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131.
Béatrice Nicolaï Nathalie Mahé René Céolin Ivo B. Rietveld Maria Barrio Josep-Lluis Tamarit 《Structural chemistry》2011,22(3):649-659
l-Tyrosine alkyl esters are used as prodrugs for l-tyrosine. Although prodrugs are often designed for their behavior in solution, understanding their solid-state properties is the first step in mastering drug delivery. The crystal structure of l-tyrosine methyl ester has been determined and compared to published structures of l-tyrosine and its ethyl and n-butyl esters. It is almost isostructural with the other esters: it crystallizes in the orthorhombic chiral space group P212121, a = 5.7634(15) Å, b = 12.111(2) Å, c = 14.3713(19) Å, V = 1003.1(4) Å3 with Z′ = 1. Their main packing motif is a C(9) infinite hydrogen-bond chain, but the conformation of l-tyrosine methyl ester is different from the other two: eclipsed versus U-shaped, respectively. The published structure of the ethyl ester, which was incomplete, has been confirmed by X-ray powder diffraction data. Because l-tyrosine methyl ester is very stable (28 years stored at room temperature), and its hydrolysis rate is relatively low, it should be one of the better prodrugs among the alkyl esters of tyrosine. 相似文献
132.
Michael J. Ingleson Dr. Jorge Perez Barrio John Bacsa Dr. Alexander Steiner Dr. George R. Darling Dr. James T. A. Jones Yaroslav Z. Khimyak Dr. Matthew J. Rosseinsky Prof. 《Angewandte Chemie (International ed. in English)》2009,48(11):2012-2016
In close quarters : When confined in a metal–organic framework, magnesium borohydride reacts with arenes by a hydroboration pathway (see scheme), in contrast to its reactivity under analogous homogeneous solution‐phase conditions. Framework‐imposed organization of the reactive groups is required, which is achieved by a combination of the metal coordination and two hydrogen bonds.
133.
Maclean D Zhu J Chen M Hale R Satymurthy N Barrio JR 《Journal of the American Chemical Society》2003,125(34):10168-10169
A novel synthetic stratetegy for compounds labeled with the positron-emitting isotope carbon-11 is described. The use of precursors attached to a solid support via safety-catch linkers allows selective release of radiolabeled material, leaving unreacted precursor attached to the support. Two different linkers demonstrate the application to the preparation of radiolabeled N-alkyl tertiary amines and N-alkylsulfonamides. This technique is expected to lead to more widespread use of positron emission tomography for the in vivo analysis of compound behavior. 相似文献
134.
We present a unified rounding error bound for polynomial evaluation. The bound presented here takes the same general form for the evaluation of a polynomial written in any polynomial basis when the evaluation algorithm can be expressed as a linear recurrence or a first-order linear matrix recurrence relation. Examples of these situations are: Horner's algorithm in the evaluation of power series, Clenshaw's and Forsythe's algorithms in the evaluation of orthogonal polynomial series, de-Casteljau's algorithm for Bernstein polynomial series, the modification of Clenshaw's algorithms in the evaluation of Szeg polynomial series, and so on. 相似文献
135.
An electrochemical sensor for the determination of serotonin in urine was prepared using Ni(II)-phthalocyanine and Nafion to modify the surface of a 4 mm length carbon fiber microelectrode. The resultant sensor was found to improve the response towards this neuronal amine versus the microelectrode without the polymer films. Different polymerization conditions, as well as different conditioning solutions and buffer systems, were investigated in order to optimize the response of the electrodes. Square wave voltammetry (SWV) is proposed as a direct method for determination of serotonin in human urine, after a solid-liquid extraction process. The proposed method enables a detection limit for serotonin of 0.80 +/- 0.04 microgram L-1 to be achieved at a reduction potential of 0.35 V, with an overall prediction error of 2.2% and recoveries of 93%. 相似文献
136.
Alavi-Harati A Alexopoulos T Arenton M Arisaka K Averitte S Barbosa RF Barker AR Barrio M Bellantoni L Bellavance A Belz J Ben-David R Bergman DR Blucher E Bock GJ Bown C Bright S Cheu E Childress S Coleman R Corcoran MD Corti G Cox B Crisler MB Erwin AR Ford R Glazov A Golossanov A Graham G Graham J Hagan K Halkiadakis E Hamm J Hanagaki K Hidaka S Hsiung YB Jejer V Jensen DA Kessler R Kobrak HG LaDue J Lath A Ledovskoy A McBride PL Mikelsons P Monnier E Nakaya T Nelson KS Nguyen H O'Dell V 《Physical review letters》2001,87(13):132001
We present the first measurement of the form factor ratios g(1)/f(1) (direct axial vector to vector), g(2)/f(1) (second class current), and f(2)/f(1) (weak magnetism) for the decay Xi(0)-->Sigma(+)e(-)nu macro(e) using the KTeV (E799) beam line and detector at Fermilab. From the Sigma(+) polarization measured with the decay Sigma(+)-->p pi(0) and the e(-)-nu; correlation, we measure g(1)/f(1) to be 1.32+/-(0.21)(0.17)(stat)+/-0.05(syst), assuming the SU(3)(f) (flavor) values for g(2)/f(1) and f(2)/f(1). Our results are all consistent with exact SU(3)(f) symmetry. 相似文献
137.
Alavi-Harati A Alexopoulos T Arenton M Arisaka K Averitte S Barbosa RF Barker AR Barrio M Bellantoni L Bellavance A Belz J Ben-David R Bergman DR Blucher E Bock GJ Bown C Bright S Cheu E Childress S Coleman R Corcoran MD Corti G Cox B Crisler MB Erwin AR Ford R Glazov A Golossanov A Graham G Graham J Hagan K Halkiadakis E Hamm J Hanagaki K Hidaka S Hsiung YB Jejer V Jensen DA Kessler R Kobrak HG LaDue J Lath A Ledovskoy A McBride PL Mikelsons P Monnier E Nakaya T Nelson KS Nguyen H O'Dell V 《Physical review letters》2001,87(11):111802
We have collected a 43 event sample of the decay K(L)-->e(+)e(-)mu(+)mu(-) with negligible backgrounds and measured its branching ratio to be (2.62+/-0.40+/-0.17)x10(-9). We see no evidence for CP violation in this decay. In addition, we set the 90% confidence upper limit on the combined branching ratios for the lepton flavor violating decays K(L)-->e(+/-)e(+/-)mu(-/+)mu(-/+) at B(K(L)-->e(+/-)e(+/-)mu(-/+)mu(-/+))< or =1.23x10(-10), assuming a uniform phase space distribution. 相似文献
138.
M. Barrio J. Font D. O. López J. Muntasell J. Ll. Tamarit 《Journal of Thermal Analysis and Calorimetry》1991,37(2):397-410
In this work we give the specific heat values of different plastic crystals, determined by AC calorimetry are presented. The heat capacity evolution during different types of solid transitions in these molecular crystals is compared. The influence of the kinetic of the transformation on the shape of this evolution can be seen. 相似文献
139.
Alavi-Harati A Alexopoulos T Arenton M Arisaka K Averitte S Barbosa RF Barker AR Barrio M Bellantoni L Bellavance A Belz J Bergman DR Blucher E Bock GJ Bown C Bright S Cheu E Childress S Coleman R Corcoran MD Corti G Cox B Cunha A Erwin AR Ford R Glazov A Golossanov A Graham G Graham J Halkiadakis E Hamm J Hanagaki K Hidaka S Hsiung YB Jejer V Jensen DA Kessler R Kobrak HG LaDue J Lath A Ledovskoy A McBride PL Medvigy D Mikelsons P Monnier E Nakaya T Nelson KS Nguyen H O'Dell V Pordes R 《Physical review letters》2002,89(7):072001
We use K(L)'s in the 100-200 GeV energy range to produce 147 candidate events of the axial vector pair K1(1270)-K1(1400) in the nuclear Coulomb field of a Pb target and determine the radiative widths Gamma(K1(1400)-->K0+gamma)=280.8+/-23.2(stat)+/-40.4(syst) keV and Gamma(K1(1270)-->K0+gamma)=73.2+/-6.1(stat)+/-28.3(syst) keV. These first measurements appear to be lower than the quark-model predictions. We also place upper limits on the radiative widths for K(*)(1410) and K(*)(2)(1430) and find that the latter is vanishingly small in accord with SU(3) invariance in the naive quark model. 相似文献
140.
Alavi-Harati A Alexopoulos T Arenton M Arisaka K Averitte S Barbosa RF Barker AR Barrio M Bellantoni L Bellavance A Belz J Ben-David R Bergman DR Blucher E Bock GJ Bown C Bright S Cheu E Childress S Coleman R Corcoran MD Corti G Cox B Crisler MB Erwin AR Ford R Glazov A Golossanov A Graham G Graham J Hagan K Halkiadakis E Hamm J Hanagaki K Hidaka S Hsiung YB Jejer V Jensen DA Kessler R Kobrak HG LaDue J Lath A Ledovskoy A McBride PL Mikelsons P Monnier E Nakaya T Nelson KS Nguyen H O'Dell V 《Physical review letters》2002,88(18):181601
We present a measurement of the charge asymmetry delta(L) in the mode K(L)-->pi(+/-)e(-/+)nu based on 298 x 10(6) analyzed decays. We measure a value of delta(L) = [3322+/-58(stat)+/-47(syst)]x10(-6), in good agreement with previous measurements and 2.4 times more precise than the current best published result. The result is used to place more stringent limits on CPT and DeltaS = DeltaQ violation in the neutral kaon system. 相似文献