Serotonin receptor 1A knockout: an animal model of anxiety-related disorder

To investigate the contribution of individual serotonin (5-hydroxytryptamine; 5-HT) receptors to mood control, we have used homologous recombination to generate mice lacking specific serotonergic receptor subtypes. In the present report, we demonstrate that mice without 5-HT1A receptors display decreased exploratory activity and increased fear of aversive environments (open or elevated spaces). 5-HT1A knockout mice also exhibited a decreased immobility in the forced swim test, an effect commonly associated with antidepressant treatment. Although 5-HT1A receptors are involved in controlling the activity of serotonergic neurons, 5-HT1A knockout mice had normal levels of 5-HT and 5-hydroxyindoleacetic acid, possibly because of an up-regulation of 5-HT1B autoreceptors. Heterozygote 5-HT1A mutants expressed approximately one-half of wild-type receptor density and displayed intermediate phenotypes in most behavioral tests. These results demonstrate that 5-HT1A receptors are involved in the modulation of exploratory and fear-related behaviors and suggest that reductions in 5-HT1A receptor density due to genetic defects or environmental stressors might result in heightened anxiety.     

Effect of transverse cracks on the elastic properties of high temperature angle-ply laminated composites

The development of transverse cracks can be detrimental to the stiffness and dimensional stability of composite laminates. In this investigation, a modified shear lag analysis, taking into account the concept of stress perturbation function, is employed to evaluate the effect of transverse cracks on the stiffness reduction in high temperature angle-ply laminated composites. The results present well the effect of high temperature and the fibre orientation of the outer layers on the degradation of mechanical properties of the angle-ply polymer composite laminates.     

Analytical prediction of eddy-current loss in modular tubular permanent-magnet machines

The paper describes an analytical technique for predicting the eddy-current loss in the moving armature of a tubular permanent magnet machine. This loss component is usually neglected in conventional tubular permanent magnet machines since high-order time harmonics in the stator current waveform and space harmonics in the winding magnetomotive force (MMF) distribution are generally considered to be insignificant. However, a relatively new topology of tubular permanent magnet machine, sometimes referred to as "modular", has emerged in which the fundamental component of the stator MMF has fewer poles than that of the permanent-magnet armature, the thrust force being developed by the interaction between a higher order MMF harmonic and the permanent magnet field. Thus, the presence of lower and higher order space harmonics in the winding MMF distribution of a modular machine may gives rise to a significant eddy-current loss in the moving-magnet armature. An analytical model is developed to predict the eddy currents which are induced in the magnets, as well as in any electrically conducting supporting tube which may be employed, and to quantify the effectiveness of axially segmenting the magnets in reducing the eddy-current loss. The validity of the developed model, which is also applicable to conventional designs of tubular permanent-magnet machine, is verified by time-stepped transient finite-element analysis (FEA).     

Localization and function of five glutamate transporters cloned from the salamander retina

Glutamate is the major excitatory neurotransmitter in the vertebrate retina. Native glutamate transporters have been well characterized in several retinal neurons, particularly from the salamander retina. We have cloned five distinct glutamate transporters from the salamander retina and examined their localization and functional properties: sEAAT1, sEEAAT2A, sEAAT2B, sEAAT5A and sEAAT5B. sEAAT1 is a homologue of the glutamate transporter EAAT1 (GLAST), sEAAT2A and sEAAT2B are homologues of EAAT2 (GLT-1) and sEAAT5A and sEAAT5B are homologues of the recently cloned human retinal glutamate transporter EAAT5. Localization was determined by immunocytochemical techniques using antibodies directed at portions of the highly divergent carboxy terminal. Glutamate transporters were found in glial, photoreceptor, bipolar, amacrine and ganglion cells. The pharmacology and ionic dependence were determined by two-electrode voltage clamp recordings from Xenopus laevis oocytes which had previously been injected with one of the glutamate transporter mRNAs. Each of the transporters behaved in a manner consistent with a glutamate transporter and there were some distinguishing characteristics which make it possible to link the function in native cells with the behavior of the cloned transporters in this study.     

Microscopic structural evolution in terms of porosity in high-Tc superconductors

The low critical current densities of high-Tc superconductors materials can be related to the microstructural imperfections such as pores and microcracks, which reduce the effective current carrying cross section. The present work examines the characterisation of the state of microstructure and its evolution during thermal treatment of Bi₂Sr₂Ca₁Cu₂O₈. The dilatometric analysis was used to study the shrinkage mechanism during sintering. The microstructure of the sintered samples was characterised in terms of pores distribution and apparent density. Open porosity was measured by mercury porosimeter. In order to compare the results, ultrasonic characterisation such as the longitudinal and transverse wave velocities in the ceramic was carried out. From an ultrasonic point of view, these microstructural features act as inhomogeneities and the ultrasonic parameters will depend on the geometrical arrangement of microstructure (pores have an effect both on Young’s modulus and attenuation).     

Control by virtual gauge of skew surfaces for correction process

The automation of production has been considerably developed in recent years in all its phases from design and manufacturing to control. The design and manufacture of free form surfaces are a current practice in the industry; thus, the conformity problem of complex geometry parts is felt more and more. The co-ordinate measurement machine (CMM) has largely reduced the acquisition and processing time in the take up measurement operation, which explains the wide use of the CMM in the mechanical industry over the last decade. The modelling and controlling procedure proposed within this paper enables correction of complex surfaces during the parts manufacturing process. The method is based on real surfaces modeled by finite elements starting from cloud points obtained by a digitalizing procedure in the co-ordinate measurement machine. The procedure was applied on a tooth gear which equips the gear box manufactured in the Algeria Engines and Tractors Factory. A comparison between the real and ideal model has been established showing the defects of form in order to correct the grinding process. This comparison is carried out by associating a surface of perfect geometry to a group of palpated dots. The selected criterion of optimisation is the least squares method.     

Characterization of Emissions from Liquid Fuel and Propane Open Burns

The effect of accidental fires are simulated to understand the response of items such as vehicles, fuel tanks, and military ordnance and to remediate the effects through re-design of the items or changes in operational procedures. The comparative combustion emissions of using jet propellant (JP-5) liquid fuel pools or a propane manifold grid to simulate the effects of accidental fires was investigated. A helium-filled tethered aerostat was used to maneuver an instrument package into the open fire plumes to measure CO, CO₂, fine particulate matter (PM_2.5), polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and elemental/organic/total carbon (EC/OC/TC). The results showed that all emissions except CO₂ were significantly higher from JP-5 burns than from propane. The major portion of the PM mass from fires of both fuels was less than 1 µm in diameter and differed in carbon content. The PM_2.5 emission factor from JP-5 burns (129 ± 23 g/kg Fuel_c) was approximately 150 times higher than the PM_2.5 emission factor from propane burns (0.89 ± 0.21 g/kg Fuel_c). The PAH emissions as well as some VOCs were more than one hundred times higher for the JP-5 burns than the propane burns. Using the propane test method to study flammability responses, the environmental impact of PM_2.5, PAHs, and VOCs would be reduced by 2300, 700, and 100 times per test, respectively.     

Effect of partial replacement of potassium lactate and sodium diacetate by natural green tea and grape seed extracts and postpackaging thermal treatment on the growth of Listeria monocytogenes in hotdog model system

Low‐ (5%) and high‐fat (20%) chicken and turkey hotdogs were formulated in three groups: no antimicrobials (control), chemical preservatives (potassium lactate and sodium diacetate) alone and partial replacement of chemical preservatives by green tea (GTE) and grape seed extracts (GSE), surface inoculated (c. 10³ CFU g^?1) with Listeria monocytogenes, treated with or without heat treatment (65 °C for 104 s) to determine the growth of L. monocytogenes until spoilage (28 days). Maximum growth inhibitions (c. 2.0 CFU g^?1) were observed in the treatments having chemical preservatives and plant extracts regardless of the meat and fat type. Furthermore, plant extracts along with chemical preservatives demonstrated additional inhibitory effect on the growth of L. monocytogenes survivors in chicken hotdog samples followed by postpackaging heat treatment. Results demonstrated that natural GTE and GSE can partially replace the chemical preservatives and further enhance the antilisterial activities when combined with heat treatment.     

Polymer powders mixing part I: Mixing characterization in rotating cylinders

In the production of rotomolded parts, the distribution of particle sizes in the form of polymer powder is highly important to produce parts of good quality. In the case of polymer blends, the particle size distribution becomes even more important to assure that good mixing occurs before the polymer melts. In this work, the mixing of free flowing polymer powders in a horizontal rotating cylinder has been studied. Special attention is given to the initial moments of mixing and the transition from a standstill to a fully developed rolling regime. The parameters studied include Froude number (rotational speed), cylinder loading, relative powder composition and particle sizes. For the first time, mixing dynamics are quantified using two image analyzes: grey-level co-occurrence matrix (GLCM) and Threshold methods. Using the experimental data, a model is proposed to follow the mixing dynamics and to determine the equilibrium time. The results also indicate that the Froude number is not enough to characterize the flow regime and the filling ratio must be accounted for.