Quantum Dot in Z-shaped Graphene Nanoribbon

Stimulated by recent advances in isolating graphene, we discovered that quantum dot can be trapped in Z-shaped graphene nanoribbon junciton. The topological structure of the junction can confine electronic states completely. By varying junction length, we can alter the spatial confinement and the number of discrete levels within the junction. In addition, quantum dot can be realized regardless of substrate induced static disorder or irregular edges of the junction. This device can be used to easily design quantum dot devices. This platform can also be used to design zero-dimensional functional nanoscale electronic devices using graphene ribbons.Comment: 4 pages, 3 figure

A Simple Internal Resistance Estimation Method Based on Open Circuit Voltage Test under Different Temperature Conditions

© 2018 IEEE. State-of-charge (SoC) is one critical parameter for battery management system. SoC cannot be directly measured but it can be estimated according to some information of battery management system such as voltage and current. Two commonly used methods to estimate the SoC are 1) by using current times a constant internal resistance, and 2) by referring to a SoC-resistance lookup table to interface with an open-circuit-voltage (OCV)-SoC lookup table. However, these widely used testing methods of internal resistance have not considered the influence of SoC, temperature and current rate. which are in fact related to internal resistance. Therefore, ignoring the temperature and current rate factors will obtain inaccurate internal resistance measurement and battery SoC estimation. This paper hence proposes a dynamic resistance model with improved accuracy through combining SoC-OCV at different ambient temperatures with different discharging rates defined at the standard ambient temperature (25 degree) condition. The proposed method will not only improve the accuracy but also reduce the testing time

Tropical forest restoration: Fast resilience of plant biomass contrasts with slow recovery of stable soil C stocks

Due to intensifying human disturbance, over half of the world's tropical forests are reforested or afforested secondary forests or plantations. Understanding the resilience of carbon (C) stocks in these forests, and estimating the extent to which they can provide equivalent carbon (C) sequestration and stabilization to the old growth forest they replace, is critical for the global C balance. In this study, we combined estimates of biomass C stocks with a detailed assessment of soil C pools in bare land, Eucalyptus plantation, secondary forest and natural old-growth forest after over 50 years of forest restoration in a degraded tropical region of South China. We used isotope studies, density fractionation and physical fractionation to determine the age and stability of soil C pools at different soil depths. After 52 years, the secondary forests had equivalent biomass C stocks to natural forest, whereas soil C stocks were still much higher in natural forest (97.42 t/ha) than in secondary forest (58.75 t/ha) or Eucalyptus plantation (38.99 t/ha) and lowest in bare land (19.9 t/ha). Analysis of δ13C values revealed that most of the C in the soil surface horizons in the secondary forest was new C, with a limited increase of more recalcitrant old C, and limited accumulation of C in deeper soil horizons. However, occlusion of C in microaggregates in the surface soil layer was similar across forested sites, which suggests that there is great potential for additional soil C sequestration and stabilization in the secondary forest and Eucalyptus plantation. Collectively, our results demonstrate that reforestation on degraded tropical land can restore biomass C and surface soil C stocks within a few decades, but much longer recovery times are needed to restore recalcitrant C pools and C stocks at depth. Repeated harvesting and disturbance in rotation plantations had a substantial negative impact on the recovery of soil C stocks. We suggest that current calculations of soil C in secondary tropical forests (e.g. IPCC Guidelines for National Greenhouse Gas Inventories) could overestimate soil C sequestration and stabilization levels in secondary forests and plantations

Development of a composite regional vulnerability index and its relationship with the impacts of the COVID‑19 pandemic

The interactions between vulnerability and human activities have largely been regarded in terms of the level of risk they pose, both internally and externally, for certain groups of disadvantaged individuals and regions/areas. However, to date, very few studies have attempted to develop a comprehensive composite regional vulnerability index, in relation to travel, housing, and social deprivation, which can be used to measure vulnerability at an aggregated level in the social sciences. Therefore, this research aims to develop a composite regional vulnerability index with which to examine the combined issues of travel, housing and socio-economic vulnerability (THASV index). It also explores the index’s relationship with the impacts of the COVID-19 pandemic, reflecting both social and spatial inequality, using Greater London as a case study, with data analysed at the level of Middle Layer Super Output Areas (MSOAs). The findings show that most of the areas with high levels of composite vulnerability are distributed in Outer London, particularly in suburban areas. In addition, it is also found that there is a spatial correlation between the THASV index and the risk of COVID-19 deaths, which further exacerbates the potential implications of social deprivation and spatial inequality. Moreover, the results of the multiscale geographically weighted regression (MGWR) show that the travel and socio-economic indicators in a neighbouring district and the related vulnerability indices are strongly associated with the risk of dying from COVID-19. In terms of policy implications, the findings can be used to inform sustainable city planning and urban development strategies designed to resolve urban socio-spatial inequalities and the potential related impacts of COVID-19, as well as guiding future policy evaluation of urban structural patterns in relation to vulnerable areas

Cloning and characterization of small RNAs from wheat (Triticum aestivum L.)

Trabalho final do 6º ano médico com vista à atribuição do grau de mestre (área científica de gastroenterologia), apresentado à Faculdade de Medicina da Universidade de CoimbraIntrodução: A endoscopia digestiva tem sido fundamental para o diagnóstico e tratamento de muitas patologias do foro gastrenterológico. Contudo, todos os procedimentos endoscópicos acarretam algumas complicações. Estas são bastante baixas com a endoscopia diagnóstica, aumentando com a endoscopia terapêutica. Esta revisão apresenta uma introdução à incidência e prevenção das complicações que podem ocorrer após a endoscopia digestiva alta, colonoscopia e colangiopancreatografia endoscópica retrógrada. Métodos: A pesquisa bibliográfica foi efectuada através da b-on (pubmed, medline, …) utilizando as palavras-chave: complicações da endoscopia digestiva alta, complicações da colonoscopia, complicações da colangiopancreatografia retrógrada endoscópica. Resultados: As complicações pré-procedimento incluem as resultantes da sedação, da anestesia tópica e da preparação intestinal. As principais complicações processuais consistem, principalmente, em perfuração e hemorragia. Há também um risco de transmissão de doenças infecciosas de e para o paciente. Conclusões: A endoscopia, como todos os procedimentos invasivos, traz significativos riscos potenciais para o paciente. Contudo, endoscopistas experientes e sensibilizados para as potenciais complicações, utilizando material apropriado, nas devidas condições de utilização e instalações físicas adequadas, podem evitar e tratar atempadamente as complicações resultantes da endoscopia.Background: Endoscopy has been critical to the diagnosis and treatment of many gastroenterologic pathologies. However, all endoscopic procedures entail some complications. These are very low with diagnostic endoscopy, increasing with the therapeutic endoscopy. This review presents an introduction to the incidence and prevention of complications that may occur after upper endoscopy, colonoscopy and ERCP. Methods: The literature search was carried out by b-on (pubmed, medline,…) using the keywords: complications of endoscopy, complications of colonoscopy and complications of endoscopic retrograde cholangiopancreatography. Results: The pre-procedure complications include those arising from sedation, topical anesthesia and bowel preparation. The major procedural complications consist mainly of perforation and hemorrhage. There is also a risk of transmission of infectious diseases to and for the patient. Conclusions: Endoscopy, like all invasive procedures, carries significant potential risks to the patient. However, endoscopists experienced and aware of potential complications, using appropriate material, under appropriate conditions of use and adequate physical facilities, can prevent and treat complications in a timely manner