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Al - Hassa, Saudi Arabia

King Faisal University is a public university with the main campus in the city of Hofuf in Al-Hassa, Saudi Arabia founded in 1975. KFU was initially established with four colleges: two in Dammam and the other two in Al-Ahsa. Wikipedia.

The influence of chain length on the composition of mixed micelles in binary mixtures of N,N-dimethyldodecan-1-amine oxide (DDAO) and decyl-, dodecyl-, and tetradecyl-trimethyl-ammonium bromide surfactants (abbreviated as C 10TAB, C 12TAB, and C 14TAB, respectively) has been determined at 298 K. From the surface tension measurements, the critical micelle concentration (cmc) data were measured as a function of mixing composition. The cmc values were then analyzed according to regular solution model. The composition of mixed micelles, the interaction parameter (ß), and the activity coefficients were evaluated from the regular solution model for all cationic-amphoteric mixed systems. The interaction parameter values indicated somehow a small deviation from ideality for the three mixed surfactant systems, for all investigated mole fractions. The strength of the interaction between the amphoteric surfactant and the alkyl-trimethyl-ammonium bromide surfactants in three mixed systems obeys the following order: (C 10TAB + DDAO) > (C 12TAB + DDAO) > (C 14TAB + DDAO) suggesting that the decrease in the length of cationic surfactant alkyl chain results in a stronger interaction with DDAO. Rheological measurements of these solutions in the presence of sodium salicylate, NaSal, for the three mixed systems were also measured. The viscosity data reveal a viscosity increasing trend of (C 14TAB + DDAO) > (C 12TAB + DDAO) > (C 10TAB + DDAO). © 2012 American Chemical Society.

Idris A.M.,King Faisal University
Critical Reviews in Analytical Chemistry | Year: 2010

Since their introduction in the mid-1970s, flow injection (FI) techniques have gained a worldwide popularity. FI techniques are automated, miniaturized, versatile, and inexpensive analytical tools for handling reagents and samples and consequently for conducting procedures related to wet chemical analysis. Due to their tremendous benefits, FI techniques have proven to be significant applications to such analytical fields as pharmaceutical, environmental, biochemical, and food. Currently, more than 10,000 publications reporting various applications of FI techniques can be retrieved from the literature. However, FI techniques have not yet received an adequate attention to the field of forensic analysis; less than 30 publications were reported. The main objective of the current article is to draw attention to the potential of FI techniques to forensic analytical chemists. The article provides a comprehensive review of the applications of FI techniques to forensic chemical analysis, which covers the literature since the inception of the techniques. The article also offers a brief historical background on the developments of the generation and versions of the techniques while highlighting their advantages. In addition, future perspectives in the applications of FI techniques to forensic analysis are discussed. © Taylor and Francis Group, LLC.

Idris A.M.,King Faisal University
Critical Reviews in Analytical Chemistry | Year: 2010

The ever increasing demand for rapid, cost-effective, practically-safe, and environmentallybenign analytical methods has aroused researchers to develop automated, miniaturized, versatile, and inexpensive analytical techniques. Flow injection (FI) techniques were well-established to meet the requirements of modern chemical analysis. The family of FI techniques includes three generations, flow injection analysis (FIA), sequential injection analysis (SIA), and bead injection analysis (BIA). In addition, new versions of SIA, micro-SIA-lab-on-valve (μSIA-LOV), and sequential injection chromatography (SIC), have recently been developed for more downscaling analysis and broadening applications. In the literature, we have not found a comprehensive and updated manuscript presenting all generations and recent versions of FI techniques. Therefore, the current manuscript briefly demonstrates the principles, developments, and applications of the FI techniques along with their consequent generations and recent versions. © Taylor and Francis Group, LLC.

2,5-Disubstituted tetrahydrofurans constitute the core skeleton of several natural products and are pivotal synthetic analogues of medicinal importance that exhibit remarkable bioactivities. Oxasqualenoid natural products are implicated as potent biologically active molecules, particularly with regard to demonstrating significant cytotoxicity. Characteristic features of oxasqualenoids containing tetrahydrofuran fragments include the presence of a cis- and/or trans-2,5-disubstituted pattern in tetrahydrofuran moieties, and molecular symmetry is often noticed as well. Given their unique structural features combined with their bioactivity, two representative examples from this class of natural products, eurylene and teurilene, have been briefly reviewed. Eurylene, with reported cytotoxicity against lymphocytic leukemia, contains two non-adjacent linked cis- and trans-2,5-disubstituted tetrahydrofuran rings and a combined total of eight stereogenic centres. It is a chiral molecule due to the lack of a C2 axis of symmetry. Teurilene shows a prominent cytotoxicity on KB cells and has three adjacently linked 2,5-disubstituted tetrahydrofurans. A distinctive achiral facet is observed in teurilene, despite having eight stereocentres, due to the presence of meso symmetry (C s). The prime objective of this account is to describe a precise mechanistic insight for both cis- and trans-2,5-disubstituted tetrahydrofurans present in these natural products and to highlight the exciting challenges encountered during the installation of functionalities or structural motifs en route to their synthetic approaches. This journal is © the Partner Organisations 2014.

Talla J.A.,King Faisal University
Chemical Physics | Year: 2012

The interactions between oxygen and nitrogen atoms with single-walled carbon nanotubes were investigated for nanotubes with two different geometrical configurations using first-principle calculations within the framework of the density functional theory. We introduced a new type of toxic gas sensor that can detect the presence of H 2, Cl 2, CO, and NO molecules. We also demonstrated that the sensitivity of this device can be controlled by the concentration of the dopants on the surface of the nanotube. In addition, the transport properties of the doped nanotube were studied for different concentrations of oxygen or nitrogen atoms that were randomly distributed on the surface of the single-walled carbon nanotube. We observed that small amounts of dopants can modify the electronic and transport properties of the nanotube and can lend metallic properties to the nanotube. Band-gap narrowing occurs when the nanotube is doped with either oxygen or nitrogen atoms. © 2011 Elsevier B.V. All rights reserved.

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