The Effect of Ionic Surfactant Adsorption on the Rheology of Ceramic Glaze Suspensions

The rheological behavior of ceramic glaze suspensions containing limestone, quartz, feldspar, and kaolin, has been improved by the addition of either a cationic (cetylpyridinium chloride, CPC) or an anionic (sodium dodecylbenzenesulfonate, SDBS) surfactant. Additional stability and lower viscosity can result from either electrical double layer repulsion or steric repulsion depending on the surfactant type, concentration, ionic strength, and pH. Underdosing may result in high viscosity due to charge neutrality and hydrophobic attraction between particles while overdosing may result in high viscosity possibly due to micelles in the solution. The situation is particularly complicated for glazes containing limestone and anionic surfactant at moderate to low pH where calcium carbonate is soluble. The anionic surfactant and calcium ions can form complexes that are poorly soluble and strongly adsorb to the surface of the particles. The resulting thick steric layer of complexes produces a significant repulsion and stable, low viscosity suspensions. ζ potential measurements and adsorption isotherms are used to interpret the rheological behavior.     

Imag(e)ing the Urban Water Commons

The necessity and desire to control water, a vital resource for life, have generated deep, irreversible territorial transformations. Resting on the banks of the Sabarmati River, the Indian city of Ahmedabad has long celebrated water as a driver of urbanity and inclusive citizenship. This essay builds on the many natures of the urban water commons and examine the ever-changing relationship of the river and its city as a productive breeding ground for architectural and urban design experimentation. The societal construction of alternative, collective water imaginaries starts by recognizing the many cultural, spiritual, and symbolic meanings around water, connecting us with an increasingly distant nature. It is this elusive condition of water that drives the studio pedagogy explored in this essay. The projects adopt different formats and disciplinary positions while reclaiming the designers' cultural agency to advance socioenvironmental agendas and instigate political action.     

Effect of sodium dodecylbenzene sulfonate on the dispersion stability of ceramic glaze suspension

Sodium dodecylbenzene sulfonate (SDBS) was used to render the stability of ceramic glaze dispersion which is composed of limestone, feldspar, quartz, kaolin and ferric oxide. The measured zeta potential showed negative values for the systems in deionized water and 0.001 M MgCl₂ media at pH above 2, but a positive value was observed in 0.1M MgCl₂ at pH higher than 6.7. Adsorption of SDBS in aqueous suspensions of ceramic glaze in deionized water and in 0.001 M MgCl₂, within the concentration range studied, followed both the Langmuir and Freundlich isotherms, but the Freundlich isotherm was more favored. Adsorption of SDBS in 0.1M MgCl₂ corresponded to the Freundlich isotherm. From dispersion stability investigation, SDBS could render the suspension in deionized water and in 0.001 mM MgCl₂ more than in 0.1 mM MgCl₂.     

Fusion of multispectral and panchromatic satellite sensor imagery based on tailored filtering in the Fourier domain

A new methodology for fusing satellite sensor imagery, based on tailored filtering in the Fourier domain is proposed. Finite‐duration Impulse Response (FIR) filters have been designed through an objective criterion, which depends on source image characteristics only. The designed filters allow a weighted fusion of the information contained in a fine spatial resolution image (PAN) and in a multispectral image (MULTI), respectively, establishing a trade‐off between spatial and spectral quality of the resulting fused image. This new technique has been tested with Landsat Enhanced Thematic Mapper Plus (ETM+) imagery. Spatial and spectral quality of the fused images was compared with the results provided by Mallat's Wavelet algorithm. The images fused by the proposed method were characterized by a spatial resolution very close to the PAN image, and by the spectral resolution of the MULTI image.