管膜法聚烯烃交叉复合薄膜及其加工

一、概述用于轻包装的塑料复合薄膜从两层到七层以上,其种类多达几十种,但用于重包装的复合薄膜尚不多见。我国目前在生产和使用的重包装薄膜是由单一原料制成的单层薄膜。

管膜法单向拉伸HDPE扭结膜的生产工艺探讨

本文阐述了管膜法单向拉伸高密度聚乙烯(HDPE)扭结膜的生产工艺,分析了生产中存在的问题并提供了解决方法。

多层共挤出塑料薄膜机头的结构改进与发展

介绍了多层共挤出塑料薄膜机头——多层共挤出流延塑料薄膜机头(平膜法)和多层共挤出吹塑塑料薄膜机头(管膜法)的结构、优缺点及其最近10年来的发展状况。在平膜法机头中主要介绍了多流道式机头和喂料块式机头及供料块与多流道组合式狭缝式机头;管膜法机头中主要介绍了套管式圆柱体多层共挤出机头和叠加型圆柱体多层共挤出机头。多层共挤出薄膜机头的发展主要体现在机头结构上的不断创新以及物料的适应性不断增强和薄膜层数的不断增加等方面。

三层共挤聚烯烃热收缩膜(POF)的加工及应用

采用PP作为内外层材料,LLDPE作为中层材料,经三层共挤吹塑形成第一膜管,第一膜管经过加热后进行吹胀拉伸形成第二膜泡,制得三层共挤聚烯烃热收缩膜(POF)。研究了POF的加工工艺,并进行产品性能测试,结果均符合包装要求。具有极高的收缩率和其它类型的热收缩不能比拟的性能,应用范围特别广泛。

三层共挤聚烯烃热收缩膜(POF)的加工及应用

采用PP、LLDPE材料经双泡管膜法成型工艺生产三层共挤聚烯烃热收缩膜(POF),产品性能经测试均符合包装要求。具有其它类型的热收缩膜不能比拟的性能,应用范围特别广泛。

我国FFS袋用吹塑薄膜发展动态

介绍了生产连续性一次自动成型-开口充料-加热封口(FFS)袋用吹塑薄膜的平膜法和管膜法工艺及三层共挤膜技术,概述了国内FFS袋用吹塑薄膜的生产企业和原料使用情况。FFS袋用吹塑薄膜具有包装速度快、洁净、环保、美观等优势,随着国内合成树脂装置生产规模的扩大,FFS袋用吹塑薄膜将替代传统复合编织袋成为合成树脂包装领域的主导产品。

Preparation and Characterization of Alumina Membranes on Capillary Supports： Effect of Film-coating on Crack-free Membrane Preparation

Ceramic capillary membrane has received much attention due to its relatively high pack density and favorable mechanical strength.However,it is difficult to prepare capillary membrane on its thin support by a dip-coating method.In this study,alumina microfiltration membranes were prepared on the inner surface of alumina capillary support(outer diameter 4 mm,inner diameter 2.5 mm)by a dip-coating method.Scanning electron microscopy(SEM)observation,gas bubble pressure(GBP)method and membrane permeation test were carried out to evaluate membrane performance.Two major effects in preparation of crack-free membrane,capillary filtration and film-coating,upon the thin support were studied.The as-prepared crack-free membrane presents a narrow pore size distribution,a mean pore size of about 0.6μm and a high pure water flux of 86000 L·m -2 ·h -1 ·MPa.It is proved that the membrane thickness should be sufficiently large to overcome the defects of support surface,but it is only one of the prerequisites for the formation of crack-free membrane.Furthermore,it is demonstrated that the capillary filtration effect is greatly restricted for thin capillary support with the dip-coating method and the film-coating effect plays a crucial role in the formation of crack-free membrane.

Automated retinal blood vessels segmentation based on simplified PCNN and fast 2D-Otsu algorithm

According to the characteristics of dynamic firing in pulse coupled neural network (PCNN) and regional configuration in retinal blood vessel network, a new method combined with simplified PCNN and fast 2D-Otsu algorithm was proposed for automated retinal blood vessels segmentation. Firstly, 2D Gaussian matched filter was used to enhance the retinal images and simplified PCNN was employed to segment the blood vessels by firing neighborhood neurons. Then, fast 2D-Otsu algorithm was introduced to search the best segmentation results and iteration times with less computation time. Finally, the whole vessel network was obtained via analyzing the regional connectivity. Experiments implemented on the public Hoover database indicate that this new method gets a 0.803 5 true positive rate and a 0.028 0 false positive rate on an average. According to the test results, compared with Hoover algorithm and method of PCNN and 1D-Otsu, the proposed method shows much better performance.

Spectral Domain Optical Coherence Tomography of Vogt-Koyanagi-Harada Disease: Novel Findings and New Insights into the Pathogenesis

Objective To provide novel spectral domain optical coherence tomography (SD OCT) findings of Vogt-Koyanagi-Harada (VKH) disease as well as new insights into the pathogenesis of this disease. Methods Detailed SD OCT and fluorescein angiography (FA) findings of 18 consecutive VKH patients (11 women and 7 men) from December 2007 to April 2009 who were in acute uveitic stage at presentation were reviewed. All the patients had been followed up for at least 6 months with reevaluation(s) of SD OCT performed in 10 patients. Results Intraretinal cysts were found to be located in various layers of the outer retina. In addition to the photoreceptor layer, they could also be found between the outer plexiform layer and the outer nuclear layer, or spanning the external limiting membrane. On FA, intraretinal cysts could be hypofluorescent, normofluorescent, or hyperfluorescent. Some intraretinal cysts had a characteristic FA pattern, in which a small round hypofluorescent area was surrounded by a ring of hyperfluorescence (donut-shaped dye pooling). Subretinal fibrinoid deposit appeared in acute uveitic stage in two severe VKH patients and seemed to develop from subretinal exudates and evolved into typical subretinal fibrosis. Gradual transfiguration/migration and progressive proliferation/pigmentation of the subretinal fibrinoid deposit/subretinal fibrosis was observed in one patient. Conclusions Intraretinal cysts could form in various layers of the outer retina and may result from extension of choroidal inflammation. Subretinal fibrosis may develop from subretinal exudates in VKH patients and may cause substantial visual impairment.

Recombinant vascular basement-membrane-derived multifunctional peptide inhibits angiogenesis and growth of hepatocellular carcinoma

AIM： To investigate the anti-angiogenic and antitumor activities of recombinant vascular basement membrane-derived multifunctional peptide （rVBMDMP） in hepatocellular carcinoma （HCC）. METHODS： HepG2, Bel-7402, Hep-3B, HUVE-12 and L-02 cell lines were cultured in vitro and the inhibitory effect of rVBMDMP on proliferation of cells was detected by MTT assay. The in vivo antitumor efficacy of rVBMDMP on HCC was assessed by HepG2 xenografts in nude mice. Distribution of rVBMDMP, mechanism by which the growth of HepG2 xenografts is inhibited, and microvessel area were observed by proliferating cell nuclear antigen （PCNA） and CD31 immunohistochemistry. RESULTS： MTT assay showed that rVBMDMP markedly inhibited the proliferation of human HCC （HepG2, Bel-7402, Hep-3B） cells and human umbilical vein endothelial （HUVE-12） cells in a dose-dependent manner, with little effect on the growth of L-02 cells. When the ICs0 was 4.68, 7.65, 8.96, 11.65 and 64.82 μmol/L, respectively, the potency of rVBMDMP to HepG2 cells was similar to 5-fluorouracil （5-FU） with an IC50 of 4.59 μmol/L. The selective index of cytotoxicity to HepG2 cells of rVBMDMP was 13.8 （64.82/4.68）, which was higher than that of 5-FU [SI was 1.9 （8.94/4.59）]. The VEGF-targeted recombinant humanized monoclonal antibody bevacizumab （100 mg/L） did not affect the proliferation of HepG2, Bel-7402, Hep-3B and L-02 cells, but the growth inhibitory rate of bevacizumab （100 mg/L） to HUVE-12 cells was 87.6% ± 8.2%. AIternis diebus intraperitoneal injection of rVBMDMP suppressed the growth of HepG2 xenografts in a dose-dependent manner, rVBMDMP （1, 3, 10 mg/kg） decreased the tumor weight by 12.6%, 55.9% and 79.7%, respectively, compared with the vehicle control. Immunohistochemical staining of rVBMDMP showed that the positive area rates （2.2% ± 0.73%, 4.5%± 1.3% and 11.5% ±3.8%） in rVBMDMP treated group （1, 3, 10 mg/kg） were significantly higher than that （0.13% ± 0.04%） in the control group （P 〈 0.01）. The positive area rates （19.0% ± 5.7%, 12.2% ± 3.5% and 5.2% ±1.6% ） of PCNA in rVBMDMP treated group （1, 3, 10 mg/kg） were significantly lower than that （29.5% ± 9.4%） in the control group （P 〈 0.05）. rVBMDMP at doses of 1, 3 and 10 mg/kg significantly reduced the tumor microvessel area levels （0.26%± 0.07%, 0.12% ± 0.03% and 0.05% ± 0.01% vs 0.45% ± 0.15%） in HepG2 xenografts （P 〈 0.01）, as assessed by CD31 staining. CONCLUSION： rVBMDMP has effective and unique anti-tumor properties, and is a promising candidate for the development of anti-tumor drugs.

Inhibitory effect of adenoviral vector-mediated AT2R gene transfection on neointimal hyperplasia

Objective: To investigate the effect of adenoviral vector-mediated AT2R gene transfection on neointimal hyperplasia after rat carotid artery balloon injury. Methods :AT2R gene was transferred into rat carotid arteries by recombinant adenovirus pAd-AT2R after the establishment of rat carotid balloon injury restenosis model. The arteries were harvested on the 14th day after gene transfer. The efficiency of trans-gene delivery was measured by the expression of adenovirus-encoding green fluorescent protein (GFP) under fluorescent microscope. The expression of AT2R and PCNA (proliferating cell nuclear antigen) was e-valuated by RT-PCR, immunocytochemistry, immunofluorescence staining, confocal microscopy, respectively. The ratio of intimal to medial area (I/M) was quantified with images and determined by an image analysis system. Results: GFP-positive area in adventitia, media and the forming neointima was about 40%. Adenoviral delivery of rat AT2R gene up-regulated AT2R expression in balloon-injured rat carotid and reduced PCNA expression and I/M significantly in neointima(P<0. 01). Double immunofluorescence labeling of AT2R and PCNA also showed that AT2R gene transfer inhibited VSMCs proliferation in neointima. Conclusion: AT2R gene transfer may be a novel promising therapy to limit neointimal hyperplasia.

Intravascular Ultrasound Image Hard Plaque Recognition and Media-adventitia Border Detection

Intravascular ultrasound (IVUS) is a new technology for the diagnosis of coronary artery disease, and for the support of coronary intervention. IVUS image segmentation often encounters difficulties when plaque and acoustic shadow are present A novel approach for hard plaque recognition and media-adventitia border detection of IVUS images is presented in this paper. The IVUS images were first enhanced by a spatial-frequency domain filter that was constructed by the directional filter and histogram equalization. Then, the hard plaque was recognized based on the intensity variation within different regions that were obtained using the k-means algorithm. In the next step, a cost matrix representing the probability of the media-adventitia border was generated by combining image gradient, plaque location and image intensity. A heuristic graph-searching was applied to find the media-adventitia border from the cost matrix.Experiment results showed that the accuracy of hard plaque recognition and media-adventitia border detection was 89.94% and 95.57%, respectively. In conclusion,using hard plaques recognition could improve media-adventitia border detection in IVUS images.

Computational fluid dynamic simulations on liquid film behaviors at flooding in an inclined pipe

The complex liquid film behaviors at flooding in an inclined pipe were investigated with computational fluid dynamic(CFD) approaches. The liquid film behaviors included the dynamic wave characteristics before flooding and the transition of flow pattern when flooding happened. The influences of the surface tension and liquid viscosity were specially analyzed. Comparisons of the calculated velocity at the onset of flooding with the available experimental results showed a good agreement. The calculations verify that the fluctuation frequency and the liquid film thickness are almost unaffected by the superficial gas velocity until the flooding is triggered due to the Kelvin–Helmholtz instability. When flooding triggered at the superficial liquid velocity larger than0.15 m·s-1, the interfacial wave developed to slug flow, while it developed to entrainment flow when it was smaller than 0.08 m·s-1. The interfacial waves were more easily torn into tiny droplets with smaller surface tension, eventually evolving into the mist flow. When the liquid viscosity increases, the liquid film has a thicker holdup with more intensive fluctuations, and more likely developed to the slug flow.

聚丙烯扁丝的生产工艺

简要介绍聚乙烯和聚丙烯扁丝的生产特点与工艺及发展趋势。

Solution-processed amorphous gallium-tin oxide thin film for low-voltage, high-performance transistors

Gallium-tin oxide(GTO) semiconductor thin films were prepared by spin-coating with 2-methoxyethanol as the solvent. Their crystal structures, optical transparency,chemical states and surface morphologies, along with the electrical properties, were dependent on Ga contents and annealing temperatures. The optimized GTO channel layer was applied in the high-k Al2O3 thin film transistor(TFT) with a low operation voltage of 2 V, a maximum field-effect mobility of 69 cm^2 V^-1 s^-1, a subthreshold swing(SS) of 76 mV dec^-1, a threshold voltage of 0.67 V and an on-off current ratio of 1.8×10^7. The solution-processed amorphousGTO-TFTs would promote the development of low-consumption, low-cost and high performance In-free TFT devices.

Direct fabrication of carbon nanotube-graphene hybrid films by a blown bubble method

Hybridization of carbon nanotubes （CNT） with graphene provides a promising means of integrating the attributes of both materials, thereby enabling widespread application. Here, we present a method to directly assemble hybrid CNT- graphene films by a blown bubble method combined with selective substrate annealing. We use polymethylmethacrylate （PMMA） as the polymeric matrix to blow bubbles containing self-assembled multi-walled CNT arrays, and then transform the bubble film into a CNT-graphene hybrid film by thermal annealing on a Cu substrate; PMMA serves as the carbon source for growing single to few-layer graphene among the CNT network until a continuously hybridized structure is formed. Compared to the bare （non-hybridized） CNT networks, the hybrid films exhibit improved electrical conductivity and structural integrity. Our method also enables the fabrication of a multi-walled CNT-Si solar cell, which has high power conversion efficiency, through the assembly of hybrid CNT-graphene structures.

Transcatheter treatment of Lutembacher syndrome

Lutembacher syndrome, a combination of congenital atrial septal defect （ ASD ） complicated by acquired mitral stenosis, has been traditionally treated by open-heart surgery. With the introduction of transcatheter closure of ASD and percutaneous balloon mitral valvuloplasty, then Lutembacher syndrome can be treated percutaneously. Percutaneous management of Lutembacher syndrome can obviate the morbidity and mortality associated with cardiac surgery, the psychological trauma of a thoracotomy scar and the possibility of repeat thoracotomy for mitral restenosis. So the technique may be ideal for treatment of Lutembacher syndrome.