Stoney equation limits for samples deformed as a cylindrical surface

This paper proposes a three-dimensional system for modelling stress in thin films deposited on thick substrates deformed as a small cylindrical surface by means of the minimization of the deformation energy. The results show the validity limits of the well-established Stoney equation and indicate the necessity of a correction term for substrates with Poisson ratio (ν_s) in the range of 0.25 < ν_s ≤ 0.4.     

PEG-PLGA electrospun nanofibrous membranes loaded with Au@Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> nanoparticles for drug delivery applications

A PEGylated-PLGA random nanofibrous membrane loaded with gold and iron oxide nanoparticles and with silibinin was prepared by electrospinning deposition. The nanofibrous membrane can be remotely controlled and activated by a laser light or magnetic field to release biological agents on demand. The nanosystems were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and thermogravimetric analyses. The drug loading efficiency and drug content percentages were determined by UV-vis optical absorption spectroscopy. The nanofibrous membrane irradiated by a relatively low-intensity laser or stimulated by a magnetic field showed sustained silibinin release for at least 60 h, without the burst effect. The proposed low-cost electrospinning procedure is capable of assembling, via a one-step procedure, a stimuli-responsive drug-loaded nanosystem with metallic nanoparticles to be externally activated for controlled drug delivery.     

Analytical investigation of the SAFE diagram for bladed wheels,numerical and experimental validation

Compressor and turbine bladed wheels interact with the fluid distributed by the stator vanes. They are subject to vibration and fatigue loading, especially when resonance conditions are excited. Avoiding resonance is fundamental when designing bladed wheels. The Campbell diagram approach is too conservative since bladed wheels show many close frequency natural modes, thus it is almost impossible to avoid frequency matching. Singh?s Advanced Frequency Evaluation (SAFE) diagram, or interference diagram, also introduces shape matching in addition to the frequency, for resonance prediction, therefore many frequency matching cases can be identified as non-critical and thus tolerated. The present paper explains and demonstrates the SAFE diagram by introducing an analytical expression to identify bladed wheel resonance conditions. The mode shape matching with a harmonic component is investigated by means of specific examples. Symmetry properties of the matching distribution of harmonic indices and mode shapes are also introduced and demonstrated. Finally, a bladed wheel analysis is used for validation, both in FE simulations and experiments.     

Polyethersulfone‐epoxy terminated materials as thermosetting resins for microelectronic devices

A totally aromatic polyether/sulfone resin (PES‐E) was synthesized and tested as an insulating glue in the construction of a Chip‐on‐Chip (CoC) device. PES‐E, essentially constituted of open‐chain macromolecules of low molecular mass (M _n of about 3000 Da) with hydroxy and/or epoxy end‐groups, has a glass transition temperature of about 150 °C and is subject to crosslinking at temperatures higher than 320 °C. A CoC device was assembled using a five‐step process by interposing a layer of PES‐E between two chips. After curing, SEM cross section images showed a homogeneous crosslinked resin layer well stuck (flick and shear tests) to both chips. The chemical structure of the chains and the hydroxy/epoxy end‐groups ratio were optimized to obtain a crosslinked material with good adhesion and sufficient flexibility to avoid cracking during assembly and use. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5682–5689, 2009     

Amorphous silicon-carbon films prepared by reactive evaporation

Summary An ion-beam-assisted deposition (IBAD) technique, based on reactive evaporation using hydrogen/ methane gas mixture, has been used for the preparation ofa-Si_1−x C _x : H films. Measurements are reported on the composition, optical gap, infra-red vibrational absorption bands and on the electrical dark-conductivity temperature dependence to verify the reliability of this deposition method. On increasing the compositional parameterx up to 0.35, the IR results show an increasing hydrogenation and the presence of Si-CH₃ units in addition to the ones with the carbon fully coordinated with the silicon, while the optical-gap and the dark-conductivity activation energies reached the values of 2.44 eV and 0.77 eV, respectively. The authors of this paper have agreed to not receive the proofs for correction     

Comments on recent developments of asymptotics

Summary Technical aspects of asymptotic procedures are correlated with recent literature on asymptotics.

---

Sommario Aspetti tecnici dei procedimenti asintotici sono posti in relazione con recenti pubblicazioni di asintotica.

---

---

Paper presented at the 8th National Congress of AIMETA Turin, September 29–October 3, 1986 (invited lecture).     

Asymmetric aziridination of cyclic enones using chiral diamine catalysts and its application to the total synthesis of (-)-agelastatin A

The asymmetric aziridination of cyclic enones with N-tosyloxycarbamates, using N-neopentyl 1,2-diphenylethylenediamine as a catalyst, and its application to the formal total synthesis of (-)-agelastatin A, using a one-pot silylation-selenylation procedure and the regioselective aziridine-opening by an azide anion as key steps, are described.