Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 54
Filtrar
1.
Rev. esp. anestesiol. reanim ; 70(8): 447-457, Octubre 2023. graf, tab
Artigo em Espanhol | IBECS | ID: ibc-225927

RESUMO

Introducción La simulación médica está asociada a emociones intensas, que influyen en el comportamiento humano. Nuestro objetivo fue investigar el modo en que el prebriefing repercute en las emociones de los alumnos durante una sesión de simulación de alta fidelidad (SAF). Métodos Estudio controlado aleatorizado prospectivo. Se asignó aleatorizadamente a los participantes para recibir un prebriefing estandarizado (grupo PE) o no recibirlo (grupo NPE). Se utilizó en ambos grupos el debriefing tras el enfoque de «buen juicio», estructurado en fases de reacciones, comprensión y resumen. A fin de evaluar las emociones, utilizamos el modelo circunflejo de afecto aplicando la escala Affect grid antes del prebriefing, tras el desempeño del caso y tras el debriefing. También se evaluaron los tiempos de debriefing. Resultados Participaron 128 facultativos en el estudio (64 frente a 64). Tras el desempeño del caso, la experiencia de esta sesión de SAF reflejó emociones significativamente más agradables en comparación con el nivel basal, que se mantuvieron durante el debriefing (p<0,01), mientras que el nivel de alerta se incrementó tras el desempeño del caso y disminuyó tras el debriefing (p<0,01). No se encontraron diferencias estadísticamente significativas entre los grupos. En el grupo NPE, los tiempos totales del debriefing (p=0,003) y de la fase de comprensión (p=0,002) fueron significativamente más prolongados. Conclusiones La experiencia de esta sesión de SAF fue agradable y con elevado nivel de alerta, sin impacto emocional específico atribuible al prebriefing, lo que da lugar a un debriefing con un flujo más libre. (AU)


Introduction Medical simulation is associated with intense emotions which influence human behavior. We aim to investigate how prebriefing impacts on learnerś emotions during a high-fidelity simulation (HFS) session. Methods This is a prospective randomized controlled study. Participants were randomly allocated to receive a standardized prebriefing (SP group) versus not receiving it (NSP group). Debriefing following the «good judgment» approach, structured in reactions, understanding and summary phases, was used in both groups. In order to assess emotions, we used the circumplex model of affect applying the Affect Grid scale, which was performed prior to prebriefing, following case performance and following debriefing. Debriefing times were also assessed. Results A total of 128 physicians participate in the study (64 vs. 64). Following case performance, this HFS session was experienced with significantly more pleasant emotions compared to baseline, that were maintained during debriefing (P<0.01) while alertness increased after case performance diminishing after debriefing (P<0.01). There were no statistical significant differences between groups. In the NSP group, total debriefing (P=0.003) and understanding phase (P=0.002) times were significantly longer. Conclusions This HFS session was experienced as pleasant with high alertness with no specific emotional impact attributable to prebriefing. Prebriefing leads to a freer flowing debriefing. (AU)


Assuntos
Humanos , Emoções , 28574 , Estudantes de Medicina/psicologia
2.
Rev Esp Anestesiol Reanim (Engl Ed) ; 70(8): 447-457, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37673209

RESUMO

INTRODUCTION: Medical simulation is associated with intense emotions which influence human behavior. We aim to investigate how prebriefing impacts on learners' emotions during a high-fidelity simulation (HFS) session. METHODS: This is a prospective randomized controlled study. Participants were randomly allocated to receive a standardized prebriefing (SP group) versus not receiving it (NSP group). Debriefing following the «good judgment¼ approach, structured in reactions, understanding and summary phases, was used in both groups. In order to assess emotions, we used the circumplex model of affect applying the Affect Grid scale, which was performed prior to prebriefing, following case performance and following debriefing. Debriefing times were also assessed. RESULTS: A total of 128 physicians participate in the study (64 vs. 64). Following case performance, this HFS session was experienced with significantly more pleasant emotions compared to baseline, that were maintained during debriefing (p < 0.01) while alertness increased after case performance diminishing after debriefing (p < 0.01). There were no statistical significant differences between groups. In the NSP group, total debriefing (p = 0.003) and understanding phase (p = 0.002) times were significantly longer. CONCLUSIONS: This HFS session was experienced as pleasant with high alertness with no specific emotional impact attributable to prebriefing. Prebriefing leads to a freer flowing debriefing.

3.
Rhinology ; 61(2): 180-189, 2023 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-36745102

RESUMO

BACKGROUND: Fibroblasts and others mesenchymal cells have recently been identified as critical cells triggering tissue-specific inflammatory responses. Persistent activation of fibroblasts inflammatory program has been suggested as an underlying cause of chronic inflammation in a wide range of tissues and pathologies. Nevertheless, the role of fibroblasts in the emergence of chronic inflammation in the upper airway has not been previously addressed. We aimed to elucidate whether fibroblasts could have a role in the inflammatory response in chronic rhinosinusitis with nasal polyps (CRSwNP). METHODOLOGY: We performed whole-transcriptome microarray in fibroblast cultured from CRSwNP samples and confirmed our results by qRT-PCR. We selected patients without other associated diseases in upper airway. To investigate shifts in transcriptional profile we used fibroblasts from nasal polyps and uncinate mucosae from patient with CRSwNP, and fibroblasts from uncinate mucosae from healthy subjects as controls. RESULTS: This study exposes activation of a pro-inflammatory and pro-fibrotic transcriptional program in nasal polyps and CRSwNP fibroblasts when compared to controls. Our Gene-set Enrichment Analysis (GSEA) pointed to common up-regulation of several pro-inflammatory pathways in patients-derived fibroblasts, along with higher mRNA expression levels of cytokines, growth factors and extracellular matrix components. CONCLUSIONS: Our work reveals a potential new source of inflammatory signaling in CRSwNP. Furthermore, our results suggest that deregulated inflammatory signaling in tissue-resident fibroblasts could support a Type-2 inflammatory response. Further investigations will be necessary to demonstrate the functionality of these novel results.


Assuntos
Pólipos Nasais , Rinite , Sinusite , Humanos , Rinite/patologia , Pólipos Nasais/patologia , Doença Crônica , Inflamação/patologia , Sinusite/metabolismo , Fibroblastos/metabolismo , Fibroblastos/patologia
4.
Nat Chem ; 14(9): 1045-1053, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35798951

RESUMO

The composition of soluble toxic protein aggregates formed in vivo is currently unknown in neurodegenerative diseases, due to their ultra-low concentration in human biofluids and their high degree of heterogeneity. Here we report a method to capture amyloid-containing aggregates in human biofluids in an unbiased way, a process we name amyloid precipitation. We use a structure-specific chemical dimer, a Y-shaped, bio-inspired small molecule with two capture groups, for amyloid precipitation to increase affinity. Our capture molecule for amyloid precipitation (CAP-1) consists of a derivative of Pittsburgh Compound B (dimer) to target the cross ß-sheets of amyloids and a biotin moiety for surface immobilization. By coupling CAP-1 to magnetic beads, we demonstrate that we can target the amyloid structure of all protein aggregates present in human cerebrospinal fluid, isolate them for analysis and then characterize them using single-molecule fluorescence imaging and mass spectrometry. Amyloid precipitation enables unbiased determination of the molecular composition and structural features of the in vivo aggregates formed in neurodegenerative diseases.


Assuntos
Amiloide , Secreções Corporais , Agregados Proteicos , Amiloide/química , Peptídeos beta-Amiloides , Secreções Corporais/química , Humanos , Agregados Proteicos/fisiologia
5.
Rev Esp Anestesiol Reanim (Engl Ed) ; 68(5): 301-303, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-34140128

RESUMO

Recently, it has been suggested that tranexamic acid should be administered only in those patients with hyperfibrinolysis determined using viscoelastic assays, as severely injured patients may present with fibrinolytic shutdown. However the last European guidelines on management of major bleeding and coagulopathy following trauma endorse the use of tranexamic acid to the trauma patient who is bleeding or at risk of significant hemorrhage as soon as possible without waiting for viscoelastic results. We present a severely blunt trauma patient treated with on-scene administration of tranexamic acid that developed immediate pulmonary embolism.


Assuntos
Antifibrinolíticos , Transtornos da Coagulação Sanguínea , Ácido Tranexâmico , Antifibrinolíticos/uso terapêutico , Fibrinólise , Hemorragia/induzido quimicamente , Humanos , Ácido Tranexâmico/uso terapêutico
6.
Rev. esp. anestesiol. reanim ; 68(5): 301-303, May. 2021.
Artigo em Espanhol | IBECS | ID: ibc-232497

RESUMO

Recientemente se ha sugerido la administración de ácido tranexámico sólo en aquellos pacientes con hiperfibrinólisis documentada con métodos viscoelásticos, ya que los pacientes politraumatizados graves pueden presentar una disminución de la fibrinólisis. Sin embargo, las últimas guías clínicas sobre el manejo de la hemorragia y coagulopatía tras un trauma recomiendan el uso de ácido tranexámico en todo paciente sangrante, o con posibilidad de sangrar, lo más precozmente posible sin esperar los resultados de los métodos viscoelásticos. Presentamos el caso de un trauma cerrado grave que recibió ácido tranexámico prehospitalariamente y desarrolló un embolismo pulmonar inmediato.(AU)


Recently, it has been suggested that tranexamic acid should be administered only in those patients with hyperfibrinolysis determined using viscoelastic assays, as severely injured patients may present with fibrinolytic shutdown. However the last European guidelines on management of major bleeding and coagulopathy following trauma endorse the use of tranexamic acid to the trauma patient who is bleeding or at risk of significant hemorrhage as soon as possible without waiting for viscoelastic results. We present a severely blunt trauma patient treated with on-scene administration of tranexamic acid that developed immediate pulmonary embolism.(AU)


Assuntos
Humanos , Masculino , Idoso de 80 Anos ou mais , Ácido Tranexâmico , Embolia Pulmonar , Fibrinólise , Hemorragia , Transtornos da Coagulação Sanguínea , Pacientes Internados , Exame Físico , Anestesiologia , Anestesia
7.
Rev Esp Anestesiol Reanim (Engl Ed) ; 68(5): 301-303, 2021 05.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-33558054

RESUMO

Recently, it has been suggested that tranexamic acid should be administered only in those patients with hyperfibrinolysis determined using viscoelastic assays, as severely injured patients may present with fibrinolytic shutdown. However the last European guidelines on management of major bleeding and coagulopathy following trauma endorse the use of tranexamic acid to the trauma patient who is bleeding or at risk of significant hemorrhage as soon as possible without waiting for viscoelastic results. We present a severely blunt trauma patient treated with on-scene administration of tranexamic acid that developed immediate pulmonary embolism.

8.
Neuropharmacology ; 166: 107964, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31954713

RESUMO

Neural activity within the ventromedial prefrontal cortex (vmPFC) is a critical determinant of stressor-induced anxiety. Pharmacological activation of the vmPFC during stress protects against stress-induced social anxiety suggesting that altering the excitatory/inhibitory (E/I) tone in the vmPFC may promote stress resilience. E/I balance is maintained, in part, by endogenous cannabinoid (eCB) signaling with the calcium dependent retrograde release of 2-arachidonoylglycerol (2-AG) suppressing presynaptic neurotransmitter release. We hypothesized that raising 2-AG levels, via inhibition of its degradation enzyme monoacylglycerol lipase (MAGL) with KML29, would shift vmPFC E/I balance and promote resilience. In acute slice experiments, bath application of KML29 (100 nM) augmented evoked excitatory neurotransmission as evidenced by a left-shift in fEPSP I/O curve, and decreased sIPSC amplitude. In whole-cell recordings, KML29 increased resting membrane potential but reduced the after depolarization, bursting rate, membrane time constant and slow after hyperpolarization. Intra-vmPFC administration of KML29 (200ng/0.5µL/hemisphere) prior to inescapable stress (IS) exposure (25, 5s tail shocks) prevented stress induced anxiety as measured by juvenile social exploration 24 h after stressor exposure. Conversely, systemic administration of KML29 (40 mg/kg, i.p.) 2 h before IS exacerbated stress induced anxiety. MAGL inhibition in the vmPFC may promote resilience by augmenting the output of neurons that project to brainstem and limbic structures that mediate stress responses.


Assuntos
Potenciais Pós-Sinápticos Excitadores/fisiologia , Monoacilglicerol Lipases/antagonistas & inibidores , Monoacilglicerol Lipases/metabolismo , Córtex Pré-Frontal/enzimologia , Estresse Psicológico/enzimologia , Estresse Psicológico/psicologia , Animais , Benzodioxóis/farmacologia , Benzodioxóis/uso terapêutico , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Masculino , Técnicas de Cultura de Órgãos , Piperidinas/farmacologia , Piperidinas/uso terapêutico , Córtex Pré-Frontal/efeitos dos fármacos , Pirazóis/farmacologia , Pirazóis/uso terapêutico , Ratos , Ratos Endogâmicos F344 , Estresse Psicológico/tratamento farmacológico
9.
Rev Esp Anestesiol Reanim (Engl Ed) ; 66(10): 521-527, 2019 Dec.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-31677738

RESUMO

INTRODUCTION: The emotional environment created during a simulation session can influence learning. Positive emotions improve perceptual processing and facilitate learning, while negative emotions can reduce working memory, resulting in poorer learning outcomes. OBJECTIVES: The aim of this study was to investigate the impact of simulation training on emotions during all phases of a high-fidelity simulation using standard prebriefing and «good judgement debriefing ¼ techniques. METHODS: This was an observational study that included 74 anesthesiologists participating in a simulation-based training. A standardized prebriefing was followed by «good judgement debriefing¼. In order to assess emotions, we used the circumplex model of emotion, and asked participants to complete the affect grid scale before prebriefing (Stage 1), before starting the simulation (Stage 2), before debriefing (Stage 3) and following debriefing (Stage 4). RESULTS: The affect grid scores obtained from 67 participants were analyzed. Following debriefing, the experience of the polytrauma patient simulation was significantly more pleasant compared to previous stages (P<0.01). In addition, participants perceived the activity as becoming increasingly active as it progressed (P<0.01). CONCLUSIONS: High-fidelity trauma simulation creating a safe environment using a standardized prebriefing and «good judgement debriefing¼ is experienced as a pleasant and active activity at all stages of the simulation. Further investigation is needed to assess the impact of these results on learning.


Assuntos
Anestesiologistas/psicologia , Emoções , Traumatismo Múltiplo/psicologia , Treinamento por Simulação/métodos , Cuidados de Suporte Avançado de Vida no Trauma/psicologia , Análise de Variância , Anestesiologistas/educação , Humanos , Traumatismo Múltiplo/terapia , Sensação
10.
Chem Sci ; 8(5): 3843-3851, 2017 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-28966776

RESUMO

A novel computational method is proposed in this work for use in discovering reaction mechanisms and solving the kinetics of transition metal-catalyzed reactions. The method does not rely on either chemical intuition or assumed a priori mechanisms, and it works in a fully automated fashion. Its core is a procedure, recently developed by one of the authors, that combines accelerated direct dynamics with an efficient geometry-based post-processing algorithm to find transition states (Martinez-Nunez, E., J. Comput. Chem.2015, 36, 222-234). In the present work, several auxiliary tools have been added to deal with the specific features of transition metal catalytic reactions. As a test case, we chose the cobalt-catalyzed hydroformylation of ethylene because of its well-established mechanism, and the fact that it has already been used in previous automated computational studies. Besides the generally accepted mechanism of Heck and Breslow, several side reactions, such as hydrogenation of the alkene, emerged from our calculations. Additionally, the calculated rate law for the hydroformylation reaction agrees reasonably well with those obtained in previous experimental and theoretical studies.

11.
Phys Chem Chem Phys ; 17(28): 18761-7, 2015 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-26119265

RESUMO

X-ray absorption near edge structure (XANES) and electrical measurements were used to elucidate the local structure and electronic changes of copper(II) oxide (CuO) nanostructures under working conditions. For this purpose, a sample holder layout was developed enabling the simultaneous analysis of the spectroscopic and electrical properties of the sensor material under identical operating conditions. The influence of different carrier gases (e.g., air and N2) on the CuO nanostructures behavior under reducing conditions (H2 gas) was studied to analyze how a particular gas atmosphere can modify the oxidation state of the sensor material in real time.

12.
Euro Surveill ; 20(14)2015 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-25884148

RESUMO

This paper analyses late presentation (LP) of HIV infection, and its determinants, among men who have sex with men (MSM) in Spain, newly diagnosed with HIV (2003-2011) in 15 sexually transmitted infection/HIV counselling and testing clinics. LP was defined as <350 CD4 cells/µL or AIDS. In total, 3,081 MSM were included (2,499 having CD4/AIDS); overall LP was 25.3%. LP was higher in men older than 34 years, those not previously HIV-tested (adjusted odds ratio (aOR):3.1; 95% confidence intervals (CI):2.3-4.2) , and those tested > 12 months before diagnosis (12-24 months (aOR:1.4; 95% CI:1.0-2.0); > 24 months (aOR:2.2; 95% CI:1.7-3.0)). LP was less likely in MSM reporting a known HIV-infected partner as infection source or symptoms compatible with acute retroviral syndrome. 'Region of birth' interacted with 'educational level' and 'steady partner as infection source': only African and Latin-American MSM with low educational level were more likely to present late; Latin-American men attributing their infection to steady partner, but no other MSM, had LP more frequently. In Spain, HIV testing among MSM should be promoted, especially those > 34 years old and migrants with low educational level. The current recommendation that MSM be tested at least once a year is appropriate.


Assuntos
Diagnóstico Tardio , Infecções por HIV/diagnóstico , Homossexualidade Masculina , Adulto , África/etnologia , Idade de Início , Centros Comunitários de Saúde , Aconselhamento , Escolaridade , Infecções por HIV/etnologia , Infecções por HIV/transmissão , Humanos , América Latina/etnologia , Masculino , Pessoa de Meia-Idade , Parceiros Sexuais , Infecções Sexualmente Transmissíveis/diagnóstico , Espanha/epidemiologia
13.
Dalton Trans ; 44(7): 3159-75, 2015 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-25579134

RESUMO

The focus of this paper is on the analysis of the structural and electronic order-disorder effects at long, medium and short ranges of titanium dioxide (TiO2) nanoparticles synthesized by the sol-gel process followed by the microwave-assisted solvothermal (MAS) method at low temperatures and short reaction times. X-ray diffraction (XRD), Rietveld refinement, micro-Raman (MR) spectroscopy, transmission electron microscopy (TEM) and X-ray spectroscopy (EDX) were used to characterize the TiO2 nanoparticles. Optical properties were investigated by ultraviolet-visible (UV-vis) and photoluminescence (PL) measurements performed at room temperature. XRD and Rietveld refinement confirmed the presence of the anatase and brookite phases; nonetheless anatase is the major phase. The X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of only Ti(4+) but the nonstoichiometry revealed that TiO2 NPs contain defects assigned to oxygen vacancies that lead to structural and electronic order-disorder effects observed by band gap narrowing and PL wide band emission. These intermediary energy levels (shallow and deep levels) created within the band gap act as acceptors/donors of electrons and recombination centers. The oxygen vacancies (VO(x), VO˙ and VO˙˙) responsible by degree of structural order-disorder are related to distortions (tilts) on the [TiO6] octahedron and changes in the bond lengths and bond angles between oxygen and titanium atoms that gave rise to new species of cluster makers such as [TiO6]', [TiO5·VO(x)], [TiO5·VO˙] and [TiO5·VO˙˙]. This structural transformation is consistent with a redistribution of electron density from highly ordered [TiO6](x) clusters which form distorted [TiO6]' as well as complex [TiO5·VO(x)], [TiO5·VO˙] and [TiO5·VO˙˙] clusters assigned to oxygen vacancies which were understood as displacements in the oxygen atoms' position in the bond lengths (Ti-O).

14.
Phys Chem Chem Phys ; 16(37): 20127-37, 2014 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-25133930

RESUMO

The influence of tetrabutylammonium hydroxide on the phase composition (cubic zinc blende versus hexagonal wurtzite) of ZnS nanoparticles was studied. The ZnS nanoparticles were prepared by a microwave-assisted solvothermal method, and the phase structure and optical properties along with the growth process of ZnS nanoparticles were studied. We report XRD, FE-SEM, EDXS, UV-vis and PL measurements, and first-principles calculations based on TDDFT methods in order to investigate the structural and electronic properties and the growth mechanism of ZnS nanostructures. The effects as well as the merits of microwave heating on the process and characteristics of the obtained ZnS nanostructures and their performance are reported.

15.
Arq. bras. med. vet. zootec ; 66(4): 1023-1032, 08/2014. tab, graf
Artigo em Português | LILACS | ID: lil-722562

RESUMO

A avaliação radiográfica do casco é essencial no diagnóstico e na avaliação da laminite em equinos, contudo poucos estudos têm sido feitos em raças nacionais. O objetivo deste trabalho foi realizar a morfometria de imagens radiográficas obtidas do dígito de éguas Mangalarga Marchador (MM), a fim de obter um perfil de medidas indicadoras de laminite nessa população e comparar grupos sem (escore corporal 5 e 6) e com (escore corporal 7 e 8) sinais de sobrepeso. Não houve diferença significativa entre os valores para as medidas dos dois grupos (P>0,05), mas verificou-se correlação positiva entre a distância entre os planos da linha coronária e do ápice do processo extensor (afundamento da falange distal) e indicadores de deposição de gordura localizada no pescoço e na base da cauda. Os achados demonstram que a morfometria radiográfica do dígito dessa população de equinos Mangalarga Marchador difere da de raças estrangeiras. Além disso, nos animais estudados, éguas com escore corporal 7 e 8 não aparentaram estarem mais sujeitas à laminite, uma vez que não houve diferença entre a morfometria de éguas com escore inferior. Entretanto, as correlações positivas entre índices de obesidade e a distância de afundamento da falange distal indicam que éguas Mangalarga Marchador também estão sujeitas à ocorrência de laminite associada à obesidade...


The radiographic evaluation of the hoof is essential in the diagnosis and follow-up of equine laminitis; however, few studies have been conducted in Brazilian breeds. The aim was to perform the morphometry of radiographic images taken from the digit of Mangalarga Marchador in order to obtain a profile of measurements indicative of laminitis in this population. We also compared measurements form mares without (body score 5 and 6) and with (body score 7 and 8) signs of overweight. There was no significant difference between measurements from the two groups (P> 0.05), but there was significant positive correlation between founder distance and signs of adiposity in the neck and in the base of the tail. Findings from this study demonstrate that radiographic morphology of the hoof from this population of Mangalarga Marchador mares differ from standard international reference values. Furthermore, in this group of mares, those with body condition grading 7 and 8 did not seem to be more prone to develop laminitis, since there was no difference when they were compared with mares showing lower grades. However, a significant correlation among founder distance and signs of adiposity in the neck and base of tail indicate that Mangalarga Marchador mares are also prone to obesity-associated laminitis...


Assuntos
Animais , Feminino , Biometria , Casco e Garras/patologia , Cavalos , Radiografia/veterinária , Sobrepeso/complicações , Doenças dos Cavalos/patologia , Obesidade/veterinária , Especificidade da Espécie
16.
J Nanosci Nanotechnol ; 14(9): 6662-8, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25924314

RESUMO

This paper reports both the controlled synthesis of Sn3O4 nanobelts by carbothermal reduction method and the gas sensor properties of these nanostructures. The synthesized material was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and gas sensor measurements. The results showed that the Sn3O4 nanobelts grow in a layered way and the careful control of experimental parameters is fundamental for stabilization of the correct phase. From the gas sensor measurements using oxygen as analyte gas, it was observed that the Sn3O4 nanobelts exhibit n-type behavior and both the sensitivity and the response time are dependent on the oxygen concentration. A model based on molecules adsorption was proposed to illustrate the mechanism of gas detection of these nanostructures. In summary, these results indicate that Sn3O4 nanobelts synthesized by carbothermal reduction method are promising to be applied as gas sensors.


Assuntos
Nanoestruturas/química , Nanotecnologia/métodos , Compostos de Estanho/química , Carbono/química , Oxigênio/análise
17.
Sci Rep ; 3: 1676, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23591807

RESUMO

In this letter, we report, for the first time, the real-time in situ nucleation and growth of Ag filaments on α-Ag2WO4 crystals driven by an accelerated electron beam from an electronic microscope under high vacuum. We employed several techniques to characterise the material in depth. By using these techniques combined with first-principles modelling based on density functional theory, a mechanism for the Ag filament formation followed by a subsequent growth process from the nano- to micro-scale was proposed. In general, we have shown that an accelerated electron beam from an electronic microscope under high vacuum enables in situ visualisation of Ag filaments with subnanometer resolution and offers great potential for addressing many fundamental issues in materials science, chemistry, physics and other fields of science.


Assuntos
Cristalização/métodos , Nanopartículas/química , Nanopartículas/ultraestrutura , Óxidos/química , Prata/química , Tungstênio/química , Elétrons , Nanopartículas/efeitos da radiação , Óxidos/efeitos da radiação , Tamanho da Partícula , Prata/efeitos da radiação , Resultado do Tratamento , Tungstênio/efeitos da radiação
18.
Int J Cosmet Sci ; 35(6): 539-45, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23614335

RESUMO

OBJECTIVES: In this research, an experimental and theoretical study was conducted to design a photodegradation mechanism of the amino acid tryptophan (Trp) in hair fibres. METHODS: For the experimental research, Caucasian hair fibres were exposed to several different solar radiation simulation periods. Then, Trp and its photoproducts (N-formylkynurenine and kynurenine) were assayed by excitation and emission spectroscopic analysis. RESULTS: For the theoretical study, reactions involved in the photodegradation of Trp were evaluated by high-level quantum mechanical calculations in a density functional theory (DFT) framework which indicate a probable Trp degradation mechanism with a minimum expended energy pathway. CONCLUSION: The biochemistry concerning these reactions is essentially important for a biological system where the degradation of Trp occurs.


Assuntos
Cabelo/química , Cabelo/efeitos da radiação , Triptofano/química , Raios Ultravioleta/efeitos adversos , Humanos , Cinurenina/análogos & derivados , Cinurenina/análise , Simulação de Dinâmica Molecular , Espectrometria de Fluorescência
19.
ACS Appl Mater Interfaces ; 3(2): 500-4, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21244018

RESUMO

Highly aligned CaCu(3)Ti(4)O(12) nanorod arrays were grown on Si/SiO(2)/Ti/Pt substrates by radio-frequency sputtering at a low deposition temperature of 300 °C and room temperature. Structural and morphological studies have shown that the nanostructures have a polycrystalline nature and are oriented perpendicular to the substrate. The high density of grain boundaries in the nanorods is responsible for the nonlinear current behavior observed in these arrays. The current-voltage (I-V) characteristics observed in nanorods were attributed to the resistive memory phenomenon. The electrical resistance of microcapacitors composed of CaCu(3)Ti(4)O(12) nanorods could be reversibly switched between two stable resistance states by varying the applied electric field. In order to explain this switching mechanism, a model based on the increase/decrease of electrical conduction controlled by grain boundary polarization has been proposed.

20.
Euro Surveill ; 14(48)2009 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-20003899

RESUMO

In Spain, neither the HIV nor the STI national surveillance systems collect information on HIV/STI co-infection. However, there are two networks based on HIV/STI clinics which gather this data. We describe HIV prevalence in men who have sex with men (MSM) diagnosed with infectious syphilis and/or gonorrhoea in 15 STI clinics; and concurrent diagnoses of STI in MSM newly diagnosed with HIV in 19 HIV/STI clinics. In total, 572 MSM were diagnosed with infectious syphilis and 580 with gonorrhoea during 2005-2007. HIV prevalence among syphilis and gonorrhoea cases was 29.8% and 15.2% respectively. In the multivariate analysis, HIV/syphilis co-infection was associated with being Latin American; having a history of STI; reporting exclusively anal intercourse; and having sex with casual or several types of partners. HIV and gonorrhoea co-infection was associated with age older than 45 years; having no education or only primary education completed; and having a history of STI. In total, 1,462 HIV infections were newly diagnosed among MSM during 2003-2007. Of these, 31.0% were diagnosed with other STI at the same time. Factors associated with STI co-infection among new HIV cases in MSM were being Latin American; and having sex with casual partners or with both steady and casual partners. In Spain, a considerable proportion of MSM are co-infected with HIV and STI.


Assuntos
Surtos de Doenças/estatística & dados numéricos , Infecções por HIV/epidemiologia , Homossexualidade Masculina/estatística & dados numéricos , Adulto , Humanos , Incidência , Masculino , Vigilância da População , Medição de Risco , Fatores de Risco , Espanha/epidemiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...