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Exploration of the biological effects of transition metal ions in acupuncture points is essential to clarify the functional mechanism of acupuncture treatment. Here we show that in the SP6 acupuncture point (Sanyinjiao) the Fe ions are in a high-spin state of approximately t2g4.5eg1.5 in an Fe-N(O) octahedral crystal field. The Fe K-edge synchrotron radiation X-ray absorption fine structure results reveal that the Fe-N and Fe-O bond lengths in the SP6 acupuncture point are 2.05 and 2.13 A, respectively, and are 0.05-0.10 A longer than those in the surrounding tissue. The distorted atomic structure reduces the octahedral symmetry and weakens the crystal field around the Fe ions by approximately 0.3 eV, leading to the high-spin configuration of the Fe ions, which is favorable for strengthening the magnetotransport and oxygen transportation properties in the acupuncture point by the enhanced spin coherence. This finding might provide some insight into the microscopic effect of the atomic and electronic interactions of transition metal ions in the acupuncture point. Graphical Abstract ᅟ.

X-ray microscopy based on synchrotron radiation has become a fundamental tool in biology and life sciences to visualize the morphology of a specimen. These studies have particular requirements in terms of radiation damage and the image exposure time, which directly determines the total acquisition speed. To monitor and improve these key parameters, we present a novel X-ray microscopy method using a high-resolution zone plate as the objective and the matching condenser. Numerical simulations based on the scalar wave field theory validate the feasibility of the method and also indicate the performance of X-ray microscopy is optimized most with sub-10-nm-resolution zone plates. The proposed method is compatible with conventional X-ray microscopy techniques, such as computed tomography, and will find wide applications in time-resolved and/or dose-sensitive studies such as living cell imaging.

In this contribution we discuss the possibility of designing a modified transmission X-ray microscope by using fractal zone plates (Fzps) as diffractive optical elements. In the modified transmission X-ray microscope optical layout, we first introduced a fractal zone plate as the microscope objective. Indeed, a fractal zone plate cannot only be used as an image-forming component but also as a condenser element to achieve an extended depth of field. Numerical analysis reveals that fractal zone plates and conventional Fresnel zone plates have similar imaging capabilities under different coherent illumination. Using a fractal zone plate as a condenser we also simulated axial irradiance. Results confirm that fractal zone plates can improve focusing capability with an extended depth of field. Although preliminary, these simulations clearly reveal that fractal zone plates, when available, will be of great help in microscope layouts, in particular for foreseen high-resolution applications in the "water window" as strongly required in biological research.

The structures of selenium nanoparticles and nanotubes synthesized by the dismutation of precursor Na2SeSO3 under acidic condition in micellar solution are studied by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray absorption fine structure spectroscopy (XAFS). Spherical-like nanoparticles contain both amorphous and crystalline parts while, as shown by XRD patterns, nanotubes have the crystal structure of trigonal selenium (t-Se). They display quite different XANES spectral features indicating different local atomic arrangements. Theoretical XANES calculations show that the local structure around Se atom in the nanotubes is similar to a hexangular cylinder. Quantitative extended XAFS (EXAFS) analysis further shows that the average Se–Se bond length for both nanotubes and nanoparticles is 2.35 A.

The Morlet wavelet transformation (MT) was used to analyze Mn K-edge extended X-ray absorption fine structure (EXAFS) spectra of Mn-doped Si-based diluted magnetic semiconductor (DMS) thin films grown by the magnetron co-sputtering method. MT of EXAFS data shows that the Mn–Mn scattering path can be distinguished by the Mn–Si scattering path in the spectra of Mn x Si1−x DMS thin films. In all DMS thin films Mn atoms fill Si sites without forming Mn–Si compounds while Mn–Si compounds are present in the annealed analogues. From the analysis of experimental data we point out that low-concentration Mn-doped samples are characterized by a more symmetric structure.

There remains a pressing challenge in the efficient utilization of visible light in the photoelectrochemical applications of water splitting. Here, we design and fabricate pseudobrookite Fe2TiO5 ultrathin layers grown on vertically aligned TiO2 nanotube arrays that can enhance the conduction and utilization of photogenerated charge carriers. Our photoanodes are characterized by low onset potentials of ~0.2 V, high photon-to-current efficiencies of 40–50% under 400–600 nm irradiation and total energy conversion efficiencies of ~2.7%. The high performance of Fe2TiO5 nanotube arrays can be attributed to the anisotropic charge carrier transportation and elongated charge carrier diffusion length (compared with those of conventional TiO2 or Fe2O3 photoanodes) based on electrochemical impedance analysis and first-principles calculations. The Fe2TiO5 nanotube arrays may open up more opportunities in the design of efficient and low-cost photoanodes working in visible light for photoelectrochemical applications. Metal oxides are desirable photoanode materials due to their low cost and chemical stability, but they only work in the ultraviolet range. Here, Liu et al. design anode architecture that can absorb the visible light, while maintaining photon-to-current efficiency of 40% at an onset potential of 0.2 V.