利用纤维素酶辅助提取紫菜藻红蛋白的研究

利用纤维素酶辅助破壁,显著提高了紫菜藻红蛋白的提取率。比较了纤维素酶结合反复冻融破壁、超声波破壁、自溶破壁等各种方法的提取效果,最终确定选用纤维素酶+反复冻溶破壁法提取藻红蛋白。并确定提取条件:添加纤维素酶50μl/g干紫菜,于4℃、pH 7.0条件下作用2 h,反复冻融3次,在此条件下提取率达1.55%,纯度1.36。室温、光照、Fe2+、Zn2+和Cu2+等金属离子存在均会破坏藻红蛋白。

在实验教学中实现深度学习

小学科学应倡导探究式学习。在基础教育课程改革的背景下,要深度开展小学科学探究活动,就要优化探究过程中的细节,让前概念进阶化、课堂生成可视化、实验记录共享化、教学评价多元化。本文既建构了“四化”的宏观模型,又以《谁轻谁重》为例,从微观角度阐释了实现深度学习的具体方法,让小学科学探究落在实处。

剖析探究活动“四个环节”设计的内涵

聚焦、探索、研讨、拓展为科学探究活动的四个基本环节。笔者认为,在科学实践的视野下,探究教学是探索、研讨主导下的“四个环节”协同发展、螺旋上升的过程。与此同时,学生的知识建构经历感知、认同、内化、应用多元循环。根据小学科学课堂教学的突出特点,笔者剖析了“四个环节”的内涵,并结合《机械摆钟》《测量力的大小》这两个课例,对基于“四个环节”教学方式的实践进行详细阐述,以期充分发挥科学探究的作用,使学生建构准确、完善的科学知识体系。

Initial 12-h Operative Fluid Volume is an Independent Risk Factor for Pleural Effusion after Hepatectomy

Pleural effusion after hepatectomy is associated with significant morbidity and prolonged hospital stays.Several studies have addressed the risk factors for postoperative pleural effusion.However,there are no researches concerning the role of the initial 12-h operative fluid volume.The aim of this study was to evaluate whether the initial 12-h operative fluid volume during liver resection is an independent risk factor for pleural effusion after hepatectomy.In this study,we retrospectively analyzed clinical data of 470 patients consecutively undergoing elective hepatectomy between January 2011 and December 2012.We prospectively collected and retrospectively analyzed baseline and clinical data,including preoperative,intraoperative,and postoperative variables.Univariate and multivariate analyses were carried out to identify whether the initial 12-h operative fluid volume was an independent risk factor for pleural effusion after hepatectomy.The multivariate analysis identified 2 independent risk factors for pleural effusion：operative time [odds ratio（OR）=10.2] and initial 12-h operative fluid volume（OR=1.0003）.Threshold effect analyses revealed that the initial 12 h operative fluid volume was positively correlated with the incidence of pleural effusion when the initial 12-h operative fluid volume exceeded 4636 m L.We conclude that the initial 12-h operative fluid volume during liver resection and operative time are independent risk factors for pleural effusion after hepatectomy.Perioperative intravenous fluids should be restricted properly.

基于MRI的LI-RADS 2018版评价肝癌介入术后肿瘤活性的研究

目的探讨基于MRI采用肝脏影像报告和数据系统(LI-RADS)2018版的疗效评价标准(TRA)评估肝细胞癌介入术后肿瘤活性的效能。方法回顾性搜集2017年1月至2021年6月在介入术后行MRI增强扫描的74例(92个病灶)肝癌患者。由两位放射科医师根据2018版LI-RADS TRA评估每个病灶在MRI图像上的征象及疗效分类(肿瘤无存活、肿瘤存活、肿瘤存活判断困难),并评估两位医师分类结果的一致性;计算该疗效标准诊断肝癌残余活灶的效能。结果两位阅片医师采用LI-RADS TRA评价肝癌介入术后疗效分类的一致性良好,Kappa值为0.782。92个病灶中,有39个、33个和20个病灶分别评价为肿瘤无存活、肿瘤存活、肿瘤存活判断困难,后者经证实65.0%(13/20)为肿瘤活灶。依据LI-RADS TRA评估为治疗后肿瘤存活的灵敏度、特异度、阳性预测值、阴性预测值及准确率分别为67.3%、100%、100%、72.9%、82.6%。结论基于MRI图像采用LI-RADS TRA评价肝癌介入治疗后肿瘤活灶的灵敏度和阴性预测值相对较低,特异度和阳性预测值高。分类为“治疗后肿瘤存活判断困难”的病灶经证实多为肿瘤活灶,需密切随访观察或进一步治疗。