作者希望感谢两位匿名的同行评论家和朱庇特高级审查编辑艾丽莎 DSouza 博士的宝贵意见。这项研究是在阿贡国家实验室的高级光子源 (APS) 的 6-BM B 上进行的。这一设施的使用得到了地球科学 (COMPRES) 的材料属性研究财团的支持, 根据国家科学基金会 (NSF) 合作协议耳 11-57758, 耳1661511和由矿物物理学院, 石溪大学。作者通过耳1361463、耳1045629和耳1141895来确认这个项目的研究资金的 NSF。这项研究使用了先进的光子源资源, 美国能源部 (能源部) 科学用户设施办公室为能源部的科学办公室由阿贡国家实验室根据合同 DEAC02-06CH11357。单元组件在 COMPRES 多砧单元组件开发项目下。所有的数据文件都可以根据要求提交 (scheung9@wisc.edu scheung9@wisc。样品和数据被归档在矿物物理学院在石溪大学。

1. 样品准备
<ol><li>选择测试和/或参考样品;这可以是岩石核心 (步骤 1.2) 或矿物骨料 (步骤 1.3), 这取决于实验研究的重点。 注意: 下面的方法肯定不是准备好质量示例的唯一方法 (例如,其他机器可以使用)。然而, 本研究所采用的样品制备方法, 充分说明了实现准确复制的目的。</li>
	<li>
岩芯样品
	<ol>
<li>从一个较大的样品岩石块看到一个小矩形板。然后表面研磨的样品板, 使所有六表面的板是平坦的, 垂直于其相邻的表面。</li>
		<li>为了最小化在核心钻探过程中试样板的任何移动, 请在高度稳定的工作表面放置机器副 (图 2a) 开始。确保所有接触面都是干净的, 以便不将非垂直度引入到安装程序中。将样本板置于副颚 (图 2a) 之间, 并拧紧这些颚, 确保它们只是足够紧密, 以确保样品不损坏它。</li>
		<li>使用旋转工作站包作为取心钻床安装旋转工具 (图 2a)。将2毫米 (内径) 取心金刚石钻头插入钻孔机的可调卡盘中。螺丝和锁芯钻头, 以确保装配在钻探过程中是稳定的。</li>
		<li>打开旋转工具, 开始将钻具装配到试样板上。 注: 钻孔过程中钻头尖端会产生热。过量的热量会导致钻头尖端的钻石以加速速度磨损。由于旋转钻床没有配备水冷系统, 而且由于我们的样品尺寸在毫米范围内, 钻头可以通过手动注入冷却液进入旋转钻头和平板之间的接触冷却。</li>
		<li>钻到至少3.25 毫米的深度 (样品的理想的最后高度的双重), 因此坚固高度留给结束表面准备之后。<ol>
<li>如果在缩回钻头后, 钻芯仍附着在试样板上, 然后将钻头绕在核心上, 然后缓慢摆动, 直到核心脱离板坯。</li>
			<li>如果钻孔的核心已经分离, 并卡在核心钻头的内部, 然后插入一个直径1.85 毫米的针从相反的一端, 推动核心向外部进行检索。</li>
		</ol>
</li>
		<li>使用湿巾干燥冷却水, 然后空气干燥回收的样品至少2小时, 如果可能的话, 隔夜。通过在一块低粘胶带上滚动, 清洁地核周围的灰尘。测量核心的直径, 并按最接近 1.9 + 毫米的直径来确定样品的优先级。</li>
		<li>下一步为端面的表面磨削准备. 注意:非常重要, 使端面触点平整, 以便在整个曲面区域上均匀分布所应用的负载。<ol>
<li>将沙纸放在研磨夹具下 (图 2b)。开始研磨与粗砂 (例如, 600 砂砾), 进展到一个更细的砂砾, 并完成至少1500的砂砾。将核心插入研磨夹具孔的一端。如果它不能紧紧地放在夹具的孔上, 请将胶带放在核心周围。 注意: 确保工作表面保持清洁, 以确保垂直度。</li>
			<li>将针脚 (直径1.4 毫米) 插入孔的另一端。继续按住 pin 轻轻向下, 以保持砂纸和核心在接触 (图 2b)。保持这个位置, 并开始慢慢研磨的核心对砂纸。拿出夹具的核心, 并经常检查, 以查看是否达到最后高度 (1.67 毫米), 如果表面是均匀的。</li>
			<li>对于平行度, 将样品插入回夹具以进一步研磨, 直到它达到0.5°内的精度。</li>
		</ol>
</li>
		<li>为了协助决定哪种样品最好使用, 用低放大 (2X–8X) 显微镜检查样品的整体形状。如果可能, 获得一些显微照片的样品, 以及文件。</li>
	</ol>
</li>
	<li>
矿物骨料样品
	<ol>
<li>先在杵和砂浆中研磨合适尺寸的岩石或预先存在的粉末, 准备矿物颗粒。 注: 这个过程可以通过使用旋转工具与磨头, 而不是杵。</li>
		<li>使用低放大显微镜测量晶粒尺寸。继续研磨直到颗粒的平均直径为4µm。<ol>
<li>将谷物悬浮在乙醇中。然后用一个高迁柱 (高度20厘米) 和重力沉降来将谷物与乙醇悬浮液分离。 注: 去除小于4µm (0.5 µm) 的谷物, 是以其质量为基础的。在谷物上作用的引力由: <img alt="Equation 1" src="/files/ftp_upload/57555/57555eq1.jpg"> 其中 m 是质量, g 是加速度由于重力。反对运动的力量是浮力和阻力。浮力由阿基米德的主体给出: <img alt="Equation 3" src="/files/ftp_upload/57555/57555eq3.jpg"> 其中ρ是密度, V 是位移流体的体积。拖动力由以下内容提供: <img alt="Equation 4" src="/files/ftp_upload/57555/57555eq4.jpg"> 如果 u 是粒子流体相对速度, 则p是投影在运动方向上的粒子区域, CD是拖动系数。通过平衡作用力, 设定晶粒达到终点速度的边界条件。假设层流条件下, 晶粒 v晶粒的速度在被称为斯托克斯定律的结果方程中给出: <img alt="Equation 5" src="/files/ftp_upload/57555/57555eq5.jpg"> 其中 d 是谷物的直径。</li>
		</ol>
</li>
		<li>将该柱中不同高度的乙醇/谷物混合物提取成单独的玻璃烧杯, 以获得按粒径排列的晶粒。 注: 谷物沉降率取决于其直径和密度。</li>
		<li>把内容放在烧杯一夜之间晾干。使用低放大率显微镜测量谷物的最终平均直径, 并选取与4µm 最接近的颗粒 (用于最佳 X 射线信号)。</li>
	</ol>
</li>
</ol>2. 细胞组装准备
<ol><li>
将准备好的样品装入标准的 D-直径单元组件 (图 3a)。 注: D-直径细胞总成是在地球科学 (COMPRES) 多砧电池组件开发项目14的材料性能研究联合体下开发的。以下描述标准 D-直径细胞设计 (在 COMPRES 项目下) 可用于增加温度, 如果需要的话。<ol>
<li>从单元格组件立方体开始 (6.18 毫米边缘长度;图 3)在干净的工作表面上。</li>
		<li>清洁氧化铝棒 (直径1.5 毫米, 高度1.46 毫米;图 3a)、氧化铝环 (图 3a) 和超声波浴中的石墨环 (图 3a)。在0.5°内准备氧化铝棒的端面并平行于精度 (参阅1.2.7 节)。</li>
		<li>把一块胶带放在立方体孔的一端。用一双镊子把两个环放在氧化铝棒周围, 并将它们全部插入到立方体的孔中, 这样石墨环就会与胶带接触。 注: 氧化铝环用作分离器;石墨环用于电导率在更高的温度应用 (不适用于本研究提出的冷压缩)。</li>
		<li>将多维数据集的拐角标记为与传入的 X 射线光束方向对齐 (图 4b)。 注: 钽箔用于获得更好的对比度, 以量化样品体积使用射线照相在实验期间 (第 3)。<ol>
<li>切一块长方形的钽箔 (1.5 毫米 x 17 毫米)。将箔折成 U 形片 (参见图 3b以了解更多详细信息) 并将其放置在单元格组件的圆柱空间内。为了确保箔和圆柱空间的边缘之间的紧密配合, 使用一个针 (直径为1.83 毫米), 以推上箔对边缘, 以消除任何多余的空间之间的两个。</li>
			<li>将此 U 形箔与 X 射线光束方向对齐 (图 4a), 目的是将箔和样品的2维投影分别最小化和最大化。</li>
		</ol>
</li>
		<li>在岩芯顶部放置一块矩形钽箔 (1.7 毫米 x 1 毫米) (图 3b)。确保箔是平的, 并对齐箔, 使箔的长度 (1.7 毫米) 垂直于 X 射线光束方向 (图 4a)。 注: 岩芯或矿物骨料可以是 "参考样品", 这取决于实验研究的目的。在这个特殊的例子中, 插入1.2 节中准备好的岩石芯。作为图 3b中的 "参考示例" 部分。这片箔的目的是为了更好地对比相邻样品之间的边界。</li>
		<li>用刮刀 (图 3b中的 "样本" 部分) 小心地将矿物骨料 (在1.3 节中准备) 放入圆柱空间。 注: 同样, 岩芯或矿物骨料可以是一个 "样本", 这取决于实验研究的目标。</li>
		<li>如有必要, 用空气轻轻地将多余的颗粒附着在圆柱空间的侧面。使用针 (直径1.83 毫米) 和卡尺检查是否达到了最终高度;在插入顶部氧化铝棒的高度留1.4 毫米。</li>
		<li>插入另一块长方形的钽箔 (1.7 毫米 x 1 毫米)。在超声波浴中清洁一组新的氧化铝棒 (直径1.5 毫米, 高度1.46 毫米), 氧化铝环和石墨环 (图 3a)。用一双镊子将两个环放在氧化铝棒周围, 然后将其插入, 使圆柱体的剩余空间完全填充在上面的石墨环上。</li>
		<li>使用少量的水泥 (锆粉与活化剂混合) 密封在立方体两端暴露的氧化铝棒。在水泥干燥后, 修剪剩余的钽箔, 仍然暴露在立方体外, 以整洁。</li>
	</ol>
</li>
</ol>3. 实验程序
注: 以下实验是在阿贡国家实验室的 APS 光束线 6-BM B (图4a) 上执行的。6-BM B 的实验是在白色 x 射线模式下进行的。这个光束线是一个开放的光束线, 欢迎科学家, 研究人员和世界各地的学生的建议, 在其一般用户程序下进行实验。
<ol><li>
通过收集氧化铝标准的衍射图样, 对系统进行能量标定。
	<ol>
<li>通过点击 "12 元素探测器控制泵" 面板上的 "开始" 按钮收集衍射图案。</li>
		<li>通过计算不同探测器的平均峰值位置 (水平移动 X、垂直 Y 和光束 Z 尺寸), 分析氧化铝 XRD 模式, 其中包含内置的 Cobalt-57 (Co-57) 荧光峰。</li>
		<li>在 "6 马达. adl" 面板中输入平均值作为新的基座位置。记得一个衍射模式, 并保存为能量色散衍射文件 (EDF), 这限制了2θ角和相关函数之间的探测器通道和 X 射线能量为每10探测器。</li>
	</ol>
</li>
	<li>去掉氧化铝标准, 并通过点击 "12 元素探测器控制泵" 面板上的 "启动" 按钮 (500s 的曝光时间, 优化信噪比) 来测量背景的衍射, 从而收集一个开放的 X 射线频谱。没有任何样品组装。</li>
	<li>用丙酮清洁铁砧 (截断边缘长度4毫米), 并使用便携式吸尘器清除以前实验中的所有碎片。将2节中编写的样品组件插入到实验设置的中心, 其中包括四、x 射线透明、烧结金刚石和两个碳化钨 (顶部/底部) 铁砧 (图 4b)。</li>
	<li>慢慢地降低对立的对侧铁砧同时。使用级别检查铁砧是否被调配。轻轻地推铁砧调整对齐, 直到它全部被夷为平地。底部和四横向铁砧现在应该都与样品组装。释放安全闩锁并插入间隔 (图 4a)。</li>
	<li>关闭哈奇, 使快门允许 X 射线束进入哈奇。</li>
	<li>在 "低压泵面板" (在图 5中标记为水泵马达控制器模块) 中, 打开 "低压泵" 按钮, 并按 "顶部 ram" 标签旁边的 "向上" 按钮, 将顶部 ram 移动到顶部, 对间隔 (图 4a)。借助实时 X 射线成像 (图 5), 开始缓慢而仔细地移动底部 ram, 直到铁砧开始出现在射线照相中。"留下一个非常细微的缺口", 这样在实验开始前, 样品就不会超载。</li>
	<li>
关闭低压泵控制器模块 (图 5) 上的所有控制, 并关闭 "加压" 阀, 然后再用高压液压泵进行压缩。 注: 高压泵使用基于史诗的软件进行控制 (图 5)。史诗是阿贡国家实验室开发的一种非商业性的开源软件工具、图书馆和应用。<ol>
<li>使用 "6 马达. adl" 面板中的 "慢跑" 按钮将样品位置移动到 Z 方向 (平行于光束), 这样, ImageJ 史诗区域探测器插件软件面板中的样本中心就与屏幕上的衍射焦点标记对齐。这减少了寄生衍射, 并优化了信噪比。</li>
	</ol>
</li>
	<li>通过点击 "12 元素探测器控制泵" 面板上的 "启动" 按钮来收集衍射光谱的核心和聚合 ("慢跑" 按钮沿底座 Z 移动样本之间) 分别, 每一个暴露时间的 500s, 在环境条件。在 "NDFileTIFF" 面板上, 单击 "捕获-开始" 按钮以捕获这些样本的射线照相 (图 5), 其曝光时间为 ~ 6 毫秒。</li>
	<li>通过启动马达, 在液压泵上运行的楔形导向块驱动铁砧向内。在 "SAM-85 新闻负载控制" 窗口 (图 6) 中, 将目标负载设置为50吨。打开反馈, 将速度控制的上限设置为 7 (可能最慢的压缩)。 注: 根据目标压力和压缩速度, 可以改变压力和速度。最大压力负荷, 以避免破坏的铁砧是100吨。</li>
	<li>使用 "衍射-成像-扫描-Prosilica" 面板 (图 7) 通过定义核心的所需位置来设置自动数据收集 (例如,按 x = 20.738 毫米, 按 Y = 4.3 毫米) 和聚合 (例如,按 x =20.738 毫米, 按 Y = 4.8 毫米) 进行衍射 (500s 的预设曝光时间) 和 X 射线照相成像。将所需的周期设置为 0, 这样数据收集将不断重复。单击 "开始" 以启动数据收集。 注意: 随着压缩的进展, 示例将向上移动, 因此需要相应更新新的所需位置。</li>
	<li>到达目标负载50吨后, 单击 "停止" 按钮以停止 "衍射-成像-扫描-Prosilica" 面板 (图 7) 中的自动数据收集。在 "SAM-85 压力控制" 窗口中, 将速度控制下限设置为-10, 并将目标负载更改为0吨, 从而解压缩样本。</li>
	<li>卸载后, 通过点击 "12 元素探测器控制泵" 面板上的 "启动" 按钮, 分别收集芯和骨料的衍射谱;对核心和聚合使用500s 的曝光时间。在 "NDFileTIFF" 面板上, 单击 "捕获-开始" 按钮以捕获这些样本的射线照相 (图 5), 其曝光时间为 ~ 6 毫秒。</li>
	<li>在低压泵面板 (在图 5中标记为泵马达控制器模块) 中, 打开 "加压阀"。按下 "低压泵-on" 按钮。按下 "顶部 ram" 和 "底部 ram" 标签旁边的 "向下" 按钮, 将顶部和底部 ram 向下移动, 直到绿色 "向下" 灯亮起, 然后停止驾驶两只公羊。</li>
	<li>在 "低压泵" 面板中, 在 "间隔块" 标签附近按出按钮, 将间隔臂移动到 "出" 位置, 然后按 "顶部 ram" 标签附近的 "向上" 按钮, 将顶部 ram 向上驱动直至安全锁啮合。之后, 在泵马达控制器单元 (图 5) 中关闭所有控件。慢慢地手动将侧向铁砧向外移动, 并移除试样组件。</li>
</ol>

作者声明没有利益冲突。

本文介绍了用 6-BM B 的多砧单元进行 XRD 实验的详细程序。也许上述协议中最关键、最具挑战性的步骤包括优化示例的质量。这种对样品质量的重要性几乎适用于所有的岩石和矿物变形实验。首先, 岩心的端面是平坦的, 两端平行, 同时垂直于圆柱面, 这是至关重要的。这将确保通过铁砧施加的外力通过样品的整个端面均匀分布。除了端面外, 试样所获得的圆柱面轮廓也很重要, 因为试样体积计算中的...

本文提出的方法的基本原理是在压缩和随后的压实过程中, 量化岩石和矿物骨料样品中的应力分布。了解岩石和矿物团聚体的压实对储层和岩土工程具有重要意义8,17,18,19,20,28 ,33。压实作用降低孔隙度, 从而导致孔隙压力的增加。任何这种增加的孔隙压力导致有效压力降低35。其结果是, 它将大大削弱储层岩石, 因此可以在较低的应力下经受过早的破坏。在地下的非弹性形变造成的后果的一些例子包括: 在油气藏持续长期生产方面的失败28,33, 地表下沉8,18,19,20和更改流体流模式17。因此, 全面了解岩石和矿物团聚体的压实过程有助于减少这种潜在的负面后果的可能性。
使用此处突出显示的方法的最大优点是, 它提供了一种方法, 用于在地质材料(5、6内对全局平均外部应用 压力12 内部的应力分布进行量化。,22. 此外, 作为一个原位实验, 应力分布的演化是时间解析的。外部施加的压力考虑范围从相对地低价值 (十兆帕) 到高价值 (几个 gigapascals)。样品中的应力是通过使用单个矿物颗粒内的原子晶格间距来间接测量的, 这是局部弹性应变5,6的度量。原子晶格间距是通过 x 射线的辅助来确定的, 通常是白色或单色 x 光的模式。对于白色 x 射线模式 (例如, DDIA 在6光束线的先进光子源 (APS), 阿贡国家实验室), 衍射光束 x 射线光束的强度是由一个不只是一个, 但由阵列的10元 Ge 探测器 (图 1) 沿固定圆方向分布, 在22.5°、45°、67.5°、90°、112.5°、135°、157.5°、180°、270°的方位角。对于单色 X 射线模式, 衍射图案使用 CCD 探测器 (例如, DDIA-30 在 GSECARS、APS、阿贡国家实验室)18、23的 13-ID D 光束线记录。两种 x 射线模式都可以定量地说明不同方向的应力是如何变化的。这一方法与以往在岩土材料的压实研究基本不同。
在典型的压实研究中, 圆柱形试样由执行器25在横截面积上应用的轴向力压缩。在这种情况下, 应用应力幅度的大小一般是通过简单地除以试样的初始横截面积来计算轴向力 (由荷载单元测量)。应该指出的是, 这种应用的应力幅度仅仅是一个平均值, 体积值, 因此, 不现实地表示局部应力状态是如何变化, 或分布在一个复杂的, 异构的粒状材料。碎屑沉积岩是复杂粒状材料的例子, 是由随后通过沉积和成岩过程压实和胶结的矿物颗粒聚集而成的,1,7,21,30,31. 这些聚集物自然地继承了由颗粒间空隙空间组成的孔隙, 这是由二次溶解修饰的晶粒填料的几何固有的。因此, 任何应用的应力预计将得到支持和集中在谷物到谷物接触, 并消失在晶粒孔界面。
除了颗粒材料内应力变化的复杂性外, 其他因素也进一步复杂化了在这些情况下研究压实的问题。首先, 局部应力场易受任何变化的影响, 因为微结构工件 (例如,晶粒形状, 先前存在的裂缝) 不可避免地存在于任何碎屑沉积岩中。第二, 虽然对试样表面施加的应力的大小可以完全量化, 但试样体内的应力分布仍受到很低的约束。一个最终效果32 -一种边界效应, 即平均应力集中在加载公羊和由于界面摩擦的试样之间的接触附近-众所周知, 在被压缩的圆柱形试样中展出。例如, 彭26展示了单向压缩花岗岩样品中的应变异质性, 受各种末端条件的限制。因此, 为了准确地计算颗粒材料中的局部应力分布, 我们提出了以下详细的协议, 即在岩石和矿物团聚体上进行 X 射线衍射 (XRD) 实验, 使用多砧变形装置在光束线6在阿贡国家实验室的 APS。

<table><tbody><tr><td>Rotatory Tool Workstation Drill Press Work Station with Wrench</td><td>Dremel</td><td>220-01</td><td></td></tr><tr><td>MultiPro Keyless Chuck</td><td>Dremel</td><td>4486</td><td></td></tr><tr><td>Variable-Speed Rotatory Tool&amp;nbsp;</td><td>Dremel</td><td>4000-6/50</td><td></td></tr><tr><td>Super small Diamond Core Drill - 2.5 mm</td><td>Dad&#039;s Rock Shop</td><td>SDCD</td><td></td></tr><tr><td>Coolant</td><td>NBK</td><td>JK-A-NBK-000-020</td><td>Grinding Fluid Concentrate US 5 gal / 20 L</td></tr><tr><td>commercial software package and codes for instrument control and data acquisition</td><td>IDL EPICS and SPEC</td><td></td><td>installed on the computer at the beamline</td></tr><tr><td>CCD Camera</td><td>Allied Vision</td><td>Prosilica GT</td><td>installed at the beamline</td></tr></tbody></table>

stress distribution during cold compression of rocks and mineral aggregates using synchrotron-based x-ray diffraction

我们报告了在多砧变形装置 (d-直径) 和同步辐射 X 射线耦合下对岩石和矿物集料进行压缩实验的详细程序。在室温下, 用一组四 x 射线透明烧结金刚石铁砧和两个碳化钨铁砧, 分别在横向和垂直平面上制备和压缩立方体状试样组件。所有六铁砧都安装在250吨的水压机内, 同时由两个楔形导向块驱动内部。一个水平能量色散 X 射线光束投射通过和衍射的样品组装。光束通常是白色或单色 x 射线的模式。在白色 x 射线的情况下, 衍射 x 射线是由固态探测器阵列检测而成的, 它收集产生的能量色散衍射模式。在单色 X 射线的情况下, 使用二维 (2 维) 探测器 (如成像板或电荷耦合器件 (CCD) 探测器) 记录衍射图案。分析了2维衍射模式, 推导出晶格间距。试样的弹性应变来源于晶粒内的原子晶格间距。然后用预定的弹性模量和弹性应变计算应力。此外, 二维应力分布可以理解不同方向的应力分布。此外, X 射线路径中的闪烁体产生了样本环境的可见光图像, 允许在实验过程中精确测量试样长度的变化, 从而直接测量试样的体积应变。这类实验可以量化岩土材料内的应力分布, 最终可以揭示出压实的机理。这些知识有可能大大提高我们对岩石力学、岩土工程、矿物物理和材料科学应用中的关键过程的理解, 压实过程是重要的。

我们展示一个代表性的结果例子从 XRD 实验 (实验 SIO2_55) 运行在多铁砧压力机在 6 bm B 在复合石英集5,6和 novaculite 核心样品6。石英集料和 novaculite 的晶粒尺寸为4µm 和 ~ 6–9µm, 分别为5、6。在本实验中收集的所选衍射谱在图 8中进行了说明。在环...

Watch this Scientific Journal Video about Stress Distribution During Cold Compression of Rocks and Mineral Aggregates Using Synchrotron-based X-Ray Diffraction at JoVE.com

Stress Distribution During Cold Compression of Rocks and Mineral Aggregates Using Synchrotron-based X-Ray Diffraction

我们报告了在多砧变形装置中结合同步辐射 X 射线的岩石和矿物团聚体压缩实验的详细程序。这样的实验可以量化样品内的应力分布, 最终揭示岩土材料中的压实过程。

基于同步辐射 x 射线衍射的岩石和矿物团聚体冷压缩应力分布

We report detailed procedures for performing compression experiments on rocks and mineral aggregates within a multi-anvil deformation apparatus (D-DIA) ...

stress-distribution-during-cold-compression-rocks-mineral-aggregates

Universidad de Cartagena UDEC

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Education

JoVE Core

JoVE Journal

Mechanical Engineering

Environment

Unit 1

Principal Stresses under a Given Loading

SCIENTISTS IN ACTION

9.6K 次观看.  Stony Brook University. 我们报告了在多砧变形装置中结合同步辐射 X 射线的岩石和矿物团聚体压缩实验的详细程序。这样的实验可以量化样品内的应力分布, 最终揭示岩土材料中的压实过程。

视频: Stress Distribution During Cold Compression of Rocks and Mineral Aggregates Using Synchrotron-based X-Ray Diffraction

Measuring Fluxes of Mineral Nutrients and Toxicants in Plants with Radioactive Tracers

Unidirectional influx and efflux of nutrients and toxicants, and their resultant net fluxes, are central to the nutrition and toxicology of plants. Radioisotope tracing is a major technique used to measure such fluxes, both within plants, and between plants and their environments. Flux data obtained with radiotracer protocols can help elucidate the capacity, mechanism, regulation, and energetics of transport systems for specific mineral nutrients or toxicants, and can provide insight into compartmentation and turnover rates of subcellular mineral and metabolite pools. Here, we describe two major radioisotope protocols used in plant biology: direct influx (DI) and compartmental analysis by tracer efflux (CATE). We focus on flux measurement of potassium (K+) as a nutrient, and ammonia/ammonium (NH3/NH4+) as a toxicant, in intact seedlings of the model species barley (Hordeum vulgare L.). These protocols can be readily adapted to other experimental systems (e.g., different species, excised plant material, and other nutrients/toxicants). Advantages and limitations of these protocols are discussed.

In planta measurement of nutrient and toxicant fluxes is essential to the study of plant nutrition and toxicity. Here, we cover radiotracer protocols for influx and efflux determination in intact plant roots, using potassium (K+) and ammonia/ammonium (NH3/NH4+) fluxes as examples. Advantages and limitations of such techniques are discussed.

植物与放射性示踪剂测量矿质营养和毒物的通量

Unidirectional influx and efflux of nutrients and toxicants, and their resultant net fluxes, are central to the nutrition and toxicology of plants. ...

科研

环境科学

Synthesis and Microdiffraction at Extreme Pressures and Temperatures

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary interiors, design materials with novel properties, understand the mechanical behavior of materials exposed to very high stresses as in explosions or impacts. Synthesis and structural analysis of materials at extreme conditions of pressure and temperature entails remarkable technical challenges. In the laser heated diamond anvil cell (LH-DAC), very high pressure is generated between the tips of two opposing diamond anvils forced against each other; focused infrared laser beams, shined through the diamonds, allow to reach very high temperatures on samples absorbing the laser radiation. When the LH-DAC is installed in a synchrotron beamline that provides extremely brilliant x-ray radiation, the structure of materials under extreme conditions can be probed in situ. LH-DAC samples, although very small, can show highly variable grain size, phase and chemical composition. In order to obtain the high resolution structural analysis and the most comprehensive characterization of a sample, we collect diffraction data in 2D grids and combine powder, single crystal and multigrain diffraction techniques. Representative results obtained in the synthesis of a new iron oxide, Fe4O5 1 will be shown.

The laser heated diamond anvil cell combined with synchrotron micro-diffraction techniques allows researchers to explore the nature and properties of new phases of matter at extreme pressure and temperature (PT) conditions. Heterogeneous samples can be characterized in situ under high pressure by 2D mapping and combined powder, single-crystal and multigrain diffraction approaches.

在极端的压力和温度的合成和Microdiffraction

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary ...

工程学

Extracting Metrics for Three-dimensional Root Systems: Volume and Surface Analysis from In-soil X-ray Computed Tomography Data

Plant roots play a critical role in plant-soil-microbe interactions that occur in the rhizosphere, as well as processes with important implications to climate change and crop management. Quantitative size information on roots in their native environment is invaluable for studying root growth and environmental processes involving plants. X-ray computed tomography (XCT) has been demonstrated to be an effective tool for in situ root scanning and analysis. We aimed to develop a costless and efficient tool that approximates the surface and volume of the root regardless of its shape from three-dimensional (3D) tomography data. The root structure of a Prairie dropseed (Sporobolus heterolepis) specimen was imaged using XCT. The root was reconstructed, and the primary root structure was extracted from the data using a combination of licensed and open-source software. An isosurface polygonal mesh was then created for ease of analysis. We have developed the standalone application imeshJ, generated in MATLAB1, to calculate root volume and surface area from the mesh. The outputs of imeshJ are surface area (in mm2) and the volume (in mm3). The process, utilizing a unique combination of tools from imaging to quantitative root analysis, is described. A combination of XCT and open-source software proved to be a powerful combination to noninvasively image plant root samples, segment root data, and extract quantitative information from the 3D data. This methodology of processing 3D data should be applicable to other material/sample systems where there is connectivity between components of similar X-ray attenuation and difficulties arise with segmentation.

A methodology for obtaining visual and quantitative root structure information from X-ray computed tomography data acquired in-soil is presented.

从在土X射线计算机断层扫描数据量和表面分析:提取指标三维根系

Plant roots play a critical role in plant-soil-microbe interactions that occur in the rhizosphere, as well as processes with important implications to ...

Integrating Remote Sensing with Species Distribution Models; Mapping Tamarisk Invasions Using the Software for Assisted Habitat Modeling (SAHM)

Early detection of invasive plant species is vital for the management of natural resources and protection of ecosystem processes. The use of satellite remote sensing for mapping the distribution of invasive plants is becoming more common, however conventional imaging software and classification methods have been shown to be unreliable. In this study, we test and evaluate the use of five species distribution model techniques fit with satellite remote sensing data to map invasive tamarisk (Tamarix spp.) along the Arkansas River in Southeastern Colorado. The models tested included boosted regression trees (BRT), Random Forest (RF), multivariate adaptive regression splines (MARS), generalized linear model (GLM), and Maxent. These analyses were conducted using a newly developed software package called the Software for Assisted Habitat Modeling (SAHM). All models were trained with 499 presence points, 10,000 pseudo-absence points, and predictor variables acquired from the Landsat 5 Thematic Mapper (TM) sensor over an eight-month period to distinguish tamarisk from native riparian vegetation using detection of phenological differences. From the Landsat scenes, we used individual bands and calculated Normalized Difference Vegetation Index (NDVI), Soil-Adjusted Vegetation Index (SAVI), and tasseled capped transformations. All five models identified current tamarisk distribution on the landscape successfully based on threshold independent and threshold dependent evaluation metrics with independent location data. To account for model specific differences, we produced an ensemble of all five models with map output highlighting areas of agreement and areas of uncertainty. Our results demonstrate the usefulness of species distribution models in analyzing remotely sensed data and the utility of ensemble mapping, and showcase the capability of SAHM in pre-processing and executing multiple complex models.

Integrating Remote Sensing with Species Distribution Models; Mapping Tamarisk Invasions Using the Software for Assisted Habitat Modeling SAHM

We demonstrate the utility of remotely sensed data and the newly developed Software for Assisted Habitat Modeling (SAHM) in predicting invasive species occurrence on the landscape. An ensemble of predictive models produced highly accurate maps of tamarisk (Tamarix spp.) invasion in Southeastern Colorado, USA when assessed with subsequent field validations.

整合与物种分布模型遥感;映射红柳入侵使用软件进行辅助建模居（SAHM）

Early detection of invasive plant species is vital for the management of natural resources and protection of ecosystem processes. The use of satellite ...

A Method for Studying the Temperature Dependence of Dynamic Fracture and Fragmentation

The dynamic fracture of a body is a late-stage phenomenon typically studied under simplified conditions, in which a sample is deformed under uniform stress and strain rate. This can be produced by evenly loading the inner surface of a cylinder. Due to the axial symmetry, as the cylinder expands the wall is placed into a tensile hoop stress that is uniform around the circumference. While there are various techniques to generate this expansion such as explosives, electromagnetic drive, and existing gas gun techniques they are all limited in the fact that the sample cylinder must be at room temperature. We present a new method using a gas gun that facilitates experiments on cylinders from 150 K to 800 K with a consistent, repeatable loading. These highly diagnosed experiments are used to examine the effect of temperature on the fracture mechanisms responsible for failure, and their resulting influence on fragmentation statistics. The experimental geometry employs a steel ogive located inside the target cylinder, with the tip located about halfway in. A single stage light gas gun is then used to launch a polycarbonate projectile into the cylinder at 1,000 m/sec-1. The projectile impacts and flows around the rigid ogive, driving the sample cylinder from the inside. The use of a non-deforming ogive insert allows us to install temperature control hardware inside the rear of the cylinder. Liquid nitrogen (LN2) is used for cooling and a resistive high current load for heating. Multiple channels of upshifted photon Doppler velocimetry (PDV) track the expansion velocity along the cylinder enabling direct comparison to computer simulations, while High speed imaging is used to measure the strain to failure. The recovered cylinder fragments are also subject to optical and electron microscopy to ascertain the failure mechanism.

Fracture and fragmentation are late stage phenomena in dynamic loading scenarios and are typically studied using explosives. We present a technique for driving expansion using a gas gun which uniquely enables control of both loading rate and sample temperature.

为研究动态断裂及破碎的温度敏感性的方法

The dynamic fracture of a body is a late-stage phenomenon typically studied under simplified conditions, in which a sample is deformed under uniform ...

High-pressure, High-temperature Deformation Experiment Using the New Generation Griggs-type Apparatus

In order to address geological processes at great depths, rock deformation should ideally be tested at high pressure (&#62; 0.5 GPa) and high temperature (&#62; 300 &#176;C). However, because of the low stress resolution of current solid-pressure-medium apparatuses, high-resolution measurements are today restricted to low-pressure deformation experiments in the gas-pressure-medium apparatus. A new generation of solid-medium piston-cylinder (&#34;Griggs-type&#34;) apparatus is here described. Able to perform high-pressure deformation experiments up to 5 GPa and designed to adapt an internal load cell, such a new apparatus offers the potential to establish a technological basis for high-pressure rheology. This paper provides video-based detailed documentation of the procedure (using the &#34;conventional&#34; solid-salt assembly) to perform high-pressure, high-temperature experiments with the newly designed Griggs-type apparatus. A representative result of a Carrara marble sample deformed at 700 &#176;C, 1.5 GPa and 10-5 s-1 with the new press is also given. The related stress-time curve illustrates all steps of a Griggs-type experiment, from increasing pressure and temperature to sample quenching when deformation is stopped. Together with future developments, the critical steps and limitations of the Griggs apparatus are then discussed.

Rock deformation needs to be quantified at high pressure. A description of the procedure to perform deformation experiments in a newly designed solid-medium Griggs-type apparatus is here given. This provides technological basis for future rheological studies at pressures up to 5 GPa.

新一代格雷型装置高压高温变形试验

In order to address geological processes at great depths, rock deformation should ideally be tested at high pressure (&#62; 0.5 GPa) and high temperature ...

High Pressure Single Crystal Diffraction at PX^2

In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the GSECARS 13-BM-C beamline at the Advanced Photon Source. The DAC program at 13-BM-C is part of the Partnership for Extreme Xtallography (PX^2) project. BX-90 type DACs with conical-type diamond anvils and backing plates are recommended for these experiments. The sample chamber should be loaded with noble gas to maintain a hydrostatic pressure environment. The sample is aligned to the rotation center of the diffraction goniometer. The MARCCD area detector is calibrated with a powder diffraction pattern from LaB6. The sample diffraction peaks are analyzed with the ATREX software program, and are then indexed with the RSV software program. RSV is used to refine the UB matrix of the single crystal, and with this information and the peak prediction function, more diffraction peaks can be located. Representative single crystal diffraction data from an omphacite (Ca0.51Na0.48)(Mg0.44Al0.44Fe2+0.14Fe3+0.02)Si2O6 sample were collected. Analysis of the data gave a monoclinic lattice with P2/n space group at 0.35 GPa, and the lattice parameters were found to be: a = 9.496 &#177;0.006 &#197;, b = 8.761 &#177;0.004 &#197;, c = 5.248 &#177;0.001 &#197;, &#946; = 105.06 &#177;0.03&#186;, &#945; = &#947; = 90&#186;.

In this report, we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell at the GSECARS 13-BM-C beamline at the Advanced Photon Source. ATREX and RSV programs are used to analyze the data.

高压单晶衍射PX ^ 2

In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the ...

化学

Synchrotron X-ray Microdiffraction and Fluorescence Imaging of Mineral and Rock Samples

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder microdiffraction two-dimensional (2D) maps at beamline 12.3.2 of the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory. Measurements can be performed on any sample that is less than 10 cm x 10 cm x 5 cm, with a flat exposed surface. The experimental geometry is calibrated using standard materials (elemental standards for XRF, and crystalline samples such as Si, quartz, or Al2O3 for diffraction). Samples are aligned to the focal point of the x-ray microbeam, and raster scans are performed, where each pixel of a map corresponds to one measurement, e.g., one XRF spectrum or one diffraction pattern. The data are then processed using the in-house developed software XMAS, which outputs text files, where each row corresponds to a pixel position. Representative data from moissanite and an olive snail shell are presented to demonstrate data quality, collection, and analysis strategies.

We describe a beamline setup meant to carry out rapid two-dimensional x-ray fluorescence and x-ray microdiffraction mapping of single crystal or powder samples using either Laue (polychromatic radiation) or powder (monochromatic radiation) diffraction. The resulting maps give information about strain, orientation, phase distribution, and plastic deformation.

矿物和岩石样品的同步辐射 x 射线 Microdiffraction 和荧光成像

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder ...

Visualization of Failure and the Associated Grain-Scale Mechanical Behavior of Granular Soils under Shear using Synchrotron X-Ray Micro-Tomography

The rapid development of X-ray imaging techniques with image processing and analysis skills has enabled the acquisition of CT images of granular soils with high-spatial resolutions. Based on such CT images, grain-scale mechanical behavior such as particle kinematics (i.e., particle translations and particle rotations), strain localization and inter-particle contact evolution of granular soils can be quantitatively investigated. However, this is inaccessible using conventional experimental methods. This study demonstrates the exploration of the grain-scale mechanical behavior of a granular soil sample under triaxial compression using synchrotron X-ray micro-tomography (&#956;CT). With this method, a specially fabricated miniature loading apparatus is used to apply confining and axial stresses to the sample during the triaxial test. The apparatus is fitted into a synchrotron X-ray tomography setup so that high-spatial resolution CT images of the sample can be collected at different loading stages of the test without any disturbance to the sample. With the capability of extracting information at the macro scale (e.g., sample boundary stresses and strains from the triaxial apparatus setup) and the grain scale (e.g., grain movements and contact interactions from the CT images), this procedure provides an effective methodology to investigate the multi-scale mechanics of granular soils.

The protocol describes procedures to acquire high-spatial resolution computed tomography (CT) images of a granular soil during triaxial compression, and to apply image processing techniques to these CT images to explore the grain-scale mechanical behavior of the soil under loading.

使用同步加速器 X 射线微断层扫描技术，在剪切下对颗粒土壤的故障和相关的颗粒级机械性能进行可视化

The rapid development of X-ray imaging techniques with image processing and analysis skills has enabled the acquisition of CT images of granular soils ...

An Externally-Heated Diamond Anvil Cell for Synthesis and Single-Crystal Elasticity Determination of Ice-VII at High Pressure-Temperature Conditions

The externally-heated diamond anvil cell (EHDAC) can be used to generate simultaneously high-pressure and high-temperature conditions found in Earth&#8217;s and planetary interiors. Here we describe the design and fabrication of the EHDAC assemblies and accessories, including ring resistive heaters, thermal and electrical insulating layers, thermocouple placement, as well as the experimental protocol for preparing the EHDAC using these parts. The EHDAC can be routinely used to generate megabar pressures and up to 900 K temperatures in open air, and potentially higher temperatures up to ~1200 K with a protective atmosphere (i.e., Ar mixed with 1% H2). Compared with a laser-heating method for reaching temperatures typically &#62;1100 K, external heating can be easily implemented and provide a more stable temperature at &#8804;900 K and less temperature gradients to the sample. We showcased the application of the EHDAC for synthesis of single crystal ice-VII and studied its single-crystal elastic properties using synchrotron-based X-ray diffraction and Brillouin scattering at simultaneously high-pressure high-temperature conditions.

This work focuses on the standard protocol for preparing the externally-heated diamond anvil cell (EHDAC) for generating high-pressure and high-temperature (HPHT) conditions. The EHDAC is employed to investigate materials in Earth and planetary interiors under extreme conditions, which can be also used in solid state physics and chemistry studies.