Turbulent Drag Reduction by Biopolymers in Large Scale Pipes

In this work, we describe drag reduction experiments performed in a large diameter pipe (i.d. 100mm) using a semirigid biopolymer Xanthan Gum (XG). The objective is to build a self-consistent data base which can be used for validation purposes. To aim this, we ran a series of tests measuring friction factor at different XG concentrations (0.01, 0.05, 0.075, 0.1, and 0.2% w/w XG) and at different values of Reynolds number (from 758 to 297,000). For each concentration, we obtain also the rheological characterization of the test fluid. Our data is in excellent agreement with data collected in a different industrial scale test rig. The data is used to validate design equations available from the literature. Our data compare well with data gathered in small scale rigs and scaled up using empirically based design equations and with data collected for pipes having other than round cross section. Our data confirm the validity of a design equation inferred from direct nu- merical simulation (DNS) which was recently proposed to predict the friction factor. We show that scaling procedures based on this last equation can assist the design of piping systems in which polymer drag reduction can be exploited in a cost effective way

An engineering insight into the relationship of selective cytoskeletal impairment and biomechanics of HeLa cells

It is widely accepted that the pathological state of cells is characterized by a modification of mechanical properties, affecting cellular shape and viscoelasticity as well as adhesion behaviour and motility. Thus, assessing these parameters could represent an interesting tool to monitor disease development and progression, but also the effects of drug treatments. Since biomechanical properties of cells are strongly related to cytoskeletal architecture, in this work we extensively studied the effects of selective impairments of actin microfilaments and microtubules on HeLa cells through force-deformation curves and stress relaxation tests with atomic force microscopy. Confocal microscopy was also used to display the effects of the used drugs on the cytoskeletal structure. In synergy with the aforementioned methods, stress relaxation data were used to assess the storage and loss moduli, as a complementary way to describe the influence of cytoskeletal components on cellular viscoelasticity. Our results indicate that F-actin and microtubules play a complementary role in the cell stiffness and viscoelasticity, and both are fundamental for the adhesion properties. Our data support also the application of biomechanics as a tool to study diseases and their treatments

Moringa oleifera Leaf Powder as Functional Additive in Cookies to Protect SH-SY5Y Cells

The aim of this work is the evaluation of the addition of Moringa leaf powder (MLP) in cookies in terms of antioxidant properties, dough processability and sensorial properties of the cookies. The total content of biophenols and flavonoids in MLP was detected and the identification of the bioactive molecules was performed by HPLC-ESI-TOF-MS measurements, before and after oven treatment at 180 ◦C for 20 min. After a preliminary evaluation of the MLP water soluble fraction (MLPsf) cytotoxicity, its protective effect against an oxidative injury induced in the SH-SY5Y cells was assessed. Data evidence that the bioactive molecules present in MLPsf are effective in preventing ROS production and in protecting neuronal cells against oxidative stress. Prototypes of cookies containing MLP in different concentrations were then produced and evaluated by a consumer panel. Selected doughs containing MLP were analysed to determine the total content of biophenols in the cookies after baking and their enrichment in terms of valuable chemical elements. The influence of MLP on the viscoelastic behaviour and morphology of the doughs was also assessed. Finally, the potential role in counteracting the insurgence of not treatable neurodegenerative pathologies of two main MLP components, glucomoringin and kaempferol derivatives, present also after the thermal treatment, was discussed

Potential applications of nanocellulose-containing materials in the biomedical field

Because of its high biocompatibility, bio-degradability, low-cost and easy availability, cellulose finds application in disparate areas of research. Here we focus our attention on the most recent and attractive potential applications of cellulose in the biomedical field. We first describe the chemical/structural composition of cellulose fibers, the cellulose sources/features and cellulose chemical modifications employed to improve its properties. We then move to the description of cellulose potential applications in biomedicine. In this field, cellulose is most considered in recent research in the form of nano-sized particle, i.e., nanofiber cellulose (NFC) or cellulose nanocrystal (CNC). NFC is obtained from cellulose via chemical and mechanical methods. CNC can be obtained from macroscopic or microscopic forms of cellulose following strong acid hydrolysis. NFC and CNC are used for several reasons including the mechanical properties, the extended surface area and the low toxicity. Here we present some potential applications of nano-sized cellulose in the fields of wound healing, bone-cartilage regeneration, dental application and different human diseases including cancer. To witness the close proximity of nano-sized cellulose to the practical biomedical use, examples of recent clinical trials are also reported. Altogether, the described examples strongly support the enormous application potential of nano-sized cellulose in the biomedical field

Rheology of aqueous dispersions of Laponite and TEMPO-oxidized nanofibrillated cellulose

The viscoelastic and flow properties of aqueous Laponite/TEMPO-oxidized nanofibrillated cellulose (TEMPO-NFC) systems are investigated with the aim to study the effect of content and proportion of both components on the properties. Both Laponite and TEMPO-NFC aqueous dispersions can find numerous applications in different fields (from industrial to biomedical one) due to their structural and rheological properties. The most important effects of blending are observed at low Laponite fractions, also with qualitative changes in the shape of the flow curves and mechanical spectra. Positive synergistic effects are ascribed to the interpenetration and electrostatic interactions between TEMPO-NFC fibrils and Laponite nanodisks. These mechanisms are more effective in Laponite-poor blends when a minority of clay nanoparticles and its aggregated forms are distributed within the nanocellulose matrix, acting as bridging agents between polymer nanofibrils. The synergistic effects are compared to those observed for Laponite blends with a nonionic biopolymer, scleroglucan

Caratterizzazione reologica e modellazione di colate detritiche nel bacino idrografico del Fella

Nella giornata del 29 agosto 2003 il settore nord-orientale della regione Friuli Venezia Giulia \ue8 stato colpito da violente precipitazioni (circa 300 mm in sei ore), che hanno dato origine a numerose colate detritiche, anche di grande entit\ue0. Una di queste, avente un volume totale stimato pari a 100000 m3, ha interessato il versante in destra idrografica del fiume Fella, nell\u2019alto bacino del Tagliamento (Rio Cucco), ed \ue8 stata oggetto di una simulazione numerica (back analysis) svolta utilizzando il codice commerciale di calcolo Flo-2D che ha permesso di individuare i valori dei parametri reologici che meglio descrivono l\u2019evento. Il presente lavoro riporta i risultati di un\u2019indagine sperimentale svolta su sospensioni acquose della frazione fine (passante a 63 micron) ottenuta per setacciatura da campioni prelevati nell\u2019area interessata dal fenomeno. Lo studio ha riguardato gli effetti del contenuto di fase solida sulle propriet\ue0 shear- e tempo-dipendenti, con particolare attenzione ai parametri reologici (limite di scorrimento e viscosit\ue0 plastica) che servono alla simulazione numerica del debris flow, al fine di confrontare tra loro i risultati delle prove di laboratorio e della back analysis