导致这些结果的研究得到了 NE/J010783/1 的资助。该项目 NanoValid 已收到欧洲联盟的第七项研究、技术发展方案和根据赠款协议 No. 263147 的示范计划的资金。

注: 所有的化学物质都是在没有进一步纯化的情况下使用的。在整个研究中使用超纯水, 电阻率为 18 MΩ·cm。所有准备好的分散体通常在黑暗中被储存在5° c 的任何进一步的表征或未来的稳定性研究, 但这可能会因材料组成和其他相关的性质, 如溶解。例如, 银 NPs 通常是稳定的一段时间, 如果储存在 2-5 ° c 远离阳光;然而, 动态变化必然会发生在悬浮体和分散体将 re-agglomerate, 但已知的泥沙随着时间的推移。在生物测试前使用 dl、UV 和 TEM 对这些材料进行质量验证4、5、13、14。下面的分析使用0.02 毫克/毫升的浓度。样品浓度适用于使用 dl、紫外-可见光、圆盘离心机、泽塔电位计算和 TEM 分析。
1. Sonicators 对交付功率的校准
注: 有效的声功率传递到声悬挂是一个重要的参数, 以获得可重复的分散。这与制造商指示的发电机的电气输入或输出功率不同, 因为这是在超声26期间可交付给暂停的实际功率。在计算有效交付功率的许多方法中, 最常用的方法是热量分析26。这是一种简单而有效的方法, 用于直接测量传递到悬挂7的有效功率。在此方法中, 在给定的 sonicator 设置中, 液体的温度随时间记录, 并使用以下等式计算出有效的功率: <img alt="Equation" src="/files/ftp_upload/56074/56074eq1.jpg"> 凡 P 为所交付的声波功率 (W), t 是温度 (K), t 对应于时间 (s), Cp是液体的比热 (4.18 J/亨德尔K 为水), M 是液体的质量 (g)。
<ol><li>
用小瓶高音超声波探头标定功率 注意: 该方法适用于 Taurozzi et al.7 , 建议使用以下步骤。<ol>
<li>将一个空的塑料瓶放在天平上, 并将天平的重量。</li>
		<li>用1.5 毫升的 DI 水 (电阻率 18 MΩ·cm) 填满瓶子, 并用天平记录液体的质量。</li>
		<li>将瓶子放在小瓶高音高亮度部分的六小瓶中的一个孔中, 然后将温度探头浸入一个用钳夹连接到数字温度计。确保探头不触及瓶子的壁, 在液体表面下面大约2厘米。</li>
		<li>设置在24赫和 10 W (振幅调整在 50%) 的小瓶高音设置, 并在连续模式下运行。 注: 此处测试的其他振幅调整值为70%、90% 和100%。</li>
		<li>记录三十年代初5分钟的水温升高, 确保瓶子或设定的位置不移位。</li>
		<li>在电子表格软件中创建温度与时间图, 并使用最小二乘回归法获得曲线的最佳线性拟合。</li>
		<li>获取图的斜率 (即随着时间的推移温度的升高) 并计算使用公式 1传递的功率。重复实验三次, 得到平均值。</li>
		<li>重复步骤 1.1.1-1.1.4 70%、90% 和100% 振幅设置。在色散过程中报告了使用该程序获得的功率值。</li>
	</ol>
</li>
	<li>
超声波镀液对输送功率的标定
	<ol>
<li>将一个空的塑料瓶放在天平上, 并将天平的重量。</li>
		<li>用1.5 毫升的 DI 水 (电阻率 18 MΩ·cm) 填满瓶子, 并用天平记录液体的质量。</li>
		<li>将小瓶放在超声波浴缸中间, 一半浸入水中, 然后用夹子固定。使用夹具将温度探头浸入连接到数字温度计上。确保探头不触及瓶子的壁, 在液体表面下面大约2厘米。</li>
		<li>设置在40赫和 80 W 的超声波浴, 并在连续模式下运行。</li>
		<li>记录三十年代初5分钟的水温升高, 确保瓶子或设定的位置不移位。</li>
		<li>在 excel 中创建一个温度与时间图, 并利用最小二乘回归得到曲线的最佳线性拟合。</li>
		<li>在电子表格软件中获取图形的斜率 (即随着时间的推移温度的升高) 并计算使用公式 1传递的电源。重复实验三次, 得到平均值。在色散过程中, 使用该程序得到的功率值报告。</li>
	</ol>
</li>
</ol>2. 使用装有小瓶高音的超声波探头的水介质中的色散过程
<ol><li>用干净的刮刀将每一个需要的纳米重量2毫克, 放入三干净的玻璃瓶中。将它们标记为小瓶1、2和3。</li>
	<li>取出1毫升的 DI 水, 并沿每个小瓶的墙壁添加。用一个干净的薄玻璃棒做一个厚的浆糊, 然后加入其余的水, 使最后的浓度为0.2 毫克/毫升。在疏水样品的情况下, 执行预使用1毫升的0.5% 卷/卷乙醇和添加 DI 水分, 以弥补所需的最终浓度。</li>
	<li>每瓶用它的盖帽和震动好在水平的圆周运动到 removeany 纳米黏附对小瓶的墙壁。</li>
	<li>将三小瓶装在超声波探头装有一瓶高音扬声器, 并应用在脉冲模式下的第一个超声治疗2分钟 1.1 W (1 s/1 s, 这意味着 1 s 和 1 s 关闭)。这将给温度上升大约4° c 在分散作用。</li>
	<li>取出小瓶 1, 从瓶子的顶部取出合适数量的分, 用 DI 水稀释到0.02 毫克/毫升的浓度。使用一系列免费的技术, 如 dl、TEM、紫外光和电子版 (在4节中讨论), 描述稀释后的分散度、粒度分布、形状、结块和泽塔电位。准确记录测量数据。</li>
	<li>暂停10分钟, 从步骤 2.4, 以允许冷却的样品, 并避免任何突然温度上升的系统。在振幅和脉冲模式相同的设置下, 对小瓶2和3进行第二次超声处理, 4 分钟。取出小瓶 2, 重复步骤 2.5, 并记录的读数后6分钟的超声。</li>
	<li>暂停10分钟, 将第三超声治疗应用到小瓶 3, 再4分钟, 然后按照步骤2.5。记录和文件的测量在10分钟的超声 (讨论在4节)。 注意: 在处理悬浮纳米颗粒时, 必须佩戴实验室大衣、手套和护目镜。在较长的实验中, sonicator 必须放在隔音罩中, 在接近超声波源时必须佩戴高保护耳罩。</li>
</ol>3. 超声波浴法在水介质中的分散过程
<ol><li>每所需的纳米2毫克使用清洁的刮刀在四干净的玻璃瓶和标签为小瓶 4, 5, 6, 和7。</li>
	<li>吸管出几滴 DI 水, 并沿每个小瓶的墙壁添加, 并在清洁薄玻璃棒的帮助下做一个厚浆。然后加入其余的水, 使每瓶最后浓度0.2 毫克/毫升。 注: 在疏水样品的情况下, 使用1毫升的0.5% 卷/卷乙醇进行预, 然后增加 DI 水分, 以弥补所需的最终浓度。</li>
	<li>用它的瓶盖封住每个瓶子, 在水平圆周运动中摇匀, 以除去任何粘在瓶子壁上的纳米。</li>
	<li>将四小瓶放在超声波浴缸中间, 用半浸在水中的瓶子, 在室温下使用 80 W 的第一超声治疗15分钟。这将给温度上升大约3° c 在分散作用。</li>
	<li>从超声波槽中取出药瓶 4, 从瓶顶取出适量的分, 用 DI 水稀释0.02 毫克/毫升的浓度, 并对样品进行尺寸、粒度分布、形状、结块和塔泽的表征。可能使用一系列的免费技术, 如 dl, TEM, 紫外可见和电子 (在4节中讨论)。记录和文件的测量。</li>
	<li>改变超声波浴的水和应用第二超声治疗小瓶 5, 6, 和7为另一个15分钟在相同的设置 (80 W)。删除小瓶 5, 按照步骤3.5 的描述和文件的读数在30分钟的超声。</li>
	<li>改变超声波浴中的水 (以避免任何进一步的温度上升) 和应用第三超声处理另30分钟到小瓶6和7在相同的设置与水的变化的一个小小暂停再次在 15 min. 去除瓶6并且跟随步骤3.5。记录和文件的测量在1小时的超声。</li>
	<li>再次改变水在超声波浴每15分钟, 并应用第四超声治疗瓶7为另一个小时保持设置恒定。取出小瓶7并按照步骤3.5 进行完整的表征, 并记录在超声2小时的测量。</li>
</ol>4. 不同时间点分散样品的表征
<ol><li>使用 dl 进行大小描述27<ol>
<li>打开 dl 软件。使用马尔文手册中的折射率值创建一个尺寸测量文件, 它可以针对特定的纳米材料 (包括一个标准) 进行个性化。另外, 根据软件要求输入其他数据, 如吸收和粘度值, 以及分散剂类型。</li>
		<li>在实验条件下输入样品, 如2分钟平衡时间, 20 ° c 温度, 试管型为低容积一次性试管, 实验运行在自动模式。新闻文件 |保存 (用所需的名称保存)。</li>
		<li>按 "文件 |打开新的测量 ", 并运行一个 dl 验证测试, 使用标准的乳胶珠, 标称大小为100纳米, 以符合仪器性能<ol>
<li>使用低音量一次性试管。注射1毫升的样品使用注射器或管, 以避免气泡。 注: 使用前用乙醇和 DI 水清洗试管。</li>
			<li>将试管插入机器。单击 "文件测量" 面板中的 "开始" 按钮。请注意, 这将平衡样品2分钟, 并采取测量在20° c。 注意: 如果样品以前存放在冰箱里, 允许他们在使用前达到室温。</li>
			<li>在自动模式下收集至少五测量值, 并通过选择所有测量值并单击顶部面板中的 "平均值", 以测量的平均值来报告大小。将数据导出到 excel 以进行进一步分析。</li>
			<li>将水动力直径报告为 z 平均值, 在 monomodal 分布28的情况下, 该宽度表示 z 平均值的标准偏差。在 Z 平均值和强度加权尺寸分布的平均值之间存在显著的差异, 这是多或团聚的指示, 对强度加权尺寸分布结果的平均值进行了评述示例状态。</li>
			<li>重复步骤4.1.3 以进行新的测量。 注: dl 不是一种适于分析非理想样品的技术。我们所说的样品是高多的非粒子, 广泛的团聚, 沉淀,等等重复的测量可能导致不准确的读数, 由于沉淀/沉淀粒子。在这种情况下, 建议采用其他免费的技术, 如圆盘离心法, 可以用定性的方法来评估色散。</li>
		</ol>
</li>
	</ol></li>
	<li>圆盘离心法的尺寸分布
	<ol>
<li>打开 CPS 软件。选择 "过程定义", 将示例 SOP 名称放在顶部, 并填充样本参数, 例如最小和最大直径、粒子密度、折射率、吸收和球形因子29。<ol>
<li>例如, 对于 ZnO 纳米粒子, 在最小和最大直径的标签中输入0.1 微米和1.0 微米, 分别在粒子密度中输入5.61 克/毫升, 2.1 在折射率部分, 0.001 在粒子吸收, 1 在球形节.</li>
		</ol>
</li>
		<li>根据 PVC 标准的峰值直径0.377 µm, 以1.385 克/毫升的粒子密度填充校准标准细节。还要填入流体参数 (蔗糖, 流体密度为1.04 克/毫升, 流体折射率为 1.35), 并命名并保存程序。</li>
		<li>选择了选定的过程 (SOP 保存在步骤 4.2.1), 并注入第一个梯度水平, 1.6 毫升蔗糖 (24%) 进入孔通过光盘和按 ' 开始 '。 注: 蔗糖的作用是在圆盘内建立密度梯度, 同时以恒定速度旋转。这将根据大小范围自动计算光盘速度。</li>
		<li>等待软件达到自动计算的 RPM (每分钟轮换)。通过注入蔗糖 (8% 低密度和24% 高密度) 的梯度来稳定沉积物, 见表 1), 每次从最高密度开始, 以最低密度溶液结束的1.6 毫升总体积。 注: 在这里, 我们标记8% 蔗糖溶液为低和24% 蔗糖溶液为高。它们混合在以下卷中 (每次总容量1.6 毫升), 然后一个一个地注入到光盘中, 直到形成渐变。<ol>
<li>在此之后, 注入1.0 毫升的十二帽流体, 帮助保持在光盘内的梯度至少6小时. 允许圆盘离心机平衡1小时。</li>
		</ol>
</li>
		<li>选择 "操作分析器" 并引入示例 ID, 然后按 "开始"。注入0.2 毫升的标准与1毫升注射器在光盘和按空格键在同一时间。然后注入0.2 毫升的样本, 并按下空间酒吧在同一时间。等待测量完成, 然后单击下一个示例。</li>
		<li>使用圆盘离心机控制系统软件获取和处理数据。为此, 单击 "检索分发", 然后单击示例名称;这将打开示例的大小分布图。将数据导出到电子表格管理器。</li>
	</ol></li>
	<li>紫外-可见光光谱法研究色散稳定性 注: 紫外-可见光谱通常用于了解悬浮稳定性和聚集性, 通过仔细观察峰值强度、光谱偏斜度、光谱形状以及吸收光谱4中波长漂移的变化。详细步骤如下。<ol>
<li>打开紫外可见分光光度计软件, 然后单击 "频谱扫描"30。</li>
		<li>使用标准石英试管 (半 microrectangular 石英电池100毫米, 190-2700 nm)。使用吸管注入 2-3 毫升的样品。<ol>
<li>使用前, 用50% 硝酸10分钟洗涤试管, 然后用纯净水洗涤三次。然后用丙酮冲洗, 去除过量, 晾干。</li>
		</ol>
</li>
		<li>预设的仪器设置范围为 700 nm 到 200 nm 波长从波长标签通过点击 "仪器" 在软件面板顶部和点击 ' 设置波长 '。</li>
		<li>单击 "基线"。背景用相应的 "空白"即减去每个频谱, 一个试管只填充介质, 在这种情况下是水。 注: 在疏水性样品的情况下, 乙醇的类似比例: 水被用作分散介质。</li>
		<li>通过点击 "仪器", 在每个样品上收集至少三个单独的光谱属性 ", 并在光谱数中输入" 3 "。取平均值进行分析。保存数据并导出数据以进行进一步分析。</li>
	</ol></li>
	<li>使用的电位测量
	<ol>
<li>打开 dl 软件。创建一个齐塔人潜在的测量文件, 可以个性化的特定纳米材料使用的折射率从马尔文手册的价值。输入可插入软件的其他信息例如、吸收、粘度和分散剂类型, 如在 "示例设置" 选项卡中所示. 单击 "文件 |保存 "并保存为所需的名称。</li>
		<li>点击 "文件 |打开新的测量 ", 并使用参考标准 DTS 1235 (齐塔人的潜在标准) 验证仪器性能。这是一个聚苯乙烯乳胶标准在水溶液中的缓冲 pH 值为 9, 有一个泽塔电位为-42 ± 4.2 mV。</li>
		<li>用至少1毫升容量的注射器准备样品。使用一个一次性折叠毛细细胞与电极在每一侧的齐塔人电位测量。仔细地将样品注入毛细血管细胞, 通过毛细血管细胞的一个端口, 检查有没有气泡。<ol>
<li>一旦样品开始从另一端, 插入塞子和删除任何液体, 可能已溢出到电极。用乙醇和 DI 水彻底清洁试管。</li>
		</ol>
</li>
		<li>将折叠的毛细细胞插入机器。平衡为2分钟, 并取得测量在200° c, 除非指定。如果分散样品以前储存在冰箱里, 允许分散样品在使用前达到室温。</li>
		<li>在自动模式下收集至少五测量值, 并报告平均齐塔人的潜在价值。导出数据, 分析17,18 (通常, 在-25 mv 和25毫伏以上的齐塔人潜在值被认为是稳定的), 并在线或离线解释。</li>
	</ol></li>
	<li>用透射电镜进行形态学表征
	<ol>
<li>使用网格 (300 目) 孔碳膜进行样品制备。在一个干净的格子上放一滴分散样品 (大约0.1 毫升, 0.02 毫克/毫升)。</li>
		<li>允许样品在环境条件下风干, 同时保持网格覆盖以防止空气污染。</li>
		<li>用超纯水清洗网格, 除去任何干燥效果, 并接受 TEM 成像。 注: 在网格上添加色散降会增加网格表面颗粒的浓度, 从而导致有吸引力的颗粒力。干燥不均匀会导致工件。一个小冲洗与超纯水消除了这种风险, 有助于统一干燥的网格31。</li>
		<li>以 dm3 的格式获取图像, 稍后使用 TEM 软件对其进行离线检查。 注: 图像可用于推断周围颗粒大小、结构和形状的互补信息。将文件转换为 tiff, 在该参数中可以对形状和大小等属性进行量化。</li>
	</ol></li>
</ol>

<ol>
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作者没有竞争的财务利益。ik 和 EVJ 共同构思了研究与 ik 的设计, 进行了实验, 分析数据, 并准备了手稿。LJE 和 IR 进行了 TEM 成像。SA、传销和 MC 提供了碳纳米管, 其余的合著人在所有阶段对手稿进行了讨论和评论, RT 为稿件的编辑做出了贡献。

这项研究的最终目的是制定一项战略, 以确定最佳的超声条件, 使选定数量的纳米材料在水中分散。本文试图在超声期间仔细记录协议步骤和参数, 以满足以前在评审中确定的差距, 并遵循过去15中提出的建议。通过对每个超声循环后的分散体进行表征, 并检查样品的稳定性和均匀性, 确定最佳分散条件。根据纳米材料的关键物理化学性质的特征变化, 对超声程序和稳定状态的影响进行评估, 由各种分析技术确定: dl、紫外可见光和透射电镜。当前协议是一种适应的方法为纳米材料的分散从过去文学和其他研究项目21,22,37,38,39修改和改进, 以解决关键的差距, 步骤, 并适用于更广泛的纳米材料的类似表面轮廓7。然而, 需要仔细调整他们的超声时间, 强度和类型, 其应用于其他纳米材料。此外, 还需要进一步的工作, 以建立一个相关的超声程序和生物活性的纳米材料。六不同类型的纳米材料分散体的评估和比较, 主要是为了其稳定性, 使用超声波浴和超声波探头装有一个小瓶高音在设定的时间点。为了保持悬浮纯度和任何意外的变化造成的污染, 探头超声在这里避免。在小瓶高音, 瓶子可以保持关闭。这样就消除了样品的任何交叉污染。
sonicators 的校准是一个关键因素, 因为有不同频率、振幅和功率的 sonicators 范围。为了确定有效的声能量传递到悬浮, sonicators 的校准是用量热法进行的。为70% 振幅设置为小瓶高音的声学功率, 以及为100% 超声波浴缸设置计算为 < 1 w (0.75 ± 0.04 w 和0.093 ± 0.04 w, 分别)。然而, 制造商所指示的功率输出的小瓶高音和浴缸 sonicator 分别为 200 w 和 80 w。这表明, 尽管高功率源, 大部分的能量是失去了在空气泡的产生, 只有一个小的部分实际上是交付给分散在处理26。最近的研究强调了空测量控制的重要性, 与 sonicator 在超声8期间更好的色散控制的输入功率相比。该方法似乎有希望的高精密纳米材料的控制分散, 如碳纳米管和建议未来的研究。
研究中使用的每种技术都是基于对所有人都有限制的不同原则。dl 不是一种理想的非悬浮和高度多系统的技术。在这种情况下, 建议使用 dc, 因为高分辨率、准确性和精确度40。DCS 可以完全分离非常窄的大小分布峰值, 其差异仅为3%。TEM 提供的直接视觉图像的纳米粒子, 是一个伟大的工具, 以确定的聚集, 分散, 大小和形状的粒子, 但该技术要求样品干燥, 可能导致工件41。在步骤4.5.3 中, 用超纯水清洗网格可以消除这种现象。
在其他方面, 该方法强调了一些关键步骤, 如协议中使用的小瓶的类型、浸入深度和在超声浴中的瓶子位置以及小瓶高音。系统在搅拌过程中的温度控制是一个重要的参数。建议在超声的情况下, 在超声波浴和脉冲模式下频繁的水变化, 以避免任何热积累, 从而避免任何样品的变化。预步骤的疏水样品, 如氧化锌有助于分散的粒子, 但这可能会导致一些不必要的变化。超声的时间和能量应该足够高, de-agglomerate 粒子, 但不太多, 它打破了粒子。结果表明, 团聚体断裂取决于颗粒类型。
我们的发现强调了有一个详细的色散协议的重要性, 结果表明, 关键的物理化学性质可能会改变在超声过程中, 由诸如 sonicator 类型, 超声持续时间的因素时间和功率输出。结果表明, 在高强度搅拌的情况下, 样品的完整性可能受到损害。结果表明, 碳纳米管对搅拌具有很好的敏感性, 当超声时间和强度发生变化时, 破损极有可能发生。接近最优设置的碳纳米管的色散是在 2-15 分钟的超声波浴, 只有2分钟使用超声波探头。然而, 超声波仍然可能导致一些纳米管缩略, 这是不能准确量化这里。dl 可能不是对碳纳米管进行表征的理想技术, 但它仍然可以提供纳米结构的流体动力学直径, 这一数据可以说明各种样品的长度分布的差异16, 42,43。过去的研究表明, 随着表面活性剂分子在纳米管单层上的吸收, 可以大大增强碳纳米管的色散协议, 从而为超声35的破坏提供了一个障碍,44. 但是, 这不能直接与本议定书相比较, 因为这种情况下不涉及任何表面活性剂。重要的是要注意, 确保长度大小分布的情况下, 碳纳米管是非常重要的, 因为长宽比往往是相关的某些毒理学反应。相比之下, CeO2给出了与碳纳米管不同的结果, 在这种情况下, 使用超声波浴或探针进行长时间的超声, 会导致初生粒子的形成。碳纳米管和 CeO2 的结果之间的差异突出了定制色散协议的重要性例如, 根据起始材料即: 纳米粉末的类型, 优化超声时间和功率输出。每个纳米材料的粉末样品类型不同, 因为在粉末内部会有不同程度的团聚。在某些情况下, de-agglomeration 过程成功地导致了 de-agglomeration 到初级粒子水平, 这在 TEM 图像中出现了其他形状的粒子, 这在超声步之前是不可见的。长时间的超声导致在不同的角度连续断裂氧化铈凝聚从而导致多面粒子。
在商业购买的 Ag 核动力源分散体的水样品的情况下, 我们的发现也强调需要长期稳定和一致性评估。需要确保分散体在使用前已有足够的特征, 特别是在长期贮存的情况下。然而, 纳米材料的货架寿命很短。它们随着时间的推移而老化, 在长期贮存后, 与新制备的分散体相比, 其行为可能有所不同。
这里的结果突出表明, 需要一个统一的战略, 以确定一个优化的协议, 为不同的纳米材料。提出的策略是在超声方法上进行不同的变化, 并确保在不同时间点的分散体使用互补的分析方法进行充分的表征。过去的工作人员45强调了使用多种方法来描述和监测通过时间和不同实验条件的色散质量的重要性。虽然在研究中提出了各种超声的方法来迎合特定的纳米材料的分散性, 但它们有可能被用作在水中分散其他金属和金属氧化物 (类似的表面性质) 的基础。然而, 无论是在纳米材料类型或液体介质的任何变化, 需要优化的基本协议, 可以通过仔细调整各种因素例如, 超声时间, 强度和 sonicator 类型。无论选择什么协议, 并确定为最佳, 总是需要有一个详细的报告的方案和逐步序列的超声分散程序。这对提高解释和可比性很重要。该协议的一个应用是促进其他实验室之间的数据可比性, 从而为将来的研究提供统一和标准化的方法。现有的方法和控制参数可用于除水之外的其他分散介质, 并可根据案例进行比较。

超声是生成蚀的过程, 它涉及在液体中形成的气泡 (通常称为热点) 的产生、生长和坍塌, 这是由于高强度超声1的照射。在实验室设置中, 采用超声方法进行 sonicator。有不同的 sonicators, 都具有 de-agglomerating 粒子的一般功能, 在液体介质中作为单个 (或主要) 粒子分散。通过应用超声, 样品均匀性可以改善, 可能达到更窄的粒度分布。在色散过程中要考虑的一个重要方面是最终色散的稳定性。在这里, 悬浮物的稳定性被定义为粒子在其分散状态下不沉淀或沉淀下来的地方, 并且平均水动力直径测量在那期间被采取的五多次测量之间不变化超过10%时间 (大约10分钟)2,3。有几种方法来测量色散稳定性。这包括通过测量粒子的电泳移动性来估计泽塔电位 (ZP)。另一种方法是测量纳米粒子在紫外光谱范围内的吸收特性4。
在理学领域, 控制分散质量的能力非常重要, 因为分散步骤将决定关键的物理化学性质, 如粒度/粒径分布、形状、聚合/团聚、表面电荷,等这反过来最终会影响粒子与测试介质的相互作用以及各种体外和体内实验的结果, 以推断纳米材料的潜在危害。
超声通常是通过使用探针型 (直接) 或超声波浴, 或超声波探头与小瓶高音 (间接超声) 进行的。所有类型的超声都可在强度和输出功率设置, 有时适应不同类型的 sonotrode 为特定的过程或要求, 并适用于液体量范围从2至250毫升。虽然探针超声波是已知的表现优于浴超声由于高度本地化强度5, 浴缸超声往往是首选超过探头型的准备毒理学试验悬浮, 因为可能通过尖端的污染风险, 钛探针在长时间使用后的侵蚀, 以及探头浸入深度的差异。同样, 装有小瓶高音的超声波探头在直接探头上是有利的, 因为 above-mentioned 污染的风险以及设备的操作友好性。几个小瓶是声在同一时间, 并在相同的强度。这不仅节省了时间, 而且确保所有的样品都得到同等对待, 从而使样品中的结果更加可靠和可比。在纳米材料的安全研究中, 污染总是被避免的。但是, 探测器 sonicator 不符合此要求, 并且尚未进行测试。探针 sonicators 是已知的造成一些不可避免的副作用, 例如由于尖端侵蚀的样品污染, 以及减少能量输出导致的分散条件的变化, 从而损害数据再现性6,7,8. 此外, 样品通常在未发现的容器中运行, 导致蒸发和尘埃沉积造成液体损失。为了避免这些意外的改变, 最近的研究推荐了基于其有效能量传递的替代性间接 sonicators 以及悬浮纯度保证6。
非优化超声会对结果产生不利影响。它可能会改变纳米材料的主要物理和化学性质, 如大小、大小分布、形貌和表面电荷2,9。以前的文献报道过这样的缺陷, 控制超声过程和对粒子参数的影响, 如纳米的25,10,11, 纳米氧化锌6, 和纳米铜12.此外, 过去的研究表明, 超声过程不仅改变了粒子特性, 而且还控制了毒理学测试的结果12,13。
要控制分散过程, 重要的是要监测和了解不同的因素, 如 sonicator 类型, 仪器电源和持续时间, 体积,等, 可能会影响分散质量。因此, 需要有一个系统的程序, 以分析的关键物理化学特性的颗粒在分散在不同时间点的超声过程。虽然一些研究人员已经考虑到这种考虑, 但这方面的工作是有限的。比哈尔et al.研究了不同的超声能量和不同色散稳定器的纳米材料的分散稳定性14。Hartmannn et al.最近进行的一项审查强调指出, 虽然已经做了一些工作来了解影响纳米材料色散质量的不同因素例如、使用的 sonicator 类型、超声时间、等等, 但仍然没有目前支持 nanotoxicological 测试和调查的超声程序定义良好且普遍接受的过程7,15。
利用几种分析表征技术对分散质量进行监测。这些措施包括: 动态光散射 (dl)、圆盘离心、电泳光散射 (波段)、紫外可见光 (紫外可见光) 光谱学和透射电子显微镜 (TEM), 它测量颗粒大小/大小分布,分别为泽塔电位、色散稳定性和形态学特征。dl 通常用于确定纳米材料分散体的水动力直径 (Z 平均) 和多指数。在多模态粒度分布的情况下, Z 平均值可能与强度加权尺寸分布强度不一致。因此, 可以引用强度加权大小分布的平均值。它反映了规模分布的广度, 范围从 0-1, 0 是分散样本, 1 是高度多样本16。圆盘离心法是一种分离技术, 用于测定液体介质中离心沉淀法的粒度分布。粒子在光学上清晰和旋转的圆盘内沉积, 当粒子到达圆盘边缘时散射的光量被记录并转化为粒子大小分布, 使用斯托克斯定律。为了解决多模态颗粒分布的问题, 圆盘离心机的技术更合适, 因为它们在仪器中集成了分离机构元件。粒子的电位 (ζ-电位) 被定义为在其剪切或滑动平面上的电势, 这是在电双层内的一个概念边界, 它将 (散装) 液体显示出正常的粘性行为。船尾层, 主要由反离子组成的层, 被认为与粒子一起移动。泽塔电位直接与粒子的表面电荷有关, 因此与粒子之间的静电相互作用 (即、斥力/引力) 有关。因此, 该参数被认为是纳米材料分散稳定性的主要指标。根据惯例, 在-25 mv 和 25 mv 以上的齐塔人的潜在价值被认为是稳定的17,18。离子的集中和类型并且解答 pH 值强烈影响泽塔潜在的19。用于测量色散中粒子的电泳迁移率, 通过亨利方程和 Smoluchowski 或休克模型将这种移动性转化为泽塔电位。紫外-可见光光谱学是一种技术, 用来量化的光被吸收和分散的样品在特定的波长。它经常被用来通过测量纳米材料在紫外区域的特性吸收来监测色散的稳定性。最后, TEM 经常用于可视化和分析纳米粒子的大小、大小分布、团聚和形状5、14、15、20。
我们提出了六种不同的纳米材料分散体使用超声波浴和超声波探头装有一个小瓶高音的对比研究。研究中使用的粒子浓度、温度、sonicator 类型和设置在协议中指定, 因此可以推断类似探针和超声波浴的实验设置。下列纳米材料被使用: 银 (Ag), 氧化铈 (CeO2), 氧化锌 (氧化锌, NM110-hydrophylic 和 NM111-hydrophobic), 和碳纳米管 (A32 和 A106, 参见材料表)。
利用各种表征技术对超声过程中不同时间点的色散质量进行了评估, 即粒度/粒径分布的 dl、尺寸分布的圆盘离心、泽塔电位的测试紫外-可见光谱的稳定性, 和 TEM 的颗粒形状和均匀性。评估了许多不同的纳米材料, 从金属氧化物到碳基。为比较, 商业水悬浮的银纳米粒子 (Ag NPs) 稳定与柠檬酸盖是并行使用, 以推断预期的长期稳定的相关商业可用悬架。显然, 这种 Ag NPs 模型与任何分散程序没有直接关系, 只是表明需要在储存一段时间后 re-sonicate 或 re-stabilize 悬浮液, 如 re-agglomeration 的变化必然发生在存储.悬挂在冰箱里保存了两个月。在此期间, 色散的特点是识别潜在的颗粒团聚。初始结果显示不稳定的挂起 (如 "结果" 部分中所述)。随后, 这种分散进一步受到不同的超声处理, 类似于研究中使用的其他纳米材料。研究的目的是确认我们可以通过相同的超声协议 de-agglomerate 中止。因此, Ag NPs 模型可以作为长期研究的基准, 代表再粒子的优化形式。
这里提供的色散协议与以前的文献中所发表的相似之处相同, 并且包含了以前的工作人员所做过的一些建议7,21,22,23 ,24,25。在本研究中, 系统和逐步的方法是用来监测分散质量在整个色散协议。这种方法进行纳米材料分散体的 real-time 表征, 以确定最佳的实验色散条件 (图 1)。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56074/56074fig1.jpg"> 图1。描述色散协议的方案和逐步序列的流程图.<a href="//cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56074/56074fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

<table border="0" cellpadding="0" cellspacing="0" width="906">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Cerium oxide nanopowder</td>
			<td style="width:305px;">Sigma-Aldrich</td>
			<td style="width:119px;">544841</td>
			<td style="width:280px;">&#60;25&#160;nm particle size (BET)</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;">Zinc oxide</td>
			<td style="width:305px;">European Commission&#39;s Joint Research Centre (JRC)</td>
			<td style="width:119px;">NM110</td>
			<td>hydrophylic</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;">Zinc oxide</td>
			<td style="width:305px;">European Commission&#39;s Joint Research Centre (JRC)</td>
			<td style="width:119px;">NM111</td>
			<td>hydrophobic</td>
		</tr>
		<tr height="85">
			<td height="85" style="height:85px;width:203px;">Multi walled carbon nanotubes</td>
			<td style="width:305px;">NanoMile project (Large Collaborative Project under the European Commission&#39;s 7th Framework Programme)</td>
			<td style="width:119px;">A32 (MWCNT1)</td>
			<td>3.0&#177;1.8 &#181;m long, O/C ratio of 4.5%</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:203px;">Multi walledcarbon nanotubes</td>
			<td style="width:305px;">NanoMile project</td>
			<td style="width:119px;">A106 (MWCNT2)</td>
			<td>3.3&#177;2.4 &#181;m long, O/C ratio of 7%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Silver dispersion</td>
			<td style="width:305px;">Sigma-Aldrich</td>
			<td style="width:119px;">730785</td>
			<td>10&#160;nm particle size (TEM), 0.02&#160;mg/mL</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:203px;">Zetasizer nano</td>
			<td style="width:305px;">Malvern Instruments</td>
			<td style="width:119px;"></td>
			<td>Particle size and zeta-potential measurements&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Disc Centrifuge</td>
			<td>CPS instruments Inc.</td>
			<td>Model DC 24000</td>
			<td>Particle size distribution by centrifugal sedimentation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Transmission electron microscope</td>
			<td style="width:305px;">JEOL USA</td>
			<td style="width:119px;">Jeol 1200EX TEM</td>
			<td>Bright field images, particle size, shape, agglomeration</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ultrasonic probe fitted with a vial tweeter</td>
			<td style="width:305px;">Hielscher</td>
			<td>UIS250V</td>
			<td>Sonicator</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Ultrasonic bath</td>
			<td>Branson&#160;</td>
			<td style="width:119px;">Model 1510</td>
			<td>Sonicator</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Eppendorf vials</td>
			<td style="width:305px;">Eppendorf</td>
			<td style="width:119px;">2236411-1</td>
			<td>1.5ml capacity</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:203px;">UV-vis spectrophotometer</td>
			<td style="width:305px;">Jenson flight deck</td>
			<td style="width:119px;">Model 6800</td>
			<td>SPR peaks, suspension stability</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:203px;">Disposable folded capillary cell</td>
			<td style="width:305px;">Malvern Instruments</td>
			<td>DTS 1070</td>
			<td>for the measurement of elecr</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Zeta- potential standard</td>
			<td style="width:305px;">Malvern Instruments</td>
			<td style="width:119px;">DTS 1235</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Quartz cuvette</td>
			<td style="width:305px;">Jasco</td>
			<td>1103-0042</td>
			<td>Rectangular quartz cell 10 x 100 
			Spectrosil Quartz with lid 190 -2700 nm</td>
		</tr>
	</tbody>
</table>

dispersion of nanomaterials in aqueous media: towards protocol optimization

超声过程通常用于水基介质中的 de-agglomerating 和分散纳米材料, 这对提高悬浮液的均匀性和稳定性是必要的。在本研究中, 采用系统的逐步方法来确定最佳的超声条件, 以达到稳定的色散。这种方法已被采用, 并表明适用于一些纳米材料 (氧化铈, 氧化锌, 碳纳米管) 分散在去离子 (DI) 水中。然而, 无论是纳米材料的类型还是分散介质的变化, 都需要通过调整超声时间、功率和 sonicator 类型以及升温过程中的温度升高等各种因素来优化基本协议。该方法详细记录了色散过程。这是必要的, 以确定的时间点以及其他 above-mentioned 的条件, 在超声过程中可能会有不可取的变化, 如损害的粒子表面, 从而影响表面属性。我们的目标是提供一种协调的方法, 可以控制最终产生的分散的质量。这一准则有助于确保纳米社区, 特别是理学领域的分散质量重复性。

Watch this Scientific Journal Video about Dispersion of Nanomaterials in Aqueous Media: Towards Protocol Optimization at JoVE.com

Dispersion of Nanomaterials in Aqueous Media: Towards Protocol Optimization

在这里, 我们提出了逐步协议的纳米材料在水介质中的分散性 real-time 表征, 以确定最佳超声条件, 强度和持续时间, 以提高稳定性和均匀性纳米颗粒不影响样品完整性的分散体。

纳米材料在水介质中的分散: 对协议优化的研究

The sonication process is commonly used for de-agglomerating and dispersing nanomaterials in aqueous based media, necessary to improve homogeneity and ...

dispersion-nanomaterials-aqueous-media-towards-protocol

Nanyang Technological University

Research

JoVE Journal

Environment

28.2K 次观看.  University of Birmingham. 在这里, 我们提出了逐步协议的纳米材料在水介质中的分散性 real-time 表征, 以确定最佳超声条件, 强度和持续时间, 以提高稳定性和均匀性纳米颗粒不影响样品完整性的分散体。

视频: Dispersion of Nanomaterials in Aqueous Media: Towards Protocol Optimization

Experimental Protocol for Manipulating Plant-induced Soil Heterogeneity

Coexistence theory has often treated environmental heterogeneity as being independent of the community composition; however biotic feedbacks such as plant-soil feedbacks (PSF) have large effects on plant performance, and create environmental heterogeneity that depends on the community composition. Understanding the importance of PSF for plant community assembly necessitates understanding of the role of heterogeneity in PSF, in addition to mean PSF effects. Here, we describe a protocol for manipulating plant-induced soil heterogeneity. Two example experiments are presented: (1) a field experiment with a 6-patch grid of soils to measure plant population responses and (2) a greenhouse experiment with 2-patch soils to measure individual plant responses. Soils can be collected from the zone of root influence (soils from the rhizosphere and directly adjacent to the rhizosphere) of plants in the field from conspecific and heterospecific plant species. Replicate collections are used to avoid pseudoreplicating soil samples. These soils are then placed into separate patches for heterogeneous treatments or mixed for a homogenized treatment. Care should be taken to ensure that heterogeneous and homogenized treatments experience the same degree of soil disturbance. Plants can then be placed in these soil treatments to determine the effect of plant-induced soil heterogeneity on plant performance. We demonstrate that plant-induced heterogeneity results in different outcomes than predicted by traditional coexistence models, perhaps because of the dynamic nature of these feedbacks. Theory that incorporates environmental heterogeneity influenced by the assembling community and additional empirical work is needed to determine when heterogeneity intrinsic to the assembling community will result in different assembly outcomes compared with heterogeneity extrinsic to the community composition.

Understanding the role of environmental heterogeneity in species coexistence has typically focused on types of heterogeneity that are extrinsic to the community&#8217;s species composition. We provide novel detailed methods for creating soil heterogeneity treatments using soils subject to plant-soil feedback conditioning, or heterogeneity intrinsic to the community composition.

用于操纵植物诱导土壤异质性的实验协议

Coexistence theory has often treated environmental heterogeneity as being independent of the community composition; however biotic feedbacks such as ...

科研

环境科学

A Protocol for Conducting Rainfall Simulation to Study Soil Runoff

Rainfall is a driving force for the transport of environmental contaminants from agricultural soils to surficial water bodies via surface runoff. The objective of this study was to characterize the effects of antecedent soil moisture content on the fate and transport of surface applied commercial urea, a common form of nitrogen (N) fertilizer, following a rainfall event that occurs within 24&#160;hr&#160;after fertilizer application. Although urea is assumed to be readily hydrolyzed to ammonium and therefore not often available for transport, recent studies suggest that urea can be transported from agricultural soils to coastal waters where it is implicated in harmful algal blooms. A rainfall simulator was used to apply a consistent rate of uniform rainfall across packed soil boxes that had been prewetted to different soil moisture contents. By controlling rainfall and soil physical characteristics, the effects of antecedent soil moisture on urea loss were isolated. Wetter soils exhibited shorter time from rainfall initiation to runoff initiation, greater total volume of runoff, higher urea concentrations in runoff, and greater mass loadings of urea in runoff. These results also demonstrate the importance of controlling for antecedent soil moisture content in studies designed to isolate other variables, such as soil physical or chemical characteristics, slope, soil cover, management, or rainfall characteristics. Because rainfall simulators are designed to deliver raindrops of similar size and velocity as natural rainfall, studies conducted under a standardized protocol can yield valuable data that, in turn, can be used to develop models for predicting the fate and transport of pollutants in runoff.

A rainfall simulator was used to apply a consistent rate of uniform rainfall to packed soil boxes in a study of the fate and transport of urea, a nonpoint source environmental contaminant. Under uniform soil and rainfall conditions, antecedent soil moisture content exerted strong control over urea loss in surface runoff.

一个协议，用于开展降雨模拟研究土壤径流

Rainfall is a driving force for the transport of environmental contaminants from agricultural soils to surficial water bodies via surface runoff. The ...

Modifying the Bank Erosion Hazard Index (BEHI) Protocol for Rapid Assessment of Streambank Erosion in Northeastern Ohio

Understanding the source of pollution in a stream is vital to preserving, restoring, and maintaining the stream&#8217;s function and habitat it provides. Sediments from highly eroding streambanks are a major source of pollution in a stream system and have the potential to jeopardize habitat, infrastructure, and stream function. Watershed management practices throughout the Cleveland Metroparks attempt to locate and inventory the source and rate the risk of potential streambank erosion to assist in formulating effect stream, riparian, and habitat management recommendations. The Bank Erosion Hazard Index (BEHI), developed by David Rosgen of Wildland Hydrology is a fluvial geomorphic assessment procedure used to evaluate the susceptibility of potential streambank erosion based on a combination of several variables that are sensitive to various processes of erosion. This protocol can be time consuming, difficult for non-professionals, and confined to specific geomorphic regions. To address these constraints and assist in maintaining consistency and reducing user bias, modifications to this protocol include a &#8220;Pre-Screening Questionnaire&#8221;, elimination of the Study Bank-Height Ratio metric including the bankfull determination, and an adjusted scoring system. This modified protocol was used to assess several high priority streams within the Cleveland Metroparks. The original BEHI protocol was also used to confirm the results of the modified BEHI protocol. After using the modified assessment in the field, and comparing it to the original BEHI method, the two were found to produce comparable BEHI ratings of the streambanks, while significantly reducing the amount of time and resources needed to complete the modified protocol.

Modifying the Bank Erosion Hazard Index BEHI Protocol for Rapid Assessment of Streambank Erosion in Northeastern Ohio

Streambank erosion potential can be evaluated and ranked using David Rosgen&#8217;s Bank Erosion Hazard Index (BEHI), however this protocol has significant limitations. Here we present protocol modifications to address time constraints, allow nonprofessionals to complete accurate assessments, and account for non-alluvial stream conditions in Northeast Ohio.

修改银行侵蚀危险指数（BEHI）协议的河岸侵蚀美国俄亥俄州东北部的快速评估

Understanding the source of pollution in a stream is vital to preserving, restoring, and maintaining the stream&#8217;s function and habitat it provides. ...

Experimental Protocol for Detecting Cyanobacteria in Liquid and Solid Samples with an Antibody Microarray Chip

Global warming and eutrophication make some aquatic ecosystems behave as true bioreactors that trigger rapid and massive cyanobacterial growth; this has relevant health and economic consequences. Many cyanobacterial strains are toxin producers, and only a few cells are necessary to induce irreparable damage to the environment. Therefore, water-body authorities and administrations require rapid and efficient early-warning systems providing reliable data to support their preventive or curative decisions. This manuscript reports an experimental protocol for the in-field detection of toxin-producing cyanobacterial strains by using an antibody microarray chip with 17 antibodies (Abs) with taxonomic resolution (CYANOCHIP). Here, a multiplex fluorescent sandwich microarray immunoassay (FSMI) for the simultaneous monitoring of 17 cyanobacterial strains frequently found blooming in freshwater ecosystems, some of them toxin producers, is described. A microarray with multiple identical replicates (up to 24) of the CYANOCHIP was printed onto a single microscope slide to simultaneously test a similar number of samples. Liquid samples can be tested either by direct incubation with the antibodies (Abs) or after cell concentration by filtration through a 1- to 3-&#956;m filter. Solid samples, such as sediments and ground rocks, are first homogenized and dispersed by a hand-held ultrasonicator in an incubation buffer. They are then filtered (5 - 20 &#956;m) to remove the coarse material, and the filtrate is incubated with Abs. Immunoreactions are revealed by a final incubation with a mixture of the 17 fluorescence-labeled Abs and are read by a portable fluorescence detector. The whole process takes around 3 h, most of it corresponding to two 1-h periods of incubation. The output is an image, where bright spots correspond to the positive detection of cyanobacterial markers.

Experimental Protocol for Detecting Cyanobacteria in Liquid and Solid Samples with an Antibody Microarray Chip

The presence of cyanobacterial toxins in fresh water reservoirs for human consumption is a major concern for water management authorities. To evaluate the risk of water contamination, this article describes an protocol for the in-field detection of cyanobacterial strains in liquid and solid samples by using an antibody microarray chip.

用于检测实验方案<em&gt;蓝藻</em&gt;与抗体基因芯片液体和固体样品

Global warming and eutrophication make some aquatic ecosystems behave as true bioreactors that trigger rapid and massive cyanobacterial growth; this has ...

Video Tracking Protocol to Screen Deterrent Chemistries for Honey Bees

The European honey bee, Apis mellifera L., is an economically and agriculturally important pollinator that generates billions of dollars annually. Honey bee colony numbers have been declining in the United States and many European countries since 1947. A number of factors play a role in this decline, including the unintentional exposure of honey bees to pesticides. The development of new methods and regulations are warranted to reduce pesticide exposures to these pollinators. One approach is the use of repellent chemistries that deter honey bees from a recently pesticide-treated crop. Here, we describe a protocol to discern the deterrence of honey bees exposed to select repellent chemistries. Honey bee foragers are collected and starved overnight in an incubator 15 h prior to testing. Individual honey bees are placed into Petri dishes that have either a sugar-agarose cube (control treatment) or sugar-agarose-compound cube (repellent treatment) placed into the middle of the dish. The Petri dish serves as the arena that is placed under a camera in a light box to record the honey bee locomotor activities using video tracking software. A total of 8 control and 8 repellent treatments were analyzed for a 10 min period with each treatment was duplicated with new honey bees. Here, we demonstrate that honey bees are deterred from the sugar-agarose cubes with a compound treatment whereas honey bees are attracted to the sugar-agarose cubes without an added compound.

The loss of honey bee colonies presents a challenge to crop pollination services. Current pollinator protection practices warrant an alternative approach to minimize the contact of honey bees to harmful pesticides using repellent chemistries. Here, we provide detailed methods for a visual tracking protocol to screen deterrents for bees.

用于蜂蜜蜜蜂筛选化学成分的视频跟踪协议

The European honey bee, Apis mellifera L., is an economically and agriculturally important pollinator that generates billions of dollars annually. Honey ...

Functionalization and Dispersion of Carbon Nanomaterials Using an Environmentally Friendly Ultrasonicated Ozonolysis Process

Functionalization of carbon nanomaterials is often a critical step that facilitates their integration into larger material systems and devices. In the as-received form, carbon nanomaterials, such as carbon nanotubes (CNTs) or graphene nanoplatelets (GNPs), may contain large agglomerates. Both agglomerates and impurities will diminish the benefits of the unique electrical and mechanical properties offered when CNTs or GNPs are incorporated into polymers or composite material systems. Whilst a variety of methods exist to functionalize carbon nanomaterials and to create stable dispersions, many the processes use harsh chemicals, organic solvents, or surfactants, which are environmentally unfriendly and may increase the processing burden when isolating the nanomaterials for subsequent use. The current research details the use of an alternative, environmentally friendly technique for functionalizing CNTs and GNPs. It produces stable, aqueous dispersions free of harmful chemicals. Both CNTs and GNPs can be added to water at concentrations up to 5 g/L and can be recirculated through a high-powered ultrasonic cell. The simultaneous injection of ozone into the cell progressively oxidizes the carbon nanomaterials, and the combined ultrasonication breaks down agglomerates and immediately exposes fresh material for functionalization. The prepared dispersions are ideally suited for the deposition of thin films onto solid substrates using electrophoretic deposition (EPD). CNTs and GNPs from the aqueous dispersions can be readily used to coat carbon- and glass-reinforcing fibers using EPD for the preparation of hierarchical composite materials.

Here, a novel method for the functionalization and stable dispersion of carbon nanomaterials in aqueous environments is described. Ozone is injected directly into an aqueous dispersion of carbon nanomaterial that is continuously recirculated through a high-powered ultrasonic cell.

碳纳米材料的功能化和分散使用环境友好的超声波臭氧分解过程

Functionalization of carbon nanomaterials is often a critical step that facilitates their integration into larger material systems and devices. In the ...

Microfluidic Devices for Characterizing Pore-scale Event Processes in Porous Media for Oil Recovery Applications

Microfluidic devices are versatile tools for studying transport processes at a microscopic scale. A demand exists for microfluidic devices that are resistant to low molecular-weight oil components, unlike traditional polydimethylsiloxane (PDMS) devices. Here, we demonstrate a facile method for making a device with this property, and we use the product of this protocol for examining the pore-scale mechanisms by which foam recovers crude oil. A pattern is first designed using computer-aided design (CAD) software and printed on a transparency with a high-resolution printer. This pattern is then transferred to a photoresist via a lithography procedure. PDMS is cast on the pattern, cured in an oven, and removed to obtain a mold. A thiol-ene crosslinking polymer, commonly used as an optical adhesive (OA), is then poured onto the mold and cured under UV light. The PDMS mold is peeled away from the optical adhesive cast. A glass substrate is then prepared, and the two halves of the device are bonded together. Optical adhesive-based devices are more robust than traditional PDMS microfluidic devices. The epoxy structure is resistant to swelling by many organic solvents, which opens new possibilities for experiments involving light organic liquids. Additionally, the surface wettability behavior of these devices is more stable than that of PDMS. The construction of optical adhesive microfluidic devices is simple, yet requires incrementally more effort than the making of PDMS-based devices. Also, though optical adhesive devices are stable in organic liquids, they may exhibit reduced bond-strength after a long time. Optical adhesive microfluidic devices can be made in geometries that act as 2-D micromodels for porous media. These devices are applied in the study of oil displacement to improve our understanding of the pore-scale mechanisms involved in enhanced oil recovery and aquifer remediation.

The goal of this procedure is to easily and rapidly produce a microfluidic device with customizable geometry and resistance to swelling by organic fluids for oil recovery studies. A polydimethylsiloxane mold is first generated, and then used to cast the epoxy-based device. A representative displacement study is reported.

微流体器件用于表征多孔介质中的孔隙尺度事件过程, 用于采油应用

Microfluidic devices are versatile tools for studying transport processes at a microscopic scale. A demand exists for microfluidic devices that are ...

Resurrection of Dormant Daphnia magna: Protocol and Applications

Long-term studies enable the identification of eco-evolutionary processes that occur over extended time periods. In addition, they provide key empirical data that may be used in predictive modelling to forecast evolutionary responses of natural ecosystems to future environmental changes. However, excluding a few exceptional cases, long-term studies are scarce because of logistic difficulties associated with accessing temporal samples. Temporal dynamics are frequently studied in the laboratory or in controlled mesocosm experiments with exceptional studies that reconstruct the evolution of natural populations in the wild.
Here, a standard operating procedure (SOP) is provided to revive or resurrect dormant Daphnia magna, a widespread zooplankton keystone species in aquatic ecosystems, to dramatically advance the state-of-the-art longitudinal data collection in natural systems. The field of Resurrection Ecology was defined in 1999 by Kerfoot and co-workers, even though the first attempts at hatching diapausing zooplankton eggs date back to the late 1980s. Since Kerfoot&#39;s seminal paper, the methodology of resurrecting zooplankton species has been increasingly frequently applied, though propagated among laboratories only via direct knowledge transfer. Here, an SOP is described that provides a step-by-step protocol on the practice of resurrecting dormant Daphnia magna eggs.
Two key studies are provided in which the fitness response of resurrected Daphnia magna populations to warming is measured, capitalizing on the ability to study historical and modern populations in the same settings. Finally, the application of next generation sequencing technologies to revived or still dormant stages is discussed. These technologies provide unprecedented power in dissecting the processes and mechanisms of evolution if applied to populations that have experienced changes in selection pressure over time.

Resurrection of Dormant Daphnia magna: Protocol and Applications

Long-term studies are essential to understanding the process of evolution and the mechanisms of adaptation. Generally, these studies require commitments beyond the life-time of researchers. Here, a powerful method is described that dramatically advances state-of-the-art data collection to generate longitudinal data in natural systems.

休眠蚤的复活: 协议和应用

Long-term studies enable the identification of eco-evolutionary processes that occur over extended time periods. In addition, they provide key empirical ...

Experimental Protocol for Detecting Mitochondrial Function in Hepatocytes Exposed to Organochlorine Pesticides

This paper presents detailed methods on detecting hepatic mitochondrial function for a better understanding the cause of metabolic disorders caused by environmental organochlorine pesticides (OCPs) in hepatocytes. HepG2 cells were exposed to &#946;-hexachlorocyclohexane (&#946;-HCH) for 24 h at an equivalent dose of internal exposure in general population. Ultrastructure in hepatocytes was examined by transmission electron microscopy (TEM) to show the damage of mitochondria. Mitochondrial function was further evaluated by mitochondrial fluorescence intensity, adenosine 5'-triphosphate (ATP) levels, oxygen consumption rate (OCR) and mitochondrial membrane potential (MMP) in HepG2 cells incubated with &#946;-HCH. The mitochondria fluorescence intensity after stained by mitochondrial green fluorescent probe was observed with a fluorescence microscopy. The luciferin-luciferase reaction was used to determine ATP levels. The MMP was detected by the cationic dye JC-1 and analyzed under flow cytometry. OCR was measured with an extracellular flux analyzer. In summary, these protocols were used in detecting mitochondrial function in hepatocytes with to investigate mitochondria damages.

Understanding the influence of environmental organochlorine pesticides (OCPs) on mitochondrial function in hepatocytes is important in exploring the mechanism of OCPs causing metabolic disorders. This paper presents detailed methods on detecting hepatic mitochondrial function.

检测暴露于有机氯农药的肝细胞线粒体功能的实验方案

This paper presents detailed methods on detecting hepatic mitochondrial function for a better understanding the cause of metabolic disorders caused by ...

Metal Corrosion and the Efficiency of Corrosion Inhibitors in Less Conductive Media

Material corrosion can be a limiting factor for different materials in many applications. Thus, it is necessary to better understand corrosion processes, prevent them and minimize the damages associated with them. One of the most important characteristics of corrosion processes is the corrosion rate. The measurement of corrosion rates is often very difficult or even impossible especially in less conductive, non-aqueous environments such as biofuels. Here, we present five different methods for the determination of corrosion rates and the efficiency of anti-corrosion protection in biofuels: (i) a static test, (ii) a dynamic test, (iii) a static test with a reflux cooler and electrochemical measurements (iv) in a two-electrode arrangement and (v) in a three-electrode arrangement. The static test is advantageous due to its low demands on material and instrumental equipment. The dynamic test allows for the testing of corrosion rates of metallic materials at more severe conditions. The static test with a reflux cooler allows for the testing in environments with higher viscosity (e.g., engine oils) at higher temperatures in the presence of oxidation or an inert atmosphere. The electrochemical measurements provide a more comprehensive view on corrosion processes. The presented cell geometries and arrangements (the two-electrode and three-electrode systems) make it possible to perform measurements in biofuel environments without base electrolytes that could have a negative impact on the results and load them with measurement errors. The presented methods make it possible to study the corrosion aggressiveness of an environment, the corrosion resistance of metallic materials, and the efficiency of corrosion inhibitors with representative and reproducible results. The results obtained using these methods can help to understand corrosion processes in more detail to minimize the damages caused by corrosion.

The testing of processes associated with material corrosion can often be difficult especially in non-aqueous environments. Here, we present different methods for short-term and long-term testing of corrosion behavior of non-aqueous environments such as biofuels, especially those containing bioethanol.

金属腐蚀与腐蚀抑制剂在低导电介质中的效率

Material corrosion can be a limiting factor for different materials in many applications. Thus, it is necessary to better understand corrosion processes, ...