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1.
Artigo em Inglês | MEDLINE | ID: mdl-38864317

RESUMO

BACKGROUND: Population-based studies have observed sex biases in the diagnosis and treatment of attention-deficit hyperactivity disorder (ADHD). Females are less likely to be diagnosed or prescribed ADHD medication. This study uses national healthcare records, to investigate sex differences in diagnosis and clinical care in young people with ADHD, particularly regarding recognition and treatment of other mental health conditions. METHODS: The cohort included individuals diagnosed with ADHD, born between 1989 and 2013 and living in Wales between 2000 and 2019. Routine primary and secondary healthcare record data were used to derive diagnoses of ADHD and other neurodevelopmental and mental health conditions, as well as ADHD and antidepressant medications. Demographic variables included ethnicity, socioeconomic deprivation and contact with social services. RESULTS: There were 16,458 individuals diagnosed with ADHD (20.3% females, ages 3-30 years), with a male-to-female ratio of 3.9:1. Higher ratios (4.8:1) were seen in individuals diagnosed younger (<12 years), with the lowest ratio (1.9:1) in those diagnosed as adults (>18). Males were younger at first recorded ADHD diagnosis (mean = 10.9 vs. 12.6 years), more likely to be prescribed ADHD medication and younger at diagnosis of co-occurring neurodevelopmental conditions. In contrast, females were more likely to receive a diagnosis of anxiety, depression or another mental health condition and to be prescribed antidepressant medications, prior to ADHD diagnosis. These sex differences were largely stable across demographic groups. CONCLUSIONS: This study adds to the evidence base that females with ADHD are experiencing later recognition and treatment of ADHD. The results indicate that this may be partly because of diagnostic overshadowing from other mental health conditions, such as anxiety and depression, or initial misdiagnosis. Further research and dissemination of findings to the public are needed to improve awareness, timely diagnosis and treatment of ADHD in females.

2.
BJPsych Open ; 10(3): e108, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38725371

RESUMO

BACKGROUND: People under the care of mental health services are at increased risk of suicide. Existing studies are small in scale and lack comparisons. AIMS: To identify opportunities for suicide prevention and underpinning data enhancement in people with recent contact with mental health services. METHOD: This population-based study includes people who died by suicide in the year following a mental health services contact in Wales, 2001-2015 (cases), paired with similar patients who did not die by suicide (controls). We linked the National Confidential Inquiry into Suicide and Safety in Mental Health and the Suicide Information Database - Cymru with primary and secondary healthcare records. We present results of conditional logistic regression. RESULTS: We matched 1031 cases with 5155 controls. In the year before their death, 98.3% of cases were in contact with healthcare services, and 28.5% presented with self-harm. Cases had more emergency department contacts (odds ratio 2.4, 95% CI 2.1-2.7) and emergency hospital admissions (odds ratio 1.5, 95% CI 1.4-1.7), but fewer primary care contacts (odds ratio 0.7, 95% CI 0.6-0.9) and out-patient appointments (odds ratio 0.2, 95% CI 0.2-0.3) than controls. Odds ratios were larger in females than males for injury and poisoning (odds ratio: 3.3 (95% CI 2.5-4.5) v. 2.6 (95% CI 2.1-3.1)). CONCLUSIONS: We may be missing existing opportunities to intervene, particularly in emergency departments and hospital admissions with self-harm presentations and with unattributed self-harm, especially in females. Prevention efforts should focus on strengthening routine care contacts, responding to emergency contacts and better self-harm care. There are benefits to enhancing clinical audit systems with routinely collected data.

3.
Psychol Sport Exerc ; 73: 102658, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38723755

RESUMO

The notion of secure base explains how a child can grow and become independent through access to a significant other (i.e., parent) who is available, encouraging, and noninterfering. The purpose of the current study was to develop an understanding of parental secure base support within the context of youth sport in Sweden, with a specific focus on: (a) what parental behaviors constitute a secure base, and (b) how these behaviors differ across contexts (at home before and after sport, at practice and during competitions). An interpretive descriptive methodology (Thorne, 2016) was used. Interviews were conducted with 13 family triads (children aged 12-15 years) and 1 dyad living in Sweden. Analysis was conducted to illuminate associations, patterns, and relationships within the sample. Analysis led to the development of nine categories of parental behaviors that were perceived to underpin a secure base. Availability was seen to comprise physical presence and support provision, being responsive, and developing positive mental representations. Encouragement encompassed demonstrating that sport participation is valued, motivating to explore sporting endeavors, and reinforcing and rewarding persistence in sports. Interference was described as unrequested interference, requested interference, and intentionally constrained involvement. Additionally, influencing factors such as communication, family structure and culture, were identified. The findings provide an empirical illustration for several behaviors that have been perceived as positive in previous literature, as well as highlighting numerous further complexities, particularly as it relates to interference.


Assuntos
Relações Pais-Filho , Esportes Juvenis , Humanos , Suécia , Adolescente , Criança , Masculino , Feminino , Esportes Juvenis/psicologia , Pais/psicologia , Poder Familiar/psicologia , Apoio Social , Comunicação
4.
Crisis ; 2023 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-37904497

RESUMO

Background: There is little information about characteristics and long-term outcomes of individuals who self-harm during a suicide cluster. Aims: To compare characteristics of individuals who self-harmed during a suicide cluster in South Wales (∼10 deaths between December 2007 and March 2008) with others who self-harmed prior to the cluster and to evaluate 10-year self-harm and mortality outcomes. Method: Using records from the hospital serving the catchment area of the suicide cluster, enhanced by national routinely collected linked data, we created the following two groups: individuals who self-harmed (a) during the suicide cluster and (b) 1 year before. We compared individuals' characteristics and performed logistic regression to compute odds ratios of 10-year self-harm and mortality outcomes. Results: Individuals who self-harmed during the cluster were less likely to be hospitalized or have a mental health history than those who self-harmed prior to the cluster. No significant group differences were found for 10-year self-harm outcomes, but all-cause mortality was higher for males. Limitations: Sample size was small, and data were lacking on psychological and social proximity to individuals who died during the suicide cluster. Conclusion: Our findings highlight the importance of long-term healthcare follow-up of those who self-harm during a suicide cluster, particularly males.

5.
Phys Chem Chem Phys ; 25(39): 26417-26428, 2023 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-37522306

RESUMO

In this work, we focus on the understanding of the driving force behind the S1-T1 excited-state energy inversion (which would thus violate Hund's rule, making the S1 state lower in energy than the T1 state) of two non-benzenoid non-alternant hydrocarbons, composed of odd-membered rings. The molecules considered here have identical chemical composition but different atomic configuration in space. The delicate interplay between structural and electronic factors that might induce inversion and its energy extension, only by a few meV, is systematically investigated here by state-of-the-art calculations. Qualitative and quantitative accurate predictions are obtained employing post-HF methods, thanks to the balanced and careful inclusion of electron correlation effects. The obtained results might guide and rationalize new searches for molecules violating Hund's rule, concomitantly demonstrating the importance of key contributions from the theoretical method of choice.

6.
J Chem Phys ; 156(3): 034105, 2022 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-35065561

RESUMO

The energy difference (ΔEST) between the lowest singlet (S1) state and the triplet (T1) excited state of a set of azaphenalene compounds, which is theoretically and experimentally known to violate Hund's rule, giving rise to the inversion of the order of those states, is calculated here with a family of double-hybrid density functionals. That excited-state inversion is known to be very challenging to reproduce for time-dependent density functional theory employing common functionals, e.g., hybrid or range-separated expressions, but not for wavefunction methods due to the inclusion of higher-than-single excitations. Therefore, we explore here if the last developed family of density functional expressions (i.e., double-hybrid models) is able to provide not only the right excited-state energy order but also accurate ΔEST values, thanks to the approximate inclusion of double excitations within these models. We herein employ standard double-hybrid (B2-PLYP, PBE-QIDH, and PBE0-2), range-separated (ωB2-PLYP and RSX-QIDH), spin-scaled (SCS/SOS-B2PLYP21, SCS-PBE-QIDH, and SOS-PBE-QIDH), and range-separated spin-scaled (SCS/SOS-ωB2-PLYP, SCS-RSX-QIDH, and SOS-RSX-QIDH) expressions to systematically assess the influence of the ingredients entering into the formulation while concomitantly providing insights for their accuracy.

7.
Phys Chem Chem Phys ; 23(41): 24016-24028, 2021 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-34664570

RESUMO

The energy difference between singlet and triplet excitons, or ΔEST, is a key parameter for novel light-emission mechanisms (i.e., TADF or thermally activated delayed fluorescence) or other photoactivated processes. We have studied a set of conjugated molecules (peri-acenoacenes and their heteroatom-doped analogues) to observe the evolution of their excited-state properties upon increasing the system size with and without substitution with a pair of N atoms. Since these molecules exhibit a (ground-state) diradicaloid character, together with marked correlation effects influencing the excited-states formed, we have applied a variety of theoretical methods (FT-DFT, TD-DFT, SF-TD-DFT, CIS, CIS(D), SCS-CC2, SA-CASSCF, and SC-NEVPT2) to bracket the accuracy of the results while concomitantly providing insights into electronic structure. The results show how this chemical strategy (N-doping) largely modifies not only the excited-state energies but also the oscillator strengths and the ΔEST values, constituting versatile platforms for fine-tuned photophysical applications.

8.
J Sports Sci ; 39(13): 1537-1547, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33605193

RESUMO

The purpose of this study was to examine the association between young players' perception of mother's and father's responsiveness with their self-esteem, anxiety (i.e., worry), and thriving (i.e., positive affect, vitality, and life satisfaction). In total, 314 male British rugby players with a mean age of 16.23 years (SD = 0.26) completed the study in two phases: n = 124 (first dataset), and n = 192 (second dataset). Participants trained on average 3.14 times/week (SD = 0.94) and had been involved in rugby for an average of 8.21 years (SD = 2.89). Participants completed questionnaires measuring perceived parental responsiveness (PPR) for their mother and father, self-esteem, worry about sport performance, and thriving indicators (i.e., positive affect, vitality, and life satisfaction). The results consistently indicated that participants' perceptions of their mother's and father's responsiveness positively related to thriving, and negatively related to their worry about sport performance, mediated by their self-esteem. Overall, the study highlights the need for parents to be provided with insights into the value of being responsive to their child and being encouraged to regularly talk with their child regarding their needs and desires, and seeking to understand how their child perceives the support they currently receive.


Assuntos
Afeto , Ansiedade/psicologia , Desempenho Atlético/psicologia , Futebol Americano/psicologia , Relações Pais-Filho , Autoimagem , Adolescente , Humanos , Masculino , Inquéritos e Questionários
9.
J Phys Chem A ; 125(2): 513-522, 2021 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-33401898

RESUMO

The full harvesting of both singlet and triplet excitons can pave the way toward more efficient molecular light-emission mechanisms (i.e., TADF or thermally activated delayed fluorescence) beyond the spin statistics limit. This TADF mechanism benefits from low (but typically positive) singlet-triplet energy gaps or ΔEST. Recent research has suggested the possibility of inverting the order of the energy of lowest singlet and triplet excited states, thus opening new pathways to promote light emission without any energy barrier through triplet to singlet conversion, which is systematically investigated here by means of theoretical methods. To this end, we have selected a set of heteroatom-substituted triangle-shaped molecules (or triangulenes) for which ΔEST < 0 is predicted. We successfully rationalize the origin of that energy inversion and the reasons for which theoretical methods might produce qualitatively inconsistent predictions depending on how they treat n-tuple excitations (e.g., the large contribution of double excitations for all of the ground and excited states involved). Unfortunately, the time-dependent density functional theory method is unable to deal with the physical effects driving this behavior, which prompted us to use more sophisticated ab initio methods here such as SA-CASSCF, SC-NEVPT2, SCS-CC2, and SCS-ADC(2).

10.
Chemphyschem ; 22(6): 553-560, 2021 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-33325598

RESUMO

We have investigated the origin of the S1 -T1 energy levels inversion for heptazine, and other N-doped π-conjugated hydrocarbons, leading thus to an unusually negative singlet-triplet energy gap ( ΔEST<0 ). Since this inversion might rely on substantial doubly-excited configurations to the S1 and/or T1 wavefunctions, we have systematically applied multi-configurational SA-CASSCF and SC-NEVPT2 methods, SCS-corrected CC2 and ADC(2) approaches, and linear-response TD-DFT, to analyze if the latter method could also face this challenging issue. We have also extended the study to B-doped π-conjugated systems, to see the effect of chemical composition on the results. For all the systems studied, an intricate interplay between the singlet-triplet exchange interaction, the influence of doubly-excited configurations, and the impact of dynamic correlation effects, serves to explain the ΔEST<0 values found for most of the compounds, which is not predicted by TD-DFT.

11.
Nanoscale Adv ; 2(6): 2448-2461, 2020 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-36133367

RESUMO

Localized Surface Plasmon Resonance (LSPR) of noble metal nanoparticles has attracted a lot of attention in recent years as enhancer of the photocatalytic activity in the visible light domain. Rare are the experimental in situ studies, coupling structural and optical responses, but they are mandatory for a deep understanding of the mechanisms underlying LSPR. Herein we present an in situ investigation during the growth of gold nanoparticles (NPs) on TiO2(110) in the 2-6 nm size range. We probed the structural and morphological properties of the supported nanoparticles by performing GIXRD and GISAXS simultaneously with their optical response in p and s polarizations recorded by SDRS. The rutile surface state turns out to have a major effect on the Au NPs growth and on their plasmonic response, both in frequency and vibration modes. The roughening of the TiO2(110) surface weakens the interaction strength between the NPs and the substrate, favoring the growth of textured in-plane randomly orientated NPs. Compared to the epitaxial clusters growing on the flat TiO2 surface, these textured NPs are characterized by a LSPR blue shift and by the presence of LSPR vibration modes perpendicular to the surface for sizes smaller than about 4 nm.

12.
APL Bioeng ; 3(4): 046103, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31803860

RESUMO

Enhanced vascular permeability in the lungs can lead to pulmonary edema, impaired gas exchange, and ultimately respiratory failure. While oxygen delivery, mechanical ventilation, and pressure-reducing medications help alleviate these symptoms, they do not treat the underlying disease. Mechanical activation of transient receptor potential vanilloid 4 (TRPV4) ion channels contributes to the development of pulmonary vascular disease, and overexpression of the high homology (HH) domain of the TRPV4-associated transmembrane protein CD98 has been shown to inhibit this pathway. Here, we describe the development of an adeno-associated virus (AAV) vector encoding the CD98 HH domain in which the AAV serotypes and promoters have been optimized for efficient and specific delivery to pulmonary cells. AAV-mediated gene delivery of the CD98 HH domain inhibited TRPV4 mechanotransduction in a specific manner and protected against pulmonary vascular leakage in a human lung Alveolus-on-a-Chip model. As AAV has been used clinically to deliver other gene therapies, these data raise the possibility of using this type of targeted approach to develop mechanotherapeutics that target the TRPV4 pathway for treatment of pulmonary edema in the future.

13.
Nat Nanotechnol ; 14(12): 1143-1149, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31712665

RESUMO

Affinity-based electrochemical detection in complex biological fluids could enable multiplexed point-of-care diagnostics for home healthcare; however, commercialization of point-of-care devices has been limited by the rapid loss of sensitivity caused by electrode surface inactivation and biofouling. Here, we describe a simple and robust antifouling coating for electrodes consisting of a three-dimensional porous matrix of cross-linked bovine serum albumin supported by a network of conductive nanomaterials composed of either gold nanowires, gold nanoparticles or carbon nanotubes. These nanocomposites prevent non-specific interactions while enhancing electron transfer to the electrode surface, preserving 88% of the original signal after 1 month of exposure to unprocessed human plasma, and functionalization with specific antibodies enables quantification of anti-interleukin 6 in plasma with high sensitivity. The easy preparation, stability and simplicity of this nanocomposite allow the generation of electrochemical biosensors that can operate in complex biological fluids such as blood plasma or serum.


Assuntos
Técnicas Biossensoriais/instrumentação , Ouro/química , Nanopartículas Metálicas/química , Nanotubos de Carbono/química , Soroalbumina Bovina/química , Anticorpos/sangue , Incrustação Biológica , Técnicas Eletroquímicas/instrumentação , Eletrodos , Desenho de Equipamento , Humanos , Proteínas Imobilizadas/química , Modelos Moleculares , Nanotubos de Carbono/ultraestrutura , Plasma/química
14.
J Bone Joint Surg Am ; 101(7): 635-649, 2019 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-30946198

RESUMO

BACKGROUND: Chronic periprosthetic joint infection (PJI) is a devastating complication that can occur following total joint replacement. Patients with chronic PJI report a substantially lower quality of life and face a higher risk of short-term mortality. Establishing a diagnosis of chronic PJI is challenging because of conflicting guidelines, numerous tests, and limited evidence. Delays in diagnosing PJI are associated with poorer outcomes and morbid revision surgery. The purpose of this systematic review was to compare the diagnostic accuracy of serum, synovial, and tissue-based tests for chronic PJI. METHODS: This review adheres to the Cochrane Collaboration's diagnostic test accuracy methods for evidence searching and syntheses. A detailed search of MEDLINE, Embase, the Cochrane Library, and the grey literature was performed to identify studies involving the diagnosis of chronic PJI in patients with hip or knee replacement. Eligible studies were assessed for quality and bias using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Meta-analyses were performed on tests with sufficient data points. Summary estimates and hierarchical summary receiver operating characteristic (HSROC) curves were obtained using a bivariate model. RESULTS: A total of 12,616 citations were identified, and 203 studies met the inclusion criteria. Of these 203 studies, 170 had a high risk of bias. Eighty-three unique PJI diagnostic tests were identified, and 17 underwent meta-analyses. Laboratory-based synovial alpha-defensin tests and leukocyte esterase reagent (LER) strips (2+) had the best performance, followed by white blood-cell (WBC) count, measurement of synovial C-reactive protein (CRP) level, measurement of the polymorphonuclear neutrophil percentage (PMN%), and the alpha-defensin lateral flow test kit (Youden index ranging from 0.78 to 0.94). Tissue-based tests and 3 serum tests (measurement of interleukin-6 [IL-6] level, CRP level, and erythrocyte sedimentation rate [ESR]) had a Youden index between 0.61 to 0.75 but exhibited poorer performance compared with the synovial tests mentioned above. CONCLUSIONS: The quality of the literature pertaining to chronic PJI diagnostic tests is heterogeneous, and the studies are at a high risk for bias. We believe that greater transparency and more complete reporting in studies of diagnostic test results should be mandated by peer-reviewed journals. The available literature suggests that several synovial fluid-based tests perform well for diagnosing chronic PJI and their use is recommended in the work-up of any suspected case of chronic PJI. LEVEL OF EVIDENCE: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.


Assuntos
Artroplastia de Quadril/efeitos adversos , Artroplastia do Joelho/efeitos adversos , Infecções Relacionadas à Prótese/diagnóstico , Infecções Relacionadas à Prótese/metabolismo , Doença Crônica , Testes Hematológicos , Técnicas Histológicas , Humanos , Infecções Relacionadas à Prótese/etiologia , Líquido Sinovial/metabolismo
15.
Lab Chip ; 19(3): 452-463, 2019 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-30632575

RESUMO

Here, we describe methods for combining impedance spectroscopy measurements with electrical simulation to reveal transepithelial barrier function and tissue structure of human intestinal epithelium cultured inside an organ-on-chip microfluidic culture device. When performing impedance spectroscopy measurements, electrical simulation enabled normalization of cell layer resistance of epithelium cultured statically in a gut-on-a-chip, which enabled determination of transepithelial electrical resistance (TEER) values that can be compared across device platforms. During culture under dynamic flow, the formation of intestinal villi was accompanied by characteristic changes in impedance spectra both measured experimentally and verified with simulation, and we demonstrate that changes in cell layer capacitance may serve as measures of villi differentiation. This method for combining impedance spectroscopy with simulation can be adapted to better monitor cell layer characteristics within any organ-on-chip in vitro and to enable direct quantitative TEER comparisons between organ-on-chip platforms which should help to advance research on organ function.


Assuntos
Espectroscopia Dielétrica/instrumentação , Mucosa Intestinal/citologia , Dispositivos Lab-On-A-Chip , Células CACO-2 , Estimulação Elétrica , Desenho de Equipamento , Humanos , Mucosa Intestinal/metabolismo
16.
J Phys Chem Lett ; 9(20): 6149-6163, 2018 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-30265539

RESUMO

Thermally activated delayed fluorescence (TADF) offers promise for all-organic light-emitting diodes with quantum efficiencies competing with those of transition-metal-based phosphorescent devices. While computational efforts have so far largely focused on gas-phase calculations of singlet and triplet excitation energies, the design of TADF materials requires multiple methodological developments targeting among others a quantitative description of electronic excitation energetics, fully accounting for environmental electrostatics and molecular conformational effects, the accurate assessment of the quantum mechanical interactions that trigger the elementary electronic processes involved in TADF, and a robust picture for the dynamics of these fundamental processes. In this Perspective, we describe some recent progress along those lines and highlight the main challenges ahead for modeling, which we hope will be useful to the whole TADF community.

17.
J Arthroplasty ; 33(7): 2159-2164.e1, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29506929

RESUMO

BACKGROUND: Outpatient total knee arthroplasty (TKA) has been made possible with advances in perioperative care and standardized clinical inpatient pathways. While many studies report on benefits of outpatient programs, none explore patient-reported outcome measures. As such, our goals were to compare the short-term quality of recovery; highlight postdischarge hospital resources utilization; and report on 2-year functional outcomes scores. METHODS: This was a prospective comparative cohort study of 43 inpatients (43 TKAs) and 43 outpatients (43 TKAs) operated on by a single surgeon between September 28, 2010 and May 5, 2015. All patients were given a diary to complete at 1, 3, 7, 14, and 28 days postoperatively; we collected 90-day complications, readmissions, and emergency department visits; Knee Injury and Osteoarthritis Outcome Score and Western Ontario and McMaster Universities Osteoarthritis Index scores were completed preoperatively and 2 years postoperatively. SPSS (IBM, version 22.0) was used for all statistical analyses. RESULTS: Quality of recovery (QoR-9) was similar in the outpatient TKA group compared with the inpatient group. No statistically significant differences were observed for Knee Injury and Osteoarthritis Outcome Score and Western Ontario and McMaster Universities Osteoarthritis Index subscores (P > .05). There was 1 readmission in both outpatient and inpatient groups. Six inpatients and 8 outpatients returned to the emergency department for any reason within 90 days, with no statistical significance observed between the 2 groups (P = .771). CONCLUSION: Outpatient TKA in selected patients produced similar short-term and 2-year patient-reported outcome measures and a comparable 90-day postdischarge hospital resource utilization when compared to an inpatient cohort, supporting further investigation into outpatient TKA.


Assuntos
Artroplastia do Joelho/efeitos adversos , Artroplastia do Joelho/psicologia , Osteoartrite do Joelho/cirurgia , Pacientes Ambulatoriais , Medidas de Resultados Relatados pelo Paciente , Idoso , Feminino , Humanos , Pacientes Internados , Masculino , Pessoa de Meia-Idade , Alta do Paciente , Readmissão do Paciente , Período Pós-Operatório , Estudos Prospectivos , Índice de Gravidade de Doença , Fatores de Tempo , Resultado do Tratamento
18.
Nat Commun ; 9(1): 954, 2018 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-29507287

RESUMO

Singlet fission, the spin-allowed photophysical process converting an excited singlet state into two triplet states, has attracted significant attention for device applications. Research so far has focused mainly on the understanding of singlet fission in pure materials, yet blends offer the promise of a controlled tuning of intermolecular interactions, impacting singlet fission efficiencies. Here we report a study of singlet fission in mixtures of pentacene with weakly interacting spacer molecules. Comparison of experimentally determined stationary optical properties and theoretical calculations indicates a reduction of charge-transfer interactions between pentacene molecules with increasing spacer molecule fraction. Theory predicts that the reduced interactions slow down singlet fission in these blends, but surprisingly we find that singlet fission occurs on a timescale comparable to that in pure crystalline pentacene. We explain the observed robustness of singlet fission in such mixed films by a mechanism of exciton diffusion to hot spots with closer intermolecular spacings.

19.
Lab Chip ; 17(13): 2294-2302, 2017 06 27.
Artigo em Inglês | MEDLINE | ID: mdl-28608907

RESUMO

Here we demonstrate that microfluidic cell culture devices, known as Organs-on-a-Chips can be fabricated with multifunctional, real-time, sensing capabilities by integrating both multi-electrode arrays (MEAs) and electrodes for transepithelial electrical resistance (TEER) measurements into the chips during their fabrication. To prove proof-of-concept, simultaneous measurements of cellular electrical activity and tissue barrier function were carried out in a dual channel, endothelialized, heart-on-a-chip device containing human cardiomyocytes and a channel-separating porous membrane covered with a primary human endothelial cell monolayer. These studies confirmed that the TEER-MEA chip can be used to simultaneously detect dynamic alterations of vascular permeability and cardiac function in the same chip when challenged with the inflammatory stimulus tumor necrosis factor alpha (TNF-α) or the cardiac targeting drug isoproterenol. Thus, this Organ Chip with integrated sensing capability may prove useful for real-time assessment of biological functions, as well as response to therapeutics.


Assuntos
Técnicas de Cultura de Células/instrumentação , Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas/instrumentação , Linhagem Celular , Impedância Elétrica , Eletrodos , Desenho de Equipamento , Células Endoteliais da Veia Umbilical Humana , Humanos , Técnicas Analíticas Microfluídicas/métodos
20.
Lab Chip ; 17(13): 2264-2271, 2017 06 27.
Artigo em Inglês | MEDLINE | ID: mdl-28598479

RESUMO

Trans-epithelial electrical resistance (TEER) is broadly used as an experimental readout and a quality control assay for measuring the integrity of epithelial monolayers cultured under static conditions in vitro, however, there is no standard methodology for its application to microfluidic organ-on-a-chip (organ chip) cultures. Here, we describe a new microfluidic organ chip design that contains embedded electrodes, and we demonstrate its utility for assessing formation and disruption of barrier function both within a human lung airway chip lined by a fully differentiated mucociliary human airway epithelium and in a human gut chip lined by intestinal epithelial cells. These chips with integrated electrodes enable real-time, non-invasive monitoring of TEER and can be applied to measure barrier function in virtually any type of cultured cell.


Assuntos
Impedância Elétrica , Células Epiteliais , Dispositivos Lab-On-A-Chip , Modelos Biológicos , Técnicas de Cultura de Órgãos/instrumentação , Células Cultivadas , Células Epiteliais/citologia , Células Epiteliais/fisiologia , Epitélio/fisiologia , Desenho de Equipamento , Humanos
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