1,228 research outputs found
Using imaging ToF-SIMS data to determine the cell wall thickness of fibers in wood
No full textHere, we demonstrate the use of time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging data for estimation of cell wall thickness in wood samples. Current research in forest biotechnology focuses on transgenic trees with wood properties tailored to specific applications. Appropriate analytical methods to characterize the very heterogeneous wood material are constantly being developed and improved. Chemical imaging of wood by ToF-SIMS represents an interesting tool for this purpose with many applications. In addition to wood chemistry, the impact of specific genetic modifications on wood anatomy needs to be assessed. Cell wall thickness is an important anatomical parameter that among others is used for assessing biomass accumulation. We developed a strategy to estimate cell wall thickness from ToF-SIMS images and implemented it in the open source programming language R'. In brief, random lines are projected over the black and white mask of a ToF-SIMS image, and length values of all line sections that cut across a cell wall are collected. After enough iteration, the shortest values of the obtained count distribution represent the crossing sections normal to the cell walls, hence cell wall thickness. Compared with conventional light microscopy image analysis, TOF-SIMS data offers many advantages such as submicron resolution and additional spectral information for automated annotation of distinct anatomical features. This work underlines the importance of SIMS imaging for studies of wood chemistry and anatomy and provides a new approach to obtain an important wood anatomical parameter from ToF-SIMS data
'A bright memory to remain' : the life and works of Charles Sims RA (1873-1928)
No full textThis thesis investigates the life and work of the English painter Charles Sims RA (1873-1928). It takes the form of a monograph and examines key themes of Sims' career within a chronological framework. The study makes consistent reference to the Sims Archive — the artist's studio contents recently brought to light by the author in negotiation with the artist's family and currently in the possession of Northumbria University. For the first time Sims' working practices and motivations have been explored in detail, thus contributing to knowledge of this particular neglected painter and more generally allowing some additional insight into the problems besetting and opportunities afforded to British artists of his generation. Sims' career spanned a transitional period in British art history which is currently being reassessed by art historians: the debates surrounding the effects of European modernism on British art, the inevitable impact of the Great War and the search during the 1920s for a visual language appropriate to modern life. Sims negotiated disparate experiences and preoccupations in an interesting way, and produced a stylistically diverse body of work in his continued search, I argue, for an alternative to modern reality. He attempted the combination of ancient religions, past art and modern experience into pictorial idylls that were simultaneously familiar and unattainable. The thesis aims to explore Sims' inspiration and reassesses his career within the context of his better known contemporaries by cross-referencing information held in national and international collections, libraries and archives with the hitherto unseen material here
Adolescent inhalant abuse results in adrenal dysfunction and a hypermetabolic phenotype with persistent growth impairments
No full textAbstract not availableRose Crossin, Zane B. Andrews, Natalie A. Sims, Terence Pang, Michael Mathai, Jonathan H. Gooi, Aneta Stefanidis, Brian J. Oldfield, Andrew J. Lawrence, Jhodie R. Dunca
Synthesis of furanosesquiterpenoid natural products
No full textThe effect of addition of a catalytic quantity of a crown ether in the reaction of a phosphonate anion with a carbonyl compound (Wadsworth-Emmons reaction) has been studied and found to greatly facilitate this reaction. This modification of the Wadsworth-Emmons reaction, using a catalytic amount of 15-crown-5, has been employed in the synthesis of the naturally occurring furanosesquiterpene Pallescensin-E. The structure of this compound has been confirmed by comparison of its spectral data with that of the synthesised isomer, 4,l0-dihydro-7,8-dimethyl 10H-benzof4,5Jcycloheptafl,2-bJ furan.Homosesquirosefuran, an analogue of the naturally occurring furanosesquiterpene Sesquirosefuran, has been synthesised via the dianion of methylacetoacetate.An approach to the synthesis of Pinguisone (a component of the essential oil of the liverwort Aneura pinguis)has been attempted employing two Diels-Alder reactions to generate the four cis-methyl groups found in the natural product.In a study of the reaction of n-(2-methylallyl)nickel bromide complex with a range of epoxides, this complex was found not only to react with reactive epoxides (e.g. styrene epoxide) but also with less reactive propylene epoxide.Substrates for possible intramolecular n-allylnickel cyclisation to generate an a-methylene-6-valerolactone ring system have been prepared
Structural Effects in 2D-Stabilized FAPbI3 Films and ToF-SIMS for Ultra-thin h-BN Fabrication
No full textThe next generation of electronics, photonics, and optoelectronics are based on advancements in semiconductor materials. In such, it is vital to gain understanding of and cultivate solutions for degradation pathways and engineer effective synthesis methods. This work details two thrusts that take a view through the stability and fabrication lens: first, structural changes in a novel method to stabilize halide perovskites, and second, a method for forming ultra-thin van der Waals materials.
Thrust I: The halide perovskite formamidinium lead iodide (FAPbI3) is a prime candidate for photovoltaics due to its excellent optoelectronic properties, but its application has been limited due to its structural instability. The large size of the FA cation results in metastability of the photoactive cubic phase and a facile degradation into the thermodynamically stable hexagonal phase at room temperature. Recently, the incorporation of 2D Ruddlesden-Popper halide perovskite seeds into a FAPbI3 precursor solution has been shown to template the growth of and stabilize cubic FAPbI3. Here, we investigate the nanoscale structural and optoelectronic mechanisms behind the observed
bulk stabilization using synchrotron-based x-ray microscopies. Nanoprobe x-ray diffraction reveals 2D-templated FAPbI3 films exhibit an average compressive strain normal to the substrate of -3.4%, two-fold larger than that of MACl-stabilized FAPbI3. Further, this compression creates locally templated regions comprised of tetragonal-phase FAPbI3 distributed non-uniformly throughout the film with fewer crystalline defects than purely cubic regions. Scanning x-ray excited optical luminescence (x-ray analogue of photoluminescence) reveals that this local templating results in increased radiative recombination and redshifted emission. Our results help better understand the structural phenomena resulting from stabilization methods in FAPbI3 for engineering durable photovoltaics.
Thrust II: In recent years, hexagonal boron nitride (h-BN) has become a promising candidate for next-generation electronics and photonics, such as a gate dielectric in field effect transistors. However, methods for fabrication of ultra-thin materials often lack spatial control or require harsh environment depositions. Here, we report a method to prepare ultra-thin h-BN using the combination of micromechanical cleaving (i.e. Scotch Tape Method) and ion beam etching through time-of-flight secondary ion mass spectrometry (ToF-SIMS). ToF-SIMS is further employed for 3D reconstruction of h-BN
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ToF-SIMS ion images of Messel fish fossil ganoid scale 2 (Fig 1C and 1D).
No full textA) Micrograph of ToF-SIMS analysis area on ganoid scale 2. High spatial resolution ToF-SIMS ion images of B) sum of porphyrin peaks (m/z 441, 455, 469 and 483) C) Fe+, D) FeC2N2-, E) Ni+, F) NiC2N2-, G) sum of PAHs (m/z 77, 91, 139, 141, 165), H) Al+, I) Si+, K) Mg+ and K) sum of AlSiO4- and AlSi2O6-. (PDF)</p
'A bright memory to remain' : the life and works of Charles Sims RA (1873-1928)
No full textThis thesis investigates the life and work of the English painter Charles Sims RA (1873-1928). It takes the form of a monograph and examines key themes of Sims' career within a chronological framework. The study makes consistent reference to the Sims Archive — the artist's studio contents recently brought to light by the author in negotiation with the artist's family and currently in the possession of Northumbria University. For the first time Sims' working practices and motivations have been explored in detail, thus contributing to knowledge of this particular neglected painter and more generally allowing some additional insight into the problems besetting and opportunities afforded to British artists of his generation. Sims' career spanned a transitional period in British art history which is currently being reassessed by art historians: the debates surrounding the effects of European modernism on British art, the inevitable impact of the Great War and the search during the 1920s for a visual language appropriate to modern life. Sims negotiated disparate experiences and preoccupations in an interesting way, and produced a stylistically diverse body of work in his continued search, I argue, for an alternative to modern reality. He attempted the combination of ancient religions, past art and modern experience into pictorial idylls that were simultaneously familiar and unattainable. The thesis aims to explore Sims' inspiration and reassesses his career within the context of his better known contemporaries by cross-referencing information held in national and international collections, libraries and archives with the hitherto unseen material here.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Supplemental Material - Longitudinal Patterns of Multimorbidity in Gulf War Era Veterans With and Without Gulf War Illness
No full textSupplemental Material for Longitudinal Patterns of Multimorbidity in Gulf War Era Veterans With and Without Gulf War Illness by Andrew D. Thompson, Sarah E. Petry, Elizabeth R. Hauser, Stephen H. Boyle, Gita A. Pathak, Julie Upchurch, Ashlyn Press, Melissa Johnson, Kellie J. Sims, Christina D. Williams, and Elizabeth J. Gifford in Journal of Aging and Health.</p
ToF-SIMS ion and SEM images of Messel fish fossil bone fragment (Fig 1E and 1F).
No full textA) Micrograph of ToF-SIMS analysis area on bone fragment. High spatial resolution ToF-SIMS ion images of B) sum of porphyrin peaks (m/z 441, 455, 469 and 483), C) Fe+, D) Ni+, E) sum of PAHs (m/z 77,91, 139, 141, 165), F) Al+, and G) Si+. H) SEM image of same area as in A. I) Zoom-in of area indicated by right white box in H where porphyrins were detected. J) Zoom-in of area indicated by white box in I with microbodies (white arrows). K) Zoom-in of area indicated by left white box in H with whitish non-bony structure (Fig 1E and 1F). L) Zoom-in of area indicated by white box in K showing fibrous structure (white arrow). (PDF)</p
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