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511.
Emilia Miszczyk Przemysław Morawiak Rafał Mazur Mateusz Mrukiewicz Marek Olifierczuk Wiktor Piecek 《Liquid crystals》2018,45(5):703-714
We developed an interference method for determination refractive indices of nematic liquid crystals in a broad electromagnetic spectrum. Values of ordinary and extraordinary refractive indices were measured in VIS (from 0.4 to 0.8 μm), NIR (from 0.8 to 1.4 μm), SWIR (from 1.4 to 3.0 μm) and at an edge of MWIR (from 3.0 to 4.2 μm) regions. The main task of this work was to develop the efficient and accurate interference method. The absolute error of these measurements is not higher than 0.02. The method was tested on two newly designed mixtures. The first one was a high birefringence liquid crystal mixture for the laser rangefinder, while the second one is intentionally prepared for breathalyser application. The mixture does not possess high absorption bands at 3.4 μm. To measure a dispersion of the refractive indices cells with various thicknesses and dielectric mirrors were prepared. The paper presents a theoretical discussion and experimental results. 相似文献
512.
Sherif Ashraf Fahmy Fortuna Ponte Iten M. Fawzy Emilia Sicilia Udo Bakowsky Hassan Mohamed El-Said Azzazy 《Molecules (Basel, Switzerland)》2020,25(24)
P-sulfonatocalix[n]arenes have demonstrated a great potential for encapsulation of therapeutic drugs via host-guest complexation to improve solubility, stability, and bioavailability of encapsulated drugs. In this work, guest-host complexes of a third-generation anticancer drug (oxaliplatin) and p-4-sulfocalix[n]arenes (n = 4 and 6; p-SC4 and p-SC6, respectively) were prepared and investigated, using 1H NMR, UV, Job’s plot analysis, and DFT calculations, for use as cancer therapeutics. The peak amplitude of the prepared host-guest complexes was linearly proportional to the concentration of oxaliplatin in the range of 1.0 × 10−5 M−1 to 2.1 × 10−4 M−1. The reaction stoichiometry between either p-SC4 or p-SC6 and oxaliplatin in the formed complexes was 1:1. The stability constants for the complexes were 5.07 × 104 M−1 and 6.3 × 104 M−1. These correspond to complexation free energy of −6.39 and −6.52 kcal/mol for p-SC4 and p-SC6, respectively. Complexation between oxaliplatin and p-SC4 or p-SC6 was found to involve hydrogen bonds. Both complexes exhibited enhanced biological and high cytotoxic activities against HT-29 colorectal cells and MCF-7 breast adenocarcinoma compared to free oxaliplatin, which warrants further investigation for cancer therapy. 相似文献
513.
ukasz opusiewicz Emilia Drozowska Paulina Trocer Pawe Kwiatkowski Artur Bartkowiak Annett Gefrom Monika Sienkiewicz 《Molecules (Basel, Switzerland)》2020,25(24)
Plant derived fermented beverages have recently gained consumers’ interest, particularly due to their intrinsic functional properties and presence of beneficial microorganisms. Three variants containing 5%, 10%, and 15% (w/w) of sweet blue lupin (Lupinus angustifolius L. cv. “Boregine”) seeds were inoculated with kefir grains and incubated at 25 °C for 24 h. After processing, beverages were stored in refrigerated conditions (6 °C) for 21 days. Changes in microbial population, pH, bioactive compounds (polyphenolics, flavonoids, ascorbic acid), reducing sugars, and free amino acids were estimated. Additionally, viscosity, firmness, color, and free radicals scavenging properties were determined. Results showed that lactic acid bacteria as well as yeast were capable of growing well in the lupin matrix without any supplementation. During the process of refrigeration, the viability of the microorganisms was over the recommended minimum level for kefir products. Hydrolysis of polysaccharides as well as increase of free amino acids was observed. As a result of fermentation, the beverages showed excellent DPPH, ABTS+·, ·OH, and O2− radicals scavenging activities with a potential when considering diseases associated with oxidative stress. This beverages could be used as a new, non-dairy vehicle for beneficial microflora consumption, especially by vegans and lactose-intolerant consumers. 相似文献
514.
Improved biosensors for acetaldehyde determination have been developed using a bienzymatic strategy, based on a mediator-modified carbon film electrode and co-immobilisation of NADH oxidase and aldehyde dehydrogenase. Modification of the carbon film electrode with poly(neutral red) mediator resulted in a sensitive, low-cost and reliable NADH detector. Immobilisation of the enzymes was performed using encapsulation in a sol-gel matrix or cross-linking with glutaraldehyde. The bienzymatic biosensors were characterized by studying the influence of pH, applied potential and co-factors. The sol-gel and glutaraldehyde biosensors showed a linear response up to 60 μM and 100 μM, respectively, with detection limits of 2.6 μM and 3.3 μM and sensitivities were 1.7 μA mM−1 and 5.6 μA mM−1. The optimised biosensors showed good stability and good selectivity and have been tested for application for the determination of acetaldehyde in natural samples such as wine. 相似文献
515.
García-Ruiz S Petrov I Vassileva E Quétel CR 《Analytical and bioanalytical chemistry》2011,401(9):2785-2792
The cadmium content in surface water is regulated by the last European Water Framework Directive to a maximum between 0.08
and 0.25 μg L−1 depending on the water type and hardness. Direct measurement of cadmium at this low level is not straightforward in real
samples, and we hereby propose a validated method capable of addressing cadmium content below μg L−1 level in natural water. It is based on solid-phase extraction using TiO2 nanoparticles as solid sorbent (0.05 g packed in mini-columns) to allow the separation and preconcentration of cadmium from
the sample, combined to direct isotope dilution and detection by inductively coupled plasma mass spectrometry (ID-ICP-MS).
The extraction setup is miniaturised and semi-automated to reduce risks of sample contamination and improve reproducibility.
Procedural blanks for the whole measurement process were 5.3 ± 2.8 ng kg−1 (1 s) for 50 g of ultrapure water preconcentrated ten times. Experimental conditions influencing the separation (including
loading pH, sample flow rates, and acid concentration in the eluent) were evaluated. With isotope dilution the Cd recovery
rate does not have to be evaluated carefully. Moreover, the mathematical model associated to IDMS is known, and provides transparency
for the uncertainty propagation. Our validation protocol was in agreement with guidelines of the ISO/IEC 17025 standard (chapter
5.4.5). Firstly, we assessed the experimental factors influencing the final result. Secondly, we compared the isotope ratios
measured after our separation procedure to the reference values obtained with a different protocol for the digested test material
IMEP-111 (mineral feed). Thirdly, we analysed the certified reference material BCR-609 (groundwater). Finally, combined uncertainties
associated to our results were estimated according to ISO-GUM guidelines (typically, 3–4% k = 2 for a cadmium content of around 100 ng kg−1). We applied the developed method to the groundwater and wastewater samples ERM-CA615 and BCR-713, respectively, and results
agreed with certificate values within uncertainty statements. 相似文献
516.
Mancini E De Martino L Marandino A Scognamiglio MR De Feo V 《Molecules (Basel, Switzerland)》2011,16(9):7725-7735
The chemical composition of the essential oil of Helichrysum italicum (Roth) Don ssp. italicum, collected in the National Park of Cilento and Diano Valley, Southern Italy, was studied by means of GC and GC/MS. Forty four compounds of 45 constituents were identified in the oil, mainly oxygenated sesquiterpenes. The essential oil was evaluated for its potential in vitro phytotoxic activity against germination and early radicle elongation of radish and garden cress. The radicle elongation of radish was significantly inhibited at the highest doses tested, while germination of both seeds was not affected. 相似文献
517.
Emilia D. Naydenova Petar T. Todorov Kolio D. Troev 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1315-1320
A series of new cycloalkanespiro-5-hydantoin phosphonic acids have been synthesized and characterized. The mixture of [(2,4-dioxo-1,3-diazaspiro-alkane-3-yl)-methyl]phosphonic acids and [(2,4-dioxo-1,3-diazaspiro-alkane-1,3-diyl)dimethyl]diphospho-nic acids was obtained from cycloalkanespiro-5-hydantoins, formaldehyde, and phosphorus trichloride in a molar ratio of 1:2:2, by a procedure modified by us. Their structures were proved by means of IR, 1H, 13C{1H} and 31P NMR spectroscopy. 相似文献
518.
Saadi Bayat Bimo A. Tejo Emilia Abdulmalek Normi Mohd Yahya Abu Bakar Salleh 《合成通讯》2013,43(20):2725-2732
This work reports the effectiveness of short polar peptides as asymmetric catalysts in Michael reactions to attain good yields of enantio- and diastereoselective isomers. In a comparison, glutamic acid and histidine produced greater ee and yields when they were applied as the second amino acid in short trimeric peptides. These short polar peptides were found to be efficient organocatalysts for the asymmetric Michael addition reaction in water.
Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献
519.
The complexation of several local anaesthetics by β and γ-cyclodextrins was studied by potentiometry with glass electrode. Tetracaine and dibucaine complexation constants were determined at 25°C in the presence of 0.1 M of NaCl. It was found that prilocaine and lidocaine complexes cannot be detected. 相似文献
520.
Casolaro M Del Bello B Barbara del B Maellaro E Emilia M 《Colloids and surfaces. B, Biointerfaces》2011,88(1):389-395
Two acrylic hydrogels, of low cross-linking content and carrying the L-valine residues, were synthesized and studied as a platform to load and release the chemotherapeutic agent cisplatin. The platinum(II)-complex species showed a well-defined stoichiometric ratio in which two carboxylate groups of the collapsing gel coordinate a metal center; this was confirmed by FT-IR spectra. When loaded in water, a zero-order release rate of platinum(II)-species was shown in the physiologic solution (PBS, pH 7.40) for more than one week. Moreover, the amount of platinum(II)-species released from the hydrogel may be improved either by the cross-linking degree and by the temperature. Any increase of the cross-links results in a decreased slope of the straightline Pt(II)/gel (mg/g) versus time, whereas the increasing temperature results in a greater amount of platinum(II)-species in solution. The chemical- and swelling-controlled release are the main mechanisms supervising the whole release process. On the other hand, the loading of cisplatin and temsirolimus in DMF showed a characteristic two phase releasing pattern; the initial burst effect was always followed by the zero-order release rate for a week. In this case only a swelling-controlled mechanism was mainly invoked. The cytotoxic activity towards Me665/2/21 human melanoma cell line, afforded by the cisplatin-loaded hydrogel, was close and in some cases higher compared to the native cisplatin at the same concentration; an interesting synergy in term of cytotoxicity was observed when a combined treatment of temsirolimus and cisplatin was used, although temsirolimus exerted only a moderate inhibition of cell proliferation. 相似文献