Catalytic esterolysis of p-nitrophenyl esters by optically active polymeric oximes

An optically active polymer containing oxime groups was prepared by partial quaternization of a copolymer of 4-vinyl pyridine and (+)(S)-4-methyl-1-hexen-3-one, with phenacyl bromide and subsequent reaction with hydroxylamine hydrochloride. This polymer was used as a catalyst for the esterolysis of esters of p-nitrophenol with aliphatic and aromatic carboxylic acids characterized by different steric and hydrophobic features. The detailed evaluation of kinetic parameters permitted identification of the main factors responsible for the catalytic behaviour.     

A simplified approach to the performance evaluation of FDMA‐CDMA systems

This work shows it is possible to apply for the performance evaluation of FDMA‐CDMA cellular mobile systems a simple analytical approximated method, previously successfully proposed by two of the authors with reference to FDMA‐TDMA systems. The distinctive feature of the methodology we describe is that it allows for an immediate determination of both the indexes traditionally employed to define system performance, i.e., average bit error probability _e and outage probability P _out at a very low computational cost. The hypothesis required to apply the proposed approximation is that the examined spread spectrum system be characterized by a bandwidth occupancy lower than the coherence bandwidth of the transmission channel. This could be the case of a wireless DS‐CDMA system envisioned to provide voice service and exploiting a processing gain of the order of a hundred. We apply our methodology to determine the performance improvements in both _e and P _out introduced increasing the protection of the transmitted information through error correcting codes and interleaving, in different operating conditions as regards the functioning of the power control loops. A comparison is also satisfyingly carried out with some other approximated analytical methods found in literature. We strongly point out that the corresponding results are achieved at a much more modest computational cost than in traditional approaches. This revised version was published online in July 2006 with corrections to the Cover Date.     

Square-free algorithms in positive characteristic

We study the problem of the computation of the square-free decomposition for polynomials over fields of positive characteristic. For fields which are explicitly finitely generated over perfect fields, we show how the classical algorithm for characteristic zero can be generalized using multiple derivations. For more general fields of positive characteristic one must make an additional constructive hypothesis in order for the problem to be decidable. We show that Seidenberg'sCondition P gives a necessary and sufficient condition on the fieldK for computing a complete square free decomposition of polynomials with coefficients in any finite algebraic extension ofK.This research was partially supported by C.N.R., M.U.R.S.T, CEC contract ES PRIT B.R.A.n.6846 POSSO and EC Science Plan Project Computational Methods in the Theory of Riemann Surfaces and Algebraic Curves     

Information fusion for anomaly detection with the dendritic cell algorithm

Dendritic cells are antigen presenting cells that provide a vital link between the innate and adaptive immune system, providing the initial detection of pathogenic invaders. Research into this family of cells has revealed that they perform information fusion which directs immune responses. We have derived a dendritic cell algorithm based on the functionality of these cells, by modelling the biological signals and differentiation pathways to build a control mechanism for an artificial immune system. We present algorithmic details in addition to experimental results, when the algorithm was applied to anomaly detection for the detection of port scans. The results show the dendritic cell algorithm is successful at detecting port scans.     

A Certified Proof of the Cartan Fixed Point Theorems

In this paper we present a machine-certified proof for the Cartan Fixed Point Theorems in the univariate case, using the HOL Light theorem prover.     

Ethylene homo- and copolymerization over MgCl2-TiCl4 catalysts: Polymerization kinetics and polymer particle morphology

Three procatalysts of the MgCl₂/TiCl₄ type, differing mainly in their morphological characteristics, were investigated in ethylene polymerization and ethylene-1-butene copolymerization. Apparently, hydrogen has an intrinsic and general deactivating effect but it can also play an activating effect in homopolymerization. This peculiarity was found to be related to a catastrophic breakage of the polymer/catalyst particles during growth and thus to the exposure of new active centers. In this case the kinetic profiles are irregular and characterized by one or more secondary peaks which reflect the moment when this morphology-driven rate-enhancement effect takes place. In general, the prepolymerization of the procatalysts with propylene tends to slightly enhance homopolymerization rate, to slow down copolymerization rate and to stabilize the morphology of the growing polymer particles, thus preventing the occurrence of the irregular kinetic profiles observed during homopolymerization in the presence of hydrogen. The behavior of the procatalysts investigated was found to depend on the distribution of their pore size rather than the absolute values of their porosity. Likely this is due to an easier diffusion of the monomer and a more regular and homogeneous growth of the polymer within larger as opposed to smaller pores. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Combination of Polymer Technology and Carbon Nanotube Array for the Development of an Effective Drug Delivery System at Cellular Level

In this article, a carbon nanotube (CNT) array-based system combined with a polymer thin film is proposed as an effective drug release device directly at cellular level. The polymeric film embedded in the CNT array is described and characterized in terms of release kinetics, while in vitro assays on PC12 cell line have been performed in order to assess the efficiency and functionality of the entrapped agent (neural growth factor, NGF). PC12 cell differentiation, following incubation on the CNT array embedding the alginate delivery film, demonstrated the effectiveness of the proposed solution. The achieved results indicate that polymeric technology could be efficiently embedded in CNT array acting as drug delivery system at cellular level. The implication of this study opens several perspectives in particular in the field of neurointerfaces, combining several functions into a single platform.     

Expanding Horizons in the Validation of GMO Analytical Methods: Fuzzy-based Expert Systems

Validation is the process establishing the suitability of an analytical method for a particular purpose. Various guidelines defining statistical procedures for validation of chemical, bio-chemical, pharmaceutical, and molecular methods have been developed, and ad hoc validation metrics (indices and test statistics) are available and routinely used, for in-house and interlaboratory testing and decision making. However, there is no universally accepted practice for assay validation, and often, subjectivity plays an important role in the interpretation of validation studies’ results. Instead, the key to rational validation studies relies upon the formalization and harmonization of procedures for their design and interpretation of results. Fuzzy-based techniques can be helpful in such respect. Fuzzy logic allows summarizing the information obtained by classic independent validation statistics into one synthetic index of overall method performance. The possibility of having a comprehensive indicator of method performance has the advantage of permitting direct method comparison, facilitating the evaluation of many individual, possibly contradictory metrics. The objectives of this paper are to illustrate the advantages that a fuzzy-based aggregation method could bring into the validation of analytical methods and to propose its application for the evaluation of methods’ performance. Validation metrics are compared for practical examples of assessment of method performance in collaborative studies. Fuzzy logic-based rules are shown to be applicable to improve insights into method quality and interpretation of results.     

Comparison of the characterisation of the fruit‐like aroma of Teucrium flavum L. subsp flavum by hydrodistillation and solid‐phase micro‐extraction

BACKGROUND: Teucrium species (Lamiaceae) are interesting for the food industry since many of them are used in the preparation of flavoured wines and beers, herbal teas, bitters and liqueurs. On this basis, the analysis of the aroma components of Teucrium flavum L. subsp. flavum growing in central Italy was carried out by means of both hydrodistillation (HD) and headspace solid‐phase micro‐extraction (HS‐SPME), coupled with GC/FID and GC/MS. RESULTS: A total of 102 components were identified in the essential oils, representing 99.0‐99.3% of the total oils. Sesquiterpenes hydrocarbons constituted the major fraction (48.5–49.4%), with the apple‐like flavour (Z,E)‐α‐farnesene being the major component. HS‐SPME allowed the analysis of the volatiles not only emitted by specific plant parts, but also by different parts within a single flower: flower calyx afforded the highest contribution, in terms of volatiles, to the aroma of the plant. CONCLUSION: The chemical profile of the volatile fraction obtained by HD and HS‐SPME, demonstrated the plant fruit‐like aroma, confirming the usefulness for flavouring wines, bitters and other kind of beverages, and also suggested other applications, as aroma and taste enhancer in food processing. In particular, SPME resulted in a very useful technique, which permits a choice between the part of the plant which has the highest concentration of a specific fragrance, and therefore establishes the best way of sampling during industrial applications of aromatic plants. Copyright © 2009 Society of Chemical Industry     

An improved PID switching control strategy for type 1 diabetes

In order for an "artificial pancreas" to become a reality for ambulatory use, a practical closed-loop control strategy must be developed and validated. In this paper, an improved PID control strategy for blood glucose control is proposed and critically evaluated in silico using a physiologic model of Hovorka et al. [1]. The key features of the proposed control strategy are: 1) a switching strategy for initiating PID control after a meal and insulin bolus; 2) a novel time-varying setpoint trajectory; 3) noise and derivative filters to reduce sensitivity to sensor noise; and 4) a practical controller tuning strategy. Simulation results demonstrate that proposed control strategy compares favorably to alternatives for realistic conditions that include meal challenges, incorrect carbohydrate meal estimates, changes in insulin sensitivity, and measurement noise.