bluuebunny/crossref_metadata_2025 huggingface dataset:
LEVEL BERPIKIR VAN HIELE DAN KEMAMPUAN SPASIAL: APAKAH PENGARUHNYA TERHADAP KETRAMPILAN HOTS MAHASISWA?
Authors: Hendroanto Aan , Fitriyani Harina , Anggoro Rostien Puput
Published: May 2019

Kemampuan berpikir tingkat tinggi (HOTS) memiliki peranan penting bagi siswa terutama di abad 21. HOTS dipandang sebagai kemampuan dasar yang wajib dikembangkan terutama pada pembelajaran matematika. Oleh karena itu penting bagi calon guru pendidikan matematika untuk mengembangkan kemampuan HOTS. Artikel ini bertujuan untuk menganalisis kemampuan HOTS mahasiswa pendidikan matematika Universitas Ahmad Dahlan dalam mengerjakan soal HOTS pada mata kuliah geometri. Penelitian ini menggunakan metode penelitian deskriptif kualitatif. Ada sebanyak 3 orang mahasiswa yang telah mengambil mata kuliah geometri ruang dengan kemampuan matematika yang berbeda-beda. Instrument yang digunakan yaitu kuesioner berupa 5 soal geometry ruang berbasis HOTS. Hasil yang diperoleh yaitu bahwa mahasiswa mengalami kesulitan dalam memahami soal dan menentukan strategi yang akan digunakan. Beberapa mahasiswa juga kesulitan dalam menggambarkan situasi objek geometri pada soal.
Continuing Presence of Discarded Bodies: Occupational Harm, Necro-Activism, and Living Justice
Authors: Kim Eunjung
Published: May 2019

This essay explores the coexistence of struggles against the foreclosure of disabled people’s lives and against occupational illness, debilitation, and deaths caused by the manufacturing process of electronics in South Korea. Starting from the two activist campsites set up in Seoul and the historical backgrounds of occupational health movement, I draw on two documentary films, The Empire of Shame (2014) and Factory Complex (2015), that depict workers who became ill and those who died due to toxic exposure at semiconductor manufacturing plants. Beyond commemoration, necro-activism emerges in the form of persistent involvements of dead bodies, mourning, and objects representing death as important agents for making claims for justice. Taking into account political and historical differences of locations in which disabled people are positioned differently in the global order redirects us from the language of worth toward sociality, collective reframing of suffering and disability, and justice as an ongoing practice of everyday life and afterlife.
Transcription Work and the Practices of Crip Technoscience
Authors: Hickman Louise
Published: May 2019

The following essay considers the emergence of transcription work provided by Communication Access Real-time Translation (CART) operators in academic spaces for d/Deaf and hard of hearing individuals in order to foreground the practice of access. How do we account for the distribution and attribution of access in a way that is mediated across human and non-human objects? I draw on crip technoscience to illuminate the value of the stenographer’s labor and their dictionary software as an inherent part of the production of knowledge.
Guías clínicas para el tratamiento de la rosácea
Authors: Molina Ana Lucía , Londoño Ángela , Escobar Sara María , Benítez Marcela
Published: May 2019

La rosácea es una condición inflamatoria crónica que afecta la piel y los ojos, caracterizada por eritema transitorio o persistente, pápulas y pústulas, y cuando está en etapas avanzadas, se presenta con “fimatosis”. Existen múltiples modalidades terapéuticas para esta entidad, pero es poco claro cuál es la más efectiva.Objetivo. Recolectar y analizar los diferentes estudios que hay en la literatura científica sobre el tratamiento de la rosácea y dar recomendaciones clínicas basadas en el nivel de evidencia.Métodos. La búsqueda de artículos sobre las diferentes modalidades de tratamiento de la rosácea pápulo-pustular, eritemato-telangiectásica y “fimatosa”, se hizo en las bases de datos Embase, Medline, Lilacs, Ovid, con el buscador Pubmed, desde enero de 1980 hasta junio de 2011. Luego de recolectar la literatura científica disponible, se analizó la información y se calificó la calidad de los estudios utilizando las escalas de Jadad para ensayos clínicos de asignación aleatoria, y CASPE para estudios de casos y controles, cohortes y estudios cualitativos. Finalmente, se dan recomendaciones clínicas según el grado de evidencia encontrado.Resultados. Se encontraron 178 artículos de las diferentes modalidades terapéuticas. En la rosácea pápulo-pustular los tratamientos con mayor nivel de evidencia son el metronidazol, el ácido azelaico, la sulfacetamida y la doxiciclina; en la rosácea eritemato-telangiectásica, las modalidades más utilizadas son los medios físicos, y en la rosácea “fimatosa”, el tratamiento de primera línea es el láser de CO2.Conclusiones. Este documento presenta una revisión actualizada de la literatura científica y formula recomendaciones terapéuticas basadas en el mejor nivel de evidencia que se encontró. Su implementación permitirá la unificación de criterios, con el objetivo de ofrecer un mejor tratamiento a los pacientes con la enfermedad.
The Modernisation of the Court System in the Grand Duchy of Lithuania: Changes to the Organisation of the Local District Courts and Regulation of Judges’ Duties in 1764–1793
Authors: Šmigelskytė-Stukienė Ramunė
Published: May 2019

In the mid-18th century, with the spread of the ideas of the Enlightenment, fundamental reforms of the state’s governance were introduced in the Polish-Lithuanian Commonwealth. Part of the state’s modernisation concerned the reform of the court system, considered by 18th-century political theorists to be one of the composite branches of the state administration (alongside the treasury, the police and the army). During the reign of Stanislas Augustus Poniatowski, the work of the courts of first instance underwent reform on several occasions in Poland and Lithuania: with the passing of laws in 1764, 1792 and 1793 on the structure and organisation of the activities of the castle and land courts, the existing court system was changed, as was the procedure for electing judges, also defining the scope of competency of the courts, regulating court activities and the duties of judges, introducing new requirements for the handling of court procedural documents, and the calculation of judges’ working hours. During the course of the introduction of these reforms, principles reflecting the administrative ideas of the Enlightenment were gradually entrenched in the court system of the Polish-Lithuanian Commonwealth, which concerned the election of judges and other court officials, the acceptance of collegial decisions, the elimination of the influence of any blood and marital ties, and the principles for remuneration, seeking to introduce stricter requirements for the qualification of judges.

In this article, based on legislation on the organisation of court activities passed at the diets (Sejm) of the Polish-Lithuanian Commonwealth and documents from the dietines (sejmiki) of the Grand Duchy of Lithuania, the author seeks to analyse changes to the activities of the courts and the regulation of judges’ duties, and reforms made in the court chanceries between 1764 and 1793.
The Career of the Doctor of Medicine and Philosophy Stefano Lorenzo Bisio in the Grand Duchy of Lithuania
Authors: Ramonaitė Monika
Published: May 2019

The doctor of medicine and philosophy Stefano Lorenzo Bisio (1724–1800?) worked in the Grand Duchy of Lithuania between 1762/3 and 1787. During this quarter of a century, he earned renown as a private physician to magnates, an innovator in the science of medicine, and as one of the founders of academic medicine in the Grand Duchy of Lithuania. Regardless of this, only one of the last stages of Bisio’s career has received much attention in historiography so far, his becoming the first head of the College of Medicine, established at Vilnius University in 1781. In this article, I seek to give as comprehensive as possible a presentation of Bisio’s entire career in the Grand Duchy of Lithuania, discussing thoroughly his academic activities and achievements. Through these achievements, I hope to show that he was one of the first to apply West European anatomical, pathological and clinical medical knowledge from the Age of Enlightenment, which itself was undergoing qualitative breakthroughs, in the GDL. In the article, I also correct and present new biographical facts about S.L. Bisio, his birth and death dates, work and education placesfamily, and work relations.
Sinema ve Dans Arasındaki İlişki: Müzikal Filmlerinde Hareket İmge
Authors: UĞUR Aysu
Published: May 2019

Sanat insanın dünyayı anlamlandırmasına ve
kendini ifade etmesine yardımcı olmaktadır. Tüm sanat dalları çeşitli
dönemlerde birbirinden etkilenmiştir. Sinemanın 7. Sanat olarak görülmesi diğer
sanatlarla güçlü bir şekilde etkileşim halinde olmasından kaynaklıdır. Sinema
görsel sanatlar içinde etkili bir yere sahiptir ve görsel- işitsel tekniklerin
kullanılması açısından esnektir. Sinemanın diğer sanatlarla ilişkisinde en çok
incelenen konular edebiyat, resim ve fotoğraftır. Ancak bu çalışmada dans ve
sinema arasındaki ilişkiden doğan müzikal filmler, hareket-imge bağlamında
incelenmiştir. Hareket, dansın ve sinemanın özünü oluşturmaktadır ve bu
hareketlerin kurgusu anlam yaratmada önemlidir. Sessiz sinema döneminde Mack
Sennett, Charlie Chaplin güldürülerini bedenin hareketiyle anlatmıştır ve beden
sinemada bir imge haline gelmiştir. Müzikal filmlerde öne çıkan beden,  müzik ve dansın etkisiyle estetik bir forma
bürünmüştür, filmlerin anlatı yapısı müzikal türüne özgü değişmiştir. Deleuze
sinemanın hareket bloklarından oluştuğunu söyler ve sinemayı hareketle düşünen
bir sanat olarak görmektedir. Bu yaklaşımdan yola çıkarak müzikal filmlerindeki
görsel imajların, sinematografik unsurlarla ve hareket ile güçlendiğini
söylemek mümkündür. Bu bağlamda Damien
Chazelle ’in yönettiği ‘’La
la land’’ (2016) filminin örneklem olarak seçilmesinde düşsel dünyayı kuran
hareket-imgeler etkili olmuştur.  Film
analizi yöntemiyle filmdeki hareket imajlar incelenmiş ve müzikal türünün
kendine özgü kodları açıklanmıştır.
Proof of Participation Protocol
Authors: Mielberg Egger L.
Published: May 2019

We present an innovative approach to the design of a decentralized asynchronous protocol that will, first, let business of any kind realize any project that can be formalized on a “step-by-step” basis, second, allow its users to completely solve Byzantine problem with one or many contracts-related associative network (subnetwork), third, allow business to design, if needed, a strictly economy-based model that can be stable for a long period of time.The innovative approach is totally based on the technology of Smart Transaction [1].The protocol is mainly focused on a practical realization of economical business contracts of any kind.
Neurochain
Authors: Mielberg Egger L.
Published: May 2019

In a system where there are tons of information of different types it is always hard and frequently impossible to tie the effect to the cause. There is also a challenge to find relevant data quickly, especially in case of absence of classification algorithm that is capable of working with different fields of business and science in parallel.We propose a mechanism for building a network of associative chains that are decentralized to each other. The network allows its participants to build quickly an associative chain from “effect-to-cause”. This feature of the network is extremely useful for identification of a scam activity.The mechanism is based on two technologies, “Smart Transactions” [1] and “Proof of Participation Protocol” [2].
Digital Bank
Authors: Mielberg Egger L.
Published: May 2019

Decentralization of BANK services would allow its users, first, to primarily earn money, second, to extremely reduce document routines, third, to make their activity more transparent and secure.We propose a new concept of BANK, a digital BANK that never can be a bankrupt and has professional skills and degree of activity of its customers as a main capital.
Sphere Real Money or Electronic Surrogate
Authors: Mielberg Egger L.
Published: May 2019

Decentralized nature of Sphere electronic currency introduces several new properties that the traditional one does not have.Here, we shortly review all functions and properties of real (fiat) money and propose new features that belong to Sphere.
Abur
Authors: abur marsel
Published: May 2019

Tugas Geografi Ekonomi
Meningkatkan Sumber Daya Guru Untuk Menjamin Mutu Pendidikan Melalui Supervisi Pendidikan
Authors: Yulianti Wira
Published: May 2019

guru merupakan salah satu unsur yang terpenting dalam pendidikan karena baik buruknya kualitas pendidikan sangat ditentukan oleh standar kualitas guru tersebut. dalam neningkatkan kualitas sumber daya guru dalam pendidikan, guru sutu komponen sumber daya manusia yang harus dibina dan dikembangkan terus menerus untuk mengembangkan potensi yang dimiliki guru maka harus dibantu oleh sesama guru untuk saling bekerja sama dalam pendidikan. sehingga menghasilkan guru professional yamg memiliki tugas untuk mendidik, melatih, mengajar, membimbing, menilai dan mengevaluasi peserta didik dapat mendukung dalam pencapaian tujuan untuk menjadikan guru professional. karena pengaruh perubahan yang sangat cepat mendorong guru-guru untuk terus belajar menyesuaikan diri dengan perkembangan ilmu pengetahuan dan teknologi serta mobilitas dengan masyarakat. supervisi pendidikan memiliki peranan yang penting dalam meningkatkan sumber daya guru yang menghasikan guru yang professional.
Upaya Meningatkan Motivasi Belajar Matematika menggunakan Topik Astronomi dan Fiqih
Authors: Setiawan Adib Rifqi
Published: May 2019

Penelitian kuasi-eksperimen dengan desain pengaruh imbangan ini menggunakan topik astronomi dan fiqih untuk meningkatan motivasi belajar siswa dalam matematika.
A Glance of Elementary Mathematics’s Portrayal
Authors: Setiawan Adib Rifqi
Published: May 2019

This work provide brief description about elementary mathematics as essentials of basic principles to teaching mathematics, especially for practical users, generally for public in less economically developed country.
PERAN SUPERVISI PENDIDIKAN DALAM MENINGKATKAN MUTU PENDIDIKAN DI INDONESIA
Authors: NASUTION TIA AGUSTINA
Published: May 2019

Pendidikan di Indonesia diharapkan dapat menghasilkan generasi penerus bangsa yang produktif, kreatif, inovatif dan afektif serta berprestasi dalam bidang akademik maupun non akademik sehingga dapat bersaing di kancah nasional dan internasional. Diperlukan adanya supervisi pendidikan untuk meningkatkan prestasi belajar siswa dan membentuk karakter siswa sehingga dapat meningkatkan mutu pembelajaran serta mencapai tujuan pendidikan secara nasional. Peningkatan mutu pendidikan harus dilakukan secara berkesinambungan dan dilakukan oleh seluruh elemen yang terlibat dalam proses pembelajaran disekolah termasuk peserta didik, tenaga pendidik, tenaga kependidikan, orang tua serta masyrakat dan lingkungan sekitar. Dengan adanya kerjasama diantara semua elemen tersebut maka mutu pendidikan dapat ditingkatkan sehingga tidak tertinggal dengan perkembangan ilmu dan teknologi yang sangat pesat.
The Concept of Self in Mindfulness-Based Cognitive Therapy and Morita Therapy - The Similarities & Differences in the Therapeutic Mechanisms, Philosophies, and Methods
Authors: Hu Hiroe , Roth Harold
Published: May 2019

While the effects of mindfulness practices on the self are not widely recognized, a reduction in self-centered or “self-referential” processing stands as one of the central therapeutic mechanisms of mindfulness-based psychotherapy. In this literature-based research, I compared two cultural variations of mindfulness-based psychotherapy: Mindfulness-Based Cognitive Therapy (MBCT), developed recently in the West, and Morita Therapy, founded in Japan during the 1920’s based on Zen Buddhism. Despite the vast cultural/historical gap between them, they are strikingly similar in a number of respects. The most significant similarity is that they both use mindfulness as their primary therapeutic means; both, in turn, involve a change in the conception of ‘self’ via mindfulness. Despite the remarkable similarities, there are also discrepancies in their philosophies, methods, and techniques, which likely arose from the difference between the western individualistic and eastern collectivist values. Throughout this thesis, I show that the self can be understood as a two-layered structure. There is an inner layer—the operating locus of mindfulness—that function similarly irrespective of culture context, which may be responsible for some of the similarities between the therapies. There is also an outer layer that varies across cultures—a possible source of the differences in the therapies.
Approach and Avoidance Patterns in Reward Learning Across Domains: An Initial Examination of the Social Iowa Gambling Task
Authors: Case Julia , Olino Thomas M
Published: May 2019

The current study examines learning patterns in response to both monetary and social incentives through both approach and avoidance behaviors using modified versions of the Iowa Gambling Task. Specifically, we investigated learning in response to both positive and negative feedback in a sample of 191 undergraduate students. The social task was a novel paradigm, and social feedback were images of faces displaying positive and negative emotions. We examined internal validity of the tasks through modeling changes in approach and avoidance. We also explored associations between approach and avoidance learning and individual differences in anxiety and social anxiety, depression and well-being, general anhedonia and social closeness, and fun-seeking, using multilevel models (MLMs). Results showed that both the monetary and social tasks demonstrated learning as shown by decreases in plays on disadvantageous decks across the task. Additionally, we found that overall task performance on the monetary task was associated with fun-seeking and overall task performance on the social task was associated with fun-seeking and depressive symptoms. Initial findings suggest promise for the novel task in theexamination of social avoidance learning.
Journeys, Frontiers and Medical Education
Authors: Roseby Robert
Published: May 2019

Not Applicable.
Sexual Dimorphism in Permanent Maxillary and Mandibular Canine of Medical Students in Gandaki Medical College, Nepal
Authors: Shrestha Bijayata
Published: May 2019

Introduction: Gender determination is important for identification in forensic practice. Odontometrics plays an important role in sex determination in young individuals where secondary sexual characters are yet to be developed.

Objective: The objective was to re-evaluate the previous finding of the sexual dimorphism in Mesiodistal (MD) and Buccolingual (BL) dimension of maxillary and mandibular canine in the study population being Medical Students of Medical College in province 4 of Nepal.

Methodology: This is a cross sectional study conducted on the study cast of 40 male and 40 female medical students of academic year 2017/18 of Gandaki Medical College, Nepal, of age group 18-24 from October to December 2017. The MD and BL dimensions of all the four canines were measured using digital vernier's caliper. Data were compared using descriptive statistics, student's t-test and paired sample t test. P<0.05 was found statistically significant.

Results: Statistically significant sexual dimorphism was found in MD and BL dimension of maxillary and mandibular canine with males' canine measuring larger than females'. The left mandibular canine was found to be the most dimorphic in term of BL dimension among the canines.

Conclusion: The present study exhibited the buccolingual dimension of the left mandibular canine as the most dimorphic tooth. Further studies using large representative sample from all the provinces has to be conducted to quantify and generalize the result among the Nepalese Dentition.
Generalities on finite element discretization for fractional pressure diffusion equation in the fractal continuum
Authors: Sánchez Chávez H. D. , López-Ortiz C. A. , Flores-Cano And L.
Published: May 2019

In this study we explore the application of the novel fractional calculus in fractal continuum (FCFC), together with the finite element method (FEM), in order to analize explicitly how these differential operators act in the process of discretizing the generalized fractional pressure diffusion equation for a three-dimensional anisotropic continuous fractal flow. The master finite element equation (MFEE) for arbitrary interpolation functions is obtained. As an example, MFEE for the case of a generic linear tetrahedron in $\mathbb{R}^3$ is shown. Analytic solution for the spatial variables is determined over a canonical tetrahedral finite element in global coordinates.
MODELO DE DISEÑO PARA LA ACREDITACIÓN ANALÍTICA DE LABORATORIOS EN BIOLOGÍA Y QUÍMICA AMBIENTAL
Authors: Argota-Pérez George , Iannacone Jose Alberto , Castañeda-Pérez Luz , Huarancca Contreras Patricia
Published: May 2019

En múltiples ocasiones, la toma de decisiones ambientales depende de la respuesta analítica emitida por un laboratorio y no siempre, los resultados químicos o biológicos se sustentan por la trazabilidad metodología que requiere su validación. El propósito del estudio fue desarrollar un modelo de diseño para la acreditación analítica de laboratorios en biología y química ambiental. El diseño del modelo referido como eje dinámico de primer orden, al proceso de medición donde otros cuatro ejes dinámicos de segundo orden confluyeron son denominados: I) proceso de la muestra (muestra), II) proceso de realización (métodos), III) proceso de seguimiento y mejora (resultados) y IV) proceso institucional (laboratorio). Cada uno de los ejes de segundo orden presentó diversos criterios de validez para asegurar el proceso de medición específica. Se concluyó que el diseño del modelo permitió asegurar la confiabilidad de los resultados.
OPTIMIZACIÓN ÁCIDA PARA LA BIOEXTRACCIÓN ECOTOXICOLÓGICA DE METALES EN ÓRGANOS DIANAS
Authors: Argota-Coello Humberto , Argota-Pérez George , Iannacone Jose Alberto , Fimia-Duarte Rigoberto
Published: May 2019

El propósito del estudio fue optimizar una mezcla ácida para la bioextracción ecotoxicológica de metales en órganos diana. Desde junio del 2010 hasta junio del 2017 fueron seleccionaron seis tipos de ácidos: HF, HCl, HNO3, HClO4, H2SO4 y H3PO4 diseñándose 15 combinaciones (dos tipos de ácidos) y 17 combinaciones (tres tipos de ácidos) para comparar sus resultados con los valores patrones de referencias certificadas sobre peces no expuestos a contaminación por metales: DOLT-3 (“Dogfish Liver”, hígado de tiburón) y DORM-2 (“Dogfish Muscle”, músculo de tiburón). Los registros más próximos correspondieron a la mezcla: HNO3-HClO4-H2SO4 realizándose luego, otros 6 diseños de experimentos donde la combinación HClO4-H2SO4-HNO3 fue la más precisa según los registros. Después, nuevas proporciones fueron evaluadas: 3:4:3; 5:2:6 y 7:1:15, alcanzándose aceptables resultados mediante la tercera siendo la re-suspensión total de las sales húmedas mediante el HNO3 (valoración final: 1-8mL). Cuando se usó más de 5 mL de HNO3, no se observó diferencias estadísticamente significativas (p<0,05) con los valores certificados. La cuantificación se realizó por espectrometría de emisión atómica con plasma inductivamente acoplado con la digestión ácida testeada y con el biomodelo Gambusia punctata (Poey, 1854) bajo condiciones diferenciales de contaminación.
ECOTOXICOLOGÍA COMO HERRAMIENTA PREDICTIVA EN LA EVOLUCIÓN SOSTENIBLE DE LOS SISTEMAS ACUÁTICOS
Authors: Argota-Pérez George , Iannacone Jose Alberto
Published: May 2019

La contaminación ocasiona deterioro de los componentes ambientales donde determinadas ramas del saber aplicativo permiten reconocer el grado de equilibrio a nivel de ecosistema. El propósito del estudio fue indicar la ecotoxicología como una herramienta predictiva sobre la evolución sostenible de los sistemas acuáticos. Mediante el análisis de contenido sobre aspectos teóricos y usos prácticos referido a la ecotoxicología se consideró, durante 10 años (2008- 2018), la calidad ambiental y evolución sostenible del ecosistema San Juan de Santiago de Cuba, Cuba. Las variables de interés analizadas fueron el factor de condición biológico (K) y la bioacumulación de metales (Pb y Cd) en las branquias (órganos diana) de la especie de pez Gambusia punctata (Poey, 1854) (Poeciliidae), el cual fue seleccionado en categoría de biomonitor. Se observó, diferencias estadísticamente significativas en el indicador K (para ambos sexos), el cual se midió cada 5 años (2008, 2013 y 2018) donde sus valores disminuyeron (machos / 2008: 0,45–0,47; 2013: 0,43–0,44; 2018: 0,37–0,41; hembras / 2008: 0,63–0,66; 2013: 0,58–0,61; 2018: 0,55–0,58) mientras que, no hubo diferencias estadísticamente significativas con relación a la bioacumulación de los metales (considerados como valores promedios entre machos y hembras (ug·g-1); Pb / 2008: 0,04±0,01; 2013: 0,03±0,02; 2018: 0,04±0,02; Cd / 2008: 16,44±0,017; 2013: 16,77±0,011; 2018: 16,78±0,008). Se concluyó que, existió limitada estabilidad ambiental en el tiempo y por ende; poca sostenibilidad como recurso ecosistémico para San Juan, siendo reconocido mediante el análisis de los biomarcadores los cuales se basaron en los preceptos de la ecotoxicología.
PROBLEMA CIENTÍFICO DE INVESTIGACIÓN
Authors: Argota-Pérez George
Published: May 2019

El problema científico aunque puede redefinirse, es la estructura metodológica más compleja de plantear, ya que la correcta identificación de las variables debe garantizar la delimitación del objeto de investigación, posible tiempo empleado, claridad conceptual sobre área de investigación involucrada, inmediatez de interrogantes como guías a dilucidar y la disponibilidad objetiva de recursos involucrados. Asimismo, alberga la curiosidad de transformar algunos efectosindeseados que justifi can, causas no resueltas. El planteamiento del problema científi co de investigación requiere para su justificación, originalidad, trascendencia, nivel de actualización y relevancia; además, el uso de herramientas intelectuales disponibles. El presente trabajo tiene el propósito de describir un algoritmo práctico para el correcto planteamiento del problema científico de investigación.
Fatigue Cracking in a Stainless Steel Welded Exhaust Hose Assembly
Authors: Levy Eli
Published: May 2019

A failure analysis was conducted to determine the cause of recurring failure of flexible bellows in an exhaust hose assembly. The bellows were made of type 321 stainless steel. Visual examination showed that cracks followed a path along the seam weld in the bellows. Most of the cracks followed a multidirectional/circular pattern, occasionally chipping off the convolutions, an indication of high-resonance fatigue-type cracking. Scanning electron fractography showed fatigue striations throughout the fracture surface. The microstructure consisted of relatively large grains and an abnormal degree of titanium-base stringers. Wall thickness was about 0.15 mm (0.006 in.) underside. It was concluded that the high vane pass frequency excited the natural vibration of the bellows to a higher resonance and cracked the bellows after a relatively short service period. The assembly was redesigned, and no further cracking occurred.
Failure of a Brass Pipe Nipple
Authors: D'Antonio Carmine
Published: May 2019

A brass (CDA alloy 230) pipe nipple that was part of a domestic cold water bath system failed two weeks after installation. Macrofractography, SEM examination, metallography, and chemical analyses were performed on specimens cut through the main fracture surface. The physical and background evidence obtained indicated failure due to cracking initiated by stamped markings on the pipe wall and extended by high circumferential residual stresses. It was recommended that annealed pipe be used.
Failure of a Type 317L Stainless Steel Clad Bottom Cone of an Acid Sulfite Pulping Batch Digester
Authors: Chakrapani Durgam G.
Published: May 2019

A segment of a stainless steel clad bottom cone of an acid sulfite pulping batch digester failed from severe corrosion loss. The digester was fabricated of 19 mm (34 in.) low-carbon steel with 3.8 mm (0.15 in.) type 317L stainless steel cladding. The manufacturing method for the cladding was unknown. Visual and metallographic analyses indicated that the failure was from transgranular stress-corrosion cracking (TGSCC), which caused extensive cracking and spalling of the cladding and was localized in a segment of the bottom cone. The remainder of the digester cladding was unaffected. The TGSCC was attributed to high, locked-in residual stresses from the cladding process. It was recommended that the bottom cone replacement segment be stress relieved prior to installation.
Failure Analysis of a Carrier Shaft
Authors: Bravenec Edward V.
Published: May 2019

A 25 mm (1 in.) diam carrier shaft failed suddenly during operation. The shaft failed near the toe of the 4.8 mm (316 in.) frame-to-shaft 60 deg and 120 deg submerged metal arc (SMA) tack welds after an unknown time in service. Material specifications called for the shaft to be made from SAE 1018 cold-rolled carbon steel. Carrier assembly components were made from type 300 stainless steel, and all nuts, spacers, and washers were to be SMA tack welded to the stainless steel frame. Chemical analyses (OES, SEM/EDS) showed the shaft to actually be made from SAE 1050 high-carbon steel and that a low-carbon steel welding procedure had been used. This resulted in incipient cracks in the stainless steel weld metal near the toes of the component-to-shaft welds. The hardnesses of the heat-affected zones were as high as 58 HRC, and they were grain coarsened. The parting of the shaft was determined to have been caused by an impact failure mechanism, with the origin at the incipient cracks in the weld metal. Additionally, the coarsened heat-affected zones were found to be hydrogen embrittled. The primary cause of the failure was the use of an unspecified material.
Failure of a Flexible Pump Connector
Authors: D'Antonio Carmine
Published: May 2019

A stainless steel flexible connector failed after a short period of service. Visual examination of the failed part revealed that a fracture had occurred in the thin-walled stainless steel bellows brazed into the flanges at each end. Surface examination by SEM fractography showed that failure of the bellows occurred via fatigue. The crack in the bellows had widened considerably after the fracture, and the bellows had been severely compressed on the fracture side prior to failure. Based on these observations, it was concluded that bellows had been damaged prior to installation. The damage resulted in high mean tensile stresses upon which were superimposed cyclic stresses, with fatigue failure the final result.
Gaseous Corrosion of a Heat-Resistant Alloy (Metal Dusting)
Authors: Colwell Richard L.
Published: May 2019

A 150 mm (6 in.) diam, 1.6 mm (0.065 in.) thick alloy 800 1iner from an internal bypass line in a hydrogen reformer was removed from a waste heat boiler because of severe metal loss. Visual and metallographic examinations of the liner indicated severe metal wastage on the inner surface, along with sooty residue. Patterns similar to those associated with erosion/corrosion damage were observed. Microstructural examination of wasted areas revealed a bulk matrix composed of massive carbides, indicating that gross carburization and metal dusting had occurred. X-ray diffraction analysis showed that the carbides were primarily chromium based (Cr23C7 and Cr7C3). The sooty substance was identified as graphite. Wasted areas were ferromagnetic and the degree of ferromagnetism was directly related to the degree of wastage. Three actions were recommended: (1) inspection of the waste heat boiler to determine the extent of metal damage in other areas by measuring the degree of ferromagnetism, (2) replacement of metal determined to be magnetic, and (3) closer monitoring of temperatures in the region of the reformer furnace outlet.
Service Failure of a Die Insert Made From AISI D2 Tool Steel
Authors: Menke Hector H.
Published: May 2019

An AISI D2 tool steel insert from a forming die used in the manufacture of automotive components failed prematurely during production. Results of various analyses and simulation tests indicated fatigue failure resulting from improper heat treatment. The fatigue fracture originated because of a highly stressed condition produced by a sharp corner combined with low toughness from ineffective tempering. It was recommended that 25 other inserts that belonged to the same die be double tempered.
Failure of a Stainless Steel Hip Fracture Fixation Device
Authors: D'Antonio Carmine
Published: May 2019

A type 316L stainless steel “Jewett nail” hip implant failed after 2 months of service. Fracture occurred through the first of five screw holes in the plate section. Microscopic examination of mating fracture surfaces showed that failure had initiated at the outside (convex) surface of the plate and proceeded through its thickness. The fracture morphology was characteristic of fatigue. A beveled area on the inside surface of the plate indicated that the implant had been fractured for some time prior to removal. Metallographic examination of samples cut from the plate section revealed a series of hidden repair welds on the inside surface of the plate in the vicinity of the fracture. Comparison of the microstructure in the area of the fracture with that in an area away from the weld indicated that the repair welding had resulted in the creation of an annealed, softened zone. Manufacturers should never attempt to salvage this type of critical device by welding or any other procedure that might compromise its integrity.
Failed Missile Launcher Detent Spring
Authors: Wechsler Gary , Champagne Victor K. , Pepi Marc
Published: May 2019

A missile detached from a Navy fighter jet during a routine landing on an aircraft carrier deck because of a faulty missile launcher detent spring. Visual inspection of Inconel 718 detent spring assembly revealed that four of the nine spring leafs comprising the assembly were plastically deformed while two of the deformed leafs did not meet minimal hardness or tensile requirements. Liquid penetrant testing revealed no cracks or other surface discontinuities on the leaf springs. Material sectioned from the soft spring leafs was heat-treated according to specifications in the laboratory. The resultant increase in mechanical properties of the re-heat-treated material indicated that the original heat treatment was not performed correctly. The failure was attributed to improper heat treatment. Recommendations focused on more stringent quality control of the heat-treat operations.
Feedwater Piping Erosion at a Waste-to-Energy Plant
Authors: Weiss Wendy L. , McClave Brian
Published: May 2019

The carbon steel feedwater piping at a waste-to-energy plant was suffering from wall thinning and leaking after being in service for approximately six years. Metallographic examination of ring sections removed front the piping revealed a normal microstructure consisting of pearlite and ferrite. However, the internal surface on the thicker regions of the rings exhibited significant deposit buildup, where the thinned regions showed none. No significant corrosion or pitting was observed on either the internal or external surface of the piping. The lack of internal deposits on the affected areas and the evidence of flow patterns indicated that the wall thinning and subsequent failure were caused by internal erosion damage. The exact cause of the erosion could not be determined by the appearance of the piping. Probable causes of the erosion include an excessively high velocity flow through the piping, extremely turbulent flow, and/or intrusions (weld backing rings or weld bead protrusions) on the internal surface of the pipes. Increasing the pipe diameter and decreasing the intrusions on the internal surface would help to eliminate the problem.
Failure of Aircraft Target Towing Cables
Authors: Smith G.D.W. , Easterling K.E.
Published: May 2019

Over a period of 2 or 3 years, 40 to 50 premature failures of drawn high-tensile, pearlitic high-carbon (0.8 wt% C) steel wires used as cables for towing targets behind aircraft occurred. Six service failures were examined in detail. Four types of failure characteristics were noted. A close examination of wire that had been flown several times without failure was also made, and dynamic tests were conducted to investigate the fracture characteristics of wire subjected to dynamic loading. It was concluded that dynamic shock loading transmitted by the target during unsteady flight conditions was the major cause of failure. Recommendations emphasized the need for a suitable shock absorber to be fitted at the constant-tensioning device of the winch system.
Failure of Trailer Kingpins Caused by Overheating During Forging
Authors: Maccagno T.M. , Jonas J.J. , Yue S. , Thompson J.G.
Published: May 2019

To forged AISI 4140 steel trailer kingpins fractured after 4 to 6 months of service. Fractographic and metallographic examination revealed that cracks were present in the spool-flange shoulder region of the defective kingpins prior to installation on the trailers. The cracks grew and coalesced during service. Consideration of the manufacturing process suggested that the cracks were the result of overheating of the kingpin blanks prior to forging, which was exacerbated during forging by deformation heating in the highly-strained region. This view was supported by results of two types of tensile tests conducted near the incipient melting temperature at the grain boundaries. All kingpins made by the supplier of the fractured ones were ultrasonically inspected and six more anticipated to fail were found. It was recommended that the heating of forging blanks be more carefully controlled, especially with respect to the accuracy of the optical pyrometer temperature readout. Also, procedures must be developed such that forging blanks that trigger the over-temperature alarm are reliably and permanently removed from the production line.
Failure of a Sprocket Drive Wheel in a Tracked All-Terrain Vehicle
Authors: Pollard W.A.
Published: May 2019

A sand-cast LM6M aluminum alloy sprocket drive wheel in an all-terrain vehicle failed. Extensive cracking had occurred around each of the six bolt holes in the wheel. Evidence of considerable deformation in this area was also noted. Examination indicated that the part failed because of gross overload. Use of an alloy with a much higher yield strength and improvement in design were recommended.
Fracture of a Train Wheel Due to Thermally Induced Fatigue and Residual Stress
Authors: D'Antonio Carmine
Published: May 2019

An ASTM A 504 carbon steel railway car wheel that was used on a train in a metropolitan railway system failed during service, causing derailment. The wheel was completely fractured from rim to hub. Macrofractography of the fracture surface showed road grime, indicating that the crack had existed for a considerable time prior to derailment and initiated in the flange. Failure propagated from the flange across the rim and down the plate to the bore of the hub. Two zones that exhibited definite signs of heating were observed. The fracture initiation site was typical of fatigue fracture. No defects were found that could have contributed to failure. The wheel conformed to the chemical, microstructural, and hardness requirements for class A wheels. Failure was attributed to repeated severe heating and cooling of the rim and flange due to brake locking or misapplication of the hand brake. It was recommended that the brake system on the car be examined and replaced if necessary.
In-Service Failure of SAE Grade 8.1 Wheel Studs
Authors: Shipley Roch J. , Bouldin Peter C. , Holmes Edward W.
Published: May 2019

Failure of carbon-manganese steel wheel studs caused by improper tightening of the inner wheel nuts resulted in separation of a dual wheel assembly on a heavy truck. The benchmark pattern observed on the fracture surfaces of the studs evidenced fatigue cracks emanating from multiple origins around the circumference. There was no indication that any microstructural characteristics of the material contributed to the failure. Inclusions that were present were small and relatively few in number. Failure to check the torque of the inner wheel nuts as per the manufacturer's recommendation caused the inner wheel nuts to loosen during break-in and lose the required clamping force. The development and promotion of educational programs on proper wheel tightening procedures was recommended.
Acidic Pitting in Waterwall Tubing
Authors: Weiss Wendy L. , Jones John C.
Published: May 2019

Severe pitting was found on the internal surfaces of SA-210 Grade C waterwall tubing of a coal-fired boiler at a cogeneration facility. Metallographic examination showed the pits to be elliptical, having an undercut morphology with supersurface extensions,. a type of pitting characteristic of acidic attack. Energy-dispersive X-ray spectroscope revealed the presence of chlorine in the pit deposits, indicating that the pitting was promoted by underdeposit chloride attack. The presence of copper in deposits on the internal surface of the tubing may have acted as a secondary factor. Acidic conditions may have formed during a low-pH excursion that reportedly occurred several years prior. To prevent future failures, severely damaged tubing must be replaced. Internal deposit buildup must be removed by chemical cleaning to prevent further pitting. Water quality needs continued monitoring and maintenance to ensure that another low-pH excursion does not occur.
Cracking in a Reducing Pipe From a Pressurized Water Reactor
Authors: Czajkowski Carl J.
Published: May 2019

Three ASME SA106 grade B carbon steel feed water piping reducers from a pressurized water reactor showed indications of flaws near welds during ultrasonic testing. Further examination and testing indicated that the cracks resulted from a low-cycle corrosion fatigue phenomenon.
Failure of a Reactor Tube
Authors: Ciulik J.
Published: May 2019

A low-carbon steel (St35.8) tube in a phthalic anhydride reactor system failed. Visual and stereomicroscopic examination of fracture surfaces revealed heavy oxide/deposits on the outer surface of the tube, tube wall thinning in the area of the fracture, and discolorations and oxides/deposits on the inner surface. Cross sections from the fracture surface were metallographically examined, and the deposits were analyzed. It was determined that the tube had thinned from the inner surface because of a localized overheating condition (probably resulting from a runaway chemical reaction within the tube) and then fractured, which allowed molten salt to flow into the tube.
Steam Superheater 800H Tube Failure
Authors: Franz Edward J.
Published: May 2019

An SB407 alloy 800H tube failed at a 100 deg bend shortly after startup of a new steam superheater. Three bends failed and one bend remote from the failure area was examined. Visual examination showed that the fracture started on the outside surface along the inside radius of the bend and propagated in a brittle, intergranular fashion. Chemical analysis revealed that lead contamination was a significant factor in the failure and phosphorus may have contributed. The localized nature of the cracks and minimum secondary cracking suggested a distinct, synergistic effect of applied tensile stress with the contamination. Stress analysis found that stress alone was not enough to cause failure; however the operating stresses in the 100 deg bends were higher than at most other locations in the superheater Reduced creep ductility may be another possible cause of failure. Remedial actions included reducing the tube temperature, replacing the Schedule 40 100 deg bends with Schedule 80 pipe, and solution annealing the pipe after bending.
Stress-Corrosion Cracking in a Downcomer Expansion Joint
Authors: Bowman Ralph D.
Published: May 2019

A type 321 stainless steel downcomer expansion joint that handled process gases was found to be leaking approximately 2 to 3 weeks after installation. The expansion joint was the second such coupling placed in the plant after failure of the original bellows. The failed joint was disassembled and examined to determine the cause of failure. Energy-dispersive x-ray analysis revealed significant peaks for chlorine and phosphorus, indicating failure by chloride stress-corrosion cracking (SCC). Cracks in the liner and bellows exhibited a branched pattern also typical of SCC. Cracks through the inner liner initiated on the outer surface of the liner and propagated inward, whereas cracks in the bellows originated on the inner surface and propagated outward. Stress-corrosion cracking of the assembly was caused by chloride contaminants trapped inside the bellows following hydrostatic testing. Checking the test fluid for chloride and removing all fluids after hydrostatic testing were recommended to prevent further failure.
Failure of a Service Water Pump Shaft
Authors: Shaikh Hasan , Khatak H.S. , Gnanamoorthy J.B.
Published: May 2019

A service water pump in a nuclear reactor failed when its shaft gave way. The fracture originated in the threaded portion of the sleeve nut on the drive-end side of the shaft. Results of the failure analysis showed that the cracking initiated at the thread root as a result of corrosion fatigue. Crack propagation occurred either by corrosion or mechanical fatigue. Evidence was found indicating high rotary bending stresses on the shaft during operation. The nonstandard composition of the En 8 steel used in the shaft and irregular maintenance reduced the life of the shaft. Recommendations included use of a case-hardened En 8 steel with the correct composition and regular maintenance of the pump.
Phytochemistry and Antioxydante Activity ofStevia rebaudiana
Authors: Kharchouf S. , Bouchador A. , Drioiche A. , Khiya Z. , El Hilali F. , Zair T.
Published: May 2019

Stevia rebaudianais a perennial shrub belonging to the Asteraceae family. Recently, it has been introduced to Morocco from its native Paraguay; its molecules have a sweetening power that is about 300 times sweeter than sucrose. This characteristic makes of this plant a considerable natural noncalorific sweetener in case of hypoglycemic or low carbohydrate diet. This important interest has prompted us to make further studies on this plant. The objective of this work is to show the value ofStevia rebaudianagrown in the Larache region of Morocco by the chemical characterization and evaluation of the antioxidant activity of its extracts. A phytochemical screening was carried out to highlight the qualitative composition of secondary metabolites. This analysis showed the presence of flavonoids, tannins, oses and holosides, sterols, triterpenes, and free anthraquinones. However, the absence of alkaloids and reducing compounds has been observed. In addition, extraction of the total polyphenols was carried out by maceration using a 70% methanol–water mixture. The yield is of the order of 28.6%. Subsequently, fractionation of the crude extract was carried out by successively using three organic solvents of different polarities: chloroform, ethyl acetate, andn-butanol. Polyphenol dosage with Folin-Ciocalteu’s reagent showed that ethyl acetate fraction is richer in phenolic compounds (26.4%) than the other fractions. Flavonoids dosage with aluminum trichloride showed the richness of this plant in these compounds. The antioxidant activity of different fractions was evaluated by 2,2-diphenyl-1-picrylhydrazyl-free radical scavenging method and ferric reducing/antioxidant power method; the values of the 50% inhibitory concentrations (IC50) were determined graphically. It is equal to 0.32 mg/ml for the ethyl acetate fraction, compared to 0.08 mg/ml for the ascorbic acid used as a reference. In this study, we have shown thatStevia rebaudianais very rich in phenolic compounds and possesses a very important antioxidant power.