Search results for: organic semiconductor

Authors: Hong Li, Tingxian Li, Xudong Wang, Qinghuo Lin

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Excess-iron (Fe) stresses involved in legume symbiotic nitrogen fixation are not understood. Our objectives were to investigate the tolerance of yardlong-bean plants to soil excess-Fe stress and antagonistic effects of organic amendments and rhizobial inoculants on plant root nodulation and stem ureide formation. The study was conducted in the tropical Hainan Island during 2012-2013. The soil was strongly acidic (pH 5.3±0.4) and highly variable in Fe concentrations(596±79 mg/kg). The treatments were arranged in a split-plot design with three blocks. The treatment effects were significant on root nodulation, stem ureide, amino acids, plant N/Fe accumulation and bean yields (P<0.05). The yardlong-bean stem allantoin, amino acids and nitrate concentrations and relative ureide % declined with high soil Fe concentrations (>300 mg/kg). It was concluded that the co-variance of excess Fe stress could inhibit legume symbiotic N fixation efficiency. Organic amendments and rhizobial inoculants could help improve crop tolerance to excess Fe stress.

Keywords: atmospheric N fixation, root nodulation, soil Fe co-variance, stem ureide, yardlong-bean plants

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Authors: Ziyad Abunada, Abir Al-tabbaa

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The current work is investigating the effectiveness of combined mixed materials mainly modified bentonites and organoclay in treating contaminated groundwater. Sodium bentonite was manufactured with a quaternary amine surfactant, dimethyl ammonium chloride to produce organoclay (OC). Inorgano-organo bentonite (IOB) was produced by intercalating alkylbenzyd-methyl-ammonium chloride surfactant into sodium bentonite and pillared with chlorohydrol pillaring agent. The materials efficiency was tested for both TEX compounds from model-contaminated water and a mixture of organic contaminants found in groundwater samples collected from a contaminated site in the United Kingdom. The sorption data was fitted well to both Langmuir and Freundlich adsorption models reflecting the double sorption model where the correlation coefficient was greater than 0.89 for all materials. The mixed materials showed higher sorptive capacity than individual material with a preference order of X> E> T and a maximum sorptive capacity of 21.8 mg/g was reported for IOB-OC materials for o-xylene. The mixed materials showed at least two times higher affinity towards a mixture of organic contaminants in groundwater samples. Other experimental parameters such as pH and contact time were also investigated. The pseudo-second-order rate equation was able to provide the best description of adsorption kinetics.

Keywords: modified bentobite, groundwater, adsorption, contaminats

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Authors: Hamed A. El-Serehy, Khaled A. Al-Rasheid, Fahad A. Al-Misned

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The composition and distribution of the benthic meiofauna assemblages of the Egyptian coasts along the Red Sea are described in relation to abiotic variables. Sediment samples were collected seasonally from twelve stations chosen along the northern part of the Red Sea to observe the meiofaunal community structure, its temporal distribution and horizontal fluctuation in relation to environmental conditions of the Red Sea marine ecosystem. The meiofaunal assemblage in the area of study was well diversified including 140 taxa. The temperature, salinity, pH, dissolved oxygen, and redox potential were measured at the time of collection. The water content of the sediments, total organic matters and chlorophyll a values were determined, and sediment samples were subjected to granulometric analysis. A total of 10 meiofauna taxa were identified, with the meiofauna being primarily represented by nematodes (on annual average from 42% to 84%), harpacticoids, polycheates and ostracodes; and the meiofauna abundances ranging from 41- to 167 ind. / 10 cm2. The meiofaunal population density fluctuated seasonally with a peak of 192.52 ind. / 10 cm2 during summer at station II. The vertical zonation in the distribution of meiofaunal community was significantly correlated with interstitial water, chlorophyll a and total organic matter values. The present study indicates that the existing of well diversified meiofaunal group which can serve as food for higher trophic levels in the Red Sea interstitial environment.

Keywords: benthos, diversity, meiofauna, Red Sea

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Authors: Z. Ghorannevis, E. Akbarnejad, B. Aghazadeh, M. Ghoranneviss

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Carbon nanotubes (CNTs) modified with semiconductor nanocrystalline particles may find wide applications due to their unique properties. Here Cadmium Sulfide (CdS) nanoparticles were successfully grown on Multi-Walled Carbon Nanotubes (MWNTs) via a magnetron sputtering method for the first time. The CdS/MWNTs sample was characterized with X-ray diffraction (XRD), Field Emission Scanning and High Resolution Transmission Electron Microscopies (SEM/TEM) and four point probe. The obtained images show clearly the decoration of the MWNTs by the CdS nanoparticles, and the XRD measurements indicate the CdS structure as hexagonal type. Moreover, the physical properties of the CdS/MWNTs were compared with the physical properties of the CdS nanoparticles grown on the silicon. Electrical measurements of CdS and CdS/MWNTs reveal that CdS/MWNTs has lower resistivity than the CdS sample which may be due to the higher carrier concentrations.

Keywords: CdS, MWNTs, HRTEM, magnetron sputtering

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Authors: Annisa Ulfah Pristya, Andi Setiawan

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Electricity is the primary requirement today's world, including Indonesia. This is because electricity is a source of electrical energy that is flexible to use. Fossil energy sources are the major energy source that is used as a source of energy power plants. Unfortunately, this conversion process impacts on the depletion of fossil fuel reserves and causes an increase in the amount of CO2 in the atmosphere, disrupting health, ozone depletion, and the greenhouse effect. Solutions have been applied are solar cells, ocean wave power, the wind, water, and so forth. However, low efficiency and complicated treatment led to most people and industry in Indonesia still using fossil fuels. Referring to this Fuel Cell was developed. Fuel Cells are electrochemical technology that continuously converts chemical energy into electrical energy for the fuel and oxidizer are the efficiency is considerably higher than the previous natural source of electrical energy, which is 40-60%. However, Fuel Cells still have some weaknesses in terms of the use of an expensive platinum catalyst which is limited and not environmentally friendly. Because of it, required the simultaneous source of electrical energy and environmentally friendly. On the other hand, Indonesia is a rich country in marine sediments and organic content that is never exhausted. Stacking the organic component can be an alternative energy source continued development of fuel cell is A Microbial Fuel Cell. Microbial Fuel Cells (MFC) is a tool that uses bacteria to generate electricity from organic and non-organic compounds. MFC same tools as usual fuel cell composed of an anode, cathode and electrolyte. Its main advantage is the catalyst in the microbial fuel cell is a microorganism and working conditions carried out in neutral solution, low temperatures, and environmentally friendly than previous fuel cells (Chemistry Fuel Cell). However, when compared to Chemistry Fuel Cell, MFC only have an efficiency of 40%. Therefore, the authors provide a solution in the form of Nano-MFC (Nano Microbial Fuel Cell): Utilization of Carbon Nano Tube to Increase Efficiency of Microbial Fuel Cell Power as an Effective, Efficient and Environmentally Friendly Alternative Energy Source. Nano-MFC has the advantage of an effective, high efficiency, cheap and environmental friendly. Related stakeholders that helped are government ministers, especially Energy Minister, the Institute for Research, as well as the industry as a production executive facilitator. strategic steps undertaken to achieve that begin from conduct preliminary research, then lab scale testing, and dissemination and build cooperation with related parties (MOU), conduct last research and its applications in the field, then do the licensing and production of Nano-MFC on an industrial scale and publications to the public.

Keywords: CNT, efficiency, electric, microorganisms, sediment

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Authors: Alaa Y. Ali, Natalie P. Holmes, John Holdsworth, Warwick Belcher, Paul Dastoor, Xiaojing Zhou

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Multi-layered graphene has been produced under low temperature chemical vapour deposition (CVD) growth conditions by utilizing an organic solvent and polymer film source. Poly(methylmethacrylate) (PMMA) was dissolved in chlorobenzene solvent and used as a drop-cast film carbon source on a quartz slide. A source temperature (T_source) of 180 °C provided sufficient carbon to grow graphene, as identified by Raman spectroscopy, on clean copper foil catalytic surfaces.  Systematic variation of hydrogen gas (H₂) flow rate from 25 standard cubic centimeters per minute (sccm) to 100 sccm and CVD temperature (T_growth) from 400 to 800 °C, yielded graphene films of varying quality as characterized by Raman spectroscopy. The optimal graphene growth parameters were found to occur with a hydrogen flow rate of 75 sccm sweeping the 180 °C source carbon past the Cu foil at 600 °C for 1 min. The deposition at 600 °C with a H₂ flow rate of 75 sccm yielded a 2D band peak with ~53.4 cm^-1 FWHM and a relative intensity ratio of the G to 2D bands (I_G/I_2D) of 0.21. This recipe fabricated a few layers of good quality graphene.

Keywords: graphene, chemical vapor deposition, carbon source, low temperature growth

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Authors: Moussa Hamdan, Abdulati Abdullah

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This paper presents an investigation of the fabrication of the optical devices in terms of their characteristics based on the use of the electromagnetic waves. Planar waveguides are used to examine the field modes (bound modes) and the parameters required for this structure. The modifications are conducted on surface plasmons based waveguides. Simple symmetric dielectric slab structure is used and analyzed in terms of transverse electric mode (TE-Mode) and transverse magnetic mode (TM-Mode. The paper presents mathematical and numerical solutions for solving simple symmetric plasmons and provides simulations of surface plasmons for field confinement. Asymmetric TM-mode calculations for dielectric surface plasmons are also provided.

Keywords: surface plasmons, optical waveguides, semiconductor lasers, refractive index, slab dialectical

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Authors: Rohana Musa, Yuzman Yusoff, Chia Chieu Yin, Hanif Che Lah

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This paper presents the design and characterization of a low power Complementary Metal Oxide Semiconductor (CMOS) process sensor. The design is targeted for implementation using Silterra’s 180 nm CMOS process technology. The proposed process sensor employs a voltage threshold (V_th) extractor architecture for detection of variations in the fabrication process. The process sensor generates output voltages in the range of 401 mV (fast-fast corner) to 443 mV (slow-slow corner) at nominal condition. The power dissipation for this process sensor is 6.3 µW with a supply voltage of 1.8V with a silicon area of 190 µm X 60 µm. The preliminary result of this process sensor that was fabricated indicates a close resemblance between test and simulated results.

Keywords: CMOS process sensor, PVT sensor, threshold extractor circuit, Vth extractor circuit

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Authors: Archana Gupta, Rajesh Kumar

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The chemistry of chalcones has generated intensive scientific studies throughout the world. Especially, interest has been focused on the synthesis and biodynamic activities of chalcones. The blue light transmittance, excellent crystallizability and the two planar rings connected through a conjugated double bond show that chalcone derivatives are superior nonlinear organic compounds. 3-(2-Chloro-6-fluoro¬phen¬yl)-1-(2-thien¬yl) prop-2-en-1-one, 3-(2, 4- Dichlorophenyl) – 1 - (4-methylphenyl) – prop -2-en-1-one, (2E)-3-[4-(methylsulfanyl) phenyl]-1-(4-nitrophenyl) prop-2-en-1-one are some chalcone derivatives exhibiting non linear optical (NLO) properties. NLO materials have been extensively investigated in recent years as they are the key elements for photonic technologies of optical communication, optical interconnect oscillator, amplifier, frequency converter etc. Due to their high molecular hyperpolarizabilities, organic materials display a number of significant NLO properties. Experimental measurements and theoretical calculations on molecular hyperpolarizability β have become one of the key factors in the design of second order NLO materials. Theoretical determination of hyperpolarizability is quite useful both in understanding the relationship between the molecular structure and NLO properties. It also provides a guideline to experimentalists for the design and synthesis of organic NLO materials. Quantum-chemical calculations have made an important contribution to the understanding of the electronic polarization underlying the molecular NLO processes and the establishment of structure–property relationships. In the present investigation, the detailed vibrational analysis of some chalcone derivatives is taken up to understand the correlation of the charge transfer interaction and the NLO activity of the molecules based on density functional theory calculations. The vibrational modes contributing toward the NLO activity have been identified and analyzed. Rather large hyperpolarizability derived by theoretical calculations suggests the possible future use of these compounds for non-linear optical applications. The study suggests the importance of π - conjugated systems for non-linear optical properties and the possibility of charge transfer interactions. We hope that the results of the present study of chalcone derivatives are of assistance in development of new efficient materials for technological applications.

Keywords: hyperpolarizability, molecular structure, NLO material, quantum chemical calculations

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Authors: Refal Hussain, Saifuddin M. Nomanbhay

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Glycerol is a valuable raw material for the production of industrially useful metabolites. Among many promising applications for the use of glycerol is its bioconversion to high value-added compounds, such as bioethanol through microbial fermentation. Bioethanol is an important industrial chemical with emerging potential as a biofuel to replace vanishing fossil fuels. The yield of liquid fuel in this process was greatly influenced by various parameters viz, temperature, pH, glycerol concentration, organic concentration, and agitation speed were considered. The present study was undertaken to investigate optimum parameters for bioethanol production from raw glycerol by immobilized mutant Escherichia coli (E.coli) (ATCC11505) strain on chitosan cross linked glutaraldehyde optimized by Taguchi statistical method in shake flasks. The initial parameters were set each at four levels and the orthogonal array layout of L16 (45) conducted. The important controlling parameters for optimized the operational fermentation was temperature 38 °C, medium pH 6.5, initial glycerol concentration (250 g/l), and organic source concentration (5 g/l). Fermentation with optimized parameters was carried out in a custom fabricated shake flask. The predicted value of bioethanol production under optimized conditions was (118.13 g/l). Immobilized cells are mainly used for economic benefits of continuous production or repeated use in continuous as well as in batch mode.

Keywords: bioethanol, Escherichia coli, immobilization, optimization

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Authors: Luh Putu T. Darmayanti, A. A. Duwipayana, I. Nengah K. Putra, Nyoman S. Antara

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Tabah Bamboo (Gigantochloa nigrociliata (Buese) Kurz) is the indigenous bamboo species which grows in District of Pupuan, Tabanan at Province of Bali. Compared to the others, this shoot has low concentration of hydrocyanide acid (HCN). However, as found for almost of bamboo shoot, its seasonal availability, perishable in nature, and short-lived. This study aimed to gather information about total of lactic acid bacteria (LAB), pH, total acidity, HCN content, detection of LAB’s type involved during fermentation, and organic acids’ profiles of fermented pickles of Tabah bamboo shoot. The pickle was made by natural fermentation with 6 % salt concentration and fermentation conducted for 13 days. The result showed during the fermentation time, in the fourth day we found LAB’s number was highest as much as 72 x 107 CFU/ml and the lowest pH was 3.09. We also found decreasing in HCN from 37.8 ppm at the beginning to 20.52 ppm at the end of fermentation process. The total number of indigenous LAB isolated from the pickle are 48 strains we found 18 out of these had rod shape. For the preliminary study, all of the LAB with rod shape were detected by PCR as member of Lactobacillus spp., in which 17 strains detected as L. plantarum. The organic acids detected during the fermentation were lactic acid with the highest concentration was 0.0546 g/100 g and small amount of acetic acid.

Keywords: fermentation, LAB, pickle, Tabah Bamboo shoot

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Authors: Oladejo S. O, Tomori W. B, Adebayo A. O

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The main objective of this research is to identify the geochemical and mineralogical characteristics potential of unexplored tailings around the gold deposit region using spatial statistics and map modeling. Some physicochemical parameters such as pH, redox potential, electrical conductivity, cation exchange capacity, total organic carbon, total organic matter, residual humidity, Cation exchange capacity, and particle size were determined from both the mine drains and tailing samples using standard methods. The physicochemical parameters of tailings ranges obtained were pH (6.0 – 7.3), Eh (−16 - 95 Mev), EC (49 - 156 µS/cm), RH (0.20-2.60%), CEC (3.64-6.45 cmol/kg), TOC (3.57-18.62%), TOM (6.15-22.93%). The geochemical oxide composition were identified using Proton Induced X-ray emission and the results indicated that SiO2>Al2O3>Fe2O3>TiO2>K2O>MgO>CaO>Na2O> P2O5>MnO>Cr2O3>SrO>K2O>P2O5. The major mineralogical components in the tailing samples were determined by quantitative X-ray diffraction techniques using the Rietveld method. Geostatistical relationships among the known points were determined using ArcGIS 10.2 software to interpolate mineral concentration with respect to the study area. The Rietveld method gave a general Quartz value of 73.73-92.76%, IImenite as 0.38-4.77%, Kaolinite group as 3.19-20.83%, Muscovite as 0.77-11.70% with a trace of other minerals. The high percentage of quartz is an indication of a sandy environment with a loose binding site.

Keywords: tailings, geochemical, mineralogy, spatial

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Authors: Gadisa Demie, Mesele Negash, Zerihun Asrat, Lojka Bohdan

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Deforestation and forest degradation in the tropics have led to significant carbon (C) emissions. Agroforestry (AF) is a suitable land-use option for tackling such declines in ecosystem services, including climate change mitigation. However, it is unclear how biomass models, AF practices, and socio-ecological factors determine these roles, which hinders the implementation of climate change mitigation initiatives. This study aimed to estimate the ecosystem C stocks of the studied AF practices in relation to socio-ecological variables in central Ethiopia. Out of 243 AF farms inventoried, 108 were chosen at random from three AF practices to estimate their biomass and soil organic carbon. A total of 432 soil samples were collected from 0–30 and 30–60 cm soil depths; 216 samples were taken for each soil organic carbon fraction (%C) and bulk density computation. The study found that the currently developed allometric equations were the most accurate to estimate biomass C for trees growing in the landscape when compared to previous models. The study found higher overall biomass C in woodlots (165.62 Mg ha-¹) than in homegardens (134.07 Mg ha-¹) and parklands (19.98 Mg ha-¹). Conversely, overall, SOC was higher for homegardens (143.88 Mg ha-¹), but lower for parklands (53.42 Mg ha-¹). The ecosystem C stock was comparable between homegardens (277.95 Mg ha-¹) and woodlots (275.44 Mg ha-¹). The study found that elevation, wealthy levels, AF farm age, and size have a positive and significant (P < 0.05) effect on overall biomass and ecosystem C stocks but non-significant with slope (P > 0.05). Similarly, SOC increased with increasing elevation, AF farm age, and wealthy status but decreased with slope and non-significant with AF farm size. The study also showed that species diversity had a positive (P <0.05) effect on overall biomass C stocks in homegardens. The overall study highlights that AF practices have a great potential to lock up more carbon in biomass and soils; however, these potentials were determined by socioecological variables. Thus, these factors should be considered in management strategies that preserve trees in agricultural landscapes in order to mitigate climate change and support the livelihoods of farmers.

Keywords: agricultural landscape, biomass, climate change, soil organic carbon

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Authors: Alejandro Cittadino, David Allende

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Landfilling of municipal solid waste is a common waste management practice in Argentina as in many parts of the world. There is extensive scientific literature on the potential negative effects of landfill leachates on the environment, so it’s necessary to be rigorous with the control and monitoring systems. Due to the specific municipal solid waste composition in Argentina, local landfill leachates contain large amounts of organic matter (biodegradable, but also refractory to biodegradation), as well as ammonia-nitrogen, small trace of some heavy metals, and inorganic salts. In order to investigate the surface water quality in the Reconquista river adjacent to the Norte III landfill, water samples both upstream and downstream the dumpsite are quarterly collected and analyzed for 43 parameters including organic matter, heavy metals, and inorganic salts, as required by the local standards. The objective of this study is to apply a water quality index that considers the leachate characteristics in order to determine the quality status of the watercourse through the landfill. The water pollution index method has been widely used in water quality assessments, particularly rivers, and it has played an increasingly important role in water resource management, since it provides a number simple enough for the public to understand, that states the overall water quality at a certain location and time. The chosen water quality index (ICA) is based on the values of six parameters: dissolved oxygen (in mg/l and percent saturation), temperature, biochemical oxygen demand (BOD5), ammonia-nitrogen and chloride (Cl-) concentration. The index 'ICA' was determined both upstream and downstream the Reconquista river, being the rating scale between 0 (very poor water quality) and 10 (excellent water quality). The monitoring results indicated that the water quality was unaffected by possible leachate runoff since the index scores upstream and downstream were ranked in the same category, although in general, most of the samples were classified as having poor water quality according to the index’s scale. The annual averaged ICA index scores (computed quarterly) were 4.9, 3.9, 4.4 and 5.0 upstream and 3.9, 5.0, 5.1 and 5.0 downstream the river during the study period between 2014 and 2017. Additionally, the water quality seemed to exhibit distinct seasonal variations, probably due to annual precipitation patterns in the study area. The ICA water quality index appears to be appropriate to evaluate landfill impacts since it accounts mainly for organic pollution and inorganic salts and the absence of heavy metals in the local leachate composition, however, the inclusion of other parameters could be more decisive in discerning the affected stream reaches from the landfill activities. A future work may consider adding to the index other parameters like total organic carbon (TOC) and total suspended solids (TSS) since they are present in the leachate in high concentrations.

Keywords: landfill, leachate, surface water, water quality index

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Authors: A. Pourahmad, Sh. Gharipour

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The present work describes the preparation and characterization of nanosized SiO₂@PbS core-shell particles by using a simple wet chemical route. This method utilizes silica spheres formation followed by successive ionic layer adsorption and reaction method assisted lead sulphide shell layer formation. The final product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis spectroscopic, infrared spectroscopy (IR) and transmission electron microscopy (TEM) experiments. The morphological studies revealed the uniformity in size distribution with core size of 250 nm and shell thickness of 18 nm. The electron microscopic images also indicate the irregular morphology of lead sulphide shell layer. The structural studies indicate the face-centered cubic system of PbS shell with no other trace for impurities in the crystal structure.

Keywords: core-shell, nanostructure, semiconductor, optical property, XRD

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Authors: Amal Aljohani, Ahmed Iraqi

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Emitting materials with thermally activated delayed fluorescence (TADF) properties as the third generation of organic light-emitting diodes (OLEDs) have received much attention as a modern class of highly efficient emitters because such properties enable the harvesting of both singlet and triplet excitons in EL applications without the doping with complexes of scarce noble metals such as platinum and iridium. Improved molecular design of TADF molecules and applied materials exhibiting internal electroluminescence (EL) with quantum efficiencies of nearly 100% has been achieved being. A2B3 hyperbranched polymers based on new derivatives containing silane core units serving as host materials for thermally activated delayed fluorescence (TADF) guest molecules have been designed and synthesized through several steps, including the synthesis of tetrakis(4-bromophenyl)silane, bis(4-(9H-carbazol-9-yl)phenyl)bis(4-bromophenyl)silane,bis(4-(9H-carbazol-9 yl)phenyl)bis(4-methoxyphenyl)silane and bis(4-(9H-carbazol-9-yl)phenyl)bis(4hydroxyphenyl)silane. This monomer has been used successfully used along with 1,1,1-tri-(p-tosyloxymethyl)-propane to prepare A2B3 hyperbranched polymers via step-growth polymerization. The characterization and the properties of these new host polymers will be presented and discussed in this contribution.

Keywords: carbazole, organic light emitting diodes, thermally activated delayed fluorescence, donor-acceptor, host and guest interaction

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Authors: F. A. Ogundolie, F. Okogue, D. V. Adegunloye

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Greywater samples were obtained from three restaurants in the Federal University of Technology; Akure coded SSR, MGR and GGR. Fungi isolates obtained include Rhizopus stolonifer, Aspergillus niger, Mucor mucedo, Aspergillus flavus, Saccharomyces cerevisiae. Of these fungi isolates obtained, R. stolonifer, A. niger and A. flavus showed significant degradation ability on grey water and was used for this research. A simple bioreactor was constructed using biodegradation process in purification of waste water samples. Waste water undergoes primary treatment; secondary treatment involves the introduction of the isolated organisms into the waste water sample and the tertiary treatment which involved the use of filter candle and the sand bed filtration process to achieve the end product without the use of chemicals. A. niger brought about significant reduction in both the bacterial load and the fungi load of the greywater samples of the three respective restaurants with a reduction of (1.29 × 108 to 1.57 × 102 cfu/ml; 1.04 × 108 to 1.12 × 102 cfu/ml and 1.72 × 108 to 1.60 × 102 cfu/ml) for bacterial load in SSR, MGR and GGR respectively. Reduction of 2.01 × 104 to 1.2 × 101; 1.72 × 104 to 1.1 × 101, and 2.50 × 104 to 1.5 × 101 in fungi load from SSR, MGR and GGR respectively. Result of degradation of these selected waste water by the fungi showed that A. niger was probably more potent in the degradation of organic matter and hence, A. niger could be used in the treatment of wastewater.

Keywords: Aspergillus niger, greywater, bacterial, fungi, microbial load, bioreactor, biodegradation, purification, organic matter and filtration

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Authors: Min-Hao Wang, Shih-Chih Chen

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Recently, the merits such as simple structure, low power consumption, and compatibility with complementary metal oxide semiconductor (CMOS) process give an advantage of resistive random access memory (RRAM) as a promising candidate for the next generation memory， hafnium dioxide (HfO2) has been widely studied as an oxide layer material, but the use of copper (Cu) as both top and bottom electrodes has rarely been studied. In this study, radio frequency sputtering was used to deposit the intermediate layer HfO₂, and electron beam evaporation was used. For the upper and lower electrodes (cu), using different AR: O ratios, we found that the control of the metal filament will make the filament widely distributed, causing the current to rise to the limit current during Reset. However, if the flow ratio is controlled well, the ON/OFF ratio can reach 104, and the set voltage is controlled below 3v.

Keywords: RRAM, metal filament, HfO₂, Cu electrode

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Authors: H. Beisch, J. Marx, S. Garlof, R. Shvets, I. I. Grygorchak, A. Kityk, B. Fiedler

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Carbon materials, especially three-dimensional carbon foams, show very high potential in the application as electrode material for energy storage systems such as batteries and supercapacitors with unique fast charging and discharging times. Regarding their high specific surface areas (SSA) high specific capacities can be reached. Globugraphite is a newly developed carbon foam with an interconnected globular carbon morphology. Especially, this foam has a statistically distributed hierarchical pore structure resulting from the manufacturing process based on sintered ceramic templates which are synthetized during a final chemical vapor deposition (CVD) process. For morphology characterization scanning electron (SEM) and transmission electron microscopy (TEM) is used. In addition, the SSA is carried out by nitrogen adsorption combined with the Brunauer–Emmett–Teller (BET) theory. Electrochemical measurements in organic and inorganic electrolyte provide high energy densities and power densities resulting from ion absorption by forming an electrochemical double layer. All values are summarized in a Ragone Diagram. Finally, power densities up to 833 W/kg and energy densities up to 48 Wh/kg could be achieved. The corresponding SSA is between 376 m²/g and 859 m²/g. For organic electrolyte a specific capacity of 71 F/g at a density of 20 mg/cm³ was achieved.

Keywords: BET, CVD process, electron microscopy, Ragone diagram

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Authors: S. Yussuf Abdulmaliq

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Experiment was conducted for two years (2013 and 2014) at Ibrahim Badamasi Babangida University, Lapai, Teaching and Research Farm to study the effects of soil organic amendment types and rates on soil chemical fertility improvement, growth and yield of Amarathus cruentus in the southern guinea savannah, lapai, Niger state, Nigeria. Soil and manure samples were collected and analysed for physical and chemical components. The experiments were laid out in 3 x 4 factorial in a randomized complete block design (RCBD). Consisting of three (3) levels of soil amendment types (Poultry manure, goat manure and cowdung) and four (4) levels of amendment rates (0, 6, 12 and 18 t ha-1). Data collected include plant height/plant (cm), number of leaves/plant, leaf area/ plant (cm2) at 2, 4, 6 and 8WAT, fresh vegetable yield/plant, fresh vegetable yield/plot and fresh vegetable yield in tons ha-1. The result obtained showed that, Amaranthus cruentus height, number of leaves and leaf area were not significantly affected by the type of organic amendment and rates at 2WAT in 2013 and 2014 cropping seasons. However, at 4, 6 and 8 WAT, significant differences were observed among the types of amendment and their rates. Application of poultry manure as soil amendment supported taller, large number of leaves and wider leaf area, and higher marketable vegetable yield in 2013 and 2014 cropping seasons (Pα 0.05) which was closely followed by goat manure in the two (2) cropping seasons. In addition, the application of 18 t ha-1 was superior to 12, 6 and the control by producing tallest amaranthus plants, higher number of leaves, wider leaf area and higher marketable vegetable yield in 2013 and 2014 cropping seasons (Pα 0.05). In conclusion, the use of 18 t ha-1poultry manure is therefore recommended as soil amendment for Amaranthus cruentus in southern guinea savannah of Nigeria.

Keywords: Amaranthus cruentus, cowdung, goat manure, poultry manure, soil amendment

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Authors: Mustapha Bouhoun Ali, Ahmed Yacine Badjah Hadj Ahmed, Mouloud Attou, Abdel Hamid Elias, Mohamed Amine Didi

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The extraction of uranium(VI) from aqueous solutions has been investigated using 1-hydroxyhexadecylidene-1,1-diphosphonic acid (HHDPA) and 1-hydroxydodecylidene-1,1-diphosphonic acid (HDDPA), which were synthesized and characterized by elemental analysis and by FT-IR, 1H NMR, 31P NMR spectroscopy. In this paper, we propose a tentative assignment for the shifts of those two ligands and their specific complexes with uranium(VI). We carried out the extraction of uranium(VI) by HHDPA and HDDPA from [carbon tetrachloride + 2-octanol (v/v: 90%/10%)] solutions. Various factors such as contact time, pH, organic/aqueous phase ratio and extractant concentration were considered. The optimum conditions obtained were: contact time = 20 min, organic/aqueous phase ratio = 1, pH value = 3.0 and extractant concentration = 0.3M. The extraction yields are more significant in the case of the HHDPA which is equipped with a hydrocarbon chain, longer than that of the HDDPA. Logarithmic plots of the uranium(VI) distribution ratio vs. pHeq and the extractant concentration showed that the ratio of extractant to extracted uranium(VI) (ligand/metal) is 2:1. The formula of the complex of uranium(VI) with the HHDPA and the DHDPA is UO2(H3L)2 (HHDPA and DHDPA are denoted as H4L). A spectroscopic analysis has showed that coordination of uranium(VI) takes place via oxygen atoms.

Keywords: liquid-liquid extraction, uranium(VI), 1-hydroxyalkylidene-1, 1-diphosphonic acids, HHDPA, HDDPA, aqueous solution

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Authors: Boudjedra Abderrahim, Toumi Salah, Boutalbi Mostefa, Frihi Mohammed

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Nowadays, using the advancement of technology in semiconductor device fabrication, many transistors can be integrated to a single chip (VLSI). Although the growth chip density potentially eases systems-on-chip (SoCs) integrating thousands of processing element (PE) such as memory, processor, interfaces cores, system complexity, high-performance interconnect and scalable on-chip communication architecture become most challenges for many digital and embedded system designers. Networks-on-chip (NoCs) becomes a new paradigm that makes possible integrating heterogeneous devices and allows many communication constraints and performances. In this paper, we are interested for good performance and low area for implementation and a behavioral modeling of network on chip mesh topology design using VHDL hardware description language with performance evaluation and FPGA implementation results.

Keywords: design, implementation, communication system, network on chip, VHDL

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Authors: Imran, Murad Ali Rahat

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One of the factors affecting crop production and nutrient availability is acidic stress. The most important element decreasing under acidic stress conditions is phosphorus deficiency, which results in stunted growth and yield because of inefficient nutrient cycling. At the Agriculture Research Institute Mingora Swat, Pakistan, tests were carried out for the first time throughout the course of two consecutive summer seasons in 2016 (year 1) and 2017 (year 2) with the goal of increasing crop productivity and nutrient availability under acidic stress. Three organic supplies (peach nano-black carbon, compost, and dry-based peach wastes), three phosphorus rates, and two advantageous microorganisms (Trichoderma and PSB) were incorporated in the experimental treatments. The findings showed that, in conditions of acid stress, peach organic sources had a significant impact on yield and yield components. The application of nano-black carbon produced the greatest thousand seed weight of 164.6 g among organic sources, however the use of phosphorus solubilizing bacteria (PSB) for seed inoculation increased the thousand seed weight of beneficial microbes when compared to Trichoderma soil application. The thousand seed weight was significantly impacted by the quantities of phosphorus. The treatment of 100 kg P ha-1 produced the highest thousand seed weight (167.3 g), which was followed by 75 kg P ha-1 (162.5 g). Compost amendments provided the highest seed yield (2,140 kg ha-1) and were comparable to the application of nano-black carbon (2,120 kg ha-1). With peach residues, the lowest seed output (1,808 kg ha-1) was observed.Compared to seed inoculation with PSB (1,913 kg ha-1), soil treatment with Trichoderma resulted in the maximum seed production (2,132 kg ha-1). Applying phosphorus to the soybean crop greatly increased its output. The highest seed yield (2,364 kg ha-1) was obtained with 100 kg P ha-1, which was comparable to 75 kg P ha-1 (2,335 kg ha-1), while the lowest seed yield (1,569 kg ha-1) was obtained with 50 kg P ha-1. The average values showed that compared to control plots (3.3 g kg-1), peach organic sources produced greatest SOC (10.0 g kg-1). Plots with treated soil had a maximum soil P of 19.7 mg kg-1, while plots under stress had a maximum soil P of 4.8 mg kg-1. While peach compost resulted in the lowest soil P levels, peach nano-black carbon yielded the highest soil P levels (21.6 mg kg-1). Comparing beneficial bacteria with PSB to Trichoderma (18.3 mg/kg-1), the former also shown an improvement in soil P (21.1 mg kg-1). Regarding P treatments, the application of 100 kg P per ha produced significantly higher soil P values (26.8 mg /kg-1), followed by 75 kg P per ha (18.3 mg /kg-1), and 50 kg P ha-1 produced the lowest soil P values (14.1 mg /kg-1). Comparing peach wastes and compost to peach nano-black carbon (13.7 g kg-1), SOC rose. In contrast to PSB (8.8 g kg-1), soil-treated Trichoderma was shown to have a greater SOC (11.1 g kg-1). Higher among the P levels.

Keywords: acidic stress, trichoderma, beneficial microbes, nano-black carbon, compost, peach residues, phosphorus, soybean

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Authors: Janjira Triped, Wipada Sanongraj, Wipawee Khamwichit

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The research work covered in this study includes the morphological structure and optical properties of TiO2-coated silk fibroin (SF) filters at 2.5% wt. TiO2/vol. PVA solution. SEM micrographs revealed the fibrous morphology of the TiO2-coated SF filters. An average diameter of the SF fiber was estimated to be approximately 10µm. Also, it was confirmed that TiO2 can be adhered more on SF filter surface at higher TiO2 dosages. The activity of semiconductor materials was studied by UV-VIS spectrophotometer method. The spectral data recorded shows the strong cut off at 390 nm. The calculated band-gap energy was about 3.19 eV. The photocatalytic activity of the filter was tested for gaseous formaldehyde removal in a modeling room with the total volume of 2.66 m3. The highest removal efficiency (54.72 ± 1.75%) was obtained at the initial formaldehyde concentration of about 5.00 ± 0.50ppm.

Keywords: photocatalytic oxidation process, formaldehyde (HCHO), silk fibroin (SF), titanium dioxide (TiO2)

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Authors: Misbah Khan, Jian Wen, Muhammad Asif Shakoori

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The Organic Rankine Cycle (ORC) plays an important role in converting low-temperature heat sources into electrical power by using refrigerants as working fluids. The thermophysical properties of working fluids are essential for designing ORC. HFO-1336mzz(Z) (cis-1,1,1,4,4,4-hexafluoro-2-butene) considered as working fluid and have almost 99% low GWP and relatively same thermophysical properties used as a replacement of HFC-245fa (1,1,1,3,3-pentafluoro-propane). The environmental, safety, healthy and thermophysical properties of HFO-1336mzz(Z) are needed to use it in a practical system. In this paper, Molecular dynamics simulations were used to investigate the Homogeneous condensation, thermophysical and structural properties of HFO-1336mzz(Z) and HFC-245fa. The effect of various temperatures and pressures on thermophysical properties and condensation was extensively investigated. The liquid densities and isobaric heat capacities of this refrigerant was simulated at 273.15K to 353.15K temperatures and pressure0.5-4.0MPa. The simulation outcomes were compared with experimental data to validate our simulation method. The mean square displacement for different temperatures was investigated for dynamical analysis. The variations in potential energies and condensation rate were simulated to get insight into the condensation process. The radial distribution function was simulated at the micro level for structural analysis and revealed that the phase transition of HFO-1336mzz(Z) did not affect the intramolecular structure.

Keywords: homogenous condensation, refrigerants, molecular dynamics simulations, organic rankine cycle

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Authors: Tatiana V. Melnikova, Lyudmila P. Polyakova, Alla A. Oudalova

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As a result of environmental pollution, the production of agriculture and foodstuffs inevitably contain residual amounts of Persistent Organic Pollutants (POP). The special attention must be given to organic pollutants, including various organochlorinated pesticides (OCP). Among priorities, OCP is DDT (and its metabolite DDE), alfa-HCH, gamma-HCH (lindane). The control of these substances spends proceeding from requirements of sanitary norms and rules. During too time often is lost sight of that the primary product can pass technological processing (in particular irradiation treatment) as a result of which transformation of physicochemical forms of initial polluting substances is possible. The goal of the present work was to study the OCP radiation degradation at a various gamma-radiation dosimetric characteristics. The problems posed for goal achievement: to evaluate the content of the priority of OCPs in food; study the character the degradation of OCP in model solutions (with micro concentrations commensurate with the real content of their agricultural and food products) depending upon dosimetric characteristics of gamma-radiation. Qualitative and quantitative analysis of OCP in food and model solutions by gas chromatograph Varian 3400 (Varian, Inc. (USA)); chromatography-mass spectrometer Varian Saturn 4D (Varian, Inc. (USA)) was carried out. The solutions of DDT, DDE, alpha- and gamma- isomer HCH (0.01, 0.1, 1 ppm) were irradiated on "Issledovatel" (60Co) and "Luch - 1" (60Co) installations at a dose 10 kGy with a variation of dose rate from 0.0083 up to 2.33 kGy/sec. It was established experimentally that OCP residual concentration in individual samples of food products (fish, milk, cereal crops, meat, butter) are evaluated as 10-1-10-4 mg/kg, the value of which depends on the factor-sensations territory and natural migration processes. The results were used in the preparation of model solutions OCP. The dependence of a degradation extent of OCP from a dose rate gamma-irradiation has complex nature. According to our data at a dose 10 kGy, the degradation extent of OCP at first increase passes through a maximum (over the range 0.23 – 0.43 Gy/sec), and then decrease with the magnification of a dose rate. The character of the dependence of a degradation extent of OCP from a dose rate is kept for various OCP, in polar and nonpolar solvents and does not vary at the change of concentration of the initial substance. Also in work conditions of the maximal radiochemical yield of OCP which were observed at having been certain: influence of gamma radiation with a dose 10 kGy, in a range of doses rate 0.23 – 0.43 Gy/sec; concentration initial OCP 1 ppm; use of solvent - 2-propanol after preliminary removal of oxygen. Based on, that at studying model solutions of OCP has been established that the degradation extent of pesticides and qualitative structure of OCP radiolysis products depend on a dose rate, has been decided to continue researches radiochemical transformations OCP into foodstuffs at various of doses rate.

Keywords: degradation extent, dosimetric characteristics, gamma-radiation, organochlorinated pesticides, persistent organic pollutants

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Authors: Fatima Zohra Ibn Majdoub Hassani, Ivan Lavandera, Joseph Kreit

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This study explored the effects of different organic solvents, temperature, and the amount of glycerol on the alcohol dehydrogenase (ADH)-catalysed stereoselective reduction of different ketones. These conversions were then analyzed by gas chromatography. It was found that when the amount of deep eutectic solvents (DES) increases, it can improve the stereoselectivity of the enzyme although reducing its ability to convert the substrate into the corresponding alcohol. Moreover, glycerol was found to have a strong stabilizing effect on the ADH from Ralstonia sp. (E. coli/ RasADH). In the case of organic solvents, it was observed that the best conversions into the alcohols were achieved with DMSO and hexane. It was also observed that temperature decreased the ability of the enzyme to convert the substrates into the products and also affected the selectivity. In addition to that, the recycling of DES up to three times gave good conversions and enantiomeric excess results and glycerol showed a positive effect in the stability of various ADHs. Using RasADH, a good conversion and enantiomeric excess into the S-alcohol were obtained. It was found that an enhancement of the temperature disabled the stabilizing effect of glycerol and decreased the stereoselectivity of the enzyme. However, for other ADHs a temperature increase had an opposite positive effect, especially with ADH-T from Thermoanaerobium sp. One of the objectives of this study was to see the effect of cofactors such as NAD(P) on the biocatlysis activities of ADHs.

Keywords: alcohol dehydrogenases, DES, gas chromatography, RasADH

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Authors: Omasan Urhie Urhie, Adenipekun C. O, Eke W., Ogwu K., Erinle K. O

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Polychlorinated Biphenyls (PCBs) are Persistent organic pollutants (POPs) that are very toxic; they possess ability to accumulate in soil and in human tissues hence resulting in health issues like birth defect, reproductive disorder and cancer. The air is polluted by PCBs through volatilization and dispersion; they also contaminate soil and sediments and are not easily degraded. Soil samples were collected from a depth of 0-15 cm from three substations (Warri, Ughelli and Ibadan) of Power Holding Company of Nigeria (PHCN) where old transformers were dumped in Nigeria. Extraction and cleanup of soil samples were conducted using Accelerated Solvent Extraction (ASE) with Pressurized Liquid extraction (PLE). The concentration of PCBs was determined using gsas chromatography/mass spectrometry (GC/MS). Mean total PCB concentrations in the soil samples increased in the order Ughelli ˂ Ibadan˂ Warri, 2.457757ppm Ughelli substation 4.198926ppm, for Ibadan substation and 14.05065ppm at Warri substation. In the Warri samples, PCB-167 was the most abundant at about 30% (4.28086ppm) followed by PCB-157 at about 20% (2.77871), of the total PCB concentrations (14.05065ppm). Of the total PCBs in the Ughelli and Ibadan samples, PCB-156 was the most abundant at about 44% and 40%, respectively. This study provides a baseline report on the presence of PCBs in the vicinity of abandoned electrical power facilities in different cities in Nigeria.

Keywords: polychlorintated biphenyls, persistent organic pollutants, soil, transformer

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Authors: A. A. Vasin, N. V. Klassen, A. M. Likhter

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Water suspensions of in-organic (metals and oxides) and organic nano-objects (chitozan and collagen) were subjected to the treatment of direct and alternative electrical fields. In addition to quasi-periodical spatial patterning resonance-like performance of spatial distributions of these suspensions has been found at low frequencies of alternating electrical field. These resonances are explained as the result of creation of equilibrium states of groups of charged nano-objects with opposite signs of charges at the interparticle distances where the forces of Coulomb attraction are compensated by the repulsion forces induced by relatively negative polarization of hydrated regions surrounding the nanoparticles with respect to pure water. The low frequencies of these resonances are explained by comparatively big distances between the particles and their big masses with t\respect to masses of atoms constituting molecules with high resonance frequencies. These new resonances open a new approach to detailed modeling and understanding of mechanisms of the influence of electrical fields on the functioning of internal organs of living organisms at the level of cells and neurons.

Keywords: bio-polymers, chitosan, collagen, nanoparticles, coulomb attraction, polarization repulsion, periodical patterning, electrical low frequency resonances, transformations

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Authors: S. K. Gali

Abstract:

Spentwash, An effluent of distillery is an environmental pollutant because of its high load of pollutants (pH: 2-4; BOD>40,000 mg/l, COD>100,000mg/l and TDS >70,000mg/l). But However, after subjecting it to primary treatment (bio-methanation), Its pollutant load gets drastically reduced (pH: 7.5-8.5, BOD<10,000 mg/l) and could be disposed off safely as a source of organic matter and plant nutrients for crop production. With the consent of State Pollution Control Board, the distilleries in Karnataka are taking up ‘one time controlled land application’ of bio-methanated spentwash in farmers’ fields. A monitoring study was undertaken in Belgaum district of Karnataka State with an objective of studying the effect of land application of bio-methanated spent wash of a distillery on soil properties and crop growth. The treated spentwash was applied uniformly to the fallow dry lands in different farmers’ fields during summer, 2012 at recommended rate (based on nitrogen requirement of crops). The application was made at least a fortnight before sowing/planting operations. The analysis of soils collected before land application of spentwash and after harvest of crops revealed that there was no adverse effect of applied spentwash on soil characteristics. A slight build up in soluble salts was observed but, however all the soils recorded EC of less than 2.0 dSm-1. An increase in soil organic carbon (SOC) and available nitrogen (N) by about 10 to 30 % was observed in the spentwash applied soils. The presence of good amount of biodegradable organics in the treated spentwash (BOD of 6550 mg/l) contributed for increase in SOC and N. A substantial build up in available potassium (K) status (50 to 200%) was observed due to spentwash application. This was attributed to the high K content in spentwash (6950 mg/l). The growth of crops in the spentwash applied fields was higher and farmers could get nearly 10 to 20 per cent higher yields, especially in sugarcane and corn. The analysis of ground water samples showed that the quality of water was not affected due to land application of treated spentwash. Apart from realizing higher crop yields, the farmers were able to save money on N and K fertilisers as the applied spentwash met the crop requirement. Hence, it could be concluded that the bio-methanated distillery spentwash can be gainfully utilized in crop production without polluting the environment.

Keywords: bio-methanation, pollutant, potassium status, soil organic carbon

Procedia PDF Downloads 392