A Fuzzy Petri Net for Pattern Recognition: Application to Dynamic Classes

When involving evolutionary natural objects, the odeling of dynamic lasses is the main issue for a pattern recognition system. This problem an be avoided by making dynamic the syste of pattern recognition which an then enter into various states according to the evolution of the lasses. We propose a dynamic recognition system founded on two types of learning. The static aspect of the learning is ensured by lassifiers or systems of lassifiers, while the dynamic aspect is translated by the learning of the planning of the various states by a fuzzy Petri net. The method is sucessfully applied to a synthetic data set. Received 21 September 2000 / Revised 19 December 2000 / Accepted in revised form 1 March 2001     

Production and characterisation of enzymatically produced lauric acid esters of fructose

Lauric acid esters of fructose were produced using immobilised lipase (EC 3.1.1.3; Novozym 435). A molecular sieve was used to shift the reaction towards the synthesis. The mono‐, di‐ and higher esters of lauric acid with fructose were obtained and analysed qualitatively and quantitatively by high‐pressure liquid chromatography (HPLC). At a 5:1 molar ratio of lauric acid to fructose the amounts of monoester, diester and higher esters produced were 37, 53 and 98 mg respectively after 96 h of reaction time. After purification of the products by column chromatography the hydrophile/lipophile balance (HLB) values of fructose monolaurate and fructose dilaurate were found to be 8.95 and 5.3 respectively and their critical micelle concentration (CMC) values were calculated as 7.20 × 10^?5 and 6.40 × 10^?5 M respectively. The CMC values of esters obtained from the conductivity curve and the surface tension curve were significantly (P < 0.05) similar to each other. It was found that when the concentration of surfactant was increased from 0.25 to 0.50% (w/v), stabilisation of the emulsion also increased. Fructose dilaurate showed better stability than the other esters. Separation of the phases reached 70% within 30 h for the emulsion prepared with 0.50% (w/v) of this ester. © 2002 Society of Chemical Industry     

Photoluminescence from germanium quantum wells and quantum dots in silicon grown by MBE at low temperature

Semiconductors - The low-temperature (T=2 K) photoluminescence (PL) has been studied in Si/Ge structures grown by MBE at a low (250–350°C) temperature of Ge deposition. The luminescence...     

Electrochemical determination of HIV drug Abacavir based on its reduction

Abacavir (I), a drug used in the treatment of HIV, is electrochemically reduced at the dropping mercury electrode in a four-electron process, similar to structurally related adenine (III) and adenosine triphosphate (IV). To undergo the reduction, the species is protonated in the vicinity of the electrode. The protonations take place on the 6-amino group and on one of the pyrimidine ring nitrogens. The role of covalent hydration of the pyrymidine ring has been interpreted. Best suited as supporting electrolytes for analytical purposes are solutions of 0.1-1.0 M sulfuric, perchloric, or hydrochloric acids. Procedures of analyses of tablets containing I were established and validated, based on peak currents obtained by linear sweep, differential pulse, or square-wave voltammetry with a hanging mercury drop electrode as indicator electrode. The procedure proved to be more sensitive and more reliable than that based on oxidation on a glassy carbon electrode, proposed previously.     

Conformational changes during protein adsorption. FT-IR spectroscopic imaging of adsorbed fibrinogen layers

The influence of hydrophobicity of the substrate surface on structural changes during protein adsorption was investigated. Plasma fibrinogen was chosen to model this effect as it is the most important protein in the body that adsorbs to foreign surfaces. Only conformations of adsorbed fibrinogen similar to that of the protein in solution do not activate the process of blood coagulation. Small spots on the substrate surface with conformational changes within the adsorbed protein are already sufficient to deteriorate biocompatibility. Mid-infrared hyperspectral imaging permits the identification of coagulated spots down to a few micrometers in size. The spectra of the FT-IR images that were assessed to be of suitable quality were clustered by a fuzzy c-means algorithm. The determination of the appropriate number of clusters was based on cluster variance. Subsequent evaluation of the centroid spectra of each cluster showed that their amide I band was separated into contributions from different structural units, with the alpha-helix content always being dominant. Significant differences between hydrophobic and hydrophilic surfaces were observed for turn and sheet contributions. Lower sheet/turn ratios appear to indicate inferior biocompatibility. Spots on hydrophilic surfaces could be identified, which exhibit structural changes similar to those on hydrophobic surfaces.     

Hydrogen generation from the dehydrogenation of ammonia–borane in the presence of ruthenium(III) acetylacetonate forming a homogeneous catalyst

Starting with ruthenium(III) acetylacetonate a homogeneous catalyst is formed which catalyzes the release of 1 equivalent of hydrogen gas from the dehydrogenation of ammonia–borane in toluene solution at low temperature in the range 50–65 °C. Mercury poisoning experiments showed that the catalytic dehydrogenation of ammonia–borane starting with ruthenium(III) acetylacetonate is a homogeneous catalysis. The final product obtained after the catalytic dehydrogenation of ammonia borane was thoroughly characterized by using ¹¹B Nuclear Magnetic Resonance and Infrared spectroscopies. The homogeneous catalyst formed from the reduction of ruthenium(III) acetylacetonate provides 950 turnovers (TTO) over 58 h and 27 (mol H₂)(mol Ru)⁻¹(h)⁻¹ value of initial turnover frequency (TOF) in hydrogen generation from the dehydrogenation of ammonia–borane at 60 °C before deactivation. Kinetics of this homogenous catalytic dehydrogenation of ammonia–borane was studied depending on the catalyst concentration, substrate concentration, and temperature. The hydrogen generation was found to be first order with respect to both the substrate concentration and catalyst concentration. The activation parameters of this reaction were also determined from the evaluation of the kinetic data: activation energy; E_a = 48 ± 2 kJ mol⁻¹, the enthalpy of activation; ΔH^# = 45 ± 2 kJ mol⁻¹ and the entropy of activation ΔS^# = −152 ± 5 J mol⁻¹ K⁻¹.     

Formulation and In Vitro Evaluation of Bisphosphonate Loaded Microspheres for Implantation in Osteolysis

ABSTRACT

Chitosan and poly(lactide-co-glycolide) acid (PLGA) microspheres loaded with alendronate sodium (AS) were prepared for orthopedic as well as dental applications. In orthopedics the aim was to make the total joint prostheses stay in the body for a long time without causing bone tissue loss, while in dentistry it was aimed to treat the alveolar bone resorption caused by periodontitis and also to make the dental treatment using implants easier by reducing the bone loss in patients with osteoporosis. Solvent evaporation method was used to prepare AS loaded PLGA microspheres and emulsion polimerization method was used to prepare AS loaded chitosan microspheres. Particle size, loading efficacy, surface characteristics, and in vitro release characteristics were examined on prepared formulations. After the examination of the scanning electron microscopy photographs of microspheres, chitosan microspheres were observed to have spherical structure and smooth surface characteristics while PLGA microspheres were observed to have spherical porous surface structure. Loading efficacy was found to be 3.30% for chitosan microspheres and 7.70% for PLGA microspheres. It was observed that 85% of AS had been released at the end of the third day from chitosan microspheres whereas 58% was released at the end of the fifth day from PLGA microspheres. It was found that chitosan microspheres gave first order release while PLGA microspheres gave zero order release.     

4-Aminophenyl boronic acid modified gold platforms for influenza diagnosis

As a potential pandemic threat to human health, there has been an urgent need for rapid, sensitive, simpler and less expensive detection method for the highly pathogenic influenza A virus. For this purpose, Quartz Crystal Microbalance (QCM) and Surface Plasmon Resonance (SPR) sensors have been developed for the recognition of hemagglutinin (HA) which is a major protein of influenza A virus. 4-Aminophenyl boronic acid (4-APBA) has been synthesized and used as a new ligand for binding of sialic acid (SA) via boronic acid–sugar interaction. SA has an important role in binding of HA. QCM and SPR sensor surfaces have been modified with thiol groups and then 4-APBA and SA have been immobilized on sensor surfaces, respectively. Sensor surfaces have been screened with AFM and used for the determination of HA from aqueous solution. The selective recognition of the QCM and SPR sensors toward Concanavalin A has been reported in this work. Also, the binding capacity and detection limits of QCM and SPR sensors have been calculated and detection limits were found to be 4.7 × 10^? 2 μM, (0.26 μg ml^? 1) and 1.28 × 10^? 1 μM, (0.72 μg ml^? 1) in the 95% confidence interval, respectively.     

Simultaneous depletion of albumin and immunoglobulin G by using twin affinity magnetic nanotraps

For biomarker discovery, simultaneous removal of albumin and immunoglobulin G (IgG) become more important for both concentrating other species including potential biomarkers and getting rid of their masking effect. In this study, we have proposed a covalent and photosensitive cross-linking conjugation of the biomolecules on nanostructures for the depletion of target proteins from aqueous solution and serum. The effect of concentration, pH, temperature and ionic strength on the adsorption of twin affinity nanotraps based on Cibacron Blue F3GA and Protein A were investigated. The efficiency of albumin and IgG depletion from human serum was performed using sodium dodecylsulfate–polyacrylamide gel electrophoresis.     

Erythromycin residue in honey from the Southern Marmara region of Turkey

Honey samples, collected from the Southern Marmara region of Turkey, were analysed for erythromycin residues by liquid chromatography–mass spectrometry using electrospray ionization in the positive ion mode (LC–ESI–MS). Fifty samples, comprising chestnut, pine, linden and multi-flower honeys, were collected directly from hives and analyzed. The limit of detection and quantification were 6 and 20 ng g^?1, respectively, and recovery ranged from 85 to 89%. Four of the honey samples (8%) were found to be contaminated with erythromycin residues at concentrations ranging from 50 to 1776 ng g^?1. An erythromycin-fortified cake feeding assay was also performed in a defined hive to test the transfer of erythromycin residue to the honey matrix. In this test hive, the residue level in the honey, 3 months after dosing, was approximately 28 ng g^?1.