The authors would like to acknowledge the Center for Advanced Vehicular Systems (CAVS) at Mississippi State University for providing testing facilities and Rush Sports Medical of Meridian, Mississippi for their monetary support.

注:所提出的测试方法的协议是指下列NOCSAE文件（可在http://nocsae.org/）:NOCSAE DOC.002-13m13:"标准性能规格新生产的橄榄球头盔"18。 NOCSAE DOC.011-13m14d:"制造商程序指引本公司产品样本选择进行测试，以NOCSAE标准"24。 NOCSAE DOC.087-12m14:"对于足球FACEGUARDS冲击试验性能要求标准方法"25。 NOCSAE DOC.100-96m14:"故障排除指南测试设备和冲击试验"26。 NOCSAE DOC.101-00m14a:"设备的校准规程"27 1.测试装置<ol><li>构建NOCSAE双线下降支架组件作为NOCSAE DOC的第15.1节定义。 001，18， 如图5所示。确认大会所有组件都安装牢固。 </li><li>对准与头型旋转调节所需位置的头型领口和拧紧头型螺纹锁环安装尺寸"大"NOCSAE头型到放置支架组件。 注意:如果头模是新的或修理，参阅NOCSAE DOC的第5节。 100. 26 </li><li>牢固的三轴加速度计附接到位于所述头模的重心的加速度板。放置加速度在加速度计盘排队在与加速度计板中的孔的加速度两个孔的中心。使用内六角螺丝刀插入两个螺丝，直至该加速计牢固地安装在加速度计板以顺时针方向拧紧。 </li><li> 根据制造商的规范配置数据采集系统。 28 <ol><li> CONNEC吨的数据采集组件的电缆。 <ol><li>加速度计电缆连接到三路同轴分离器，那么同轴电缆连接到同轴分离器的每一个输出。 </li><li>每个同轴电缆的自由端从三通同轴分离器到通道1，2的传感器输入端口，和3位于放大器模块的后部连接。 </li><li>从放大器模块（信道1，2和3）上的数据采集系统（信道1，2和3，分别地）的前输入连接的输出端口连接的同轴线缆。 </li><li>在RS-232电缆的分裂端连接到数据采集系统的后部连接器。 </li><li>剩下的RS-232电缆连接到个人计算机（PC）的COM端口1。 </li></ol></li><li>电源的个人电脑（PC）和登录上。 </li><li>下载并安装数据采集系统软件到计算机上。 </li><li>上电数据采集组件:插上每个组件120伏电源插座插入电源，然后翻转放大器拨动开关至"ON"位置。 </li><li>双击位于桌面打开的软件的数据采集程序图标。 </li><li>观察一个提示，询问检查模块状态，请单击"是"。 </li><li>加载测试设置文件。点击"设置"选项卡上，向下滚动到"打开"，然后选择"测试设置"。 <ol><li>浏览电脑目录下，找到并选择标有"NOCSAE1.TSF"测试设置文件。点击"加载"。 </li></ol></li><li>输入该加速度传感器的信息。 <ol><li>单击活动模块通道3黄色传感器输入图标。 </li><li>插入的z轴加速度校准值（毫伏/ G）进入"CAL值"文本框。 </li><li>点击"上一个"按钮。 </li><li>重复步骤1.4.8.1 - 1.4.8.3对于y轴加速度（信道2）和用于第E X轴加速度计（信道1）。 </li><li>点击绿色的"返回"按钮，退出传感器。 </li></ol></li><li>点击绿色的"保存"图标，然后命名测试设置为"NOCSAE-朱庇特"。 </li><li>点击"保存"。 </li></ol></li></ol> 2.准备头盔<ol><li>选择冲击试验头盔模型。用于头盔的认证，用于根据NOCSAE DOC.011测试选择的样品。 24试验按表1和图1和2中所示的样品。 </li><li>选择每个选定的头盔模型对应的faceguards。从NOCSAE标准不同，与基线面甲这样的头盔进行基础安全帽冲击试验。 </li><li>使用飞利浦螺丝刀，牢固地安装正确的面甲，所有面甲特定的硬件来选择测试每个头盔。与此相反的NOCSAE标准测试方法具D，测试附加faceguards所有的头盔。 </li><li> 根据表1，NOCSAE DOC在温度条件头盔。 002 7，以及NOCSAE DOC.087 25 通过暴露于实验室环境或环境室中。在室温下进行初步头盔跌落测试。 <ol><li>测试之前将所选头盔到实验室环境中，72°F±5°F（22℃，±2℃）中，在至少4个小时。 </li><li>如果所有的环境温度的影响已经进行，暴露的头盔的调节温度，根据表1，对于4但不超过24小时的长。 7 注:至少有两个，但没有导致最高记录SI四个以上的撞击位置环境温度下降会在高温下进行测试值。 </li></ol></li></ol> 3.校准<ol><li> 执行校准头型:每头型必须使用三轴加速度计测试之前进行校准，3"校准MEP垫和放置位置/为该特定的校准MEP垫确定的年度NOCSAE校准垫鉴定报告的速度。 <ol><li>牢固地连接3"校准MEP垫用内六角扳手砧。 </li><li>使用年度NOCSAE校准垫鉴定报告，选择一个撞击位置和相应的冲击速度。 </li><li>使用头模旋转器组件和砧座导轨，调整头模和砧座到所需冲击方向（正面，侧面，或者顶部）。参考表1，NOCSAE DOC的附录2。 001，18日和NOCSAE DOC。 100. 26 <ol><li>移除头模旋转体组件上的锥形-LOC螺栓和定向头模调节到对准螺栓孔到所需的位置。插入和安全地发斯登锥度-LOC螺栓。 </li><li>松开头型螺纹锁环和旋转头型鼻翼位置到所需方向。拧紧头型螺纹锁环。 </li><li>松开两个底板砧螺栓，直到达到预期的效果的位置，实现滑动砧。拧紧基地板状砧螺栓并确保所有连接是否紧固。 </li></ol></li><li>附加发布系统下降支架组件。解除降托架组件到释放系统的高度。居中释放系统的下拉滑座组件的连接点然后为电磁释放系统的切换开关拨至"ON"位置。 </li><li>提高车厢掉落装配决心达到预期的冲击速度的具体高度。注意:特定高度可以为每个系统由于摩擦而变化。更多的影响，可能需要进行变化的高度，以确保正确的入速度是一个chieved。 </li><li>准备用于记录的事件数据采集系统（根据制造商的规格28）。 <ol><li>加载测试设置文件。点击"测试"选项卡，然后单击"收集数据"。 </li><li>浏览电脑目录下，找到并选择标有"NOCSAE-JoVE.TSF"测试设置文件。点击"加载"。 </li><li>点击"确定"。 </li><li>键入测试说明"说明"对话框，然后按"Tab"键。 </li><li>提供了5个字符的测试ID，输入"JoVE1"，然后点击"继续"。 </li><li>点击"继续"。 </li><li>观察仪表升温。一旦计数器达到15秒，单击"继续"。 </li><li>观察自动执行加速度校准该系统。一旦所有的箱子为绿色，单击"继续"。 </li></ol></li><li>使用发布制度，跌落马车assembly和触发数据采集系统通过同时翻转位于释放系统电源控制箱既拨动开关来记录事件。 </li><li>计算并记录所得的SI值。确保结果是1200 SI±2％。 </li><li>重复步骤3.4.2-3.4.8直到结果为三个所需撞击位置而获得的。 注:校准垫应每年在由NOCSAE指定的实验室进行重新确认。 </li></ol></li><li>执行系统检查和维护的结果。 （见18，NOCSAE DOC.001 18） </li></ol> 4.测试过程<ol><li>执行系统检查和维护的结果。 </li><li>交换用于校准的MEP测试焊盘的MEP垫。 </li><li>选择冲击位置和根据表1的测试速度。 注意:影响必须从最低降速度至最高进行。环境温度影响，建议立即进行删除D是以前条件的影响进行。 </li><li>适当调整头模方向和砧座的位置，以达到预期的冲击的位置，如在图1和2，并根据在第3步骤中描绘。 </li><li>选择测试头盔。 </li><li>根据头盔制造商安装说明和NOCSAE程序选择正确头盔适合头型。调整和牢固地安装在头盔南极的头型。 注意:由于该面甲的附加约束，滑石粉的光应用可以在头盔的头模的嵌合帮助。 </li><li>附加的机械释放系统下降支架组件。 </li><li>提高车厢掉落装配决心达到预期的冲击速度的具体高度。 </li><li>准备的数据采集系统，用于记录一个事件。重复步骤3.4.1至3.4.8。 </li><li>使用机械释放系统跌落CARRI年龄组件和同时触发数据采集系统以记录该事件。 </li><li>撞击后，立即记录SI，HIC和峰值加速度的结果。 </li><li>比较记录的结果通过/失败的标准。从NOCSAE标准不同，设置了一通/所有5.46，4.88失败700 SI的价值，4.23米/秒的影响。保持合格/不合格300 SI的标准对所有3.46米/秒的影响。 </li><li>重复步骤4.3-4.11，直到结果为所有需要的影响获得的。 注:这是可以接受的改变头型的方向和位置，砧之前测试一个给定的冲击位置所有的头盔。 </li><li>执行测试完成后系统检查和维护的效果。 </li><li>数据验证:比较检测前和后测系统的检查和确保任何变化是7％或更少。 </li></ol><img alt="图1" src="/files/ftp_upload/53929/53929table1.jpg" /> 表格1:橄榄球头盔跌落试验矩阵表示由滴落速度（米/秒）和冲击位置所需的影响。 （表从NOCSAE DOC修改。002-13m13） <a href="https://www.jove.com/files/ftp_upload/53929/53929table1large.jpg" target="_blank">点击此处查看该图的放大版本。</a>

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The authors have nothing to disclose.

报告的方法，夫妻NOCSAE橄榄球头盔面甲并跌落冲击试验提供了一个独特的技术来评估现代足球头盔更好的性能。评价现代足球头盔这更好的性能特点，最关键的步骤如下:1）正确设置机械试验装置; 2）准确地进行校准程序; 3）正确连接头盔/面甲的头型。 这种方法需要适当的测试设置和校准程序。有由于制造过程中的限制，其中包括在聚合材料的孔隙率每NOCSAE头模之间固有可?...

动机 这个修改后的落塔试验方法的主要目标是要更紧密地代表美国橄榄球头盔系统对场的影响，促进提高安全标准。该entailed试验方法可以提供头盔，有效地开发脑震荡预防头饰增强系统需要应对的知识。脑震荡的发生一贯困扰接触的运动，比如美式足球。仅在美国，与体育有关的脑震荡被估计将要发生，每年1.6至3.8万次。 1橄榄球运动员可以有超过1500个每个赛季头的影响。 2，3虽然大多数影响的程度可能是次震荡，这些影响是由于被称为慢性创伤性脑病（CTE）的冲击引起的神经变性疾病的积累可能导致长期的脑损伤。 4CTE被链接到tau蛋白在大脑中积聚，导致记忆丧失，行为和人格改变，帕金森氏综合征，和语音和步态异常已有时会导致自杀。 5橄榄球头盔已经在过去15年中取得了一定的技术进步，但即使是当今最先进的头盔并不能完全缓解所有的事件力量在头盔上，因此，运动员仍然招致脑震荡。通过BARTSCH 等人进行的一项研究。 6表明，在许多情况下，头部撞击剂量和在穿着老式Leatherhead的头盔是可比的那些穿着广泛使用的21 世纪的头盔，示出了用于在设计和测试标准橄榄球头盔的改进的需要头部受伤的风险。特别是，NOCSAE认证7不需要面甲要包括在该头盔的跌落试验。从t附加的刚度他面甲连接到头盔将极大地改变整个机械响应。本研究需要一种方法，以提供更强大的头盔安全标准，将作为驱动力来促进安全头盔设计。 背景 颅脑损伤指标 有关脑震荡的确切生物学机制仍然不明。虽然很多工作已经在试图通过各种损伤指标来量化颅脑损伤容限已经完成，意见分歧已经出现在关于这些标准的生物医学界。这些损伤的机制都应该涉及到一些实体:直线加速，旋转加速度，冲击持续时间和冲动。 8，9，10，11的几个损伤标准已经用于定义一个震荡线性加速度的量度。韦恩州立公差曲线（WSTC） <suP类="外部参照"&gt; 12，13，14被开发通过定义线性加速度随冲击持续时间的阈值的曲线边界正面碰撞时，预测为汽车撞车颅骨骨折。 WSTC曾担任其他伤害的标准，例如严重程度指数（SI）11基地 而头部伤害指数（HIC），15这是两种最常用的标准。的SI和HIC基于所述线性加速度 - 时间曲线加权积分两个量度影响严重性。而这些标准定义了线性加速度的阈值，其他的标准，已经提出以考虑转动加速度，如头部冲击功率索引。 8，10，16今天的头盔测试标准通常使用基于韦恩州立要伤害标准lerance曲线（即HIC或SI）或峰值加速度标准或在某些情况下，这两个。虽然需要一些修改角加速度添加到标准的性能标准，基于线性加速度标准仍然占主导地位。 在这项研究中，使用的指标来评估的相对安全性，所提供的每个头盔是峰值所得加速度，SI和HIC值。这些指标中，只有SI是用于当前全国工作委员会标准田径设备（NOCSAE）橄榄球头盔的标准评价。在SI是基于以下等式， <img alt="式（1）" src="/files/ftp_upload/53929/53929eq1.jpg" width="100" /> （1） 其中A是重力的头部的中心（CG）的平移加速度，和t是加速度的持续时间。 11，17 SI计算根据:õNOCSAE标准18，其中，计算由沿所得加速度曲线的4G阈限定。的HIC值通过下列公式计算， <img alt="式（1）" src="/files/ftp_upload/53929/53929eq2.jpg" width="325" /> （2） 其中a是头部的重心的平移加速度，和叔 1和t 2是最初和最后的时间，分别在其HIC达到最大值的时间间隔的。所有的HIC值在这项研究中分别为HIC 36，其中该时间间隔的持续时间被限制为36毫秒计算的。 NOCSAE橄榄球头盔测试标准 NOCSAE概述 1969年NOCSAE成立，以开发用于美式橄榄球头盔/ faceguards等运动设备，减少运动伤害的目标性能标准。 17 NOCSAE橄榄球头盔标准由韦恩州立大学的沃伊特霍奇森博士9人开发的建立影响衰减和结构的完整性要求橄榄球头盔/ faceguards，以减少头部受伤。这些橄榄球头盔标准包括认证测试和头盔年度换发新证手续。到2015年，实现NOCSAE需要使用特定的美国国家标准协会（ANSI）认可的机构头盔认证的质量保证计划。 NOCSAE测试方法 该NOCSAE橄榄球头盔标准不包括与faceguards头盔的测试，因为它正在开展头盔滴之前要求其删除。所述NOCSAE头盔测试标准17利用依赖于重力，以加速头模和头盔组合到所需冲击速度双线滴撞击。该NOCSAE头模的仪表W¯¯在重心i个三轴加速度计。头型和头盔的组合，然后在特定的速度下降到覆盖着厚12.7mm的硬质橡胶弹性体的模块化编程（MEP）垫钢砧。在冲击，瞬时加速度被记录和计算的SI值。这些SI值是针对一通比较/失败的标准在各种需要的撞击位置和速度以及两个温度，包括环境和高温的影响。如果任何影响所产生的SI值超出阈值，则该头盔将无法通过测试。 一个单独的标准测试方法用于足球甲头盔认证。所述NOCSAE足球面甲标准包括结构完整性分析以及评估所述面甲，南极的冲击衰减性能，和它们的附连系统。每一次撞击测试必须低于1200 SI通过测试，没有正面接触，也没有我任何部件的机械故障，如由NOCSAE标准定义的。 19 有一个提议增加NOCSAE测试（线性冲击器（LI））20，其中包括与面甲头盔，而是因为它不能承认冠的影响是不恰当的橄榄球头盔认证。对LI使用一个气动推杆撞击位于配备以诱导角加速度安装在一个线性轴承表的混合动力车第三虚设颈部NOCSAE头模头盔。由于这个原因，李试验是额外的试验，以目前的双网NOCSAE跌落试验过程而不是替代。 20，21相反的李测试中，我们提出简单地两个场景添加到当前双网跌落试验过程。 足球头盔认证NOCSAE标准测试方法目前包括六个规定的影响LOCAtions和单随机冲击的位置。该规定的撞击位置包括以下内容:前（F），前老板（FB），侧面（S），后（R），后老板（RB）和上衣（T）。随机冲击位置试验可以从头盔的规定的可接受影响区域内的任何点选择一个区域。我们修改NOCSAE落塔试验的撞击位置包括什么被命名为前上（FT）和前大老板（FTB）撞击位置替换先前定义的接待和前老板撞击位置。我们前面顶板和前大老板撞击位置相同，为长曲棍球头盔的NOCSAE标准和右前老板撞击位置，其中也包括跌落试验的面甲。 22头盔壳冲击地点，包括被替换的正面和前老板位置，在图1中描绘。 此外，我们目前的研究修改安全帽测试方法包括两个面甲IMPAC这被命名为FG接待和FG底部T形的位置。两个面甲的影响的位置是相同的，为当前NOCSAE面甲认证程序所需的冲击的位置。用于本研究的改性NOCSAE冲击测试八个撞击位置示于图2。 <img alt="图1" src="/files/ftp_upload/53929/53929fig1.jpg" /> 图1:橄榄球头盔近似撞击位置。这六个当前所需要NOCSAE跌落试验头盔撞击位置，前（F），前老板（FB），侧面（S），上衣（T），后（R）和后部凸台（RB），和两个建议撞击位置，前顶（FT）和前大老板（FTB）。注:安全帽的NOCSAE标准测试方法不包括前顶板和前大老板撞击位置（以红色文字显示），本研究中，他们更换前和前老板撞击位置。 （图片来自NOCSAE DOC修改。001-13m15b） <aHREF ="https://www.jove.com/files/ftp_upload/53929/53929fig1large.jpg"目标="_空白"&gt;点击此处查看该图的放大版本。 <img alt="图2" src="/files/ftp_upload/53929/53929fig2.jpg" /> 图2: 修改NOCSAE跌落测试设置显示8次位置。前顶，前顶boss，边，面甲（FG）正投，背投，背投老大，顶部和底部面甲（FB）。注:NOCSAE标准不包括面甲附件，这里接待顶板和前大老板取代标准的接待和前老板撞击位置。 （图片来自NOCSAE DOC修改。002-11m12） <a href="https://www.jove.com/files/ftp_upload/53929/53929fig2large.jpg" target="_blank">点击此处查看该图的放大版本。</a> 头盔设计在过去十年中已逐步改变，而NOCSAE足球头盔标准从未附带小时面甲ELMET在评价足球头盔性能规格。虽然，最近一项修正案已取得包括合格/不合格的最低速度的影响（3.46米/秒），一般通过/失败1200 SI的上限300 SI的价值自1997年17 1997年之前并没有改变，该NOCSAE使用1500 SI PASS / FAIL标准。 Hodgson 等人。 （1970年）显示，大于1000的SI值是对生命的危险，而540 SI值非头盔尸体碰撞试验已经产生线性颅骨骨折。 23最现代化的橄榄球头盔表明通过远低于1200 SI限制，但不是全部低于540 SI。

<table>
	<tbody>
		<tr>
			<td>PCB Triaxial Accelerometers</td>
			<td>PCB</td>
			<td>Model 353B17</td>
			<td></td>
		</tr>
		<tr>
			<td>TDAS2 Data Acqusition System</td>
			<td>Diversified Technical Systems, Inc.&#160;</td>
			<td>TDAS2</td>
			<td>Or an equivalent Data Acquisition System</td>
		</tr>
		<tr>
			<td>Current Source (Amplifier)&#160;</td>
			<td>Dytran Instruments, Inc.</td>
			<td>4114B1</td>
			<td>Or equivalent</td>
		</tr>
		<tr>
			<td>Velocity gate and flag</td>
			<td>CADEX</td>
			<td>SB203</td>
			<td>Or an equivalent velocimeter</td>
		</tr>
		<tr>
			<td colspan="2">Selected Football Helmet(s)/faceguard assem.</td>
			<td></td>
			<td>including chinstrap and faceguard hardware</td>
		</tr>
		<tr>
			<td>Height Gauge</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Torque wrench</td>
			<td>Snap-on</td>
			<td>QD21000</td>
			<td>range to 200 in/lb minimum, 5 % accuracy</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td colspan="4">Twin-wire Guide Assembly</td>
		</tr>
		<tr>
			<td>Drop Carriage&#160;</td>
			<td>SIRC</td>
			<td>1001</td>
			<td></td>
		</tr>
		<tr>
			<td>1/2&#34; MEP Testing Pad</td>
			<td>SIRC</td>
			<td>1006</td>
			<td></td>
		</tr>
		<tr>
			<td>1/8&#34; Faceguard Testing Pad</td>
			<td>SIRC</td>
			<td>1007</td>
			<td></td>
		</tr>
		<tr>
			<td>3&#34; MEP Calibration Pad</td>
			<td>SIRC</td>
			<td>1005</td>
			<td>Including Annual NOCSAE Calibration Pad Qualification Report</td>
		</tr>
		<tr>
			<td>3/8&#34; Hook-eye Turnbuckle</td>
			<td>SIRC</td>
			<td>1043</td>
			<td>Forged Steel with a 6&#34; take-up&#160;</td>
		</tr>
		<tr>
			<td>1/8&#34; Wire Rope Thimble&#160;</td>
			<td>SIRC</td>
			<td>1044</td>
			<td></td>
		</tr>
		<tr>
			<td>1/8&#34; Spring Music Wire&#160;</td>
			<td>SIRC</td>
			<td>1045</td>
			<td></td>
		</tr>
		<tr>
			<td>1/8&#34; Wire Rope, Tiller Rope Clamp, Bronze&#160;</td>
			<td>SIRC</td>
			<td>1046</td>
			<td></td>
		</tr>
		<tr>
			<td>3/8&#34; 16 x 3 &#8220; Eye Bolt&#160;</td>
			<td>SIRC</td>
			<td>1041</td>
			<td></td>
		</tr>
		<tr>
			<td>3/8&#34; Forged Eye Bolt</td>
			<td>SIRC</td>
			<td>1040</td>
			<td></td>
		</tr>
		<tr>
			<td>Right Angle DC Hoist Motor&#160;</td>
			<td>SIRC</td>
			<td>2000</td>
			<td></td>
		</tr>
		<tr>
			<td>Single Groove Sheave (Pulley), 3 &#190;&#34;&#160;</td>
			<td>SIRC</td>
			<td>2002</td>
			<td></td>
		</tr>
		<tr>
			<td>Top Mount Plate</td>
			<td>SIRC</td>
			<td>2003</td>
			<td></td>
		</tr>
		<tr>
			<td>18&#34; Top Channel Bracket&#160;</td>
			<td>SIRC</td>
			<td>2004</td>
			<td></td>
		</tr>
		<tr>
			<td>Wall Mount Channel Bracket, 4&#39; x 1 5/8&#34;&#160;</td>
			<td>SIRC</td>
			<td>2005</td>
			<td></td>
		</tr>
		<tr>
			<td>Mechanical Release System&#160;</td>
			<td>SIRC</td>
			<td>2006</td>
			<td></td>
		</tr>
		<tr>
			<td>Lift Cable, Wire Rope, 20&#39; Coil&#160;</td>
			<td>SIRC</td>
			<td>2007</td>
			<td></td>
		</tr>
		<tr>
			<td>Anvil Base Plate&#160;</td>
			<td>SIRC</td>
			<td>2010</td>
			<td></td>
		</tr>
		<tr>
			<td>Anvil&#160;</td>
			<td>SIRC</td>
			<td>2011</td>
			<td></td>
		</tr>
		<tr>
			<td>Headform Adjuster&#160;</td>
			<td>SIRC</td>
			<td>2012</td>
			<td></td>
		</tr>
		<tr>
			<td>Headform Rotator Stem</td>
			<td>SIRC</td>
			<td>2013</td>
			<td></td>
		</tr>
		<tr>
			<td>Headform Threaded Lock ring</td>
			<td>SIRC</td>
			<td>2016</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;Headform Collar&#160;</td>
			<td>SIRC</td>
			<td>2014</td>
			<td></td>
		</tr>
		<tr>
			<td>Nylon Bushing&#160;</td>
			<td>SIRC</td>
			<td>1803</td>
			<td></td>
		</tr>
		<tr>
			<td>Small Headform&#160;</td>
			<td>SIRC</td>
			<td>1100</td>
			<td></td>
		</tr>
		<tr>
			<td>Medium Headform&#160;</td>
			<td>SIRC</td>
			<td>1101</td>
			<td></td>
		</tr>
		<tr>
			<td>Large Headform</td>
			<td>SIRC</td>
			<td>1102</td>
			<td></td>
		</tr>
		<tr>
			<td>Taper-Loc Bolt</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>DC Motor Speed Controller (Reversible)&#160;</td>
			<td>SIRC</td>
			<td>2001</td>
			<td></td>
		</tr>
	</tbody>
</table>

modified drop tower impact tests for american football helmets

A modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test method for American football helmet drop impact test standards is presented that would provide better assessment of a helmet's on-field impact performance by including a faceguard on the helmet. In this study, a merger of faceguard and helmet test standards is proposed. The need for a more robust systematic approach to football helmet testing procedures is emphasized by comparing representative results of the Head Injury Criterion (HIC), Severity Index (SI), and peak acceleration values for different helmets at different helmet locations under modified NOCSAE standard drop tower tests. Essentially, these comparative drop test results revealed that the faceguard adds a stiffening kinematic constraint to the shell that lessens total energy absorption. The current NOCSAE standard test methods can be improved to represent on-field helmet hits by attaching the faceguards to helmets and by including two new helmet impact locations (Front Top and Front Top Boss). The reported football helmet test method gives a more accurate representation of a helmet's performance and its ability to mitigate on-field impacts while promoting safer football helmets.

结果此方法的详细定量分析拉什等人提出。 （提交）的结果的概要和一个耦合面甲-壳头盔测试方法的相关联的有效性被显示在使用罗林斯量子另外，里德尔360，舒特离子4D和Xenith X2头盔作为例子跌落试验结果。这些头盔与faceguards显示不同的结果（大小的"大"）的每个相比没有faceguards头盔。 图3比较绘制每个例子头盔的SI值有和没有5.46米/秒的冲?...

Watch this Scientific Journal Video about Modified Drop Tower Impact Tests for American Football Helmets at JoVE.com

Modified Drop Tower Impact Tests for American Football Helmets

This article provides a novel technique to assess the performance characteristics of American football helmets by inclusion of faceguards during NOCSAE Standard drop tests. Additionally, two more impact locations are proposed to be added to the NOCSAE certification.

修改落塔冲击试验为美国橄榄球头盔

A modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test method for American football helmet drop impact test standards ...

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10.8K 次观看.  Mississippi State University. This article provides a novel technique to assess the performance characteristics of American football helmets by inclusion of faceguards during NOCSAE Standard drop tests. Additionally, two more impact locations are proposed to be added to the NOCSAE certification. 

视频: Modified Drop Tower Impact Tests for American Football Helmets

A Simple Hanging Drop Cell Culture Protocol for Generation of 3D Spheroids

Studies of cell-cell cohesion and cell-substratum adhesion have historically been performed on monolayer cultures adherent to rigid substrates. Cells within a tissue, however, are typically encased within a closely packed tissue mass in which cells establish intimate connections with many near-neighbors and with extracellular matrix components. Accordingly, the chemical milieu and physical forces experienced by cells within a 3D tissue are fundamentally different than those experienced by cells grown in monolayer culture. This has been shown to markedly impact cellular morphology and signaling. Several methods have been devised to generate 3D cell cultures including encapsulation of cells in collagen gels1or in biomaterial scaffolds2. Such methods, while useful, do not recapitulate the intimate direct cell-cell adhesion architecture found in normal tissues. Rather, they more closely approximate culture systems in which single cells are loosely dispersed within a 3D meshwork of ECM products. Here, we describe a simple method in which cells are placed in hanging drop culture and incubated under physiological conditions until they form true 3D spheroids in which cells are in direct contact with each other and with extracellular matrix components. The method requires no specialized equipment and can be adapted to include addition of any biological agent in very small quantities that may be of interest in elucidating effects on cell-cell or cell-ECM interaction. The method can also be used to co-culture two (or more) different cell populations so as to elucidate the role of cell-cell or cell-ECM interactions in specifying spatial relationships between cells. Cell-cell cohesion and cell-ECM adhesion are the cornerstones of studies of embryonic development, tumor-stromal cell interaction in malignant invasion, wound healing, and for applications to tissue engineering. This simple method will provide a means of generating tissue-like cellular aggregates for measurement of biomechanical properties or for molecular and biochemical analysis in a physiologically relevant model.

We describe a simple, rapid method of generating 3D tissue-like spheroids and their potential application to quantify differences in cell-cell interactions.

一个简单的悬滴细胞生成三维球体文化协议

Studies of cell-cell cohesion and cell-substratum adhesion have historically been performed on monolayer cultures adherent to rigid substrates. Cells ...

科研

生物工程

Hydrophobic Salt-modified Nafion for Enzyme Immobilization and Stabilization

Over the last decade, there has been a wealth of application for immobilized and stabilized enzymes including biocatalysis, biosensors, and biofuel cells.1-3 In most bioelectrochemical applications, enzymes or organelles are immobilized onto an electrode surface with the use of some type of polymer matrix. This polymer scaffold should keep the enzymes stable and allow for the facile diffusion of molecules and ions in and out of the matrix. Most polymers used for this type of immobilization are based on polyamines or polyalcohols - polymers that mimic the natural environment of the enzymes that they encapsulate and stabilize the enzyme through hydrogen or ionic bonding. Another method for stabilizing enzymes involves the use of micelles, which contain hydrophobic regions that can encapsulate and stabilize enzymes.4,5 In particular, the Minteer group has developed a micellar polymer based on commercially available Nafion.6,7 Nafion itself is a micellar polymer that allows for the channel-assisted diffusion of protons and other small cations, but the micelles and channels are extremely small and the polymer is very acidic due to sulfonic acid side chains, which is unfavorable for enzyme immobilization. However, when Nafion is mixed with an excess of hydrophobic alkyl ammonium salts such as tetrabutylammonium bromide (TBAB), the quaternary ammonium cations replace the protons and become the counter ions to the sulfonate groups on the polymer side chains (Figure 1). This results in larger micelles and channels within the polymer that allow for the diffusion of large substrates and ions that are necessary for enzymatic function such as nicotinamide adenine dinucleotide (NAD). This modified Nafion polymer has been used to immobilize many different types of enzymes as well as mitochondria for use in biosensors and biofuel cells.8-12 This paper describes a novel procedure for making this micellar polymer enzyme immobilization membrane that can stabilize enzymes. The synthesis of the micellar enzyme immobilization membrane, the procedure for immobilizing enzymes within the membrane, and the assays for studying enzymatic specific activity of the immobilized enzyme are detailed below.

This article will describe the procedure for synthesizing a hydrophobically modified Nafion enzyme immobilization membrane and how to immobilize proteins and/or enzymes within the membrane and test their specific activity.

固定化酶和稳定的疏水盐改性的Nafion

Over the last decade, there has been a wealth of application for immobilized and stabilized enzymes including biocatalysis, biosensors, and biofuel ...

3D Orbital Tracking in a Modified Two-photon Microscope: An Application to the Tracking of Intracellular Vesicles

The objective of this video protocol is to discuss how to perform and analyze a three-dimensional fluorescent orbital particle tracking experiment using a modified two-photon microscope1. As opposed to conventional approaches (raster scan or wide field based on a stack of frames), the 3D orbital tracking allows to localize and follow with a high spatial (10 nm accuracy) and temporal resolution (50 Hz frequency response) the 3D displacement of a moving fluorescent particle on length-scales of hundreds of microns2. The method is based on a feedback algorithm that controls the hardware of a two-photon laser scanning microscope in order to perform a circular orbit around the object to be tracked: the feedback mechanism will maintain the fluorescent object in the center by controlling the displacement of the scanning beam3-5. To demonstrate the advantages of this technique, we followed a fast moving organelle, the lysosome, within a living cell6,7. Cells were plated according to standard protocols, and stained using a commercially lysosome dye. We discuss briefly the hardware configuration and in more detail the control software, to perform a 3D orbital tracking experiment inside living cells. We discuss in detail the parameters required in order to control the scanning microscope and enable the motion of the beam in a closed orbit around the particle. We conclude by demonstrating how this method can be effectively used to track the fast motion of a labeled lysosome along microtubules in 3D within a live cell. Lysosomes can move with speeds in the range of 0.4-0.5 &#181;m/sec, typically displaying a directed motion along the microtubule network8.

In this video protocol we track - at high speed and in three dimensions - fluorescently labeled lysosomes within living cells, using the orbital tracking method in a modified two-photon microscope.

3d轨道跟踪的改进双光子显微镜之应用:细胞内的囊泡的跟踪

The objective of this video protocol is to discuss how to perform and analyze a three-dimensional fluorescent orbital particle tracking experiment using a ...

Gene Transfection toward Spheroid Cells on Micropatterned Culture Plates for Genetically-modified Cell Transplantation

To improve the therapeutic effectiveness of cell transplantation, a transplantation system of genetically modified, injectable spheroids was developed. The cell spheroids are prepared in a culture system on micropatterned plates coated with a thermosensitive polymer. A number of spheroids are formed on the plates, corresponding to the cell adhesion areas of 100 &#181;m diameter that are regularly arrayed in a two-dimensional manner, surrounded by non-adhesive areas that are coated by a polyethylene glycol (PEG) matrix. The spheroids can be easily recovered as a liquid suspension by lowering the temperature of the plates, and their structure is well maintained by passing them through injection needles with a sufficiently large caliber (over 27 G). Genetic modification is achieved by gene transfection using the original non-viral gene carrier, polyplex nanomicelle, which is capable of introducing genes into cells without disrupting the spheroid structure. For primary hepatocyte spheroids transfected with a luciferase-expressing gene, the luciferase is sustainably obtained in transplanted animals, along with preserved hepatocyte function, as indicated by albumin expression. This system can be applied to a variety of cell types including mesenchymal stem cells.

This protocol describes a cell transplantation system using genetically modified, injectable spheroids. Cell spheroids are cultured on micropatterned culture plates and recovered after gene introduction using polyplex nanomicelles. This system facilitates prolonged transgene expression from the transplanted cells in host animals while maintaining the innate function of the cells.

基因转染向着文化微模式球体板细胞基因修饰的细胞移植

To improve the therapeutic effectiveness of cell transplantation, a transplantation system of genetically modified, injectable spheroids was developed. ...

Visualizing Angiogenesis by Multiphoton Microscopy In Vivo in Genetically Modified 3D-PLGA/nHAp Scaffold for Calvarial Critical Bone Defect Repair

The reconstruction of critically sized bone defects remains a serious clinical problem because of poor angiogenesis within tissue-engineered scaffolds during repair, which gives rise to a lack of sufficient blood supply and causes necrosis of the new tissues. Rapid vascularization is a vital prerequisite for new tissue survival and integration with existing host tissue. The de novo generation of vasculature in scaffolds is one of the most important steps in making bone regeneration more efficient, allowing repairing tissue to grow into a scaffold. To tackle this problem, the genetic modification of a biomaterial scaffold is used to accelerate angiogenesis and osteogenesis. However, visualizing and tracking in vivo blood vessel formation in real-time and in three-dimensional (3D) scaffolds or new bone tissue is still an obstacle for bone tissue engineering. Multiphoton microscopy (MPM) is a novel bio-imaging modality that can acquire volumetric data from biological structures in a high-resolution and minimally-invasive manner. The objective of this study was to visualize angiogenesis with multiphoton microscopy in vivo in a genetically modified 3D-PLGA/nHAp scaffold for calvarial critical bone defect repair. PLGA/nHAp scaffolds were functionalized for the sustained delivery of a growth factor pdgf-b gene carrying lentiviral vectors (LV-pdgfb) in order to facilitate angiogenesis and to enhance bone regeneration. In a scaffold-implanted calvarial critical bone defect mouse model, the blood vessel areas (BVAs) in PHp scaffolds were significantly higher than in PH scaffolds. Additionally, the expression of pdgf-b and angiogenesis-related genes, vWF and VEGFR2, increased correspondingly. MicroCT analysis indicated that the new bone formation in the PHp group dramatically improved compared to the other groups. To our knowledge, this is the first time multiphoton microscopy was used in bone tissue-engineering to investigate angiogenesis in a 3D bio-degradable scaffold in vivo and in real-time.

Visualizing Angiogenesis by Multiphoton Microscopy In Vivo in Genetically Modified 3D-PLGA/nHAp Scaffold for Calvarial Critical Bone Defect Repair

Here, we present a protocol to visualize blood vessel formation in vivo and in real-time in 3D scaffolds by multiphoton microscopy. Angiogenesis in genetically modified scaffolds was studied in a murine calvarial critical bone defect model. More new blood vessels were detected in the treatment group than in controls.

多显微镜下的血管生成术在基因修饰的 3 d-PLGA/nHAp 支架上进行颅骨临界骨缺损修复

The reconstruction of critically sized bone defects remains a serious clinical problem because of poor angiogenesis within tissue-engineered scaffolds ...

Initial Evaluation of Antibody-conjugates Modified with Viral-derived Peptides for Increasing Cellular Accumulation and Improving Tumor Targeting

Antibody-conjugates (ACs) modified with virus-derived peptides are a potentially powerful class of tumor cell delivery agents for molecular payloads used in cancer treatment and imaging due to increased cellular accumulation over current ACs. During early AC in vitro development, fluorescence techniques and radioimmunoassays are sufficient for determining intracellular localization, accumulation efficiency, and target cell specificity. Currently, there is no consensus on standardized methods for preparing cells for evaluating AC intracellular accumulation and localization. The initial testing of ACs modified with virus-derived peptides is critical especially if several candidates have been constructed. Determining intracellular accumulation by fluorescence can be affected by background signal from ACs at the cell surface and complicate the interpretation of accumulation. For radioimmunoassays, typically treated cells are fractionated and the radioactivity in different cell compartments measured. However, cell lysis varies from cell to cell and often nuclear and cytoplasmic compartments are not adequately isolated. This can produce misleading data on payload delivery properties. The intravenous injection of radiolabeled virus-derived peptide-modified ACs in tumor bearing mice followed by radionuclide imaging is a powerful method for determining tumor targeting and payload delivery properties at the in vivo phase of development. However, this is a relatively recent advancement and few groups have evaluated virus-derived peptide-modified ACs in this manner. We describe the processing of treated cells to more accurately evaluate virus-derived peptide-modified AC accumulation when using confocal microscopy and radioimmunoassays. Specifically, a method for trypsinizing cells to remove cell surface bound ACs. We also provide a method for improving cellular fractionation. Lastly, this protocol provides an in vivo method using positron emission tomography (PET) for evaluating initial tumor targeting properties in tumor-bearing mice. We use the radioisotope 64Cu (t1/2 = 12.7 h) as an example payload in this protocol.

Viral-derived peptides coupled to antibody-conjugates (ACs) is an approach gaining momentum due to the potential of delivering molecular payloads with increased tumor cell accumulation. Utilizing common methods to evaluate peptide conjugation, AC and payload intracellular accumulation, and tumor targeting, this protocol helps researchers during the key initial development phases.

病毒衍生肽修饰抗体结合物对增强细胞积累和改善肿瘤靶向性的初步评价

Antibody-conjugates (ACs) modified with virus-derived peptides are a potentially powerful class of tumor cell delivery agents for molecular payloads used ...

Construction and Setup of a Bench-scale Algal Photosynthetic Bioreactor with Temperature, Light, and pH Monitoring for Kinetic Growth Tests

The optimal design and operation of photosynthetic bioreactors (PBRs) for microalgal cultivation is essential for improving the environmental and economic performance of microalgae-based biofuel production. Models that estimate microalgal growth under different conditions can help to optimize PBR design and operation. To be effective, the growth parameters used in these models must be accurately determined. Algal growth experiments are often constrained by the dynamic nature of the culture environment, and control systems are needed to accurately determine the kinetic parameters. The first step in setting up a controlled batch experiment is live data acquisition and monitoring. This protocol outlines a process for the assembly and operation of a bench-scale photosynthetic bioreactor that can be used to conduct microalgal growth experiments. This protocol describes how to size and assemble a flat-plate, bench-scale PBR from acrylic. It also details how to configure a PBR with continuous pH, light, and temperature monitoring using a data acquisition and control unit, analog sensors, and open-source data acquisition software.

This paper describes the assembly process and operation of a bench-scale photosynthetic bioreactor that can be used, in conjunction with other methods, to estimate pertinent kinetic growth parameters. This system continuously monitors the pH, light, and temperature using sensors, a data acquisition and control unit, and open-source data acquisition software.

用于动态生长测试的温度，光照和pH监测的台式藻类光合生物反应器的构建和设置

The optimal design and operation of photosynthetic bioreactors (PBRs) for microalgal cultivation is essential for improving the environmental and economic ...

Fragility Assessment of Bovine Cortical Bone Using Scratch Tests

Bone is a complex hierarchical material with five distinct levels of organization. Factors like aging and diseases like osteoporosis increase the fragility of bone, making it fracture-prone. Owing to the large socio-economic impact of bone fracture in our society, there is a need for novel ways to assess the mechanical performance of each hierarchical level of bone. Although stiffness and strength can be probed at all scales &#8211; nano-, micro-, meso-, and macroscopic &#8211; fracture assessment has so far been confined to macroscopic testing. This limitation restricts our understanding of bone fracture and constrains the scope of laboratory and clinical studies. In this research, we investigate the fracture resistance of bone from the microscopic to the mesoscopic length scales using micro scratch tests combined with nonlinear fracture mechanics. The tests are performed in the short longitudinal orientation on bovine cortical bone specimens. A meticulous experimental protocol is developed and a large number (102) of tests are conducted to assess the fracture toughness of cortical bone specimens while accounting for the heterogeneity associated with bone microstructure.

This study assesses the fracture toughness of bovine cortical bone at the sub-meso levels using microscopic scratch tests. This is an original, objective, rigorous, and reproducible method proposed to probe fracture toughness below the macroscopic scale. Potential applications are studying changes in bone fragility due to diseases like osteoporosis.

牛皮质骨脆性评估的划痕试验

Bone is a complex hierarchical material with five distinct levels of organization. Factors like aging and diseases like osteoporosis increase the ...

Fabrication and Characterization of Griffithsin-modified Fiber Scaffolds for Prevention of Sexually Transmitted Infections

Electrospun fibers (EFs) have been widely used in a variety of therapeutic applications; however, they have only recently been applied as a technology to prevent and treat sexually transmitted infections (STIs). Moreover, many EF technologies focus on encapsulating the active agent, relative to utilizing the surface to impart biofunctionality. Here we describe a method to fabricate and surface-modify poly(lactic-co-glycolic) acid (PLGA) electrospun fibers, with the potent antiviral lectin Griffithsin (GRFT). PLGA is an FDA-approved polymer that has been widely used in drug delivery due to its outstanding chemical and biocompatible properties. GRFT is a natural, potent, and safe lectin that possesses broad activity against numerous viruses including human immunodeficiency virus type 1 (HIV-1). When combined, GRFT-modified fibers have demonstrated potent inactivation of HIV-1 in vitro. This manuscript describes the methods to fabricate and characterize GRFT-modified EFs. First, PLGA is electrospun to create a fiber scaffold. Fibers are subsequently surface-modified with GRFT using 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS)chemistry. Scanning electron microscopy (SEM) was used to assess the size and morphology of surface-modified formulations. Additionally, a gp120 or hemagglutinin (HA)-based ELISA may be used to quantify the amount of GRFT conjugated to, as well as GRFT desorption from the fiber surface. This protocol can be more widely applied to fabricate fibers that are surface-modified with a variety of different proteins.

This manuscript describes the procedure to fabricate and characterize Griffithsin-modified poly(lactic-co-glycolic acid) electrospun fibers that demonstrate potent adhesive and antiviral activity against human immunodeficiency virus type 1 infection in vitro. Methods used to synthesize, surface-modify, and characterize the resulting morphology, conjugation, and desorption of Griffithsin from surface-modified fibers are described.

Griffithsin 修饰纤维支架预防性传播感染的制备与表征

Electrospun fibers (EFs) have been widely used in a variety of therapeutic applications; however, they have only recently been applied as a technology to ...

Visual Detection of Multiple Nucleic Acids in a Capillary Array

Multi-target, short time, and resource-affordable methodologies for the detection of multiple nucleic acids in a single, easy to operate test are urgently needed in disease diagnosis, microbial monitoring, genetically modified organism (GMO) detection, and forensic analysis. We have previously described the platform called CALM (Capillary Array-based Loop-mediated isothermal amplification for Multiplex visual detection of nucleic acids). Herein, we describe improved fabrication and performance processes for this platform. Here, we apply a small, ready-to-use cassette assembled by capillary array for multiplex visual detection of nucleic acids. The capillary array is pre-treated into a hydrophobic and hydrophilic pattern before fixing loop-mediated isothermal amplification (LAMP) primer sets in capillaries. After assembly of the loading adaptor, LAMP reaction mixture is loaded and isolated into each capillary, due to capillary force by a single pipetting step. The LAMP reactions are performed in parallel in the capillaries. The results are visually read out by illumination with a hand-held UV flashlight. Using this platform, we demonstrate monitoring of 8 frequently appearing elements and genes in GMO samples with high specificity and sensitivity. In summary, the platform described herein is intended to facilitate the detection of multiple nucleic acids. We believe it will be widely applicable in fields where high-throughput nucleic acid analysis is required.

This protocol describes the fabrication of a small, ready-to-use cassette that can be applied for visual detection of multiple nucleic acids in a single, test that is easy to operate. In this approach, a capillary array was used for multiplex and highly efficient detection of GMO targets.

毛细管阵列中多核酸的视觉检测

Multi-target, short time, and resource-affordable methodologies for the detection of multiple nucleic acids in a single, easy to operate test are urgently ...