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2004

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Articles 4081 - 4110 of 4447

Full-Text Articles in Physical Sciences and Mathematics

Synthesis, Magneto-Spectral And Thermal Characteristics Of Some 7-Coordinated Compounds Of Lanthanides(Iii) Chlorides With 4[(Furan-2-Ylmethylene)Amino]-1,5-Dimethyl-2-Phenyl Pyrazol-3-One And Isonicotinic Acid(3',4',5'-Trimethoxybenzylidene)Hydrazide, Ram K. Agarwal, Surendra Prasad, Neetu Goel Jan 2004

Synthesis, Magneto-Spectral And Thermal Characteristics Of Some 7-Coordinated Compounds Of Lanthanides(Iii) Chlorides With 4[(Furan-2-Ylmethylene)Amino]-1,5-Dimethyl-2-Phenyl Pyrazol-3-One And Isonicotinic Acid(3',4',5'-Trimethoxybenzylidene)Hydrazide, Ram K. Agarwal, Surendra Prasad, Neetu Goel

Turkish Journal of Chemistry

In the present work, we describe the isolation of some lanthanide(III) chlorides coordination compounds with 4[(furan-2-ylmethylene)amino]-1,5-dimethyl-2-phenyl pyrazol-3-one (FDPPO) and isonicotinic acid(3',4',5'-trimethoxybenzylidene)hydrazide (ITMBH) with the general composition [Ln(L)_2Cl_3] (Ln = La, Pr, Nd, Sm, Gd, Tb, Dy or Ho; L = FDPPO or ITMBH). All the isolated compounds were characterized through various physico-chemical studies. The coordinating ligands FDPPO or ITMBH act as neutral bidentate N and O-donors in the present compounds. The central metal ion displays the coordination number 7 in these complexes. Thermal stabilities of these complexes were also studied through thermogravimetric analysis.


Diffusion Effect On The Anodic Reactions Of Tungsten, Mustafa Anik, Tuba Cansizoğlu, Si̇nem Çevi̇k Jan 2004

Diffusion Effect On The Anodic Reactions Of Tungsten, Mustafa Anik, Tuba Cansizoğlu, Si̇nem Çevi̇k

Turkish Journal of Chemistry

Potentiodynamic and potentiostatic polarizations, and a rotating disk electrode technique were used to study the influence of diffusion on the anodic reactions of tungsten (W) in a broad pH range (\sim 0.3--13.5) in H_3PO_4 buffered solutions. The anodic current was controlled totally by the kinetics of H^+ -assisted dissolution below pH 1 (Region A). At around pH 2.5 (Region B), in addition to the kinetics of H_2O-assisted dissolution, specimen rotation had an effect on the current. This observation was attributed mainly to the physical damage to an oxide phase by hydrodynamic effects and partly to the diffusion of surface H_2WO_4(aq) …


Synthesis And Microbiological Activity Of Some Substituted N-(2-Hydroxy-4-Nitrophenyl)Benzamides And Phenylacetamides As Possible Metabolites Of Antimicrobial Active Benzoxazoles, İlkay Yildiz Ören, Esi̇n Aki Şener, Cengi̇z Ertaş, Özlem Temi̇z Arpaci, İsmai̇l Yalçin, Nurten Altanlar Jan 2004

Synthesis And Microbiological Activity Of Some Substituted N-(2-Hydroxy-4-Nitrophenyl)Benzamides And Phenylacetamides As Possible Metabolites Of Antimicrobial Active Benzoxazoles, İlkay Yildiz Ören, Esi̇n Aki Şener, Cengi̇z Ertaş, Özlem Temi̇z Arpaci, İsmai̇l Yalçin, Nurten Altanlar

Turkish Journal of Chemistry

Some new antimicrobial active N-(2-hydroxy-4-nitrophenyl)- p-substituted benzamide and phenylacetamide analogues (I-II) were prepared by 2-step procedures from the corresponding carboxylic acids as possible metabolites of benzoxazoles. Their antimicrobial activities were tested against 3 Gram-positive and 2 Gram-negative bacteria with the fungus Candida albicans and were also compared with several control drugs. The compounds Ia, Id, IIa, and IIe were active at a MIC value of 12.5 \mu g/mL against the Gram-positive microorganism Bacillus subtilis. Most of the compounds exhibited antifungal activity at a MIC value of 12.5 \mu g/mL against C. albicans. On the other hand, the antimicrobial activity of …


Synthesis And Antinociceptive Activity Of 2-[(2-Oxobenzothiazolin-3-Yl)Methyl]- 5-Aminoalkyl/Aryl-1,3,4-Thiadiazole, Ti̇jen Önkol, Bi̇lge Çakir, M. Fethi̇ Şahi̇n, Engi̇n Yildirim, Kevser Erol Jan 2004

Synthesis And Antinociceptive Activity Of 2-[(2-Oxobenzothiazolin-3-Yl)Methyl]- 5-Aminoalkyl/Aryl-1,3,4-Thiadiazole, Ti̇jen Önkol, Bi̇lge Çakir, M. Fethi̇ Şahi̇n, Engi̇n Yildirim, Kevser Erol

Turkish Journal of Chemistry

Ten 2-[(2-oxobenzothiazolin-3-yl)methyl]-5-aminoalkyl/aryl-1,3,4-thiadiazole derivatives were synthesized. The chemical structures of these compounds were elucidated by their FT-IR and ^1H-NMR spectral data, as well as their elemental analyses. The compounds were tested for antinociceptive activity. Among these compounds, 2-[(2-oxobenzothiazolin-3-yl)methyl]-5-aminomethyl-1,3,4-thiadiazole (5a) was found to be significantly more active than the others and the standards in all the tests.


The Hydrodynamic Properties Of Micelles Formed By Block Copolymers Of Isoprene And Tert-Butylacrylate In N-Octane, Hali̇l İbrahi̇m Ünal, Colin Price Jan 2004

The Hydrodynamic Properties Of Micelles Formed By Block Copolymers Of Isoprene And Tert-Butylacrylate In N-Octane, Hali̇l İbrahi̇m Ünal, Colin Price

Turkish Journal of Chemistry

The hydrodynamic properties of micelles formed by 2 block copolymers of isoprene and tert-butylacrylate in n-octane were investigated by dynamic light scattering (DLS) over a range of temperatures and concentrations using both the cumulants and histogram methods. By means of the histogram method it was possible to determine the average hydrodynamic diameters of both micelles and unassociated-chains in the same solution. It was also used to determine the z-average fraction of unassociated-chains at a particular concentration and temperature, and it provided an alternative route when combined with static light scattering (SLS) for determining the thermodynamics of micellisation. The overall-average diffusion …


Synthesis And Characterization Of Block Copolymers Using Polysiloxane Based Macroazoinitiator, Sennur Deni̇z, Ni̇l Baran, Mesut Akgün, Nalan A. Akgün, Sali̇h Di̇nçer Jan 2004

Synthesis And Characterization Of Block Copolymers Using Polysiloxane Based Macroazoinitiator, Sennur Deni̇z, Ni̇l Baran, Mesut Akgün, Nalan A. Akgün, Sali̇h Di̇nçer

Turkish Journal of Chemistry

Poly(dimethylsiloxane-b-styrene) (PDMS-b-PSt) and poly(dimethylsiloxane-b-methyl methacrylate) (PDMS-b-PMMA) block copolymers containing siloxane segments were studied by the radical polymerizations of vinyl monomers such as styrene (St) and methyl methacrylate (MMA) using polydimethylsiloxane based macroazoinitiator (PDM-MAI) in solution. PDM-MAI was synthesized by reacting hydroxy-terminated polydimethylsiloxane (PDMS) and 4,4'-azobis (4-cyanopentanoyl chloride) (ACPC) having a thermodegradable azo-linkage. The polycondensation reaction between PDMS and ACPC (2:1, molar ratio) was carried out at room temperature. The polymerizations of St and MMA initiated by PDM-MAI were investigated using different PDM-MAI concentrations (1, 5, 10, and 15 wt. %) for various reaction times with a methyl ethyl ketone (MEK)/ …


Studies On The Reactions Of 4-Ethoxycarbonyl-5-Phenyl-2,3-Dihydro-2,3- Furandione With Some Nh Nucleophiles, Ahmet Şener, Hasan Genç, İsrafi̇l Tozlu, M. Kasim Şener Jan 2004

Studies On The Reactions Of 4-Ethoxycarbonyl-5-Phenyl-2,3-Dihydro-2,3- Furandione With Some Nh Nucleophiles, Ahmet Şener, Hasan Genç, İsrafi̇l Tozlu, M. Kasim Şener

Turkish Journal of Chemistry

4-Ethoxycarbonyl-5-phenyl-2,3-dihydro-2,3-furandione 1 was reacted with o-phenylenediamine, substituted ureas and methylcarbamate or acetamide to give quinoxaline 2, pyrimidine 3 and benzoylmalonic acid 4 derivatives, respectively. Benzoylmalonic acid derivative 4a was converted into a new oxozinedione derivative, 5, by refluxing its solution in xylene containing a catalytic amount of p-toluene sulfonic acid. In addition, triphenylpyrazole carboxylic acid derivative 6 was obtained from the reaction of 4a with diphenylhydrazine.


The Crystal And Molecular Structure Of 1-(2-Chloro-Benzoyl)-3-P-Tolyl-Thiourea, Hakan Arslan, Ulrich Flörke, Nevzat Külcü Jan 2004

The Crystal And Molecular Structure Of 1-(2-Chloro-Benzoyl)-3-P-Tolyl-Thiourea, Hakan Arslan, Ulrich Flörke, Nevzat Külcü

Turkish Journal of Chemistry

1-(2-Chloro-benzoyl)-3-p-tolyl-thiourea was synthesized and characterized by elemental analysis and IR spectroscopy. The crystal and molecular structure of the title compound was determined from single-crystal X-ray diffraction data. It crystalizes in the triclinic space group P-1, with a = 7.9942(9) Å, b = 9.531(1) Å, c = 11.075(1) Å, \alpha = 97.235(2) °, \beta = 111.099(2) °, and \gamma = 106.105(2) °.


Secondary Metabolites From Phlomis Kotschyana, Ü. Şebnem Harput, İclal Saracoğlu, İhsan Çaliş, Ali̇ Arslan Dönmez, Akito Nagatsu Jan 2004

Secondary Metabolites From Phlomis Kotschyana, Ü. Şebnem Harput, İclal Saracoğlu, İhsan Çaliş, Ali̇ Arslan Dönmez, Akito Nagatsu

Turkish Journal of Chemistry

A lignan glycoside, syringaresinol-4',4''-O-di-\beta -D-glucopyranoside (1) (=liriodendrin), 4 phenylethanoid glycosides, acteoside (2), isoacteoside (3), forsythoside B (4) and leucosceptoside B (5), a caffeic acid ester, chlorogenic acid (6) and 2 iridoid glucosides, lamiide (7) and auroside (8), were isolated from the methanolic extracts of the aerial parts of Phlomis kotschyana along with an acetophenone glycoside, 4-hydroxyacetophenone 4-O-[6'-O-\beta -D-apiofuranosyl]-\beta -D-glucopyranoside (9). The structures of the isolated compounds were identified on the basis of spectroscopic (UV, IR, 1D- and 2D-NMR, and FAB-MS) methods.


Trace- And Rare-Earth Element Geochemistry Of The Karalar (Gazipaşa-Antalya) Barite-Galena Deposits, Southern Turkey, Gülcan Bozkaya, Ahmet Gökçe Jan 2004

Trace- And Rare-Earth Element Geochemistry Of The Karalar (Gazipaşa-Antalya) Barite-Galena Deposits, Southern Turkey, Gülcan Bozkaya, Ahmet Gökçe

Turkish Journal of Earth Sciences

The Karalar barite-galena deposits are typical examples of carbonate-hosted barite-galena deposits that occur widely in the central Taurides. Recent mining activity has been concentrated in the Büyük and Boyalık mine areas. The mineralisation occurs as ore veins along fault zones and as ore-filled breccia zones along the strongly deformed lower walls of limestone blocks in the Permian limestones of the Bıçkıcı Formation. These veins contain mainly barite (80-85%) and galena (10-15%), and lesser amounts of sphalerite, pyrite, fahlore, limonite, quartz and calcite as gangue minerals. Barite developed during an early episode of mineralisation and was mylonitised before the precipitation of …


Short-Term Evolution Of A Marsh Island System And The Importance Of Cold Front Forcing, Terrebonne Bay, Louisiana, Dana Ann Watzke Jan 2004

Short-Term Evolution Of A Marsh Island System And The Importance Of Cold Front Forcing, Terrebonne Bay, Louisiana, Dana Ann Watzke

LSU Master's Theses

Short-term, wave induced erosion along bay beaches in the northern Gulf of Mexico has been linked to the postfrontal phase of cold front passages. Not until recently has consideration been given to the importance of wave erosion on marshes fringing large bays during the entire cold front event. Two WAVCIS (Wave-Current-Surge-Information System) stations were established on the north and south flank of a small marsh island in Terrebonne Bay, Louisiana, to measure and elucidate the hydrodynamic response to these events. Data from WAVCIS stations, which includes wind speed and direction, air temperature, significant wave height and water level, were collected …


Saguaro National Park Case Study, Douglas S. Kenney, Doug Cannon, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Saguaro National Park Case Study, Douglas S. Kenney, Doug Cannon, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

25, A-5 p. : ill., maps


Private Lands Conservation In The Bahamas, Elizabeth Mccormack, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Private Lands Conservation In The Bahamas, Elizabeth Mccormack, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

59 p. ; 28 cm


Private Lands Conservation In Grenada, Kevin Doran, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Private Lands Conservation In Grenada, Kevin Doran, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

47 p. ; 28 cm


Private Lands Conservation In The Federated States Of Micronesia, Kevin Doran, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Private Lands Conservation In The Federated States Of Micronesia, Kevin Doran, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

74 p. ; 28 cm


Private Lands Conservation In Palau, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Private Lands Conservation In Palau, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

1, 37 leaves ; 28 cm


Private Lands Conservation In Guam, Craig Corona, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Private Lands Conservation In Guam, Craig Corona, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

93 p. ; 28 cm


Private Lands Conservation In The Solomon Islands, Craig Corona, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Private Lands Conservation In The Solomon Islands, Craig Corona, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

69 p. ; 28 cm


Tuning Polymeric Chiral Surfactants For Enhanced Enantiomeric Recognition In Micellar Electrokinetic Chromatography, Jepkoech Tarus Jan 2004

Tuning Polymeric Chiral Surfactants For Enhanced Enantiomeric Recognition In Micellar Electrokinetic Chromatography, Jepkoech Tarus

LSU Doctoral Dissertations

The research presented in this dissertation involves the synthesis, modification, characterization, and the application of polymeric surfactants in micellar electrokinetic chromatography (MEKC). Sodium undecenoyl-L-Leucinate (L-SUL) was synthesized and modified by use of alkali metal counterions, alcohols, and Triton X-102. Characterization of the modified poly-L-SUL was performed in order to elucidate the structural changes on the surfactants by use of four techniques. While surface tensiometry was used for the determination of the critical micelle concentration (cmc), fluorescence measurements were used for the determination of the polarity of the modified polymeric surfactants. The information about the size of the polymeric surfactants was …


Spectroscopic Investigation Of Nitrogenase: Epr And Mcd Studies Of The Femo Cofactor And The P-Cluster, Robyn B. Broach Jan 2004

Spectroscopic Investigation Of Nitrogenase: Epr And Mcd Studies Of The Femo Cofactor And The P-Cluster, Robyn B. Broach

LSU Doctoral Dissertations

Little is known about substrate binding and reduction of nitrogenase. EPR spectroscopy is used here to observe intermediate states generated by different substrates. Two different spin states (S=3/2 and S=1/2) were exhibited for each substrate, which may result from different binding of the substrate to the cofactor (side-on or terminal binding) or the difference of the substrate binding to either Fe or Mo of the cofactor. Parallel studies were performed on a variant MoFe protein, alpha-195Gln, which exhibited different signals from the wild-type suggesting that the substituted amino acid maybe necessary to reach some mechanistic states that the …


The Distribution Of Radon Concentration In Caves, Arrigo A. Cigna Jan 2004

The Distribution Of Radon Concentration In Caves, Arrigo A. Cigna

International Journal of Speleology

Radon concentration in caves is known to vary within an extremely wide range. Here the distribution of the average values of radon concentration is examined and a power law describing is identified, i.e. radon concentration has a fractal dimension D=1.26. This fact means that concentrations are not grouped around a mean value, a characteristic common to many other phenomena.


Protein Aggregation Studies: Inhibiting And Encouraging Β-Amyloid Aggregation, Jed Paul Aucoin Jan 2004

Protein Aggregation Studies: Inhibiting And Encouraging Β-Amyloid Aggregation, Jed Paul Aucoin

LSU Doctoral Dissertations

This work demonstrates peptide-based aggregation mediation of fibril forming peptides, notably β-amyloid (1-40), Aβ1-40. To achieve the goals of this work, Aβ1-40 aggregation was governed by ionic strength, temperature, and pH. After controlling and reproducing Aβ1-40 aggregate formation (fibrils), each peptide-based aggregation mediator was evaluated for its ability to self-aggregate and to possess surface-active properties. The incorporation of these mediators in Aβ1-40 solutions changed the surface tension and produced aggregate complexes of mediator and Aβ1-40. Evidence that Aβ1-40 fibril formation may be mediated by disorder-to-order transitions has been observed by layer formation …


Correction To "Breaking Of Thunderstorm-Generated Gravity Waves As A Source Of Short-Period Ducted Waves At Mesopause Altitudes", Jonathan B. Snively, Victor P. Pasko Jan 2004

Correction To "Breaking Of Thunderstorm-Generated Gravity Waves As A Source Of Short-Period Ducted Waves At Mesopause Altitudes", Jonathan B. Snively, Victor P. Pasko

Publications

No abstract provided.


Analysis Of A Multigrid Algorithm For Time Harmonic Maxwell Equations, Jay Gopalakrishnan, Joseph E. Pasciak, Leszek Demkowicz Jan 2004

Analysis Of A Multigrid Algorithm For Time Harmonic Maxwell Equations, Jay Gopalakrishnan, Joseph E. Pasciak, Leszek Demkowicz

Mathematics and Statistics Faculty Publications and Presentations

This paper considers a multigrid algorithm suitable for efficient solution of indefinite linear systems arising from finite element discretization of time harmonic Maxwell equations. In particular, a "backslash" multigrid cycle is proven to converge at rates independent of refinement level if certain indefinite block smoothers are used. The method of analysis involves comparing the multigrid error reduction operator with that of a related positive definite multigrid operator. This idea has previously been used in multigrid analysis of indefinite second order elliptic problems. However, the Maxwell application involves a nonelliptic indefinite operator. With the help of a few new estimates, the …


A Characterization Of Hybridized Mixed Methods For Second Order Elliptic Problems, Bernardo Cockburn, Jay Gopalakrishnan Jan 2004

A Characterization Of Hybridized Mixed Methods For Second Order Elliptic Problems, Bernardo Cockburn, Jay Gopalakrishnan

Mathematics and Statistics Faculty Publications and Presentations

In this paper, we give a new characterization of the approximate solution given by hybridized mixed methods for second order self-adjoint elliptic problems. We apply this characterization to obtain an explicit formula for the entries of the matrix equation for the Lagrange multiplier unknowns resulting from hybridization. We also obtain necessary and sufficient conditions under which the multipliers of the Raviart–Thomas and the Brezzi–Douglas–Marini methods of similar order are identical.


Decentralized Control Of Vehicle Formations, Gerardo Lafferriere, Anca Williams, John S. Caughman Iv, J. J. P. Veerman Jan 2004

Decentralized Control Of Vehicle Formations, Gerardo Lafferriere, Anca Williams, John S. Caughman Iv, J. J. P. Veerman

Mathematics and Statistics Faculty Publications and Presentations

This paper investigates a method for decentralized stabilization of vehicle formations using techniques from algebraic graph theory. The vehicles exchange information according to a pre-specified communication digraph, G. A feedback control is designed using relative information between a vehicle and its in-neighbors in G. We prove that a necessary and sufficient condition for an appropriate decentralized linear stabilizing feedback to exist is that G has a rooted directed spanning tree. We show the direct relationship between the rate of convergence to formation and the eigenvalues of the (directed) Laplacian of G. Various special situations are discussed, including …


Eminent Domain: B.L. Wiggins, Forestry, And The New South At Sewanee, Char Miller Jan 2004

Eminent Domain: B.L. Wiggins, Forestry, And The New South At Sewanee, Char Miller

Pomona Faculty Publications and Research

The history of the University of the South and of its forest is intertwined. The health of the forest—and of the university—hung in the balance when Benjamin Wiggins took charge of both in 1893.


Evaluation Of Multiple Models To Distinguish Closely Related Forms Of Disease Using Dna Microarray Data: An Application To Multiple Myeloma, Johanna S. Hardin, Michael Waddell, C. David Page, Fenghuang Zhan, Bart Barlogie, John Shaughnessy, John J. Crowley Jan 2004

Evaluation Of Multiple Models To Distinguish Closely Related Forms Of Disease Using Dna Microarray Data: An Application To Multiple Myeloma, Johanna S. Hardin, Michael Waddell, C. David Page, Fenghuang Zhan, Bart Barlogie, John Shaughnessy, John J. Crowley

Pomona Faculty Publications and Research

Motivation: Standard laboratory classification of the plasma cell dyscrasia monoclonal gammopathy of undetermined significance (MGUS) and the overt plasma cell neoplasm multiple myeloma (MM) is quite accurate, yet, for the most part, biologically uninformative. Most, if not all, cancers are caused by inherited or acquired genetic mutations that manifest themselves in altered gene expression patterns in the clonally related cancer cells. Microarray technology allows for qualitative and quantitative measurements of the expression levels of thousands of genes simultaneously, and it has now been used both to classify cancers that are morphologically indistinguishable and to predict response to therapy. It is …


Infrared Thermal Imaging Of Automobiles: Identification Of Cold Start Vehicles, Angela M. Monateri, Donald H. Stedman Jan 2004

Infrared Thermal Imaging Of Automobiles: Identification Of Cold Start Vehicles, Angela M. Monateri, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

No abstract provided.


Halitpaşa Transpressive Zone: Implications For An Early Pliocene Compressional Phase In Central Western Anatolia, Turkey, Orhan Kaya, Engi̇n Ünay, Gerçek Saraç, Silke Eichhorn, Sabine Hassenrück, Andrea Knappe, Asaf Pekdeğer, Serdar Mayda Jan 2004

Halitpaşa Transpressive Zone: Implications For An Early Pliocene Compressional Phase In Central Western Anatolia, Turkey, Orhan Kaya, Engi̇n Ünay, Gerçek Saraç, Silke Eichhorn, Sabine Hassenrück, Andrea Knappe, Asaf Pekdeğer, Serdar Mayda

Turkish Journal of Earth Sciences

The Late Cenozoic evolution of the eastern Aegean is dominated by widespread continental extension. The most prominent structures are E-W- and NE-SW-trending grabens and intervening horsts, while NW-SE- and N-S-trending faults form the other less important structures. This paper documents the results of recent geological mapping and structural and stratigraphical analysis from the Halitpaşa half graben, which forms the northwestern continuation of the Gediz Graben. Field evidence for a new NW-SE-trending dextral wrench-dominated fault zone (here named the Halitpaşa transpression zone), which involved the thrusting of pre-Palaeogene basement onto Upper Miocene-Lower Pliocene sediments, is presented. The fault zone is correlated …