Hard Spheres: Crystallization and Glass Formation

Motivated by old experiments on colloidal suspensions, we report molecular dynamics simulations of assemblies of hard spheres, addressing crystallization and glass formation. The simulations cover wide ranges of polydispersity s (standard deviation of the particle size distribution divided by its mean) and particle concentration. No crystallization is observed for s > 0.07. For 0.02 < s < 0.07, we find that increasing the polydispersity at a given concentration slows down crystal nucleation. The main effect here is that polydispersity reduces the supersaturation since it tends to stabilise the fluid but to destabilise the crystal. At a given polydispersity (< 0.07) we find three regimes of nucleation: standard nucleation and growth at concentrations in and slightly above the coexistence region; "spinodal nucleation", where the free energy barrier to nucleation appears to be negligible, at intermediate concentrations; and, at the highest concentrations, a new mechanism, still to be fully understood, which only requires small re-arrangement of the particle positions. The cross-over between the second and third regimes occurs at a concentration, around 58% by volume, where the colloid experiments show a marked change in the nature of the crystals formed and the particle dynamics indicate an "ideal" glass transition

Transcriptional control of glyoxalase 1 by Nrf2 provides a stress-responsive defence against dicarbonyl glycation

Abnormal cellular accumulation of the dicarbonyl metabolite MG (methylglyoxal) occurs on exposure to high glucose concentrations, inflammation, cell aging and senescence. It is associated with increased MG-adduct content of protein and DNA linked to increased DNA strand breaks and mutagenesis, mitochondrial dysfunction and ROS (reactive oxygen species) formation and cell detachment from the extracellular matrix. MG-mediated damage is countered by glutathione-dependent metabolism by Glo1 (glyoxalase 1). It is not known, however, whether Glo1 has stress-responsive up-regulation to counter periods of high MG concentration or dicarbonyl stress. We identified a functional ARE (antioxidant-response element) in the 5'-untranslated region of exon 1 of the mammalian Glo1 gene. Transcription factor Nrf2 (nuclear factor-erythroid 2 p45 subunit-related factor 2) binds to this ARE, increasing basal and inducible expression of Glo1. Activators of Nrf2 induced increased Glo1 mRNA, protein and activity. Increased expression of Glo1 decreased cellular and extracellular concentrations of MG, MG-derived protein adducts, mutagenesis and cell detachment. Hepatic, brain, heart, kidney and lung Glo1 mRNA and protein were decreased in Nrf2-/- mice, and urinary excretion of MG protein and nucleotide adducts were increased approximately 2-fold. We conclude that dicarbonyl stress is countered by up-regulation of Glo1 in the Nrf2 stress-responsive system, protecting protein and DNA from increased damage and preserving cell function

Apolipoprotein E polymorphism distribution in an elderly Brazilian population: the Bambuí Health and Aging Study

Apolipoprotein E (ApoE) is one of the most extensively studied genes in the context of aging, but there are few population-based studies on ApoE polymorphism in the elderly in developing countries. The objective of the present study was to assess ApoE allele and genotype distribution in a large elderly community-based sample and its association with age, sex and skin color. Participants included 1408 subjects (80.8% of all residents aged ³60 years) residing in Bambuí city, MG, Brazil. The DNA samples were subjected to the polymerase chain reaction amplification, followed by the restriction fragment length polymorphism technique, with digestion by HhaI. Analysis was carried out taking into consideration the six ApoE genotypes (e3/e3, e3/e4, e2/e3, e4/e4, e2/e4, and e2/e2), the three ApoE alleles, and the number of ApoE4 alleles for each individual. The e3 allele predominated (80.0%), followed by e4 (13.5%) and e2 (6.5%). All six possible genotypes were observed, the e3/e3 genotype being the most frequent (63.4%). This distribution was similar to that described in other western populations. Sex was not associated with number of ApoE4 alleles. Black skin color was significantly and independently associated with the presence of two ApoE4 alleles (age-sex adjusted OR = 7.38; 95%CI = 1.93-28.25), showing that the African-Brazilian elderly have a high prevalence of the e4 allele, as observed in blacks from Africa. No association between number of ApoE4 alleles and age was found, suggesting the absence of association of ApoE genotype with mortality in this population

Electronic structure of periodic curved surfaces -- topological band structure

Electronic band structure for electrons bound on periodic minimal surfaces is differential-geometrically formulated and numerically calculated. We focus on minimal surfaces because they are not only mathematically elegant (with the surface characterized completely in terms of "navels") but represent the topology of real systems such as zeolites and negative-curvature fullerene. The band structure turns out to be primarily determined by the topology of the surface, i.e., how the wavefunction interferes on a multiply-connected surface, so that the bands are little affected by the way in which we confine the electrons on the surface (thin-slab limit or zero thickness from the outset). Another curiosity is that different minimal surfaces connected by the Bonnet transformation (such as Schwarz's P- and D-surfaces) possess one-to-one correspondence in their band energies at Brillouin zone boundaries.Comment: 6 pages, 8 figures, eps files will be sent on request to [email protected]

A definição dos idosos de qualidade de vida

OBJECTIVES: Senescence for some elderly people is a phase of with development and satisfaction, whereas for others is a negative stage of life. The determinants of a good quality of life in old age vary from person to person. The aims of this study were to identify: 1) the prevalence of octogenarian people who evaluate their current life as being mainly characterized by a positive quality and 2) which were the domains that they identified as being the determinants of this positive quality. A same parallel study was conducted with subjects who evaluated senescence as a preponderantly negative experience. METHODS: A random and representative sample of 35% of the octogenarian people, living residing in the community, was selected among the dwellers of the city of Veranópolis, state of Rio Grande do Sul. A semi-structured questionnaire on quality of life quality was applied as well as the scale of depressive symptoms Geriatric Depression Scale (GDS) and the index of general health Cumulative Illness Rating Scale (CIRS). RESULTS: Slightly more than half of the studied sample (57%) defined their current quality of life with positive evaluations, whereas 18% presented a negative evaluation of it. A group 0f 25% defined their current lives as neutral or having both values (positive and negative). Those who were dissatisfied presented more health problems according to the CIRS and more depressive symptoms when evaluated by the GDS. Satisfied subjects ones had different reasons to justify this state, however, the dissatisfied had mainly the lack of health as a reason for their suffering. The main source of reported daily well-being was the involvement with rural or domestic activities. Among the interviewed, lack of health was the main source for not presenting well-being, although there was interpersonal variability regarding what each subject considered as loss of health. CONCLUSION: Possibly, for the elderly subjects a negative quality of life is equivalent to loss of health and a positive life quality is equivalent to a greater range of categories such as activity, income, social life and relationship with the family, categories which differed from subject to subject. Therefore, health seems to be a good indicator of negative quality of life, though an insufficient indicator of successful elderliness.OBJETIVOS: A velhice para alguns é uma etapa de desenvolvimento e satisfação, enquanto para outros é uma fase negativa da vida. Os determinantes da boa qualidade de vida na velhice variam de sujeito para sujeito. O objetivo do presente estudo foi identificar: 1) a prevalência de octagenários que avaliavam sua vida atual na velhice como preponderantemente de uma qualidade positiva e 2) quais aspectos eles identificavam como os determinantes desta qualidade positiva. Igual estudo em paralelo foi feito com sujeitos que avaliavam a velhice como uma experiência preponderantemente negativa. MÉTODOS: Uma amostra randômica e representativa de 35% dos idosos com mais de 80 anos residentes na comunidade foi selecionada entre os residentes em Veranópolis, Rio Grande do Sul. Um questionário semi- estruturado de qualidade de vida foi aplicado, bem como a escala de sintomas depressivos Geriatric Depression Scale (GDS) e o Índice de Saúde Geral Cumulative Illness Rating Scale (CIRS). RESULTADO: Um pouco mais da metade dos idosos estudados (57%) definia sua qualidade de vida atual com avaliações positivas, sendo que 18% tinham uma avaliação negativa da vida atual. Um grupo de 25% definia sua vida atual de forma neutra ou de dois valores (aspectos positivos e aspectos negativos). Comparados com os satisfeitos, os insatisfeitos tinham mais problemas de saúde pela CIRS e mais sintomas depressivos quando avaliados pela GDS. Os satisfeitos tinham diferentes motivos para justificar este estado, porém os insatisfeitos tinham principalmente a falta de saúde física como motivo do sofrimento. A maior fonte de bem estar no dia-a-dia citada era o envolvimento com atividades rurais ou domésticas. Entre os entrevistados, a perda da saúde física era a principal fonte de mal estar, sendo que havia variabilidade interpessoal quanto ao que cada sujeito considerava como perda de saúde. CONCLUSÃO: É possível que para idosos, qualidade negativa de vida seja equivalente a perda de saúde e qualidade de vida positiva seja equivalente a uma pluralidade maior de categorias como atividade, renda, vida social e relação com a família, categorias diferentes de sujeito para sujeito. O aspecto saúde parece assim um bom indicador de qualidade de vida negativa, porém um indicador insuficiente de velhice bem sucedida.Catholic University of the state of Rio Grande do Sul Institute of Geriatrics and Gerontology Geriatric neuropsychiatric ambulatoryWHO PAHO Associated Chronic Degenerating DiseasesFederal University of São Paulo Paulista Medical School Department of PsychiatryPUCRS Medical School Department of PsychiatryUNIFESP, EPM, Department of PsychiatrySciEL

Life-cycle assessment of domestic and transboundary recycling of post-consumer PET bottles

Abstract Background, aim, and scope In recent years, besides being recycled domestically, a part of Japanese post-consumer polyethylene terephthalate (PET) bottles have been exported to and recycled in mainland China. In this study, life-cycle assessment (LCA) was applied to compare domestic and transboundary recycling scenarios between Japan and China and disposal scenarios from the viewpoints of greenhouse gases (GHG) emission and fossil resource consumption. Methods The following 10 scenarios based on our field surveys were evaluated: Japanese post-consumer PET bottles are (i) recycled into polyester staple in Japan, (ii) recycled into polyester filaments in Japan, (iii) recycled into polyester clothes in Japan, (iv) chemically decomposed and recycled into bottle-grade PET resin in Japan, (v) chemically decomposed and recycled into polyester filaments in Japan, (vi)-(vii) recycled into polyester staple via two different flows in China, (viii) recycled into polyester clothes in China, (ix) incinerated and partly recovered as electricity in Japan, and (x) directly landfilled in Japan. In all the evaluated scenarios, the functional unit is the recycling or disposal of 1 kg of Japanese post-consumer PET bottles. The system boundaries range from waste collection by municipalities to the manufacture of recycled products that can be regarded as substitutes for virgin products, and a credit for the avoided production of equivalent virgin products is given to each scenario. The inventories of both foreground and background processes in Japan were quoted from published reports and databases. The actual conditions of PET bottle recycling that were obtained through field surveys in China were reflected to some inventories of foreground processes in China. The inventories of public electricity supplies in China were based on the national statistics, and the inventories of petroleum products, industrial water supply, and waste treatment are based on our field surveys in China. Other unknown inventories in China were substituted by corresponding inventories in Japan. Results and discussion The results showed that all the domestic and transboundary recycling scenarios had smaller GHG emissions and fossil resource consumptions than the incineration scenario and that the chemical recycling scenarios had larger GHG emissions and fossil resource consumptions than the other recycling scenarios. The landfilling scenario had the largest fossil resource consumption, while it was better than the incineration scenario and slightly better than the chemical recycling scenarios from the viewpoint of GHG emission. The robustness of the results was examined, and it was found that the differences in GHG emission and fossil resource consumption between the domestic and transboundary recycling scenarios, other than the scenarios including cloth-manufacturing processes in system boundaries, were sufficiently large to be robust against the variability of background parameters for electricity supplies. As for the Responsible editor: Shabbir Gheewala Electronic supplementary material The online version of this articl

Molecular packing density of a self-assembled monolayer formed from N-(2-aminoethyl)-3-aminopropyltriethoxysilane by a vapor phase process.

The molecular density of an aminosilane self-assembled monolayer formed from N-(2-aminoethyl)-3-aminopropyltriethoxysilane (AEAPS) by a vapor phase method has been estimated to be about 3 AEAPS molecules per nm(2) based on chemical labeling, optical absorption spectroscopy and X-ray photoelectron spectroscopy

Generalized anxiety disorder in a population aged 80 years and older

OBJECTIVE: To describe the prevalence of generalized anxiety disorder (GAD) in a community-dwelling population aged 80 years and older. Also, to compare sleep patterns, cognitive function and prevalence rate of other psychiatric conditions between healthy controls and GAD subjects. METHODS: DSM-IV criteria were used to diagnose GAD. A representative random sample of 77 community-dwelling subjects (35%), aged 80 years or more from the rural southern county of Veranopolis, Brazil, was selected. Sleep patterns were assessed using the Pittsburgh Sleep Quality Index and a 2-week sleep/wake diary. Five neuropsychological tests (Buschke-Fuld Selective Reminding Test, CERAD word list, verbal fluency test, and two sub-tests of the Wechsler memory scale) were used for cognitive evaluation. RESULTS: The estimated GAD prevalence was 10.6 percent. GAD was associated with major depression, with a significant greater number of depressive symptoms as measured by the Geriatric Depression Scale and with a significant more frequent occurrence of minor depression. Sleeping patterns and cognition function among GAD subjects were not compromised. The severity of physical diseases was similar in both GAD subjects and healthy controls. GAD was associated with a significantly lower health-related quality of life. CONCLUSIONS: In comparison with previous studies, the prevalence of GAD is higher in the studied population. This disorder is frequently associated with both depressive symptoms and a lower health-related quality of life.OBJETIVOS: Descrever a prevalência de transtorno de ansiedade generalizada (TAG) em uma população de idosos residentes em uma comunidade e com idade acima de 80 anos e comparar os padrões de sono, a função cognitiva e a taxa de prevalência de outros diagnósticos psiquiátricos entre controles normais e sujeitos com TAG. MÉTODOS: Para o diagnóstico de TAG, foram utilizados os critérios do Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). Selecionou-se uma amostra randômica e representativa de 77 sujeitos (35%), residentes em uma comunidade, entre todos os idosos com idade acima de 80 anos do município Veranópolis, RS. Os padrões de sono foram aferidos pelo índice de qualidade de sono de Pittsburgh e pelo diário sobre sono/vigília a ser preenchido ao longo de duas semanas. Cinco testes neuropsicológicos foram usados na avaliação cognitiva: teste das lembranças seletivas de Buschke-Fuld; lista de palavras da bateria CERAD (Consortium to Establish a Registry for Alzheimer's Disease); teste de fluência verbal e dois subtestes da escala de memória Wechsler. RESULTADOS: A prevalência estimada de TAG foi de 10,6%, cuja presença estava associada a uma maior ocorrência de depressão clinicamente diagnosticável, com um significativo maior número de sintomas depressivos, quando medidos pela escala de depressão geriátrica, e com uma maior ocorrência de depressão menor. Os padrões de sono e o funcionamento cognitivo, entre sujeitos com TAG, não estavam afetados. A gravidade das doenças físicas não variava entre sujeitos com TAG e os controles normais. A presença de TAG estava associada a um significativo pior padrão de qualidade de vida relativa à saúde. CONCLUSÃO: Em comparação com os estudos prévios, a prevalência de TAG é alta entre a população de idosos mais velhos. Esse transtorno ocorre em freqüente associação com a sintomatologia depressiva e também está associado a um pior padrão de qualidade de vida relativa à saúde.Instituto de Geriatria e Gerontologia Associação de Neuropsicologia do IdosoUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina (UNIFESP/EPM) Departamento de PsiquiatriaUNIFESP-EPM Departamento de NeurologiaUNIFESP-EPM Departamento de PsicobiologiaUNIFESP, EPM, (UNIFESP/EPM) Depto. de PsiquiatriaUNIFESP, EPM Depto. de NeurologiaUNIFESP, EPM Depto. de PsicobiologiaSciEL