Ratio Of Urea Research Articles

Urea Glass Route as a Way to Optimize YAGG:Ce3+,Cr3+,Pr3+ Nanocrystals for Persistent Luminescence Applications.

A new approach for the synthesis of Y3Al2Ga3O12 (YAGG) nanophosphors allowing the preparation of crystallites with sizes starting from 45 nm is presented. The controllability of the energy and trap density of the resulting material samples by annealing temperature was confirmed by thermoluminescence (TL) measurements. It has been shown that the annealing of samples at temperatures up to 1300 °C does not cause any substantial growth of crystallites, still remaining below 100 nm, but leads to changes in the activation energy of the persistent luminescence (PersL) process. On the other hand, annealing above 1400 °C results in grain growth on the submicron scale, which was confirmed by X-ray powder diffraction (XRPD) and electron transmission microscopy (TEM) measurements. In addition, with an increase in the molar ratio of urea to the total amount of metals used (R), qualitative changes are observed in the PersL process occurring from the excited states of Cr3+ and Pr3+ ions. This proves the influence of the synthesis process, in particular of the metal complexation at its initial stage, on the final structure ordering in the annealed materials. These observations are linked to previously reported defects in the YAGG structure, leading to PersL.

Nuclear Magnetic Resonance Spectroscopy Metabolomics in Idiopathic Intracranial Hypertension to Identify Markers of Disease and Headache.

We evaluated the metabolomic profile in the CSF, serum, and urine of participants with idiopathic intracranial hypertension (IIH) compared with that in controls and measured changes in metabolism associated with clinical markers of disease activity and treatment. A case-control study compared women aged 18-55 years with active IIH (Friedman diagnostic criteria) with a sex-matched, age-matched, and body mass index-matched control group. IIH participants were identified from neurology and ophthalmology clinics from National Health Service hospitals and underwent a prospective intervention to induce disease remission through weight loss with reevaluation at 12 months. Clinical assessments included lumbar puncture, headache, papilledema, and visual measurements. Spectra of the CSF, serum, and urine metabolites were acquired using proton nuclear magnetic resonance spectroscopy. Urea was lower in IIH participants (CSF, controls median ± IQR 0.196 ± 0.008, IIH 0.058 ± 0.059, p < 0.001; urine, controls 5971.370 ± 3021.831, IIH 4691.363 ± 1955.774, p = 0.009), correlated with ICP (urine p = 0.019) and headache severity (CSF p = 0.031), and increased by 12 months (CSF 12 months; 0.175 ± 0.043, p = 0.004, urine; 5210.874 ± 1825.302, p = 0.043). The lactate:pyruvate ratio was increased in IIH participants compared with that in controls (CSF, controls 49.739 ± 19.523, IIH 113.114 ± 117.298, p = 0.023; serum, controls 38.187 ± 13.392, IIH 54.547 ± 18.471, p = 0.004) and decreased at 12 months (CSF, 113.114 ± 117.298, p < 0.001). Baseline acetate was higher in IIH participants (CSF, controls 0.128 ± 0.041, IIH 0.192 ± 0.151, p = 0.008), correlated with headache severity (p = 0.030) and headache disability (p = 0.003), and was reduced at 12 months (0.160 ± 0.060, p = 0.007). Ketones, 3-hydroxybutyrate and acetoacetate, were altered in the CSF at baseline in IIH participants (3-hydroxybutyrate, controls 0.074 ± 0.063, IIH 0.049 ± 0.055, p = 0.019; acetoacetate, controls 0.013 ± 0.007, IIH 0.017 ± 0.010, p = 0.013) and normalized at 12 months (0.112 ± 0.114, p = 0.019, 0.029 ± 0.017, p = 0.015, respectively). We observed metabolic disturbances that are evident in the CSF, serum, and urine of IIH participants, suggesting global metabolic dysregulation. Altered ketone body metabolites normalized after therapeutic weight loss. CSF:serum urea ratio was altered, which may influence ICP dynamics and headache. Elevated CSF acetate, known to stimulate trigeminal sensitization, was associated with headache morbidity. These alterations of metabolic pathways specific to IIH provide biological insight and warrant mechanistic evaluation. Registered on ClinicalTrials.gov, NCT02124486 (submitted April 22, 2014) and NCT02017444 (submitted December 16, 2013).

Reaction Model and Mechanism of Preparing (Al2O3 + C) Precursor for Carbothermal Synthesis of AlN by a Modified Low Temperature Combustion Synthesis Method.

The preparation of a homogeneous mixture of (Al2O3 + C) precursor is the key step for the successful synthesis of AlN powders by the carbothermal reduction and nitridation method. In the present work, the homogeneous (Al2O3 + C) precursor prepared by a modified low temperature combustion synthesis (MLCS) method by using aluminum nitrate, glucose, and urea as materials exhibited high reaction activity. Furthermore, in order to absolutely control the MLCS process and continuously improve the properties of (Al2O3 + C) precursor, the reaction model of preparing precursors from various molar ratios of urea to aluminum nitrate (U/Al) was investigated by carrying out thermodynamic calculation and by performing experiments in the present work. The whole process was found to involve various phenomena. First, the type and amount of various generated nitrogen-containing gases (N2, NO, N2O, N2O3, N2O4, and NO2) vary with the change of U/Al during combustion process. Second, under the present experimental condition of ignition temperature, the decomposition reaction of aluminum nitrate is more prone to occur than the combustion reaction of urea. Third, the real reaction system with U/Al = 2.5 reaches the highest combustion temperature which is well consistent with the propellant chemical theory. The occurrence of above phenomena was discussed in detail. Moreover, the reaction mechanism of synthesizing precursor from U/Al = 1 with high reaction activity was investigated by using various techniques such as FTIR, XRD, and DTA.

Анализ эффективности использования восстановителя оксидов азота отработавших газов дизелей

The relevance of the article is due to the need to radically improve the environmental performance of automobile diesels. The most significant gaseous toxic component of spent diesel engines are nitrogen oxides. The mechanisms and models of nitrogen oxides formation in the diesel combustion chamber are considered. The analysis of methods for reducing the emission of nitrogen oxides with diesel exhaust gases has been carried out. The most effective method of their purification from nitrogen oxides is the use of SCR technology, in which an aqueous urea solution is supplied to the diesel exhaust system. At a temperature of about 130 °C, urea decomposes into ammonia and carbon dioxide. Ammonia released from urea reacts with nitrogen oxides of exhaust gases, reducing them to nitrogen. A method for calculating the urea supply to the diesel exhaust system has been developed. Tests of the YAMZ-6566 diesel engine equipped with the SCR system were carried out. With an excess urea ratio of 1.03, the efficiency of the SCR system ranged from 89 to 100 %, depending on the operating mode of the diesel engine.

Intradialytic Protein Ingestion and Exercise do Not Compromise Uremic Toxin Removal Throughout Hemodialysis

Dietary protein and physical activity interventions are increasingly implemented during hemodialysis to support muscle maintenance in patients with end-stage renal disease (ESRD). Although muscle maintenance is important, adequate removal of uremic toxins throughout hemodialysis is the primary concern for patients. It remains to be established whether intradialytic protein ingestion and/or exercise modulate uremic toxin removal during hemodialysis. We recruited 10 patients with ESRD (age: 65±16y, BMI: 24.2±4.8kg/m2) on chronic hemodialysis treatment to participate in this randomized cross-over trial. During hemodialysis, patients were assigned to ingest 40g protein or a nonprotein placebo both at rest (protein [PRO] and placebo [PLA], respectively) and following 30min of exercise (PRO+exercise [EX] and PLA+EX, respectively). Blood and spent dialysate samples were collected throughout hemodialysis to assess reduction ratios and removal of urea, creatinine, phosphate, cystatin C, and indoxyl sulfate. The reduction ratios of urea and indoxyl sulfate were higher during PLA (76±6% and 46±9%, respectively) and PLA+EX interventions (77±5% and 45±10%, respectively) when compared to PRO (72±4% and 40±8%, respectively) and PRO+EX interventions (73±4% and 43±7%, respectively; protein effect: P=.001 and P=.023, respectively; exercise effect: P=.25 and P=.52, respectively). Nonetheless, protein ingestion resulted in greater urea removal (P=.046) during hemodialysis. Reduction ratios and removal of creatinine, phosphate, and cystatin C during hemodialysis did not differ following intradialytic protein ingestion or exercise (protein effect: P>.05; exercise effect: P>.05). Urea, creatinine, and phosphate removal were greater throughout the period with intradialytic exercise during PLA+EX and PRO+EX interventions when compared to the same period during PLA and PRO interventions (exercise effect: P=.034, P=.039, and P=.022, respectively). The removal of uremic toxins is not compromised by protein feeding and/or exercise implementation during hemodialysis in patients with ESRD.

Application of Blended Controlled-Release and Normal Urea with Suitable Maize Varieties to Achieve Integrated Agronomic and Environmental Impact in a High-Yielding Summer Maize System

The use of blended controlled-release urea (CRU) with normal urea has appeared to effectively improve grain yield and nitrogen use efficiency in summer maize systems. Nevertheless, the environmental impacts based on a life cycle assessment (LCA) and the ecosystem economic benefits with different maize varieties and ratios of CRU and urea remain unclear. In our study, a consecutive two-year field experiment was designed in the North China Plain (NCP) using two nitrogen (N) rates (0 and 180 kg N ha−1), four N resources (urea-N, CRU-N:urea-N = 1:2, CRU-N:urea-N = 2:1 and CRU-N), and two maize varieties (ZD958 and YH988) in 2019 and 2020. The results showed that a once-off application of basal fertilizer in N180C2 (CRU-N:urea-N = 2:1) and N180C1 (CRU-N:urea-N = 1:2) achieved high grain yields in ZD958 and YH988 (11.0–13.5 Mg ha−1 and 11.3–13.2 Mg ha−1), respectively. Compared to treatment N180U, treatment N180C2 reduced reactive N losses through N leaching (−34.6%), ammonia volatilization (−17.1%), and nitrous oxide emissions (−42.0%) in variety ZD958, whereas treatment N180C1 reduced reactive N losses through N leaching (−20.3%), ammonia volatilization (−13.2%), and nitrous oxide emission (−24.2%) in variety YH988. The N180C2 and N180C1 treatments achieved the lowest C footprint (267.4 and 267.9 kg CO2 eq Mg−1) for ZD958 and YH988, respectively. Furthermore, N180C2 and N180C1 achieved the highest ecosystem economic benefits for ZD958 and YH988 of 831 and 1101 $ ha−1, respectively. In summary, the application of the mixture of controlled release urea and standard urea at appropriate N rates not only achieved a high grain yield but also enhanced the ecological economic benefits while mitigating the negative environmental impacts. To sum up, using the correct CRU-N management practices coordinated with suitable genetic varieties is an effective way of achieving sustainable and environmentally friendly maize production in a high-yielding summer maize system.

One-step synthesis of polymer based N-doped porous carbon with enriched nitrogen content and its enhanced electrochemical properties in supercapacitors

N-doped porous carbon (N-PC) is considered as a promising candidate for electrochemical energy storage. However, the complicated multistep process is the biggest bottleneck. Here, a facile one-step strategy was employed to fabricate the N-doped porous carbon via the co-pyrolysis of urea and poly(acrylic acid-co-maleic acid) sodium salt (PAMS) without the protection of inert gas at 550 °C. When the mass ratio of urea to PAMS is 4:1, the microstructure and electrochemical properties of the as-prepared sample (N-4PC) are obviously improved compared with that of the direct carbonization of PAMS (PC). N-4PC presents salient peculiarities with much more mesopores, higher specific surface area of 181.5 m2 g−1 far more than PC (23.6 m2 g−1), and its nitrogen content is up to 10.61 at. %. In a three-electrode configuration using 6 M KOH, owing to the synergistic effect of pyridinic N, pyrrolic N and graphitic N atoms, N-4PC shows an outstanding specific capacity of 210 F g−1 far more than that of PC (93 F g−1) at 1 A g−1, and a significant capacity retention rate of 79 % much higher than PC (47 %) at 20 A g−1. Furthermore, the symmetric supercapacitor fabricated by N-4PC delivers an attractive specific capacitance of 140 F g−1 at 1 A g −1, and 4.9 Wh kg−1 energy density when the power density is 265 W kg−1 in 6 M KOH. The equipment achieves superior cycle stability with capacity retention of 97 % after 7000 cycles at 1 A g−1. Additionally, N-4PC also achieves great energy densities of 6.7 Wh kg−1 at the power density of 372.3 W kg−1 in 1 M H2SO4 and 12.5 Wh kg−1 at the power density of 521.5 W kg−1 in 1 M Li2SO4. The fabricated nitrogen-doped porous carbon material has a great potential application prospect in energy storage equipment.

Effects of Controlled Release Urea Formula and Conventional Urea Ratio on Grain Yield and Nitrogen Use Efficiency of Direct-Seeded Rice

A one-off application of bulk blend urea (BBU), which includes a controlled release urea formula and conventional urea, has been recommended to simplify fertilisation management for direct-seeded rice. However, the effects of different basal application ratios of controlled-release urea formula and conventional urea on yield and nitrogen (N) use efficiency remain unknown in direct-seeded rice. This study set up three BBU treatments in which the controlled-release urea formula provided 50% (BBU1), 60% (BBU2), and 70% (BBU3) of the total N. This study measured their effects on grain yield and N use efficiency of direct-seeded rice. Split fertilisation with conventional urea was used as the control (CK). The study concluded four key points: (i) the grain yield of direct-seeded rice decreased as the proportion of controlled-release urea formula increased, (ii) BBU1 increased grain yields by 8.1–8.6% and 10.2–10.6% compared to BBU2 and BBU3, respectively, as well as a greater number of panicles and spikelets per m2, and post-anthesis dry matter accumulation, (iii) the N recovery efficiency and N agronomic efficiency of BBU1 were significantly higher than those of BBU2 and BBU3 treatments, and the nitrogen accumulation was also found to be more, and (iv) compared with the CK, BBU1 achieved considerable grain yield and nitrogen use efficiency while reducing the amount of fertilisation. In conclusion, the appropriate reduction of the basal application ratio of the controlled-release urea formula for direct-seeded rice increased grain yield and nitrogen use efficiency.

Effect of temperature and composition on density and dynamic viscosity of (lanthanide metal salts + urea) deep eutectic solvents

• Lanthanide metal-based type IV deep eutectic solvents (DESs) are prepared. • Density of type IV metal DESs are higher compared to the other urea-based DESs. • Dynamic viscosities of these DESs are lower compared to other urea-based DESs. • Viscosity of the DESs exhibits Vogel − Fulcher − Tammann (VFT) temperature dependence. • Density and viscosity both decrease with increase in mole ratio of urea. Deep eutectic solvents (DESs) are rapidly becoming solvent media of prominence due not only to their unique properties but also to their promising environmentally-benign nature. For effective utilization of these neoteric media, assessment of their physical properties is essential. Density and dynamic viscosity of a class of DESs constituted of a hydrated lanthanide salt and urea at varying composition in the temperature range 293.15 to 363.15 K are presented. Specifically, different possible eutectic mixtures of lanthanum nitrate hexahydrate: urea (named La : Urea), cerium nitrate hexahydrate: urea (named Ce : Urea) and gadolinium nitrate hexahydrate: urea (named Gd : Urea) are investigated. DES (Gd : Urea) at 1: 2 mole ratio exhibits the highest density (1.98783 g.cm −3 at 293.15 K) of all the DESs investigated; density is found to decrease with increasing urea. Density of these DESs decreases linearly with increasing temperature. Dynamic viscosity of these DESs also decrease with increasing urea content. The temperature dependence of the dynamic viscosity follows Vogel − Fulcher − Tammann (VFT) expression. While the activation energy of viscous flow ( E a,η ) for these (lanthanide salt : Urea) DESs is closer to those of (choline chloride + H-bond donor) DESs, their viscosity-temperature dependence is similar to that of common imidazolium ionic liquids.

Development of Fire Retardant on Jute by Chemical Means

Jute is highly flammable in character. Due to its high degree of flammability, the versatile use of this fibre is handicapped to some extent, particularly in some specific purpose where jute products with flame resistance finishes and demanded. Considering this disadvantage, a research project was undertaken to make this fibre flameproof and therefore safer in specialized textile uses. The study was performed using yarn and fabrics which were desized with diastase and lissapol-N. Yarn and fabrics were scoured with sodium carbonate, sodium hydroxide under some standard conditions. These pretreated yarns and fabrics were used in the whole experimental work. The treated yarns were tested for flame retardant by subjecting them to the luminous flame of Bunsen burner and by observing the time of flaming (after flame) and time of glowing (flameless combustion, after glow), if any Percentage losses of strength of the treated yarn and fabrics were also measured by standard method. Different solutions of fire resistant chemicals were prepared to change the chemical, concentration and pH ratio of the solution. Jute fabrics and yarns treated with 65% solution of urea and ammonium dihydrogen phosphate (the ratio of urea and ADP being 3:2) together with 2% Turpex NP and 3-6% perapret PE-40% were found durably flame retardant causing minimum loss of the strength. This research was focused on fire resistant treatment of jute yarn and fabrics with different chemicals to make jute products for diversified textile uses.

Comparison of four medium cut-off dialyzers.

Recently, several pharmaceutical companies have developed new medium cut-off (MCO) dialyzers for expanded hemodialysis (HDx). This study aimed to compare the safety and efficacy of four MCO dialyzers, against each other and versus high-flux hemodialysis (HD) and post-dilution hemodiafiltration (HDF). A prospective study was carried out on 23 patients who underwent six dialysis sessions: two sessions with the FX80 Cordiax in HD and HDF, and four HDx sessions with the Phylther 17-SD, Vie-18X, Elisio HX19 and Theranova 400 dialyzers. The reduction ratios (RRs) of urea, creatinine, β2-microglobulin, myoglobin, kappa free immunoglobulin light chain (κFLC), prolactin, α1-microglobulin, α1-acid glycoprotein, lambda (λFLC) and albumin were compared. Dialysate albumin loss was also measured. The differences in efficacy between the evaluated dialyzers were minimal in small molecules and even up to the size of β2-microglobulin. The main differences were found between myoglobin, κFLC, prolactin, α1-microglobulin and λFLC RRs, in which all four MCO dialyzers, with similar efficacy, were clearly superior to HD and slightly inferior to HDF treatment. Albumin losses in the dialysate with HD dialyzers were <1 g and between 1.5 and 2.5 g in HDx and HDF. The global removal score values were similar in all four HDx treatments, and again significantly higher than those with HD. The results of the four MCO dialyzers evaluated in this study showed good efficiency, with no significant performance differences between them while being completely safe in terms of albumin loss. Likewise, the study confirms the superiority of HDx over high-flux HD with an efficacy close to that of post-dilution HDF.

Secretory phospholipase A2 expression and activity in preterm clinical chorioamnionitis with fetal involvement.

Secretory phospholipase A2 (sPLA2) regulates the first step of inflammatory cascade and is involved in several pathological processes. sPLA2 also plays a role in preterm labor and parturition, since they are triggered by inflammatory mediators such as prostaglandins. Interestingly, chorioamnionitis (i.e., the presence of intrauterine inflammation) is also often associated with preterm birth. We aimed to verify if chorioamnionitis with fetal involvement modifies sPLA2 activity and expression profile in mothers and neonates delivered prematurely. We collected maternal plasma and amniotic fluid, as well as bronchoalveolar lavage fluid from preterm neonates born to mothers with or without clinical chorioamnionitis with fetal involvement. We measured concentrations of sPLA2 subtype-IIA and -IB, total enzyme activity, and proteins. Urea ratio was used to obtain epithelial lining fluid concentrations. Enzyme activity measured in maternal plasma (P < 0.001) and amniotic fluid (P < 0.001) was higher in chorioamnionitis cases than in controls. This was mainly due to the increased production of sPLA2-IIA, as the subtype -IB was present in a smaller amount and was similar between the two groups; sPLA2-IIA was increased in epithelial lining fluid (P = 0.045) or increased, although without statistical significance, in maternal plasma (P = 0.06) and amniotic fluid (P = 0.08) of chorioamnionitis cases. Cytokines that are known to increase sPLA2-IIA expression (TNF-α and IL-1β) or whose expression was increased by sPLA2-IIA (IL-8) were higher in histologically confirmed chorioamnionitis [TNF-α (P = 0.028), IL-1β (P < 0.001), and IL-8 (P = 0.038)]. These data represent the basis for future studies on sPLA2-IIA inhibition to prevent deleterious consequences of chorioamnionitis and preterm birth.

Network Analysis Reveals the Combination of Controlled-Release and Regular Urea Enhances Microbial Interactions and Improves Maize Yields.

Increased complexity of microbial networks can contribute to increased biodiversity and multifunctionality and thus crop productivity. However, it is not clear which combination ratio of regular and controlled-release urea will increase the soil microbial community complexity and improve maize yield in the North China Plain. To address this knowledge gap, a 2-year field experiment was conducted to explore the effects of the combination of regular (U) and controlled release (S) urea ratios [no fertilizer control (CT), regular urea alone (U), controlled-release urea alone (S), controlled-release urea mixed with regular urea 3:7 (SU3), controlled-release urea mixed with regular urea 5:5 (SU5), and controlled-release urea mixed with regular urea 7:3 (SU7)] on XianYu 688 yield and its rhizosphere and bulk soil microbial community composition and network complexity at different fertility stages. The combination of controlled-release and regular urea increased the N agronomic efficiency, N partial factors productivity, maize yield, and grain number per spike, with the maximum maize yield (9,186 kg ha–1) being achieved when the ratio of controlled-release urea to regular urea was 3:7 (SU3, p < 0.05). Maize yield increased by 13% in the SU3 treatment compared to the CT treatment. Rhizosphere soil microbial diversity remained stable at the silking stage of maize while increased at the physiological maturity stage of maize, with the increasing controlled-release to regular N fertilizer ratios (from 3:7 to 7:3, p < 0.05). This result suggests that a combination of regular and controlled-release N fertilizer can still substantially increase soil microbial diversity in the later stages of maize growth. The combination of controlled-release and regular urea is more effective in improving microbial network total links and average degree, and N agronomic efficiency (R2 = 0.79, p < 0.01), N partial factor productivity (R2 = 0.79, p < 0.01), spikes per unit area (R2 = 0.54, p < 0.05), and maize yield (R2 = 0.42, p < 0.05) increased with the microbial network complexity. This result indicates that the higher microbial network complexity is strongly associated with the higher N agronomic efficiency and N partial factors productivity and maize yield. In conclusion, the ratio of controlled-release to regular urea at SU3 not only increases the yield of maize and N agronomic efficiency but also enhances microbial diversity and network complexity in the North China Plain.

Removal of organic contaminants by starch-derived porous carbon via peroxymonosulfate activation: The role of N doping and Fe/Mn loading

In this work, Fe/Mn-loaded nitrogen-doped porous carbonaceous materials were synthesized by a one-step pyrolysis process for organic contaminants removal. The effects of the component ratios of starch, urea, sodium bicarbonate, iron and manganese salts and pyrolysis temperatures on the removal performance of bisphenol A (BPA) were discussed. FeMn@CN-800, which pyrolyzed at 800 °C with a mass ratio of starch∶urea∶Fe∶Mn = 100∶100∶0.34∶0.66 showed 95.4% BPA removal and 73.5% mineralization within 60 min. Large specific surface (663 m2 g−1), rich hierarchical pore structures and N-doping facilitated the adsorption of BPA and peroxymonosulfate (PMS). Fe and Mn are located in the carbon layer in the form of iron carbide and manganese oxide, and act as electron donors to activate the PMS. Chemical quenching tests and electron paramagnetic resonance (EPR) confirmed that hydroxyl radicals (•OH), sulfate radicals (SO4•‐), superoxide anion radical (O2•‐), and singlet oxygen (1O2) are the ROS in this system. Electrochemical tests showed the formation of catalyst-PMS complexes and catalyst facilitated the direct electron transfer from BPA to PMS. The effect of reaction parameters, cyclic experiments, possible BPA degradation pathways were investigated. This work provides the first systematic evaluation of starch-derived materials as high-performance catalysts for PMS-based advanced oxidation processes.

Fractionation of fatty acid methyl esters via urea inclusion and its application to improve the low-temperature performance of biodiesel

Biodiesel is viewed as the alternative to petroleum diesel, but its poor low-temperature performance constrains its utilization. Cloud point (CP), the onset temperature of thermal crystallization, appropriately shows the low-temperature performance. The effective way to reduce CP is to remove saturated fatty acid methyl esters (FAMEs). Compared to current methods, this work describes an extraordinary approach to fractionating FAMEs by forming solid urea inclusion compounds (UICs). Urea inclusion fractionation reduces the CPs by removing high melting-point linear saturated FAME components. Urea inclusion fractionation in this study was performed under various processing conditions: mass ratios of urea to FAMEs and solvents to FAMEs, various solvents, FAMEs from various feedstocks, and processing temperatures. Supersaturation of urea in the solution is the driving force, and it significantly affects yield, composition, CP, separation efficiency, and selectivity. Through a single urea inclusion fractionation process, FAMEs, except palm oil FAMEs, resulted in CP reduction ranging from 20 to 42 oC with a yield of 77–80% depending on the compositions. CP of palm oil FAMEs could reach as low as -17 oC with a yield of 46% after twice urea inclusion fractionation. According to the model prediction, the cetane number after urea inclusion fractionation decreased about 0.7–2 but was still higher than the minimum biodiesel requirement. Oxidation stability after urea inclusion decreased according to the proposed model, but this can be mitigated by adding antioxidants. Emission evaluation after urea inclusion fractionation indicated decreased hydrocarbons, carbon monoxide, and particulate matter. However, it resulted in the increasing emission of nitrogen oxides.

Ce–Zr-Sm ternary oxides synthesized via a template free urea-hydrothermal method

Nano-crystalline Ce0.9Zr0.1-xSmxO2-δ (0 ≤ x ≤ 0.10) mixed oxides were synthesized for the first time by a urea-hydrothermal method without the use of template or structure directing agents. The use of a high molar ratio of urea to metal cations and temperature reaction ensures the formation of a single-phase homogeneous ternary solid solution. The (NH4)2Ce(NO3)6 precursor, in a greater proportion, together with urea acts as a structure directing agent towards the completion of a self-assembly shuttle to dumbbells to sphere sequence. The analysis of the obtained morphologies has demonstrated that the physicochemical nature of the doping precursor in solution has a strong influence on the final morphology without losing morphological control. Thus, the ZrO(NO3)2 precursor favors the formation of cauliflower-type particles whereas Sm(NO3)3 favors the formation of spheres. As a result, the morphology of the samples evolves from cauliflowers to spheres as Sm content increases in the mixed oxides, with a great effect on the high specific surface area (80–115 m2.g−1) and total pore volume (0.109–0.315 cm3.g−1) obtained in all cases. Solids reduce in three stages reaching high reduction percentages (≈50%).

Aluminum nitride nanoparticles with high purity prepared via urea glass route under different sintering conditions

Aluminum nitride (AlN) ceramic is widely used in lots of fields, but its high-efficiency preparation still needs to be developed. In this paper, AlN nanoparticles are prepared from urea and aluminum chloride hydrate by a facile urea glass route in NH3 atmosphere. The products are characterized by X-ray powder diffraction, laser particle size analyzer, scanning electron microscope and transmission electron microscope. The results show that the urea content present less effects on the crystal phase of the AlN ceramic powder. Hexagonal aluminum nitride (h-AlN) nanoparticles with high purity can be obtained when the heat treatment temperature is above 900 °C. The crystallite size of AlN nanoparticles is enlarged with increasing temperature. The optimized molar ratio of urea to aluminum salt is 6 and the sintering temperature is 1000 °C. The average crystallite size of this product is 17.0 nm and the average particle size (D50) is 159.5 nm. The element distributions of N and Al in the AlN nanoparticles are highly coincident, which means that N and Al atoms in ceramic nanoparticles are well combined.

Efficacy and Safety of the Medium Cut-Off Elisio HX Dialyzer

Introduction: The medium cut-off Elisio HX dialyzer by Nipro became commercially available in Europe in 2021, but there are still no reports of in vivo data. This study aimed to evaluate the safety and efficacy of it compared with previously evaluated hemodialysis (HD), expanded HD (HDx), and postdilution hemodiafiltration (HDF) treatments. Methods: A prospective study was carried out on 18 patients who underwent 5 dialysis sessions: FX80 Cordiax in HD, Elisio H19 in HD, Elisio HX19 in HDx, Theranova 400 in HDx, and FX80 Cordiax in HDF. The reduction ratios of urea, creatinine, ß₂-microglobulin, myoglobin, kappa FLC, prolactin, α₁-microglobulin, α₁-acid glycoprotein, lambda FLC, and albumin were compared. Dialysate albumin loss was measured. Results: The comparison between the different dialysis modalities revealed no difference for small molecules, but HDx and HDF were significantly more efficient than HD for medium and large molecule removal. The efficacy of Elisio HX19 dialyzer in HDx was similar to the Theranova 400, superior to both dialyzers in HD, and slightly lower than HDF. Albumin losses in dialysate with HD dialyzers were less than 1 g, but between 1.5 and 2.5 g in HDx and HDF. The global removal score (GRS) values with HDx treatments were statistically significantly higher than those with HD. The highest GRS was obtained with the helixone dialyzer in HDF. Conclusions: The new MCO dialyzer, Elisio HX, performs with excellent behavior and tolerance. It represents an upgrade compared to their predecessor and is very close to the removal capacity of HDF treatment.

MO422: Strong Positive Association Between GFR and the Urine-To-Plasma Urea Concentration Ratio in Patients With Sickle Cell Disease. Possible Functional Meaning

Abstract BACKGROUND AND AIMS Sickle cell disease (SCD) induces a decline in urine concentration and progressive deterioration of kidney (K) function. Hyperfiltration is often observed before this decline, and plasma urea is low. Oral urea or hydroxyurea improves the condition of these patients (pts). These observations draw the attention to renal urea handling in SCD. Studies suggest that addition of urea into the loop of Henle may indirectly modify NaCl concentration at the macula densa and induce a rise in glomerular filtration rate (GFR) by depressing the tubule-glomerular feedback (TGF) [1]. The urine-to-plasma urea concentration ratio (U/P urea) is a novel marker associated with GFR and the progression of disease in ADPKD [2]. The present study addresses the relationship of U/P urea with GFR in SCD pts. METHOD A total of 184 homozygous SCD pts referred to our department were included. They underwent extensive evaluation including measured GFR (mGFR) (51Cr EDTA clearance) and plasma and 24-h urine chemistries. The association between mGFR and U/P urea was tested using univariate, and multivariate stepwise regression analyses. RESULTS Mean age was 35.6 ± 2.8 years (mean ± SD) and body mass index (BMI) 22.2 ± 0.3 kg/m2. Mean mGFR was 107 ± 3 ml/min x 1.73m2. Hyperfiltration was observed in 37% of pts. Urine volume (UV) 1.71 ± 0.75 L/24h. Urea excretion 267 ± 151 mmol/24h. In 13% of pts fractional excretion of urea (FEurea) exceeded 50%. U/P urea (42 ± 20) varied from 6 to 112. It was not associated with 24-h urea excretion but showed a negative association with UV (P &amp;lt; 0.007). mGFR was strongly and positively associated with U/P urea (r = 0.58, P &amp;lt; 0.0001) but not with U/P osmolarity (see Figure and Table). mGFR was also associated with U/P creatinine although more weakly (r = 0.266, p &amp;lt; 0.0001) and with BMI and negatively associated with age, MAP and serum creatinine (creat). After adjustment for U/P creat, the association between mGFR and U/P urea remained highly significant, whereas, after adjustment for U/P urea, the association between mGFR and U/P creat disappeared. In multivariate regression, mGFR remained strongly associated with U/P urea. CONCLUSION Our data show a strong association between mGFR and U/P urea that remains highly significant after multivariate analysis. i) This suggests that a specific estimated GFR equation for SCD patients including the U/P urea ratio could be clinically more relevant than CKD-EPI equations. ii) A specific mechanism may link GFR and intrarenal urea handling, as U/P urea but not U/P osmolarity appears to be involved. Urea could play a role, indirectly, in the regulation of GFR [1]. In SCD, the longer transit time of the blood in vasa recta may favour countercurrent exchanges and lead to a greater addition of urea in loops of Henle (increasing the U/P urea ratio) and thus increasing GFR by reducing TGF. Sickled red cells and resulting in slower blood flow in the medulla may selectively influence urea handling, participating in high FEurea and GFR often observed in SCD pts. iii) As is the case in ADPKD, more attention should be given to longitudinal studies to the relationship between U/P urea and kidney disease progression in SCD pts.

Composition manipulation of heat-resistant iron-based cores@graphitic carbon@amorphous carbon derived from urea-modulated MOFs for high-efficient microwave absorption

Designing multifunctional microwave absorption materials is crucial in practical application. Herein, the iron-based cores@graphitic carbon@amorphous carbon composites with diverse phase compositions were annealed from urea-modulated metal organic frameworks (MOFs), MIL-88A, as precursors. By simply varying the mass ratio of urea and MIL-88A, the chemical compositions of as-prepared samples were well adjusted, which brought the variation of interfacial polarization, dipole polarization, and magnetic response. Meanwhile, the structure with outer-layered amorphous carbon and inner-layered graphitic carbon enhanced impedance matching. Therefore, with stronger microwave attenuation brought by polarization loss and better impedance matching, the high-efficient microwave absorption performance with a minimum reflection loss (RL) of −67.81 dB at 12.5 GHz and an effective absorption bandwidth of 5.76 GHz was obtained with S-05 (Fe/Fe3C/Fe15.1C@graphitic carbon@amorphous carbon), which was prepared with the weight ratio of MIL-88A and urea at 2:1. Meanwhile, the iron-based cores@graphitic carbon@amorphous carbon composites possess good heat-resistant properties due to the existence of protecting carbon layers. Thus, urea-assisted treatment paves a way for acquiring multifunctional absorbers derived from MOFs with enhanced microwave absorption performance.