Domain,dielectric and optical studies in antiferroelectric (Pb,La) (Zr,Sn, Ti)O3 single crystals

Antiferroelectric (Pb, La) (Zr, Sn, Ti)O₃ (PLZST) single crystals have been successfully grown by flux method using PbO–PbF₂–B₂O₃ as the flux. The obtained crystals are pale yellow in color and translucent. Domain structures, dielectric constants and optical transmission measurements have been performed on the 〈001〉-oriented PLZST single crystals. Two types of domains, namely, 90° and 180° domains, are observed. The extinction of 90° domains at P/A: 0° reveals a tetragonal structure in the crystal. The sequence of phase transitions from antiferroelectric to ferroelectric and then paraelectric has been established with increasing temperature. According to the modified Curie–Weiss relationship, the PLZST crystal is in an intermediate state between normal and relaxor antiferroelectrics. The broad optical transparent region (from 0.4 to 7.0 μm) and high optical transmittance (up to 65%) indicate that PLZST crystals are promising for optical uses.     

Laser spot position dependence in photothermal mode cooling of a microcantilever

We explore the laser spot position (LSP) dependence of photothermal mode cooling in a microcantilever-based Fabry-Perot cavity. Experiments on photothermal cooling demonstrate that the direction of photothermal backaction on the first two cantilever modes is LSP dependent, which can be either parallel or antiparallel. A theoretical analysis of this LSP-dependent effect identifies the parallel and the antiparallel coupling regions along the lever. Simulation results are in quantitative agreement with our experimental observations. We conclude that the cooling limit imposed by photothermal mode coupling can be surmounted by operating in the parallel coupling region.     

Coherent detection of THz waves based on THz-induced time-resolved luminescence quenching in bulk gallium arsenide

A kind of photoluminescence quenching, in which the time-resolved photoluminescence is modulated by a THz pulse, has been theoretically investigated by performing the ensemble Monte Carlo method in bulk gallium arsenide (GaAs) at room temperature. The quenching ratio could reach up to 50% under a strong THz field (100 kV/cm). The range in which luminescence quenching is linearly proportional to the THz field could be over 60 kV/cm. On the basis of these results, a principle for THz modulation and coherent detection is proposed.     

Derivation of the near-surface dielectric function of amorphous silicon from photoelectron loss spectra

The near-surface dielectric function ε(?ω) of hydrogenated amorphous silicon (a-Si:H) films has been derived from X-ray photoelectron energy-loss spectra, over the energy range 0–40 eV. Removal of low lying single-electron excitations is a prerequisite step to proceed to the derivation of the single plasmon energy loss function Im[? 1/ε(?ω)] due to collective electron oscillations. Several methods are compared to separate interband transitions from bulk or surface plasmons excitation. The shape of interband excitation loss in the range 1–10 eV can be described by a Henke function; alternatively, its removal using a sigmoid weighting function is a low-noise and reliable method. After deconvolution of multiple plasmon losses and self-consistent elimination of surface plasmon excitation, the single plasmon loss distribution allows recovery of optical (ellipsometry) data measured in the near-UV to visible range.     

Consolidation and mechanical properties of Cu46Zr42Al7Y5 metallic glass by spark plasma sintering

Cu₄₆Zr₄₂Al₇Y₅ metallic glass with nearly 100% relative density was obtained by spark plasma sintering (SPS) with a diameter of 15 mm, which was larger than the largest size of 10 mm for the as-cast specimen. The fracture strength of the sintered specimen reached 2044 MPa, which was 15% higher than that of the as-cast Cu₄₆Zr₄₂Al₇Y₅ glassy specimen. The densification and compressive properties of the sintered specimens were related to sintering temperature. Structural changes of the specimens sintered at various sintering temperatures resulted in the difference of macro-mechanical properties.     

快速床动力学统一模型Ⅱ:上部稀相与下部浓相固含率的预报

在前文建立的分相共存快速床动力学模型的基础上,对分相模型中存在颗粒团聚物时的上升稀相进行了受力分析。以有限直径提升管中颗粒终端速度的修正,导出了上升稀相受力关于等效管径与浓稀相滑移速度的修正表达式。将本模型预报的上部稀相固含率与已有的实验数据经验关联式进行了对比,并根据所得结果初步优化了模型参数(k=8,n=6)。进而,根据所得模型参数计算了下部浓相固含率随曳力函数f(ε)的变化规律;与李佑楚经验关联式相比,同样具有合理的一致性。本文工作进一步验证了快速床动力学统一模型的整体合理性。     

A sensitive fluorescence strategy for telomerase detection in cancer cells based on T7 exonuclease-assisted target recycling amplification

A sensitive fluorescence strategy based on T7 exonuclease-assisted target recycling amplification was developed for telomerase detection in cancer cells. The novel strategy improved the fluorescence signal and sensitivity compared with the previously reported methods.     

Fluorescence turn-on detection of hypochlorous acid via HOCl-promoted dihydrofluorescein-ether oxidation and its application in vivo

We report three new water-soluble dihydrofluorescein-ether probes FCN1, FCN2 and FCN3 for the detection of hypochlorous acid (HOCl), which were designed on the basis of a specific HOCl-promoted oxidation reaction. This work also provided a useful method to monitor the accumulated HOCl in specific organelles using a zebrafish model.     

Evaluation of thermal hazard for lauroyl peroxide by VSP2 and TAM III

When above certain temperature limits, lauroyl peroxide is an unstable material. If the thermal source cannot be properly governed during any stage in the preparation, manufacturing process, storage or transport, runaway reactions may inevitably be induced immediately. In this study, the influence of runaway reactions on its basic thermal characteristic was assessed by evaluating thermokinetic parameters, such as activation energy (E _a) and frequency factor (A) by thermal activity monitor III (TAM III). This was achieved under five isothermal conditions of 50, 60, 70, 80, and 90?°C. Vent sizing package 2 (VSP2) was employed to determine the maximum pressure (P _max), maximum temperature (T _max ), maximum self-heating rate ((dT?dt ^?1)_max), maximum pressure rise rate ((dP?dt ^?1)_max), and isothermal time to maximum rate ((TMR)_iso) under the worst case. Results of this study will be provided to relevant plants for adopting best practices in emergency response or accident control.     

Effects of a natural prolyl oligopeptidase inhibitor, rosmarinic acid, on lipopolysaccharide-induced acute lung injury in mice

Rosmarinic acid (RA), a polyphenolic phytochemical, is a natural prolyl oligopeptidase inhibitor. In the present study, we found that RA exerted potent anti-inflammatory effects in in vivo models of acute lung injury (ALI) induced by lipopolysaccharide (LPS). Mice were pretreated with RA one hour before challenge with a dose of 0.5 mg/kg LPS. Twenty-four hours after LPS was given, bronchoalveolar lavage fluid (BALF) was obtained to measure pro-inflammatory mediator and total cell counts. RA significantly decreased the production of LPS-induced TNF-a, IL-6, and IL-1β compare with the LPS group. When pretreated with RA (5, 10, or 20 mg/kg) the lung wet-to-dry weight (W/D) ratio of the lung tissue and the number of total cells, neutrophils and macrophages in the BALF were decreased significantly. Furthermore, RA may enhance oxidase dimutase (SOD) activity during the inflammatory response to LPS-induced ALI. And we further demonstrated that RA exerts anti-inflammation effect in vivo models of ALI through suppresses ERK/MAPK signaling in a dose dependent manner. These studies have important implications for RA administration as a potential treatment for ALI.