Search results for: polymer modified bitumen

Authors: Nino Kupatadze, Shorena Tskhadadze, Mzevinar Bedinashvili, David Tugushi, Ramaz Katsarava

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Surgical device-associated infection and biofilm formation are some of the major problems in biomedicine for today. The losing protection ability of conventional antimicrobial-drugs leads to the challenges in the current antibiotic therapy, the most serious of which is antibiotic resistance. Our strategy to overcome the biofilm formation consists in coating devices with polymeric film containing nanosilver(AgNPs) as a bactericidal agent. Such bionanocomposites are also promising as wound dressing materials. For this purpose, we have developed a new generation of AgNPs containing polymeric composites in which amino acid based biodegradable poly(ester amide)s (PEAs) were served as both matrices and AgNPs stabilizers. The AgNPs were formed by photochemical (daylight) reduction of AgNO3 in ethanol solution. The formation of AgNPs was monitored by coloring the solution in brownish-red and appearance of the absorption maximum at 420-430 nm in UV spectrum. Comparative studies of PEAs with polyvinylpyrrolidone (PVP) as particle stabilizers were carried out. It was found that PVP is better stabilizer in terms of particles yield and stability. Therefore, in subsequent experiments blends of PEAs and PVP were used as stabilizers for fabricating AgNPs. As expected, PVP increased the stabilizing effect and this apparently observed in the UV spectrum of the samples after 7 h daylight irradiation: for pure PVP λmax = 430 nm, D = 2.03, for pure PEA λmax= 420 nm, D = 0.65, and for the blend of PVP and PEA λmax = 435 nm, D = 1.88. Further study of the obtained nanobiocomposites is in progress now.

Keywords: biodegradation, bionanocompositions, polymer, nanosilver

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Authors: Jungho Moon, Myunggon Yoon

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This paper presents an implementation of a configurable UART-to-Ethernet converter using an ARM-based 32-bit microcontroller as well as a dedicated configuration program running on a PC for configuring the operating parameters of the converter. The program was written in Python. Various parameters pertaining to the operation of the converter can be modified by the configuration program through the Ethernet interface of the converter. The converter supports 3 representative asynchronous serial communication protocols, RS-232, RS-422, and RS-485 and supports 3 network modes, TCP/IP server, TCP/IP client, and UDP client. The TCP/IP and UDP protocols were implemented on the microcontroller using an open source TCP/IP protocol stack called lwIP (A lightweight TCP/IP) and FreeRTOS, a free real-time operating system for embedded systems. Due to the use of a real-time operating system, the firmware of the converter was implemented as a multi-thread application and as a result becomes more modular and easier to develop. The converter can provide a seamless bridge between a serial port and an Ethernet port, thereby allowing existing legacy apparatuses with no Ethernet connectivity to communicate using the Ethernet protocol.

Keywords: converter, embedded systems, ethernet, lwIP, UART

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Authors: Liuyao Chai, Colin Clark

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Analysis of 574 participants in a simulated two-person distributive negotiation revealed that the first price 245 (42.7%) of these participants actually asked/offered for the item under negotiation (a used car) differed from the first price they previously stated they intended to ask/offer during their negotiation. This discrepancy between a negotiator’s intended first asking/offer price and his/her actual first asking/offer price had a significant and economically consequential impact on both the course and the outcomes of the negotiations studied. Participants whose actual first price remained the same as their intended first price tended to secure better negotiation outcomes. Moreover, participants who changed their intended first price tended to obtain relatively lower outcomes regardless of whether their modified first announced price had created a negotiating position that was ‘stronger’ or ‘weaker’ than if they had opened with their intended first price. Subsequent investigation of over twenty negotiation behaviours and pre-negotiation perceptual variables within this dataset indicated that the three types of first price announcers—i.e. intended first asking/offer price ‘weakeners’, ‘maintainers’ and ‘strengtheners’— comprised persons who tended to have significantly different pre-negotiation perceptions and behaved in systematically different ways during their negotiation. Typically, the most negative, outcome-compromising consequences of changing, weakening or strengthening an intended first price occurred at the very beginning of a negotiation when participants exchanged their actual first asking/offer prices.

Keywords: business communication, negotiation, persuasion, intended first asking/offer prices, bargaining

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Authors: Fereshteh Ahmadi, Önver Cetrez, Said Zandi, Sharareh Akhavan

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In this paper, we have mapped the coping methods used to address the coronavirus pandemic by members of the academic community. We conducted an anonymous survey of a convenient sample of 674 faculty/staff members and students from September to December 2020. A modified version of the RCOPE scale was used for data collection. The results indicate that both religious and existential coping methods were used by respondents. The study also indicates that even though 71% of in-formants believed in God or another religious figure, 61% reported that they had tried to gain control of the situation directly without the help of God or another religious figure. The ranking of the coping strategies used indicates that the first five methods used by informants were all non-religious coping methods (i.e., secular existential coping methods): regarding life as a part of a greater whole, regarding nature as an important resource, listening to the sound of surrounding nature, being alone and con-templating, and walking/engaging in any activities outdoors giving a spiritual feeling. Our results contribute to the new area of research on academic community’s coping with pandemic-related stress and challenges.

Keywords: academic staff, academics, coping strategies, coronavirus epidemic, higher education.

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Authors: Bassim Shaheen Bachy, Jörg Franke

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In this study, a three dimensional numerical heat transfer model has been used to simulate the laser structuring of polymer substrate material in the Three-Dimensional Molded Interconnect Device (3D MID) which is used in the advanced multi-functional applications. A finite element method (FEM) transient thermal analysis is performed using APDL (ANSYS Parametric Design Language) provided by ANSYS. In this model, the effect of surface heat source was modeled with Gaussian distribution, also the effect of the mixed boundary conditions which consist of convection and radiation heat transfers have been considered in this analysis. The model provides a full description of the temperature distribution, as well as calculates the depth and the width of the groove upon material removal at different set of laser parameters such as laser power and laser speed. This study also includes the experimental procedure to study the effect of laser parameters on the depth and width of the removal groove metal as verification to the modeled results. Good agreement between the experimental and the model results is achieved for a wide range of laser powers. It is found that the quality of the laser structure process is affected by the laser scan speed and laser power. For a high laser structured quality, it is suggested to use laser with high speed and moderate to high laser power.

Keywords: laser structuring, simulation, finite element analysis, thermal modeling

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Authors: Mohamed Sanad, Noha Hassan

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A low wind-load light-weight broad-band multi-beam base station antenna has been developed. It can generate any required number of beams with the required beamwidths. It can have horizontal and vertical sectorization at the same time. Vertical sectorization doubles the overall number of beams. It will be very valuable in LTE-A and 5G. It can be used to serve vertically split inner and outer cells, which improves system performance. The intersection between the beams of the proposed multi-beam antenna can be controlled by optimizing the design parameters of the antenna. The gain at the points of intersection between the beams, the null filling and the overlap between the beams can all be modified. The proposed multi-beam base station antenna can cover an unlimited number of wireless applications, regardless of their frequency bands. It can simultaneously cover all, current and future, wireless technology generations such as 2G, 3G, 4G (LTE), --- etc. For example, in LTE, it covers the bands 450-470 MHz, 690-960 MHz, 1.4-2.7 GHz and 3.3-3.8 GHz. It has at least 2 ports for each band in each beam for ±45° polarizations. It can include up to 72 ports or even more, which could facilitate any further needed capacity expansions.

Keywords: base station antenna, multi-beam antenna, smart antenna, vertical sectorization

Procedia PDF Downloads 265

Authors: T. Moremedi, L. Katata-Seru, S. Sardar, A. Bandyopadhyay, E. Makhado, M. Joseph Hato

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The rapid industrialisation and population growth have led to a steady fall in freshwater supplies worldwide. As a result, water systems are affected by modern methods upon use due to secondary contamination. The application of novel adsorbents derived from natural polymer holds a great promise in addressing challenges in water treatment. In this study, the UV irradiation technique was used to prepare acrylamide (AAm) monomer, and acrylic acid (AA) monomer grafted xanthan gum (XG) copolymer. Furthermore, the factors affecting rhodamine B (RhB) adsorption from aqueous media, such as pH, dosage, concentration, and time were also investigated. The FTIR results confirmed the formation of graft copolymer by the strong vibrational bands at 1709 cm^-1 and 1612 cm^-1 for AA and AAm, respectively. Additionally, more irregular, porous and wrinkled surface observed from SEM of XG-g-AAm/AA indicated copolymerization interaction of monomers. The optimum conditions for removing RhB dye with a maximum adsorption capacity of 313 mg/g at 25 ⁰C from aqueous solution were pH approximately 5, initial dye concentration = 200 ppm, adsorbent dose = 30 mg. Also, the detailed investigation of the isothermal and adsorption kinetics of RhB from aqueous solution showed that the adsorption of the dye followed a Freundlich model (R² = 0.96333) and pseudo-second-order kinetics. The results further indicated that this absorbent based on XG had the universality to remove dye through the mechanism of chemical adsorption. The outstanding adsorption potential of the grafted copolymer could be used to remove cationic dyes from aqueous solution as a low-cost product.

Keywords: xanthan gum, adsorbents, rhodamine B, Freundlich

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Authors: Venkat Garigapati

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Cell-based therapies are limited due to underlying host immune system activity. Microencapsulation of living cells to overcome this issue has some serious drawbacks, such as limitations of nutrient and oxygen diffusion, which pose a threat to the function and longevity of cells. The conformal coating could overcome the issues which are generally involved in traditional microencapsulation. Some of the theoretical advantages of conformal coating include superior nutrient and oxygen supply to cells, prolonged lifespan, improved drug-secreting cell functionality and an opportunity to load high cell doses in small volumes. Despite several advantages to the conformal coating, there are no suitable methods available to apply to living cells. The ultra-thin conformal coating was achieved utilizing click-reactive methacryloyloxyethyl phosphorylcholine (MPC) polymers, which are capable of specifically reacting one polymer to another at neutral pH in the aqueous isotonic system at the desired temperature suitable for living cells without the need of deleterious initiators. ARPE-19 (Adult Retinal Pigment Epithelial cell line-19) cell-spheroids and rat pancreatic islets were used in the formulation studies. The in vitro studies of coated ARPE-19 cell-spheroids and rat islets indicate that the coat was intact; cells were viable and functioning. The in vitro study results revealed that the conformal coating technology seems promising and in vivo studies are being planned.

Keywords: cells, hydrogel, conformal coating, microencapsulation, insulin

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Authors: Ziyad S. Haidar

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Millions of teeth are removed annually, and dental extraction is one of the most commonly performed surgical procedures globally. Whether due to caries, periodontal disease or trauma, exodontia and the ensuing wound healing and bone remodeling processes of the resultant socket (hole in the jaw bone) usually result in serious deformities of the residual alveolar osseous ridge and surrounding soft tissues (reduced height/width). Such voluminous changes render the placement of a proper conventional bridge, denture or even an implant-supported prosthesis extremely challenging. Further, most extractions continue to be performed with no regard for preventing the onset of alveolar osteitis (also known as dry socket, a painful and difficult-to-treat/-manage condition post-exodontia). Hence, such serious resorptive morphological changes often result in significant facial deformities and a negative impact on the overall Quality of Life (QoL) of patients (and oral health-related QoL), alarming, particularly for the geriatric with compromised healing and in light of the thriving longevity statistics. Opportunity: Despite advances in tissue/wound grafting, serious limitations continue to exist, including efficacy and clinical outcome predictability, cost, treatment time, expertise and risk of immune reactions. For cases of dry sockets, specifically, the commercially-available and often-prescribed home remedies are highly lacking. Indeed, most are not recommended for use anymore. Alveogyl is a fine example. Hence, there is a great market demand and need for alternative solutions. Solution: Herein, SockGEL/PLUG (patent pending), an all-natural, drug-free and injectable stimuli-responsive hydrogel, was designed, formulated, characterized and evaluated as an osteogenic, angiogenic, anti-microbial and pain-soothing suture-free intra-alveolar dressing, safe and efficacious for use in several oro-dental and cranio-maxillo-facial interventional applications; for example: in fresh dental extraction sockets, immediately post-exodontia. It is composed of FDA-approved, biocompatible and biodegradable polymers, self-assembled electro-statically to formulate a scaffolding matrix to (a) prevent the onset of alveolar osteitis via securing the fibrin-clot in situ and protecting/sealing the socket from contamination/infection; and (b) endogenously promote/accelerate wound healing and bone remodeling to preserve the volume of the alveolus. Findings: The intrinsic properties of the SockGEL/PLUG hydrogel were evaluated physico-chemico-mechanically for safety (cell viability), viscosity, rheology, bio-distribution and essentially, capacity to induce wound healing and osteogenesis (small defect, in vivo) without any signaling cues from exogenous cells, growth factors or drugs. The performed animal model of cranial critical-sized and non-vascularized bone defects shall provide vitally critical insights into the role and mechanism of the employed natural bio-polymer blend and gel product in endogenous reparative regeneration of soft tissues and bone morphogenesis. Alongside, the fine-tuning of our modified formulation method will further tackle appropriateness, reproducibility, scalability, ease and speed in producing stable, biodegradable and sterilizable stimuli (thermo-sensitive and photo-responsive) matrices (3-dimensional interpenetrating yet porous polymeric network) suitable for an intra-socket application, and beyond. Conclusions and Perspective: Findings are anticipated to provide sufficient evidence to translate into pilot clinical trials and validate the bionanomaterial before engaging the market for feasibility, acceptance and cost-effectiveness studies. The SockGEL/PLUG platform is patent pending: SockGEL is a bio-inspired drug-free hydrogel; SockPLUG is a drug-loaded hydrogel designed for complex indications.

Keywords: hydrogel, injectable, dentistry, craniomaxillofacial complex, bioinspired, nanobiotechnology, biopolymer, sol-gel, stimuli-responsive, matrix, tissue engineering, regenerative medicine

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Authors: Laredo Alcalá Elan Iñaky, Hernandez Castillo Daniel, Martinez Hernandez José Luis, Arredondo Valdes Roberto, Gonzalez Gallegos Esmeralda, Anguiano Cabello Julia Cecilia

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Plant hormones are a group of molecules that control different processes ranging from the growth and development of the plant until their response to biotic and abiotic stresses. In this study, the capacity of production of various phytohormones was evaluated from a strain of Botryodiplodia theobromae by liquid fermentation system using the modified Mierch medium added with a hydrolyzate compound of mead all in a reactor without agitation at 28 °C for 15 days. Quantification of the metabolites was performed using high performance liquid chromatography techniques. The results showed that a microbial broth with at least five different types of plant hormones was obtained: gibberellic acid, zeatin, kinetin, indoleacetic acid and jasmonic acid, the last one was higher than the others metabolites produced. The production of such hormones using a single type of microorganism could be in the future a great alternative to reduce production costs and similarly reduce the use of synthetic chemicals.

Keywords: biosystem, plant hormones, Botryodiplodia theobromae, fermentation

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Authors: Dhivya Balakrishnan, Dhamodharan Shanmugam

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Multilevel converters offer high power capability, associated with lower output harmonics and lower commutation losses. Their main disadvantage is their complexity requiring a great number of power devices and passive components, and a rather complex control circuitry. This paper proposes a single-phase seven-level inverter for grid connected PV systems, With a novel pulse width-modulated (PWM) control scheme. Three reference signals that are identical to each other with an offset that is equivalent to the amplitude of the triangular carrier signal were used to generate the PWM signals. The inverter is capable of producing seven levels of output-voltage levels from the dc supply voltage. This paper proposes a new multilevel inverter topology using an H-bridge output stage with two bidirectional auxiliary switches. The new topology produces a significant reduction in the number of power devices and capacitors required to implement a multilevel output using the asymmetric cascade configuration.

Keywords: asymmetric cascade configuration, H-Bridge, multilevel inverter, Pulse Width Modulation (PWM)

Procedia PDF Downloads 362

Authors: Youssef Babkrani, S. Hiyani, A. Naddami, K. Choukri, M. Hilal

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Power Quality has been a problem ever since electrical power was invented and in recent years, it has become the main interest of researchers who are still concerned about finding ways to reduce its negative influence on electrical devices. In this paper we aim to improve the power quality output for H- bridge multilevel inverter used with solar Photovoltaic (PV) panels, we propose a new switching technique that uses a pulse width modulation method (PWM) aiming to reduce the harmonics. This new method introduces a sinusoidal wave compared with modified trapezoidal carriers used to generate the pulses. This new trapezoid carrier waveform is being implemented with different sinusoidal PWM dispositions such as phase disposition (PWM PD), phase opposition disposition (PWM POD), and (PWM APOD) alternative phase opposition disposition and compared with the conventional ones. Using Matlab Simulink R2014a the line voltage and total harmonic distortions (THD) simulated and the quality are increased in spite of variations of DC introduced.

Keywords: carrier waveform, phase disposition (PD), phase opposition disposition (POD), alternative phase opposition disposition (APOD), total harmonics distortion (THD)

Procedia PDF Downloads 288

Authors: Mohammad Reza Dahmardeh Ghaleno, Mohammad Nohtani, Saeedeh Khaledi

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Hydrological models are applied to simulation and prediction floods in watersheds. WetSpa is a distributed, continuous and physically model with daily or hourly time step that explains of precipitation, runoff and evapotranspiration processes for both simple and complex contexts. This model uses a modified rational method for runoff calculation. In this model, runoff is routed along the flow path using Diffusion-Wave Equation which depend on the slope, velocity and flow route characteristics. Garmabrood watershed located in Mazandaran province in Iran and passing over coordinates 53° 10´ 55" to 53° 38´ 20" E and 36° 06´ 45" to 36° 25´ 30"N. The area of the catchment is about 1133 km2 and elevations in the catchment range from 213 to 3136 m at the outlet, with average slope of 25.77 %. Results of the simulations show a good agreement between calculated and measured hydrographs at the outlet of the basin. Drawing upon Nash-Sutcliffe Model Efficiency Coefficient for calibration periodic model estimated daily hydrographs and maximum flow rate with an accuracy up to 61% and 83.17 % respectively.

Keywords: watershed simulation, WetSpa, runoff, flood prediction

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Authors: Noufe H. Aljahdaly

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The Laplace homotopy perturbation method (LHPM) is an approximate method that help to compute the approximate solution for partial differential equations. The method has been used for solving several problems in science. It requires the initial condition, so it solves the initial value problem. In physics, when some important terms are taken in account, we may obtain non-integrable partial differential equations that do not have analytical integrals. This type of PDEs do not have exact solution, therefore, we need to compute the solution without initial condition. In this work, we improved the LHPM to be able to solve non-integrable problem, especially the damped PDEs, which are the PDEs that include a damping term which makes the PDEs non-integrable. We improved the LHPM by setting a perturbation parameter and an embedding parameter as the damping parameter and using the initial condition for damped PDE as the initial condition for non-damped PDE.

Keywords: non-integrable PDEs, modified Kawahara equation;, laplace homotopy perturbation method, damping term

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Authors: B. Almassri, F. Almahmoud, R. Francois

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Near surface mounted reinforcement (NSM) technique is one of the promising techniques used nowadays to strengthen reinforced concrete (RC) structures. In the NSM technique, the Carbon Fibre Reinforced Polymer (CFRP) rods are placed inside pre-cut grooves and are bonded to the concrete with epoxy adhesive. This paper studies the non-classical mode of failure ‘the separation of concrete cover’ according to experimental and numerical FE modelling results. Experimental results and numerical modelling results of a 3D finite element (FE) model using the commercial software Abaqus and 2D FE model FEMIX were obtained on two beams, one corroded (25 years of corrosion procedure) and one control (A1CL3-R and A1T-R) were each repaired in bending using NSM CFRP rod and were then tested up to failure. The results showed that the NSM technique increased the overall capacity of control and corroded beams despite a non-classical mode of failure with separation of the concrete cover occurring in the corroded beam due to damage induced by corrosion. Another FE model used external steel stirrups around the repaired corroded beam A1CL3-R which failed with the separation of concrete cover, this model showed a change in the mode of failure form a non-classical mode of failure by the separation of concrete cover to the same mode of failure of the repaired control beam by the crushing of compressed concrete.

Keywords: corrosion, repair, Reinforced Concrete, FEM, CFRP, FEMIX

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Authors: Punit Kumar, Niraj Kumar

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The traction behavior of lubricants with the linear pressure-viscosity response in EHL line contacts is investigated numerically for smooth as well as rough surfaces. The analysis involves the simultaneous solution of Reynolds, elasticity and energy equations along with the computation of lubricant properties and surface temperatures. The temperature modified Doolittle-Tait equations are used to calculate viscosity and density as functions of fluid pressure and temperature, while Carreau model is used to describe the lubricant rheology. The surface roughness is assumed to be sinusoidal and it is present on the nearly stationary surface in near-pure sliding EHL conjunction. The linear P-V oil is found to yield much lower traction coefficients and slightly thicker EHL films as compared to the synthetic oil for a given set of dimensionless speed and load parameters. Besides, the increase in traction coefficient attributed to surface roughness is much lower for the former case. The present analysis emphasizes the importance of employing realistic pressure-viscosity response for accurate prediction of EHL traction.

Keywords: EHL, linear pressure-viscosity, surface roughness, traction, water/glycol

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Authors: T. H. Huang, C. L. Fern, Y. K. Tseng

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The design and reliability of solar photovoltaic modules are crucial to the development of solar energy, and efforts are still being made to extend the life of photovoltaic modules to improve their efficiency because natural aging is time-consuming and does not provide manufacturers and investors with timely information, accelerated aging is currently the best way to estimate the life of photovoltaic modules. Bifacial solar cells not only absorb light from the front side but also absorb light reflected from the ground on the back side, surpassing the performance of single-sided solar cells. Due to the asymmetry of the two sides of the light, in addition to the difference in photovoltaic conversion efficiency, there will also be differences in heat distribution, which will affect the electrical properties and material structure of the bifacial solar cell itself. In this study, there are two types of experimental samples: packaged and unpackaged and then irradiated with UVC light sources and halogen lamps for accelerated aging, as well as a control group without aging. After two weeks of accelerated aging, the bifacial solar cells were visual observation, and infrared thermal images were taken; then, the samples were subjected to IV measurement, and samples were taken for SEM, Raman, and XRD analyses in order to identify the defects that lead to failure and chemical changes, as well as to analyze the reasons for the degradation of their characteristics. From the results of the analysis, it is found that aging will cause carbonization of the polymer material on the surface of bifacial solar cells, and the crystal structure will be affected.

Keywords: bifacial solar cell, accelerated aging, temperature, characterization, electrical measurement

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Authors: Ahmed A. Khamis, Sherif A. Ibrahim, Mahmoud El Khatieb, Mohamed A. Barakat

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Parametric design is an icon of the modern architectural that facilitate taking complex design decisions counting on altering various design parameters. Double skin facades are one of the parametric applications for using parametric designs. This paper opts to enhance different daylight parameters of a selected case study office building in Cairo using parametric double skin facade. First, the design and optimization process executed utilizing Grasshopper parametric design software which is a plugin in rhino. The daylighting performance of the base case building model was compared with the one used the double façade showing an enhancement in daylighting performance indicators like glare and task illuminance in the modified model, execution drawings are made for the optimized design to be executed through Revit, followed by computerized digital fabrication stages of the designed model with various scales to reach the final design decisions using Simplify 3D for mock-up digital fabrication

Keywords: parametric design, double skin facades, digital fabrication, grasshopper, simplify 3D

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Authors: Sifatullah Bahij, Safiullah Omary, Francoise Feugeas, Amanullah Faqiri

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Reinforced concrete (RC) is commonly used material in the construction sector, due to its low-cost and durability, and allowed the architectures and designers to construct structural members with different shapes and finishing. Usually, RC members are designed to sustain service loads efficiently without any destruction. However, because of the faults in the design phase, overloading, materials deficiencies, and environmental effects, most of the structural elements will require maintenance and repairing over their lifetime. Therefore, strengthening and repair of the deteriorated and/or existing RC structures are much important to extend their life cycle. Various techniques are existing to retrofit and strengthen RC structural elements such as steel plate bonding, external pre-stressing, section enlargement, fiber reinforced polymer (FRP) wrapping, etc. Although these configurations can successfully improve the load bearing capacity of the beams, they are still prone to corrosion damage which results in failure of the strengthened elements. Therefore, many researchers used fiber reinforced cementitious materials due to its low-cost, corrosion resistance, and result in improvement of the tensile and fatigue behaviors. Various types of cementitious materials have been used to strengthen or repair structural elements. This paper has summarized to accumulate data regarding on previously published research papers concerning the torsional behaviors of RC beams strengthened by various types of cementitious materials.

Keywords: reinforced concrete beams, strengthening techniques, cementitious materials, torsional strength, twisting angle

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Authors: Kunal Krishna Das, Eddie S. S. Lam

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Preplaced Aggregate Concrete (PAC) is produced by first placing the coarse aggregate into the formwork, followed by injection of grout to fill in the voids in between the coarse aggregates. In this study, tests were carried out to determine the effects of supplementary cementitious materials on the properties of PAC. Cement was partially replaced by ground granulated blast furnace slag (GGBS) and silica fume (SF) at different proportions. Grout properties were determined by the flow cone test and compressive strength test. Grout proportion was optimized statistically. It was applied to form PAC. Hardened properties of PAC, comprising compressive strength, splitting tensile strength, chloride-ion penetration and drying shrinkage, were evaluated. GGBS enhanced the flowability of the grout, whereas SF enhanced the strength of PAC. Both GGBS and SF improved the resistance to chloride-ion penetration with the drawback of increased drying shrinkage. Nevertheless, drying shrinkage was within the range to be classified as low shrinkage concrete.

Keywords: factorial design, ground granulated blast furnace slag, preplaced aggregate concrete, silica fume

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

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

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

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Authors: Rishav Shrestha, Yong Zhang

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The Anti-Stoke upconversion process has been used extensively for bioimaging and is recently being used for photoactivated therapy in cancer utilizing upconversion nanoparticles (UCNs). The UCNs have an excitation band at 980nm; 980nm laser excitation used to produce UV/Visible emissions also produce a heating effect. Light-to-heat conversion has been observed in nanoparticles(NPs) doped with neodymium(Nd) or ytterbium(Yb)/erbium(Er) ions. Despite laser-induced heating in Rare-earth doped NPs being proven to be a relatively efficient process, only few attempts to use them as photothermal agents in biosystems have been made up to now. Gold nanoparticles and carbon nanotubes are the most researched and developed for photothermal applications. Both have large heating efficiency and outstanding biocompatibility. However, they show weak fluorescence which makes them harder to track in vivo. In that regard, UCNs are attractive due to their excellent optical features in addition to their light-to-heat conversion and excitation by NIR, for imaging and spatiotemporally releasing drugs. In this work, we have utilized a simple method to coat Nd doped UCNs with thermoresponsive polymer PNIPAM on which 4-Hydroxytamoxifen (4-OH-T) is loaded. Such UCNs demonstrate a high loading efficiency and low leakage of 4-OH-T. Encouragingly, the release of 4-OH-T can be modulated by varying the power and duration of the NIR. Such UCNs were then used to demonstrate imaging and controlled photothermal release of 4-OH-T in MCF-7 breast cancer cells.

Keywords: cancer therapy, controlled release, photothermal release, upconversion nanoparticles

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Authors: Neha Babbar, S. Van Roy, W. Dejonghe, S. Sforza, K. Elst

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Pectic oligosaccharides (a class of prebiotics) are non-digestible carbohydrates which benefits the host by stimulating the growth of healthy gut micro flora. Production of prebiotic pectic oligosaccharides (POS) from pectin rich agricultural residues involves a cutting of long chain polymer of pectin to oligomers of pectin while avoiding the formation of monosaccharides. The objective of the present study is to develop a two-step continuous biocatalytic membrane reactor (MER) for the continuous production of POS (from sugar beet pulp) in which conversion is combined with separation. Optimization of the ratio of POS/monosaccharides, stability and productivities of the process was done by testing various residence times (RT) in the reactor vessel with diluted (10 RT, 20 RT, and 30 RT) and undiluted (30 RT, 40 RT and 60 RT) substrate. The results show that the most stable processes (steady state) were 20 RT and 30 RT for diluted substrate and 40 RT and 60 RT for undiluted substrate. The highest volumetric and specific productivities of 20 g/L/h and 11 g/gE/h; 17 g/l/h and 9 g/gE/h were respectively obtained with 20 RT (diluted substrate) and 40 RT (undiluted substrate). Under these conditions, the permeates of the reactor test with 20 RT (diluted substrate) consisted of 80 % POS fractions while that of 40 RT (undiluted substrate) resulted in 70% POS fractions. A two-step continuous biocatalytic MER for the continuous POS production looks very promising for the continuous production of tailor made POS. Although both the processes i.e 20 RT (diluted substrate) and 40 RT (undiluted substrate) gave the best results, but for an Industrial application it is preferable to use an undiluted substrate.

Keywords: pectic oligosaccharides, membrane reactor, residence time, specific productivity, volumetric productivity

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Authors: Zahra Azizi, Ashkan Karbasi, Farzin Firouzian, Sara Soleimani Asl, Akram Ranjbar

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Background: One of the most often used herbicides in agriculture is paraquat (PQ), which is very harmful to both people and animals. Chitosan is a well-known, non-toxic polymer commonly used in preparing particles via ionotropic gelation facilitated by negatively charged agents such as sodium alginate. This study aimed to compare the effects of PQ and nanoparaquat (PQNPs) on liver function in male rats. Materials & Methods: Rats were exposed to PQ & PQNPs (4 mg/kg/day, intraperitoneally) for seven days. Then, rats were anesthetized, and serum and liver samples were collected. Later, enzymatic activities such as alanine transaminase (ALT), aspartate transaminase (AST), and alkaline phosphatase (ALP) in serum and oxidative stress biomarkers such as lipid peroxidation (LPO), total antioxidant capacity (TAC) and total thiol groups (TTG) levels in liver tissue were measured by colorimetric methods. Also, histological changes in the liver were evaluated. Results: PQ altered the levels of ALT, AST, and ALP while inducing oxidative stress in the liver. Additionally, liver homogenates with PQ exposure had challenged LPO, TAC, and TTG levels. The severe liver damage is indicated by a significant increase in the enzyme activity of AST, ALT, and ALP in serum. According to the results of the current study, PQNPs, as compared to PQ and the control group, lowered ALT, AST, ALP, and LPO levels while increasing TAC and TTG levels. Conclusion: According to biochemical and histological investigations, PQ loaded in chitosan-alginate particles is more efficient than free PQ at reducing liver toxicity.

Keywords: paraquat, paraquat nanoparticles, liver, oxidative stress

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Authors: Kun Qi, Yuman Zhou, Jianxin He

Abstract:

A facile fabrication strategy via electrospinning and followed by in situ polymerization to fabricate a highly stretchable and conductive Poly(3,4-ethylenedioxythiophene)/Polyurethane (PEDOT/PU) nanofibrous membrane is reported. PU nanofibers were prepared by electrospinning and then PEDOT was coated on the plasma modified PU nanofiber surface via in-situ polymerization to form flexible PEDOT/PU composite nanofibers with conductivity. The results show PEDOT is successfully synthesized on the surface of PU nanofiber and PEDOT/PU composite nanofibers possess skin-core structure. Furthermore, the experiments indicate the optimal technological parameters of the polymerization process are as follow: The concentration of EDOT monomers is 50 mmol/L, the polymerization time is 24 h and the temperature is 25℃. The PEDOT/PU nanofibers exhibit excellent electrical conductivity ( 27.4 S/cm). In addition, flexible sensor made from conductive PEDOT/PU nanofibers shows highly sensitive response towards tensile strain and also can be used to detect finger motion. The results demonstrate promising application of the as-obtained nanofibrous membrane in flexible wearable electronic fields.

Keywords: electrospinning, polyurethane, PEDOT, conductive nanofiber, flexible senor

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Authors: Gaurav Verma

Abstract:

Organoclay loaded (0-5 weight %) polyester-urethane (PU) coatings were prepared with a branched hydroxyl-bearing polyester and an aliphatic poly-isocyanate. TEM micrographs show partial exfoliation and intercalation of clay platelets in organoclay-polyester dispersions. AFM surface images reveals that the PU hard domains tend to regularise and also self-organise into spherical shapes of sizes 50 nm (0 wt %), 60 nm (2 wt %) and 190 nm (4 wt %) respectively. IR analysis shows that PU chains have increasing tendency to interact with exfoliated clay platelets through hydrogen bonding. This interaction strengthens inter-chain linkages in PU matrix and hence improves anti-ageing properties. 1000 hours of accelerated weathering was evaluated by ATR spectroscopy, while yellowing and overall discoloration was quantified by the Δb* and ΔE* values of the CIELab colour scale. Post-weathering surface properties also showed improvement as the loss of thickness and reduction in gloss in neat PU was 25% and 42%; while it was just 3.5% and 14% respectively for the 2 wt% nanocomposite coating. This work highlights the importance of modifying surface and bulk properties of PU coatings at nanoscale, which led to improved performance in accelerated weathering conditions.

Keywords: coatings, AFM, ageing, spectroscopy

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Authors: S. Patel, T. Mitra, R. Dubey, J. Keller

Abstract:

In the present investigations, an attempt has been made to study the charge storage mechanism and mechanism for the flow of transient charging and discharging current in an amorphous polymer (Polysulfone) (PSF) and a semi-crystalline polar Polyvinylidene fluoride (PVDF) blends in ratio PSF: PVDF: 80:20;85:15;90:10 and 95:05 at various poling temperatures (i.e. 60, 75, 90 and 1150C) and with field strength (100, 150, 200 and 250kVcm⁻¹). Thermally stimulated depolarizing current TSDC thermograms for (Polysulfone (PSF) and Polyvinylidene fluoride (PVDF) Blends sample have been obtained under different polarizing conditions. Peaks are found at high-temperature side. The variation of structure on blending and poling condition affects the magnitude of TSDC. The activation energy values have been calculated using the initial rise method of Garlick and Gibson. The transient current with the similar polarizing condition has been investigated over a period of 3X10³ sec. The observed characteristics obey Curie-Von Schweidler law in the studied temperature range. The charging current versus polarizing temperature curves at a constant time, i.e., isochronal current characteristics were studied and the activation energies were calculated. The activation energy in transient thermograms calculated by different methods is in good agreement with the values obtained from TSDC studies.

Keywords: activation energy, polysulfone (PSF), polyvinylidenefluoride (PVDF), thermally stimulated depolarizing current (TSDC)

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Authors: D. Benmoussa, H. Hannache, O. Cherkaoui

Abstract:

In textiles, the major interest in microencapsulation is currently in the application of durable fragrances, skin softeners, phase-change materials, antimicrobial agents and drug delivery systems onto textile materials. In our research “Polyethylene Glycol” was applied as phase change material and it was encapsulated in polymethacrylic acid (PMA) by radical polymerization in suspension of methacrylic acid in presence of N,N'-methylenebisacrylamide (MBAM) as crosslinking agent. Thereafter the obtained microcapsule was modified by amidation with ethylenediamine as a spacer molecule. At the end of this spacer trichlorotriazine reactive group was fixed. Microcapsules were grafted onto cotton textile substrate. The surface morphologies of the microencapsulated phase change materials (micro PCMs) were studied by scanning electron microscopy (SEM). Thermal properties, thermal reliabilities and thermal stabilities of the as-prepared micro PCMs were investigated by differential scanning calorimetry (DSC) and thermogravmetric analysis (TGA). The results obtained show the obtaining microcapsules with a mean diameter of 10 µm and the resistance of the microcapsules is demonstrated by thermal analysis.

Keywords: energy storage, microencapsulation, phase-change materials, thermogravmetric analysis (TGA)

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Authors: Sarekha Woranuch, Rangrong Yoksan

Abstract:

Active packaging has been developed based on the incorporation of certain additives, in particular antimicrobial and antioxidant agents, into packaging systems to maintain or extend product quality and shelf-life. Ferulic acid is one of the most effective natural phenolic antioxidants, which has been used in food, pharmaceutical and active packaging film applications. However, most phenolic compounds are sensitive to oxygen, light and heat; its activities are thus lost during product formulation and processing. Grafting ferulic acid onto polymer is an alternative to reduce its loss under thermal processes. Therefore, the objectives of the present research were to study the thermal stability of ferulic acid after grafting onto chitosan, and to investigate the possibility of using ferulic acid-grafted chitosan (FA-g-CTS) as an antioxidant for active biodegradable packaging film. FA-g-CTS was incorporated into biodegradable film via a two-step process, i.e. compounding extrusion at temperature up to 150 °C followed by blown film extrusion at temperature up to 175 °C. Although incorporating FA-g-CTS with a content of 0.02–0.16% (w/w) caused decreased water vapor barrier property and reduced extensibility, the films showed improved oxygen barrier property and antioxidant activity. Radical scavenging activity and reducing power of the film containing FA-g-CTS with a content of 0.04% (w/w) were higher than that of the naked film about 254% and 94%, respectively. Tensile strength and rigidity of the films were not significantly affected by adding FA-g-CTS with a content of 0.02–0.08% (w/w). The results indicated that FA-g-CTS could be potentially used as an antioxidant for active packaging film.

Keywords: active packaging film, antioxidant activity, chitosan, ferulic acid

Procedia PDF Downloads 507

Authors: Ashish Kumar, T. Venkatappa Rao, Subhendu Ray Chowdhury, S. V. S. Ramana Reddy

Abstract:

The main objective of this work is to determine the influence of electron beam irradiation on thermal and mechanical properties of Poly (lactic acid) (PLA)/Poly (ethylene-co-glycidyle methacrylate) (PEGM)/Hexagonal boron nitride (HBN) blend-composites. To reduce the brittleness and improve the toughness of PLA, the PLA/PEGM blend is prepared by using twin-screw Micro compounder. However, the heat deflection temperature (HDT) and other tensile properties were reduced. The HBN has been incorporated into the PLA/PEGM blend as part per hundred i.e. 5 phr and 10phr to improve the HDT. The prepared specimens of blend and blend-composites were irradiated to high energy (4.5 MeV) electron beam (E-beam) at different radiation doses to introduce the cross linking among the polymer chains and uniform dispersion of HBN particles in the PLA/PEGM/HBN blend-composites. The further improvement in the notched impact strength and HDT have been achieved in the case of PLA/PEGM/HBN blend-composites. The irradiated PLA/PEGM/HBN 5phr blend composite shows high notched impact strength and HDT as compared to other unirradiated and E-beam irradiated blend and blend-composites. The improvements in the yield strength and tensile modulus have also been noticed in the case of E-beam irradiated PLA/PEGM/HBN blend-composites as compared to unirradiated blend-composites.

Keywords: blend-composite, e-beam, HDT, PEGM, PLA

Procedia PDF Downloads 191