Search results for: hives degradation

Authors: D. Mirauda, M. Greco, P. Moscarelli

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The river flow forecasting represents a crucial point to employ for improving a management policy addressed to the right use of water resources as well as for conjugating prevention and defense actions against environmental degradation. The difficulties occurring during the field activities encourage the development and implementation of operative computation and measuring methods addressed to time reduction for data acquisition and processing maintaining a good level of accuracy. Therefore, the aim of the present work is to test a new entropy based expeditive methodology for the evaluation of the rating curves on three gauged sections with different geometric and morphological characteristics. The methodology requires the choice of only three verticals along the measure section and the sampling of only the maximum velocity. The results underline how in most conditions the rating curves drawn can replace those built with classic methodologies, simplifying thus the procedures of data monitoring and calculation.

Keywords: gauged station, entropic approach, expeditive methodology, rating curves.

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Authors: Chundong Li, V. V. Neshchimenko, M. M. Mikhailov

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The effect of the modification of ZnO powders by ZrO₂, Al₂O₃, TiO₂, SiO₂, CeO₂ and Y₂O₃ nanoparticles with a concentration of 1-30 wt % is investigated by diffuse reflectance spectra within the wavelength range 200 to 2500 nm before and after 100 keV proton and electron irradiation. It has been established that the introduction of nanoparticles ZrO₂, Al₂O₃ enhances the optical stability of the pigments under proton irradiation, but reduces it under electron irradiation. Modifying with TiO₂, SiO₂, CeO₂, Y₂O₃ nanopowders leads to decrease radiation stability in both types of irradiation. Samples modified by 5 wt. % of ZrO₂ nanoparticles have the highest stability of optical properties after proton exposure. The degradation of optical properties under electron irradiation is not high for this concentration of nanoparticles. A decrease in the absorption of pigments modified with nanoparticles proton exposure is determined by a decrease in the intensity of bands located in the UV and visible regions. After electron exposure the absorption bands have in the whole spectrum range.

Keywords: Irradiation, nanopowders, radiation stability, zinc oxide.

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Authors: Mohamed A. Alsharif, Peter A. Wallace, Donald M. Hepburn, Chengke Zhou

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Worldwide, most PILC MV underground cables in use are approaching the end of their design life; hence, failures are likely to increase. This paper studies the electric field and potential distributions within the PILC insulted cable containing common void-defect. The finite element model of the performance of the belted PILC MV underground cable is presented. The variation of the electric field stress within the cable using the Finite Element Method (FEM) is concentrated. The effects of the void-defect within the insulation are given. Outcomes will lead to deeper understanding of the modeling of Paper Insulated Lead Covered (PILC) and electric field response of belted PILC insulted cable containing void defect.

Keywords: MV PILC cables, Finite Element Method /COMSOL Multiphysics, Electric Field Stress, Partial Discharge Degradation.

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Authors: Hazleen Anuar, Nur Aimi Mohd Nasir, Yousuf El-Shekeil

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Durian skin is a newly explores natural fibre potentially reinforced polyolefin for diverse applications. In this work, investigation on the effect of coupling agent, maleic anhydride polypropylene (MAPP) on the mechanical, morphological, and thermal properties of polypropylene (PP) reinforced with durian skin fibre (DSF) was conducted. The presence of 30 wt% DSF significantly reduced the tensile strength of PP-DSF composite. Interestingly, even though the same trend goes to PP-DSF with the presence of MAPP, the reduction is only about 4% relative to unreinforced PP and 18% higher than PP-DSF without MAPP (untreated composite or UTC). The used of MAPP in treated composite (TC) also increased the tensile modulus, flexural properties and degradation temperature. The enhanced mechanical properties are consistent with good interfacial interaction as evidenced under scanning electron microscopy.

Keywords: Durian skin fiber, coupling agent, mechanical properties, thermogravimetry analysis.

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Authors: Alena Sicakova, Adriana Estokova

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Although properly made concrete is inherently a durable material, there are many physical and chemical forces in the environment which can contribute to its deterioration. This paper deals with two aspects of concrete durability in chemical aggressive environment: degradation effect of particular aggressive exposure and role of particular mineral additives. Results of the study of leaching and acid corrosion processes in samples prepared with specific dosage of microsilica and zeolite are given in the paper.

Corrosion progress after 60-day exposition is manifested by increasing rate of both Ca and Si release, what is identified by XRF method. Kind and dosage of additions used in experiment was found to be helpful for stabilization of concrete microstructure.The lowest concentration of mean elements in leachates was observed for mixture V1 (microsilica only) unlike the V2 (microsilica + zeolite). It is surprising in the terms of recommendations of zeolite application for acid exposure. Using microsilica only seems to be more effective.

Keywords: Sustainability, durability, concrete, acid corrosion, leaching.

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Authors: S. Halioui, I. Arikan, M. Schmidt

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Tourism sector in Tunisia faces several problems that range from economic challenges to environmental degradation and social instability. These problems have been intensified because of the increased competition in the tourism market, the political instability, financial crises, and recently terrorism problems have aggravated the situation. As a consequence, a new framework that promotes sustainable tourism in the country and increases its competitiveness is urgently needed. Planning for sustainable tourism sector requires the integration of complex interactions between economic, social and environmental aspects. Sustainable tourism principles can be implemented with the help of Strategic Environmental Assessment (SEA) process, which ensures the full integration of economic, social and environmental considerations while planning for the tourism sector in Tunisia. Results of the paper have broad implications for policy makers and tourism professionals.

Keywords: Sustainable tourism, strategic environmental assessment, tourism planning, policy.

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Authors: Petru V. Notingher, Stefan Busoi, Laurentiu M. Dumitran, Cristina Stancu, Gabriel Tanasescu, Emanuel Balescu

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Degradation of polymeric insulation systems of electrical equipments increases the space charge density and the concentration of electrical dipoles. By consequence, the maximum values and the slopes of absorption/resorption (A/R) currents can change with insulation systems ageing. In this paper, an analysis of the nature of the A/R currents and the importance of their components, especially the polarization current and the current given by the space charge, is presented. The experimental study concerns the A/R currents measurements of plane samples (made from CALMICAGLAS tapes), virgin and thermally accelerated aged. The obtained results show that the ageing process produces an increase of the values and a decrease of shapes of the A/R currents. Finally, the possibility of estimating insulations ageing state and lifetime from A/R currents measurements is discussed.

Keywords: Insulation Systems, Absorption/Resorption Currents, Ageing, Lifetime.

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Authors: Norlin Pauzi, Ahmad R.M. Yahya, Zairossani Nor, Amirul A. Abdullah

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Strain M was isolated from the latex of Hevea brasiliensis that grow in the rubber farm area of Malaysia Rubber Board. Strain M was tentatively identified as Bacillus sp. Strain M demonstrated high protease production at pH 9, and this was suitable to be applied in rubber processing that was in alkaline conditions. The right and suitable proportion to be used in applying supernatant into the latex was two parts of latex and one part of enzyme. In this proportion, the latex was stable throughout the 72 hours of treatment. The potential of strain M to degrade protein in the natural rubber latex was proven with the reduction of 79.3% nitrogen in 24 hours treatment. Centrifugation process of the latex before undergoing the treatment had increased the protein degradation in latex. Although the centrifugation process did not achieve zero nitrogen content, it had improved the performance of protein denaturing in the natural rubber.

Keywords: Hevea brasiliensis, Bacillus sp., protease, latex.

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Authors: K. Kuntanoo, S. Promkotra, P. Kaewkannetra

Abstract:

According to synthetic plastics obtained from petroleum cause some environmental problems. Therefore, degradable plastics become widely used and studied for replacing the synthetic plastic waste. A biopolymer of poly hydroxybutyrate-co-hydroxyvalerate (PHBV) is subgroups of a main kind of polyhydroxyalkanoates (PHAs). Naturally, PHBV is hard, brittle and low flexible while natural rubber (NR) is high elastic latex. Then, they are blended and the biodegradation of the blended PHBV and NR films were examined in soil environment. The results showed that the degradation occurs predominantly in the bulk of the samples. The order of biodegradability was shown as follows: PHBV> PHBV/NR> NR. After biodegradation, the blended films were characterized by appearance analysis such as Scanning Electron Microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). It was found that the biodegradation mainly occurred at the polymer surface.

Keywords: Biodegradation, polyhydroxyalkanoates (PHAs), Polyhydroxybutyrate-co-hydroxyvalerate (PHBV), natural rubber (NR).

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Authors: Mohd. Hasan, Ajmal Kafeel, S. D. Pable

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Ultra-low-power (ULP) circuits have received widespread attention due to the rapid growth of biomedical applications and Battery-less Electronics. Subthreshold region of transistor operation is used in ULP circuits. Major research challenge in the subthreshold operating region is to extract the ULP benefits with minimal degradation in speed and robustness. Process, Voltage and Temperature (PVT) variations significantly affect the performance of subthreshold circuits. Designed performance parameters of ULP circuits may vary largely due to temperature variations. Hence, this paper investigates the effect of temperature variation on device and circuit performance parameters at different biasing voltages in the subthreshold region. Simulation results clearly demonstrate that in deep subthreshold and near threshold voltage regions, performance parameters are significantly affected whereas in moderate subthreshold region, subthreshold circuits are more immune to temperature variations. This establishes that moderate subthreshold region is ideal for temperature immune circuits.

Keywords: Subthreshold, temperature variations, ultralow power.

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Authors: N. Lokeshwari, G Srinikethan, S. G. Joshi, I. Shasikala, B. Srikanth, Bashirahmed, L. Sushma

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Water pollution is a major concern for the pulp and paper industry due to the large quantities of effluents generated. Biodegradation of industrial Lignin and AOX by a fungal isolate identified as Aspergillus flavus, white rot fungi which was isolated from Pulp and Paper effluent was studied in batch flask system with industrial effluent and synthetic solution. The flasks were operated at temperature 32°C at 200rpm for eight days in continuous mode. The average overall pH, Temperature, DO, C.O.D, T.D.S, T.S.S, Lignin, AOX were up to 4.56, 32oC, 4.2mg/l, 104mg/l, 6000 mg/l, 4000mg/l, 575.5mg/l, 2195 mg/l respectively after treatment. The Aspergillus flavus sp was the most effective in the biodegradation of Lignin of pulp industry for 94% at 480nm, AOX for 62% at 510nm and of chemical oxygen demand levels for 45% after 8 days of incubation. The optimal conditions found were 4 pH and 32oC temperature for lignin and AOX degradation.

Keywords: Aspergillus flavus, Lignin, Optimal conditions, Quantification studies.

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Authors: Koo-Yeon Kim, Eun-Hye Kim, Tae-Il Son

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Epidermal Growth Factor (EGF, Mw=6,045) has been reported to have high efficiency of wound repair and anti-wrinkle effect. However, the half-life of EGF in the body is too short to exert the biological activity effectively when applied in free form. Growth Factors can be stabilized by immobilization with carbohydrates from thermal and proteolytic degradation. Low molecular weight chitosan (LMCS) and its derivate prepared by hydrogen peroxide has high solubility. LM6A6DC was successfully prepared as a reactive carbohydrate for the stabilization of EGF by the reactions of LMCS with alkalization, tosylation, azidation and reduction. The structure of LM6A6DC was confirmed by FT-IR, 1H NMR and elementary analysis. For enhancing the stability of free EGF, EGF was attached with LM6A6DC by using water-soluble carbodiimide. EGF-LM6A6DC conjugates did not show any cytotoxicity on the Normal Human Dermal Fibroblast (NHDF) 3T3 proliferation at least under 100 μg/ml. In the result, it was considered that LM6A6DC is suitable to immobilize of growth factor.

Keywords: Epidermal growth factor (EGF), low-molecular-weight chitosan, immobilization.

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Authors: Aleš Florian, Lenka Ševelová, Jaroslav Žák

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Formation of tensile cracks in concrete slabs of rigid pavement can be (among others) the initiation point of the other, more serious failures which can ultimately lead to complete degradation of the concrete slab and thus the whole pavement. Two measures can be used for reliability assessment of this phenomenon - the probability of failure and/or the reliability index. Different methods can be used for their calculation. The simple ones are called moment methods and simulation techniques. Two methods - FOSM Method and Simple Random Sampling Method - are verified and their comparison is performed. The influence of information about the probability distribution and the statistical parameters of input variables as well as of the limit state function on the calculated reliability index and failure probability are studied in three points on the lower surface of concrete slabs of the older type of rigid pavement formerly used in the Czech Republic.

Keywords: Failure, pavement, probability, reliability index, simulation, tensile crack.

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Authors: Meichen Lee, Michael K. H. Leung

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In recent years, visible-light activated photocatalysis has become a major field of intense researches for the higher efficiency of solar energy utilizations. Many attempts have been made on the modification of wide band gap semiconductors, while more and more efforts emphasize on cost-effective synthesis of visible-light activated catalysts. In this work, BiOBr nanoplates with band gap of visible-light range are synthesized through a promising microwave solvothermal method. The treatment time period and temperature dependent BiOBr nanosheets of various particle sizes are investigated through SEM. BiOBr synthesized under the condition of 160°C for 60 mins shows the most uniform particle sizes around 311 nm and the highest surface-to-volume ratio on account of its smallest average particle sizes compared with others. It exhibits the best photocatalytic behavior among all samples in RhB degradation.

Keywords: Microwave solvothermal process, nanoplates, solar energy, visible-light photocatalysis.

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Authors: Sperisa Distantina, Wiratni , Moh. Fahrurrozi, Rochmadi

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The effect of extraction solvent upon properties of carrageenan from Eucheuma cottonii was studied. The distilled water and KOH solution (concentration 0.1- 0.5N) were used as the solvent. Extraction process was carried out in water bath equipped by stirrer with constant speed of 275 rpm with a constant ratio of seaweed weight to solvent volume ( 1:50 g/mL) at 86oC for 45 minutes. The extract was then precipitated in 3 volume of 90% ethanol, oven dried at 60oC. Based on experimental data, alkali significantly influenced yield and properties of extracted carrageenan. The extracted carrageenan was found to have essentially identical FTIR spectra to the reference samples of kappa-carrageenan. Increasing the KOH concentration led to carrageenan containing less sulfate content and intrinsic viscosity. The gel strength increased along with the increasing of KOH concentration. The decreasing of intrinsic viscosity value indicates that a polymer degradation occurs during alkali extraction.

Keywords: gel strength, sulfate, intrinsic viscosity, Eucheumacottonii

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Authors: Ji Nyong Jang, Min Woo Lee, Eun Kyung Kim, Ki Keun Kim, Jae Sung Lim

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Since DVB-RCS has been successively implemented, the mobile communication on the multi-beam satellite communication is attractive attention. And the DVB-RCS standard sets up to support mobility of a RCST. In the case of the spot-beam satellite system, the received signal strength does not differ largely between the center and the boundary of the beam. Thus, the RSS based handoff detection algorithm is not benefit to the satellite system as a terrestrial system. Therefore we propose an Adaptive handoff detection algorithm based on RCST mobility information. Our handoff detection algorithm not only can be used as centralized handoff detection algorithm but also removes uncertainties of handoff due to the variation of RSS. Performances were compared with RSS based handoff algorithm. Simulation results show that the proposed handoff detection algorithm not only achieved better handoff and link degradation rate, but also achieved better forward link spectral efficiency.

Keywords: DVB-RCS, satellite multi-beam handoff, mobility information, handover.

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Authors: S. O. Adeosun, O. S. Sanni

Abstract:

Study on corrosion propensity of welded mild steel- bar in soil media around the coastal area of University of Lagos has been carried out using gravimetric method. Six (6) samples each for welded and unwelded mild steels were cut, their initial weights were recorded and buried in two selected soil. The weight losses of these coupons were measured at regular intervals for a period of six months (180 days).

The corrosiveness of the soil media varied widely depending on the potency level of its constituents. The results revealed that soil in the studied area have marked variations in composition and contents. Soil medium with a lower pH and higher chloride ion concentration aggressively attacked the coupons with the welded steel coupon corroding faster than unwelded one. The medium resistivity to the flow of current is another strong factor affecting corrosion rate.

Keywords: Coastal area, corrosion rate, mild steel, soil media, welds.

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Authors: Shree Laxmi Prashant, Subhash C. Yaragal, K. S. Babu Narayan

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Concrete is found to undergo degradation when subjected to elevated temperatures and loose substantial amount of its strength. The loss of strength in concrete is mainly attributed to decomposition of C-S-H and release of physically and chemically bound water, which begins when the exposure temperature exceeds 100°C. When such a concrete comes in contact with moisture, the cement paste is found rehydrate and considerable amount of strength lost is found to recover. This paper presents results of an experimental program carried out to investigate the effect of recuring on strength gain of OPC concrete specimens subjected to elevated temperatures from 200°C to 800°C, which were subjected to retention time of two hours and four hours at the designated temperature. Strength recoveries for concrete subjected to 7 designated elevated temperatures are compared. It is found that the efficacy of recuring as a measure of strength recovery reduces with increase in exposure temperature.

Keywords: Elevated Temperature, Recuring, Strength Recovery, Compressive strength.

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Authors: Mary L. G. S. Senna, Veruska, C. Dutra, Jr., Keity L. F. Oliveira, Patrícia A. Santos, Alana C. M. Santana

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Environmental impacts are the changes in the physical, chemical or biological properties of natural areas that are most often caused by human actions on the environment and which have consequences for human health, society and the elements of nature. The identification of the environmental impacts is important so that they are mitigated, and above all that the mitigating measures are applied in the area. This work aims to identify the environmental impacts generated in the Praia do Caju area in the city of Palmas/Brazil and show that the lack of structure on the beach intensifies the environmental impacts. The present work was carried out having as parameter, the typologies of exploratory and descriptive and quantitative research through a matrix of environmental impacts through direct observation and registration. The study took place during the holidays from August to December 2016 and photographic record of impacts. From the collected data it was possible to verify that Caju beach suffers constant degradation due to irregular deposition.

Keywords: Leisure, tourism, environmental impacts, Brazil.

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Authors: Petruzzelli G., Pedron F., Rosellini I., Tassi E., Gorini F., Barbafieri M.

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This work involved the use of phytoremediation to remediate an aged soil contaminated with polychlorinated biphenyls (PCBs). At microcosm scale, tests were prepared using soil samples that have been collected in an industrial area with a total PCBs concentration of about 250 μg kg-1. Medicago sativa and Lolium italicum were the species selected in this study that is used as “feasibility test" for full scale remediation. The experiment was carried out with the addition of a mixture of randomly methylatedbeta- cyclodextrins (RAMEB). At the end of the experiment analysis of soil samples showed that in general the presence of plants has led to a higher degradation of most congeners with respect to not vegetated soil. The two plant species efficiencies were comparable and improved by RAMEB addition with a final reduction of total PCBs near to 50%. With increasing the chlorination of the congeners the removal percentage of PCBs progressively decreased.

Keywords: contaminated soil, feasibility test, phytoremediation, polychlorinated biphenyls

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Authors: O. Zennouhi, M. El Mderssa, J. Ibijbijen, E. Bouiamrine, L. Nassiri

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Rangelands and silvopastoral systems of the middle Atlas are under a heavy pressure, which led to pasture degradation, invasion by non-palatable and toxic species and edaphic aridification due to the regression of the global vegetation cover. In this situation, the introduction of multipurpose leguminous shrubs, such as Bituminaria bituminosa (L.) Stirton, commonly known as bituminous clover, could be a promising socio-ecological alternative for the rehabilitation of these degraded areas. The application of biofertilizers like plant growth promoting rhizobacteria especially phosphate solubilizing bacteria (PSB) can ensure a successful installation of this plant in the selected degraded areas. The main objective of the present work is to produce well-inoculated seedlings using the best efficient PSB strains in the greenhouse to increase their ability to resist to environmental constraints once transplanted to the field in the central Middle Atlas.

Keywords: Biofertilizers, Bituminaria bituminosa, phosphate solubilizing bacteria, rehabilitation.

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Authors: B. Tosh, C. R. Routray

Abstract:

Homogeneous graft copolymerization of methyl methacrylate (MMA) onto cellulose was carried out in N, N – dimethyl acetamide/LiCl (DMAc/LiCl) and dimethyl sulfoxide/ paraformaldehyde (DMSO/PF) solvent system taking ceric ammonium nitrate (CAN), benzoyl peroxide (BPO) and tin (II)-2-ethyl hexanoate [Sn(Oct)2] as initiators. Different grafting parameters like graft yield (GY), grafting efficiency (GE) and total conversion of monomer to polymer (TC) were evaluated at different reaction conditions of temperature, time, and variation of the amount of monomer and initiator. The viscosity average molecular weight of grafted PMMA and number of grafts per cellulose chain were also calculated. The products were characterized by FT-IR and 1H-NMR analyses and possible reaction mechanisms were deduced. Thermal degradation of the grafted products was also studied by thermo-gravimetric analysis (TG) and differential thermo-gravimetry (DTG).

Keywords: Grafting, grafting efficiency, homogeneous medium, methyl methacrylate.

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Authors: Nükhet Konuk, N. Gamze Turan, Yüksel Ardalı

Abstract:

Cities play a vital role in the social fabric of countries and in national and regional economic growth worldwide; however, the environmental effects of such growth need to be assessed and managed better. The critical and most immediate problems faced by cities of developing countries are the health impacts of urban pollution that derive from inadequate water, sanitation, drainage and solid waste services, poor urban and industrial waste management, and air pollution. As globalization continues, earth's natural processes transform local problems into international issues. The aim of this study is to provide a broad overview of the pollution from urban wastes and emissions in Turkey which is a developing country. It is aimed to underline the significance of reorganizing the institutional tools in a worldwide perspective in order to generate coherent solutions to urban problems, and to enhance urban quality.

Keywords: Environmental pollution, developing countries, environmental degradation, urban environmental problems.

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Authors: Roberta Ranielle M. de Freitas, Vagner R. Botaro

Abstract:

The relationship between biodegradation and mechanical behavior is fundamental for studies of the application of cellulose acetate films as a possible material for biodegradable packaging. In this work, the biodegradation of cellulose acetate (CA) with DS 2.5 was analyzed in simulated soil. CA films were prepared by casting and buried in the simulated soil. Samples were taken monthly and analyzed, the total time of biodegradation was 6 months. To characterize the biodegradable CA, the DMA technique was employed. The main result showed that the time of exposure to the simulated soil affects the mechanical properties of the films and the values of crystallinity. By DMA analysis, it was possible to conclude that as the CA is biodegraded, its mechanical properties were altered, for example, storage modulus has increased with biodegradation and the modulus of loss has decreased. Analyzes of DSC, XRD, and FTIR were also carried out to characterize the biodegradation of CA, which corroborated with the results of DMA. The observation of the carbonyl band by FTIR and crystalline indices obtained by XRD were important to evaluate the degradation of CA during the exposure time.

Keywords: Biodegradation, cellulose acetate, DMA, simulated soil.

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Authors: Lenka Markovičová, Viera Zatkalíková, Tomasz Garbacz

Abstract:

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, microorganisms and other atmospheric factors.

Keywords: Composites with glass fibres, mechanical properties, polyamides, UV degradation.

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Authors: Walid M. Saad

Abstract:

techniques are examined to overcome the performance degradation caused by the channel dispersion using slow frequency hopping (SFH) with dynamic frequency hopping (DFH) pattern adaptation. In DFH systems, the frequency slots are selected by continuous quality monitoring of all frequencies available in a system and modification of hopping patterns for each individual link based on replacing slots which its signal to interference ratio (SIR) measurement is below a required threshold. Simulation results will show the improvements in BER obtained by DFH in comparison with matched frequency hopping (MFH), random frequency hopping (RFH) and multi-carrier code division multiple access (MC-CDMA) in multipath slowly fading dispersive channels using a generalized bandpass two-path transfer function model, and will show the improvement obtained according to the threshold selection.

Keywords: code division multiple access (CDMA), dynamic channel allocation (DCA), dynamic channel assignment, frequency hopping, matched frequency hopping (MFH).

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Authors: S. Douss, F. Touati, M. Loulou

Abstract:

A design flow of multi-standard down-conversion CMOS mixers for three modern standards: Global System Mobile, Digital Enhanced Cordless Telephone and Universal Mobile Telecommunication Systems is presented. Three active mixer-s structures are studied. The first is based on the Gilbert cell which gives a tolerable noise figure and linearity with a low conversion gain. The second and third structures use the current bleeding and charge injection techniques in order to increase the conversion gain. An improvement of about 2 dB of the conversion gain is achieved without a considerable degradation of the other characteristics. The models used for noise figure, conversion gain and IIP3 used are studied. This study describes the nature of trade-offs inherent in such structures and gives insights that help in identifying which structure is better for given conditions.

Keywords: Active mixer, Radio-frequency transceiver, Multistandardfront end, Gilbert cell, current bleeding, charge injection.

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Authors: V. Iakovoglou, G. N. Zaimes, M. P. Arraiza Bermúdez-Cañete, J. L. García, M. C. Giménez, C. Calderón- Guerrero, F. Ioras, I. Abrudan

Abstract:

A new fast growing trend in tourism is ecotourism, in which tourists visit natural ecosystems under low impact, nonconsumptive and locally oriented activities. Through these activities species and habitats are maintained and typically, underdeveloped regions are emphasized. Ecotourism provides a great alternative, especially for rural and undeveloped area. At the same time, despite its many benefits, it also poses many risks for the naturally protected areas. If ecotourism is practiced improperly degradation and irreversible damages could be the unwanted result. In addition, the lack of MSc programs in the field of Ecotourism in Europe makes it a necessity to be developed. Such an MSc program is being implemented with the lead partner the Technical University of Madrid. The entire partnership has six Universities, seven SMEs and one National Park from seven different countries all over Europe. The MSc will have 10 educational modules that will be available online and will prepare professionals that will be able to implement ecotourism in a sustainable way. Only through awareness and education a sustainable ecotourism will be achieved in the protected areas of Europe.

Keywords: Sustainability, MSc program, protected areas, Erasmus.

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Authors: P. Panichnumsin, B. K. Ahring, A. Nopharatana, P. Chaipresert

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In this study, we illustrated the performance and microbial community of single- and two-phase systems anaerobically co-digesting cassava pulp and pig manure. The results showed that the volatile solid reduction and biogas productivity of two-phase CSTR were 66 ± 4% and 2000 ± 210 ml l-1 d-1, while those of singlephase CSTR were 59 ± 1% and 1670 ± 60 ml l-1 d-1, respectively. Codigestion in two-phase CSTR gave higher 12% solid degradation and 25% methane production than single-phase CSTR. Phylogenetic analysis of 16S rDNA clone library revealed that the Bacteroidetes were the most abundant group, followed by the Clostridia in singlephase CSTR. In hydrolysis/acidification reactor of two-phase system, the bacteria within the phylum Firmicutes, especially Clostridium, Eubacteriaceae and Lactobacillus were the dominant phylogenetic groups. Among the Archaea, Methanosaeta sp. was the exclusive predominant in both digesters while the relative abundance of Methanosaeta sp. and Methanospirillum hungatei differed between the two systems.

Keywords: Anaerobic co-digestion, Cassava pulp, Microbialdiversity, Pig manure.

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Authors: Kapil Kumar, M. G. Dastidar, T. R. Sreekrishnan

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In the present study, an attempt was made to examine the potential of aerobic mixed culture for decolourization of Remazol Black B dye in batch reactors. The effect of pH, temperature, inoculum, initial concentration of dye and initial concentration of glucose was studied with an aim to determine the optimal conditions required for maximum decolourization and degradation. The culture exhibited maximum decolourization ability at pH between 7-8 and at 30°C. A 10% (v/v) inoculum and 1% (w/v) glucose concentration were found to be the optimum for decolourization. A maximum of 98% decolourization was observed at 25 ppm initial concentration of dye after 18 hours of incubation period. At higher dye concentration of 300 ppm, the removal in colour was found to be 75% in 48 hours of incubation period. The results show that the enriched mixed culture from activated sludge has good potential in removal of Remazol Black B dye from wastewater under aerobic conditions.

Keywords: Aerobic conditions, Decolourization, Mixed culture, Remazol Black B.

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