提供了本研究从生物力学的美国和国际社会的资助。

参与者 六单方面，小腿截肢患者（男5例，女1例，年龄= 46±16岁，质量= 104.7±9.7公斤，身高= 1.75±0.08 M）参加了这项研究。五六个不得不截肢者因因先天性骨病创伤与其他截肢。所有的截肢者使用的假肢接受腔界面的锁形悬式悬挂系统和动态弹性响应假肢脚（3学院公园，2 Flex的脚，1创世记二）。参加者招募集中在谁是完全卧床，用了一个下肢假肢的至少一年截肢，并保持一定程度的体力活动无论是在他们的职业或日常活动。该方案经大学的机构审查委员会和知情同意从每个参与者在参与之前获得的。 地上行走试验 <p类="jove_content"&gt;每个参与者的首选步行速度被确定为参与者使用一个舒适的速度仿佛走在他们的车到店门口沿着20μm的人行道走去。光电管为基础的计时系统被用来量化遍历大约在人行道的中间5个m段所需的时间。首选步行速度进行了量化为五项试验的平均值。每名参加者则完成了五成功地上行走试验，同时收集地面反作用力从两个测力板（480赫兹）和运动（60赫兹）从六摄像机运动分析系统的数据。成功的试验是那些内的参与者的首选速度±3％，并有调整步幅接触力平台，没有明显的迹象。逆反射标志被放置在双侧股骨大转子，股骨外侧髁，外踝，足跟外侧方面，第五跖骨之前哒头TA集合。 一个三段（大腿，小腿和脚），矢状面逆动力学模型来估算得到的关节力和力矩在髋关节，膝关节和踝关节。根据从德列娃8回归方程估计分部惯性属性完好无损的身体部分。假体和残肢的惯性性质直接测量和假体柄部和足部（参见步骤由以下步骤协议）之间分配。单因子变异数分析重复测量来确定假体转动惯量的估计，无论是直接的措施或使用完整段的估计，在立场和挥杆过程中产生的峰值合资的力和力矩的影响。鉴于合成联合反作用力和力矩型材是所有参与者之间类似的，算法是写在MATLAB（MathWorks公司，马萨诸塞Natic​​k）专注于步态周期内的特定的窗口来识别每个单独的峰quantit的IES（参见％步态周期表2）。一个邦费罗尼调整的置信区间的基础上因变量的数目被做了。显着的差异被认为是在p &lt;0.05。 振荡与反应板系统的说明 用于测量假体的惯性特性的振动系统包括由80/20的铝，内铝笼是可调整的，和一个红外光电池（ 见图1A）的外保持架或支承结构。的内笼从外笼与穿过两个低摩擦压配轴承的轴暂停。以适应不同尺寸的假体的内笼可以缩短或约15厘米（或6英寸）加长。此外，内壳还具有用于确保轿厢内的假体的牢固的配合两个可调节板。 A板带紧定螺钉是用d，来确保该内壳的振动具有低于5℃的幅度，以便估计可以基于简谐运动方程。光电管直接连接到一个柜台上的数据采集卡的计算机作为笼中通过光电的前记录每一个TTL脉冲。一个LabVIEW虚拟仪器（VI）的程序是用来收集和处理的TTL脉冲。振荡系统（ 图1A）的内笼被用作反应板的系统（ 图2）中带刻度与范围高达10公斤，灵敏度，精确到克和2刀刃用于支撑内笼组合在反应板的测量。该技术用于量化一个膝下假体的惯性特性包括三个主要步骤:1）振荡反应及董事会协议，2），用于估计假体转动惯量的数学方程，以及3）分发假体转动惯量为足部和小腿赛格<html>目。 <img alt="图1" src="/files/ftp_upload/50977/50977fig1highres.jpg" /> 用于测量振荡周期振荡机架图1 A）图片。请注意，有一个外部支撑结构，保持固定的内壳，其中，所述假体是固定的，来回振荡中用于定时。 乙光电池的前部）的摆动轴线的特写视图也示出了螺钉用于设置振荡振幅小于5°C）的特写镜头的光电池和内笼的远端的视图来说明调节端板。注意，为了减少我们使用薄铝和去除任何多余的铝，而不会牺牲该结构的强度的内笼的重量。 ighres.jpg"/&gt; 从说明用于估计质量体系的中心反应板设置的振荡系统的外部支撑结构拆除可调铝框（ 即 ，内笼）图2。反应板的原理图。需要注意的是两轴（又名，刀刃）用于支撑内笼; 1在保持器与其他（近端）的左端（前端）的边缘定位在刻度的顶部。这两个支承轴之间的距离表示在反应板的长度。摆动轴是走出来的页面。 1，惯性测量协议<ol><li>最初，有椅子，其中假腿可以舒适地抬离阀座，使得人可以执行一系列膝盖弯曲和伸展的动作为旋转膝关节中心（COR）的被确定的被截肢者静坐。 </li><li>一旦膝盖COR标识（它可能有助于把一个小馅饼磁带在​​西科CE），有被截肢者的立场和措施如下。 <ol><li>从假体膝关节COR的顶部（唇）测量的距离;如果膝盖COR坐在劣于假体的这个值应该被记录为负值的唇部。 </li><li>测量膝关节COR和COR脚踝之间的距离。脚踝COR被假定为在类似的位置，该完好脚踝。 </li></ol></li><li>与假体和底层套筒取出，取残肢的几个测量使用柔性卷尺。使用这些测量基于模拟残肢作为一个直立圆锥6,21的圆台，并假设1.1统一组织密度，g∙厘米-3月13日估计残肢的惯性特性。 <ol><li>测量残余肢体的近端周。此周长应测量尽可能靠近膝关节的最大周长（&lt;EM&gt;例如，通常从膝关节约两指宽）。 </li><li>测量残肢的远端周围。此周长应在残肢上的前端，最后骨突出来测量。 </li><li>测量残肢从腓骨头到残肢的最前端方面的距离的长度。 </li></ol></li><li>通过消除轴从振荡架取下内笼。把被截肢者的衬垫和被截肢者目前假体的插座内使用任何帘布层。然后安全地与鞋仍然在内部振荡笼（ 图1）内放置假体。在这个系统中，两个可调板水平滑动并且当拧入固定位置的保持架内假体的顶部。对于假体的脚用Velcro紧固带将其固定在笼子的前端板。 </li><li>振荡机架内重新定位内笼。 SECU再车轴并确保内笼的悬浮臂对准的固定螺丝，将设置振荡的角小于5°。 </li><li>收集3振荡试验，定位在所述内壳的假体。振荡的周期将表示了完成一个完整的振荡用在其自身重量的内笼摆动并只受重力影响的时间。要开始振荡试验拉动内笼后面，直到它击中的固定螺丝，然后将它向前推，直到固定螺丝和内壳之间的空间是可见的。记录的平均时间为振荡为每个审判完整的周期。 </li><li>前转移到反应板上测量，测量和使用数字测径器或柔性卷尺仍然固定在机架上的假体记录的内笼的尺寸如下。这些措施会在内部笼子配置更改后，在步骤1.9去除假体，并使用还期间的系统的惯性特性的估计。这些测量是比较容易采取与水平放置的内笼和休息上的反应板测试的刀刃。 <ol><li>测量最佳可调板与固定横向构件在其内笼的顶部之间的距离。 </li><li>测量底部可调板与固定横向构件在内部保持器的顶部之间的距离。 </li><li>测量底部可调板与固定横向构件在内部保持器的底部之间的距离。 </li><li>测量反应板的长度;这是反应板的测试期间，将用作载体的2刀边缘的位置之间的距离。 </li></ol></li><li>放置在反应板设置在机架和假肢。确保规模在这一点上的读数为零。放置在刻度的内笼的一端，并在第i的底部定位在刀口新新人类创新笼，使得没有两个刀刃和内笼是水平之间产生张力。抬起规模档次几次，并把它背下来的规模。一旦一个一致的读数从规模上实现时，记录此值。 </li><li>从内笼取出假体。如果顶部和/或底部板必须被移动到取出假体，返回所述板用在步骤1.7中测得的尺寸其原来的位置。一旦笼尺寸是什么，他们是用假体在笼子里，重复步骤1.8，记录反应板读数只是笼。 </li><li>从假肢取下鞋和测量鞋的质量，其次是假体的质量，而不鞋。 </li><li>就拿假体的多次测量。 <ol><li>测量COR之间踝和脚的足底表面的距离。 </li><li>测量假肢脚的长度没有鞋。 </li><li>将鞋背在prosthesis和测量从脚踝COR到鞋的鞋底的距离和脚与鞋的长度。 </li></ol></li><li>振荡机架内重新定位的内笼确保黑角落与反射带是最接近光电管。固定轴，并确定了内壳的所述悬浮臂对准的固定螺丝，将设置振荡的角度小于5°。收集10个振荡试验，其中这段时间每次试验中只有第一个振荡周期将被记录。注:请参阅附录A解释为什么我们只使用第一个振荡周期时，内壳是由本身不振荡的假体。 </li></ol> 2，用于估算假体惯性数学方程<ol><li>调整身体质量占估计使用下列公式完好段惯性特性的前假体的降低的质量: <img fo:content-width="2in" sRC ="/ files/ftp_upload/50977/50977eq1.jpg"/&gt;（1） 其中ABM是调整后的体重，肉骨粉是测量的体重而戴假体，M 优点是假体的质量M 残差是残肢（解剖结构下仍然存在截肢后膝关节）的质量，并C（0.057男性; 0.061为女性）是ABM的百分比由完整柄和脚8入账。 </li><li>估计的完整腿的基础上，ABM假腿和大腿的大腿，小腿和脚，并且它们各自的段长度8的惯性属性。 </li><li>质量位置的假体中心首先被表示为相对于基准轴（ 图2）: CM pros_ax =（Lrxn *（R 利弊+框架 - R的帧 ））/ M 的优点 （2） 其中Lrxn代表的支持点之间的距离，R 利弊+帧代表的刻度读数<html>用于假体和铝框架一起，R表示帧的刻度读数为唯一的帧，而m 正反表示假体的质量。 </li><li>根据振荡和参考轴（Losc_ref）之间的距离，该假体的质量位置的中心被表示为相对于振荡轴线: CM pros_osc = Losc_ref - CM pros_ax（3） 这是需要的假体的相对的转动惯量，以该振荡轴线的后续计算。 </li><li>最后，质量位置的中心被表示为相对于基于所述振荡轴线和顶部可调节的端板（d_plate）之间的距离的假肢接受腔的近端: CM pros_prox = CM pros_osc - d_plate（4） </li><li>计算惯性矩为每个条件（单独笼和笼+假体）: 977eq5.jpg"/&gt;（5） 其中I是轴的转动惯量相对于所述振荡轴线的力矩，τ为1振荡的平均周期，m是该系统的质量，g是重力加速度，d为摆动轴线之间的距离的中心的系统的质量。的相对于所述振荡轴线的假体的转动惯量之间的I 轴为单独的笼子和I 轴为笼加假体被计算为差值。平行轴定理，然后用于表达关于通过膝关节的横向轴线的假体的转动惯量。 </li><li>结合残肢和假体的惯性特性，以确定组合质量，中心相对质量状况到膝盖，并使用平行轴定理表达的惯性通过大规模的位置的联合中心系统绕一横向轴线的力矩。 </li></ol> 3。分布假体转动惯量为足部和小腿段要分发的假体和残肢的惯性特性成足（只假肢脚）和柄部（假肢接受腔，主塔和残肢）的逆动力学建模段惯性特性是基于从拆除假体数据来确定。被拆除的假肢的总质量为2.126公斤，与1.406千克插座质量（包括塔质量）和0.72千克的脚质量。因此，66％的总假体质量被分摊到假肢接受腔，34％被分配到脚。进行了敏感性分析，以确定什么样的影响这对大约膝关节假体的转动惯量的估计时刻。这种分析是基于六个从以下马特斯等人的膝关节假体的惯性特性的实验测量。21（数据通过与作者个人通信获得）。当利弊正题小腿和足部群众根据德列娃8测定（英尺= 24％;柄=总假体的质量的76％），约膝关节假体的总转动惯量相比较的实际低估了约5％的估计使用振荡技术实验值。使用基于对脚的拆卸假体（34％）和柄部（66％）质量百分比，转动惯量有关的膝关节总的矩相比，实验测量被高估了约2％。 <ol><li>分发假肢足部之间的假体的质量（34％）和插座（66％）的基础上拆除假肢的测量段。 </li><li>假肢脚的COM位置根据回归方程为一个完整的8脚确定。这一步是基于灵敏度分析的结果由米勒25和Czerniecki 等 24。米勒25估计因而造成关节力矩在连护膝护肘E使用:的假体的惯性特性的）直接测量，以及b）使用由回归方程估计为一个完整的小腿和脚假体的惯性特性。对于两种不同的方法，并为两个科目的膝盖瞬间型材之间的平均差额约为3 N·m以下。在这个幅度平均差异为的立场在高峰时刻膝盖不超过2％。 Czerniecki 等 24多个拆除膝下假肢和在刀刃均衡的假肢脚，以确定其COM的位置。当他们比较这些结果的基础上回归方程为一个完整的脚估计，他们发现，有两个估计之间的差别不大。 </li><li>绕一横向轴线的假肢脚的MOI虽然其COM被使用去列娃的8回归为一个完整的脚和估计的脚块从第1步确定。脚的MOI也表示相对于膝关节加兹登克平行轴定理。 <img fo:content-width="2in" src="/files/ftp_upload/50977/50977eq6.jpg" /> （6） <img fo:content-width="3in" src="/files/ftp_upload/50977/50977eq7.jpg" /> （7） </li><li> （;不包括残肢惯性特性CMpros_limb），一个反应板的技术，和假体的分配COM位置获得的假肢接受腔（CMpros_sock）的COM的位置被结合在COM位置的整个假体的估计值来确定相对于膝关节（CMpros_ft）脚从步骤3.2。该CMpros_sock受到限制趴在膝盖和脚踝之间的直线，被确定为: <img fo:content-width="3.8in" src="/files/ftp_upload/50977/50977eq8.jpg" /> （8） </li><li>绕一轴线的假肢脚的MOI虽然膝关节从实验测量为大约膝关节（Iknee_limb）整个假肢的MOI减去，以确定唯一的假肢接受腔的MOI关于膝关节（Iknee_sock）。平行轴定理然后应用通过其COM（Icm_sock），以表达对轴的假肢接受腔的教学语言。 <img fo:content-width="2.6in" src="/files/ftp_upload/50977/50977eq9.jpg" /> （9） <img fo:content-width="3.8in" src="/files/ftp_upload/50977/50977eq10.jpg" /> （10） </li><li>残肢（剩余截肢后膝关节下方的解剖结构）的惯性性质结合假体柄，它被用作柄部上的假肢侧的逆动力学模型的惯性特性的惯性属性。 <img fo:content-width="2.8in" src="/files/ftp_upload/50977/50977eq11.jpg" /> （11） <img fo:content-width="4in" src="/files/ftp_upload/50977/50977eq12.jpg" /> （12） <img fo:content-width="2.8in" src="/files/ftp_upload/50977/50977eq13.jpg" /> （13） <img fo:content-width="3.8in" src="/files/ftp_upload/50977/50977eq14.jpg" /> （14） </li&gt; </ol><img alt="文本" fo:content-width="5in" src="/files/ftp_upload/50977/50977body.jpg" width="600" />

<ol>
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振荡反应板技术，提出了估算膝下假肢的惯性特性。这个系统进行了验证，并估算显示已知的几何固体（附录A）的惯性属性时是可靠的。假体肢惯性特性的一组单边，小腿截肢者估计有两种方式:a）通过直接测量采用振荡反应板技术，以及b）使用的完整的四肢创建标准预测方程。由此产生的惯性财产估计为假肢是为两种方法大为不同。在惯性特性这种差异导致关节动力学显著不同的估计在行走，摆动过程中被观察到的差异较大。 虽然在联合动力学显著差异以两种不同的惯性参数估计的立场发生时，这些差异呈S商场考虑到影响时，尺寸的这些差异，并与挥杆过程中观察到的差异比较。在人体运动的大多数研究，立场在这些统计学显著差异可能不会对这项研究结果产生影响。地面反作用力必须在行走的立场相有很大的影响上下肢关节总体矩震级。17-19虽然有在惯性参数两种型号显著差异，这些差异不足以克服的重要性地面反作用力的贡献立场在此刻联合生产。米勒25以前还建议，在跑步的立 ​​场相假肢侧的惯性特性对下肢关节的动力学幅度影响不大。然而，米勒25只改变亲时考虑到了质量和肢体的位置，质量中心的差异sthetic肢体的惯性特性的逆动力学模型。在转动惯量差异不占在模型中，但有人认为，即使转动惯量加倍或减半，这将可能对联合矩的大小影响不大。该Iα长期运动方程中占的整体联合此刻不到3％在任何时间点运行过程中的立场相。从绝对数字来看，观察矩震级最大的变化为我们研究在髋关节瞬间〜步态周期中的平均幅度增加〜2牛顿米的11％。这是大约一半的运行过程中的立场相观察米勒25的幅度增加。我们的研究结果结合与米勒的建议，假体转动惯量的直接措施，包括转动惯量，对渣打在髋关节和膝关节的关节矩震级只有一个小的或微不足道的影响步行或跑步电子商务阶段。 关于行走的摆动阶段，惯性模型的选择确实对下肢关节动力学的幅值一个显著影响。在摇摆，没有大的外力，如站立时地面反作用力。肢体的运动更加依赖于惯性系统和各分部之间的相互作用。这是由大的变化，当两个不同的惯性模型的逆动力学分析中使用的观察关节动能大小反映。使用基于解剖结构完好的回归方程来摆在假肢模型，建议需要比当被使用的假体的实际测量惯性特性更大的肌肉力量。 在本文中，以直接测量一个低于膝关节假体的惯性特性中描述的技术有几个限制。我们描述一个方法第二只取得了对矢状面分析的腿惯性特性测量。改进这个系统包括创建，可以从三个不同的轴被暂停，这样的惯性所有三个主要的瞬间可以被测量内部的笼状结构。此外，该反应板技术可以用于所有三个平面来测量质量的假体中心的三维位置。另一种改进，可以使残肢质量稍微更准确的估计是使用一个容积评估所描述的Czerniecki和同事24，在残肢在水的气缸暂停来估计其体积而均匀的组织密度是用于估算肢体的质量。此外，而不是使用一个假设的百分比来分配假肢接受腔和脚之间的总假体质量，每个假体可以在脚踝未组装的，这样每个组件可以weighed各自独立。我们的技术的另一个限制是它的实验会话期间需要一些额外的时间。在一般情况下，使用我们的技术来直接测量假体的惯性可能将30分钟加至所需的数据收集会话的总时间。 因为膝下假肢与类似设计（ 即锁销和悬浮物和弹性动力响应假脚），发展估算膝下假肢简单的肢体完好的惯性特性百分比的惯性性质明确的建议，我们的小样本是有问题的。然而，我们的研究结果结合惯性估计从其他研究20,21,23膝下假肢和比较这些结果，以惯性估计四肢完好，一些一致的趋势日渐明显。相比于完好肢体，假肢侧的质量一致性较差30-40％时，COM位置是25-35％C输到膝关节和MOI约为穿过膝关节的横向轴线少50-60％。 总之，使用回归方程为一个完整的小腿和脚来模拟一个低于膝关节假体的惯性特性将影响关节的动力学估计的幅度摆动时，但将有姿态时对这些大小只有很小或影响极小。因此，研究人员只专注于使用完整的肢体惯性属性假肢端模型运动的立场相不太可能改变的研究结论。然而，对于那些有兴趣在摆动期动力学，应考虑假体的惯性特性的直接措施，避免误传的假腿摆动的真正动力。 附录A 可靠性惯性质量的估算和中心矩度与效度为了评估的可靠性和validit我们的实验中的惯性质量和位置的假体中心矩测量Y，两个简单的实验。在第一个实验中，转动惯量和4的物体的质量位置的中心矩进行了实验，估计在三个独立的试验。这四个目标分别为:1）9×9×61厘米处理的木材（质量= 2.8千克），2）9×9×64厘米未经处理的木材块（质量= 2.5千克），3）7×9×65的块未处理的木材（质量= 1.8千克），和4）61厘米长的PVC管和与内直径为8厘米，并为9厘米（质量= 0.8千克）的外径为厘米的块。振荡法12是用于估计惯性关于通过其重心的横向轴线的每个对象的时刻。当一个对象的振荡绕一固定轴的对象，振荡（τ）的周期是成正比的惯性关于固定轴线在对象的时刻。如果振幅小于5°相对中立位置时，的物体的转动惯量可以基于单摆运动估计: <img alt="公式A1" fo:content-width="0.7in" src="/files/ftp_upload/50977/50977eqA1.jpg" /> （A.1） 其中I是轴的转动惯量相对于所述振荡轴线的力矩，m是该系统的质量，g是重力加速度，d为摆动轴线和质量的系统的中心之间的距离。 将反应板技术被用来估计质量位置的各对象的中心。静态平衡假设（Σ 矩 = 0）和由物体的重量产生的力矩，重量，框架，和反作用力的总和，绕一固定的参考轴线。转动惯量和每个对象的位置，质量中心的那一刻也估计基于简单的几何方程。我们的实验措施进行了比较，这些几何estimations到评估的有效性。使用两个（一个用于COM的估计，一个用于内政部估计），我们估计质量位置和转动惯量中心的可靠性进行了评估，单因素一般线性模型方差分析，与3重复测量反映了三次试验。组内相关系数（国际商会）也计算来确定我们估计的可重复性。 在第二个实验中，我们评估了周期振荡（τ）的测量的可靠性。 τ的测定连续10个试验只用铝制框架悬挂在摆动轴和连续10个试验用木块（质量= 2.8千克，尺寸= 9×9×61厘米）固定在铝框和两个悬挂在摆动轴。在每个试验中，τ后，用一个光电管，其输出电压变化的基础上，反射光的强度10个连续的振荡。我们的测量τ的可靠性是一个ssessed采用四，单因子一般线性模型方差分析，进行10次重复测量。两个（一个用于帧只试验和一个用于框架+块试验）方差分析被用来确定连续振荡（ 即数据矩阵设置，使该因素是振荡的一个给定的试验中连续的句点）之间是否τ不同。然后将数据矩阵被旋转90°，以使因子是连续的试验中及两个以上方差分析用于测定τ是否跨越连续的试验有所不同。组内相关系数（国际商会）也被计算，以确定我们的测量的可重复性。 实验1的结果 - 四个物体惯性有关通过其质心（I_obj_cm）横轴每个对象的时刻是一贯高估（通过为木块〜5％和〜为PVC管材12％）相比，基于每个objectR的估计17，S的质量和几何形状（IZ）（ 表3）。我们估计，然而，是非常可靠的。有在惯性的平均此刻没有差异（F 2,6 = 0.154，P = 0.861），用于在三个试验中的四个对象。此外，国际商会透露，整个试验我们的惯性估计的时刻是高度可重复的（ICC = 1.00）。因此，虽然我们的估计倾向于高估的惯性对象的时刻相比，几何估计我们的估计是可靠的。 我们使用一个反应板的技术质量位置估计的中心是基于假设均匀的密度和几何模型的估计是一致的。差异小于1％。有一个在质量位置的平均中心无差异（F 2,6 = 1.126，P = 0.384），用于在三个试验中的四个对象。此外，国际商会透露，整个试验我们的质量评估中心是高度可重复的（ICC&gt; 0.99）。因此，我们的质量估计的中心是有效的和可靠的。 <img alt="表3" fo:content-width="6in" src="/files/ftp_upload/50977/50977table3.jpg" width="600" /> 。表3我们的实验的惯性和四个物体质量的地点中心矩估计相比，基于质量和每个对象的几何估计 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/50977/50977table3.jpg" target="_blank">点击这里获取该表的放大图。</a>变量定义:mframe =质量铝框; mobject =物体的质量; t_frame =只有框架的振荡周期;振荡的周期被确定为10个连续振荡的平均值和连续跨越三个试验。 T_OBJECT =帧周期的振荡和对象在一起;确定相同t_frame; I_Frame_osc =相对于所述振荡轴线的帧的I;I_Frame_obj_osc =帧加上物体相对于所述振荡轴线的予; I_obj_osc =对象相对于摆动轴的我; I_obj_cm =我对通过大规模的对象的中心轴的对象; IZ =理论我预测有关使用下列几何预测方程对象的CM: PVC: <img height="41" src="/files/ftp_upload/50977/table3eq1.jpg" width="208" /> ;其中，R为外半径，r分别为内半径，而h是长 木材: <img height="41" src="/files/ftp_upload/50977/table3eq2.jpg" width="160" /> ;其中a是长度，b是宽度几何CM位置进行预测的对象的长度的50％。 实验2的结果 - 振荡周期（τ）评估当单独的铝框从摆动轴悬挂和摆动，τ持续，系统地降低（F 9,81 = 123.25，P &lt;0.001），较前10个振荡办法第十四通过在所有10振荡试验约6毫秒（ 图5，左图）。在整个试验中，振动的平均周期也发现显著差异（F 9,81 = 13.97，P &lt;0.001）时，只有框架是振荡。然而，国际商会透露，一个给定的试验中在τ超过前10振荡系统减少重复（ICC = 0.99）。当帧和木块（M =2797克）被一起摆动，τ没有超过前10振荡变化（F 9,81 = 3.031，P = 0.116），平均τ跨连续10个试验没有显著差异（ F 9,81 = 3.533，P = 0.093）（ 图5;右图）。国际商会为框架加上对象的试验表明，在给定的试验τ是不可重复的振荡振荡（ICC = 0.17）。这些数据表明，对于帧只试验τ是更好的平均值在一系列三的第一振荡的估计<html> ALS和当一个对象拥有与膝下假体的特点是振荡，τ是更好的估计为跨连续振荡的平均值和在多个试验。 <img alt="图5" src="/files/ftp_upload/50977/50977fig5highres.jpg" /> 图5。周期振荡测量（A）铝框只及（B）框及木制块（block质量= 2.8千克，块尺寸= 9×9×61厘米）组成，每个面板显示10与第10个单独的试验每次试验的振荡显示。仅用帧悬挂在振荡轴线（左图），τ系统降低在第一10振荡。然而，当一个木块加入到该帧时，τ没有系统地跨过第一振荡10（右图）而有所不同。 转动惯量的敏感性振荡周期T"&gt;因为从实验1的结果表明我们的惯性对象的时刻估计一贯高估和实验2的结果表明，在第一个10振荡，我们进行了敏感性分析，以确定量化的最佳方法框架τ减小，τ为框架只顾风雨帧加上对象的试验（ 表4）τ是成正比的对象的转动惯量: <img alt="方程A2" fo:content-width="0.7in" src="/files/ftp_upload/50977/50977eqA2.jpg" /> （A.2） 其中I是轴的转动惯量相对于所述振荡轴线的力矩，m是该系统的质量，g是重力加速度，d为摆动轴线和质量的系统的中心之间的距离。因此，如果τ减小，则确实如此I 轴 ，因为M，G，和d是一个给定的试验中的常数。由于我们估算交配的目的的惯性矩为: 我OBJ =我OBJ +框架 -如果RAME（A.3） 低估的帧 （I帧）的转动惯量会产生惯性估计为对象的较大力矩（我OBJ），这与我们在实验1的估计是一致的。从图 1实验6显示τ为唯一框架试验和帧加上试验对象为对象最轻和最重的对象。这个数字说明，对于较重的物体（ 例如 ，下面的膝关节假体）没有明显的下降τ在第一个10振荡，但对于较轻的对象有一个在τ轻微的系统性下降。 <img alt="表4" fo:content-width="6in" src="/files/ftp_upload/50977/50977table4.jpg" width="600" /> 比较表4。四种不同的方法用于确定振荡的周期。在此分析中所用的目的是处理过的木材的9×9×61厘米的块。条件C产生的惯性对象的时刻的最佳估计数相比，基于对象的质量和几何形状的替代理论估计。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/50977/50977table4.jpg" target="_blank">点击这里获取该表的放大图。</a>注:变量的定义是相同的，如表3条件 。 答:t_frame和T_OBJECT被计算为连续10振荡，在3个试验振荡的平均周期条件B:t_frame和T_OBJECT被计算为振荡跨越3个独立的试验第一阶段的平均条件C:。t_frame被确定为在条件B; T_OBJECT被确定为A条件条件D:t_frame被确定为条件A; T_OBJECT被确定为条件B. <img alt="图6" fo:content-width="6in" src="/files/ftp_upload/50977/50977fig6highres.jpg" width="600" /> 图6。振荡的最重和最轻的对象期间。左侧面板显示前10个周期的三个试验的振荡只对帧和右面板显示相同的帧附加对象的试验。在实验2中，有超过当只有框架摆动的第10振荡τ系统性下降。当重物被振荡（M =2.797公斤），没有在τ没有系统性的下降。然而，在τ略有下降，观察当灯光对象（M =0.716公斤）的振荡。典型低于膝盖假体的质量已报道的范围从1.2到2.1公斤20,21。因此，即使是重量最轻的假肢，τ不应该在展出的前10个振荡大幅下降。 结论当单独的铝框振荡，振荡的周期将被确定为从10振荡试验的第一振荡的平均值。当铝框和假体都是振荡，振荡的周期将被确定为30振荡（3项试验，每次试验在10个连续振荡）的平均值。

要运动过程中量化产生的关节力和力矩，用经验数据时需要关注的系统的逆动力学模型。下肢生物力学，逆动力学模型通常代表了脚，小腿，大腿和作为刚体。输入这些模型有三个主要来源:1）运动运动，二）地面反作用力，以及c）段人体测量学和惯性特性。运动数据收集与各种运动分析系统的，但所有的系统本质上提供的移动（位置，速度和加速度）的基本运动学。地面反作用力收集与力板，并提供作用于脚的接触力。人体测量学是从身体使用标尺，柔性带，和/或卡尺直接进行的测量。这些人体测量被用来估计在逆DYNAMI使用的主体段的惯性属性CS分析。惯性特性包括相对于一个轴段通过段COM或近端或远端接头的质量，质心（COM）的位置和转动惯量（MOI）。用于收集运动和地面反作用力的数据的方法和设备是其中研究组相似，但体节的惯性估计可以有很大的不同研究人员之间，这取决于方法的研究人员选择用于估计这些惯性特性。 可用于估计一个完整无缺的人体部分的惯性特性的各种技术包括:1）根据尸体的数据1-5，2）数学模型（ 即几何模型）6,7，和3）扫描及成像技术的回归方程8-15。许多这些技术需要从身体的直接测量，但它已被证明，无论该估计方法被使用时，主体段的精度基于这些方法换货惯性估计高16。还已经表明，完整的主体段的惯性特性的估计中的误差有在行走17,18上的得到的关节力矩的幅值的影响微乎其微。关节力矩是由地面反作用力，压力的位置，力矩臂长度，以及段运动学17-19的中心影响到更大的程度。因此，毫不奇怪，估计体节的惯性属性的方法有很大的不同横跨文学利用健全的个体时，作为研究参与者给予这些估计小错误都可能对本研究的结果影响不大。 许多这些惯性估计为一个完整无缺的主体部分的通常用于估算为下肢截肢者的假肢的惯性属性。现代下肢假肢使用轻质材料制成resulti纳克在假肢是比它们所取代的四肢轻得多。这将导致在假肢和完好肢体之间的惯性不对称。具有典型的完整柄和脚，以低于膝关节假体的质量和残肢相比是少约35％，并具有质量中心更靠近膝关节20-23约35％。较低的质量和假肢的更近侧的质量分布也产生低得多的（〜60％）的时刻相对惯性到膝关节的假肢相比，在完好的柄和脚。尽管研究人员24,25先前曾建议使用完整的惯性概算假肢对关节的动力学估计的影响不大，这些比较中的行走步态站立期，在地面反作用力占主导地位的产生的力矩集中于得到的关节力矩关节。在摇摆，在地面反作用力是不存在，假体的减少惯性特性更可能影响得到关节力矩的估计。鉴于一些研究，例如 ，26-32利用完好段惯性特性来表示假体的惯性特性和其他直接，例如 21-23估计假体的惯性特性，要理解的选择用于估计假体的惯性特性的方法的影响是很重要的。最大限度地减少所需的测量假体的惯性特性的时间是一个重要的考虑因素在我们的技术的发展。在这里介绍的方法假体依然完好无损所有测量，以减少测量时间，并避免与测量后重新调整假体相关的任何额外时间。 因此，本研究的目的是双重的:1）表明，可直接用于估计AB的惯性特性的一种技术elow - 膝关节假体，和2）对比所提出的技术中走在单侧，小腿截肢者使用联合动力估计完好肢体惯性特性和效应。据推测，联合动力幅度较大时，完整的胫和脚的惯性物业用作比较的假体的惯性特性直接测量的惯性估计假体。

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr height="105">
			<td height="105" style="height:105px;width:216px;">Oscillation Rack &#38; Reaction Board</td>
			<td style="width:144px;">Custom Built</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Outer cage made from 80/20 aluminum, inner cage from various thicknesses of solid of aluminum.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Laboratory scale</td>
			<td style="width:144px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">NI LabView</td>
			<td style="width:144px;">National Instruments</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Software for recording TTL pulses from infrared photocell.</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">BNC-1050</td>
			<td style="width:144px;">National Instruments</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">BNC Breakout box with direct pin connections to the data acquisition card</td>
		</tr>
		<tr height="105">
			<td height="105" style="height:105px;width:216px;">MATLAB</td>
			<td style="width:144px;">Mathworks Inc.</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Software for processing oscillation and reaction board data to predict inertial properties of prosthesis.</td>
		</tr>
	</tbody>
</table>

oscillation and reaction board techniques for estimating inertial properties of a below-knee prosthesis

本研究的目的是双重的:1）证明可用于直接估计一个低于膝关节假体的惯性特性的技术，和2）对比所提出的技术使用完好肢体惯性属性和效应在行走过程中单方面的，小腿截肢者关节的动力学估计。振荡反应板系统进行了验证，并显示测量已知的几何固体的惯性属性时是可靠的。当假体的惯性特性的直接测量中使用了下肢逆动力学建模与基于一个完整的小腿和脚惯性的估计相比，在髋关节和膝关节动力学中行走的摆动阶段均显著降低。姿态时的差异在关节动力学，但是，均较挥杆过程中观察到的小。因此，研究人员专注于行走的摆动阶段应考虑prosthes的影响是对研究成果的惯性财产估计。对于姿态，任一研究中我们研究这两个惯性模型可能会导致类似的结果与逆动力学评估。

假腿远端向膝盖的惯性特性均较完整腿（ 表1）的下部。跨越参与者平均，假肢侧肿块少39％，通过膝盖的转动惯量大约横轴是少52％，质量和位置的中心是接近膝盖24％，而完整腿值进行比较。 <table border="1" cellpadding="0" cellspacing="0" fo:keep-together.within-page="always" width="553"><tbody><tr><td>主题</td><td>完整*质量（kg） </td><td>优点†质量（kg） </td><td> EST。质量差（公斤） </td><td> ‡Iknee 完好 （千克·米2） </td><td> Iknee 利弊 （千克·米2） </td><td>下面的膝关节完好CM（M） </td><td>下面的膝关节优点CM（M） </td></tr><tr><td>一</td><td> 6.03 </td><td> 4.27 </td><td> 1.76 </td><td> 0.604 </td><td> 0.325 </td><td> 0.268 </td><td> 0.215 </td></tr><tr><td>乙</td><td> 6.07 </td><td> 3.39 </td><td> 2.68 </td><td> 0.400 </td><td> 0.196 </td><td> 0.215 </td><td> 0.177 </td></tr><tr><td> Ç </td><td> 5.80 </td><td> 3.12 </td><td> 2.68 </td><td> 0.575 </td><td> 0.194 </td><td> 0.264 </td><td> 0.198 </td></tr><tr><td> ð </td><td> 5.72 </td><td> 3.17 </td><td> 2.55 </td><td> 0.559 </td><td> 0.317 </td><td> 0.265 </td><td> 0.191 </td></tr><tr><td> Ë </td><td> 7.14 </td><td> 4.65 </td><td> 2.49 </td><td> 0.742 </td><td> 0.325 </td><td> 0.276 </td><td> 0.200 </td></tr><tr><td> F </td><td> 6.23 </td><td> 4.22 </td><td> 2.01 </td><td> 0.585 </td><td> 0.287 </td><td> 0.260 </td><td> 0.192 </td></tr><tr><td>平均值±性病</td><td> 6.17±0.51 </td><td> 3.80±0.66 </td><td> 2.36±0.38 </td><td> 0.578±0.109 </td><td> 0.274±0.063 </td><td> 0.258＆＃177; 0.022 </td><td> 0.196±0.013 </td></tr></tbody></table> *完整是指值组合的完整胫和脚。 †优点是指值的组合的假体和残肢。 惯性大约过膝盖的横向轴线‡时刻。 表1比较从膝盖向下的假体和完整的四肢之间的惯性特性。 由此产生合力（ 图3）和力矩（ 图4）在踝关节，膝关节，髋关节和受到影响，在逆动力学模型中使用的惯性参数。具体来说，是摆萌生（〜65％的步态周期）和摆动终止（〜95％的步态周期）期间，当被用在逆动力学评估假体转动惯量的直接测量与基于完整解剖（回归相比，减少关节的动力学<sTRONG&gt;表2）。影响的大小建议挥杆过程中这些差异不平凡的（≥1.0）。此外，联合动力值摆动起始和终止期间平均增加80％时，使用了完整的惯性估计与假体的惯性特性直接措施比较。因此，当一个完好肢体的惯性特性被用于假肢侧进行建模，挥杆过程中假体的侧关节动力学特征更像那些完好肢体的（ 见图3和4）。在步态站立，观察到了一些统计学的差异。观察到髋anterioposterior产生合力（ES = 0.86）的影响最大尺寸的立场在任何区别。虽然这个效果尺寸较大，仍然被视为立场的一部分，终端的立场（〜52％）过程中发生的这一措施的峰值，或肢体被转换成摆动。影响大小为所有其他significa姿态期间观察到的核苷酸差异范围从0.01到0.41，这将被认为是具有这些值中的髋关节产生的反作用力被观察的放大小的影响。虽然立场期间发现显著的差异，当差异（ 即影响的大小）的大小方面认为这些差异可能会导致人们质疑这些差异的意义。 <img alt="图3" fo:content-width="5in" src="/files/ftp_upload/50977/50977fig3highres.jpg" width="500" /> 图3。踝关节，膝关节，并在anterioposterior（左图）和垂直方向（右面板）髋关节合力的反作用力。数据跨学科供呈现的平均值。步态站立期开始在步态周期与脚接触的0％和结束处的步态周期与脚趾离地约60％。秋千继续，直到t的下一个脚接触他的腿一样在步态周期的100％。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/50977/50977fig3highres.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图4" fo:content-width="5in" src="/files/ftp_upload/50977/50977fig4highres.jpg" width="500" /> 图4。有关通过踝关节，膝关节，髋关节和横向轴线（又名，内外侧轴）交易后关节力矩。数据跨学科的演示取平均值。步态站立期开始在步态周期与脚接触的0％和结束处的步态周期与脚趾离地约60％。摆动一直持续到同一腿在步态周期的100％的下一个脚接触。 <img alt="表2" fo:content-width="6in" src="/files/ftp_upload/50977/50977table2.jpg" width="600" /> 表2。峰值得到的联合反应力和力矩跨学科和两个惯性模型之间的统计比较平均到假肢侧的关节动力学注:平均数据以均数（标准差）。 ％步态周期列代表跨学科的平均百分比为发生该变量所在的峰值。P &lt;0.05认为显著。

Watch this Scientific Journal Video about Oscillation and Reaction Board Techniques for Estimating Inertial Properties of a Below-knee Prosthesis at JoVE.com

Oscillation and Reaction Board Techniques for Estimating Inertial Properties of a Below-knee Prosthesis

所需要的逆动力学建模体节段性惯性特性。使用振荡和反应板技术中，膝下假肢惯性特性进行了测定。在假腿的逆动力学模型中使用的假体转动惯量的直接措施导致产生关节的力和力矩的降低幅度。

对于膝下义肢的估算惯性振荡性质与反应板技术

The purpose of this study was two-fold: 1) demonstrate a technique that can be used to directly estimate the inertial properties of a below-knee ...

oscillation-reaction-board-techniques-for-estimating-inertial

Nanyang Technological University

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JoVE Journal

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Bioengineering

Physics

Mechanical Engineering

Unit 1

Moment of Inertia

Oscillations

SCIENTISTS IN ACTION

16.6K 次观看.  University of Northern Colorado. 所需要的逆动力学建模体节段性惯性特性。使用振荡和反应板技术中，膝下假肢惯性特性进行了测定。在假腿的逆动力学模型中使用的假体转动惯量的直接措施导致产生关节的力和力矩的降低幅度。 

视频: Oscillation and Reaction Board Techniques for Estimating Inertial Properties of a Below-knee Prosthesis

Measuring the Mechanical Properties of Living Cells Using Atomic Force Microscopy

Mechanical properties of cells and extracellular matrix (ECM) play important roles in many biological processes including stem cell differentiation, tumor formation, and wound healing. Changes in stiffness of cells and ECM are often signs of changes in cell physiology or diseases in tissues. Hence, cell stiffness is an index to evaluate the status of cell cultures. Among the multitude of methods applied to measure the stiffness of cells and tissues, micro-indentation using an Atomic Force Microscope (AFM) provides a way to reliably measure the stiffness of living cells. This method has been widely applied to characterize the micro-scale stiffness for a variety of materials ranging from metal surfaces to soft biological tissues and cells. The basic principle of this method is to indent a cell with an AFM tip of selected geometry and measure the applied force from the bending of the AFM cantilever. Fitting the force-indentation curve to the Hertz model for the corresponding tip geometry can give quantitative measurements of material stiffness. This paper demonstrates the procedure to characterize the stiffness of living cells using AFM. Key steps including the process of AFM calibration, force-curve acquisition, and data analysis using a MATLAB routine are demonstrated. Limitations of this method are also discussed.

This paper demonstrates a protocol to characterize the mechanical properties of living cells by means of microindentation using an Atomic Force Microscope (AFM).

使用原子力显微镜测量活细胞的力学性能

Mechanical  properties of cells and extracellular matrix (ECM) play important roles in many  biological processes including stem cell differentiation, ...

科研

生物工程

Engineering Platform and Experimental Protocol for Design and Evaluation of a Neurally-controlled Powered Transfemoral Prosthesis

To enable intuitive operation of powered artificial legs, an interface between user and prosthesis that can recognize the user's movement intent is desired. A novel neural-machine interface (NMI) based on neuromuscular-mechanical fusion developed in our previous study has demonstrated a great potential to accurately identify the intended movement of transfemoral amputees. However, this interface has not yet been integrated with a powered prosthetic leg for true neural control. This study aimed to report (1) a flexible platform to implement and optimize neural control of powered lower limb prosthesis and (2) an experimental setup and protocol to evaluate neural prosthesis control on patients with lower limb amputations. First a platform based on a PC and a visual programming environment were developed to implement the prosthesis control algorithms, including NMI training algorithm, NMI online testing algorithm, and intrinsic control algorithm. To demonstrate the function of this platform, in this study the NMI based on neuromuscular-mechanical fusion was hierarchically integrated with intrinsic control of a prototypical transfemoral prosthesis. One patient with a unilateral transfemoral amputation was recruited to evaluate our implemented neural controller when performing activities, such as standing, level-ground walking, ramp ascent, and ramp descent continuously in the laboratory. A novel experimental setup and protocol were developed in order to test the new prosthesis control safely and efficiently. The presented proof-of-concept platform and experimental setup and protocol could aid the future development and application of neurally-controlled powered artificial legs.

Neural-machine interfaces (NMI) have been developed to identify the user's locomotion mode. These NMIs are potentially useful for neural control of powered artificial legs, but have not been fully demonstrated. This paper presented (1) our designed engineering platform for easy implementation and development of neural control for powered lower limb prostheses and (2) an experimental setup and protocol in a laboratory environment to evaluate neurally-controlled artificial legs on patients with lower limb amputations safely and efficiently.

工程平台和设计一个Neurally控制供电采用经假体与评价实验方案

To enable intuitive operation of powered artificial legs, an interface between user and prosthesis that can recognize the user's movement intent is ...

Harmonic Nanoparticles for Regenerative Research

In this visualized experiment, protocol details are provided for in vitro labeling of human embryonic stem cells (hESC) with second harmonic generation nanoparticles (HNPs). The latter are a new family of probes recently introduced for labeling biological samples for multi-photon imaging. HNPs are capable of doubling the frequency of excitation light by the nonlinear optical process of second harmonic generation with no restriction on the excitation wavelength.
Multi-photon based methodologies for hESC differentiation into cardiac clusters (maintained as long term air-liquid cultures) are presented in detail. In particular, evidence on how to maximize the intense second harmonic (SH) emission of isolated HNPs during 3D monitoring of beating cardiac tissue in 3D is shown. The analysis of the resulting images to retrieve 3D displacement patterns is also detailed.

Protocol details are provided for in vitro labeling human embryonic stem cells with second harmonic generating nanoparticles. Methodologies for hESC investigation by multi-photon microscopy and their differentiation into cardiac clusters are also presented.

纳米谐波再生研究

In this visualized experiment, protocol details are provided for in vitro labeling of human embryonic stem cells (hESC) with second harmonic generation ...

In Situ Mapping of the Mechanical Properties of Biofilms by Particle-tracking Microrheology

Bacterial cells are able to form surface-attached biofilm communities known as biofilms by encasing themselves in extracellular polymeric substances (EPS). The EPS serves as a physical and protective scaffold that houses the bacterial cells and consists of a variety of materials that includes proteins, exopolysaccharides and DNA. The composition of the EPS may change, which remodels the mechanic properties of the biofilm to further develop or support alternative biofilm structures, such as streamers, as a response to environmental cues. Despite this, there are little quantitative descriptions on how EPS components contribute to the mechanical properties and function of biofilms. Rheology, the study of the flow of matter, is of particular relevance to biofilms as many biofilms grow in flow conditions and are constantly exposed to shear stress. It also provides measurement and insight on the spreading of the biofilm on a surface. Here, particle-tracking microrheology is used to examine the viscoelasticity and effective crosslinking roles of different matrix components in various parts of the biofilm during development. This approach allows researchers to measure mechanic properties of biofilms at the micro-scale, which might provide useful information for controlling and engineering biofilms.

In Situ Mapping of the Mechanical Properties of Biofilms by Particle-tracking Microrheology

Particle-tracking microrheology investigates the viscoelasticity of materials. Here, the technique is used to determine the viscoelasticity, creep compliance and effective crosslinking roles of different matrix components of a bacterial biofilm. The matrix consists of polymeric substances secreted by the bacteria and its components determine biofilm structure and mechanical properties.

在生物膜的力学性能原位制图粒子追踪Microrheology

Bacterial cells are able to form surface-attached biofilm communities known as biofilms by encasing themselves in extracellular polymeric substances ...

Computed Tomography and Optical Imaging of Osteogenesis-angiogenesis Coupling to Assess Integration of Cranial Bone Autografts and Allografts

A major parameter determining the success of a bone-grafting procedure is vascularization of the area surrounding the graft. We hypothesized that implantation of a bone autograft would induce greater bone regeneration by abundant blood vessel formation. To investigate the effect of the graft on neovascularization at the defect site, we developed a micro&#8211;computed tomography (&#181;CT) approach to characterize newly forming blood vessels, which involves systemic perfusion of the animal with a polymerizing contrast agent. This method enables detailed vascular analysis of an organ in its entirety. Additionally, blood perfusion was assessed using fluorescence imaging (FLI) of a blood-borne fluorescent agent. Bone formation was quantified by FLI using a hydroxyapatite-targeted probe and &#181;CT analysis. Stem cell recruitment was monitored by bioluminescence imaging (BLI) of transgenic mice that express luciferase under the control of the osteocalcin promoter. Here we describe and demonstrate preparation of the allograft, calvarial defect surgery, &#181;CT scanning protocols for the neovascularization study and bone formation analysis (including the in vivo perfusion of contrast agent), and the protocol for data analysis.
The 3D high-resolution analysis of vasculature demonstrated significantly greater angiogenesis in animals with implanted autografts, especially with respect to arteriole formation. Accordingly, blood perfusion was significantly higher in the autograft group by the 7th day after surgery. We observed superior bone mineralization and measured greater bone formation in animals that received autografts. Autograft implantation induced resident stem cell recruitment to the graft-host bone suture, where the cells differentiated into bone-forming cells between the 7th and 10th postoperative day. This finding means that enhanced bone formation may be attributed to the augmented vascular feeding that characterizes autograft implantation. The methods depicted may serve as an optimal tool to study bone regeneration in terms of tightly bounded bone formation and neovascularization.

Implantation of autologous and allogeneic bone grafts constitute accepted approaches to treat major craniofacial bone loss. Yet the effect of graft composition on the interplay among neovascularization, cell differentiation and bone formation is unclear. We present a multimodal imaging protocol aimed to elucidate the angiogenesis-osteogenesis interdependence at the graft proximity.

计算机断层扫描和成骨血管生成耦合光学成像评估头盖骨自体移植和移植物的整合

A major parameter determining the success of a bone-grafting procedure is vascularization of the area surrounding the graft. We hypothesized that ...

Techniques for the Evolution of Robust Pentose-fermenting Yeast for Bioconversion of Lignocellulose to Ethanol

Lignocellulosic biomass is an abundant, renewable feedstock useful for production of fuel-grade ethanol and other bio-products. Pretreatment and enzyme saccharification processes release sugars that can be fermented by yeast. Traditional industrial yeasts do not ferment xylose (comprising up to 40% of plant sugars) and are not able to function in concentrated hydrolyzates. Concentrated hydrolyzates are needed to support economical ethanol recovery, but they are laden with toxic byproducts generated during pretreatment. While detoxification methods can render hydrolyzates fermentable, they are costly and generate waste disposal liabilities. Here, adaptive evolution and isolation techniques are described and demonstrated to yield derivatives of the native Scheffersomyces stipitis strain NRRL Y-7124 that are able to efficiently convert hydrolyzates to economically recoverable ethanol despite adverse culture conditions. Improved individuals are enriched in an evolving population using multiple selection pressures reliant on natural genetic diversity of the S. stipitis population and mutations induced by exposures to two diverse hydrolyzates, ethanol or UV radiation. Final evolution cultures are dilution plated to harvest predominant isolates, while intermediate populations, frozen in glycerol at various stages of evolution, are enriched on selective media using appropriate stress gradients to recover most promising isolates through dilution plating. Isolates are screened on various hydrolyzate types and ranked using a novel procedure involving dimensionless relative performance index (RPI) transformations of the xylose uptake rate and ethanol yield data. Using the RPI statistical parameter, an overall relative performance average is calculated to rank isolates based on multiple factors, including culture conditions (varying in nutrients and inhibitors) and kinetic characteristics. Through application of these techniques, derivatives of the parent strain had the following improved features in enzyme saccharified hydrolyzates at pH 5-6: reduced initial lag phase preceding growth, reduced diauxic lag during glucose-xylose transition, significantly enhanced fermentation rates, improved ethanol tolerance and accumulation to 40 g/L.

Adaptive evolution and isolation techniques are described and demonstrated to yield derivatives of Scheffersomyces stipitis strain NRRL Y-7124 that are able to rapidly consume hexose and pentose mixed sugars in enzyme saccharified undetoxified hydrolyzates and to accumulate over 40 g/L ethanol.

鲁棒戊糖发酵酵母的木质纤维素生物转化的演进技术乙醇

Lignocellulosic biomass is an abundant, renewable feedstock useful for production of fuel-grade ethanol and other bio-products. Pretreatment and enzyme ...

Production of Metal Nanoparticles by Pulsed Laser-ablation in Liquids: A Tool for Studying the Antibacterial Properties of Nanoparticles

The emergence of multidrug-resistant bacteria is a global clinical concern leading some to speculate about our return to a "pre-antibiotics" era of medicine. In addition to efforts to identify novel small-molecule antimicrobial drugs, there has been great interest in the use of metal nanoparticles as coatings for medical devices, wound dressings, and consumer packaging, due to their antimicrobial properties. The wide variety of methods available for nanoparticle synthesis results in a broad spectrum of chemical and physical properties which can affect antibacterial efficacy. This manuscript describes the pulsed laser-ablation in liquids (PLAL) method to create nanoparticles. This approach allows for the fine tuning of nanoparticle size, composition, and stability using post-irradiation methods as well as the addition of surfactants or volume excluders. By controlling particle size and composition, a large range of physical and chemical properties of metal nanoparticles can be explored which may contribute to their antimicrobial efficacy thereby opening new avenues for antibacterial development.

The antimicrobial properties of metals such as copper and silver have been recognized for centuries. This protocol describes pulsed laser-ablation in liquids, a method of synthesizing metal nanoparticles that provides the ability to fine tune the properties of these nanoparticles to optimize their antimicrobial effects.

液体中脉冲激光烧蚀制备金属纳米粒子:研究纳米粒子抗菌性能的工具

The emergence of multidrug-resistant bacteria is a global clinical concern leading some to speculate about our return to a "pre-antibiotics" era of ...

Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and thus achieving stable water permeability through membranes over time. Here, we report a facile method to prepare hydrogels based on zwitterions for membrane applications. Freestanding films can be prepared from sulfobetaine methacrylate (SBMA) with a crosslinker of poly(ethylene glycol) diacrylate (PEGDA) via photopolymerization. The hydrogels can also be prepared by impregnation into hydrophobic porous supports to enhance the mechanical strength. These films can be characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to determine the degree of conversion of the (meth)acrylate groups, using goniometers for hydrophilicity and differential scanning calorimetry (DSC) for polymer chain dynamics. We also report protocols to determine the water permeability in dead-end filtration systems and the effect of foulants (bovine serum albumin, BSA) on membrane performance.

This paper reports practical methods to prepare hydrogels in freestanding films and impregnated membranes and to characterize their physical properties, including water transport properties.

水凝胶的合成与防污性能作为膜的净水

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and ...

Semiautomated Longitudinal Microcomputed Tomography-based Quantitative Structural Analysis of a Nude Rat Osteoporosis-related Vertebral Fracture Model

Osteoporosis-related vertebral compression fractures (OVCFs) are a common and clinically unmet need with increasing prevalence as the world population ages. Animal OVCF models are essential to the preclinical development of translational tissue engineering strategies. While a number of models currently exist, this protocol describes an optimized method for inducing multiple highly reproducible vertebral defects in a single nude rat. A novel longitudinal semiautomated microcomputed tomography (&#181;CT)-based quantitative structural analysis of the vertebral defects is also detailed. Briefly, rats were imaged at multiple time points post-op. The day 1 scan was reoriented to a standard position, and a standard volume of interest was defined. Subsequent &#181;CT scans of each rat were automatically registered to the day 1 scan so the same volume of interest was then analyzed to assess for new bone formation. This versatile approach can be adapted to a variety of other models where longitudinal imaging-based analysis could benefit from precise 3D semiautomated alignment. Taken together, this protocol describes a readily quantifiable and easily reproducible system for osteoporosis and bone research. The suggested protocol takes 4 months to induce osteoporosis in nude ovariectomized rats and between 2.7 and 4 h to generate, image, and analyze two vertebral defects, depending on tissue size and equipment.

The goal of this protocol is to generate a nude rat osteoporosis-related vertebral compression fracture model that can be longitudinally evaluated in vivo using a semiautomated microcomputed tomography-based quantitative structural analysis.

半自动纵 Microcomputed Tomography-based 裸鼠骨质疏松症相关椎体骨折模型的定量结构分析

Osteoporosis-related vertebral compression fractures (OVCFs) are a common and clinically unmet need with increasing prevalence as the world population ...

A Millimeter Scale Flexural Testing System for Measuring the Mechanical Properties of Marine Sponge Spicules

Many load bearing biological structures (LBBSs)&#8212;such as feather rachises and spicules&#8212;are small (&#60;1 mm) but not microscopic. Measuring the flexural behavior of these LBBSs is important for understanding the origins of their remarkable mechanical functions.
We describe a protocol for performing three-point bending tests using a custom-built mechanical testing device that can measure forces ranging from 10-5 to 101 N and displacements ranging from 10-7 to 10-2 m. The primary advantage of this mechanical testing device is that the force and displacement capacities can be easily adjusted for different LBBSs. The device&#39;s operating principle is similar to that of an atomic force microscope. Namely, force is applied to the LBBS by a load point that is attached to the end of a cantilever. The load point displacement is measured by a fiber optic displacement sensor and converted into a force using the measured cantilever stiffness. The device&#39;s force range can be adjusted by using cantilevers of different stiffnesses.
The device&#39;s capabilities are demonstrated by performing three-point bending tests on the skeletal elements of the marine sponge Euplectella aspergillum. The skeletal elements&#8212;known as spicules&#8212;are silica fibers that are approximately 50 &#181;m in diameter. We describe the procedures for calibrating the mechanical testing device, mounting the spicules on a three-point bending fixture with a &#8776;1.3 mm span, and performing a bending test. The force applied to the spicule and its deflection at the location of the applied force are measured.

We present a protocol for performing three-point bending tests on sub-millimeter scale fibers using a custom-built mechanical testing device. The device can measure forces ranging from 20 &#181;N up to 10 N and can therefore accommodate a variety of fiber sizes.

测量海洋海绵针力学性能的毫米尺度弯曲试验系统

Many load bearing biological structures (LBBSs)&#8212;such as feather rachises and spicules&#8212;are small (&#60;1 mm) but not microscopic. Measuring the ...