Elastocaloric Effect in Graphene Kirigami

Kirigami, a traditional Japanese art of paper-cutting, has recently been explored for its elastocaloric effect (ECE) in kirigami-based materials (KMs), where applying strain induces temperature changes. In this study, we investigate the ECE in a nanoscale graphene kirigami (GK) monolayer, representing the thinnest possible KM, to better understand this phenomenon. Through molecular dynamics simulations, we analyze the temperature change and coefficient of performance (COP) of the nanoscale GK architecture. Our findings reveal that while GKs lack the intricate temperature changes observed in macroscopic KMs, they exhibit a substantial temperature change of approximately 9.32 K (23 times higher than that of macroscopic KMs, which is about 0.4K) for heating and -3.50 K for cooling. Additionally, they demonstrate reasonable COP values of approximately 1.57 and 0.62, respectively. It is noteworthy that the one-atom-thick graphene configuration prevents the occurrence of the complex temperature distribution observed in macroscopic KMs.Comment: 14 pages, 06 figures, and 01 tabl

Abordagem dos pedículos glissonianos no manejo do trauma hepático

AIM:  To investigate a different approach in liver trauma, that preserves as much  liver parenchyma aspossible, exposing only the injured area to ischemia and reperfusion. MATHERIAL AND METHODS:Medline and pubMed search from 1980 to 2010 about the glissonian approach , including, liver, surgery,trauma, portal vein and hepatic artery as key-words .RESULTS: The glissonian approach is feasible, nottechnically demanding, and the key for the success is the knowledge of the anatomical landmarks  in theliver surface, to facilitate the surgeon to obtain a fast control of the injured area without compromising theliver flow to the non traumatic area.  CONCLUSION: The glissonian approach represents another toolthat can be performed in liver trauma setting to minimize complications related to the non-anatomicalremoval of parenchyma and blinded-ligaturesOBJETIVO: Investigar uma abordagem diferente no manejo do trauma hepático, que consiga preservaro máximo possível o parênquima do órgão, expondo apenas a área lesada à isquemia e posteriorreperfusão. METODOLOGIA: Pesquisa de artigos publicados nas bases de dados MedLine e pubMedno período de 1980 a 2010, sobre a abordagem dos pedículos glissonianos, e usando como palavrasde busca: fígado, cirurgia, trauma, veia porta e artéria hepática. RESULTADOS: A abordagem dos pedículosglissonianos é viável, não demanda de técnica cirúrgica elaborada, e a chave para o sucesso é ter umconhecimento anatômico do órgão, incluindo pontos importantes em sua superfície para que o cirurgião consiga obter o controle rápido de toda a área lesada sem comprometer o fluxo sanguíneo para asáreas sadias.  CONCLUSÃO: A abordagem glissoniana representa uma ferramenta que pode ser utilizada com segurança no cenário de um trauma hepático, para minimizar as complicações relacionadasa ressecção não anatômica do parênquima e ligaduras realizadas às cegas

Simulação de experimentos históricos no ensino de física: uma abordagem computacional das dimensões histórica e empírica da ciência na sala de aula

Neste trabalho propomos a utilização de simulações computacionais de experimentos históricos no ensino de física como estratégia de resgate e articulação das dimensões histórica e empírica da física na sala de aula. Como exemplo, apresentamos uma classe de simulação computacional didática, caracterizada aqui como Simulação Didática Interativa (SDI), utilizando o software Modellus para apresentar a experiência do plano inclinado proposta por Galileu Galilei(1564-1642) em sua obra Discursos e Demonstrações Matemáticas em Torno de Duas Novas Ciências (1638), onde a lei da queda dos corpos é investigada.</jats:p

Sun-Graphyne: A New 2D Carbon Allotrope with Dirac Cones

Due to the success achieved by graphene, several 2D carbon-based allotropes were theoretically predicted and experimentally synthesized. Here, we propose a new 2D carbon allotrope named Sun-Graphyne (S-GY). We used density functional theory and reactive molecular dynamics simulations to investigate its mechanical, structural, electronic, and optical properties. The results showed that S-GY exhibits good dynamical and thermal stabilities. Its formation energy and elastic moduli are -8.57 eV/atom and 262.37 GPa, respectively. S-GY is a semi-metal and presents two Dirac cones in its band structure. This material is transparent, and its intense optical activity is limited to the infrared region. Remarkably, the band structure of S-GY remains practically unchanged at even moderate strain regimes. As far as we know, this is the first 2D carbon allotrope to exhibit this behaviour.Comment: 17 pages, and 11 figure

Exploring the Elastic Properties and Fracture Patterns of Me-Graphene Monolayers and Nanotubes through Reactive Molecular Dynamics Simulations

Me-graphene (MeG) is a novel two-dimensional (2D) carbon allotrope. Due to its attractive electronic and structural properties, it is important to study the mechanical behavior of MeG in its monolayer and nanotube topologies. In this work, we conducted fully atomistic reactive molecular dynamics simulations using the Tersoff force field to investigate their mechanical properties and fracture patterns. Our results indicate that Young's modulus of MeG monolayers is about 414 GPa and in the range of 421-483 GPa for the nanotubes investigated here. MeG monolayers and MeGNTs directly undergo from elastic to complete fracture under critical strain without a plastic regime.Comment: 10 pages, 01 table, and 05 figure

Neutrinos Angra experiment: commissioning and first operational measurements

The Neutrinos Angra Experiment has completed a major step by finishing the comissioning of the detector and the data acquisition system at the experimental site located in the Angra dos Reis nuclear power plant. The experiment consists of a water-based detector and associated electronics, both designed with the goal of detecting the electron antineutrinos produced by the nuclear reactor. The detection is possible due to the Inverse Beta Decay, where the final products in the water are photons in the UV-to-visible range of the spectrum. The assembled detector comprises three active volumes filled with water: (i) a cubic target detector for electron antineutrinos, covered by 32 8-inches PMTs, (ii) a lateral layer surrounding the target (veto) equipped with 4 PMTs and (iii) a third volume covering the top of both, also equipped with 4~PMTs. In the present document the main features of the detector assembly as well as the integration of the readout electronics on-site are reported. Finally, some operational characteristics are shown based on straightforward analysis of the first measurements performed during the last months with the fully working detector