bluuebunny/crossref_metadata_2025 huggingface dataset:
Uso da cetamina na analgesia preemptiva como forma de alívio da dor no pós-operatório imediato / Use of ketamine in preemptive analgesia as a form of pain relief in the immediate postoperative period
Authors: Sousa Ellen Karine Saraiva de , Melo Manuela Sobral Bentes de , Silva Ranyere Nobre da , Pinheiro Eyder Figueiredo , Lucena Douglas Alves , Bezerra Jéssica Fontenele , Leandro Jamille Ferreira , Landim Rafael Lucena , Ramos Antonio Augusto Jordão , Tavares Francisco Alexandre Braga , Batista Hermes Melo Teixeira
Published: May 2019

Os momento pós-operatório é tão relevante quanto o ato operatório em si, demandando manejo das dores advindas dessa atividade. Estudos têm demonstrado   que a analgesia no pós-operatório, em muitos casos, era realizada de forma inadequada. Este estudo objetiva analisar a o uso da cetamina na analgesia preemptiva como forma de alívio da dor no pós-operatório imediato, em estudos experimentais através de uma revisão na literatura. Os resultados dos estudos experimentais e clínicos aqui apresentados, apontaram que a S(+) cetamina é mais potente do que sua forma racêmica, indicando a superioridade daquela para fins de bloquear a sensibilização central, bem como que o uso da cetamina em pequenas doses na analgesia preemptiva, consiste no método mais eficaz no controle da dor do período pós-operatório. No entanto, ainda é muito restrito os artigos disponíveis sobre a temática, para fins de confirmar-se ou não, a efetividade dessa droga na analgesia preemptiva.
Estudo Sistematizado consoante a excelência na terapêutica com Toxina Botulínica do Tipo A em pacientes com Quadros de Hiperidrose / Systematized Study according to excellence in Botulinum Toxin Type A therapy in patients with Hyperhidrosis
Authors: Bernardes Nicole Blanco , Vasconcelos Esdras Haine Soares , Moraes Laisa Nazareth , Jesus Letícia Firmiano de , Silva Alessandra Bonacini Cheraim , Lélis Beatriz Dutra Brazão
Published: May 2019

A hiperidrose é uma doença benigna, relatada em menos de 1% da população e é uma alteração fisiológica que traz prejuízos imensos aos pacientes, evoluindo inclusive para fobias sociais. Alguns tratamentos convencionais não são eficazes ou arriscados em casos mais severos. A história clínica e o exame físico são ferramentas importantes na avaliação da gravidade e para indicação da terapia mais apropriada à cada caso. Para todos os graus de Hiperidrose, tem-se a terapêutica minimamente invasiva com Toxina Botulínica A que revela sua excelência, e o tratamento consiste basicamente em inibir os estímulos do sistema nervoso simpático. O objetivo desta pesquisa é correlacionar os tipos de hiperidroses e observar os efeitos da toxina botulínica do tipo A conceituando os aspectos relacionados ao diagnóstico, tratamento, qualidade de vida e a duração dos resultados obtidos. Trata-se de um estudo sistemático e explicativo fundamentado em artigos científicos que se encontram em consonância com os descritores controlados pela Biblioteca Virtual em Saúde (BVS), Banco de Dados SciELO e pelo Google Scholar. A partir dos dados sistematicamente coletados, conforme o método descrito acima pode-se verificar a qualidade do uso da Toxina Botulínica, em todos os diferentes tipos de Hiperidroses e, quando comparado a outras terapêuticas, clínicas ou cirúrgica, o custo de manutenção do tratamento com a Toxina demonstra ser mais o vantajoso. Apesar de ser um tratamento paliativo, é o que indigita o menor números negativos, tendo sua excelência na ausência de sudorese compensatória e, portanto, sugere-se a necessidade de o indicar como um primeiro tratamento.
Análise dos fatores que interferem na aprendizagem de alunos do 1º ao 3º do Ensino Fundamental no município de Ocara / Analysis of the factors that interfere in the learning of students from 1st to 3rd grade in the municipality of Ocara
Authors: Silva Verônica Holanda da , Hengemühle Adelar
Published: May 2019

Existem muitas discussões sobre as mudanças que o sistema educacional brasileiro tem sofrido nas últimas décadas, para atender às novas demandas provenientes do processo de universalização da educação. Porém, com base nessas mudanças é que se faz surgir o desafio de proporcionar educação de qualidade para todos. Desafios esses, que não são poucos nem tão pouco fáceis de enfrentar. No entanto, é preciso reconhecer que a educação já alcançou varias conquistas, pelo qual tem feito com que a esperança se renasça a cada novo dia. O presente trabalho parte do pressuposto que é preciso investigar, observar e analisar nossas escolas para conseguirmos obter resultados mais reais e significativos. Portanto, terá como objetivo analisar os aspectos que dificultam a aprendizagem de alunos do 1º ao 3º ano de uma escola pública de Ocara, tentando compreender até que ponto professores e escola podem contribuir para efetivar uma educação de qualidade. A população investigada foi de 40 sujeitos, entre professores, pais e alunos do 1º ao 3º ano, de escolas públicas de Ocara. Todos os sujeitos responderam a questionários que nos deram informações reais sobre o dia a dia de sala de aula e familiar, enfocando aos momentos de aprendizagem. Na verdade, teve um cunho investigativo como a finalidade de discutir, após os resultados na possível elaboração de estratégias que possa contribuir com a escola e secretaria de educação na efetivação de uma aprendizagem significativa.
Difa City Tour dan Pemenuhan Kebutuhan Wisata Difabel
Authors: Elfrida Tuti , Noviyanti Upik Dyah Eka
Published: May 2019

Various sectors seem to ignore the existence of persons with disabilities, including the tourism industry. The majority of tourist destinations have not provided accessible facilities for them. Transportation services also do not accommodate the mobility needs of persons with disabilities. This study focused on Ojek Difa in Yogyakarta. Through observation and interviews, qualitative data was obtained to see the recreational needs of persons with disabilities and how the roles of Ojek Difa. The study found that people with disabilities have different ways of defining tourism activities. Ojek Difa offers Difa City Tour to provide services for disabled people who want to take a tour in the city or visit other tourist destinations. The existence of Difa City Tour in the Ojek Difa organization shows the importance of involving service providers from groups of persons with disabilities in the tourism sector, especially in serving disabled tourists.[Berbagai sektor tampak mengabaikan keberadaan difabel, termasuk industri pariwisata. Mayoritas destinasi wisata belum menyediakan fasilitas yang aksesibel bagi difabel. Layanan transportasi juga kurang mengakomodasi kebutuhan mobilitas difabel. Penelitian ini terfokus pada Ojek Difa di Yogyakarta yang memberikan layanan mobilitas bagi para difabel. Melalui observasi dan wawancara, data kualitatif diperoleh untuk melihat kebutuhan wisata para difabel. Penelitian menemukan bahwa para difabel memiliki cara berbeda dalam mendefinisikan kegiatan wisata. Ojek Difa menawarkan Difa City Tour untuk menyediakan layanan bagi para difabel yang ingin melakukan tur dalam kota atau mengunjungi destinasi wisata lainnya. Eksistensi Difa City Tour dalam organisasi Ojek Difa menunjukkan pentingnya melibatkan pegawai atau penyedia layanan dari kelompok difabel di sektor pariwisata terutama dalam melayani para wisatawan difabel.]
Ekstraksi dan Uji Kestabilan Zat Warna Betasianin dari Kulit Buah Naga (Hylocereus polyrhizus) serta Aplikasinya sebagai Pewarna Alami Pangan
Authors: Agne Erza Bestari Pranutik , Hastuti Rum , Khabibi Khabibi
Published: May 2019

Kulit buah naga merupakan limbah hasil pertanian yang selama ini belum dimanfaatkan, padahal kulit buah naga mengandung zat warna alami betasianin cukup tinggi. Betasianin merupakan zat warna yang berperan memberikan warna merah dan merupakan golongan betalain yang berpotensi menjadi pewarna alami untuk pangan dan dapat dijadikan alternatif pengganti pewarna sintetik yang lebih aman bagi kesehatan. Penelitian bertujuan untuk mengekstrak zat warna betasianin dari kulit buah naga (Hylocereus polyrhizus) dan diaplikasikan sebagai pewarna alami pangan. Ekstraksi betasianin dilakukan dengan metode maserasi menggunakan pelarut etanol 80%. Parameter yang diterapkan pada penentuan kestabilan ekstrak yang diperoleh adalah pemanasan pada temperatur 25°C-100°C, variasi pH 2,5- 9,5, dan pembandingan dengan perlakuan pemanasan dan paparan cahaya matahari. Serbuk betasianin diperoleh dengan pengeringan ekstrak betasianin menggunakan metode freeze drying. Serbuk betasianin yang diperoleh diaplikasikan sebagai pewarna alami pangan, seperti yoghurt, es krim, dan adonan kue bolu. Pada uji kestabilan betasianin terhadap perubahan temperatur dan perubahan pH diperoleh warna betasianin paling stabil pada pH 4,5 dan pada temperatur di bawah 40°C. Ekstrak yang ditambahkan asam, stabil terhadap pemanasan dan paparan cahaya matahari. Serbuk betasianin dapat diaplikasikan sebagai pewarna alami pangan untuk makanan yang penyimpanannya dalam suhu rendah seperti es krim dan yoghurt.
Pembuatan Elektrolit Padat KMn2-xMgxO4 dengan Variasi Konsentrasi Larutan Kalium Asetat
Authors: Harjono Cipto , Suyati Linda , Nuryanto Rahmad
Published: May 2019

Proses pembuatan elektolit padat KMn2-xMgxO4 dengan variasi konsentrasi larutan kalium asetat telah dilakukan. Kalium sebagai ion logam dalam elektrolit padat berfungsi sebagai penghasil energi dengan proses elektrolisis sehingga perlu ditinjau pengaruh perubahan konsentrasi terhadap struktur dan daya hantar (konduktivitas). Penelitian ini menggunakan pemanasan secara bertahap dan metode sol-gel yaitu dengan mencampurkan larutan CH3COOK 0,1-0,5M, Mg(CH3COO)2 0,3M, Mn(CH3COO)2 dan C6H8O7 0,3M dengan pengadukan disertai pemanasan suhu 80°C, pengeringan pada 175°C, dan kalsinasi 650°C. Peningkatan konsentrasi mengakibatkan penurunan konduktivitas yaitu pada konsentrasi 0,1 M sebesar 36,90 S/m menjadi 13,75 S/m pada konsentrasi 0,5 M. Hasil FTIR menunjukkan adanya puncak 3332,99 cm-1dan 3170,97 cm-1 (K-O-Mn bending), 594,08 dan 478,35 cm-1 (Mg-O stretching), 1450,47 dan 1404,18 cm-1 (K-O stretching). Hasil XRD menunjukkan bahwa semua produk dalam bentuk kristalin dan struktur yang terbentuk adalah KMn1,7Mg0,3O4
Innovation of Carbon from Pectin Templated in Fabrication of Interlayer-free Silica-Pectin Membrane
Authors: Pratiwi Amalia Enggar , Elma Muthia , Putra Meilana Dharma , Mirwan Agus , Rahma Aulia , Rampun Erdina Lulu Atika
Published: May 2019

Water scarcity is the main issues in Indonesia especially for coastal areas. As a consequence, the water has high salinity of >50.000 ppm salt concentration where an appropriate treatment is necessary before consumed. In this case, desalination process could be carried out using inorganic silica membranes. However, during the process the pore of silica membranes were collapsed due to the directly contact of pores to water molecules for a long term performance. Thereby, in this work the innovation of membrane fabrication using carbon templated in silica matrices has been successfully fabricated. Literally, the carbon templates could be improving the membrane hydro-stability. The interlayer-free silica-pectin membrane was fabricated using TEOS as silica precursor and carbon templated from pectin apple. All membranes waere calcined in variance temperature of 300 and 400°C via Rapid Thermal Processing (RTP). The FTIR results show some functionalization of siloxane, silanol and a new bond of silica-carbon. Whereas, the SEM images show the membrane morphology that the membrane not dense and crack-free with thin film's thickness of ~ 1 μm. An excellent condition of interlayer-free silica-pectin membrane was obtained at pectin concentration of 2.5 %wt. (300°C) and 0.5 %wt. (400°C) with highest functionalization of siloxane and silica-carbon bonds. The existence of silica-carbon bonds were capable to enhancing the membrane hydro-stability. In addition, the carbon chains were contributed to form a smaller pores but also robust pore structures. Those fabricated membranes were shown a good promising due to fast and low cost fabrication with high quality to applicate in seawater desalination.
Zamiast wstępu
Authors: Sommerfeld Beate , Walkiewicz Barbara
Published: May 2019

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Geolektalne pułapki języka hiszpańskiego w praktyce przekładu pisemnego i ustnego
Authors: Kwiatkowska Faryś Edyta , Wolarska-Sobocińska Agata
Published: May 2019

In the translatological perspective, the pluricentricity and big number of standard varietes of the Spanish language is a challenge, especially at the semantic and lexical level, as well as the phonetics and pragmatics are concerned. This study is an attempt to present the complexity and multidimensionality of the problem. On the basis of selected specific examples, the paper shows how the ability to recognize and distinguish specific geolects equips a translator/interpreter of Spanish with the tools of effective communication and a culture oriented interpretation.
Dylematy nauczyciela akademickiego kierującego seminarium magisterskim w ramach studiów tłumaczeniowych
Authors: Tomaszkiewicz Teresa
Published: May 2019

The following paper discusses the role of an MA seminar and an MA thesis in the process of education of professional translators who are more oriented toward gaining knowledge and skills instead of research activities. The Author, basing upon own experiences, aims to present dilemmas which academic teachers face while conducting such seminars as well as to explain how they can target students’ actions, so they can combine research activities with professional practice as part of a given educational path.
Identyfikacja gatunku mowy pochwały w oparciu o strategię reaktywnego gatunku mowy (SRGM)
Authors: Wartecka Anna
Published: May 2019

The main purpose of this article is to explain the procedure of identifying the utterances of praise using the Reactive Speech Genre Strategy (RSGS). The RSGS is one of the steps of a wider strategy dedicated to identification of “Praise” speech genre. In the article are described 5 stages of RSGS, which include considerations over: the initiative nature of “Praise” speech genre; the role of the reactive nature of “Gratitude” speech genre in identifying the “Praise” speech genre; the analysis of selected speech genres associated with “Praise” and “Gratitude”. The linguistic corpus consists of selected utterances of positive assessment taken from the Polish version of a television talent show “Mam talent!”.
Outplacement jako narzędzie polityki społecznej odpowiedzialności przedsiębiorstw w Unii Europejskiej
Authors: Greficz Magdalena
Published: May 2019

Procesy restrukturyzacji zatrudnienia stanowią jeden z najbardziej dotkliwych społecznie efektów zmian zachodzących współcześnie w państwach Unii Europejskiej, wynikających z trwającego od 2008 r. kryzysu gospodarczego. Wydawałoby się, że wobec trudności gospodarczych przedsiębiorstwa będą skupiały się na poprawie wyników finansowych, rezygnując ze stosowania polityki społecznej odpowiedzialności (Corporate Social Responsibility - CSR). Jednym z przykładów działań odpowiedzialnie społecznych, stosowanych przez przedsiębiorstwa podczas kryzysujest outplacement. Celem artykułujest przybliżenie istoty outplacementu poprzez analizę literatury przedmiotu z zakresu restrukturyzacji zatrudnienia oraz społecznej odpowiedzialności biznesu, w tym zwłaszcza kwestii narzędzi stosowanych przez przedsiębiorstwa w celu łagodzenia negatywnych skutków zwalniania pracowników. Charakterystyka outplacementu została przedstawiona w kontekście uregulowań prawnych i inicjatyw Unii Europejskiej oraz Polski, a także praktycznych rozwiązań z zakresu CSR, stosowanych przez przedsiębiorstwa w ramach programów outplacementu.
Uwarunkowania polityki integracyjnej wobec muzułmanów w Szwecji
Authors: Gołębiowska Klaudia
Published: May 2019

Po drugiej wojnie światowej, państwa europejskie zaczęły być atrakcyjnymi celami migracji, otwierając swoje granice aby odbudować zniszczone gospodarki. Imigranci często nie byli w stanie zabrać ze sobą swojego dobytku materialnego. Zawsze jednak zabierały swój „dobytek kulturowy’’, na który składały się nie tylko wyuczone sposoby zachowania się i porozumiewania z innymi, ale także tradycje, przekonania i wierzenia religijne. Ich przybycie do Europy Zachodniej sprawiło, że zamieszkujące je społeczeństwa stały się nie tylko bardziej wielokulturowe, ale również bardziej wieloreligijne. Celem artykułu jest zbadanie polityki integracyjnej wobec mniejszości muzułmańskiej w Szwecji oraz jej uwarunkowań, aby określić wskazówki dla kreatorów analizowanej polityki w innych państwach (także i w Polsce) oraz określić płaszczyzny, na których dochodzi do antagonizmów w społeczeństwie. Polityka integracyjna jest istotnym i nieodłącznym elementem składowym polityki migracyjnej i stanowi aktualne wyzwanie dla wielu państw.
Rozdźwięk pomiędzy liberalną retoryką a społeczno-polityczną rzeczywistością współczesnych stosunków międzynarodowych - przykład Europy Środkowo-Wschodniej
Authors: Więcławski Jacek
Published: May 2019

Niniejszy artykuł dotyczy rozdźwięku pomiędzy liberalną retoryką a społeczno- polityczną rzeczywistością współczesnych stosunków międzynarodowych. Autor twierdzi, że jakkolwiek liberalizm nadal zapewnia wiodącą perspektywę eksplanacyjną współczesne stosunki międzynarodowe są zbyt dynamiczne i skomplikowane aby można było zanalizować je wyłącznie w ramach liberalizmu, który zresztą popada w dogmatyzm. Z tego powodu, adekwatna analiza współczesnej demokracji oraz politycznych i gospodarczych aspektów współczesnych stosunków międzynarodowych jest niepełna, jeśli nie uwzględnia pewnych wniosków ze sfery realizmu, konstruktywizmu, a nawet postmodernizmu. Przykład transformacji demokratycznej w Europie Środkowo-Wschodniej doskonale obrazuje tę tezę. Liberalne reformy w regionie wciąż zderzają się z rygorystycznymi poglądami wywodzącymi się z socjalistycznej przeszłości. Liberalne wartości sąpoza tym zniekształcane i błędnie pojmowane. Wyjaśnianie tych procesów wykracza daleko poza liberalizm i analiza nawet samego wschodniego poszerzenia Unii Europejskiej byłaby bardziej wyczerpująca gdyby uwzględniła pewne odniesienia do realizmu, krytyki teoretycznej czy postmodernizmu.
Returning to the Heavens: Plato’s Socrates on Anaxagoras and Natural Philosophy
Authors: Flores Samuel Ortencio
Published: May 2019

Readers of Plato since antiquity have generally taken Socrates’ intellectual autobiography in the Phaedo as a signal of his turn away from the study of natural philosophy. They have turned instead to characters such as Timaeus for evidence of Plato’s pursuit of physics. This article argues that Plato’s Socrates himself developed a philosophy of nature in his criticism of Anaxagoras and his subsequent philosophic pursuits. Socrates’ autobiography places the study of nature in a foundational position within the development of his philosophic method. In the Apology, Socrates further elaborated his investigation into nature through his understanding of theology. Finally, in the Phaedrus, Socrates connects the study of nature with the study of rhetoric as tools for virtue. Therefore, Plato’s Socrates does not reject or abandon physics, as has often been suggested, but rather, he incorporates it into his own philosophic project and challenges its practitioners to connect their own inquiries with human affairs.
Rheological and Structural Changes During the Mixing of Suspensions and Emulsions
Authors: Hugelshofer D. , Windhab E. J. , Wang J.
Published: May 2019

The rheological effects occuring when an emulsion is mixed with a suspension can be detected using a helical ribbon stirrer. The stirrer rotates in a rheometer cup and is connected to the torque sensor of the rheometer. During mixing, microstructural changes which are related to the interactions between the continuous fluid phase and the disperse droplets (or disperse solid particles) as well as between droplets and particles will have a strong impact on the measured apparent viscosity. Phase interactions and surfactant influences can thereby be described in terms of their effect on the viscosity of the mixture. The viscosity trend during the mixing time is strongly dependent from the disperse phase concentration of the suspension, the polarity of the suspension particles and from the nature of the emulsifiers used. When a structural equilibrium is reached, the apparent viscosity as measured with the stirrer can be recalculated using the Rieger-Novak and the Metzner-Otto approach. This allows for a comparison of the apparent viscosities as determined by means of the stirrer and viscosities as determined in uniaxial shear in the concentric cylinder geometry. As microscopic observations demonstrate, the final state of the mixture of emulsion and suspension is the state with the energy minimum of the interfacial system, i.e. the total interfacial area is minimised by forming water containing agglomerates in a continuous oil phase.
Thermomechanical Properties of Several Polymer Modified Asphalts
Authors: Zanzotto Ludo , Stastna Jiri , Vacin Otakar
Published: May 2019

Costly deterioration of many roads and highways paved with asphalt generates a growing interest in polymer modified asphalts (PMA). Although asphalt represents only a fraction of asphalt paving mix, it is believed that it has a significant effect on the thermomechanical properties of asphalt pavements. Currently there is no consensus on the type of tests and specifications for polymer modified asphalts; however, it is clear that such specifications should be based on rheological testing of these systems. As a viscoelastic material asphalt is usually characterized by its dynamic material functions. An advantage of the use of modified loss tangent function in PMA systems is discussed in this contribution. Three polymer modifiers (SBS, EVA and EGA) commonly used in the asphalt paving industry were blended with base asphalt and various relaxations in the base, and its blends are studied here.
Transient Measurements in Rate Controlled Rheometers: A New Method of Standardization
Authors: Talbi-Boucenna Imane , Quemada Daniel
Published: May 2019

Rheological measurements in response to transient shear rate exhibit coupling effects between mechanical characteristics of rheometer and unsteady (thixotropic and viscoelastic) properties of fluid. This coupling is observed if the characteristic times of the latter lie in the range of those associated to mechanical properties of the apparatus. Damped oscillations observed in the stress relaxation curves obtained with some standard oils submitted to stress steps are an example of this type of anomalous responses. This work introduces a new method of standardization for a low shear rate rheometer (Contraves LS40) under unsteady flow conditions. This “standardization under transient conditions” is developed in order to obtain a correct interpretation of unsteady measurements performed on elastic and thixotropic fluids, hence to permit modelling of the latter. A second order differential operator is supposed capable to describe the fluid-rheometer coupling. A series of measurements on standard silicone oils, which include electromechanical characteristics of the instrument, allow us to determine the parameters involved in this operator. Then, a preliminary test of this method is performed on a typical system (Red Blood Cell suspension with Dextran) which presents viscoelastic and thixotropic behavior.
Material’s Volumetric-Flow Rate (MVR) as a Unification Parameter in Asphalt Rheology and Quality Control / Quality Assurance Tool for High Temperature Performance Grading
Authors: Shenoy Aroon
Published: May 2019

Rheological data of unmodified and polymer-modified asphalts are conventionally obtained from dynamic mechanical characterization and expressed in terms of sets of curves showing the variation of viscoelastic properties with frequency. Using the conventional melt flow indexer, the material’s volumetric-flow rate MVR (in cm3 / 10 minutes) through a predefined die under conditions of constant temperature and stress when obtained for the same asphalts, shows a direct relationship with the dynamic data. The MVR value helps in unifying the sets of dynamic data curves of |G*|, G” and |G* |/sin δ versus frequency in the case of unmodified asphalts, polymer-modified asphalts and asphalt mastics. The unification technique has a sound theoretical basis and the unified curves have far-reaching implications. Since MVR is so simple to determine quite accurately on a relatively inexpensive, easy-to-use flow measurement device (FMD), this parameter can be generated on paving sites or at refineries, if needed, rather than in research laboratories as is the case with the fundamental rheological parameters. The MVR can then be used as an excellent indicator of the fundamental rheological parameters through the use of the unified curves. The MVR can be utilized to accurately determine the currently used high temperature performance grade specification of paving asphalt. On account of the simplicity in obtaining this specification value from the MVR, it may be routinely used for quality control / quality assurance purposes. It can also be used as a rapid product development / formulation tool.
Melt Rheology of Tin Phosphate Glasses
Authors: Adalja Sunil B. , Otaigbe Joshua U.
Published: May 2019

The melt rheology of a low T

g
tin phosphate glass [Pglass] has been studied with oscillatory shear flow experiments to accelerate efforts to melt process the glass with different organic polymers. The w dependence of the complex viscosity η* of the Pglass is easily predicted by a modified Rouse model with two relaxation times. The complex viscosity of the glass at different temperatures and frequencies can be superposed and described by the Arrhenius equation. At higher temperatures, the melt viscosity of the Pglass increased monotonically with time. This viscosity rise is thought to be due to sample crystallization. The Pglass was melt-mixed with two different thermoplastic polymers (low-density polyethylene and polystyrene) to produce unique hybrid materials with interesting microstructures.
Milk Fat Composition Affects Mechanical and Rheological Properties of Processed Cheese
Authors: Jaros D. , Petrag J. , Rohm H. , Ulberth F.
Published: May 2019

Laboratory-scale experiments were carried out to explore the influence of the composition of the fat phase on mechanical and rheological properties of processed model cheeses. Cheeses made from caseinates, emulsifying salts and a milk fat fraction liquid at 24°C, which was achieved by thermal separation, showed much lower moduli than processed model cheeses manufactured with a fat fraction solid at 30°C. Processed model cheeses made from caseinates, emulsifying salts and a hard butter with a low amount of unsaturated fatty acids were significantly higher in firmness than cheeses made with soft butter with a higher amount of unsaturated fatty acids. In experiments using mature Gruyère and emulsifying salts, processed cheeses made from summer Gruyère were less firm than processed winter Gruyère. The results indicate that fat composition strongly affects mechanical properties of processed cheese, and a model is provided to explain structural changes during deformation.
Vane Sensor System in Small Strain Oscillatroy Testing
Authors: Junus Silvara , Briggs Jenni L.
Published: May 2019

To overcome difficulties (slip, sample disturbance) associated with traditional sensors, a semi-empirical method was developed to allow the use of a 4-bladed vane sensor in small strain oscillatory testing. It was assumed that the vane sensor acted as a bob with an acting radius, RV, different from the actual radius of the vane (0.02005 m). To solve for RV, the complex modulus obtained using a concentric cylinder sensor from reference viscoelastic fluid, was set equal to the complex modulus equation for vane sensor. RV values were grouped into three phase shift ranges from 5° to less than 16°, from 16° to less than 60°, and from 60° to 90° and they were 0.01883, 0.01869, and 0.01850 m, respectively. These values were used in the calculation of viscoelastic properties of eight commercial food products, which resulted in complex modulus values within 15% of those obtained using a concentric cylinder sensor. Results showed that this particular vane and cup system can be used to directly measure the storage and loss moduli of viscoelastic material and phase shift within the upper frequency value of 6.28 rad/s. Above 6.28 rad/s, there is an inconsistency in phase shift angles measured using vane method. This method is ideal for testing thixotropic food systems because disturbance is minimal during sample loading, giving more accurate viscoelastic measurements.
On-Line Rheometry for Twin-Screw Extrusion (Along the Extruder) and its Applications
Authors: Maia J. M. , Carneiro O. S. , Machado A. V. , Covas J. A.
Published: May 2019

Due to a number of practical difficulties, both in- and on-line measurements of the rheological properties of complex systems during extrusion are usually performed at the end of the extruder, under very specific experimental conditions. This makes this type of instruments more useful for quality control than for process optimisation, since information about the influence of the geometry and/or processing conditions on the evolution of the material characteristics inside the extruder is not easily gathered. Recently, however, the authors have developed an on-line capillary rheometry system that overcomes most of the existing problems and allows small amounts of sample to be tested in very near real time, along the extruder. The present work aims at illustrating the usefulness of this concept for the study of physical compounding processes and some reactive systems. Two very different systems will be used for that purpose: a reactive extrusion process (the peroxide-induced thermal degradation of polypropylene) and the dispersive mixing involved in the preparation of thermoplastic/carbon fibre composites.
Magneto Sweep – A New Method for Characterizing the Viscoelastic Properties of Magneto-Rheological Fluids
Authors: Wollny Klaus , Läuger Jörg , Huck Siegfried
Published: May 2019

The viscoelastic properties of a magneto-rheological fluid can be variably controlled using a magnetic field. A new measuring method is introduced which is based on oscillatory tests. In contrast to flow curves from experiments at steady shear rate, the new method allows an exact determination of a magneto-rheological fluid’s viscoelastic properties as a function of the preset magnetic field strength. The “Magneto Sweep” is an oscillatory test method, each with constant amplitude and constant frequency while logarithmically increasing the magnetic field strength (Magneto Sweep). For typical magneto-rheological fluids (MRF) three characteristic regions and two significant transition points can be determined. These transitions mark the corresponding change in material behavior resulting from an increasing magnetic field strength.
On numerical Simulations of Polymer Extrusion Instabilities
Authors: Achilleos Evdokia , Georgiou Georgios C. , Hatzikiriakos Savvas G.
Published: May 2019

The objective of this study is mainly to review recent work concerning the numerical modeling of the stick-slip and gross melt fracture polymer extrusion instabilities. Three different mechanisms of instability are discussed: (a) combination of nonlinear slip with compressibility; (b) combination of nonlinear slip with elasticity; and (c) constitutive instabilities. Furthermore, preliminary numerical simulations of the time-dependent, compressible extrudate-swell flow of a Carreau fluid with slip at the wall, using a realistic macroscopic slip equation that is based on experimental data for a high-density polyethylene, are presented.
Evaluation of a helical ribbon impeller as a viscosity measuring device for fluid foods with particles
Authors: Eriksson I. , Bolmstedt U. , Axelsson A.
Published: May 2019

The traditional methods of measuring viscosity with rotational viscometers, i.e. cone-plate and concentric cylinder systems, are often not suitable for suspensions. To be able to measure viscosity on suspensions mixer viscometers have been developed. In this study a new design of a helical ribbon impeller has been evaluated and the Metzner-Otto approach has been used to calibrate the impeller. Different kinds of food products were studied. The Metzner-Otto parameter obtained from tomato products was lower than those obtained from starch products. The study showed that the Metzner-Otto parameter varied but seemed rather to be dependent on the composition of the food material than on the flow behaviour index. The impeller could handle high concentration of quite large particles. This type of helical ribbon impeller viscometer is thus recommended for rheological studies of suspensions with high concentration of particles.
Flow Patterns of Polymer Solutions Injected into Dispersions of Bentonite
Authors: Beckmann Sabine , Niemeyer Jürgen
Published: May 2019

The flow behaviour of colloidal dispersions is largely influenced by the interactions between the dispersed particles. We studied the influence of either natural or synthetic polyelectrolytes solutions on flow patterns within colloidal clay dispersion. For this purpose, highly diluted aqueous polymer solutions were intruded into a radial Hele-Shaw cell filled with montmorillonite dispersions. The developing flow patterns were recorded with a high resolution digital camera. The morphological parameters: fractal dimension, total number of branching, branching density of the patterns, compactness and form were obtained by digital image analysis. The results show that the patterns are largely affected by the different polymers.
Numerical Simulation of Sharkskin Phenomena in Polymer Melts
Authors: Nithi-Uthai Nattapong , Manas-Zloczower Ica
Published: May 2019

A fluid dynamic analysis package, PolyFlow, based on the finite element method is used to study the sharkskin phenomenon. A stick-slip mechanism is used as the basis for the simulations. This study is aimed at illustrating how fluctuations in the stress at the exit from the die cause similar fluctuations in the extrudate swell ratio, resembling the sharkskin phenomenon. Such fluctuations in the stress at the exit from the die are produced by implementing a stick-slip boundary condition at the die wall, mimicking a mechanism of molecular entanglement/disentanglement at the wall. We use a superposition of stress relaxation/stress growth and a periodic change in extrudate swell governed by the die exit stress level to depict sharkskin. Three relatively monodisperse polybutadienes were used in this study. The simulated sharkskin time period was found to be in good agreement with experimental findings. We found that the simulated pictures of sharkskin are similar for all three molecular weight samples. A comparison between the simulated sharkskin and experimental results show qualitative resemblance. The main problems preventing us from generating more quantitative sharkskin results mainly reside in the model limitations in depicting stress singularity, limitations in mesh design refinement and the constitutive model employed. In spite of these limitations, the qualitative agreement between simulation results and experimental data is good.
The Influence of Thickener Addition on Filter Cake Formation During Dewatering of Mineral Suspensions
Authors: Jäder Jerker , Järnström Lars
Published: May 2019

A novel method to continuously measure the rate of build-up of an immobilised layer (apparent filter cake) was demonstrated for three mineral suspensions containing carboxymethyl cellulose and polymer latex. These suspensions were designed to be similar to those normally used as coating colours within the paper industry. The instrumentation was based on a rheometer equipped with units for controlling (and measuring) the normal forces acting on the rotating upper plate and precise measurements of the gap height in parallel–plate geometry. The bottom plate in the measurement cell was perforated and connected to vacuum, giving the driving pressure for flow through the filter. The technique should so far be taken as a qualitative, but is an attractive method for measuring filtration in thin films under controlled shear rate. The technique enables the apparent filter cake height to be calculated at any time during dewatering of the coating colours.
Plastic Fluid Flow Parameters Identification Using a Simple Squeezing Test
Authors: Roussel Nicolas , Lanos Christophe
Published: May 2019

In this paper after a presentation of the compression test and its classical references in the rheological literature a behaviour parameter identification method is introduced using simple compression tests on concentrated geo-suspensions with a plastic fluid behaviour. The obtained theoretical test response is validated for several materials (natural soils, Kaolin clay …). It is also compared with previous solutions obtained by other authors to show that most existing solutions miss one or more terms. Elements are also given on two types of test response perturbations: the induced heterogeneity in the case of slow tests (consolidation phenomena) and the fragmentation of the outer part of sample (granular paste breakings). Finally, compression test results for a nano silica paste are presented as a example and treated as an application of the test exploitation method.
Viscoelastic Characterization of Polymer-Modified Asphalt Binders of Pavement Applications
Authors: Uddin Waheed
Published: May 2019

Rutting is a primary reason of premature deterioration of asphalt highway pavements. Pavements constructed with polymer and other modifiers are showing improved performance. The virgin asphalt and modified asphalt binders and mixes used on several test sections of the I-55 highway rehabilitation project in northern Mississippi are compared. The laboratory creep compliance data for these binders were measured at low temperatures using a modified test procedure adapted for the Bending Beam Rheometer device. Dynamic Shear Rheometer was used at high service temperatures. The creep compliance data of the binder was used as an input to simulate creep compliance behavior of the mix using a micromechanical model. The field evaluation confirms the relatively poor performance of the virgin asphalt section with respect to rutting, compared to modified binder sections.
Talc Filled Thermoplastic Composites: Melt Rheological Properties
Authors: Mederic P. , Moan M. , Klopffer M.-H. , Saint-Gerard Y.
Published: May 2019

The effects of composition and resulting morphology on the rheology of thermoplastics filled with different talc platelets were studied in the 0-22% range of volume fraction, Φ. The sufficiently filled polymer composites exhibit a rheological behavior which significantly differs from the pure polymers used in this work, a linear low density polyethylene, a low density polyethylene and a polyamide 12. The changes in the rheological behavior are influenced by the size, the concentration and the surface treatment of plate-like talc particles. They also depend on the chemical nature and viscous and elastic characteristics of the polymer matrix. In particular, the effect of platelet orientation on the viscoelastic properties of reinforced composites was pointed out. For sufficiently filled systems, a low frequency response indicative of a pseudo solid-like behavior is obtained only during the first frequency sweep. In fact, the low frequency storage modulus, G’, is constant. With repeated frequency sweeps, more platelets were aligned in the flow direction, thus the low frequency storage modulus gradually decreases and becomes dependent on frequency, ω. The low frequency complex viscosity η* also progressively decreases with repeated frequency sweeps. In addition, for these systems, the low shear viscosity η build up in an unbounded manner because of the existence of particle-particle interactions. There are stresses below which there is no flow indicating the existence of yield values. Steady shear elastic properties are also studied, especially in the case of systems showing an apparent yield stress.
Is the Choice of Flow Curve Fitting Equation Crucial for the Estimation of Pumping Characteristics?
Authors: Malkin A.Ya. , Masalova I. , Pavlovski D. , Slatter P.
Published: May 2019

The answer to this provocative question is “no”! This is demonstrated by experiment and analysis for two very different materials – a highly concentrated emulsion and an 8%v/v Kaolin clay suspension. The flow curves of both materials clearly showed a low shear Newtonian asymptote and a pseudoplastic domain. The difference in the accuracy of the fitting equations relates mainly to the low shear rate domain. While the Cross equation is adequate over the full flow curve, the power law and the Herschel-Bulkley equations are clearly inadequate for the low shear rate range. These equations as well as the direct numerical method (using the Rabinowitsch-Weissenberg integral) were used for the calculation of the laminar pipe flow transport characteristics and the results were compared with experimental pipe flow data. It was shown that in all cases the maximum error did not exceed 5%, which is quite acceptable for engineering design, indicating that the choice of the flow curve fitting equation was unimportant.
Evaluating Viscosity of Surimi Paste at Different Moisture Contents
Authors: Yoon Won B. , Gunasekaran Sundaram , Park Jae W.
Published: May 2019

The steady and dynamic shear viscosity of fish muscle protein paste obtained from Alaska pollock surimi at 95%, 90%, 85%, 80%, and 75% of moisture contents were measured in the temperature range of 5°C to 20°C. To estimate the steady shear viscosity at high shear rate from dynamic shear viscosity, the modified Cox-Merz rule was applied by introducing a frequency shift factor. The concentration dependence of zero-shear viscosity showed power-law dependence with an exponent of 3.5, and the universal behavior of viscosity at different protein concentrations was observed by a introducing reduced variables. The Carreau model was applied to describe the shear- thinning behavior of the surimi paste, and the model parameters estimated empirically showed moisture content dependence. The viscous flow behavior was independent of temperature (5°C to 20°C), and addition of starch decreased the flow index and viscosity of the paste, compared to the pure surimi paste.
Viscosity Function for Yield-Stress Liquids
Authors: Souza Mendes Paulo R. , Dutra Eduardo S. S.
Published: May 2019

A viscosity function for highly-shear-thinning or yield-stress liquids such as pastes and slurries is proposed. This function is continuous and presents a low shear-rate viscosity plateau, followed by a sharp viscosity drop at a threshold shear stress value (yield stress), and a subsequent power-law region. The equation was fitted to data for Carbopol aqueous solutions at two different concentrations, a drilling fluid, an water/oil emulsion, a commercial mayonnaise, and a paper coating formulation. The quality of the fittings was generally good.
A Comprehensive Treatise of the High Temperature Specification Parameter |G*|/(1-(1/tanδsinδ)) for Performance Grading of Asphalts
Authors: Shenoy Aroon
Published: May 2019

The term |G*|/(1-(1/tanδ sinδ)) has been suggested as one of the best candidates for the replacement of the Super-pave specification parameter |G*|/sinδ, which has been found to be inadequate in rating polymer-modified binders for high temperature performance grading. This refinement of the Superpave specification parameter evolved through a theoretical derivation based on fundamental concepts. It was shown to be more sensitive to the variations in the phase angle δ than the original Superpave specification parameter. It thus described the unrecovered strain in the asphalt binders more accurately, and hence related to actual field performance data. This article provides a comprehensive treatise of the parameter |G*|/(1-(1/tanδ sinδ)) giving details of its derivation, salient features that are attributed to its success, comparison with actual field performance data for validation and a one-on-one comparison with the existing parameter |G*|/sinδ. It is shown that for all available field data, the parameter |G*|/(1-(1/tanδ sinδ)) does a better job in correlating with the rutting behavior than the parameter |G*|/sinδ for unmodified as well as modified asphalts. Since it is obtained in the same manner as the parameter |G*|/sinδ through the determination of |G*| and δ from a stress-controlled or strain-controlled dynamic shear rheometer, it means that no retraining of technicians and staff is required and implementation for the use of this parameter is immediate, thereby saving enormous amount of time and money. This parameter has the further advantage of being in a form easily adaptable to modeling, and thereby directly applicable for pavement design purposes.
Characteristic Times of Microsturcture Formation in Electrorheological Fluids, Determined by Viscosity and Speckle Activity Measurements
Authors: Alanis Elvio , Romero Graciela , Martinez Carlos , Alvarez Liliana , Mechetti Magdalena
Published: May 2019

Viscosity measurements of a suspension of cornstarch in silicone oil, at several concentrations and subject to different electrical field strengths, were conducted. An increase in the apparent viscosity, in correlation with the field strength, which is characteristic of the so-called electrorheological fluids (ERF), was observed. For a given field intensity, the value of the viscosity increases rapidly in the first seconds after the application of the electric field, and then it increases slowly until it finally approaches a saturation value. This behaviour of the apparent viscosity has been related to the microstructure formation due to interactions between dipoles induced by the electric field. Characteristic times, related to structure formation after application of an electric field, are investigated by means of diffuse light transmission and speckle-pattern activity measurements. Two characteristic times were found that should be related to the state of aggregation of the suspended particles: orientation of the non-isotropic particles and later chain formation. These results agree reasonably with that obtained from electrorheological measurements. Microscopic observations of structure formation are also reported.
A Mean Flow Model for Polymer and Fiber Turbulent Drag Reduction
Authors: Roy Anshuman , Larson Ronald G.
Published: May 2019

We present a one-parameter model that fits quantitatively the mean velocity profiles from experiments and numerical simulations of drag-reduced wall-bounded flows of dilute solutions of polymers and non-Brownian fibers in the low and modest drag reduction regime. The model is based on a viscous mechanism of drag reduction, in which either extended polymers or non-Brownian fibers increase the extensional viscosity of the fluid and thereby suppress both small and large turbulent eddies and reduce momentum transfer to the wall, resulting in drag reduction. Our model provides a rheological interpretation of the upward parallel shift S+ in the mean velocity profile upon addition of polymer, observed by Virk. We show that Virk’s correlations for the dependence on polymer molecular weight and concentration of the onset wall shear stress and slope increment on the Prandtl-Karman plot can be translated to two dimensionless numbers, namely an onset Weissenberg number and an asymptotic Trouton ratio of maximum extensional viscosity to zero-shear viscosity. We believe that our model, while simple, captures the essential features of drag reduction that are universal to flexible polymers and fibers, and, unlike the Virk phenomenology, can easily be extended to flows with inhomogeneous polymer or fiber concentration fields.