Unexpected high ordering of a [60]Fullerene nitroxide in the nematic phase of 4-4'-azoxyanisole

A nitroxide [60]fullerene adduct containing a pyrrolidine-1-oxyl group has been synthesized. Its orientational order in the nematic phase of the liquid crystal solvent 4,4'-azoxyanisole (PAA) has been measured from the variation of the EPR spectral parameters on passing from the isotropic to the nematic phase. Highly resolved EPR lines allow for precise evaluation of the shifts of the g , a N and a H values. Since the g and the hyperfine tensors are known, the order matrix could be obtained. This is compared with the one calculated with a theoretical model based on short range solute-solvent interactions, which predicts a considerable degree of orientation of the molecular axes, despite the almost spherical shape of the molecule. The agreement with experimental findings is quite good and it is further improved if a bent structure of the pyrrolidine ring is taken into account.     

Inclusive Science Education: Classroom Teacher and Science Educator Experiences in CLASS Workshops

Inclusion is the meaningful participation of students with disabilities in general education classrooms. The CLASS project (Creating Laboratory Access for Science Students) is a unique initiative offering training and resources to help educators provide students with a variety of physical, sensory and learning disabilities equal access in the science laboratory or field. To determine whether participants believed a 2‐week residential workshop sponsored by CLASS raised disability awareness and provided teacher training in inclusive science teaching practice, a multipoint Likert scale survey and questionnaire was completed by all participants (N= 20) in four workshops. Participants reported large gains in their preparedness to teach science to students with disabilities. Participants also reported gains in their familiarity with instructional strategies, curricula, and resources and their ability to design, select, and modify activities for students with disabilities. Finally, shifts in attitudes about teaching science to students with disabilities were noted.     

From 3-D Nonlinear Elasticity Theory to 1-D Bars with Nonconvex Energy

This paper represents a first attempt to derive one-dimensional models with non-convex strain energy starting from “genuine” three-dimensional, nonlinear, compressible, elasticity theory. Following the usual method of obtaining beam theories, we show here for a constrained kinematics appropriate for long cylinders governed by a polyconvex, objective, stored energy function, that the bar model originally proposed by Ericksen [3] is obtainable but enriched by an additional term in the strain gradient. This term, characteristic of nonsimple grade-2 materials, penalizes interfacial energies and makes single-interface two-phase solutions preferred. The resulting model has been proposed by a number of authors to describe the phenomenon of necking and cold drawing in polymeric fibers and, here, we discuss its suitability to interpret also the elastic-plastic behavior of metallic tensile bars under monotone loading.     

Thermal Stability and Molecular Ordering of Organic Semiconductor Monolayers: Effect of an Anchor Group

The thermal stability and molecular order in monolayers of two organic semiconductors, PBI‐PA and PBI‐alkyl, based on perylene derivatives with an identical molecular structure except for an anchor group for attachment to the substrate in PBI‐PA, are reported. In situ X‐ray reflectivity measurements are used to follow the stability of these monolayers in terms of order and thickness as temperature is increased. Films have thicknesses corresponding approximately to the length of one molecule; molecules stand upright on the substrate with a defined structure. PBI‐PA monolayers have a high degree of order at room temperature and a stable film exists up to 250 °C, but decomposes rapidly above 300 °C. In contrast, stable physisorbed PBI‐alkyl monolayers only exist up to 100 °C. Above the bulk melting point at 200 °C no more order exists. The results encourage using anchor groups in monolayers for various applications as it allows enhanced stability at the interface with the substrate.     

Synthesis,Characterization, and Biological Evaluation of a Dual-Action Ligand Targeting αvβ3 Integrin and VEGF Receptors

A dual-action ligand targeting both integrin α_Vβ₃ and vascular endothelial growth factor receptors (VEGFRs), was synthesized via conjugation of a cyclic peptidomimetic α_Vβ₃ Arg-Gly-Asp (RGD) ligand with a decapentapeptide. The latter was obtained from a known VEGFR antagonist by acetylation at the Lys13 side chain. Functionalization of the precursor ligands was carried out in solution and in the solid phase, affording two fragments: an alkyne VEGFR ligand and the azide integrin α_Vβ₃ ligand, which were conjugated by click chemistry. Circular dichroism studies confirmed that both the RGD and VEGFR ligand portions of the dual-action compound substantially adopt the biologically active conformation. In vitro binding assays on isolated integrin α_Vβ₃ and VEGFR-1 showed that the dual-action conjugate retains a good level of affinity for both its target receptors, although with one order of magnitude (10/20 times) decrease in potency. The dual-action ligand strongly inhibited the VEGF-induced morphogenesis in Human Umbilical Vein Endothelial Cells (HUVECs). Remarkably, its efficiency in preventing the formation of new blood vessels was similar to that of the original individual ligands, despite the worse affinity towards integrin α_Vβ₃ and VEGFR-1.     

Label-free quantification of Tacrolimus in biological samples by atomic force microscopy

In the present paper we describe an atomic force microscopy (AFM)-based method for the quantitative analysis of FK506 (Tacrolimus) in whole blood (WB) samples. Current reference methods used to quantify this immunosuppressive drug are based on mass spectrometry. In addition, an immunoenzymatic assay (ELISA) has been developed and is widely used in clinic, even though it shows a small but consistent overestimation of the actual drug concentration when compared with the mass spectrometry method. The AFM biosensor presented herein utilises the endogen drug receptor, FKBP12, to quantify Tacrolimus levels. The biosensor was first assayed to detect the free drug in solution, and subsequently used for the detection of Tacrolimus in blood samples. The sensor was suitable to generate a dose–response curve in the full range of clinical drug monitoring. A comparison with the clinically tested ELISA assay is also reported.     

Some finite extremum principles in piecewise linear elasto-plasticity

Summary The paper discusses the boundary value problem for isotropic continua with elastic-linear hardening stress-strain laws of conventional deformation theory. A pair of dual extremum theorems are proven: the first, which takes as variables stresses and plastic strains, reduces the problem to the minimization of a quadratic functional subject to convex quadratic inequalities and linear equalities; the latter, which takes as variables displacements and plastic strains, reduces the problem to the minimization of a non-quadratic functional subject to linear equalities. In absence of hardening the first principle reduces to the well-known Haar-Kármán theorem for elastic perfectly plastic bodies. Some extensions of the above principles to piecewise linear hardening bodies and the connections of the deformation theory with the flow theory of linear kinematic hardening are reported at the end of the paper.

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Sommario Si discute il problema dell'analisi elastoplastica dei mezzi isotropi dotati d'incrudimento lineare adottando le ipotesi della teoria della deformazione.Vengono dimostrati due principi di estremo duali che consentono di ricondurre la soluzione dei problemi al contorno alla minimizzazione di opportuni funzionali.Il primo di tali principii, in assenza d'incrudimento, si riduce al ben noto teorema di Haar-Karman che viene quindi generalizzato ai mezzi incrudenti.Viene discussa anche l'estensione di quanto sopra accennato al caso d'incrudimento lineare a tratti e la Nota è chiusa da alcune considerazioni in merito alla connessione fra la teoria della deformazione e la teoria incrementale dell'incrudimento cinematico.

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The results presented in this paper were obtained in the course of research sponsored by the National (Italian) Research Council (C.N.R.).     

The Kinematics of Plate Models: A Geometrical Deduction

We present a deduction of the Kirchhoff–Love and Reissner–Mindlin kinematics of a simply-connected plate by using the formal asymptotic development method applied to the compatibility conditions of Saint-Venant and the formula of Cesàro–Volterra. This formal deduction is purely geometrical because we do not use any information coming from the loading or the constitutive behavior.