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The effects of slag content and polymer-binder ratio on the strength properties of autoclaved and combined wet! dry-cured SBR -modified concretes using ground granulated blast-furnace slag (GGBS) and styrene-butadiene rubber (SBR) latex are examined. As a result, the compressive and tensile strengths of the autoclaved and combined wet/dry-cured SBR-modified concretes using GGBS reach maxima at a slag content of 40%, and increase with increasing polymer-binder ratio. In particular, the autoclaved and combined wet/dry-cured SBR -modified concretes with a slag content of 40% and a polymer-binder ratio of 20% provide about three and two times higher tensile strengths than the same-cured unmodified concretes without GGBS, respectively. Such a high strength development is attributed to the improved bonds between cement hydrates and aggregates because of the incorporation of SBR latex. [ABSTRACT FROM AUTHOR]

Ferrocement (FC) is popularly used in many applications such as tanks, silos, and boats. For some special applications requiring su-perior properties, it is not advisable to use FC because of its limited mechanical properties and durability. This paper discusses the defor-mational behavior and durability of polymer-impregnated ferroce-ment (PIFC) in comparison with FC. PIFC and FC are prepared with different percentages of reinforcement and tested for flexure, direct tension, and impact resistance. It is concluded from the test results that the cracking composite stresses in flexure and direct tension of PIFC are improved 3 to 4 times over those of FC. The waterproof-ness, thermal resistance, and chemical resistance of polymer-impreg-nated matrix are also excellent in contrast with unmodified matrix. [ABSTRACT FROM AUTHOR]

The nonequilibrium radiation of shock fronts in air is experimentally investigated by means of the imaging spectroscopy technique. Shock velocity ranges from 9.7 to 11.6 km/s and initial pressure from 13.3 to 41.6 Pa. The spectral diagnostic system consists of an imaging spectrograph, a streak camera, a gated image-intensified CCD camera and a personal computer for data acquisition/processing. This spectral diagnostic system is capable of simultaneous wavelength-, intensity- and time-resolved spectroscopic measurements in the nanosecond order. The image processing of the streak images includes a combined smoothing/deconvolution process in the time direction to diminish experimental noise effects and the temporal broadening due to the streak camera entrance slit. Wavelength range is chosen to investigate the first negative band of $ N_{2}^{+}$ . “Large” and “slim” streak image types are observed. In the “large” streak images greater contribution from $N_{2}^{+}$ (1-)(1,0) behind the radiation peak is observed. Experimental data are compared with a streak image numerically simulated. The numerical simulation agrees better with the “slim” streak image. [ABSTRACT FROM AUTHOR]

The electronic structure of trimer acceptor-donor complexes in silicon Si clusters is studied using the ab initio discrete variational-Xα molecular-orbital (MO) method. The trimer complexes In[sub 2]D (D=phosphorus P, arsenic As, antimony Sb, or bismuth Bi) consist of two indium In acceptor elements and a centered donor element D from the group V elements. Calculations are performed under the assumption that the three atoms are arranged in the nearest neighbor substitutional trimer configuration. Results indicate that the trimer complexes act as shallower acceptors having smaller ionization activation energies than In acceptor. The potential of In[sub 2]D as an acceptor in Si is then discussed and In[sub 2]D is proposed as a promising acceptor for the formation of channels and source/drains in ultralarge scaled integration. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]