An Optimization Approach to Petri Net Monitor Design

This note addresses the problem of enforcing generalized mutual exclusion constraints on a Petri net plant. First, we replace the classical partition of the event set into controllable and uncontrollable events from supervisory control theory, by associating a control and observation cost to each event. This leads naturally to formulate the supervisory control problem as an optimal control problem. Monitor places which enforce the constraint are devised as a solution of an integer linear programming problem whose objective function is expressed in terms of the introduced costs. Second, we consider timed models for which the monitor choice may lead to performance optimization. If the plant net belongs to the class of mono-T-semiflow nets, we present an integer linear fractional programming approach to synthesize the optimal monitor so as to minimize the cycle time lower bound of the closed loop net. For strongly connected marked graphs the cycle time of the closed-loop net can be minimized     

Comparative chemical composition,antioxidant and hypoglycaemic activities of Juniperus oxycedrus ssp. oxycedrus L. berry and wood oils from Lebanon

Juniper (Juniperus oxycedrus) is used in European cuisine for its distinguishing flavour. J. oxycedrus ssp. oxycedrus berry and wood essential oils were tentatively identified by GC and GC/MS. Fifty compounds were identified in the berry oil and 23 compounds were identified in the wood oil. The J. oxycedrus ssp. oxycedrus berry oil was characterised by high contents of α-pinene (27.4%) and β-myrcene (18.9%). Other important compounds were α-phellandrene (7.1%), limonene (6.7%), epi-bicyclosesquiphellandrene (2.3%) and δ-cadinene (2.2%) while, in the wood oil, δ-cadinene (14.5%) is a major main component, together with cis-thujopsene (9.2%) and α-muurolene (4.9%). In vitro evaluation of antioxidant activity by the DPPH method showed a significant activity for both oils with IC₅₀ values of 1.45 μl/ml for wood and 7.42 μl/ml for berries. Hypoglycaemic activity was investigated through the inhibition of α-amylase. The results revealed that oil obtained by hydrodistillation from J. oxycedrus ssp. oxycedrus wood exhibits an interesting activity with IC₅₀ of 3.49 μl/ml.     

Experimental characterization and numerical analysis of the 4H-SiC p-i-n diodes static and transient behaviour

Steady-state and turn-off switching characteristics of aluminium-implanted 4H-SiC p-i-n diodes designed for high-current density operation, are investigated experimentally and by mean of numerical simulations in the 298-523 K temperature range. The diodes present circular structure with a diameter of 350 μm and employ an anode region with an aluminium depth profile peaking at 6×10¹⁹ cm⁻³ at the surface. The profile edge and the junction depth are located at 0.2 and 1.35 μm, respectively. At room temperature the measured forward current density is close to 370 A/cm² at 5 V with an ideality factor always less than 2 before high-current injection or device-series resistance became dominant. The transient analysis reveals a strong potential of this diodes for use in high-speed, high-power applications, especially at high temperature, with a very low turn-off recovery time (<80 ns) in the whole range of test conditions. The simulated results match the experimental data, showing that the switching performance is mainly due to the poor minority charge carrier lifetime estimated to be 15 ns for these implanted devices.     

Protein content and gluten quality of durum wheat (Triticum turgidum subsp. durum) as affected by sowing date

The end use quality of durum wheat is sensitive to the environmental conditions pertaining before and during grain filling, and can therefore be modified by manipulation of cultivar and sowing date. A field trial was carried out to study the effect on protein content and gluten quality of varying both sowing date (October, December and March) and cultivar (Simeto, Colosseo and Creso). A delay in sowing date was associated with a decrease in mean grain weight, but not in grain nitrogen content, thus leading to an overall increase from 10.7 to 14.7% in grain protein percentage. Independent of sowing date, over 78% of the grain nitrogen was derived from re‐translocation from vegetative tissue. The similar amounts of nitrogen accumulated in each grain at maturity were set by the similarity in the amount of nitrogen available at anthesis. The observed increase in protein percentage partly explained the greater dough strength (alveographic W) observed in material harvested from the latest sowing. The gluten index, on the other hand, decreased as sowing was delayed. Given the parallel increase in glutenin percentage, we propose that temperatures above 30 °C at the end of the grain filling period have a negative effect on the gluten polymerisation process. Copyright © 2007 Society of Chemical Industry     

Modelling the relationship between tensile strength and porosity in bioceramic scaffolds

A model describing the relationship between tensile strength and total porosity in brittle open-cell macroporous foams is developed and applied to silicate ceramic scaffolds produced by sponge replication and subsequent sinter-crystallization. The tensile strength of the scaffolds decreased from 7.4 to 2.3 MPa as the total porosity increased from 0.40 to 0.79. The results of the model, which is based on the concepts of fracture mechanics, were in good agreement with the experimental data (R² = 0.88), which supports the good predictive capability of the approach presented. In principle, this model could help biomaterials scientists not only to estimate the tensile strength of highly-porous bioactive glass and ceramic scaffolds, which is often difficult to determine experimentally, but also to improve the rational design of porous bioceramics with customized properties.     

The Ketogenic Diet Reduces the Harmful Effects of Stress on Gut Mitochondrial Biogenesis in a Rat Model of Irritable Bowel Syndrome

Functional alterations in irritable bowel syndrome have been associated with defects in bioenergetics and the mitochondrial network. Effects of high fat, adequate-protein, low carbohydrate ketogenic diet (KD) involve oxidative stress, inflammation, mitochondrial function, and biogenesis. The aim was to evaluate the KD efficacy in reducing the effects of stress on gut mitochondria. Newborn Wistar rats were exposed to maternal deprivation to induce IBS in adulthood. Intestinal inflammation (COX-2 and TRL-4); cellular redox status (SOD 1, SOD 2, PrxIII, mtDNA oxidatively modified purines); mitochondrial biogenesis (PPAR-γ, PGC-1α, COX-4, mtDNA content); and autophagy (Beclin-1, LC3 II) were evaluated in the colon of exposed rats fed with KD (IBD-KD) or standard diet (IBS-Std), and in unexposed controls (Ctrl). IBS-Std rats showed dysfunctional mitochondrial biogenesis (PPAR-γ, PGC-1α, COX-4, and mtDNA contents lower than in Ctrl) associated with inflammation and increased oxidative stress (higher levels of COX-2 and TLR-4, SOD 1, SOD 2, PrxIII, and oxidatively modified purines than in Ctrl). Loss of autophagy efficacy appeared from reduced levels of Beclin-1 and LC3 II. Feeding of animals with KD elicited compensatory mechanisms able to reduce inflammation, oxidative stress, restore mitochondrial function, and baseline autophagy, possibly via the upregulation of the PPAR-γ/PGC-1α axis.     

Determination of the Synthetic Cannabinoids JWH-122, JWH-210, UR-144 in Oral Fluid of Consumers by GC-MS and Quantification of Parent Compounds and Metabolites by UHPLC-MS/MS

The consumption of synthetic cannabinoids (SCs) has significantly increased in the last decade and the analysis of SCs and their metabolites in human specimens is gaining interest in clinical and forensic toxicology. A pilot study has been carried out using a combination of an initial last generation gas chromatography-mass spectrometry (GC-MS) screening method for the determination of JWH-122, JWH-210, UR-144) in oral fluid (OF) of consumers and an ultra-high performance liquid chromatography high resolution mass spectrometry (UHPLC-HRMS) confirmatory method for the quantification of the parent compounds and their metabolites in the same biological matrix. OF samples were simply liquid-liquid extracted before injecting in both chromatographic systems. The developed methods have been successfully validated and were linear from limit of quantification (LOQ) to 50 ng/mL OF. Recovery of analytes was always higher than 70% and matrix effect always lower than 15% whereas intra-assay and inter-assay precision and accuracy were always better than 16%. After smoking 1 mg JWH-122 or UR-144 and 3 mg JWH-210, maximum concentration of 4.00–3.14 ng/mL JWH-122, 8.10–7.30 ng/mL JWH-210 ng/mL and 7.40 and 6.81 ng/mL UR-144 were measured by GC-MS and UHPLC-HRMS respectively at 20 min after inhalation. Metabolites of JWH 122 and 210 were quantified in OF by UHPLC-HRMS, while that of UR144 was only detectable in traces. Our results provide for the first time information about disposition of these SCs and their metabolites in consumers OF. Last generation GC-MS has proven useful tool to identify and quantify parent SCs whereas UHPLC-HRMS also confirmed the presence of SCs metabolites in the OF of SCs consumers.     

Optimizing acido-basic profile of support in Ni supported La2O3+Al2O3 catalyst for dry reforming of methane

The increasing alarm of global warming always draws interest in reactions like dry reforming of methane (DRM) where both global warming gases (CO₂ and CH₄) are converted into value-added chemical building blocks, such as syngas. Nickel catalyst active sites along with support acid-base profiles play a key role in DRM. Herein, xLa₂O₃+(100-x) Al₂O₃ (x = 0, 10, 15, 20%) supports are prepared and followed by NiO dispersion over the produced support by impregnation method. It was tested for DRM reaction and characterized with TGA, XRD, TEM, IR, Surface area and porosity measurement, H₂-TPR, CO₂-TPD and NH₃-TPD techniques. Upon increasing the basic lanthana proportion in the acidic alumina support, the crystallinity of alumina and acidity of total support decline. Up to 15% Lanthana addition in support claims a low acid and rich basic surface including super basic sites (related to unidentate carbonates) which governed optimum catalytic performance 64% CH₄ conversion, 79% CO₂ conversion and H₂/CO ~ 1 up to 460-min in time on stream test. 20% lanthanum oxide loading led to inferior performance due to rapid loss of surface area, pore-volume, pore diameter, acidity and medium basic strength sites. Fine-tuning of acid-base lanthana-alumina support with dispersed Ni species are a means for understanding DRM.