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OBJECTIVES: To investigate the prevalence of depression and anxiety symptoms among older adults in an urban district in China, as well as their associated factors. DESIGN: Cross-sectional study. SETTING: General communities in Shenzhen, Guangdong, China. PARTICIPANTS: A total of 5372 community-dwelling older adults aged 65 years or older were initially recruited. Ultimately, 5331 participants met the inclusion criteria and were included in this study. METHODS: Participants completed a sociodemographic questionnaire, along with assessments including the Patient Health Questionnaire-9, Generalised Anxiety Scale-7, UCLA Loneliness Simplification Scale, Insomnia Severity Index Scale (ISI), Community Dementia Brief Screening Scale and the 8-item Dementia Screening Questionnaire. Statistical analyses included the Shapiro-Wilk test, independent t-test, Wilcoxon rank test, χ2 test and univariate and multivariate linear regression analysis. RESULTS: The prevalence of depression and anxiety symptoms among older adults in Shenzhen communities was 10.4% and 11.3%, respectively. In multivariate analysis, age (B=-0.01, p<0.05), relatively poor health status in the past year (B=1.00, p<0.01), poor health status in the past year (B=2.40, p<0.01), ISI score (B=0.21, p<0.01), -item Ascertain Dementia Questionnaire (AD8) score (B=0.22, p<0.01), UCLA Loneliness Scale (ULS) score (B=0.24, p<0.01) were significantly associated with the severity of depression symptom, Compared with their respective reference categories, relatively poor health status in the past year (B=0.50, p<0.01), poor health status in the past year (B=1.32, p<0.01), ISI score (B=0.23, p<0.01), sleep duration (B=0.05, p<0.01), AD8 score (B=0.21, p<0.01), Community Screening Instrument for Dementia score (B=0.13, p<0.01), ULS score (B=0.22, p<0.01) were significantly associated with the severity of anxiety symptom. CONCLUSIONS: We observed a high prevalence of depression and anxiety symptoms among older adults in this study. The existing welfare system and infrastructure should remain and targeted mental health programmes addressing the identified risk factors should be proposed.
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Demencia , Depresión , Humanos , Anciano , Estudios Transversales , Prevalencia , Depresión/psicología , Ansiedad/psicología , China/epidemiología , Demencia/epidemiologíaRESUMEN
The influence of frying times (0, 2, 4, 6, 8, and 10 min) on the continuous changes in the water distribution and the concentrations of key volatile compounds in chicken breast during the frying process were studied. The fried chicken samples could be distinguished by PCA of E-nose and PLS-DA of GC-MS. A total of 40 volatile compounds were identified by GC-MS, and 28 compounds were verified to be the key compounds after further screening by OAVs. The T22 was increased first and then decreased, while the M22 and M23 in fried chicken were considerably decreased and increased with increasing frying time, respectively. The content of the water and the total peak area of LF-NMR in fried chicken samples during the frying process significantly decreased, and the water was transferred from high to low degrees of freedom. In addition, water content, T21, T22, M22 and L* value were positively correlated with most alcohols and aldehydes, and were negatively correlated with pyrazines, while a*, b*, M23 and all amino acids were positively correlated with pyrazines and were negatively correlated with most alcohols and aldehydes. The results may guide the production processes of fried chicken and help produce high-quality chicken products.
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Aldehídos , Pollos , Animales , Aldehídos/análisis , Alcoholes/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos , PirazinasRESUMEN
Nian zhuan has its aroma as one of the perceived principal characteristics. The current study was aimed mainly to investigate the potential to include the aroma of nian zhuan as a new target criterion into the green wheat product chain. By improving the conditions for the traditional processing of nian zhuan, the optimal processing conditions were determined as green wheat (GW) 14 d, steaming the green wheat with the skin (SGWS) 26 min and cooked green wheat peeled (CGWP) 280 min, to evaluate the feasibility of using electronic nose (E-nose) and gas chromatography mass spectrometry (GC-MS) to discriminate nian zhuan in different stages. E-nose was used to recognize nian zhuan odors in different processing stages, and GC-MS to identify the individual volatile compounds. A total of 139 volatile compounds were detected by GC-MS, of which 71 key were screened by t-test (P < 0.01). The W1W, W1S, W2W and W2S sensors of E-nose gave higher responses to all samples, and effectively discriminated the samples. The most volatile compounds were produced in the millstone milling (MSM) stage of nian zhuan, and millstone could promote the release of volatile compounds from cooked green wheat by milling.
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The effects of stir-frying stages on the formation of flavor volatile compounds, Maillard reaction products (MRPs) and potentially hazardous substances with time in stir-fried beef sao zi were investigated. A total of 122 volatile compounds were identified in beef sao zi after stir-frying. Most of the volatile compounds were produced in the stir-frying fat (SFF) process of beef sao zi. Furosine, fluorescence intensity, Nε-(1-Carboxymethyl)-L-lysine (CML), Nε-(1-Carboxyethyl)-L-lysine (CEL) polyaromatic hydrocarbons (PAHs), heterocyclic aromatic amines (HAAs) and acrylamides (AA) are mainly presented in stir-fried beef sao zi. The furosine peaked at MSF 120 s as the Maillard reaction progressed. The fluorescent compound gradually increased with time during the stir-frying process. The CML and CEL peaked at MSF 120 s. AA reached its maximum in MSF 90 s and then decreased. The quantities and content of HAAs and PAHs were increased by prolonging the stir-frying time, but ended up far lower than the maximum permissible value specified by the Commission of the European Communities. The extended stir-frying promoted MRPs and some hazardous substances, but the content of potentially hazardous substances was still within the safety range for stir-frying beef sao zi.
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Productos Finales de Glicación Avanzada , Lisina , Animales , Bovinos , China , Sustancias Peligrosas , Reacción de MaillardRESUMEN
The effects of stir-frying stage and time on the formation of Maillard reaction products (MRP) and potentially hazardous substances with time in stir-fried mutton sao zi were investigated. Furosine, fluorescence intensity, Nε-(1-carboxymethyl)-L-lysine (CML), Nε-(1-carboxyethyl)-L-lysine (CEL), polyaromatic hydrocarbons PAHs), heterocyclic aromatic amines (HAAs), and acrylamides (AA) mainly presented were of stir-fried mutton sao zi. The furosine decreased after mixed stir-frying (MSF) 160 s due to its degradation as the Maillard reaction (MR) progressed. The fluorescent compound gradually increased with time during the stir-frying process. The CML and CEL peaked in MSF at 200 s. AA reached its maximum at MSF 120 s and then decreased. All the 5 HAAs were detected after MSF 200 s, suggesting that stir-frying mutton sao zi was at its best before MSF for 200 s. When stir-frying exceeded the optimal processing time of (MSF 160 s) 200 s, the benzo[a]pyrene peaked at 0.82 µg/kg, far lower than the maximum permissible value specified by the Commission of the European Communities. Extended stir-frying promoted MRP and some hazardous substances, but the content of potentially hazardous substances was still within the safety range for food.
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Tan lamb is highly recommended breed in China. It is of great significance to understand the underlying mechanism of how water-soluble flavor precursors metabolize in Tan lamb muscles during the postmortem aging period. In this study, we investigated the muscle pH, lactate dehydrogenase (LDH) activity, and the variations in water-soluble flavor-related metabolites. The proteome changes were profiled to provide insights into the biochemical changes affecting accumulation of water-soluble flavor precursors in different aging stages (days 0, 4, and 8). The results indicated that pH value considerably decreased from day 0 to day 4, and increased from day 4 to day 8 (p < .05). The activity of LDH significantly increased from day 0 to day 4, and decreased from day 4 to day 8 (p < .05). Postmortem glycolysis was activated in 4 days, which directly affected the variations in metabolic enzymes and triggered the accumulation of flavor-related carbohydrates. The free amino acids accumulated due to hydrolysis of structural proteins, with 3-hydroxy-L-proline, aspartic acid, and methionine increasing from day 0 to day 4, and aspartic acid, serine, threonine, tyrosine, phenylalanine, and D-phenylalanine from day 4 to day 8. The inosine and hypoxanthine accumulated due to the degradation of ATP. The results of the present study provide insightful information, revealing the differences in biochemical attributes in Tan lamb muscles caused by postmortem aging.
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INTRODUCTION: The objective of this study was to explore the gender differences of community-dwelling patients with schizophrenia in terms of socio-demographics, clinical characteristic and quality of life (QOL). METHODS: A total of 433 community-dwelling patients with schizophrenia were recruited in Shenzhen city, China. Data were obtained from a face-to-face interview with standard research questionnaire. The QOL and insight were assessed using the WHOQOL-BREF and the Chinese version of the insight and treatment attitude questionnaire, respectively. RESULTS: This cross-sectional study included 206 male and 227 female patients. Male patients were more likely to be educated, employed, smoking cigarettes and drinking alcohol, and have an early age of illness onset. In contrast, female patients were more likely to be married/cohabitating and have drug side effects. There was no significant difference between genders across all QOL domain. Multiple regression analyzes showed that mental symptoms were negatively associated with all QOL domains, whereas frequency of exercise in the past year was positively associated with all QOL domains. Higher education levels, household per capita annual income in past year (≥100 000 RMB), employment status, IATQ score, drug side effects, marital status, and number of hospitalization were also significantly associated with specific QOL domains. DISCUSSION: There was significant gender difference in socio-demographics and clinical characteristics among community schizophrenia patients in Shenzhen city. Gender-specific intervention measures are needed to improve the functioning and QOL in patients with schizophrenia.
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Calidad de Vida , Esquizofrenia , Estudios Transversales , Femenino , Humanos , Masculino , Esquizofrenia/epidemiología , Factores Sexuales , Encuestas y CuestionariosRESUMEN
OBJECTIVES: To investigate the gender disparities in the prevalence and severity of depressive and anxiety symptoms and associated factors among internal migrant workers in Shenzhen. DESIGN: Cross-sectional study. SETTING: Labour intensive factories in Shenzhen, Guangdong, China. PARTICIPANTS: We recruited 3200 internal migrant workers who aged over 18 years old and above and did not register in Shenzhen's household registration system. There were 3095 participants eligible for this study. METHODS: Participants completed sociodemographic questionnaire, the Patient Health Questionnaire-9, the Generalized Anxiety Disorder-7, the UCLA Loneliness Scale, the Barratt Impulsiveness Scale, the Social Support Rating Scale, the Simplified Coping Style Questionnaire and Meaning in Life Questionnaire. We applied χ2 test, analysis of variance, Wilcoxon rank test, Fisher's exact test and univariate and multivariate multilevel linear regression analysis. RESULTS: The overall prevalence of depressive and anxiety symptoms was 27.85% and 19.26% among internal migrant workers. We reported gender disparities of depressive and anxiety symptoms among participants that the prevalence of depressive and anxiety symptoms was higher in women (30.57% vs 26.43% and 22.67% vs 17.47%), and the symptoms were more severe among women. Female migrant workers were more likely to be singled, have lower prevalence of smoking and drinking, receive less education and monthly income, have higher level of impulsiveness and social support and lower level of meaning in life. We found age, marriage, income, adaption to living in Shenzhen, being discriminated, drinking, loneliness, impulsiveness, social support, coping strategies and meaning of life were associated with the severity of depressive and anxiety symptoms among internal migrant workers in Shenzhen. CONCLUSION: Gender inequality may be the institutional factor leading to disparities in depressive and anxiety symptoms among internal migrant workers. Interventions should be embedded with strategies improving gender equality.
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Migrantes , Adulto , Ansiedad/epidemiología , Trastornos de Ansiedad , China/epidemiología , Estudios Transversales , Depresión/epidemiología , Femenino , Humanos , Persona de Mediana Edad , Prevalencia , Encuestas y CuestionariosRESUMEN
Surface-imprinted polymers supported by hydroxyapatite (HAP@MIPs) were prepared using coumarin-3-carboxylic acid and naringenin as dummy template molecules of zearalenone (ZEA). HAP@MIPs were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, particle size distribution analysis, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The adsorption performance was studied. The results showed that it could reach the adsorption equilibrium within 6 min. The adsorption amount could reach 6.77 µg mg-1, while the concentration was 20 µg mL-1. The self-made solid-phase extraction (SPE) columns were prepared with HAP@MIPs as sorbents for the separation and purification of ZEA in cereal samples. The method was established by high-performance liquid chromatography (HPLC). The recoveries were in the range of 70.09-101.88%; the relative standard deviation was 2.06-8.47%. Finally, millet, coix lachryma, and corn were placed under extreme conditions to produce ZEA. The method was used to extract and analyze ZEA in the above samples. The results showed that self-made SPE columns with HPLC could be used for the separation and enrichment of ZEA in real samples. Graphical abstract.
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Durapatita/química , Grano Comestible/química , Impresión Molecular/métodos , Polímeros/química , Zearalenona/aislamiento & purificación , Adsorción , Cromatografía Líquida de Alta Presión/métodos , Coix/química , Mijos/química , Extracción en Fase Sólida/métodos , Zea mays/químicaRESUMEN
Zearalenone (ZEA) is a fungal contaminant widely found in grains. In cereal samples, trace zearalenone was extracted and enriched using magnetic-surfaced pseudo molecularly imprinted polymers (SPMIPs) and detected. SPMIPs were prepared with Fe3O4 as the magnetic core, modified halloysites nanotubes as supporting materials, and selective imprinted polymers as shells. Vinyl was modified on the surface of halloysites nanotube. SPMIPs were synthesized with pseudo templates. SPMIPs as the adsorbent of dispersed-solid phase extraction (µ-SPE) were used to purify and enrich ZEA from maize samples. After optimized, the pretreatment method was evaluated. The linearity of the method was ranged within 10-200â¯ngâ¯mL-1. LOD and LOQ were 2.5â¯ngâ¯mL-1 and 8â¯ngâ¯mL-1 respectively. The ZEA spiking recoveries in maize samples ranged within 74.95-88.41% were with good RSDs lower than 4.25%. The developed method was successful applied in maize, oat, and wheat sample treatments and compared.
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Avena/química , Grano Comestible/química , Impresión Molecular/métodos , Polímeros/química , Triticum/química , Zea mays/química , Zearalenona/química , Adsorción , Cromatografía Líquida de Alta Presión , Magnetismo , Extracción en Fase Sólida/métodosRESUMEN
BACKGROUND: Internal migrant workers in the service industry are an important population in China, but the sleep quality of this population has not been well studied. The aims of the present study were to examine the prevalence of poor sleep quality among internal migrant workers in the service industry, explore the risk factors associated with poor sleep quality, and assess the correlation between insomnia and psychiatric factors. METHODS: We conducted a cross-sectional study in Shenzhen, a migrant city in China. The respondent-driven sampling (RDS) method was used to recruit participants. Sociodemographic data and physical and psychiatric health status were investigated using questionnaires. In total, 1756 internal migrant workers completed the questionnaires. The Chinese version of the Pittsburgh Sleep Quality Index (PSQI) was used to assess sleep quality, the General Anxiety Disorder-7 (GAD-7) and Center for Epidemiologic Studies Depression (CES-D) scales were used to assess anxiety and depression, respectively. Mental resilience was assessed by the Chinese version of the Connor-Davidson Resilience Scale (CD-RISC). Regression analysis was used to identify the risk factors of poor sleep quality. A structural equation model (SEM) was used to analyze the relationships among sleep, anxiety, depression and resilience. RESULTS: The prevalence of poor sleep quality among internal migrant workers in the service industry was 25.4%. Multivariate regression analysis revealed that participants who were older (OR = 1.452), worked >8 h per day (OR = 1.553), had experienced physical illness in the past 2 weeks (OR = 3.631) and had psychiatric problems such as anxiety (OR = 1.695-3.331) and depression (OR = 1.437) had an increased risk of poor sleep quality (P < 0.05). Moreover, the risk of poor sleep quality increased as the severity of anxiety increased. We also detected sex-specific risk factors and depression associated with sleep quality in women (OR = 1.480, P < 0.05) but not in men. The SEM showed that sleep was mutually correlated with anxiety (r = 0.277, P < 0.001), depression (r = 0.301, P < 0.001), and resilience (r = -0.103, P < 0.001). Resilience was mutually correlated with anxiety (r = -0.179, P < 0.001) and depression (r = -0.222, P < 0.001). CONCLUSIONS: Our study indicated that poor sleep quality was common among internal migrant workers in the service industry. Older age, long working hours, and poor physical and psychiatric health status contributed to poor sleep quality. Compared to males, sleep quality in females was more likely to be impacted by depression. Optimum working hours and physical and psychological health are critical to improving sleep quality. Interventions for ameliorating sleep quality might have different priorities for males and females.
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Ansiedad/epidemiología , Pueblo Asiatico/estadística & datos numéricos , Depresión/epidemiología , Salud Mental/estadística & datos numéricos , Trastornos del Inicio y del Mantenimiento del Sueño/epidemiología , Sueño/fisiología , Migrantes/psicología , Adulto , Anciano , Ansiedad/psicología , Trastornos de Ansiedad/epidemiología , Pueblo Asiatico/psicología , China/epidemiología , Estudios Transversales , Femenino , Estado de Salud , Humanos , Masculino , Persona de Mediana Edad , Vigilancia de la Población , Prevalencia , Factores de Riesgo , Encuestas y CuestionariosRESUMEN
A surface imprinted polymer of type UiO-66-NH2@MIP was prepared by combining molecular imprinted polymers (MIPs) and an amino-functionalized zirconium-based metal-organic framework. Quercetin is used as the virtual template, UiO-66-NH2 acts as the carrier to which the monomer acrylamide can be copolymerized. The material was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. It was used as a sorbent in a solid-phase extraction column. The extraction conditions were optimized. The adsorption capacities for aflatoxins AFB1, AFB2, AFG1 and AFG2 by this SPE and by the commercial SPE were compared. The method was successfully applied to quantify the aflatoxins in grain. Figures of merit include (a) good linearity (range from 0.20-45 µg·kg-1) with R2 (range from 0.9986-0.9994), (b) low detection limits (90-130 ng·kg-1), (c) acceptable reproducibility (1.0-5.9%; for n = 6), and (d) relatively satisfactory recovery rates (74.3-98.6%). The new sorbent has good selectivity and reusability. Graphical abstractUiO-66-NH2@MIPs were synthesized with modified UIO-66-NH2 as core and quercetin as pseudo template. A cartridge was prepared with the polymers as the sorbent, and its performance was compared with different commercial SPE cartridges.
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Aflatoxinas/aislamiento & purificación , Aminas/química , Estructuras Metalorgánicas/química , Impresión Molecular , Polímeros/química , Circonio/química , Adsorción , Aflatoxinas/química , Tamaño de la Partícula , Propiedades de Superficie , Triticum/químicaRESUMEN
Surface molecularly imprinted polymers (MIL-101@MIPs) were prepared using MIL-101 as supporting core, imprinted polymers as selective shell synthesized with coumarin-3-carboxylic acid as dummy template of Zearalenone (ZEN), methacrylic acid as functional monomer, and ethylene glycol dimethacrylate hydroxyethyl methacrylate as cross-linker. The polymers were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and particle-size distribution analyses. MIL-101@MIPs were used as the sorbent to compose the self-made cartridge. The cartridge was used to purify and enrich ZEN from real samples. Under optimized SPE conditions, a self-made cartridge can be reused for at least seven cycles. Elution was monitored with a high-performance liquid chromatography-fluorescence detection system. The linearity of the method ranged within 6.25-250 ng kg-1. The limits of detection ranged within 2.09 - 4.16 ng kg-1, and the limits of quantification ranged within 6.25 -12.50 ng kg-1, respectively. The matrix effects of four real samples were discussed. The spiking recoveries of ZEN ranged within 81.70%-90.10% with relative standard deviations lower than 5.56%. The performance of the self-made cartridge and immunoaffinity column was compared by chromatography.
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Grano Comestible/química , Polímeros/síntesis química , Extracción en Fase Sólida/métodos , Zearalenona/aislamiento & purificación , Adsorción , Cromatografía Líquida de Alta Presión , Cumarinas/química , Límite de Detección , Estructuras Metalorgánicas/química , Metacrilatos/química , Impresión Molecular , Oryza/química , Polímeros/química , Triticum/química , Zea mays/química , Zearalenona/análisisRESUMEN
In this work, a highly selective surface molecular imprinted polymers (FDU-12@MIPs) were prepared using structural analogues of aflatoxins as the template molecule and mesoporous silica FDU-12 as the carrier. The resulting polymers were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and attenuated total reflection Fourier transform infrared spectrometer. A highly ordered mesoporous nanostructure was observed in the fabricated polymer. Results showed that the adsorption capacity of FDU-12@MIPs for aflatoxins were higher than that of non-imprinted mesoporous silica polymer (FDU-12@NIPs). FDU-12@MIPs were successfully used as a solid-phase extraction sorbent coupled with HPLC for aflatoxin G2, G1, B2 and B1 determination in food samples. Under optimized conditions, recoveries from the spiked cereals were found to be 82.6%-116.7%, with relative standard deviations ranging from 2.73 to 4.21. The detection limits of aflatoxin G2, G1, B2 and B1 were estimated to be 0.05⯵gâ¯kg-1, 0.06⯵gâ¯kg-1, 0.06⯵gâ¯kg-1 and 0.05⯵gâ¯kg-1, respectively. Limits of quantifications were estimated to be 0.15⯵gâ¯kg-1, 0.2⯵gâ¯kg-1, 0.2⯵g kg-1and 0.15⯵gâ¯kg-1, respectively. The developed method exhibited a favorable linear response toward aflatoxin G2, G1, B2 and B1 in the range of 0.1⯵gâ¯kg-1-50⯵gâ¯kg-1, R2 is 0.9992-0.9996. These results indicated that FDU-12@MIPs could be used as an efficient adsorbent of solid phase extraction for enrichment of aflatoxins in real samples.
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A core consisting of nanoporous carbon (MNPC) and magnetized with Co3O4 was coated with a molecularly imprinted polymer (MIP) by atom transfer radical precipitation polymerization. Ethyl 3-coumarincarboxylate was used as a pseudo-template to give a MIP that has a fairly specific recognition capability for aflatoxins. Batch rebinding studies were carried out to determine the specific adsorption equilibrium and specific recognition. Extraction is achieved in a single step by mixing and vortexing the sample extract with the Co-MNPC@MIP. The loaded nanosorbent was then magnetically separated and eluted with acetonitrile/water (6/4, v/v). The aflatoxins were then quantified by HPLC. Under optimal conditions, the detection limits for aflatoxins typically are 0.05-0.07 ng mL-1, recoveries from spiked corn are found to be 75.1 to 99.4%, and relative standard deviations range from 1.7 to 5.1 (n = 6). Graphical abstract Poly(methacrylic acid) was imprinted with the pseudo-template ethyl 3-coumarincarboxylate by atom transfer radical precipitation polymerization on the surface of cobalt-derived magnetic nanoporous carbon (Co-MNPC). This nanosorbent was used for the magnetic solid phase extraction of aflatoxins, followed by HPLC analysis.
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Aflatoxinas/aislamiento & purificación , Carbono/química , Imanes/química , Impresión Molecular , Nanoporos , Polímeros/síntesis química , Extracción en Fase Sólida/métodos , Aflatoxinas/análisis , Aflatoxinas/química , Cobalto/química , Límite de Detección , Óxidos/química , Polimerizacion , Polímeros/químicaRESUMEN
Decarboxylative alkylation or acylation reactions of simple pyrimidines have been developed in aqueous media. Using aliphatic carboxylic acids or 2-oxocarboxylic acids and pyrimidines as substrates and silver as the catalyst, the 4-substituted alkyl or acyl pyrimidines were isolated in moderate to good yields.
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Ácidos Carboxílicos/química , Pirimidinas/síntesis química , Plata/química , Catálisis , Descarboxilación , Estructura Molecular , Pirimidinas/química , Agua/químicaRESUMEN
A novel electrogenerated chemiluminescence (ECL) assay for sensitive determination of thrombin is designed employing CdSe/ZnS quantum dots served as an ECL label. This ECL sensor is fabricated on graphene modified glassy carbon electrode which is then covered with a low surface coverage of gold nanoparticles (AuNPs). An aptamer is used to selectively recognize the target. The thiol-terminated aptamer is first immobilized on AuNPs/graphene modified electrode, and then thrombin is imported to form the aptamer-thrombin complexes. After blocking the nonspecifically bound oligonucleotides with MCH solution, another CdSe/ZnS quantum dots modified aptamer is hybridized with the free thiol-terminated aptamer to form a DNA complexe. A decreased ECL signal is observed upon recognition of the target thrombin. The integrated ECL intensity versus the concentration of thrombin is linear in the range from 0.01 to 50 nM. The detection limit is 10 fM. The present aptasensor also exhibits excellent selectivity, stability and reusability. This sensing system can provide a promising label-free model for aptamer-based compounds sensitive detection.
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Aptámeros de Nucleótidos/química , Técnicas Biosensibles/métodos , Oro/química , Grafito/química , Nanopartículas/química , Trombina/análisis , Compuestos de Cadmio/química , Carbono/química , Electrodos , Humanos , Mediciones Luminiscentes/métodos , Puntos Cuánticos , Compuestos de Selenio/química , Sensibilidad y Especificidad , Sulfuros/química , Compuestos de Zinc/químicaRESUMEN
Molecularly imprinted microspheres (MIMs) were prepared by precipitation polymerization for the binding and recognition of 1,4-hydroxybenzoic acid esters. Ethyl p-hydroxybenzoate (EtPHB) was used as the template molecule, methacrylic acid as the functional monomer, ethylene dimethacrylate as the linking agent. It was evaluated by solid-phase extraction column packed with MIMs combined with liquid chromatography to determine trace preservatives including benzoic acid, methyl p-hydroxybenzoate, EtPHB, propyl p-hydroxybenzoate in food products. A solid-phase extraction based on MIM procedure was used to isolate four additives from the food matrix before quantitative analysis. The Scatchard plot suggested that the template-polymer system had two-site binding behavior with the dissociation constants of 0.3577 and 3.952 mg/g, respectively. The rebinding test, based on the molecularly imprinted solid-phase extraction column technique, showed the recoveries of soy samples spiked with four additives within 88.4-110.6%, with the relative standard deviations of 1.97-3.82%. Finally, the method was successfully applied for the analysis of parabens in foodstuff without traditional pretreatment.