Dimethyltyrosine, the Viagra of Opioids

Introduction Theintroductionof2′,6′dimethyl L tyrosine(Dmt)[1]attheN terminusofTyr Tic(1,2,3,4tetra hydroisoquinoline3carboxylicacid)containingδopi oidantagonists[2—8]enhancesreceptoraffinityand invitrobioactivitytoseveralordersofmagnitude[1]and itsap…     

Decision diagrams for the approximate analysis of Markov models

Decision diagrams of various types can be used to encode the exact state space and transition rate matrix of large Markov models. However, the exact solution of such models still requires to store at least one real vector with one entry per reachable state, a formidable limitation to the practical use of these encodings. Thus, we discuss automatic techniques for the approximate computation of performance measures when the Markov model can be compactly encoded but not exactly solved. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A geometric classification of inhomogeneities in continua with dislocations

Summary The paper proposes a geometric classification of inhomogeneities, in the sense of Noll, in bodies with continuous distribution of dislocations, based on the equivalence notion associated with homogeneous changes of the uniform reference.

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Sommario Il lavoro propone una classificazione geometrica delle disomogeneità, nel senso di Noll, in mezzi con distribuzioni continue di dislocazioni, partendo da una nozione di equivalenza associata con cambiamenti omogenei del riferimento uniforme.

     

Interactions in general continua with microstructure

This paper studies the behavior of the one dimensional Broadwell model of a discrete three velocity gas on a bounded domain 0 x 1 with specularly reflective boundary condition at x = 0, 1. For smooth initial data we show that the initial boundary value problem possesses a unique smooth solution which tends as t to a free state consisting of traveling waves f _1e (x – ct), f _2e (x + ct), f _3e (x) where each f _ie is 2-periodic. The convergence is in the weak* topology of an appropriate Orlicz-Banach state space. No smallness assumptions are made on the data.In memory of Ronald J. DiPerna     

Smectic liquid crystals as continua with latent microstructure

Smectic liquid crystals are quasi solids, which possess microstructure both of the material and local type (the nematic mictrostructure and the lamellae, respectively). They also exhibit phase transitions: from smectic B to smectic A, to nematic, to isotrtopic liquid (see [1], Ch. 7). Their study, though special, might show up general advantages and drawbacks of different types of mathematical models. Here, while intent on proving the property announced in the title, we set forth the groundwork for the continuum model (see, in a more specific and concrete mode [2]).

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Sommario I cristalli liquidi smettici sono quasi-solidi che possiedono una microstruttura sia di tipo materiale che locale (la microstruttura nematica e le lamelle, rispettivamente). Essi esibiscono anche transizioni di fase: smettici B a smettici A, a nematici, a liquidi isotropi. Il loro studio, sebbene speciale, potrebbe evidenziare vantaggi generali e difetti di vari tipi di modelli matematici. Qui, nel provare la proprietà annunciata nel titolo, si prepara il lavoro di base per il modello continue.

     

Crystal Memory near Discontinuous Triacylglycerol Phase Transitions: Models,Metastable Regimes,and Critical Points

It is proposed that “crystal memory”, observed in a discontinuous solid-liquid phase transition of saturated triacylglycerol (TAG) molecules, is due to the coexistence of solid TAG crystalline phases and a liquid TAG phase, in a superheated metastable regime. Such a coexistence has been detected. Solid crystals can act as heterogeneous nuclei onto which molecules can condense as the temperature is lowered. We outlined a mathematical model, with a single phase transition, that shows how the time-temperature observations can be explained, makes predictions, and relates them to recent experimental data. A modified Vogel-Fulcher-Tammann (VFT) equation is used to predict time-temperature relations for the observation of “crystal memory” and to show boundaries beyond which “crystal memory” is not observed. A plot of the lifetime of a metastable state versus temperature, using the modified VFT equation, agrees with recent time-temperature data. The model can be falsified through its predictions: the model possesses a critical point and we outline a procedure describing how it could be observed by changing the hydrocarbon chain length. We make predictions about how thermodynamic functions will change as the critical point is reached and as the system enters a crossover regime. The model predicts that the phenomenon of “crystal memory” will not be observed unless the system is cooled from a superheated metastable regime associated with a discontinuous phase transition.     

Optimization of a lateral flow immunoassay for the ultrasensitive detection of aflatoxin M1 in milk

A high sensitive immunoassay-based lateral flow device for semi-quantitatively determine aflatoxin M₁ (AFM₁) in milk was developed. Investigation and optimization of the competitor design and of the gold-labelling strategy allowed the attainment of the ultra-sensitive assessment of AFM₁ contamination at nanograms per litre level (LOD 20 ng L⁻¹, IC₅₀ 99 ng L⁻¹), as requested by European regulations. A one order of magnitude detectability enhancement in comparison to previously reported gold colloid immunochromatographic assays for this toxin was obtained.     

Influence of steric interactions and random side chain variations on the mesomorphic properties of bowlic mesogens

The effect of structural variations on the mesomorphic nature of columnar liquid crystals of general structure I is studied. X-ray crystal structure analyses of compounds la and 2a reveal the columnar organization of the macrocyclic cores in the solid state. The up and down asymmetry of the cores is resolved in an alternating sequence of up-up and down-down intermolecular contacts. Specific interactions between the R substituents are present, which influence the stacking distance between the cores in the down-down intermolecular contacts. Statistical incorporation of different side chains on the same macrocyclic core produces, when the difference in length between the alkyl chains is appropriate, random mixtures having wide mesomorphic ranges. The increase of disorder associated with the statistical side chain distribution on the core and with the structural heterogeneity of each component of the mixture have the effect of depressing mainly the crystal-mesophase transition temperature.