Ratio Of Urea Research Articles

The characterizations of nanofluid type urea formaldehyde resins

For reducing the emission of formaldehyde, urea formaldehyde (UF) resin adhesives used in the wood-based panel industry are mainly synthesized by adding urea in stages to reduce the molar ratio of formaldehyde and urea. Although the lower molar ratio UF resin has lower formaldehyde emissions, it also has the defects of longer curing time and lower bonding strength when being used in wood-based panel products. In this study, nanofluid type UF resins adhesives were prepared by dispersing SiO2 and TiO2 nanoparticles with six concentrations levels, 0%, 0.2%, 0.4%, 0.6%, 0.8% and 1% into UF resins with 1.0 and 1.3 M ratio by the assistance of ultrasound, respectively. It was found that the excellent thermal conductivity of the nanofluid type adhesives could eliminate the defects of the low molar ratio UF resins. When nano-SiO2 and nano-TiO2 were incorporated, the viscosity increased as the nanoparticles concentration increased, the maximum viscosity increased by 11.7% (1.0UF) and 15.0% (1.3UF) with nano-SiO2, the free formaldehyde content, curing time, and pot life of UF resins declined in varying degrees with nanoparticles loading level increased, the maximum amount of free formaldehyde content reduced by 41.2% (1.0UF) and 43.9% (1.3UF) with nano-TiO2, the maximum reduction of curing time was 25.80% (1.0UF) and 42.6% (1.3UF) with nano-TiO2, the pot life maximum decreased by 39.7% (1.0UF) and 43.0% (1.3UF) with nano-SiO2. Nanofluid type UF resins had much higher bonding strength with lower formaldehyde emission than pristine UF resins after being treated with same hot-pressing in plywood manufacture. The maximum of bonding strength increased by 28.1% (1.0UF) and 28.8% (1.3UF) with nano-SiO2, and the maximum amount of formaldehyde emissions reduced by 48.7% (1.0UF) with nano-SiO2 and 41.9% (1.3UF) with nano-TiO2. Meanwhile, the results showed that nanofluid type UF resin used in plywood manufacture exhibited the ability to decrease the hot-pressing temperature or shorten the hot-pressing time.

Fabrication of N-doped micro-mesoporous carbons from industrial alkali lignin with urea assistance for high-efficiency adsorption of methylene blue

N-doping is a prospective strategy to improve the adsorption efficiency of adsorbents. Herein, N-doped porous carbons (PCs) were synthesized from industrial alkali lignin (IAL) with urea assistance for adsorbing methylene blue (MB). The nitrogen content and pore structure could be adjusted by changing urea dosage. The PCs were characterized via scanning electron microscopy (SEM), N2 adsorption-desorption experiments, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and Zeta potential. The optimized weight ratio of urea to IAL was 1:1. NLC-1 synthesized under this condition possessed high micropore volumes (Vmicro) and mesopore volumes (Vmeso), namely 0.3531 and 0.3480 cm3/g, respectively, and the specific surface area (SSA) of NLC-1 reached 1131 m2/g. The adsorption capacities of PCs for MB were compared and discussed. Notably, the as-obtained NLC-1 exhibited the highest adsorption capacity of 785.8 mg/g. This was attributed to the pore filling and the appropriate N content (3.780%). The adsorbing process of MB onto NLC-1 was well reproduced by the Langmuir model. Furthermore, the kinetic data conformed to the pseudo-second-order (PSO) model, and the MB adsorption process was spontaneous according to the thermodynamic parameters. Overall, this study indicates that PCs from IAL have a great potential for MB adsorption.

The urine-to-plasma urea concentration ratio is associated with eGFR and eGFR decline over time in a population cohort.

Evaluation of renal function and of factors associated with its decline are important public health issues. Besides markers of glomerular function [e.g. glomerular filtration rate (GFR)], those of tubular functions are rarely evaluated. Urea, the most abundant urinary solute, is markedly concentrated in urine when compared with plasma. We explored the urine-to-plasma ratio of urea concentrations (U/P urea ratio) as a marker of tubular functions. We evaluated the relationship of the U/P urea ratio with eGFR at baseline in 1043 participants (48±17 years) from the Swiss Kidney Project on Genes in Hypertension (SKIPOGH) population-based cohort, using mixed regression. In 898 participants, we assessed the relation between U/P urea ratio and renal function decline between two study waves 3 years apart. We studied U/P ratios for osmolarity, Na, K and uric acid for comparison. In a transversal study at baseline, estimated GFR (eGFR) was positively associated with U/P-urea ratio [βscaled=0.08, 95% CI (0.04; 0.13)] but not with the U/P ratio of osmolarity. Considering separately participants with renal function >90 or ≤90mL/min × 1.73 m2, this association was observed only in those with reduced renal function. In the longitudinal study, eGFR declined at a mean rate of 1.2mL/min per year. A significant association was observed between baseline U/P urea ratio and eGFR decline [βscaled=0.08, 95% CI (0.01; 0.15)]. A lower baseline U/P urea ratio was associated with a greater eGFR decline. This study provides evidence that the U/P urea ratio is an early marker of kidney function decline in the general adult population. Urea is easy to measure with well-standardized techniques and at low cost. Thus, the U/P urea ratio could become an easily available tubular marker for evaluating renal function decline.

Urea intercalated halloysite/sodium alginate composite hydrogels for slow-release fertilizers

The application of nanotechnology in the field of agrochemicals release is an effective way to reduce the use of fertilizers and improve their utilization. Here, different ratios of urea were successfully intercalated into halloysite (Hal) by solid-phase milling method, and the maximum loading of urea was calculated as 14.99 ± 1.33 wt%. X-ray powder diffraction (XRD) demonstrated the distance of the Hal (001) plane increased from 0.7 to 1.0 nm by the urea intercalation. Subsequently, urea-Hal‑sodium alginate (SA) hydrogel beads (UHS) were fabricated by Ca2+ crosslinking method. SA and Hal content has a significant influence on the morphology and surface properties of the hydrogel. The optimal ratio of UHS was found as 2 wt% CaCl2, 2 wt% SA, and 2 wt% Hal. UHS had good water retention and slow release properties, and the water retention rate of UHS was increased by 13% compared with that of raw soil. The release curve showed that the release time of urea in UHS was 60 times longer compared to pure urea. Furthermore, using wheat as a plant model, UHS can provide slow-release nitrogen nutrients to promote the growth of wheat. In virtue of good swelling and slow-release properties, low cost, simple preparation process and environmental friendliness, UHS has a promising future in slow-release fertilizers for modern agriculture technology.

Tailor-made starch-based adhesives chemically modified with NaOH:urea and their applications on a cellulosic substrate

Adhesives formulated with native starches have high viscosity, low solids content, poor bond strength and stability due to the starch retrogradation. To overcome this problem, a strategy is the starch treatment with NaOH solution combined with urea, capable of intercalating in the polymeric chains of starch. The aims of this work were to develop adhesives based on chemically modified cassava starch with different NaOH:urea ratios and to study in depth the effect induced by the addition of different concentrations of alkali and urea in the adhesive capacity of formulations that determine their subsequent application in paper-based packaging.Firmness and consistency of the adhesive increased for the 1:1 ratio while it decreased for the NaOH:urea 2:1 ratio, suggesting that the hydrolysis of polymer chains occurred. Additionally, adhesives prepared with 15 % starch maintaining NaOH:urea ratios of 0.5:1: and 1:1 exhibited the highest stress values. ATR-FTIR studies supported the results obtained.It was possible to obtain formulations with different adhesive properties with applications in paper-based packaging. From the analysis of the studied parameters, the combination of 15 % w/w cassava starch with a ratio of NaOH:urea 1:1 allows obtaining adhesives with adequate consistency and adhesive capacity which remain stable during the adhesive storage.

Preparation and Application of a Natural Microspheric Soil Conditioner Based on Gelatin, Sodium Alginate, and Zeolite

In this work, a type of natural microspheric soil conditioner, PZ(Fe)/GL-SA-Urea, was prepared by emulsion cross-linking and sharp-hole coagulation bath methods. Gelatin (GL) and sodium alginate (SA) were selected as the outermost shell, and the prepared FeOOH was loaded on pickling zeolite (PZ) to improve the loading ratio of urea. The embedding performance and sustained release behavior of the microspheres showed that when the concentration of urea was 1.5%, the embedding rate reached 37.63%, and the cumulative release rate reached 68% within 100 h, indicating that the microsphere had good encapsulation and sustained release abilities. In addition, the water retention and swelling behaviors of the microspheres can be obtained by controlling the content of added GL. Furthermore, antibacterial and planting experiments revealed that the microspheres had excellent antibacterial effects and can effectively improve soil quality and promote crop growth. Therefore, the PZ(Fe)/GL-SA-Urea microsphere soil conditioners possess good application properties and provide fresh solutions to improve soil quality and raise crop yields.

Removal of Middle Molecules and Dialytic Albumin Loss: A Cross-over Study of Medium Cutoff and High-Flux Membranes with Hemodialysis and Hemodiafiltration.

Key Points HDF and MCO have shown greater clearance of middle-size uremic solutes in comparison with HF dialyzers; MCO has never been studied in HDF.MCO in HDF does not increase the clearance of B2M and results in a higher loss of albumin. Background Middle molecule removal and albumin loss have been studied in medium cutoff (MCO) membranes on hemodialysis (HD). It is unknown whether hemodiafiltration (HDF) with MCO membranes provides additional benefit. We aimed to compare the removal of small solutes and β2-microglobulin (B2M), albumin, and total proteins between MCO and high-flux (HFX) membranes with both HD and HDF, respectively. Methods The cross-over study comprised 4 weeks, one each with postdilutional HDF using HFX (HFX-HDF), MCO (MCO-HDF), HD with HFX (HFX-HD), and MCO (MCO-HD). MCO and HFX differ with respect to several characteristics, including membrane composition, pore size distribution, and surface area (HFX, 2.5 m2; MCO, 1.7 m2). There were two study treatments per week, one after the long interdialytic interval and another midweek. Reduction ratios of vitamin B12, B2M, phosphate, uric acid, and urea corrected for hemoconcentration were computed. Dialysis albumin and total protein loss during the treatment were quantified from dialysate samples. Results Twelve anuric patients were studied (six female patients; 44±19 years; dialysis vintage 35.2±28 months). The blood flow was 369±23 ml/min, dialysate flow was 495±61 ml/min, and ultrafiltration volume was 2.8±0.74 L. No significant differences were found regarding the removal of B2M, vitamin B12, and water-soluble solutes between dialytic modalities and dialyzers. Albumin and total protein loss were significantly higher in MCO groups than HFX groups when compared with the same modality. HDF groups had significantly higher albumin and total protein loss than HD groups when compared with the same dialyzer. MCO-HDF showed the highest protein loss among all groups. Conclusions MCO-HD is not superior to HFX-HD and HFX-HDF for both middle molecule and water-soluble solute removal. Protein loss was more pronounced with MCO when compared with HFX on both HD and HDF modalities. MCO-HDF has no additional benefits regarding better removal of B2M but resulted in greater protein loss than MCO-HD.

Hydrolytic and thermal stability of urea‐formaldehyde resins based on tannin and betaine bio‐fillers

AbstractIn this work, betaine (trimethyl glycine) and tannin (complex biomolecules of polyphenolic nature) were used as bio‐fillers. Urea‐formaldehyde (UF) resin with a molar ratio of formaldehyde versus urea (FA/U) of 0.8 was synthesized in situ with tannin and betaine as bio‐fillers, to obtain UF resin with reduced free FA content and increased hydrolytic and thermal stability by the principles of sustainability. The samples TUF (with tannin) and BUF (with betaine) were characterized by using X‐ray diffraction analysis (XRD), non‐isothermal thermogravimetric analysis (TGA), and differential thermal analysis (DTA), supported by data from Fourier Transform Infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The percentage of free FA in modified BUF resin is 0.1%, while the percentage of free FA in tannin‐modified resin is 0.8%. The hydrolytic stability of the modified UF resins was determined by measuring the concentration of liberated FA in the modified UF resins, after acid hydrolysis. The modified BUF resin is hydrolytically more stable because the content of released FA is 3.6% compared to the modified TUF resin, where it was 7.4%. Based on the value for T5%, the more thermally stable resin is the modified TUF resin (T5% = 123.1°C), while the value of the T5% for the BUF resin is 83.1°C. This work showed how UF bio‐composite with reduced free FA content and increased hydrolytic and thermal stability can be obtained using tannin and betaine as bio‐fillers.

High-Strength, High-Water-Retention Hemicellulose-Based Hydrogel and Its Application in Urea Slow Release.

The use of fertilizer is closely related to crop growth and environmental protection in agricultural production. It is of great significance to develop environmentally friendly and biodegradable bio-based slow-release fertilizers. In this work, porous hemicellulose-based hydrogels were created, which had excellent mechanical properties, water retention properties (the water retention ratio in soil was 93.8% after 5 d), antioxidant properties (76.76%), and UV resistance (92.2%). This improves the efficiency and potential of its application in soil. In addition, electrostatic interaction and coating with sodium alginate produced a stable core-shell structure. The slow release of urea was realized. The cumulative release ratio of urea after 12 h was 27.42% and 11.38%, and the release kinetic constants were 0.0973 and 0.0288, in aqueous solution and soil, respectively. The sustained release results demonstrated that urea diffusion in aqueous solution followed the Korsmeyer-Peppas model, indicating the Fick diffusion mechanism, whereas diffusion in soil adhered to the Higuchi model. The outcomes show that urea release ratio may be successfully slowed down by hemicellulose hydrogels with high water retention ability. This provides a new method for the application of lignocellulosic biomass in agricultural slow-release fertilizer.

Deep Eutectic Solvents for Efficient Drug Solvation: Optimizing Composition and Ratio for Solubility of β-Cyclodextrin.

Deep eutectic solvents (DESs) show promise in pharmaceutical applications, most prominently as excellent solubilizers. Yet, because DES are complex multi-component mixtures, it is challenging to dissect the contribution of each component to solvation. Moreover, deviations from the eutectic concentration lead to phase separation of the DES, making it impractical to vary the ratios of components to potentially improve solvation. Water addition alleviates this limitation as it significantly decreases the melting temperature and stabilizes the DES single-phase region. Here, we follow the solubility of β-cyclodextrin (β-CD) in DES formed by the eutectic 2:1 mole ratio of urea and choline chloride (CC). Upon water addition to DES, we find that at almost all hydration levels, the highest β-CD solubility is achieved at DES compositions that are shifted from the 2:1 ratio. At higher urea to CC ratios, due to the limited solubility of urea, the optimum composition allowing the highest β-CD solubility is reached at the DES solubility limit. For mixtures with higher CC concentration, the composition allowing optimal solvation varies with hydration. For example, β-CD solubility at 40 wt% water is enhanced by a factor of 1.5 for a 1:2 urea to CC mole ratio compared with the 2:1 eutectic ratio. We further develop a methodology allowing us to link the preferential accumulation of urea and CC in the vicinity of β-CD to its increased solubility. The methodology we present here allows a dissection of solute interactions with DES components that is crucial for rationally developing improved drug and excipient formulations.

Tailoring the transesterification activity of MgO/oxidized g-C3N4 nanocatalyst for conversion of waste cooking oil into biodiesel

As a prospective heterogeneous catalyst for transesterification, magnesium oxide (MgO) has long been regarded as a possible candidate. Pure MgO, on the other hand, has a narrow range of applications because of its small surface area and short catalytic lifetime. To overcome these problems, in this work, graphitic carbon nitride (g-C3N4) with higher oxygen doping levels was applied to construct a noteworthy, persistent, and carbon-modified MgO catalyst. The molar ratios of urea to melamine and the mass ratios of oxidized g-C3N4 to MgO in the preparation step are two effective parameters, which were optimized with the Response Surface Methodology (RSM). The significant increase in oil conversion was attained by incorporating O@g-C3N4 nanoparticles composed of urea to melamine at a molar ratio of 2:1 in MgO at a mass percentage of 16.7. O@g-C3N4 had an outstanding effect on the immobilization of oxygen-rich functional groups on the MgO-based catalyst and an increase in the surface area. Also, the effects of transesterification parameters and their interactions on oil conversion were explored using the RSM, and then reusability tests were carried out using the fine-tuned parameters. The prepared catalysts were characterized using a variety of methods, including Field-Emission Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (FESEM-EDS), Fourier Transform Infrared (FTIR) spectroscopy, Temperature Programmed Desorption of CO2 (CO2-TPD), Brunauer-Emmett-Teller (BET) analysis, and powder X-Ray diffraction, in order to determine their basicity, morphology, and composition. The optimum biodiesel yield of 98.80% was attained at 99.6 °C for 133 min with a catalyst quantity of 5.9 wt% and a methanol to oil molar ratio of 14.6. The stability and lifespan of the as-optimized catalyst (OCN2MgO(0.2)) were confirmed over four consecutive cycles. It can be concluded that this solid catalyst could be used to convert low-cost waste cooking oil into biodiesel in a single step.

One-step fabrication of mesoporous maghemite nanoparticles by autoignition: Effect of fuel ratio on crystalline structure, magnetic characteristics and textural properties

The effect of urea ratio on crystalline structure, magnetic characteristics, and textural properties of maghemite nanoparticles produced through the autoignition was evaluated in the current investigation. In order to achieve mesoporous nanoparticles with average pore diameter of 14 nm, the fuel ratio should be fixed at the level of 3.0. Autoignition favors for the fabrication of relatively pure maghemite nanoparticles with the saturation magnetization of 52 emu g−1, if the fuel ratio is adjusted at the level of 5.0. The mesopores with mean size of 33 nm were distributed within the nanoparticles, providing a surface area of 18.3 m2 g−1.

Alkylaluminum/Urea Hybrid Cocatalysts and Their Use in Iron‐Catalyzed Oligomerization of Ethylene

AbstractThe bis(imino)pyridyl iron‐based ethylene oligomerization catalysts have the advantages of mild reaction conditions, high activity and high selectivity to linear α‐olefins. However, barriers, such as high polymer content in the product mixture and large methylaluminoxane (MAO) dosage, are still limitations for the development of these systems at the industrial scale. In this study, new cocatalysts are prepared by the reaction of alkylaluminums with urea and its derivatives, and successfully used to activate iron‐based catalysts. It is found that the type and molar ratio of alkylaluminum and urea have significant influence on the performance of the cocatalysts. The activity of the preferred triisobutylaluminum/urea activated systems reaches more than 3.0 × 108 g (mol‐Fe)−1 h−1, and the polymer content can be controlled to be less than 2 wt.%. Notably, the catalytic system exhibits good high temperature stability, the activity can still reach 1.0 × 108 g (mol‐Fe)−1 h−1 even at 120 °C. Further 1H NMR studies show that alkylaluminum can react with the NH moieties of urea, forming complex alkylaluminum clusters, even aluminoxane‐like structures. This study offers a promising family of cocatalysts, making it possible to simultaneously improve their performance and reduce their cost.

Preparation of Aloe-Emodin Microcapsules and Its Effect on Antibacterial and Optical Properties of Water-Based Coating

With the development of science and technology, the function of waterborne coatings has been advanced to a higher standard, which requires researchers to innovate and expand the research on them. Aloe-emodin is a natural material with antibacterial properties. Applying its antibacterial effect to the coating can enrich its function and meet the diversified needs of consumers. In this study, the urea-formaldehyde resin was used as the wall material and the aloe-emodin as the core material to prepare the microcapsules. The coating rate, yield, and morphology of the microcapsules were characterized. Through an orthogonal experiment and a single factor experiment, the optimization scheme of microcapsule preparation was explored. The results indicated that the optimum preparation process of aloe-emodin microcapsules was as follows: the mass ratio of core material to wall material was 1:15, the molar ratio of urea to formaldehyde was 1:1.2, the temperature of microencapsulation was 50 °C, and the stirring speed of microencapsulation was 600 rpm. On this basis, the aloe-emodin microcapsules with 0%, 1.0%, 3.0%, 6.0%, 9.0%, and 12.0% contents were added to the waterborne coating to prepare the paint films, and their influence on the antibacterial and optical properties of the waterborne paint films was explored. The results demonstrated that the aloe-emodin microcapsules had antibacterial activity. When the content was 6.0%, the comprehensive performance of the film was better. The antibacterial rate of the film against Escherichia coli was 68.1%, and against Staphylococcus aureus it was 60.7%. The color difference of the film was 59.93, and the glossiness at 60° was 7.8%. In this study, the microcapsules that can improve the antibacterial performance of water-based coatings were prepared, which can expand the application of water-based coatings and provide a reference for the study of the functionalization of water-based coatings.

Impact of biochar-based slow-release N-fertilizers on maize growth and nitrogen recovery efficiency.

Biochar has been used to address several environmental problems and may be efficacious as a carrier of N-fertilizer in slow-release N-fertilizer (SRF) formulations. Our objective was to compare the efficacy of SRF pellets formulated with different mass ratios of biochar and urea with traditional N-fertilizers for improving N use efficiency by maize (Zea mays L.) grown under greenhouse conditions. Two different soil types, four SRF formulations with different biochar-to-urea (BCN) ratios (1:2 BCN, 1:3 BCN, 1:4 BCN, and 1:6 BCN), three traditional N-fertilizers (urea, urea ammonium nitrate, and S-coated urea), and unfertilized controls for each soil were tested. The accelerated urea release test showed significantly less loss of urea for the SRF over time than the traditional N-fertilizers. The biochar-based SRF formulations significantly (p<0.05) decreased nitrate leaching loss for both soils relative to the traditional fertilizers. All the SRF formulations increased maize shoot (1%-34%) and root (0%-23%) biomass, N-recovery efficiency (17%-50%), and soil potential mineralizable-N relative to urea and S-coated urea. The results also indicate that the BCN ratio in the SRF formulation can be used to influence the timing of N release and plant N uptake. The results of the greenhouse study suggest that biochar-based SRFs have potential agronomic and environmental benefits; however, more research is needed to assess their agronomic value under field conditions.

Effect of Urea as a Shape-Controlling Agent on the Properties of Bismuth Oxybromides

Bismuth oxybromides were prepared via a solvothermal method by applying different urea amounts during synthesis. The effects of the urea ratio on the morpho–structural properties and photocatalytic activity of the samples were investigated. X-ray diffraction, diffuse reflectance spectroscopy, infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and surface tension measurements were carried out to characterize the samples. Their photoactivity was evaluated by the photocatalytic degradation of rhodamine B and ibuprofen under UV and visible light irradiations. The urea ratio notably influenced morphology, particle size distribution, and photoactivity. However, it only had a limited effect on the crystalline composition, primary crystallite size, and band gap of bismuth oxybromides. The formation of Bi-based complexes and degraded urea-based products were observed, which were deduced to influence band gap energies and hence, photoactivity. Predominantly, samples prepared at low urea ratios proved to be the best for both rhodamine B and ibuprofen degradations under both irradiations.

Facile and scalable construction of nitrogen-doped lignin-based carbon nanospheres for high-performance supercapacitors

Lignin-based carbon nanospheres have a high specific surface area, large porosity, and excellent stability, while being used in potential applications such as catalyst carriers, adsorbents, and energy storage materials. However, the low hydrophilicity and poor chemical activity of pure carbon nanospheres make it challenging for those materials to meet the needs of various functions. The introduction of nitrogen atoms can increase the active site of the materials, thereby improving the performance. In this study, lignin nanospheres (LNS) with a solid content of 5.8 mg mL−1 in the suspension and an actual yield of 85% were prepared using a γ-valerolactone/water binary system. Based on that, nitrogen-doped lignin-based carbon nanospheres (NCS) were successfully constructed. The doping ratio of urea and carbonization temperature significantly affected the physicochemical properties of the carbon materials. By varying the urea doping ratio and temperature, the nitrogen atom content of the NCS varied from 5.0 to 10.9 at.%. After assembling them into electrochemical capacitors, NCS-15–700 exhibited excellent capacitance of 232 F g−1 at 0.5 A g−1 and 10,000 cycles long cycling stability (retention of 97.2%). The specific capacitance was enhanced by approximately 40% compared to undoped lignin-based carbon nanospheres (LCS). It is evident that nitrogen-doped lignin-based carbon nanospheres have promising applicability in supercapacitors.

Effects of Addition of Tea Polyphenol Palmitate and Process Parameters on the Preparation of High-Purity EPA Ethyl Ester.

High-purity eicosapentaenoic acid (EPA) ethyl ester (EPA-EE) can be produced from an integrated technique consisting of saponification, ethyl esterification, urea complexation, molecular distillation and column separation. In order to improve the purity and inhibit oxidation, tea polyphenol palmitate (TPP) was added before the procedure of ethyl esterification. Furthermore, through the optimization of process parameters, 2:1 (mass ratio of urea to fish oil, g/g), 6 h (crystallization time) and 4:1 (mass ratio of ethyl alcohol to urea, g/g) were found to be the optimum conditions in the procedure of urea complexation. Distillate (fraction collection), 115 °C (distillation temperature) and one stage (the number of stages) were found to be the optimum conditions for the procedure of molecular distillation. With the addition of TPP and the above optimum conditions, high-purity (96.95%) EPA-EE was finally obtained after column separation.

Sılıcon Based Gel to Shut-Off of Water in the Well-Bore

The quality of gel - based silicon, which forms an insulating content to prevent water and sand in oil and gas wells, have been improved. Based on the reaction between the liquid glass and hydrochloric acid, the optimal concentration of the initial reagents for the formation of the gel process was determined. The rheology, initial and final setting time of the silicon based gel, and the temperature dependencies of the gel forming process were also studied by adding 0.1-1.0% (mass ratio) of urea as cross-linking to the Na2SiO3/HCl solution. At the same time, the impact of the obtained gel of the permeability of the rock pores was determined and the filtration characteristics were studied. It has been determined that with 0.1-0.8% mass concentration of the urea added to the Na2SiO3/HCl solution, the setting time of the gel could be regulated according to the well-layer regime. The resulting silicone-based gel can be used as an injection solution that can set in 3-22 hours in oil and gas wells between the temperature of 20-80 °C.

Cryoprotection in Human Mesenchymal Stromal/Stem Cells: Synergistic Impact of Urea and Glucose

Standard freezing protocols of clinically relevant cell lines commonly employ agents such as fetal bovine serum and dimethyl sulfoxide, which are a potential concern from both a regulatory and a patient safety perspective. The aim of this work was to develop formulations with safe and well tolerated excipients for the (cryo-) preservation of cell therapy products. We evaluated the cryoprotective capabilities of urea and glucose through measurements of cell metabolic activity. Freezing of clinically relevant human mesenchymal stromal/stem cells and human dermal fibroblasts at ≤ - 65°C at equimolar ratios of urea and glucose resulted in comparable viabilities to established dimethyl sulfoxide. Pre-incubation of human mesenchymal stromal/stem cells in trehalose and addition of mannitol and sucrose to the formulation further enhanced cell viability after freeze-thaw stress. Other cell types assessed (A549 and SK-N-AS) could not satisfactorily be preserved with urea and glucose, highlighting the need for tailored formulations to sustain acceptable cryopreservation.