Room temperature triplet state spectroscopy of organic semiconductors

Organic light-emitting devices and solar cells are devices that create, manipulate, and convert excited states in organic semiconductors. It is crucial to characterize these excited states, or excitons, to optimize device performance in applications like displays and solar energy harvesting. This is complicated if the excited state is a triplet because the electronic transition is ‘dark’ with a vanishing oscillator strength. As a consequence, triplet state spectroscopy must usually be performed at cryogenic temperatures to reduce competition from non-radiative rates. Here, we control non-radiative rates by engineering a solid-state host matrix containing the target molecule, allowing the observation of phosphorescence at room temperature and alleviating constraints of cryogenic experiments. We test these techniques on a wide range of materials with functionalities spanning multi-exciton generation (singlet exciton fission), organic light emitting device host materials, and thermally activated delayed fluorescence type emitters. Control of non-radiative modes in the matrix surrounding a target molecule may also have broader applications in light-emitting and photovoltaic devices.United States. Dept. of Energy. Center for Excitonics (Award DE-SC0001088

Analysis of Alzheimer's disease severity across brain regions by topological analysis of gene co-expression networks

<p>Abstract</p> <p>Background</p> <p>Alzheimer's disease (AD) is a progressive neurodegenerative disorder involving variations in the transcriptome of many genes. AD does not affect all brain regions simultaneously. Identifying the differences among the affected regions may shed more light onto the disease progression. We developed a novel method involving the differential topology of gene coexpression networks to understand the association among affected regions and disease severity.</p> <p>Methods</p> <p>We analysed microarray data of four regions - entorhinal cortex (EC), hippocampus (HIP), posterior cingulate cortex (PCC) and middle temporal gyrus (MTG) from AD affected and normal subjects. A coexpression network was built for each region and the topological overlap between them was examined. Genes with zero topological overlap between two region-specific networks were used to characterise the differences between the two regions.</p> <p>Results and conclusion</p> <p>Results indicate that MTG shows early AD pathology compared to the other regions. We postulate that if the MTG gets affected later in the disease, post-mortem analyses of individuals with end-stage AD will show signs of early AD in the MTG, while the EC, HIP and PCC will have severe pathology. Such knowledge is useful for data collection in clinical studies where sample selection is a limiting factor as well as highlighting the underlying biology of disease progression.</p

Padrões alimentares de adolescentes obesos e diferentes repercussões metabólicas Dietary patterns of obese adolescents and different metabolic effects

OBJETIVO: Avaliar a associação de padrões alimentares com alterações metabólicas em adolescentes obesos. MÉTODOS: Estudo transversal envolvendo 76 estudantes (ambos os sexos, 14-19 anos, IMC³P95 e Tanner ³4) de escolas públicas da cidade de São Paulo, Brasil. Foram coletados dados antropométricos e bioquímicos, e aplicados questionários com informações sociodemográficas e registro alimentar de 4 dias, entre 2006 e 2007. Escores fatoriais foram obtidos na análise fatorial e, após ajustes, três padrões alimentares identificados foram associados a fatores de risco biológico por regressão linear múltipla. RESULTADOS: O padrão Tradicional (arroz e massas, feijões, carnes vermelhas, embutidos, óleos e doces) foi positivamente associado com insulina, glicemia e triglicérides e negativamente associado com lipoproteína de alta densidade. O padrão Em Transição (peixe, aves, ovos, pães, manteiga, leite e derivados, hortaliças, frutas, sucos de frutas e açúcar refinado) apresentou as mesmas associações, além de associação similar com a pressão arterial diastólica. O padrão Fast Food (cafeteria, hambúrguer, maionese, bolacha, bolos e tortas, chocolate e refrigerantes) apresentou associação positiva com o colesterol, lipoproteína de baixa densidade e pressão arterial sistólica e diastólica, e associação negativa com insulina e lipoproteína de alta densidade. CONCLUSÃO: Os padrões Tradicional e Em transição apresentaram associações diferentes com o metabolismo lipídico e glicídico quando comparados com o padrão Fast Food. Os três padrões podem ser considerados obesogênicos, porém o padrão Fast Food pareceu ser o mais aterogênico e promotor de hipertensão arterial.<br>OBJECTIVE: This study assessed the association between dietary patterns and metabolic changes in obese adolescents. METHODS: This was a cross-sectional study of 76 students (both genders, 14-19 years old, BMI³P95 and Tanner stage ³4) enrolled in public schools from 2006 to 2007 in São Paulo city, Brazil. A sociodemographic questionnaire and 4-day food record were administered and anthropometric and biochemical data were collected. Scores for dietary patterns were assessed by factor analysis and after potential confounders were controlled, multilinear regression was used to associate the three identified patterns with biological risk factors. RESULTS: The Traditional Pattern (rice and cereals, beans, red meat, sausage, oils and sweets) was positively associated with insulin, blood glucose and triglycerides and negatively associated with high-density lipoprotein. The In-Transition pattern (fish, poultry, eggs, bread, butter, milk and dairy products, vegetables, fruits, fruit juice and white sugar), presented the same positive associations in addition to an association with diastolic blood pressure. The Fast Food pattern (high fat bakery products, hamburger, mayonnaise, cookies and crackers, chocolate and sodas) presented a positive association with cholesterol, low-density lipoprotein, systolic and diastolic blood pressure and a negative association with insulin and high-density lipoprotein. CONCLUSION: The Traditional and In-Transition patterns were differently related to glucose and lipid metabolism when compared with the fast food pattern. The three patterns could be considered obesogenic, however the Fast Food pattern seems to be the most atherogenic and promoter of hypertension