Metropolitan University of Puerto Rico

San Juan, Puerto Rico

Metropolitan University of Puerto Rico

San Juan, Puerto Rico
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Yue X.,Wuhan University of Technology | Friedman J.S.,Metropolitan University of Puerto Rico | Wu X.,Wuhan University of Technology | Zhou Q.H.,Miami University Ohio
Journal of Geophysical Research: Atmospheres | Year: 2017

We present the seasonal variations of the nocturnal mesospheric potassium (K) layer at Arecibo, Puerto Rico (18.35°N, 66.75°W) from 160 nights of K Doppler lidar observations between December 2003 and January 2010, during which the solar activity is mostly low. The background temperature is also measured simultaneously by the lidar and shows a strong semiannual oscillation with maxima occurring during equinoxes at all altitudes. The annual mean K density profile is approximately Gaussian with a peak altitude of 91.7 km. The K column abundance and the centroid height have strong semiannual variations, with maxima at the solstices. Both parameters are negatively correlated to the mean background temperature with a correlation coefficient < -0.5. The root-mean-square (RMS) width has a distinct annual oscillation with the largest width occurring in May. The seasonal variation of the centroid height is similar to that of the Fe layer at the same site. The seasonal temperature variation indicates significant enhanced wave-induced downward transport for both species during spring and autumn. This explains the metal layer centroid height and column abundance variations at Arecibo and provides a general mechanism to account for the seasonal variations in the centroid height of all metal species measured at low-latitude and midlatitude sites. © 2017. American Geophysical Union. All Rights Reserved.

Rosado-Berrios C.A.,Metropolitan University of Puerto Rico | Velez C.,Metropolitan University of Puerto Rico | Zayas B.,Metropolitan University of Puerto Rico
Toxicology in Vitro | Year: 2011

Phthalates are ubiquitous compounds used in the manufacturing industry. Some are known endocrine disruptors, acting as xenoestrogens, others induce reproductive toxicity and damage to DNA among other effects. Studies on apoptosis induction and mitochondrial damage capacity of phthalates on the immune system are limited. This study aims to determine cell viability inhibition and apoptosis induction of diethylhexyl phthalate (DEHP) and monoethylhexyl phthalate (MEHP) on the human TK6 lymphoblast cell line at concentrations found in the environment. Key hallmark events, such as mitochondrial membrane permeability, generation of reactive oxygen species (ROS) and activation of caspase 3 and 7 were measured. Concentrations that inhibit viability of 50% (IC 50) of the cells were determined at 24, 48 and 72h with doses ranging from 10 to 500μM. Changes in mitochondrial membrane permeability, ROS generation and activation of caspases 3 and 7, were measured as part of the cell death mechanism. The IC 50 at 24h was approximately 250μM for both phthalates; at 48h were 234 and 196μM for DEHP and MEHP, respectively and at 72h IC 50s were 100 and 80μM for DEHP and MEHP, respectively. Overall the longer the time of exposure the lower the IC 50's for both compounds. Both compounds affected mitochondrial membrane potential, promoted ROS generation and activated caspases 3 and 7. MEHP is more toxic, promotes higher level of ROS production and caspases activation. Our findings suggest that DEHP and MEHP have the capacity to induce apoptosis in cells of the immune system at concentrations found in the environment. © 2011 Elsevier Ltd.

Miranda M.T.,Metropolitan University of Puerto Rico
Boletín de la Asociación Médica de Puerto Rico | Year: 2013

Multiple Sclerosis (MS) is a complex disease where genetic and environmental factors have been implicated. The onset of symptoms occurs in individuals from twenty to fifty years of age, producing a progressive impairment of motor, sensory and cognitive functions. MS is more frequent in females than in males with a ratio of 4:1. The prevalence of the MS varies among ethnics groups such as Europeans, Africans and Caucasians. The estimated prevalence of MS in Puerto Rico is 42 for each 100,000 habitants, which is more than the prevalence reported for Central America and the Caribbean. In spite of this prevalence, the genetic component of MS has not been explored in order to know the alleles' expression of Puerto Rican MS patients and compare it with the allele expression in other ethnic groups. Thirty-five patients and 31 control subjects were genotyped. The allele frequencies expressed in this sample were similar to those expressed for Puerto Ricans in the National Marrow Donor Program Registry (n = 3,149). The most prevalent alleles for MS patients were HLA-DRB1*01 and *03. HLA-DQB1*04 was the most frequent in the control group and HLA-A*30, in MS patients. These findings are in agreement with published data. HLA-DQB1*04 was a marginal protector in this sample and this role has not been described before. The accuracy of the results is limited due to the sample size. After performing a statistical power analysis it showed that by increasing the sample the values would be significant.

Galan J.G.,Metropolitan University of Puerto Rico
European Journal of Science and Theology | Year: 2015

In this article we offer an analysis of the practical and theoretical paradigm of media education as a fundamental pedagogical model for the adequate development of the current methods of digital literacy. In a society dominated by the flow of information and communicative processes-in which digitalization has led to techno-media convergence, the complete uniting of ICT novelties and traditional media-it is essential to use all the vast experience of basic principles, pedagogical theories and practice which this educational paradigm has offered during decades. The current techno-media society is not an altruistic system; the communicative processes continue to be dominated by economic, political and social elites whose main interest is to influence and control the population. In this context-conceiving education as the only way to achieve the full and democratic development of our society, for its growth in values and solidarity-an analysis of reality starting in school is essential by forming a citizenship conscious of the power and influence of the ICT and its true meaning in the world. An authentic digital literacy should include the correct understanding of the new techno-media languages, and cannot simply be reduced to a formation of a technical and instrumental kind. © 2015, European Journal of Science and Theology. All right reserved.

Galan J.G.,Metropolitan University of Puerto Rico
European Journal of Science and Theology | Year: 2015

Chronological and historical time must be present in the instructive processes for its comprehension is fundamental to the education of human beings. Otherwise, the teaching of Social sciences and Humanities at all its academic levels would be impossible. This article has as its principal objective the establishment of a new theoretical framework about the characteristics of the study of time in education. It is defended that the appearance of the social digital offers new mediums and resources that are taking us towards the creation of innovative didactic models in which teaching and the construction of the sense of historical time can be improved considerably. This fact requires an important revision of the current educative theories related to the teaching of time. As the main conclusion, it was established the need for deepening the study of this important problematic in the light of the methodologies used today in the field of digital technologies and in the context of the media education. The development of the understanding of historical and chronological time, independent of cognitive development of the person, must be understood above all as an educative process in which strategies and mediums employed are fundamental. © 2015, Ecozone, OAIMDD. All rights reserved.

Bacelo D.E.,Metropolitan University of Puerto Rico | Bacelo D.E.,National University of Patagonia San Juan Bosco | Binning Jr. R.C.,Metropolitan University of Puerto Rico
Chemical Physics Letters | Year: 2011

Density functional theory calculations, in both the high-spin and broken symmetry approximations, have been conducted on models of the diiron(II) ferroxidase complex of human H ferritin. Initial configurations were chosen from previous experimental and theoretical structures of the dizinc complex. The diiron complexes show no significant deviation in ligand or metal positions from the corresponding dizinc complexes, even maintaining similar structures through an extensive reorganization, and thus the often-made assumption of homology between Fe(II) and Zn(II) is supported. Geometry differences between diiron complexes calculated in the high-spin and broken symmetry approximations are also found to be minor. © 2011 Elsevier B.V. All rights reserved.

Kandi S.K.,University of Delhi | Manohar S.,University of Delhi | Velez Gerena C.E.,Metropolitan University of Puerto Rico | Zayas B.,Metropolitan University of Puerto Rico | And 2 more authors.
New Journal of Chemistry | Year: 2015

The privileged scaffolds of curcumin and 4-aminoquinolines are extensively used in the design and synthesis of biodynamic agents having remarkable efficacy against diseases like cancer and malaria. Therefore, we anticipated that covalent hybridization of these two pharmacophores via the triazole linker may lead to molecules with better anticancer activity. The synthesized hybrid compounds were tested for their anti-cancer activity on 60 human cancer cell lines, which represent diverse histologies. Our study has identified a set of these hybrids that showed excellent growth inhibition at nano-molar concentrations. The mechanistic investigations through a series of assays showed apoptotic induction as a cause for their displayed anticancer activity. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015.

Galan J.G.,Metropolitan University of Puerto Rico
European Journal of Science and Theology | Year: 2016

In the present article the necessity of introducing the teaching of time from the first educative stages is defended through a didactic process in which a feedback is produced between its chronological dimension (perception and measuring of physical time) and the historical (knowledge of time in the history of humanity). It has as its fundamental objectives the offering of pedagogical strategies which will contribute to the development of this competence in children, forming the basis of their future education as well as revising the classic educative theories about the learning of time. In particular, in relation to historical time where the employment of hyper-media timelines and the most original technology of improved virtual reality and 3D systems can contribute to an approach being given to their introduction for comprehension at an earlier age. Concurrently, the correct integration of those novel tools and telematic and computational systems in education, especially from the humanistic and analytical viewpoint, will permit the adoption of critical attitudes in the school with regard to the fictitious and virtual reality produced. It will contribute, in this manner, to facilitating a better comprehension of the modern world and the presence and functions that these play in society, in a constructivist context of the development of knowledge, science and culture. © 2016, Ecozone, OAIMDD. All rights reserved.

Friedman J.S.,Metropolitan University of Puerto Rico
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

We have founded the Puerto Rico Photonics Institute (PRPI) in the Barceloneta, Puerto Rico campus of the Universidad Metropolitana. PRPI is established to provide opportunities in education, training and research and is unique in Puerto Rico. There are two initial focus areas of research and education: aerospace photonics and remote sensing. In particular, we will conduct studies and research and development in two particular fields: laser gyroscopes and similar technologies, and atmospheric remote sensing. PRPI has established local collaborations with the Arecibo Observatory and Honeywell Aerospace. Outside of Puerto Rico, PRPI collaborators include the University of Central Florida (CREOL), University of Arizona (OSC), University of Dayton (UD), Georgia Institute of Technology (GT), Scientific Solutions, Inc. (SSI), Atmospheric and Space Technology Research Associates (ASTRA), and the MIT Draper Laboratory. These organizations will help PRPI to: 1) establish its curriculum, provide research opportunities for PRPI students, 2) participate in faculty exchange programs, and 3) build its own research and development programs. PRPI will have educational and training programs for both Associate and Masters degrees, as well as a Certificate in Optics and Photonics for undergraduate science and engineering majors and professional engineers. PRPI is supported by UMET™s parent institution, the Ana G. Mendez University System (SUAGM), the Puerto Rico Science, Technology and Research Trust (PRST), and the Puerto Rico Industrial Development Company (PRIDCO). © 2014 SPIE, OSA, IEEE, ICO.

Primera-Pedrozo O.M.,Metropolitan University of Puerto Rico | Ates M.,Jackson State University | Arslan Z.,Jackson State University
Materials Letters | Year: 2013

Silica encapsulation of lead selenide quantum dots (PbSe QDs) in aqueous solution is reported. Thioglycolic acid (TGA) stabilized PbSe QDs were modified with 3-mercaptopropyl trimethoxysilane (MPS) through vigorous stirring in water for 18-24 h in alkaline solution (pH 10.4-10.6). Silica shell was developed by controlled deposition and precipitation of silicates from sodium silicate solution onto MPS modified QDs surfaces. TEM images showed multiple PbSe QDs encapsulated in silica shell. The size of PbSe-SiO2 core-shell nanocrystals was estimated to be 25-30 nm by TEM. Elemental compositions (Pb, Se and Si) were investigated by EDX analysis. The purified colloids of PbSe-SiO2 QDs were stable for months when kept at 4 °C. © 2013 Elsevier B.V. All rights reserved.

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