Antibacterial activity and chemical composition of 20 Eucalyptus species’ essential oils

The essential oils of twenty Eucalyptus species harvested from Zerniza and Souinet arboreta (North West and North of Tunisia), were screened for their antibacterial activities by the agar disc diffusion method. Eighteen major compounds, identified by GC and GC/MS, have been retained for the study of the chemical and biological activity variability. The main ones were 1,8-cineole followed by α-pinene, p-cymene, borneol, cryptone, spathulenol, viridiflorol and limonene. The chemical principal components analysis identified 10 chemotypes, however that of the inhibition zone diameter (izd) of growth bacteria separated 5 groups of Eucalyptus oils, characterised by their antibacterial inhibition ability. The most sensitive strain was the Gram positive Staphylococcus aureus with that of E. odorata oil (16.0 ± 1.0 mm izd), while the most resistant bacteria was Pseudomonas aeruginosa. Some correlation between the amount of 1,8-cineole, p-cymene, α-pinene, or of cryptone and the antibacterial activity were observed.     

A formal model for plastic human computer interfaces

The considerable and significant progress achieved in the design and development of new interaction devices between man and machine has enabled the emergence of various powerful and efficient input and/or output devices. Each of these new devices brings specific interaction modes.With the emergence of these devices, new interaction techniques and modes arise and new interaction capabilities are offered. New user interfaces need to be designed or former ones need to evolve. The design of so called plastic user interfaces contributes to handling such evolutions. The key requirement for the design of such a user interface is that the new obtained user interface shall be adapted to the application and have, at least, the same behavior as the previous (adapted) one. This paper proposes to address the problem of user interface evolution due to the introduction of new interaction devices and/or new interaction modes. More, precisely, we are interested by the study of the design process of a user interface resulting from the evolution of a former user interface due to the introduction of new devices and/or new interaction capabilities. We consider that interface behaviors are described by labelled transition systems and comparison between user interfaces is handled by an extended definition of the bi-simulation relationship to compare user interface behaviors when interaction modes are replaced by new ones.     

Segmented cell testing for cathode parameter investigation

The increasing quality and durability of solid oxide fuel cells (SOFCs) state-of-the-art materials renders the long-term testing of fuel cells difficult since considerably long equipment times are needed to obtain valuable results. Moreover, reproducibility issues are common due to the high sensitivity of the performance and degradation on the testing conditions. An original segmented cell configuration has been adopted in order to carry out four tests in parallel, thus decreasing the total experimental time and ensuring the same operating conditions for the four segments. The investigation has been performed on both anode-supported cells and symmetrical Lanthanum-Strontium Manganite-Yttria-stabilized Zirconia (LSM-YSZ) electrolyte-supported cells. In separate tests, the influence of variables like cathode thickness, current density and cathode composition on performance and degradation have been explored on anode-supported cells. Furthermore, the effect of chromium poisoning has been studied on electrolyte-supported symmetric cells by contacting one segment with a chromium-iron interconnect material. Long-term polarization of the segments is controlled with a multi-channel galvanostatic device designed in-house. Electrochemical characterization has been performed through electrochemical impedance spectroscopy (EIS) at different H₂ partial pressures, temperatures and bias current, effectively demonstrating the direct impact of each studied variable on the cell performance and degradation behavior. Segmented cell testing has been proven to be an effective strategy to achieve better reproducibility for SOFC measurements since it avoids the inevitable fluctuations found in a series of successively run tests. Moreover, simultaneous testing increased n-fold the data output per experiment, implying a considerable economy of time.     

Stress analysis of steel beams strengthened with a bonded hygrothermal aged composite plate

In this paper, the problem of interfacial stresses in steel beams strengthened with bonded hygrothermal aged composite laminates is analyzed using linear elastic theory. The analysis is based on the deformation compatibility approach developed by Tounsi (Int. J. Solids Struct. 43:4154–4174, 2006) where both the shear and normal stresses are assumed to be invariant across the adhesive layer thickness. The adopted model takes into account the adherend shear deformations by assuming a linear shear stress through the depth of the steel beam. This solution is intended for application to beams made of all kinds of materials bonded with a thin composite plate. For steel I-beam section, a geometrical coefficient ξ is determined to show the effect of the adherend shear deformations. This research is helpful for the understanding on mechanical behaviour of the interface and design of such structures.     

Suppression of self-pulsing in Er-doped fibre lasers with electronic control

Abstract

We propose a new method to suppress the self-pulsing behaviour occurring in heavily-doped erbium-fibre lasers. The method consists of an electronic feedback on the pumping laser. It is theoretically demonstrated that this simple method efficiently stabilizes the output of the laser without changing the laser threshold and the laser efficiency.     

Attempted suicide and menstrual cycle. An epidemiologic study

Acute-phase reactant proteins have been considered in searching for new biochemical tumor markers useful at initial diagnosis, staging and monitoring of colorectal cancer. In this study, we aimed to determine the role of acute-phase reactant proteins in combination with carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA 19-9) at the preoperative staging of colorectal cancer. In 22 patients with cancers of the colon and rectum and in 9 control patients without cancer, the serum levels of CEA, CA 19-9, C-reactive protein (CRP), alpha 1-antitrypsin (AAT) and alpha 1-acid glycoprotein (AAG) were measured. While statistical analysis did not show significant correlations between serum CEA, AAT and CRP levels with the stage of disease, the significant correlations between serum CA 19-9 and AAG concentrations with the extent of cancer were detected (p < or = 0.0197 and p < or = 0.0378, respectively). Multivariate discriminant analysis gave a final prognostic model that included serum CA 19-9 and AAG levels with a significance of p < or = 0.0089. The Linear regression analysis also gave a form of (Stage = 0.04667 + 0.0077 x CA 19-9 + 0.0068 x - AAG) for staging. We considered that the serum AAG levels, in combination with serum CA 19-9 concentrations may have an important role in the preoperative staging of colorectal cancer.     

Multi‐hour design of survivable classical IP networks

Most of Internet intra‐domain routing protocols (OSPF, RIP, and IS–IS) are based on shortest path routing. The path length is defined as the sum of metrics associated with the path links. These metrics are often managed by the network administrator. In this context, the design of an Internet backbone network consists in dimensioning the network (routers and transmission links) and establishing the metric. Many requirements have to be satisfied. First, Internet traffic is not static as significant variations can be observed during the day. Second, many failures can occur (cable cuts, hardware failures, software failures, etc.). In this paper, we present algorithms (meta‐heuristics and greedy heuristic) to design Internet backbone networks, taking into account the multi‐hour behaviour of traffic and some survivability requirements. Many multi‐hour and protection strategies are studied and numerically compared in this paper. Our algorithms can be extended to integrate other quality of service constraints. Copyright © 2002 John Wiley & Sons, Ltd.     

Complex fluid flow in annular space under the effects of mixed convection and rotating wall of the outer enclosure

This study aims to investigate the roles of pertinent parameters on the mixed convection of complex liquids in annular devices. The investigated area consists of two circular cylinders with fixed and heat walls. Both cylinders are enclosed within a circular room with a cold wall and rotate regularly. The zone between the inner obstacles and the outer space contains complex power-law fluids. This investigation is numerically achieved by using the package ANSYS-CFX, which is based on the finite-volume method. The parameters studied in this study are the arrangement and size of inner tubes (d/D), the rotational speed of outer space, the rheological nature of fluids (n), and the relative concentration of thermal buoyancy force. These pertinent parameters were quantitatively expressed for the following values: d/D (= 0.1, 0.25, and 0.45); Reynolds number (Re = 1 to 20); flow behavior index (n = 0.6, 1 and 1.6); Richardson number (Ri = 0 to 100), respectively. It was found that increasing the thermal buoyancy value and the rotational speed of the outer container increases the rate of heat transfer of the cylinders in the vertical and horizontal arrangement. For example, for shear-thinning fluid (n = 0.6), raising the value of Ri from 0 to 100 increases Nu by 59.67% for d/D = 0.1. Also, the arrangement of the two cylinders differently affects the dynamic behavior of the fluid within the studied space.     

Single-machine multi-agent scheduling problems with a global objective function

In this paper, we consider the problem of scheduling independent jobs when several agents compete to perform their jobs on a common single processing machine. Each agent wants to minimise its cost function, which depends exclusively on its jobs and we assume that a global cost function concerning the whole set of jobs has to be minimised. This cost function may correspond to the global performance of the workshop or to the global objective of the company, independent of the objectives of the agents. Classical regular objective functions are considered and both the ε-constraint and a linear combination of criteria are used for finding compromise solutions. This new multi-agent scheduling problem is introduced into the literature and simple reductions with multicriteria scheduling and multi-agent scheduling problems are established. In addition, the complexity results of several problems are proposed and a dynamic programming algorithm is given.