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Flexural behavior of Sisal/Castor oil-Based Polyurethane and Sisal/Phenolic Composites
Milanese, Andressa Cecília;Cioffi, Maria Odila Hilário;Voorwald, Herman Jacobus Cornelis;
Materials Research , 2012, DOI: 10.1590/S1516-14392012005000019
Abstract: natural fibers used as reinforcement of polymeric composites are interesting research subjects in polymer technology. nowadays, these materials are being considered as a way to reinforce timber structures improvement. fibers with larger structural applications are glass and carbon fibers, however, the use of natural fibers is an economic alternative and present many advantages such as biodegradability and having its origin from a renewable source. castor oil, a triglyceride vegetable with hydroxyl groups, was reacted with 4,4' methylene diphenyl diisocyanate (mdi) to produce the polyurethane matrix. the composites were prepared by compress molding at room temperature using woven sisal fiber as a reinforcement, with and without thermal treatment (at 60 oc for 72 hours) to the fabrics before the composites molding process. the present paper presents the preparation and a flexural caracterization of sisal/polyurethane and sisal/phenolic composites by using the three-point bending. the sisal fibers moisture content influence on the flexural behaviour was also analyzed. experimental results showed a higher stiffness for the sisal/phenolic composite (11.2 mpa) followed by the sisal/polyurethane (3.7 mpa), respectively.
Effect of a Shot Peening Pre Treatment on the Fatigue Behaviour of Hard Chromium on Electroless Nickel Interlayer Coated AISI 4340 Aeronautical Steel
Nascimento, Marcelino P.;Torres, Marcelo A.S.;Souza, Renato C.;Voorwald, Herman J.C.;
Materials Research , 2002, DOI: 10.1590/S1516-14392002000200002
Abstract: multiple layer systems of coatings are considered to have larger resistance to crack propagation in comparison to coatings with simple layer. with regard to fatigue, it is possible to improve the resistance of a component with the application of shot peening treatment, whose compressive residual stresses delay or eliminate the initiation and propagation of fatigue cracks. the aim of this study is to analyse the effects on rotating bending fatigue behaviour of hard chromium ？ electroless nickel multilayer system coated aisi 4340 high strength steel submitted to shot peening pre treatment. results indicated that the interaction between the shot peening process with the multilayer system was not satisfactory, resulting in intense delamination. fracture surface analysis by sem was performed toward to identify the fatigue crack origin, as well as the coating-substrate delamination process.
Mummified papyraceous fetuses in the abdominal cavity of an elderly female dog with pyometra
Voorwald, F.A.;Tiosso, C.F.;Cardilli, D.J.;Toniollo, G.H.;
Arquivo Brasileiro de Medicina Veterinária e Zootecnia , 2012, DOI: 10.1590/S0102-09352012000200009
Abstract: this paper reports on a rare case of fetal papyraceous mummification after asymptomatic uterine rupture in an elderly female dog with pyometra. the patient had a history of mating six months before the examination but no apparent signs of gestation or parturition. exploratory laparotomy was used to identify a rupture of the left uterine horn and the presence of cystic endometrial hyperplasia and pyometra. two mummified papyraceous fetuses were observed in the abdominal cavity and had adhered to the spleen, pancreas, intestine and omentum. ovariehysterectomy and corrective surgery were performed. the patient had remained healthy after uterine rupture until a new estrous cycle and the development of pyometra. bitches that are 10 years old or more are predisposed to implantation failure, pregnancy or parturition problems and they should not be breed to avoid complications.
Incontinência urinária após gonadectomia em fêmeas caninas
Voorwald, Fabiana Azevedo;Tiosso, Caio de Faria;Toniollo, Gilson Hélio;
Ciência Rural , 2010, DOI: 10.1590/S0103-84782010000300038
Abstract: acquired urinary incontinence is a debilitating, incurable condition, prevalent in spayed bitches and rarely seen in entire bitches or males. in bitches, acquired urinary incontinence can occur anytime from one week after neutering and is associated with severe management problems. incontinence in neutered bitches can be associated with a decrease in maximal urethral closure pressure, hormonal changes and increase in the percentage of collagen in the bladder wall. it's also associated to a reduced contractility of the detrusor muscle, decrease in the magnitude of response of the bladder wall to both carbachol and eletrical field stimulation, and there are risk factors involved. the diagnosis is established based on historical findings, physical examination, laboratorial exams, urethral pressure profilometry, ultrasonography and abdominal radiographs. the medical management involves the appliance of -adrenergics agonists, oestrogens, gnrh analogues and antidepressive agents. surgical recommendation management corresponds to urethropexy, cistourethropexy, endoscopic periurethral injection and colposuspension. the better understanding a better comprehension of etiology, physiopathology, diagnosis methods and treatment could provide significant benefits considering the lack of knowledge and diagnoses of this clinical condition in brazil.
Efectos Del Proceso De Soldadura Tig En La Resistencia A Ensayos Por Fatiga Del Acero Aeronáutico Abnt 4130
Nascimento,Marcelino P; Voorwald,Herman J. C.; Gamarra-Rosado,Víctor O.;
Revista Latinoamericana de Metalurgia y Materiales , 2003,
Abstract: this study has as objective to analyses the effects of the tig welding process on structural integrity of abnt 4130 steel, widely used in welded aeronautical structures, by fatigue crack growth tests located in three different areas: base material, heat affected zone (haz) and weld pool. the specimens were made in accordance to astm 647 standard, from hot rolled plate containing 0,80 mm of thickness, which was determinate from previous studies of welded tubular structure failures of t-27 brazilian aircrafts. the tests were carried out on centre-cracked tension (cct) specimens conduced in room temperature, constant amplitude range, at a frequency of 10 hz, and load ratio r=0,1. the results obtained were associated to the microstructure and microhardness variations of the mentioned areas. it was observed that the fatigue crack located in the weld pool grew more quickly, followed for that located in haz and, finally, for that contained in the base material.
Controle reprodutivo de caninos e felinos no município de Jaboticabal. I intera o de projeto social com pesquisas científicas
Jeffrey Frederico Lui,Gilson Hélio Toniollo,Diego José Cardilli,Fabiana de Azevedo Voorwald
Revista Ciência em Extens？o , 2010,
Abstract: Introdu o: o excesso de animais das espécies canina e felina, principalmente, pode causar uma série de transtornos a popula o. Sabe-se que a esteriliza o cirúrgica é importante e atende a legisla o atual além de propiciar bem-estar animal, principalmente com qualidade de vida melhor e maior longevidade, além de evitar o nascimento de crias indesejáveis e sem condi o de sobrevivência adequada. Visando também a diminui o dos riscos com acidentes por mordeduras, arranhaduras, transmiss o de zoonoses, atropelamentos e prejuízos para a saúde pública. Objetivos: o projeto em desenvolvimento tem como objetivo a esteriliza o cirúrgica de caninos e felinos errantes ou n o como ferramenta eficiente e definitiva no controle reprodutivo destas espécies no Município de Jaboticabal. Paralelamente aos objetivos iniciais propostos, auxiliará de modo direto o desenvolvimento de trabalhos de alunos de gradua o e pós-gradua o com o fornecimento de material biológico e dados dos animais que s o submetidos à esteriliza o. Métodos: além da técnica convencional de esteriliza o por ovariohisterectomia em animais previamente submetidos ao pré-cirurgico com relaxantes musculares, analgésicos e anestésicos, trabalhos paralelos em desenvolvimento por discentes utilizam material biológico dos animais esterilizados e propiciam: a avalia o da dor pósoperatória e a resposta inflamatória sistêmica e do estresse nos animais submetidos a ovariohisterectomia por laparoscopia e método convencional, a análise histológica e morfometria do aparelho reprodutivo, a identifica o de clamidíase em felinos e identifica o de antígenos correlatos, e a imunolocaliza o e quantifica o de fatores de crescimento IGF-I e EGF em ovários e seus efeitos sobre a matura o in vitro de oócitos e avalia o nuclear, além da imunolocaliza o e quantifica o de proteínas no trato reprodutivo de cadelas submetidas à esteriliza o nas diferentes fases do ciclo estral. Resultados: no primeiro semestre do presente ano, 746 caninos e felinos foram esterilizados cirurgicamente, sendo que destes, 72% eram fêmeas. A participa o de alunos de gradua o e recém formados (estagiários) está sendo muito bem recebida, uma vez que os mesmos est o tendo a oportunidade de praticarem a arte da cirurgia supervisionados por médicos veterinários gabaritados, além da inclus o num projeto de ambito social que atende principalmente a classe social de baixa renda.
Effect of a Shot Peening Pre Treatment on the Fatigue Behaviour of Hard Chromium on Electroless Nickel Interlayer Coated AISI 4340 Aeronautical Steel
Nascimento Marcelino P.,Torres Marcelo A.S.,Souza Renato C.,Voorwald Herman J.C.
Materials Research , 2002,
Abstract: Multiple layer systems of coatings are considered to have larger resistance to crack propagation in comparison to coatings with simple layer. With regard to fatigue, it is possible to improve the resistance of a component with the application of shot peening treatment, whose compressive residual stresses delay or eliminate the initiation and propagation of fatigue cracks. The aim of this study is to analyse the effects on rotating bending fatigue behaviour of hard chromium fraction three-quarters electroless nickel multilayer system coated AISI 4340 high strength steel submitted to shot peening pre treatment. Results indicated that the interaction between the shot peening process with the multilayer system was not satisfactory, resulting in intense delamination. Fracture surface analysis by SEM was performed toward to identify the fatigue crack origin, as well as the coating-substrate delamination process.
Evaluation of shot peening on the fatigue strength of anodized Ti-6Al-4V alloy
Costa Midori Yoshikawa Pitanga,Voorwald Herman Jacobus Cornelis,Pigatin Walter Luis,Guimar？es Valdir Alves
Materials Research , 2006,
Abstract: The increasingly design requirements for modern engineering applications resulted in the development of new materials with improved mechanical properties. Low density, combined with excellent weight/strength ratio as well as corrosion resistance, make the titanium attractive for application in landing gears. Fatigue control is a fundamental parameter to be considered in the development of mechanical components. The aim of this research is to analyze the fatigue behavior of anodized Ti-6Al-4V alloy and the influence of shot peening pre treatment on the experimental data. Axial fatigue tests (R = 0.1) were performed, and a significant reduction in the fatigue strength of anodized Ti-6Al-4V was observed. The shot peening superficial treatment, which objective is to create a compressive residual stress field in the surface layers, showed efficiency to increase the fatigue life of anodized material. Experimental data were represented by S-N curves. Scanning electron microscopy technique (SEM) was used to observe crack origin sites.
SURFACE MODIFICATION OF SUGARCANE BAGASSE CELLULOSE AND ITS EFFECT ON MECHANICAL AND WATER ABSORPTION PROPERTIES OF SUGARCANE BAGASSE CELLULOSE/ HDPE COMPOSITES
Daniella Regina Mulinari,Herman J. C. Voorwald,Maria Odila H. Cioffi,George J. Rocha
BioResources , 2010,
Abstract: Cellulose fibres from sugarcane bagasse were bleached and modified by zirconium oxychloride in order to improve the mechanical properties of composites with high density polyethylene (HDPE). The mechanical properties of the composites prepared from chemically modified cellulose fibres were found to increase compared to those of bleached fibres. Tensile strengths of the composites showed a decreasing trend with increasing filler content. However, the values for the chemically modified cellulose fibres/HDPE composites at all mixing ratios were found to be higher than that of neat HDPE. Results of water immersion tests showed that the water absorption affected the mechanical properties. The fracture surfaces of the composites were recorded using scanning electron microscopy (SEM). The SEM micrographs revealed that interfacial bonding between the modified filler and the matrix was significantly improved by the fibre modification.
SUGARCANE BAGASSE PULPING AND BLEACHING: THERMAL AND CHEMICAL CHARACTERIZATION
Paulo Henrique Fernandes Pereira,Herman Cornelis Jacobus Voorwald,Maria Odila Hilário Cioffi,Daniella Regina Mullinari
BioResources , 2011,
Abstract: Cellulose fibers were isolated from sugarcane bagasse in three stages. Initially sugarcane bagasse was subjected to a pre-treatment process with hydrolyzed acid to eliminate hemicellulose. Whole cellulosic fibers thus obtained were then subjected to a two-stage delignification process and finally to a bleaching process. The chemical structure of the resulting cellulose fibers was studied by Fourier Transform Infrared (FTIR) spectroscopy. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) were used to analyze the effects of hydrolysis, delignification, and bleaching on the structure of the fibers. Two different thermal analysis techniques were used to study the bleaching cellulose fibers. These techniques confirmed that cellulose fibers were isolated from sugarcane bagasse. A future goal is to use these fibers as reinforcement elements in composites, organic-inorganic hybrid, and membranes for nanofiltration.
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