Showing papers on "Urea published in 2019"
126 citations
TL;DR: It is concluded that use of CRU should be encouraged for maize production, especially on light-textured soils with low organic matter content, and in soils with pH ≥ 6.0.
100 citations
TL;DR: In this paper, the effect of urea concentration on carbonate precipitation was studied by changing the urea concentrations that was added during inoculation, and the results showed that at high temperature, the growth rate of B. megaterium was close to that of S. pasteurii, while the opposite result was found at low temperature.
Abstract: Temperature is a key factor that contributes to microbially induced calcium carbonate precipitation. At low temperatures, low enzyme activity results in a lack of calcium precipitation. In this study, Sporosarcina pasteurii and Bacillus megaterium were compared. Firstly, the optical density curves and enzyme activity curves of both bacteria were obtained during 48-h culture. Then, optical density, enzyme activity, and productive rates for calcium carbonate were measured to analyze the influence of temperature. Finally, the effect of urea concentration on carbonate precipitation was studied by changing the urea concentration that was added during inoculation. The obtained results showed that at high temperature, the growth rate of B. megaterium was close to that of S. pasteurii, while the opposite result was found at low temperature. The urease activities of B. megaterium were similar at different temperature conditions. At high temperature, B. megaterium showed lower enzyme activity, while at low temperature, it surpassed that of S. pasteurii. The same results were found for enzyme activity and for the precipitation rates of calcium carbonate. The addition of urea to the medium increased precipitation rates, and higher urea concentrations increased the obtained precipitation rates. With 20 g/L urea, the precipitation rate of B. megaterium at 15 °C matched that without urea addition at 30 °C. Therefore, adding urea to the medium at the time of inoculation can effectively overcome the low calcium precipitation at low temperature and enable subsequent low-temperature engineering applications.
92 citations
24 May 2019
TL;DR: The UOR reaction is a key half-reaction in assembling the direct urea fuel cells (DUFCs) to generate electricity, or constructing a urea electrolyzer to convert electrically urea to fuel cells as mentioned in this paper.
Abstract: Electrocatalytic urea oxidation reaction (UOR) is a key half-reaction in assembling the direct urea fuel cells (DUFCs) to generate electricity, or constructing a urea electrolyzer to convert electr...
84 citations
TL;DR: It is demonstrated that in the Gulf of Mexico, Thaumarchaeota use urea and cyanate both directly and indirectly as energy and N sources, and hypothesize that ureaand cyanate are substrates for ammonia-oxidizing Thaum archaeota throughout the ocean.
Abstract: Ammonia-oxidizing archaea of the phylum Thaumarchaeota are among the most abundant marine microorganisms1. These organisms thrive in the oceans despite ammonium being present at low nanomolar concentrations2,3. Some Thaumarchaeota isolates have been shown to utilize urea and cyanate as energy and N sources through intracellular conversion to ammonium4–6. Yet, it is unclear whether patterns observed in culture extend to marine Thaumarchaeota, and whether Thaumarchaeota in the ocean directly utilize urea and cyanate or rely on co-occurring microorganisms to break these substrates down to ammonium. Urea utilization has been reported for marine ammonia-oxidizing communities7–10, but no evidence of cyanate utilization exists for marine ammonia oxidizers. Here, we demonstrate that in the Gulf of Mexico, Thaumarchaeota use urea and cyanate both directly and indirectly as energy and N sources. We observed substantial and linear rates of nitrite production from urea and cyanate additions, which often persisted even when ammonium was added to micromolar concentrations. Furthermore, single-cell analysis revealed that the Thaumarchaeota incorporated ammonium-, urea- and cyanate-derived N at significantly higher rates than most other microorganisms. Yet, no cyanases were detected in thaumarchaeal genomic data from the Gulf of Mexico. Therefore, we tested cyanate utilization in Nitrosopumilus maritimus, which also lacks a canonical cyanase, and showed that cyanate was oxidized to nitrite. Our findings demonstrate that marine Thaumarchaeota can use urea and cyanate as both an energy and N source. On the basis of these results, we hypothesize that urea and cyanate are substrates for ammonia-oxidizing Thaumarchaeota throughout the ocean. Thaumarchaeota isolates are capable of utilizing urea and cyanate for nitrification in vitro. Here, the authors show that this occurs in situ and that Thaumarchaeota are able to use urea and cyanate as an energy and nitrogen source in the marine environment.
83 citations
TL;DR: Urea electrolysis is a promising route to utilize urea-rich wastewater as an energy source to produce hydrogen on the cathode or generate electricity through a direct urea fuel cell, which offers g...
Abstract: Urea electrolysis is a promising route to utilize urea-rich wastewater as an energy source to produce hydrogen on the cathode or generate electricity through a direct urea fuel cell, which offers g...
82 citations
TL;DR: In this article, the catalytic ability of nickel-molybdenum oxide nanorods for urea electro-oxidation was investigated and the performance of urea oxidation and kinetics analysis were measured by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy.
79 citations
73 citations
TL;DR: It is successfully showed that human urine can be used to manufacture bio-bricks thus offering an additional use of human urine.
73 citations
TL;DR: In this paper, the NiCo2O4/NF electrode was used for the oxidation of urea in alkaline solution using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) measurements, which showed that the as-prepared Ni foam substrate exhibits homogeneous and porous nanowire arrays, providing a number of active sites and electronic transmission channels for urea electrooxidation.
72 citations
TL;DR: The results suggested the as-prepared fertilizer had good abilities to retain water and control urea release, and the addition of halloysite helped to improve the release properties of the fertilizer.
TL;DR: In this article, the priming effect of combined biochar and urea inputs on soil inorganic N pools through an isotope tracer approach was investigated, and it was found that biochar may partially offset the mineralization of easily available organic C, buffering the immobilization of inorganic n in soil when labile organic compounds (e.g. root exudates, fresh manure, etc.) are incorporated.
Abstract: Biochar has been found to interact with N transformations in soil but the mechanisms remain largely unknown. In this study we investigated the priming effect of combined biochar and urea inputs on soil inorganic N pools through an isotope tracer approach. Biochar was applied in combination with urea in two complementary laboratory experiments: (i) in the first one, three 15N-labeled organic amendments (wheat straw (WS)), its biochars produced at 350 °C (B350) and at 550 °C (B550) were added to soil in combination with unlabeled urea; (ii) in the second experiment the three same, but unlabeled, amendments were added to soil in combination with 15N labeled urea. This system allowed partitioning between three N sources: native soil N, biochar-derived N and urea-derived N. In addition, CO2 fluxes were measured to follow total C mineralization in soil and N2O emissions were monitored. The proportion of N that mineralized from biochar was always below 0.5% of the added N. The co-addition of urea increased the concentration of NH4+ derived from B350, but not from B550, demonstrating the lower mineralization of N in biochars produced at 550 °C. Whereas the addition of WS led to a rapid immobilization of N, we found that despite their high C:N, none of the biochars, applied at a rate of 1.5%, immobilized inorganic N in soil. On the contrary, significantly higher NH4+concentrations derived from native soil organic N (SON) and urea were found throughout the incubation when B550 was added. This effect can be attributed to an apparent priming effect since a net decrease in CO2 fluxes was recorded when biochar was added to the soil. The addition of glucose (a low molecular weight carbon source) stimulated an increase in CO2 fluxes in all treatments along with a net N immobilization in soil. However, both biochars significantly reduced C readily available to microbes, as proved by lower soil CO2 fluxes, and limited the immobilization of NH4+ induced by glucose addition. Our results suggest that biochar may partially offset the mineralization of easily available organic C, buffering the immobilization of inorganic N in soil when labile organic compounds (e.g. root exudates, fresh manure, etc.) are incorporated.
29 Apr 2019-Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment
TL;DR: It is revealed that SERS based on coffee ring effect has the potential to be further exploited for detecting other banned and hazardous adulterants in milk and milk products.
Abstract: In the current work, surface-enhanced Raman scattering (SERS) based on gold nanoparticles (AuNPs) and silver-coated gold nanoparticles (Au@AgNPs) with coffee ring effect was employed to simultaneously ascertain urea and ammonium sulfate (AmS) in milk. A small drop (2 µL) of milk with adulterants was dried on a gold-coated slide to examine concentrations ranging from 5, 10, 20, 40 and 80 mg/dL based on spectra ranging from 400 to 1500 cm.-1 A uniform distribution of analytes, with enhanced Raman signals was detected in a small region (maximum 1.9 mm) of coffee ring across the centre of coffee ring pattern. Nanoparticles with core (Au) diameter of 26 nm and shell thickness (Ag) of 6.5 nm were confirmed using transmission electron microscopy (TEM) images. A strong Raman peak at 980 cm-1 was assigned to AmS, while that at 1001 cm-1 was ascribed to urea. With AuNPs, coefficients of determination (R2) of 0.9873 and 0.9859 were achieved for urea and AmS, respectively, while for Au@AgNPs values of 0.9827 and 0.9855 were obtained for urea and AmS, respectively. This study revealed that SERS based on coffee ring effect has the potential to be further exploited for detecting other banned and hazardous adulterants in milk and milk products.
TL;DR: The hypothesis that urea may also act as a carbon (C) source to supplemental growth requirements during the alkaline conditions created by dense cyanobacterial blooms, when concentrations of dissolved CO2 are vanishingly low is tested.
Abstract: The use of urea as a nitrogenous fertilizer has increased over the past two decades, with urea itself being readily detected at high concentrations in many lakes. Urea has been linked to cyanobacterial blooms as it is a readily assimilated nitrogen (N) - source for cyanobacteria that possess the enzyme urease. We tested the hypothesis that urea may also act as a carbon (C) source to supplemental growth requirements during the alkaline conditions created by dense cyanobacterial blooms, when concentrations of dissolved CO2 are vanishingly low. High rates of photosynthesis markedly reduce dissolved CO2 concentrations and drive up pH. This was observed in Lake Erie during the largest bloom on record (2015) over long periods (months) and short periods (days) of time, suggesting blooms experience periods of CO2-limitation on a seasonal and daily basis. We used 13C-urea to demonstrate that axenic cultures of the model toxic cyanobacterium, Microcystis aeruginosa NIES843, assimilated C at varying environmentally relevant pH conditions directly into a spectrum of metabolic pools during urea hydrolysis. Primarily, 13C from urea was assimilated into central C metabolism and amino acid biosynthesis pathways, including those important for the production of the hepatotoxin, microcystin, and incorporation into these pathways was at a higher percentage during growth at higher pH. This corresponded to increased growth rates on urea as the sole N source with increasing pH. We propose this ability to incorporate C from urea represents yet another competitive advantage for this cyanobacterium during dense algal blooms.
TL;DR: In this paper, the solubilities of ammonia (NH3) in deep eutectic solvents (DESs) comprising of choline chloride (ChCl) and urea at the temperature ranging from (2982 to 3532)
TL;DR: Biorenewable poly(γ-butyrolactone) with a high molecular weight was prepared with a base/urea binary synergistic catalyst and its application in high-performance liquid chromatography showed promising results.
TL;DR: In this article, a co-precipitation method was used to construct NiCoPO with different Ni/Co ratio for catalytic electro-oxidation of methanol or urea.
TL;DR: Compared the four commonly used extraction methods and highlighted both physical and chemical differences in the extracted keratin, keratin extracted from peracetic acid method exhibited secondary structural conformation similar to thioglycolic acid method provided new insight into the extraction of keratin from human hair.
TL;DR: UV/VUV is an effective alternative for urea removal from SPW and yielded nitrate and ammonia as the key products with the mass balance of nitrogen element being met.
TL;DR: The bubbling-type photosynthetic algae microbial fuel cell (B-PAMFC) to treat synthetic wastewater and capture CO2 using Chlorella vulgaris with simultaneous power production and nitrogen source would provide an attractive strategy for simultaneous CO2 sequestration and bioenergy production.
TL;DR: Porous and hollow Ni0.9Fe0.1Ox microspheres assembled from 2D nanosheets exhibit excellent bifunctional activity for both urea oxidation reaction and hydrogen evolution reaction, in which the potential for overall urea splitting is 1.455 V at 10 mA cm-2.
TL;DR: In this paper, the authors used biochemical, molecular genetic and physiological approaches to demonstrate that PII regulates all relevant nitrogen uptake systems in Synechocystis sp. strain PCC 6803.
Abstract: PII signal transduction proteins are widely spread among all domains of life where they regulate a multitude of carbon and nitrogen metabolism related processes. Non-diazotrophic cyanobacteria can utilize a high variety of organic and inorganic nitrogen sources. In recent years, several physiological studies indicated an involvement of the cyanobacterial PII protein in regulation of ammonium, nitrate/nitrite, and cyanate uptake. However, direct interaction of PII has not been demonstrated so far. In this study, we used biochemical, molecular genetic and physiological approaches to demonstrate that PII regulates all relevant nitrogen uptake systems in Synechocystis sp. strain PCC 6803: PII controls ammonium uptake by interacting with the Amt1 ammonium permease, probably similar to the known regulation of E. coli ammonium permease AmtB by the PII homolog GlnK. We could further clarify that PII mediates the ammonium- and dark-induced inhibition of nitrate uptake by interacting with the NrtC and NrtD subunits of the nitrate/nitrite transporter NrtABCD. We further identified the ABC-type urea transporter UrtABCDE as novel PII target. PII interacts with the UrtE subunit without involving the standard interaction surface of PII interactions. The deregulation of urea uptake in a PII deletion mutant causes ammonium excretion when urea is provided as nitrogen source. Furthermore, the urea hydrolyzing urease enzyme complex appears to be coupled to urea uptake. Overall, this study underlines the great importance of the PII signal transduction protein in the regulation of nitrogen utilization in cyanobacteria.
TL;DR: In this paper, five different binders, namely corn starch, potato starch, bentonite clay, white cement, and acrylic polymer were used in fabricating zeolite-coated urea CRF using a pan granulator at different operational conditions.
Abstract: Zeolite is the most widely used coating material in developing controlled release fertilizers (CRF) due to low cost and its inherent cation exchange property that effectively controls the nutrient release rate. Using an appropriate binder is the key in fabricating structurally stable zeolite based CRF due to the poor binding behavior of zeolite. In this research, five different binders, namely corn starch, potato starch, bentonite clay, white cement, and acrylic polymer were used in fabricating zeolite coated urea CRF using a pan granulator at different operational conditions. The fabricated CRFs (using five different binders) were characterized by particle size distribution (PSD), structural stability, crushing strength, elemental analysis, Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Nitrogen release rate from the CRFs was investigated by laboratory studies. The zeolite coated urea with acrylic polymer binder (UZ-AP) was found to be structurally stable with high crushing strength. The SEM analysis revealed that UZ-AP had dense coating and tiny pores with 135- 150 μ m coating thickness. The FT-IR analysis predicted the hydrophilic nature of the CRF. The UZ-AP controlled the nitrogen release by 54.7% compared to other CRFs. Thirty days soil column study for UZ-AP and urea concluded that leaching of nitrogen decreased by 65% compared to urea fertilizer. This newly developed zeolite coated urea could be a potential nitrogen fertilizer with controlled release property for efficient crop nitrogen management.
TL;DR: A series of lanthanide nitrate hydrate:urea "Type IV" deep eutectic solvents (DES; Ln = Ce, Pr, Nd) were prepared and their physical properties measured, showing very high surface tension and densi...
Abstract: A series of lanthanide nitrate hydrate:urea “Type IV” deep eutectic solvents (DES; Ln = Ce, Pr, Nd) were prepared and their physical properties measured, showing very high surface tension and densi...
TL;DR: In this article, the authors compared the ammonia losses of surface-applied urea (UR) and N-(n-butyl) thiophosphoric triamide (NBPT) fertilizers and showed that NBPT-UR and PSCUR could substitute for UR, aiming to mitigate ammonia volatilization.
24 Oct 2019
TL;DR: In this article, a two-step process of forward osmosis (FO) and membrane distillation (MD) was developed to recover the urea in fresh human urine.
Abstract: Urea is widely used as fertilizer and has other valuable uses such as diesel exhaust fluid and for resin fabrication. Human urine is a readily available and local source of urea that is overlooked due to the rapid hydrolysis of urea in fresh urine and wastewater, which makes its recovery challenging. Moreover, urea is a compound without an established method for recovery from urine or other waste streams. In this research, a novel two-step process of forward osmosis (FO) and membrane distillation (MD) was developed to recover the urea in fresh human urine. Specifically, FO was used to selectively separate urea from the other components in urine and MD was used to concentrate the separated urea. Five pre-treatment conditions were investigated for urea stabilization. For samples of fresh urine, fresh urine with acetic acid, fresh urine with calcium hydroxide, fresh urine with sodium hydroxide, and synthetic fresh urine with sodium hydroxide, FO recovered 20%, 15%, 12%, 11%, and 21% of the urea in urine, respectively. MD was able to concentrate the product draw solutions from FO containing urea by a factor of 1.9 to 3.3. The combined process was able to produce a product solution that had an average urea concentration that is 45–68% of the urea concentration found in the fresh urine with greater than 90% rejection of TOC. The proof-of-concept study illustrated that FO–MD provides a technology platform for urea recovery from fresh human urine, which currently does not have an established method for recovery.
TL;DR: Ni100-xRhx/C composites consisting in bimetallic nanoparticles dispersed in high surface area graphite were synthesized and their electrocatalytic performances for urea oxidation tested in alkaline media by cyclic voltammetry using a cavity microelectrode as mentioned in this paper.
TL;DR: In this article, a urea-based multipoint hydrogen-bond donor additive leads to an enhancement in activity for electrochemical CO2 reduction to CO catalyzed by Ni cyclam without altering this catalyst's high selectivity for CO2 versus proton reduction.
TL;DR: A novel hydrogel-based biosensor for the detection of urea with a high long-term stability over at least eight weeks and is highly selective to urea in comparison to similar species like thiourea or N-methylurea.
Abstract: Urea is used in a wide variety of industrial applications such as the production of fertilizers. Furthermore, urea as a metabolic product is an important indicator in biomedical diagnostics. For these applications, reliable urea sensors are essential. In this work, we present a novel hydrogel-based biosensor for the detection of urea. The hydrolysis of urea by the enzyme urease leads to an alkaline pH change, which is detected with a pH-sensitive poly(acrylic acid-co-dimethylaminoethyl methacrylate) hydrogel. For this purpose, the enzyme is physically entrapped during polymerization. This enzyme-hydrogel system shows a large sensitivity in the range from 1 mmol/L up to 20 mmol/L urea with a high long-term stability over at least eight weeks. Furthermore, this urea-sensitive hydrogel is highly selective to urea in comparison to similar species like thiourea or N-methylurea. For sensory applications, the swelling pressure of this hydrogel system is transformed via a piezoresistive pressure sensor into a measurable output voltage. In this way, the basic principle of hydrogel-based piezoresistive urea biosensors was demonstrated.
TL;DR: In this paper, a soil column experiment was conducted to examine the effects of fertilizer source and depth of placement on soil profile N2O accumulation and surface emissions at 44% and 77% water-filled pore space (WFPS).
Abstract: A soil column experiment was conducted to examine the effects of fertilizer N source and depth of placement on soil profile N2O accumulation and surface emissions at 44% and 77% water-filled pore space (WFPS). The used N fertilizers were polymer-coated urea, stabilized urea with urease and nitrification inhibitors, and conventional granular urea. Conventional urea and stabilized urea were applied either uniformly at 0–65 cm or deeply at a 40- to 65-cm depth of 65 cm repacked soil columns, whereas polymer-coated urea was subsurface banded at a 10-cm depth to reflect fertilizer application practices at a field scale. Profile N2O concentrations at 5, 15, 30, and 60 cm and surface flux were monitored over 3 months. Compared to conventional urea, stabilized urea and polymer-coated urea generally reduced N2O accumulation in the column, but not cumulative emissions. Across fertilizer sources, compared with uniform addition, deep placement reduced column N2O accumulation at 44% but not at 77% WFPS. Deep placement also reduced emissions 56–71% than for uniform placement. Column N2O accumulation doubled at 77% than 44% WFPS, whereas cumulative emissions and applied N–based emission factors were lower at the former WFPS value. Cumulative N2O emissions increased exponentially with total accumulation at 44% but not 77% WFPS. Reduced N2O emissions at high WFPS were likely due to consumption and low diffusivity of the gas in the soil profile, rather than low production by denitrification. These results suggest fertilizer N leached down the profile is less prone to N2O loss while emission reductions by using more efficient fertilizers may be limited.