Physical Sciences and Mathematics Commons^™

The Voltammetry Of Sc3@C82, Mark Anderson, Harry Dorn, Paul Burbank, Steven Stevenson, James Gibson

Mark R. Anderson

Many endohedral metallofullerenes have a C82 cage surrounding the metals, even though the normal arc-vaporization method of fullerene preparation does not generate C82 in significant abundance.1-10Manolopous et al.11-13attribute the low abundance of empty-cage C82 to the unfavorable electron configuration of this species. Consequently, the prevalence of C82 in metallofullerenes may be the result of an electron transfer from the encapsulated metal atoms to the fullerene cage.10-13 The extent of this charge transfer also contributes to the properties (e.g. catalytic, superconductive, nonlinear optical, and ferromagnetic) that are attributed to the endohedral metallofullerenes.14,15Because of the importance of the charge transfer reaction, characterization …

Constraint Satisfaction Methods For Generating Valid Cuts, John Hooker

John Hooker

No abstract provided.

A Niobium(V) Complex With Mixed O,S-Donor Ligands. Synthesis, Structure And Properties Of The Anion Tris(2-Mercapto-4-Methylphenolato)Niobate(V), Paul Challen, Diane Peapus, Karen Magnes

Paul R. Challen

Reaction of Nb(OEt)5 with 2-mercapto-4-methylphenol (mmpH2) in the presence of triethylamine gave the mononuclear tris complex (Et3NH)[Nb(mmp)3] which was structurally characterized. The coordination geometry around the niobium is between octahedral and trigonal prismatic, with a twist angle of 41.5°. The mercaptophenolate ligands are arranged around the metal in a “propeller” fashion. (Et3NH)[Nb(mmp)3] was characterized by IR, 1H NMR and UV-vis spectroscopies, and cyclic voltammetry. A reversible reduction wave found at −1.03 V is for reduction to the NbIV complex.

Effectiveness Of The Protected Area Network In Biodiversity Conservation: A Case-Study Of Meghalaya State, M. Latif Khan, Shaily Menon, Kamaljit Bawa

Shaily Menon

The North-Eastern region of India is significant for biodiversity conservation because of its floristic richness and high levels of endemism. Deforestation levels are high in the region due to anthropogenic pressures. We accessed various literature sources to create a database for Meghalaya state containing information on plant species, habit, altitudinal distribution, endemism, and endangered status. Information on the existing protected area network (type, extent, and altitudinal representation) was added to the database. The database was used to assess the effectiveness of the existing protected area network in conserving the floristic biodiversity of the state. Of a total of 3331 plant …

Biodiversity Monitoring: The Missing Ingredient, Kamaljit Bawa, Shaily Menon

Shaily Menon

With mounting losses in biological diversity, inventorying and monitoring of biodiversity to assess the magnitude and rate of losses are emerging as dominant themes in conservation biology. Inventorying has been defined as the surveying, sorting, cataloging, quantifying and mapping of entities ranging from genes to landscapes1 and monitoring has been defined as the surveillance of the compliance with or deviation from a predetermined standard2. Renner and Ricklefs3 argued that rushed inventories will compromise scientific rigor and have little influence on decision making. More recently, Stork et al.4 argued that losses in biological diversity are so severe that inventorying and monitoring …

The Elastic Moduli Of Random Networks: Calculations, Anthony Day

Anthony Roy Day

No abstract provided.

Mathematica In Action., Stan Wagon

Stan Wagon, Retired

No abstract provided.

Constructing Essential Laminations In 2-Bridge Knot Surgered 3-Manifolds, Ramin Naimi

Ramin Naimi

A nontrivial knot that can be drawn with only two relative maxima in the vertical direction is called a 2-bridge knot, and one that can be drawn on a torus is called a torus knot. Loosely speaking, a lamination in a manifold M is a foliation of M, except that it can have a nonempty open complement in M, and very loosely speaking, the lamination is essential if each leaf of it L is incompressible, i.e. inclusion of L into M induces an injective homomorphism from π1(L) into π1(M). Our main result is: Theorem 2. Every 3-manifold obtained by surgery …

Is There Environmental Racism? The Demographics Of Hazardous Waste In Los Angeles County, J. Boer, Manuel Pastor, James Sadd, Lori Snyder

James Sadd

The article assesses the location of treatment, storage and disposal facilities (TSDF) in Los Angeles County, California, with focus on racism. The study shows that a simple comparison of tracts with and without TSDF reveals statistically significant differences by race and economic status along the lines suggested by the environmental justice proponents. There are also significant differences by industrial land use and manufacturing employment along the lines suggested by critics of the environmental justice concept. In this multivariate model race, along with industrial land use and employment in manufacturing, remains a factor, rising income that has a positive then a …

Electrochemistry Of C82: Relationship To Metallofullerene Electrochemistry, Paul Burbank, James Gibson, Harry Dorn, Mark Anderson

Mark R. Anderson

Square-wave voltammetry of C82 in pyridine solutions containing 0.10 M tetra-n-butyl ammonium perchlorate indicates that C82 is reduced in four one-electron steps prior to the onset of electrolyte decomposition. The first reduction occurs at potentials positive of the reported first reduction potentials of other empty cage fullerenes, and at approximately the same reported potential for the first reduction of the endohedral metallofullerenes La@C82 and Y@C82. No oxidations were observed for the C82 under these conditions.

Purification And Crystallization Of Cyclin-Dependent Kinase Inhibitor P21., D. Mayrose, Michael Nichols, Y. Xiong, H. Ke

Michael A Nichols

p21, a universal inhibitor of mammalian cyclin-dependent kinases (CDK), regulates cell cycle progression by forming various distinct protein complexes with cyclins, CDKs, and the proliferating cell nuclear antigen. We have overexpressed recombinant human p21 in E. coli and purified active p21 to near homogeneity on a large scale. Crystals of recombinant p21 have been grown in the space group P2(1) a = 157.4, b = 152.7, c = 90.6 A, and beta = 92.7 degrees. The diffraction data of the recombinant p21 have been collected to 2.5 and 3.5 A resolution for the native crystal and two heavy atom derivatives …

A High School-Collegiate Outreach Program In Chemistry And Biology Delivering Modern Technology In A Mobile Van, Chris Craney, April Mazzeo, Kaye Lord

Chris L. Craney

The "Teachers plus Occidental equals Partnership in Science" van program in Los Angeles CA was launched in June 1992. The program's goal is to improve high school biology and chemistry students' laboratory instruction by enhancing their teachers' knowledge and classroom application of modern instruments, techniques and experiments.

Direct Dating Of Deformation; U-Pb Age Of Syndeformational Sphene Growth In The Proterozoic Laramie Peak Shear Zone, Phillip G. Resor, Kevin R. Chamberlain, Carol D. Frost, B Ronald Frost, Arthur W. Snoke

Phillip G Resor

In this paper, we show that deformation can be dated by combining mesoscopic and microscopic structural observations with an understanding of metamorphic mineral reactions and U-Pb ages of newly grown sphene (titanite). This approach can be used on a variety of rock types that have been deformed at a wide range of metamorphic conditions. In an example from the Proterozoic Laramie Peak shear zone of southeastern Wyoming, a single period of syntectonic sphene growth in sheared mafic dikes is documented both by a strong spatial relationship between deformation and metamorphism and by sphene microtextures. U-Pb analyses of sphene separates give …

The Spectral Function Of Random Resistor Networks, Anthony Day, M. Thorpe

Anthony Roy Day

The effective complex conductivity [...] of a two-component material can be conveniently expressed as an integral transformation of a spectral function. The spectral function depends only on the geometry of the material, and can be used to calculate [...] for any particular choice of component conductivities. This is a very useful feature if the component conductivities can be varied (by changing the temperature or frequency, for example) at a fixed geometry. We present a derivation of the spectral function that identifies it as a density of states. We have made direct numerical calculations of the spectral function of two-dimensional random …

Influence Of Solvent On The Interfacial Structure Of Self-Assembled Alkanethiol Monolayers, Mark Anderson, Mark Evaniak, Minhui Zhang

Mark R. Anderson

Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) is used to study the structure of octadecanethiol, tetradecanethiol, and decanethiol monolayers in the presence of air, deuterium oxide, and acetonitrile-d3. It is found that the structure of the monolayer is dependent on both the adjacent environment and the initial structural order of the monolayer. In the D2O solutions, spectral changes are similar for the three monolayers and are characteristic of interaction predominantly between the solvent and the terminal portion of the monolayers. This correlates with electrochemical capacitance measurements that indicate little permeation of the aqueous electrolyte in the monolayer, even with the …

Development And Evaluation Of Internet-Based Hypermedia Chemistry Tutorials, Brian Tissue, Ronald Earp, Ching-Wan Yip, Mark Anderson

Mark R. Anderson

This progress report describes the development and student use of World-Wide-Web-based prelaboratory exercises in senior-level Instrumental Analysis during the 1995 Fall semester. The laboratory preparation exercises contained hypermedia tutorials and multiple-choice questions that were intended to familiarize the students with the experiments and instrumentation before their laboratory session. The overall goal of our work is to explore ways in which computer and network technology can be applied in education to improve the cost-effectiveness and efficacy of teaching. The course material can be accessed at http://www.chem.vt.edu/chem-ed/4114/Fall1995.html.

Scanning Local‐Acceleration Microscopy, Nancy Burnham, A. Kulik, G. Gremaud, P. Gallo, F. Oulevey

Nancy A. Burnham

By adapting a scanning force microscope to operate at frequencies above the highest tip–sample resonance, the sensitivity of the microscope to materials’ properties is greatly enhanced. The cantilever’s behavior in response to high‐frequency excitation from a transducer underneath the sample is fundamentally different than to its low‐frequency response. In this article, the motivations, instrumentation, theory, and first results for this technique are described.

Materials’ Properties Measurements: Choosing The Optimal Scanning Probe Microscope Configuration, Nancy Burnham, G Gremaud, A Kulik, P Gallo, F Oulevey

Nancy A. Burnham

Rheological models are used to represent different scanning probe microscope configurations. The solutions for their static and dynamic behavior are found and used to analyze which scanning probe microscope configuration is best for a given application. We find that modulating the sample at high frequencies results in the best microscope behavior for measuring the stiffness of rigid materials, and that by modulating the tip at low frequencies and detecting the motion of the tip itself (not its position relative to the tip holder) should be best for studying compliant materials in liquids.

Vanadium(Iv) Complexes With Mixed O,S Donor Ligands. Syntheses, Structures, And Properties Of The Anions Tris(2-Mercapto-4-Methylphenolato)Vanadate(Iv) And Bis(2-Mercaptophenolato)Oxovanadate(Iv), Paul Klich, Andrew Daniher, Paul Challen, David Mcconville, Wiley Youngs

Paul R. Challen

Reaction of VO(acac)2 with 2-mercaptophenol (mpH2) in the presence of triethylamine gives the mononuclear tris complex (Et3NH)2[V(mp)3] (1), in which the vanadyl oxygen has been displaced. An analogous reaction using 2-mercapto-4-methylphenol (mmpH2) afforded (Et3NH)(PNP)[V(mmp)3] (2), which was structurally characterized. 2 crystallizes in the orthorhombic space group Pna21 with unit cell parameters (at −163 °C) a = 23.974(7) Å, b = 9.569(4) Å, c = 25.101(6) Å, and Z = 4. The coordination geometry around the vanadium is between octahedral and trigonal prismatic. Reaction of VO(acac)2 with the sodium salt of 2-mercaptophenol produces the vanadyl(IV) complex Na(Ph4P)[VO(mp)2]·Et2O (3), which crystallizes in …

Lion-Tailed Macaques (Macaca Silenus) In A Disturbed Forest Fragment: Activity Patterns And Time Budget, Shaily Menon, Frank Poirier

Shaily Menon

We describe the activity patterns and time budget of a feral group of lion-tailed macaques that were confined to a disturbed forest fragment of 65 ha and compare the results with those obtained for groups in protected forests. The degraded nature of the study site was reflected in low tree densities, low specific diversity, gaps in the girth distribution of trees, and frequent disturbance by humans. The study group of 43 subjects was twice as large as lion-tailed macaque groups in protected habitats. They spent the most time ranging (34.0%), followed by foraging (23.7%), feeding (17.9%), resting (16.0%), and other …

Animating Calculus: Mathematica Notebooks For The Laboratory, E. Packel, Stan Wagon

Stan Wagon, Retired

No abstract provided.

The In Situ Passive Acoustic Measurement Of Shingle Movement Under Waves And Currents: Instrument (Tosca) Development And Preliminary Results, George Voulgaris, Michael Wilkin, Michael Collins

George Voulgaris

An instrumented platform (TOSCA) is described for monitoring coarse-grained sediment transport in high (wave and tidal) energy environments. The system consists of a number of sensors which measure: instantaneous current velocities at three levels; sea surface elevation; and self-generated noise (SGN) caused by intercollision of particles in transit. SGN is related to transport rates, on the basis of laboratory calibration; this, in turn, allows a correlation with simultaneous near-bed shear stress to be established. During the field measurements, PC-based real-time data transmission is realised through the use of a (buoyed) radio telemetry system.

TOSCA has been deployed in eastern Christchurch …

Nanosubharmonics: The Dynamics Of Small Nonlinear Contacts, Nancy Burnham, A Kulik, G Gremaud, Gad Briggs

Nancy A. Burnham

We observed the generation of subharmonics and chaos in a nanometer-sized mechanical contact. To first order, the behavior matches that of macroscopic systems, with some intriguing secondary differences. As the occurrence of periodic behavior (subharmonics) is related to the coefficient of restitution, it may be possible to image local energy dissipation with nanometer resolution.

Categories Of Fuzzy Sets With Values In A Quantale Or Projectale, Lawrence Stout

Lawrence N. Stout

Properties of the lattice L are reflected in the properties of the categories Set(L), Set(L)/(A,α), and the lattice U(A, α). The lattices U(A,α) best reflect the structures on the lattice if the structure is inherited by closed down segments and direct products. Operations at the level of the slice categories require distributivity too. The first object of this paper is to see how the additional structures given by an associative operation & which distributes over sups and hence has a right adjoint (a quantale in the sense of Rosenthal [7]) shows up at the three different levels for fuzzy sets. …

Asymptotic Behavior Of Solutions Of Asymptotically Constant Coefficient System Of Linear Differential Equations, William F. Trench

William F. Trench

No abstract provided.

Investigation Of The Charge Transfer Properties Of Electrodes Modified By The Spontaneous Adsorption Of Unsymmetrical Dialkyl Sulfides, Minhui Zhang, Mark Anderson

Mark R. Anderson

Electrodes modified by the spontaneous adsorption of unsymmetrical dialkyl sulfides are used to investigate two monolayer properties, structural disorder and solvent compatibility, that may be of importance in determining the ability for faradaic charge transport to occur in the presence of the monolayer. Two groups of dialkyl sulfides are prepared and studied: a purely hydrocarbon dialkyl sulfide with the structure CH3(CH2)17S(CH2)nCH3, where n, = 7,9, and 17, and an acid containing dialkyl sulfide with the structure CH3(CH2)17S(CH2)mCOOH, where m = 7, 10, and 15. Reflection infrared spectroscopy of the hydrocarbon dialkyl sulfide reveals that the monolayer structure is disordered, when …

Effect Of Applied Potential Upon The In Situ Structure Of Self-Assembled Monolayers On Gold Electrodes, Mark Anderson, Marilyn Gatin

Mark R. Anderson

Polarization modulation Fourier transform infrared reflection absorption spectroscopy (PM-FTIRRAS) has been utilized to study the in situ structure of octadecanethiol when adsorbed to gold electrode surfaces and with the application of potential to the substrate. It is found that applied potential has little effect upon the spectrum of the monolayer in the presence of D2O solutions containing 0.10 M NaClO4. The presence of an acetonitrile solution contacting the monolayer leads to small changes in the infrared spectrum relative to that seen in D2O solutions, suggestive of some small disordering of the monolayer caused by the presence of the acetonitrile. With …

Application Of The Quartz Crystal Microbalance To Characterize The Interaction Of Solutes With Modified Interfaces, John Roush, David Thacker, Mark Anderson

Mark R. Anderson

Piezoelectric quartz crystals, modified by the spontaneous adsorption of either 4-aminothiophenol or octadecanethiol, were utilized to investigate the selective interactions that exist between solutes and the surface modification layer. It is found that the exposed amine functionality of the 4-aminothiophenol monolayer increases the sensitivity of the quartz crystal microbalance to phenols relative to the response found at either a crystal modified with an octadecanethiol monolayer or an unmodified quartz crystal. Protonation of the amino group decreases the sensitivity of the 4-aminothiophenol modified crystal toward the phenol solutes, to a level approximately the same as seen for the octadecanethiol monolayer and …

6li And 15n Nuclear Magnetic Resonance Studies Of Mixed Alkali Metal Cation Hexamethyldisilazide Bases, Michael Nichols, Delia Waldmüller, Paul Williard

Michael A Nichols

No abstract provided.

The Power Of Visualization: Notes From A Mathematica Course, Stan Wagon

Stan Wagon, Retired

No abstract provided.