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

Bases de dados
País/Região como assunto
Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
Perception ; 53(3): 163-179, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38158215

RESUMO

The accurate perception of groups with outliers can help us identify potential risks. However, it is unclear how outliers affect the perception of group emotion. To address this question, we conducted a study on group emotion perception in the context of facial identity. We presented 74 participants with pictures of crowds, and asked them to evaluate the valence ratios and intensity of the crowd by means of the Emotional Aperture Measure. The results revealed that outlier emotions were often overestimated within crowds. Moreover, we found that the emotional expression of a close friend modulated the perception of outliers. Specifically, when a close friend expressed the group emotion, participants overestimated the outlier less than when a close friend expressed the outlier emotion. These results suggest that people can detect outliers within groups, and that their perception of group emotion is influenced by close friends. Thus, we provide evidence that facial identity affects group emotion perception.


Assuntos
Emoções , Expressão Facial , Humanos
2.
Curr Psychol ; : 1-14, 2023 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-37359704

RESUMO

Highly aggressive individuals tend to interpret others' motives and intentions as hostile in both offline and online social situations. The current study examined whether hostile interpretation bias can be modified to influence cyber-aggression in Chinese middle school students using an interpretation bias modification program. Gender differences and the heterogeneity of cyber-aggression were also investigated since previous studies suggest that they play important roles in determining the intervention effect. One hundred and twenty-one middle school students were randomized to receive either an eight-session interpretation bias modification task (CBM-I; n = 61) or an eight-session placebo control task (PCT; n = 60) over four weeks. Measures of hostile attribution bias and cyber-aggression were administered at baseline, post-training, and at one week follow-up. Results showed that compared to PCT, participants in CBM-I showed a significant reduction in reactive cyber-aggression. However, contrary to our expectation, there was no significant difference between the two groups in the reduction of hostile attribution bias after training. The moderated mediation analysis revealed that the effect of CBM-I on hostile attribution bias and the mediating role of hostile attribution bias in the relationship between CBM-I condition and reactive cyber-aggression was only observed among females, but not among males. These findings provide initial evidence for the potential of CBM-I in reducing hostile attribution bias and cyber-aggression. However, for male students, CBM-I might not be effective enough as expected. Supplementary Information: The online version contains supplementary material available at 10.1007/s12144-023-04433-3.

3.
Aggress Behav ; 48(2): 152-162, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34888891

RESUMO

Although previous studies have focused on the associations between peer group relations and cyber-aggression, limited attention has been paid to the heterogeneity in the functions of cyber-aggression. This study explored the unique associations of peer relations with proactive and reactive cyber-aggression and the possible mechanisms underlying them in a sample of adolescents using a longitudinal study design. A total of 829 middle school students completed the Cyber-rage and Cyber-reward Aggression Subscales of the Cyber-Aggression Typology Questionnaire, the Peer Relations Scale, the Social Information Processing-Attributional Bias Questionnaire, and the Self-efficacy for Aggression Scale twice at a 6-month interval. Multiple mediation analyses and bootstrapping were conducted using the Mplus 8 software. The results indicated that satisfying peer relations were negatively correlated with reactive cyber-aggression and positively associated with proactive cyber-aggression. Moreover, hostile intent attribution and self-efficacy for aggression mediated the associations between peer relations and both functions of cyber-aggression, however, in different ways. Unsatisfying peer relations were associated with higher levels of hostile intent attribution and lower levels of self-efficacy for aggression and predicted increases in reactive cyber-aggression. In contrast, satisfying peer relations were associated with lower levels of hostile intent attribution and higher levels of self-efficacy for aggression and predicted increases in proactive cyber-aggression. The findings indicated that different functions of cyber-aggression might be related to different mediation mechanisms, which sheds light on the prevention of cyber-aggression in the future.


Assuntos
Agressão , Relações Interpessoais , Adolescente , China , Hostilidade , Humanos , Estudos Longitudinais , Grupo Associado
4.
J Ment Health ; 30(4): 541-548, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32915668

RESUMO

BACKGROUND: Cognitive strategies are preferred among nurses who have limited opportunities in the workplace to use behavioral strategies to cope with negative life events. AIMS: To explore whether different cognitive emotion regulation profiles could be distinguished in nurses exposed to workplace violence, and to investigate whether such profiles had differential associations with depressive symptoms. METHOD: An online survey was conducted among nurses exposed to workplace violence (N = 399). Latent profile analysis was performed to identify discrete profiles based on the use of cognitive emotion regulation strategies. The Bolck, Croon, and Hagenaars method was applied to compare the latent profiles on the depressive symptoms. RESULTS: Seven latent profiles were identified: Low Regulators, Medium Regulators, High Regulators, Intensely Adaptive Regulators, Moderately Adaptive Regulators, Intensely Maladaptive Regulators, and Moderately Maladaptive Regulators. High Regulators had the highest level of depressive symptoms. Although using less adaptive strategies, Low Regulators did not report significantly more depressive symptoms than Medium Regulators, Intensely Maladaptive and Moderately Maladaptive Regulators. CONCLUSIONS: The adaptability of cognitive emotion regulation strategies depends on the conjunction of different strategies one person has at his disposal. Cognitive emotion regulation skill training should focus on flexible implementation of strategies and decreasing use of maladaptive strategies.


Assuntos
Regulação Emocional , Enfermeiras e Enfermeiros , Violência no Trabalho , Cognição , Depressão , Emoções , Humanos
5.
World J Microbiol Biotechnol ; 29(3): 499-504, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23292647

RESUMO

Helicobacter hepaticus and Helicobacter pylori both belong to Helicobacter species. Strains of Lactobacillus acidophilus, including L4 and L6, have shown significant inhibitory effects on H. pylori. Based on this phenomenon, we aim to investigate the inhibitory effect of L. acidophilus on H. hepaticus. Both standard and isolated H. hepaticus strains were grown under microaerophilic conditions at 37 °C in the presence of L. acidophilus supernatant, or lactic acid. The diameters of the inhibition zones were measured on the solid culture media. In liquid culture, the cell concentrations were measured and the urease activity was determined by phenol red staining. Sixteen strains of L. acidophilus isolated from human feces (named as L1-L16) showed anti-H. hepaticus effects. Two of them (L4 and L6) exhibited the most apparent effects on H. hepaticus inhibition. The L. acidophilus supernatant of L4 and L6 significantly increased the diameters of the inhibition zones compared with that of the lactic acid control (P < 0.05). The inhibitory role of L. acidophilus supernatant was independent of the pH value of solution (P > 0.05). Moreover, in liquid culture, L. acidophilus supernatant significantly reduced the cell growth rate and the urease activity of H. hepaticus cells in a time-dependent pattern (P < 0.05 compared with lactic acid control). No obvious difference was observed between the standard and isolated strain of H. hepaticus (P > 0.05). Our results indicate that L. acidophilus can decrease the viability and urease activity of H. hepaticus in vitro and this inhibition is independent of pH levels. This provides evidence for developing novel approaches for the prevention and treatment of H. hepaticus infection.


Assuntos
Antibiose , Helicobacter hepaticus/crescimento & desenvolvimento , Lactobacillus acidophilus/crescimento & desenvolvimento , Animais , Meios de Cultura , Infecções por Helicobacter/microbiologia , Infecções por Helicobacter/terapia , Helicobacter hepaticus/enzimologia , Humanos , Camundongos , Viabilidade Microbiana , Urease/metabolismo
6.
Technol Health Care ; 31(5): 1911-1922, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37270823

RESUMO

BACKGROUND: Studies have shown that community-based group rehabilitation activities can have a positive impact on patients. OBJECTIVE: This study attempted to improve schizophrenia patients' social and self-cognition through short-term group-based cognitive behavioral therapy (G-CBT), break negative coping styles, and improve the patients' quality of life. METHODS: The patients with schizophrenia who participated in long-term community-based group rehabilitation were treated with G-CBT. Training on coping styles was conducted to improve their self-cognition and social cognition, and the rehabilitation effects of G-CBT on these patients were evaluated. RESULTS: Compared with the control group, patient scores for self-esteem, self-efficacy, and positive coping in the G-CBT group increased, while patient scores for negative coping decreased. Compared with the control group, the differences in the total scores for mental health and the five dimensions of physical functioning, general health, vitality, social functioning, and emotional role function in the short-form (SF-12) survey were statistically significant. Compared with the baseline data, the differences in self-esteem, self-efficacy, positive coping, negative coping, and quality of life scores were statistically significant. CONCLUSION: Short-term G-CBT had a good effect on patients with chronic schizophrenia who participated in community-based group rehabilitation for the long-term.


Assuntos
Terapia Cognitivo-Comportamental , Esquizofrenia , Humanos , Esquizofrenia/terapia , Saúde Mental , Qualidade de Vida , Terapia Cognitivo-Comportamental/métodos , Cognição
7.
BMC Psychol ; 10(1): 213, 2022 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-36068639

RESUMO

AIMS: Although community psychiatric rehabilitation plays an important role in returning persons with schizophrenia to the society, many patients in China stay in rehabilitation centers for longer periods of time and subsequently fail to integrate. This study is aimed to explore the underlying causes of this trend and identify possible solutions. METHODS: This study used a qualitative descriptive design to examine the persons with schizophrenia who stay in rehabilitation centers for longer periods of time. The researchers conducted semi-structured telephone interviews with the patients recruited through purposeful sampling. The audio-recorded interviews were transcribed in transcripts in Chinese. Thematic analysis was performed using Colaizzi's 7-step method. RESULTS: Most patients believe that they have gained knowledge, improved skills, friendship and social circles through community mental rehabilitation, with the sense of belonging and enriched life strongly attracting them to the rehabilitation centers. They felt that the difficulty of further integration into society is mainly because of social prejudice and rejection. In addition, the activities of community mental rehabilitation meet the needs of social communication, which also hinder patients from further entering the society. CONCLUSIONS: Persons with schizophrenia with long-term stay in community mental rehabilitation centers meet their friendship, sense of belonging and social needs by participating in rehabilitation activities. Providing special social opportunity for these patients can get them out of the rehabilitation center. Overall, it is possible for patients to gradually return to society in a collective form.


Assuntos
Reabilitação Psiquiátrica , Esquizofrenia , China , Comunicação , Humanos , Pesquisa Qualitativa , Inquéritos e Questionários
8.
Zhonghua Gan Zang Bing Za Zhi ; 19(9): 670-3, 2011 Sep.
Artigo em Zh | MEDLINE | ID: mdl-22152381

RESUMO

OBJECTIVE: To evaluate antiviral effects of Peg-IFNa-2a in patients with chronic hepatitis B. METHODS: 92 chronic hepatitis B patients were enrolled to receive the treatment with Peg-IFNa-2a 180 µg subcutaneous injection once weekly. The patients who did not get early response were divided into 3 groups: group 1, extend the treatment to 72 weeks; group 2, combined with nucleus(s)ide analogue (entecavir or adefovir) treatment; group 3, continue the treatment until 48 weeks. HBV DNA and quantitative HBsAg were assessed at baseline, week 12, 24, 36 and after 24 weeks follow-up. RESULTS: Patients in group 1 had significantly higher SVR rate (78.3%) than patients in group 3 (38.1%, X2=7.33, P<0.05). The mean reduction of HBsAg in group 1 at 24 weeks of post-treatment follow up was higher than that in group 3 (t=2.11, P<0.05). In group 2 the mean reductions of HBV DNA at 24 weeks of post-treatment follow up were (3.9+/-1.1) log10 copy/ml and (3.7+/-1.3) log10 copy/ml respectively with combination of entecavir or adefovir, both of which were significantly higher than that in group 3(t=8.45 and 6.31, P<0.05); the SVR rates in the entecavir group and the adefovir group (83.3% and 85.7%, respectively) were significantly higher than that in group 3 (X2=8.20 and 7.78, P<0.05); the mean reductions of HBsAg in the entecavir group and the adefovir group [(0.8+/-0.5) log10 IU/ml and (0.9+/-0.3) log10 IU/ml, respectively ] were significantly greater than group 3[(0.4+/-0.3) log10 IU/ml, t=3.05 and 4.58, P<0.05]. The level of HBV DNA and C genotype were the main predictors of response. CONCLUSION: Individualizing therapy by prolonging the duration of Peg-IFNa-2a treatment to 72 weeks or adding nucleoside analogues such as entecavir and adefovir in patients without early response may substantially increase the SVR rate and lead to the decrease of HBsAg.


Assuntos
Antivirais/uso terapêutico , Hepatite B Crônica/tratamento farmacológico , Interferon-alfa/uso terapêutico , Adenina/análogos & derivados , Adenina/uso terapêutico , Adulto , Feminino , Guanina/análogos & derivados , Guanina/uso terapêutico , Humanos , Masculino , Pessoa de Meia-Idade , Organofosfonatos/uso terapêutico , Resultado do Tratamento
9.
Tob Induc Dis ; 18: 72, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32934618

RESUMO

INTRODUCTION: Psychological, physiological and social factors play an important role in the initiation, persistence, dependence and relapse of smoking behaviors, and coping style and smoking abstinence self-efficacy can all affect nicotine dependence. METHODS: A cross-sectional sample of 568 quitters from 19 communities in Beijing in 2019 was surveyed. Demographic information and psychological characteristics of smokers were collected by an interview questionnaire, and psychological traits scales including the Smoking Abstinence Self-Efficacy (SASE) and the Trait Coping Style Questionnaire (TCSQ). We compared differences in psychological traits across demographic information and explored the relationship between nicotine dependence and coping styles and self-efficacy in refusing to smoke. RESULTS: Significant differences were identified in self-efficacy in refusing to smoke and across dimensions among quitters by gender, job type, education level, and monthly income level (all p<0.05). Males had lower self-efficacy in the habitual/addictive context than females; retirees had better overall self-efficacy and self-efficacy in the negative/emotional context than business service workers and professionals; and high-educated, high-income quitters had lower self-efficacy in the negative/emotional context. There are significant differences in positive coping styles among quitters of different ages, levels of education, and types of work (all p<0.05). The results further showed that the underage population, highly educated population, and practitioners other than those in retirement, are less likely to use positive coping styles. Interventional effects analysis showed that a higher sense of self-efficacy in addictive contexts can counteract some of the negative coping styles that induce smoking. CONCLUSIONS: Self-efficacy played an indirect mediating role between negative coping style and nicotine dependence; individuals who used more negative coping styles were more likely to engage in smoking and therefore were more nicotine dependent. Hence, it is necessary to reduce the use of negative coping strategies and improve the self-efficacy of smoking abstinence in the face of addiction.

10.
Zhonghua Yu Fang Yi Xue Za Zhi ; 43(11): 1000-3, 2009 Nov.
Artigo em Zh | MEDLINE | ID: mdl-20137525

RESUMO

OBJECTIVE: To investigate the social health status of the HIV infected and their families in a high HIV/AIDS prevalence village in Hunan province and to examine the relations of the social health status, responses and social support. METHODS: A total of 51 HIV infected persons (infected group), 49 family members of the infected (family member group) and 96 normal persons (control group) were surveyed by Social Health Measurement Scale-a sub-scale of Self-rated Health Measurement Scale (SRHMS), Social Support Assessment Scale (SSAS) and Trait Coping Style Questionnaire (TCSQ). RESULTS: (1) In regard to the total scores of social health, responding style and social support, significant differences were found among the infected group, the group of family members and the control group (62.9 +/- 18.6, 79.8 +/- 18.0, 86.5 +/- 21.3, F = 18.16; 28.7 +/- 4.3, 27.2 +/- 5.4, 25.9 +/- 6.4, F = 5.21; 33.8 +/- 8.1, 41.0 +/- 6.6, 38.1 +/- 6.8, F = 13.23; P < 0.01). (2) Subjective care and support, the educational status, the marital status and support utilization were significant predictors to the social health status of the infected group (R(2) = 0.73, F = 27.78, P < 0.01). (3) Subjective support and negative responding style were significant predictors to the social health status of the group of family members (R(2) = 0.32, F = 12.35, P < 0.01). CONCLUSION: The HIV infected and their families have more negative responding style, make less use of social support and hold a inferior social health status. It's necessary to exert psychological intervention targeting at these population group.


Assuntos
Família/psicologia , Infecções por HIV/psicologia , Apoio Social , Adolescente , Adulto , Idoso , Estudos de Casos e Controles , China , Feminino , Nível de Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Estudos de Amostragem , Inquéritos e Questionários , Adulto Jovem
12.
Org Lett ; 5(20): 3709-11, 2003 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-14507211

RESUMO

[structure: see text] A dyad of eosin and tris(2,2'-bipyridine)Ru(II) was prepared, and its photophysical properties were investigated. The photosensitization of eosin is greatly enhanced by introduction of tris(2,2'-bipyridine)Ru(II), which is verified via photooxygenation of anthracene derivatives. The electron-transfer mechanism of photosensitization is also discussed.


Assuntos
2,2'-Dipiridil/análogos & derivados , 2,2'-Dipiridil/química , Amarelo de Eosina-(YS)/análogos & derivados , Fármacos Fotossensibilizantes/química , 2,2'-Dipiridil/síntese química , Antracenos/química , Complexos de Coordenação , Espectroscopia de Ressonância de Spin Eletrônica , Transporte de Elétrons , Amarelo de Eosina-(YS)/síntese química , Oxirredução , Fotoquímica , Fármacos Fotossensibilizantes/síntese química , Oxigênio Singlete/química , Espectrometria de Fluorescência
13.
Photochem Photobiol ; 80: 112-4, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15339225

RESUMO

We report on the emission spectra and emission quantum yields of a newly synthesized hypocrellin dye, 2-demethoxy-2,3-ethylenediamino hypocrellin B (EDAHB), and its parent HB in different solvents of varying polarity. Our results demonstrate that EDAHB is one of the few dyes that exhibit highly solvent polarity-dependent fluorescence in the useful region (680-730 nm). Therefore, it offers some applications in the biomedical field as a fluorescent probe molecule. The solvatochromic effect of EDAHB is proposed to be due to a distinct change in the dipole moment of the dye on excitation. A photoinduced intramolecular proton transfer and a photoinduced intramolecular electron transfer process are considered relevant for the fluorescence properties of HB and EDAHB, respectively.


Assuntos
Perileno/análogos & derivados , Perileno/química , Fármacos Fotossensibilizantes/química , Quinonas/química , Quinoxalinas/química , Elétrons , Prótons , Espectrometria de Fluorescência/métodos
14.
Photochem Photobiol ; 78(4): 411-5, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-14626671

RESUMO

To improve the amphiphilicities and red absorption of the hypocrellins, three novel 2-amino-2-demethoxy-hypocrellins were synthesized by the mild reactions of hypocrellin B with 4-(2-amino-ethyl)morpholine, N,N-dimethylethylenediamine and 1-(2-amino-ethyl)piperazine, respectively. The structures of these derivatives were characterized with proton nuclear magnetic resonance, infrared and mass spectra (MS). The ultraviolet-visible absorption and fluorescence spectra of the derivatives were measured and the new amino-substituted hypocrellins showed strong absorption in the domain of the phototherapeutic window (600-900 nm). Their amphiphilicities evaluated via the partition coefficients between n-octanol and phosphate-buffered saline buffer improved remarkably. Electron paramagnetic resonance spin-trapping measurements were used to investigate the photodynamic action of the three compounds in the presence of oxygen. Singlet oxygen (1O2) and superoxide anion radical (O2.-) generated by illuminating the hypocrellin derivatives in aerobic solution were observed.


Assuntos
Perileno/análogos & derivados , Perileno/síntese química , Fotoquimioterapia , Fármacos Fotossensibilizantes/síntese química , Quinonas/síntese química , Perileno/química , Fenol , Fármacos Fotossensibilizantes/química , Quinonas/química , Espécies Reativas de Oxigênio , Espectrometria de Fluorescência
15.
J Photochem Photobiol B ; 72(1-3): 61-7, 2003 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-14644567

RESUMO

Two phenmethylamino hypocrellin B derivatives are novel photodynamic agents synthesized by a mild reaction between hypocrellin B and phenmethylamine. The red absorption of the photosensitizers is enlarged distinctly and the peri-hydroxylated perylenequinone structure of the parent HB is preserved. 9,10-diphenyl-anthracene (DPA) bleaching and electron paramagnetic resonance (EPR) spin trapping techniques were used to study the photodynamic activities of the phenmethylamino hypocrellin B derivatives in the presence of oxygen. Singlet oxygen (1O2) and superoxide anion radical (O2*-) generated in the process of illumination of the phenmethylamino hypocrellin B in aerobic solution were observed. The photodamage of PMAHBs to MGC803 cancer cells was investigated in vitro. The results in vitro reveal that the phenmethylamino hypocrellin B derivatives show a much less significant decrease in cytotoxicity than that of their parent HB. It exhibits higher selectivity of light-orientation, which can decrease the damage to normal tissues by irradiating the tumor tissues, and so increases the drug safety.


Assuntos
Perileno/análogos & derivados , Perileno/síntese química , Perileno/farmacologia , Fármacos Fotossensibilizantes/síntese química , Fármacos Fotossensibilizantes/farmacologia , Quinonas/síntese química , Quinonas/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Sobrevivência Celular/efeitos da radiação , Relação Dose-Resposta a Droga , Humanos , Estimulação Luminosa/métodos , Fotoquimioterapia/métodos
16.
J Photochem Photobiol B ; 67(1): 64-70, 2002 May.
Artigo em Inglês | MEDLINE | ID: mdl-12007469

RESUMO

TiO2 semiconductor colloids have been successfully employed in environmental clean-up, antibacterial and bactericidal action under ultraviolet light due to its strong redox ability and high yield of active oxygen species (1O2, O2*-), *OOH) generation. Hypocrellin B, isolated from Hypocrella bambusae (B.et.Br) Sacc, a natural pigment with strong and broad absorption over the visible light region, was used in our work in an attempt to extend the photoresponse of TiO2 to visible light and maintain the high generation of active oxygen under visible light illumination. The formation of the HB-TiO2 chelate was characterized by UV-Vis and surface enhanced raman spectroscopy (SERS) and it was found that the chelate still had high efficiency of active oxygen generation. The possible generation mechanism was explored by Electron Paramagnetic Resonance (EPR) and time-resolved transient spectra techniques, showing that singlet oxygen (1O2) and superoxide radical anion (O2*-)) were produced via energy transfer and electron transfer, respectively. The application of HB-TiO2 chelate in environment protection and bacteria sterilization was implied.


Assuntos
Perileno/análogos & derivados , Perileno/química , Fármacos Fotossensibilizantes/química , Quinonas/química , Oxigênio Singlete/química , Superóxidos/química , Titânio/química , Quelantes , Coloides , Espectroscopia de Ressonância de Spin Eletrônica/métodos , Estrutura Molecular , Transtornos de Fotossensibilidade
17.
J Photochem Photobiol B ; 68(2-3): 73-8, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12468200

RESUMO

Hypocrellin B (HB) is a natural pigment with a promising application in the photodynamic therapy (PDT) for anticancer treatment. The photobleaching of HB in non-polar organic solvents and in liposomes in aqueous solution were investigated by the measurements of absorption spectra, quenching experiments and determination of photoproducts. Control experiments indicated that the sensitizer, oxygen and light were all essential for the photobleaching of HB, which suggested that it was mainly self-sensitized photooxidation. The illumination of HB with visible light in aerobic non-polar solvent generated singlet oxygen efficiently [Phi(1O(2))=0.76] which then attacked the sensitizer HB with formation of an endoperoxide product. The endoperoxide of HB was unstable at room temperature and underwent predominantly loss of singlet oxygen with regeneration of parent HB. The singlet oxygen released from the endoperoxide of HB was detected with chemical trapping experiments. When HB was embedded in EPC liposomes, no endoperoxide product and no singlet oxygen release from the photobleaching process of HB were detected. The quenching experiments indicated that the singlet oxygen mechanism (type II) played an important role in the non-polar solvent and the free radical mechanism (type I) was predominant in liposomal aqueous solution for the photobleaching of HB.


Assuntos
Lipossomos , Perileno , Perileno/análogos & derivados , Fármacos Fotossensibilizantes , Quinonas , Estrutura Molecular , Perileno/química , Fotoquimioterapia , Fármacos Fotossensibilizantes/química , Quinonas/química , Solventes , Espectrofotometria Ultravioleta
18.
J Photochem Photobiol B ; 71(1-3): 43-50, 2003 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-14705638

RESUMO

To improve hydrophilicity and photoactivity of the new type of photosensitizer, hypocrellin, two new derivatives were synthesized through a mild reaction method between hypocrellion B (HB) and ethanolamine in tetrahydrofuran (THF) and their molecular structures were characterized by IR, NMR, MS and UV-Vis spectrometry. In the molecular structures of the two derivatives, the peri-hydroxylated perylenquinone structure of the parent HB is preserved and their photoresponses at 600-900 nm (the red spectral region) are enhanced markedly (the molar absorption coefficients at 650 nm for the two new derivatives are EAHB1 log epsilon = 3.72 and EAHB2 log epsilon = 3.91, respectively. In contrast, the parent compound HB exhibits little absorption at 650 nm). Electron paramagnetic resonance (EPR) spin trapping measurement and a 9,10-diphenylanthracene (DPA) bleaching method were employed to investigate the photodynamic action of two chemicals in the presence of oxygen. The quantum yields of O2(1(delta)g) generation of EAHB1 and EAHB2 are 0.08 and 0.45, respectively; the relative quantum yields of (O2*-) generation of EAHB1 and EAHB2 are 0.15 and 0.76, respectively, with the parent compound HB as the standard.


Assuntos
Perileno/análogos & derivados , Perileno/síntese química , Quinonas/síntese química , Perileno/química , Fenol , Fotoquímica , Quinonas/química , Análise Espectral/métodos
19.
J Colloid Interface Sci ; 264(1): 290-5, 2003 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-12885548

RESUMO

The photoinduced interaction of fluorescein ester derivatives, fluorescein's butyl ester (FL4) and fluorescein's anthraquinone-methyl ester (FL-AQ), and colloidal CdS was examined by absorption, fluorescence spectroscopy, and photoinduced ESR spectroscopy. It is found that FL4 and FL-AQ molecules are adsorbed on the surfaces of CdS colloid by an electrostatic interaction forming the surface complex of the type CdS-FL4 or CdS-FL-AQ. The apparent association constant (K(app)) and the degree of association (alpha) of CdS-FL4 obtained from absorption spectra are 2.25 x 10(4) M(-1) and 0.78, respectively. The values of K(app) and alpha of CdS-FL4 as determined from fluorescence spectra are 1.54 x 10(4) M(-1) and 0.82, respectively, which matches well with that determined from the absorption spectra changes. And the values of K(app) and alpha of CdS-FL-AQ obtained from absorption spectra are 4.18 x 10(4) M(-1) and 0.83, respectively. These data indicate that there is a strong interaction between the dye and the CdS particle surface. But there was no evidence for interfacial electron transfer from FL4 or FL-AQ to colloidal CdS by photoinduced ESR experiments. The fluorescence quenching is due to the formation of a nonfluorescent complex. The related phenomena are discussed in this paper.

20.
J Colloid Interface Sci ; 263(2): 669-73, 2003 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-12909061

RESUMO

A dyad composed of fluorescein and 2-methyl-anthraquinone (FL-AQ) was synthesized and its photophysical properties were examined by absorption, fluorescence spectroscopy, and fluorescence lifetime. The charge-separated state formed by photoinduced intramolecular electron transfer was detected by nanosecond transient absorption spectroscopy for the first time. When FL is excited in solution, the photoinduced electron transfer from FL to AQ proceeds efficiently. The rate constant and the efficiency of intramolecular electron transfer are 3.95 x 10(9) s(-1) and 95%, respectively. Its charge-separated state lifetime is too short to detect by transient absorption spectroscopy. Adding nanometer colloidal TiO(2) to an FL-AQ ethanol solution prolongs the lifetime of the charge-separated state, so its transient absorption signal is recorded significantly. The lifetimes of FL(+). at 480 nm and AQ(-). at 560 nm in the FL-AQ/TiO(2) colloidal system are 11.1 and 8.93 mivros, respectively.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA