查看更多>>摘要：Acetamiprid poses a serious threat to human beings. In this work, the highly transparent fluorescent quantitative PCR sealing membranes (PCR-M) developed in our previous work which had attractive characteristics such as sensitivity, stability and reproducibility, and its capability of extracting analytes quickly, was used to detect acetamiprid. The detection limit of 1 nmol/L was obtained by direct detection of CN group in acetamiprid. In order to improve the selectivity and sensitivity, acetamiprid aptamer was introduced. After the interaction of aptamer with acetamiprid the SERS signal of adenine at 730 cm(-1) increased. The detection limit of indirect detection was 10(-8) mol/L. Aptamer advanced Ag-PCR-M-based Surface enhanced Raman spectroscopy (SERS) method for indirect SERS detection which significantly improves the detection sensitivity and greatly increases the range of signal response value. This will be conducive to the detection of actual samples and expand the practical application. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this study, near infrared (NIR) spectroscopy combined with chemometrics was used for the quantitative analysis of corn oil in binary to hexanary edible blend oil. Sesame oil, soybean oil, rice oil, sunflower oil and peanut oil were mixed with corn oil subsequently to form binary, ternary, quaternary, quinary and hexanary blend oil datasets. NIR spectra for the five order blend oil datasets were measured in a transmittance mode in the range of 12000-4000 cm(-1). Partial least square (PLS) was used to build models for the five datasets. Six spectral preprocessing methods and their combinations were investigated to improve the prediction performance. Furthermore, the optimal preprocessing-PLS models were further optimized by uninformative variable elimination (UVE), Monte Carlo uninformative variable elimination (MCUVE) and randomization test (RT) variable selection methods. The optimal models acquire root mean square error of prediction (RMSEP) of 1.7299, 2.2089, 2.3742, 2.5608 and 2.6858 for binary, ternary, quaternary, quinary and hexanary blend oil datasets, respectively. The determination coefficients of prediction set (R-P(2)) and residual predictive deviations (RPDs) for the five datasets are all above 0.93 and 3. Results show that the prediction accuracy is gradually decreased with the increasing of mixture order of blend oil. However, with proper spectral preprocessing and variable selection, the optimal models present good prediction accuracy even for the higher order blend oil. It demonstrates that NIR technology is feasible for determining the pure oil contents in binary to hexanary blend oil. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Wheat flour (WF) is a common ingredient in staple foods. However, the presence of intentional or unintentional adulterants makes it difficult to guarantee WF quality. Multi-grained cascade forest (gcForest) model, a non-neural network deep learning structure, fused with image-spectra features from hyperspectral imaging (HSI) was employed for detecting adulterant type (peanut, walnut, or benzoyl peroxide) and the corresponding concentration (0.03%, 0.05%, 0.1%, 0.5%, 1%, and 2%). Based on the spectra of full wavelength and effective wavelength (EW) from hyperspectral images of WF samples, the gcForest-related models exhibited high performance (lowest ACC(p) = 92.45%) and stability (lowest area under the curve = 0.9986). Furthermore, the fusion of the EW and the image features extracted by the symmetric all convolutional neural network (SACNN) was used to establish the gcForest-related models. The maximum accuracy improvement of the fusion feature model relative to the single spectral model and the image model was 2.45% and 44.37%, respectively. The results indicate that the gcForest-related model, combined with the image-spectra fusion feature of HSI, provides an effective tool for detection in food and agriculture. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Spectrophotometry is a quick and reliable method for determining the composition of a variety of complex drug mixtures. Several mathematical models are available for the resolution of complex multicomponent UV spectra. UV spectrophotometric methods have the inherent capacity to resolve the interlaced spectra of complex mixtures quickly and appropriately, particularly for quantitative determination of components of mixture where several costly tools are not available. These methods also have the benefit of lower operational costs as they are operated using lesser amounts of analytical grade solvents and generate less waste. In this review, we discussed the theoretical background of different UV spectrometric methods for quantitative analysis of drug mixtures. The main focus of this review is to describe and report applications of extended Beer's law-based multicomponent analysis and to highlight the recent developments in the simultaneous determination of drug components from their complex mixtures. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Methyl vinyl ketone is one of the major oxidation products of isoprene, and therefore, an important precursor of secondary organic aerosol. Understanding its interactions with water is relevant to gain insight into aerosol formation and improve the predictive power of atmospheric chemistry models. The molecular complex formed between methyl vinyl ketone and water has been generated in a supersonic jet and characterized using high-resolution microwave spectroscopy in combination with quantum chemistry calculations. In this study, we show that methyl vinyl ketone interacts with water forming four 1:1 isomers connected by O - H center dot center dot center dot O and C - H center dot center dot center dot O hydrogen bond interactions. Water has been found to preferentially bind to the antiperiplanar conformation of methyl vinyl ketone. Evidence of a large amplitude motion arising from the methyl internal rotation has been found in the rotational spectra of the dimer. The threefold methyl internal rotation barrier heights have been further determined and discussed for all the species. (C) 2022 The Authors. Published by Elsevier B.V.
查看更多>>摘要：Organic room temperature phosphorescence (RTP) molecules have shown promising applications in organic light emitting diodes and vivo imaging. Thus, triplet exciton dynamics in solid phase should be revealed and the molecule should possess large two photon absorption (TPA) cross sections under near-infrared excitation. The effects of halogen substitution and intermolecular interaction on RTP and TPA properties are studied at molecular level for a series of derivatives. Surrounding environment in solid phase is considered by combined quantum mechanics and molecular mechanics method. Intermolecular interactions are evaluated by the independent gradient model and calculated through the molecular force field energy decomposition method. Minimum energy crossing point, Huang-Rhys factor and reorganization energy are discussed, triplet exciton dynamics are investigated by thermal vibration correlation function method. Results indicate that the largest TPA cross sections are found for molecule in water. The halogen substitution can enlarge the proportion of (pi, pi*) and facilitate the intersystem crossing process. Restricted intramolecular rotation motions of dihedral angle in low frequency regions are found for Br-Np-Cz-BF2 in solid phase. While enhanced vibrations of bond length and bond angle in high frequency regions are detected for I-Np-Cz-BF2. Effects of halogen substitution and intermolecular interaction on triplet exciton dynamics are highlighted. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this study, a surface enhanced Raman scattering (SERS) sensor based on Au@Ag NPs solid-phase substrate combined with chemometrics was constructed for the discrimination of three pathogenic bacteria (Staphylococcus aureus, Escherichia coli and Listeria monocytogenes). The Au@Ag NPs were synthesized and self-assembled on filter paper using the dip-coating method. The good absorbency of the filter paper immobilized the bacteria on the substrate, increased the interaction between the bacteria and the substrate, and enhanced the SERS signal of the bacteria. The main peaks of the bacterial spectra were close to each other, but the relative intensities of the vibrational peaks were significantly different, and each strain exhibited unique Raman peaks. The combination of partial least squared discriminant analysis (PLS-DA) method with bacterial SERS allowed the effective identification of the three bacteria. Moreover, the method was applied for the quantitative detection of Staphylococcus aureus with a minimum detection concentration of 10(4) cfu/mL. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Photodynamic therapy (PDT) has been successfully applied in clinical treatment several years. However, after finished treatment process the residual photosensitizer will spread throughout body, which forces patients stay in the dark room to avoid exposure in sunlight several weeks. Therefore, develop degradable photosensitizer could effectively eliminate this inconvenience. In the past, researchers have developed degradable photosensitizers based on supramolecular structure. In this study, we achieved the same effect in small molecule level. Three thiocarbonyl photosensitizers (PS) have high photogenerated O-1(2) quantum yield and can be photodegraded by laser irradiation within 15 min. And due to its high phototoxicity and low toxicity, thiocarbonyl PS still maintains its high phototoxicity. Especially, mitochondrial targeting PS 1a has better properties than many BODIPY or cyanine heavy-atom-free photosensitizers. It only needs 1 mu M to reduce HeLa cell activity to 30%. Finally the thiocarbonyl PS provided a convenient way to solve the PS residue problem without sacrificing PDT efficiency. (C) 2021 Elsevier B.V. All rights reserved.
Alminshid, Alaa H.Alalwan, Hayder A.Abdulghani, Hadeel A.Mohammed, Malik M....
5页
查看更多>>摘要：A simple, rapid, accurate, and sensitive UV-Visible spectrophotometric method has been developed to estimate ephedrine hydrochloride (Eph) in pharmaceutical drugs. This method is based on preparing chelate complex through the reaction between Eph and cobalt ion (Co (II)). Ephedrine identification is done as an Eph - Co (II) complex after extraction by chloroform at lambda max 389 nm. In this work, the optimum operation conditions such as pH, buffer volume, Co ion concentration, time of reaction and extraction, temperature, and water to organic volume ratio were determined. The linearity range of Eph has observed in the range between 1 and 80 ppm, at a wavelength of 387 nm with molar absorptivity range between 3.1867 x 103 to 1.6941 x 103(L.mol(-1).cm(-1)) and metal to legend ratio of two. The results obtaind from this study are as follow: relative standard deviation (RSD) percentage is 0.303%, detection limit (D.L) = 0.94 ppm, Sandel's sensitivity (S) = 0.0135, relative error (Erel.) % = 0.039, recovery (Rec.) %=100.039. The results confirmed no interferences of excipients on the detection of Eph, and the proposed method has successfully applied for the determination of ephedrine-HCl in pure and pharmaceutical preparations. This method has several advantages, such as its low cost, high sensitivity, and ease of operation. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：Dinitriles with a saturated hydrocarbon skeleton and a -C N group at each end can have large electric dipole moments. Their formation can be related to highly reactive radicals such as CH2CN, C2N, or CN. Thus, these saturated dinitriles are potential candidates to be observed in the interstellar medium. In this work, two members of this family, hexanedinitrile and heptanedinitrile, have been investigated through their rotational spectra. The jet-cooled broadband chirped-pulse Fourier transform microwave spectra of both molecules were measured in the 2-8 GHz frequency region. Three and six conformers of hexanedinitrile and heptanedinitrile, respectively, were detected and assigned based on the rotational and quadrupole coupling constants. (C) 2021 The Author(s). Published by Elsevier B.V.
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