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91.
Mazurek U McFarland MA Marshall AG Lifshitz C 《European journal of mass spectrometry (Chichester, England)》2004,10(6):755-758
A method to isolate isomers in a Fourier transform ion cyclotron resonance mass spectrometer on the basis of their different hydrogen/deuterium exchange rates has been developed and applied to the protonated serine octamer cluster. Isolation allows interrogation of each isomer by infrared multi-photon dissociation to determine any differences in the building blocks that form these clusters. The experimental results strongly support previous assignments of an all-zwitterion structure to the slower-exchanging isomer and an all-neutral structure to its faster- exchanging counterpart. 相似文献
92.
Let S be a non-commutative associative ring with an identity element and G be a finite group of ring automorhphisms of S. By exploiting Morita Theory, a bijection between subsets of SpecS and spec(SG ) is constructed. This Morita formulation is shown to be equivalent to a much more natural definition of the bijection, one in which the strong relationship between the rings S and SG is clearly manifest. Indeed, the bijection is shown to have implications for a number of ring-theoretic properties of rings S and SG . One such property being prime rank. A topological treatment of the bijection using quotient Zariski topologies yields a homeomorphism which exhibits the structural similarities between S and S G. The final section is devoted to a special case: charS - q, q prime, and G a q-group. In this case, it is shown that a prime ideal of the skew group ring S*G is uniquely determined by its intersection with R. 相似文献
93.
Petr Bělina Petra Šulcová Miroslav Trojan Pavel Mazurek 《Central European Journal of Chemistry》2007,5(3):706-714
New binary lanthanum-aluminum triphosphates were synthesized by thermal-condensation method from H3PO4, La2O3 and Al(OH)3. These pigments could be potentially used as special inorganic pigments; their corrosion-inhibition properties were widely
studied. Synthesis conditions were determined on the basis of DTA and TG measurements. The products were also characterized
by X-ray diffraction analysis. Physical properties — density by pycnometric method, particle size distribution, oil number
and critical pigment volume concentration (CPVC), pH and specific conductivity of their aqueous extracts were also determined.
相似文献
94.
Let R be a ring, S a strictly ordered monoid and a monoid homomorphism. In this paper we obtain some necessary conditions for the skew generalized power series ring RS,ω to be right (respectively left) uniserial, and we prove that these conditions are also sufficient when the monoid S is commutative or totally ordered. 相似文献
95.
Ryszard Mazurek 《Semigroup Forum》2011,83(2):335-342
A right-chain semigroup is a semigroup whose right ideals are totally ordered by set inclusion. The main result of this paper
says that if S is a right-chain semigroup admitting a ring structure, then either S is a null semigroup with two elements or sS=S for some s∈S. Using this we give an elementary proof of Oman’s characterization of semigroups admitting a ring structure whose subsemigroups
(containing zero) form a chain. We also apply this result, along with two other results proved in this paper, to show that
no nontrivial multiplicative bounded interval semigroup on the real line ℝ admits a ring structure, obtaining the main results
of Kemprasit et al. (ScienceAsia 36: 85–88, 2010). 相似文献
96.
Semigroup Forum - For any commutative semigroup S and positive integer m the power function $$f: S \rightarrow S$$ defined by $$f(x) = x^m$$ is an endomorphism of S. We partly solve the... 相似文献
97.
Witowska-Jarosz J Jarończyk M Mazurek AP Sylte I Bojarski AJ Chilmonczyk Z Jarosz M 《Analytical and bioanalytical chemistry》2012,402(1):537-541
Six synthesized 6-nitroquipazine derivatives were examined by electron ionization (EI) and electrospray ionization (ESI) mass
spectrometry in positive and negative ion mode. The compounds exhibit high affinity for the serotonin transporter (SERT) and
belong to a new class of SERT inhibitors. The EI mass spectra registered in negative ion mode showed prominent molecular ions
for all the compounds studied. All EI mass spectra and all ESI mass spectra showed similar fragmentation pathways of molecular
ions, but the pathways differed between EI and ESI. The differences were explained with the aid of theoretical evaluation
of the stability of the respective radical ions (EI MS) and protonated ions (ESI MS). 相似文献
98.
The formation of protonated serine octamer clusters from homochiral and heterochiral monomer solutions was investigated. The well-established preference for homochiral cluster formation was found to originate from collision-induced dissociation of the less stable ion population B prior to reaching the mass spectrometer's analyzer cell. In addition, collision-induced dissociation experiments were undertaken to investigate the relative stabilities of populations A and B and infrared multi-photon dissociation experiments addressed the relative stabilities of the protonated serine octamer cluster and its metaclusters. Isotopically-labeled serine was used throughout the experiments. 相似文献
99.
Loosli A Rusbandi UE Gradinaru J Bernauer K Schlaepfer CW Meyer M Mazurek S Novic M Ward TR 《Inorganic chemistry》2006,45(2):660-668
Incorporation of a biotinylated ruthenium tris(bipyridine) [Ru(bpy)(2)(Biot-bpy)](2+) (1) in either avidin or streptavidin-(strept)avidin-can be conveniently followed by circular dichroism spectroscopy. To determine the stepwise association constants, cooperativity, and chiral discrimination properties, diastereopure (Lambda and Delta)-1 species were synthesized and incorporated in tetrameric (strept)avidin to afford (Delta-[Ru(bpy)(2)(Biot-bpy)](2+))(x)() subsetavidin, (Lambda-[Ru(bpy)(2)(Biot-bpy)](2+))(x)() subsetavidin, (Delta-[Ru(bpy)(2)(Biot-bpy)](2+))(x)() subsetstreptavidin, and (Lambda-[Ru(bpy)(2)(Biot-bpy)](2+))(x)() subsetstreptavidin (x = 1-4) For these four systems, the overall stability constants are log beta(4) = 28.6, 30.3, 36.2, and 36.4, respectively. Critical analysis of the CD titrations data suggests a strong cooperativity between the first and the second binding event (x = 1, 2) and a pronounced difference in affinity between avidin and streptavidin for the dicationic guest 1 as well as modest enantiodiscrimination properties with avidin as host. 相似文献
100.
Sylwester Mazurek Maciej Wodarczyk Sonia Pielorz Piotr Okiczyc Piotr M. Ku Gabriela Dugosz Diana Vidal-Yaez Roman Szostak 《Molecules (Basel, Switzerland)》2022,27(12)
Poplar bark and leaves can be an attractive source of salicylates and other biologically active compounds used in medicine. However, the biochemical variability of poplar material requires a standardization prior to processing. The official analytical protocols used in the pharmaceutical industry rely on the extraction of active compounds, which makes their determination long and costly. An analysis of plant materials in their native state can be performed using vibrational spectroscopy. This paper presents for the first time a comparison of diffuse reflectance in the near- and mid-infrared regions, attenuated total reflection, and Raman spectroscopy used for the simultaneous determination of salicylates and flavonoids in poplar bark and leaves. Based on 185 spectra of various poplar species and hybrid powdered samples, partial least squares regression models, characterized by the relative standard errors of prediction in the 4.5–9.9% range for both calibration and validation sets, were developed. These models allow for fast and precise quantification of the studied active compounds in poplar bark and leaves without any chemical sample treatment. 相似文献