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Flash point is a primary property used to determine the fire and explosion hazards of a liquid. New group contribution-based models were presented for estimation of the flash point of alkanes by the use of multiple linear regression (MLR) and artificial neural network (ANN). This simple linear model shows a low average relative deviation (AARD) of 2.8% for a data set including 50 (40 for training set and 10 for validation set) flash points. Furthermore, the predictive ability of the model was evaluated using LOO cross validation. The results demonstrate ANN model is clearly superior both in fitness and in prediction performance. ANN model has only the average absolute deviation of 2.9 K and the average relative deviation of 0.72%. [ABSTRACT FROM AUTHOR]

A novel quantitative structure-property relationship (QSPR) model for estimating the solution surface tension of 92 organic compounds at 20 °C was developed based on newly introduced atom-type topological indices. The data set contained non-polar and polar liquids, and saturated and unsaturated compounds. The regression analysis shows that excellent result is obtained with multiple linear regression. The predictive power of the proposed model was discussed using the leave-one-out (LOO) cross-validated (CV) method. The correlation coefficient ( R) and the leave-one-out cross-validation correlation coefficient ( R) of multiple linear regression model are 0.991 4 and 0.991 3, respectively. The new model gives the average absolute relative deviation of 1.81% for 92 substances. The result demonstrates that novel topological indices based on the equilibrium electro-negativity of atom and the relative bond length are useful model parameters for QSPR analysis of compounds. [ABSTRACT FROM AUTHOR]

A novel quantitative structure-property relationship (QSPR) model for estimating the solution surface tension of 92 organic compounds at 20 °C was developed based on newly introduced atom-type topological indices. The data set contained non-polar and polar liquids, and saturated and unsaturated compounds. The regression analysis shows that excellent result is obtained with multiple linear regression. The predictive power of the proposed model was discussed using the leave-one-out (LOO) cross-validated (CV) method. The correlation coefficient ( R) and the leave-one-out cross-validation correlation coefficient ( R) of multiple linear regression model are 0.991 4 and 0.991 3, respectively. The new model gives the average absolute relative deviation of 1.81% for 92 substances. The result demonstrates that novel topological indices based on the equilibrium electro-negativity of atom and the relative bond length are useful model parameters for QSPR analysis of compounds. [ABSTRACT FROM AUTHOR]

quantitative structure-spectrum relationship (QSSR) model was developed to simulate C nuclear magnetic resonance (NMR) spectra of carbinol carbon atoms for 55 alcohols. The proposed model, using multiple linear regression, contained four descriptors solely extracted from the molecular structure of compounds. The statistical results of the final model show that R=0.982 4 and S=0.869 8 (where R is the correlation coefficient and S is the standard deviation). To test its predictive ability, the model was further used to predict the C NMR spectra of the carbinol carbon atoms of other nine compounds which were not included in the developed model. The average relative errors are 0.94% and 1.70%, respectively, for the training set and the predictive set. The model is statistically significant and shows good stability for data variation as tested by the leave-one-out (LOO) cross-validation. The comparison with other approaches also reveals good performance of this method. [ABSTRACT FROM AUTHOR]

In order to realize the photocatalysis of TiO2 in the sunlight and directly apply it to waste water treatment, the Gd-doped TiO2 nanofibre was synthesized using two-step synthesis method as follows: Firstly, potassium carbonate, titanium dioxide and proper gadolinium oxide (dopant) were calcined in the muffle at high temperature and the doped gadolinium K2Ti4O9 fibres were obtained; secondly, the fibre was heated using glycerol as solvent until Gd-doped TiO2 nanofibres were obtained. The synthesized samples were characterized using scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The results show that Gd-doped TiO2 nanofibre heat-treated by glycerol solvent can inhibit the agglomeration, so the grain diameter of the fibre is smaller than that without heat-treated with glycerol. Meanwhile, the diameter of the fibre decreases with the increase of the heating temperature and time. 97%–98% of Gd-doped TiO2 nanofibre is anatase. The photocatalysis results showed that the photocatalysis activity of Gd-doped TiO2 nanofibre is just a little lower than that of TiO2 powder. [ABSTRACT FROM AUTHOR]

The adsorption response behaviors with n-alkanethiol self-assembled monolayers (SAMs) formed on the surface of polycrystalline gold grains have been investigated in nitrogen and oxygen saturated tetrahydrofuran (THF) solutions by using in situ quartz crystal microbalance (QCM) and atomic force microscopy (AFM). Comparing with frequency-decreased process in the nitrogen saturated solution, the response behavior shows a frequency increased process in the oxygen saturated solution, indicating that the gold corrosion is accompanied to occur in the self-assembled process of organothiol that is due to the thiol induction and oxygen oxidation. In the presence of thiol and oxygen, the corrosion effect is stronger than the adsorption effect of organothiols, such as n-dodecanethiol molecules on gold, which causes gold loss from the QCM surface, made evident from the observation of many corrosive defects or holes produced on the surface of gold grains by AFM image. Furthermore, the kinetic behavior on the corrosion rate of gold dissolved in the organothiol solution with time has been examined. The maximum quantity of gold dissolved into the thiol solution can be calculated to be approximately 8.7 × 1013 Au atoms cm-2 from the QCM data during the strong corrosion process in the oxygen saturated solution. The corresponding gold corrosion rates at fast and slow stages can be estimated to be 9.2 × 1011 and 5.4 × 1010 Au atoms cm-2 s-1, respectively. The surface coverage of SAMs increases from 3.2 to 31.2%, while the gold loss decreases from about 6 to 0.6% of an Au monolayer in the self-assembled process. [ABSTRACT FROM AUTHOR]

Comprehensive studies on the crustal structures, the anomalies of geophysical field and the seismicity in Central-South Shanxi are conducted. The research results show that there are deep tectonic background for occurring moderate earthquakes in Lingshi-Jiexiu region between Linfen and Taiyuan. From now on, the region should be attached closely. [ABSTRACT FROM AUTHOR]

Another comparative interpretation was conducted with respect to the data from 5 DSS profiles in the central and southern parts of Shanxi, leading to the conclusion that in Linxian, Linfen and Xingtai earthquake regions, through which the five profiles pass, there exist anomalous crust-mantle structure and abyssal crustal faults extending to Moho, all being regarded as the deep indications for earthquake occurrence. [ABSTRACT FROM AUTHOR]

In order to investigate the interrelations of crust and upper mantle tectonics and its velocity distribution as well as seismicity in the Yanhuai basin and its surrounding area, a nearly EW-trending Beijing-Huailai-Fengzhen wide angle reflection/refraction profile, which obliquely passes through seismic zone of Zhangjiakou-Bohai Sea and coincides with a deep reflection profile in the Yanhuai basin, was completed recently. The results show: The crust presents layered structures and its thickness gradually increases from 35.0 km in Shunyi to 42.0 km in the west end of the profile; the interior crustal interfaces appear approximately horizontal or slowly sloping down from east to west; In the Yanhuai basin, the crust presents the characteristics of higher velocities alternating with the lower ones and the low velocity bodies obviously exist in the lower part of upper crust. Moreover, there are two deep crustal fault zones which stretch to the Moho-discontinuity, are closely related with the seismicity in the Yanhuai area. [ABSTRACT FROM AUTHOR]

Background: There are two parts included in traditional imaging diagnosis teaching: theoretical lessons and experimental lessons. Most of the time, the experimental lesson is a review of the theoretical lesson. The teacher is the centre of the course and students are passive learners. Thus, in this study we included the patient problem of the imaging centre in our imaging diagnosis education. The traditional theoretical lessen was used to discuss prior knowledge, the discussion and analysis of patient problems was arranged under class, and the experimental lesson was used to synthesize and test the newly acquired information. The aim of this study is to determine whether or not integration of problem- and lecture-based learning teaching modes in imaging diagnosis education was associated with a good teaching effect. Forty-six of sixty students (76.7%) like integrated problem- and lecture-based learning teaching mode and 53 of 60 students (88.3%) think that integrated problem- and lecture-based learning teaching mode can make their ability of self-study be improved. Methods: Sixty students participated in a prospective study with a two-phase cross-over design. All of the students were divided into 2 groups of 30 each. In the first term, the first group participated in an integration of the problem- and lecture-based learning teaching mode, whereas students in the second group underwent the lecture-based learning teaching mode alone. During the second term, the teaching modes were exchanged between the two groups. A close-exam and survey were used to evaluate the teaching effect, and the data were analysed means of analysis of variance with a two-phase cross-over design and a χ2 test with a 2-tailed α of 0.05. Results: There was a statistically significant difference in the test scores between the integration of the problem- and lecture-based learning teaching mode and the lecture-based learning teaching mode alone ( P < 0.05). The integration of problem- and lecture-based learning teaching mode was well-appraised. Conclusion: Integration of the problem- and lecture-based learning teaching modes in teaching imaging diagnosis education resulted in a good teaching effect. [ABSTRACT FROM AUTHOR]