[en] Highlights: • A compact transfer lens doublet using permanent magnet. • A Cs corrector combine tunable condenser lens and the newly designed transfer lens doublet. • A compact hexapole/ doublet transfer lens Cs corrector for desktop EM. - Abstract: The desktop Electron Microscopes (desktop EMs) have been commercialized in the recent years, offering a spatial resolution around 1 nm in scanning-transmission mode in a routine operation. For the purpose of further improvement in spatial resolution and signal / noise, one may need an aberration corrector with a compact form in order to fit into a desktop EM. In this paper, the permanent magnets with tunable coil are implemented as a transfer lens doublet to realize a compact hexapole corrector for a desktop EM. It will be shown that, with a proper design of permanent magnet transfer lens doublet and hexapole lens, we can generate a negative Cs and avoid the second-order axial astigmatism to reduce the final spot size at the sample plane to be better than 0.5 nm for a field emission source. To fulfill with the required condition of a hexapole corrector, a tunable lens is implemented to adjust the magnetic field for compensating the practical error from the permanent magnet.

[en] A tabletop scanning electron microscope (SEM) utilizes permanent magnets as condenser lenses to minimize its size, but this sacrifices the tunability of condenser lenses such that a tabletop system can only be operated with a fixed accelerating voltage. In contrast, the traditional condenser lens utilizes an electromagnetic coil to adjust the optical properties, but the size of the electromagnetic lens is inevitably larger. Here, we propose a tunable condenser lens for a tabletop SEM that uses a combination of permanent magnets and electromagnetic coils. The overall dimensions of the newly designed lens are the same as the original permanent magnet lens, but the new lens allows the tabletop SEM to be operated at different accelerating voltages between 1 kV and 15 kV. - Highlights: • A compact condenser lens combines both permanent magnet and coils. • A tunable lens is designed to keep the same focal point for voltage 1 to 15 kV. • A miniature tunable lens which can directly fit into tabletop SEM.

[en] Beijing has a large number of nuclear technology utilization units and involves a wide range of industries. The application of nuclear technology has brought great benefits to mankind, and at the same time, the amount of radioactive waste produced in the city is also increasing day by day. The 'safety' of radioactive waste is not only one of the key factors affecting the sustainable development of the nuclear technology application, but also related to the social stability, public health and environmental safety of the capital. According to the existing laws and regulations, based on the actual situation of Beijing and combined with the practice of Radioactive Waste Management, some suggestions are put forward to improve the safety management of radioactive waste in Beijing. (authors)

[en] In a modified Twyman-Green interferometer, the optical path variation is measured with the heterodyne central fringe identification technique, as the light beam is focused by a displaced microscopic objective on the front/rear surface of the test transparent plate. The optical path length variation is then measured similarly after the test plate is removed. The geometrical thickness of the test plate can be calculated under the consideration of dispersion effect. This method has a wide measurable range and a high accuracy in the measurable range.

[en] Based on the density functional theory method, the ab initio calculation with GGA+U was performed to investigate the electronic structure and properties of W-doped TiO₂. The results indicated that W-doping induced ferromagnetism and shifted the absorption spectra to visible light region. The ferromagnetism derived from the spin-split of O 2p and W 5d caused by p–d orbit hybridization. Several impurity bands under the conduction band decreased the band gap. The experiment results illustrated that the ferromagnetism had occurred and the absorption spectra had a shift to visible light region in W-doped TiO₂ samples. The experiment results are consistent with the calculation ones

[en] The idea of signal processing with cross correlation technique is not a new technology. A lot of research have been done in this field since 1930s and only been implemented in 1960s. This technique is used mainly in calculating the velocity of the flow of small particles in pipe and it has been proven effective in solving problems that was unable to be solved. In this study, the big scale (Automatic Vacuum Loader) and small scale (the rotating ball) test apparatus are used to find the velocity of the flow of particles. The flow is detected by two axially spaced electrodynamics sensors, with known length spacing. Two methods are used to measure the velocity of the flow or particles. The first method is the software (X-correlator) that has been developed earlier to interact with the interface board AX5412 for obtaining the data from both of the test apparatus. The second method uses the HP dynamic signal analyzer for capturing the data from the test apparatus and obtaining the cross correlation function of the data. With the time shift obtained from the peak of the cross correlation coefficient, the velocity of the particles can be calculated. In addition data comparisons from all the analysis are presented (author)

[en] Highlights: • Synthesis of highly phosphonic acid functionalized benzene-bridged PMOs. • Phosphonic acid loaded PMOs as adsorbent for cationic and anionic dyes. • Due to electrostatic interaction the adsorbent has high dye adsorption capacity. • π–π stacking interaction between benzene and dye enhances adsorption capacity. • Intraparticle diffusion played a dominant role in the adsorption process. - Abstract: Periodic mesoporous organosilicas (PMOs) with benzene bridging groups in the silica wall were functionalized with a tunable content of phosphonic acid groups. These bifunctional materials were synthesized by co-condensation of two different organosilane precursors, that is, 1,4-bis(triethoxysilyl)benzene (BTEB) and sodium 3-(trihydroxysilyl)propyl methyl phosphate (SPMP), under acidic conditions using nonionic surfactant Brij-S10 as template. The materials exhibited well-ordered mesostructures and were characterized by X-ray diffraction, nitrogen sorption, TEM, TGA, FTIR, and solid-state NMR measurements. The materials thus obtained were employed as adsorbents to remove different types of dyes, for example, cationic dyes methylene blue and phenosafranine, anionic orange II, and amphoteric rhodamine B, from aqueous solutions. The materials exhibited a remarkably high adsorption capacity than activated carbon due to their ordered mesostructures, a large number of phosphonic acid groups, and high surface areas. The adsorption was mainly governed by electrostatic interaction, but also involved π–π stacking interaction as well as hydrogen bonding. The adsorption kinetics can be better fitted by the pseudo-second order model. The adsorption process was controlled by the mechanisms of external mass transfer and intraparticle diffusion. The materials retained more than 97% dye removal efficiency after use for five consecutive cycles

[en] Highlights: • A novel overoxidized poly(3,4-ethylenedioxythiophene) film is obtained. • The film structure favors the adsorption of dopamine. • The sensor is able to detect dopamine in the presence of ascorbic acid (1000X). - Abstract: An overoxidized poly(3,4-ethylenedioxythiophene) film-modified screen-printed carbon electrodes (SPCE/PEDOT_o_x) was prepared and characterized by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle techniques. The obtained film is a porous structure with highly abundant oxygen functionality. The SPCE/PEDOT_o_x could adsorb cations strongly and perform catalytic oxidation of biomolecules. The potential-induced adsorption of dopamine was observed for SPCE/PEDOT_o_x. A simple medium-exchange procedure was developed for the selective determination of dopamine by the use of the dopamine-adsorbed electrode. Under optimal differential pulse voltammetry (DPV), the proposed assay can be employed in the determination of submicromolar concentration of dopamine without the coexisting interferences of ascorbic acid (1000-fold) and uric acid (10-fold)

[en] In the China ADS (CIADS) proton accelerator, multipacting is an issue of concern for the superconducting cavities. The parallel codes Omega3P and Track3P, developed at SLAC under the support of the DOE SciDAC program, have been used to calculate the electromagnetic field distribution and to analyze the multipacting barriers of such cavities. In this paper, two types of 162.5 MHz half wave resonator cavities, HWR-010 (cylinder type with β of 0.10) and HWR-015 (taper type with β of 0.15) have been analyzed, and the results of the multipacting analyses show that the resonant electrons occur at different regions with different accelerating gradients. The two-point 1st order multipacting on the short plate has also been researched and discussed. (authors)

[en] The decay heat of radioactive isotopes is one of main concerns in designing a reactor core as well as designing a spent fuel repository. In particular, the effective removal of the decay heat during accidents such as high or low pressure conduction cooling events is a crucial factor which determines the main design parameters of a very high temperature gas cooled reactor (VHTR) core. In a previous work, the applicability of the ORIGEN2 code for the analysis of VHTR core decay heat was demonstrated. The one-group cross sections of major actinides in the ORIGEN2 code were replaced with those generated from the HELIOS model for a PMR200 fuel block in the work. In this study, the decay heat of the PMR200 VHTR core was analyzed by using McCARD and ORIGEN2 codes and the accuracy of the decay heat calculation by the HELIOS/ORIGEN2 codes was verified by comparing it with those from McCARD/ORIGEN2 calculation