Concentration Of Urea Solution Research Articles

Influence of carbonate-inducing bacteria on desulfurization effect of medium and high sulfur coal gangue under spraying and preparation of desulfurized coal gangue mortar

Medium and high sulfur coal gangue (MHSCG) presents challenges for safe application on civil engineering building materials due to the high content of unstable pyrite, of which the acidic oxidation products are against alkali cementitious materials. For better utilization of MHSCG, in this research, the carbonate-inducing bacterium Sporosarcina Pasteurii with its nutrient (urea) and mineralization source (calcium) was firstly explored in MHSCG desulfurization leaching tests, revealing the mechanism of desulfurization. On this basis, the desulfurizing modification on MHSCG sand by the bacteria under different factors of OD600, urea and calcium was conducted. Moreover, the gangue sand was used to prepare the desulfurized coal gangue mortar (DCGM) and the relevant mechanical properties and influence mechanisms were discussed. The results of total sulfur and XRD analysis show that Sporosarcina Pasteurii can accelerate the desulfurization in the 7-days-spraying modification. When the optimum dosages of OD600 (0.84) and urea solution concentration (1.41 mol/L) are adopted, the total sulfur can be reduced by 33.66∼36.32 %. The total sulfur has been further reduced by 7.69 % compared with group without calcium as calcium concentration is 1.56 mol/L. The introduction of calcium can enhance the mechanical properties of MHSCG and DCGM although the desulfurization treatment has a negative impact on them. The crushing index of MHSCG sand at most decreases 10.44 % from it without calcium. When OD600 is about 0.90, urea concentration is about 1.50 mol/L and calcium concentration is about 1.49 mol/L, the 28-d compressive strength of DCGM increases to 32.01 MPa, 76.85 % higher than group without calcium, and 23.54 % higher than raw-material preparing mortar.

Effects of urea solution concentration on soil hydraulic properties and water infiltration capacity

Elucidating the effect of fertigation on soil hydraulic parameters and water-solute transportation is fundamental to the design of farmland irrigation systems and their sustainable utilization. Few studies have focused on soil hydraulic parameters or water infiltration characteristics or how they are influenced by urea solution concentration. In this study, the clay loam and sandy loam in Yangling District of Shaanxi Province, China, were used as test soil, and experiments involving seven urea solution concentrations (0.2, 0.4, 0.6, 0.8, 1, 3, and 5 g/L) and a control treatment (0 g/L) were conducted to explore the influence of the various urea solution concentrations on soil hydraulic parameters and water infiltration characteristics. The results indicated that the cumulative infiltration and wetting front migration depth increased with urea solution concentration, as accurately estimated using the Kostiakov model and a power function, respectively. In addition, the coefficients of the Kostiakov model and the power function increased with urea solution concentration. Treatment with multiple concentrations of urea solution resulted in an increase in the volume of macro pores in the soil but a reduction in the volume of mesopores and micro pores in the soil, leading to increases in the saturated water content, saturated hydraulic conductivity, soil water diffusivity, and infiltration capacity and a reduction in the water-holding capacity of the soil. The effect of urea solute potential on the inhibition of soil water movement is small, and this inhibitory effect is far weaker than the improvement effect of the urea solution on soil structure, and hence enhance the soil water infiltration capacity. Our results increase the understanding of soil hydrological mechanisms and may be usefully applied for improving the management of fertigation.

Determination of the Diffusion Coefficient of Urea Solution Using Double Exposure Digital Holographic Interferometry (DEDHI) to Study Plant Growth-=SUP=-*-=/SUP=-

In this paper, we have used the double exposure digital holographic interferometry (DEDHI) technique to determine the diffusion coefficient of urea in pure distilled water at 27oC (room temperature) and it is used further to predict urea movement in soil by considering the concentration of urea solution and diffusion coefficient to study early plant growth. We have recorded several consecutive digital holograms of diffusing solutions of urea and pure distilled water at different times instantaneously on the CCD chip and processed them with H-Digital numerical reconstruction software on the computer. It is observed that as the concentration of urea solution increases from 0 to 4 M, diffusion coefficient 'D' of urea slightly increases from 12.2 to 13.8 × 10^-6 cm^2/s, which considerably affects the growth of the plants.

High stability potentiometric urea biosensor based on enzyme attached nanoparticles

Highly stable new urea biosensor was prepared by using poly(2-hydroxyethyl methacrylate-glycidyl methacrylate) nanoparticles, which was used as a nano-carrier for urease enzyme. The urea biosensor was prepared by an ammonium selective electrode along with the urease immobilized nanoparticles. Synthesized nanoparticles were characterized by SEM and attachment of the enzyme onto the nanoparticles was evaluated by EDX analysis. Potentiometric response of the biosensor was examined as a function of the different concentrations of urea solution, and linear concentration range of urea was demonstrated in the range of 0.01 mM-500 mM. The detection limit was also investigated and measured as 0.77 µM. Response time of the biosensor was also determined as 30 s. Repeatability of the urea biosensor system was found to be very high, and it was demonstrated that response of the urea sensor was protected by 95.7% at the end of the 170th reuse. This biosensor system protected 83% of its initial activity at the end of the 90 day storage. Additionally, interference profile of the urea biosensor was tested against the common interferents such as ascorbic acid (AA), uric acid (UR), glucose (GL) and sodium ions (Na+), and the response of these interfering agents was found to be as negligible. Also, applicability of the synthesized urea sensor for detection of urea from artificial human serum was demonstrated.

Dielectric properties of soil mixed with urea fertilizer over 20 Hz to 2 MHz frequency range

The dielectric properties of sandy soil for various moisture contents of distilled water and Urea-fluid solutions in soil are estimated in the lower frequency range from 20 Hz to 2 MHz using precision LCR meter. The spectra of complex permittivity e*(ω), loss tangent tan δ(ω), electrical conductivity σ*(ω), and complex impedance Z*(ω) plane plots of these soil-fluid system have been investigated for various moisture contents of different concentrations of Urea solution in the soil samples. The dielectric constant and dielectric loss of the soil increase with increase in moisture content of different concentrations of Urea solution in the soil. The dielectric constant and dielectric loss of the soil increases significantly with the decrease in frequency over the given frequency range. The complex impedance plane (Zʹ versus Zʺ) plot separates electrode polarization and bulk material phenomena, which can also be observed in the dielectric loss tangent peaks.

Urea as a single denaturing agent in deproteinisation of natural rubber latex

This paper describes the utilisation of urea as a single chemical agent to obtain deproteinised high ammoniated natural rubber latex (HA-NRL). The role of urea in HA-NRL deproteinisation was further investigated by employing two different concentrations of urea solution which are low (0.01–0.05%) and high (1.0–5.0%) concentrations. The study assessed the potential usage of urea as a single denaturing agent in the presence of neither stabilising agent nor additives during the deproteinisation process. The effect of different urea concentrations on properties of deproteinised NRL was further scrutinised by using sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE), nitrogen content analysis, extractable protein (EP) content, Zeta potential, attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and physical strength. The presence of residual urea is pertinent as the concentration of urea increases while contributing to the increase of total nitrogen content in the resultant film. Leaching the film with hot water is sufficient to remove the residual urea as supported by an ATR-FTIR analysis. Initial exploratory data analysis of low and high urea concentrations on the effect of nitrogen content, EP, surface charge properties of latex and green strength of the deproteinised NRL were evaluated and their relation to each factor was further discussed. Based on the initial findings, urea was observed to be less effective as a single denaturant. Nonetheless, the properties of the deproteinised HA-NRL treated with urea were revealed to be markedly influenced by the urea concentration.

The design of detection system for concentration of urea solution in vehicle and its application in SCR

The design of detection system for concentration of urea solution in vehicle and its application in SCR

Effective NiMn Nanoparticles-Functionalized Carbon Felt as an Effective Anode for Direct Urea Fuel Cells.

The internal resistances of fuel cells strongly affect the generated power. Basically, in the fuel cell, the anode can be prepared by deposition of a film from the functional electrocatalyst on a proper gas diffusion layer. Accordingly, an interfacial resistance for the electron transport is created between the two layers. Electrocatalyst-functionalized gas diffusion layer (GDL) can distinctly reduce the interfacial resistance between the catalyst layer and the GDL. In this study, NiMn nanoparticles-decorated carbon felt is introduced as functionalized GDL to be exploited as a ready-made anode in a direct urea fuel cell. The proposed treated GDL was prepared by calcination of nickel acetate/manganese acetate-loaded carbon felt under an argon atmosphere at 850 °C. The physiochemical characterizations confirmed complete reduction for the utilized precursors and deposition of pristine NiMn nanoparticles on the carbon felt fiber. In passive direct urea fuel cells, investigation the performance of the functionalized GDLs indicated that the composition of the metal nanoparticles has to be optimized as the GDL obtained from 40 wt % manganese acetate reveals the maximum generated power density; 36 mW/m2 at room temperature and 0.5 M urea solution. Moreover, the electrochemical measurements proved that low urea solution concentration is preferred as utilizing 0.5 M solution resulted into generating higher power compared to 1.0 and 2.0 M solution. Overall, this study opens a new avenue toward functionalization of the GDL as a novel strategy to overcome the interfacial resistance between the electrocatalyst and the GDL.

Preparation of TiO<SUB align="right">2 film on Ag and Al electrode for electrochemical bio-sensing application

In this present, work, titanium dioxide (TiO2) deposited on Ag and Al electrodes were fabricated by sol-gel chemical wet and dry (CWD) method to detect urea. The formation of the polycrystalline TiO2 deposited on Ag and Al substrates were confirmed by X-ray diffraction (XRD) analysis. The XRD analyses of both the samples clearly indicated that some percentage of Ag and Al diffuses into the TiO2 matrix at its interface region. The nature of I-V characteristics showed by the TiO2 on Ag and Al wire electrodes are found to be Ohmic and is perfect to be used for electrochemical sensor or bio-sensor at very low potential value. The performance and response to various concentrations of urea solution and pH level were experimentally studied by using TiO2 coated on Ag and Al as working electrodes with respect to Ag as reference electrode.

Neutralizing formaldehyde in chicken cadaver with urea and urea fertilizer solution.

This study demonstrated the potential of using urea and urea fertilizer to neutralize formaldehyde (Fd) in chicken cadavers. Initially, in vitro Fd neutralization with various concentrations of urea solution (US) and urea fertilizer solution (UFS) was conducted; subsequently, 18% US and 27% UFS were selected for infusing into the formalinized chickens. The measurement at 48 hr after infusion showed that both solutions could effectively lower Fd in chicken cadavers to below a permissible exposure limit without affecting cadaveric and histological quality. In addition, neutralizing power of 18% US was approximately 1.3 times that of 27% UFS. This is the first demonstration of neutralizing potential of US and UFS against Fd both in vitro and in vivo.

Optimization of Fluidised Bed Granulation Process Parameters for Urea Granule Manufacturing Using the Response Surface Method

Fluidised bed technology is commonly applied in the pharmaceutical, agricultural and food production technology. The aim of this work is to identify the optimum process parameters in order to gain the best hardness and density values for the urea granules from the fluidised bed granulation. The layout of the experiments are based on Central Composite Design of Response Surface Method. The analyzed data shown that the optimize value for each of these parameter are 0.10MPa, 32.11Hz, 50% w/w, 42.250C for spray pressure, fan speed, urea solution concentration and inlet air temperature with 1.71 kgf/granule hardness and 1.85 g/cm3 density were predicted. Experimentally, using the predicted optimize input parameter, the hardness and density observed were 0.20 kgf/granule and 1.30 g/cm3 respectively.

Study on the Swelling Behavior of Gamma Radiation Induced Acrylamide/Carboxymethyl Cellulose Blend Hydrogel in Urea Solution.

Swelling behaviors of crosslinked acrylamide (AAm)/carboxymethyl cellulose sodium salt (CMC) blend hydrogels synthesized using gammaradiation from Co-60 source in aqueous solutions of urea were investigated. The parameters like effect of radiation dose and concentration of CMC in AAm/CMC blend were studied on swelling properties. Swelling experiments were performed in various concentrations of urea solution and distilled water at room temperature. The swelling properties of hydrogels increased with increased concentration of CMC but it decreased with increased radiation dose. Hydrogels showed enormous swelling in aqueous solution of urea. The swelling properties of AAm/CMC hydrogel were lower in distilled water than that of in urea solution. The water absorption of AAm/CMC blend hydrogels increased from ~4,800 to ~9,000% for the concentration range of CMC from 0 to 7% for 48 hours standing in distilled water at 25 kGy radiation dose. It was also found that water absorption by AAm hydrogel with 7% CMC decreased from ~13,800 to ~8,500% for the radiation range from 15 to 35 kGy for 48 hours standing time in water. The equilibrium water content (EWC) of AAm/CMC blend hydrogel depended on radiation dose. EWC decreased from ~0.9935 to ~0.9896 with the variation of radiation dose from 15 to 35 kGy in 0.01M urea solution at 48 hours.
 Dhaka Univ. J. Sci. 64(2): 105-108, 2016 (July)

Fibrin self-assembly is adapted to oxidation

Fibrinogen is extremely susceptible to attack by reactive oxygen species (ROS). Having been suffered an oxidative modification, the fibrinogen molecules, now with altered spatial structure and function of fibrin network, affect hemostasis differently. However, the potential effects of the oxidative stress on the early stages of the fibrin self-assembly process remain unexplored. To clarify the damaging influence of ROS on the knob ‘A’: hole ‘a’ and the D:D interactions, the both are operating on the early stages of the fibrin polymerization, we have used a novel approach based on exploration of FXIIIa-mediated self-assembly of the cross-linked fibrin oligomers dissolved in the moderately concentrated urea solutions. The oligomers were composed of monomeric desA fibrin molecules created by cleaving the fibrinopeptides A off the fibrinogen molecules with a thrombin-like enzyme, reptilase. According to the UV-absorbance and fluorescence measurements data, the employed low ozone/fibrinogen ratios have induced only a slight fibrinogen oxidative modification that was accompanied by modest chemical transformations of the aromatic amino acid residues of the protein. Else, a slight consumption of the accessible tyrosine residues has been observed due to intermolecular dityrosine cross-links formation. The set of experimental data gathered with the aid of electrophoresis, elastic light scattering and analytical centrifugation has clearly witnessed that the oxidation can serve as an effective promoter for the observed enhanced self-assembly of the covalently cross-linked oligomers. At urea concentration of 1.20M, the pristine and oxidized fibrin oligomers were found to comprise a heterogeneous set of the double-stranded protofibrils that are cross-linked only by γ–γ dimers and the fibers consisting on average of four strands that are additionally linked by α polymers. The amounts of the oxidized protofibrils and the fibers accumulated in the system were higher than those of the non-oxidized counterparts. Moreover, the γ and α polypeptide chains of the oxidized molecules were more readily crosslinked by the FXIIIa. Upon increasing the urea solution concentration to 4.20M, the cross-linked double-stranded desA fibrin protofibrils have dissociated into the single-stranded fibrin oligomers, whereas the fibers dissociated into both the double-stranded desA fibrin oligomers, the structural integrity of the latter being maintained by means of the intermolecular α polymers, and the single-stranded fibrin oligomers cross-linked only by γ–γ dimers. The data we have obtained in this study indicate that the FXIIIa-mediated process of assembling the cross-linked protofibrils and the fibers constructed from the oxidized monomeric fibrin molecules was facilitated due to the strengthening of D:D interactions. The findings infer that the enhanced longitudinal D:D interactions become more essential in the assembly of soluble protofibrils when the interactions knobs ‘A’: holes ‘a’ are injured by oxidation. The new experimental findings presented here could be of help for elucidating the essential adaptive molecular mechanisms capable of mitigating the detrimental action of ROS in the oxidatively damaged fibrin self-assemblage processes.

Study of the Emission Characteristics of the SCR System on CI Engine Fuelled with Diesel-Ethanol Blends and an Optimised Urea Injection System

The objective of this work is to determine the maximum reduction of NOx emissions by varying the concentrations of urea solution with a reduction catalyst, and optimization of the urea injection by the evaporation of the solution, using the CFD-Fluent solver. An aqueous solution of urea was injected in the engine exhaust pipe for reducing NOx emissions, in a single cylinder light duty, stationary, four stroke, air cooled DI diesel engine, fuelled with neat diesel and diesel-ethanol blends (10%). The concentration of the urea solution was varied from 30 to 35% by weight with constant flow rates, and tested with a Titanium dioxide (TiO2) coated catalyst, fitted on the engine exhaust pipe, which controls the by products of ammonia and water vapour. The results indicated that a maximum of 70% NOx reduction was achieved when the engine was fuelled with diesel-ethanol blends at a constant flow rate of 0.75 lit/hr with an urea concentration of 35%, and also that 66% reduction of NOx was achieved, using the Titanium dioxide catalyst in the Selective Catalytic Reduction system with neat diesel. From the simulation results,it was seen that only at 75% and 100% load,the evaporation point of the urea solution was higher than that of the boiling point (423 K), due to complete vaporisation of water.

Hydrolysis of Urea for Ammonia-Based Wet Flue Gas Desulfurization

Nowadays, the ammonia-based wet flue gas desulfurization is gaining more popularity. In this study, the ammonia-based wet flue gas desulfurization obtained ammonia resource from urea hydrolysis instead of anhydrous ammonia and aqueous ammonia, which was beneficial for the development of circular economy. An electric-heating reactor was employed as the hydrolysis reactor instead of traditional ones using hot air or water vapor as the heat carrier. The effects of temperature, pressure, urea solution concentration, and time on urea hydrolysis were investigated, and the optimum hydrolysis condition was estimated to be 30 (wt, %) urea solution hydrolyzing for 4 h at 140 °C, 0.4 MPa. The desulfurization experiment was conducted in a bubbling reactor. The effects of SO2 concentration and liquid–gas ratio on desulfurization were investigated. The ammonia-based absorbent for desulfurization was prepared by the ammonia produced from the 30 (wt, %) urea solution hydrolyzing for 4 h at 140 °C, 0.4 MPa. The experiment...

Experimental Study on NO<sub>x</sub> Reduction in CI Engine Fuelled with Biodiesel (Cotton Seed Methyl Ester Blends) Using Selective Catalytic Reduction (SCR) System with Anova Analysis

An experimental investigation was conducted to analyse the performance and exhaust emissions of Kirloskar AV-I Compression ignited air cooled engine fuelled with diesel and cotton seed oil blends (80% of diesel and 20% of cotton seed biodiesel).Experiments were conducted at various concentration of urea solutions ranging from 30 to 35% at a constant flow rate of 0.75 litres per hour. The results indicated that urea injection with titanium dioxide as selective catalyst in the exhaust pipe caused a 47.9% of NOx reduction for diesel at full load condition and at a constant flow rate of 0.75lit/hr with an urea concentration of 35%.Also the results showed that urea injection with titanium dioxide as selective catalyst in the exhaust pipe caused a 68.5% NOx reduction for biodiesel which was achieved with a constant flow rate of 0.75lit/h with an urea concentration of 32.5%.Thus Biodiesel (C20) fuelled CI Engine with SCR is a very effective and suitable replacement for petroleum based diesel fuelled CI Engine with SCR. ANOVA analysis was done and resulted that the null hypothesis is rejected. A high p-value (0.104) had suggested that beta plays a less significant role in the model and a low p-value (0.012) suggests that beta plays a significant role in the model. Overall ANOVA analysis disclosed that percentage of urea solution has a major impact on NOX emissions than HC and CO emissions.

Probing Composition and Molecular Mobility in Thin Spherical Films Using Nuclear Magnetic Resonance Measurements of Diffusion

The composition and molecular mobility within thin spherical liquid films have been investigated using nuclear magnetic resonance (NMR) diffusion measurements. These films were formed either on the surface of pores inside a sponge at low saturation or by adsorbed water on the outside of urea prills during caking. Using pulsed field gradient (PFG) NMR experiments, the molecular mobility within these liquid films was determined through analysis of the conditional probability density for displacement (propagator). Molecular diffusion coefficients were determined for films in the sponge and prill systems by fitting the experimental propagators using a model for diffusion on an array of isotropically distributed infinite planes. By comparing these diffusion coefficients with bulk diffusion coefficients for a range of concentrations of urea solutions (2.1 M, 6.2 M and saturated), it was possible to optimize the PFG experimental parameters to enable accurate determination of molecular diffusion in these spherical liquid films. Determination of the diffusion coefficients for a range of urea solutions in the sponge enabled identification of the composition of the film that formed on the surface of the urea prills. Analysis of these data showed that the liquid layers are composed of saturated urea solution covering the surface of the prills, with an estimated layer thickness on the order of 10–5 m. The shape of the propagators indicated the adsorbed water was uniformly distributed over the surface of the urea prills, rather than primarily in the meniscus between particles, which agrees with dye visualization experiments on a pair of urea prills during caking. This work provides the first quantitative measurements of diffusion in thin spherical films, which is a key parameter for determining what controls the presence and rate of bonding between adjacent particle surfaces.

Fabrication of cost-effective surface enhanced Raman spectroscopy substrate using glancing angle deposition for the detection of urea in body fluid.

A surface enhanced Raman spectroscopy (SERS) with glancing angle deposited Ag nanorods structures was developed for the detection of urea in human serum. To maximize the SERS enhancement, the effects of Ag nanorod length on the SERS signal were analyzed. The SERS signals of different concentrations of urea solutions were measured in order to generate a regression model for use in analyzing the amount of urea in body fluid using the SERS substrate. To examine the feasibility of the fabricated SERS substrate, the amount of urea in human serum was measured using the SERS substrate and compared with that determined via conventional blood analysis.

Removal of Eggs Adhesiveness of African catfish (Clarias gariepinus) at Different Concentrations of Urea Solution

Abstract –The objective of the present study was to determine the best concentration of urea solution and rinsing time to remove adhesiveness of African catfish eggs. Four different concentrations of rinse solution were used in this experiment comprising of 2 g, 4 g, 6 g and 8 g of urea diluted in 4 g NaCl/L of water producing a concentration of 0.486 mM, 0.973 mM, 1.458 mM, and 1.946 mM of urea concentration respectively, while 4 g NaCl/L of water without urea were used as control. The fish eggs were rinsed with the solutions at different durations namely; 1, 5 and 10 minutes. Each rinsing solution concentration and rinsing time were conducted in three replicates. The fertilization and hatching rates increased and peaked from the control (0 mM of urea) to 0.466 mN urea and decreased when concentration of urea was increased to 0.973 mM urea and 1.458 mM urea, then increased again at 1.946 mM urea, but these values were lower than at 0.486 mM urea. Thus, the best concentration for fertilization and hatching rates were 0.486 urea of urea. However 0.973 mM of urea was optimum in reducing clumping of eggs. Keywords: Clumping; Fertilization; Hatching; Brood fish

Simultaneous Desulfurization and Denitrification from Flue Gas Using Urea/Piperazine Solution

The simultaneous desulfurization and denitrification performance from the N2-SO2-NO simulated flue gas using the urea solution as the reduction absorbent and piperazine as the additive was investigated. The influences of the concentration of urea solution and the concentration of piperazine solution on the simultaneous desulfurization and denitrification behavior were also discussed. The experimental results showed that the addition of piperazine in the urea solution could enhance the denitrification performance, which could result the desulfurization efficiency of 94.07% and the denitrification efficiency of 85.11%.