Stamp fabrication by step and stamp nanoprinting

The nanoimprinting is a potential method for submicron scale patterning for various applications, for example, electric, photonic and optical devices. The patterns are created by mechanical deformation of imprint resist using a patterned imprinting mold called also a stamp. The bottle-neck for imprint lithography is availability of the stamps with nanometer-scale features, which are typically fabricated by electron beam lithography. Therefore, patterning of a large stamp is time consuming and expensive. Nanoimprint lithography can offer a low cost and a high through-put method to replicate these imprinting molds. In this work, stamp replication process was developed and demonstrated for three different types of imprint molds. Replication relies on sequential patterning method called step and stamp nanoimprint lithography (SSIL). In this method a small master mold is used to pattern large areas sequentially. The fabricated stamps are hard stamps for thermal imprinting, bendable metal stamps for roll embossing and transparent stamps for UV-imprinting. Silicon is a material often used for fabrication of hard stamps for thermal imprinting. Fabrication process of silicon stamps was demonstrated using both the imprinted resist and lift-off process for pattern transfer into silicon. Bendable metal stamp for roll-to-roll application was fabricated using sequential imprinting to fabricate a polymer mold. The polymer mold was used for fabrication of a nickel copy in subsequent electroplating process. Thus fabricated metal stamp was used in a roll-to-roll imprinting process to transfer the patterns onto a CA film successfully. Polymer stamp for UV-imprinting was fabricated by patterning fluorinated polymer templates using sequential imprinting and a silicon stamp. The imprinted polymer stamp was used succesfully for UV-NIL. In the stamp fabrication process the features of the silicon stamp were replicated with good fidelity, retaining the original dimensions in all of three stamp types. The results shows, that the sequential imprinting is as a potential stamp replication method for various applications

Stamp fabrication by step and stamp nanoimprinting

The nanoimprinting is a potential method for submicron scale patterning for various applications, for example, electric, photonic and optical devices. The patterns are created by mechanical deformation of imprint resist using a patterned imprinting mold called also a stamp. The bottle-neck for imprint lithography is availability of the stamps with nanometer-scale features, which are typically fabricated by electron beam lithography. Therefore, patterning of a large stamp is time consuming and expensive. Nanoimprint lithography can offer a low cost and a high through-put method to replicate these imprinting molds. In this work, stamp replication process was developed and demonstrated for three different types of imprint molds. Replication relies on sequential patterning method called step and stamp nanoimprint lithography (SSIL). In this method a small master mold is used to pattern large areas sequentially. The fabricated stamps are hard stamps for thermal imprinting, bendable metal stamps for roll embossing and transparent stamps for UV-imprinting. Silicon is a material often used for fabrication of hard stamps for thermal imprinting. Fabrication process of silicon stamps was demonstrated using both the imprinted resist and lift-off process for pattern transfer into silicon. Bendable metal stamp for roll-to-roll application was fabricated using sequential imprinting to fabricate a polymer mold. The polymer mold was used for fabrication of a nickel copy in subsequent electroplating process. Thus fabricated metal stamp was used in a roll-to-roll imprinting process to transfer the patterns onto a CA film successfully. Polymer stamp for UV-imprinting was fabricated by patterning fluorinated polymer templates using sequential imprinting and a silicon stamp. The imprinted polymer stamp was used succesfully for UV-NIL. In the stamp fabrication process the features of the silicon stamp were replicated with good fidelity, retaining the original dimensions in all of three stamp types. The results shows, that the sequential imprinting is as a potential stamp replication method for various applications

¿Volverán los tiempos del cólera a Colombia?

“La epidemia de cólera morbo, cuyas primeras víctimas cayeron fulminadas en los charcos del mercado, había causado en once semanas la más grande mortandad de nuestra historia (...) En las dos primeras semanas del cólera, el cementerio fue desbordado y no quedó sitio disponible en las iglesias, a pesar de que habían pasado al osario común los restos carcomidos de nuestros próceres sin nombre (...) Desde que se proclamó el bando del cólera, en el alcázar de la guarnición local se disparó un cañonazo cada cuarto de hora, de día y de noche, de acuerdo con la superstición cívica de que la pólvora purificaba el ambiente (...) Cesó de pronto como había empezado y nunca se conoció el número de sus estragos...” “Así describió Gabriel García Márquez el brote de cólera asiático que azotó a Cartagena en en 1849 y que dio muerte a la cuarta parte de su población. Fue éste seguramente el primer episodio de cólera asiático en nuestro país” (1)

Aptitud del suelo para cultivo de mango vallenato en guacoche, departamento del cesar

The ability of the "La Estancia" farm soil in Guacoche, Cesar state, for growing Vallenato mango (Mangifera indica L.) was evaluated. One hectare of soil was sampled with 16 pits to define the modal soil profile and describe its properties. Physicochemical analysis were carried out to disturbed and not disturbed samples from each horizon under the methodology reported in the Manual No. 47 del Instituto Colombiano Agropecuario and the methodology established by the Agustín Codazzi Geographical Institute (ACGI). According to the properties and the guide of Keys to Soil Taxonomy de los Estados Unidos, the soil was classified as a Typic Dystrustepts, sandy loam mixed isohyperthermic, of medium fertility., The soil does not have limitation for salts, sodium, or aluminum; locally the soil has high water tables that can cause root rot and facilitate the loss of fertilizer with edaphic application.Se evaluó la aptitud del suelo de la Finca “La Estancia” ubicada en Guacoche, departamento del Cesar, para el cultivo de mango (Mangifera indica L.) variedad Vallenato. Se muestreó una hectárea de suelo con 16 calicatas para definir el perfil modal del suelo y describir sus propiedades. Se tomaron muestras disturbadas y no disturbadas de cada horizonte para análisis fisicoquímico según Manual No. 47 del Instituto Colombiano Agropecuario y la metodología establecida por el Instituto Geográfico Agustín Codazzi (IGAC). El suelo fue clasificado como un Typic Dystrustepts, arenoso franco mixto isohipertérmico, de mediana fertilidad, según Claves de Taxonomía de Suelos de los Estados Unidos. El suelo no tiene limitaciones por sales, sodio o aluminio; localmente presentan niveles freáticos altos que pueden ocasionar pudrición de la raíz y facilitar la pérdida de fertilizantes con aplicación edáfica