S-LET复合型柔性铰链设计与性能研究

综合LET型铰链与S型铰链结构性能特点,提出了一种S-LET复合型柔性铰链,设计了该铰链的外形结构,并对其等效刚度进行分析,推导出铰链弯曲时的等效刚度计算公式。通过对不同尺寸S-LET复合型铰链弯曲等效刚度的分析,得出弯曲等效刚度修正系数,并验证了该系数的有效性。最后,通过对S型、LET型及S-LET复合型铰链弯曲变形及扭转变形的有限元仿真结果的比较,得出S-LET弯曲变形能力在S型与LET型铰链之间,而扭转变形则是三者中最小。

Molecular mechanism of action of anti-tumor necrosis factor antibodies in inflammatory bowel diseases

Anti-tumor necrosis factor(TNF) antibodies are successfully used in the therapy of inflammatory bowel diseases(IBD). However, the molecular mechanism of action of these agents is still a matter of debate. Apart from neutralization of TNF, influence on the intestinal barrier function, induction of apoptosis in mucosal immune cells, formation of regulatory macrophages as well as other immune modulating properties have been discussed as central features. Nevertheless, clinically effective anti-TNF antibodies were shown to differ in their mode-of-action in vivo and in vitro. Furthermore, the anti-TNF agent etanercept is effective in the treatment of rheumatoid arthritis but failed to induce clinical response in Crohn's disease patients, suggesting different contributions of TNF in the pathogenesis of these inflammatory diseases. In the following, we will review different aspects regarding the mechanism of action of anti-TNF agents in general and analyze comparatively different effects of each antiTNF agent such as TNF neutralization, modulation of the immune system, reverse signaling and induction of apoptosis. We discuss the relevance of the membranebound form of TNF compared to the soluble form for the immunopathogenesis of IBD. Furthermore, we review reports that could lead to personalized medicine approaches regarding treatment with antiTNF antibodies in chronic intestinal inflammation, by predicting response to therapy.

Eosinophils in the gastrointestinal tract and their role in the pathogenesis of major colorectal disorders

Eosinophils are currently regarded as versatile mobile cells controlling and regulating multiple biological pathways and responses in health and disease.These cells store in their specific granules numerous biologically active substances(cytotoxic cationic proteins, cytokines, growth factors, chemokines,enzymes) ready for rapid release. The human gut is the main destination of eosinophils that are produced and matured in the bone marrow and then transferred to target tissues through the circulation. In health the most important functions of gut-residing eosinophils comprise their participation in the maintenance of the protective mucosal barrier and interactions with other immune cells in providing immunity to microbiota of the gut lumen. Eosinophils are closely involved in the development of inflammatory bowel disease(IBD),when their cytotoxic granule proteins cause damage to host tissues. However,their roles in Crohn’s disease and ulcerative colitis appear to follow different immune response patterns. Eosinophils in IBD are especially important in altering the structure and protective functions of the mucosal barrier and modulating massive neutrophil influx to the lamina propria followed by transepithelial migration to colorectal mucus. IBD-associated inflammatory process involving eosinophils then appears to expand to the mucus overlaying the internal gut surface. The author hypothesises that immune responses within colorectal mucus as well as ETosis exerted by both neutrophils and eosinophils on the both sides of the colonic epithelial barrier act as additional pathogenetic factors in IBD. Literature analysis also shows an association between elevated eosinophil levels and better colorectal cancer(CRC) prognosis, but mechanisms behind this effect remain to be elucidated. In conclusion, the author emphasises the importance of investigating colorectal mucus in IBD and CRC patients as a previously unexplored milieu of disease-related inflammatory responses.

Erdheim chester-A rare disease with unique endoscopic features

Erdheim-Chester disease(ECD) is a rare inflammatory syndrome in which systemic infiltration of non-Langerhans cell histiocytes occurs in different sites. Both the etiology and pathophysiology of ECD are unknown, but CD68 positive CD 1a/S100 negative cells are characteristic. The presentation of ECD differs according to the involved organs. This case report describes a patient with ECD and the gastrointestinal manifestations and unique endoscopic appearance as seen in gastroscopy and colonoscopy with histological proof of histiocyte infiltration of the lamina propria. The clinical and endoscopic findings of this unique case, to our knowledge, were never described before, so were the features of the gastrointestinal involvement in this disease.

Flaporhexis: Alternative Way to Make a Femtosecond Laser Corneal Flap

Flaporhexis, a technique to make the femtosecond laser corneal flap was developed primarily to reduce the mechanical trauma associated with separating the corneal tissue by taking advantage of the cornea’s natural anatomy and was first described in a peer reviewed artice in 2008. The anterior part of the cornea tends to be stronger, thereby allowing tearing (Greek “rhexis”) along the preformed cuts of the femtosecond photo disruption. Flaporhexis differs from Binder’s technique of “hinge opening” as published in 2006 by opening the flap from the opposite side. If a femtosecond flap lift is performed correctly, the surgeon will find a virgin, uniform, dry stromal bed, which had not been manipulated by any surgical instrument and is therefore perfect for wavefront guided laser surgery as “Sub-Bowman’s Keratomileusis”.

哈氏棒内固定术中应用椎板截骨分析

目的 :在哈氏棒手术中应用椎板三角形截骨方法 ,提高哈氏棒内固定系统的稳定性 ,减小手术难度和使内固定系统的安置更易进行 ,使棒钩的弯曲面与椎板的接触面贴合合理、紧密。方法 :总结哈氏棒手术的经验 ,设计椎板三角形截骨。结果 :本组 80例采用椎板三角形截骨 ,减少了手术难度 ,缩短了手术时间 ,提高了内固定系统的效用 ,有避免术后断棒、脱钩和减小脊柱旋转的作用。结论

零磁场中L-G方程中的系数α,β

本文讨论和推导了L-G方程系数α,β的三种表达式,并指出了其错误,给出了相应的S-N,S-S结的转变温度表达式.

平纹编织复合材料吸湿行为试验及有限元模拟

试验测定了一种平纹编织复合材料的吸湿曲线,并建立了包含平纹编织细观结构的层合板吸湿有限元模型。通过该模型研究了层合板的铺层位置的随机偏移、铺层角度比例及纤维束中纤维体积含量对吸湿的影响。研究表明:平纹编织复合材料层合板吸湿行为基本符合Fick定律;细观有限元模型分析的结果和试验吻合良好;铺层位置的随机偏移对平衡吸湿时间有影响;复合材料铺层角度比例不同对平纹编织复合材料的平衡吸湿量略有影响,对平衡吸湿时间没有明显影响;平纹编织复合材料的纤维束中纤维含量升高,更易达到吸湿平衡,但平衡吸湿率和吸湿速率降低。

Advances in myopia research anatomical findings in highly myopic eyes

Background:The goal of this review is to summarize structural and anatomical changes associated with high myopia.Main text:Axial elongation in myopic eyes is associated with retinal thinning and a reduced density of retinal pigment epithelium(RPE)cells in the equatorial region.Thickness of the retina and choriocapillaris and RPE cell density in the macula are independent of axial length.Choroidal and scleral thickness decrease with longer axial length in the posterior hemisphere of the eye,most marked at the posterior pole.In any eye region,thickness of Bruch’s membrane(BM)is independent of axial length.BM opening,as the inner layer of the optic nerve head layers,is shifted in temporal direction in moderately elongated eyes(axial length<26.5 mm).It leads to an overhanging of BM into the intrapapillary compartment at the nasal optic disc side,and to an absence of BM at the temporal disc border.The lack of BM at the temporal disc side is the histological equivalent of parapapillary gamma zone.Gamma zone is defined as the parapapillary region without BM.In highly myopic eyes(axial length>26.5 mm),BM opening enlarges with longer axial length.It leads to a circular gamma zone.In a parallel manner,the peripapillary scleral flange and the lamina cribrosa get longer and thinner with longer axial length in highly myopic eyes.The elongated peripapillary scleral flange forms the equivalent of parapapillary delta zone,and the elongated lamina cribrosa is the equivalent of the myopic secondary macrodisc.The prevalence of BM defects in the macular region increases with longer axial length in highly myopic eyes.Scleral staphylomas are characterized by marked scleral thinning and spatially correlated BM defects,while thickness and density of the choriocapillaris,RPE and BM do not differ markedly between staphylomatous versus non-staphylomatous eyes in the respective regions.Conclusions:High axial myopia is associated with a thinning of the sclera and choroid posteriorly and thinning of the retina and RPE density in the equatorial region,while BM thickness is independent of axial length.The histological changes may point towards BM having a role in the process of axial elongation.

纹层方向对泥页岩纵、横波速度及弹性参数影响的试验研究

纵、横波速度是研究页岩各向异性的重要参数。为了研究纹层方向对纵、横波速度及动态弹性参数的影响,以我国东部中新生代的湖相泥页岩为研究对象,对不同纹层方向的取芯样品进行纵、横波速度实验。结果表明:纵横波波速比与纹层方向不具有相关性,与微裂缝的主要延伸方向有关;纵、横波传播方向与纹层的夹角越小,纵横波速度越大;不同纹层方向下的纵波速度和横波速度始终保持线性相关,其线性曲线的斜率、截距分别与纹层界面、微裂缝相关;动态弹性模量和纹层方向有良好的相关性,其主要受纹层界面影响,而动态泊松比与纹层方向无关,其主要受微裂缝影响。