Assessing the health research’s social impact: a systematic review

Scientometrics - In recent year, a growing attention is dedicated to the assessment of research’s social impact. While prior research has often dealt with results of research, the last decade...     

Mechanical squeezing of an elastomeric nanochannel device: numerical simulations and ionic current characterization

Peculiar transport phenomena appear at nanoscale, since surface effects strongly affect the behaviour of fluids. Electrostatic and steric interactions, capillary forces and entropic effects play a key role in the behaviour of fluids and biomolecules. Since these effects strongly depend on the size of the nanofluidic system, a careful characterization of the fluidic environment is necessary. Moreover, the possibility to dynamically modulate the size of nanochannels is very appealing in the field of biomolecule manipulation. Recently, we have developed a lab-on-chip made of poly(dimethylsiloxane) (PDMS). This polymeric device is based on a tuneable nanochannel able to dynamically change its dimension in order to fit the application of interest. In fact, a mechanical compression applied on the top of the elastomeric device squeezes the nanochannel, reducing the channel cross section and allowing a dynamical optimization of the nanostructures. In this paper, this squeezing process is fully characterized both numerically and experimentally. This analysis provides information on the reduction of the nanochannel dimensions induced by compression as a function of the work of adhesion and of the stiffness of the materials composing the device. Moreover, calculations demonstrate the possibility to predict the change of the nanochannel size and shape induced by the compression. The possibility to dynamically tune the channel size opens up new opportunities in biomolecular sensing or sieving and in the study of new hydrodynamics effects.     

Fuzzy methodology for frequency response estimation of uncertain dynamic systems

Fuzzy frequency response: definition and analysis for uncertain dynamic systems is proposed in this paper. In terms of transfer function, the uncertain dynamic system is partitioned into several linear sub‐models and organized according to Takagi–Sugeno fuzzy representation. The main contribution of this paper is to demonstrate through the proposal of a Theorem that fuzzy frequency response is a boundary in the magnitude and phase Bode plots. Low‐ and high‐frequency analysis of fuzzy dynamic model is obtained by varying the frequency ω from zero to infinity. Copyright © 2011 John Wiley & Sons, Ltd.     

Analysis of the complex phase error introduced by the application of the Fourier transform method

Abstract

The relation between modulus and phase errors introduced by the application of the Fourier transform method to fringe pattern analysis has been established. The theoretical results obtained are proposed for the reconstructed phase error correction. Numerical verification for a one-dimensional fringe pattern, comparison of corrected and non-corrected results obtained for different basic spatial frequencies and an example of application of the proposed correction for real data are given.     

Conjugation of amino-bioactive glasses with 5-aminofluorescein as probe molecule for the development of pH sensitive stimuli-responsive biomaterials

Bioceramics, such as silica-based glasses, are widely used in bone and teeth restoration. Nowadays, the association between nanotechnology and pharmacology is one of the most promising research fields in cancer therapy. The advanced processing methods and new chemical strategies allow the incorporation of drugs within them or on their functionalized surfaces. Bioceramics can act as local drug delivery systems to treat bone and teeth diseases. The present paper reports data related to the development of a pH-stimuli responsive bioactive glass. The glass conjugation with 5-aminofluorescein (5-AF), through a pH-sensitive organic spacer, allows to produce a pH-responsive bioactive biomaterial: when it is exposed to specific pH changes, it can favour the release of 5-AF directly at the target site. 5-AF has been chosen as a simple, low cost, non toxic model to simulate doxorubicin, an anticancer drug. As doxorubicin, 5-AF contains an amino group in its structure in order to form an amide bond with the carboxylic functionalities of the glass. Raman spectroscopy and thermal analysis confirm the glass conjugation of 5-AF by means of an amide bond; the amount of 5-AF loaded was very high (≈65 and 44 wt%). The release tests at two different pH (4.2 and 7.4) show that the amount of released 5-AF is higher at acid pH with respect to physiological one. This preliminary datum evidenced that a pH-sensitive drug delivery system has been developed. The low amount of 5-AF released (<1 wt% of the total 5-AF) is due to the very low solubility of 5-AF in aqueous medium. This disadvantage, may be overcome in a dynamic environment (physiological conditions), where it is possible to obtain a drug release system ensuring an effective therapeutic dose for long times and, at the same time, avoiding the drug toxicity.     

Metallopolymers based on a polyazomethine ligand containing rigid oxadiazole and flexible tetramethyldisiloxane units

Soluble, easily processable polymer–metal complexes with improved optical and dielectric properties for optoelectronic functional materials were obtained. For this, a new polyazomethine (PAZ2) was prepared by the reaction of a siloxane dialdehyde and bis(formyl‐p‐phenoxymethyl) tetramethyldisiloxane with 2,5‐bis(p‐aminophenyl)‐1,3,4‐oxadiazole, and it was used as a ligand for Cu(II), Co(II), and Zn(II) ions on the basis of the presence of the electron‐donor nitrogen atoms from the azomethine group and oxadiazole ring. The structure of the PAZ2 was determined by spectral [Fourier transform infrared (FTIR) and ¹H‐NMR spectroscopy] techniques. The metal complexation was proven by FTIR spectroscopy, and the silicon‐to‐metal ratios in the complexes were established by energy‐dispersive X‐ray fluorescence. The new materials were characterized by gel permeation chromatography, thermogravimetric analysis, and differential scanning calorimetry. The optical properties of PAZ2 and the derived metal complexes were studied by ultraviolet–visible and fluorescence spectroscopies. PAZ2 shows fluorescence emission, and it was significantly enhanced by metal complexation. The emission was enhanced by protonation; this behavior is useful, especially for sensors. The electrical properties were investigated by dielectric spectroscopy at various frequencies and temperatures, and this emphasized the existence of dipolar relaxations. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41631.     

New approach for robust multi-objective optimization of turning parameters using probabilistic genetic algorithm

Limited by techniques, the process of remanufacturing exists masses of uncertainties which have a great impact on the remanufactured parts quality, how to achieve a higher quality of mechanical products by using limited remanufactured parts precision, has become one of the key issues of remanufacturing industry. Firstly, with a target to reduce uncertainties and improve the quality of automatic products, a method of tolerance grading allocation for remanufactured parts is proposed based on the uncertainty analysis of the remanufacturing assembly. The dimensional tolerances of the mechanical parts are divided into positive and negative two groups. We use selective assembly method to reduce assembling deviation. Then, the method is proven by mathematical formulas that the remanufactured parts variance can be expanded to two times, and the tolerances can be liberalized 40 % through tolerance grading allocation method. It is also the theoretical basis for improving the reuse radio and quantitatively describing the tolerance liberalization in this paper. Finally, feasibility research on this method is studied from the angle of cost–benefit. Furthermore, a tolerance grading allocation example of remanufactured engine piston assembly in a power corporation shows the validity and practicality of the proposed method.     

Dielectric study of side-chain liquid crystalline polyazomethine/fullerene C<Subscript>60</Subscript> nanocomposite

For side-chain liquid crystalline polyazomethine/fullerene C₆₀ nanocomposite (C₆₀ loading is 0.25 wt%), both real and imaginary components of the dielectric permittivity were investigated in wide regions of temperature and frequency. Analysis of frequency dependent permittivity allowed finding three relaxations (α, β ₁ and β ₂) in the nanocomposite. They were attributed to specific modes of molecular mobility. β-relaxations were described with the Arrhenius equation, whereas α-relaxation was described with the Vogel-Fulcher-Tammann equation. Anti-plasticization effect of the C₆₀ doping was shown to be manifested as an increase of the glass transition temperature of the nanocomposite as compared with that of the neat polymer.     

Photocuring of cycloaliphatic epoxy formulations using polyesters with multiarm star topology as additives

Multiam star polyesters were synthesized by growing poly(ε‐caprolactone) (PCL) arms from hyperbranched polyesters cores of different molecular weight and used as polymeric modifiers in UV‐curable cationic formulations based on a biscycloaliphatic epoxy resin. The effect of the multiarm stars on the curing kinetics has been investigated by real‐time FTIR. The thermal‐mechanical properties of the photocured thermosets have been studied with calorimetry and dynamomechanical and thermogravimetric analysis. Impact strength tests have been performed to assess their effect on the toughness of the cured materials. An accelerative effect of these modifiers has been observed as a consequence of the participation of the hydroxyl groups of the modifiers in the cationic curing of the epoxy resin. A modest increase in toughness accompanied by a decrease in the glass transition are observed, as a consequence of the incorporation of the modifiers into the network structure, leading to homogeneous, in situ reinforced materials. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40005.     

The use of multiarm star‐like polymers in the preparation of epoxy thermosets by UV‐cationic photopolymerization. Effect of the arms of the star in the curing process and in the final properties and morphology

New epoxy thermosets have been prepared via cationic UV‐photopolymerization introducing two different multiarm star‐like polymers. Both stars have a poly(glycidol) core but one has poly(methylmetacrylate) arms and the other poly(ε?caprolactone) ones. The characterization of the curing process has been performed by Real‐Time FTIR and photo‐DSC, observing a slight reduction in the curing rate on increasing the proportion of star. The thermosets prepared were characterized by gel content determination, DMTA and TGA, and finally the morphology observed by FE‐SEM, demonstrating the formation of nanophases in the case of the star with poly(ε?caprolactone) arms. POLYM. ENG. SCI., 54:17–23, 2014. © 2013 Society of Plastics Engineers