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排序方式: 共有135条查询结果,搜索用时 0 毫秒
41.
The {[PdPW11O39]5–/Pt/PAMAM}n multilayer composites constructed from G4.0 Amino‐terminated poly (amidoamine) dendrimer (PAMAM), Pt and Keggin‐type palladium(II)‐substituted polyoxometalates anion ([PdPW11O39]5–) were prepared via layer by layer electro‐depositing technique. The X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), and field emission scanning electron microscope (FE‐SEM) characterization indicate that the Pt nanoparticles have been anchored on the as‐prepared nanocomposites. And the morphologies of Pt nanoparticles are influenced by deposition potential, the number of layers of {[PdPW11O39]5–/Pt/PAMAM}n multilayer nanocomposites, and the existence of PAMAM. The electrocatalytic properties and stability of {[PdPW11O39]5–/Pt/PAMAM}n multilayer nanocomposites were investigated by cyclic voltammetry. Experimental investigation results reveal that PAMAM is a good support for Pt nanoparticle growth due to its interior cavity structure and high stability. [PdPW11O39]5– play an important role to prevent intermediate product (mainly as CO) in the methanol oxidation from poisoning the as‐prepared catalyst. The {[PdPW11O39]5–/Pt/PAMAM}3/GC shows better electrocatalytic properties, stability, and CO tolerance ability than Pt/GC and {Pt/PAMAM}3/GC fabricated by similar electrodeposition processes. 相似文献
42.
ABSTRACT Based on its excellent damping properties, traditional rubber has been widely used in various industries, including aerospace, rail transit and automotive. However, the disadvantages of effective damping area, unstable damping performance, easy fatigue, and aging, greatly limited the further application of rubber materials. Thus, it is important to develop novel modified rubber damping materials. Herein, polyamidoamine dendrimers with terminal-modified phenolic hydroxyl and amine groups (G2 PAMAM-H) were designed and used as modifiers to improve the damping performance of chlorinated butyl rubber (CIIR). The results showed that the modification of G2 PAMAM by diphenolic acid can avoid its aggregation in the CIIR matrix. CIIR/G2 PAMAM-H nanocomposites exhibited high tan δ max of 1.52 and wide damping temperature region of 140°C (tan δ > 0.55)at a very low loading (4.32 wt.%), which were strongerthan that of pure CIIR and CIIR/G2 PAMAM nanocomposites. In addition, these nanocomposites also exhibited a unique self-healing ability by multiple hydrogen bonds, which can effectively extend the life of the rubber material in actual production. Therefore, the dendrimer modification provided unique development opportunities for elastomers in certain highly engineered fields, such as vehicles, rail transit, aerospace, etc. 相似文献
43.
Julio César Ramírez-Arroniz Elena Martínez Klimova Luis Daniel Pedro-Hernández Ulises Organista-Mateos Sandra Cortez-Maya Teresa Ramírez-Ápan 《Drug development and industrial pharmacy》2018,44(8):1342-1349
p-[bis(chloro-2-ethyl)amino]-L-phenylalanine (melphalan) is an approved anti-cancer agent with a broad spectrum of antitumor activity. However, it has some disadvantages, such as poor water-solubility followed by rapid elimination, which reduce the target specificity. To solve these problems, porphyrin- poly(amidoamine) or PAMAM-conjugates of melphalan were synthesized and characterized. The dendrimeric conjugates showed satisfactory water solubility. It was found that the size of the dendrimer played a crucial role in controlling the drug content and diameter of the melphalan-conjugates. The in vitro studies of cell cytotoxicity revealed that by employing the dendrimeric conjugation strategy and using the PAMAM dendritic arms as spacers, the conjugates had good anti-cancer activity and lower toxicity than free melphalan. 相似文献
44.
PA6/PAMAM共混物的加工与流变性能 总被引:3,自引:0,他引:3
研究了不同代数、不同用量的PAMAM树形分子对PA6/PAMAM共混物加工和流变性能的影响。结果表明:在PA6中加入少量的PAMAM树形分子即可显著提高PA的流变性能和加工性能,PAMAM可作为PA6的流变学改性剂和新型加工助剂。 相似文献
45.
Metal Ion/Dendrimer Complexes with Tunable Work Functions in a Wide Range and Their Application as Electron‐ and Hole‐Transport Materials of Non‐Fullerene Organic Solar Cells 下载免费PDF全文
The work functions of electrodes can be modified by adding charge transport layers to have good energy level matching with the active materials for organic solar cells (OSCs). Usually, a certain material gives rise to one definite work function of an electrode. In this work it is demonstrated that complexes of poly(amido amine) (generation 3) (PAMAM) with Cu2+ can continuously tune the work function of indium tin oxide (ITO) in a range of 4–5 eV by controlling the ratio of Cu2+ to PAMAM. PAMAM can lower the work function of ITO from 4.60 to 4.07 eV, while Cu2+‐PAMAM can increase the work function. The work function increase depends on the Cu2+‐to‐PAMAM molar ratio, and the work function can be up to 4.96 eV. The Cu2+ effect is ascribed the Cu2+‐caused change in the dipole moment of PAMAM. Moreover, this method can be used to continuously modify the work function of other materials, including Ag, Au, poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate, and reduced graphene oxide. In addition, PAMAM and Cu2+‐PAMAM are investigated as the charge collection buffer materials of non‐fullerene OSCs of poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione))]: 3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene). The power conversion efficiency can reach 9.2%, which is comparable to that using conventional charge transport materials. 相似文献
46.
Solid-phase PAMAM dendrimer was synthesized by the repetitive addition of a branching unit to silica gel. All synthesis steps
were monitored by infrared spectroscopy to investigate the reaction rate. Based on the measurements of infrared spectra, which
showed the ester group varied as a function of reaction time, a reaction kinetics model was proposed and simulated. FT-IR
and TGA measurements suggested that a ‘cross-linking’ reaction occurred in amidation process and generated structural defects,
which decreased the grafted amount of dendrimer on silica gel. In addition, the analysis of reaction rate constants indicated
that due to the formation of an intermediate, Michael addition of methyl acrylate to diamine was probably hindered by steric
crowding.
This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University. 相似文献
47.
Hamed Nosrati Maral Adibtabar Ali Sharafi 《Drug development and industrial pharmacy》2018,44(8):1377-1384
Denderimer-modified magnetic nanoparticles are a promising drug delivery nanosystem which can improve the therapeutic efficacy of chemotherapy drugs and can also be beneficial as magnetic resonance (MR) images contrast agent. The present study introduces the preparation and characterization of the potential therapeutic efficiency of curcumin (CUR)-loaded denderimer-modified citric acid coated Fe3O4 NPs. Polyamidoamine (PAMAM, generation G5) was used to encapsulate citric acid coated Fe3O4 nanoparticles. The successful preparation of CUR-loaded nanocarriers were confirmed by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and transmission electron microscopy (TEM) techniques. The loading capacity and encapsulation efficiency of CUR molecules were 12?±?0.03% and 45.58?±?0.41%, respectively. The anticancer effect of void CUR and CUR-loaded nanocarriers were compared to each other by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on treated MCF-7 cell line. It can be concluded that application of nanoparticles can be more effective strategy for controlled and slow release of CUR in human breast cancer treatment. 相似文献
48.
49.
以端氢聚二甲基硅氧烷(HTPDMS)和烯丙基缩水甘油醚(AGE)为原料,利用硅氢加成反应合成出单端环氧基聚二甲基硅氧烷(SEPDMS),再将其接枝到一代树枝状聚酰胺-胺(G1 PAMAM)上,制备出聚硅氧烷改性的树枝状-线性聚合物(G1 PAMAM-Si)。通过傅里叶红外光谱(FTIR)、核磁共振氢谱(1HNMR)及纳米粒度分析仪表征分析了产物的结构及乳液性能。将G1 PAMAM-Si应用于皮革加脂工序,并使用扫描电镜(SEM)、X射线衍射谱图分析手段考察了加脂后皮革样品的结构与性能。结果表明,G1 PAMAM-Si加脂后革样胶原纤维间距增大,纤维排列无序度增加。柔软度增加至6.07 mm,抗张强度为17.43 MPa,且撕裂强度增加至94.97 N/mm。 相似文献
50.
In this study, a copper/poly(amidoamine)/multi-walled carbon nanotube/reduced graphene oxide (Cu/PAMAM/MWCNT/rGO) complex was synthesized for fabricating an electrochemical sensor to simultaneously detect nitrate and nitrite ions as inorganic contaminants, and 4-chlorophenol (4-CP) and 1,2,5,8 tetrahydroxy anthraquinone (THA) as organic pollutants. The prepared Cu/PAMAM/MWCNT/rGO electrode was characterized using scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS). Cyclic voltammetry (CV) was performed to investigate the influence of the pH of the solution, concentration of anions, and scan rate on the analytical performance of the electrodes. The simultaneous determination of nitrite/nitrate ions using a Cu/PAMAM/MWCNT/rGO electrode showed sensitivities of 8.030 × 10−3 and 5.370 × 10−3 μA μM−1 mm−2, and limits of detection (LODs) of 0.081 and 0.115 μM, respectively. For the simultaneous determination of 4-CP/THA, the sensitivities of the modified electrode were 0.0105 and 9.399 × 10−3 μA μM−1 mm−2, and detection limits were 0.062 and 0.070 μM respectively. 相似文献