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2011

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Articles 7531 - 7560 of 7765

Full-Text Articles in Physical Sciences and Mathematics

Modern Dirty Sea Ice Characteristics And Sources: The Role Of Anchor Ice, Dennis A. Darby, Wesley B. Myers, Martin Jakobsson, Ignatius Rigor Jan 2011

Modern Dirty Sea Ice Characteristics And Sources: The Role Of Anchor Ice, Dennis A. Darby, Wesley B. Myers, Martin Jakobsson, Ignatius Rigor

OES Faculty Publications

Extensive dirty ice patches with up to 7 kg m-2 sediment concentrations in layers of up to 10 cm thickness were encountered in 2005 and 2007 in numerous areas across the central Arctic. The Fe grain fingerprint determination of sources for these sampled dirty ice floes indicated both Russian and Canadian sources, with the latter dominating. The presence of benthic shells and sea weeds along with thick layers (2-10 cm) of sediment covering 5-10 m2 indicates an anchor ice entrainment origin as opposed to suspension freezing for some of these floes. The anchor ice origin might explain the …

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Use Of Sarima Models To Assess Data-Poor Fisheries: A Case Study With A Sciaenid Fishery Off Portugal, Nuno Prista, Norou Diawara, Maria J. Costa, Cynthia M. Jones Jan 2011

Use Of Sarima Models To Assess Data-Poor Fisheries: A Case Study With A Sciaenid Fishery Off Portugal, Nuno Prista, Norou Diawara, Maria J. Costa, Cynthia M. Jones

OES Faculty Publications

Research on assessment and monitoring methods has primarily focused on fisheries with long multivariate data sets. Less research exists on methods applicable to data-poor fisheries with univariate data sets with a small sample size. In this study, we examine the capabilities of seasonal autoregressive integrated moving average (SARIMA) models to fit, forecast, and monitor the landings of such data-poor fisheries. We use a European fishery on meagre (Sciaenidae: Argyrosomus regius), where only a short time series of landings was available to model (n=60 months), as our case-study. We show that despite the limited sample size, a SARIMA model could …

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Early Season Depletion Of Dissolved Iron In The Ross Sea Polynya: Implications For Iron Dynamics On The Antarctic Continental Shelf, Peter N. Sedwick, C. M. Marsay, B. M. Sohst, A. M. Aguilar-Islas, M. C. Lohan, M. C. Long, K. R. Arrigo, R. B. Dunbar, M. A. Saito, W. O. Smith, G. R. Ditullio Jan 2011

Early Season Depletion Of Dissolved Iron In The Ross Sea Polynya: Implications For Iron Dynamics On The Antarctic Continental Shelf, Peter N. Sedwick, C. M. Marsay, B. M. Sohst, A. M. Aguilar-Islas, M. C. Lohan, M. C. Long, K. R. Arrigo, R. B. Dunbar, M. A. Saito, W. O. Smith, G. R. Ditullio

OES Faculty Publications

The Ross Sea polynya is among the most productive regions in the Southern Ocean and may constitute a significant oceanic CO2sink. Based on results from several field studies, this region has been considered seasonally iron limited, whereby a "winter reserve" of dissolved iron (dFe) is progressively depleted during the growing season to low concentrations (~ 0.1 nM) that limit phytoplankton growth in the austral summer (December-February). Here we report new iron data for the Ross Sea polynya during austral summer 2005-2006 (27 December-22 January) and the following austral spring 2006 (16 November-3 December). The summer 2005-2006 data show …

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Crystallization And Preliminary X-Ray Crystallographic Analysis Of Ligand-Free And Arginine-Bound Forms Of Thermotoga Maritima Arginine-Binding Protein, Alessia Ruggiero, Jonathan D. Dattelbaum, Anna Pennacchio, Luisa Iozzion, Maria Staiano, Matthew S. Luchansky, Bryan S. Der, Rita Berisio, Sabato D'Auria, Luigi Vitagliano Jan 2011

Crystallization And Preliminary X-Ray Crystallographic Analysis Of Ligand-Free And Arginine-Bound Forms Of Thermotoga Maritima Arginine-Binding Protein, Alessia Ruggiero, Jonathan D. Dattelbaum, Anna Pennacchio, Luisa Iozzion, Maria Staiano, Matthew S. Luchansky, Bryan S. Der, Rita Berisio, Sabato D'Auria, Luigi Vitagliano

Chemistry Faculty Publications

The arginine-binding protein from Thermotoga maritima (TmArgBP) is an arginine-binding component of the ATP-binding cassette (ABC) transport system in this hyperthermophilic bacterium. This protein is endowed with an extraordinary stability towards thermal and chemical denaturation. Its structural characterization may provide useful insights for the clarification of structure– stability relationships and for the design of new biosensors. Crystallization trials were set up for both arginine-bound and ligand-free forms of TmArgBP and crystals suitable for crystallographic investigations were obtained for both forms. Ordered crystals of the arginine adduct of TmArgBP could only be obtained by using the detergent LDAO as an additive …

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Charge Saturation And Neutral Substitutions In Halomethanes And Their Group 14 Analogues, Bernard K. Wittmaack, Chad Crigger, Matthew Guarino, Kelling J. Donald Jan 2011

Charge Saturation And Neutral Substitutions In Halomethanes And Their Group 14 Analogues, Bernard K. Wittmaack, Chad Crigger, Matthew Guarino, Kelling J. Donald

Chemistry Faculty Publications

A computational analysis of the charge distribution in halomethanes and their heavy analogues (MH4-nXn: M= C, Si, Ge, Sn, Pb; X = F, Cl, Br, I) as a function of n uncovers a previously unidentified saturation limit for fluorides when M ≠ C. We examine the electron densities obtained at the CCSD, MP2(full), B3PW91, and HF levels of theory for 80 molecules for four different basis sets. A previously observed substituent independent charge at F in fluoromethanes is shown to be a move toward saturation that is restricted by the low polarizability of C. This limitation …

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Stabilizing Carbon-Lithium Stars, Nancy Perez-Peralta, Maryel Contreras, William Tiznado, John Stewart, Kelling J. Donald, Gabriel Merino Jan 2011

Stabilizing Carbon-Lithium Stars, Nancy Perez-Peralta, Maryel Contreras, William Tiznado, John Stewart, Kelling J. Donald, Gabriel Merino

Chemistry Faculty Publications

We have explored in silico the potential energy surfaces of the C5Linn-6 (n = 5, 6, and 7) clusters using the Gradient Embedded Genetic Algorithm (GEGA) and other computational strategies. The most stable forms of C5Li5-- and C5Li6 are two carbon chains linked by two lithium atoms in a persistent seven membered ring capped by two Li atoms. The other Li atoms are arrayed on the edge of the seven membered ring. In contrast, the global minimum structure for C5Li7+ is a bicapped star …

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Synthesis, Assembly, And Characterization Of Monolayer-Protected Gold Nanoparticle Films For Protein Monolayer Electrochemistry,, Tran T. Doan, Michael H. Freeman, Adrienne R. Schmidt, Natalie T. Nguyen, Michael C. Leopold Jan 2011

Synthesis, Assembly, And Characterization Of Monolayer-Protected Gold Nanoparticle Films For Protein Monolayer Electrochemistry,, Tran T. Doan, Michael H. Freeman, Adrienne R. Schmidt, Natalie T. Nguyen, Michael C. Leopold

Chemistry Faculty Publications

Colloidal gold nanoparticles protected with alkanethiolate ligands called monolayer protected gold clusters (MPCs) are synthesized and subsequently incorporated into film assemblies that serve as adsorption platforms for protein monolayer electrochemistry (PME). PME is utilized as the model system for studying electrochemical properties of redox proteins by confining them to an adsorption platform at a modified electrode, which also serves as a redox partner for electron transfer (ET) reactions. Studies have shown that gold nanoparticle film assemblies of this nature provide for a more homogeneous protein adsorption environment and promote ET without distance dependence compared to the more traditional systems modified …

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Study Of Differential Cross Section Using Different Bound State Potentials, Ass'ad I. Ass'ad Jan 2011

Study Of Differential Cross Section Using Different Bound State Potentials, Ass'ad I. Ass'ad

Turkish Journal of Physics

In this study, heavy ion reactions of ^6Li + (^{58}Ni, ^{28}Si, ^{12}C) and ^7Li + ^{12}C are studied using different bound state potentials, within the framework of the Distorted Wave Bourn Approximation (DWBA) calculations. Woods-Saxon potential is expressed as the optical potential in the initial and final channels together with a Coulomb potential. The calculations of the angular distributions are found to be in a good agreement with the experimental data. The extracted spectroscopic factors are reasonable.

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A Quantum Theory Of The Scattering Of Soft X-Ray From Compton Effect Caused Electron Standing Wave In The Materials, Biswajit Mallick Jan 2011

A Quantum Theory Of The Scattering Of Soft X-Ray From Compton Effect Caused Electron Standing Wave In The Materials, Biswajit Mallick

Turkish Journal of Physics

In the present investigation, low-energy x-rays (

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Uis Mapping Grades, Ph. Häuselmann Jan 2011

Uis Mapping Grades, Ph. Häuselmann

International Journal of Speleology

No abstract provided.

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Effective Size And Expansion Energy Of A Bose-Einstein Condensate In A 3d Non-Cubic Optical Lattice, Shemi S. M. Soliman Jan 2011

Effective Size And Expansion Energy Of A Bose-Einstein Condensate In A 3d Non-Cubic Optical Lattice, Shemi S. M. Soliman

Turkish Journal of Physics

This work is devoted to study the temperature dependence of the effective size and expansion energy E_{x,z} of a Bose-Einstein condensate in a 3D non-cubic optical lattice. Correction due to the finite size, interatomic interaction and the deepness of the lattice potential are given simultaneously. The calculated results show that these two parameters increase with the lattice depth or the relative frequency at temperature less than the transition temperature, (T < T_o); yet it has little effect at temperatures higher than the transition temperature (T > T_o). Both the effective size and expansion energy follow a characteristic temperature dependence, i.e. , E \propto(T/T_0)^4 if T < T_0 and , E \propto (T/T_0) if T > T_0. For a 3D non cubic optical potential the effect of …

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Analytical Expression For Mode-Coherence Coefficient Of A Uniformly-Distributed Wave Propagating In Different Homogeneous Media, Noor Ezzulddin Naji Jan 2011

Analytical Expression For Mode-Coherence Coefficient Of A Uniformly-Distributed Wave Propagating In Different Homogeneous Media, Noor Ezzulddin Naji

Turkish Journal of Physics

Presented is a derivation of an analytical expression for the mode-coherence coefficients of uniform-distributed wave propagating within different homogeneous media-as in the case of hyperbolic Gaussian beams-and a simple method involving the superposition of two such beams is proposed. The results obtained from this work are very applicable to study and analysis of Hermite-Gaussian beam propagation, especially in the problems of radiation-matter interaction, and laser beam propagation such as employed in free-space and fiber optical communications.

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Dynamical Behavior Of Traveling Wave Solutions For The K(2,2) Equation, Lina Zhang Jan 2011

Dynamical Behavior Of Traveling Wave Solutions For The K(2,2) Equation, Lina Zhang

Turkish Journal of Physics

In this paper, we discuss the qualitative behavior of degenerate singular points for the K(2,2) equation. By analyzing the different dynamical behaviors of the singular system and its associated regular system, we come to the conclusion that for the singular system the smoothness property of its orbits, which have intersection point(s) with the singular straight line, will not be destroyed. Meanwhile, the corresponding smooth traveling wave solutions for the K(2,2) equation are obtained.

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Resonant Transfer Excitation Followed By X-Ray For Boron-Like Ions, Hassan Ramadan Jan 2011

Resonant Transfer Excitation Followed By X-Ray For Boron-Like Ions, Hassan Ramadan

Turkish Journal of Physics

Theoretical cross sections for resonant transfer excitation followed by x-ray emission (RTEX) are calculated for the collisions of some ions in the series of the Boron-like ions with H_2 as a target. The calculations have been done for C II, N III, O IV, F V, Ar XIV and Fe XXII ions by folding their dielectronic recombination (DR) cross sections over the momentum distribution (Compton profile) of H_2 target gas. Calculations have been performed from both ground and metastable initial states, in LS - coupling, allowing for \triangle n = 0 excitations. In the present work, the RTEX cross sections …

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Electrons Trajectories In Electromagnetically Pumped Free Electron Laser With A Constant Reverse Guide Magnetic Field, Ahmad Omar Jan 2011

Electrons Trajectories In Electromagnetically Pumped Free Electron Laser With A Constant Reverse Guide Magnetic Field, Ahmad Omar

Turkish Journal of Physics

An exact solution to the quartic equation in the wiggler frequency \omega_w, which represents the dispersion relation for this system, is obtained. The effects of the frequency of the wiggler \omega_w on the electron's velocities (v_{\vert \vert} and v_w) are investigated. The regions of interest for the allowed wiggler frequency \omega_w for both group I and group II electron trajectories are discussed.

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Strong Optical Injection Locked Semiconductor Laser For High Bit Rate Chaotic Optical Communications, Muzahim Ibrahim Azawe, Ragaad Habib Saied Jan 2011

Strong Optical Injection Locked Semiconductor Laser For High Bit Rate Chaotic Optical Communications, Muzahim Ibrahim Azawe, Ragaad Habib Saied

Turkish Journal of Physics

We present in this article how strong optical injection can produce chaotic dynamics in the output of the semiconductor laser that is preferable for perfect encrypted optical communication networks. Significant increase in the relaxation resonance frequency was found implying higher degree of enhancement in modulation bandwidth. Numerical investigations under the condition of strong optical injection locking of the slave laser shows that instabilities in the photon number was observed and had settled down after a time of in the order of carrier lifetime. The model presented can be used to extract the characteristic parameters of the injection locking for detuning …

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2n-Dimensional At Fujii Model Instanton-Like Solutions And Coupling Constant's Role Between Instantons With Higher Derivatives, Mehmet Keçeci̇ Jan 2011

2n-Dimensional At Fujii Model Instanton-Like Solutions And Coupling Constant's Role Between Instantons With Higher Derivatives, Mehmet Keçeci̇

Turkish Journal of Physics

An instanton-like solution is considered for a class of two-dimensional conformal model with Liouville term. The model expressed here is a new higher-dimensional model with scalar-spinor interaction on even-dimensional spaces, and is a generalization of the even-dimensional Fujii model. A recurrence relation for the Fujii model and coupling constant's indices between relations with interaction constant is extracted. The behavior of Gürsey, Akdeniz-Smailagi' c and Fujii coupling constants in 4-dimensional conformal models are examined.

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Metals And Metal Oxides Particles Produced By Pulsed Laser Ablation Under High Vacuum, Khurram Siraj, Yasir Sohail, Aasma Tabassum Jan 2011

Metals And Metal Oxides Particles Produced By Pulsed Laser Ablation Under High Vacuum, Khurram Siraj, Yasir Sohail, Aasma Tabassum

Turkish Journal of Physics

A pulsed KrF Excimer laser (248 nm, 15 mJ) was utilized to synthesize different particles on (111) Si substrate under vacuum \sim 10^{-6} torr using Aluminum (Al), Platinum (Pt), Tungsten (W), Molybdenum (Mo), Cadmium Oxide (CdO), and Yttrium Oxide (Y_2O_3) targets. Scanning electron microscope (SEM) was used to study particle size distribution on silicon substrate. The size of individual metal particles was found to be ranging from 71 nm to 2 \mu m whereas metal oxides particles were found in the range of 71 nm to 1.1 \mu m. The particles below 100 nm are formed by gas phase condensation …

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Influence Of Doping And Heat Treatments On Carriers Mobility In Polycrystalline Silicon Thin Films For Photovoltaic Application, Beddiaf Zaidi, Bouzid Hadjoudja, Houda Felfli, Allaoua Chibani Jan 2011

Influence Of Doping And Heat Treatments On Carriers Mobility In Polycrystalline Silicon Thin Films For Photovoltaic Application, Beddiaf Zaidi, Bouzid Hadjoudja, Houda Felfli, Allaoua Chibani

Turkish Journal of Physics

In this work, we investigate the influence of doping as well as heat treatments on the mobility of the carriers in polycrystalline silicon layers. It was found that any increase in both parameters leads to an increase in the mobility of the carriers. Such mobilities were shown to be higher in boron doped layers that those doped with arsenic. Moreover, for strong arsenic doping, after the initial increase, we observed a saturation region followed by a final decrease of carrier mobility.

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Characteristics Cd_{0.3}Sn_{0.7}Se Thin Films As Absorber Materials For Solar Cell Devices, Salma Mahdi Shaban, Raad Mohammad Saleh, Ahmed Saleh Ahmed Jan 2011

Characteristics Cd_{0.3}Sn_{0.7}Se Thin Films As Absorber Materials For Solar Cell Devices, Salma Mahdi Shaban, Raad Mohammad Saleh, Ahmed Saleh Ahmed

Turkish Journal of Physics

Cadmium Tin Selenide compound Cd_{0.3}Sn_{0.7}Se was prepared by direct reaction of high-purity elemental Cadmium, Tin and selenium. Cd_{0.3}Sn_{0.7}Se thin films were prepared on to well-cleaned glass substrates by vacuum thermal evaporation technique at room temperature of different thicknesses. The X-ray diffraction studies revealed that all the deposited films are amorphous in nature and exhibiting polycrystalline structure when are annealed at 348 K and 373 K. The crystallites were found to have a preferred orientation along the (111) direction. The analysis of its optical characteristics indicated the ability of these films to absorb the visible light due to its graded energy …

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Effect Of Cdcl_2/Annealing On The Crystalline Transformation Of Cdte Thin Films Grown By Evaporation At A Low Substrate Temperature, İsmai̇l Polat, Sali̇h Yilmaz, Emi̇n Bacaksiz, Mustafa Altunbaş, Murat Tomaki̇n Jan 2011

Effect Of Cdcl_2/Annealing On The Crystalline Transformation Of Cdte Thin Films Grown By Evaporation At A Low Substrate Temperature, İsmai̇l Polat, Sali̇h Yilmaz, Emi̇n Bacaksiz, Mustafa Altunbaş, Murat Tomaki̇n

Turkish Journal of Physics

The structural and optical properties of CdTe thin films prepared at a low substrate temperature were investigated before and after the CdCl_2/annealing. The crystal structure of CdTe film was cubic with a strong (111) preferential orientation. Annealing at 400 °C without CdCl_2 treatment results in a decrease in the (111) peak intensity while the intensities of the (220), (311) and (331) peaks appeared, indicating that the texture is significantly changed. However, after the CdCl_2/annealing, the film exhibited a hexagonal phase as a dominant structure. The scanning electron microscopy patterns showed that the as-deposited and annealed samples had almost the same …

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Hydromagnetic Thermal Boundary Layer Flow Of A Perfectly Conducting Fluid, Kalidas Das Jan 2011

Hydromagnetic Thermal Boundary Layer Flow Of A Perfectly Conducting Fluid, Kalidas Das

Turkish Journal of Physics

Using successive approximation technique, an analysis of unsteady hydromagnetic boundary layer flow with thermal relaxation of perfectly conducting, viscous incompressible fluid past a semi-infinite porous plate in presence of heat absorbing sinks is carried out. The expression for velocity and temperature fields, local skin friction coefficient, local heat transfer coefficient etc have been derived when the free stream velocity exponentially depends on time. The effects of different parameters entering into the problem are shown graphically and discussed numerically.

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Electronic Structure Of The Ge And Se Vacancies In Gese Layered Semiconductor, Zakir Jahangirli Jan 2011

Electronic Structure Of The Ge And Se Vacancies In Gese Layered Semiconductor, Zakir Jahangirli

Turkish Journal of Physics

We report the results of a theoretical investigation of electronic properties of ideal cation and anion vacancies in GeSe. The calculations have been performed using self-consistent Green's function method. The bulk electronic structure is described by a tight-binding Hamiltonian in the bases sets of Linear Combinations of Atomic Orbitals (LCAO). The Green's function of the perfect crystal evaluated using an eigenfunction expansion employing wave functions and band structures obtained from a self-consistent, pseudopotential, local-density-functional calculation. The defect potential is calculated using occupied electron states of the perturbed system. Results are obtained in terms of vacancy bound states, vacancy resonances, and …

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A High Luminosity Erl On Ring E^-E^+ Collider For A Super Charm Factory, Erdal Recepoglu, Saleh Sultansoy Jan 2011

A High Luminosity Erl On Ring E^-E^+ Collider For A Super Charm Factory, Erdal Recepoglu, Saleh Sultansoy

Turkish Journal of Physics

A high luminosity energy recovery linac-on-ring type electron-positron collider operating as super charm factory is proposed. It is shown that a luminosity above L = 10^{35}cm^{-2}s^{-1} can be achieved for center of mass energy \sqrt{s}=3.77 GeV. The physics goals of this machine in investigation for charmed particles properties are briefly discussed.

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Editorial, Jo De Waele Jan 2011

Editorial, Jo De Waele

International Journal of Speleology

No abstract provided.

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Microwave-Induced Indium-Catalyzed Synthesis Of Pyrrole Fused With Indoline In Water, Dina Abrego, Debasish Bandyopadhyay, Bimal K. Banik Jan 2011

Microwave-Induced Indium-Catalyzed Synthesis Of Pyrrole Fused With Indoline In Water, Dina Abrego, Debasish Bandyopadhyay, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

An expeditious microwave-induced indium metal-catalyzed synthesis of pyrrole fused with indoline in water is developed by reacting isatin and 4-hydroxyproline.

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Microwave-Induced Bismuth Nitrate-Catalyzed Expeditious Enamination Of Β-Dicarbonyl Compounds Under Solvent-Free Conditions, Debasish Bandyopadhyay, Bimal K. Banik Jan 2011

Microwave-Induced Bismuth Nitrate-Catalyzed Expeditious Enamination Of Β-Dicarbonyl Compounds Under Solvent-Free Conditions, Debasish Bandyopadhyay, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Bismuth nitrate-catalyzed, automated microwave-assisted expeditious synthesis of β- enaminones and β-enaminoesters has been carried out in an efficient manner under solvent-free condition. The reaction is general for primary, secondary (cyclic, heterocyclic and acyclic), benzylic as well as aromatic amines.

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Microwave-Induced Stereoselectivity Of Β-Lactam Formation: Effects Of Solvents, Debasish Bandyopadhyay, Marco Yanez, Bimal K. Banik Jan 2011

Microwave-Induced Stereoselectivity Of Β-Lactam Formation: Effects Of Solvents, Debasish Bandyopadhyay, Marco Yanez, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Synthesis of 3, 4-disubstituted 2-azetidinones has been achieved following Staudinger reaction under microwave-induced conditions. The stereoselectivity of β-lactam formation depends on the nature of the solvents used in the reaction.

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Antimicrobial Activity Of Eugenol Derivatives, George Eyambe, Luis Canales, Bimal K. Banik Jan 2011

Antimicrobial Activity Of Eugenol Derivatives, George Eyambe, Luis Canales, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

The antibacterial properties of the clove plant are due to the presence of eugenol, an aromatic phenolic compound. Eugenol was isolated from clove by stem distillation. The alkene group in eugenol was epoxidized resulting in the synthesis of epoxide-eugenol. The heterocyclic ring in epoxide was cleaved to a bromoalcohol derivative. The compounds synthesized epoxideeugenol, bromo alcohol and euginol were tested for antimicrobial activity against Staphylococcus aureus (ATCC 25923). Epoxide-eugenol was found to be the most effective antimicrobial agent among the three compounds tested.

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Review: The Mathematics Of Sex: How Biology And Society Conspire To Limit Talented Women And Girls, Susan Jane Colley Jan 2011

Review: The Mathematics Of Sex: How Biology And Society Conspire To Limit Talented Women And Girls, Susan Jane Colley

Faculty & Staff Scholarship

No abstract provided.

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