The Synthesis of Sponge-like V2O5/CNT Hybrid Nanostructures Using Vertically Aligned CNTs as Templates.

The fabrication of sponge-like vanadium pentoxide (V2O5) nanostructures using vertically aligned carbon nanotubes (VACNTs) as a template is presented. The VACNTs were grown on silicon substrates by chemical vapor deposition using the Fe/Al bilayer catalyst approach. The V2O5 nanostructures were obtained from the thermal oxidation of metallic vanadium deposited on the VACNTs. Different oxidation temperatures and vanadium thicknesses were used to study the influence of these parameters on the stability of the carbon template and the formation of the V2O5 nanostructures. The morphology of the samples was analyzed by scanning electron microscopy, and the structural characterization was performed by Raman, energy-dispersive X-ray, and X-ray photoelectron spectroscopies. Due to the catalytic properties of V2O5 in the decomposition of carbonaceous materials, it was possible to obtain supported sponge-like structures based on V2O5/CNT composites, in which the CNTs exhibit an increase in their graphitization. The VACNTs can be removed or preserved by modulating the thermal oxidation process and the vanadium thickness.

Structured light using carbon nanostructures driven by Kerr nonlinearities and a magnetic field.

A substantial influence of a magnetic field on the third-order nonlinear optical properties exhibited by aggregated networks of aligned carbon nanotubes (CNT) is reported by systematic measurements. A two-wave mixing was employed to explore and modulate the refractive index in the nanostructures in the nanosecond and picosecond regime. The presence of a magnetic field was able to modify the optical transmittance in the sample and the potentiality to generate structured light was proposed. Numerical simulations were conducted to analyze the magnetic field phenomena and the oscillations of the electric field in the studied sample. We discussed theoretical concepts, experimental methods, and computational tools employed to evaluate the third-order nonlinear optical properties of CNT in film form. Immediate applications of the system to modulate structured light can be contemplated.

Tunable Low Crystallinity Carbon Nanotubes/Silicon Schottky Junction Arrays and Their Potential Application for Gas Sensing.

Highly ordered nanostructure arrays have attracted wide attention due to their wide range of applicability, particularly in fabricating devices containing scalable and controllable junctions. In this work, highly ordered carbon nanotube (CNT) arrays grown directly on Si substrates were fabricated, and their electronic transport properties as a function of wall thickness were explored. The CNTs were synthesized by chemical vapor deposition inside porous alumina membranes, previously fabricated on n-type Si substrates. The morphology of the CNTs, controlled by the synthesis parameters, was characterized by electron microscopies and Raman spectroscopy, revealing that CNTs exhibit low crystallinity (LC). A study of conductance as a function of temperature indicated that the dominant electric transport mechanism is the 3D variable range hopping. The electrical transport explored by I-V curves was approached by an equivalent circuit based on a Schottky diode and resistances related to the morphology of the nanotubes. These junction arrays can be applied in several fields, particularly in this work we explored their performance in gas sensing mode and found a fast and reliable resistive response at room temperature in devices containing LC-CNTs with wall thickness between 0.4 nm and 1.1 nm.

Nickel Nanopillar Arrays Electrodeposited on Silicon Substrates Using Porous Alumina Templates.

Nickel nanopillar arrays were electrodeposited onto silicon substrates using porous alumina membranes as a template. The characterization of the samples was done by scanning electron microscopy, X-ray diffraction, and alternating force gradient magnetometry. Ni nanostructures were directly grown on Si by galvanostatic and potentiostatic electrodeposition techniques in three remarkable charge transfer configurations. Differences in the growth mechanisms of the nanopillars were observed, depending on the deposition method. A high correlation between the height of the nanopillars and the charge synthesis was observed irrespective of the electrochemical technique. The magnetization measurements demonstrated a main dependence with the height of the nanopillars. The synthesis of Ni nanosystems with a controllable aspect ratio provides an effective way to produce well-ordered networks for wide scientific applications.

Recomendaciones de uso de cladribina comprimidos en la esclerosis múltiple recurrente / Recommendations for the use of cladribine tablets in recurring multiple sclerosis

Introducción. La cladribina es un profármaco, análogo sintético de la desoxiadenosina, aprobado como terapia de reconstitución inmune selectiva en la esclerosis múltiple (EM) recurrente muy activa del adulto. Objetivos. Revisar el desarrollo del fármaco, su mecanismo de acción y los datos de eficacia y seguridad obtenidos hasta la fecha, y establecer recomendaciones de manejo por expertos españoles en la práctica clínica. Desarrollo. El tratamiento de la EM se ha simplificado con cladribina comprimidos, y se necesitan dos cursos cortos de administración durante dos años consecutivos (máximo 20 días) para mantener una eficacia de hasta cuatro años tras la primera dosis. Los resultados de los ensayos clínicos han demostrado la seguridad, la tolerabilidad y la eficacia a largo plazo de la cladribina comprimidos en pacientes con EM recurrente. Así, los pacientes tratados con cladribina presentaron una reducción significativa de la tasa de brotes, del riesgo de progresión de la discapacidad y del desarrollo de nuevas lesiones en la resonancia magnética en comparación con los tratados con placebo. En cuanto a la seguridad, los pacientes tratados presentaron una mayor frecuencia de linfopenia, en relación con su mecanismo de acción, y de infecciones por el virus del herpes zóster. Los resultados a largo plazo con ocho años de seguimiento han mostrado que los pacientes tratados no tienen mayor riesgo de desarrollar efectos graves, como neoplasias malignas o infecciones oportunistas. Conclusiones. La cladribina es la primera terapia oral de corta administración que ha demostrado ser eficaz y segura en pacientes con EM recurrente muy activa, y con un efecto sostenido en el tiempo. Las recomendaciones de expertos españoles sobre su manejo suponen un complemento fundamental a las consideraciones descritas por las agencias reguladoras

Introduction: Cladribine is a prodrug, a synthetic analogue of deoxyadenosine, approved for use as selective immune reconstitution therapy in very active recurring multiple sclerosis in adults. Aims: To review the development of the drug, its mechanism of action and the efficacy and safety data obtained to date, as well as to establish recommendations of Spanish experts for its use in clinical practice. Development: The treatment of multiple sclerosis has been simplified with cladribine tablets, and two short courses of administration for two consecutive years (maximum 20 days) are needed to maintain an efficacy of up to four years after the first dose. Results of clinical trials have demonstrated the safety, tolerability and long-term efficacy of cladribine tablets in patients with recurring multiple sclerosis. Thus, patients treated with cladribine presented a significant reduction in the rate of flare-ups, in the risk of disability progression and in the development of new lesions in magnetic resonance imaging compared to those treated with placebo. In terms of safety, the treated patients had a higher frequency of lymphopenia, in relation to its mechanism of action, and of infections by herpes zoster virus. Long-term results with eight years’ follow-up have shown that treated patients are not at greater risk of developing serious events, such as malignant neoplasms or opportunistic infections. Conclusions: Cladribine is the first short-course oral therapy that has been shown to be effective and safe in patients with very active recurring multiple sclerosis, and with a sustained effect over time. The recommendations of Spanish experts on its usage are a fundamental complement to the considerations described by the regulatory agencies