Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 58
Filtrar
1.
J Phys Chem A ; 119(9): 1600-8, 2015 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-25325400

RESUMO

The molecular structure of 1,2-bis(trifluoromethyl)-1,1,2,2-tetramethyldisilane has been determined in three different phases (solid, liquid, and gas) using various spectroscopic and diffraction techniques. Both the solid-state and gas-phase investigations revealed only one conformer to be present in the sample analyzed, whereas the liquid phase revealed the presence of three conformers. The data have been reproduced using computational methods and a rationale is presented for the observation of three conformers in the liquid state.

2.
J Environ Health ; 76(6): 156-61, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24645427

RESUMO

Combined exposure to secondhand smoke (SHS) and radon increases lung cancer risk 10-fold. The authors assessed the feasibility and impact of a brief home screening and environmental feedback intervention to reduce radon and SHS (Freedom from Radon and Smoking in the Home [FRESH]) and measured perceived risk of lung cancer and synergistic risk perception (SHS x radon). Participants (N = 50) received home radon and SHS kits and completed baseline surveys. Test results were shared using an intervention guided by the Teachable Moment Model. Half of the participants completed online surveys two months later. Most (76%) returned the radon test kits; 48% returned SHS kits. Of the returned radon test kits, 26% were >4.0 pCi/L. Of the returned SHS kits, 38% had nicotine > .1 microg/m3. Of those with high radon, more than half had contacted a mitigation specialist or planned contact. Of those with positive air nicotine, 75% had adopted smoke-free homes. A significant increase occurred in perceived risk for lung cancer and synergistic risk perception after FRESH.


Assuntos
Atitude Frente a Saúde , Monitoramento Ambiental/métodos , Habitação/estatística & dados numéricos , Radônio/análise , Poluição por Fumaça de Tabaco/análise , Adulto , Feminino , Humanos , Neoplasias Pulmonares/etiologia , Neoplasias Pulmonares/psicologia , Masculino , Pessoa de Meia-Idade , Radônio/intoxicação , Risco , Fumar , Inquéritos e Questionários , Poluição por Fumaça de Tabaco/efeitos adversos
3.
Inorg Chem ; 52(8): 4502-8, 2013 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-23541164

RESUMO

Gas-phase structure determinations have been performed for arachno-4,6-(CH2)2B7H9 and arachno-4,6-S2B7H9 by combining quantum-chemical calculations and gas electron diffraction (GED) data. In addition, the monoanion derivatives of each of the aforementioned species have been studied using ab initio calculations. In all cases, comparison with experimental (11)B NMR chemical shifts have been achieved by calculating the appropriate NMR chemical shifts using GIAO-MP2 methods and the IGLO-II basis set for various geometries, both experimental and calculated. The NMR parameters calculated for the geometry obtained from the SARACEN GED refinement appeared to be quite reasonable, and in general, the fit between theoretical and experimental δ((11)B) NMR was found to be consistently good for all four species investigated.

4.
Inorg Chem ; 51(5): 3324-31, 2012 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-22332822

RESUMO

The molecular structures of the vapors produced on heating dimethylalkoxygallanes of the type [Me(2)Ga(OR)](2) have been determined by gas electron diffraction and ab initio molecular orbital calculations. In the solid state [Me(2)Ga(OCH(2)CH(2)NMe(2))](2) (1) and [Me(2)Ga(OCH(2)CH(2)OMe)](2) (2) adopt dimeric structures, although only the monomeric forms [Me(2)Ga(OCH(2)CH(2)NMe(2))] (1a) and [Me(2)Ga(OCH(2)CH(2)OMe)] (2a) were observed in the gas phase. For comparison the structure of the vapor produced on heating [Me(2)Ga(O(t)Bu)](2) (3) was also studied by gas electron diffraction. In contrast to 1 and 2, compound 3 is dimeric in the gas phase, as well as in the solid state. The gas-phase structures of 1a and 2a exhibit five-membered rings formed by a dative bond between Ga and the donor atom (N or O) from the donor-functionalized alkoxide. In 3 there is no possibility of a monomeric structure being stabilized by the formation of such a dative bond since only a monofunctional alkoxide is present in the molecule.

5.
Inorg Chem ; 50(7): 2988-94, 2011 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-21384904

RESUMO

The equilibrium molecular structure of Si(8)O(12)(OSiMe(3))(8) has been determined in the gas phase by electron diffraction (GED). With OSi-containing substituents on the cage silicon atoms, this molecule contains a moiety, which would, if reproduced in a periodic manner, yield a zeolite-type structure. Extensive ab initio calculations were used to identify two conformers of this molecule, with D(4) and D(2) point-group symmetries; the D(4)-symmetric conformer was approximately 1.2 kJ mol(-1) lower in energy. With 132 atoms in each conformer, this is one of the largest studies to be undertaken using gas electron diffraction. Semiempirical molecular-dynamics (SE-MD) calculations were used to give amplitudes of vibration, vibrational distance corrections (differences between interatomic distances in the equilibrium structure and the vibrationally averaged distances that are given directly by the diffraction data), and anharmonic constants. The structure of Si(8)O(12)(CHCH(2))(8) has also been determined by GED. Calculations showed that the vinyl groups are fairly unhindered and rotate between three minimum-energy positions. Ultimately, all possible combinations of the vinyl groups in these low-energy positions were accounted for in the GED model.


Assuntos
Compostos de Organossilício/química , Gases/química , Modelos Moleculares , Simulação de Dinâmica Molecular , Estrutura Molecular , Teoria Quântica
6.
Nicotine Tob Res ; 12(6): 665-8, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20410143

RESUMO

INTRODUCTION: Smoking rooms have been installed in some airports to allow indoor smoking. There have been few field studies to measure fine particle leakage in operational smoking rooms. The objective of the research was to assess air quality inside and outside the 4 smoking rooms located within a medium-sized, regional commercial airport. METHODS: Particulate matter less than 2.5-microm (PM(2.5)) concentrations were simultaneously measured inside and outside the 4 smoking rooms in the airport and in the public lobby. The monitoring was conducted during normal hours of operation. Numbers of people and smokers were counted. The airport had separate ventilation systems for all 4 rooms checked by the airport prior to monitoring, and they were operating properly. RESULTS: Although there were few smokers in each room, average PM(2.5) concentrations inside the smoking rooms were significantly higher than the National Ambient Air Quality Standard for 24 hr (35 microg/m(3)). Fine particles from secondhand smoke (SHS) leaked to the outside in 3 of the 4 smoking rooms, exposing workers and the public. DISCUSSION: Although the ventilation systems in the smoking rooms were operating properly, fine particles from SHS leaked to the surrounding smoke-free areas in the airport. Indoor space inside airports should be completely nonsmoking, and enclosed smoking rooms are not recommended.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Monitoramento Ambiental , Logradouros Públicos , Poluição por Fumaça de Tabaco/análise
7.
J Phys Chem A ; 114(41): 11022-6, 2010 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-20873860

RESUMO

When refining structures using gas electron diffraction (GED) data, assumptions are often made in order to reduce the number of required geometrical parameters. Where these relate to light, peripheral atoms there is little effect on the refined heavy-atom structure, which is well defined by the GED data. However, this is not the case when heavier atoms are involved. We have determined the gas-phase structure of perfluoro(methylcyclohexane), C(6)F(11)CF(3), using three different refinement methods and have shown that our new method, which makes use of both MP2 and molecular mechanics (MM) calculations to restrain the peripheral-atom geometry, gives a realistic structure without the need for damaging constraints. Only the conformer with the CF(3) group in an equatorial position was considered, as ab initio calculations showed this to be 25 kJ mol(-1) lower in energy than the axial conformer. Refinements combining both high-level and low-level calculations to give constraints were superior both to those based only on molecular mechanics and to those in which assumptions about the geometry were imposed.

8.
J Am Chem Soc ; 131(6): 2231-43, 2009 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-19170515

RESUMO

The structures of the molecules methylamine-borane, MeH(2)N.BH(3), and dimethylamine-borane, Me(2)HN.BH(3), have been investigated by gas-phase electron diffraction (GED) and quantum chemical calculations. The crystal structures have also been determined for methylamine-, dimethylamine-, and trimethylamine-borane, Me(n)H(3-n)N.BH(3) (n = 1-3); these are noteworthy for what they reveal about the intermolecular interactions and, particularly, the N-H...H-B dihydrogen bonding in the cases where n = 1 or 2. Hence, structures are now known for all the members of the ammonia- and amine-borane series Me(n)H(3-n)N.BH(3) (n = 0-3) in both the gas and solid phases. The structural variations and energetics of formation of the gaseous adducts are discussed in relation to the basicity of the Me(n)H(3-n)N fragment. The relative importance of secondary interactions in the solid adducts with n = 0-3 has been assessed by the semi-classical density sums (SCDS-PIXEL) approach.

9.
Inorg Chem ; 48(5): 2289-99, 2009 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-19166314

RESUMO

The gas-phase (electron diffraction) and solid-state (X-ray) structures of W(NBut)2(NHBut)2 (1) have been determined. In the gas phase, 1 adopts both C1 and C2 conformations in a 69:31 ratio. The solid-state structure is disordered over two equal sites, both showing approximate C2 conformation as in the gas phase; the imido and amido centers are, however, clearly distinguished. Compound 1 has been used to synthesize novel heterobimetallic derivatives W(NBut)4[Rh(COD)]2 (3) and W(NBut)4[Pd(eta3-C3H5)]2 (4) via the dilithiated intermediate Li2[W(NBut)4] (2). In both cases, the [W(NBut)4] moiety bridges the two organometallic fragments. Reaction of 1 with Me2Zn has produced [Me(tBuN)W(mu-NBut)2ZnMe(NH2But)] (5). The structures of 3, 4, and 5 have been determined. Thermal decomposition of 4 under an autogenerated pressure at 700 degrees C has formed the hitherto uncharacterized bimetallic alloy WPd2.

10.
Inorg Chem ; 48(17): 8603-12, 2009 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-19663455

RESUMO

The molecular structures of allyl-, allenyl-, propargyl-, vinyl-, ethynyl-, phenyl-, benzyl-, and chloromethyl-phosphine have been determined from gas-phase electron diffraction data employing the SARACEN method. The experimental geometric parameters are compared with those obtained using ab initio calculations performed at the MP2 level using both Pople-type basis sets and the correlation-consistent basis sets of Dunning. The structure and conformational behavior of each molecule have been analyzed and, where possible, comparisons made to the analogous amine. For systems with multiple conformers, differences in the CCP bond angle of approximately 5 degrees between conformers are common. Trends in the key parameters are identified and compared with those found in similar systems.


Assuntos
Simulação por Computador , Elétrons , Modelos Químicos , Fosfinas/química , Teoria Quântica , Aminas/química , Gases/química , Modelos Moleculares , Estrutura Molecular , Fosfinas/síntese química
11.
Nicotine Tob Res ; 11(4): 381-6, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19346510

RESUMO

INTRODUCTION: Smoke-free air laws have been implemented in many Kentucky communities to protect the public from the harmful effects of secondhand smoke exposure. The impact of different strengths of smoke-free air laws on indoor air quality was assessed. METHODS: Indoor air quality in hospitality venues was assessed in seven communities before and after comprehensive smoke-free air laws and in two communities only after partial smoke-free air laws. One community was measured three times: before any smoke-free air law, after the initial partial law, and after the law was strengthened to cover all workplaces and public places with few exemptions. Real-time measurements of particulate matters with 2.5 mum aerodynamic diameter or smaller (PM(2.5)) were obtained. RESULTS: When comprehensive smoke-free air laws were implemented, indoor PM(2.5) concentrations decreased significantly from 161 to 20 microg/m3. In one community that implemented a comprehensive smoke-free law after initially passing a partial law, indoor PM(2.5) concentrations were 304 microg/m3 before the law, 338 microg/m3 after the partial law, and 9 microg/m3 after the comprehensive law. DISCUSSION: The study clearly demonstrated that partial smoke-free air laws do not improve indoor air quality. A significant linear trend indicated that PM(2.5) levels in the establishments decreased with fewer numbers of burning cigarettes. Only comprehensive smoke-free air laws are effective in reducing indoor air pollution from secondhand tobacco smoke.


Assuntos
Poluição do Ar em Ambientes Fechados/prevenção & controle , Material Particulado/análise , Fumar/legislação & jurisprudência , Poluição do Ar em Ambientes Fechados/análise , Humanos , Kentucky , Tamanho da Partícula
12.
J Phys Chem A ; 113(17): 5195-204, 2009 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-19298067

RESUMO

The molecular structure of trimethylgermane has been determined by gas electron diffraction experiments. Infrared spectra for the gaseous, liquid, and solid phases were also recorded. Parallel and perpendicular polarized Raman spectra for the liquid were measured to obtain depolarization values. The experimental studies were supported by a series of computational calculations using HF, B3LYP, and MP2 methods and a variety of basis sets. The force fields obtained from density functional theory using both B3LYP/6-31G* and B3LYP/6-311+G** were scaled with both Pulay's SQM methodology and Yoshida's WLS procedure to simulate the vibrational spectra and assist in the assignment of fundamental bands. The Raman intensities were obtained from polarizability derivatives. The vibrational spectra of trimethylgermane were completely assigned on the basis of the experimental data and the theoretical prediction of vibrational frequencies and intensities.


Assuntos
Simulação por Computador , Modelos Químicos , Compostos Organometálicos/química , Elétrons , Gases/química , Estrutura Molecular , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Análise Espectral Raman/métodos
13.
J Chem Phys ; 131(21): 214303, 2009 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-19968344

RESUMO

The molecular structure and conformational properties of S-ethyl trifluorothioacetate, CF(3)COSCH(2)CH(3), were determined in the gas phase by electron diffraction and vibrational spectroscopy (IR and Raman). The experimental investigations were supplemented by ab initio (Moller Plesset of second order) and density functional theory quantum chemical calculations at different levels of theory. Both experimental and theoretical methods reveal two structures with C(s) (anti, anti) and C(1) (anti, gauche) symmetries, although there are disagreements about which is more stable. The electron diffraction intensities are best interpreted with a mixture of 51(3)% anti, anti and 49(3)% anti, gauche conformers. This conformational preference was studied using the total energy scheme and the natural bond orbital scheme. In addition, the infrared spectra of CF(3)COSCH(2)CH(3) are reported for the gas, liquid and solid phases as well as the Raman spectrum of the liquid. Using calculated frequencies as a guide, evidence for both C(s) and C(1) structures is obtained in the IR spectra. Harmonic vibrational frequencies and scaled force fields have been calculated for both conformers.


Assuntos
Fluoracetatos , Modelos Moleculares , Conformação Molecular , Teoria Quântica , Espectrofotometria Infravermelho , Análise Espectral Raman , Ácido Trifluoracético/química
14.
Chem Commun (Camb) ; (25): 2618-20, 2007 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-17579757

RESUMO

The vapour produced upon mild heating of hexa-tert-butyldisilane (superdisilane) has been studied by gas electron diffraction and ab initio molecular orbital calculations; the disilane is not observed in the vapour, and the observed radical structure is not the lowest energy structure predicted ab initio.

15.
Artigo em Inglês | MEDLINE | ID: mdl-15820874

RESUMO

The molecular structure and conformation of 1,1,1,4,4,4-hexachloro-1,4-disilabutane in the gas-phase have been determined by electron diffraction and computational methods. The lowest-energy conformation has the trichlorosilyl groups anti to one another. The gauche conformation also has a shallow potential minimum, but lies about 19 kJ mol-1 above the anti form. Calculations on related butane derivatives, in which terminal methyl groups have been replaced by CCl3, SiH3 and SiCl3 groups, reveal that the conformational preferences are primarily caused by steric interactions between the terminal groups, and that it is the presence of chlorine atoms that destabilises gauche conformations. The electronegativity of the chlorine atoms has only small effects, mainly limited to the SiCl bond lengths.


Assuntos
Butanos/química , Silanos/química , Carbono/química , Cloro/química , Elétrons , Hidrogênio/química , Modelos Teóricos , Conformação Molecular , Silício/química
16.
J Org Chem ; 62(9): 2767-2773, 1997 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-11671638

RESUMO

The molecular structure of 3,4-dimethylenehexa-1,5-diene ([4]dendralene), C(8)H(10), has been determined in the gas phase. A single conformer with C(2) symmetry, having two almost planar, anti butadiene groups orientated with a dihedral angle C(2)C(3)C(4)C(5) of 71.7(19) degrees, is detected by electron diffraction employing flexible restraints derived from ab initio computations. Other experimental structural parameters (r(alpha)/pm, angle(alpha)/ degrees ) are: C(1)=C(2) 133.4(1), C(3)=C(7) (not in main chain) 134.0(1), C(2)-C(3) 147.4(2), C(3)-C(4) 149.6(3), C(1)C(2)C(3) 124.4(3), C(2)C(3)C(4) 119.2(5), C(4)C(3)C(7) 117.6(7), and C(7)C(3)C(2)C(1) -174.8(28). Ab initio computations at the MP2/6-311G level predict that the vapor consists of ca. 90% of the conformer found experimentally, the other 10% comprising four other conformers.

17.
Inorg Chem ; 37(11): 2687-2692, 1998 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-11670404

RESUMO

The gas-phase structure of chlorodifluoronitrosomethane, CClF(2)NO, has been determined by electron diffraction and calculated ab initio. Theoretically, CClF(2)NO is predicted to consist of two conformers having C(s)() (phi = 0 degrees ) and C(1) (phi = 105 degrees ) symmetry, which are near degenerate in energy, DeltaE = 1.1 kJ mol(-1) [TZ2P/MP2 + ZPE(DZP/MP2)], and separated by a barrier of around 1 kJ mol(-1). Equivalent C(1) conformers are predicted to be connected by a barrier of around 5-10 kJ mol(-1). The low predicted barriers to interconversion of the two conformers suggest that the rotation of the nitroso group can be regarded as being barely restricted over most values of the torsional angle at room temperature. This conclusion is supported by the gas-phase electron diffraction data, for which a dynamic model employing 11 conformations was needed to obtain an accurate fit to the experimental data. The final refined values of structural parameters for the two conformers (C(s)()/C(1)) are (r(alpha)/pm,<(alpha)/deg) as follows: C(1)-N(2) 156.7(5)/155.9(5), N(2)-O(3) 117.5(3)/117.9(3), C(1)-Cl(4) 173.9(2)/174.2(2), C(1)-F 132.0(2)/132.1(2) and 131.0(2), C(1)-N(2)-O(3) 110.8(12)/110.7(12), N(2)-C(1)-Cl(4) 117.5(5)/108.9(5), N(2)-C(1)-F 103.7(2)/104.2(2) and 111.6(2), Cl(4)-C(1)-N(2)-F 123.6(14)/119.2(14) and 123.7(14).

18.
Inorg Chem ; 36(6): 1048-1054, 1997 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-11669667

RESUMO

The molecular structure of trifluorophosphine tetraborane(8), B(4)H(8)PF(3), has been studied in the gas phase by electron diffraction. The experimental data can be fitted using a model which represents the gas as consisting solely of the endo conformer with C(s)() symmetry, the PF(3) group staggered with respect to the B(1)-H(1) bond. Important experimental structural parameters (r(alpha) degrees ) are r[B(1)-B(2)] (hinge-wing) = 184.7(9) pm, r[B(1)-B(3)] (hinge-hinge) = 172.2(12) pm, r[B(2)-B(3)] = 179.9(10) pm,r[B(1)-P] = 179.8(9) pm, and r(P-F) (mean) = 152.8(1) pm; B(3)B(1)P = 131.6(11) degrees, and the dihedral ("butterfly") angle between the planes B(1)B(2)B(3) and B(1)B(4)B(3) is 133.9(23) degrees. These values agree well with the ab initio (MP2/TZP level) optimized molecular geometry for the endo conformer; at the MP2/TZP//MP2/TZP + ZPE(HF/6-31G) level, the exo conformer is predicted to represent ca. 2% of the compound vapor, consistent with the experimental (11)B NMR solution spectrum. The experimental and theoretical geometries are supported by comparison of the calculated (IGLO) (11)B NMR chemical shifts with the experimental NMR data.

19.
Inorg Chem ; 35(6): 1701-1708, 1996 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-11666394

RESUMO

The compound 1-phenyl-1,2-dicarba-closo-dodecaborane(12), 1-C(6)H(5)-1,2-closo-C(2)B(10)H(11) (1), has been synthesized and characterized by a complete assignment of its (11)B NMR spectrum via (11)B{(1)H}/(11)B{(1)H} (COSY), (1)H{(11)B(selective)} and (1)H{(11)B}/(1)H{(11)B} (COSY) spectroscopy. An electron- and X-ray diffraction investigation of 1, complemented by ab initio calculations, has been undertaken. The gas-phase electron-diffraction (GED) data can be fitted by several models describing conformations which differ in the position of the phenyl ring with respect to the carborane cage. Local symmetries ofC(2)(v)() and D(6)(h)() for the 1,2-C(2)B(10) and C(6) moieties, respectively, were adopted in the GED model in order to simplify the problem. In addition, constraints among the close-lying C-C and B-B bonds were employed. However, even though such simplifications led to satisfactory refinements (R(G) = 0.069-0.071), a unique, definitive solution could not be gained. The (C-C)(mean), (C-B)(mean) and (B-B)(mean) bond lengths,r(a), are ca. 1.44, 1.72, and 1.78 Å, respectively. The C(6) hexagon, with r(a)(C-C) = ca. 1.394 Å, either eclipses the C(1)-C(2) vector (overall C(s)() symmetry) or more or less eclipses the C(1)-B(4) cluster bond (overall C(1) symmetry). In contrast, in the solid at 199 K, the ring lies at a position intermediate between the two GED positions, as determined by X-ray crystallography [C(8)H(16)B(10), monoclinic P2(1)/a: a = 12.047(3) Å, b = 18.627(4) Å, c = 12.332(5) Å, beta = 110.09(4) degrees, Z = 8]. The C-B distances span the range 1.681(6)-1.743(5) Å, and B-B lengths lie between 1.756(6) and 1.795(6) Å. A similar conformation was found for the theoretical (RHF/6-31G level) structure which was fully optimized in C(1) symmetry. The r(e) distances are consistent with the dimensions derived in the experimental studies. IGLO calculations of the (11)B chemical shifts, in addition to SCF single-point energies of the GED structures, further support these observations.

20.
Inorg Chem ; 35(24): 6952-6958, 1996 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-11666872

RESUMO

The structures of gaseous CH(3)AsF(2) and (CH(3))(2)AsF have been determined by electron diffraction incorporating vibrational amplitudes derived from ab initio force fields scaled by experimental frequencies and, for the difluoride, restrained by microwave constants. The following parameters (r(alpha) degrees structure, distances in pm, angles in degrees) have been determined for CH(3)AsF(2): r(As-C) = 194.6(4), r(As-F) = 173.1(1), angleCAsF = 95.2(1), angleFAsF = 97.0(1). For (CH(3))(2)AsF structural refinement gives r(As-C) = 195.1(1), r(As-F) = 175.4(1), angleCAsF = 95.3(5), and angleCAsC = 96.9(8). For the series (CH(3))(3)As, (CH(3))(2)AsF, CH(3)AsF(2), and AsF(3), both As-C and As-F bond lengths are shortened with increasing numbers of F atoms, but the angles CAsF and FAsF are almost invariant.

SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa