Encapsulation of small magnetic clusters in fullerene cages: A density functional theory investigation within van der Waals corrections

The encapsulation of magnetic transition-metal (TM) clusters inside carbon cages (fullerenes, nanotubes) has been of great interest due to the wide range of applications, which spread from medical sensors in magnetic resonance imaging to photonic crystals. Several theoretical studies have been reported; however, our atomistic understanding of the physical properties of encapsulated magnetic TM 3d clusters is far from satisfactory. In this work, we will report general trends, derived from density functional theory within the generalized gradient approximation proposed by Perdew, Burke, and Ernzerhof (PBE), for the encapsulation properties of the TMm@C-n (TM = Fe, Co, Ni; m = 2-6, n = 60,70,80,90) systems. Furthermore, to understand the role of the van der Waals corrections to the physical properties, we employed the empirical Grimme's correction (PBE + D2). We found that both PBE and PBE + D2 functionals yield almost the same geometric parameters, magnetic and electronic properties, however, PBE + D2 strongly enhances the encapsulation energy. We found that the center of mass of the TMm clusters is displaced towards the inside C-n surfaces, except for large TMm clusters (m = 5 and 6). For few cases, e. g., Co-4 and Fe-4, the encapsulation changes the putative lowest-energy structure compared to the isolated TMm clusters. We identified few physical parameters that play an important role in the sign and magnitude of the encapsulation energy, namely, cluster size, fullerene equatorial diameter, shape, curvature of the inside C-n surface, number of TM atoms that bind directly to the inside C-n surface, and the van der Waals correction. The total magnetic moment of encapsulated TMm clusters decreases compared with the isolated TMm clusters, which is expected due to the hybridization of the d-p states, and strongly depends on the size and shape of the fullerene cages.

Synthesis and Solar Cell Application of New Alternating Donor-Acceptor Copolymers Based on Variable Units of Fluorene, Thiophene, and Phenylene

A new series of donor acceptor copolymers were synthesized via the Witting route and applied as an active layer in organic thin-films solar cells. These copolymers are composed of fluorene thiophene and phenylene thiophene units. The ratio between those was systematically varied, and copolymers containing 0%, 50%, and 75% of phenylene thiophene were characterized and evaluated when used in photovoltaic devices. The copolymers' composition, photophysical, electrical, and morphological properties are addressed and correlated with device performance. The 50% copolymer ratio was found to be the best copolymer of the series, yielding a power conversion efficiency (PCE) under air mass (AM) 1.5 conditions of 2.4% in the bilayer heterojunction with the C-60 molecule. Aiming at flexible electronics applications, solutions based on the heterojunction of this copolymer with PCBM (6,6-phenyl-C-61-butyric acid methyl ester) were also successfully deposited using an inkjet printing method and used as an active layer in solar cells.

Annotated record of the detailed examination of Mn deposits from THETA-1 (TH1) Expedition stations

The cores described in this list were taken on the THETA-1 (TH1) Expedition in June to September 1956 from the R/V Theta. A total of 19 cores and dredges were recovered and are archived at Scripps for sampling and study.

Physical parameters in relation to physiological changes of avocado during ripening (20ºc) and cold storage (6ºc) in different conditions.

The application of the response of fruits to low energy for mechanical impacts is described, for evaluation of post-harvest ripening of avocadoes of the variety "Hass". An impactor of 50g of weight, provided with an accelerometer, and free-falling from a height of 4 cm, is used; it is interfaced to a computer and uses a special software for retrieving and analyzing the deceleration data. Impact response parameters of individual fruits were compared to firmness of the pulp, measured by the most used method of double-plate puncture, as well as to other physical and physiological parameters: color, skin puncture ethylene production rate and others. Two groups of fruits were carefully selected, stored at 6º C (60 days) and ripened at 20ºC (11 days), and tested during the storage period. It is shown that, as in other types of fruits, impact response can be a good predictor of firmness in avocadoes, obtaining the same accuracy as with destructive firmness measurements. Mathematical and multiple regression models are calculated and compared to measured data, with which a prediction of storage period can be made for these fruits.

Custos de procedimentos de saúde e associação com nível de atividade física e estado nutricional de idosos hipertensos e diabéticos: análise do Estudo SABE - Saúde, Bem-estar e Envelhecimento, 2010

Introdução O nível de atividade física (NAF) insuficiente e estado nutricional (EN) inadequado conferem risco de desenvolvimento de hipertensão arterial e diabete, bem como dificultam o controle destas doenças. Assim, infere-se que os custos despendidos pelo SUS com medicamentos, internações e consultas de hipertensos e diabéticos apresentem relação inversa com NAF, incluindo a prática de caminhada e EN. Entretanto, estudos epidemiológicos que descrevam estes custos e analisem essas associações na população idosa são inexistentes no Brasil, o que dificulta a fundamentação para a implementação de políticas publicas para a economia de recursos. Objetivo Descrever os custos com procedimentos de saúde de idosos hipertensos e diabéticos e verificar qual a sua associação com NAF e EN, segundo sexo e grupos etários. Métodos A amostra foi constituída por 806 idosos com autorreferência à hipertensão e/ou diabete ( 60 anos) residentes no município de São PauloSP, participantes das três coortes do Estudo Saúde, Bem-estar e Envelhecimento SABE - em 2010. A variável dependente custo total anual (em Reais), foi estimada com base nos dados autorreferidos sobre uso de medicamentos, uso dos serviços ambulatoriais e internações hospitalares, retroativos a um ano da coleta de dados. A variáveis explanatórias: i) NAF foi estimada a partir de entrevista utilizando o International Physical Activity Questionnaire (IPAQ, versão curta), classificando os idosos segundo duração da realização de atividades físicas moderada, em ativos ( 150 minutos/semana) e insuficientemente ativos (< 150 minutos/semana); ii) Prática de caminhada, categorizada segundo frequência semanal: a) 4 dias/ semana; b) 1 a 3 dias/semana; c) não caminha. iii) EN, identificado pelo índice de massa corporal (IMC), classificando os idosos em dois grupos: a) IMC < 28 kg/ m²; b) IMC 28 kg/ m² (excesso de peso); as variáveis de controle foram o sexo, grupos etários (a. 70 anos; b. 65 a 69 anos; c. 60 a 64 anos); estado civil (a. casado; b. outros) e, escolaridade (a. sem escolaridade; b. 1 ano). A descrição dos custos segundo as NAF e EN foi representada pelos valores de média e IC95 por cento , mediana e P25 P75, valores mínimos e máximos. Modelos de regressão logística múltipla foram empregados para analisar as associações entre variáveis dependentes e explanatórias. O nível de significância foi estabelecido em 5 por cento e todas as análises foram realizadas considerando amostras complexas, por meio do software Stata, 13.0. 9 Resultados: A média de custo total anual por pessoa foi de R$ 732,54 e a soma dos custos relativa a 12 meses para os 806 idosos foi de R$ 609.587,20, sempre superiores para idosos em excesso de peso, com NAF insuficiente e para idosos que não caminham. Idosos em excesso de peso apresentaram chance 50 por cento superior de estarem no grupo de maior custo total anual (OR 1.49, IC95 por cento 1.01 2.18) e mais de 70 por cento superior de maior custo com medicamentos (OR 1.71, IC95 por cento 1.18 2.47). A ausência de caminhada significou a chance superior para maiores custos anuais com medicamentos (OR 1.63, IC95 por cento 1.06 2.51) e custos totais (OR 1.82, IC95 por cento 1.17 2.81). Todas as análises ajustadas por sexo e idade. O NAF não se associou aos custos totais e custo com medicamentos (p>0.05). Conclusão: Os custos para o controle de HAS e DM em idosos são altos e se associam inversamente à prática de caminhada e ao estado nutricional, especialmente em relação ao custo com o uso de medicamentos antihipertensivos e hipoglicemiantes.

Determinação de vitaminas antioxidantes em suplementos e avaliação da rotulagem nutricional

Introdução: Diante das mudanças nos hábitos de consumo alimentar da população brasileira, suplementos vitamínicos e alimentos enriquecidos são veículos comumente empregados para atender as necessidades de ingestão de micronutrientes. A diversidade de suplementos vitamínicos comercializados atualmente leva à necessidade de desenvolvimento de métodos analíticos de fácil execução e alta produtividade. Informações confiáveis sobre os teores de vitaminas poderão ser obtidas somente com métodos analíticos validados. Objetivos: Validar metodologias analíticas e avaliar o teor de vitaminas antioxidantes em suplementos adquiridos no comércio do município de São Paulo - Brasil, o efeito do armazenamento nestes compostos e confrontar os valores analisados com os valores declarados na rotulagem. Métodos: As metodologias analíticas para determinação de vitaminas antioxidantes por cromatografia líquida de alta eficiência com detector de arranjo de diodos (CLAE-DAD) e de vitamina C por titulação potenciométrica foram validadas para as matrizes sólidas, oleosas e líquidas de suplementos vitamínicos. A estabilidade das vitaminas foi avaliada a cada 6 meses durante 12 meses de armazenamento e a avaliação da rotulagem foi realizada de acordo com as legislações vigentes no Brasil. Resultados: Para os métodos cromatográficos, os limites de detecção (LDs) e de quantificação (LQs) variaram entre 0,3 e 4,3 µg/mL, e entre 0,5 e 14,0 µg/mL respectivamente. As recuperações dos padrões adicionados nas matrizes variaram entre 92 por cento e 109 por cento e entre 86 por cento e 108 por cento no material de referência. A repetitividade foi calculada pelo desvio padrão relativo (RSD), apresentando valores entre 0,2 por cento e 9,6 por cento . Para a determinação de vitamina C pelo método potenciométrico, o LD e o LQ foram respectivamente 1 mg e 3 mg; a recuperação no material de referência foi de 99,8 por cento e a precisão variou entre 0,4 e 3,9 por cento . Das 57 amostras avaliadas, 59 por cento e 35 por cento apresentaram teores de vitaminas A e E respectivamente, abaixo dos valores declarados no rótulo; por outro lado, 20 por cento das amostras apresentaram teores de vitamina E acima dos valores declarados. Em relação aos teores de vitamina C, 60 por cento das amostras estavam de acordo com os valores declarados. O estudo da estabilidade demonstrou degradação significativa das vitaminas A, E e C em aproximadamente 90 por cento das amostras com 12 meses de armazenamento. Na avaliação da rotulagem dos suplementos vitamínicos, 47 das amostras apresentaram uma ou mais irregularidades. Conclusão: Os métodos propostos se mostraram adequados para análise de diferentes matrizes de suplementos vitamínicos. Os resultados das análises de vitaminas nestes produtos mostraram a necessidade urgente de monitoramento em conjunto com ações de fiscalização, pois verificou-se que a maioria das amostras não atenderam a legislação, principalmente quanto aos teores declarados na informação nutricional da rotulagem. A sobredosagem de vitaminas pode ser necessária para manter os teores declarados durante o armazenamento, porém, a quantidade adicional de vitamina a ser incluída no suplemento deve estar dentro de limites seguros e depende de cada amostra, pois além da matriz, diversos fatores relacionados aos compostos e à embalagem também podem influenciar na estabilidade das vitaminas.

Impact of acute weight loss and/or thermal stress on rowing ergometer performance

Purpose: The impact of acute weight loss on rowing performance was assessed when generous nutrient intake was provided in 2 h of recovery after making weight. Methods: Competitive rowers (N = 17) completed four ergometer trials, each separated by 48 h. Two trials were performed after a 4% body mass loss in the previous 24 h (WT) and two were performed after no weight restrictions, that is, unrestricted (UNR). In addition, two trials (I X WT, I X UNR) were in a thermoneutral environment (NEUTRAL, mean 21.1 +/- SD 0.7 degrees C, 29.0 +/- 4.5% RH) and two were in the heat (HOT 32.4, +/- 0.4 degrees C, 60.4 +/- 2.7% RH). Trials were performed in a counterbalanced fashion according to a Latin square design. Aggressive nutritional recovery strategies (WT 2.3 g(.)kg(-11) carbohydrate, 34 mg-kg(-1) Na, 28.4 mL(.)kg(-1) fluid; UNR ad libitum) were employed in the 2 h after weigh-in. Results: Both WT (mean 2.1, 95% CI 0.7-3.4 s; P = 0.003) and HOT (4.1, 2.7 - 5.4 s; P < 0.001) compromised 2000-m time-trial performance. Whereas WT resulted in hypohydration, the associated reduction in plasma volume explained only part of the performance compromise observed (0.2 s for every 1% decrement) Moreover, WT did not influence core temperature or indices of cardiovascular function. Conclusions: Acute weight loss compromised performance, despite generous nutrient intake in recovery, although the effect was small. Performance decrements were further exacerbated when exercise was performed in the heat.

Van der Waals interactions between two parallel infinitely long single-walled nanotubes

The potential energies of van der Waals (VDW) interactions between two parallel, infinitely long and perfect SWNTs with identical, and different sizes were studied based on the continuum Lennard-Jones model. The conclusion of Girifalco's work on (n, n) SWNTs that the potentials of SWNT-SWNT fell on a single curve, is also applicable to SWNTs with different sizes. We further obtained the corresponding constants of the well depth phi(0) and equilibrium VDW gap g(0) for SWNTs with a radius from 2 to 25 Angstrom. (C) 2005 Elsevier B.V. All rights reserved.

Simple approach to estimating the van der Waals interaction between carbon nanotubes

The van der Waals (vdW) interactions between carbon nanotubes (CNTs) were studied based on the continuum Lennard-Jones model. It was found that all the vdW potentials between two arbitrary CNTs fall on the same curve when plotted in terms of certain reduced parameters, the well depth, and the equilibrium vdW gap. Based on this observation, an approximate approach is developed to obtain the vdW potential between two CNTs without time-consuming computations. The vdW potential estimated by this approach is close to that obtained from complex integrations. Therefore, the developed approach can greatly simplify the calculation of vdW interactions between CNTs.

Age and growth in olive ridley seaturtles (Lepidochelys olivacea) from the north-central Pacific: a skeletochronological analysis

The olive ridley is the most abundant seaturtle species in the world but little is known of the demography of this species. We used skeletochronological data on humerus diameter growth changes to estimate the age of North Pacific olive ridley seaturtles caught incidentally by pelagic longline fisheries operating near Hawaii and from dead turtles washed ashore on the main Hawaiian Islands. Two age estimation methods [ranking, correction factor (CF)] were used and yielded age estimates ranging from 5 to 38 and 7 to 24 years, respectively. Rank age-estimates are highly correlated (r = 0.93) with straight carapace length (SCL), CF age estimates are not (r = 0.62). We consider the CF age-estimates as biologically more plausible because of the disassociation of age and size. Using the CF age-estimates, we then estimate the median age at sexual maturity to be around 13 years old (mean carapace size c. 60 cm SCL) and found that somatic growth was negligible by 15 years of age. The expected age-specific growth rate function derived using numerical differentiation suggests at least one juvenile growth spurt at about 10–12 years of age when maximum age-specific growth rates, c. 5 cm SCL year−1, are apparent.

Spin-detection in a quantum electromechanical shuttle system

We study the electrical transport of a harmonically bound, single-molecule C-60 shuttle operating in the Coulomb blockade regime, i.e. single electron shuttling. In particular, we examine the dependance of the tunnel current on an ultra-small stationary force exerted on the shuttle. As an example, we consider the force exerted on an endohedral N@C-60 by the magnetic field gradient generated by a nearby nanomagnet. We derive a Hamiltonian for the full shuttle system which includes the metallic contacts, the spatially dependent tunnel couplings to the shuttle, the electronic and motional degrees of freedom of the shuttle itself and a coupling of the shuttle's motion to a phonon bath. We analyse the resulting quantum master equation and find that, due to the exponential dependence of the tunnel probability on the shuttle-contact separation, the current is highly sensitive to very small forces. In particular, we predict that the spin state of the endohedral electrons of N@C-60 in a large magnetic gradient field can be distinguished from the resulting current signals within a few tens of nanoseconds. This effect could prove useful for the detection of the endohedral spin-state of individual paramagnetic molecules such as N@C-60 and P@C-60, or the detection of very small static forces acting on a C-60 shuttle.

Experimental studies of hypothallus growth in the lichen Rhizocarpon geographicum

Removal of the areolae of the crustose lichen Rhizocarpon geographicum (L.)DC. resulted in either low or no measurable radial growth of the marginal hypothallus. Radial growth of the hypothallus was also significantly reduced compared with intact thalli when (1) areolae were removed to within 1 and 2 mm of the hypothallus and (2) a 5 mm wide ‘moat’ was created between the areolae and the hypothallus. Adding ribitol (0.01 M) to isolated hypothalli at 3-month intervals over 15 months results in total radial growth c. 60% that of intact thalli. Adding an arabitol/mannitol mixture (0.05 M arabitol, 0.03 M mannitol) increased radial growth compared with deionized water and ribitol treatments. Adding ribitol (0.7 M), arabitol (0.2 M) and mannitol (0.08 M) to the areolae of intact thalli had no significant effects on radial growth of the hypothallus. On a south-facing rock surface, isolated hypothalli grew at a similar rate to intact thalli for 2 months. Growth then declined and the hypothalli disappeared from the rock surface within 6 months. The effects of addition of carbohydrate suggest that the marginal hypothallus has the capacity to utilize exogeneous materials. However, in intact thalli in the field, the radial growth of the hypothallus is likely to be a result of transfer of materials from the areolae through hyphal connections.

Catalytic supercritical water gasification of plastics with supported RuO2:a potential solution to hydrocarbons-water pollution problem

Here we report on a potential catalytic process for efficient clean-up of plastic pollution in waters, such as the Great Pacific Garbage Patch (CPGP). Detailed catalytic mechanisms of RuO2 during supercritical water gasification of common polyolefin plastics including low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP) and polystyrene (PP), have been investigated in a batch reactor at 450 °C, 60 min. All four plastics gave very high carbon gasification efficiencies (CGE) and hydrogen gasification efficiencies (HGE). Methane was the highest gas component, with a yield of up to 37 mol kg−1LDPE using the 20 wt% RuO2 catalyst. Evaluation of the gas yields, CGE and HGE revealed that the conversion of PS involved thermal degradation, steam reforming and methanation; whereas hydrogenolysis was a possible additional mechanism during the conversion of aliphatic plastics. The process has the benefits of producing a clean-pressurized methane-rich fuel gas as well as cleaning up hydrocarbons-polluted waters.

Estudo de um compósito Nb-15%pCu obtidos por moagem de alta energia e sinterizados por fase líquida

There is great difficulty in forming a composite refractory metal niobium with copper. This is due to the fact that Nb-Cu system is almost mutually immiscible and may be neglected solubility between them. These properties hinder or prevent obtaining homogeneous and high-density structures, conventionally prepared. This study aims to analyze the use of high-energy milling process (MAE) to implement these natural difficulties, with regard to the densification of the sintered bodies. The MAE and the press were used in the preparation of powders, to obtain a fine and homogeneous distribution of the grain size. Four loads Nb and Cu powders containing 15% by weight of Cu were then milled for MAE in a planetary type ball mill under various milling times and speeds. The results obtained by MAE were analyzed by scanning electron microscopy (SEM), according to the parameters of time and grinding speed. The samples were compacted under pressure of 200 MPa, were then sintered in liquid phase in a vacuum furnace at temperatures of 1100 ° C / 60 min and 1200 ° C / 60 min. Then it was used to characterize diffraction of X-rays to identify the phases. The microstructures of the sintered samples were observed and evaluated using scanning electron microscopy (SEM). Vickers Microhardness tests were performed, obtaining higher values for the sintered bodies in the largest of the post milling times and the larger grinding speeds. It was found that the liquid phase sintering of the samples that were processed by MAE produced at the end of a homogeneous and densified structure in 77,4% relative to the value of the theoretical density of the composite

Influência dos ácidos graxos do tipo ômega-3 ou ômega-6 e o nanomaterial de carbono fulereno (C60) no estado antioxidante em suspensões celulares de cérebro de Cyprinus carpio (Pisces, Cyprinidae)

Os nanomateriais de carbono como o fulereno (C60) apresenta comportamentos bioquímicos distintos, podendo atuar como antioxidante ou pró-oxidante em diferentes sistemas biológicos. Outra evidência ao C60 refere-se a sua característica lipofilica, na qual oferece ação mais direta a diferentes tipos de membranas celulares. Do mesmo modo ácidos graxos poliinsaturados (AGPs) como o ômega-3 (DHA) e o ômega-6 (LA) são importantes para funções celulares da membrana, sendo considerados antioxidantes clássicos. Dessa forma este estudo avaliou em suspensões celulares de cérebro da carpa (Cyprinus carpio, Cyprinidae), o efeito de C60 após um pré-tratamento com DHA ou LA. Para tal avaliação os ensaios consistiram em um pré-tratamento com AGPs (48h) e após exposição a C60 (2h). Como resultados observamos que a viabilidade celular e a capacidade antioxidante total não apresentaram diferença (p> 0.05) entre todos os grupos. Em relação a valores de espécies ativas de oxigênio e dano lipídico foi observado redução nos seus valores nos grupos expostos ao C60 pré – tratados com AGPs (p<0.05). Em termos de cisteína, ocorre uma redução da sua concentração em todos os grupos expostos ao C60. Porém para glutationa a exposição ao C60 provoca um aumento de sua concentração nos grupo controle (sem AGPs) e no grupo pré – tratado com DHA. Dessa forma consideramos que o pré – tratamento com AGPs é benéfico às células, uma vez que um aumento nos níveis de glutationa e uma diminuição na concentração de espécies ativas de oxigênio e peroxidação lipídica foram observados nos grupos expostos ao C60. Sendo assim um bom estado nutritivo em termos da concentração de AGPs foi considerado benéfico na exposição ao fulereno.