bluuebunny/crossref_metadata_2025 huggingface dataset:
miR-144/451 Promote Cell Proliferation via Targeting PTEN/AKT Pathway in Insulinomas
Authors: Jiang Xiuli , Shan Aijing , Su Yutong , Cheng Yulong , Gu Weiqiong , Wang Weiqing , Ning Guang , Cao Yanan
Published: April 2015

Insulinoma is the main type of functional pancreatic neuroendocrine tumors. The functional microRNAs (miRNAs) regulating tumor growth and progression in insulinomas are still unknown. We conducted the miRNA expression profile analysis using miRNA quantitative RT-PCR array and identified 114 differentially expressed miRNAs in human insulinomas compared with normal pancreatic islets. Forty-one differentially expressed miRNAs belonged to 7 miRNA families, and 28 miRNAs in 3 of the families localized in the epigenetically regulated imprinted chromosome 14q32 region. We validated the most significant differentially expressed miRNA cluster miR-144/451 in another 8 human normal islet samples and 25 insulinomas. Our data showed that the overexpression of miR-144/451 in mouse pancreatic β-cells promoted cell proliferation by targeting the β-cell regulator phosphatase and tensin homolog deleted on chromosome ten/v-akt murine thymoma viral oncogene homolog pathway and cyclin-dependent kinase inhibitor 2D. Our findings highlight the importance of functional miRNAs in insulinomas.
Developmental Programming: Prenatal and Postnatal Androgen Antagonist and Insulin Sensitizer Interventions Prevent Advancement of Puberty and Improve LH Surge Dynamics in Prenatal Testosterone-Treated Sheep
Authors: Padmanabhan Vasantha , Veiga-Lopez Almudena , Herkimer Carol , Abi Salloum Bachir , Moeller Jacob , Beckett Evan , Sreedharan Rohit
Published: April 2015

Prenatal T excess induces maternal hyperinsulinemia, early puberty, and reproductive/metabolic defects in the female similar to those seen in women with polycystic ovary syndrome. This study addressed the organizational/activational role of androgens and insulin in programming pubertal advancement and periovulatory LH surge defects. Treatment groups included the following: 1) control; 2) prenatal T; 3) prenatal T plus prenatal androgen antagonist, flutamide; 4) prenatal T plus prenatal insulin sensitizer, rosiglitazone; 5) prenatal T and postnatal flutamide; 6) prenatal T and postnatal rosiglitazone; and 7) prenatal T and postnatal metformin. Prenatal treatments spanned 30–90 days of gestation and postnatal treatments began at approximately 8 weeks of age and continued throughout. Blood samples were taken twice weekly, beginning at approximately 12 weeks of age to time puberty. Two-hour samples after the synchronization with prostaglandin F2α were taken for 120 hours to characterize LH surge dynamics at 7 and 19 months of age. Prenatal T females entered puberty earlier than controls, and all interventions prevented this advancement. Prenatal T reduced the percentage of animals having LH surge, and females that presented LH surge exhibited delayed timing and dampened amplitude of the LH surge. Prenatal androgen antagonist, but not other interventions, restored LH surges without normalizing the timing of the surge. Normalization of pubertal timing with prenatal/postnatal androgen antagonist and insulin sensitizer interventions suggests that pubertal advancement is programmed by androgenic actions of T involving insulin as a mediary. Restoration of LH surges by cotreatment with androgen antagonist supports androgenic programming at the organizational level.
Improvements in Bone Density and Structure during Anti-TNF-α Therapy in Pediatric Crohn's Disease
Authors: Griffin Lindsay M. , Thayu Meena , Baldassano Robert N. , DeBoer Mark D. , Zemel Babette S. , Denburg Michelle R. , Denson Lee A. , Shults Justine , Herskovitz Rita , Long Jin , Leonard Mary B.
Published: April 2015

Context:

Pediatric Crohn's Disease (CD) is associated with deficits in trabecular bone mineral density (BMD) and cortical structure, potentially related to TNF-α effects to decrease bone formation and promote bone resorption.

Objective:

This study aimed to examine changes in bone density and structure in children and adolescents with CD following initiation of anti-TNF-α therapy.

Design and Participants:

Participants (n = 74; age 5–21 years) with CD completed a 12-month prospective cohort study.

Main Outcome Measures:

Tibia peripheral quantitative computed tomography scans were obtained at initiation of anti-TNF-α therapy and 12 months later. Musculoskeletal outcomes were expressed as sex-and race-specific z scores relative to age, based on >650 reference participants.

Results:

At baseline, CD participants had lower height, trabecular BMD, cortical area (due to smaller periosteal and larger endocortical circumferences), and muscle area z scores, compared with reference participants (all P < .01). Pediatric CD activity index decreased during the 10-week induction (P < .001), in association with subsequent gains in height, trabecular BMD, cortical area (due to recovery of endocortical bone), and muscle area z scores over 12 months (height P < .05; others P < .001). Bone-specific alkaline phosphatase levels, a biomarker of bone formation, increased a median of 75% (P < .001) during induction with associated 12-month improvements in trabecular BMD and cortical area z scores (both P < .001). Younger age was associated with greater increases in trabecular BMD z scores (P < .001) and greater linear growth with greater recovery of cortical area (P < .001).

Conclusions:

Anti-TNF-α therapy was associated with improvements in trabecular BMD and cortical structure. Improvements were greater in younger and growing participants, suggesting a window of opportunity for treatment of bone deficits.
Sperm-inherited organelle clearance inC. elegansrelies on LC3-dependent autophagosome targeting to the pericentrosomal area
Authors: Djeddi Abderazak , Al Rawi Sara , Deuve Jane Lynda , Perrois Charlene , Liu Yu-Yu , Russeau Marion , Sachse Martin , Galy Vincent
Published: April 2015

Macroautophagic degradation of sperm-inherited organelles prevents paternal mitochondrial DNA transmission in C. elegans. The recruitment of autophagy markers around sperm mitochondria has also been observed in mouse and fly embryos but their role in degradation is debated. Both worm Atg8 ubiquitin-like proteins, LGG-1/GABARAP and LGG-2/LC3, are recruited around sperm organelles after fertilization. Whereas LGG-1 depletion affects autophagosome function, stabilizes the substrates and is lethal, we demonstrate that LGG-2 is dispensable for autophagosome formation but participates in their microtubule-dependent transport toward the pericentrosomal area prior to acidification. In the absence of LGG-2, autophagosomes and their substrates remain clustered at the cell cortex, away from the centrosomes and their associated lysosomes. Thus, the clearance of sperm organelles is delayed and their segregation between blastomeres prevented. This allowed us to reveal a role of the RAB-5/RAB-7 GTPases in autophagosome formation. In conclusion, the major contribution of LGG-2 in sperm-inherited organelle clearance resides in its capacity to mediate the retrograde transport of autophagosomes rather than their fusion with acidic compartments: a potential key function of LC3 in controlling the fate of sperm mitochondria in other species.
Mechanobiology of myofibroblast adhesion in fibrotic cardiac disease
Authors: Schroer Alison K. , Merryman W. David
Published: April 2015

Fibrotic cardiac disease, a leading cause of death worldwide, manifests as substantial loss of function following maladaptive tissue remodeling. Fibrosis can affect both the heart valves and the myocardium and is characterized by the activation of fibroblasts and accumulation of extracellular matrix. Valvular interstitial cells and cardiac fibroblasts, the cell types responsible for maintenance of cardiac extracellular matrix, are sensitive to changing mechanical environments, and their ability to sense and respond to mechanical forces determines both normal development and the progression of disease. Recent studies have uncovered specific adhesion proteins and mechano-sensitive signaling pathways that contribute to the progression of fibrosis. Integrins form adhesions with the extracellular matrix, and respond to changes in substrate stiffness and extracellular matrix composition. Cadherins mechanically link neighboring cells and are likely to contribute to fibrotic disease propagation. Finally, transition to the active myofibroblast phenotype leads to maladaptive tissue remodeling and enhanced mechanotransductive signaling, forming a positive feedback loop that contributes to heart failure. This Commentary summarizes recent findings on the role of mechanotransduction through integrins and cadherins to perpetuate mechanically induced differentiation and fibrosis in the context of cardiac disease.
Innovation, Trade, and Finance
Authors: Egger Peter , Keuschnigg Christian
Published: April 2015

Heterogeneous firms invest in R&D and expansion investment. Venture capital specializes in R&D financing where problems are largest. Marginal firms get funded by venture capital, while firms with larger debt capacity obtain cheaper bank financing. In the late-stage, cash-rich firms invest at an optimal scale, while cash-poor firms are restricted. A country's financial and institutional development determines entry and expansion of firms and their comparative advantage in producing innovative goods. We illustrate how tariffs, R&D subsidies, institutional reform and venture capital improve access to capital, expand innovative industries, boost national welfare and may result in ambiguous international welfare spillovers. (JEL D21, F11, F13, G24, G32, O32)
Preferences over Equality in the Presence of Costly Income Sorting
Authors: Levy Gilat , Razin Ronny
Published: April 2015

We analyze preferences over redistribution in societies with costly (positive) sorting according to income. We identify a new motivation for redistribution, where individuals support taxation in order to reduce the incentives to sort. We characterize a simple condition over income distributions which implies that even relatively rich voters—with income above the mean—will prefer full equality (and thus no sorting) to societies with costly sorting. We show that the condition is satisfied for relatively equal income distributions. We also relate the condition to several statistical properties which are satisfied by a large family of distribution functions. (JEL D31, D63, H23)
State Censorship
Authors: Shadmehr Mehdi , Bernhardt Dan
Published: April 2015

We characterize a ruler's decision of whether to censor media reports that convey information to citizens who decide whether to revolt. We find: (i) a ruler gains (his ex ante expected payoff increases) by committing to censoring slightly less than he does in equilibrium: his equilibrium calculations ignore that censoring less causes citizens to update more positively following no news; (ii) a ruler gains from higher censorship costs if and only if censorship costs exceed a critical threshold; (iii) a bad ruler prefers a very strong media to a very weak one, but a good ruler prefers the opposite. (JEL D72, D74, D83)
Formal versus Informal Monitoring in Teams
Authors: Gershkov Alex , Winter Eyal
Published: April 2015

In this paper we analyze a principal's optimal monitoring strategies in a team environment. In doing so we study the interaction between formal monitoring and informal (peer) monitoring. We show that if the technology satisfies complementarity, peer monitoring substitutes for the principal's monitoring. However, if the technology satisfies substitution, the principal's optimal monitoring is independent of the peer monitoring. We also show that if the technology satisfies complementarity, then the principal in the optimal contracts will monitor more closely than in the case of substitution. (JEL D23, D82, M54)
School leadership for equity and learning and the question of school autonomy
Authors: Hatzopoulos Pavlos , Kollias Andreas , Kikis-Papadakis Kathy
Published: April 2015

Artikkel põhineb koolijuhtimise Euroopa võrgustiku (EPNoSL) raames tehtud tööl, eelkõige 21 Euroopa riigi koolijuhtimise strateegiate süvauuringul ja aruteludel, mis toimuvad EPNoSLi veebiseminaridel, riikide õpikodades ja vastastikuse õppe üritustel, millest võtavad osa mitmes ELi riigis koolijuhtimisega seotud huvirühmad (sh Euroopa, riikliku ja kohaliku tasandi poliitikakujundajad, koolijuhid, õpetajad ja teised haridustöötajad, õppejõud, lapsevanemad ja õpilased). EPNoSL on Euroopas tegutsevast 42 institutsioonist koosnev võrgustik, mille eesmärk on parandada Euroopa koolide juhtimist nii poliitilisel kui ka praktilisel tasandil. Artiklis käsitletakse koolide autonoomia küsimust Euroopa koolijuhtimise strateegiate kujundamise kontekstis. Koolide autonoomiat peetakse tervikliku koolijuhtimise poliitika väljatöötamise oluliseks eeltingimuseks. Artikkel tugineb kõnealuse projekti raames välja töötatud laiaulatuslikule koolijuhtimise strateegia kujundamise raamistikule ja sellel on kaks põhieesmärki. Esiteks püütakse artiklis näidata, et selle asemel et otsida koolide autonoomia puhul ühte, kõigile sobivat lahendust, tuleks keskenduda konkreetset olukorda arvestavale strateegiale, mille eesmärk on saavutada kindlaksmääratud õpitulemused ja võrdsed võimalused. Teiseks on artiklis kirjeldatud seitset koolide autonoomia põhisuunda, mida on võimalik kohandada Euroopa eripalgeliste haridussüsteemidega.
 Full text
School leadership for equity and learning and the question of school autonomy
Authors: Hatzopoulos Pavlos , Kollias Andreas , Kikis-Papadakis Kathy
Published: April 2015

The article draws from the work conducted in the context of the European Policy Network on School Leadership (EPNoSL). In particular, it is based on an in-depth review of school leadership policies in 21 European countries and the discourse that is taking place in EPNoSL’s webinars, national workshops and peer learning activities organised in several EU countries with the participation of a variety of school leadership stakeholders (including policy makers at European, national, and local levels, school leaders, teachers and other professionals, academics, researchers, parents and students). EPNoSL is a network of 42 European institutions that aims at improving policy on, and practice in, school leadership in Europe. The article discusses the question of school autonomy in the context of school leadership policy development in Europe. School autonomy is considered as a critical precondition for the development of comprehensive school leadership policies. Based on the comprehensive framework of school leadership policy development that has been developed in the context of this project, the article undertakes two main tasks. Firstly, it attempts to show that instead of searching for universal solutions on the question of school autonomy, it is important to reflect on context-specific policies on autonomy that aim at the attainment of concrete learning and equity goals. Secondly, it specifies seven general directions for policies on school autonomy that are adaptive to the divergent experiences of European education systems.
Methodological challenges and choices when identifying EU related training needs of Estonian public service
Authors: Veebel Viljar , Kulu Liina , Hurt Ulrika
Published: April 2015

Artiklis analüüsitakse Eesti avaliku sektori töötajate koolitusvajaduse hindamisega seotud metodoloogilisi sõlmküsimusi, tuginedes aastatel 2002–2013 ametnike ja poliitikute seas korraldatud Euroopa Liidu alase koolitusvajaduse uuringutele. Sarnaste uuringute kaudu koolitusvajaduse kindlaksmääramisel on keskse tähtsusega kolm aspekti. Esiteks, uuring peaks olema keskendunud just koolitusvajaduse, mitte aga igapäevatöös oluliste teemade, koolitussoovide vms väljaselgitamisele. Teiseks, uuringut ette valmistavas faasis tuleb välistada tulemuste kalibreerimine, kus vastajaid suunatakse nn ohtlikele küsimustele vastama uuringu tellija jaoks sobival viisil. Kolmandaks on soovitatav peale küsitluspõhise uurimismeetodi kasutada ka mõõdetavat teadmiste kontrolli vormi (nt testi), mis võimaldab objektiivselt tuvastada vastaja kalduvust teadmisi ja oskusi üle- või alahinnata (nn Dunningi-Krugeri efekt).
 Summary
Administrative traditions and citizen participation in public policy: a comparative study of France, Germany, the UK and Norway
Authors: Huxley Katy , Andrews Rhys , Downe James , Guarneros-Meza Valeria
Published: April 2015

The participation of citizens in public policy-making has become a key aim for national and supranational institutions across Europe, but the relative importance policy-makers actually accord citizen participation arguably varies due to the alternative administrative traditions within different countries. Using data drawn from a large-scale survey of senior public managers in France, Germany, the United Kingdom (UK) and Norway, we find support for the idea that administrative tradition influences the participation of citizens in public policy. We also identify key institutional factors determining the importance of citizen participation. Theoretical and practical implications of the findings are discussed.
From the borders to centre stage: Photographic self-portraiture
Authors: Kalpaxi Elisavet
Published: April 2015

This article examines photographic self-portraiture and investigates what happens when the genre’s proximity to conceptual borders – between the centre and the margins, self and other, normal and deviant behaviour, consciousness and unconsciousness – are crossed. Drawing on psychoanalytic and semiotic theories, and the history of the self-portrait, this article investigates the negativity ascribed to self-portraiture, its association with identity politics and social media, and problems of reference arising in contemporary artworks. The article starts out from the premise that the objectification of one’s body image is inherently linked to narcissism. This idea is useful for understanding the meaning of the photo-album/photo-diary, the therapeutic aspects of self-portraiture, and the rhetoric applied to images produced to bring visibility to marginalized and under-represented groups, which also serve to challenge the art establishment. However, the prioritization of art as a context for photography, the popularity of the genre, and the changing ideas related to definitions of ‘the centre’ in these contexts, demand that the conceptual character of the representation of selfhoods be redefined.
Fernando I y la sacralización de la Reconquista
Authors: Ayala Martínez Carlos de
Published: April 2015

El siglo XI experimenta un cambio en el proceso de legitimación de la reconquista. La guerra contra el islam no es ya la lucha por la supervivencia de períodos anteriores, sino una exigencia de la voluntad política de expansión territorial. Este hecho exigía todo un incremento de avales justificadores que convergen en una misma dirección: la mayor sacralización de la reconquista. El presente estudio pretende analizar este proceso durante el reinado de Fernando I de León y Castilla.
Predicación de cruzada y yihad en la Península Ibérica: una propuesta comparativa
Authors: Rodríguez García José Manuel
Published: April 2015

El presente trabajo pretende realizar una primera aproximación a una temática que consideramos deficitaria en nuestra historiografía, como es el estudio de la predicación de cruzada y yihad, tanto en sus aspectos formales como de contenido. Además tiene la intención de presentar una visión comparativa, desde los campos musulmán y cristiano, a dicha problemática. Se presentan una serie de líneas de investigación, bases y principios que puedan ser tenidos en cuenta para nuevos y necesarios estudios.
Cultura visual e iconografía de la Reconquista: imágenes de poder y cruzada
Authors: Palacios Ontalva J. Santiago
Published: April 2015

El propósito de este trabajo consiste en ofrecer una síntesis en torno al valor de las imágenes como elementos capaces de transmitir mensajes culturales y políticos complejos dentro de la sociedad medieval, y más concretamente en relación a la génesis, desarrollo y difusión de algunos conceptos asociados a las ideas de cruzada y reconquista en el ámbito hispano. Para ello, se analizan los principales elementos que participan en dicho proceso de comunicación (emisor, receptor, mensaje, código y canal etc.), un intercambio de información que, durante la Edad Media, estuvo fundamentado en la imagen y los símbolos más que en los textos o la palabra, y que es posible analizar a partir de los numerosos testimonios artísticos y plásticos que conservamos de aquel periodo. La principal conclusión que se desprende del estudio de este proceso de comunicación, incide en la importancia que los mensajes visuales tuvieron, dentro de una sociedad prácticamente ágrafa, en la transmisión de una ideología combativa contra el Islam andalusí basada en argumentos religiosos pero también culturales, políticos e históricos.
Incidencias y complicaciones del acceso intravenoso en la Unidad de Oncología del Hospital Vithas Perpetuo Socorro de Alicante
Authors: Corbí Rico Daniel , Reig Aliaga Eva , Esplá Fernández Ana , Ferrando Ramírez Juan Manuel
Published: April 2015

Introducción: En las unidades de hospital de día se administran los tratamientos oncohematológicos, fluidos, fármacos, productos sanguíneos y soporte nutricional. Objetivo: Conocer las incidencias y complicaciones de nuestros pacientes relacionadas con la administración del tratamiento en el hospital de día. Material y métodos: Estudio descriptivo prospectivo. Se ha diseñado la hoja del Anexo 1 adaptada por los autores para la recogida de datos. Los datos se han recogido en el hospital de día por la enfermera que administra el tratamiento. Resultados: Se han estudiado 550 pacientes, 209 eran portadores de gripper y a 341 se les canalizó una vía periférica. Las complicaciones totales que hemos registrado son: 7 extravasaciones con suero fisiológico, siempre en tratamientos de más de un día; 7 cambios de vías de acceso por obstrucciones o hematomas; 1 cambio de acceso por prurito y prevención de flebitis. Sólo hemos tenido 1 extravasación con oxaliplatino localizada en el dorso de la mano derecha, en la que aplicamos calor durante 30 minutos, aspiramos todo lo que se pudo y evitamos que se complicara. Conclusiones: Hemos obtenido un resultado muy aceptable en el límite inferior del rango de complicaciones. La prestación de los cuidados y el seguimiento por parte del mismo profesional es de vital importancia en la unidad del hospital de día.
Proceso de atención de enfermería en un paciente geriátrico
Authors: Alba Martín Raquel , Armenteros Berral Marina del Mar , Barroso Estévez Elena , Fernández Córdoba Ana María , Zafra Sánchez María Teresa
Published: April 2015

Presentamos caso de varón de 81 años ingresado en una Residencia de ancianos, en el que elaboraremos un plan de cuidados estandarizados, con el objetivo de mantener su independencia funcional, mejorar su calidad de vida, disminuir la mortalidad y aumentar la esperanza de vida, proporcionando una atención individualizada al anciano y a su entorno. Realizaremos una valoración geriátrica integral y con ello valoraremos, mediante la taxonomía enfermera NANDA, NIC, NOC y la Escala Nutricional (MNA), sus necesidades alteradas siguiendo el modelo de Virginia Henderson. Con la presentación de este caso, pretendemos dar una serie de recomendaciones para la conservación de su salud e independencia funcional, por ser los aspectos más importantes de la promoción de la salud en los adultos de edad avanzada.
QUALIDADE MICROBIOLÓGICA DA ÁGUA UTILIZADA EM PROPRIEDADES LEITEIRAS
Authors: Rangel Adriano Henrique do Nascimento , Freire Rayssa Maria Bezerril , Borba Luís Henrique Fernandes , Lima Júnior Dorgival Morais de , Novaes Luciano Patto
Published: April 2015

Objetivou-se avaliar a qualidade microbiológica de amostras de água de poço utilizada na ordenha, além de verificar sua influência na contagem bacteriana total (CBT) do leite obtido em propriedades no estado do Rio Grande do Norte. Amostras de 1.000 mL de água do poço e da água utilizada na ordenha foram coletadas em recipientes estéreis e realizadas análises de coliformes totais e termotolerantes, pelo método de membrana filtrante. Amostras da água do poço apresentaram valores de 21.250 UFC/100 mL para coliformes totais e 12.269 UFC/100 mL para coliformes termotolerantes e as amostras da água da ordenha apresentaram valores de 5.520 UFC/100 mL para coliformes totais e 3.483 UFC/100 mL para coliformes termotolerantes. A detecção de coliformes nas amostras analisadas afetou a qualidade microbiológica do leite avaliada por meio da CBT. Constatou-se que a qualidade microbiológica da água utilizada nas propriedades leiteiras apresenta-se fora do preconizado pelo Ministério da Saúde para uso na higienização dos equipamentos e consumo pelos animais e seres humanos, quanto aos padrões de potabilidade.
ENUMERAÇÃO DE MICRORGANISMOS PSICROTRÓFICOS E TERMODÚRICOS PSICROTROFICOS DE LEITE: COMPARAÇÃO DE METODOLOGIAS
Authors: Beloti Vanerli , Ribeiro Júnior José Carlos , Tamanini Ronaldo , Araújo João Paulo Andrade de , Yamada Alberto Koji , Antônio Nayara Da Silva
Published: April 2015

O objetivo do presente trabalho foi avaliar se o binômio temperatura/tempo de 21 ºC por 25 horas, já validado para enumeração de psicrotróficos em leite, apresenta viabilidade para enumeração de termodúricos psicrotróficos, comparando as contagens dos psicrotróficos e dos termodúricos psicrotróficos obtidas em cada binômio de tempo e temperatura de incubação. Foram avaliadas 28 amostras de leite cru refrigerado coletadas em tanques de caminhões transportadores na plataforma de recepção de um laticínio no norte do Paraná. Foram enumerados psicrotróficos e termodúricos psicrotróficos à 7 ºC por 10 dias e a 21 ºC por 25 horas. Para os psicrotróficos, foi observado que não houve diferença significativa das contagens comparando os dois métodos de incubação (p = 0,46), o coeficiente de correlação entre os métodos foi de 0,90 e a regressão linear considerada satisfatória. Para os termodúricos psicrotróficos, também não foi observada diferença significativa (p = 0,17) nas contagens, porém, o coeficiente de correlação entre os dois métodos foi de 0,69 e a regressão linear insatisfatória. Foi observada também maior homogeneidade na distribuição dos resultados das contagens de psicrotróficos em relação aos termodúricos psicrotróficos. Os resultados demonstram que a enumeração de microrganismos termodúricos psicrotróficos pela metodologia mais rápida não é adequada, uma vez que o coeficiente de correlação e a regressão linear dos métodos são baixos.
Processing and Properties of Distaloy Sa Sintered Alloys with Boron and Carbon
Authors: Karwan-Baczewska J.
Published: April 2015

Prealloyed iron-based powders, manufactured in Höganäs Company, are used in the automotive parts industry. The properties and life time of such sintered parts depend, first of all, on their chemical composition, the production method of the prealloyed powder as well as on the technology of their consolidation and sintering. One of simpler and conventional methods aimed at increasing the density in sintered products is the process of activated sintering, performed, for example, by adding boron as elementary boron powder. Under this research project obtained were novel sintered materials, based on prealloyed and diffusion bonded powder, type: Distaloy SA, with the following chemical composition: Fe-1.75% Ni-1.5%Cu- 0.5%Mo with carbon (0.55%; 0.75%) and boron (0.2%, 0.4% and 0.6%). Distaloy SA samples alloyed with carbon and boron were manufactured by mixing powders in a Turbula mixer, then compressed using a hydraulic press under a pressure of 600 MPa and sintered in a tube furnace at 1473 K, for a 60 minute time, in the hydrogen atmosphere. After the sintering process, there were performed density and porosity measurements as well as hardness tests and mechanical properties were carried out, too. Eventually, analyzed was the effect of boron upon density, hardness and mechanical properties of novel sintered construction parts made from Distaloy SA powder.
Fatigue Damage of Al/SiC Composites - Macroscopic and Microscopic Analysis
Authors: Rutecka A. , Kowalewski Z.L. , Makowska K. , Pietrzak K. , Dietrich L.
Published: April 2015

The results of comparative examinations of mechanical behaviour during fatigue loads and microstructure assessment before and after fatigue tests were presented. Composites of aluminium matrix and SiC reinforcement manufactured using the KoBo method were investigated. The combinations of two kinds of fatigue damage mechanisms were observed. The first one governed by cyclic plasticity and related to inelastic strain amplitude changes and the second one expressed in a form of ratcheting based on changes in mean inelastic strain. The higher SiC content the less influence of the fatigue damage mechanisms on material behaviour was observed. Attempts have been made to evaluate an appropriate fatigue damage parameter. However, it still needs further improvements.
Tem Study of Recrystallization in Ultra-Fine Grain AA3104 Alloy Processed by High-Pressure Torsion
Authors: Paul H. , Morawiec A. , Baudin T. , Czeppe T.
Published: April 2015

The effect of annealing on the microstructure and the texture development was investigated in a particle containing AA3104 aluminium alloy. The samples were processed at room temperature by high-pressure torsion (HPT) up to ten turns. The nucleation of new grains was analyzed by a transmission electron microscope equipped with a system for local orientation measurements and a heating holder.

The shear deformation induces a decrease of the grain size. After the first two turns of the HPT processing the initial structure of large grains was ‘transformed’ into a structure of fine cells/grains with the diameter of a few tens of nanometers. In the central areas of the samples the elongated shape of the cells/grains was observed up to six turns. For higher deformations, this structural inhomogeneity was totally removed and only the equiaxed grains were observed. The crystal lattice of small grains rotates in such a way that the <111> direction is parallel to the compression axis. After annealing the structure coarsened. Nevertheless, after primary recrystallization, the structure was still composed of relatively fine and equiaxed grains of a similar size. In most of the observed cases the size of the recrystallized grains in the areas close to and far from the large second phase particles was similar. The recrystallization leads to the creation of new texture components. The new grain orientations lost the positions typically observed in the deformed state and showed the tendency for the coincidence of the <100> crystallographic directions with the compression axis.
The Study of the Impact of Surface Preparation Methods of Inconel 625 and 718 Nickel-Base Alloys on Wettability by BNi-2 and BNi-3 Brazing Filler Metals
Authors: Lankiewicz K. , Baranowski M. , Babul T. , Kowalski S.
Published: April 2015

The article discusses the impact of surface preparation method of Inconel 625 and 718 nickel-base alloys in the form of sheets on wettability of the surface. The results of the investigations of surface preparation method (such as nicro-blasting, nickel plating, etching, degreasing, abrasive blasting with grit 120 and 220 and manually grinding with grit 120 and 240) on spreading of BNi-2 and BNi-3 brazing filler metals, widely used in the aerospace industry in high temperature vacuum brazing processes, are presented. Technological parameters of vacuum brazing process are shown. The macro- and microscopic analysis have shown that nicro-blasting does not bring any benefits of wettability of the alloys investigated.
The Influence of Strontium on the Microstructure of Cast Magnesium Alloys Containing Aluminum and Calcium
Authors: Rzychoń T. , Dybowski B. , Kiełbus A.
Published: April 2015

The structure of Mg-9Al-2Ca-xSr alloys is composed of a-Mg grains and the Al2Ca and Al4 Sr phases in the interdendritic areas. These phases are formed as a result of eutectic reactions. Globular particles of the Al8Mn5 phase are observed within the interior of the grains. The addition of strontium to Mg-9Al-2Ca-0.4Mn alloys causes the formation of the Al4Sr phase and increase of its volume fraction with increasing strontium levels. Moreover, increase of the strontium amount causes a decrease of aluminum content in the a-Mg solid solution.
Empirical Formulae for The Calculation of Austenite Supercooled Transformation Temperatures
Authors: Trzaska J.
Published: April 2015

The paper presents empirical formulae for the calculation of austenite supercooled transformation temperatures, basing on the chemical composition, austenitising temperature and cooling rate. The multiple regression method was used. Four equations were established allowing to calculate temperature of the start area of ferrite, perlite, bainite and martensite at the given cooling rate. The calculation results obtained do not allow to determine the cooling rate range of ferritic, pearlitic, bainitic and martensite transformations. Classifiers based on logistic regression or neural network were established to solve this problem.
Welding of Prosthetic Alloys
Authors: Wojciechowska M. , Wołowiec E. , Klimek L.
Published: April 2015

This paper presents the techniques of joining metal denture elements, used in prosthetic dentistry: the traditional soldering technique with a gas burner and a new technique of welding with a laser beam; the aim of the study was to make a comparative assessment of the quality of the joints in view of the possibility of applying them in prosthetic structures. Fractographic examinations were conducted along with tensile strength and impact strength tests, and the quality of the joints was assessed compared to the solid metal. The experiments have shown that the metal elements used to make dentures, joined by the technique which employs a laser beam, have better strength properties than those achieved with a gas burner.
Comparison of Properties of Polymer Composite Materials Reinforced with Carbon Nanotubes
Authors: Zygoń P. , Gwoździk M. , Peszke J. , Nitkiewicz Z.
Published: April 2015

Carbon nanotubes because of their high mechanical, optical or electrical properties, have found use as semiconducting materials constituting the reinforcing phase in composite materials. The paper presents the results of the studies on the mechanical properties of polymer composites reinforced with carbon nanotubes (CNT). Three-point bending tests were carried out on the composites. The density of each obtained composite was determined as well as the surface roughness and the resistivity at room temperature.

Moreover the surface studies on an atomic forces microscope (AFM) and X-ray studies (phase composition analysis, crystallite sizes determination) were carried out on such composites. Measurements of the surface topography using the Tapping Mode method were performed, acquiring the data on the height and on the phase imaging. The change of intensity, of crystallite size and of half-value width of main reflections originating from carbon for composites have been determined using the X-ray analysis.

Carbon nanotubes constituting the reinforcement for a polymer composite improve the mechanical properties and con-ductivity of the composite.
The Use of Barium and Calcium Alloys in the Ladle Furnace Treatment of Selected Grades of Continuously Cast Steels
Authors: Derda W. , Lawenda P. , Pardela P.
Published: April 2015

The subject of the paper are the results of laboratory and industrial investigations into the use of Si - Ca - Ba alloys for modifying non-metallic inclusions. Based on laboratory tests, the morphology and chemical composition of non-metallic inclusions in carbon steel were examined before and after refining with the use of the above-mentioned alloy as a refining addition. In particular tests, variable additions of the alloy were used at a constant refining time and temperature.

Comparison of the process of casting of a sequence of seven heats of the same steel grade using the stopper system in the tundish was made under industrial conditions. In these heats, additions of Si - Ca (three heats) and Si - Ca - Ba (four heats) were introduced as a non-metallic inclusion modifier in the form of core wires during the process in the ladle furnace. For the investigated heats, the contents of total oxygen and calcium were assayed in the finished steel. A significant effect of the simultaneous addition of barium and calcium on steel castability, and thus on the process of continuous casting of the investigated heats, was found.
Corrosion Resistance of High-Alloyed White Cast Iron
Authors: Kawalec M. , Krawiec H.
Published: April 2015

The paper presents the results of corrosion resistance tests carried out on high-alloyed white cast iron. Tests were performed in 0.1 M NaCl by the technique of linear voltammetry. The test material was collected from six high-vanadium cast iron melts with a variable content of carbon and vanadium, and thus with different microstructure. Studies have confirmed that the type of crystallised microstructure has a very important effect on the alloy corrosion resistance. The highest corrosion resistance showed the alloy with a ferritic matrix containing the spheroidal precipitates of vanadium carbide VC, while the lowest had the eutectic alloy with a pearlitic matrix.
Structure Analysis and Properties of Unleaded Brasses
Authors: Rzadkosz S. , Kozana J. , Garbacz-Klempka A. , Piękoś M.
Published: April 2015

The analysis of brasses regarding their microstructure, mechanical properties and ecological characteristics has been presented. The influence of characteristic alloying elements contained in the brasses and the possibilities of replacing them with other elements have been assessed. The paper contains the results of studies on the influence of chosen additional elements shaping the structure and properties of unleaded alloys based on Cu-Zn system as the matrix. The research aimed at determining the mechanism and the intensity of influence of such additives as tellurium and bismuth. The microstructures were investigated with the help of light microscopy and scanning electron microscopy with X-ray microanalysis (SEM-EDS) for determining significant changes of the properties.
Amorphous Dielectric Thin Films with Extremely Low Mechanical Loss
Authors: Liu X. , Queen D.R. , Metcalf T.H. , Karel J.E. , Hellman F.
Published: April 2015

The ubiquitous low-energy excitations are one of the universal phenomena of amorphous solids. These excitations dominate the acoustic, dielectric, and thermal properties of structurally disordered solids. One exception has been a type of hydrogenated amorphous silicon (a-Si:H) with 1 at.% H. Using low temperature elastic and thermal measurements of electron-beam evap-orated amorphous silicon (a-Si), we show that TLS can be eliminated in this system as the films become denser and more structurally ordered under certain deposition conditions. Our results demonstrate that TLS are not intrinsic to the glassy state but instead reside in low density regions of the amorphous network. This work obviates the role hydrogen was previously thought to play in removing TLS in a-Si:H and favors an ideal four-fold covalently bonded amorphous structure as the cause for the disappearance of TLS. Our result supports the notion that a-Si can be made a “perfect glass” with “crystal-like” properties, thus offering an encouraging opportunity to use it as a simple crystal dielectric alternative in applications, such as in modern quantum devices where TLS are the source of dissipation, decoherence and 1/f noise.
Internal Friction and Young's Modulus Measurements on SiO2 and Ta2O5 Films Done with an Ultra-High Q Silicon-Wafer Suspension
Authors: Granata M. , Balzarini L. , Degallaix J. , Dolique V. , Flaminio R. , Forest D. , Hofman D. , Michel C. , Pedurand R. , Pinard L. , Sassolas B. , Straniero N. , Teillon J. , Cagnoli G.
Published: April 2015

In order to study the internal friction of thin films a nodal suspension system called GeNS (Gentle Nodal Suspension) has been developed. The key features of this system are: i) the possibility to use substrates easily available like silicon wafers; ii) extremely low excess losses coming from the suspension system which allows to measure Q factors in excess of 2×108 on 3” diameter wafers; iii) reproducibility of measurements within few percent on mechanical losses and 0.01% on resonant frequencies; iv) absence of clamping; v) the capability to operate at cryogenic temperatures. Measurements at cryogenic temperatures on SiO2 and at room temperature only on Ta2O5 films deposited on silicon are presented.
Separate Kinetics of the Polar and Antiferrodistortive Order Parameters in the Antiferroelectric Transition of PbZr1-xTixO3 and the Influence of Defects
Authors: Cordero F. , Craciun F. , Trequattrini F. , Galassi C.
Published: April 2015

The transition from the rhombohedral-ferroelectric to the lower temperature orthorhombic-antiferroelectric phase in Zr-rich PZT involves two order parameters (OPs): 1) the polar OP for the displacements of the cations with respect to the O octahedra; 2) an antiferrodistortive OP responsible for tilting of the octahedra. It is shown that at Ti compositions near the morphotropic boundary with the FE phase (0.046 ≤ x ≤ 0.054), the two OPs may be almost independent of each other at cooling rates of 0.5 K/min or faster, depending on the sample history. This fact gives rise to a great variety of shapes of the curves of the elastic compliance s(T), but all of them can be fitted very well as superpositions of variously broadened steps for each of the modes involved in the transitions, including the tilt transition occurring in the untransformed FE fraction. The evolution of the s(T) curves includes enhancements up to a factor of four during aging for weeks in the region of the AFE/FE coexistence. Restiffening and reduction of the thermal hysteresis of the AFE/FE transition are recovered by heating up to 800-900 K. It is proposed that ageing is due to the clustering of relatively mobile defects, most likely O vacancies, at the domain walls in the coexisting AFE/FE phases. Such defect structures are probably at the origin of intense thermally activated relaxation processes observed above TC in the dielectric and anelastic spectra, and can be annealed out above 800 K, allowing the AFE transition to recover a fast kinetics.
Estimation of the Level of Residual Stress in Wires with a Magnetic Method
Authors: Suliga M. , Borowik L. , Chwastek K.
Published: April 2015

Residual stress present in wires after drawing process affects their magnetic properties. The paper presents a concept to estimate the level of residual stress on the basis of measurements of hysteresis loops. In order to describe the effect qualitatively the Jiles-Atherton-Sablik description is adapted. On the basis of variations in hysteresis loop shapes the average values of residual stress in wires for different single draft values are determined. It was found that the estimated average values by magnetic stresses are comparable with the results of numerical modeling and experimental studies.
Numerical Analysis of the Skew Rolling Process for Rail Axles
Authors: Pater Z. , Tomczak J. , Bulzak T.
Published: April 2015

The paper describes a new method for producing stepped rail axles. The method is based on the skew rolling process. With this method, the product is formed by three tapered rolls located every 120° on the perimeter of the billet. Positioned askew to the centerline of the billet, the rolls rotate in the same direction and with the same velocity. At the same time, they get closer together or go apart depending on the desired cross sectional reduction of an axle step. In addition, the workpiece is shifted lengthwise relative to the rolls by the translational motion of the workpiece-holding chuck. In order to verify the designed method for producing rail axles, a series of numerical simulations were performed using the Simufact. Forming v.12 simulation software. The numerical modeling enabled the determination of maps of the effective strain and temperature in the finished product as well as variations in the loads and torques during rolling. The numerical results unambiguously confirm that the skew rolling method can be applied to form parts of considerable dimensions (the modeled axles had a length of 2146 mm and their maximum diameter was 202 mm).
Theoretical and Experimental Research on Forge Rolling Process of Preforms From Magnesium Alloy AZ31
Authors: Bulzak T. , Tomczak J. , Pater Z.
Published: April 2015

This paper presents results of theoretical and experimental research works on the rolling process of a lever preform from magnesium alloy AZ31. The forge rolling process of the preform was realized in the system oval-circle. The paper focuses mainly on kinematics of material flow and proper filling of rolling impressions. Research aiming at determining possibilities of faults presence in the form of cracks, overlapping and improper filling of the impressions were also conducted. During experimental research it was noticed that material cracking took place at the moment of material clamping by rolls. Moreover, it was stated that this cracking may be the result of large shearing stresses action, appearing at the moment of material clamping by rolls. Shearing stresses values were determined on the basis of numerical calculations. Next, tools were modified in order to lower tangential stresses at the moment of material clamping by rolls. The further experimental research with modified tools confirmed the rightness of the assumptions. On the basis of conducted works on the forge rolling process of magnesium alloy AZ31, it was stated that when material is clamped by tools tangential stresses intensification should not take place.
Thermal Stability of Nanocrystalline Structure In X37CrMoV5-l Steel
Authors: Skołek E. , Marciniak S. , Świątnicki W.A.
Published: April 2015

The aim of the study was to investigate the thermal stability of the nanostructure produced in X37CrMoV5-1 tool steel by austempering heat treatment consisted of austenitization and isothermal quenching at the range of the bainitic transformation. The nanostructure was composed of bainitic ferrite plates of nanometric thickness separated by thin layers of retained austenite. It was revealed, that the annealing at the temperature higher than temperature of austempering led to formation of cementite precipitations. At the initial stage of annealing cementite precipitations occurred in the interfaces between ferritic bainite and austenite. With increasing temperature of annealing, the volume fraction and size of cementite precipitations also increased. Simultaneously fine spherical Fe7C3carbides appeared. At the highest annealing temperature the large, spherical Fe7C3carbides as well as cementite precipitates inside the ferrite grains were observed. Moreover the volume fraction of bainitic ferrite and of freshly formed martensite increased in steel as a result of retained austenite transformation during cooling down to room temperature.
Corrosion Resistance of Co-Cr-Mo Alloy Used in Dentistry
Authors: Łukaszczyk A. , Augustyn-PieniąŻek J.
Published: April 2015

The presented paper studies the effect of the casting technology on the corrosion resistance of Co-Cr-Mo alloy. The investigations were conducted on a commercial alloy with the brand name ARGELOY N.P SPECIAL (Co-Cr-Mo) produced by Argen as well as the same alloy melted and cast by the lost wax casting method performed by a dental technician. The corrosion behavior of the dental alloys in an artificial saliva was studied with the use of the following electrochemical techniques: open circuit potential and voltammetry. After the electrochemical tests, studies of the surface of the examined alloys were performed by means of a scanning electron microscope with an X-ray microanalyzer. The results of the electrochemical studies show that the dependence of the corrosion resistance on the microstructure associated with the recasting process is marginal. The results of the electrochemical studies of the considered alloy clearly point to their good corrosion resistance in the discussed environment.