Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 33
Filtrar
Mais filtros

Tipo de documento
Intervalo de ano de publicação
1.
Climacteric ; 23(1): 84-92, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31365272

RESUMO

Objectives: Considering that bio-psycho-sociocultural variables influence menopause, this research aimed to assess the suitability of the self-regulation model in explaining the menopausal experience, and to explore differences among participants with different characteristics (e.g. health, sexual related) regarding menopause representations.Methods: Overall, 27 Portuguese women aged 40-65 years were assessed for sociodemographics, health, and sexual activity, as well as menopausal status and symptoms. Semi-structured in-depth interviews were conducted. A directed content analysis was performed, and the qualitative data presented. Afterward, the frequencies of the categories were analyzed through quantitative methods (Mann-Whitney U tests).Results: Aging was the most frequently mentioned feature regarding menopause Identity, whereas vasomotor symptoms were the most mentioned regarding Negative Consequences and menses cessation regarding Positive Consequences. Features related to Cause (hormonal changes) and Control (need for acceptance) of menopause were also identified. No differences were found in the frequency of menopause representations between women with different characteristics (e.g. with higher vs. lower vasomotor symptom severity).Conclusion: The suitability of the self-regulation model to explain these women's menopause experience was confirmed and the representations did not vary among participants with different characteristics. This research might help professionals and researchers in developing comprehensive interventions, based on this theoretical model.


Assuntos
Atitude Frente a Saúde , Menopausa/psicologia , Autocontrole/psicologia , Adulto , Envelhecimento/psicologia , Feminino , Humanos , Menopausa/fisiologia , Pessoa de Meia-Idade , Portugal , Pesquisa Qualitativa , Autorrelato
3.
Phys Chem Chem Phys ; 19(8): 6206-6215, 2017 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-28230216

RESUMO

Amphiphilic and lipophilic donor-acceptor naphthalimide-oligothiophene assemblies exhibiting almost identical intramolecular properties, but differing in their intermolecular interactions, have been synthesized. Here we analyze the effect of replacing the normally used lipophilic alkyl chains with hydrophilic ones in directing molecular aggregation from an antiparallel to a parallel stacking. This different molecular packing of the amphiphilic, NIP-3TAmphi, and lipophilic, NIP-3TLipo, systems is assessed by electronic spectroscopies, scanning electronic microscopy and DFT quantum-chemical calculations. Theoretical calculations indicate that the presence of amphiphilic interactions promotes a face-to-face parallel arrangement of neighbor molecules, which induces improved electronic coupling and therefore enhances the charge transport ability and photoconducting properties of this type of materials. Time of flight and photoconducting measurements are used to determine the impact of the amphiphilic and lipophilic interactions on their possible performance in optoelectronic devices.

4.
Sci Total Environ ; 912: 169454, 2024 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-38123101

RESUMO

Using reclaimed water for agricultural irrigation is increasing worldwide to compensate for water scarcity. The aim of this work was to evaluate the uptake of some of the most commonly detected organic contaminants of emerging concern (CECs) and pesticides in regenerated water in a field study. Furthermore, it was studied their distribution and accumulation in the different parts of a crop (soil, plant and fruit). Three crops (cucumber, pepper and melon) were grown under controlled agronomic conditions in a greenhouse. In order to make an accurate evaluation of the process, "regenerated blank water" was spiked with 70 chemicals (including antibiotics, anti-inflammatories, analgesics, anaesthetics, anxiolytics, anticonvulsants, pesticides) at environmental concentrations (∼1 µg/L) and used for continuous crop irrigation. After crop season, the average total concentration of contaminants detected in the soil samples ranged from 132 to 232 µg/kg d.w depending of the crops type. Between 7 and 10 different contaminants were found in the harvested fruits, up to levels of 27.8 µg/kg f.w. cucumber, 12.4 µg/kg f.w. melon and 7.8 µg/kg f.w pepper. In general, cucumber fruit showed higher accumulation levels of contaminants than pepper and melon for most target analytes. The accumulation rates followed the order: root (0.2 %) < stem/leaf (1-4 %) < fruit (1-6 %) < soil (17-30 %). The experimental data obtained in this study were also used to assess the risk associated with the reuse of reclaimed water for crop irrigation as well to identify those contaminants that, due to their physicochemical properties, show higher accumulation rates and environmental impact.


Assuntos
Cucumis sativus , Praguicidas , Água , Produtos Agrícolas , Agricultura , Irrigação Agrícola , Solo
5.
Anal Bioanal Chem ; 402(2): 935-43, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22033822

RESUMO

Due to the basic properties of nicotine, it is not easily integrated into commonly used multiresidue methods. The present work investigates the application of two commonly employed multiresidue methods-the QuEChERS method and the ethyl acetate method-for determining nicotine in mushrooms. Both methods are employed in a modified form and an unmodified form: the former to address the special properties of nicotine and the latter, combined with the use of isotopically labelled nicotine, to compensate for poor recoveries. The QuEChERS-based methods were followed by liquid chromatography-time-of-flight mass spectrometry and those based on ethyl acetate extraction were followed by gas chromatography-triple quadrupole-mass spectrometry. All methods were validated according to European guidelines (document no. SANCO/10684/2009). Recovery studies performed on mushroom spiked at 10 and 100 µg kg(-1) yielded average recoveries in the range 80-110% with relative standard deviation (RSD) values below 9%. The linearity of the response over two orders of magnitude was demonstrated (r(2) > 0.995) for all of the determination techniques employed. The limits of detection and quantification obtained were in the 0.7 and 10 µg kg(-1) range, depending on the technique, and thus below the maximum residue level established for this toxic alkaloid by current EU legislation. Good repeatability and reproducibility were obtained in terms of the RSD of the analytical methods (0.4-13.2%). The modified QuEChERS method was tested in a proficiency test on nicotine in dried mushrooms obtaining good results. The methods were successfully applied to 20 real samples.


Assuntos
Agaricales/química , Nicotina/análise , Cromatografia Líquida de Alta Pressão , Cromatografia Gasosa-Espectrometria de Massas , Espectrometria de Massas , Reprodutibilidade dos Testes
6.
Sci Total Environ ; 806(Pt 4): 150909, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34653474

RESUMO

Using reclaimed water to irrigate crops can be an important route for organic contaminants of emerging concern (CECs) to be introduced into agricultural production and thus find their way into the food chain. This work aims to establish accumulation models for the different parts of a crop (fruit/leaves/roots) and the soil of some of the most commonly detected CECs in reclaimed water, through field trials in greenhouses. For this, tomato plants were permanently irrigated under realistic agricultural conditions with a mixture of the selected compounds at approx. 1 µg/L. A total of 30 contaminants were analyzed belonging to different compound categories. A modified QuEChERS extraction method followed by liquid chromatography coupled to tandem mass spectrometry was the procedure used. The study revealed the presence of 21 target contaminants in the tomatoes, and 18 CECs in the leaves, roots, and soil. The average total concentration of pesticides detected in the tomatoes was 3 µg/kg f.w., whereas the average total load of pharmaceuticals was 5.8 µg/kg f.w. after three months, at the time of crop harvesting. The levels of pharmaceutical products and pesticides in the non-edible tissues were up to 3.5 and 2.1 µg/kg f.w., respectively, in the leaves and up to 89.3 and 31.3 µg/kg f.w., respectively, in the roots. In the case of the soil samples, the pesticide concentration found after crop harvesting was below 11.4 µg/kg d.w., and less than 3.0 µg/kg d.w. for pharmaceuticals. Overall, the concentration levels of CECs detected in the tomatoes, which were permanently irrigated with contaminated reclaimed water, do not pose a risk to human health via dietary intake.


Assuntos
Solanum lycopersicum , Poluentes Químicos da Água , Irrigação Agrícola , Cromatografia Líquida , Humanos , Espectrometria de Massas em Tandem , Águas Residuárias/análise , Água , Poluentes Químicos da Água/análise
7.
Sci Total Environ ; 782: 146759, 2021 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-33838369

RESUMO

In this study, we aimed to develop and validate a quick, easy, and robust extraction method for the simultaneous determination of 30 organic contaminants of emerging concern (CECs) including some transformation products in soil samples. Three different extraction methods based on an ultrasonic cylindrical probe (UAE), a pressurized liquid extraction (PLE), and a QuEChERS method were compared. Ultra-performance liquid chromatography coupled with electrospray tandem mass spectrometry (LC-MS/MS) was used for identification and quantification of the target analytes. A modified QuEChERS method showed the best results in terms of extractability and accuracy. The extraction procedure developed provided adequate extraction performances (70% of the target analytes were recovered within a 70-99% range), with good repeatability and reproducibility (variations below 20%) and great sensitivity (LOQ < 0.1 ng/g in most cases). No matrix effects were observed for 70% of the compounds. Finally, the analytical methodology was applied in a pilot study where agricultural soil was irrigated with reclaimed water spiked with the contaminants under study. Of the 25 CECs added in irrigation water, a total of 13 pesticides and 5 pharmaceutical products were detected at concentration ranges from 0.1 to 1.2 ng/g (d.w) and from 0.1 to 2.0 ng/g (d.w), respectively.

8.
Anal Methods ; 13(36): 4131-4142, 2021 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-34554152

RESUMO

In this study, we aimed to validate and apply a quick and easy extraction method for the simultaneous determination of 27 pesticide residues at trace levels in agricultural samples (soil, fruit, and leaf) to monitor the presence of these contaminants released from reclaimed water. The procedure was based on a salting-out extraction method with acidified acetonitrile, followed by a dispersive solid-phase extraction (d-SPE) clean-up step applying the C18 sorbent. Ultra-performance liquid chromatography coupled with electrospray tandem mass spectrometry (LC-MS/MS) was used for identification and quantification of the target analytes. This methodology provided recovery values higher than 70%, for all pesticides and matrices evaluated in the study, except for propamocarb in soil samples (35%). Repeatability and reproducibility results, calculated as relative standard deviations (RSD, %), ranged between 1% and 18% in both cases. No remarkable matrix effects were observed for vegetable samples, except for thiamethoxam in red cabbage, and hexythiazox in carrot and leaves (between 30 and 40%). Soil samples showed a moderate matrix effect (between 21 and 35%) for more than 80% of the compounds. Monitoring pesticide residues found in agricultural samples irrigated with contaminated reclaimed water under controlled conditions revealed the efficacy of the proposed method. Three common vegetables were grown to evaluate the different migration and distribution rates in crops and soil. Pesticide accumulation in the different parts of the crop (soil, fruit, and leaves) and the potential human exposure to pesticides through daily intake were also discussed.


Assuntos
Resíduos de Praguicidas , Cromatografia Líquida , Humanos , Resíduos de Praguicidas/análise , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem , Água
9.
J Nanosci Nanotechnol ; 10(2): 1148-52, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-20352770

RESUMO

One of the factors that limit the efficiency of polymer-based optoelectronic devices, such as photovoltaic solar cells and light emitting diodes, is the exciton diffusion within the polymeric network. Due to the amorphous nature the of polymeric materials, the diffusion of excitons is limited by the energetic and spatial disorder in such systems, which is a consequence not only of the chemical structure of the polymer but also from its morphology at nanoscale. To get a deep understanding on how such effects influence exciton dynamics we performed a quantum molecular dynamics simulations to determine the energetic disorder within the polymer system, and Monte Carlo simulations to study exciton diffusion in three-dimensional (3D) polymer networks that present both spatial and energetic disorder at nanometre scale. Our results show clearly that exciton diffusion in poly(p-phenylenevinylene) (PPV) occurs preferentially in the direction parallel to the electrodes surface for a polymer-based optoelectronic devices with the orientation of the conjugated strands similar to those obtained by the spin-coating technique and the decay of such excitons occurs preferentially in longer strands which allow us to get insight on exciton behaviour in polymeric systems that are not possible to be obtained directly from the experiments.

10.
Sci Total Environ ; 647: 232-244, 2019 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-30081361

RESUMO

This study reports an analytical approach by gas chromatography and high-resolution mass spectrometry (HRMS) intended to be used for investigation of non-targeted environmental contaminants in honeybees. The approach involves a generic extraction and analysis with two GC-HRMS systems: time-of-flight and Orbitrap analyzers, GC-TOF-MS, and GC-Orbitrap-MS operated in electron-impact ionization (EI) mode. The workflow for screening of non-targeted contaminants consisted of initial peak detection by deconvolution and matching the first-stage mass spectra EI-MS with a nominal mass spectral library. To gain further confidence in the structural characterization of the contaminants under investigation, molecular formula of representative ions (molecular and fragment ions) was provided for those with an accurate mass scoring (error < 5 ppm). This methology was applied for screening environmental contaminants in 75 samples of adult honeybee. This approach has provided the tentative identification of environmental contaminants belonging to different chemical groups, among them, PAHs, phthalates and synthetic musks. Residues of veterinary treatments used in apiculture were also detected in the honeybee samples.


Assuntos
Abelhas/química , Monitoramento Ambiental/métodos , Poluentes Ambientais/análise , Animais , Cromatografia Gasosa-Espectrometria de Massas , Espectrometria de Massas , Compostos Orgânicos/análise , Hidrocarbonetos Policíclicos Aromáticos/análise
11.
J Chromatogr A ; 1573: 28-41, 2018 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-30224277

RESUMO

Spices are known as difficult matrices that contain variable amounts of fats, piperine or many other matrix constituents. The increasing sensitivity of new GC-MS/MS platforms opens new approaches to analyze pesticide residue in complex matrices such as spices, by sample dilution. The aim of this work is to develop and validate an effective multiresidue method for the analysis of pesticide residues in spices by GC-MS/MS. In this paper, we highlight the importance of reducing matrix interferences generated from co-extractive components of spices. Moreover, we emphasize the concern of obtaining clean extracts requiring less instrument maintenance. By evaluating the total ion chromatograms (TIC) on GC-Orbitrap-MS of different extracts using various sorbents, QuEChERS citrate using EMR-Lipid sorbent resulted in the cleanest extract among Z-Sep, Primary secondary amine (PSA), Oasis® Prime HLB, and Supelclean™ Ultra cartridges that consist of a top bed of PSA, C18 and Grashsphere™ 2031 and a bottom bed of Z-Sep. Later, the analyses were performed on a GC-QQQ-MS/MS, applying a 15 min runtime method covering 205 compounds. The samples were diluted 25 times before the injection bearing in mind that the instrumental LOQs reached (iLOQ) were 2 ng g-1 and the method LOQs (mLOQ) were 50 ng g-1. Good recoveries between 70 and 120% with RSDs lower than 20% were observed for 90% of the compounds in black pepper and for 83% of the compounds in cayenne pepper. To demonstrate the applicability of the proposed method, 50 real dried and non-dried spice samples were analyzed. The most detected pesticides were metalaxyl, chlorpyrifos, tebuconazole, ethion, and chinomethionate.


Assuntos
Análise de Alimentos/métodos , Cromatografia Gasosa-Espectrometria de Massas , Técnicas de Diluição do Indicador , Lipídeos/química , Resíduos de Praguicidas/análise , Especiarias/análise , Extração em Fase Sólida
12.
Phys Med Biol ; 52(10): 2703-17, 2007 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-17473346

RESUMO

Human dental enamel has a porous mesostructure at the nanometre to micrometre scales that affects its thermal and mechanical properties relevant to laser treatment. We exploit finite-element models to investigate the response of this mesostructured enamel to mid-infrared lasers (CO(2) at 10.6 microm and Er:YAG at 2.94 microm). Our models might easily be adapted to investigate ablation of other brittle composite materials. The studies clarify the role of pore water in ablation, and lead to an understanding of the different responses of enamel to CO(2) and Er:YAG lasers, even though enamel has very similar average properties at the two wavelengths. We are able to suggest effective operating parameters for dental laser ablation, which should aid the introduction of minimally-invasive laser dentistry. In particular, our results indicate that, if pulses of approximately 10 micros are used, the CO(2) laser can ablate dental enamel without melting, and with minimal damage to the pulp of the tooth. Our results also suggest that pulses with 0.1-1 micros duration can induce high stress transients which may cause unwanted cracking.


Assuntos
Esmalte Dentário/efeitos da radiação , Raios Infravermelhos/efeitos adversos , Lasers/efeitos adversos , Modelos Biológicos , Esmalte Dentário/patologia , Análise de Elementos Finitos , Humanos , Terapia a Laser , Porosidade , Água/química
13.
Chemosphere ; 184: 1310-1319, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28679151

RESUMO

This work presents a non-targeted screening approach for the detection and quantitation of contaminants in bees and pollen, collected from the same hive, by GC-EI-ToF-MS. It consists of a spectral library datasets search using a compound database followed by a manual investigation and analytical standard confirmation together with semi-quantitation purposes. Over 20% of the compounds found automatically by the library search could not be confirmed manually. This number of false positive detections was mainly a consequence of an inadequate ion ratio criterion (±30%), not considered in the automatic searching procedure. Eight compounds were detected in bees and pollen. They include insecticides/acaricides (chlorpyrifos, coumaphos, fluvalinate-tau, chlorfenvinphos, pyridaben, and propyl cresol) at a concentration range of 1-1207 µg kg-1, herbicides (oxyfluorfen) at a concentration range of 212-1773 µg kg-1 and a growth regulator hormone (methoprene). Some compounds were detected only in pollen; such as herbicides (clomazone), insecticides/acaricides and fungicides used to control Varroa mites as benzylbenzoate, bufencarb, allethrin, permethrin, eugenol and cyprodinil. Additional compounds were detected only in bees: flamprop-methyl, 2-methylphenol (2-49 µg kg-1) and naphthalene (1-23 µg kg-1). The proposed method presents important advantages as it can avoid the use of an unachievable number of analytical standards considered target compounds "a priori" but not present in the analyzed samples.


Assuntos
Abelhas/química , Monitoramento Ambiental/métodos , Poluentes Ambientais/análise , Pólen/química , Testes de Toxicidade/métodos , Acaricidas/análise , Animais , Cresóis , Fungicidas Industriais/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Herbicidas/análise , Mel/análise , Inseticidas/análise , Nitrilas , Piretrinas
14.
Environ Sci Pollut Res Int ; 23(5): 4609-20, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26527334

RESUMO

This study reports an analytical approach intended to be used for investigation of non-targeted environmental contaminants and to characterize the organic pollution pattern of bee wax comb samples. The method comprises a generic extraction followed by detection with gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC-TOF-MS), operated in electron impact ionization (EI) mode. The screening approach for the investigation of non-targeted contaminants consisted of initial peak detection by deconvolution and matching the first-stage mass spectra EI-MS(1) with a nominal mass spectral library. To gain further confidence in the structural characterization of the contaminants under investigation, the molecular formula of representative ions (molecular ion when present in the EI spectrum) and, for at least other two fragment ions, was provided for those with an accurate mass scoring (mass error < 5 ppm). This methodology was applied for screening environmental contaminants in 50 samples of bee wax comb. This approach has allowed the tentative identification of some GC-amenable contaminants belonging to different chemical groups, among them, phthalates and polycyclic aromatic hydrocarbons (PAHs), along with residues of veterinary treatments used in apiculture.


Assuntos
Abelhas , Poluição Ambiental/análise , Cromatografia Gasosa-Espectrometria de Massas , Mel/análise , Animais , Cromatografia Gasosa-Espectrometria de Massas/métodos , Hidrocarbonetos Policíclicos Aromáticos/análise
15.
J Chromatogr A ; 1426: 161-73, 2015 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-26654830

RESUMO

Several clean-up methods were evaluated for 253 pesticides in pollen samples concentrating on efficient clean-up and the highest number of pesticides satisfying the recovery and precision criteria. These were: (a) modified QuEChERS using dSPE with PSA+C18; (b) freeze-out prior to QuEChERS using dSPE with PSA+C18; (c) freeze-out prior to QuEChERS using dSPE with PSA+C18+Z-Sep; and (d) freeze-out followed by QuEChERS using dSPE with PSA+C18 and SPE with Z-Sep. Determinations were made using LC-MS/MS and GC-MS/MS. The modified QuEChERS protocol applying a freeze-out followed by dSPE with PSA+C18 and SPE clean-up with Z-Sep was selected because it provided the highest number of pesticides with mean recoveries in the 70-120% range, as well as relative standard deviations (RSDs) typically below 20% (12.2% on average) and ensured much better removal of co-extracted matrix compounds of paramount importance in routine analysis. Limits of quantification at levels as low as 5µgkg(-1) were obtained for the majority of the pesticides. The proposed methodology was applied to the analysis of 41 pollen bee samples from different areas in Spain. Pesticides considered potentially toxic to bees (DL50<2µg/bee) were detected in some samples with concentrations up to 72.7µgkg(-1), which could negatively affect honeybee health.


Assuntos
Abelhas , Resíduos de Praguicidas/análise , Pólen/química , Animais , Cromatografia Líquida/métodos , Extração em Fase Sólida , Espanha , Espectrometria de Massas em Tandem/métodos
16.
Acad Med ; 73(4): 436-8, 1998 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9580724

RESUMO

PURPOSE: To examine the attitudes of physicians practicing in New Mexico toward gay and lesbian medical students, house officers, and physician colleagues. METHOD: In May 1996, the authors mailed a questionnaire with demographic and attitude questions to 1,949 non-federally employed physicians practicing in New Mexico. The questionnaire consisted of questions dealing with medical school admission, residency training, and referrals to colleagues. The response rate was 53.6%. RESULTS: Of all the responding physicians, 4.3% would refuse medical school admission to applicants known to be gay or lesbian. Respondents were most opposed to gay and lesbian physicians' seeking residency training in obstetrics and gynecology (10.1%), and least opposed to their seeking residency training in radiology (4.3%). Disclosure of homosexual orientation would also threaten referrals to gay and lesbian obstetrician-gynecologists (11.4%) more than to gay or lesbian physicians in other specialties. CONCLUSION: Physicians' attitudes toward gay and lesbian medical students, house officers, and physician colleagues seem to have improved considerably from those reported previously in the literature. However, gay men and lesbians in medicine continue to face opposition in their medical training and in their pursuit of specialty practice.


Assuntos
Atitude do Pessoal de Saúde , Homossexualidade Feminina , Homossexualidade Masculina , Médicos , Distribuição de Qui-Quadrado , Educação Médica , Medicina de Emergência/educação , Medicina de Família e Comunidade/educação , Feminino , Ginecologia/educação , Humanos , Medicina Interna/educação , Internato e Residência , Relações Interprofissionais , Masculino , Corpo Clínico Hospitalar , New Mexico , Obstetrícia/educação , Pediatria/educação , Radiologia/educação , Encaminhamento e Consulta , Critérios de Admissão Escolar , Especialização , Especialidades Cirúrgicas/educação , Estudantes de Medicina , Inquéritos e Questionários , Urologia/educação
17.
J Colloid Interface Sci ; 436: 132-7, 2014 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-25268816

RESUMO

In this work we report on the permittivity of suspensions of elongated goethite particles in silicone oils of different viscosities. In spite of the low conductivity of the systems, the electrode polarization is significant. To correct this phenomenon, the procedure chosen is the one called logarithmic derivative of the real part of the permittivity, and it proves to efficiently reduce the effect of electrodes to the extent that the spectra of pure liquids are flat in the accessible frequency range (20 Hz-1 MHz). In our suspensions, we observe the presence of a dielectric relaxation for frequencies in the range 4-40 kHz. In principle, such relaxations might be ascribed to the Maxwell-Wagner (MW) polarization. However, it is found that both the characteristic frequency and the relaxation amplitude of the suspensions increase with volume fraction, something unexpected for an MW relaxation. Such discrepancy can be explained by considering the Frenkel-Trukhan model, which reproduces the Maxwell-Wagner results in conditions of thin electrical double layers (which it is not our case). An excellent agreement is found between our data and the model predictions, using only the particle surface charge as a parameter.

18.
J Chromatogr A ; 1287: 24-37, 2013 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-23535633

RESUMO

This work reviews the current state-of-the-art of liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) techniques applied to the analysis of pesticides in fruit-based and vegetable-based matrices. Nowadays, simultaneous trace analysis of hundreds of pesticides from different classes is required, preferably in just one run. The most commonly used QqQ-MS technology presents certain limitations in its application in a cost and effective way when analyzing a large number of pesticides. Thus, this review includes HRMS technology as a reliable complementary alternative allowing the analysis of a wide range of pesticides in food. Its capabilities and limitations in identifying, confirming and quantifying pesticides are discussed. HRMS instruments can adequately address such issues; however, the main drawbacks are as a result of insufficient prior optimization of the operational parameters during non-target analysis in full-scan mode and due to software shortcomings.


Assuntos
Cromatografia Líquida/métodos , Frutas/química , Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/química , Verduras/química
19.
Shock ; 40(3): 203-9, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23846411

RESUMO

INTRODUCTION: It has been shown that the innate immune system mediates acute lung inflammation triggered by intestinal trauma. Sexual dimorphism modulates the profile of TH1 and TH2 lymphocytes, and accordingly sex hormones may modulate acute lung inflammation by intestinal ischemia/reperfusion (I/R). Studies indicate that female rats are relatively resistant to organ injury caused by hemorrhagic shock and that the gut of female is more resistant than that of the male to deleterious effects of ischemic injury. At the present study, we investigated the effect of estradiol (E(2)) on the lung inflammation after intestinal I/R and its interaction with the nitric oxide (NO) pathway. METHODS: Anesthetized female rats submitted or not to 7 days ovariectomy (OVx) were subjected to occlusion of the superior mesenteric artery during 45 min, followed by 2 h of reperfusion. Groups of rats were treated with E(2) (17ß-estradiol, 280 µg/kg, s.c.) 24 h before ischemia and/or with the nonselective NO synthase inhibitor L-NAME (Nω-nitro-L-arginine methyl ester hydrochloride) (5 mg/kg, i.v.). In a parallel set of experiments, the selective NO synthase inhibitor, aminoguanidine (50 mg/kg i.v.), was given 1 h before ischemia. In all groups, lung vascular permeability (LVP) was assessed using the Evans blue dye extravasation method, neutrophil recruitment to the tissues by the standard myeloperoxidase (MPO) method, and endothelial NO synthase (eNOS) protein expression by Western blot. RESULTS: In OVx rats, LVP and MPO were increased after intestinal I/R as compared with intact controls. Estradiol reverted the LVP, but not MPO. Aminoguanidine reduced LVP in OVx rats. The E(2) protective effect on LVP was abolished by L-NAME; moreover, an increase in LVP even when compared with OVx rats treated only with L-NAME was observed. In addition, lung eNOS protein expression was reduced in OVx-I/R rats in comparison to intact controls and the E(2) inhibited this effect. CONCLUSIONS: Estradiol treatment is able to reduce lung inflammation due to intestinal I/R, but with the concomitant blockade of NOS activity, this effect is abolished. Nitric oxide probably reduces the vascular deleterious effects of intestinal I/R, and E(2) pretreatment reduces lung inflammation after intestinal I/R and exerts these effects by modulating eNOS protein expression in the lungs.


Assuntos
Estradiol/uso terapêutico , Intestinos/irrigação sanguínea , Óxido Nítrico/metabolismo , Pneumonia/tratamento farmacológico , Pneumonia/metabolismo , Animais , Feminino , Masculino , Ratos , Ratos Wistar
20.
Nanotechnology ; 23(40): 405605, 2012 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-22997179

RESUMO

In this work, the influence of air pressure during the annealing of Ge quantum dot (QD) lattices embedded in an amorphous Al(2)O(3) matrix on the structural, morphological and compositional properties of the film is studied. The formation of a regularly ordered void lattice after performing a thermal annealing process is explored. Our results show that both the Ge desorption from the film and the regular ordering of the QDs are very sensitive to the annealing parameters. The conditions for the formation of a void lattice, a crystalline Ge QD lattice and a disordered QD lattice are presented. The observed effects are explained in terms of oxygen interaction with the Ge present in the film.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA