Average Flux Values Research Articles

Greenhouse gas emissions and crop-specific emission factors of eight upland crops based on a six-year field experiment in the North China Plain

Nitrous oxide is a significant greenhouse gas (GHG) contributor in crop production, yet detailed documentation, including crop yields and specific emission factors (EFd of N2O), are lacking for the North China Plain. A six-year (2016–2022) diversified crop rotation experiment in this region examined GHG emissions from eight crops (sweet potato, peanut, soybean, spring maize, sweet sorghum, ryegrass, summer maize, and winter wheat) and fallow seasons. The results revealed that summer maize had the highest cumulative soil N2O emissions (5.07 kg N ha−1), with an average flux value of 225.3 μg N2O-N m−2 h−1 during the growing season. Summer maize emitted 16–75 % more N2O than spring crops and winter wheat and 85–86 % more than ryegrass (cover crop) and the winter fallow season. All eight crops acted as weak net CH4 sinks. Annual average CO2-equivalents of N2O and CH4 emissions reflected N2O emissions from all crops and fallow seasons. In addition, GHG footprint metrics (GFa, per unit area; GFy, per kg equivalent yield; GFb, per kg biomass; GFe, per unit economic benefit) based on life cycle assessment thinking showed that intensive cereal crops (winter wheat and summer maize) had the highest GHG footprints, while sweet potato had the lowest due to its greater biomass and lower N input. Other crops had 19–90 % lower GHG footprints than wheat and maize. Furthermore, we also quantified specific-crop EFd of N2O, with ryegrass having the lowest EFd (0.48 ± 0.02 %), followed by winter wheat (0.81 ± 0.43 %), and other crops ranging from 1.00 ± 0.13 % to 2.36 ± 0.85 %. This study provides important emissions data for different crops and winter fallow periods, enhancing our understanding of GHG footprints and emission factors, which are essential for the advancement of sustainable agriculture practices.

Carbon Stock and CO2 Fluxes in Various Land Covers in Karang Gading and Langkat Timur Laut Wildlife Reserve, North Sumatra, Indonesia

Mangrove forests play an important role in coastal areas from an ecological perspective, being able to store large amounts of carbon through sequestration and inhibiting climate change processes by absorbing CO2 in the atmosphere. In recent years, there have been changes in the land cover of converted and degraded mangrove forests which have resulted in the release of carbon and an imbalance in soil structure, which in turn cause a flux of CO2 into the atmosphere. This research was conducted at the Karang Gading and Langkat Timur Laut Wildlife Reserve (KGLTLWR) in North Sumatra, Indonesia. The study focused on six different land covers, namely natural forests, restoration, mixed agriculture, paddy fields, oil palm plantation, and ponds. This study aimed to measure the total carbon stock of mangrove forests that have been converted to other land covers and estimate the level of CO2 flux in the area. A total of three transects and six plots for each land cover were used in this study; for tree biomass, a non-destructive method was used by recording every DBH > 5 cm, and for soil carbon, drilling was carried out, which was divided into five depths in each plot. CO2 flux was measured using an Eosense Eosgp CO2 sensor with the static closed chamber method. The highest carbon stock was found at 308.09 Mg ha−1 in natural forest, while the lowest 3.22 Mg ha−1 was found in mixed agriculture. The highest soil carbon was found at 423.59 MgC ha−1 in natural forest, while the lowest 50.44 MgC ha−1 was found in mixed agriculture dry land. The highest average CO2 flux value of 1362.24 mgCO2 m2 h−1 was found in mangrove restoration and the lowest in ponds was 123.03 mgCO2 m2 h−1. Overall, the research results inform how much carbon stock is lost when converted to other land covers so that it can be used as a reference for policy makers to provide future management of mangrove forests and develop mitigation measurements to reduce carbon emissions.

Investigating the impact of modeling assumptions and closure models on the steady-state prediction of solar-driven methane steam reforming in a porous reactor

In this work, the effect of different modeling assumptions and closure models — frequently considered in the literature of solar thermochemical reactors and closely-related areas — is investigated. The application of different modeling assumptions and closure models may strongly affect the results accuracy and compromise a meaningful comparison across literature works. The following is herein investigated: (i) the role of upstream and downstream fluid regions to the two-phase reactor region; (ii) relevance of species and gas-phase thermal diffusion mechanisms; (iii) reaction heat accounted for in gas- or solid-phase energy balance equations; (iv) local thermal equilibrium (LTE) vs. local thermal non-equilibrium (LTNE) models; (v) model dimension (one-dimensional vs. two-dimensional axisymmetric models); (vi) local volumetric convection heat transfer correlations; and (vii) effective solid thermal conductivity correlations. The relevance of this work extends well beyond the current application (methane steam reforming in a volumetric solar reactor), since similar models and assumptions have also been widely applied for predicting the performance of volumetric solar absorbers and dry reforming solar reactors. The results show that an upstream fluid region should be considered while applying inlet first-type boundary conditions and diffusion transport in the corresponding governing equations to ensure full-conservation and simultaneously to account for developing profiles upstream the reactor inlet section. For the operating conditions considered, species diffusion and gas-phase heat conduction are particularly relevant at the reactor centerline but with a negligible integral effect. A significant difference in the reactor performance is observed while accounting for the reaction heat from surface reactions in the solid- or gas-phase energy balances — for the lowest inlet gas velocity herein considered, the thermochemical efficiency (methane conversion) is approximately equal to 70.8% (76.3%) and 77.3% (84.7%) assigning the reaction heat to the gas- and solid-phase energy balances, respectively. LTE model results are strikingly different from the results obtained with the LTNE model considering the reaction heat accounted for in the gas-phase energy balance but not significantly different from the results computed with the LTNE model with the reaction heat assigned to the solid-phase energy balance. One-dimensional reactor modeling provided with an average concentrated solar heat flux value results in a similar average performance as that given by a two-dimensional model but fails to predict the high temperatures observed at reactor centerline — for the lowest inlet gas velocity, the difference between the maximum solid temperatures predicted by one- and two-dimensional models is about 340K.

Ultrafiltration with in-line coagulation (FeCl3) to enhance arsenic removal and improve drinking water quality: From bench to pilot-scale

There is a growing interest in advanced technologies to guarantee drinking water safety in scenarios of increasingly polluted water sources. Based on that, this paper discusses the use of ultrafiltration membranes aided by in-line coagulation with FeCl3 (0.086 – 0.172 mg/L) to improve the resilience of drinking water treatment plants. The process was considered after the settling units and was first studied on a bench scale, later validated in a pilot plant that operated continuously for approximately 31 days. In experiments without an in-line dose of FeCl3, the average flux values corresponded to 189.9 ± 11.8 L/m2h, compared with 193.4 ± 5.3 L/m2h for experiments when the coagulant was considered. The flux decay was lower in experiments with an in-line dose of FeCl3 (J/J0 > 0.95) and analysis of particle sizes revealed that the average diameter increased from 24.1 to 29.2 µm after the coagulant was added. Consequences related to a greater particle size were a fouling layer more porous permeable, and with a lower hydraulic resistance. The additional coagulant dosage also acts on the residual natural organic matter, monitored by excitation-emission matrices. Furthermore, the results show that the concentrate recirculation to the beginning of the water treatment plant did not affect its overall performance. In fact, concentrate recycling would increase the recovery rate of ultrafiltration membranes and reduce losses during water treatment. Similar observations were obtained in pilot-scale operations, that validated the in-line dose on a more representative system that is closer to the full-scale treatment process.

CH4 and N2O fluxes during paddy rice crop development, post-harvest, and fallow

Paddy fields are major sources of greenhouse gases, mainly methane (CH4) and nitrous oxide (N2O). Defining the sampling times for determining the average diurnal emission rates is an important step in optimizing field measurement, avoiding the influence of possible peaks. With this purpose, diurnal gas measurements (CH4 and N2O) were taken using the static chamber method during five 24 h-periods (campaigns), every 2 h, at three rice crop development stages (R2, C1 campaign; R5, C2 campaign, and R8, C3 campaign), and in post-harvest (PH, C4 campaign) and in fallow (FP, C5 campaign) periods. The CH4 fluxes remained close to the average flux both at C1 (9.4 ± 1.0 mg CH4 m-2 h-1) and C2 (10.2 ± 1.4 mg CH4 m-2 h-1), allowing the gas sampling at any time of the day, except at 5:00 p.m. when a peak was observed at C1. As the CH4 fluxes for C3, C4, and C5 were close to zero, no average value was identified. The average N2O fluxes were low at C1 (1.0 ± 5.7 μg N2O m-2 h-1) and at C4 (6.7 ± 2.6 μg N2O m-2 h-1), increasing at C2 (26.9 ± 9.3 μg N2O m-2 h-1) and C3 (21.2 ± 7.2 μg N2O m-2 h-1) and reaching higher values during the C5 campaign (73.7 ± 33.3 μg N2O m-2 h-1). In general, considering the average flux values recorded in this study, the most appropriate times for sampling N2O during the C1, C2, C3, and C4 campaigns would be from 9 p.m. to 1 a.m. and also around 11:00 a.m. Average N2O flows in fallow would be more likely around 11:00 p.m. and 11 a.m.

Spatio-Temporal Variations, Fugacity Fractions and Air-Soil Exchanges of PCBs in Industrial, Urban and Semi-Rural Sites

This study investigated the spatiotemporal variations in the occurrence of polychlorinated biphenyl (PCB) congeners both in soil and ambient air. Soil and air samples were taken simultaneously for three seasons (spring, summer, and autumn) from industrial, urban, and semi-rural areas in Bursa, Turkey. Light and medium PCB homologous groups were dominant in all samples. Total PCB (∑25 PCBs) concentrations in the air were 0.12 ± 0.13, 0.06 ± 0.07, and 0.08 ± 0.11 ng/m3 and in soil were 4.01.±2.38, 5.44 ± 3.14, and 3.66 ± 1.56 ng/g DM for summer, spring, and winter, respectively. Moreover, the samples were taken from different sites to determine the spatial fluctuations. The average ∑25 PCBs in the air were 0.22 ± 0.06, 0.03 ± 0.01, and 0.03 ± 0.02 ng/m3 and in soil were 7.08 ± 1.84, 2.98 ± 0.52, and 3.06 ± 0.70 ng/g DM for industrial, urban and semi-rural sites, respectively. Maximum air and soil PCB concentrations were determined in the industrial region. The spatiotemporal changes in the fugacity fractions and net fluxes were also examined. The direction of the PCB movement was assessed and the results indicated that soil was a diffusive source for PCBs. The calculated fugacity fractions (ff) were above 0.7 while average flux values were calculated as 0.65 ± 0.33 ng/m2-d, 0.21 ± 0.19 ng/m2-d, and 0.26 ± 0.27 ng/m2-day for industrial, urban and semi-rural regions, respectively.

Improvement of uniformity of irradiance on truncated compound parabolic concentrator by introducing the homogenizer ratio

A compound parabolic concentrator (CPC) with a flat absorber is widely used in low-concentrating photovoltaic thermal (CPVT) systems. CPC certainly develops non-uniform heat flux distribution over the absorber surface which is significantly reduced by the integration of homogenizer referred as Elongated CPC (ECPC). The objective of the present work is to analyse the effect of homogenizer ratios, truncation ratios and concentration ratios on the heat flux distribution characteristics of a CPC collector. In this paper, a ray tracing simulation is carried out to obtain the heat flux distribution profiles and the same is incorporated within CFD software to obtain the temperature distribution profiles. As a result, it is observed that the optimum truncation ratio would be 0.7 at which uniformity in flux distribution is improved by 3%, with just 2% reduction of average heat flux value. Furthermore, with optimized homogenizer ratio of −0.35 at concentration ratio of 3, 64% improvement in uniformity of flux distribution has been noticed. From the study, it has been concluded that for different concentration ratios of 1.5, 2, 3, 4, 5, 6, 7 and 8, the optimum homogenizer ratio is observed to be −0.9, −0.55, −0.35, −0.25, −0.2, −0.15, −0.15 and −0.05 respectively.

Pressure And Spacer Effect On The Performance Of Immersed Microfiltration Membrane

The water treatment applied in PDAM Surabaya City to treat Kali Surabaya still uses a conventional process where the treatment process will get even harder with decreasing quality of raw water. Immersed microfiltration membrane is a reliable technology in water treatment compared to conventional technology. Nevertheless, the performance of the membrane decreases due to deposits that occur on the membrane surface and lead to fouling. This study aims to examine the effect of pressure and spacers on the performance of microfiltration ceramic membrane measured based on quality and quantity parameters. The research parameters used were turbidity, TSS, organic matter, total coliform, E. Coli and the number of microplastic while the quantity parameters included flux, amount of water production and the duration of membrane operation before fouling. This study tested immersed flat-sheet microfiltration ceramic membranes in sedimentation unit of PDAM Ngagel III Surabaya City. Membrane operation used cross-flow with variable pressure (0.6 bar, 0.7 bar, 0.9 bar) and spacer slopes (75°, 90°, 105° and without spacers). Based on the results of the study, it was found that the effect of optimal pressure occurred at 0.7 bar with the efficiency of eliminating turbidity, TSS, organic matter, microplastic, total coliform, and E. Coli parameters respectively, 94.66%, 96.88%, 24.29%, 62.27%, 100% and 100%. The average flux value at pressure 0.7 bar is 64,33 L/m2.hour with operating duration of 55 hours and permeate production volume 530.70 L. The optimal spacer effect was achieved at slope of 90° with the efficiency of eliminating turbidity, TSS, organic matter, microplastic, total coliform and E. Coli parameters respectively 95.12%, 64.58%, 28.75%, 84.74%, 99.99% and 100%. The average flux value was 66,78 L/m2.hour with an operating duration of 90 hours and permeate production volume 901.55 L.

Effects of swirl injection on the combustion of a novel composite hybrid rocket fuel grain

The combustion characteristics obtained from the coupling effect between swirl injection and a novel composite hybrid rocket fuel grain were investigated. The novel composite fuel grain was composed of a three-dimensional printed acrylonitrile-butadiene-styrene (ABS) helical substrate with an embedded paraffin-based fuel. Two swirl flow injectors with opposite injection directions were designed: one with the same injection direction as the swirling direction induced by the ABS helical substrate and the other having the opposite direction. Axial injection trials were also performed as a baseline for comparison. Firing tests were carried out using a lab-scale hybrid rocket engine with oxygen as the oxidizer at average mass flux values in the range of 2.1–4.5 g/(s·cm2). When combined with either swirl flow injector, the novel composite fuel grain exhibited excellent combustion properties. Compared with the axial flow injector, both swirl injectors greatly improved the regression rate of the novel composite fuel grain, by 82.4% and 50.6% respectively, at an oxygen mass flux of approximately 4.25 g/(s·cm2). Three-dimensional imaging of the inner surface of the novel composite fuel grain and cold flow numerical simulations were employed to assess the mechanism by which the regression rate was increased. The results of these analyses elucidated the effects of different injection methods on the oxidizer-to-fuel ratio distribution during combustion of the novel composite fuel grain.

Диагностика интенсивностей излучения и электронной концентрации в полярных сияниях по данным эмпирических моделей электронных высыпаний.

We have studied the influence of the precipitating electron spectrum shape on the integral intensity of emissions λ391.4 nm 1NG N⁺₂, λ670.4 mn 1PG N₂, λ337.1 nm 2PG N₂, λ320.0 nm VK N₂, λ127.3 nm LBH N₂, atomic oxygen emissions λ557.7 and λ630.0 nm, total electron content in the vertical column of aurora. The integral characteristics of the emission intensity and the total electron content are shown to weakly depend on the energy spectrum shape and to be determined mainly by average energy values Eev and energy flux value Fᴇ of precipitating electrons. An algorithm is proposed for diagnosing the planetary distribution of emission intensities and total electron content in auroras based on data from empirical electron precipitation models, without making a priori assumptions about the shape of the energy spectrum of precipitating electrons.

Diagnostics of emission intensities and electron density in auroras based on empirical precipitation models

We have studied the influence of the precipitating electron spectrum shape on the integral intensity of emissions λ391.4 nm 1NG N⁺₂, λ670.4 mn 1PG N₂, λ337.1 nm 2PG N₂, λ320.0 nm VK N₂, λ127.3 nm LBH N₂, atomic oxygen emissions λ557.7 and λ630.0 nm, total electron content in the vertical column of aurora. The integral characteristics of the emission intensity and the total electron content are shown to weakly depend on the energy spectrum shape and to be determined mainly by average energy values Eev and energy flux value Fᴇ of precipitating electrons. An algorithm is proposed for diagnosing the planetary distribution of emission intensities and total electron content in auroras based on data from empirical electron precipitation models, without making a priori assumptions about the shape of the energy spectrum of precipitating electrons.

Photon detector response function methodology using MCNP and shift hybrid radiation transport code for wide-area contamination assay applications

Radiation transport modeling using the Monte Carlo N-Particle (MCNP) radiation transport code and Monte Carlo code, Shift, were employed to model detector responses for a variety of wide-area photon contamination scenarios. In this study, 2′′ × 2′′ and 3′′ × 3′′ cylindrical NaI(Tl) scintillation detector configurations at source detector-distances of 0.5 cm, 1 cm, 2.54 cm, 10 cm, and 30 cm were modeled. Media of soil, concrete, and steel were evaluated for contamination depths ranging from surface to a depth of an infinite thickness in each medium for photon energies ranging from 20 keV to 3 MeV, which correspond to the energies that current detectors can discern. Monoenergetic photon surface contamination detector responses for each of the media, source–detector distances, and detectors were estimated using MCNP v6.2. Shift was harnessed for improved variance reduction of particle transport in highly attenuating media to obtain average cell fluxes in the two MCNP NaI(Tl) scintillation detector configurations. Average cell flux values in Shift were coupled with detector responses from MCNP to convert average cell flux in a void to energy distribution of pulses in the NaI(Tl) scintillation detector crystal of interest. An optimized detector response function methodology was developed by coupling the MCNP radiation transport method with the Consistent Adjoint Driven Importance Sampling (CADIS) hybrid radiation transport method built into Shift to significantly decrease the runtime of thousands of MCNP pulse height simulations. The methodology may be utilized to quickly and accurately facilitate the assessment of a broad range of wide-area environmental contamination assay and decommissioning cleanup applications.

Hydraulic characterization of porous pipes

Abstract Increased anthropic activity in the environment leads to degradation and increased waste generation that includes tires, which can be used for the manufacture of porous pipes by extrusion for irrigation or aeration. There are no defined methodologies for the hydraulic characterization of porous pipes; in addition, their performance is questionable because the permeability of the wall in contact with water seems to decrease with time. Thus, this study aimed to perform the hydraulic characterization of porous pipes. Experiments were performed to assess the variation in permeability over time, the head loss, the friction factor, and the roughness. Statistical tests were performed to investigate possible significant differences between treatments. The results showed that the permeability varies over time and tends to decrease with each application of water. After a certain period, the permeability tends to become constant, and a stable flux can be determined, being the lowest average permeability and flux values found 0.591 × 10−15 m² 0.109 m³·m−2·s−1. There is variability in the permeability between pipe samples from the same batch as well as variability within the same sample, as indicated by the fact that some samples are similar to each other while others differ when performing a pairwise multiple comparison.

Production enhancement of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in Halogeometricum borinquense, characterization of the bioplastic and desalination of the bioreactor effluent

Polyhydroxyalkanoates (PHAs) are a replacement of conventional single-use plastics. Bioprocess conditions of the extreme halophilic archaeon Halogeometricum borinquense strain RM-G1 were selected resulting in the synthesis of 66.80 ± 1.69 % PHA (of cell dry mass) in 72 h using glycerol and tryptone as carbon and nitrogen sources respectively, yielding volumetric productivity of 0.206 ± 0.006 gL−1 h−1 in a repeated batch process in a small-scale bioreactor where 20 % of the production medium was used as the inoculum for the subsequent batch. The purified PHA was characterized as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with 10.21 mol% 3-hydroxyvalerate content possessing glass transition temperature -12.6 °C, degradation temperature 285 °C, number average molecular weight 156,899 Da, weight average molecular weight 288,723 Da, polydispersity index 1.8 and melting temperatures 139.1 °C and 152.5 °C. Maximum (21.7 ± 0.6 L m-2 h−1) and average (17.2 ± 0.6 L m-2 h−1) flux values were their respective highest and crystallization time was its least (3.0 ± 0.16 h) when ΔT was 90 °C and polytetrafluoroethylene membrane was applied for desalination of the bioreactor effluent by Direct Contact Membrane Distillation. While using polyvinylidene fluoride membrane, maximum 25.5 ± 0.5 L m-2 h−1 and average 18.6 ± 0.2 L m-2 h−1 fluxes were obtained and crystallization time decreased (3.25 ± 0.16 h) even when ΔT was lowered by 20 °C.

Thiol-Affinity Immobilization of Casein-Coated Silver Nanoparticles on Polymeric Membranes for Biofouling Control.

Silver nanoparticles (AgNPs) have been widely studied for the control of biofouling on polymeric membranes due to their antimicrobial properties. However, nanoparticle leaching has posed a significant impediment against their widespread use. In this study, a one-step method of chemically embedding AgNPs on cellulose acetate (CA) membranes via their affinity to thiol group chemistry was investigated. The operational efficiency of the membranes was then determined via filtration and biofouling experiments. During filtration study, the average flux values of pure CA membranes was determined to be 11 ± 2 L/(m2·hr) (LMH), while membranes embedded with AgNPs showed significant increases in flux to 18 ± 2 LMH and 25 ± 9 LMH, with increasing amounts of AgNPs added, which is likely due to the NPs acting as pore formers. Leaching studies, performed both in dead-end and crossflow filtration, showed approximately 0.16 mg/L leaching of AgNPs after the first day of filtration, but afterwards the remaining chemically-attached AgNPs did not leach. Over 97% of AgNPs remained on the membranes after seven days of crossflow leaching filtration studies. Serratia marcescens were then used as target microorganisms in biofouling studies. It was observed that membranes embedded with AgNPs effectively suppressed the growth of Serratia marcescens, and specifically, membranes with AgNPs displayed a decrease in microbial growth by 59% and 99% as the amount of AgNP increased.

Comparison of Van Allen Probes Energetic Electron Data With Corresponding GOES‐15 Measurements: 2012–2018

AbstractElectron fluxes (especially at energies E > 0.8 and 2 MeV) have been measured for many years by sensors on board the Geostationary Operational Environmental Satellite (GOES). These long‐term data (nominally at L ~ 6.6) have become a mainstay for monitoring the Earth's radiation environment. We have carried out a study directly comparing the comprehensive radiation belt particle measurements from the National Aeronautics and Space Administration dual‐spacecraft Van Allen Probes (Radiation Belt Storm Probes) sensor systems with selected GOES operational data. The Van Allen Probes have measured the properties of radiation belt electrons virtually continuously from September 2012 to 2018. We make statistical comparisons of Van Allen Probes electron data near L = 6 with concurrent daily averages of equivalent GOES‐15 flux values. We also compare Van Allen Probes data at various other L values and at a much broader range of particle energies with the more limited baseline GOES‐15 values. These comparisons inform us about the relative calibrations between the scientific and operational systems and also allow us to assess how well GOES data correlate with radiation belt behavior well away from the geostationary orbit location. We find that GOES daily average flux values can be a factor of 100 (or more) below the corresponding Van Allen Probes daily averaged fluxes at L = 6.0. This is due to the fact that GOES at stationary orbit often has excursions over large ranges of L space during a given day and strong radial gradients exist in this region of the magnetosphere. These results indicate that it is crucial to augment geosynchronous GOES observations with observations in the core of the outer belt (L ≲5.0).

Treatment of batik wastewater using plant derived surfactant-enhanced ultrafiltration membrane

Saponin extract from pericarps of Sapindus rarak DC is utilized to replace synthetic surfactant in the surfactant-enhanced ultrafiltration process. The process conducts to treat real batik wastewater. The extraction by maceration methods was performed in the various ratio of solute to solvent. The extract with proper calculation is used in the wastewater treatment process in various CMC concentration. The highest yield is obtained at solute to solvent ratio of 1:40 (w/v). The flux value of solution without saponin is higher than the one with saponin addition.The flux value is decreased by the increase of saponin concentration on the feed solution. Thelowest average flux value of 31.35 L/m2.h was obtained from the feed solution with saponin concentration of 2 times CMC. Both processes with and without the addition of saponin exhibit permeate flux declined over time. This is due to the interaction of saponin molecule with the pollutant where the pollutant is covered by saponin molecules. The membrane performance shows that saponin is successfully worked to solubilize or bounded the heavy metal molecule, dyes molecules, and other pollutants on its micellar structure. This is proved by the decrease of Cr and COD concentration after the ultrafiltration process enhanced with saponin. Saponin at the concentration of 2 times CMC giving the best result with lowest Cr and COD concentration of 18.3 ppm and 108.4 ppm, respectively, and highest rejection of Cr and COD of 95.88% and 96.91% respectively.

A Numerical Study of the Effect of Aspect Ratio on Heat Transfer in an Annular Flow Through a 270-Degree Curved Pipe.

In the present paper, a three dimensional annular developing incompressible laminar flow through 270- degree curved pipe is numerically simulated. The dimensionless governing equations of continuity, momentums and energy are driven in toroidal coordinates. The governing equations are discretized by projection algorithm using forward difference in time and central difference in space. A three-dimensional computer code together with a grid generation program are developed in toroidal coordinates by which the present results were obtained. There is a non-uniform heat source q˝=BeAθ in the solid core and the outer wall is assumed to be adiabatic. Considering the effect of Reynolds number on thermo-hydraulic properties such as formation of secondary flow and axial velocity, it is possible to increase heat transfer using a non-uniform heat flux instead of the uniform one. The numerical results indicated that the average Nusselt number is increased by non- uniform heat flux compared with the uniform one assuming that both have the same average flux values. Also, the results indicate heat transfer increases as the aspect ratio is reduced.

The effect of horn-manure preparation on enzymes activity and nutrient contents in soil as well as great pumpkin yield

Abstract This investigation was inspired by an increasing global issue on how to improve soil quality while using alternative preparations instead of synthetic fertilizers. The main aim of a three-year study was to investigate the influence of horn-manure preparation on enzyme activity and nutrient content in soil and pumpkin yield. The results showed that significantly higher amounts of P (respectively 106 and 79 mg kg−1 CAL), K (149 and 106 mg kg−1 CAL), nitrogen (5.41 and 3.21 mg kg−1), ammoniacal nitrogen (9.38 and 3.45 mg kg−1) and mineral nitrogen (7.97 and 5.67 mg kg−1) were measured in the plots where the horn-manure preparation was used. A higher activity of the soil enzymes (urease activity was 1.93 times higher and the saccharase activity was 1.05 times higher) were identified with horn-manure. The average soil CO2 flux (Fc) value, when using horn-manure preparation (from 56 till 70 day), was significantly higher by 5.32% in the middle of the growing season. The yield of pumpkin was significantly increased by 18% with horn manure treatments. Significant positive correlations were identified between pumpkin yield and urease activity, and saccharase activity, as well as soil P and K.

Retraction: Estimation of sediment accumulation rates using naturally occuring 210Pb models and heavy metal measurements in Gülbahçe Hydrothermal Vent Zone

In this study, sediment chronology was determined by using Lead-210 (210Pb) dating models in Gulbahce Bay. Sediment cores were obtained via a gravity core sampler from hydrothermal area and also from reference point and surficial distribution of Polonium-210 (210Po) was investigated in the study area. The average surficial 210Po concentration was relatively higher in hydrothermal area than the reference point. Sedimentation rates in Core reference point (RN) displayed an increase till the 1940’s and a decrease afterwards, sedimentation rates in any core from hydrothermal area did not exhibit regular continuous increase or decrease. The 210Pb fluxes measured from core inventories are close to each other but they are a bit higher than the average mediterranean and mean atmospheric 210Pb flux values. This situation indicates that there are outer contribution to the study area apart from atmospheric precipitation of 210Pb concentration. Average enrichment factors indicating that the sediments have not been co...