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41.
Rosner JL Alexander JP Cassel DG Duboscq JE Ehrlich R Fields L Gibbons L Gray R Gray SW Hartill DL Heltsley BK Hertz D Jones CD Kandaswamy J Kreinick DL Kuznetsov VE Mahlke-Krüger H Mohapatra D Onyisi PU Patterson JR Peterson D Riley D Ryd A Sadoff AJ Shi X Stroiney S Sun WM Wilksen T Athar SB Patel R Yelton J Rubin P Eisenstein BI Karliner I Mehrabyan S Lowrey N Selen M White EJ Wiss J Mitchell RE Shepherd MR Besson D Pedlar TK Cronin-Hennessy D Gao KY Hietala J Kubota Y Klein T Lang BW 《Physical review letters》2008,100(22):221801
We exploit the quantum coherence between pair-produced D0 and D[over]0 in psi(3770) decays to study charm mixing, which is characterized by the parameters x and y, and to make a first determination of the relative strong phase delta between D0-->K+pi- and D[over]0-->K+pi-. Using 281 pb(-1) of e+e- collision data collected with the CLEO-c detector at Ecm=3.77 GeV, as well as branching fraction input and time-integrated measurements of RM identical with (x2 + y2)/2 and RWS identical with Gamma(D0-->K+pi-)/Gamma(D[over]0-->K+pi-) from other experiments, we find cosdelta=1.03(-0.17)(+0.31)+/-0.06, where the uncertainties are statistical and systematic, respectively. By further including other mixing parameter measurements, we obtain an alternate measurement of cosdelta=1.10+/-0.35+/-0.07, as well as x sindelta=(4.4(-1.8)(+2.7)+/-2.9)x10(-3) and delta=(22(-12-11)(+11+9)) degrees . 相似文献
42.
A novel and convenient method for the synthesis of C-terminally branched collagen-model peptides has been achieved using tricine (N-[tris(hydroxymethyl)methyl]glycine) as a branching scaffold and 1,2-diaminoethane or 1,4-diaminobutane as a linker. The peptide sequence was incorporated directly onto the linker and scaffold during solid-phase synthesis without additional manipulations. The resulting branched triple-helical peptides exhibited comparable thermal stabilities to the parent, unbranched sequence, and served as substrates for matrix metalloproteinase-1 (MMP-1). The tricine-based branch reported herein represents the simplest synthetic scaffold for the convenient synthesis of covalently linked homomeric collagen-model triple-helical peptides. 相似文献
43.
Jerry Fields Xiang Ouyang Steven R. Herron Katherine A. Kantardjieff Ali Jabalameli Frank A. Gomez 《Journal of chemical crystallography》2007,37(1):55-62
The synthesis and molecular structure of the novel 1-[ferrocenyl(hydroxy)methyl]-1,7-dicarba-closo-dodecaborane (1) is described. Compound 1 was synthesized from reaction of m-carborane and ferrocene carboxaldehyde using n-butyllithium (n-BuLi) or tetrabutylammonium fluoride (TBAF) in THF in 45% and 36% yield, respectively. Compound 1 consists of a ferrocene molecule tethered to m-carborane through a methylhydroxy bridge. The crystal structure of 1 was determined by single crystal X-ray diffraction analysis. Crystal data: 1 [Fe(C5H5)(C5H4-CH2O-1,7-C2B10H12)], formula weight = 359.17, crystallized in orthorhombic system, space group Pna2
1
with a=19.698(4) ?, b=10.709(2) ?, c=8.520(2) ?, and V=1797.3(7) ?3 and Z=4. Refined to R
1=0.043 for 4124 observed reflections with I/σ>2σ(I). The compound was crystallized as racemic twins in a ratio of 73(2)/27(2). The unsubstituted Cp ring was disordered and
modeled as two conformations in a 53(3)/47(3) ratio. Intermolecular hydrogen bonding was observed from the hydrogen of the
meta-carbon on the carborane cluster towards the hydroxyl oxygen. 相似文献
44.
Synthesis of diporphyrins via palladium-catalyzed C-O bond formation: effective access to chiral diporphyrins 总被引:1,自引:0,他引:1
Gao GY Ruppel JV Fields KB Xu X Chen Y Zhang XP 《The Journal of organic chemistry》2008,73(13):4855-4858
Diporphyrins can be efficiently synthesized from bromoporphyrin precursors via palladium-catalyzed C-O bond formation. The synthetic methodology is general and can be applied to various diols, forming a series of homo-diporphyrins containing different types of spacers in high to excellent yields. Chiral diporphyrins can be readily constructed through the use of optically active diols. A similar strategy allows access to hetero-diporphyrins and triporphyrins, including free-base and metalloporphyrin hetero dimers. 相似文献
45.
Rezler EM Khan DR Lauer-Fields J Cudic M Baronas-Lowell D Fields GB 《Journal of the American Chemical Society》2007,129(16):4961-4972
Nanotechnology-based drug delivery systems (nanoDDSs) have seen recent popularity due to their favorable physical, chemical, and biological properties, and great efforts have been made to target nanoDDSs to specific cellular receptors. CD44/chondroitin sulfate proteoglycan (CSPG) is among the receptors overexpressed in metastatic melanoma, and the sequence to which it binds within the type IV collagen triple-helix has been identified. A triple-helical "peptide-amphiphile" (alpha1(IV)1263-1277 PA), which binds CD44/CSPG, has been constructed and incorporated into liposomes of differing lipid compositions. Liposomes containing distearoyl phosphatidylcholine (DSPC) as the major bilayer component, in combination with distearoyl phosphatidylglycerol (DSPG) and cholesterol, were more stable than analogous liposomes containing dipalmitoyl phosphatidylcholine (DPPC) instead of DSPC. When dilauroyl phosphatidylcholine (DLPC):DSPG:cholesterol liposomes were prepared, monotectic behavior was observed. The presence of the alpha1(IV)1263-1277 PA conferred greater stability to the DPPC liposomal systems and did not affect the stability of the DSPC liposomes. A positive correlation was observed for cellular fluorophore delivery by the alpha1(IV)1263-1277 PA liposomes and CD44/CSPG receptor content in metastatic melanoma and fibroblast cell lines. Conversely, nontargeted liposomes delivered minimal fluorophore to these cells regardless of the CD44/CSPG receptor content. When metastatic melanoma cells and fibroblasts were treated with exogeneous alpha1(IV)1263-1277, prior to incubation with alpha1(IV)1263-1277 PA liposomes, to potentially disrupt receptor/liposome interactions, a dose-dependent decrease in the amount of fluorophore delivered was observed. Overall, our results suggest that PA-targeted liposomes can be constructed and rationally fine-tuned for drug delivery applications based on lipid composition. The selectivity of alpha1(IV)1263-1277 PA liposomes for CD44/CSPG-containing cells represents a targeted-nanoDDS with potential for further development and application. 相似文献
46.
This study compared two methods of monitoring radioisotopes in high-performance liquid chromatographic eluates (on-line radioactivity detector versus fraction collection and counting). Testing was accomplished by pumping solutions of tritiated water in acetonitrile--water mixture through the detector or to the fraction collector. At most solvent compositions, the detector's counting efficiency and detection limits were poorer than those of the scintillation counter. However, the reproducibility of the detector data was superior at acetonitrile concentrations of less than 50%. This was attributed to the difficulty in collecting fractions of small equal volumes at the lower organic solvent concentrations in short time intervals. We conclude that on-line monitoring with homogeneous detection is the preferred method for detecting radiolabeled compounds in high-performance liquid chromatographic eluates. 相似文献
47.
L.R. Cormell M.W. Arenton H.F. Chen M. Corcoran W.R. Ditzler M. Dris A.R. Erwin T. Fields J. Fleischman E. Gardella M. Harrison M.A. Hasan K. Johns A. Kanofsky W. Kononenko C.E. Kuehn H.E. Miettinen B.T. Yost 《Physics letters. [Part B]》1985,150(4):322-326
In an experiment performed at Fermilab we have studied the production of high pt hadron jets from 400 GeV/c pp interactions. A large solid-angle, towered calorimeter was used to trigger and reconstruct the jet events. We report results for inclusive single-jet production and compare those results with QCD predictions and results obtained at the ISR and the SPS Collider. 相似文献
48.
T. L. Fields Yang-i Lin J. D. Warren S. A. Lang 《Journal of heterocyclic chemistry》1988,25(6):1917-1918
Bisguanylhydrazones of anthracene-9,10-dicarboxaldehyde have demonstrated excellent antitumor activity. Heterocyclic analogs were synthesized in an effort to expand or modify the activity profile. 相似文献
49.
50.
Longley NP Bode CR Border PM Courant H DeMuth DM Gray RN Johns K Kasahara SM Lowe MJ Marshak ML Miller WH Mualem L Peterson EA Roback DM Ruddick K Schmid DJ Schub MH Shupe MA Vassiliev V Villaume G Werkema SJ Ayres DS Fields TH Gallagher HM Goodman MC Lopez FV May EN Price LE Seidlein RV Thron JL Trost H Uretsky JL Allison WW Barr GD Brooks CB Cobb JH Giller GL Stassinakis A Thomson MA West N Wielgosz U Alner GJ Cockerill DJ Cotton RJ Garcia-Garcia C Litchfield PJ Pearce GF Ewen B Kafka T 《Physical review D: Particles and fields》1995,52(5):2760-2765