Search results for: diluted magnetic semiconductor materials (DMSMs)

Authors: Nader H. Ghareeb, Mohamed S. Gaith, Sayed M. Soleimani

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In modern engineering, weight optimization has a priority during the design of structures. However, optimizing the weight can result in lower stiffness and less internal damping, causing the structure to become excessively prone to vibration. To overcome this problem, active or smart materials are implemented. The coupled electromechanical properties of smart materials, used in the form of piezoelectric ceramics in this work, make these materials well-suited for being implemented as distributed sensors and actuators to control the structural response. The smart structure proposed in this paper is composed of a cantilevered steel beam, an adhesive or bonding layer, and a piezoelectric actuator. The static deflection of the structure is derived as function of the piezoelectric voltage, and the outcome is compared to theoretical and experimental results from literature. The relation between the voltage and the piezoelectric moment at both ends of the actuator is also investigated and a reduced finite element model of the smart structure is created and verified. Finally, a linear controller is implemented and its ability to attenuate the vibration due to the first natural frequency is demonstrated.

Keywords: active linear control, lyapunov stability theorem, piezoelectricity, smart structure, static deflection

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Authors: Mohamed Amine Ben Henni, Taher Hassaine Daouadji, Boussad Abbes, Yu Ming Li, Fazilay Abbes

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The reinforcement and repair of concrete structures by bonding composite materials have become relatively common operations. Different types of composite materials can be used: carbon fiber reinforced polymer (CFRP), glass fiber reinforced polymer (GFRP) as well as functionally graded material (FGM). The development of analytical and numerical models describing the mechanical behavior of structures in civil engineering reinforced by composite materials is necessary. These models will enable engineers to select, design, and size adequate reinforcements for the various types of damaged structures. This study focuses on the free vibration behavior of orthotropic laminated composite plates using a refined shear deformation theory. In these models, the distribution of transverse shear stresses is considered as parabolic satisfying the zero-shear stress condition on the top and bottom surfaces of the plates without using shear correction factors. In this analysis, the equation of motion for simply supported thick laminated rectangular plates is obtained by using the Hamilton’s principle. The accuracy of the developed model is demonstrated by comparing our results with solutions derived from other higher order models and with data found in the literature. Besides, a finite-element analysis is used to calculate the natural frequencies of laminated composite plates and is compared with those obtained by the analytical approach.

Keywords: composites materials, laminated composite plate, finite-element analysis, free vibration

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Authors: Marie Lesly Fontin, Audalbert Bien-Aimé, Didier Marlier, Yves Beckers

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Fecal digestibility of mature plantain leaves was determined in castrated Creolegoatsin order to better assess them. Five diets made from plantain leaves were used in an in vivo digestibility study on 20 castrated Creole goats over three periods using a completely random design in order to assess their apparent fecal digestibility (Dg). These diets consisted of sun-dried leaves (DL), sun-dried urea treated leaves (DUTL, 5kg of urea per 100kg of raw product ensilaged during 90 days with 60 kg of water), sun-dried leaves + hoopvine (Trichostigma octandrum, L)(DLH, DL: 61.4% + Hoopvine: 38.6%), sun-dried leaves + urea (DLU, DL: 98.2%+ U: 1.8%), and fresh leaves. (FL).0.5% of salt diluted with water was added to diets before distribution to the goats. A mineral lick block was available for each goat in its digestibility cage. During each period, diets were distributed to meet the maintenance needs of the goats for 21 days, including 14 days of adaptation and 7 days of measurement. Offered and refused diets and feces were weighed every day, and samples were taken for laboratory analysis. Results showed that the urea treatment increasedCP (Crude Protein) content of DL by 44% (from 10.4% for DL to 15.0% for DUTL) and decreased their NDF (Neutral Detergent Fiber) content (55.5% to 52.4%). Large amounts of refused feed (around 40%) were observed in goats fed with FL, DLU, and DL diets, for which no significant difference was observed for DM (Dry Matter) intakes (40.3; 36.6 and 35.1g/kg0.75 respectively) (p>0.05). DM intakes of DUTL (59.9 g/kg0.75) were significantly (p<0.05) greater than DLH (50.2 g/kg0.75). DM Dg of DL was very low (29.2%). However, supplementation with hoopvine and urea treatment resulted in a significant increase of DM Dg (40.3% and 42.1%, respectively), but the addition of urea (DLU) had no effect on it. FL showed a DM Dg similar to DHL and DUTL diets (39.0%). OM (Organic Matter)Dg was higher for the DUTL diet (45.1%), followed by DLH (40.9%), then by DLU and FL (32.9% and 40.7% respectively) and finally by DL (29.8%). CP Dg was higher for the FL diet (65.7%) and lower for the DL diet (39.9%). NDF Dg was also increased with urea treatment (54.8% for DUTL) and with the addition of hoopvine (41.4%) compared to the DL diet (31.0% for DLH). In conclusion, urea treatment and complementation with hoopvine of plantain leaves are the best treatments among those tested for increasing the nutritive value of this foragein the castrated Creole goats.

Keywords: apparent fecal digestibility, nitrogen supplements, plantain leaves, urea treatment

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Authors: Young-Cheol Choi, Sung-Won Yoo, Bong Chun Lee, Byoungsun Park, Sang-Hwa Jung

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Cracks in concrete commonly provide the passages of ingresses of aggressive and harmful ions into concrete inside and thus reduce the durability of concrete members. In order to solve this problem, self-healing concrete based on mineral admixture has become a major issue. Self-healing materials are those which have the ability of autonomously repairing some damages or small cracks in concrete structures. Concrete has an inherent healing potential, called natural healing, which can take place in ordinary concrete elements but its power is limited and is not predictable. The main mechanism of self-healing in cracked concrete is the continued hydration of unreacted binder and the crystallization of calcium carbonate. Some mineral admixtures have been found to promote the self-healing of cementitious materials. The aim of this study is to investigate the effect of mineral admixture on the self-healing performances of high strength concrete. The potential capability of self-healing of cementitious materials was evaluated using isothermal conduction calorimeter. The self-healing efficiencies were studied by means of water flow tests on cracked concrete specimens. The results show a different healing behaviour depending on presence of the crystalline admixture.

Keywords: mineral admixture, self-healing, water flow test, crystallization

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Authors: Soniya Chaudhary, Sanjeev Sahu

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Propagation of Rayleigh-type waves in a rotating piezoelectric plate is investigated. The materials are assumed to be transversely isotropic crystals. The frequency equation have been derived for electrically open and short cases. Effect of rotation and piezoelectricity have been shown. It is also found that piezoelectric material properties have an important effect on Rayleigh wave propagation. The result is relevant to the analysis and design of various acoustic surface wave devices constructed from piezoelectric materials also in SAW devices.

Keywords: rotation, frequency equation, piezoelectricity, rayleigh-type wave

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Authors: Carlos Fontanillas

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Brazil is going through a real revolution in the logistics area. It is increasingly common to find articles and news in this context, as companies begin to become aware that a good management of the areas that make up the logistics can bring excellent results in reducing costs and increasing productivity. With this, companies are investing more emphasis on reduced spending on storage and transport of their products to ensure competitiveness. The scope of this work is the analysis of the logistics of a restaurant and materials will be presented the best way to serve the customer, avoiding the interruption of production due to lack of materials; for it will be analyzed the supply chain in terms of acquisition costs, maintenance and service demand.

Keywords: ABC curve, logistic, productivity, supply chain

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Authors: Mohamed Arbi Khlifi, Badr M. Alshammari

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This paper discusses the general methods to saturation in the steady-state, two axis (d & q) frame models of synchronous machines. In particular, the important role of the magnetic coupling between the d-q axes (cross-magnetizing phenomenon), is demonstrated. For that purpose, distinct methods of saturation modeling of dumper synchronous machine with cross-saturation are identified, and detailed models synthesis in d-q axes. A number of models are given in the final developed form. The procedure and the novel models are verified by a critical application to prove the validity of the method and the equivalence between all developed models is reported. Advantages of some of the models over the existing ones and their applicability are discussed.

Keywords: cross-magnetizing, models synthesis, synchronous machine, saturated modeling, state-space vectors

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Authors: Yu Chen

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Auricular-magnet therapy is the development of auricular acupuncture. It is a powerful, convenient, and quick result-achieving therapeutic method. This therapy works by using magnetic discs to be placed on acupuncture points on the ears to treat diseases and improve health. In this study, the fundamental principles, indications, and contraindications of this therapy are discussed. Five examples, including reducing blood glucose levels, healing gangrene for diabetes patients, and treating Bell's palsy, are presented. Auricular-magnet therapy is a powerful development in acupuncture.

Keywords: auricular-magnet therapy, Bell’s palsy, diabetes mellitus, food craving, insomnia, nausea, obesity

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Authors: Frazer Kirk, Rohen Skiba, Pankaj Saxena

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The natural history of the QAV is poorly understood due to the exceeding rarity of the condition. Incidence rates vary between 0.00028-1%. Classically patients present with Aortic Regurgitation (AR) between 40-60 years of age experiencing palpitations, chest pain, or heart failure. (1, 2) Echocardiography is the mainstay of diagnosis for this condition; however, given the rarity of this condition, it can easily be overlooked, as demonstrated here. The case report that follows serves as a reminder of the condition to reduce the innate cognitive bias to overlook the diagnosis due to the availability heuristic. Intraoperative photography, echocardiographic and magnetic resonance imaging from this case for reference to demonstrate that while the diagnosis of Aortic regurgitation was recognized early, the valve morphology was underappreciated.

Keywords: quadricuspid aortic valve, cardiac surgery, echocardiography, congenital

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Authors: A. K. Paul, Vinod Kumar

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Lead free magnetoelectric (ME) nanoparticulate (1−x) BNT-BKT-BMgT−x CFO (x = 0, 0.1, 0.2, 0.3) composite films were synthesized using chemical solution deposition method. The X-ray diffraction and transmission electron microscope (TEM) reveal that CFO nanoparticles were well distributed in the matrix of BNT-BKT-BMgT. The nanocomposite films exhibit both good magnetic and ferroelectric properties at room temperature (R-T). It is concluded that the modulation in compositions of piezomagnetic/piezoelectric components plays a fundamental role in the magnetoelectric coupling in these nanoparticulate composite films. These ME composites provide a great opportunity as potential lead-free systems for ME devices.

Keywords: lead free multiferroic, nanocomposite, ferroelectric, ferromagnetic and magneto-electric properties

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Authors: P. B. Sob, T. B. Tengen, A. A. Alugongo

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Mechanical behavior of 6082T6 aluminum is investigated at different temperatures. The strain rate sensitivity is investigated at different temperatures on the grain size variants. The sensitivity of the measured grain size variants on 3-D grain is discussed. It is shown that the strain rate sensitivities are negative for the grain size variants during the deformation of nanostructured materials. It is also observed that the strain rate sensitivities vary in different ways with the equivalent radius, semi minor axis radius, semi major axis radius and major axis radius. From the obtained results, it is shown that the variation of strain rate sensitivity with temperature suggests that the strain rate sensitivity at the low and the high temperature ends of the 6082T6 aluminum range is different. The obtained results revealed transition at different temperature from negative strain rate sensitivity as temperature increased on the grain size variants.

Keywords: nanostructured materials, grain size variants, temperature, yield stress, strain rate sensitivity

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Authors: Yun Sun, Meng Xun, Jingtao Zhou, Ming Li, Qiang Kan, Zhi Jin, Xinyu Liu, Dexin Wu

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Higher speed short-wavelength vertical-cavity surface-emitting lasers (VCSELs) working at high temperature are required for future optical interconnects. In this work, the high-speed 850 nm VCSELs are designed, fabricated and characterized. The temperature dependent static and dynamic performance of devices are investigated by using current-power-voltage and small signal modulation measurements. Temperature-stable high-speed properties are obtained by employing highly strained multiple quantum wells and short cavity length of half wavelength. The temperature dependent photon lifetimes and carrier radiative times are determined from damping factor and resonance frequency obtained by fitting the intrinsic optical bandwidth with the two-pole transfer function. In addition, an analytical theoretical model including the strain effect is development based on model-solid theory. The calculation results indicate that the better high temperature performance of VCSELs can be attributed to the strong confinement of holes in the quantum wells leading to enhancement of the carrier transit time.

Keywords: vertical cavity surface emitting lasers, high speed modulation, optical interconnects, semiconductor lasers

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Authors: S. Zhuiykov, M. Karbalaei Akbari

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Ultra-low-level incorporation of trace impurities and dopants into two-dimensional (2D) semiconductors is a challenging step towards the development of functional electronic instruments based on 2D materials. Herein, the incorporation of sulphur atoms into 2D Ga2O3 surface oxide film of eutectic gallium-indium alloy (EGaIn) is achieved through plasma-enhanced metal-catalyst dissociation of H2S gas on EGaIn substrate. This process led to the growth of GaS crystalline nanodomains inside amorphous 2D Ga2O3 sublayer films. Consequently, 2D lateral heterophase was developed between the amorphous Ga2O3 and crystalline GaS nanodomains. The materials characterization revealed the alteration of photoluminescence (PL) characteristics and change of valence band maximum (VBM) of functionalized 2D films. The comprehensive studies by conductive atomic force microscopy (c-AFM) showed considerable enhancement of conductivity of 2D Ga2O3/GaS materials (300 times improvement) compared with that of 2D Ga2O3 film. This technique has a great potential for the fabrication of 2D metal oxide devices with tuneable electronic characteristics similar to nano junction memristors and transistors.

Keywords: 2D semiconductors, Ga₂O₃, GaS, plasma-induced functionalization

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Authors: Chang-Hwan Oh, Young-Jong Lee

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In April, 2015, the Ministry of Food and Drug Safety’s announcement that only 10 of the 207 products that list Cynanchum Wilfordii Radix among their ingredients were confirmed to actually contain “iyeobupiso” the counterfeit version of the “baeksuo” raised a fog to consumers who purchased health/functional foods supposedly containing the herbal medicinal material, “baeksuo” in Korean. Baeksuo is the main ingredient of the product “EstroG-100” that contain Phlomis umbrosa and Angelica gigas too (NaturalEndoTech, S.Korea). The hot water extract of the herbal medicinal materials (HMM) was approved as a product specific Health/Functional Food (HFF) having a helpful function to women reaching menopause by Korea Food & Drug Administration (Ministry of Food & Drug Safety at present). The origin of “baeksuo” is the root of Cynanchum wilfordii Hemsley in Korea (But “iyeobupiso, the root of Cynanchum auriculatum Royle ex Wight is considered as the origin of “baeksuo” in China). In Korea, about 116 HMMs are listed as the food materials in Korea Food Code among the total 187 HMMs could be used for food and medicine purpose simultaneously. But there are some chances of the HMMs (shared use for food and medicine purpose) could be misused by the part and HMMs not permitted for HFF such as the “baeksuo” case. In this study, some of HMMs (shared use for food and medicine purpose) are examined to alleviate the misuse chance of HMMs for HFFs in Korea. For the purpose of this study, the origin, shape, edible parts, efficacy and the side effects of the similar HMMs to be misused for HFF are investigated.

Keywords: herbal medicinal materials, healthy/functional foods, misuse, shared use

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Authors: Farhad Aalizadeh, Ali Moosavi

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When a blood vessel is injured, the cells of your blood bond together to form a blood clot. The blood clot helps you stop bleeding. Blood clots are made of a combination of blood cells, platelets(small sticky cells that speed up the clot-making process), and fibrin (protein that forms a thread-like mesh to trap cells). Doctors call this kind of blood clot a “thrombus.”We study the effects of different parameters on the deposition of Nanoparticles on the surface of a bump in the blood vessels by the magnetic field. The Maxwell and the flow equations are solved for this purpose. It is assumed that the blood is non-Newtonian and the number of particles has been considered enough to rely on the results statistically. Using MHD and its property it is possible to control the flow velocity, remove the fouling on the walls and return the system to its original form.

Keywords: MHD, fouling, in-vivo, blood clots, simulation

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Authors: Hsien T. Hsieh, Chao R. Chen, Li C. Chuang, Chin C. Shen

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Fenton oxidation technology is the general strategy for the treatment of organic compounds-contained wastewater. However, a considerable amount of ferric sludge was produced during the Fenton process as secondary wastes, which were needed to be further removed from the effluent and treated. In this study, heterogeneous catalysts based on ferrite oxide (Cu-Fe-Ce-O) were synthesized and characterized, and their application for Fenton-like oxidation of simulated and actual radioactive organic wastewater was investigated. The results of TOC decomposition efficiency around 54% ~ 99% were obtained when the catalyst loading, H₂O₂ loading, pH, temperature, and reaction time were controlled. In this case, no secondary wastes formed and the given catalysts were able to be separated by magnetic devices and reused again.

Keywords: fenton, oxidation, heterogeneous catalyst, wastewater

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Authors: Saurabh Chaudhury, Sanjeet Kumar Sinha

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The MOSFET has been the main building block in high performance and low power VLSI chips for the last several decades. Device scaling is fundamental to technological advancements, which allows more devices to be integrated on a single die providing greater functionality per chip. Ultimately, the goal of scaling is to build an individual transistor that is smaller, faster, cheaper, and consumes less power. Scaling continued following Moore's law initially and now we see an exponential growth in today's nano scaled chip. However, device scaling to deep nano meter regime leads to exponential increase in leakage currents and excessive heat generation. Moreover, fabrication process variability causing a limitation to further scaling. Researchers believe that with a mix of chemistry, physics, and engineering, nano electronics may provide a solution to increasing fabrication costs and may allow integrated circuits to be scaled beyond the limits of the modern transistor. Carbon nano tube (CNT) and nano wires (NW) based FETs have been analyzed and characterized in laboratory and also been demonstrated as prototypes. This work presents an extensive simulation based study and analysis of CNTFET and NW-FET devices and comparison of the results with conventional MOSFET. From this study, we can conclude that these devices have got some excellent properties and favorable characteristics which will definitely lead the future semiconductor devices in post silicon era.

Keywords: carbon nanotube, nanowire FET, low power, nanoscaled devices, VLSI

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Authors: Ankit Kargeti, Ravikant Shrivastav, Tabish Rasheed

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The electronic structure calculation for the nanoclusters of AsSiTeB/SiAsBTe quaternary semiconductor alloy belonging to the III-V Group elements was performed. Motivation for this research work was to look for accurate electronic and geometric data of small nanoclusters of AsSiTeB/SiAsBTe in the gaseous form. The two clusters, one in the linear form and the other in the bent form, were studied under the framework of Density Functional Theory (DFT) using the B3LYP functional and LANL2DZ basis set with the software packaged Gaussian 16. We have discussed the Optimized Energy, Frontier Orbital Energy Gap in terms of HOMO-LUMO, Dipole Moment, Ionization Potential, Electron Affinity, Binding Energy, Embedding Energy, Density of States (DoS) spectrum for both structures. The important findings of the predicted nanostructures are that these structures have wide band gap energy, where linear structure has band gap energy (Eg) value is 2.375 eV and bent structure (Eg) value is 2.778 eV. Therefore, these structures can be utilized as wide band gap semiconductors. These structures have high electron affinity value of 4.259 eV for the linear structure and electron affinity value of 3.387 eV for the bent structure form. It shows that electron acceptor capability is high for both forms. The widely known application of these compounds is in the light emitting diodes due to their wide band gap nature.

Keywords: density functional theory, DFT, density functional theory, nanostructures, HOMO-LUMO, density of states

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Authors: Claudio D'Alonzo

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According to recent tendencies, progress on resource efficiency is possible and it will lead to economic, environmental, and social benefits. The passage to a circular economy system, in which all the materials and energy will maintain their value for as long as possible, waste is reduced and only a few resources are used, is one of the most relevant parts of the European Union's environmental policy to develop a sustainable, competitive and low-carbon economy. A definition of circular economy can be found in Decision 1386/2013/EU of the European Parliament and of the Council on a General Union Environment Action Programme to 2020 named “Living well, within the limits of our planet”. The purpose of renewing waste management systems in the UE and making the European model one of the most effective in the world, a revised waste legislative framework entered into force in July 2018. Regarding the Italian legislation, the laws to be modified are the Legislative Decree 3 April 2006, n. 152 and the laws ruling waste management, end-of-waste, by-products and, the regulatory principles regarding circular economy. European rules on end-of-waste are not fully harmonised and so there are legal challenges. The target to be achieved is full consistency between the laws implementing waste and chemicals policies. Only in this way, materials will be safe, fit-for-purpose and designed for durability; additionally, they will have a low environmental impact.

Keywords: circular economy, end-of-waste, legislation, secondary raw materials

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Authors: Young-Doo Kwon, Seong-Hwa Jun, Dong-Jin Lee, Hyung-Seok Lee

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Ball joints support and guide certain automotive parts that move relative to the frame of the vehicle. Such ball joints are covered and protected from dust, mud, and other interfering materials by ball-joint boots made of rubber—a flexible and near-incompressible material. The boots may experience twisting and bending deformations because of the motion of the joint arm. Thus, environmental and endurance tests of ball-joint boots apply both bending and twisting deformations. In this study, environmental and endurance testing was simulated via the finite element method performed by using a commercial software package. The ranges of principal stress and principal strain values that are known to directly affect the fatigue lives of the parts were sought. By defining these ranges, the number of iterative tests and modifications of the materials and dimensions of the boot can be decreased. Therefore, instead of performing actual part tests, manufacturers can perform standard fatigue tests in trials of different materials by applying only the defined range of stress or strain values.

Keywords: boot, endurance tests, rubber, FEA

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Authors: M. A. Grigoryev, A. N. Shishkov, D. A. Sychev

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The article defines the necessity of choosing the optimal power circuits scheme of the electric drive with field regulated reluctance machine. The specific weighting factors are calculation, the linear regression dependence of specific losses in semiconductor frequency converters are presented depending on the values of the rated current. It is revealed that with increase of the carrier frequency PWM improves the output current waveform, but increases the loss, so you will need depending on the task in a certain way to choose from the carrier frequency. For task of optimization by criterion of the minimum electrical losses regression dependence of the electrical losses in the frequency converter circuit at a frequency of a PWM signal of 0 Hz. The surface optimization criterion is presented depending on the rated output torque of the motor and number of phases. In electric drives with field regulated reluctance machine with at low output power optimization criterion appears to be the worst for multiphase circuits. With increasing output power this trend hold true, but becomes insignificantly different optimal solutions for three-phase and multiphase circuits. This is explained to the linearity of the dependence of the electrical losses from the current.

Keywords: field regulated reluctance machine, the electrical losses, multiphase power circuit, the surface optimization criterion

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Authors: G. K. Awari, Vishwajeet V. Ambade, S. W. Rajurkar

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The field of additive manufacturing is growing, and discoveries are being made. 3D printing machines are also being developed to accommodate a wider range of 3D printing materials, including plastics, metals (metal AM powders), composites, filaments, and other materials. There are numerous printing materials available for industrial additive manufacturing. Such materials have their unique characteristics, advantages, and disadvantages. In order to avoid errors in additive manufacturing, key elements such as 3D printing material type, texture, cost, printing technique and procedure, and so on must be examined. It can be complex to select the best material for a particular job. Polylactic acid (PLA) is made from sugar cane or cornstarch, both of which are renewable resources. "Black plastic" is another name for it. Because it is safe to use and print, it is frequently used in primary and secondary schools. This is also how FDM screen printing is done. PLA is simple to print because of its low warping impact. It's also possible to print it on a cold surface. When opposed to ABS, it allows for sharper edges and features to be printed. This material comes in a wide range of colours. Polylactic acid (PLA) is the most common material used in fused deposition modelling (FDM). PLA can be used to print a wide range of components, including medical implants, household items, and mechanical parts. The mechanical behaviour of the printed item is affected by variations in infill patterns that are subjected to compressive tests in the current investigation to examine their behaviour under compressive stresses.

Keywords: fused deposition modelling, polylactic acid, infill density, infill pattern, compressive strength

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Authors: Joanna Styczen, Wojciech Franus

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Currently, cement production reaches 3-6 Gt per year. The production of one ton of cement is associated with the emission of 0.5 to 1 ton of carbon dioxide into the atmosphere, which means that this process is responsible for 5% of global CO2 emissions. Simply improving the cement manufacturing process is not enough. An effective solution is the use of pozzolanic materials, which can partly replace clinker and thus reduce energy consumption, and emission of pollutants and give mortars the desired characteristics, shaping their microstructure. Pozzolanic additives modify the phase composition of cement, reducing the amount of portlandite and changing the CaO/SiO2 ratio in the C-S-H phase. Zeolites are a pozzolanic additive that is not commonly used. Three types of zeolites were synthesized in work: Na-A, sodalite and ZSM-5 (these zeolites come from three different structural groups). Zeolites were obtained by hydrothermal synthesis of fly ash in an aqueous NaOH solution. Then, the pozzolanicity of the obtained materials was assessed. The pozzolanic activity of the zeolites synthesized for testing was tested by chemical methods in accordance with the ASTM C 379-65 standard. The method consisted in determining the percentage content of active ingredients (soluble silicon oxide and aluminum).in alkaline solutions, i.e. those that are potentially reactive towards calcium hydroxide. The highest amount of active silica was found in zeolite ZSM-5 - 88.15%. The amount of active Al2O3 was small - 1%. The smallest pozzolanic activity was found in the Na-A zeolite (active SiO2 - 4.4%, and active Al2O3 - 2.52). The tests carried out using the XRD, SEM, XRF and textural tests showed that the obtained zeolites are characterized by high porosity, which makes them a valuable addition to mortars.

Keywords: pozzolanic properties, hydration, zeolite, alite

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Authors: Zenaida M. De Guzman, Davison T. Baldos, Gilberto T. Diano, Jeff Darren G. Valdez, Levelyn Mitos Tolentino, Gina B. Abrera, Ma. Lucia Cobar, Cristina Gragasin

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One of the factors affecting the quality of brown rice is the free fatty acid produced from surface lipids. It is the purpose of the study to determine the effect of gamma radiation, packaging materials and age and variety of paddy on the surface free fatty acid content using two different brown rice variety, namely, RC-160 and SL-7, packed in two different packaging materials, namely, regular polyethylene bag and Super bag irradiated at 0.5 and 1.0 kGy. Brown rice was produced from 2-week old (Lot 1) and two months old paddy (Lot 2) and irradiated at the Co-60 Multipurpose Irradiation Facility, PNRI. The surface Free Fatty Acid (FFA) content was obtained following the AOCS Official Method (1982) with some modifications. The experiment was laid out using Split-Plot Randomized Control Block Design. Analysis of variance (ANOVA) showed that the effects of variety, age of paddy and interactions of both were both significant. The surface FFA of SL-7 variety was found to be significantly higher than the RC-160 variety for all radiation doses. Likewise, Lot 2 was observed to have higher surface FFA than Lot 1 regardless of packaging material and radiation dose. It was observed that the surface FFA of both varieties packed in both packaging materials increased significantly up to the 2nd or 3rd month of storage and remains the same until the 5th month. On the other hand, radiation dose did not significantly affect the surface free fatty acid content for all storage/sampling time while the packaging material significantly interacts with the type of variety and radiation dose. Gamma radiation was proven to have no significant effect on the surface free fatty acid at 0.5 and 1.0 kGy and further analyses are needed to determine the action of gamma radiation to the activity of enzyme (lipase-induced and microbial) responsible for the production of other lipolytic products and the effect of gamma radiation on the integrity of the packaging materials.

Keywords: brown rice, free fatty acid, gamma radiation, polyethylene bag

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Authors: Mohamed Elkashouty, Mohamed Elkammar, Mohamed Gomma, Menal Elminiami

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Lake Bardawil is considered as one of the major morphological features of northern Sinai. It represents the largest fish production lake for export in Egypt. Nineteen and thirty one samples were collected from lake water during winter and summer (2005). TDS, cations, anions, Cd, Cu, Fe, Mn, Zn, Ni, Co and Pb concentrations were measured within winter and summer seasons. During summer, in the eastern sector of the lake, TDS concentration is decreased due northeastern part (38000 ppm), it is attributed to dilution from seawater through Boughaz II. The TDS concentration increased generally in the central and southern parts of the lake (44000 and 42000 ppm, respectively). It is caused by they are far from dilution from seawater, disconnected water body, shallow depth (mean 2 m), and high evaporation rate. In the western sector, the TDS content ranged from low (38000 ppm) in the northeastern part to high (50000 ppm) in the western part. Generally, the TDS concentration in the western sector is higher than those in the eastern. It is attributed to low volume of water body for the former, high evaporation rate, and therefore increase in TDS content in the lake water.During winter season, in the eastern sector, the wind velocity is high which enhance the water current to inflow into the lake through Boughaz I and II. The resultant water lake is diluted by seawater and rainfall in the winter season. The TDS concentration increased due southern part of the lake (42000 ppm) and declined in the northern part (36000 ppm). The concentration of Co, Ni, Pb, Fe, Cd, Zn, Cu, Mn and Pb within winter and summery seasons, in lake water are low, which considered as background concentrations with respect to seawater. Therefore, there are no industrial, agricultural and sanitary wastewaters dump into the lake. This confirms the statement that has been written at the entrance of Lake Bardawil at El-Telool area "Lake Bardawil, one of the purest lakes in the world". It indicate that the Lake Bardawil is excellent area for fish production for export (current state) and is the second main fish source in Egypt after the Mediterranean Sea after the illness of Lake Manzala.

Keywords: lake Bardawil, water quality, major ions, toxic metals

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Authors: Namfon Samsalee, Rungsinee Sothornvit

Abstract:

Turmeric is a natural plant herb and generally extracted as essential oil and widely used in food, cosmetic, pharmaceutical products including insect repellent. However, turmeric oil is a volatile essential oil which is easy to be lost during storage or exposure to light. Therefore, biopolymers such as protein and polysaccharide can be used as wall materials to encapsulate the essential oil which will solve this drawback. Approximately 60% plasma from porcine blood contains 6-7% of protein content mainly albumin and globulin which can be a good source of animal protein at the low-cost biopolymer from by-product. Microencapsulation is a useful technique to entrap volatile compounds in the biopolymer matrix and protect them to degrade. The objective of this research was to investigate the different ratios of two biopolymers (PPP and maltodextrin; MD) as wall materials at 100:0, 75:25, 50:50, 25:75 and 0:100 at a fixed ratio of wall material: core material (turmeric oil) at 3:1 (oil in water) on the qualities of microencapsulated powder using freeze drying. It was found that the combination of PPP and MD showed higher solubility of microencapsules compared to the use of PPP alone (P < 0.05). Moreover, the different ratios of wall materials also affected on color (L*, a* and b*) of microencapsulated powder. Morphology of microencapsulated powder using a scanning electron microscope showed holes on the surface reflecting on free oil content and encapsulation efficiency of microencapsules. At least 50% of MD was needed to increase encapsulation efficiency of microencapsulates rather than using only PPP as the wall material (P < 0.05). Microencapsulated turmeric oil powder can be useful as food additives to improve food texture, as a biopolymer material for edible film and coating to maintain quality of food products.

Keywords: microencapsulation, turmeric oil, porcine plasma protein, maltodextrin

Procedia PDF Downloads 182

Authors: Constance Chivengwa, Tinashe Mandimutsira, Jephris Gere, Charles Magogo, Irene Chikanza, Jerneja Vidmar, Walter Chingwaru

Abstract:

The use of traditional methods in the management of diarrhoea has remained a common practice among the indigenous African tribes of Southern Africa. Despite the widespread use of traditional medicines in Zimbabwe, very little research validating the activities of phytomedicines against diarrhoea, as claimed by the Shona people of Zimbabwe, has been reported. This study sought to determine the efficacies of the plants that are frequently used to treat stomach complaints, namely Dicoma anomala, Cassia abbreviata, Lannea edulis and Peltophorum africanum against Escherichia coli (an indicator of faecal contamination of water, and whose strains such as EHEC (O157), ETEC and EPEC, are responsible for a number of outbreaks of diarrhoea) and Salmonella spp. Ethanol and aqueous extracts from these plants were obtained, evaporated, dried and stored. The dried extracts were reconstituted and diluted 10-fold in nutrient broth (from 100 to 0.1 microgram/mL) and tested for inhibition against the bacteria. L. edulis exhibited the best antimicrobial effect (minimum inhibition concentration = 10 microgram/mL for both extracts and microorganisms). Runners up to L. edulis were C. abbreviata (20 microgram/mL for both microorganisms) and P. africanum (20 and 30 microgram/mL respectively). Interestingly, D. anomala, which is widely considered panacea in African medicinal practices, showed low antimicrobial activity (60 and 100 microgram/mL respectively). The high antimicrobial activity of L. edulis can be explained by its content of flavonoids, tannins, alkylphenols (cardonol 7 and cardonol 13) and dihydroalkylhexenones. The antimicrobial activities of C. abbreviata can be linked to its content of anthraquinones and triterpenoids. P. africanum is known to contain benzenoids, flavanols, flavonols, terpenes, xanthone and coumarins. This study therefore demonstrated that, among the plants that are used against diarrhoea in African traditional medicine, L. edulis is a clear winner against E. coli and Salmonella spp. Activity guided extraction is encouraged to establish the complement of compounds that have antimicrobial activities.

Keywords: diarrhoea, Escherichia coli, Salmonella, phytomedicine, MIC, Zimbabwe

Procedia PDF Downloads 367

Authors: E. Cintura, M. I. Gomes

Abstract:

Nowadays, sustainable development issues have a key role in the planning of the man-made environment. Ensuring this development means limiting the impact of human activity on nature. It is essential to secure healthy places and good living conditions. For these reasons, indoor air quality and building materials play a fundamental role in sustainable architectural projects. These factors significantly affect human health: they can radically change the quality of the internal environment and energy consumption. The use of natural materials such as earth has many beneficial aspects in comfort and indoor air quality. As well as advantages in the environmental impact of the construction, they ensure a low energy consumption. Since they are already present in nature, their production and use do not require a high-energy consumption. Furthermore, they have a high thermo-hygrometric capacity, being able to absorb moisture, contributing positively to indoor conditions. Indoor air quality is closely related to relative humidity. For these reasons, it can be affirmed that the use of earth materials guarantees a sustainable development and at the same time improves the health of the building users. This paper summarizes several researches that demonstrate the importance of indoor air quality for human health and how it strictly depends on the building materials used. Eco-efficient plasters are also considered: earth and ash mortar. The bibliography consulted has the objective of supporting future experimental and laboratory analyzes. It is necessary to carry on with research by the use of simulations and testing to confirm the hygrothermal properties of eco-efficient plasters and therefore their ability to improve indoor air quality.

Keywords: hygroscopicity, hygrothermal comfort, mortar, plaster

Procedia PDF Downloads 138

Authors: Zong-Sheng Chen

Abstract:

With the advancement of technology, human activities have increased greenhouse gas emissions and fossil fuel energy production, leading to increasingly severe global warming. To mitigate global warming, energy conservation and carbon reduction have become global goals. Solar energy, a renewable energy source, not only helps achieve energy conservation and carbon reduction but also serves as an efficient energy generation method. Solar energy, derived from sunlight, is an endless and promising energy source capable of meeting high energy demands sustainably. In recent years, many countries around the world have been developing the solar energy industry, and Taiwan is no exception. Positioned in the subtropical region, Taiwan possesses geographical advantages conducive to solar energy utilization. Furthermore, Taiwan's well-developed semiconductor technology and sophisticated equipment make it highly suitable for the development of high-efficiency solar cells. This study focuses on investigating the anti-reflection properties of solar cells. Through metal-assisted chemical etching, pyramid structures are etched to allow sunlight to pass through, achieving secondary or higher-order reflections on the surface of these structures. This trapping of light within the substrate reduces reflection rates and increases conversion efficiency.

Keywords: solar cell, reflectance, pyramidal structure, potassium hydroxide

Procedia PDF Downloads 61

Authors: Reza Gheisari, Paulo J. Bartolo, Nicholas Goddard

Abstract:

Polymeric micro-cantilevers (Cs) are rapidly becoming popular for MEMS applications such as chemo- and bio-sensing as well as purely electromechanical applications such as microrelays. Polymer materials present suitable physical and chemical properties combined with low-cost mass production. Hence, micro-cantilevers made of polymers indicate much more biocompatibility and adaptability of rapid prototyping along with mechanical properties. This research studies the effects of three process and one size factors on the filling behaviour in micro cavity, and the role of each in the replication of micro parts using different polymer materials i.e. polypropylene (PP) SABIC 56M10 and acrylonitrile butadiene styrene (ABS) Magnum 8434. In particular, the following factors are considered: barrel temperature, mould temperature, injection speed and the thickness of micro features. The study revealed that the barrel temperature and the injection speed are the key factors affecting the flow length of micro features replicated in PP and ABS. For both materials, an increase of feature sizes improves the melt flow. However, the melt fill of micro features does not increase linearly with the increase of their thickness.

Keywords: flow length, micro cantilevers, micro injection moulding, microfabrication

Procedia PDF Downloads 392