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501.
[reaction: see text] An efficient synthesis of a terminal alkyne derived from d-biotin was developed to provide an alternative for carboxyl-based biotinylation. This approach was illustrated by the preparation of alkyne- and alkene-linked phenylalanine derivatives using palladium-catalyzed Sonogashira and Oh methodology. (Strept)avidin binding was observed using soluble and immobilized receptors. These results demonstrate the applicability of carbon-linked biotin derivatives for use in affinity-based purification and bioanalytical applications. 相似文献
502.
Ramesh C Bryant B Nayak T Revankar CM Anderson T Carlson KE Katzenellenbogen JA Sklar LA Norenberg JP Prossnitz ER Arterburn JB 《Journal of the American Chemical Society》2006,128(45):14476-14477
We describe a new structural class of neutral tridentate pyridin-2-yl hydrazine chelates for labeling with tricarbonyl Re/99mTc(I) under aqueous conditions and investigate the receptor binding of synthetic estradiol derivatives with the novel G-protein-coupled receptor GPR30 and estrogen receptors ERalpha/beta. The steroid linkage affected the affinity and selectivity of estrogen binding with these receptors. Fluorescence assays based on calcium signaling demonstrate that membrane-permeable chelates 2 and 3 interact with the receptors in whole cells. These results suggest that in vitro assays will facilitate the development of targeted imaging agents for intracellular receptors and the feasibility of targeting GPR30 and ERalpha/beta for diagnostic tumor imaging. 相似文献
503.
504.
Lindner's conjecture that any partial Steiner triple system of order u can be embedded in a Steiner triple system of order v if and is proved. © 2008 Wiley Periodicals, Inc. J Combin Designs 17: 63–89, 2009 相似文献
505.
Jieying Jing Yu Zhang Jiangyu Liang Qingbo Zhang Erika Bryant Carolina Avendano Vicki L. Colvin Yiding Wang Wenying Li William W. Yu 《Journal of nanoparticle research》2012,14(4):1-8
A convenient method for preparation of pure and doped yttrium oxide was developed, which is based on irradiation of solutions containing yttrium nitrate and ammonium formate with UV light or accelerated electrons. Solid phase formed under irradiation was consequently calcined at 500?°C or higher temperatures to obtain nanocrystalline yttrium oxide. Addition of small amount of cerium(III) or europium(III) nitrates to irradiated solutions resulted in doping of yttrium oxide with Ce(III) or Eu(III) ions. Under both types of irradiation, the method yields material with high specific surface area, consisting of spherical nanoparticles 25?C100?nm in diameter depending on preparative conditions and post-radiation treatment and with narrow size distribution. In the doped oxides (Y2O3:Ce or Y2O3:Eu), radioluminescence spectra typical for Ce3+ or Eu3+ doped oxide structures were observed. 相似文献
506.
Measurements of the electrophoretic mobility (u
E) of particles of colloidal α-alumina were made as a function of pH, electrolyte concentration and electrolyte type (NaCl,
NaNO3 and KCl) using two similar instrumental techniques. Significant differences (50% or less) in the values of u
E of particles in NaCl were obtained from the two instruments; however, the isoelectric points (IEPs) (the pH at which u
E=0), estimated from the two sets of measurements, occurred at 7.5 ± 0.3 and 7.8 ± 0.05 and were not significantly different.
The latter estimate corresponds with those for particles in KCl and NaNO3 of 8.05 ± 0.11 and 7.95 ± 0.18, respectively, made using the same instrument and indicate that the IEP was a weak function
of electrolyte type. When cations acted as counterions (pH > IEP), the absolute magnitudes and the ranges of u
E with electrolyte concentration were found to be significantly less than when anions acted as counterions (IEP > pH). Estimates
of the zeta potential (ζ), made using various procedures, showed variations of up to 25% at low ratios of electrical-double-layer
thickness (κ
−1) to particle radius (a) (κa∼10) and were of a similar scale to differences in u
E, but no significant variations (95% confidence) in ζ were obtained at high values (κa∼200).
Received: 12 July 2000 Accepted: 17 October 2000 相似文献
507.
Robert I. Bryant 《Results in Mathematics》2001,40(1-4):88-121
The problem of immersing a simply connected surface with a prescribed shape operator is discussed. It is shown that, aside from some special degenerate cases, such as when the shape operator can be realized by a surface with one family of principal curves being geodesic, the space of such realizations is a convex set in an affine space of dimension at most 3. The cases where this maximum dimension of realizability is achieved are analyzed and it is found that there are two such families of shape operators, one depending essentially on three arbitrary functions of one variable and another depending essentially on two arbitrary functions of one variable. The space of realizations is discussed in each case, along with some of their remarkable geometric properties. Several explicit examples are constructed. 相似文献
508.
509.
Oliver Wieder Mlaine Kuenemann Marcus Wieder Thomas Seidel Christophe Meyer Sharon D. Bryant Thierry Langer 《Molecules (Basel, Switzerland)》2021,26(20)
The accurate prediction of molecular properties, such as lipophilicity and aqueous solubility, are of great importance and pose challenges in several stages of the drug discovery pipeline. Machine learning methods, such as graph-based neural networks (GNNs), have shown exceptionally good performance in predicting these properties. In this work, we introduce a novel GNN architecture, called directed edge graph isomorphism network (D-GIN). It is composed of two distinct sub-architectures (D-MPNN, GIN) and achieves an improvement in accuracy over its sub-architectures employing various learning, and featurization strategies. We argue that combining models with different key aspects help make graph neural networks deeper and simultaneously increase their predictive power. Furthermore, we address current limitations in assessment of deep-learning models, namely, comparison of single training run performance metrics, and offer a more robust solution. 相似文献
510.
Bryant C. Nelson Gary F. Rockwell Thomas Campfield Patrick OGrady Rose M. Hernandez Stephen A. Wise 《Analytica chimica acta》2000,410(1-2):1-10
A capillary electrophoretic (CE) assay for oxalate has been applied to the quantitative determination of free oxalate in amniotic fluid. Indirect absorbance detection of oxalate is accomplished with a chromate-based background electrolyte modified with ethylenediaminetetraacetic acid (EDTA). Detection interference due to the presence of high levels (≈4 mg/ml) of inorganic chloride is eliminated through a direct sample clean-up procedure based on cation (Ag+-form) resins. Separation interference from amniotic fluid proteins is prevented through the use of a simple aqueous-based dilution procedure. This method for the determination of oxalate in amniotic fluid provides precision of ≈5% relative standard deviation (RSD). Within-day precisions for the oxalate response and migration time are better than 3% RSD and 1% RSD, respectively. Between-day precisions for the oxalate response and migration time are better than 6% RSD and 3% RSD, respectively. The analytical recovery of oxalate (1000 ng/ml) spiked into amniotic fluid was better than 96%. The limit of detection (LOD) for the method is ≈100 ng/ml oxalate. This method also shows promising results for the determination of oxalate in human blood plasma samples. 相似文献