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51.
A novel and effective protocol for the preparation of superparamagnetic immunomicrospheres has been developed. First, micro‐size magnetic poly (methacrylate‐divinylbenzene) (PMA‐DVB) spheres were prepared by a modified suspension polymerization method. The oleic acid coated magnetite (Fe3O4) nanoparticles made by coprecipitation were mixed with monomers of MA, DVB, and initiator benzoyl peroxide (BPO) to form oil in water emulsion droplets with the presence of poly (vinyl alcohol) (PVA‐1788) as a stabilizer. The polymerization reaction was carried out in a 2‐L beaker equipped with four vertical stainless steel baffleplates by increasing the temperature of the mixture at a controlled rate. The resulting magnetic microspheres are micro‐sized (less than 8μm in diameter) and 80 percent of them are in the size ranging from 1 to 5 μm. Then, they were highly functionalized via ammonolysis reaction with ethylenediamine, and the surface amino‐modified magnetic microspheres were obtained. The morphology and properties of these magnetic microspheres were examined by SEM, TEM, VSM, and FT‐IR. Affinity ligand protein A (ProtA) was covalently immobilized to the amino‐modified magnetic microspheres by the glutaraldehyde method. These ProtA‐immobilized magnetic immunomicrospheres were effective for affinity bioseparation processes, as was demonstrated by the efficient immunoaffinity purification of antibodies IgG2a (22mg per gram of microspheres) from mouse ascites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2205–2211, 2004 相似文献
52.
L. T. Guan F. G. Du G. Z. Wang Y. K. Chen M. Xiao S. J. Wang Y. Z. Meng 《Journal of Polymer Research》2007,14(3):245-251
Completely biodegradable foams of poly(propylene carbonate) (PPC) derived from carbon dioxide and propylene oxide were fabricated
using N, N′-dinitroso pentamethylene tetramine (DPT) as chemical blowing agent, and urea as the activator to lower the decomposition
temperature of DPT. Thermal decomposition behavior and gas evolution behavior of the DPT composite with various urea to DPT
ratios were investigated to optimize the composition of the blowing agent. The formulation of blowing agent mixture and foaming
condition, the foam morphologies, the molecular weight change, as well as the mechanical properties of produced PPC foams
were studied extensively. The experimental results demonstrated that the greatest blowing ratio of 14.8 can be afforded in
case 12 phr blowing agent was used at 170 °C for 30 min. Gel permeation chromatography (GPC) and thermal analysis revealed
that DPT acted as both chain-extension agent and blowing agent for PPC matrix. The molecular weight of PPC subjected to foaming
increased by 76%. The foamed PPC exhibited superior mechanical properties and can be used as packaging material for many practical
applications. 相似文献
53.
Dynamic images that possess beauty and are user-friendly can increase the use of digital technology. In addition to information conveyance, dynamic images also act as a communication bridge in the human–machine interface. Dynamic images are widely used in the application of digital media. Therefore, understanding the visual effects of dynamic images on viewers is a very important issue. From a visual communication design perspective, dynamic images influence not only image quality, but also the viewers’ perception and impression of the displayed image. In the contemporary age characterized by universal usage of dynamic images, designers should attain synchronized knowledge and understanding of relevant media technology so as to present preferred design quality in the management of digital design such as animation design, Web page design, multimedia design, and so on. The current study noted that psychological effects such as viewers’ visual attention, preferences, and understanding were more important than image quality. Therefore, this study adopted the viewpoint of “visual design” and conducted a perceptual evaluation of grating frequency and grating velocity. The pair-comparison method and scale method were adopted in the research methodology to simplify perceptual evaluations and enhance their validity. The purpose of this study was: (1) To propose recommendations for displaying dynamic images and improving image performance using perceptual evaluation methods. (2) To examine the influence of psychological factors on viewer’s comfort when they experience dynamic images. (3) To identify the best grating feature combinations that meet viewer’s psychological characteristics and propose recommendations for dynamic images design. The study concludes that it is useful to establish criteria for evaluating users’ perception and to, develop perceptual evaluations of dynamic images. It is recommended that designers find a balance between watching a moving imaging display “clearly” and watching it “comfortably” for successful reception by the viewer. 相似文献
54.
Weizeng Shao Susanne Lehner Changlong Guan 《International journal of remote sensing》2014,35(11-12):4046-4063
In this article, the polarization ratio (PR) of TerraSAR-X (TS-X) vertical–vertical (VV) and horizontal–horizontal (HH) polarization data acquired over the ocean is investigated. Similar to the PR of C-band synthetic aperture radar (SAR), the PR of X-band SAR data also shows significant dependence on incidence angle. The normalized radar cross-section (NRCS) in VV polarization data is generally larger than that in HH polarization for incidence angles above 23°. Based on the analysis, two PR models proposed for C-band SAR were retuned using TS-X dual-polarization data. A new PR model, called X-PR hereafter, is proposed as well to convert the NRCS of TS-X in HH polarization to that in VV polarization. By using the developed geophysical model functions of XMOD1 and XMOD2 and the tuned PR models, the sea surface field is retrieved from the TS-X data in HH polarization. The comparisons with in situ buoy measurements show that the combination of XMOD2 and X-PR models yields a good retrieval with a root mean square error (RMSE) of 2.03 m s–1 and scatter index (SI) of 22.4%. A further comparison with a high-resolution analysis wind model in the North Sea is also presented, which shows better agreement with RMSE of 1.76 m s–1 and SI of 20.3%. We also find that the difference between the fitting of the X-PR model and the PR derived from TS-X dual-polarization data is close to a constant. By adding the constant to the X-PR model, the accuracy of HH polarization sea surface wind speed is further improved with the bias reduced by 0.3 m s–1. A case acquired at the offshore wind farm in the East China Sea further demonstrates that the improvement tends to be more effective for incidence angles above 40°. 相似文献
55.
56.
压痕残余应力对氮化硅基复合材料阻力曲线行为的影响 总被引:3,自引:1,他引:3
通过压痕小裂纹直接量测法获得了TiC,TiN/Si3N4复合材料的阻力曲线,采用更具合理性的指数经验公式拟合处理实验数据,初步探讨了K∞,K^*R,ΔC,等参数的物理意义。对压痕残余应力消除前 实验结果进行比较,发现压痕残余应力的消除,提高了材料的极限断裂韧性值K^*R,却大大减少了裂纹稳态生长的容限,使得材料的脆性行为更为突出。 相似文献
57.
尿基复合肥生产技术的改进 总被引:1,自引:0,他引:1
通过分析尿基复合肥生产过程中出现的问题,并相应提出技术改进措施,优化操作,对复合肥产量的提高和产品质量的控制都取得了明显的效果。 相似文献
58.
59.
From in situ polycondensation, a poly(ethylene terephthalate)/Polyamide 6 copolymer/montmorillonite nanocomposite was prepared, after the treatment of montmorillonite (MMT) with a water soluble polymer. The resulting nanocomposites were characterized by X‐ray diffraction (XRD), differential scanning calorimeter (DSC), nuclear magnetic resonance (NMR), dynamic mechanical analysis (DMA), and transmission electron microscopy (TEM). The results of DSC, 1H NMR, and DMA proved that the nanocomposite synthesized was PET/PA6 copolymer/MMT nanocomposite, not the PET/PA6 blend/MMT nanocomposite. The results of XRD and TEM proved that the dispersion of MMT was improved observably after the introduction of PA6 molecular chain into PET. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2512–2517, 2006 相似文献
60.
A novel method for the preparation of a quaternary ammonium ionomer of styrene–butadiene–styrene triblock copolymer (SBS) was developed by a ring‐opening reaction of epoxidized SBS with triethylamine hydrochloride in the presence of a phase transfer catalyst. The optimum conditions were studied. The ionomer was characterized by quantitative analysis, IR spectroscopy, and 1H‐NMR spectroscopy. Its water absorbency, oil absorbency, dilute solution viscosity, and use as a compatibilizer for the blending of SBS and chlorosulfonated polyethylene (CSPE) were investigated. The results showed that, under optimum conditions, the epoxy groups can be completely converted to the quaternary ammonium groups. The IR spectrum did not exhibit the absorption peak for quaternary ammonium groups, whereas the 1H‐NMR spectrum and titration method demonstrated it. With increasing ionic group content, the water absorbency of the ionomer increased whereas its oil absorbency decreased. These indicated the amphiphilic character of the SBS ionomer. The dilute solution viscosity of the ionomer in toluene/methanol (9/1) solvent increased with increasing quaternary ammonium group content. The ionomer was used as a compatibilizer for the blends of SBS and CSPE. The addition of a small amount of the ionomer to the blend enhanced the mechanical properties of the blends: 2 wt % ionomer based on the blend increased the tensile strength and ultimate elongation of the blend nearly 2 times. The blends of equal parts SBS and CSPE behaved as oil‐resistant thermoplastic elastomers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1975–1980, 2006 相似文献