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Gurabo, Puerto Rico

Universidad del Turabo is a private, non-profit, and secular university system in Puerto Rico. Wikipedia.

Quinones P.D.,University of Michigan | Carbajal G.J.,University of Turabo
International Journal of Heat and Mass Transfer

Flow boiling heat transfer under microgravity conditions can be extended and enhanced by means of using porous stacks, or capillary columns, arranged on top of a flat heated surface. Under these conditions, body forces are negligible to remove the generated vapor away from the hot surface, which eventually hinders liquid from reaching it. It is possible to increase the critical heat flux (CHF) by having porous stacks symmetrically arranged on this surface; which draws the liquid phase towards it by means of capillary forces. Various flow regimes in the capillary enhanced surface flow boiling can be identified. These include: the regime where the liquid is supplied between the columns, the regime where the liquid flow is controlled by liquid capturing and the viscous drag-capillarity in the columns, and the critical heat flux. For the theoretical model, the expression for the interfacial lift-off model critical heat flux was interpreted based on customizable parameters instead of those imposed by the physics of the flow. This study indicates a potential improvement in CHF by having an inter-column spacing smaller than the critical wavelength for a plain surface. There is also a potential benefit of having the wetting contact to wavelength ratio to be larger than the constant of 0.2 found in experimental studies. The CHF regime can occur by a limitation of the stacks to have access to the liquid phase, as it happens when they are completely submerged in a vapor phase, or by reaching the maximum capillary pressure drop in the stack (as per the Darcy-Ergun momentum equation), or by reaching an entrainment limit of the vapor flow passed the capillary columns. Therefore the critical heat flux can also be extended as long as the capillary columns protrude over the vapor layer and their viscous capillary and entrainment limits are not reached. © 2011 Elsevier Ltd. All rights reserved. Source

Bhattacharyya P.,University of Turabo | Bishayee A.,Signal Sciences
Anti-Cancer Drugs

Ocimum sanctum Linn., commonly known as 'Tulsi' or 'Holy Basil', is considered to be the most sacred herb of India. Several anatomical parts of O. sanctum are known to have an impressive number of therapeutic properties and accordingly find use in several traditional systems of medicine, such as Ayurveda, Unani, and Siddha. Scientific investigations have shown that O. sanctum has a plethora of biological and pharmacological activities. The presence of an impressive number of phytoconstituents in O. sanctum could explain its exceptional beneficial effects. Although several recent articles provide an overview of the various pharmacological properties of O. sanctum, the use of this herb for either prevention or therapy of oncologic diseases has not been exclusively and critically discussed in the literature. The present review critically and comprehensively examines the current knowledge on the chemopreventive and therapeutic potential of O. sanctum. The review also examines, in detail, the biochemical and molecular mechanisms involved in the antineoplastic effects of O. sanctum. Finally, we discuss the role of synergy, current limitations, and future directions of research toward the effective use of this ethnomedicinal plant for the prevention and treatment of human cancer. © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins. Source

Chang J.H.,Massachusetts Institute of Technology | Aleman De Leon C.R.,University of Turabo | Hunter I.W.,Massachusetts Institute of Technology

A simple, novel method of synthesizing self-assembled, nanostructured conducting polymer films has been developed. Applying an increased centrifugal force on the electrodes during the electrochemical deposition process yields high surface area, micro- or nanostructured polymer films. Scanning electron microscopy showed that as the applied g-force increased, the polymers progressed from having smooth, "cauliflower" morphologies, to intermediate microstructured surfaces, to finally dense nanostructured surfaces with pore sizes as small as 50 nm. Cyclic voltammetry revealed that films grown at higher centrifugal accelerations (higher than 500g) exhibited less degradation after electrochemical cycling and more capacitive behavior. © 2012 American Chemical Society. Source

Lodge D.J.,U.S. Department of Agriculture | Cantrell S.A.,University of Turabo | Gonzalez G.,U.S. Department of Agriculture
Forest Ecology and Management

Fungi are important for maintaining fast rates of decomposition in low quality tropical leaf litter via immobilization and translocation of limiting nutrients from sources to sinks and conserving nutrients after disturbance. Tropical trees often have low nutrient to carbon ratios. Disturbances such as hurricanes and logging transfer a large mass of green leaves with high nutrient concentrations to the forest floor, but the associated opening of the canopy dries the litter, inhibiting basidiomycete fungi that play critical roles in lignin degradation and nutrient conservation. We conducted a replicated block factorial experiment designed to disentangle the individual and interactive effects of canopy opening and green debris deposition on phosphorus (P) content, mass loss and fungal connectivity in decomposing leaf cohorts in subtropical wet forest in the Luquillo Mountains of Puerto Rico. Though green leaves had higher P concentrations they did not decompose significantly faster than senesced leaves. Mass loss differed among treatments after 14, 40.5 and 53. weeks decomposition. Mass loss at 7. weeks was predicted by P concentration at 7. weeks; mass loss in senesced leaves at 14. weeks was predicted by abundance of fungal connections between the senesced litter cohort and forest floor at 7. weeks. Fungal connectivity and P accumulation at 7. weeks and mass loss of senesced leaves beginning at 14. weeks were significantly different from and lower in plots with trimmed canopy and no debris than in the untrimmed plots with debris. Litter moisture was previously found to be significantly lower under open than closed canopy, and we found that moisture was a significant predictor of fungal connectivity in both senesced and green leaves. Deposition of green leaves ameliorated the inhibitory effect of canopy opening on fungal connectivity between litter cohorts by retaining moisture; consequently fungal connectivity and mass loss in senescent leaves did not differ between the Trim. +. Debris and the control treatments. Phosphorus content of senesced leaves increased significantly by 7. weeks in both trimmed and untrimmed plots with added green debris and in the control plots. Based on mass balance calculations, both the underlying forest floor and overlying green leaves likely contributed P to the decomposing senesced leaf cohort. Fungal translocation of P through hyphal connections between litter cohorts explains some of the changes in P content. Though fungi were important in conserving P, most of the P that was likely leached from green leaves was not retained in the litter layer. © 2014. Source

Agency: NSF | Branch: Standard Grant | Program: | Phase: | Award Amount: 117.43K | Year: 2013

With this award from the Chemistry Major Research Instrumentation Program, Professor Rolando Roque-Malherbe from Universidad Del Turabo and colleagues Agustin Rios, Anastacio Emiliano and Cesar Lozano will acquire an automatic high pressure physisorption analyzer. The proposal is aimed at enhancing research and education at all levels, especially in areas such as (a) metal organic frameworks for methane storage; (b) Prussian blue analogues for small molecules separation from gas flows; and (c) pore size augmented nitroprussides for carbon dioxide storage.

A high pressure physisorption analyzer takes advantage of the very weak attractive interactions between molecules, which arise from so-called van der Waals interactions. In general, high pressure is applied to a gas in contact with a solid substrate. As the pressure increases, the gas molecules are attracted to various degrees by the substrate. Under appropriate conditions, these weak interactions allow separation of gases. If additionally the pores of the substrate are manipulated, the interactions may increase and such solids may be used to store gases. Useful examples are those of carbon dioxide, which may contribute to global warming and may serve as feedstock for chemical reactions under concentrated conditions.

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