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81.
X. Z. Wang F. V. Buontempo A. Young D. Osborn 《SAR and QSAR in environmental research》2013,24(5):451-471
Recent literature has demonstrated the applicability of genetic programming to induction of decision trees for modelling toxicity endpoints. Compared with other decision tree induction techniques that are based upon recursive partitioning employing greedy searches to choose the best splitting attribute and value at each node that will necessarily miss regions of the search space, the genetic programming based approach can overcome the problem. However, the method still requires the discretization of the often continuous-valued toxicity endpoints prior to the tree induction. A novel extension of this method, YAdapt, is introduced in this work which models the original continuous endpoint by adaptively finding suitable ranges to describe the endpoints during the tree induction process, removing the need for discretization prior to tree induction and allowing the ordinal nature of the endpoint to be taken into account in the models built. 相似文献
82.
N. Greene P. N. Judson J. J. Langowski C. A. Marchant 《SAR and QSAR in environmental research》2013,24(2-3):299-314
Abstract It has long been recognised that the ability to predict the metabolic fate of a chemical substance and the potential toxicity of either the parent compound or its metabolites are important in novel drug design. The popularity of using computer models as an aid in this area has grown considerably in recent years. LHASA Limited has been developing knowledge-based expert systems for toxicity and metabolism prediction in collaboration with industry and regulatory authorities. These systems, DEREK, StAR and METEOR, use rules to describe the relationship between chemical structure and either toxicity in the case of DEREK and StAR, or metabolic fate in the case of METEOR. The rule refinement process for DEREK often involves assessing the predictions for a novel set of compounds and comparing them to their biological assay results as a measure of the system's performance. For example, 266 non-congeneric chemicals from the National Toxicology Program database have been processed through the DEREK mutagenicity knowledge base and the predictions compared to their Salmonella typhimurium mutagenicity data. Initially, 81 of 114 mutagens (71%) and 117 of 152 non-mutagens (77%) were correctly identified. Following further knowledge base development, the number of correctly identified mutagens has increased to 96 (84%). Further work on improving the predictive capabilities of DEREK, StAR and METEOR is in progress. 相似文献
83.
The chemical functionalization of carboxylated short multi-walled carbon nanotubes (Sh–MWCNT–COOH) by creatinine (Sh–MWCNT–amide) and later modification with aromatic aldehydes for producing 2-amino-5-arylidene-1-methyl-1H–imidazol-4(5H)-one (Sh–MWCNT–imidazols) via thermal and microwave methods have been investigated. All the products were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscope, elemental analysis, thermogravimetric analysis, derivative thermogravimetric and cellular investigations. These functionalizations have been chosen due to the active sites of CC and carbonyl groups in Sh–MWCNT–imidazols, which might be used as functional materials in the future. MTT assay was used to examine the behavior of cell proliferation after 72 h of cell culture experiments. Cellular investigations were performed for two kinds of cells, human breast and gastric cancer cells. Cellular results showed high toxicity of modified Sh–MWCNTs on the gastric cancer cells compared to breast cells. 相似文献
84.
Xia Liu Yuanbiao Zhang Haiping Shi Xiaoqing Deng 《Mathematical Methods in the Applied Sciences》2015,38(1):1-10
By using the critical point method, some new criteria are obtained for the existence and multiplicity of periodic solutions for fourth-order nonlinear functional difference equations. The proof is based on the linking theorem in combination with variational technique. Recent results in the literature are generalized and significantly improved. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
85.
本文研究一类二维非线性的广义sine-Gordon(简称SG)方程的有限差分格式.首先构造三层时间的紧致交替方向隐式差分格式,并用能量分析法证明格式具有二阶时间精度和四阶空间精度.然后应用改进的Richardson外推算法将时间精度提高到四阶.最后,数值算例证实改进后的算法在空间和时间上均达到四阶精度. 相似文献
87.
《Arabian Journal of Chemistry》2022,15(9):104022
In this study, titanium dioxide nanoparticles (NPs) were synthesized using the home microwave method, and the effect of the microwave irradiation time on the structure of NPs was investigated. In addition, the morphological effect of these NPs on the toxicity of HDMSCs cells was investigated. The crystalline structure and morphology of the NPs were analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FE-SEM); the cytotoxicity was determined by the methyl thiazolyl tetrazolium (MTT) assay. X-ray diffraction analysis revealed that all thin films had a polycrystalline nature with an anatase phase of TiO2. It was also found that the crystallite size increased with increasing microwave radiation time. The FTIR spectrum showed Ti-O-Ti properties by the peak in the range between 527 and 580 cm?1. Further, the FE-SEM images showed that the grain size increased with increasing irradiation time. The MTT assay results showed that the accumulation of NPs leads to toxicity. 相似文献
88.
Scene-based non-uniformity correction (SBNUC) algorithms are an important part of infrared image processing; however, SBNUC algorithms usually cause two defects: (1) ghosting artifacts and (2) over-correction. In this paper, we use the absolute difference based on guided image filter (AD-GF) method to validate the performance of SBNUC algorithms. We obtain a self-separation source using the improved guided image filter to process the input image, and use the self-separation source to obtain the space-high-frequency parts of the input image and the corrected image. Finally, we use the absolute difference between the two space-high-frequency parts as the evaluation result. Based on experimental results, the AD-GF method has better robustness and can validate the performance of SBNUC algorithms even if ghosting artifacts or over-correction occur. Also the AD-GF method can measure how SBNUC algorithms perform in the time domain, it’s an effective evaluation method for SBNUC algorithm. 相似文献
89.
90.
《Arabian Journal of Chemistry》2020,13(2):4134-4146
The kinetics of hydrolysis of fluvoxamine maleate (FLV) has been investigated over the pH range 1.0–12.0 at 40, 60 and 80 °C. FLV degradation follows pseudo-first-order kinetics which is consistent with the kinetics of drugs that are not readily dissolved in aqueous medium. The hydrolytic degradation rate constant (kobs) range from 0.92 (pH 6.0) to 13.8 × 10−4 min−1 (pH 1.0). The kobs represents the sum of six different degradation rate constants; the kH has been found to be higher than kOH. The FLV exhibits a typical rate- pH profile with a flat bottom over the pH range 3.0–6.0 which indicates its maximum stability at pH 6.0. Ten FLV degradants have been predicted by Zeneth software and among them four degradation products (D1, D2, D3 and D4) have been identified in degraded samples. The in-silico pharmacokinetics and toxicity of degradation products have been determined using Swiss ADME and admetSAR software. The toxicity profile reveals that D2 is both AMES toxic and carcinogenic while the rest of the products are non-AMES toxic and non-carcinogenic. All of the degradation products are high in causing fish toxicity thus their presence in pharmaceutical waste is alarming for environmental safety. 相似文献