大气压射流等离子体引发PVC表面接枝聚合季铵盐及其抗菌性的研究

为了提高医用聚氯乙烯(PVC)抗菌性,采用大气压等离子体射流(APPJ)技术对PVC表面接枝并制备季铵盐(QAC)涂层。通过纹影仪和发射光谱仪诊断了等离子体射流的流动状态和活性组分,结合静态水接触角方法、扫描电子显微镜、X射线光电子能谱仪表征和分析APPJ处理前后PVC表面的亲水性、微观形貌和化学组分,并测试了季铵盐/PVC对大肠杆菌的抗菌性能。结果表明,随着放电电压的增大,与PVC接触区域的等离子体射流流动状态从层流向湍流转变,PVC表面亲水性增强,改性后的PVC表面水接触角最低可达26°,含氧官能团含量高达31.02%(原子分数)。放电电压的增大,有助于PVC表面含氧官能团量的提升,并促进季铵盐在PVC表面的接枝和聚合形成致密涂层,提高其对大肠杆菌的抗菌性能。     

丙烯胺等离子体技术对聚碳酸酯聚氨酯的表面改性

利用丙烯胺等离子体表面修饰对聚碳酸酯聚氨酯材料进行改性研究,讨论了改性条件对材料表面亲水性和表面形态的影响,水接触角、扫描电镜(SEM)、X射线光电子能谱(XPS)测试结果表明,预处理气压、处理功率、放电时间对聚氨酯材料表面改性影响较大.经丙烯胺等离子体修饰后,材料表面的亲水性得到改善;表面形态由高度平整、光滑变为粗糙...     

羧甲基化香菇多糖对壳聚糖表面的化学修饰

以壳聚糖为基材,通过表面化学接枝修饰的方法,将羧甲基化香菇多糖固定在壳聚糖基材的表面。通过红外光谱、水接触角测试、抗菌活性及蛋白质吸附等测试方法对修饰后的壳聚糖表面性能进行了表征和分析。测试结果表明,经过表面接枝修饰的壳聚糖基材表面的亲水性得到明显改善,表面纤维蛋白原的吸附量降低了61%,显示出明显的排斥蛋白质非特异性...     

不同气氛低气压电容耦合放电等离子体对聚甲基丙烯酸甲酯表面的改性

利用低气压电容耦合放电等离子体对聚甲基丙烯酸甲酯(PMMA)表面进行亲水改性,对比分析了Ar、N_2、Air和O_2四种等离子体放电气体和不同放电功率对其表面的影响。采用静态接触角、原子力显微镜、X射线光电子能谱分别对PMMA表面亲水性、粗糙程度以及元素和官能团的组成进行了表征。以牛血清蛋白作为标准蛋白,检测处理后PMMA表面蛋白吸附量。结果表明,经等离子体处理后的PMMA表面亲水性和抗蛋白性能均有不同程度的改善,其中Ar等离子体主要起刻蚀的作用,N_2、Air和O_2等离子体在对PMMA刻蚀的同时,接枝的官能团对其表面性能的改变起到主导作用。当等离子体放电功率较低时,增加功率可以显著提高表面亲水性,且亲水性能的提高带动抗蛋白性能的增强。     

远程氩气等离子体引发接枝丙烯酸改性聚丙烯微孔膜的研究

采用远程氩气等离子体对聚丙烯(PP)微孔膜进行表面亲水处理,并引发接枝丙烯酸单体实现永久亲水改性.研究了放电参数及样品位置对于亲水性及接枝率的影响,并运用扫描电镜(SEM)、红外光谱(FTIR)和光电子能谱(XPS)对等离子体处理后的微孔膜进行了表面分析.实验结果显示等离子体功率对处理后的微孔膜的表面亲水性和接枝率有较大影响:在低功率时,放电中心位置的微孔膜经等离子体处理后亲水性最好,同时该位置的接枝率也相应最大;而在高功率时,则是距放电中心20cm位置的微孔膜的亲水性和接枝率优于其他位置.＃红外光谱显示在低功率时膜表面有羧基生成,而在高功率时则仅生成醛基酮基羰基.对于高功率等离子体处理后的PP微孔膜,SEM结果显示在放电中心位置的膜表面有丝状胶合现象发生,XPS结果显示在距放电中心20cm位置处的膜表面含氧量增加最多.     

利用直流辉光放电等离子体改善聚氯乙烯细管内表面亲水性的研究

采用低气压氩气直流辉光放电等离子体对PVC细管内表面进行了处理,使其内表面亲水性得到显著改善,且处理效果均匀.处理时间越长PVC细管内表而的水接触角越小.经过处理后的PVC细管放置室内大气环境后内表面的水接触角出现退化,72小时以后基本稳定,稳定后的内表面水接触角显著好于未经处理的PVC细管.     

大气压介质阻挡放电电学特性及其改性有机薄膜的研究

为了解大气压介质阻挡放电(DBD)的电学特征,通过放电图片、电压-电流曲线、李萨育图形对其进行了诊断,并研究了等离子体参数的影响.同时,本文利用大气压DBD等离子体对PET膜进行了表面改性处理.通过接触角测量仪,衰减全反射-傅里叶变换红外光谱(ATR-FTIR),原子力显微镜(AFM)以及X射线光电子能谱(XPS)对PET表面进行了表征.结果表明:大气压DBD等离子体放电能够有效地改性PET膜,处理后薄膜表面N/C比达到11%左右,薄膜的亲水性也得到较大提高.结论:等离子体放电参数,例如电源频率、气体比例和电源电压等,对放电有较大的影响;其作为一种新兴的等离子体源,可用于有机薄膜的表面改性.     

等离子体处理对PLA膜亲水性及与CNF膜粘附性的影响

目的利用低温等离子体处理PLA膜以提高其亲水性及粘附性,为制备PLA/纳米纤维素复合膜提供一种方法。方法利用单因素试验法探究低温等离子体处理时的放电电压(50～175V)和放电时间(10～50s)对PLA膜表面亲水性和粘附性的影响规律。通过测定PLA膜表面接触角及PLA/纳米纤维素复合膜的剥离强度,分析亲水性及粘附性的变化。利用原子力显微镜观察其微观表面形貌、X射线光电子能谱分析PLA膜表面由疏水性向亲水性转变的机理,并对PLA膜的力学性能及阻隔性能进行分析。结果 PLA膜在低温等离子体条件(放电电压为125V、放电时间为40s、电极距离为4.5cm,氧气流速为1 mL/min,真空度为16.0 kPa)下处理后,其亲水性及与纳米纤维素膜的粘附性达到最佳。此时,PLA膜的接触角由90.0°降至42.4°,PLA/纳米纤维素复合膜的剥离强度为39.5 N/m。结论低温等离子体处理使PLA膜表面由疏水性转变为亲水性,且处理后的PLA可较为牢固地与纳米纤维素膜粘附在一起,从而为PLA/纳米纤维素复合膜的制备提供了一种可行方法。同时,低温等离子体处理对PLA膜的力学性能及阻隔性能没有显著影响。     

RF—PECVD聚合类聚乙烯氧（PEO—like）薄膜及其对血小板吸附性研究

本文采用平板式电容耦合射频(RF,13.56MHz)等离子体源,以乙二醇二甲基醚(Ethylene Glycol DiMethyl Ether)为聚合单体,氩气为辅助气体,在连续与脉冲射频等离子体两种放电模式下合成类聚乙烯氧(PEO-like)功能聚合薄膜.实验研究了等离子体放电参数:等离子体放电功率、工作气压、放电模式(连续或脉冲)和聚合时间等对聚合物表面结构、功能团含量、表面成分性能以及和血小板吸附等影响.利用接触角测定仪(WCA)、傅里叶变换红外光谱(FTIR)、原子力显微镜(AFM)等手段对聚合薄膜的结构、成分和形貌进行细致的分析.同时本文还进行体外细胞培养法,研究了类PEO功能薄膜对富血血小板的吸附,通过倒置显微镜观察细胞黏附的数量和形态变化.得到的结论为:采用RF-PECVD可以在较小功率的连续等离子体放电模式,或较长脉冲间隔的脉冲放电模式下得到结构稳定的PEO生物功能薄膜,所制备的PEO生物功能薄膜具有良好的抗血小板吸附性能.     

低温等离子体处理对纤维毡润湿性能的影响

通过低温等离子体技术对纤维毡进行表面改性,提高其表面润湿性。对未经过任何处理的熔喷聚乙烯纤维毡进行低温等离子体处理,通过接触角测量仪、红外光谱仪和扫描电镜对经过空气等离子体及丙烯酸气相等离子体处理的纤维毡进行表面接触角、官能团以及纤维表面形貌等特征进行表征。结果显示,随着放电时间和放电功率的增加,纤维毡表面亲水性得到了不断提升,改性后的纤维表面接枝了羟基(—OH)、醛基(—CHO)及羰基(C=O)等亲水性官能团,且表面形貌发生了一定的变化,表面微观粗糙度有所增大。这些一系列变化最终使纤维毡表面润湿性得到了有效改善。     

CuO对硬质PVC热解、阻燃和抑烟的锥形量热仪(CONE)研究

通过利用锥形量热仪实验获得的热失重速率,热释放速率,有效燃烧热、烟释放速度和点燃烧时间等参数研究了氧化铜对ＰＶＣ热降解行为,阻燃和抑烟的影响。研究表明,氧化铜促进ＰＶＣ早而快地脱ＨＣｌ,并且明显降低了链段的裂解速度,促进了成碳量的增加。     

Elucidation of reaction mechanisms responsible for afterglow and reagent-ion formation in the low-temperature plasma probe ambient ionization source

The development of ambient desorption/ionization mass spectrometry has shown promising applicability for the direct analysis of complex samples in the open, ambient atmosphere. Although numerous plasma-based ambient desorption/ionization sources have been described in the literature, little research has been presented on experimentally validating or determining the desorption and ionization mechanisms that are responsible for their performance. In the present study, established spectrochemical and plasma physics diagnostics in combination with spatially resolved optical emission profiles were applied to reveal a set of reaction mechanisms responsible for afterglow and reagent-ion formation of the Low-Temperature Plasma (LTP) probe, which is a plasma-based ionization source used in the field of ambient mass spectrometry. Within the dielectric-barrier discharge of the LTP probe, He(2)(+) is the dominant positive ion when helium is used as the plasma supporting gas. This helium dimer ion (He(2)(+)) has two important roles: First, it serves to carry energy from the discharge into the afterglow region in the open atmosphere. Second, charge transfer between He(2)(+) and atmospheric nitrogen appears to be the primary mechanism in the sampling region for the formation of N(2)(+), which is an important reagent ion as well as the key reaction intermediate for the formation of other reagent ions, such as protonated water clusters, in plasma-based ambient ionization sources. In the afterglow region of the LTP, where the sample is usually placed, a strong mismatch in the rotational temperatures of N(2)(+) (B (2)Σ(u)(+)) and OH (A (2)Σ(+)) was found; the OH rotational temperature was statistically identical to the ambient gas temperature (~300 K) whereas the N(2)(+) temperature was found to rise to 550 K toward the tail of the afterglow region. This much higher N(2)(+) temperature is due to a charge-transfer reaction between He(2)(+) and N(2), which is known to produce rotationally hot N(2)(+) (B (2)Σ(u)(+)) ions. Furthermore, it was found that one origin of excited atomic helium in the afterglow region of the LTP is from dielectronic recombination of vibrationally excited He(2)(+) ions.     

The puzzling afterglow of GRB 050721: a rebrightening seen in the optical but not in the X-ray

We present here the analysis of the early and late multiwavelength afterglow emission, as observed by Swift a small robotic telescope and very large telescope (VLT). We compare early observations with late afterglow observations obtained with Swift and the VLT and we observe an intense rebrightening in the optical band at about 1 day after the burst, which is not present in the X-ray band. The lack of detection in X-ray of such a strong rebrightening at lower energies may be described with a variable external density profile. In such a scenario, the combined X-ray and optical observations allow us to derive that the matter density located at approximately 1017 cm from the burst is approximately a factor of 10 higher than in the inner region. This is the first time in which a rebrightening has been observed in the optical afterglow of a gamma-ray burst that is clearly absent in the X-ray afterglow.     

Preparation and characterization of an Hf-doped zinc silicate long-lasting phosphorescent material

Hf⁴⁺-doped Zn₂SiO₄ phosphor emitting long-lasting cyan light was prepared by the conventional high temperature solid-state technique. The emission spectrum of the Hf⁴⁺-doped phosphor exhibits one broad band peaking at 471 nm in the visible region excited by 254 nm. The cyan-light afterglow can last about 40 min in darkness after being irradiated with 254 nm UV lamp for 10 min (250 mW/cm²). The afterglow decay curve can be fitted into a second-order exponential curve. The thermoluminescence (TL) curve shows two glow bands centered at about 386 K (0.61 eV) and 440 K (1.56 eV), respectively, with the lower trap energy level being responsible for the long-lasting afterglow emission. A possible mechanism of the long-lasting phosphorescence based on the experimental results is proposed.     

Properties and Application of Nanocrystalline Poly (vinyl chloride)

The structure and properties of nanocrystalline PVC were investigated. The crystalline region of nanocrystalline PVC was observed by TEM to be 80 nm. The melting point of nanocrystalline PVC was found to be 128℃which is obviously lower than typical PVC (210℃). The X-ray diagrar indicated that the crystal existed in nanocrystalline PVC. The evident effect of self-plasticizing and reinforcement appeared when nanocrystalline PVC was added. The optimum amount for self-plasticizing is about 10%. The maximal impact strength of 95.1 kJ/m2 was achieved by adding 20% nanocrystalline PVC and tensile strength with 56.2 MPa which was 122% of pure PVC was obtained after adding 5% nanocrystalline PVC.     

新型彩色长余辉材料的制备及其发光性能的研究

将红色染料罗丹明B与绿色长余辉材料混配间接获得可被可见光激发的橙红色长余辉材料,并在此基础上根据三基色原理得到了一系列彩色长余辉发光材料,同时对其发光性能进行了系统研究.通过对材料的余辉谱以及余辉曲线分析,发现随着加入的蓝、绿色长余辉材料与罗丹明B相对浓度的变化,其位于510和580nm左右的余辉光谱特征峰分别发生一定...     

Room-Temperature Phosphorescence Resonance Energy Transfer for Construction of Near-Infrared Afterglow Imaging Agents

Afterglow imaging that detects photons after cessation of optical excitation avoids tissue autofluorescence and thus possesses higher sensitivity than traditional fluorescence imaging. Purely organic molecules with room-temperature phosphorescence (RTP) have emerged as a new library of benign afterglow agents. However, most RTP luminogens only emit visible light with shallow tissue penetration, constraining their in vivo applications. This study presents an organic RTP nanoprobe (mTPA-N) with emission in the NIR range for in vivo afterglow imaging. Such a probe is composed of RTP molecule (mTPA) as the phosphorescent generator and an NIR-fluorescent dye as the energy acceptor to enable room-temperature phosphorescence resonance energy transfer (RT-PRET), ultimately resulting in redshifted phosphorescent emission at 780 nm. Because of the elimination of background noise and redshifted afterglow luminescence in a biologically transparent window, mTPA-N permits imaging of lymph nodes in living mice with a high signal-to-noise ratio. This study thus opens up a universal approach to develop organic RTP luminogens into NIR afterglow imaging agents via construction of RT-PRET.     

蓝光激发余辉型荧光粉的研究进展

白光LED具有节能、环保、响应速度快等优点,逐渐成为新一代照明光源,其普遍采用蓝光LED芯片激发黄色YAG∶Ce3+荧光粉合成白光的模式。由于这类LED加入直流(DC)/交流(AC)转换器和散热器,使得市售灯具价格偏高,严重阻碍了白光LED的进一步推广。AC-LED采用市电直接驱动,是LED发展的必然方向,余辉型荧光粉使得AC-LED变成了可能。主要针对应用于AC-LED的具有蓝光激发余辉功能的荧光粉的国内外研究现状进行了总结,并对用于消除LED频闪的余辉发生时间、余辉时间长度进行了计算,对余辉强度、余辉衰减速率进行了初步判断,得出荧光粉的余辉时间为6.67ms≤Tx≤10ms,余辉强度最小值需大于0.032mcd/m2,余辉衰减速率满足式(1),且余辉发生在T/2~2T/3时对于消除频闪最有益。     

Luminescent properties of a reddish orange emitting long-lasting phosphor CaO:Pr

A novel reddish orange emitting long persistent phosphor CaO:Pr was prepared by a high temperature solid-state reaction method. All as-prepared phosphors were studied systematically by X-ray diffraction, photoluminescence (PL) spectra, decay curves, afterglow spectra and thermoluminescence (TL) glow curves. The intensity of PL and the performance of afterglow are dependent on the concentration of Pr³⁺ ions. The trap depth in the range between 0.5 and 0.7 eV is suitable for long afterglow (LAG). The optimal concentrations of Pr³⁺ ions for the best characteristic PL emission and afterglow were experimentally calculated to be 0.05 mol%. After irradiation by 273 nm for 3 min, the duration of reddish orange afterglow can last nearly 1 h. The decay processes and mechanism of LAG in CaO:Pr³⁺ were also discussed in detail.     

Phase separation in blends of oligo (caprolactone glycol)-based polyurethane with poly(vinyl chloride)

The structure of o!igo (caprolactone glycol)-based polyurethane-poly(vinyl chloride) (PVC) blends obtained from tetrahydrofuran solution was studied by X-ray diffraction and electron microscopy. The system is characterized by a oornp!ex phase diagram with two types of equilibria: (1) crystal-liquid equilibrium in the region of blend compositions up to 40 wt% PVC; (2) liquid-liquid equilibrium in the region of man compositions. The crystallization kinetics of oligo(caprolactone) polyurethane blocks from an initially compatible amorphous blend was investigated. Small-angle X-ray cattering (SAXS) studies provide evidence that the amorphous component (PVC) is incorporated in the interlamellar crystalline regions of the compositions. The amorphous blends are characterized by the presence of modulated structures at two scale levels, this being explained as e result of the process in which the bulk samples were obtained from a three-component polymer-polymer-solvent system.