Yifan Xu  Bin Zhou  Chao Zhuang  Jianhua Zhou  Huanjun Chen  Shaozhi Deng 《Advanced Optical Materials》2020,8(15)

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Ze-Nan Hu;Fangya Guo;Xiuxiu Zhang;Jie Yu;Yaru Yin;Biying Zhang;Hua-Jun Chen;Meijia Chang;Yiming Wang;Yalei Miao;Lan Zhang;Wenjie Tian;Hong-bin Sun; 《应用有机金属化学》2024,38(11):e7685

Hydrazine hydrate as a hydrogen source has a good effect on nitro reduction, but overuse has environmental toxicity and is prone to over-hydrogenation, resulting in low selectivity. Herein, we report a magnetically separable Rh/Fe3O4 (1.26 wt%) catalyst containing an optimal Rh content that can completely convert 3-nitrostyrene to 3-vinylaniline (> 99% selectivity) using a stoichiometric molar ratio of hydrazine hydrate (-NO2:N2H4·H2O = 1:1.5). This is due to the synergy between Rh and Fe3O4 and the natural selectivity of N2H4·H2O for nitro. The synergy can reduce the activation energy of the reaction (36.6 kJ/mol), increasing the reduction rate of nitro group and avoiding the combination of active hydrogen species (H*) to H2 as well as the hydrogenation of N2H4 to NH3. Moreover, the active H* produced by N2H4·H2O is different from that produced by H2, and excess dose of N2H4 will inevitably yield H2 thus decline the selectivity.  相似文献   

    

Florentin Coppey  Cédric Schelling  Jean-Luc Veuthey  Pierre Esseiva 《Helvetica chimica acta》2023,106(8):e202300052

In the past few years, there has been significant interest within the forensic community regarding the deployment of portable solutions that provide real-time results. This article introduces an innovative technology or technology architecture that enables the integration of a handheld device, specifically, Viavi MicroNIR, with a cloud-based system. This cloud system encompasses a server responsible for data processing and a mobile application acting as a user interface. To demonstrate the transformative impact of this technology on field operators, the analysis of cannabis specimens has been utilized. System's capacity to distinguish between CBD-type and THC-type cannabis has been particularly highlighted, along with the remarkable congruence observed between the near-infrared (NIR) spectra and the reference analytical method involving ultra-high-performance liquid chromatography (UHPLC) The article will present the advantages of this application primarily focusing on its potential to alleviate the burden on laboratories by expediting routine illicit drug analysis. Viavi MicroNIR technology provides laboratory personnel with additional time to handle more complex cases, thereby enhancing overall efficiency.  相似文献   

    

Somdeb Chanda  Ajanto Kumar Hazarika  Navnil Choudhury  Sk Anarul Islam  Rishabh Manna  Santanu Sabhapondit  Bipan Tudu  Rajib Bandyopadhyay 《Journal of Chemometrics》2019,33(10)

Caffeine is an important component that determines the quality of tea, and its rapid estimation is very much needed for the industry. In this pursuit, a near‐infrared (NIR) spectroscopy‐based technique for the estimation of caffeine is developed and presented in this paper. On the basis of responses of the different bonds present in caffeine, four specific wavelength windows—(a) 1075 to 1239.5 nm (C―H stretch second overtone); (b) 1339.25 to 1440.75 nm (C―H stretch and C―H deformation); (c) 1640.25 to 1700 nm (C―H stretch first overtone, ═CH & amp; ―CH₃ asymmetric); and (d) 900 to 1700 nm (whole range of the spectrometer)—were analyzed in details for model development and to obtain the effective wavelength (EW). Five different preprocessing techniques followed by two regression techniques—(a) the partial least‐squares (PLS) and (b) the support vector regression (SVR) were implemented on raw data for analysis. Comparing all the models, the wavelength band of 1075 to 1239.5 nm and 1339.25 to 1440.75 nm were found to produce satisfactory results. The best discrimination result was obtained using the combination of standard normal variate (SNV) preprocessing with SVR at the 1075 to 1239.5 nm wavelength region. The SVR regression with 105 samples in the training set and 15 samples in the testing set resulted in the performance parameters as RMSECV = 0.134, RMSEP = 0.069, r_cv² = 0.869, r_p² = 0.65, and RPD = 5.626 at 1075 to 1239.5 nm, whereas the PLS model produced the best RMSECV = 0.287, RMSEP = 0.077, r_cv² = 0.637, r_p² = 0.675, and RPD = 5.218 at 1339.25 to 1440.75‐nm wavelength band.  相似文献   

    

Anirban Dutta  Rakesh Kumar Behera  Poulami Pal  Sujoy Baitalik  Narayan Pradhan 《Angewandte Chemie (International ed. in English)》2019,58(17)

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Xiaojie Mu  Qimin Zhang 《Mathematical Methods in the Applied Sciences》2019,42(3):767-789

Medical treatment and vaccination decisions are often sequential and uncertain. Markov decision process is an appropriate means to model and handle such stochastic dynamic decisions. This paper studies the near‐optimality of a stochastic SIRS epidemic model that incorporates vaccination and saturated treatment with regime switching. The stochastic model takes white noises and color noise into account. We first prove some priori estimates of the susceptible, infected, and recovered populations. Moreover, we establish some sufficient and necessary conditions of the near‐optimality by Pontryagin stochastic maximum principle. Our results show that the two kinds of environmental noises have great impacts on the infectious diseases. Finally, we illustrate our conclusions through numerical simulations.  相似文献   

    

Huangsheng Yu  Xianwei Sun  Dianhua Wu  R. Julian R. Abel 《组合设计杂志》2019,27(1):27-41

Necessary conditions for the existence of a super‐simple, decomposable, near‐resolvable ‐balanced incomplete block design (BIBD) whose 2‐component subdesigns are both near‐resolvable ‐BIBDs are (mod ) and . In this paper, we show that these necessary conditions are sufficient. Using these designs, we also establish that the necessary conditions for the existence of a super‐simple near‐resolvable ‐RBIBD, namely (mod ) and , are sufficient. A few new pairwise balanced designs are also given.  相似文献   

    

Yali Sun  Ivan Sinev  Anastasia Zalogina  Eduard Ageev  Hadi Shamkhi  Filipp Komissarenko  Ivan Morozov  Sergey Lepeshov  Valentin Milichko  Sergey Makarov  Ivan Mukhin  Dmitry Zuev 《Laser u0026amp; Photonics Reviews》2019,13(2)

Tailoring of the near‐field properties of the nanostructures is a significant task for the control of radiation of nanoscale light sources as well as for sensing applications. Generally, this task is solved in plasmonic oligomers on the fabrication step by the choice of geometry or by controlling the excitation light during the experiments. Here, the pronounced modification of the near‐field pattern in hybrid gold‐silicon oligomers by femtosecond laser reshaping by visualizing it with aperture‐type near‐field optical microscope is demonstrated. This effect correlates with a moderate red‐shift of the broadband magnetic dipole resonance of the structure that occurs upon reshaping the gold component of the oligomers. The proposed all‐optical near‐field reconfiguration approach makes hybrid oligomers a promising platform for on‐demand engineering of local field enhancement in metadevices for data recording and sensing.  相似文献   

    

Tam Duy Nguyen  Loo Pin Yeo  Tan Chiew Kei  Daniel Mandler  Shlomo Magdassi  Alfred Iing Yoong Tok 《Advanced Optical Materials》2019,7(8)

Renewable energy technology and effective energy management are the most crucial factors to consider in the progress toward worldwide energy sustainability. Smart window technology has a huge potential in energy management as it assists in reducing energy consumption of indoor lighting and air‐conditioning in buildings. Electrochromic (EC) materials, which can electrically modulate the transmittance of solar radiation, are one of the most studied smart window materials. In this work, highly transparent SnO₂ inverse opal (IO) is used as the framework to electrochemically deposit amorphous WO₃ layer to fabricate hybrid SnO₂–WO₃ core–shell IO structure. The hybrid structure is capable of effective near infrared (NIR) modulation while maintaining high visible light transparency in the colored and bleached states. By varying the initial diameter of the polystyrene (PS) opal template and the WO₃ electrodeposition time, optimal results can be obtained with the smallest PS diameter of 392 nm and 180 s WO₃ electrodeposition. In its colored state, the 392‐SnO₂–WO₃‐180 core–shell IO structure shows ≈70% visible light transparency, 62% NIR blockage at 1200 nm, and ≈15% drop in NIR blocking stability after 300 cycles. The SnO₂–WO₃ core–shell IO structure in this study is a promising EC material for advanced smart window technology.  相似文献   

    

Fan Hong  Richard Blaikie 《Advanced Optical Materials》2019,7(14)

Plasmonic lithography has received extensive attention as both a potential candidate for next generation lithography and as an interesting testbed to test the fundamental resolution limits of optical imaging and patterning. Owing to the utilization of the otherwise lost evanescent near fields containing high frequency information, surface plasmon‐based lithographic techniques can break the diffraction limit in conventional photolithography; resolution down to approximately 20 nm using visible light has been experimentally demonstrated, and theoretical studies have analyzed methods that have the potential for creating nanopatterns with sub‐10 nm resolution. This paper reviews the research progress and various modalities of plasmonic lithography, addresses current obstacles and problems, and provides an outlook for practical application.  相似文献