RESULTADOS DE INVESTIGACIONES REALIZADA EN … 2 final 2.pdf · RESULTADOS DE INVESTIGACIONES...

Universidad de Puerto Rico en Humacao Departamento de Física y Electrónica

Segundo Semestre 2004-2005

Número 2

RESULTADOS DE INVESTIGACIONES REALIZADA EN LOS CURSOS FISI 4161-64

Editores: J. C. Cersosimo, Johanna Rivera y Ramón Rivera

Antenna of 64 meter in Diameter. Parkes Radiotelescope. (Ver Página 3) y SEM photo of a microchannel of less than 100µm. ( Ver Página 6)


Número 2

Tabla de Contenido Search for New Evidence of the Galactic Warp. N. Santiago Figueroa. P. Báez Ortiz. Men-tor: J. C. Cersosimo

3

Study of Laser Miling of Sintered LTCC and Quartz Substrates for Microfluidic Applications. M. Pérez. Mentors: R. Furlan, I. Ramos and J. J. Santiago

4

Use of CNC Milling for the Implementation of Microfluidic Devices. R. Díaz. Mentors: R. Furlan

5

Electrospun poly(3-hexylthiophene-2, 5-diyl) fiber field effect transistor. R. González. Mentor: J. Pinto

5

The Effect of Temperature distance on Microchannels Size and Morphology on Low Tempera-ture Co-fired Ceramics. W. Neris. Mentors: I. Ramos, R. Furlan and J.J. Santiago

6

Electrical Characterization of Ultrafine Thin Oxide (Sn)2) Fibers. N. León, G. Figueroa, A. Meléndez Mentors: I. Ramos, R. Furlan, N. Pinto and J. J. Santiago

7

Data on Position and angle of Neglected Binary Stars. I. Rosado, D. Cotto, V. Miranda, D. Centeno, C. Martínez, Mentors: R. Muller, J. C. Cersosimo

8-9

Sealing and Tests of Microfluidic Oscillators implemented in Transparent Substates. J.M. Castillo Colón, J. Paulino Sustache Mentors: R. Furlan, I. Ramos and J. J. Santiago

10

Sistema de Suspensión de Bandas Elásticas en el Moon Buggy. A. Sánchez, I. García, A. Cruz, J.A. Rodríguez, L. Cruz, M. Almodovar; Mentor: A. Ruiz

11

A Radiation-Induced Carcinogenesis Model for a Martian Environment. A. Arenas, Y. Oca-sio Mentor: E. Esteban

12

On the Gravitational Potential Inside an Ellipsoid in Weyl Gravity. C. Avenancio Mentor: E. Esteban

13

Fabricación y Caracterización de Nanotubos por el método CVD. E. Benson-Avillán, E. Cin-trón Sánchez Mentor: C. Guerra-Vela, N. Pinto

14


SEARCH FOR NEW EVIDENCE OF THE GALACTIC WARP

Nitza Santiago Figueroa, Pierre Báez Ortiz

Mentor: Juan C. Cersosimo

The Milky Way is the visible part from the earth of the galactic plane. The galactic disc is a rotation plane disc and it get signifi-cant deflect from the plane. That is the reason why our galaxy has an “S” shape. The utiliza-tion of the ionized hydrogen emissions is used in order to study the feature for this compo-nent.

On March 28 to April 14, 2005, we went to Parkes and use the facilities of the Austra-lian Telescope at Parkes, Australia. We ob-served the distribution of the diffuse ionized gas around the longitude 270° to 288°. This radio-telescope is an antenna of 64 meters of diameter and have one of the most sensitive receiver of the world.

The radio recombination line data ob-tained will be used in order to search if this ga-lactic component is a tracer or not of the galac-tic warp.

Figure 1: Antenna of 64 meter in

diameter.

Parkes Radiotelescope.

We obtain data from 600 positions. They are being analyzed with the karma program at the Humacao observatory facilities.

Figure 2: The multibeam receiver,

wich is composed of 13 beams.

Número 2


STUDY OF LASER MILLING OF SINTERED LTCC AND QUARTZ SUBSTRATES FOR MICROFLUIDIC APPLICATIONS

Miguel Perez Tolentino1

Mentors: Rogerio Furlan1, Idalia Ramos1 and Jorge J. Santiago-Avilés2

1Department of Physics and Electronics, University of Puerto Rico at Humacao

2Department of Electrical and Systems Engineering, University of Pennsylvania

Microchannels with depths of more than 100 µm were obtained in tens of sec-onds for sintered LTCC and quartz sub-strates using thermal laser milling (Universal Laser Systems, 60 W CO2 pulsed laser, wave length of 10.6 µm, focal point diameter of ~ 130 µm). The LTCC substrates (DuPont 951 AT) were annealed in air using the fol-lowing sequence: RT to 300 °C, 10 °/min. + 300 °C, 30 min. + 300 °C to 850 °C, 10 °/min. + 850 °C, 30 min. + cooling to RT. Quartz substrates were microscope slides (United Glass Technologies) 1 mm thick and with an area of 2.5 cm by 7.5 cm. Profilometry and optical microscopy analysis revealed that mi-crochannels milled in quartz substrates re-sulted with deeper features and can easily be fabricated without defects on the bottom (cracks).

These defects, caused by thermal stress were observed for all samples milled in sintered LTCC. Thus, for practi-cal applications the LTCC substrates have to be milled throughout their entire thickness. In the case of the sintered LTCC samples the laser machining also caused chemical changes, as the color of the surface changed from blue to black. X-Ray Photoelectron Spectros-copy (XPS) results show an increase of the carbon concentration after laser mill-ing confirming that the black color is as-sociated with organic residues resulting from pyrolysis/oxidation. We also con-cluded that the removal of material (evaporation and melt expulsion) in the raster direction and perpendicularly to it is not uniform.

A full paper with the results of this investigation has been accepted in the 19th National Conference on Undergraduate Research”, (NCUR) 2005, Lexington, Virginia. This work has been supported by the National Science Foundation, grant No. NSF-DMR-0353730.

Número 2


ELECTROSPUN POLY(3-HEXYLTHIOPHENE-2,5-DIYL) FIBER FIELD EFFECT TRANSISTOR

Rosana González Mentor: Nicholas Pinto

Department of Physics and Electronics

One of the ways to reduce the size and increase component density in circuits is via the fabrication of devices based on semiconductor nanofibers. We report on the fabrication of an electrospun regio-regular poly(3-hexylthiophene-2,5-diyl) fiber field effect transistor (FET). The hole mobility of the device was calculated to be 4 x 10-4 cm2/V-s and the ON/OFF ratio was ~7.

The results are compared to those obtained on a thin film FET. The large surface to vol-ume ratio of the fiber makes it susceptible to doping, however, proper handling in an inert environment and pretreatment of the sub-strates should enhance device performance. Electrospinning is proposed as an easy one step process to fabricate one-dimensional polymer FET’s.

USE OF CNC MILLING FOR THE IMPLEMENTATION OF MICROFLUIDIC DEVICES

In this work we are using a CNC machine to de-fine microchannels in LTCC (Low Temperature Co-Fired Ceramics) tapes. The tapes are being machined in their green form, i.e., before sinter-ing. The activities include to define microchan-nel patterns using a software package that comes with the CNC, to analyze the obtained

microchannels as a function of width and depth using a profilometer and to find out process conditions (speed, feed speed, etc.) to obtain channels with widths of hundreds of micrometers.

Ramón Díaz Martínez Mentor: Rogerio Furlan

Department of Physics and Electronics

Número 2


Número 2

THE EFFECT OF TEMPERATURE AND DISTANCE ON MICROCHANNELS SIZE AND MORPHOLOGY ON LOW TEMPERATURE CO-FIRED CERAMICS

William Neris

The objective of this work is to have a better understanding of Jet Vapor Etch-ing in LTCC by study some variables that affect the morphology. . A homemade Jet Vapor Etching (JVE) system was used to produce the micro-channels on the LTCC. In the JVE a jet of acetone vapor emerges through a glass nozzle and impinges on the LTCC, removing the composite material and producing differ-ent structures. The morphology of the structure is a function of the acetone temperature and pressure, the nozzle shape, and the distance between the nozzle and the sample. The LTCC sam-ple is positioned on a sample holder on a computer-controlled XYZ station. Under-standing these parameters will help us obtain channels of smaller diameters and with smoother edges. This method could be used as an economical process for the fabrication of microchannels. The channels produced with LTCC are later sintered at 700, 800, 900ºC. The size and morphology of the microchannels are characterized using optical micros-copy, scanning electron microscopy (SEM), and profilometry.

We found that by increasing the temperature and decreasing the distance between the nozzle and the sample, a noticeable decrement in diameter was obtained for the microchannels in LTCC. Mi-crochannels of less than 100µm have been ob-tained in this way. This procedure shows great advantages over other methods as there is no limitation in the diameter of the channels. JVE however still shows some limitations in controlling the channels morphology. Other parameters such as angle between jet and sample and chemical reagent, are still to be explored which could greatly improve the JVE process.

Figure 1: SEM photo of a microchannel of less than 100µm. By adjusting the distance to be as close as possible to the nozzle (approx. 250µm), and adjusting the tempera-ture between 50 ºC to 60 ºC, smaller channels have been obtained.

Publications: Proceedings NCUR 2005

Mentors : Idalia Ramos1, Rogerio Furlan1, Jorge J. Santiago Avilés2


2Department of Electrical and Systems Engineering, University of Pennsylvania

RESULTADOS DE INVESTIGACIONES

REALIZADA EN LOS CURSOS FISI 4161-64

ELECTRICAL CHARACTERIZATION OF ULTRAFINE TIN OXIDE (SNO2) FIBERS

Neliza León, Glendalys Figueroa, Anamaris Meléndez Mentors: Idalia Ramos, Rogerio Furlan, Nicholas Pinto, Jorge J. Santiago Avilés

In previous work ultrafine tin oxide fibers in the rutile structure, with diameters ranging from 60nm to several microns, were synthesized using electrospinning and metallorganic decomposition tech-niques. In this work we use a precursor solution which is a mixture of a pure SnO2 sol made from SnCl4 : H2O : C3H7OH : 2-C3H7OH at a molar ratio of 1:9:9:6, and a viscous solution made from poly(ethylene oxide) (PEO) (molecular weight 900,000) and chloro-form CHCl3 at a ratio of 200mg PEO/10mL CHCl3. This solution allows obtaining an appropriate viscosity for the electrospinning process. The as de-posited fibers were sintered at 400, 500, 600, 700 and 800°C in air for two hours. Previous results using this method and characterizing the fibers with scanning electron microscopy (SEM), x-ray dif-fraction (XRD), Raman microspectrome-try and x-ray photoelectron spectros-copy (XPS) showed that up to the sin-tering temperature of 700°C, the synthe-sized fibers are composed of SnO2. Further analysis using SEM and I/V characteristics were done this semes-ter.. The results show that the fibers are composed of tin oxide and that smooth and continuous fibers in different shapes (straight, curved, ribbon-like, and spring-like) can be obtained using this method. The samples change in resistivity as a function of the annealing temperature can be attributed to the thermally activated formation of a nearly stoichoimetric solid.

SEM images of SnO2 fibers

a) segment of straight fiber,

b) ) spring-like fiber.

Sintering temperature (°C)

300 400 500 600 700 800 900

Res

istiv

ity(1

02 Ω− c

m)

0.1

1

10

100

1000

Resistivity of tin oxide fibers sintered for two hours at

400, 500, 600, 700, and 800°C in air.

Publications: Proceedings NCUR 2005, Proceedings SPIE 2005

Número 2


Número 2

DATA ON POSITION AND ANGLE OF NEGLECTED BINARY STARS

I. Rosado, D. Cotto, V. Miranda, D. Centeno ,C. Martínez Mentors: R.J. Muller, J.C. Cersosimo

We study angle/position of binary stars. Our data is obtained at the NURO Observatory located at Anderson Mesa in Flagstaff, Arizona. We go there twice a year (May and October) to take images of binary stars (standard and neglected) with a CCD camera attached to the telescope.

Figure 1: Kappa Herculis (STF 2010 AB)

The process of analysis starts by taking the negative of each photo (figure 2). Then, we enlarge them so we could see the pixels. Counting the pixels is our way to determine the separation between the stars. We also measure the angle of separation between the stars (figure3).

The way the CCD camera is inserted to the telescope produces images with north down and east to the left. How-ever, as the images migrate to the win-dows environment (images processing programs), pixel 1.1 changes from down and to left (Unix) to up and to the left (Windows) and all the images presented here have north up and east to the left. There is a systematic error introduced by the uncertainty with which the CCD the deviates from perfectly level when set in the telescope, and this introduces an un-certainty in the angle measurement of the binary. To correct this “offset error” each observing run includes the acquisi-tion of images of “standard” binaries, well known binaries that are used to calculate the offset error. It is, afterward included in the angle calculation of binaries. Our targets are binary stars that have been neglected for many years and are included in the Washington Double Stars Catalog of Neglected Binaries pro-duced by Dr. Brian Marsen and his col-leagues of the U.S. Naval Observatory.

Figure 2: Kappa Herculis

(Inverted)

Figure 3: Measure-ment of the position angle and separation of Kappa Herculis


Número 2

Table I shows the results for a “standard binary star”.

Table I

Kappa Herculis R.A. 16 08.1 DEC +17

UPR Date

# Im-age

WDS RHO

UPR RHO

WDS θ

UPR θ UPR Offset

May2001

0107 28 28 12 12.3 0.3

Apr2003

0079 27.5 27.7 13 12.8 0.8

May2004

0069 27.5 27.5 13 14 -3

Oct2004

0035 27.4 27 13 13.5 0.5

Table II. Shows the results for selected “neglected binary star”.

ES 627 R.A. 16 18 36 DEC +51 20

UPR Date

# Im-age

WDS Date

WDS RHO

UPR RHO

WDS θ

UPR θ UPR Offset

1903 12 286

1933 12 288

May2002 0050 2002 11.6 12.4 287 288.4 2.4

Apr2003 0082 2002 11.6 11.8 287 287.8 0.8

May2004 0071 2003 11.8 12 288 287 -3

Oct2004 0031 2003 11.8 12 288 285.5 0.5

This data helps astronomers all around the world to determine if some stars are visual bi-nary stars or physical. Some of the neglected ones (last measured almost a hundred years ago) appear to be visual binary stars and our results will help eliminate them from the list of binary stars. We thank the Puerto Rico Space Grant Consortium (NASA) and the Puerto Rico Alliance for Minority Participation (LSAMP) for their support of this project. We also thank Lowell Observa-tory for their support. Last but not least we want to thank NURO technician Ed Anderson for his tireless efforts that make these projects successful.


SEALING AND TESTS OF MICROFLUIDIC OSCILLATORS IMPLEMENTED IN TRANSPARENT SUBSTRATES

Jose Manuel Castillo Colon1 and Josean Paulino Sustache1

Mentors: Rogerio Furlan1, Idalia Ramos1 and Jorge J. Santiago-Avilés2


In this stage of this project we con-firmed that microchannels defined in quartz substrates, that are part of a mi-crofluidic oscillator structures, can be hermetically sealed using thermal adhe-sive (Monokote ®, Hobbico Inc., trans-parent, tensile strength 25,000 PSI, thickness of ~ 100 µm). In order to ob-tain a uniform adhesion, the substrates have to be heated to a temperature of 105 °C, using a hot plate. After reach-ing this temperature the adhesive is manually pressed on the substrate us-ing a metallic block. The sealing was investigated by injecting a contrast fluid composed of mixtures with different pro-portions of distilled water and colloidal dispersion of graphite particles (Aquadag® E, Water-Based Colloidal Graphite Resistance Coating).

The internal flow was observed by op-tical microscopy. Attempts to observe internal oscillation as a function of the input flow did not show positive results so far. We observed a non symmetri-cal distribution of flow internally to the device, with most of the flow leaving from one only output. We will address this issue with more detail in the next stage of the work, and evaluate input interconnections with plastic tubes of different internal diameters and also, we will verify if blocking one of the out-puts of the oscillator we can force the occurrence of oscillations. This work was presented in the 40th ACS Junior Technical Meeting, Mayaguez, PR, 2005, p. 30 of the book of abstracts. This work has been sup-ported by the National Science Foun-dation, grant No. NSF-DMR-0353730.

Número 2


Sistema de Suspensión de Bandas Elásticas en el Moon Buggy

Sánchez A., García, I., Cruz, A., Rodríguez, J.A., Cruz, L.R. y Almodóvar, M. Mentor: Abraham Ruiz

Uno de los factores que determinan en des-empeño y de los carros en el “Moon Buggy Race” es el peso y el sistema de suspensión. El problema es que un buen sistema de sus-pensión agrega peso y partes móviles. Para mejorar este problema implementamos un sistema de suspensión simple e innovador, el cual consiste básicamente, en colgar el peso del carro de los 4 ejes mediante bandas elás-ticas que a su ves se fijan chasis vía dos tu-bos de soporte. Vea la figura a continuación.

Los impactos en las ruedas son absorbidos por la bandas elásticas que se deforman y estiran despegándose del tubo de soporte. El chasis y los tripulantes quedan aislados de los choques. Para que el sistema funcio-ne como amortiguador la banda se hace en-rollando decenas de veces una banda fina de caucho. Cundo el sistema se deforma por el impacto se produce fricción entre las vueltas individuales disipando la energía mecánica. De esa manera tenemos un sis-tema de suspensión independiente en las 4 ruedas muy simple y funcional que a su ves abarata la construcción del carro sin debili-tarlo mecánicamente.

Otra virtud de este sistema es que permite la reducción de peso al poder reducir el nu-mero de partes móviles. Así quedo demos-trado este año. Nuestro carro fue el mas simple y liviano de la competencia. Solo 85 libras. Esto generó gran expectación debido a que su apariencia frágil hizo pensar a mu-chos que no resistirá la ruta. Sin embargo, un carro puede ser fuerte y liviano a la ves si colocas las cargas y dirigir los impactos hacia los puntos fuertes que es en este ca-so el sistema de amortiguamiento. A la hora del recorrido todos los ojos estaban puesto sobre nuestro carro. Esta era la prueba de fuego. El buggy recorrido la ruta de forma excelente. Llegó a la meta con el segundo mejor tiempo de la tarde, sin penalidades y sin averías. Luego de esto muchos integran-tes de equipos fueron a fotografiar en deta-lle el sistema de suspensión de bandas elásticas. El año entrante veremos algunos buggys con este sistema.

Número 2


A Radiation-Induced Carcinogenesis Model for a Martian Environment

E. P. Esteban*,+

A. Arenas#

Y. Ocasio* *Department of Physics and Electronics, UPRH

#Department of Biology, UPRH

We have developed a mathematical n-stage carcinogenesis model with 3n+8 parameters characterizing different biological processes arising when a stem cell population is con-tinuously irradiated with high-LET HZE ra-diation. This multi-step model is mathemati-cally described by a set of n+4 first order lin-ear differential equations, and assumes "n" possible mutations before a normal cell be-comes a cancerous cell. At any time t, we present exact closed form solutions describing different irradiated stem cell populations for any given "n" mutations. The case for n=1 and n=2 mutations is ex-plicitly written down. It is also proved that if mutant populations are considered the sur-vival fraction as defined by Target theory must be modified

Finally, we solve the proposed model were is more plausible to occur, i.e. in deep space, where Earth's magnetic shield and atmosphere can not longer shield us from galactic cosmic rays and special particle events. In fact, by using data obtained by MARIE (a satellite orbiting Mars) we have estimated astronauts’ survival curves. This work was presented in the “Día de la Investigación” and the PRISMA meeting held at the University of Puerto Rico-Mayaguez. For a more detailed version of our work please go to the following link.

Número 2

RESULTADOS DE INVESTIGACIONES REALIZADA EN LOS CURSOS FISI 4161-64 Número 2

On the Gravitational Potential Inside an Ellipsoid in Weyl Gravity

E. P. Esteban*,+

C. Avenancio&

&Department of Mathematics, UPRH *Department of Physics and Electronics, UPRH

By extending Chandrasekhar's procedures from Newtonian gravity to Weyl gravity we have obtained a closed form analytical so-lution for the gravitational potential inside a homogeneous triaxial ellipsoid. This non-Newtonian gravitational theory predicts the existence in the gravitational potential of linear and quadratic terms, in addition of the very well known ~1/r term. By using a procedure given in an earlier work by S. Vazquez and E. Esteban, we have verified that in fact, the gravitational potential (Φl) due to the linear term is given by Φl = πργ (C1x+C2y+C3z+ C4x²y²+ C5x²z²+ C6y²z² + C7x²+ C8y²+ C9z²+ C10),

where ρ is the density, γ is a dimensional constant, and the Ci's are constants written in terms of elliptical integrals. We also found that in the case of a triaxial ellipsoid, the quadratic term does not contribute to the Weyl gravitational potential. This work was presented in the “Día de la Investigación” and the PRISMA meeting held at the University of Puerto Rico-Mayaguez. A detailed version of this work can be found in the following link.

Número 2 RESULTADOS DE INVESTIGACIONES REALIZADA EN LOS CURSOS FISI 4161-64

FABRICACIÓN Y CARACTERIZACIÓN DE NANOTUBOS POR EL MÉTODO CVD

Benson-Avillán, Elixia M.* , Cintrón Sánchez, Ednaida I, Mentor: Guerra-Vela, Dr. Claudio, Pinto, Dr. Nicholas

En los últimos años se ha desarrollado la idea de crear nanotecnología con el propó-sito esencial de llevar la miniaturización de los componentes electrónicos integrados a niveles mayores. Uno de los elementos más prometedores en este proceso es el nanotu-bo de carbono cuyo diámetro es de unos 3nm. La posibilidad de desarrollar una tec-nología con nanotubos parece ser real y promete transformar la vida de todos noso-tros más allá de la electrónica. Como institu-ción educativa de frontera el Departamento de Física de la UPRH ha desarrollado un proyecto de producción y caracterización de nanotubos de carbono por el método CVD (Chemical Vapor Deposition), en un esfuer-zo por integrar a sus estudiantes en las corrientes de progreso científico más importantes en el mundo.

En esta presentación explicaremos el pro-yecto y mostraremos fotografías de los nano-tubos producidos, así como los resultados de los procesos de caracterización hechos por nosotros. Patrocinado por NSF-NUE Integra-tion of Nanoscience into the Undergraduate Curriculum: From Fabrication to Practical Aplication of Nanodevices Propo-sal#0407137). Para mayor información visite nuestra página http://cuhwww.upr.clu.edu/~nsfnue/.

Proyectos Auspiciadores: 1. Puerto Rico Space Grant Consortium (NASA) 2. Puerto Rico Alliance for Minority Participation (LSAMP 3. NSF - Penn-UPR Partnership for Research and Education in Materials (DMR-0353730) - Advance Institutional Transformation (SBE– 0123654) - Research in Undergraduate Institution ( RUI) 4. ACS-PRF American Chemical Society Petroleum Research

Fund 5. UPRH– FOPI

Universidad de Puerto Rico Departamento de Física y Electrónica Estación Postal CUH 100 CARR 908

Humacao PR 00767-4300 www.uprh.edu/~física, jo_rivera@ webmail.uprh.edu

Tel. 787-850-9381-9344 Fax: 787-850-9308

Nota de los editores

La inclusión de la investigación y la labor creativa son fundamentales para el

desarrollo integral de los estudios subgraduados. Los miembros del Depar-

tamento de Física y Electrónica reconocen la importancia de estos elemen-

tos como parte fundamental de la labor académica. La aplicación del conoci-

miento en la búsqueda de nuevas verdades y la interpretación del mundo

que nos rodea, permite el desarrollo del pensamiento crítico; es una herra-

mienta académica innovadora para motivar y satisfacer la curiosidad intelec-

tual del los/las estudiantes. Además contribuye al desarrollo social y cultural

agilizando la inserción en el ciclo económico de Puerto Rico y del mundo.

La inmersión de estudiantes en investigación subgraduada se hace desde

los inicios del programa de Bachillerato de Física Aplicada a la Electrónica,

en 1987, mediante el ofrecimiento del curso Investigación Subgraduada

(FISI 4161). La usual contratación de Profesores con peritaje en investiga-

ción capturó el interés de los estudiantes de Bachillerato para involucrarse

en tan digna tarea. El esmero y dedicación de los profesores ayudó a ellos

mismos a trasformar las técnicas de enseñanza debido al desafío que impli-

ca investigar y formar a estudiantes en la disciplina.

La consecuencia de estos esfuerzos condujo a aumentar el ofrecimiento

debido al interés de los estudiantes en hacer investigación. En consecuen-

cia se atendió la demanda de los estudiantes incluyendo los curso de Inves-

tigación Subgraduada (FISI 4162 FISI 4163 y FISI 4164). Los cuatro cursos

mencionados se ofrecen regularmente desde agosto de 1993. El compromi-

so permitió a la academia refinar las estrategias de enseñanza-aprendizaje,

que en esencia son el modelo tomado por el constructivismo, el método de

prueba y error.

Después de diecisiete años de esfuerzo el Departamento cuenta con una

decena de profesores que escriben propuestas, consiguen fondos externos

y hacen presentaciones en reuniones internacionales de ciencia, y publican

periódicamente en revistas de circulación internacional. En el departamento

hay dos laboratorios dedicados a la investigación y un laboratorio de ins-

trucción equipado con instrumentos de primera línea en el que se ofrecen

dos cursos de concentración.

Vale destacar el compromiso de la Institución (UPRH) que hace posible la

investigación subgraduada, es por ello que me complace reconocer a las

diferentes administraciones que están y han colaborando en este esfuer-

zo. El reconocimiento es también extendido a los profesores por la labor de

adiestramiento a los estudiantes. La revista de investigación subgraduada

fue concebida para que sea un instrumento administrativo que permita la

visibilidad de esta actividad, pero además es un documento dirigido a los

estudiantes, profesores y la comunidad científica de Puerto Rico, con el

propósito de divulgar las actividades académicas que han sido pioneras en

el Sistemas UPR junto con otros Recintos. Este instrumento estará además

disponible en la Internet para permitir el acceso a todas las comunidades.

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