35 research outputs found
Infrastructure Vulnerability Index of drinking water systems to terrorist attacks
Drinking water supply systems are vulnerable targets for which counter-terrorism measures have been raised worldwide. The threat of terrorist attacks to these systems has led to the need for the international scientific community to deal with the vulnerability assessment related to such events. In this context, this paper proposes an Infrastructure Vulnerability Index for drinking water distribution system with the aim of providing managers with a tool to assess system vulnerability to possible terrorist acts and to support the investments choice aimed at increasing security. This index is obtained using a set of indicators with reference to the structural parts of the system and considers both intentional contamination and physical damage. The index uses a hierarchic structure and decomposes the system into components and uses the Analytic Hierarchy Process to compute the weights. An application of the index was carried out for three water schemes of the Province of Crotone (Southern Italy) and the results obtained allowed to highlight the characteristics of the index and its usefulness
Sustainable Water Management Index,SWaM_Index
The present paper describes the Sustainable Water Management Index, SWaM_Index, useful for managers to measure the sustainability of water management and to assess the effects of the policies undertaken in the direction of sustainability. The structure of the proposed index has been derived from European legal framework of the water resources sector, and the index is obtained from elementary indicators of environmental, economic, social and institutional nature, subsequently aggregated in sub-themes, themes and pillars. The index is well applicable on a national, regional but also local scale and the sustainable management of water resources is assessed considering natural systems, artificial systems and socio-economic and institutional aspects
A methodological proposal for the evaluation of potable water use risk
Water shortages are due to a number of factors such as pollution of sources, decrease of water availability, climate change, wrong use of water resources and the inaccurate management of water systems, including the physiological dysfunctions of waterwork facilities. In order to improve the planning of emergency management, forecasting and prevention of this type of risk, it is helpful to address the study of the risk of potable water use. Through the analysis of water systems in all its components, key factors have been identified that influence the incorrect operation of systems and it was possible to define the risk for potable water use in order to formulate an initial proposal for an estimation method
Shifts in chain-melting transition temperature of liposomal membranes by polymer-grafted lipids
AbstractThe chain-melting transition temperature of dipalmitoyl phosphatidylcholine (DPPC) bilayer membranes containing poly(ethylene glycol)-grafted dipalmitoyl phosphatidylethanolamine (PEG-DPPE) was determined by optical turbidity measurements. The dependence on content, Xp, of PEG-DPPE lipid was studied for different polar headgroup sizes, np, of the polymer lipid, throughout the lamellar phase of the mixtures with DPPC. Mean-field theory for the polymer brush regime predicts that the downward shift in transition temperature should vary with polymer size and content as npXp5/3 (∼npXp11/6 for scaling theory). Any shift induced by the charge on PEG-lipids is independent of polymer size. These predictions are reasonably borne out for the longer polymer lipids (PEG molecular masses 750, 2000 and 5000 Da). Transition temperature shifts in the lamellar phase, before the onset of micellisation, are in the region of −1 to −2 °C (±0.1–0.2 °C) in reasonable accord with theoretical estimates of the lateral pressure exerted by the polymer brush. Shifts of this size are significant to the design of liposomes for controlled release of contents by mild hyperthermia
Erratum to "Shifts in chain-melting transition temperature of liposomal membranes by polymer-grafted lipids" [Biochim. Biophys. Acta 1614 (2003) 165-170]
Interaction of human serum albumin with membranes containing polymer-grafted lipids: spin-label ESR studies in the mushroom and brush regimes
The adsorption of human serum albumin (HSA) to dipalmitoyl phosphatidylcholine (DPPC) bilayer membranes containing poly(ethylene glycol)-grafted dipalmitoyl phosphatidylethanolamine (PEG-DPPE) was studied as a function of content and headgroup size of the polymer lipid. In the absence of protein, conversion from the low-density mushroom regime to the high-density brush regime of polymer-lipid content is detected by the change in ESR outer hyperfine splitting, 2A(max), of chain spin-labelled phosphatidylcholine in gel-phase membranes. The values of 2A,; remain constant in the mushroom regime, but decrease on entering the brush regime. Conversion between the two regimes occurs at mole fractions X- PEG(m --> h) approximate to 0.04, 0.01-0.02 and 0.005-0.01 for PEG-DPPE with mean PEG molecular masses of 350, 2000 and 5000 Da, respectively, as expected theoretically. Adsorption of HSA to DPPC membranes is detected as a decrease of the spin label 2.4(max) hyperfine splitting in the gel phase. Saturation is obtained at a protein/lipid ratio of ca. 1:1 w/w. In the presence of polymer-grafted lipids, HSA adsorbs to DPPC membranes only in the mushroom regime, irrespective of polymer length. In the brush regime, the spin-label values of 2A(max) are unchanged in the presence of protein. Even in the mushroom regime, protein adsorption progressively becomes strongly attenuated as a result of the steric stabilization exerted by the polymer lipid. These results are in agreement with theoretical estimates of the lateral pressure exerted by the grafted polymer in the brush and mushroom regimes, respectively. (C) 2002 Elsevier Science B.V. All rights reserved
Modelling and optimization of least-cost water distribution networks with multiple supply sources and users
The proper allocation of water resources is a very important practical problem in the field of water network planning. Optimization models that are expeditious and easy to use for all stakeholders of the sector play an important role for water resource management. The present work resumes and reviews a least-cost optimization model proposed by our group (Maiolo and Pantusa in Water Sci Tech-W Sup. https://doi.org/10.2166/ws.2015.114, 2016), able to design a water distribution network with multiple supply sources and multiple users. This approach requires of solving an optimization problem based on a nonlinear objective function which is proportional to the cost of the water distribution network. The cost of pre-existing pipelines is considered null. A more realistic scenario, able to consider the maximum flow rate allowed for existing sources-users connections, is considered here. In order to illustrate the usefulness and flexibility of the proposed approach, an application of the model to the real case of the province of Croton, Southern Italy, is presented