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51.
Characterization of polyphosphoesters by fourier transform ion cyclotron resonance mass spectrometry
Malgorzata A. Kaczorowska Helen J. Cooper 《Journal of the American Society for Mass Spectrometry》2009,20(12):2238-2247
FT-ICR mass spectrometry, together with collision-induced dissociation and electron capture dissociation, has been used to
characterize the polyphosphoester poly[1,4-bis(hydroxyethyl)terephthalate-alt-ethyloxyphosphate] and its degradation products. Three degradation pathways were elucidated: hydrolysis of the phosphate-[1,4-bis(hydroxyethyl)terephthalate]
bonds; hydrolysis of the phosphate-ethoxy bonds; and hydrolysis of the ethyl-terephthalate bonds. The dominant degradation
reactions were those that involved the phosphate groups. This work constitutes the first application of mass spectrometry
to the characterization of polyphosphoesters and demonstrates the suitability of high mass accuracy FT-ICR mass spectrometry,
with CID and ECD, for the structural analysis of polyphosphoesters and their degradation products. 相似文献
52.
An investigation of energetic properties of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) layers deposited on glass, mica, and PMMA (poly(methyl methacrylate)) surfaces was carried out by means of contact angles measurements (advancing and receding) for three probe liquids (diiodomethane, water, and formamide). DPPC was deposited on the surfaces from water (on glass and mica) or methanol (on PMMA) solutions. The topography of the tested surfaces was determined with a help of scanning electron microscopy (SEM) and atomic force microscopy (AFM). Using the measured contact angles, the total apparent surface free energy and its components of the studied layers were determined from van Oss et al.'s (Lifshitz-van der Waals and acid-base components, LWAB) and contact angle hysteresis (CAH) approaches. It allowed us to learn about changes in the surface free energy of the layers (hydrophobicity/hydrophilicity) depending on their number and kind of support. It was found that the changes in the energy greatly depended on the surface properties of the substrate as well as the statistical number of monolayers of DPPC. However, principal changes took place for first three monolayers. 相似文献
53.
Oriented inclusion complexes of chloroform@cryptophane-A and chloroform@bis-cryptophane were prepared using a nematic thermotropic liquid crystal (ZLI 1132), and the alignment and magnetic resonance properties of these host-guest systems were studied via (13)C NMR of the labeled guests. Large (1)H-(13)C dipolar splittings for (13)CHCl(3) guests indicated significantly enhanced (approximately 2-fold) ordering for the trapped vs. free ligands under all conditions studied, with similar ordering observed for the two complexes-despite significant differences in size and motional freedom between the hosts. For each environment, variable-temperature studies permitted the sign and magnitude of the order parameter for chloroform's C-H bond to be independently determined from the (13)C chemical shift anisotropy (CSA) shifts (via the gradient method) and the restored (1)H-(13)C dipolar couplings. In both systems, the results are consistent with overall alignment of the complexes such that the cage principal axis lies roughly perpendicular to the LC director. 相似文献
54.
Grzegorz Zajac Agnieszka Kaczor Katarzyna Chruszcz‐Lipska Jan Cz. Dobrowolski Malgorzata Baranska 《Journal of Raman spectroscopy : JRS》2014,45(10):859-862
Raman optical activity (ROA) spectra were calculated for a set of conformers of astaxanthin, which is a non‐rigid molecule exhibiting strong resonance enhancement in the visible range. Single electronic state theory of the Resonance ROA (RROA) predicts the spectrum to be monosigned. For astaxanthin, it appeared that some of the conformers exhibit different sign of the bands than the other conformers. As a result, the conformer population averaged spectrum of astaxanthin can exhibit both signs of the bands, or be monosigned depending on which conformers are dominating, that reflects a departure from the single electronic state approximation. Moreover, use of different basis sets and/or density functional theory (DFT) functionals results in different conformer populations, thus yielding again either monosigned ROA spectrum or with bands of both signs. Consequences of these two findings for the astaxanthin RROA spectrum are discussed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
55.
Malgorzata Frik Dr. Josefina Jiménez Ismael Gracia Prof. Larry R. Falvello Sarya Abi‐Habib Karina Suriel Prof. Theodore R. Muth Prof. María Contel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(12):3659-3674
The reaction of new dinuclear gold(I) organometallic complexes containing mesityl ligands and bridging bidentate phosphanes [Au2(mes)2(μ‐LL)] (LL=dppe: 1,2‐bis(diphenylphosphano)ethane 1 a , and water‐soluble dppy: 1,2‐bis(di‐3‐pyridylphosphano)ethane 1 b ) with Ag+ and Cu+ lead to the formation of a family of heterometallic clusters with mesityl bridging ligands of the general formula [Au2M(μ‐mes)2(μ‐LL)][A] (M=Ag, A=ClO4?, LL=dppe 2 a , dppy 2 b ; M=Ag, A=SO3CF3?, LL=dppe 3 a , dppy 3 b ; M=Cu, A=PF6?, LL=dppe 4 a , dppy 4 b ). The new compounds were characterized by different spectroscopic techniques and mass spectrometry The crystal structures of [Au2(mes)2(μ‐dppy)] ( 1 b ) and [Au2Ag(μ‐mes)2(μ‐dppe)][SO3CF3] ( 3 a ) were determined by a single‐crystal X‐ray diffraction study. 3 a in solid state is not a cyclic trinuclear Au2Ag derivative but it gives an open polymeric structure instead, with the {Au2(μ‐dppe)} fragments “linked” by {Ag(μ‐mes)2} units. The very short distances of 2.7559(6) Å (Au? Ag) and 2.9229(8) Å (Au? Au) are indicative of gold–silver (metallophilic) and aurophilic interactions. A systematic study of their luminescence properties revealed that all compounds are brightly luminescent in solid state, at room temperature (RT) and at 77 K, or in frozen DMSO solutions with lifetimes in the microsecond range and probably due to the self‐aggregation of [Au2M(μ‐mes)2(μ‐LL)]+ units (M=Ag or Cu; LL=dppe or dppy) into an extended chain structure, through Au? Au and/or Au? M metallophilic interactions, as that observed for 3 a . In solid state the heterometallic Au2M complexes with dppe ( 2 a – 4 a ) show a shift of emission maxima (from ca. 430 to the range of 520‐540 nm) as compared to the parent dinuclear organometallic product 1 a while the complexes with dppy ( 2 b–4 b ) display a more moderate shift (505 for 1 b to a max of 563 nm for 4 b ). More importantly, compound [Au2Ag(μ‐mes)2(μ‐dppy)]ClO4 ( 2 b ) resulted luminescent in diluted DMSO solution at room temperature. Previously reported compound [Au2Cl2(μ‐LL)] (LL dppy 5 b ) was also studied for comparative purposes. The antimicrobial activity of 1–5 and Ag[A] (A=ClO4?, SO3CF3?) against Gram‐positive and Gram‐negative bacteria and yeast was evaluated. Most tested compounds displayed moderate to high antibacterial activity while heteronuclear Au2M derivatives with dppe ( 2 a – 4 a ) were the more active (minimum inhibitory concentration 10 to 1 μg mL?1). Compounds containing silver were ten times more active to Gram‐negative bacteria than the parent dinuclear compound 1 a or silver salts. Au2Ag compounds with dppy ( 2 b , 3 b ) were also potent against fungi. 相似文献
56.
The effect of mechanical activation on the structure and thermal reactions of glasses has been studied on the example of Na–Al–Fe
phosphate glasses. These glasses are used in nuclear technology for immobilization of radioactive waste. The glasses were
activated by grinding in a planetary mill. Mechanical activation causes a decrease of the T
g temperature as well as of the glass crystallization temperature. The type of crystalline phases formed and the quantitative
proportions between them are changing. Analysis of inter-atomic interactions in the structure of glass was applied to explain
the observed regularities governing the crystallization of the activated glasses. 相似文献
57.
58.
Numerical Algorithms - In a number of our previous papers, we have proposed interval versions of multistep methods (explicit and implicit), including interval predictor-corrector methods, in which... 相似文献
59.
This paper presents an ADBASE-based parallel algorithm forsolving multiple objective linear programs (MOLPs). Job balance,speedup and scalability are of primary interest in evaluatingefficiency of the new algorithm. The scalability of a parallelalgorithm is a measure of its capacity to increase performance withrespect to the number of processors used. Implementation results onIntel iPSC/2 and Paragon multiprocessors show that the algorithmsignificantly speeds up the process of solving MOLPs, which isunderstood as generating all or some efficient extreme points andunbounded efficient edges. The algorithm is shown to be scalable andgives better results for large problems. Motivation andjustification for solving large MOLPs are also included. 相似文献
60.
Zurowski Radoslaw Gluszek Malgorzata Antosik Agnieszka Pietrzak Emilia Rokicki Gabriel Szafran Mikolaj 《Journal of Thermal Analysis and Calorimetry》2018,133(1):453-463
Journal of Thermal Analysis and Calorimetry - To study the effect of ionic liquids (ILs) of the microstructure on the surface of the coal, four ILs ([Emim][BF4], [Bmim][BF4], [Bmim][NO3], and... 相似文献