Synthesis of analogues of ochratoxin A

Four analogues of ochratoxin A (OTA) differing for the aminoacidic moiety were synthesised using ochratoxin α (OTα) as the starting material. The condensation reaction between protected amino acids and OTα, carried out in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC???HCl) and N-hydroxybenzotriazole (HOBt) as coupling agents, followed by deprotection and PTLC purification afforded OTA alanine, leucine, serine and tryptophane analogues in satisfactory yields (33-47%, based on OTα).     

A finite differences MATLAB code for the numerical solution of second order singular perturbation problems

We show the main features of the MATLAB code HOFiD_UP for solving second order singular perturbation problems. The code is based on high order finite differences, in particular on the generalized upwind method. Within its simplicity, it uses order variation and continuation for solving any difficult nonlinear scalar problem. Several numerical tests on linear and nonlinear problems are considered. The best performances are reported on problems with perturbation parameters near the machine precision, where most of the codes for two-point BVPs fail.     

Determination of wine aroma compounds by dehydration followed by GC/MS

A new extraction method for the analysis of the volatile fraction of white and red wines has been developed and validated. A dehydration step with MgSO4 separated an aroma compounds-rich alcoholic-glycerine layer. Spiked samples showed good recoveries in the range between 75 and 120% with CVmax% of 17, except for 2-phenylethanol and y-butyrolactone for which recoveries in red wines were under 60%, and for monoethylsuccinate, where recoveries averaged 50 and 60% in white and red wines, respectively. Method repeatability and intermediate precision showed good CVmax% with minimum and maximum values between 7.7 and 24, and between 18.7 and 25.0, respectively. The average determination coefficients were greater than 0.99 with CVmax% of 13. The instrumental LOD and LOQ were, in all cases, under 0.05 mg/L, except for 2,3 butanediol (0.20 mg/L). Overall, the presence of wine matrix affected aroma compounds responses in GC/MS analysis. These observations indicate that the use of a matrix-matched calibration curve is mandatory to obtain reliable quantitative data.     

Polymer‐Bound Thiol Groups on Poly(2‐oxazoline)s

A new 2‐oxazoline monomer with a protected thiol group, 2‐[2‐(4‐methoxybenzylsulfanyl)ethyl]‐2‐oxazoline, MOB‐SOx , was synthesized from commercially available compounds. MOB‐SOx and 2‐ethyl‐2‐oxazoline (EtOx) were simultaneously polymerized yielding well defined copolymers with narrow molar mass distributions and target polymer chain length. The copolymerization was initiated by N‐methyl‐2‐methyl‐2‐oxazolinium triflate ( MeOxOTf ). After quantitative deprotection, poly(2‐oxazoline) with pendant thiol groups was obtained. The thiol groups were quantitatively added to the double bond of N‐phenyl‐acrylamide ( PhA ) and benzylmaleimide ( BzM ). Graft copolymers were obtained by reaction of those SH containing polymers with poly(2‐methyl‐2‐oxazoline)s bearing acrylamide ( PMeOx ₁₀ A ) and maleimide ( PMeOx ₁₀ M ) as terminal reactive groups.

     

Replication in Energy Markets: Use and Misuse of Chaos Tools

As pointed out by many researchers, replication plays a key role in the credibility of applied sciences and the confidence in all research findings. With regard, in particular, to energy finance and economics, replication papers are rare, probably because they are hampered by inaccessible data, but their aim is crucial. We consider two ways to avoid misleading results on the ostensible chaoticity of price series. The first one is represented by the proper mathematical definition of chaos and the related theoretical background, while the latter is represented by the hybrid approach that we propose here—i.e., consisting of considering the dynamical system underlying the price time series as a deterministic system with noise. We find that both chaotic and stochastic features coexist in the energy commodity markets, although the misuse of some tests in the established practice in the literature may say otherwise.     

Extended Fuzzy C-Means and Genetic Algorithms to Optimize Power Flow Management in Hybrid Electric Vehicles

The need for personal transportation must be harmonized by considering the impact of so huge number of vehicles on the environment. The adoption of hybrid electric vehicles can provide a sensible improvement from an environmental viewpoint, but at the same time makes more difficult the definition and implementation of the overall powertrain control mechanism. In fact, powertrain control problems are known to be very complex due to conflicting requirements, and this difficulty augments in case of hybrid electric vehicles. Most of the features of the future hybrid electric vehicles are enabled by a new energy flow management unit designed to split the instantaneous power demand between the internal combustion engine and the electric motor, ensuring both an efficient power supply and reduced emissions. Classic approaches that rely on static thresholds, optimized on a fixed drive cycle, cannot face the high dynamicity and unpredictability of real-life drive conditions. The need to actually control a real vehicle stimulates the research of innovative methodologies for the real-time identification of the operating points of each energy source. This paper is framed into this context: after a brief discussion about a non-conventional formalization of the energy flows problem based on a multiobjective function, a knowledge-based control system for splitting the vehicle's power demand between the engine and motor is presented. The proposed approach exploits a fuzzy clustering criterion that combined with a genetic algorithm, permits to achieve better results, both in terms of a reduced computational effort and an improved efficiency of the control system over various driving cycles. To validate the proposed approach, simulation tests and comparisons with other energy management strategies are discussed.     

Correlation Inequalities for Spin Glasses

We prove a correlation type inequality for spin systems with quenched symmetric random interactions. This gives monotonicity of the pressure with respect to the strength of the interaction for a class of spin glass models. Consequences include existence of the thermodynamic limit for the pressure and bounds on the surface pressure. We also describe other conjectured inequalities for such systems. Submitted: January 6, 2007. Accepted: May 10, 2007.