Category Archives: Seminars

Wednesday 3 October 2018 16:00 – 17:00 Seminar Room 1

“Defining canonical NF-κB regulated target genes involved in lung cancer to develop novel biomarkers and potential therapies”

Dr. Geogios Markopoulos Institute of Molecular Biology and Biotechnology (IMBB)

Abstract
Lung Cancer is the leading cause of cancer incidence and mortality worldwide. Non-Small Cell Lung Cancer (NSCLC), the major subtype of lung cancer (~85%) usually evolves after oncogenic driver mutations in K-Ras or EGFR, or mutations in tumor suppressor p53 gene. All the aforementioned mutations have been linked with canonical IKKβ/NF-κB pathway activation. NF-κΒ pathways play crucial role in several types of cancer, including NSCLC, but the role of NF-κB target genes remains elusive. The purpose of the current study was to define NF-κB regulated genes during NSCLC development, as possible biological markers or potential therapeutic targets. We have developed, in collaboration, tamoxifen-inducible lung-specific bi-transgenic mice (SPC-CreERT2; IKKβf/f) and showed that IKKβ acts a tumour promoter in NSCLC. We have also developed in vitro doxycycline inducible IKKβKD cell culture models derived from NSCLC cell lines A549, H1299, and H1437. We found that IKKβ knockdown (IKKβKD) had an effect in cell cycle distribution and growth of NSCLC cells. Utilising xenograft mouse models, we confirmed that IKKβKD resulted in the impairment of tumour growth. To define possible targets, we performed Nanostring analysis in A549 IKKβKD cells, and identified several miRNAs showing altered expression, including miR-92b that is down-regulated and miR-32 that is up-regulated. Since IKKβ activates the canonical NF
κΒ signaling pathway, resulting in the nuclear translocation of p65/p50 heterodimers, to investigate whether the effects of IKKβ in NSCLC development is dependent on canonical NF-κΒ signalling, we targeted the RelA/p65subunit in A549, H1299 and H1437 cell lines. Cell cycle analysis showed similar results with IKKβKD cells. Analysis of tumour growth of p65KD grown as in vivo xenografts in NSG/SCID mice confirmed the oncogenic role of canonical NF-κΒ signaling pathway in lung cancer. Next, we performed RNA-sequence analysis from tumours derived from A549 and H1437 p65KD cells grown as in vivo xenografts in mice and compared them to their control counterparts. Analysis of NF-κΒ targeted genes in p65KD cells revealed several induced or down-regulated mRNAs. Specifically, we identified 13 genes in common up-regulated and 10 genes in common down regulated in human A549 and H1437 NSCLC tumours. Some of the up-regulated genes appear to be implicated in immune responses and to have tumour suppressing effects and some of the down-regulated genes exhibit oncogenic properties. The effects of these genes are currently under investigation. Collectively, we uncovered an IKKβ/NF-κB regulatory network, including miRNAs and protein coding genes that hold promise as potential biomarkers and/or therapies for NSCLC.

Tuesday 25 September 2018 16:00 – 17:00 A. Payatakes Seminar Room

“Electrical Tuning of Nonlinearities in Exciton-Polaritons Condensates.”

Dr. Simeon Tzintzos Institute of Electronic Structure and Laser (IESL)

Abstract
A primary limitation of the intensively researched polaritonic systems compared to their atomic counterparts for the study of strongly correlated phenomena and many-body physics is their relatively weak two-particle interactions compared to disorder. In this presentation, we will show how new opportunities to enhance such on-site interactions and nonlinearities arise by tuning the exciton-polariton dipole moment in electrically biased semiconductor microcavities incorporating wide quantum wells. The applied field results in a twofold enhancement of exciton-exciton interactions as well as more efficiently driving relaxation towards low energy polariton states, thus, reducing condensation threshold.

“Nanomaterials in membranes for water treatment and gas separation”

Dr. Konstantinos S. Andrikopoulos Institute of Chemical Engineering Sciences (ICE-HT)

Abstract

Membrane gas separation is an expanding technology with various applications. In many of these applications this technology possesses in addition an energy impact; by the replacement for example of the typical industrial distillation columns that are particularly energy consuming. The specificity of the membrane type for each application is determined by the properties of the materials used as well as their architecture. To this end, new materials would result in an even faster technological growth. Most of the current applications involve CO2 removal or capture and olefin/paraffin separation. Nevertheless, the field of air and natural gas dehydration has shown commercial success as well; mostly based on the overall technologies for separation of solvents forming azeotropes with water. Membrane processes generally require different membranes to be developed for each category of mixture. The most critical parameters that have to be dealt with are selectivity and permeability. Typically these factors are competitive and it’s actually a challenge for a material to enable increase of both factors. Carbon based materials, such as Carbon Nanotubes (CNTs) and Graphene based materials (Graphene, GOs and materials resulting from their structural manipulation) seem to be challenging since they, at least from the theoretical point of view, enable flow of water (and water vapors), which is orders of magnitude higher than the conventional theories of fluids predict. In the current presentation several types of membranes focusing mostly on gas separation and water treatment will be referred. These membranes were developed in the laboratories of FORTH/ICEHT and most of the work that will be presented refers to:

(i) the experimental characterization of the membranes at molecular level in an attempt to describe the mechanisms that rule the processes involved (e.g. how does water vapor transmission rate correlate to the GO structure), (ii) the factors affecting the water vapor permeability in mixed matrix membranes (e.g. the CNTs concentration & dispersion of the CNT-iPP membrane type),
(iii) the methodologies developed in order to non-destructively characterize critical factors (such as the CNTs concentration) that affect the membrane’s operation (e.g. evaluation of CNTs concentration in the selective layer of porous membranes prepared by the phase inversion method)

Monday 16 July 2018 10:00 – 11:00 Seminar room 1

“3D PRINTING OF RESPONSIVE HYDROGELS AND IONOGELS”

Professor Emmanuel P. Giannelis Department of Materials Science and Engineering Cornell University USA

Abstract
Despite extensive progress to engineer hydrogels for a broad range of technologies, practical applications have remained elusive due to their (until recently) poor mechanical properties and lack of fabrication approaches, which constrain active structures to simple geometries. Stereolithography, SLA, has demonstrated extreme promise because of its ability to selectively create a desired structure layer-by-layer out of a liquid pre-gel solution under exposure to patterned light. As such SLA is an attractive manufacturing technique for rapid prototyping and the fabrication of customizable items like biomedical implants or scaffolds. In this presentation, I will review our efforts to develop ionic polymer nanocomposite systems and then focus on our more recent work on systems adaptable to 3D printing. These new nanocomposite hydrogels and ionogels combine within a single platform tunable stiffness, toughness, extensibility, and resiliency. In addition to their excellent mechanical performance, they exhibit fast printing, conductivity, and fast osmotically-driven actuation. The tunable properties combined with the ability for 3D-printing into complex architectures, provide opportunities for a variety of practical applications such as artificial tissue, soft actuators, compliant conductors, and sensors for soft robotics.

Speaker: Dr. Violakis George
Affiliation: Institute of Electronic Structure and Laser (IESL)

Title: Novel sensing and actuating optical fiber devices

Place: A. Payatakes Seminar Room

Date: 10/07/2018
Time: 16:00 (coffee & cookies at 15:45)

Abstract:
In a world with steadily increasing energy demands, miniaturization and optimization of energy efficiency is becoming a key design element of devices. Optical fibers have proven excellent platforms for the realization of miniature, flexible and energy efficient sensors and actuators. In this work we present two different classes of optical fiber based devices: First, a miniature magnetic field sensor with field amplitude and direction sensing capability, realized by encapsulating ferrofluids on a D-shaped optical fiber. The total footprint of this sensor is of the order of a few hundred micrometers with possible applications in magneto-optical switching or sensing. Second, a novel-photonic bandgap optical fiber is presented, which was realized by infiltrating 2-methyl 4-nitroaniline (MNA) in the capillaries of a commercially available microstructured optical fiber. The resulting composite fiber exhibits a wavelength dependent guidance mechanism and second harmonic generation, both of which depend on MNA solidification inside the fiber capillaries. Post processing the composite fiber by means of thermal annealing and poling is used to alter the structure of the MNA material in the capillaries which affects both fiber transmittance characteristics and second harmonic generation efficiency. Such a type of optical fiber could be used in all-optical gating and wavelength conversion devices.

Speaker: Dr. Eugene Skouras
Affiliation: Institute of Chemical Engineering Sciences (ICE-HT)

Title: Simulation of transport and reaction processes

Place: “Stelios Orphanoudakis” Seminar Room

Date: 03/07/2018
Time: 16:00 (coffee & cookies at 15:45)

Abstract: Aided by modern hardware and software advances, state-of-the-art computational techniques and virtual reconstructions have emerged recently as essential tools for the design of novel or improved materials, and for the discovery of innovated or enhanced properties of existing ones, successively corroborated by experimentation. Candidates for components with enhanced properties and processes with elevated performances are often suggested, designed and screened through simulations, even ahead or in place of usually strenuous and costly synthesis and characterization experiments. Extensive knowledge of key aspects and mechanisms of the flow, transport, sorption and separation phenomena in the interior of membranes on micro- and nanoscales is able to provide valuable insights on a significant number of processes related to porous membranes, and facilitate membrane design and optimization. Recent studies have shown that the efficiency of modern hemodialysis processes is controlled by module geometry, membrane properties, and operating conditions. Optimization of membrane performance usually requires extensive and laborious experimentation. Detailed mathematical models are often necessary to predict the performance of hemodialysis operation under various operational conditions at more affordable accuracy and time scales. The primary purpose of this line of work is to develop detailed models that will predict the removal of blood toxins during hemodialysis using multi-layered mixed matrix membranes. The modeling and simulation background of relevant membrane separation processes will be presented, and focus will be placed on the computer-aided reconstruction of porous membranes for controlled transport and separation of biological fluids, along with the development of models and algorithms for the simulation of protein-bound toxin dissociation, transport, and sorption phenomena in digitized porous membranes either impregnated with sorbents or coupled with living cells for blood purification.

Tuesday 18 June 2018 16:00 – 17:00 A. Payatakes Seminar Room

“From Games to Algorithms, Telecommunications and Machine Learning”

Dr. Fasoulakis Michail Institute of Computer Science (ICS)

Abstract
Game theory is the area of mathematics for analysing conflict and cooperation situations. One of the most reasonable solution concepts in game theory is the Nash equilibrium, a stable solution that no player has any incentive to deviate. Nash equilibria could a priori predict what rational players should do in a competitive situation. But what is the prediction power if we cannot compute them? The problem of computing a Nash equilibrium is now known to be complete in the computational complexity class PPAD, that makes the area of computing approximate Nash equilibria one of the most important areas in equilibrium computation. We will present the state-of-the-art in computation of approximate Nash equilibria. At the second part of the presentation, we will show applications of (algorithmic) game theory in the area of telecommunications, for instance in a museum environment. Furthermore, we will present a game theoretic study of jamming in multiple Gaussian independent channels and finally, we will present the Generative Adversarial Networks and the formulation of them as zero-sum game in the intersection of game theory and machine learning.

Speaker: Dr. Nikolaos Koromilas
Affiliation: Institute of Chemical Engineering Sciences (ICE-HT)

Title: Development of Polymeric Membranes for water purification

Place: A. Payatakes Seminar Room

Date: 12/06/2018
Time: 16:00 (coffee & cookies at 15:45)

Abstract: Water pollution is one of the most critical global challenges in the modern era. The need for an adequate supply of clean water has led to new emerging technologies. Due to its energy-saving and cost-effective features, membrane technology has become the most effective platform for water purification, including seawater as well as municipal or industrial wastewater treatment. Among them, organic polymeric membranes possess several advantages against inorganic membranes. In the present work, polymeric membranes based on a polysulfone-based polymeric matrix were successfully prepared via non-solvent induced phase separation (NIPS) method.

The polysulfonetype polymer poly[2-(4-(diphenylsulfonyl)phenoxy)-6-(4-phenoxy)pyridine] (PDSPP) was used as the hydrophobic matrix and combined with its sulfonated derivative (SPDSPP) and a polymeric porogen in order to enhance the hydrophilicity and increase the porosity of the overall membrane system. The variables tested included PDSPP/SPDSPP/porogen w/w composition, type of porogen, type of solvent, type and temperature of nonsolvent, etc. Scanning Electron Miscroscopy (SEM), Scanning Electron Miscroscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS), Water Uptake % (WU %), Porosity %, Pure Water Flux (PWF), Pure Water Permeability (PWP), Attenuated Total Reflectance-Infrared Spectroscopy (ATR-IR) and Thermogravimetric Analysis (TGA) were the driving procedures and techniques used to evaluate the impact of the different parameters. The results shown that using different conditions the morphology of the membranes can be altered and therefore optimized, making them ideal candidates for water purification membranes.

Speaker: Dr. Emmanouil Glynos
Affiliation: Institute of Electronic Structure and Laser (IESL)

Title: High Performance Solid Polymer Electrolytes for Energy Storage via Macromolecular Engineering

Place: A. Payatakes Seminar Room

Date: 05/06/2018
Time: 16:00 (coffee & cookies at 15:45)

Abstract: Climate change, pollution and declining fossil resources are overwhelming challenges to humankind. Gaseous emission from burning fossil fuels pollutes the air in large modern cities creating a global warming with alarming climate changes. These concerns have led to national initiatives to reconsider the use of alternative energy sources such as solar radiation, wind, and waves. However, the intermittence of these resources (their variability in time and wide distribution in space) requires high energy storage systems. To this end, secondary batteries based on lithium metal anodes are the most sought-after candidates for next-generation storage systems since they can store a large amount of energy per unit mass or volume. However, unstable electrodeposition and uncontrolled interfacial reactions occurring in conventional liquid electrolytes cause unsatisfying cell performance and major safety concerns.

Solid polymer electrolytes (SPEs) could be a “real game-changer” as they hold the promise to solve most of the problems of liquid electrolytes. SPEs are inherently safe, nonflammable and compatible with lithium metal anodes. Despite the considerable research effort in SPEs, the primary challenge is the development of solid materials with good mechanical properties without sacrificing ionic-conductivity. In this talk, the use of novel polymer nanostructured nanoparticles will be introduced as additives to liquid electrolytes for the synthesis of SPEs that exhibit an unprecedented combination of high modulus and ionic conductivity. The nanoparticles are composed of high functionality mikto-arm star copolymers in which stiff insulating arms complement ion conducting arms. Because of their molecular design and their colloid-like structure, the materials constitute the first example of allpolymer nanostructured materials where each and every building block is a nano-sized polymeric nanostructured “molecular material”. It will be demonstrated that the final/desired morphology and phase dimensions of the SPEs may be precisely controlled as is encrypted within the macromolecular characteristics and the chemical composition of the “nanoparticles”. As the synthesis of mechanical robust electrolytes with superior ion-conductivity has been the subject in a wide variety of solid-state electrochemical devices, this approach may significantly contribute to other applications, beyond lithium metal batteries, such as anion exchange membranes for fuel cells, efficient active layers in dye-sensitized solar cells, electrochromic devices and water desalination systems.

Speaker: Dr. George Tserevelakis
Affiliation: Institute of Electronic Structure and Laser (IESL)

Title: Listening to laser light interactions with objects of art: A novel photoacoustic diagnosis approach

Place: A. Payatakes Seminar Room

Date: 29/5/2018
Time: 14:00 (coffee & cookies at 13:45)

Abstract:

Photoacoustic imaging constitutes a novel, rapidly expanding diagnostic technique, which has been predominantly developed in the context of contemporary biomedical research. Recent implementations of various photoacoustic imaging systems have enabled high resolution in vivo imaging of intrinsic biological absorbers such as hemoglobin, melanin and lipids at various spatial scales ranging from cells and tissues to small animals.

In this presentation, I will demonstrate how photoacoustic imaging can break the barriers of biomedicine, and find innovative applications in cultural heritage (CH) diagnostics. Having over three orders of magnitude higher transmission through strongly scattering media compared to light in the visible and near infrared, the photoacoustic signal offers substantially improved detection sensitivity and achieves excellent optical absorption contrast at high spatial resolution.
In the first part of the talk, I will show that such a unique combination of advantages can be exploited to establish a radically new non-destructive methodology for the uncovering and differentiation of well-hidden features in multi-layered CH objects such as paintings and documents. Furthermore, I will demonstrate that the attenuation of the generated photoacoustic signals during their propagation through optically opaque media (e.g. paints) can be used to determine the thickness of thin layers, providing, in this manner, micrometric precision stratigraphic information on the artwork under investigation. Finally, I will present the capabilities of photoacoustic signal detection on the in situ real-time monitoring of laser cleaning interventions, which has the potential to promote an improved conservation outcome by safeguarding artworks’ original surfaces.