568 research outputs found
Surface modification: surface coating rescues proteins from magnetite nanoparticle induced damage (part. Part. Syst. Charact. 8/2013)
No full textThe image shows the major findings of Goutam De, Krishnananda Chattopadhyay, and coworkers, who studied the interaction between iron oxide nanoparticles and cytochrome c, as reported on page 683. The triangle at the top left shows the binding of the protein onto the surface of the bare particles forming amyloid fibrils (transmission electron microscopy image is shown in the background). Appropriate surface modification inhibits protein binding and amyloid formation (shown in the triangle at the bottom right)
Preparation of uniformly dispersed copper nanocluster doped silica glasses by the sol gel process
No full textThe synthetic mechanism of uniformly dispersed Cu-nanocluster doped (0.05-1.0 wt%) silica glasses (copper ruby glasses) was investigated by UV-VIS and FTIR spectroscopy, DSC, XRD, surface area and density measurements at different stages of drying/densification up to glass formation. The monolithic gels were prepared from Cu(NO3)2, H2N(CH2)2NH(CH2)3Si (OCH3)3 (DAMO) and acid hydrolysed Si(OH2H5)4 (TEOS). DAMO was used to immobilize the Cu2+ ions in the silica matrix. The formation and decomposition of Cu-DAMO complexes in the silica gel monoliths were studied. The doped gels were densified under H2 and He gas atmospheres. A maximum matrix (SiO2) density of 1.70-1.73 g cm-3 (77-79% of the theoretical density) could be achieved in an H2 atmosphere at 900°C. However a density close to silica glass 2.17 g cm-3 (>98.5% of theoretical) was achieved when the gels were densified in H2 up to 800°C followed by He gas at 980°C. The surface area data also confirmed this densification behaviour. Uniformly dispersed Cu metal nanoclusters were formed during the heat-treatment of the gels and as a result a surface plasmon (SP) band of Cu-nanoclusters (563-580 nm) was observed. The increase of heat-treatment temperature caused the growth of nanoclusters and as a consequence the SP band was blue-shifted. XRD data also confirmed this
FIG. 5 in A New Genus and Two New Species of Arboreal Toads from the Highlands of Sumatra with a Phylogeny of Sundaland Toad Genera
No full textFIG. 5.—Habitat of Sigalegalephrŋnus mandailinguensis—a view of the rainforest at the edge of an inactive solphatara field on the northeastern slope of Gunung Sorikmarapi where the holotype was found (upper); and first author at the entrance of the subterranean hollow where the holotype was collected (lower).Published as part of Smart, Utpal, Sarker, Goutam C., Arifin, Umilaela, Harvey, Michael B., Sidik, Irvan, Hamidy, Amir, Kurniawan, Nia & Smith, Eric N., 2017, Herpetologica 73 (1) on pages 63-75, DOI: 10.1655/Herpetologica-D-16-00041, http://zenodo.org/record/771643
ENTIRE FUNCTIONS SHARING POLYNOMIALS WITH THEIR DERIVATIVES
No full textIn this paper we study the uniqueness of entire functions sharing two polynomials with their derivatives. The results of the paper improve the corresponding results of Chang and Fang (Kodai Math.J. 25(2002), 309–320) and Lahiri-Ghosh(Present author) (Analysis ,Munich. 31(2011), 47–59)
Degomagem de óleo de soja por ultrafiltração
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Alimentos.O refino tradicional do óleo de soja bruto consiste em submeter o produto às etapas de degomagem (retirada dos fosfolipídios), neutralização, branqueamento e desodorização. Recentemente, os processos de separação por membranas, notadamente a ultrafiltração, vêm despertando a atenção dos pesquisadores como uma alternativa viável, na etapa de degomagem do óleo, em substituição ao processo tradicional que utiliza adição de água quente ou vapor. A ultrafiltração apresenta algumas vantagens em relação ao processo tradicional, como redução no consumo de energia, eliminação do tratamento de águas residuárias e obtenção dos fosfolipídios, sem adição de produtos químicos. Neste trabalho, membranas de PES (Polietersulfona), puras ou combinadas com aditivos orgânicos e inorgânicos, foram preparadas através da técnica de inversão de fase. As membranas foram testadas quanto a permeabilidade à água, ao óleo puro e à micela hexano/óleo bruto em diferentes concentrações. Nos ensaios de filtração, utilizou-se uma célula de ultrafiltração, pressurizada com nitrogênio e operada com fluxo perpendicular. As membranas foram testadas sob diferentes condições operacionais. A membrana, denominada de MR4, composta de 20% de PES, apresentou os melhores resultados quando se considerou o fluxo permeado e a retenção de fosfolipídios. Conseguiu-se uma retenção de fosfolipídios da ordem 98,4%, utilizando-se a micela hexano/óleo bruto (3:1). Através de análise morfológica e funcional verificou-se a resistência físico-química da membrana frente ao hexano. A maior resistência que limita o fluxo de permeado foi devida à própria membrana durante a filtração. Foi testada ainda a dessolventização da micela através de membranas de osmose inversa
Etude de délétions chromosomiques et de variants génétiques responsables de mortalité embryonnaire chez les bovins laitiers
No full textThe overall aim of this PhD thesis is to identify causal variants for recessive lethal mutations and select a set of predictive markers that are in high linkage-disequilibrium with the causal variants for female fertility in dairy cattle. We addressed this broad aim under five articles: (i) describes a systematic approach of mapping recessive lethals in French Normande cattle using homozygous haplotype deficiency (HHD). This study shows the influence of sample size, quality of genotypes, quality of (genotype) phasing and imputation, age of haplotype (of interest), and last but not the least, multiple testing corrections, on discovery and replicability of HHD results. It also illustrates the importance of fine-mapping with pedigree and whole-genome sequence (WGS) data, (cross-species) integrative annotation to prioritize candidate mutation, and finally, large-scale genotyping of the candidate mutation, to validate or invalidate initial results. (ii) describes a high-resolution population-scale mapping of large chromosomal deletions from whole-genome sequences of 175 animals from three Nordic dairy breeds. This study employs three different approaches to validate identified deletions. Next, it describes population genetic properties and functional importance of these deletions. (iii) deals with three main issues related to imputation of structural variants, in this case, large chromosomal deletions, e.g. availability of deletion genotypes, size of haplotype reference panel, and finally, imputation itself. To address the first two issues, this study describes a Gaussian mixture model-based approach where read-depth data from the variant call format (VCF) file is used to genotype a known deletion locus, without the need for raw sequence (BAM) file. Finally, it presents a pipeline for joint imputation of WGS variants along with large chromosomal deletions. (iv) describes genome-wide association studies for female fertility in three Nordic dairy cattle breeds using imputed WGS variants including large chromosomal deletions. This study is based on the analyses of eight fertility related traits using single-marker association, conditional and joint analyses. This study illustrates that inflation in association test-statistics could be seen even after correcting for population stratification using (genomic) principal components, and relatedness among the samples using genomic relationship matrices; however, this was known for traits with strong polygenic effects, among other factors. Finally, mapping of several new quantitative trait loci (QTL), along with the previously known ones, are reported in this study. This study also highlights the importance of including (imputed) large deletions for association mapping of fertility traits. (v) describes prediction of genomic breeding values for fertility using SNP array-chip genotypes, selected QTL and large chromosomal deletion. Using genomic best linear unbiased prediction (GBLUP) method with one or several genomic-relationship matrices derived from a set of selected markers, this study reports higher prediction accuracy compared with previous report. This study also highlights the influence of selecting markers with best predictability, especially for a breed with small training population, in accuracy of genomic prediction. The results demonstrate that large deletions in general have a high predictive performance.L'objectif général de cette thèse est d'identifier les variants causaux ou, à défaut, un ensemble de marqueurs prédictifs - qui présentent un déséquilibre de liaison élevé avec les variants causaux - pour la fertilité des vaches laitières. Nous avons abordé cet objectif général dans cinq articles: (i) décrit une approche systématique de cartographie des variants létaux récessifs chez les bovins Normands français basée sur la recherche de déficit en haplotypes homozygotes (HHD). Cette étude montre l’influence de la taille de l’échantillon, de la qualité des génotypes, de la qualité du phasage des génotypes en haplotypes et de l’imputation, de l’âge de l’haplotype et enfin, de la définition des seuils de signification prenant en compte les tests multiples, sur la découverte et la reproductibilité des résultats de HHD. Elle illustre également l’importance de la cartographie fine avec les données de généalogie et de séquence de génome entier (WGS), l’annotation intégrative (entre espèces) pour hiérarchiser les mutations candidates et, enfin, le génotypage à grande échelle de la mutation candidate, pour valider ou invalider les mutations initiales. (ii) décrit une cartographie à haute résolution de grandes délétions chromosomiques de séquences du génome dans une population de 175 animaux appartenant à trois races laitières nordiques. Cette étude utilise trois approches différentes pour valider les résultats de la cartographie. Le chapitre décrit les propriétés génétiques des populations et l’importance fonctionnelle des délétions identifiées. (iii) traite de trois questions liées à l’imputation de variants structuraux, ici de délétions chromosomiques importantes: la disponibilité des génotypes de délétion, la taille du panel de référence d'haplotypes et, enfin, l’imputation elle-même. Pour aborder les deux premières questions, cette étude décrit une approche basée sur un modèle de mélange gaussien dans laquelle les données de profondeur de lecture provenant de fichiers au format VCF (variant call format) sont utilisées pour génotyper un locus de délétion connu, en l’absence d’information sur la séquence brute. Enfin, il présente un pipeline pour l'imputation conjointe de variants WGS et de grandes délétions chromosomiques. (iv) décrit des études d'association pangénomiques de la fertilité femelle dans trois races de bovins laitiers nordiques à l'aide de variants WGS imputés et de grandes délétions chromosomiques. Cette étude concerne huit caractères de fertilité et utilise des analyses d'association mono-marqueur, conditionnelles et conjointes. Cette étude montre qu’une surestimation, ou « inflation », des statistiques de test peut être observée même après correction pour la stratification de la population à l'aide de composantes principales génomiques et pour les structures familiales à l'aide de matrices de relations génomiques. Ce biais était connu pour les caractères très polygéniques. Enfin, cette étude présente plusieurs locus de traits quantitatifs (QTL) nouveaux et confirme plusieurs autres déjà connus. Elle souligne également l’importance d’inclure les grandes délétions (imputées) pour la cartographie par association des caractères de fertilité. (v) décrit la prédiction des valeurs génomiques de fertilité (ou indice de fertilité) à l'aide de génotypes à puces SNP, de QTL sélectionnés et de délétions chromosomiques importantes. En utilisant la méthode de meilleure prédiction linéaire sans biais génomique (GBLUP) avec une ou plusieurs matrices de relations génomiques dérivées d'un ensemble de marqueurs sélectionnés, cette étude rapporte une précision de prédiction améliorée. Cette étude met également en évidence l’influence de la sélection des marqueurs les plus prédictifs, en particulier pour une race ayant une population d’apprentissage réduite, sur la précision des prédictions génomiques. Enfin, les résultats démontrent que les grandes délétions ont en général un pouvoir prédictif élevé
Comparative 4-E analysis of a bottoming pure NH3 and NH3-H2O mixture based power cycle for condenser waste heat recovery
No full textHigh-power, continuous-wave optical parametric oscillators from visible to near-infrared
No full textThis thesis presents the development of a new class of high-power, continuous-wave (cw) optical parametric oscillators (OPOs) with extended tunability from visible to near-infrared (near-IR). While lasers have been in use for nearly 50 years, it is still difficult to develop laser systems that can cover many regions of the optical spectrum, from ultraviolet (UV) and visible to the near and mid-infrared wavelength range, with potential applications in the fields such as spectroscopy, remote sensing, trace gas detection, and many more.
Development of cw OPOs in singly-resonant oscillator (SRO) configurations, the focus of this thesis, is challenging due to the high threshold pump power (several watts). In addition, with visible pumping, photorefractive effect and thermal lensing effects become important issues to overcome. Therefore, the realization of practical cw SROs requires optimal cavity design, suitable nonlinear materials, and high-power laser with high spectral and spatial quality.
High-power, single-frequency, cw SROs based on 30-mm-long MgO-doped, stoichiometrically grown, periodically-poled LiTaO3 (MgO:sPPLT) have been developed. The oscillators were pumped in the green by a frequency-doubled cw diode-pumped Nd:YVO4 laser at 532 nm. With a single grating period of 7.97 µm, continuous signal and idler coverage over 848-1430 nm is obtained by temperature tuning between 52 oC and 248 oC. In a linear cavity configuration and double-pass pumping, an oscillation threshold of 2.88 W has been obtained, and single-pass idler powers in excess of 1.51 W have been generated over 1104-1430 nm for 6 W of pump power at an extraction efficiency of 25.2% and photon conversion efficiency of 56.7%.
For single-frequency performance of the cw SRO across 848-1430 nm, we have used a compact ring cavity configuration along with a frequency selecting element (etalon). Using the same MgO:sPPLT crystal, the SRO oscillation threshold of 2.84 W has been obtained, and single-pass idler powers in excess of 1.59 W have been generated over 1104-1430 nm with a maximum SRO extraction efficiency of 25.2% and pump depletions as much as 67%. The single-frequency idler output has a linewidth of ~7 MHz. Under free-running conditions and in the absence of thermal isolation, the idler power exhibits a peak-to-peak stability of 16% over 5 hours.
Although the cw SRO can provide optical radiation across 848-1430 nm, the high output power was only available over 1104-1430 nm, due to the high reflectivity of the cavity mirrors for SRO operation. Using finite output coupling of the resonant wave, we have extended the available practical output power across the entire tuning range. The cw out-coupled SRO (OC-SRO) can deliver total power of up to 3.6 W at 40% extraction efficiency with a linewidth of 3 MHz across 848-1430 nm. The signal power shows a peak-to-peak power stability <10.7% over 40 minutes in a TEM00 spatial mode with M2 <1.52. Without any active stabilization, the resonant signal exhibits a natural long-term frequency stability <75 MHz over 15 minutes and short-term frequency stability <10 MHz over 10 seconds, demonstrating the potential of the system for spectroscopic applications.
Using internal second-harmonic-generation of the resonant near-infrared signal radiation of the MgO:sPPLT cw SRO in a 5-mm-long BiB3O6 crystal, we have generated 1.27 W of cw, single-frequency blue power over a tunable range of 425-489 nm with a linewidth of 8.5 MHz and a Gaussian spatial beam profile. The blue source is frequency-stable to better than 280 MHz, limited by the resolution of the wavemeter.
We have also developed cw green sources, in a simple single-pass experimental configuration by frequency-doubling a fiber laser using MgO:sPPLT and periodically-poled KTiOPO4 (PPKTP) crystals, generating as much as 9.6 W of green radiation in TEM00 spatial beam profile (M2 <1.33) with a single-pass efficiency of 32.7% in MgO:sPPLT. This green source has also successfully been used to pump cw SROs and will be used to pump Ti:sapphire lasers.
Using this frequency-doubled green source, we have demonstrated cw OC-SRO providing a stable single-frequency output power up to 2 W across the tuning range of 855-1408 nm, with peak-to-peak power stability <11.7%, frequency-stability <10 MHz over 10 seconds, in TEM00 (M2 <1.26) spatial beam profile.Esta tesis presenta el desarrollo de una nueva clase de osciladores ópticos paramétricos (OPOs) de onda continua (cw) y alta potencia con extendida sintonización desde el visible al infrarrojo (IR) cercano. A pesar de que los láseres están en uso desde hace casi 50 años, todavía es difícil desarrollar sistemas láser que puedan cubrir muchas regiones del espectro óptico en los rangos de longitud de onda desde el ultravioleta (UV) y visible hasta el infrarrojo cercano y medio, con potenciales aplicaciones en campos como la espectroscopia, sensores remotos, detección de trazas de gases, entre muchas otras.
El desarrollo de cw OPOs en configuraciones de oscilador simplemente resonante (SRO), objetivo principal de esta tesis, es un gran desafío debido al alto umbral de potencia de bombeo (varios watts). Además, cuando se emplea bombeo visible, los efectos fotorrefractivo y de lente térmica adquieren especial relevancia y son difíciles de superar. Por lo tanto, la realización de cw SROs prácticos requiere de un óptimo diseño de cavidad, adecuados materiales no lineales y láseres de alta potencia con excelente calidad tanto espectral como espacial.
Se han desarrollado cw SROs de alta potencia y frecuencia única basados en cristales de LiTaO3 de 30 mm de longitud, de crecido estequiométrico, con dopado de MgO y periódicamente pulidos (MgO:sPPLT). Los osciladores fueron bombeados en el verde mediante el láser de cw Nd:YVO4 bombeado por diodos y doblado en frecuencia. Utilizando un único periodo de red de 7.97 m, se ha obtenido cobertura continua de los campos señal y pivote en el rango 848-1430 nm por sintonización de temperatura entre 52ºC y 248ºC. Empleando una configuración de cavidad lineal y bombeo de doble paso, se ha logrado un umbral de oscilación de 2.88 W y se han generado potencias superiores a 1.51 W para el campo pivote en simple paso dentro del rango 1104-1430 nm para 6 W de potencia de bombeo, eficiencia de extracción del 25.2% y eficiencia de conversión de fotón del 56.7%.
Con el objetivo de operar el cw SRO en frecuencia única a través del rango 848-1430 nm, hemos utilizado una configuración compacta de cavidad en anillo junto a un elemento para la selección de frecuencia (etalon). Utilizando el mismo cristal de MgO:sPPLT, se ha obtenido un umbral de oscilación del SRO de 2.84 W y se han generado potencias superiores a 1.59 W para el campo pivote en paso único dentro del rango 1104-1430 nm con una eficiencia máxima de extracción del 25.2 % y agotamiento del bombeo tan alto como el 67%. La salida del campo pivote en frecuencia única tiene un ancho de línea de ~ 7 MHz. Bajo condiciones de sistema libre y en ausencia de aislamiento térmico, la potencia del campo pivote exhibe estabilidad de pico a pico de 16% durante 5 horas.
A pesar de que el cw SRO puede proveer radiación óptica en el rango 848-1430 nm, la alta potencia de salida solo se consiguió obtener en el rango 1104-1430 nm a causa de la alta reflectividad de los espejos de la cavidad para operar en SRO. Utilizando un acoplamiento de salida finito de la onda resonante, hemos extendido la disponibilidad de prácticas potencias de salida a través de todo el rango de sintonía. El cw SRO con acoplador de salida (OC-SRO) puede entregar un apotencia total de hasta 3.6 W con una eficiencia de extracción del 40% y con un ancho de línea de 3 MHz en el rango 848-1430 nm. La potencia del campo señal muestra fluctuaciones en potencia de pico a pico <10.7% durante 40 minutos y modo espacial TEM00 con M2<1.52. En ausencia de estabilización activa, el campo señal resonante exhibe una estabilidad en frecuencia natural a largo término con fluctuaciones <75 MHz durante 15 minutos, así como a corto término con fluctuaciones<10MHz durante 10 segundos, demostrando el potencial del sistema para aplicaciones en espectroscopia.
Utilizando generación interna de segundo harmónico del campo señal resonante en el rango del infrarrojo cercano del MgO:sPPLT cw SRO mediante un cristal de BiB3O6 de 5 mm de longitud, hemos logrado generar 1.27 W de potencia cw y frecuencia única en el azul dentro del rango de sintonía 425-489 nm y con un ancho de línea de 8.5 MHz y un perfil espacial del haz de tipo Gaussiano. La estabilidad en frecuencia de la fuente azul es mejor que 280 MHz, donde la limitación viene impuesta por la resolución del medidor de longitud de onda empleado.
Adicionalmente, hemos desarrollado fuentes verdes en cw en una sencilla configuración experimental de único paso, mediante el doblado en frecuencia de un láser de fibra con cristales de MgO:sPPLT y KTiOPO4 pulido periódicamente (PPKTP), generando hasta 9.6 W de radiación verde en modo espacial TEM00 (M2<1.33) con una eficiencia de paso único de 32.7% en MgO:sPPLT. Esta fuente verde has sido también empleada exitosamente para bombear cw SROs y será utilizada para bombear láseres de Ti:sapphire.
Mediante esta fuente verde doblada en frecuencia, hemos demostrado que el cw OC-SRO proporciona una salida estable en frecuencia única con potencia de hasta 2 W a través del rango de sintonía 855-1408 nm, con estabilidad en potencia de pico a pico <11.7%, estabilidad en frecuencia <10 MHZ durante 10 segundos y modo espacial TEM00 (M2<1.26).DOCTORAT EN FOTÒNICA (Pla 2007
Ultrasound-promoted metal-catalyzed synthesis of heterocyclic compounds of medicinal interest
No full textIn the last decade, sonochemistry has become an interesting field of research in both organic chemistry and pharmaceutical industry. It is well known that sonochemical effects are derived from a phenomenon known as acoustic cavitation, that is, the formation, growth, and implosion of microbubbles inside a liquid. These effects induce high temperatures (near 5000K) and very high pressures (around 1000 atmospheres) inside such cavities, while shock waves at the interface and bulk liquid are largely responsible for enhanced mass and energy transfers. By virtue of the effects mentioned above organic synthesis of heterocycles, assisted by ultrasound irradiation, constitutes a convenient way to accelerate and improve the synthesis of a great number of compounds with analgesic, antipyretic, antiinflammatory, antibacterial, and fungicidal properties. Moreover, it is important to mention that other heterocyclic compounds have been used in cancer treatment, cardiovascular disease, type 2 diabetes, migraine, and anxiety; also can be used as anticonvulsants, sedatives, and hypnotic agents. The present chapter is focused on ultrasound-promoted metal-catalyzed synthesis of heterocyclic molecules reported between 2000 and 2019.Fil: Schiel, María Ayelén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Silbestri, Gustavo Fabián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Alvarez, Monica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Domini, Claudia Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin
Sensitized photooxidation of Ortho-Prenyl Phenol: Biomimetic Dihydrobenzofuran Synthesis and Total 1O2 Quenching†
No full textThe sensitized photooxidation of ortho-prenyl phenol is described with evidence that solvent aproticity favors the formation of a dihydrobenzofuran [2-(prop-1-en-2-yl)-2,3-dihydrobenzofuran], a moiety commonly found in natural products. Benzene solvent increased the total quenching rate constant (kT) of singlet oxygen with prenyl phenol by ~10-fold compared to methanol. A mechanism is proposed with preferential addition of singlet oxygen to prenyl site due to hydrogen bonding with the phenol OH group, which causes a divergence away from the singlet oxygen ‘ene’ reaction toward the dihydrobenzofuran as the major product. The reaction is a mixed photooxidized system since an epoxide arises by a type I sensitized photooxidation.Fil: Jabeen, Shakeela. City University of New York; Estados UnidosFil: Ghosh, Goutam. City University of New York; Estados UnidosFil: Lapoot, Lloyd. City University of New York; Estados UnidosFil: Durantini, Andres Matías. City University of New York; Estados Unidos. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; ArgentinaFil: Greer, Alexander. City University of New York; Estados Unido
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