bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design, Synthesis and Characterization of New Bimechanistic Optical Power Limiters Based on Reverse Saturable and Two-photon Absorption
Authors: Spangler C. W. , Elandaloussi E. H. , Ozer B. , Ashworth K. , Madrigal L. , Reeves B. 
Published: April 2011

AbstractDuring the past five years there has been considerable progress in the design of organic materials for optical power limiting (OPL) applications. One of the more promising and widely studied material approaches involves reverse saturable absorption (RSA) from various excited states. We have recently been examining the efficacy of utilizing highly absorbing photogenerated charge states for RSA. Both polaronic radical cations and bipolaronic dications are possible candidates for this mode of optical limiting. Equally intriguing are new approaches to designing chromophores with large two-photon absorption (TPA) cross-sections. For some pulse durations the effective two-photon cross-section for bis-(diphenylamino)diphenylpolyenes, and dendrimers based on these repeat units, are extraordinaryly large, indicative of excited state absorption. In this presentation we will discuss the possibility of combining these two optical limiting mechanistic paradigms in single structures, which may then be considered as bimechanistic optical power limiters.
Optical Limiting With Neutral Nickel Dithiolene Complexes
Authors: Tan W. L. , Ji W. , Zuo J. L. , Bai J. F. , You X. Z. , Lim J. H. , Yang S. S. , Hagan D. J. , Stryland E. W. Van 
Published: April 2011

AbstractWe report an investigation of optical-limiting behavior in two neutral nickel complexes with multi-sulfur 1,2 dithiolene ligands, [Ni(medt)2] I (medt = 5,6-dihydro-6-methyl-1,4-dithiin-2,3- dithiolate) and [Ni(phdt)2] 2 (phdt = 5,6-dihydro-5-phenyl-l,4-dithiin-2,3-dithiolate) in benzene solution. The fluence-dependent transmission of the complexes was observed with nanosecond and picosecond laser pulses at 532-nm wavelength. The limiting thresholds of the complexes were ˜0.3 J/cm2, when measured with the picosecond pulses. Both picosecond time-resolved pump-probe and Z-scan measurement revealed that the limiting effects should originate from excited-state absorption and refraction. The transparency window (400˜900 nm), observed in the linear absorption spectra of the complexes, indicated that their limiting response should cover a wider range than those of fullerenes and phthalocyanines.
Photo-Induced Effects in Mn4+:YAG. Observation of Unusually Efficient Excited State Absorption and a Long–Lived Metastable State
Authors: Han Yanong , Spangler Lee H. , Hutcheson Ralph , Equall Randy W. 
Published: April 2011

AbstractThe Mn4+ ion has the same d3 electron configuration as Cr3+, but is less stable and can transform to other valence states. Both ions are known to occupy several sites in garnet hosts, giving rise to rather complicated optical spectra and photo-induced phenomena. Here, the spectra of the transient, photo-induced absorption and the emission of Mn4+,:YAG are analyzed over a broad wavelength region (from 450 to 1200nm) and over a wide range of time scales (from ns to minutes). Very large amplitude and extremely broadband excited state absorption are observed. Additionally, a long lifetime, photo-induced species was detected that is likely formed via charge transfer. The demonstrated behavior of this material shows it has potential applications for optical limiting and optical storage.
Optical Limiters: Spatial, Temporal, and Bio-Optical Effects
Authors: Hollins R C , McEwan K J , Till S J , Lund D J , Zuclich J A 
Published: April 2011

AbstractThis paper examines the goals which a nonlinear limiter must achieve in order to protect an eye against injury by a pulsed laser. The shape and temporal structure of the image presented to the retina are discussed. New bio-optical data describing retinal injury thresholds for largeimage sources are used to estimate the ocular hazard. The issues and trade-offs surrounding the incorporation of a limiter into an optical system are examined, and the suitability of different materials for an effective low-loss limiter are compared.
A Novel Method For Solution Deposition of Hydroxyapatite on to Three Dimensionally Porous Metallic Surfaces: Peri-Apatite Ha
Authors: Zitelli Joseph P. , Higham Paul 
Published: April 2011

AbstractA method for applying HA coatings to metallic surfaces, without the use of high temperature plasma spraying, has been developed. The HA coating is precipitated in an aqueous solution under conditions similar to those occurring in the body during bone formation. This surface mineralization process results in a coating which is highly crystalline and 100% HA. Processing and characterization experimentation and results are included in the paper.The coating method has the ability to penetrate macroporous (> 100 micron pores) metal structures and coat the undersides and interior surfaces of the areas designed for bone ingrowth on orthopedic devices used for joint replacements. This ability to coat all around a surface is the basis for the name Peri-Apatite HA. Electron microscopy is presented illustrating the coverage and morphology of the coating.The Peri-Apatite HA coating is currently used on both knee joint replacement and hip joint replacement implants.
Apatite Formation on Electrochemically Treated Titanium
Authors: Tsuru K. , Takemoto S. , Hayakawa S. , Osaka A. 
Published: April 2011

AbstractApatite formation on artificial materials in a body environment is the prerequisite condition for showing bioactivity i.e. bone-bonding ability. A specific hydrated silica or titania gel has the ability of apatite deposition in body environment. We electrochemically prepared such a bioactive titanium oxide layer on titanium(Ti) with a cell consisting of Ti as the working electrode, Pt as the counter one, Ag/AgCl as the reference one, and an aqueous solution of 0.1 mol/L Ca(NO3)2 as the electrolyte solution. Ti was kept at 9.5V for 1 hour for oxidation(denoted as Ca9.5). Ti was subject to cathodic polarization at −3.0V for 10 min(Ca-3.0).: calcium ions were expected to be adsorbed on its surface. On treatment Ca9.5–3.0 Ti was first oxidated at 9.5V for 1 hour and subsequently kept at −3.0V for 10 min. The specimens of Ca9.5–3.0 and Ca-3.0 were found so bioactive as to deposit apatite within 12 hours and 1 day, respectively, in a simulated body fluid(Kokubo solution) whereas those due to Ca9.5 could not deposit apatite within 7 days. Calcium hydroxide and calcium carbonate detected on the bioactive surface caused no harmful effects on spontaneous deposition of apatite in the fluid.
Template-Mediated Biomineralization of Hemozoin
Authors: Wright David W. , Ziegler James 
Published: April 2011

AbstractA critical target for the development of new antimalarial treatments is the detoxification pathway of free heme released during the catabolism of host hemoglobin in the digestive vacuole of the malaria parasite Plasmodium falciparum. We have synthesized and examined two peptide dendrimers (BNT I and II) based on the tandem repeat motif of HRP II from P. falciparum for their abilities to both bind heme substrates and to form the critical detoxification polymer hemozoin. Each substrate was capable of binding significant amounts of the natural substrate Fe(III)PPIX along with other substrates such as Zn(II)PPIX and the metal free PPIX. Further, it was shown that the dendrimeric BNT I and II were capable of supporting the aggregation of hemozoin and that this process could be inhibited by the known antimalarial drug, chloroquine.
Importance of Electrostatic Interactions Between Calcite Surfaces and Proteins
Authors: Rodripuez-Navarro Aleiandro , Messier Russell , Jimenez-Lopez Concepcion , Garcia-Ruiz Juan Manuel 
Published: April 2011

AbstractWe have studied the electrostatic interactions of proteins with the calcite surfaces during its subsequent nucleation and growth on a surface. In doing so, a model system of four globular proteins (lysozyme, ribonuclease, myoglobin and α-lactalbumin), having the same size and conformation, but differing in surface properties (i.e. surface charge) was used. Depending on the nature of the charge on the protein, its morphological effect on calcite growth (inhibition of specific crystal faces) varies, with this effect becoming more pronounced as the protein is more negatively charged. To study how the adsorption of proteins affects the growth of calcite along different crystal directions, calcite plates cut with different crystallographic orientations (i.e. (001), (104), (100) and (110)) were used as substrates. The overgrowing calcite crystals show the same orientation as the substrate. The nucleation density also varies with the crystallographic orientation of the calcite substrates, increasing in accordance with the sequence: (110), (100) and (001). Finally, to study how the protein itself controls the orientation of crystals, we used amorphous substrates (glass). After incubation on the glass substrates with negatively charged proteins, an oriented nucleation of the calcite crystals was induced.
Spectroscopic Studies of Manganese Doped LaGaO3 Crystals
Authors: Noginov M. A. , Noginova N. , Loutts G. B. , Babalola K. , Rakhimov R. R. 
Published: April 2011

AbstractWe have grown Mn:LaGaO3 crystals (Mn=0.5%, 2%, 10%, and 50%) and studied their properties with the methods of optical and EPR spectroscopy. We have found Mn2+, Mn4+, and Mn5+ ions in low doped crystals (Mn=0.5% and 2%) and Mn3+ ions in crystals with higher Mn concentrations (10% and 50%). The formation of Mn3+ valence state in Mn:LaGaO3 is discussed.
Giant 1/f Noise in Low-Tc CMR Manganites: Evidence of the Percolation Threshold
Authors: Podzorov V. , Uehara M. , Gershenson M. E. , Koo T. Y. , Cheong S-W. 
Published: April 2011

AbstractWe observed a dramatic peak in the 1/f noise at the metal-insulator transition (MIT) in low-Tc, manganites. This many-orders-of-magnitude noise enhancement is observed for both polycrystalline and single-crystal samples of La5/8−y. Pry, Ca3/8MnO3 (y = 0.35 – 0.4) and Pr1−xCaxMnO3 (x = 0.35 – 0.5). This observation strongly suggests that the microscopic phase separation in the low-Tc, manganites causes formation of a percolation network, and that the observed MIT is a percolation threshold. It is shown that the scale of phase separation in polycrystalline samples is much smaller than that in single crystals.
Spectroscopic Studies of Inhomogeneous Electronic Phases in Colossal Magnetoresistance and Charge-Ordering Compounds
Authors: Cooper S. L. , Liu H. L. , Yoon S. , Cheong S-W. , Fisk Z. 
Published: April 2011

AbstractInfrared reflectance and Raman spectroscopy measurements have been performed through the metal-semiconductor (or -semimetal) transitions of various “colossal magnetoresistance” and charge-ordering materials, including EuB6 and the manganese perovskites. As described in this paper, our results demonstrate that these systems have phase regions characterized by electronic inhomogeneity of various types, including: (1) pure spin polarons, which form in a narrow temperature range above Tc in the “colossal magnetoresistance” system EuB6; (2) magnetoelastic polarons, and an inhomogeneous ferromagnetic phase comprised of both metallic and insulating regions, in the “colossal magnetoresistance” regime of La1−x(Sr,Ca)xMnO3 (x < 0.5); and (3) phase separation behavior involving coexisting ferromagnetic and antiferromagnetic domains in the intermediatetemperature (CO) phase of the charge-ordering system Bi1−xCaxMnO3 (x > 0.5).
Critical Phenomena at the Antiferromagnetic Transition in MnO
Authors: Woodfield B.F. , Shapiro J.L. , Stevens R. , Boerio-Goates J. , Wilson M.L. 
Published: April 2011

AbstractThe specific heat of a polycrystalline sample of MnO was measured from T ≈ 1 K to T ≈ 400 K using two different experimental apparatuses at zero applied pressure. Features revealed by the data include a hyperfine contribution due to the Mn nuclei, a T2 temperature dependence at low temperatures due to the type-II antiferromagnetic magnon contribution, and a sharp but well defined antiferromagnetic transition (TN = 117.7095 K) that is clearly second order in nature. The critical exponent, α, deduced from the transition is consistent with a two dimensional Ising model. The specific heat of MnO is also compared with recent results on the type-A antiferromagnet LaMnO3.
Tunnel Type Magnetoresistance in Electron Beam Deposited Films of Compositions (Co0.5Fe0.5)x(Al2O3)(100-x) (7 ≤ x ≤ 52)
Authors: Khan H.R. , Vovk A. Ya , Kravets A.F. , Shipil O.V. , Pogoriliy A.N. 
Published: April 2011

AbstractA series of 400 nm thick metal-insulator films of compositions (Co50Fe50)x(Al2O3(100-x) (7 ≤ x ≤ 52; x is in vol.%) are deposited on glass substrates using dual electron beam evaporation technique. The films are nanocrystalline with crystallite sizes of 1-3 nm. Resistivity of the films varies as a function of (I/T)0.5 showing a tunneling type behaviour. The films show isotropic and negative magnetoresistance (GMR). A film of composition (Co50Fe50)82.5(Al2O3)17.5 show maximum tunneling magnetoresistance (TMR) of 7.2% at room temperature and in a magnetic field of 8.2 kOe.
Structure and Magnetism of Nanocrystalline KδMnO2
Authors: Stroud R.M. , Carpenter E. , Browning V.M. , Long J.W. , Swider K.E. , Rolison D.R. 
Published: April 2011

AbstractThe structure and magnetic properties of sol-gel-synthesized, nanocrystalline KσMnO2 were investigated. The nanoparticles were determined by x-ray diffraction and high-resolution transmission electron microscopy to be single-crystal rods of the cryptomelane phase of MnO2, with a typical particle size of 6 nm × 20 nm. The field and temperature dependence of the magnetization indicates superparamagnetic behavior, with a blocking temperature of 15K. The dependence of the magnetic properties on particle size, surface layers and mixed valency is discussed.
Discovery of a High Spin Freezing Temperature and Control of a Spin-Glass State in Mg1.5FeTi0.5O4 Spinel Films
Authors: Muraoka Y. , Tabata H. , Kawai T. 
Published: April 2011

AbstractA spin-glass state up to 210 K has been found in (Mg,Fe){Mg,Fe,Ti)2O4 spinel ferrite thin films formed on α-Al2O3(0001) substrates. The long-time relaxation of the magnetization in zero-field-cooled operation, which is characteristic feature of the spin-glass state, has been observed below 210 K. We have also achieved the change of magnetic state in the film from spin-glass to ferrimagnet over a wide temperature range below 160 K by means of light-irradiation. The amount of spin-melt on light-irradiation is calculated to be 41 % at 10 K and 26 % at 100 K.
Deposition and Electrical Characterization of Dielectric/Ferromagnetic Heterostructure
Authors: Wu T. , Ogale S.B. , Garrison J.E. , Nagaraj B. , Chen Z. , Ramesh R. , Venkatesan T. 
Published: April 2011

AbstractWe grow Pb(Zr,Ti)O3 (001)/La1−xCaxMnO3 (001) hetereostructure epitaxially on Nb doped STO substrate using pulsed laser ablation. A field effect device configuration is formed with the manganite as the channel and the Nb:STO substrate as the gate. Channel resistance modulation by the gate pulsing is studied both with and without magnetic field. We not only find a remarkably large electroresistance effect of 76% at 4× 105V/ cm, but also the complimentarity of this ER effect with the widely studied CMR effect. The large size of this effect and the complimentarity of ER and MR effects strongly suggest a percolative phase separated picture of manganites.
Epitaxial Pb(Zr0.52Ti0.48)O3/La0.7(Pb,Sr)0.3MnO3 Ferroelectric/CMR Memory Optimized for Room Temperature Operation
Authors: Lundström Daniel , Yilbar Jan , Khartsev S.I. , Grishin Alex , Okuyama Masanori 
Published: April 2011

AbstractEpitaxial ferroelectric/colossal magnetoresistive PbZr0.52Ti0.48O3/La0.7(Pb,Sr)0.3MnO3 (PZT/LPSMO) thin film heterostructures have been grown onto SrTiO3 single crystals by KrF pulsed laser deposition technique to fabricate nonvolatile magnetosensitive memory. Colossal magnetoresisitivity (CMR) in LPSMO film has been tailored to room temperature by compositional control to get the maximum temperature coefficient of resistivity of 7.3 %K−1 @ 295 K and maximim magnetoresistivity of 27% @ 7 kOe and 300 K. The main processing parameters have been optimized to preserve CMR performance in LPSMO film after deposition of the top ferroelectric layer. Vertical Au/PZT/LPSMO/STO capacitor cell possesses very high dielectric permittivity about 1500 and rather low loss of 5% at 1 kHz, saturation polarization of 40.4 µC/cm2, remnant polarization of 20.6 µC/cm2, coercive field of 22.8 kV/cm, and no visible fatigue after 1.33.108 reversals. Three top contact metals: Au, Pt, and Ta, deposited at room temperature, have been examined. As compared with Ta, Pt and Au top contacts show superior performance regarding to combined properties: high remnant and saturation polarization, low loss and no fatigue while top Ta contacts have been found to be more efficient to reduce leakage in ferroelectric film.
Synthesis and Properties of Epitaxial Thin Films of c-axis Oriented Metastable Four-Layered Hexagonal BaRuO3
Authors: Lee M. K. , Eom C. B. , Tian W. , Pan X. Q. , Smoak M. C. , Tsui F. , Krajewski J. J. 
Published: April 2011

AbstractWe have grown epitaxial thin films of metastable four-layered hexagonal (4H) BaRuO3 on (111) SrTiO3 by 90° off-axis sputtering techniques. X-ray diffraction and transmission electron microscopy experiments reveal that the films are single crystals of c-axis 4H structures with an inplane epitaxial arrangement of BaRuO3 [2110] // SrTiO3 [110]. Smooth multilayer growth has been observed in these films with a step height equaling the size of half unit cell. In-plane resistivity of the films is metallic, with a room temperature value of about 810µΩ-cm and slightly curved temperature dependence. Their magnetic susceptibility is paramagnetic. The metastable layered compounds can be very useful for understanding new solid-state phenomena and novel device applications.
Growth and Characterization of Epitaxial Thin Heterostructures of Ferromagnetic/Antiferromagnetic SrRuO3/Sr2YRuO6
Authors: Price R.A. , Lee M.K. , Eom C.B. , Wu X.W. , Rzchowski M.S. 
Published: April 2011

AbstractWe have grown epitaxial thin films of antiferromagnetic ruthenate Sr2YRuO6 on miscut (001) SrTiO3 by 90° off-axis sputtering. Sr2YRuO6 is a unique material that allows us to grow epitaxial ferromagnetic/antiferromagnetic heterostructures. Antiferromagnetic Sr2YRuO6 has the same pseudo-cubic perovskite crystal structure as the ferromagnetic conductive oxide SrRuO3. The Sr2YRuO6 perovskite crystal structure has Y and pentavalent Ru located on the octahedral sites and the pseudo-cubic lattice parameter of 4.08Å. The Neel temperature of bulk Sr2YRuO6 is known to be 26K. Four-circle X-ray diffraction analysis revealed the Sr2YRuO6 films are purely (110) normal to the substrate with two 90° domains in the plane. We have also grown epitaxial heterostructures of SrRuO3/Sr2YRuO6. These bilayers permit detailed studies of the magnetic exchange bias phenomena at these interfaces, including the role of uncompensated spins thought to arise from interface roughness. Magnetization measurements on the SrRuO3/Sr2YRuO6 heterostructures show a shifting of the hysteresis loop, indicating exchange bias. Such exchange-biased interfaces are important for electrode pinning in magnetic tunnel junctions.
Substituted Barium Hexaferrite Films for Planar Integrated Phase Shifters
Authors: Oliver S.A. , Yoon S.D. , Kozulin I. , Shi P. , Zuo X. , Vittoria C. 
Published: April 2011

AbstractThick films of scandium-substituted BaScxFe12−xO19 (x=0, 0.4, 0.6) were deposited by pulsed laser ablation deposition onto A-plane (1120) sapphire (Al2O3) substrates to yield highly oriented films having the crystallographic c-axis ([0001]) in the film plane. Selected films were characterized by x-ray diffraction, electron microscopy, magnetometry and torque magnetometry measurements. These structural and magnetic measurements show that dense films have excellent in-plane uniaxial anisotropies and good square loop behaviors. Such films will be useful for planar latched phase shifters that can be integrated into microwave integrated circuits.
Properties of Zr-Substituted (Ba,Sr)TiO3 Thin Films for Integrated Capacitors
Authors: Stauf G. T. , Chen P. S. , Paw W. , Roeder J. F. , Ayguavives T. , Maria J.-P. , Kingon A. I. 
Published: April 2011

AbstractThere has been significant interest recently in use of BaSrTiO3 (BST) thin films for integrated capacitors; these devices have benefits for high frequency operations, particularly when high levels of charge or energy storage are required. We discuss the electrical properties of BST thin films grown by metalorganic chemical vapor deposition (MOCVD) which make them suitable for these applications, as well as the impact of processing conditions such as growth temperature on specific film properties. We have also examined addition of Zr in amounts ranging up to 20% to the BST films. X-Ray diffraction indicates that the Zr is incorporated into the BST lattice. Voltage withstanding capability, leakage and dielectric constant of the thin films have been measured as functions of deposition temperature and Zr content. Addition of Zr to BST films increases breakdown voltages by as much as a factor of two, to approximately 2 MV/cm, raising their energy storage density values to levels approaching 30 J/cc. Charge storage densities of above 60 fF/µm2were also obtained.
Pulsed Laser Deposited Na0.5K0.5NbO3 Thin Films
Authors: Cho Choong-Rae , Grishin Alex , Moon Byung-Moo 
Published: April 2011

AbstractNa0.5K0.5NbO3 films have been grown onto polycrystalline Pt80Ir20 substrates at two different regimes: high (∼ 400 mTorr) and low (∼ 10 mTorr) oxygen pressure. Films grown at high oxygen pressure have been found to be single phase and highly c-axis oriented. The concept of discriminated thermalization has been developed to explain the dynamics of the laser ablation process and to find reliable pulsed laser deposition (PLD) processing conditions. The phenomenon of self assembling of Na0.5K0.5NbO3 films along [001] direction has been observed. On the other hand, films grown at low oxygen pressure have been found to be mixed phase of ferroelectric Na0.5K0.5 NbO3 and paraelectric potassium niobates. Superparaelectric behavior has been observed in these films: 5% tunability at electric field of 100 kV/cm, losses as low as 0.003 and excellent stability to the temperature and frequency changes.
Dielectric Properties of Ba1−xSxTiO3 Films Grown on LaAlO3 Substrates
Authors: Gim Y. , Hudson T. , Fan Y. , Findikoglu A. T. , Kwon C. , Gibbons B. J. , Jia Q. X. 
Published: April 2011

AbstractWe report the crystal structures and dielectric properties of barium strontium titanate, Ba1−xSrxTiO3 (BST), films deposited on LaAlO3 substrates using pulsed laser deposition, where x = 0.1 to 0.9 at an interval of 0.1. We have found that when x < 0.4 the c-axis is parallel to the plane of the substrate but normal as x approaches 1. Temperature-dependent capacitance measurements at 1 MHz show that the capacitance has a peak and that the peak temperature decreases with increasing x. We have found that the peak temperatures of the films are about 70 °C higher than those of bulk BSTs when x < 0.4. From room-temperature capacitance (C) vs applied voltage (V) measurements, we have found that the C-V curves of the BST films exhibit hysteresis except for x = 0.9 and that the peak voltage at which the capacitance becomes maximum decreases with increasing x. At room temperature, the Ba0.6Sr0.4 TiO3 film exhibits the largest capacitance tunability (≈ 37%) with an applied electric field of 40 kV/cm.