bluuebunny/crossref_metadata_2025 huggingface dataset:
Fracturing Evaluation for Fractured-Caved Carbonate Reservoirs through Pressure Transient Analysis and Rate Transient Analysis
Authors: Li Yong , Wang Qi , Li Baozhu , Deng Xingliang , She Zhicheng , Liu Zhiliang
Published: August 2016

Naturally fractured-caved carbonate reservoirs in China have some distinctive characteristics: deeply buried, multi-scale fractures, vugs and caves developed, strong heterogeneity, poor reservoir connectivity and no oil in matrix. Hydraulic fracturing is commonly used in order to connect offset fracture-cave system with wellbore and improve well performance for this kind of reservoirs, while how to properly evaluate hydraulic fracturing efficiency is still a major challenge. This paper presents an integrated evaluation method to solve this problem.

The method mainly involves pressure transient analysis and rate transient analysis. Firstly, typical diagnostic curves of different fracture-cave patterns with and without hydraulic fracturing respectively are established through design analysis of numerical conceptual models. Then the curves are used for actual well stimulation and evaluation. Finally, reservoir properties of fracturing wells such as OOIP, hydraulic fracture properties, reservoir permeability, etc. are evaluated based on the integrated pressure transient analysis and rate transient analysis method.

This new method has been applied to Tazhong No.I fractured-caved carbonate gas condensate reservoir in China. The reservoir's mid-depth is around 6000m and is currently under primary depletion development with an average annual production declining rate higher than 25%. Based on the understanding of seismic interpretation and geological study, 3 major reservoir patterns and 7 sub-patterns are classified. Then corresponding conceptual numerical models of these patterns with and without hydraulic fracturing are established, and typical diagnostic curves of pressure transient analysis and rate transient analysis for identification of these patterns are generated. And then, the results are applied to the actual well fracturing evaluation in Tazhong NO. I carbonate gas condensate reservoir.

This systematic technique has been successfully applied to Tazhong No. I fractured-caved carbonate reservoir in Tarim Basin of China, which properly and correctly evaluates the properties of the hydraulic fracturing wells. It also provides a reliable method for decision making of hydraulic fracturing, which is helpful for effective and economic development of the reservoir.
Investigating and Optimizing the Use of High-Hardness Produced Water as Fracturing Fluid: A Simulation Approach
Authors: Bao Chen , Han Jiahang , Sun Hong , Sookprasong P. A.
Published: August 2016

The ongoing low oil price environment has profound impact on all the operators and service providers. Efficiency improvements and cost reductions are two key strategies to capture the opportunities in current situation. It is now imperative for engineers to improve engineering practices to gain efficiency and drive down the cost. However, in well stimulation practices, it is vital to all stakeholders to obtain fracturing fluids with desirable fluid viscosity, and thermal and chemical properties with cost as low as reasonably possible.

Preparing fracturing fluids with high-hardness produced water is one option to drive down cost. Such a practice eliminates the need to transport fresh water and dispose wastewater. However, it may not be possible because of the reaction tendencies between cations and functioning polymers within fracturing fluids. Although combinations of chemicals including polymers, chemical additives, stabilizers, and buffers can be added to prevent such reactions, the dosages of each component are often hard to quantify and often dependent on the experience of field engineers. A fast prognosis tool has been developed to facilitate such a decision-making process by identifying the lowest possible dosages of chemicals dependent on produced water hardness. With such a prognosis tool, it is now possible to make more educated and cost-effective plans to optimize the engineering practice.

In this work, the underlying physics of hard water damage to fracturing fluids is discussed, followed by a demonstration of the simulations that reproduced the lab rheology experiment results. The viscosity profiles of a number of rheology experiments were first matched as model calibrations. The effects of different stabilizers were then discussed by parametric comparison of different cases. With the predictive model successfully capturing the reaction system, a dynamic algorithm was built to compute the lowest cost possible solution of functioning fracturing fluids in a given system. Due to the non-linear nature of the chemical reaction system, a searching algorithm was implemented to minimize the cost of fracturing fluids as functions of local produced water hardness, cost of each chemical component and operational expenses.

This work demonstrates that good engineering practices are achieved through carefully understanding and modeling a working system, and through dynamic planning of the overall workflow with cost optimization as a target. All in the form of a prognosis tool that could be easily implemented in the current fracturing fluid preparation work flow.
Magnetic Recovery-Injecting Newly Designed Magnetic Fracturing Fluid with Applied Magnetic Field for EOR
Authors: Shekhawat Dushyant Singh , Aggarwal Avi , Agarwal Soham , Imtiaz MD
Published: August 2016

Ferrofluids are Fe3O4 based Magnetic Nano Particles (MNPs) and can be coated with a layer to form a super-hydrophobic material which selectively adsorbs oil. These colloidal ferromagnetic nano-particles show remarkable magnetic susceptibility. The ability of ferrorfluids was at display in the Gulf of Mexico and other oil spill clean-up. Excellent on-surface results suggest us to exploit its potential under sub-surface conditions too. The paper puts forward the potential on MNPs in EOR/IOR, proper production scenarios and techniques to inject this magnetically-controlled oil-adsorbing fluid through pad during hydraulic-fracturing operations.

Sodium oleate coated magnetite (Fe3O4) is found to be the best suited MNP constituent for pad fluid. Fe3O4 particles modified with sodium oleate have successfully been able to generate super-hydrophobic surfaces. Their average size ranges from ~5nm to 10nm, thus are capable of getting suspended in pad fluid during injection and passing through the oil bearing zone without plugging the pores during fracturing operation. MNP's motion can be forced and controlled by applying magnetic field which makes MNPs a great asset for improvisation of fracturing techniquesn (Experimentally tested over 100 different oil and heavy crude oil at FERMILAB, Batavia Illinois).

Injecting highly viscous Frackfluid ‘pad’ is amongst the primary part of fracturing job as it is used to initiate/propagate the fracture. Continuous loss of pad to formation will cause fracture propagation and at the final stage pad will be completely lost to the formation. Oleate coated MNP injected along with pad will selectively adsorb oil in the region where pad interacts with oil in formation. Initially applying outward magnetic field will cause solid MNPs to reach farther in formations, leaving behind the injected fluid in nearby formation, to sweep maximum reservoir volume. Second step is to apply an inward field towards the bore hole, which will force the MNPs to trace back into the wellbore along with adsorbed hydrocarbon on their surface. Magnetic field can easily drive these nanoparticles through tight/low permeable reserves and during heavy crude recovery. Their selective adsorption and hydrophobic nature can be of great significance in production through water bearing zones. Prepared MNP is both hydrophobic and lipophilic. Therefore Fe3O4 with sodium oleate could be soundly dispersed in the oil medium present in formations and recovered by applying magnetic field directed toward producing well.

This technique shows a new path for the industry in advanced fracturing operations involving fracturing through deep, heavy oil reserves, HPHT and highly water saturated reserves. Validity of the proposed process has been elucidated in the paper considering various technical and operational variables.
Source Mechanism Studies of Acoustic Emission in Large-Scale Hydraulic Fracturing Experiment
Authors: Tiancheng Liang , Haifeng Fu , Yongjun Lu , Yunzhi Liu , Jingjing Dou , Nailing Xiu , Guorong Tian
Published: August 2016

Hydraulic fracturing plays a significant role in unconventional oil and gas reservoirs. The hydraulic fracture initiation and propagation mechanism is fundamental important, but is understood unclearly. The large-scale hydraulic fracturing experiment, with the sample size of 30in*30in*36in, can simulate reservoir stimulation under the in-situ stress with the acoustic emission (AE) monitoring. AE is used to monitor fracture initiation and propagation in real-time and analyze the source mechanism of rocks.

The shear slippage can effectively enhance reservoir permeability, which makes the source of AE events important. In order to characterize the source mechanism, two methods are used in this paper: (1) the moment tensor inversion analysis, using P-wave first-motion polarities and amplitudes to determine crack type classifications from a unified decomposition of eigenvalues; (2) the single wave characteristic parameter analysis, using RA value (=the rise time/the maximum amplitude in mV) and average frequency (= AE ring down-count/the duration time) respectively as horizontal axis and vertical axis to plot a scatter diagram.

According to large-scale experiments with sandstone, coal and shale, results show that: (1) The conclusions obtained by the two methods are similar. Using the single wave characteristic parameter analysis to evaluate fracture mechanism in fracturing simulation experiment, the fractures are classified into two major groups: tensile fractures and shear fractures. (2) Tight sandstone only produces tensile fractures. The coal, shale and naturally fractured sandstone blocks have more complex mechanism with tensile and shear fractures, due to the existence of favorable natural fractures under specific in-situ stress and the injection pressure. (3) Spatial and temporal distribution of hypocenters is observed. A bi-wing planar fracture is formed in tight sandstone, but non- planar fracture networks exist in coal and shale blocks.

This work can help engineers establish a proper model for the estimation of effective stimulated reservoir volume (ESRV) using the microseismic data in hydraulic fracturing.
Eco-Friendly Hydraulic Fracturing Fluid: Field Deployment and Performance Evaluation in Saudi Arabia's Tight Gas Reservoirs
Authors: AlKhowaildi Mustafa A. , AlGhazal Mohammed A. , Al-Driweesh Saad , Abbad Emad , Abdrabalnabi Hussain
Published: August 2016

With the increase in demand for energy, natural gas from tight reservoirs is being targeted abundantly around the globe by different operators using hydraulic fracture technology. Reducing the environmental footprint associated with hydraulic fracturing is a priority in optimizing this technology. An environment friendly, polymer-free fracturing fluid has shown remarkably consistent results, following multiple deployments in Saudi Arabian tight gas formations.

Alongside laboratory tests, field studies such as fracture geometry and conductivity, ecological impact and well productivity were investigated over several wells targeting the same formation. The main objective was to test the field performance consistency of the fluid. Also, integrated post treatment results were collected as case histories for comparison to offset wells.

Flowback data indicated significant reduction in fracture cleanup time with 95% retrieved fluids compared to 40-60% in polymer-based fluid. Therefore, improvement in early production response was noticed due to higher retained permeability and proppant pack was left damage-free due to minimal residue left inside the formation. The post treatment reports indicated improved fracture conductivity and geometry containment in the pay zone compared to offset wells that used conventional polymer-based fluids. Additionally, because of its enhanced viscoelastic nature, the fluid system exhibited excellent proppant transport capacity at low viscosity without compromising fracture half length.

The environmentally friendly surfactant-based fracturing fluid demonstrated superior performance in tight sand formations of Saudi Arabia, especially while stimulating zones in close proximity to water zones where contamination must be prevented. This paper will also discuss the potential of further development to this fluid such as improving its overall efficiency that could mark future technological advances in the petroleum industry.
The Effect of Rock Properties on Fracture Conductivity in the Marcellus Shale
Authors: Perez Pena P.. , Zhu D.. , Hill A. D.
Published: August 2016

The success of fracture stimulations depends on the ability to fracture the rock and to maintain fracture conductivity. Therefore, in order to have a successful treatment, the effect of rock and proppant characteristics should be understood. This paper investigates the relationship between fracture conductivity and rock properties for two different locations in the Marcellus shale.

In this work, a series of experiments were performed in order to better understand the mechanical behavior of the Marcellus Shale. Multiple cores from Allenwood and Elimsport locations in Pennsylvania were collected to ensure repeatability in the results. The core samples were cut parallel and perpendicular to the bedding planes in order to analyze the effect of anisotropy in fracture conductivity. Additionally, compressive triaxial tests were performed to obtain the rock mechanical properties such as Young's Modulus, Poisson's Ratio and Ultimate Compressive Strength, and X-ray Diffraction analysis was used to obtain mineralogy composition.

The laboratory results were carefully compared with previous fracture conductivity data and surface roughness data from the same Marcellus shale locations where proppant concentration was kept constant to reduce the variables affecting the fracture conductivity behavior. The findings showed that the anisotropy effect is present for this formation and reflected in the fracture conductivity values, where samples parallel to the bedding plane seem to have higher Young's Modulus. It was confirmed that at proppant monolayer concentration the main mechanism for conductivity loss is proppant embedment, where due to the high localized stress, the rock-proppant interaction goes directly to permanent deformation of the rock. It was also observed that a higher Young's Modulus helps to maintain the fracture width which translates in lower rate of conductivity loss with increasing closure stress, therefore, rock mechanical properties have impact on fracture conductivity. The phenomenon observed is less pronounced if a multilayer proppant concentration is used, where the proppant pack characteristics become an important parameter in fracture conductivity.

In this paper, we present an analysis of the effect of rock properties in the fracture conductivity behavior based on a series of experimental results from the Marcellus Shale, where the role of permanent deformation was taken into consideration as a parameter causing fracture conductivity lost. This is the first time the effect of rock characteristics in fracture conductivity is analyzed based on experimental work for the Marcellus shale.
Editorial: Disciplinas de la ingeniería Colombiana: ¿dignas de exportación?
Authors: Gaviria-Hincapié Jorge Mario
Published: August 2016

Aún encuentro profesionales que no hacen respetar la profesión; necesitamos formar un ingeniero generalista que pueda aplicar creativamente soluciones a problemas colombianos, conociendo nuestro entorno y estimulando la conservación y mejora del mismo.
Estudio sobre consumo de drogas y acoso escolar entre cursantes de la enseñanza primaria en Costa Rica
Authors: Fonseca Chaves Sandra , Ortega Bonilla María Auxiliadora , Cubillo Otárola Freddy , Bejarano Orozco Julio
Published: August 2016

En este estudio se analiza la problemática del consumo de alcohol, tabaco y otras drogas, así como aspectos relacionados con el uso de tecnologías de la información y comunicación (TIC), intimidación o bullying en población escolarizada del segundo ciclo de educación primaria (4º, 5º y 6º grado) de cuatro escuelas urbanas y cuatro de atención prioritaria de las provincias de Alajuela, Cartago, Heredia y San José. Para tal propósito, se realizó una encuesta entre los meses de junio a noviembre del 2013, en una muestra de 537 estudiantes.  Los resultados evidencian un inicio temprano en el consumo de alcohol, así como una utilización importante de las TIC y la existencia de situaciones conocidas como cyberbullying, y problemas relacionados con el bullying, lo que evidencia la necesidad de continuar realizando esfuerzos en el nivel interinstitucional en favor de prevenir determinadas conductas de riesgo presentes en la infancia.
INTEGRALIDADE E ENSINO NA SAÚDE: REFLEXÃO TEÓRICO-LEGAL E RELATO DE EXPERIÊNCIA
Authors: Rios Leonardo Essado
Published: August 2016

A integralidade é um dos princípios orientadores para uma formação profissional em saúde mais integrada ao Sistema Único de Saúde (SUS). Neste trabalho, o objetivo foi relatar a experiência do autor após a realização de um seminário sobre Integralidade e Ensino na Saúde, desenvolvido durante um curso de mestrado em Ensino na Saúde. A análise descritiva é problematizada com base na seguinte legislação concernente: Constituição Federal de 1988, Lei de Diretrizes e Bases (Lei 9394/96), Diretrizes Curriculares Nacionais para os cursos de graduação na saúde e Programa de Reorientação da Formação Profissional em Saúde (Pró-Saúde). Conclui-se que buscar a integralidade no ensino na saúde é dever do educador e direito do educando. Uma formação profissional em saúde que promova cada vez mais a integralidade no Ensino na Saúde é recomendada, a fim de que cada vez mais os discentes estejam aptos a um adequado enfrentamento da realidade do SUS.
AVALIAÇÃO DOS NÍVEIS DE COTININA URINÁRIA EM FUMICULTORES DA REGIÃO NORTE DO RIO GRANDE DO SUL
Authors: Ehrhardt Alexandre , Berté Vanessa Daniela
Published: August 2016

O tabaco possui mais de 4.000 substâncias conhecidas, dentre as quais a nicotina é a que apresenta maior concentração na planta. Níveis elevados de nicotina no organismo podem levar a intoxicações e ao desenvolvimento da doença do tabaco verde. No organismo o processo de biotransformação da nicotina gera cotinina, considerada o biomarcador para a exposição ao tabaco. O objetivo deste trabalho foi avaliar os níveis de cotinina urinária em fumicultores da região norte do Rio Grande do Sul. Através de um estudo transversal, observacional e analítico, foram mensurados os níveis de cotinina urinária através de dosagens laboratoriais. Observou-se variação dos valores de 20,5 ng/mL a 515 ng/mL (106,96 ± 32,38), apresentando diferença significativa quando comparados aos valores de referência para não fumantes. Estes resultados indicam que os fumicultores podem estar propensos a intoxicações e podem evoluir para a doença do tabaco verde, que está diretamente relacionada à falta de uso de equipamentos de proteção e ao tempo de exposição às folhas verdes do tabaco.
CORRELAÇÃO ENTRE FATORES DE RISCO À SAÚDE DE ESTUDANTES DO ENSINO MÉDIO
Authors: Cação Junior Izael Rodrigues , Gasparotto Guilherme Da Silva
Published: August 2016

Descrever a ocorrência de fatores de risco bem como verificar como eles se relacionam são ações importantes para propor medidas de intervenção de combate ou controle desses possíveis problemas entre os adolescentes. O objetivo deste estudo foi descrever a prevalência de excesso de peso corporal, circunferência de cintura elevada, prática insuficiente de atividade física, risco alimentar e verificar a correlação desses fatores com as medidas de pressão arterial entre os alunos de ensino médio. Foram mensurados valores de massa corporal e estatura para o cálculo do IMC e a circunferência da cintura. Já a prática de atividade física foi obtida por meio do Intenational Physical Activity Questionnaire, com o qual se verificou a prática semanal de atividade física moderado-vigorosa (AFMV) e de atividade física vigorosa (AFV). Por fim, o risco alimentar foi identificado pelo Questionário Simplificado de Frequência Alimentar e a pressão arterial foi mensurada pelo método auscultatório com utilização de esfigmomanômetro analógico e estetoscópio. Dos 80 alunos matriculados nos cursos técnicos em Informática e Administração integrados ao ensino médio, foram avaliados 73, sendo que, desse total, 58,9% encontraram-se insuficientemente ativos, 21,9% com excesso de peso corporal, 13,7% com a circunferência da cintura acima do recomendado para a idade e 49,3% demonstraram comportamento alimentar de risco para doenças cardiovasculares. Foi detectada relação entre as variáveis minutos em AFV e pressão arterial diastólica (PAD) (r = - 0,24) bem como o IMC relacionado também com a PAD (r = 0,26). Foi possível perceber que mais da metade dos estudantes são insuficientemente ativos e que quase a metade deles se alimenta de forma inadequada. A análise de correlação mostrou, ainda, que, apesar de uma relação fraca, quanto mais AFV os alunos praticam menor a PAD e que os valores da PAD se elevam de acordo com o aumento do IMC.
Personality
Authors: Leicester Jonathan
Published: August 2016

The chapter opens by questioning the role of personality traits in causing
behaviour, and decides to work with the common assumption that they have an
important role. There is an account of the search for the real units or traits of
personality. Some of the traits and dispositions, selected for their particularly direct
effect on belief, for example, strong need for closure, are briefly described. There is a
comment on the way long-standing occupational roles can sometimes modify
personality.
Építőipari kockázatok vizsgálata
Authors: Cserpes Imre , Szabó József
Published: August 2016

A cikk egy hosszabb, a kockázatkezelés elméletét és általános módszertanát, valamint az építési projektek körülményei között való gyakorlati munka között feltételezett szakadék áthidalását célzó tanulmány egyik már elkészült részletén alapszik. A hangsúlyt az építési projektek kockázatok tipikus adatforrásaira, a projekt tervezésének módszereire helyeztük. Az építőipari kockázatok természetével és a kockázatkezelési módszerekről külön tanulmány készült.
Közbeszerzés lebonyolítása a hatályos jogszabályok tükrében
Authors: Diószeginé Zentay Éva
Published: August 2016

A Közbeszerzésekről szóló új törvény célja, hogy biztosítsa a közpénzek hatékonyabb felhasználását. Az új szabályozás eredményeképpen jelentősen meggyorsulnak a közbeszerzési eljárások, növekszik az átláthatóság és a verseny. Továbbra sem lesz egységes az uniós értékhatár alatti eljárások rendje, mivel a törvény a becsült érték alapján differenciálja a szabályokat. Fontos változás az értékelés kapcsán, hogy a kizárólag ár alapú rangsorolás helyett az ár-érték módszer alkalmazása kerül előtérbe.
Model calculations on the use of mobile and stationary units for wood pellet production
Authors: Szendrei János , Grasselli Gábor , Kocsi Balázs , Budai István , Szűcs Edit
Published: August 2016

This paper presents the model calculations made for supporting the decision making of different technology alternatives. Base cases were A) use of a mobile pelletizer and B) using pellet factories at fixed locations for the production of a new product, sheep wool pellets. Calculations were made for three alternatives for each base case. The results of the model were used to examine the energy, time and cost criteria of the alternatives. Based on the given preliminaries, results of the model calculations supported the recommendation to choose case B) for further technology management and supply chain management decisions.
Link between Corporate Philanthropy and Corporate Financial Performance: Evidence from Pakistani Textile Sector
Authors: Zulfiquar Sehar
Published: August 2016

Literature highlights the immense potential of Corporate Philanthropy (CP) for generating social and economic benefits. The debate on economic benefits align corporate philanthropy with the business bottom line arguing that it can be a significant determinant of corporate financial performance. This research is intended to extent this debate by providing sector specific perspective through analyzing the sample of Pakistani public listed textile companies. Results of the study show that corporate philanthropy has a significantly positive relationship with Return on Assets (ROA) but with Return on Equity (ROE) the relationship is found to be insignificant. The previous year’s financial performance moderates the relationship between CP and ROA but the interaction effect for ROE is insignificant.
The implementation of e-learning with team builder at vocational high schools
Authors: Patwary Mahmud Al Haq , Surjono Herman Dwi
Published: August 2016

This research is aimed at: (1) producing an appropriate e-learning for English language studies in vocational high school, (2) evaluating the suitability of the developed e-learning in terms of appropriateness, accuracy and clarity, screen presentation and design, and appropriateness of the team builder module aspect, and (3) evaluating the effectiveness of the e-learning in practical application. This research and development (RD) study used Alessi and Trollip’s model rearranged following ADDIE model, where the development of instruction followed Dick and Carey’s model and the need assessment procedures were adapted from Lee Owens. Overall appropriateness and quality of the e-learning from alpha testing is ‘very appropriate’ and from beta testing is ‘excellent’. Alpha testing reveals that, the Team Builder Module is ‘very appropriate’ and beta testing reveals that, its overall quality is ‘excellent’. The e-learning is highly effective. The average score of the students raises 3.82 points (or 42.44%) in the post-test from pre-test score. The minimum score of the post-test (i.e. 8) is more than the maximum score of the pre-test (i.e. 7), so it is concluded that the use of e-learning does not deteriorate the performance of the students, but improves their performance.
Strengthening vocational character for polytechnic education which has non-production-based curriculum
Authors: Handayani Peni , Brodjonegoro Satryo Soemantri
Published: August 2016

The vocational character of polytechnic education has declined in the last ten years, especially for polytechnic which has non-production-based curriculum. This research aims to reveal factors which have contribution in the devocationalization of polytechnic education, and to find out the alternative solution to revocationalize by considering the current condition and the future demand. This study applied qualitative approach supported by quantitative data that involved three polytechnics in Bandung and Malang, three industries in Bandung, one industry in Yogyakarta, and an expert as representative from the Department of Industrial and Cooperation Yogyakarta. Interpretational inductive analysis was used to analyze qualitative data. This study revealed: (1) environmental factors are very influential factor in shaping the character of polytechnic education and recognition; (2) the greatest gaining vocational character acquired through apprenticeship in industry or workplace; and (3) gaining vocational character needs to be managed by maintain and strengthen cooperation between polytechnic and industries, and competent institution which can develop education system.
Front Matters
Authors: - (Cover, Foreword, Table of Contents)
Published: August 2016

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Back Matters
Authors: - (Indexes, Biography, Author Guidelines)
Published: August 2016

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A formative assessment model of critical thinking in mathematics learning in junior high school
Authors: Rosnawati R , Kartowagiran Badrun , Jailani Jailani
Published: August 2016

This study aims to obtain a valid and reliable formative evaluation model of critical thinking. The method used in this research was the research and development by integrating Borg Gall's model and  Plomp's development model. The ten steps Borg Gall’s model were modified into five stages as the stages in the Plomp's model. The subjects in this study were 1,446 students of junior high schools in DIY, 14 mathematics teacher, and six experts. The content validity employed was expert judgment, the empirical validity and reliability used were loading factor, item analysis used PCM 1PL, and the relationship between disposition and critical thinking skill used was structural equation modeling (SEM). The developed formative evaluation model is the procedural model. There are five aspects of critical thinking skill: mathematic reasoning, interpretation, analysis, evaluation, and inference, which entirely composed of 42 items. The validity of the critical thinking skill instruments achieves a significance degree as indicated by the lowest and the highest loading factors of 0.38 and 0.74 subsequently, the reliability of every aspect in a good category. The average level of difficulty is 0.00 with the standard deviation of 0.45 which is in a good category. The peer assessment questionnaire of critical thinking disposition consists of seven aspects: truth-seeking, open-minded, analysis, systematic, self-confidence, inquisitiveness, and maturity with 23 items. The critical thinking disposition validity achieves the significance degree as indicated by the lowest and the high factor loading of 0.66 and 0.76 subsequently, and the reliability of every aspect in a good category. Based on the analysis of the structural equation model, the model fits the data.
Evaluation of the bridging course offered at a university to foreign students: Batches of 2012 and 2013
Authors: Perez Beatriz Eugenia Orantes , Mardapi Djemari
Published: August 2016

This evaluation was a case study of the bridging language program offered at YSU to KNB students, it evaluated the generations 2012/2013. The focus of this evaluation was to evaluate the strengths and weaknesses of the bridging program. This was a summative evaluation used the CIPP method. It was a pragmatic parallel mix-method design research. The analysis technique was descriptive for the qualitative data; and it was descriptive statistical for the quantitative data; Triangulation was used. 15 students, 6 teachers, 10 tutors, 3 administrators were involved. In each component of the evaluation strengths and weaknesses were found. The main strengths were: Clear cultural objectives, experience teachers, tutorials helped students a lot. The main weaknesses were: There is not clear criteria of the level to be reach, tutors lack training and time to prepare, material and assessment needs to be improve, students don’t reach an upper intermediate level of the language.
The effectiveness of web-based interactive blended learning model in electrical engineering courses
Authors: Effendi Hansi , Soenarto Soenarto , Sofyan Herminarto
Published: August 2016

The study was to test the effectiveness of the Web-Based Interactive Blended Learning Model (BLIBW) for subjects in the Department of Electrical Engineering, Padang State University. The design that the researcher employed was a quasi-experimental design with one group pretest-posttest, which was conducted on a group of students consisting of 30 people and the test was conducted for two times. The effectiveness of BLIBW Model was tested by comparing the average pretest scores and the average posttest scores both in the first trial and the second trial. The average prestest and posttest scores in the first trial were 14.13 and 33.80. The increase in the average score was significant at alpha 0.05. Then, the average pretest and posttest scores in the second trial were 18.67 and 47.03. The result was also significant at alpha 0.05. The effectiveness of BLIBW Model in the second trial was higher than in the first test. Those result were not entirely satisfactory and it might be caused several weaknesses in both tests such as: the number of sessions were limited, there was only one subject, and the number of students who were subjected too limited. However, the researcher would like to conclude that the BLIBW Model might be implemented as a replacement alternative for the face-to-face instruction.
Método de cría en laboratorio del gusano blanco de la papa Premnotrypes vorax (Coleoptera: Curculionidae)
Authors: Pérez Ricardo , Garza Jennifer , Argüelles-Cárdenas Jorge
Published: August 2016

El gusano blanco de la papa Premnotrypes vorax es considerado uno de los insectos plaga más limitantes del cultivo de la papa en Colombia. En este trabajo se describe un método para la cría de P. vorax en condiciones de laboratorio, con el que se puede obtener individuos de todos los estados de desarrollo para su uso con propósitos experimentales. Adicionalmente, se determinó la longevidad y fecundidad de los adultos para establecer el potencial de crecimiento de la cría en las condiciones evaluadas. Los adultos se mantuvieron en recipientes plásticos provistos de una capa de suelo, follaje de papa para la alimentación y pajillas para la oviposición. Las pajillas con posturas se desinfectaron y luego se incubaron en cajas de Petri en condiciones de temperatura y humedad controladas. Las condiciones más adecuadas para el mantenimiento de los individuos durante el período larva-adulto se determinaron evaluando dos tipos de alimento para las larvas, tres sustratos para pupar y tres densidades de larvas por tubérculo. Las mejores condiciones se obtuvieron con tubérculos de la variedad parda pastusa (> 80 g), sobre un sustrato de suelo esterilizado y turba en proporción 3:1 y a una densidad no mayor a diez larvas por tubérculo. Con este método de cría se podrían esperar de dos a tres generaciones del insecto por año con una tasa de incremento cercana al 17% por generación. Este método de cría se constituye en una herramienta para facilitar la realización de estudios bioecológicos del insecto y evaluar métodos para su control.
Frecuencias alélicas para variantes SNP en el gen Nramp1 en bovinos infectados con Brucella abortus o clasificados por resistencia al patógeno
Authors: Cerquera Fernando , Martínez Rodrigo , Toro Rubén , Tobón Jaime , Gallego Jaime , Rueda Esperanza
Published: August 2016

La resistencia natural a la brucelosis en bovinos ha sido asociada a factores genéticos, principalmente a algunos polimorfismos de nucleótido simple ubicados dentro del gen Nramp1. La presente investigación evalúa el efecto de variantes tipo polimorfismos de nucleótido simple presentes en regiones codificantes y en la región 3’UTR del gen Nramp1, en la clasificación de los animales como resistentes o susceptibles; además se determinan los genotipos predominantes en animales naturalmente infectados y comprobados como positivos por la presencia de anticuerpos anti Brucella abortus. Se establecieron las frecuencias genotípicas y alélicas para cinco polimorfismos de nucleótido simple identificados dentro del gen Nramp1 en animales de las razas blanco orejinegro (Bos taurus taurus) y cebú (Bos taurus indicus) y en muestras serológicamente positivas provenientes de animales cruzados (Bos taurus x Bos indicus). La determinación de genotipos se realizó mediante la metodología polimorfismo conformacional de cadena sencilla. Se realizó un ensayo de desafío infeccioso in vitro, para estimar la capacidad de los macrófagos bovinos para controlar la sobrevivencia bacterial, lo que permitió definir los individuos como resistentes o susceptibles. Los resultados sugieren una asociación significativa del SNP4 (p = 0,0506) con la variación para el fenotipo de susceptibilidad, pues se encontró el genotipo homocigoto (BB) en alta frecuencia en animales catalogados como resistentes y el genotipo heterocigoto (AB) en alta frecuencia en animales catalogados como susceptibles y en animales con títulos de anticuerpos anti Brucella abortus.
Adición de proteínas del plasma seminal ovino durante la congelación del espermatozoide y efectos sobre su motilidad y viabilidad
Authors: Cardozo Jaime Antonio , Grasa Patricia , Muriño María Teresa , Cebrián José Álvaro
Published: August 2016

Este estudio se adelantó para evaluar el efecto de la adición de proteínas del plasma seminal de cordero en la criopreservación sobre la motilidad e integridad de la membrana espermática, y los cambios en el perfil electroforético de las proteínas de la membrana espermática inducidos por la criopreservación. Se usaron eyaculados de ocho corderos adultos de la raza rasa aragonesa, se les determinó su viabilidad y motilidad espermáticas y posteriormente se sometieron a un procedimiento de congelación. Las proteínas se separaron por el método de electroforesis en geles de acrilamida en dos dimensiones. Se obtuvo un mejoramiento significativo (p < 0,05) en la calidad del semen congelado, cuando se adicionaron proteínas del plasma seminal. El análisis bidimensional comparativo entre el semen fresco y el congelado evidenció la pérdida de 8 puntos de proteína en el espermatozoide descongelado. La concentración de un punto de proteína de membrana espermática, de bajo peso molecular (punto 2), fue más alta (p < 0,05) en el espermatozoide descongelado al que se adicionaron proteínas del plasma seminal. Se encontraron correlaciones entre algunos puntos de proteína y la motilidad y viabilidad espermáticas, lo cual sugiere que pueden jugar papeles importantes en el mantenimiento de la integridad y funcionalidad del espermatozoide. Se puede concluir que la adición de proteínas del plasma seminal en la congelación mejora la integridad del espermatozoide descongelado, y que la criopreservación del semen de cordero produce variaciones en la composición de las proteínas de membrana.
Evaluación de dos marcas comerciales de la feromona sexual de Spodoptera frugiperda Smith (Lepidoptera: Noctuidade) en el Tolima, (Colombia)
Authors: Agudelo Jhon Alexander , Amaya Oscar Santos , Garramuño Elizabeth Aguilera , Argüelles-Cárdenas Jorge
Published: August 2016

Se evaluó la eficiencia y la vida media en campo de dos feromonas de atracción sexual para machos adultos de S. frugiperda en el departamento del Tolima, Colombia durante el primer semestre del año 2008. Las feromonas correspondieron a las marcas comerciales ChemTica de origen costarricense y Pherobank de origen Holandés. Se utilizó un diseño de bloques al azar con tres tratamientos (dos marcas de feromonas y un testigo) y 4 repeticiones (bloques), para un total de 12 unidades de muestreo. Las trampas se instalaron en un cultivo de algodón al inicio de la etapa reproductiva y fueron evaluadas tres veces por semana. Se utilizó un análisis de varianza para detectar diferencias entre tratamientos y la prueba de comparación de medias de Tukey para caracterizarlos. Se encontraron diferencias significativas entre tratamientos (P≤0,05), siendo la marca ChemTica que presentó el mejor comportamiento, con un promedio de captura de 25,79 adultos por trampa por día, en comparación con 1,58 de Pherobank y 0,417 del control. Los resultados fueron consistentes en todos los bloques y persistentes en el tiempo. La vida media de la feromona ChemTica fue de 50 días en campo a 30°C, con 23,3 mm de pluviosidad y una velocidad de los vientos predominantes del sur y sur oeste a 2,5 m s-1.
Microorganismos que mejoran el crecimiento de las plantas y la calidad de los suelos. Revisión
Authors: Pedraza Raúl , Teixeira Kátia-R.S. , Scavino Ana Fernández , De Salamone Inés García , Baca Beatriz , Azcón Rosario , Baldani Vera , Bonilla Ruth
Published: August 2016

El presente artículo surge de la revisión de la teoría y temas prácticos desarrollados durante el curso”Caracterización y contribución de las plantas que promueven el crecimiento de microorganismos en la sostenibilidad de la agricultura”, llevado a cabo en el Laboratorio de Microbiología de Suelos de la Corporación Colombiana de Investigación Agropecuaria (Corpoica), ubicado en Mosquera (Cundinamarca), Colombia, en julio de 2010. Esta actividad fue desarrollada en el marco de la Red Dimiagri que incluye a investigadores de Argentina, Brasil, Colombia, España, Guatemala, México y Uruguay, reunidos en una acción de coordinación financiada por el Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo (Cyted). Los aspectos inherentes al crecimiento y la sanidad vegetal, el sistema radical, el suelo circundante (rizósfera), los microorganismos asociados en ese sistema y su contribución al manejo sustentable del complejo suelo-planta fueron analizados en este trabajo. También se abordan temas como la biodiversidad microbiana y su efecto en la calidad del suelo; el ciclado de nutrientes del suelo por acción microbiológica; la importancia de los microorganismos en la promoción del crecimiento vegetal y su utilización biotecnológica como alternativa para favorecer la sustentabilidad y calidad de los suelos. Además se pretende interiorizar en los conceptos relacionados con el consorcio suelo-planta-microorganismo y el objetivo de mitigar el impacto ambiental negativo causado por el uso excesivo de insumos químicos en los cultivos agrícolas, mediante la utilización de microorganismos promotores del crecimiento vegetal, que incluyen tanto a bacterias como a hongos benéficos asociados con las raíces de las plantas.
Asociación simbiótica entre hongos micorrízicos arbusculares y el sistema radicular de plántulas de cacao (Theobroma cacao L.): efecto de la formononetina y la disponibilidad de fósforo en el suelo.
Authors: Cuadros Guillermo Andrés , Gómez Raúl
Published: August 2016

La simbiosis entre plantas de cacao y hongos micorrízicos arbusculares (HFMA) confiere beneficios nutricionales y competitivos a la planta, especialmente en condiciones de baja disponibilidad de nutrientes. Se evaluó tres niveles de fósforo (5, 20 y 40 ppm) y la presencia o ausencia de isoflavonoide formononetina. El nivel 14 ppm de P sin el isoflavonoide fue el tratamiento testigo. Todos los tratamientos fueron inoculados con HFMA a excepción del tratamiento control. Se utilizó un diseño completamente al azar y se determinaron caracteres morfológicos de la planta a los 70, 110 y 150 días después de la inoculación. Los resultados no mostraron respuesta diferencial a los caracteres morfológicos de la planta por la disponibilidad del isoflavonoide durante los tres muestreos. La longitud radicular presentó diferencias significativas en los muestreo (70, 110 y 150 días de inoculación), siendo esta respuesta dependiente de la disponibilidad de P y la interacción plantamicorriza. El número de esporas mostró diferencias entre los muestreos de 110 y 150 días de inoculación en presencia y ausencia del isoflavonoide, sugiriendo una rápida estimulación en el establecimiento de la relación simbiótica por la formononetina en el proceso de germinación y formación de estructuras fúngicas.
Evaluación de gramíneas y leguminosas forrajeras como coberturas y su influencia en el control de malezas en el establecimiento de cítricos en el piedemonte del Meta.
Authors: Orduz-Rodríguez Javier Orlando , Calderón Claudia Liliana , Bueno Guillermo , Baquero P. José Eurípides
Published: August 2016

Con el propósito de desarrollar sistemas de manejo sostenible para el cultivo de cítricos en el trópico bajo, se evaluó el comportamiento de dos especies de leguminosas y cuatro gramíneas en comparación con el control mecánico y químico, en condiciones de terraza alta del Piedemonte del meta. se establecieron las especies Desmodium ovalifolium cv. Maquenque, Paspalum notatum, Brachiaria dictyoneura cv. Llanero, Arachis pintoi CIAT 18744, Brachiaria brizantha cv. Toledo y Panicum maximum CIAT 36000, y los controles herbicida, guadaña + herbicida. El área experimental se estableció en las calles de un cultivo de naranja Valencia del Centro Investigación La Libertad de Corpoica en Villavicencio. Se evaluaron las variables porcentaje de cobertura y producción de biomasa durante dos años, y resistencia a la penetración (RP) al finalizar el experimento. Para el análisis de los resultados se utilizó estadística descriptiva, análisis de varianza y comparación de medias con la diferencia mínima significativa (DMS). Los mayores porcentajes de cobertura del suelo se obtuvieron con A. pintoi, P. maximun y B. dictyoneura, con 96,98%; 95,98% y 94,5%, respectivamente. En los 753 días después de establecido el ensayo, se encontró que P. maximum, produjo 20.053 kg ha-1 de materia seca, seguido de B. brizantha con 13.624 kg ha-1, los cuales superaron estadísticamente a otros tratamientos. Por otro lado, A. pintoi fue la especie que generó la menor RP seguida de D. ovalifolium. Los resultados obtenidos señalan ventajas en el uso de coberturas en la fase de establecimiento del cultivo de cítricos en cuanto al control de malezas, disminución de la resistencia a la penetración y protección del suelo a la erosión por escorrentía.
Diagnóstico de la fertilidad química de los suelos de los municipios de Granada y Silvania para la producción de uchuva en Cundinamarca
Authors: Roveda Gabriel , Peñaranda Andrea , Ramírez Margarita , Baquero Irma , Galindo P. Ricardo
Published: August 2016

La nutrición de las plantas de uchuva es determinante para obtener un alto rendimiento del cultivo y garantizar el nivel de calidad del producto para exportación. Con el fin de caracterizar la fertilidad química de los suelos de las zonas productoras de uchuva en Cundinamarca, se realizó un muestreo en dos de los principales municipios productores, como son Granada y Silvania. Para tal fin se seleccionaron 30 fincas en las cuales se realizó el muestreo de suelos y la posterior caracterización química y su relación con el contenido de nutrientes disponibles para las plantas. Se hizo la comparación de municipios con el fin de determinar la conveniencia de un manejo similar o, en caso contrario, específico por zona. Se encontraron diferencias significativas entre los dos municipios, relacionadas especialmente con el contenido de materia orgánica en el suelo, pero además se observaron serios problemas de desbalance de cationes y alta acidez, que requieren una planificación adecuada de la fertilización. Además, los altos niveles de micronutrientes Mn y Cu pueden ser limitantes para el cultivo de uchuva. Se analizaron los componentes principales asociados a la fertilidad de los suelos y se hicieron recomendaciones generales por zona que deben ajustarse a nivel de finca.
Efectos de las condiciones ambientales sobre el comportamiento ingestivo en bovinos de carne en un sistema intensivo en el Valle del Sinú
Authors: Suárez Emiro , Reza Sony , Díaz Eliecer , García Fredy , Pastrana Iván , Cuadrado Hugo , Espinosa Manuel
Published: August 2016

Incrementos en la temperatura ambiental y la humedad relativa, unidas al efecto de la radiación solar, ocasionan pérdidas en el bienestar animal, afectando la conducta ingestiva y la productividad animal. Por ello el objetivo de este estudio fue analizar las relaciones entre las variables atmosféricas, como temperatura del aire, humedad relativa, velocidad del viento y radiación solar, con los tiempos de pastoreo y de rumia de bovinos cebú comercial. La investigación se llevó a cabo durante 96 días, entre julio-octubre de 2010, en el C.I. Turipaná de Corpoica (Cereté, Colombia). Bovinos machos enteros (27), con peso promedio 314 ± 29 kg, pastorearon en un área de 18 hectáreas, establecidas en Panicum maximum cv. Mombasa, Cynodonnlem fluensis y Brachiaria híbrido cv. Mulato II, sin disponibilidad de sombra. Se realizaron ocho evaluaciones durante 8 días dentro del periodo experimental de las variables atmosféricas e ingestivas y las anotaciones se hicieron en un lapso de 12 horas continuas (6:00 AM a 6:00 PM). Los resultados resaltan que al aumentar la temperatura del aire, humedad relativa y la radiación solar, disminuyó el tiempo de pastoreo y aumentó el tiempo de rumia, mientras que al aumentar la velocidad del viento se incrementó el tiempo de pastoreo y disminuyó el tiempo de rumia. Los resultados obtenidos indicaron que la temperatura del aire, humedad relativa, radiación solar y velocidad del viento, presentaron una influencia directa sobre el comportamiento ingestivo de los bovinos de carne manejados en sistemas intensivos (sin sombra) en el Valle del Sinú.