Double-layer liquid crystal lens array with composited dielectric layer

ABSTRACT

A double-layer liquid crystal (LC) lens array with composited dielectric layer is proposed. In our design, a spatially non-uniform electric field is generated between the strip electrodes, resulting in a gradient refractive index distribution in the LC layer. Since the upper and lower parts of the LC lens array both adopt a composite dielectric layer, the operation voltage of the LC lens array is effectively reduced. In terms of LC lenslet, the double-layer design doubles the phase difference between the centre and the periphery of the LC layer, thereby reducing the focal length of the LC lens array. In addition, the shortest focal length (~1.78 mm) of the LC lens array is obtained at V = 3.3 V, and the LC lens array has a large focusing range.     

Dielectronic recombination at low energy range with Boron-like Ar13+at the CSRm

In order to extend the dielectronic recombination (DR) experiments from the main cooler storage ring CSRm with intermediate charge state ions to the experimental cooler storage ring CSRe with highly charged ions and even radioactive ions, a test electron-ion recombination experiment of B-like Ar¹³⁺ ions was performed with a section of the new electron beam energy detuning system, which will be installed at the CSRe. We present the measured and also the calculated DR spectra for the ∆n = 0 resonances from 0 to 3 eV. The experimental results agree very well with the previous DR experimental data from CRYRING, and the energy resolution reached 30 meV full width at half maximum. This test experiment demonstrates that the reliability and stability of the newly developed electron beam energy detuning system are satisfactory for the upcoming DR experiments at the CSRe. However, we found large discrepancies between the experimental result and the calculation in both resonance positions and the intensities of the recombination spectrum below 0.7 eV, which indicate that precise calculation of the DR spectrum of multielectron ions is still a challenge.     

The distillation behavior of fluorides in LiCl–KCl molten salt

Journal of Radioanalytical and Nuclear Chemistry - The distillation behaviors of some fission product fluorides in LiCl–KCl system were investigated. For rare earth element, the corresponding...     

Ionic liquid-assisted synthesis of defect-rich BiOI with controllable structure and high surface area for excellent visible-light photocatalytic activity

In this study, BiOI materials with controllable structure are designed by using ionic liquid as I source and template to create the surface oxygen defects, thus promoting the photogenerated carrier migration and enhancing the photocatalytic activity. The texture of BiOI is controlled by adjusting the pH values of reaction mixture and the corresponding formation mechanism is also explored based on the self-assembly behavior of ionic liquid. It is found that the sample BiOI-7 possesses the ultrathin nanosheets (2 ~ 4 nm) and abundant surface oxygen defects which are beneficial for accelerating carrier transfer and facilitating photocatalytic degradation. The photocatalytic activity of as-prepared BiOI is studied by using Rhodamine B (RhB), methyl orange (MO) and Bisphenol A (BPA) as target pollutants, respectively. Besides, water splitting reactions were also used to further check the photocatalytic activity. BiOI samples exhibit the enhanced photocatalytic activity than bulk BiOI and g-C₃N₄ obtained by calcination of melamine. Especially, 92% of bisphenol A (BPA) can be degraded under light irradiation within 1 hr by using only 5 mg of BiOI-7 nanosheets, which is superior than most counterparts reported so far. This rapidly synthetic route can be applied in fabrication of other novel materials with diverse morphology and porous structure.     

In situ Synthesis of Biomimetic Silica Nanofibrous Aerogels with Temperature-Invariant Superelasticity over One Million Compressions

Resilient and compressible three-dimensional nanomaterials comprising polymers, carbon, and metals have been prepared in diverse forms. However, the creation of thermostable elastic ceramic aerogels remains an enormous challenge. We demonstrate an in situ synthesis strategy to develop biomimetic silica nanofibrous (SNF) aerogels with superelasticity by integrating flexible electrospun silica nanofibers and rubber-like Si−O−Si bonding networks. The stable bonding structure among nanofibers is in situ constructed along with a fibrous freeze-shaping process. The resultant SNF aerogels exhibit integrated properties of ultralow density (>0.25 mg cm⁻³), temperature-invariant superelasticity up to 1100 °C, and robust fatigue resistance over one million compressions. The ceramic nature also endows the aerogels with fire resistance and ultralow thermal conductivity. The successful synthesis of the SNF aerogels opens new pathways for the design of superelastic ceramic aerogels in a structurally adaptive and scalable form.     

Vacancy Engineering of Iron-Doped W18O49 Nanoreactors for Low-Barrier Electrochemical Nitrogen Reduction

The electrochemical nitrogen reduction reaction (NRR) is a promising energy-efficient and low-emission alternative to the traditional Haber–Bosch process. Usually, the competing hydrogen evolution reaction (HER) and the reaction barrier of ambient electrochemical NRR are significant challenges, making a simultaneous high NH₃ formation rate and high Faradic efficiency (FE) difficult. To give effective NRR electrocatalysis and suppressed HER, the surface atomic structure of W₁₈O₄₉, which has exposed active W sites and weak binding for H₂, is doped with Fe. A high NH₃ formation rate of 24.7 μg h⁻¹ mg_cat⁻¹ and a high FE of 20.0 % are achieved at an overpotential of only −0.15 V versus the reversible hydrogen electrode. Ab initio calculations reveal an intercalation-type doping of Fe atoms in the tunnels of the W₁₈O₄₉ crystal structure, which increases the oxygen vacancies and exposes more W active sites, optimizes the nitrogen adsorption energy, and facilitates the electrocatalytic NRR.     

Generation of α-Boryl Radicals and Their Conjugate Addition to Enones: Transition-Metal-Free Alkylation of gem-Diborylalkanes

A transition-metal-free method for the alkylation of gem-diborylalkanes with α,β-unsaturated ketones has been developed. It is demonstrated that the α-boryl radicals can be generated efficiently from gem-diborylalkanes with the aid of catechol and oxidants. The α-boryl radicals formed through such process can be engaged in conjugate addition reaction with α,β-unsaturated ketones. This transformation is a straightforward method for the synthesis of γ-borylketones.     

Tuning Diradical Properties of Boron-Containing π-Systems by Structural Isomerism

Tuning diradical character is an important topic for organic diradicaloids. Herein, we report the precise borylation enabling structural isomerism as an effective strategy to modulate diradical character and thereby properties of organic diradicaloids. We synthesized a new B-containing polycyclic hydrocarbon that has the indeno[1,2-b]fluorene π-skeleton with the β-carbons bonding to two boron atoms. Detailed theoretical and experimental results show that this bonding pattern leads to its distinctive electronic structures and properties in comparison to that of its isomeric molecule. This molecule has the efficient conjugation between boron atoms and π-skeleton, resulting in downshifted LUMO and HOMO levels. Moreover, it exhibits smaller diradical character and thereby inhibited diradical properties, such as significantly blue-shifted light absorption, larger energy bandgap and weak para-magnetic resonance. Notably, this B-containing polycyclic hydrocarbon possesses much stronger Lewis acidity and its Lewis acid-base adducts display enhanced diradical character, demonstrating the positive effects of Lewis coordination on modulating diradical performance.     

A pico-HPLC-LIF system for the amplification-free determination of multiple miRNAs in cells

MicroRNAs are a class of important biomarkers,and the simultaneous detection of multiple miRNAs can provide valuable information about many diseases and biological processes.Amplification-free determination has been developed for the analysis of multiple miRNAs because of its characteristic low cost and high fidelity.Herein,a method for the amplification-free analysis and simultaneous detection of multiple miRNAs based on a so-called pico-HPLC-LIF system is described.In this process,a bare open capilla ry with an inner diameter of 680 nm is used as a sepa ration column for a sample volume of several hundreds of femtoliters(300 fL),followed by separation and detection.The technique has a zeptomolar limit of detection.The method was applied to detect cellular miRNA from adenocarcinomic human alveolar basal epithelial(A549) cell extracts,and the simultaneous detection of the mir-182,miR-155,and let-7 a was achieved.The results showed that the expression of mir-182 and miR-155 was up-regulated and that of let-7 a was down-regulated in A549 cells.This method for multiple miRNAs detection is expected to have broad applications in miRNA-based disease diagnosis,prognosis,treatment,and monitoring.