查看更多>>摘要：Inorganic oxides doped with rear earth(RE) have attracted much interest because of their outstanding optical properties. In this paper, the BaWO4:Yb3+/Er3+/Nd3+ phosphors were successfully prepared by typical solid state method. The crystalline structure of the samples was characterized through X-ray diffraction(XRD). The morphology of that was demonstrated with field emission scanning electron microscopy (FE-SEM). Under 980 nm excitation, the BaWO4:Yb3+/Er3+/Nd3+ phosphor presented four typical emissions at green(524-550 nm, Er3+), red(similar to 655 nm, Er3+), near infrared(similar to 710 nm, similar to 820 nm, Nd3+). Furthermore, the temperature sensing properties of the samples were investigated in the temperature range of 303-573 K. The fluorescence intensity ratio(FIR) technique based on thermal and non-thermal coupled levels was applied to analyse the sensing performances. For BaWO4:Yb3+/Er3+/Nd3+ phosphor, the maximum absolute sensitivity reached 0.0423 K-1 at 303 K, which is based on H-2(11/2)(Er3+) and F-4(7/2)(Nd3+) levels. The repeatability of temperature response also was proved through four cold and heat cycles. The above result indicated that the BaWO4:Yb3+/Er3+/Nd3+ phosphor would be a promising temperature sensing materials.& nbsp;(C)& nbsp;2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Integrating the advantages of catalytic hairpin components and multi-foot DNA walker, we designed a 16S rRNA detection probe template for pathogen bacteria, which utilizes DNA ligation quencher and dual catalytic hairpin@DNA walker to induce signal recovery. The dual catalytic hairpin@DNA walker uses the walking position of the target on the AuNP as a foothold to promote the reaction, so that the biosensing of the low-abundance target sequence can induce signal recovery. During the entire experiment, no enzyme is required, which can avoid the limitation of enzyme degradation under unfavorable conditions and the inability to detect the target. Most importantly, the detection template has the advantages of high sensitivity, and its detection limit is significantly better than that of single hairpin DNA walker probe. As the detection system can sensitively and rapidly detect its targeted bacteria and not rely on any enzyme and sophisticated instrumentation, it has great potential for sensitive and specific pathogenic bacteria detection.
查看更多>>摘要：The application of two-trace two-dimensional (2T2D) correlation analysis to a number of spectra consisting of more than a simple pair is explored, especially when such spectra are randomly collected without knowing the sampling order. Calculation and interpretation of 2T2D correlation spectra are briefly reviewed, and a systematic procedure to identify the set of characteristic bands, which are mutually asynchronous and least overlapped with each other, is described. 2T2D correlation is applied to individual spectra by selecting a representative reference spectrum, such as the average of the whole dataset. A slice of an asynchronous 2T2D spectrum at a characteristic band is devoid of the spectral contribution from the species represented by the band. Since 2T2D analysis may be applied to the whole set of spectra, and each 2T2D asynchronous spectrum yields a set of slices for different characteristic bands, it is possible to generate a series of 2T2D slices obtained at a given characteristic band. By applying the generalized 2D correlation or a successive 2T2D analysis to such slices, one can obtain excellent estimates of the pure component spectra of the mixture, which are comparable to the results from other curve resolution techniques.(c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：A new ruthenium complex-based luminescent probe Ru-impa for Cu2+ and pH detection has been synthesized and characterized. Ru-impa could rapidly and selectively detect Cu2+ in aqueous solutions and the working pH ranges from weakly acidic to alkaline. The detection limit calculated using the S/N and S/B ratio was 24.7 nM and 3.4 mu M, respectively. The test strips for practical detecting application were also prepared and the actual detection limit in drinking water was found to be 3 mu M, which is lower than the WHO-guided drinking water limit (30 mu M) and the upper limit of human serum free copper content (1.7-3.9 mu M). Luminescence imaging study showed that Ruimpa could monitor Cu2+ level fluctuation in the cells. In addition, Ruimpa also shows a sensitive on-off luminescence response when pH > 10, indicating that it can also be used as a pH sensor under extremely alkaline conditions. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Eucommia ulmoides is an important and valuable traditional Chinese medicine with various medical functions, and has been widely used as health food in China, Japan, South Korea and other Asian countries for many years. The efficacy and quality of E. ulmoides are closely associated with the geographical origin. In this work, the potential of excitation-emission matrix (EEMs) fluorescence coupled with chemometric methods was investigated for simple, rapid and accurate for identification E. ulmoides from different geographical origins. Parallel factor analysis (PARAFAC) was applied for characterizing the fluorescence fingerprints of E. ulmoides samples. Moreover, k-nearest neighbor (kNN), principal component analysis linear discriminant analysis (PCA-LDA) and partial least squares discriminant analysis (PLS-DA) models were used for the classification of E. ulmoides samples according to their geographical origins. The results showed that kNN model was more suitable for identification of E. ulmoides samples from different provinces. The kNN model could identify E. ulmoides samples from eight different geographical origins with 100% accuracy on the training and test sets. Therefore, the proposed method was available for conveniently and accurately determining the geographical origin of E. ulmoides, which can expect to be an attractive alternative method for identifying the geographic origin of other traditional Chinese medicines. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：A new ferrocene appended linear donor -p-acceptor (D-pi-A) type 1,8-naphthalimide chromophores [FcPhNap-n-butyl (1) and Fc(Ph)(2)Nap-n-butyl (2)] have been synthesized and characterized using various analytical and spectroscopic techniques. The chromophores 1 and 2 show the one-electron transfer process, which was examined through cyclic voltammetric (CV) method. The solvatochromic studies show red shift by increasing the solvent polarity from non-polar to polar for both the chromophores 1 and 2, due to the better stabilization of the more polarized excited state than the ground state in the polar solvent. The fluorescence studies show low fluorescence emission, which was enhanced by aggregation in THF/water mixture when the water ratio is increased upto 60%, due to the restricted intramolecular rotation (RIR) process in the aggregated state. Also, the quantum yield increases 3.4 (1) and 6.8 (2) times in the aggregation induced enhanced emission (AIEE) state than THF solution for both the chromophores [THF/AIEE = 0.05/0.17 for 1 and 0.03/0.22 for 2]. The second-order non-linear optical properties of the chromophores 1 and 2 were studied using Kurtz and Perry powder technique, chromophore 2 shows 1.2 times higher SHG efficiency than 1, owing to the presence of additional phenyl group in 2, which further supports the effective charge transfer process from donor to acceptor. Furthermore, optical and non linear optical properties of chromophores 1 and 2 were analyzed by DFT/TD-DFT calculations using different functionals (B3LYP, long-range corrected CAM-B3LYP and LC-BLYP) with 6-31+G** level of theory. The B3LYP functional shows higher hyperpolarizability values [beta(0) = 109.2 x 10(-30) esu (1), 299.7 x 10(-30) esu (2)], due to the overestimation of the dipole moment, polarizability and hyperpolarizabilities between the donor-1t-acceptor systems in B3LYP-hybrid functional, which leads to incorrect long-range charge transfer.(C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The feasibility of laser cooling of AuF molecule and its cation are investigated from vibrational and rotational perspectives. The spectroscopy of AuF molecule and AuF+ molecular cation are obtained by the method of multireference configuration interaction plus Davidson correction (MRCI + Q) and spin-orbit coupling (SOC) effect. On account of the accurate molecular spectroscopy and the transition dipole moment, the Franck-Condon factors and radiative lifetimes of AuF molecule and AuF+ molecular cation are calculated. Comparing the criterias of laser cooling candidate molecules, the AuF is an excellent candidate for laser cooling and while AuF+ is not sutable. The b3P0+ M X1R+ 0+transition of AuF is selected for laser cooling and an optical cycling scheme is proposed. The scheme possesses highly diagonally FranckCondon factors and the scattered photons achieve - 104. Furthermore, the rotational transition analysis is also included in our work and found that its Franck Condon factors and Einstein coefficients are undistorted. Our work could provide theoretical support and accelerate the laser cooling of AuF molecules in experiments.
查看更多>>摘要：Effects of montmorillonite (MMT) on the crystallization behavior of poly(L-lactic acid) (PLLA) were investigated by variable-temperature FTIR spectroscopy. The variations of carbonyl band (1800-1720 cm(-1)) of different PLLA/MMT nanocomposites were focused due to its strong intensity and the involved abundant structure information. Difference spectrometry was used to evaluate the structural variations of PLLA after introducing MMT, and perturbation correlation moving window two-dimensional analysis (PCMW2D) split the temperature range into two sub-regions, i.e., 32-116 degrees C and 116-152 degrees C, on the basis of the spectral variation. Two-dimensional correlation spectroscopy (2DCOS) was further applied to such sub-regions in order to find the change order between varied PLLA polymorphs. The results showed that less addition of MMT (<= 3%) would lead to a well-exfoliated structure, which not only had no nucleation effect for PLLA, but also delayed the cold crystallization to a higher temperature compared with the one of pure PLLA. However, a higher addition of MMT (>= 5%) would lead to an intercalated structure, which acted as a nucleating agent and thus advanced the cold crystallization to a lower temperature. Nevertheless, the introduction of MMT cannot affect the phase transition order between the amorphous, the intermediate, the alpha'- and the alpha'-PLLAs based on 2DCOS results. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Peroxynitrite (ONOO-) is one of quite critical reactive oxygen species that acts critical roles in a number of diverse biological functions and pathological events. Notably, excessive ONOO- will lead to sorts of diseases. Thus, monitoring of endogenous ONOO- levels will be conducive to exploring the physiological activities and functions of ONOO-. Here, a simple turn-on fluorescent probe named DMX is reported using C=N bond as the ONOO- recognition site and xanthene as the fluorophore. DMX possessed a good linear dependence with ONOO- concentration (0-9 mu M), highly sensitive detection (DL = 37 nM), and excellent selectivity towards ONOO-. What is more, the biological experiments reveal that DMX is able to be utilized to track exogenous/endogenous ONOO(- )employing confocal laser scanning microscopy. Visualization of ONOO- in zebrafish was also successfully conducted, suggesting that DMX might be used to study ONOO- roles in vivo. We believe that DMX will have potential for exploring the pivotal role of ONOO- during all sorts of physiological and pathological activities. (C) 2022 Elsevier B.V. All rights reserved.
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