Ferroelectric photovoltaic properties in doubly substituted (Bi0.9La0.1)(Fe0.97Ta0.03)O3 thin films

This work was supported by the DOE-EPSCoR Grant No. DE-FG02-08ER46526. Acknowledgment is also due to NSF Grant No. #1002410 for providing fellowships to R.K.K., D.B., and J.S.Y.Doubly substituted [Bi0.9La0.1][Fe0.97Ta0.03]O3 (BLFTO) films were fabricated on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition. The ferroelectric photovoltaic properties of ZnO:Al/BLFTO/Pt thin film capacitor structures were evaluated under white light illumination. The open circuit voltage and short circuit current density were observed to be ∼0.20 V and ∼1.35 mA/cm2, respectively. The band gap of the films was determined to be ∼2.66 eV, slightly less than that of pure BiFeO3 (2.67 eV). The PVproperties of BLFTO thin films were also studied for various pairs of planar electrodes in different directions in polycrystalline thin films.Publisher PDFPeer reviewe

Caracterización de óxido de grafeno sintetizado mediante un método de Hummers modificado

Graphene oxide (GO) has garnered significant interest due to its exceptional and tunable properties, which make it a promising candidate for a wide range of engineering applications, including composite material fabrication and water treatment. In this study, GO was synthesized from graphite flakes using a modified Hummers method involving a reduced amount of sulfuric acid. The resulting material was characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). These techniques enabled a clear differentiation between the morphology of the synthesized GO and that of the original graphite. The GO exhibited a substantially altered structure, with increased thickness likely due to the incorporation of oxygen-containing functional groups on its basal plane. FTIR analysis confirmed the presence of characteristic functional groups such as hydroxyl, carbonyl, and carboxyl. XPS analysis revealed that the elemental composition of the synthesized GO consisted of approximately 69.7% carbon and 29.9% oxygen, with a trace amount of sulfur attributed to the reagents used in the synthesis. The observed changes in morphology and composition suggest the successful synthesis of GO with potential for functionalization and application in diverse engineering contexts.El óxido de grafeno ha despertado un creciente interés debido a sus propiedades únicas y potencialmente ajustables, las cuales abarcan aplicaciones que van desde la fabricación de materiales compuestos hasta el tratamiento de aguas. Por esta razón, se desarrolló un proceso de síntesis de óxido de grafeno basado en el método de Hummers con una reducción en la cantidad de ácido sulfúrico empleada. El material obtenido fue caracterizado mediante diferentes técnicas, incluyendo microscopía electrónica de barrido (MEB), espectroscopía infrarroja transformada de Fourier (IR-TF) y espectrometría fotoelectrónica por rayos X (XPS). Estas técnicas experimentales permitieron distinguir las diferencias morfológicas entre el óxido de grafeno sintetizado y el grafito utilizado como precursor. Adicionalmente, se determinó la composición química del polvo obtenido, así como la relación entre carbono y oxígeno, con el fin de evaluar su viabilidad para aplicaciones específicas. Se observó que la morfología del óxido de grafeno difiere significativamente de la del grafito de partida. En particular, el espesor de las láminas de óxido de grafeno se incrementó debido a la incorporación de grupos funcionales oxigenados en el plano basal. El espectro FTIR del óxido de grafeno confirmó la presencia de diversos grupos funcionales, como el hidroxilo (-OH), carbonilo (C-O) y carboxilo (-COOH). Por su parte, la espectroscopía XPS reveló que la composición química del óxido de grafeno obtenido fue de 69,7 % de carbono y 29,9 % de oxígeno, con una traza mínima de azufre atribuida a los reactivos empleados durante el proceso de síntesis

Ferroelectric Capped Magnetization in Multiferroic PZT/LSMO Tunnel Junctions

Self-poled ultra-thin ferroelectric PbZr0.52Ti0.48O3 (PZT) (5 and 7 nm) films have been grown by pulsed laser deposition technique on ferromagnetic La0.67Sr0.33MnO3 (LSMO) (30 nm) to check the effect of polar capping on magnetization for ferroelectric tunnel junction (FTJ) devices. PZT/LSMO heterostructures with thick polar PZT (7 nm) capping show nearly 100% enhancement in magnetization compared with thin polar PZT (5 nm) films, probably due to excess hole transfer from the ferroelectric to the ferromagnetic layers. Core-level X-ray photoelectron spectroscopy studies revealed the presence of larger Mn 3s exchange splitting and higher Mn3+/Mn4+ ion ratio in the LMSO with 7 nm polar capping.Comment: 17 pages, 5 figure

Glycan-dependent binding of galectin-1 to neuropilin-1 promotes axonal regeneration after spinal cord injury

Following spinal cord injury (SCI), semaphorin 3A (Sema3A) prevents axonal regeneration through binding to the neuropilin-1 (NRP-1)/PlexinA4 receptor complex. Here, we show that galectin-1 (Gal-1), an endogenous glycan-binding protein, selectively bound to the NRP-1/PlexinA4 receptor complex in injured neurons through a glycan-dependent mechanism, interrupts the Sema3A pathway and contributes to axonal regeneration and locomotor recovery after SCI. Although both Gal-1 and its monomeric variant contribute to de-activation of microglia, only high concentrations of wild-type Gal-1 (which co-exists in a monomer-dimer equilibrium) bind to the NRP-1/PlexinA4 receptor complex and promote axonal regeneration. Our results show that Gal-1, mainly in its dimeric form, promotes functional recovery of spinal lesions by interfering with inhibitory signals triggered by Sema3A binding to NRP-1/PlexinA4 complex, supporting the use of this lectin for the treatment of SCI patients.Fil: Quintá, Héctor Ramiro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Fisicoquímica Biológicas; ArgentinaFil: Pasquini, Juana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Fisicoquímica Biológicas; ArgentinaFil: Rabinovich, Gabriel Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Pasquini, Laura Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Fisicoquímica Biológicas; Argentin

Propiedades multiferroicas de la estructura multicapas BiFeO3 /CoFe2 O4 a temperatura ambiente

Las películas multicapa BiFeO3 /CoFe2 O4 se depositaron mediante recubrimiento por rotación sobre 3 2 4 sustratos de Pt (Pt / TiO2 / SiO2 / Si) y se recocieron a 700, 725 y 750 ° C. El precursor de BiFeO3/CoFe2O4 para la estructura de multicapas se sintetizó por el método de solución química. Los patrones de difracción de rayos X del sistema de multicapas revelaron la estructura de tipo compuesto. La corriente de fuga se encontró a menos de 10 Amp en el campo eléctrico por debajo de 100 kV / cm, que muestra el -6 comportamiento óhmico de BiFeO /CoFe O . La constante dieléctrica disminuye al aumentar en el rango de 3 2 4 frecuencia 103-106 Hz. El sistema BiFeO /CoFe O muestra la coexistencia de polarización ferroeléctrica 3 2 4 (Pr) = 65 y 51 μC / cm2 y magnetización (Mr) = 102 y 47 emu / cm3 a temperatura ambiente. Las respuestas ferromagnéticas y ferroeléctricas observadas en el sistema de multicapas pueden ser útiles para dispositivos bifuncionales

Persistence of airborne tree pollen from the Cupressaceae family during the last decade in the city of Bahia Blanca

Airborne pollen is a major contributor to allergic respiratory diseases. However, the literature on patterns and seasonality of specific pollen types mainly comes from northern hemisphere and developed regions, limiting our ability to extrapolate these findings to other geographical locations. With this research letter, our aim is to contribute to the current knowledge of aerobiology by analyzing the decade-long patterns of airborne tree pollen in the city of Bahia Blanca, Argentina. In general, we found late winter to early spring as the period with the highest Cupressaceae pollen counts. In 2020, the average pollen count during July through September was 78.81 (SD 79.70), the highest recorded during the last 10 years. These months had varying pollen concentrations from moderate (15-89 grains/m3 of air) to high (90-1499 grains/m3 of air). Regardless of such variation, August had consistently been the month with the highest peak concentrations from 2010 to 2020 (61.2, SD 57.3), followed by September (27.1, SD 20.3). We did not find any month with very high (>1500 grains/m3 of air) peak concentration. Further studies need to be done to expand our knowledge on aerobiology to characterize specific pollen sub-types and determine the exact allergenic potential of airborne pollen in different regions.Fil: Ramon, German D.. Hospital Italiano Regional del Sur; ArgentinaFil: Felix, Miguel. Universidad Espíritu Santo; EcuadorFil: Barrionuevo, Laura B.. Hospital Italiano Regional del Sur; ArgentinaFil: Benedetti, Graciela María. Universidad Nacional del Sur. Departamento de Geografía y Turismo; ArgentinaFil: Duval, Valeria Soledad. Universidad Nacional del Sur. Departamento de Geografía y Turismo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Vanegas, Emanuel. Universidad Espíritu Santo; EcuadorFil: Cherrez Ojeda, Ivan. Universidad Espíritu Santo; Ecuado

Complete male-to-female sex reversal in XY mice lacking the miR-17~92 cluster

Mammalian sex determination is controlled by antagonistic gene cascades operating in embryonic undifferentiated gonads. The expression of the Y-linked gene SRY is sufficient to trigger the testicular pathway, whereas its absence in XX embryos leads to ovarian differentiation. Yet, the potential involvement of non-coding regulation in this process remains unclear. Here we show that the deletion of a single microRNA cluster, miR-17~92, induces complete primary male-to-female sex reversal in XY mice. Sry expression is delayed in XY knockout gonads, which develop as ovaries. Sertoli cell differentiation is reduced, delayed and unable to sustain testicular development. Pre-supporting cells in mutant gonads undergo a transient state of sex ambiguity which is subsequently resolved towards the ovarian fate. The miR-17~92 predicted target genes are upregulated, affecting the fine regulation of gene networks controlling gonad development. Thus, microRNAs emerge as key components for mammalian sex determination, controlling Sry expression timing and Sertoli cell differentiation

Influencia de la irradiación en la calidad nutritiva del trigo y la merluza

Se estudia el efecto de la irradiación y tiempo de conservación sobre el valor nutritivo del trigo. La dosis de irradiación fue de 37,5 Krad. El tiempo transcurrido desde la fecha de recolección hasta ser sometido a irradiación fue de 150 días, y desde esta fecha hasta ser consumido por los animales pasaron 90 días. La determinación analítica química, se ha realizado a los 605 días de la recolección. Las técnicas seguidas para la valoración de la proteína han sido: una biológica, la de Thomas Mitchell, y otra analítica química, el aminograma, según la técnica de Moore-Stein. Para la determinación de hidratos de carbono disponibles se ha utilizado la técnica de Friedemann y col. De acuerdo con los resultados obtenidos, llegamos a la conclusión de que desde el punto de vista nutritivo, la irradiación es un método adecuado de conservación de trigo, ya que no influye la calidad del mismo, juzgada por la disponibilidad de los hidratos de carbono y por la digestibilidad de la proteína. Por otra parte la irradiación disminuye pérdidas en aminoácidos durante el almacenamiento. Hemos estudiado también la influencia de la irradiación sobre el valor nutritivo de filetes de merluza (Merlucius merlucius). La dosis de irradiación fue de 100 Krad.; la experiencia biológica se realizó según la técnica ya citada de Thomas-Mitchell. Concluímos que la irradiación no influye significativamente sobre la digestibilidad ni la calidad nutritiva de la proteína de merluza.We have studied the effect of the irradiation and the time of conservation on nutritional value. The irradiation dose was of 37,5 Krad.; the time past from the date of harvest untill the irradiation was 150 days and from this date untill that was given to the animals past 90 days. The ana tic al determination was realized to 605 days after harvest. The Thomas Mitchell technique has been used in estimating its protein quality and that of Moore-Stein in determining the aminogram. The Friedeman and col., technique for the carbohidrates usable. According to results obtained we came to the conclusion that, from a nutritional point of view, irradiation is a suitable method for the preservation of wheat, because don't affect the quality of its self judged for the carbohydrates availability and for the protein digestibility. Furthermore, irradiation diminishes the loss of aminoacids during storage. Moreover, we have studied the influence of the irradiation on nutritional value of hake fillet (Merlucius merlucius). The irradiation dose was lOO. Krad.; the irradiation has no significant effects on the digestibility, neither the nutritive quality of have protein

Efficient generation of highly crystalline carbon quantum dots via electrooxidation of ethanol for rapid photodegradation of organic dyes

Achieving versatile routes to generate crystalline carbon-based nanostructures has become a fervent pursuit in photocatalysis-related fields. We demonstrate that the direct electrooxidation of ethanol, performed on Ni foam, yields ultra-small and highly crystalline graphene-like structures named carbon quantum dots (CQDs). We perform simulations of various sp2 and sp3 domains in order to understand the optical properties of CQDs by accounting their contribution as absorbance/luminescent centers in the overall optical response. Experiments and simulations reveal that absorbance bands for as-synthesized CQDs are dominated by small sp2 domains comprised of r7 aromatic-rings. After 48 h synthesis, the dispersion transition from yellow to red, exhibiting new and red shifted absorbance bands. Furthermore, fluorescence emission is governed by medium-sized sp 2 domains (with aromatic ring counts r12) and oxygen-containing groups. These oxygen-rich groups within the CQDs, confirmed by FT-IR and XPS, are responsible for the fast photodegradation of organic dyes, with B90% of methylene blue (MB) being degraded within the first 5 min of light exposure. Our work provides crucial insights about the electrochemical synthesis and overall optical properties of carbon nanostructures, while being effective and reliable toward the degradation of contaminants in water