Robust Energy Calibration Technique for Photon Counting Spectral Detectors.

This paper describes the implementation of a novel and robust threshold energy calibration method for photon counting detectors using polychromatic X-ray tubes. Methods often used for such energy calibration may require re-orientation of the detector or introduce calibration errors that are flux and acquisition time-dependent. Our newly proposed "differential intensity ratios" (DIR) method offers a practical and robust alternative to existing methods. We demonstrate this robustness against photon flux used in calibration, spectral errors such as pulse pile-up as well as the detector's inherent spectral resolution limits. The demonstrated significant insensitivity of the proposed DIR signature to detector spectral distortions and energy resolution is a key finding. The proposed DIR calibration method is demonstrated using Medipix3RX detectors with a CdTe sensor under varying flux conditions. A per pixel calibration using the DIR method has also been implemented to demonstrate an improvement over the global energy resolution of the PCD.

DNA Origami Structures Interfaced to Inorganic Nanodevices.

We describe here one way to achieve hybrid DNA-inorganic nanostructures on rigid flat insulating substrates. We report methods to prepare rectangular DNA origami and incubate them onto arrays of anchoring gold nanodots either in a static solution or in a microfluidic system. We give details on the design and lithographic methods employed to pattern usable arrays of gold nanoanchors on naturally oxidized silicon wafer chips. Scanning electron and atomic force microscopy methodological details are also given for obtaining the relevant characterizations of the immobilized and ordered DNA origami.

Suspending DNA Origami Between Four Gold Nanodots.

Rectangular DNA origami functionalized with thiols in each of the four corners immobilizes by self-assembly between lithographically patterned gold nanodots on a silicon oxide surface.