线型低密度聚乙烯三层共挤与单层流延膜的性能

对比了三种不同线型低密度聚乙烯树脂组成的三层共挤流延膜以及各单层流延膜的雾度、力学性能。实验结果表明,三层共挤流延膜的内部雾度略低于各单层流延膜的内部雾度之和,表面雾度与内外两层单层流延膜的表面雾度之和的一半相当;三层共挤流延膜的拉伸屈服强度与各单层流延膜的平均水平相当,拉伸断裂强度和断裂伸长率分别与各单层流延膜中的最大值相当;三层共挤流延膜的撕裂性能接近各单层流延膜的平均水平;三层共挤流延膜在穿刺破坏时的穿刺深度决定于各单层流延膜组成中穿刺深度最小的水平,三层共挤流延膜的整体耐穿刺强度不及各单层流延膜的平均水平;具有不对称组成的三层共挤流延膜从上、下两个表面穿刺测试时表现的耐穿刺性能不同,耐穿刺性能很可能与被穿刺表面的摩擦性能有关。

单层流驱动超临界孤立子的数值计算

用ｆＫｄＶ模式方程对单层二维表面波进行直接的数值研究。计算得出，在共振区域先锋孤立子的生成与Ｔ、Ｙ．Ｗｕ（吴耀祖）及Ｓ．Ｊ．Ｌｅｅ等人的结果相同。在共振点与超临界转向点之间，对每一个Ｆｒ数存在初始不稳定的单峰孤立子，其振幅随时间增加。当Ｆｒ数接近共振区时，初始孤立子分裂成先峰孤立子，即先峰孤立子生成是占优的。当Ｆｒ接近超临界转向点时，这类初始不稳定孤立子最终破碎。当Ｆｒ超过超临界转向点时，存在一类稳定的超临界孤立子，其振幅不随时间变化，但是它得自时间相关方程。这类孤立子位于驱动力上方，它的振幅随Ｆｒ的增加而减少．由于它不同于自由ＫｄＶ孤立子，因此本文称之为超临界驻定孤立子。

单层流先锋孤立子生成问题中的尾波列生成

根据Whitham平均方法提出了单层流先锋孤立子生成中尾波列生成的理论。尾波列的群特征是由无源项的单层流fKdV方程的演化方程组来表征。基于该演化方程组理论上求得了尾波列的群速度和尾波列生成的一个理论解。在实验室坐标中对单层流的fKdV方程进行了数值模拟。结果表明,理论和数值结果之间有很好的一致性。

挤出温度对单层流延聚丙烯膜结构与性能的影响

采用控制变量法制备出不同挤出温度下的单层流延聚丙烯(Monolayer Cast Polypropylene,MCPP)薄膜试样,探究挤出温度对薄膜光学性能、力学性能的影响,并用偏光显微镜和差示扫描量热仪分别对不同薄膜试样进行了取向结构和结晶度的表征。结果表明:随着挤出温度的升高,薄膜的横向拉伸性能、纵向拉伸性能和撕裂性能先增强后减弱,在220~230℃时性能表现优异;薄膜的取向结构和结晶度均减弱。

走向成熟的国产流延薄膜设备

流延膜是通过熔体流延骤冷生产的一种无拉伸、非定向的平挤薄膜，有单层流延和多层共挤流延两种方式。与吹膜相比，其特点是生产速度快，产量高，薄膜的透明性，光泽性、厚度均匀性等都很出色。同时，由于流延膜是平挤薄膜，其后续工序，如印刷，复合等都极为方便，因而被广泛应用于食品，医药用品，纺织品、鲜花，日用品的包装。

Anthropogenic Direct Radiative Forcing of Tropospheric Ozone and Aerosols in 1850 and 2000 Estimated with IPCC AR5 Emissions Inventories

This study estimates direct radiative forcing by tropospheric ozone and all aerosols between the years 1850 and 2000, using the new IPCC AR5 （the Intergovernmental Panel on Climate Change Fifth Assessment Report） emissions inventories and a fully coupled chemistry-aerosol general circulation model. As compared to the previous Global Emissions Inventory Activity （GEIA） data, that have been commonly used for forcing estimates since 1990, the IPCC AR5 emissions inventories report lower anthropogenic emissions of organic carbon and black carbon aerosols and higher sulfur and NOx emissions. The simulated global and annual mean burdens of sulfate, nitrate, black carbon （BC）, primary organic aerosol （POA）, secondary organic aerosol （SOA）, and ozone were 0.79, 0.35, 0.05, 0.49, 0.34, and 269 Tg, respectively, in the year 1850, and 1.90, 0.90, 0.11, 0.71, 0.32, and 377 Tg, respectively, in the year 2000. The estimated annual mean top of the atmosphere （TOA） direct radiative forcing of all anthropogenic aerosols based on the AR5 emissions inventories is -0.60 W m^-2 on a global mean basis from 1850 to 2000. However, this is -2.40 W m-2 when forcing values are averaged over eastern China （18-45°N and 95-125°E）. The value for tropospheric ozone is 0.17 W m^-1 on a global mean basis and 0.24 W m^-2 over eastern China. Forcing values indicate that the climatic effect of aerosols over eastern China is much more significant than the globally averaged effect.

Depinning Dynamics of Fluid Monolayer on a Quenched Substrate

Langevin simulations are preformed on the depinning dynamics of fluid monolayer on a quenched substrate. With increase in the strength of the substrate, we find for the first time a crossover from elastic crystal to smectic flows as well as a crossover from smectic to plastic flows above the depinning. A power-law scaling relationship can be derived between the drift velocity and the driving force for both the elastic crystal and smectic flows, but fails to be obtained for the plastic flow. The power-law exponents are found to be no larger than 1 for the elastic crystal flow and larger than 1 for the smeetic flow. The critical driving force and the averaged intensity of Bragg peaks remain invariant basically in the regime of smectic flow. A sudden increase in the critical driving force is observed within the crossover from the smeetic to plastic flows, and the averaged intensity of Bragg peaks shows sudden decreases within the crossovers both from the elastic crystal to smectic flows and from the smectic to plastic flows. The results are helpful for understanding the slip dynamics of fluids on a molecular level.

Upregulated CD133 expression in tumorigenesis of colon cancer cells

AIM: To analyze the upregulated CD133 expression in tumorigenesis of primary colon cancer cells. METHODS: Upregulated CD133 expression in tumorigenesis of colorectal cancer cell lines (Lovo, Colo205, Caco-2, HCT116 and SW620) was analyzed by flow cytometry. Human colon cancer tissue samples were stained with anti-human CD133. SW620 cells were sorted according to the CD133 expression level measured by fluorescence-activated cell sorting. Spheroids of colorectal cancer cells were cultured with the hanging drop. Expression of CD133 and Lgr5 in spheroids of colorectal cancer cells and monolayer culture was detected by RT-qPCR. Spheroids of colorectal cancer cells were analyzed using anti-human CD133 with immunohistochemical staining. RESULTS: CD133 antigen was expressed in colorectal cancer cell lines (Lovo, Colo205, Caco-2, HCT116 and SW620) as well as in primary and metastatic human colon cancer tissues. However, the CD133 was differently expressed in these cell lines and tissues. The expression levels of CD133 and Lgr5 were significantly higher in spheroids of parental, CD133hi and CD133-cells than in their monolayer culture at the mRNA level (P < 0.05). Immunohistochemical staining of spheroids of CD133-cells showed that CD133 was highly expressed in colorectal cancer cell lines. CONCLUSION: Upregulated CD133 expression plays a role in tumorigenesis colorectal cancer cells, which may promote the expression of other critical genes that can drive tumorigenesis.

Comparison of percutaneous transhepatic portal vein embolization and unilateral portal vein ligation

AIM： To compare the effect of percutaneous transhepatic portal vein embolization （PTPE） and unilateral portal vein ligation （PVL） on hepatic hemodynamics and right hepatic lobe （RHL） atrophy.METHODS： Between March 2005 and March 2009, 13 cases were selected for PTPE （n = 9） and PVL （n = 4） in the RHL. The PTPE group included hilar bile duct carcinoma （n = 2）, intrahepatic cholangiocarcinoma （n = 2）, hepatocellular carcinoma （n = 2） and liver metastasis （n = 3）. The PVL group included hepatocellular carcinoma （n = 2） and liver metastasis （n = 2）. In addition, observation of postoperative hepatic hemodynamics obtained from computed tomography and Doppler ultrasonography was compared between the two groups.RESULTS： Mean ages in the two groups were 58.9 ± 2.9 years （PVL group） vs 69.7 ±3.2 years （PTPE group）, which was a significant difference （P = 0.0002）. Among the indicators of liver function, including serum albumin, serum bilirubin, aspartate aminotransferase, alanine aminotransferase, platelets and indocyanine green retention rate at 15 min, no significant differ- ences were observed between the two groups. Preop-erative RHL volumes in the PTPE and PVL groups were estimated to be 804.9 ±181.1 mL and 813.3 4±129.7 mL, respectively, with volume rates of 68.9% ± 2.8% and 69.2% ±4.2%, respectively. There were no significant differences in RHL volumes （P = 0.83） and RHL volume rates （P = 0.94）, respectively. At 1 mo after PTPE or PVL, postoperative RHL volumes in the PTPE and PVL groups were estimated to be 638.4±153.6 mL and 749.8 ± 121.9 mL, respectively, with no significant difference （P = 0.14）. Postoperative RHL volume rates in the PTPE and PVL groups were estimated to be 54.6% ± 4.2% and 63.7% ± 3.9%, respectively, which was a significant difference （P = 0.0056）. At 1 mo after the operation, the liver volume atrophy rate was 14.3% ± 2.3% in the PTPE group and 5.4%± 1.6% in the PVL group, which was a significant difference （P = 0.0061）.CONCLUSION： PTPE is a more effective procedure than PVL because PTPE is able to occlude completely the portal branch throughout the right peripheral vein.

Closely packed nanoparticle monolayer as a strain gauge fabricated by convective assembly at a confined angle

The reliability and sensitivity of a strain gauge made from a nanoparticle monolayer intrinsically depend on electron tunneling between the adjacent nanoparticles, so that creating nanoscale interstitials with uniform distribution and tuning the interparticle separation reversibly during cyclic mechanical stress are two vital issues for performance enhancement. In this work, one assembly technique is initialized to fabricate parallel nanoparticle strips by precisely tailoring the contact angle of a gold colloid on a substrate. The assembly of a nanoparticle monolayer with a close-packed pattern can be simultaneously switched on and off by independently varying the contact angle across a threshold value of 4.2~. This nanoparticle strip shows a reversible and reliable electrical response even if a mechanical strain as small as 0.027% is periodically supplied, implying well-controlled electron tunneling between the adjacent nanoparticles.

Polyfluorenes containing pyrazine units:Synthesis,photophysics and electroluminescence

A series of conjugated copolymers of 9,9-dioctylfluorene and symmetrical pyrazine unit (BY) were synthesized by Suzuki copolymerization and were used as novel light-emitting materials in PLEDs.Efficient energy transfer was observed in both thin film and solution.Compared with the lowest occupied molecular orbital (LUMO) energy level of the polyfluorenes homopolymer (PFO),the lower LUMO energy levels of copolymers indicated that the introduction of the BY unit would be benefit to electron injection.The turn-on voltages of their single-layer electroluminescent (EL) devices (ITO/PEDOT/polymer/LiF/Al) were at 6.1-4.0 V,which were much lower than that of PFO (7.0 V).The maximum brightness,current efficiency,and external quantum efficiency of all PFBY copolymers were higher than those of the PFO homopolymer.The single-layer device of PFBY5 was the best one in the copolymers,with a maximum brightness of 485 cd/m2,a current efficiency of 0.29 cd/A,and an external quantum efficiency of 0.10%.The introduction of PVK and TPBI for the multilayer device of PFBY5 increased the device efficiencies,which showed a maximum brightness of 3012 cd/m2,a maximum current efficiency of 1.81 cd/A,and an external quantum efficiency of 0.66%.

Efficient quantum dot light-emitting diodes with ultra-homogeneous and highly ordered quantum dot monolayer

Regarding conventional quantum dot lightemitting diodes(QLEDs)fabricated by using the spin-coating(SC)technique,voids and interstitial spaces are inevitable due to unordered quantum dots(QDs)stacking,generating device leakage current under an external bias.In the present study,we fabricated an ultra-homogeneous and highly ordered QD monolayer by adopting the Langmuir-Blodgett(LB)technique.The QD monolayer was transferred as a emissive layer with a horizontal lifting(HL)method to a red QLED,which exhibited high performance with an external quantum efficiency(EQE)of 19.0% and lifetime(T_(95)@100 cd m^(-2))of13,324 h.When compared with the SC-based device,the EQE and lifetime were improved by 15% and 183% due to the compact and ordered QD monolayer that lowered the leakage current.Moreover,white QLEDs with stacked QD monolayers could be obtained at a low voltage of 4 V because LB technique is an organic-solvent-free approach avoiding interlayer mixing and controlling the QD layer thickness precisely.In addition,we successfully fabricated an ultra-homogeneous large-area QD monolayer on a rectangular substrate with a size of 9 cm×5 cm,indicating the promising size scalability of the LB-HL strategy.

MoSe2 porous microspheres comprising monolayer flakes with high electrocatalytic activity

A facile colloidal route to synthesize MoSe2 porous microspheres with diameters of 400-600 nm made up of MoSe2 monolayer flakes （-0.7 nm in thickness） is reported. The solvents trioctylamine （TOA） and oleylamine （OAM） are found to play important roles in the formation of MoSe2 microspheres, whereby TOA determines the three-dimensional （3D） microspherical morphology and OAM directs the formation of MoSes monolayer flakes. The robust 3D MoSe2 microspheres exhibit remarkable activity and durability for the electrocatalytic hydrogen evolution reaction （HER） in acid, maintaining a small onset overpotential of -77 mV and keeping a small overpotential of 100 mV for a current density of 5 mA/cm2 after 1,000 cycles. In addition, similar 3D WSe2 microspheres can also be prepared by using this method. We expect this facile colloidal route could further be expanded to synthesize other porous structures which will find applications in fields such as in energy storage, catalysis, and sensing.

Green phosphorescent organic light-emitting devices based on different electron transport layers combining with fluorescent sub-monolayer

We report a small molecule host of 4,4(-N,N)-dicarbazole-biphenyl(CBP) doped with 8% tris(2-phenylpyridine) iridium(Irppy3) for use in efficient green phosphorescent organic light-emitting devices(PHOLEDs) combined with different electron transport layers of Alq and BAlq. The PHOLEDs exhibit maximum current efficiency and power efficiency of 19.8 cd/A and 6.21 lm/W, respectively. The high performance of such PHOLEDs is attributed to the better electron mobile ability of BAlq and sub-monolayer quinacridone(QAD) as carrier trapping layer and equal charge carrier mobilities of hole and electron to form the broad carrier recombination zone in the emitting layer, which can 1reduce the triplet-triplet annihilation and improve the efficiency of the device.

The relations between density of FACs in the Plasma Sheet Boundary Layers and Kp index

We have studied 172 field-aligned currents （FACs） cases observed by the ClusterlI satellites when they crossed the plasma sheet boundary layer （PSBL） in the magnetotail from July to October 2001. We mainly analyzed the relationship between the characteristic of FACs at the PSBL in magnetotail and the Kp index. The main results indicated the followings： 1） In the different geomagnetic activity levels, the relative occurrence of FACs in PSBL increased monotonically with geomagnetic activity. 2） The density of FACs in PSBL increased monotonically with Kp index. In the storm main phase, the density of FACs increased dramatically, the maximum FACs approximately equaled 19.05 nA m-2 while Kp equaled 5.3） The variation of FACs density in PSBL was consistent with the variation of the Kp index. However, when AE〈800 nT, FACs density in PSBL increased with increasing AE, and when AE〉800 nT, it decreased with increasing AE. Therefore, our results suggested that the FACs density in PSBL had a closer correlation with Kp index.

Transports of air particulate matters in the atmospheric boundary layer-numerical studies using Eulerian and Lagrangian methods

Transports of air particulate matters(PM) from face sources in the atmospheric boundary layer(ABL) are investigated by the Eulerian single fluid model and the Lagrangian trajectory method,respectively.Large eddy simulation is used to simulate the fluid phase for high accuracy in both two approaches.The mean and fluctuating PM concentrations,as well as instantaneous PM distributions at different downstream and height positions,are presented.Higher mean and fluctuating particle concentrations are predicted by the Eulerian approach than the Lagrangian one.For the Lagrangian method,PM distributions cluster near the ground-wall because of the preferential dispersion of inertial particles by turbulence structures in the ABL,while it cannot be obtained by the Eulerian single fluid method,because the two-phase velocity differences are neglected in the Eulerian method.