KdV方程和Kupersmidt方程的递推求解公式

根据Ｐａｉｎｌｅｖｅ分析的已知结果,给出了ＫｄＶ方程和Ｋｕｐｅｒｓｃｈｍｉｄｔ方程的新的递推求解公式。     

反相高效液相色谱法测定植物组织培养基中的外源激素

建立了高效液相色谱-光电二极管阵列检测器测定植物组织培养基中6种外源激素的分析方法。采用Waters公司μBondaPak C18柱(3.9 mm×300 mm, 10 μm),用140 mmol/L乙酸钠-三乙胺缓冲液(pH 4.95)和乙腈作流动相,以75:25的比例等度洗脱,柱温37 ℃,流速1.0 mL/min,在波长285 nm下检测。在9 min内6种激素均达到基线分离,其进样量在4~200 ng之间具有良好的相关性(r2>0.9995)。培养基中的激素在减压烘干后用甲醇提取,各种激素的回收率均在85%以上。该方法可以用于植物组织培养基中外源激素的分析检测,或对培养基中未知激素的比例和种类进行分析测定。     

Electromagnetohydrodynamic flows and mass transport in curved rectangular microchannels

Curved microchannels are often encountered in lab-on-chip systems because the effective axial channel lengths of such channels are often larger than those of straight microchannels for a given per unit chip length. In this paper, the effective diffusivity of a neutral solute in an oscillating electromagnetohydrodynamic(EMHD)flow through a curved rectangular microchannel is investigated theoretically. The flow is assumed as a creeping flow due to the extremely low Reynolds number in such microflow systems. Through the theoretical analysis, we find that the effective diffusivity primarily depends on five dimensionless parameters, i.e., the curvature ratio of the curved channel, the Schmidt number, the tidal displacement, the angular Reynolds number, and the dimensionless electric field strength parameter. Based on the obtained results, we can precisely control the mass transfer characteristics of the EMHD flow in a curved rectangular microchannel by appropriately altering the corresponding parameter values.     

新型双吲哚马来酰亚胺衍生物的合成

以1-(3-氧代四氢吡喃丙基)-吲哚-3-乙醛酸甲酯(5)和吲哚-3-乙酰胺(6)为原料,在催化剂叔丁醇钾的四氢呋喃溶液存在下发生偶合反应,经浓盐酸处理得脱保护的中间体7,再经甲磺酰化反应、氨解反应得到4种新的具有不同氨烷基侧链的双吲哚马来酰亚胺衍生物9a,9b,9d,9e.目标产物结构通过1H NMR,13C NMR,MS和HRMS确证.     

A new droplet breakup phenomenon in electrokinetic flow through a microchannel constriction

A completely new droplet breakup phenomenon is reported for droplets passing through a constriction in an electrokinetic flow. The breakup occurs during the droplet shape recovery process past the constriction throat by the interplay of the dielectrophoretic stress release and the interface energy for droplets with smaller permittivity than that of the ambient fluid. There are conditions for constriction ratios and droplet size that the droplet breakup occurs. The numerical predictions provided here require experimental verification, and then can give rise to a novel microfluidic device design with novel droplet manipulations.     

云滴谱分布对FY-4A/AGRI水云光学厚度与有效粒子半径反演的影响

为了定量评估对数正态谱分布假设对水云光学厚度(COT)与有效粒子半径(Re)反演的影响，利用欧洲中期数值天气预报中心建立的RTTOV(Radiative Transfer for TIROS Operational Vertical Sounder)模式，对比模拟了基于对数正态谱和修正Gamma谱两种云滴谱分布下FY-4A/AGRI(Advanced Geosynchronous Radiation Imager)的第2、5通道液态水云的反射率，分析了这两个谱分布假设条件下水云反射率随COT以及Re的变化特征。在此基础上，建立了两种谱分布条件下的COT和Re查算表，并基于2020年夏季的一个初生对流云个例，定量分析了云滴谱分布类型对云参数反演结果的影响。结果表明，在第2通道，两个云滴谱类型假设下计算的反射率仅有0.1%～2%的差异，但在第5通道，采用修正Gamma云滴谱计算的反射率比采用对数正态云滴谱计算的反射率低10%～20%。反演结果表明，采用对数正态云滴谱反演的有效粒子半径Re比采用修正Gamma云滴谱反演的Re整体偏大，前者反演的Re集中在15～35μm,而后者反演的Re集中在...     

Origin of the Ability of α‐Fe2O3 Mesopores to Activate C−H Bonds in Methane

Methane is a most abundant and inexpensive hydrocarbon feedstock for the production of chemicals and fuels. However, it is extremely difficult to directly convert methane to higher hydrocarbons because the C?H bonds in methane are the most stable C?H bonds of all hydrocarbons. The activation of the C?H bonds in methane by using an efficient and mild route remains a daunting challenge. Here, we show that the inner surface structures of the pore walls in mesoporous α‐Fe₂O₃ possess excellent catalytic performance for methane activation and convert C?H bonds into the C?O bonds in an O₂ atmosphere at 140 °C. We found that such unusual structures are mainly comprised of turbostratic ribbons and K crystal faces and have higher catalytic activity than the (110) plane. These results are without precedent in the history of catalysis chemistry and will provide a new pathway for designing and preparing highly efficient catalytic materials.     

Hydrophilic modification of microporous polysulfone membrane via surface-initiated atom transfer radical polymerization of acrylamide

Polyacrylamide (PAM) brushes were grafted from chloromethylated polysulfone (CMPSF) membrane surface by surface-initiated atom transfer radical polymerization (SI-ATRP) to improve the membrane's hydrophilic property. In order to anchor the initiator onto polysulfone (PSF) membrane surface, CMPSF was used to prepare the microporous membrane by phase-inversion process. Attachment of the PAM chains on membrane surface was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The grafted density of PAM was calculated to be 0.08 chains nm⁻². Field emission scanning electron microscopy (FESEM) and atomic force microscope (AFM) were used to characterize the surface morphology of the CMPSF membrane and modified membrane. The number-average molecular weight (M_n) of PAM linearly increased with the polymerization time, while the static water contact angle (θ) of the membrane grafted with PAM linearly decreased. This indicated the hydrophilic property of the membrane was linearly correlated with the chain length of graft polymer. Therefore linear control of PSF membrane's hydrophilic property was realized through adjusting polymerization time.     

一款C波段极窄带高温超导滤波器

设计了一款中心频率位于C波段的10阶高温超导滤波器,相对带宽达到0.1%。该滤波器的拓扑结构采用准椭圆函数型,引入了2组CQ结构,分别来改善了滤波器的带边陡度和群时延平坦度,较好解决了寄生耦合对极窄带滤波器的影响。测试结果和仿真结果基本吻合,达到了预期目标。