Chemical Self Assembly of Graphene Sheets

Chemically derived graphene sheets were found to self-assemble onto patterned gold structures via electrostatic interactions between noncovalent functional groups on GS and gold. This afforded regular arrays of single graphene sheets on large substrates, characterized by scanning electron and Auger microscopy imaging and Raman spectroscopy. Self assembly was used for the first time to produce on-substrate and fully-suspended graphene electrical devices. Molecular coatings on the GS were removed by high current electrical annealing, which recovered the high electrical conductance and Dirac point of the GS. Molecular sensors for highly sensitive gas detections are demonstrated with self-assembled GS devices.Comment: Nano Research, in press, http://www.thenanoresearch.co

Basic and translational studies on species B adenoviruses

Human adenoviruses (Ads) have been classified into six species (A to F) currently containing 55 serotypes. For almost 2 decades vectors derived from group C serotype Ad5 have been extensively used for gene transfer studies. These Ad5 based vectors are able to efficiently infect many mammalian cell types (including both mitotic and post-mitotic cells) through interaction with a primary attachment receptor, the coxsackie and adenovirus receptor (CAR). Despite the many advantages of Ad5 based vectors a number of limitations have affected their therapeutic application to many diseases. Although they can transduce many tissue types, Ad5 based vectors are unable to efficiently transduce several potential disease target cell types, including hematopoietic stem cells and malignant tumor cells. Therefore, newer vectors have been developed based on Ad serotypes other than Ad5. This thesis focuses on species B Ads. Species B Ads are comprised of three groups based on their receptor usage. Group 1 of species B Ads (Ad16, 21, 35, 50) nearly exclusively utilize CD46 as a receptor; Group 2 (Ad3, Ad7, 14) share a common, unidentified receptor/s, which is not CD46 and which was tentatively named receptor X; Group 3 (Ad11) preferentially interacts with CD46, but also utilizes receptor X if CD46 is blocked. Species B group Ads are important human pathogens. Species B group 2 serotypes are isolated from patients with respiratory tract infections, whereas the Group 1 viruses are described as causing kidney and urinary tract infections. B-group Ad infections often occur in immunocompromised patients, including AIDS patients, recipients of bone marrow transplants, or chemotherapy patients. Recent studies performed in U.S. military training facilities indicate an emergence of diverse species B serotypes at the majority of sites. This included the group 1 serotype 21 and the group 2 serotypes 3, 7, and 14. CD46-targeting vectors derived from Ad35 and Ad11 are important tools for in vitro gene transfer into human stem cells, including hematopoietic stem cells and induced pluripotent stem cells. Ad35 and Ad11 have been used as tools for cancer therapy, because CD46 appears to be uniformely overexpressed on many cancers. Furthermore, receptor X-targeting vectors, i.e vectors derived from Ad3 or vectors containing Ad3 fibers have shown superior in the transduction of tumor cells both in vitro and in vivo and are currently being used clinically in cancer patients. While extensive basic virology studies have been done on Ad5, the information of species B group 1 interaction with CD46 is limited. Furthermore, the receptor for a major subgroup of species B Ads (receptor X) is unknown. The goal of this thesis was it therefore to better understand virological and translational aspects of species B Ads. The specific findings described in this thesis include i) the identification of CD46 binding sites within the Ad35 fiber knob, ii) the study of the in vitro and in vivo properties of Ad vectors with increased affinity to CD46. iii) the study of the receptor usage of a newly emergent Ad14a, iv) the identification of desmoglein 2 as the receptor for Ad3, Ad7, Ad11, and Ad14, v) the delineation of structural details of Ad3 virus interaction with DSG2, and vi) the analysis of functional consequences of Ad3-DSG2 interaction. As a result of these basic virology studies two Ad-derived recombinant proteins have been generated that can be used to enhance cancer therapy by monoclonal antibodies.Ihmisen adenovirukset (Ad) on jaoteltu kuuteen ryhmään (A-F) jotka pitävät sisällään kaikkiaan 55 viruksen serotyyppiä. C-ryhmään kuuluvaa serotyyppi 5- adenovirusta (Ad5) on käytetty yleisesti geeninsiirtotutkimuksissa lähes kahden vuosikymmenen ajan. Ad5:een perustuvat vektorit pystyvät infektoimaan tehokkaasti monia nisäkässolutyyppejä (sekä jakaantuvia että jakaantumattomia) ensisijaisen reseptorinsa, coxsackie- ja adenovirusreseptorin (CAR) kautta. Lukuisista eduistaan huolimatta Ad5-pohjaisissa geeninsiirtovektoreissa on myös monia puutteita jotka rajoittavat useiden sairauksien kohdalla niiden hoidollista käyttöä. Vaikka ne pystyvät infektoimaan monia solu- ja kudostyyppejä, on myös monia sairauksia joiden kohdesoluja ne eivät tehokkaasti infektoi. Esimerkkeinä tällaisista mainittakoon veren kantasolut ja syöpäsolut. Rajoitteiden vuoksi uusia geeninsiirtovektoreita on alettu kehittämään Ad5:en ohella myös muista adenoviruksen serotyypeistä. Tämä väitöskirja keskittyy B-ryhmään kuuluviin adenoviruksiin, jotka on luokiteltu reseptoreidensa perusteella kolmeen alaryhmään. Näistä ensimmäinen (Ad16, Ad21, Ad35 ja Ad50) sitoutuu lähes yksinomaan CD46-reseptoriin. Toinen alaryhmä (Ad3, Ad7 ja Ad14) sitoutuvat yleiseen mutta vielä tuntemattomaan reseptoriin tai reseptoreihin, joka ei ole CD46-reseptori, ja joka alustavasti nimettiin reseptoriksi X. Kolmas alaryhmä (Ad11) sitoutuu CD46:een, mutta estettäessä sitoutuminen CD46:een se sitoutuu myös reseptori X.ään. Ad5:a on käytetty laajalti perusvirologian tutkimuksissa, mutta myös B-ryhmän adenovirukset ovat yleisiä taudinaiheuttajia ihmisessä. Ryhmän B alaryhmän 1 serotyyppien suhteesta reseptori CD46:een ei tiedetä paljoa. Yleisemmin, suurelta osalta B-ryhmän viruksia niiden reseptori on jäänyt selvittämättä (reseptori X).Tämän väitöskirjan tavoite olikin tutkia lähemmin ryhmän B adenovirusta sekä virologisin että translationaalisin menetelmin. Väitöskirjassa tutkittiin seuraavia asioita: i) paikannettiin Ad35-viruksen CD46:een sitoutuva alue, ii) tutkittiin in vitro ja in vivo-ominaisuuksia jotka vahvistavat viruksen sitoutumista CD46-reseptoriin, iii) tutkittiin vastikään löydetyn Ad14a-serotyypin reseptorinkäyttöä, iv) tunnistettiin desmogleiini-2 (DSG2) reseptoriksi Ad3, Ad7, Ad11 ja Ad14:lle, v) selvitettiin Ad3-DSG2-sitoutumiseen liittyviä rakenteellisia yksityiskohtia, ja vi) analysoitiin Ad3-DSG2-sitoutumisen toiminnallisia seuraamuksia. Näiden perusvirologisten tutkimusten perusteella on luotu kaksi Ad-pohjaista rekombinanttiproteiinia joilla voidaan tehostaa syövän hoitoa monoklonaalisilla vasta-aineilla

XPS study of nanostructured surface-Co on Si(100)

Master'sMASTER OF SCIENC

Thermal Conductance of an Individual Single-Wall Carbon Nanotube above Room Temperature

The thermal properties of a suspended metallic single-wall carbon nanotube (SWNT) are extracted from its high-bias (I-V) electrical characteristics over the 300-800 K temperature range, achieved by Joule self-heating. The thermal conductance is approximately 2.4 nW/K and the thermal conductivity is nearly 3500 W/m/K at room temperature for a SWNT of length 2.6 um and diameter 1.7 nm. A subtle decrease in thermal conductivity steeper than 1/T is observed at the upper end of the temperature range, which is attributed to second order three-phonon scattering between two acoustic modes and one optical mode. We discuss sources of uncertainty and propose a simple analytical model for the SWNT thermal conductivity including length and temperature dependence.Comment: Nano Letters, vol. 6, no. 1, 200