The authors thank the EPSRC and Intelligent Energy Ltd for funding this project. PB also thanks the SCI for the award of a Messel Scholarship.

数据记录软件1.建立<ol><li>安装数据采集和电子表格软件安装到配有RS232串行端口的计算机。 </li><li>将计算机连接到使用合适的RS232连接器电缆的平衡（在此方法中计算机和平衡需要9针连接器）。余额通常会被连接到COM1。 </li><li>打开数据采集软件。 </li><li>要记录数据在电子表格（ 如 Excel）中，去&#39;模式&#39;，然后&#39;发送键击"，在"应用程序标题栏文字"输入电子表格软件的适当的名称，然后选择"EXCEL.EXE"在在"命令行"，然后按"OK"。复选标记应该出现在旁边的"模式"下拉菜单"发送键击"。 </li><li>转到"端口"，然后"设置"，并确保这些值适合于有问题的平衡，然后按"OK";。 </li><li>转到&#39;定义&#39;，然后&#39;定义输入数据记录结构"，并选择"结束记录事件"部分的"收到的数字字符"中的"开始记录事件"部分和"回车或CRLF接收到的&#39;，然后按"继续"。 </li><li>当一个题为"输入记录结构"对话框出现时，选择"每个数据记录包含一个单独的数据字段"，然后按"继续"。 </li><li>当一箱名为"输入记录定义编辑器 - 发送键击模式"出现:在区域，设置"输入滤波器"到"数字数据只有"和"字段后记键击"到"{选项卡} {分钟} {二} {左} {} DOWN"，然后按"OK"。 </li><li>转到&#39;定义&#39;，然后&#39;定义热键和热的行动"。选择热键1，然后选择热键操作"暂停WinWedge&#39;和转让本的"退格"热键按键，然后按好。 </li><li>转到"文件"，然后"另存为"，然后保存方法在适当的文件夹。 </li></ol> 2.实验装置<ol><li>加水玻璃碗直到大约¾满。然后，放置在一个温度控制的搅拌器热板，并加热到50℃的玻璃碗;另外，使用恒温控制的水浴。 </li><li>添加去离子水（5毫升）的50ml圆底烧瓶中，并位置这在水浴使得水在浴水平远高于水在烧瓶中的水平。 </li><li>插入温度计入圆底烧瓶颈部监测水温（平衡后，水的烧瓶中的温度通常为〜5℃比在加热板设定点以下）。 注意:设置是准备就绪时将烧瓶内的水的温度保持在10分钟的时间常数。 </li><li>装满去离子水的烧杯中。 </li&gt; <li>将一个空烧杯到数据记录平衡。 </li><li>构造从塑料片可以从烧杯的喷口上的数据记录平衡转移水到空烧杯的桥梁。确保塑料桥不与在数据记录平衡烧杯物理接触。 </li><li>填的500毫升的量筒中，用去离子水。 </li><li>同时覆盖开口端用戴手套的手，反转量筒并放入烧杯中，使得所述测量圆筒的开口端仅仅是水的表面下。 </li><li>使用配有两个老板一个铁架台和夹具支持量筒。根据测量圆筒的大小，蒸馏的基础上发生的配重放置，以防止它由于掉落到水的重量。 </li><li>调整烧杯，使得喷口与所述塑料桥接触的位置。 </li><li>小心抬起量筒到llow的水和空气的进入释放以确保空气的测量圆筒中的水平是在每个实验开始时是一致的（例如100毫升的空气）。 </li><li>插入修饰的适配器的非磨口玻璃接头的一端插入管的长度。通过仔细地包装封口膜围绕接头和管道之间的连接密封。 </li><li>插入管导入量筒的末尾。 </li><li>确保在加入过量的水会导致其流失到平衡中加入一些水到烧杯中。泄漏可以在烧杯的开口和塑料桥之间的连接在高流速发生。 </li><li>确保余额不清零。如果有必要，加一些水，以对数据记录平衡烧杯中。 </li><li>用天平，称出或0.05，0.10，0.15，0.20，或0.25克硅放入小玻璃瓶中;一些硅趋向于被截留在其内不使用塑料称重舟将烧瓶颈部当从称量舟加入到反应混合物中。这个问题是由代替迅速反转一个小的玻璃瓶中放入烧瓶颈部避免。 </li></ol> 3.实验步骤<ol><li> （5毫升，20％重量）添加氢氧化钠溶液至50ml圆底烧瓶中，并位置这在水浴使得水在浴水平远高于水在烧瓶中的水平。 </li><li>插入温度计入圆底烧瓶颈部监测溶液的温度（平衡后，水的在此设置中，烧瓶中的温度通常为〜5℃比在加热板设定点以下）。 </li><li>离开10分钟以达到平衡。 </li><li>平衡期结束前，打开电子表格软件新的电子表格，然后打开数据收集软件。通过转到"文件"上的数据采集软件加载在步骤1中创建的方法开始菜单，然后"打开方式"。 </li><li>就在这10分钟的平衡期是由于结束，进入"激活"，然后点击"普通模式"。数据将开始在电子表格软件被记录。 </li><li>在10分钟的平衡周期结束时，通过迅速反转玻璃小瓶中，并在沉积所述硅进氢氧化钠溶液中添加硅。 </li><li>迅速放置其连接到管道成圆形的颈部适配器的磨口玻璃接头底烧瓶中。零平衡。在该天平归零的时刻将作为在数据分析时间（t）= 0。 </li><li> 10分钟过去了之后，按退格键，然后选择数据采集软件菜单上的"退出"选项停止对数据记录。保存在电子表格软件包中的文件。 </li><li>除去附着在管路从圆底烧瓶中的适配器并加水至阙NCH​​反应。 </li><li>通过离心或重力过滤分离在烧瓶中用于进一步分析的固体残余物​​中，或在整个反应混合物转移到烧杯中，并用盐酸（1 M）中和，并适当的废物处理。 </li></ol> 4.数据分析<ol><li>确保数据被加载到适当的电子表格软件包。 </li><li>寻找在天平归零的点;这被认为是（T）= 0点的反应。 </li><li>删除这之前该数据。 </li><li>插入一列到该数据的左侧。这将包含时间。 </li><li>添加适当的时间间隔，从0开始，向其中已插入的列。在这些研究中所用的平衡记录8.5个数据点每秒，并用于从而0.117647（= 1 / 8.5）秒的时间间隔。 </li><li>已收集的水考虑气体与水蒸汽饱和。在收集离子的过程中，测量圆筒中水位调整至保持在大气压力的测量圆筒中的内部压力。 </li><li>申请使用道尔顿定律，其中指出，在一个混合物中的气体（P 1 ... P N）的各个分压的总和等于总压力（P 合计 ）的近似校正因子。如，如果室内温度为298 K，水蒸汽的分压为31,69.9帕，并且测量圆筒中的气体的总压力为大气压（101325帕），它可以计算出有大约3.08％由所收集的气体中的体积的水蒸汽。通过使用水蒸汽的分压力在有关温度估计在其他温度下的氢的水蒸汽的量。 </li><li>以获得所产生的氢气的量的估计（如果室内温度是298K），乘以0.97的气体体积。 </li><li>估计最初的水力通过拟合线性趋势线的氢产生曲线的初始陡坡发电机产生率。 </li><li>取诱导期为采取对水的时间来从量筒位移。诱导期的这些估计都不是绝对的;实际氢产生反应在这些实验中估计为氢的一定量必须生成能够开始置换水的"诱导期"的结束前开始。然而，这些值允许在实验之间诱导期的相对的变化的评估。 </li></ol>

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Hydrogen Energ. 39, 1648-1663 (2014).</li><li>Cheng, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+active+nanoporous+Co-B-TiO2+framework+for+hydrolysis+of+NaBH4.">Highly active nanoporous Co-B-TiO2 framework for hydrolysis of NaBH4.</a> Ceram. Int. 41, 899-905 (2015).</li><li>Chinnappan, A., Kim, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanocatalyst:+Electrospun+nanofibers+of+PVDF+-+Dicationic+tetrachloronickelate+(II)+anion+and+their+effect+on+hydrogen+generation+from+the+hydrolysis+of+sodium+borohydride.">Nanocatalyst: Electrospun nanofibers of PVDF - Dicationic tetrachloronickelate (II) anion and their effect on hydrogen generation from the hydrolysis of sodium borohydride.</a> Int. J. Hydrogen Energ. 37, 18851-18859 (2012).</li><li>Shang, Y., Chen, R., Jiang, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetic+study+of+NaBH4+hydrolysis+over+carbon-supported+ruthenium.">Kinetic study of NaBH4 hydrolysis over carbon-supported ruthenium.</a> Int. J. Hydrogen Energ. 33, 6719-6726 (2008).</li><li>Shang, Y., Chen, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Semiempirical+Hydrogen+Generation+Model+Using+Concentrated+Sodium+Borohydride+Solution.">Semiempirical Hydrogen Generation Model Using Concentrated Sodium Borohydride Solution.</a> Energy Fuels. 20, 2149-2154 (2006).</li><li>Wang, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Promoted+Mo+incorporated+Co-Ru-B+catalyst+for+fast+hydrolysis+of+NaBH4+in+alkaline+solutions.">Promoted Mo incorporated Co-Ru-B catalyst for fast hydrolysis of NaBH4 in alkaline solutions.</a> Int. J. Hydrogen Energ. 39, 16202-16211 (2014).</li></ol>

The authors have nothing to disclose.

该协议的最重要的步骤是那些发生在一个实验的开始。这些水解反应的速率的大的温度依赖性意味着极大必须小心，以确保该溶液温度已在加入固体的前达到平衡。固体必须迅速并完全，适配器的磨口玻璃接头，必须正确插入圆底烧瓶的颈部，和余量然后必须尽可能迅速调零越好。的开始时间和反应温度的不正确的测量将产生不正确的结果。 该方法确实有一定的局限性。当务之急是插入量筒到其中的烧杯是尽可能的窄，以确保从量筒位移的水被迅速地引导向下塑料桥到平衡。否则，水的表面张力允许任意在低流速的水位的低积累（ 见图5），直到在该所有的水在一个大的滴被释放的点。 天平的误差也限制了数据的分辨率。在这些实验中，使用具有为±0.05克的错误的平衡，产生氢的数百毫升时，这是足够的，但如果正在测量较小体积具有较小误差的平衡将是需要的。 如从桥的位移水滴上的平衡，由天平记录质量产生振荡， 即 ，作为点滴落到平衡，平衡暂时记录一个稍大质量。这意味着使用的软件包高时间分辨率的原始数据的分化是有问题的梯度振荡。的最适当的方式找到氢产生曲线的最陡的部分的梯度，因此，氢生成速度，我s至适合的直线，并计算其梯度。 通过在电子表格自动登录的数据，该方法提供了精确度和时间分辨率相对于依赖于记录气体的手动放出的体积水置换方法显著改善。然而，虽然它在成本比它们使用相机和图像分析软件来跟踪气体放出方法相当低，这是在时间分辨率一般较低，并且这种基于相机的方法还避免了因水振荡质量平衡读数的问题形成液滴，因此，产生可以由分化更容易处理的数据。 水置换的方法是适用于在水中具有低溶解度的任何气体的集合。因此，该实验的协议可以被修改为从演进水溶性差的气体以外的化学反应产生气体的速率的测量上课。

由于它们的高能量密度，锂离子电池，目前最流行的电源为便携式消费电子之一。然而，可以由电池传递的能量的量是有限的。因此，存在目前正在制定提供便携式电源的替代方法的兴趣。一个更有前途的方法是利用质子交换膜（PEM）燃料电池，其通过组合氢和氧产生电和水。 PEM燃料电池有超过电池两大优点。首先，PEM燃料电池可以的时间长得多的周期提供电力（只要氢气流保持）。其次，这取决于燃料源上，PEM燃料电池可以具有比电池大得多的能量密度，这意味着一个较小的系统可以提供更多的能量。1,2-作为其结果，有一个目前定向的大量研究在开发可移植，按需氢源。2-7一种方法，它正在接收多的关注与水反应的化学物质是氢的生成。-8,9- 其中之一必须在这些反应进行测定的最重要的参数之一是氢的演变。对于简单的反应，例如氢气通过加入化学储氢材料以水溶液的演化，它有利的是具有一种简单的，低成本的测量系统。这种系统的一个例子是水置换方法，其中，在化学反应中产生的气体的体积是通过跟踪从一个倒置的充满水的量筒置换水的体积简单地进行测定。该技术起源于气动低谷，这是由植物学家斯蒂芬·黑尔斯开发，然后适应，并把它由约瑟夫·普利斯特里最有名的用于隔离的几种气体，包括氧气，在18 世纪 10,11水置换法适用于它是不溶于水，包括氢特别可溶的，并仍然被广泛用于记录从各种化学品，如硼氢化钠，铝和硅铁的反应产生氢气的体积，用水的任何气体。-12- 20 然而，经典的水中置换法，涉及在作为气体被放出的水位的变化人工记录，是乏味，并且可以在更高的气体流速，当水位急剧变化，是不准确的，因为它是难以实验者采取精确的读数。手工记录数据也是时间分辨率固有的低，作为实验者不能现实取读数更小的间隔比〜10秒。 一些研究人员通过使用摄像机来记录水位移过程和数据分析软件以提取在体积随时间的变化克服这个问题。21-25但是，该Requires计算机编程和相对昂贵的设备的知识。其他研究人员已经利用的质量流量计来记录氢气流26-29然而，这些往往只能够在一个窄的范围内检测气体，并且更适合于其中的流动被维持在一个相对恒定的应用水平。 以获得更高的分辨率更简单的方法，更准确的数据是到通道由氢气放出置换水进入其中放置在一个质量平衡接收机容器30-35本文描述该方法的变化是利用一般实验室级玻璃器皿和一种低成本，可商购天平从硅与氢氧化钠水溶液的反应记录析氢。而不是被手工记录，该数据被记录在使用数据收集软件包，它允许平衡发送数据到计算机中的电子表格。这应该注意，虽然该技术是适合于测量在毫升刻度析氢，它是不适合测量非常小（由于在平衡的不确定性），或非常大的（由于测量圆筒的大小有限）的卷氢气没有适当的调整（即使用更高的分辨率平衡或更大的量筒）。

<table border="0" cellpadding="0" cellspacing="0" width="582">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">WinWedge software</td>
			<td style="width:80px;">Taltech</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">http://www.taltech.com/winwedge</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">High Resolution Top Loader Balance</td>
			<td style="width:80px;">LW Measurements, LLC</td>
			<td style="width:119px;">HRB6001</td>
			<td>http://www.lwmeasurements.com/HRB-6001-High-Resoultion-Top-Loader-Balance-p/hrb6001.htm</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Silicon</td>
			<td style="width:80px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">215619</td>
			<td>325 mesh</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Sodium hydroxide</td>
			<td style="width:80px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">221465</td>
			<td>Reagent grade</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Aluminium (65.7%)-silicon (34.3%) alloy&#160;</td>
			<td style="width:80px;">Goodfellow</td>
			<td style="width:119px;">275-274-74</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Excel</td>
			<td style="width:80px;">Microsoft</td>
			<td style="width:119px;"></td>
			<td>https://products.office.com/en-us/excel</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Glass sample vials, 50x12mm</td>
			<td style="width:80px;">Scientific Laboratory Supplies</td>
			<td style="width:119px;">TUB1152</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Plastic sheet</td>
			<td style="width:80px;"></td>
			<td style="width:119px;"></td>
			<td>Recycled from a smooth-sided plastic drinks bottle</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Silicone tubing, 5x8mm BxO D</td>
			<td style="width:80px;">Scientific Laboratory Supplies</td>
			<td style="width:119px;">TUB3806</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Parafilm (2 in. by 250 ft.)</td>
			<td style="width:80px;">Sigma Aldrich</td>
			<td style="width:119px;">P7543</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Adapter</td>
			<td style="width:80px;">Sigma Aldrich</td>
			<td style="width:119px;">Z415685</td>
			<td>We used a custom-made adapter in our set-up, but this type of fitting would serve the same function</td>
		</tr>
	</tbody>
</table>

a simple, low-cost, and robust system to measure the volume of hydrogen evolved by chemical reactions with aqueous solutions

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) hydrogen fuel cells. Researchers seeking to develop such systems require a method of measuring the generated hydrogen. Herein, we describe a simple, low-cost, and robust method to measure the hydrogen generated from the reaction of solids with aqueous solutions. The reactions are conducted in a conventional one-necked round-bottomed flask placed in a temperature controlled water bath. The hydrogen generated from the reaction in the flask is channeled through tubing into a water-filled inverted measuring cylinder. The water displaced from the measuring cylinder by the incoming gas is diverted into a beaker on a balance. The balance is connected to a computer, and the change in the mass reading of the balance over time is recorded using data collection and spreadsheet software programs. The data can then be approximately corrected for water vapor using the method described herein, and parameters such as the total hydrogen yield, the hydrogen generation rate, and the induction period can also be deduced. The size of the measuring cylinder and the resolution of the balance can be changed to adapt the setup to different hydrogen volumes and flow rates.

调查实验装置的再现性，变化的硅的质量，用氢氧化钠水溶液反应以产生氢。每个反应一式三份进行。平均氢产生曲线示于图1。平均总氢气产量，氢生成速率，并归纳为硅的各质量周期也计算并与表示在图2中，3个标准差误差棒被绘制， 和图4，分别。有在反应之间的总氢气产量和氢气产生率非常小的偏差和偏差的在诱导期更高水平。 <img alt="图1" src="/files/ftp_upload/54383/54383fig1.jpg" /> 图1: 从Reacti制氢曲线的实施例硅上用氢氧化钠水溶液的。硅的各种质量（0.05，0.10，0.15，0.20和0.25克），用氢氧化钠水溶液在50℃下进行反应（5毫升，20重量％）。氢产生被记录为一个周期的10分钟。该反应一式三份进行，结果取平均值。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54383/54383fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图2" src="/files/ftp_upload/54383/54383fig2.jpg" /> 图 2: 从硅的用氢氧化钠水溶液反应氢气产量值的实施例的氢在10分钟内放出的总体积从氢产生曲线推导。获得并绘制为硅的各质量的平均总氢气产量。可以看出，有质量Ô之间的线性关系在反应和这些反应条件下产生的氢气的体积使用˚F硅。误差条表示总氢产量的一个标准差。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54383/54383fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图3" src="/files/ftp_upload/54383/54383fig3.jpg" /> 图 3: 从硅用氢氧化钠水溶液反应制氢速率值的实施例从氢产生曲线计算氢产生的硅的各质量的初始或最大速率。得到的硅的各质量平均初始或最大氢产生速率和绘图。可以看出，平均而言，存在在反应中使用的硅的质量和初始或最大氢g之间功率关系<html>这些反应条件下观察到的eneration速率。误差条表示的初始或最大氢气生成速率的一个标准偏差。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54383/54383fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图4" src="/files/ftp_upload/54383/54383fig4.jpg" /> 图 4: 从硅用氢氧化钠水溶液反应诱导期值的实施例的氢产生硅的各质量的诱导期是从氢产生曲线推导。获得并绘制的平均诱导期为硅的各质量。可以看出，平均而言，有在实验之间的诱导期没有很大的变化。误差棒代表初始或最大氢气生成速率的一个标准偏差。REF ="htt​​ps://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54383/54383fig4large.jpg"目标="_空白"&gt;点击此处查看该图的放大版本。 图5示出了从亚最佳实验一些代表性结果。在这种情况下，在滴液的积聚200和800秒的结果之间的氢气，由于水的表面张力的低流量，落在在大约400和710秒。虽然这些滴水不影响最大氢气生成速率的计算，如果，例如，测量停止的滴下降之前它们可能对总氢气产量的效果。因此，有必要要么改变反应条件（在此情况下，例如，通过加入铝 - 硅合金的较大的质量或使用的氢氧化钠的浓度较高），以确保气体的较高流动或反应设置，以防止滴的累积。 图5:一个次优实验例在本实验中，铝（65.7％） -硅（34.3％）的合金（0.2克）用氢氧化钠水溶液（5毫升，10重量％）在40℃下反应。虽然在氢气放出的初始高速率的氢产生的记录是最佳的，因为流动减慢形成的水的结果在滴的表面张力。该滴在处于大约400和710秒，在这种情况下， <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54383/54383fig5large.jpg" target="_blank">请点击这里查看该图的放大版本。</a>

Watch this Scientific Journal Video about A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions at JoVE.com

A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions

The study of methods to generate on-demand hydrogen for fuel cells continues to grow in importance. However, systems to measure hydrogen evolution from the reaction of chemicals with water can be complicated and expensive. This article details a simple, low-cost, and robust method to measure the evolution of hydrogen gas.

一种简单，低成本和强大的系统来测量氢气与水溶液化学反应放出的音量

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) ...

a-simple-low-cost-robust-system-to-measure-volume-hydrogen-evolved

Research

JoVE Journal

Chemistry

19.4K 次观看.  Loughborough University. The study of methods to generate on-demand hydrogen for fuel cells continues to grow in importance. However, systems to measure hydrogen evolution from the reaction of chemicals with water can be complicated and expensive. This article details a simple, low-cost, and robust method to measure the evolution of hydrogen gas.

视频: A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions

Free Radicals in Chemical Biology: from Chemical Behavior to Biomarker Development

The involvement of free radicals in life sciences has constantly increased with time and has been connected to several physiological and pathological processes. This subject embraces diverse scientific areas, spanning from physical, biological and bioorganic chemistry to biology and medicine, with applications to the amelioration of quality of life, health and aging. Multidisciplinary skills are required for the full investigation of the many facets of radical processes in the biological environment and chemical knowledge plays a crucial role in unveiling basic processes and mechanisms. We developed a chemical biology approach able to connect free radical chemical reactivity with biological processes, providing information on the mechanistic pathways and products. The core of this approach is the design of biomimetic models to study biomolecule behavior (lipids, nucleic acids and proteins) in aqueous systems, obtaining insights of the reaction pathways as well as building up molecular libraries of the free radical reaction products. This context can be successfully used for biomarker discovery and examples are provided with two classes of compounds: mono-trans isomers of cholesteryl esters, which are synthesized and used as references for detection in human plasma, and purine 5',8-cyclo-2'-deoxyribonucleosides, prepared and used as reference in the protocol for detection of such lesions in DNA samples, after ionizing radiations or obtained from different health conditions.

Radical-based biomimetic chemistry has been applied to building-up libraries necessary for biomarker development.

自由基化学生物学的化学行为，生物标记开发

The involvement of free radicals in life sciences has constantly increased with time and has been connected to several physiological and pathological ...

科研

化学

Isolation and Chemical Characterization of Lipid A from Gram-negative Bacteria

Lipopolysaccharide (LPS) is the major cell surface molecule of gram-negative bacteria, deposited on the outer leaflet of the outer membrane bilayer. LPS can be subdivided into three domains: the distal O-polysaccharide, a core oligosaccharide, and the lipid A domain consisting of a lipid A molecular species and 3-deoxy-D-manno-oct-2-ulosonic acid residues (Kdo). The lipid A domain is the only component essential for bacterial cell survival. Following its synthesis, lipid A is chemically modified in response to environmental stresses such as pH or temperature, to promote resistance to antibiotic compounds, and to evade recognition by mediators of the host innate immune response. The following protocol details the small- and large-scale isolation of lipid A from gram-negative bacteria. Isolated material is then chemically characterized by thin layer chromatography (TLC) or mass-spectrometry (MS). In addition to matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS, we also describe tandem MS protocols for analyzing lipid A molecular species using electrospray ionization (ESI) coupled to collision induced dissociation (CID) and newly employed ultraviolet photodissociation (UVPD) methods. Our MS protocols allow for unequivocal determination of chemical structure, paramount to characterization of lipid A molecules that contain unique or novel chemical modifications. We also describe the radioisotopic labeling, and subsequent isolation, of lipid A from bacterial cells for analysis by TLC. Relative to MS-based protocols, TLC provides a more economical and rapid characterization method, but cannot be used to unambiguously assign lipid A chemical structures without the use of standards of known chemical structure. Over the last two decades isolation and characterization of lipid A has led to numerous exciting discoveries that have improved our understanding of the physiology of gram-negative bacteria, mechanisms of antibiotic resistance, the human innate immune response, and have provided many new targets in the development of antibacterial compounds.

Isolation and characterization of the lipid A domain of lipopolysaccharide (LPS) from gram-negative bacteria provides insight into cell surface based mechanisms of antibiotic resistance, bacterial survival and fitness, and how chemically diverse lipid A molecular species differentially modulate host innate immune responses.

隔离和脂质A的化学表征革兰氏阴性菌

Lipopolysaccharide (LPS) is the major cell surface molecule of gram-negative bacteria, deposited on the outer leaflet of the outer membrane bilayer. LPS ...

A Simple and Rapid Protocol for Measuring Neutral Lipids in Algal Cells Using Fluorescence

Algae are considered excellent candidates for renewable fuel sources due to their natural lipid storage capabilities. Robust monitoring of algal fermentation processes and screening for new oil-rich strains requires a fast and reliable protocol for determination of intracellular lipid content. Current practices rely largely on gravimetric methods to determine oil content, techniques developed decades ago that are time consuming and require large sample volumes. In this paper, Nile Red, a fluorescent dye that has been used to identify the presence of lipid bodies in numerous types of organisms, is incorporated into a simple, fast, and reliable protocol for measuring the neutral lipid content of Auxenochlorella protothecoides, a green alga. The method uses ethanol, a relatively mild solvent, to permeabilize the cell membrane before staining and a 96 well micro-plate to increase sample capacity during fluorescence intensity measurements. It has been designed with the specific application of monitoring bioprocess performance. Previously dried samples or live samples from a growing culture can be used in the assay.

A simple protocol to determine the neutral lipid content of algal cells using a Nile Red staining procedure is described. This time-saving technique offers an alternative to traditional gravimetric-based lipid quantification protocols. It has been designed for the specific application of monitoring bioprocess performance.

一种简单快速的协议用荧光测量中性脂肪在藻细胞

Algae are considered excellent candidates for renewable fuel sources due to their natural lipid storage capabilities. Robust monitoring of algal ...

An Inverse Analysis Approach to the Characterization of Chemical Transport in Paints

The ability to directly characterize chemical transport and interactions that occur within a material (i.e., subsurface dynamics) is a vital component in understanding contaminant mass transport and the ability to decontaminate materials. If a material is contaminated, over time, the transport of highly toxic chemicals (such as chemical warfare agent species) out of the material can result in vapor exposure or transfer to the skin, which can result in percutaneous exposure to personnel who interact with the material. Due to the high toxicity of chemical warfare agents, the release of trace chemical quantities is of significant concern. Mapping subsurface concentration distribution and transport characteristics of absorbed agents enables exposure hazards to be assessed in untested conditions. Furthermore, these tools can be used to characterize subsurface reaction dynamics to ultimately design improved decontaminants or decontamination procedures. To achieve this goal, an inverse analysis mass transport modeling approach was developed that utilizes time-resolved mass spectroscopy measurements of vapor emission from contaminated paint coatings as the input parameter for calculation of subsurface concentration profiles. Details are provided on sample preparation, including contaminant and material handling, the application of mass spectrometry for the measurement of emitted contaminant vapor, and the implementation of inverse analysis using a physics-based diffusion model to determine transport properties of live chemical warfare agents including distilled mustard (HD) and the nerve agent VX.

In this paper, a procedure for quantifying the mass transport parameters of chemicals in various materials is presented. This process involves employing an inverse-analysis based diffusion model to vapor emission profiles recorded by real-time, mass spectrometry in high vacuum.

一个反分析方法化工运输的油漆表征

The ability to directly characterize chemical transport and interactions that occur within a material (i.e., subsurface dynamics) is a vital component in ...

Preparing Adherent Cells for X-ray Fluorescence Imaging by Chemical Fixation

X-ray fluorescence imaging allows us to non-destructively measure the spatial distribution and concentration of multiple elements simultaneously over large or small sample areas. It has been applied in many areas of science, including materials science, geoscience, studying works of cultural heritage, and in chemical biology. In the case of chemical biology, for example, visualizing the metal distributions within cells allows us to study both naturally-occurring metal ions in the cells, as well as exogenously-introduced metals such as drugs and nanoparticles. Due to the fully hydrated nature of nearly all biological samples, cryo-fixation followed by imaging under cryogenic temperature represents the ideal imaging modality currently available. However, under the circumstances that such a combination is not easily accessible or practical, aldehyde based chemical fixation remains useful and sometimes inevitable. This article describes in as much detail as possible in the preparation of adherent mammalian cells by chemical fixation for X-ray fluorescent imaging.

Here, we present a protocol on how to determine the quantity and distribution of metals in a sample using synchrotron X-ray fluorescence. We focus on adherent cells, and describe the chemical fixation method to prepare this sample. We then describe how to mount and image the sample using synchrotron X-rays.

化学固定准备贴壁细胞的X射线荧光成像

X-ray fluorescence imaging allows us to non-destructively measure the spatial distribution and concentration of multiple elements simultaneously over ...

Supercritical Nitrogen Processing for the Purification of Reactive Porous Materials

Supercritical fluid extraction and drying methods are well established in numerous applications for the synthesis and processing of porous materials. Herein, nitrogen is presented as a novel supercritical drying fluid for specialized applications such as in the processing of reactive porous materials, where carbon dioxide and other fluids are not appropriate due to their higher chemical reactivity. Nitrogen exhibits similar physical properties in the near-critical region of its phase diagram as compared to carbon dioxide: a widely tunable density up to ~1 g ml-1, modest critical pressure (3.4 MPa), and small molecular diameter of ~3.6 &#197;. The key to achieving a high solvation power of nitrogen is to apply a processing temperature in the range of 80-150 K, where the density of nitrogen is an order of magnitude higher than at similar pressures near ambient temperature. The detailed solvation properties of nitrogen, and especially its selectivity, across a wide range of common target species of extraction still require further investigation. Herein we describe a protocol for the supercritical nitrogen processing of porous magnesium borohydride.

Nitrogen is an effective supercritical fluid for extraction or drying processes due to its small molecular size, high density in the near-liquid supercritical regime, and chemical inertness. We present a supercritical nitrogen drying protocol for the purification treatment of reactive, porous materials.

超临界氮处理的活性多孔材料的净化

Supercritical fluid extraction and drying methods are well established in numerous applications for the synthesis and processing of porous materials. ...

Sulfate Separation by Selective Crystallization with a Bis-iminoguanidinium Ligand

A simple and effective method for selective sulfate separation from aqueous solutions by crystallization with a bis-guanidinium ligand, 1,4-benzene-bis(iminoguanidinium) (BBIG), is demonstrated. The ligand is synthesized as the chloride salt (BBIG-Cl) by in situ imine condensation of terephthalaldehyde with aminoguanidinium chloride in water, followed by crystallization as the sulfate salt (BBIG-SO4). Alternatively, BBIG-Cl is synthesized ex situ in larger scale from ethanol. The sulfate separation ability of the BBIG ligand is demonstrated by selective and quantitative crystallization of sulfate from seawater. The ligand can be recycled by neutralization of BBIG-SO4 with aqueous NaOH and crystallization of the neutral bis-iminoguanidine, which can be converted back into BBIG-Cl with aqueous HCl and reused in another separation cycle. Finally, 35S-labeled sulfate and &#946; liquid scintillation counting are employed for monitoring the sulfate concentration in solution. Overall, this protocol will instruct the user in the necessary skills to synthesize a ligand, employ it in the selective crystallization of sulfate from aqueous solutions, and quantify the separation efficiency.

A protocol for in situ aqueous synthesis of a bis(iminoguanidinium) ligand and its utilization in selective separation of sulfate is presented.

分离硫酸选择性结晶用双 -  iminoguanidinium配体

A simple and effective method for selective sulfate separation from aqueous solutions by crystallization with a bis-guanidinium ligand, ...

Green and Low-cost Production of Thermally Stable and Carboxylated Cellulose Nanocrystals and Nanofibrils Using Highly Recyclable Dicarboxylic Acids

Here we demonstrate potentially low cost and green productions of high thermally stable and carboxylated cellulose nanocrystals (CNCs) and nanofibrils (CNF) from bleached eucalyptus pulp (BEP) and unbleached mixed hardwood kraft pulp (UMHP) fibers using highly recyclable dicarboxylic solid acids. Typical operating conditions were acid concentrations of 50 - 70 wt% at 100 &#176;C for 60 min and 120 &#176;C (no boiling at atmospheric pressure) for 120 min, for BEP and UMHP, respectively. The resultant CNCs have a higher thermal degradation temperature than their corresponding feed fibers and carboxylic acid group content from 0.2 - 0.4 mmol/g. The low strength (high pKa of 1.0 - 3.0) of organic acids also resulted in CNCs with both longer lengths of approximately 239 - 336 nm and higher crystallinity than CNCs produced using mineral acids. Cellulose loss to sugar was minimal. Fibrous cellulosic solid residue (FCSR) from the dicarboxylic acid hydrolysis was used to produce carboxylated CNFs through subsequent mechanical fibrillation with low energy input.

Here we demonstrate a novel method for green and sustainable productions of highly thermally stable and carboxylated cellulose nanocrystals (CNC) and nanofibrils (CNF) using highly recyclable solid dicarboxylic acids.

热稳定和羧基化纤维素纳米晶和纳米原纤维使用高度可回收的二元羧酸绿色和低成本生产

Here we demonstrate potentially low cost and green productions of high thermally stable and carboxylated cellulose nanocrystals (CNCs) and nanofibrils ...

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

Direct cross-coupling between two alkenes via vinylic C-H bond activation represents an efficient strategy for the synthesis of butadienes with high atomic and step economy. However, this functionality-directed cross-coupling reaction has not been developed, as there are still limited directing groups in practical use. In particular, a stoichiometric amount of oxidant is usually required, producing a large amount of waste. Due to our interest in novel 1,3-butadiene synthesis, we describe the ruthenium-catalyzed olefination of electron-deficient alkenes using allyl acetate and without external oxidant. The reaction of 2-phenyl acrylamide and allyl acetate was chosen as a model reaction, and the desired diene product was obtained in 80% isolated yield with good stereoselectivity (Z,E/Z,Z = 88:12) under optimal conditions: [Ru(p-cymene) Cl2]2 (3 mol %) and AgSbF6 (20 mol %) in DCE at 110 &#186;C for 16 h. With the optimized catalytic conditions in hand, representative &#945;- and/or &#946;-substituted acrylamides were investigated, and all reacted smoothly, regardless of aliphatic or aromatic groups. Also, differently N-substituted acrylamides have proven to be good substrates. Moreover, we examined the reactivity of different allyl derivatives, suggesting that the chelation of acetate oxygen to the metal is crucial for the catalytic process. Deuterium-labeled experiments were also conducted to investigate the reaction mechanism. Only Z-selective H/D exchanges on acrylamide were observed, indicating a reversible cyclometalation event. In addition, a kinetic isotope effect (KIE) of 3.2 was observed in the intermolecular isotopic study, suggesting that the olefinic C-H metalation step is probably involved in the rate-determining step.

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

The ruthenium-catalyzed olefination of electron-deficient alkenes with allyl acetate is described here. By using aminocarbonyl as a directing group, this external oxidant-free protocol has high efficiency and good stereo- and regioselectivity, opening a novel synthetic route to (Z,E)-butadiene skeletons.

（2<em&gt;ž</em&gt;，4<em&gt;电子</em&gt;） - 通过电子缺陷烯烃与烯丙基乙酸酯的烯化反应制备二烯酰胺

Direct cross-coupling between two alkenes via vinylic C-H bond activation represents an efficient strategy for the synthesis of butadienes with high ...

Extraction of Ramie Fiber in Alkali Hydrogen Peroxide System Supported by Controlled-release Alkali Source

This protocol demonstrates a method for ramie fiber extraction by scouring raw ramie in an alkali hydrogen peroxide system supported by a controlled-release alkali source. The fiber extracted from ramie is a type of textile material of great importance. In previous studies, ramie fiber was extracted in an alkali hydrogen peroxide system supported only by sodium hydroxide.However, due to the strong alkalinity of sodium hydroxide, the oxidation reaction speed of hydrogen peroxide was difficult to control and thus resulted in great damage to the treated fiber. In this protocol, a controlled-release alkali source, which is composed of sodium hydroxide and magnesium hydroxide, is used to provide an alkali condition and buffer the pH value of the alkali hydrogen peroxidesystem. The substitution rate of magnesium hydroxide can adjust the pH value of the hydrogen peroxide system and has great influence on the fiber properties. The pH value and oxidation-reduction potential (ORP) value, which represents the oxidation ability of alkali hydrogen peroxide system, were monitored using a pH meter and ORP meter, respectively. The residual hydrogen peroxide content in the alkali hydrogen peroxide system during the extraction process and the chemical oxygen demand (COD) value of wastewater after fiber extraction are tested by KMnO4 titration method. The yield of fiber is measured using a precision electronic balance, and residual gums of fiber are tested by a chemical analysis method. The polymerization degree (PD value) of fiber is tested by an intrinsic viscosity method using the Ubbelohde viscometer. The tensile property of fiber, including tenacity, elongation, and rupture, is measured using a fiber strength instrument. Fourier transform infrared spectroscopy and X-ray diffraction are used to characterize the functional groups and crystal property of fiber. This protocol proves that the controlled-release alkali source can improve the properties of the fiber extracted in an alkali hydrogen peroxide system.

Presented here is a protocol for extraction of ramie fiber in alkali hydrogen peroxide system supported by controlled-release alkali source.