bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies of Microwave Electromagnetic Field Influence on Adhesion Strength of the “Matrix-Fiber” Contact Zone on the Example of the Elementary Cell of a Certified Polymeric Composite Material
Authors: Zlobina I.V. , Bekrenev N.V. , Muldasheva G.
Published: May 2020

The strength characteristics of polymer composites (PCM) reinforced with fibers of various nature largely depend on the adhesion strength of the components in the matrix-fiber contact zone, determined by the mechanisms of their adhesive interaction. The strength of the bonds in the contact zone depends on the transfer of the load from fiber to fiber through the matrix layer. Taking into account the order and greater strength of the reinforcing fibers in tension, compared with the matrix material, the adhesion of the PCM components has the greatest effect when the material is perceived as transverse to the direction of the fiber loads, which usually occurs in bending and interlayer shear. In the latter case, the strength of the material several times less, which determines the importance of increasing the strength of the adhesive interaction, which requires comprehensive studies and an adequate description of its mechanisms.
An experimental study of the adhesion strength in the matrix-fiber contact zone after short-term exposure to a microwave electromagnetic field with different energy flux densities on the PCM physical cell model, represented as a basalt fiber bundle placed in ED-20 epoxy resin, was performed. It has been established that exposure to a microwave electromagnetic field with an energy flux density of (17-18) x104 μW/cm2 for 1-2 minutes leads to an increase in adhesion relative to the source material by no less than 32%. This method can be used as a basis for the development of technologies for increasing the strength of the interlayer shear PCM, reinforced by fibers of various nature. To clarify the mechanisms of the obtained results, it is advisable to conduct a study of the micro-and nanostructures of the “matrix-fiber” contact zone using electron and atomic-force microscopy and its phase composition..
About Communication of the Comparative Properties Plasticized PVC Compositions and Quantities of Additives Used
Authors: Maskova A.R. , Yarmuhametova G.U. , Savicheva Yu.N.
Published: May 2020

In work influence of the main additives (a heat stabiliser, softener, an excipient) on physicomechanical properties of compositions on the basis of polyvinylchloride (PVC) is studied. It is noted that increase in content of additives in a system in the stated quantities leads to change of Shore hardness of A. and melt flow rate. The functional interrelation between the applied additives and properties of plastic compounds is established. The reliability of the received mathematical model and its applicability for prediction of properties of PVC compositions depending on structure of a compounding is proved.
Influence of Shungite Modificator on Technological Properties of Polymeric Glue Based on Urea-Formaldehyde Resin
Authors: Panov Nikolai Gennadievich , Vasilyev Sergey Borisovich , Kolesnikov Gennady Nikolaevich
Published: May 2020

Previously it has been experimentally established that modification of polymeric glue on the basis of urea-formaldehyde resin by adding shungite powder leads to improvement of physical-mechanical properties of wood-particle boards. The goal of the investigation was to establish the influence of the shungite powder, consisting of particles in the size from 50 to 100 nanometers, on such technological properties of glue, as duration of gelatinization and viscosity. It was established: the shortest duration of gelatinization for glues was achieved with shungite addition of 10%; the lowest viscosity depends on the composition of the glue and was achieved with shungite addition from 5 to 10%.
Friction Stir Welding in the Aircraft Production
Authors: Kuritsyn D.N. , Siluyanova M.V. , Kuritsyna V.V.
Published: May 2020

The paper presents the results of experimental development of the technology of friction stir welding to obtain a nonseparable connection of a special aerospace aluminum, titanium and magnesium alloys, high-temperature steels. Regularities and models of heat balance in the welding zone have been determined, which make it possible to predict the technological possibilities of high-speed friction welding. It is established that high-speed friction welding by mixing allows to obtain a high-quality connection at lower loads on the design of the equipment. On the basis of studies of macro-and microstructure, microhardness, level of residual stresses and strength tests, technological recommendations on the choice of welding conditions and conditions were obtained. Presented of experimental and industrial development of special equipment, high-speed friction welding, design and manufacturing of high hardness tools of complex spatial shapes for welding aircraft materials.
The Study of Heat Exchange Process between High-Temperature Liquid Metal Coolant and Liquid Steel during Crystallization
Authors: Neshporenko Evgeny , Kartavtsev S. , Matveev S.
Published: May 2020

The paper presents the results of mathematical research of process of heat exchange between liquid metal coolant and molten steel. Research of process of heat exchange between liquid metal coolant and crystallizing the steel at temperatures above 1773 K allowed to determine parameters such as: the intensity of heat transfer for mutual parallel flow and counter flow, the minimum required length of heat exchange zone; the coolant that provides the best energy performance.
Optimization of Technological Parameters of the Process for Obtaining a Strip by the Combined Method of Metal Casting and Deformation
Authors: Chernomas V.V. , Khimukhin S.N. , Khimukhina T.S.
Published: May 2020

In order to obtain high-quality metal products with the desired properties (process stability) using the combined methods of metal casting and deformation, it is necessary to take into account the specific parameters of this process and the fact that the metal in the crystallizer stays simultaneously in several physical states: liquid, liquid-solid, solid-liquid and solid. Structurally, the mold consists of four walls moving relative each other along a given sophisticated trajectory. The object of the research is the production technology from non-ferrous alloys using the combined method of continuous casting and metal pressure treatment. The thermal processes occurring in the mold of a continuous horizontal metal casting and deformation installation (CHMCDI) during the formation of metal products have been examined as a research subject. The methods of physical modeling of the thermal processes which take place in the system “crystallizing metal-tool deformation” under different conditions of the mold cooling (using closed-perforated tubes and straight-flow tubes) have been used. Subsequent data processing of the full factorial experiment using the least square method as well as solving the optimization problem by using the Pareto principle of optimality made it possible to determine the optimal parameters for the process of obtaining metal products from aluminum alloys (TV = 40 oС; рv = 0.7 kg / cm2; SR = 5.8), which have been confirmed by the results of the experimental test on obtaining the strip from technical aluminum AD0 strip with a cross section of 40–12 mm.
Dome House Insulation Systems
Authors: Shokodko E. , Bobrova Ekaterina Yu. , Zinovyeva E. , Zhukov Alexey D.
Published: May 2020

The article presents the results of studying the possibility of using the insulation systems in the structures of rural buildings of various functional purposes, including the creating the multifunctional objects. A vegetarium dome house is considered, which unites a living area and greenhouses. The planning solution of the multipurpose domed house involves the formation of the effective insulation systems for the interior walls, protecting the living space of the interior from the heat-moisture and phytoaggressive features of the greenhouse exterior. A comparative analysis of possible heat-, water-and vapor-insulating materials for an insulating membrane has established the expedience of using the rolled foam-polyethylene fixed by an adhesive method on the external surfaces of the internal walls. Experimental studies have established that polyethylene foam with an average density of 18–20 kg/m3 has the following characteristics: the diffusion moisture absorption without any coating is 0,44 kg/m2; the diffusion moisture absorption with a metalized coating is 0,37 kg/m2; water absorption upon partial immersion in water for 24 hours is 0,013 kg/m2; volume water absorption with full immersion in water for 28 days is 0,96%. The nature of the destruction of the contact surface “foam polyethylene-metal” is cohesive in the adhesive layer, and the destructive stress is 12–17 kPa. A special feature of the polyethylene foam is the possibility of creating a jointless coating with minimal diffusion characteristics and with minimized cold bridges. The jointless cover is formed by combining the roll material into a lock, followed by hot air welding.
Estimation of Rheological Properties of Ash Silicate Paints
Authors: Loganina Valentina I. , Mazhitov Yerkebulan B.
Published: May 2020

Information provided on the color of paint coatings on the mortar substrate, depending on the type of pigment in accordance with the RAL color file. It is shown that presence of glycerin in the composition of the sol of silicate paint promotes an increase in the cohesive strength of coatings, an improvement in the filling of paint, and an improvement in the quality of the appearance of coatings. Information is given on the rheological properties of a silicate paint sol with the addition of glycerin depending on the pigment content. It has been established, that the introduction of glycerin into the paint formulation leads to an increase in the values of the critical volume concentration of the pigment (filler). A model for changing the viscosity of paint from a pigment volume concentration (filler) is proposed.
Laboratory Study of Tribological Characteristics of Innovative Lubricant Coolants
Authors: Gaidar S.M. , Pydrin A.V. , Karelina M.Yu. , Gaidar M.S. , Sukhodolya A.V.
Published: May 2020

In the article researches mathematical models that ensure effectiveness of use combined methods for parts processing. The use of combined processing methods is always associated with the search for technological compromise and boils down to technical and economic indicators comparative assessment. In this case, it is necessary to rely on mathematical models that objectively reflect manufacturing parts technological processes. Mathematical methods and models for optimizing production processes for manufacturing parts that are applicable in combined methods for processing parts are a complex formalized scientific abstraction that describes production functioning process at all stages of its implementation. In the synthesis of various processing methods, it is necessary to ensure that a number of conditions are met that determine necessary and sufficient conditions for implementing feasibility a particular technology in the combined method of processing parts. Multiple regression analysis methods allow minimizing experiments number in mathematical model determining which adequate to processes under study and form the baseline data for the transition from multi-factor to multi-criteria models. Using this approach, it is necessary to determine objective function optimal values parameters and influence factors in each specific technological process, which will allow us to bring the uncertainty removal in the processing materials technology to a new qualitative level.
New Energy-Consuming Carbon Materials Derived from Hydrolytic Lignin
Authors: Nikolenko Yury M. , Tsvetnikov Alexander K. , Ustinov Alexander Yu. , Sokolov A. , Ziatdinov Albert M.
Published: May 2020

Hydrolytic lignin (HL) has been used in manufacturing of graphitized carbon via HL one-step physical activation. It was found that the layered carbon products of pyrolysis of hydrolytic lignin (AHL) at different temperatures may be used as cathode materials in primary current sources. The galvanostatic discharge of lithium battery at a current density of 100 μA/cm2 between 3.0 and 0.5 V shows that the specific capacity of thermally activated derivative is equal to 845 mA·h/g, while the untreated lignin yields only 190 mA·h/g. The fluorination of both the lignin and its thermally activated form results in higher operating voltage of lithium battery, as seems, due to the involvement of fluorine bound to carbon in electrochemical process. Some fluorinated AHL samples show the promise of their use as supercapacitor electrodes.
Application of Experiment Planning Methods in Researching of Reinforced Concrete Constructions Corrosion Process
Authors: Kuznetsov A.A. , Bryukhova A.S. , Volkova N.V.
Published: May 2020

The article discusses statistical methods of experiment planning for determining the significance of influencing factors on the course of the corrosion process. The application of the proposed method in conjunction with spectral monitoring methods is shown. Mathematical models are presented that allow to investigate the corrosion process with various combinations of influencing factors. The response surface of the dependent variable on the most significant factors is constructed. The conclusion is made that spectral methods can be used to determine the corrosion state of reinforced concrete structures.
On the Connection of Cascade-Probability Function on the Formation of Primary-Knocked on Atoms for Ions Taking into Account Energy Losses with a Boltzman Equation
Authors: Voronova Nataliya A. , Kupchishin Anatoliy I.
Published: May 2020

The integral-differential equation of the cascade process for ions was solved using the Laplace transform and the method of successive approximations, taking into account the energy loss during the formation of primary-knocked-on atoms (PKA) in a one-dimensional model of an elementary atom. It is shown that the solution includes a cascade-probability function (CPF) for these particles. The main properties of CPF are considered and its graphical dependencies on the depth of registration are presented. It is shown that with the specific ionization loss coefficient k = 0, the FQM turns into the simplest cascade-probability function. When λ0→ 0, λ0→∞ and n→∞, the KV-function is equal to 0. The sum of the probabilities for all possible collisions from 0 to ∞ is 1. As the detection depth h increases, for all values of n, the CRF increases, reaches a maximum and then decreases . With increasing n, the curves shift to the right.
Approximate Engineering Model of Ferritic-Pearlitic Steel Constructions Resource Evaluation
Authors: Molokov K.A. , Novikov V.V. , Vasilchenko N.P. , Turmov G.P.
Published: May 2020

In the constructions and weld seals microdefects while repeated stress lead to metal structure damage, low-cycle and high-cycle fatigue, and cracks dissemination. The calculation method of operating life estimate presupposes a microcrack development hypothetical speed application. This speed in many cases is unknown. Initial speed determination suggested in this work is based on endurance limit values design analysis when considering a combined problem for the first two sections of fatigue failure kinetic diagram.
The Use of X-Ray Diffraction Peaks Profile Analysis to Define the Structural Condition of Elastically Stressed 09G2S Steel
Authors: Gulyaev V.P. , Petrov P.P. , Stepanova Ksenia V.
Published: May 2020

By using X-ray diffractometry, it was determined how short-term stresses, being within the limits of the offset yield strength σs, influence changes in the diffraction line profile characteristics resulting from static tension in plate specimens of 09G2S (09Г2С) structural steel. Microstructural changes in the surface of 09G2S steel specimens considered in this work were studied at different levels of elastic stress. The special aspects of changes in the diffraction line profile characteristics are presented and discussed, specifically, a broadening of the profile maximum half-width (B), as a response to the external mechanical impact on the surface layers.
Strain-Energy Criteria for the Destruction of Ideal Rigid-Plastic Bodies
Authors: Kozlova O.V. , Khromov A.I.
Published: May 2020

The process of destruction of cylindrical samples under uniaxial tension is described taking into account changes in the geometry of the sample. An approach is formulated to determine the failure constants in the form of invariant characteristics based on standard mechanical tests under conditions of axisymmetric deformation.
Échanges homme-animal : « du bon, du moins bon ». Le point de vue du médecin
Authors: Bricaire François
Published: May 2020

La relation entre l’Homme et l’animal est une constante, un élément essentiel puisque nous vivons en permanence l’un avec l’autre. Cette relation plus ou moins proche s’exprime par de nombreux aspects, dont une grande partie se rattache directement ou indirectement à la Santé. Toute relation comporte des aspects positifs mais aussi des points négatifs. Sont donc abordés ici, ces différents points, le bon pour l’Homme et pour l’animal, le moins bon également pour les deux protagonistes.
Microbiologie et coquillages : des enjeux et des développements futurs
Authors: Le Guyader Soazick F. , Garry Pascal , Ollivier Joanna , Piquet Jean-Côme
Published: May 2020

La salubrité des coquillages est considérée depuis fort longtemps comme un problème de santé publique. La mise en place d’une réglementation basée sur un indicateur bactérien de contamination d’origine fécale a permis de diminuer significativement les épidémies d’origine bactérienne. Cependant, les épidémies de gastroentérites virale dues à la présence de norovirus issus de rejet humains persistent. Des travaux de recherche nous ont permis de mettre en évidence que l’huître n’est pas simplement un filtre passif mais est capable de sélectionner certaines souches virales, via

la présence de ligands spécifiques, très proches des ligands observés chez l’homme pour ces mêmes virus. Les développements en cours en lien avec l’utilisation des outils de metagénomique, vont nous permettre de mieux appréhender le devenir de certains micro-organismes pathogènes humains après leurs rejets dans l’environnement côtier.
Photo-toxicité rétinienne et pollution lumineuse : intérêts et apports de l’ophtalmologie vétérinaire
Authors: Rosolen Serge Georges , Berdugo Polak Marianne
Published: May 2020

Retinal photo-toxicity & light pollution : interests & contribution of the veterinary ophthalmology

Two reports of the French ANSES (Agence Nationale de sécurité sanitaire de l’alimentation, de l’environnement et du travail) highlighted the potential risks of exposure to lighting systems using light-emitting diodes (LED), especially because emitting short wavelengths (blue light), on the human, animal and environmental healthes. Two dangers have been identified : the retinal phototoxicity and the biological circadian rythms deregulation (chrono-disruption). Acute exposure to intense light induces retinal cell death that can lead to blindness. Chronic exposure to low-intensity phototoxic light accelerates the aging process of retinal tissues, that can lead to degenerative diseases such as Age-related Macular Degeneration (AMD). The authors of these reports considered that it would be appropriate to evaluate the extrapolation to humans of the results obtained in laboratory animals. The purpose of this article is to illustrate the contribution that veterinary ophthalmology could provide through relevant clinical observations in companion animals, considered as animal-patients, and in livestock collectively subjected to artificial light creating bright environments imposed by farming practices, considered to be – because of their large numbers – environmental sentinels. The deleterious effects of light are summarized in a section devoted to the laboratory animal and then the main methods of clinical diagnosis of retinal dysfunction, common to human and veterinary ophthalmology, are described. Obviously, the concept of uniqueness of health (One health, One medicine) applies to this problem of light pollution : human and veterinary medicine must work together for a systemic appreciation of human-animal-environment relationships.
Šest budističnih simbolov: analiza poetične podobe Budovega razsvetljenja iz dinastije Song
Authors: Vrhovski Jan
Published: May 2020

V članku se osredotočam na šest med seboj povezanih budističnih simbolov, ki se pojavljajo v poeziji Su Shija, uradnika in pesnika iz dinastije Song. Skozi analizo ozadja posameznih ikonografskih motivov in budističnih simbolov, ki se navezujejo na ikonografsko podobo Budovega razsvetljenja, se nam razodevajo njihove povezave z delom budističnega kanonskega izročila, ki se v fragmentih navezuje tako na prvotno izročilo kakor tudi na avtohtone elemente iz kitajske tradicije. Obravnava nastanka in rabe budističnih simbolov pa nam lahko posledično obelodani tudi način, s katerim so budistični simboli skozi stoletja postopoma vstopali v domeno splošno rabljenega pesniškega izrazja in tako sooblikovali izraznosti podob pesnikovega notranjega sveta.
Li Zehou’s Reconception of the Classical Confucian Concepts of Autonomy and Individuality: With a Focus on Reading the Analects Today
Authors: Jia Jinhua
Published: May 2020

Li Zehou coins the term “guanxi-ism” (relationalism) to confirm the Confucian self with its two aspects of social relations and independent character, while elaborating the classical Confucian notions of individuality, autonomy, and self-realization in his many works, especially in Reading the Analects Today. Li argues that Confucius interprets external ritual as a person’ own internal intention and drive, and as a result elevates social and ethical regulations as personal emotions and the autonomous power of decision. With a certain transformative construction, Li expects that this Confucian project can be efficiently applied in developing humanity and reconstructing the cultural order in today’s world.
Toward a Brillant Diversity
Authors: Johnson Chrystal S , Hinton Harvey
Published: May 2020

This essay puts forward a theoretical argument in support of culturally consonant character education. Character education supports the moral and civic development of youth in the United States (US), and it remains popular with all stakeholders. Majority group members often are unmindful of the significance and span of cultural distinctiveness of minorities. Rather, majority group members consciously or unconsciously advocate assimilation and adherence to universal virtues, chiefly in the field of character education. Cultural-historical conditions, as features of the moral development process, tone the agency and negotiation of character education. To that end, this essay employs Charles Mills’ The Racial Contract (1998) to not only account for the moralities of exclusion, but put forward a character education philosophy that accounts for cultural distinctiveness.
Resisting Assimilation to the Melting Pot:
Authors: Calderon Berumen Freyca
Published: May 2020

The melting pot metaphor suggest that people from different backgrounds come to the United States and through the process of assimilation adapt to a new lifestyle integrating smoothly into the dominant culture. This article argues that immigrants from diverse cultural and ethnic groups that try to keep some of their cultural traditions may encounter conflict when trying to adapt to their life in the new context. The author contends for a cultural curriculum of the home endorsing family cultural values and traditions tha is overlooked by schools and educators, disregarding its potential for enhancing children’s learning process and academic achievement.
Timeless Learning: How Imagination, Observation, and Zero-Based Thinking Change Schools
Authors: Morris Chelsea T , Chapman Lindsey A
Published: May 2020

This review provides a broad discussion related to how the authors of Timeless Learning: How Imagination, Observation, and Zero-Based Thinking Change Schoolsspeaks to ongoing institutional practices that limit and oppress learner’s leadership, imagination, and self-exploration. The book’s focus on the biodiversity of learning is highlighted within the review as a necessary strength to the humanization of students and to seeing the value of student-driven learning.
Influence of Teacher's Characteristics on Civic Education Implementation in Nigeria
Authors: Obiagu Adaobiagu Nnemdi
Published: May 2020

There is evidence of dissatisfaction of millennials with democracy and rising populist support for non-democratic forms of governance and nationalism among them. This presents challenges for civic education implementation and calls for promotion of constructivist civic teachers. Motivated by the need to apply deep civic education in inhibiting non-democratic beliefs and promoting viable strong democracy through active citizens, the present study employed a descriptive survey to investigate the influence of teacher's gender and educational background on teacher's implementation of civic education using data collected from randomly selected 16 secondary school civic education teachers and 320 secondary school students comprising 20 students of each teacher participating in the study. Two instruments were used for data collection on teachers’ initial and continuous training in civic education, and teachers’ implementation of civic education. Two research questions answered using mean and standard deviation, and three null hypotheses tested at 0.05 level of significance using correlation, Mann-Whitney and Kruskal-Wallis H Test guided the study. The findings showed that a high number of civic teachers did not receive prior training in civic education as well as do not engage in lifelong learning or continuous training in civic education and teaching practice. Civic teachers do not also actively engage students in civic instructions. A positive relationship exists between teacher’s training in civic education and teacher’s implementation of civic education. While civic teachers’ educational background did significantly influence implementation of civic education, gender did not. The findings were associated to a number of factors including lack of cognition of the power of civic education in constructing, reconstructing and transforming (dys)functional societal ideologies. Promotion of lifelong learning among teachers, training of teachers in civic contents and methods, and utilization of ICT for instructional purposes were recommended.
The Impact of demographic factors on pre-service teachers’ perception of Educational Research: Findings from a private university
Authors: Manu Jacob , Owusu-Ansah Christopher M.
Published: May 2020

The current study sought to identify the effects of democratic factors on the perception of pre-service teachers (with diploma as their highest level of education) on the teaching and learning of the Educational Research course during the fall 2017 semester in one of the private universities in Ghana. With a survey research design, three hundred and twenty (320) pre-service teachers, who were enrolled in the fall 2017 sandwich programme, were randomly sampled to participate in the study. The findings revealed significant differences between male and female pre-service teachers perception of the teaching of research, relevance of research and their statistics anxiety. Also, the age independent variable indicated a significant difference on the statistics anxiety construct only whereas the other two constructs were not significant. There were significant correlations among age, years of teaching, and statistics anxiety. The implication of the study for practice is discussed.
Historical Fiction Picture Books
Authors: Wadham Rachel Lynn , Garrett Andrew P. Garrett , Garrett Emily N.
Published: May 2020

Historical fiction picture books represent a small subset of titles in the broader scope of the format. However, these books are important to both readers and educators. As books are used in educational settings it is critical to assess their effectiveness in helping teach children.  This is especially true of historical fiction which generates its own unique challenges.  To deeply assess historical fiction picture books we gathered and analyzed a sampling of 126 titles to assess trends in the genre. We found that there were multiple conflicts between the genre and format. There were many books in the sample that struggled with directing the content to a young audience, giving a accurate portrayal of race issues, and maintaining general authenticity and accuracy in the writing. There were also some notable examples of historical picture books that did not display these faults, showing that with the right content and approach, historical fiction picture books have the potential to be invaluable tools for teaching children.
Histórico da Criação do MuArq – Museu de Arqueologia da Universidade Federal de Mato Grosso do Sul
Authors: Martins Gilson Rodolfo
Published: May 2020

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Arqueologia das Unidades de Defesa
Authors: Albuquerque Marcos A. Gomes de Mattos
Published: May 2020

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Bioarqueologia e Antropologia Forense
Authors: Souza Sheila Maria Ferraz Mendonça de
Published: May 2020

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Arqueofauna Resgatada no Sítio Arqueológico Maracaju 1 (MS): Implicações no Estabelecimento dos Padrões de Subsistência e Mobilidade das Populações Humanas Pretéritas Locais
Authors: Pacheco Mirian Liza Alves Forancelli , Martins Gilson Rodolfo
Published: May 2020

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Cenários do Pantanal: o gado, os peões e as comitivas
Authors: Brum Eron
Published: May 2020

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Curumiaí: uma povoação no caminho de Xerez
Authors: Freire Paulo Cezar Vargas
Published: May 2020

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Imagens urbanas assombrosas: controle social nas cidades brasileiras da Belle Epoque
Authors: Martins Júnior Carlos
Published: May 2020

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A cidade de Rubem Braga: apontamentos sobre o espaço urbano em crônicas de Rubem Braga
Authors: Antonio Luciano
Published: May 2020

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Monumento e memória no espaço urbano carioca: O exemplo do Monumento Nacional aos Mortos da Segunda Guerra Mundial
Authors: Figueiredo Olga Maria
Published: May 2020

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Pineapple growth and yield response to fertilizer and drip irrigation management
Authors: Acevedo Melissa , Román-Paoli Elvin , Román-Pérez Félix M. , Valencia Elide , Tirado-Corbalá Rebecca
Published: May 2020

Pineapple [Ananas comosus (L.) Mere] is an important fruit crop cultivated in many tropical countries. This fruit crop requires large amounts of nitrogen (N) and potassium (K) to maximize yield. Although pineapple has low water requirements, extended drought can affect yield. Two experiments were conducted to study the effects of fertilizer application methods and drip irrigation management on pineapple yields. Pineapple cultivars MD-2 and Cabezona were planted at Isabela and Lajas, Puerto Rico, respectively. Fertilizer and irrigation treatments included: i) Controlapplication of 896 kg/ha of a granular fertilizer (12-6-10-3) at two, five and nine months after planting; ii) FS-R- application of 150-150-120-45 kg/ha at planting plus 20 foliar applications of urea and potassium sulfate (50 kg/ha) every three weeks, rainfed; iii) FS-DI- application of 150-150-120-45 kg/ha at planting plus 20 foliar applications of urea and potassium sulfate (50 kg/ha), drip irrigation applied every three weeks; iv) FERT- application of 150-150-120-45 kg/ha at planting, but urea and potassium sulfate (50 kg/ha) were applied throughout fertigation; and v) CRF- same amount of nutrients as FS-R but N was applied as a controlled release fertilizer every six months. At Isabela, treatment FS-R produced the highest fruit weight (2.5 kg per fruit) and 1.5% of N in tissue, but did not differ significantly from FS-DI and CRF. Plants under CRF registered the highest Brix (15.8°). Although foliar fertilizer tended to produce higher yields, controlled release fertilizer is recommended because it eliminates the need for frequent foliar application without compromising yield.
Producción y distribución de materia seca en lerén [Calathea allouia (Aubl.) Lindl]
Authors: Puran Bridgemohan
Published: May 2020

El lerén [Calathea allouia (Aubl.) Lindl] es un tubérculo tropical con potencial para procesamiento y como un sustituto para las castañas de agua. La sombra afecta la tasa fotosintética del cultivo por lo que el crecimiento y los rendimientos varían. Existe poca información en cuanto al mejoramiento agronómico de este cultivo. Este estudio se estableció para entender cómo, a través de la manipulación de la luz, densidad poblacional y factores nutricionales, la producción y distribución de los asimilatos afecta el rendimiento del cultivo. Al igual que para determinar si los rizomas del lerén son los verdaderos sumideros o si actúan como un filtro/almacenamiento para la tuberización. Se llevaron a cabo varios experimentos de invernadero y de campo durante un periodo de dos años en la Estación de Campo de la Universidad de Trinidad Tobago. Los tratamientos evaluados fueron luz [luz solar completa y sombra (50%)], densidad poblacional (20.8 y 27.7 mil plantas por hectárea), y fertilización [N-P2-O5-K2O (13:13:20)]a varios niveles (0.0 a 0.6 t/ha). Se midió el área foliar, materia seca, y rendimiento de los tubérculos. Los resultados indicaron que el índice de área foliar varió entre 1.38 (luz solar) y 3.08 (sombra) y que el mismo no estuvo afectado por la nutrición del cultivo. Tanto para los ensayos de invernadero como los de campo, la acumulación de material seca en los rizomas y su distribución en los tubérculos fue mayor en los tratamientos con sombra que en aquellos bajo luz solar. La aplicación de fertilizantes no influenció el crecimiento de las hojas ni la producción de materia seca (capacidad fotosintética) en los ensayos en el invernadero, pero hubo mayor distribución de asimilatos desde los rizomas hasta los tubérculos cuando se usó una menor densidad poblacional x intercalado. La distribución de asimilatos de los tallos a los rizomas, y de los rizomas a los tubérculos fue más eficiente en los tratamientos de sombra x intercalado. La aplicación de fertilizante a la dosis de 0.5 t/ha a la densidad de 20.8 mil plantas por hectárea produjo la mayor cantidad de materia seca (1,066 g/planta) y el mayor rendimiento de tubérculos (261.3 g/planta). El estudio sugiere que en el lerén, los rizomas y tubérculos son los sumideros primarios y secundarios, respectivamente, con una distribución de asimilatos de tallos a rizomas y de rizomas a tubérculos.
Análisis filogenético de la roya americana de la soya, Phakopsora meibomiae.
Authors: Byron Vega  , Consuelo Estévez de Jensen
Published: May 2020

La roya americana de la soya (AmSR), causada por Phakopsora meibomiae (Arthur) Arthur, se encuentra limitada a pocas áreas del Hemisferio Occidental. No se conocen pérdidas severas causadas por este patógeno en cultivos de importancia económica. Phakopsora meibomiae infecta naturalmente 42 especies de leguminosas de la subfamilia Papilionoidea. Durante el 2008, se colectaron ocho aislados de AmSR infectando Lablab purpureus en la cordillera central de Puerto Rico. Se realizó análisis molecular filogenético de la región interna transcrita (ITS), incluyendo la región 5.8S ribosomal (rADN). La topología del árbol generado por los métodos de parsimonia y Neighbor-Joining fue similar. Los aislados se identificaron como Phakopsora meibomiae con un porcentaje de identidad entre el 98 y 100%. Estos aislados fueron agrupados en un grupo monofilético. Phakopsora pachyrhizi fue la especie más relacionada, y formó un segundo ciado. Otras especies de royas de los géneros Uromyces, Puccinia, Tranzschelia, Hemileia, el carbón Ustilago y la seta comestible Boletus se incluyeron en el análisis como grupos distantes. Las especies de Phakopsora agrupadas en la familia Pucciniaceae forman un ciado hermano con las familias Phakopsoraceae y Uropyxidaceae.
Alternaria spp. implicadas en el complejo de la enfermedad del tizón foliar de la cebolla en los trópicos.
Authors: Jessie Fernández  , Lydia I. Rivera-Vargas  , Irma Cabrera-Asencio  , Sharon A. Cantrell
Published: May 2020

Se colectaron aislados de Alternaria del follaje de cebolla en diferentes etapas del ciclo de vida de la planta. Se determinó la incidencia de las especies en los cultivares Excalibur y Mercedes durante dos épocas consecutivas de crecimiento en predios localizados en el sur de Puerto Rico. Se colectaron hojas al azar que mostraban lesiones elípticas hundidas de coloración púrpura a marrón con halos cloróticos. Se desinfestaron superficialmente cinco secciones (0.5 cm) de las hojas por cada muestra, se transfirieron a medio de cultivo, se incubaron y se documentaron los aislamientos. La incidencia de la enfermedad fluctuó de 25 a 52% en plantas de 60 a 100 días de madurez. Se observó un aumento en la incidencia de Alternaria en respuesta al aumento en la humedad relativa en los predios. En total se obtuvieron 280 aislados, de los cuales 35 se seleccionaron para la caracterización morfológica, patogénica y molecular. Un complejo de cinco especies diferentes de Alternaria está asociado a la quemazón o tizón de la hoja de cebolla en la isla. Se identificó a A. destruens, A. tenuissima, A. palandui, A. allii y un grupo de Alternaria sp. de esporas pequeñas perteneciente a un grupo taxonómicamente no descrito. Sesenta y dos por ciento de los aislados seleccionados pertenecen a este grupo, caracterizado por el patrón de esporulación intermedio de A. arborescens. Alternaria destruens y A. palandui no han sido reportadas anteriormente asociadas a cebolla en el Caribe ni en el Hemisferio Occidental. Las pruebas de patogenicidad mostraron que A. allii, A. tenuissima y Alternaria sp., fueron patogénicas al follaje de cebolla, siendo A. allii la más virulenta. Se utilizó la región ITS del rADN para la caracterización molecular de los aislados. Las relaciones filogenéticas basadas en las secuencias de la región ITS del rADN de los aislados de Alternaria y otras Pleosporaceae distinguen tres grupos o ciados. El primer ciado de aislados con esporas grandes y puntas filiformes incluye a A. allii, aislados durante este estudio, así como secuencias de aislados obtenidos del GenBank (A. porri, A. solani, A. macrospora, A. zinniae y A. sesamicola). Estas especies forman un grupo monofilético separado de otros miembros del género. El segundo ciado incluye un grupo diverso de Alternaria de esporas pequeñas: A. tenuissima, A. alternata, A. palandui, A. destruens y Alternaria sp.; y un tercer ciado que incluye a Stemphylium spp.
CLINODIPLOSIS CAPSICI (DIPTERA: CECIDOMYIIDAE): UNA NUEVA PLAGA PARA LOS AJÍES Y PIMIENTOS (CAPSICUM SP: SOLANACEA) EN PUERTO RICO
Authors: Irma Cabrera-Asencio  , Alberto Vélez
Published: May 2020

CLINODIPLOSIS CAPSICI (DIPTERA: CECIDOMYIIDAE): UNA NUEVA PLAGA PARA LOS AJÍES Y PIMIENTOS (CAPSICUM SP: SOLANACEA) EN PUERTO RICO
Toxicity of plant extracts for control of Trialeurodes vaporariorum W. (Homoptera: Aleyrodidae) in laboratory and greenhouse tomatoes.
Authors: Angeles-Martínez Octavio , García-Mateos Ma. Rosario , Rodríguez-Pérez Enrique , Sánchez-Alvarez Edna , Soto-Hernández Marcos
Published: May 2020

The constant search for natural insecticides in the form of extracts from many plants has received attention, and many of these extracts have been evaluated for their effectiveness as insecticides. To determine the toxic effect of six plant species Arundo donax L. (Poaceae), Brassica campestris L. (Brassicaceae), Cynodon dactylon L. (Poaceae), Hura polyandra Baill. (Euphorbiaceae), Phytollacca icosandra L. (Phytolaccaceae) and Sida acuta Burn. (Malvaceae) on Trialeurodes vaporariorum W. (Homoptera: Aleyrodidae) (adult whitefly), we evaluated the mortality rate and the lethal concentration (LC50) of the methanolic and aqueous extracts under laboratory and greenhouse conditions in a culture of Lycopersicum esculentum Mill. (Solanaceae). Analysis of Variance ANOVA and a test of comparison of means (Tukey, a = 0.05) showed a tendency of the methanolic extract in the six species towards a higher mortality rate and LC50 compared to that of the aqueous extract, both under greenhouse and laboratory conditions. The methanolic and aqueous extracts of A. donax and P. icosandra showed a higher toxicity under laboratory conditions (39.5 y 40.5%, respectively) than under greenhouse conditions (23.3 and 26.3%, respectively). The Treatments did not interfere with the tomato yield; so we are able to confirm the effectiveness of A. donax and P. icosandra extracts in the control of T. vaporariorum, which represents an ecological alternative for pest control in open field crops.
Planting season and date of harvest effect on biomass production and nitrogen contribution of Crotalaria juncea L. 'Tropic Sun' in southwestern
Authors: Santos Ana , Valencia Elide , Román-Paoli Elvin , Ramos-Santana Rafael
Published: May 2020

Sunn hemp (Crotalaria juncea L.) is a fast-growing, multipurpose legume of high N2 fixation ability, and an option for use in improving the fertility of degraded tropical soils. The objective of this study was to compare the effects of two planting seasons and three harvest dates on biomass yield (DMY) and N accumulation in the vegetative material of sunn hemp Tropic Sun'. Sunn hemp was seeded at the Lajas Agricultural Experimental Substation of the University of Puerto Rico in a Mollisol soil (San Antón Series) at a density of 7 kg/ha in May and October, and harvested at 84, 121, and 177 days after planting (DAP). The 177 DAP date proved to be not feasible because of previous senescence of the plants from the October planting; therefore, it was excluded from the analysis. Planting in May rather than October and harvesting at 121 DAP rather than 84 DAP resulted in higher DMY (kg/ha) (7,248 vs. 5,975 and 7,946 vs. 5,277, respectively). However, only the difference between planting seasons was significant (P < 0.05). The same tendencies were observed in N accumulation (kg/ha), means of 126.55 vs. 105.09 and 120.65 vs. 110.99, respectively, but without differences at P = 0.05. No interactions (P > 0.05) were detected between seasons of planting and date of harvest in these two dependent variables. Differences (P < 0.05) were found in N content of plant tissue, the upper canopy mean surpassing that of the lower canopy (2.12 vs. 1.00%). The highest crude protein content of 16.05% was found in the upper canopy for the May planting. These results suggest that sunn hemp has good potential as a cover crop and green manure in the Lajas region, and that summer planting is preferable.
Soil and interstitial water quality in Jobos Bay
Authors: Dumas José A. , Montalvo-Zapata Rafael
Published: May 2020

The Jobos Bay National Estuary Research Reserve (JBNERR) in Salinas, Puerto Rico, has served as sink for many anthropogenic substances that may affect the quality of the soil and water and the integrity of the biota. Four transects were established in the southeastern part of JBNERR for interstitial water collection. In addition, soil samples were collected from transects I, II, and III, at sites that were affected by runoff from a road closer to the Salinas landfill. The concentration of lead (Pb) in interstitial water from the above mentioned transects ranged from 0.07 to 0.68 mg/L: chromium (Cr) concentration ranged from 0.03 to 0.24 mg/L; and manganese (Mn) concentration ranged from 0.35 to 15.25 mg/L. The total Pb in soil samples ranged from 59 to 758 mg/kg, in an uneven distribution along transect II. The low Pb concentrations in water in comparison to that in soil indicate the high capacity of the JBNERR soils to serve as sink for heavy metals. The linear correlation between Pb concentrations in the interstitial water and the electrical conductivity suggests that marine water increases Pb remobilization from soils. Also detected in interstitial water were anthropogenic organic compounds such as benzothiazole, 1-methyl-2- pyrrolidinone and tert-butyl phenol; however, no residues of pesticides used from agricultural farms nearby were found. Results have shown that human activities have affected soil and water quality in the JBNERR.
Determinación de coeficientes genéticos en tres cultivares y un híbrido de maíz
Authors: Esteves Marilis , Román-Paoli Elvin , Beaver James S. , Muñoz Miguel A. , Armstrong Arístides
Published: May 2020

Se realizó un estudio en la Subestación Experimental Agrícola de Lajas de la Universidad de Puerto Rico para determinar el comportamiento agronómico de cuatro genotipos de maíz. El objetivo de esta investigación fue determinar los coeficientes genéticos de tres cultivares locales de maíz: 'Mayorbela' (M), 'Diente de Caballo' (DC), 'Chulo' (Ch) y de un híbrido transgénico de Pioneer Hi-Bred International, Inc. (híbrido Pioneer) para utilizarlos en el modelo CERES-Maize para predecir el comportamiento de estos genotipos bajo condiciones tropicales. Se determinaron los coeficientes genéticos para el crecimiento y desarrollo del maíz, los cuales incluyeron: duración de la fase juvenil del cultivo (P1), duración de la fase de acumulación de materia seca en el grano (P5), número potencial de granos por mazorca (G2), y crecimiento diario lineal del grano (G3). El crecimiento del cultivo se expresó utilizando el concepto de unidades termales (Td). Además, se estimaron otras variables de crecimiento tales como índice de área foliar y biomasa total acumulada. Se establecieron dos experimentos en el campo, en febrero 2004 y en marzo 2005. Los estimados de P1 durante el experimento del 2004 fueron 219 Td para el híbrido de Pioneer, y 253, 252 y 362 Td para M, DC y Ch, respectivamente. En el segundo experimento, realizado en el 2005, los valores estimados de P1 resultaron mayores a los obtenidos en el 2004; siendo de 352, 422, 479 y 405 Td para el híbrido Pioneer, M, DC y Ch, respectivamente. En el 2004 los valores de P5 fueron los esperados para todos los genotipos excepto para Ch. Estos valores corresponden a 715 Td para el híbrido Pioneer; 757 Td, 691 Td, y 413 Td, para M, DC y Ch, respectivamente. En el 2005, los estimados de P5 fueron mayores que en el 2004, especialmente para Ch, el cual casi se duplicó. En el 2004, el híbrido Pioneer obtuvo el mayor valor de G2, correspondiente a 616 granos por mazorca. No se detectaron diferencias significativas para G2 entre los genotipos estudiados; los valores de G2 variaron entre 529 y 616 granos por mazorca. En el caso de G3 los estimados fueron: 7.7, 6.7, 5.7 y 3.7 mg/día para el híbrido Pioneer, M, DC y Ch, respectivamente. Mientras, los valores estimados para G3 en el 2005 fueron 8.5, 6.9, 9.6 y 7.1 mg/día para el híbrido Pioneer, M, DC y Ch, respectivamente. No se encontraron diferencias significativas entre genotipos para índice de área foliar ni para biomasa acumulada. El rendimiento más alto en el 2004 lo obtuvo M con 4,148 kg/ha, seguido muy de cerca por el híbrido Pioneer, siendo esta diferencia no significativa. En el 2005 el híbrido Pioneer superó significativamente a M por 14%.