Swallowtail model for predicting the global bifurcation behavior of CO oxidation reactions

Catalytic CO oxidation on platinum group metals exhibits nonlinear phenomena such as hysteresis and bifurcation.Elucidation of the nonlinear mechanisms is important for catalyst design and control of reaction routes.Previous studies have offered initial insights into the local bifurcation behavior of CO oxidation.However,since the bifurcation behavior of CO oxidation is determined by multiple parameters such as temperature,total flux,and CO fraction,it is difficult to predict the global bifurcation behavior...     

Optical applications of quantum dots in biological system

This review presents a simple introduction on the unique properties and general synthesis of quantum dots (QDs) in which we lay emphasis on the optical applications in the biological system. The detection of biological molecules such as DNA, protein and enzyme, the cell-based analysis and in vivo animal imaging are mainly discussed.     

Photoactivity of titanium dioxide/carbon felt composites prepared with the assistance of supercritical carbon dioxide: Effects of calcination temperature and supercritical conditions

TiO2-coated carbon felt(TCF)composite catalysts have been prepared via a supercritical treatment of titanium tetraisopropoxide(TTIP)as the precursor.The physical properties of the catalysts were characterized by means of thermogravimetric and differential thermal analysis(TG–DTA),X-ray diffraction(XRD),fluorescence spectroscopy,scanning electron microscopy (SEM),and BET surface areas techniques.The photocatalytic activities of the materials were evaluated using the degradation of Congo red(CR)as a probe rea...     

Synthesis and shape memory behavior study of hyperbranched poly(urethane-tetrazole)

A novel hyperbranched poly(urethane-tetrazole)(HPUTZ) was synthesized via the A2+BB2' approach using hexadiisocyanate(HDI) and 3-(bis-(2-hydroxyethyl)) aminopropyltetrazole(HAPTZ).The molecular structure was characterized by FTIR and 1H NMR spectroscopy.The number average molecular weight was measured to be 1.05×104 g/mol with a polydispersity of 1.27 by GPC analysis.The HPUTZ was further cured by the semi-adduct(PEG-IPDI) from polyethylene glycol(PEG) reacting with isophorone diisocyanate(IPDI) to form th...     

A new procedure to enols of 2-acylmethyl-4,4-dimethyl-2-oxazolines underultrasonically dispersed potassium system

Various enols of 2-acylmethyl-4,4-dimethyl-2-oxazolines were prepared in moderate yields via ultrasonically catalyzed reactions of 2,4,4-trimethyl-2-oxazoline with arenecarboxylic esters in the presence of UDP-t-BuCl-i-Pr2NH system.     

单稳型二维格微分方程的整体解

通过解一个以-κ为初始时刻的初值问题序列,并且利用比较原理证明了单稳型二维格微分方程整体解的存在性和一些定性性质.     

采用新型La_(0.07)Sr_(0.93)SnO_3电极制备外延透明BiFe_(0.95)Mn_(0.05)O_3铁电薄膜电容器

本文使用脉冲激光沉积的方法在SrTiO3(STO)单晶衬底上采用一种新型的透明导电氧化物材料La0.07Sr0.93SnO3(LSSO)薄膜作为电极材料制备了BiFe0.95Mn0.05O3(BFMO)铁电薄膜电容器.XRD表征结果证实BF-MO/LSSO/STO外延异质结具有很好的单晶质量.光透过率的测试结果表明在500~2500nm的波长范围内,整个异质结的透光率与单纯STO衬底基片相似.在波长500nm附近BFMO出现吸收边,通过对吸收边进行(hνα)2-hν曲线拟合得到BFMO的直接光学带隙约为2.8eV.利用Pt作为上电极,我们测得了饱和的电滞回线,剩余极化Pr~60μC/cm2.     

Relative position determination of a lunar rover using high-accuracy multi-frequency same-beam VLBI

Multi-frequency same-beam VLBI means that two explorers with a small separation angle are simultaneously observed with the main beam of receiving antennas. In the same-beam VLBI, the differential phase delay between two explorers and two receiving telescopes can be obtained with a small error of several picoseconds. The differential phase delay, as the observable of the same-beam VLBI, gives the separation angular information of the two explorers in the celestial sphere. The two-dimensional relative position on the plane-of-sky can thus be precisely determined with an error of less than 1 m for a distance of 3.8×105 km far away from the earth, by using the differential phase delay obtained with the four Chinese VLBI stations. The relative position of a lunar rover on the lunar surface can be determined with an error of 10 m by using the differential phase delay data and the range data for the lander when the lunar topography near the rover and the lander can be determined with an error of 10 m.     

基于理想方案的BP神经网络土地利用规划方案评价

将神经网络方法引入土地利用规划方案的评价中,并针对没有已知的学习样本可供学习的情况,提出了一种基于"理想方案"的学习和评价方法,并以北京市平谷区王辛庄镇的土地利用规划方案评价为例,进行了实证研究.结果表明:基于理想方案的BP神经网络评价方法实现了定性分析与定量分析的有机结合,较好地保证了评价结果的客观性,是一种有效评价方法.     

交联萘沥青的组成与结构特征

萘与硫在较低温度下交联聚合，制得了可溶性好、残炭值高、软化点较低，流动性良好的交联萘沥青。结构分析发现，此沥青分子量分布较窄，主要由三到四个萘分子交联而成，推测其反应机理，估计聚合物经萘环侧位交联成环而形成长链状硫杂环类结构。