bluuebunny/crossref_metadata_2025 huggingface dataset:
Hypophysitis secondary to nivolumab and pembrolizumab is a clinical entity distinct from ipilimumab-associated hypophysitis
Authors: Faje Alexander , Reynolds Kerry , Zubiri Leyre , Lawrence Donald , Cohen Justine V , Sullivan Ryan J , Nachtigall Lisa , Tritos Nicholas
Published: June 2019

Objective

Little has been published describing hypophysitis after nivolumab or pembrolizumab treatment. We aimed to (i) assess the risk of hypophysitis following nivolumab or pembrolizumab treatment, (ii) characterize the clinical presentation and outcomes in these patients and (iii) compare these patients to hypophysitis following ipilimumab and ipilimumab plus nivolumab (combo). We hypothesized that headaches, pituitary enlargement on MRI and multiple anterior pituitary hormone deficiencies would occur less often in the nivolumab/pembrolizumab group versus ipilimumab or combo hypophysitis patients.

Design and methods

We conducted a multi-center retrospective review utilizing the Research Patient Database registry to evaluate individuals diagnosed with hypophysitis following treatment with nivolumab/pembrolizumab (n = 22), ipilimumab (n = 64) and combo (n = 20). Encounter notes, radiologic imaging and laboratory results for these patients were comprehensively reviewed.

Results

Hypophysitis was rare following treatment with nivolumab/pembrolizumab (0.5%, 17/3522) compared to ipilimumab (13.6%, 34/250), P < 0.0001. Hypophysitis was diagnosed later in nivolumab/pembrolizumab (median: 25.8 weeks, interquartile range (IR): 18.4–44.0) compared to ipilimumab (9.3, IR: 7.2–11.1) or combo patients (12.5, IR: 7.4–18.6), P < 0.0001 for both. Headache and pituitary enlargement occurred less commonly in nivolumab/pemrolizumab patients (23% and 5/18, respectively) compared to ipilimumab (75%, 60/61) and combo (75%, 16/17) treatment groups (P < 0.0001 versus ipilimumab and P = 0.001 versus combo for headache and P < 0.0001 for both for enlargement).

Conclusions

This study represents the first comprehensive cohort analysis of nivolumab or pembrolizumab-associated hypophysitis in a large patient group. Hypophysitis occurs rarely with these medications, and these patients have a distinct phenotype compared to hypophysitis after treatment with ipilimumab or ipilimumab plus nivolumab.
Método de reducción de muestra para ensayos de laboratorio en mezcla asfáltica en caliente
Authors: Jiménez Acuña Mónica , Elizondo Arrieta Fabián
Published: June 2019

Para el año 2004 no se contaba con métodos de reducción de muestra para mezcla asfáltica en caliente estandarizados y se tomaban como referencia los métodos de cuarteo para agregados pero estos no indicaban obviamente la temperatura a la cual se debía calentar la muestra para asegurar su trabajabilidad y que no afectara las propiedades de la mezcla entre otros detalles. Es por esta razón que, el LanammeUCR implementó un método totalmente nuevo para poder certificar el muestreo de mezcla asfáltica en caliente en vagoneta, por lo que se aprovechó este estudio para incluir el método de cuarteo para demostrar que las submuestras son representativas del lote de muestra.

Se realizó un diseño experimental el cual incluía la realización del método de cuarteo para varias cajas de mezcla y luego medir la granulometría y el contenido de asfalto con el ensayo de ignición para cada submuestra así como el ensayo de gravedad específica máxima teórica, se demostró que con este método sí es posible obtener submuestras representativas del lote con buena repetibilidad y además se comprobó que la segregación de la mezcla se eliminó con el uso de la canaleta además de que se obtienen las submuestras deseadas en un solo paso.

Este método tiene 11 años de implementado y las ventajas sobre el método estándar AASHTO R 47 publicado en el año 2008 es que, en este método se detallan los cuidados que se tienen que tomar en cuenta a la hora de manipular la mezcla asfáltica en caliente, tales como las temperaturas a las que se tiene que calentar la muestra y los tiempos de calentamiento pues esto afecta de manera significativa las propiedades del material. Además se incluye el uso de herramientas manuales muy simples que son de fácil fabricación y económicas que tomaron en cuenta el criterio de ergonomía para asegurar que el procedimiento fuese seguro y práctico.
Hacia una construcción del sujeto en Michel Foucault
Authors: Gil Fernández Rosalía
Published: June 2019

Este artículo hace un recorrido por las obras de Michel Foucault que incursionan en la construcción de la subjetividad y su relación con el cuerpo humano. En Foucault esto se realiza a través de las ‘Tecnologías de Si,” que incluyen la inquietud y el cuidado de Sí, durante los períodos históricos que inician en tiempos greco-romanos y terminan en los albores de la modernidad.
Memorias del Trabajo Comunal Universitario en Promoción de la Salud Mental Costarricense
Authors: Rodríguez Gutiérrez Ana Lucía
Published: June 2019

En el presente artículo se expone a modo de ensayo las memorias del Trabajo Comunal Universitario realizado durante el año 2018 en promoción de la salud mental costarricense, con el fin de divulgar labores realizadas en espacios de salud como parte de la acción social universitaria (UCR). A modo de introducción, se presenta una revisión del marco teórico que fundamenta la promoción y prevención en salud mental, el contexto del sistema sanitario nacional y la descripción del TCU-505. En el ensayo se presentan las principales ideas sobre el trabajo realizado en los distintos espacios institucionales y extra-institucionales. Finalmente, se concluye a raíz de las labores realizadas la importancia de: (1) Fomentar redes de apoyo en el trabajo sanitario, (2) Llevar a cabo una planificación articulada a las condiciones particulares de la población meta, (3) La amplia demanda nacional en salud mental y (4) La aplicación de un enfoque bio-psico-social (interdisciplinariedad) en miras de promover una salud integral.
La importancia de las emociones para la neurodidáctica
Authors: Benavidez V Verónica , Flores P Ramón
Published: June 2019

Este artículo pretende exponer la importancia de las emociones para la neurodidáctica en la medida que éstas inciden en el proceso de aprendizaje. El objetivo de la neurodidáctica es potenciar el desarrollo de nuevas estrategias basadas en las teorías de las neurociencias, que dan cuenta del manejo de las emociones y su relación con el aprendizaje, mismo que se puede conceptualizar como la creación de memorias impulsadas por estímulos que lo potencian o inhiben. El aprendizaje tiene relación directa no solo con la memoria, sino fundamentalmente con los estímulos emocionales, de los que depende qué y con qué profundidad se aprende. El aprendizaje inicia en el hipocampo y amígdala, que colaboran en la evaluación de los estímulos emocionales. Las estrategias didácticas que se utilizan en el aula tienen la capacidad de favorecer el aprendizaje de los estudiantes o de impedirlo, en función de la gestión de las emociones que el maestro realice. El artículo se construyó sobre la base de la revisión de literatura relacionada con el funcionamiento del cerebro emocional, y la forma en que las emociones influyen en el aprendizaje humano.

Palabras clave: Neurociencias; neuroeducación; neurodidáctica; emociones
Detection of Paenibacillus larvae spores in honey by conventional PCR and its potential for American foulbrood control.
Authors: Rusenova N , Parvanov P. , Stanilova S.
Published: June 2019

The present study attempted to detect Paenibacillus larvae spores in naturally contaminated honeys by conventional PCR and to determine the sensitivity of the reaction with different primer pairs in order to assess its potential for American foulbrood control. For this purpose, duplicated honey samples were collected from 5 bee colonies with clinical American foulbrood and 5 clinically healthy colonies in the same apiary. The samples were analysed for the presence of Paenibacillus larvae spores by culture method and subsequent PCR detection in bacterial colonies. The PCR performed directly with spore DNA failed in 6 out of the 20 honeys investigated with spore load of 10–46 cfu/g. The established sensitivity of 70% of the reaction in the present study shows that the adequate control of American foulbrood by analysis of honeys for Paenibacillus larvae spore contamination should be done by combination of culture method followed by PCR in bacterial colonies, whose sensitivity was 100%.
Strong enhancement of 420∼425nm optical wavelength of blue LED by using CaF2 scintillating crystals as a cap
Authors: Nishimura Suzuka , Hirai Muneyuki , Nagayoshi Hiroshi , Terashima Kazutaka
Published: June 2019

It has been found that the blue light emission of LED is remarkably enhanced by using optical window of CaF2 disk doped with Eu2O3. The CaF2 crystals doped with Eu2O3 strongly absorb UV light with 330~420nm optical wavelength as a cutting filter. Instead, CaF2 crystals emit 420~425nm wavelength visible light. As a result, the UV light shifts to a light of around 420nm wavelength, and the LED light emission intensity markedly increases. In our experiments, the UV components were absorbed, while, around 420nm emitting light has been strengthened by more than 30%. The FWHM value is improved by around 30%.
Spectroscopic Imaging of Metal-Enhanced Upconversion on Plasmonic Substrates
Authors: Anderson R.B. , Fisher J. , Hor A. , Lu A. , Paudel H. , Bayat K. , Baroughi M. , Luk T-S. , May P.S. , Smith S.
Published: June 2019

We use spectroscopic imaging to investigate the enhancement of infra-red to visible upconversion in rare-earth doped nano-particles (NaYF4:Yb:Er) supported on nano-fabricated plasmonic substrates consisting of square lattices of Au nano-pillars fabricated by electron beam lithography and designed to support a surface plasmon polariton at frequencies which are nearresonant with the rare-earth ion (Yb3+) absorption. We observe a systematic enhancement in the efficiency of upconversion associated with the interaction of the co-doped nano-particles with the plasmonic substrate. Spectrally-resolved imaging provides a massively parallel means of assessing the range of achievable enhancement and its relation to the specific configuration of the substrate / upconverting nano-particle system. Spectrally-resolved reflectivity of the plasmonic substrates confirms the role of the surface plasmon polariton in the upconversion enhancement. Experimental results are compared to Finite Difference Time Domain simulations of the frequency-dependent reflectivity of these metallic nanostructures.
Non-woven Membranes Electrospun from Polylactic Acid Incorporating Silver Nanoparticles as Biocide
Authors: Vargas-Villagran Haydee , Teran-Salgado Elvia , Dominguez-Diaz Maraolina , Flores Osvaldo , Campillo Bernardo , Flores Araceli , Romo-Uribe Angel
Published: June 2019

In this research, we describe the electrospinning processing of polylactic acid (PLA) and the influence of silver nanoparticles on the morphology and microstructure of produced non woven membranes thus produced. The PLA was electrospun from a chloroform solution and a filamentary and granular morphology was obtained, the filaments having an average diameter of 1.25 μm, When silver nanoparticles (of ca. 12 nm size) were incorporated, the filaments diameter was reduced to an average of 0.65 μm, and the density of beads was also reduced. The membranes were rather amorphous, as revealed by X-ray scattering, presumably due to the quenching process associated with the electrospinning process. Water contact angle measurements showed that silver nanoparticles induced significant hidrophobicity in the membranes as neat PLA membrane had a contact angle of 54° and PLA/Ag membrane exhibited an angle of 115°.
Synthesis and Characterization of Silica-LiMn2O4Core-Shell Nanosphere Cathodes
Authors: Lee Jong-Moon , Hong Soon-Kie , Cho Won Il , Yeo In-Hyeong , Mho Sun-il
Published: June 2019

In order to improve the charge/discharge cycling performance of the LiMn2O4cathode, the spinel LiMn2O4is coated on the structurally stable SiO2nanosphere cores, LiMn2O4@SiO2. The core-shell LiMn2O4@SiO2nanosphere cathodes are prepared by the MnCO3precipitation on the silica surface and the following solid state reaction of MnCO3@SiO2with a lithium salt. The charge/discharge cycle stability has improved by the nanostructural characteristics of the LiMn2O4@ shell on the SiO2core. The cathode composed of LiMn2O4@SiO2nanospheres exhibits higher capacity retention of 97% than that of LiMn2O4nanoparticles of 89%, after 100 battery cycles at a 10C rate.
Silicon Quantum Dots-Carbon Nanotube Composite as Anode Material for Lithium Ion Battery
Authors: Zhong Lanlan , Xie Andi , Mangolini Lorenzo
Published: June 2019

Silicon is a very promising material for anodes of lithium ion batteries. It exhibits a high theoretical capacity of 3579 mAh/g. However, during the lithiation and de-lithiation, silicon materials experience up to a 300% volume change, leading to poor cyclability [1-2]. Research shows that reducing the silicon particle size can mitigate this problem. Carbon nanotubes (CNTs) function well as electrode materials in electrolytic cells because of their high electrical conductivity and surface area. In this work, we combine silicon nanoparticles (Si NPs) and CNTs as anode materials. Si NPs are generated using a plasma-enhanced chemical vapor deposition technique and their surface is modified with a 12-carbon long aliphatic chain to impart solubility in non-polar solvents. They are applied onto a nanotube-based layer using a wet-phase deposition technique. SEM and TEM analysis confirm that they form a conformal coating onto the nanotube surface. The CNTs - Si NPs composite active material is tested in half-cells where lithium foil acts as counter electrode. We have achieved an average of 810 mAh/g discharge capacity for composites with a CNTs to Si NPs weight ratio of 1:1. We expect to be able to increase the discharge capacity by increasing the Si NPs weight content.
High Efficiency Blue Organic Light Emitting Devices doped by BCzVBi in Hole and Electron Transport Layer
Authors: Kim Nam Ho , Kim You-Hyun , Yoon Ju-An , Lee Sang Youn , Yu Hyeong Hwa , Turak Ayse , Kim Woo Young
Published: June 2019

The electroluminescent characteristics of blue organic light-emitting diodes(BOLEDs) were fabricated with single emitting layer using host-dopant system and doped charge carrier transport layers. The structure of the high efficiency BOLED device was; NPB(600Å)/NPB:BCzVBi-7%(100Å)/ADN:BCzVBi-7%(300Å)/BAlq:BCzVBi-7%(100Å)/BAlq(200Å)/Liq(20Å)/Al(1200Å) to optimize probability of exciton generation by doping BCzVBi in emitting layer and hole/electron transport layers(HTL/ETL) as well. Luminance and luminous efficiency of BOLED doped BCzVBi in EML and HTL/ETL improved from 10090 cd/m2 at 9.5V and 6.44 cd/A at 4.0V to 13190 cd/m2 at 9.5V and 7.64 cd/A at 4.0V about 30% and 18%, respectively, with CIE coordinates of (0.14, 0.17) comparing to BOLED doped BCzVBi in EML only
Oxidation of Single-Crystal γ′-Ni3A1 at Low Oxygen Partial Pressure
Authors: Schumann E. , Schnotz G. , Salzberger U. , Rühle M.
Published: June 2019

Single crystals of γ′-Ni3Al((001)-oriented) were oxidized at 1223 K under an oxygen partial pressure of ∼4 ×10−19 atm for times ranging from 0.1 to 50 hours. Microstructural development of the oxide scale and subscale metal was studied by electron microscopy. A special technique permitted the reproducible and efficient preparation of TEM cross section specimens. Initially, a fine-grained γ-Al2O3 scale formed with a preferred orientation. Depletion of Al from the γ′-Ni3Al resultedin a Ni-Al solid solution zone between the oxide scale and the intermetallic. After 20 hours oxidation, a discontinuous α-A12O3 layer between the γ-A12O3 and the metal was observed. The α-A12O3 layer exhibited a much larger grain size than that of the γ-A12O3 and was continuous after 50 hours oxidation. Formation of the α-A12O3 layer correlated with a decreasing parabolic oxidation rate constant kp, as measured by thermogravimetric analysis (TGA).
The Microstructural Evolution of Nanometer Ruthenium Films in Ru/C Multilayers With Thermal Treatments
Authors: Nguyen Tai D. , Gronsky Ronald , Kortright Jeffrey B.
Published: June 2019

The evolution of nanometer Ru films sandwiched between various C layer thicknesses with thermal treatments was studied by plan-view and cross-sectional Transmission Electron Microscopy. Plan-view observation provides information on the Ru grain size, while crosssectional studies allow examination of the multilayer morphology. After annealing at 800°C for 30 minutes, the grain size in the 2 and 4 nm Ru layers show little difference from each other, while that in the I nm Ru layers depends strongly on the thickness of the C layers in the multilayers. It increases with decreasing C layer thickness. Agglomeration of the Ru layers is observed in Inmn Ru / 1nm C multilayers after annealing at 600°C for 30 minutes. The evolution of the microstructures and layered structure stability of the Ru/C system is compared to that of W/C and Ru/B4C systems.
Kinetics of Solid-State Reactions in Ni-Zr Thin Films
Authors: Schwarz R. B. , Rubin J. B.
Published: June 2019

We have studied the kinetics of the solid-state amorphizing reaction in thin film multilayers of Ni and Zr. Crystalline Ni and Zr films were deposited in ultra-high vacuum onto platinum resistance thermometers embedded in alumina. An electronic feedback circuit controls the temperature of the substrata by adjusting the power dissipated by the platinum resistors. We find that structural relaxation in the asdeposited Ni and Zr films affects the initial stages of the reaction. For long reaction times there is a discontinuous change in the reaction rate. The time to reach this transition increases with film thickness and depends exponentially on 1/T, with an apparent activation energy of 3 eV atom−1.
Heteroepitaxial Growth of MgO Films on NiO(100) Single Crystal Surfaces
Authors: Imaduddin S. , Davidson A.M. , Lad R.J.
Published: June 2019

Epitaxial MgO layers were grown on cleaved NiO(100) single crystal surfaces. The less than 1% lattice mismatch between MgO and NiO allows almost ideal epitaxy of MgO at 100°C. The epitaxial films were created by dosing Mg onto stoichiometric NiO(100) both in ultra-high vacuum (UHV) and in an O2 atmosphere (5×10−7 Torr). Chemical interactions at the resulting interfaces were studied using XPS. When Mg is dosed onto NiO(100) in UHV, MgO forms by interacting with oxygen anions in the NiO substrate thereby reducing the nickel cations. Metallic Mg layers begin to form upon subsequent dosing. When Mg is deposited in O2, epitaxial MgO(100) layers grow to a thickness of at least 50Å as confirmed by in situ RHEED and LEED observations. Negligible intermixing between the MgO and NiO is observed during growth at 100°C and on subsequent annealing in UHV up to 600°C.
Simulation of Desorption Kinetics at a Liquid-Solid Interface
Authors: Scott T. W.
Published: June 2019

Molecular dynamics simulations are reported for the atomic motion of adsorbates at a liquid-solid interface. The rate for physical desorption is analyzed using the potential of mean force to describe adsorbate and transition state energies.
The Initial Stages of Metal Deposition on Metal and Semiconductor Electrodes Studied byIn SituStm
Authors: Kolb D. M. , Randler R. J. , Wielgosz R. I. , Ziegler J. C.
Published: June 2019

The deposition of Cu onto Au(100) and of Pb onto n- Si(111) electrodes from aqueous solutions has been monitoredin situby scanning tunneling microscopy. In the first case, a bcc structure of the Cu overlayer is observed, which allows pseudomorphic growth on Au(100) up to the 10th layer. Then a slow structural transition to fee begins. In contrast, Pb on Si(111) is shown to deposit as 3D crystallites with flat (111) terminated surfaces.
In-Situ Characterization of the Surface State Density by Photoluminescence During Electrochemical Treatments of Silicon Surfaces
Authors: Dittrich T. , Timoshenko V. Y. , Rappich J.
Published: June 2019

The photoluminescence (PL) of c-Si is probed stroboscopically with single pulses of a N2 laser during electrochemical treatments (hydrogenation and anodic oxidation). The PL intensity of indirect semiconductors such as Si is controlled by the non-radiative surface and bulk recombination. By this reason the density of surface states can be estimated for unknown surfaces by using a calibrated standard. The surface state density of a hydrogenated Si surface increases by exchanging the electrolyte by gaseous N2 or water.
Fabrication and Characterization of Nife Thin Film Composition Modulated Alloys
Authors: Leith S. D. , Schwartz D. T.
Published: June 2019

Described are results showing that an oscillating flow-field can induce spatially periodic composition variations in electrodeposited NiFe films. Flow-induced NiFe composition modulated alloys (CMA's) were deposited on the disk of a rotating disk electrode by oscillating the disk rotation rate during galvanostatic plating. Deposit composition and structure were investigated using potentiostatic stripping voltammetry and scanning probe microscopy. Results illustrate a linear relationship between the composition modulation wavelength and the flow oscillation period. CMA's with wavelengths less than 10 nm can be fabricated when plating with a disk rotation rate oscillation period less than 3 seconds.
Heterojunctions in Nanowires by Electrochemical Processing
Authors: Redmond G. , Gilbert S. , Doudin B. , Ansermet J.-Ph.
Published: June 2019

Nanowires, 100 nm in diameter and 6 μm in length, with an oxide barrier intercalated between two ferromagnets, were produced via an electrochemical route. Non ohrnie behavior wa found. The magnetoresistance of Ni/NiO/Co heterostructures abruptly change by more than 7% at the switching field of the ferromagnets.
Electrodeposition of High-Tc Superconductor Material for Microsensor Fabrication
Authors: Natarajan A. , Wang W. , Ma E. , Bhattacharya R. N. , Khan-Malek C. , Paranthaman M. , Martin P. M.
Published: June 2019

Thin-films of YBa2Cu3O7 (YBCO) superconductor precursor were synthesized using an electrodeposition process. The YBCO precursor thin films were deposited on Ag foils using pulsed potential deposition conditions of 10 s at - 4 V and 10 s at -1 V (versus Ag reference electrode). The post-annealed films showed zero electrical resistance at 60 K. The procedures for the fabrication of a high precision micro-sensor using YBCO superconductor for measurement of weak magnetic fields are outlined. The micro-sensor templates were patterned using X-rays and precursor films were deposited into the features.
Electrochemical Study on the Growth of Multilayer Film Electrodes of the Conducting Polymers PPP, Pot and of the Copolymer of PPP and Pot
Authors: Kvarnström C. , Latonen R.-M. , Ivaska A.
Published: June 2019

Multilayer polymer film electrodes were prepared from the electrochemically synthesized conducting polymers poly(paraphenylene), PPP, poly(3-octylthiophene), POT and from the electrochemically synthesized copolymer of PPP and PO.T. The electrochemical behavior of the multilayer film electrodes made from PPP and POT is compared with the response of a copolymer layer. The structure of the copolymer film could be changed by varying the polymerization potential and the concentration as well as the ratio of the concentration of the two starting materials. Due to the slightly lower (0.15 V) oxidation potential of the POT monomer in comparison to the oxidation potential of biphenyl, POT is usually present to a higher extent than PPP in the electrochemically produced copolymer. The copolymer electrodes, the single polymer film layers and the multilayer polymer film electrodes showed different electrochemical response of the charging-discharging cycle.
Influence of Nucleation on the Crystallization Behavior of Electroless Nickel-Phosphorous Alloys
Authors: Oberie Robert
Published: June 2019

The production of amorphous electroless nickel (EN) deposits from hypophosphite (H2PO2−) containing solutions is well known. The crystallization of the deposits has been studied by differential scanning calorimetry (DSC) and the changes in crystallization behavior with deposit thickness have been attributed to chemical effects. In this work, DSC results from deposits initiated by use of a noble metal catalyst are compared to those from a conventional zincate.

The implication of the DSC data is that the bulk structure of the EN deposit is determined to a large degree by the mechanism of deposit initiation. This is in contrast to the conventional view that solution chemistry is the dominant factor that determines the properties of the deposit.
Investigation of the Codeposition of Polymer Lattices With Copper on a Rotating Disk Electrode
Authors: Fransaer J. , Celis J. P.
Published: June 2019

This article involves the study of the electrodeposition of composite coatings that form when colloidal particles deposit onto an electrode at which metal electrodeposition simultaneously occurs. The codeposition process of polystyrene (PS) and polymethylmethacrylate (PMMA) particles from a copper plating bath on a rotating disk electrode (rde) was investigated both theoretically and experimentally. The influence of the fluid flow velocity, density, mean size and zeta-potential of the particles, viscosity and temperature of the plating bath on the deposition rate of particles is studied using the theoretical model. The predictions of the model are compared with experimental results.
Etching of Polymers by Photo-Material Processing using an Excimer Lamp
Authors: Takezoe Noritaka , Yokotani Atsushi , Kurosawa Kou , Sasaki Wataru , Yoshida Kunio , Igarashi Tatsushi , Matsuno Hiromitsu
Published: June 2019

An excimer lamp is a new light source which can produce shorter wavelength of vacuum ultraviolet radiation than conventional ArF excimer lasers. We have tried to use the excimer lamp for photo-etching of polymers such as polymethylmetacrylie and polyimidic resins. We have found that the etching process was including the chemical and the quantumn processes. We also applied this technique for etching of some single crystalline organic materials which were very important to opt-electronic applications.
High Resolution Displacement of Functional Groups onto Fluorocarbon Resin Surface by Using ArF Excimer Laser
Authors: Shimizu T. , Murahara M.
Published: June 2019

A Fluorocarbon resin surface was selectively modified by irradiation with a ArF laser beam through a thin layer of NaAlO2, B(OH)3, or H2O solution to give a hydrophilic property. As a result, with low fluence, the surface was most effectively modified with the NaAlO2 solution among the three solutions. However, the contact angle in this case changed by 10 degrees as the fluence changed only 1mJ/cm2. When modifying a large area of the surface, high resolution displacement could not be achieved because the laser beam was not uniform in displacing functional groups. Thus, the laser fluence was successfully made uniform by homogenizing the laser beam; the functional groups were replaced on the fluorocarbon resin surface with high resolution, which was successfully modified to be hydrophilic by distributing the laser fluence uniformly.
Oxygen Vacancy Migration in Disordered Gd2(ZrxTi1-x)2O7
Authors: Williford R.E. , Weber W.J. , Devanathan R. , Gale J.D.
Published: June 2019

Oxygen vacancy formation and migration energies in the pyrochlores Gd2(ZrxTi1-x)2O7 were computed using atomistic energy minimization methods, with particular attention to the role of cation antisite disorder. The interatomic potentials recognize oxygens in distinct crystallographic sites (polarizations) as distinct species, and permit assessment of the directional anisotropy in vacancy migration energies. Oxygen vacancy migration is determined by O48f - O48f transitions along the shortest edges of the TiO6 octahedra, in agreement with previous results. Oxygen vacancies migrate towards disorder to reduce local stresses. In contrast to previous work, the VO8a and VO8a + IO8b Frenkel defects are favored over the VO8f and VO48f + IO8b Frenkel. The transition VO8a -> VO48f is energetically favored for the ordered structure, and activates the three dimensional O48f - O48f vacancy migration network by filling empty 8a sites with 48f oxygens. Local regions of order and moderate disorder must both be present for optimum oxygen conductivity. High disorder retards vacancy migration.
Open Resonator Technique for Measurement of Thin Dielectric Film Properties on Optically Dense Substrates
Authors: Dudorov Sergey , Lioubtchenko Dmitri , Mallat Juha , Tuovinen Jussi , Räisänen Antti V.
Published: June 2019

Thin dielectric films on the dielectric substrate are widely employed in millimeter and submillimeter wave device applications, so the problem of precise measurement of their properties is important. One of the most accurate technique for measurement of dielectric properties is the open resonator technique.

In this work we propose the method for measurements of thin dielectric film properties on the dielectric substrate using the open semispherical resonator. A good agreement (within 1 %) was obtained in refractive index data between results obtained with direct measurements and with proposed method for thin layer of SI GaAs on a sapphire substrate.
Subsurface Damage Profile Characterization of Si Wafers with Uv/Millimeter-Wave Technique and Light Scattering Topography
Authors: Katoh Takeo , Kondo Hideyuki , Ogita Yoh-Ichiro , Kobayashi Ken-Ichi , Kurokawa Masaki
Published: June 2019

We have characterized subsurface damage profiles of hydrogen-ion implanted silicon wafers by using a non-contact UV/Millimeter-Wave Technique and Light Scattering Topography (LST). A subsurface damage profile that was less than one micrometer was controlled by chemical mechanical polishing after hydrogen-ion implantation. On the area with the subsurface damage, the Photoconductivity Amplitude (PCA) signals measured by the UV/Millimeter-Wave Technique drastically weakened and the haze values measured by LST increased. A clear correlation has been found between the peak depth of the subsurface damage and the haze value. The spectral analyses of the surface images obtained by Atomic Force Microscopy (AFM) were carried out in order to separate the influences of surface micro roughness and subsurface damage on the haze value. The contribution of subsurface damage to the haze value can be formulated as the convolution of the damage profile and the transparency function of the incident laser in silicon crystal.
Isovalent Substitution of Sr for Ba in Ba3.75Nd9.5Ti18O54 Microwave Dielectric Ceramics – Experimental and Computer Modelling Studies
Authors: Setasuwon Paisan , Freer Robert , Azough Feridoon , Leach Colin
Published: June 2019

Ceramics of Ba3.75Nd9.5Ti18O54 substituted with 2, 5, 10, 20 and 50% Sr have been prepared by the mixed oxide route. Specimens were sintered at temperatures in the range 1350–1500°C. Densities were ∼95% theoretical. The solubility limit for Sr replacing Ba was found to be ∼10%. The relative permittivity (∼80) was almost independent of Sr content, but 2% Sr increased the Qxf value to a maximum of 11000. Static simulation of Sr- bearing Ba3.75Nd9.5Ti18O54 successfully reproduced the structure and lattice parameters to within 1–2%. Different site distributions of Ba-Sr ions have been explored.
BWO-Characterization of Materials and Devices at Frequencies 100-1000 GHz.
Authors: Volkov A. A. , Anzin V. B. , Goncharov Yu. G. , Gorshunov B. P. , Komandin G. A. , Spector I. E.
Published: June 2019

We have developed multipurpose spectral technique for amplitude and phase measurements at frequencies 100–1000 GHz based on the use of backward wave oscillators (BWOs) as sources of probing radiation. It utilizes to the utmost all the remarkable advantages of BWOs such as high radiation intensity, monochromaticity, polarization, as well as high speed and wide range of frequency tuning. Extremely simple and flexible open-space measurement geometries are used. The developed technique seems to be the most appropriate and promising for the reliable, precise and mass characterization of materials and devices at millimeter-submillimeter waves.
Hydrothermal Epitaxy of I:V Perovskite Thin Films
Authors: Goh Gregory K. L. , Donthu Suresh K.
Published: June 2019

Although epitaxial II:IV perovskite films like BaTiO3 and Pb(Zr,Ti)O3 have been grown by the hydrothermal method, there are hardly any reports on the growth of I:V perovskite thin films by this low temperature technique. In this study, thin films of NaNbO3, KTaO3 and KNbO3 were grown on (100) oriented single crystal SrTiO3 substrates by the hydrothermal method at 200°C and below. X-ray diffraction (XRD) revealed that the as-synthesized films were epitaxial with one of their original cubic axes normal to the substrate (100) plane. Scanning electron microscopy (SEM) showed that the films formed by an island growth mechanism. KTaO3 was also used as a buffer layer in the growth of KNbO3 films in order to investigate the effect of lattice mismatch on surface morphology and epitaxial quality, as determined by SEM and XRD rocking curve measurements, respectively.
Orientation-Dependent Dielectric Anomalies in Relaxor-Based Crystal (PbMg1/3Nb2/3O3)0.68(PbTiO3)0.32 (PMN-32%PT)
Authors: Tu Chi-Shun , Schmidt V. Hugo
Published: June 2019

Dielectric permittivities and polarization-electric-field (P-E) hysteresis loops have been measured as a function of temperature in relaxor-based ferroelectric single crystals (PbMg1/3Nb2/3O3)0.68(PbTiO3)0.32 (PMN-32%PT) for <110>cub and <211>cub orientations. Contrary to the pure PbMg1/3Nb2/3O3 (PMN), PMN-32%PT exhibits apparent orientation dependences of dielectric permittivities, polarizations, and phase transitions. With a prior fieldcooled treatment, a field-induced state, perhaps of orthorhombic symmetry, is evidenced and coexists with the rhombohedral symmetry in the low-temperature region. This field-induced phase is manifested by an extra dielectric peak observed near 373 K for the <211>cub orientation.
Optical and Electrical Properties of Sol-Gel Processed Gd Doped Ferroelectric PLZT Thin Films
Authors: Thomas Reji , Mochizuki Shoich , Mihara Toshiyuki , Ishida Tadashi
Published: June 2019

Gadolinium(Gd) doped ferroelectric lead lanthanum zirconate titanate (PLGZT 6/2/65/35) thin films were prepared by sol-gel spin coating technique. Fused silica and platinized silicon were used as substrates. Two-step pre-annealing heat treatment was employed to prepare crack free films. Annealing temperature was optimized though the x-ray diffraction studies to prepare films in single perovskite phase. Effects of Pb concentration and the seeding layer on the crystallization were studied. Optical transmission spectra were recorded and from this, refractive index, extinction coefficient and thickness were calculated for amorphous films on fused silica annealed at 400°C. In addition, the resultant films showed more than 60% transmission in the visible region. The electrical measurements were conducted on metal-ferroelectric-metal (MFM) capacitors. Ferroelectric properties of crystalline films were studied by plotting the P-E hysteresis loop.
Oxygen Vacancies in Perovskite and Related Structures: Implications for the Lower Mantle
Authors: McCammon Catherine A. , Becerro Ana Isabel , Lauterbach Stefan , Bläß Ulrich , Marion Stefan , Langenhorst Falko , Angel Ross J. , Aken Peter van , Seifert Friedrich
Published: June 2019

The oxygen vacancy ordering process and displacive transitions have been characterised in the system CaTiO3-CaFeO2.5 as a function of composition and temperature at atmospheric pressure using X-ray diffraction, Mössbauer spectroscopy, infrared spectroscopy, transmission electron microscopy, electron energy loss spectroscopy, neutron diffraction and electrical conductivity methods. With increasing concentration of vacancies the following sequence is observed: isolated defects → short defect chains → infinite chains in layers. Similar experiments at high pressures and temperatures have been conducted to determine the nature of oxygen vacancies in the lower mantle phases (Mg,Fe)(Si,Al)O3-σ and Ca(Si,Fe)O3-σ perovskite.
Characterization of Sol Gel Prepared KTN Thin Films and Powders by Raman, XRD, and Thermal Analysis Techniques.
Authors: Savvinov A.A. , Majumder S.B. , Katiyar R.S.
Published: June 2019

The renewed interest in KTa1-xNbxO (KTN) mixed perovskite materials is connected with their remarkable dielectric properties in the dilute compositions. KTN thin films with x = 0.35 have been prepared on different substrates by sol-gel technique as well as a set of powders with x = 0, 0.05, 0.1, 0.25, 0.48, 0.65, 0.75, and 1. Properties of the material change drastically with the change of x, because of relaxation of both translational and inversion symmetry due to a static disorder in the Nb distribution and the dynamic effect of a precursor ferroelectric order above Tc. Special attention was paid to the characteristic feature of coupling of the single-phonon state to a two-acoustic-phonon feature through anharmonic terms in the potential function as well as behavior of the TO3 mode which becomes a narrow peak of the first-order scattering in the tetragonal ferroelectric phase and shows a tendency to split below Tc2 in the orthorhombic phase. The wide range of x allows better understanding of dynamic processes in the KTN bulk materials which in turn helps in the studies of thin films. The above mentioned materials were studied using Raman scattering, XRD, and thermal analysis techniques.
Influence of Interfaces on the Phase Stability in Nanostructured Thin Film Multilayers
Authors: Thompson G.B. , Banerjee R. , Dregia S.A. , Fraser H.L.
Published: June 2019

Nanostructured thin film multilayers, comprising of alternating A/B layers, can exhibit metastable structures in one or both layers. From a classical thermodynamic viewpoint, the reduction interfacial energy is primarily responsible for this stabilizing effect. Based on this idea, a model has been constructed in which phase stability regions are represented as functions of both the bilayer thickness and volume fraction of the one the layers. Applying this classical thermodynamic model to a single, previously reported hcp to bcc transformation in Zr for Zr/Nb multilayers, a phase stability diagram was proposed. Various Zr/Nb multilayers with different bilayer thicknesses and volume fractions have been sputtered deposited. hcp to bcc transformations in the Zr layer were confirmed by x-ray and electron diffraction. Furthermore the Zr/Nb stability diagram predicted a novel hcp Nb phase which was subsequently verified experimentally. Using Zr/Nb as a guide, a similar phase stability diagram was constructed and experimentally determined for Ti/Nb multilayers. For each multilayer system, the reduction in interfacial energy was calculated from the experimentally determined diagram. These values were then compared to estimations of the structural component of the interfacial energy. The structural component was based on the energy per unit area of a misfit dislocation network constructed by an o-lattice. This simple assesment suggests that the reduction of the structural component of the interfacial energy is sufficient to drive the transformation.
Quantitative High-Resolution Transmission Electron Microscopy of III-V Semiconductor Interfaces by Multivariate Statistical Analysis of Exit-Plane Wave Function Images
Authors: Mahalingam Krishnamurthy , Eyink Kurt G. , Brown Gail J. , Dorsey Donald L.
Published: June 2019

The application of exit-plane wave function (EPWF) images for an atomic-scale compositional mapping of interfaces in the GaAs-AlAs system is investigated. Image simulations based on the multislice algorithm were performed to obtain EPWF images over a wide range of compositions and specimen thicknesses. The EPWF-amplitude images were further analyzed by the method of factorial analysis of correspondence. A simultaneous analysis of the effects both thickness and composition on image contrast yielded two eigenvectors representing the individual contributions from the two effects. This separation was however not complete, leaving a residual contribution from thickness on the composition-sensitive eigenvector and vice versa. Extraction of the chemical content from the composition-sensitive eigenvector is still possible by a parameterization of the residual thickness contribution. A simpler procedure for quantifying the composition across an interface is proposed based on the analysis of images of AlxGa(1-x)As with different Al/Ga composition but same specimen thickness.
Closed-Cell Mesostructured Porous Silica Films Templated by PS-b-PEO Without Additional Microporosity
Authors: Yu Kui , Smarsly Bernd , Brinker Jeffrey
Published: June 2019

Mesostructured silica/diblock films with a 3D arrangement of spherical domains (bcc) were prepared through evaporation-induced self-assembly (EISA) using polystyrene-blockpoly( ethylene oxide) diblock copolymers as structure-directing agents and TEOS (Si(OCH2CH3)4) and/or MTES (Si(OCH2CH3)3CH3) as silica precursors. A detailed small angle x-ray scattering (SAXS) analysis of the calcined mesoporous films showed that, in contrast to recently reported studies, no additional microporosity due to the PEO was observed, indicating that the PEO block formed a layer at the interface between the PS domain and the silica matrix and thus contributed to the mesopore volume. These mesostructured porous silica films are believed to be the first in respect of isolated spheres with a 3D array distributed in a silica matrix without additional microporosity and with MTES as silica precursor. Such closed-cell mesostructured porous materials with high porosity and controllable hydrophobicity can be excellent candidates for low dielectric (K) insulator materials.
Plasmon Scanned Surface-Enhanced Raman Scattering Excitation Profiles
Authors: Haynes Christy L. , Van Duyne Richard P.
Published: June 2019

Since the discovery of surface-enhanced Raman spectroscopy (SERS) in 1977, scientists have come to understand the enhancement mechanism, but have been unable to consistently optimize the weak signals inherent in Raman experiments. Surface-enhanced Raman signals originate from excitation of the localized surface plasmon resonance (LSPR) of a nanostructured metal surface, thus producing concentrated electromagnetic fields at the surface of the nanostructure. Design of the nanostructured metal substrate plays an important role in understanding and optimizing SERS experiments. In this research, the size-dependent optical properties accessible by nanosphere lithography (NSL) are exploited to fabricate topographically predictable SERS-active substrates with systematically varying LSPRs. Correlated microextinction and micro-Raman measurements, as well as quantitative implementation of a Raman standard, allow significant improvements over the current method used to optimize SERS experiments. The knowledge gained in the novel plasmon scanned SERS excitation profiles clearly indicates the substrate parameters necessary for experimental optimization and promotes further understanding of the SERS enhancement mechanism.
Electrochromic WO3-x and Colossal Magnetoresistive (La, Sr)MnO3 Perovskite Oxide Thin Films by Pulsed Laser Deposition
Authors: Mitsugi Fumiaki , Hiraiwa Eiichi , Ikegami Tomoaki , Ebihara Kenji , Suda Yoshiaki
Published: June 2019

The functional oxide thin films of electrochromic WO3-x and colossal magnetoresistive La0.8Sr0.2MnO3 were prepared by a KrF excimer pulsed laser deposition technique. Optical transparency and electrical conductivity of the WO3-x film were changed by the oxygen content in the lattice. Triclinic, tetragonal and amorphous WO3-x films were prepared by adjusting the oxygen atmosphere during the deposition. We revealed the relationship between the crystal structure and the gas sensing property of the films. The triclinic WO3-x film (1 μm) showed the high sensitivity to NO (60 ppm) gas at an operating temperature of 150°C. The colossal magnetoresistive La0.8Sr0.2MnO3 thin film having the MR ratio of 15 % (H=7 kG) was deposited under the conditions of the laser energy density of 2 J/cm2 (5Hz), substrate temperature of 850°C and oxygen pressure of 500 mTorr. The magnetic sensor composing of the La0.8Sr0.2MnO3 thin film responded to the AC magnetic field (1 kHz).
Formation of Nanometer-Scale Dot Arrays from Diblock Copolymer Templates
Authors: Black C. T. , Guarini K. W. , Sandstrom R. L. , Yeung S. , Zhang Y.
Published: June 2019

We have developed four different fabrication processes based on self-organizing diblock copolymers that all produce densely-spaced, uniformly-sized nanometer-scale dot arrays over large wafer areas. We demonstrate the versatility of these techniques through examples of dot arrays formed of metallic, insulating, and polymeric materials. These fabrication processes vary in complexity, utility, and degree of optimization, and we discuss the relative merits of each. The ability to create uniform nanoscale features below lithographic resolution limits may enable key applications in fields such as magnetic recording and microelectronics.
Laser Oscillation in Aggregates of Ultrasmall Si Nanoparticles
Authors: Nayfeh Munir H.
Published: June 2019

We dispersed electrochemically etched Si into ultrabright ultrasmall nanoparticles, with brightness higher than fluorescein or rhodamine. The emission from single particles is readily detectable. Aggregates or films of the particles exhibit emission with highly nonlinear characteristics. We observe directed blue beams at ∼ 410 nm between faces of aggregates excited by femtosecond radiation at 780 nm; and at ∼ 610 nm from aggregates of red luminescent Si nanoparticles excited by radiation at 550-570 nm from a mercury lamp. Intense directed Gaussian beams, a pumping threshold, spectral line narrowing, and speckle patterns manifest the emission. The results are analyzed in terms of population inversion and stimulated emission in quantum confinement-induced Si-Si dimer phase, found only on ultrasmall Si nanoparticles. This microlasing constitutes an important step towards the realization of a laser on a chip.
Investigations of Substrate-Selective Covalent Attachment for Genetically-Engineered Molecular Interconnects
Authors: Rana N. , Bousman K. , Shekhawat G. S. , Sirinakis G. , Heuchling F. , Welch J. , Eisenbraun E. T. , Geer R. E. , Kaloyeros A. E.
Published: June 2019

Experimental investigations are presented regarding the surface-selective molecular selfassembly of fluorinated monochloroalkylsilane of the type (heptadecafluoro-1,1,2,2-tetrahydrodecyl) dimethylchlorosilane (denoted F17) on silicon dioxide (SiO2) and silicon nitride (Si3N4) surfaces. The goal is to investigate the controlled and selective surface self-assembly of these molecules as a potential route for substrate-selective covalent bonding of complex molecular assemblies to semiconductor substrates for on-chip interconnect and device applications. X-ray photoelectron spectroscopy (XPS), x-ray reflectivity (XRR) and atomic force microscopy (AFM) have been used to investigate the selectivity of the F17 self-assembly. Contrary to previous reported results, a high degree of F17 monolayer attachment selectivity is consistently observed between SiO2 and Si3N4 substrates for all three of the aforementioned monolayer characterization methods.