Effects of the sintering atmosphere on Nb-based dielectrics

The effects of a forming atmosphere on the stability, the sintering and the dielectric properties of Ba₅Nb₄O₁₅, BaNb₂O₆, ZnNb₂O₆ and Zn₃Nb₂O₈ ceramics were investigated, because of the primary importance of the sintering atmosphere in relation to copper sintering. These Nb-based materials were sintered in air and in Ar/H₂10%. Zn-containing samples are very sensitive to the reductive atmosphere. ZnO volatilises at 800–850 °C and the resulting compound does not exhibit the expected properties. BaNb₂O₆ and Ba₅Nb₄O₁₅ are more stable in term of relative weight loss. Nevertheless, the phase analysis reveals a modification of the BaNb₂O₆ phase, what induces the degradation of the dielectric property stability versus temperature. The properties of Ba₅Nb₄O₁₅ are not modified by a sintering in reductive atmosphere. A relative permittivity of 38.8, a permittivity temperature coefficient of −150 ppm °C⁻¹ and an insulating resistivity of 10^10.9 Ω cm were obtained for this latter.     

Structural control in radical polymerization with 1,1 diphenylethylene: 2. Behavior of MMA-DPE copolymer in radical polymerization

Copolymers of 1,1-diphenylethylene (DPE) behave in a very special way in radical polymerization. Particularly, the behavior of MMA-DPE copolymers in radical polymerization is investigated. The results reveal that the semiquinoid structure of the precursor polymer identified in a previous contribution is activated by the attack of free radicals and thus, in a second stage polymerization with a second monomer, block copolymers are formed. The block copolymer yield depends strongly on the ratio between the amount of DPE-containing precursor polymer and the initiator and monomer concentration used in the second stage. The mechanism proposed is able to explain at least qualitatively all experimental results including the restriction of this mode of control of radical polymerization to the formation of diblock copolymers only.     

The magnetic-distortion probe: velocimetry in conducting fluids

A new type of velocimeter, capable of local velocity measurements in conducting fluids, is introduced. The principle of the "magnetic-distortion probe" is based on the measurement of the induced magnetic field by the flow of a conducting fluid in the vicinity of a localized magnetic field. The new velocimeter has no moving parts, and can be enclosed in a sealed cap, easing the implementation in harsh environments, such as liquid metals. The proposed method allows one to probe both the continuous part and fluctuations of the velocity, the temporal and spatial resolution being linked to the actual geometric configuration of the probe. A prototype probe has been tested in a gallinstan pipe flow and in a fully turbulent flow of liquid gallium generated by the counter rotation of two coaxial impellers in a cylinder. The signals have been compared to a reference potential probe and show very good agreement both for time-averaged velocities and turbulent fluctuations. The prototype is shown to detect motion from a few cm s(-1) to a few m s(-1). Moreover, the use of the magnetic-distortion probe with large-scale applied magnetic field is discussed.     

Reviews

MARK FRESKO CONSULTANCY. Sources of digital information. British Library R&D Report 6102. London: British Library Research and Development Department, 1994. No ISBN given. No price indicated. 260 pp.

CHRIS CLARE and GORDON STUTELEY. Information systems — strategy to design. London: Chapman and Hall, 1995. ISBN 0 412 576708. £16.99.

POPE, IVAN. Internet UK. Hemel Hempstead: Prentice Hall International, 294 pp. ISBN 013 190950, £19.95. SCHOFIELD, SUE. UK Internet book. Wokingham: Addison‐Wesley, 301 pp. ISBN 0201 42766 4, £19.95.

RIMMER, STEVE. Planet Internet. New York: Windcrest, 1995. ISBN 0 8306 24724. £22.95 (pbk).

JILL H. ELLSWORTH and MATTHEW V. ELLSWORTH. The Internet business book. London: John Wiley & Sons, 1994. $22.95, 376pp. ISBN 0 471058092.

JOHN S. QUARTERMAN and SMOOT CARL‐MITCHELL. The e‐mail companion: communicate effectively via the Internet and other global networks. Addison‐Wesley, 1994. 318 pp. ISBN 0 201 40658 6. $19.95.

McCLURE, C.R., MOEN, W.E. and RYAN, J. Libraries and the Internet/NREN: perspectives, issues and challenges. London: Mecklermedia 1994. $35.00. ISBN 0 89736 824 7. McCLURE, C.R., BERTOT, J.C., and ZWEIZIG, D.L. Public libraries and the Internet: study results, policy issues and recommendations. Washington: National Commission on Libraries and Information Science, 1994. No price or ISBN given.

FRANCES BLOMELEY. Networks and network services: a user's guide. Immediate Publishing, 1994. ISBN 1–89831–00–03. 246 pp. £14.95.

NEIL SMITH (ed) ibraries, networks and Europe: a European networking study. British Library Research and Development Department, 1994. (LIR Series 101) 91 pp. ISBN 0 7123 3295 2. £25. (Distributed by Turpin Distribution Services Ltd, Blackhorse Road, Letchworth, Herts. SG6 1HN).

ALAN BRYANT. Creating successful bulletin board systems. Addison‐Wesley, 1994. ISBN 0–201–62668–3. $39.95.

Directory of electronic journals, newsletters and academic discussion lists. 4th ed. Compiled by Lisabeth A. King and Diane Kovacs, edited by Ann Okerson. Washington, DC: Association of Research Libraries, 1994. 575 pp. ISSN 1057–1337. $54 (paperback), $33 (ARL members).

THE BRITISH LIBRARY and ELECTRONIC PUBLISHING SERVICES LTD. Electronic publishing practice in the UK: LIR Report 95. University Press, Cambridge, 1994. 185 pp. ISBN 0 7123 3280 4. £30.00. (Distributed by Turpin Distribution Services, Blackhorse Road, Letchworth S96 1HN).

INTERNET WORLD'S On Internet 94: an international guide to electronic journals, newsletters, texts, discussion lists, and other resources on the Internet. edited by Tony Abbott with a Preface by Daniel P. Dem. Westport, London: Mecklermedia, 1994. £29.50 $45.00. ISBN 0–88736–929–4.

S. BANG. The Internet unleashed. Indianapolis: SAMS Publishing, 1994. $44.95. ISBN 0 672 30466 X.

GAIL K. DICKINSON, Selection and evaluation of electronic resources. Libraries Unlimited, 1994. ISBN 1 56308 098 2. £22.50.     

Multi-behavior agent model for planning in supply chains: An application to the lumber industry

Recent economic and international threats to western industries have encouraged companies to increase their performance in all ways possible. Many look to deal quickly with disturbances, reduce inventory, and exchange information promptly throughout the supply chain. In other words they want to become more agile. To reach this objective it is critical for planning systems to present planning strategies adapted to the different contexts, to attain better performances. Due to consolidation, the development of integrated supply chains and the use of inter-organizational information systems have increased business interdependencies and in turn the need for increased collaboration to deal with disturbance in a synchronized way. Thus, agility and synchronization in supply chains are critical to maintain overall performance. In order to develop tools to increase the agility of the supply chain and to promote the collaborative management of such disturbances, agent-based technology takes advantage of the ability of agents to make autonomous decisions in a distributed network through the use of advanced collaboration mechanisms. Moreover, because of the highly instable and dynamic environment of today's supply chains, planning agents must handle multiple problem solving approaches. This paper proposes a Multi-behavior planning agent model using different planning strategies when decisions are supported by a distributed planning system. The implementation of this solution is realized through the FOR@C experimental agent-based platform, dedicated to supply chain planning for the lumber industry.     

Engineering of protein epitopes: a single deletion in a snake toxin generates full binding capacity to a previously unrecognized antibody

Structural features associated with the ability of a monoclonalantibody (mAb) to discriminate between protein variants areidentified and engineered. The variants are the curaremimetictoxin from Naja nigricollis and erabutoxin a or b from Laticaudasemifasciata which differ from each other by 16 substitutionsand one insertion. The neutralizing mAb M1 recognizes with highaffinity a topographical epitope on the surface of toxin , butfails to recognize the erabutoxins although they possess mostof the residues forming the presumed epitope. Examinations ofthe toxin and erabutoxin 3-D structures and molecular dynamicssimulations reveal several differences between the variants.In particular, the region involving the ß-turn 17–24is organized differently. Analysis of the differences foundin this region suggests that the insertion (or deletion) atposition 18 of the variant amino add sequences is particularlyimportant in determining the differential cross-reactivity.To test this proposal, residue 18 was deleted in one erabutoxinusing sitedirected mutagenesis, and the biological propertiesof the resulting mutant were examined. We found that full antigenicitywas restored in the previously unrecognized variant. The implicationsof this finding are discussed.     

Biodegradable Microparticles for Simultaneous Detection of Counterfeit and Deteriorated Edible Products

In an era of globalized trade relations where food and pharmaceutical products cross borders effortlessly, consumers face counterfeit and deteriorated products at elevated rates. This paper presents multifunctional, biodegradable hydrogel microparticles that can provide information on the authenticity and the potential deterioration of the tagged food or pharmaceutical formulations. These microparticles integrate spatially patterned authenticity code with two sensors—the first one detects possible presence of pathogenic microbes through monitoring pH while the second one identifies products stored above optimal temperatures via optical monitoring of the microparticle degradation. Particles are synthesized from a biocompatible polymer and a photoinitiator, dextran modified with 2‐hydroxyethylmethacrylate and riboflavin, respectively, using a continuous, high throughput method stop‐flow lithography. The proposed synthesis approach also enables crosslinking with visible light bringing about additional flexibility to flow lithography. Model liquid and solid food and pharmaceutical products are successfully labeled with microparticles and the functionality of the sensors in aqueous solutions is demonstrated.     

State feedback design for input-saturating quadratic systems

This paper proposes a method to design stabilizing state feedback control laws for nonlinear quadratic systems subject to input saturation. Based on a quadratic Lyapunov function, a modified sector condition and a particular representation for the quadratic terms, synthesis conditions in a “quasi”-LMI form are stated in a regional (local) context. An LMI-based optimization problem is then derived for computing the state feedback gains maximizing the estimate of the stability region of the closed-loop system.     

Variable neighborhood search for the dial-a-ride problem

In dial-a-ride problems passengers have to be transported between pre-specified pickup and delivery locations under user inconvenience considerations. The problem variant considered in this paper aims at minimizing total routing costs while respecting maximum route duration limits, time windows, and maximum user ride time limits. We propose a competitive variable neighborhood search-based heuristic, using three classes of neighborhoods. The first neighborhood class uses simple swap operations tailored to the dial-a-ride problem; the second neighborhood class is based on the ejection chain idea; and the third neighborhood class exploits the existence of arcs where the vehicle load is zero, giving rise to natural sequences of requests. We report new best results for 16 out of 20 benchmark instances.