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2024-03-07 20:41:09

国家普通话水平测试在线报名系统

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普通话水平测试（对应试人运用普通话程度的口语考试）_百度百科

平测试（对应试人运用普通话程度的口语考试）_百度百科网页新闻贴吧知道网盘图片视频地图文库资讯采购百科百度首页登录注册进入词条全站搜索帮助首页秒懂百科特色百科知识专题加入百科百科团队权威合作下载百科APP个人中心普通话水平测试是一个多义词，请在下列义项上选择浏览（共2个义项）展开添加义项普通话水平测试播报讨论上传视频对应试人运用普通话程度的口语考试收藏查看我的收藏0有用+10普通话水平测试（Putonghua Shuiping Ceshi；PSC）是对应试人运用普通话的规范程度、熟练程度的口语考试。考试形式为口试。普通话水平等级分为三级六等，即一、二、三级，每个级别再分出甲乙两个等次；一级甲等为最高，三级乙等为最低。普通话水平测试不是口才的评定，而是对应试人掌握和运用普通话所达到的规范程度的测查和评定，是应试人的汉语标准语测试。应试人在运用普通话口语进行表达过程中所表现的语音、词汇、语法规范程度，是评定其所达到的水平等级的重要依据。2022年11月，教育部、国家语言文字工作委员会发布《中小学生普通话水平测试等级标准及测试大纲》（试行），于2022年12月15日起试行。 [7]中文名普通话水平测试外文名Putonghua Shuiping Ceshi缩写PSC类别资格考试等级三级六等证书《国家普通话水平测试等级证书》目录1相关规定2报名考试▪报考时间▪报名入口▪特别提醒▪报名流程▪报名条件▪分数查询3要求4等级▪一级甲等▪一级乙等▪二级甲等▪二级乙等▪三级甲等▪三级乙等5大纲6试卷▪1. 读单音节字词100个▪2. 读双音节词语50个▪3. 朗读▪4. 说话7证书8条例修改9相关规范相关规定播报编辑普通话是现代汉语的标准语。由国家语言文字工作委员会和国家教育委员会、广播电影电视部颁布的，《普通话水平测试等级标准（试行）》。省、市级测试中心、测试站只能授予一级乙等以下（含一级乙等）的资格证书。考一级甲等，需要去国家语委测试中心考试，或者省级测试站报送国家语委测试站进行复审通过，方能授予一级甲等。（国语[1997]64号）把普通话水平分为三个级别（一级可称为标准的普通话，二级可称为比较标准的普通话，三级可称为一般水平的普通话），每个级别内划分甲、乙两个等次。三级六等是普通话水平测试中评定应试人普通话水平等级的依据。普通话水平等级等级详情一级（标准的普通话）一级甲等（测试得分：97分-100分之间）朗读和自由交谈时，语音标准，词语、语法正确无误，语调自然，表达流畅。一级乙等（测试得分：92分-96.99分之间）朗读和自由交谈时，语音标准，词语、语法正确无误，语调自然，表达流畅。偶然有字音、字调失误。二级（比较标准的普通话）二级甲等（测试得分：87分-91.99分之间）朗读和自由交谈时，声韵调发音基本标准，语调自然，表达流畅。少数难点音有时出现失误。词语、语法极少有误。二级乙等（测试得分：80分-86.99分之间）朗读和自由交谈时，个别调值不准，声韵母发音有不到位现象。难点音失误较多。方言语调不明显。有使用方言词、方言语法的情况。三级（一般水平的普通话）三级甲等（测试得分：70分-79.99分之间）朗读和自由交谈时，声韵母发音失误较多，难点音超出常见范围，声调调值多不准。方言语调较明显。词语、语法有失误。三级乙等（测试得分：60分-69.99分之间）朗读和自由交谈时，声韵调发音失误多，方音特征突出。方言语调明显。词语、语法失误较多。外地人听其谈话有听不懂的情况。普通话水平测试等级证书是证明应试人普通话水平有效凭证，证书由国家语言文字工作委员会统一印制。普通话一级乙等以下成绩的证书由省（直辖市）级语言文字工作委员会加盖印章后颁发，普通话一级甲等的证书须经国家普通话水平测试中心审核并加盖国家普通话水平测试中心印章后方为有效。有效的普通话水平测试等级证书全国通用。2021年11月，教育部颁布新修订的《普通话水平测试管理规定》 [6]，明确将普通话水平测试等级证书的颁发机构由省级语言文字工作办事机构统一变化为国家测试机构，普通话一级甲等需经国家测试认定机构，一级乙等及以下由省级测试机构认定。《规定》将于2022年1月1日起正式实施。 [5]报名考试播报编辑报考时间各地考试时间不统一，以当年公布的报名时间考试时间为准。报名入口广电系统的播音员、节目主持人的普通话测试由广电行政管理部门统一组织报名；非统一组织的社会各界各类人员的普通话水平测试每2个月组织一次，由应试人本人到市测试中心报名。报名时应携带身份证、工作证（学生证）和近期二寸免冠报名照一张。各区县语言文字工作委员会办公室（以下简称语委办）组织本区县内的教师和其他有关人员进行普通话水平测试，一般每年组织两场。测试前，由区县语委办统一到市测试中心报名。具体报名方法请咨询全国普通话培训测试资源网或各地语委办。特别提醒根据国家语委办的文件规定，报名参加普通话测试的人员，必须在前5个月内未参加过普通话水平测试。即两次测试时间间隔应大于5个月。报名流程普通话资格考试可在网上报名，报考人员须在网上提交报名申请，或者到报名现场实地报名，再得到报考资格确认后，方可参加考试。报名条件1. 中小学教师；2. 中等师范学校教师和高等院校文科教师；3. 师范院校毕业生（高等师范里，首先是文科类毕业生）；4. 广播、电视、电影、戏剧，以及外语、旅游等高等院校和中等职业学校相关专业的教师和毕业生；5. 各级广播电台、电视台的播音员、节目主持人；6. 从事电影、电视剧、话剧表演和影视配音的专业人员；7. 其他应当接受普通话水平测试的人员和自愿接受普通话水平测试的人员。分数查询登录国家普通话水平测试网查询。 [1]要求播报编辑根据各行业的规定，有关从业人员的普通话水平达标要求如下：中小学及幼儿园、校外教育单位的教师，普通话水平不低于二级，其中语文教师不低于二级甲等，普通话语音教师不低于一级；高等学校的教师，普通话水平不低于三级甲等，其中现代汉语教师不低于二级甲等，普通话语音教师不低于一级；对外汉语教学教师，普通话水平不低于二级甲等。报考中小学、幼儿园教师资格的人员，普通话水平不低于二级。师范类专业以及各级职业学校的与口语表达密切相关专业的学生，普通话水平不低于二级。国家公务员，普通话水平不低于三级甲等。国家级和省级广播电台、电视台的播音员、节目主持人，普通话水平应达到一级甲等，其他广播电台、电视台的播音员、节目主持人的普通话达标要求按国家广播电影电视总局的规定执行。话剧、电影、电视剧、广播剧等表演、配音演员，播音、主持专业和影视表演专业的教师、学生，普通话水平不低于一级。公共服务行业的特定岗位人员（如广播员、解说员、话务员等），普通话水平不低于二级甲等。普通话水平应达标人员的年龄上限以有关行业的文件为准。等级播报编辑国家语言文字工作委员会颁布的《普通话水平测试等级标准》是划分普通话水平等级的全国统一标准。普通话水平等级分为三级六等，即一、二、三级，每个级别再分出甲乙两个等次；一级甲等为最高，三级乙等为最低。应试人的普通话水平根据在测试中所获得的分值确定。 [1]普通话水平测试等级标准如下：一级甲等朗读和自由交谈时，语音标准，语汇、语法正确无误，语调自然，表达流畅。测试总失分率在3%以内。一级乙等朗读和自由交谈时，语音标准，语汇、语法正确无误，语调自然，表达流畅。偶有字音、字调失误。测试总失分率在8%以内。二级甲等朗读和自由交谈时，声韵调发音基本标准，语调自然，表达流畅。少数难点音（平翘舌音、前后鼻尾音、边鼻音等）有时出现失误。语汇、语法极少有误。测试总失分率在13%以内。二级乙等朗读和自由交谈时，个别调子不准，声韵母发音有不到位现象。难点音较多（平翘舌音、前后鼻尾音、边鼻音、fu-hu、z-zh-j、送气不送气、i-ü不分、保留浊塞音、浊塞擦音、丢介音、复韵母单音化等），失误较多。方言语调不明显，有使用方言词、方言语法的情况。测试总失分率在20%以内。三级甲等甲等朗读和自由交谈时，声韵母发音失误较多，难点音超出常见范围，声调调值多不准。方言语调明显。语汇、语法有失误。测试总失分率在30%以内。三级乙等朗读和自由交谈时，声韵调发音失误多，方音特征突出。方言语调明显。语汇、语法失误较多。外地人听其谈话有听不懂的情况。测试总失分率在40%以内。大纲播报编辑《普通话水平测试（PSC）大纲》由国家语言文字工作委员会颁布，是进行普通话水平测试的全国统一大纲。普通话水平测试试卷内容全部来自大纲。试卷播报编辑普通话水平测试试卷由四个测试项构成，总分为100分。1、读单音节字词100个，限时3分30秒，占10分。目的考查应试人普通话声母、韵母和声调的发音。2、读双音节词语50个，限时2分30秒，占20分。目的是除了考查应试人声、韵、调的发音外，还要考查上声变调、儿化韵和轻声的读音。3、400字短文朗读，限时4分钟，占30分。目的是考查应试人使用普通话朗读书面材料的能力，重点考查语音、语流音变、语调等。4、说话，时间3分钟，占40分。目的是考查应试人在无文字凭借的情况下说普通话所达到的规范程度。1. 读单音节字词100个排除轻声、儿化音节目的：考察应试人声母、韵母、声调的发音。要求：100个音节里，每个声母出现一般不少于3次，方言里缺少的或容易混淆的酌量增加1-2次；每个韵母的出现一般不少于2次，方言里缺少的或容易混淆的韵母酌量增加1-2次。字音声母或韵母相同的要隔开排列。不使相邻的音节出现双声或叠韵的情况。评分：此项成绩占总分的10%，即10分。读错一个字的声母、韵母或声调扣0.1分。读音有缺陷每个字扣0.05分。一个字允许读两遍，即应试人发觉第一次读音有口误时可以改读，按第二次读音评判。限时：3.5分钟。超时扣分（超时1分钟以内扣0.5分，超时1分钟以上扣1分）。 [2]读音有缺陷指读1单音节字词和2读双音节词语两项记评。读音有缺陷在1项内主要是指声母的发音部位不准确，但还不是把普通话里的某一类声母读成另一类声母，比如舌面前音j、q、x读得太接近z、c、s；或者是把普通话里的某一类声母的正确发音部位用较接近的部位代替，比如把舌面前音j、q、x读成舌叶音；或者读翘舌音声母时舌尖接触或接近上腭的位置过于靠后或靠前，但还没有完全错读为舌尖前音等；韵母读音的缺陷多表现为合口呼、撮口呼的韵母圆唇度明显不够，语感差；或者开口呼的韵母开口度明显不够，听感性质明显不符；或者复韵母舌位动程明显不够等；声调调形、调势基本正确，但调值明显偏低或偏高，特别是四声的相对高点或低点明显不一致的，判为声调读音缺陷；这类缺陷一般是成系统的，每个声调按5个单音错误扣分。1和2两项里都有同样问题的，两项分别都扣分。2. 读双音节词语50个目的：除考察应试人声母、韵母和声调的发音外，还要考察上声变调、儿化韵和轻声的读音。要求：50个双音节可视为100个单音节，声母、韵母的出现次数大体与单音节字词相同。此外，上声和上声相连的词语不少于2次，上声和其他声调相连不少于4次；轻声不少于3次；儿化韵不少于4次（arurierüer），词语的排列要避免同一测试项的集中出现。评分：此项成绩占总分的20%，即20分。读错一个音节的声母、韵母或声调扣0.2分。读音有明显缺陷每次扣0.1分。限时：2.5分钟。超时扣分（超时1分钟以内扣0.5分，超时1分钟以上扣一分）。 [3]读音有缺陷所指的除跟1项内所述相同的以外，儿化韵读音明显不合要求的应列入。1和2两项测试，其中有一项或两项分别失分在10%的，即1题失分1分，或2题失分2分即判定应试人的普通话水平不能进入一级。应试人有较为明显的语音缺陷的，即使总分达到一级甲等也要降等，评定为一级乙等。3. 朗读朗读从《测试大纲》第五部分朗读材料（1-60号）中任选。目的：考察应试人用普通话朗读书面材料的水平，重点考察语音、连读音变（上声、“一”、“不”），语调（语气）等项目。计分：此项成绩占总分的30%。即30分。对每篇材料的前400字（不包括标点）做累积计算，每次语音错误扣0.1分，漏读一个字扣0.1分，不同程度地存在方言语调一次性扣分（问题突出扣3分；比较明显，扣2分；略有反映，扣1.5分。停顿、断句不当每次扣1分；语速过快或过慢一次性扣2分）。限时：4分钟。超过4分30秒以上扣1分。说明：朗读材料（1-50）各篇的字数略有出入，为了做到评分标准一致，测试中对应试人选读材料的前400个字（每篇400字之后均有标志）的失误做累积计算；但语调、语速的考察应贯穿全篇。从测试的要求来看，应把提供应试人做练习的50篇作品作为一个整体，应试前通过练习全面掌握。4. 说话目的：考察应试人在没有文字凭借的情况下，说普通话的能力和所能达到的规范程度。以单向说话为主，必要时辅以主试人和应试人的双向对话。单向对话：应试人根据抽签确定的话题，说4分钟（不得少于3分钟，说满4分钟主试人应请应试人停止）。评分：此项成绩占总分的40%，即40分。其中包括：⑴语音面貌占20%，即20分。其中档次为：一档20分语音标准；二档18分语音失误在10次以下，有方音不明显；三档16分语音失误在10次以下，但方音比较明显；或方音不明显，但语音失误大致在10次-15次之间；四档14分语音失误在10次-15次之间，方音比较明显；五档10分语音失误超过15次，方音明显；六档8分语音失误多，方音重。语音面貌确定为二档（或二档以下）即使总积分在96以上，也不能入一级甲等；语音面貌确定为五档的，即使总积分在87分以上，也不能入二级甲等；有以上情况的，都应在等内降等评定。⑵词汇语法规范程度占10%。计分档次为：一档10分词汇、语法合乎规范；二档8分偶有词汇或语法不符合规范的情况；三档6分词汇、语法屡有不符合规范的情况；⑶自然流畅程度占10%，即10分。计分档次为：一档10分自然流畅；二档8分基本流畅，口语化较差（有类似背稿子的表现）；三档6分语速不当，话语不连贯；说话时间不足，必须主试人用双向谈话加以弥补。试行阶段采用以上评分办法，随着情况的变化应适当增加说话评分的比例。证书播报编辑应试者经过测试，即可获得《国家普通话水平测试等级证书》。《国家普通话水平测试等级证书》由国家语言文字工作委员会统一制作。证书内将记录应试者的测试成绩和相应的等级。1997年出台的《普通话水平测试管理办法》（试行）规定，“普通话水平等级证书有效期为5年”，超过期限将重新考核认定。2003年修订的《普通话水平测试管理办法》（正式），取消了关于普通话水平等级证书有效期的提法，这就是说，普通话水平等级证书全国通用、无有效期限制。自2011年起，普通话证书样式进行了改版，旧版中包含出生年月，新版取消；旧版无身份证号码，新版增加；新版增加测试时间。均盖有国家语言文字工作委员会公章及测试中心的钢印。并由之前的本状改成纸状，且附有证书外壳。条例修改播报编辑2021年12月，教育部颁布新修订的《普通话水平测试管理规定》，明确将普通话水平测试等级证书的颁发机构由省级语言文字工作办事机构统一变更为国家测试机构，普通话一级甲等须经国家测试机构认定，一级乙等及以下由省级测试机构认定。《规定》将于2022年1月1日起正式施行。 [4]相关规范播报编辑2022年11月，教育部、国家语言文字工作委员会发布《中小学生普通话水平测试等级标准及测试大纲》（试行），该规范将于2022年12月15日起试行。 [7]新手上路成长任务编辑入门编辑规则本人编辑我有疑问内容质疑在线客服官方贴吧意见反馈投诉建议举报不良信息未通过词条申诉投诉侵权信息封禁查询与解封©2024 Baidu 使用百度前必读 | 百科协议 | 隐私政策 | 百度百科合作平台 | 京ICP证030173号京公网安备110000020000

国家普通话水平测试网

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普通话水平测试（PSC)简介

发布者：楼红军发布时间：2019-04-01浏览次数：60

普通话水平测试（简称为PSC）是我国为加快共同语普及进程、提高全社会普通话水平而设置的一种语言测试制度。它属于语言测试的范畴，又不同一般意义的语言测试：普通话水平测试是由政府专门机构主持的一项测试。国家语委普通话培训测试中心及地方（省、自治区、直辖市）普通话培训测试中心具体负责实施。非普通话培训测试中心组织的测试结果，一律不作为普通话水平的凭证。普通话水平测试是资格证书测试。有关行业对本行业从业人员提出了相应的普通话水平等级要求，《普通话水平等级证书》是从业人员普通话水平的凭证，在全国范围内通用。普通话水平测试是一种口语测试，全部测试内容均以口头方式进行。普通话水平测试不是口才的评定，而是对应试人掌握和运用普通话所达到的规范程度的测查和评定。经报名核准后，应试者应在规定的日期，凭本人的准考证和身份证，进入指定的考场，并按指定试卷上的内容进行测试。每个试场有2-3位测试员负责对应试者的普通话水平进行判定。总时间在15分钟左右。

地址：上海市临港新城沪城环路999号邮编：201306

原发性硬化性胆管炎（PSC） - 肝脏及胆道疾病 - MSD诊疗手册专业版

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兽医手册（仅有英文版）

专业版

肝脏及胆道疾病

胆囊和胆管疾病

原发性硬化性胆管炎（PSC）

在该主题中

本章节的其他主题

胆汁功能的概述

无结石性胆绞痛

急性胆囊炎

AIDS相关的胆管病

慢性胆囊炎

胆管结石和胆管炎

胆石症

胆囊切除术后综合征

原发性硬化性胆管炎（PSC）

硬化性胆管炎

IgG4相关的硬化性胆管炎

胆囊及胆管肿瘤

原发性硬化性胆管炎（PSC）

作者：

Yedidya Saiman

, MD, PhD, Lewis Katz School of Medicine, Temple University

医学审查 8月 2023

看法进行患者培训

病因

症状和体征

诊断

治疗

关键点

原发性硬化性胆管炎（PSC）是胆管节段性的炎症、纤维化和狭窄，病因不明。80％的PSC患者也有炎症性肠病，通常是溃疡性结肠炎。其他伴随的情况有结缔组织疾病、自身免疫性疾病、免疫缺陷综合征，有时合并机会性感染。乏力和瘙痒症状隐匿发生，进行性加重。通过胆管造影术（磁共振胰胆管造影术[MRCP]或内镜逆行胰胆管造影[ERCP]）进行诊断。终末期患者有肝移植指征。（参见胆管功能概述胆汁功能的概述肝脏每天生成500~600mL胆汁。胆汁与血浆等渗，主要成分有水、电解质和有机成分包括胆汁酸盐、磷脂（主要是卵磷脂）、胆固醇、胆红素、其他内源性生成物以及摄取的化合物，如调节胃肠功能的蛋白和药物或其代谢产物。胆红素是来自衰老红细胞的血红素的降解产物，使胆汁呈黄绿色。... Common.TooltipReadMore 。） PSC是硬化性胆管炎最常见的类型大多数（70％）PSC患者是男性。平均诊断年龄为40岁。原发性硬化性胆管炎的病因学病因尚不明确，但是70％的患者原发性硬化性胆管炎（PSC）与炎症性肠病炎症性肠病概述炎症性肠病（IBD），包括克罗恩病和溃疡性结肠炎，表现为反复发作和缓解的不同状态，均以胃肠道不同部位的慢性炎症为特征，这些炎症可引起腹泻和腹痛。炎症由胃肠黏膜中细胞介导免疫反应所致。炎症性肠病的确切病因尚不明，但有证据表明，在有多因素遗传易感性患者肠道中，正常菌群所诱发的异常免疫反应与该病有... Common.TooltipReadMore 有关 (1 病因参考文献原发性硬化性胆管炎（PSC）是胆管节段性的炎症、纤维化和狭窄，病因不明。80％的患者也有炎症性肠病，通常是溃疡性结肠炎。其他伴随的情况有结缔组织疾病、自身免疫性疾病、免疫缺陷综合征，有时合并机会性感染。乏力和瘙痒症状隐匿发生，进行性加重。通过胆管造影术（磁共振胰胆管造影术[MRCP]或内镜逆行胰胆管造影[ERCP]）进行诊断。终末期患者有肝移植指征。（亦见胆管功能概述） PSC是硬化性胆管炎最常见的类型大多数（70％）PSC患者是男... Common.TooltipReadMore )。约 5% 的患者溃疡性结肠炎溃疡性结肠炎溃疡性结肠炎指发生于结肠黏膜慢性炎症性、溃疡性疾病，典型症状为血性腹泻。可出现肠道外症状，尤其关节炎。病者较健康者患结肠癌远期风险更高。诊断依靠结肠镜。治疗方法包括：5-ASA、糖皮质激素、免疫调节剂、生物制剂、抗生素，有时需要手术。（参见炎症性肠病概述）。溃疡性结肠炎通常始于直肠。可局限于直肠（溃疡性直肠炎）或向近端扩展，有时累及全结肠。累及全结肠情况较罕见。溃疡性结肠炎炎症累及黏膜至黏膜下层，正常和受累组织之间的界限清楚。仅... Common.TooltipReadMore 约 1% 与克罗恩病克罗恩病克罗恩病是一种慢性透壁性炎症性肠病，通常累及末端回肠和结肠，但也可发生在胃肠道任何部分。症状包括腹泻和腹痛。可发生脓肿、内瘘、外瘘和肠梗阻。可出现肠道外表现，特别是关节炎。诊断依靠结肠镜检查和影像学检查。可用5-ASA、皮质类固醇、免疫调节剂、抗细胞因子、抗生素和手术治疗。（参加炎症性肠病概述）。克罗恩病最初黏膜病变为隐窝炎症和脓肿，然后发展为极小的局灶性口疮样溃疡。这些黏膜病变可向深部纵向和横向的溃疡发展，伴黏膜水肿，形成特征... Common.TooltipReadMore 发展为原发性硬化性胆管炎 (PSC)。这种关联和存在若干自身抗体（例如，抗核抗体和核周抗中性粒细胞抗体[pANCA]）提示免疫介导的机制。T细胞似乎参与胆管的破坏，这意味着细胞免疫的紊乱。多个家庭成员发生疾病的趋势，以及与自身免疫性疾病相关性的人类HLAB8和HLADR3较高频率出现提示了遗传易感性。未知的触发因素（例如细菌感染、缺血性导管损伤）可能会促进遗传易感人群发生 PSC。病因参考文献 1.Bowlus CL, Arrivé L, Bergquist A, et al: AASLD practice guidance on primary sclerosing cholangitis and cholangiocarcinoma.Hepatology 77(2):659-702, 2023. doi: 10.1002/hep.32771 原发性硬化性胆管炎的症状和体征通常起病隐匿，进行性乏力和瘙痒。高达40%的患者会出现腹痛、瘙痒、腹泻、黄疸、疲劳和发烧等症状 (1 症状和体征参考原发性硬化性胆管炎（PSC）是胆管节段性的炎症、纤维化和狭窄，病因不明。80％的患者也有炎症性肠病，通常是溃疡性结肠炎。其他伴随的情况有结缔组织疾病、自身免疫性疾病、免疫缺陷综合征，有时合并机会性感染。乏力和瘙痒症状隐匿发生，进行性加重。通过胆管造影术（磁共振胰胆管造影术[MRCP]或内镜逆行胰胆管造影[ERCP]）进行诊断。终末期患者有肝移植指征。（亦见胆管功能概述） PSC是硬化性胆管炎最常见的类型大多数（70％）PSC患者是男... Common.TooltipReadMore )。可有脂肪泻和脂溶性维生素的缺乏。持续的黄疸预示病情严重。75%的患者可发生有症状的胆囊结石胆石症胆石症是指胆囊内有一个或多个结石（胆结石）存在。在发达国家，约10%的成人和20％的>65岁人群有胆结石。胆结石可以无症状，最常见的症状是胆绞痛，但不会引起消化不良或高脂食物不耐受。较严重的并发症包括胆囊炎、胆管梗阻（通常是胆管结石引起），有时伴感染（胆管炎）和胆石性胰腺炎。通常根据B超作出诊断。如果胆石症引起临床症状或并发症，有必要行胆囊切除术。（亦见胆管功能概述）... Common.TooltipReadMore 和胆管结石胆管结石和胆管炎胆管结石是指胆管内存在结石，该结石可能来源于胆囊或胆管本身。可造成胆绞痛、胆管梗阻、胆石性胰腺炎或胆管炎（胆管感染和炎症）。随后，胆管炎可导致胆管狭窄、胆汁淤滞和胆管结石。诊断通常需要通过磁共振胰胆管造影术或内窥镜逆行胰胆管造影术进行可视化。有指征行早期内镜或手术减压。（参见胆管功能概述）结石包括：原发性结石（通常是棕色胆色素结石）形成于胆管内。... Common.TooltipReadMore (1 症状和体征参考原发性硬化性胆管炎（PSC）是胆管节段性的炎症、纤维化和狭窄，病因不明。80％的患者也有炎症性肠病，通常是溃疡性结肠炎。其他伴随的情况有结缔组织疾病、自身免疫性疾病、免疫缺陷综合征，有时合并机会性感染。乏力和瘙痒症状隐匿发生，进行性加重。通过胆管造影术（磁共振胰胆管造影术[MRCP]或内镜逆行胰胆管造影[ERCP]）进行诊断。终末期患者有肝移植指征。（亦见胆管功能概述） PSC是硬化性胆管炎最常见的类型大多数（70％）PSC患者是男... Common.TooltipReadMore )。有些患者无症状，直到病程晚期才出现症状，以肝脾大或肝硬化肝硬化肝硬化（cirrhosis）是纤维化的晚期阶段已导致正常肝组织结构广泛破坏。肝硬化特征是致密纤维组织包绕再生结节。肝硬化可经历多年的无症状期或有食欲减退、易疲劳、体重下降等非特异表现。晚期表现为门脉高压、腹水、肝性脑病，以及失代偿时发生的肝衰竭。尽管在极少数情况下需要进行肝活检，但通常使用无创成像进行诊断。管理包括支持性护理和对致病性肝病的治疗。肝硬化是全球第14大死亡原因。... Common.TooltipReadMore 为首发症状。原发性硬化性胆管炎 (PSC) 往往会缓慢而无情地进展。终末阶段涉及失代偿性肝硬化，门脉高压门静脉高压门静脉高压是门静脉的压力升高。它通常由肝硬化（在北美）、血吸虫病（在流行地区）或肝血管异常引起。它引起食管静脉曲张和门－体分流性脑病。诊断主要是根据临床标准，常结合影像学检查和内镜检查。治疗包括通过内镜、药物或二者一起预防消化道出血，有时通过门腔静脉分流或肝移植预防出血。（也可以参见肝脏结构和功能和肝脏疾病患者的评估.) 肠系膜上静脉和脾静脉汇合形成门静脉，将来自腹腔内消化道、脾脏和胰腺的血液引流入肝脏。在网状内皮细胞排列的血液... Common.TooltipReadMore ，腹水腹水腹水是指腹腔内游离的液体。最常见的原因是门静脉高压。症状通常是由腹腔膨胀所致。通过体格检查、超声或CT可以诊断。治疗包括限钠饮食、利尿和治疗性穿刺。腹水可以出现感染（自发性细菌性腹膜炎），通常伴有疼痛和发热。感染的诊断依靠腹水的分析和培养，需用抗生素治疗。慢性肝病可以引起腹水，有时急性肝病也可以引起。与肝脏无关的情况也能引起腹水。肝脏原因引起腹水包括下列情况：门静脉高压（>... Common.TooltipReadMore 和肝功能衰竭急性肝功能衰竭引发急性肝功能衰竭最常见的是药物和肝炎病毒。主要临床表现为黄疸、凝血功能障碍和脑病。诊断是基于临床的。治疗主要采取支持疗法，有时会采用肝移植和/或特殊治疗（如针对对乙酰氨基酚毒性的N-乙酰半胱氨酸）。（也可以参见肝脏结构和功能和肝脏疾病患者的评估.) 肝功能衰竭的分类方法有多种，但目前尚无一种普遍认可的分类方法（见表肝衰竭的分类）。总体而言，急性肝衰竭最常见的病因为... Common.TooltipReadMore 。尽管PSC和炎症性肠病炎症性肠病概述炎症性肠病（IBD），包括克罗恩病和溃疡性结肠炎，表现为反复发作和缓解的不同状态，均以胃肠道不同部位的慢性炎症为特征，这些炎症可引起腹泻和腹痛。炎症由胃肠黏膜中细胞介导免疫反应所致。炎症性肠病的确切病因尚不明，但有证据表明，在有多因素遗传易感性患者肠道中，正常菌群所诱发的异常免疫反应与该病有... Common.TooltipReadMore 有关，但两者病程是独立的。溃疡性结肠炎溃疡性结肠炎溃疡性结肠炎指发生于结肠黏膜慢性炎症性、溃疡性疾病，典型症状为血性腹泻。可出现肠道外症状，尤其关节炎。病者较健康者患结肠癌远期风险更高。诊断依靠结肠镜。治疗方法包括：5-ASA、糖皮质激素、免疫调节剂、生物制剂、抗生素，有时需要手术。（参见炎症性肠病概述）。溃疡性结肠炎通常始于直肠。可局限于直肠（溃疡性直肠炎）或向近端扩展，有时累及全结肠。累及全结肠情况较罕见。溃疡性结肠炎炎症累及黏膜至黏膜下层，正常和受累组织之间的界限清楚。仅... Common.TooltipReadMore 可在PSC之前数年出现，伴有PSC时通常病情较轻。同样，全结肠切除术也不能改变PSC的病程。不论PSC是否行肝移植肝移植肝移植是第二常见的实体器官移植。（参阅移植概述）肝移植的适应证包括：肝硬化（占美国肝移植的70％;其中10％到20％是由丙型肝炎引起的）暴发性坏死性肝炎（约8%）肝细胞肝癌（约7%） Common.TooltipReadMore ，PSC和炎症性肠病两种疾病共存增加了结直肠癌的发病率。胆管癌胆囊及胆管肿瘤胆囊和胆管肿瘤可引起肝外胆管梗阻。可以无症状，但通常有全身或反映胆管梗阻的症状。诊断基于超声检查加上CT胆管成像或磁共振胆胰管成像。预后通常很差。机械性胆汁引流可减轻胆管梗阻造成的瘙痒、反复败血症和疼痛。（亦见胆管功能概述）胆管癌（cholangiocarcinomas）和其他胆管肿瘤少见（发生率1～2/10万），通常是恶性的。胆管癌主要发生在肝外胆管：60％～70％发生在肝门周围（Klatskin肿瘤），25％发生在远端肝管，其... Common.TooltipReadMore 10% 到 15% 的患者会出现这种情况（2 症状和体征参考原发性硬化性胆管炎（PSC）是胆管节段性的炎症、纤维化和狭窄，病因不明。80％的患者也有炎症性肠病，通常是溃疡性结肠炎。其他伴随的情况有结缔组织疾病、自身免疫性疾病、免疫缺陷综合征，有时合并机会性感染。乏力和瘙痒症状隐匿发生，进行性加重。通过胆管造影术（磁共振胰胆管造影术[MRCP]或内镜逆行胰胆管造影[ERCP]）进行诊断。终末期患者有肝移植指征。（亦见胆管功能概述） PSC是硬化性胆管炎最常见的类型大多数（70％）PSC患者是男... Common.TooltipReadMore ）。症状和体征参考 1.Kaplan GG, Laupland KB, Butzner D, et al: The burden of large and small duct primary sclerosing cholangitis in adults and children: a population-based analysis.Am J Gastroenterol 102(5):1042-1049, 2007. doi: 10.1111/j.1572-0241.2007.01103.x 2.Tabibian JH, Ali AH, Lindor KD: Primary sclerosing cholangitis, part 2: Cancer risk, prevention, and surveillance.Gastroenterol Hepatol (NY). 14(7):427-432, 2018.PMID: 30166959 原发性硬化性胆管炎的诊断磁共振胆胰管成像（MRCP）有不明原因异常的患者怀疑原发性硬化性胆管炎（PSC）肝脏检查实验室检查实验室检查一般对于下列情况是有用的：发现肝功能不全评估肝脏损害的严重程度监测疾病进程和评价疗效完善诊断 Common.TooltipReadMore ，尤其是那些有炎症性肠病炎症性肠病概述炎症性肠病（IBD），包括克罗恩病和溃疡性结肠炎，表现为反复发作和缓解的不同状态，均以胃肠道不同部位的慢性炎症为特征，这些炎症可引起腹泻和腹痛。炎症由胃肠黏膜中细胞介导免疫反应所致。炎症性肠病的确切病因尚不明，但有证据表明，在有多因素遗传易感性患者肠道中，正常菌群所诱发的异常免疫反应与该病有... Common.TooltipReadMore 。典型的胆汁淤积表现：碱性磷酸酶和gamma‑谷氨酰转移酶(GGT)通常比氨基转移酶升高更明显。gamma‑球蛋白和IgM水平趋于升高。抗he抗体和PANCA通常为阳性。抗线粒体抗体在原发性胆汁性胆管炎原发性胆汁性胆管炎（PBC）原发性胆汁性胆管炎（primary biliary cirrhosis，PBC，既往称为原发性胆汁性肝硬化）是一种肝内胆管进行性破坏导致胆汁淤积、肝硬化、肝衰竭为特征的自身免疫性肝病。患者多表现为无症状或出现疲乏、胆汁淤积（瘙痒、脂肪泻）或肝硬化（门脉高压、腹水）等症状。实验室检查可发现胆汁淤积，IgM升高，最具意义的是血清中出现抗线粒体抗体。肝组织活检对诊断和分期是必要的。治疗包括熊去氧胆酸，奥贝胆酸，消胆胺（针对瘙痒的）、补充... Common.TooltipReadMore 阳性，而在PSC中阴性。肝胆系统的影像学检查通常从超声开始，以排除肝外胆管梗阻。虽然超声或CT可显示导管扩张，诊断需要胆管造影显示肝内和肝外胆管多发狭窄与扩张。胆道造影应从磁共振胰胆管造影磁共振成像（MRI）（MRCP）开始。内窥镜逆行胰胆管造影内镜逆行胰胆管造影（ERCP）影像学检查对于准确诊断胆道疾病是必需的并且对于识别肝脏局部病变（例如脓肿、肿瘤）具有重要意义，但是它对于识别和诊断弥漫性肝细胞疾病（例如肝炎、肝硬化）作用有限。传统上超声经腹部进行检查，检查前需要禁食一定的时间，它提供了脏器的结构信息而不是功能信息。对于胆道系统，特别是胆囊，超声是最便宜、最安全和最敏感的影像学检查方法。对于下列情况超声是可选择的检查方法：筛查胆道异常... Common.TooltipReadMore (ERCP)通常是第二选择，因为它是有创的。通常明确诊断不需要进行肝活检肝活检提供关于肝脏结构和肝损伤的病理信息（损伤的类型和程度以及是否有纤维化），这不仅仅对于肝病的诊断是必需的，而且对于肝病的分级、判断预后和治疗也是必需的。虽然只能得到小部分组织，但是这块组织通常具有代表性，即使对于局部病变亦然。经皮肝活检常在床旁超声引导下进行。超声引导下进行是首选，因为它能帮助观察肝脏的情况和定位目标局灶病变。一般来说，当怀疑肝脏异常并且用更无创的方法不能明确病因或者需要组织病理学进行分级时有指征进行肝活检（见... Common.TooltipReadMore 肝活检，如果行肝活检，可见胆管增生、管周纤维化、炎症和胆管消失。当疾病进展时，管周纤维化从汇管区向外扩展，最终导致继发性胆汁性肝硬化。患有 PSC 的成年人，即使没有肝硬化，应该接受腹部成像影像学检查影像学检查对于准确诊断胆道疾病是必需的并且对于识别肝脏局部病变（例如脓肿、肿瘤）具有重要意义，但是它对于识别和诊断弥漫性肝细胞疾病（例如肝炎、肝硬化）作用有限。传统上超声经腹部进行检查，检查前需要禁食一定的时间，它提供了脏器的结构信息而不是功能信息。对于胆道系统，特别是胆囊，超声是最便宜、最安全和最敏感的影像学检查方法。对于下列情况超声是可选择的检查方法：筛查胆道异常... Common.TooltipReadMore （超声、腹部计算机断层扫描或磁共振成像/磁共振胰胆管造影）每6至12个月筛查一次胆囊癌和胆管癌胆囊及胆管肿瘤胆囊和胆管肿瘤可引起肝外胆管梗阻。可以无症状，但通常有全身或反映胆管梗阻的症状。诊断基于超声检查加上CT胆管成像或磁共振胆胰管成像。预后通常很差。机械性胆汁引流可减轻胆管梗阻造成的瘙痒、反复败血症和疼痛。（亦见胆管功能概述）胆管癌（cholangiocarcinomas）和其他胆管肿瘤少见（发生率1～2/10万），通常是恶性的。胆管癌主要发生在肝外胆管：60％～70％发生在肝门周围（Klatskin肿瘤），25％发生在远端肝管，其... Common.TooltipReadMore 。应定期监测碳水化合物抗原 (CA) 19-9 的血清水平（1 诊断参考文献原发性硬化性胆管炎（PSC）是胆管节段性的炎症、纤维化和狭窄，病因不明。80％的患者也有炎症性肠病，通常是溃疡性结肠炎。其他伴随的情况有结缔组织疾病、自身免疫性疾病、免疫缺陷综合征，有时合并机会性感染。乏力和瘙痒症状隐匿发生，进行性加重。通过胆管造影术（磁共振胰胆管造影术[MRCP]或内镜逆行胰胆管造影[ERCP]）进行诊断。终末期患者有肝移植指征。（亦见胆管功能概述） PSC是硬化性胆管炎最常见的类型大多数（70％）PSC患者是男... Common.TooltipReadMore )。结肠镜检查筛查试验结直肠癌非常多见。症状包括便血或排便习惯改变。对于适当的人群，建议使用下列几种方法之一进行筛选。结直肠癌通过结肠镜诊断。治疗方法是手术切除，淋巴结受累时联合化疗。美国每年新发结直肠癌 (CRC) 估计为147,950例，死亡估计为53,200例( 1)。 40至50岁左右的发病率急剧上升。超过半数的结直肠癌位于直肠和乙状结肠，95%为腺癌。男性结直肠癌比女性稍多见。5%的患者同时患有结肠癌和直肠癌（一个以上）。... Common.TooltipReadMore 和活组织检查肝活检肝活检提供关于肝脏结构和肝损伤的病理信息（损伤的类型和程度以及是否有纤维化），这不仅仅对于肝病的诊断是必需的，而且对于肝病的分级、判断预后和治疗也是必需的。虽然只能得到小部分组织，但是这块组织通常具有代表性，即使对于局部病变亦然。经皮肝活检常在床旁超声引导下进行。超声引导下进行是首选，因为它能帮助观察肝脏的情况和定位目标局灶病变。一般来说，当怀疑肝脏异常并且用更无创的方法不能明确病因或者需要组织病理学进行分级时有指征进行肝活检（见... Common.TooltipReadMore 应该在无预先存在的炎症性肠病炎症性肠病概述炎症性肠病（IBD），包括克罗恩病和溃疡性结肠炎，表现为反复发作和缓解的不同状态，均以胃肠道不同部位的慢性炎症为特征，这些炎症可引起腹泻和腹痛。炎症由胃肠黏膜中细胞介导免疫反应所致。炎症性肠病的确切病因尚不明，但有证据表明，在有多因素遗传易感性患者肠道中，正常菌群所诱发的异常免疫反应与该病有... Common.TooltipReadMore (IBD) 患者中进行，在诊断 PSC 时进行，并且由于结直肠腺癌的风险增加，应从 PSC 诊断之日起，PSC 和 IBD 患者患者每年进行一次检查。诊断参考文献 1.Bowlus CL, Lim JK, Lindor KD: AGA Clinical practice update on surveillance for hepatobiliary cancers in patients with primary sclerosing cholangitis: Expert review.Clin Gastroenterol Hepatol 17(12):2416-2422, 2019.doi: 10.1016/j.cgh.2019.07.011 原发性硬化性胆管炎的治疗支持治疗内窥镜逆行胰胆管造影 (ERCP) 扩张术治疗主要（显性）狭窄复发性细菌性胆管炎或肝衰竭并发症可行肝移植。无症状患者一般只需要监测（如体格检查和肝功能检查，每年2次）并且，如果是成人，定期成像和测量 CA 19-9 以进行胆囊癌和胆管癌胆囊及胆管肿瘤胆囊和胆管肿瘤可引起肝外胆管梗阻。可以无症状，但通常有全身或反映胆管梗阻的症状。诊断基于超声检查加上CT胆管成像或磁共振胆胰管成像。预后通常很差。机械性胆汁引流可减轻胆管梗阻造成的瘙痒、反复败血症和疼痛。（亦见胆管功能概述）胆管癌（cholangiocarcinomas）和其他胆管肿瘤少见（发生率1～2/10万），通常是恶性的。胆管癌主要发生在肝外胆管：60％～70％发生在肝门周围（Klatskin肿瘤），25％发生在远端肝管，其... Common.TooltipReadMore 筛查。熊去氧胆酸（最高20mg/kg/d）减少瘙痒和改善生化标志物，但不影响存活。慢性胆汁淤积和肝硬化需要支持治疗。细菌性胆管炎需要用抗生素和治疗性 ERCP 内镜逆行胰胆管造影（ERCP）影像学检查对于准确诊断胆道疾病是必需的并且对于识别肝脏局部病变（例如脓肿、肿瘤）具有重要意义，但是它对于识别和诊断弥漫性肝细胞疾病（例如肝炎、肝硬化）作用有限。传统上超声经腹部进行检查，检查前需要禁食一定的时间，它提供了脏器的结构信息而不是功能信息。对于胆道系统，特别是胆囊，超声是最便宜、最安全和最敏感的影像学检查方法。对于下列情况超声是可选择的检查方法：筛查胆道异常... Common.TooltipReadMore (1 治疗参考文献原发性硬化性胆管炎（PSC）是胆管节段性的炎症、纤维化和狭窄，病因不明。80％的患者也有炎症性肠病，通常是溃疡性结肠炎。其他伴随的情况有结缔组织疾病、自身免疫性疾病、免疫缺陷综合征，有时合并机会性感染。乏力和瘙痒症状隐匿发生，进行性加重。通过胆管造影术（磁共振胰胆管造影术[MRCP]或内镜逆行胰胆管造影[ERCP]）进行诊断。终末期患者有肝移植指征。（亦见胆管功能概述） PSC是硬化性胆管炎最常见的类型大多数（70％）PSC患者是男... Common.TooltipReadMore )。如果一个单一狭窄是阻塞的主要原因（高达45%的患者可能出现显性狭窄）(2 治疗参考文献原发性硬化性胆管炎（PSC）是胆管节段性的炎症、纤维化和狭窄，病因不明。80％的患者也有炎症性肠病，通常是溃疡性结肠炎。其他伴随的情况有结缔组织疾病、自身免疫性疾病、免疫缺陷综合征，有时合并机会性感染。乏力和瘙痒症状隐匿发生，进行性加重。通过胆管造影术（磁共振胰胆管造影术[MRCP]或内镜逆行胰胆管造影[ERCP]）进行诊断。终末期患者有肝移植指征。（亦见胆管功能概述） PSC是硬化性胆管炎最常见的类型大多数（70％）PSC患者是男... Common.TooltipReadMore )，ERCP扩张（细胞学刷检和原位荧光杂交[FISH]筛查胆管癌）和支架植入可缓解症状。对于原发性硬化性胆管炎患者，肝移植肝移植肝移植是第二常见的实体器官移植。（参阅移植概述）肝移植的适应证包括：肝硬化（占美国肝移植的70％;其中10％到20％是由丙型肝炎引起的）暴发性坏死性肝炎（约8%）肝细胞肝癌（约7%） Common.TooltipReadMore 是唯一能够改善预期寿命的治疗方法，可以治愈。复发性细菌性胆管炎或终末期肝病的并发症，（如难治性腹水腹水腹水是指腹腔内游离的液体。最常见的原因是门静脉高压。症状通常是由腹腔膨胀所致。通过体格检查、超声或CT可以诊断。治疗包括限钠饮食、利尿和治疗性穿刺。腹水可以出现感染（自发性细菌性腹膜炎），通常伴有疼痛和发热。感染的诊断依靠腹水的分析和培养，需用抗生素治疗。慢性肝病可以引起腹水，有时急性肝病也可以引起。与肝脏无关的情况也能引起腹水。肝脏原因引起腹水包括下列情况：门静脉高压（>... Common.TooltipReadMore 、门体分流脑病门-体分流性脑病门-体分流性脑病是一种神经精神综合征，可能会在肝病患者身上发生。它大多数发生于存在门－体分流的患者进食高蛋白或急性代谢应激（如消化道出血、感染、电解质紊乱）时。症状主要为神经精神症状（如意识错乱、扑翼样震颤、昏迷）。诊断依靠临床表现。治疗通常是纠正急性病因、口服乳果糖和不可吸收的抗生素，如利福昔明。（也可以参见肝脏结构和功能和肝脏疾病患者的评估.) 门-体分流性脑病比肝性脑病或肝昏迷更好地描述了病理生理过程，但三者可以替换... Common.TooltipReadMore 或食管静脉曲张静脉曲张静脉曲张指远端食管或近端胃的静脉扩张，通常由肝硬化导致的门静脉系统压力增高所致。可引起严重出血而没有其他症状。诊断需行胃镜。治疗主要为内镜下套扎和静注奥曲肽。有时需行经颈静脉肝内门体分流术（TIPS）。（另请参阅消化道出血概述以及美国肝病研究协会肝硬化门脉高压出血：风险分层、诊断和管理：2016年实践指南。) 门脉高压由多种原因引起，主要是肝硬化。如果门脉压力长时间高于下腔静脉，会形成静脉侧支。最危险的静脉侧支形成于食管远端和... Common.TooltipReadMore 破裂出血），或胆管癌（在适当选择的患者中），都是肝移植的指征。治疗参考文献 1.Aabakken L, Karlsen TH, Albert J, et al: Role of endoscopy in primary sclerosing cholangitis: European Society of Gastrointestinal Endoscopy (ESGE) and European Association for the Study of the Liver (EASL) Clinical Guideline.Endoscopy 49(6):588-608, 2017.doi: 10.1055/s-0043-107029 2.Bowlus CL, Arrivé L, Bergquist A, et al: AASLD practice guidance on primary sclerosing cholangitis and cholangiocarcinoma.Hepatology 77(2):659-702, 2023. doi: 10.1002/hep.32771 关键点大多数 (80%) PSC 患者患有 IBD，通常是溃疡性结肠炎，并且许多患者具有自身抗体。如果患者，特别是炎性肠病患者，肝功能检查中有原因不明胆汁淤积型异常，则应该怀疑PSC。超声排除肝外胆道梗阻，然后做MRCP（或ERCP，作为第二选择）。通过定期肝检查监测患者，定期筛查胆囊癌和胆管癌，并治疗症状和并发症（例如，ERCP 评估和治疗显性狭窄）。出现复发性细菌性胆管炎或肝衰竭并发症可行肝移植

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什么是PSC电机 | 艾斯湃纳

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2020年9月14日

PSC电机是Permanent Split Capacitor Motor的缩写，译为"电容感应电机"或"永久分相式电容电机"，是一种AC电机。

AC电机按照其使用的电源分类，可以分为使用三相交流电*1的三相感应电机和使用单相交流电*2的单相感应电机。单相感应电机包括几种类型，其中之一是使用电容*3产生磁场，并产生近似的两相电流而启动电机旋转的类型*4。根据利用电容启动这一情况，也可以将其称为"电容电机"或"电容启动式电机"等。另外，有的类型不仅用于启动，还在运转过程中使用电容保持旋转，称为"电容运转电机"或"永久电容式电机"。

三相交流电：从发电站传输过来并在工厂等中使用的交流电。

单相交流电：供给普通家庭使用的交流电。

电容：用于储电和放电的电子元件。也称为电容器。另外，单相感应电机还包括不使用电容的罩极线圈式电机。

单相感应电机中除了使用电容启动的"电容启动式"以外，还包括"分相启动式"和"罩极线圈启动式"。

电容电机的机制

为了使用配送给家庭等的单相交流电让电机转动起来，需要具备用以启动旋转的机制。为此，电容电机采取了如图所示的结构，在电容电机中装入主绕组和次级绕组，主绕组直接连接电源，次级绕组经电容连接电源。

电机接通电源后，电流先流过主绕组，然后由于需要流过电容，因此会稍稍延迟后再流过次级绕组。这样在主绕组与次级绕组之间电流就产生了相位（波形的时移），并按照主绕组→次级绕组→主绕组→次级绕组→主绕组……的顺序产生磁场，电机由此获得旋转力。

电容电机发明和普及背景

公认的单相感应电机（电容电机）原理之一是弗朗索瓦·阿拉戈在1824年发现的"阿拉戈圆盘"。这是沿着非磁性材料制成（铜板或铝板等不与磁铁反应的金属）的圆盘旋转磁铁时，圆盘会跟随磁铁旋转的现象。

19世纪末，以提出交流电系统而闻名的尼古拉·特斯拉发明了具有实用性的感应电机，正是由于这个技术的产生，AC（交流）电机进入了工业领域。之后，出现了更易于操作、简单便宜而便于小型化的单相感应电机，由此被广泛用于普通家庭和中小型工厂等中的家用电器类和各种设备的动力源。

然而，到了今天，比单相感应电机更高效、更易操作的EC电机已经得到普及，所以EC电机被用于多个领域。另外，EC电机是Electronically Commutated Motor的缩写，通常称为无刷DC（BLDC）电机。

电容电机与EC电机的比较

虽然电容电机是一种实用且易于使用的电机，但是EC电机在此之上具有能效更高、更容易控制转速等的优点，因此现在被广泛应用于各个领域。两者的优点/缺点比较如下。

电容电机

EC电机

结构

结构简单

需要控制模块所以结构复杂

速度/力矩

难以控制

易于控制并且可以灵活调节速度/力矩，操作性能优越

可靠性

长时间使用会影响电容的寿命，因此维护较为费时

没有电刷，因此无需维护即可长时间使用

效率

电容发热会损失部分能量，因此效率较低

不仅高效，而且可以使用控制器进行控制以降低高峰时段的功耗

响应速度

难以调节速度，响应速度慢

对转速控制的响应速度快

噪音/振动

大

小

成本

低

高

电容电机与EC电机的用途

电容电机由于可以使用身边常见的单相交流电流，因此广泛用于家庭、小规模的工业和农业等领域，但最近EC电机的使用在日益增加。

EC电机用于下列用途。

空调设备

住宅设备

热水器、燃烧器单元

环境设备

浴室周边产品

自动售货机

冷冻、冷藏展示柜

金融终端（ATM）、找零机、货币兑换机、售票机

无尘室

光学产品

打印机

复印机

保健设备

商业设备

同一系列的专栏

什么是电动机

什么是步进电机

什么是直流无刷电机

什么是伺服电机

什么是鼓风机

什么是执行器

DC电机是什么？电机特征和原理的介绍

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E-PORTS带你走进船代 | PSC检查为何如此重要？ - 知乎

E-PORTS带你走进船代 | PSC检查为何如此重要？ - 知乎切换模式写文章登录/注册E-PORTS带你走进船代 | PSC检查为何如此重要？E-PORTS已认证账号相信长期从事航运的人一定对PSC检查，也就是港口监督国检查并不陌生，PSC的英文全称为Port State Control，因为PSC检查的流程相当繁琐，且在不同港口国都会有不同的标准侧重点，一旦因为没达到标准，甚至可能导致船舶被滞留，所以这项检查可以说是极其重要的，今天小编就来给大家全面科普一下PSC检查的各类小知识。PSC检查小科普那么究竟何为PSC检查呢，又是为何PSC检查会让各国家港口相关部门以及航行船舶都如此兴师动众呢？简单来说，PSC检查就是港口国对靠港船舶进行一系列的检查，其目的是为了：提升航运安全防止海洋污染保障船员安全确保船舶设备安全PSC检查主要会参考海上六大公约标准：SOLAS(国际海上人命安全公约)、MAPOL（国际防止船舶造成污染公约）、ILLC（国际船舶载重线公约）、STCW（海员值班标准国际公约）、ISPS(国际船舶和港口设施保安公约）、MLC（国际海事劳工公约）。根据六大公约的标准，PSC检查官员会着重检查：救生设备、消防系统和设备、GMDSS无线电设备、船舶及船员相关证书。当发现问题时，官员会给到相应的缺陷代码给到船长，以便船长进行后续整改，常见的代码有12（所有缺陷已纠正）、17（要求船长在离岗前纠正缺陷）、30（滞留船舶）。绝大部门船舶遇到的检查不通过的原因都是因为船舶机械问题，船体构件老化、对港口国要求不了解、日常维修不规范导致的设备安全隐患。这些问题都会导致船舶停滞而影响船期，所以船东方对待PSC检查需要尤为重视，避免造成滞留而产生的损失。PSC检查的由来任何国际公约和法规的由来都是惨痛代价换来的，PSC检查也不例外。1978年3月16日，赖籍油轮Amoco Cadiz在法国Brittany海岸搁浅，造成223000吨原油及4000吨燃油外泄，严重污染海洋环境。污染事故发生之后，1980年12月，法国海洋部长邀请西、北欧13国相关部长研讨，会后由工作组起草PSC备忘录，随着逐步的法规完善，才有了如今完善的PSC检查法则，并形成了八大区域性港口国监督备忘录组织，分别为巴黎备忘录、东京备忘录、拉丁美洲协议、加勒比地区备忘录、地中海备忘录、印度洋备忘录、中西非备忘录、黑海地区备忘录，需要注意的是美国不属于任何一个备忘录组织，而是由其海岸警卫队（USCG）实施独立的港口国监督检查。船代在PSC检查中扮演的角色由于各国港口的PSC检查要求都有所不同，在船舶航行至该港口前需要提前了解目的港口的对应要求并做好准备，尤其是后疫情时代，PSC检查的细则不断的根据疫情情况进行调整，这时船长就需要向目的港口的船代进行咨询，当地的船舶代理可以说对自己所在港口的PSC检查的侧重点较为了解，所以也能给船长专业的意见作为参考。在港口相关部门完成船舶的PSC检测后，会提出一系列的整改意见，其中有些整改条目会影响到船舶的再次出航，而相关部门的检查人员并不会再出动登轮进行复查，这时，船长或者船东会通过船舶代理去相关部门申请复查，并随时与检查人员保持联系，避免影响船舶的船期安排。【E-PORTS温馨提示】船舶在到达目的港之前，一定要重视并按照规定做好船舶的各项检修工作，不断的完善船舶管理体系，不仅可以顺利的通过PSC检查的各项证书，保护海洋的环境，最重要的是能确保船舶安全远洋，保证船员们的生命安全！如果船舶到港前需要了解当地港口PSC的情况可以通过E-PORTS咨询并获取协助！编辑于 2023-06-02 15:32・IP 属地上海船代远洋运输业务（书籍）跨境物流赞同 3添加评论分享喜欢收藏申请

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Home›Life Sciences›Stem Cell Research›Stem Cell Research Learning Center›Stem Cell Research Resource Library›Pluripotent Stem Cell Resource Handbook›PSC Resource Handbook – CulturePSC Resource Handbook – CultureSee Navigation‹Pluripotent Stem Cell Resource HandbookPSC Resource Handbook – Reprogramming

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2.1 Introduction 2.2 Feeder-dependent culture systems 2.3 Feeder-free culture systems 2.4 Choosing a culture system 2.5 Adapting to feeder-free culture systems 2.6 Cryopreservation 2.7 ReferencesRequest a copy of the PSC Resource HandbookIf you’ve found this chapter – Culture – useful, you may be interested in getting your own copy of the entire PSC Resource handbook in either convenient PDF format or print.Request your free copy

2.1 Introduction

Culturing PSCs requires a compatible combination of media, matrices, and passaging methods that support cell health and pluripotency. When human ESCs were first derived by Thomson et al. in 1998 [1], the ESCs were cultured on mitotically inactivated MEF feeder cells with a medium supplemented with fetal bovine serum (FBS). This pioneering work served as the starting point for the development of various PSC culture systems. To reduce the risk of contamination from heterologous proteins and, MEFs in feeder-dependent cultures were replaced with human-derived alternatives, including human fibroblast cells. To further reduce variable components and animal material, FBS was replaced with KnockOut Serum Replacement, a supplement for FBS-free, feeder-dependent culture which now has a research-use version called Gibco KnockOut Serum Replacement – Multi-Species. Eventually, media and matrices were developed to support PSCs completely independent of feeder cells. Coming full circle in 2011, the Thomson lab published a fully defined, feeder-free culture system that supported the undifferentiated growth of PSCs without any animal components; the medium is now available as Essential 8 Medium. A newer version of this medium, Gibco Essential 8 Flex Medium, is also based on the same formulation.Clearly, much of the evolution of PSC culture systems was driven by interest in generating PSCs suitable for clinical applications, devoid of nonhuman animal material (xeno-free or XF), or better yet, free from any animal-origin material, human or otherwise (animal origin–free or AOF).However, the migration from serum-based media towards more defined media has been valuable for both research and translational applications; more defined media make use of known components at known quantities, and hence perform more consistently. However, not all customer applications require XF or AOF media and many of the newer, more advanced, and demanding PSC applications actually benefit from a more complex medium. For example, Gibco StemFlex Medium is richer than Essential 8 Medium and was optimized to support these new and more challenging applications such as single-cell passaging and gene editing.Altogether, a variety of “culture systems” now exist to satisfy the progressively stringent requirements of different PSC applications, from basic research to translational applications, from simple cell culture to gene editing. With a full spectrum of culture systems available, there can be multiple options to satisfy each application’s requirements. Choosing between different options may ultimately depend on other considerations, including cost, workflow, and scalability. This chapter will discuss the features, reagents, and workflows associated with different culture systems. To facilitate the discussion, the culture systems will be divided into feeder-dependent and feeder free systems and will primarily revolve around the different PSC culture media.Go to thermofisher.com/pscculture to find the right PSC media for your research.(Top)

2.2 Feeder-dependent culture systems

Feeder-dependent culture systems generally support pluripotency and cell health using a DMEM-based medium that is supplemented with basic fibroblast growth factor (bFGF), and serum or more commonly, KnockOut Serum Replacement, a more defined and more reliable serum-free alternative that is specifically optimized for PSC culture. As the name implies, feeder-dependent cultures rely on feeder cells to provide many other proteins, most often growth factors and extracellular matrix proteins, that are necessary for PSCs to grow in culture. With the abundance of components to support PSC growth, feeder-dependent culture systems are considered rich and robust and are still widely used years after feeder-free systems have been introduced.The vast majority of feeder-dependent cultures use MEF feeders that have been irradiated or treated with mitomycin-C to arrest the cell cycle. The most commonly used MEFs are derived from the outbred CF1 mouse strain, but MEFs can be derived from a variety of strains, including inbred C57BL/6 mice or even drug-resistant mice, thereby enabling anything from routine culture to drug selection with feeder-dependent PSCs. The preparation and quality control of the feeder cells is critical, as isolation of the fibroblasts can introduce contaminants like mycoplasmas, and incomplete inactivation can allow MEFs to overgrow and outcompete slower-growing PSCs. A broad selection of pre-isolated, pre-inactivated wild type or drug-resistant Gibco MEFs can save the time and trouble of generating feeder cells. The rigorous quality testing helps ensure that they are free of contamination and can truly support PSC culture.To learn more about Gibco MEFs, go to thermofisher.com/gibcomefWorkflowGenerally, the proper maintenance of PSCs involves daily media changes as well as daily inspections to check the culture’s morphology, general health and confluency. Healthy and undifferentiated PSCs cultured on MEFs have a high nucleus-to-cytoplasm ratio and grow in colonies that are compact and have well-defined edges (Figure 2.1), whereas areas of differentiation contain larger, flatter, and less compact cells (Figure 2.2). Some level of differentiation can be expected in cultures when colonies have grown too big or when cultures have become too confluent, particularly when colonies begin to overlap with each other. When this occurs, areas of differentiation can be removed by manual dissection prior to passaging. However, to prevent excessive differentiation, feeder-dependent cultures should be passaged regularly, typically every 3–4 days with a split ratio around 1:4 to 1:6, with actual intervals and ratios adjusted depending on cell line and culture confluency.Figure 2.1. Phase-contrast image of H9 hESCs grown on inactivated MEFs. Cells were grown on gelatin-coated plates using medium containing KnockOut Serum Replacement. The ESC colony consists of compact cells, exhibits a well-defined border, and is surrounded by inactivated MEFs with spindle-like morphology (10x magnification).Figure 2.2. Phase-contrast image of differentiating H9 ESC colony on inactivated MEFs. Cells were grown under the same conditions as in Figure 2.1. Part of the colony remains compact and well-defined, but another part shows flatter, loosely arranged cells, indicative of differentiation (5x magnification).Unlike many other cell types, feeder-dependent PSCs are passaged as cell clumps that are harvested using either enzymatic or mechanical methods. For enzymatic passaging, colonies are incubated with Gibco Collagenase Type IV or Gibco Dispase II until the edges lift from the plate. They are then completely detached and fragmented into smaller clumps by trituration, with care taken to obtain the optimum fragment size; very small and very large fragments tend to differentiate or fail to attach. Mechanical passaging can be more appropriate for certain cases, such as when picking colonies for expansion. This involves scoring colonies into smaller fragments using a 25-gauge needle and lifting the fragments off the plate with a 200 μL pipette tip so that they can be transferred to a fresh plate. Scoring can also be done for bulk passaging, although scoring a whole plate is tedious and time-consuming. If mechanical methods are preferred for bulk passaging, the Gibco StemPro EZPassage Tool can provide a quicker, easier alternative. The StemPro EZPassage Tool is a grooved rolling tool that moves across multiple colonies at a time, generating uniform fragments that can then be scraped off the plate with a cell lifter. Regardless of passaging method, plates are typically coated with 0.1% gelatin or the ready-to-use equivalent, Gibco Attachment Factor, to facilitate feeder cell attachment and spreading. The feeder cells themselves should be seeded at least a day in advance of culture.To access detailed protocols for culturing PSCs on feeder cells, go to thermofisher.com/cultureprotocolsUseful tipsIt is possible to skip changing the media for one day if the cells are double-fed the day before. However, this practice should be limited to minimize the stress on cells and to consequently minimize the risk of accumulating karyotypic abnormalities.For cultures that are exhibiting high levels of differentiation, it can be possible to save the line by manually picking the undifferentiated colonies and transferring them to a fresh plate of MEFs.(Top)

2.3 Feeder-free culture systems

Feeder-free cultures work on the principle of omitting feeder cells and supplementing the remaining culture components to compensate for the nutrients, growth factors, and extracellular matrix proteins that are missing. This is exemplified by the use of MEF-conditioned media to create culture systems that physically do not contain feeders but still contain the soluble factors secreted by feeder cells. However, MEF-conditioned media fail to offer much improvement over using actual feeder cells, and the associated workflow can be even more tedious. As such, studies have parsed the protein contributions of MEFs and investigated the pathways that are critical for pluripotency, with the goal of developing better feeder-free systems. These studies initially led to a first generation of stem cell media that did not require MEFs, neither as feeder cells nor for conditioning media. Next, they led to minimal, defined, xeno-free media like Essential 8 Medium and Essential 8 Flex Medium. Finally, they have resulted in optimized media like StemFlex Medium that support pluripotency and survival despite the stress that PSCs undergo during more demanding applications.

Gibco Essential 8 Medium and Gibco Essential 8 Flex Medium

In order to develop a more defined medium to support the growth and pluripotency of PSCs more consistently, James Thomson’s lab re-examined the composition of an existing feeder-free medium, testing new combinations with fewer components [2]. The result was a fully defined, xeno-free, feeder-free medium that is now available as Essential 8 Medium. While most feeder-free media formulations consist of more than 20 components, adding complexity, time, and cost, Essential 8 Medium is formulated with only eight components. Furthermore, unlike most feeder-free media, Essential 8 Medium was specifically designed to exclude serum albumin, which is a frequent source of variability. This simple formulation has been extensively tested and has been shown to maintain pluripotency and normal karyotype in multiple PSC lines for over 50 passages. An updated formulation, Essential 8 Flex Medium, has been enhanced to eliminate daily feeding schedules required for most PSC culture maintenance. This medium uses the same wild type bFGF found in the original Essential 8 Medium, but a slightly modified formulation extends the activity of this growth factor, along with other key heat-sensitive components found in PSC medium. This allows for a flexible feeding schedule in which feeding can be skipped for up to 3 days in a week, including up to 2 consecutive days, without compromising pluripotency and genetic stability.

Gibco CTS Essential 8 Medium

Based on the widely published Essential 8 Medium, we have developed a cell therapy–grade, fully defined human pluripotent stem cell culture medium. Gibco CTS Essential 8 Medium offers all the same benefits of the RUO version but with fully animal origin–free (AOF) components to support clinical research applications.CTS Essential 8 Medium offers a best-in-class design for clinical PSC applications. Its AOF formulation reduces the risks associated with animal- and human-origin components. It is also cGMP-manufactured in an FDA registered facility for medical devices. Additionally, the CTS Essential 8 Medium offers extensive regulatory documentation and safety testing, and comes with an FDA Drug Master File. This medium is a well-accepted formulation that has been used and referenced extensively in the research market. The CTS Essential 8 Medium enables the translational market to seamlessly move from research to clinical applications.

StemFlex Medium

StemFlex Medium is our newest medium developed to deliver superior performance in the innovative and challenging applications used in today’s stem cell research, such as reprogramming, single-cell passaging, and gene editing. In addition to core performance enhancements, it delivers the convenience of a flexible feeding schedule (including weekend-free options), just like Essential 8 Flex Medium. It also offers the ability to choose between matrix and passaging reagents best suited for a given application.

Workflow

Passaging PSCs cultured under feeder-free conditions is subject to many of the same considerations and practices as cells that are grown on MEFs. Cells are inspected and fed daily, although there is greater flexibility in this schedule when using Essential 8 Flex Medium or StemFlex Medium. As a guideline, healthy and undifferentiated feeder-free cells grow in colonies (Figure 2.3), just like in feeder-dependent cultures. However, the colonies may appear flatter or less compact, and the colony edges may not be as smooth, especially right after passaging. As with feeder-dependent cultures, overconfluency leads to areas of differentiation (Figure 2.4). These don’t typically require manual removal, but it is best to prevent widespread differentiation by passaging regularly, particularly when using passaging methods other than Versene reagent or EDTA. Passaging methods using reagents such as TrypLE Select or Gibco StemPro Accutase Cell Dissociation Reagents do not differentially dissociate PSCs from the plastic surface and thus also harvest differentiated progeny.Figure 2.3. Phase contrast image of hiPSCs grown under feeder-free conditions. Gibco Human Episomal iPSCs were grown on Geltrex matrix–coated plates using Essential 8 Medium (10x magnification).Figure 2.4. Phase contrast image of differentiating hiPSC colony without feeders. Cells were grown under the same conditions as in Figure 2.3. Part of the colony remains compact, but another part shows flatter, loosely arranged cells, indicative of differentiation (5x magnification).

Matrices and passaging methods

Essential 8, Essential 8 Flex and StemFlex Media can be used with a variety of matrices, including Geltrex matrix, Gibco vitronectin, and rhLaminin-521. Geltrex matrix consists of basement membrane proteins derived from Engelbreth-Holm-Swarm mouse tumors. Unlike Geltrex matrix, vitronectin and rhLaminin-521 are defined, as well as xeno-free recombinant human matrix proteins. The vitronectin substrate specifically uses the VTN-N variant of the protein, which supports hPSC attachment and survival better than the wild type variant when used with Essential 8 Medium [2]. On the other hand, Gibco rhLaminin-521 has been proven to promote PSC survival under stressful conditions, even in the absence of small-molecule Rho-associated protein kinase (ROCK) inhibitors [3]. It can be used for routine culture and is particularly useful in stressful applications such as reprogramming, adaptation of PSCs from richer to leaner media, and single-cell clonal outgrowth following fluorescence-assisted cell sorting (FACS).The standard passaging method for cells cultured in Essential 8, Essential 8 Flex, and StemFlex media is nonenzymatic. Colonies are subjected to a short treatment with 0.5 mM EDTA in Gibco calcium-free, magnesium-free DPBS, which is also available in a ready-to-use format as Gibco Versene Solution. Once EDTA has been replaced with the medium, cells are then removed from the plate by gentle pipetting. This results in cell clumps that are transferred to a new plate without further trituration. Cells are passaged when they reach ~85% confluence. This typically occurs at day 3–7 with split ratios of around 1:6 to 1:20.For specific applications like gene editing or clonal expansion or to make the workflow more amenable to large-scale culture, it may be necessary to passage cells as single cells using Gibco TrypLE Express Enzyme or as 2-to 3-cell clusters using StemPro Accutase Cell Dissociation Reagent. The best culture system for supporting such passaging methods would be the combination of the most robust feeder-free medium and matrix—StemFlex Medium and rhLaminin-521. If a Geltrex matrix or VTN-N is preferred with StemFlex Medium, single-cell passaging can still be achieved with the use of Gibco RevitaCell Supplement, a proprietary, chemically defined, xeno-free formulation that contains antioxidants, free radical scavengers, and a ROCK inhibitor with higher specificity than Y-27632 or thiazovivin. In this protocol, adherent PSCs are dissociated using TrypLE Express or Select Enzyme. Gibco RevitaCell Supplement is added to the medium during the first 24 hours after passaging, but is no longer required in subsequent media changes. Note: Do not add additional ROCK inhibitors such as Y-27632 or thiazovivin when using RevitaCell Supplement in the medium.If a defined, xeno-free medium is required, Essential 8 Medium can also support single-cell passaging when used with rhLaminin-521 or when used with RevitaCell Supplement and VTN-N or Geltrex matrix.For a guide to the different matrices and passaging methods for StemFlex and Essential 8 media, refer to Table 2.1.

Large-scale culture

For some applications like the development of cell therapies, it may be necessary to generate large numbers of PSCs, preferably under xeno-free conditions. Published research has shown that this can be achieved using Essential 8 Medium through aggregate cultures or through the use of microcarriers. In the prior study, PSCs were passaged using StemPro Accutase Cell Dissociation Reagent, then cultured in a 100 mL spinner flask with Essential 8 Medium supplemented with ROCK inhibitor during the first 24 hours [4]. Agitation allowed the formation and survival of homogeneous PSC aggregates, enabling the expansion of cultures from 1 x 106 to 1 x 109 cells within 20 days. In the latter study, EDTA-passaged cell clumps were given a day to adhere to vitronectin (VTN-N)-coated polystyrene microcarriers in a static culture with Essential 8 Medium supplemented with ROCK inhibitor [5]. After 24 hours, the medium was replaced with Essential 8 Medium without ROCK inhibitor, and a 50 mL spinner flask was used to stir the culture, first intermittently, then later, continuously. Inoculation of 55,000 cells/cm2 of microcarrier surface area generated a cell yield of 3.5 after 10 days of culture.Table 2.1. Guide to choosing matrices and passaging methods for StemFlex and Essential 8 media. Click image to enlargeUseful tipsIt is very important to prewarm complete Essential 8 Medium at room temperature and not in a 37°C water bath. Basic bFGF activity can decline rapidly with repeated temperature changes from 4–37°C.ROCK inhibitors can be used with Essential 8 Medium; however, this isn’t necessary and they are not routinely used with our clump passaging protocols. If the use of a ROCK inhibitor is desired, it should be added to the medium during the first 24 hours post-passage.Cells should not be pretreated with the RevitaCell Supplement before passaging. Cells only require the RevitaCell Supplement for 18–24 hours after single-cell passaging, with the cells being fed regular unsupplemented medium for the remainder of the culture.RevitaCell Supplement can also be added to growth media during the first 24 hours post-thaw to achieve optimum post-thaw recovery of cryopreserved cells.(Top)

2.4 Choosing a culture system

As previously mentioned, feeder-dependent cultures have a proven track record of supporting PSC growth and maintaining pluripotency, and are sufficient for many basic research projects. The rich and robust medium makes for forgiving culture conditions that are ideal for novice PSC researchers, and even more experienced researchers may use feeder-dependent cultures as backup or as a point of comparison for feeder-free cultures. However, feeder-dependent cultures do carry certain disadvantages that can discourage prospective users. The undefined components are prone to inconsistent performance. Moreover, the workflow is more tedious, involving a longer passaging protocol, requiring significant work to obtain and prepare the feeder cells, often also requiring grooming of cultures to remove areas of spontaneous differentiation. These may be undesirable but tolerable for small-scale work. However, they are extremely difficult to deal with for very large projects.In contrast, feeder-free systems do not require feeder cell isolation, inactivation, banking, and pre-plating; nor do they require feeder cell removal prior to certain downstream experiments such as molecular analysis or flow cytometry. With these workflow improvements and with the added possibility of performing single-cell passaging, feeder-free systems are generally more amenable to large-scale culture and high-throughput experiments. By eliminating the need for feeders, they also perform more consistently. That said, even among feeder-free cultures systems there can be differences in consistency because some media and matrices do contain less-defined components. In addition, some media contain more components than others, and that equates to not only greater cost and greater complexity, but also greater potential for experiencing inconsistencies in performance. Due to these considerations, fully defined and completely xeno-free minimal culture systems such as Essential 8 Medium and Essential 8 Flex Medium can be more favored for workflows spanning basic research to translational research. In basic research, these systems are more attractive because, in addition to reduced cost, they provide a cleaner background for performing experiments on different biological pathways. These media are also produced under good manufacturing practice (GMP); this helps increase consistency and reduce burden for future translational research.While the benefits of a leaner system are abundant, it is important to understand that they also tend to be more sensitive to stressors, and can be less forgiving of harsh cell manipulations. Furthermore, not all customers require a xeno-free system and many of today’s more complex workflows are not well supported by lean media. The convergence of these factors makes a modern, robust medium like StemFlex Medium extremely attractive. Gibco StemFlex Medium addresses the insufficiencies of the other media on the market, which were not designed to support the wide variety of modern PSC workflows and applications that are used today. As with all Gibco PSC media, StemFlex Medium is manufactured under GMP to offer a consistent and robust product for research applications such as gene editing, single-cell passaging, and clonal expansion, to name just a few.There are many subtleties to choosing a PSC culture system, and the final choice depends on the research goal. For example, even if the intended application in basic research can ostensibly be satisfied by feeder-dependent systems, Essential 8 feeder-free systems may still be preferred if the actual experiment requires or can benefit from the scalability, consistency, cleaner background, improved workflow, and the potential to skip media changes over entire weekends (when using Essential 8 Flex Medium). However, if the experiment involves heavy cell manipulation or is executed by someone less experienced in PSC culture, a richer medium like StemFlex Medium or a feeder-dependent option like Gibco DMEM/F-12 with KnockOut Serum Replacement – Multi-Species may offer more benefit. To assist in choosing the appropriate culture system, the advantages and disadvantages of various media are summarized in Table 2.2.For additional assistance on finding the right PSC culture tools, go to thermofisher.com/pscculture

Table 2.2. Comparison of PSC culture methods.

Click image to enlarge(Top)

2.5 Adapting to feeder-free culture systems

Sometimes it is necessary to transition PSCs into a specific feeder-free culture system in order to satisfy changing project requirements or new experimental designs. Several adaptation schemes and protocols enable a smooth transition to the StemFlex and Essential 8 media systems (Figure 2.5). PSCs in other feeder-free media like mTeSR™1 Medium (STEMCELL Technologies) can be passaged with Versene Solution directly into StemFlex Medium or Essential 8 Medium with Geltrex matrix. If culturing in Essential 8 Medium with VTN-N is preferred, cells can be passaged into this system after one to two passages in Essential 8 Medium with Geltrex matrix.Feeder-dependent cultures can be adapted directly into Essential 8 Medium with VTN-N or into StemFlex Medium with Geltrex matrix, but obtaining the right colony fragment size is critical, as large fragments form embryoid bodies while small fragments differentiate upon plating. The recommended approach to obtaining optimum fragment sizes involves harvesting colonies using collagenase IV followed by trituration and, more importantly, two rounds of gravity sedimentation as described in the adaptation protocols. For lines that are difficult to transition or simply to achieve the best results with, cells can be transferred to the medium of choice with rhLaminin-521 for a passage or two before transitioning to Essential 8 Medium with VTN-N or to StemFlex Medium with Geltrex matrix. The combination of Essential 8 Medium and rhLaminin-521 is available as the Gibco Essential 8 Adaptation Kit.

Transition from other feeder-free cultures

Click image to enlarge

Transition from feeder-dependent cultures

Click image to enlargeFigure 2.5. Guide for adaptation into StemFlex and Essential 8 media systems. The left side shows the scheme for transitioning PSCs from other feeder-free systems. The right side shows the scheme for adapting from other feeder-dependent cultures.(Top)

2.6 Cryopreservation

Cryopreservation is an important part of every cell culture workflow. In the PSC workflow, cells are cryopreserved to store back-up cultures that can be recovered in case the cells currently in culture are compromised by genetic changes, contamination, excessive cell death, or spontaneous differentiation. They are also frozen to save cell lines for future use, including when projects are temporarily placed on hold or when creating stem cell banks. Finally, PSCs are cryopreserved to enable the transport and sharing of PSC cultures between different facilities. In summary, cryopreservation enhances continuity, longevity, and flexibility of projects, and it improves the availability and dissemination of different PSC lines.The traditional method for cryopreservation involves freezing PSCs in 10% DMSO, typically by resuspending the cell pellet in PSC medium at half the desired volume, then bringing it up to the full volume with a 2X freezing medium containing 20% DMSO. To minimize the exposure to DMSO, the cryovial is promptly transferred to –80°C in a controlled-rate freezing apparatus that then decreases the temperature gradually by approximately 1°C/min. After 24 hours, the cryovial is transferred for long-term storage to a liquid nitrogen freezer at –200°C to –125°C. When the PSCs need to be thawed, the cryovial is warmed in a water bath until a small sliver of ice remains. Again, to minimize exposure to DMSO and to improve cell survival, the contents are quickly transferred to a conical tube and diluted by adding fresh medium. To avoid osmotic shock, the medium is added dropwise while gently shaking the conical tube. After washing and resuspending in fresh culture medium, the cells are then transferred to a plate and allowed to recover and grow. Cryopreservation and thawing are stressful for cells, but substituting or supplementing the traditional reagents with the optimized Gibco PSC Cryopreservation Kit allows for maximum post-thaw viability and recovery of cryopreserved PSCs. The PSC Cryopreservation Kit comprises a ready-to-use, defined, xeno-free cryopreservation medium and the AOF RevitaCell Supplement, which improves cell survival through antioxidants, free radical scavengers, and a more specific ROCK inhibitor. For clinical applications or simply for a ready-to-use alternative that has been designed for use with a wider variety of cells, one may also use Gibco Synth-a-Freeze Cryopreservation Medium. This defined medium contains 10% DMSO in a HEPES and sodium bicarbonate buffer, without antibiotics, antimycotics, hormones, growth factors, serum, or protein.To assist you in choosing the best cryopreservation medium, these options are compared in Table 2.3. For more information, go to thermofisher.com/cryopreservation Table 2.3. Summary of key characteristics and performance of PSC cryopreservation media. Useful tipsFor optimum results, collect cells from a healthy, actively growing, high-confluency culture.Ensure that differentiated colonies have been removed so that only high-quality PSCs are cryopreserved.PSCs may require several passages to recover after cryopreservation. Do not be discouraged if cultures look unhealthy immediately after thawing.(Top)

2.7 References

Thomson JA, Itskovitz-Eldor J, Shapiro SS et al. (1998). Embryonic stem cell lines derived from human blastocysts. Science 282(5391): 1145–1147.Chen G, Gulbranson DR, Hou Z et al. (2011). Chemically defined conditions for human iPSC derivation and culture. Nat Methods 8(5):424–429.Rodin S, Antonsson L, Hovatta O, Tryggvason K (2014) Monolayer culturing and cloning of human pluripotent stem cells on Laminin-521-based matrices under xeno-free and chemically defined conditions. Nat Protoc. 9(10):2354-2368Wang Y, Chou BK, Dowey S et al. (2013). Scalable expansion of human induced pluripotent stem cells in the defined xeno-free E8 medium under adherent and suspension culture conditions. Stem Cell Res 11(3):1103–1116.Badenes SM, Fernandes TG, Cordeiro CSM, Boucher S, Kuninger D, Vemuri MC et al. (2016) Defined Essential 8 Medium and Vitronectin Efficiently Support Scalable Xeno-Free Expansion of Human Induced Pluripotent Stem Cells in Stirred Microcarrier Culture Systems. PLoS ONE 11(3): e0151264.(Top)For Research Use Only. Not for use in diagnostic procedures.

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tp最新版安卓|psc

tp最新版安卓|psc

国家普通话水平测试在线报名系统

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