Interaction between medetomidine and alkyd resins: NMR and FTIR investigation of antifouling marine paint model systems

The synthesis and optimization of novel bioactive components is key to the development of antifouling marine coatings. It was recently demonstrated that medetomidine (MM) has perfect antibarnacle behavior along with good ecological properties. To investigate the applicability of MM in self‐polishing marine paints, a large set of mixtures of MM with two commercial alkyd resins (ARs) was prepared. The nature and strength of the intermolecular interaction as a function of composition in both the liquid and solid states were studied using NMR and FTIR techniques, respectively. It was found that at low concentrations MM molecules were coordinated to alkyd resin chains by hydrogen bonding. This interaction had a multidentate character (i.e., one molecule of MM interacted with several ? COOH species of ARs) that resulted in stronger bonding between the two compounds. However, at higher MM concentrations an ionic association between the two compounds began, which at a large MM content resulted in microphase separation. It was noted that the strong interaction between medetomidine and the alkyd resins investigated was a positive factor for the application of these compounds in self‐polishing marine paints. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 2006     

Multibody modelling of N DOF robot arm assigned to milling manufacturing. Dynamic analysis and position errors evaluation

Nowadays, with the large use of robot manipulators in the most different fields of industrial production, two main aims must be commonly reached: robot dynamic behavior improvement and end-effector position errors reduction. For a N DOF robot arm, in case of specific applications such as milling manufacturing, one of the main source of end-effector position errors can be identified with joint compliances. This aspect, well known in literature, has been confirmed by experimental tests and measurements carried out on a specific robot assigned to non-standard milling manufacturing of marble objects (sculptures realization). To approach and analyze this issue the authors chose the multibody simulation environment. Hence, the authors developed a parametric modelling procedure that, by determining the robot characteristics through CAD model and technical data sheet investigation, provides reliable multibody dynamic models of generic N DOF robot arms. In this modelling approach the robot geometry construction is based on a standard strategy typical of this research field (i.e. Denavit-Hartenberg, Veitschegger-Wu). The developed procedure enables to obtain robot representation at various complexity levels according to the number of modelled robot components and actuation typology (Motion laws defined both in displacement or applied torque). Eventually, for a specific test case, the authors were able to correctly simulate the robot dynamic behavior, as it was demonstrated by numerical/experimental comparison. In this way the influence of the joint compliance behavior and actuator rotational inertia effects on end-effector position accuracy was analyzed.     

Influence of nature, concentration and pH of buffer acid-base system on rate determining step of the electrochemiluminescence of Ru(bpy)3 with tertiary aliphatic amines

The electrogenerated chemiluminescence (ECL) of Ru(bpy)₃²⁺ (bpy = 2,2′-bipyridyl) with tertiary aliphatic amines as co-reactants, was theoretically and experimentally studied as a function of the pre-equilibria involved in the ammonium proton lost and in relation to the nature of the rate determining step. Transient potential steps were used with a 3-mm glassy carbon disk electrode or carbon fiber ultramicroelectrodes array to investigate emission behavior in a variety of aqueous solution types, containing phosphate, tartrate and phthalate acid-base systems at differing pH values. The emission of Ru(bpy)₃²⁺ resulting from the reaction with n-tripropylamine (TPrA), tri-isobutylamine (TisoBuA), n-tributylamine (TBuA), methyl-di-n-propylamine (MeDPrA) and triethylamine (TEtA) in varying acid-base media was interpreted on the basis of the quoted pre-equilibria, ammonium pK_a being known. The nature of the rate determining steps changes depending on pH. Above pH ≈ 5 the amine neutral radical formation is the rate determining step and, is independent of pH with rate constant close to 10³ s⁻¹; below pH ≈ 5 the rate determining step becomes the deprotonation of the ammonium ion, operated by different bases present in solution. Different amines in the same acid-base system showed analogous ECL behavior, conditioned by the chosen acid base system. A single amine in different acid-base systems showed different kinetic behaviors, due to the dissociation constants of the chosen buffers. The concentration of the acid-base system also played an important role and influenced emission intensity and shape. ECL emission were simulated by finite difference methods, implementing a previously proposed mechanism by including the relevant pre-equilibria. Simulation may also give estimates of the pK_a values of the ammonium ions. An ion pair formation between R₃N⁺ and the mostly charged species present in solution is hypothesized to explain the contradictory experimental results concerning the reaction mechanism of the proton lost of the radical cation.     

Deuterium permeation behavior of erbium oxide coating on austenitic,ferritic, and ferritic/martensitic steels

Tritium permeation barrier is required in fusion blanket for reduction of loss of fuel and health hazard. In this study, deuterium permeation experiments have been performed on four kinds of steels and erbium oxide coatings fabricated by a filtered arc deposition method. The permeation flux of uncoated samples shows diffusion-limited regime in the temperature range 573–723 K and the permeability is corresponding to literature data. The coated samples deposited at room temperature have been tested at 773 K. It is found that the coatings suppress the deuterium permeation to a close level in spite of different types of steel substrates. In addition, the exponent of the driving pressure slightly changes compared to the uncoated sample. However, the permeation regime is still near diffusion limited.     

Etude de la conduction ionique de verres a base de ZrF4

The electrical and dielectric properties of new ZrF₄ based glasses have been studied in the frequency and temperature ranges 5Hz-500kHz and 130–280°C. Transport number measurements following Tubant's method showed that the glasses investigated are F^? conductors. The conductivities and activation energies for conduction are about 10^?6(Ωcm)^?1 at 200°C and 18 kcal.mole^?1 respectively. Preliminary interpretation of the change of conductivity with composition is given.     

The effect of the descent technique and truck cabin layout on the landing impact forces

The majority of injuries to truckers are caused by falls during the descent from the cab of the truck. Several studies have shown that the techniques used to descend from the truck and the layout of the truck's cabin are the principal cause of injury. The goal of the present study was to measure the effects of the descent techniques used by the trucker and the layout of the truck's cabin on the impact forces absorbed by the lower limbs and the back. Kinematic data, obtained with the aid of a video camera, were combined with the force platform data to allow for calculation of the lower limb and L₅–S₁ torques as well as L₅–S₁ compressive forces. The trucker descended from two different conventional tractor cabin layouts. Each trucker descended from cabin using either “facing the truck” (FT) or “back to the truck” (BT) techniques. The results demonstrate that the BT technique produces greater ground impact forces than the FT technique, particularly when the truck does not have a handrail. The BT technique also causes an increase in the compressive forces exerted on the back. In conclusion, the use of the FT technique along with the aids (i.e., handrails and all the steps) help lower the landing impact forces as well as the lumbosacral compressive forces.     

Two-handed performance of a rhythmical Fitts task by individuals and dyads.

The authors investigated 4 variants of a reciprocal Fitts task in which the pointer was moved to a stationary target, the target was moved to a stationary pointer, or both the pointer and the target were moved to each other bimanually; the bimanual task was carried out either by a single person or by a dyad. Fitts's law held in all 4 conditions, with only minor parametric changes. The kinematic organization varied with task difficulty but remained invariant in task space (i.e., in the mutual frame of reference of the pointer-target system) whatever the pointing condition. In the bimanual conditions, the 2 effectors were coordinated in antiphase with compensatory variability. The authors suggest that the observed chronometric and kinematic patterns emerge from an interplay between simple harmonic motion and the stabilizing influence of the informational flow generated by the closing of the gap between the pointer and the target interval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Power increase and metallurgical effects during arc heating of liquid steel due to the addition of molecular gases

Molecular gases were laterally injected into the gas atmosphere of a pilot furnace containing 200 kg of steel melt and heated by two AC argon plasma arcs. The power increase in the arcs obtained by the injection was 12 % for 20 % N₂, 70 % for 20 % CO₂, 32 % for 3 % CH₄, and 62 % for 3 % C₃H₈. Mixtures of CO₂ and hydrocarbons were also tested. CO₂ acted as an oxidizing agent for steel components with oxygen transfer efficiencies of 28 % in the case of slag-free steel melts and of 10 % in the presence of slag, while the addition of CH₄ did not cause any noticeable carbon transfer to the melt.     

Analysis of Fowler–Nordheim injection in NO nitrided gate oxide grown on n-type 4H–SiC

Fowler–Nordheim injection in NO nitrided gate oxides, grown on n-type 4H–SiC, has been investigated at room temperature and 300°C. The results show that NO increases the electron injection barrier height to a value which is very close to the theoretical value at room temperature. Excessive temperature dependence of the electron injection barrier height is also significantly reduced by the nitridation.