Search results for "polymers"

Injectable in situ forming microgels of hyaluronic acid-g-polylactic acid for methylprednisolone release

2013

Abstract A hydrophobic derivative of hyaluronic acid (HA), obtained by grafting polylactic acid (PLA) to the polysaccharide, has been exploited to produce injectable in situ forming microgels. First of all, self assembling properties of HA-g-PLA copolymer have been evaluated by determining the critical aggregation concentration (CAC) value, then this copolymer has been dissolved in a mixture water/NMP 5:2 v/v with a concentration greater than CAC. When solutions at 1% or 2% w/v were injected into Dulbecco phosphate buffer solution (DPBS) pH 7.4, microgels promptly are formed. Their stability in DPBS pH 7.4 in the absence or in the presence of hyaluronidase and cell compatibility have been e…

Polymer-based systems for controlled release and targeting of drugs

2019

The current need to find new advanced approaches to carry biologically active substances (conventional organic drugs, peptides, proteins (such as antibodies), and nucleic acid-based drugs (NABDs such as siRNA and miRNA)) in the body fluids, to realize targeted therapies and even personalized ones, goes hand in hand with research on the performance of new materials to better realize appropriate drug vectors [...]

Polymer therapeutics—polymers as drugs, drug and protein conjugates and gene delivery systems: Past, present and future opportunities

2006

As the 21st century begins we are witnessing a paradigm shift in medical practice. Whereas the use of polymers in biomedical materials applications, for example as prostheses, medical devices, cont...

Ductility of Reinforced Concrete Members Externally Wrapped with Fiber-Reinforced Polymer Sheets

2007

The effectiveness of external wrapping with fiber-reinforced polymer for enhancing the curvature ductility of lightly reinforced concrete members is investigated. Referring to members with circular transverse cross sections, the performances in terms of both strength and ductility capacities are analyzed, and the predictive reliability of two different recent constitutive models, available in the literature and able to take into account the softening behavior of confined concrete, is checked. A parameter characterizing the effectiveness of the confining wrapping is proposed, and characteristic values are suggested. Moreover, referring to ductility increases due to confinement effects, a com…

Hybrid biocomposites based on polylactic acid and natural fillers from Chamaerops humilis dwarf palm and Posidonia oceanica leaves

2022

AbstractPlatelet-like and fibrous lignocellulosic fillers were achieved from the leaves of Chamaerops humilis (CHL) and Posidonia oceanica (POL) and used as a hybrid reinforcement for a polylactic acid (PLA) matrix at three different loading levels (from 5 to 20%). The materials were fully characterized from a morphological, physicochemical, mechanical, and dynamic-thermomechanical point of view. When compared to their counterpart containing either CHL or POL only, the resulting hybrid biocomposites showed the highest mechanical properties, with strengthening and stiffening effects respectively up to 120% and 50% higher than those expected from the linear combination of the two, and higher …

Electrospinning of α,β-poly(N-2-hydroxyethyl)-dl-aspartamide-graft-polylactic acid to produce a fibrillar scaffold

2010

Abstract α,β-Poly( N -2-hydroxyethyl)- dl -aspartamide grafted with polylactic acid (PHEA- g -PLA) is a biocompatible and biodegradable amphiphilic copolymer that has been already employed to prepare a drug delivery system. In this study we have prepared for the first time a fibrillar scaffold from PHEA- g -PLA by the electrospinning of a solution of this copolymer in a mixture of N , N -dimethyl formamide (DMF) and acetone (80:20 vol/vol). The average diameter and the morphology of electrospun fibers were detected by scanning electron microscopy. Chemical degradation studies in phosphate buffer solution pH 7.4 have been performed until 15 days in order to obtain a preliminary information a…

Asphalt mixtures improved with plastic additives: mix design and case study in an airport

La crescente domanda di prestazioni e le esigenze di salvaguardia dell’ecosistema spingono a sviluppare nuove tecnologie di lavorazione, a sperimentare l’impiego di nuovi materiali, a migliorare i metodi di progetto delle miscele. Il criterio seguito è quello di un impiego più razionale delle risorse e dell’utilizzo di tecniche a basso impatto ambientale. Per ragioni tecniche ed economiche stiamo assistendo al fenomeno di espansione nel mercato degli additivi, impiegati nella produzione di miscele bituminose per migliorarne le prestazioni e ridurre i costi. In generale, però riuscire a soddisfare tutti gli obiettivi con un unico prodotto è difficile, perché l’alta qualità richiede costi più…

The role of aspect ration in the mechanical properties of lignocellulosic ecocomposites obtained from MaterBi(R)

2011

Performance of MaterBi(R) based ecocomposites

2011

On John Bates Clark's “Naive Productivity Ethics”: A Note

2023

Abstract This article explores in detail the reactions among American economists to John Bates Clark's famously controversial claim that the marginal productivity theory of factor pricing and distribution is necessarily just. The general debate around Clark's “naïve productivity ethics,” as George Stigler sharply called it, transcended the then existing distinctions within the discipline and involved figures of virtually all theoretical and ideological persuasions—from prolabor progressives such as Richard T. Ely to staunch conservatives such as Thomas Nixon Carver. Our reconstruction reveals that, contrary to several standard historical accounts, for American early twentieth-century margin…