Search results for: casting mold

Authors: Uchegbu Nneka Nkechi, Okoye Ogochukwu Peace

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The evaluation of the visco-elastic properties and microbial quality of a formulated oat-based dietetic food were investigated. Oat flour, pumpkin seed flour, carrot flour and skimmed milk powder were blended in varying proportions to formulate a product with codes OCF, which contains 70% oat flour, 10 % carrot flour, 10 % pumpkin seed flour and 10% skimmed milk powder, OCF which contains 65 % oat flour, 10 % carrot flour, 10 % pumpkin seed flour and 15 % skimmed milk powder, OCF which contains 60 % oat flour, 10 % carrot flour, 10 % pumpkin seed flour and 20 % skimmed milk powder, OCF which contains 55 % oat flour, 10 % carrot flour, 10 % pumpkin seed flour and 25 % skimmed milk powder and OF with 95 % oat as the commercial control. All the samples were assessed for their proximate composition, microbial quality and visco-elastic properties. The moisture content was highest at sample OF (10.73%) and lowest at OCF (7.10%) (P<0.05). Crude protein ranged from 13.38%-22.86%, with OCF having the highest (P<0.05) protein content and OF having the lowest. Crude fat was 3.74% for OCF and 6.31% for OF. Crude fiber ranged from 3.58% - 17.39% with OF having the lowest (P<0.05) fiber content and OCF having the highest. Ash content was 1.30% for OCF and 2.75% for OCF. There was no mold growth in the samples. The total viable ml/wl count ranged from 1.5×10³ cfu/g - 2.6×10³ cfu/g, with OCF having the lowest and OF having the highest (P<0.05) total viable count. The peak viscosity of the sample ranged from 75.00 cP-2895.00 cP, with OCF having the lowest and OF having the highest value. The final viscosity was 130.50 cP in OCF and 3572.50 cP in OF. The setback viscosity was 58.00 cP in OCF and 1680.50 cP in OF. The peak time was 6.93 mins in OCF to 5.57 mins in OF. There was no pasting temperature for all samples except the OF, which had 86.43. Sample OF was the highest in terms of overall acceptability. This study showed that the oat-based composite flour produced had a nutritional profile that would be acceptable for the aged population.

Keywords: dietetic, pumpkin, visco-elastic, microbial

Procedia PDF Downloads 197

Authors: Nanjiang Chen

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In the backdrop of expanding urban landscapes, accurately assessing spatial openness is critical. Traditional visibility analysis methods grapple with discretization errors and inefficiencies, creating a gap in truly capturing the human experi-ence of space. Addressing these gaps, this paper introduces a distinct continuous visibility algorithm, a leap in measuring urban spaces from a human-centric per-spective. This study presents a methodological breakthrough by applying this algorithm to urban visibility analysis. Unlike conventional approaches, this tech-nique allows for a continuous range of visibility assessment, closely mirroring hu-man visual perception. By eliminating the need for predefined subdivisions in ray casting, it offers a more accurate and efficient tool for urban planners and architects. The proposed algorithm not only reduces computational errors but also demonstrates faster processing capabilities, validated through a case study in Bei-jing's urban setting. Its key distinction lies in its potential to benefit a broad spec-trum of stakeholders, ranging from urban developers to public policymakers, aid-ing in the creation of urban spaces that prioritize visual openness and quality of life. This advancement in urban analysis methods could lead to more inclusive, comfortable, and well-integrated urban environments, enhancing the spatial experience for communities worldwide.

Keywords: visual openness, spatial continuity, ray-tracing algorithms, urban computation

Procedia PDF Downloads 50

Authors: Kubra Dogan, Fatih Tornuk

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Due to increasing consumer demand for the high-quality food products and awareness regarding the health benefits of different nutrients in food minimal processing becomes more popular in modern food preservation. To date, heat treatment is often used for inactivation of spoilage microorganisms in foods. However, it may cause significant changes in the quality and nutritional properties of food. In order to overcome the detrimental effects of heat treatment, several alternatives of non-thermal microbial inactivation processes have been investigated. Ultraviolet (UV) inactivation is a promising and feasible method for better quality and longer shelf life as an alternative to heat treatment, which aims to inhibit spoilage and pathogenic microorganisms and to inactivate the enzymes in vegetable juice production. UV-C is a sub-class of UV treatment which shows the highest microcidal effect between 250-270 nm. The wavelength of 254 nm is used for the surface disinfection of certain liquid food products such as vegetable juice. Effects of UV-C treatment on microbiological load and quality parameter of vegetable juice which is a mix of celery, carrot, lemon and orange was investigated. Our results showed that storing of UV-C applied vegetable juice for three months, reduced the count of TMAB by 3.5 log cfu/g and yeast-mold by 2 log cfu/g compared to control sample. Total phenolic content was found to be 514.3 ± 0.6 mg gallic acid equivalent/L, and there wasn’t a significant difference compared to control. The present work suggests that UV-C treatment is an alternative method for disinfection of vegetable juice since it enables adequate microbial inactivation, longer shelf life and has minimal effect on degradation of quality parameters of vegetable juice.

Keywords: heat treatment, phenolic content, shelf life, ultraviolet (UV-C), vegetable juice

Procedia PDF Downloads 210

Authors: Ammar Neshati, Elham Hamidi Shishavan

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Statement of Problem: The increase in the use of metal-ceramic restorations and a high prevalence of porcelain chipping entails introducing an alloy which is more compatible with porcelain and which causes a stronger bond between the two. This study is to compare shear bond strength of three base-metal alloys and one noble alloy with the common VMK Master Porcelain. Materials and Method: Three different groups of base-metal alloys (Ni-cr-T3, Super Cast, Verabond) and one group of noble alloy (x-33) were selected. The number of alloys in each group was 15. All the groups went through the casting process and change from wax pattern into metal disks. Then, VMK Master Porcelain was fired on each group. All the specimens were put in the UTM and a shear force was loaded until a fracture occurred. The fracture force was then recorded by the machine. The data was subjected to SPSS Version 16 and One-Way ANOVA was run to compare shear strength between the groups. Furthermore, the groups were compared two by two through running Tukey test. Results: The findings of this study revealed that shear bond strength of Ni-Cr-T3 alloy was higher than the three other alloys (94 Mpa or 330 N). Super Cast alloy had the second greatest shear bond strength (80. 87 Mpa or 283.87 N). Both Verabond (69.66 Mpa or 245 N) and x-33 alloys (66.53 Mpa or 234 N) took the third place. Conclusion: Ni-Cr-T3 with VMK Master Porcelain has the greatest shear bond strength. Therefore, the use of this low-cost alloy is recommended in metal-ceramic restorations.

Keywords: shear bond, base-metal alloy, noble alloy, porcelain

Procedia PDF Downloads 489

Authors: Shidrokh Goudarzi, Wan Haslina Hassan

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Heterogeneous wireless networks are converging towards an all-IP network as part of the so-called next-generation network. In this paradigm, different access technologies need to be interconnected; thus, vertical handovers or vertical handoffs are necessary for seamless mobility. In this paper, we conduct a review of existing vertical handover decision-making mechanisms that aim to provide ubiquitous connectivity to mobile users. To offer a systematic comparison, we categorize these vertical handover measurement and decision structures based on their respective methodology and parameters. Subsequently, we analyze several vertical handover approaches in the literature and compare them according to their advantages and weaknesses. The paper compares the algorithms based on the network selection methods, complexity of the technologies used and efficiency in order to introduce our vertical handover decision framework. We find that vertical handovers on heterogeneous wireless networks suffer from the lack of a standard and efficient method to satisfy both user and network quality of service requirements at different levels including architectural, decision-making and protocols. Also, the consolidation of network terminal, cross-layer information, multi packet casting and intelligent network selection algorithm appears to be an optimum solution for achieving seamless service continuity in order to facilitate seamless connectivity.

Keywords: heterogeneous wireless networks, vertical handovers, vertical handover metric, decision-making algorithms

Procedia PDF Downloads 395

Authors: Mustafa Abu Ghalia, Yaser Dahman

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A new class of polyurethane (PU) reinforced with green bacterial cellulose nanofibers (BC) were prepared using a solvent casting method, with the goal of fabricating green nanocomposites. Four series classes of BC (1, 2.5, 5, and 10 wt%) were reinforced into PU matrices via BC surface modification and subsequently BC-grafted into PU throughout silane coupling agent to improve BC dispersion and its interfacial interaction. The experiment results from the tensile tester were evaluated according to the response surface method (RSM) for optimizing the impacts of variable parameters, pore size, porosity, and BC contents on the mechanical properties. The compressive strength for PU-5 BC wt% was about 9.8 MPa, and decrease when being generated prosperity to recorded at 4.9 MPa. Nielson model was applied to investigate the BC stress concentration on the PU matrices. Likewise, krenche and Hapli-Tasi model were employed to evaluate the BC nanofiber reinforcement potential and BC orientation into PU matrices. The analysis of variance (ANOVA) demonstrated that only BC loading has a significant effect in increases tensile strength, young’s modulus, and a flexural modulus of the PU-BC nanocomposites. The optimal factors of the variables experiment confirmed to be 5 wt% for BC, 230 for pore size, and 80 % for porosity. Scanning electron microscopy (SEM) micrographs showed that the uniform distribution of nanofibers in the PU matrices with the addition of BC 5 wt %. Hydrolytic degradation revealed that the weight loss in PU-BC scaffold is higher than PU-BC wt %.

Keywords: polyurethane scaffold, mechanical properties, tissue engineering, polyurethane

Procedia PDF Downloads 207

Authors: Khaled Suleiman Mohammed Al-Mashrafi

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A compositional plume is a fluid flow in a directional channel of finite width in another fluid of different material composition. The study of the dynamics of compositional plumes plays an essential role in many real-life applications like industrial applications (e.g., iron casting), environmental applications (e.g., salt fingers and sea ice), and geophysical applications (e.g., solidification at the inner core boundary (ICB) of the Earth, and mantle plumes). The dynamics of compositional plumes have been investigated experimentally and theoretically. The experimental works observed that the plume flow seems to be stable, although some experiments showed that it can be unstable. At the same time, the theoretical investigations showed that the plume flow is unstable. This is found to be true even if the plume is subject to rotation or/and in the presence of a magnetic field and even if another plume of different composition is also present. It is noticeable that all the theoretical studies on the dynamics of compositional plumes are conducted in unbounded domains. The present work is to investigate theoretically the influence of vertical walls (boundaries) on the dynamics of compositional plumes in the absence/presence of a rotation field. The mathematical model of the dynamics of compositional plumes used the equations of continuity, motion, heat, concentration of light material, and state. It is found that the presence of boundaries has a strong influence on the basic state solution as well as the stability of the plume, particularly when the plume is close to the boundary, but the compositional plume remains unstable.

Keywords: compositional plumes, stability, bounded domain, vertical boundaries

Procedia PDF Downloads 34

Authors: Mustafa Col, Funda Gul Koc, Merve Yangaz, Eylem Subasi, Can Akbasoglu

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G38NiCrMo8-4-4 steel is widely used in mining industries, machine parts, gears due to its high strength and toughness properties. In this study, microstructure, wear and mechanical properties of G38NiCrMo8-4-4 steel modified with boron used in the mining industry were investigated. For this purpose, cast materials were alloyed by melting in an induction furnace to include boron with the rates of 0 ppm, 15 ppm, and 50 ppm (wt.) and were formed in the dimensions of 150x200x150 mm by casting into the sand mould. Homogenization heat treatment was applied to the specimens at 1150˚C for 7 hours. Then all specimens were austenitized at 930˚C for 1 hour, quenched in the polymer solution and tempered at 650˚C for 1 hour. Microstructures of the specimens were investigated by using light microscope and SEM to determine the effect of boron and heat treatment conditions. Changes in microstructure properties and material hardness were obtained due to increasing boron content and heat treatment conditions after microstructure investigations and hardness tests. Wear tests were carried out using a pin-on-disc tribometer under dry sliding conditions. Charpy V notch impact test was performed to determine the toughness properties of the specimens. Fracture and worn surfaces were investigated with scanning electron microscope (SEM). The results show that boron element has a positive effect on the hardness and wear properties of G38NiCrMo8-4-4 steel.

Keywords: G38NiCrMo8-4-4 steel, boron, heat treatment, microstructure, wear, mechanical properties

Procedia PDF Downloads 196

Authors: Bahar Basturk, Secil Celik Erbas, Sevket Can Sarikaya

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Composites combining the particulates and polymer components have attracted great interest in various application areas such as packaging, furniture, electronics and automotive industries. For strengthening the plastic matrices, the utilization of natural fillers instead of traditional reinforcement materials has received increased attention. The properties of natural filler based polymer composites (NFPC) may be improved by applying proper surface modification techniques to the powder phase of the structures. In this study, acorn powder-epoxy and pine corn powder-epoxy composites containing up to 45% weight percent particulates were prepared by casting method. Alkali treatment and acetylation techniques were carried out to the natural particulates for investigating their influences under mechanical forces. The effects of filler type and content on the tensile properties of the composites were compared with neat epoxy. According to the quasi-static tensile tests, the pine cone based composites showed slightly higher rigidity and strength properties compared to the acorn reinforced samples. Furthermore, the structures independent of powder type and surface modification technique, showed higher tensile properties with increasing the particle content.

Keywords: natural fillers, polymer composites, surface modifications, tensile properties

Procedia PDF Downloads 469

Authors: Anthony El Hachem, Hosam Salman

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Selecting the most effective construction method for drilled shafts under the high phreatic surface can be a challenging task that requires effective communication between the design and construction teams. Slurry placement, temporary casing, and permanent casing are the three most commonly used installation techniques to ensure the stability of the drilled hole before casting the concrete. Each one of these methods has its implications on the installation and performance of the drilled piers. Drilled shafts were designed to support a fire wall for an Energy project in Central Texas. The subsurface consisted of interlayers of sands and clays of varying shear strengths. The design recommended that the shafts be installed with temporary casing or slurry displacement due to the anticipated groundwater seepage through granular soils. During the foundation construction, it was very difficult to maintain the stability of the hole, and the contractor requested to install the shafts using permanent casings. Therefore, the foundation design was modified to ensure that the cased shafts achieve the required load capacity. Effective and continuous communications between the owner, contractor and design team during field shaft installations to mitigate the unforeseen challenges helped the team to successfully complete the project.

Keywords: construction challenges, deep foundations, drilled shafts, loose sands underwater table, permanent casing

Procedia PDF Downloads 194

Authors: K. Maliki, A. Ajayi, O. M. Makanjuola, O. J. Adebowale

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Cocoyam is herbaceous perennial plant which belongs to the family Araceae and genus xanthosoma or cococasia is mostly cultivated as food crop. It is very rich in Vitamin B6, Magnesium and also in dietary fiber. Matured cocoyam is eaten boiled, Fried or roasted in Nigeria. It can also be dried and used to make flour. Food drying is a method of food preservation in which food is dried, thus inhibit the growth of bacteria yeast and mold through the removal of water. Drying effect on the proximate composition and functional properties of cocoyam flour were investigated. Freshly harvested cocoyam cultivars at matured level were washed with portable water, peeled, sliced into 0.3mm thickness blanch in boiling water at 100°C for 15 minutes and dried using sun drying oven and cabinet dryers. The blanched slices were divided into three lots and were subjected to different drying methods. The dried cocoyam slices were milled into flour using Apex mill and packed into Low Density Polyethylene Film (LDPE) 75 Micron 4 thickness and kept for four months under ambient temperature before analysis. The results showed that the moisture content, ash, crude fiber, fat, protein and carbohydrate ranged from 7.35% to 13.89%, 1.45% to 3.3%, 1.2% to 3.41%, 2.1% to 3.1%, 6.30% to 9.1% and 66% to 82% respectively. The functional properties of the cocoyam flour ranged from 1. 65ml/g to 4.24ml/g water absorption capacity, 0.85ml/g to 2.11ml/g oil absorption capacity 0.56ml/g and 0.78ml/g bulk density and 4.91% to 6.80% swelling capacity. The result showed that there was not significant difference (P ≥ 0.5) across the various drying methods used. Cabinet drying method was found to have the best quality characteristic values than the other drying methods. In conclusion, drying of cocoyam could be used for value addition and provide extension to shelf-life.

Keywords: cocoyam flour, drying, cabinet dryer, oven dryer

Procedia PDF Downloads 248

Authors: Rezzouq Asiya, Bouftou Abderrahim, Belfadil Doha, Taoufyk Azzeddine, El Bouchti Mehdi, Zyade Souad, Cherkaoui Omar, Majid Sanaa

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Plastic packaging is widely used, but its pollution is a major environmental problem. Solutions require new sustainable technologies, environmental management, and the use of bio-based polymers as sustainable packaging. Cellulose acetate (CA) is a biobased polymer used in a variety of applications such as the manufacture of plastic films, textiles, and filters. However, it has limitations in terms of thermal stability and rigidity, which necessitates the addition of plasticizers to optimize its use in packaging. Plasticizers are molecules that increase the flexibility of polymers, but their influence on the chemical and physical properties of films (CA) has not been studied in detail. Some studies have focused on mechanical and thermal properties. However, an in-depth analysis is needed to understand the interactions between the additives and the polymer matrix. In this study, the aim is to examine the effect of two types of plasticizers, glycerol (a conventional plasticizer) and an ionic liquid, on the transparency, mechanical, thermal and barrier properties of cellulose acetate (CA) films prepared by the solution-casting method . Various analytical techniques were used to characterize these films, including infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), water vapor permeability (WVP), oxygen permeability, scanning electron microscopy (SEM), opacity, transmission analysis and mechanical tests.

Keywords: cellulose acetate, plasticizers, biopolymers, ionic liquid, glycerol.

Procedia PDF Downloads 40

Authors: Asmaa Selim, Peter Mizsey

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Bio-ethanol is considered of higher potential as a green renewable energy source owing to its environmental benefits and its high efficiency. In the present study, silver nanoparticles were in-situ generated in a poly (vinyl alcohol) in order to improve its potentials for pervaporation of ethanol-water mixture using solution-casting. Effect of silver content on the pervaporation separation index and the enrichment factor of the membrane at 15 percentage mass water at 40ᵒC was reported. Pervaporation data for nanocomposite membranes showed around 100% increase in the water permeance values while the intrinsic selectivity decreased. The water permeances of origin crosslinked PVA membrane, and the 2.5% silver loaded PVA membrane are 26.65 and 70.45 (g/m².kPa.h) respectively. The values of total flux and water flux are closed to each other, indicating that membranes could be effectively used to break the azeotropic point of ethanol-water. Effect of temperature on the pervaporation performance, permeation parameter and diffusion coefficient of both water and ethanol was discussed. The negative heat of sorption ∆Hs values calculated on the basis of the estimated Arrhenius activation energy values indicating that the sorption process was controlled by Langmuir’s mode. The overall results showed that the membrane containing 0.5 mass percentage of Ag salt exhibited excellent PV performance.

Keywords: bio-ethanol, diffusion coefficient, nanocomposite, pervaporation, poly (vinyl alcohol), silver nanoparticles

Procedia PDF Downloads 171

Authors: Seyed Reza Aghili, Tahereh Shokohi, Lotfollah Davoodi, Zahra Kashi, Azam Moslemi, Mahdi Abastabar, Iman Haghani, Sabah Mayahi, Asoudeh A.

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Introduction: In diabetic foot ulcers, if fungal agents such as Candida species penetrate into the cutaneous or depth of ulcer, can increase the degree of the wound and cause Candia infection and make it more difficult to heal. Material & Methods: A cross-sectional study was performed on 100 diabetic foot ulcer patients in 2020 in Sari, Iran. patient's data and wound grade were recorded in a questionnaire. Candida infection was diagnosed with direct microscopic examination and culture of samples. Colony-PCR molecular method was used for ITS region of DNA and then PCR-RFLP with Msp1 enzyme and using HWP1 specific gene to determine species of Candida agent. Results: Of 100 patients, the mean age 62.1 ± 10.8 years, 95% type 2 diabetes, 83%>10 years duration diabetes, 59% male, 66%> poor education level, 99% married, 52% rural, 95% neuropathic symptoms, 88% using antibiotics, 69%HbA1C >9%, and mean ulcer degree 2.6±1.05 were. Candida infection was seen in 13% of the deep tissue of the wound and 7% cutaneous around the wound. The predominant Candida isolated was C. parapsilosis (71.5%), C .albicans (14.3%). Fungal infections caused by mold fungi were not detected. There was a statistically significant relationship between yeast infection and gender, rural, HbA1C and ulcer degree. Conclusion: Mycological evaluations often are ignored. Candida parapsilosis is the most common infectious agent in these patients and may require specific treatment. Therefore, more attention of physicians to Candida infections particularly, early diagnosis and effective treatment can help faster recovery and prevent amputation.

Keywords: diabetic foot ulcer, candida infection, risk factors, c. parapsilosis

Procedia PDF Downloads 196

Authors: Marilia M. Camargo, Luisa A. Gachet-Barbosa, Rosa C. C. Lintz

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The addition of fibers into concrete matrix can enhance some properties of the composite, such as tensile, flexural and impact strengths, toughness, deformation capacity and post-cracking ductility. Many factors affect the mechanical behavior of fiber reinforced concrete, such as concrete matrix (concrete strength, additions, aggregate diameter, etc.), characteristics of the fiber (geometry, type, aspect ratio, volume, orientation, distribution, strength, stiffness, etc.), specimen (size, geometry, method of preparation and loading rate). This research investigates the effects of fiber volume and orientation on the post-cracking behavior of steel fiber reinforced concrete (SFRC). Hooked-end steel fibers with aspect ratios of 45 were added into concrete with volume of 0,32%, 0,64%, 0,94%. The post-cracking behaviour was assessed by double punch test of cubic specimens and the actual volume and orientation of the fibers were determined by non-destructive tests by means of electromagnetic induction. The results showed that the actual volume of fibers in each sample differs in a small amount from the dosed volume of fibers and that the deformation and toughness of the concrete increase with the increase in the actual volume of fibers. In determining the orientation of the fibers, it was found that they tend to distribute more in the X and Y axes due to the influence of the walls of the mold. In addition, it was concluded that the orientation of the fibers is important in the post-cracking behaviour of FRC when analyzed together with the actual volume of fibers, since the greater the volume of fibers, the greater the number of fibers oriented orthogonally to the application of loadings and, consequently, there is a better mechanical behavior of the composite. These results provide a better understanding of the influence of volume and fiber orientation on the post-cracking behavior of the FRC.

Keywords: fiber reinforced concrete, steel fibers, volume of fibers, orientation of fibers, post-cracking behaviour

Procedia PDF Downloads 181

Authors: Rahul R. Gurpude, Pallvita Yadav, Amrut Mulay

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In recent years, there has been a growing focus on advanced manufacturing processes, and one such emerging process is wire electric discharge machining (WEDM). WEDM is a precision machining process specifically designed for cutting electrically conductive materials with exceptional accuracy. It achieves material removal from the workpiece metal through spark erosion facilitated by electricity. Initially developed as a method for precision machining of hard materials, WEDM has witnessed significant advancements in recent times, with numerous studies and techniques based on electrical discharge phenomena being proposed. These research efforts and methods in the field of ED encompass a wide range of applications, including mirror-like finish machining, surface modification of mold dies, machining of insulating materials, and manufacturing of micro products. WEDM has particularly found extensive usage in the high-precision machining of complex workpieces that possess varying hardness and intricate shapes. During the cutting process, a wire with a diameter ranging from 0.18mm is employed. The evaluation of EDM performance typically revolves around two critical factors: material removal rate (MRR) and surface roughness (SR). To comprehensively assess the impact of machining parameters on the quality characteristics of EDM, an Analysis of Variance (ANOVA) was conducted. This statistical analysis aimed to determine the significance of various machining parameters and their relative contributions in controlling the response of the EDM process. By undertaking this analysis, optimal levels of machining parameters were identified to achieve desirable material removal rates and surface roughness.

Keywords: WEDM, MRR, optimization, surface roughness

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Authors: Muna K. Abbass, Laith A. Mohammed, Muntaha K. Abbas

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The oxidation of Al-Li base alloy containing small amounts of rare earth (RE) oxides such as 0.2 wt% Y2O3 and 0.2wt% Nd2O3 particles have been studied at temperatures: 400ºC, 500ºC and 550°C for 60hr in a dry air. Alloys used in this study were prepared by melting and casting in a permanent steel mould under controlled atmosphere. Identification of oxidation kinetics was carried out by using weight gain/surface area (∆W/A) measurements while scanning electron microscopy (SEM) and x-ray diffraction analysis were used for micro structural morphologies and phase identification of the oxide scales. It was observed that the oxidation kinetic for all studied alloys follows the parabolic law in most experimental tests under the different oxidation temperatures. It was also found that the alloy containing 0.2 wt %Y 2O3 particles possess the lowest oxidation rate and shows great improvements in oxidation resistance compared to the alloy containing 0.2 wt % Nd2O3 particles and Al-Li base alloy. In this work, Taguchi method is performed to estimate the optimum weight gain /area (∆W/A) parameter in oxidation process of Al-Li base alloys to obtain a minimum thickness of oxidation layer. Taguchi method is used to formulate the experimental layout, to analyses the effect of each parameter (time, temperature and alloy type) on the oxidation generation and to predict the optimal choice for each parameter and analyzed the effect of these parameters on the weight gain /area (∆W/A) parameter. The analysis shows that, the temperature significantly affects on the (∆W/A) parameter.

Keywords: Al-Li base alloy, oxidation, Taguchi method, temperature

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Authors: Hyunuk Kim, Yang No Yun, Muhammad Sohail, Jong-Ho Moon, Young Cheol Park

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Metal-organic frameworks (MOFs), which are emerging absorbents assembled from metal ions and organic ligands, have attracted attention for their permanent porosity and design of tunable pore size. These microporous materials showed interesting properties for CO₂ storage and separation. In particular, MOFs with high surface area and open metal sites showed the remarkable adsorption capacity and selectivity for CO₂. [Mg₂ (DOBDC)] (DOBDC = 2,5-dioxidobenzene-1,4-dicarboxylate) (MOF-74 or CPO-27) is a well-known absorbent showing an exceptionally high CO₂ sorption capacity at low partial pressure and room temperature. In this work, we synthesized [M₂(DOBDC)(DMF)₂] (M = Mg, Co, Ni) and determined their single-crystal structures by X-ray crystallography. The removal of coordinated guest molecules generates Lewis acidic sites and showed high CO₂ adsorption affinity. Both CO₂ adsorption capacity and surface area are much higher than reported values in literature. To fabricate MMMs, microcrystalline [M₂ (DOBDC)(DMF)₂] was synthesized by microwave reaction and dispersed in PDMS solution. The MMMs with a various amount of [M₂ (DOBDC)(DMF) ₂] in PDMS were fabricated by a solution casting method. [M₂ (DOBDC)(DMF)₂]@PDMS membrane showed higher CO2 permeability and CO₂/N₂ selectivity than those of PDMS. Therefore, we believe that MMMs combining polymer and MOFs provide new materials for CO₂ separation technology.

Keywords: metal-organic frameworks, mixed matrix membrane, CO2/N2 separation, polydimethylsiloxane (PDMS)

Procedia PDF Downloads 206

Authors: Gafar Bamigbade, Adebunkola Omemu

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“Ogi” is a fermented cereal gruel prepared from maize (Zea mays), millet (Pennisetum typhoideum) or guinea corn (Sorghum bicolour). It could be boiled to give a thicker consistency wrapped in leaf allowed to cool and set to a gel known as “eko”. The objective of this study is to determine the amylase activities of mould associated with the spoilage of Ogi and eko. Moulds were isolated from spoilt Ogi and eko samples using standard microbiological procedures. The isolate was then screened for amylase production using starch agar medium. Positive isolates were used for amylase production by solid state fermentation (SFF) using rice bran as the medium. An alpha-amylase and glucoamylase activity of the crude enzyme was determined using the DNS method. The mean mold Population ranged from 1.15 X 105cfu/g for raw Ogi to 6.25 X 105cfu/g for Eko (wrapped in Leaves). Twenty-seven (27) moulds isolated from the sample include A. niger, A. flavus, A. fumigatus, Rhizopus species and Penicillium species. Aspergillus flavus had the highest percentage (51.9%) of incidence while Penicillium species had the least (3.7%). Out of the 27 isolates screened, 19 were found to be amylase positive by showing a clear zone around their colony after flooding with iodine solution. Diameter of clear zone ranged from 3.00mm (Aspergillus niger, C4) to 22.00mm (Aspergillus flavus, A1). Aspergillus niger isolated from spoilt Eko wrapped in leaf has the highest percentage alpha-amylase activity (30.8%) and Aspergillus flavus isolated from spoilt raw ogi has the lowest activity (11.4%). Aspergillus niger isolated from spoilt Eko wrapped in nylon produces the highest glucoamylase activity (240U/ml) while penicillium specie isolated from spoilt cooked ogi has the lowest activity (100U/ml). This study shows that moulds associated with spoilage of ogi and eko can produce amylase.

Keywords: glucoamylase, alpha amylase, ogi, eko

Procedia PDF Downloads 283

Authors: Yanbing Feng, Deqing Mei, Yancheng Wang, Zichen Chen

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With the advantage of low volume density, high specific surface area, light weight and good permeability, porous aluminum material has the potential to be used in automotive, railway, chemistry and construction industries, etc. A layered powder sintering and dissolution method were developed to fabricate the porous surface Al structure with high efficiency. However, the densification mechanism during the cold compaction of laminar composite powders is still unclear. In this study, multi particle finite element modelling (MPFEM) based on the cohesive zone method (CZM) is used to simulate the cold compaction behavior of laminar Al and NaCl composite powders. To obtain its densification mechanism, the macro and micro properties of final compacts are characterized and analyzed. The robustness and accuracy of the numerical model is firstly verified by experimental results and data fitting. The results indicate that the CZM-based multi particle FEM is an effective way to simulate the compaction of the laminar powders and the fracture process of the NaCl powders. In the compaction of the laminar powders, the void is mainly filled by the particle rearrangement, plastic deformation of Al powders and brittle fracture of NaCl powders. Large stress is mainly concentrated within the NaCl powers and the contact force network is formed. The Al powder near the NaCl powder or the mold has larger stress distribution on its contact surface. Therefore, the densification process of cold compaction of laminar Al and NaCl composite powders is successfully analyzed by the CZM-based multi particle FEM.

Keywords: cold compaction, cohesive zone, multi-particle FEM, numerical modeling, powder forming

Procedia PDF Downloads 152

Authors: Chako G. Chako

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This study reports on an ongoing research that explores pre-school mathematics. Participants in the study includes three pre-school teachers and their pre-school learners from one school in Gaborone. The school was purposefully selected based on its performance in Botswana’s 2019 national examinations. Specifically, the study is interested on teachers’ explanations of mathematics concepts embedded in pre-school mathematics tasks. The interest on explanations was informed by the view that suggests that, the mathematics learners get to learn, resides in teachers’ explanations. Recently, Botswana’s basic education has integrated pre-school education into the mainstream public primary school education. This move is part of the government’s drive to elevate Botswana to a knowledge-based-economy. It is believed that provision of pre-school education to all Batswana children will contribute immensely towards a knowledge-based-economy. Since pre-school is now a new phenomenon in our education, there is limited research at this level of education in Botswana. In particular, there is limited knowledge about what and how the teaching is conducted in Pre-Schools in Botswana. Hence, the study seeks to gain insight into what constitutes mathematics in tasks that learners are given, and how concepts are made accessible to Pre-school learners. The research question of interest for this study is stated as: What is the nature Pre-school teachers’ explanations of mathematics concepts embedded in tasks given to learners. Casting some light into what and how pre-school mathematics tasks are enacted is critical for policy and Pre-school teacher professional development. The sociocultural perspective framed the research. Adler and Rhonda’s (2014) notion of exemplification and explanatory communication are used to analyze tasks given to learners and teachers’ explanations respectively.

Keywords: classroom, explanation, mathematics, pre-school, tasks

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Authors: Sirwan Kamal, Hsein Kew, Hamid Jahromi

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This paper reports results of a study conducted to investigate strength, sorptivity, and permeability under pressure of concrete specimens, cured using a water-based curing compound. The specimens are treated with waterproofing admixtures or surface treatments to enhance performance while exposed to water. Four types of concrete specimens were prepared in the laboratory, Portland cement (CEM I), Portland-fly ash (CEM II/A-V), Blast-furnace cement (CEM III) and Portland-silica fume (CEM II/A-D). Concrete cubes were de-molded three hours after casting, and sprayed with a curing compound. Admixtures were added to the mix during batching, whereas surface treatments were applied on concrete after 28 days. Compressive strength test was carried out to assess the efficiency of curing compound to develop required strength. In addition, sorptivity and permeability tests were conducted to evaluate the performance of treated specimens with respect to water ingress. Results show that strength development in specimens cured with curing compound achieved up to 96% and 90% at 7 and 28 days respectively, compared to cubes cured in water. Moreover, specimens treated with waterproofing admixtures or surface treatments materials characterized by hydrophobic impregnation considerably reduced water penetration compared to untreated control cubes. On the other hand, cubes treated with admixtures or surface treatments materials characterized by crystalline effect were ineffective in reducing water penetration.

Keywords: admixtures, concrete, curing compound, surface treatments

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Authors: R. Hassan, J. Duncombe, E. Darke, A. Dias, K. Anderson, R. G. Middleton

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NHS England has set itself the task of delivering a “Net Zero” National Health service by 2040. It is incumbent upon all health care practioners to work towards this goal. Orthopaedic surgeons are no exception. Distal radial fractures are the most common fractures sustained by the adult population. However, studies are shortcoming on individual patient experience. The aim of this study was to assess the patient’s satisfaction and outcomes with woodcast used in the conservative management of distal radius fractures. For all patients managed with woodcast in our unit, we undertook a structured questionnaire that included the Patient Rated Wrist Evaluation (PRWE) score, The EQ-5D-5L score and the pain numerical score at the time of injury and six weeks after. 30 patients were initially managed with woodcast. 80% of patients tolerated woodcast for the full duration of their treatment. Of these, 20% didn’t tolerate woodcast and had their casts removed within 48 hours. Of the remaining, 79.1% were satisfied about woodcast comfort, 66% were very satisfied about woodcast weight, 70% were satisfied with temperature and sweatiness, 62.5% were very satisfied about the smell/odour, and 75% were satisfied about the level of support woodcast provided. During their treatment, 83.3% of patients rated their pain as five or less. For those who completed their treatment in woodcast, none required any further intervention or utilised the open appointment because of ongoing wrist problems. In conclusion, when woodcast is tolerated, patients’ satisfaction and outcome levels were good. However, we acknowledged 20% of patients in our series were not able to tolerate woodacst, Therefore, we suggest a comparison between the widely used synthetic plaster of Paris casting and woodcast to come in order.

Keywords: distal radius fractures, ecological cast, sustainability, woodcast

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Authors: A. M. Halahla, M. H. Baluch, M. K. Rahman, A. H. Al-Gadhib, M. N. Akhtar

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In the present study, 3D simulation of a typical exterior (RC) beam–column joint (BCJ) strengthened with carbon fiber-reinforced plastic (CFRP) sheet are carried out. Numerical investigations are performed using a nonlinear finite element ( FE) analysis by incorporating damage plasticity model (CDP), for material behaviour the concrete response in compression, tension softening were used, linear plastic with isotropic hardening for reinforcing steel, and linear elastic lamina material model for CFRP sheets using the commercial FE software ABAQUS. The numerical models developed in the present study are validated with the results obtained from the experiment under monotonic loading using the hydraulic Jack in displacement control mode. The experimental program includes casting of deficient BCJ loaded to failure load for both un-strengthened and strengthened BCJ. The failure mode, and deformation response of CFRP strengthened and un-strengthened joints and propagation of damage in the components of BCJ are discussed. Finite element simulations are compared with the experimental result and are noted to yield reasonable comparisons. The damage plasticity model was able to capture with good accuracy of the ultimate load and the mode of failure in the beam column joint.

Keywords: reinforced concrete, exterior beam-column joints, concrete damage plasticity model, computational simulation, 3-D finite element model

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Authors: Mustafa Abu Ghalia, Mohammed Seddik

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The design and development of a new class of biomaterial has gained particular interest in producing polymer scaffold for biomedical applications. Improving mechanical properties, biological and controlling pores scaffold are important factors to provide appropriate biomaterial for implement in soft tissue repair and regeneration. In this study, poly-ε-caprolactone (PCL) /polyethylene glycol (PEG) copolymer (80/20) incorporated with CNF scaffolds were made employing solvent casting and particulate leaching methods. Four mass percentages of CNF (1, 2.5, 5, and 10 wt.%) were integrated into the copolymer through a silane coupling agent. Mechanical properties were determined using Tensile Tester data acquisition to investigate the effect of porosity, pore size, and CNF contents. Tensile strength obtained for PCL/PEG- 5 wt.% CNF was 16 MPa, which drastically decreased after creating a porous structure to 7.1 MPa. The optimum parameters of the results were found to be 5 wt.% for CNF, 240 μm for pore size, and 83% for porosity. Scanning electron microscopy (SEM) micrograph reveals that consistent pore size and regular pore shape were accomplished after the addition of CNF-5 wt. % into PCL/PEG. The results of mass loss of PCL/PEG reinforced-CNF 1% have clearly enhanced to double values compared with PCL/PEG copolymer and three times with PCL/PEG scaffold-CNF 1%. In addition, all PCL/PEG reinforced and scaffold- CNF were partially disintegrated under composting conditions confirming their biodegradable behavior. This also provides a possible solution for the end life of these biomaterials.

Keywords: PCL/PEG, cellulose nanofibers, tissue engineering, biodegradation, compost polymers

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Authors: Benzerara Mohammed, Redjel Bachir, Kebaili Bachir

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The cracking of the concrete is a more crucial problem with the development of the complex structures related to technological progress. The projections in the knowledge of the breaking process make it possible today for better prevention of the risk of the fracture. The breaking strength brutal of a quasi-fragile material like the concrete called Toughness, is measured by a breaking value of the factor of intensity of the constraints K1C for which the crack is propagated, it is an intrinsic property of material. Many studies reported in the literature treating of the concrete were carried out on specimens which are in fact inadequate compared to the intrinsic characteristic to identify. We started from this established fact, in order to compare the evolution of the parameter of toughness K1C measured by calling upon ordinary concrete specimens of three prismatics geometries different (10*10*84) cm³ and (5*20*120) cm³ &(12*20*120) cm³ containing from the side notches various depths simulating of the cracks was set up. The notches are carried out using triangular pyramidal plates into manufactured out of sheet coated placed at the centre of the specimens at the time of the casting, then withdrawn to leave the trace of a crack. The tests are carried out in 3 points bending test in mode 1 of fracture, by using the techniques of mechanical fracture. The evolution of the parameter of toughness K1C measured with the three geometries specimens gives almost the same results. They are acceptable and return in the beach of the results determined by various researchers (toughness of the ordinary concrete turns to the turn of the 1 MPa √m). These results inform us about the presence of an economy on the level of the geometrie specimen (5*20*120) cm³, therefore to use plates specimens later if one wants to master the toughness of this material complexes, astonishing but always essential that is the concrete.

Keywords: elementary representative volume, concrete, fissure, toughness

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Authors: J. Subbalakshmi, G. Dhruvasamhith, S. M. Hussain

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Polyaniline (PANI) is one of the most extensively studied material among the conducting polymers due to its simple synthesis by chemical and electrochemical routes. PANIs have advantages of chemical stability and high conductivity making their commercial applications quite attractive. However, to our knowledge, very little work has been reported on the tensile strength properties of templated PANIs processed with polyvinyl alcohol and also, detailed study has not been carried out. We have investigated the effect of small molecule and polymers as templates on PANI. Stable aqueous colloidal suspensions of trisodium citrate (TSC), poly(ethylenedioxythiophene)-polystyrene sulfonate (PEDOT-PSS), and polyethylene glycol (PEG) templated PANIs were prepared through chemical synthesis, processed with polyvinyl alcohol (PVA) and were fabricated into films by solution casting. Absorption and infra-red spectra were studied to gain insight into the possible molecular interactions. Surface morphology was studied through scanning electron microscope and optical microscope. Interestingly, tensile testing studies revealed least strain for pure PVA when compared to the blends of templated PANI. Furthermore, among the blends, TSC templated PANI possessed maximum elasticity. The ultimate tensile strength for PVA processed, PEG-templated PANI was found to be five times more than other blends considered in this study. We establish structure–property correlation with morphology, spectral characterization and tensile testing studies.

Keywords: surface morphology, processed films, polyvinyl alcohol, templated polyanilines, tensile testing

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Authors: B. Oji, O. Olaniran

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The prospect of improving the corrosion property of Al 6063 alloy based hybrid composites reinforced with cassava peel ash (CPA) and silicon carbide (SiC) is the target of this research. It seeks to determine the viability of using locally sourced material (CPA) as a complimentary reinforcement for SiC to produce low cost high performance aluminum matrix composite. The CPA was mixed with the SiC in the ratios 0:1, 1:3, 1:1, 3:1 and 1:0 for 8 wt % reinforcement in the produced composites by double stir-casting method. The microstructures of the composites were studied before and after corrosion using the scanning electron microscopy which reveals the matrix (dark region) and eutectic phase (lamellar region). The corrosion rate was studied in accordance with ASTM G59-97 (2014) using an AutoLab potentiostat (Versa STAT 400) with versaSTUDIO electrochemical software which analyses the results obtained. The result showed that Al 6063 alloy exhibited good corrosion resistance in 0.3M H₂SO₄ and 3.5 wt. % NaCl solutions with sample C containing the 25% wt CPA showing the highest resistance to corrosion with corrosion rate of 0.0046 mmpy as compared to the control sample which has a value of 13.233 mmpy. Sample B, D, E, and F also showed a corrosion rate of 3.9502, 2.6903, 2.1223, and 5.7344 mmpy which indicated a better corrosion rate than the control in the acidic environment. The corrosion rate in the saline medium shows that sample E with 75% wt CPA has the lowest corrosion rate of 0.0422 mmpy as compared to the control sample with 0.0873 mmpy corrosion rate.

Keywords: Al-Mg-Si alloy, AutoLab potentiostat, Cassava Peel Ash, CPA, hybrid composite, stir-cast method

Procedia PDF Downloads 127

Authors: Muhammad Khubaib

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The Holy Quran purport is to establish a democratic system in which Allah has the right to special authority and He who has the supreme power or sovereignty. The supreme leader, Allah ceded the right to govern to his prophet and whoever would ever rule he would have to govern as a deputy of Prophet of Allah and he will not have the right to deviate from the basic rules of law and constitution. Centuries before the birth of prevailing democracy, Muslim scholars and researchers continuously keep using the term of “Jamhür” (majority) in their books. Islam gives the basic importance to the public opinion to establish a government and make the public confidence necessary for the government. The most effective way to gain the trust of the people in the present to build national institutions is through the vote. Vote testifies in favor of the candidate and majority tells us who is more honest and talented. Each voter stands at the position of trustworthy. To vote a cruel person would be tantamount to treason and even not to vote would be considered as a national offence. After transparent process, the selected member of government would be seemed a fine example of the saying of Muhammad (S.A.W) in which he said; the majority of my people will never be agreed at misleading. In short in this article, there would be discussed democracy in the Islamic perception, while elaborating the western democracy so that it can be cleared that in which way the Holy Quran supported the democracy and what gestures Muhammad (S.A.W) made to spread the democracy and on the basis of those gestures, and how come those gestures are being followed to choose the sacred caliphate. It's hoped that this research would be helpful to refine the democratic system and support to meet the challenges Muslim world are facing.

Keywords: democracy, modern democratic system, respect of majority opinion, vote casting

Procedia PDF Downloads 195

Authors: Jiji Jose, R. Narayanacharyulu, Molly Mathew, Jisha Prems

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Introduction: Lercanidipine hydrochloride (LD), an effective calcium channel blocker, widely used for the treatment of chronic stable angina and hypertension seems to be potential transdermal therapeutic system candidate, mainly due to its low oral bio availability, short half life and high first-pass metabolism. Objective: To develop transdermal therapeutic systems for LD and to evaluate its in vivo performance in rabbits. Methodology: Transdermal patches of LD were formulated using the polymer blend of eudragit RL100 (ERL) and polyvinyl pyrolidone (PVP) by casting method Propylene glycol (PG) and tween 80 were used as plasticizer and permeation enhancer respectively. The pharmaco kinetic parameters of LD after the administration of transdermal patches was compared with that of oral administration. The study was carried out in a two way crossover design in male New Zealand albino rabbits. Results: The formulation with ERL: PVP ratio 1:4 with 15% w/w PG as plasticizer and 4% w/w tween 80 as permeation enhancer showed the best drug release results. The pharmacokinetic parameters such as Cmax, tmax, mean residence time (MRT) and area under the curve (AUC 0-∞) were significantly different following transdermal administration compared to oral administration. The terminal half life of transdermally administered LD was found to similar that of oral administration. A sustained drug release over a period of 24 hrs was observed after transdermal administration. Conclusion: The fabricated transdermal delivery system have the potential to provide controlled and extended drug release, better bio availability and thus, this may improve the patient compliance.

Keywords: transdermal therapeutic system, lercanidipine hydrochloride, eudragit, skinpermeation

Procedia PDF Downloads 615