bluuebunny/crossref_metadata_2025_split huggingface dataset:
MÉTODO DE REMEDIACIÓN DE BAJO COSTO PARA DISMINUIR LA CONCENTRACIÓN DE METALES PESADOS EN AGUAS CONTAMINADAS POR LA ACTIVIDAD MINERA
Authors: Alcántara-Malca Daniel Adolfo , Esenarro-Vargas Doris 
Published: May 2019

Las aguas de la actividad minera, las cuales se vierten a los cuerpos de agua naturales, generalmente contienen metales pesados en concentraciones que superan los límites máximos permisibles (LMP) o que superan los estándares de calidad ambiental (ECA). Los metales pesados en concentraciones más altas de lo permitido son muy perjudiciales para la vida del ser humano, los animales y las plantas de una localidad o región aledaña a la actividad de la empresa minera. En esta investigación de remediación se propone la aplicación de un método químico no convencional no costoso usando una base débil, complementado con un método de biorremediación usando cascarilla de arroz, para disminuir significativamente la concentración de los metales pesados de aguas provenientes de la actividad minera formal, en las serranías del Perú. Primero se ensayó con soluciones simples de concentraciones conocidas de metales pesados y luegose ensayó con soluciones más complejas de metales (con dos o más metales). Cuando se utilizaron dispersiones de jabón de 90 mL a 110 mL, los porcentajes de extracción de metales pesados oscilan en el rango de 95% a 99%. Cuando haymezclas de varios metales pesados cuyas concentraciones oscilan en el rango de 13 mg·L-1 -a 114 mg·L-1 y las cantidades de cascarilla de arroz oscilan de 2,0g a 3,25g, alcanzándose el pH a 6,0 – 7,5.
VIGILANCIA DEL DENGUE CON ENSAYO INMUNOENZIMÁTICO UMELISA IGM DENGUE PLUS
Authors: Alvarez-Maturell Elvio Luis , Pérez-Parrado Ileana , Álvarez-Ramírez Manuel Vicente 
Published: May 2019

El Dengue constituye la enfermedad viral transmitida por artrópodos de mayor importancia médica y la más importante en términos de morbilidad y mortalidad por consiguiente es importante la vigilancia del dengue. Se realizó un estudio observacional tipo transversal desde enero a diciembre del 2017 en el Laboratorio de Tecnología Avanzada SUMA del Centro Provincial de Higiene, Epidemiología y Microbiología (CPHEM) de Ciego de Ávila, Cuba. Las muestras de sueros fueron tomadas de personas con SFI (Síndromes Febriles Inespecíficos) a partir del 6to día de la fecha de inicio de los síntomas para detectar anticuerpos IgM contra dengue, para lo cual se utilizó el ensayo inmunoenzimático UMELISA IgM Dengue Plus. El mes de mayor reactividad fue octubre (25,99%) y los municipios más afectados con reactividad fueron Baragüa (20%), Ciego de Ávila (11,99%), Morón (11,86%) y Ciro Redondo (11,11%) que fueron municipios que tuvieron transmisión. El suero control interno positivo y negativo del ensayo estuvo bajo control estadístico. La concordancia entre los ensayos fue de 86,60 % y la prevalencia para el ensayo UMELISA DENGUE IgM Plus fue de10,32 %.
Effect of Spacer on Surface Activity and Foam Properties of Betaine Gemini Surfactants
Authors: Wang Lei , Liu Pei , Lai Xiaojuan , Wang Jie , Li Huaixin 
Published: May 2019

AbstractA series of betaine-type Gemini surfactants (Cs-BGS, where C is the methylene part of the spacer, s = 2, 4, 6) were synthesized from sodium 3-chloro-2-hydroxypropanesulfonate, oleamidopropyl dimethylamine and bromoalkane. The chemical structure of the prepared compounds was confirmed by 1H NMR, 13C NMR, IR spectra, and elemental analysis. Their critical micelle formation concentrations (CMC) in the aqueous solution at 25 °C were determined by measuring the surface tension and the electrical conductivity. As the length of the spacer increased, the values of their CMC and γcmc also increased. The surface tension measurements of C2-BGS revealed that the surfactant possesses a low CMC, is very efficient in reducing the surface tension, and is very strongly adsorbed at the air-water interface. In addition, the adsorption and micellization behavior of Cs-BGS was estimated from the efficiency of surface tension reduction (pC20), minimum average surface area per surfactant molecule (Amin), and standard free energies of micellization and adsorption. These properties are significantly affected by the spacers and the adsorption is more favored than the micellization.
Optimization of Biosorption Conditions for Surfactant Induced Decolorization by Anaerobic Sludge Granules
Authors: Gül Ülküye Dudu , İlhan Semra , İşçen Cansu Filik 
Published: May 2019

AbstractThe sorption of Remazol Black B (RBB) by dried anaerobic sludge granules (ASG) was examined in this study. The biosorption process was monitored based on the statistical optimization data of the batch reactor studies. In the factorial tests, 36 different tests were established by considering the variables such as temperature (25°C, 50°C), pH (1, 3, 5), dye concentration (100, 150, 200 mg/L) and cationic surfactant concentration (0, 0.5 mM). Also, it was intended to investigate the effect of cationic surfactant dodecyl trimethylammonium bromide (DTAB) on decolorization of the anionic dye RBB by ASG. The sorption isotherms and kinetics were determined for RBB removal. The biosorption of RBB was fitted with Langmuir isotherm and pseudo-second-order kinetic models. The oppositely charged dye and surfactant molecules interacted electrostatically. These electrostatic interactions improved the dye biosorption properties of ASG. Our results indicate that a surfactant can be used as an inducer in the treatment of dye-contaminated water. This is the first paper combining factorial experiment design and surfactant-accelerated decolorization to achieve more effective biosorption conditions.
Schiff' Bases as Corrosion Inhibitor for Aluminum Alloy in Hydrochloric Acid Medium
Authors: Abdel Hameed R. S. 
Published: May 2019

AbstractThree Schiff' bases (SB) were synthesized, characterized and evaluated as corrosion inhibitor for aluminum in 1.0 M HCl using chemical (weight loss) and electrochemical (open circuit potential, potentiodynamic polarization, and electrochemical impedance) techniques. The influence of temperature and concentration was investigated. It has been shown that the efficiency of corrosion inhibition increases with the inhibitor concentration and decreases with increasing temperature. The addition of the inhibitor molecules to the corrosive medium shifts the corrosion potential (Ecorr) to the nobler direction. It has been found that the adsorption of the used compounds obeys the Langmuir adsorption isotherm.
Study on the Complex System of Sodium Lauryl Diphenyl Ether Disulfonate and Dodecyl Dimethyl Hydroxyethyl Ammonium Chloride
Authors: Liu Jiajia , Yang Yang , Xie Yicheng , Xu Hujun 
Published: May 2019

AbstractSurface chemical properties of the mixed system of sodium lauryl diphenyl ether disulfonate (C12-MADS, an anionic surfactant with double hydrophilic groups) and dodecyl dimethyl hydroxyethyl ammonium chloride (K3, a cationic quaternary ammonium surfactant) along with different proportion have been studied at 298 K and 318 K. Synergistic parameters of the mixture in the mixed micelles and the mixed adsorption layer were also calculated by using the regular solution theory. The composition of the mixed micelles and of the mixed adsorption layer was obtained. The results show that the surface chemical properties of C12-MADS/K3 mixture are better than either of single system, and when the solution ratio (α1 = [n (K3)/n (C12-MADS + K3)]) is 0.7 and 0.9, the surface tension curve has a double inflection point which indicates a synergistic effect between the surfactant molecules. The complex system showed a strong synergistic effect in the mixed adsorption layer and the mixed micelles. The mixed system of C12-MADS/K3 has synergism in surface tension reduction effectiveness, surface tension reduction efficiency and mixed micelle formation. When α1 is 0.67, the synergistic effect is the strongest.
Heat Exchanger Corrosion in a Chlorinated Solvent Incinerator
Authors: Baker Brian A. 
Published: May 2019

Abstract
The thin plates within a type 309 stainless steel chlorinated solvent combustion preheater/heat exchanger designed to process fumes from a solvent coating process showed severe corrosion within 6 months of service. Within a year corrosion had produced holes in the plates, allowing gases to shunt across the preheater/exchanger. Metallographic examination of the plates showed that accelerated internal oxidation had been the cause of failure. Corrosion racks of candidate alloys (types 304, 309, and 316 stainless steels, Inconel 600, Inconel 625, Incoloy 800, Incoloy 825, and Inco alloy C-276) were placed directly in the hot gas stream, containing HCl and Cl2, for in situ testing. Results of this investigation showed that nickel-chromium corrosion-resistant alloys, such as Inconel 600, Inconel 625, and Inco alloy C-276, performed well in this environment. Laboratory testing of the same alloys, along with Inconel alloys 601, 617, and 690 and stainless steel type 347 was also conducted in a simulated waste incinerator nitrogen atmosphere containing 10% Co2, 9% O2, 4% HCl, 130 ppm HBr and 100 ppm SO2 at 595, 705, 815, and 925 deg C (1100, 1300,1500, and 1700 deg F). The tests confirmed the suitability of the nickel-chromium alloys for such an environment. Inconel 625 was selected for fabrication of a new preheater/exchanger.
Intergranular Corrosion/Cracking of a Stainless Steel Pipe Reducer Section in Bleached Pulp Stock Service
Authors: Chakrapani Durgam G. 
Published: May 2019

Abstract
A type 316 stainless steel pipe reducer section failed in service of bleached pulp stock transfer within 2 years in a pulp and paper mill. The reducer section fractured in the heat-affected zone of the flange-to-pipe weld on the flange side. The pipe reducer section consisted of 250 and 200 mm (10 and 8 in.) diam flanges welded to a tapered pipe section. The tapered pipe section was 3.3 mm (0.13 in.) thick type 316 stainless steel sheet, and the flanges were 5 mm (0.2 in.) thick CF8M (type 316) stainless steel castings. Visual and metallographic analysis indicated that the fracture was caused by intergranular corrosion/stress-corrosion cracks that initiated from the external surface of the pipe reducer section. Contributory factors were the sensitized condition of the flange and the concentration of corrosive elements from the bleach stock plant environment on the external surface. In the absence of the sensitized condition of the flange, the service of the pipe reducer section was acceptable. A type 316L stainless steel reducer section was recommended to replace the 316 component because of its superior resistance to sensitization.
Aircraft Accident Caused by Explosive Sabotage
Authors: Krishnan R.V. , Radhakrishnan S. , Raghuram A.C. , Ramachandran V. 
Published: May 2019

Abstract
Damage to a passenger aircraft that resulted from a midair explosion and subsequent emergency landing was investigated to determine the cause and location of the explosion. Extensive damage had occurred in the front toilet and cockpit areas and to the undercarriage and underside of the aircraft. Fractographic and surface examination of metal fragments (stainless steel and aluminum alloy) from damaged areas indicated that the accident was caused by an explosion in the front toilet. A reconstruction exercise confirmed this conclusion. Damage to the undercarriage and underside resulted from the emergency landing.
Corrosion Failure of a Chemical Process Piping Cross-Tee Assembly
Authors: Ellis Peter F. 
Published: May 2019

Abstract
A carbon steel piping cross-tee assembly which conveyed hydrogen sulfide (H7S) process gas at 150 to 275 deg C (300 to 585 deg F) with a maximum allowable operating pressure of 3 MPa (450 psig) ruptured at the toe of one of the welds at the cross after several years of service. The failure was initially thought to be the result of thermal fatigue, and the internal surfaces exhibited the “elephant hide” pattern characteristic of thermal fatigue. However metallographic failure analysis found that this pattern was the result of corrosion rather than thermal fatigue. Corrosion caused failure at this location because the weld was abnormally thin as fabricated. Thus, failure resulted from inadequate deposition of weld metal and subsequent wall thinning from internal corrosion. It was recommended that the cross-tee be replaced with a like component, with more careful attention to weld quality.
PENERAPAN MODEL PEMBELAJARAN KOOPERATIF TIPE TWO STAY TWO STRAY (TSTS) DALAM MENINGKATKAN HASIL BELAJAR BENTUK ALJABAR SISWA KELAS VII SMP
Authors: Arta Diantoro Syaiful Barsa , Mahsup Mahsup , Pramita Dewi 
Published: May 2019

Abstrak: Pembelajaran yang masih bersifat konvensional menyebabkan siswa merasa kesulitan dalam menyelesaikan masalah dalam setiap materi pembelajaran bentuk aljabar. Akibatnya hasil belajar siswa rendah. Tujuan peneltian ini adalah untuk meningkatkan hasil belajar siswa kelas VII SMP melalui penerapan model pembelajaran TSTS pada pokok bahasan bentuk aljabar. penerapan model pembelajaran TSTS adalah selalu melibatkan siswa dalam setiap penyelesaian masalah dan mencari informasi sendiri karena guru hanya sebagai fasilitator.Subyek pada penelitian ini yaitu kelas VII SMPN 18 Mataram yang terdiri dari 23 siswa. Adapun indikator keberhasilan penelitian ini adalah aktivitas belajar siswa dan guru dikatakan meningkat apabila berkategori baik, serta peningkatan hasil belajar siswa dikatakan meningkat apabila mencapai nilai rata-rata 70 dengan ketuntasan klasikal 75%. Hasil penelitian ini menunjukan terjadi peningkatan hasil belajar siswa dari siklus I sampai Siklus II. Rata-rata hasil belajar siswa pada siklus I 71,01 dengan ketuntasan klasikal 68,56%, sedangkan pada siklus II meningkat menjadi 82,61% dengan rata-rata nilai 76,38. Untuk rata-rata skor aktivitas siswa dan guru adalah 55,76 dan 80,77 yang termasuk berkategori cukup baik dan sangat baik. Kesimpulan penerapan model pembelajaran TSTS pada pokok bahasan bentuk aljabar dapat meningkatkan hasil belajar siswa kelas VII SMP. Abstract: The convention learning was difficult in teaching aljabar at the students. It made effect to improving student ability. The purpose of study to improve the student ability toward applying cooperative learning of TSTS in teaching aljabar at the students. Applying of TSTS learning model is followed by the students in problem solving and found out the information by their self because teacher as a facilitator. The subject of research were the students of seventh grade of SMPN 18 Mataram who are 23 students. The indicators of result study were the students learning activities and teacher were improved if it was good and KKM of score was about70, the classical point 75%. The result of study showed the applying cooperative learning TSTS model in teaching aljabar at the students was improved from cycle I until II. The result of score in cycle I 71,01 with classical score 68,56 %, meanwhile in cycle II was improved score 82,61 with mean score 76,38. The result of students and teacher was 55,76 and 80,77, it was included better. The concluded of applying TSTS in teaching aljabar can improved the students ability.
Analisis Sebaran Penelitian Skripsi Mahasiswa Program Studi Pendidikan Matematika Universitas Muhammadiyah Mataram
Authors: Pramita Dewi 
Published: May 2019

Abstrak: Penelitian ini bertujuan untuk mendeskripsikan sebaran jenis penelitian, tema yang popular serta kesulitan yang dihadapi mahasiswa dalam menyelesaikan atau menyusun skripsi program studi Pendidikan Matematika Universitas Muhammadiyah Mataram. Manfaat dari penelitian ini yaitu 1) diperoleh informasi tentang sebaran jenis penelitian dan tema penelitian yang paling sering atau paling banyak diambil oleh mahasiswa program studi Pendidikan Matematika Universitas Muhammadiyah Mataram; 2) kesulitan yang dialami mahasiswa dalam menyusun skripsi dapat menjadi landasan untuk evaluasi kualitas pembelajaran dikelas. Jenis penelitian yang digunakan yaitu penelitian deskriptif kualitatif. Subjek penelitian adalah mahasiswa yang sedang mengerjakan atau mengambil mata kuliah skripsi dalam rentang waktu bulan Oktober 2016 sampai dengan Maret 2017. Kesimpulan dari penelitian ini yaitu: 1) sebaran penelitian mahasiswa dominan pada penelitian kuantitatif dan penelitian R&D; 2) tema yang diminati (popular) dikalangan mahasiswa yang terkait dengan model penelitian; 3) kesulitan yang dihadapi mahasiswa meliputi penyusunan proposal, instrumen penelitian, pengolahan dan analisis data. Abstract: The purpose of the research to describe the distribution of undergraduate thesis,that conducted by the Mathematics Education Department students in terms of the research type, theme and also describe they difficulties experienced. The benefit of the research is 1) obtained the distribution of research themes are often or most taken by students of mathematics education department of Muhammadiyah Mataram University, 2)student difficulties in arrange they undergraduate thesis used to evaluate quality of learning.This research is a descriptive qualitative case study. The subjects of the research are Mathematics Education Department students whom taking a thesis course until Ocober 2016 to march 2017. Results of this research are: 1)distribution of the research are dominant in quantitative research and R&D research; 2)the most popular theme are about leraning model; 3) difficulties face by the student arebout arrange a proposal, research instrument, processing and analysis of data
Movimentos das narrativas na educação matemática brasileira e o lugar da história oral
Authors: Silva Marinéia dos Santos , Silva Heloisa da 
Published: May 2019

O artigo tem como objetivo a elaboração de uma compreensão inicial sobre a entrada e a movimentação das narrativas na Educação Matemática, bem como sobre o lugar da História Oral nesse movimento. Parte significativa deste estudo é resultado de uma pesquisa de doutorado em desenvolvimento, cujo objetivo é investigar o movimento de entrada, apropriação e circulação das narrativas na comunidade acadêmica da Educação Matemática, a partir dos grupos de pesquisa que estudam as narrativas na formação de professores que ensinam Matemática. Partindo do princípio de que as motivações das pesquisas com a História Oral na Educação Matemática diferem das demais pesquisas que abordam as narrativas nessa área, por seu envolvimento e compromisso com a historiografia, buscamos pontuar as singularidades e particularidades inerentes a essa metodologia – a História Oral. Salientamos também a complexidade e a pluralidade de temas que abordam as narrativas na Educação Matemática, bem como os espaços significativos, como os grupos de pesquisa, as associações, os congressos e os trabalhos científicos desenvolvidos pelos Programas de Pós-Graduação na área da Educação (Matemática) que corroboram a produção, a disseminação e o fortalecimento do movimento das narrativas na Educação Matemática.
Narrativas de professores de matemática em formação contínua
Authors: Scarlassari Nathalia Tornisiello , Lopes Celi Espasandin 
Published: May 2019

Este artigo pretende discutir aspectos da trajetória profissional de três professores de matemática, efetivos da rede municipal da cidade de Valinhos, São Paulo, que optaram por permanecer em contínua formação, participando efetivamente de um grupo de estudos colaborativo. A análise de suas narrativas (auto)biográficas, pautadas na reflexão de si, oferecerá elementos para responder a esta questão: como os professores, em processo de formação contínua, analisam sua trajetória profissional e percebem sua prática em sala de aula? Trata-se de uma pesquisa qualitativa do tipo narrativa, segundo os princípios da pesquisa (auto)biográfica, desenvolvida em uma das vertentes apontadas por Paula Perin Vicentini, Eliseu Clementino de Souza e Maria da Conceição Passeggi (2013), que toma as narrativas de si como práticas de formação e autoformação. Como resultado, salienta-se a necessidade dos professores em efetivo exercício docente de buscar formação contínua como educadores, aperfeiçoando sua prática na sala de aula e algumas potencialidades para o trabalho docente.
Narrativas de formação de professores de matemática sobre os Estágios Supervisionados
Authors: Abreu Maria das Graças , Megid Maria Auxiliadora Bueno de Andrade , Almeida Alessandra Rodrigues de 
Published: May 2019

Este artigo analisa experiências de formação de estudantes de um curso de licenciatura de Matemática de uma universidade privada do interior do Estado de São Paulo, que participaram de disciplinas relacionadas aos estágios docentes entre os anos de 2014 a 2018. São apresentadas e colocadas em discussão as orientações e estratégias de organização das disciplinas, bem como a execução e a realização das mesmas pelos envolvidos. Por estratégia reflexiva, foram adotadas as narrativas de vida e de formação, tanto no decorrer das disciplinas como na apresentação de um relatório final. Tais ações possibilitaram o processo reflexivo dos licenciandos sobre si e sobre a formação profissional. As narrativas, produzidas nesse percurso formativo, proporcionaram rememorar as experiências vivenciadas e também confrontar expectativas, sonhos e realidade, tanto profissional quanto da realidade educacional. Foi possível identificar os efeitos dessa proposta de formação, como propulsora de reflexão sobre o percurso de aprendizagem docente, em que os participantes, ao narrarem suas experiências, encontraram possibilidades para uma ampliação da capacidade de conhecer-se e reconhecer-se na complexidade do ambiente formativo e educacional.
The Pollen Morphology of Dragon’s Blood Rattans (Daemonorops spp.) from Sumatra.
Authors: Asra Revis , Yelianti Upik , Witono Joko Ridho 
Published: May 2019

Revis Asra, UpikYelianti & Joko Ridho Witono. 2019. The Pollen Morphology of Dragon’s Blood Rattans(Daemonorops spp.) from Sumatra. Floribunda 6(2): 35–40. — Dragon’s blood rattans (Daemonorops spp.) or locally known as jernang, is one of the well anticipated and economically valuable non timber forest products from Sumatra. The species group produces a red resin on the fruit scale and is one of the main resources of some medicines and colouring. The characteristic of pollen morphology was one of important role in determining the pollination system of dioecious species such as dragon’s blood rattans. The purpose of this study was to examine the pollen characteristic and its relation to the pollination system of four species of dragon’s blood rattans from Sumatra, i.e. Daemonorops aff. propinqua Becc., D. propinqua Becc., D. draconcella Becc. and D. didymophylla Becc. Pollen of dragon’s blood rattans were collected from the secondary forest of Jambi and Bukit Duabelas National Park, then stored in FAA solution, followed by observation using SEM (Scanning Electron Microscope). The pollen of Daemonorops aff. propinqua and D. propinqua have aperture and irregular ex-ornamentation type, while D. draconcella is monocolpus and D. didymophylla is tricolpus. The pollen of Daemonorops aff. propinqua and D. propinqua show uneven exines while the others Daemonorops have even exines. Characters of smooth pollen grainsin D. draconcella and D. didymophylla are indicated that those species associated with wind pollination, whereas sculptured pollen grains in Daemonorops aff. propinqua and D. propinqua are associated with insect pollination.