Equilibrium and Transport Properties of Systems Containing Graphene Sheets (-Oil Nanocomposites and Membranes) from Molecular Dynamics Simulations

Graphene sheets belong to an interesting class of materials. Their exceptional properties, including high thermal and electrical conductivity, mechanical strength etc., could play an important role in multiple applications, suggesting the possible use of graphene sheets in, e.g., electronic devices, nanocomposites, energy storage, and membranes for water desalination, to name just a few. Understanding the properties of graphene is essential to secure progress in all these areas. Molecular dynamics simulations were performed to provide molecular level insights of the equilibrium and transport properties of several systems containing graphene sheets.In the first part of the thesis graphene-oil nanocomposites are considered. Results show that it is possible to obtain stable dispersions of graphene sheets in oils such as n-hexane, n-octane and n-dodecane by appropriately functionalizing the edges of the graphene sheets with short branched alkanes. Excluded-volume effects, generated by the branched architecture of the functional groups grafted on the graphene sheets, are responsible for the stabilization of small graphene sheets in the organic systems considered here. Using non-equilibrium molecular dynamics, the Kapitza resistance at the graphene-octane and graphene-graphene interfaces was calculated. Our results demonstrate that it is possible to reduce the Kapitza resistance at the graphene sheet-octane interface by using the functionalized graphene sheets, but the functional groups must show vibrational modes compatible with those of the organic matrix. A higher value of Kapitza resistance for graphene sheets in vacuum compared to that in octane was found because the graphene-graphene interface has larger Kapitza resistance than the graphene-octane interface, which is consistent with observations for carbon nanotube – carbon nanotube contacts. More importantly, the Kapitza resistance for the graphene-graphene contact can be 30% lower than values reported for the carbon nanotube – carbon nanotube contact. Equilibrium and non-equilibrium molecular dynamics simulations to assess the effective interactions between dispersed graphene sheets, the self-assembly of graphene, and the heat transfer through the graphene-octane nanocomposite. Evidence is provided for the formation of nematic phases when the graphene sheets volume fraction increases within octane. The atomic-level results are input for a coarse-grained Monte Carlo simulation that predicts anisotropic thermal conductivity for graphene-based composites when the graphene sheets show nematic phases. Overall, these results suggest that it might be possible to produce nanocomposites containing graphene sheets. Such materials could show exceptional mechanical and thermal-transport properties (due to the inclusion of graphene sheets), while maintaining the lightweight typical of polymeric materials.In the second part of the thesis umbrella sampling simulations were employed to study the transport of water molecules and ions through the membranes incorporating bare and functionalized graphene pores. By calculating the potential of mean force for ion and water translocation through the bare graphene pores, we show that ions face a large energy barrier and will not pass through the narrower pore studied (Ø ~ 7.5 Å) but can pass through the wider pores (Ø ~ 10.5 and 14.5). Water, however, faces no such impediment and passes through all the pores studied with little energy barrier. When charged groups are grafted to the pore rim, the results show that the charges can help to prevent the passage of ions. Comparison of results for graphene pore to that of carbon nanotube pore reveals that COO- groups are more effective when grafted to the rim of GS pore in preventing Cl- ions from passing through the membrane compared to that of carbon nanotube pore. The results presented could be useful for the design of water desalination membranes

Divide And Conquer Algorithm Based an Efficient Scheme for Compression of Electro Cardiac Signal

An electrocardiogram (ECG) is a standard test that checks how the heart is working by measuring the electrical action of the heart. Individuals with a heart related issues have the long record of ECGs for symptomatic purposes, which brings about the necessity of a lot of storage space. Subsequently there is a requirement for a framework which includes pressure of ECG signals alongside ECG investigation. ECG pressure is a superior technique for minimize computational many-sided quality as far as storage. Flag pressure and flag examination have request in numerous application territories particularly in biomedical zone. ECG signals are diverse for every individual. ECG design acknowledgment is a standout amongst the most dependable coronary illness recognizable proof strategies. ECG is the standard tool for monitoring and diagnosing cardiovascular issues by measuring electrical movement of the heart. The cathodes connected to the body identify the electrical movement of the heart. From every terminal the ECG signals will record and store for a drawn out stretch of time

Atmospheric composition of exoplanets based on the thermal escape of gases and implications for habitability

Funding: This research has been funded by the Knut and Alice Wallenberg Foundation, Kempe Foundation, The County Administrative Board of Norrbotten and Luleå University of Technology. M.-P.Z.'s research at CAB has been partially supported by the Spanish State Research Agency (AEI) project no. MDM-2017-0737 Unidad de Excelencia ‘María de Maeztu’- Centro de Astrobiología (INTA-CSIC). Acknowledgements: We thank all the referees for their valuable comments. We are grateful for their constructive remarks, which led to a significant improvement to the manuscript.Peer reviewedPublisher PD

Interactive IPA Chart to Improve English Pronunciation of ESL Students – An Experimental Study

Achieving goals practically in a reproducible way by applying knowledge is possible using technology. Teaching English is not an exception in applying technology for effective results. In the field of English Language Teaching (ELT), very few teachers focus on teaching English pronunciation. Though this aspect of ELT is rare, it has become a vital aspect of ELT in today’s world due to globalization of English language and enormous use of English in everyday life. The present time can be considered as a golden era for learning as our lives are aided by technology. As we use technology abundantly every day, it is not wrong to use the same for learning. In fact, teaching and learning can be effective when they are aided by technology. Moreover, CALL (Computer Assisted Language Learning) is one of the approaches in ELT, used widely by innovative teachers and learners of English, proved to be an efficient approach than traditional methods of teaching IPA. So, the present work is focused on teaching English pronunciation for ESL students using interactive IPA chart assisted by pre-test, intervention study, and post-test to analyse and attempt to meet the needs of students in learning English pronunciation. In order to check the effectiveness of the use of IPA chart, first, a pre-test was conducted with words focusing the pronunciation of all the 44 sounds of English to analyse the deviation of students’ pronunciation from the Received Pronunciation (RP). Then, based on the outcome of pre-test, an intervention study was conducted to provide the necessary input to address the students’ pronunciation problems. At this stage, students were taught all the 44 sounds of English using interactive IPA chart, so that they can clearly distinguish the differences between the sounds of English and the sounds of their mother-tongue. These subtle differences are often not paid attention due to ignorance, confusion, mispronunciation and mother-tongue influence. After proper leaning is achieved by the students, a post-test was conducted which helped to analyse the improvement in students’ pronunciation. Upon achieving improved performance in students’ pronunciation, it can be clearly concluded that use of interactive IPA chart in teaching English pronunciation for ESL students is one of the innovative ways to teach English pronunciation to the students with effectiveness and ease. This would really help the future teachers of English and students

The Impact of the Spectral Radiation Environment on the Maximum Absorption Wavelengths of Human Vision and Other Species

Funding: This research was funded by the Knut and Alice Wallenberg Foundation, The County Administrative Board of Norrbotten and Luleå University of Technology. M.-P.Z.’s research at CAB was partially supported by the Spanish State Research Agency (AEI), project no. MDM-2017-0737 Unidad de Excelencia ‘María de Maeztu’- Centro de Astrobiología (INTA-CSIC). Acknowledgments: The authors acknowledge support from the Wallenberg Foundation (KAW 2016.0346).Peer reviewedPublisher PD

IN SITU GEL POLYMERS: A REVIEW

In situ gels have become one of the most prominent and accessible systems. These systems have several advantages like simple manufacturing, easy to use, improved adherence, and patient comfort by minimizing drug administration frequency by its unique characteristic features of sol to gel transition. In the 'sol-gel' method, the precursor goes through hydrolysis and polymerization or condensation to produce a colloidal suspension or solution. As they can administer in solution form, these in situ gelling systems undergo gelation at the achievement site. Some researchers recently developed in situ gelling systems of liposomes, microspheres, nanoemulsions, nanospheres, etc. This review mainly focused on the introduction, advantages, disadvantages, types of polymers, and suitable characteristics for preparing in situ gels

SENSOR APPLICATIONS IN ANALYSIS OF DRUGS AND FORMULATIONS

Several sensors, biosensors, and actuators are designed and mounted to analyze biomedical nutraceuticals, food, and nutraceutical products in this particular issue. Some applications concern classical subjects such as eubacteria determination in agricultural products, flashing material in foods such as the ethyl group’s chemicals, and fruit juices’ inhibitor properties. In contrast, the different applications are more revolutionary, such as safety research, the manufacture of artificial human senses (electronic nose or tongue), or t Ligands are often characterized by nano biosensors, utilizing biomaterials that involve specific aptamers, antibodies, enzymes, polymers, and sensory receptors. The square measurement of several modal sensing elements, integrated with nanomaterials, increases sensitivity such as nano biosensors and increases nano biosensor productivity. For the nano biosensor with increased efficiency, modality sensing components have been incorporated in this case. The square measurement of the elastic (ME) magnetic machine biosensors was used to classify infectious agents by a magnet coil in contemporary juice or milk and to develop direct detection of infectious agents on food scanning coils

The HABIT (HabitAbility: Brine Irradiation and Temperature) environmental instrument for the ExoMars 2022 Surface Platform

Acknowledgements HABIT is an instrument of the Luleå University of Technology (LTU), led by J. Martín-Torres (PI) and M-P. Zorzano (co-PI). The international list of Co-Is and collaborators of the science team of HABIT is given in (https://atmospheres.research.ltu.se/habit/pages/team.php). HABIT engineering team: A. Soria-Salinas, M. I. Nazarious, S. Konatham, T. Mathanlal and A. Vakkada Ramachandran. HABIT IT team: J. –A. Ramirez-Luque and R. Mantas-Nakhai. ASS acknowledges the support of the LTU Graduate School of Space. M-P. Z's contribution has been partially supported by the Spanish State Research Agency (AEI) Project No. MDM-2017-0737 Unidad de Excelencia “María de Maeztu” - Centro de Astrobiología (INTA-CSIC). The HABIT FM and EQM were fabricated by Omnisys Instruments AB, based in Gothenburg, Sweden, under advice of LTU as part of the HABIT project development and funded by the Swedish National Space Agency (SNSA). We thank the ExoMars project team, European Space Agency (ESA), Roscosmos, Space Research Institute (IKI) and Omnisys Instruments AB for their hard work on the ExoMars mission. We thank Petra Rettberg and Carina Fink from DLR for their planetary protection analysis of HABIT samples. We acknowledge the Luleå University of Technology, the Wallenberg Foundation and the Kempe Foundation for support of the Mars research activities. We thank the support of the Swedish Institute for Space Physics (IRF) for the TVAC tests. The Oxia Planum environmental conditions research was partially funded by the European Research Foundation. The SpaceQ chamber has been developed together with Kurt J. Lesker Company and was funded by the Kempe Foundation. CRediT authorship contribution statement Javier Martín-Torres: Conceptualization, Methodology, Supervision, Investigation, Writing - original draft, Funding acquisition, Resources, Project administration. María-Paz Zorzano: Conceptualization, Methodology, Supervision, Investigation, Writing - original draft, Funding acquisition, Resources, Project administration. Álvaro Soria-Salinas: Formal analysis, Investigation, Visualization, Writing - review & editing. Miracle Israel Nazarious: Formal analysis, Investigation, Visualization, Writing - review & editing. Samuel Konatham: Formal analysis, Investigation, Visualization, Writing - review & editing. Thasshwin Mathanlal: Formal analysis, Investigation, Visualization, Writing - review & editing. Abhilash Vakkada Ramachandran: Formal analysis, Investigation, Visualization, Writing - review & editing. Juan-Antonio Ramírez-Luque: Software, Writing - review & editing. Roberto Mantas-Nakhai: Software, Writing - review & editing.Peer reviewedPostprin

Thermal Properties of Graphene, Carbon Nanotubes and Nanostructured Carbon Materials

Recent years witnessed a rapid growth of interest of scientific and engineering communities to thermal properties of materials. Carbon allotropes and derivatives occupy a unique place in terms of their ability to conduct heat. The room-temperature thermal conductivity of carbon materials span an extraordinary large range - of over five orders of magnitude - from the lowest in amorphous carbons to the highest in graphene and carbon nanotubes. I review thermal and thermoelectric properties of carbon materials focusing on recent results for graphene, carbon nanotubes and nanostructured carbon materials with different degrees of disorder. A special attention is given to the unusual size dependence of heat conduction in two-dimensional crystals and, specifically, in graphene. I also describe prospects of applications of graphene and carbon materials for thermal management of electronics.Comment: Review Paper; 37 manuscript pages; 4 figures and 2 boxe

Graphene -- Based Nanocomposites as Highly Efficient Thermal Interface Materials

We found that an optimized mixture of graphene and multilayer graphene - produced by the high-yield inexpensive liquid-phase-exfoliation technique - can lead to an extremely strong enhancement of the cross-plane thermal conductivity K of the composite. The "laser flash" measurements revealed a record-high enhancement of K by 2300 % in the graphene-based polymer at the filler loading fraction f =10 vol. %. It was determined that a relatively high concentration of single-layer and bilayer graphene flakes (~10-15%) present simultaneously with thicker multilayers of large lateral size (~ 1 micrometer) were essential for the observed unusual K enhancement. The thermal conductivity of a commercial thermal grease was increased from an initial value of ~5.8 W/mK to K=14 W/mK at the small loading f=2%, which preserved all mechanical properties of the hybrid. Our modeling results suggest that graphene - multilayer graphene nanocomposite used as the thermal interface material outperforms those with carbon nanotubes or metal nanoparticles owing to graphene's aspect ratio and lower Kapitza resistance at the graphene - matrix interface.Comment: 4 figure