Elaine DiMasi

Brookhaven National Laboratory, New York City, New York, United States

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Publications (69)230.37 Total impact

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    ABSTRACT: Systematic changes in the exocyclic substiution of core phthalocyanine platform tune the absorption properties to yield commercially viable dyes that function as the primary light absorbers in organic bulk heterojunction solar cells. Blends of these complementary phthalocyanines absorb a broader portion of the solar spectrum compared to a single dye, thereby increasing solar cell performance. We correlate grazing incidence small angle x-ray scattering structural data with solar cell performance to elucidate the role of nanomorphology of active layers composed of blends of phthalocyanines and a fullerene derivative. A highly reproducible device architecture is used to assure accuracy and is relevant to films for solar windows in urban settings. We demonstrate that the number and structure of the exocyclic motifs dictate phase formation, hierarchical organization, and nanostructure, thus can be employed to tailor active layer morphology to enhance exciton dissociation and charge collection efficiencies in the photovoltaic devices. These studies reveal that disordered films make better solar cells, short alkanes increase the optical density of the active layer, and branched alkanes inhibit unproductive homogeneous molecular alignment.
    Journal of Materials Chemistry A: Materials for Energy and Sustainability 02/2013; 1(5):1557-1565.
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    ABSTRACT: We report the synthesis and nanostructural development of polycrystalline and single crystalline LiFePO4 (LFP) nanostructures using a solvothermal media (i.e., water–tri(ethylene glycol) mixture). Crystal phase and growth behavior were monitored by powder and synchrotron X-ray diffraction, as well as transmission electron microscopy (TEM), while particle morphologies were examined using scanning electron microscopy (SEM). Initially, thin (100 nm) platelets of Fe3(PO4)2·8H2O (vivianite, VTE) formed at short reaction times followed by the nucleation of LFP (20 nm particles) on the metastable VTE surfaces. Upon decrease in pH, primary LFP nanocrystals subsequently aggregated into polycrystalline diamond-like particles via an oriented attachment (OA). With increasing reaction time, the solution pH further decreased, leading to a dissolution–recrystallization process (i.e., Ostwald ripening, OR) of the oriented polycrystalline LFP particles to yield evenly sized, single crystalline LiFePO4. Samples prepared at short reaction durations demonstrated a larger discharge capacity at higher rates compared with the single crystalline particles. This is due to the small size of the primary crystallites within larger secondary LiFePO4 particles, which reduced the lithium ion diffusion path while subsequently maintaining a high tap density. Understanding the relationship between solution conditions and nanostructural development as well as performance revealed by this study will help to develop synthetic guidelines to enable efficient lithium ion battery performance.
    Crystal Growth & Design 01/2013; 13(11):4659-4666. · 4.69 Impact Factor
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    ABSTRACT: During mineralization, the hard outer magnetite-containing shell of the radular teeth of Cryptochiton stelleri undergoes four distinct stages of structural and phase transformations: (i) the formation of a crystalline α-chitin organic matrix that forms the structural framework of the non-mineralized teeth, (ii) the templated synthesis of ferrihydrite crystal aggregates along these organic fibers, (iii) subsequent solid state phase transformation from ferrihydrite to magnetite, and (iv) progressive magnetite crystal growth to form continuous parallel rods within the mature teeth. The underlying α-chitin organic matrix appears to influence magnetite crystal aggregate density and the diameter and curvature of the resulting rods, both of which likely play critical roles in determining the local mechanical properties of the mature radular teeth.
    Advanced Functional Materials 01/2013; 23:2908-2917. · 10.44 Impact Factor
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    ABSTRACT: Collagen in vertebrate animals is often arranged in alternating lamellae or in bundles of aligned fibrils which are designed to withstand in vivo mechanical loads. The formation of these organized structures is thought to result from a complex, large-area integration of individual cell motion and locally-controlled synthesis of fibrillar arrays via cell-surface fibripositors (direct matrix printing). The difficulty of reproducing such a process in vitro has prevented tissue engineers from constructing clinically useful load-bearing connective tissue directly from collagen. However, we and others have taken the view that long-range organizational information is potentially encoded into the structure of the collagen molecule itself, allowing the control of fibril organization to extend far from cell (or bounding) surfaces. We here demonstrate a simple, fast, cell-free method capable of producing highly-organized, anistropic collagen fibrillar lamellae de novo which persist over relatively long-distances (tens to hundreds of microns). Our approach to nanoscale organizational control takes advantage of the intrinsic physiochemical properties of collagen molecules by inducing collagen association through molecular crowding and geometric confinement. To mimic biological tissues which comprise planar, aligned collagen lamellae (e.g. cornea, lamellar bone or annulus fibrosus), type I collagen was confined to a thin, planar geometry, concentrated through molecular crowding and polymerized. The resulting fibrillar lamellae show a striking resemblance to native load-bearing lamellae in that the fibrils are small, generally aligned in the plane of the confining space and change direction en masse throughout the thickness of the construct. The process of organizational control is consistent with embryonic development where the bounded planar cell sheets produced by fibroblasts suggest a similar confinement/concentration strategy. Such a simple approach to nanoscale organizational control of structure not only makes de novo tissue engineering a possibility, but also suggests a clearer pathway to organization for fibroblasts than direct matrix printing.
    Biomaterials 07/2012; 33(30):7366-74. · 8.31 Impact Factor
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    ABSTRACT: Nature has evolved efficient strategies to synthesize complex mineralized structures that exhibit exceptional damage tolerance. One such example is found in the hypermineralized hammer-like dactyl clubs of the stomatopods, a group of highly aggressive marine crustaceans. The dactyl clubs from one species, Odontodactylus scyllarus, exhibit an impressive set of characteristics adapted for surviving high-velocity impacts on the heavily mineralized prey on which they feed. Consisting of a multiphase composite of oriented crystalline hydroxyapatite and amorphous calcium phosphate and carbonate, in conjunction with a highly expanded helicoidal organization of the fibrillar chitinous organic matrix, these structures display several effective lines of defense against catastrophic failure during repetitive high-energy loading events.
    Science 06/2012; 336(6086):1275-80. · 31.20 Impact Factor
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    ABSTRACT: We have investigated the effects of moderate static magnetic fields (SMFs) on murine MC3T3-E1 osteoblasts, and found that they enhance proliferations and promote differentiation. The increase in proliferation rates in response to SMFs was greater in cultures grown on partially sulfonated polytstyrene (SPS, degree of sulfonation: 33%) than in cultures grown on tissue culture plastic. We have previously shown that when the degree of sulfonation exceeded a critical value (12%) [1], spontaneous fibrillogenesis occured which allowed for direct observation of the ECM fibrillar organization under the influence of external fields. We found that the ECM produced in cultures grown on the SPS in the presence of the SMFs assembled into a lattice with larger dimensions than the ECM of the cultures grown in the absence of SMFs. During the early stages of the biomineralization process (day 7), the SMF exposed cultures also templated mineral deposition more rapidly than the control cultures. The rapid response is attributed to orientation of diamagnetic ECM proteins already present in the serum, which could then initiate further cellular signaling. SMFs also influenced late stage osteoblast differentiation as measured by the increased rate of osteocalcin secretion and gene expression beginning 15 days after SFM exposure. This correlated with a large increase in mineral deposition, and in cell modulus. GIXD and EDXS analysis confirmed early deposition of crystalline hydroxyapatite. Previous studies on the effects of moderate SMF had focused on cellular gene and protein expression, but did not consider the organization of the ECM fibers. Our ability to form these fibers has allowed us explore this additional effect and highlight its significance in the initiation of the biomineralization process.
    Biomaterials 11/2011; 32(31):7831-8. · 8.31 Impact Factor
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    ABSTRACT: Bone is a hierarchically structured composite which imparts it with unique mechanical properties and bioresorptive potential. These properties are primarily influenced by the underlying nanostructure of bone, which consists of nanocrystals of hydroxyapatite embedded and uniaxially aligned within collagen fibrils. There is also a small fraction of non-collagenous proteins in bone, and these are thought to play an important role in bone's formation. In our in vitro model system of bone formation, polyanionic peptides are used to mimic the role of the non-collagenous proteins. In our prior studies, we have shown that intrafibrillar mineralization can be achieved in synthetic reconstituted collagen sponges using a polymer-induced liquid-precursor (PILP) mineralization process. This led to a nanostructured arrangement of hydroxyapatite crystals within the individual fibrils which closely mimics that of bone. This report demonstrates that biogenic collagen scaffolds obtained from turkey tendon, which consist of densely packed and oriented collagen fibrils, can also be mineralized by the PILP process. Synchrotron X-ray diffraction studies show that the mineralization process leads to a high degree of crystallographic orientation at the macroscale, thus emulating that found in the biological system of naturally mineralizing turkey tendon.
    CrystEngComm 03/2011; 13(6). · 3.88 Impact Factor
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    ABSTRACT: All-conjugated block copolymers have significant potential for solution-processed optoelectronic applications, in particular those relying on a p/n junction. Herein, we report the synthesis and structure of all-conjugated diblock copolymers poly(3-hexylthiophene)-block-poly(9,9-dioctylfluorene) and poly(3-hexylthiophene)-block-poly(9,9-dioctylfluorene-co-benzothiadiazole) in thin films and in the bulk. The diblock copolymers are prepared using a combination of Grignard metathesis polymerization and Suzuki polycondensation and characterized with NMR spectroscopy, size-exclusion chromatography, multiangle laser light scattering, and UV/vis spectroscopy. Structure in thin films and in the bulk is characterized using differential scanning calorimetry, X-ray diffraction, small-angle X-ray scattering, and atomic force microscopy. Diblock copolymer thin films self-assemble into a crystalline nanostructure with some long-range order after extended solvent annealing, and X-ray scattering measurements show that powder samples exhibit crystallinity throughout the bulk. By temperature dependent X-ray scattering measurements, we find that diblock copolymers self-assemble into crystalline nanowires with phase segregated block copolymer domains. These measurements show all-conjugated diblock copolymers may be useful for achieving solution-processed active layers in organic photovoltaics and light-emitting diodes with optimized structural and photophysical characteristics.
    Macromolecules 01/2011; 44(3). · 5.93 Impact Factor
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    ABSTRACT: The extracellular matrix (ECM) is composed of mixed protein fibers whose precise composition affects biomineralization. New methods are needed to probe the interactions of these proteins with calcium phosphate mineral and with each other. Here we follow calcium phosphate mineralization on protein fibers self-assembled in vitro from solutions of fibronectin, elastin and their mixture. We probe the surface morphology and mechanical properties of the protein fibers during the early stages. The development of mineral crystals on the protein matrices is also investigated. In physiological mineralization solution, the elastic modulus of the fibers in the fibronectin-elastin mixture increases to a greater extent than that of the fibers from either pure protein. In the presence of fibronectin, longer exposure in the mineral solution leads to the formation of amorphous calcium phosphate particles templated along the self-assembled fibers, while elastin fibers only collect calcium without any mineral observed during early stage. TEM images confirm that small needle-shape crystals are confined inside elastin fibers which suppress the release of mineral outside the fibers during late stage, while hydroxyapatite crystals form when fibronectin is present. These results demonstrate complementary actions of the two ECM proteins fibronectin and elastin to collect cations and template mineral, respectively.
    Journal of Structural Biology 04/2010; 170(1):83-92. · 3.36 Impact Factor
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    ABSTRACT: The details of air nanobubble trapping at the interface between water and a nanostructured hydrophobic silicon surface are investigated using X-ray scattering and contact angle measurements. Large-area silicon surfaces containing hexagonally packed, 20 nm wide hydrophobic cavities provide ideal model surfaces for studying the morphology of air nanobubbles trapped inside cavities and its dependence on the cavity depth. Transmission small-angle X-ray scattering measurements show stable trapping of air inside the cavities with a partial water penetration of 5-10 nm into the pores, independent of their large depth variation. This behavior is explained by consideration of capillary effects and the cavity geometry. For parabolic cavities, the liquid can reach a thermodynamically stable configuration-a nearly planar nanobubble meniscus-by partially penetrating into the pores. This microscopic information correlates very well with the macroscopic surface wetting behavior.
    Nano Letters 02/2010; 10(4):1354-8. · 13.03 Impact Factor
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    ABSTRACT: Recent analyses of the ultrastructural and mechanical properties of mineralized biological materials have demonstrated some common architectural features that can help explain their observed damage tolerance. Nature has accomplished this feat through the precise control of anisotropic crystal nucleation and growth processes in conjunction with nanoscale control over the self-assembly of spatially distinct organic and inorganic phases, resulting in effective inhibition of crack propagation through these materials. One such example is found in the hyper-mineralized and abrasion resistant radular teeth of the chitons, a group of herbivorous marine mollusks who have the surprising capacity to erode away the rocky substrates on which they graze. Through the use of modern microscopy and nanomechanical characterization techniques, we describe the architectural and mechanical properties of the radular teeth from Cryptochiton stelleri. Chiton teeth are shown to exhibit the largest hardness and stiffness of any biominerals reported to date, being notably as much as three-fold harder than human enamel and the calcium carbonate-based shells of mollusks. We explain how the unique multi-phasic design of these materials contributes not only to their functionality, but also highlights some interesting design principles that might be applied to the fabrication of synthetic composites.
    Materials Today 01/2010; 13(1):42-52. · 6.07 Impact Factor
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    ABSTRACT: Liquid crystal (LC) elastomers with bent-core side-groups incorporate the properties of bent-core liquid crystals in a flexible and self-supporting polymer network. Bent-core liquid crystal elastomers (BCEs) with uniform alignment were prepared by attaching a reactive bent-core LC to poly(hydrogenmethylsiloxane) and crosslinking with a divinyl crosslinker. Phase behavior studies indicate a nematic phase over a wide temperature range that approaches room temperature, and thermoelastic measurements show that these BCEs can reversibly change their length by more than a factor of two upon heating and cooling. Small-angle X-ray scattering studies reveal multiple, broad low-angle peaks consistent with short-range smectic C order of the bent-core side groups. A comparison of these patterns with predictions of a Landau model for short-range smectic C order shows that the length scale for smectic ordering in BCEs is similar to that seen in pure bent-core LCs. The combination of rubber elasticity and smectic ordering of the bent-core side groups suggests that BCEs may be promising materials for sensing, actuating, and other advanced applications.
    Journal of Materials Chemistry 01/2010; 20(39). · 5.97 Impact Factor
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    ABSTRACT: Small angle X-ray diffraction from the uniaxial nematic phase of certain bent-core liquid crystals is shown to be consistent with the presence of molecular clusters possessing short-range tilted smectic (smectic-C) order. Persistence of these clusters throughout the nematic phase, and even into the isotropic state, likely accounts for the unusual macroscopic behavior previously reported in bent-core nematics, including an anomalously large flexoelectric effect ( 1000 times that of conventional calamitic nematics), very large orientational and flow viscosities ( 10–100 and 100–1000 times, respectively, typical values for calamitics), and an extraordinary flow birefringence observed in the isotropic state.
    Soft Matter 01/2010; · 4.15 Impact Factor
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    ABSTRACT: The field-induced transitions between ferri-, antiferro-, and ferroelectric liquid crystal phases are interesting because although there are only small thermodynamic differences between them, each of these phases has different electrical and optical properties. We report an irreversible field-induced transition from an antiferroelectric phase to the ferrielectric phase in a liquid crystal device, and compare it to a system in which the transition is reversible. The two systems differ mainly in their spontaneous polarization (120 nC cm−2 for the former and 60 nC cm−2 for the latter) while the optical tilt is comparable (29° and 25°, respectively). We explain the observed transitions based on the relative magnitudes of the discrete flexoelectric and spontaneous polarizations.
    Applied Physics Letters 04/2009; 94(15):153507-153507-3. · 3.79 Impact Factor
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    ABSTRACT: Electrospinning of polymeric fibers has been attracted increased interest in recent years. However, the research for ethylene-vinyl acetate (EVA) and linear polyethylene (PE) is still limited, due to their relatively poor solubility in conventional solvent systems at ambient temperature. In this study, EVA and PE fibers were electrospun with different fiber diameter when the electrospinning solution was kept at a temperature greater than that of the solidification temperature of the polymer solutions. The effects of the fiber physical dimension to its crystallization and mechanical properties were thus detected. The morphology of the fibers was measured by scanning electron microscope (SEM) and atomic force microscope (AFM). The shear modulation force microscopy technique (SMFM) was used to measure the melting point, Tm, which was found to increase with increased fiber diameter and crystallinity. AFM three-point bending test demonstrated that the Young's modulus of the fibers drastically increased as fiber diameter decreased.Grazing-incidence small angle x-ray scattering (GISAX) showed that, compared to the bulk material, the crystallinity of the electrospun fibers had been changed.
    03/2009;
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    ABSTRACT: Little is known about the role of various ECM proteins in the formation of calcium phosphate during the biomineralization. Here we follow the calcium phosphate mineralization process in vitro using two different ECM proteins, fibronectin and elastin. The mechanical properties of the protein fibers during the early stages were probed by shear modulation force microscopy. The development of the mineral crystals along the protein matrices was investigated by scanning electron microscopy, soft x-ray scanning transmission microspectroscopy, and grazing-incidence synchrotron x-ray diffraction. The elastic modulus of the fibers in the elastin-fibronectin mixture increased to a greater extent than that of the fibers from a single protein. In the presence of fibronectin, longer exposure in the mineral solutions led to the formation of hydroxyapatite crystals templated along the self-assembled fiber structures, while elastin fibers collected calcium without crystallizing. Ca L-edge XANES spectra confirm that Ca in the Ca-elastin complex lacks the mineral anion coordination found in the fibronectin systems and in Ca mineral controls.
    03/2009;
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    ABSTRACT: X-ray absorption fine structure spectroscopy has been used to study the chemical and structural properties of self-forming diffusion barrier layers from Cu-8 at. % Mn alloy films on porous low-k and thermally grown SiO2 dielectrics. For the porous low-k/Cu(Mn) system, we provide evidence that the interface is composed of MnSiO3 and MnO with near complete Mn segregation from the alloy film; however, we find that the self-forming process does not go to full completion on thermally grown SiO2 substrates.
    Applied Physics Letters 01/2009; 94(4):042112-042112-3. · 3.79 Impact Factor
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    ABSTRACT: Understanding how biomineralization occurs in the extracellular matrix (ECM) of bone cells is crucial to the understanding of bone formation and the development of a successfully engineered bone tissue scaffold. It is still unclear how ECM mechanical properties affect protein-mineral interactions in early stages of bone mineralization. We investigated the longitudinal mineralization properties of MC3T3-E1 cells and the elastic modulus of their ECM using shear modulation force microscopy, synchrotron grazing incidence X-ray diffraction (GIXD), scanning electron microscopy, energy dispersive X-ray spectroscopy, and confocal laser scanning microscopy (CLSM). The elastic modulus of the ECM fibers underwent significant changes for the mineralizing cells, which were not observed in the nonmineralizing cells. On substrates conducive to ECM network production, the elastic modulus of mineralizing cells increased at time points corresponding to mineral production, whereas that of the nonmineralizing cells did not vary over time. The presence of hydroxyapatite in mineralizing cells and the absence thereof in the nonmineralizing ones were confirmed by GIXD, and CLSM showed that a restructuring of actin occurred only for mineral-producing cells. These results show that the correct and complete development of the ECM network is required for osteoblasts to mineralize. This in turn requires a suitably prepared synthetic substrate for bone development to succeed in vitro.
    Tissue Engineering Part A 09/2008; 15(2):355-66. · 4.07 Impact Factor
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    ABSTRACT: Liquid crystals are intriguing electrically responsive soft matter systems. We report previously unexplored field-induced changes in the structures of some frustrated liquid crystal phases and describe them theoretically. Specifically, we have discovered using resonant x-ray scattering that the four-layer intermediate smectic phase can undergo either a transition to the ferrielectric (three-layer) phase or to the ferroelectric phase, depending on temperature. Our studies of intermediate phases using electric fields offer a way to test theories that describe ferroelectricity in self-assembling fluids.
    Physical Review E 02/2008; 77(1 Pt 1):010701. · 2.31 Impact Factor
  • Key Engineering Materials - KEY ENG MAT. 01/2008;

Publication Stats

617 Citations
230.37 Total Impact Points

Institutions

  • 1997–2013
    • Brookhaven National Laboratory
      • Physics Department
      New York City, New York, United States
  • 2002–2012
    • Harvard University
      • • Wyss Institute for Biologically Inspired Engineering
      • • Department of Physics
      Cambridge, MA, United States
  • 2010
    • Stony Brook University
      • Department of Materials Science and Engineering
      Stony Brook, NY, United States
  • 2007–2008
    • The University of Manchester
      • School of Physics and Astronomy
      Manchester, ENG, United Kingdom
  • 2005
    • Norwegian University of Science and Technology
      • Department of Physics
      Trondheim, Sor-Trondelag Fylke, Norway
  • 2004
    • Bar Ilan University
      • Department of Physics
      Ramat Gan, Tel Aviv, Israel