A fast, convenient way to determine the age of bones and ivories is important both in forensics and for classifying art objects in collections of art experts, restorers, art galleries and museums. Knowing the age of elephant tusks is also essential because there are many date-specific regulations of ivory trade. Radiocarbon dating is the standard method used to determine the age of organic materials, but it is expensive, time consuming, and damages the sample in the process. Raman spectroscopy is sensitive to rotational and vibrational molecular transitions, and also intermolecular vibrations. Therefore, it can provide information about sample make up, such as proteins and minerals, as well as detect spectral signatures associated with structural changes in molecules. Since Raman spectroscopy identifies the molecular bonds present in a sample, it is often used to determine its chemical composition. Bones and ivories contain two primary components: collagen and bioapatite. As the protein collagen deteriorates with time, its Raman signal decreases. The ratio of collagen-to-bioapatite peaks, therefore, is smaller in the older samples compared to the younger ones, providing a basis for sample dating. We employed Raman spectroscopy to non-destructively determine the age of several elephant tusk fragments. We have also used it to identify ivory imitations made of vegetable and plastic materials. Such materials have entirely different chemical composition, and their spectra are easily distinguished from those of bone and ivory. Peak fitting was employed to determine collagen and bioapatite components.
Sustained delivery of growth factors, proteins, drugs and other biologically active molecules is necessary for tissue engineering applications. Electrospun fibers are attractive tissue engineering scaffolds as they partially mimic the topography of the extracellular matrix (ECM). However, they do not provide continuous nourishment to the tissue. In search of a biomimetic scaffold for salivary gland tissue regeneration, we previously developed a blend nanofiber scaffold composed of the protein elastin and the synthetic polymer polylactic-co-glycolic acid (PLGA). The nanofiber scaffold promoted in vivo-like salivary epithelial cell tissue organization and apicobasal polarization. However, in order to enhance the salivary cell proliferation and biomimetic character of the scaffold, sustained growth factor delivery is needed. The composite nanofiber scaffold was optimized to act as a growth factor delivery system using epidermal growth factor (EGF) as a model protein. The nanofiber/EGF hybrid nanofibers were synthesized by double emulsion electrospinning where EGF is emulsified within a water/oil/water (w/o/w) double emulsion system. Successful incorporation of EGF was confirmed using Raman spectroscopy. EGF release profile was characterized using enzyme-linked immunosorbent assay (ELIZA) of the EGF content. Double emulsion electrospinning resulted in slower release of EGF. We demonstrated the potential of the proposed double emulsion electrospun nanofiber scaffold for the delivery of growth factors and/or drugs for tissue engineering and pharmaceutical applications.
A system using a wide-slot beam and simple antiscatter grids or slots has been designed to provide a localized map of tissue type that could be overlaid on the simultaneous conventional transmission image to provide an inexpensive, low dose adjunct to conventional screening mammography. Depth information is obtainable from the stereoscopic viewing angles. The system was demonstrated to produce observable contrast between adipose tissue and a phantom chosen to mimic carcinoma at an exposure comparable with screening mammography. Imaging data was collected over a range of system parameters to optimize contrast and to allow verification of simulation modeling.
X-ray coherent scatter is dependent upon the molecular structure of the scattering material and hence allows differentiation between tissue types with potentially much higher contrast than conventional absorption-based radiography. Coherent-scatter computed tomography has been used to produce images based on the x-ray scattering properties of the tissue. However, the geometry for CT imaging requires a thin fan beam and multiple projections and is incommensurate with screening mammography. In this work we demonstrate progress in a developing a system using a wide slot beam and simple anti-scatter grid which is adequate to differentiate between scatter peaks to remove the fat background from the coherent scatter image. Adequate intensity in the coherent scatter image can be achieved at the dose commonly used for screening mammography to detect carcinoma surrogates as small as 2 mm in diameter. This technique would provide an inexpensive, low dose, simultaneous adjunct to conventional screening mammography to provide a localized map of tissue type that could be overlaid on the conventional transmission mammogram. Comparisons between phantom measurements and Monte Carlo simulations show good agreement, which allowed for detailed examination of the visibility of carcinoma under realistic conditions.
Conventional mammography has poor contrast between healthy tissue and carcinoma due to small differences in
attenuation. Since interference of coherently scattered radiation depends on the intermolecular spacing, it can provide
new information with higher contrast. A Monte Carlo simulation was developed for coherent scatter imaging. The
modeled design exploits a conventional scan slot mammography system with an additional anti-scatter grid tilted at the
characteristic angle of carcinoma. Preliminary results are promising and agree with experimental measurements on
phantom systems. The effect of changing grid tilt angle and sample detector distance were studied in order to begin
system optimization.
The system using a wide slot beam and simple anti-scatter grid has been designed to provide a localized map of tissue
type that could be overlaid on the simultaneous conventional transmission image to provide an inexpensive, low dose
adjunct to conventional screening mammography.
The purpose of this work is to explore whether a screening mammography system can be designed to exploit coherent
scatter to provide some tissue type information.
A system using a wide slot beam and simple anti-scatter grid has been designed to
provide a localized map of tissue type that could be overlaid on the simultaneous
conventional transmission image to provide an inexpensive, low dose adjunct to
conventional screening mammography. The system was demonstrated to differentiate
between scatter peak angles corresponding to adipose tissue and carcinoma. Adequate
intensity in the coherent scatter image can be
achieved at a dose commonly used for screening
mammography. Depth information is obtainable
from the stereoscopic viewing angles. Phantom
imaging measurements and Monte Carlo
simulations show good agreement.
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