bluuebunny/crossref_metadata_2025 huggingface dataset:
Composición, abundancia y distribución de los sifonóforos (Cnidaria: Hydrozoa) en el Domo de Costa Rica, en febrero y marzo de 1979
Authors: Fernández-Álamo Ma. Ana , Ramírez-Arriaga Lidia
Published: March 2020

Introducción: El Domo de Costa Rica es considerado como uno de los lugares de mayor importancia debido a que es una zona de afloramiento de agua, donde se desarrolla una alta productividad primaria. Los sifonóforos son organismos depredadores que constituyen uno de los grupos más abundantes de la biomasa zooplanctónica. Objetivo: Analizar la composición específica, la abundancia y la distribución de los sifonóforos. Métodos: Las muestras fueron obtenidas durante la campaña oceanográfica DOMO I realizadas en febrero y marzo de 1979 por el personal del Laboratorio de Oceanografía Física del Instituto de Ciencias del Mar y Limnología de la Universidad Nacional Autónoma de México (UNAM). Las muestras de zooplancton fueron recolectadas con una red estándar tipo CalCoFI elaborada con malla de 0.3 mm y analizadas en el Laboratorio de Invertebrados de la Facultad de Ciencias de la UNAM. Resultados: Se identificaron un total de 30 especies de las cuales 27 pertenecen al suborden Calycophorae y tres al suborden Physonectae. Eudoxoides mitra, Muggiaea atlantica, Chelophyes contorta y Lensia hotspur fueron las especies dominantes; C. Contorta mostró una amplía distribución con 85% de aparición, seguida por Eudoxoides mitra (82%), Agalma okeni (73%), Muggiaea atlántica (64%) y Abylopsis eschscholtzi (61%). La fase poligástrica fue predominante en las especies de calicóforos y la fase eudoxia solo fue observada en Diphyes dispar, Eudoxoides mitra, Chelophyes appendiculata, Ceratocymba dentata, Abylopsis eschscholtzi, Abylopsis tetragona, Bassia bassensis y Enneagonum hyalinum. Conclusión: La alta diversidad y densidad de los sifonóforos en esta investigación muestra su importancia en la gran productividad del Domo de Costa Rica.
The sea anemone Exaiptasia diaphana (Actiniaria: Aiptasiidae) associated to rhodoliths at Isla del Coco National Park, Costa Rica
Authors: Acuña Fabián H. , Cortés Jorge , Garese Agustín , González-Muñoz Ricardo
Published: March 2020

Introducción: La diversidad de anémonas de mar en el Parque Nacional Isla del Coco, Costa Rica, está aún poco estudiada. Objetivo: Reportar por primera vez la presencia de la anémona de mar Exaiptasia diaphana. Métodos: Algunos rodolitos fueron examinados in situ en Punta Ulloa a 14 m. de profundidad mediante SCUBA durante la expedición UCR-UNA-COCO-I al Parque Nacional Isla del Coco el 24 de abril de 2010. Especímenes vivos fijados sobre rodolitos fueron fotografiados y sus medidas y carácterísticas morfológicas externas fueron registradas in situ. Resultados: Varios individuos de E. diaphana fueron observados sobre rodolitos y observamos repetidamente pequeños individuos rodeando a un individuo mayor (presumiblemente la anémona fundadora) sobre rodolitos de Punta Ulloa. Conclusiones: La distribución geográfica de esta especie es extendida, como así también su distribución batimétrica desde el intermareal hasta los 14 m de profundidad. Las imágenes obtenidas aportan evidencia de reproducción clonal por laceración pedal.
Historia Social de la Ciencia: “Moluscos de la Isla del Coco” (1935) de Paul Biolley
Authors: Díaz-Bolaños Ronald Eduardo
Published: March 2020

Introducción: El artículo “Moluscos de la Isla del Coco” publicado en la Revista del Colegio Superior de Señoritas (1935) es la traducción al español de una de las últimas obras de Paul Biolley Matthey (1862-1908), naturalista suizo radicado en Costa Rica, producto de una investigación malacológica efectuada en el marco de una expedición científica organizada por el Instituto Físico-Geográfico Nacional de Costa Rica (IFGN) en 1902, en una época en que el país reivindicaba su soberanía tanto en este territorio como en las zonas periféricas fronterizas. Objetivo: Analizar los aportes del artículo “Moluscos de la Isla del Coco” desde el enfoque de la Historia Social de la Ciencia. Métodos: La mayor parte de las investigaciones que han aplicado este enfoque en Costa Rica analizan procesos de institucionalización de disciplinas científicas. La metodología empleada en estos trabajos fue de gran utilidad para el análisis del artículo de Biolley, junto con la información de datos históricos proporcionados por otros textos sobre la Isla del Coco y el desarrollo de la investigación científica en Costa Rica desde una perspectiva temporal. Además, se hicieron tablas que sintetizan la clasificación de las especies y géneros estudiados por Biolley en la Isla del Coco para identificar su procedencia y el hábitat en el que viven. Resultados: Este estudio de Biolley constituye un texto de interés desde el punto de vista de la Historia Social de la Ciencia, debido a las descripciones que ofrece de las condiciones físicas del territorio de la Isla del Coco, de las diferentes especies de moluscos localizadas en ellas y al intercambio de información con científicos nacionales y extranjeros que evidencian la participación de Biolley en redes científicas. Conclusiones: Al analizar la información proporcionada por el artículo con los trabajos basados en el enfoque de la Historia Social de la Ciencia, se llegó a la conclusión que la recopilación de los datos de flora y de fauna permitió tener un mayor conocimiento de los recursos naturales de los territorios explorados, con el fin de colonizarlos e integrarlos a la dinámica económica del Valle Central de Costa Rica, sin embargo, los intentos para efectuar una colonización efectiva de la Isla del Coco fracasaron dada la distancia entre esta y el continente, además de las condiciones topográficas que impiden el establecimiento permanente de poblaciones humanas y sus actividades productivas.
Prevalence and risk factors to Demodex folliculorum infection in eyelash follicles from a university population of Mexico
Authors: Vargas-Arzola Jaime , Segura-Salvador Aristeo , Torres-Aguilar Honorio , Urbina-Mata Mario , Aguilar-Ruiz Sergio , Díaz-Chiguer D. Lucía , Márquez-Navarro Adrián , Morales-Reyes Lázaro , Alvarado-Vásquez Noé , Nogueda-Torres Benjamín
Published: March 2020

Demodex folliculorum shows a high occurrence in the general population, however, its pathologic relevance is still controversial. In this prospective study, we evaluated the prevalence of D. folliculorum on eyelashes from 8,033 subjects of a university population (including 7,782 students, and 251 academics). Additional information on some risk factors to infection by the mites was evaluated, as well. A prevalence of 1.47% was found, where 118 individuals were positive for D. folliculorum; and, among them, 63 (53.4%) were women and 55 (46.6%) were men. Results showed a negative correlation with the age (r = −0.45), the highest prevalence was found in individuals between 19 and 22 years of age (2.1%, 84 patients). The number of D. folliculorum mites did not differ between the right and left eye; however, the use of cosmetics or facial cream, contact lens, hair removers, were factors present in patients infected with D. folliculorum. Although Demodex prevalence did not increase in line with weight, we found significantly higher prevalence in the 51–60 kg and 71–80 kg weight groups, and a particularly high prevalence in the over 81 kg weight group (2.6%). In conclusion, it was observed that the main population positive to infection consisted of young adults; this is in contrast with the international evidence reporting a high rate of infection in older adults. Besides, our results suggest that items of daily use such as cosmetics, facial cream, eyeliner, glasses, or contact lenses may be some of the main culprits of the infection by D. folliculorum.
Fatal case of bacteremia caused by Streptococcus suis in a splenectomized man and a review of the European literature
Authors: Ágoston Zsuzsanna , Terhes Gabriella , Hannauer Péter , Gajdács Márió , Urbán Edit
Published: March 2020

Streptococcus suis is an emerging zoonotic human pathogen, which is a causative agent of invasive infections in people who are in close contact with infected pigs or contaminated pork products. It is associated with severe systemic infections, most commonly meningitis and sepsis, which may lead to high rates of morbidity and mortality. Serotype 2 is the most prevalent type in S. suis infections in humans. We have reported a case of a very rapidly proceeding fatal human S. suis infection in a splenectomized, but otherwise immunocompetent patient in Hungary. We would like to highlight the attention for this pathogen for the risk group patients, not only pig breeders, veterinarians, abattoir workers, meat processing and transport workers, butchers and cooks, that those persons who are immunocompromised including those with spleen removed, persons with diabetes mellitus, cancer and alcoholism, are also at greater risk of infection.
The southernmost distribution of the Rhinoceros Snake, Gonyosoma boulengeri (Mocquard, 1897) (Reptile, Squamata, Colubridae), in Vietnam
Authors: Nguyen Luan Thanh , Kane Daniel , Le Manh Van , Nguyen Thang Tai , Hoang Ha Van , Mccormack Timothy E. M. , Tapley Benjamin , Nguyen Sang Ngoc
Published: March 2020

We report the southernmost record of the Rhinoceros Snake, Gonyosoma boulengeri (Mocquard, 1897) from Phu Yen Province, southern Vietnam, based on a single specimen collected from forest in the Ca Range. This record extends the distribution of G. boulengeri approximately 600 km south of previous records in Vietnam (Quang Binh Province, central Vietnam). A detailed description of a hemipenis is also provided for the first time.
First record of the termite, Dentispicotermes cupiporanga Bandeira & Cancello, 1992 (Isoptera, Termitidae, Termitinae) from Venezuela and new genus records from Bolivia and Paraguay
Authors: Issa Solange , Scheffrahn Rudolf H.
Published: March 2020

Dentispicotermes Emerson, 1950 comprises five species confined to the Neotropics. We report the presence of D. cupiporanga Bandeira & Cancello, 1992 in northern Venezuela and two undescribed congeners from Bolivia and Paraguay. This soil-feeding termite genus is rare and is characterized by a diagnostic enteric valve armature that we describe for the first time.
Adorno e a mutação do conceito de ideologia
Authors: Ribeiro Felipe
Published: March 2020

O artigo busca explicitar o diagnóstico elaborado por Adorno no período pós-guerra, segundo o qual o conceito tradicional de ideologia teria perdido seu objeto no mundo totalmente administrado. Se nos termos marxistas tradicionais a ideologia funcionava a um só tempo como falsa consciência e promessa não cumprida, enquanto que o desencadeamento das forças produtivas, por sua vez, era tomado como a mola material para a realização dos conteúdos normativos contidos na ideologia burguesa, então o diagnóstico de Adorno segundo o qual no capitalismo tardio as relações de produção assumem certa primazia diante das forças produtivas vem para abortar a vigência dessa noção tradicional de ideologia. No mundo administrado, a ideologia não estaria mais nas objetivações espirituais que operam como um véu sobre as relações materiais, mas, nos termos de Adorno, seria o próprio “rosto assustador do mundo”, o que faz ideologia e realidade “correrem uma em direção à outra”. Tudo se passa como se a atual consciência do capitalismo contemporâneo não mais legitimasse seus processos por meio de sua escamoteação ideológica, mas enunciasse seu próprio fundamento econômico com força apologética, fazendo da realidade sua própria ideologia. Neste texto, buscaremos reconstruir essa ideia com mais detalhe.
Disciplina e teoria - Uma reflexão sobre a formação partindo da filosofia kantiana*
Authors: Farhat Pedro Casalotti
Published: March 2020

A intenção deste texto é articular dois temas pouco trabalhados juntos nas interpretações de Kant, embora sejam, segundo nosso entendimento, de fundamental importância para uma plena compreensão da filosofia kantiana e do conhecimento filosófico em geral: a disciplina da razão pura e a filosofia teórica. Pretendemos nos utilizar de algumas outras noções, no entanto, para responder a seguinte pergunta: é possível a formação sem a disciplina filosófica? Isto é, seria possível uma formação teórica (principalmente do conhecimento, mas também do indivíduo) sem uma disciplina ou uma “contribuição negativa” proveniente da filosofia? O conceito de formação está, segundo gostaríamos de defender, de um ponto de vista teórico, associado intrinsecamente à disciplina da razão. Assim, indicando como esta é, em geral, relacionada, nas interpretações de Kant, apenas com a pedagogia e com a filosofia prática, gostaríamos de, indo no sentido contrário, tratar do lugar da disciplina da razão em relação ao conceito de formação em seu sentido teórico, isto é, de fundamentação do conhecimento. A disciplina da razão pura revela-se, portanto, uma condição necessária para o filosofar e para a formação do conhecimento em geral.
Edgar Morin e o pensamento complexo: uma possibilidade cognitiva
Authors: Rocha Junior Ruy
Published: March 2020

Este artigo tem como pretensão apresentar alguns elementos teóricos da teoria da complexidade presente em Edgar Morin. A proposta segue por um viés de aproximar o leitor da compreensão de complexidade e completude; a polidisciplinaridade e a transdiciplinaridade com vista em destacar como a abordagem de Morin almeja despertar o conhecimento que, segundo o autor, esta adormedico.
A contribuição do Gnothi Seauton para a educação
Authors: Merlin Barbara Marques
Published: March 2020

O presente texto tem como objetivo adjuntar à máxima délfica gnothi seauton (conhece-te a ti mesmo) como auxílio para a educação contemporânea. Este preceito foi apresentado por Michel Foucault (2018) em um de seus cursos no Collège de France no ano de 1981-1982 intitulado como A hermenêutica do sujeito. Foucault utilizará como eixo de seu curso o diálogo socrático O primeiro Alcibíades (2016) para demonstrar a relação entre mestre e discípulo em uma ótica do cuidado de si.A educação nos dias atuais tem passado por momentos de incertezas, das quais professores e alunos se distanciam cada vez mais, este distanciamento por incrível que pareça, interfere no desenvolvimento dos alunos em sala de aula, sobretudo no ensino médio em que os adolescentes estão em momento de reconhecimento e busca pela própria identidade, a proposta é trazer este preceito para a contemporaneidade afim de reaproximar professores de alunos.O conhece-te a ti mesmo será, portanto, o fio condutor para encontrar o caminho dessa aproximação entre ambos, será por esta relação do cuidado de si que o reencontro consigo mesmo será possível dentro e fora da sala de aula. Para que isso seja possível, percorreremos tais caminhos; (i) entender o conceito de gnothi seauton e (ii) o cuidado de si como estratégia para a educação nos dias atuais.
Incidências e incidentes: uma análise das coberturas das mortes de policiais e moradores de favelas
Authors: Pereira Pedro Barreto
Published: March 2020

Este trabalho tem como objetivo analisar comparativamente a cobertura jornalística de O Globo sobre as mortes de policiais militares e moradores de favelas, e as suas consequências. Os casos analisados são o do capitão Uanderson da Silva, comandante da UPP Nova Brasília, em setembro de 2014, e o do menino Eduardo de Jesus, de 10 anos, em abril de 2015. As circunstâncias em que ambas as mortes se deram e o tratamento, tanto da mídia, como da Justiça, são reveladoras. Utilizando os conceitos de “incidências” e “incidentes” (COMAROFF E COMAROFF, 2006), é possível colocar em relevo diferentes situações, apontar como elas são reportadas e ainda qual a relação entre este discurso e as políticas públicas governamentais de Segurança Pública vigentes.
Entrepreneurial attitude and success in the Colombian auto parts sector
Authors: Prada Ricardo
Published: March 2020

The growth, transformation and development of new economic sectors of a country can be determined from the entrepreneurship. This entrepreneurial attitude manifests itself from different approaches, not only by the emergence of new companies, but also by decision-making and entrepreneurial activity, in certain situations. Business success can be attributed to the different influences, changes and pressures caused by the environment, or to special characteristics of entrepreneurs, personal aspects and environment. This article aims to analyze intra-entrepreneurship as a business renewal strategy, exploring the auto parts sector, through a qualitative study in a sample of companies in the auto parts sector in Colombia. The results conclude that despite the fact that intra-entrepreneurship is considered a strategic scenario for business renewal, Colombian auto parts companies do not promote their strategic development.
Internationalization process of Spanish firms of the service sector
Authors: Araya-Castillo Luis , Mendoza Xavier
Published: March 2020

The objective of this research is responding to two important questions that have been analyzed in the literature on international management, the “where” and the “how”. With this purpose both descriptive and comparison of means analysis are applied. The resulting analysis indicates that Spanish multinationals in the service sector have a semi global focus in their international operations and are located principally in Europe and Latin America. Furthermore, we found that Spanish service multinationals exert high levels of subsidiary control and that do not present significant differences in the levels of control they have over subsidiaries in relation to the type of service.
Variables y parámetros del modelo Kano aplicado al turismo de salud.
Authors: Contento  Sepulveda Michael Steven , Saenz Blanco Fabiola , Bautista Mendoza Juana Mayerly
Published: March 2020

El sector de turismo en salud en Colombia ha venido incrementando su reconocimiento a nivel internacional, principalmente por factores determinantes de calidad y costos, es así como se convierte en un factor significativo para la economía medido a través del PIB. En esta perspectiva, el modelo Kano puede permitir la identificación de las necesidades y requerimientos de los usuarios, con la finalidad de mejorar los estándares y coberturas ofrecidos actualmente por dicho sector.
Student learning about UK health services in a cross-border curriculum partnership; the London-Cyprus experience
Authors: Baig Shehla , Nicolaou Stella A. , Lawrence Denise , Myers Janette , Begum Mursheda
Published: March 2020

This article was migrated. The article was marked as recommended. Purpose of the articleCross border partnerships require curricula, faculty and students to negotiate challenges associated with national regulatory frameworks, contexts and cultures. This study investigated student attitude and behaviours when encountering learning about health services in host and home students in the context of problem based learning.Materials and MethodsFirst year graduate entry students' health systems interest and exposure and their perceptions of the dynamics of learning in PBL were investigated via a questionnaire comprising open and closed questions. Results and ConclusionsResults showed a difference between home and host students in the ways they learned about home health systems and their attitudes to the value of learning about home and international health systems. There was no difference in the quantity of health service related learning objectives generated. Both groups reported noticing differences between the PBL cases and clinical practice, however, perceptions of the reasons for the differences varied between home and host students. We are interested in the way in which this perception of difference was reported as either a stimulus or a barrier to learning.
Caracterización sociodemográfica y psicológica de los casos de suicidio y una serie de casos de intento suicida en Popayán en el año 2007
Authors: Charry Lozano Liliana
Published: March 2020

Antecedentes: Se determinaron las características sociodemográficas y psicosociales de los suicidas y parte de la población que intentó suicidarse en la ciudad de Popayán en el año 2007. La incidencia de suicidio en Colombia ha venido incrementándose desde 1985 cuando era de 3,5 por 100.000 habitantes al año, hasta 1999 que era de 5 por 100.000 habitantes al año. Posteriormente se ha sostenido relativamente estable, en el 2007 la mortalidad por suicidio en Colombia fue de 4.1 por 100.000 habitantes1. En Popayán las tasas por 100.000 habitantes en los últimos cuatro años fueron 15,1, 9,8, 15,6 y 9,8 respectivamente siendo mas altas que las del Departamento del Cauca 4.52. OBJETIVO: Describir el fenómeno del suicidio en la ciudad de Popayán en el año 2007 considerando las dimensiones sociodemográfica y psicológica de los suicidios e intentos suicidas. MÉTODOS: Se realizó un estudio descriptivo comparativo en el cual se tomaron 122 sujetos que intentaron suicidarse y que consultaron al hospital Susana López de Valencia y el total de suicidas de la ciudad de Popayán en el año 2007. La información en el caso de los suicidas fue tomada del certificado de defunción, acta de levantamiento y acta de entrega del cadáver y de un instrumento vigente en el Instituto de Medicina Legal y Ciencias Forenses de la ciudad donde se realiza la necropsia médico legal; el mismo instrumento se utilizó para obtener la información en el caso de intentos suicidas mediante la revisión de historias clínicas de los pacientes que intentaron suicidarse y fueron atendidos en el hospital Susana López de Valencia. El análisis de los datos recolectados se realizó con el paquete estadístico STATA V.10. RESULTADOS: se pudo evidenciar el perfil de los sujetos que se intentaron suicidar, para la ciudad de Popayán: ser mujer, joven procedente de área urbana, con bajo grado de escolaridad, con relación familiar estable, con conflicto en la familia, sin antecedente de enfermedad mental y que utiliza como método la intoxicación. Para el suicidio se definió: ser hombre, joven procedente de área urbana con mayor grado de escolaridad, con relación marital inestable, con conflicto de pareja o económicos y que utiliza como método el ahorcamiento.
Rare Disaster Probability and Options-Pricing
Authors: Barro Robert J. , Liao Gordon Y.
Published: March 2020

We derive an option-pricing formula from recursive preferences and estimate rare disaster probability. The new options-pricing formula applies to far-out-of-the money put options on the stock market when disaster risk dominates, the size distribution of disasters follows a power law, and the economy has a representative agent with a constant-relative-risk-aversion utility function. The formula conforms with options data on the S&P 500 index from 1983-2018 and for analogous indices for other countries. The disaster probability, inferred from monthly fixed effects, is highly correlated across countries, peaks during the 2008-2009 financial crisis, and forecasts rates of economic growth.
PORTFÖY OPTİMİZASYONUNDA VERİ SETLERİNİN VE OPTİMİZASYON SEÇENEKLERİNİN KARŞILAŞTIRILMASI: BİST-30 ENDEKSİ ÜZERİNE BİR UYGULAMA
Authors: URUN Kutlay , TAŞ Oktay , UĞURLU Umut
Published: March 2020

Bu çalışmada Türkiye’deki BİST-30 endeksinde yer alan hisselerin
01/07/2015 – 31/12/2015, 01/01/2015 – 31/12/2015, 01/01/2014 – 31/12/2015 ve
01/01/2013 – 31/12/2015 tarihleri arasındaki günlük getirilerine, Geleneksel
Portföy Yöntemi temel alınarak eşit ağırlıklandırma; Modern Portföy Teorisi
temel alınarak risk kısıtlı getiri maksimizasyonu, getiri kısıtlı risk
minimizasyonu, direkt risk minimizasyonu ve Sharpe oranı maksimizasyonu
uygulanmaktadır. Birinci durumda, yatırımcının amaç fonksiyonuna göre hangi
optimizasyon seçeneğinin kullanılması gerektiği, ikinci durumda ise yatırımcı
tipine göre hangi veri setinin kullanılması gerektiği incelenmiştir. Son olarak
Modern Portföy Teorisi temel alınarak oluşturulan dört farklı optimizasyon
seçeneğinden bazılarının Geleneksel Portföy Yönetimi temel alınarak eşit
ağırlıklandırma yapılmış portföyden daha iyi sonuç vermediği gözlemlenmektedir.
EFFICIENCYAND PERFORMANCE MEASUREMENT OF TURKISH UNIVERSITIES VIA DATA ENVELOPMENT ANALYSIS
Authors: SOUMMAKİE Bushra , TALAY İsilay
Published: March 2020

The
number of Turkish universities taking place in the global university rankings
has been increasing. Hence, it is necessary to develop a mechanism to measure
their efficiency. In this study, performance and efficiency measurement of
universities in Turkey was conducted via data envelopment analysis (DEA), and
the activities included in the performance definition were research indicators
and internet and website focused indicators. The analysis was performed for 50
universities in Turkey. It has been observed that some universities which are
successful in terms of research activities have not achieved similar success in
the interest and traffic to their websites. In the study, suggestions for
improvement in this and similar performance and efficiency metrics were
presented.
Technological possibilities of using natural gas in shaft furnaces for limestone roasting
Authors: Matyukhin V. I. , Yaroshenko Yu. G. , Zhuravlev S. Ya. , Morozova E. V. , Matyukhina A. V.
Published: March 2020

One of the ways to improve the technology of limestone roasting in shaft furnaces is associated with improvement of conditions of combustion with natural gas when burning it directly in the layer. To implement this technology, it is necessary to ensure the development of two parallel processes: preparatory, in which the initial gas-air mixture is formed and heated to the ignition temperature, and the main one, during which a layer of combustion of gaseous fuel occurs. At air-blast tuyere feed and at coaxial jet supply of gaseous fuel under increased pressure when there are gas permeable nozzles in the path, a more powerful gas flow (natural gas) flows out of the nozzle at high speed into the external environment. It creates conditions for air flow ejection. Inside the annular space between the streams, a combustion zone is formed, on the inner and outer side of which there are circulating vortices directed along the axis of the jet to the nozzle. It improves stability of the gas-air mixture ignition. The considerable range of turbulent jets (at elevated pressures of the gaseous medium), as well as the possibility of sufficient complete mixing in the boundary layer, opens up the possibility of forming a gas-air mixture of a given composition along the front of the flare process, the movement of gas jets. To ignite the gas flow in the layer, it is necessary to ensure its preheating at least to a temperature of 800 – 1050 °C using a heat source located near its entrance. Energy efficiency of this direction is confirmed by experimental studies on a shaft furnace with a working space with diameter of 3 m. According to the results of experimental sounding of the heated zone of a limestone shaft furnace (in the mode of layer burning of natural gas), regularities were established in changing the temperature field of the burning layer with the formation of maximum temperature of 1200 °C at a distance of 200 mm from the nozzle section. The depth of formation of the combustion zone was limited to the level of 110 mm with the spread of the region of high temperatures over a distance of up to 1000 mm. Technological possibility of forming a region of high temperatures of 1100 – 1600 °C with a length of the high-temperature zone up to 2000 mm was established.
Additional shearing impact on the effectiveness of MSR technology in conditions of billet CCM
Authors: Smirnov E. N. , Sklyar V. A. , Bogadevich D. I. , Smirnov A. N. , Belevitin V. A.
Published: March 2020

Aside from electromagnetic stirring, casting with low superheat and intensive cooling of the strand in the upper range of secondary cooling zone, Mechanical Soft Reduction (MSR) has proved, above all, to be very effective in reducing segregation and axial porosity in continuously cast billet. Implementation of MSR technology in the production of continuously cast billets has a number of features that are due to their square shape. In this case, particularly promising is the use of blocks of segment design, so called pinch-roll segment. The presence in CCM line of MSR block of such design allows to implement a two-stage deformation scheme. The paper proposes a new two-stage scheme of MSR technology realizing the combined deformation on the basis of cobbing in vertical plane and shearing relative displacement of the faces at the first stage, and at the second stage – deformation on the basis of cobbing in vertical plane. This approach additionally helps to correct deformations of the profile cross section, namely the rhomboidity defect. We present the results of a comparative study using physical modeling methods to assess the contribution of additional shear relative displacement of faces in the horizontal plane to the overall efficiency of MSR technology of continuous casting. The use of a flat model in conjunction with the proposed form of deforming rolls and a combination of modeling materials allowed to achieve a good similarity in geometric criterion, as well as in the criterion of stress ratio equivalence arising at the interface of crystallization front. The obtained experimental data helps to develop ideas about the mechanisms of additional positive effect from the application of shear action. In particular, the deformation of metal surface and adjacent layers of the billet in the rolls with a special above-described profiling will improve their quality due to the occurrence of shear deformations intensifying the process of collapse of subcortical bubbles, “healing” of microcracks, etc. In turn, the artificial creation of torque effect in cross section of the billet will contribute to the occurrence of shear deformations in the crystallized “bridges” of axial liquid-solid region of the ingot, thereby intensifying the process of their destruction and improving the quality of the billet’s macrostructure.
Dynamics of electromagnetic forces rejecting arcs from verticals in a three-phase arc furnace
Authors: Yachikov I. M. , Kostyleva E. M. , Portnova I. V.
Published: March 2020

Knowledge of the nature and behavior of forces acting on an arc is important when designing furnaces, controlling and automating their work. The effect of electromagnetic arc blowing has a negative effect on technical and economic indicators of the furnace, since the arc is removed from dimples in metal and slag. Radiation of the arc on walls and arch increases. And the effective power absorbed by the metal decreases. For this and a number of other tasks, it is necessary to know the dynamic behavior of the arc, which is largely determined by the instantaneous values and directions of the individual forces and the resultant force. The paper discusses the behavior of an electromagnetic force acting on an arc column from currents flowing through a liquid metal and currents flowing through other parallel arcs and graphitized electrodes in a three-phase AC arc furnace. It was assumed that the arcs burn perpendicular to the surface of the metal bath (their axes coincide with the axes of the electrodes) and effective value of the linear currents in different phases is the same. A mathematical model is proposed for calculating the instantaneous values and directions of the main electromagnetic forces acting on arcs in a three-phase arc furnace, allowing to reveal the nature of arcs dynamic behavior. A computer program has been created that makes it possible to visualize the behavior of a hodograph of forces acting on an arc. Hodographs of forces acting on the arc from the currents flowing through the melt are shown; they are ellipses lying in a horizontal plane. The resulting force deflecting an arc is also an even harmonic function with a frequency twice as high as the industrial frequency of the current. Its hodograph is an ellipse lying in a horizontal plane, the big semi-axis of which makes an angle of 20 – 80° with a line connecting the center of decay of the electrodes and the electrode axis.
Smyslova Simulation modeling of logistic system for liquid iron transportation at metallurgical plant
Authors: Vinogradov K. O. , Smyslova A. L.
Published: March 2020

During the study of technological data of the process of liquid iron transportation, it was found that the number of locomotives and mixers depending on the duration of operations and especially on the inter-operational downtime does not always ensure normal rhythm of the main production. It leads to significant production losses, therefore, the work of the producing and transport complex is not effective enough. The authors have developed a simulation model of a logistics system for transporting liquid iron at a metallurgical plant. The study and construction of the model was performed using AnyLogic. Real data from production, namely the schedule of blast furnace smelting for a three-week period, was used as the initial data. To prove adequacy of the model, the results were compared with the actual tact of the mixers movement, as well as with the theoretical need of the converter shop. Values of the liquid iron weight delivered to the converter shop were obtained during the simulation and were related to the theoretical ones. Efficiency of the model is achieved by automatically collecting in real time of statistical values of the parameters of simulation objects. The system analyzes the collected data and makes decisions based on them for a short period of time (less than one second). In default operation mode of the simulation model, motion of the mixers is controlled automatically without participation of the dispatcher, which improves efficiency, as well as decision-making speed. Such model provides simulation of failures in operation of the converter shop. According to the simulation results, it can be concluded that the system delivers less liquid iron to a converter shop, but retains its rhythm. After resuming the operation of all converters, the tact of transportation reaches the required level.
Neural network approach to forecasting the cost of ferroalloy products
Authors: Sirotin D. V.
Published: March 2020

The article notes the increasing role of ferroalloy sub-sector in the qualitative development of metallurgy. Progress predicts of modern metallurgy are difficult in the context of increasing risks of global economic development. The high volatility of domestic producers’ prices for the main ferroalloys also has a negative impact. It is necessary to develop methodological tools for forecasting changes in market prices for metallurgical products with a high degree of accuracy. One of the important areas of application in metallurgy forecasting tools is construction of a model for forecasting the cost of ferroalloy products. It is the main purpose of the study. On the example of constructing a forecast model for changing the price of ferrosilicon, relevance of the neural network approach to forecasting the cost of ferroalloy products was substantiated. As part of the tasks of industry development, the capabilities of neural networks have been poorly studied to date. Formal description of the time series forecasting model based on neural networks is given. When constructing neural networks, any time series problem is represented as a multidimensional regression problem. The main parameters of predictive networks training are highlighted. The average price of ferrosilicon on the Russian market and the prices in the Russian regions were used as input variables. The networks that meet the qualitative criteria of forecasting models were trained. Selection of the networks was carried out taking into account the results of graphical analysis and cross-checking. A neural network model was constructed to predict the change in ferrosilicon price in the short term with high accuracy. This model can be useful in strategic decisions justifying in the activities of industry research institutes and metallurgical enterprises.
Chemical reactions at reduction of iron from oxides by natural gas
Authors: Berdnikov V. I. , Gudim Yu. A.
Published: March 2020

The main component of natural gas is methane CH4 , that is, a component consisting of two active reducing agents for iron – carbon and hydrogen. Previously, computer simulations have found that the reduction of iron from magnetite with carbon begins at 680 °C, and its reduction with hydrogen – at 350 °C. In this paper it is shown that the beginning of the reduction of iron with methane should be expected at a temperature of 530 °C. However, this temperature for natural gas, obtained from gas condensate fields and containing up to 10 % of heavy hydrocarbons and impurities, increases to 550 °C. When using natural gas together with oxygen in the ratio CH4 : O2 = 2:1, temperature of the beginning of reduction also increases to 620 °C. In addition, a calculation formula was proposed for Fe – O – C – H system, which allows predicting the formation of a “pure” phase of iron at 1500 °C based on the chemical composition of the reducing gas mixture.
To the 60th Anniversary of Oleg Yur’evich Sheshukov
Authors: Editorial Article
Published: March 2020

.
The transport and fate of marine plastics in South Africa and adjacent oceans
Authors: Ryan Peter G.
Published: March 2020

South Africa is thought to be one of the worst contributors of plastic into the sea globally. Although some plastic items derive from offshore sources (mainly fishing and other maritime activities, but also long-distance transport), the importance of local, land-based sources is indicated by the composition of beach debris and the concentration of macro-, meso- and microplastics close to urban source areas. Some 60–90% of plastic from land-based sources is expected to strand on beaches, but plastic standing stocks on beaches are much lower than global model predictions of land-based pollution. Burial in beaches and transport into backshore vegetation are significant sinks, although this plastic is likely to be released as the climate crisis leads to rising sea levels and more extreme storms. Most buried items are fairly small, while many larger items, which account for most of the mass of plastic, are removed from beaches by cleaning efforts. However, even daily accumulation rate estimates – which exclude the effects of cleaning – fall well short of model predictions of plastic leakage from land-based sources. Oceanographic models predict that plastics entering the sea from South Africa are exported to the South Atlantic and Indian Oceans, with the proportion depending on source location and item density. At sea, floating macroplastic is concentrated close to urban centres. Farther offshore, plastic items tend to be large and buoyant because biofouling causes small, low buoyancy items to sink. Size-selective removal of plastics by biota might also contribute to the paucity of floating microplastics (<1 mm). The seabed is likely to be the main long-term sink for waste plastics, but the limited data available indicate low levels of plastics on the seabed off South Africa. Only a small proportion of plastic predicted to leak into the sea from South Africa can be accounted for. However, this should not delay the implementation of effective mitigation measures to limit plastic leakage.
Significance:

High densities of waste plastic around urban centres indicate that most macro- and microplastics come from local, land-based sources and do not disperse far at sea.
Beach clean-ups remove up to 90% of the mass of stranded plastic, largely found in macroplastic items (>25 mm).
The seabed is a long-term sink for marine plastics, but densities of plastic on the seabed around South Africa are still modest.
The global model prediction of plastic leakage from South Africa into the sea probably is a gross overestimate.
Monitoring marine plastics – will we know if we are making a difference?
Authors: Ryan Peter G. , Pichegru Lorien , Perold Vonica , Moloney Coleen L.
Published: March 2020

In the context of marine anthropogenic debris management, monitoring is essential to assess whether mitigation measures to reduce the amounts of waste plastic entering the environment are being effective. In South Africa, baselines against which changes can be assessed include data from the 1970s to the 1990s on microplastics floating at sea, on macro- and microplastic beach debris, and interactions with biota. However, detecting changes in the abundance of microplastics at sea is complicated by high spatial and temporal heterogeneity in net samples. Beach debris data are easier to gather, but their interpretation is complicated by the dynamic nature of debris fluxes on beaches and the increase in beach cleaning effort over time. Sampling plastic ingested by biota is a powerful approach, because animals that retain ingested plastic for protracted periods integrate plastics over space and time, but there are ethical issues to using biota as bioindicators, particularly for species that require destructive sampling (e.g. turtles, seabirds). Bioindicators could be established among fish and invertebrates, but there are technical challenges with sampling microplastics smaller than 1 mm. Fine-scale debris accumulation on beaches provides an index of macroplastic abundance in coastal waters, and offers a practical way to track changes in the amounts and composition of debris in coastal waters. However, upstream flux measures (i.e. in catchments, rivers and storm-water run-off) provide a more direct assessment of mitigation measures for land-based sources. Similarly, monitoring refuse returned to port by vessels is the best way to ensure compliance with legislation prohibiting the dumping of plastics at sea.
Significance:

Monitoring is required to assess whether mitigation measures to reduce waste plastics at sea are making a difference.
Monitoring the leakage of plastic from land-based sources is best addressed on land (e.g. in storm drains and river run-off) before the plastic reaches the sea.
Illegal dumping from ships is best addressed by monitoring the use of port waste reception facilities.
Sampling plastic ingested by biota is a powerful approach, using fish and invertebrates as bioindicators for larger microplastic fragments.
Señalización y el éxito de las campañas de crowdfunding latinoamericano
Authors: Tonon Ordóñez Luis B. , Sánchez Fontana Walter M.
Published: March 2020

Las oportunidades de financiamiento para emprendimientos en Latinoamérica son pocas, limitándose comúnmente al uso de instituciones tradicional como la banca pública y privada, o incluso a recursos recaudados informalmente, ninguno de estos particularmente estructurado para emprendimientos de etapa temprana. A esto, han surgido nuevos mecanismos de recaudación como el Crowdfunding basado en recompensa. Sin embargo, este sufre en Latinoamérica de grandes porcentajes de fracaso y un crecimiento general desacelerado en comparación a otras regiones. Esta investigación empírica, pretende contribuir al entendimiento de los factores que hacen a una campaña exitosa desde la perspectiva de la teoría de señalización. Basado en la información recaudada de 21804 campañas de origen latinoamericano, extraídas de ocho países distintos, de las plataformas Catarse, Kickstarter e Idea.me; Los resultados indican que el uso de redes sociales, número de recompensas, material multimedia incluyendo imágenes, videos y gifs, así como esfuerzos para comunicarse con el cliente sea durante o después de culminado el plazo de recaudación, influyen positivamente al éxito de una campaña. Se determina también un uso marginal de todas estas señales, independientemente del país de origen de las campañas o su naturaleza. El mermado crecimiento de la escena de Crowdfunding en la región se entiende, está siquiera en parte afectada por la calidad inherente de los proyectos, donde hay mucho espacio por mejorar en referencia a las señales usadas.
Идентификация и определение биологически активных веществ шалфея лекарственного Salvia officinalis L., полученных в условиях субкритической экстракции
Authors: Рябоконь Лилия Петровна , Милевская Виктория Васильевна , Киселева Наталия Владимировна , Темердашев Зауаль Ахлоович
Published: March 2020

Объектами исследования были листья шалфея лекарственного (Salvia officinalis L.) из серии«Зеленая аптека», г. Горячий Ключ, Травы Кавказа. Работа посвящена изучению возможности использования альтернативного способа извлечения, идентификации и определения биологически активных веществ из лекарственных трав под воздействием субкритической экстракции. Целью исследований является компонентный состав биологически активных веществ шалфея лекарственного, образующийся в условиях субкритической экстракции. Субкритическая экстракция биологически активных веществ из шалфея лекарственного (Salvia officinalis L.) проводилась с использованием деионизированной воды и 70% раствора этилового спирта в температурном диапазоне от 100 до 250°С. Хроматографическое определение аналитов в экстракте шалфея лекарственного проводили методом газовой и жидкостной хромато-масс-спектрометрии в сочетании с техникой твердофазного концентрирования. Идентификацию аналитов осуществляли с  использованием стандартных образцов и индивидуальных соединений. Проведена оптимизация условий субкритической и твердофазной экстракции компонентов эфирных масел и фенольных соединений из экстракта шалфея лекарственного. Оптимальный выход эфирномасличных компонентов из шалфея лекарственного достигается при 200оС, дальнейшее повышение температуры приводит к деградации исследуемых соединений и снижению эффективности их извлечения. Аналиты переводили в органическую фазу твердофазной экстракцией с использованием сорбентов «Strata C18-E», «Strata X», «Oasis HLB». Эфирномасличные и фенольные компоненты в органической фазе получены при субкритической экстракции в условиях повышенных температуры и давлении. Идентифицированный компонентный состав экстракта, образующийся в условиях субкритической экстракции, существенно отличается от веществ, полученных традиционным гидродистилляционным способом. В составе шалфея лекарственного идентифицированы 52 эфирномасличных соединения. Субкритическая экстракция позволила в отличие от гидродистилляционного способа одновременно извлекать компоненты фенольной природы: коричные кислоты, флавоноиды, антоцианы, а также дитерпеновые химические соединения. Достоинством исследуемого способа является возможность одновременного концентрирования и определения эфирномасличных и фенольных компонентов. Результаты данного исследования представляют несомненный интерес для специалистов в области химии лекарственного растительного сырья.