In this paper we consider nonparametric (auto-)regressive models with conditional variance function. Based on polynomial spline estimation, we construct the estimators of conditional mean function and conditional variance function. Consistency of these estimators is proved under the
-mixing condition. Meanwhile, uniform and global rates of convergence of these estimators are established, and global rates of convergence can attain to the optimal ones. Moreover, a method for selecting knot number is developed based on Bayes Information Criterion. The methodology is illustrated by a simulation study and is applied to CNY/USD middle exchange rate.
The academic level and scientific reputation is the most important merit of a research university. Publication of the scientific achievement in the world leading scientific journals is the key to asses a university's overall performance. Peking University is a leading university among the Chinese research universities, and the number of papers published in Science Citation Index (SCI) indexed journals has been on the top of the national list. In this paper, based on our long-term experience and practice in scientific management, we use scientometrics and informetrics method to analyze the academic performance of the researchers, departments and schools of Peking University, mainly using the citations of publications. Highly cited papers are specially important to the reputation of our university. We compare those data with some selected world well-known universities, hence, some important information can be deduced for the policy decision of the university. The results presented here is not only an academic survey, but also a guideline for the future strategic development of Peking University.
Authors:Dezhu Wu, Zheng Zhang, Baoling Chen, and Ginfu Li
The synthesis of [3H]-higenamine by a four steps reaction, namely condensation, cyclization, catalytic tritiation and demethoxylation is described. The acidulated product was purified by thin layer chromatography and the final component has a high specific activity and radiochemical purity.
Authors:Lihua Gu, Shansong Zheng, Tao Wu, Guixin Chou, and Zhengtao Wang
A simple and accurate high-performance thin-layer chromatography (HPTLC)-bioautographic method was developed for the quantitative analysis of magnolol and honokiol in the herbal medicine Magnoliae officinalis Cortex. The samples were separated on a silica gel HPTLC plate with a mixture solution of toluene-methanol (10:1, v/v) as the mobile phase. Spots were visualized by dipping in 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*) reagent and measured at a wavelength of 550 nm in a reflection mode, scanning after derivatization for 40 min. The method had excellent linearity (r2 = 0.9939 for magnolol and r2 = 0.9989 for honokiol, respectively) in the concentration range of 0.16–0.97 mg spot−1 for both analytes. The recoveries were 94.5–105.9% for magnolol and 86.6–103.4% for honokiol, respectively. The established HPTLC-bioautographic method was evaluated comprehensively in quantitative and antioxidant activity analysis of magnolol and honokiol in Magnoliae officinalis Cortex and various plants.
The thermal behavior of kaolinite–dimethylsulfoxide intercalation complex was investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC) analysis, X-ray diffraction (XRD) analysis, and Fourier-transform infrared (FT-IR) spectroscopic analysis. The samples gradually heated up to different temperatures were studied by XRD and FT-IR. The kaolinite–dimethylsulfoxide intercalation complex is stable below 130 °C. With the rise in the temperature, the relative intensity of the 1.124-nm peak gradually decreased and disappeared at 200 °C, however, the intensity of the 0.714 nm peak increased in the XRD patterns. In the infrared spectra, the appearance of methyl bands at 3018, 2934, 1428, and 1318 cm−1 indicates the presence of intercalated dimethylsulfoxide, the intensities of these bands decreased with the temperature rising and remained until around 175 °C, which agree with the XRD and TG–DSC data.
Authors:Jun Yuan, Wei Yue, Cheng Su, Zheng Wu, Zheng Ma, Yun Pan, Nan Ma, Zhi Hu, Fei Shi, Zheng Yu, and Yi Wu
This research intends to investigate the patent activity on water pollution and treatment in China (1985–2007), and then compares
the results with patents data about Triadic patents, South Korea, Brazil and India over the same periods, patents data were
collected from Derwent World Patents Index between 1985 and May 2008. For this study, 169,312 patents were chosen and examined.
Total volume of patents, technology focus, assignee sector, priority date and the comparison with other countries are analyzed.
It is found that patents on water pollution and treatment filed at China have experienced a remarkable increase and the increase
rate of patents filed at China change simultaneous with the percentage of domestic applications. However, the number of high
quality Triadic patents with priority country as China remains small. Furthermore, in addition to individual patent assignees,
both Chinese universities and enterprises also play important roles in patent activity of water pollution and treatment. In
addition, the pattern of South Korea’s development can provide short-term implications for China and the regularity in Triadic
patents’ development can provide some guidance to China’s long-term development. In contrast, the development pattern of Brazil
and India is less influential to China’s development. Furthermore, China’s technology focuses on water pollution and treatment
seem to parallel global and triadic patent trends. This research provides a comprehensive picture of China’s innovation capability
in the area of water pollution and treatment. It will help China’s local governments to improve their regional S&T capability
and will provide support the National Water Pollution Control and Treatment Project in China.
Authors:Kai Zheng Fang, Dao Bin Mu, Shi Chen, Feng Wu, and Xiao Jun Zeng
The thermal behavior of D-type Ni–MH battery during charging was investigated at a wide range of ambient temperatures in this work. The temperature measurement of the battery was conducted by using a thermal infrared imager put in a high–low temperature chamber. The ambient temperatures were controlled to −10, 0, 10, 20, 30, and 40 °C during charging. The battery was charged to SOC of 110% in the rate of 1C, 3C, and 5C. Real-time infrared thermal images of battery surface were obtained during charging, as well as temperature change curves. The maximum surface temperature of the battery at the end of charging was stimulated at a higher ambient temperature by curve fitting. It is indicated that the temperature gradient on battery surface will increase with charging rate increase, and the rate of actual temperature rise is almost unrelated to ambient temperature. The simulating result shows that the maximum surface temperature would be over 101 °C if the battery is charged in the rate of 5C under an ambient temperature of 70 °C, which may lead to a safe accident.
Authors:Qiangqiang Ren, Changsui Zhao, Xin Wu, Cai Liang, Xiaoping Chen, Jiezhong Shen, and Zheng Wang
The catalytic effects of iron, aluminum or silicon on the formation of NOX precursors (HCN, NH3 and HNCO) and HCl during wheat straw pyrolysis were studied using a thermogravimetric analyzer (TG) coupled with a Fourier
transform infrared (FTIR) spectrometer in argon atmosphere. The results show that the presence of iron, aluminum or silicon
decreases conversion of straw-N into NH3 with the sequence of Fe > Si > Al. The iron or silicon addition suppresses N-conversion into HCN and HNCO, and the aluminum
addition has no notable influence on HCN emission during pyrolysis. The share of N-conversion to NH3 and HCN increases, but that to HNCO and NO decreases a little in the presence of added iron, aluminum or silicon. The addition
of SiO2 results in the highest HCl removal efficiency.
Authors:Haiya Wu, Mengrou Lu, Jiamin He, Miaoling Huang, Aote Zheng, Meiling Zhang, Congcong Wen, and Jufen Ye
In this study, a precise, rapid, and accurate ultra-performance liquid chromatography–tandem mass spectrometer (UPLC–MS/MS) method for the quantitation of O-demethyl nuciferine in mouse blood was developed, and pharmacokinetics of O-demethyl nuciferine was studied for the first time after sublingual injection and gavage. The study was performed with an UPLC ethylene bridged hybrid (UPLC BEH) (2.1 mm × 50 mm, 1.7 μm) column at 30 °C, using diazepam as the internal standard (IS). The mobile phase consisted of acetonitrile–10 mmol/L ammonium acetate (containing 0.1% formic acid), with a flow rate of 0.4 mL/min for 4 min run time. Multiple reaction monitoring (MRM) modes of m/z 282.1→219.0 for O-demethyl nuciferine and m/z 296.2→265.1 for IS were utilized to conduct quantitative analysis. Protein in mouse blood was directly precipitated with acetonitrile for sample preparation. The linear range was 1–500 ng/mL with r > 0.995, and the lower limits of quantification (LLOQ) was 1 ng/mL. The intra- and inter-day precision of O-demethyl nuciferine in mouse blood were RSD < 14% and RSD < 15%, respectively.r The accuracy ranged from 89.0% to 110.7%, with a recovery higher than 88.9%, while the matrix effect was between 103.1% and 108.7%. We further applied this UPLC–MS/MS method to the pharmacokinetic study on O-demethyl nuciferine after sublingual injection and gavage and determined the bioavailability to be 6.4%.