17,225 research outputs found
Structure and dynamics of water at carbon-based interfaces
Water structure and dynamics are affected by the presence of a nearby interface. Here,
first we review recent results by molecular dynamics simulations about the effect of different carbon-based materials, including armchair carbon nanotubes and a variety of graphene sheets—flat and with corrugation—on water structure and dynamics. We discuss the calculations of binding energies, hydrogen bond distributions, water’s diffusion coefficients and their relation with surface’s geometries at different thermodynamical conditions. Next, we present new results of the crystallization and dynamics of water in a rigid graphene sieve. In particular, we show that the
diffusion of water confined between parallel walls depends on the plate distance in a non-monotonic way and is related to the water structuring, crystallization, re-melting and evaporation for decreasing inter-plate distance. Our results could be relevant in those applications where water is in contact with nanostructured carbon materials at ambient or cryogenic temperatures, as in man-made superhydrophobic materials or filtration membranes, or in techniques that take advantage of hydrated graphene interfaces, as in aqueous electron cryomicroscopy for the analysis of proteins adsorbed on graphene.Postprint (author's final draft
Hierarchical Role-Based Access Control with Homomorphic Encryption for Database as a Service
Database as a service provides services for accessing and managing customers
data which provides ease of access, and the cost is less for these services.
There is a possibility that the DBaaS service provider may not be trusted, and
data may be stored on untrusted server. The access control mechanism can
restrict users from unauthorized access, but in cloud environment access
control policies are more flexible. However, an attacker can gather sensitive
information for a malicious purpose by abusing the privileges as another user
and so database security is compromised. The other problems associated with the
DBaaS are to manage role hierarchy and secure session management for query
transaction in the database. In this paper, a role-based access control for the
multitenant database with role hierarchy is proposed. The query is granted with
least access privileges, and a session key is used for session management. The
proposed work protects data from privilege escalation and SQL injection. It
uses the partial homomorphic encryption (Paillier Encryption) for the
encrypting the sensitive data. If a query is to perform any operation on
sensitive data, then extra permissions are required for accessing sensitive
data. Data confidentiality and integrity are achieved using the role-based
access control with partial homomorphic encryption.Comment: 11 Pages,4 figures, Proceedings of International Conference on ICT
for Sustainable Developmen
Estoicos en la Sevilla del XVI: un poema en falecios del licenciado Francisco Pacheco a Pedro Vélez de Guevara
Edición crÃtica, traducción y estudio de un poema inédito en falecios del licenciado Francisco Pacheco a Pedro Vélez de Guevara ("At tibi male sit, grauedo iniqua..."). Datable en 1573, la composición, que imita a Catulo, documenta el importante papel de emisor y receptor en la introducción del estoicismo en Sevilla
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