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121.
Grzegorz Lota Krzysztof Fic Krzysztof Jurewicz Elzbieta Frackowiak 《Central European Journal of Chemistry》2011,9(1):20-24
Electrochemical storage of hydrogen in activated carbon material has been investigated using different parameters of cathodic
polarization. It has been proven that application of short galvanostatic pulses could be efficient for hydrogen storage in
microporous carbon material. Charging current loads from 50 mA g−1 to 32 A g−1 have been used showing correlation between hydrogen capacity, time of charging and electrical efficiency. The anodic charge
equivalent to electrooxidation of 1.0 wt% of hydrogen can be already reached after 90 s of cathodic polarization. Temperature
effect has been also evaluated and a gradual increase of hydrogen capacity with a better pronounced oxidation plateau was
obtained at higher temperatures. Reversible electrosorption of hydrogen is a useful reaction in supercapacitor performance
and it might have a potential application for a negative electrode of supercapacitor as well as reversibly operating electrode
in the secondary cell.
相似文献
122.
David Aebisher Jan Cichonski Ewa Szpyrka Sygit Masjonis Grzegorz Chrzanowski 《Molecules (Basel, Switzerland)》2021,26(13)
Oxidative stress has been reported as a cause of many diseases like Parkinson′s, Alzheimer′s, cardiovascular disease, and diabetes. Oxidative stress can also lead to cancer formation by promoting tumor development and progression. Antioxidants derived from Lamiaceae plants play an important role in natural medicine, pharmacology, cosmetology, and aromatherapy. Herein, we examine the antioxidative capacity of essential oils from seven aromatic Lamiaceae plants against the synthetic radicals DPPH and ABTS. Among the essential oils analyzed, the most robust scavenging capacities were found in mixtures of volatile compounds from thyme and savory. The scavenging activity of tested EOs against the ABTS radical was clearly higher than activity towards DPPH. Analysis of essential oils with weaker antioxidant activity has shown that volatile compounds from marjoram, sage, and hyssop were more active than EOs from lavender and mint. It can be suggested that the potent antioxidant capacity of thyme (Thymus vulgaris) and savory (Satyreja hortensis) are related to a high level of phenolic constituents, such as thymol and carvacrol. On the other hand, the elevated antioxidative power of marjoram, sage, and hyssop essential oils may also be due to their terpinene, o-cymene, terpinolene, and terpinen-4-ol constituents. Although non-phenolic components are less active than thymol or carvacrol, they may affect antioxidant capacity synergistically. 相似文献
123.
Małgorzata Norek Grzegorz Łuka Marek Godlewski Tomasz Płociński Marta Michalska-Domańska Wojciech J. Stępniowski 《Applied Physics A: Materials Science & Processing》2013,111(1):265-271
Luminescent properties of ZnO nanorods covered with Ag nanoparticles are examined. Nanorods were synthesized on AAO templates using Atomic Layer Deposition (ALD) technique. Two types of the samples were prepared with different arrangement of ZnO nanorods and doping conditions. Nanorods of the second type were codoped with Al, to stimulate defect-related emissions. The ZnO material fills heterogeneously the interior of the AAO nanopores and has hexagonal, wurtzite structure. Both types of structures exhibit a broad defect-related emission at about 440 nm, most probably related to recombination at zinc interstitial (Zni) defects. This emission in samples with a random distribution of ZnO:Al nanorods and finer Ag nanoparticles is enhanced by factor of ~2.5 upon Ag deposition. The so-obtained material is interesting from the point of view of its application in blue range emitting diodes. 相似文献
124.
The main objective of our work was to investigate the possibility and usefulness of indirect methods in X-ray microanalysis
for the quantification of biologically important compounds. Metallothionein-like proteins (MT-like proteins) from kidney and
liver, rich in sulfur were chosen as an indicator of heavy metal presence in cells and their environment. Tissues from goldfish
(Carassius auratus gibelio) were sampled after short and prolonged periods of exposure to Co+2, CrO4
−2, Pb+2, Cu+2 and control treatment and prepared for histochemical staining for peroxidated thiolate groups. Commonly used –S–S– bonds
dye (Nitro Red) was replaced with iodine atoms and they were quantified at L line by means of X-ray microanalysis combined
with SEM. After fish treatments with heavy metal solutions changes in MT-like proteins and in I atom contents were expected.
There was statistically significant decrease in MT-like proteins level in kidney after lead treatment (Pb/C = 0.62). In liver
a statistically significant increase in MT-like proteins concentration was observed after chromium, cobalt and lead ions treatment
in comparison to control animals. The following ratios were noted: 3.04 for Cr/C, 2.18 for Co/C and 2.10 for Pb/C. Our finding
indicates that the method of indirect measurement of MT-like proteins in fish and other animal tissues is possible. The concentration
of iodine atoms is above their detection level by EDS and their changes are possible to identify. During histochemical procedures
it is worth taking into account sample preparation methods which might disturb the quality and quantity of the analysed material. 相似文献
125.
Grzegorz Bejcar Piotr Przybylski Joanna Fusiara Bogumil Brzezinski Franz Bartl 《Journal of Molecular Structure》2005,754(1-3):31-36
A new hydrazone of gossypol with 3,6-dioxaheptylhydrazine (GHDO) has been synthesised and its structure has been studied by FT-IR, 1H NMR, 13C NMR as well as PM5 semiempirical methods. All the studies have provided clear evidence of the existence of GHDO in the solution in the N-imine–N-imine tautomeric form. The structure and the spectroscopic behaviour of this tautomer are discussed in details. It is shown the structure of GHDO is strongly stabilised by different types of intramolecular hydrogen bonds. In two of them the oxygen atoms of the oxaalkyl chains are also engaged. The strongest intramolecular hydrogen bond is formed between the O7H proton and N16 atom from the hydrazone group. 相似文献
126.
Elastic deformations of homeotropic nematic liquid crystal layers subjected to a d.c. electric field were studied numerically in order to find the dependence of threshold voltage on the properties of such a system. A nematic material characterized by a negative sum of flexoelectric coefficients and by a small negative dielectric anisotropy was considered. The flow of ionic current was taken into account. The electric properties are described in terms of a weak electrolyte model. Finite surface anchoring strength was assumed. The director orientation, the electric potential and the ion concentrations were calculated as functions of the coordinate normal to the layer. It was found that the threshold for the deformation depends on the distributions of the ions, governed by the generation constant and by the properties of the electrodes. The effects observed may be interpreted as a consequence of the separation of the ions. When the electrodes have pronounced blocking character, a high and non-uniform electric field, created by the subelectrode ion space charges, causes drastic decrease of the threshold voltage, much below the value U f valid for the insulating nematic. On the other hand, the electric field gradient arising in the bulk at moderate concentrations has a stabilizing effect and remarkably enhances the threshold above U f. When the electrodes are conducting there are no significant space charges and the threshold voltage remains close to U f. These results indicate that phenomena related to the charge transport should be taken into account in the analysis of the elastic deformations of ion-containing flexoelectric nematics. 相似文献
127.
128.
Grzegorz ukaszewicz 《Mathematical Methods in the Applied Sciences》1988,10(3):329-337
We consider a boundary-value problem describing the motion of viscous, incompressible and heat-conducting fluids in a bounded domain in ?3. We admit non-homogeneous boundary conditions, the appearance of exterior forces and heat sources. Our aim is to prove the existence of a solution of the problem in Sobolev spaces. 相似文献
129.
Summary The representative refined mineral oil samples, crude petroleum straightrun distillates, potentially used in the manufacture of crop protection products were analysed by isocratic and gradient high performance liquid chromatography (HPLC) to investigate their trace polycyclic aromatic hydrocarbon (PAH) content. Liquid-liquid extraction followed by size-exclusion column chromatography was employed to isolate the fraction containing PAHs with more than two fused rings. The identity of individual PAHs was confirmed by comparing their UV and fluorimetric detector signals with those recorded from reference standards. The level of extracted PAHs in the oil samples are discussed with respect to their physical and chemical properties. 相似文献
130.
Grzegorz Michalski 《Mathematical Logic Quarterly》1992,38(1):203-208
Let Γn(φ) be a formula of LPA (PA = Peano Arithmetic) meaning “there is a proof of φ from PA-axioms, in which ω-rule is iterated no more than n times”. We examine relations over pairs of natural numbers of the kind. (n, k) ≦H (n', k') iff PA + RFNn' (Hk') ? RFNn (Hk). Where H denotes one of the hierarchies ∑ or Π and RFNn(C) is the scheme of the reflection principle for Γn restricted to formulas from the class C(Γn(φ) implies “φ is true”, for every φ ∈ C). Our main result is that. (n, k) ≦H (n', k') if n ≦ n' and k ≦ max (k', 2n' + 1). 相似文献