Role Of Urea Research Articles

Estimation of some Electrolytes in Kidney Disease Patients

Present case-control study explored the associations between the role of urea and creatinine levels in kidney patients. Sixty patients with chronic Kidney disease participated in this study; their age ranged from 28-60 years during the period from March 2019 until August 2019 at the National Hematological Center/ Al-Mustansiryah University. They were compared with 30 subjects as control group. A sample of 60 Iraqi patients were divided into two groups, the first over 50 years old were 42 samples, while the second group for patients under the age of 50 years recorded 18 samples, and the samples of healthy people recorded only 30 samples. Current study was designed to estimate the status of renal function in the blood and electrolytes in the serum were measured for all patients.

Supplemental nitrogen alleviates the negative effects of higher temperature on the vegetative growth of canola regardless of carbon dioxide concentration

Climate change components, including carbon dioxide (CO2) and temperature, can influence crop productivity and nutritional value, posing a threat to food security. Many studies have investigated the mitigation of climate change factors by nitrate and/or ammonium application, but there has been little focus on the role of urea in the interactive effects of these factors. We examined the effects of temperature, CO2, and supplemental nitrogen (N in the urea form) on growth and physiological traits of canola (Brassica napus). Plants were grown under two temperature regimes (22/18 °C and 28/24 °C, 16 h light/8 h dark), two CO2 concentrations (400 and 700 µmol mol−1), and three levels of N (zero, no supplement; low, based on 50 kg ha−1; high, based on 100 kg ha−1) for 21 days after one week of initial growth under 22/18 °C. In this study, gas exchange, chlorophyll fluorescence, chlorophyll, flavonoids, nitrogen balance index (NBI), plant growth and biomass, and tocopherols, were measured. Higher temperatures decreased net CO2 assimilation (AN), water use efficiency, effective quantum yield of photosystem II, nonphotochemical quenching (qNP), chlorophyll, flavonoids, stem height and diameter, leaf area and number, dry mass, and β-, γ-, and δ-tocopherols, but increased stomatal conductance. Elevated CO2 increased AN, qNP and leaf area ratio, but decreased stomatal conductance (gs). Supplemental nitrogen alleviated the effects of temperature stress by increasing gs, chlorophyll, NBI, stem height and diameter, leaf area, growth rate, and dry mass. Overall, these findings suggest that under climate change, N supplementation may be used to alleviate environmental stress on plants.

The likely role of urea in delaying the size at first maturity of ureosmotic Chondrichthyes

The likely role of urea in delaying the size at first maturity of ureosmotic Chondrichthyes

Ambient-dried, scalable and biodegradable cellulose nanofibers aerogel for oil-spill cleanup

Aerogels made of surface-modified cellulose nanofibers (CNF) have the potential to be a long-term solution for oil spill cleanup and industrial waste-water treatment, but their use is currently constrained by high preparation costs, lengthy processing times, and use of hazardous chemicals. In this study, a cost-effective and easily scalable cellulose nanofibers aerogel is developed using sugarcane bagasse as the cellulose source. The aqueous suspension of CNF and urea is freeze-thawed and then dried at ambient temperatures to produce CNF aerogels, avoiding the costly and time-consuming freeze-drying or supercritical drying methods. The role of urea in the aerogel structure is investigated using molecular dynamics. The aerogel exhibited an elastic modulus of 1345 KPa and a porosity of 96.9 %. To enhance the hydrophobicity of the surface of these aerogels, they are coated with the biodegradable polymer polycaprolactone (PCL). Further, two molecular weights (MW) PCL 10,000 and 80,000 are used to examine the impact of PCL MW on the performance and biodegradability of aerogel. Moreover, the efficacy of these green modifications is being compared to the conventional silane modifications. The 10,000 MW PCL-modified aerogel demonstrated a water-contact angle measuring 125.5°, an oil sorption capacity of 24 g/g, and exceptional recyclability even after undergoing 20 cycles. Further, after 15 days, the aerogel showed excellent biodegradability.

Role of urea in the retention of DON in soil by clay minerals: Analysis based upon molecular weight

As a widely used fertilizer, urea significantly promotes the leaching of dissolved organic nitrogen (DON) in soils and aggravates nitrogen contamination in groundwater. Clay minerals are considered the most important factor in retaining DON. However, the effect of urea on the retention of DON with different molecular weights by clay minerals is unknown. In this study, the retention of both low-molecular weight DON (LMWD) and high-molecular weight DON (HMWD) by clay minerals in the presence of urea was investigated. For this purpose, batch adsorption and soil column leaching experiments, characterization analysis (Fourier transform infrared spectroscopy X-ray diffraction, and X-ray photoelectron spectroscopy), and molecular dynamics simulations were carried out. Urea had a positive effect on the adsorption of LMWD, whereas a competitive effect existed for the adsorption of HMWD. The dominant interactions among DON, urea, and clay minerals included H-bonding, ligand exchange, and cation exchange. The urea was preferentially adsorbed on clay minerals and formed a complex, which provided more adsorption sites to LMWD and only a few to HMWD. The presence of urea increased the retention of LMWD and decreased the retention of HMWD in clay minerals. The retention capacity of LMWD increased by 6.9%–12.8%, while that of HMWD decreased by 6.7%–53.1%. These findings suggest that LMWD tended to be trapped in soils, while HMWD was prone to be leached into groundwater, which can be used to evaluate the leaching of DON from soil to groundwater.

The role of urea in formation of the sodium acetate trihydrate (SAT)-urea eutectic liquid: a neutron diffraction and isotopic substitution study.

Neutron diffraction with isotopic substitution has been used to investigate the structure of the liquid sodium acetate trihydrate-urea eutectic (mole fraction (χurea) of 0.60) at 50 °C. Urea competes with acetate anions and water molecules in the solvation of sodium ions, displacing water and, simultaneously, stabilising the liberated 'excess' water through hydrogen bonding between water and urea molecules in the eutectic liquid. This provides a direct insight into the role of urea as both denaturant and hydrogen-bond network former in generating eutectic liquids.

The role of urea on the dissolution of starch in NaOH-urea aqueous solutions.

Potato starch can be dissolved in NaOH-urea aqueous solutions to form a stable and homogeneous mixture to initiate further modification. The mechanism for the formation of such a solution was investigated by examining the interactions between urea and starch, using rheological tests, 13C NMR, FTIR, and a novel Kamlet-Taft solvation parameter analysis. It was found that the optimized dissolution condition was in aqueous 10% w/w NaOH-14% w/w urea, under which 97.4% light transmission was achieved. This was due to dispersive forces between urea and starch without the presence of strong hydrogen bond based interactions. DSC results further showed that the subtle dissolving facilitation of urea might be attributed to the heat released during urea hydrate formation. Compared with conventional hydrothermal gelatinized starch, the starch-NaOH-urea aqueous dispersion exhibited better stability. This highlighted the role of urea in forming a 'bridge' to combine starch with water molecules. This reduces the tendency for starch aggregation via its hydrophobic components. Intrinsic viscosity and GPC analysis indicated that the degradation of starch molecules was significantly reduced. This work provides new insights into the role of urea in starch-NaOH-urea aqueous dispersion. This type of starch solvent formulation will have significant potential for further preparation of starch-based materials for various applications.

The role of urea in regulating the structural properties of Zr–Sn-based oxide catalysts for direct synthesis of dimethyl carbonate from CO2 and methanol

Zr–Sn–O catalysts were prepared with urea as precipitant. It was found that the usage of urea had a crucial effect on the structure properties and the catalytic activity of direct synthesis of DMC from CO2 and methanol.

Role of urea on the structural, textural, and optical properties of macroemulsion-assisted synthesized holey ZnO nanosheets for photocatalytic applications

The photocatalytic activity of holey ZnO nanosheets was observed using time-dependent photoluminescence (PL) spectroscopy with photodegradation kinetic determined from the PL intensity decay follows the first-order reaction kinetic.

352 A Century and a Half of Nitrogen and Protein Metabolism in Ruminants

Abstract By 1870, we knew plants and animals contained protein, and the participation of protein and urea in animal and human N metabolism was recognized. Nitrogen balance studies had been conducted, and the atomic theory was established. By 1900, research established the concepts of energy and protein metabolic interactions, the role for urea in ruminant metabolism, amino acids as constituents of protein molecules, and enzyme-catalyzed reactions. Research stations were publishing research results and feeding recommendations. By 1950, the concept of biological value was established, and we knew ruminal microorganisms use dietary NPN, degrade dietary protein, and form microbial protein as a source of amino acids for ruminant tissue protein. By 2000, hypothesis-driven, statistically valid experimental designs created quantitative information on metabolizable protein and essential amino acid requirements. Use of surgically altered animals, isotopically labelled molecules, and standardized laboratory analyses created quantitative information on ingestion, ruminal degradability of dietary protein, digestion, absorption, and metabolism of N-containing compounds. Research showed that ruminants respond to manipulation of postruminal amino acid supply. We had elucidated protein composition and structure, the role of protein turnover to determine the concentration of cellular proteins, and the quantitative significance of protein turnover to whole body protein metabolism. The internet and the advent of international symposia provided links among researchers around the globe. By 2020, proteomics and metabolomics enhanced description of underlying control mechanisms related to amino acid metabolism. Research quantified integration of amino acid supply and use among body tissues. Multidisciplinary research teams had created empirical and mechanistic models. Those models currently use or estimate rates and daily amounts of ruminal (in)degradability of dietary protein, ammonia production, urea recycling, microbial protein synthesis, postruminal protein digestion, metabolic fecal nitrogen, and amino acid absorption and metabolism. They predict use of metabolizable amino acids for maintenance, reproduction, postnatal growth, and lactation.

Salinity Tolerance and Osmoregulation in the Wide-spread Pacific Treefrog, Pseudacris regilla

The effects of high saline concentrations on the plasma osmolytes of the four populations of the Pacific Treefrog, Pseudacris regilla, were investigated. Two of the populations, Chris Wicht and Trabuco Canyon, were in fresh water environments and two populations, Newport Back Bay and Alkaline Marsh, were in brackish water environments. The Newport Backbay treefrogs were most tolerant of increased sodium chloride solutions with 11 of 15 individuals surviving at 240 mM sodium chloride at 72 hrs. The Trabuco Canyon population was the least tolerant with 10 of 15 specimens surviving 120 mM sodium chloride at 72 hrs but none at the 180 mM concentration at 72 hrs. The Chris Wicht and Alkaline Marsh treefrogs were intermediate in their survival times with frogs surviving in 180 mM saline solutions at 72 hrs. The Newport treefrogs appeared to be the most efficient in osmoregulating by mainstreaming the plasma sodium and increasing plasma urea to compensate for the osmotic gradient produced by the increased external saline concentrations. The Trabuco Canyon and the Chris Wicht treefrogs appeared to be intermediate in their osmoregulatory abilities with the Alkaline Marsh treefrogs being least efficient and more likely an osmoconformer. The difference in osmoregulatory responses appears to be a population difference and a function of habitat. Sodium chloride was the major plasma osmolyte in the four populations of treefrogs. Urea increased in importance as the external concentration of the saline media increased, thus the role of urea was significant in maintaining the internal osmoconcentration. These simple physiological mechanisms allow this widespread treefrog to occur in so many different habitats.

On New Substances of Urea Derivatives Obtained by the Quantum-mechanical Method ab Initio, Their Structural-geometric, Charge and Energy Properties

The body of humans and animals contains large quantities of urea, which is believed to serve as an excretory agent for removing excess protein in it. With regard to the toxicity of this substance in the body there is no clarity, whether it is a uremic toxin, or whether this substance is not toxic. It is possible that the role of urea in the body is connected with its metabolites. It is known that there are substances that are derivatives of urea, which exhibit high biological activity. Instance, the well-known carbamide derivative, hydroxycarbamide has gained recognition as an important anticancer drug and an effective promising therapeutic agent for sickle cell anemia. The discovery of new substances and the establishment of their properties is an important task of science, both theoretical and practical. Urea can be a source of new substances, urea derivatives with interesting properties. The aim of the work was, on the basis of quantum mechanical studies, to find out the fundamental possibility of the existence of other urea-derived substances and some other substances of a similar nature and to carry out a comparative analysis of their properties in terms of the interaction of their molecules with water molecules and with each other. In this work, the possibility of the existence of many substances that are derivatives of urea was discovered. Regarding the new urea-derived substances discovered by us, they can be divided into two groups of substances, substances containing a carbohydroxyl group in their composition and substances not containing it. Among the discovered new substances containing a karbohydroxyl group, a substance was found that is an isomer of urea. Based on the quantum mechanical approach, a comparative analysis of the structure, charge and energy properties of carbamide, hydroxycarbamide, and a number of new virtually synthesized carbamide derivatives is carried out. The work shows how the molecules of these substances interact with each other and with water molecules. Numerical values of geometric, charge and energy characteristics of new substances are given and the results obtained are discussed.

Hydrogen generation from the reaction of Al and H2O using a synthesized Al(OH)3 nanoparticle catalyst: the role of urea

This research investigated the high catalytic activity of different crystalline phases of Al(OH)3 nano-particles (NPs) for hydrogen generation from the Al/water reaction.

Review on role of urea and thiourea derivatives of some heterocyclic Scaffold in drug design and medicinal chemistry

Compounds comprising urea and thiourea are progressively more used in drug design and medicinal chemistry to facilitate key drug-target communications and fine-tune crucial drug-like properties. Urea and thiourea represent privileged structures in medicinal chemistry. Certainly, these scaffolds encompass a common structure of a array of drugs and bioactive compounds artistic with a expansive range of beneficial and pharmacological properties. Herein, we provide an overview of urea and thiourea based medicinally important compounds, ranging from standard drugs to current medicinal chemistry developments.

Promotion mechanism for the growth of CO2 hydrate with urea using molecular dynamics simulations.

The role of urea as a kinetic promoter for the growth of CO2 hydrates is revealed for the first time using molecular dynamics simulations. Analysis of simulation trajectories shows that urea plays two important roles in the growth process: increasing mass transport of CO2 and catalyzing cage formation at the solid-liquid interface.

Phenotypical evidence of effective amelioration of ammonium-inhibited plant (root) growth by exogenous low urea

Ammonium and nitrate are major soil inorganic-nitrogen sources for plant growth, but many species cultivated with even low millimolar NH4+ as a sole N form display a growth retardation. To date, critical biological components and applicable approaches involved in the effective enhancement of NH4+ tolerance remain to be thoroughly explored. Here, we report phenotypical traits of urea-dependent improvement of NH4+-suppressed plant/root growth. Urea at 0.1 mM was sufficient to remarkably stimulate NH4+ (3 mM)-fed cotton growth, showing a 2.5∼4-fold increase in shoot- and root-biomass and total root-length, 20 % higher GS activity, 18 % less NH4+-accumulation in roots, and a comparable plant total-N content compared to the control, implying a novel role for urea in cotton NH4+detoxification. A similar phenomenon was observed in tobacco and rice. Moreover, comparisons between twelve NH4+-grown Arabidopsis accessions revealed a great degree of natural variation in their root-growth response to low urea, with WAR and Blh-1 exhibiting the most significant increase in primary- and lateral-root length and numbers, and Sav-0 and Edi-0 being the most insensitive. Such phenotypical evidence suggests a common ability of plants to accommodate NH4+-stress by responding to exogenous urea, providing a novel aspect for further understanding the process of urea-dependent plant NH4+ tolerance.

A fluorescence approach on the investigation of urea derivatives interaction with a non-PET based acridinedione dye-beta Cyclodextrin (β-CD) complex in water: Hydrogen-bonding interaction or hydrophobic influences or combined effect?

Photophysical studies of resorcinol based acridinedione dyes with beta Cyclodextrin (β-CD) in the presence of urea (U) and tetramethylurea (TMU) were carried out in water. A marked variation in the absorption spectra of dye-β-CD complex was found to be more significant in the case of U rather in TMU. Interestingly, the role of urea on the excited state behavior of dye-β-CD complex is found to be entirely different from that of TMU. The formation of urea-water hydrogen-bonding self assemblies and creation of microspheres of varying environment results in an effective displacement of dye from the hydrophobic nanocavity of β-CD. On the contrary, the dye prefers a more confined hydrophobic micro environment in the presence of TMU. The nature of urea derivative, hydrogen-bonding of urea-water assemblies and hydrophobic influences of methyl moieties in urea molecular framework governs the stability and also the dissociation of dye-β-CD complex. The displacement of dye from the environment of the sugar molecule by urea derivatives is established from fluorescence studies wherein the variation in the spectral behavior of non-PET based dye-β-CD complex is found to be entirely different from that of PET dye. Both hydrogen-bonding along with hydrophobic interactions influences the excited state properties of the both PET and non-PET based acridinedione dyes are elucidated through fluorescence spectral studies. The extent of binding and the microenvironment of the dye in the presence of β-CD and urea are established through molecular docking and fluorescence anisotropy studies.

THU156 - The role of urea on the prognosis of severe acute liver injury and acute liver failure

THU156 - The role of urea on the prognosis of severe acute liver injury and acute liver failure

The role of urea in the solubility of cellulose in aqueous quaternary ammonium hydroxide.

We examine the role of water and urea in cellulose solubility in tetrabutylammonium hydroxide (TBAH). Molecular dynamics simulations were performed for several different solvent compositions with a fixed cellulose fraction. For each composition, two simulations were carried out with cellulose fixed in each of the crystalline and the dissolved states. From the enthalpy and the entropy of the two states, the difference in Gibbs free energy (ΔG) and hence the spontaneity is determined. A comparison with solubility experiments showed a strong correlation between the calculated ΔG and the experimental measurements. A breakdown of the enthalpic and entropic contributions reveals the roles of water and urea in solubility. At high water concentration, a drop in solubility is attributed to both increased enthalpy and decreased entropy of dissolution. Water displaces strong IL–cellulose interactions for weaker water–cellulose interactions, resulting in an overall enthalpy increase. This is accompanied by a strong decrease in entropy, which is primarily attributed to both water and the entropy of mixing. Adding urea to TBAH(aq) increases solubility by an addition to the mixing term and by reducing losses in solvent entropy upon dissolution. In the absence of urea, the flexible [TBA]+ ions lose substantial degrees of freedom when they interact with cellulose. When urea is present, it partially replaces [TBA]+ and to a lesser extent OH− near cellulose, losing less entropy because of its rigid structure. This suggests that one way to boost the dissolving power of an ionic liquid is to limit the number of degrees of freedom from the outset.

Bi(nanoparticles)/CNx(nanosheets) nanocomposites as high capacity and stable electrode materials for supercapacitors: the role of urea.

The evolution of high-performance and stable electrode materials for supercapacitors plays a vital role in the next generation of energy storage devices. In this work we present a simple method for preparing Bi(nanoparticles)/CNx(nanosheets) nanocomposites as electrode materials for supercapacitors, which were synthesized by thermally treating bismuth citrate and urea at 550-700 °C under an Ar atmosphere. According to physicochemical studies (XRD, SEM, TG-DTA, XPS, FTIR, and BET), a "smeared" bismuth formation or the formation of nanoparticles on the CNx surface of interwoven 2D-nanosheets at different calcination temperatures was observed. Electrochemical measurements show that the specific capacity of the composites can reach 1251 F g-1 (more than 90% of the theoretical value) at a current density of 500 mA g-1 in a 6 M KOH electrolyte, and most two-dimensional CNx-based nanostructures remain intact after multiple galvanostatic charge-discharge processes, which is promising for the development of highly efficient supercapacitors. A supercapacitor composed of Bi/CNx nanocomposites for the negative electrode and Ni-layered hydroxide for the positive electrode demonstrates a high energy density of 58 W h kg-1 with a power density of 800 W kg-1 accompanied by a good cycle life (the parameters decreased down to only 78% after 1000 charge-discharge cycles). Our current results indicate that the addition of urea not only determines the morphology of the composites, but also lays the foundation for the development of new types of nanocomposites for the power industry.