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Dressing process in the grinding of aerospace blade root
Łukasz Żyłka,Robert Babiarz 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.9
This study investigates the grinding wheel dressing process in the grinding of aerospace blade root fir tree profile made from Inconel 718 alloy. This work primarily aims to determine the influence of dressing process parameters on the grinding process and the quality of the grinded surface with the use of a profile roller. The grinding of the blade root surface was tested using different settings of the dressing process. Grinding force components and vibration amplitude were recorded, and the grinded surface roughness was measured after each test. The most important finding of the study was the determination of the relationship of dressing speed ratio, dressing feed, the components of the grinding force, and the grinded surface roughness. Based on the identified relationships in the dressing process, the appropriate values of dressing parameters can be selected to obtain the required quality of the grinded surface of the root.
Concrete compressive strength prediction using the imperialist competitive algorithm
Łukasz Sadowski,Mehdi Nikoo,Mohammad Nikoo 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.22 No.4
In the following paper, a socio-political heuristic search approach, named the imperialist competitive algorithm (ICA) has been used to improve the efficiency of the multi-layer perceptron artificial neural network (ANN) for predicting the compressive strength of concrete. 173 concrete samples have been investigated. For this purpose the values of slump flow, the weight of aggregate and cement, the maximum size of aggregate and the water-cement ratio have been used as the inputs. The compressive strength of concrete has been used as the output in the hybrid ICA-ANN model. Results have been compared with the multiple-linear regression model (MLR), the genetic algorithm (GA) and particle swarm optimization (PSO). The results indicate the superiority and high accuracy of the hybrid ICA-ANN model in predicting the compressive strength of concrete when compared to the other methods.
Taxonomic review of the tribe Syntomini (Lepidoptera: Erebidae: Arctiinae) in Korea
Łukasz Przybyłowicz,Witold Morek,Bong-Kyu Byun 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.3
Molecular characterization of a venomacid phosphatase from the Asiatic honeybee Apis cerana
Synthesis and in vitro antimicrobial activity screening of new pipemidic acid derivatives
Łukasz Popiołek,Anna Biernasiuk,Kinga Paruch,Anna Malm,Monika Wujec 대한약학회 2018 Archives of Pharmacal Research Vol.41 No.6
This article describes the synthesis and antimicrobialactivity evaluation of new pipemidic acid derivatives. New compounds were obtained on the basis ofMannich reaction of 4,5-disubstituted 1,2,4-triazole-3-thiones with pipemidic acid. Antimicrobial tests revealedhigh antibacterial activity of obtained derivatives. Gramnegativerods belonging to Enterobacteriaceae family wereparticularly most sensitive to new pipemidic acid derivatives. Synthesized compounds exhibited very strongactivity towards Proteus mirabilis ATCC 12453,Salmonella typhimurium ATCC 14028 and Escherichia coliATCC 25922. The minimum inhibitory concentrations ofnew pipemidic acid derivatives which inhibited the growthof these bacteria were 0.98–7.81 μg/ml, 0.98–7.81 μg/mland 0.98–3.91 μg/ml, respectively. The antibacterialactivity of newly synthesized pipemidic acid derivatives inmany cases was far better than the activity of substancesused as positive controls (nitrofurantoin, cefuroxime,ampicillin and pipemidic acid).
Łukasz Rogal,Zbigniew Szklarz,Piotr Bobrowski,Damian Kalita,Grzegorz Garzeł,Anna Tarasek,Marcin Kot,Maciej Szlezynger 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.4
Four diff erent compositions of high entropy alloys based on Al–Co–Cr–Fe and Al–Co–Cr–Fe–Ni systems were preparedusing mechanical alloying and consolidation by spark plasma sintering. The chemical compositions of the studied alloyswere experimentally selected to obtain a BCC solid solution and mixtures of BCC with FCC. The microstructure of theAl25Co25Cr25Fe25 (all in at%) high entropy alloy consisted of a matrix with a high concentration of Al, Co and Fe, in whichspherical grains (50–200 nm) enriched in Cr were embedded. Both the matrix and grains had body centered cubic structures. The addition of nickel to a four-element system led to the formation of a multiphase composition. The microstructure of theAl20Co20Cr20Fe20Ni20, Al10Co30Cr20Fe35Ni5 and Al15Co30Cr15Fe40Ni5 HEAs consisted of fi ne grains measuring50–500 nm composed of: AlNi-B2, BCC phase, FCC or BCC solid solutions and σ-sigma phase, respectively. The complexstructure of the studied samples resulted in changeable mechanical properties. The highest compression strength of 3920 MPawas accompanied by an increased yield strength of 3500 MPa, and a low strain of 0.7%, for the Al25Co25Cr25Fe25 alloy. The addition of Ni led to the formation of plastic FCC phases responsible for a decrease in strength with increases in ductility,which, in the new non-equiatomic Al10Co30Cr20Fe35Ni5 high entropy alloy reached 6.3% at a yield strength of 1890 MPaand compression strength of 2230 MPa. The conducted abrasion studies revealed that non-equilibrium high entropy alloyshave the highest abrasion resistance.
Łukasz Rzepiński,Piotr Koślińsk,Marcin Gackowski,Marcin Koba,Zdzisław Maciejek 대한신경과학회 2022 Journal of Clinical Neurology Vol.18 No.5
Background and Purpose Aging in multiple sclerosis is associated with both disease- and age-dependent neurodegeneration. Serum metabolomic profiling of amino acids seems to be a promising method for searching for biomarkers of neurodegenerative disorders. The aim of this study was to determine the profile of nonessential amino acids in the serum of elderly patients with secondary progressive multiple sclerosis (SPMS). Methods We used high-performance liquid chromatography to evaluate the serum concentrations of nonessential amino acids in subjects aged >65 years: six patients with SPMS and 20 control subjects (CS). Results The serine and alanine levels were significantly higher in SPMS patients than in CS, whereas the concentrations of aspartic acid, arginine, and cysteine were significantly lower in SPMS patients. These observations indicate that amino acids may be involved in SPMS neurodegeneration mechanisms. There were no significant differences in the serum concentrations of the other four amino acids investigated (glutamic acid, glycine, proline, and tyrosine) between patients with SPMS and CS. Conclusions The preliminary results obtained in the study suggest that the metabolism of some amino acids is altered in patient with SPMS. We also conclude that amino acid profiling might be helpful in searching for putative biomarkers of central nervous system diseases. However, considering the multifactorial, heterogeneous, and complex nature of SPMS, further validation research involving larger study samples is required before applying these biomarkers in diagnostic practice.
Łukasz K. Kaczyn´ ski,Dorota Cais-Sokolin´ska,Artur Szwengiel 한국식품과학회 2019 Food Science and Biotechnology Vol.28 No.5
The aim of this work was the analysis of galactooligosaccharides (GOS) formation in a model mixture of goat’s milk and its permeate from microfiltration and further concentration by ultrafiltration based on the hydrolysis and transgalactosylation of lactose under various temperature and time regimes. These reactions were catalyzed by a β-galactosidase from Kluyveromyces lactis. Simultaneous hydrolysis and transgalactosylation of the milk lactose was carried out at 37, 40, and 43 °C for 6 h. The maximum GOS content in the mixture was obtained at 37 °C after 20 min. It was 6.9% of the total sugars and the degree of lactose hydrolysis was 13.3%. This was about 10% more GOS than in milk. The mixture containing GOS had a faster maximum acidification rate, 33% greater than before transgalactosylation.
Łukasiewicz, Łukasz G.,Ryu, Hye Gun,Mikhaylov, Alexander,Azarias, Cloé,Banasiewicz, Marzena,Kozankiewicz, Bolesław,Ahn, Kyo Han,Jacquemin, Denis,Rebane, Aleksander,Gryko, Daniel T. Wiley (John WileySons) 2017 Chemistry, an Asian journal Vol.12 No.14
<P>Five centrosymmetric and one dipolar pyrrolo[3,2-b]pyrroles, possessing either two or one strongly electron-withdrawing nitro group have been synthesized in a straightforward manner from simple building blocks. For the symmetric compounds, the nitroaryl groups induced spontaneous breaking of inversion symmetry in the excited state, thereby leading to large solvatofluorochromism. To study the origin of this effect, the series employed peripheral structural motifs that control the degree of conjugation via altering of dihedral angle between the 4-nitrophenyl moiety and the electron-rich core. We observed that for compounds with a larger dihedral angle, the fluorescence quantum yield decreased quickly when exposed to even moderately polar solvents. Reducing the dihedral angle (i.e., placing the nitrobenzene moiety in the same plane as the rest of the molecule) moderated the dependence on solvent polarity so that the dye exhibited significant emission, even in THF. To investigate at what stage the symmetry breaking occurs, we measured two-photon absorption (2PA) spectra and 2PA cross-sections (sigma(2PA)) for all six compounds. The 2PA transition profile of the dipolar pyrrolo[3,2-b]pyrrole, followed the corresponding one-photon absorption (1PA) spectrum, which provided an estimate of the change of the permanent electric dipole upon transition, approximate to 18D. The nominally symmetric compounds displayed an allowed 2PA transition in the wavelength range of 700-900nm. The expansion via a triple bond resulted in the largest peak value, sigma(2PA)=770GM, whereas altering the dihedral angle had no effect other than reducing the peak value two- or even three-fold. In the S0S1 transition region, the symmetric structures also showed a partial overlap between 2PA and 1PA transitions in the long-wavelength wing of the band, from which a tentative, relatively small dipole moment change, 2-7D, was deduced, thus suggesting that some small symmetry breaking may be possible in the ground state, even before major symmetry breaking occurs in the excited state.</P>