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101.
102.
A method for the determination of vapor–liquid phase diagram structure of five-component systems based on the analysis of types and Poincare indexes of singular points of the geometric scan and full structure of the concentration simplex is proposed. Validity of the proposed method was demonstrated by vapor–liquid equilibrium modeling in five-component mixtures: ethanol + water + toluene + butanol + chlorbenzene and acetone + chloroform + ethanol + cyclohexane + water. 相似文献
103.
Teng-yi Huang Anastasia Kharlamova Scott A. McLuckey 《Journal of the American Society for Mass Spectrometry》2010,21(1):144-153
Gas-phase dissociation of model locked nucleic acid (LNA) oligonucleotides and functional LNA-DNA chimeras have been investigated
as a function of precursor ion charge state using ion trap collision-induced dissociation (CID). For the model LNA 5 and 8
mer, containing all four LNA monomers in the sequence, cleavage of all backbone bonds, generating a/w-, b/x-, c/y-, and d/z-ions,
was observed with no significant preference at lower charge states. Base loss ions, except loss of thymine, from the cleavage
of N-glycosidic bonds were also present. In general, complete sequence coverage was achieved in all charge states. For the
two LNA-DNA chimeras, however, dramatic differences in the relative contributions of the competing dissociation channels were
observed among different precursor ion charge states. At lower charge states, sequence information limited to the a-Base/w-fragment
ions from cleavage of the 3′C-O bond of DNA nucleotides, except thymidine (dT), was acquired from CID of both the LNA gapmer
and mixmer ions. On the other hand, extensive fragmentation from various dissociation channels was observed from post-ion/ion
ion trap CID of the higher charge state ions of both LNA-DNA chimeras. This report demonstrates that tandem mass spectrometry
is effective in the sequence characterization of LNA oligonucleotides and LNA-DNA chimeric therapeutics. 相似文献
104.
A new, rapid, sensitive and selective HPLC method with fluorescence detection is described for the simultaneous determination of 12 sulfonamides, in the presence of putrescine as internal standard, after pre‐column derivatization with fluorescamine. The drugs were separated on a Chromolith Performance RP‐18 column (100×4.6 mm), using a gradient elution with a binary mobile phase of methanol/0.05 M acetate buffer (pH 3.4). Linearity of derivatization was obtained for concentrations from 3.0 to 300 μg/L in standard solutions. The whole procedure was evaluated and fully validated, according to the European Union Decision 2002/657/EC, for the determination of sulfonamides in turkey muscle and hen eggs following SPE. The LODs varied from 2 to 17 μg/kg in turkey and 2 to 15 μg/kg in egg samples. The average recoveries ranged between 96.9–108.6% in turkey muscle and 96.0–108.4% in egg samples, respectively. 相似文献
105.
Anastasia Rusina Maxim Durach Mark I. Stockman 《Applied Physics A: Materials Science & Processing》2010,100(2):375-378
In this Letter we develop a theory of spoof plasmons propagating on real metals perforated with planar periodic grooves. Deviation
from the spoof plasmons on perfect conductor due to finite skin depth has been analytically described. This allowed us to
investigate important propagation characteristics of spoof plasmons such as quality factor and propagation length as the function
of the geometrical parameters of the structure. We have also considered THz field confinement by adiabatic increase of the
depth of the grooves. It is shown that the finite skin depth limits the propagation length of spoof plasmons as well as a
possibility to localize THz field. Geometrical parameters of the structure are found which provide optimal guiding and localization
of THz energy. 相似文献
106.
We start from a realistic half space model for thermal imaging, which we then use to develop a mathematical asymptotic analysis well suited for the design of reconstruction algorithms. We seek to reconstruct thermal anomalies only through their rough features. With this way our proposed algorithms are stable against measurement noise and geometry perturbations. Based on rigorous asymptotic estimates, we first obtain an approximation for the temperature profile which we then use to design nonit-erative detection algorithms. We show on numerical simulations evidence that they are accurate and robust. Moreover, we provide a mathematical model for ultrasonic temperature imaging, which is an important technique in cancerous tissue ablation therapy.AMS subject classifications: 35R20, 35B30 相似文献
107.
The paper deals with the assignment of a single server to two retrial queues. Each customer reapplies for service after an
exponentially distributed amount of time. The server operates at customer dependent exponential rates. There are holding costs
and costs during service per customer and per unit of time. We provide conditions on which it is optimal to allocate the server
to queue 1 or 2 in order to minimize the expected total costs until the system is cleared. 相似文献
108.
Ethyl 4-methyl-2-oxo-7-phenylthio-2,3,6,7-tetrahydro-1H-1,3-diazepine-5-carboxylate and/or ethyl 6-methyl-2-oxo-4-(phenylthiomethyl)-1,2,3,4-tetrahydropyrimidine-5-carboxylate were obtained in the reaction of ethyl 4-chloromethyl-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate with PhSNa or PhSK with or without PhSH, depending on the reagent ratio, reaction time, or temperature, as a result of ring expansion and/or nucleophilic substitution. The reaction pathway was affected strongly by the basicity-nucleophilicity of the reaction media. The results obtained were confirmed by reactions of 4-mesyloxymethyl-6-methyl-5-tosyltetrahydropyrimidin-2-one with PhSNa/PhSH and ethyl 4-chloromethyl-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate with NaCN/HCN or NaCH(COOEt)2/CH2(COOEt)2. 相似文献
109.
Anastasia A. Fesenko 《Tetrahedron》2010,66(35):7219-462
A four-step method for the synthesis of 5-arylsulfonyl-substituted 1,2-dihydropyrimidin-2-ones has been developed. The reaction of readily available N-[(1-acetoxy-2,2,2-trichloro)ethyl]ureas with sodium enolates of α-arylsulfonylketones followed by heterocyclization-dehydration of the oxoalkylureas formed gave 5-arylsulfonyl-4-trichloromethyl-1,2,3,4-tetrahydropyrimidin-2-ones. The latter, in the presence of strong bases, eliminate CHCl3 to give the target compounds. 相似文献