Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 26
Filtrar
Mais filtros










Base de dados
Tipo de estudo
Intervalo de ano de publicação
1.
Artigo em Inglês | MEDLINE | ID: mdl-34639314

RESUMO

The purpose of this study was to develop criteria for an adolescent circuit exercise program. The subjects of this study were 5268 middle- and high-school students. It consisted of three types of circuit exercise programs which were conducted in the physical education class. In the result of this study, we have found two significant finding. First, there were statistically significant differences by grade level and gender in three types of circuit exercise programs. Second, in order to improve the utilization rate and convenience of various adolescents' physical activity environments and the field of school physical education, the gender of each circuit exercise program was classified and the five-grade evaluation criteria were presented. The criteria for circuit exercise program developed in this study will be utilized for various youth physical activities to contribute to improving health and physical fitness. In addition, physical education teachers are expected to use this criteria as a standard for evaluating the physical fitness level of adolescents.

2.
Artigo em Inglês | MEDLINE | ID: mdl-34299969

RESUMO

The purpose of this study is to compare the physical fitness level of adolescents through a physical fitness assessment and a circuit exercise program. A total of 142 middle school students participated. Physical education class consists of a physical fitness assessment, namely, physical activity promotion system (PAPS), and a circuit exercise program. The PAPS measurements include endurance, flexibility, strength, power, body mass index, and total score. The circuit exercise program consists of twist spine, hand walking, rolling squat, cross knee up, jumping and squat, and level-up pacer. First, there were significant differences in PAPS and circuit exercise program according to grade. Second, there was a significant difference in the results of the circuit exercise program according to the level of each physical fitness variable of PAPS. Third, significant correlations were found in the results of the PAPS and circuit exercise program. The use of a circuit exercise program to measure fitness for adolescents can offer convenience for school physical education and be of value as a measure of physical fitness for adolescents. In addition, the circulatory exercise programs used in this study are thought to be applicable to exercise prescriptions to improve endurance, strength, and BMI.


Assuntos
Exercício Físico , Aptidão Física , Adolescente , Terapia por Exercício , Humanos , Masculino , Educação Física e Treinamento , Instituições Acadêmicas
3.
Artigo em Inglês | MEDLINE | ID: mdl-33036416

RESUMO

Studies found that cardiovascular responses to exercise are enhanced in individuals with obesity and are associated with a greater cardiac output (CO) response compared to normal weight controls. However, the mechanisms underlying these altered responses during dynamic exercise are not clear. We investigated whether the cardiovascular responses mediated by the muscle metaboreflex (MMR) activation are augmented in obese men during both static and dynamic exercise. Twenty males (10 obese (OG) and 10 non-obese (NOG)) were studied. Changes in CO, mean arterial pressure (MAP), and total vascular conductance (TVC) were compared between the two groups during dynamic handgrip exercise (DHE), post-exercise muscular ischemia (PEMI), and dynamic exercise corresponding to 40%, 60% and 80% workloads. Subjects completed 2 min of DHE at 30% of MVC, followed by 2 min of PEMI. MAP, CO, and TVC responses to DHE and dynamic exercise were significantly higher in OG, whereas there were no differences during PEMI. Increases in CO and MAP during mild to heavy dynamic exercise were seen in both groups, but the changes in these variables were greater in the OG. There were no significant differences in TVC between the two groups. Compared to NOG, the augmented blood pressure response to DHE and dynamic exercise in OG was associated with a greater increase in CO. Thus, the augmented CO and MAP responses were not associated with the activation of the MMR. Consequently, additional factors specific to obesity, such as the mechanoreflex, may have been involved.


Assuntos
Exercício Físico , Hemodinâmica , Músculo Esquelético , Obesidade , Pressão Sanguínea , Fenômenos Fisiológicos Cardiovasculares , Exercício Físico/fisiologia , Força da Mão , Frequência Cardíaca , Humanos , Masculino , Músculo Esquelético/fisiologia , Adulto Jovem
4.
Chemosphere ; 97: 135-9, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24280052

RESUMO

A well-type barrier system containing solidified molasses as a reactive medium was developed to promote the indigenous denitrifying activity and to treat nitrate plumes in groundwater. Three slowly released molasses (SRM) barrier systems harboring 60, 120, and 120 SRM rods, which were named System A, B, and C, respectively, were operated to examine nitrate removal efficiency in a pilot-scale sandy tank. These SRM systems induced a consistent removal of nitrate without pore clogging and hydraulic disturbance during the test period. The initial nitrate concentration was 142mgL(-1), and the concentrations decreased by 80%, 84%, and 79% in System A, B, and C, respectively. In particular, System C was inoculated with heterotrophic denitrifiers, but the nitrate removal efficiency was not enhanced compared to System B, probably due to the prior existence of indigenous denitrifiers in the sandy tank. The presence of nitrite reductase-encoding gene (i.e. nirK) at the site was confirmed by denatured gradient gel electrophoresis analysis.


Assuntos
Recuperação e Remediação Ambiental/métodos , Água Subterrânea/química , Melaço , Nitratos/química , Poluentes Químicos da Água/química , Desnitrificação , Nitrito Redutases/análise , Poluentes Químicos da Água/análise
5.
J Korean Neurosurg Soc ; 54(3): 261-4, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24278661

RESUMO

We report a long-term survival case of a primary malignant intracerebral nerve sheath tumor (MINST) occurring in the right frontal lobe of a 13-year old boy. After the gross total resection (GTR), we have performed radiation therapy but it recurred 50 months after the surgery, so the second GTR was performed. Later, second tumor recurrence was found 4 months after the second surgery. Subsequently the third GTR, radiotherapy, and chemotherapy were carried out. At present, the patient has been remaining alive for 77 months without evidence of tumor recurrence. According to the previous reports, the primary MINST is very rare : there are only 8 cases reported. It is also a fast-growing, invasive tumor with poor outcome. This is the first case that had no recurrence for 50 months after the surgery among the reported cases that had been followed up for more than 5 years. It is supposed that a period of recurrence free survival after GTR and low mitotic activity are associated with the patient's prognosis. A GTR followed by adjuvant radiation therapy and chemotherapy will be recommended to patients of MINST.

6.
J Am Chem Soc ; 135(16): 6363-71, 2013 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-23560651

RESUMO

p-Quinodimethane (p-QDM) is a fundamental building block for the design of π-conjugated systems with low band gap and open-shell biradical character. However, synthesis of extended p-QDMs has usually suffered from their intrinsic high reactivity and poor solubility. In this work, benzannulation together with terminal cyano-substitution was demonstrated to be an efficient approach for the synthesis of a series of soluble and stable tetracyano-oligo(N-annulated perylene)quinodimethanes nPer-CN (n = 1-6), with the longest molecule having 12 para-linked benzenoid rings! The geometry and electronic structures of these oligomers were investigated by steady-state and transient absorption spectroscopy, nuclear magnetic resonance, electron spin resonance, superconducting quantum interference device, and FT Raman spectroscopy assisted by density functional theory calculations. They showed tunable ground states, varying from a closed-shell quinoidal structure for monomer, to a singlet biradical for dimer, trimer, and tetramer, and to a triplet biradical for pentamer and hexamer. Large two-photon absorption cross-section values were observed in the near-infrared range, which also exhibited a clear chain-length dependence.

7.
Nat Chem ; 5(1): 15-20, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23247172

RESUMO

Proton-coupled electron transfer (PCET) processes are among the most important phenomena that control a variety of chemical and biological transformations. Although extensively studied in a variety of natural systems and discrete metal complexes, PCET mechanisms are less well codified in the case of purely organic compounds. Here we report that a planar ß,ß'-phenylene-bridged hexaphyrin (1.0.1.0.1.0), a 24 π-electron antiaromatic species termed rosarin, displays unique redox reactivity on protonation. Specifically, treatment with acid (for example, HI) yields a 26 π-electron aromatic triprotonated monocationic species that is produced spontaneously via an intermediate-but stable-25 π-electron non-aromatic triprotonated monoradical dication. This latter species is also produced on treatment of the original 24 π-electron antiaromatic starting material with HCl or HBr. The stepwise nature of the proton-coupled reduction observed in the planar rosarin stands in marked contrast to that seen for non-annulated rosarins and other ostensibly antiaromatic expanded porphyrinoids.


Assuntos
Dissacarídeos/química , Prótons , p-Fluorfenilalanina/química , Cristalografia por Raios X , Espectroscopia de Ressonância Magnética , Conformação Molecular , Oxirredução
8.
Chem Asian J ; 8(1): 178-90, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23097353

RESUMO

We have demonstrated that the iridium-catalyzed direct borylation of hexa-peri-hexabenzocoronene (HBC) enables regioselective introduction of boryl groups to the para-, ortho-, and meta-substituted HBCs in high yields. The boryl groups have been transformed into various functionalities such as hydroxy, cyano, ethynyl, and amino groups. We have elucidated that the substituents significantly influence the photophysical properties of HBCs to enhance fluorescence quantum yields. DFT calculations revealed that the origin of the substituent effect is the lift in degeneracy in the frontier orbitals by an interaction with electron-donating and electron-withdrawing substituents at the para- and ortho-positions. The change in molecular orbitals results in an increase of the transition probability from the S(0)→S(1) states. In addition, the two-photon absorption cross-section values of para-substituted HBCs are significantly larger than those of ortho- and meta-substituted HBCs.

9.
Angew Chem Int Ed Engl ; 51(52): 13105-8, 2012 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-23161798

RESUMO

Singly twisted Möbius antiaromatic [34]heptaphyrin A and doubly twisted Hückel aromatic [34]heptaphyrin B were formed by a phosphorus insertion reaction. A rearranges thermally to give the more stable B with P=O migration from NNN to NNC, and thus A is a rare case of a kinetically controlled Möbius antiaromatic molecule.

10.
Angew Chem Int Ed Engl ; 51(50): 12459-63, 2012 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-23124801

RESUMO

Stable antiaromatic expanded porphyrins were designed by the judicious implementation of meso-imidazolyl groups, which cause stabilization through the creation of a hydrogen-bonding network that overcomes antiaromatic electronic destabilization. Both the [28]hexaphyrin 1 and the [36]octaphyrin 2, which contain imidazolyl groups at two opposite meso positions, are shown to be stable Hückel antiaromatic species.

11.
Chemistry ; 18(49): 15838-44, 2012 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-23070729

RESUMO

meso-Hexakis(pentafluorophenyl)-substituted neutral hexaphyrin with a 26π-electronic circuit can be regarded as a real homolog of porphyrin with an 18π-electronic circuit with respect to a quite flat molecular structure and strong aromaticity. We have investigated additional aromaticity enhancement of meso-hexakis(pentafluorophenyl)[26]hexaphyrin(1.1.1.1.1.1) by deprotonation of the inner N-H groups in the macrocyclic molecular cavity to try to induce further structural planarization. Deprotonated mono- and dianions of [26]hexaphyrin display sharp B-like bands, remarkably strong fluorescence, and long-lived singlet and triplet excited-states, which indicate enhanced aromaticity. Structural, spectroscopic, and computational studies have revealed that deprotonation induces structural deformations, which lead to a change in the main conjugated π-electronic circuit and cause enhanced aromaticity.

12.
Chemistry ; 18(45): 14329-41, 2012 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-23008189

RESUMO

The synthesis, characterization, photophysical properties, and theoretical analysis of a series of tetraaza porphyrin analogues (H-Pn: n=1-4) containing a dipyrrin subunit and an embedded 1,10-phenanthroline subunit are described. The meso-phenyl-substituted derivative (H-P1) interacts with a Mg(2+) salt (e.g., MgCl(2), MgBr(2), MgI(2), Mg(ClO(4))(2), and Mg(OAc)(2)) in MeCN solution, thereby giving rise to a cation-dependent red-shift in both the absorbance- and emission maxima. In this system, as well as in the other H-Pn porphyrin analogues used in this study, the four nitrogen atoms of the ligand interact with the bound magnesium cation to form Mg(2+)-dipyrrin-phenanthroline complexes of the general structure MgX-Pn (X=counteranion). Both single-crystal X-ray diffraction analysis of the corresponding zinc-chloride derivative (ZnCl-P1) and fluorescence spectroscopy of the Mg-adducts that are formed from various metal salts provide support for the conclusion that, in complexes such as MgCl-P1, a distorted square-pyramidal geometry persists about the metal cation wherein a chloride anion acts as an axial counteranion. Several analogues (HPn) that contain electron-donating and/or electron-withdrawing dipyrrin moieties were prepared in an effort to understand the structure-property relationships and the photophysical attributes of these Mg-dipyrrin complexes. Analysis of various MgX-Pn (X=anion) systems revealed significant substitution effects on their chemical, electrochemical, and photophysical properties, as well as on the Mg(2+)-cation affinities. The fluorescence properties of MgCl-Pn reflected the effect of donor-excited photoinduced electron transfer (d-PET) processes from the dipyrrin subunit (as a donor site) to the 1,10-phenanthroline acceptor subunit. The proposed d-PET process was analyzed by electron paramagnetic resonance (EPR) spectroscopy and by femtosecond transient absorption (TA) spectroscopy, as well as by theoretical DFT calculations. Taken together, these studies provide support for the suggestion that a radical species is produced as the result of an intramolecular charge-transfer process, following photoexcitation. These photophysical effects, combined with a mixed dipyrrin-phenanthroline structure that is capable of effective Mg(2+)-cation complexation, lead us to suggest that porphyrin-inspired systems, such as HPn, have a role to play as magnesium-cation sensors.


Assuntos
Complexos de Coordenação/química , Magnésio/química , Fenantrolinas/química , Porfirinas/química , Cloretos/química , Complexos de Coordenação/síntese química , Cristalografia por Raios X , Espectroscopia de Ressonância de Spin Eletrônica , Íons/química , Ligantes , Conformação Molecular , Teoria Quântica , Espectrofotometria , Compostos de Zinco/química
13.
J Am Chem Soc ; 134(40): 16540-3, 2012 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-22988981

RESUMO

Two types of thieno-bridged porphyrins were synthesized by incorporating a thiophene group across their meso and ß positions with different directions of the thiophene ring to investigate the aromaticity of these porphyrins with extended π-systems. The 2,3-thieno-bridged porphyrin showed a larger antiaromatic contribution than did the 3,4-thieno-bridged porphyrin. In the former, the antiaromatic contribution is based on a 20-π-electron conjugated circuit. The two thieno-bridged porphyrins were characterized by calculations of nucleus-independent chemical shift and anisotropy of the induced current density as well as by X-ray crystallography, NMR spectroscopy, UV-vis-NIR absorption spectroscopy, electrochemical studies, time-resolved excited-state analysis, and two-photon absorption cross section measurements. Chemical derivatization of the 2,3-thieno-bridged porphyrin was also demonstrated.

14.
J Am Chem Soc ; 134(36): 14913-22, 2012 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-22908899

RESUMO

Polycyclic aromatic hydrocarbons with an open-shell singlet biradical ground state are of fundamental interest and have potential applications in materials science. However, the inherent high reactivity makes their synthesis and characterization very challenging. In this work, a convenient synthetic route was developed to synthesize two kinetically blocked heptazethrene (HZ-TIPS) and octazethrene (OZ-TIPS) compounds with good stability. Their ground-state electronic structures were systematically investigated by a combination of different experimental methods, including steady-state and transient absorption spectroscopy, variable temperature NMR, electron spin resonance (ESR), superconducting quantum interfering device (SQUID), FT Raman, and X-ray crystallographic analysis, assisted by unrestricted symmetry-broken density functional theory (DFT) calculations. All these demonstrated that the heptazethrene derivative HZ-TIPS has a closed-shell ground state while its octazethrene analogue OZ-TIPS with a smaller energy gap exists as an open-shell singlet biradical with a large measured biradical character (y = 0.56). Large two-photon absorption (TPA) cross sections (σ((2))) were determined for HZ-TIPS (σ((2))(max) = 920 GM at 1250 nm) and OZ-TIPS (σ((2))(max) = 1200 GM at 1250 nm). In addition, HZ-TIPS and OZ-TIPS show a closely stacked 1D polymer chain in single crystals.


Assuntos
Hidrocarbonetos Policíclicos Aromáticos/química , Teoria Quântica , Cristalografia por Raios X , Cinética , Modelos Moleculares , Estrutura Molecular
15.
J Am Chem Soc ; 134(35): 14513-25, 2012 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-22889277

RESUMO

Stable open-shell polycyclic aromatic hydrocarbons (PAHs) are of fundamental interest due to their unique electronic, optical, and magnetic properties and promising applications in materials sciences. Chichibabin's hydrocarbon as a classical open-shell PAH has been investigated for a long time. However, most of the studies are complicated by their inherent high reactivity. In this work, two new stable benzannulated Chichibabin's hydrocarbons 1-CS and 2-OS were prepared, and their electronic structure and geometry in the ground state were studied by various experiments (steady-state and transient absorption spectra, NMR, electron spin resonance (ESR), superconducting quantum interference device (SQUID), FT Raman, X-ray crystallographic etc.) and density function theory (DFT) calculations. 1-CS and 2-OS exhibited tunable ground states, with a closed-shell quinoidal structure for 1-CS and an open-shell biradical form for 2-OS. Their corresponding excited-state forms 1-OS and 2-CS were also chemically approached and showed different decay processes. The biradical 1-OS displayed an unusually slow decay to the ground state (1-CS) due to a large energy barrier (95 ± 2.5 kJ/mol) arising from severe steric hindrance during the transition from an orthogonal biradical form to a butterfly-like quinoidal form. The quick transition from the quinoidal 2-CS (excited state) to the orthogonal biradicaloid 2-OS (ground state) happened during the attempted synthesis of 2-CS. Compounds 1-CS and 2-OS can be oxidized into stable dications by FeCl(3) and/or concentrated H(2)SO(4). The open-shell 2-OS also exhibited a large two-photon absorption (TPA) cross section (760 GM at 1200 nm).

16.
Angew Chem Int Ed Engl ; 51(39): 9856-9, 2012 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-22865692

RESUMO

Gold standard: A bis(Au(III)) complex containing the title compound was prepared and characterized (see scheme; DDQ=2,3-dichloro-5,6-dicyano-1,4-benzoquinone, Tf=trifluoromethanesulfonyl). Owing to the effective conjugative network over the flat and elongated rectangular molecular frame, this complex displays a remarkably red-shifted and sharp Q-band-like band at 1467 nm, multiple reversible redox potentials, and a large TPA cross-section value.

17.
Chem Commun (Camb) ; 48(62): 7684-6, 2012 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-22739786

RESUMO

4-tert-Butylphenyl-substituted and fused quinoidal porphyrins 1 and 2 are prepared for the first time. They show (1) intense one-photon absorption in the far-red/near-infrared region, (2) enhanced two-photon absorption compared with aromatic porphyrin monomers, and (3) amphoteric redox behavior. Their geometry and electronic structure are studied by DFT calculations.

18.
Chem Commun (Camb) ; 48(54): 6785-7, 2012 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-22643454

RESUMO

5,10,15,20-Tetrakis(pentafluorophenyl) [22]pentaphyrin(1.1.1.1.1) 7 was synthesised and its bis-rhodium(I) complex 12 has been revealed to be a non-fused, yet planar pentaphyrin with an inverted pyrrole. Both 7 and 12 are aromatic, showing sharp Soret-like bands and diatropic ring currents.

19.
Chem Asian J ; 7(8): 1811-6, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22615269

RESUMO

Hexakis(pentafluorophenyl)-substituted meso-meso-linked Zn(II)-diporphyrin (9), which was prepared by the acid-catalyzed cross-condensation of 1,1,2,2-tetrapyrroethane (5) with dipyrromethane dicarbinol (6), was converted into meso-meso,ß-ß,ß-ß triply linked Zn(II)-diporphyrin 3 by oxidation with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) and Sc(OTf)(3). Beside the red-shifted absorption spectrum and split first oxidation potential that are common to the triply-linked Zn(II)-diporphyrins, diporphyrin 3 exhibited considerably improved chemical stability owing to a lowered HOMO and good solubility in common organic solvents. The two-photon absorption (TPA) cross-section and S(1)-state lifetime of compound 3 were 1700 GM and 3.3 ps, respectively.

20.
Chemistry ; 18(19): 5853-9, 2012 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-22461174

RESUMO

A new member of the cyclo[n]pyrrole class of expanded porphyrins could be prepared from the corresponding thiophene-containing terpyrrole precursor through use of a mild electrochemical oxidative procedure. The isolated macrocycle, featuring nine heterocyclic subunits directly connected through their α,α'-positions, is the largest cyclo[n]pyrrole derivative reported to date (see figure).

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...