Practical issues in quantum-key-distribution postprocessing

Quantum key distribution (QKD) is a secure key generation method between two distant parties by wisely exploiting properties of quantum mechanics. In QKD, experimental measurement outcomes on quantum states are transformed by the two parties to a secret key. This transformation is composed of many logical steps (as guided by security proofs), which together will ultimately determine the length of the final secret key and its security. We detail the procedure for performing such classical postprocessing taking into account practical concerns (including the finite-size effect and authentication and encryption for classical communications). This procedure is directly applicable to realistic QKD experiments and thus serves as a recipe that specifies what postprocessing operations are needed and what the security level is for certain lengths of the keys. Our result is applicable to the BB84 protocol with a single or entangled photon source. © 2010 The American Physical Society.published_or_final_versio

Formulation and evaluation of silver nanoparticles as antibacterial and antifungal agents with a minimal cytotoxic effect

Preparation of non-biodegradable nonoparticles is a fast growing field,which is vital in both nanomedicine and nanotechnology applications.In this investigation, our attention will be focused on the preparationand evaluation of colloidal silver nanoparticles as antibacterial andantifungal agents. The colloidal silver nanoparticles have beenprepared employing standard chemical reduction methods. Thecolloidal silver nanoparticles were characterized using transmissionelectron microscopy TEM, zeta potential, photo correlationspectroscopy PCS, and in vitro release kinetics. The particles thusobtained were spherical in shape and having an average particles sizeof 5-20 nm , zeta potentials of -25.5 to -38.3 mV, and the releasekinetics was following zero order kinetics with r2>0.96. Thedissolution data indicates that the release of the silver nanoparticles isinversely correlated with the size of the nanoparticles i.e. the releaseincreased with smaller particles. The results suggest that the Ag NPswould be stable in the pharmaceutical preparations and will be easilyto the infection site. The colloidal silver nanoparticles were found tobe very efficient antibacterial agents for different types of bacteria.The bacteria studied were namely: E. coli, S. coccus, Salmonellae, andP. aeruginosa. The associated antifungal effects were also investigatedfor Aspergillus and Pencillium. . Cytotoxicity of the nanoparticle wasstudied using human fibroblast cell line. It was concluded thatcytotoxicity is concentrations dependant. The results provided strongevidence that could warrant the consideration of silver nanoparticles asantibacterial and antifungal agent that could circumvent the side andpassive effects of the conventional antibiotics.Keywords: Silver nanoparticles, antibacterial, antifungal, cytotoxicity, micro-plate assay, release kinetics

Mathematical Modelling of Chemical Diffusion through Skin using Grid-based PSEs

A Problem Solving Environment (PSE) with connections to remote distributed Grid processes is developed. The Grid simulation is itself a parallel process and allows steering of individual or multiple runs of the core computation of chemical diffusion through the stratum corneum, the outer layer of the skin. The effectiveness of this Grid-based approach in improving the quality of the simulation is assessed

Universally composable and customizable post-processing for practical quantum key distribution

In quantum key distribution (QKD), a secret key is generated between two distant parties by transmitting quantum states. Experimental measurements on the quantum states are then transformed to a secret key by classical post-processing. Here, we propose a construction framework in which QKD classical post-processing can be custom made. Though seemingly obvious, the concept of concatenating classical blocks to form a whole procedure does not automatically apply to the formation of a quantum cryptographic procedure since the security of the entire QKD procedure rests on the laws of quantum mechanics and classical blocks are originally designed and characterized without regard to any properties of these laws. Nevertheless, we justify such concept of concatenating classical blocks in constructing QKD classical post-processing procedures, along with a relation to the universal-composability-security parameter. Consequently, effects arising from an actual QKD experiment, such as those due to the finiteness of the number of signals used, can be dealt with by employing suitable post-processing blocks. Lastly, we use our proposed customizable framework to build a comprehensive generic recipe for classical post-processing that one can follow to derive a secret key from the measurement outcomes in an actual experiment. © 2010 Elsevier Ltd. All rights reserved.postprin

Nanosized rods agglomerates as a new approach for formulation of a dry powder inhaler

HF Salem1 ME Abdelrahim2 K Abo Eid3 MA Sharaf3,41Department of Pharmaceutics, 2Department of Clinical Pharmacy, Faculty of Pharmacy, The University of Beni Suef, Beni Suef; 3Department of Chemistry, Helwan University, Ain Helwan, Helwan, Egypt; 4Department of Chemistry, The American University in Cairo, New Cairo, Helwan 11835, EgyptBackground: Nanosized dry powder inhalers provide higher stability for poorly water-soluble drugs as compared with liquid formulations. However, the respirable particles must have a diameter of 1–5 µm in order to deposit in the lungs. Controlled agglomeration of the nanoparticles increases their geometric particle size so they can deposit easily in the lungs. In the lungs, they fall apart to reform nanoparticles, thus enhancing the dissolution rate of the drugs. Theophylline is a bronchodilator with poor solubility in water.Methods: Nanosized theophylline colloids were formed using an amphiphilic surfactant and destabilized using dilute sodium chloride solutions to form the agglomerates.Results: The theophylline nanoparticles thus obtained had an average particle size of 290 nm and a zeta potential of −39.5 mV, whereas the agglomerates were 2.47 µm in size with a zeta potential of −28.9 mV. The release profile was found to follow first-order kinetics (r2 > 0.96). The aerodynamic characteristics of the agglomerated nanoparticles were determined using a cascade impactor. The behavior of the agglomerate was significantly better than unprocessed raw theophylline powder. In addition, the nanoparticles and agglomerates resulted in a significant improvement in the dissolution of theophylline.Conclusion: The results obtained lend support to the hypothesis that controlled agglomeration strategies provide an efficient approach for the delivery of poorly water-soluble drugs into the lungs.Keywords: theophylline, nanoparticles, agglomerates, dry powder inhale

Electrochemical inhibition biosensor array for rapid detection of water pollutions based on bacteria immobilized on screen-printed gold electrodes

This work reports on the development of a bacteria-based inhibition biosensor array for detection of different types of pollutions, i.e. heavy metal ions (Zn 2+ ), pesticides (DDVP) and petro-chemicals (pentane), in water. The biosensor chip for preliminary identification of the above water pollutants is based on three types of bacteria (Escherichia coli, Shewanella oneidensis and Methylosinus trichosporium OB3b) immobilized on screen-printed gold electrode surface via poly L-lysine which provides strong adhesion of bacterial monolayer to the electrode without losses of biological function. A series of optical measurements and DC electrochemical measurements were carried out on these three types of bacteria species immobilized on modified screen printed gold electrodes as well as on the bacteria in solution samples. The principle of electrochemical detection of pollutants is based on the facts that live bacteria adsorbed (or immobilized) on the electrode surface appeared to be insulating and thus reducing the electrochemical current, while the bacteria damaged by pollutants are less insulating. The results obtained demonstrated different effects of the three different types of analytes studied, e.g. Zn 2+ , DDVP, and pentane, on the three bacteria used. The findings are encouraging for application of a pattern recognition approach for identification pollutants which may lead to development of a novel, simple, and cost-effective bio-sensing array for preliminary detection of environmental pollutants in water

Anomalies in the twist elastic behaviour of mixtures of calamitic and bent-core liquid crystals

The splay, twist and bend elastic constants (K11, K22 and K33) have been measured as a function of temperature in bent-core/calamitic mixtures based on three different calamitic materials (5CB, 8CB and ZLI1132) and two bent-core dopants. The behaviour of the splay and bend constants are as expected; a reduction in K33 of ~20%, in line with predictions from mixing rules and other observations. Interestingly, no change is seen in the splay constant, K11 of the calamitic hosts. Surprisingly though, the twist elastic constant exhibits a reduction of 30 – 40% in all mixtures across the nematic range, an effect not previously reported and much larger than mixing rules can explain. The elastic behaviour is universal in our mixtures. We explain part of the reduction in the twist deformation by considering the influence of the chiral conformer fluctuations of the bent-core molecules on the twist elastic constants of the mixtures. However, the dramatic reduction can only be fully explained by also including contributions from chiral conformer fluctuations of the calamitic host, a form of chiral amplification

Dietary and supplemental long-chain omega-3 fatty acids as moderators of cognitive impairment and Alzheimer’s disease

Purpose: There is an ever-growing body of literature examining the relationship between dietary omega-3 polyunsaturated fatty acids (ω3 PUFAs) and cerebral structure and function throughout life. In light of this, the use of ω3 PUFAs, namely, long-chain (LC) ω3 PUFAs (i.e., eicosapentaenoic acid and docosahexaenoic acid), as a therapeutic strategy to mitigate cognitive impairment, and progression to Alzheimer’s disease is an attractive prospect. This review aims to summarise evidence reported by observational studies and clinical trials that investigated the role of LC ω3 PUFAs against cognition impairment and future risk of Alzheimer’s disease. Methods: Studies were identified in PubMed and Scopus using the search terms “omega-3 fatty acids”, “Alzheimer’s disease” and “cognition”, along with common variants. Inclusion criteria included observational or randomised controlled trials (RCTs) with all participants aged ≥ 50 years that reported on the association between LC ω3 PUFAs and cognitive function or biological markers indicative of cognitive function linked to Alzheimer’s disease. Results: Evidence from 33 studies suggests that dietary and supplemental LC ω3 PUFAs have a protective effect against cognitive impairment. Synaptic plasticity, neuronal membrane fluidity, neuroinflammation, and changes in expression of genes linked to cognitive decline have been identified as potential targets of LC ω3 PUFAs. The protective effects LC ω3 PUFAs on cognitive function and reduced risk of Alzheimer’s disease were supported by both observational studies and RCTs, with RCTs suggesting a more pronounced effect in individuals with early and mild cognitive impairment. Conclusion: The findings of this review suggest that individuals consuming higher amounts of LC ω3 PUFAs are less likely to develop cognitive impairment and that, as a preventative strategy against Alzheimer’s disease, it is most effective when dietary LC ω3 PUFAs are consumed prior to or in the early stages of cognitive decline