A New Mathematical Model for Calculating the Electronic Coupling of a B-DNA Molecule
Dale J. Igram,
Jason W. Ribblett,
Eric R. Hedin,
Yong S. Joe
Issue:
Volume 5, Issue 2, April 2016
Pages:
17-25
Received:
8 February 2016
Accepted:
15 February 2016
Published:
9 March 2016
Abstract: The charge transport properties of DNA have made this molecule very important for use in nanoscale electronics, molecular computing, and biosensoric devices. Early findings have suggested that DNA can behave as a conductor, semiconductor, or an insulator. This variation in electrical behavior is attributed to many factors such as environmental conditions, base sequence, DNA chain length, orientation, temperature, electrode contacts, and fluctuations. To better understand the charge transport characteristics of a DNA molecule, a more thorough understanding of the electronic coupling between base pairs is required. To achieve this goal, two mathematical methods for calculating the electronic interactions between base pairs of a DNA molecule have been developed, which utilize the concepts from Molecular Orbital Theory (MOT) and Electronic Band Structure Theory (EBST). The electronic coupling characteristics of a B-DNA molecule consisting of two Guanine-Cytosine base pairs have been examined for variation in the twist angle between the base pairs, the separation between base pairs, and the separation between base molecules in a given base pair, for both the HOMO and LUMO states. Comparison of results to published literature reveals similar outcomes. The electronic properties (metallic, semi-conducting, insulating) of a B-DNA molecule are also determined.
Abstract: The charge transport properties of DNA have made this molecule very important for use in nanoscale electronics, molecular computing, and biosensoric devices. Early findings have suggested that DNA can behave as a conductor, semiconductor, or an insulator. This variation in electrical behavior is attributed to many factors such as environmental cond...
Show More
Characteristics of Polymer Concrete from Pumice Stone and Rubber Thread Waste with Polyurethane as Natural Bonding
Fauzi,
Tamrin,
Anwar Dharma Sembiring,
Ridwan Abdullah Sani
Issue:
Volume 5, Issue 2, April 2016
Pages:
26-34
Received:
1 March 2016
Accepted:
15 March 2016
Published:
29 March 2016
Abstract: In this study, the aggregate of polymer concrete is made using pumice stone, sand, solid waste rubber thread, and polyurethane as a binder. Variation of composition of sand and pumice are (1: 1) or (50 g: 50 g); solid waste rubber thread are (0, 2, 4, 6, 8, 10)% of the total weight of sand and pumic; while composition variations of polyurethane are (10, 15, 20)% of the total weight of sand and pumice. The measured parameters of samples are density, water absorption, porosity, compressive strength, impact strength, flexural strength, microstructure analysis using Scanning Electron microscope (SEM), XRD analysis and sound absorption coefficient. Based on this research, it is showed that the optimum conditions of fabricated polymer concrete characteristics are with density of 1.67 g/cm3, water absorption of 13.25%, porosity of 19.85%, the compressive strength is 8.59 MPa, impact strength of 5.2 kJ, and flexural strength of 50.33 MPa). The sound absorption coefficient of the best sample is 0.196. This polymer concrete is lighter than conventional concrete and has better strength and sound absorption coefficient.
Abstract: In this study, the aggregate of polymer concrete is made using pumice stone, sand, solid waste rubber thread, and polyurethane as a binder. Variation of composition of sand and pumice are (1: 1) or (50 g: 50 g); solid waste rubber thread are (0, 2, 4, 6, 8, 10)% of the total weight of sand and pumic; while composition variations of polyurethane are...
Show More
Influence of Pretreatment with Soda (NaOH) on the Structural Characteristics of Activated Carbon Prepared by Chemical Means with H3PO4 from Rice Bran
Clément K. Balogoun,
Ibrahim Tchakala,
Mike Medokponou,
Moctar L. Bawa,
Dominique C. Sohounhloue
Issue:
Volume 5, Issue 2, April 2016
Pages:
35-44
Received:
10 March 2016
Accepted:
19 March 2016
Published:
30 March 2016
Abstract: The purpose of this work is the preparation of best activated carbons from rice bran through carbonization at 500°C preceded by an impregnation in a 25% H3PO4 solution. We carry out the study of the effects of pretreatment with soda and Xp impregnation ratio on characteristics of three series of activated carbons SR0N, SR1N and SR2N corresponding to the pre-treatment with soda 0 M, 1 M and 2 M respectively. The iodine value and the textural properties of prepared carbons have been determined. The maximum iodine value, 893 mg.g-1 is obtained in the SR2N series for Xp = 2.5. In the SR1N series the maximum iodine value 866 mg.g-1 is obtained for Xp = 4. Also activated carbons CS1 (SR1N - Xp = 4) and CS2 (SR2N - Xp = 2.5) have the following characteristics: specific surface area equal to 1711.6 and 1558.5 m2g-1 and porous volumes of 1.234 and 1.385 cm3/g respectively. Studies conducted on phenol adsorption and thermodynamic showed that CS1 is slightly more effective than CS2 with a spontaneous and exothermic reaction. On the other hand, their adsorption isotherms are best described by the Langmuir model than that of Freundlich.
Abstract: The purpose of this work is the preparation of best activated carbons from rice bran through carbonization at 500°C preceded by an impregnation in a 25% H3PO4 solution. We carry out the study of the effects of pretreatment with soda and Xp impregnation ratio on characteristics of three series of activated carbons SR0N, SR1N and SR2N corresponding t...
Show More
