In situ specimens

Specimens for testing shall be fabricated as described in ASTM D-4320, or carefully trimmed from field samples. (Sampling procedures for in situ specimens have a major influence on test results. Specimens trimmed from large chunk samples are desirable.)... 

Environmental-cell in situ specimen holders provide the possibility of investigating a nanoparticle s dynamic behaviour in real time, within a liquid or gaseous environment. These holders employ Micro-Electro-Mechanical Systems (MEMS) chips containing thin impermeable silicon nitride windows to isolate the liquid or gas from the microscope while remaining electron transparent. STEM is widely employed in environmental-cell studies as it allows good contrast when imaging through thick liquid layers.For example, it has been shown to be... 

Drained strength parameters of cohesionless soils are generally measured in either relatively simple direct shear (DS) tests or in more sophisticated consolidated-drained (CD) triaxial tests. In general, few laboratory strength tests are performed on in situ specimens of cohesionless soil due to the relative difficulty in obtaining undisturbed specimens. 

In the period 2002-2003 we focused on performing phase analyses of corrosion-induced damage to feed water pipelines in SGI6 near the heterogeneous weld. Visual inspections were done, and original in situ specimens were scraped off. The conclusions from the visual inspections (performed on 19 and 29 April 2002 at SG16) were as follows. 

When using a multitechnique approach to problem solving, care must be taken that the application of one technique to a specimen does not Jeopardize the validity of subsequent analyses by other techniques. Under this criterion if that validity is unaffected, then the technique first applied can be said to be nondestructive. The criterion puts obvious constraints on the sequence in which techniques should be used, beginning with the least destructive and ending with the most. A corollary of this criterion is that in cases where there are continuing ex situ or in situ specimen treatments requiring periodic analysis, then the analytical procedure should not itself affect the course of the treatment(s). 

A particular issue with the use of in situ measurements on land is that the area of interest is much larger than the size of the specimen that is analysed by individual measurements. Because a gamma detector counts radiation quanta that have arrived at the detector from any source, the size and shape of an individual specimen can never be fully known. This is in contrast to a laboratory measurement, where a specimen is removed from the target area and its mass and volume can be accurately determined. An assumption such as an area of 10 m diameter is clearly simplistic, because in reality the specimen size depends on several factors, e.g. the distributions of radionuclides and attenuation properties of the soil, also the intrinsic efficiency of the detector and the coimting time used. It would therefore be useful to be able to define more accurately the dimensions of an in situ specimen. This could assist at both the design and interpretation stages of an in situ gamma smvey. 

Propose a new method for estimating the size and shape of in situ specimens that can be used to optimise the design of objective-driven in situ surveys. 

IN SITU SPECIMEN SIZE AND APPLICATION TO SURVEY DESIGN 3.1 Estimating the Dimensions of an in situ Measurement. 

As reported before [Ref. 1], there are some essential parameters that influence the results of the testing, such as the thickness of the expired specimen, the quality and coarse grain of the built-in concrete, and the properties of the specimen-surface for the transducer s coupling. At the onset of testings none of tlrese parameters were available. As a result, we had to carry out preliminary investigations in order to prove the applicability of our testing-technique "in situ". 

In principle, there is no upper bound in measurements of particle velocity (or stress) using laser velocity interferometry. In practice, very high-pressure shock fronts can cause copious jetting of microparticles from the free surface (Asay et al., 1976), obscuring the surface from the laser beam. To alleviate this, optically transparent materials can be bonded to the specimen, and particle velocity measurements are then made at the specimen/window interface. This has the added advantage of simulating in situ particle velocity... 

The liner was compacted with two lifts, each 6-in. thick. A 1-ft3 block of soil was carved from the liner, and cylindrical test specimens were trimmed from upper and lower lifts and measured for hydraulic conductivity. A 3-in. diameter specimen also was cut, and hydraulic conductivity parallel to the lift interface was measured. The actual in situ hydraulic conductivity, a high 1 x 10-4 cm/s, was verified both by the infiltration measurements and the underdrain measurements. 

Bouin s solution is one of the traditional ways to harden cell pellet. Some cytologists believe it provides the best cellular details, especially nuclear features in cell blocks.28 The major steps are (1) After centrifugation, fix the cell pellet with Bouin s solution. (2) After 2h, discard the solution. (3) Remove the hardened cell pellet from the tube, wrap it with lens paper, and transfer it into a cassette for further processing. We have been using this method for many years. In our experience, most of the time, ICC results are consistent with IHC from the surgical specimen. The biggest drawback of this method is the toxicity of Bouin s fixative which creates biohazard and safety issues for the laboratory. We also found cell blocks gave poor fluorescence in situ hybridization (FISH) results after Bouin s fixation. 

Additionally, an in situ experiment was performed to evaluate HBCD bioaccumulation. In site C5, clean barbels were exposed to the environment. As a control, the same experiment was performed in site C2. Twenty specimens of barbel were caged into each one of two stainless steel devices that were placed on the river-bed at the two locations. Nine specimens were immediately frozen to be analyzed as blanks. After 15 days of exposure, no mortality was observed in the cages. Table 4 shows levels of HBCD accumulated in the caged barbels exposed in sites C2 and C5. Accumulation at site C2 was negligible, as values measured after the exposure were even lower than those of the fishes not exposed. However, at site C5, after the... 

Imaging mass spectrometry involves MS performed on tissue sections mounted on a MALDI plate. The mass spectra generate images and an in situ protein expression profile of the specimen is analyzed. Specifically, the frozen tissue sections applied to a MALDI plate are subjected to laser interrogation and analyzed at regular spatial intervals. The mass spectral data obtained at different intervals are compared to generate a spatial distribution of masses (proteins) across the tissue section. 

Mass spectrometers have been used at some level in all of these types of investigations because of their unsurpassed sensitivity and specificity, their multicomponent analytical capability and, in some cases, their ability to provide precise and accurate isotope ratios. Traditional methods of analysis typically involve the collection of water and sediment samples, or biological specimens, during field expeditions and cmises on research vessels (R/Vs), and subsequent delivery of samples to a shore-based laboratory for mass spectrometric analyses. The recent development of field-portable mass spectrometers, however, has greatly facilitated prompt shipboard analyses. Further adaptation of portable mass spectrometer technology has also led to construction of submersible instruments that can be deployed at depth for in situ measurements. 

One of the first in situ Mossbauer investigations of the behavior of iron oxides in electrochemical enviroments was the result of a fortuitous incident in which a specimen containing iron phthalo-... 

The quadrupole splitting of the heat treated FePc/XC-72 electrode measured ex situ, prior to the electrochemical experiments, was larger than that found in situ. Smaller values for A have been reported for certain ferric hydroxide gels and for small particles of FeOOH (Table II), and thus the effect associated with the immersion of the specimen in the electrolyte is most probably related to the incorporation of water into the oxide structure. For this reason, the material observed in situ at this potential will be referred to hereafter as FeOOH(hydrated), without implying any specific stoichiometry. 

Like almost any other technique, thermoelectric power, does however also have some of its own limitations. For example, thermoelectric power is a contact method, which means that if hydrogen content needed to be measured on the exterior of a coated pipeline, the coating would need to removed, however in-line pig inspection would allow for in-situ inspection of the pipeline inner wall. In these limited cases, alternative complimentary techniques can be utilized. Low frequency impedance measurements can provide an alternative non-destructive, non-contact method of measuring hydrogen through an entire specimen thickness, dependent upon lift-off. 

At the same time, one should notice that the real catalysts are applied in the gas/liquid environments at usually an increased temperature so that dynamic structural evolution of a real catalyst would not be probed in a conventional electron microscope. To bridge the gap, in situ environmental electron microscope is developed by placing a micoreactor inside the column of an electron microscope to follow catalytic reaction processes [58-62], However, the specimen in an in situ TEM may suffer from interaction with ionised gas (plasma), making the interpretation of in situ TEM study of catalytic reaction more complicated. Characterisation of static, post-reaction catalysts is still the most commonly used. Well-designed model catalysts and reasonable interpretation of the results are essential to a successful study. 

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