Search results for: pathogens removal

Authors: Soukaina Motia, Nadia El Alami El Hassani, Alassane Diouf, Benachir Bouchikhi, Nezha El Bari

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Parabens are the antimicrobial molecules largely used in cosmetic products as a preservative agent. Among them, the methylparaben (MP) is the most frequently used ingredient in cosmetic preparations. Nevertheless, their potential dangers led to the development of sensible and reliable methods for their determination in environmental samples. Firstly, a sensitive and selective molecular imprinted polymer (MIP) based on screen-printed gold electrode (Au-SPE), assembled on a polymeric layer of carboxylated poly(vinyl-chloride) (PVC-COOH), was developed. After the template removal, the obtained material was able to rebind MP and discriminate it among other interfering species such as glucose, sucrose, and citric acid. The behavior of molecular imprinted sensor was characterized by Cyclic Voltammetry (CV), Differential Pulse Voltammetry (DPV) and Electrochemical Impedance Spectroscopy (EIS) techniques. Then, the biosensor was found to have a linear detection range from 0.1 pg.mL^-1 to 1 ng.mL^-1 and a low limit of detection of 0.12 fg.mL^-1 and 5.18 pg.mL^-1 by DPV and EIS, respectively. For applications, this biosensor was employed to determine MP content in four wastewaters in Meknes city and two cosmetic products (shower gel and shampoo). The operational reproducibility and stability of this biosensor were also studied. Secondly, another MIP biosensor based on tungsten trioxide (WO₃) functionalized by gold nanoparticles (Au-NPs) assembled on a polymeric layer of PVC-COOH was developed. The main goal was to increase the sensitivity of the biosensor. The developed MIP biosensor was successfully applied for the MP determination in wastewater samples and cosmetic products.

Keywords: cosmetic products, methylparaben, molecularly imprinted polymer, wastewater

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Authors: Oranso T. Mahlangi, Bhekie B. Mamba

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The occurrence of trace organic compounds (TOrCs) in water has raised health concerns for living organisms. The majority of TorCs, including pharmaceuticals and volatile organic compounds, are poorly monitored, partly due to the high cost of analysis and less strict water quality guidelines in South Africa. Therefore, the removal of TorCs is important to guarantee safe potable water. In this study, ZnO nanoparticles were fabricated in situ in polyethersulfone (PES) polymer solutions. This was followed by membrane synthesis using the phase inversion technique. Techniques such as FTIR, Raman, SEM, AFM, EDS, and contact angle measurements were used to characterize the membranes for several physicochemical properties. The membranes were then evaluated for their efficiency in treating pharmaceutical wastewater and resistance to organic (sodium alginate) and protein (bovine serum albumin) fouling. EDS micrographs revealed uniform distribution of ZnO nanoparticles within the polymer matrix, while SEM images showed uniform fingerlike structures. The addition of ZnO increased membrane roughness as well as hydrophilicity (which in turn improved water fluxes). The membranes poorly rejected monovalent and divalent salts (< 10%), making them resistant to flux decline due to concentration polarization effects. However, the membranes effectively removed carbamazepine, caffeine, sulfamethoxazole, ibuprofen, and naproxen by over 50%. ZnO PES membranes were resistant to organic and protein fouling compared to the neat membrane. ZnO PES ultrafiltration membranes may provide a solution in the reclamation of wastewater.

Keywords: trace organic compounds, pharmaceuticals, membrane fouling, wastewater reclamation

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Authors: Viktoriia Malinovska, Iryna Kuklina, Katerina Grabicova, Milos Buric, Pavel Kozak

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Personal care products, including organic UV filters, are considered emerging contaminants and their toxic effects have been a concern for the last decades. Sunscreen compounds continually enter the surface waters via sewage water treatment due to incomplete removal and during human recreational and laundry activities. Despite the environmental occurrence of organic UV filters in the freshwater environment, little is known about their impacts on aquatic biota. In this study, environmentally relevant concentrations of 5-Benzoyl-4-hydroxy-2-methoxybenzenesulfonic acid (BP-4, 2.5 µg/L) and 2-Phenylbenzimidazole-5-sulfonic acid (PBSA, 3 µg/L) were used to evaluate the cardiac and locomotor responses of signal crayfish Pacifastacus leniusculus during a short time period. The effects of these compounds were evident in experimental animals. Specimens exposed to both tested compounds exhibited significantly bigger changes in distance moved and time movement than controls. Significant differences in changes in mean heart rate were detected in both PBSA and BP-4 experimental groups compared to control groups. Such behavioral and physiological alterations demonstrate the ecological effects of selected sunscreen compounds during a short time period. Since the evidence of the impacts of sunscreen compounds is scarce, the knowledge of how organic UV filters influence aquatic organisms is of key importance for future research.

Keywords: aquatic pollutants, behavior, freshwaters, heart rate, invertebrate

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Authors: R. Suresh, Pavan Kumar Nimmagadda, Ming Zo Tan, Shane Hart, Sharp Ugwuocha

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Polycrystalline diamond compact (PDC) drill bits are extensively used in the oil and gas industry as well as the mining industry. Industry engineers continually improve upon PDC drill bit designs and hydraulic conditions. Optimized injection nozzles play a key role in improving the drilling performance and efficiency of these ever changing PDC drill bits. In the first part of this study, computational fluid dynamics (CFD) modelling is performed to investigate the hydrodynamic characteristics of drilling fluid flow around the PDC drill bit. An Open-source CFD software – OpenFOAM simulates the flow around the drill bit, based on the field input data. A specifically developed console application integrates the entire CFD process including, domain extraction, meshing, and solving governing equations and post-processing. The results from the OpenFOAM solver are then compared with that of the ANSYS Fluent software. The data from both software programs agree. The second part of the paper describes the parametric study of the PDC drill bit nozzle to determine the effect of parameters such as number of nozzles, nozzle velocity, nozzle radial position and orientations on the flow field characteristics and bit washing patterns. After analyzing a series of nozzle configurations, the best configuration is identified and recommendations are made for modifying the PDC bit design.

Keywords: ANSYS Fluent, computational fluid dynamics, nozzle configuration, OpenFOAM, PDC dill bit

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Authors: Kaniz Roksana, Aluthgun Hewage Shaini, Cheng Zhu

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Lead is environmentally hazardous because it may persist for a long time in soil, water, and air, and it can travel large distances when carried by wind or water. Lead is toxic to many different species of organisms and has the potential to disrupt ecosystem stability. Moreover, lead can contaminate crops and livestock, which can then have an adverse effect on human health. This study was conducted to use the enzyme-induced calcium carbonate precipitation (EICP) technique from soybean crude extract urease along coconut fiber derived biochar’s (CFB) to bioremediate lead. To study the desorption rates of heavy metals from the soil, lead (Pb) was added to the soil at load ratios of 50 and 100 mg/kg. There were five separate treatment soil columns created: control sample, only CFB, only EICP, EICP with 2% (w/w) CFB, and EICP with 4% (w/w) CFB. Laboratory scale experiment demonstrates significant lead removal from soil. The amount of CaCO₃ precipitated in the soil was measured using a gravimetric acid digestion test, which related heavy metal desorption to the amount of precipitated calcium carbonate. These findings were validated using a scanning electron microscope (SEM), which revealed calcium carbonate and lead coprecipitation. As a result, the study reveals that the EICP technique, in conjunction with coconut fiber biochar, could be an efficient alternative in the remediation of heavy metal ion-contaminated soils.

Keywords: enzyme induced calcium carbonate precipitation (EICP), coconut fiber derived biochar’s (CFB), bioremediation, heavy metal

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Authors: Harshada Vaidya-Kannur, Dattatraya Naik

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Propolis, one of the beehive products also referred as bee-glue is sticky dark coloured complex mixture of compounds. The volatile oil can be isolated from the propolis by hydrodistillation. The mark that is left behind after the removal of volatile oil is referred as the de-oiled propolis. Antioxidant as well as anti-inflammatory properties of total ethanolic extract of de-oiled propolis (TEEDP) was investigated. Another lot of deoiled propolis was successively exacted with hexane, ethyl acetate and ethanol. Activities of these fractions were also determined. Antioxidant activity was determined by studying ABTS, DPPH and NO radical scavenging. Determination of anti-inflammatory activity was carried out by topical TPA induced mouse ear oedema model. It is noteworthy that ethyl acetate fraction of deoiled propolis (EAFDP) exhibited 49.45 % TEAC activity at the concentration 0.2 mg/ml which is equivalent to the activity of trolox at the concentration 0.2 mg/ml. Its DPPH scavenging activity (72.56%) was closely comparable to that of trolox (75%). However its NO scavenging activity was comparatively low. From IC50 values it could be concluded that the efficiency of scavenging ABTS radicals by the de-oiled propolis was more pronounced as compared to scavenging of other radicals. Studies by TPA induced mouse ear inflammation model indicated that the de-oiled propolis of Indian origin had significant topical anti-inflammatory activity. The EAFDP was found to be the most active fraction for this activity also. The purification of EAFP yielded six pure crystalline compounds. These compounds were identified by their physical data and spectral data.

Keywords: anti-inflammatory activity, anti-oxidant activity, column chromatography, de-oiled propolis

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Authors: Misha Ali, Qayyum Husain, Nida Alam, Masood Ahmad

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Improving the activity and stability of the enzyme is an important aspect in bioremediation processes. Immobilization of enzyme is an efficient approach to amend the properties of biocatalyst required during wastewater treatment. The present study was done to immobilize partially purified ginger peroxidase on amino functionalized silica coated titanium dioxide nanocomposite. Interestingly there was an enhancement in enzyme activity after immobilization on nanosupport which was evident from effectiveness factor (η) value of 1.76. Immobilized enzyme was characterized by transmission electron microscopy, scanning electron microscopy and Fourier transform infrared spectroscopy. Immobilized peroxidase exhibited higher activity in a broad range of pH and temperature as compared to free enzyme. Also, the thermostability of peroxidase was strikingly improved upon immobilization. After six repeated uses, the immobilized peroxidase retained around 62% of its dye decolorization activity. There was a 4 fold increase in Vmax of immobilized peroxidase as compared to free enzyme. Circular dichroism spectroscopy demonstrated conformational changes in the secondary structure of enzyme, a possible reason for the enhanced enzyme activity after immobilization. Immobilized peroxidase was highly efficient in the removal of acid yellow 42 dye in a stirred batch process. Our study shows that this bio-remediating system has remarkable potential for treatment of aromatic pollutants present in wastewater.

Keywords: acid yellow 42, decolorization, ginger peroxidase, immobilization

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Authors: Rejane Maria P. da Silva, Mariana X. Milagre, João Victor de S. Araujo, Leandro A. de Oliveira, Renato A. Antunes, Isolda Costa

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The Al-Cu-Li alloys are advanced materials for aerospace application because of their interesting mechanical properties and low density when compared with conventional Al-alloys. However, Al-Cu-Li alloys are susceptible to localized corrosion. The near-surface deformed layer (NSDL) induced by the rolling process during the production of the alloy and its removal by polishing can influence on the corrosion susceptibility of these alloys. In this work, the influence of surface preparation effects on the electrochemical activity of AA2098-T351 (Al–Cu–Li alloy) was investigated using a correlation between surface chemistry, microstructure, and electrochemical activity. Two conditions were investigated, polished and as-received surfaces of the alloy. The morphology of the two types of surfaces was investigated using confocal laser scanning microscopy (CLSM) and optical microscopy. The surface chemistry was analyzed by X-ray Photoelectron Spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS). Global electrochemical techniques (potentiodynamic polarization and EIS technique) and a local electrochemical technique (Localized Electrochemical Impedance Spectroscopy-LEIS) were used to examine the electrochemical activity of the surfaces. The results obtained in this study showed that in the as-received surface, the near-surface deformed layer (NSDL), which is composed of Mg-rich bands, influenced the electrochemical behavior of the alloy. The results showed higher electrochemical activity to the polished surface condition compared to the as-received one.

Keywords: Al-Cu-Li alloys, surface preparation effects, electrochemical techniques, localized corrosion

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Authors: Satya Pradhan, Venky Nanniyur

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As the software industry transitions from a license-based model to a subscription-based Software-as-a-Service (SaaS) model, many software development groups are using a hybrid development model that incorporates Agile and Waterfall methodologies in different parts of the organization. The traditional metrics used for measuring software quality in Waterfall or Agile paradigms do not apply to this new hybrid methodology. In addition, to respond to higher quality demands from customers and to gain a competitive advantage in the market, many companies are starting to prioritize quality as a strategic differentiator. As a result, quality metrics are included in the decision-making activities all the way up to the executive level, including board of director reviews. This paper presents key challenges associated with measuring software quality in organizations using the hybrid development model. We introduce a framework called Prevention-Inspection-Evaluation-Removal (PIER) to provide a comprehensive metric definition for hybrid organizations. The framework includes quality measurements, quality enforcement, and quality decision points at different organizational levels and project milestones. The metrics framework defined in this paper is being used for all Cisco systems products used in customer premises. We present several field metrics for one product portfolio (enterprise networking) to show the effectiveness of the proposed measurement system. As the results show, this metrics framework has significantly improved in-process defect management as well as field quality.

Keywords: quality management system, quality metrics framework, quality metrics, agile, waterfall, hybrid development system

Procedia PDF Downloads 174

Authors: Sarre Nzaba, Bulelwa Ntsendwana, Bekkie Mamba, Alex Kuvarega

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Elimination of toxic organic compounds from wastewater is currently one of the most important subjects in water pollution control. The discharge of azo dyes such as Brilliant black (BB) into the water bodies has carcinogenic and mutagenic effects on humankind and the ecosystem. Conventional water treatment techniques fail to degrade these dyes completely thereby posing more problems. Advanced oxidation processes (AOPs) are promising technologies in solving the problem. Anatase type nitrogen-platinum (N,Pt) co-doped TiO₂ photocatalyts were prepared by a modified sol-gel method using amine terminated polyamidoamine generation 1 (PG1) as a template and source of nitrogen. SEM/ EDX, TEM, XRD, XPS, TGA, FTIR, RS, PL and UV-Vis were used to characterize the prepared nanomaterials. The synthesized photocatalysts exhibited lower band gap energies as compared to the commercial TiO₂ revealing a shift in band gap towards the visible light absorption region. Photocatalytic activity of N,Pt co-doped TiO₂ was measured by the reaction of photocatalytic degradation of BB dye. Enhanced photodegradation efficiency of BB was achieved after 180 min reaction time with initial concentration of 50 ppm BB solution. This was attributed to the rod-like shape of the materials, larger surface area, and enhanced absorption of visible light induced by N,Pt co-doping. The co-doped N,Pt also exhibited pseudo-first order kinetic behaviour with half-life and rate constant of 0.37 min 0.1984 min⁻¹ and respectively. N doped TiO₂ and N,Pt co-doped TiO₂ exhibited enhanced photocatalytic performances for the removal of BB from water.

Keywords: N, Pt co-doped TiO₂, dendrimer, photodegradation, visible-light

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Authors: Patrick Dzimiri

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This chapter discusses the military-orchestrated leadership change in Zimbabwe that transpired in November 2017. Fundamentally, the chapter provides a critical examination of military interference in the country's politics and its implications for a political transition in the post-Mugabe dispensation. This chapter offers insight into Zimbabwe's political crises propelled by the lack of a succession plan. It emerged that the succession battle within ZANU-PF got complicated by the militarisation of factionalism. The chapter builds from an extensive review of primary and secondary data sources on political developments before and post-Mugabe era. Vilfredo Pareto's (1848-18923) theory on elite circulation is deployed herein to explain the absence of a succession mechanism within ZANU-PF and the militarisation of socio-politics life Zimbabwe. The chapter argues that what transpired in Zimbabwe’s power wrangle within the ZANU-PF political elites was triggered by a lack of a clear succession policy. Building from insights offered by Pareto's theory of elite circulation, it is averred that the removal of Mugabe by the military did not herald any form of political transition but rather a mere power play of one elite replacing another. In addition, it is argued that the lack of political reform by the Mnangagwa government affirms the position that political elites seek power for personal self-actualisation and not the public good. The chapter concludes that Mnangagwa's rise to power is nothing but a new elite displacing the old elite structure and does not herald a positive transition and transformation in the politics of Zimbabwe.

Keywords: military, politics, zimbabwe, governance, political transition

Procedia PDF Downloads 94

Authors: Alireza Abbassi Monjezi, Mohammad Hasan Shaheed

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Flood, caused by excessive rainfall, monsoon, cyclone and tsunami is a common disaster in many countries of the world especially sea connected low-lying countries. A stand-alone self-powered water filtration module for decontamination of floodwater has been designed and modeled. A combination forward osmosis – low pressure reverse osmosis (FO-LPRO) system powered by solar photovoltaic-thermal (PVT) energy is investigated which could overcome the main barriers to water supply for remote areas and ensure off-grid filtration. The proposed system is designed to be small scale and portable to provide on-site potable water to communities that are no longer themselves mobile nor can be reached quickly by the aid agencies. FO is an osmotically driven process that uses osmotic pressure gradients to drive water across a controlled pore membrane from a feed solution (low osmotic pressure) to a draw solution (high osmotic pressure). This drops the demand for high hydraulic pressures and therefore the energy demand. There is also a tendency for lower fouling, easier fouling layer removal and higher water recovery. In addition, the efficiency of the PVT unit will be maximized through freshwater cooling which is integrated into the system. A filtration module with the capacity of 5 m3/day is modeled to treat floodwater and provide drinking water. The module can be used as a tool for disaster relief, particularly in the aftermath of flood and tsunami events.

Keywords: flood resilience, membrane desalination, portable water treatment, solar energy

Procedia PDF Downloads 288

Authors: Ghulam Murshid

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Carbon dioxide is one of the major greenhouse gas (GHG) contributors. It is an obligation of the industry to reduce the amount of carbon dioxide emission to the acceptable limits. Tremendous research and studies are reported in the past and still the quest to find the suitable and economical solution of this problem needed to be explored in order to develop the most plausible absorber for carbon dioxide removal. Amino acids are reported by the researchers as a potential solvent for absorption of carbon dioxide to replace alkanolamines due to its ability to resist oxidative degradation, low volatility due to its ionic structure and higher surface tension. In addition, the introduction of promoter-like piperazine to amino acid helps to further enhance the solubility. In this work, the effect of piperazine on thermophysical properties and solubility of β-Alanine aqueous solutions were studied for various concentrations. The measured physicochemical properties data was correlated as a function of temperature using least-squares method and the correlation parameters are reported together with it respective standard deviations. The effect of activator piperazine on the CO2 loading performance of selected amino acid under high-pressure conditions (1bar to 10bar) at temperature range of (30 to 60)oC was also studied. Solubility of CO2 decreases with increasing temperature and increases with increasing pressure. Quadratic representation of solubility using Response Surface Methodology (RSM) shows that the most important parameter to optimize solubility is system pressure. The addition of promoter increases the solubility effect of the solvent.

Keywords: amino acids, co2, global warming, solubility

Procedia PDF Downloads 414

Authors: Khyamling Parane, B. M. Prabhu Prasad, Basavaraj Talawar

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Fast simulations are critical in reducing time to market in CMPs and SoCs. Several simulators have been used to evaluate the performance and power consumed by Network-on-Chips. Researchers and designers rely upon these simulators for design space exploration of NoC architectures. Our experiments show that simulating large NoC topologies take hours to several days for completion. To speed up the simulations, it is necessary to investigate and optimize the hotspots in simulator source code. Among several simulators available, we choose Booksim2.0, as it is being extensively used in the NoC community. In this paper, we analyze the cache and memory system behaviour of Booksim2.0 to accurately monitor input dependent performance bottlenecks. Our measurements show that cache and memory usage patterns vary widely based on the input parameters given to Booksim2.0. Based on these measurements, the cache configuration having least misses has been identified. To further reduce the cache misses, we use software optimization techniques such as removal of unused functions, loop interchanging and replacing post-increment operator with pre-increment operator for non-primitive data types. The cache misses were reduced by 18.52%, 5.34% and 3.91% by employing above technology respectively. We also employ thread parallelization and vectorization to improve the overall performance of Booksim2.0. The OpenMP programming model and SIMD are used for parallelizing and vectorizing the more time-consuming portions of Booksim2.0. Speedups of 2.93x and 3.97x were observed for the Mesh topology with 30 × 30 network size by employing thread parallelization and vectorization respectively.

Keywords: cache behaviour, network-on-chip, performance profiling, vectorization

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Authors: B. Kenny, M. Dixon, A. Boshell

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The use of alcoholic surgical prep was recently introduced into the Royal Newcastle Center for elective procedures. In the past 3 months there have been a significant number of burns believed to be related to ‘pooling’ of this surgical prep in patients undergoing procedures where they are placed in the lateral position with hip bolsters. The aim of the audit was to determine the reason for the burns, analyze what pre-existing factors may contribute to the development of the burns and what can be changed to prevent further burns occurring. All patients undergoing a procedure performed on the hip who were placed in the lateral position with sacral and anterior, superior iliac spine (ASIS) support with ‘bolsters’ were included in the audit. Patients who developed a ‘burn’ were recorded, details of the surgery, demographics, surgical prep used and length of surgery were obtained as well as photographs taken to document the burn. Measures were then taken to prevent further burns and the efficacy was documented. Overall 14 patients developed burns over the ipsilateral ASIS. Of these, 13 were Total Hip Arthroplasty (THA) and 1 was a removal of femoral nail. All patients had Chlorhexidine 0.5% in Alcohol 70% Tinted Red surgical preparation or Betadine Alcoholic Skin Prep (70% etoh). Patients were set up in the standard lateral decubitus position with sacral and bilateral ASIS bolsters with a valband covering. 86% of patients were found to have pre-existing hypersensitivities to various substances. There is very little literature besides a few case reports on surgical prep-related burns. The case reports that do exist are related to the use of tourniquet-related burns and there is no mention in the literature examining ‘bolster’ related burns. The burns are hypothesized to be caused by pooling of the alcoholic solution which is amplified by the use of Valband.

Keywords: arthroplasty, chemical burns, wounds, rehabilitation

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Authors: Genevieve D. Fernandes, Nisha P. Naik

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All through the ages in all human civilizations, men have been engaged in construction activity, not only to build their dwellings and house their activities, but also roads, bridges to facilitate means of transport, and communication etc. The main concern in this activity was to ensure safety and reduce the collapse of the buildings and other structures. But even after taking all precautions, it is impossible to guarantee safety and collapse because of several unforeseen reasons like faulty constructions, design errors, overloading, soil liquefaction, gas explosion, material degradation, terrorist attacks and economic factors also contributing to the collapse. It is also uneconomical to design the structure for unforeseen events unless they have a reasonable chance of occurrence. In order to ensure safety and prevent collapse, many guidelines have been framed by local bodies and government authorities in many countries like the United States Department of Defence (DOD), United States General Service Administration (GSA) and Euro-Codes in European Nations. Some other practices are followed to incorporate redundancies in the structure like detailing, ductile designs, tying of elements at particular locations, and provision of hinges and interconnections. It is also to be admitted that a full-proof safe design structure for accidental events cannot be prepared and implemented as it is uneconomical and the chances of such occurrences are less. This paper reviews past case studies of the collapse of structures with the aim of developing an understanding of the collapse mechanism. This study will definitely help to bring about a detailed improvement in the design to maximise the quality of the construction at a minimal cost.

Keywords: unforeseen factors, progressive collapse, collapse resisting mechanisms, column removal scenario

Procedia PDF Downloads 137

Authors: Qingying Liu, S. Liu, L. Hao, B. Zhang, J. D. Yan

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HVDC technology is becoming increasingly popular due to its simplicity in topology and less power loss over long distance of power transmission, in comparison with HVAC technology. However, the dielectric behavior of insulators in the long term under HVDC stress is completely different from that under HVAC stress as a result of charge accumulation in a constant electric field. Insulators used in practical systems are never perfect in their structural conditions. Over time shallow cracks may develop on their surface. The presence of defects can lead to drastic change in their dielectric behaviour and thus increase the probability of surface flashover. In this contribution, experimental investigations have been carried out on the charge accumulation phenomenon on the surface of a rod insulator made of epoxy that is placed between two disk shaped electrodes at different voltage levels and in different gases (SF6, CO2 and N2). Many results obtained, such as, the two-dimensional electrostatic potential distribution along the insulator surface after the removal of the power source following a pre-defined period of application. The probe has been carefully calibrated before each test. Results show that surface charge distribution near the two disk shaped electrodes is not uniform in the circumferential direction, possibly due to the imperfect electrical connections between the embeded conductor in the insulator and the disk shaped electrodes. The axial length of this non-uniform region is experimentally determined, which provides useful information for shielding design. A charge transport model is also used to explain the formation of the long term electrostatic potential distribution under a constant applied voltage.

Keywords: HVDC, power systems, dielectric behavior, insulation, charge accumulation

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Authors: Askar Kilmametov, Julia Ivanisenko, Boris Straumal, Horst Hahn

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The high-pressure α- to ω-phase transition was discovered in elemental Ti and Zr fifty years ago using static high pressure and then observed to appear between 2 and 12 GPa at room temperature, depending on the experimental technique, the pressure environment, and the sample purity. The fact that ω-phase is retained in a metastable state in ambient condition after the removal of the pressure has been used to check the changes in magnetic and superconductive behavior, electron band structure and mechanical properties. However, the fundamental knowledge on a combination of both mechanical treatment and high applied pressure treatments for ω-phase formation in Ti alloys is currently lacking and has to be studied in relation to improved mechanical properties of bulk nanostructured states. In the present study, nanostructured (α+β) Ti alloys containing β-stabilizing elements such as Co, Fe, Cr, Nb were performed by severe plastic deformation, namely high pressure torsion (HPT) technique. HPT-induced α- to ω-phase transformation was revealed in dependence on applied pressure and shear strains by means of X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. The transformation kinetics was compared with the kinetics of pressure-induced transition. Orientation relationship between α-, β- and ω-phases was taken into consideration and analyzed according to theoretical calculation proposed earlier. The influence of initial state before HPT appeared to be considerable for subsequent α- to ω-phase transition. Thermal stability of the HPT-induced ω-phase was discussed as well in the frame of mechanical behavior of Ti and Ti-based alloys produced by shear deformation under high applied pressure.

Keywords: bulk nanostructured materials, high pressure phase transitions, severe plastic deformation, titanium alloys

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Authors: Asma Bashir, Neha Farid, Kashif Ali, Kiran Fatima

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Background: Bacteriocins are a subclass of antimicrobial peptides that are becoming extremely important in treatments. It is possible to utilise bacteriocins in place of or in addition to traditional antibiotics. It is possible to treat a variety of infections, including Vancomycin-Resistant Staphylococcus aureus (VRSA) and Methicillin-Resistant Staphylococcus aureus (MRSA), using the targeted spectrum of activity of these microorganisms. Method: This study aimed to examine the efficiency of antibiotics and bacteriocin against VRSA and MRSA. The effects of bacteriocins, such as enterocin KAE01, enterocin KAE03, enterocin KAE05, and enterocin KAE06 isolated from Enterococcus faecium strains, alone and in combination with vancomycin and methicillin antibiotics were examined. The selection technique utilized the minimum inhibitory concentrations (MICs) against Gram-positive indicator strain ATCC 6538 Methicillin-Resistant Staphylococcus aureus (MRSA) and indicator strain KSA 02 Vancomycin-Resistant Staphylococcus aureus (VRSA). Results: We report the isolation and identification of enterocins KAE01, KAE03, KAE05, and KAE06 from food isolates of Enterococcus faecium (KAE01, KAE03, KAE05, and KAE06). After isolating the protein, it was partially purified with ammonium sulphate precipitation and purified with fast protein liquid chromatography (FPLC) procedures. Combinations of enterocin KAE01, 1 citric acid, 1 lactic acid, and microcin J25, 1 reuterin, 1 citric acid, and microcin J25, 1 reuterin, 1 lactic acid shown synergistic benefits (FIC index = 0.5) against Vancomycin-Resistant Staphylococcus aureus (VRSA). In addition, a moderately synergistic (FIC index = 0.75) interaction was seen between pediocin PA-1, 1 citric acid, 1 lactic acid, and reuterin 1 citric acid, 1 lactic acid against L. ivanovii HPB28. In the presence of acids, nisin Z exhibited a modestly synergistic effect (FIC index = 0.625-0.75); however, it exhibited additive effects (FIC index = 1) when combined with reuterin or pediocin PA-1 against L. ivanovii HPB28. The efficacy of synergistic consortiums against Gram-positive bacteria was examined. Conclusion: Combining antimicrobials with various modes of action boosted efficacy and expanded the spectrum of inhibition, particularly against multidrug-resistant pathogens, according to our research.

Keywords: Enterococcus faecium, bacteriocin, antimicrobial resistance, antagonistic activity, vancomycin-resistant Staphylococcus aureus, methicillin-resistant Staphylococcus aureus

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Authors: Muhammad Mohsin, Mir Md Abdus Salam, Pertti Pulkkinen, Ari Pappinen

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Soil and water contamination by heavy metals is a major challenging issue for the environment. Phytoextraction is an emerging, environmentally friendly and cost-efficient technology in which plants are used to eliminate pollutants from the soil and water. We aimed to assess the copper (Cu) and zinc (Zn) removal efficiency by two willow varieties such as Klara (S. viminalis x S. schwerinii x S. dasyclados) and Karin ((S.schwerinii x S. viminalis) x (S. viminalis x S.burjatica)) under different soil treatments (control/unpolluted, polluted, lime with polluted, wood ash with polluted). In 180 days of pot experiment, these willow varieties were grown in a highly polluted soil collected from Pyhasalmi mining area in Finland. The lime and wood ash were added to the polluted soil to improve the soil pH and observe their effects on metals accumulation in plant biomass. The Inductively Coupled Plasma Optical Emission Spectrometer (ELAN 6000 ICP-EOS, Perkin-Elmer Corporation) was used in this study to assess the heavy metals concentration in the plant biomass. The result shows that both varieties of willow have the capability to accumulate the considerable amount of Cu and Zn varying from 36.95 to 314.80 mg kg⁻¹ and 260.66 to 858.70 mg kg⁻¹, respectively. The application of lime and wood ash substantially affected the stimulation of the plant height, dry biomass and deposition of Cu and Zn into total plant biomass. Besides, the lime application appeared to upsurge Cu and Zn concentrations in the shoots and leaves in both willow varieties when planted in polluted soil. However, wood ash application was found more efficient to mobilize the metals in the roots of both varieties. The study recommends willow plantations to rehabilitate the Cu and Zn polluted soils.

Keywords: heavy metals, lime, phytoextraction, wood ash, willow

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Authors: Meera Tandan, Mohan Timilsina, Martin Cormican, Akke Vellinga

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Background: In general practice, many infections are treated empirically without microbiological confirmation. Understanding susceptibility of antimicrobials during empirical prescribing can be helpful to reduce inappropriate prescribing. This study aims to apply a prediction model using a decision tree approach to predict the antimicrobial resistance (AMR) of urinary tract infections (UTI) based on non-clinical features of patients over 65 years. Decision tree models are a novel idea to predict the outcome of AMR at an initial stage. Method: Data was extracted from the database of the microbiological laboratory of the University Hospitals Galway on all antimicrobial susceptibility testing (AST) of urine specimens from patients over the age of 65 from January 2011 to December 2014. The primary endpoint was resistance to common antimicrobials (Nitrofurantoin, trimethoprim, ciprofloxacin, co-amoxiclav and amoxicillin) used to treat UTI. A classification and regression tree (CART) model was generated with the outcome ‘resistant infection’. The importance of each predictor (the number of previous samples, age, gender, location (nursing home, hospital, community) and causative agent) on antimicrobial resistance was estimated. Sensitivity, specificity, negative predictive (NPV) and positive predictive (PPV) values were used to evaluate the performance of the model. Seventy-five percent (75%) of the data were used as a training set and validation of the model was performed with the remaining 25% of the dataset. Results: A total of 9805 UTI patients over 65 years had their urine sample submitted for AST at least once over the four years. E.coli, Klebsiella, Proteus species were the most commonly identified pathogens among the UTI patients without catheter whereas Sertia, Staphylococcus aureus; Enterobacter was common with the catheter. The validated CART model shows slight differences in the sensitivity, specificity, PPV and NPV in between the models with and without the causative organisms. The sensitivity, specificity, PPV and NPV for the model with non-clinical predictors was between 74% and 88% depending on the antimicrobial. Conclusion: The CART models developed using non-clinical predictors have good performance when predicting antimicrobial resistance. These models predict which antimicrobial may be the most appropriate based on non-clinical factors. Other CART models, prospective data collection and validation and an increasing number of non-clinical factors will improve model performance. The presented model provides an alternative approach to decision making on antimicrobial prescribing for UTIs in older patients.

Keywords: antimicrobial resistance, urinary tract infection, prediction, decision tree

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Authors: G. Hosseini, A. Sadighzadeh, M. Rahimnejad, N. Hosseini, Z. Jamalzadeh

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Metal pollutants, especially heavy metals from anthropogenic sources such as metallurgical industries’ waste including mining, smelting, casting or production of nuclear fuel, including mining, concentrate production and uranium processing ends in the environment contamination (water and soil) and risk to human health around the facilities of this type of industrial activity. There are different methods that can be used to remove these contaminants from water and soil. These are very expensive and time-consuming. In this case, the people have been forced to leave the area and the decontamination is not done. For example, in the case of Chernobyl accident, an area of 30 km around the plant was emptied of human life. A very efficient and cost-effective method for decontamination of the soil and the water is phytoremediation. In this method, the plants preferentially native plants which are more adaptive to the regional climate are well used. In this study, three types of plants including Alfalfa, Sunflower and wheat were used to Barium decontamination. Alfalfa and Sunflower were not grown good enough in Saghand mine’s soil sample. This can be due to non-native origin of these plants. But, Wheat rise in Saghand Uranium Mine soil sample was satisfactory. In this study, we have investigated the effect of 4 types of acids inclusive nitric acid, oxalic acid, acetic acid and citric acid on the removal efficiency of Barium by Wheat. Our results indicate the increase of Barium absorption in the presence of citric acid in the soil. In this paper, we will present our research and laboratory results.

Keywords: phytoremediation, heavy metal, wheat, soil

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Authors: Adedoyin Opeyemi Osokoya

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The study assesses the influence of social media on perceived learning outcome of agricultural science students in tertiary institutions in Oyo state, Nigeria. The four-stage sampling procedure was used to select participants. All students in the seven tertiary institutions that offer agriculture science as a course of study in Oyo State was the population. A university, a college of agriculture and a college of education were sampled, and a department from each was randomly selected. Twenty percent of the students’ population in the respective selected department gave a sample size of 165. Questionnaire was used to collect information on respondents’ personal characteristics and information related to access to social media. Data were analysed using descriptive statistics, chi-square, correlation, and multiple regression at the 0.05 confidence level. Age and household size were 21.13 ± 2.64 years and 6 ± 2.1 persons respectively. All respondents had access to social media, majority (86.1%) owned Android phone, 57.6% and 52.7% use social media for course work and entertainment respectively, while the commonly visited sites were WhatsApp, Facebook, Google, Opera mini. Over half (53.9%) had an unfavourable attitude towards the use of social media for learning; benefits of the use of social media for learning was high (56.4%). Removal of information barrier created by distance (x̄=1.58) was the most derived benefit, while inadequate power supply (x̄=2.36), was the most severe constraints. Age (β=0.23), sex (β=0.37), ownership of Android phone (β=-1.29), attitude (β=0.37), constraints (β =-0.26) and use of social media (β=0.23) were significant predictors of influence on perceived learning outcomes.

Keywords: use of social media, agricultural science students, undergraduates of tertiary institutions, Oyo State of Nigeria

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Authors: Carolina Gutierrez-Cortes, Hector Suarez, Gustavo Buitrago

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Bacteriocins are antimicrobial peptides produced by bacteria as a competitive strategy for substrate and habitat. Those peptides have a potential use as food biopreservatives due to their antimicrobial activity against foodborne pathogens, avoiding the use of additives that can be harmful to consumers. The industrial production of bacteriocins is currently expensive; one of the options to be competitive is the development of economic culture media, for example, with the use of agro-industrial wastes such as whey. This study evaluated the growth and production of bacteriocins from four strains: Pediococcus pentosaceus 63, Pediococcus pentosaceus 145, Pediococcus pentosaceus 146 and Pediococcus pentosaceus 147 isolated from ‘minas cheese’ (artisanal cheese made from raw milk in the state of Minas Gerais, Brazil) in order to select a strain with growth at high rates and higher antimicrobial activity against Listeria monocytogenes 104 after incubation on the culture medium designed with whey and other components. The media used were: MRS broth, modified MRS broth (using different sources of carbon and nitrogen and different amounts of micronutrients) and a culture medium designed by a factorial design using whey and other components. The final biomass concentrations of the four strains in MRS broth after 24 hours of incubation were very similar 9.25, 9.33, 9.25 and 9.22 (log CFU/mL) for P. pentosaceus 63, P. pentosaceus 145, P. pentosaceus 146 and P. pentosaceus 147 respectively. In the same assays, antimicrobial activity of 3200 AU/mL for the first three and of 12800 AU/mL for P. pentosaceus 147 were obtained. Culture of P. pentosaceus 63 on modified MRS broth, showed the effect of some sources of carbon on the activity of bacteriocin, obtaining 12800 AU/mL with dextrose and 25600 AU/mL with maltose. Cultures of P. pentosaceus 145, 146 and 147 with these same sugars presented activity of 12800 AU/mL. It was observed that the modified MRS medium using whey increased the antimicrobial activity of the strains at 16000, 6400, 16000 and 19200 AU/mL for each strain respectively, keeping the biomass at values close to 9 log units. About nitrogen sources, it was observed that the combination of peptone (10 g /L), meat extract (10 g/L) and yeast extract (5 g/L) promoted the highest activity (12800 AU/mL), and in all cases MgSO4, MnSO4, K2HPO4 and ammonium citrate at low concentrations adversely affected bacteriocin production. Because P. pentosaceus 147 showed the highest antimicrobial activity in the presence of whey, it was used to evaluate the culture medium (peptone (10 g/L), meat extract (8 g/L), yeast extract (2 g/L), Tween® 80 (1 g/L), ammonium citrate (2 g/L), sodium acetate (5 g/L), MgSO4 (0.2 g/L), MnSO4 (0.04 g/L)). With the designed medium added with whey, 9.34 log units of biomass concentration and 19200 AU/mL were achieved for P. pentosaceus 147. The above suggest that the new medium promotes the antimicrobial activity of P. pentosaceus 147 allowing the use of an economic medium using whey.

Keywords: antimicrobial activity, bacteriocins, pediococcus, whey

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Authors: Sarina Sahmeddini, Fahimeh Safarpour, Forough Pazhuheian

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With the concepts of minimally invasive treatment and preventive dentistry gaining more and more recognition by dentists, there are many published clinical trials comparing the use of the erbium laser with traditional drilling for caries removal. However, the efficacy of the erbium laser is still controversial. The aim of this review study is to compare the effects of tooth preparation by laser irradiation and conventional preparation by bur to identify the best means for cavity preparation and reduction of recurrent caries. Randomized controlled trials, controlled clinical trials, and prospective, and retrospective cohort studies were included in this review. The eligibility criteria included studies in humans’ permanent teeth in which cavities were conducted in their cervical third and proximal surfaces. PubMed, Google scholar, and Scopus about Er:YAG laser and bur prepared cavities were carried out. The studies’ details were organized in four tables according to the groups: (1) Microleakage; (2) Morphological changes; (3) Microhardness; and (4) Bond strength. The initial search resulted in 134 articles, 12 studies published from 2012 up to March 2020 were included in this review. According to the risk of bias evaluation, all studies were classified as high quality. Clinical implications: Er:YAG lasers with the energy levels between 250 to 300 mJ can be proper alternatives to conventional burs, as minimal invasive instruments with no significant differences or better results in microleakage, microhardness, and bond strength compared with conventional burs. In conclusion, Er:YAG laser irradiations accompanied by phosphoric acid etching can reduce the chance of recurrent carries.

Keywords: lasers, drilling, caries, micro leakage

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Authors: Olivier Delage, Hassan Bencherif, Alain Bourdier

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Signal decomposition approaches represent an important step in time series analysis, providing useful knowledge and insight into the data and underlying dynamics characteristics while also facilitating tasks such as noise removal and feature extraction. As most of observational time series are nonlinear and nonstationary, resulting of several physical processes interaction at different time scales, experimental time series have fluctuations at all time scales and requires the development of specific signal decomposition techniques. Most commonly used techniques are data driven, enabling to obtain well-behaved signal components without making any prior-assumptions on input data. Among the most popular time series decomposition techniques, most cited in the literature, are the empirical mode decomposition and its variants, the empirical wavelet transform and singular spectrum analysis. With increasing popularity and utility of these methods in wide ranging applications, it is imperative to gain a good understanding and insight into the operation of these algorithms. In this work, we describe all of the techniques mentioned above as well as their ability to denoise signals, to capture trends, to identify components corresponding to the physical processes involved in the evolution of the observed system and deduce the dimensionality of the underlying dynamics. Results obtained with all of these methods on experimental total ozone columns and rainfall time series will be discussed and compared

Keywords: denoising, empirical mode decomposition, singular spectrum analysis, time series, underlying dynamics, wavelet analysis

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Authors: A. Mulry, C. Kealey, D. B. Brady

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Planktonic bacteria can form biofilms which are microbial aggregates embedded within a matrix of extracellular polymeric substances (EPS). They can be found attached to abiotic or biotic surfaces. Biofilms are responsible for oral diseases such as dental caries, gingivitis and the progression of periodontal disease. Biofilms can resist 500 to 1000 times the concentration of biocides and antibiotics used to kill planktonic bacteria. Biofilm development on oral surfaces involves four stages, initial attachment, early development, maturation and dispersal of planktonic cells. The Minimum Inhibitory Concentration (MIC) was determined using a range of saturated and unsaturated fatty acids using the resazurin assay, followed by serial dilution and spot plating on BHI agar plates to establish the Minimum Bactericidal Concentration (MBC). Log reduction of bacteria was also evaluated for each fatty acid. The Minimum Biofilm Inhibition Concentration (MBIC) was determined using crystal violet assay in 96 well plates on forming and pre-formed S. mutans biofilms using BHI supplemented with 1% sucrose. Saturated medium-chain fatty acids Octanoic (C8.0), Decanoic (C10.0) and Undecanoic acid (C11.0) do not display strong antibiofilm properties; however, Lauric (C12.0) and Myristic (C14.0) display moderate antibiofilm properties with 97.83% and 97.5% biofilm inhibition with 1000 µM respectively. Monounsaturated, Oleic acid (C18.1) and polyunsaturated large chain fatty acids, Linoleic acid (C18.2) display potent antibiofilm properties with biofilm inhibition of 99.73% at 125 µM and 100% at 65.5 µM, respectively. Long-chain polyunsaturated Omega-3 fatty acids α-Linoleic (C18.3), Eicosapentaenoic Acid (EPA) (C20.5), Docosahexaenoic Acid (DHA) (C22.6) have displayed strong antibiofilm efficacy from concentrations ranging from 31.25-250µg/ml. DHA is the most promising antibiofilm agent with an MBIC of 99.73% with 15.625µg/ml. This may be due to the presence of six double bonds and the structural orientation of the fatty acid. To conclude, fatty acids displaying the most antimicrobial activity appear to be medium or long-chain unsaturated fatty acids containing one or more double bonds. Most promising agents include Omega-3-fatty acids Linoleic, α-Linoleic, EPA and DHA, as well as Omega-9 fatty acid Oleic acid. These results indicate that fatty acids have the potential to be used as antimicrobials and antibiofilm agents against S. mutans. Future work involves further screening of the most potent fatty acids against a range of bacteria, including Gram-positive and Gram-negative oral pathogens. Future work will involve incorporating the most effective fatty acids onto dental implant devices to prevent biofilm formation.

Keywords: antibiofilm, biofilm, fatty acids, S. mutans

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Authors: Anne McCarthy, Anna Kim, Yin Song, Kyoo Jo, Donald Cropek, Sungmin Hong

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Corrosion prevention remains an indispensable concern across a spectrum of industries, demanding inventive and adaptable methodologies to effectively tackle the ever-evolving obstacles presented by corrosive surroundings. This abstract introduces a pioneering approach to corrosion prevention that amalgamates the distinct attributes of magneto-responsive polymers with finely adjustable hydrophobicity inspired by the structure of cicada wings, effectively deterring bacterial proliferation and biofilm formation. The proposed strategy entails the creation of an innovative array of magneto-responsive nanostructures endowed with the capacity to dynamically modulate their hydrophobic characteristics. This dynamic control over hydrophobicity facilitates active repulsion of water and corrosive agents on demand. Additionally, the cyclic motion generated by magnetic activation prevents the biofilms formation and rejection. Thus, the synergistic interplay between magneto-active nanostructures and hydrophobicity manipulation establishes a versatile defensive mechanism against diverse corrosive agents. This study introduces a novel method for corrosion prevention, harnessing the advantages of magneto-active nanostructures and the precision of hydrophobicity adjustment, resulting in water-repellency, effective biofilm removal, and offering a promising solution to handle corrosion-related challenges. We believe that the combined effect will significantly contribute to extending asset lifespan, improving safety, and reducing maintenance costs in the face of corrosion threats.

Keywords: magneto-active material, nanoimprinting, corrosion prevention, hydrophobicity

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Authors: Mun Yee Chan, Sin Ming Goh, Lisa Gaik Ai Ong

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Approximately 10,000 different types of dyes and pigments are being used in various industrial applications yearly, which include the textile and printing industries. However, these dyes are difficult to degrade naturally once they enter the aquatic system. Their high persistency in natural environment poses a potential health hazard to all form of life. Hence, there is a need for alternative dye removal strategy in the environment via bioremediation. In this study, fungi laccase is investigated via commercial agar dyes plates and submerged fermentation to explore the application of fungi laccase in textile dye wastewater treatment. Two locally isolated basidiomycetes were screened for laccase activity using media added with commercial dyes such as 2, 2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS), guaiacol and Remazol Brillant Blue R (RBBR). Isolate TBB3 (1.70±0.06) and EL2 (1.78±0.08) gave the highest results for ABTS plates with the appearance of greenish halo on around the isolates. Submerged fermentation performed on Isolate TBB3 with the productivity 3.9067 U/ml/day, whereas the laccase activity for Isolate EL2 was much lower (0.2097 U/ml/day). As isolate TBB3 showed higher laccase production, it was subjected to molecular characterization by DNA isolation, PCR amplification and sequencing of ITS region of nuclear ribosomal DNA. After being compared with other sequences in National Center for Biotechnology Information (NCBI database), isolate TBB3 is probably from species Trametes hirsutei. Further research work can be performed on this isolate by upscale the production of laccase in order to meet the demands of the requirement for higher enzyme titer for the bioremediation of textile dyes.

Keywords: bioremediation, dyes, fermentation, laccase

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Authors: H. Boukhatem, L. Djouadi, H. Khalaf, R. M. Navarro, F. V. Ganzalez

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Synthetic organic dyes are used in various industries, such as textile industry, leather tanning industry, paper production, hair dye production, etc. Wastewaters containing these dyes may be harmful to the environment and living organisms. Therefore, it is very important to remove or degrade these dyes before discharging them into the environment. In addition to standard technologies for the degradation and/or removal of dyes, several new specific technologies, the so-called advanced oxidation processes (AOPs), have been developed to eliminate dangerous compounds from polluted waters. AOPs are all characterized by the same chemical feature: production of radicals (•OH) through a multistep process, although different reaction systems are used. These radicals show little selectivity of attack and are able to oxidize various organic pollutants due to their high oxidative capacity (reduction potential of HO• Eo = 2.8 V). Heterogeneous photocatalysis, as one of the AOPs, could be effective in the oxidation/degradation of organic dyes. A major advantage of using heterogeneous photocatalysis for this purpose is the total mineralization of organic dyes, which results in CO2, H2O and corresponding mineral acids. In this study, nanomaterials based on montmorillonite and CuxCd1-xS with different Cu concentration (0.3 < x < 0.7) were utilized for the degradation of the commercial cationic textile dye Methylene blue (MB), used as a model pollutant. The synthesized nanomaterials were characterized by fourier transform infrared (FTIR) and thermogravimetric-differential thermal analysis (TG–DTA). Test results of photocatalysis of methylene blue under UV-Visible irradiation show that the photoactivity of nanomaterials montmorillonite/ CuxCd1-xS increases with the increasing of Cu concentration. The kinetics of the degradation of the MB dye was described with the Langmuir–Hinshelwood (L–H) kinetic model.

Keywords: heterogeneous photocatalysis, methylene blue, montmorillonite, nanomaterial

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