查看更多>>摘要：Data-driven deep learning analysis, especially for convolution neural network (CNN), has been developed and successfully applied in many domains. CNN is regarded as a black box, and the main drawback is the lack of interpretation. In this study, an interpretable CNN model was presented for infrared data analysis. An ascending stepwise linear regression (ASLR)-based approach was leveraged to extract the informative neurons in the flatten layer from the trained model. The characteristic of CNN network was employed to visualize the active variables according to the extracted neurons. Partial least squares (PLS) model was presented for comparison on the performance of extracted features and model interpretation. The CNN models yielded accuracies with extracted features of 93.27%, 97.50% and 96.65% for Tablet, meat, and juice datasets on the test set, while the PLS-DA models obtained accuracies with latent variables (LVs) of 95.19%, 95.50% and 98.17%. Both the CNN and PLS models demonstrated the stable patterns on active variables. The repeatability of CNN model and proposed strategies were verified by conducting the Monte-Carlo cross-validation. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A novel Au NPs/GeO2 nanozymes are developed as Surface-Enhanced Raman Scattering (SERS) substrates with the promising prospect for detection ChI. Herein, it is discovered that both Au NPs and GeO2 nanozymes have peroxidase-like activity, catalyzing colorless 3,3',5,5'-tetramethylbenzidine (TMB) to produce blue TMBox. Interestingly, compared with single Au NPs or GeO2 nanozymes, the Au NPs/GeO2 nanozymes show stronger peroxidase-like activity, and significantly ameliorated SERS signal of TMBox. The mentioned two enhancements are ascribed to a positive synergistic function of Au NPs/GeO2 nanozymes. Surprisingly, choline iodide (ChI) can inhibit the positive synergy in Au NPs/GeO2 nanozymes, and slow down the reaction of TMB-H2O2-Au NPs/GeO2 system. On this foundation, a new Au NPs/GeO2 SERS technique with high sensitivity, label-free detection method of choline iodide (ChI) is established, suggesting that Au NPs/GeO2 nanozymes have the potential application of water environment. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：Simple colorimetric biosensor was designed for the quantification SCN ions based on the principle of colorimetric reactions between Co2+ and SCN ions reaction using synthesized chromophore (2-(2-hydro xyphenyl)-1H-benzo[d] imidazol-5-yl)(phenyl) methanone (HBPM)/Co2+ ions conjugate which was synthesized via greener ultrawave sonication method. The structural characterization of the HBPM chromophore was confirmed by using NMR, ESI-MASS spectral techniques and the photophysical properties, sensor studies were done by using UV-Vis Spectrophotometer. Our designed HBPM/Co2+ ions conjugates have selectively detected SCN ions qualitatively and quantitatively in the presence of other human salivary interferents. As per clinical point of view, three different ranges of SCN ions from 0.1 to 2 mM for normal, 3 to 10 mM for disease, and 100-600 mu M for below normal ranges were tested successfully by our developed sensor and the LoD was calculated as 5.43 nM. The real potent application of the developed biosensor was tested in human salivary samples of both smokers and non-smokers under different ages and obtained results shown good agreement with existing clinical methods. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Lithium citrate (LC) as a common food additive and also a psychiatric drug, usually in the form of tetrahydrate can gradually lose its crystalline water and convert into LC anhydrate at temperatures higher than the room temperature. In order to quickly distinguish the tetrahydrate from the anhydrate and to study the dehydration kinetics of the LC hydrates under the influence of the temperature, terahertz time domain spectroscopy (THz-TDS) is utilized in this work. Experimental results show that the LC tetrahydrate at room temperature has an obvious absorption peak around 1.66 THz, while the LC anhydrate has no absorption peak at 0.5-3.0 THz. The absorption peak intensity of the LC tetrahydrate decreases continuously upon heating from 25 to 100 degrees C. Based on the normalized absorption peak area of the LC tetrahydrate around 1.66 THz, variation of its dehydration rate with the heating temperature is investigated and their relationship is fitted by the Arrhenius equation. The reaction activation energy of the LC tetrahydrate is derived to be 495.1 +/- 17.8 J/g with a deviation of about 3.7% from the traditional difference scanning calorimetry (DSC) measurement. These results indicate that THz-TDS can provide an efficient method to detect crystalline hydrates and can be applied to study the dehydration kinetics of crystalline hydrates with advantages of being fast, label-free and accurate. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The intensive use of antibiotics in livestock practice has a negative impact on human health and increases the antibiotic resistance. In this study feasible data interpretation algorithm along with efficient extraction protocol were combined for selective analysis of three antibiotics in milk samples. Trimethoprim, sulphamethoxazole and oxytetracycline are widely used antibiotics in veterinary pharmaceuticals. The studied antibiotics were efficiently extracted from milk samples with solidification of floating organic droplet in dispersive liquid-liquid microextraction. This extraction protocol was optimized not only to maximize extraction recoveries but also to approach the lower residue limits specified by European Union. Artificial neural networks succeeded in resolving spectral overlap between the studied drugs. The network architecture was optimized and validated for accurate and precise analysis. The proposed method outweighs the reported chromatographic methods for being simple and inexpensive and compared favorable to official methods. (c) 2021 Elsevier B.V. All rights reserved.
Basri, Katrul NadiaYazid, FarinawatiWahab, Rohaya Megat AbdulZain, Mohd Norzaliman Mohd...
6页
查看更多>>摘要：Caries is one of the non-communicable diseases that has a high prevalence trend. The current methods used to detect caries require sophisticated laboratory equipment, professional inspection, and expensive equipment such as X-ray imaging device. A non-invasive and economical method is required to substi-tute the conventional methods for the detection of caries. UV absorption spectroscopy coupled with chemometrics analysis has emerged as a good potential candidate for such an application. Data prepro-cessing methods such as mean centre, autoscale and Savitzky-Golay smoothing were implemented to enhance the signal-to-noise ratio of spectra data. Various classification algorithms namely K-nearest neighbours (KNN), logistic regression (LR) and linear discriminant analysis (LDA) were implemented to classify the severity of dental caries into International Caries Detection and Assessment System (ICDAS) scores. The performance of the prediction model was measured and comparatively analysed based on the accuracy, precision, sensitivity, and specificity. The LDA algorithm combined with the Savitzky-Golay preprocessing method had shown the best result with respect to the validation data accu-racy, precision, sensitivity and specificity, where each had values of 0.90, 1.00, 0.86 and 1.00 respectively. The area under the curve of the ROC plot computed for the LDA algorithm was 0.95, which indicated that the prediction algorithm was capable of differentiating normal and caries teeth excellently. (c) 2021 Elsevier B.V. All rights reserved.
Sofin, R. G. S.Issac, A.Al-Naabi, M. R. S.Myint, M. T. Zar...
11页
查看更多>>摘要：Carbon nanoparticles (CNPs) are getting wide attention due to their fluorescence and low level of toxicity compared to other semiconducting photoluminescent materials. CNPs show strong 'solvatochromism', and the emission mechanism is still under discussion. Florescent carbon in the form of films would tremendously increase its potential for applications. In this work, we report for the first time the fluorescent emission characteristics of carbon films formed by aggregation of CNPs. Films of carbon were grown on glass substrates by using a novel Cold Vapour Deposition System. We have performed a detailed comparative study of the emission spectra of film and CNPs (prepared using the microwave synthesis method) in various solvents. A qualitative model based on solvatochromism of CNPs is used to understand the emission pathways in the film. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The solid state photophysical properties of the 3,3'-paraphenyl bis[6,8-dimethoxy-2H-chromen-2-one] symmetrical biscoumarin material were investigated by optical spectroscopy techniques and by theoret-ical calculations. Vibrational analysis using IR absorption and Raman scattering techniques carried out together with DFT theoretical calculations have confirmed the structure of this biscoumarin. The geom-etry optimization using different functionals reveal a nonplanar equilibrium structure with a dihedral between the phenyl and the pyran rings of about 142 degrees. The UV-Visible absorption measurements and the TDDFT simulation show that this biscoumarin is characterized by a bicomponent feature resulting from 7C7C* electronic transitions and Intramolecular Charge Transfer (ICT). Solid state photoluminescence showed a bright blue-green emission at 506 nm with a large stokes shift estimated at 146 nm, and the temperature dependence study of this emission reveals two thermal evolution regimes. Finally, these good optical properties, as well as the stability of the emission, make this biscoumarin dye of potential interest for optoelectronic applications. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The potential of Raman microspectroscopy of exfoliated cells has been demonstrated for oral cancer diag-nosis. In this study, brush biopsies were collected from the buccal mucosa/tongue of healthy donors (n = 31) and from oral mucosal dysplastic lesions (n = 31 patients). Raman spectra were acquired and subjected to partial least squares-discriminant analysis (PLS-DA). The patient samples could be differen-tiated from healthy donor samples with 96% sensitivity and 95% specificity. Furthermore, PLS-DA models were developed based on cytopathological and histopathological assessment. Low and high grade dys-plasia could be discriminated with 64% sensitivity and 65% specificity based on cytopathological assess-ment, while 81% sensitivity and 86% specificity could be achieved when histopathological assessment was within six months of the brush biopsy sampling. Therefore, this explorative study has successfully demonstrated that Raman spectroscopy may have a role in monitoring patients with dysplasia and may reduce the need for multiple biopsies. (c) 2021 Elsevier B.V. All rights reserved.
NSTL
Elsevier