Qiaofeng Xu

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Differential X-ray phase-contrast tomography (DPCT) refers to a class of promising methods for reconstructing the X-ray refractive index distribution of materials that present weak X-ray absorption contrast. The tomographic projection data in DPCT, from which an estimate of the refractive index distribution is reconstructed, correspond to one-dimensional(More)
The development of spectral computed tomography (CT) using binned photon-counting detectors has garnered great interest in recent years and has enabled selective imaging of K-edge materials. A practical challenge in CT image reconstruction of K-edge materials is the mitigation of image artifacts that arise from reduced-view and/or noisy decomposed sinogram(More)
The in vitro investigation of many optically opaque biological microstructures requires 3D analysis at high resolution over a large field of view. We demonstrate a new nondestructive volumetric imaging technique that eliminates the structural and computational limitations of conventional 2D optical microscopy by combining x-ray phase-contrast tomography(More)
A method for constructing conformational models of flexible complex polysaccharides on the basis of NMR data and molecular modeling is described and is applied to a polysaccharide which is a lectin-binding receptor important in coaggregation of oral bacteria. The method involves uniform biosynthetic enrichment of the polysaccharide with 13C which allows(More)
The development of spectral X-ray computed tomography (CT) using binned photon-counting detectors has received great attention in recent years and has enabled selective imaging of contrast agents loaded with K-edge materials. A practical issue in implementing this technique is the mitigation of the high-noise levels often present in material-decomposed(More)
Vibrio vulnificus is a pathogenic gram-negative bacterium, endemic to brackish waters, which is often isolated from sediments, from the water column or from shellfish. It is associated with wound infections and septicemia in humans and the virulence of V. vulnificus has been strongly associated with encapsulation. The capsular polysaccharide purified from a(More)
Vibrio cholerae O139 Bengal has recently been identified as a cause of epidemic cholera in Asia. In contrast to V. cholerae O1, V. cholerae O139 Bengal has a polysaccharide capsule. As determined by high-performance anion-exchange chromatography and 1H nuclear magnetic resonance analysis, the capsular polysaccharide of V. cholerae O139 Bengal strain Al1837(More)
As the performance of photovoltaic cells approaches the Shockley-Queisser limit, appropriate schemes are needed to minimize the losses without compromising the current performance. In this paper we propose a planar absorber-mirror light trapping structure where a conventional mirror is replaced by a meta-mirror with asymmetric light scattering properties.(More)
PURPOSE The development of iterative image reconstruction algorithms for cone-beam computed tomography (CBCT) remains an active and important research area. Even with hardware acceleration, the overwhelming majority of the available 3D iterative algorithms that implement nonsmooth regularizers remain computationally burdensome and have not been translated(More)
Finding the wavevectors (eigenvalues) and wavefronts (eigen-vectors) in nanostructured metasurfaces is cast as a problem of finding the complex roots of a non-linear equation. A new algorithm is introduced for solving this problem; example eigenvalues are obtained and compared against the results from a popular, yet much more computationally expensive(More)