novel tri and tetrafunctional cholic acid based initiators for the synthesis of star shaped poly l lactide s

AbstractIn this investigation, two novel multifunctional initiators for ring-opening polymerization were synthesized in three steps starting from cholic acid. Thus, cholic acid (1a) and its methyl ester (1b) were quantitatively transformed, via solvent-free reaction with succinic anhydride, to the corresponding 3, 7, 12-tri-hemisuccinate derivatives (3a-b). The polyacidic compounds (3a-b) were treated with thionyl chloride affording the corresponding acyl chlorides 4a-b which, in turn, were reacted with ethylene glycol to give the derivatives 2a-b having three and four primary alcohol end groups. These compounds, fully characterized by 1H, 13C NMR and mass spectrometry, have been assessed as initiators in the ring-opening polymerization of L-lactide using stannous octanoate as catalyst. The resulting three- and four-armed star-shaped poly(L-lactide)s, which were characterized by 1H NMR, SEC, DSC and TGA analysis, were amorphous, and their glass transition temperatures ranged from 13.7 to 36.5 °C. Addition..

Association of kidney disease measures with risk of renal function worsening in patients with type 1 diabetes

Background: Albuminuria has been classically considered a marker of kidney damage progression in diabetic patients and it is routinely assessed to monitor kidney function. However, the role of a mild GFR reduction on the development of stage 653 CKD has been less explored in type 1 diabetes mellitus (T1DM) patients. Aim of the present study was to evaluate the prognostic role of kidney disease measures, namely albuminuria and reduced GFR, on the development of stage 653 CKD in a large cohort of patients affected by T1DM. Methods: A total of 4284 patients affected by T1DM followed-up at 76 diabetes centers participating to the Italian Association of Clinical Diabetologists (Associazione Medici Diabetologi, AMD) initiative constitutes the study population. Urinary albumin excretion (ACR) and estimated GFR (eGFR) were retrieved and analyzed. The incidence of stage 653 CKD (eGFR < 60 mL/min/1.73 m2) or eGFR reduction > 30% from baseline was evaluated. Results: The mean estimated GFR was 98 \ub1 17 mL/min/1.73m2 and the proportion of patients with albuminuria was 15.3% (n = 654) at baseline. About 8% (n = 337) of patients developed one of the two renal endpoints during the 4-year follow-up period. Age, albuminuria (micro or macro) and baseline eGFR < 90 ml/min/m2 were independent risk factors for stage 653 CKD and renal function worsening. When compared to patients with eGFR > 90 ml/min/1.73m2 and normoalbuminuria, those with albuminuria at baseline had a 1.69 greater risk of reaching stage 3 CKD, while patients with mild eGFR reduction (i.e. eGFR between 90 and 60 mL/min/1.73 m2) show a 3.81 greater risk that rose to 8.24 for those patients with albuminuria and mild eGFR reduction at baseline. Conclusions: Albuminuria and eGFR reduction represent independent risk factors for incident stage 653 CKD in T1DM patients. The simultaneous occurrence of reduced eGFR and albuminuria have a synergistic effect on renal function worsening

Composizione sigillante per per l’isolamento di dispositivi sensibili alla permeazione di umidità dall’ambiente esterno

The present invention relates to a sealant composition for the isolation of devices that are sensitive to permeation of moisture from the external environment. It is well known that the insulating structures for moisture-sensitive devices are made with the aid of sealants compositions having a low rate of water vapor transmission

Plastic debris in the Mediterranean Sea: Types, occurrence and distribution along Adriatic shorelines

Small plastic debris in sediments from five beaches were investigated to evaluate their occurrence and abundance in the Northern Adriatic coast for the first time. Plastic debris extracted from sediments were counted, weighted and identified by Fourier-transform infrared spectroscopy (FT-IR). A total of 1345 items of debris (13.491 g) were recorded, with a mean density of 12.1 items kg1 d.w. and 0.12 g kg1 d.w. Fragments were the most frequent type of small plastics debris detected. In terms of abundance, microplastics (<5 mm) accounted for 61% of debris, showing their wide distribution on Adriatic coasts, even far-away from densely populated areas. The majority of the polymers found were polyolefins: there were greater quantities of polyethylene and polypropylene compared to other types of plastic. Primary microplastics accounted for only 5.6% of the total plastic debris. There were greater quantities of microplastics at sites subjected to stronger riverine runoff. The results will provide useful background information for further investigations to understand the sink and sources of this emergent and priority contaminan

Interpenetrated polymer network formed by UV curable modified epoxyacrylates using dual curing polymerization

The materials and methods used for the preparation of interpenetrated polymer network (IPN) by UV curing processes are reported. In particular, recent developments on the formation and characterization of some sequential IPN based on mixtures of commercially available diglycidyl ether of bisphenol-A (DGEBA) epoxy resins and UV curable epoxy-dimethacrylate resins are discussed. Finally, the photopolymerization kinetic behavior and thermal properties of some UV curable mixtures based on the modified epoxydimethacrylate resins for the preparation and characterization of a grafted sequential IPN are described

Diffusion coefficient and activation energy of Irganox 1010 in poly(propylene-co-ethylene) copolymers

The diffusion of a thermal stabiliser, Irganox 1010, has been studied both in a commercially available polypropylene homopolymer (HomoQ) and in a poly(propylene-co-ethylene) copolymer (RacoS). The diffusion experiments were carried out by using the Roe method formed by a stack of several polymer films having 60-70 μm as thickness under nitrogen atmosphere. The concentration profile of stabiliser in every film has been monitored by the absorbance at 282 nm in UV spectra recorded for every film forming the stack assembly. Under our experimental conditions, the diffusion of Irganox 1010 in each film stack for both polymer materials can be correctly interpreted by using the Fick's second law. The best fit of the experimental data with this equation allows calculation of the diffusion coefficients, D, for these polymer materials at 40, 70 and 80°C. By applying an Arrhenius equation to the calculated D coefficients, an estimation of activation energies of the diffusion process has been also achieved

Effect of the structure of in reactor poly(propylene-co-ethylene) blends on the diffusion coefficient and activation energy of a conventional antioxidant

The diffusion of a thermal stabilizer, i.e., Irganox 1010, has been studied in three different reactor poly(propylene-co-ethylene) blends, namely HecoQ, ExpSS, and Super Soft. The diffusion experiments were carried out by using Roe's method based on a stack of several polymer films where each of them had 60-70 μm thickness. The concentration profile of the stabilizer in every film has been monitored by the absorbance at 282 nm of the recorded UV spectra. Under our experimental conditions, the diffusion of Irganox 1010 for all polymer materials can be correctly interpreted by using Fick's second law resolved under certain boundary conditions. Best-fitting the experimental data with the equation model also allows calculation of the diffusion coefficient, D, for these polymer materials at 40, 70 and 80 °C. By applying an Arrhenius-type equation to the calculated D coefficients, an estimation of activation energies of the diffusion process has been achieved. An interpretation, in terms of free volume theory, has been applied to explain the observed variation of D which depends mostly on the amount of amorphous phase of the blends

Immobilization of calix[4]arene-based glycoclusters on TiO2 nanoparticles via click Cu(i)-catalyzed azide\u2013alkyne coupling

We present the first type of tetraazide-functionalized calix[4]arene TiO2 nanoparticles and their coupling to propargyl glycosides under Cu(I)-catalysis (click reaction), resulting in the immobilization of calix[4]arene-based glycoclusters on the TiO2 surface

Polymerization Kinetics and Characterization of Dual Cured Polyurethane-Acrylate Nanocomposites for Laminates

Four different types of montmorillonites have been dispersed by sonication at 50&amp;DEG; C into a propoxylated aromatic epoxy diacrylate oligomer to achieve interlayered or exfoliated nanocomposites. A thermally-induced cross-linking reaction, forming a polyurethane network in the presence of 7 wt.-% of a montmorillonite, has been promoted by addition of an allophanate modified polyisocyanurate based on hexamethylene diisocyanate. The kinetic behavior of the network formation has been studied at 25, 40 and 60&amp;DEG; C by following the disappearance of the isocyanate vibrational band found at 2 270 cm(-1). A tight crosslinked polyurethane acrylate network has been achieved by a subsequent dual UV curing promoted by a photoinitiator mixture (0.6 wt,-%) added to the reactive mixture because of further reactions occur to the acrylate double bonds. The photopolymerization kinetic has been investigated on the different thermally treated polyurethane nanocomposite networks by Real Time FTIR spectroscopy monitoring the changes of the IR band at 810 cm(-1) assigned to the acrylate double bond vibrations. The influence of the different montmorillonite clays on the final nanocomposite morphology has been investigated by using XRD and SEM. Finally, the use of these mixtures as internal layer between two modified surface PET films has been also studied for the laminate production. The based-PET laminate films have been characterized by determining the bending resistance and optical properties as a function of different nanofiller

Rheological, thermal and spectroscopical properties of the macromolecular complex between sodium hyaluronate and cisplatin for anticancer chemotherapy

Hyaluronic acid and its sodium salt (sodium hyaluronate; hyaluronan; NaHA) are widely used for drug delivery. Here, a thin film of high molecular weight NaHA with the anticancer agent cisplatin (cisPt) was prepared to deliver the drug loco-regionally on the pleura after tumor resection. For preparing films, NaHA, cisPt, and excipients were dissolved in water; the resulting viscous film-forming mixture (FFM) was cast into wet films and dried. It was discovered that a cisPt/NaHA complexation in films was responsible for the observed higher drug efficacy from films. Here, we investigated the rheological, thermal and spectroscopical properties of the cisPt/NaHA complex. The size exclusion chromatography (SEC) showed a unimodal molecular weight distribution of NaHA in aqueous solution. The viscosity of FFM increased with increasing cisPt concentration, indicating cross-linking due to cisPt/NaHA complexation. In DSC analysis, the water evaporation temperature of both FFM and film decreased due to cisPt/NaHA complexation, suggesting that the complexation with Pt2+ displaced water molecules originally bound to NaHA. FTIR-ATR spectral changes in cisPt-loaded vs. placebo films suggested that complexation involved the carboxylate groups of the polysaccharide. Finally, energy dispersive spectroscopy coupled with SEM demonstrated that the cisPt/NaHA complex in films appeared to be a network of aggregates