Formation of Atomic Carbon Chains from Graphene Nanoribbons

The formation of one-dimensional carbon chains from graphene nanoribbons is investigated using it ab initio molecular dynamics. We show under what conditions it is possible to obtain a linear atomic chain via pulling of the graphene nanoribbons. The presence of dimers composed of two-coordinated carbon atoms at the edge of the ribbons is necessary for the formation of the linear chains, otherwise there is simply the full rupture of the structure. The presence of Stone-Wales defects close to these dimers may lead to the formation of longer chains. The local atomic configuration of the suspended atoms indicates the formation of single and triple bonds, which is a characteristic of polyynes.Comment: 4 pages, 5 figure

Acessos de mandioca açucarada coletados no Nordeste paraense possuem o mesmo genótipo detectado por marcadores microssatélites.

A mandioca é encontrada na região Norte do Brasil e é usada como fonte de subsistência para muitas famílias. A mandioca açucarada ou mandiocaba, é um tipo de mandioca que armazena em suas raízes, além do amido, açúcares livres como reservas. Atualmente, vêm recebendo destaque pelo seu potencial para uso na fabricação de álcool combustível, devido ao acúmulo de glicose que pode ser convertida em etanol diretamente. Foi realizado teste para avaliar a diversidade genética de acessos de mandiocas açucaradas coletadas em diferentes locais do estado do Pará mantidos no banco de germoplasma da Embrapa Amazônia Oriental. Foi realizada a genotipagem molecular de nove acessos de mandioca açucarada e um acesso de mandioca brava com marcadores microssatélites. Para isso, foram utilizados 13 primers microssatélites e a corrida dos produtos amplificados foi realizada em géis de poliacrilamida 6%. Após a análise dos géis, foi verificado que todas as nove amostras de mandioca açucarada possuíam o mesmo genótipo, sendo verificada baixa variabilidade genética para esse grupo de mandiocas

Differential Responses of Yield and Shoot Traits of Five Tropical Grasses to N and Distance to Trees in Silvopastoral Systems

Light intensity and nitrogen (N) availability are important factors influencing the growth of C4 forage species. Trade-offs may occur in the adaptive responses of species to shading and N inputs, and functional shoot traits can help to explain the consequences of these responses for species performance. Our objective was to gain understanding of the mechanisms between traits of five C4 perennial grasses determining above-ground dry matter yield (DMY) when both resources, light and N, vary. Forage grasses were grown in six shading conditions (full sunlight vs. five positions between Eucalyptus dunnii rows) with two N levels (0 vs. 300 kg N ha-1year-1) and clipped when the canopy reached 95% light interception. Path analysis was used to explore the relationship between DMY, shading levels, N nutrition index and shoot traits. Dry matter yield increased between 126 to 569 g dry matter m-2 with N fertilization. Nitrogen nutrition index was the most important predictor for determining DMY followed by shading level. Increased shading reduced DMY by 9.5 g DM m- ² for each 1% of increase in shading. DMY was also modulated by shoot traits such as specific leaf area and leaf area index, but with different responses according to species, highlighting different strategies to cope with changes in light and N availability

Item response theory analysis of the recoded Internet Gaming Disorder Scale-Short-Form (IGDS9-SF)

Based on the nine criteria for Internet gaming disorder (IGD) in DSM-5, the Internet Gaming Disorder Scale 9-Short Form (IGDS9-SF; Pontes and Griffiths 2015) is the most widely used questionnaire for assessing IGD. The present study examined support for the unidimensional factor structure of the instrument, with a group of 868 adolescent and adult gamers from the USA, with criteria recoded as present or absent. The two-parameter logistic model (2PLM) was used to examine the item response theory properties of the criteria included in the measure. Confirmatory factor analysis supported the one-factor model. The 2PLM analysis indicated that all the criteria were strong discriminators of high and low latent IGD. Furthermore, the items measured more of the GAD dimension and with more precision from around +2 SD from the mean trait level. The implications of the findings for interpreting the IGDS9-SF scores for clinical practice are discussed

Assessment of the Italian version of the Internet Disorder Scale (IDS-15)

Much research has focused on the validation of psychometric tools assessing Internet addiction. One of the newest measures is the Internet Disorder Scale (IDS-15) based on the modified IGD criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). This study aimed at investigating the psychometric properties of the Italian version of the IDS-15 by examining the construct and the concurrent and the criterion-related validity and by identifying the taxonomy and the patterns of Internet users. A sample of 471 participants (Mage = 24.72 years, SD = 8.66; 256 males) was recruited from secondary schools, universities, and gaming halls. Confirmatory factor analyses supported the four-dimensional second-order structure and the three levels of the measurement invariance across gender. The reliability and the validity of the scale were confirmed, and the LPAs provided four classes of Internet users on the basis of the scores obtained in all four dimensions of the scale. The psychometric robustness of the Italian version of the IDS-15 was clearly demonstrated. Cross-cultural research should expand and generalize the present findings

Linfangioleiomiomatose pulmonar inicial provável e linfangioleiomioma mediastinal

A 68 year old woman was submitted to a mediastinal lymphangioleiomyoma resection found in a follow-up study of lower left lung resection due to bronchiectasis complicated by chylothorax. This led to a revaluation of the pulmonary specimen that revealed, in addition to inflammatory bronchiectasis, small spindle cell nodules in the lung parenchyma, similar to minute pulmonary meningothelial-like nodules, but with smooth muscle actin immunohistochemical positivity. The possibility of initial pulmonary development of lymphangioleiomyomatosis is discussed

A study on shrinkage and warpage of rotational moulded polyethylene

Warpage and poor dimensional stability of rotomoulded products are two of the main obstacles to the use of this technique in the production of engineering parts. The knowledge of the effect of the processing conditions on the shrinkage of rotomoulded parts will allow overcoming some of the restrictions of this process. In the present work the influence of the processing conditions on the development of shrinkage and warpage of rotomoulded parts was studied. The moulding of the parts was performed using a rotational moulding machine build at the University of Minho. The shrinkage and the warpage of the moulded parts were assessed using 3D MMC (3D measuring Machine Control) equipment, and understanding the microstructural development

Reduced Atlantic variability in the mid-Pliocene

This study evaluates interannual-to-decadal sea surface temperature (SST) variability in the mid-Pliocene Warm Period within the Pliocene Model Intercomparison Project (PlioMIP). Our results show significantly reduced variability at low latitudes and mid-latitudes in the mid-Pliocene in comparison to the pre-industrial climate. At high latitudes of both hemispheres, the SST variability has increased. Latitudinal changes are likely driven by changes in the meridional SST gradient. Results with respect to the main Atlantic SST modes of variability show that the Atlantic Multidecadal Variability shifts southward and expands eastward due to a southward shift in the North Atlantic Drift position. The Atlantic Meridional Mode amplitude weakens due to increased SST gradient between its two poles. The South Atlantic Subtropical Dipole significantly shifts its southwestern pole towards the South American coast. Moreover, all Atlantic modes of variability have shifted their respective frequencies towards lower values. Our analyses on the PlioMIP simulation results provide a useful constraint in future projections associated with a warmer world when assessing Atlantic SST variability

Procedimento de operação, manutenção e verificação de centrífuga JOUAN refrigerada.

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