Solidification and crystallization properties of CaO-SiO2-Na2O based mold fluxes

Crystallization properties play an important role in keeping a smooth running of continuous casting process and high sur-face quality of cast strands. To reduce fluorine pollution in slag, a new type of CaO-SiO2-Na2O (CSN) based mold flux was studied. The solidification and crystallization properties, including crystallization temperature, crystallization ratio and solidification minera-graphy, were measured, which were compared with the CaO-SiO2-CaF2 (GF) mold flux. The results show that the crystallization performance is equal to the high fluoride mold powder and CSN can be used for peritectic steel grades sensitive to longitudinal cracking in continuous casting.     

The use of electrochemical noise methods (ENM) to study thick, high impedance coatings

Thick, high impedance organic coatings are those class of coatings used to provide corrosion protection to naval vessels, pipelines, gasoline storage tanks, and other large structures such as bridges and plant structures. These coatings, especially the newest generations now being used in practice, can provide exceptional protection and lifetime of performance such that properly and accurately assessing and differentiating among competing coatings is a very difficult task. The standard protocol of salt fog testing (ASTM B117), immersion testing, and outdoor exposure in a corrosive environment with subjective evaluation of a coating's performance durings and after testing, does not adequatcly rank and predict coating lifetimes for new coating systems, especially for the environmentally compliant coating systems such as powder coatings (especially the thick, fusion bonded epoxy (FBE) coatings used for pipelines), two component epoxy and urethane coatings and waterborne coatings. New, objective test methods are desperately needed by users and manufacturers of coatings. A relatively new electrochemical test procedure, electrochemical noise methods (ENM), as developed by Skerry and Eden, has been shown in our laboratory to be very successful in the ranking and prediction of relative coating performance. We have used the method successfully on naval ship coatings, several pipeline coatings and other related systems, and Skerry has used them successfully on industrial maintenance coatings. We have used these methods in conjunction with electrochemical impedance spectroscopy, d.c. resistance measurements and cyclic salt fog testing of the Prohesion^TM type. In our studies of pipeline coatings, we needed to investigate thermal effects because of their extended range of use temperature. In these studies, we have discovered that electrochemical methods can be used for an in situ measurement of the T_g of coatings in electrolyte immersion. Further, the ‘plasticizing’ effect of aqueous electrolyte absorption as well as its relative irreversibility has been shown. For all coatings studied, ENM provided useful, objective, numerical data which rapidly ranks coatings and provides useful information on the relative lifetime prediction of coatings which may provide up to 30 years of service.     

Diffraction contrast STEM of dislocations: imaging and simulations

The application of scanning transmission electron microscopy (STEM) to crystalline defect analysis has been extended to dislocations. The present contribution highlights the use of STEM on two oppositely signed sets of near-screw dislocations in hcp α-Ti with 6wt% Al in solid solution. In addition to common systematic row diffraction conditions, other configurations such as zone axis and 3g imaging are explored, and appear to be very useful not only for defect analysis, but for general defect observation. It is demonstrated that conventional TEM rules for diffraction contrast such as g·b and g·R are applicable in STEM. Experimental and computational micrographs of dislocations imaged in the aforementioned modes are presented.     

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.     

Internet addiction: Meta-synthesis of qualitative research for the decade 1996–2006

Internet addiction is “an individual’s inability to control their Internet use, which in turn leads to feelings of distress and functional impairment of daily activities” [Shapira, N., Lessig, M., Goldsmith, T., Szabo, S., Lazoritz, M., Gold, M. et al. (2003). Problematic Internet use: Proposed classification and diagnostic criteria. Depression and Anxiety, 17(4), 207–216]. Previous research in this field has offered inconclusive data on whether Internet addiction can be classified as a disorder. This study provides an in-depth and comprehensive analysis of internet addiction through a meta-synthesis of qualitative studies on excessive Internet use published during the period of 1996–2006. Several constructs pertaining to the domain of Internet addiction have been identified and a theoretical model of Internet addiction has been proposed.     

Molecular structures and conformational studies of triarylcyclopropyl and related nonsteroidal antiestrogens

Molecular structures and conformational characteristics of a series of 1,1-dichloro-2,2,3-triarylcyclopropanes (DTACs), which were reported previously to be distinctly antiestrogenic and inhibitors of the estrogen-receptor-positive MCF-7 human breast cancer cells in culture, are reported. In addition, structural and conformational features of the DTACs were compared to the first-known nonsteroidal antiestrogen, MER25, and the clinically useful antiestrogen Tamoxifen. The molecular structures of four DTAC compounds were determined by X-ray diffraction. Crystallographic structures show that the DTAC molecules have nearly the same relative conformation for the three aryl rings which is designated as a "nonpropeller" conformation in contrast to the observed "propeller" conformation for the three rings in all known triarylethylenes. Systematic conformational searches were performed to find the conformational preferences of DTACs, MER25, and Tamoxifen using idealized model compounds built from their respective crystal structure. Energy-minimization and conformational-search studies demonstrated that all DTAC molecules have a common, single global minimum energy conformer for their central core containing the dichlorotriarylcyclopropyl system, which is similar to that found in their crystal structures. Conformational search of MER25 showed that the molecule can assume a number of low-energy conformers of which two, one anti (A1) and one gauche (G1A), have about the same energy. The anti conformation is similar to the one observed in its crystal structure and resembles the estrogenic E-isomer of Tamoxifen, while the lowest energy gauche conformer of MER25 resembles more closely the antiestrogenic Z-isomer of Tamoxifen. NMR spectroscopic analysis of MER25 showed that the molecule exists predominantly in the anti conformation in solution. A comparative review of the structural features and bioactivities of Tamoxifen, DTACs, and MER25 provides a possible explanation for their low estrogen receptor binding affinity which is common to these compounds together with their antiestrogenic activity.     

An energy model of interframe interval effects in single-step apparent motion

A computational model was developed to explain the effects of an interframe interval (IFI) in single-step apparent motion experiments. In these experiments a stimulus appears in one position, disappears, and then reappears in a shifted position after a short or long IFI. If the luminance during the IFI matches the mean luminance of the stimulus frames, long IFIs result in perceived motion opposite the short-IFI conditions. Brighter or darker IFIs, however, do not support the reversed motion effect. The model possess the following defining characteristics: (1) a biphasic ("transient") channel whose signalled direction of motion reverses with changes of IFI duration; (2) a combined direction-opponent output which is the sum of directional responses developed in two channels--biphasic ("transient") and monophasic ("sustained"); (3) a signal/noise weighting of the contributions of the two channels to the final directional output of the system. Predictions of the model about the effects of IFI intensity and viewing eccentricity were tested and confirmed in two new psychophysical experiments. The interpretations of past studies which included a role for second-order motion mechanisms in explaining IFI duration effects were reexamined. Further empirical tests of the model were outlined.     

Design, fabrication and analysis of micromachined high sensitivity and 0% cross-axis sensitivity capacitive accelerometers

This paper presents the design and fabrication of three MEMS based capacitive accelerometers. The first design illustrates the achievement of an accelerometer with 0% cross-axis sensitivity and has been fabricated using PolyMUMPs, a multi-user surface-micromachining process. A unidirectional parallel plate configuration is utilized in this design to illustrate the achievement of 0% cross-axis sensitivity and an acceptable performance range. In addition, a method is introduced to improve the sensitivity of a capacitive sensor employing a transverse configuration based on the relationship of initial gaps setup in comb-finger arrangements. A design based on this technique and the PolyMUMPs fabrication process is illustrated which demonstrates a sensitivity value of 4.07 fF/μm, with a nonlinearity of 2.05% for a ±3 μm sensor operating range. The last design based on this method and the SOIMUMPs fabrication process exhibits a sensitivity of 3.45 pF/μm for ±1 μm operating range of the sensor.