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1
Hauser, Janosch, Gustaf Kylberg, Mathieu Colomb-Delsuc, Göran Stemme, Ida-Maria Sintorn und Niclas Roxhed. „A microfluidic device for TEM sample preparation“. Lab on a Chip 20, Nr. 22 (2020): 4186–93. http://dx.doi.org/10.1039/d0lc00724b.
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We present a capillary-driven microfluidic single-use device that prepares a TEM grid with minimal user interaction. The user only initiates the sample preparation process, waits for about one minute and then collects the TEM grid, ready for imaging.
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Klebl, David P., Diana C. F. Monteiro, Dimitrios Kontziampasis, Florian Kopf, Frank Sobott, Howard D. White, Martin Trebbin und Stephen P. Muench. „Sample deposition onto cryo-EM grids: from sprays to jets and back“. Acta Crystallographica Section D Structural Biology 76, Nr. 4 (25.03.2020): 340–49. http://dx.doi.org/10.1107/s2059798320002958.
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Despite the great strides made in the field of single-particle cryogenic electron microscopy (cryo-EM) in microscope design, direct electron detectors and new processing suites, the area of sample preparation is still far from ideal. Traditionally, sample preparation involves blotting, which has been used to achieve high resolution, particularly for well behaved samples such as apoferritin. However, this approach is flawed since the blotting process can have adverse effects on some proteins and protein complexes, and the long blot time increases exposure to the damaging air–water interface. To overcome these problems, new blotless approaches have been designed for the direct deposition of the sample on the grid. Here, different methods of producing droplets for sample deposition are compared. Using gas dynamic virtual nozzles, small and high-velocity droplets were deposited on cryo-EM grids, which spread sufficiently for high-resolution cryo-EM imaging. For those wishing to pursue a similar approach, an overview is given of the current use of spray technology for cryo-EM grid preparation and areas for enhancement are pointed out. It is further shown how the broad aspects of sprayer design and operation conditions can be utilized to improve grid quality reproducibly.
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Basham, P. B., und H. L. Tsai. „Advanced TEM sample preparation techniques for submicron Si devices“. Proceedings, annual meeting, Electron Microscopy Society of America 53 (13.08.1995): 516–17. http://dx.doi.org/10.1017/s0424820100138956.
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The use of transmission electron microscopy (TEM) to support process development of advanced microelectronic devices is often challenged by a large amount of samples submitted from wafer fabrication areas and specific-spot analysis. Improving the TEM sample preparation techniques for a fast turnaround time is critical in order to provide a timely support for customers and improve the utilization of TEM. For the specific-area sample preparation, a technique which can be easily prepared with the least amount of effort is preferred. For these reasons, we have developed several techniques which have greatly facilitated the TEM sample preparation.For specific-area analysis, the use of a copper grid with a small hole is found to be very useful. With this small-hole grid technique, TEM sample preparation can be proceeded by well-established conventional methods. The sample is first polished to the area of interest, which is then carefully positioned inside the hole. This polished side is placed against the grid by epoxy Fig. 1 is an optical image of a TEM cross-section after dimpling to light transmission.
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Vinson, Phillip K. „The preparation and study of a holey polymer film“. Proceedings, annual meeting, Electron Microscopy Society of America 45 (August 1987): 644–45. http://dx.doi.org/10.1017/s0424820100127657.
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A holey carbon grid (HCG) consists of a TEM grid with a holey polymer film (HPF) attached to its surface and a carbon coating to provide mechanical stability and electrical conductivity. HCGs have found wide use in the preparation of liquid samples for cryo-TEM. These grids increase the number of sample sites by as much as three orders of magnitude and aid in the formation of fairly uniform, thin specimen films (< 250 nm). Several methods have been reported for the production of HPFs for specimen support. Unfortunately, most methods are unreliable, often producing films with pseudo-holes and large continuous film regions. Essential to improving any technique is an understanding of the process mechanisms involved. This paper describes a technique, modified from Refs. 1 and 2, for preparing HPFs and suggests a drying mechanism to explain the results.
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Tan, Yong Zi, und John L. Rubinstein. „Through-grid wicking enables high-speed cryoEM specimen preparation“. Acta Crystallographica Section D Structural Biology 76, Nr. 11 (13.10.2020): 1092–103. http://dx.doi.org/10.1107/s2059798320012474.
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Blotting times for conventional cryoEM specimen preparation complicate time-resolved studies and lead to some specimens adopting preferred orientations or denaturing at the air–water interface. Here, it is shown that solution sprayed onto one side of a holey cryoEM grid can be wicked through the grid by a glass-fiber filter held against the opposite side, often called the `back', of the grid, producing a film suitable for vitrification. This process can be completed in tens of milliseconds. Ultrasonic specimen application and through-grid wicking were combined in a high-speed specimen-preparation device that was named `Back-it-up' or BIU. The high liquid-absorption capacity of the glass fiber compared with self-wicking grids makes the method relatively insensitive to the amount of sample applied. Consequently, through-grid wicking produces large areas of ice that are suitable for cryoEM for both soluble and detergent-solubilized protein complexes. The speed of the device increases the number of views for a specimen that suffers from preferred orientations.
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Drulyte, Ieva, Rachel M. Johnson, Emma L. Hesketh, Daniel L. Hurdiss, Charlotte A. Scarff, Sebastian A. Porav, Neil A. Ranson, Stephen P. Muench und Rebecca F. Thompson. „Approaches to altering particle distributions in cryo-electron microscopy sample preparation“. Acta Crystallographica Section D Structural Biology 74, Nr. 6 (18.05.2018): 560–71. http://dx.doi.org/10.1107/s2059798318006496.
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Cryo-electron microscopy (cryo-EM) can now be used to determine high-resolution structural information on a diverse range of biological specimens. Recent advances have been driven primarily by developments in microscopes and detectors, and through advances in image-processing software. However, for many single-particle cryo-EM projects, major bottlenecks currently remain at the sample-preparation stage; obtaining cryo-EM grids of sufficient quality for high-resolution single-particle analysis can require the careful optimization of many variables. Common hurdles to overcome include problems associated with the sample itself (buffer components, labile complexes), sample distribution (obtaining the correct concentration, affinity for the support film), preferred orientation, and poor reproducibility of the grid-making process within and between batches. This review outlines a number of methodologies used within the electron-microscopy community to address these challenges, providing a range of approaches which may aid in obtaining optimal grids for high-resolution data collection.
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Mulligan, Sėan K., Jeffrey A. Speir, Ivan Razinkov, Anchi Cheng, John Crum, Tilak Jain, Erika Duggan et al. „Multiplexed TEM Specimen Preparation and Analysis of Plasmonic Nanoparticles“. Microscopy and Microanalysis 21, Nr. 4 (30.07.2015): 1017–25. http://dx.doi.org/10.1017/s1431927615014324.
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AbstractWe describe a system for rapidly screening hundreds of nanoparticle samples using transmission electron microscopy (TEM). The system uses a liquid handling robot to place up to 96 individual samples onto a single standard TEM grid at separate locations. The grid is then transferred into the TEM and automated software is used to acquire multiscale images of each sample. The images are then analyzed to extract metrics on the size, shape, and morphology of the nanoparticles. The system has been used to characterize plasmonically active nanomaterials.
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Rubinstein, John L., Hui Guo, Zev A. Ripstein, Ali Haydaroglu, Aaron Au, Christopher M. Yip, Justin M. Di Trani, Samir Benlekbir und Timothy Kwok. „Shake-it-off: a simple ultrasonic cryo-EM specimen-preparation device“. Acta Crystallographica Section D Structural Biology 75, Nr. 12 (22.11.2019): 1063–70. http://dx.doi.org/10.1107/s2059798319014372.
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Although microscopes and image-analysis software for electron cryomicroscopy (cryo-EM) have improved dramatically in recent years, specimen-preparation methods have lagged behind. Most strategies still rely on blotting microscope grids with paper to produce a thin film of solution suitable for vitrification. This approach loses more than 99.9% of the applied sample and requires several seconds, leading to problematic air–water interface interactions for macromolecules in the resulting thin film of solution and complicating time-resolved studies. Recently developed self-wicking EM grids allow the use of small volumes of sample, with nanowires on the grid bars removing excess solution to produce a thin film within tens of milliseconds from sample application to freezing. Here, a simple cryo-EM specimen-preparation device that uses components from an ultrasonic humidifier to transfer protein solution onto a self-wicking EM grid is presented. The device is controlled by a Raspberry Pi single-board computer and all components are either widely available or can be manufactured by online services, allowing the device to be constructed in laboratories that specialize in cryo-EM rather than instrument design. The simple open-source design permits the straightforward customization of the instrument for specialized experiments.
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Ashtiani, Dariush, Alex de Marco und Adrian Neild. „Tailoring surface acoustic wave atomisation for cryo-electron microscopy sample preparation“. Lab on a Chip 19, Nr. 8 (2019): 1378–85. http://dx.doi.org/10.1039/c8lc01347k.
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Surface acoustic wave (SAW) atomisation is investigated in the context of cryo electron microscopy grid preparation. Here, the primary requirements are a reproducible and narrow plume of droplets delivering a low fluid flow rate.
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Walker, John F. „TEM Sample Preparation for the Semiconductor Industry — Part 3“. Microscopy Today 4, Nr. 6 (August 1996): 24–25. http://dx.doi.org/10.1017/s1551929500060879.
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Part 1 of this series described how focused ion beam (FIB) microsurgery is used to successfully cross-section and prepare materialspecific samples for SEM and TEM analysis. In Part 2, we detailed how FIB is also the tool of choice to prepare site-specific samples, particularly for transmission electron microscopy (TEM) analysis. In this final article of this series, we describe actual sample preparation, cutting a selected area la size and mounting it on a grid for FIB preparation. Focused ion beams are very useful in preparing TEM specimens that have unique characteristics. In particular, the ability of such systems to image submicron features within a structure has allowed accurate identification of the precise place to make a membrane.
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Li, Du, Rose Zhou und Rob Zanoya. „Cross-Sectional Transmission Electron Microscopy Sample Preparation Using Focus Ion Beam Machine and Wedge Technique“. Microscopy and Microanalysis 5, S2 (August 1999): 894–95. http://dx.doi.org/10.1017/s1431927600017797.
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As features on an IC chip become smaller than the resolution power of an optical microscope and of the size of the grinding particles, the trend for preparing cross-sectional transmission electron microscopy (TEM) samples at specific locations (bits) is moving towards using a focused ion beam (FIB) machine. Details on how to use a FIB machine to prepare cross-sectional TEM samples have been outlined in many references.The general procedure is to first mark the specific location (bit) in the FIB machine and then grind the sample down to about 20 microns, 10 microns on each side of the feature of interest. After grinding, the sample is mounted on a pre-cut TEM grid and thinned with the FIB to about 0.1 micron in the region containing the feature of interest. There are several disadvantages to this method. First, the sample goes into the FIB machine at least twice—once for FIB marks on the location and once again for the final thinning.
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Wei, Hui, Venkat Dandey, Zhening Zhang, Ashleigh Raczkowski, Bridget Carragher und Clinton S. Potter. „Self-Blotting Nanowire Grids for Cryo-EM Sample Preparation“. Microscopy and Microanalysis 23, S1 (Juli 2017): 848–49. http://dx.doi.org/10.1017/s1431927617004901.
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AbstractAlmost every aspect of cryo electron microscopy (CryoEM) has been automated over the last few decades. One of the challenges that remains to be addressed is the robust and reliable preparation of vitrified specimens of suitable ice thickness. The development of a new self-blotting nanowire (Zhang et al., 2013) grid in conjunction with a piezo electric dispensing robot called Spotiton (Jain et al., 2012) enables spreading a sample to a thin film without the use of externally applied filter paper. This new approach has the advantage of using small amounts of protein material, resulting in large areas of ice of a well- defined thickness containing evenly distributed particles (Razinkov et al., 2016).
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Wang, Feng, Yanxin Liu, Zanlin Yu, Sam Li, Shengjie Feng, Yifan Cheng und David A. Agard. „General and robust covalently linked graphene oxide affinity grids for high-resolution cryo-EM“. Proceedings of the National Academy of Sciences 117, Nr. 39 (10.09.2020): 24269–73. http://dx.doi.org/10.1073/pnas.2009707117.
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Affinity grids have great potential to facilitate rapid preparation of even quite impure samples in single-particle cryo-electron microscopy (EM). Yet despite the promising advances of affinity grids over the past decades, no single strategy has demonstrated general utility. Here we chemically functionalize cryo-EM grids coated with mostly one or two layers of graphene oxide to facilitate affinity capture. The protein of interest is tagged using a system that rapidly forms a highly specific covalent bond to its cognate catcher linked to the grid via a polyethylene glycol (PEG) spacer. Importantly, the spacer keeps particles away from both the air–water interface and the graphene oxide surface, protecting them from potential denaturation and rendering them sufficiently flexible to avoid preferential sample orientation concerns. Furthermore, the PEG spacer successfully reduces nonspecific binding, enabling high-resolution reconstructions from a much cruder lysate sample.
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Walker, John F., James K. Odum und Peter D. Carleson. „Perfect TEM Membranes by focused ion beams: A stress reduction technique“. Proceedings, annual meeting, Electron Microscopy Society of America 54 (11.08.1996): 1030–31. http://dx.doi.org/10.1017/s0424820100167615.
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With the realisation that the critical dimensions in integrated circuits are shrinking to the point where scanning electron microscopy (SEM) techniques are not sufficiently accurate for many applications, advanced semiconductor fabs are looking to the increased resolution and analytical functionality of transmission electron microscopy (TEM) in failure and process analysis. TEM sample preparation is traditionally labour-intensive and needs skilled technical support but, with the acceptance of focused ion beam (FIB) workstations, this preparation and subsequent analysis is now becoming more routine. The reasons are: more reliable preparation with less risk of catastrophic breaking on unique specimens, highly site-specific preparation capable of viewing individual, sub-100 nm features, thin and uniform membranes even with tungsten plugs, and fast and easy preparation techniques.The initial stages of sample preparation involves preparing a sub-100 um sliver mounted on a TEM grid. When mounting this sliver on the grid, care must be taken to prevent any strain from being transferred to the silicon.
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Hassander, Helen. „Preparation Methods for EM Studies of Polymers“. Microscopy Today 20, Nr. 2 (28.02.2012): 46–49. http://dx.doi.org/10.1017/s1551929512000041.
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Polymers are organic materials, and most of the preparation methods for transmission electron microscopy (TEM) are much the same as for biological specimens. Bulk samples are cut in the ultramicrotome, and latex particles are dropped onto a Formvar-coated grid. However, the staining possibilities of polymers are limited. Polymers mainly consist of saturated hydrocarbon, and unlike biomaterial there are few reactive groups for staining. This has two consequences for the microscopist: it is difficult to obtain contrast, and the sample is very beam-sensitive. Biological samples are also organic material and sensitive to the beam, but the staining process converts them into materials that are usually stable to the beam.
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Rai, R. S., S. Bagchi, L. Duncan, L. Prabhu, J. Beck und J. Conner. „A Method for Preparation of Site-Specific Multiple Samples of Semiconductor Material for Transmission Electron Microscopy“. Microscopy and Microanalysis 7, S2 (August 2001): 948–49. http://dx.doi.org/10.1017/s1431927600030816.
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In recent years, the availability of focused ion beam (FIB) milling systems has given a much-needed boost for transmission electron microscopy (TEM) as a technique for site-specific analysis. Much progress has been made in the area of site-specific cross-sectional and planar TEM sample preparation techniques. However, a continuing need exists to reduce the sample preparation time, in order to improve TEM cycle time for better support of process development, yield improvement and production in a high-volume industrial environment. Thus, a faster TEM sample preparation technique is always desirable to meet this demand. A new approach to TEM sample preparation is described in this paper.Following the new approach developed in the present work, one can prepare on a single TEM grid at least two different cross-sectional samples of site-specific device structures or up to four different cross-sectional samples of blanket films. Two different samples, each containing an area of interest near the center, are cleaved or cut to a width of about 1.25 mm; these samples may be from two separate locations of a wafer, or from two different wafers where TEM analyses are required.
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Roussie, James. „New Ultra-Thin Pure Silicon Window Grids for Transmission Electron Microscopy Samples“. Microscopy Today 17, Nr. 2 (März 2009): 46–47. http://dx.doi.org/10.1017/s155192950005450x.
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Traditional sample preparation supports for electron microscopy have usually been thin films of amorphous or holey carbon stretched over a metallic grid. More recently introduced formats include organic polymers over metallic grids or silicon nitride and silicon oxide membranes over silicon frames. Here, the application of a nanofabricated silicon membrane technology as a novel sample preparation support for electron microscopy is described. These new supports offer several unique characteristics, including nanoscale thickness and pores, which may improve imaging and analysis of materials and biological molecules.Recently developed technology permits the fabrication of pure silicon membranes that are among the world's thinnest materials—only 5 to 15 nm thick. See Striemer et al., Nature (2007) 445: 749-751 for more details. These silicon membranes are also among the world's first membrane technologies to offer nanoscale pores of 5 to 50 nm. This combination of characteristics is unique and not shared by the materials currently employed as sample supports. Moreover, it suggests that these silicon membranes could overcome many of the problems associated with current generation materials. For example, the holes of lacey and holey carbon grids (1-5 micron diameter) are incompatible with the size of most nanotubes and nanoparticles (2-40 nm). Obtaining background-free images of the entire nanostructure is rarely possible with this incompatible combination of sizes. Another significant issue is the inability to vigorously plasma clean samples on carbon grids. In some cases, this inability to remove organic contaminants can prevent high-resolution imaging of samples.
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Roussel, Laurent. „Low-Energy Focused Ion Beam Milling Provides Reduced Damage During TEM Sample Preparation“. Microscopy Today 17, Nr. 5 (September 2009): 40–45. http://dx.doi.org/10.1017/s1551929509000364.
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The combined focused ion beam (FIB) and scanning electron microscope (SEM), known as the DualBeam, is well-known for its unique ability to produce site-specific thin samples starting from bulk and then attaching the section to a transmission electron microscope (TEM) grid, all in-situ. It has been reported that producing a thin sample using a 30 kV gallium FIB creates surface damage several tens of nanometers deep. However, recent DualBeam technology improvements now enable the FIB to produce thin samples with a thickness well below 50 nanometers and deliver a tightly focused ion beam at an energy of 2 kV and below, which dramatically reduces the damage depth to as low as 1 to 2 nanometers in typical materials, such as silicon.
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Taubert, Andreas, James H. Ferris und Karen I. Winey. „Rapid Preparation of a Polymer Fiber and a Free-Standing Polymer Film for Cross-Sectional Microtomy“. Microscopy Today 11, Nr. 4 (August 2003): 36–39. http://dx.doi.org/10.1017/s1551929500053062.
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Polymer films and fibers can readily be imaged in a “top-view“ mode by depositing the sample directly on a transmission electron microscopy (TEM) support grid. Sample preparation of thin polymer films and fibers for cross-sectional views in the electron microscope, however, is a major challenge. Owing to their small dimensions, the films or fibers cannot be mounted alone, because they will not remain immobilized In the microtome, even at low temperatures. Brittle polymers complicate sample preparation even further because they tend to break due to the mechanical stresses exerted on them by the microtome sample holder and the knife. Such sections often jump off the knife-edge or the sample film, thus preventing a systematic collection of thin sections. Similar arguments apply for cross-sectional atomic force microscopy (AFM).
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Chestnut, H., D. P. Siegel, J. L. Burns und Y. Talmon. „A temperature-jump technique for time-resolved cryo-transmission Electron Microscopy“. Proceedings, annual meeting, Electron Microscopy Society of America 47 (06.08.1989): 742–43. http://dx.doi.org/10.1017/s0424820100155682.
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Transmission electron microscopy of rapidly-frozen, hydrated specimens (cryo-TEM) is a powerful way of examining labile microstructures. This technique avoids some artifacts associated with conventional preparative methods. Use of a controlled environment vitrification system (CEVS) for specimen preparation reduces the risk of unwanted sample changes due to evaporation, and permits the examination of specimens vitrified from a defined temperature. Studies of dynamic processes with time resolution on the order of seconds, in which the process was initiated by changes in sample pH, have been conducted. We now report the development of an optical method for increasing specimen temperature immediately before vitrification. Using our method, processes that are regulated by temperature can be initiated in less than 500 msec on the specimen grid. The ensuing events can then be captured by plunge-freezing within an additional 200 msec.Dimyristoylphosphatidylcholine (DMPC) liposomes, produced by extrusion, were used as test specimens. DMPC undergoes a gel/liquid crystalline transition at 24°C, inducing a change in liposome morphology from polyhedral to spherical. Five-μl aliquots of DMPC dispersions were placed on holey-carbon-filmed copper grids mounted in the CEVS environmental chamber, and maintained at 6-8°C and 80% relative humidity. Immediately before the temperature jump most of the sample was blotted away with filter paper, leaving a thin specimen film on the grid. Upon pressing the trigger, an electronic control circuit generated this timed sequence of events. First, a solenoid-activated shutter was opened to heat the specimen by exposing it for a variable time to the focused beam of a 75W Xenon arc lamp. Simultaneously, a solenoid-activated cryogen shutter in the bottom of the CEVS was opened. Next, the lamp shutter was closed after the desired heating interval. Finally, a solenoid-activated cable release was used to trigger a spring-loaded plunger in the CEVS, propelling the sample into a reservoir of liquid ethane. Vitrified samples were subsequently transferred to a Zeiss EM902 TEM, operated in zero-loss brightfield mode, for examination at −163°C.
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Guglielmo, V., R. Saglia, F. J. Castander, A. Galametz, S. Paltani, R. Bender, M. Bolzonella et al. „Euclid preparation“. Astronomy & Astrophysics 642 (Oktober 2020): A192. http://dx.doi.org/10.1051/0004-6361/202038334.
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The Complete Calibration of the Colour–Redshift Relation survey (C3R2) is a spectroscopic effort involving ESO and Keck facilities designed specifically to empirically calibrate the galaxy colour–redshift relation – P(z|C) to the Euclid depth (iAB = 24.5) and is intimately linked to the success of upcoming Stage IV dark energy missions based on weak lensing cosmology. The aim is to build a spectroscopic calibration sample that is as representative as possible of the galaxies of the Euclid weak lensing sample. In order to minimise the number of spectroscopic observations necessary to fill the gaps in current knowledge of the P(z|C), self-organising map (SOM) representations of the galaxy colour space have been constructed. Here we present the first results of an ESO@VLT Large Programme approved in the context of C3R2, which makes use of the two VLT optical and near-infrared multi-object spectrographs, FORS2 and KMOS. This data release paper focuses on high-quality spectroscopic redshifts of high-redshift galaxies observed with the KMOS spectrograph in the near-infrared H- and K-bands. A total of 424 highly-reliable redshifts are measured in the 1.3 ≤ z ≤ 2.5 range, with total success rates of 60.7% in the H-band and 32.8% in the K-band. The newly determined redshifts fill 55% of high (mainly regions with no spectroscopic measurements) and 35% of lower (regions with low-resolution/low-quality spectroscopic measurements) priority empty SOM grid cells. We measured Hα fluxes in a 1.″2 radius aperture from the spectra of the spectroscopically confirmed galaxies and converted them into star formation rates. In addition, we performed an SED fitting analysis on the same sample in order to derive stellar masses, E(B − V), total magnitudes, and SFRs. We combine the results obtained from the spectra with those derived via SED fitting, and we show that the spectroscopic failures come from either weakly star-forming galaxies (at z < 1.7, i.e. in the H-band) or low S/N spectra (in the K-band) of z > 2 galaxies.
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Kunze, F., S. Kuns, T. Hülser, H. Wiggers und S. M. Schnurre. „Thermophoretic particle sampling on a TEM grid: A new design for sample preparation with high spatial accuracy“. Chemie Ingenieur Technik 92, Nr. 9 (28.08.2020): 1330. http://dx.doi.org/10.1002/cite.202055256.
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Fejeran, Adella, Jesus Polanco, Gabriel Lander, Teddy Ajero, Bridget Carragher und Clinton S. Potter. „TEM of Bacteriophages Found in Marine Sources“. Microscopy Today 15, Nr. 6 (November 2007): 28–31. http://dx.doi.org/10.1017/s1551929500061939.
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AbstractWe describe here a project to illustrate the diversity and abundance of marine bacteriophages undertaken by two high school students participating in The Scripps Research Institute's High School Student Research Education Program. The students were interns in the Automated Molecular Imaging group over the summer of 2007, during which time they acquired high magnification transmission electron microscopy images of bacteriophage filtered from samples collected from nearby marine waters. The basic protocols for sample collection, grid preparation, and electron microscopy imaging are described in this manuscript along with some of the images of the bacteriophages.
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Wilson, D., R. Valluzzi, T. Vuong, S.-J. Chien, S. P. Gido und D. Kaplan. „Solid State Conformational Transitions In Peptides Modeling B. Mori Fibroin“. Microscopy and Microanalysis 5, S2 (August 1999): 1216–17. http://dx.doi.org/10.1017/s1431927600019401.
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Fibrous proteins are molecules whose secondary structures are their dominant motifs due to their highly repetitive amino acid sequences. Most fibrous proteins have physiological roles as protective, connective or structural materials. Among the fibrous proteins, silks tend to have blocky structures, with crystallizable and amorphous blocks comprised of short, highly repetitive amino acid sequences. In addition, the high glycine content of silks allows them greater conformational variability than most proteins, thus Bombyx morisilk fibroin is typically polymorphic.The ability of silk fibroin to adopt multiple conformations and crystal structures makes it difficult to obtain corroborating data using multiple characterization techniques. Differences in sample preparation to accommodate different techniques can also affect the resulting sample structure. Reproducible sample preparation was achieved for IR and TEM experiments by rubbing the dried IR sample with a carbon substrate TEM grid to pick up tiny flakes of solidified peptide.
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Frankel, Cynthia L., und Aileen L. Fink. „Disaster Preparation Planning: In Industry“. AAOHN Journal 35, Nr. 1 (Januar 1987): 32–40. http://dx.doi.org/10.1177/216507998703500106.
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Sixty-eight disaster planners in manufacturing companies from the state of Washington provided information pertaining to their disaster planning practices by completing a mailed questionnaire. A checklist-grid format of nineteen emergency care procedures was presented to respondents with four questions asked in relation to each procedure. Less than half of the sample reported that the protocols are utilized in written plans, disaster drills or educational procedures. Thirty-five percent of the respondents indicated that no internal accountability exists for all of the 19 procedures. Ten percent to thirty percent of the sample of respondents reported that no internal or external accountability exists for all of the 19 procedures. Respondents reported that disaster drills and real disaster events rarely occur within the time interval of a year; less than ten percent of the respondents have drills or real events in a year for each of the protocols. Twenty-five percent to forty-five percent of the respondents reported they do not have education and teaching for each of the disaster procedures and protocols. The majority of respondents (54.4%) had no education in disaster planning as well. The data show that large- and medium-sized rather than small-sized companies more frequently utilize disaster preparedness strategies including written plans and disaster drills. Twenty-one (approximately 30%) of the respondents out of a total of 68 stated that their companies engaged in post-drill evaluations and critiques. Nineteen out of 68 respondents modify their written plans following the disaster critique. The protocols for which occupational health nurses mainly play a primary role include employee safety and first aid, employee information/awareness, and lead in emergency shelter and employee care. However, the 68 respondents recognized occupational health nurses as participants at a ten % or less rate. The extent to which implementation of disaster procedures was based on written protocol guidelines and educational training or mandated by internal accountability was difficult to determine from the data due to the dissimilarity of the sample. These data, however, suggest that disaster protocol usage is not a widely established practice for this sample of disaster planners.
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Ultee, Eveline, Fred Schenkel, Wen Yang, Susanne Brenzinger, Jamie S. Depelteau und Ariane Briegel. „An Open-Source Storage Solution for Cryo-Electron Microscopy Samples“. Microscopy and Microanalysis 24, Nr. 1 (18.01.2018): 60–63. http://dx.doi.org/10.1017/s143192761701279x.
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AbstractCryo-electron microscopy (cryo-EM) enables the study of biological structures in situ in great detail and to solve protein structures at Ångstrom level resolution. Due to recent advances in instrumentation and data processing, the field of cryo-EM is a rapidly growing. Access to facilities and national centers that house the state-of-the-art microscopes is limited due to the ever-rising demand, resulting in long wait times between sample preparation and data acquisition. To improve sample storage, we have developed a cryo-storage system with an efficient, high storage capacity that enables sample storage in a highly organized manner. This system is simple to use, cost-effective and easily adaptable for any type of grid storage box and dewar and any size cryo-EM laboratory.
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Nagahama, Hideo De Jesus, Jorge Wilson Cortez, Wisy Alves Pimenta, Antonio Pereira Patrocinio Filho und Elder Barboza de Souza. „Resistência do solo à penetração em sistemas de preparo e velocidades de deslocamento do trator“. Comunicata Scientiae 7, Nr. 1 (10.05.2016): 56. http://dx.doi.org/10.14295/cs.v7i1.439.
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The continuous use of tillage equipment without variation of the work depth can lead to soil compression problems. This study aimed to evaluate the spatial variability of soil resistance to penetration (RP) in a yellow ultisol profile in different tillage systems and tractor-equipment speeds. The experiment was carried out at the Agricultural Sciences Campus – UNIVASF, Petrolina- PE, Brazil, in randomized blocks with split plot with four repetitions. The treatments consisted of five tillage systems applied to the plots: without the first soil preparation, tandem grid and moldboard plow, 0.56 m off-set grid discs, 0.61 m off-set grid disc plus tandem grid and chisel plow. For the subplots, the speeds of the tractor-equipment used were: 2.45 km h‑1 (L1), 3.88 km h-1 (L2), 5.72 km h-1 (L3) and 6.50 km h-1 (H1). For the soil data collection and the RP determination, an electronic penetrometer was used, determining the sample profile moisture. Data analysis was carried out based on geostatistics and isoline maps. It can be verified the operationarea of the active organs of the equipment, the zoning of compacted areas (RP) and the RP levels of the studied profile. The lower RP was obtained when the tandem grid plus the chisel plow was used.
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Kim, Yeong K., und Do Soon Hwang. „Analyses of PBGA Packaging under Strong Vibration“. International Symposium on Microelectronics 2014, Nr. 1 (01.10.2014): 000488–92. http://dx.doi.org/10.4071/isom-wa44.
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Experimental and numerical analyses on the solder joint reliability of plastic ball grid array under harsh random vibration were presented. The chips were assembled on the daisy chained circuit boards for the test samples preparation, and a half of the samples were processed for underfill to investigate the underfill effects on the solder failures. Two consequential steps of the random vibrations, named as acceptance and qualification levels, were applied. Overall controlled RMS of the power spectrum densities of the steps were 22.7 Grms and 32.1 Grms, respectively. It was found that the samples did not show any solder failure during the tests, demonstrating the robustness of the packaging structure for potential avionics and space applications. Finite element analyses were performed to calculate the sample vibration behaviors and the solder stresses, and the results were compared with the test data.
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Stevie, F. A., C. B. Vartuli, R. H. Mills, R. B. Irwin, T. L. Shofner und L. A. Giannuzzi. „The FIB Lift-Out Specimen Preparation Technique for TEM Analyses and Beyond: SEM, AUGER, STEM, and SIMS Applications“. Microscopy and Microanalysis 5, S2 (August 1999): 888–89. http://dx.doi.org/10.1017/s1431927600017761.
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The use of focused ion beams (FIB) to prepare site specific specimens for transmission electron microscopy (TEM) and scanning electron microscopy (SEM) has been well documented. The 5 to 7 nm resolution on the latest FIB instruments has enhanced the ability to locate and expose features of interest. The use of the lift-out technique of FIB specimen preparation removes the need for prior thinning of the sample for TEM analysis and permits the study of materials that were difficult or impossible to do previously. Use of high current (10 nA) FIB instruments makes specimen preparation possible in less than one hour; automatic operation of FIB instruments will further reduce this time. After milling in the FIB, specimens are micromanipulated in air onto a 3 mm diameter TEM sample grid coated with carbon. The ability to analyze lift-out specimens using other analytical techniques that can take advantage of this site specific capability was previously suggested.
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Giannuzzi, Lucille A., Richard Young und Pete Carleson. „Using a Focused Ion Beam (FIB) System to Extract TEM-Ready Samples from Complex Metallic and Ceramic Structures“. Microscopy Today 7, Nr. 2 (März 1999): 12–15. http://dx.doi.org/10.1017/s1551929500063860.
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AbstractDriven by the analytical needs of microelectronics, magnetic media and micro-fabrication industries, focused ion beam (FIB) systems are now capable of milling and manipulating samples for the analysis of microstructure features having dimensions of 180 nm or less, A technique for locating and extracting site specific specimens for examination by transmission electron microscopy (TEM) has been developed. An identified feature can be located and precisely milled with an FIB system from two sides to prepare an ultrathin sample, and then extracted from the region with a glass rod micromanipulator onto a grid for TEM analysis. This specimen preparation method has been applied to semiconductor failure analysis and to the study of metallic and ceramic microsiructures with irregular topographies and complex mufti-layered components.
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Talmon, Y., J. L. Burns, M. H. Chestnut und D. P. Siegel. „On-the-Grid Processing and Time-Resolved Cryo-TEM: The Extension of the Thin Liquid Film Vitrification Method“. Proceedings, annual meeting, Electron Microscopy Society of America 48, Nr. 1 (12.08.1990): 490–91. http://dx.doi.org/10.1017/s0424820100181208.
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The thin vitrified liquid film technique was pioneered by Dubochet and co-workers. The technique is based on forming a thin liquid film of the system to be examined over a holey carbon film, and plunging it, using a mechanical plunger, into liquid ethane at its freezing point. Talmon and co-workers have developed the controlled environment vitrification system (CEVS), that makes it possible to prepare the sample under controlled conditions of temperature and saturation with volatiles. This has extended the applicability of the technique to labile systems that are sensitive to temperature and concentration changes, and to the study of microstructures that exist above (up to 95 °C), and below (down to −20 °C) room temperature. Here we discuss two extensions to cryo-TEM specimen preparation by thin fluid film vitrification, both based on specimen preparation in the CEVS: on-the-grid processing and time-resolved cryo-transmission electron microscopy.
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Rossie, B. B., T. L. Shofner, S. R. Brown, S. D. Anderson, M. M. Jamison und F. A. Stevie. „A Method for Thinning FIB Prepared TEM Specimens after Lift-Out“. Microscopy and Microanalysis 7, S2 (August 2001): 940–41. http://dx.doi.org/10.1017/s1431927600030774.
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Advantages of the FIB lift-out technique over traditional H-bar TEM specimen preparation have been recognized. The ability to rapidly (< 1 hour) prepare a site specific TEM specimen without destroying the entire bulk specimen has led to a wide spread reliance on this method. The main disadvantage of this technique is an inability to accomplish additional membrane thinning if required. Traditional H-bar preparation allows additional thinning. However, mechanical polishing is time consuming and the bulk sample is destroyed. A method has been developed which combines the efficient, site specific advantages of the lift-out method with the H-bar's ability to accomplish additional thinning. in this procedure a lift-out specimen is removed from the bulk sample and mounted onto a half-grid in a configuration similar to that employed by the H-bar technique.A 1.0-micron thick lift-out specimen was prepared using a FEI Strata DB-235 FIB dual-beam workstation by sputtering away bulk material leaving a thin membrane containing a desired feature (FIG 1).
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Son, Won-Su, Tae Jun Yoon, Hee Jeong Park, Minsoo Kim, Tadafumi Adschiri und Youn-Woo Lee. „A novel sample preparation method on CeO2 nanoparticles with TEM grid embedded liquid CO2 displacement and supercritical CO2 drying for microscopic analysis“. Journal of Supercritical Fluids 152 (Oktober 2019): 104559. http://dx.doi.org/10.1016/j.supflu.2019.104559.
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Xu, Youren, Chris Schwappach und Ron Cervantes. „Precision TEM Specimen Preparation for Integrated Circuits using Dual-Beam FIB Lift-Out Technique“. Microscopy and Microanalysis 6, S2 (August 2000): 516–17. http://dx.doi.org/10.1017/s1431927600035078.
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Focused ion beam lift-out technique has become increasingly attractive to the TEM community due to its unique advantage of no mechanical grinding/polishing involved in the process [1-3]. The technique essentially consists of two parts: preparation of membrane using focused ion beam (FIB) and transfer of the membrane (lift-out) to a grid. Up to date, this technique has only been demonstrated on single beam FIB systems. From a practical standpoint, overall sample quality (thickness) and lack of end-point precision are two major issues associated with the conventional single beam FIB technique. These issues are primarily related to ion beam damage and endpoint control encountered during the final stages of specimen thinning. As a result, the widespread use of FIB lift-out technique for high precision TEM specimen preparation has been limited. Recent technological advances have made it possible to combine both an electron beam column and an ion beam column into an integrated dual beam-focused ion beam (DB-FIB) system.
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Bovin, J. O., T. Huber, O. Balmes, J. O. Malm und G. Karlsson. „Jump Ratio Elemental Mapping in Amorphous Ice Cryo-EFTEM Opens the Window to Solution Chemistry“. Microscopy and Microanalysis 5, S2 (August 1999): 644–45. http://dx.doi.org/10.1017/s1431927600016548.
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The preparation of frozen amorphous thin films of solutions containing crystals, and imaging with cryo energy filtered TEM, opens for the first time the possibility to image the chemistry of solids interacting with liquids. The future possible areas of research include: dynamic of crystal growth processes, adsorption mechanisms, ion exchange, structure determination of solids in equilibrium with solutions, etc.The sample preparation uses a controlled-environment vitrification system1. Vitrification of the liquid phase was achieved by plunging the grid into liquid ethane. The vitrified specimen was transferred into the microscope by an Oxford CT3500 cryo-holder. The specimen temperature in the microscope column can be kept at -−183 °C. The thickness of the vitrified films, including the crystals, should be about 250 nm or preferably less. The Philips CM120 BioTWIN Cryo, here used for cryo-TEM, has a focal length of 6 mm and a structural resolution of 0.4 nm.
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Ilginis, Arminas, und Egidijus Griškonis. „Modification of Graphite Felt with Lead (II) Formate and Acetate—An Approach for Preparation of Lightweight Electrodes for a Lead-Acid Battery“. Processes 8, Nr. 10 (02.10.2020): 1248. http://dx.doi.org/10.3390/pr8101248.
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Lead-acid battery (LAB) weight is a major downside stopping it from being adapted to electric/hybrid vehicles. Lead grids constitute up to 50% of LAB electrode’s weight and it only ensures electric connection to electrochemically active material and provides structural integrity. Using graphite felt (GF) as a current collector can reduce the electrode’s weight while increasing the surface area. Modification of GF with lead (II) oxide using impregnation and calcination techniques and lead (II) formate and acetate as precursors was conducted to produce composite electrodes. It was found that lead (II) formate is not a viable material for this purpose, whereas multiple impregnation in lead (II) acetate saturated solution and calcination in air leads to thermal destruction GF. However, impregnation and calcination under nitrogen atmosphere in three cycles produced a sample of good quality with a mass loading of lead (II) oxide that was 17.18 g g−1 GF. This equates to only 5.5% of the total mass of composite electrode to be GF, which is immensely lower than lead grid mass in traditional electrodes. This result shows that a possible lightweight alternative of LAB electrode can be produced using the proposed modification method.
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SHARPE, A. N., E. M. HEARN und J. KOVACS-NOLAN. „Comparison of Membrane Filtration Rates and Hydrophobic Grid Membrane Filter Coliform and Escherichia coli Counts in Food Suspensions Using Paddle-Type and Pulsifier Sample Preparation Procedures“. Journal of Food Protection 63, Nr. 1 (01.01.2000): 126–30. http://dx.doi.org/10.4315/0362-028x-63.1.126.
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Food suspensions prepared by Pulsifier contained less debris and filtered 1.3× to 12× faster through hydrophobic grid membrane filters (HGMFs) than those prepared by Stomacher 400. Coliform and Escherichia coli counts made by an HGMF method yielded 84 and 36 paired samples, respectively, positive by both suspending methods. Overall counts of pulsificates and stomachates did not differ significantly for either analysis, though coliform counts by Pulsifier were significantly higher in mushrooms and significantly lower in ground pork (P = 0.05). Regression equations for log10 counts of coliform and E. coli by Pulsifier and Stomacher were: Pulsifier = 0.12 + 0.97 × Stomacher, and Pulsifier = 0.01 + 1.01 × Stomacher, respectively.
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Felsmann, Michael, und Max T. Otten. „Automated asbestos analysis with Philips CM microscopes“. Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 512–13. http://dx.doi.org/10.1017/s0424820100170293.
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The analysis of asbestos fibres is well established (see 1 for a description of the preparation and the procedure for detection and fibre characterisation with a transmission microscope). Although the procedure for fibre counting and characterisation is described in detail, the result depends on the accuracy of the time-consuming and tedious sample inspection. A substantial part of operator effort is wasted on scanning the grid in the right way in order to avoid double counting of fibres or missingareas. In this way a subjective factor may contribute to the measurement and can distort the results.In order to make asbestos analysis more reliable, a remote control program has been developed for the motorised goniometers of the Philips CM series microscopes (the CompuStage of the recently introduced Cmxxx series or the Specimen Relocation System of the previous Cmxx series). The program controls the systematic scanning of the grid and documentation of the fibres detected. In this way the operator can concentrate fully on the inspection and characterisation of the fibres.
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Balmes, O., und J. O. Bovin. „Cryo-TEM Observation of 3-D Ordered Aggregates of 5-nm Gold Clusters in Solutions“. Microscopy and Microanalysis 7, S2 (August 2001): 396–97. http://dx.doi.org/10.1017/s1431927600028051.
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The preparation of frozen amorphous nano-meter thin films of solutions containing particles, and imaging with cryo- TEM, opens for the first time the possibility to study cluster assembles interacting with liquids. The method is here used to show evidence for assembly of ordered 3-dimensional aggregates of ligand stabilized 5-nm gold clusters in a long chain alcohol solution. The use of the plunge-freezing method allows freezing of solutions at a cooling rate that does not allow re-organization of the clusters. The stability of the amorphous solid solutions under the electron beam make it possible to record several pictures of the same aggregate at different angles and clearly identify the super-structure.The sample preparation uses a modified controlled-environment vitrification system built in glass. Solidification of the liquid phase was achieved by plunging the solution, suspended in the holes of a lacy carbon on a copper grid, into liquid ethane (-174 °C) or in some cases liquid nitrogen.
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Balzuweit, Karla, Thais MIlagres, Von Braun Nascimento, Vagner de Carvalho, Edmar Soares und Luiz Ladeira. „LEED and TEM analysis of Bismuth Telluride“. Acta Crystallographica Section A Foundations and Advances 70, a1 (05.08.2014): C194. http://dx.doi.org/10.1107/s2053273314098052.
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Bismuth Telluride has recently been identified as a 3D-topological insulator [1] as well as Graphene [2]. Topological insulators are a quite recent discovered quantum mechanics characteristic of materials where essentially the surface band structure is completely different from the bulk. Bismuth Telluride, for example has its semi-metallic behavior changed into a conducting one. However it has been well known, as an excellent thermoelectric material [3]; with relatively high thermoelectric coefficients at room temperature. Bismuth Telluride is a relatively easy material to obtain and different compositions are being studied both as bulk material and as thin films. Crystals of Bi2Te3 were Bridgman grown in a sealed quartz ampoule in a directional resistance oven at a temperature of 600oC. Conventional X-ray Laue diffraction showed patterns compatible with a single crystal along the sample except for the starting point, which was discarded. Transmission and Scanning Electron Microscopy and Low Energy Electron Diffraction (LEED) were performed. The grown crystals were cleaved and small parts were crushed on a mortar with ethanol and deposited onto a holey carbon grid. Also thin slices were cut in an ultramicrotome (Leica UC6) with a diamond knife and deposited onto a holey carbon coated grid. TEM measurements showed the presence of grains on both samples with a very small deviation from the observed crystallographic axis (0001). However LEED measurements showed only a single crystalline pattern. Electron backscatter diffraction (EBSD) studies showed large granular areas with a extremely small angular variation between the grains. It is still unclear if those differences are real or due to sample preparation artifacts and effort is being put into analyzing exactly the same piece with all the different techniques.
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Wang, Haiyan. „Rapid Methods for Detection and Enumeration of Campylobacter spp. in Foods“. Journal of AOAC INTERNATIONAL 85, Nr. 4 (01.07.2002): 996–99. http://dx.doi.org/10.1093/jaoac/85.4.996.
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Abstract Campylobacter spp. are the most commonly reported bacterial cause of acute diarrheal disease in humans throughout the world. Traditional cultural methods for the detection and quantitation of Campylobacter spp. are slow and tedious; therefore, specific, sensitive, and rapid methods for campylobacters are needed to collect sufficient data for risk assessment and food safety policy development. We developed several rapid methods based on polymerase chain reaction (PCR), DNA hybridization, hydrophobic grid membrane filters (HGMFs), and enzyme immunoassays (EIAs). A PCR assay targeting C. jejuni, combined with a simple sample preparation procedure, detects as few as 0.3 most probable number (MPN)/mL C. jejuni in naturally contaminated chicken rinses after 20–24 h enrichment. An HGMF–EIA method using a commercial polyclonal antibody for Campylobacter detects and enumerates thermophilic Campylobacter spp. from spiked chicken rinse and milk, and naturally contaminated chicken rinses. A C. jejuni–specific probe in an HGMF–DNA hybridization protocol specifically detects and quantitates C. jejuni in food samples. A dot-blot EIA combined with an MPN procedure quantitates thermophilic campylobacters from samples that might be difficult to filter through HGMFs.
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Li, Wenbin, Yong Wang, Yanting Feng, Qing Wang, Xuexia Xu, Guowei Li, Guozhen Dong et al. „A Cost-Effective Method for Preparing Robust and Conductive Superhydrophobic Coatings Based on Asphalt“. Scanning 2020 (24.12.2020): 1–8. http://dx.doi.org/10.1155/2020/5642124.
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The wide application of superhydrophobic materials is mainly hindered by the poor mechanical robustness and complicated preparation method. To overcome these problems, we tried to make a combination of hierarchical and self-similar structure by the means of a simple spraying method. By adding nanofiller (carbon nanotube) and microfiller (graphite powder and expanded graphite), the hierarchical structure was constructed. By further doping the fillers in the commercial asphalt uniformly, the self-similar structure was prepared. Based on the aforementioned work, the as-prepared sample could withstand the sandpaper abrasion for 12.00 m under 4.90 kPa. Moreover, this superhydrophobic coating demonstrated good conductivity, superior self-cleaning property, and excellent corrosion resistance. The integration of conductivity with the superhydrophobicity might open new avenues for ground grid applications.
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Bovin, J. O. „EFTEM Elemental Mapping of Particles Frozen in Amorphous Solutions“. Microscopy and Microanalysis 6, S2 (August 2000): 2–3. http://dx.doi.org/10.1017/s1431927600032505.
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The preparation of frozen amorphous nano-meter thin films of solutions containing particles, and imaging with energy filtered TEM, opens for the first time the possibility to map the elemental distribution in solids interacting with liquids. The future possible areas of research in solution include: dynamic of crystal growth processes, adsorption mechanisms, ion exchange, structure determination of nano-sized solids in equilibrium with different solvents, etc.The sample preparation uses a controlled-environment vitrification system. Solidification of the liquid phase was achieved by plunging the solution, suspended in the holes of a lacy carbon on a copper grid, into liquid ethane (-174 °C). The specimen was transferred into the microscope by an Oxford CT3500 cryo-holder. The specimen temperature in the microscope column can be kept at -183 °C. The thickness of the vitrified film's, including the particles, should be about 50-100 nm or preferably less. The Philips CM120 BioTWIN Cryo microscope, here used for cryo-EFTEM, has a focal length of 6 nun and a structural resolution of 0.4 nm.
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Wu, Liwei, Jing Wang, Qian Jiang, Zhenqian Lu, Wei Wang und Jia-Horng Lin. „Low-velocity impact behavior of flexible sandwich composite with polyurethane grid sealing shear thickening fluid core“. Journal of Sandwich Structures & Materials 22, Nr. 4 (25.03.2019): 1274–91. http://dx.doi.org/10.1177/1099636219837701.
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In this study, a new type of flexible sandwich composite with nonwoven facesheets and core reinforced by polyurethane (PU) grid sealing shear thickening fluid (STF) has been presented. With the specific design, the STF was sealed into PU grids as the core to provide shear thickening effect against impact. Rheological property of STF with different mass ratio and PU morphology after first and second foaming were evaluated and optimized for sandwich composite preparation. Both static compression and dynamic impact tests were carried out to obtain the impact dynamic response and investigate the effects of typical parameters including STF volume, core thickness and striker height on low-velocity impact behavior. The test results showed that the optimal concentration of STF was 20 wt.%, whose critical shear rate was 100s−1. The presence of STF had a positive influence on the static compression strength and dynamic impact strength. In particular, the 70% STF volume fraction contributed to the highest compression modulus. The compression modulus was 445 MPa and 466 MPa when the sample thickness was 2 cm and 3 cm, respectively. As for dynamic impact strength with corresponding STF volume fractions, it was 4535.31 mJ for 30%, 4599.72 mJ for 50%, and 4827.46 mJ for 70%, all of which were much higher than that (2348 mJ) of control group (without STF). Regardless of whether the STF volume being 30%, 50% and 70%, the impact displacement of composite was within 10 mm, showing better impact resistance than control group (13.16 mm). Besides, this composite with special PU grid sealing, STF structure demonstrated a certain strain rate effect. The higher the impact energy, the greater the energy absorption was. Specifically, impact energy absorption rate of composite with a thickness of 3 cm was as high as 52.3% under 350 mm impact height.
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Kanemaru, Takaaki, Teruyoshi Kondo, Kei-ichiro Nakamura, Hiroyuki Morimoto, Kentaro Nishi und Shin-ichiro Isobe. „A simple preparation method for CLEM using pre-embedding immunohistochemistry with a novel fluorescent probe and stable embedding resin“. Microscopy 70, Nr. 4 (22.01.2021): 368–74. http://dx.doi.org/10.1093/jmicro/dfab005.
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Abstract Correlative light and electron microscopy (CLEM) is an excellent approach for examining the cellular localization of biomolecules. Here, we developed a simple method for CLEM by combining pre-embedding immunohistochemistry with a novel fluorescent probe, namely Fluolid NS Orange, and an embedding resin called ʻDurcupan™ʼ. Specimens were embedded in Durcupan™ or LR White after immunolabeling and post-fixation using glutaraldehyde and osmium tetroxide. Next, ultrathin sections were prepared on a finder grid with navigation markers. The section of the specimen embedded in Durcupan™ was found to be more stable against electron beam irradiation than specimens embedded in LR White. A fluorescence light microscopy image and a transmission electron microscopy (TEM) image, at wide-field, and low magnification, were independently obtained with the same ultrathin section. Using the three corners between finder grid bars as landmarks, fluorescence light microscopy images were superimposed with wide-field, low-magnification TEM images to identify the region of interest, which was subsequently enlarged to ascertain cellular structures localized beneath fluorescent signals. However, the enlarged TEM images appeared blurred, and fluorescence signals had a hazy appearance. To resolve this, the enlarged TEM images were replaced by high-resolution TEM images focused directly on the region of interest, thereby facilitating the collection of high-resolution CLEM images. The simple sample processing method for CLEM using osmium-resistant Fluolid NS Orange and electron beam damage-resistant Durcupan™ allowed the determination of the precise localization of fluorescence signals at subcellular levels.
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Wheatley, Rachael, und Daria J. Kuss. „Researcher-practitioner reflections: the therapeutic utility of the visually adapted repertory grid technique (VARGT) with stalkers“. Journal of Forensic Practice 22, Nr. 2 (25.03.2020): 97–108. http://dx.doi.org/10.1108/jfp-09-2019-0041.
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Purpose This paper outlines researcher–practitioner reflections on the use of a visually adapted repertory grid technique (VARGT) with men convicted of stalking. It draws on and assimilates participant experiences of the VARGT as a research engagement tool. Further, it extends discussion to propose its value as a generic engagement tool for when personal insights and collaborative case formulations may otherwise be difficult to access. Design/methodology/approach The repertory grid technique, developed from Kelly’s Personal Construct Theory (1955), was adapted visually for utility in a mixed methods research study with those who commit stalking offences (Wheatley, in preparation). Analytical and reflexivity processes within this original study highlighted rich and recurrent data across the sample pertaining to the positive participant experience of the VARGT, unrelated to its core research question. Findings This paper presents reflections and psychological discussion for experiences of using the VARGT. Key features clustered around therapeutic alliance and engagement, enlightenment and a motivation for positive change. Practical implications This paper suggests the VARGT has value in participant–client engagement, particularly where sensitive topics are being investigated and participants have difficulty directly articulating their psychosocial functioning. Originality/value This novel technique offers potential as an engagement tool for use in research and clinical settings.
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Ogden, Gordon J. „Pollen analysis: state of the art“. Géographie physique et Quaternaire 31, Nr. 1-2 (09.12.2010): 151–59. http://dx.doi.org/10.7202/1000061ar.
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Although nearly 50 years have passed since P.B. Sears introduced pollen analysis to North America, it remains an occult art. Dramatic improvements in sampling and analytic techniques continue to be limited by intractable problems of differential production, dispersal, ballistics, sedimentation, and preservation. It is a basic tenet of pollen stratigraphy that the data set, consisting primarily of microfossils preserved in sediments, is better than anything we have yet been able to do with it. Basic agreement between late- and postglacial pollen records has been confirmed wherever the method has been applied. Quantitative sampling techniques, sample preparation, and analytic procedures, together with multiple radiocarbon dates, permits calculation of sedimentation rates and absolute pollen influx. Of approximately 300 sediment cores from northeastern North America, fewer than 30 have more than 3 radiocarbon determinations from which least squares power curve regressions can be reliably calculated in the determination of sedimentation rates. Analogy with modern environments represented by surface pollen spectra is limited by an insufficient number of samples of uniform quality to characterize a vegetational mosaic covering 40 degrees of latitude (40-80°N) and longitude (60-100°W). The present surface pollen data bank includes about 700 samples, unevenly spaced and of uneven quality, permitting a grid resolution of no better than 10,000 km2.
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Sieber, H., D. R. Allen und J. Perepezko. „Microstructure Characterization of Ni-V Splat Quenched Foils“. Microscopy and Microanalysis 3, S2 (August 1997): 694–95. http://dx.doi.org/10.1017/s1431927600010357.
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Although the thickness of splat quenched (SQ) foils is normally less then 100 μm the solidified microstructure is usually not homogenous, but rather is determined by a cooling rate dependent nucleation and growth behavior of the different phases. The cooling rate and thus the microstructure changes significantly with distance from the edge to the middle of the SQ foils. Rapidly quenched nickel-vanadium (Ni-V) foils consist of three phases formed during solidification, a Ni-fcc, a V-bcc and a intermetallic σ phase [1-3]. To interpret the microstructure evolution in detail, a special TEM cross section sample preparation was applied. The SQ foil was ground to 30 μm, glued on a copper grid and ion-milled parallel to the foils (Fig.1a). In Ni-49V SQ foils seven typical microstructure regions (see Fig. 1 b) could be identified and were analyzed in detail by TEM investigations in plan view and cross section geometries. Furthermore, three solidification pathways were identified.
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Shaffer, O. L., M. S. El-Aasser, C. L. Zhao, M. A. Winnik und R. R. Shivers. „Cryomicroscopy of multiphase latices“. Proceedings, annual meeting, Electron Microscopy Society of America 49 (August 1991): 1060–61. http://dx.doi.org/10.1017/s0424820100089615.
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Transmission electron microscopy is an important approach to the characterization of the morphology of multiphase latices. Various sample preparation techniques have been applied to multiphase latices such as OsO4, RuO4 and CsOH stains to distinguish the polymer phases or domains. Radiation damage by an electron beam of latices imbedded in ice has also been used as a technique to study particle morphology. Further studies have been developed in the use of freeze-fracture and the effect of differential radiation damage at liquid nitrogen temperatures of the latex particles embedded in ice and not embedded.Two different series of two-stage latices were prepared with (1) a poly(methyl methacrylate) (PMMA) seed and poly(styrene) (PS) second stage; (2) a PS seed and PMMA second stage. Both series have varying amounts of second-stage monomer which was added to the seed latex semicontinuously. A drop of diluted latex was placed on a 200-mesh Formvar-carbon coated copper grid.
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Wang, Naixiao, Xilin Wang, Ping Chen, Zhidong Jia, Liming Wang, Ronghui Huang und Qishen Lv. „Metal Contamination Distribution Detection in High-Voltage Transmission Line Insulators by Laser-induced Breakdown Spectroscopy (LIBS)“. Sensors 18, Nr. 8 (10.08.2018): 2623. http://dx.doi.org/10.3390/s18082623.
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The fast detection of classical contaminants and their distribution on high-voltage transmission line insulators is essential for ensuring the safe operation of the power grid. The analysis of existing insulator contamination has traditionally relied on taking samples during a power cut, taking the samples back to the lab and then testing them with elemental analysis equipment, especially for sugars, bird droppings, and heavy metal particulates, which cannot be analysed by the equivalent salt deposit density (ESDD) or non-soluble deposit density (NSDD) methods. In this study, a novel method called laser-induced breakdown spectroscopy (LIBS) offering the advantages of no sample preparation, being nearly nondestructive and having a fast speed was applied for the analysis of metal contamination. Several LIBS parameters (laser energy and delay time) were optimized to obtain better resolution of the spectral data. The limit of detection (LOD) of the observed elements was obtained using a calibration curve. Compared to calibration curves, multivariate analysis methods including principal component analysis (PCA), k-means and partial least squares regression (PLSR) showed their superiority in analyzing metal contamination in insulators. Then, the elemental distribution of natural pollution was predicted using LIBS to fully capture information about the bulk elements (Na, Ni, Cu, Mn, Ca, etc.) of entire areas with PLSR. The results showed that LIBS could be a promising method for accurate direct online quantification of metal contamination in insulators.