Emad M. El-Giar

Localized Electrochemical Deposition of Copper Microstructures

This work demonstrates the electrodeposition of micrometer-scale copper structures using a simple instrument based on the scanning electrochemical microscope (SECM), Copper columns of 25 μm width up to about 2 mm high were deposited on different substrates and interconnects were grown within an integrated circuit package. In the present instrument electrodeposition is localized by applying a voltage between a closely spaced glass insulated Pt disk ultramicroelectrode, ca. 25 μm diam, and a substrate, all immersed in a solution of acidified CuSO 4 . The potential, the concentration of the CuSO 4 , and the presence of organic additives were all found to affect the microstructure of the deposits and control the efficiency of the deposition. To demonstrate some of the possible applications of this technique, copper lines were grown between pads in an integrated circuit package and an antenna about 2 cm long was grown on a millimeter wave transmission line cantilever.

Optical and Photovoltaic Characteristics of In‐Modified SnO2 Thin Films

thin films were prepared conveniently and reproducibly using the spray‐pyrolysis technique. This method enables the incorporation of foreign materials like indium in the matrix. The effect of In incorporation on the conductivity and optical properties of the prepared films was studied. The presence of In in the bulk of the film increases its conductivity and does not affect the optical properties to a significant extent. The energy gap of the prepared films was calculated for different layer thickness of pure and In‐incorporated films. Heterojunction solar cells were prepared and investigated using a standard potentiostatic technique. The power characteristics of the prepared photovoltaic cells were analyzed and compared with those of pure solar cells.

Localized electrochemical plating of interconnectors for microelectronics

This work demonstrates the electrodeposition of micrometer scale copper structures including columns and interconnectors. Copper interconnectors of 25 /spl mu/m width were grown within an integrated circuit package using a simple instrument based on the scanning electrochemical microscope. In the present instrument electrodeposition is localized by applying a voltage between a closely spaced glass insulated Pt disk tip (diameter ca. 25 /spl mu/m) and a substrate, all immersed in a plating solution of acidified CuSO/sub 4/. The parameters that affect the deposition process are also addressed.

Bioactive Natural, Biocatalytic, and Semisynthetic Tobacco Cembranoids

The two major Nicotiana tabacum tobacco cembranoids, (1 S,2 E,4 R,6 R,7 E,11 E)-2,7,11-cembratriene-4,6-diol (1) and its C-4 epimer, exhibit a wide range of interesting biological activities. Although the tumorigenesis inhibition activity of tobacco cembranoids have been known since the mid 1980s, only a limited number of investigations have targeted their optimization and structure-activity relationship. This study reports the isolation of the new (1 S,2 E,4 S,6 E,8 S,11 E)-2,6,11-cembratriene-8- O-methyl-4,8-diol (3) and the known (1 S,2 E,4 R,6 R,7 E,11 E)-2,7,11-cembratriene-4- O-methyl-4,6-diol (2) from fresh N. tabacum leaves. Cembranoid 2 showed good anti-migratory activity against prostate cancer cell lines, and was therefore subjected to microbial transformation and semisynthetic optimization studies. Biotransformation of 2 using the fungal strains Cunninghamella NRRL 5695 and Mucor ramannianus ATCC 9628 afforded new ( 4 and 5) and known ( 6 and 7) metabolites. Semisynthetic esterification, oxidation, epoxidation, and reaction with Lawessons reagent afforded the new products 8- 14. Cembranoid 2 and its epoxidation product 9 showed potent anti-migratory activities against the highly metastatic human prostate cancer cell lines PC-3M-CT+ (spheroid disaggregation assay) and PC-3 (wound-healing assay).

Characterization of bio-oils from the fast pyrolysis of white oak and sweetgum

Abstract Conversion of lignocellulosic biomass into bio-oil through fast pyrolysis process is considered one of the promising routes to supplement conventional fossil oil. Future bio-refineries require production large amounts of bio-oil from several biomass types. Characterization of the produced bio-oils is important to determine their suitability as bio-refinery feedstock. In this study, bio-oils were produced from white oak and sweetgum woods in an auger reactor at 450°C. The yields of char, liquid, and gas were calculated. The physical characterization of bio-oils was performed based on the investigation of different properties, such as pH, density, viscosity, water content, acid value, and molecular weight distribution of bio-oil components. The chemical compositions of the bio-oils were also investigated by gas chromatography/mass spectrometry and Fourier transform infra-red analyses. The physicochemical properties of the produced bio-oils were comparable to those obtained from similar woody biomass and the oils were suitable for fuel production.

Antimony-incorporated TiO2 thin films: preparation and optical and electrical characteristics

Antimony-incorporated TiO2 thin films were prepared using the spray-pyrolysis technique. The optical characteristics (percentage transmittance, refractive index, extinction coefficient) and the film thickness were investigated. The resistivity of the prepared samples was measured, and the effect of Sb concentration and film thickness on the measured parameters was discussed. The effect of Sb on the band-gap was also studied.

Hydrogel-Immobilized Antibodies for Microfluidic Immunoassays

The integration of immunoassays in microfluidic devices is a rapidly developing research area combining the power of immunoassays with the inherent benefits of microfluidics. Here, a general overview of microfluidic-based immunoassays is presented along with a method for immobilizing antibodies in polyacrylamide gel plugs set in microfluidic channels. These antigen-specific hydrogels can be rapidly formed by photopolymerizing monomer solutions mixed with antibodies or other large proteins. The resulting antigen-specific hydrogels contain pore sizes appropriate for physical entrapment of large antibodies while remaining permeable to smaller proteins. The open structure of these hydrogels enables the capture and concentration of target antigens present at low concentrations. Such physical entrapment provides a conceptually simple method of immobilization compared with immobilization of proteins on surfaces and offers advantages such as resistance to chemical and thermal denaturation.

6 – Development of magnetic nanoparticles for fluoride and organic matter removal from drinking water

Abstract Fluoride ion (F−) occurs naturally in all types of water. Groundwater may contain high levels of fluoride by exposure to inorganic fluoride-containing minerals causing teeth molting and lesion of endocrine glands, thyroid, and liver. High levels of natural, synthetic, and dissolved organics in water sources complicate coagulation techniques toward acceptable water quality. The challenges to have fresh, clean, and toxic-free drinking water motivated the search for effective, inexpensive, and environmentally acceptable disinfectants and decontaminants. The unique physicochemical properties and large surface-to-volume ratio of the nanomaterials make them very efficient, cost-effective, and attractive separation media for water purification. This chapter highlights the synthesis and use of magnetic nanoparticle compositions in the treatment of surface, ground, and wastewaters; with emphasis on the elimination of fluoride ions and organic matter. The chapter also covers the properties, advantages, and the challenges associated with the use of nanomaterials in the drinking water systems.

On laser welding of thin steel sheets

Abstract This paper presents a process–structure–property relationship study of laser welds as a continuous consolidation method for joining thin monophased steel foils, thereby providing a more effective, less costly method to construct automotive catalytic converters. A body centred cubic (bcc) iron–chromium–aluminium alloy doped with Mischmetal was utilised in this study. Both pulsed and continuous wave modes were used to establish the limit welding diagrams for lap joint configuration. Actual laser welding parameters were selected using several testing conditions. The laser welds behaved substantially different from the base material under creep and high temperature oxidation. The difference was mainly attributed to the changes in grain morphology, precipitation of aluminium nitrides and carbides, and relocalisation of the reactive elements during liquid metal flow upon keyhole formation, solidification and cooling.

Preparation, electrochemical, photoelectrochemical and solid-state characteristics of indium-incorporated TiO2 thin films for solar cell fabrication

Pure and indium incorporated titanium dioxide thin films were prepared using the spray/CVD technique. The incorporation of foreign atoms in the oxide film affects both the photovoltaic and photoelectrochemical characteristics of the heterojunction n-Si/TiO2. The presence of In in the titanium oxide matrix up to a film thickness of 100 nm had no effect on the transmittance of the oxide in the visible region. The conductivity and bandgap energy were found to increase with In-incorporation. The increased conductivity of the indium-containing oxide films is reflected in the improved photovoltaic properties of the prepared n-Si/TiO2- In solar cells. The photoelectrochemical properties of the prepared photoanodes revealed that the charge transfer step at the oxide/electrolyte interface leads to the deterioration of the device quality. A model for the effect of indium incorporation on the band structure of the TiO2 semiconducting film was suggested.