (excluding 10 mm thickness of the dens and 2.91 +/- 0.69 mm thickness of transverse ligament), with the spinal cord occupying 7.73 +/- 0.87 mm of the available space. Space available for spinal cord at the level of the atlas is 3.44 +/- 1.19 mm plus 1.01 +/- 0.20 mm space anterior to the cord (anterior epidural space) and 5.64 +/- 2.22 mm space posterior to the cord (posterior epidural space), which is approximately in agreement with the normal diameter by Steel's rule of thirds.     

Hepatotoxic effects of SH-reagents in human and rat hepatocyte cultures and in situ perfused rat livers

BACKGROUND: Intravascular ultrasound (IVUS) permits quantitative assessment of the lumen diameter and area of coronary arteries. The experimental study was performed to evaluate the accuracy of diameter and area measurements. METHODS AND RESULTS: Lumen quantitation (lumen diameter D and cross-sectional area A) in lucite tubes (lumen diameter 2.5 to 5.7 mm, Plexiglas) was performed using a mechanical IVUS system (HP console, 3.5 F catheter, Boston Scientific, 30 MHz). The influence of fluid type (blood, water and saline solution), fluid temperature (20 degrees C/37 degrees C), catheter to catheter variation, gain setting and ultrasound frequency (12, 20 and 30 MHz) was determined. In blood at 20 degrees C there was a constant deviation of the measured diameter from the true luminal diameter of -0.29 +/- -0.04 mm (p < 0.06). In water and saline solution at 20 degrees C the mean deviation from true diameter was -0.21 +/- -0.06 mm (p < 0.06). At 37 degrees C, the deviation in blood was greater than at 20 degrees (-0.34 +/- -0.02 mm) which is > 10% in a 3 mm tube (p < 0.06). Three of the ten catheters tested in water at 20 degrees C underestimated true diameter by more than -0.3 mm. The deviation from true diameter (5 mm tube) with varying gain settings was -0.14 mm to -0.23 mm compared to -0.19 mm at standard settings (p > 0.288). At 12 MHz diameter measured was over-estimated. The error in absolute area estimation increased with increasing diameter tested in blood at 37 degrees C (-1.21 to -2.72 mm2), whereas the relative error ([Measured Area-True Area]/True Area x 100 [%]) was more striking at smaller diameters (up to -25% in the 2.5 mm tube). CONCLUSION: Luminal diameters and areas are underestimated by this particular IVUS system. When IVUS imaging and measurements are made during coronary interventions this error should be taken into account with regard to appropriate sizing of the device and the assessment of the postprocedure result. Because systematic errors might also occur in other IVUS system (not tested in this study), it is advisable to ensure that each system is validated prior to clinical use, especially when exact measurements are required.     

Analysis of implantation-induced nail deformation and roentgen morphometric studies as the principle for an aiming device for distal interlocking nailing without roentgen image intensification

While working to develop a distal locking device, we analyzed distal nail position with reference to nail deformation and a radiographic-morphometric investigation. The amount and the direction of implant deformation in unslotted stainless steel unreamed tibial nails (Synthes) were analyzed. Measurement of implant deformation (3 translations, 3 angles) in the center of the distal transverse locking hole was performed with a 3D magnetic motion tracker system before and after nail insertion. Unreamed tibial nails (diameter 8 mm, n = 10; diameter 9 mm, n = 10) were inserted in paired human cadaver tibiae. The results showed lateral translations of -4.5 +/- 3.5 mm (mean and standard deviation, range 14.3 mm) and dorsal translations of -7.8 +/- 5.8 mm (mean and standard deviation, range 19.2 mm). Rotational deformations around the longitudinal axis of the nail were 0.3 +/- 0.7 degree (mean and standard deviation, range 2.4 degrees). The results showed, that a simple aiming arm, mounted on the proximal nail end, alone or even in combination with a large working channel (e.g. 10 mm in diameter), was not adequate to the aiming process. A radiographic-morphometric analysis was subsequently performed in 40 tibiae after experimental (n = 20) or clinical (n = 20) implantation of nails 8 mm and 9 mm in diameter. These measurements showed a relatively constant distance between the upper distal transverse hole and the anterior aspect of the tibia (average 12.3 mm and only a narrow range (7.6 mm). These data were the basis for the development of an aiming technique that exploits the relatively constant distance between the distal nail hole and the anterior aspect of the tibia. This aiming device is set at a distance of 12.3 mm from the anterior cortex, and the fine tuning is finally resolved by the use of a "working channel' 10 mm in diameter.     

MRI of the occipital cortex, red nucleus, and substantia nigra during visual aura of migraine

PURPOSE: Although radical nephrectomy is the standard treatment for localized unilateral renal cell carcinoma with a normal contralateral kidney, there is ongoing interest in the use of nephron sparing surgery or partial nephrectomy in such cases. The extent of radical surgery in such cases has also been reconsidered in view of the uncertainty regarding the malignant or benign nature. MATERIALS AND METHODS: Of 14,793 autopsies in Jena from 1985 until 1995 there were 260 renal cell carcinomas. Of the 260 renal cell carcinomas the diameter was 40 mm. or less in 104. These 104 tumors were divided into group 1-20 mm. or less (33 cases), group 2-21 to 30 mm. (28) and group 3-31 to 40 mm. (43). RESULTS: Grade 1 renal cell carcinomas decreased in frequency with increasing tumor diameter, while an opposite result was noted for grade 3. Lymph node and distant metastases were well correlated with tumor size. With an increase in tumor size the frequency of venous involvement increased as well. Significantly more multifocal malignant renal cell carcinomas were seen in tumors between 21 and 40 mm. compared to those 20 mm. or less in diameter. CONCLUSIONS: The metastatic potential and biology of these small nodules are not yet known. To lower the risk of local recurrence the results of our study suggest that nephron sparing surgery might be advisable in patients with renal cell carcinoma 20 mm. or less in diameter.     

In vitro validation of the luminal measurement of a novel catheter based moulding technique

OBJECTIVE: To investigate a modified angioplasty balloon catheter, which uses a novel balloon polymer to produce luminal moulds. DESIGN: The catheter was tested in polyurethane phantoms of diameter 1.5 to 4.0 mm. Inflations were to 1.4 atmospheres for 20 seconds at 37 degrees C. The moulds were viewed by reinflating the balloon to 0. 34 atmospheres and quantified using macrophotography and caliper measurement. RESULTS: Evidence of systematic error was found with lumen diameters 相似文献   

冷却器管道直径对大直径棒材冷却效果的影响规律

利用有限元耦合场数值模拟计算方法,对大直径棒材穿水冷却过程进行了三维非稳态数值模拟,分析了冷却器管道直径在棒材不同位置及对整体冷却效果的影响规律。模拟结果表明：在棒材整体方向上,管道直径D=220mm及D=240mm时冷却效果最好,D=350mm及D=400mm时冷却效果最差;在给定的工况条件下,棒材表层的温度在冷却过程中出现了波动,且冷却器管道直径越大波动现象越明显;棒材长度方向上温度分布不均匀。     

Natural history of abdominal aortic aneurysm detected by screening

A group of 88 patients with abdominal aortic dilation found in four ultrasonographic screening studies was followed prospectively by repeated ultrasonography. The initial aortic diameter ranged between 18 and 70 mm. In 19 patients (22 per cent) the aortic diameter exceeded 39 mm. The mean (s.e.m.) annual expansion rate of dilatations < 40 mm in diameter was 0.8 (1.2) mm; among those > or = 40 mm it was 3.3 (1.2) mm. The expansion rate increased with increasing initial diameter. Thirty-eight patients died; the overall mortality rate in the group was high in comparison with an age- and sex-matched population. One patient died after elective aneurysm surgery but none died from a ruptured aneurysm. In conclusion, in about 80 per cent of dilatations found in screening studies the aortic diameter was < 40 mm, with a low risk of rupture. One annual rescanning of an aneurysm < 35 mm in diameter is sufficient; a high overall mortality rate must be expected.     

Endoscope-assisted laparoscopic resection of the gastric wall

The early gastric carcinomas measuring 10-25 mm in diameter, macroscopically I-II/C types and benign gastric tumours are relegated to laparoscopic wedge resection of the stomach. Authors report on the use of a new endoscopic assisted--"double-lifting"--laparoscopic resection of the gastric wall, in the course of removal of an early stage gastric carcinoma (13 mm in diameter, macroscopically II/C type) and a gastric lipoma (21 mm in diameter). The advantage of this method: the affected gastric wall could be removed safely far from the lesion and all layers of the gastric wall are available for histological examination.     

镁还原罐内强化换热研究

通过分析传统球团料在还原罐内的温度分布,提出了以改进布料方式缩短硅热法炼镁还原周期的必要性.研发了一种新型炼镁料块,运用FLUENT软件对料块的传热过程进行数值模拟,分别研究了料块的高度、外缘高度、内孔直径、上下面直径、凹槽直径和凹槽个数对料块传热过程和镁产量的影响.发现当料块的高度为100 mm、外缘高度为50 mm、内径为100 mm、上下面直径为200 mm、凹槽直径为50 mm和凹槽个数为8个时,单炉镁产量最高为318 kg·h^-1,较传统球团料提高43.9%,吨镁煤气消耗量降低了30.5%.通过实验得出料块内部的温度分布与数值模拟的结果一致,说明数值模拟的模型是可靠的.     

Morphometry of the optic disc in Togolese patients with glaucoma or suspected glaucoma. Preliminary study

PURPOSE: The aim of this study was to measure morphometric parameters of the optic disc in Togolese glaucoma patients and suspects by the mean of the millimetric scale of the slit lamp and the Goldmann contact lens. MATERIAL AND METHOD: We selected 202 patients (393 eyes) with a mean age of 36.69 years +/- 15.33 (standard deviation); they were divided into 2 subgroups A (162 glaucomatous) and B (40 glaucoma suspects); direct reading of the slit lamp millimetric scale and the Goldmann contact lens was used. RESULTS: In the group A, the optic disc vertical diameter was 1.792 +/- 0.21 mm; the horizontal diameter was 1.701 +/- 0.198 mm. In the group B, vertical disc diameter was 1.700 +/- 0.262 mm; the horizontal one was 1.662 +/- 0.190 mm. The vertical cup disc diameter was 1.147 +/- 0.274 mm in the group A and 0.708 mm +/- 0.274 mm in the group B. The neuroretinal area was 1.360 +/- 0.524 mm2 in group A and 1.786 +/- 0.467 mm2 in group B. CONCLUSION: This study using millimetric scale of the slit lamp and the three mirrors Goldmann contact lens was easy, simple and useful clinically. It could be helpful in conducting quantitative studies in countries with low resources because this method is costless compared with others.     

可逆冷轧机张力系统改造中辊径及综合电流的计算与实现方法

在冷轧厂１．２ｍ冷轧机二次改造中、将张力系统由励磁控制改为力矩控制，其中的辊径及综合电流计算起郑极为重要的作用，讨论了卷径，动态电流补偿的运算过程、介绍了计算机控制框图，叙述了力矩控制系统的实现过程。     

Roentgenological study of the sagittal diameter of the cervical spinal canal in normal adult Japanese

The sagittal diameter of the cervical spinal canal on roentgenograms in normal adult Japanese aged 15 years or over, 505 males and 492 females, was investigated to define the normal distribution and lower limit. Lateral roentgenograms of cervical spinal canals were taken at a constant focus-film distance of 1.5 m. The mean +/- SD magnification coefficient was 1.17 +/- 0.02. The mean +/- SD sagittal diameters of the cervical spinal canals at each vertebral level were: C-1, 21.0 +/- 2.2 mm; C-2, 18.0 +/- 1.7 mm; C-3, 15.8 +/- 1.5 mm; C-4, 15.2 +/- 1.5 mm; C-5, 15.3 +/- 1.5 mm; C-6, 15.7 +/- 1.5 mm; and C-7, 15.9 +/- 1.4 mm. The lowest mean -2 SD values were: C-1, 16.6 mm; C-2, 14.6 mm; C-3: 12.8 mm; C-4, 12.2 mm; C-5, 12.3 mm; C-6, 12.7 mm; and C-7, 13.1 mm. The smallest diameter was at the C-4 level, but there was no significant difference between values at the C-4 and C-5 levels. Males had significantly larger diameters than females (mean difference 0.8 mm) (p < 0.01). Younger subjects had greater diameters than older subjects. The incidence of spondylotic changes was 40.1% in subjects aged 50-59 years, 57.7% in those aged 60-69 years, and 76.6% in those aged 70-79 years. Males had a higher incidence than females. Ossification of the posterior longitudinal ligament was observed in 2.1% of all subjects. This study suggests that patients with a sagittal diameter in the cervical spinal canal of less than 12 mm have a high risk of cervical myelopathy.     

Replacement of the aortic root with woven and knitted Dacron composite graft

Some of the patients with annuloaortic ectasia or Stanford type A require aortic root replacement. If conventional Bentall procedure is employed in such cases, aortic root will become a cylindrical shape totally lacking sinus of Valsalva because the procedure utilizes a straight tube. The sinuses of Valsalva support an important role in opening and closing the valvar leaflets, and opening of the coronary arteries, together with the interleaflet triangles and the sinutubular junction. In this study, we performed aortic root replacement with composite graft which consisted of two types of graft including 30 mm Knitted Dacron Graft (Gelsoft) with different dilation rates and 30 mm Woven Dacron Graft (Hemashield) as well as bioprosthesis (27 mm Carpentier-Edwards), in order to reconstruct sinus of Valsalva. Post-operative angiography revealed an excellent diastolic coronary flow, as evidenced by proximal Knitted graft of 37 mm in diameter, distal Woven graft of 30.3 mm in diameter and Doppler flow DSVR (Diastolic/Systolic Velocity Ration) of 2.2 measured at the left coronary orifice. Since it is difficult to obtain homograft at present, this procedure would be worth trying during aortic root replacement.     

High-speed, three-dimensional kinematic analysis of the normal wrist

PURPOSE: To identify the predictive risk factors for rupture of thoracoabdominal aortic aneurysms (TAA). METHODS: Thirty-one patients with TAA who did not have the indications for surgical repair of the aneurysm were selected. Inclusion criteria were maximum diameter less than 60 mm, refusal of surgical treatment, and high surgical risk. The selected patients participated in a prospective follow-up study for a median period of 47 months and underwent at least two thoracoabdominal computed tomographic scans a year to measure transverse and anteroposterior diameters. Identification of the predictive factors associated with rupture was undertaken with multivariate analysis by means of Cox regression model. RESULTS: During the study period five patients underwent elective repair, six died of unrelated causes, nine had aneurysms that ruptured (all with diameters greater than 50 mm), and 11 reached the end of the study without rupture or surgical management. Initial anteroposterior diameter and annual growth rate of the anteroposterior diameter were the variables associated with rupture of the TAA according to the multivariate statistical analysis by means of Cox regression model. CONCLUSION: We recommend elective repair for a fit patient with asymptomatic TAA with an initial anteroposterior diameter of 50 mm only when there is an annual growth rate of at least 10 mm. Patients with similar diameters but with smaller annual growth rates should be treated conservatively and undergo thoracoabdominal computed tomography every 6 months. Patients with an initial anteroposterior diameter of 60 mm and an annual growth rate of 6 mm should undergo surgical treatment. These guidelines for elective repair of TAA are based on the results of a relatively small series and have to be carefully individualized for each patient.     

RH浸渍管内径对钢液精炼与洁净度的影响

使用不同内径尺寸的RH浸渍管进行工业生产试验,试验结果表明:浸渍管内径越大,钢液脱碳、脱氢速率越高、浸渍管耐材侵蚀率降低、洁净度提高.浸渍管内径由450 mm扩大到510 mm,钢液初始碳质量分数0.05％ 经过RH深脱碳至0.01％ 以下,时间缩短了8 min,效率提高了61.5％;经过真空循环脱气后,钢液氢质量分数...