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71.
Aleksandra S.Kosti 《Algebra Colloquium》2021,28(4):625-634
Let R be an associative unital ring and not necessarily commutative.We analyze conditions under which every n × n matrix A over R is expressible as a sum A =E1 +…+ Es + N of (commuting) idempotent matrices Ei and a nilpotent matrix N. 相似文献
72.
Selenium nanoparticles (SeNPs) have attracted great attention in recent years due to their unique properties and potential bioactivities. While the production of SeNPs has been long reported, there is little news about the influence of reaction conditions and clean-up procedure on their physical properties (e.g., shape, size) as well as their antioxidant activity. This study takes up this issue. SeNPs were synthesized by two methods using cysteine and ascorbic acid as selenium reductants. The reactions were performed with and without the use of polyvinyl alcohol as a stabilizer. After the synthesis, SeNPs were cleaned using various procedures. The antioxidant properties of the obtained SeNPs were investigated using DPPH and hydroxyl radical scavenging assays. It was found that their antioxidant activity does not always depend only on the nanoparticles size but also on their homogeneity. Moreover, the size and morphology of selenium nanoparticles are controlled by the clean-up step. 相似文献
73.
A benzo[a]anthraquinone ring system, common to a group of angucycline antibiotics, has been prepared by a unique cascade of reactions. The reaction sequence was initiated by a Suzuki-Miyaura cross-coupling between a bromoquinone and vinyl boronic anhdyride. The reaction product is proposed to undergo a 6π-electron cyclization triggered by reductive activation of the quinone. The reaction process is proposed to be autocatalytic. 相似文献
74.
Aleksandra Zapadinskaya 《Central European Journal of Mathematics》2011,9(2):356-363
We prove a dimension compression estimate for homeomorphic mappings of exponentially integrable distortion via a modulus of
continuity result by D. Herron and P. Koskela [Mappings of finite distortion: gauge dimension of generalized quasicircles,
Illinois J. Math., 2003, 47(4), 1243–1259]. The essential sharpness of our estimate is demonstrated by an example. 相似文献
75.
D. Kamińska A. Gajos E. Czerwiński D. Alfs T. Bednarski P. Białas C. Curceanu K. Dulski B. Głowacz N. Gupta-Sharma M. Gorgol B. C. Hiesmayr B. Jasińska G. Korcyl P. Kowalski W. Krzemień N. Krawczyk E. Kubicz M. Mohammed Sz. Niedźwiecki M. Pawlik-Niedźwiecka L. Raczyński Z. Rudy M. Silarski A. Wieczorek W. Wiślicki B. Zgardzińska M. Zieliński P. Moskal 《The European Physical Journal C - Particles and Fields》2016,76(8):445
76.
Leszek A. Dobrzański Marek Szindler Aleksandra Drygała Magdalena M. Szindler 《Central European Journal of Physics》2014,12(9):666-670
The paper presents the possibility of using Al2O3 antireflection coatings deposited by atomic layer deposition ALD. The ALD method is based on alternate pulsing of the precursor gases and vapors onto the substrate surface and then chemisorption or surface reaction of the precursors. The reactor is purged with an inert gas between the precursor pulses. The Al2O3 thin film in structure of the finished solar cells can play the role of both antireflection and passivation layer which will simplify the process. For this research 50×50 mm monocrystalline silicon solar cells with one bus bar have been used. The metallic contacts were prepared by screen printing method and Al2O3 antireflection coating by ALD method. Results and their analysis allow to conclude that the Al2O3 antireflection coating deposited by ALD has a significant impact on the optoelectronic properties of the silicon solar cell. For about 80 nm of Al2O3 the best results were obtained in the wavelength range of 400 to 800 nm reducing the reflection to less than 1%. The difference in the solar cells efficiency between with and without antireflection coating was 5.28%. The LBIC scan measurements may indicate a positive influence of the thin film Al2O3 on the bulk passivation of the silicon. 相似文献
77.
The heats of formation of LnVO4-type salts (whereLn=Y, La, Sm, Nd, Gd and Dy) were determined by thermal analysis in the reactions of melts of stable lanthanides and V2O5 in a 1 ∶ 1 mole ratio. Heats of formation of LnVO4-type salts can be determined using non-stoichiometric mixtures of the substrates as well. With the aid of DTA the apparent activation energies of the syntheses of the orthovanadates of these lanthanides were calculated. 相似文献
78.
Using the all-optical poling method, we observed the formation of a surface-relief grating (SRG) in an amorphous polymer film containing azo dye molecules in side chain positions. The experiment consists of a seeding-type process. We used a recently described experimental setup that permits a periodic nonlinear pattern to be produced by the index dispersion of glass. The particular configuration permits photoinduced translation diffusion of the azo chromophores to be observed as the origin of the SRG formation. Analyses of the gratings recorded by use of s (TE) and p (TM) polarization of the writing beams are conducted by atomic-force microscopy. The effect is attributed to mass transport from regions of high isomerization activity to regions of lower activity. 相似文献
79.
Aleksandra M. Korostyshevskaya 《Applied magnetic resonance》2011,41(2-4):537-542
Magnetic resonance imaging (MRI) abilities in pre- and postnatal monitoring of cytomegalovirus-related brain lesions from early prenatal period to infancy are described. Objective of our study is to illustrate the gradual evolution of intracranial abnormalities in a single patient through serial pre- and postnatal MRI. It demonstrates the progress of a cerebral cytomegalovirus infection from fetal to postnatal life with the lack of concordance between prenatal ultrasonography and MRI, and proves the great importance of MRI, being in most cases the only tool for early detection and monitoring of this potentially devastating entity. It was shown that the additional postnatal MRI increases the possibilities in the specific characterization of lesions revealed in the fetus brain, which account for a wide spectrum of different sequences and best spatial resolution of postnatal MRI in comparison with the prenatal one. 相似文献
80.
Sebastian Mendrek Aleksandra Mendrek Hans‐Juergen Adler Andrzej Dworak Dirk Kuckling 《Journal of polymer science. Part A, Polymer chemistry》2009,47(7):1782-1794
Block copolymers of poly(glycidol)‐b‐poly(4‐vinylpyridine) were obtained by ATRP of 4‐vinylpyridine initiated by ω‐(2‐chloropropionyl) poly(glycidol) macroinitiators. By changing the monomer/macroinitiator ratio in the synthesis polymers with varied P4VP/PGl molar ratio were obtained. The obtained block copolymers showed pH sensitive solubility. It was found that the linkage of a hydrophilic poly(glycidol) block to a P4VP influenced the pKa value of P4VP. DLS measurements showed the formation of fully collapsed aggregates exceeding pH 4.7. Above this pH values the collapsed P4VP core of the aggregates was stabilized by a surrounding hydrophilic poly(glycidol) corona. The size of the aggregates depended significantly upon the composition of the block copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1782–1794, 2009 相似文献