X-ray microimaging

Kemner KM, Yun W, Cai Z, Lai B, Lee H-R, Maser J, Legnini DG, Rodriques W, Jastrow JD, Miller RM, Pratt ST, Schneegurt MA, Kulpa CF Jr (1999) Using zone plates for X-ray microimaging and microspectroscopy in environmental samples. J Synchrotron Rad 6 639-641 Kendelewicz T, Doyle CS, Carrier X, Brown GE Jr (1999) Reaction of water with clean surfaces of MnO(lOO). Surf Rev Lett 6 1255-1263... 

The use of X-ray tomography is relatively new in the membrane field. The first experimental use of SRpCT was reported by Remigy et al. [5, 6], although Frank et al. used X-ray tomography in 2000 to observe a hemodialysis module [7]. They presented 3D reconstructed structures of UF and MF hollow fiber membranes. Yeo et al. published a paper in 2005 using X-ray microimaging (XMI) to observe the deposition of ferric hydroxide inside the fiber lumen [8] and later Chang et al. observed the flow characteristics in a hollow fiber lumen [9]. 

To circumvent these difficulties and to obtain shorter acquisition times, it is possible to take only one simple radiograph. Yeo et al. [8] applied this principle in 2006 by using a technique called X-ray microimaging (XMI). They observed the deposition of particles of iron hydroxide (sizes from 0.1 pm to 10 pm) during a dead-end filtration into the lumen of a PAN fiber (nominal size pore 0.5 pm, outer diameter 0.8 mm). The images they obtained, using a pixel size equal to 1pm, were the projections of the fiber structure (i.e. membrane plus pores filled with water) and the deposition of iron hydroxide. The acquisition time was short (1-10 s) and images were recorded every 3 min. 

Snigerev, A., Snigireva, I., Kohn, V., Kuznetsov, S., and Schelokov, I. 1995. On the possibilities of X-ray phase-contrast microimaging by coherent high-energy synchrotron radiation. Rev. Sci. Instrum. 66, 5486-5492. 

There are three indirect, nondestructive measurement techniques to determine thermal resistance acoustic microimaging, x-ray, and thermal test chips. The acoustic microimaging and x-ray methods can be used in both development and production, but the thermal test chip is restricted to development. The first two indirect thermal techniques find the amount of voiding in the thermal path and, through the use of thermal modeling, calculate the thermal resistance. The thermal test chip can only find the thermal resistance capability of the physical design. 

For the failure analysis of the test samples after the harsh environmental tests, various analysis tools are employed, e.g., scanning electron microscopy (SEM) with a cross-sectional analyzing technique, x-ray microscopy, A-, B-, and C-mode scanning acoustic microscopy (A-SAM, B-SAM, and C-SAM, respectively), and tomographic acoustic microimaging (TAMI), to analyze the failure samples. The continuous measurement of the electrical resistance should consequently be conducted during all of the environmental tests mentioned above. 

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