In the present study silver nanoparticles (Ag-NPs) were prepared by using chemical synthesis. Silver nanocolloid solution has been prepared chemically by the reduction of silver salt using sodium borohydride (NaBH4) and trisodium citrate (C6H5Na3O7.2H2O). Triangular silver nanoplates were also prepared by reducing silver salt using ascorbic acid which is a mild reducing agent. The nanoparticles were characterized by UV-VIS spectrophotometry and Scanning Electron Microscopy (SEM). The reducing character of ascorbic acid was used to determine the amount of ascorbic acid in real sample like vitamin C tablets that are available in the market of Bangladesh. Dhaka Univ. J. Pharm. Sci. 12(1): 29-33, 2013 (June) DOI: http://dx.doi.org/10.3329/dujps.v12i1.16297

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Nanocomposites of isotactic polypropylene (iPP) and multiwalled carbon nanotubes (MWCNTs) with various contents of MWCNTs were fabricated by double molding techniques. X-ray diffraction measurements reveal a development of a-crystal with lamellar stacks having a long period of 150 Å in the neat iPP that increases to 165 Å in 2 wt % MWCNTs-loaded composites, indicating that MWCNTs enhance crystallization of iPP as a nucleating factor. Mechanical properties, such as tensile strength, flexural strength, Young's modulus, tangent modulus, and microhardness are found to increase with increasing MWCNTs content. Thermal analyses represent an increase of crystallization and melting temperatures and a decrease of thermal stability of the composites with increasing MWCNTs. Changes in structural, mechanical, and thermal properties of the composites due to the addition of MWCNTs are elaborately discussed.

A conductivity probe having one electrode with a small surface (the sensing electrode) can be used for the measurement of the instantaneous local concentration during liquid mixing in an electrolytic solution. The presence of solid particles in the mixing field causes fluctuations of the electrolyte concentration signal, contaminating in this way the concentration measurement. The influences of the volume fraction and size of the solid particles on the electrolyte-concentration signal are investigated. The data indicate how to estimate the effect of the presence of particles in the specification of the electrolyte concentration. Furthermore, a method which allows the measurement of the mean electrolyte concentration at high solids volume fractions in electrolytic liquid/solid suspensions is proposed.

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