Oscillation theorems for nth order nonlinear functional differential equations

In the modern geometric approach partial differential equations are cast into equivalent ideals of differential forms. The invariance of forms under transformation groups is used for constructing invariant solutions by geometric methods. In the present paper the concept of partially invariant solutions introduced earlier by Ovsjannikov is studied in order to obtain geometric methods for partially invariant solutions too.     

Existence theorems for nonlinear functional differential equations of neutral type

Conditions are found upon satisfaction of which the differential equation

Blends of amphiphilic trisilanolisobutyl-POSS and phosphine oxide substituted poly(dimethylsiloxane) at the air/water interface

Mixtures of a polyhedral oligomeric silsesquioxane, trisilanolisobutyl-POSS, and a polar silicone, poly(dimethyl-co-methylvinyl-co-methyl, 2-diphenyl phosphine oxide ethyl) siloxane (PDMS-PO), spread as Langmuir monolayers at the air/water interface are used to examine the surface phase behavior and aggregation of trisilanolisobutyl-POSS as a function of silicone composition. Analyses of the surface pressure-area per monomer (Pi-A) isotherms in terms of the collapse pressures and excess Gibbs free energies of mixing indicate the monolayers form slightly negative deviation mixtures. Direct observations of surface morphology with Brewster angle microscopy in the collapsed regime reveal that the governing factor for aggregation is the collapse Pi of the component with a stronger affinity for water. In trisilanolisobutyl-POSS/PDMS-PO blends, POSS aggregates as discrete domains and does not coalesce into larger aggregates or networklike structures for <80 wt % POSS, a feature that is vastly different from a previous study of POSS blended with regular poly(dimethylsiloxane).     

Synthesis of picolinohydrazides and their evaluation as ligands in the zinc-catalyzed hydrosilylation of ketones

A set of picolinohydrazides was prepared by reaction between hydrazines and either 2-picolinic acid or ethyl pyridine-2-carboxylate, and characterized. These molecules were evaluated as ligands in the zinc-catalyzed hydrosilylation of ketones. Thus, several aromatic and aliphatic ketones were successfully reduced by diethoxymethylsilane as the hydride source in the presence of a catalytic system made of diethylzinc combined in situ to the picolinohydrazides described herein.     

A numerical solution of the nonlinear wave resistance problem for simple shaped submerged bodies

Summary This paper presents a numerical method to compute the nonlinear wave resistance of a body, submerged in a free stream of infinite depth. The solution is given in the form of a potential of single layer and the nonlinear boundary conditions on the free surface are fulfilled by means of an iterative procedure. Results are shown for the 2-D case of an elliptical cylinder and for the 3-D case of prolate spheroids. All the presented results are discussed taking into account some experimental data and analytical solutions available in literature.

---

Sommario In questo lavoro viene sviluppato un metodo per il calcolo della resistenza ondosa di corpi immersi bidimensionali e tridimensionali, tenendo conto della non linearità delle condizioni sulla superficie libera. La soluzione cercata è posta nella forma di potenziale di strato semplice e la non linearità presente nelle condizioni al contorno viene trattata con un procedimento iterativo. Vengono presentati dei risultati numerici relativi al caso bidimensionale di un cilindro ellittico ed al caso tridimensionale di sferoidi prolati di diversa eccentricità. I risultati vengono discussi in relazione a soluzioni analitiche e dati sperimentali ottenuti dalla letteratura.

     

Ambient mass spectrometry: bringing MS into the “real world”

Mass spectrometry has recently undergone a second contemporary revolution with the introduction of a new group of desorption/ionization (DI) techniques known collectively as ambient mass spectrometry. Performed in an open atmosphere directly on samples in their natural environments or matrices, or by using auxiliary surfaces, ambient mass spectrometry (MS) has greatly simplified and increased the speed of MS analysis. Since its debut in 2004 there has been explosive growth in the applications and variants of ambient MS, and a very comprehensive set of techniques based on different desorption and ionization mechanisms is now available. Most types of molecules with a large range of masses and polarities can be ionized with great ease and simplicity with the outstanding combination of the speed, selectivity, and sensitivity of MS detection. This review describes and compares the basis of ionization and the concepts of the most promising ambient MS techniques known to date and illustrates, via typical analytical and bioanalytical applications, how ambient MS is helping to bring MS analysis deeper than ever into the “real world” open atmosphere environment—to wherever MS is needed.     

On the derivation and analysis of the “machine equation” in finite deformations

Received: 23 June 1998/Accepted: 15 July 1998