Electrical and compositional properties of TaSi2 films

Tantalum silicide (TaSi₂) thin films were sputter deposited on p- and n-type silicon substrates using ultrapure TaSi₂ targets. The TaSi₂/Si samples were annealed in nitrogen or forming gas or oxygen containing steam at temperatures in the range of 400–900°C. The sheet resistances of TaSi₂/Si were measured by four-point probe before and after anneal. The structure of these films was investigated using x-ray diffraction (XRD) methods. It has been found that the sheet resistance decreases with the increase in annealing temperature and also with the increase in film thickness. X-ray diffraction patterns show changes in the morphological structure of the films. Oxidation characteristics of the film have been investigated in the temperature range of 400–900°C in oxygen containing steam ambient. The oxidation time ranged from 0.5 to 1.5 h. No oxide formation of the tantalum silicide films was observed in this investigation. This has been attributed to the high purity of TaSi₂ sputter targets used in the preparation of the films.     

Student–instructor communication: The role of email

We report on the use of email lists as a supplement to teaching. We argue that email lists can provide a valuable students–instructor communication channel and describe the process of setting up and managing such lists. A case study of email messages exchanged in an introductory operations research course is also included. The case illustrates how a ‘strategic’ use of email leads to a richer learning experience, by providing an extra medium for communication, and offers a valuable feedback database that can, among other things, be used to improve future editions of a course.     

Occurrence of multidrug resistance in Campylobacter from Ivorian poultry and analysis of bacterial response to acid shock

The level of antibiotic multiresistance of Campylobacter strains from chicken was evaluated and responses to the bactericidal effects of organic acids were analyzed. Strains (76) isolated from chicken were analyzed for resistance to antibiotics and acid shock. A high strain resistance to fluoroquinolones (ciprofloxacin and nalidixic acid) was observed, with cross resistance to both drugs in 41% of strains. A low resistance was observed for amoxicillin, erythromycin, and gentamicin. Campylobacter jejuni was the most resistant species. Antibacterial activities against multiresistant Campylobacter strains were observed using acetic, citric, and ascorbic acids at minimum bactericidal concentrations (MBC) ranging from 0.3 to 3 mg/mL. Acetic acid was the most efficient acid with the lowest MBC value. However, a contact time of 4 h was required for an efficient effect against Campylobacter contaminated chicken skin. Using organic acids in the poultry production chain can reduce propagation of antibiotic multiresistant strains of Campylobacter.     

Interpretation of the bowing phenomenon in Cd1−xZnxS alloy

A recent study about the energy band gap of the ternary Cd_1–x Zn _x S as a function of composition showed a new behavior. In fact, this behaviour is non-linear (bowing phenomenon) but differs from that of Ga_1–x AI _x As and several other ternary alloys in absence of monotony. Two ranges of zinc composition are proposed. This phenomenon is attributed to the significant effect of zinc on the electronic properties.     

Sampling of French local networks and applications

In this paper the authors describe a study in progress by which it is intended to represent all the French local telephone networks by just a small number of typical cases. The objectives are firstly, to gain a better knowledge of the existing network and secondly, to be able to compare equipment policies by simulating the evolution of the sample networks. The representative areas were chosen by original data analysis methods (principal component analysis followed by classification and choice of samples). Detailed data appertaining to the sample areas were then collected. They give examples of overall statistical results extrapolated at national level and discuss the corresponding applications. Lastly, they consider further developments of the study.     

Supplier selection and order lot sizing modeling: A review

With globalization and the emergence of the extended enterprise of interdependent organizations, there has been a steady increase in the outsourcing of parts and services. This has led firms to give more importance to the purchasing function and its associated decisions. One of those decisions which impacts all firms’ areas is the supplier selection. Since the 1950s, several works have addressed this decision by treating different aspects and instances. In this paper, we extend previous survey papers by presenting a literature review that covers the entire purchasing process, considers both parts and services outsourcing activities, and covers internet-based procurement environments such as electronic marketplaces auctions. In view of its complexity, we will focus especially on the final selection stage that consists of determining the best mixture of vendors and allocating orders among them so as to satisfy different purchasing requirements. In addition, we will concentrate mainly on works that employ operations research and computational models. Thereby, we will analyze and expose the main decision's features, and propose different classifications of the published models.