Purpose: We examined iron absorption and its regulation during two common scenarios experienced by endurance athletes. Our aims were to: (i) compare the effects of preexercise versus postexercise iron intake on iron absorption; and (ii) compare the impact of training at altitude (1800 m) on iron absorption preexercise.
Methods: Male runners (n = 18) completed three exercise trials over a 5-wk period, each preceded by 24 h of standardized low-iron diets.
Estimating the elastic modulus and strength of heterogeneous films requires local measurement techniques. For local mechanical film testing, microcantilevers were cut into suspended many-layer graphene using a focused ion beam. An optical transmittance technique was used to map thickness near the cantilevers, and multipoint force-deflection mapping with an atomic force microscope was used to record the compliance of the cantilevers.
View Article and Find Full Text PDFThe electronic structure of copper corroles has been a topic of debate and revision since the advent of corrole chemistry. The ground state of these compounds is best described as an antiferromagnetically coupled Cu(II) corrole radical cation. In coordinating solvents, these molecules become paramagnetic, and this is often accompanied by a color change.
View Article and Find Full Text PDFIntroduction: Although an acute exercise session typically increases bone turnover markers (BTM), the impact of subsequent sessions and the interaction with preexercise calcium intake remain unclear despite the application to the "real-life" training of many competitive athletes.
Methods: Using a randomized crossover design, elite male rowers ( n = 16) completed two trials, a week apart, consisting of two 90-min rowing ergometer sessions (EX1, EX2) separated by 150 min. Before each trial, participants consumed a high (CAL; ~1000 mg) or isocaloric low (CON; <10 mg) calcium meal.
Previous research investigating single bouts of exercise have identified baseline iron status and circulating concentrations of interleukin-6 (IL-6) as contributors to the magnitude of postexercise hepcidin increase. The current study examined the effects of repeated training bouts in close succession on IL-6 and hepcidin responses. In a randomized, crossover design, 16 elite male rowers completed two trials, a week apart, with either high (1,000 mg) or low (<50 mg) calcium pre-exercise meals.
View Article and Find Full Text PDFIn head and neck squamous cell carcinoma (HNSCC) tumors that over-expresses huEGFR, the anti-EGFR antibody, cetuximab, antagonizes tumor cell viability and sensitizes to radiation therapy. However, the immunologic interactions between cetuximab and radiation therapy are not well understood. We transduced two syngeneic murine HNSCC tumor cell lines to express human EGFR (MOC1- and MOC2-huEGFR) in order to facilitate evaluation of the immunologic interactions between radiation and cetuximab.
View Article and Find Full Text PDFBackground: Immune checkpoint inhibition (ICI) alone is not efficacious for a large number of patients with melanoma brain metastases. We previously established an in situ vaccination (ISV) regimen combining radiation and immunocytokine to enhance response to ICIs. Here, we tested whether ISV inhibits the development of brain metastases in a murine melanoma model.
View Article and Find Full Text PDFA Mn(iv) complex featuring a terminal oxo ligand, [Mn(O)(ditox)][K(15-C-5)] (; ditox = BuMeCO, 15-C-5 = 15-crown-5-ether) has been isolated and structurally characterized. Treatment of the colorless precursor [Mn(ditox)][K(15-C-5)] () with iodosobenzene affords as a green free-flowing powder in high yields. The X-ray crystal structure of reveals a pseudotetrahedral geometry about the central Mn, which features a terminal oxo ((Mn-O = 1.
View Article and Find Full Text PDFHalogen photoelimination is the critical energy-storing step of metal-catalyzed HX-splitting photocycles. Homo- and heterobimetallic Pt(III) complexes display among the highest quantum efficiencies for halogen elimination reactions. Herein, we examine in detail the mechanism and energetics of halogen elimination from a family of binuclear Pt(III) complexes featuring meridionally coordinated Pt(III) trichlorides.
View Article and Find Full Text PDFThe ground state electronic structure of copper corroles has been a topic of debate and revision since the advent of corrole chemistry. Computational studies formulate neutral Cu corroles with an antiferromagnetically coupled Cu(II) corrole radical cation ground state. X-ray photoelectron spectroscopy, EPR, and magnetometry support this assignment.
View Article and Find Full Text PDFTrioxadiborrins are chelating ligands that assemble in dehydration reactions of boronic acids. They are structurally related to β-diketonate ligands, but have a 2-charge. Little is known of the bonding properties of trioxadiborrin ligands.
View Article and Find Full Text PDFOrganic boroxines are ubiquitous, but metallaboroxine analogues remain rare. A new class of (boroxinato)gold species are demonstrated here, as are observations of phosphorescence from boroxinato complexes. Four new compounds are crystallographically characterized.
View Article and Find Full Text PDFHalogen photoelimination reactions constitute the oxidative half-reaction of closed HX-splitting energy storage cycles. Here, we report high-yielding, endothermic Cl2 photoelimination chemistry from mononuclear Ni(III) complexes. On the basis of time-resolved spectroscopy and steady-state photocrystallography experiments, a mechanism involving ligand-assisted halogen elimination is proposed.
View Article and Find Full Text PDFThe encapsulation of peroxide dianion by hexacarboxamide cryptand provides a platform for the study of electron transfer of isolated peroxide anion. Photoinitiated electron transfer (ET) between freely diffusing Ru(bpy)3(2+) and the peroxide dianion occurs with a rate constant of 2.0 × 10(10) M(-1) s(-1).
View Article and Find Full Text PDFThe observed water oxidation activity of the compound class Co4O4(OAc)4(Py-X)4 emanates from a Co(II) impurity. This impurity is oxidized to produce the well-known Co-OEC heterogeneous cobaltate catalyst, which is an active water oxidation catalyst. We present results from electron paramagnetic resonance spectroscopy, nuclear magnetic resonance line broadening analysis, and electrochemical titrations to establish the existence of the Co(II) impurity as the major source of water oxidation activity that has been reported for Co4O4 molecular cubanes.
View Article and Find Full Text PDFGeminally diaurated μ2 -aryl complexes have been prepared where gold(I) centers were bridged by the semirigid diphosphine ligands bis(2-diphenylphosphinophenyl)ether (DPEphos) and 4,6-bis(diphenylphosphanyl)dibenzo[b,d]furan (DBFphos). Diaurated complexes were synthesized in ligand redistribution reactions of the corresponding di-gold dichlorides with di-gold diaryls (six of them new) and silver(I) salts. Diaurated complexes were isolated as salts of the minimally coordinating anions SbF6 (-) and ReO4 (-).
View Article and Find Full Text PDFPolynuclear transition metal complexes, which frequently constitute the active sites of both biological and chemical catalysts, provide access to unique chemical transformations that are derived from metal-metal cooperation. Reductive elimination via ligand-bridged binuclear intermediates from bimetallic cores is one mechanism by which metals may cooperate during catalysis. We have established families of Rh2 complexes that participate in HX-splitting photocatalysis in which metal-metal cooperation is credited with the ability to achieve multielectron photochemical reactions in preference to single-electron transformations.
View Article and Find Full Text PDFPhotochemical HX splitting requires the management of two protons and the execution of multielectron photoreactions. Herein, we report a photoinduced two-electron reduction of a polypyridyl Ni(II) chloride complex that provides a route to H2 evolution from HCl. The excited states of Ni complexes are too short to participate directly in HX activation, and hence, the excited state of a photoredox mediator is exploited for the activation of HX at the Ni(II) center.
View Article and Find Full Text PDFHalogen photoelimination is a critical step in HX-splitting photocatalysis. Herein, we report the photoreduction of a pair of valence-isomeric dirhodium phosphazane complexes, and suggest that a common intermediate is accessed in the photochemistry of both mixed-valent and valence-symmetric complexes. The results of these investigations suggest that halogen photoelimination proceeds by two sequential photochemical reactions: ligand dissociation followed by subsequent halogen elimination.
View Article and Find Full Text PDFA dyad complex has been constructed as a soluble molecular model of a heterogeneous cobalt-based oxygen-evolving catalyst (Co-OEC). To this end, the Co(4)O(4) core of a cobalt-oxo cubane was covalently appended to Re(I) photosensitisers. The resulting adduct was characterised both in the solid state (by X-ray diffraction) and in solution using a variety of techniques.
View Article and Find Full Text PDFIncorporation of 2,3,6-trifluorotyrosine (F(3)Y) and a rhenium bipyridine ([Re]) photooxidant into a peptide corresponding to the C-terminus of the β protein (βC19) of Escherichia coli ribonucleotide reductase (RNR) allows for the temporal monitoring of radical transport into the α2 subunit of RNR. Injection of the photogenerated F(3)Y radical from the [Re]-F(3)Y-βC19 peptide into the surface accessible Y731 of the α2 subunit is only possible when the second Y730 is present. With the Y-Y established, radical transport occurs with a rate constant of 3 × 10(5) s(-1).
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