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1.
PLoS One ; 19(2): e0297487, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38412199

RESUMO

Global rises in precarious labour conditions have prompted further empirical work in Decent Work, a special category of employment characterised by equitable pay, treatment, and healthy working conditions. Despite this, research has tended to be conducted in developed countries with privileged groups such as those with typical working arrangements and rely on psychologically framed individual characteristics to explain marginalising factors. We propose a more sociologically framed, spatialised perspective on Decent Work which posits that marginalising factors are spatially variable and determined but moderated by employability empowerment. We measure our propositions across three spatially different sites of Vietnam through (1) a survey of minority ethnic students and graduates (N = 1071) and (2) a survey of stakeholders involved in the recruitment and employment of this group (N = 204). We find support for most of our propositions and call for more spatialised empirical work in the field of Decent Work.


Assuntos
Emprego , Grupos Minoritários , Humanos , Adolescente , Vietnã
2.
J Pharm Sci ; 113(7): 1885-1897, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38369022

RESUMO

The purpose of this study was to develop an in vitro release testing (IVRT) strategy to predict the pre-clinical performance of single agent and combination long acting injectable (LAI) suspension products. Two accelerated IVRT methods were developed using USP apparatus 2 to characterize initial, intermediate, and terminal phases of drug release. Initial and intermediate phases were captured using a suspension cup with moderate agitation to ensure a constant, low surface area exposure of the LAI suspension to the release media. The terminal phase was obtained by exposing the LAI suspension to a high initial paddle speed. This resulted in smaller suspension particulates with high cumulative surface area that were dispersed throughout the release media, enabling rapid drug release. The in vitro release profiles obtained with these two methods in 48 h or less were independently time scaled to reflect the in vivo time scale of approximately 1800 h. Level-A in vitro in vivo correlations (IVIVCs) were separately developed for each method and active pharmaceutical ingredient (API) using in vivo absorption profiles obtained by deconvolution of rat plasma concentration-time profiles. The IVIVCs were successfully validated for each API. This work provides a framework for evaluating individual phases of drug release of complex LAIs to ultimately predict their in vivo performance.


Assuntos
Preparações de Ação Retardada , Liberação Controlada de Fármacos , Animais , Preparações de Ação Retardada/farmacocinética , Ratos , Ratos Sprague-Dawley , Injeções , Masculino , Suspensões , Química Farmacêutica/métodos , Combinação de Medicamentos
3.
Foods ; 12(22)2023 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-38002159

RESUMO

Emerging evidence has demonstrated that using a new manufacturing technology to produce γ-aminobutyric acid (GABA)-fortified oolong (GO) tea could relieve human stress and exert versatile physiological benefits. The purpose of this human study was to investigate the therapeutic effects of daily GO tea consumption on improvements in blood pressure, relaxation-related brain waves, and quality of life (QOL) over a period of 28 consecutive days. Total polyphenols, major catechins, and free amino acids were analyzed via an HPLC assay. Changes in heart rate, blood pressure, α brain waves (index of relaxation), and the eight-item QOL score were investigated on days 0, 7, 14, 21, and 28. The chemical analysis results showed that GO tea contained the most abundant amino acids and GABA, contributing to the relaxation activity. Among all study participants, the daily consumption of GO tea could reduce systolic blood pressure on day 21 and diastolic blood pressure on day 28 (p < 0.05 for both). For participants with pre-hypertension, GO tea could effectively reduce heart rate and systolic and diastolic blood pressure on day 28 (p < 0.05). At the end of the study, incremental changes in alpha brain waves and QOL scores were also demonstrated (p < 0.05 for both). This study suggests that GO tea might potentially serve as a natural source for alternative therapy to improve blood pressure, stress relief, and QOL.

4.
Anal Methods ; 15(35): 4427-4433, 2023 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-37646200

RESUMO

Volatile amines are reagents commonly used in pharmaceutical manufacturing of intermediates, active pharmaceutical ingredients (APIs), and drug products as participating regents for chemical reactions and optimization of product yield. Due to their compound specific daily allowable intake, residual volatile amines are required by regulatory agencies to be monitored and controlled in pharmaceutical products intended for human consumption. However, the accurate quantification of residual volatile amines in pharmaceutical entities can often be challenging as these analytes may chemically react and/or interact with the sample matrix. Herein, we describe a simple and universal headspace gas chromatography with flame ionization detection (HS-GC-FID) method capable of separating 14 commonly used volatile amines. The chemical activity of the volatile amines with the API matrix were mitigated by using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as an additive to reduce matrix effects in conventional high-boiling diluents. The addition of DBU drastically improved the detectability and method accuracy of the residual volatile amines in an acidic API, namely, Ketoprofen®. Additionally, DBU was employed as a GC deactivation reagent to ensure interfacial adsorption of the analytes to GC components were reduced, thereby improving method precision. Method validation showed acceptable linearity, limit of detection, limit of quantitation, solution stability, precision, and robustness. Separation specificity, evaluated by observing the chromatographic resolution of the volatile amines with one-another and against a set of 23 common residual solvents, were shown to be acceptable for most peak pairs.


Assuntos
Aminas , Projetos de Pesquisa , Humanos , Cromatografia Gasosa , Ionização de Chama , Excipientes
5.
Int J Educ Vocat Guid ; : 1-21, 2022 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-35910080

RESUMO

This article examines how graduate employability is viewed by employers in six economically disadvantaged mountainous provinces in Vietnam. The study reported in this article identified continuous self-learning, resilience, adaptability, devotion and empathy for the local people and local community to be among the main employability attributes expected of graduates in regional Vietnam. The findings of the study raise the importance of context situatedness in looking at employability and show how employability is characterised by the local structural conditions, demographic features and socio-cultural norms. The study provides significant implications for career guidance and graduate employability development, especially in relation to regional areas.


"L'employabilité dans son contexte ¼: Attributs attendus par les employeurs·euses dans la région du Vietnam et implications pour l'orientation professionnelle Cet article examine comment l'employabilité des diplômé·e·s est perçue par les employeurs·ses dans six provinces montagneuses économiquement défavorisées du Vietnam. L'étude rapportée dans cet article a identifié l'auto-apprentissage continu, la résilience, l'adaptabilité, le dévouement et l'empathie pour la population locale et la communauté locale comme étant parmi les principaux attributs d'employabilité attendus des diplômés dans le Vietnam régional. Les résultats de l'étude soulignent l'importance de la situation du contexte dans l'étude de l'employabilité et montrent comment l'employabilité est caractérisée par les conditions structurelles locales, les caractéristiques démographiques et les normes socioculturelles. L'étude fournit des implications significatives pour l'orientation professionnelle et le développement de l'employabilité, en particulier en ce qui concerne les zones régionales.


"Empleabilidad en contexto": Atributos esperados por los empleadores en Vietnam regional e implicaciones para la orientación profesional Este artículo examina cómo los empleadores ven la empleabilidad de los graduados en seis provincias montañosas económicamente desfavorecidas de Vietnam. El estudio reportado en este artículo identificó el autoaprendizaje continuo, la resiliencia, la adaptabilidad, la devoción y la empatía por la población local y la comunidad local como uno de los principales atributos de empleabilidad que se esperan de los graduados en la región de Vietnam. Los hallazgos del estudio plantean la importancia de la situación contextual para observar la empleabilidad y muestran cómo la empleabilidad se caracteriza por las condiciones estructurales locales, las características demográficas y las normas socioculturales. El estudio proporciona implicaciones significativas para la orientación profesional y el desarrollo de la empleabilidad, especialmente en relación con las áreas regionales.

6.
Heliyon ; 8(8): e10141, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-36039131

RESUMO

Purpose: This study aims to develop and propose an integrated conceptual framework that illustrates how emerging technologies such as mobile augmented reality applications (MAR apps) stimulate a user's immersive MAR app-enhanced experience-a human psychological state of being engaged and engrossed in a virtual environment-which in turn facilitates user responses. Design/methodology/approach: This study draws on a literature review of related fields to develop a theoretical model showing the centrality of the immersive MAR app-enhanced experience. Findings: A conceptual model that explicates the selected antecedents and outcomes of the AR-enhanced immersive experience is proposed. The findings suggest that the traits of both the user (mental imagery, personal innovativeness) and the device (simulated physical control, environmental embedding) facilitate the immersive MAR app-enhanced experience. Moreover, the immersive MAR app-enhanced experience is identified as a key driver of customer emotions, values and behavioral responses. Originality/value: The integrated conceptual model provides scholars and practitioners with a general picture of the main factors affecting the immersive AR-enhanced experience, as well as the benefits available to firms; thus, theoretical and practical implications are delineated. Paper type: Conceptual paper.

7.
Read Writ ; 35(2): 303-323, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35474713

RESUMO

Whereas cognitive and linguistic factors for learning to read have been extensively studied, less is known about affective factors including children's attitudes toward reading. Studies primarily from English-speaking and Western countries show gradual declines in reading attitudes in elementary school (McKenna et al., 1995) and a positive association between reading attitudes and achievement (Petscher, 2010). Children from Asian and African countries are underrepresented in this literature; whether these patterns can be generalized across cultures needs further investigation. This longitudinal study examined the reading attitudes of 84 children in Vietnam from grades 1 to 2 and their relations to reading performance, as measured by translated and adapted versions of the Elementary Reading Attitude Survey and Early Grade Reading Assessment, respectively. This sample from Vietnam showed a small decline in reading attitudes over time, particularly in attitudes toward academic reading. However, children on average reported feeling happy about reading in both grades. Correlations revealed different patterns of association between reading attitudes and performance based on the reading measure employed, grade level, and type of reading in question (academic versus recreational). In grade 2, reading attitudes explained unique variance in reading comprehension even after text fluency and mother's education were considered. We present a margins plot to visualize the role of reading attitudes on reading comprehension. We discuss educational implications and future directions.

8.
Opt Express ; 30(5): 7782-7792, 2022 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-35299533

RESUMO

In contrast to conventional surface-enhanced Raman scattering (SERS) platforms implemented on non-biological substrates, silk fibroin has the unique advantages of long-term biosafety and controllable biodegradability for in vitro and in vivo biomedical applications, as well as flexibility and process-compatibility. In this study, a silk fibroin film was developed to fabricate a flexible SERS sensor template with nanogap-rich gold nanoislands. The proposed biological SERS platform presents fairly good enhancements in detection performance such as detection limit, sensitivity, and signal-to-noise ratio. In particular, the sensitivity improvement was by more than 10 times compared to that of the counterpart sample, and an excellent spatial reproducibility of 2.8% was achieved. In addition, the near-field calculation results were consistent with the experimental results, and the effect of surface roughness of the silk substrate was investigated in a quantitative way. It is believed that biological SERS-active sensors could provide the potential for highly sensitive, cost-effective, and easily customizable nanophotonic platforms that include new capabilities for future healthcare devices.


Assuntos
Fibroínas , Ouro , Reprodutibilidade dos Testes , Análise Espectral Raman/métodos
9.
Environ Manage ; 69(3): 466-479, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35059809

RESUMO

Participatory mapping (PM) is a valuable research tool for assessing fire risk, especially in regions where data are difficult to collect or inconsistent; in such areas, the integration between crowdsourced data and geospatial techniques plays a fundamental role in gathering more consistent and reliable information. This study combines a participatory (community-based) mapping approach with geospatial techniques to assess fire risk in Van Chan district, northern Vietnam, an area where the economy relies mainly on forestry activities. Local stakeholders designed a map of wildfires, which was modelled as a function of a set of physical and socio-economic variables. A fire-probability map of the district was obtained and compared with MODIS data (2000-2020). The results suggest that higher fire probability occurs in areas with lower human pressure, and they provide information on related socio-economic drivers that affect this phenomenon. This study highlights the importance of combining participatory approaches and geospatial techniques to assess fire dynamics and prevent wildfires in terms of understanding and predicting the risks. The involvement of local communities is fundamental to this innovative participatory approach with regard to better supporting decision-making and prevention actions and to developing fire control management guidelines.


Assuntos
Incêndios , Incêndios Florestais , Agricultura Florestal , Florestas , Probabilidade , Vietnã
10.
Biosensors (Basel) ; 11(11)2021 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-34821657

RESUMO

Novel concepts for developing a surface-enhanced Raman scattering (SERS) sensor based on biocompatible materials offer great potential in versatile applications, including wearable and in vivo monitoring of target analytes. Here, we report a highly sensitive SERS sensor consisting of a biocompatible silk fibroin substrate with a high porosity and gold nanocracks. Our silk-based SERS detection takes advantage of strong local field enhancement in the nanoscale crack regions induced by gold nanostructures evaporated on a porous silk substrate. The SERS performance of the proposed sensor is evaluated in terms of detection limit, sensitivity, and linearity. Compared to the performance of a counterpart SERS sensor with a thin gold film, SERS results using 4-ABT analytes present that a significant improvement in the detection limit and sensitivity by more than 4 times, and a good linearity and a wide dynamic range is achieved. More interestingly, overlap is integral, and a quantitative measure of the local field enhancement is highly consistent with the experimental SERS enhancement.


Assuntos
Técnicas Biossensoriais , Fibroínas , Ouro , Nanopartículas Metálicas , Análise Espectral Raman , Porosidade
11.
Talanta ; 188: 522-530, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-30029408

RESUMO

In this work, the performances of polymeric ionic liquid (PIL) based solid-phase microextraction (SPME) coatings were assessed for applications concerning food safety and quality. Two different polymeric ionic liquid coatings, namely poly(1-4-vinylbenzyl-3-hexadecylimidazolium) bis[(trifluoromethyl)sulfonyl] imide (poly([VBHDIM][NTf2]), PIL 1, and N,N-didecyl-N-methyl-d-glucaminium poly(2-methyl-acrylic acid 2-[1-(3-{2-[2-(3-trifluoromethanesulfonylamino-propoxy)-ethoxy]-ethoxy}-propylamino)-vinylamino]-ethyl ester) (poly([DDMGlu][MTFSI]), PIL 2, were evaluated. The PIL-based coatings were compared to commercially available SPME coatings in terms of their performance toward extraction of pesticides and fruit metabolites. The partition coefficients (Kfs) of the tested coatings were calculated, with PIL 1 demonstrating similar or better performance compared to the commercial coatings. Design of experiment (DoE) was applied to optimize the parameters that most influenced SPME extraction, and a quantitative method for determination of 5 organophosphorus pesticides was developed by using PIL-based coatings and commercial SPME fibers. Despite the thin layer of the sorbent coating, PIL 1 achieved limits of quantitation at the low part-per-billion level. Moreover, in a comparative investigation of analyte coverage carried out via HS-SPME-GCxGC-ToF/MS with grape homogenate as model matrix, excellent performances were observed for the PIL-based coatings toward the determination of fruit metabolites, demonstrating their capability towards broad extractive coverage of analytes characterized by various physicochemical properties.

12.
J Pharm Biomed Anal ; 145: 879-886, 2017 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-29843206

RESUMO

In this study, two ionic liquids (ILs), 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([BMIM][NTf2]) and trihexyltetradecylphosphonium bis[(trifluoromethyl)sulfonyl]imide ([P66614][NTf2]) were examined as contemporary diluents for residual solvent analysis using static headspace gas chromatography (SHS-GC) coupled with flame ionization detection (FID). ILs are a class of non-molecular solvents featuring negligible vapor pressure and high thermal stabilities. Owing to these favorable properties, ILs have potential to enable superior sensitivity and reduced interference, compared to conventional organic diluents, at high headspace incubation temperatures. By employing the [BMIM][NTf2] IL as a diluent, a 25-fold improvement in limit of detection (LOD) was observed with respect to traditional HS-GC diluents, such as N-methylpyrrolidone (NMP). The established IL-based method demonstrated LODs ranging from 5.8 parts-per-million (ppm) to 20ppm of residual solvents in drug substances. The optimization of headspace extraction conditions was performed prior to method validation. An incubation temperature of 140°C and a 15min incubation time provided the best sensitivity for the analysis. Under optimized experimental conditions, the mass of residual solvents partitioned in the headspace was higher when using [BMIM][NTf2] than NMP as a diluent. The analytical performance was demonstrated by determining the repeatability, accuracy, and linearity of the method. Linear ranges of up to two orders of magnitude were obtained for class 3 solvents. Excellent analyte recoveries were obtained in the presence of three different active pharmaceutical ingredients. Owing to its robustness, high throughput, and superior sensitivity, the HS-GC IL-based method can be used as an alternative to existing residual solvent methods.


Assuntos
Cromatografia Gasosa/métodos , Contaminação de Medicamentos , Imidazóis/química , Líquidos Iônicos/química , Preparações Farmacêuticas/química , Solventes/análise , Sulfonamidas/química , Ionização de Chama , Indometacina/química , Limite de Detecção , Pirrolidinonas/química , Quinidina/química
13.
J Chromatogr A ; 1449: 2-7, 2016 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-27157428

RESUMO

This study describes a simple and rapid sampling method employing a polymeric ionic liquid (PIL) sorbent coating in direct immersion solid-phase microextraction (SPME) for the trace-level analysis of acrylamide in brewed coffee and coffee powder. The crosslinked PIL sorbent coating demonstrated superior sensitivity in the extraction of acrylamide compared to all commercially available SPME coatings. A spin coating method was developed to evenly distribute the PIL coating on the SPME support and reproducibly produce fibers with a large film thickness. Ninhydrin was employed as a quenching reagent during extraction to inhibit the production of interfering acrylamide. The PIL fiber produced a limit of quantitation for acrylamide of 10µgL(-1) and achieved comparable results to the ISO method in the analysis of six coffee powder samples.


Assuntos
Acrilamida/análise , Coffea/química , Café/química , Líquidos Iônicos/química , Polímeros/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Pós , Microextração em Fase Sólida/métodos
14.
Ther Innov Regul Sci ; 49(6): 890-897, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30222378

RESUMO

OBJECTIVE: To compare consumer preferences for a revised and current acetaminophen over-the-counter "Drug Facts" labels (ODFL) on warnings and self-reported correct intended action following signs of overdose. METHODS: Adults visiting a community center were randomly assigned to revised or current ODFLs using previously reported label comprehension methodology. RESULTS: Participant (N = 110) ratings for both ODFLs were comparable for ease of finding and understanding information. In response to an emergent overdose scenario, the proportion reporting the correct intended action using the revised ODFL was significantly greater than the proportion using the current ODFL (91% [97.5% CI, 0.82-0.99] vs. 76% [97.5% CI, 0.64-0.89]). In side-by-side comparisons, the revised ODFL was superior for overall consumer preference, usefulness for first-time use, and better overdose-related directions. A revised bottle cap statement also outperformed the current statement used on brand acetaminophen. CONCLUSION: Findings support revision of acetaminophen ODFLs to improve liver damage warnings and to optimize labeling likely to be useful in prevention of and response to overdose.

15.
Nanoscale Res Lett ; 9(1): 596, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25392706

RESUMO

This paper aims to investigate the light output power (LOP) of InGaN-based light-emitting diodes (LEDs) grown on patterned sapphire substrates (PSSs) with different symmetry. The GaN epitaxial layers grown on the hexagonal lattice arrangement PSS (HLAPSS) have a lower compressive strain than the ones grown on the square lattice arrangement PSS (SLAPSS). The quantum-confined Stark effect (QCSE) is also affected by the residual compressive strain. Based on the experimentally measured data and the ray tracing simulation results, the InGaN-based LED with the HLAPSS has a higher LOP than the one with the SLAPSS due to the weaker QCSE within multiple-quantum wells (MQWs).

16.
Anal Chim Acta ; 843: 18-26, 2014 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-25150693

RESUMO

Super elastic nitinol (NiTi) wires were exploited as highly robust supports for three distinct crosslinked polymeric ionic liquid (PIL)-based coatings in solid-phase microextraction (SPME). The oxidation of NiTi wires in a boiling (30%w/w) H2O2 solution and subsequent derivatization in vinyltrimethoxysilane (VTMS) allowed for vinyl moieties to be appended to the surface of the support. UV-initiated on-fiber copolymerization of the vinyl-substituted NiTi support with monocationic ionic liquid (IL) monomers and dicationic IL crosslinkers produced a crosslinked PIL-based network that was covalently attached to the NiTi wire. This alteration alleviated receding of the coating from the support, which was observed for an analogous crosslinked PIL applied on unmodified NiTi wires. A series of demanding extraction conditions, including extreme pH, pre-exposure to pure organic solvents, and high temperatures, were applied to investigate the versatility and robustness of the fibers. Acceptable precision of the model analytes was obtained for all fibers under these conditions. Method validation by examining the relative recovery of a homologous group of phthalate esters (PAEs) was performed in drip-brewed coffee (maintained at 60 °C) by direct immersion SPME. Acceptable recoveries were obtained for most PAEs in the part-per-billion level, even in this exceedingly harsh and complex matrix.

17.
J Chromatogr A ; 1361: 217-28, 2014 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-25151038

RESUMO

Ionic liquids (ILs) were used as a new class of diluents for the analysis of two classes of genotoxic impurities (GTIs), namely, alkyl/aryl halides and nitro-aromatics, in small molecule drug substances by headspace gas chromatography (HS-GC) coupled with electron capture detection (ECD). This novel approach using ILs as contemporary diluents greatly broadens the applicability of HS-GC for the determination of high boiling (≥ 130°C) analytes including GTIs with limits of detection (LOD) ranging from 5 to 500 parts-per-billion (ppb) of analytes in a drug substance. This represents up to tens of thousands-fold improvement compared to traditional HS-GC diluents such as dimethyl sulfoxide (DMSO) and dimethylacetamide (DMAC). Various ILs were screened to determine their suitability as diluents for the HS-GC/ECD analysis. Increasing the HS oven temperatures resulted in varying responses for alkyl/aryl halides and a significant increase in response for all nitroaromatic GTIs. Linear ranges of up to five orders of magnitude were found for a number of analytes. The technique was validated on two active pharmaceutical ingredients with excellent recovery. This simple and robust methodology offers a key advantage in the ease of method transfer from development laboratories to quality control environments since conventional validated chromatographic data systems and GC instruments can be used. For many analytes, it is a cost effective alternative to more complex trace analytical methodologies like LC/MS and GC/MS, and significantly reduces the training needed for operation.


Assuntos
Cromatografia Gasosa/métodos , Elétrons , Líquidos Iônicos/química , Mutagênicos/análise , Bibliotecas de Moléculas Pequenas/química , Cromatografia Gasosa/instrumentação , Limite de Detecção , Temperatura
18.
J Chromatogr A ; 1346: 1-7, 2014 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-24786655

RESUMO

Solid-phase microextraction (SPME) using cross-linked polymeric ionic liquid (PIL)-based sorbent coatings was used to extract volatile aroma-related compounds from coffee samples. Several PIL-based coatings were screened alongside a commercial poly(acrylate) (PA) SPME coating. The best performing PIL-based SPME fiber, poly(1-vinyl-3-hexadecylimidazolium bis[(trifluoromethyl)sulfonylimide]) with 50% (w/w) 1,12-di(3-vinylbenzylimidazolium)dodecane dibis[(trifluoromethyl)sulfonyl]imide incorporated cross-linker, was used to isolate the volatile fraction of Arabica coffee. To illustrate the importance of trace analyte isolation, a method for the detection and quantification of coffee adulteration is described. Chromatographic profiles obtained by gas chromatography/mass spectrometry (GC/MS) were used to create the chemometric model. Partial least squares (PLS) regression was employed to correlate the aroma-related chemical fingerprint to the degree of adulteration. The proposed method successfully detected fraud down to 1% (w/w) of adulterant and accurately determined the degree of coffee adulteration (i.e, root mean square error of calibration and prediction of 0.54% and 0.83% (w/w), respectively). Finally, important aroma-related compounds including furans, methoxyphenols, pyrazines, and ketones were identified.


Assuntos
Coffea/química , Tecnologia de Alimentos/métodos , Cromatografia Gasosa-Espectrometria de Massas , Líquidos Iônicos/química , Microextração em Fase Sólida , Qualidade dos Alimentos , Polímeros/química , Análise de Regressão
19.
Mol Cell Proteomics ; 13(6): 1485-94, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24692643

RESUMO

Type 1 fimbriae are filamentous structures on Escherichia coli. These structures are important adherence factors. Because binding to the host cells is the first step of infection, type 1 fimbria is an important virulence factor of pathogenic E. coli. Expression of type 1 fimbria is regulated by a phase variation in which each individual bacterium can alternate between fimbriated (phase-ON) and nonfimbriated (phase-OFF) states. The phase variation is regulated by the flipping of the 314-bp fimS fragment, which contains the promoter driving the expression of the genes required for the synthesis of type 1 fimbria. Thus, the bacterial proteins able to interact with fimS are likely to be involved in regulating the expression of type 1 fimbria. To identify novel type 1 fimbria-regulating factors, we used an E. coli K12 proteome chip to screen for the bacterial factors able to interact with a 602-bp DNA fragment containing fimS and its adjacent regions. The Spr protein was identified by the proteome chip-based screening and further confirmed to be able to interact with fimS by electrophoretic mobility shift assay. Deletion of spr in the neonatal meningitis E. coli strain RS218 significantly increased the ratio of the bacterial colonies that contained the type 1 fimbria phase-ON cells on agar plates. In addition, Spr interfered with the interactions of fimS with the site-specific recombinases, FimB and FimE, which are responsible for mediating the flipping of fimS. These results suggest that Spr is involved in the regulation of type 1 fimbria expression through direct interaction with the invertible element fimS. These findings facilitate our understanding of the regulation of type 1 fimbria.


Assuntos
Proteínas de Bactérias/biossíntese , Fímbrias Bacterianas/genética , Proteoma/genética , Fatores de Virulência/biossíntese , DNA Nucleotidiltransferases/biossíntese , Escherichia coli K12/genética , Regulação Bacteriana da Expressão Gênica , Regiões Promotoras Genéticas , Proteoma/biossíntese , Recombinação Genética , Fatores de Virulência/genética
20.
Talanta ; 121: 153-62, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24607122

RESUMO

The extraction performance of four polymeric ionic liquid (PIL)-based solid-phase microextraction (SPME) coatings has been studied and compared to that of commercial SPME coatings for the extraction of 16 volatile compounds in cheeses. The analytes include 2 free fatty acids, 2 aldehydes, 2 ketones and 10 phenols and were determined by headspace (HS)-SPME coupled to gas chromatography (GC) with flame-ionization detection (FID). The PIL-based coatings produced by UV co-polymerization were more efficient than PIL-based coatings produced by thermal AIBN polymerization. Partition coefficients of analytes between the sample and the coating (Kfs) were estimated for all PIL-based coatings and the commercial SPME fiber showing the best performance among the commercial fibers tested: carboxen-polydimethylsyloxane (CAR-PDMS). For the PIL-based fibers, the highest K(fs) value (1.96 ± 0.03) was obtained for eugenol. The normalized calibration slope, which takes into account the SPME coating thickness, was also used as a simpler approximate tool to compare the nature of the coating within the determinations, with results entirely comparable to those obtained with estimated K(fs) values. The PIL-based materials obtained by UV co-polymerization containing the 1-vinyl-3-hexylimidazolium chloride IL monomer and 1,12-di(3-vinylimiazolium)dodecane dibromide IL crosslinker exhibited the best performance in the extraction of the select analytes from cheeses. Despite a coating thickness of only 7 µm, this copolymeric sorbent coating was capable of quantitating analytes in HS-SPME in a 30 to 2000 µg L(-1) concentration range, with correlation coefficient (R) values higher than 0.9938, inter-day precision values (as relative standard deviation in %) varying from 6.1 to 20%, and detection limits down to 1.6 µg L(-1).


Assuntos
Queijo/análise , Líquidos Iônicos , Polímeros/química , Microextração em Fase Sólida/métodos , Compostos Orgânicos Voláteis/análise
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