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In the paper methods of the terahertz photomixer operational frequency estimation are considered. Three methods are investigated — estimation of the frequency via direct measurements of the laser heterodyne compounds, via calculations from datasheets, and via calculations from raw collected data obtained from the photomixer system. 相似文献
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Dominika Teklinska Kinga Kosciewicz Kacper Grodecki Mateusz Tokarczyk Grzegorz Kowalski Wlodzimierz Strupinski Andrzej Olszyna Jacek Baranowski 《Central European Journal of Physics》2011,9(2):446-453
Polytype instability of SiC epitaxial films was the main focus of attention in the experiment performed since this factor
has a decisive influence on graphene growth, which was the second stage of the experiment. Layers deposited in various initial
C/Si ratios were analyzed. 相似文献
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Dr. Aleksandra Mielewczyk-Gryń Dr. Sebastian Wachowski Dr. Kacper Dzierzgowski Iga Szpunar Dr. Judyta Strychalska-Nowak Prof. Tomasz Klimczuk Dr. Mirosław Sawczak Prof. Maria Gazda 《Chemphyschem》2023,24(1):e202200368
LaNb0.8M0.2O4-δ (where M=As, Sb, V, and Ta) oxides with pentavalent elements of different ionic sizes were synthesized by a solid-state reaction method. The vibrational properties of these oxides have been investigated. These studies revealed that the substituent element influences both Debye temperature value as well as the Raman active vibrational modes. Additionally, the low-temperature vibrational properties of LaNb0.8Sb0.2O4-δ have been determined to show the phase transition occurrence at 260 K which is lower than previously reported. 相似文献
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Amanda Grylewicz Kacper Szymaski Dominika Darowna Sylwia Mozia 《Molecules (Basel, Switzerland)》2021,26(9)
Ultrafiltration polyethersulfone (PES) membranes were prepared by wet phase inversion. Commercial halloysite nanotubes (HNTs) in the quantities of 0.5 wt% vs. PES (15 wt%) were introduced into the casting solution containing the polymer and different solvents: N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), or 1-methyl-2-pyrrolidinone (NMP). The type of solvent influenced the membranes’ morphology and topography, as well as permeability, separation characteristics, and antifouling and antibacterial properties. The membranes prepared using DMA exhibited the loosest cross-section structure with the thinnest skin and the roughest surface, while the densest and smoothest were the DMF-based membranes. The advanced contact angles were visibly lower in the case of the membranes prepared using DMF compared to the other solvents. The highest water permeability was observed for the DMA-based membranes, however, the most significant effect of the modification with HNTs was found for the NMP-based series. Regardless of the solvent, the introduction of HNTs resulted in an improvement of the separation properties of membranes. A noticeable enhancement of antifouling performance upon application of HNTs was found only in the case of DMF-based membranes. The study of the antibacterial properties showed that the increase in surface roughness had a positive effect on the inhibition of E. coli growth. 相似文献
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Mielewczyk-Gryń Aleksandra Wachowski Sebastian Prześniak-Welenc Marta Dzierzgowski Kacper Regoutz Anna Payne David J. Gazda Maria 《Journal of Thermal Analysis and Calorimetry》2019,138(1):225-232
In this work, lanthanum orthoniobates doped with either antimony, calcium, or both have been synthesized and studied. The water uptake of the investigated materials has been analyzed by means of thermogravimetric studies. The results show the difference between the thermodynamics of hydration between the lanthanum orthoniobate system and other proton conducting ceramics. The relation between the water uptake and effective acceptor doping for the investigated system has been found, and the energetics of the water uptake relation are discussed.
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The result ƒB≈ƒD which had been obtained from sum rules and lattice calculations, and which contradicts the naïve prediction ƒp1/√Mp, is rederived using a simple argument based on semilocal parton-hadron duality. Is is argued that both here and in sum rules the key point is the use of semilocal duality instead of the bound-state wave functions. 相似文献
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Competition between Nucleophilic Substitution of Halogen (SNAr) versus Substitution of Hydrogen (SNArH)—A Mass Spectrometry and Computational Study 下载免费PDF全文
Kacper Błaziak Prof. Mieczysław Mąkosza Prof. Witold Danikiewicz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(16):6048-6051
The mechanism of intramolecular gas‐phase reactions of N‐(2‐X‐5‐nitrophenyl)‐N‐methylacetamide carbanions (X=H, F, Cl) has been studied using negative ion electrospray mass spectrometry ((?)ESI‐MS) technique and modelled computationally. It was proven that all three anions form cyclic σH adducts, which undergo elimination of water. In the case of X=F, formation of the σF adduct, leading to SNAr reaction, was a competing process. This is the first proof that also in the gas phase formation of σH adduct proceeds faster than σX adduct and only when X=F, rates of these two processes are comparable. The experimental results are in full agreement with quantum chemical calculations. 相似文献
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Kacper Kopczyński Daria Pęziak-Kowalska Katarzyna Lota Tomasz Buchwald Anna Parus Grzegorz Lota 《Journal of Solid State Electrochemistry》2017,21(4):1079-1088
The activated carbon was modified by the wet method with a solution of ammonium persulfate at room temperature with different times. Kinetics studies showed that the modification took place mostly during the first 60 min of the process. The physicochemical properties of the obtained carbon were evaluated by thermogravimetric studies, Raman and FTIR spectroscopy, elementary and BET analyses. Furthermore, the fabricated material was applied in symmetric capacitors operated on the three aqueous electrolytes (1 M H2SO4, 6 M KOH and 1 M Na2SO4). Mild conditions of the modification process are optimal to obtain electroactive groups on the carbon surface, which make this material useful in a supercapacitor application. In our studies, we noticed that this type of functional groups mainly appears on the surface of the activated carbon, in the first oxidation stage. With prolonged oxidation, they may transform into undesirable groups. The results show that this kind of modification improves the capacity of all the tested supercapacitors. It was connected mainly with an increase of the carbon material’s wettability and in the case of capacitor operated in acid and base electrolytes due to a redox reaction of oxygen functional groups. 相似文献