Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 22
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
2.
Medicine (Baltimore) ; 100(48): e27961, 2021 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-35049199

RESUMO

BACKGROUND: Endometrial cancer (EC) is the second most common malignancy of the female reproductive system worldwide, and the standard treatment for early-stage EC potentially leads to permanent infertility. The objective of this study was to investigate the efficacies of different methods on fertility preservation in patients with early-stage EC. METHODS: We searched the major online databases (PubMed, Embase, The Cochrane Library, and Web of Science) to collect the research literature on fertility preservation therapy in patients with early-stage well-differentiated EC aged ≤ 40 years from January 1999 to October 2019. The inclusion was performed using the R software (version R3.5.3) meta-analysis of a single rate. The efficacy of the following three fertility preservation treatments was evaluated from four aspects, the complete remission rate (CRR), recurrence rate (ReR), pregnancy rate (PregR), and live birth rate (LBR): a) taking oral progestin only therapy, b) hysteroscopic resection combined with progestin/levonorgestrel-releasing intrauterine system (LNG-IUS)/GnRH-a, c) LNG-IUS or combined with progestin/GnRH-a. RESULTS: A total of 23 articles were included in this study, including 446 patients with early-stage EC. In the group that took oral progestin only (n = 279), CRR, ReR, PregR, and LBR were 82% (95% confidence interval [CI], 74%-92%, P = .01), 38% (95% CI, 31%-45%, P = .35), 70% (95% CI, 62%-79%, P = .68), and 63% (95% CI, 55%-73%, P = .55), respectively. Hysteroscopic resection combined with progestin/LNG-IUS/GnRH-a therapy group (n = 96) achieved a CRR, ReR, PregR, and LBR of 95% (95% CI, 90%-100%, P = .42), 16% (95% CI, 6%-39%, P = .03), 84% (95% CI, 73%-96%, P = .39), and 72% (95% CI, 59%-87%, P = .28), respectively. LNG-IUS or combined with progestin/GnRH-a therapy group (n = 91) achieved a CRR, ReR, PregR, and LBR of 69% (95% CI, 54%-89%, P < .01), 30% (95% CI, 19%-49%, P = .36), 48% (95% CI, 18%-100%, P < .01), and 36% (95% CI, 10%-100%, P < .01), respectively. CONCLUSION: It is safe and effective for young patients with early-stage EC to receive oral progestin, hysteroscopic resection combined with progestin/LNG-IUS/GnRH-a, LNG-IUS, or progestin/GnRH-a. INPLASY REGISTRATION NUMBER: DOI 10.37766/inplasy2020.12.0137.


Assuntos
Neoplasias do Endométrio/tratamento farmacológico , Preservação da Fertilidade , Dispositivos Intrauterinos Medicados , Levanogestrel/uso terapêutico , Contraceptivos Hormonais/uso terapêutico , Feminino , Hormônio Liberador de Gonadotropina , Humanos , Metanálise como Assunto , Gravidez , Progestinas , Revisões Sistemáticas como Assunto
3.
Eur J Obstet Gynecol Reprod Biol ; 228: 38-42, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29908376

RESUMO

OBJECTIVE: This study was to determinate the expression of Tspan5 in tubal ectopic implantation sites and to explore the correlation of the expressive level of Tspan5 at maternal-fetal interface and the occurrence of tubal ectopic pregnancy. STUDY DESIGN: This is a retrospective study. Trophoblastic and endometrial tissues were collected from tubal ectopic pregnancy(Total of 40), and intrauterine pregnancy(Total of 41), who had voluntary abortion, non-pregnancy women(Total of 12), who recieved an diagnostic uterine curettage before IVF-ET for male infertility. All samples were collected from women aged 23-40 years, from February 2012 to January 2014. Results 1. In human villi Tspan5 was primarily located in cytoplasm and on the surfaces of cytotroblasts(CTs) and extravillous trophoblast(EVCTs). The intensity of Tspan5 in tubal pregnancy was significantly higher than that in normal intrauterine pregnancy, showing significant differences (Mean of IOD:109.39 ±â€¯61.84 Vs. 89.04 ±â€¯36.44;t = 2.33, P = 0.023). 2. In human deciduas of intrauterine pregnancy or endometrium of tubal pregnancy and non-pregnancy Tspan5 expressed in cytoplasm and membrane of glandular epithelial cells. The expressive level of this protein was increased in tubal pregnancy than that in intrauterine pregnancy and non-pregnancy(Mean of IOD:144.18 ±â€¯106.22 Vs. 93.43 ±â€¯67.10, P = 0.037; 144.18 ±â€¯106.22 Vs. 88.56 ±â€¯33.24, P = 0.018). CONCLUSION: Our study indicated that the trophoblasts in tubal pregnancy showed more proliferative and invasive characteristics. Dysregulation of Tspan5 in decidual microenvironment may relate to the retention of embryo in fallopian tube. SUPPORT: This study was Supported by Science and Technology Planning Project of Guangdong Province.


Assuntos
Vilosidades Coriônicas/metabolismo , Gravidez Tubária/metabolismo , Tetraspaninas/metabolismo , Trofoblastos/fisiologia , Adulto , Proliferação de Células , Endométrio/metabolismo , Feminino , Humanos , Gravidez , Estudos Retrospectivos , Adulto Jovem
4.
J Phys Chem B ; 110(10): 4914-23, 2006 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-16526731

RESUMO

Molecular recognition of mixed nucleolipids of 1-(2-octadecyloxycarbonylethyl)cytosine and 7-(2-octadecyloxycarbonylethyl)guanine in the monolayers at the air-water interface and Langmuir-Blodgett (LB) films has been investigated in detail using surface pressure/potential-area isotherms, infrared reflection-absorption spectroscopy (IRRAS), and Fourier transform infrared (FTIR) transmission spectroscopy, respectively. Prior to molecular recognition, the cytosine moieties in the monolayer were hydrogen bonded with an almost flat-on orientation, the alkyl chains were uniaxially oriented with respect to the film normal, the guanine moieties in the monolayer were stacked probably through pi-pi interaction with an end-on orientation, and the C-C-C planes of the alkyl chains were preferentially oriented parallel to the water surface. In the monolayer of equimolar mixture, molecular recognition between the cytosine and guanine moieties occurred together with the ring planes of base pairing and the C-C-C planes of the alkyl chains favorably oriented parallel to the water surface. The guanine moieties underwent an orientation change from an end-on mode before molecular recognition to a flat-on one after molecular recognition. The base pairing between the cytosine and guanine moieties in the monolayers was achieved since the N7-substituted guanine derivatives suppressed the formation of guanine tetramers. Both the IRRAS spectra of the monolayers and the FTIR spectra of the LB films presented the exact sites in the cytosine and guanine moieties for the formation of triple hydrogen bonds. The base pairing resulted in a change in molecular orientation and interaction, and the corresponding LB film exhibited a different phase transition behavior from a typical crystal transition for the cytosine-functionalized nucleolipids and an analogous glass transition for the guanine-functionalized nucleolipids. The thermal stability of the mixed LB film was improved in comparison to the LB films of pure components.


Assuntos
Citosina/análogos & derivados , Citosina/química , Guanina/análogos & derivados , Guanina/química , Lipídeos/química , Membranas Artificiais , Ar , Estrutura Molecular , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Água/química
5.
J Phys Chem B ; 109(15): 7428-34, 2005 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-16851851

RESUMO

Monolayers of N-octadecanoyl-L-alanine at the air-water interface on pure water and metal ion containing subphases have been studied using polarized infrared reflection-absorption spectroscopy (IRRAS). The metal complex and hydrogen bond formation with the headgroups give rise to a change in chain order depending on metal ion in the subphase. On pure water and Ag(+)-/Pb(2+)-containing subphase, the antisymmetric CH(2) stretching band intensity [nu(a)(CH(2))] undergoes a slower increase than the symmetric one [nu(s)(CH(2))] below the Brewster angle, so the intensity ratios of nu(a)(CH(2))/nu(s)(CH(2)) are less than 1 in the cases of Ag(+) and Pb(2+). Beyond the Brewster angle, the nu(a)(CH(2)) band intensities are substantially reduced in comparison with the nu(s)(CH(2)) ones in the cases of pure water and Ag(+), but the nu(a)(CH(2)) bands still remain negative-oriented in the presence of Pb(2+). These unusual spectral features indicate that the alkyl chains take a preferential orientation with their C-C-C planes parallel to the water surface. The parallel packing of the alkyl chains results from the intermolecular hydrogen bonds C=O...H-N between the neighboring amide groups, strengthened by the metal complex of covalent interaction. On the Ca(2+)-/Cu(2+)-containing subphase, the corresponding polarized spectra display a usual behavior. The alkyl chains are roughly estimated to be inclined around 35-40 degrees from the surface normal on the assumption of chain segment orientation for the monolayers in the liquid-expanded phase. The chain conformation and tilt are closely related to the formation of intramolecular hydrogen bonds and the ionic interaction of the metal complex in the cases of Ca(2+) and Cu(2+).


Assuntos
Aminoácidos/química , Ligação de Hidrogênio , Metais/química , Espectrofotometria Infravermelho/métodos , Água/química , Absorção , Ar , Cálcio/química , Carbono/química , Fenômenos Químicos , Físico-Química , Cobre/química , Concentração de Íons de Hidrogênio , Íons , Modelos Químicos , Espectrofotometria/métodos
6.
Spectrochim Acta A Mol Biomol Spectrosc ; 60(13): 2985-92, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15477134

RESUMO

The binding of chlorobenzylidine to calf thymus DNA has been studied in detail by means of circular dichroism (CD), nuclear magnetic resonance (1H NMR), viscosimetry and denaturation temperature (Tm). Chlorobenzylidine is found to intercalate between base pairs of DNA as evidence by: (1) induced circular dichroism; (2) broadened 1H NMR signals; (3) enhanced viscosity; and (4) increased denaturation temperature of the DNA helix. In addition, Scatchard plot from CD titration data gives a binding constant of 2.6 x 10(4) M(-1) and a binding site size of 4 base pairs at 25 degrees C. Matrix rank analysis shows that there are three main components contributing to the observed CD spectra. The nuclear magnetic resonance experiment shows that the planar aromatic ring of tetrahydroberberine group in chlorobenzylidine intercalates between the base pairs of DNA when chlorobenzylidine is bound to DNA.


Assuntos
DNA/química , DNA/metabolismo , Compostos Policíclicos/química , Compostos Policíclicos/metabolismo , Animais , Compostos de Benzilideno , Bovinos , Dicroísmo Circular , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Desnaturação de Ácido Nucleico , Temperatura , Termodinâmica , Titulometria , Viscosidade
7.
J Chem Phys ; 120(1): 379-83, 2004 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-15267299

RESUMO

Langmuir-Blodgett (LB) films of N-octadecanoyl-L-alanine and its silver and zinc complexes have been investigated by variable-temperature Fourier transform infrared transmission spectroscopy. The thermal stability of LB films is improved through an intermolecular hydrogen bond and metal complex. The intermolecular hydrogen-bonding interaction between hydrophilic head groups in the same monolayers and the metal complex between one head group and another in the neighboring monolayers considerably increase the interaction between the corresponding hydrophobic alkyl chains. It is shown that the transformation of the triclinic subcell packing of the molecules in the LB films prior to and after the silver complex into hexagonal packing occurs before the phase transition accompanied with a change in molecular orientation. The phase transition behavior of the LB films is varied from a small temperature interval to large one depending on the hydrogen bond and metal complex.

8.
Chem Commun (Camb) ; (14): 1664-5, 2004 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-15263969

RESUMO

Different sizes of nanotubes of poly(2-methoxy-5-(n-hexadecyloxy)-p-phenylene vinylene)(MH-PPV) have been fabricated at the air/water interface by compressing a monolayer of MH-PPV beyond its collapse point, and their structural characteristics were studied by means of TEM, AFM, SAXRD, IRRAS.

9.
J Pharm Sci ; 93(4): 1039-46, 2004 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-14999739

RESUMO

SU-118 is a newly synthesized antidiabetic agent and shows the best hypoglycemic effect among a series of analogs. Its binding properties and binding sites located on human serum albumin (HSA) have been studied using UV absorption and fluorescence spectroscopy. The results of spectroscopic study and the thermodynamic parameters obtained suggest that SU-118 binds to the hydrophobic cavity of human serum albumin and the hydrophobic interaction is the predominant intermolecular force stabilizing the complex. Fluorescent probe displacement studies show that SU-118 can displace competitively both dansylamide and dansylsarcosine from HSA. It is suggested that SU-118 can bind to both site I and site II, but the primary interaction may take place at site I. A binding constant of 1.4 x 10(4) M(-1) and a binding site of 2.0 are obtained from absorbance titration data. The value of binding constant is of the same order of magnitude as that from fluorescence titration. This study provides a molecular basis for elucidating the mechanism of drug acting and predicting unfavorable drug interaction.


Assuntos
Cumarínicos/química , Hipoglicemiantes/química , Sarcosina/análogos & derivados , Albumina Sérica/química , Compostos de Sulfonilureia/química , Sítios de Ligação , Compostos de Dansil/química , Desulfurococcaceae , Corantes Fluorescentes , Humanos , Microscopia de Fluorescência , Ligação Proteica , Sarcosina/química , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Termodinâmica , Triptofano/análise
10.
Spectrochim Acta A Mol Biomol Spectrosc ; 60(1-2): 401-4, 2004 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-14670505

RESUMO

FTIR spectroscopy is used to compare the difference in molecular structure between Langmuir-Blodgett (LB) films (transferred at the surface pressure 40 mN/m with the vertical method and 0 mN/m with the horizontal method) and bulk sample of N-Octadecanoyl-L-alanine amphiphiles. The bulk sample possesses a very similar microstructure (intermolecular hydrogen-bonding interaction and triclinic chain packing) to the well-ordered LB films. Much information on molecular structure of the bulk sample is obtained using FT-Raman spectroscopy, and several weak Raman scattering peaks are assigned.


Assuntos
Alanina/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Análise Espectral Raman/métodos , Estearatos/química , Lasers , Filmes Cinematográficos , Conformação Proteica , Espalhamento de Radiação
11.
Spectrochim Acta A Mol Biomol Spectrosc ; 60(1-2): 413-6, 2004 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-14670507

RESUMO

Order-disorder transitions of 9-monolayer Langmuir-Blodgett (LB) films of 7-(2-octadecyloxycarbonylethyl)guanine (ODCG) before and after recognition to cytidine were investigated by Fourier transform infrared (FTIR) spectroscopy. The different order-disorder transitions suggest that molecular recognition between ODCG and cytidine influence these two LB films on the order-disorder process of alkyl tailchain. Cleavage of the multi-hydrogen bonds was also observed by the infrared spectroscopy at elevated temperature.


Assuntos
Citidina/química , Guanina/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Guanina/análogos & derivados , Ligação de Hidrogênio , Modelos Químicos , Filmes Cinematográficos , Temperatura
12.
J Colloid Interface Sci ; 270(2): 309-14, 2004 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-14697695

RESUMO

Surface-enhanced Raman scattering (SERS) spectra of four amphiphilic nucleolipids in single-layer Langmuir-Blodgett (LB) films deposited on silver island film substrates from pure water and complementary nucleotide-containing subphase and corresponding powder normal Raman spectra were obtained. The analysis of these spectra indicates that the SERS effect is mainly caused by a charge-transfer mechanism, and only the nucleobase headgroup moieties and complementary bases combined with them through hydrogen bonds, which are directly in contact with the silver island film substrates, could be enhanced. For the amphiphilic nucleolipids with the identical nucleobase headgroups, the SERS spectra of the LB films are similar, implying that the orientations of these nucleobase moieties on the silver substrates are analogous. However, the nucleobase takes different orientations on the silver substrates before and after complementary binding. The nucleobases in the LB films deposited from pure water are nearly lying flat on the silver surface, while the complementary binding pairs transferred from the air/water interface tend to take an end-on orientation on the metal surface.


Assuntos
Coloides/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Materiais Biocompatíveis , Ligação de Hidrogênio , Lipídeos/química , Modelos Químicos , Estrutura Molecular , Espalhamento de Radiação , Prata/química , Compostos de Prata/química , Análise Espectral Raman , Propriedades de Superfície
13.
Spectrochim Acta A Mol Biomol Spectrosc ; 59(7): 1631-41, 2003 May.
Artigo em Inglês | MEDLINE | ID: mdl-12714086

RESUMO

A PPV derivative, poly(2-methoxy,5-(8-methoxy-3,6-dioxa-1-undecoxy)-p-phenylene vinylene), has been synthesized by the Gilch route to study the influence of a long alkyl side chain and a di(ethylene oxide) methyl ether group on the multilayer structure obtained by Langmuir-Blodgett (LB) technique. UV-visible, PL, and FTIR spectra are applied to study the conformation and orientation of the MMDU-PPV molecules in multilayer organization. MMDU-PPV is apt to form a transferable monolayer film, in which the plane of its pi system is perpendicular to the air-water interface. The adjacent conjugated main chains of MMDU-PPV in LB films are aligned in parallel fashion and packed with the plane of its pi system approximately perpendicular to the layer plane and not organized to compact pi-stacking structure for introducing di(ethylene oxide) methyl ether (DEOM) side chains to conjugated main chains. The long alkyl side chains are characterized by all trans-zigzag conformation and average tilt angle of 36+/-1.5 degrees. The layer-by-layer multilayer of MMDU-PPV obtained by Langmuir-Blodgett technique exhibits some in-plane anisotropy and more pure photoluminescence than that of the dilute MMDU-PPV solution.


Assuntos
Polivinil/química , Polivinil/síntese química , Ar , Anisotropia , Luminescência , Conformação Molecular , Estrutura Molecular , Fotoquímica , Espectrofotometria , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Água
14.
Spectrochim Acta A Mol Biomol Spectrosc ; 59(2): 219-27, 2003 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-12685894

RESUMO

5,15-di(4-hydroxyphenyl)-10,20-di(hexadecyloxyphenyl) porphyrin P was solubilized in nonionic polyoxyethylene(9.5) octylphenol (Triton X-100 or TX-100) micelle solutions. By means of analyzing the UV-visible and fluorescence spectra of the synthesized amphiphilic porphyrin P in different solvent environments, and the relationship between the solubilizing location of the porphyrins in TX-100 micelle and the microenvironment polarity, P is shown to involve in a transfer process for the porphyrin moiety from inner to the outer surface of TX-100 micelle as the pH is increased. The kinetic study of porphyrin incorporate with Cu(II) shows that metalation rate of porphyrin increases with the pH increasing, indicating that metalation rate could be controlled by changing pH.


Assuntos
Micelas , Porfirinas/análise , Porfirinas/química , Espectrometria de Fluorescência/métodos , Espectrofotometria/métodos , Raios Ultravioleta , Detergentes/farmacologia , Concentração de Íons de Hidrogênio , Cinética , Modelos Químicos , Octoxinol/farmacologia
15.
J Colloid Interface Sci ; 258(2): 432-4, 2003 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-12618116

RESUMO

The coordination polymer, P(ZnL) (L=N,N'-bis[2-hydroxy-4-(dodecyloxy)benzaldehyde)]-ethylenedimine), forms a novel uniform lamellar superstructure in organic liquids, which exhibits intense fluorescence in organic dispersions as well as in the corresponding cast films.

16.
Artigo em Inglês | MEDLINE | ID: mdl-12659897

RESUMO

The interaction of chlorobenzylidine with herring sperm DNA has been investigated by fluorescence, absorption, DNA melting experiment and differential scanning calorimetry (DSC). When bound to DNA, chlorobenzylidine shows hypochromism and red shift in absorption spectra, fluorescence quenching and polarization increasing in fluorescence spectra and increasing in DNA melting temperature. These spectral characteristics strongly support intercalation of chlorobenzylidine into herring sperm DNA. Scatchard plots constructed from fluorescence titration data give a binding constant of 3.2 x 10(4) M(-1) and a binding site size of six base pairs per bound drug molecule. The intercalative interaction is exothermic with a van't Hoff enthalpy of -30.6 kJ mol(-1). This result is obtained from DSC experiment. In addition, DeltaG degrees =-28.5 kJ mol(-1), and DeltaS degrees =-7.1 J mol(-1) K(-1). These results show that the binding of chlorobenzylidine to herring sperm DNA is exothermic.


Assuntos
Compostos Policíclicos/química , Animais , Compostos de Benzilideno , Varredura Diferencial de Calorimetria , DNA/metabolismo , Relação Dose-Resposta a Droga , Peixes , Íons , Cinética , Masculino , Espectrometria de Fluorescência , Espectrofotometria , Espermatozoides/metabolismo , Temperatura , Termodinâmica
17.
Spectrochim Acta A Mol Biomol Spectrosc ; 59(5): 1045-50, 2003 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-12633721

RESUMO

Monolayer behavior of a nucleolipid amphiphile, 7-(2-octadecyloxycarbonylethyl)guanine (ODCG), on aqueous cytidine solution was investigated by means of surface-molecular area (pi-A) isotherms. It indicates that molecular recognition by hydrogen bonding is present between ODCG monolayer and the cytidine in subphase. The Fourier transform infrared (FTIR) transmission spectroscopic result indicates that the cytidine molecules in the subphase can be transferred onto solid substrates by Langmuir-Blodgett (LB) technique as a result of the formation of Watson-Crick base-pairing at the air/water interface. Investigation by rotating polarized FTIR transmission also suggests that the headgroup recognition of this amphiphile to the dissolved cytidine influence the orientation of the tailchains.


Assuntos
Citidina/química , Guanina/análogos & derivados , Guanina/química , Espectroscopia de Infravermelho com Transformada de Fourier
18.
Chem Commun (Camb) ; (5): 492-3, 2002 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-12120556

RESUMO

In dilute aqueous solution, micelle-forming sodium hexadecylimino diacetate assembles into vesicles induced by Cu(II), Co(II) and Ni(II) ions.


Assuntos
Ácidos Dicarboxílicos/química , Lipossomos/química , Metais/farmacologia , Tensoativos/química , Alcanos/química , Iminas/química , Micelas
19.
J Colloid Interface Sci ; 246(2): 335-42, 2002 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-16290420

RESUMO

In the four studied monoalkyl phosphoric acids (n-C(12)H(25)OPO(OH)(2), MDP; n-C(14)H(29)OPO(OH)(2), MTP; n-C(16)H(33)OPO(OH)(2), MHP; and n-C(18)H(37)OPO(OH)(2)MOP), only MOP can form an insoluble monolayer at the air/water interface (pH 5.6), suggesting that the longer alkyl chain (> or =C(18)) is essential for the formation of insoluble monolayers. On the contrary, all four corresponding dialkyl phosphoric acids ((n-C(12)H(25)O)(2)PO(OH), DDP; (n-C(14)H(29)O)(2)PO(OH), DTP; (n-C(16)H(33)O)(2)PO(OH), DHP; and (n-C(18)H(37)O)(2)PO(OH) DOP) can form insoluble monolayers, with only the pi-A isotherm of DDP showing a phase transition plateau at 25 degrees C. The enhancement of the subphase temperature not only increases the plateau pressure of the DDP monolayer, but also induces the emergence of a plateau for the DTP monolayer. In contrast to the weak influence of Na(+) and K(+) (1 x 10(-4) M in the subphases, pH approximately 5.6) on the pi-A isotherm of DDP, Ca(2+), Sr(2+), and Ba(2+) (1 x 10(-4) M in the subphases, pH approximately 5.6) have an evident impact on the isotherms of DDP, and the different isotherm results indicate that DDP can recognize the three divalent cations at the air/water interface. In addition, the gaseous portion and phase transition plateaus of the isotherms of some DAPs on pure water and on subphases containing Ca(2+), Sr(2+), or Ba(2+) were well simulated by Volmer's equation of state and Vollhardt's equation, except for a small difference for gas phases around critical points. The relationship between the plateau and the net molecule area is also discussed.

20.
J Colloid Interface Sci ; 251(1): 125-30, 2002 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-16290710

RESUMO

A poly(heteroarylene methine) derivative, poly[(2,5-thiophenediyl) (p-n-methyl, n-octylaminobenzylidene) (2,5-thiophenequinodimethaneiyl)] (PTABQ), has been synthesized and spread at the air-water interface. The influences of three kinds of solutions on PTABQ monolayer behavior at the air-water interface have been investigated via the measurements of the pi-A isotherm and film stability. The results show that all three kinds of PTABQ solutions are apt to form the stable and transferable monolayer film organized with the plane of its pi-system nearly perpendicular to the air-water interface. Moreover, the monolayer-forming ability of PTABQ can be improved by introducing a water-soluble amphiphilie as an extractable spread-aiding component, which is further proved by the AFM images and FTIR spectra of the transferred films. UV-visible absorption spectra indicate that the well-ordered layer-by-layer structure is successfully controlled in the LB films. The optical bandgap of PTABQ is reduced for the ordered arrangement of its molecules in LB films. The intrinsic electrical conductivity of PTABQ LB films is 8.1 x 10(-8) S/cm and the conductivity of iodine-doped films is 5.7 x 10(-7) S/cm.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...