Name: measuring the densities of aqueous glasses at cryogenic temperatures
Uploaded: 2017-06-28T14:00:00
Description: Watch this Scientific Journal Video about Measuring the Densities of Aqueous Glasses at Cryogenic Temperatures at JoVE.com

这项工作得到国家科学基金会的授权MCB-1330685的支持。 DWM承认康奈尔大学分子生物物理学培训基金（NIH T32GM0082567）的部分支持。

小心：使用前请咨询所有相关的材料安全数据表（MSDS）。使用压缩气体时，请使用适当的安全措施，包括适当的校准气体处理调节器和阀门以及认可的气体管道。与液态冷冻剂接触会导致严重的冻伤和坏死。使用适当的个人防护设备（面罩，手套，实验室外套，全长裤，闭式脚趾鞋），所有这些都必须不透液体。保持静置，并确保在使用液体冷冻剂时从设备畅通无阻的出口路径。注意使用压缩气...

<ol>
	<li>Fahy, G. M., Wowk, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Principles+of+Cryopreservation+by+Vitrification.">Principles of Cryopreservation by Vitrification.</a> Cryopreservation and Freeze-Drying Protocols. , 21-82 (2015).</li><li>Nagy, Z. P., Nel-Themaat, L., Chang, C. -. C., Shapiro, D. B., Berna, D. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cryopreservation+of+eggs.">Cryopreservation of eggs.</a> Human Fertility: Methods and Protocols. , 439-454 (2014).</li><li>Kriminski, S., Caylor, C. L., Nonato, M. C., Finkelstein, K. D., Thorne, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flash+cooling+and+annealing+of+protein+crystals.">Flash cooling and annealing of protein crystals.</a> Acta Cryst Sect D. 58 (3), 459-471 (2002).</li><li>Juers, D. H., Matthews, B. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reversible+lattice+repacking+illustrates+the+temperature+dependence+of+macromolecular+interactions.">Reversible lattice repacking illustrates the temperature dependence of macromolecular interactions.</a> J Mol Biol. 311 (4), 851-862 (2001).</li><li>Juers, D. H., Matthews, B. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cryo-cooling+in+macromolecular+crystallography:+advantages,+disadvantages+and+optimization.">Cryo-cooling in macromolecular crystallography: advantages, disadvantages and optimization.</a> Q Rev Biophys. 37 (2), 105-119 (2004).</li><li>Alcorn, T., Juers, D. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progress+in+rational+methods+of+cryoprotection+in+macromolecular+crystallography.">Progress in rational methods of cryoprotection in macromolecular crystallography.</a> Acta Cryst Sect D. 66 (4), 366-373 (2010).</li><li>Warkentin, M., Sethna, J., Thorne, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+Droplet+Theory+Explains+the+Glass+Formability+of+Aqueous+Solutions.">Critical Droplet Theory Explains the Glass Formability of Aqueous Solutions.</a> Phys Rev Lett. 110 (1), 15703 (2013).</li><li>Kriminski, S., Kazmierczak, M., Thorne, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heat+transfer+from+protein+crystals:+implications+for+flash-cooling+and+X-ray+beam+heating.">Heat transfer from protein crystals: implications for flash-cooling and X-ray beam heating.</a> Acta Cryst Sect D. 59 (4), 697-708 (2003).</li><li>Loerting, T., Bauer, M., Kohl, I., Watschinger, K., Winkel, K., Mayer, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cryoflotation:+Densities+of+amorphous+and+crystalline+ices.">Cryoflotation: Densities of amorphous and crystalline ices.</a> J Phys Chem B. 115 (48), 14167-14175 (2011).</li><li>Shen, C., Julius, E. F., Tyree, T. J., Moreau, D. W., Thorne, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermal+contraction+of+aqueous+glycerol+and+ethylene+glycol+solutions+for+optimized+protein-crystal+cryoprotection+Thermal+contraction+of+aqueous+glycerol+and+ethylene+glycol+solutions+for+optimized+protein-crystal+cryoprotection.">Thermal contraction of aqueous glycerol and ethylene glycol solutions for optimized protein-crystal cryoprotection Thermal contraction of aqueous glycerol and ethylene glycol solutions for optimized protein-crystal cryoprotection.</a> Acta Cryst Sect D. 72 (6), 742-752 (2016).</li><li>Warkentin, M., Berejnov, V., Husseini, N. S., Thorne, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyperquenching+for+protein+cryocrystallography.">Hyperquenching for protein cryocrystallography.</a> J Appl Cryst. 39 (6), 805-811 (2006).</li><li>McFerrin, M. B., Snell, E. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+development+and+application+of+a+method+to+quantify+the+quality+of+cryoprotectant+solutions+using+standard+area-detector+X-ray+images.">The development and application of a method to quantify the quality of cryoprotectant solutions using standard area-detector X-ray images.</a> J Appl Cryst. 35 (5), 538-545 (2002).</li><li>Chinte, U., Shah, B., DeWitt, K., Kirschbaum, K., Pinkerton, A. A., Schall, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sample+size:+An+important+parameter+in+flash-cooling+macromolecular+crystallization+solutions.">Sample size: An important parameter in flash-cooling macromolecular crystallization solutions.</a> J. Appl. Cryst. 38 (3), 412-419 (2005).</li><li>Bosart, L. W., Snoddy, A. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Specific+gravity+of+glycerol.">Specific gravity of glycerol.</a> Ind Eng Chem. 20 (12), 1377-1379 (1928).</li><li>Rodrigues, M., Francesconi, A. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+study+of+the+excess+molar+volumes+of+binary+and+ternary+mixtures+containing+water+++(1,2-ethanediol,+or+1,2-propanediol,+or+1,3-propanediol,+or+1,2-butanediol)+++(1-n-butyl-3-methylimidazolium+bromide)+at+298.15+K+and+atmospheric+pressure.">Experimental study of the excess molar volumes of binary and ternary mixtures containing water + (1,2-ethanediol, or 1,2-propanediol, or 1,3-propanediol, or 1,2-butanediol) + (1-n-butyl-3-methylimidazolium bromide) at 298.15 K and atmospheric pressure.</a> J Solution Chem. 40 (11), 1863-1873 (2011).</li><li>Berejnov, V., Husseini, N. S., Alsaied, O. A., Thorne, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+cryoprotectant+concentration+and+cooling+rate+on+vitrification+of+aqueous+solutions.">Effects of cryoprotectant concentration and cooling rate on vitrification of aqueous solutions.</a> J Appl Cryst. 39 (2), 244-251 (2006).</li><li>Meisburger, S. P., Warkentin, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Breaking+the+Radiation+Damage+Limit+with+Cryo-SAXS.">Breaking the Radiation Damage Limit with Cryo-SAXS.</a> Biophys J. 104 (1), 227-236 (2013).</li></ol>

主要由具有对仪器制造工具和机械的访问限制的本科生开发的本设备和方法仍然为低至50pL的单个液滴提供高精度的密度测量。在接近和高于50％w / w的浓度范围内，其中小的冷却速度足以获得玻璃化样品，其密度与先前对散装样品的测量结果一致。目前密度的外推至0％浓度 - 纯水 - 也与77 K 9的低密度无定形冰的接受密度相当吻合。 根据使给定液滴组成中性?...

水和含水混合物在其各个阶段的物理性质是基本兴趣的，并且对体内和体外对生物系统的理解是重要的。在当代冷冻生物学和生物冷冻保存中，含水冷冻保护剂混合物的玻璃体或非晶相特别令人关注1,2 。冰晶的成核和生长可能破坏细胞和组织，并促进蛋白质变性和聚集，因此使溶剂玻璃化的冷冻保存方案变得越来越受欢迎。在生物分子晶体学中，生物分子之间的通道中溶剂的结晶破坏了晶格并降低了衍射性质。玻璃化通过快速冷却，脱水和加入冷冻保护性溶质如甘油，乙二醇，聚乙二醇（PEG），醇和盐。 玻璃化限制冰结晶和生长，但不能消除所有与冷却有关的样品损伤。例如，当蛋白质晶体冷却到玻璃化状态3时，晶体的马赛克（晶体取向的分布的度量）通常增加10到100倍，玻璃化精子细胞和卵母细胞的解冻后存活率变化很大。 一种损伤机理是冷却3,4,5时溶剂和周围物质的不均匀收缩。晶体，细胞或组织中的平衡溶剂和溶质浓度是温度依赖性的，溶剂加溶质和周围材料可能会以不同的量收缩。快速冷却可能会在玻璃化之前防止溶剂和溶质再分配，并且差异收缩<html>可能导致大的不均匀的非平衡应力，导致样品损坏。 因此，减少冷却诱发的损伤的合理方法可以从对液体和玻璃化含水混合物的温度依赖密度的了解中获益。在溶质浓度超过溶液重量（w / w）的50％以上的溶质浓度下，大多数含水冷冻保护剂混合物可以以10 K / s或更低的适度冷却速率进行玻璃化，从而允许使用大玻璃样品进行生产和密度测量。然后可以使用阿基米德原理，通过测量悬浮在诸如氮气的液体冷冻剂中时样品的表观重量来确定密度。然而，随着溶质浓度的降低，玻璃化所需的冷却速度迅速增加：甘油水溶液的冷却速率从溶液50重量％到溶液体积（mL / w）至&lt;1,000 K时提高至&gt; 1,000 25％w / v的K / sass =“xref”&gt; 7。热传递成为边界层限制，从而实现更大的冷却速度需要更小和更小的样品8 。 纯玻璃水和冰的密度的测量已经通过将真空中的微米直径（femtoliter volume）的液滴沉积到低温冷却的表面上来实现，以便建立宏观（克质量）样品。该样品的密度通过在液氮 - 氩混合物中的低温放置测定，其中调节低温液体的密度直到样品变得中性浮力9 。然而，以最小化空隙体积的方式从大量小滴中产生大量样品 - 这是先前玻璃态相密度测量中重要的误差源 - 是不重要的。对于含水混合物，在气雾化和真空沉积期间溶液组分的差异蒸发可导致沉积浓度的重大不确定性。 我们已经开发了一种基于低温分析法的方法，可以使用小至50 pL 10的各种液滴进行精确的含水混合物密度测定。这些液滴可以快速冷却，同时保持其原始浓度，并且可以使用与X射线衍射测量相关的简单目视测定来评估其低温状态（玻璃化或结晶）。该方法广泛适用于水性和非水性混合物，并且可以扩展到各种生物样品，包括细胞（ 例如茎和卵），组织样品和蛋白质晶体，其低温密度为0.8-1.4g /毫升。

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">centrifuge tube</td>
			<td style="width:71px;">Falcon</td>
			<td style="width:119px;">6029236</td>
			<td style="width:167px;">15 mL conical centrifuge tube</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">glycerol, &#62;99.5%</td>
			<td style="width:71px;">Sigma&#160;</td>
			<td style="width:119px;">G9012-100 mL</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">ethylene glycol, &#62;99.8%</td>
			<td style="width:71px;">Sigma</td>
			<td>324558-100 mL</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">analytical microbalance</td>
			<td style="width:71px;">Mettler</td>
			<td style="width:119px;">AE240</td>
			<td>Analytical balance, 0.01 mg resolution, has hook on bottom for weighing below the balance&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">vortexer</td>
			<td style="width:71px;">Scientific Industries</td>
			<td style="width:119px;">SI-0236</td>
			<td>Vortex-Genie 2</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Apparatus enclosure framing</td>
			<td style="width:71px;">Unistrut&#160;</td>
			<td style="width:119px;">1-5/8&#34; metal framing</td>
			<td>48&#34; wide x 24&#34; deep x 40&#34; tall&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Apparatus enclosure air barrier</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>any clear plastic sheeting</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">neoprene rubber disk</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>4&#34; diameter, 1/8&#34; thick</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">dewar flask</td>
			<td style="width:71px;">Scilogix Dilvac</td>
			<td style="width:119px;">SS333</td>
			<td>4.5 liter dewar flask with steel case and clamp lid</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">copper chamber</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>This fabricated part is comprised of a 1.43&#34; diameter, 0.017&#34; wall thickness copper tube with a solid cylindrical copper base soldered to seal one end.&#160; The copper base is 0.87&#34; tall and the overall chamber height is 7&#34;.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">nitrogen gas</td>
			<td style="width:71px;">Airgas</td>
			<td style="width:119px;">NI HP300</td>
			<td>99.998% pure N2 gas</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">argon gas</td>
			<td style="width:71px;">Airgas</td>
			<td style="width:119px;">AR HP300</td>
			<td>99.998% pure Ar gas</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">rotameter</td>
			<td style="width:71px;">Omega</td>
			<td style="width:119px;">FL3692ST</td>
			<td>2.52 l/min max flow rate</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:216px;">foam insulating lid</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>This part is fabricated from 4 lb/ft3 crosslinked polyethylene foam (supplied by Technifab, 1355 Chester Industrial Parkway, Avon, OH), and has an OD of 2.42&#34;, and ID of 1.52&#34;, and a thickness of 0.79&#34;.&#160;&#160;&#160;&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">PTFE test mass</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>This fabricated part is a 0.246&#34; diameter, 0.580&#34; tall cylinder with a 0.060&#34; diameter hole running perpendicular to and intersecting the cylinder axis ~0.10&#34; from one end.&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">microbalance platform</td>
			<td style="width:71px;">Unistrut</td>
			<td style="width:119px;">1-5/8&#34; metal framing</td>
			<td>11&#34; wide x 24&#34; long x 24&#34; high rectangular frame with an top aluminum sheet containing a hole for the monofilament and hanging test mass</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">2 mil (50 um) monofilament line</td>
			<td style="width:71px;">Berkley</td>
			<td style="width:119px;">NF1502-CM</td>
			<td>Nanofil fishing line</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Argon precooling coil tubing</td>
			<td style="width:71px;">VWR</td>
			<td style="width:119px;">60985-512</td>
			<td>1/8&#34; ID x 1/4&#34; OD PVC tubing</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:216px;">perforated copper foil mixer</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>1.4&#34; diameter,&#160; 35 micron thick copper disk, cut from 1 ounce/ft2 copper sheet and perforated with holes using an awl or other sharp pointed tool.&#160; Insert 1-2 mm diameter rigid thermally insulating (plastic or wood) rod into the center and fix using epoxy as needed.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">syringe</td>
			<td style="width:71px;">BD</td>
			<td style="width:119px;">309628</td>
			<td>1 ml Luer-Lok tip syringe</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">vacuum generator</td>
			<td style="width:71px;">Gast</td>
			<td style="width:119px;">VG-015-00-00</td>
			<td>compressed air venturi single stage vacuum generator</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">hydrophobic coating spray</td>
			<td style="width:71px;">RainX</td>
			<td style="width:119px;">620036</td>
			<td>plastic water repellent</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">long focal length stereo microscope</td>
			<td style="width:71px;">Bausch and Lomb Stereozoom 6</td>
			<td style="width:119px;"></td>
			<td>0.67-4 x zoom pod with 20x eyepieces, 10 cm working distance&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">LED ring illuminator</td>
			<td style="width:71px;">Amscope</td>
			<td style="width:119px;">LED144S</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">LED spot illuminator</td>
			<td style="width:71px;">Newhouse Lighting</td>
			<td style="width:119px;">NHCLP-LED</td>
			<td>3W LED gooseneck clamp lamp</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">1.8 ml cryo vial</td>
			<td style="width:71px;">Nunc</td>
			<td>V7634-500EA</td>
			<td>Any 1.8 or 2 ml cryovial is adequate</td>
		</tr>
	</tbody>
</table>

measuring the densities of aqueous glasses at cryogenic temperatures

我们展示了一种确定含水混合物和需要快速冷却的其他样品的玻璃态低温温度密度以制备所需低温温度相的方法。通过投影到液氮 - 氩（N 2 -Ar）混合物来冷却微升至皮升级的液滴。使用与X射线衍射测量相关的视觉测定来评估液滴的低温温度相。通过添加N 2或Ar来调节液体N 2 -Ar混合物的密度，直到液滴变得中性浮力。使用测试质量和阿基米德原理确定该混合物的密度以及因此的液滴密度。在液体制备中适当的注意，管理液体冷冻剂混合物以上的气体以最小化结冰，以及定期混合低温混合物以防止密度分层和相分离，精度至&lt;0.5％的滴度小至50 pL的密度容易确定。水冷冻保护剂混合物的测量提供了对冷冻保护剂作用的了解，并提供定量数据以促进生物冷冻保存中的热收缩匹配。

分别在图 1A和图1B中分别显示了T = 77K下玻璃化甘油水溶液和乙二醇水溶液的密度测量值，以及T = 298 K和77 K之间的比容量的相应变化，确定的T = 298K密度， 如图2所示。在高冷冻保护剂浓度下，溶液在冷却至玻璃化状态时收缩，而纯水膨胀。预测两种冷冻保护剂的近20-25％w / ...

Watch this Scientific Journal Video about Measuring the Densities of Aqueous Glasses at Cryogenic Temperatures at JoVE.com

Measuring the Densities of Aqueous Glasses at Cryogenic Temperatures

描述了一种用于在低温下测定含水混合物的微米到微米级的玻璃体相密度的方案。

在低温下测量水性玻璃的密度

We demonstrate a method for determining the vitreous phase cryogenic temperature densities of aqueous mixtures, and other samples that require rapid ...

Research

JoVE Journal

Engineering

Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures

在极低的温度下角分辨光电子能谱

The physical properties of a material are defined by its  electronic structure. Electrons in solids are characterized by energy (&omega;)  and momentum ...

科研

工程学

Synthesis and Microdiffraction at Extreme Pressures and Temperatures

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 ...

Experimental Measurement of Settling Velocity of Spherical Particles in Unconfined and Confined Surfactant-based Shear Thinning Viscoelastic Fluids

无约束和封闭表面活性剂中球形粒子沉降速度的实验测量 剪切变薄粘性流体

An experimental study is performed to measure the terminal settling velocities of spherical particles in surfactant based shear thinning viscoelastic ...

Ambient Method for the Production of an Ionically Gated Carbon Nanotube Common Cathode in Tandem Organic Solar Cells

对于一个以离子门控碳纳米管共阴极的串联有机太阳能电池的生产环境法

A method of fabricating organic photovoltaic (OPV) tandems that requires no vacuum processing is presented. These devices are comprised of two ...

A Simple Dewar/Cryostat for Thermally Equilibrating Samples at Known Temperatures for Accurate Cryogenic Luminescence Measurements

一个简单的杜瓦瓶/低温恒温器的热的样品配平在为准确低温发光测量已知温度

The design and operation of a simple liquid nitrogen Dewar/cryostat apparatus based upon a small fused silica optical Dewar, a thermocouple assembly, and ...

Design and Evaluation of Smart Glasses for Food Intake and Physical Activity Classification

食品摄取及运动分级智能眼镜的设计与评价

This study presents a series of protocols of designing and manufacturing a glasses-type wearable device that detects the patterns of temporalis muscle ...

Processing of Bulk Nanocrystalline Metals at the US Army Research Laboratory

美国陆军研究实验室散装纳米晶金属的加工

Given their potential for significant property improvements relative to their large grained counterparts, much work has been devoted to the continued ...

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

结构转换的原位和原位研究方法: 金属玻璃结晶的实例

We demonstrate the use of two nuclear-based analytical methods that can follow the modifications of microstructural arrangement of iron-based metallic ...

Generation and Control of Electrohydrodynamic Flows in Aqueous Electrolyte Solutions

水电解质溶液中 Electrohydrodynamic 流的产生与控制

To drive electrohydrodynamic (EHD) flows in aqueous solutions, the separation of cation and anion transport pathways is essential because a directed ...

Measurement of Dynamic Force Acted on Water Strider Leg Jumping Upward by the PVDF Film Sensor

PVDF 薄膜传感器对水黾腿跳起动力的测量

This study aimed to make an explanation for the phenomenon in nature that water strider usually jumps or glides on the water surface easily but quickly, ...