A New Index of Energy Dissipation Considering Time Factor under the Impact Loads

Rock failure phenomena are accompanied by abundant energy variation, and the energy dissipation can explain the dynamic mechanical characteristics of the rock. In this study, a series of granite specimens (a total of 60) with different aspect ratios were dynamically loaded by a split Hopkinson pressure bar (SHPB) to explain the energy dissipation and the rock-crushing degree under dynamic load. A new index, namely energy time density (w_td), is proposed to evaluate the energy dissipation considering the time factor. The relationships between strain rate, energy time density, and specific energy absorption are analyzed. A metric (K_u) is defined to describe the degree of rock fragmentation quantitatively. The correlations of fractal dimension and K_u with different impact pressures are compared. It was concluded that there is a noticeable peak point in the energy time density curve. The energy time density of the stress equilibrium point is three times that of the peak point. The energy time density declines after the peak point, then the energy consumption density tends to be stable. The linear relationship between strain rate and peak point energy time density is stronger. The new index can describe energy dissipation well under dynamic loading. In addition, the experimental results indicate that the degree of crush K_u can describe the degree of crush, and the effect of fractal dimension to quantify the fracture characteristics of the rocks is less good in this test. The crushing degree of rocks increases with the increase of strain rate. Furthermore, the prediction effect of energy time density is better than that of strain rate about K_u.     

Clinical features of intracerebral hemorrhage in patients with colorectal cancer and its underlying pathogenesis

BACKGROUNDThe diagnosis of both cancer and intracerebral hemorrhage (ICH) in the same patient is not uncommon, but the clinical features and pathogenesis of patients with colorectal cancer (CRC) and ICH are still not well known.AIMTo investigate the clinical features and underlying pathogenesis of ICH in patients with CRC. METHODSA retrospective review of CRC patients complicated with ICH from three centers between January 2014 and December 2020 was performed. Clinical data such as laboratory examinations, imaging features, prognosis, and underlying pathogenesis were analyzed.RESULTSOf 16673 identified CRC patients, 20 (0.12%) suffered from ICH. There were 13 males and 7 females, with an average age (mean ± SD) of 68.45 ± 10.66 years. Fourteen patients (70%) had distant metastases and most patients (85%) showed an elevation of one or more cancer biomarkers. The hemorrhagic lesions in 13 patients (65%) were in the intracerebral lobe. Four patients were completely dependent and 4 died within 30 days after hemorrhage. Intratumoral hemorrhage (50%) and coagulopathy (50%) accounted for the majority of hemorrhages.CONCLUSIONPatients with ICH and CRC often have clinical features with lobar hemorrhage, distant metastases and poor prognosis. Intratumoral hemorrhage and coagulopathy are the main causes of ICH in patients with CRC.     

125I-碘酞酸盐临床应用进展

125I-碘酞酸盐在美国应用至今已超过半个多世纪。其主要应用于评价肾小球滤过率(GFR), 特别是在肝肾移植患者中肾功能的评价上具有非常重要的作用, 具有方法简单、准确的特点。目前国内大多采用内生肌酐清除率、99Tcm-DTPA肾动态显像或者99Tcm-DTPA双血浆法来测定GFR。但这些方法评估GFR的价值有限。笔者将系统阐述125I-碘酞酸盐的原理、方法、临床应用、辐射安全等, 以期为国内临床应用奠定基础。     

Notch信号通路在小儿哮喘患者外周血单个核细胞的表达及其临床意义

目的初步探讨Notch信号通路相关分子在小儿哮喘患者中的表达及其临床意义。方法实时荧光定量聚合酶链反应和流式细胞术,分别从基因转录和蛋白表达水平检测20例小儿哮喘患者和20例健康对照者的外周血单个核细胞(PBMC)中Notch1、Notch2、Notch3、Notch4以及Notch的配体Jagged1、Jagged2、DLL1(Delta-like1)、DLL3(Delta-like3)、DLL4(Delta-like4)的表达。结果小儿哮喘患者PBMC中的Notch1、Notch3、Jagged1、Jagged2、Delta1的mRNA和蛋白的表达均明显高于健康对照组(P<0.01),Notch2、Notch4、Delta3和Delta4的基因和蛋白的表达在两者中未见明显差异(P>0.05)。结论 Notch信号通路的表达在小儿哮喘发病过程中有显著改变,可能参与小儿哮喘的发生发展,为深入研究小儿哮喘的发病机制提供思路。     

增强后薄层动态CT对孤立性肺结节病变的评价(附45例病例分析)

目的：定量评价孤立性肺结节病变在增强后薄层动态ＣＴ扫描中的特征表现,探讨其敏感度及特异度。方法：选取直径小于３ｃｍ的孤立性肺结节病变４５例在薄层ＣＴ平扫及增强后２５ｓ,２ｍｉｎ及５ｍｉｎ对病灶感兴趣区进行ＣＴ值的测定,进行统计学分析。结果：４５例病灶在强化上呈三种形式：增强后明显强化（增强前后差值≥４０ＨＵ）称为Ａ型者２５例;增强后扫描时间延至５ｍｉｎ仍未见强化（差值＜１０ＨＵ）为Ｂ型１１例,增强后开始轻微强化,呈逐渐上升趋势（Ｃ型）９例。与术后病理比较：周围型肺癌（２２例）强化方式以Ａ型为主,其敏感度为９１％、特异度为７８％。结核球（１４例）以Ｂ型强化方式为主,其敏感度为７１％,特异度为８８％。炎性假瘤（４例）以Ａ、Ｃ型为主,血管瘤（２例）以Ｃ型为主,畸胎瘤（３例）Ａ、Ｂ、Ｃ型均有。结论：孤立性肺结节病变以周围型肺癌及结核球为多见,薄层动态ＣＴ扫描强化方式表现不同,可提高病变诊断阳性率     

腹腔镜门静脉高压症外科治疗发展与新断流术

在当前微创外科时代,门奇静脉断流术取得一系列大的进展,例如,选择性贲门周围血管离断术的提出和应用、断流术时行脾切除术的适应证与禁忌证,以及新一代外科手术器械和腹腔镜技术在断流术和脾切除术中的应用等。实践表明,腹腔镜脾切除术贲门周围血管离断术是安全、简单和有效的手术术式,肝硬化门静脉高压症患者也适用。为了进一步证实这种新门奇静脉断流术的疗效,今后有待开展前瞻性、随机性、大样本的研究。