Search results for: molds

Authors: N. Behidj, K. Benyounes, T. Dahmane, A. Allem

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The aim of this study was to investigate the antimicrobial activity of flavonoids isolated from the aerial part of a medicinal plant which is Thymus inodorusby the middle agar diffusion method on following microorganisms. We have Staphylococcus aureus, Escherichia coli, Pseudomonas fluorescens, AspergillusNiger, Aspergillus fumigatus and Candida albicans. During this study, flavonoids extracted by stripping with steam are performed. The yields of flavonoids is 7.242% for the aqueous extract and 28.86% for butanol extract, 29.875% for the extract of ethyl acetate and 22.9% for the extract of di - ethyl. The evaluation of the antibacterial effect shows that the diameter of the zone of inhibition varies from one microorganism to another. The operation values obtained show that the bacterial strain P fluoresces, and 3 yeasts and molds; A. Niger, A. fumigatus and C. albicansare the most resistant. But it is noted that, S. aureus is shown more sensitive to crude extracts, the stock solution and the various dilutions. Finally for the minimum inhibitory concentration is estimated only with the crude extract of Thymus inodorus flavonoid.Indeed, these extracts inhibit the growth of Gram + bacteria at a concentration varying between 0.5% and 1%. While for bacteria to Gram -, it is limited to a concentration of 0.5%.

Keywords: antimicrobial activity, organic extracts, aqueous extracts, Thymus numidicus

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Authors: Ahmet E. Osmanlioglu

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In this study, natural bentonite was used as natural clay material and samples were taken from the Kalecik district in Ankara. In this research, bentonite is the subject of an analysis from standpoint of assessing the basic properties of engineered barriers with respect to the buffer material. Bentonite and sand mixtures were prepared for tests. Some of clay minerals give relatively higher hydraulic conductivity and lower swelling pressure. Generally, hydraulic conductivity of these type clays is lower than <10-12 m/s. The hydraulic properties of clay-sand mixtures are evaluated to design engineered barrier specifications. Hydraulic conductivities of bentonite-sand mixture were found in the range of 1.2x10-10 to 9.3x10-10 m/s. Optimum B/S mixture ratio was determined as 35% in terms of hydraulic conductivity and mechanical stability. At the second stage of this study, all samples were compacted into cylindrical shape molds (diameter: 50 mm and length: 120 mm). The strength properties of compacted mixtures were better than the compacted bentonite. In addition, the larger content of the quartz sand in the mixture has the greater thermal conductivity.

Keywords: engineered barriers, mechanical stability, clay, nuclear waste disposal

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Authors: Michael Steve Lopez Bernabe

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Political news coverage of tabloid sheets as one of the print media molds or influences public opinions and perceptions. In this study, Critical Discourse Analysis was employed to 30 political news taken from major tabloid sheets in the Philippines in order to determine the linguistics features and other features characterizing the political news in tabloids such as discursive styles, news topics or contexts, journalistic roles and news sources. The political underpinnings through framing were also explored in the study. The results revealed that the linguistics features of the news coverage include moods and modalities (morphology), passivity and transitivity, nominalization, appositives and embedding (syntax), and pre-modifications, the use of verbs and omissions (grammatical features). The discursive features were direct or indirect speech; cohesion; endophora and classifications. In terms of news sources were politicians, experts, and journalists; and the tabloid perform the journalistic roles such as an intervention, watchdog, loyal-facilitator, service, infotainment and civic. The news was also evident of different political underpinnings such as game or strategic framing, conflict framing, human interest framing, attrition of responsibility framing, morality framing, economic consequences framing and issue framing.

Keywords: critical discourse analysis, political news, applied linguistics, Philippines, tabloid sheets

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Authors: Abdulmagid A. Khattabi, Abdul Fatah M. Emhamed

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The steel alloy Introduced after becoming carbon-steel does not meet the requirements of engineering industry; and it cannot be obtained tensile strength from carbon-steel higher than (700MPa), the low alloy steel enters in a lot of heavy engineering equipment parts, molds, agricultural equipment and other industry. In addition, that may be exposed to in-service failure, which may require returned to work, to do the repairs or maintenance by one of the welding methods available. The ability of steel weld determined through palpation of the cracks, which can reduce by many ways. These ways are often expensive and difficult to implement, perhaps the control to choose the type of electrode welding user is one of the easiest and least expensive applications. It has been welding the steel low alloys high resistance by manual metal arc (MMA), and by using a set of welding electrodes which varying in chemical composition and in their prices as well and test their effect on tensile strength. Results showed that using the poles of welding, which have a high proportion of iron powder and low hydrogen. The Tensile resistance is (484MPa) and the weld joint efficiency was (56.9%), but when (OK 47.04) electrode was used the tensile strength increased to (720MPa) and the weld joint efficiency to (84.7%). Using the cheapest electrode (OK 45.00) the weld joint efficiency did not exceed (24.2%), but when using the most expensive electrode (OK 91.28) the weld joint efficiency is (38.1%).

Keywords: steel low alloys high resistance, electrodes welding, tensile test

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Authors: Salah Mohammed Al-Eid, Siddig Hussein Hamad, Fahad Mohammed Aljassas

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The effects of high hydrostatic pressure (HHP) treatments on microbial contamination, chemical and physical properties of fresh dates (Rutab stage) were studied. Khalas, Barhi and Hilali cultivars were treated at 200, 250, 300 and 350 MPa using HHP research apparatus. The objective of such treatments was to preserve fresh dates without adversely affecting its properties. Treating fresh dates at 300 MPa for 5 minutes at 40°C reduced microbial contamination in about 2.5 log cycles. Applying 250 MPa was enough to control Rutab contamination with molds, yeasts, and coliforms. Both treatments were enough to reduce Rutab microbial contamination to acceptable levels. HHP caused no significant effect on Rutab chemical properties (moisture, sugars, protein, pectin and acidity). However, a slight decrease in moisture contents due to HHP was observed. Rutab lightness (L*) significantly decreased due to the application of HHP. Only Rutab treated at 300 MPs gave lower redness (a*) values compared with an untreated sample. The effect of 300 MPa on increasing yellowness (b*) was observed for Barhi and Hilali but decreasing for Khalas. The hardness of all Rutab cultivars significantly decreased as a result of HHP application. In fact, the pressure applied at 300 MPa had an adverse effect on texture, which may limit its suitability for use in Rutab preservation.

Keywords: high hydrostatic pressure, fresh dates (Rutab), microbial contamination, color, texture

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Authors: Evelyne Nguegwouo, Raoul Fonkem Sonfack Tsakem, Abel Wade, Gabriel Nama Medoua, Kamgaing Theophile

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Fresh and smoked fish are widely consumed in Cameroon. The traditional nature of smoking, the lack of hygiene in production, the poor preservation of stocks and the long storage time for certain types of fish considerably favor the contamination of products by molds, which secrete toxic molecules called mycotoxins. Today there are more than 400 types of mycotoxins, Aflatoxins being the most formidable. These toxins are considered carcinogenic in humans. It is in this perspective that we proposed to evaluate the total Aflatoxins in the fish marketed and consumed by the populations of the city of Yaoundé in Cameroon. On the one hand, it was a question of conducting a survey of fish consumers and sellers in points of sale, sampling fish of three species [Marquereau (Scomber scombrus), Cod (Gadus morhua) and Bifaka (Ethmalosa fimbriata)], randomly in some markets of the city to evaluate the total Aflatoxins contents (B1, B2, G1, G2) by the quantitative ELISA method and finally to estimate the level of exposure of the populations. It emerges from this study that of the 30 samples analyzed, 96.1% contained total Aflatoxins and two samples had total Aflatoxins levels above the standard, which is 20 ppb. These first results show that the risk is present in Cameroon and in order to improve the quality of marketed fish in terms of mycotoxins, a more thorough control must be done from the production chain to the consumer.

Keywords: aflatoxins, evaluation, exposure, mycotoxins, fish

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Authors: Changyong Liu, Junda Tong, Feng Xu, Ninggui Huang

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In the injection molding process, the performance of cooling channels is crucial to the part quality. Through the application of conformal cooling channels fabricated via metal additive manufacturing, part distortion, warpage can be greatly reduced and cycle time can be greatly shortened. However, the properties of additively manufactured conformal cooling channels are quite different from conventional drilling processes such as the poorer dimensional accuracy and larger surface roughness. These features have significant influences on its cooling performance. In this study, test molds with the cooling channel diameters of φ2 mm, φ3 mm and φ4 mm were fabricated via selective laser melting and conventional drilling process respectively. A test system was designed and manufactured to measure the pressure difference between the channel inlet and outlet, the coolant flow rate and the temperature variation during the heating process. It was found that the cooling performance of SLM-fabricated channels was poorer than drilled cooling channels due to the smaller sectional area of cooling channels resulted from the low dimensional accuracy and the unmolten particles adhered to the channel surface. Theoretical models were established to determine the friction factor and heat transfer coefficient of SLM-fabricated cooling channels. These findings may provide guidance to the design of conformal cooling channels.

Keywords: conformal cooling channels, selective laser melting, cooling performance, injection molding

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Authors: Frantisek Kopriva, Kamila Michalkova, Radim Dudek, Jana Volejnikova

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Rationale: Diagnostic criteria of asthma–COPD overlap syndrome (ACOS) are controversial in pediatrics. Emphysema is characteristic of COPD and usually does not occur in typical asthma; its presence in patients with asthma suggests the concurrence with COPD. Low-dose chest computed tomography (CT) allows a non-invasive assessment of the lung tissue structure. Here we present CT findings of emphysematous changes in a child with ACOS. Patient and Methods: In a 6-year-old boy, atopy was confirmed by a skin prick test using common allergen extracts (grass and tree pollen, house dust mite, molds, cat, dog; manufacturer Stallergenes Greer, London, UK), where reactions over 3 mm were considered positive. Treatment with corticosteroids was started during the course of severe asthma. At 12 years of age, his spirometric parameters deteriorated despite treatment adjustment (VC 1.76 L=85%, FEV1 1.13 L=67%, TI%VCmax 64%, MEF25 19%, TLC 144%) and the bronchodilator test became negative. Results: Low-dose chest CT displayed irregular regions with increased radiolucency of pulmonary parenchyma (typical for hyperinflation in emphysematous changes) in both lungs. This was in accordance with the results of spirometric examination. Conclusions: ACOS is infrequent in children. However, low-dose chest CT scan can be considered to confirm this diagnosis or eliminate other diagnoses when the clinical condition is deteriorating and treatment response is poor.

Keywords: child, asthma, low-dose chest CT, ACOS

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Authors: Rupinder Kaur, Parmjit S. Panesar, Ram S. Singh

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Whey is the lactose rich by-product of the dairy industry, having good amount of nutrient reservoir. Most abundant nutrients are lactose, soluble proteins, lipids and mineral salts. Disposing of whey by most of milk plants which do not have proper pre-treatment system is the major issue. As a result of which, there can be significant loss of potential food and energy source. Thus, whey has been explored as the substrate for the synthesis of different value added products such as enzymes. β-galactosidase is one of the important enzymes and has become the major focus of research due to its ability to catalyze both hydrolytic as well as transgalactosylation reaction simultaneously. The enzyme is widely used in dairy industry as it catalyzes the transformation of lactose to glucose and galactose, making it suitable for the lactose intolerant people. The enzyme is intracellular in both bacteria and yeast, whereas for molds, it has an extracellular location. The present work was carried to utilize the whey for the production of β-galactosidase enzyme using both yeast and fungal cultures. The yeast isolate Kluyveromyces marxianus WIG2 and various fungal strains have been used in the present study. Different disruption techniques have also been investigated for the extraction of the enzyme produced intracellularly from yeast cells. Among the different methods tested for the disruption of yeast cells, SDS-chloroform showed the maximum β-galactosidase activity. In case of the tested fungal cultures, Aureobasidium pullulans NCIM 1050, was observed to be the maximum extracellular enzyme producer.

Keywords: β-galactosidase, fungus, yeast, whey

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Authors: Liubov Magerramova, Eugene Kratt, Pavel Presniakov

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A detailed analysis has been performed for several schemes of Gas Turbine Wheels production based on additive and powder technologies including metal, ceramic, and stereolithography 3-D printing. During the process of development and debugging of gas turbine engine components, different versions of these components must be manufactured and tested. Cooled blades of the turbine are among of these components. They are usually produced by traditional casting methods. This method requires long and costly design and manufacture of casting molds. Moreover, traditional manufacturing methods limit the design possibilities of complex critical parts of engine, so capabilities of Powder Metallurgy Techniques (PMT) were analyzed to manufacture the turbine wheel with air-cooled blades. PMT dramatically reduce time needed for such production and allow creating new complex design solutions aimed at improving the technical characteristics of the engine: improving fuel efficiency and environmental performance, increasing reliability, and reducing weight. To accelerate and simplify the blades manufacturing process, several options based on additive technologies were used. The options were implemented in the form of various casting equipment for the manufacturing of blades. Methods of powder metallurgy were applied for connecting the blades with the disc. The optimal production scheme and a set of technologies for the manufacturing of blades and turbine wheel and other parts of the engine can be selected on the basis of the options considered.

Keywords: additive technologies, gas turbine engine, powder technology, turbine wheel

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Authors: Nilgun Kuskonmaz

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Ceramic molding can produce castings with fine detail, smooth surface and high degree of dimensional accuracy. All these features are the key factors for producing decorated glass moulds. In the ceramic mold casting process, the fundamental parameters affecting the mold-metal reactions are the composition and the properties of the refractory materials used in the production of ceramic mold. As a result of the reactions taking place between the liquid metal and mold surface, it is not possible to achieve a perfect surface quality, a fine surface detail and maintain a high standard dimensional tolerances. The present research examines the effects of the binder composition on the structural and physical properties of the zircon ceramic mold. In the experiment, the ceramic slurry was prepared by mixing the refractory powders (zircon(ZrSiO4), mullit(3Al2O32SiO2) and alumina (Al2O3)) with the low alkaline silica (ethyl silicate (C8H20O4Si)) and acidic type gelling material suitable binder and gelling agent. This was followed by pouring that ceramic slurry on to a silicon pattern. After being gelled, the mold was removed from the silicon pattern and dried. Then, the ceramic mold was subjected to the reaction sintering at 1600°C for 2 hours in the furnace. The stainless steel (SS) was cast into the sintered ceramic mold. At the end of this process it was observed that the surface quality of decorated glass mold.

Keywords: ceramic mold, stainless steel casting, decorated glass mold

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Authors: Roxana Gheorghita, Gheorghe Gutt

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Environmental pollution due to non-degradation of packaging from the food and pharmaceutical industry is reaching increasingly alarming levels. The packaging used for food supplements is usually composed of successive layers of synthetic materials, conventional, glue, and paint. The situation is becoming more and more problematic as the population, according to statistics, uses food supplements more and more often. The solution can be represented by edible packaging, completely biodegradable, and compostable. The tested materials were obtained from biopolymers, agar, carrageenan, and alginate, in well-established quantities and plasticized with glycerol. Rosemary, thyme, and oregano essential oils have been added in varying proportions. The obtained films are completely water-soluble in hot liquids (with a temperature of about 80° C) and can be consumed with the product contained. The films were glossy, pleasant to the touch, thin (thicknesses between 32.8 and 52.8 μm), transparent, and with a pleasant smell, specific to the added essential oil. Tested for microbial evaluation, none of the films indicated the presence of E. coli, S. aureus, enterobacteria, coliform bacteria, yeasts, or molds. This aspect can also be helped by the low values of the water activity index (located between 0.546 and 0.576). The mechanical properties indicated that the material became more resistant with the addition of essential oil, the best values being recorded by the addition of oregano. The results obtained indicate the possibility of using biopolymer-based films with the addition of rosemary, thyme, and oregano essential oil, for wrapping food supplements, thus replacing conventional packaging, multilayer, impossible to sort and recycle.

Keywords: edible films, food supplements, oregano, rosemary, thyme

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Authors: Bita Mohajernia, R. J. Urbanic

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Mold making techniques have focused on meeting the customers’ functional and process requirements; however, today, molds are increasing in size and sophistication, and are difficult to manufacture, transport, and set up due to their size and mass. Presently, mold weight saving techniques focus on pockets to reduce the mass of the mold, but the overall size is still large, which introduces costs related to the stock material purchase, processing time for process planning, machining and validation, and excess waste materials. Reducing the overall size of the mold is desirable for many reasons, but the functional requirements, tool life, and durability cannot be compromised in the process. It is proposed to use Finite Element Analysis simulation tools to model the forces, and pressures to determine where the material can be removed. The potential results of this project will reduce manufacturing costs. In this study, a light weight structure is defined by an optimal distribution of material to carry external loads. The optimization objective of this research is to determine methods to provide the optimum layout for the mold structure. The topology optimization method is utilized to improve structural stiffness while decreasing the weight using the OptiStruct software. The optimized CAD model is compared with the primary geometry of the mold from the NX software. Results of optimization show an 8% weight reduction while the actual performance of the optimized structure, validated by physical testing, is similar to the original structure.

Keywords: finite element analysis, plastic injection molding, topology optimization, weight reduction

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Authors: Dina Kuttah

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It is well known that recycling of by-product materials saves natural resources, reduces by-product volumes, and reduces the need for virgin materials. The steel industry produces a myriad of metal components for industrial chains, which in turn generates mineral discarded sand molds. Although these sands are clean before their use, after casting, they may contain contaminants. Therefore, huge quantities of excess by-product foundry sand (BFS) end up occupying large volumes in landfills. In Sweden, approximately 200000 tonnes of excess BFS end up in landfills. The transportation and construction industries have the greatest potential for reuse by-products because they use vast quantities of earthen materials annually. Accordingly, experimental work has been undertaken to evaluate the possible use of two chosen BFS from two Swedish foundries in a conventional Swedish asphalt mixture. The experimental procedure of this research has focused on the dosage, environmental and technical properties of the same mixture type ABT 11 and the same bitumen (160/220) but at different replacement proportions of the conventional fine sand with the two BFS. The environmental requirements, in addition to the technical requirements, namely, void ratio, static indirect tensile strength ratio, and resilient modulus before and after moisture-induced sensitivity tests of the asphalt mixtures, have been investigated in the current study. The test results demonstrated that the BFS from both foundries can be incorporated in the selected asphalt mixture at specified replacement proportions of the conventional fine sand fraction 0-2 mm, as discussed in the paper.

Keywords: asphalt mixtures, by-product foundry sand, indirect tensile strength, moisture induced sensitivity tests, resilient modulus

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Authors: Layal Karam, Rayan Roustom, Mohamad G. Abiad, Tahra El-Obeid, Ioannis N. Savvaidis

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The demand for marinated chicken worldwide, is continuously growing. To date, limited data on addition of active components of Essential Oils (EOs) to marinades for chicken preservation are available. The antimicrobial effect of carvacrol and thymol, added at 0.4 and 0.8% v/w to marinated fresh chicken, stored in air and under vacuum packaging (VP), for 21 days at 4°C, was examined. The samples were monitored for microbiological (total viable count (TVC), lactic acid bacteria (LAB), Brochothrix thermosphacta, Pseudomonas spp., total coliforms, Escherichia coli, yeasts and molds) and sensory attributes (odor characteristics). Our data supports that among the tested microorganisms, Pseudomonas spp., LAB and B. thermosphacta were the most dominant microbiota in the marinated chicken samples. Additionally, the use of active EOs components, especially the higher concentration (0.8% v/w) in combination with VP, retarded the growth of spoilage microbiota and resulted in a significant reduction of about 2.9-3.1 log cfu/g and a microbiological shelf-life extension of marinated chicken by > 6 days, as judged by TVC data. Interestingly, the combination of active components of EOs at the lower concentration (0.4% v/w) and packaging (air or vacuum) resulted in a significant sensorial shelf-life extension of 15 and >21 days, as compared to the controls’ shelf-life of 9 days. The results of our study demonstrated the potential of the active components, carvacrol and thymol, as natural effective antimicrobial hurdles to control the growth of spoilage microorganisms in marinated chicken meat.

Keywords: chicken, essential oils compounds, marination, meat spoilage, preservation

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Authors: Adeshina Fadeyibi

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Application of pure thermoplastic film in food packaging is greatly limited because of its poor service performance, often enhanced by the addition of organic or inorganic particles in the range of 1–100 nm. Thus, this study was conducted to develop cassava starch zinc-nanocomposite films for applications in food packaging. Three blending ratios of 1000 g cassava starch, 45–55 % (w/w) glycerol and 0–2 % (w/w) zinc nanoparticles were formulated, mixed and mechanically homogenized to form the nanocomposite. Thermoplastic were prepared, from a dispersed mixture of 24 g of the nanocomposite and 600 ml of distilled water, and heated to 90oC for 30 minutes. Plastic molds of 350 ×180 mm dimension and 8, 10 and 12 mm depths were used for film casting and drying at 60oC and 80 % RH for 24 hour. The average thicknesses of the dried films were found to be 15, 16 and 17 µm. The films were characterized based on their barrier, thermal, mechanical and structural properties. The results show that the oxygen and water vapor barrier properties increased with glycerol concentration and decreased with thickness; but the full width at half maximum (FWHM) and d- spacing increased with thickness. The higher degree of d- spacing obtained is a consequence of higher polymer intercalation and exfoliation. Also, only 2 % weight degradation was observed when the films were exposed to temperature between 30–60oC; indicating that they are thermally stable and can be used for packaging applications in the tropics. The mechanical properties of the film were higher than that of the pure thermoplastic but comparable with the LDPE films. The information on the characterized attributes and optimization of the cassava starch zinc-nanocomposite films justifies their alternative application to pure thermoplastic and conventional films for food packaging.

Keywords: synthesis, characterization, casaava Starch, nanocomposite film, packaging

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Authors: C. Malça, P. Gonçalves, N. Alves, A. Mateus

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Regardless of the manufacturing process used, subtractive or additive, material, purpose and application, produced components are conventionally solid mass with more or less complex shape depending on the production technology selected. Aspects such as reducing the weight of components, associated with the low volume of material required and the almost non-existent material waste, speed and flexibility of production and, primarily, a high mechanical strength combined with high structural performance, are competitive advantages in any industrial sector, from automotive, molds, aviation, aerospace, construction, pharmaceuticals, medicine and more recently in human tissue engineering. Such features, properties and functionalities are attained in metal components produced using the additive technique of Rapid Prototyping from metal powders commonly known as Selective Laser Melting (SLM), with optimized internal topologies and varying densities. In order to produce components with high strength and high structural and functional performance, regardless of the type of application, three different internal topologies were developed and analyzed using numerical computational tools. The developed topologies were numerically submitted to mechanical compression and four point bending testing. Finite Element Analysis results demonstrate how different internal topologies can contribute to improve mechanical properties, even with a high degree of porosity relatively to fully dense components. Results are very promising not only from the point of view of mechanical resistance, but especially through the achievement of considerable variation in density without loss of structural and functional high performance.

Keywords: additive manufacturing, internal topologies, porosity, rapid prototyping, selective laser melting

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Authors: Adebola Ajayi, Francis B. Aiyeleye, Olakunke M. Makanjuola, Olalekan J. Adebowale

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Cocoyam, a generic term for both xanthoma and colocasia, is a traditional staple root crop in many developing countries in Africa, Asia and the Pacific. It is mostly cultivated as food crop which is very rich in vitamin B6, magnesium and also in dietary fiber. The cocoyam starch is easily digested and often used for baby food. Drying food is a method of food preservation that removes enough moisture from the food so bacteria, yeast and molds cannot grow. It is a one of the oldest methods of preserving food. The effect of drying methods on the proximate composition and functional properties of extracted cocoyam starch flour were studied. Freshly harvested cocoyam cultivars at matured level were washed with portable water, peeled, washed and grated. The starch in the grated cocoyam was extracted, dried using sun drying, oven and cabinet dryers. The extracted starch flour was milled into flour using Apex mill and packed and sealed in low-density polyethylene film (LDPE) 75 micron thickness with Nylon sealing machine QN5-3200HI and kept for three months under ambient temperature before analysis. The result showed that the moisture content, ash, crude fiber, fat, protein and carbohydrate ranged from 6.28% to 12.8% 2.32% to 3.2%, 0.89% to 2.24%%, 1.89% to 2.91%, 7.30% to 10.2% and 69% to 83% respectively. The functional properties of the cocoyam starch flour ranged from 2.65ml/g to 4.84ml/g water absorption capacity, 1.95ml/g to 3.12ml/g oil absorption capacity, 0.66ml/g to 7.82ml/g bulk density and 3.82% to 5.30ml/g swelling capacity. Significant difference (P≥0.5) was not obtained across the various drying methods used. The drying methods provide extension to the shelf-life of the extracted cocoyam starch flour.

Keywords: cocoyam, extraction, oven dryer, cabinet dryer

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Authors: Susana P. Dias, Andrea Gomes, Fernanda M. Ferreira, Marta F. Henriques

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Thymus mastichina L. is an endogenous medicinal and aromatic plant of the Mediterranean flora. It has been used empirically over the years as a natural preservative in food. Nowadays, the antimicrobial activity of its bioactive compounds, such as essential oils and extracts, has been well recognized. The main purpose of this study was to evaluate the antimicrobial effect of Thymus mastichina ethanolic and aqueous extracts on pathogens and spoilage microorganisms present in cheese during ripening. The effect that the extract type and its concentration has on the development of Staphylococcus aureus, Escherichia coli, and Yarrowia lipolytica populations during 24 hours, was studied 'in vitro' using appropriate culture media. The results achieved evidenced the antimicrobial activity of T. mastichina extracts against the studied strains, and the concentration of 2 mg/mL (w/v) was selected and used directly on the cheese surface during ripening. In addition to the microbiological evaluation in terms of total aerobic bacteria, Enterobacteriaceae, yeasts (particularly Y. lipolytica) and molds, the treated cheeses physicochemical evaluation (humidity, aw, pH, colour, and texture) was also performed. The results were compared with cheeses with natamicyn (positive control) and without any treatment (negative control). The physicochemical evaluation showed that the cheeses treated with ethanolic extract of Thymus mastichina, except the fact that they lead to a faster water loss during ripening, did not present considerable differences when compared to controls. The study revealed an evident antimicrobial power of the extracts, although less effective than the one shown by the use of natamycin. For this reason, the improvement of the extraction methods and the adjustment of the extract concentrations will contribute to the use of T. mastichina as a healthier and eco-friendly alternative to natamycin, that is also more attractive from an economic point of view.

Keywords: antimicrobial activity, cheese, ethanolic extract, Thymus mastichina

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Authors: Magdalena Twaruzek, Karolina Ropejko

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Mycotoxins are secondary metabolites of molds. Ochratoxin A (OTA) is the most common in the Polish climate. It is produced by fungi of the genera Aspergillus and Penicillium. It is produced as a result of improper food storage. It is present in many products that are consumed both by humans and animals: cereals, wheat gluten, coffee, dried fruit, wine, grape juice, spices, beer, and products based on them. OTA is nephrotoxic, hepatotoxic, potentially carcinogenic, and teratogenic. OTA mainly enters an organism by oral intake. The aim of the study was to detect the presence of OTA in milk, urine, and serum of lactating women. A survey was also conducted regarding the daily diet of women. The research group consisted of 32 lactating women (11 were the donors from the Milk Bank in Toruń, the other 21 were recruited for this study). Results of the analysis showed the occurrence of OTA only in 3 milk samples (9.38%). The minimum level was 0.01 ng/ml, while the maximum 0.018 ng/ml and the mean 0.0013 ng/ml. Twenty-six urine samples (81.25%) were OTA positive, with minimum level 0.013 ng/ml, maximum level 0.117 ng/ml and mean 0.0192 ng/ml. Also, all 32 serum samples (100%) were contaminated by OTA, with a minimum level of 0.099 ng/ml, a maximum level of 2.38 ng/ml, and a mean of 0.4649 ng/ml. In the case of 3 women, OTA was present in all tested body fluids. Based on the results, the following conclusions can be drawn: the breast-milk of women in the study group is slightly contaminated with ochratoxin A. Ten samples of urine contained ochratoxin A above its average content in tested samples. Moreover, serum of 8 women contains ochratoxin A at a level above the average content of this mycotoxin in tested samples. The average ochratoxin A level in serum in the presented studies was 0.4649 ng/ml, which is much lower than the average serum ochratoxin A level established in several countries in the world, i.e., 0.7 ng/ml. Acknowledgment: This study was supported by the Polish Minister of Science and Higher Education under the program 'Regional Initiative of Excellence' in 2019 - 2022 (Grant No. 008/RID/2018/19).

Keywords: breast-milk, urine, serum, contamination, ochratoxin A

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Authors: Michail Milas, Aikaterini Dafni Tegiou, Nickolas Rigopoulos, Eustathios Giaouris, Zaharias Loannou

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Nanotechnology, a relatively new scientific field, addresses the manipulation of nanoscale materials and devices, which are governed by unique properties, and is applied in a wide range of industries, including food packaging. The incorporation of nanoparticles into polymer matrices used for food packaging is a field that is highly researched today. One such combination is silver nanoparticles with polypropylene. In the present study, the synthesis of the silver nanoparticles was carried out by a natural method. In particular, a ripe banana peel extract was used. This method is superior to others as it stands out for its environmental friendliness, high efficiency and low-cost requirement. In particular, a 1.75 mM AgNO₃ silver nitrate solution was used, as well as a BPE concentration of 1.7% v/v, an incubation period of 48 hours at 70°C and a pH of 4.3 and after its preparation, the polypropylene films were soaked in it. For the PP films, random PP spheres were melted at 170-190°C into molds with 0.8cm diameter. This polymer was chosen as it is suitable for plastic parts and reusable plastic containers of various types that are intended to come into contact with food without compromising its quality and safety. The antimicrobial test against Escherichia coli DFSNB1 and Staphylococcus epidermidis DFSNB4 was performed on the films. It appeared that the films with silver nanoparticles had a reduction, at least 100 times, compared to those without silver nanoparticles, in both strains. The limit of detection is the lower limit of the vertical error lines in the presence of nanoparticles, which is 3.11. The main reasons that led to the adsorption of nanoparticles are the porous nature of polypropylene and the adsorption capacity of nanoparticles on the surface of the films due to hydrophobic-hydrophilic forces. The most significant parameters that contributed to the results of the experiment include the following: the stage of ripening of the banana during the preparation of the plant extract, the temperature and residence time of the nanoparticle solution in the oven, the residence time of the polypropylene films in the nanoparticle solution, the number of nanoparticles inoculated on the films and, finally, the time these stayed in the refrigerator so that they could dry and be ready for antimicrobial treatment.

Keywords: antimicrobial control, banana peel extract, E. coli, natural synthesis, microbe, plant extract, polypropylene films, S.epidermidis, silver nano, random pp

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Authors: Mehdi Shekarbeigi

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The consolidation of loose substrates as well as substrate layers through promoting stabilizing materials is one of the most commonly used road construction techniques. Cement, lime, and flax, as well as asphalt emulsion, are common materials used for soil stabilization to enhance the soil’s strength and durability properties. Cement could be simply used to stabilize permeable materials such as sand in a relatively short time threshold. In this research, typical Portland cement is selected for the stabilization of isotropic sand; the effect of static and cyclic loading on the behavior of these soils has been examined with various percentages of Portland cement. Thus, firstly, a soil’s general features are investigated, and then static tests, including direct cutting, density and single axis tests, and California Bearing Ratio, are performed on the samples. After that, the dynamic behavior of cement on silica sand with the same grain size is analyzed. These experiments are conducted on cement samples of 3, 6, and 9 of the same rates and ineffective limiting pressures of 0 to 1200 kPa with 200 kPa steps of the face according to American Society for Testing and Materials D 3999 standards. Also, to test the effect of temperature on molds and frost samples, 0, 5, 10, and 20 are carried out during 0, 5, 10, and 20-second periods. Results of the static tests showed that increasing the cement percentage increases the soil density and shear strength. The single-axis compressive strength increase is higher for samples with higher cement content and lower densities. The results also illustrate the relationship between single-axial compressive strength and cement weight parameters. Results of the dynamic experiments indicate that increasing the number of loading cycles and melting and freezing cycles enhances permeability and decreases the applied pressure. According to the results of this research, it could be stated that samples containing 9% cement have the highest amount of shear modulus and, therefore, decrease the permeability of soil. This amount could be considered as the optimal amount. Also, the enhancement of effective limited pressure from 400 to 800kPa increased the shear modulus of the sample by an average of 20 to 30 percent in small strains.

Keywords: cement, isotropic sands, static load, three-axis cycle, melting and freezing cycles

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Authors: E. Hovad, J. H. Walther, P. Larsen, J. Thorborg, J. H. Hattel

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In sand casting of metal parts for the automotive industry such as brake disks and engine blocks, the molten metal is poured into a sand mold to get its final shape. The DISAMATIC molding process is a way to construct these sand molds for casting of steel parts and in the present work numerical simulations of this process are presented. During the process green sand is blown into a chamber and subsequently squeezed to finally obtain the sand mould. The sand flow is modelled with the Discrete Element method (DEM) and obtaining the correct material parameters for the simulation is the main goal. Different tests will be used to find or calibrate the DEM parameters needed; Poisson ratio, Young modulus, rolling friction coefficient, sliding friction coefficient and coefficient of restitution (COR). The Young modulus and Poisson ratio are found from compression tests of the bulk material and subsequently used in the DEM model according to the Hertz-Mindlin model. The main focus will be on calibrating the rolling resistance and sliding friction in the DEM model with respect to the behavior of “real” sand piles. More specifically, the surface profile of the “real” sand pile will be compared to the sand pile predicted with the DEM for different values of the rolling and sliding friction coefficients. When the DEM parameters are found for the particle-particle (sand-sand) interaction, the particle-wall interaction parameter values are also found. Here the sliding coefficient will be found from experiments and the rolling resistance is investigated by comparing with observations of how the green sand interacts with the chamber wall during experiments and the DEM simulations will be calibrated accordingly. The coefficient of restitution will be tested with different values in the DEM simulations and compared to video footages of the DISAMATIC process. Energy dissipation will be investigated in these simulations for different particle sizes and coefficient of restitution, where scaling laws will be considered to relate the energy dissipation for these parameters. Finally, the found parameter values are used in the overall discrete element model and compared to the video footage of the DISAMATIC process.

Keywords: discrete element method, physical properties of materials, calibration, granular flow

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Authors: Shunyi Yang, Jingjing Yan, Siyu Dong, Xiangguo Cui

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Current architectural façade design practices incorporate various daylighting and solar radiation analysis methods. These emphasize the impact of geometry on façade design. There is scope to extend this knowledge into methods that address material translucency, porosity, and form. Such approaches can also achieve these conditions through adaptive robotic manufacturing approaches that exploit material dynamics within the design, and alleviate fabrication waste from molds, ultimately accelerating the autonomous manufacturing system. Besides analyzing the environmental solar radiant in building facade design, there is also a vacancy research area of how lighting effects can be precisely controlled by engaging the instant real-time data-driven robot control and manipulating the material properties. Ceramics carries a wide range of transmittance and deformation potentials for robotics control with the research of its material property. This paper presents one semi-autonomous system that engages with real-time data-driven robotics control, hardware kit design, environmental building studies, human interaction, and exploratory research and experiments. Our objectives are to investigate the relationship between different clay bodies or ceramics’ physio-material properties and their transmittance; to explore the feedback system of instant lighting data in robotic fabrication to achieve precise lighting effect; to design the sufficient end effector and robot behaviors for different stages of deformation. We experiment with architectural clay, as the material of the façade that is potentially translucent at a certain stage can respond to light. Studying the relationship between form, material properties, and porosity can help create different interior and exterior light effects and provide façade solutions for specific architectural functions. The key idea is to maximize the utilization of in-progress robotics fabrication and ceramics materiality to create a highly integrated autonomous system for lighting facade design and manufacture.

Keywords: light transmittance, data-driven fabrication, computational design, computer vision, gamification for manufacturing

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Authors: Ibrahim Siddig Hamid, Ikram Mohamed Eltayeb

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Trachyspermum ammi belongs to the family Apiaceae, is used traditionally for the treatment of gastrointestinal ailments, lack of appetite and bronchial problems as well used as antiseptic, antimicrobial, antipyretic, febrifugal and in the treatment of typhoid fever. Peganum harmala belongs to the family Zygophyllaceae it has been reported to have an antibacterial activity and used to treat depression and recurring fevers. It also used to kill algae, bacteria, intestinal parasites and molds. In Sudan, the combination of two plants are traditionally used for the treatment of bacillary dysentery. Bacillary dysentery is caused by one or more types of Shigella species bacteria mainly Shigella dysenteri and shigella flexneri. Bacillary dysentery is mainly found in hot countries like Sudan with poor hygiene and sanitation. Bacillary dysentery causes sudden onset of high fever and chills, abdominal pain, cramps and bloating, urgency to pass stool, weight loss, and dehydration and if left untreated it can lead to serious complications including delirium, convulsions and coma. A serious infection like this can be fatal within 24 hours. The objective of this study is to investigate the in vitro susceptibility of Sh. flexneri and Sh. dysenteriae to the T. ammi and P. harmala. T. ammi and P. harmala were extracted by 96% ethanol using Soxhlet apparatus. The antimicrobial activity of the extracts was investigated according to the disc diffusion method. The discs were prepared by soaking sterilized filter paper discs in 20 microliter of serially diluted solutions of each plant extract with the concentrations (100, 50, 25, 12.5, 6.25mg/dl) then placing them on Muller Hinton Agar plates that were inoculated with bacterial suspension separately, the plates were incubated for 24 hours at 37c and the minimum inhibitory concentration of the extract which was the least concentration of the extract to inhibit fungal growth was determined. The results showed the high antimicrobial activity of T. ammi extract with an average diameter zone ranging from 18-20 mm and its minimum inhibitory concentration was found to be 25 mg/ml against the two shigella species. P. harmala extract was found to have slight antibacterial effect against the two bacteria. This result justified the Sudanese traditional use of Trachyspermum ammi plant for the treatment of bacillary dysentery.

Keywords: harmala, peganum, shigella, trachyspermum

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Authors: Nikoloz Jalabadze, Roin Chedia, Lili Nadaraia, Levan Khundadze

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Nanocrystalline materials in powder condition can be manufactured by a number of different methods, however manufacture of composite materials product in the same nanocrystalline state is still a problem because the processes of compaction and synthesis of nanocrystalline powders go with intensive growth of particles – the process which promotes formation of pieces in an ordinary crystalline state instead of being crystallized in the desirable nanocrystalline state. To date spark plasma sintering (SPS) has been considered as the most promising and energy efficient method for producing dense bodies of composite materials. An advantage of the SPS method in comparison with other methods is mainly low temperature and short time of the sintering procedure. That finally gives an opportunity to obtain dense material with nanocrystalline structure. Graphene has recently garnered significant interest as a reinforcing phase in composite materials because of its excellent electrical, thermal and mechanical properties. Graphene nanoplatelets (GNPs) in particular have attracted much interest as reinforcements for ceramic matrix composites (mostly in Al2O3, Si3N4, TiO2, ZrB2 a. c.). SPS has been shown to fully densify a variety of ceramic systems effectively including Al2O3 and often with improvements in mechanical and functional behavior. Alumina consolidated by SPS has been shown to have superior hardness, fracture toughness, plasticity and optical translucency compared to conventionally processed alumina. Knowledge of how GNPs influence sintering behavior is important to effectively process and manufacture process. In this study, the effects of GNPs on the SPS processing of Al2O3 are investigated by systematically varying sintering temperature, holding time and pressure. Our experiments showed that SPS process is also appropriate for the synthesis of nanocrystalline powders of alumina-graphene composites. Depending on the size of the molds, it is possible to obtain different amount of nanopowders. Investigation of the structure, physical-chemical, mechanical and performance properties of the elaborated composite materials was performed. The results of this study provide a fundamental understanding of the effects of GNP on sintering behavior, thereby providing a foundation for future optimization of the processing of these promising nanocomposite systems.

Keywords: alumina oxide, ceramic matrix composites, graphene nanoplatelets, spark-plasma sintering

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Authors: Shegufta Zahan, Muhammad A. Zahin, Muhammad M. Hossain, Raquib Ahsan

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Rice Husk Ash (RHA) is one of the agricultural waste byproducts available widely in the world and contains a large amount of silica. In Bangladesh, stones cannot be used as coarse aggregate in infrastructure works as they are not available and need to be imported from abroad. As a result, bricks are mostly used as coarse aggregates in concrete as they are cheaper and easily produced here. Clay is the raw material for producing brick. Due to rapid urban growth and the industrial revolution, demand for brick is increasing, which led to a decrease in the topsoil. This study aims to produce lightweight block aggregates with sufficient strength utilizing RHA at low cost and use them as an ingredient of concrete. RHA, because of its pozzolanic behavior, can be utilized to produce better quality block aggregates at lower cost, replacing clay content in the bricks. The whole study can be divided into three parts. In the first part, characterization tests on RHA and clay were performed to determine their properties. Six different types of RHA from different mills were characterized by XRD and SEM analysis. Their fineness was determined by conducting a fineness test. The result of XRD confirmed the amorphous state of RHA. The characterization test for clay identifies the sample as “silty clay” with a specific gravity of 2.59 and 14% optimum moisture content. In the second part, blocks were produced with six different types of RHA with different combinations by volume with clay. Then mixtures were manually compacted in molds before subjecting them to oven drying at 120 °C for 7 days. After that, dried blocks were placed in a furnace at 1200 °C to produce ultimate blocks. Loss on ignition test, apparent density test, crushing strength test, efflorescence test, and absorption test were conducted on the blocks to compare their performance with the bricks. For 40% of RHA, the crushing strength result was found 60 MPa, where crushing strength for brick was observed 48.1 MPa. In the third part, the crushed blocks were used as coarse aggregate in concrete cylinders and compared them with brick concrete cylinders. Specimens were cured for 7 days and 28 days. The highest compressive strength of block cylinders for 7 days curing was calculated as 26.1 MPa, whereas, for 28 days curing, it was found 34 MPa. On the other hand, for brick cylinders, the value of compressing strength of 7 days and 28 days curing was observed as 20 MPa and 30 MPa, respectively. These research findings can help with the increasing demand for topsoil of the earth, and also turn a waste product into a valuable one.

Keywords: characterization, furnace, pozzolanic behavior, rice husk ash

Procedia PDF Downloads 75

Authors: Muhammad Farhan Saeed, Waheed Aslam Khan, Muhammad Nadeem, Iftikhar Ahmad, Zakir Ali

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Milk is an important and fundamental nutrition source of human diet. In Pakistan, the milk used by the consumer is of low quality and is often contaminated due to the lack of quality controls. Mycotoxins produced from molds which contaminate the agriculture commodities of animal feed. Mycotoxins are poisons which affect the animals when they consume contaminated feeds. Aflatoxin AFM1 is naturally occurring form of mycotoxins in milk which is carcinogenic. To assess public awareness regarding milk Aflatoxin contamination, a population-based survey using a questionnaire was carried out from general public and from farmers of both rural and urban areas. It was revealed from the data that people of rural area were more satisfied about quality of available milk but the awareness level about milk contamination was found lower in both areas. Total 297 samples of milk were collected from rural (n=156) and urban (n=141) areas of district Vehari during June-July 2015. Milk samples were collected from three different point sources; farmer, milkman and milkshop. These point sources had three types of dairy milk including cow milk, buffalo milk and mixed milk. After performing ELISA test 18 samples with positive ELISA results were maintain per source for further analysis for aflatoxin M1 (AFM1) by High Performance Liquid Chromatography (HPLC). Higher percentages of samples were found exceeding the permissible limit for urban area. In rural area about 15% samples and from urban area about 35% samples were exceeded the permissible limit of AFM1 with 0.05µg/kg set by European Union. From urban areas about 55% of buffalo, 33% of cows and 17% of mixed milk samples were exceeded the permissible AFM1 level as compared with 17%, 11% and 17% for milk samples from rural areas respectively. Samples from urban areas 33%, 44% and 28% were exceeded the permissible AFM1 level for farmer, milkman and of milk shop respectively as compared with 28% and 17% of farmer and milkman’s samples from rural areas respectively. The presence of AFM1 in milk samples demands the implementation of strict regulations and also urges the need for continuous monitoring of milk and milk products in order to minimize the health hazards. Regulations regarding aflatoxins contamination and adulteration should be strictly imposed to prevent health problems related to milk quality. Permissible limits for aflatoxin should be enforced strongly in Pakistan so that economic loss due to aflatoxin contamination can be reduced.

Keywords: Vehari, aflatoxins AFM1, milk, HPLC

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Authors: Cecile Meier, Drago Diaz Aleman, Itahisa Perez Conesa, Jose Luis Saorin Perez, Jorge De La Torre Cantero

Abstract:

In this work, two ways of creating small-sized metal sculptures are proposed: the first by means of microcasting and the second by electroforming from models printed in 3D using an FDM (Fused Deposition Modeling‎) printer or using a DLP (Digital Light Processing) printer. It is viable to replace the wax in the processes of the artistic foundry with 3D printed objects. In this technique, the digital models are manufactured with resin using a low-cost 3D FDM printer in polylactic acid (PLA). This material is used, because its properties make it a viable substitute to wax, within the processes of artistic casting with the technique of lost wax through Ceramic Shell casting. This technique consists of covering a sculpture of wax or in this case PLA with several layers of thermoresistant material. This material is heated to melt the PLA, obtaining an empty mold that is later filled with the molten metal. It is verified that the PLA models reduce the cost and time compared with the hand modeling of the wax. In addition, one can manufacture parts with 3D printing that are not possible to create with manual techniques. However, the sculptures created with this technique have a size limit. The problem is that when printed pieces with PLA are very small, they lose detail, and the laminar texture hides the shape of the piece. DLP type printer allows obtaining more detailed and smaller pieces than the FDM. Such small models are quite difficult and complex to melt using the lost wax technique of Ceramic Shell casting. But, as an alternative, there are microcasting and electroforming, which are specialized in creating small metal pieces such as jewelry ones. The microcasting is a variant of the lost wax that consists of introducing the model in a cylinder in which the refractory material is also poured. The molds are heated in an oven to melt the model and cook them. Finally, the metal is poured into the still hot cylinders that rotate in a machine at high speed to properly distribute all the metal. Because microcasting requires expensive material and machinery to melt a piece of metal, electroforming is an alternative for this process. The electroforming uses models in different materials; for this study, micro-sculptures printed in 3D are used. These are subjected to an electroforming bath that covers the pieces with a very thin layer of metal. This work will investigate the recommended size to use 3D printers, both with PLA and resin and first tests are being done to validate use the electroforming process of microsculptures, which are printed in resin using a DLP printer.

Keywords: sculptures, DLP 3D printer, microcasting, electroforming, fused deposition modeling

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Authors: T. I. Mbata, M. J. Ikenebomeh

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Background: The study was aim at formulating a complementary foods based on maize and bambara groundnut with a view of reducing malnutrition in low income families. Protein-energy malnutrition is a major health challenge attributed to the inappropriate complementary feeding practices, low nutritional quality of traditional complementary foods and high cost of quality protein-based complementary foods. Methods: The blends 70% maize, 30% bambara groundnut were evaluated for proximate analyses, minerals, amino acids profile, and antinutritional factors, using proprietary formula (‘Nutrend’) as standard. Antinutritional factors, amino acids, microbiological properties and sensory attributes were determined using standard methods. Results; For Protein, the results were 15.0% for roasted bambara groundnut maize germinated flour (RBMGF), 13.80% for cooked bambara groundnut maize germinated flour (CBMGF), 15.18% for soaked bambara groundnut maize germinated flour (SBMGF); values for maize flour and nutrend had 10.4% and 23.21% respectively. With respect to energy value, RBMGF, CBMGF, SBMGF, maize flour and nutrend had 494.9, 327.58, 356.49, 366.8 and 467.2 kcal respectively. The percentages of total essential amino acids in the composition of the blends were 36.9%, 40.7% and 38.9% for CBMGF, SBMGF and RBMGF, respectively, non-essential amino acids contents were 63.1%, 59.3% and 61.1% for CBMGF, SBMGF and RBMGF respectively. The mineral content, that is, calcium, potassium, magnesium and sodium, of formulated samples were higher than those obtained for maize flour and Nutrend. The antinutrient composition of RBMGF and CBMGF were lower than of SBMGF. The rats fed with the control diet exhibited better growth performance such as feed intake (1527 g) and body weight gain (93.8 g). For the microbial status, microflora gradually changed from gram negative enteric bacteria, molds, lactic acid bacteria and yeast to be dominated by gram positive lactic acid bacteria (LAB) and yeasts. Yeasts and LAB growth counts in the complementary food varied between 4.44 and 7.36 log cfu/ml. LAB number increased from 5.40 to 7.36 log cfu/ml during fermentation. Yeasts increased from 4.44 to 5.60 log cfu/ml. Organoleptic evaluation revealed that the foods were well accepted. Conclusion: Based on the findings the application of bambara groundnut fortification to traditional foods can promote the nutritional quality of African maize - based traditional foods with acceptable rheological and cooking qualities.

Keywords: bambara groundnut, maize, fortification, complementary food

Procedia PDF Downloads 330