cospectrality of two graphs measures the differences between the ordered spectrum of these graphs in various ways. actually,the origin of this concept came back to richard brualdi's problems that are proposed in cite{braldi}:let $g_n$ and $g'_n$ be two nonisomorphic simple graphs on $n$ vertices with spectra$$lambda_1 geq lambda_2 geq cdots geq lambda_n ;;;text{and};;; lambda'_1 geq lambda'_2 g...

Reactive extrusion of poly(L-lactide) (PLLA) was carried out in the presence of a small amount of various peroxides with relatively slow decomposition rates. The resulting crosslinked, four-armed randomly branched PLLA (v-PLLA) was characterized by size exclusion chromatography equipped with multiangle laser light scattering (SEC-MALS), and the results were interpreted according to the type of ...

The degradation of high molecular weight as-polymerized poly(L-lactide) (PLLA) is very slow; it takes more than 5.6 yr for total resorption. Moreover, the degradation products of as-polymerized PLLA bone plates, consisting of numerous stable particles of high crystallinity, are related with a subcutaneous swelling in patients 3yr postoperatively. In order to avoid these complications, polymers ...

We developed a nanofiber scaffold by blending PLLA with collagen I, suitable for bone regeneration. Among several PLLA-COLI ratios tested, cell growth was better enhanced when blends with a ratio of PLLA-COLI 4:1 were used. Here, growth as well as osteoblast differentiation of hMSC was improved when compared to PLLA nanofibers alone. Therefore, blending is a suitable tool to enhance PLLA nanofi...

Biodegradable poly(L-lactide) (PLLA)/multiwalled carbon nanotubes (MWNTs) nanocomposites were prepared via solution blending using two kinds of MWNTs, i.e., pristine multiwalled carbon nanotubes (p-MWNTs) and carboxyl-functionalized multiwalled carbon nanotubes (f-MWNTs). Various techniques were used to investigate the functionalization of MWNTs on the morphology, crystallization, and hydrolyti...

Porous titanium (pTi) can possess a low Young's modulus equal to that of human bone, depending on its porosity. However, the mechanical strength of pTi deteriorates greatly with increasing porosity. On the other hand, certain medical polymers exhibit biofunctionalities, which are not possessed intrinsically by metallic materials. Therefore, a biodegradable medical polymer, poly-L-lactic acid (P...

Morphine-loaded poly(L-lactide)-poly(ethylene glycol)-poly(L-lactide) (PLLA-PEG-PLLA) microparticles were prepared using solution enhanced dispersion by supercritical CO2 (SEDS). The effects of process variables on the morphology, particles size, drug loading (DL), encapsulation efficiency and release properties of the microparticles were investigated. All particles showed spherical or ellipsoi...

Miniemulsion homopolymerization reactions of methyl methacrylate (MMA) and styrene (STY) using poly(L-lactide) as co-stabilizer were carried out in order to prepare poly(L-lactide)/poly(methyl methacrylate) (PLLA/PMMA) and poly(L-lactide)/polystyrene (PLLA/PS) binary blend nanoparticles. The effect of PLLA concentration on methyl methacrylate (MMA) and styrene (STY) homopolymerization reactions...

In order to accelerate the crystallization of poly(L-lactic acid) (PLLA) biopolymer and enhance its crystallizability, biocompatible and environmentally friendly tungsten disulphide inorganic nanotubes (INT-WS2) were introduced into the polymer matrix. The non-isothermal cold-crystallization and subsequent melting behaviour of pure PLLA and PLLA/INT-WS2 nanocomposites were investigated in detai...

Drug-loaded electrospun PLLA membranes are not conducive to adhesion between materials and tissues due to the strong hydrophobicity of PLLA, which possibly attenuate the drugs' effect loaded on the materials. In the present work, we developed a facile method to improve the hydrophilicity of doxorubicin (DOX)-loaded electrospun PLLA fibrous membranes, which could enhance the anti-tumor effect at...