Removal of E. coli from water using surface-modified activated carbon filter media and its performance over an extended use

Modification of activated carbon (AC) by aluminum hydroxychloride (AHC), and diatomaceous earth by zinc hydroxide changed the zeta potentials of these filter media from negative to positive. The modification method is amenable to room temperature, and eliminates the essential requirement of strong base treatment for making metal hydroxide coated filter media. Solid-state MAS 27Al NMR spectra suggested the presence of Al13-mer in the AHC-treated AC. AHC-modified AC samples were further treated with silver halide, and two antibacterial compounds to prevent microbial growth on filter media. In situ precipitation of silver bromide on AC resulted in formation of nanosized AgBr crystals. Bacteria removal performances of the modified media were tested in columns. For the first time, we demonstrated that only 30 g of either AHC-treated AC (60 x 200 mesh) or nano AgBr supported AC could provide >6 log E. coli removal over approximately 1000 L when the input water had a bacterial load of 10(7) CFU/mL. The filter media were robust enough to perform even when water was passed at superficial velocities 3-10 times the typical velocity (6 cm/min) of water treatment processes. Metal leaching from the modified media was found to be less than the USEPA specified Maximum Contaminant Level.     

Amorphous phenolphthalein-based poly(arylene ether)- modified cyanate ester networks: Microwave processing

Toughenability of cyanate ester networks with reactive hydroxyl-functionalized phenolphthalein-based amorphous poly(arylene ether sulfone) thermoplastics, via conventional thermal curing, without a sacrifice in either the T_g or the moderately high modulus of the unmodified cyanate ester networks was already demonstrated. The present article investigated the rapid processing of unmodified and thermoplastic-modified cyanate ester networks utilizing microwave radiation. Controlled morphologies were generated by variations in both the rates of conversion and the thermoplastic compositions. Improved toughness can be achieved which can be coupled with significantly reduced curing times. The use of nonreactive modifiers resulted in macrophase separation in contrast to the well-defined morphologies of the reactive thermoplastic-modified networks. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 179–190, 1997     

Effect of nanocrystalline binder on the microstructure and mechanical properties of ultrafine Ti(CN) cermets

The influence of highly deformed nanocrystalline binder ingredient on the overall microstructure and mechanical properties of ultrafine grade Ti(C_0.5N_0.5) cermet was investigated. Nanocrystalline Ni and Ni-aluminides viz. NiAl and Ni₃Al, synthesized by mechanical milling/alloying, were blended to the cermet powder prior to sintering. The mechanically milled nano-Ni contained a mixture of f.c.c. and hexagonal Ni phases. The cermet with nanocrystalline Ni showed a considerably improved microstructure over cermets with commercial coarse grade Ni and exhibits a high Vickers hardness of 16.1 GPa, along with a good fracture toughness value of 9 MPa m^1/2. However, no significant change in the mechanical properties could be detected in the case of nanocrystalline NiAl and Ni₃Al binder addition. The enhanced properties of the cermets containing nano-Ni were attributed to the finer particle size of the hard phase after sintering along with improved particle size distribution caused by rapid dissolution, which prevents excessive coalescence of the hard particles. On the other hand, the presence of high porosity in the cermets containing nano-NiAl and -Ni₃Al apparently nullified any such enhancement.     

A Study on Corrosion Resistance and Mechanical Performance of 6061 Aluminium Alloy: Galvanized Mild Steel Electron Beam Welds at Varying Welding Parameters

Transactions of the Indian Institute of Metals - Dissimilar welds of steel and aluminium alloys have an inherent problem of the vast difference in solid solubility which questions their integrity....     

An improved MOSFET model for circuit simulation

Problems that have continued to remain in some of the recently published MOSFET compact models are demonstrated in this paper. Of particular interest are discontinuities observed in these models at the boundary between forward and reverse mode operation. A new MOSFET model is presented that overcomes the errors present in state-of-the-art models. Comparison with measured data is also presented to validate the new model     

Strengthening Mechanisms in Mechanically Milled Oxide-Dispersed Iron Powders

Nanocrystalline iron and oxide dispersion-strengthened (ODS) iron powders (Fe, Fe-Y₂O₃, and Fe-Y₂O₃-Ti) were prepared by mechanical milling for periods ranging from 1 to 40 hours. The as-milled powders were examined for changes in their particle sizes, crystallite sizes, hardness values, and phases present as a function of milling time. Both the particle and the crystallite sizes of all the three compositions decreased with milling time, while the hardness values of all the three powders increased with milling time because of the crystallite size refinement. At the same crystallite size, the hardness values of Fe-Y₂O₃ and Fe-Y₂O₃-Ti powders were higher than that of the Fe powders. Though, the presence of 40 nm Y₂O₃ could be established for 2-hour milling, such particles were not resolvable in 40-hour-milled powders. However, SAD patterns confirmed the presence of complex oxide dispersoids in the Fe-Y₂O₃ and Fe-Y₂O₃-Ti powders. The variation of hardness value with the crystallite size and as a function of the milling time can be rationalized on the basis of Hall–Petch crystallite size strengthening in combination with dispersion strengthening (in Fe-Y₂O₃- and Fe-Y₂O₃-Ti-milled powders) due to dispersoids. The observed double-positive slopes in the Hall–Petch relationship can be explained in terms of an increase in misorientation angle between the crystallites with increasing milling time due to the crystallite rotation driven by disclination dipoles.     

Impact of leading edge delta-wing vortex generators on the thermal performance of a flat tube, louvered-fin compact heat exchanger

The effectiveness of delta-wing type vortex generators is experimentally evaluated by full-scale wind-tunnel testing of a compact heat exchanger typical to those used in automotive systems. The mechanisms important to vortex enhancement methods are discussed, and a basis for selecting a delta-wing design as a vortex generator is established. The heat transfer and pressure drop performance are assessed at full scale under both dry- and wet-surface conditions for a louvered-fin baseline and for a vortex-enhanced louvered-fin heat exchanger. An average heat transfer increase over the baseline case of 21% for dry conditions and 23.4% for wet conditions was achieved with a pressure drop penalty smaller than 7%. Vortex generation is proven to provide an improved thermal-hydraulic performance in compact heat exchangers for automotive systems.     

Comparison of SOI and junction isolation for substrate crosstalksuppression in mixed mode integrated circuits

Using two-dimensional computer simulations and measurements on silicon, it is shown that whereas silicon-on-insulator (SOI) based processes provide high isolation from crosstalk in mixed mode analogue-digital integrated circuits, p-i-n junction isolation can provide equal or better crosstalk immunity with less expense