oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 4 )

2019 ( 762 )

2018 ( 988 )

2017 ( 910 )

Custom range...

Search Results: 1 - 10 of 565100 matches for " A.V. Oliveira "
All listed articles are free for downloading (OA Articles)
Page 1 /565100
Display every page Item
Elucidation on Reactions Thermodynamics and Kinetics of OFC-A of Steels  [PDF]
A.V. Adedayo
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2010, DOI: 10.4236/jmmce.2010.97043
Abstract: The basic principles of Oxyfuel cutting of metals lie in rapid high-temperature oxidation of the cut metal. Considerable proportion of the published work on the subject of oxygen cutting, the details of the oxidation reaction are overlooked or confused. Most often, physical characteristics of oxidized material is attributed to that of iron rather than iron oxide. The analysis of the oxidation reactions pertinent to Oxyfuel cutting of steels has also been majorly ignored. The oxidation process of iron and steel though similar in some respects, yet, in other aspects, show significant differences. This paper presents experimental and theoretical elucidation on reactions thermodynamics and kinetics of oxyfuel cutting processes of steel. Six 10mm metallurgy steel rods of different wt% C were flame cut using different acetylene and oxygen pressures. The composition of the steel rods used ranged from 0.16 wt% C to 0.33wt% C. Acetylene pressures used ranged from 3.45 x 10-2 N.m-2 to 5.52 x 10-2N.m-2, while oxygen pressure ranged from 2.76 x 10-1N.m-2 to 3.17 x 10-1 N.m-2. The result shows that the cutting rates decreased with carbon content of the steel as a result of reduction of iron oxide during decarburization reactions. Theoretical models of the thermodynamics and kinetics of cutting process pertinent to steels are also discussed.
Development Processes of Globular Microstructure  [PDF]
A.V. Adedayo
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2011, DOI: 10.4236/jmmce.2011.107050
Abstract: Semi solid metallurgy offers distinct advantages over other near-net-shape manufacturing processes. By this process, components are produced from slurry kept at a temperature between the solidus and the liquidus isotherms, resulting in breakdown of the dendritic structure. A new structure in which the morphology of the crystals of the primary phase is globular evolves. In this present paper, the importance of globular structure is identified. The theories of evolution of globular crystals in thixo–processing are identified and discussed.
Influence of Mould Heat Storage Capacity on Properties of Grey Iron  [PDF]
A.V. Adedayo, B. Aremo
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2011, DOI: 10.4236/jmmce.2011.104028
Abstract: Grey cast iron is characterized by presence of a large portion of its carbon in the form of graphite flakes which are observable in their microstructures. Their properties are significantly dependent on the micro-constituents of the, cast iron components. A way of controlling the microstructure of cast iron is through the controlled cooling rates during solidification. To control cooling rate, the heat storage capacity of the mould is important. This paper presents the characteristic effects of graphite flake sizes on some mechanical properties of grey cast iron. Six mould materials with heat storage capacities ranging from 1.52 kJ.m-2.K-1.s-1/2 to 2.16 kJ.m-2.K-1.s-1/2 were prepared and used to cast some grey cast iron samples whose microstructures were observed by optical microscopy. Mechanical properties of the grey iron were evaluated. The results show that the properties increased with the heat storage capacity of the mould. Also, the microstructures show a dependence on heat storage capacity of the mould.
Avalia o experimental do escoamento e da eros o num Luvissolo Háplico de Mértola: impactos da fertiliza o em pastagens Experimental evaluation of runoff and erosion in an Haplic Luvisol of Mértola: impacts of fertilization in pastures
J. C. Martins,F.P. Pires,A.V. Oliveira,A. M. Campos
Revista de Ciências Agrárias , 2007,
Abstract: Numa área experimental situada a meia encosta, na regi o de Mértola, Alentejo, com um Luvissolo Háplico (FAO, 2001) e um declive médio de 15%, procedeu-se à avalia o, de Outubro de 2001 a Junho de 2004, do escoamento de água superficial, provocado pela precipita o, e da perda de solo por eros o, em 3 ensaios designados por A (pastagem melhorada), B (pastagem semeada), ambos instalados em 1997, e D (pastagem semeada), estabelecido em 2001. A cobertura vegetal incorporava uma mistura de sementes constituída por azevém anual, panasco, algumas espécies de trevo, bisserula e serradela. Aqueles parametros foram quantificados através de pequenos talh es de eros o de 4?1 m2, com a maior dimens o no sentido do declive, sobrepostos em 6 talh es de cada um dos ensaios (3 modalidades e 2 repeti es, para cada ensaio). As 3 modalidades consideradas nos ensaios A e B foram as seguintes: 1 - Sem fertiliza o; 5 - Aduba o completa, corrigida anualmente; 7 -Fertiliza o organica com 8 t/ha de lama residual urbana (LRU), aplicada em 1997 + aduba o complementar. O ensaio D incluiu a aplica o de 3 níveis de LRU (L0 – 0, L1 – 12 e L2 – 24 t/ha, respectivamente). Em cada caixa de eros o, procedeu-se à medi o do volume de água escoado e à quantifica o de sedimentos, quando a capacidade de infiltra o de água no solo era excedida pela quantidade de precipita o ocorrida em um ou vários dias consecutivos. Nos ensaios A e B, os valores mais altos do coeficiente de escoamento referem-se à modalidade 1 sendo a situa o mais favorável correspondente à modalidade 7 do ensaio B. No ensaio D, os valores para aquele coeficiente situaram-se entre 0,07 e 0,10, para as 3 modalidades, que s o manifestamente baixos. Quanto à perda de solo, observou-se que foi a modalidade 7 dos ensaios A e B a que registou os valores mais baixos, no conjunto dos 3 anos. No ensaio D, observaram-se valores superiores aos verificados nos ensaios A e B, nos 3 anos, sendo mais elevados na modalidade sem fertiliza o. In a experimental area located in a hillside of Mértola region, Alentejo, with an Haplic Luvisol (FAO, 2001) and a mean slope of 15%, soil loss by erosion and surface runoff after rainfall occurrence were evaluated in small erosion plots, from October 2001 until June 2004, in 3 field experiments (A, B, and D) with a sown pasture mixture under different fertilization treatments. The experiments A (improved pasture) and B (sown pasture) were established in 1997, but the experiment D (sown pasture) was only installed in 2001. The sown mixture consisted of ryegrass, cocksfoot, some clover species,
Anthropological perspectives on injections: a review
Reeler,A.V;
Bulletin of the World Health Organization , 2000, DOI: 10.1590/S0042-96862000000100020
Abstract: qualitative studies from developing countries have pointed to the widespread popularity of injections. in addition to their use by formal and informal providers and traditional healers, there is now increasing evidence of the use of injections and injection equipment by lay people. epidemiological research links the large number of unsafe injections to serious bloodborne infections such as viral hepatitis b and c and acquired immunodeficiency syndrome (aids). the present article examines the reasons behind the demand for injections by consumers and the administration of unnecessary or unsafe injections by different types of provider. interventions aimed at reducing the risk of unsafe injections are discussed in relation to cultural and social factors as well as those factors associated with health systems. suggestions are made for approaches to the design of such interventions.
Chemical and Functional Properties of Complementary Food from Malted and Unmalted Acha (Digitaria exilis), Soybean (Glycine max) and Defatted Sesame Seeds (Sesamun indicuml.)
A.V. Ikujenlola
Journal of Engineering and Applied Sciences , 2012,
Abstract: Acha (Digitaria exilis), soybean (Glycine max) and sesame (Sesamun indicum L.) seeds were cleaned separately of dirt and extraneous materials. The acha grains were malted by steeping, germinating (72 h), drying (60 C, 20 h), dehulling, milling and sieving. Soybean and sesame seeds were processed into flours using standardized methods. Complementary food blends were formulated at various ratios from malted and unmalted acha, full fat soybean and defatted sesame flours. The formulations thus produced were assessed for chemical and functional properties. The results showed that the blends containing the malted acha had better functional properties with respect to the viscosity, water absorption capacity and bulk density. The viscosity was particularly low (< 2.550 Cps) which will enhance consumption by the intending infants. The inclusion of sesame flour boosted the level of protein of the blends.
Pathologic Significance of a Recurrent Nodular Goiter after the Operations on the Thyroid Gland
A.V. Menkov
Sovremennye Tehnologii v Medicine , 2011,
Abstract: The aim of the investigation is to determine the pathologic significance of a recurrent nodular goiter on the basis of the follow-up results analysis after the operations on the thyroid gland.Materials and methods. 64 patients (58 females and 6 males) aged 32—63 years (46.4±8.3 years) with a recurrent nodular goiter after the operations on the thyroid gland have been included into the study. The follow-up period was 5 years.Results. The absolute reoperation indications were revealed only in 9 patients (14.1%). They underwent thyroidectomy. A transitory unilateral laryngoparesis developed in 2 patients in a postoperative period. During the follow-up period euthyroidism persisted in patients with a recurrent nodular goiter required no operative intervention. Only 4 of 13 patients needed to take levothyroxine sodium required a substitution therapy correction. No significant increase of the node size was observed according to the ultrasonoscopy data. The average indicator of life quality corresponded to a good result (10.1±0.4 points).Conclusion. A recurrent nodular goiter after thyroid tissue preserving operations has no clinical manifestations in the majority of patients.
Method of the Autoimmune Process Development Prophylaxis at Operative Treatment of a Nodular Goiter
A.V. Menkov
Sovremennye Tehnologii v Medicine , 2010,
Abstract: Aim of investigation is a detection of the autoimmune process development prophylaxis new method effectiveness at operative treatment of a nodular goiter.Materials and methods. The results of a clinical observation of 19 patients, undergoing the extracapsular hemithyroidectomy, are analyzed. A new method of the autoimmune process prophylaxis was used in 9 cases at operative interventions.Results. There were no complications after operations. The titers of antibodies to a thyroid peroxidase in a month after operation were within the reference meaning limits in all the 9 cases.Conclusion. An infusion of a hydrocortisone acetate suspension with a hydrochloride lidocaine permits to prevent the autoimmune process development in a conserved thyroid tissue at operative interventions on occasion of a nodular goiter and decrease a probability of a postoperative hypothyrosis appearance.
THE BROWN HARE INFORMATION FIELD UNDER THE SNOW PERIOD IN THE STEPPE FORESTS
Mikheyev A.V.
Bìologì?nij Vìsnik Melìtopol?s?kogo Der?avnogo Pedagogì?nogo Universitetu ìmenì Bogdana Hmel?nic?kogo , 2011,
Abstract: On the basis of materials of field researches the characteristic of brown hare snow tracking in steppe forests ofa southeast of Ukraine were presented. The estimation of qualitative and quantitative parameters of sets of vitalactivity traces of this species as elements of an information field, and also aspects of their dynamics under variousfactors in the specified year period were carried out.
The Possibilities of Use Intraoperative Diathermic Ablation of Benign Thyroid Nodular Masses
A.V. Menkov
Sovremennye Tehnologii v Medicine , 2011,
Abstract: The purpose of the work is to study the possibilities of use intraoperative diathermic ablation (IODA) of benign nodular masses when performing surgeries on thyroid. Materials and methods. There were studied short-term and long-term results of thyroid resection using IODA of small nodes of reserved thyroid tissue in 40 patients (38 women and 2 men aged from 29 to 68 years). The cause of operation in 29 patients was trachea compression syndrome, in 11 patients — functional autonomy of a node in one of the thyroid lobes. Follow up period was 1—4 years. Results. 28 patients underwent hemithyroidectomy and IODA of small nodes of a contralateral lobe, 12 patients — hemithyroidectomy subtotal resection of a contralateral lobe and IODA of nodular masses (0.50±0.23 sm) of thyroid remain. There were no complications. 31 patients had stabile euthyroidism. Hypotheriosis developed in 9 patients, it being compensated by levothyroxine administration. According to ultrasound of thyroid remain, no relapses were revealed. Conclusion. The use of IODA in thyroid resection makes it possible to reserve clinically significant volume of thyroid tissue without any risk of recurrences, and reduce the possibility of postoperative hypotheriosis development.
Page 1 /565100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.