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Chemistry

2005

Series

Articles 1 - 12 of 12

Full-Text Articles in Physical Sciences and Mathematics

Kondo Resonances And Anomalous Gate Dependence In The Electrical Conductivity Of Single-Molecule Transistors, L H. Yu, Z K. Keane, Jacob W. Ciszek, L Cheng, J M. Tour, T Baruah, M R. Pederson, D Natelson Dec 2005

Kondo Resonances And Anomalous Gate Dependence In The Electrical Conductivity Of Single-Molecule Transistors, L H. Yu, Z K. Keane, Jacob W. Ciszek, L Cheng, J M. Tour, T Baruah, M R. Pederson, D Natelson

Chemistry: Faculty Publications and Other Works

We report Kondo resonances in the conduction of single-molecule transistors based on transition metal coordination complexes. We find Kondo temperatures in excess of 50 K, comparable to those in purely metallic systems. The observed gate dependence of the Kondo temperature is inconsistent with observations in semiconductor quantum dots and a simple single-dot-level model. We discuss possible explanations of this effect, in light of electronic structure calculations.

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Principal Component Analysis For Predicting Transcription-Factor Binding Motifs From Array-Derived Data, Yunlong Liu, Matthew P Vincenti, Hiroki Yokota Nov 2005

Principal Component Analysis For Predicting Transcription-Factor Binding Motifs From Array-Derived Data, Yunlong Liu, Matthew P Vincenti, Hiroki Yokota

Dartmouth Scholarship

The responses to interleukin 1 (IL-1) in human chondrocytes constitute a complex regulatory mechanism, where multiple transcription factors interact combinatorially to transcription-factor binding motifs (TFBMs). In order to select a critical set of TFBMs from genomic DNA information and an array-derived data, an efficient algorithm to solve a combinatorial optimization problem is required. Although computational approaches based on evolutionary algorithms are commonly employed, an analytical algorithm would be useful to predict TFBMs at nearly no computational cost and evaluate varying modelling conditions. Singular value decomposition (SVD) is a powerful method to derive primary components of a given matrix. Applying SVD …

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Inhibition Of Cellular Respiration By Doxorubicin, Zhimin Tao, Henry G. Withers, Harvey S. Penefsky, Jerry Goodisman, Abdul Kader Souid Nov 2005

Inhibition Of Cellular Respiration By Doxorubicin, Zhimin Tao, Henry G. Withers, Harvey S. Penefsky, Jerry Goodisman, Abdul Kader Souid

Chemistry - All Scholarship

Doxorubicin executes apoptosis, a process known to produce leakage of cytochrome c and opening of the mitochondrial permeability transition pores. To define the loss of mitochondrial function by apoptosis, we monitored cellular respiration during continuous exposure to doxorubicin. A phosphorescence analyzer capable of stable measurements over at least 5 h was used to measure [O(2)]. In solutions containing glucose and cells, [O(2)] declined linearly with time, showing that the kinetics of oxygen consumption was zero order. Complete inhibition of oxygen consumption by cyanide indicated that oxidations occurred in the respiratory chain. A decline in the rate of respiration was evident …

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Semiclassical Nonadiabatic Dynamics Using A Mixed Wave-Function Representation, Sophya Garashchuk, Vitaly A. Rassolov, George C. Schatz Nov 2005

Semiclassical Nonadiabatic Dynamics Using A Mixed Wave-Function Representation, Sophya Garashchuk, Vitaly A. Rassolov, George C. Schatz

Faculty Publications

Nonadiabatic effects in quantum dynamics are described using a mixed polar/coordinate space representation of the wave function. The polar part evolves on dynamically determined potential surfaces that have diabatic and adiabatic potentials as limiting cases of weak localized and strong extended diabatic couplings. The coordinate space part, generalized to a matrix form, describes transitions between the surfaces. Choice of the effective potentials for the polar part and partitioning of the wave function enables one to represent the total wave function in terms of smooth components that can be accurately propagated semiclassically using the approximate quantum potential and small basis sets. …

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Catena-Poly[[Bis(Α-Thenoyltrifluoroacetonato)Copper(Ii)]-Μ-1,4-Di-4-Pyridyl-2,3-Diazabuta-1,3-Diene], William J. Perkins, Tamara Maxwell, Mark D. Smith, Leroy Peterson Jr., Hans-Conrad Zur Loye Sep 2005

Catena-Poly[[Bis(Α-Thenoyltrifluoroacetonato)Copper(Ii)]-Μ-1,4-Di-4-Pyridyl-2,3-Diazabuta-1,3-Diene], William J. Perkins, Tamara Maxwell, Mark D. Smith, Leroy Peterson Jr., Hans-Conrad Zur Loye

Faculty Publications

In the one-dimensional title polymer, [Cu(C8H4F3O2S)2(C12H10N4)]n or [Cu(L)2(tta)2] [tta is -thenoyltrifluoroacetonato and L is 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene], Cu2+ lies on a center of inversion. It is axially coordinated by two pyridyl N atoms from two different L ligands and equatorially coordinated by four O atoms from two chelating tta ligands. The ligand L propagates the one-dimensional chain structure by serving as a bridging ligand between two Cu octahedra via Cu-N coordinate bonds.

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Activation Of Carboplatin By Carbonate, Anthony J. Di Pasqua, Jerry Goodisman, Deborah J. Kerwood, Bonnie B. Toms, James C. Dabrowiak Sep 2005

Activation Of Carboplatin By Carbonate, Anthony J. Di Pasqua, Jerry Goodisman, Deborah J. Kerwood, Bonnie B. Toms, James C. Dabrowiak

Chemistry - All Scholarship

Carboplatin, [Pt(NH3)2(CBDCA-O,O')], 1, where CBDCA is cyclobutane-1,1-dicarboxylate, is in wide clinical use for the treatment of ovarian, lung, and other types of cancer. Because carboplatin is relatively unreactive toward nucleophiles, an important question concerning the drug is the mechanism by which it is activated in vivo. Using [1H,15N] heteronuclear single quantum coherance spectroscopy (HSQC) NMR and 15N-labeled carboplatin, we show that carboplatin reacts with carbonate ion in carbonate buffer to produce ring-opened products, the nature of which depends on the pH of the medium. The assignment of HSQC NMR resonances was facilitated by studying the reaction of carboplatin in strong …

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Tris(1,10-Phenanthroline)Cobalt(Ii) Triiodide, Meredith A. Tershany, Andrea M. Goforth, Mark D. Smith, Leroy Peterson Jr., Hans-Conrad Zur Loye Aug 2005

Tris(1,10-Phenanthroline)Cobalt(Ii) Triiodide, Meredith A. Tershany, Andrea M. Goforth, Mark D. Smith, Leroy Peterson Jr., Hans-Conrad Zur Loye

Faculty Publications

The asymmetric unit of the title compound, [Co(C12H8N2)3](I3)2, contains one [Co(1,10-phenanthroline)3]2+ cation, half each of two centrosymmetric triiodide anions, and one complete triiodide anion. The title compound was synthesized solvothermally from Co(NO3)2, 1,10-phenanthroline, and SnI2, where the SnI2 reagent serves only as a source of I atoms.

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Tris(Ethylenediamine)Cobalt(Iii) Nonaiododibismuthate, Andrea M. Goforth, Rachael E. Hipp, Mark D. Smith, Leroy Peterson Jr., Hans-Conrad Zur Loye Jul 2005

Tris(Ethylenediamine)Cobalt(Iii) Nonaiododibismuthate, Andrea M. Goforth, Rachael E. Hipp, Mark D. Smith, Leroy Peterson Jr., Hans-Conrad Zur Loye

Faculty Publications

The asymmetric unit of the title compound, [Co(C2H8N2)3][Bi2I9], crystallizes in the orthorhombic space group Cmc21. The asymmetric unit contains half of a [Co(en)3]3+ cation (en is ethylenediamine) and half of a [Bi2I9]3- anion. Both species are located on mirror planes, requiring the [Co(en)3]3+ cation to be present as a statistically disordered mixture of both enantiomeric forms. Crystals were grown solvothermally from an ethanol-water solvent mixture using rac-[Co(en)3]I3 and bismuth triiodide …

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Promoting Learning Through Peer Group Work, Christine O'Connor, Renli Ma Jul 2005

Promoting Learning Through Peer Group Work, Christine O'Connor, Renli Ma

Conference Papers

The session aimed to help the Summer School participants develop tasks and assessment strategies of peer group work in their own teaching.

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Cisplatin Carbonato Complexes. Implications For Uptake, Antitumor Properties, And Toxicity, Corey R. Centerwall, Jerry Goodisman, Deborah J. Kerwood, James C. Dabrowiak May 2005

Cisplatin Carbonato Complexes. Implications For Uptake, Antitumor Properties, And Toxicity, Corey R. Centerwall, Jerry Goodisman, Deborah J. Kerwood, James C. Dabrowiak

Chemistry - All Scholarship

The reaction of aquated cisplatin with carbonate which is present in culture media and blood is described. The first formed complex is a monochloro monocarbonato species, which upon continued exposure to carbonate slowly forms a biscarbonato complex. The formation of carbonato species under conditions that simulate therapy may have important implications for uptake, antitumor properties, and toxicity of cisplatin.

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Crystal Structure Of The Gtpase Domain Of Rat Dynamin 1, Thomas F. Reubold, Susanne Eschenburg, Andreas Becker, Marilyn Leonard, Sandra L. Schmid, Richard B. Vallee, F. Jon Kull, Dietmar J. Manstein Jan 2005

Crystal Structure Of The Gtpase Domain Of Rat Dynamin 1, Thomas F. Reubold, Susanne Eschenburg, Andreas Becker, Marilyn Leonard, Sandra L. Schmid, Richard B. Vallee, F. Jon Kull, Dietmar J. Manstein

Dartmouth Scholarship

Here, we present the 1.9-A crystal structure of the nucleotide-free GTPase domain of dynamin 1 from Rattus norvegicus. The structure corresponds to an extended form of the canonical GTPase fold observed in Ras proteins. Both nucleotide-binding switch motifs are well resolved, adopting conformations that closely resemble a GTP-bound state not previously observed for nucleotide-free GTPases. Two highly conserved arginines, Arg-66 and Arg-67, greatly restrict the mobility of switch I and are ideally positioned to relay information about the nucleotide state to other parts of the protein. Our results support a model in which switch I residue Arg-59 gates GTP binding …

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Simulations Of Nanopore Formation And Phosphatidylserine Externalization In Lipid Membranes Subjected To A High-Intensity, Ultrashort Electric Pulse, Q. Hu, R. P. Joshi, K. H. Schoenbach Jan 2005

Simulations Of Nanopore Formation And Phosphatidylserine Externalization In Lipid Membranes Subjected To A High-Intensity, Ultrashort Electric Pulse, Q. Hu, R. P. Joshi, K. H. Schoenbach

Bioelectrics Publications

A combined MD simulator and time dependent Laplace solver are used to analyze the electrically driven phosphatidylserine externalization process in cells. Time dependent details of nanopore formation at cell membranes in response to a high-intensity (100kV∕cm), ultrashort (10ns) electric pulse are also probed. Our results show that nanosized pores could typically be formed within about 5ns. These predictions are in very good agreement with recent experimental data. It is also demonstrated that defect formation and PS externalization in membranes should begin on the anode side. Finally, the simulations confirm that PS externalization is a nanopore facilitated event, rather than the …

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