THE PHYSICS GRADUATE PROGRAM invites everyone to the seminar:
From Transistors to Switchable Memories: Development of Memristors for Data Processing
Miguel Henrique Boratto
Pós-doutorando – UFSC/FSC
Abstract:
The evolution of data-processing is dynamic and keeps changing the way we live nowadays. The device that immensely contributed for this advance, since the 1950s, is the transistor, the key of the evolution of electronic components. The great improvement of these devices has allowed the fabrication of small size and high-speed data-processing electronic equipment, such as the smartphones, million times faster than old computer machines. The commercial Random-Access Memory (RAM) is volatile, fabricated with a series of transistors and capacitors. A certain performance saturation has been achieved in these memories due to its volatile characteristic but also caused by the low performance of data transfer between the RAM and processing and storage units. A way to overcome such inertia is changing and exploring new architectures and materials such as the memristor, a non-volatile resistive switchable memory, that presents a simpler architecture with the necessary characteristics to substitute the transistor in data processing and storages [1,2]. The use of memristors may eliminate the use of three units (RAM, permanent storage, and processing) by doing all work simultaneously, avoiding the loss of processing speed caused by the transfer of data between units.
In this seminar, I will present a brief history of transistor and the differences between RAM and storage units. An emphasis will be given on the characteristics of memristors, as well as some state-of-the-art results obtained so far in the literature.
[1] M.H. Boratto, et al, Applied Surface Science, 410, 278-281, 2017. Doi: http://dx.doi.org/10.1016/j.apsusc.2017.03.132
[2] J.J.Yang et al, Nature Nanotechnology, 8, 13-24, 2013. Doi: 10.1038/NNANO.2012.240
Date: May 10, 2019 – (friday) – Place: Sala 212 – Auditório do Departamento de Física – Time: 10:15 a.m.
THE PHYSICS GRADUATE PROGRAM invites everyone to the seminar:
A New Experimental-3D Physical Modeling Approach Predicting Favorable Biomaterial-Cell Interactions
Rodney Marcelo do Nascimento
Pós-doutorando – UFSC/FSC
Abstract:
Despite several decades of research on biomedical implant materials, the identification of predictive and robust in vitro characteristics of cell support ability and viabilities—as indicators of biocompatibility and future implant-tissue integration—remain elusive. This study addresses the phenomenology of cell implant interfaces based on experimental, theoretical and numerical analysis of cell response to functionalized bioceramic coatings of commercial titanium implants, cp-Ti. A variable spectrum of coatings having differing surface wettabilities, with optimized solid tension values, was obtained. Measured values were modeled and correlated to cell support ability and viabilities. The contributions of different physico-chemical aspects to cell viability were decoupled resulting in the identification of the polar component of the surface free energy as a significant and major cell-substrate effector. Furthermore, our results and the suggested model establish the thermodynamic interfacial free energy as an omnipotent measure that can be fully correlated to the morphology of an individual cell under numerical simulation matching empirical observations. Collectively, the 3D physical modeling reported herein can offer a new generic theoretical framework, using implementable mathematical simulation, towards the objective of rational biomaterial design that can improve next generation metal and ceramic implants.
Date: May 3, 2019 – (friday) – Place: Sala 212 – Auditório do Departamento de Física – Time: 10:15 a.m.
THE PHYSICS GRADUATE PROGRAM invites everyone to the seminar:
VVV-WIT-07: outra estrela da Tabby ou um objeto de Mamajek?
Roberto Kalbush Saito
UFSC/FSC
Abstract:
Muitas, se não a maioria das estrelas, apresentam variações temporais de brilho. O estudo dessas variações nos ajuda na compreensão da estrutura interna das estrelas e dependendo da escala de tempo e perfil dessas variações estas são classificadas dentro das diversas classes de estrelas variáveis existentes.
VVV-(What Is This?)-07 é uma estrela variável única recentemente descoberta entre as quase 1 bilhão de estrelas observadas pelo projeto VISTA Variables in the Vía Láctea (VVV) na região central da Galáxia. A VVV-WIT-07 apresenta uma sequência recorrente porém não periódica de perdas de brilho ao longo dos anos 2010-2018, com um possível eclipse profundo em julho de 2012 quando o brilho do objeto diminuiu em cerca 80%, o que não é esperado para uma estrela.
As variações de brilho de VVV-WIT-07 são similares àquelas vistas na estrela J1407 (o objeto de Mamajek), onde acredita-se que uma estrela pré-sequência principal é eclipsada por um planeta com anéis muito maiores e densos que os de Saturno ou, alternativamente, à estrela KIC 8462852 (a estrela de Tabby), onde as variações de brilho poderiam estar associadas à presença de anéis irregulares de poeira, planetesimais, ou mesmo uma nuvem de cometas ao redor da estrela.
Neste seminário apresentaremos nossa análise de VVV-WIT-07 baseada em dados do projeto VVV e VVV eXtended (VVVX), e complementada com dados de arquivo e observações espectroscópicas de seguimento. Cenários alternativos, nenhum dos quais totalmente consistente com os dados disponíveis, também serão apresentados.
Date: April 26, 2019 – (tuesday) – Place: Sala 212 – Auditório do Departamento de Física – Time: 10:15 a.m.
