Standardization microscopy

Scanning transmission electron microscopy (STEM) is a standard microscopy technique that images single atoms with a tightly focused beam [SOUtll]. The same restrictions apply as for STM, with the additional constraint that only fairly heavy atoms (e.g., uranium) can be successfully imaged. 

Two nucleation processes important to many people (including some surface scientists ) occur in the formation of gallstones in human bile and kidney stones in urine. Cholesterol crystallization in bile causes the formation of gallstones. Cryotransmission microscopy (Chapter VIII) studies of human bile reveal vesicles, micelles, and potential early crystallites indicating that the cholesterol crystallization in bile is not cooperative and the true nucleation time may be much shorter than that found by standard clinical analysis by light microscopy [75]. Kidney stones often form from crystals of calcium oxalates in urine. Inhibitors can prevent nucleation and influence the solid phase and intercrystallite interactions [76, 77]. Citrate, for example, is an important physiological inhibitor to the formation of calcium renal stones. Electrokinetic studies (see Section V-6) have shown the effect of various inhibitors on the surface potential and colloidal stability of micrometer-sized dispersions of calcium oxalate crystals formed in synthetic urine [78, 79]. 

Analysis. Excellent reviews of phosphate analysis are available (28). SoHds characterization methods such as x-ray powder diffraction (xrd) and thermal gravimetric analysis (tga) are used for the identification of individual crystalline phosphates, either alone or in mixtures. These techniques, along with elemental analysis and phosphate species deterrnination, are used to identify unknown phosphates and their mixtures. Particle size analysis, surface area, microscopy, and other standard soHds characterizations are useful in relating soHds properties to performance. SoHd-state nmr is used with increasing frequency. 

QCMB RAM SBR SEI SEM SERS SFL SHE SLI SNIFTIRS quartz crystal microbalance rechargeable alkaline manganese dioxide-zinc styrene-butadiene rubber solid electrolyte interphase scanning electron microscopy surface enhanced Raman spectroscopy sulfolane-based electrolyte standard hydrogen electrode starter-light-ignition subtractively normalized interfacial Fourier transform infrared... 

Atomic force microscopy (AFM) has become a standard technique for high-resolution imaging of the topography of surfaces. It enables one to see nanoscopic... 

Since our backbone 2 aPNA incorporates six Lys residues in its peptide sequence and is cationic at a physiological pH, we were optimistic that this aPNA would be taken up into cells without the need for any external carrier system. To answer the simple question of whether b2 aPNAs are intemahzed, a standard fluorescence microscopy experiment was performed to see if whole cells that were incubated with a fluorescent-labeled aPNA would internahze labeled material [70]. Chinese Hamster Ovary (CHO) cells in culture were incubated with BODIPY-la-beled TCCCT(b2) at 37 °C for various periods of time. Following incubation, the cells were rinsed in phosphate-buffered sahne (PBS), fixed with 4% formaldehyde at ambient temperature for 20 min, then washed with PBS and stored in a refrigerator until examined by fluorescence microscopy. 

Fig. 6. Electron microscopy of Ca -ATPase crystals in thin sections. Sarcoplasmic reticulum (2mg of protein/ml) was solubilized in the standard crystallization medium with C12E8 (2mg/mg protein) and incubated under nitrogen at 2°C for 15 days. The crystalline sediment was embedded in Epon-Araldite mixture and processed for electron microscopy. Depending on conditions during fixation, embedding, sectioning and viewing, the observed periodicities in different specimens varied between 103 and 147 A. Magnification, x 207000. From Taylor et al. [156].

The 1000 A column did not show any resolution between 312 nm and 57 nm particle sizes. Shown in Fig.2 are the calibration curves for the 2000 A and 3000 A columns and for their combination. The 57 nm particle standard appears to have been erroneously characterized by the supplier. This was subsequently confirmed by electron microscopy. The 2000 X column exhibited a sharp upturn in its calibration curve close to the exclusion limit. It is to be noted that while data points corresponding to 312 and 275 nm diameter particles appear on individual column calibration curves, they are not indicated for the calibration curve of the combination. This is because these larger diameter particles were completely retained in the packed colimms, generating no detector response. The percentage recovery for these particles from individual columns was considerably less than 100 resulting in their complete retention when the columns were combined in series. 

P. T. Callaghan 1994, Principles of Nuclear Magnetic Resonance Microscopy, Clarendon Press, Oxford, 490 pp. Standard reference textbook for imaging, some examples but with a focus on theory. 

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