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211.
In this paper, we analyze the energetic and conformational preferences involved in the chiral discrimination of ibuprofen (Ibu) isomers by beta-cyclodextrin (β-CD) when forming inclusion complexes in water. This study was performed by means of atomistic molecular mechanics simulations upon four different penetration modes of the guest, and a structural 2D NMR experiment. The trajectories of these simulations were treated with the MM/GBSA method in order to obtain the relative weights of the different free energy components. The resulting values of the free energy of binding and other geometrical features indicate that this chiral selectivity is influenced by a preferred penetration mode involving the S-(+)-Ibu isomer. The calculated ΔΔG of binding is in good agreement with published experiments. 相似文献
212.
Jin Zhang Hong Jiang Pengya Gao Yuan Wu Hui Sun Ying Huang Xuefang Xu 《Journal of Raman spectroscopy : JRS》2021,52(11):1820-1829
Rapid and accurate identification of Clostridium botulinum is of great importance because it has been considered as an emerging food-borne pathogen and potential zoonotic agent. Raman spectroscopy can differentiate bacteria based on Raman scattering spectral patterns of whole cells in a fast, reagentless, and easy-to-use manner. This study demonstrates that confocal Raman microspectroscopy (CRM) combined with chemometrics can serve as a fast, reliable, and nondestructive method for detection and identification of C. botulinum at both species and serotypes level without any laborious pre-treatments. Three significant bacillus pathogens including C. botulinum, C. perfringens, and C. difficile were investigated with CRM. Additionally, two main C. botulinum strains causing botulism, C. botulinum type A, and C. botulinum type B were examined with CRM. Principal component analysis (PCA) was performed to differentiate the three species. PCA and linear discrimination analysis (LDA) were used for serotyping C. botulism strains. Four common and important preprocessing methods including Savitzky–Golay algorithm smoothing (SG), standard normal variate (SNV), multivariate scatter correction (MSC), and Savitzky–Golay algorithm 1st Derivative (SG 1st Der) were applied to improve the accuracy of identification and explore the impact of various single preprocessing methods on the model. The results proved that CRM coupled with chemometrics can be utilized for fast, reliable, and nondestructive identification of clostridia and serotypes of C. botulinum strains. This study proves for the first time that the CRM combined with chemometrics methods can be used as a potential means to detect and identify C. botulinum. 相似文献
213.
Gang Li Hong-Dong Ma Rong-Yue Liu Meng-Di Shen Ke-Xin Zhang 《Entropy (Basel, Switzerland)》2021,23(5)
Background: the credit scoring model is an effective tool for banks and other financial institutions to distinguish potential default borrowers. The credit scoring model represented by machine learning methods such as deep learning performs well in terms of the accuracy of default discrimination, but the model itself also has many shortcomings such as many hyperparameters and large dependence on big data. There is still a lot of room to improve its interpretability and robustness. Methods: the deep forest or multi-Grained Cascade Forest (gcForest) is a decision tree depth model based on the random forest algorithm. Using multidimensional scanning and cascading processing, gcForest can effectively identify and process high-dimensional feature information. At the same time, gcForest has fewer hyperparameters and has strong robustness. So, this paper constructs a two-stage hybrid default discrimination model based on multiple feature selection methods and gcForest algorithm, and at the same time, it optimizes the parameters for the lowest type II error as the first principle, and the highest AUC and accuracy as the second and third principles. GcForest can not only reflect the advantages of traditional statistical models in terms of interpretability and robustness but also take into account the advantages of deep learning models in terms of accuracy. Results: the validity of the hybrid default discrimination model is verified by three real open credit data sets of Australian, Japanese, and German in the UCI database. Conclusions: the performance of the gcForest is better than the current popular single classifiers such as ANN, and the common ensemble classifiers such as LightGBM, and CNNs in type II error, AUC, and accuracy. Besides, in comparison with other similar research results, the robustness and effectiveness of this model are further verified. 相似文献
214.
Tianheng Chen Hao Yu Xianfei Wen Caleb Redding Tibor Jacob Hajagos Hongxiang Zhao Jason P. Hayward Chuluo Yang Qibing Pei 《Advanced Optical Materials》2021,9(7):2001975
Pulse shape discrimination (PSD)-capable plastic scintillator is in demand for the detection of high-energy neutrons in the presence of gamma radiation background. Conventional PSD plastics are based on delayed fluorescent dye via triplet–triplet annihilation of a fluorescent dye additive, which is inefficient to harvest the energy of triplet excitons. In recent years, thermally activated delayed fluorescence (TADF) emitters have gained substantial success in organic light-emitting diodes due to their efficient utilization of the energy of triplet excitons and thereby achieving theoretical unity internal quantum efficiencies. Herein, a highly efficient TADF dye 9-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-methylphenyl)-3,6-dioctyl-9H-carbazole is reported for the PSD application. This TADF dye may be loaded up to 30 wt% in polyvinyltoluene matrix and still retains high optical transparency. High scintillation light yield and PSD figures of merit are obtained from the TADF plastic. With the introduction of a secondary dye to further increase the utilization efficiency of the excitation energy, the light yield is increased to 6948 photons MeV−1. The measured alpha/gamma PSD figure of merit is 1.12 at the energy threshold of 100 keVee and neutron/gamma PSD figure of merit is 1.32 at the threshold of 1000 keVee. 相似文献
215.
Photodynamic therapy (PDT) represents an effective treatment to cure cancer. The targeting ability of the photosensitizer is of utmost importance. Photosensitizers that discriminate cancer cells can avoid the killing of normal cells and improve PDT efficacy. However, the design and synthesis of photosensitizers conjugated with a recognition unit of cancer cell markers is complex and may not effectively target cancer. Considering that the total RNA content in cancer cells is commonly higher than in normal cells, this study has developed the photosensitizer QICY with RNA-targeting abilities for the discrimination of cancer cells. QICY was specifically located in cancer cells rather than normal cells due to their stronger electrostatic interactions with RNA, thereby further improving the PDT effects on the cancer cells. After intravenous injection into mice bearing a xenograft tumor, QICY accumulated into the tumor location through the enhanced permeability and retention effect, automatically targeted cancer cells under the control of RNA, and inhibited tumor growth under 630 nm laser irradiation without obvious side effects. This intelligent photosensitizer with RNA-targeting ability not only simplifies the design and synthesis of cancer-cell-targeting photosensitizers but also paves the way for the further development of highly efficient PDTs. 相似文献
216.
Danielle Bury Guy Faust Maria Paraskevaidi Katherine M. Ashton Timothy P. Dawson 《Analytical letters》2019,52(4):575-587
Metastatic brain tumors represent a significant proportion of tumors identified intraoperatively. A rapid diagnostic method, circumventing the need for histopathology studies, could prove clinically useful. As many spectroscopic studies have shown ability to differentitate between different tumor types, this technique was evaluated for use within metastatic brain tumors. Spectrochemical approaches [Raman and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) spectroscopy] were applied to determine how readily they may identify the primary site for the metastatic tumor. Metastases were from primary adenocarcinomas of lung (n?=?7) and colorectum (n?=?7), and for comparison, metastatic melanoma (n?=?7). The objective was to determine if Raman or ATR-FTIR spectroscopy could delineate the origin of the primary tumor. The results demonstrate that there are marked similarities between the two adenocarcinoma groups and whilst Raman and ATR-FTIR can distinguish the three groups with limited success, classification accuracy is greatly improved when combining the adenocarcinoma groups. The use of such techniques in the clinical setting is more likely to be found intraoperatively, determining the presence of a tumor and suggesting the tumor class; however, traditional histopathology would still be needed to identify the primary origin of the tumor. 相似文献
217.
Tatiana V. Shishkanova Gabriela Broncov Annemarie Sklov Vadym Prokopec Martin lupek Vladimír Krl 《Electroanalysis》2019,31(10):2024-2031
The flavor aspect of pharmaceutical formulations is very important in terms of their acceptability for the patient. This work is aimed at using of a novel promising type of electronic tongue (ET), consisting of a potentiometric sensor array, for the discrimination and assessment the taste of commercial pharmaceuticals based on ibuprofen (Ibuflam 4 %). The sensor array was formed by six ion‐selective membranes (ISMs) based on both specific and non‐specific active components. Analysis of potentiometric signal outputs including statistical data processing utilizing the principal component analysis (PCA) method allowed evaluating the role of individual active components of the ISMs in the sense of taste control of the pharmaceutical preparation Ibuflam 4 % before and after flavoring. The sensing array can be used to identify differences in flavor within individual batches from the same producer, since ISMs provide a different response to all components present in the analyzed pharmaceutical. The ET contains ISMs which are able to recognize the bitter taste in the framework of the batches of ibuprofen based pharmaceuticals. To recognize bitter taste, it was essential to include ISMs, providing a response to a particular type of taste, namely, specific and non‐specific ISMs. The experimental findings show that taste‐sensing potentiometric sensor system can be a good alternative to the human panel and is able to detect the slight changes in taste. 相似文献
218.
《Journal of mass spectrometry : JMS》2018,53(8):693-699
In this work, the use of MALDI traveling wave ion mobility spectrometry‐mass spectrometry (MALDI‐TWIMS‐MS) for stereoselective structural analysis of direct cleavage and identification of 2‐substituted piperidines obtained through solid‐phase asymmetric synthesis by using heterogeneous 8‐phenylmenthyl‐based chiral auxiliary resins. A strategy for gas‐phase chiral and structural characterization of small molecular weight molecules by using MALDI‐IMS‐MS technique is discussed. Because both MALDI and IMS do not directly offer chiral resolution, an easy methodology by adding a chiral phase is described to carry out in situ online ion/molecule complexation with different chiral analytes inside the mass spectrometer. Piperidine enantiomers were resolved, and separation obtained shows dependence of surface areas. To corroborate this assumption and elucidate the separation mechanism to accomplish an analytical technique by which fast determination of the chirality of molecules may be determined for a wide range organic compound applications, it was performed DFT calculations to determine the cross‐sectional areas of proton‐bound dimer complexes. Drift times are affected by cross‐sectional areas, correlating bigger times with bigger molecular volumes during the ion mobility experiments of proton‐bound dimer complexes. 相似文献
219.
220.