Search results for: short-term toxicity test

Authors: Jung-Il Suh, Hong-Gun Park, Jae-Eun Oh

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Recently, the use of long-span precast concrete (PC) construction has increased in modular construction such as storage buildings and parking facilities. When applying long span PC member, reducing weight of long span PC member should be conducted considering lifting capacity of crane and self-weight of PC member and use of structural lightweight concrete made by lightweight aggregate (LWA) can be considered. In the process of lightweight concrete production, segregation and bleeding could occur due to difference of specific gravity between cement (3.3) and lightweight aggregate (1.2~1.8) and reducing weight of binder is needed to prevent the segregation between binder and aggregate. Also, lightweight precast concrete made by cementitious materials such as fly ash and ground granulated blast furnace (GGBFS) which is lower than specific gravity of cement as a substitute for cement has been studied. When only using fly ash for cementless binder alkali-activation of fly ash is most important chemical process in which the original fly ash is dissolved by a strong alkaline medium in steam curing with high-temperature condition. Because curing condition is similar with environment of precast member production, additional process is not needed. Na-based chloride generally used as a strong alkali activator has a practical problem such as high pH toxicity and high manufacturing cost. Instead of Na-based alkali activator calcium hydroxide [Ca(OH)2] and sodium hydroxide [Na2CO3] might be used because it has a lower pH and less expensive than Na-based alkali activator. This study explored the influences on Ca(OH)2-Na2CO3-activated fly ash system in its microstructural aspects and strength and permeability using powder X-ray analysis (XRD), thermogravimetry (TGA), mercury intrusion porosimetry (MIP). On the basis of microstructural analysis, the conclusions are made as follows. Increase of Ca(OH)2/FA wt.% did not affect improvement of compressive strength. Also, Ca(OH)2/FA wt.% and Na2CO3/FA wt.% had little effect on specific gravity of saturated surface dry (SSD) and absolute dry (AD) condition to calculate water absorption. Especially, the binder is appropriate for structural lightweight concrete because specific gravity of the hardened paste has no difference with that of lightweight aggregate. The XRD and TGA/DTG results did not present considerable difference for the types and quantities of hydration products depending on w/b ratio, Ca(OH)2 wt.%, and Na2CO3 wt.%. In the case of higher molar quantity of Ca(OH)2 to Na2CO3, XRD peak indicated unreacted Ca(OH)2 while DTG peak was not presented because of small quantity. Thus, presence of unreacted Ca(OH)2 is too small quantity to effect on mechanical performance. As a result of MIP, the porosity volume related to capillary pore depends on the w/b ratio. In the same condition of w/b ratio, quantities of Ca(OH)2 and Na2CO3 have more influence on pore size distribution rather than total porosity. While average pore size decreased as Na2CO3/FA w.t% increased, the average pore size increased over 20 nm as Ca(OH)2/FA wt.% increased which has inverse proportional relationship between pore size and mechanical properties such as compressive strength and water permeability.

Keywords: Ca(OH)2, compressive strength, microstructure, fly ash, Na2CO3, water absorption

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Authors: Andrei Shishkin, Aleksandrs Korjakins, Viktors Mironovs

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Present paper describes method of obtaining clay ceramic foam (CCF) and foam concrete (FC), by direct foaming with high speed mixer-disperser (HSMD). Three foaming agents (FA) are compared for the FC and CCF production: SCHÄUMUNGSMITTEL W 53 FLÜSSIG (Zschimmer & Schwarz Gmbh, Germany), SCF-1245 (Sika, test sample, Latvia) and FAB-12 (Elade, Latvija). CCF were obtained at 950, 1000°C, 1150°C and 1150°C firing temperature and have mechanical compressive strength 1.2, 2.55, and 4.3 MPa and porosity 79.4, 75.1, 71.6%, respectively. Obtained FC has 6-14 MPa compressive strength and porosity 44-55%. The goal of this work was the development of a sustainable and durable ceramic cellular structures using HSMD.

Keywords: ceramic foam, foam concrete, clay foam, open cell, close cell, direct foaming

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Authors: Petra F. A. Dilling, Sinan Caykoylu

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The aim of this study was to shed light on the understanding of the factors determining a company’s disclosure on climate change reporting. The underlying study examines the effect of gender diversity and the mediating effect of female representation in management and on the board of directors and the existence of a dedicated sustainability board committee. To test the study’s objectives, the authors use a global sample of the largest companies and their reporting for the year 2020. The results suggest that corporate female participation has a significant influence on the quality of climate change reporting. In addition, having a dedicated sustainability board committee also significantly impacts the non-financial disclosure of climate change information.

Keywords: climate change, non-financial reporting, governance, board diversity, sustainability, CSR

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Authors: Marta Chiapasco, Alexandra Porter, Finn Giuliani

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Designing polymers with a specific microstructure can affect how the polymer degrades once released in the environment. Not only the amount but also the distribution of different phases determines a polymers’ degradability. The following research investigates the use of a combination of spectroscopy analysis and thermal analysis to study changes of polymers’ amorphous and crystalline phases during degradation, comparing different microstructures of polypropylene and polyethylene. The use of nanoindentation helps study how degradation proceeds across a material by looking at changes in phases, while bulk tensile test describes when the material fails. The first results demonstrate that different microstructures have different degrading rates, with homopolymer having a linear and faster degradation compared to copolymers. The goal is to create materials that degrade at faster rates without releasing microplastics into the environment.

Keywords: degradation, microstructure, nanoindentation, Raman spectroscopy

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Authors: Sania Ashraf

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The paper focuses on the prevalence of informational efficiency and integration of GCC Shariah Equity market for the period of 01st January 2010 to 31st June 2015 with daily equity returns of Kuwait, Oman, Qatar, Bahrain, Saudi Arabia and United Arab Emirates. The study employs traditional as well as the modern approach of tracing out the efficiency and integration in the return series. From the results of efficiency it was observed that the market lacked efficiency in terms of its past information. The results of integration test clearly indicates that there was a long memory in the returns of GCC Shariah during the study period. Hence it was concluded and proved that the returns of all GCC Equity Shariah were not informationally efficient but fractionally integrated during the study period.

Keywords: efficiency, Fama, GCC shariah, hurst exponent, integration, serial correlation

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Authors: Ying-Chang Yu, Yuan-Lung Lo

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Building envelope design is one of the most popular design fields of architectural profession in nowadays. The main design trend of such system is to highlight the designer's aesthetic intention from the outlook of building project. Due to the trend of current façade design, the building envelope contains more and more layers of components, such as double skin façade, photovoltaic panels, solar control system, or even ornamental components. These exterior components are designed for various functional purposes. Most researchers focus on how these exterior elements should be structurally sound secured. However, not many researchers consider these elements would help to improve the performance of façade system. When the exterior elements are deployed in large scale, it creates an additional layer outside of original façade system and acts like a porous interface which would interfere with the aerodynamic of façade surface in micro-scale. A standard façade performance consists with 'water penetration, air infiltration rate, operation force, and component deflection ratio', and these key performances are majorly driven by the 'Design Wind Load' coded in local regulation. A design wind load is usually determined by the maximum wind pressure which occurs on the surface due to the geometry or location of building in extreme conditions. This research was designed to identify the air damping phenomenon of micro turbulence caused by porous exterior layer leading to surface wind load reduction for improvement of façade system performance. A series of wind tunnel test on dynamic pressure sensor array covered by various scale of porous exterior skin was conducted to verify the effect of wind pressure reduction. The testing specimens were designed to simulate the typical building with two-meter extension offsetting from building surface. Multiple porous exterior skins were prepared to replicate various opening ratio of surface which may cause different level of damping effect. This research adopted 'Pitot static tube', 'Thermal anemometers', and 'Hot film probe' to collect the data of surface dynamic pressure behind porous skin. Turbulence and distributed resistance are the two main factors of aerodynamic which would reduce the actual wind pressure. From initiative observation, the reading of surface wind pressure was effectively reduced behind porous media. In such case, an actual building envelope system may be benefited by porous skin from the reduction of surface wind pressure, which may improve the performance of envelope system consequently.

Keywords: multi-layer facade, porous media, facade performance, turbulence and distributed resistance, wind tunnel test

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Authors: Cristian F.T. Montenegro, Luís F. N. Lourenço, Maurício B. C. Salles, Renato M. Monaro

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More PV systems have been connected to the electrical network each year. As the number of PV systems increases, some issues affecting grid operations have been identified. This paper studied the impacts related to changes in solar irradiance on a distribution/sub-transmission network, considering variations due to moving clouds and daily cycles. Using MATLAB/Simulink software, a solar farm of 30 MWp was built and then implemented to a test network. From simulations, it has been determined that irradiance changes can have a significant impact on the grid by causing voltage fluctuations outside the allowable thresholds. This work discussed some local control strategies and grid reinforcements to mitigate the negative effects of the irradiance changes on the grid.

Keywords: reactive power control, solar irradiance, utility-scale PV systems, voltage fluctuations

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Authors: Masoumeh Mofarrah, Amir NahanMoghadam

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Higher oil prices and increasing oil demand are main reasons for great attention to Enhanced Oil Recovery (EOR). Comprehensive researches have been accomplished to develop, appraise, and improve EOR methods and their application. Recently, Artificial Intelligence (AI) gained popularity in petroleum industry that can help petroleum engineers to solve some fundamental petroleum engineering problems such as reservoir simulation, EOR project risk analysis, well log interpretation and well test model selection. This study presents a historical overview of most popular AI tools including neural networks, genetic algorithms, fuzzy logic, and expert systems in petroleum industry and discusses two case studies to represent the application of two mentioned AI methods for selecting an appropriate EOR method based on reservoir characterization infeasible and effective way.

Keywords: artificial intelligence, EOR, neural networks, expert systems

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Authors: Faisal Asad Aburub

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Many organizations are investing in web applications and technologies in order to be competitive, some of them could not achieve its goals. The quality of web-based applications could play an important role for organizations to be competitive. So the aim of this study is to investigate the impact of quality of web-based applications to achieve a competitive advantage. A new model has been developed. An empirical investigation was performed on a banking sector in Jordan to test the new model. The results show that impact of web-based applications on competitive advantage is significant. Finally, further work is planned to validate and evaluate the proposed model using several domains.

Keywords: competitive advantage, web-based applications, empirical investigation, commercial banks in Jordan

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Authors: Ravinder Kataria, Jatinder Kumar, B. S. Pabla

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Ultrasonic machining is one of the most widely used non-traditional machining processes for machining of materials that are relatively brittle, hard, and fragile such as advanced ceramics, refractories, crystals, quartz etc. Present article has been targeted at investigating the impact of different experimental conditions (power rating, cobalt content, tool material, thickness of work piece, tool geometry, and abrasive grit size) on over cut in ultrasonic drilling of WC-Co composite material. Taguchi’s L-36 orthogonal array has been employed for conducting the experiments. Significant factors have been identified using analysis of variance (ANOVA) test. The experimental results revealed that abrasive grit size and tool material are most significant factors for over cut.

Keywords: ANOVA, abrasive grit size, Taguchi, WC-Co, ultrasonic machining

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Authors: A. Van Staden, A. Tolmie, E. Vorster

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Research confirms the multifaceted nature of spelling development and underscores the importance of both cognitive and linguistic skills that affect sound spelling development such as working and long-term memory, phonological and orthographic awareness, mental orthographic images, semantic knowledge and morphological awareness. This has clear implications for many South African English second language spellers (L2) who attempt to become proficient spellers. Since English has an opaque orthography, with irregular spelling patterns and insufficient sound/grapheme correspondences, L2 spellers can neither rely, nor draw on the phonological awareness skills of their first language (for example Sesotho and many other African languages), to assist them to spell the majority of English words. Epistemologically, this research is informed by social constructivism. In addition the researchers also hypothesized that the principles of the Overlapping Waves Theory was an appropriate lens through which to investigate whether L2 spellers could significantly improve their spelling skills via the implementation of an alternative route to spelling development, namely the orthographic route, and more specifically via the application of visual imagery. Post-test results confirmed the results of previous research that argues for the interactive nature of different cognitive and linguistic systems such as working memory and its subsystems and long-term memory, as learners were systematically guided to store visual orthographic images of words in their long-term lexicons. Moreover, the results have shown that L2 spellers in the experimental group (n = 9) significantly outperformed L2 spellers (n = 9) in the control group whose intervention involved phonological awareness (and coding) including the teaching of spelling rules. Consequently, L2 learners in the experimental group significantly improved in all the post-test measures included in this investigation, namely the four sub-tests of short-term memory; as well as two spelling measures (i.e. diagnostic and standardized measures). Against this background, the findings of this study look promising and have shown that, within a social-constructivist learning environment, learners can be systematically guided to apply higher-order thinking processes such as visual imagery to successfully store and retrieve mental images of spelling words from their output lexicons. Moreover, results from the present study could play an important role in directing research into this under-researched aspect of L2 literacy development within the South African education context.

Keywords: English second language spellers, phonological and orthographic coding, social constructivism, visual imagery as spelling strategy

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Authors: M. K. Mohd Safee, W. A. B. Wan Abas, F. Ibrahim, N. A. Abu Osman, N. A Abdul Malik

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This paper investigates the activity of the rectus femoris (RF) and biceps femoris (BF) in healthy subjects during salat (prostration) and specific exercise (squat exercise) using electromyography (EMG). A group of undergraduates aged between 19 to 25 years voluntarily participated in this study. The myoelectric activity of the muscles were recorded and analyzed. The finding indicated that there were contractions of the muscles during the salat and exercise with almost same EMG’s level. From the result, Wilcoxon’s Rank Sum test showed significant difference between prostration and squat exercise (p<0.05) but the differences was very small; RF (8.63%MVC) and BF (11.43%MVC). Therefore, salat may be useful in strengthening exercise and also in rehabilitation programs for lower limb activities. This pilot study conducted initial research into the biomechanical responses of human muscles in various positions of salat.

Keywords: electromyography, exercise, muscle, salat

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Authors: Dalila Chaid, Yacine Houmel, Mohamed Lamine Belloulou

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Peripheral neuropathy is a rare but worrying complication of peripheral local anaesthesia. It is caused either by needle contact with the nerve root or by the direct toxicity of local anaesthetics, leading to nerve damage, injury or irritation. Although uncommon, it remains a major concern for anaesthetists. The aim of the study was to assess the prevalence of nerve block-associated neuropathy in knee surgery and to identify the contributing factors in order to minimise the occurrence of this complication. The study also assessed the severity and evolution of lesions, as well as the factors leading to neuropathic pain. Methodology: It is a retrospective observational study on cases of neuropathy related to nerve blocks of the lower limb for knee surgery over a period of seven years (2016-2022). The study included a total of 6,000 patients Analyse the anaesthetic and neuropathic pain-related parameters received from these patients to determine the prevalence and severity of neuropathy. Findings: the prevalence of nerve block-related neuropathy in our study is 5.8‰ for the sciatic nerve and 0.9‰ for the femoral nerve. This was higher compared to the reported rates in the literature, which were between 0.0 to 5‰ for the Sciatic nerve and 0.0 to 3.4‰ for the femoral nerve. These findings highlight the importance of identifying and implementing an ideal anesthesia procedure to reduce the risk of neuropathy associated with nerve blocks. Theoretical Importance: The findings of this study contribute to the existing literature on peripheral neuropathy following locoregional anesthesia. By identifying the prevalence and severity of neuropathy related to nerve blocks, as well as the underlying factors, we provide valuable insights for anesthetists to improve patient safety. This study also emphasizes the need for compliance with technical safety rules to minimize the occurrence of neuropathy. Data Collection and Analysis Procedures: For this study, 25 clinics with retrospective data were collected of neuropathy associated with nerve blocks for knee surgery over a span of seven years. Parameters related to anaesthesia and neuropathic pain were analysed to determine prevalence,severity, and progression of neuropathy. Comparison of our results with the existing literature in order to assess their significance. Questions Addressed: This study aims to define the following points: 1. The prevalence of neuropathy associated with nerve blocks for knee surgery. 2. The factors underlying the development of neuropathy after nerve blocks. 3. Reducing the risk of neuropathy by complying with technical safety rules. 4. Assessing the severity and evolution of neuropathic pain in these cases. Conclusion: this study highlights the need for careful consideration and implementation of anesthesia procedures during nerve blocks for knee surgery. The prevalence of neuropathy linked to these blocks was higher compared to the literature, emphasizing the importance of identifying and minimizing contributing factors. Compliance with technical safety rules is crucial to reduce the risk of peripheral neuropathy. This study provides valuable insights to anesthetists and contributes to improving patient safety in the field of locoregional anesthesia.

Keywords: phantom limb, neuropathic pain, lower limb amputee, ultrasound-guided locoreginal anesthesia

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Authors: Robin Anderson, David Nisbet

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Nitrate, 3-nitro-1-propionic acid (NPA) and 3-nitro-1-propanol (NPOH) are biologically active chemicals that can accumulate naturally in rangeland grasses forages consumed by grazing cattle, sheep and goats. While toxic to livestock if accumulations and amounts consumed are high enough, particularly in animals having no recent exposure to the forages, these chemicals are known to be potent inhibitors of methane-producing bacteria inhabiting the rumen. Consequently, there is interest in examining their potential use as anti-methanogenic compounds to decrease methane emissions by grazing ruminants. Presently, rumen microbes, collected freshly from a cannulated Holstein cow maintained on 50:50 corn based concentrate:alfalfa diet were mixed (10 mL fluid) in 18 x 150 mm crimp top tubes with 0.5 of high nitrate-containing barley (Hordeum vulgare; containing 272 µmol nitrate per g forage dry matter), and NPA- or NPOH- containing milkvetch forages (Astragalus canadensis and Astragalus miser containing 80 and 174 soluble µmol NPA or NPOH/g forage dry matter respectively). Incubations containing 0.5 g alfalfa (Medicago sativa) were used as controls. Tubes (3 per each respective forage) were capped and incubated anaerobically (using oxygen free carbon dioxide) for 24 h at 39oC after which time amounts of total gas produced were measured via volume displacement and headspace samples were analyzed by gas chromatography to determine concentrations of hydrogen and methane. Fluid samples were analyzed by gas chromatography to measure accumulations of fermentation acids. A completely randomized analysis of variance revealed that the nitrate-containing barley and both the NPA- and the NPOH-containing milkvetches significantly decreased methane production, by > 50%, when compared to methane produced by populations incubated similarly with alfalfa (70.4 ± 3.6 µmol/ml incubation fluid). Accumulations of hydrogen, which are typically increased when methane production is inhibited, by incubations with the nitrate-containing barley and the NPA- and NPOH-containing milkvetches did not differ from accumulations observed in the alfalfa controls (0.09 ± 0.04 µmol/mL incubation fluid). Accumulations of fermentation acids produced in the incubations containing the high-nitrate barley and the NPA- and NPOH-containing milkvetches likewise did not differ from accumulations observed in incubations containing alfalfa (123.5 ± 10.8, 36.0 ± 3.0, 17.1 ± 1.5, 3.5 ± 0.3, 2.3 ± 0.2, 2.2 ± 0.2 µmol/mL incubation fluid for acetate, propionate, butyrate, valerate, isobutyrate, and isovalerate, respectively). This finding indicates the microbial populations did not compensate for the decreased methane production via compensatory changes in production of fermentative acids. Stoichiometric estimation of fermentation balance revealed that > 77% of reducing equivalents generated during fermentation of the forages were recovered in fermentation products and the recoveries did not differ between the alfalfa incubations and those with the high-nitrate barley or the NPA- or NPOH-containing milkvetches. Stoichiometric estimates of amounts of hexose fermented similarly did not differ between the nitrate-, NPA and NPOH-containing incubations and those with the alfalfa, averaging 99.6 ± 37.2 µmol hexose consumed/mL of incubation fluid. These results suggest that forages containing nitrate, NPA or NPOH may be useful to reduce methane emissions of grazing ruminants provided risks of toxicity can be effectively managed.

Keywords: nitrate, nitropropanol, nitropropionic acid, rumen methane emissions

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Authors: Christian Gaigl, Martin Mensinger

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Once a fire resistance rating is necessary, it has to be proofed that the load bearing behavior of a steel construction under the exposure of fire still fits the static demands. High costs of passive fire protection, which satisfies the requirements, frequently result in a concrete solution. To optimize these expenses, one method is to determine the critical temperature according to the Eurocode DIN EN 1993-1-2. For this purpose, positive effects of hot-dip galvanized surface layers on the temperature development of steel members in the accidental situation of fire exposure has been investigated. The test results show a significant better heating behavior of hot-dip galvanized steel components compared to normal steel specimen. This leads in many cases to a R30 (30 minutes of ISO-fire) fire protection requirement of unprotected steel members and therefore to an economic added value.

Keywords: fire resistance, hot-dip galvanizing, steel constructions, R30 requirement, emissivity

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Authors: B. X. Tchomeni, A. A. Alugongo, L. M. Masu

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An analytical 4-DOF nonlinear model of a de Laval rotor-stator system based on Energy Principles has been used theoretically and experimentally to investigate fault symptoms in a rotating system. The faults, namely rotor-stator-rub, crack and unbalance are modelled as excitations on the rotor shaft. Mayes steering function is used to simulate the breathing behaviour of the crack. The fault analysis technique is based on waveform signal, orbits and Fast Fourier Transform (FFT) derived from simulated and real measured signals. Simulated and experimental results manifest considerable mutual resemblance of elliptic-shaped orbits and FFT for a same range of test data.

Keywords: a breathing crack, fault, FFT, nonlinear, orbit, rotor-stator rub, vibration analysis

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Authors: Sharmin Sultana, Nicolas Nuns, Pardis Simon, Jean-Marc Giraudon, Jean-Francois Lamonior, Nathalie D. Geyter, Rino Morent

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Environmental issues, especially air pollution, have become a huge concern of environmental legislation as a consequence of growing awareness in our global world. In this regard, control of volatile organic compounds (VOCs) emission has become an important issue due to their potential toxicity, carcinogenicity, and mutagenicity. The research of innovative technologies for VOC abatement is stimulated to accommodate the new stringent standards in terms of VOC emission. One emerging strategy is the coupling of 2 existing complementary technologies, namely here non-thermal plasma (NTP) and heterogeneous catalysis, to get a more efficient process for VOC removal in air. The objective of this current work is to investigate the abatement of trichloroethylene (TCE-highly toxic chlorinated VOC) from moist air (RH=15%) as a function of time by combined use of multi-pin-to-plate negative DC corona/glow discharge with Fe-doped cryptomelanes catalyst downstream i.e. post plasma-catalysis (PPC) process. For catalyst alone case, experiments reveal that, initially, Fe doped cryptomelane (regardless the mode of Fe incorporation by co-precipitation (Fe-K-OMS-2)/ impregnation (Fe/K-OMS-2)) exhibits excellent activity to decompose TCE compared to cryptomelane (K-OMS-2) itself. A maximum obtained value of TCE abatement after 6 min is as follows: Fe-KOMS-2 (73.3%) > Fe/KOMS-2 (48.5) > KOMS-2 (22.6%). However, with prolonged operation time, whatever the catalyst under concern, the abatement of TCE decreases. After 111 min time of exposure, the catalysts can be ranked as follows: Fe/KOMS-2 (11%) < K-OMS-2 (12.3%) < Fe-KOMS-2 (14.5%). Clearly, this phenomenon indicates catalyst deactivation either by chlorination or by blocking the active sites. Remarkably, in PPC configuration (energy density = 60 J/L, catalyst temperature = 150°C), experiments reveal an enhanced performance towards TCE removal regardless the type of catalyst. After 6 min time on stream, the TCE removal efficiency amount as follows: K-OMS-2 (60%) < Fe/K-OMS-2 (79%) < Fe-K-OMS-2 (99.3%). The enhanced performances over Fe-K-OMS-2 catalyst are attributed to its high surface oxygen mobility and structural defects leading to high O₃ decomposition efficiency to give active species able to oxidize the plasma processed hazardous\by-products and the possibly remaining VOC into CO₂. Moreover, both undoped and doped catalysts remain strongly capable to abate TCE with time on stream. The TCE removal efficiencies of the PPC processes with Fe/KOMS-2 and KOMS-2 catalysts are not affected by time on stream indicating an excellent catalyst stability. When using the Fe-K-OMS-2 as catalyst, TCE abatement slightly reduces with time on stream. However, it is noteworthy to stress that still a constant abatement of 83% is observed during at least 30 minutes. These results prove that the combination of NTP with catalysts not only increases the catalytic activity but also allows to avoid, to some extent, the poisoning of catalytic sites resulting in an enhanced catalyst stability. In order to better understand the different surface processes occurring in the course of the total TCE oxidation in PPC experiments, a detailed X-ray Photoelectron Spectroscopy (XPS) and Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) study on the fresh and used catalysts is in progress.

Keywords: Fe doped cryptomelane, non-thermal plasma, plasma-catalysis, stability, trichloroethylene

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Authors: Mucip Tapan, Ali Ozvan, Ismail Akkaya

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This study investigated how the concrete confinement strength and axial load carrying capacity of reinforced concrete columns are affected by corrosion damage to the stirrups. A total of small-scale 12 test specimens were cast for evaluating the effect of stirrup corrosion on confinement strength of concrete. The results of this study show that the stirrup corrosion alone dramatically decreases the axial load carrying capacity of corroded reinforced concrete columns. Recommendations were presented for improved inspection practices which will allow estimating concrete confinement strength of corrosion-damaged reinforced concrete bridge columns.

Keywords: bridge, column, concrete, corrosion, inspection, stirrup reinforcement

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Authors: Xi Chen, King-Yip Cheng

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Hypercholesterolemia, characterized by high low-density lipoprotein cholesterol (LDL-C), raises cardiovascular events in patients with type 2 diabetes (T2D). Although several drugs, such as statin and PCSK9 inhibitors, are available for the treatment of hypercholesterolemia, they exert detrimental effects on glucose metabolism and hence increase the risk of T2D. On the other hand, the drugs used to treat T2D have minimal effect on improving the lipid profile. Therefore, there is an urgent need to develop treatments that can simultaneously improve glucose and lipid homeostasis. Adaptor protein phosphotyrosine interacting with PH domain and leucine zipper 2 (APPL2) causes insulin resistance in the liver and skeletal muscle via inhibiting insulin and adiponectin actions in animal models. Single-nucleotide polymorphisms in the APPL2 gene were associated with LDL-C, non-alcoholic fatty liver disease, and coronary artery disease in humans. The aim of this project is to investigate whether APPL2 antisense oligonucleotide (ASO) can alleviate dietary-induced T2D and hypercholesterolemia. High-fat diet (HFD) was used to induce obesity and insulin resistance in mice. GalNAc-conjugated APPL2 ASO (GalNAc-APPL2-ASO) was used to silence hepatic APPL2 expression in C57/BL6J mice selectively. Glucose, lipid, and energy metabolism were monitored. Immunoblotting and quantitative PCR analysis showed that GalNAc-APPL2-ASO treatment selectively reduced APPL2 expression in the liver instead of other tissues, like adipose tissues, kidneys, muscle, and heart. The glucose tolerance test and insulin sensitivity test revealed that GalNAc-APPL2-ASO improved glucose tolerance and insulin sensitivity progressively. Blood chemistry analysis revealed that the mice treated with GalNAc-APPL2-ASO had significantly lower circulating levels of total cholesterol and LDL cholesterol. However, there was no difference in circulating levels of high-density lipoprotein (HDL) cholesterol, triglyceride, and free fatty acid between the mice treated with GalNac-APPL2-ASO and GalNAc-Control-ASO. No obvious effect on food intake, body weight, and liver injury markers after GalNAc-APPL2-ASO treatment was found, supporting its tolerability and safety. We showed that selectively silencing hepatic APPL2 alleviated insulin resistance and hypercholesterolemia and improved energy metabolism in the dietary-induced obese mouse model, indicating APPL2 as a therapeutic target for metabolic diseases.

Keywords: APPL2, antisense oligonucleotide, hypercholesterolemia, type 2 diabetes

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Authors: Hao-Jun Hong, Jung-Tang Huang

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The world is gradually becoming an aging society, and with the lack of laboring forces, this phenomenon is affecting the nation’s economy growth. Although nursing centers are booming in recent years, the lack of medical resources are yet to be resolved, thus creating an innovative wearable medical device could be a vital solution. This research is focused on the design and development of a wearable device which obtains a more precise heart failure measurement than products on the market. The method used by the device is based on the sensor fusion and big data algorithm. From the test result, the modified structure of wearable device can significantly decrease the MA (Motion Artifact) and provide users a more cozy and accurate physical monitor experience.

Keywords: big data, heart failure, motion artifact, sensor fusion, wearable medical device

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Authors: Insiya Bhalloo

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It is quite common in the Muslim faith for non-Arabic speakers to be able to convert written Arabic, especially Quranic Arabic, into a phonological code without significant semantic or syntactic knowledge. This is due to prior experience learning to read the Quran (a religious text written in Classical Arabic), from a very young age such as via enrolment in Quranic Arabic classes. As compared to native speakers of Arabic, these Arabic readers do not have a comprehensive morpho-syntactic knowledge of the Arabic language, nor can understand, or engage in Arabic conversation. The study seeks to investigate whether mere phonological experience (as indicated by the Arabic readers’ experience with Arabic phonology and the sound-system) is sufficient to cause phonological-interference during word recognition of previously-heard words, despite the participants’ non-native status. Both native speakers of Arabic and non-native speakers of Arabic, i.e., those individuals that learned to read the Quran from a young age, will be recruited. Each experimental session will include two phases: An exposure phase and a test phase. During the exposure phase, participants will be presented with Arabic words (n=40) on a computer screen. Half of these words will be common words found in the Quran while the other half will be words commonly found in Modern Standard Arabic (MSA) but either non-existent or prevalent at a significantly lower frequency within the Quran. During the test phase, participants will then be presented with both familiar (n = 20; i.e., those words presented during the exposure phase) and novel Arabic words (n = 20; i.e., words not presented during the exposure phase. ½ of these presented words will be common Quranic Arabic words and the other ½ will be common MSA words but not Quranic words. Moreover, ½ the Quranic Arabic and MSA words presented will be comprised of nouns, while ½ the Quranic Arabic and MSA will be comprised of verbs, thereby eliminating word-processing issues affected by lexical category. Participants will then determine if they had seen that word during the exposure phase. This study seeks to investigate whether long-term phonological memory, such as via childhood exposure to Quranic Arabic orthography, has a differential effect on the word-recognition capacities of native Arabic speakers and Arabic readers; we seek to compare the effects of long-term phonological memory in comparison to short-term phonological exposure (as indicated by the presentation of familiar words from the exposure phase). The researcher’s hypothesis is that, despite the lack of lexical knowledge, early experience with converting written Quranic Arabic text into a phonological code will help participants recall the familiar Quranic words that appeared during the exposure phase more accurately than those that were not presented during the exposure phase. Moreover, it is anticipated that the non-native Arabic readers will also report more false alarms to the unfamiliar Quranic words, due to early childhood phonological exposure to Quranic Arabic script - thereby causing false phonological facilitatory effects.

Keywords: modern standard arabic, phonological facilitation, phonological memory, Quranic arabic, word recognition

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Authors: Mohsen Shirani, Micaela Demichela

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During the last decades, a number of food crises such as Bovine Spongiform Encephalopathy (BSE), Mad-Cow disease, Dioxin in chicken food, Food-and-Mouth Disease (FMD), have certainly inflicted the reliability of the food industry. Consequently, the trend in applying different scientific methods of risk assessment in food safety has obtained more attentions in the academic and practice. However, lack of practical approach considering entire food supply chain is tangible in the academic literature. In this regard, this paper aims to apply risk assessment tool (FMEA) with integration of Human Factor along the entire supply chain of food production and test the method in a case study of Diary production, and analyze its results.

Keywords: FMEA, food supply chain, risk assessment, human factor

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Authors: Alireza Rezagholilou

Abstract:

Moisture susceptibility of bituminous mixes directly affect the stripping of asphalt layers. The majority of relevant test methods are mechanical methods with low repeatability and consistency of results. Thus, this research aims to evaluate the physicochemical interactions of bitumen and aggregates based on the wettability concept. As such, the surface energies of components at the interface are measured by contact angle method. That gives an opportunity to investigate the adhesion properties of multiple mineral fillers at various percentages to explore the best dosage in the mix. Three types of fillers, such as hydrated lime, ground lime and rock powder, are incorporated into the bitumen mix for a series of sessile drop tests for both aggregates and binders. Results show the variation of adhesion properties versus filler (%).

Keywords: adhesion, contact angle, filler, surface energy, moisture susceptibility

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Authors: Hussam Elias, Ninovic Perez, Holger Hirsch

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The completion of the EMC regulations worldwide is growing steadily as the usage of electronics in our daily lives is increasing more than ever. In this paper, we introduce a novel method to perform the final phase of Electromagnetic compatibility (EMC) measurement and to reduce the required test time according to the norm EN 55032 by using a developed tool and the conventional neural network(CNN). The neural network was trained using real EMC measurements, which were performed in the Semi Anechoic Chamber (SAC) by CETECOM GmbH in Essen, Germany. To implement our proposed method, we wrote software to perform the radiated electromagnetic interference (EMI) measurements and use the CNN to predict and determine the position of the turntable that meets the maximum radiation value.

Keywords: conventional neural network, electromagnetic compatibility measurement, mean absolute error, position error

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Authors: Ali Adamu

Abstract:

Teachers’ background characteristics as a correlate of students’ achievement in Mathematics were studied in Gombe State. Pearson Product Moment Correlation Coefficient was used for the analysis. Five Hundred and Twelve (512) students and 20 teachers from 12 schools in Gombe State of Nigeria were used for the study. Students’ Achievement Tests and Mathematics Teachers’ backgrounds were instruments for the study. The findings indicated that teachers’ qualifications, experience of the teacher, and teachers’ personalities had a positive correlation with students’ achievement. Recommendations are made, which include allowing the teachers to go for training as well as the government should ensure recruiting teachers that have experience in the teaching job.

Keywords: achievement-test, teachers’ personality, teaching mathematics, teacher-background

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Authors: P. Vit, J. Uddin, V. Zuccato, F. Maza, E. Schievano

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In Ecuador honeys are produced by Apis mellifera and stingless bees (Meliponini). We studied honey produced in beeswax combs by Apis mellifera, and honey produced in pots by Geotrigona and Scaptotrigona bees. Chloroform extracts of honey were obtained for fast NMR spectra. The 1D spectra were acquired at 298 K, with a 600 MHz NMR Bruker instrument, using a modified double pulsed field gradient spin echoes (DPFGSE) sequence. Signals of 1H NMR spectra were integrated and used as inputs for PCA, PLS-DA analysis, and labelled sets of classes were successfully identified, enhancing the separation between the three groups of honey according to the entomological origin: A. mellifera, Geotrigona and Scaptotrigona. This procedure is therefore recommended for authenticity test of honey in Ecuador.

Keywords: Apis mellifera, honey, 1H NMR, entomological origin, meliponini

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Authors: Anupam Saxena, Achin Agrawal, Rishabh Shukla, S. Mandal

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It is quite important that the properties of structural elements do not change significantly before and after cracking, and if they do, it adversely affects the structure. Corrosion in rebars causes cracking in concrete which can lead to the change in properties of beam. In the present study, two RC beams with same flexural strength but with different reinforcement arrangements are considered and modelling of cracks of RC beams has been done at different degrees of corrosion in the case of delamination using boundary conditions of Three Point Bending Test. Finite Element Analysis (FEA) has been done at different degree of corrosion to observe the variation of different parameters like modal frequency, Elasticity and Flexural strength in case of delamination. Also, the comparison between two different RC arrangements is made to conclude which one of them is more suitable.

Keywords: delamination, elasticity, FEA, flexural strength, modal frequency, RC beam

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Authors: Akram Abi, Mohammad Hossein Sarrafzadeh

Abstract:

Because of their several advantages over chemical surfactants, biosurfactants have given rise to a growing interest in the past decades. Advantages such as lower toxicity, higher biodegradability, higher selectivity and applicable at extreme temperature and pH which enables them to be used in a variety of applications such as: enhanced oil recovery, environmental and pharmaceutical applications, etc. Bacillus subtilis produces a cyclic lipopeptide, called surfactin, which is one of the most powerful biosurfactants with ability to decrease surface tension of water from 72 mN/m to 27 mN/m. In addition to its biosurfactant character, surfactin exhibits interesting biological activities such as: inhibition of fibrin clot formation, lyses of erythrocytes and several bacterial spheroplasts, antiviral, anti-tumoral and antibacterial properties. Surfactin is an antibiotic substance and has been shown recently to possess anti-HIV activity. However, application of biosurfactants is limited by their high production cost. The cost can be reduced by optimizing biosurfactant production using cheap feed stock. Utilization of inexpensive substrates and unconventional carbon sources like urban or agro-industrial wastes is a promising strategy to decrease the production cost of biosurfactants. With suitable engineering optimization and microbiological modifications, these wastes can be used as substrates for large-scale production of biosurfactants. As an effort to fulfill this purpose, in this work we have tried to utilize olive oil as second carbon source and also yeast extract as second nitrogen source to investigate the effect on both biomass and biosurfactant production improvement in Bacillus subtilis cultures. Since the turbidity of the culture was affected by presence of the oil, optical density was compromised and no longer could be used as an index of growth and biomass concentration. Therefore, cell Dry Weight measurements with applying necessary tactics for removing oil drops to prevent interference with biomass weight were carried out to monitor biomass concentration during the growth of the bacterium. The surface tension and critical micelle dilutions (CMD-1, CMD-2) were considered as an indirect measurement of biosurfactant production. Distinctive and promising results were obtained in the cultures containing olive oil compared to cultures without it: more than two fold increase in biomass production (from 2 g/l to 5 g/l) and considerable reduction in surface tension, down to 40 mN/m at surprisingly early hours of culture time (only 5hr after inoculation). This early onset of biosurfactant production in this culture is specially interesting when compared to the conventional cultures at which this reduction in surface tension is not obtained until 30 hour of culture time. Reducing the production time is a very prominent result to be considered for large scale process development. Furthermore, these results can be used to develop strategies for utilization of agro-industrial wastes (such as olive oil mill residue, molasses, etc.) as cheap and easily accessible feed stocks to decrease the high costs of biosurfactant production.

Keywords: agro-industrial waste, bacillus subtilis, biosurfactant, fermentation, second carbon and nitrogen source, surfactin

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Authors: Reza Mohammadi

Abstract:

Using quartic spline, we develop a method for numerical solution of singularly perturbed two-point boundary-value problems. The purposed method is fourth-order accurate and applicable to problems both in singular and non-singular cases. The convergence analysis of the method is given. The resulting linear system of equations has been solved by using a tri-diagonal solver. We applied the presented method to test problems which have been solved by other existing methods in references, for comparison of presented method with the existing methods. Numerical results are given to illustrate the efficiency of our methods.

Keywords: second-order ordinary differential equation, singularly-perturbed, quartic spline, convergence analysis

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Authors: Roli Saini, Pradeep Kumar

Abstract:

A coagulation/flocculation process was adopted for the reduction of carbamate insecticide (carbofuran) from aqueous solution. Ferric chloride (FeCl₃) was used as a coagulant to treat the carbofuran. To exploit the reduction efficiency of pesticide concentration and COD, the jar-test experiments were carried out and process was optimized through response surface methodology (RSM). The effects of two independent factors; i.e., FeCl₃ dosage and pH on the reduction efficiency were estimated by using central composite design (CCD). The initial COD of the 30 mg/L concentrated solution was found to be 510 mg/L. Results exposed that the maximum reduction occurred at an optimal condition of FeCl₃ = 80 mg/L, and pH = 5.0, from which the reduction of concentration and COD 75.13% and 65.34%, respectively. The present study also predicted that the obtained regression equations could be helpful as the theoretical basis for the coagulation process of pesticide wastewater.

Keywords: carbofuran, coagulation, optimization, response surface methodology

Procedia PDF Downloads 310