Search results for: composite recycling

Authors: Subal Kar, Amitesh Kumar, A. Majumder, S. K. Ghosh, S. Saha, S. S. Sikdar, T. K. Saha

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CRLH (composite right/left-handed) based and SRR (split-ring resonator) based filters have been designed at microwave frequency which can provide better performance compared to conventional edge-coupled band-pass filter designed around the same frequency, 2.45 GHz. Both CRLH and SRR are unit cells used in metamaterial design. The primary aim of designing filters with such structures is to realize size reduction and also to realize novel filter performance. The CRLH based filter has been designed in microstrip transmission line, while the SRR based filter is designed with SRR loading in waveguide. The CRLH based filter designed at 2.45 GHz provides an insertion loss of 1.6 dB with harmonic suppression up to 10 GHz with 67 % size reduction when compared with a conventional edge-coupled band-pass filter designed around the same frequency. One dimensional (1-D) SRR matrix loaded in a waveguide shows the possibility of realizing a stop-band with sharp skirts in the pass-band while a stop-band in the pass-band of normal rectangular waveguide with tailoring of the dimensions of SRR unit cells. Such filters are expected to be very useful for communication systems at microwave frequency.

Keywords: BPF, CRLH, harmonic, metamaterial, SRR and waveguide

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Authors: Claudia Schier, Arvid Biallas, Bernd Friedrich

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The demand for Li-ion-batteries owing to their benefits, such as; fast charging time, high energy density, low weight, large temperature range, and a long service life performance is increasing compared to other battery systems. These characteristics are substantial not only for battery-operated portable devices but also in the growing field of electromobility where high-performance energy storage systems in the form of batteries are highly requested. Due to the sharp rising production, there is a tremendous interest to recycle spent Li-Ion batteries in a closed-loop manner owed to the high content of valuable metals such as cobalt, manganese, and lithium as well as regarding the increasing demand for those scarce applied metals. Currently, there are just a few industrial processes using hydrometallurgical methods to recover valuable metals from Li-ion-battery waste. In this study, the extraction of valuable metals from spent Li-ion-batteries is investigated by pretreated and subsequently leached battery wastes using different precipitation methods in a comparative manner. For the extraction of lithium, cobalt, and other valuable metals, pelletized battery wastes with an initial Li content of 2.24 wt. % and cobalt of 22 wt. % is used. Hydrochloric acid with 4 mol/L is applied with 1:50 solid to liquid (s/l) ratio to generate pregnant leach solution for subsequent precipitation steps. In order to obtain pure precipitates, two different pathways (pathway 1 and pathway 2) are investigated, which differ from each other with regard to the precipitation steps carried out. While lithium carbonate recovery is the final process step in pathway 1, pathway 2 requires a preliminary removal of lithium from the process. The aim is to evaluate both processes in terms of purity and yield of the products obtained. ICP-OES is used to determine the chemical content of leach liquor as well as of the solid residue.

Keywords: hydrochloric acid, hydrometallurgy, Li-ion-batteries, metal recovery

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Authors: A. Suresh, Sreehari Rao Patri, K. S. R. Krishnaprasad

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An ultra low power capacitor less low-dropout voltage regulator with improved transient response using gain enhanced feed forward path compensation is presented in this paper. It is based on a cascade of a voltage amplifier and a transconductor stage in the feed forward path with regular error amplifier to form a composite gain-enhanced feed forward stage. It broadens the gain bandwidth and thus improves the transient response without substantial increase in power consumption. The proposed LDO, designed for a maximum output current of 100 mA in UMC 180 nm, requires a quiescent current of 69 µA. An undershoot of 153.79mV for a load current changes from 0mA to 100mA and an overshoot of 196.24mV for current change of 100mA to 0mA. The settling time is approximately 1.1 µs for the output voltage undershoot case. The load regulation is of 2.77 µV/mA at load current of 100mA. Reference voltage is generated by using an accurate band gap reference circuit of 0.8V.The costly features of SOC such as total chip area and power consumption is drastically reduced by the use of only a total compensation capacitance of 6pF while consuming power consumption of 0.096 mW.

Keywords: capacitor-less LDO, frequency compensation, transient response, latch, self-biased differential amplifier

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Authors: Ajeevan Gautam, Gulam Anwer Khan, Pratibha Pokhrel

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Introduction: Dermatoglyphics is the science which deals with the study of dermal ridge configuration on the digits, palms and soles. It is grooved by ridges and forms variety of configurations. The aim of the study was to identify dermal ridge patterns on fingertip of hypertensive patients and in normal population and to compare patterns among them. Methods: The subjects of the study were 130 hypertensives and 130 non-hypertensives cases of Kathmandu Valley aged between 40 to 80 years. Case history was recorded after consent finger prints were taken. Different parameters as whorl, loop, arch and composite patterns were studied and analysed. Result: It revealed, increased whorl pattern in hypertensive. It showed 65.69% whorl, 29.23% loop and 5.07% arch patterns in right hand of hypertensive people. In control, it was found to be 34.46% whorl, 58.15% loop and 5.38% arch patterns respectively. Similarly in left hand 63.69% whorl, 32% loop and 4.30% arch in hypertensive group. In control group it was 60.15% as loop, 35.69% as whorl and 15% as arch. Discussion: Based on findings of the result, it was concluded that the whorl, loop and arch patterns observed as 65.69%, 29.23% and 5.07% respectively in hypertensive cases in right hand. Similarly in left hand, it was found to be 4.30% as arch, 32% as loop and 63.69% as whorl patterns, but in normotensive subjects these patterns were recorded as 36.43%, 58.15%, 5.38% in right hand and 35.69%, 60.15%, 4.15% in left hand as whorl, loop and arch respectively.

Keywords: arch, dermatoglyphics, hypertension, loop, whorl

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Authors: Wasi Khan, Suboohi Shervani, Swaleha Naseem, Mohd. Shoeb, J. A. Khan, B. R. Singh, A. H. Naqvi

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We have successfully synthesized ZnO/TiO2 nanocomposite using a two-step solochemical synthesis method. The influence of annealing temperature on microstructural, optical, anticandidal, photocatalytic activities and dielectric properties were investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) show the formation of nanocomposite and uniform surface morphology of all samples. The UV-Vis spectra indicate decrease in band gap energy with increase in annealing temperature. The anticandidal activity of ZnO/TiO2 nanocomposite was evaluated against MDR C. albicans 077. The in-vitro killing assay revealed that the ZnO/TiO2 nanocomposite efficiently inhibit the growth of the C. albicans 077. The nanocomposite also exhibited the photocatalytic activity for the degradation of methyl orange as a function of time at 465 nm wavelength. The electrical behaviour of composite has been studied over a wide range of frequencies at room temperature using complex impedance spectroscopy. The dielectric constants, dielectric loss and ac conductivity (σac) were studied as the function of frequency, which have been explained by ‘Maxwell Wagner Model’. The data reveals that the dielectric constant and loss (tanδ) exhibit the normal dielectric behavior and decreases with the increase in frequency.

Keywords: ZnO/TiO2 nanocomposites, SEM, photocatalytic activity, dielectric properties

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Authors: Krutika K. Sawant, Anil Solanki

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The present study deals with the preparation and optimization of ethyl cellulose-containing disopyramide phosphate loaded microspheres using solvent evaporation technique. A central composite design consisting of a two-level full factorial design superimposed on a star design was employed for optimizing the preparation microspheres. The drug:polymer ratio (X1) and speed of the stirrer (X2) were chosen as the independent variables. The cumulative release of the drug at a different time (2, 6, 10, 14, and 18 hr) was selected as the dependent variable. An optimum polynomial equation was generated for the prediction of the response variable at time 10 hr. Based on the results of multiple linear regression analysis and F statistics, it was concluded that sustained action can be obtained when X1 and X2 are kept at high levels. The X1X2 interaction was found to be statistically significant. The drug release pattern fitted the Higuchi model well. The data of a selected batch were subjected to an optimization study using Box-Behnken design, and an optimal formulation was fabricated. Good agreement was observed between the predicted and the observed dissolution profiles of the optimal formulation.

Keywords: disopyramide phosphate, ethyl cellulose, microspheres, controlled release, Box-Behnken design, factorial design

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Authors: Mohammed Sghir Taleb

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Introduction The date palm (Phoenix dactylifera L.) represents an essential element of the oasis ecosystem for Saharan and pre-Saharan regions of Morocco. It plays an important role, not only due to its economic importance, but also its ecological adaptation to, firstly, to ensure necessary protection for crops against underlying warm and dry sales, and secondly to contribute to the fight against desertification. This is one of the oldest cultivated plant species best adapted to difficult climatic conditions of the Saharan and pre-Saharan regions, because of its ecological requirements and economically most suitable for investing in oasis agriculture. Methodology The methodology is mainly based on a literature review of principal theses and projects for the conservation of flora and vegetation. Results The date palm has multiple uses. Indeed, it produces fruits rich in nutrients, provides a multitude of secondary products and generates needed revenue for the survival of oasis populations. In Morocco, the development and modernization of the date palm sector face, both upstream and downstream of the industry, several major constraints. In addition to climate constraints (prolonged drought), in its environment (lack of water resources), to the incessant invasion of disease Bayoud, Moroccan palm ecosystem suffers from a low level of technical and traditional practices prevail and traditional, from the choice of variety and site preparation up to harvesting and recycling of products. Conclusion The date palm plays an important role in the socioeconomic development of local and national level. However, this ecosystem however, is subject to numerous degradation factors caused by anthropogenic action and climate change. to reverse the trends, several programs have been developed by Morocco for the restoration of degraded areas and the development of the Phoenix dactylifera ecosystem to meet the needs of local populations and the development of the national economy.

Keywords: efforts, flora, ecosystem, forest, conservation, Morocco

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Authors: Nacer Hamza

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Naturally radiation exposure that present due to the cosmic ray or the naturel occurring radioactives materials(NORMs) that originated in the earth's crust and are present everywhere in the environment(1) , a significant concentration of NORMs reported in the produced water which comes out during the oil extraction process, so that the management of this produced water is a challenge for oil and gas companies which include either minimization of produced water which considered as the best way in the term of environment based in the fact that ,the lower water produced the lower cost in treating this water , recycling and reuse by reinjected produced water that fulfills some requirements to enhance oil recovery or disposal in the case that the produced water cannot be minimize or reuse. In the purpose of produced water management, the investigation of NORMs activity concentration present in it considered as the main step for more understanding of the radionuclide’s distribution. Many studies reported the present of NORMs in produced water and investigated the correlation between 〖Ra〗^226and the different metals present in produced water(2) including Cations and anions〖Na〗^+,〖Cl〗^-, 〖Fe〗^(2+), 〖Ca〗^(2+) . and lead, nickel, zinc, cadmium, and copper commonly exist as heavy metal in oil and gas field produced water(3). However, there are no real interesting to investigate the correlation between 〖Rn〗^222and the different metals exist in produced water. methods using, in first to measure the radon concentration activity in produced water samples is a RAD7 .RAD7 is a radiometer instrument based on the solid state detectors(4) which is a type of semi-conductor detector for alpha particles emitting from Rn and their progenies, in second the concentration of different metals presents in produced water measure using an atomic absorption spectrometry AAS. Then to investigate the correlation between the 〖Rn〗^222concentration activity and the metals concentration in produced water a statistical method is Pearson correlation analysis which based in the correlation coefficient obtained between the 〖Rn〗^222 and metals. Such investigation is important to more understanding how the radionuclides act in produced water based on this correlation with metals , in first due to the fact that 〖Rn〗^222decays through the sequence 〖Po〗^218, 〖Pb〗^214, 〖Bi〗^214, 〖Po〗^214, and〖Pb〗^210, those daughters are metals thus they will precipitate with metals present in produced water, secondly the short half-life of 〖Rn〗^222 (3.82 days) lead to faster precipitation of its progenies with metals in produced water.

Keywords: norms, radon concentration, produced water, heavy metals

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Authors: Moustafa A. Fadel, Omar Al Shehhi, Mohsin Al Mussabi, Abdullah Al Ameri

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Hydroponics represents an extraordinary promising technique if used efficiently in arid regions where water resources are extremely scarce where a great portion of the used water should be recycled and saved. Available research publications studying the production of seedlings for such purpose are limited. This research paper focuses on investigating the effect of using various substrate materials on the development of seedlings for ornamental plants. Bermuda grass, Petunia (Compacta Enana Rosa) and Epipremnum aureum are used widely in landscape design. Bermuda is used as a turf grass; Petunia is used as a flowering plant and Epipremnum aureum as an indoor ornamental plant in hydroponics. Three substrate materials were used to germinate and propagate the first two and the cuttings of the third one. Synthetic sponge (Polyurethane sponge), Rockwool and sterilized cotton were used as the substrate material in each case where an experimental water-circulating apparatus was designed and installed to execute the test. An experimental setup of closed hydroponic apparatus was developed to carry out the experiment equipped with water recycling circuit and an aeration mechanism pumping air in reservoir in order to increase oxygen levels in the recycled water. Water pumping was programmed in different regimes to allow better aeration for seeds and cuttings under investigation. Results showed that Bermuda grass germinated in Rockwool reached a germination rate of 70% while it did not exceed 50% when sponge and medically treated cotton were used after 15 days. On the other hand the highest germination rate of Petunia was observed when treated cotton was used where it recorded about 30% while it was 22%, and 7% after 20 days where Rockwool and sponge were utilized respectively. Cuttings propagation of Epipremnum aureum developed the highest number of shoots when treated cotton was used where it gave 10 shoots after 10 days while it gave just 7 shoots when Rockwool and sponge were used as the propagation substrate.

Keywords: hydroponics, germination, seedlings, cuttings

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Authors: Daniel Barros, Carlos Mota, Raul Fangueiro, Pedro Rosa, Gonçalo Domingos, Alfredo Passanha, Norberto Almeida

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The main aim of the work was to compare the ballistic performance of developed composites using different types of fiber woven fabrics [0,90] and different layers orientation (Angle-ply). The ballistic laminate composites were developed using E-glass, S-glass and aramid fabrics impregnated with thermosetting epoxy resin and using different layers orientation (0,0)º and (0,15)º. The idea of the study is to compare the ballistic performance of each laminate produced by studying the velocity loss of the fragment fired into the laminate surface. There are present some mechanical properties for laminates produced using the different types of fiber, where tensile, flexural and impact Charpy properties were studied. Overall, the angle-ply laminates produced using orientations of (0,15)º, despite the slight loss of mechanical properties compared to the (0,0)º orientation, presents better ballistic resistance and dissipation of energy, for lower ballistic impact velocities (under 290 m/s-1). After treatment of ballistic impact results, the S-Glass with (0,15)º laminate presents better ballistic perforce compared to the other combinations studied.

Keywords: ballistic impact, angle-ply, ballistic composite, s-glass fiber, aramid fiber, fabric fiber, energy dissipation, mechanical performance

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Authors: Yulu Zhang, Atushi Teramoto, Taka-Aki Ohkubo

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In this study, the effect of expansive additives on autogenous shrinkage and delayed expansion of ultra-high strength mortar was explored. The specimens made for the study were composed of ultra-high strength mortar, which was mixed with ettringite-lime composite type expansive additive. Two series of experiments were conducted with the specimens. The experimental results confirmed that the autogenous shrinkage of specimens was effectively decreased by increasing the proportion of the expansive additive. On the other hand, for the specimens, which had 7% expansive additive, and were cured for seven days at a constant temperature of 20°C, and then cured for a long time in either in an underwater, moist (Relative humidity: 100%) or dry air (Relative humidity: 60%) environment, excessively large expansion strain occurred. Specifically, typical turtle shell-like swelling expansion cracks were confirmed in the specimens that underwent long-term curing in an underwater and moist environment. According to the result of hydration analysis, the formation of expansive substances, calcium hydroxide and alumina, ferric oxide, tri-sulfate contribute to the occurrence of delayed expansion.

Keywords: ultra-high strength mortar, expansive additive, autogenous shrinkage, delayed expansion

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Authors: Babak Safaei, A. M. Fattahi

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In the present study we have investigated axial buckling characteristics of nanocomposite beams reinforced by single-walled carbon nanotubes (SWCNTs). Various types of beam theories including Euler-Bernoulli beam theory, Timoshenko beam theory and Reddy beam theory were used to analyze the buckling behavior of carbon nanotube-reinforced composite beams. Generalized differential quadrature (GDQ) method was utilized to discretize the governing differential equations along with four commonly used boundary conditions. The material properties of the nanocomposite beams were obtained using molecular dynamic (MD) simulation corresponding to both short-(10,10) SWCNT and long-(10,10) SWCNT composites which were embedded by amorphous polyethylene matrix. Then the results obtained directly from MD simulations were matched with those calculated by the mixture rule to extract appropriate values of carbon nanotube efficiency parameters accounting for the scale-dependent material properties. The selected numerical results were presented to indicate the influences of nanotube volume fractions and end supports on the critical axial buckling loads of nanocomposite beams relevant to long- and short-nanotube composites.

Keywords: nanocomposites, molecular dynamics simulation, axial buckling, generalized differential quadrature (GDQ)

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Authors: Seyfullah Madakbas, Emrah Cakmakci

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Polyaniline (PANI), the most studied member of the conductive polymers, has a wide range of uses from several electronic devices to various conductive high-technology applications. Boron nitride (BN) is a boron and nitrogen containing compound with superior chemical and thermal resistance and thermal conductivity. Even though several composites of PANI was prepared in literature, the preparation of h-BN/PANI composites is rare. In this work PANI was polymerized in the presence of different amounts of h-BN (1, 3 and 5% with respect to PANI) by using 0.1 M solution of NH4S2O8 in HCl as the oxidizing agent and conductive composites were prepared. Composites were structurally characterized with FTIR spectroscopy and X-Ray Diffraction (XRD). Thermal properties of conductive composites were determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Dielectric measurements were performed in the frequency range of 106–108 Hz at room temperature. The corresponding bands for the benzenoid and quinoid rings at around 1593 and 1496 cm-1 in the FTIR spectra of the composites proved the formation of polyaniline. Together with the FTIR spectra, XRD analysis also revealed the existence of the interactions between PANI and h-BN. Glass transition temperatures (Tg) of the composites increased with the increasing amount of PANI (from 87 to 101). TGA revealed that the char yield of the composites increased as the amount of h-BN was increased in the composites. Finally the dielectric permittivity of 3 wt.%h-BN-containing composite was measured and found as approximately 17. This work was supported by Marmara University, Commission of Scientific Research Project.

Keywords: dielectric permittivity, h-BN, PANI, thermal analysis

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Authors: Samir Hassan AL-Nesrawy, Mohammed Al-Maamori, A. S. Hassani

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Rebound resilience for various elastomeric composites has been measured by Tripsometer devise, in order to investigate the effect of mix of C.B & Reclaim loading on elastomeric materials to absorb or damping vibration or shocks by fenders uses in the Iraqi berths. After having been certain about attaining the physical and mechanical properties of the new samples which are similar to the levels of their standard ones, damping properties for the new samples have been measured and compared with those of the standard fenders. The new samples included four rubber blends from (SBR/NR/BR-cis) and four loading levels of mix carbon black (type N-375) and reclaim to become sixteen compound contain SBR(100,60,60,60), NR(0,10,20,30), BRcis(30,20,10,0) and loading level for C.B, Reclaim (10,20,30,40). Damping measurements have been carried out by the method Free Vibration Resilience Pendulum method (by using Wallace R2-Dunlop Tripsometer) and from this Resilience Pendulum method, both the resilience percentage value (R%) and time decay (t0) have been measured at 50oC. We found that the results of this method proved that the increment of C.B, Reclaim level in these robber composite lead to decreasing the resiliency (R%) and damping time.

Keywords: damping materials, carbon black mixture effect, mechanical properties, rubber blends SBR/NR/BRcis

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Authors: Adeyemi Kamil Hamzah

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The contiguity of nations in international system suggests that world is a composite of socio-economic unit with people exploring and exploiting the potentials in the world via migrations. Thus, cross border migration has made positive contributions to social and economic development of individuals and nations by increasing the household incomes of the host countries. However, the cross border migrations in West Africa are becoming part of a dynamic and unstable world migration system. This is due to the nature and consequences of trans-border crimes in West Africa, with both short and long term effects on the socio-economic viability of developing countries like West African States. The paper identified that migration influenced cross-border crimes as well as the high spate of insurgencies in the sub-region. Furthermore, the consequential effect of a global village has imbalanced population flows, making some countries host and parasites to others. Also, stern and deft cross-border rules and regulations, as well as territorial security and protections, ameliorate cross border crimes and migration in West African sub-regions. Therefore, the study concluded that cross border migration is the linchpin of all kinds of criminal activities which affect the security of states in the sub-region.

Keywords: cross-border migration, border crimes, security, West Africa, development, globalisation

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Authors: Pascal U. Onu, Doris A. Ogbang, Emmanuel Okechukwu.

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Background: Plastics in their various forms have become ubiquitous in a very short space of time. This ubiquitous nature has plagued and daunted nations globally, overwhelming their ability to manage the environmental impact, especially its linkages to climate change. This has mobilized nations globally and triggered debates on the best approaches to ensure sustainability in terms of its production and utilization, as total elimination seems unrealistic. Objective: This study undertook to understand the pattern of plastic waste management, and its pollution awareness levels by the residents of the study area. Methods: Data were obtained through questionnaires designed specifically for plastic waste and qualitatively via journals and articles. Simple descriptive survey techniques with a survey population size of 300 respondents using kobo collect were employed. Results: Analysis based on disaggregated data indicated a proportionate distribution among male and female respondents (53% male and 47% female, respectively). Overall awareness levels on plastic waste's contribution to climate change, compared to its environmental impact, are reflective of a dire need for increased efforts in strengthening awareness creation, especially across gender populations and religious backgrounds. Drainage blockage topped the ranks among common problems caused by plastic waste within the area. Various plastic waste disposal methods were ranked, while pro-environmental measures for reducing the waste menace showed more willingness from males at 52%. Conclusion: These outcomes are instructive and suggest the need for renewed and increased awareness/education on the nexus of plastic pollution to climate change and also appropriate synergies/collaboration between government, private sector, and local communities, especially in the area of recycling to improve sustainability in plastic waste management.

Keywords: plastic waste, KAP, climate change, Nigeria

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Authors: Dita Mayasari, Zahrina Mardina, Riki Siswanto, Agresta Ifada, Ova Oktavina, Prihartini Widiyanti

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Heart failure is a serious major health problem with high number of mortality per year. Bypass is one of the solutions that has often been taken. Natural vascular graft (xenograft) as the substitute in bypass is inconvenient due to ethic problems and the risk of infection transmission caused by the usage of another species transgenic vascular. Nowadays, synthetic materials have been fabricated from polymers. The aim of this research is to make a synthetic vascular graft with great physical strength, high biocompatibility, and good affordability. The method of this research was mixing PLGA and collagen by magnetic stirrer. This composite were shaped by spinneret with water as coagulant. Then it was coated by chitosan with 3 variations of weight (1 gram, 2 grams, and 3 grams) to increase hemo and cytocompatibility, proliferation, and cell attachment in order for the vascular graft candidates to be more biocompatible. Mechanical strength for each variation was 5,306 MPa (chitosan 1 gram), 3,433 MPa (chitosan 2 grams) and 3,745 MPa (chitosan 3 grams). All the tensile values were higher than human vascular tensile strength. Toxicity test showed that the living cells in all variations were more than 60% in number, thus the vascular graft is not toxic.

Keywords: chitosan, collagen, PLGA, spinneret

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Authors: Ehsan Sadie

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The use of steel braces in concrete structures has been considered by researchers in recent decades due to its easy implementation, economics and the ability to create skylights in braced openings compared to shear wall openings as well as strengthening weak concrete structures to earthquakes. The purpose of this article is to improve and strengthen concrete structures with steel bracing. In addition, cases such as different numbers of steel braces in different openings of concrete structures and interaction between concrete frames and metal braces have been studied. In this paper, by performing static nonlinear analysis and examining ductility, the relative displacement of floors, examining the performance of samples, and determining the coefficient of behavior of composite frames (concrete frames with metal bracing), the behavior of reinforced concrete frames is compared with frame without bracing. The results of analyzes and studies show that the addition of metal bracing increases the strength and stiffness of the frame and reduces the ductility and lateral displacement of the structure. In general, the behavior of the structure against earthquakes will be improved.

Keywords: behavior coefficient, bracing, concrete structure, convergent bracing, earthquake, linear static analysis, nonlinear analysis, pushover curve

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Authors: Jau-Shya Lee, Rossita Shapawi, Vin Cent Pua

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Tilapia is a popular cultured fresh-water fish in Malaysia. The highly perishable nature of the fish and increasing demand for high-quality ready-to-cook fish has intensified the search for better fish preservation method. Chitosan edible coating has been evident to extend the shelf life of fish fillet. This work was attempted to explore the potential of ascorbic acid in enhancing the shelf life extension ability of chitosan coated Tilapia fillet under refrigeration condition (4 ± 1oC). A 3 2 Factorial Design which comprising of three concentrations of chitosan (1, 1.5 and 2%) and two concentrations of ascorbic acids (2.5 and 5%) was used. The fish fillets were analyzed for total viable count, thiobarbituric acid (TBA) value, pH, aw and colour changes at 3-day interval over 15-day storage. The shelf life of chitosan coated (1.5% and 2%) fillet was increased to 15 days as compared to uncoated fish fillet which can only last for nine days. The inhibition of microbial growth of fish fillet was enhanced with the addition of 5% of ascorbic acids in 2% of chitosan. The TBA value, pH and aw for chitosan coated samples were found lower than that of uncoated sample (p<0.05). The colour stability of the fish fillet was also improved by the composite coating. Overall, 2% of chitosan and 5% of ascorbic acid formed the most effective coating to enhance the quality and to lengthen the shelf life of refrigerated Tilapia fillet.

Keywords: ascorbic acid, chitosan, edible coating, fish fillet

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Authors: Farzaneh Tahmoorian, Bijan Samali, John Yeaman

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Road networks are expanding all over the world during the past few decades to meet the increasing freight volumes created by the population growth and industrial development. At the same time, the rate of generation of solid wastes in the society is increasing with the population growth, technological development, and changes in the lifestyle of people. Thus, the management of solid wastes has become an acute problem. Accordingly, there is a need for greater efficiency in the construction and maintenance of road networks, in reducing the overall cost, especially the utilization of natural materials such as aggregates. An efficient means to reduce construction and maintenance costs of road networks is to replace natural (virgin) materials by secondary, recycled materials. Recycling will also help to reduce pressure on landfills and demand for extraction of natural virgin materials thus ensuring sustainability. Application of solid wastes in asphalt layer reduces not only environmental issues associated with waste disposal but also the demand for virgin materials which will subsequently result in sustainability. Therefore, this research aims to investigate the feasibility of the application of some of the waste materials such as glass, construction and demolition wastes, etc. as alternative materials in pavement construction, particularly flexible pavements. To this end, various combination of different waste materials in certain percentages is considered in designing the asphalt mixture. One of the goals of this research is to determine the optimum percentage of all these materials in the mixture. This is done through a series of tests to evaluate the volumetric properties and resilient modulus of the mixture. The information and data collected from these tests are used to select the adequate samples for further assessment through advanced tests such as triaxial dynamic test and fatigue test, in order to investigate the asphalt mixture resistance to permanent deformation and also cracking. This paper presents the results of these investigations on the application of waste materials in asphalt mixture for production of a sustainable asphalt mix.

Keywords: asphalt, glass, pavement, recycled aggregate, sustainability

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Authors: Juniarti, Yusniwati, Anwar. A, Armansyah, Febriamansyah, R.

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Simawang area is one of the critical areas (sub-optimal) that experienced drought from climate changes. Potential dry land belonging to sub-optimal in Simawang, West Sumatera, Indonesia not been fully utilized for agricultural cultivation. Simawang village, West Sumatera, Indonesia is formerly known as the rice barn, due to the climate change area is experiencing a drought, so the rice fields that were once productive now a grazing paddock because of lack of water. This study aims to calculate the soil carbon stock in Simawang village, West Sumatera Indonesia. The study was conducted in Simawang village, Tanah Datar regency, West Sumatera from October 2014 until December 2017. The study was conducted on sub-optimal land to be planted with Cymbopogon nardus L. (Sereh wangi in Indonesian language). Composite soil sampling conducted at a depth of 0-20 cm, 20 – 40 cm. Based on the depth of soil carbon stocks gained higher ground 6473 t ha-1 at a depth of 0-20 cm at a depth of 20-40 cm. Efforts to increase soil carbon is expected to be cultivated through Cymbopogon nardus L. planting has been done.

Keywords: climate changes, sereh wangi (Cymbopogon nardus L.), soil carbon stock, sub optimal land

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Authors: Mehmet Fahri Sarac, Gokcen Akgun

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Ti–6Al–4V alloys are widely used in biomedical industries because of its attractive mechanical and physicochemical properties. However, they have poor wear resistance. High velocity oxygen fuel (HVOF) coatings were investigated as a way to improve the wear resistance of this alloy. In this paper, different mass ratio of Al₂O₃-TiO₂ powders (60/40, 87/13 and 97/3) was employed to enhance the tribological properties of Ti–6Al–4V. The tribological behavior was investigated by wear tests using ball-on-disc and pin-on-disc tribometer. The microstructures of the contact surfaces were determined by a scanning electron microscopy before and after the test to study the wear mechanism. Uncoated and coated surfaces after wear test are also subjected to micro-hardness tests. The tribological test results showed that the microhardness, friction and wear resistance of coated Ti-6Al-4V alloys increases by increasing TiO₂ content in the powder composite when other experimental conditions were constant. Finally, Al₂O₃-TiO₂ powder composites for the investigated conditions, both coating samples had satisfactory values of friction and wear resistance, and they could be suitable candidates for Ti–6Al–4V material.

Keywords: HVOF (High Velocity Oxygen Fuel), Al₂O₃-TiO₂, Ti-6Al-4V, tribology

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Authors: Krishnamoorthy Sathiyan, Shanti Gopal Patra, Ronen Bar-Ziv, Tomer Zidki

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Developing efficient non-noble metal catalysts that are cheap and durable for oxygen evolution reaction (OER) is a great challenge. Moreover, altering the electronic structure of the catalyst and structural engineering of the materials provide a new direction for enhancing the OER. Herein, we have successfully synthesized Fe and Co incorporated MoS₂ catalysts, which show improved catalytic activity for OER when compared with MoS₂, Fe-MoS₂, and Co-MoS₂. It was found that at an optimal ratio of Fe and Co, the electronic and structural modification of MoS₂ occurs, which leads to change in orientation and thereby enhances the active catalytic sites on the edges, which are more exposed for OER. The nanocomposites have been well characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray analysis (EDX), Elemental Mapping, transmission electron microscope (TEM), and high-resolution transmission electron microscope (HR-TEM) analysis. Among all, a particular ratio of FeCo-MoS₂ exhibits a much smaller onset with better catalytic current density. The remarkable catalytic activity is mainly attributed to the synergistic effect from the Fe and Co. Most importantly, our work provides an essential insight in altering the electronic structure of MoS₂ based materials by incorporating promoters such as Co and Fe in an optimal amount, which enhances OER activity.

Keywords: electrocatalysts, molybdenum disulfide, oxygen evolution reaction, transition metals

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Authors: Juniarti Yuni

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Simawang area is one of the critical areas (sub-optimal) that experienced drought from climate changes. Potential dry land belonging to sub-optimal in Simawang, West Sumatera, Indonesia not been fully utilized for agricultural cultivation. Simawang village, West Sumatera, Indonesia is formerly known as the rice barn, due to the climate change area is experiencing a drought, so the rice fields that were once productive now a grazing paddock because of lack of water. This study aims to calculate the soil carbon stock in Simawang village, West Sumatera Indonesia. The study was conducted in Simawang village, Tanah Datar regency, West Sumatera from October 2014 until December 2017. The study was conducted on sub-optimal land to be planted with Cymbopogon nardus L. (Sereh wangi in Indonesian language). Composite soil sampling conducted at a depth of 0-20 cm, 20–40 cm. Based on the depth of soil carbon stocks gained higher ground 6473 T/Ha at a depth of 0-20 cm at a depth of 20-40 cm. Efforts to increase soil carbon is expected to be cultivated through Cymbopogon nardus L. planting has been done.

Keywords: climate changes, sereh wangi (Cymbopogon nardus L.), soil carbon stock, sub optimal land

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Authors: Gi-Beom Park, Hyong-Gi Park, Seong-Yong Lee, Jaeho Choi, Seok Hong Min, Tae Kwon Ha

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The Nb silicide-based alloy has the excellent high-temperature strength and relatively lower density than the Ni-based superalloy; therefore, it has been receiving a lot of attention for the next generation high-temperature material. To enhance the high temperature creep property and oxidation resistance, Si was added to the Nb-based alloy, resulting in a multi-phase microstructure with metal solid solution and silicide phase. Since the silicide phase has a low machinability due to its brittle nature, it is necessary to fabricate components using the powder metallurgy. However, powder manufacturing techniques for the alloys have not yet been developed. In this study, we tried to fabricate Nb-based alloy powder by the hydrogenation-dehydrogenation reaction. The Nb-based alloy ingot was prepared by vacuum arc melting and it was annealed in the hydrogen atmosphere for the hydrogenation. After annealing, the hydrogen concentration was increased from 0.004wt% to 1.22wt% and Nb metal phase was transformed to Nb hydride phase. The alloy after hydrogenation could be easily pulverized into powder by ball milling due to its brittleness. For dehydrogenation, the alloy powders were annealed in the vacuum atmosphere. After vacuum annealing, the hydrogen concentration was decreased to 0.003wt% and Nb hydride phase was transformed back to Nb metal phase.

Keywords: Nb alloy, Nb metal and silicide composite, powder, hydrogenation-dehydrogenation reaction

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Authors: Waheed Ahmad Safi, Shunichi Nakamura, Abdul Habib Ghaforzai

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Steel and concrete composite bridge with concrete filled steel I-girder (CFIG) was proposed and FEM and laboratory tests were conducted to analysis bending and shear behavior. The proposed form of structural steel I-section is mainly used at the intermediate support zone by placing infilled concrete into the top and bottom flanges of steel I-section to resist negative bending moment. The bending and shear tests were carried out to find out the significance of CFIG section. The result for test showing that the bending and shear capacity of proposed CFIG is at least 3 times and 2 times greater than conventional steel I-section (IG) respectively. Finite element study was also carried out to ensure the result for laboratory tests due to bending and shear behavior and load transfer behavior of proposed structural form. Finite element result result agreed the test result. A design example was carried out for a four-span continuous highway bridge and design method was established.

Keywords: bending strength, concrete filled steel I-girder, steel I-girder, FEM, limit states design and shear strength

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Authors: Stepan Hysek, Petra Gajdacova

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In recent years, alternative materials, such as annual plants or recycled and waste materials are becoming more and more popular input material for the production of composite materials. They can be used for the production of insulation boards, construction boards or furniture boards. Surface finishing of those boards is essential for utilization in furniture. However, some difficulties could occur during coating of boards from alternative materials; physical and chemical differences from conventional particleboards need to be considered. From the physical aspects, surface soundness and surface roughness mainly determine the quality of the surface. Since surface layers of boards from alternative materials have often lower density, these characteristics could be deteriorated and thus the production process needs to be optimized. Also, chemical reactions of board’s material with coating could be undesirable. The objective of this study is to evaluate the parameters affecting the surface quality of boards made form alternative materials and to find possibilities of the coating of these boards. In this study, boards of particles from rapeseed stems were produced using a laboratory press. Surface soundness, as representatives of mechanical properties and surface roughness, as representative of physical properties, were measured on boards from rapeseed stems. Results clearly indicated that produced boards had lower surface quality than commercially produced particle boards from wood. Therefore, higher thickness of surface coating on rapeseed based boards is needed.

Keywords: coating, surface, annual plant, composites, particleboard

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Authors: K. Kamal

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Structural sandwich panels with core of Advanced Composites Laminates l Honeycombs / PU-foams are used in aerospace applications and are also fabricated for use now in some civil engineering applications. An all Advanced Composites Foot Over Bridge (FOB) system, designed and developed for pedestrian traffic is one such application earlier, may be cited as an example here. During development stage of this FoB, a profile of its decks was then spurred as a single corrugate sheet core sandwiched between two Glass Fibre Reinforced Plastics(GFRP) flat laminates. Once successfully fabricated and used, these decks did prove suitable also to form other structure on assembly, such as, erecting temporary shelters. Such corrugated sheet core profile sandwiched panels were then also tried using the construction materials but any conventional method of construction only posed certain difficulties in achieving the required core profile monolithically within the sandwiched slabs and hence it was then abended. Such monolithic construction was, however, subsequently eased out on demonstration by dispensing building materials mix through a suitably designed multi-dispenser system attached to a 3D Printer. This study conducted at lab level was thus reported earlier and it did include the fabrication of a 3D printer in-house first as ‘3DcMP’ as well as on its functional operation, some required sandwich core profiles also been 3D-printed out producing panels hardware. Once a number of these sandwich panels in single corrugated sheet core monolithically printed out, panels were subjected to load test in an experimental set up as also their structural behavior was studied analytically, and subsequently, these results were correlated as reported in the literature. In achieving the required more depths and also to exhibit further the stronger and creating sandwiched decks of better structural and mechanical behavior, further more complex core configuration such as stack corrugate sheets core with a flat mid plane was felt to be the better sandwiched core. Such profile remained as an outcome that turns out merely on stacking of two separately printed out monolithic units of single corrugated sheet core developed earlier as above and bonded them together initially, maintaining a different orientation. For any required sequential understanding of the structural behavior of any such complex profile core sandwiched decks with special emphasis to study of the effect in the variation of corrugation orientation in each distinct tire in this core, it obviously calls for an analytical study first. The rectangular,simply supported decks have therefore been considered for analysis adopting the ‘Advanced Composite Technology(ACT), some numerical results along with some fruitful findings were obtained and these are all presented here in this paper. From this numerical result, it has been observed that a mid flat layer which eventually get created monolethically itself, in addition to eliminating the bonding process in development, has been found to offer more effective bending resistance by such decks subjected to UDL over them. This is understood to have resulted here since the existence of a required shear resistance layer at the mid of the core in this profile, unlike other bending elements. As an addendum to all such efforts made as covered above and was published earlier, this unique stack corrugate sheet core profile sandwiched structural decks, monolithically construction with ease at the site itself, has been printed out from a 3D Printer. On employing 3DcMP and using some innovative building construction materials, holds the future promises of such research & development works since all those several aspects of a 3D printing in construction are now included such as reduction in the required construction time, offering cost effective solutions with freedom in design of any such complex shapes thus can widely now be realized by the modern construction industry.

Keywords: advance composite technology(ACT), corrugated laminates, 3DcMP, foot over bridge (FOB), sandwiched deck units

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Authors: Getu Dessalegn Asfaw, Yalew Dessalegn Asfaw

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This research aims to examine the chemical composition of bamboo species in Ethiopia under the effect of age and culm height. The chemical composition of bamboo species in Ethiopia has not been investigated so far. The highest to the lowest cellulose and hemicellulose contents are Injibara (Y. alpina), Mekaneselam (Y. alpina), and Kombolcha (B. oldhamii), whereas lignin, extractives, and ash contents are Kombolcha, Mekanesealm, and Injibra, respectively. As a result of this research, the highest and lowest cellulose, hemicelluloses and lignin contents are at the age of 2 and 1 year old, respectively. Whereas extractives and ash contents are decreased at the age of the culm matured. The cellulose, hemicelluloses, lignin, and ash contents of the culm increase from the bottom to top along the height, however, extractive contents decrease from the bottom to top position. The cellulose content of Injibara, Kombolch, and Mekaneselam bamboo was recorded at 51±1.7–53±1.8%, 45±1.6%–48±1.5%, and 48±1.8–51±1.6%, and hemicelluloses content was measured at 20±1.2–23±1.1%, 17±1.0–19±0.9%, and 18±1.0–20±1.0%, lignin content was measured 19±1.0–21±1.1%, 27±1.2–29±1.1%, and 21±1.1–24±1.1%, extractive content was measured 3.9±0.2 –4.5±0.2%, 6.6±0.3–7.8±0.4%, and 4.7±0.2–5.2±0.1%, ash content was measured 1.6±0.1–2.1±0.1%, 2.8±0.1–3.5±0.2%, and 1.9±0.1–2.5±0.1% at the ages of 1–3 years old, respectively. This result demonstrated that bamboo species in Ethiopia can be a source of feedstock for lignocelluloses ethanol and bamboo composite production since they have higher cellulose content.

Keywords: age, bamboo species, culm height, chemical composition

Procedia PDF Downloads 78

Authors: Shimaa A. Higazy, Mohamed S. Selim, Olfat E. El-Azabawy, Abeer A. Hassan

Abstract:

We designed novel epoxy/graphitic carbon nitride (g-C₃N₄) nanocomposite materials as suitable surface coatings. g-C₃N₄ nanosheets were facilely prepared and dispersed in the epoxy resin via solution casting. This research focuses on the mechanical and anticorrosion properties of g-C₃N₄ nanofiller reinforced epoxy nanocomposites. The structures, sizes, and morphologies of designed polymeric nanocomposites and nanofillers were elucidated using various techniques such as FT-IR, NMR, FE-TEM, FE-SEM. The developed nanocomposite was applied as a surface coating by air-assisted spray method. The structure-property relationship was studied for different concentrations of nanofiller in the epoxy matrix. The anticorrosive properties were studied via electrochemical experiments, including potentiodynamic polarization, electrochemical impedance, and open-circuit potential analyses, as well as salt spray test. Mechanical durability was assessed by various methods, such as impact, T-bending, and crosscut tests. Surface heterogeneity, elasticity, and corrosion-resistance features are among the merits of developed composite. The highest improvement was achieved with well dispersion of g-C₃N₄ sheets fillers. This fascinating epoxy nanostructured coating provides a promising anticorrosive coatings for a sustainable future environment.

Keywords: epoxy, nanocomposite, surface coating, anticorrosive properties, mechanical durability

Procedia PDF Downloads 63