Search results for: oxygen reduction reaction (ORR)

Authors: Leticia Leandro Rade, Amanda Silva de Sousa, Suman Das, Wesley Generoso, Mayara Chagas Ávila, Plinio Salmazo Vieira, Antonio Bonomi, Gabriela Persinoti, Mario Tyago Murakami, Thomas Michael Makris, Leticia Maria Zanphorlin

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Alkenes have an economic appeal, especially in the biofuels field, since they are precursors for drop-in biofuels production, which have similar chemical and physical properties to the conventional fossil fuels, with no oxygen in their composition. After the discovery of the first P450 CYP152 OleTJE in 2011, reported with its unique property of decarboxylating fatty acids (FA), by using hydrogen peroxide as a cofactor and producing 1-alkenes as the main product, the scientific and technological interest in this family of enzymes vastly increased. In this context, the present work presents a new decarboxylase (OleTRN) with low similarity with OleTJE (32%), its biochemical characterization, and structure elucidation. As main results, OleTRN presented a high yield of expression and purity, optimum reaction conditions at 35 °C and pH from 6.5 to 8.0, and higher specificity for oleic acid. Besides that, structure-guided mutations were performed and according to the functional characterizations, it was observed that some mutations presented different specificity and chemoselectivity by varying the chain-length of FA substrates from 12 to 20 carbons. These results are extremely interesting from a biotechnological perspective as those characteristics could diversify the applications and contribute to designing better cytochrome P450 decarboxylases. Considering that peroxygenases have the potential activity of decarboxylating and hydroxylating fatty acids and that the elucidation of the intriguing mechanistic involved in the decarboxylation preferential from OleTJE is still a challenge, the elucidation of OleTRN structure and the functional characterizations of OleTRN and its mutants contribute to new information about CYP152. Besides that, the work also contributed to the discovery of a new decarboxylase with a different selectivity profile from OleTJE, which allows a wide range of applications.

Keywords: P450, decarboxylases, alkenes, biofuels

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Authors: Samuel Mejorado

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C. Reinahrdtii serves as one of the most promising organisms from which to obtain biological hydrogen. However, its production catalyst, [FeFe]-hydrogenase, is largely inhibited by the presence of oxygen. In recent years, researchers have identified a Proton Gradient Regulation 5 (PGR5) deficient mutant, which shows enhanced respiration and lower accumulations of oxygen within the system. In this research, we investigated the effects of varying nutrient conditions on PGR5 mutants' ability to produce hydrogen. After growing PGR5 mutants in varying nutrient conditions under 55W fluorescent lamps at 30℃ with constant stirring at 200 rpm, a common water displacement method was utilized to obtain a definitive volumetric reading of hydrogen produced by these mutants over a period of 12 days. After the trials, statistical t-tests and ANOVAs were performed to better determine the effect which nutrient conditions have on PGR5 mutants' ability to produce hydrogen. In this, we report that conditions of sulfur deprivation most optimally enhanced hydrogen production within these mutants, with groups grown under these conditions demonstrating the highest production capacity over the entire 12-day period. Similarly, it was found that when grown under conditions of nitrogen deprivation, a favorable shift towards carbon fixation and overall lipid/starch metabolism was observed. Overall, these results demonstrate that PGR5-deficient mutants stand as a promising source of biohydrogen when grown under conditions of sulfur deprivation. To date, photochemical characteristics of [FeFe]-hydrogenase in these mutants have yet to be investigated under conditions of sulfur deprivation.

Keywords: biofuel, biohydrogen, [FeFe]-hydrogenase, algal biofuel

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Authors: Nikoo Soleimani

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Background: Reducing torque during bone drilling is one of the effective factors in reaching to an optimal drilling process. Methods: 15 bovine femurs were drilled in vitro with a drill bit with a diameter of 4 mm using two methods of torsional ultrasonic assisted drilling (T-UAD) and convent conventional drilling (CD) and the effects of changing the feed rate and rotational speed on the torque were compared in both methods. Results: There was no significant difference in the thrust force measured in both methods due to the direction of vibrations. Results showed that using T-UAD method for bone drilling at feed rates of 0.16, 0.24 and 0.32 mm/rev led for all rotational speeds to a decrease of at least 16.3% in torque compared to the CD method. Further, using T-UAD at rotational speeds of 355~1000 rpm with various feed rates resulted in a torque reduction of 16.3~50.5% compared to CD method. Conclusions: Reducing the feed rate and increasing the rotational speed, except for the rotational speed of 500 rpm and a feed rate of 0.32 mm/rev, resulted generally in torque reduction in both methods. However, T-UAD is a more effective and desirable option for bone drilling considering its significant torque reduction.

Keywords: torsional ultrasonic assisted drilling, torque, bone drilling, rotational speed, feed rate

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Authors: Amit Keshav

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Waste bone, produced in large quantity (8-10 kg./day) from a slaughterhouse, could be a cheap (cost $0.20 per kg) substitute for commercial catalysts. In the present work, catalyst for esterification reaction was prepared from waste bone and characterized by various techniques. Bone was deoiled and then sulfonated. Fourier-transform infrared spectroscopy (FTIR) spectra of prepared catalyst predicted –OH vibration at 3416 and 1630 cm⁻¹, S-O stretching at 1124 cm⁻¹ and intense bands of hydroxypatite in a region between 500 and 700 cm⁻¹. X-ray diffraction (XRD) predicts peaks of hydroxyapatite, CaO, and tricalcium phosphate. Scanning electron microscope (SEM) was employed to reveal the presence of non-uniformity deposited fine particles on the catalyst surface that represents active acidic sites. The prepared catalyst was employed to study its performance on esterification reaction between acrylic acid and ethanol in a molar ratio of 1:1 at a set temperature of 60 °C. Results show an equilibrium conversion of 49% which is matched to the commercial catalysts employed in literature. Thus waste bone could be a good catalyst for acrylic acid removal from waste industrial streams via the process of esterification.Keywords— Heterogeneous catalyst, characterization, esterification, equilibrium conversion

Keywords: heterogeneous catalyst, characterization, esterification, equilibrium conversion

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Authors: Mei Xuan Tan, Gim-Yang Maggie Pee, Mei Chee Tan

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Academic performance, in the form of scoring high grades in enrolled subjects, is not the only significant trait in achieving success. Engineering graduates with experience in working on hands-on projects in a team setting are highly sought after in industry upon graduation. Such projects are typically real world problems that require the integration and application of knowledge and skills from several disciplines. In a traditional university setting, subjects are taught in a silo manner with no cross participation from other departments or disciplines. This may lead to knowledge compartmentalization and students are unable to understand and connect the relevance and applicability of the subject. University instructors thus see this integration across disciplines as a challenging task as they aim to better prepare students in understanding and solving problems for work or future studies. To improve students’ academic performance and to cultivate various skills such as critical thinking, there has been a gradual uptake in the use of an active learning approach in introductory science and engineering courses, where lecturing is traditionally the main mode of instruction. This study aims to discuss the implementation and experience of a hands-on, interdisciplinary project that involves all the four core subjects taught during the term at the Singapore University of Technology Design (SUTD). At SUTD, an interdisciplinary design activity, named 2D, is integrated into the curriculum to help students reinforce the concepts learnt. A student enrolled in SUTD experiences his or her first 2D in Term 1. This activity. which spans over one week in Week 10 of Term 1, highlights the application of chemistry, physics, mathematics, humanities, arts and social sciences (HASS) in designing an engineering product solution. The activity theme for Term 1 2D revolved around “work and play”. Students, in teams of 4 or 5, used a scaled-down model of a chemical launcher to launch a projectile across the room. It involved the use of a small chemical combustion reaction between ethanol (a highly volatile fuel) and oxygen. This reaction generated a sudden and large increase in gas pressure built up in a closed chamber, resulting in rapid gas expansion and ejection of the projectile out of the launcher. Students discussed and explored the meaning of play in their lives in HASS class while the engineering aspects of a combustion system to launch an object using underlying principles of energy conversion and projectile motion were revisited during the chemistry and physics classes, respectively. Numerical solutions on the distance travelled by the projectile launched by the chemical launcher, taking into account drag forces, was developed during the mathematics classes. At the end of the activity, students developed skills in report writing, data collection and analysis. Specific to this 2D activity, students gained an understanding and appreciation on the application and interdisciplinary nature of science, engineering and HASS. More importantly, students were exposed to design and problem solving, where human interaction and discussion are important yet challenging in a team setting.

Keywords: active learning, collaborative learning, first year undergraduate, interdisciplinary, STEAM

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Authors: Oum Elkhir Mahmoudi, Nebiha Ben Haj Ali

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Micropaleontological, sedimentological and statistical studies were carried out on the late Paleoceneearly Eocene succession of Sra Ouertaine and Dyr El Kef in Northern open phosphatic Basin of Tunisia. Based on the abundance and stratigraphic distribution of planktic foraminiferal species, five planktic zones have been recognized from the base to the top of the phosphatic layers. The El Acarinina sibaiyaensis Zone, the E2 Pseudohastigerina wilcoxensis Zone, the E3 Morozovella marginodentata Zone, the E4 Morozovella formosa Zones and the E5 Morozovella subbotinae Zone. The placement of Paleocene-Eocene boundary (PETM) is just below the base of the phosphatic interval. The ETM-2 event may be detectable in the analyzed biotic record of Sra Ouertaine. Based on benthic assemblages, abundances, cluster and multivariate statistical analyses, two biofacies were recognized for each section. The recognized ecozones are typical of warm and shallow water inner neritic setting (dominance of epifaunal fauna Anomalinoides, Dentalina and Cibicidoides associated with Frondicularia phosphatica, Trochamminoides globigeriniformis and Eponides elevatus). The paleoenvironment is eutrophic (presence of several bolivinitids and verneuilinids). For the Dyr El Kef section and P5 and E2 of Sra Ouertaine section, our records indicate that paleoenvironment is influenced by coastal upwelling without oxygen-deficiency, the paleodepth is estimated to be around 50 m. The paleoecosystem is diversified and balanced with a general tendency to stressed condition. While the upper part of Sra Ouertaine section is more eutrophic, influenced by coastal upwelling with oxygen-deficiency, the paleodepth is estimated to be less than 50 m and the ecosystem is unsettled.

Keywords: Tunisia, early Eocene, foraminifera, chronostratigraphy

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Authors: Siti Indati Mustapa, Hussain Ali Bekhet

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Global CO2 emission and increasing fuel consumption to meet energy demand requirement has become a threat in recent decades. Effort to reduce the CO2 emission is now a matter of priority in most countries of the world including Malaysia. Transportation has been identified as the most intensive sector of carbon-based fuels and achievement of the voluntary target to meet 40% carbon intensity reduction set at the 15th Conference of the Parties (COP15) means that the emission from the transport sector must be reduced accordingly. This posed a great challenge to Malaysia and effort has to be made to embrace suitable and appropriate energy policy for sustainable energy and emission reduction of this sector. The focus of this paper is to analyse the trends of Malaysia’s energy consumption and emission of four different transport sub-sectors (road, rail, aviation and maritime). Underlying factors influencing the growth of energy consumption and emission trends are discussed. Besides, technology status towards energy efficiency in transportation sub-sectors is presented. By reviewing the existing policies and trends of energy used, the paper highlights prospective policy options towards achieving emission reduction in the transportation sector.

Keywords: CO2 emissions, transportation sector, fuel consumption, energy policy, Malaysia

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Authors: Yoshio Kurosawa, Takao Yamaguchi

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High frequency automotive interior noise above 500 Hz considerably affects automotive passenger comfort. To reduce this noise, sound insulation material is often laminated on body panels or interior trim panels. For a more effective noise reduction, the sound reduction properties of this laminated structure need to be estimated. We have developed a new calculate tool that can roughly calculate the sound absorption and insulation properties of laminate structure and handy for designers. In this report, the outline of this tool and an analysis example applied to floor mat are introduced.

Keywords: automobile, acoustics, porous material, transfer matrix method

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Authors: Ali Gharaee, Mohammad Reza Khosravi Nikou, Bagher Anvaripour, Ali Asghar Mahjoobi

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Soil contamination by petroleum hydrocarbon (PHC) is a major concern facing the oil and gas industry. Particularly, condensate liquids have been found to contaminate soil at gas production sites. The remediation of PHCs is a difficult challenge due to the complex interaction between contaminant and soil. A study has been conducted to enhance degradation of PHCs by Fenton oxidation and using Nanoscale Zero-Valent Iron as catalyst. The various operating conditions such as initial H2O2 concentration, nZVI dosage, reaction time, and initial contamination dose were investigated. Central composite design was employed to optimize and analyze the effect of operational parameters on the PHC removal efficiency. It was found that optimal molar ratio of H2O2/Fe0 was 58 with maximum TPH removal of 84% and 3hr reaction time and initial contaminant concentration was 15g oil /kg soil. Based on the results, combination of Nanoscale ZVI and Fenton has proved to be a promising remedy for contaminated soil.

Keywords: oil contaminated Soil, fenton oxidation, zero valent iron nano-particles

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Authors: A. A. M. Azoddein, Y. Nuratri, A. B. Bustary, F. A. M. Azli, S. C. Sayuti

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Pseudomonas putida is a potential strain in biological treatment to remove mercury contained in the effluent of petrochemical industry due to its mercury reductase enzyme that able to reduce ionic mercury to elementary mercury. Freeze-dried P. putida allows easy, inexpensive shipping, handling and high stability of the product. This study was aimed to freeze dry P. putida cells with addition of lyoprotectant. Lyoprotectant was added into the cells suspension prior to freezing. Dried P. putida obtained was then mixed with synthetic mercury. Viability of recovery P. putida after freeze dry was significantly influenced by the type of lyoprotectant. Among the lyoprotectants, tween 80/ sucrose was found to be the best lyoprotectant. Sucrose able to recover more than 78% (6.2E+09 CFU/ml) of the original cells (7.90E+09CFU/ml) after freeze dry and able to retain 5.40E+05 viable cells after 4 weeks storage in 4oC without vacuum. Polyethylene glycol (PEG) pre-treated freeze dry cells and broth pre-treated freeze dry cells after freeze-dry recovered more than 64% (5.0 E+09CFU/ml) and >0.1% (5.60E+07CFU/ml). Freeze-dried P. putida cells in PEG and broth cannot survive after 4 weeks storage. Freeze dry also does not really change the pattern of growth P. putida but extension of lag time was found 1 hour after 3 weeks of storage. Additional time was required for freeze-dried P. putida cells to recover before introduce freeze-dried cells to more complicated condition such as mercury solution. The maximum mercury reduction of PEG pre-treated freeze-dried cells after freeze dry and after storage 3 weeks was 56.78% and 17.91%. The maximum of mercury reduction of tween 80/sucrose pre-treated freeze-dried cells after freeze dry and after storage 3 weeks were 26.35% and 25.03%. Freeze dried P. putida was found to have lower mercury reduction compare to the fresh P. putida that has been growth in agar. Result from this study may be beneficial and useful as initial reference before commercialize freeze-dried P. putida.

Keywords: Pseudomonas putida, freeze-dry, PEG, tween80/Sucrose, mercury, cell viability

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Authors: Khamael M. Abualnaja, Lidija Šiller, Ben R. Horrocks

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Metal enhanced luminescence of alkyl-capped silicon quantum dots (C11-SiQDs) was obtained by mixing C11-SiQDs with silver nanoparticles (AgNPs). C11-SiQDs have been synthesized by galvanostatic method of p-Si (100) wafers followed by a thermal hydrosilation reaction of 1-undecene in refluxing toluene in order to extract alkyl-capped silicon quantum dots from porous Si. The chemical characterization of C11-SiQDs was carried out using X-ray photoemission spectroscopy (XPS). C11-SiQDs have a crystalline structure with a diameter of 5 nm. Silver nanoparticles (AgNPs) of two different sizes were synthesized also using photochemical reduction of silver nitrate with sodium dodecyl sulphate. The synthesized Ag nanoparticles have a polycrystalline structure with an average particle diameter of 100 nm and 30 nm, respectively. A significant enhancement up to 10 and 4 times in the luminescence intensities was observed for AgNPs100/C11-SiQDs and AgNPs30/C11-SiQDs mixtures, respectively using 488 nm as an excitation source. The enhancement in luminescence intensities occurs as a result of the coupling between the excitation laser light and the plasmon bands of Ag nanoparticles; thus this intense field at Ag nanoparticles surface couples strongly to C11-SiQDs. The results suggest that the larger Ag nanoparticles i.e.100 nm caused an optimum enhancement in the luminescence intensity of C11-SiQDs which reflect the strong interaction between the localized surface plasmon resonance of AgNPs and the electric field forming a strong polarization near C11-SiQDs.

Keywords: silicon quantum dots, silver nanoparticles (AgNPs), luminescence, plasmon

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Authors: Abimbola M. Enitan, Josiah Adeyemo, Sheena Kumari, Feroz M. Swalaha, Faizal Bux

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With the competing demand on water resources and water reuse, discharge of industrial effluents into the aquatic environment has become an important issue. Much attention has been placed on the impact of industrial wastewater on water bodies worldwide due to the accumulation of organic and inorganic matter in the receiving water bodies. The scope of the present work is to assess the physic-chemical composition of the wastewater produced from one of the brewery industry in South Africa. This is to estimate the environmental impact of its discharge into the receiving water bodies or the municipal treatment plant. The parameters monitored for the quantitative analysis of brewery wastewater include biological oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids, volatile suspended solids, ammonia, total oxidized nitrogen, nitrate, nitrite, phosphorus, and alkalinity content. In average, the COD concentration of the brewery effluent was 5340.97 mg/l with average pH values of 4.0 to 6.7. The BOD and the solids content of the wastewater from the brewery industry were high. This means that the effluent is very rich in organic content and its discharge into the water bodies or the municipal treatment plant could cause environmental pollution or damage the treatment plant. In addition, there were variations in the wastewater composition throughout the monitoring period. This might be as a result of different activities that take place during the production process, as well as the effects of the peak period of beer production on the water usage.

Keywords: Brewery wastewater, environmental pollution, industrial effluents, physic-chemical composition

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Authors: Somit Dutta, Pallab Kar, Arnab Kumar Chakraborty, Arnab Sen, Tapas Kumar Chaudhuri

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In the present study three species of Clerodendrum; Clerodendrum indicum, Volkameria inermis and Clerodendrum colebrookianum were used to investigate the possible activity against oxidative stress. A detailed in-vivo and in-vitro antioxidant profiling, directly associated with inflammation-related carcinogenesis, has been executed with a motive to evaluate the free radical scavenging activity of Clerodendrum extract. Measurement of cell viability and ROS generation in HEK-293 (Human Embryonic Kidney Cell Line) cells was also estimated. The immune cell proliferative properties (MTT) and in-vitro assay for evaluation of their antioxidant activities including hydroxyl radical, nitric oxide, singlet oxygen, peroxinitrate and hydrogen peroxide, etc. were investigated. GC-MS and FTIR analyses have been performed to identify the active biological compounds. These active biological compounds were further studied to assess their potential medicinal properties, aided by molecular docking and interaction analysis between the active compounds and different proteins related to oxidative stress leading to progression of carcinogenesis. The research article clearly demonstrates the role of ROS in various phases of carcinogenesis. Therefore, the antioxidant and free radical scavenging capacity of all the Clerodendrum species might prove beneficial for the immune system. It might be concluded that this plant species offers great promise for cancer prevention and therapy due to the presence of several bioactive compounds and potent antioxidant capacity of C. colebrookianum.

Keywords: antioxidant, cancer, oxidative stress, reactive oxygen species (ROS)

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Authors: Vallejo Michael, Acuña Edgar, Roa Juan David, Peñuela Rosa, Parra Alejandra, Casallas Daniela, Rodriguez Sheyla

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Congenital Zika Virus Syndrome is an entity composed by a variety of birth defects presented in newborns that have been exposed to the Zika Virus during pregnancy. The syndrome characteristic features are severe microcephaly, cerebral tissue abnormalities, ophthalmological abnormalities such as uveitis and chorioretinitis, arthrogryposis, clubfoot deformity and muscular tone abnormalities. The confirmatory test is the Reverse transcription polymerase chain reaction (RT-PCR) associated to the physical findings. Here we present the case of a newborn with microcephaly whose mother presented a confirmed Zika Virus infection during the third trimester of pregnancy, despite of the evident findings and the history of Zika infection the RT-PCR in amniotic and cerebrospinal fluid of the newborn was negative. RT-PCR has demonstrated a low sensibility in samples with low viral loads, reason why, we propose a clinical diagnosis in patients with clinical history of Zika Virus infection during pregnancy accompanied by evident clinical manifestations of the child.

Keywords: congenital, Zika virus, microcephaly, reverse transcriptase polymerase chain reaction

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Authors: Veronica Caprai, Katrin Schollbach, Miruna V. A. Florea, H. J. H. Brouwers

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Nowadays MSWI (Municipal Solid Waste Incineration) bottom ash (BA) produced by Waste-to-Energy (WtE) plants represents the majority of the solid residues derived from MSW incineration. Once processed, the BA is often landfilled resulting in possible environmental problems, additional costs for the plant and increasing occupation of public land. In order to limit this phenomenon, European countries such as the Netherlands aid the utilization of MSWI BA in the construction field, by providing standards about the leaching of contaminants into the environment (Dutch Soil Quality Decree). Commonly, BA has a particle size below 32 mm and a heterogeneous chemical composition, depending on its source. By washing coarser BA, an MSWI sludge is obtained. It is characterized by a high content of heavy metals, chlorides, and sulfates as well as a reduced particle size (below 0.25 mm). To lower its environmental impact, MSWI sludge is filtered or centrifuged for removing easily soluble contaminants, such as chlorides. However, the presence of heavy metals is not easily reduced, compromising its possible application. For lowering the leaching of those contaminants, the use of MSWI residues in combination with cement represents a precious option, due to the known retention of those ions into the hydrated cement matrix. Among the applications, the European standard for common cement EN 197-1:1992 allows the incorporation of up to 5% by mass of a minor additional constituent (MAC), such as fly ash or blast furnace slag but also an unspecified filler into cement. To the best of the author's knowledge, although it is widely available, it has the appropriate particle size and a chemical composition similar to cement, FC has not been investigated as possible MAC in cement production. Therefore, this paper will address the suitability of MSWI FC as MAC for CEM I 52.5 R, within a 5% maximum replacement by mass. After physical and chemical characterization of the raw materials, the crystal phases of the pastes are determined by XRD for 3 replacement levels (1%, 3%, and 5%) at different ages. Thereafter, the impact of FC on mechanical and environmental performances of cement is assessed according to EN 196-1 and the Dutch Soil Quality Decree, respectively. The investigation of the reaction products evidences the formation of layered double hydroxides (LDH), in the early stage of the reaction. Mechanically the presence of FC results in a reduction of 28 days compressive strength by 8% for a replacement of 5% wt., compared with the pure CEM I 52.5 R without any MAC. In contrast, the flexural strength is not affected by the presence of FC. Environmentally, the Dutch legislation for the leaching of contaminants for unshaped (granular) material is satisfied. Based on the collected results, FC represents a suitable candidate as MAC in cement production.

Keywords: environmental impact evaluation, Minor additional constituent, MSWI residues, X-ray diffraction crystallography

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Authors: Wahyu Eko Diyanto, Amalia Dyah Arumsari, Ulfatu Layinatinnahdiyah Arrosyadi

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Tofu industry is one of the local food industry which is can being competitive industry in the ASEAN Economic Community (AEC). However, a lot of tofu entrepreneurs just thinking how to produce good quality product without considering the impact of environmental conditions from the production process. Production of tofu per day requires a number of 15 kg with liquid waste generated is 652.5 liters. That liquid waste is discharged directly into waterways, whereas tofu liquid waste contains organic compounds that quickly unraveled, so it can pollute waterways. In addition, tofu liquid waste is high in Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), nitrogen and phosphorus. This research is aim to create a method of handling liquid waste effectively and efficiently by using water lettuce. The method is done by observation and experiment by using phytoremediation method in the tofu liquid waste using water lettuce and adding aeration to reduce the concentration of contaminants. The results of the research analyzed the waste quality standard parameters based on SNI (National Standardization Agency of Indonesia). The efficiency concentration and parameters average of tofu liquid waste are obtained pH 3,42% (from 4,0 to be 3,3), COD 76,13% (from 3579 ppm to be 854 ppm), BOD 55 % (from 11600 ppm to be 5242 ppm), TSS 93,6% (from 3174 ppm to be 203 ppm), turbidity is 64,8% (from 977 NTU to be 1013 NTU), and temperature 36oC (from 45oC to be 40oC). The efficiency of these parameters indicates a safe value for the effluent to be channeled in waterways. Water lettuce and tofu liquid waste phytoremediation result will be used as biogas as renewable energy.

Keywords: aeration, phytoremediation, water letuce, tofu liquid waste

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Authors: Hamad R. Jappor, Zeyad Adnan Saleh, Mudar A. Abdulsattar

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The ab initio restricted Hartree-Fock method is used to simulate the electronic structure of indium phosphide (InP) nanocrystals (NCs) (216-738 atoms) with sizes ranging up to about 2.5 nm in diameter. The calculations are divided into two parts, surface, and core. The oxygenated (001)-(1×1) facet that expands with larger sizes of nanocrystals is investigated to determine the rule of the surface in nanocrystals electronic structure. Results show that lattice constant and ionicity of the core part show decreasing order as nanocrystals grow up in size. The smallest investigated nanocrystal is 1.6% larger in lattice constant and 131.05% larger in ionicity than the converged value of largest investigated nanocrystal. Increasing nanocrystals size also resulted in an increase of core cohesive energy (absolute value), increase of core energy gap, and increase of core valence. The surface states are found mostly non-degenerated because of the effect of surface discontinuity and oxygen atoms. Valence bandwidth is wider on the surface due to splitting and oxygen atoms. The method also shows fluctuations in the converged energy gap, valence bandwidth and cohesive energy of core part of nanocrystals duo to shape variation. The present work suggests the addition of ionicity and lattice constant to the quantities that are affected by quantum confinement phenomenon. The method of the present model has threefold results; it can be used to approach the electronic structure of crystals bulk, surface, and nanocrystals.

Keywords: InP, nanocrystals core, ionicity, Hartree-Fock method, large unit cell

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Authors: John Okanda Okwaro

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Carbon (IV) oxide (CO₂) is emitted majorly from fossil fuel combustion and industrial production. The sources of interest of carbon (IV) oxide in the study area are mining activities, transport systems, and industrial processes. This study is aimed at building models that will help in monitoring the emissions within the study area. Three scenarios were discussed, namely: pessimistic scenario, business-as-usual scenario, and optimistic scenario. The result showed that there was a reduction in carbon dioxide concentration by approximately 50.5 ppm between March 2020 and January 2021 inclusive. This is majorly due to reduced human activities that led to decreased consumption of energy. Also, the CO₂ concentration trend follows the business-as-usual scenario (BAU) path. From the models, the pessimistic, business-as-usual, and optimistic scenarios give CO₂ concentration of about 545.9 ppm, 408.1 ppm, and 360.1 ppm, respectively, on December 31st, 2021. This research helps paint the picture to the policymakers of the relationship between energy sources and CO₂ emissions. Since the reduction in CO₂ emission was due to decreased use of fossil fuel as there was a decrease in economic activities, then if Kenya relies more on green energy than fossil fuel in the post-COVID-19 period, there will be more CO₂ emission reduction. That is, the CO₂ concentration trend is likely to follow the optimistic scenario path, hence a reduction in CO₂ concentration of about 48 ppm by the end of the year 2021. This research recommends investment in solar energy by energy-intensive companies, mine machinery and equipment maintenance, investment in electric vehicles, and doubling tree planting efforts to achieve the 10% cover.

Keywords: forecasting, greenhouse gas, green energy, hierarchical data format

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Authors: Jenaidullah Batur, Sebghatullah Mudaber

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Currently, there is a list of catalysts that can reduce CO₂ to valuable chemicals and fuels, among them metal oxides such as TiO₂, known as promising photocatalysts to produce hydrogen and CO unless they are at an earlier age and still need to promote activity to able for produce fabricated values. Herein, in this work, we provided a novel, facile and eco-friendly synthesis strategy to synthesize more effective TiO₂-organic composite materials to selectively reduce CO₂ to CO. In this experiment, commercial nanocrystalline TiO₂ and saccharin with Li (LiBr, LiCl) were synthesized using the facile physical grinding in the motel pestle for 10 minutes, then added 10 mL of deionized water (18.2 megaohms) on the 300mg composite catalyst before samples moving for hydrothermal heating for 24 hours at 80 C in the oven. Compared with nanosized TiO₂, the new TiO₂-Sac-Li indeed displays a high CO generation rate of 70.83 μmol/g/h, which is 7 times higher than TiO₂, which shows enhancement in CO₂ reduction and an apparent improvement in charge carrier dynamic. The CO₂ reduction process at the gas-solid interface on TiO₂-Sac-Li composite semiconductors is investigated by functional calculations and several characterization methods. The results indicate that CO₂ can be easily activated by the TiO₂-Sac-Li atoms on the surface. This work innovatively investigates CO₂ reduction in novel composite materials and helps to broaden the applications of composite materials semiconductors.

Keywords: green chemistry, green synthesis, TiO₂, photocatalyst

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Authors: Lubica Muckova, Petr Jost, Jaroslav Pejchal, Daniel Jun

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The development of acetylcholinesterase reactivators, i.e. antidotes against organophosphorus poisoning, is an important goal of defence research. The aim of this study was to compare cytotoxicity and chemical structure of 5 currently available (pralidoxime, trimedoxime, obidoxime, methoxime, and asoxime) and 4 newly developed compounds (K027, K074, K075, and K203). In oximes, there could be at least four important structural factors affecting their toxicity, including the number of oxime groups in the molecule, the position of oxime group(s) on pyridinium ring, the length of carbon linker, and the substitution by oxygen or insertion of the double bond into the connection chain. The cytotoxicity of tested substances was measured using colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay (MTT assay) in SH-SY5Y cell line. Toxicity was expressed as toxicological index IC₅₀. The tested compounds showed different cytotoxicity ranging from 1.5 to 27 mM. K027 was the least, and methoxime was the most toxic reactivator. The lowest toxicity was found in a monopyridinium reactivator and bispyridinium reactivators with simple 3C carbon linker. Shortening of connection chain length to 1C, incorporation of oxygen moiety into 3C compounds, elongation of carbon linker to 4C and insertion of a double bond into 4C substances increase AChE reactivators' cytotoxicity. Acknowledgements: This work was supported by a long-term organization development plan Medical Aspects of Weapons of Mass Destruction of the Faculty of Military Health Sciences, University of Defence.

Keywords: acetylcholinesterase, cytotoxicity, organophosphorus poisoning, reactivators of acetylcholinesterase

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Authors: Bismina Akbar, Smitha M. V.

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Flooding is a global phenomenon that causes widespread devastation, economic damage, and loss of human lives. In the past twenty years, the number of reported flood events has increased significantly. Millions of people around the globe are at risk of flooding from coastal, dam breaks, groundwater, and urban surface water and wastewater sources. Climate change is one of the important causes for them since it affects, directly and indirectly, the river network. Although the contribution of climate change is undeniable, human contributions are there to increase the frequency of floods. There are different types of floods, such as Flash floods, Coastal floods, Urban floods, River (or fluvial) floods, and Ponding (or pluvial flooding). This study focuses on formulating mitigation strategies for urban flood risk reduction through analysis of different best practice case studies, including China, Japan, Indonesia, and Brazil. The mitigation measures suggest that apart from the structural and non-structural measures, environmental considerations like blue-green solutions are beneficial for flood risk reduction. And also, Risk-Informed Master plans are essential nowadays to take risk-based decision processes that enable more sustainability and resilience.

Keywords: hazard, mitigation, risk reduction, urban flood

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Authors: Sweta Iyer, Nemeshwaree Behary, Jinping Guan, Guoqiang Chen, Vincent Nierstrasz

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Flavin mononucleotide widely known as 'FMN' is a biobased resource derived from riboflavin. The isoalloxazine ring present in the FMN molecule attributes the photoluminescence phenomenon, whereas FMN molecule in the presence of bacterial luciferase enzyme and co-factors such as NADH, long chain aldehyde leads to bioluminescence reaction. In this study, the FMN molecule was treated on cellulosic textile using chromojet technique and the photoluminescence property was characterized using spectroscopy technique. Further, the FMN was used as a substrate along with enzymes and co-factors to treat the non-woven textile, and the bioluminescence property was explored using luminometer equipment. The investigation revealed photoluminescence property on cellulosic textile, and the emission peak was observed at a wavelength around 530 nm with an average corrected spectral intensity of 10×106 CPS/Microamps. In addition, the measurement of nonwoven textile using bioluminescence reaction system exhibited light intensity measured in the form of relative light units (RLU). The study enabled to explore the use of FMN as both photoluminescent and bioluminescent textile. Further investigation would require for stability study of the same to provide an eco-efficient approach to obtain luminescent textile.

Keywords: flavin mononucleotide, photoluminescence, bioluminescence, luminescent textile

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Authors: Seung Ju Yeon, Seul Ki Min, Jun Sang Park, Yeo Seon Kwon, Hoo Cheol Lee, Hyun Jung Shim, Il-Doo Kim, Ja Kyeong Lee, Hwa Sung Shin

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In brain injury, depleting oxidative stress is the most effective way to reduce the brain infarct size. C-phycocyanin (C-Pc) is a well-known antioxidant protein that has neuroprotective effects obtained from green microalgae. Astrocyte is glial cell that supports the nerve cell such as neuron, which account for a large portion of the brain. In brain injury, such as ischemia and reperfusion, astrocyte has an important rule that overcomes the oxidative stress and protect from brain reactive oxygen species (ROS) injury. However little is known about how C-Pc regulates the anti-oxidants effects of astrocyte. In this study, when the C-Pc was treated in oxidized astrocyte, we confirmed that inflammatory factors Interleukin-6 and Interleukin-3 were increased and antioxidants enzyme, Superoxide dismutase (SOD) and catalase was upregulated, and neurotrophic factors, brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) was alleviated. Also, it was confirmed to reduce infarct size of the brain in ischemia and reperfusion because C-Pc has anti-oxidant effects in middle cerebral artery occlusion (MCAO) animal model. These results show that C-Pc can help astrocytes lead neuroprotective activities in the oxidative stressed environment of the brain. In summary, the C-PC protects astrocytes from oxidative stress and has anti-oxidative, anti-inflammatory, neurotrophic effects under ischemic situations.

Keywords: c-phycocyanin, astrocyte, reactive oxygen species, ischemia and reperfusion, neuroprotective effect

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Authors: W. Jahouach-Rabai, J. Aribi, Z. Azzouz-Berriche, R. Lahsni, F. Hosni

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Gamma irradiation applied in removing pharmaceutical contaminants from wastewater is an effective advanced oxidation process (AOP), considered as an alternative to conventional water treatment technologies. In this purpose, the degradation efficiency of several detected contaminants under gamma irradiation was evaluated. In fact, radiolysis of organic pollutants in aqueous solutions produces powerful reactive species, essentially hydroxyl radical ( ·OH), able to destroy recalcitrant pollutants in water. Pharmaceuticals considered in this study are aqueous solutions of paracetamol, ibuprofen, and diclofenac at different concentrations 0.1-1 mmol/L, which were treated with irradiation doses from 3 to 15 kGy. The catalytic oxidation of these compounds by gamma irradiation was investigated using hydrogen peroxide (H₂O₂) as a convenient oxidant. Optimization of the main parameters influencing irradiation process, namely irradiation doses, initial concentration and oxidant volume (H₂O₂) were investigated, in the aim to release high degradation efficiency of considered pharmaceuticals. Significant modifications attributed to these parameters appeared in the variation of degradation efficiency, chemical oxygen demand removal (COD) and concentration of radio-induced radicals, confirming them synergistic effect to attempt total mineralization. Pseudo-first-order reaction kinetics could be used to depict the degradation process of these compounds. A sophisticated analytical study was released to quantify the detected radio-induced radicals (electron paramagnetic resonance spectroscopy (EPR) and high performance liquid chromatography (HPLC)). All results showed that this process is effective for the degradation of many pharmaceutical products in aqueous solutions due to strong oxidative properties of generated radicals mainly hydroxyl radical. Furthermore, the addition of an optimal amount of H₂O₂ was efficient to improve the oxidative degradation and contribute to the high performance of this process at very low doses (0.5 and 1 kGy).

Keywords: AOP, COD, hydroxyl radical, EPR, gamma irradiation, HPLC, pharmaceuticals

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Authors: Muthana A. M. Jamel Al-Gburi

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Elimination of carbon dioxide (CO2) gas from our atmosphere is very important but complicated, and since there is always an increase in the gas amounts of the other greenhouse ones in our atmosphere, causes by both some of the human activities and the burning of the fossil fuels, which leads to the Global Warming phenomena i.e., increasing the earth temperature to a higher level, creates desertification, tornadoes and storms. In our present research project, we constructed our own system to extract carbon dioxide directly from the atmospheric air at the room conditions and investigated how to convert the gas into a useful mineral or Nano scale fibers made of carbon by using several chemical processes and chemical reactions leading to a valuable building material and also to mitigate the environmental negative change. In the present water pool system (Carbone Dioxide Domestic Extractor), the ocean-sea water was used to dissolve the CO2 gas from the room and converted into carbonate minerals by using a number of additives like shampoo, clay and MgO. Note that the atmospheric air includes CO2 gas has circulated within the sea water by air pump connected to a perforated tubes fixed deep on the pool base. Those chemical agents were mixed with the ocean-sea water to convert the formed acid from the water-CO2 reaction into a useful mineral. After we successfully constructed the system, we did intense experiments and investigations on the CO2 gas reduction level and found which is the optimum active chemical agent to work in the atmospheric conditions.

Keywords: global warming, CO₂ gas, ocean-sea water, additives, solubility level

Procedia PDF Downloads 87

Authors: Radek Novotny, Michal Novak, Daniela Marusakova, Monika Sipova, Hugo Fuentes, Peter Borst

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This research has been conducted within the European HORIZON 2020 project ECC-SMART. The main objective is to assess whether it is feasible to design and develop a small modular reactor (SMR) that would be cooled by supercritical water (SCW). One of the main objectives for material research concerns the corrosion of the candidate cladding materials. The experimental part has been conducted in support of the qualification procedure of the future SCW-SMR constructional materials. The last objective was to identify the gaps in current norms and guidelines. Apart from corrosion, resistance testing of candidate materials stresses corrosion cracking susceptibility tests have been performed in supercritical water. This paper describes part of these tests, in particular, those slow strain rate tensile loading applied for tangential ring shape specimens of two candidate materials, Alloy 800H and 310S stainless steel. These ring tensile tests are one the methods used for tensile testing of nuclear cladding. Here full circular heads with dimensions roughly equal to the inner diameter of the sample and the gage sections are placed in the parallel direction to the applied load. Slow strain rate tensile tests have been conducted in 380 or 500oC supercritical water applying two different elongation rates, 1x10-6 and 1x10-7 s-1. The effect of temperature and dissolved oxygen content on the SCC susceptibility of Alloy 800H and 310S stainless steel was investigated when two different temperatures and concentrations of dissolved oxygen were applied in supercritical water. The post-fracture analysis includes fractographic analysis of the fracture surfaces using SEM as well as cross-sectional analysis on the occurrence of secondary cracks. Assessment of the effect of environment and dissolved oxygen content was by comparing to the results of the reference tests performed in air and N2 gas overpressure. The effect of high temperature on creep and its role in the initiation of SCC was assessed as well. It has been concluded that the applied test method could be very useful for the investigation of stress corrosion cracking susceptibility of candidate cladding materials in supercritical water.

Keywords: stress corrosion cracking, ring tensile tests, super-critical water, alloy 800H, 310S stainless steel

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Authors: Vinu Viswanath, Lawrence Dsouza, Ugo Ravon

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Syngas typically and intermediary gas product has a wide range of application of producing various chemical products, such as mixed alcohols, hydrogen, ammonia, Fischer-Tropsch products methanol, ethanol, aldehydes, alcohols, etc. There are several technologies available for the syngas production. An alternative to the conventional processes an attractive route of utilizing carbon dioxide and methane in equimolar ratio to generate syngas of ratio close to one has been developed which is also termed as Dry Reforming of Methane technology. It also gives the privilege to utilize the greenhouse gases like CO2 and CH4. The dry reforming process is highly endothermic, and indeed, ΔG becomes negative if the temperature is higher than 900K and practically, the reaction occurs at 1000-1100K. At this temperature, the sintering of the metal particle is happening that deactivate the catalyst. However, by using this strategy, the methane is just partially oxidized, and some cokes deposition occurs that causing the catalyst deactivation. The current research work was focused to mitigate the main challenges of dry reforming process such coke deposition, and metal sintering at high temperature.To achieve these objectives, we employed three different strategies of catalyst development. 1) Use of bulk catalysts such as olivine and pyrochlore type materials. 2) Use of metal doped support materials, like spinel and clay type material. 3) Use of core-shell model catalyst. In this approach, a thin layer (shell) of redox metal oxide is deposited over the MgAl2O4 /Al2O3 based support material (core). For the core-shell approach, an active metal is been deposited on the surface of the shell. The shell structure formed is a doped metal oxide that can undergo reduction and oxidation reactions (redox), and the core is an alkaline earth aluminate having a high affinity towards carbon dioxide. In the case of metal-doped support catalyst, the enhanced redox properties of doped CeO2 oxide and CO2 affinity property of alkaline earth aluminates collectively helps to overcome coke formation. For all of the mentioned three strategies, a systematic screening of the metals is carried out to optimize the efficiency of the catalyst. To evaluate the performance of them, the activity and stability test were carried out under reaction conditions of temperature ranging from 650 to 850 ̊C and an operating pressure ranging from 1 to 20 bar. The result generated infers that the core-shell model catalyst showed high activity and better stable DR catalysts under atmospheric as well as high-pressure conditions. In this presentation, we will show the results related to the strategy.

Keywords: carbon dioxide, dry reforming, supports, core shell catalyst

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Authors: Sanja Manchevska, Vaska Antevska, Lidija Todorovska, Beti Dejanova, Sunchica Petrovska, Ivanka Karagjozova, Elizabeta Sivevska, Jasmina Pluncevic Gligoroska

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Introduction: A number of positive effects on the player’s physical status, including the body mass components are attributed to training process. As young soccer players grow up qualitative and quantitative changes appear and contribute to better performance. Player’s anthropometric and physiologic characteristics are recognized as important determinants of performance. Material: A sample of 52 soccer players with an age span from 9 to 14 years were divided in two groups differentiated by age. The younger group consisted of 25 boys under 11 years (mean age 10.2) and second group consisted of 27 boys with mean age 12.64. Method: The set of basic anthropometric parameters was analyzed: height, weight, BMI (Body Mass Index) and body mass components. Maximal oxygen uptake was tested using the treadmill protocol by Brus. Results: The group aged under 11 years showed the following anthropometric and physiological features: average height= 143.39cm, average weight= 44.27 kg; BMI= 18.77; Err = 5.04; Hb= 13.78 g/l; VO2=37.72 mlO2/kg. Average values of analyzed parameters were as follows: height was 163.7 cm; weight= 56.3 kg; BMI = 19.6; VO2= 39.52 ml/kg; Err=5.01; Hb=14.3g/l for the participants aged 12 to14 years. Conclusion: Physiological parameters (maximal oxygen uptake, erythrocytes and Hb) were insignificantly higher in the older group compared to the younger group. There were no statistically significant differences between analyzed anthropometric parameters among the two groups except for the basic measurements (height and weight).

Keywords: body composition, young soccer players, BMI, physical status

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Authors: O. Afshar

Abstract:

A solar receiver is designed for operation under extremely uneven heat flux distribution, cyclic weather, and cloud transient cycle conditions, which can include large thermal stress and even receiver failure. In this study, the effect of different oil velocity on convection coefficient factor and impact of wind velocity on local Nusselt number by Finite Volume Method will be analyzed. This study is organized to give an overview of the numerical modeling using a MATLAB software, as an accurate, time efficient and economical way of analyzing the heat transfer trends over stationary receiver tube for different Reynolds number. The results reveal when oil velocity is below 0.33m/s, the value of convection coefficient is negligible at low temperature. The numerical graphs indicate that when oil velocity increases up to 1.2 m/s, heat convection coefficient increases significantly. In fact, a reduction in oil velocity causes a reduction in heat conduction through the glass envelope. In addition, the different local Nusselt number is reduced when the wind blows toward the concave side of the collector and it has a significant effect on heat losses reduction through the glass envelope.

Keywords: receiver tube, heat convection, heat conduction, Nusselt number

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Authors: Kyou Hee Shim, Hwa Sung Shin

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When a thrombolysis agent is administered to treat ischemic stroke, excessive reactive oxygen species are generated due to a sudden provision of oxygen and occurs secondary damage cell necrosis. Thus, it is necessary to administrate adjuvant as well as thrombolysis agent to protect and reduce damaged tissue. As cerebral blood vessels have specific structure called blood-brain barrier (BBB), it is not easy to transfer substances from blood to tissue. Therefore, development of a drug carrier is required to increase drug delivery efficiency to brain tissue. In this study, cyanobacterial pigment from the blue-green algae known for having neuroprotective effect as well as antioxidant effect was nasally administrated for bypassing BBB. In order to deliver cyanobacterial pigment efficiently, the nano-sized liposome was used as a carrier. Liposomes were coated with a positive charge of chitosan since negative residues are present at the nasal mucosa the first gateway of nasal administration. Characteristics of liposome including morphology, size and zeta potential were analyzed by transmission electron microscope (TEM) and zeta analyzer. As a result of cytotoxic test, the liposomes were not harmful. Also, being administered a drug to the ischemic stroke animal model, we could confirm that the pharmacological effect of the pigment delivered by chitosan coated liposome was enhanced compared to that of non-coated liposome. Consequently, chitosan coated liposome could be considered as an optimized drug delivery system for the treatment of acute ischemic stroke.

Keywords: ischemic stroke, cyanobacterial pigment, liposome, chitosan, nasal administration

Procedia PDF Downloads 227