穿孔机导盘粘钢研究

导盘粘钢是一个涉及许多可变因素的复杂问题，选择导盘冷却水、导盘和轧辊在轧制方向的分速度之比、管坯加热温度和高压水除鳞等因素做正交试验，确定了现有生产条件下的最佳工艺参数和各因素对导盘粘钢影响的主次顺序，在实际生产中收到了较好的效果。     

穿孔机钢导盘粘钢原因分析及控制

导盘粘钢是造成穿孔机组停机的主要故障之一。从穿孔工具、穿孔孔型参数调整、穿孔速度制度、管坯加热制度、以及导盘冷却效果等五个方面分析了造成导盘粘钢的原因,并提出相应的控制措施,为生产中有效降低导盘粘钢故障时间提供了依据,并取得良好效果。     

1150斜轧穿孔机迪塞尔导盘结瘤产生的原因及预防

本文论述了宝钢φ1150斜轧穿孔机迪塞尔导盘结瘤产生的原因及预防,并对有关机理进行了探讨,这对同类机组减少导盘结瘤同样具有一定的参考意义。     

100毫米狄舍尔轧管机问题的分析

在指出鞍钢无缝钢管厂φ100毫米狄舍尔轧管机存在问题的基础上,提出了改进意见,并重点分析了导盘位置、导盘速度与轧管过程之间的关系。     

ZG56CrNiMoV7热作模具铸钢导盘质量控制与热处理

采用中频炉冶炼生产热作模具钢导盘,给出了铸造质量控制与成分控制原则。根据探伤情况,在调质热处理工艺的淬火冷却环节上采用不同介质实现ZG56CrNiMoV7热作模具铸钢导盘的淬火冷却。制定了相应的热处理工艺参数,自己设计专用淬火吊具淬火,成功进行了ZG56CrNiMoV热作模具铸钢导盘的淬火。导盘性能完全满足使用要求,为中频炉冶炼生产大型热作模具铸钢件并采用相应热处理控制技术,提供了重要参数。     

新型狄舍尔穿孔机主要参数分析

导盘设在入口位置比较合理,建议按 x=N+Z(0.5～1.0)确定其位置。导盘最大直径与轧辊直径之比应为1.52～2.05。导盘圆周速度与轧辊轴向速度之比应为1.5～3.0。     

单主动导盘二辊斜轧穿孔机中金属变形

本文提出了单主动导盘二辊斜轧穿孔机,这种穿孔机有许多优点,主要是轧机结构简化、调整灵活、穿孔速度效率高、轧制过程稳定、不易形成孔腔以及可实现大倾角下轧制等.本文仅对单主动导盘穿孔机轧制变形规律做一理论分析.     

ACCU—Roll轧管机导盘偏心距的确定

本文通过ACCU－Roll轧管机轧辊和导盘空间位置关系和速度匹配关系的分析，并经现场实践的检验，确定了切合生产实际的导盘偏心距。     

宝钢钢管厂穿孔机调整参数简析

宝钢钢管厂穿孔机由西德曼内斯曼钢管公司引进,系导盘式二辊斜轧机。该轧机与国内常见的二辊斜轧穿孔机有所不同的是:①两个主动旋转的大直径导盘代替了固定导板;②轧辊入口段设计成两段锥。这两点区别将对顶头前压缩量和空心坯扩径产生影     

新型穿孔机

本设备是使用锥形辊和大导盘的新型穿孔机,并采用了陈惠波专家的辊形曲线专利,用于此穿孔机上,这种穿孔机具有独特的优点,使穿出的毛管质量达到了高的标准,为穿孔连铸坯和薄壁毛管提供了有利条件。设备设计新颖,结构紧凑,重量轻,为国内小型穿孔机组改造提供了理想产品。     

Prevalence of morphological changes in the surfaces of the temporomandibular joint disc associated with internal derangement

PURPOSE: The purpose of this study was to determine the prevalence of morphological changes in the superior and inferior surfaces in the temporomandibular joint (TMJ) disc and relate them to disc displacement. MATERIALS AND METHODS: Thirty TMJs obtained from fresh cadavers were studied. The TMJs were dissected, and the superior and inferior surfaces of the disc were inspected and classified as intact, irregular, or perforated. These findings were corrolated to the position of the disc. RESULTS: There was a greater prevalence of morphologic changes in the inferior (57%) than in the superior surface (17%) of the disc (P < .001). This was found for joints both with normal disc position and those with disc displacement. There was no relationship between surface irregularities of the inferior surface and the position of the disc. Perforation was seen more frequently in joints with disc displacement than in those with normal disc position. CONCLUSION: Morphologic changes in the inferior surface of the TMJ disc are more prevalent than those in the superior surface, but this is not related to disc position. However, this needs to be considered when doing arthroscopy of only the superior joint compartment.     

Biochemistry of the intervertebral disc

In comparison to other tissues, understanding the disc biochemistry is only in the very early stage. The few facts that are known would point to strategies for interventions to alter disc biology and maintain disc biomechanics.     

Centrifugal atomisation of metallic alloys in inductive plasma onto cooled disc

Abstract

A novel atomisation process for the production of high purity, fine powders of high melting point metallic alloys has been devised. This process associates centrifugal atomisation and inductive plasma techniques. The experimental equipment is described. Results obtained by atomising nickel base superalloy PER3, Ti–0·17%Pd alloy, and pure copper on a cooled copper alloy disc are presented. The effects of process parameters, such as the disc rotation speed and the aerodynamic environment of the disc, on the atomised product characteristics, are investigated. The alloys were melted drop by drop onto a water cooled disc. The atomisation of the dripped alloy can be characterised by three mechanisms: ultraquenched flakes and crusts solidified on the disc; spherical droplets formed by centrifugation; spherical droplets formed by aerodynamic erosion.     

Paraoxonase (PON1) gene in mice: sequencing, chromosomal localization and developmental expression

PURPOSE: To retrospectively examine the optic disc photographs of a glaucoma population for optic disc haemorrhages, vascular occlusions and vascular abnormalities. METHODS: The optic disc photographs of 906 eyes of glaucoma and suspect glaucoma patients were examined. Optic disc photographs were taken annually, where possible, with the follow-up period varying between 1 and 14 years duration (mean, 2.89). Glaucoma patients are regularly reviewed every 4-6 months and glaucoma suspects every 1-2 years, depending on the ophthalmologist. Low-tension glaucoma patients were reviewed more frequently (mean, every 2.6 months). The results of the findings were compared to a control group of 39 subjects with a mean follow-up period of 7 years, using Fisher's exact test. RESULTS: It was found that during the period under review, 7.4% (n = 67) of eyes had optic disc haemorrhages. The highest frequency of optic disc haemorrhages (37.5%) was found in the low tension glaucoma group (P = 0.0001) followed by 11% of primary open-angle glaucoma eyes (P = 0.03). In the normal group there were three eyes with optic disc haemorrhages and one with a disc collateral, which constitutes 5.1% vascular changes in this sub-group. Of the study eyes 2.8% had central retinal vein occlusions, 1.3% branch vein occlusion, 1.2% disc vessel abnormalities (loops) and 1.1% disc collaterals. Discrete nerve fibre layer haemorrhages and microaneurysms were found in 0.8% and 1.8% of eyes, respectively. CONCLUSIONS: A total of 16.8% of the eyes observed in this study had either disc haemorrhages or vascular changes. The underlying trend of vascular and haemorrhagic changes in glaucoma are demonstrated in this sample, which is in general agreement with previous studies. The high percentage of optic disc haemorrhages in low tension glaucoma is highlighted. The presence of microaneurysms and nerve fibre layer haemorrhages is interesting but of unknown significance.     

Antitumour and immunosuppressive activity of hydroxyanthraquinones and their glucosides

The variation with age and spinal level of the glycosaminoglycan distribution in the greyhound (a non-chondrodystrophoid breed) intervertebral disc has been assessed by means of histochemical and chemical methods. The principal glycosaminoglycans of the greyhound disc are the chondroitin sulphates. With ageing, there is evidence of a decline in these components and the replacement by keratosulphate. The discs of this breed contain high proportions of sialic acid and hexosamines well into old age which are thought to be associated with non-collagenous proteins (glycoproteins). The maintenance of glycosaminoglycans and glycoprotein levels in the disc nucleus pulposus into old age is possibly associated with the relatively low incidence of disc disorders in the non-chondrodystrophoid breeds.     

Morphologic changes in the elastic fibers of the temporomandibular joint after experimental disc perforation in the rabbit

PURPOSE: Elastic fibers in the attachment regions of the temporomandibular joint (TMJ) are considered important in the movements of the disc during jaw motion. This study was designed to determine whether there are change in the elastic fibers of the TMJ when the disc is perforated for a long period. MATERIALS AND METHODS: Each TMJ of five rabbits was surgically exposed, and a mediolateral perforation was made in the center of the articulating region of the disc with a scalpel. Five untreated and three sham-operated rabbits were used as controls. The TMJs were removed after 10 months and processed for histochemical demonstration of elastic fibers. RESULTS: Osteoarthritic changes and a significant decrease in number of the elastic fibers in the anterior-inferior attachment and posterior-inferior attachment of the TMJ disc were observed after disc perforation. Conversely, elastic fibers appeared in the fibrous tissue on the resorbed bone of the articular eminence. CONCLUSIONS: Experimental disc perforation changes the distribution and density of the elastic fiber in the TMJ as well as causes osteoarthritis. A knowledge of these facts may improve our understanding of perforation of the disc.     

Creep behavior of a rotating functionally graded composite disc operating under thermal gradient

Creep behavior of a rotating disc made of isotropic functionally graded material (FGM) has been investigated. The disc under investigation is made of a composite containing silicon carbide particles in a matrix of pure aluminum. The creep behavior has been described by Sherby’s law. The disc is considered as having a thermal gradient in the radial direction. The present analysis indicates that for the assumed linear particle distribution, the steady-state strain rates are significantly lower compared to that in an isotropic disc with uniform particle distribution. It is also found that the strain rates in composite discs operating under thermal gradient are reduced as compared to similar discs under a uniform average temperature.     

Matrix metalloproteinases in the human intervertebral disc: role in disc degeneration and scoliosis

STUDY DESIGN: Biochemical study of human intervertebral discs collected at surgery from patients with low back pain associated with disc degeneration or scoliosis. Matrix metalloproteinases were studied by quantitative zymography. OBJECTIVE: To determine whether changes in the expression of matrix metalloproteinases will bring about tissue remodelling that contributes to the progressive nature and pathology of these diseases of the intervertebral disc. SUMMARY OF BACKGROUND DATA: The diseases of the intervertebral disc, degenerative disc disease and scoliosis, are both characterized by changes in the extracellular matrix components that will affect the mechanical function of the tissue. Matrix metalloproteinases are known to have the capability of degrading all the known extracellular matrix components of the disc. METHODS: Matrix metalloproteinases 2 and 9 were detected by gelatin-gel zymography and quantified by laser scanning densitometry. Both pro and active forms of the enzymes were measured. Thirty-four discs from patients with low back pain and 29 from patients with scoliosis were investigated. RESULTS: A correlation was found between the increasing levels of matrix metalloproteinases 2 and 9 and the grade of degenerative disc disease. In addition, the levels of these enzymes show a differential expression across the scoliotic disc with the highest levels in samples taken from the convexity of the curve. CONCLUSIONS: The difference between the concave and convex side of the scoliotic curve indicates that mechanical loads might influence the expression of these enzymes. The increased expression of these enzymes in both degenerative disc disease and scoliosis strongly suggests that they may affect the progressive nature of these diseases.     

Gadolinium-enhancement characteristics of magnetic resonance imaging in distinguishing herniated intervertebral disc versus scar in dogs

STUDY DESIGN: This study is an experimental investigation on the gadolinium contrast magnetic resonance imaging (MRI) in distinguishing sequestered disc fragment versus scar in dogs. The conspicousness of the disc fragment and signal intensities of the disc fragment and laminectomy scar were evaluated using gadolinium-enhanced MRI and histology. OBJECTIVES: This study investigated the effects of timing of gadolinium injections, gadolinium doses, and aging of scar or disc on the enhancement characteristics and conspicuousness of disc fragment in MRI. SUMMARY OF BACKGROUND DATA: Contrast-enhanced MRI has been frequently used as a procedure to evaluate patients with suspected recurrent herniated discs. In contrast-enhanced MRI, the postoperative scar tissue enhances to a greater extent than disc fragments. Previous reports suggest different contrast enhancement characteristics of scar depending on doses, timing of gadolinium, or maturity of scar. There are different compounds of gadolinium agents and different doses are becoming available. There is no previous report on the evaluation of gadolinium enhancement characteristics in dogs with concurrent herniated disc and scar. METHODS: Six conditioned Beagle dogs underwent hemilaminectomies and discectomies at the L3-L4 level. An autogenous disc fragment was obtained from the intervertebral disc of the tail. This disc fragment was placed anterolateral to the thecal sac, simulating a sequestered disc herniation. Three control animals underwent hemilaminectomies and discectomies alone. Each dog underwent MRI on a 1.5 Tesla scanner (3.0 mm slice in sagittal and axial projections with TR 500, TE 30 msec and high dose 0.3 mmol/kg of gadoteridol). Images were obtained at 15 days, 30 days, 60 days, and 90 days after surgery. At each imaging session, contrast enhancement was measured at 2 minutes, 25 minutes, and 45 minutes after gadolinium injection for kinematic analysis. Two animals at a time were killed on 30 days, 60 days, and 90 days postoperatively. Magnetic resonance imaging was done with conventional low dose 0.1 mmol/kg of gadopentetate at 15 days and before death. RESULTS: Results revealed that the difference of enhancement between disc and the scar and therefore conspicuousness of disc fragment was greater on 2-23-minute images as compared with 45- minute images, and the distinction decreased with aging of the scar. The high dose contrast-enhanced MRI increased signal intensities for both disc and scar. Conspicuousness of disc fragment seemed to be better with the high-dose gadolinium compound. CONCLUSIONS: In conclusion, contrast enhancement characteristics in MRI may depend on the timing of MRI after gadolinium injection, doses of gadolinium, and aging of scar or disc.     

新型盘式过滤机的研究与应用

本文概述了新型盘式过滤机的国外发展情况，介绍了其工作原理，并提出了国内研究盘式过滤机的发展方向。