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Even-odd effect in higher-order holographic production of electron vortex beams with nontrivial radial structures
摘要： Structured electron beams carrying orbital angular momentum are currently of considerable interest, both from a fundamental point of view and for application in electron microscopy and spectroscopy. Until recently, most studies have focused on the azimuthal structure of electron vortex beams with well-defined orbital angular momentum. To unambiguously define real electron-beam states and realize them in the laboratory, the radial structure must also be specified. Here we use a specific set of orthonormal modes of electron (vortex) beams to describe both the radial and azimuthal structures of arbitrary electron wavefronts. The specific beam states are based on truncated Bessel beams localized within the lens aperture plane of an electron microscope. We show that their Fourier transform set of beams can be realized at the focal planes of the probe-forming lens using a binary computer-generated electron hologram. Using astigmatic transformation optics, we demonstrate that the azimuthal indices of the diffracted beams scale with the order of the diffraction through phase amplification. However, their radial indices remain the same as those of the encoding beams for all the odd diffraction orders or are reduced to the zeroth order for the even-order diffracted beams. This simple even-odd rule can also be explained in terms of the phase amplification of the radial profiles. We envisage that the orthonormal cylindrical basis set of states could lead to new possibilities in phase contrast electron microscopy and spectroscopy using structured electron beams.
关键词： truncated Bessel beams,astigmatic transformation,computer-generated hologram,electron vortex beams,orbital angular momentum,phase amplification
更新于2025-09-23 15:22:29
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A Sample-to-Targeted Gene Analysis Biochip for Nanofluidic Manipulation of Solid-Phase Circulating Tumor Nucleic Acid Amplification in Liquid Biopsies
摘要： The use of circulating tumor nucleic acids (ctNA) in patient liquid biopsies for targeted genetic analysis is rapidly increasing in clinical oncology. Still, the call for an integrated methodology that is both rapid and sensitive for analyzing trace ctNA amount in liquid biopsies, has unfortunately not been fully realized. Herein, we performed complex liquid biopsy sample-to-targeted genetic analysis on a biochip with 50 copies-detection limit within 30 min. Our biochip uniquely integrated: 1) electrical lysis and release of cellular targets with minimal processing; 2) nanofluidic manipulation to accelerate molecular kinetics of solid-phase isothermal amplification; 3) single-step capture and amplification of multiple NA targets prior to nanozyme-mediated electrochemical detection. Using prostate cancer liquid biopsies, we successfully demonstrated multifunctionality for cancer risk prediction; correlation of serum and urine analyses; and cancer relapse monitoring.
关键词： solid-phase amplification,microfluidics,risk stratification,liquid biopsy,prostate cancer
更新于2025-09-10 09:29:36