Simple and efficient synthesis of 3,4-dihydro-2-pyridones via novel solid-supported aza-annulation

A diverse array of 3,4-dihydro-2-pyridones 13 were produced utilizing the unique properties of solid-supported reactions to both drive the reactions to completion and isolate the desired products. The pyridones were synthesized in high purity by a simple sequence of novel steps commencing from an acetophenone-functionalized resin. The para-substituted acetophenone 9 could be anchored to the resin through either a sulfonamide or a carboxamide linkage. The sulfonamide resin 9a, which gave the best results, was treated with several aryl aldehydes and ethoxide to give a variety of chalcones 10a-k in excellent yield (82-99%) upon TFA cleavage. Addition of either methyl or allyl malonate and DBU to 10a-k afforded smoothly the Michael adducts 11a-j (70-99%) which were subsequently cyclized in one step employing acetic acid as a catalyst and several diverse amines to give pure 3,4-dihydro-2-pyridones 13a-p in moderate to excellent yields (30-98%).     

A long-wavelength biolabeling reagent based on the oxonol fluorophore

A red fluorescent dye of the oxonol class, bis-[1-(carboxymethyl)barbituric acid-(5)]-pentamethinoxonol, has been synthesized and, in the form of the succinimidyl active ester, has been applied to antibody labeling for application to flow cytometry and to imaging of tissue sections. The new dye, named CMOX (for carboxymethyloxonol), shows maximum excitation at 583 nm and emission at 611 nm, with a quantum yield of 0.2 in aqueous buffer and methanol. Antibodies labeled with the new dye show favorable brightness, photostability, and low levels of nonspecific binding.     

Shape resonances in slow electron scattering by aromatic molecules. I. Anthraquinone derivatives

A series of anthraquinone (C(14)O(2)H(8)) derivatives has been studied by means of electron capture negative ion mass spectrometry (ECNI-MS), photoelectron spectroscopy (PES), and AM1 quantum chemical calculations. Mean lifetimes of molecular negative ions M(-.) (MNI) have been measured. The mechanism of long-lived MNI formation in the epithermal energy region of incident electrons has been investigated. A simple model of a molecule (a spherical potential well with the repulsive centrifugal term) has been applied for the analysis of the energy dependence of cross sections at the first stage of the electron capture process. It has been shown that a temporary resonance of MNI at the energy approximately 0.5 eV corresponds to a shape resonance with lifetime 1-2.10(-13) s in the f-partial wave (l = 3) of the incident electron. The next resonant state of MNI at the energy approximately 1.7 eV has been associated with the electron excited Feshbach resonance (whose parent state is a triplet npi* transition). In all cases the initial electron state of the MNI relaxes into the ground state by means of a radiationless transition, and the final state of the MNI is a nuclear excited resonance with a lifetime measurable on the mass spectrometry timescale. Copyright 1999 John Wiley & Sons, Ltd.     

A finite element formulation for global linear stability analysis of a nominally two‐dimensional base flow

A stabilized finite element method, to carry out the linear stability analysis of a two‐dimensional base flow to three‐dimensional perturbations that are periodic along span, is presented. The resulting equations for the time evolution of the disturbance requires a solution to the generalized eigenvalue problem. The analysis is global in nature and is also applicable to non‐parallel flows. Equal‐order‐interpolation functions for velocity and pressure are utilized. Stabilization terms are added to the Galerkin formulation to admit the use of equal‐order‐interpolation functions and to eliminate node‐to‐node oscillations that might arise in advection‐dominated flows. The proposed formulation is tested on two flow problems. First, the mode transitions in the circular Couette flow are investigated. Two scenarios are considered. In the first one, the outer cylinder is at rest, while the inner one spins. Two linearly unstable modes are identified. The primary mode is real and represents the axisymmetric Taylor vortices. The second mode is complex and consists of spiral vortices. For the counter‐rotating cylinders, the primary transition is via the appearance of spiral vortices. Excellent agreement with results from earlier studies is observed. The formulation is also utilized to investigate the parallel and oblique modes of vortex shedding past a cylinder for the Re = 100 flow. It is found that the flow is associated with a large number of unstable oblique shedding modes. The parallel mode of vortex shedding is a special case of this family of modes and is associated with the largest growth rate. Copyright © 2014 John Wiley & Sons, Ltd.     

Choosing fair lotteries to defeat the competition

We study the following game: each agent i chooses a lottery over nonnegative numbers whose expectation is equal to his budget b _i . The agent with the highest realized outcome wins (and agents only care about winning). This game is motivated by various real-world settings where agents each choose a gamble and the primary goal is to come out ahead. Such settings include patent races, stock market competitions, and R&D tournaments. We show that there is a unique symmetric equilibrium when budgets are equal. We proceed to study and solve extensions, including settings where agents choose their budgets (at a cost) and where budgets are private information.     

False-name-proof voting with costs over two alternatives

In open, anonymous settings such as the Internet, agents can participate in a mechanism multiple times under different identities. A mechanism is false-name-proof if no agent ever benefits from participating more than once. Unfortunately, the design of false-name-proof mechanisms has been hindered by a variety of negative results. In this paper, we show how some of these negative results can be circumvented by making the realistic assumption that obtaining additional identities comes at a (potentially small) cost. We consider arbitrary such costs and apply our results within the context of a voting model with two alternatives.     

Refraction and absorption of light in bacterial suspensions

Summary The apparent average refractive indices of three types of microorganism in liquid suspension have been estimated by two methods. In the first, the refractive index of the aqueous suspension is measured in an interferometer, the bacterial cell volume fraction is estimated from the dilution of an added inert solute, and the refractive index of the disperse phase is calculated with the aid of a mixture rule. In the second method, optical density spectra of suspensions in several concentrated solutions of nonpenetrating solutes are measured as a function of the refractive index,n ₁, of the solution. The value ofn ₁ when the optical density,E, has its smallest value is equated to the average cell refractive index and the constants of the parabolaE (n ₁) are related to the heterogeneity of the cell population in respect to refractive index. The preliminary results obtained by the two methods are in satisfactory agreement and are consistent with the specific refractive increments of protein and nucleic acid and their concentrations in the cell. It is pointed out that measurements of optical density spectra can also give useful information concerning the number and size of cells in a suspension and their optical dispersion constants. To obtain such information, however, a spectrophotometer specially designed to exclude forward-scattered light must be used and an acceptable theory must be available. Finally, the apparent spectral absorption of clarified cell suspensions is presented and compared with spectra obtained by other methods. It is pointed out that because of refractive heterodispersity even clarified suspensions are turbid, so that this method does not provide a completely satisfactory technique for cell spectrophotometry.

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Zusammenfassung Es wurde der scheinbare mittlere Brechungsindex von 3 Typen von Mikroorganismen in flüssiger Suspension nach zwei Methoden abgeschätzt:Bei der ersten Methode wird der Brechungsindex der bisherigen Lösung in einem Interferometer gemessen. Die Volumenkonzentration der Bakterienzellen wird aus der Verdünnung mit einer zugesetzten inerten Komponente abgeschätzt. Der Brechungsindex der dispersen Phase wird mit Hilfe der Mischungsregel berechnet.Nach der 2. Methode werden Spektren der optischen Dichte der Suspensionen in verschiedenen konzentrierten Lösungen von nicht-mischbarer 2. Komponente als Funktion des Brechungsindexn ₁ gemessen. Dieser Brechungsindexn ₁ hat seinen kleinsten Wert, wenn die optische DichteE dem mittleren Brechungsindex der Zellen gleich ist, und die Konstanten der ParabelnE (n ₁) stehen in Beziehung zur Heterogenität der Zellverteilung in Bezug auf den Brechungsindex.Die vorläufig nach den beiden Methoden erhaltenen Ergebnisse stimmen befriedigend überein und sind konsistent mit den spezifischen Refractionsinkrementen von Eiweiß- und Nukleinsäure und deren Konzentrationen in der Zelle. Es sei betont, daß Messungen der optischen Dichtespektren auch gute Information über Zahl und Größe der Zellen in einer Suspension und über deren optische Dispersionskonstanten geben können. Um diese Information zu erhalten, muß jedoch speziell ein Spektrometer gebaut werden, das gestattet, das vorwärtsgestreute Licht auszuschließen. Außerdem muß eine akzeptable Theorie vorhanden sein. Schließlich wird die scheinbare Spektralabsorption von geklärten Zellsuspensionen dargelegt und mit den Spektren, die nach anderen Methoden erhalten werden, verglichen. Es ist ausgeführt, daß wegen der Heterodispersität auch geklärte Suspensionen streuen, so daß diese Methode keine vollständig befriedigende Technik für Zellspektrometrie darstellt.