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Articles 121 - 150 of 154
Full-Text Articles in Physical Sciences and Mathematics
Neutron Scattering At The Intersection Of Heart Health Science And Biophysics, Drew Marquardt, Richard J. Alsop, Maikel C. Rheinstädter, Thad A. Harroun
Neutron Scattering At The Intersection Of Heart Health Science And Biophysics, Drew Marquardt, Richard J. Alsop, Maikel C. Rheinstädter, Thad A. Harroun
Chemistry and Biochemistry Publications
There is an urgent quest for improved heart health. Here, we review how neutron radiation can provide insight into the molecular basis of heart health. Lower cholesterol, a daily intake of aspirin and supplemental vitamin E are argued to all improve heart health. However, the mechanisms behind these common regimens, and others, are not entirely understood. It is not clear why a daily intake of aspirin can help some people with heart disease, and the benefits of vitamin E in the treatment of reperfusion injury have been heavily debated. The molecular impact of cholesterol in the body is still a …
Asymmetric Lipid Membranes: Towards More Realistic Model Systems, Drew Marquardt, Barbara Geier, Georg Pabst
Asymmetric Lipid Membranes: Towards More Realistic Model Systems, Drew Marquardt, Barbara Geier, Georg Pabst
Chemistry and Biochemistry Publications
Despite the ubiquity of transbilayer asymmetry in natural cell membranes, the vast majority of existing research has utilized chemically well-defined symmetric liposomes, where the inner and outer bilayer leaflets have the same composition. Here, we review various aspects of asymmetry in nature and in model systems in anticipation for the next phase of model membrane studies.
Pcb Food Web Dynamics Quantify Nutrient And Energy Flow In Aquatic Ecosystems, Anne M. Mcleod, Gord Paterson, Ken G. Drouillard, Douglas G. Haffner
Pcb Food Web Dynamics Quantify Nutrient And Energy Flow In Aquatic Ecosystems, Anne M. Mcleod, Gord Paterson, Ken G. Drouillard, Douglas G. Haffner
Great Lakes Institute for Environmental Research Publications
Measuring in situ nutrient and energy flows in spatially and temporally complex aquatic ecosystems represents a major ecological challenge. Food web structure, energy and nutrient budgets are difficult to measure, and it is becoming more important to quantify both energy and nutrient flow to determine how food web processes and structure are being modified by multiple stressors. We propose that polychlorinated biphenyl (PCB) congeners represent an ideal tracer to quantify in situ energy and nutrient flow between trophic levels. Here, we demonstrate how an understanding of PCB congener bioaccumulation dynamics provides multiple direct measurements of energy and nutrient flow in …
Substrate-Assisted And Enzymatic Pretransfer Editing Of Nonstandard Amino Acids By Methionyl-Trna Synthetase, Grant B. Fortowsky, Daniel J. Simard, Mohamed M. Aboelnga, James W. Gauld
Substrate-Assisted And Enzymatic Pretransfer Editing Of Nonstandard Amino Acids By Methionyl-Trna Synthetase, Grant B. Fortowsky, Daniel J. Simard, Mohamed M. Aboelnga, James W. Gauld
Chemistry and Biochemistry Publications
Aminoacyl-tRNA synthetases (aaRSs) are cen- tral to a number of physiological processes, including protein biosynthesis. In particular, they activate and then transfer their corresponding amino acid to the cognate tRNA. This is achieved with a generally remarkably high fidelity by editing against incorrect standard and nonstandard amino acids. Using docking, molecular dynamics (MD), and hybrid quantum mechanical/molecular mechanics methods, we have inves- tigated mechanisms by which methionyl-tRNA synthetase (MetRS) may edit against the highly toxic, noncognate, amino acids homocysteine (Hcy) and its oxygen analogue, homo- serine (Hse). Substrate-assisted editing of Hcy-AMP in which its own phosphate acts as the mechanistic …
Aspirin Inhibits Formation Of Cholesterol Rafts In Fluid Lipid Membranes, Richard J. Alsop, Laura Toppozini, Drew Marquardt, Norbert Kučerka, Thad A. Harroun, Maikel C. Rheinstädter
Aspirin Inhibits Formation Of Cholesterol Rafts In Fluid Lipid Membranes, Richard J. Alsop, Laura Toppozini, Drew Marquardt, Norbert Kučerka, Thad A. Harroun, Maikel C. Rheinstädter
Chemistry and Biochemistry Publications
Aspirin and other non-steroidal anti-inflammatory drugs have a high affinity for phospholipid membranes, altering their structure and biophysical properties. Aspirin has been shown to partition into the lipid head groups, thereby increasing membrane fluidity. Cholesterol is another well known mediator of membrane fluidity, in turn increasing membrane stiffness. As well, cholesterol is believed to distribute unevenly within lipid membranes leading to the formation of lipid rafts or plaques. In many studies, aspirin has increased positive outcomes for patients with high cholesterol. We are interested if these effects may be, at least partially, the result of a non-specific interaction between aspirin …
Hierarchical Analysis Of Genetic Structure In The Habitat-Specialist Eastern Sand Darter (Ammocrypta Pellucida), Robert Ginson, Ryan P. Walter, Nicholas E. Mandrak, Courtney L. Beneteau, Daniel D. Heath
Hierarchical Analysis Of Genetic Structure In The Habitat-Specialist Eastern Sand Darter (Ammocrypta Pellucida), Robert Ginson, Ryan P. Walter, Nicholas E. Mandrak, Courtney L. Beneteau, Daniel D. Heath
Great Lakes Institute for Environmental Research Publications
Quantifying spatial genetic structure can reveal the relative influences of contemporary and historic factors underlying localized and regional patterns of genetic diversity and gene flow - important considerations for the development of effective conservation efforts. Using 10 polymorphic microsatellite loci, we characterize genetic variation among populations across the range of the Eastern Sand Darter (Ammocrypta pellucida), a small riverine percid that is highly dependent on sandy substrate microhabitats. We tested for fine scale, regional, and historic patterns of genetic structure. As expected, significant differentiation was detected among rivers within drainages and among drainages. At finer scales, an unexpected lack of …
Benefits Of Turbid River Plume Habitat For Lake Erie Yellow Perch (Perca Flavescens) Recruitment Determined By Juvenile To Larval Genotype Assignment, Lucia B. Carreon-Martinez, Ryan P. Walter, Timothy B. Johnson, Stuart A. Ludsin, Daniel D. Heath
Benefits Of Turbid River Plume Habitat For Lake Erie Yellow Perch (Perca Flavescens) Recruitment Determined By Juvenile To Larval Genotype Assignment, Lucia B. Carreon-Martinez, Ryan P. Walter, Timothy B. Johnson, Stuart A. Ludsin, Daniel D. Heath
Great Lakes Institute for Environmental Research Publications
Nutrient-rich, turbid river plumes that are common to large lakes and coastal marine ecosystems have been hypothesized to benefit survival of fish during early life stages by increasing food availability and (or) reducing vulnerability to visual predators. However, evidence that river plumes truly benefit the recruitment process remains meager for both freshwater and marine fishes. Here, we use genotype assignment between juvenile and larval yellow perch (Perca flavescens) from western Lake Erie to estimate and compare recruitment to the age-0 juvenile stage for larvae residing inside the highly turbid, south-shore Maumee River plume versus those occupying the less turbid, more …
Particle Backtracking Improves Breeding Subpopulation Discrimination And Natal-Source Identification In Mixed Populations, Michael E. Fraker, Eric J. Anderson, Reed M. Brodnik, Lucia Carreon-Martinez, Kristen M. Devanna, Brian J. Fryer, Daniel D. Heath, Julie M. Reichert, Stuart A. Ludsin
Particle Backtracking Improves Breeding Subpopulation Discrimination And Natal-Source Identification In Mixed Populations, Michael E. Fraker, Eric J. Anderson, Reed M. Brodnik, Lucia Carreon-Martinez, Kristen M. Devanna, Brian J. Fryer, Daniel D. Heath, Julie M. Reichert, Stuart A. Ludsin
Great Lakes Institute for Environmental Research Publications
We provide a novel method to improve the use of natural tagging approaches for subpopulation discrimination and source-origin identification in aquatic and terrestrial animals with a passive dispersive phase. Our method integrates observed site-referenced biological information on individuals in mixed populations with a particle-tracking model to retrace likely dispersal histories prior to capture (i.e., particle backtracking). To illustrate and test our approach, we focus on western Lake Erie's yellow perch (Perca flavescens) population during 2006-2007, using microsatellite DNA and otolith microchemistry from larvae and juveniles as natural tags. Particle backtracking showed that not all larvae collected near a presumed hatching …
Effect Of Cod: So42- Ratio, Hrt And Linoleic Acid Concentration On Mesophilic Sulfate Reduction: Reactor Performance And Microbial Population Dynamics, Chungman Moon, Rajesh Singh, Sathyanarayan S. Veeravalli, Saravanan R. Shanmugam, Subba Rao Chaganti, Jerald A. Lalman, Daniel D. Heath
Effect Of Cod: So42- Ratio, Hrt And Linoleic Acid Concentration On Mesophilic Sulfate Reduction: Reactor Performance And Microbial Population Dynamics, Chungman Moon, Rajesh Singh, Sathyanarayan S. Veeravalli, Saravanan R. Shanmugam, Subba Rao Chaganti, Jerald A. Lalman, Daniel D. Heath
Great Lakes Institute for Environmental Research Publications
Biological sulfate (SO42-) reduction was examined in anaerobic sequential batch reactors (ASBRs) operated under different hydraulic retention times (HRTs) ranging from 12 to 36 h and COD (Chemical Oxygen Demand)/SO42- ratios of 2.4, 1.6 and 0.8. Competition between SO42- reducing bacteria (SRBs), methane producing archaea (MPAs) and homoacetogens (HACs) was examined in controls and cultures treated with linoleic acid (LA). The ASBR performance was influenced by the COD/SO42- ratio in control cultures with a SO42- reduction of 87% at a COD/SO42- ratio of 0.8. At a 12 h HRT, in both control and LA treated cultures, greater than 75% SO42- …
The Effects Of Inbreeding On Sperm Quality Traits In Captive-Bred Lake Trout, Salvelinus Namaycush (Walbaum, 1972), K. Johnson, Ian A.E. Butts, J. L. Smith, C. C. Wilson, Trevor E. Pitcher
The Effects Of Inbreeding On Sperm Quality Traits In Captive-Bred Lake Trout, Salvelinus Namaycush (Walbaum, 1972), K. Johnson, Ian A.E. Butts, J. L. Smith, C. C. Wilson, Trevor E. Pitcher
Great Lakes Institute for Environmental Research Publications
The effects of inbreeding in both captive and wild-caught species and populations have been reported to affect a wide variety of life history traits. Recently, the effects of inbreeding on reproductive traits such as sperm quality have become a subject of particular interest for conservation biology, evolutionary ecology, and management of captive populations. This study investigated the effects of inbreeding on sperm quality in a captive population of experimentally inbred and outbred lake trout, Salvelinus namaycush. It was found for moderately to highly inbred males (males with half-sib and full-sib parents, respectively), that sperm quality traits (velocity, motility, linearity, longevity, …
Odd-Even Effects In Charge Transport Across N-Alkanethiolate-Based Sams, Mostafa Baghbanzadeh, Felice C. Simeone, Carleen M. Bowers, Kung Ching Liao, Martin Thuo, Mahdi Baghbanzadeh, Michael S. Miller, Tricia Breen Carmichael, George M. Whitesides
Odd-Even Effects In Charge Transport Across N-Alkanethiolate-Based Sams, Mostafa Baghbanzadeh, Felice C. Simeone, Carleen M. Bowers, Kung Ching Liao, Martin Thuo, Mahdi Baghbanzadeh, Michael S. Miller, Tricia Breen Carmichael, George M. Whitesides
Chemistry and Biochemistry Publications
This paper compares rates of charge transport across self-assembled monolayers (SAMs) of n-alkanethiolates having odd and even numbers of carbon atoms (nodd and neven) using junctions with the structure MTS/SAM//Ga2O3/EGaIn (M = Au or Ag). Measurements of current density, J(V), across SAMs of n-alkanethiolates on AuTS and AgTS demonstrated a statistically significant odd-even effect on AuTS, but not on AgTS, that could be detected using this technique. Statistical analysis showed the values of tunneling current density across SAMs of n-alkanethiolates on AuTS with nodd and neven belonging to two separate sets, and while there is a significant difference between the …
Ultrasmooth Gold Surfaces Prepared By Chemical Mechanical Polishing For Applications In Nanoscience, Michael S. Miller, Michael Anthony Ferrato, Adrian Niec, Mark C. Biesinger, Tricia Breen Carmichael
Ultrasmooth Gold Surfaces Prepared By Chemical Mechanical Polishing For Applications In Nanoscience, Michael S. Miller, Michael Anthony Ferrato, Adrian Niec, Mark C. Biesinger, Tricia Breen Carmichael
Chemistry and Biochemistry Publications
For over 20 years, template stripping has been the best method for preparing ultrasmooth metal surfaces for studies of nanostructures. However, the organic adhesives used in the template stripping method are incompatible with many solvents, limiting the conditions that may subsequently be used to prepare samples; in addition, the film areas that can be reliably prepared are typically limited to ∼1 cm2. In this article, we present chemical-mechanical polishing (CMP) as an adhesive-free, scalable method of preparing ultrasmooth gold surfaces. In this process, a gold film is first deposited by e-beam evaporation onto a 76-mm-diameter silicon wafer. The CMP process …
Activated Cyclopropanes: A Remarkable Breadth Of Recent Chemistry, James R. Green, Victor Snieckus
Activated Cyclopropanes: A Remarkable Breadth Of Recent Chemistry, James R. Green, Victor Snieckus
Chemistry and Biochemistry Publications
The reactions of cyclopropanes activated by electron-withdrawing groups and electron-donating groups – donor–acceptor (DA) cyclopropanes – and with alkenyl or alkylidene substituents has been an area of recent intense research activity. This Cluster contains contributions from many of the leading research groups in this area, and provides a concise introduction to the rich ring-opening, ring-expansion, dimerization, and cycloaddition chemistry of these compounds.
Synthesis Of Tenuifolin Via Intramolecular Nicholas Reaction, Sinisa Djurdjevic, James R. Green
Synthesis Of Tenuifolin Via Intramolecular Nicholas Reaction, Sinisa Djurdjevic, James R. Green
Chemistry and Biochemistry Publications
The synthesis of the Cinnamomum homosesquiterpenoid tenuifolin has been accomplished by way of an intramolecular Nicholas reaction of the [Co2(CO)6] complex of an alkyne-substituted biaryl for construction of the seven-membered ring. The cyclization features the reaction of a nonactivated arene ring with the propargyldicobalt cation to give the dibenzocycloheptyne-Co2(CO)6.
The Potential Of Quinoline Derivatives For The Treatment Of Toxoplasma Gondii Infection., Sirinart Ananvoranich
The Potential Of Quinoline Derivatives For The Treatment Of Toxoplasma Gondii Infection., Sirinart Ananvoranich
Chemistry and Biochemistry Publications
Here we reported our investigation, as part of our drug repositioning effort, on anti-Toxoplasma properties of newly synthesized quinoline compounds. A collection of 4-aminoquinoline and 4-piperazinylquinoline analogs have recently been synthesized for use in cancer chemotherapy. Some analogs were able to outperform chloroquine, a quinoline derivative drug which is commonly used in the treatment of malaria and other parasitic infections. Herein 58 compounds containing one or two quinoline rings were examined for their effectiveness as potential anti-Toxoplasma compounds. Of these 58 compounds, 32 were efficient at inhibiting Toxoplasma growth (IC50μM). Five compounds with single and simple quinoline rings exhibited similar …
A Multi-Scale Computational Study On The Mechanism Of Streptococcus Pneumoniae Nicotinamidase (Spnic), Bogdan F. Ion, Erum Kazim, James Gauld
A Multi-Scale Computational Study On The Mechanism Of Streptococcus Pneumoniae Nicotinamidase (Spnic), Bogdan F. Ion, Erum Kazim, James Gauld
Chemistry and Biochemistry Publications
Nicotinamidase (Nic) is a key zinc-dependent enzyme in NAD metabolism that catalyzes the hydrolysis of nicotinamide to give nicotinic acid. A multi-scale computational approach has been used to investigate the catalytic mechanism, substrate binding and roles of active site residues of Nic from Streptococcus pneumoniae (SpNic). In particular, density functional theory (DFT), molecular dynamics (MD) and ONIOM quantum mechanics/molecular mechanics (QM/MM) methods have been employed. The overall mechanism occurs in two stages: (i) formation of a thioester enzyme-intermediate (IC2) and (ii) hydrolysis of the thioester bond to give the products. The polar protein environment has a significant effect in stabilizing …
Novel Analogue Of Colchicine Induces Selective Pro-Death Autophagy And Necrosis In Human Cancer Cells, Kristen Elizabeth Larocque, Pamela Ovadje, Sinisa Djurdjevic, Mariam Mehdi, James R. Green, Siyaram Pandey
Novel Analogue Of Colchicine Induces Selective Pro-Death Autophagy And Necrosis In Human Cancer Cells, Kristen Elizabeth Larocque, Pamela Ovadje, Sinisa Djurdjevic, Mariam Mehdi, James R. Green, Siyaram Pandey
Chemistry and Biochemistry Publications
Colchicine, a natural product of Colchicum autumnae currently used for gout treatment, is a tubulin targeting compound which inhibits microtubule formation by targeting fast dividing cells. This tubulin-targeting property has lead researchers to investigate the potential of colchicine and analogs as possible cancer therapies. One major study conducted on an analogue of allocolchicine, ZD 6126, was halted in phase 2 clinical trials due to severe cardio-toxicity associated with treatment. This study involves the development and testing of novel allocolchicine analogues that hold non-toxic anti-cancer properties. Currently we have synthesized and evaluated the anti-cancer activities of two analogues; N-acetyl-O-methylcolchinol (NSC 51046 …
Multi-Scale Computational Enzymology: Enhancing Our Understanding Of Enzymatic Catalysis, Rami Gherib, Hisham Mohammed Mohammed Dokainish, James Gauld
Multi-Scale Computational Enzymology: Enhancing Our Understanding Of Enzymatic Catalysis, Rami Gherib, Hisham Mohammed Mohammed Dokainish, James Gauld
Chemistry and Biochemistry Publications
Elucidating the origin of enzymatic catalysis stands as one the great challenges of contemporary biochemistry and biophysics. The recent emergence of computational enzymology has enhanced our atomistic-level description of biocatalysis as well the kinetic and thermodynamic properties of their mechanisms. There exists a diversity of computational methods allowing the investigation of specific enzymatic properties. Small or large density functional theory models allow the comparison of a plethora of mechanistic reactive species and divergent catalytic pathways. Molecular docking can model different substrate conformations embedded within enzyme active sites and determine those with optimal binding affinities. Molecular dynamics simulations provide insights into …
Nicholas Reactions In The Synthesis Of Dicobalt Dibenzocyclooctyne Complexes, Sinisa Djurdjevic, James R. Green
Nicholas Reactions In The Synthesis Of Dicobalt Dibenzocyclooctyne Complexes, Sinisa Djurdjevic, James R. Green
Chemistry and Biochemistry Publications
Hexacarbonyldicobalt complexes of biaryl-substituted 4-methoxybutynones and 4-methoxy-2-butynes undergo intramolecular Nicholas reactions to form dibenzocyclooctyne–Co2(CO)6 complexes in good yields. Reductive decomplexation of the cyclization products is possible, and the method has been applied to a formal synthesis of isoschizandrin.
The Observation Of Highly Ordered Domains In Membranes With Cholesterol, Clare L. Armstrong, Drew Marquardt, Hannah Dies, Norbert Kučerka, Zahra Yamani, Thad A. Harroun, John Katsaras, An Chang Shi, Maikel C. Rheinstädter
The Observation Of Highly Ordered Domains In Membranes With Cholesterol, Clare L. Armstrong, Drew Marquardt, Hannah Dies, Norbert Kučerka, Zahra Yamani, Thad A. Harroun, John Katsaras, An Chang Shi, Maikel C. Rheinstädter
Chemistry and Biochemistry Publications
Rafts, or functional domains, are transient nano- or mesoscopic structures in the exoplasmic leaflet of the plasma membrane, and are thought to be essential for many cellular processes. Using neutron diffraction and computer modelling, we present evidence for the existence of highly ordered lipid domains in the cholesterol-rich (32.5 mol%) liquid-ordered (l0) phase of dipalmitoylphosphatidylcholine membranes. The liquid ordered phase in one-component lipid membranes has previously been thought to be a homogeneous phase. The presence of highly ordered lipid domains embedded in a disordered lipid matrix implies non-uniform distribution of cholesterol between the two phases. The experimental results are in …
Sperm Quality Of Hatchery-Reared Lake Trout Throughout The Spawning Season, Katelynn Johnson, Ian A.E. Butts, Chris C. Wilson, Trevor E. Pitcher
Sperm Quality Of Hatchery-Reared Lake Trout Throughout The Spawning Season, Katelynn Johnson, Ian A.E. Butts, Chris C. Wilson, Trevor E. Pitcher
Great Lakes Institute for Environmental Research Publications
The objective of this study was to investigate variation in sperm quality metrics (motility, velocity, linearity, longevity, and density) of hatchery-reared Lake Trout Salvelinus namaycush throughout the spawning season. Seasonal variation in sperm quality was investigated using both a regression and repeated-measures approach. Sperm was collected from the same 16 individuals over four sampling periods, separated by 3-week intervals. Regression analyses showed that 727% of the variation in sperm traits could be explained by seasonal variation, indicating that seasonality can have a significant impact on the quality of sperm. Significant positive linear relationships were found for percent motility and linearity …
Bicatalytic Allylation–Cross-Metathesis Reactions As Γ-Carbonyl Cation Equivalents, Jake R. Henkie, Sugadar Dhaliwal, James R. Green
Bicatalytic Allylation–Cross-Metathesis Reactions As Γ-Carbonyl Cation Equivalents, Jake R. Henkie, Sugadar Dhaliwal, James R. Green
Chemistry and Biochemistry Publications
The products corresponding to the reactions of arenes and γ-carbonyl cations may be obtained by a one-pot, bicatalytic process involving InCl3-catalyzed arene allylation and cross metathesis with electron-deficient alkenes. The process is successful with electronically neutral and electron-rich arenes, and modestly Lewis basic donor groups are tolerated with an increase in InCl3 loading from 10 mol% to 15 mol%, and in one case, 20 mol%.
A Molecular Dynamics (Md) And Quantum Mechanics/Molecular Mechanics (Qm/Mm) Study On Ornithine Cyclodeaminase (Ocd): A Tale Of Two Iminiums, Bogdan F. Ion, Eric Andre Bushnell, Phil De Luna, James Gauld
A Molecular Dynamics (Md) And Quantum Mechanics/Molecular Mechanics (Qm/Mm) Study On Ornithine Cyclodeaminase (Ocd): A Tale Of Two Iminiums, Bogdan F. Ion, Eric Andre Bushnell, Phil De Luna, James Gauld
Chemistry and Biochemistry Publications
Ornithine cyclodeaminase (OCD) is an NAD+-dependent deaminase that is found in bacterial species such as Pseudomonas putida. Importantly, it catalyzes the direct conversion of the amino acid L-ornithine to L-proline. Using molecular dynamics (MD) and a hybrid quantum mechanics/molecular mechanics (QM/MM) method in the ONIOM formalism, the catalytic mechanism of OCD has been examined. The rate limiting step is calculated to be the initial step in the overall mechanism: hydride transfer from the L-ornithine’s Cα–H group to the NAD+cofactor with concomitant formation of a Cα=NH2+ Schiff base with a barrier …
Alkynedicobalt Complexes In Γ-Carbonyl Cations And Cycloheptynedicobalt Complexes, James R. Green
Alkynedicobalt Complexes In Γ-Carbonyl Cations And Cycloheptynedicobalt Complexes, James R. Green
Chemistry and Biochemistry Publications
This Account describes our work on highly electrophilic γ-carbonyl cations featuring propargyldicobalt cations, cycloheptynedicobalt complexes, and the interconnection between the two systems.
1 Introduction
2 γ-Carbonyl Cations via Iron Allyl Cations
3 γ-Carbonyl Cations via Propargyldicobalt Cations
3.1 Synthesis of Velloziolide
3.2 Synthesis of Microstegiol
4 Synthesis of Cycloheptynedicobalt Complexes
4.1 Synthesis via γ-Carbonyl Cations
4.2 Cycloheptynedicobalt Complexes via [4+3] Cycloaddition Reactions
4.3 Cycloheptynedicobalt Complexes via Ring-Closing Metathesis
4.4 Cycloaddition Reactions on Cycloheptynedicobalt Complexes
4.5 Cycloheptynedicobalt Complexes via Intramolecular Nicholas Reactions
5 Dehydrotropylium Ion Co2(CO)6 Complex
6 Final Comments
Low Levels Of Extra-Pair Paternity In A Neotropical Duetting Songbird, The Rufous-And-White Wren (Thryothorus Rufalbus), Sarah B. Douglas, Daniel D. Heath, Daniel J. Mennill
Low Levels Of Extra-Pair Paternity In A Neotropical Duetting Songbird, The Rufous-And-White Wren (Thryothorus Rufalbus), Sarah B. Douglas, Daniel D. Heath, Daniel J. Mennill
Great Lakes Institute for Environmental Research Publications
Molecular analyses have confirmed that the majority of socially monogamous birds follow a genetically promiscuous reproductive strategy. Most such studies, however, have addressed species of the North Temperate Zone; tropical species are grossly underrepresented, although most of Earth's biodiversity is concentrated in the tropics. In this study, we describe the genetic mating strategy of the Rufous-and-white Wren (Thryothorus rufalbus), a socially monogamous duetting neotropical songbird. Over 8 years of studying a marked population in Costa Rica, we recorded genetic data from 51 broods. Microsatellite analysis of four variable loci revealed that the Rufous-and-white Wren follows a mixed reproductive strategy, where …
Co2 Production In The Bromate-1,4-Cyclohexanedione Oscillatory Reaction, Jiamin Feng, James R. Green, Samuel A. Johnson, Jichang Wang
Co2 Production In The Bromate-1,4-Cyclohexanedione Oscillatory Reaction, Jiamin Feng, James R. Green, Samuel A. Johnson, Jichang Wang
Chemistry and Biochemistry Publications
NMR and GC/MS spectroscopy of the organic extracts of the oscillatory bromate-1,4-cyclohexanedione reaction illustrate the presence of ring-opening products 5-(dibromomethylene)-2(5H)-furanone, (E)-5,5,5-tribromo-4-oxo-2-pentenoic acid, and dibromoacetic acid, particularly at elevated temperatures. The loss of a carbon atom from the six-membered ring after ring opening led to gas formation and such a process became more vigorous at >60 °C, with the direct observation of bubbles in a stirred batch reactor. Gravimetric experiments confirm that the amount of carbon dioxide gas produced increases rapidly with reaction temperature. Parallel experiments suggest that the ring-opening process involves the oxidation of brominated benzoquinones by bromate. Copyright © …
Dehydrotropylium-Co2(Co)6 Ion. Generation, Reactivity And Evaluation Of Cation Stability, Sheida Amiralaei, James Gauld, James R. Green
Dehydrotropylium-Co2(Co)6 Ion. Generation, Reactivity And Evaluation Of Cation Stability, Sheida Amiralaei, James Gauld, James R. Green
Chemistry and Biochemistry Publications
The dehydrotropylium–Co2(CO)6 ion was generated by the action of HBF4 or BF3⋅OEt2 on the corresponding cycloheptadienynol complex, which in turn has been prepared in four steps from a known diacetoxycycloheptenyne complex. The reaction of the cycloheptadienynol complex via the dehydrotropylium–Co2(CO)6 ion with several nucleophiles results in substitution reactions with reactive nucleophiles (N>1) under normal conditions, and a radical dimerisation reaction in the presence of less reactive nucleophiles. Competitive reactions of the cycloheptadienynol complex with an acyclic trienynol complex show no preference for generation of the dehydrotropylium–Co2 …
Synthesis Of ‘Spacer’-Naproxen [2-(6-Methoxybiphenylen-2-Yl)Propanoic Acid] And -Isonaproxen [2-(7-Methoxybiphenylen-2-Yl)Propanoic Acid], Juan A. González Gómez, James R. Green, Peter C. Vollhardt
Synthesis Of ‘Spacer’-Naproxen [2-(6-Methoxybiphenylen-2-Yl)Propanoic Acid] And -Isonaproxen [2-(7-Methoxybiphenylen-2-Yl)Propanoic Acid], Juan A. González Gómez, James R. Green, Peter C. Vollhardt
Chemistry and Biochemistry Publications
The CpCo(CO)2-catalyzed cocyclization of 1,2-diethynyl- 4-methoxybenzene with alkynes can be applied to the synthesis of ‘spacer’-naproxen [2-(6-methoxybiphenylen-2-yl)propanoic acid] and its 7-methoxy isomer, ‘spacer’-isonaproxen. While unsymmetrical alkynes are incorporated without regioselectivity, the methoxy group in 6-methoxy-2,3-bis(trimethylsilyl)biphenylene directs electrophiles to C-3, thus allowing for regiochemical differentiation between the 2- and 3-positions.
Juvenile Habitat Partitioning And Relative Productivity In Allochronically Isolated Sockeye Salmon (Oncorhynchus Nerka), E. K. Fillatre Miller, I. R. Bradbury, Daniel D. Heath
Juvenile Habitat Partitioning And Relative Productivity In Allochronically Isolated Sockeye Salmon (Oncorhynchus Nerka), E. K. Fillatre Miller, I. R. Bradbury, Daniel D. Heath
Great Lakes Institute for Environmental Research Publications
Allochronic divergence, like spatial isolation, may contribute to population diversity and adaptation, however the challenges for tracking habitat utilization in shared environments are far greater. Adult Klukshu River (Yukon, Canada) sockeye salmon, Oncorhynchus nerka, return as genetically distinct "early" and "late" runs. Early and late adult spawning populations (1999 and 2000) and their subsequent fry (sampled at 7 sites in 2000 and at 8 sites in 2001 throughout Klukshu Lake and River) were genotyped at eight microsatellite loci. Bayesian assignment was used to determine the spatial distribution of early versus late fry; although intermixed, the distribution of fry significantly differed …
Nicholas Reactions In The Construction Of Cyclohepta[De]Naphthalenes And Cyclohepta[De]Naphthalenones. The Total Synthesis Of Microstegiol, Rafiq Taj, James R. Green
Nicholas Reactions In The Construction Of Cyclohepta[De]Naphthalenes And Cyclohepta[De]Naphthalenones. The Total Synthesis Of Microstegiol, Rafiq Taj, James R. Green
Chemistry and Biochemistry Publications
The application of the Nicholas reaction chemistry of 2,7-dioxygenated naphthalenes in the synthesis of cyclohepta[de]napthalenes and in the synthesis of (±)-microstegiol (1) is presented. The substitution profile of Nicholas monosubstitution (predominantly C-1) and disubstitution reactions (predominantly 1,6-) on 2,7-dioxygenated napthalenes is reported. Application of a 1,8-dicondensation product and selected C-1 monocondensation products to the construction of cyclohepta[de]naphthalenes by way of ring closing metathesis and intramolecular Friedel−Crafts reactions, respectively, is described. Deprotection of the C-7 oxygen function to the corresponding naphthol allows tautomerization to cyclohepta[de]naphthalene-1-ones upon seven-membered-ring closure in most cases, and replacement …