Photosystem I Incorporation into Metal Organic Frameworks for Advanced Bio-hybrid Photoactive Materials

Metal-organic frameworks (MOFs) are a new type of hybrid material with unique properties that allow for diverse functionality and have shown promise for use in gas storage and separation, catalysis, chemical sensors, supercapacitors, drug delivery, and proton conduction in membranes for fuel cells. Metal ion nodes are connected by organic struts to create infinite crystalline porous networks with tunable geometries and chemical functionalities that have led to more than 20,000 different MOF structures reported in the past decade. These lattices have uniform pore sizes that can range from 0.4 to 10 nm and have set new records for free volume and internal surface area. MOFs offer unique advantages as a porous material over purely inorganic crystallines, such as zeolites, and purely organic aerogels or polymers. The atomic positions of the lattice can be known at the sub-angstrom level, determined almost exclusively by the coordination geometry of the metal node and the topology of the organic linker. Additionally, the chemical composition of the structure can be altered one functional group at a time via pre- or post-synthetic modification of the linkers. This leads to the ability to finely control both the geometry and chemistry of the MOFs; as form begets function, all mechanical, chemical, optical, and electrical properties can be rationally tuned. The vast majority of research on MOFs has centered around their microporosity. The ability to create very small, uniform pores potentially allows for more efficient means of gas and liquid separation. Because this is a new material, the idea of optimizing the already exceptional properties of MOFs is appealing. Due the immense number of possible combinations of metal nodes and organic linkers, there is indication that they hold true promise for utilization in electronic and optoelectronic devices. We have proposed and executed a new method for embedding, protecting, and activating the Photosystem I protein complex inside the ZIF-8 framework

Detotaliseerimine ja tagasiulatuv jõud: musta püramiidi semiootika

Väitekirja üldiseks probleemiks on semiootika integreeritavus. Detotalisatsioon kirjeldab semiootikatraditsiooni, mille kohaselt suletud terviklikkus pole võimalik, ning mis oma põhiliste teoreetiliste koordinaatidena näeb psühhoanalüüsi, ideoloogia kriitikat ja strukturaalset semioloogiat. Oluliseks analüüsivahendiks on autori poolt välja töötatud nn “musta püramiidi” skeem-mudel, mille abil otsitakse vastust küsimusele: kuidas saab puhtdiferentsiaalne, erinevustel põhinev (internaalne) süsteem suhestuda välisega (eksternaalsega)? Järgnevalt jõutakse semiootikas esineva subjektiivse relativismi kriitikani ja võetakse kasutusele retroaktiivsuse mõiste, mille kaudu kirjeldatakse väliseid mõjusid. Semiootika osavaldu vaadeldakse retroaktiivsuse toimimise aspektist. “Musta püramiidi” skeem-mudel ühendab hübriidselt Peirce’i ja Hjelmslev’ semiootikat, integreerides Peirce’i detotalisatsiooniga. Skeem eristab märgifunktsiooni ja märgiproduktsiooni ala ning selle jaotuse kaudu sulandab Peirce’i trihhotoomia kokku Saussure’i dihhotoomiaga. Taolisel sünteesil on kaks eelist. Esmalt on detotalisatsiooni subjektivistlik relativism ankurdatud kognitiivsemiootika ja biosemiootika empiiriliste ja loogiliste rakenduste poolt. Teisalt on kognitiivsemiootika ja biosemiootika rikastatud retroaktiivsuse tekstiliste protseduuridega, mis võimaldab ligipääsu välisele ilma märgi määratlust kahjustamata. Seeläbi on olemas artikulatoorse alusmaatriksi teaduslik seletus, kuid samuti vajadus teaduslikus semiootikas detotalisatsioonile iseloomuliku tekstuaalse eksperimenteerimise järele. Just retroaktiivsus on see ühendav mõiste, mis seob kaks semiootika lahusolevat valda. Integreerides ka kognitiivsemiootika ja biosemiootika detotaliseeritud semiootika pildile, pakub väitekiri kokkuvõttes mittereduktiivse ja empiirilise vastuse relativismi probleemile semiootikas, säilitades seejuures semiootika teoreetilise terviklikkuse ja pakkudes välja ühtse metakeele killustatud sotsiaalteaduste tarbeks.  Detotalization describes the tradition of semiotics which takes psychoanalysis, ideology critique, and structural semiology as its major theoretic coordinates. Interest in these coordinates has declined against the ascent of the semiotics of Charles Peirce, the two approaches are sometimes construed as irreconcilable, but the dissertation seeks to integrate Peirce to the coordinates of detotalization. This integration requires that Peirce be read in the way that Jacques Derrida and Umberto Eco propose to read him, by moderating his realism. This is achieved through theorization of the notion of retroactivity. Chapters one through four restate the coordinates of detotalization in terms of retroactivity, and chapter five searches the domains of cognitive and biosemiotics for the Peircean equivalent of retroactivity. The black pyramid schema is a picture of the Peirce-Hjelmslev hybrid, where Peirce is integrated to detotalization. In the schema, semiotics is organized by the domains of sign function and sign production, and the Peircean trichotomy is reconciled to the Saussurean dichotomy by means of this division. The synthesis has two advantages. In one direction, the subjectivist relativism of detotalization is anchored by the empirical and logical applications of cognitive and biosemiotics. In the other direction, cognitive and biosemiotics are enhanced by the textual procedures of retroactivity, which account for the external without compromising the definition of the sign by importing a naïve referent. There is a scientific explanation for the profound articulatory matrix, but there is also a need within scientific semiotics for the textual experimentation characteristic of detotalization. Retroactivity as the bridge concept between the two divided camps of semiotics also restores its original ambition, to provide a unifying vocabulary for the fractured social sciences.https://www.ester.ee/record=b540146

Synthesis and Mechanical Properties of Metallic Multilayers

Compositionally modulated alloys and artificial superlattices are thin-layered structures where the layer thickness is on the order of a few 10s of lattice constants. These alloys have been shown to be unusually strong. Their overall thickness can be very large, in this study we have grown these to a thickness of 45 µm by 2.5 cm, in diameter, much greater than the average. We posit the reasons for this strength are that, during deformation, glissile dislocations are pinned at layer boundaries, the presence of image forces, and the formation of Lomer-Cottrell and Hirth dislocation locks. In this thesis we examine the fundamental reasons why layered alloys show such as high yield stress and compare our experimental data with our strength model using compositionally modulated copper-nickel as an example. We combine experimental synthesis with the molecular dynamics modelling using LAMMPS to compare this data with first principle modelling. LAMMPS shows dislocations pinning at alternate boundaries, consistent with literature observations. The consequences of this work bears directly on the fields of electrical contacts, sliding wear, and even enhancement of bulk materials strength. We have found that Cu-Ni compositionally modulated alloys can exhibit a hardness of over 500 Hv which corresponds to breaking stresses over 1.5 GPa. We have not observed a significant systematic modulus enhancement. We show that is it possible to produce these compositionally modulated alloys directly on copper coated silicon by electrodeposition through a mask to yield strong materials that can have consequences for new kinds of technological advances in integrated circuit processing that can be integrated into existing manufacturing methods. Because electrochemical deposition is widely used in the field of contacts, these results can have almost immediate practical application in this field. Electrodeposition is also an ambient temperature process, so interfaces can be made very compositionally sharp allowing components mounted on adjacent circuits to remain thermally undamaged. Using this process, it is possible to electrochemically place extremely strong metals anywhere on conductive substrate at essentially ambient temperature

The semiotic life cycle and The Symbolic Species

In The Symbolic Species (1997) Terrence Deacon identifies human verbal language acquisition as the first and foremost evolutionary threshold where symbol use happens, with all the concomitant adaptive advantages it affords, but along with these advantages in this book and elsewhere he alludes to certain disadvantages that result from symbols. To describe these disadvantages he uses words like maladaptation, parasitism, cognitive penumbra, and other hyperbolic terms. He does so offhandedly, either in connection with the results of some laboratory experiments, or simply in disconnected ominous generalizations, but never justifies these sign effects within the dominantly Peircean model of language acquisition that gives the book its title. In later works Deacon attempts to contextualize these generalizations within Richard Dawkins’ theory of the meme. Deacon is sometimes disparaged for his supposedly imprecise or incorrect use of the sign theory of Charles Peirce to defend his claims about memes and symbols. The problem is not that Peirce should not be used in this way. In fact Deacon’s book is a singular achievement in the application of Peirce. The problem is that Deacon’s Peircean model is too simple. In fact Deacon’s claim about the possible disadvantages of symbol use can be reinforced with a closer look at the mature, turn-of-the-century Peircean sign model. This preserves the theoretical integrity of The Symbolic Species and clarifies the relation between memes and signs

Design and optimization of a long travel, two-axis flexural nanopositioning stage

This thesis details the design, computational optimization, and resultant evaluation of a two-axis flexural nanopositioning stage based on a modified version of a double parallelogram flexure which features underconstraint-eliminating features nested within the flexural bearing. The stage was optimized using a response surface model with the seven most sensitive geometric parameters for the flexural bearing as inputs, and the flexure’s peak stress and reaction force at maximum deflection as outputs. This paper shows that—through design optimization—the first resonant mode of a long travel, two-axis flexural nanopositioning stage that has previously been reported in literature can be improved by a factor of two while still maintaining the higher-order resonant modes to be at least an order-of-magnitude higher than the fundamental mode of the stage. This improvement is critical because increasing the fundamental mode without sacrificing the higher order modes will allow for a higher bandwidth controller to be implemented on this nanopositioning stage. The end goal of the positioning stage detailed in this paper is to be implemented within a micro-SLS 3D printer.Mechanical Engineerin

The Synthesis and Characterization of Iron Nanoparticles

Nanoparticle synthesis has garnered attention for technological applications for catalysts, industrial processing, and medical applications. The size ranges for these is in the particles nanostructural domain. Pure iron nanoparticles have been of particular interest for their reactivity and relative biological inertness. Applications include cancer treatment and carrying medicine to a relevant site. Unfortunately, because of their reactivity, pure iron nanoparticles have been difficult to study. This is because of their accelerated tendency to form oxides in air, due to the increased surface area to volume ratio. Using synthesis processes with polyphenols or long chain amines, air stable iron nanoparticles have been produced with a diameter size range of ~ 2 to about ~10 nm, but apparently have transformed due to internal pressure and crystallographic defects to the FCC phase. The FCC crystals have been seen to form icosahedral and decahedral shapes. This size is within the range for use as a catalyst for the growth of both carbon nanotubes and boron nitride nanotubes as well for biomedical applications. The advantages of these kinds of catalysts are that nanotube growth can be for the first time separated from the catalyst formation. Additionally, the catalyst size can be preselected for a certain size nanotube to grow. In summary: (1) we found the size distributions of nanoparticles for various synthesis processes, (2) we discovered the right size range for growth of nanotubes from the iron nanoparticles, (3) the nanoparticles are under a very high internal pressure, (4) the nanoparticles are in the FCC phase, (5) they appear to be in icosahedral and decahedral structures, (6) they undergo room temperature twinning, (7) the FCC crystals are distorted due to carbon in octahedral sites, (8) the iron nanoparticles are stable in air, (9) adding small amounts of copper make the iron nanoparticles smaller

Against aspiration

A short piece on the adoption of the political rhetoric of 'aspiration' by the left in contemporary British politics, for a report published by the think tank, the Centre for Labour and Social Studie

Development of Cellulose Nanofiber Reinforced Poly(Methyl Methacrylate)

Cellulose nanofiber (CNF), derived from renewable resources, is a good candidate to reinforce transparent plastics without sacrificing their transparency, owing to its size on the nano-meter scale, reflective index similar to the plastics’, excellent mechanical property, and low density. This study investigates effects of CNF on optical, viscoelastic, and thermal properties of CNF reinforced poly(methyl methacrylate) (PMMA). CNF/PMMA with different CNF contents and different types of PMMA were prepared through a solvent casting method with a low toxic and inexpensive solvent, acetone, and compression-molded to create nanocomposite films. The films were characterized using a transmission electron microscope, ultraviolet–visible (UV-Vis) spectrophotometry, dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). It was found that CNFs were well-dispersed in the PMMA matrix and the viscoelastic and thermal properties of the PMMA were increased by the addition of CNF, while maintaining a high degree of transparency and increasing attenuation capability of ultraviolet light