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Ferroelectricity in Ternary (CdZn)AVI Crystals
T. Wojciechowski,,P. Jakubas,P. Bogus lawski,G. Karczewski 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.1
Molecular-beam-epitaxy grown thin lms and bulk crystals of Cd1-xZnxTe have been sudied by using various experimental methods. The samples exhibit bistable conductivity, peculiar optical properties and hysteresis in the dielectric constant. The experimental results indicate that the presence of isolated Zn atoms plays a crucial role in the ferroelectric behavior of Cd1-xZnxTe. Based on the experimental results, we propose a microscopic model that takes into consideration formation of point defects in the crystal lattice, namely Zn interstitials, ZnI and cation vacancies, VCd. The presence of these defects and the formation of vacancy-interstitial pairs that constitute local electric dipoles provide a plausible explanation for the bistable conductivity, the changes in the luminescence spectra and of the hysteretic behavior of the electrical polarization. Molecular-beam-epitaxy grown thin lms and bulk crystals of Cd1-xZnxTe have been sudied by using various experimental methods. The samples exhibit bistable conductivity, peculiar optical properties and hysteresis in the dielectric constant. The experimental results indicate that the presence of isolated Zn atoms plays a crucial role in the ferroelectric behavior of Cd1-xZnxTe. Based on the experimental results, we propose a microscopic model that takes into consideration formation of point defects in the crystal lattice, namely Zn interstitials, ZnI and cation vacancies, VCd. The presence of these defects and the formation of vacancy-interstitial pairs that constitute local electric dipoles provide a plausible explanation for the bistable conductivity, the changes in the luminescence spectra and of the hysteretic behavior of the electrical polarization.
Song, Seulki,Hill, Rebecca,Choi, Kyoungwon,Wojciechowski, Konrad,Barlow, Stephen,Leisen, Johannes,Snaith, Henry J.,Marder, Seth R.,Park, Taiho unknown 2018 Nano energy Vol.49 No.-
<P><B>Abstract</B></P> <P>We report flexible planar perovskite solar cells with robust electron-transport layers (ETLs) processed at low temperature. A poly(allylamine) (PAA; 0.08 wt%) solution was deposited on a C<SUB>60</SUB> layer and heated at 150 °C for 60 s, resulting in the formation of an insoluble robust C<SUB>60</SUB>–PAA electron-transport layer (ETL) on the flexible substrate. The flexible planar perovskite solar cell with the C<SUB>60</SUB>–PAA ETL exhibited excellent properties with 83% efficiency retention (η = 15.2% without hysteresis) after 600 cycles of bending. This performance is superior to that of the flexible device with a C<SUB>60</SUB> ETL fabricated without the use of PAA (65% efficiency retention; η = 9.8% with some hysteresis).</P> <P><B>Highlights</B></P> <P> <UL> <LI> A modified fullerene-based electron transport layer is proposed for stable flexible perovskite device. </LI> <LI> A poly(allylamine) (PAA; 0.08 wt%) solution was deposited on a C<SUB>60</SUB> layer to form a C<SUB>60</SUB>-PAA. </LI> <LI> C<SUB>60</SUB>–PAA electron-transport layer (ETL) is insoluble in perovskite precursor solution. </LI> <LI> Flexible planar perovskite solar cell with the C<SUB>60</SUB>–PAA ETL exhibited excellent properties with 83% efficiency retention. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Naturalized Dyes – A Way to Increase Susceptibility for Microbiological Degradation
Ma gorzata Piotrowska,Agnieszka Szymczak,Krzysztof Wojciechowski 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.1
Aim of the study was the determination of theinfluence of the D-gluconic acid and its acetyl derivative(2,3,4,5,6-penta-O-acetyl-D-gluconic acid) on microbiologicaldegradation in aerobic conditions of azo dyes(Schäffer salt and I acid derivatives). The rest of thealdonic acid and its acetylated form in the structure of azodye play a role of an additional source of carbon for theused microorganisms. To investigations were used fungus:Aspergillus niger, Geotrichum condidum and bacterias:Pseudomonas fluorescens, Streptomyces roseochromogens. From all tested microorganisms only Aspergillus niger andPseudomonas fluorescens show sufficient ability todecomposition of tested dyes during research carried out inshaken culture.
Radoslaw W. Maruda,Grzegorz M. Krolczyk,Szymon Wojciechowski,Krzysztof Zak,Witold Habrat,Piotr Nieslony 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.4
The paper presents an original study of the influence of extreme pressure and anti-wear (EP/AW) additives on the surface topography of double-phase steel during turning with different cooling media and variable flow rates. The obtained surface topographies were compared using frequency and fractal analyses for dry, minimum quantity cooling lubrication (MQCL), and MQCL + EP/AW methods. Results showed that the addition of phosphate ester-based additives to an active medium caused the formation of tribofilm on the tool-chip interface and thus a change in the lubricating properties by reducing friction. The tool wear and the formation of the thin-layered tribofilm were also incorporated. The application of the MQCL method with the EP/AW additives led to a decrease in particular surface topography parameters from 8 % to 38 % in comparison with the effects of dry cutting and from 6 % to 35 % in comparison with the effects of machining under MQCL conditions. An exception was the result obtained for the surface roughness height parameter Sp, which was higher than that obtained after the MQCL + EP/AW process for the lowest investigated feed per revolution f = 0.1 mm/rev. This observation was correlated with the uneven formation of the tribofilm on the machined surface. The phosphate ester-based additive used in the MQCL + EP/AW method contributed to achieving tool wear that was less than that obtained by the processes conducted under dry and MQCL conditions.
Yttrium as a New Threshold Detector for Fast Neutron Energy Spectrum (>10 MeV) Measurement
M. Bielewicz,S. Kilim,E. Strugalska-Gola,M. Szuta,A. Wojciechowski 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
Results of two experiments with Yttrium 89 probe are presented. The experiment assembly (U/Pb model) was irradiated with Dubna NUCLOTRON for 1.6 and 2.52 GeV deuteron beam and we obtain Neutron Energy Spectrum inside whole 3D model by using threshold energy reaction. Normally in experiment like this one uses neutron activation detectors made from gold (^(197)Au), cobalt (^(59)Co), bismuth (^(209)Bi) etc. Detector, yttrium (^(89)Y) was proposed. Yttrium detectors give quite good results for neutron energy spectrum from 10 MeV to about 50 MeV.
Expanding the Diversity of Allosteric Bcr-Abl Inhibitors
Deng, Xianming,Okram, Barun,Ding, Qiang,Zhang, Jianming,Choi, Yongmun,Adriá,n, Francisco J.,Wojciechowski, Amy,Zhang, Guobao,Che, Jianwei,Bursulaya, Badry,Cowan-Jacob, Sandra W.,Rummel, Gabriele American Chemical Society 2010 Journal of medicinal chemistry Vol.53 No.19
<P/><P>Inhibition of Bcr-Abl kinase activity by imatinib for the treatment of chronic myeloid leukemia (CML) currently serves as the paradigm for targeting dominant oncogenes with small molecules. We recently reported the discovery of GNF-2 (<B>1</B>) and GNF-5 (<B>2</B>) as selective non-ATP competitive inhibitors of cellular Bcr-Abl kinase activity that target the myristate binding site. Here, we used cell-based structure−activity relationships to guide the optimization and diversification of ligands that are capable of binding to the myristate binding site and rationalize the findings based upon an Abl−compound <B>1</B> cocrystal. We elucidate the structure−activity relationships required to obtain potent antiproliferative activity against Bcr-Abl transformed cells and report the discovery of new compounds (<B>5g</B>,<B> 5h</B>,<B> 6a</B>,<B> 14d</B>, and <B>21j-I)</B> that display improved potency or pharmacological properties. This work demonstrates that a variety of structures can effectively target the Bcr-Abl myristate binding site and provides new leads for developing drugs that can target this binding site.</P>