Simultaneous determination of tetrahydro-β-carbolines and β-carbolines

Summary Reversed-phase ion-pair HPLC with fluorimetric detectors connected in series was studied for the simultaneous determination of two tetrahydro-720lx72111293280/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-carbolines and two 720lx72111293280/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-carbolines. After additon of internal standards the samples were reacted with fluorescamine, and then subjected to serial extractions to remove their precursor (tryptamine) from the analytical system. This treatment not only suppressed the artefactual formation of tetrahydro-720lx72111293280/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-carbolines and 720lx72111293280/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-carbolines during analysis, but also effectively purified them. Under optimum conditions, using trifluoroacetic acid as counter ion, all analytes were separated within 14 min and without major interfering peaks. The quantitative ranges were 0.25–80.0 ng mL^–1 for both tetrahydro-720lx72111293280/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-carbolines and 0.1–30.0 ng mL^–1 for both 720lx72111293280/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-carbolines. Replicate spiking experiments showed that recovery from most of the samples tested was over 90% and the relative standard deviation ranged from 0.7 to 10.4% within and between assays. The proposed method was applicable to various materials such as soy sauce, vinegar, ketchup, tabasco, beer, wine, sake, whisky, brandy, cows' milk, coffee, cocoa, cheese, cigarette smoke and urine.     

论HDTV图像的显示模式及电视线

从HDTV标准入手,运用电视原理知识,对HDTV图像的显示模式、电视线、分辨率等主要内容进行了论述,以提高业内人士对HDTV相关知识的了解。     

A convergent synthesis of the immunosuppressant FTY720 employing aqueous Wittig chemistry

A short, convergent synthesis of the immunosuppressant FTY720 is described involving the use of 4-hydroxymethylbenzaldehyde as a pivotal intermediate. A double Wittig strategy was developed to connect this dual-functional aldehyde with an alkyl-tether and to a readily available TRIS-derivative leading to an efficient synthesis of the target molecule.     

Direct mono-phosphorylation of 1,3-diols. A synthesis of FTY720-phosphate

A novel method for selective and direct phosphorylation of various 1,3-diols using silver(I) oxide, tetrabenzyl pyrophosphate (TBPP), and tetrahexylammonium iodide affording mono-phosphates was developed. We applied the present method to the synthesis of FTY720-phosphate.     

On the geometry of Nash equilibria and correlated equilibria

It is well known that the set of correlated equilibrium distributions of an n-player noncooperative game is a convex polytope that includes all the Nash equilibrium distributions. We demonstrate an elementary yet surprising result: the Nash equilibria all lie on the boundary of the polytope.We are grateful to Francoise Forges, Dan Arce, the editors, and several anonymous referees for helpful comments. This research was supported by the National Science Foundation under grant 98–09225 and by the Fuqua School of Business.The use of correlated mixed strategies in 2-player games was discussed by Raiffa (1951), who noted: it is a useful concept since it serves to convexify certain regions [of expected payoffs] in the Euclidean plane. (p. 8)Received: April 2002 / Revised: November 2003     

The effect of mechanical grinding on the formation and crystallinity changes of the inclusion complex of acetaminophen andβ-cyclodextrin

The effect of mechanical grinding on the physicochemical properties of acetaminophen in the presence of three additives,720k5q828mh32/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">- or720k5q828mh32/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin and microcrystalline cellulose, was studied by using TLC, powder X-ray diffraction analysis, infrared spectroscopy and differential scanning calorimetry. The results indicate that the crystallinity of physical mixtures of acetaminophen and the described additives decreased with increased grinding time and formed an amorphous state when mixtures containing720k5q828mh32/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">- or720k5q828mh32/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin were ground with acetaminophen. We also found that the acetaminophen molecules could be included step-by-step into the cavity of720k5q828mh32/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin molecules and formed an amorphous inclusion complex.720k5q828mh32/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-Cyclodextrin and microcrystalline cellulose did not form an inclusion complex with acetaminophen, but acted only to decrease the crystallinity of the ground mixtures. The mechanical grinding efficiency for acetaminophen was improved in the order of720k5q828mh32/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin 720k5q828mh32/xxlarge8811.gif" alt="Gt" align="MIDDLE" BORDER="0">720k5q828mh32/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-cyclodextrin > microcrystalline cellulose.This paper is part XI of 720k5q828mh32/xxlarge8216.gif" alt="lsquo" align="BASELINE" BORDER="0">Drug Interaction in Pharmaceutical Formulations.     

Synthesis of fluorinated analogues of the immunosuppressive drug FTY720

Four fluorinated derivatives of the immunosuppressive drug FTY720 were synthesized by a convergent strategy, using the Sonogashira coupling as the key reaction to assemble the two major fragments.     

Short proofs of summation and transformation formulas for basic hypergeometric series

We show that several terminating summation and transformation formulas for basic hypergeometric series can be proved in a straightforward way. Along the same line, new finite forms of Jacobi's triple product identity and Watson's quintuple product identity are also proved.