THE USE OF SOUND SPEED MEASUREMENTS IN THE EVALUATION OF POLYMERS MUCOADHESIVENESS

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Effect of Lactose on the thermogelation properties of Poloxamer 407.

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HIGH RESOLUTION ULTRASONIC SPECTROSCOPY IN THE ANALYSIS OF POLOXAMERS BEHAVIOUR

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Characterization of ternary phase diagrams by means of thermal and rheological analyses

Context: Mixtures made of oil, water and surfactants give rise to a wide range of structure with different characteristics and phase manifestations. Objective: Aim of this paper is to build up and understand the phase diagram of a model ternary system (Water, Polysorbate 80 and isopropyl myristate) by the use of common techniques such as thermal analysis and rheology, in comparison with visual assessment and polarized light microscopy. Methods: Different ternary systems were prepared and analyzed by means of DSC and rheology in order to highlight the state of water (free, interphasal, bound water) and the samples structural characteristics. Results: The resultant phase diagram is divided into four different zones. Bound water zone is predominant at elevated surfactant/oil ratios, while as the surfactant/oil ratio decreases, DSC reveals the presence of free water. Interphasal water prevails at intermediate water and surfactant content which corresponds with gels systems. Mechanical spectra allow to discern between cubic (true gel) and lamellar mesophases (weak gel), while flow curves allow to distinguish among microemulsions, emulsions or lamellar mesophases. Discussion: A deeper characterization of a model ternary phase diagram is possible, with respect to the simple visual inspection, by the use of thermal analysis and rheology. The state of water molecules and the viscoelastic characteristics of the system allow to obtain important structural considerations. Conclusions: In conclusion, the knowledge of the state of water and of the viscoelastic characteristics of the systems allow a deeper understanding of the structural features of the ternary phase diagra

Chi ha paura del potere? Politica e comunicazione negli studi sull’età moderna

Il saggio si propone di spiegare come la recente storiografia ha analizzato il rapporto fra potere e comunicazione nel corso dell’età moderna. Le ricerche svolte hanno avuto il merito di saldare molteplici frameworks metodologici (quelli della storia culturale, intellettuale, istituzionale, politica, ed economica), riuscendo così a ricostruire fitte reti di connessione tra diversi luoghi lontani e rilevando la presenza di un sistema globale già a partire dal XVI secolo. Tuttavia i modelli interpretativi correnti non paiono ancora sufficienti a disvelare la fabbrica dell’informazione. Quello che manca è una focalizzazione sulle forze sociali, politiche ed economiche che plasmano l’informazione e veicolano i flussi comunicativi. È quindi necessario – sottolineano gli autori – affinare gli strumenti di indagine per identificare chi costruisce le notizie e quali poteri esercitano la loro egemonia sull’infosfera.The essay aims to explain how recent historiography has analyzed the relationship between power and communication in the early modern age. The research carried out had the merit of welding multiple methodological frameworks (those of cultural, intellectual, institutional, political, and economic history), thus succeeding in reconstructing dense networks of connection among different distant places and detecting the presence of a global system since the beginning of the 16th century. However, current interpretative models still do not seem sufficient to unveil the information factory. What is missing is a deeper focus on the social, political, and economic forces that shape information and convey communication flows. It is therefore necessary – the authors argue – to refine the investigation tools to identify who builds the news and which powers exercise their hegemony over the infospher

Chi ha paura del potere? Politica e comunicazione negli studi sull'età moderna

This essay aims to explain how recent historiography has analysed the relationship between power and communication in the early modern age. The research that was carried out had the merit of fusing together multiple methodological frameworks (those of cultural, intellectual, institutional, political, and economic history), thus succeeding in reconstructing dense networks of linkage among different, distant places and finding the presence of a global system since the beginning of the 16th century. However, current interpretative models do not yet seem sufficient to unveil the information factory. What is missing is a deeper focus on the social, political, and economic forces that shape information and convey communication flows. It is therefore necessary – the authors argue – to refine the investigation tools to identify who builds the news and which powers exercise their hegemony over the infosphere

Assessment of Alexithymia : Pychometric Properties of the Psychological Treatment Inventory-Alexithymia Scale (PTI-AS)

The aim of this study is to investigate the psychometric properties of a new measure of alexithymia, the Psychological Treatment Inventory-Alexithymia Scale (PTI-AS)

Spray-drying as a method for microparticulate controlled release systems preparation: advantages and limits. I. Water soluble drugs

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Mechanical characterization of pharmaceutical solids: a comparison between rheological tests performed under static and dynamic porosity conditions.

The aim of this work was to verify how and to what extent rheological tests, carried out under dynamic (Heckel) and static (creep, stress/strain) porosity conditions, may serve as a valuable complement to the classic Heckel tests in the characterization of viscoelastic and densification properties of solid materials for pharmaceutical use. Six different modified (pregelatinized) starches were compressed in a rotary tablet machine equipped to measure force and punch displacement. Tablets were obtained using flat-faced 6 mm diameter punches at different compression pressures. Compression cycles performed at the maximal pressure of 200 MPa were used to build the Heckel plots. Ejected tablets at the 10%, 20%, 30%, and 40% porosity levels were used for the stress/strain and creep tests. Parameters obtained with both types of tests were consistent with each other. In particular, among the six starches, lower viscosity values corresponded to lower PY values, and lower elastic modulus values corresponded to lower elastic recovery of the tablet. Mechanical properties of materials can be better characterized if viscoelastic tests performed under dynamic porosity conditions (Heckel analysis) are supported by classical viscoelastic tests carried out under conditions of static porosity

Rheological, adhesive and release characterisation of semisolid Carbopol/Tetraglycol systems

Gels dosage forms are successfully used as drug delivery systems considering their ability to control drug release and to protect medicaments from an hostile environment. This study deals with the gelation properties of Carbopol 971 e 974 polymeric systems in tetraglycol, a water-miscible cosolvent. In this paper, the attention was noted of the thickening properties of the different Carbopol in tetraglycol solvent at increasing temperatures, in order to obtain gels avoiding neutralisation and, at the same time, to make possible the dissolution in these gels of insoluble or poorly soluble water drugs. Samples were prepared by simply dispersing different Carbopols amount (0.5-4%) were added to tetraglycol and different systems were prepared at room temperature and by heating at 70 °C. All these systems were then characterised rheologically. Frequency sweep, creep-recovery, temperature sweep and time sweep analyses outlined that Carbopol 971 and 974 in tetraglycol gave rise after heating to gels with satisfactory rheological behaviour: the elastic modulus was greater than the viscous one and a remarkable elastic character was found to be present. Systems obtained by heating procedure were examined also from a mechanical point of view using a texture profile analysis. Besides, being Carbopols well known mucoadhesive polymers, gels adhesive properties were also studied using the ex vivo method. Texture and adhesion characterisation confirmed rheological results pointing out a certain greater elasticity and adhesiveness of Carbopol 974 systems. Then, the possible cutaneous irritation was also tested using the in vivo method (Draize test). No signs of cutaneous irritation were obtained for all the samples that were analysed. After rheological and mucoadhesive properties were set, paracetamol as a model drug was inserted in the composition of the gels and the release characteristics were defined. Dissolution tests pointed out the greater release control properties of tetraglycol/Carbopol 971 samples. These studies showed tetraglycol/Carbopol systems as a first-rate alternative to traditional water gels when low water-soluble drugs have to be added