SR承认以色列科学基金会的支持下，不授予。十二分之二百八十零。

1，准备样品的碳<ol><li>磨碎碳样品所需部分尺寸（在此，煤样品研磨成之间74-250毫米的分数大小）。 </li><li>在磨削过程中砂轮机应在规范的环境中举行（AC冷却到20°C）。此外，吹扫研磨室用氮气之前研磨的流动在此阶段最小化氧化。 </li><li>转移碳样品可密封罐和更换空气气氛氮气。保持样本中的温度调节室（AC冷却至20℃）。 </li><li>通过在真空炉中加热该碳样品在惰性环境下制备的碳样品的EPR测量。 （为了除去吸附的水而制得。） </li><li>将每个样品在真空烘箱内开放的玻璃小瓶中（ 图1A）。 </li><li>关闭真空烤箱门，更换气氛在室内无线个氮气或氩气，然后加热至60℃。 </li><li>保持这些条件下放置24小时。 </li><li>关闭烘箱，并允许温度达到室温。然后，打开烤箱，取出样品瓶。 </li><li>塞子用橡胶隔片和铝盖（ 图1B）的样品小瓶中。 </li><li>使用真空系统（ 图1C），以除去氧气的所有痕迹。 </li><li>药瓶连接到系统并密封阀1-5。 </li><li>打开真空泵和压力表。 </li><li>打开阀1，等到显示器显示〜0.1毫巴的真空。 </li><li>确保泄漏极小，通过关闭阀1和计数到30，如果压力增加不大于3毫巴比系统的密封是足够的。 </li><li>开阀2和除去大气中的小瓶 - 等到压力返回到步骤1.14确定的初始压力值，并再次测试渗漏。 </li><li>如果有多个小瓶是贝因克做在同一时间（阀2-4）然后重复步骤1.15为每个阀门。 </li><li>实现真空和有效地清除剩余的气氛的小瓶中后，以期望的气体代替大气。 </li><li>关闭阀1，立即打开阀门5，让压力达到0.5个大气压。 </li><li>关闭阀5和开阀1，除​​去气体，等到返回到起始真空阀（吹扫1）。 </li><li>关闭阀1，立即打开阀门5，让压力达到0.5个大气压。 </li><li>关闭阀5，开阀1，除​​去气体，等到返回到起始真空阀（吹扫2）。 </li><li>关闭阀1，立即打开阀门5，让压力达到1.0个大气压，然后关闭阀门5。 </li><li>关闭阀2和向下轻轻拔出该针取出小瓶。 </li><li>除去小瓶打开阀1和后，从真空系统中清除的气体。 </li><li>在关闭真空泵，开阀2，以允许空气进入系统，并同时关闭所述泵（这防止了油的回流）。 </li></ol> 2，装入EPR3毫米石英管<ol><li>冲洗管的EPR用乙醇和干燥与N 2。 </li><li>从所需的煤样去除铝密封件。 </li><li>轻轻转动EPR管的开口端插入填充有碳样品的小瓶中。 </li><li>按下并转动EPR管，然后轻轻拍打，直到试样均匀分散在底部。 </li><li>填充管以这种方式高达至少1.5厘米的长度。 </li><li>轴封采用腻子约0.5-1.0厘米长（ 图2A）的橡胶腻子铁氟龙管的末端。 </li></ol> 3，设置流动系统<ol><li>将石英管放入EPR谐振器，请确保EPR管装满煤的部分填满整个谐振腔。 </li><li>这里报道的EPR测量是CONDucted在室温292-297 K。 </li><li>设置一个罐用所需流量的气体（N 2，CO 2，赫）确保有2个操作阀门，以控制流动（ 图2B）。 </li><li>连接橡胶管连接到油箱。确保该长度达到EPR石英管具有足够的拉力的前端，以便不把应变在石英管中。 </li><li>一个流量控制器连接到橡胶管来监测气体流动。 </li><li>通过使用小针头插入管通过橡胶特氟隆腻子。 </li><li>插入针头，直到它在接近（约3-4厘米以上的煤表面）的样品，但足够远从样品以免影响磁场（ 图2C）。 </li><li>离开流关闭（调整后只能打开流量）。 </li><li>戳在橡胶腻子的孔释放流出气体。 </li></ol> 4。EPR测量<ol><li>打开EPR谱仪之三。 </li><li>调整，没有气流。打开微波炉调节面板，找到浸达33.0 dB的功率，并使用自动调谐以获得最佳的调谐条件.. </li><li>将微波功率为2.0毫瓦，在这个功率没有饱和。 </li><li>开2D实验中，作为磁场和时间的函数。 </li><li>设置实验的参数如下: 微波功率为2.0毫瓦 调制振幅= 1.0克 时间常数= 60毫秒 扫描宽度= 100g的 延迟= 120秒 点的场扫描扫描= 1024号 点号作为时间= 50的函数</li><li>开始测量周期。 </li><li>打开气体流动。 </li><li>在样品达到平衡，并没有进一步的变化在EPR线的形状，这些参数后，分别测量它们之间的120秒的延迟，大约25 CW-EPR谱，停止气体流动。样品暴露在大气中，并继续进行测量，直到50秒pectra获得，或直至达到平衡。有停止燃气的流量后不需要再调整。测量自动继续，每个CW-EPR谱之间120秒的延迟。 </li><li>如果到达以较慢的速度平衡，增加点的数量作为时间的函数。 </li><li>如果达到以更快的速度的平衡，减少每次扫描之间的延迟时间。 </li></ol> 5。数据分析<ol><li>模拟使用MATLAB的23实施easyspin工具箱每个EPR场扫描光谱。采取两种考虑，在每个物种的g值，线宽，以及电子顺磁共振谱的贡献程度装有通过编写程序文件，如下所示: 清晰，CLF，CLC ％负载实验文件 expdata =负载（&#39;t0s.txt&#39;）; ％定义的物种一个自旋系统 SysC.g = 2.004; SysC.lwpp = 0.62; ％定义实验参数规格IES 1 Exp.mwFreq = 9.85764; ％以GHz Exp.Range = [347 357]; ％为mT Exp.Harmonic = 1; ％计算连续波EPR谱的生物种类之一 [BX，specX] =辣椒（SYSC，地契）; ％定义物种两个自旋系统 SysC2.g = 2.0028; SysC2.lwpp = 0.145; ％定义实验参数进行种内的两个 Exp2.mwFreq = 9.85764; Exp2.Range = [347 357]; Exp2.Harmonic = 1; ％计算连续波EPR谱种的两个 [BX2，specX2] =辣椒（SysC2，Exp2后）; X = 0:0.1:1; ％结合两个物种的光谱。 spectot = 1.0 * specX +0.0 * specX2; ％绘制实验和模拟光谱。 BX * 10，spectot，expdata（:，1），expdata（:，2））; </li></ol>

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没有利益冲突的声明。

碳材料的表面氧化是显著的工业和学术兴趣。碳底物氧化的影响已被鉴定具有广泛的分析技术，包括EPR。当调查的分子氧与碳基材如煤具有倾向发生氧化（因此它主要利用作为能源资源）的相互作用的样品制备和储存是极其重要的。 我们的样品是已经海外运送大型货舱为能源行业的煤炭利用基板。即使该样品在运输过程中由于发生一些氧化，我们试图通过随后将它们存储在N ...

不同的C / H / O原子（重量％）的比率基板目前不同类型和稳定的自由基，通过电子顺磁共振（EPR）是检测到的浓度8。这些基团依赖于大分子的结构和它们的芳族性质的高度影响。煤自由基的EPR光谱，其特征在于由单一的宽共振。在这种情况下，只对g值时，线条宽度和自旋浓度可以得到。 EPR谱的G-值可以被用于确定是否一个基是碳中心或氧为中心的。基本方程为电子塞曼相互作用<img alt="式（1）" fo:content-width="0.8in" src="/files/ftp_upload/51548/51548eq1.jpg" />定义的g值，其中h是普朗克常数，v是在实验中所施加的恒定MW频率，B 0是谐振磁场和βe为玻尔磁子。对于自由电子的g值是2.00232。 V在从2.00232的g值ariations涉及涉及未成对电子的轨道角动量，其化学环境的磁相互作用。有机基团通常具有G-值接近自由电子克，这取决于自由基在有机基质3，8-10的位置。碳中心自由基具有G-值是接近自由电子的g值2.0023。碳中心自由基与相邻的氧原子具有在2.003-2.004范围内较高的G-值，而中心的氧自由基具有G-数值&gt; 2.004。为2.0034-2.0039的g值的特征是碳中心自由基在附近的氧杂原子而导致增加的G-值较纯碳中心自由基11-15。线宽是由自旋 - 晶格驰豫过程支配。因此，相邻的基团之间或自由基与顺磁氧导致的减少之间的相互作用在自旋晶格弛豫时间，并因此增加了线宽4-6。 停止流动的实验与EPR检测允许观察在EPR信号在两个阶段通过时间扫描采集（动能显示）的相互作用过程中一个独特的字段值的振幅随时间变化。这种测量的结果是一个速率常数的形成，腐烂或转换的顺磁性物质。该过程是类似的完善与其中的光吸收在一个独特的波长的时间依赖性，观察光检测停止流的操作的情况。典型地停止流动实验以液体状态进行与未EPR在液体状态检测由于短的弛豫时间T 1的基团，如，例如羟基（OH×）或超氧化物（O 2 - ）不能直接由EPR-停止研究流技术。它是，但是，possibl<html> e来研究自旋加合物，这些基团与硝酮，产生氮氧自由基型（自旋过滤器），因为它们是EPR-活性和它们的动力学也可以监视由停止流动EPR 16-18。 利用快速流动的气体的技术与EPR检测化学反应速率的测量方法也曾被证实19-22。在本质上，该方法依赖于测量，通过EPR，反应物作为距离的函数的浓度（并因此以恒定的速度，时间）超过该反应物已在与反应气体接触的流管。条件，使反应气体的浓度是大致恒定的，通常采用使测得的衰减是假一级。 在目前的工作中，一个简单的气体流量设置实施和气体的恒定流量被引入到固体碳基体的表面。 ntent"&gt;有在当前工作中详述的方法，我们成功地实现了，其中分子氧与现有的稳定的自由基结构的某一部分的这种相互作用可以被可逆地简单地受到通过在STP下的碳样品流过一个反磁性气体有趣的结果。作为这种方法的结果是除去相互作用的顺磁性气体的揭示了新的基面有g值，这是更接近于自由电子。

<table border="0" cellpadding="0" cellspacing="0" width="629">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">EPR spectrometer</td>
			<td style="width:127px;">Bruker</td>
			<td style="width:119px;">Elexsys E500</td>
			<td></td>
		</tr>
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			<td height="22" style="height:22px;">EPR quartz tube</td>
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			<td height="22" style="height:22px;width:216px;">Custom made vacuum system&#160;</td>
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			<td height="21" style="height:21px;width:216px;">CO2&#160;&#160;&#160;&#160;&#160;&#160; 99.99%</td>
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			<td height="21" style="height:21px;width:216px;">N2&#160;&#160;&#160;&#160;&#160;&#160; 99.999%</td>
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			<td height="21" style="height:21px;width:216px;">Air</td>
			<td style="width:127px;">Maxima</td>
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		</tr>
	</tbody>
</table>

exploring the radical nature of a carbon surface by electron paramagnetic resonance and a calibrated gas flow

虽然第一电子顺磁共振（EPR）就氧化碳自由基的结构和稳定性影响的研究可以追溯到20世纪80年代初的早期论文的焦点主要特征的变化对结构极其恶劣的条件下（pH值或温度）1-3。它也被称为顺磁性分子氧经过与稳定自由基的海森堡自旋交换作用是极其开阔的EPR信号4-6。最近，我们报道，其中分子氧与现有的稳定的自由基结构的某一部分的这种相互作用可以被可逆地简单地受到通过在STP 7的碳样品流过一个反磁性气体有趣的结果。例如He，CO 2和N 2的流量也有类似的影响这些相互作用发生在大孔体系的表面积。 这个手稿突出了实验吨echniques，工作起来，对影响碳结构的现有稳定的自由基性质分析。希望这将有助于对在社区这些互动的在逃进一步发展和理解。

当预成型的各类煤样的EPR实验，作为曝光时间的函数的反磁性气体流有人指出，气体流动过程中，第二个物种在g〜2.0028出现。这g值是接近自由电子的值，并与未取代的脂族碳中心自由基一致。然而，总自旋浓度为每一个样品我们的实验误差范围内保持恒定（±10％） 图3A给出两个扫描:0秒和1,900秒后煤样已暴露于CO 2气体（HA）。电子顺磁共振谱1,900秒的特点是两个物种。一个在...

Watch this Scientific Journal Video about Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow at JoVE.com

Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow

稳定自由基存在于碳底物通过海森堡自旋交换与顺磁氧相互作用。这种相互作用可以显著STP条件下，通过在碳制流动的反磁性气体减少。这个手稿描述了一个简单的方法来描述这些自由基的性质。

通过电子顺磁共振和校准气体流量探索碳表面的激进性质

While the first Electron Paramagnetic Resonance (EPR) studies regarding the effects of oxidation on the structure and stability of carbon radicals date ...

exploring-radical-nature-carbon-surface-electron-paramagnetic

Universidad de Cartagena UDEC

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Organic Chemistry

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Unit 1

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10.7K 次观看.  The Hebrew University of Jerusalem. 稳定自由基存在于碳底物通过海森堡自旋交换与顺磁氧相互作用。这种相互作用可以显著STP条件下，通过在碳制流动的反磁性气体减少。这个手稿描述了一个简单的方法来描述这些自由基的性质。 

视频: Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow

Quantitative Detection of Trace Explosive Vapors by Programmed Temperature Desorption Gas Chromatography-Electron Capture Detector

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can account for instrumentation losses, which makes it ideal for minimizing variability and quantitative trace chemical detection. Gas chromatography with an electron capture detector is an instrumentation configuration sensitive to nitro-energetics, such as TNT and RDX, due to their relatively high electron affinity. However, vapor quantitation of these compounds is difficult without viable vapor standards. Thus, we eliminate the requirement for vapor standards by combining the sensitivity of the instrumentation with a direct liquid deposition protocol to analyze trace explosive vapor samples.

Trace explosive vapors of TNT and RDX collected on sorbent-filled thermal desorption tubes were analyzed using a programmed temperature desorption system coupled to GC with an electron capture detector. The instrumental analysis is combined with direct liquid deposition method to reduce sample variability and account for instrumentation drift and losses.

定量检测痕量爆炸物蒸气通过程序升温脱附 - 气相色谱 - 电子捕获检测器

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive ...

科研

化学

Real-time Monitoring of Reactions Performed Using Continuous-flow Processing: The Preparation of 3-Acetylcoumarin as an Example

By using inline monitoring, it is possible to optimize reactions performed using continuous-flow processing in a simple and rapid way. It is also possible to ensure consistent product quality over time using this technique. We here show how to interface a commercially available flow unit with a Raman spectrometer. The Raman flow cell is placed after the back-pressure regulator, meaning that it can be operated at atmospheric pressure. In addition, the fact that the product stream passes through a length of tubing before entering the flow cell means that the material is at RT. It is important that the spectra are acquired under isothermal conditions since Raman signal intensity is temperature dependent. Having assembled the apparatus, we then show how to monitor a chemical reaction, the piperidine-catalyzed synthesis of 3-acetylcoumarin from salicylaldehyde and ethyl acetoacetate being used as an example. The reaction can be performed over a range of flow rates and temperatures, the in-situ monitoring tool being used to optimize conditions simply and easily.

Real-time monitoring allows for fast optimization of reactions performed using continuous-flow processing. Here the preparation of 3-acetylcoumarin is used as an example. The apparatus for performing in-situ Raman monitoring is described, as are the steps required to optimize the reaction.

反应执行使用连续流处理的实时监控:3  - 乙酰基香豆素的制备为例

By using inline monitoring, it is possible to optimize reactions performed using continuous-flow processing in a simple and rapid way. It is also possible ...

Transport of Surface-modified Carbon Nanotubes through a Soil Column

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, electronics and biomedical applications. Due to their accelerating production and use, CNTs constitute a potential environmental risk if they are released to soil and groundwater systems. It is therefore essential to improve the current understanding of environmental fate and transport of CNTs. The transport and retention of CNTs in both natural and artificial media have been reported in literature, but the findings widely vary and are thus not conclusive. There are a number of physical and chemical parameters responsible for variation in retention and transport. In this study, a complete procedure of selected multiwalled carbon nanotubes (MWCNTs) is presented starting from their surface modification to a complete set of laboratory column experiments at critical physical and chemical scenarios. Results indicate that the stability of the commercially available MWCNTs are critical with their attached surface functional group which can also influence the transport and retention of MWCNT through the surrounding medium.

Surface properties of a nanoparticle are important for their interaction with the surrounding medium. Therefore the surface modification of carbon nanotubes can be critical for their transport and retention through porous media. Here, lab scale column experiments are used to understand the possible transport and retention of these nanoparticles.

表面修饰碳纳米管通过土柱运输

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, ...

A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where interfacial tension is a dominant force. A variety of methods exist for controlling the interfacial tension of aqueous and organic liquids on this scale; however, these techniques have limited utility for liquid metals due to their large interfacial tension.
Liquid metals can form soft, stretchable, and shape-reconfigurable components in electronic and electromagnetic devices. Although it is possible to manipulate these fluids via mechanical methods (e.g., pumping), electrical methods are easier to miniaturize, control, and implement. However, most electrical techniques have their own constraints: electrowetting-on-dielectric requires large (kV) potentials for modest actuation, electrocapillarity can affect relatively small changes in the interfacial tension, and continuous electrowetting is limited to plugs of the liquid metal in capillaries.
Here, we present a method for actuating gallium and gallium-based liquid metal alloys via an electrochemical surface reaction. Controlling the electrochemical potential on the surface of the liquid metal in electrolyte rapidly and reversibly changes the interfacial tension by over two orders of magnitude ( &#820;500 mN/m to near zero). Furthermore, this method requires only a very modest potential (&#60; 1 V) applied relative to a counter electrode. The resulting change in tension is due primarily to the electrochemical deposition of a surface oxide layer, which acts as a surfactant; removal of the oxide increases the interfacial tension, and vice versa. This technique can be applied in a wide variety of electrolytes and is independent of the substrate on which it rests.

We present a method to control the interfacial energy of a liquid metal in an electrolyte via electrochemical deposition (or removal) of a surface oxide layer. This simple method can control the capillary behavior of gallium-based liquid metals by tuning the interfacial energy rapidly, significantly, and reversibly using modest voltages.

方法通过表面氧化还原操纵液态金属的表面张力

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where ...

Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The procedure is performed under an inert atmosphere using air- and water-exclusion techniques. The outcome of the polymerization is affected by the ratios of monomer, initiator, and catalyst used as well as the reaction concentration, solvent, and nature of the light source. Temporal control over the polymerization can be exercised by turning the visible light source off and on. Low dispersities of the resultant polymers as well as the ability to chain-extend to form block copolymers suggest control over the polymerization, while chain end-group analysis provides evidence supporting an atom-transfer radical polymerization mechanism.

A method for the atom transfer radical polymerization of functionalized vinyl monomers using perylene as a visible-light photocatalyst is described.

使用苝作为可见光光催化功能化的乙烯基单体原子转移自由基聚合

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The ...

In Situ Monitoring of Diffusion of Guest Molecules in Porous Media Using Electron Paramagnetic Resonance Imaging

A method is demonstrated to monitor macroscopic translational diffusion using electron paramagnetic resonance (EPR) imaging. A host-guest system with nitroxide spin probe 3-(2-Iodoacetamido)-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (IPSL) as a guest inside the periodic mesoporous organosilica (PMO) aerogel UKON1-GEL as a host and ethanol as a solvent is used as an example to describe the protocol. Data is shown from a previous publication, where the protocol has been applied to both IPSL and Tris(8-carboxy-2,2,6,6-perdeutero-tetramethyl-benzo[1,2-d:4,5-d&#8242;]bis(1,3)dithiole) methyl (Trityl) as guest molecules and UKON1-GEL and SILICA-GEL as host systems. 
A method is shown to prepare aerogel samples that cannot be synthesized directly in the sample tube for measurement due to a size change during synthesis. The aerogel is attached to sample tubes using heat shrink tubing and a pressure cooker to reach the necessary temperature without evaporating the solvent in the process. The method does not assume a clearly defined initial distribution of guest molecules at the start of the measurement. Instead, it requires a reservoir on top of the aerogel and experimentally determines the influx rate during data analysis.
The diffusion is monitored continually over a period of 20 hr by recording the 1d spin density profile within the sample. The spectrometer settings for the imaging experiment are described quantitatively. Data analysis software is provided to take the resonator sensitivity profile into account and to numerically solve the diffusion equation. The software determines the macroscopic translational diffusion coefficient by least square minimization of the difference between the experiment and the numerical solution of the diffusion equation.

In Situ Monitoring of Diffusion of Guest Molecules in Porous Media Using Electron Paramagnetic Resonance Imaging

A protocol for the in situ monitoring of the diffusion of guest molecules in porous media using electron paramagnetic resonance (EPR) imaging is presented.

在多孔介质中使用电子顺磁共振成像客体分子扩散的原位监测

A method is demonstrated to monitor macroscopic translational diffusion using electron paramagnetic resonance (EPR) imaging. A host-guest system with ...

Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated, Threaded-rod

Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, this resolution provides records at the annual to decadal scale, at best. An extrusion method, using a calibrated, threaded-rod is presented here, which allows for millimeter-scale subsampling of aquatic sediment cores of varying diameters. Millimeter scale subsampling allows for sub-annual to monthly analysis of the sedimentary record, an order of magnitude higher than typical sampling schemes. The extruder consists of a 2 m aluminum frame and base, two core tube clamps, a threaded-rod, and a 1 m piston. The sediment core is placed above the piston and clamped to the frame. An acrylic sampling collar is affixed to the upper 5 cm of the core tube and provides a platform from which to extract sub-samples. The piston is rotated around the threaded-rod at calibrated intervals and gently pushes the sediment out the top of the core tube. The sediment is then isolated into the sampling collar and placed into an appropriate sampling vessel (e.g., jar or bag). This method also preserves the unconsolidated samples (i.e., high pore water content) at the surface, providing a consistent sampling volume. This mm scale extrusion method was applied to cores collected in the northern Gulf of Mexico following the Deepwater Horizon submarine oil release. Evidence suggests that it is necessary to sample at the mm scale to fully characterize events that occur on the monthly time-scale for continental slope sediments.

An extrusion method using a calibrated threaded-rod is presented, which allows for mm scale subsampling of aquatic sediment cores. Millimeter-scale sampling is necessary to fully characterize recent event stratigraphy in sediment records.

沉积物核心挤压法在毫米的分辨率用校准，螺纹杆

Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, ...

Failure of Cleaning Verification in Pharmaceutical Industry Due to Uncleanliness of Stainless Steel Surface

The aim of this work is to identify the parameters that affect the recovery of pharmaceutical residues from the surface of stainless steel coupons. A series of factors were assessed, including drug product spike levels, spiking procedure, drug-excipient ratios, analyst-to-analyst variability, intraday variability, and cleaning procedure of the coupons. The lack of a well-defined procedure that consistently cleaned the coupon surface was identified as the major contributor to low and variable recoveries. Assessment of cleaning the surface of the coupons with clean-in-place solutions (CIP) gave high recovery (&#62;90%) and reproducible results (Srel&#8804;4%) regardless of the conditions that were assessed previously. The approach was successfully applied for cleaning verification of small molecules (MW &#60;1,000 Da) as well as large biomolecules (MW up to 50,000 Da).

The lack of a well-defined procedure that consistently cleaned coupon surfaces was identified as the major contributor to low and variable recoveries in cleaning verification. This manuscript describes the correct protocol of cleaning stainless steel coupons.

清洁验证在不锈钢表面脏制药行业中的失败

The aim of this work is to identify the parameters that affect the recovery of pharmaceutical residues from the surface of stainless steel coupons. A ...

Grafting Multiwalled Carbon Nanotubes with Polystyrene to Enable Self-Assembly and Anisotropic Patchiness

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a free-radical polymerization strategy to enable the modulation of the nanotube surface properties and produce supramolecular self-assembly of the nanostructures. First, a selective hydroxylation of the pristine nanotubes through a biphasic catalytically mediated oxidation reaction creates superficially distributed reactive sites at the sidewalls. The latter reactive sites are subsequently modified with methacrylic moieties using a silylated methacrylic precursor to create polymerizable sites. Those polymerizable groups can address further polymerization of styrene to produce a hybrid nanomaterial containing PS chains grafted to the nanotube sidewalls. The polymer-graft content, amount of silylated methacrylic moieties introduced and hydroxylation modification of the nanotubes are identified and quantified by Thermogravimetric Analysis (TGA). The presence of reactive functional groups hydroxyl and silylated methacrylate are confirmed by Fourier Transform Infrared Spectroscopy (FT-IR). Polystyrene-grafted carbon nanotube solutions in tetrahydrofuran (THF) provide wall-to-wall collinearly self-assembled nanotubes when cast samples are analyzed by transmission electron microscopy (TEM). Those self-assemblies are not obtained when suitable blanks are similarly cast from analogous solutions containing non-grafted counterparts. Therefore, this method enables the modification of the nanotube anisotropic patchiness at the sidewalls which results into spontaneous auto-organization at the nanoscale.

A procedure for the synthesis of polystyrene-grafted multiwalled carbon nanotubes using successive chemical modification steps to selectively introduce the polymer chains to the sidewalls and their self-assembly via anisotropic patchiness is presented.

用聚苯乙烯接枝多壁纳米碳纳米管使自组装和各向异性斑块

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

电化学阻抗谱作为电化学速率常数估计的一种工具

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...