[en] The serious charge recombination originates from the thermal instability of perovskite/ZnO and the low electron injection efficiency of ZnO. It is the important issue to be improved in ZnO-based perovskite solar cell (PSC). In this paper, the core-shell structure of ZnO@TiO₂ nanorod arrays (NRs) is designed as electron transport layer (ETL) for PSC. A novel synthesis of PSC based on ZnO@TiO₂ NRs in ambient atmosphere was proposed. The photoelectric conversion efficiency (PCE) of the core-shell device is 50.46% higher than that of common ZnO nanorod device. This is due to the improved interface contact between nanorods and perovskite layer, and the suppression of charge recombination. The PCE of the TiO₂ modified device shows still more than 83% after 168 h, compared to that of the pristine one which decreased to less than 50%. This is due to TiO₂ modification which can serve as a buffer layer to avoid direct contact between perovskite films and ZnO NRs, and inhibits the decomposition of perovskite film on ZnO NRs. Both theoretical calculation and Raman test result show that the interaction between CH₃NH₃PbI₃ and TiO₂ is mainly the bonding between I atoms of PbI₂ slabs and Ti atoms of the TiO₂ surface at PbI₂/TiO₂ interface. The mechanism of carrier transport and recombination in the PSC based on ZnO and ZnO@TiO₂ NRs was also discussed. These results highlight the potential of ZnO@TiO₂ NRs as ETL for all-solid-state PSC with high efficiency and good stability.

[en] The spread of network rumors has always been a research hotspot. How information flows in social networks is a question of interest to us. Based on the theory of fluid mechanics, the dissemination model is constructed, and the dissemination mechanism of network rumor is explored. Through numerical simulation, it is found that the flow of rumor information has a strong correlation with the subject of rumor dissemination and their relationship. The dissemination law of rumor information is revealed, which provides theoretical support for rumor control and governance. (paper)

[en] Highlights: • Perovskite film modified by PVP/PEG mixture was prepared by a two-step method in air. • The cell with 1.5 wt%PVP/0.5 wt%PEG shows 30% PCE increasement compared with pure one. • The cell with 1.5 wt% PVP/0.5 wt%PEG retains 76% of its initial PCE value for 30 days. • The interactions between CH₃NH₃PbI₃ and PVP/PEG improve film quality and stability. • The bondings between perovskite and PVP/PEG increase cell efficiency and stability. -- Abstract: The key to commercialization of organic‐inorganic lead halide perovskite solar cells (PSCs) is to achieve high photoelectric conversion efficiency (PCE) and long-term stability under ambient condition. In this paper, polymer mixture of polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) with appropriate mass ratio are incorporated into PbI₂ precursor solution in the preparation process of perovskite film via two-step sequential deposition method in air. The PCE of polymer mixture modified PSC based on ZnO@TiO₂ nanorod arrays is better than those of the PSC with single polymerPVP or PEGand the pristine one, and the PCE of 1.5 wt%PVP/0.5 wt%PEG modified device increased by 30% compared with that of the unmodified one, which is mainly a consequence of the better quality of perovskite film caused by the synergistic effect including the strong attraction between the C=O in PVP and Pb²⁺ in perovskite, and the intense hydrogen bond between O atoms from PEG and H atoms in CH₃NH₃⁺. Moreover, polymer mixture modified PSC also represents better air stability compared with the device with single polymer or the pristine onewhich is largely attributed to the exceptional hygroscopicity of PVP/PEG mixture, the synergistic stabilization of perovskite structure and inhibition of ion migration by the bondings between polymer mixture and perovskite. Furthermore, the mechanism of the interaction between PVP/PEG mixture and CH₃NH₃PbI₃ to increase the efficiency and stability of the PSC was also studied. Our work offers an effective additive to simultaneously improve the efficiency and stability of the PSCs in high humidity environment for further commercial application.

[en] A Compact Spectrometer for Heavy IoN Experiments (CSHINE) has been recently built for the studies of heavy ion reactions at intermediate energies. CSHINE consists of a Si-Si-CsI telescope array and a parallel plate avalanche counter (PPAC) array. Each telescope consists of a thin single-sided silicon strip detector and a thick double-sided silicon strip detector backed by a 3 × 3 CsI(Tl) crystal hodoscope. The thicknesses of the silicon detectors are optimized in order to identify various types of light charged particles in a wide energy range. PPAC is a large-area two-dimensional position-sensitive gas detector, which records fission fragments with the intrinsic efficiency of approximately 100% but filters out light charged particles at properly selected working conditions. In the phase-II run, four Si-Si-CsI telescopes and three PPACs have been installed and operated in the beam experiment with 25 MeV/u Kr+Pb reactions. Particle identification for isotopes from Hydrogen to Boron has been achieved with the Si-Si-CsI telescopes, while excellent timing and position resolution have been achieved with the PPACs.

[en] ZnO as electron transfer layer in perovskite solar cells (PSCs) has a lot of advantages including high electron mobility and low processing temperature. However, because of the reported instabilities of perovskite layers deposited on ZnO, the application of ZnO in perovskite solar cells has been restricted. In this paper, highly ordered ZnO nanorod arrays have been synthesized by a polymer soft template method, and then modified by ZnSe via a successive ion layer adsorption and reaction method (SILAR). Field emission scanning electron microscope, X-ray diffractometer, UV–vis spectrophotometer, fluorophotometer and photovoltaic measurements were used to study the effects of ZnSe modification on the morphology, structure, light absorption and charge transfer of perovskite films and the performance of the PSCs based on ZnO nanorod arrays. The photoelectric conversion efficiency (PCE) of the PSC with ZnSe modification significantly enhanced by 27%, as compared to that of the pristine one, which is attributed to the suitable band alignment, better carrier separation and higher charge transfer efficiency with ZnSe modification. Meanwhile, ZnSe modification can also improve the air stability of the PSCs. This study promotes the development of ZnO nanorod arrays based PSCs with some new approaches and provides a useful reference.

[en] A novel Fe₃O₄-MWCNTs@Hemin nanocomposite was synthesized using hemin and Fe₃O₄ with multi-walled carbon nanotubes (MWCNTs) by one-step hydrothermal methods. The as-prepared Fe₃O₄-MWCNTs@Hemin nanocomposites exhibited excellent peroxidase-like activities in the activation of H₂O₂. The mechanisms, kinetics, and catalytic performances of Fe₃O₄-MWCNTs@Hemin were systematically studied. Fe₃O₄-MWCNTs@Hemin can oxidize dopamine (DA) to dopaquinone in the presence of H₂O₂, and the intermediate products dopaquinone can further react with β-naphthol to generate a highly fluorescent derivative at 415 nm excitation wavelength. Therefore, an innovative fluorescence platform for the detection of DA was developed. The fluorescence intensity increased linearly with DA concentration in the range 0.33 to 107 μM, with a low detection limit of 0.14 μM. Due to the excellent activity, substrate universality, fast response, high selectivity, and sensitivity of Fe₃O₄-MWCNTs@Hemin, the proposed fluorescence method was used to analyze complex biological blood samples with a satisfactory result. It demonstrated the significant potential for developing effective and dependable fluorescent analytical platforms for preserving human health. Graphical abstract

[en] An undergraduate-level student experiment has been designed and implemented to measure the forward–backward asymmetry of the decay of the cosmic-ray muons, offering a pedagogical view to the parity violation in weak interactions. The detector system consists of six plastic scintillators installed vertically in row. The backward–forward asymmetry of the decay e⁻ and e⁺ with respect to the muon motion direction is correlated with the incident depth of the muon stopped in the scintillator. MC simulations have been carried out in order to better interpret the data and optimize the data analysis. The forward–backward asymmetry of 0.051 ± 0.027 is deduced for the decay of cosmic-ray muons in the energy range being studied. The results are consistent with the picture of parity violation in weak interactions. The experiment can be constructed by the senior undergraduate students under the guidance of the course teacher. (paper)

[en] The dissolution kinetics of cerussite in acidic sodium chloride solutions was investigated with respect to experimental variables such as particle size, stirring speed, sodium chloride concentration, hydrochloric acid concentration, and reaction temperature. Results show that leaching reagent concentration and reaction temperature have significant effects on the extraction of lead, whereas particle size and stirring speed have a relatively moderate effect on the leaching rate. The dissolution process followed the kinetic law of the shrinking core model, and a corresponding mixed control model was found suitable to represent the rate-controlling step. The apparent activation energy of this process was determined to be 40.46 kJ/mol, and a corresponding dissolution kinetic equation is also presented to describe the dissolution reaction

[en] In this work, a nano polythionine (NPTh)-based universal sandwich-type electrochemiluminescence (ECL) biosensor for sensitive and specific detection of the p16^INK4a gene using core-shell luminescent nanocomposites as excellent DNA labels was constructed. The NPTh electrode was prepared by in situ electropolymerization technique, which had a large surface area and was served as effective biosensing substrates for ssDNA1 immobilization by charge desorption. Meanwhile, tri(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺)/silver nanoparticles (AgNPs) doped gold (Au) core-shell nanocomposites ([email protected]) were utilized as excellent ssDNA2 labels. The construction of dsDNA was fabricated through a hybridization reaction of ssDNA1, p16^INK4a gene and [email protected] The change of ECL intensity on the NPTh electrode was found to have a linear relationship in respect to the logarithm of the p16^INK4a gene concentrations in the wide range of 1.0 × 10^-13~1.0 × 10⁻¹ M, with a detection limit of 0.05 p.M. (S/N = 3). The presented biosensing strategy may provide great potential in the assay of other clinically biomarkers.

[en] The design of highly active, Earth-abundant and stable electrocatalysts is important for efficient water splitting. In this work, we report the fabrication of RuP and Ru₂P nanoparticles supported on ordered macroporous N-doped carbon hollow spheres (RuP/H-NC and Ru₂P/H-NC) through a facile and scalable space-confined pyrolysis process. The RuP/H-NC catalyst exhibits Pt-like activity in alkaline electrolyte, by means of the macroporous structure with a larger specific area and more exposed active sites, as well as the synergistic effect between the RuP nanoparticles and N-doped carbon. Specifically, the RuP/H-NC catalyst yields superior hydrogen evolution reaction activity in terms of low overpotential of 19 mV in 1 M KOH to achieve a current density of 10 mA cm⁻² and excellent durability, outperforming Ru₂P/H-NC and most of the reported non-Pt catalysts. Further density function theory calculation reveals that RuP is more intrinsically active with favorable hydrogen adsorption Gibbs free energy than that of Ru₂P. (paper)