Rheological and drug‐release behaviour of a scleroglucan gel matrix at different drug loadings

The aim of this study was to investigate the drug‐loading effects on release and mechanical properties of a scleroglucan gel, with the intention of considering them in delivery systems formulations. The rheological and kinetic properties of a 2 % w/w scleroglucan gel matrix loaded with 0, 0.02, 0.04, 0.06, 0.2 and 0.4 % w/w of theophylline (Th, used as a model drug) were investigated. Rheological measurements were performed in a controlled‐stress rotational‐shear rheometer under isothermal conditions. For theophylline release from the gel a flat Franz cell was used and the kinetic parameters were derived applying a semi‐empirical power law. The influence of scleroglucan molar weight on kinetic and rheological behaviour was also studied. Results suggest two possible effects of drug loading on the gel network: in the 0.04–0.06 % w/w Th range a plasticizing effect and in the 0.2–0.4 % w/w Th range a rigidization effect. In the first range mentioned, the changes in the gel structural properties tested by means of rheological measurements are coincident with changes in drug‐release kinetics. Copyright © 2005 Society of Chemical Industry     

Synthesis and characterization of functional gradient copolymers of glycidyl methacrylate and butyl acrylate

Epoxy-functional spontaneous gradient copolymers of glycidyl methacrylate (G) and n-butyl acrylate (B) were synthesized via atom transfer radical polymerization (ATRP). The copolymerization reactions were carried out in toluene solution at 70 °C, using methyl 2-bromopropionate (MBrP) as initiator and copper chloride with N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA) as the catalyst system. The kinetic behaviour of the statistical copolymerizations was studied in a wide composition interval with molar fractions of G ranging from 0.10 to 0.75. The synthesized copolymers were characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. ¹H NMR was employed to determine the copolymer composition, demonstrating the gradient character of the copolymers along the main chain in the whole monomer conversion interval. Apart from this, the sequence distribution and stereoregularity were analyzed. These microstructural experimental data agreed well with those calculated from Mayo-Lewis terminal model (MLTM) and a Bernoullian statistic with an isotacticity parameter of σ_G = 0.28 and a coisotacticity parameter of σ = 0.30.     

200°C, 96-nm wavelength range, continuous-wave lasing fromunbonded GaAs MOVPE-grown vertical cavity surface-emitting lasers

We report record temperature and wavelength range attained using MOVPE-grown AlGaAs vertical cavity surface-emitting lasers (VCSEL's). Unbonded continuous-wave lasing is achieved at temperatures up to 200°C from these top-emitting VCSEL's and operation over a 96-nm wavelength regime near 850 nm is also achieved from the same nominal design. Temperature and wavelength insensitive operation is also demonstrated; threshold current is controlled to within a factor of 2 (2.5-5 mA) for a wavelength range exceeding 50 nm and to within ±30% (5-10 mA) for a temperature range of 190°C at 870 nm     

Automatic verification of concurrent stochastic systems

Formal Methods in System Design - Automated verification techniques for stochastic games allow formal reasoning about systems that feature competitive or collaborative behaviour among rational...     

Food-water security and virtual water trade in the Middle East and North Africa

The purpose of this study is to analyze the political economy of food-water security in the water-scarce Middle East and North Africa region. The study deploys the lens of virtual water trade to determine how the region's economies have met their rising food-water requirements over the past three decades. It is shown that the region's water and food security currently depend to a considerable extent on water from outside the region, ‘embedded’ in food imports and accessed through trade. The analysis includes blue (surface and groundwater) and green water resources.     

Titans’ revenge: Detecting Zeus via its own flaws

Malware is one of the main threats to the Internet security in general, and to commercial transactions in particular. However, given the high level of sophistication reached by malware (e.g. usage of encrypted payload and obfuscation techniques), malware detection tools and techniques still call for effective and efficient solutions. In this paper, we address a specific, dreadful, and widely diffused financial malware: Zeus.The contributions of this paper are manifold: first, we propose a technique to break the encrypted malware communications, extracting the keystream used to encrypt such communications; second, we provide a generalization of the proposed keystream extraction technique. Further, we propose Cronus, an IDS that specifically targets Zeus malware. The implementation of Cronus has been experimentally tested on a production network, and its high quality performance and effectiveness are discussed. Finally, we highlight some principles underlying malware—and Zeus in particular—that could pave the way for further investigation in this field.     

Coreference resolution: an empirical study based on SemEval-2010 shared Task 1

This paper presents an empirical evaluation of coreference resolution that covers several interrelated dimensions. The main goal is to complete the comparative analysis from the SemEval-2010 task on Coreference Resolution in Multiple Languages. To do so, the study restricts the number of languages and systems involved, but extends and deepens the analysis of the system outputs, including a more qualitative discussion. The paper compares three automatic coreference resolution systems for three languages (English, Catalan and Spanish) in four evaluation settings, and using four evaluation measures. Given that our main goal is not to provide a comparison between resolution algorithms, these are merely used as tools to shed light on the different conditions under which coreference resolution is evaluated. Although the dimensions are strongly interdependent, making it very difficult to extract general principles, the study reveals a series of interesting issues in relation to coreference resolution: the portability of systems across languages, the influence of the type and quality of input annotations, and the behavior of the scoring measures.     

Morphology and structure of the pollen cone and pollen grain of the Araucaria species from Argentina

The pollen cone and the pollen grain of the two Argentinean species of Araucaria are described with LM, SEM and TEM. Primordia of pollen cones are formed in April and May and reach maturity by mid-October in A. angustifolia (Bert.) O. Kuntze and by mid-November in A. araucana. (Mol.) K. Koch. Characters of the mature pollen cones and microsporophylls between both taxa are clearly differentiated. Pollen grains are spheroidal-subspheroidal, inaperturate, and asaccate with granulate exine and a subequatorial annular area that corresponds to the sexine thickness. Sculpturing consists of irregularly dispersed granules that are sometimes fused to each other (A. angustifolia) or forming microrugulae (A. araucana). Microgranules and microspinules are also present. The pollen wall ultrastructure is formed by a granular ectexine and lamellated endexine. Granular elements in A. angustifolia are more loosely disposed, form more interstices, and are gradually smaller towards the endexine than in A. araucana. To asses the probable relationships within the family, we compared the pollen grains of the two Araucaria species with those of other extant genera (Agathis, Wollemia) and also with fossil pollen (Araucariacites, Balmeiopsis, Cyclusphaera, Dilwynites) attributed to Araucariaceae.