11 research outputs found
Comparação entre diferentes equações antropométricas e a pletismografia para estimar o percentual de gordura de atletas masculinos de Taekwondo
TCC (Graduação) - Universidade Federal de Santa Catarina. Centro de Desportos. Educação Física - Bacharelado.O Taekwondo é um esporte de combate oriundo da Coréia, atualmente integrao quadro de esportes olímpicos, no qual tem suas lutas divididas por categorias de peso, que possui como principal característica os chutes, estes, que são definidos por fatores físicos e que correspondem a 98% dos gestos do combate. Por ser um esporte intermitente, solicita alta preparação física durante a competição, no qual uma luta tem duração aproximada de 8 min, e pelas mudanças ocorridas nos últimos anos, fez com que a antropometria dos atletas fosse um fator decisivo no resultado de uma luta. Pela falta de um protocolo qualificado, específico e válido para avaliar a composição corporal destes atletas, o presente estudo tem como objetivo verificar quais equações antropométricasapresenta maior correlação quando correlacionado com o método de pletismografia por deslocamento de ar para avaliação dopercentual de gordura de atletas masculinos de Taekwondo. Participaram da pesquisa 11 atletas de Taekwondo com idade entre 16 e 30 anos, que foram avaliados por meio de medidas antropométricas de dobras cutâneas, circunferências e perímetros e pelo método de referência pletismografiapor deslocamento de ar. Posteriormente analisou-se a correlação entre a pletismografia por deslocamento de ar e as equações antropométricas.Das nove equações utilizadas seis não apresentaram diferença significativa (p>0,05) com relação à pletismografiapor deslocamento de ar. Dentre estas, três equações apresentaram grande correlação e duas delas apresentaram correlação muito grande com r=914. Devido as características, Whiterset al. (1987) foi considerada a mais adequada para avaliar o %G de atletas masculinos de Taekwondo
Helical Preorganization of Molecules Drives Solid-State Intermolecular Acyl-Transfer Reactivity in Crystals: Structures and Reactivity Studies of Solvates of Racemic 2,6-Di‑<i>O</i>‑(4-fluorobenzoyl)-<i>myo</i>-inositol 1,3,5-Orthoformate
Racemic
2,6-di-<i>O</i>-(4-fluorobenzoyl)-<i>myo</i>-inositol
1,3,5-orthoformate yielded structurally dissimilar solvent-free
and solvated crystals depending upon the solvent of crystallization.
The solvated crystals exhibited helical assembly of host molecules,
due to the interaction of the guest molecules with the orthoformate
moiety of the host. Some of the solvates showed specific but incomplete
benzoyl group transfer reactivity below the phase transition temperature,
whereas the reaction in solvent-free crystals led to a mixture of
several products. These results reveal the necessity of helical molecular
packing of the reacting molecules in their crystals to facilitate
specific intermolecular acyl transfer reactivity. The crystal structures
of the fluorobenzoate solvates were similar to those of the solvates
of the analogous chloro and bromobenzoates. The latter could be thermally
transformed into their solvent-free form via melt crystallization,
resulting in the conversion of a helical molecular packing into a
nonhelical molecular packing
Reactions of CO<sub>2</sub> and CS<sub>2</sub> with [RuH(η<sup>2</sup>‑CH<sub>2</sub>PMe<sub>2</sub>)(PMe<sub>3</sub>)<sub>3</sub>]
Carbon disulfide reacted with the cyclometalated ruthenium
complex
[RuH(η<sup>2</sup>-CH<sub>2</sub>PMe<sub>2</sub>)(PMe<sub>3</sub>)<sub>3</sub>] (<b>1</b>) at low temperature to yield the dithioformate
complex [Ru(η<sup>1</sup>-SC(S)H)(η<sup>2</sup>-CH<sub>2</sub>PMe<sub>2</sub>)(PMe<sub>3</sub>)<sub>3</sub>] (<b>4</b>), where the CS<sub>2</sub> inserts into the metal hydride
bond. On warming, complex <b>4</b> rearranges to give the known
complex [Ru(S<sub>2</sub>CHPMe<sub>2</sub>CH<sub>2</sub>-κ<sup>3</sup><i>S</i>,<i>S</i>,<i>C</i>)(PMe<sub>3</sub>)<sub>3</sub>] (<b>3</b>), where the CS<sub>2</sub> is
inserted in a metal phosphorus bond. Further reaction of this complex
with excess CS<sub>2</sub> over a period of days resulted in insertion
of a second CS<sub>2</sub> unit into one Ru–S bond to yield
[Ru(SC(S)SCH(-S)PMe<sub>2</sub>CH<sub>2</sub>-κ<sup>3</sup><i>S</i>,<i>S</i>,<i>C</i>)(PMe<sub>3</sub>)<sub>3</sub>] (<b>5</b>). Complex <b>5</b> was
characterized crystallographically and by multinuclear NMR spectroscopy.
In contrast, reaction of [RuH(η<sup>2</sup>-CH<sub>2</sub>PMe<sub>2</sub>)(PMe<sub>3</sub>)<sub>3</sub>] (<b>1</b>) with CO<sub>2</sub> resulted in insertion of CO<sub>2</sub> into the Ru–C
bond to give [RuH(OC(O)CH<sub>2</sub>PMe<sub>2</sub>-κ<sup>2</sup><i>O</i>,<i>P</i>)(PMe<sub>3</sub>)<sub>3</sub>] (<b>2</b>). Low-temperature NMR spectroscopic studies
did not show any evidence for prior formation of a formate complex
A Capped Dipeptide Which Simultaneously Exhibits Gelation and Crystallization Behavior
Short
peptides capped at their N-terminus are often highly efficient
gelators, yet notoriously difficult to crystallize. This is due to
strong unidirectional interactions within fibers, resulting in structure
propagation only along one direction. Here, we synthesize the N-capped
dipeptide, benzimidazole-diphenylalanine, which forms both hydrogels
and single crystals. Even more remarkably, we show using atomic force
microscopy the coexistence of these two distinct phases. We then use
powder X-ray diffraction to investigate whether the single crystal
structure can be extrapolated to the molecular arrangement within
the hydrogel. The results suggest parallel β-sheet arrangement
as the dominant structural motif, challenging existing models for
gelation of short peptides, and providing new directions for the future
rational design of short peptide gelators
A Capped Dipeptide Which Simultaneously Exhibits Gelation and Crystallization Behavior
Short
peptides capped at their N-terminus are often highly efficient
gelators, yet notoriously difficult to crystallize. This is due to
strong unidirectional interactions within fibers, resulting in structure
propagation only along one direction. Here, we synthesize the N-capped
dipeptide, benzimidazole-diphenylalanine, which forms both hydrogels
and single crystals. Even more remarkably, we show using atomic force
microscopy the coexistence of these two distinct phases. We then use
powder X-ray diffraction to investigate whether the single crystal
structure can be extrapolated to the molecular arrangement within
the hydrogel. The results suggest parallel β-sheet arrangement
as the dominant structural motif, challenging existing models for
gelation of short peptides, and providing new directions for the future
rational design of short peptide gelators
Rhodium Complexes of a Chelating Ligand with Imidazol-2-ylidene and Pyridin-2-ylidene Donors: The Effect of <i>C</i>-Metalation of Nicotinamide Groups on Uptake of Hydride Ion
Rhodium complexes of the imidazolylidene (<i>C</i>-im) <i>N</i>-heterocyclic carbene (NHC) ligand, <i>C</i>-im-pyH<sup>+</sup>, bearing a nicotinamide cation substituent
(pyH<sup>+</sup>) have been targeted for ligand-centered uptake and
delivery of hydride
ion. This work reveals that rhodium(I) complexes such as [Rh(<i>C</i>-im-pyH<sup>+</sup>)(COD)X][PF<sub>6</sub>] (<b>1</b>, <b>a</b>: X = Cl, <b>b</b>: X = I) undergo facile <i>C</i>-metalation of the nicotinamide ring to afford rhodium
complexes of a novel chelate ligand, <i>C,C′</i>-im-py,
with coordinated imidazolylidene (C<sub>im</sub>) and pyridylidene
(C<sub>py</sub>) NHC-donors. Seven examples were characterized and
include rhodium(III) monomers of the general formula [Rh(<i>C,C′</i>-im-py)L<sub><i>x</i></sub>I<sub>2</sub>]<sup><i>z</i>+</sup> (<b>2</b>: <i>z</i> = 1, L = H<sub>2</sub>O or solvent, <i>x</i> = 2; <b>3</b>, <b>5</b>, <b>7</b>: <i>z</i> = 0, L = carboxylate, <i>x</i> = 1) and novel rhodium(II) dimers, the <i>anti/syn</i>-isomers of [Rh<sub>2</sub>(<i>C,C′</i>-im-py)<sub>2</sub>(μOAc)<sub>2</sub>I<sub>2</sub>] (<b>4-</b><i><b>anti</b></i>/<i><b>syn</b></i>). The
NMR data, backed by DFT calculations, is consistent with attribution
of the <i>C,C′</i>-im-py ligand as a bis(carbene)
donor. Single crystal X-ray diffraction studies are reported for <b>2</b>, <b>3</b>, <b>4-</b><i><b>anti</b></i>, <b>4-</b><i><b>syn</b></i> and <b>7</b>. Consistently, within the each complex, the Rh–C<sub>im</sub> bond length is shorter than the Rh–C<sub>py</sub> bond length, which is the opposite trend to that expected based
on simple electronic considerations. It is proposed that intramolecular
steric interactions imposed by different rings in the rigid <i>C,C′</i>-im-py chelate ligand dictate the observed Rh–C<sub>NHC</sub> bond lengths. Attempts to add hydride to the <i>C</i>-metalated nicotinamide ring in <b>3</b> were unsuccessful.
The redox behavior of <b>3</b> and <b>4</b> and, for comparison,
an analogous bis(imidazolylidene)rhodium(III) monomer (<b>8</b>), were characterized by cyclic voltammetry, electron paramagnetic
resonance (EPR), and UV–vis spectroelectrochemistry. In <b>3</b> and <b>4</b>, the <i>C</i>-metalated nicotinamide
ring is found to exhibit a one-electron reduction process at far lower
potential (−2.34 V vs. Fc<sup>+</sup>/Fc in acetonitrile) than
the two-electron nicotinamide cation-dihydronicotinamide couple found
for the corresponding nonmetalated ring (−1.24 V). The <i>C,C′</i>-ligand is electrochemically silent over a large
potential range (from −2.3 V to the anodic solvent limit),
thus for both <b>3</b> and <b>4</b> the first reduction
processes are metal-centered. For <b>4-</b><i><b>anti</b></i>, the cyclic voltammetry and UV–vis spectrochemical
results are consistent with a diamagnetic [Rh(I)Rh(II)]<sub>2</sub> tetrameric reduction product. Density functional theory (DFT) calculations
were used to further probe the uptake of hydride ion by the nicotinamide
ring, both before and after <i>C</i>-metalation. It is found
that <i>C</i>-metalation significantly decreases the ability
of the nicotinamide ring to take up hydride ion, which is attributed
to the “carbene-like” character of a <i>C</i>-metalated pyridylidene ring
Reactions of CO<sub>2</sub> and CS<sub>2</sub> with [RuH(η<sup>2</sup>‑CH<sub>2</sub>PMe<sub>2</sub>)(PMe<sub>3</sub>)<sub>3</sub>]
Carbon disulfide reacted with the cyclometalated ruthenium
complex
[RuH(η<sup>2</sup>-CH<sub>2</sub>PMe<sub>2</sub>)(PMe<sub>3</sub>)<sub>3</sub>] (<b>1</b>) at low temperature to yield the dithioformate
complex [Ru(η<sup>1</sup>-SC(S)H)(η<sup>2</sup>-CH<sub>2</sub>PMe<sub>2</sub>)(PMe<sub>3</sub>)<sub>3</sub>] (<b>4</b>), where the CS<sub>2</sub> inserts into the metal hydride
bond. On warming, complex <b>4</b> rearranges to give the known
complex [Ru(S<sub>2</sub>CHPMe<sub>2</sub>CH<sub>2</sub>-κ<sup>3</sup><i>S</i>,<i>S</i>,<i>C</i>)(PMe<sub>3</sub>)<sub>3</sub>] (<b>3</b>), where the CS<sub>2</sub> is
inserted in a metal phosphorus bond. Further reaction of this complex
with excess CS<sub>2</sub> over a period of days resulted in insertion
of a second CS<sub>2</sub> unit into one Ru–S bond to yield
[Ru(SC(S)SCH(-S)PMe<sub>2</sub>CH<sub>2</sub>-κ<sup>3</sup><i>S</i>,<i>S</i>,<i>C</i>)(PMe<sub>3</sub>)<sub>3</sub>] (<b>5</b>). Complex <b>5</b> was
characterized crystallographically and by multinuclear NMR spectroscopy.
In contrast, reaction of [RuH(η<sup>2</sup>-CH<sub>2</sub>PMe<sub>2</sub>)(PMe<sub>3</sub>)<sub>3</sub>] (<b>1</b>) with CO<sub>2</sub> resulted in insertion of CO<sub>2</sub> into the Ru–C
bond to give [RuH(OC(O)CH<sub>2</sub>PMe<sub>2</sub>-κ<sup>2</sup><i>O</i>,<i>P</i>)(PMe<sub>3</sub>)<sub>3</sub>] (<b>2</b>). Low-temperature NMR spectroscopic studies
did not show any evidence for prior formation of a formate complex
Low Oxidation State Iron(0), Iron(I), and Ruthenium(0) Dinitrogen Complexes with a Very Bulky Neutral Phosphine Ligand
The
synthesis of a series of iron and ruthenium complexes with the ligand
P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>, P(CH<sub>2</sub>CH<sub>2</sub>PCy<sub>2</sub>)<sub>3</sub> is described. The iron(0) and ruthenium(0)
complexes Fe(N<sub>2</sub>)(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>) (<b>1</b>) and Ru(N<sub>2</sub>)(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>) (<b>2</b>) were synthesized by treatment of
[FeCl(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> and [RuCl(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> with an excess of
potassium graphite under a nitrogen atmosphere. The Fe(I) and Ru(I)
species [Fe(N<sub>2</sub>)(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> (<b>3</b>) and RuCl(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>) (<b>4</b>) were synthesized by treatment of
[FeCl(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> and [RuCl(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> with 1 equiv of potassium
graphite under a nitrogen atmosphere. The cationic dinitrogen species
[Fe(N<sub>2</sub>)H(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> (<b>6</b>) and [Ru(N<sub>2</sub>)H(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> (<b>7</b>) were formed by
treatment of <b>1</b> and <b>3</b>, respectively, with
1 equiv of a weak organic acid. The iron(II) complex Fe(H)<sub>2</sub>(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>) (<b>5</b>) was also
synthesized and characterized. Complexes [RuCl(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)][BPh<sub>4</sub>], <b>1</b>, <b>2</b>, <b>3[BPh</b><sub><b>4</b></sub><b>]</b>, <b>4</b>, <b>5</b>, <b>6[BF</b><sub><b>4</b></sub><b>]</b>, and <b>7[BF</b><sub><b>4</b></sub><b>]</b> were characterized by X-ray crystallography. The Fe(I) and
Ru(I) complexes <b>3</b> and <b>4</b> were characterized
by electron paramagnetic resonance (EPR) spectroscopy, and the Fe(I)
complex has an EPR spectrum typical of a metal-centered radical
Low Oxidation State Iron(0), Iron(I), and Ruthenium(0) Dinitrogen Complexes with a Very Bulky Neutral Phosphine Ligand
The
synthesis of a series of iron and ruthenium complexes with the ligand
P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>, P(CH<sub>2</sub>CH<sub>2</sub>PCy<sub>2</sub>)<sub>3</sub> is described. The iron(0) and ruthenium(0)
complexes Fe(N<sub>2</sub>)(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>) (<b>1</b>) and Ru(N<sub>2</sub>)(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>) (<b>2</b>) were synthesized by treatment of
[FeCl(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> and [RuCl(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> with an excess of
potassium graphite under a nitrogen atmosphere. The Fe(I) and Ru(I)
species [Fe(N<sub>2</sub>)(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> (<b>3</b>) and RuCl(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>) (<b>4</b>) were synthesized by treatment of
[FeCl(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> and [RuCl(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> with 1 equiv of potassium
graphite under a nitrogen atmosphere. The cationic dinitrogen species
[Fe(N<sub>2</sub>)H(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> (<b>6</b>) and [Ru(N<sub>2</sub>)H(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)]<sup>+</sup> (<b>7</b>) were formed by
treatment of <b>1</b> and <b>3</b>, respectively, with
1 equiv of a weak organic acid. The iron(II) complex Fe(H)<sub>2</sub>(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>) (<b>5</b>) was also
synthesized and characterized. Complexes [RuCl(P<sup>2</sup>P<sub>3</sub><sup>Cy</sup>)][BPh<sub>4</sub>], <b>1</b>, <b>2</b>, <b>3[BPh</b><sub><b>4</b></sub><b>]</b>, <b>4</b>, <b>5</b>, <b>6[BF</b><sub><b>4</b></sub><b>]</b>, and <b>7[BF</b><sub><b>4</b></sub><b>]</b> were characterized by X-ray crystallography. The Fe(I) and
Ru(I) complexes <b>3</b> and <b>4</b> were characterized
by electron paramagnetic resonance (EPR) spectroscopy, and the Fe(I)
complex has an EPR spectrum typical of a metal-centered radical
L'Auto-vélo : automobilisme, cyclisme, athlétisme, yachting, aérostation, escrime, hippisme / dir. Henri Desgranges
07 avril 19181918/04/07 (A19,N6285)