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Search Results: 1 - 10 of 494 matches for " extrusion "
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Very late pacemaker extrusion: A rare complication of permanent pacemaker implantation  [PDF]
Rajesh Vijayvergiya, Ram Chitlangia, Mukesh Yadav, Asif Hasan
World Journal of Cardiovascular Diseases (WJCD) , 2012, DOI: 10.4236/wjcd.2012.24053
Abstract: Pacemaker extrusion is an uncommon complication of device implantation. Mostly, it happens either beuse of infection or secondary to various mechanical factors. It usually occurs days to months after the implantation, however very late pacemaker extrusion has not been described in the literature. We present a case of 70 years old male, who had pacemaker extrusion 11 years after its implantation. The various management issues related with such patient is discussed in the article.
Optimisation of extrusion cooking conditions and characterization of rice (Oryza sativa)—Sweet potato (Ipomoea batatas) and rice-yam (Dioscorea alata) based RTE products  [PDF]
Elina Brahma Hazarika, Anjan Borah, Charu Lata Mahanta
Agricultural Sciences (AS) , 2013, DOI: 10.4236/as.2013.49B003
Abstract:  Extrusion cooking has been extensively used toproduce variety of foods like ready to eatbreakfast cereals, baby foods, snack foods, etc. Taking rice flour as the base ingredient, two locally available tuberous root vegetables, greater yam(Dioscoreaalata) and sweet potato (Ipomoeabatatas) were used in this study for the development of ready-to-eat breakfast products in asingle screw extruder. During extrusion cooking, the screw speeds ranged from 132 to 468 rpm and the barrel temperatures ranged from 103°C to 137°C. The extrudates were then analyzed for various physical and physicochemical properties. Optimization was done following ResponseSurface Methodology (RSM) using CentralComposite Design. Using screw speed, barrel temperature and feed composition as the three independent variables, the three responses taken were bulk density, expansion index and breaking strength. The optimized conditions wereused for developing 3 new products one of which alsocontained tomato pulp powder. The productswere analyzed for their physical, proximate, sensoryand antioxidant properties. There was significantcolour change in all the three samples as indicated by total colour change (ΔE). Texture analysis of the extrudate samples showed hardness values ranging from 28.68 N to 47.57 N. Amylose content was found to be 15.3% in rice-sweet potato extrudate, 14.7% in rice-yam extrudate and 18.2% in rice-sweet potato-tomato extrudate. The antioxidant profile of the extrudates studiedthrough DPPH (2,2-diphenyl-picryhydrazyl)scavenging activity and FRAP (ferric reducing antioxidant property) showed that the antioxidant

capacity in all the 3 extrudates was very low. Rice flour incorporated with sweet potato wasjudged the best on sensory evaluation. Thestudy has shown that both sweet potato and greater yam tubers can be commercially exploited for the development of ready-to-eat (RTE) products.

Effect of Extrusion Cooking of White Yam (Dioscorea rotundata) and Bambara-Nut (Vigna subterranean) Blend on Some Selected Extrudate Parameters  [PDF]
Bolanle Oluwatoyin Oluwole, Abiodun Adekunle Olapade
Food and Nutrition Sciences (FNS) , 2011, DOI: 10.4236/fns.2011.26084
Abstract: The effect of thermo-extrusion processing of white yam (Dioscorea rotundata) and bambara nut (Vigna subterranean) on some selected extrudate parameters of residence time, throughput and moisture content were investigated in this study. Both yam and bambara nut were processed into meals of 750 µm and 500 µm respectively. Extrusion was carried out following a three variable response surface methodology using a Box Behnken design. Blend of yam meal and Bambara nut meal at ratio 80:20 respectively was conditioned into 12.5, 15.0 and 17.5% moisture content (dry basis) and allowed to equilibrate for 4 h. Extrusion was carried out on a single screw extruder at 50, 60 and 70 rpm screw speed and 130oC, 140oC and 150oC barrel temperatures. The study revealed that the extrusion time varied between 13.1 and 29.7 sec, throughput varied from 13.3 to 34.4 kg/h and product moisture ranged from 11.1 to 16.8% dry basis). All investigated extrudate parameters were significantly affected (p< 0.05) by the process variables of screw speed, barrel temperature and feed moisture content, and their interactions. The results were indicative that the second order polynomial was adequate to model the dependence of the extrudate parameters of residence time, throughput and moisture content on extrusion variables of barrel temperature, feed moisture content and screw speed.
Difficulties in the Use of Ground Bacterial Cellulose (BC) as Reinforcement of Polylactid Acid (PLA) Using Melt-Mixing and Extrusion Technologies  [PDF]
Katrin Gan?, Axel Nechwatal, Katrin Frankenfeld, Kerstin Schlufter
Open Journal of Composite Materials (OJCM) , 2012, DOI: 10.4236/ojcm.2012.23011
Abstract: Bacterial cellulose (BC) was ground to make the material suitable for compounding with polylactid acid (PLA). The content of BC in PLA was changed between 5 and 20 wt%. By increasing the BC content of the composite DSC measurements showed an increase of crystallinity (χ c ). Annealing at 90?C resulted in a further increase of χ c . Analysis of the dynamic mechanical behavior showed a sharp decline of the storage module (G’) above the glass transition temperature (T g ) while such a sharp decline did not occur for annealed samples. This indicates that the stiffness of PLA even above T g can be improved by BC and annealing.
Predictability of the Consistency of Porridges Using Mixtures of Different Flours  [PDF]
Irene S. T. de Carvalho, Yvonne Granfeldt, Ann-Charlotte Eliasson, Petr Dejmek
Food and Nutrition Sciences (FNS) , 2013, DOI: 10.4236/fns.2013.49121
Abstract:

The purpose of this study was to investigate the predictability of the consistency of blended porridges based on the volume fractions of separate porridges made from orange-fleshed sweet potato, cowpea, dehulled soybean, dehulled sorghum and maize flour (dehulled, commercial and germinated). Accurate predictions could be made for 13 of the 21 blends investigated. The consistency of porridge consisting of mixtures of cowpea with orange-fleshed sweet potato, and cowpea with dehulled soybean was lower than expected, and was attributed to the different size distributions of the swollen flour particles. Blends containing germinated maize showed significantly lower consistency than expected in both porridges with starchy continuous phase and porridges with proteinaceous continuous phase. It was thus concluded that both amylolytic and proteolytic activity are of importance in the ameliorating effects of germinated maize.

Finite Element Simulation of a Doubled Process of Tube Extrusion and Wall Thickness Reduction  [PDF]
Ahmed S. M. J. Agena
World Journal of Mechanics (WJM) , 2013, DOI: 10.4236/wjm.2013.35026
Abstract:

This research deals with the forward extrusion process of tubes. In this process, a piercing process was carried out on the billet to produce the tube, followed directly by a reduction in the wall thickness. A specific geometrical shape for the piercing zone and the wall thickness reduction zone were chosen and designed. The effects of the redundant shear strain and the magnitude of the extrusion load were investigated and simulated with the finite element method using Q Form software program. Lead was used as model materials since (if the experiments were carried out at room temperature) it has the similar behavior of the steel at high temperature. The results obtained have shown that at the piercing zone, the lowest values of the extrusion load, the redundant strain, the total strain and the finite element effective strain were when a piercing tool (mandrel) of (C = 1.1) was used. While, at the die zone, the lowest values of the extrusion load, the redundant strain, the total strain was when a die of (C = 0.9) was used.

Microencapsulation of Essential Oils within Alginate: Formulation and in Vitro Evaluation of Antifungal Activity  [PDF]
E. A. Soliman, A. Y. El-Moghazy, M. S. Mohy El-Din, M. A. Massoud
Journal of Encapsulation and Adsorption Sciences (JEAS) , 2013, DOI: 10.4236/jeas.2013.31006
Abstract: Essential oils (EOs) are the volatile lipophilic components extracted from plants. Many EOs have demonstrated strong antimicrobial properties when tested in in vitro experiments. The commercial applications of these EOs require a suitable formulation constituted by biodegradable compounds that protect them from degradation and evaporation at the same time that allows for a sustained release. The objective of this study was therefore to reduce the rate of evaporation of the oil via microencapsulation. Alginate microspheres (AMSs) were prepared using emulsion extrusion method. The AMSs were hardened with a cross-linking agent, calcium chloride. The effects of the three variables: alginate concentration (0.5% - 8%), the amount of cross-linking agent (0.125% - 2%) and time of cross-linking (5 - 30 min.) on loading capacity and encapsulation efficiency (EE, %) were studied. The effect of the amount of cross-linker was significant on loading capacity (%) and EE (%). The AMSs under the optimized conditions provided loading capacity of 22% - 24% and EE of 90% - 94% based on type of EO. The antifungal activity of vapors of microencapsulated and non-microencapsulated oils were evaluated against two of pathogenic fungi species for stored grains: Aspergillus niger and Fusarium verticillioides. The optimized MSs were observed to have a sustained in vitro release profile (50% of the antifungal activity was maintained at the 8th day of the study). In conclusion, encapsulation in Ca-alginate microspheres may effectively reduce the evaporation rate of essential oils, thus increase the potential antifungal activity.


Design of an extrusion screw and solid fuel produced from coconut shell
Sathitruangsak, P.,Madhiyanon, T,Soponronnarit, S.
Songklanakarin Journal of Science and Technology , 2006,
Abstract: The objectives were to design an extrusion screw to produce biomass solid fuel in a cold extrusion process, and investigate the effects of molasses used as a selected adhesive on the physical properties of extruded products. The material employed consisted of crushed coconut shell char and coconut fiber char mixed at a ratio of 40:60. The ratios of molasses in the mixture were 10:100, 15:100 and 20:100 (by weight) and the extrusion die angles were 1.0, 1.1, 1.2, and 1.3 degrees gradation per experiment. The experimental results showed that the newly designed screw could function properly in the output range 0.75-0.90 kg/min, which is close to the design value. Regarding the molasses's effect on solid fuel properties, increasing the share of molasses was positive for both output and strength of the resulting briquettes, whereas the results of increasing die angle showed decreases in both output and strength. The compressive strength varied between 2.49-2.87 MPa in all circumstances, which was considerably higher than acceptable industrial level. Furthermore, the extruded solid fuel showed excellent resistance to impact force. Regarding energy consumption, the amount of electrical energy used in the extrusion process was insignificant, ranging between 0.040-0.079 kWh/kg.
Self-Extrusion of Unknowingly Ingested Sewing Needle through the Skin of Neck  [PDF]
Digvijay Singh Rawat, Sikandar Singh, Sudhanshu Pandey, Tarun Ojha, P. C. Verma
International Journal of Otolaryngology and Head & Neck Surgery (IJOHNS) , 2013, DOI: 10.4236/ijohns.2013.25040
Abstract: Foreign body ingestion is a common presentation but the extraluminal migration of a foreign body is rare. A 46-year-old man presented with protruded sharp swelling left side of neck, X-rays and CT scan of the neck showed a needle migrating from the pyriform fossa to the skin. Carotid angiography was also done to see the relations of foreign body with great vessels. Transcutaneous removal of foreign body was done under general anesthesia. The migrated foreign body was a sewing needle which patient unknowingly swallowed two days back. Migrated ingested foreign bodies from the upper digestive tract have the potential to cause life-threatening complications. Cases of spontaneous expulsion of ingested foreign bodies to the skin of the neck are quite rare.
Measuring and Modeling the Plasticity of Clays
Andrade, Fernando Augusto de;Al-Qureshi, Hazim Ali;Hotza, Dachamir;
Materials Research , 2010, DOI: 10.1590/S1516-14392010000300019
Abstract: the measurement of plasticity in clay bodies is crucial in order to get products free of defects and with less processing time. however, tests which simulate the behavior of the clay during processing and the mathematical modeling of some of its characteristics, particularly the plasticity, become difficult because many variables are involved and there is no consensus on the choice of method to be used. this study aimed to develop a mathematical model based on compression test to evaluate the plasticity of clays. three types of clays were studied with different levels of moisture and their indices of plasticity were also characterized by the atterberg's and pfefferkorn's methods. the experimental data were well fitted by the theoretical curves for a wide range of clay plasticity. moreover, it was possible to observe a correlation between effective stress of compression and paste moisture within each group of clay.
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