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AEO‑7 surfactant is “super toxic” and induces severe cardiac, liver and locomotion damage in zebrafish embryos
No full textBackground: Fatty alcohol polyoxyethylene ether-7 (AEO-7), a non-ionic surfactant, has recently been receiving extensive attention from the ocean pipeline industry for its ability to inhibit corrosion. However, the present lack of information concerning the potential environmental toxicity of AEO-7, especially towards aquatic organisms, is a major impediment to its wider application. Here, we assess potential adverse effects of AEO-7 on zebrafish embryos employing a variety of assays, including (i) a mortality/survival assay which allowed the median lethal concentration (LC₅₀) to be calculated; (ii) a teratogenicity assay on the basis of which the no observed effect concentration (NOEC) was determined; and (iii) specific assays of cardiotoxicity, neurotoxicity (based on locomotion), hematopoietic toxicity (the level of hemoglobin as revealed by o-dianisidine staining) and hepatotoxicity (liver steatosis and yolk retention examined by staining with Oil Red O). Results: AEO-7 caused mortality with a calculated LC₅₀ of 15.35 μg/L, which, according to the U.S. Fish and Wildlife Service (USFWS) Acute Toxicity Rating scale, should be considered “super toxic”. Although at its NOEC (0.8 μg/L), there were no signs of significant teratogenicity, cardiotoxicity, or hemopoiesis toxicity, 3.2 µg/L AEO-7 exerted dramatic detrimental effects on organ development. Conclusion: On the basis of these findings, we recommend that the industrial usage and environmental impact of AEO-7 be re-evaluated and strictly monitored by environmental and public health organizations.Qatar UniversityQatar National Research Fun
Organ-specific toxicity evaluation of stearamidopropyl dimethylamine (SAPDMA) surfactant using zebrafish embryos
No full textSurfactants are widely used in the industry of detergents, household products, and cosmetics. SAPDMA is a cationic surfactant that is used mostly in cosmetics, conditioning agents and has recently gained attention as a corrosion inhibitor in the sea pipelines industry. In this regard, literature concerning the ecotoxicological classification of SAPDMA on aquatic animals is lacking. This study aims to evaluate the potential ecotoxicity of SAPDMA using the aquatic zebrafish embryo model. The potential toxic effects of SAPDMA were assessed by different assays. This includes (i) mortality/survival assay to assess the median lethal concentration (LC₅₀); (ii) teratogenicity assay to assess the no observed effect concentration (NOEC); (iii) organ-specific toxicity assays including cardiotoxicity, neurotoxicity (using locomotion assay), hematopoietic toxicity (hemoglobin synthesis using o-dianisidine staining), hepatotoxicity (liver steatosis and yolk retention using Oil Red O (ORO) stain); (iv) cellular cytotoxicity (mitochondrial membrane potential) by measuring the accumulation of JC-1 dye into mitochondria. Exposure of embryos to SAPDMA caused mortality in a dose-dependent manner with a calculated LC₅₀ of 2.3 mg/L. Thus, based on the LC₅₀ value and according to the Fish and Wildlife Service (FWS) Acute Toxicity Rating Scale, SAPDMA is classified as “moderately toxic”. The No Observed Effect Concentration (NOEC) concerning a set of parameters including scoliosis, changes in body length, yolk, and eye sizes was 0.1 mg/L. At the same NOEC concentration (0.1 mg/L), no organ-specific toxicity was detected in fish treated with SAPDMA, except hepatomegaly with no associated liver dysfunctions. However, higher SAPDMA concentrations (0.8 mg/L) have dramatic effects on zebrafish organ development (eye, heart, and liver development). Our data recommend a re-evaluation of the SAPDMA employment in the industry setting and its strictly monitoring by environmental and public health agencies.Qatar UniversityQatar National Research Fun
Sustainable Management of Organic Wastes in Sharjah, UAE through Co-Composting
No full textDaily human activities and vast green areas produce substantial amounts of organic wastes that end up in landfills with minimal treatment. In addition to the problems associated with landfills, disposal through this method is unsustainable in the long run and does not allow recovering materials from the waste. This paper focuses on the co-composting of different organic wastes produced in The Emirate of Sharjah, United Arab Emirates (UAE), to optimize mixing proportions of three different kinds of wastes—sewage sludge (SS), green waste (GW), and food waste (FW). All three organic wastes were analyzed to determine their chemical composition and the mixing proportions. Ten different mixing proportions as a function of carbon:nitrogen (C:N ratios) were determined and mixed in a NatureMill composter. Compost samples were tested for pH, salinity, conductivity, moisture content, organic matter, organic carbon, phosphorus, total nitrogen, and final C:N ratio after 6 weeks. Results indicate that a period of 5–6 weeks is sufficient for the compost to stabilize. The varying mixing proportions produced a good-quality compost (C:N up to 20:1) with high nutrient content. The study reaffirms that co-composting can be a potential sustainable organic waste management option for the United Arab Emirates.Bee’a
Antibacterial Activities of Selected Pure Compounds Isolated from Gut Bacteria of Animals Living in Polluted Environments
No full textAntibiotic resistance is a global threat to public health, further accelerated by the misuse of antibiotics in humans and animals. Our recent studies have shown that gut bacteria of animals living in polluted environments are a potential source of antibacterials. Gut bacteria of cockroaches, water monitor lizards and the turtle exhibited molecules such as curcumenol, docosanedioic acid, N-acyl-homoserine lactone, L-homotyrosine and Di-rhamnolipids. Using purified compounds, assays were performed to determine their antibacterial properties using serial dilution method, cytotoxic effects using lactate dehydrogenase release, and cell viability using MTT assay. The results revealed that the purified compounds exhibited significant antibacterial activities (p < 0.05) against selected Gram-negative (Pseudomonas aeruginosa) and Gram-positive bacteria (Streptococcus pyogenes) with effective MIC₅₀ and MIC₉₀ at μg concentrations, and with minimal effects on human cells as observed from LDH and MTT assays. These findings are significant and provide a basis for the rational development of therapeutic antibacterials. Future studies are needed to determine in vivo effects of the identified molecules together with their mode of action, which could lead to the development of novel antibacterial(s).FRGS, MalaysiaAmerican University of Sharja
Memory Effect of the Southern Atlantic Subtropical Dipole
No full textThe South Atlantic subtropical dipole is the dominant mode of coupled variability in the South Atlantic, connecting sea level pressure and sea surface temperature. Previous studies have shown its great relevance to the climate conditions over South America and West Africa. We have used several numerical experiments with the Hybrid Coordinate Ocean Model to investigate the effects that an austral winter-spring dipole asserts on the South Atlantic. We explore the interaction between SST anomalies and the formation of the fossilized mixing region, which preserve temperature anomalies underneath the summer mixed layer, until they feed back to SST after the next autumn. It was found that, through this process, there is a memory effect that restores temperature anomalies from an austral winter–spring dipole back to the austral winter of the following year. The dominant mechanisms are the contribution from entrainment and surface net heat flux (NHF). Entrainment is mostly controlled by vertical temperature gradient anomalies, while surface NHF is controlled by interactions of climatological ocean heat loss and anomalies of mixed layer thickness. Our results suggest that the combined effect of entrainment and surface NHF is different in the southwest and northeast dipole regions, leading to differences in both intensity and timing of SST anomalies. Turbulent and nonlinear processes are most important to reduce entrainment in the southwest dipole region and to increase the memory effect asymmetry.São Paulo State Foundation for Research SupportBrazilian Council of Scientific and Technological DevelopmentFoundation for Science and Technolog
Novel Azoles as Antiparasitic Remedies against Brain-Eating Amoebae
No full textBalamuthia mandrillaris and Naegleria fowleri are opportunistic protozoan pathogens capable of producing infection of the central nervous system with more than 95% mortality rate. Previously, we have synthesized several compounds with antiamoebic properties; however, synthesis of compounds that are analogues of clinically used drugs is a highly desirable approach that can lead to effective drug development against these devastating infections. In this regard, compounds belonging to the azole class possess wide range of antimicrobial properties and used clinically. In this study, six novel benzimidazole, indazole, and tetrazole derivatives were synthesized and tested against brain-eating amoebae. These compounds were tested for their amoebicidal and static properties against N. fowleri and B. mandrillaris. Furthermore, the compounds were conjugated with silver nanoparticles and characterized. The synthetic heterocyclic compounds showed up to 72% and 65% amoebicidal activities against N. fowleri and B. mandrillaris respectively, while expressing up to 75% and 70% amoebistatic activities, respectively. Following conjugation with silver nanoparticles, amoebicidal activities of the drugs increased by up to 46 and 36% versus B. mandrillaris and N. fowleri. Minimal effects were observed when the compounds were evaluated against human cells using cytotoxicity assays. In summary, azole compounds exhibited potent activity against N. fowleri and B. mandrillaris. Moreover, conjugation of the azole compounds with silver nanoparticles further augmented the capabilities of the compounds against amoebae.Sunway UniversityPakistan Academy of Science
Localizing-ground Transmitters Using Airborne Antenna Array
No full textA Master of Science thesis in Mechatronics Engineering by Mirghani Moutaman Daffalla entitled, “Localizing-ground Transmitters Using Airborne Antenna Array”, submitted in December 2020. Thesis advisor is Dr. Hasan Mir and thesis co-advisors are Dr. Mamoun Abdel-Hafez and Dr. Nasser Qaddoumi. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).A radio direction finder (RDF) estimates the direction of arrival (DOA) of a radio signal. It receives multiple copies of the signal by a multiple-element antenna array, making use of the characteristics of the received signals. Measurement of the DOA of the received signal is used to localize signals sources, such as radars, mobile phone devices, and RF beacons. This thesis aims to design and implement a direction finding (DF) system that can be integrated on a mobile aerial platform, such as an unmanned aerial vehicle (UAV), in order to localize ground transmitters. General background and concepts about DF systems, RF transmitters, DF applications, and localization have been illustrated and discussed within the thesis. Through the thesis, DF algorithms and techniques have been described and addressed. Comprehensive design approaches and requirements are also discussed in detail. Related hardware is discussed, presented, and simulated and their effects on the system integration is addressed. In order to complement the DF system on a UAV, navigation methods and geographical positioning of the UAV are presented in the thesis.College of EngineeringMultidisciplinary ProgramsMaster of Science in Mechatronics Engineering (MSMTR
Low Frequency Bimorph Cantilever Energy Harvester For Pacemaker Applications
Get PDFA Master of Science thesis in Biomedical Engineering by Abdelrahman Mostafa Khalaf Mostafa entitled, “Low Frequency Bimorph Cantilever Energy Harvester for Pacemaker Applications”, submitted in May 2020. Thesis advisor is Dr. Lufti Albasha. Soft copy is available (Thesis, Approval Signatures, Completion Certificate, and AUS Archives Consent Form).Pacemakers have seen multiple technological advancements but still face multiple issues. The ability to have a leadless and self-powered pacemaker has been always sought after by researchers and scientists. The introduction of flexible electronics has made such an endeavour a realistic and achievable one since it allows pacemakers implantation to take another advantageous shape that allows it to be further useful in the process of implantation without injuring surrounding tissue. Furthermore, energy harvesting systems have developed to a point where a pacemaker can obtain its power from naturally occurring motions and other phenomena inside the body. In this research several techniques and frameworks have been studied to realize a leadless, flexible, self-powered and smart single chamber pacemaker. The main objective of this thesis is to provide a model of a device that consumes minimum amount of power, enabling energy harvesting to be applied. This hence improves the quality of life of patients and deliver acceptable performance as compared to previously made pacemakers.College of EngineeringMultidisciplinary ProgramsMaster of Science in Biomedical Engineering (MSBME
Thermal Conductivities of Choline Chloride-Based Deep Eutectic Solvents and Their Mixtures with Water: Measurement and Estimation
No full textThe thermal conductivities of selected deep eutectic solvents (DESs) were determined using the modified transient plane source (MTPS) method over the temperature range from 295 K to 363 K at atmospheric pressure. The results were found to range from 0.198 W·m−1·K−1 to 0.250 W·m−1·K−1. Various empirical and thermodynamic correlations present in literature, including the group contribution method and mixing correlations, were used to model the thermal conductivities of these DES at different temperatures. The predictions of these correlations were compared and consolidated with the reported experimental values. In addition, the thermal conductivities of DES mixtures with water over a wide range of compositions at 298 K and atmospheric pressure were measured. The standard uncertainty in thermal conductivity was estimated to be less than ± 0.001 W·m−1·K−1 and ± 0.05 K in temperature. The results indicated that DES have significant potential for use as heat transfer fluids
Optimization of p-chart for Processes with Multiple Assignable Causes and Random Shift
No full textA Master of Science thesis in Engineering Systems Management by Emad Aldin Mohammed Abdelkreem Mohammed entitled, “Optimization of P-Chart for Processes with Multiple Assignable Causes and Random Shift”, submitted in May 2020. Thesis advisor is Dr. Mahmoud Awad. Soft copy is available (Thesis, Approval Signatures, Completion Certificate, and AUS Archives Consent Form).Attribute control charts are used extensively in many industries to detect assignable causes for many processes. They are particularly useful in the service industries due to difficulty of evaluating services using variable scale. In addition, several critical-toquality characteristics in manufacturing and service can be combined to determine whether to accept or reject the product. The optimization of fraction non-conforming p-chart has been mainly addressed from either statistical or economic prospective or considering only single assignable cause. In this research, we propose an economicstatistical model that considers the process history of the nonconforming units to design a p-chart for processes with multiple assignable causes. The method is demonstrated using a drinking water bottling case and shows improved results compared to existing methods. When comparing the results of the proposed method with traditional methods, the proposed method is expected to reduce poor quality cost by 0.86% per unit. For a mass production company such as the water bottling company with half a million bottles filled every day, the proposed method is expected to provide significant monetary savings along with improved reputation.College of EngineeringDepartment of Industrial EngineeringMaster of Science in Engineering Systems Management (MSESM