Parabolic Yao-type Geometric Spanners in Wireless Ad Hoc Networks

Artoun, Ojenie

Geometric graphs are frequently used to model a wireless ad hoc network in order to build efficient routing algorithms. The network topology in mobile wireless networks may often change therefore position-based routing that uses the idea of localized routing has an advantage over other types of routing protocols. Since a wireless network has limited memory and energy resources, topology control has an important role in enhancing certain desirable properties of these networks. ...

2010-01-11

Thesis

http://spectrum.library.concordia.ca/6792/1/Artoun_MCompSc_S2010.pdf ; Artoun, Ojenie (2010) Parabolic Yao-type Geometric Spanners in Wireless Ad Hoc Networks. Masters thesis, Concordia University.

Linear free-energy correlation analysis of the electronic effects of the substituents in the Sonogashira coupling reaction

Gottardo, Christine ; Kraft, Thomas M. ; Hossain, M. Selim ; Zawada, Peter V. ; Muchall, Heidi M.

Relative rate constants (krel) for the Sonogashira coupling were determined in competitive reactions between iodobenzene and a series of para- and meta-substituted iodobenzenes and compared to the charge on iodine and the z-component of the quadrupole moment of the iodine-bearing carbon. We use an Hammett correlation analysis and the computational data to provide further evidence that the rate limiting step of the Sonogashira reaction is the initial oxidative addition of Pd to ...

National Research Council Canada

2008-05

Article ; PeerReviewed

http://spectrum.library.concordia.ca/6761/1/Muchall_CanJChem2008.pdf ; Gottardo, Christine and Kraft, Thomas M. and Hossain, M. Selim and Zawada, Peter V. and Muchall, Heidi M. (2008) Linear free-energy correlation analysis of the electronic effects of the substituents in the Sonogashira coupling reaction. Canadian Journal of Chemistry, 86 (5). 410-415 . ISSN 0008-4042

Ionization potentials of nitriles — Photoelectron spectra of succinonitrile and glutaronitrile

Muchall, Heidi M. ; Werstiuk, Nick H.

The He(I) photoelectron spectra of succinonitrile (1) and glutaronitrile (2), both with extensive overlap of ionization bands in the low-energy region, are reported. To assign ionizations, we studied the conformational behaviour and resulting ionization energy dependence of 1 and 2 computationally with the B3LYP/6-31+G(d) model chemistry based on the fact that it reliably reproduces the ionization potentials of eleven mono- and di-nitriles, both saturated and unsaturated. The ...

National Research Council Canada

2006-09

Article ; PeerReviewed

http://spectrum.library.concordia.ca/6762/1/Muchall_CanJChem2006.pdf ; Muchall, Heidi M. and Werstiuk, Nick H. (2006) Ionization potentials of nitriles — Photoelectron spectra of succinonitrile and glutaronitrile. Canadian Journal of Chemistry, 84 (9). pp. 1124-1131. ISSN 0008-4042

A computational study of the 1,3-dipolar cycloaddition reaction mechanism for nitrilimines

Mawhinney, Robert C. ; Muchall, Heidi M. ; Peslherbe, Gilles H.

The [3+2] and [1+2] cycloaddition pathways between ethene and a series of 13 nitrilimines (R1CNNR2) have been examined by density functional theory [PBE0/6-311++G(2df,pd)] calculations. All reactions have low barriers ranging from 14.14 (R1 = CH3, R2 = H) to 1.01 (R1 = R2 = F) kcal mol–1, and large reaction exothermicities consistent with the transient nature of nitrilimines. The [3+2] and [1+2] transition-state structures are very similar, mainly differing in the relative orientation ...

National Research Council Canada

2005-09

Article ; PeerReviewed

http://spectrum.library.concordia.ca/6763/1/Muchall_CanJChem2005.pdf ; Mawhinney, Robert C. and Muchall, Heidi M. and Peslherbe, Gilles H. (2005) A computational study of the 1,3-dipolar cycloaddition reaction mechanism for nitrilimines. Canadian Journal of Chemistry, 83 (9). pp. 1615-1625. ISSN 0008-4042

Influence of the number of water molecules on the mechanism of N-sulfinylaniline hydrolysis

Ivanova, Elena V. ; Muchall, Heidi M.

The mechanism of the uncatalyzed hydrolysis of N-sulfinylaniline (Ph-N=S=O) has been studied with B3LYP/6-31+G(2d,2p) in the gas phase, with explicit treatment of water molecules. Hydrolysis involves water attack on sulfur, with a close to perpendicular alignment of a water molecule and the NSO plane in both prereaction complexes and transition states for the rate-determining step. Consequently, the distance of the weak S···O interaction, together with the efficiency of protonation ...

National Research Council Canada

2005-09

Article ; PeerReviewed

http://spectrum.library.concordia.ca/6764/1/Muchall_CanJChem2005b.pdf ; Ivanova, Elena V. and Muchall, Heidi M. (2005) Influence of the number of water molecules on the mechanism of N-sulfinylaniline hydrolysis. Canadian Journal of Chemistry, 83 (9). pp. 1588-1596. ISSN 0008-4042

A theoretical analysis of the conformational behaviour of substituted methylenecyclohexanes

Mawhinney, Robert C. ; Muchall, Heidi M. ; Lessard, Jean

The use of the PBE0 hybrid density functional theory method in conjunction with the COSMO solvation model allowed us to reproduce, both qualitatively and quantitatively, the experimentally observed conformational compositions of 2-substituted and 2,7-disubstituted methylenecyclohexanes. An analysis revealed several different interactions that influence the overall equilibrium. It was found that the endo (general) anomeric effect plays a significant role in the equilibrium and ...

National Research Council Canada

2003-10

Article ; PeerReviewed

http://spectrum.library.concordia.ca/6765/1/Muchall_CanJChem2003.pdf ; Mawhinney, Robert C. and Muchall, Heidi M. and Lessard, Jean (2003) A theoretical analysis of the conformational behaviour of substituted methylenecyclohexanes. Canadian Journal of Chemistry, 81 (10). pp. 1101-1107. ISSN 0008-4042

The conformational behaviour of methylenecyclohexanes revisited

Muchall, Heidi M. ; Kamya, Petrina RN ; Lessard, Jean

Conformational analyses on 2-substituted (methoxy, vinyloxy, and acetoxy) methylenecyclohexanes have been performed computationally with HF, B3LYP, PBE0, and MP2 and the 6-31G(d) basis set. The global minimum for the methoxy substituent is an axial conformer. For the vinyloxy substituent, except with PBE0, an axial conformer is determined as the global minimum. The acetoxy substituent prefers the equatorial orientation. This sequence is in keeping with the operation of an "unsaturation ...

National Research Council Canada

2003-06

Article ; PeerReviewed

http://spectrum.library.concordia.ca/6766/1/Muchall_CanJChem2003b.pdf ; Muchall, Heidi M. and Kamya, Petrina RN and Lessard, Jean (2003) The conformational behaviour of methylenecyclohexanes revisited. Canadian Journal of Chemistry, 81 (6). pp. 689-696. ISSN 0008-4042

A computational study on the sources of deuterium secondary kinetic isotope effects in carbocation-forming reactions

Muchall, Heidi M. ; Werstiuk, Nick H

Calculations at the HF-DFT hybrid Becke3LYP level of theory have been undertaken on protonated 2-exo- and 2-endo-norbornanols as model substrates for 2-exo- and 2-endo-norbornyl brosylates to explore the source of the experimentally determined deuterium secondary kinetic isotope effects (KIEs). Calculations on protonated alcohols as models reproduce the "normal" behaviour of 2-endo substrate 5. The observed endo g-KIE in the 7-unsubstituted 2-exo system 4 is shown to arise from ...

National Research Council Canada

1998-12

Article ; PeerReviewed

http://spectrum.library.concordia.ca/6767/1/Muchall_CanJChem1998.pdf ; Muchall, Heidi M. and Werstiuk, Nick H (1998) A computational study on the sources of deuterium secondary kinetic isotope effects in carbocation-forming reactions. Canadian Journal of Chemistry, 76 (12). pp. 1926-1930. ISSN 0008-4042

A study of the vacuum pyrolysis of para-substituted diazoacetophenones with He(I) ultraviolet photoelectron spectroscopy

Werstiuk, Nick H ; Muchall, Heidi M. ; Ma, Jiagong ; Liu, Michael TH

An ultraviolet photoelectron (PE) spectrometer apparatus that utilizes a tuneable 50 W CW CO2 laser as a directed heat source was used to study the vacuum pyrolysis of diazoacetophenone (1a) and its p-methyl, p-methoxy, p-chloro, and p-nitro analogues 1b, 1c, 1d, and 1e. Analysis of the pyrolysate with He(I) ultraviolet PE spectroscopy shows that at a laser power level of 26 W (500 ± 50°C) 1a, 1b, 1c, and 1d, cleanly yield the corresponding phenylketenes 2a, 2b, 2c, and 2d, respectively, ...

National Research Council Canada

1998-08

Article ; PeerReviewed

http://spectrum.library.concordia.ca/6768/1/Muchall_CanJChem1998b.pdf ; Werstiuk, Nick H and Muchall, Heidi M. and Ma, Jiagong and Liu, Michael TH (1998) A study of the vacuum pyrolysis of para-substituted diazoacetophenones with He(I) ultraviolet photoelectron spectroscopy. Canadian Journal of Chemistry, 76 (8). pp. 1162-1173. ISSN 0008-4042

A calculational and ultraviolet photoelectron spectroscopic study of distorted amides

Werstiuk, Nick H ; Muchall, Heidi M. ; Roy, C.D. ; Ma, J. ; Brown, R.S.

Distorted amides 3,4-dihydro-2-oxo-1,4-ethanoquinoline (1a), 3,4-dihydro-2-oxo-1,4-propanoquinoline (1b), 3,3,4,5-tetrahydro-2-oxo-1,5-ethanobenzazepine (1c), and 3,3,4,5-tetrahydro-2-oxo-1,5-propanobenzazepine (1d) and the model compounds 2,N-dimethyl-acetanilide (2a), 2,N,N-trimethylaniline (3), and benzoquinuclidine (4) have been studied calculationally and with He(I) ultraviolet photoelectron spectroscopy. We find good agreement between experimentally obtained ionization energies ...

National Research Council Canada

1998-06

Article ; PeerReviewed

http://spectrum.library.concordia.ca/6769/1/Muchall_CanJChem1998c.pdf ; Werstiuk, Nick H and Muchall, Heidi M. and Roy, C.D. and Ma, J. and Brown, R.S. (1998) A calculational and ultraviolet photoelectron spectroscopic study of distorted amides. Canadian Journal of Chemistry, 76 (6). pp. 672-677. ISSN 0008-4042