Tristable switching of the electrical conductivity through graphene quantum dots sandwiched in multi-stacked poly(methyl methacrylate) layers

Tristable switching nonvolatile memory (NVM) devices based on graphene quantum dots (GQDs) sandwiched between multi-stacked poly (methyl methacrylate) (PMMA) layers were fabricated on indium-tin-oxide (ITO)-coated glass substrates by using a solution-processed method. Current-voltage (I-V) curves at 300 K for the silver nanowire/PMMA/GQD/PMMA/GQD/PMMA/ITO/glass devices showed tristable switching currents with high-resistance, intermediate-resistance, and low-resistance states. The device's cycling endurance of the three resistance states remained stable with a distinguishable value for each resistance state over 1000 cycles, and the obtained retention results showed well-distinguished resistance states without degradation for up to 1 × 10⁴ s. Schottky emission, Poole-Frenkel emission, trapped-charge limited-current, and ohmic conduction were proposed as the dominant conduction mechanisms for the fabricated NVM devices based on the obtained I-V characteristics. The described energy-band diagrams confirm the proposed conduction band mechanisms.     

MPPA光动力作用诱导人鼻咽癌细胞凋亡的实验研究

为观察MPPa光动力作用对鼻咽癌细胞凋亡的影响,应用AnnexinV—PI双染结合流式细胞仪分析MPPa光动力作用后人鼻咽癌细胞株CNE2细胞发生凋亡和继发性坏死的比率。结果显示MPPa光动力作用实验组人鼻咽癌细胞株CNE2细胞发生凋亡和继发性坏死的比率分别增加到16.43 %和4.64 % ,且均显著高于单纯光照射组、单纯MMPa光敏剂处理组和假照射组(P <0 .0 1) ,而三对照组间无明显差异(P >0 .0 5 )。表明MPPa光动力作用能有效诱导低分化人鼻咽癌细胞株CNE2细胞凋亡的发生。这也可能是MPPa光动力作用杀伤鼻咽癌的重要机制之一。     

Cover Picture: Toward Large‐Scale Alignment of Electrohydrodynamic Patterning of Thin Polymer Films (Adv. Funct. Mater. 15/2006)

By integrating lithography and self‐assembly via electrohydrodynamic instabilities, Russel and co‐workers are able to guide initially flat polymer films to evolve into periodic arrays of pillars over regions much greater in extent than their natural domain sizes, as detailed on p. 1992. Novel structures that involve a combination of linear ridges and pillars are also produced, mainly as as result of the dynamic merging among preformed pillars. To pattern thin polymer films via electrohydrodynamic instabilities, we design and utilize two different kinds of mask patterns to guide pillars into alignment over regions much greater in extent than their natural domain sizes. First, narrow protruding ridges that intersect to form regular patterns on the mask trigger the growth of pillars beneath. Later, square and triangular packings of pillars develop in the regions enclosed by those ridges, preserving the registry from one domain to the next over a much larger area than within individual domains in unpatterned portions of the mask. Second, small square protrusions that are prealigned into a large regular array on the mask guide the formation of square packings of pillars in domains that conform to the mask, forming a large array of pillars. Novel structures involving a combination of linear ridges and pillars are also produced mainly due to the dynamic merging among preformed pillars. Finally, we find vertex symmetry of the mask pattern is necessary for generating and preserving ordered patterns on the polymer film.     

Intramolecular Donor–Acceptor Regioregular Poly(3‐hexylthiophene)s Presenting Octylphenanthrenyl‐Imidazole Moieties Exhibit Enhanced Charge Transfer for Heterojunction Solar Cell Applications

Intramolecular donor–acceptor structures prepared by covalently binding conjugated octylphenanthrenyl‐imidazole moieties onto the side chains of regioregular poly(3‐hexylthiophene)s exhibit lowered bandgaps and enhanced electron transfer compared to the parent polymer, e.g., conjugation of 90 mol% octylphenanthrenyl‐imidazole moieties onto poly(3‐hexylthiophene) chains reduces the optical bandgap from 1.91 to 1.80 eV, and the electron transfer probability is at least twice as high as that of pure poly(3‐hexylthiophene) when blended with [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester. The lowered bandgap and the fast charge transfer both contribute to much higher external quantum efficiencies, thus much higher short‐circuit current densities for copolymers presenting octylphenanthrenyl‐imidazole moieties, relative to those of pure poly(3‐hexylthiophene)s. The short‐circuit current density of a device prepared from a copolymer presenting 90 mol% octylphenanthrenyl‐imidazole moieties is 13.7 mA · cm^?2 which is an increase of 65% compared to the 8.3 mA · cm^?2 observable for a device containing pure poly(3‐hexylthiophene). The maximum power conversion efficiency of this particular copolymer is 3.45% which suggest that such copolymers are promising polymeric photovoltaic materials.     

硫代异丙醇的气相色谱分析

利用 GC9800TFP 型气相色谱仪,使用 SE-54型毛细管色谱柱,丙酮作内标物,建立了硫脲法和 NaHS法合成硫代异丙醇的色谱分析方法。在柱温50℃、气化室温度150℃、检测器温度150℃、载气流速1 mL/min 的条件下,色谱分离效果好。硫代异丙醇与内标物的相对浓度比在0.046 2～0.334 0范围内,方法的线性相关系数为0.999 6,回收率为96.26%～101.05%,标准偏差为0.079 26,变异系数为0.041 0。     

流动注射在线富集分离－分光光度法测定矿石和矿渣中微量金

本文研究了矿石、矿渣中微量金的测定。使用５２０９萃淋树脂柱、流动注射在线富集分离金，用亚硫酸钠解吸，在一定酸度和表面活性剂曲拉通Ｘ－１００存在下，与ＴＭＫ在常温下络合显色，于５４５ｕｍ波长处测定吸光度。金浓度范围在０．０２～０．６０μｇ／ｍＬ呈线性关系。测定下限为０．０２ｇ／ｔ，样品的精密度优于±５％，回收率为１０１％～１０６％。     

Effects of Microwave on Drug Release Property of Poly(Methyl Vinyl Ether-co-Maleic Acid) Matrix

ABSTRACT

The drug release behavior of beads made of poly(methyl vinyl ether-co-maleic acid) was investigated with respect to the influence of microwave irradiation. The beads were prepared by an extrusion method with sodium diclofenac as a model water-soluble drug. The beads were subjected to microwave irradiation at 80 W for 5 and 20 min, and at 300 W for 1 min 20 s and 5 min 20 s. The profiles of drug dissolution, drug content, drug-polymer interaction, and polymer-polymer interaction were determined by using dissolution testing, drug content assay, differential scanning calorimetry, and Fourier transform infra-red spectroscopy. Keeping the level of supplied irradiation energy identical, treatment of beads by microwave at varying intensities of irradiation did not bring about similar drug release profiles. The extent and rate of drug released from beads were markedly enhanced through treating the samples by microwave at 80 W as a result of loss of polymer-polymer interaction via the (CH₂)_n moiety, but decreased upon treating the beads by microwave at 300 W following polymer-polymer interaction via the O-H, COOH, and COO^? moieties as well as drug-polymer interaction via the N-H, O-H, COO^?, and C-O moieties. The beads treated by microwave at 300 W exhibited a higher level of drug release retardation capacity than those that were treated by microwave at 80 W in spite of polymer-polymer interaction via the (CH₂)_n moiety was similarly reduced in the matrix. The mechanism of drug release of both microwave-treated and untreated beads tended to follow zero order kinetics. The drug release was markedly governed by the state of polymer relaxation of the matrix and was in turn affected by the state of polymer-polymer and/or drug-polymer interaction in beads.     

聚苯胺/凹凸棒纳米纤维的制备及性能研究

使用硅烷偶联剂苯胺甲基三乙氧基硅烷(AMTES)改性凹凸棒粘土(ATP),制备了表面具有自组装单片层的SAM-ATP,并以其为模板,制备了结构较为均一的SAM-ATP/PANI纳米纤维。对制备工艺中SAM-ATP的用量进行了探讨,研究表明,当SAM-ATP含量为15.4%(质量分数)时,SAM-ATP/PANI纳米纤维结构较为均一、分散性良好,且具有最好的室温电导率2.3×10-4S/cm,使用紫外-可见分光光度计(UV-Vis)对电导率的变化原因进行了分析,使用热重分析仪(TGA)对材料的热稳定性进行了探讨,研究显示SAM-ATP的引入可有效提高PANI热稳定性。使用傅立叶变换红外分光光度计(FT-IR)和透射电子显微镜(TEM)对SAM-ATP/PANI纳米复合材料的结构和形貌进行了表征。     

新型耐高温复合反渗透膜的制备与性能

以杂萘联苯聚芳醚腈酮超滤膜为基膜,间苯二胺作为水相单体、均苯三甲酰氯作为有机相单体,通过界面聚合法制备了新型耐高温聚芳香酰胺复合反渗透膜.研究了单体浓度、反应时间对膜性能的影响,用扫描电子显微镜和红外光谱仪表征了界面聚合反应前后膜表面形貌和化学结构的变化,并对膜的耐高温性能进行了考察.随着操作温度从20℃升高到95℃,膜的脱盐率保持在97.9%,通量从7.4 L/(m~2·h)上升至31.4 L/(m~2·h);膜在沸水中煮沸至3 h,其脱盐率基本不变而通量先增加后趋于稳定,表明杂萘联苯聚芳醚腈酮复合反渗透膜具有优良的耐高温性能.     

茉莉酸甲酯对鲜切苹果生理生化变化的影响

为研究茉莉酸甲酯(MeJA)对鲜切苹果生理生化变化的影响,将1cm3的鲜切富士苹果分别放入100、400、1600μmol/L的茉莉酸甲酯溶液中浸泡30min,包装后放入5℃冷库中贮藏。每2d测定各类酶活性以及与成熟衰老相关的指标等的变化。结果表明,经茉莉酸甲酯处理后,鲜切苹果的APX活性降低,但LOX、PAL、CAT、PPO、POD活性增加,相对电导率和丙二醛含量降低,说明茉莉酸甲酯处理启动了鲜切富士苹果的防御反应,导致相关防御反应的关键酶活性升高,从而降低机械伤害引发的自由基对细胞膜产生的伤害。研究认为,鲜切苹果贮前经适当浓度的茉莉酸甲酯溶液浸泡,可显著延长贮藏期和保持新鲜品质。