During years 2008-2009, a diagnostic regarding chemical reagents management (aspects related with; regulations, safety procedures, handle and storage conditions, etc) in teaching and research laboratories of the Universidad Nacional, was carried out. In order to collect such information different strategies/methodologies were used: 1) application of an interview and questionnaire to the laboratories’ personnel, 2)an inspection of the laboratories, 3) generation of chemical reagents database 4) work sessions with university management authorities and 5) interview with chemical products management personnel of public and private institutions .This study allowed to identify the actual conditions for the chemical reagents management at Universidad Nacional, for example; the different procedures for the segregation, storage, labeling and use of the chemicals, as well as the aspects related with; chemical database generation, material and safety equipment control, use of safety procedures, etc. Also, the study allowed to evaluate the existing management procedures executed by university authorities for handling them appropriately. As a conclusion, in order to conduct an adequate chemical reagents management at Universidad Nacional it is necessary to formulate and implement regulation (institutional procedures, protocols, etc) and the establishment of an university office in charge of all the chemical reagents management activities and procedures. Also is necessary to generate national regulations focused on university activities (chemical reagents management) as well as the existing for the industry chemical products control and regulation.

The type of knowledge and experiences that mathematics teachers need to develop as part of their initial training, has been a subject of controversy and discussion. This article aims to make a literature review of the most significant theoretical issues that have been made in this area, as well as the national trends, according to some authors. Inputs presented here, summarizes important findings that has contributed during the past four decades. It is expected that the results generate reflections among the educational community at Costa Rica on the topic and help in guiding the curriculum of mathematics teacher training of the country.

The purpose of this research was to gain knowledge about expectations, feelings, and perspectives of students with special needs in mathematics, in a high school context, to create a profile of these students. The focus of this research was placed on six students from eleventh grade that have this condition. The institution selected was a public academic high school, in the state of Heredia. The method used to collect and to analyze data was a case study. The main techniques included: class observation, a questionnaire, unstructured interviews to the teacher and to students, and clinical interviews for students with special needs. Among the relevant findings is it was evidenced an absence of modifications to the curriculum implemented by the teacher in mathematics classes, except for an extra lesson given to these students during written tests. Among the limitations of the focus students to learn mathematics, they used poor mathematics concepts and previous related knowledge. Another finding regards to the lack of communication among all the actors related to the process of implementing Curriculum modifications for students with special needs. Nevertheless, students with this condition help each other and in that way show their solidarity. Based on the findings, it is recommended that mathematics teachers must revisit concepts from previous contents studied, when participant students have concept knowledge limitations. Also, they ought to evaluate closely any advancement that students with special needs make.

This paper summarizes the opinions of students who have enrolled in the Precalculus course offered by the MATEM project. The aim is to systematize the views expressed by the students enrolled in MATEM, which are related to general aspects of the project, and also to know the professional areas these students select when entering to the university. The information for this study was collected through two questionnaires administered to the participating students during 2005-2009. The most relevant results are the following: the students listed benefits from MATEM such as the opportunity to practice for their Mathematics test (Ministry of Education exam), obtaining new knowledge and developing mathematical and reasoning skills. Most students would recommend others to participate in the project. Regarding the careers that students pursue, it was found a preference for higher studies in public universities at Costa Rica; these majors include mathematics courses in their curriculum (Engineering, Economics, Statistics, Medicine, among others).

This paper show the current state of a computer system that will allow the recognition and taxonomic classification of pollen grains of some of the most important tropical honey plants in Costa Rica using techniques of pre and post processing of digital images. The digital system uses filters on the images allowing it to detect and highlights its features and contour. Afterwards it is parametrized and finally a system of neuronal interconnections is used for the automatic recognition of pollen grains. The idea behind the implementation of a computer program is to move from a qualitative to a quantitative paradigm, using different mathematical tools and artificial intelligence in a way that can speed the process of recognition and classification of pollen grains. Using the PCA and the Sum at the outputs (CA) of 30 networks were able to obtain a success rate of 91,67 ± 3,13 which is highly promisisng for the purpose of the automatic classification system.

This article discusses the application of the model of Van Hiele geometric reasoning and the teaching of geometry. It reflects on the importance of studying geometry and what this means for modern society, analyzing also the conceptions and difficulties that exist in the form of teaching and learning geometry. Introduce the Van Hiele model explaining the evolution of geometric reasoning through five consecutive levels and the support given, by its five stages, to the organization of the curriculum and a comparison with the development theory of Piaget.

The present article has as purpose to present the results of an experience carried out with high school students with on the issue of the Pythagorean theorem and its reciprocal supported the use of GeoGebra and in the Van Hiele geometric reasoning model. For this it was designed and it implemented a methodological strategy, with twelve activities, to a group of ninth year of secondary education of Costa Rica, in the II trimester 2009, and compared the level of reasoning displayed by them with those who worked on this topic a traditional approach. The study was of qualitative type. Among the main findings highlighted that students who developed the activities supported by the GeoGebra felt more motivated to study Mathematics, especially Geometry, than those who did so under the traditional approach and the methodological strategy used in managed make many of the students who had low grades were motivated to "compete" and discuss mathematical ideas with students who had better grades than them, so that we can say that this strategy helped to strengthen their confidence in their interaction with others.

We present the current status of a research project with the main purpose to provide both students and teachers of Mathematics, to level nationally, a system capable of supporting multimedia theme study in secondary roles. The project comprises all steps required for the development of virtual tutor and corresponding validation by potential users. As one of the steps mentioned above, we applied a diagnostic questionnaire to three high school groups from both public and private institutions located in different social sectors of Costa Rica (rural, urban and urban fringe) and ten secondary school teachers to determine the cognitive needs of students in this subject and system requirements subsequently developed and is presented as part of this article.

Diminishing the polluting effect of wastes upon citizens and the environment represents an important aim to fulfill to guarantee a better life quality and a sustainable development. To address this problem a classification system of any chemical output and a score based in the quantity and danger was obtained by a control banding technique. By developing a spreadsheet based in this concept, the entries were specified for the chemical and toxic properties of any substance with a MSDS registry. From this work, it was obtained a classification based in the quantity, concentration, known toxicity and effects (i.e. LD50 and Risk Phases, known as R phrases) inside a fixed scale for each point. This tool can be applied to several situations where chemical wastes cannot be assessed once they are eliminated.

A hydrographic survey was carried out in the Jaltepeque estuary in the Pacific coast of El Salvador. From September 2005 to March 2006, 10 sampling stations were occupied to measure temperature, salinity, dissolved oxygen and turbidity. Surface temperatures between 27 and 30.6 °C were observed during the survey, with extreme temporal variations close to 3°C. Minimum temperatures occur in October and February. Surface salinity shows a clear seasonal cycle, with values greater than 30 o/oo during the dry months over virtually the whole body of water, while in the rainy season (September-October), salinity ranges from 2 o/oo to 22 o/oo. Maximum surface oxygen and turbidity were observed from October to December and minimum values in March. During the dry months (December- March), turbidity levels are low throughout the estuary. The vertical termohaline fields show a stratified estuary during the rainy season. This stratification breaks down during the dry season and the system behaves as well-mixed estuary. Dissolved oxygen did not show significant vertical stratification during the survey.

The present work aims to a preliminary study of the deproteinization capacity of proteolytic extracts from pineapple biowastes in different concentrations as potential green process to treat by-products of the shrimp fishery in order to obtain chitin and chitosan. The proteolytic extract isolated from pineapple biowastes was obtained from pineapple stems using a sulfuric acid buffer solution. The proteolytic extract from pineapple was characterized according to its protein content, total sugars and enzymatic activity against a commercial bromelin standard and a negative control. Results indicate that applying a crude pineapple proteolytic extract succeeded in to eliminate up to 97% of the proteins present in a shrimp biowaste sample, being more active than any of its dilutions, in a 24 hours study. Our results suggest that pineapple biowastes can be consider as a potential green biosource to promote shrimp deproteinization, providing a biotechnological activity to the traditional chemical process involving sodium hydroxide. This novel methodology will provide new applications for pineapple biowastes and reduce costs and contamination during chitin and chitosan production.

The chemical and technological accidents are unexpected events where non- controlled release of one or more chemical substances can affect the security and health of the community involved with negative impacts to the environment. This study presents the first atlas of chemical and technological threats of the greater industries in the Great Metropolitan Area of Costa Rica. In the residential areas of Alajuela and Heredia, the companies that use chloride gas, nitric and hydrochloric acid represented the greatest threat. In Cartago, the most important threat relied on the industries that use chloride gas. In San Jose, hospitals and health centers are under a high pressure due to the conjugation of two factors: high industry density and presence of the most important hospitals in the country. Likewise, the atlas also show the strategic position of many industries which are located on rich aquifers zones; indeed 87 % of the industries in San José are located above aquifers, 33 % in Alajuela, 83 % in Heredia, and 88 % in Cartago. The most affected rivers were found to be Ciruelas, Virilla, Turales, Bermúdez, Torres, Tíribi, Chiquito y Taras.

A simple and rapid method for the determination of ethanol in air was designed, using a chilled glass spiral for sampling and a flow injection system coupled to a column containing alcohol oxidase, immobilized on glass beads and a fluorescence detection system for analysis. We evaluated the excitation wavelength (310 nm) and the emission wavelength (410 nm), the flow of the mobile phase (1,05 mL min-1), the length of the reactor (1,00 m), the length (7,00 cm) and the diameter (3,0 mm) of glass column containing alcohol oxidase and the concentration of sodium hydroxide solution (0,15 M). The analytical method was linear from 1,00 µmol L-1 to 5,00 µmol L-1 ethanol. We obtained a correlation coefficient of 0,995, a repeatability of 0,8 %, a limit of detection and quantification of 0,350 µmol L-1 and 0,670 µmol L-1, respectively. The methodology was evaluated in field sampled and the ethanol concentrations in air ranged from 0,356 ± 0,001 mg/m3 and 1200 ±2 mg/m3. These concentrations did not exceed the maximum allowable limit of 1884 mg/m3, according to OSHA.

Foliar fertilization is an effective practice to correct nutritional deficiencies in plants that are under stress conditions or in soils with low nutrient availability, and consists in applying nutrient solutions directly on leaves. Nutrient absorption in the leaf occurs mainly through the epidermis, by diffusion, due to the nutrient concentration gradient established between the leaf surface and the epidermis interior. Once the nutrient has entered the cytoplasm of the epidermal cells, its movement happens in a relatively expedited fashion. The main barrier the nutrient has to pass is the cuticle, which is comprised of waxes. The physico-chemical characteristics of the nutrient, such as size and polarity, control the absorption rate. The present article provides a detailed description of the foliar absorption of nutrients and its influence on the development and use of foliar fertilizers.

The extension work of the School of Chemistry at the UNA, has been reflected from its beginnings to a large extent by the activities from the Program for Improving the Teaching of Chemistry (PMEQ). Efforts have been shared by many generations of teachers, academics and students with the passing of the years. Incipient work since 78 and in essence have continued to evolve and create spaces that seek to reverse the differences in educational access and quality. In the last ten years has been working with 4120 high school students (Project CAES), to train 270 teachers and about 6000 students have participated in Chemistry Olympiad. The rate of reports of students who choose chemistry for high school exams has increased. Efforts to promote the development and encouragement to scientific vocations have certainly paid off, talented students choose chemistry as a career in public universities, some of this by taking the undergraduate and graduate level, and some others in universities like MIT in the USA. We are sure that in a few years we are going to see them leading scientific processes in several fields of national production activities.

The opening in Costa Rica of a fair cognitive competition in the field of biological sciences responds to educational and social needs. This activity has increased year by year the interest of youth all over the country and of their teachers in the conceptual understanding of the biological field, through the organization of spaces for reflection, deepening and conceptual thinking during the development of classes, workshops, trainings and academic debates. The activity is supported by various government agencies, professional associations and private institutions. The objectives of this project are to enhance students in developing their abilities, cognitive skills and attitudes and to create opportunities for professional development in tutor teachers, promoting the implementation of procedural, conceptual and attitudinal aspects in their teaching. This paper seeks to highlight these purposes.

During years 2008-2009, a diagnostic regarding chemical reagents management (aspects related with; regulations, safety procedures, handle and storage conditions, etc) in teaching and research laboratories of the Universidad Nacional, was carried out. In order to collect such information different strategies/methodologies were used: 1) application of an interview and questionnaire to the laboratories’ personnel, 2)an inspection of the laboratories, 3) generation of chemical reagents database 4) work sessions with university management authorities and 5) interview with chemical products management personnel of public and private institutions .This study allowed to identify the actual conditions for the chemical reagents management at Universidad Nacional, for example; the different procedures for the segregation, storage, labeling and use of the chemicals, as well as the aspects related with; chemical database generation, material and safety equipment control, use of safety procedures, etc. Also, the study allowed to evaluate the existing management procedures executed by university authorities for handling them appropriately. As a conclusion, in order to conduct an adequate chemical reagents management at Universidad Nacional it is necessary to formulate and implement regulation (institutional procedures, protocols, etc) and the establishment of an university office in charge of all the chemical reagents management activities and procedures. Also is necessary to generate national regulations focused on university activities (chemical reagents management) as well as the existing for the industry chemical products control and regulation.

During years 2008-2009, a diagnostic regarding chemical reagents management (aspects related with; regulations, safety procedures, handle and storage conditions, etc) in teaching and research laboratories of the Universidad Nacional, was carried out. In order to collect such information different strategies/methodologies were used: 1) application of an interview and questionnaire to the laboratories’ personnel, 2)an inspection of the laboratories, 3) generation of chemical reagents database 4) work sessions with university management authorities and 5) interview with chemical products management personnel of public and private institutions .This study allowed to identify the actual conditions for the chemical reagents management at Universidad Nacional, for example; the different procedures for the segregation, storage, labeling and use of the chemicals, as well as the aspects related with; chemical database generation, material and safety equipment control, use of safety procedures, etc. Also, the study allowed to evaluate the existing management procedures executed by university authorities for handling them appropriately. As a conclusion, in order to conduct an adequate chemical reagents management at Universidad Nacional it is necessary to formulate and implement regulation (institutional procedures, protocols, etc) and the establishment of an university office in charge of all the chemical reagents management activities and procedures. Also is necessary to generate national regulations focused on university activities (chemical reagents management) as well as the existing for the industry chemical products control and regulation.

The extension work of the School of Chemistry at the UNA, has been reflected from its beginnings to a large extent by the activities from the Program for Improving the Teaching of Chemistry (PMEQ). Efforts have been shared by many generations of teachers, academics and students with the passing of the years. Incipient work since 78 and in essence have continued to evolve and create spaces that seek to reverse the differences in educational access and quality. In the last ten years has been working with 4120 high school students (Project CAES), to train 270 teachers and about 6000 students have participated in Chemistry Olympiad. The rate of reports of students who choose chemistry for high school exams has increased. Efforts to promote the development and encouragement to scientific vocations have certainly paid off, talented students choose chemistry as a career in public universities, some of this by taking the undergraduate and graduate level, and some others in universities like MIT in the USA. We are sure that in a few years we are going to see them leading scientific processes in several fields of national production activities.

A small producer has built in his property a low cost non- conventional wastewater treatment, characterized by maintenance and operation easiness, and aesthetical suitability; complemented with the implementation of environmentally friendly practices. The system involves reduction in water consumption, utilization of biodegradable products, treatment of wastewater and reuse, use of alternative energies, gravity watering, among others. Sewage and grey waters of the house are collected separately; the first one goes to a biodigester, followed by two small ponds with floating vegetation. Grey waters are treated in a series of three small ponds, with aquatic plants. The effluents of both subsystems are getting together and conducted to other two ponds; the final effluent is discharged into the Catalina River, where it was determined the Water Quality Index of the NSF and the BMWP Index, modified to Costa Rica. The system was evaluated for nine months; it was very successful in reduction of BOD, phosphates and nitrates, however, it is not as effective in the removal of fecal coliformes. In general terms, the effluent does not affect the water quality of the Catalina River.

The purpose of this research work was in the first instance, to conduct a study of the content of phyllantosides and lignans in samples from different parts of the tree known as “Chilillo” (Phyllanthus acuminatus Vahl), collected at different sites of the country. The first objective of the study was focused on the characterization of the samples using high efficiency liquid chromatography (HPLC). The results obtained by this technique showed variation not only in the number of peaks in each chromatogram, but also in the peak intensity, also significant variations in the composition of the samples were found among the different collecting sites. The second objective of this work, was to develop a simple, fast and inexpensive colorimetric method to quantify the content of phyllantosides and lignans in different samples of Chilillo that was comparable to the HPLC data. The results obtained with the new method were correlated with the results obtained by HPLC, the coefficient of determination obtained in this correlation was excellent and statistically significant (R2 = 0,99; p < 0,05). Finally, the last objective of the study was to evaluate the antioxidant activity in all the samples of Chilillo and its correlation with its total polyphenolic content, using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) for antioxidant activity determinations and Folin-Ciocalteu for total polyphenolic content. Traditionally there is a good correlation between total polyphenol content and antioxidant activity, but in this study the correlation between the two methods was relatively low (R2 = 0.4334). These results clearly show that Chilillo tree can not be consider as an important source of polyphenols or natural antioxidants, especially when compared with other plant samples rich in phenolic compounds such as blackberry (Rubus sp) or rambutan (Nephelium lappaceum).

In Costa Rica wastewaters are usually deposited in septic tanks where settling processes occur with effluent infiltration into the ground subsurface. This practice presents a major risk to human health and a negative impact on the environment due to possible groundwater contamination. The following case study presents the application of an artificial subsurface horizontal wetland as a low-cost alternative using a rooted emergent macrophyte system for the treatment of sewage wastewater generated within a cosmetic and pharmaceutical manufacturer. The Cyperus papyrus, a common species easily adaptable to the country`s climatic conditions, was used in the removal of organic load from sewage discharge with an efficiency between 61% and 90%. Final effluent water quality after treatment was in compliance with current national legislation. The results obtained demonstrate the effectiveness of such biological system as an innovative wastewater treatment alternative in countries with tropical climate

Some simple comparisons were made between recursion and iteration algorithms to determine the efficiency of a particular problem. To perform the tests three examples of algorithms types were used, to which we will apply algorithms analysis criteria.

In Costa Rica the use of toxic pesticides has increased. This is mainly due to the development of resistant pests, and the need for certain agricultural export products to maintain its position in the international marketplace. Humans when in contact with pesticides can experience adverse health effects, ranging from acute to chronic and that manifest in different degrees. To generate indicators of the hazards arising in the human health posed by the use of these substances in some crops, the amount of pesticides applied and their toxicity was used. Data of pesticide use were collected directly from producers, through a questionnaire. The active ingredients identified were characterized in accordance with their toxicity and classified according to the manifestation of the effects. The indicators used were the amount of pesticides applied (kg ai / ha / year) for the most considered toxic class: 1-effects for acute toxicity on high-grade and, 2- the pesticides with three or more positive chronic effects. It is recommended to monitor the use of methyl bromide, metam sodium, terbufos, ethoprophos, endosulfan, MCPA and carbofuran for high to extreme acute toxicity, and the one of mancozeb, paraquat, diazinon, 2,4-D and carbofuran for chronic effects.