Search results for: oxygen reduction reaction (ORR)

Authors: Abhishek Srivastava, Jeevesh Nandan, Manish Kumar

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The study was taken to analyse the alternative source of traffic system for effective and more convenient traffic flow by reducing points of conflicts as well as angle of conflict and keeping in view to minimize the problem of unnecessarily long waiting time, delays, congestion, traffic jam and geometric delays due to intersection between circular and straight lanes. It is a twin kidney-spine type structure system with special allowance for Highway users for quicker passes. Thus reduction in number and intensity of accidents, significance reduction in traffic jam, conservation of valuable time.

Keywords: traffic system, collision reduction of vehicles, smooth flow of vehicles, traffic jam

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Authors: Ajish K. Abraham

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Hearing aid is the most fundamental technology employed towards rehabilitation of persons with sensory neural hearing impairment. Hearing in noise is still a matter of major concern for many hearing aid users and thus continues to be a challenging issue for the hearing aid designers. Several techniques are being currently used to enhance the speech at the hearing aid output. Most of these techniques, when implemented, result in reduction of intelligibility of the speech signal. Thus the dissatisfaction of the hearing aid user towards comprehending the desired speech amidst noise is prevailing. Multichannel Wiener Filter is widely implemented in binaural hearing aid technology for noise reduction. In this study, Wiener filter based noise reduction approach is experimented for a single microphone based hearing aid set up. This method checks the status of the input speech signal in each frequency band and then selects the relevant noise reduction procedure. Results showed that the Wiener filter based algorithm is capable of enhancing speech even when the input acoustic signal has a very low Signal to Noise Ratio (SNR). Performance of the algorithm was compared with other similar algorithms on the basis of improvement in intelligibility and SNR of the output, at different SNR levels of the input speech. Wiener filter based algorithm provided significant improvement in SNR and intelligibility compared to other techniques.

Keywords: hearing aid output speech, noise reduction, SNR improvement, Wiener filter, speech enhancement

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Authors: Yetti Marlida, Syukri Arif, Nadirman Haska

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Recently, alcohol fuels have been produced on industrial scales by fermentation of sugars derived from wheat, corn, sugar beets, sugar cane etc. The enzymatic hydrolysis of cellulosic materials to produce fermentable sugars has an enormous potential in meeting global bioenergy demand through the biorefinery concept, since agri-food processes generate millions of tones of waste each year (Xeros and Christakopoulos 2009) such as sugar cane baggase , wheat straw, rice straw, corn cob, and oil palm trunk. In fact oil palm trunk is one of the most abundant lignocellulosic wastes by-products worldwide especially come from Malaysia, Indonesia and Nigeria and provides an alternative substrate to produce useful chemicals such as bioethanol. Usually, from the ages 3 years to 25 years, is the economical life of oil palm and after that, it is cut for replantation. The size of trunk usually is 15-18 meters in length and 46-60 centimeters in diameter. The trunk after cutting is agricultural waste causing problem in elimination but due to the trunk contains about 42% cellulose, 34.4%hemicellulose, 17.1% lignin and 7.3% other compounds,these agricultural wastes could make value added products (Pumiput, 2006).This research was production of bioethanol from oil palm trunk via saccharafication by cocktail carbohydrases enzymes. Enzymatic saccharification of acid treated oil palm trunk was carried out in reaction mixture containing 40 g treated oil palm trunk in 200 ml 0.1 M citrate buffer pH 4.8 with 500 unit/kg amylase for treatment A: Treatment B: Treatment A + 500 unit/kg cellulose; C: treatment B + 500 unit/kgg xylanase: D: treatment D + 500 unit/kg ligninase and E: OPT without treated + 500 unit/kg amylase + 500 unit/kg cellulose + 500 unit/kg xylanase + 500 unit/kg ligninase. The reaction mixture was incubated on a water bath rotary shaker adjusted to 600C and 75 rpm. The samples were withdraw at intervals 12 and 24, 36, 48,60, and 72 hr. For bioethanol production in biofermentor of 5L the hydrolysis product were inoculated a loop of Saccharomyces cerevisiae and then incubated at 34 0C under static conditions. Samples are withdraw after 12, 24, 36, 48 and 72 hr for bioethanol and residual glucose. The results of the enzymatic hidrolysis (Figure1) showed that the treatment B (OPT hydrolyzed with amylase and cellulase) have optimum condition for glucose production, where was both of enzymes can be degraded OPT perfectly. The same results also reported by Primarini et al., (2012) reported the optimum conditions the hydrolysis of OPT was at concentration of 25% (w /v) with 0.3% (w/v) amylase, 0.6% (w /v) glucoamylase and 4% (w/v) cellulase. In the Figure 2 showed that optimum bioethanol produced at 48 hr after incubation,if time increased the biothanol decreased. According Roukas (1996), a decrease in the concentration of ethanol occur at excess glucose as substrate and product inhibition effects. Substrate concentration is too high reduces the amount of dissolved oxygen, although in very small amounts, oxygen is still needed in the fermentation by Saccaromyces cerevisiae to keep life in high cell concentrations (Nowak 2000, Tao et al. 2005). The results of the research can be conluded that the optimum enzymatic hydrolysis occured when the OPT added with amylase and cellulase and optimum bioethanol produced at 48 hr incubation using Saccharomyses cerevicea whereas 18.08 % bioethanol produced from glucose conversion. This work was funded by Directorate General of Higher Education (DGHE), Ministry of Education and Culture, contract no.245/SP2H/DIT.LimtabMas/II/2013

Keywords: oil palm trunk, enzymatic hydrolysis, saccharification

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Authors: Lenka Markovičová, Viera Zatkalíková, Tomasz Garbacz

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The development of composite materials and the related design and manufacturing technologies is one of the most important advances in the history of materials. Composites are multifunctional materials having unprecedented mechanical and physical properties that can be tailored to meet the requirements of a particular application. Some composites also exhibit great resistance to high-temperature corrosion, oxidation, and wear. Polymers are widely used indoors and outdoors, therefore they are exposed to a chemical environment which may include atmospheric oxygen, acidic fumes, acidic rain, moisture heat and thermal shock, ultra-violet light, high energy radiation, etc. Different polymers are affected differently by these factors even though the amorphous polymers are more sensitive. Ageing is also important and it is defined as the process of deterioration of engineering materials resulting from the combined effects of atmospheric radiation, heat, oxygen, water, micro-organisms and other atmospheric factors.

Keywords: composites with glass fibers, mechanical properties, polyamides, UV degradation

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Authors: Elena Maria Scalisi

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The increasing production and the use of TiO₂ nanoparticles (NPs) have inevitably led to their release into the environment, thereby posing a threat to organisms and also for human. Human exposure to TiO₂-NPs may occur during both manufacturing and use. TiO₂-NPs are common in consumer products for dermal application, toothpaste, food colorants, and nutritional supplements, then oral exposure may occur during use of such products. Into the body, TiO₂-NPs thanks to their small size (<100 nm), can, through testicular blood barrier inducing effect on testis and then on male reproductive health. The nanoscale size of TiO₂ increase the surface-to-volume ratio making them more reactive in a cell, then TiO₂ NPs increase their ability to produce reactive oxygen species (ROS). In male germ cells, ROS may have important implications in maintaining the normal functions of mature spermatozoa at physiological levels, moreover, in spermatozoa they are important signaling molecules for their hyperactivation and acrosome reaction. Nevertheless, an excess of ROS by external inputs such as NPs can increased the oxidative stress (OS), which results in damage DNA and apoptosis. The aim of our study has been investigate the impact of TiO₂ NPs on human spermatozoa, evaluating DNA damage and the expression of proteins involved in cell stress. According WHO guidelines 2021, we have exposed human spermatozoa in vitro to TiO₂ NP at concentrations 50 ppm, 100 ppm, 250 ppm, and 500 ppm for 1 hour (at 37°C and CO₂ at 5%). DNA damage was evaluated by Sperm Chromatin Dispersion Test (SCD) and TUNEL assay; moreover, we have evaluated the expression of biomarkers of oxidative stress like Heat Shock Protein 70 (HSP70) and Metallothioneins (MTs). Also, sperm parameters as motility viability have been evaluated. Our results not report a significant reduction in motility of spermatozoa at the end of the exposure. On the contrary, the progressive motility was increased at the highest concentration (500 ppm) and was statistically significant compared to control (p <0.05). Also, viability was not changed by exposure to TiO₂-NPs (p <0.05). However, increased DNA damage was observed at all concentrations, and the TUNEL assay highlighted the presence of single strand breaks in the DNA. The spermatozoa responded to the presence of TiO₂-NPs with the expression of Hsp70, which have a protective function because they allow the maintenance of cellular homeostasis in stressful/ lethal conditions. A positivity for MTs was observed mainly for the concentration of 4 mg/L. Although the biological and physiological function of the metallothionein (MTs) in the male genital organs is unclear, our results highlighted that the MTs expressed by spermatozoa maintain their biological role of detoxification from metals. Our results can give additional information to the data in the literature on the toxicity of TiO₂-NPs and reproduction.

Keywords: human spermatozoa, DNA damage, TiO₂-NPs, biomarkers

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Authors: Nur Atirah Hasmi, Nadia Nisha Musa, Hasnun Nita Ismail, Zulfadli Mahfodz

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The effect of water quality parameters on the abundance of aquatic insects has been studied in Batu Berangkai, Dipang, Kuala Woh and Lata Kinjang Rivers, Perak, northern peninsular Malaysia. The focuses are to compare the abundance of aquatic insects in each sampling areas and to investigate the physical and chemical factors (water temperature, depth of water, canopy, water velocity, pH value, and dissolved oxygen) on the abundance of aquatic insects. The samples and data were collected by using aquatic net and multi-probe parameter. Physical parameters; water velocity, water temperature, depth, canopy cover, and two chemical parameters; pH value and dissolved oxygen have been measured in situ and recorded. A total of 631 individuals classified into 6 orders and 18 families of aquatic insects were identified from four sampling sites. The largest percentage of samples collected is from order Plecoptera 35.8%, followed by Ephemeroptera 32.6%, Trichoptera 17.0%, Hemiptera 8.1%, Coleoptera 4.8%, and the least is Odonata 1.7%. The aquatic insects collected from Dipang River have the highest abundance of 273 individuals from 6 orders and 13 families and the least insects trapped at Lata Kinjang which only have 64 individuals from 5 orders and 6 families. There is significant association between different sampling areas and abundance of aquatic insects (p<0.05). High abundance of aquatic insects was found in higher water temperature, low water velocity, deeper water, low pH, high amount of dissolved oxygen, and the area that is not covered by canopy.

Keywords: aquatic insect, physicochemical parameter, river, water quality

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Authors: Enayat Enayati, Reza Behtash

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The purpose of the H2 removal system is to reduce a content of hydrogen and other combustibles in the CO2 feed owing to avoid developing a possible explosive condition in the synthesis. In order to reduce the possibility of forming an explosive gas mixture in the synthesis as much as possible, the hydrogen percent in the fresh CO2, will be removed in hydrogen converter. Therefore the partly compressed CO2/Air mixture is led through Hydrogen converter (Reactor) where the H2, present in the CO2, is reduced by catalytic combustion to values less than 50 ppm (vol). According the following exothermic chemical reaction: 2H2 + O2 → 2H2O + Heat. The catalyst in hydrogen converter consist of platinum on a aluminum oxide carrier. Low catalyst activity maybe due to catalyst poisoning. This will result in an increase of the hydrogen content in the CO2 to the synthesis. It is advised to shut down the plant when the outlet of hydrogen converter increased above 100 ppm, to prevent undesirable gas composition in the plant. Replacement of catalyst will be time exhausting and costly so as to prevent this, we increase the inlet temperature of hydrogen converter according to following Arrhenius' equation: K=K0e (-E_a/RT) K is rate constant of a chemical reaction where K0 is the pre-exponential factor, E_a is the activation energy, and R is the universal gas constant. Increment of inlet temperature of hydrogen converter caused to increase the rate constant of chemical reaction and so declining the amount of hydrogen from 125 ppm to 70 ppm.

Keywords: catalyst, converter, poisoning, temperature

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Authors: Krittiya Pornmai, Sumaeth Chavadej

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The increasing in global energy demand has affected the climate change caused by the generation of greenhouse gases. Therefore, the objective of this work was to investigate a direct production of synthesis gas from a CO₂-containing natural gas by using gliding arc discharge plasma technology. In this research, the effects of steam reforming, combined steam reforming and partial oxidation, and using multistage gliding arc discharge system on the process performance have been discussed. The simulated natural gas used in this study contains 70% methane, 5% ethane, 5% propane, and 20% carbon dioxide. In comparison with different plasma reforming processes (under their optimum conditions), the steam reforming provides the highest H₂ selectivity resulting from the cracking reaction of steam. In addition, the combined steam reforming and partial oxidation process gives a very high CO production implying that the addition of both oxygen and steam can offer the acceptably highest synthesis gas production. The stage number of plasma reactor plays an important role in the improvement of CO₂ conversion. Moreover, 3 stage number of plasma reactor is considered as an optimum stage number for the reforming of CO₂-containing natural gas with steam and partial oxidation in term of providing low energy consumption as compared with other plasma reforming processes.

Keywords: natural gas, reforming process, gliding arc discharge, plasma technology

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Authors: Kamila Duś-Szachniewicz, Kinga M. Walaszek, Paweł Skiba, Paweł Kołodziej, Piotr Ziółkowski

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Cell adhesion is of fundamental importance in the cell communication, signaling, and motility, and its dysfunction occurs prevalently during cancer progression. The knowledge of the molecular and cellular processes involved in abnormalities in cancer cells adhesion has greatly increased, and it has been focused mainly on cellular adhesion molecules (CAMs) and tumor microenvironment. Unfortunately, most of the data regarding CAMs expression relates to study on cells maintained in standard oxygen condition of 21%, while the emerging evidence suggests that culturing cells in ambient air is far from physiological. In fact, oxygen in human tissues ranges from 1 to 11%. The aim of this study was to compare the effects of physiological lymph node normoxia (5% O2), and hyperoxia (21% O2) on the expression of cellular adhesion molecules of primary diffuse large B-cell lymphoma cells (DLBCL) isolated from 10 lymphoma patients. Quantitative RT-PCR and immunohistochemistry were used to confirm the differential expression of several CAMs, including ICAM, CD83, CD81, CD44, depending on the level of oxygen. Our findings also suggest that DLBCL cells maintained at ambient O2 (21%) exhibit reduced growth rate and migration ability compared to the cells growing in normoxia conditions. Taking into account all the observations, we emphasize the need to identify the optimal human cell culture conditions mimicking the physiological aspects of tumor growth and differentiation.

Keywords: adhesion molecules, diffuse large B-cell lymphoma, physiological normoxia, quantitative RT-PCR

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Authors: Ahmed Yousef A. Al Sultan

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Introduction: The aim of this review is based on clinical research that studies the changes in middle cerebral artery velocity using Transcranial Doppler (TCD) and cerebral oxygen saturation using cerebral oximetry in patients undergoing carotid endarterectomy (CEA) surgery under local anesthesia (LA). Patients with or without neurological symptoms during the surgery are taking a role in this study using triplet method of cerebral oximetry, transcranial doppler and awake test in detecting any cerebral ischemic symptoms. Methods: about one hundred patients took part during their CEA surgeries under local anesthesia, using triple assessment mentioned method, Patients requiring general anesthesia be excluded from analysis. All data were recorded at eight surgery stages separately to serve this study. Results: In total regional cerebral oxygen saturation (rSO2), middle cerebral artery (MCA) velocity, and pulsatility index were significantly decreased during carotid artery clamping step in CEA procedures on the targeted carotid side. With most observed changes in MCA velocity during the study. Discussion: Cerebral oxygen saturation and middle cerebral artery velocity were significantly decreased during clamping step of the procedures on the targeted side. The team with neurological symptoms during the procedures showed higher changes of rSO2 and MCA velocity than the team without neurological symptoms. Cerebral rSO2 and MCA velocity significantly increased directly after de-clamping of the internal carotid artery on the affected side.

Keywords: awake testing, carotid endarterectomy, cerebral oximetry, Tanscranial Doppler

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Authors: Sarra Boughaba

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The α-aminophosphonates have received considerable attention in organic and medicinal chemistry because of their structural resemblance with α-amino acids. They are used as antitumor agents, anti-inflammatory and antibiotics. As a result, a number of procedures have been developed for their synthesis. However, many of these methods suffer from some disadvantages such as long reaction times, environmental pollution caused by utilization of organic solvents, and expensive catalyst. On the other hand, thiazole components, particularly 2-aminothiazole is an important class of heterocyclic compounds. They appear in the structure of natural products and biologically actives compounds, thiamine (vitamin-B), and some antibiotics drugs (penicillin, micrococcin). In the past few years, heteropolyacids have received great attention as environmentally benign catalysts for organic synthetic processes, they possess unique physicochemical properties, such as super-acidity, high thermal and chemical stability, ability to accept and release electrons and high proton mobility, and the possibility of varying their acidity and oxidizing potential. In this study, an efficient and eco-friendly process has been developed for the synthesis of α-aminophosphonates containing aminothiazole moiety via Kabachnik-Field reaction catalyzed by H₆P₂W₁₈O₆₂.14H₂O as reusable catalyst, by condensation of aromatic aldehydes, 2-aminothiazole and triethylphosphite under free conditions. The X-ray crystallographic data of obtained compounds were provided. The main advantages of our protocol include the absence of solvent in the reaction, easy work-up, short reaction time, atom-economy and reusability of catalyst without significant loss of its activity.

Keywords: aminophosphonates, green synthesis, H₆P₂W₁₈O₆₂.14H₂O catalyst, x-ray study

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Authors: Nils Mueller, Gregor Herz, Erik Reichelt, Matthias Jahn

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In the context of climate change, the reduction of greenhouse gas emissions in all economic sectors is considered to be an important factor in order to meet the demands of a sustainable energy system. The steel industry as one of the large industrial CO₂ emitters is currently highly dependent on fossil resources. In order to reduce coke consumption and thereby CO₂ emissions while still being able to further utilize existing blast furnaces, the possibility of including a direct reduction process (DRP) into a fully integrated steel mill was investigated. Therefore, a blast furnace model, derived from literature data and implemented in Aspen Plus, was used to analyze the impact of DRI in the blast furnace process. Furthermore, a state-of-the-art DRP was modeled to investigate the possibility of substituting the reducing agent natural gas with hydrogen. A sensitivity analysis was carried out in order to find the boundary percentage of hydrogen as a reducing agent without penalty to the DRI quality. Lastly, the two modeled process steps were combined to form a route of producing pig iron. By varying boundary conditions of the DRP while recording the CO₂ emissions of the two process steps, the overall potential for the reduction of CO₂ emissions was estimated. Within the simulated range, a maximum reduction of CO₂ emissions of 23.5% relative to typical emissions of a blast furnace could be determined.

Keywords: blast furnace, CO₂ mitigation, DRI, hydrogen

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Authors: Aditi Taunk, George Iskander, Kitty Ka Kit Ho, Mark Willcox, Naresh Kumar

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Bacterial infections on biomaterial implants and medical devices accounts for 60-70% of all hospital acquired infections (HAIs). Treatment or removal of these infected devices results in high patient mortality and morbidity along with increased hospital expenses. In addition, with no effective strategies currently available and rapid development of antibacterial resistance has made device-related infections extremely difficult to treat. Therefore, in this project we have developed biomaterial surfaces using antibacterial compounds that inhibit biofilm formation by interfering with the bacterial communication mechanism known as quorum sensing (QS). This study focuses on covalent attachment of potent quorum sensing (QS) inhibiting compounds, halogenated furanones (FUs) and dihydropyrrol-2-ones (DHPs), onto glass surfaces. The FUs were attached by photoactivating the azide groups on the surface, and the acid functionalized DHPs were immobilized on amine surface via EDC/NHS coupling. The modified surfaces were tested in vitro against pathogenic organisms such as Staphylococcus aureus and Pseudomonas aeruginosa using confocal laser scanning microscopy (CLSM). Successful attachment of compounds on the substrates was confirmed by X-ray photoelectron spectroscopy (XPS) and contact angle measurements. The antibacterial efficacy was assessed, and significant reduction in bacterial adhesion and biofilm formation was observed on the FU and DHP coated surfaces. The activity of the coating was dependent upon the type of substituent present on the phenyl group of the DHP compound. For example, the ortho-fluorophenyl DHP (DHP-2) exhibited 79% reduction in bacterial adhesion against S. aureus and para-fluorophenyl DHP (DHP-3) exhibited 70% reduction against P. aeruginosa. The results were found to be comparable to DHP coated surfaces prepared in earlier study via Michael addition reaction. FUs and DHPs were able to retain their in vitro antibacterial efficacy after covalent attachment via azide chemistry. This approach is a promising strategy to develop efficient antibacterial biomaterials to reduce device related infections.

Keywords: antibacterial biomaterials, biomedical device-related infections, quorum sensing, surface functionalization

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Authors: Abdelmahmod Saad

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In this study two amino acids were chosen (DL.alanine,DL.serine) to determine their effect on dissociation of S2O8-2 ino. As the reaction was very slow, Ag+ ino was used as a catalyst. The kinetics measurement showed that the reactions in both cases were found in the first order with respect to S2O8-2, half order with respect to Ag+ and zero order with respect to substrates. Mechanisms were proposed for these reactions according to the determined orders. The energy of activation (AE) was determined for each reaction, and was found to by 30.50 k JmoI-1 in case of DL. Serine and 24.40 k JmoI-1 in case of DL.alanine.

Keywords: mechanism, oxidation, amino acids, peroxodisulphate

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Authors: Seyed Mahdi Rafiaei

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In this investigation, firstly Eu3+ doped YVO4 phosphor was synthesized using solid-state method. Then silica was coated on the surface of particles via sol-gel method. To study the influence of SiO2 addition on microstructure and photoluminescence characteristics of YVO4:4% Eu3+ phosphor materials, we employed X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), High-Resolution Transmitted Electron Microscope (HRTEM), Focused Ion Beam (FIB), Brunauer Emmett Teller (BET), Inductively coupled plasma (ICP), Electron Spin Resonance (ESR) and Photoluminescence (PL) equipments. The XPS characterization confirmed the formation of Y–O–Si and V-O-Si bondings between YVO4:Eu3+ phosphor particle and SiO2 coating. In addition, it was found that although the amounts of added SiO2 were not remarkable, but it resulted in enhancement of emission intensity of the phosphors. Finally by employing ESR analysis, it was shown that surface oxygen vacancies, result in reduction of V5+ to the lower valence state of V4+.

Keywords: solid state, sol-gel, silica, coating, photoluminescence

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Authors: P. Singh, R. M. Banik

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Artificial neural network (ANN) was employed to optimize assay parameters viz., time, temperature, pH of reaction mixture, enzyme volume and substrate concentration of L-glutaminase from Bacillus cereus MTCC 1305. ANN model showed high value of coefficient of determination (0.9999), low value of root mean square error (0.6697) and low value of absolute average deviation. A multilayer perceptron neural network trained with an error back-propagation algorithm was incorporated for developing a predictive model and its topology was obtained as 5-3-1 after applying Levenberg Marquardt (LM) training algorithm. The predicted activity of L-glutaminase was obtained as 633.7349 U/l by considering optimum assay parameters, viz., pH of reaction mixture (7.5), reaction time (20 minutes), incubation temperature (35˚C), substrate concentration (40mM), and enzyme volume (0.5ml). The predicted data was verified by running experiment at simulated optimum assay condition and activity was obtained as 634.00 U/l. The application of ANN model for optimization of assay conditions improved the activity of L-glutaminase by 1.499 fold.

Keywords: Bacillus cereus, L-glutaminase, assay parameters, artificial neural network

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Authors: Simone Galati, Adriano Troia

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Ultrasound (US) is widely used in medical field for a variety diagnostic techniques but, in recent years, it has also been creating great interest for therapeutic aims. Regarding drug delivery, the use of US as an activation source provides better spatial delivery confinement and limits the undesired side effects. However, at present there is no complete characterization at a fundamental level of the different signals produced by sono-activated nanocarriers. Therefore, the aim of this study is to obtain a metrological characterization of the cavitation phenomena induced by US through three parallel investigation approaches. US was focused into a channel of a customized phantom in which a solution with oxygen-loaded nanodroplets (OLNDs) was led to flow and the cavitation activity was monitored. Both quantitative and qualitative real-time analysis were performed giving information about the dynamics of bubble formation, oscillation and final implosion with respect to the working acoustic pressure and the type of nanodroplets, compared with pure water. From this analysis a possible interpretation of the observed results is proposed.

Keywords: cavitation, drug delivery, nanodroplets, ultra-sound

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Authors: Panrapee Suttiwan, Rewadee Watakakosol Arunya Tuicomepee, Sakkaphat T. Ngamake

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Alcohol consumption ranks among the top six of health-risk behaviors that lead to disability and death among Thai teenagers. Underage drinkers have higher health risks than their non-drinking peers do. This study, therefore, aimed to explore salient beliefs of Thai teenagers with alcohol reduction and cessation based on the Theory of Planned Behaviour theoretical framework. Participants were 225 high-school and vocational school students, most of whom (60.9%) consumed alcohol almost daily (5-6 times / week), and one-third of whom (33.8%) reported habitual moderate drink. The average age was 16.5 (SD = 0.9), and the average age of the first use of alcohol was 13.7 (SD = 2.2). Instrument was an open-ended questionnaire that elicited beliefs about having alcohol reduction / cessation in the past 12 months. Findings revealed salient benefit beliefs of alcohol reduction / cessation among the teens such as improved physical and mental health, accident and violence avoidance, less sexual risks, money and time saving, better academic performance, and improved relationships. In contrast, the teens identified several disadvantage beliefs such as deteriorating health, social awkwardness, lack of little fun, excitement, and experience, physical uneasiness, stress, and lack of self-confidence. Salient normative groups for alcohol reduction / cessation included parents, elder relatives, siblings, close friends, teachers, boy / girlfriends, and seniors / juniors at school. Situations influencing alcohol reduction / cessation included quarrels with boy / girlfriends, family conflicts, peer pressure, partying and socializing, festive holidays and anniversary celebration, and visiting entertainment places, etc. This study provides empirical evidence that help to identify normative attitudes towards alcohol reduction / cessation and may thus be an important knowledge for public health campaigns seeking to reduce alcohol consumption in this population.

Keywords: alcohol consumption reduction, cessation, salient belief, Thai teenagers

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Authors: Alcardo Alex Barakabitze, Tan Xiaoheng

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Orthogonal Frequency Division Multiplexing (OFDM) is a special case of Multi-Carrier Modulation (MCM) technique which transmits a stream of data over a number of lower data rate subcarriers. OFDM splits the total transmission bandwidth into a number of orthogonal and non-overlapping subcarriers and transmit the collection of bits called symbols in parallel using these subcarriers. This paper explores the Peak to Average Power Reduction (PAPR) using the Partial Transmit Sequence technique. We provide the distribution analysis and the basics of OFDM signals and then show how the PAPR increases as the number of subcarriers increases. We provide the performance analysis of CCDF and PAPR expressed in decibels through MATLAB simulations. The simulation results show that, in PTS technique, the performance of PAPR reduction in OFDM systems improves significantly as the number of sub-blocks increases. However, by keeping the same number of sub-blocks variation, oversampling factor and the number of OFDM blocks’ iteration for generating the CCDF, the OFDM systems with 128 subcarriers have an improved performance in PAPR reduction compared to OFDM systems with 256, 512 or >512 subcarriers.

Keywords: OFDM, peak to average power reduction (PAPR), bit error rate (BER), subcarriers, wireless communications

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Authors: Ruttayaporn Ngasaman, Saowakon Indouang, Usa Chethanond

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Leptospirosis is a public health concern zoonosis in Thailand. Human and animals are often infected by contact with contaminated water. The infected animals play an important role in leptospira infection for both human and other hosts via urine. In humans, it can cause a wide range of symptoms, some of which may present mild flu-like symptoms including fever, vomiting, and jaundice. Without treatment, Leptospirosis can lead to kidney damage, meningitis, liver failure, respiratory distress, and even death. The prevalence of leptospirosis in stray animals in Thailand is unknown. The aim of this study was to investigate leptospira infection in stray animals including dogs and cats in Songkhla province, Thailand. Total of 434 blood samples were collected from 370 stray dogs and 64 stray cats during the population control program from 2014 to 2018. Screening test using latex agglutination for the detection of antibodies against Leptospira interrogans in serum samples shows 29.26% (127/434) positive. There were 120 positive samples of stray dogs and 7 positive samples of stray cats. Detection by polymerase chain reaction specific to LipL32 gene of Leptospira interrogans showed 1.61% (7/434) positive. Stray cats (5/64) show higher prevalence than stray dogs (2/370). Although active infection was low detected, but seroprevalence was high. This result indicated that stray animals were not active infection during sample collection but they use to get infected or in a latent period of infection. They may act as a reservoir for domestic animals and human in which stay in the same environment. In order to prevent and reduce the risk of leptospira infection in a human, stray animals should be done health checking, vaccination, and disease treatment.

Keywords: leptospirosis, stray animals, risk reduction, Thailand

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Authors: Comfort Mokgothu

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This study investigated the relation between processing information and fitness level of active (fit) and sedentary (unfit) children drawn from rural and urban areas in Botswana. It was hypothesized that fit children would display faster simple reaction time (SRT), choice reaction times (CRT) and movement times (SMT). 60, third grade children (7.0 – 9.0 years) were initially selected and based upon fitness testing, 45 participated in the study (15 each of fit urban, unfit urban, fit rural). All children completed anthropometric measures, skinfold testing and submaximal cycle ergometer testing. The cognitive testing included SRT, CRT, SMT and Choice Movement Time (CMT) and memory sequence length. Results indicated that the rural fit group exhibited faster SMT than the urban fit and unfit groups. For CRT, both fit groups were faster than the unfit group. Collectively, the study shows that the relationship that exists between physical fitness and cognitive function amongst the elderly can tentatively be extended to the pediatric population. Physical fitness could be a factor in the speed at which we process information, including decision making, even in children.

Keywords: decision making, fitness, information processing, reaction time, cognition movement time

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Authors: Fernando Vega, Esmeralda Portillo, Sara Camino, Benito Navarrete, Elena Montavez

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The European Union aims at strongly reducing their CO₂ emissions from energy and industrial sector by 2030. The energy sector contributes with more than two-thirds of the CO₂ emission share derived from anthropogenic activities. Although efforts are mainly focused on the use of renewables by energy production sector, carbon capture and storage (CCS) remains as a frontline option to reduce CO₂ emissions from industrial process, particularly from fossil-fuel power plants and cement production. Among the most feasible and near-to-market CCS technologies, namely post-combustion and oxy-combustion, partial oxy-combustion is a novel concept that can potentially reduce the overall energy requirements of the CO₂ capture process. This technology consists in the use of higher oxygen content in the oxidizer that should increase the CO₂ concentration of the flue gas once the fuel is burnt. The CO₂ is then separated from the flue gas downstream by means of a conventional CO₂ chemical absorption process. The production of a higher CO₂ concentrated flue gas should enhance the CO₂ absorption into the solvent, leading to further reductions of the CO₂ separation performance in terms of solvent flow-rate, equipment size, and energy penalty related to the solvent regeneration. This work evaluates a portfolio of CCS technologies applied to fossil-fuel power plants. For this purpose, an economic evaluation methodology was developed in detail to determine the main economical parameters for CO₂ emission removal such as the levelized cost of electricity (LCOE) and the CO₂ captured and avoided costs. ASPEN Plus™ software was used to simulate the main units of power plant and solve the energy and mass balance. Capital and investment costs were determined from the purchased cost of equipment, also engineering costs and project and process contingencies. The annual capital cost and operating and maintenance costs were later obtained. A complete energy balance was performed to determine the net power produced in each case. The baseline case consists of a supercritical 500 MWe coal-fired power plant using anthracite as a fuel without any CO₂ capture system. Four cases were proposed: conventional post-combustion capture, oxy-combustion and partial oxy-combustion using two levels of oxygen-enriched air (40%v/v and 75%v/v). CO₂ chemical absorption process using monoethanolamine (MEA) was used as a CO₂ separation process whereas the O₂ requirement was achieved using a conventional air separation unit (ASU) based on Linde's cryogenic process. Results showed a reduction of 15% of the total investment cost of the CO₂ separation process when partial oxy-combustion was used. Oxygen-enriched air production also reduced almost half the investment costs required for ASU in comparison with oxy-combustion cases. Partial oxy-combustion has a significant impact on the performance of both CO₂ separation and O₂ production technologies, and it can lead to further energy reductions using new developments on both CO₂ and O₂ separation processes.

Keywords: carbon capture, cost methodology, economic evaluation, partial oxy-combustion

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Authors: Mohamed Ahmed Gesraha, Amany Ramadan Ebeid

Abstract:

Aphids are noxious and serious persistent pests in the open fields worldwide. Many authors studied the possibility of aphid control by applying Ladybirds and Lacewings at different releasing rates under open-field conditions. Results clarify that releasing 3rd instar larvae of Coccinella undecimpunctata at the rate of 1 larva:50 aphid was more effective than 1:100 or 1:200 rates for controlling Aphis gossypii population in Okra field; reflecting more than 90% reduction in the aphid population within 15 days. When Chrysoperla carnea 2nd larval instar were releasing at 1:5, 1:10, and 1:20 (predator: aphid), it was noticed that the former rate was the most effective one, inducing 98.93% reduction in aphid population; while the two other rates reflecting less reduction. Additionally, in the case of double releases, the reduction percentage at the 1:5 rate was 99.63%, emphasize that this rate was the most effective one; the other rates induced 97.05 and 95.64% reduction. Generally, a double release was more effective in all tested rates than the single one because of the cumulative existence of the predators in large numbers at the same period of the experiment. It could be concluded that utilizing insect predators (Coccinella undecimpunctata or Chrysoperla carnea) at an early larval stag were faire enough to reduce the aphids’ populations under open fields conditions.

Keywords: releasing predators, lacewings, ladybird, open fields

Procedia PDF Downloads 179

Authors: A. M. Gsiea, J. P. Goss, P. R. Briddon, Ramadan. M. Al-habashi, K. M. Etmimi, Khaled. A. S. Marghani

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Using first-principles methods based on density functional theory and pseudopotentials, we have performed a details study of native defects in ZnO. Native point defects are unlikely to be cause of the unintentional n-type conductivity. Oxygen vacancies, which considered most often been invoked as shallow donors, have high formation energies in n-type ZnO, in edition are a deep donors. Zinc interstitials are shallow donors, with high formation energies in n-type ZnO, and thus unlikely to be responsible on their own for unintentional n-type conductivity under equilibrium conditions, as well as Zn antisites which have higher formation energies than zinc interstitials. Zinc vacancies are deep acceptors with low formation energies for n-type and in which case they will not play role in p-type coductivity of ZnO. Oxygen interstitials are stable in the form of electrically inactive split interstitials as well as deep acceptors at the octahedral interstitial site under n-type conditions. Our results may provide a guide to experimental studies of point defects in ZnO.

Keywords: DFT, native, n-type, ZnO

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Authors: Avinashkumar Karre

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Sulfur recovery unit, most commonly called as Claus process, is very significant gas desulfurization process unit in refinery and gas industries. Explorations of new natural gas fields, refining of high-sulfur crude oils, and recent crude expansion projects are needing capacity expansion of Claus unit for many companies around the world. In refineries, the sulphur recovery units take acid gas from amine regeneration units and sour water strippers, converting hydrogen sulfide to elemental sulfur using the Claus process. The Claus process is hydraulically limited by mass flow rate. Reducing the pressure drop across control valves, flow meters, lines, knock-out drums, and packing improves the capacity. Oxygen enrichment helps improve the capacity by removing nitrogen, this is more commonly done on all capacity expansion projects. Typical upgrades required due to oxygen enrichment are new burners, new refractory in thermal reactor, resizing of 1st condenser, instrumentation changes, and steam/condensate heat integration. Some other capacity expansion options typically considered are tail gas compressor, replacing air blower with higher head, hydrocarbon minimization in the feed, water removal, and ammonia removal. Increased capacity related upgrades in sulfur recovery unit also need changes in the tail gas treatment unit, typical changes include improvement to quench tower duty, packing area upgrades in quench and absorber towers and increased amine circulation flow rates.

Keywords: Claus process, oxygen enrichment, sulfur recovery unit, tail gas treatment unit

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Authors: Ruth Diego, Luis M. Romeo, Antonio Morán

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In the present work, a study of the coupling of a Bioelectrochemical System together with an oxy-combustion boiler is carried out; specifically, it proposes to connect the combustion gas outlet of a boiler with a microbial electrolysis cell (MEC) where the CO2 from the gases are transformed into methane in the cathode chamber, and the oxygen produced in the anode chamber is recirculated to the oxy-combustion boiler. The MEC mainly consists of two electrodes (anode and cathode) immersed in an aqueous electrolyte; these electrodes are separated by a proton exchange membrane (PEM). In this case, the anode is abiotic (where oxygen is produced), and it is at the cathode that an electroactive biofilm is formed with microorganisms that catalyze the CO2 reduction reactions. Real data from an oxy-combustion process in a boiler of around 20 thermal MW have been used for this study and are combined with data obtained on a smaller scale (laboratory-pilot scale) to determine the yields that could be obtained considering the system as environmentally sustainable energy storage. In this way, an attempt is made to integrate a relatively conventional energy production system (oxy-combustion) with a biological system (microbial electrolysis cell), which is a challenge to be addressed in this type of new hybrid scheme. In this way, a novel concept is presented with the basic dimensioning of the necessary equipment and the efficiency of the global process. In this work, it has been calculated that the efficiency of this power-to-gas system based on MEC cells when coupled to industrial processes is of the same order of magnitude as the most promising equivalent routes. The proposed process has two main limitations, the overpotentials in the electrodes that penalize the overall efficiency and the need for storage tanks for the process gases. The results of the calculations carried out in this work show that certain real potentials achieve an acceptable performance. Regarding the tanks, with adequate dimensioning, it is possible to achieve complete autonomy. The proposed system called OxyMES provides energy storage without energetically penalizing the process when compared to an oxy-combustion plant with conventional CO2 capture. According to the results obtained, this system can be applied as a measure to decarbonize an industry, changing the original fuel of the oxy-combustion boiler to the biogas generated in the MEC cell. It could also be used to neutralize CO2 emissions from industry by converting it to methane and then injecting it into the natural gas grid.

Keywords: microbial electrolysis cells, oxy-combustion, co2, power-to-gas

Procedia PDF Downloads 113

Authors: Noé D. Lazos-Gallardo, Sonia E. Ruiz, Federico Valenzuela-Beltran

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A simplified mathematical expression to estimate ductility reduction factors of the displacement spectra corresponding to the soft soil zone of Mexico City is proposed. The aim is to allow a better characterization of the displacement spectra and provide a simple expression to be used in displacement based design (DBD). Emphasis is on the Mexico City Building Code. The study is based on the analysis of single degree of freedom (SDOF) systems with elasto-plastic hysteretic behavior. Several seismic ground motions corresponding to subduction events with magnitudes equal to or greater than 6 and recorded in different stations of Mexico City are used. The proposed expression involves the ratio of elastic and inelastic pseudo-aceleration spectra, and depends on factors such the ductility demand and the vibration period of the structural system. The resulting ductility reduction factors obtained in this study are compared with others existing in the literature, and their advantages and disadvantages are discussed.

Keywords: displacement based design, displacements spectrum, ductility reduction factors, soft soil

Procedia PDF Downloads 178

Authors: Muskan Parmar, Musthafa Ottakam Thotiyl

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The rising need for portable energy sources has led to advancements in direct liquid fuel cells (DLFCs) using various fuels like alcohol, ammonia, hydrazine, and vitamin C. Traditional precious metal catalysts improve reaction speeds but are expensive and prone to poisoning. Our study reveals how non-precious metal organometallic complexes, combined with smartly designed ligands, can significantly boost performance. The key is a unique interaction between the substrate (fuel) and the ligand, which creates a "dragging" effect that enhances reaction rates. By using this approach with a ferricyanide/ferrocyanide half-cell reaction, we developed a vitamin C fuel cell without precious metals. This fuel cell achieves an open circuit voltage of ∼950 mV, a peak power density of ∼97 mW cm⁻², and a peak current density of ∼215 mA cm⁻². Impressively, its performance is about 1.7 times better than traditional precious metal-based DLFCs. This highlights the potential of substrate ligand chemistry in the creation of sustainable DLFCs for efficient energy conversion.

Keywords: molecular electrocatalysts, vitamin C fuel cell, proton charge assembly, ferricyanide half-cell chemistry

Procedia PDF Downloads 28

Authors: S. Y. Park, S. M. Lee, S. H. Lee, K. M. Lim

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In this research analyzed the effects that phase formation reaction change in the grey cast iron makes on characteristics of microstructures, liquidity, and mechanical properties through cooling curve when adding rare earth elements (R.E). This research was analyzed with comparison between the case of not adding the rare earth elements (R.E) into the grey cast iron with the standard composition (as 3.3%C-2.1%Si-0.7%Mn-0.1%S) and the case of adding 0.3% rare earth elements (R.E). The thermal analysis parameters have been drawn through eutectic temperature theoretically calculated, recalescence temperature, and undercooling temperature measured from start of eutectic reaction to end of solidification in the cooling curve obtained by thermal analysis to analyze formation behavior of graphite, and the effects by addition of rare earth elements on this have been reviewed. When adding rare earth elements (R.E), the cause of liquidity slowdown was analyzed trough the solidification starting temperature and change of solidification ending temperature. The strength and hardness have been measured to evaluate the mechanical properties, and the sound tensile strength has been evaluated through quality coefficient after measuring relative hardness and normality degree of tensile strength by calculating theoretical tensile strength and theoretical hardness. The change of Pearlite Inter-lamellar Spacing of matrix microstructure and eutectic cell count of macrostructure was measured to analyze the effects of the rare earth elements on the sound tensile strength. The change of eutectic cell count has been clarified through activation of the eutectic reaction, and the cause of pearlite inter-lamellar spacing clarified through eutectoid reaction temperature.

Keywords: cooling curve, element, grey cast iron, thermal analysis, rare earth element

Procedia PDF Downloads 363

Authors: S. S. Chong, A. R. Abdul Aziz, S. W. Harun, H. Arof

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A miniaturized non-adiabatic silica microfiber is proposed for biological oxygen demand (BOD) ratio chemical oxygen demand (COD) sensing for the first time. BOD and COD are two main parameters to justify quality of wastewater. A ratio, BOD:COD can usually be established between the two analytical methods once COD and BOD value has been gathered. This ratio plays a vital role to determine appropriate strategy in wastewater treatment. A non-adiabatic microfiber sensor was formed by tapering the SMF to generate evanescent field where sensitive to perturbation of sensing medium. Because difference ratio BOD and COD contain in solution, this may induced changes of effective refractive index between microfiber and sensing medium. Attenuation wavelength shift to right with 0.5 nm and 3.5 nm while BOD:COD equal to 0.09 and 0.18 respectively. Significance difference wavelength shift may relate with the biodegradability of analyte. This proposed sensor is compact, reliable and feasible to determine the BOD:COD. Further research and investigation should be proceeded to enhance sensitivity and precision of the sensor for several of wastewater online monitoring.

Keywords: non-adiabatic fiber sensor, environmental sensing, biodegradability, evanescent field

Procedia PDF Downloads 665