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101.
Vitaliy Datsyuk Milana Lisunova Maria Kasimir Svitlana Trotsenko Kati Gharagozloo-Hubmann Izabela Firkowska Stephanie Reich 《Applied Physics A: Materials Science & Processing》2011,105(4):781-788
We studied the thermal transport properties of multi-walled carbon nanotubes (MWNTs) in polymer and oil matrices. The thermal
conductivity of the oils and polymers increased linearly when adding tubes. We observe a particularly high increase in the
thermal diffusivity of carbon-nanotube-loaded liquid crystal polymers (6×10−5 cm2/s wt%), which is due to a spontaneous alignment of the MWNTs. Carbon nanotubes increased the thermal conductivity of oil
by a factor of three for 20 wt% loading. We found little or no dependence of the thermal enhancement on the specific flavor
of multiwall nanotubes used in the composites. Carbon nanotubes are excellent nanoscale fillers for composites in thermal
management application. 相似文献
102.
Izabela?Majchrzak-Kuc?baEmail author 《Journal of Thermal Analysis and Calorimetry》2012,107(3):911-921
The thermogravimetry (TG) was used for characterization of the fly ash (FA)-based MCM-41 mesoporous materials. MCM-41 mesoporous
materials were synthesized using silica extracts from different FA. The synthesis of MCM-41 from FA was carried out by the
hydrothermal method using the supernatants of coal FA (in the form of sodium silicate) and cationic cetyltrimethylammonium
bromide (CTAB) surfactants as the structure-directing agents. On the basis of the data obtained from the TG analysis, thermal
behaviour of FA-based MCM-41 mesoporous materials was assessed. This study has established the range of temperatures corresponding
to the desorption of water, decomposition of the surfactant and condensation of silanol, thereby making the overall quality
assessment of FA-based MCM-41 mesoporous materials. 相似文献
103.
Agnieszka Adamczyk-Woźniak Michał K. Cyrański Beata T. Frączak Agnieszka Lewandowska Izabela D. Madura Andrzej Sporzyński 《Tetrahedron》2012,68(19):3761-3767
ortho-Iminomethylphenylboronic acids were synthesized from the reaction of 2-formyl–phenylboronic acid with primary aromatic amines. Reduction of these compounds yielded the corresponding aminomethylphenylboronic acids. For both types of the compounds, the crystal structure was determined by single crystal X-ray diffraction method. Hydrogen-bonded dimers with an additional intramolecular B–O–H…N hydrogen bond have been observed. Calculations at MP2/6–31+G** level proved that the most stable form is that with the above-mentioned intramolecular hydrogen bond while the form with dative N→B bond is less favoured. Since the calculated energy difference is small, the competition between possible forms was analyzed in terms of substituent effect stabilization energy (SESE). In the case of p-iminomethylphenylboronic acid, both hydroxyl groups are engaged in intermolecular O–H…O interactions resulting in a supramolecular ribbon motif. 相似文献
104.
Agnieszka Maruszewska Wojciech wiereo Marta Skrka-Majewicz Irena Baranowska-Bosiacka Agata Wszoek Katarzyna Janda Daria Kulis Patrycja Kapczuk Dariusz Chlubek Izabela Gutowska 《Molecules (Basel, Switzerland)》2021,26(14)
Breast milk has the most suitable composition for the proper development in the first year of a child’s life. However, it is often replaced with artificial milk. The aim of the study was to analyze the composition of essential elements: Na, K, Ca, P, Mg, Fe, Zn, Cu, and Mn as well as toxic elements: Ni, Pb, Sr, Li, and In in 18 formulas available in Poland. The daily supply was also estimated. The study was performed by Inductively Coupled Plasma Optical Emission Spectrometry method. The results showed the presence of all essential elements tested, but the content of P and Mn significantly differed from the concentrations declared. Such discrepancies can have significant impact on the daily dose of the bioelements taken. However, the content of elements was within the reference standards established by the EU Directive with exception of P, the amount of which exceeded the norms 5.23–18.80-times. Daily supply of P in tested milk as well as Fe and Mn provided with first and hypoallergenic formula exceeded the adequate intake. Analysis revealed the contamination with harmful elements—Pb, Sr, Li, and In were detected in almost all products. The study confirms the data concerning some discrepancies in composition and the contamination of food and may provide information on the feeding quality of children and estimation of health risk associated with exposure to toxic elements. 相似文献
105.
Polybrominated diphenyl ethers (PBDEs) are a group of persistent organic pollutants. They are used as flame retardants in plastics, paints, varnishes and textile materials. PBDEs pose great risk to the environment because of their high persistence and ability to get into the environment easily due to the lack of chemical bonds with the matrix of materials, to which they are added. Global research studies confirmed the occurrence of those compounds in the majority of elements of water and land environment. Analysis of PBDEs in environmental samples is one of the specific analytical methods of criteria that comprise low detection limits and high selectivity. The analysis of PBDEs in environmental samples is one of the specific analytical methods, in which the main criteria are low detection limits and high selectivity. In this article, a literature review of methods for environmental sample preparation and analysis of the PBDE content was presented. The article discusses the potential of modern extraction techniques such as: solid-phase microextraction, single-drop microextraction, dispersive liquid-liquid microextraction, microwave-assisted extraction, cloud point extraction, hollow fibre-liquid phase microextraction and others for the separation of PBDEs from environmental samples with a complex matrix. Among the methods for qualitative and quantitative determination of PBDEs, a particular focus was put on gas chromatography/mass spectrometry with various injection techniques and different types of sample ionisation. 相似文献
106.
Izabela Agata Malinowska 《Acta Mathematica Hungarica》2012,136(1-2):76-89
A number of authors have studied the structure of a finite group G under the assumption that some subgroups of?G are well located in?G. We will generalize the notion of s-permutable and s-permutably embedded subgroups and we will obtain new criterions of p-nilpotency and supersolvability of groups. We also generalize some known results. 相似文献
107.
Kapturowska AU Stolarzewicz IA Krzyczkowska J Białecka-Florjańczyk E 《Ultrasonics sonochemistry》2012,19(1):186-191
The aim of this study was to evaluate the efficiency of sonication in releasing protein from a widespread lipase-producing yeast, Yarrowia lipolytica KKP 379, and to examine the impact of ultrasound waves generated in a horn-type sonicator on the lipolytic activity of Y. lipolytica in the hydrolysis of p-nitrophenyl laurate. In this paper, we focused on a few parameters of ultrasound cell disruption, such as the time of sonication, acoustic power, storage time of the frozen yeast biomass used in sonication and the solvent used to suspend the yeast cells which were considered as the most important part in the process of obtaining a biocatalyst from Y. lipolytica for organic synthesis. The most effective additive in protein release proved to be 2% Tween 80; other ideal parameters of the process were ultrasonic power at 150 W for 15 min and 9 weeks of frozen biomass storage time. The sonication parameters, which were the best for protein release, did not seem to be the most effective for obtaining high lipolytic activity due to denaturation as an effect of cavitation. 相似文献
108.
Janusz Zachara Izabela Madura Marek Wostowski 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(1):o57-o59
Two structural isomers, 3,6‐bis(2‐chlorophenyl)‐1,4‐dihydro‐1,2,4,5‐tetrazine, (I), and 3,5‐bis(2‐chlorophenyl)‐4‐amino‐1H‐1,2,4‐triazole, (II), both C14H10Cl2N4, form chain‐like structures in the solid state, stabilized by N—H⋯N and N—H⋯Cl hydrogen bonds. A contribution from weak interactions to the strong hydrogen‐bond network is observed in both structures. The secondary graph sets for intermolecular hydrogen bonds [(11) for (I) and (12) for (II)] indicate the similarity between the networks. 相似文献
109.
110.
Viktor Jobbágy Izabela Chmielewska Tibor Kovács Stanislaw Cha?upnik 《Microchemical Journal》2009,93(2):200-205
Due to the importance of water in human life, its quality must be strictly controlled; so simple and reliable analytical methods must be available. For this purpose a rapid procedure for the determination of uranium isotopes in natural water samples with elevated salinity was adopted. It was tested in 16 water samples from Upper and Lower Silesia Regions in Poland. Water samples had salinity in a range of 290–26,925 mg l− 1.In water samples the concentrations of 234U and 238U ranged from 2.07 to 52.08 mBq l– 1 and from 2.18 to 43.38 mBq l– 1 respectively, while 235U level was below MDA (0.7 mBq l− 1).The isotopic ratio of 234U/238U varies in the range from 0.949 to 3.344 in all investigated waters which means that there is usually no radioactive equilibrium between the parent nuclide 238U and its daughter product 234U.These results do not show a correlation between total dissolved solids (TDS) values and concentration of dissolved uranium isotopes.Committed effective dose for adults due to uranium intake as a result of drinking water usage was in range of 0.15–3.29 µSv y− 1 with an average value of 1.09 µSv y− 1 far below the 100 µSv y− 1 WHO recommendation. 相似文献