The effect of stellar contamination on low-resolution transmission spectroscopy: needs identified by NASA’s Exoplanet Exploration Program Study Analysis Group 21

Study Analysis Group 21 (SAG21) of NASA’s Exoplanet Exploration Program Analysis Group was organized to study the effect of stellar contamination on space-based transmission spectroscopy, a method for studying exoplanetary atmospheres by measuring the wavelength-dependent radius of a planet as it transits its star. Transmission spectroscopy relies on a precise understanding of the spectrum of the star being occulted. However, stars are not homogeneous, constant light sources but have temporally evolving photospheres and chromospheres with inhomogeneities like spots, faculae, plages, granules, and flares. This SAG brought together an interdisciplinary team of more than 100 scientists, with observers and theorists from the heliophysics, stellar astrophysics, planetary science, and exoplanetary atmosphere research communities, to study the current research needs that can be addressed in this context to make the most of transit studies from current NASA facilities like Hubble Space Telescope and JWST. The analysis produced 14 findings, which fall into three science themes encompassing (i) how the Sun is used as our best laboratory to calibrate our understanding of stellar heterogeneities (‘The Sun as the Stellar Benchmark’), (ii) how stars other than the Sun extend our knowledge of heterogeneities (‘Surface Heterogeneities of Other Stars’), and (iii) how to incorporate information gathered for the Sun and other stars into transit studies (‘Mapping Stellar Knowledge to Transit Studies’). In this invited review, we largely reproduce the final report of SAG21 as a contribution to the peer-reviewed literature

Alien Registration- Korhonen, Elsa M. (Norway, Oxford County)

https://digitalmaine.com/alien_docs/20918/thumbnail.jp

Covalent functionalization of graphene oxide with proteins

Pro gradu -tutkielman kirjallisuusosassa perehdyttiin menetelmiin, jotka voisivat soveltua proteiinien kiinnittämiseen grafeenioksidin pintaan kovalenttisen sitoutumisen kautta. Kokeellisessa osassa oli tavoitteena kiinnittää linkkerimolekyylien avulla piparjuuriperoksidaasi (HRP) -entsyymimolekyylejä laserilla hapetetun grafeenin pintaan. Alustavissa kokeissa testattiin kahta menetelmää HRP:n kiinnittämiseksi grafeenioksidihiutaleisiin. Menetelmät erosivat käytettyjen linkkerimolekyylien suhteen. Ensimmäisessä menetelmässä käytettiin glutaraldehydiä ja toisessa APTES:sta ja glutaraldehydistä muodostuvaa linkkeriä. Termogravimetrinen analyysi ja FTIR-mittausten tulokset viittasivat kovalenttisten sidosten muodostumiseen grafeenioksidin ja linkkerien sekä linkkerien ja HRP:n välille. Glutaraldehydiin perustuva menetelmä valittiin varsinaiseen kokeeseen, jossa käytettiin laserilla käsiteltyä grafeenipohjaista mikrosirua. Mikrosirusta otetuista AFM-kuvista havaittiin kohonneita viivamaisia ja pistemäisiä rakenteita funktionalisoinnin jälkeen, joiden pääteltiin olevan glutaraldehydiketjuja ja HRP-proteiinimolekyylejä. Mikrosirun hapetetuista alueista mitatut Raman-spketrit viittasivat muutoksiin hapetetun grafeenin elektronirakenteessa: D-, G- ja 2D-vöiden Raman-siirtymät pienenenivät ja D-vyön pinta-ala kasvoi funktionalisoinnin jälkeen. Muutosten pääteltiin johtuvan grafeenioksidin ja linkkerien tai HRP:n välisistä vuorovaikutuksista. Tulosten perusteella ei kuitenkaan voitu varmistaa HRP:n kovalenttista kiinnittymistä mikrosirun grafeenioksidipintaan glutaraldehydin välityksellä.The literature part of the master’s thesis focuses on introducing potential functionalization methods for the covalent attachment of proteins on graphene oxide (GO) surfaces. The experimental part aimed at the covalent immobilization of horseradish peroxidase (HRP) on the laser-oxidized graphene-based microchip. Based on the preliminary studies with graphene oxide flakes, both crosslinker systems, glutaraldehyde (GA) and APTES-glutaraldehyde, resulted in a similar outcome of the HRP immobilization. The thermogravimetric analysis and FTIR spectroscopic results suggested the formation of covalent bonds between the components of the GO-crosslinker-HRP systems. The GA-based crosslinking method was chosen for the protein immobilization studies with the graphene-based microchip. From the atomic force microscopy (AFM) images of the microchip after the treatment with GA and HRP solutions (in PBS buffer), line-shaped structures and elevated dots could be observed, assigned to be GA crosslinkers and HRP protein molecules, respectively. The Raman spectra of the oxidized areas showed shifting of the D, G, and 2D bands towards lower Raman shifts after HRP immobilization, which agree with the former results, indicating a successful immobilization of HRP. Also, the D band areas of the oxidized regions increased after HRP immobilization, suggesting an increased number of defects in the graphene lattice. Based on the AFM and Raman spectroscopy results from the experiments with the chip, the covalent attachment of HRP to the chip’s surface via GA crosslinker could not be fully proved

Hydrogeelit hermosolujen kasvatuksessa

Tässä kirjallisuuskatsauksessa käsitellään hermosolukasvatukseen soveltuvia hydrogeelejä, jotka on jaettu synteettisiin ja luontaisiin hydrogeeleihin sekä grafeeni- ja hiilinanoputkipohjaisiin hybridihydrogeeleihin. Tutkielmassa keskitytään siihen, miten hydrogeelien ominaisuudet, kuten hajoamisnopeus, huokoskoko ja sähkönjohtokyky, vaikuttavat hermosolujen kasvuun. Tutkimusten perusteella hermosoluille suotuisin kasvualusta on hybridihydrogeelit, jotka sisältävät vähintään kahta seuraavista komponenteista: hiilinanoputkia, grafeenikomponentteja, synteettisiä tai luontaisia polymeerejä

Alien Registration- Korhonen, Elsa M. (Norway, Oxford County)

https://digitalmaine.com/alien_docs/20918/thumbnail.jp

Solvent-induced transient self-assembly of peptide gels: gelator-solvent reactions and material properties correlation

Herein, we introduce a new methodology for designing transient organogels that offers tunability of the mechanical properties simply by matching the precursor’s protective groups to that of the solvent. We developed solvent-induced transient materials in which the solvent chemically participates in a set of reactions and actively supports the assembly event. The activation of a single precursor by an acid (accelerator) yields the formation of two distinct gelators and induces gelation. The interconversion cycle is supplied by the secondary solvent (originating from the hydrolysis of the primary solvent by the accelerator), which then progressively solubilizes the gel network. We show that this gelation method offers a direct correlation between the mechanical and transient properties by modifying the chemical structure of the precursors and the presence of accelerator in the system. Such a method paves the way for designing self-abolishing and mechanically tunable materials for targeted purposes. The biocompatibility and versatility of amino acid-based gelators can offer a wide range of biomaterials for applications requiring a controllable and definite lifetime, such as drug delivery platforms exhibiting a burst release or self-abolishing cell culture substrate