Scanning Electron Microscopy acid treatment method

Hasle and Fryxell (1) developed the classical method of cleaning diatoms by acid treatment in the late 1960s. This technique is probably the most commonly used for both light and scanning electron microscopy analysis and can be found published in many current taxonomy and morphology papers such as Hasle (4) and Villac and Fryxell (5). Examples of cells prepared using the acid treatment method are pictured in Fig. 1. The method published by Hasle and Fryxell (1) involves the following steps, which should be carried out under a chemical fume hood ... 

In light of the fact that coal ash is measured by removal (combustion) of the organic part of the coal, there are methods for measuring the mineral matter content of coal. Such a method involves demineralization of the coal that depends on the loss of weight of a sample when it is treated with aqueous hydrofluoric acid at 55 to 60°C (130 to 140°F) (Radmacher and Mohrhauer, 1955 Given and Yarzab, 1978 ISO 602). However, pyrite is not dissolved by this treatment and must be determined separately. Other methods include the use of physical techniques such as scanning electron microscopy and x-ray diffraction (Russell and Rimmer, 1979). 

Reports of textiles recovered from marine sites are uncommon. Wool and flax fibers from the Mary Rose and the Wasa have been identified employing optical and scanning electron microscopy (/5). The fiber content of the sails of the Wasa were identified as "vegetable but the method for fiber identification was not described 14). Morris and Seifert (75) describe treatment of textiles from the Defence with oxalic acid but do not indicate how they identified the linen, hemp, and silk fibers that they report are present. Conservation treatment of a silk cocade from the Michault was described 16). 

Nanocrystalline yttria (Y2O3) powders with most suitable characteristics for the fabrication of yttria crucibles were synthesized by the sol-gel method [85]. The combustion synthesis method was used starting with high-purity (99.9%) yttrium nitrate hexahydrate and citric acid. Different fuel to oxidant (citric acid/nitrate) ratios (0.25, 0.5, 0.75, 1.0, and 1.1) were tested. These mixtures were heated at 373 K until a viscous gel was formed, and its decomposition into powder formation was realized by thermal treatment at 473 K for 3 h. In all mixtures, yttria powders were obtained by thermal treatment at 1073 K. Scanning electron microscopy (SEM) showed that these powders were porous, whereas high-resolution transmission electron microscopy (HRTEM) revealed that they consist of randomly oriented cuboidal nanocrystallites with an average crystallite size of about 17-30 nm. In order to obtain dense ceramics, the powders were compacted as pellets at 120 MPa and were sintered at 1673 K. Pellets with a sintered density as high as 98-99% of the theoretical density could be obtained from powders prepared with fuel to oxidant ratios (/ ) of 0.75 and 1.0. 

Substrate Characterization. Test coupons and panels of 7075-T6 aluminum, an alloy used extensively for aircraft structures, were degreased In a commercial alkaline cleaning solution and rinsed In distilled, deionized water. The samples were then subjected to either a standard Forest Products Laboratories (FPL) treatment ( 0 or to a sulfuric acid anodization (SAA) process (10% H2SO4, v/v 15V 20 min), two methods used for surface preparation of aircraft structural components. The metal surfaces were examined by scanning transmission electron microscopy (STEM) In the SEM mode and by X-ray photoelectron spectroscopy (XPS). 

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