Assessment of several typical physical properties of reclaimed farmland filled with Yellow River sediment in Jining, China

Land subsidence caused by underground coal mining is one of the most prominent environment problems in China. The reclamation of mining subsidence land with Yellow River sediment was considered to be feasible, but its effectiveness needs to be verified. An integrated reclamation technology with Yellow River sediment was evaluated using a comparison of actual crop production soil profile analysis in Jining City, China. The results indicated that reconstructed soil profile of the reclaimed farmland was less effective in retaining water and in supporting plant growth than that of the unaltered farmland. Some measures are proposed, such as reducing the drainage velocity to allow sedimentation and retention of the clay and silt, changing the techniques of filling the Yellow River sediment and increasing the organic matter content in the soil layers to improve the capacity to retain water in the reclaimed farmland.

Calcitonin gene-related peptide in anterior and posterior horns of spinal cord after brachial plexus injury

BACKGROUND： The changes of calcitonin gene-related peptide （CGRP） expression are closely associated with peripheral nerve injury, whereas it should be further investigated whether the damage of central nerve can lead to the changes of CGRP expression, and whether it is associated with the neural regeneration and repair. OBJECTIVE： To observe the changing law of CGRP expression in the anterior and posterior horns of spinal cord following brachial plexus injury. DESIGN： A randomized controlled trial. SETTINGS： Department of Anatomy, Yunyang Medical College; Department of Anatomy, Basic Medical College, Sun Yat-sen University. MATERIALS： Sixty-five adult male SD rats of clean degree, weighing 180 - 220 g, provided by the experimental animal center of the Basic Medical College, Sun Yat-sen University, were randomly divided into control group （n =5） and experimental group （n =60）, and the latter was subdivided into three damage groups： avulsion of anterior root group （n =20）, disjunction of posterior root group （n =20） and transection of spinal cord group （n =20）. Diaminobenzidine （DAB） chromogen, rabbit anti-CGRP polyclonal antibody were the products of Sigma Company; Leica image analytical apparatus was produced by QUIN Company （Germany）; Histotome by Sigma Company. METHODS： The experiments were carried out in the Department of Anatomy, Basic Medical College, Sun Yat-sen University from September 2004 to March 2005. Three kinds of models of brachial plexus injury were established： In the avulsion of anterior root group, right C7 anterior root was avulsed, and the distal nerve residual root was transected. In the disjunction of posterior root group, right C7 anterior root was avulsed and right C5 - T1 posterior horns were cut to block the sensory afferent pathway. In the transection of spinal cord group, right C7 anterior root was avulsed and C5-6 segments of right spinal cord were semi-transected to block the cortical descending pathway. In the control group, C5 - T1 vertebral plates were prayed open, and then the skin was sutured. The C7 segments of spinal cord were removed on the 1^st, 3^rd, 7^th and 14^th days postoperatively respectively, and the CGRP expressions in the anterior and posterior horns of spinal cord were determined and analyzed using immunohistochemical method and image analysis. MAIN OUTCOME MEASURES： ① Number of CGRP immuno-positive motor neurons in the anterior horn of spinal cord; ② Total area ofCGRP immuno-positive fibers in the posterior horn of spinal cord. RESULTS： All the 65 rats were involved in the analysis of results. ① Number of CGRP immuno-positive motor neurons in the anterior horn of spinal cord： CGRP immuno-positive motor neurons could be observed in the anterior horns of C7 spinal cord in the control group and damage groups, the neurons had big cell body with stained cytoplasm, appeared as brown granules, and mainly distributed in the ventral lateral anterior horn of spinal cord. On the Ist day postoperatively, the number of CGRP positive neurons was obviously higher in the in the avulsion of anterior root group than in the control group （P 〈 0.01）, whereas obviously lower in the disjunction of posterior root group than in the control group （P 〈 0.01）, and there was no obvious difference between the transection of spinal cord group and the control group （P 〉 0.05）. On the 7^th day, the numbers of CGRP positive neurons in the damage groups were obviously higher than that in the control group （P 〈 0.01）, also obviously different from those on the 1^st day in the same group respectively （P 〈 0.01）. On the 14^th day, the number of CGRP positive neurons in the disjunction of posterior root group was decreased, but there was no obvious difference as compared with that in the control group, whereas those in the avulsion of anterior root group and transection of spinal cord group were still obviously higher than that in the control group （P 〈 0.01）. The number of CGRP positive neurons was the most in the avulsion of anterior root group, followed by the transection of spinal cord group, and the least in the disjunction of posterior root group, and there were significant differences among them （P 〈 0.01）. ② Total area of CGRP immuno-positive fibers in the posterior horn of spinal cord： Dense CGRP immuno-positive nerve fibers distributed in the layers Ⅰ and Ⅱ of the C7 posterior horn of spinal cord in the control group. On the 1^st day postoperatively, the total areas of CGRP positive fibers in the avulsion of anterior root group and transection of spinal cord group were obviously larger than that in the control group （P 〈 0.01）, whereas there was no obvious difference between the disjunction of posterior root group and control group. On the 7^th day, the CGRP expression in the posterior horn of spinal cord decreased to the lowest level in the disjunction of posterior root group, whereas there were no obvious differences in the avulsion of anterior root group and transection of spinal cord group as compared with that in the control group （P 〉 0.05）. On the 14^th day, the area continued to decrease in the avulsion of anterior root group and transection of spinal cord group, and it was obviously lower in the transection of spinal cord group than in the control group （P 〈 0.01）, and it was slightly increased in the disjunction of posterior root group as compared with that on 7^th day, but still obviously lower than that in the control group （P 〈 0.01）. CONCLUSION： The expression and role of CGRP are in discrepancy in the anterior and posterior horns of spinal cord after brachial plexus injury. The CGRP in anterior horn of spinal cord are derived from the cell body of motor neurons, and may be involved in the repairing mechanism of nerve injury regeneration; Whereas those in the posterior horn are mainly derived from posterior root ganglion, and may be associated with the conduction of noxious stimulations.

ROC analysis of CT hemodynamic in the diagnosis of breast cancer

Objective:The aim of this study was evaluate the diagnostic value of computed tomography(CT) perfusion in breast cancer by the method of receiver operator characteristic curve(ROC) analysis.Methods:Eighty-one cases with breast masses found by health examination or mammography were scanned by multi-slice spiral CT(MSCT) perfusion and hemodynamic parameters of blood flow(BF), mean transit time(MTT) and blood volume(BV) were calculated by deconvolution arithmetic.According to the pathologic results, two groups, benign and malignant were classified and statistical analysis were performed between them.The ROC characteristics of BF, MTT, BV were compared for each and the diagnostic value of the hemodynamic parameters were confirmed.Results:In the malignant group, BF was(0.735 ± 0.440) mL/min/mL, MTT was(22.771 ± 7.647) s and BV was 0.234 ± 0.082.In the benign group, BF was(0.466 ± 0.527) mL/min/mL, MTT was(26.712 ± 12.934) s and BV was 0.179 ± 0.117.There was a significant difference for BF and BV between the benign and malignant groups.When the hemodynamic parameters were used to discriminate the breast lesions, the area under the ROC curve(AUCROC) of BF was 0.832 ± 0.086, the maximum, while AUCROC of BV was 0.695 ± 0.092.There was no significant statistical difference between BF and BV.AUCROC of MTT was 0.473 ± 0.102, which was minimal.Since the threshold of BF was 0.381 mL/min/mL, the sensitivity was 82.3%, the specificity was 73.2%, the positive likelihood ratio(LR) was 3.071 and the negative LR was 0.242.The threshold of BV was 0.190 with sensitivity 73.3%, specificity 56.5%, positive likelihood ratio 1.685 and negative LR 0.473.Conclusion:BF and BV among CT hemodynamic parameters have certain diagnostic value in breast cancer, but BF or BV can not yet be single index to confirm or deny the diagnosis.

国产低Mo耐火钢高大空间建筑雨棚结构抗火设计

火灾是钢结构安全的主要威胁之一,传统钢结构的主要防火措施为涂抹防火涂料、浇筑混凝土形成组合结构或设置防火板,其中又以防火涂料应用最为广泛。然而,室外涂抹防火涂料耐久性差,存在坠落伤人隐患。且对于防火要求较高的钢结构需厚涂防火涂料,这尤其会影响地标性建筑的建筑效果。近年来,耐火钢作为一种新型的防火保护措施逐渐兴起,其能够有效避免上述防火措施的缺点,但由于大量添加合金元素Mo导致其成本往往较高。南钢集团研发的新型低Mo耐火钢在保证优异抗火性能的同时减少了Mo元素的添加量,从而减小了综合制造成本而受到广泛关注。基于构件承载力法,依托于某具有高大空间的钢结构大雨棚,对南钢新型低Mo耐火钢在抗火设计中的应用可行性进行了研究。作为某市新建地标性建筑,设计要求大雨棚屋面梁应满足3 h耐火极限。首先探索了高温下该国产耐火钢的材性折减规律,通过与现行规范理论计算结果对比,发现该国产耐火钢满足通用耐火钢的材性折减要求且可根据规范相应公式准确预测不同温度下的材性折减。随后基于结构抗火设计原则共确定了11个火灾场景,分别分布于雨棚边跨及中跨。以上火灾场景被认为已覆盖该大雨棚实际使用状态下可能发生的所有火灾。进一步根据相关规范,分析了各火灾场景下大雨棚的升温规律。分析表明,按照设计要求经3 h升温后,边跨火灾场景下最高空气温度接近750℃,最高构件温度接近730℃;中跨火灾场景下最高空气温度接近600℃,最高构件温度接近570℃,均远低于ISO 834标准火灾升温。高大空间建筑火灾下升温低的特点表明高大空间建筑可作为未来耐火钢应用的主要场景。最终,分别采用Q355普通结构钢与Q345FR国产耐火钢对各火灾工况下各构件进行承载力和稳定性验算。结果表明,若仅采用Q355普通结构钢,高温下钢梁GL3、GL3a及GL4无法满足承载力要求;而若采用Q345FR耐火钢,屋顶钢构件的强度和整体稳定性均能满足要求。

T形件-钢管螺纹锚固单边螺栓连接受拉性能试验研究

钢结构框架柱采用闭口截面具有截面承载效率高、抗扭模量大等优势。利用螺纹锚固单边螺栓可以解决钢梁-钢管柱无法采用普通高强螺栓直接连接的问题。螺纹锚固单边螺栓是通过在柱壁上加工带有螺纹的螺栓孔,直接将高强螺栓拧紧在柱壁的螺纹孔上来代替传统螺母,实现在钢管柱外侧安装和拧紧。在螺纹锚固单边螺栓双T形节点模型研究的基础上,进一步研究了螺纹锚固单边螺栓连接T形件-钢管的受力机理和破坏模式。对10个采用螺纹锚固单边螺栓连接T形件-钢管节点进行了受拉试验研究,分析和对比了不同节点破坏模式、承载力机理、位移-荷载曲线、屈服承载力和极限承载力等。试验发现:节点共发生了四种破坏,分别为螺纹剪切破坏、管壁局部屈服伴随螺纹剪切破坏、螺栓杆拉断破坏和管壁屈服破坏。当钢管壁厚度较小时,节点发生螺栓孔内螺纹剪切破坏,当管壁较厚,螺栓直径相对较小时,发生螺栓杆拉断破坏,但螺纹孔内螺纹保持完好,表明当螺栓孔内螺纹长度足够时,钢管壁螺栓孔内螺纹具有足够的承载力,螺纹锚固方式可行。同时对比分析了螺栓间距、螺栓直径及管壁厚度对节点承载力的影响。试验结果表明:增大螺栓直径、管壁厚度、螺栓间距等,均可以提高节点的承载力;螺栓间距对节点承载力的影响与钢管壁在螺栓拉力作用下屈服线的形状有关,当螺栓间距较小时,各受拉螺栓对钢管壁的屈服线相互叠加,随着螺栓间距增大,节点承载力明显提高;但当螺栓间距较大,各受拉螺栓对钢管壁屈服线为长圆形,随螺栓间距的增加,节点承载力将保持不变;随着螺栓直径的增加,节点的破坏模式逐渐从螺杆拉断破坏改变为钢管壁螺栓孔螺纹破坏或钢管壁屈服破坏,节点承载能力增加;管壁厚度增加显著提高钢管壁屈服承载力,其增长率与壁厚的增长率近似呈平方的关系。为了避免钢管壁较薄时,管壁螺栓孔内螺纹锚固力不足的问题,进一步研究了钢管内设垫板对螺纹锚固单边螺栓T形件-钢管连接节点受力性能的影响。试验结果表明:垫板增加了螺纹锚固长度,加强后的节点承载力显著提高,有效地避免螺纹剪切破坏,但初始刚度变化不大。