1,459 research outputs found
Phytochemical and biological characterization of dry outer scales extract from Tropea red onion (Allium cepa L. var. Tropea)–A promising inhibitor of pancreatic lipase
No full textBackground: Allium cepa L. var. Tropea is typically cultivated in Calabria (Italy) and it is certified as “Cipolla Rossa di Tropea Calabria-PGI” (Tropea red onion). The use of clinically available anti-obesity drugs such as Orlistat is being gradually dismissed due to their side-effects and this has encouraged the search for alternative inhibitors of intestinal lipases such as phytochemicals showing less side-effects. In this study we aimed to evaluate for the first time the anti-obesity potential of the hydroalcoholic extract from the dry outer scales of Tropea red onion by the assesment of its capacity to inhibit pancreatic lipase. Its possible mechanism of action was also studied with planar lipid membranes (PLMs) surrogate of intestinal membranes. Methods: Specialized metabolites in the extract were determined by GC–MS, HPLC-DAD, HPLC-UV-DAD and HPLC-HRMS analyses. Inhibition of pancreatic lipase was studied in vitro against crude lipase Type II from porcine pancreas. PLMs used in the electrophysiology measurements were made up of DOPS:DOPE:POPC. Results: The extract contained quercetin-4′-O-glucoside, quercetin and quercetin-3,4′-O-diglucoside as the most abundant phenolics. Among apolar constituents, γ-sitosterol, linoleic and stearic acids were dominant. The lipase inhibitory effect of the extract had an IC50 value equal to 0.77±0.03 mg/mL (positive control, IC50 = 0.018 mg/mL). The electrophysiological study demonstrated that the extract is able to incorporate into PLMs and to form transient channel-like events Conclusions: Taken altogether, the results allow us to suggest that the hydroalcoholic extract from the dry outer scales of Tropea red onion could prevent lipid ester hydrolysis and it has a protective effect against phospholipase as found for interfacially active compounds
A Simulator for Creating Drones Networks and Providing Users Connectivity
No full textUnmanned aerial vehicles are devices able to perform many different tasks that can help human activity in many processes. One of the most important use regards the possibility of giving wireless connectivity to user in a specific area. These new typologies of networks are called Flying Adhoc Network. Their use benefit all those situations of emergency where the traditional communications may have many issues, due to the specific event. Different types of natural disasters (such as climatological, meteorological, hydrological, geophysical) can result in many deaths and many economic damages. In these situations, drones can provide an additional or complementary access network, supporting web services and multimedia traffic, helping people involved in the rescue. Hence, it is clear that the possibility of using a simulator can result in a huge help to the research community. So, in this work, a Flying Ad-hoc Network simulator is proposed, able to simulate different scenarios with different coverage areas. In particular, emphasis is given to new coverage and human mobility models, in order to support more realistic situations. Some simulations have been led out to show how the simulator works
Evaluation of TCP versions over GEO satellite links
No full textIn this paper an attempt to evaluate the performance of different versions of TCP over satellite link has been performed. The throughput of the protocols has been graphed and considerations have been carried out. The considered protocols can be divided in two main categories: terrestrial protocols and satellite protocols. In the terrestrial category the well performing TCP Sack protocol has been illustrated together with TCP WestWood and his modified version, TCP WestWood+, while in the satellite category Satellite Communication Transport Protocol (SCPS-TP), and Satellite Transmission Protocol (STP) have been shown and compared. The considered protocols have been analyzed on well-known satellite link: GEO satellite link. In particular, a classical GEO satellite link and a single connection between two terminals have been considered
A new threshold switching scheme for a DVB-RCS+M return link in a terrestrian scenario
No full textThe new standard for DVB-RCS includes guidelines for mobile user in the market of aircraft, maritime and terrestrial. The standard suggests the possibility of using, in this scenario, a continuous carrier operation mode in the return channel beside the classical MF-TDMA mode. In this context it can be important a mechanism for switching between these two modalities in order to exploit in a better way the satellite resources. In this paper, after showing the typologies of applications considered in the simulation, a proposal of a novel switching mechanism is presented and the simulation results are reported in order to provide some guidelines to the satellite operators that want to adopt in their satellite system this hybrid mode. © 2012 IEEE
Routing optimization in dynamic networks based on a new entropy metric
No full textA key role in the modern telecommunication networks is played by routing aspects as the great number of works present in literature proves. In particular, in the mobile ad-hoc networks routing is a fundamental aspects because the mobile devices nature and their elevate dynamism. In fact, it is important to have the possibility of finding the minimum overhead for connectivity in the network and, calculate the communication potential through the analysis of different parameters. The focus of this paper is represented by the analysis of the entropy in this type of mobile networks. The entropy gives the possibility of studying and predicting the dynamics of mobile nodes. The knowledge of these aspects can help to optimise some key features of wireless mobile communications, such as nodes stability, channel failures, and routing costs. Many simulation campaigns have been carried out by taking into account the movement of the real nodes, obtaining beneficial results, which confirm the effectiveness of the proposed study
A New Metric for Routing Optimization in Mobile Networks Based on The Entropy Concept
No full textThe modern paradigm of Mobile Computing is playing a vital role in everyday life, both in terms of comfort and security. Unfortunately, mobility causes undesired phenomena for wireless communications, so several actions need to be take into account, in order to overcome the possible degradations introduced by mobility effects. OSI layer 3 approaches have been widely investigated in literature regarding the optimization of the whole network performance, while in this article we focus our attention on the analysis of the entropy trend for a mobile environment. The effects of mobility on entropy are investigated, as well as a new approach for predicting entropy evolution over time. In a mobile scenario, so in the considered context, the mobility entropy is able to optimise some key aspects of wireless communications, such as nodes stability, channel failures, and routing costs. In order to state the effectiveness of our proposal, many simulation campaigns have been carried out, taking into account the movement of the real nodes, confirming our assumptions
Allium cepa L. var. Tropea: a source of nutraceuticals with anti-obesity potential
No full textObesity represents the most prevalent nutritional disease and a major public health
problem that, according to WHO, has reached epidemic proportions worldwide. Obesity is
a factor of risk for several chronic diseases including diabetes, cardiovascular diseases and
cancer. There are several strategies to prevent or treat it, one of them is the inhibition of
gastrointestinal lipases. In the recent years, the side effects of some synthetic lipase
inhibitors indicated the need for alternative drugs with this activity, including natural
products. Plants provide a major dietary source for nutraceuticals with anti-obesity
potential and, in some cases, their plausible mechanism of action has been highilighted.
Following previous studies on plant investigation as a source of inhibitors of pancreatic
lipase, we present here the phytochemical and biological profile of a dry skin
hydroalcoholic extract of Allium cepa L. var. Tropea.
Flavonoid glycosides were the main specialized metabolites present in the extract, with
quercetin-4’-O-glucoside (43±0.002 μg/mg) and quercetin (84±0.004 μg/mg) as the two
main components and cyanidin-4-glucoside (1±0.001 μg/mg) as a minor component.
The ability to inhibit pancreatic lipase was evaluated in vitro by monitoring the hydrolysis
of p-nitrophenyl caprilate, which releases the yellow chromogen p-nitrophenol. The
sample was tested at different concentrations and showed a very good inhibitory activity
with IC50 value of 0.77 ± 0.03 mg/ml.
It has been shown that obesity can impair intestinal barrier function inducing alteration in
permeability and eventually causing inflammation. The effect of the extract on model
Planar Lipid Membranes (PLMs) made up of dioleoyl-phosphatidylserine: dioleoylphosphatidylethanolamine:
palmitoyl-oleoyl-phosphatidylcholine (27:27:18,w:w:w), a
surrogate of intestinal membranes, has also been investigated. The extract of A. cepa L.
var. Tropea was effective in forming channel-like pathways in the lipid bilayer.
Electrophysiological data demonstrated that the extract interacts and forms stable pores
in PLMs when added on the cis side of the medium facing the membranes. The effect of
different concentrations (0.01 and 0.02mg/mL) in the ranges of applied voltages from 20
to 120mV and from -40 to -120mV was studied. The conductance values seem to be
dependent on applied voltages decreasing as the voltage increases thus suggesting that
lower applied voltages promote the ionic flux.
Overall, results from this study suggest that it is worth to further investigate the
pharmacological potential of this extract from A. cepa L. var. Tropea and its main
nutraceutical constituents as safer therapeutic agents in anti-obesity therapy
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