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91.
《中国化学快报》2020,31(8):2045-2049
Ethylene (C2H4), as a plant hormone, its emission can be served as an indicator to measure fruit quality. Due to the limited physiochemical reactivity of C2H4, it is a challenge to develop high performance C2H4 sensors for fruit detection. Herein, this paper presents a resistive-type C2H4 sensor based on Pd-loaded tin oxide (SnO2). The C2H4 sensing performance of proposed sensor are tested at optimum operating temperature (250 °C) with ambient relative humidity (51.9% RH). The results show that the response of Pd-loaded SnO2 sensor (11.1, Ra/Rg) is about 3 times higher than that of pristine SnO2 (3.5) for 100 ppm C2H4. The response time is also significantly shortened from 7 s to 1 s compared with pristine SnO2. Especially, the Pd-loaded SnO2 sensor possesses good sensitivity (0.58 ppm−1) at low concentration (0.05–1 ppm) with excellent linearity (R2 = 0.9963) and low detection limit (50 ppb). The high sensing performance of Pd-loaded SnO2 are attributed to the excellent adsorption and catalysis effects of Pd nanoparticle. Meaningfully, the potential applications of C2H4 sensor are performed for monitoring the maturity and freshness of fruits, which presents a promising prospect in fruit quality evaluation. 相似文献
92.
Luminescent quantum dots (QDs) are colloidal semiconductor nanocrystals consisting of an inorganic core covered by a molecular layer of organic surfactants. Although QDs have been known for more than thirty years, they are still attracting the interest of researchers because of their unique size-tunable optical and electrical properties arising from quantum confinement. Moreover, the controlled decoration of the QD surface with suitable molecular species enables the rational design of inorganic-organic multicomponent architectures that can show a vast array of functionalities. This minireview highlights the recent progress in the use of surface-modified QDs – in particular, those based on cadmium chalcogenides – as supramolecular platforms for light-related applications such as optical sensing, triplet photosensitization, photocatalysis and phototherapy. 相似文献
93.
Mr. Kingshuk Mukhuti Dr. V. N. K. B. Adusumalli Mr. Heramba V. S. R. M. Koppisetti Prof. Bhavtosh Bansal Prof. Venkataramanan Mahalingam 《Chemphyschem》2020,21(15):1731-1736
Precise assessment of temperature is crucial in many physical, technological, and biological applications where optical thermometry has attracted considerable attention primarily due to fast response, contactless measurement route, and electromagnetic passivity. Rare-earth-doped thermographic phosphors that rely on ratiometric sensing are very efficient near and above room temperature. However, being dependent on the thermally-assisted migration of carriers to higher excited states, they are largely limited by the quenching of the activation mechanism at low temperatures. In this paper, we demonstrate a strategy to pass through this bottleneck by designing a linear colorimetric thermometer by which we could estimate down to 4 K. The change in perceptual color fidelity metric provides an accurate measure for the sensitivity of the thermometer that attains a maximum value of 0.86 K−1. Thermally coupled states in Er3+ are also used as a ratiometric sensor from room temperature to ∼140 K. The results obtained in this work clearly show that Yb3+−Er3+ co-doped NaGdF4 microcrystals are a promising system that enables reliable bimodal thermometry in a very wide temperature range from ultralow (4 K) to ambient (290 K) conditions. 相似文献
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95.
Electrochemistry belongs to an important branch of chemistry that deals with the chemical changes produced by electricity and the production of electricity by chemical changes. Therefore, it can not only act a powerful tool for materials synthesis, but also offer an effective platform for sensing and catalysis. As extraordinary zero‐dimensional materials, carbon‐based quantum dots (CQDs) have been attracting tremendous attention due to their excellent properties such as good chemical stability, environmental friendliness, nontoxicity and abundant resources. Compared with the traditional methods for the preparation of CQDs, electrochemical (EC) methods offer advantages of simple instrumentation, mild reaction conditions, low cost and mass production. In return, CQDs could provide cost‐effective, environmentally friendly, biocompatible, stable and easily‐functionalizable probes, modifiers and catalysts for EC sensing. However, no specific review has been presented to systematically summarize both aspects until now. In this review, the EC preparation methods of CQDs are critically discussed focusing on CQDs. We further emphasize the applications of CQDs in EC sensors, electrocatalysis, biofuel cells and EC flexible devices. This review will further the experimental and theoretical understanding of the challenges and future prospective in this field, open new directions on exploring new advanced CQDs in EC to meet the high demands in diverse applications. 相似文献
96.
Karolina Maleckait Domantas Narkevi
ius Rugil
ilnait Jelena Dodonova-Vaitknien Stepas Toliautas Sigitas Tumkevi
ius Aurimas Vyniauskas 《Molecules (Basel, Switzerland)》2022,27(1)
Mapping microviscosity, temperature, and polarity in biosystems is an important capability that can aid in disease detection. This can be achieved using fluorescent sensors based on a green-emitting BODIPY group. However, red fluorescent sensors are desired for convenient imaging of biological samples. It is known that phenyl substituents in the position of the BODIPY core can shift the fluorescence spectra to longer wavelengths. In this research, we report how electron-withdrawing (EWG) and -donating (EDG) groups can change the spectral and sensory properties of -phenyl-substituted BODIPYs. We present a trifluoromethyl-substituted (EWG) conjugate with moderate temperature sensing properties and a methoxy-substituted (EDG) molecule that could be used as a lifetime-based polarity probe. In this study, we utilise experimental results of steady-state and time-resolved fluorescence, as well as quantum chemical calculations using density functional theory (DFT). We also explain how the energy barrier height () for non-radiative relaxation affects the probe’s sensitivity to temperature and viscosity and provide appropriate ranges for the best possible sensitivity to viscosity and temperature. 相似文献
97.
D形光纤Bragg光栅弯曲灵敏度的理论和实验研究 总被引:2,自引:1,他引:1
用材料力学理论分析了D形光纤Bragg光栅(D-shaped fiber Bragg grating,D-FBG)以及常规光纤Bragg光栅由弯曲引起的轴向应变,得到了光栅Bragg波长漂移的弯曲敏感特性.实验结果和理论计算结果基本相符.与常规FBG相比,该D-FBG的弯曲灵敏度要高近80倍.因此D-FBG可以直接应用于弯曲形变的测量,以及间接应用于压力、加速度等物理量的测量.理论分析和实验结果对采用该类型光纤光栅的器件和传感系统的设计具有参考意义. 相似文献
98.
对基于(C—H)+…X-氢键类型的阴离子识别以及识别过程所引起的光化学传感和电化学传感的研究进展进行了评述. 相似文献
99.
中高分辨力遥感图像中飞机目标自动识别算法研究 总被引:2,自引:0,他引:2
提出了一种中高分辨力的航空航天遥感图像中飞机目标快速自动识别的新算法。在分割和分类过程中充分利用飞机目标的先验知识,提出了一种改进区域分割方法,并应用树分类器对飞机目标进行自动识别。所提出的改进区域分割方法较好地实现了区域分割中阈值的准确自动选取,克服了复杂背景图像中小目标的全局阈值自动分割的失效问题。采用二叉树分类器,通过提取简单的目标几何特征,分层进行种类识别,提高了识别速度,降低了漏检率和虚警率。运用该方法进行了实验。结果表明,识别率达到了100%。 相似文献
100.