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111.
We prove that the numerical semigroups associated to the combinatorial configurations satisfy a family of linear, non-homogeneous, symmetric patterns. We use these patterns to prove an upper bound of the conductor and we also give an upper bound of the multiplicity. Also, we compare bounds of the conductor of numerical semigroups associated to balanced configurations, and to configurations with coprime parameters. The proof of the latter involves a bound of the conductor of prime power generated numerical semigroups. 相似文献
112.
113.
David L. Stokes G. D. Griffin Tuan Vo-Dinh 《Analytical and bioanalytical chemistry》2001,369(3-4):295-301
This work demonstrates the detection of E. coli using a 2-dimensional photosensor array biochip which is efficiently equipped with a microfluidics sample/reagent delivery
system for on-chip monitoring of bioassays. The biochip features a 4 × 4 array of independently operating photodiodes that
are integrated along with amplifiers, discriminators and logic circuitry on a single platform. The microfluidics system includes
a single 0.4 mL reaction chamber which houses a sampling platform that selectively captures detection probes from a sample
through the use of immobilized bioreceptors. The independently operating photodiodes allow simultaneous monitoring of multiple
samples. In this study the sampling platform is a cellulosic membrane that is exposed to E. coli organisms and subsequently analyzed using a sandwich immunoassay involving a Cy5-labeled antibody probe. The combined effectiveness
of the integrated circuit (IC) biochip and the immunoassay is evaluated for assays performed both by conventional laboratory
means followed by detection with the IC biochip, and through the use of the microfluidics system for on-chip detection. Highlights
of the studies show that the biochip has a linear dynamic range of three orders of magnitude observed for conventional assays,
and can detect 20 E. coli organisms. Selective detection of E. coli in a complex medium, milk diluent, is also reported for both off-chip and on-chip assays.
Received: 13 October 2000 / Revised: 13 November 2000 / Accepted: 13 November 2000 相似文献
114.
Jan Ilavsky Kristoffer K. Stokes Michael C. Berg Randy A. Mrozek Joseph L. Lenhart Frederick L. Beyer Jan W. Andzelm 《Journal of Polymer Science.Polymer Physics》2011,49(20):1479-1491
Dynamic density functional theory calculations were performed for thermoplastic elastomer gels composed of an ABA triblock copolymer immersed in a B‐attractive solvent. The triblock copolymer model was parameterized for poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] (SEBS), while the solvent model was parameterized for the hydrocarbon oil tetradecane. The effect of the solvent concentration and S‐EB interaction on the morphology was investigated, where complementary experimental data was used to validate results at χABN ≈ 100. Agreement was observed at solvent volume fractions of 0.2, 0.4, and 0.6, which correspond to the cylindrical, spherical, and spherical phases, respectively. Qualitative agreement was observed for 0.8 volume fraction solvent, where a core‐shell spherical micelle morphology was found. For a 50/50 vol % mixture of polymer/solvent, the effect of solvent molecular weight on the morphology was considered, where a transition between micro and macrophase separation was predicted at a critical solvent molecular weight. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1479–1491, 2011 相似文献
115.
Garcia-Sartal C Taebunpakul S Stokes E Barciela-Alonso Mdel C Bermejo-Barrera P Goenaga-Infante H 《Analytical and bioanalytical chemistry》2012,402(10):3359-3369
Edible seaweed consumption is a route of exposure to arsenic. However, little attention has been paid to estimate the bioaccessibility
and/or bioavailability of arsenosugars in edible seaweed and their possible degradation products during gastrointestinal digestion.
This work presents first use of combined inductively coupled plasma mass spectroscopy (ICP-MS) with electrospray ionization
tandem mass spectrometry (ESI-MS/MS) with two-dimensional HPLC (size exclusion followed by anion exchange) to compare the
qualitative and quantitative arsenosugars speciation of different edible seaweed with that of their bioavailable fraction
as obtained using an in vitro gastrointestinal digestion procedure. Optimal extraction conditions for As species from four
seaweed namely kombu, wakame, nori and sea lettuce were selected as a compromise between As extraction efficiency and preservation
of compound identity. For most investigated samples, the use of ammonium acetate buffer as extractant and 1 h sonication in
a water bath followed by HPLC-ICP-MS resulted in 40–61% of the total As to be found in the buffered aqueous extract, of which
86–110% was present as arsenosugars (glycerol sugar, phosphate sugar and sulfonate sugar for wakame and kombu and glycerol
sugar and phosphate sugar for nori). The exception was sea lettuce, for which the arsenosugar fraction (glycerol sugar, phosphate
sugar) only comprised 44% of the total extracted As. Interestingly, the ratio of arsenobetaine and dimethylarsinic acid to
arsenosugars in sea lettuce extracts seemed higher than that for the rest of investigated samples. After in vitro gastrointestinal
digestion, approximately 11–16% of the total As in the solid sample was found in the dialyzates with arsenosugars comprising
93–120% and 41% of the dialyzable As fraction for kombu, wakame, nori and sea lettuce, respectively. Moreover, the relative
As species distribution in seaweed-buffered extracts and dialyzates was found to be very similar. Collection of specific fractions
from the size-exclusion column to be analysed using anion-exchange HPLC-ESI-MS/MS enabled improved chromatographic selectivity,
particularly for the less retained arsenosugar (glycerol sugar), facilitating confirmation of the presence of arsenosugars
in seaweed extracts and dialyzates. Using this approach, the presence of arsenobetaine in sea lettuce samples was also confirmed. 相似文献
116.
Prakash AS Smith MJ Kaabia Z Hurst G Yan C Sims M Bristow AW Stokes P Parker D Mosely JA 《Journal of the American Society for Mass Spectrometry》2012,23(5):850-857
LC ESI FTICR MS of a sample of cediranib identified this pharmaceutical target molecule plus an additional 10 compounds of
interest, all of which were less than 10% total ion current (TIC) peak intensity relative to cediranib. LC FTICR tandem mass
spectrometry using electron induced dissociation (EID) has been achieved and has proven to be the best way to generate useful
product ion information for all of these singly protonated molecules. Cediranib [M + H]+ fragmented by EID to give 29 product ions whereas QTOF-CID generated only one very intense product ion, and linear ion trap-CID,
which generated 10 product ions, but all with poor S/N. Twenty-six of the EID product ions were unique to this fragmentation
technique alone. By considering the complementary LC-EID and LC-CID data together, all 10 unknown compounds were structurally
characterized and proven to be analogous to cediranib. Of particular importance, EID produced unique product ion information
for one of the low level cediranib analogues that enabled full characterization of the molecule such that the presence of
an extra propylpyrrolidine group was discovered and proven to be located on the pyrrolidine ring of cediranib, solving an
analytical problem that could not be solved by collision induced dissociation (CID). Thus, it has been demonstrated that EID
is in harmony with the chromatography duty-cycle and the dynamic concentration range of synthetic compounds containing trace
impurities, providing crucial analytical information that cannot be obtained by more traditional methodologies. 相似文献
117.
Haywood J Stokes FA Less RJ McPartlin M Wheatley AE Wright DS 《Chemical communications (Cambridge, England)》2011,47(14):4120-4122
The reaction of chromocene, Cp(2)Cr, with dilithiated 2,3-diphenylguanidine [(PhNH)(2)C=NH = L(2)H(3)] gives the novel, quadruply-bonded tetraanion [Cr(2)(L(2)H)(4)](4-). 相似文献
118.
Goenaga-Infante H Kassam S Stokes E Hopley C Joel SP 《Analytical and bioanalytical chemistry》2011,399(5):1789-1797
The formation of intracellular dimethylselenide (DMSe) as a product of exposure of non-malignant (PBMCs) and lymphoma (RL
and DHL-4) cell lines to methylseleninic acid (MSA) at clinical levels is suggested here for the first time. This was achieved
by analysis of cell lysates by HPLC coupled to ICP-MS via APEX-Q nebulisation, enabling limits of detection for target methyl-Se
species which are up to 12-fold lower than those obtained with conventional nebulisation. Methyl-Se-glutathione (CH3Se-SG), although detected in lysates of cells exposed to MSA, was found to be a reaction product of MSA with glutathione.
This was confirmed by HPLC-ESI MS (MS) analysis of lysates of control cells (unexposed to Se) spiked with MSA. The MS/MS data
obtained by collision-induced dissociation fragmentation of the ion m/z 402 (for [M+H]+
80Se) were consistent with the presence of CH3Se-SG. Formation of DMSe was not detected by HPLC-ICP-MS in these spiked lysates, and it was found to require live cells in
cell media containing MSA. Interestingly, the ratio of DMSe to CH3Se-SG was significantly higher in lymphoma cells exposed to MSA in comparison to non-malignant cells. Moreover, maximum Se
uptake levels in lymphoma cell lines seemed to be reached much earlier (after 10 min of MSA exposure) than in non-malignant
cells. Finally, the GC-TOF-MS speciation data obtained for cell headspace suggested that the major Se species (dimethyldiselenide)
appeared to be present in lymphoma cell headspace at significantly higher concentrations than in non-malignant cell headspace
after only 10 min of exposure to MSA. Evidence for the presence of dimethylselenidesulfide in lymphoma cell headspace is also
provided for the first time. 相似文献
119.
Tim Stokes 《Algebra Universalis》2011,66(1-2):85-98
The agreement quasi-order on pairs of (partial) transformations on a set X is defined as follows: ${(f, g) \preceq (h, k)}$ if whenever f, g are defined and agree, so do h, k. We axiomatize function semigroups and monoids equipped with this quasi-order, thereby providing a generalisation of first projection quasi-ordered ${\cap}$ -semigroups of functions. As an application, axiomatizations are obtained for groups and inverse semigroups of injective functions equipped with the quasi-order of fix-set inclusion. All axiomatizations are finite. 相似文献
120.
Let A be a *-algebra. An additive mapping E : A → A is called a Jordan *-derivation if E(X2) = E(x)x*+xE(x) holds, for all x 6 A. These mappings have been extensively studied in the last 6 years by Bresar, Semrl, Vukman and Zalar because they are closely connected with the problem of representability of quadratic functionals by sesquilinear forms. This study was, however, always in the setting of associative rings. In the present paper we study Jordan *-derivations on the Cayley-Dickson algebra of octonions, which is not associative. Our first main result is that every Jordan *-derivation on the octonion algebra is of the form E(x)=ax*-xa. In the terminology of earlier papers this means that every Jordan *-derivation on the octonion algebra is inner. This generalizes the known fact that Jordan *-derivations on complex and quaternion algebras are inner. Our second main result is a representation theorem for quadratic functionals on octonion modules. Its proof uses the result mentioned above on Jordan *-derivations. 相似文献