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111.
Lipid nanoparticles based on multiple emulsion (W/O/W) systems are suitable for incorporating hydrophilic active substances, including iridoid glycosides. This study involved optimization of composition of lipid nanoparticles, incorporation of active compounds (aucubin and catalpol), evaluation of stability of the resulting nanocarriers, and characterization of their lipid matrix. Based on 32 factorial design, an optimized dispersion of lipid nanoparticles (solid lipid:surfactant—4.5:1.0 wt.%) was developed, predisposed for the incorporation of iridoid glycosides by emulsification-sonication method. The encapsulation efficiency of the active substances was determined at nearly 90% (aucubin) and 77% (catalpol). Regarding the stability study, room temperature was found to be the most suitable for maintaining the expected physicochemical parameter values (particle size < 100 nm; polydispersity index < 0.3; zeta potential > |± 30 mV|). Characterization of the lipid matrix confirmed the nanometer size range of the resulting carriers (below 100 nm), as well as the presence of the lipid in the stable β’ form. 相似文献
112.
Szydłowska I Nosenko Y Brutschy B Tarakeshwar P Herbich J 《Physical chemistry chemical physics : PCCP》2007,9(36):4981-4991
We present the results of spectroscopic and photophysical investigations of 4-diethylaminopyridine (DEAP) and its 1 : 1 complexes with a number of protic solvents such as water and various alcohols of different acidity isolated under supersonic jet conditions. While a double resonance vibrational spectroscopic method was employed to investigate the size and geometrical structure of jet-cooled clusters, laser-induced fluorescence spectroscopy was used to examine the changes of photophysics induced by complexation of DEAP with solvent molecule(s). The results obtained from ab initio calculations enable the assignment of geometries and of the vibrational spectra of the clusters in the OH-stretch region. The comparison of the experimental and calculated vibrational spectra indicates that the solvent molecule is hydrogen-bonded to the pyridine nitrogen atom. Dual luminescence is observed only for the complexes with alcohols of relatively strong acidity. 相似文献
113.
Izabela Janowska Kambiz Chizari Jean-Hubert Olivier Raymond Ziessel Marc Jacques Ledoux Cuong Pham-Huu 《Comptes Rendus Chimie》2011,14(7-8):663-670
Palladium supported on vertically aligned multi-walled carbon nanotubes (Pd/VA-CNTs) is used as catalyst for the C-C coupling reactions of p-iodonitrobenzene with styrene and ethyl acrylate under microwaves irradiation. Pd/VA-CNTs catalyst exhibits higher activity compared to Pd supported on activated charcoal, under the same reaction conditions. Due to the microwaves irradiation, the kinetics of the reaction is strongly accelerated compared to that obtained with a traditional heating mode. The macroscopic form of aligned CNTs support allows an easy recovery of the catalyst, avoiding a costly post-reaction filtration. In addition, the interaction between the active phase and the support leads to the negligible leaching of palladium during recycling tests. The observed results indicate that Pd/CNTs is a recyclable and stable heterogeneous catalytic system. 相似文献
114.
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
115.
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
116.
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
117.
Abstract Oxygen contamination is the main source of free electrons in bulk GaN grown at high-pressure. We used erbium as a promising getter/compensation center to reduce the electron content in GaN. Both optical and electrical measurements indicate the reduction of electron concentration from the initial 6 × 1019cm?3 down to 1 × 1019cm?3. A photoluminescence study proves that erbium is incorporated into the GaN host lattice, and emits light at ~ 1.5μm. 相似文献
118.
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
119.
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
120.
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