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91.
Synthesis of chalcone‐containing methacrylate‐based hydrogen bonded side chain liquid crystalline polymer and its dielectric properties 下载免费PDF全文
Burak Korkmaz Yesim Hepuzer Gursel Nimet Yilmaz Canli Zeynep Güven Özdemir Mustafa Okutan Bahire Filiz Senkal 《先进技术聚合物》2017,28(11):1351-1356
In this work, a new methacrylate‐based hydrogen bonded side chain liquid crystalline polymer having chalcone moieties (HBCP) was prepared from poly(4‐(3‐(pyridin‐4‐yl)acryloyl) phenyl methacrylate) and 11‐(4‐cyanobiphenyl‐4(‐oxy) undekan‐1‐ol (LC11)) by molecular self‐assembly processes via hydrogen bond formation between nitrogen of the HBCP and hydroxyl group of the LC11. The formation of H bond was confirmed by using Fourier transform infrared (FTIR) spectroscopy. The phase transition temperatures and liquid crystalline phases of the HBCP were examined by DSC and POM measurements. The dielectric properties of HBCP have been determined by impedance analyzer within the frequency interval of 100 Hz–15 MHz. According to Cole–Cole plot, the equivalent circuit of the LC system has been found as a capacitor in parallel with a resistor. The resonance frequency, fr, of the R–C circuit has also been calculated as 1.59 MHz by phase angle versus frequency curve. The dielectric relaxation type of HBCP has been determined as nearly‐Debye type because the absorption coefficient, α, equals to 0.01655. From the conductivity point of view, HBCP displays dc conductivity at the low and high frequency regions that correspond to 100 Hz–12 kHz and 3.3 MHz–15 MHz, respectively. On the other hand, it has been revealed that the ac conductivity of the LC system investigated obeys Super Linear Power Law (SLPL) at the intermediate frequency domain. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
92.
Molecularly Imprinted Polymer Nanomaterials and Nanocomposites: Atom‐Transfer Radical Polymerization with Acidic Monomers 下载免费PDF全文
Zeynep Adali‐Kaya Dr. Bernadette Tse Sum Bui Dr. Aude Falcimaigne‐Cordin Prof. Karsten Haupt 《Angewandte Chemie (International ed. in English)》2015,54(17):5192-5195
Molecularly imprinted polymers (MIPs) are artificial receptors which can be tailored to bind target molecules specifically. A new method, using photoinitiated atom‐transfer radical polymerization (ATRP) for their synthesis as monoliths, thin films and nanoparticles is described. The synthesis takes place at room temperature and is compatible with acidic monomers, two major limitations for the use of ATRP with MIPs. The method has been validated with MIPs specific for the drugs testosterone and S‐propranolol. This study considerably widens the range of functional monomers and thus molecular templates which can be used when MIPs are synthesized by ATRP, as well as the range of physical forms of these antibody mimics, in particular films and lithographic patterns, and their post‐functionalization from living chain‐ends. 相似文献
93.
Photo‐ and thermal‐polymerizations of 4‐diethoxyphosphoryl‐2,4,6‐tris(ethoxycarbonyl)‐1,6‐heptadiene, 4,4‐bis(diethoxyphosphoryl)‐2,6‐bis(t‐butoxycarbonyl)‐1,6‐heptadiene and 4‐diethoxyphosphoryl‐4‐ethoxycarbonyl‐2,6‐bis(t‐butoxycarbonyl)‐1,6‐heptadiene monomers and their phosphonic and carboxylic acid derivatives were investigated to understand the effect of the cyclic monomer structure on their polymerization reactivity. A strong effect of the substituents at positions 2, 4 and 6 of the monomers on polymerization rate was observed. The polymerizability of the monomers was successfully correlated with the 13C NMR chemical shifts of the vinyl carbons. Conversion values were consistent with the Tg being a measure of the flexibility of a monomer. The monomers containing phosphonic acid groups were soluble in water and ethanol. The acidic nature of the aqueous solutions of these monomers is expected to give them etching properties, important for dental applications. The interaction of the acid monomers with hydroxyapatite was investigated using 13C NMR technique.
94.
95.
Jessica Hao Ivana Stavljeni Milain Zeynep Batu Eken Marinka Mravak-Stipetic Kreimir Paveli Fusun Ozer 《Molecules (Basel, Switzerland)》2021,26(20)
Zeolites and zeolitic imidazolate frameworks (ZIFs) are widely studied as drug carrying nanoplatforms to enhance the specificity and efficacy of traditional anticancer drugs. At present, there is no other systematic review that assesses the potency of zeolites/ZIFs as anticancer drug carriers. Due to the porous nature and inherent pH-sensitive properties of zeolites/ZIFs, the compounds can entrap and selectively release anticancer drugs into the acidic tumor microenvironment. Therefore, it is valuable to provide a comprehensive overview of available evidence on the topic to identify the benefits of the compound as well as potential gaps in knowledge. The purpose of this study was to evaluate the potential therapeutic applications of zeolites/ZIFs as drug delivery systems delivering doxorubicin (DOX), 5-fluorouracil (5-FU), curcumin, cisplatin, and miR-34a. Following PRISMA guidelines, an exhaustive search of PubMed, Scopus, Embase, and Web of Science was conducted. No language or time limitations were used up to 25th August 2021. Only full text articles were selected that pertained to the usage of zeolites/ZIFs in delivering anticancer drugs. Initially, 1279 studies were identified, of which 572 duplicate records were excluded. After screening for the title, abstract, and full texts, 53 articles remained and were included in the qualitative synthesis. An Inter-Rater Reliability (IRR) test, which included a percent user agreement and reliability percent, was conducted for the 53 articles. The included studies suggest that anticancer drug-incorporated zeolites/ZIFs can be used as alternative treatment options to enhance the efficacy of cancer treatment by mitigating the drawbacks of drugs under conventional treatment. 相似文献
96.
Saracoglu S Soylak M Cabuk D Topalak Z Karagozlu Y 《Journal of AOAC International》2012,95(3):892-896
The determination of trace elements in food and soil samples by atomic absorption spectrometry was investigated. A coprecipitation procedure with holmium hydroxide was used for separation-preconcentration of trace elements. Trace amounts of copper(II), manganese(II), cobalt(II), nickel(ll), chromium(lll), iron(Ill), cadmium(ll), and lead(ll) ions were coprecipitated with holmium hydroxide in 2.0 M NaOH medium. The optimum conditions for the coprecipitation process were investigated for several commonly tested experimental parameters, such as amount of coprecipitant, effect of standing time, centrifugation rate and time, and sample volume. The precision, based on replicate analysis, was lower than 10% for the analytes. In order to verify the accuracy of the method, the certified reference materials BCR 141 R calcareous loam soil and CRM 025-050 soil were analyzed. The procedure was successfully applied for separation and preconcentration of the investigated ions in various food and soil samples. An amount of the solid samples was decomposed with 15 mL concentrated hydrochloric acid-concentrated nitric acid (3 + 1). The preconcentration procedure was then applied to the final solutions. The concentration of trace elements in samples was determined by atomic absorption spectrometry. 相似文献
97.
Zeynep Kurban Arthur Lovell Derek Jenkins Ian Loader Neal Skipper 《European Polymer Journal》2010,46(6):1194-1202
Homogenous turbostratic graphite nanofibres (TGNFs) have been synthesized by heat treatment of electrospun polyacrylonitrile in dimethylsulphoxide, offering a solution route of low toxicity to manufacture sub-60 nm diameter TGNFs. Characterization techniques including X-ray diffraction, scanning- and transmission electron microscopy have been used to study the graphitization process, and structural morphology of the nanofibres. The TGNFs have an entangled micro-fibril structure with turbostratic ordering of up to 40 graphene layers after heat treatment at 3000 °C. 相似文献
98.
Atilgan S Ekmekci Z Dogan AL Guc D Akkaya EU 《Chemical communications (Cambridge, England)》2006,(42):4398-4400
We introduce a novel class of water soluble, extended conjugation boradiazaindacene dyes which are efficient singlet oxygen generators and have spectacular photoinduced cytotoxicity when excited in the "therapeutic window" of the electromagnetic spectrum. 相似文献
99.
Muthukrishnan S Nitschke M Gramm S Ozyürek Z Voit B Werner C Müller AH 《Macromolecular bioscience》2006,6(8):658-666
[Image: see text] We report on the low-pressure plasma immobilization, characterization and application of thin films of hyperbranched glycoacrylates, poly(3-O-acryloyl-alpha,beta-D-glucopyranoside) (AGlc), on PTFE-like fluorocarbon surfaces. This method is an efficient and versatile way to immobilize sugar-carrying branched acrylates as thin films of approximately 5 nm thickness on polymeric substrates while the functional groups and properties of the immobilized molecules are largely retained. The extent of poly(AGlc) degradation during plasma immobilization was investigated using FTIR-ATR spectroscopy and XPS. The thickness and topography of the immobilized films were characterized using spectroscopic ellipsometry and SFM, respectively. Studies of protein adsorption, as well as cell adhesion and proliferation on the poly(AGlc) surfaces, showed that these materials are suitable for the control of biointerfacial phenomena. Fluorescence images of fibronectin adsorbed on to the branched glycoacrylate with a mask. 相似文献
100.
Zeynep Çiğdem Özcan 《International Journal of Mathematical Education in Science & Technology》2016,47(3):408-420
Studies highlight that using appropriate strategies during problem solving is important to improve problem-solving skills and draw attention to the fact that using these skills is an important part of students’ self-regulated learning ability. Studies on this matter view the self-regulated learning ability as key to improving problem-solving skills. The aim of this study is to investigate the relationship between mathematical problem-solving skills and the three dimensions of self-regulated learning (motivation, metacognition, and behaviour), and whether this relationship is of a predictive nature. The sample of this study consists of 323 students from two public secondary schools in Istanbul. In this study, the mathematics homework behaviour scale was administered to measure students’ homework behaviours. For metacognition measurements, the mathematics metacognition skills test for students was administered to measure offline mathematical metacognitive skills, and the metacognitive experience scale was used to measure the online mathematical metacognitive experience. The internal and external motivational scales used in the Programme for International Student Assessment (PISA) test were administered to measure motivation. A hierarchic regression analysis was conducted to determine the relationship between the dependent and independent variables in the study. Based on the findings, a model was formed in which 24% of the total variance in students’ mathematical problem-solving skills is explained by the three sub-dimensions of the self-regulated learning model: internal motivation (13%), willingness to do homework (7%), and post-problem retrospective metacognitive experience (4%). 相似文献