RESUMO
The letter to the editor presents methodological issues about the search strategy, adequate reporting of meta-analysis, and statistical details of the referred article.
Assuntos
Frutas , Verduras , Humanos , Síndrome Metabólica , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
Surface enhancement Raman scattering (SERS) of two tautomer of thiobarbituric acid was obtained using silver and gold nanoparticles. Large band enhancement in the region of the ν(C=S), ν(C=C), δ(CH2), and δ(CNH) vibrational modes was found. Natural bond analysis of the tautomer species revealed expressive values of charge transfer, principally from lone pair electron orbitals of the S, N, and O atoms. Complete vibrational assignment was done for the two tautomers using the B3LYP/6-311+G (d, p) procedure, band deconvolution analysis, and from a rigorous interpretation of the normal modes matrix. The calculated spectra agree well with the experimental ones.
Assuntos
Tiobarbitúricos/química , Modelos Moleculares , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , EstereoisomerismoRESUMO
Surface-enhanced Raman scattering (SERS) was used to study the interactions of the normal modes of the bis(diethyldithiocarbamate)zinc(II) complex, [Zn(DDTC)2], on nano-structured silver surfaces. The electronic spectrum of this complex was measured and the charge transfer bands were assigned through the TD-PBE1PBE procedure. To see the electronic dispersion, the Mulliken electronic charges were calculated for each normal mode and correlated with the SERS effect. Full assignment of the SERS spectra was also supported by carefully analysis of the distorted geometries generated by the normal modes.
Assuntos
Complexos de Coordenação/química , Ditiocarb/química , Zinco/química , Elétrons , Modelos Moleculares , Espectrofotometria Ultravioleta , Análise Espectral RamanRESUMO
Theoretical and experimental bands have been assigned for the Fourier Transform Infrared (FT-IR) and Fourier Transform Raman (FT-Raman) spectra of the bis-(diethydithiocarbamate)Zn(II) complex, [Zn(DDTC)(2)]. The calculations and spectra interpretation have been based on the DFT/B3LYP method, infrared and Raman second derivative spectra as well as band deconvolution analysis. To assign the metal-ligand normal modes the deviation percentage of the geometrical parameters was used. Results confirms a pseudo tetrahedral structure around the Zn(II) cation. The calculated infrared and Raman spectra has an excellent agreement with the experimental spectra. The Natural Bond Orbital analysis (NBO) was carried out as a way to study the Zn(II) hybridization leading to the pseudo tetrahedral geometry of the framework of the [Zn(DDTC)(2)] complex, and to study also which are the donor NBO and the acceptor NBO in meaningful charge transfer through the Second Order Perturbation Theory Analysis of Fox Matrix in NBO basis.
Assuntos
Complexos de Coordenação/química , Ditiocarb/química , Zinco/química , Modelos Moleculares , Teoria Quântica , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral RamanRESUMO
Theoretical and experimental bands have been assigned for the Fourier Transform Infrared (FT-IR) and FT-Raman spectra of the bis(diethydithiocarbamate)Cu(II) complex, [Cu(DDTC)(2)]. The calculations and spectra interpretation have been based on the DFT/B3LYP method, infrared and Raman second derivative spectra, and band deconvolution analysis. To better assign the metal-ligand normal modes in the spectral region of low energy, the deviation percentage of the geometrical parameters was used, with values from the interpretation of the normal modes of L matrix. Results indicate a planar structure around the Cu(II) cation. The calculated infrared and Raman spectra, based on the proposed geometrical structure of the bis(diethyldithiocarbamate)copper(II) complex, agreed with the experimental spectra.
Assuntos
Complexos de Coordenação/química , Cobre/química , Ditiocarb/química , Complexos de Coordenação/síntese química , Ditiocarb/síntese química , Modelos Moleculares , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral RamanRESUMO
The aspartateguanidoacetatenickel (II) complex, [Ni(Asp)(GAA)], was synthesized and structural analysis was performed by means of the experimental methods: determination of the C, H, N and O contents, thermogravimetry, infrared and Raman spectroscopy. DFT:B3LYP/6-311G(d, p) calculations have been performed giving optimized structure and harmonic vibrational wavenumbers. Second derivative of the FT-infrared, FT-Raman and Surface Raman Enhanced Scattering (SERS) spectra, and band deconvolution analysis were also performed. Features of the FT-infrared, FT-Raman and SERS confirmed theoretical structure prediction. Full assignment of the vibrational spectrum was also supported by a carefully analysis of the distorted geometries generated by the normal modes. The Natural Bond Orbital analysis (NBO) was also carried out as a way to study the Ni (II) hybridization leading to the pseudo planar geometry of the framework, and the extension of the atomic N and O hybrid orbital of the different amino acids in the bond formation. Bands of charge transfer and d-d transitions were assigned in the UV-Vis spectrum.
Assuntos
Ácido Aspártico/química , Elétrons , Modelos Moleculares , Níquel/química , Compostos Organometálicos/química , Teoria Quântica , Análise Espectral Raman , Vibração , Conformação Molecular , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , TermodinâmicaRESUMO
The 2-diazo-5,5-dimethyl-cyclohexane-1,3-dione (3) was synthesized and the FT-IR/Raman spectra were measured with the purpose of obtain a full assignment of the vibrational modes. Singular aspects concerning the -CNN oscillator are discussed in view of two strong bands observed in the region of 2300-2100 cm(-1) in both, Infrared and Raman spectra. The density functional theory (DFT) was used to obtain the geometrical structure and for assisting in the vibrational assignment joint to the traditional normal coordinate analysis (NCA). The observed wavenumbers at 2145 (IR), 2144(R) are assigned as the coupled nu(NN)+nu(CN) vibrational mode with higher participation of the NN stretching. A 2188 cm(-1) (IR) and at 2186 cm(-1) (R) can be assigned as a overtone of one of nu(CC) normal mode or to a combination band of the fundamentals delta(CCH) found at 1169 cm(-1) and the delta (CCN) found at 1017 cm(-1) enhanced by Fermi resonance.
Assuntos
Compostos Azo/química , Cicloexanos/química , Software , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Simulação por Computador , Modelos Químicos , Conformação Molecular , VibraçãoRESUMO
The structure of [Co(gly)(2)(OH)(2)].1.5(H(2)O) was solved by X-ray diffraction. It crystallizes in the space group P-1, with two independent dimmers in the unit cell. The results for the calculated vibrational spectra are in good agreement with the experimental one. The infrared spectrum and ab initio calculations are consistent with the crystallographic results.
Assuntos
Cobalto/química , Glicina/análogos & derivados , Glicina/química , Compostos Organometálicos/síntese química , Carbono/análise , Cristalização/métodos , Glicina/síntese química , Hidrogênio/análise , Modelos Moleculares , Estrutura Molecular , Nitrogênio/análise , Oxirredução , Oxigênio/análise , Análise Espectral/métodos , VibraçãoAssuntos
Anticorpos Antiprotozoários/análise , Entamoeba histolytica/imunologia , Entamebíase/epidemiologia , Imunoglobulina A/análise , Proteínas e Peptídeos Salivares/imunologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Criança , Pré-Escolar , Estudos Transversais , Entamebíase/diagnóstico , Entamebíase/imunologia , Estudos de Avaliação como Assunto , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Prevalência , Saúde da População RuralRESUMO
BACKGROUND: Amebiasis still remains as a major public health problem in the world. It is one of the most common reasons for medical consult. There are more than half a million cases of amebiasis just at the Mexican Institute of the Social Security. There is still a lack of epidemiologic information on amebiasis in Mexico. AIM: To describe the secular trend fro amebiasis and for amebic liver abscess in the Mexican population, as well as in those covered by IMSS Solidaridad. METHOD: An ecologic trend study was carried on. Incidence rate of amebiasis in all of its forms of presentation, and of amebic liver abscess, were plotted against each year for the 1986-1994 period. RESULTS: Amebiasis incidence in all of its forms of presentation showed a stable trend in this period, as it was seen with amebic liver abscess. Amebiasis is more common in the first years of life. On the contrary, amebic liver abscess showed an inverted 'J' pattern; its occurrence is higher in the extreme years of life. Fatality rates have shown a descendent trend. CONCLUSIONS: Amebiasis reflects socioeconomic conditions in Mexico and the fact that Mexican is still an endless culture. There is a need to promote health education, better diagnostic procedures and detection of asymptomatic carriers. Health policies for mothers that are asymptomatic carriers should be reviewed, due to the high rates of amebiasis and amebic liver abscess in children under one year of age.