Search results for: oxidation mechanisms

Authors: Grmanesh Gidey Kahsay

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In modern technical engineering applications, quality is defined in two ways. The first one is that quality is the parameter that measures a product or service’s characteristics to meet and satisfy the pre-stated or fundamental needs (reliability, durability, serviceability). The second one is the quality of a product or service free of any defect or deficiencies. The American Society for Quality (ASQ) describes quality as a pursuit of optimal solutions to confirm successes and fulfillment to be accountable for the product or service's requirements and expectations. This article focuses on quality engineering tools in modern industrial applications. Quality engineering is a field of engineering that deals with the principles, techniques, models, and applications of the product or service to guarantee quality. Including the entire activities to analyze the product’s design and development, quality engineering emphasizes how to make sure that products and services are designed and developed to meet consumers’ requirements. This episode acquaints with quality tools such as quality systems, auditing, product design, and process control. The finding presents thoughts that aim to improve quality engineering proficiency and effectiveness by introducing essential quality techniques and tools in some selected industries.

Keywords: essential quality tools, quality systems and models, quality management systems, and quality assurance

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Authors: Ahmad N. Abu-Baker

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This study investigated the corrosion of a group of heritage silver-copper alloy coins and their conservation treatment by potentiostatic methods. The corrosion products of the coins were characterized by a combination of scanning electron microscopy/ energy-dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffraction (XRD) analyses. Cathodic polarization curves, measured by linear sweep voltammetry (LSV), also identified the corrosion products and the working conditions to treat the coins using a potentiostatic reduction method, which was monitored by chronoamperometry. The corrosion products showed that the decay mechanisms were dominated by selective attack on the copper-rich phases of the silver-copper alloys, which is consistent with an internal galvanic corrosion phenomenon, which leads to the deposition of copper corrosion products on the surface of the coins. Silver chloride was also detected on the coins, which reflects selective corrosion of the silver-rich phases under different chemical environments. The potentiostatic treatment showed excellent effectiveness in determining treatment parameters and monitoring the reduction process of the corrosion products on the coins, which helped to preserve surface details in the cleaning process and to prevent over-treatment.

Keywords: silver alloys, corrosion, conservation, heritage

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Authors: Ritu Chaturvedi, Mayank Varun, M. S. Paul

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Heavy metal contamination of soil is a growing area of concern since the soil is the matrix that supports flora and impacts humans directly. Phytoremediation of contaminated sites is gaining popularity due to its cost effectiveness and solar driven nature. Some hyperaccumulators have been identified for their potential. Metal-accumulating plants have various mechanisms to cope up with stress and one of them is increasing antioxidative capacity. The aim of this research is to assess the effect of Vesicular arbuscular mycorrhiza (VAM) application on the phytoremedial potential of Solanum melongena (Eggplant) and level of photosynthetic pigments along with antioxidative enzymes. Results showed that VAM application increased shoot length, root proliferation pattern of plants. The level of photosynthetic pigments, proline, SOD, CAT, APX altered significantly in response to heavy metal treatment. In conclusion, VAM increased the uptake of heavy metals which lead to the activation of the defense system in plants for scavenging free radicals.

Keywords: heavy metal, phytoextraction, phytostabilization, reactive oxygen species

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Authors: Anita Kushwaha

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We propose a new evolutionary computational model called Artificial Reproduction System which is based on the complex process of meiotic reproduction occurring between male and female cells of the living organisms. Artificial Reproduction System is an attempt towards a new computational intelligence approach inspired by the theoretical reproduction mechanism, observed reproduction functions, principles and mechanisms. A reproductive organism is programmed by genes and can be viewed as an automaton, mapping and reducing so as to create copies of those genes in its off springs. In Artificial Reproduction System, the binding mechanism between male and female cells is studied, parameters are chosen and a network is constructed also a feedback system for self regularization is established. The model then applies Mendel’s law of inheritance, allele-allele associations and can be used to perform data analysis of imbalanced data, multivariate, multiclass and big data. In the experimental study Artificial Reproduction System is compared with other state of the art classifiers like SVM, Radial Basis Function, neural networks, K-Nearest Neighbor for some benchmark datasets and comparison results indicates a good performance.

Keywords: bio-inspired computation, nature- inspired computation, natural computing, data mining

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Authors: Hanene Akrout, Ines Elaissaoui, Sabrina Grassini, Daniele Fulginiti, Latifa Bousselmi

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The main objective of this work is to investigate the efficiency of depollution power related to PbO₂ layer deposited onto a stainless steel (SS) substrate with SiOx as interlayer. The elaborated electrode was used as anode for anodic oxidation of wastewater containing Amaranth dye, as recalcitrant organic pollutant model. SiOx interlayer was performed using Plasma Enhanced Chemical Vapor Deposition ‘PECVD’ in plasma fed with argon, oxygen, and tetraethoxysilane (TEOS, Si precursor) in different ratios, onto the SS substrate. PbO₂ layer was produced by pulsed electrodeposition on SS/SiOx. The morphological of different surfaces are depicted with Field Emission Scanning Electron Microscope (FESEM) and the composition of the lead oxide layer was investigated by X-Ray Diffractometry (XRD). The results showed that the SiOx interlayer with more rich oxygen content improved better the nucleation of β-PbO₂ form. Electrochemical Impedance Spectroscopy (EIS) measurements undertaken on different interfaces (at optimized conditions) revealed a decrease of Rfilm while CPE film increases for SiOx interlayer, characterized by a more inorganic nature and deposited in a plasma fed by higher O2-to-TEOS ratios. Quantitative determinations of the Amaranth dye degradation rate were performed in terms of colour and COD removals, reaching a 95% and an 80% respectively removal at pH = 2 in 300 min. Results proved the improvement of the degradation wastewater containing the amaranth dye. During the electrolysis, the Amaranth dye solution was sampled at 30 min intervals and analyzed by ‘High-performance Liquid Chromatography’ HPLC. The gradual degradation of the Amaranth dye confirmed by the decrease in UV absorption using the SS/SiOx(20:20:1)/PbO₂ anode, the reaction exhibited an apparent first-order kinetic for electrolysis time of 5 hours, with an initial rate constant of about 0.02 min⁻¹.

Keywords: electrochemical treatment, PbO₂ anodes, COD removal, plasma

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Authors: Marian Sorin Ionescu, Olivia Negoita, Cosmin Dobrin

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This scientific communication reports and discusses learning models adaptable to modern business problems and models specific to digital concepts and paradigms. In the PAC (probably approximately correct) learning model approach, in which the learning process begins by receiving a batch of learning examples, the set of learning processes is used to acquire a hypothesis, and when the learning process is fully used, this hypothesis is used in the prediction of new operational examples. For complex business models, a lot of models should be introduced and evaluated to estimate the induced results so that the totality of the results are used to develop a predictive rule, which anticipates the choice of new models. In opposition, for online learning-type processes, there is no separation between the learning (training) and predictive phase. Every time a business model is approached, a test example is considered from the beginning until the prediction of the appearance of a model considered correct from the point of view of the business decision. After choosing choice a part of the business model, the label with the logical value "true" is known. Some of the business models are used as examples of learning (training), which helps to improve the prediction mechanisms for future business models.

Keywords: machine learning, business models, convex analysis, online learning

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Authors: Wafa Nouari

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This study compares four novels written in English by Algerian writers: Donkey Heart Monkey Mind by Djaffar Chetouane, Pebble in the River by Noufel Bouzeboudja, Sophia in the White City by Belkacem Mezghouchene, and The Inner Light of Darkness by Iheb Kharab. It applies comparative research methods and cultural studies as the literary theory to analyze how these novels depict Algeria’s culture, history, and identity through their genre, style, tone, perspective, and structure. It identifies some common themes shared by them, such as the quest for freedom and dignity in a context of oppression and colonialism and the use of storytelling, imagination, and creativity as coping mechanisms for trauma and adversity. It also highlights their differences in terms of style, genre, setting, period, and perspectives. It concludes that these novels offer rich and diverse insights into Algeria and its multifaceted reality. It also discusses some limitations and challenges related to Algerian literature in English and suggests some directions for future research.

Keywords: Algeri an literature in English, comparative research methods, cultural studies, diversity and complexity

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Authors: Akbar Farahani, Afsaneh Hassani, Peyman M. Farkhondeh

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Human Resource Management as one of the core processes of the project-based companies, despite its key role in the success and competitive advantage, is relatively unknown. In the project-based companies, due to the accelerated movement of knowledge in the work activities and the temporary nature of the project, the need to develop mechanisms for achieving optimal management of this issues is very challenging. Approach to human resource management in these companies evolves with goals, strategies, and operational processes. Therefore, the need for appropriate tools to facilitate implementation of the optimized human resource management in the project is more than before,Which currently with the development of information technology and modern communication, appropriate to address the optimal approach for dynamic management of human resources in the project have been provided.This is done by using the referral system implemented in Mahab GCE that provides 1: the ability to use humans in projects without geographic limitation and 2:information on the activities and outcomes of referrals.Furthermore, by using this system, recording the lessons learned after any particular activity on projects,accessing quantitative information, procedures, documentation of learned practices that have been stored in the data base as well as using them in future projects is provided.

Keywords: human resource management, project base company, ERP, referrals system

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Authors: I. Benmehdi, O. Hasnaoui, N. Hachemi, M. Bouazza

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The Understanding of the mechanisms structuring of plant diversity in the region of Tlemcen (western Algeria) is a related problem. The current floristic composition of different groups in Pistacia lentiscus L. resulting from the combination of human and climate action. This study is devoted to biodiversity inventory and phytogeographic characterization of Pistacia lentiscus groups in the Honaine coastal (western Algeria). The floristic inventory (150 levels) made in three stations of the study area allowed to count a 109 species belonging to 44 families of vascular plants. The biogeographical analysis of the Pistacia lentiscus groups reveals the most representative elements. The Mediterranean elements are numerically the most dominant with 39.45% represented by: Pistacia lentiscus, Cistus monspeliensis, Plantago lagopus, Linum strictum, Echium vulgare; followed by the western Mediterranean elements with 10.09% and are represented by: Chamaerops humilis, Lavandula dentata, Ampelodesma mauritanicum and Iris xyphium. However, this phytotaxonomic wealth is exposed to anthropogenic impact causing its disruption see its decline.

Keywords: Pistacia lentiscus L., phytodiversity, phytogeography, honaine, western Algeria

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Authors: Hee Sun (Sunny) Choi, Gerhard Bruyns, Wang Zhang, Sky Cheng, Saijal Sharma

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This research addresses the need for a comprehensive framework that can guide the design and assessment of multi-level public spaces and public realms and their impact on the built environment. The study aims to understand and measure the neural mechanisms involved in this process. By doing so, it can lay the foundation for vertical and volumetric urbanism and ensure consistency and excellence in the field while also supporting scientific research methods for urban design with cognitive neuroscientists. To investigate these aspects, the paper focuses on the neighborhood scale in Hong Kong, specifically examining multi-level public spaces and quasi-public spaces within both commercial and residential complexes. The researchers use predictive Artificial Intelligence (AI) as a methodology to assess and comprehend the applicability of the urban design framework for vertical and volumetric urbanism. The findings aim to identify the factors that contribute to successful public spaces within a vertical living environment, thus introducing a new typology of public spaces.

Keywords: vertical urbanism, scientific research methods, spatial cognition, urban design guideline

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Authors: Aofan Liu, Qianqian Tan, Burra Venkata Durga Kumar

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Data security is of the utmost importance in the healthcare area, as sensitive patient information is constantly sent around and analyzed by many different parties. The use of federated learning, which enables data to be evaluated locally on devices rather than being transferred to a central server, has emerged as a potential solution for protecting the privacy of user information. To protect against data breaches and unauthorized access, federated learning alone might not be adequate. In this context, the application of blockchain technology could provide the system extra protection. This study proposes a distributed federated learning system that is built on blockchain technology in order to enhance security in healthcare. This makes it possible for a wide variety of healthcare providers to work together on data analysis without raising concerns about the confidentiality of the data. The technical aspects of the system, including as the design and implementation of distributed learning algorithms, consensus mechanisms, and smart contracts, are also investigated as part of this process. The technique that was offered is a workable alternative that addresses concerns about the safety of healthcare while also fostering collaborative research and the interchange of data.

Keywords: data privacy, distributed system, federated learning, machine learning

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Authors: Celia Marilia Martins, Sonia I. V. Guilundo, Iris M. Victorino, Antonio O. Quilambo

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In Mozambique rapid industrialization (mining, aluminium and cement activities) and urbanization processes has led to the incorporation of heavy metals on soil, thus degrading not only the quality of the environment, but also affecting plants, animals and human healthy. Several methods have been used to remediate contaminated soils, but most of them are costly and difficult to get optimum results. Currently, phytoremediation is an effective and affordable technological solution used to extract or remove inactive metals from contaminated soil. Phytoremediation is the use of plants to clean up a contamination from soils, sediments, and water. This technology is environmental friendly and potentially cost effective. The present investigation summarised the potential of edible vegetable to grow under the high level of heavy metals such as lead and zinc. The plants used in these studies include Tomatoes, lettuce and Soya beans. The studies have shown that edible plants can be grown under the high level of heavy metals on the soil. Further investigations are identifying mechanisms used by plants to ensure a safe and sustainable use for remediation of contaminated soils by heavy metals.

Keywords: contaminated soil, edible plants, heavy metals, phytoremediation

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Authors: Madihah Shukri

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Research examining whether eating behaviour is related to unhealthy or healthy eating pattern is required to explain the mechanisms underlying obesity, and to inform health intervention aim to prevent and treat obesity. The purpose of this study was to investigate the relationship between eating behaviours and nature of food consumption. Methods: This was a cross-sectional study of 588 adults (males = 231 and females = 357). The Dutch Eating Behaviour Questionnaire (DEBQ) was used to measure restrained, emotional and external eating. Nature of food consumption was assessed by self-reported consumption of fruit and vegetables, sweet food, junk food and snacking. Results: Results revealed that emotional eating was found to be the principal predictor of the consumption of less healthy food (sweet food, junk food and snacking), while external eating predicted sweet food intake. Intake of fruit and vegetable was associated with restrained eating. In light of the significant associations between eating behaviour and nature of food consumption, acknowledging individuals eating styles can have implications for tailoring effective nutritional programs in the context of obesity and chronic disease epidemic.

Keywords: eating behaviour, food consumption, adult, Malaysia

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Authors: Xiaoqing Liu, Kurt Friese, Karsten Rinke

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Lacustrine sediment archives rich paleoenvironmental information in lake and surrounding environment. Additionally, modern sediment is used as an effective medium for the monitoring of lake. Organic carbon in sediment is a heterogeneous mixture with varying turnover times and qualities which result from the different biogeochemical processes in the deposition of organic material. Therefore, the isolation of different carbon pools is important for the research of lacustrine condition in the lake. However, the numeric available fractionation procedures can hardly yield homogeneous carbon pools on terms of stability and age. In this work, a multi-step fractionation protocol that treated sediment with hot water, HCl, H2O2 and Na2S2O8 in sequence was adopted, the treated sediment from each step were analyzed for the isotopic and structural compositions with Isotope Ratio Mass Spectrometer coupled with element analyzer (IRMS-EA) and Solid-state 13C Nuclear Magnetic Resonance (NMR), respectively. The sequential extractions with hot-water, HCl, and H2O2 yielded a more homogeneous and C3 plant-originating OC fraction, which was characterized with an atomic C/N ratio shift from 12.0 to 20.8, and 13C and 15N isotopic signatures were 0.9‰ and 1.9‰ more depleted than the original bulk sediment, respectively. Additionally, the H2O2- resistant residue was dominated with stable components, such as the lignins, waxes, cutans, tannins, steroids and aliphatic proteins and complex carbohydrates. 6M HCl in the acid hydrolysis step was much more effective than 1M HCl to isolate a sedimentary OC fraction with higher degree of homogeneity. Owing to the extremely high removal rate of organic matter, the step of a Na2S2O8 oxidation is only suggested if the isolation of the most refractory OC pool is mandatory. We conclude that this multi-step chemical fractionation procedure is effective to isolate more homogeneous OC pools in terms of stability and functional structure, and it can be used as a promising method for OC pools fractionation of sediment or soil in future lake research.

Keywords: 13C-CPMAS-NMR, 13C signature, lake sediment, OC fractionation

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Authors: Nabil Abaab, Dhaou Akrout, Riadh Ahmadi, Mabrouk Montacer

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The study of fluid pressure and its evolution have a critical importance as they lead to understanding the tectonic history of the region. Therefore, the present work focuses on a microtectonic study of tectonic and hydraulic fracture at the anticline structure of Zemlet El Beidha (North Chott range). The study and the analysis of several stations of tectonic and hydraulic fracture allow revealing the witnesses of a paléosurpression in the deposits of Lower Cretaceous (Bouhedma Formation). In fact, we noticed that the overpressure is directly involved in the creation of various types of fractures as evidenced by the different measures and the stereographic projections. Thus, the orientations of fibers of mineralization that fills the Beefs type fracture have the same direction as the main constraint. Furthermore, we discussed the different overpressure build-up mechanisms. The results showed that tectonics is likely, responsible for this anomaly. This is confirmed by the description of the fibers and the projection of the different measurements of Beefs. The mineralization transformation from gypsum to anhydrite is heavily involved in this stress regime especially in the presence of all necessary conditions of dehydration of gypsum.

Keywords: Zemlet El Beidha, overpressure, tectonic fracture, hydraulic fracture, gypsum beefs

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Authors: P. Joshna, Souvik Kundu

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Detection of ultraviolet (UV) radiation is very important as it has exhibited a profound influence on humankind and other existences, including military equipment. In this work, a self-powered UV photodetector was reported based on oxides heterojunctions. The thin films of p-type nickel oxide (NiO) and n-type reduced graphene oxide (rGO) were used for the formation of p-n heterojunction. Low-Cost and low-temperature chemical synthesis was utilized to prepare the oxides, and the spin coating technique was employed to deposit those onto indium doped tin oxide (ITO) coated glass substrates. The top electrode platinum was deposited utilizing physical vapor evaporation technique. NiO offers strong UV absorption with high hole mobility, and rGO prevents the recombination rate by separating electrons out from the photogenerated carriers. Several structural characterizations such as x-ray diffraction, atomic force microscope, scanning electron microscope were used to study the materials crystallinity, microstructures, and surface roughness. On one side, the oxides were found to be polycrystalline in nature, and no secondary phases were present. On the other side, surface roughness was found to be low with no pit holes, which depicts the formation of high-quality oxides thin films. Whereas, x-ray photoelectron spectroscopy was employed to study the chemical compositions and oxidation structures. The electrical characterizations such as current-voltage and current response were also performed on the device to determine the responsivity, detectivity, and external quantum efficiency under dark and UV illumination. This p-n heterojunction device offered faster photoresponse and high on-off ratio under 365 nm UV light illumination of zero bias. The device based on the proposed architecture shows the efficacy of the oxides heterojunction for efficient UV photodetection under zero bias, which opens up a new path towards the development of self-powered photodetector for environment and health monitoring sector.

Keywords: chemical synthesis, oxides, photodetectors, spin coating

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Authors: Erwin Stolz, Hannes Mayerl, Anja Waxenegger, Wolfgang Freidl

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Research has often found poverty associated with adverse health outcomes, but it is unclear which (interplay of) mechanisms actually translate low economic resources into poor physical health. The goal of this study was to assess the impact of educational, material, psychosocial and behavioural factors in explaining the poverty-health association in old age. We analysed 28,360 observations from 11,390 community-dwelling respondents (65+) from the Survey of Health, Ageing and Retirement in Europe (SHARE, 2004-2013, 10 countries). We used multilevel growth curve models to assess the impact of combined income- and asset poverty risk on old age frailty index levels and trajectories. In total, 61.8% of the variation of poverty risk on frailty levels could be explained by direct and indirect effects, thereby highlighting the role of material and particularly psychosocial factors, such as perceived control and social isolation. We suggest strengthening social policy and public health efforts in order to fight poverty and its deleterious effects from early age on and to broaden the scope of interventions with regard to psychosocial factors.

Keywords: frailty, health inequality, old age, poverty

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Authors: Zhongyang Sun, Shu Zhang

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In osteoblasts, L-type voltage sensitive calcium channels (LTCCs), especially the Cav1.2 LTCCs, play fundamental roles in cellular responses to external stimuli including both mechanical forces and hormonal signals. Several lines of evidence have revealed that the density of bone is increased and the resorption of bone is decreased when these calcium channels in osteoblasts are activated. And numerous studies have shown that mechanical loading promotes bone formation in the modeling skeleton, whereas removal of this stimulus in microgravity results in a reduction in bone mass. However, the effect of microgravity on LTCCs in osteoblasts is still unknown. The aim of this study was to determine whether microgravity exerts influence on LTCCs in osteoblasts and the possible mechanisms underlying. In this study, we demonstrate that simulated microgravity substantially inhibits LTCCs in osteoblast by suppressing the expression of Cav1.2. Then we show that the up-regulation of miR-103 is involved in the down-regulation of Cav1.2 expression and inhibition of LTCCs by simulated microgravity in osteoblasts. Our study provides a novel mechanism of simulated microgravity-induced adverse effects on osteoblasts, offering a new avenue to further investigate the bone loss caused by microgravity.

Keywords: L-type voltage sensitive calcium channels, Cav1.2, osteoblasts, microgravity

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Authors: Haozhe Xiang

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With the rise of the Internet of Things era, intelligent products are gradually integrating into people's lives. Pedestrian trajectory prediction has become a key issue, which is crucial for the motion path planning of intelligent agents such as autonomous vehicles, robots, and drones. In the current technological context, deep learning technology is becoming increasingly sophisticated and gradually replacing traditional models. The pedestrian trajectory prediction algorithm combining neural networks and attention mechanisms has significantly improved prediction accuracy. Based on in-depth research on deep learning and pedestrian trajectory prediction algorithms, this article focuses on physical environment modeling and learning of historical trajectory time dependence. At the same time, social interaction between pedestrians and scene interaction between pedestrians and the environment were handled. An improved pedestrian trajectory prediction algorithm is proposed by analyzing the existing model architecture. With the help of these improvements, acceptable predicted trajectories were successfully obtained. Experiments on public datasets have demonstrated the algorithm's effectiveness and achieved acceptable results.

Keywords: deep learning, graph convolutional network, attention mechanism, LSTM

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Authors: B. J. Babalola, M. B. Shongwe

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Spark Plasma Sintering technique is a novel processing method that produces limited grain growth and highly dense variety of materials; alloys, superalloys, and carbides just to mention a few. However, initial particle size and spark plasma sintering parameters are factors which influence the grain growth and mechanical properties of sintered materials. Ni-Cr alloys are regarded as the most promising alloys for aerospace turbine blades, owing to the fact that they meet the basic requirements of desirable mechanical strength at high temperatures and good resistance to oxidation. The conventional method of producing this alloy often results in excessive grain growth and porosity levels that are detrimental to its mechanical properties. The effect of sintering temperature was evaluated on the microstructure and mechanical properties of the nanostructured Ni-17Cr alloy. Nickel and chromium powder were milled using high energy ball milling independently for 30 hours, milling speed of 400 revs/min and ball to powder ratio (BPR) of 10:1. The milled powders were mixed in the composition of Nickel having 83 wt % and chromium, 17 wt %. This was sintered at varied temperatures from 800°C, 900°C, 1000°C, 1100°C and 1200°C. The structural characteristics such as porosity, grain size, fracture surface and hardness were analyzed by scan electron microscopy and X-ray diffraction, Archimedes densitometry, micro-hardness tester. The corresponding results indicated an increase in the densification and hardness property of the alloy as the temperature increases. The residual porosity of the alloy reduces with respect to the sintering temperature and in contrast, the grain size was enhanced. The study of the mechanical properties, including hardness, densification shows that optimum properties were obtained for the sintering temperature of 1100°C. The advantages of high sinterability of Ni-17Cr alloy using milled powders and microstructural details were discussed.

Keywords: densification, grain growth, milling, nanostructured materials, sintering temperature

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Authors: Aniela Pop, Ianina Birsan, Corina Orha, Rodica Pode, Florica Manea

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Carbon nanofiber-epoxy composite electrode has been investigated through voltammetric and amperometric techniques in order to detect parabens from aqueous solutions. The occurrence into environment as emerging pollutants of these preservative compounds has been extensively studied in the last decades, and consequently, a rapid and reliable method for their quantitative quantification is required. In this study, methylparaben (MP) and propylparaben (PP) were chosen as representatives for paraben class. The individual electrochemical detection of each paraben has been successfully performed. Their electrochemical oxidation occurred at the same potential value. Their simultaneous quantification should be assessed electrochemically only as general index of paraben class as a cumulative signal corresponding to both MP and PP from solution. The influence of pH on the electrochemical signal was studied. pH ranged between 1.3 and 9.0 allowed shifting the detection potential value to smaller value, which is very desired for the electroanalysis. Also, the signal is better-defined and higher sensitivity is achieved. Differential-pulsed voltammetry and square-wave voltammetry were exploited under the optimum pH conditions to improve the electroanalytical performance for the paraben detection. Also, the operation conditions were selected, i.e., the step potential, modulation amplitude and the frequency. Chronomaprometry application as the easiest electrochemical detection method led to worse sensitivity, probably due to a possible fouling effect of the electrode surface. The best electroanalytical performance was achieved by pulsed voltammetric technique but the selection of the electrochemical technique is related to the concrete practical application. A good reproducibility of the voltammetric-based method using carbon nanofiber-epoxy composite electrode was determined and no interference effect was found for the cation and anion species that are common in the water matrix. Besides these characteristics, the long life-time of the electrode give to carbon nanofiber-epoxy composite electrode a great potential for practical applications.

Keywords: carbon nanofiber-epoxy composite electrode, electroanalysis, methylparaben, propylparaben

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Authors: Sarthak Karki, Haribansha Timalsina

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Kanchan Arsenic Filter is an economical low cost and termed the most efficient arsenic removal filter system in South Asian countries such as Nepal. But when the effluent quality was evaluated, it was seen to possess a lower removal rate of arsenite species. In addition to that, greater pathogenic growth and loss in overall efficacy with time due to precipitation of iron sulphates were the further complications. This brings the health issue on the front line as millions of people rely on groundwater sources for general water necessities. With this paper, we analyzed the mechanisms and changes in the efficiency of the extant filter system when integrated with activated laterite and hair column beds, plus an additional charcoal layer for inhibiting pathogen colonies. Hair column have rich keratin protein that binds with arsenic species, and similarly, raw laterite has huge deposits of iron and aluminum, all of these factors helping to remove heavy metal contaminants from water sources. Further study on the commercialized mass production of the new proposed filter and versatility analysis is required.

Keywords: laterite, charcoal, arsenic removal, hair column

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Authors: Faezeh Shalchy

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Concrete is the most used materials in the world. It is also one of the most versatile while complex materials which human have used for construction. However, concrete is weak in tension, over the past thirty years many studies were accomplished to improve the tensile properties of concrete (cement-based materials) using a variety of methods. One of the most successful attempts is to use polymeric fibers in the structure of concrete to obtain a composite with high tensile strength and ductility. Understanding the mechanical behavior of fiber reinforced concrete requires the knowledge of the fiber/matrix interfaces at the small scale. In this study, a combination of numerical simulations and experimental techniques have been used to study the nano structure of fiber/matrix interfaces. A new model for calcium-silicate-hydrate (C-S-H)/fiber interfaces is proposed based on Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX) analysis. The adhesion energy between the C-S-H gel and 2 different polymeric fibers (polyvinyl alcohol and polypropylene) was numerically studied at the atomistic level since adhesion is one of the key factors in the design of fiber reinforced composites. The mechanisms of adhesion as a function of the nano structure of fiber/matrix interfaces are also studied and discussed.

Keywords: fiber-reinforced concrete, adhesion, molecular modeling

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Authors: V. Pérez-Herranz, M. Pinel, E. M. Ortega, M. García-Gabaldón

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In the present work, Electrochemical Impedance Spectrocopy (EIS) is applied to study the transport of different metal cations through a cation-exchange membrane. This technique enables the identification of the ionic-transport characteristics and to distinguish between different transport mechanisms occurring at different current density ranges. The impedance spectra are dependent on the applied dc current density, on the type of cation and on the concentration. When the applied dc current density increases, the diameter of the impedance spectra loops increases because all the components of membrane system resistance increase. The diameter of the impedance plots decreases in the order of Na(I), Ni(II) and Cr(III) due to the increased interactions between the negatively charged sulfonic groups of the membrane and the cations with greater charge. Nyquist plots are shifted towards lower values of the real impedance, and its diameter decreases with the increase of concentration due to the decrease of the solution resistance.

Keywords: ion-exchange membranes, Electrochemical Impedance Spectrocopy, multivalent metal cations, membrane system

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Authors: Hami Ashraf, Farid Kosari

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Graft-versus-host disease (GvHD) is a common complication of allogeneic hematopoietic stem cell transplantation that can lead to significant morbidity and mortality. Histopathological examination of affected tissues is an essential tool for diagnosing and grading GvHD in animal models, which are used to study disease mechanisms and evaluate new therapies. In this systematic review, we identified and analyzed original research articles in PubMed, Scopus, Web of Science, and Google Scholar that described grading systems for GvHD in animal models based on histopathological features. We found that several grading systems have been developed, which vary in the tissues and criteria they assess, the severity scoring scales they use, and the level of detail they provide. Skin, liver, and gut are the most commonly evaluated tissues, but lung and thymus are also included in some systems. Our analysis highlights the need for standardized criteria and consistent use of grading systems to enable comparisons between studies and facilitate the translation of preclinical findings to clinical practice.

Keywords: graft-versus-host disease, GvHD, animal model, histopathology, grading system

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Authors: Pavel Zabrodin

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The drawback of magnesium alloys is poor plasticity, which complicates the forming. Effective way of improving the properties of the cast magnesium alloy AZ31 (3 wt. % Al, 0.8 wt. % Zn, 0.2 wt. % Mn)) is to combine hot extrusion at 350°C and equal-channel angular pressing (ECAP) at 180°C. Because of reduced grain sizes, changes in the nature of the grain boundaries, and enhancement of a texture that favors basal dislocation glide, after this kind of processing, increase yield stress and ductility. For study of the effect of microstructure on the mechanisms for plastic deformation, there is some interest in investigating the mechanical properties of the ultrafinegrained (UFG) Mg alloy at low temperatures, before and after annealing. It found that the amplitude and statistics at the low-temperature jump-like deformation the Mg alloy of dependent on microstructure. Reduction of the average density of dislocations and grain growth during annealing causing a reduction in the amplitude of the jump-like deformation and changes in the distribution of surges in amplitude. It found that the amplitude and statistics at the low-temperature jump-like deformation UFG alloy dependent on temperature of deformation. Plastic deformation of UFG alloy at a temperature of 10 K occurs uniformly - peculiarities is not observed. Increasing of the temperature of deformation from 4,2 to 0,5 K is causing a reduction in the amplitude and increasing the frequency of the jump-like deformation.

Keywords: jump-like deformation, low temperature, plasticity, magnesium alloy

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Authors: Lucia Steenkamp, Chris V. D. Westhuyzen, Kgama Mathiba

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Ambergris, and more specifically its oxidation product (–)-ambrafuran, is a scarce, valuable, and sought-after perfumery ingredient. The material is used as a fixative agent to stabilise perfumes in formulations by reducing the evaporation rate of volatile substances. Ambergris is a metabolic product of the sperm whale (Physeter macrocephatus L.), resulting from intestinal irritation. Chemically, (–)-ambrafuran is produced from the natural product sclareol in eight synthetic steps – in the process using harsh and often toxic chemicals to do so. An overall yield of no more than 76% can be achieved in some routes, but generally, this is lower. A new 'green' route has been developed in our laboratory in which sclareol, extracted from the Clary sage plant, is converted to (–)-ambrafuran in two steps with an overall yield in excess of 80%. The first step uses a microorganism, Hyphozyma roseoniger, to bioconvert sclareol to an intermediate diol using substrate concentrations up to 50g/L. The yield varies between 90 and 67% depending on the substrate concentration used. The purity of the diol product is 95%, and the diol is used without further purification in the next step. The intermediate diol is then cyclodehydrated to the final product (–)-ambrafuran using a zeolite, which is not harmful to the environment and is readily recycled. The yield of the product is 96%, and following a single recrystallization, the purity of the product is > 99.5%. A preliminary LC-MS study of the bioconversion identified several intermediates produced in the fermentation broth under oxygen-restricted conditions. Initially, a short-lived ketone is produced in equilibrium with a more stable pyranol, a key intermediate in the process. The latter is oxidised under Norrish type I cleavage conditions to yield an acetate, which is hydrolysed either chemically or under lipase action to afford the primary fermentation product, an intermediate diol. All the intermediates identified point to the likely CYP450 action as the key enzyme(s) in the mechanism. This invention is an exceptional example of how the power of biocatalysis, combined with a mild, benign chemical step, can be deployed to replace a total chemical synthesis of a specific chiral antipode of a commercially relevant material.

Keywords: ambrafuran, biocatalysis, fragrance, microorganism

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Authors: Reza Tirsadi Librawan, Tara Vergita Rakhma

Abstract:

The increasing demand for energy and concern of global warming are intertwined issues of critical importance. With the pressing needs of clean, efficient and cost-effective energy conversion processes, an alternative clean energy source is needed. Biomass is one of the preferable options because it is clean and renewable. The efficiency for biomass conversion is constrained by the relatively low energy density and high moisture content from biomass. This study based on bio-based resources presents the Biomass Direct Chemical Looping Combustion Process (BDCLC), an alternative process that has a potential to convert biomass in thermal cracking to produce electricity and CO2. The BDCLC process using iron-based oxygen carriers has been developed as a biomass conversion process with in-situ CO2 capture. The BDCLC system cycles oxygen carriers between two reactor, a reducer reactor and combustor reactor in order to convert coal for electric power generation. The reducer reactor features a unique design: a gas-solid counter-current moving bed configuration to achieve the reduction of Fe2O3 particles to a mixture of Fe and FeO while converting the coal into CO2 and steam. The combustor reactor is a fluidized bed that oxidizes the reduced particles back to Fe2O3 with air. The oxidation of iron is an exothermic reaction and the heat can be recovered for electricity generation. The plant design’s objective is to obtain 5 MW of electricity with the design of the reactor in 900 °C, 2 ATM for the reducer and 1200 °C, 16 ATM for the combustor. We conduct process simulation and analysis to illustrate the individual reactor performance and the overall mass and energy management scheme of BDCLC process that developed by Aspen Plus software. Process simulation is then performed based on the reactor performance data obtained in multistage model.

Keywords: biomass, CO2 capture, direct chemical looping combustion, power generation

Procedia PDF Downloads 504

Authors: A. Ojha, Y. K. Gupta

Abstract:

Organophosphate (OP) pesticides are among the most widely used synthetic chemicals for controlling a wide variety of pests throughout the world. Chlorpyrifos (CPF), methyl parathion (MPT), and malathion (MLT) are among the most extensively used OP pesticides in India. DNA strand breaks and DNA-protein crosslinks (DPC) are toxic lesions associated with the mechanisms of toxicity of genotoxic compounds. In the present study, we have examined the potential of CPF, MPT, and MLT individually and in combination, to cause DNA strand breakage and DPC formation. Peripheral blood lymphocytes of rat were exposed to 1/4 and 1/10 LC50 dose of CPF, MPT, and MLT for 2, 4, 8, and 12h. The DNA strand break was measured by the comet assay and expressed as DNA damage index while DPC estimation was done by fluorescence emission. There was significantly marked increase in DNA damage and DNA-protein crosslink formation in time and dose dependent manner. It was also observed that MPT caused the highest level of DNA damage as compared to other studied OP compounds. Thus, from present study, we can conclude that studied pesticides have genotoxic potential. The pesticides mixture does not potentiate the toxicity of each other. Nonetheless, additional in vivo data are required before a definitive conclusion can be drawn regarding hazard prediction to humans.

Keywords: organophosphate, pesticides, DNA damage, DNA protein crosslink, genotoxic

Procedia PDF Downloads 353

Authors: Li Qiaoming

Abstract:

The outbreak of Coronavirus disease 2019 (COVID-19) in early 2020 brought new opportunities to the development of the digital creative industry in China. Based on the realistic foundation of the development of the digital creative industry in China, an analysis was conducted on the mechanism of action of the pandemic on this industry from both sides of supply and demand by sorting out its concept, connotation, and related theories. To be specific, the demand side experienced changes due to the changes in the consumption habits of residents, the sharp increase in gross domestic time (GDT), the satisfaction of the psychological needs of users, search for substitutes for offline consumption, and other factors. An analysis was carried out on the mechanism of action of the pandemic on the digital creative industry from the production link, supply subjects, product characteristics, and transmission link of the supply side. Then, a detailed discussion was held on the manifestation forms of the impact of the pandemic from the dimensions of time and space. Finally, this paper discussed the main development focuses of the digital creative industry in the post-pandemic era from the aspects of the government, industries, and enterprises.

Keywords: COVID-19, demand and supply relationship, digital creative industries, industry shocks

Procedia PDF Downloads 148