Urea Production Research Articles

INCREASING THE EFFICIENCY OF THE SYSTEMS OF COMPRESSOR-PUMPING AND REFRIGERATION UNITS SUPPLYING LIQUID CO2 AND NH3 TO THE UNIT FOR CARBAMIDE SYNTHESIS

Carbon dioxide is used in large volumes to produce urea, a highly efficient nitrogen fertilizer. It is compressed in a multistage compressor to a pressure of 15 MPa and fed to the urea synthesis unit. The specific energy consumption for the compression of carbon dioxide by a compressor reaches 0.16 kWh/kg. It may be more profitable to use in the system of compressor-pumping and refrigeration units. They can be used to liquefy carbon dioxide and compress it to pressure 15 MPa before feeding it to the synthesis of urea. In the simplest scheme, an ammonia compression refrigeration machine (ACRM) is included in the system to improve efficiency. The specific energy consumption in such a system for the liquefaction and compression of CO2 is 0.118 kWh/kg. In case of replacement of the ACRM with an absorption refrigeration machine, unit costs can be reduced to 0.09 kWh/kg. These two systems can be used to increase urea production or to ensure stable operation of the units during the summer period of their operation. The analysis showed that further improvement of the technological scheme of the entire system will completely abandon the use of the compressor method of compression of CO2 to pressure 15 MPa before its supply to the urea synthesis unit. To do this, you need to include an additional absorption lithium bromide refrigeration machine in the system. In this scheme, the compressor-pumping unit will provide the simultaneous supply of liquid carbon dioxide and ammonia for the synthesis of urea with a pressure of 15 MPa. To increase the daily production of urea from 1400 to 2000 tons, it is necessary to increase the feed liquid CO2 in the amount of 62 t/hour and liquid NH3 — 47.5 t/hour. Bibl. 14, Fig. 3.

Nitrogen Balance after the Administration of a Prolonged-Release Protein Substitute for Phenylketonuria as a Single Dose in Healthy Volunteers.

Nitrogen balance is the difference between nitrogen excreted as urea and nitrogen ingested, mainly in proteins. Increased circulating concentrations of amino acids (AA) in the bloodstream are usually associated with proportional increases in the production and excretion of urea. Previously, we reported results from a randomized, controlled, single-dose, crossover trial in healthy adult volunteers (n = 30) (Trial Registration: ISRCTN11016729), in which a Test product (prolonged-release AA mixture formulated with Physiomimic Technology™ (PT™)) significantly slowed down the release and reduced the peak plasma concentrations of essential AAs compared with a free AA mixture (Reference product) while maintaining essential AA bioavailability. Here, we report an assessment of the nitrogen balance from the same study. The amount of nitrogen contained in plasma AAs, levels of blood urea nitrogen (BUN) (p < 0.0001) and changes in BUN (p < 0.0001) were smaller after the Test product compared with the Reference product. These findings suggest that the production of urea in proportion to systemic AA availability was significantly smaller after the administration of the Test product compared with the Reference product and that the test product conferred the increased utilization of AAs for protein synthesis and reduced their oxidation and conversion to urea. In the clinical setting, it is possible that the effects of PT™ observed on the disposition of free AAs in this study may translate to health benefits in terms of physiological body composition and growth if used for the treatment of subjects with phenylketonuria (PKU). Further investigation in patients with PKU is warranted.

An integrated biomimetic array chip for establishment of collagen-based 3D primary human hepatocyte model for prediction of clinical drug-induced liver injury.

Drug-induced liver injury (DILI) is a leading cause of therapy failure in the clinic and also contributes much to acute liver failure cases. Investigations of predictive sensitivity in animal models have limitations due to interspecies differences. Previously reported in vitro models of liver injury based on primary human hepatocytes (PHHs) cannot meet the requirements of high physiological fidelity, low cost, simple operation, and high throughput with improved sensitivity. Herein, we developed an integrated biomimetic array chip (iBAC) for establishing extracellular matrix (ECM)-based models. A collagen-based 3D PHH model was constructed on the iBAC as a case for the prediction of clinical DILI at throughput. The iBAC has a three-layer structure with a core component of 3D implanting holes. At an initial cell seeding numbers of 5000-10,000, the collagen-based 3D PHH model was optimized with improved and stabilized liver functionality, including cell viability, albumin, and urea production. Moreover, basal activities of most metabolic enzymes on the iBAC were maintained for at least 12 days. Next, a small-scale hepatotoxicity screening indicated that the 3D PHH model on the iBAC was more sensitive for predicting hepatotoxicity than the 2D PHH model on the plate. Finally, a large-scale screening of liver toxicity using 122 clinical drugs further demonstrated that the collagen-based 3D PHH model on the iBAC had superior predictive sensitivity compared to all previously reported in vitro models. These results indicated the importance of 3D collagen for liver physiological functionality and hepatotoxicity prediction. We anticipant it being a promising tool for risk assessment of drug-induced hepatotoxicity with a widespread acceptance in drug industry.

Carbon dioxide abatement by integration of methane bi-reforming process with ammonia and urea synthesis

The use of thermal power plants has been increasing lately, despite its use being associated with high greenhouse gases emissions, especially carbon dioxide. In the context of the Paris Agreement of 2015, carbon dioxide capture, storage and utilization techniques must be increasingly employed to reduce environmental impacts. The utilization of carbon dioxide from a power plant flue gas as feedstock to other chemicals synthesis (such as ammonia and urea) arises as a good alternative to achieve near-zero carbon dioxide emissions. The aim of this work is to propose an alternative route, based on the bi-reforming of methane, for the synthesis gas section of ammonia and urea production plants, in order to promote carbon dioxide abatement, comparing this innovative route with the conventional and century-long existing process. Technical and environmental metrics of the proposed and conventional routes were compared. Aspen Plus® process simulator was used to simulate the bi-reforming process and both routes for ammonia and urea synthesis and choose the operational parameters. Simulation results show that for a target production of 2000 tonne/day of urea, the proposed alternative route has the potential to abate 745 tonne/day of carbon dioxide, while the conventional route emits 1156 tonne/day of carbon dioxide. Comparison of technical metrics of both routes shows that the proposed route requires an electricity usage of 0.27 MWh/tonne of products while the conventional route requires 0.47 MWh/tonne of products. However, hydrogen yield in the conventional route is higher than in its counterpart, with 0.41 and 0.22 tonnes of hydrogen produced for each tonne of inlet natural gas in the conventional and proposed routes, respectively. Comparison of economic metrics of both configurations show that none of the routes are economically viable, however, the alternative route has better economic indicators besides successfully promotes carbon dioxide abatement.

Commercially Available Non-Saccharomyces Yeasts for Winemaking: Current Market, Advantages over Saccharomyces, Biocompatibility, and Safety

About 42 commercial products based on non-Saccharomyces yeasts are estimated as available on the market, being mostly pure cultures (79%), with a predominance of Torulaspora delbrueckii, Lachancea thermotolerans, and Metschnikowia pulcherrima. The others are multi-starter consortia that include non-Saccharomyces/Saccharomyces mixtures or only non-Saccharomyces species. Several commercial yeasts have shown adequate biocompatibility with S. cerevisiae in mixed fermentations, allowing an increased contribution of metabolites of oenological interest, such as glycerol, esters, higher alcohols, acids, thiols, and terpenes, among others, in addition to a lower production of acetic acid, volatile phenols, biogenic amines, or urea. Multi-starter inoculations are also reviewed here, which show adequate biocompatibility and synergy between species. In certain cases, the aromatic profile of wines based on grape varieties considered neutral is improved. In addition, several yeasts show the capacity as biocontrollers against contaminating microorganisms. The studies conducted to date demonstrate the potential of these yeasts to improve the properties of wine as an alternative and complement to the traditional S. cerevisiae.

The life cycle environmental impacts of a novel sustainable ammonia production process from food waste and brown water

To replace existing high impact ammonia production technologies, a new sustainability-driven waste-based technology producing green ammonia with and without urea was devised using life cycle thinking and sustainable design principles, targeting efficiency, carbon emissions, water, and power use competitiveness. We have used life cycle assessment to determine whether cradle-to-gate, multiple configurations of the core waste-based processes integrating several carbon capture/utilization options can compete environmentally with other available ammonia technologies. Our waste-to-ammonia processes reduce potential impacts from abiotic depletion, human toxicity, and greenhouse gas (GHG) emissions relative to fossil-based and renewable technologies. Among the assessed technologies, coupling dark fermentation with anaerobic digestion and capturing CO2 for sequestration or later use is most efficient for GHGs, water, and energy, consuming 27% less energy and reducing GHGs by 98% compared to conventional ammonia. Water use is 38% lower than water electrolysis and GHGs are 94% below municipal waste incineration routes per kg NH3. Additionally, displacing conventional, high impact urea by integrating urea production from process CO2 decreases life cycle environmental impacts significantly despite increased energy demand. On a fertilizer-N basis, the ammonia + urea configuration without dark fermentation performs best on all categories included. Methane and ammonia leakage cause nearly all life cycle impacts, indicating that failing to prevent leakage undermines the effectiveness of new technologies such as these. Our results show that a green ammonia/ammonia + urea process family as designed here can reduce waste and prevent the release of additional CO2 from ammonia production while avoiding fossil-based alternatives and decreasing emissions from biogenic waste sources.

Selective electrocatalytic synthesis of urea with nitrate and carbon dioxide

Synthetic nitrogen fertilizer such as urea has been key to increasing crop productivity and feeding a growing population. However, the conventional urea production relies on energy-intensive processes, consuming approximately 2% of annual global energy. Here, we report on a more-sustainable electrocatalytic approach that allows for direct and selective synthesis of urea from nitrate and carbon dioxide with an indium hydroxide catalyst at ambient conditions. Remarkably, Faradaic efficiency, nitrogen selectivity and carbon selectivity reach 53.4%, 82.9% and ~100%, respectively. The engineered surface semiconducting behaviour of the catalyst is found to suppress hydrogen evolution reaction. The key step of C–N coupling initiates through the reaction between *NO2 and *CO2 intermediates owing to the low energy barrier on {100} facets. This work suggests an appealing route of urea production and provides deep insight into the underlying chemistry of C–N coupling reaction that could guide sustainable synthesis of other indispensable chemicals.

Electrochemical synthesis of urea on MBenes

Urea is an important raw material in the chemical industry and is widely used as a nitrogen source in chemical fertilizers. The current industrial urea synthesis not only requires harsh reaction conditions, but also consumes most of the NH3 obtained through artificial synthesis. The conversion of N2 and CO2 into urea through electrochemical reactions under ambient conditions represents a novel green urea synthesis method. However, the large-scale promotion of this method is limited by the lack of suitable electrocatalysts. Here, by means of density functional theory computations, we systematically study the catalytic activity of three experimentally available two-dimensional metal borides (MBenes), Mo2B2, Ti2B2, and Cr2B2 toward simultaneous electrocatalytic coupling of N2 and CO2 to produce urea under ambient conditions. According to our results, these three MBenes not only have superior intrinsic basal activity for urea formation, with limiting potentials ranging from −0.49 to −0.65 eV, but also can significantly suppress the competitive reaction of N2 reduction to NH3. In particular, 2D Mo2B2 and Cr2B2 possess superior capacity to suppress surface oxidation and self-corrosion under electrochemical reaction conditions, rendering them relatively promising electrocatalysts for urea production. Our work paves the way for the electrochemical synthesis of urea.

Abstract 2334: Discovery of selective inhibitors of carbamoyl phosphate synthetase I (CPS1) to modulate cancer relevant metabolic pathways

Abstract Carbamoyl Phosphate Synthetase 1 (CPS1) catalyzes the first and rate-limiting step in ammonia detoxification through the urea cycle, generating carbamoyl phosphate from ammonia, bicarbonate and ATP. CPS1 is overexpressed in several cancers, including LKB1-deficient non-small cell lung carcinoma (NSCLC), where its activity has been proposed to support tumor growth by generating carbamoyl phosphate for use in pyrimidine synthesis. In other cancers, CPS1 has been reported to remove toxic ammonia from growing tumors to allow for sustained growth. Currently, no small molecule inhibitors of CPS1 have been identified, limiting researcher's ability to dissect the involvement of CPS1 function in cancer biology. We describe here the discovery of the first known small molecule inhibitors of CPS1. From a high throughput screen, we identify two chemical series, which achieve inhibition of CPS1 by blocking bicarbonate phosphorylation in the first step of carbamoyl phosphate synthesis. Biochemical experiments reveal inhibition of bicarbonate phosphorylation occurs through competition between inhibitor and ATP. High-resolution co-crystal structures demonstrate that these novel inhibitors bind to a previously unidentified allosteric pocket located between the integrating domain and carbamate synthetase domain of CPS1. This allosteric mechanism of action allows for highly selective CPS1 inhibition, with no inhibition of CPS2 observed. Analogs with increased potency were developed, which are able to inhibit CPS1 cellular activity, blocking both urea production and the CPS1-mediated pyrimidine biosynthetic pathway in cultured cells. These novel CPS1 inhibitors are valuable, first-in-class tools for probing CPS1 biology. We will also discuss the opportunity to utilize these novel inhibitors of CPS1, along with genetic approaches, to probe the functional roles of CPS1 in LKB1-deficient NSCLC. Citation Format: Shihua Yao, Tuong-Vi Nguyen, Alan Rolfe, Anant A. Agrawal, Jiyuan Ke, Shouyong Peng, Federico Colombo, Sean Yu, Patricia Bouchard, Jiayi Wu, Kuan-Chun Huang, Xingfeng Bao, Kiyoyuki Omoto, Anand Selvaraj, Lihua Yu, Stephanos Ioannidis, Frédéric H. Vaillancourt, Ping Zhu, Nicholas A. Larsen, David M. Bolduc. Discovery of selective inhibitors of carbamoyl phosphate synthetase I (CPS1) to modulate cancer relevant metabolic pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2334.

Chamomile flower extract ameliorates biochemical and histological kidney dysfunction associated with polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is the most prevalent endocrine disorder in females of childbearing age and research findings have revealed a potential association between PCOS and renal dysfunction. This study aimed to investigate renal dysfunction that might be associated with PCOS in rats and to evaluate the potential protective effect of chamomile against PCOS complicated by kidney damage. A rat model of PCOS was induced by injecting estradiol valerate (0.2mg/rat×2) into adult virgin female rats. Rats were treated with either ethyl alcohol extract of chamomile flower (75mg/kg/day) or metformin (Met) (500mg/kg/day). Induction of PCOS was associated with increased relative right kidney weight percentage and increased serum levels of urea, lipid peroxide product, and testosterone. PCOS was also associated with increased p53 expression in kidney glomeruli and medullary tubules with decreased Bcl2 expression in kidney glomeruli. Administration of chamomile extract significantly decreased levels of serum urea, testosterone, and lipid peroxide product, and p53 expression in kidney glomeruli and tubules. The extract significantly increased levels of antioxidant markers levels (reduced glutathione, catalase, and superoxide dismutase) and the expression of the anti-apoptotic gene Bcl2. Conversely, administration of Met did not improve serum levels of urea. Met also exerted no pronounced effect on p53 gene expression. The results of this study highlight the importanceofmonitoringkidney function in patients with PCOS and investigating the associated underlying mechanism. Chamomile extract was found to ameliorate kidney damage associated with PCOS through antioxidant, testosterone-lowering, and anti-apoptotic mechanisms.

Understanding the impact of more realistic low-dose, prolonged engineered nanomaterial exposure on genotoxicity using 3D models of the human liver

BackgroundWith the continued integration of engineered nanomaterials (ENMs) into everyday applications, it is important to understand their potential for inducing adverse human health effects. However, standard in vitro hazard characterisation approaches suffer limitations for evaluating ENM and so it is imperative to determine these potential hazards under more physiologically relevant and realistic exposure scenarios in target organ systems, to minimise the necessity for in vivo testing. The aim of this study was to determine if acute (24 h) and prolonged (120 h) exposures to five ENMs (TiO2, ZnO, Ag, BaSO4 and CeO2) would have a significantly different toxicological outcome (cytotoxicity, (pro-)inflammatory and genotoxic response) upon 3D human HepG2 liver spheroids. In addition, this study evaluated whether a more realistic, prolonged fractionated and repeated ENM dosing regime induces a significantly different toxicity outcome in liver spheroids as compared to a single, bolus prolonged exposure.ResultsWhilst it was found that the five ENMs did not impede liver functionality (e.g. albumin and urea production), induce cytotoxicity or an IL-8 (pro-)inflammatory response, all were found to cause significant genotoxicity following acute exposure. Most statistically significant genotoxic responses were not dose-dependent, with the exception of TiO2. Interestingly, the DNA damage effects observed following acute exposures, were not mirrored in the prolonged exposures, where only 0.2–5.0 µg/mL of ZnO ENMs were found to elicit significant (p ≤ 0.05) genotoxicity. When fractionated, repeated exposure regimes were performed with the test ENMs, no significant (p ≥ 0.05) difference was observed when compared to the single, bolus exposure regime. There was < 5.0% cytotoxicity observed across all exposures, and the mean difference in IL-8 cytokine release and genotoxicity between exposure regimes was 3.425 pg/mL and 0.181%, respectively.ConclusionIn conclusion, whilst there was no difference between a single, bolus or fractionated, repeated ENM prolonged exposure regimes upon the toxicological output of 3D HepG2 liver spheroids, there was a difference between acute and prolonged exposures. This study highlights the importance of evaluating more realistic ENM exposures, thereby providing a future in vitro approach to better support ENM hazard assessment in a routine and easily accessible manner.

Urea Melt Marbles Developed by Enwrapping Urea Melt Droplets with Superhydrophobic Particles: Preparation, Properties, and Application in Large Urea Granule Production

AbstractUrea melt droplets (UMDs) spontaneously spheronize and form large urea granules after condensation on superhydrophobic surfaces without dust generation. However, they break and coalesce when colliding with each other; moreover, they adhere to the surface and form tails when rolling. These problems limit the practicality of the process using UMDs for large urea granulation directly. Urea melt marbles (UMMs) are introduced to overcome these drawbacks by enwrapping UMDs with superhydrophobic polytetrafluoroethylene (PTFE) powder, thus enhancing the elasticity and maintaining the sphericity. A premixing–melting process is developed to obtain UMMs and lower the PTFE powder consumption to half of that required in the traditional liquid marble preparation. The best determined elasticity modulus of UMMs reaches 44.9 ± 3.6 Pa, and the sphericity is 0.9992. No adhering or tailing occurs during rolling granulation. Large urea granules obtained through UMMs meet all requirements for the commercial urea products and exhibit additional advantages of protection against moisture and slow release of fertilizer.

Life Cycle Analysis for The Production of Urea Through Syngas

For optimum growth of the agriculture industry certain urea-based fertilizers are used to provide better Nitrogen content to the soil, but this growth comes with a cost in terms of carbon footprint. In this paper, life cycle assessment (LCA) is conducted for urea production having a minimum of 46% nitrogen content. For LCA, a fertilizer industry with 3850 MTPD urea production capacity is considered with an annual target of 1.27 MMTPA, while the functional unit is taken as 1MT of urea production. This paper is concerned about finding the MT equivalent CO2 required per MT urea production. The coal used for syngas preparation is from G9 to G14 meaning the gross calorific value (GCV) ranges from 4601 to 3400 GCV per kilocalories. The carbon footprint of catalyst is considered and showed its importance when it comes to larger production size. In this analysis, MT CO2equivalent per MT urea is 0.714and this result is also compared with the data of the developing countries.

A highly carbon‐efficient and techno‐economically optimized process for the renewable‐assisted synthesis of gas to liquid fuels, ammonia, and urea products

Carbon dioxide conversion into beneficial products has received very much attention in recent years to decrease industrial CO2 emissions. In this context, integration of gas to liquids (GTL) process with an iron-based Fischer-Tropsch (FT) reactor with ammonia and urea synthesis plants was investigated. The main motivation of the proposed integration is to reuse a released CO2 stream from the GTL process and to enhance the commercial process economy. The required hydrogen for ammonia comes from polymer electrolyte membrane (PEM) electrolyzers running by solar power. Latin hypercube design (LHD) approach was applied to model the profitability and carbon efficiency of the process. Optimization was conducted to maximize the carbon efficiency and profit index of the overall process using the model-based calibration (MBC) toolbox of MATLAB. The results demonstrated that at the optimum case, the proposed integration is capable of producing 48 t/h of urea and also utilizing about 35 t/h of CO2 produced in the GTL process. The results were compared with another configuration in which a cobalt-based FT reactor was integrated with ammonia and urea processes. The results suggest that profitability, carbon efficiency, and urea production of the process configuration with a Co-based FT reactor is higher than the iron-based configuration while the wax production rate of the iron-based configuration is higher than that of the Co-based process. Techno-economic feasibility study of the zero CO2 emission process represents that the carbon efficiency of around 100% could be obtained.

Liver-lobule-mimicking patterning via dielectrophoresis and hydrogel photopolymerization

Patterning and cultivating heterogeneous cells on microfluidic chips is essential for engineering tissue regeneration. Current patterning technologies focus mainly on positioning cells at specific locations, but most do not mimic in-vivo cell patterns. Even few papers and reports care about maintaining cell patterns after the patterning process and several days of culture. Here, we report a liver-lobule-mimicking labchip consisting of three components: the concentration gradient generator, the dielectrophoretic cell-patterning, and four cell-culturing chambers providing culturing microenvironment. NIH/3T3 (fibroblast cell) and C3A cells (human hepatocyte) were patterned via dielectrophoresis to reconstruct the liver-lobule’s radial actinomorphic organization and pattern at each cell-culture chamber. Subsequently, GelMA at different concentrations was perfused to form GelMA culturing-microenvironment coverings with different concentrations of 5 %, 10 %, 15 % GelMA and 0 % GelMA for the control group. Cell viability was maintained 95 % at 5 % GelMA chamber after cultured for 72 h. For the 15 % GelMA chamber, cell viability was 78 % on 72-hrs culturing. Urea assays revealed that the co-cultured cells in 5 % GelMA maintained the high activity, which has the highest urea secretion, with the preserved biomimicking liver-lobule pattern compared with other culturing-microenvironments. By cultivating cells in our liver-lobule-mimicking labchip with cellular micropatterning and hydrogel covering, the liver-lobule-like cell pattern was not affected by the difference in cell growth rate and the streamline of the perfused culture medium. We also observed that the appropriate GelMA culturing-microenvironment not only preserves the biomimicking liver-lobule pattern but also enhances liver function related to urea production.

Photoluminescence with an unusual open-loop and rigid delocalized conjugated structure in quantum dots

It is well known that almost all photoluminescent molecules are aromatic or heterocyclic ring compounds for bioimaging analysis. A question remains as to whether a breakthrough can be achieved regarding a novel photoluminescent molecule without a ring structure, and in a what manner. In this study, we explored the photoelectric conversion and structure of photoluminescent compounds, and constructed an intra-molecular coupling positive–negative-junction (PNJ) with an open-loop and rigid Π56 delocalized conjugated structure of the coupling p-π conjugate system. This was performed to enable strong absorption of the R/tail-end band for the high probability of an n → π*/n → σ* electron transition for photoluminescence production. Subsequently, the Π56 structure was formed in a short-chain aliphatic molecule as a hydrolytic product of citric acid and urea, and computational methodology was employed to estimate the feasibility of the molecule photoluminescence. Finally, a quantum dot material was fabricated from the aliphatic molecule, the optical properties of the quantum dots were investigated, and the biocompatibility and bioimaging ability of quantum dots were assessed. This work presents not only a theoretical exploration but also practical application of a new strategy to obtain molecules, compounds, and materials with bioimaging.

Metabolomic markers predictive of hepatic adaptation to therapeutic dosing of acetaminophen

Background Drug induced liver injury (DILI) remains a prominent global issue and acetaminophen (APAP) overdose represents a common cause of hepatic injury and DILI. Transient alanine aminotransferase (ALT) elevations have been documented while adhering to recommended daily dosing. However, no metabolites have been identified in pre-treatment samples predicting which patients will develop these transient increases. Methods This was a secondary analysis of samples collected from a parent study describing the course of ALT levels in subjects receiving therapeutic APAP dosing. Two hundred and four subjects recruited from Denver, Colorado received 4 g APAP/daily for at least 16 days. Subjects were grouped by ALT at any monitored time point above 60 units/L (n = 25) vs. no increase (n = 179). Serum samples from days 0, 7, 16, and 31 were run on ultra-high performance liquid chromatography mass spectrometry. We report the metabolomic results of samples analyzed prior to APAP administration and over time. Significant changes in metabolite and demographic variable expressions were explored using t-tests with false discovery rate correction, chi square, and partial least squares discriminant analyses. Results Within pre-treatment day 0 samples, allantoate and ornithine were significantly elevated in subjects of the ALT elevation group (p = .032). Baseline ALT (p = .011) and alkaline phosphatase (p = .006) were also significant. These metabolites were significant independent of race, ethnicity, gender, or BMI. Conclusions Allantoate and ornithine are directly involved in pathways related to nitrogen release and urea production. Further investigation into alterations in the glutathione metabolism and urea cycle pathways may lead to a greater understanding of the mechanisms associated with hepatic adaptation for a variety of pharmaceuticals.

Nutritive Value, In Vitro Fermentation, and Methane Production of Cactus Cladodes, Sugarcane Bagasse, and Urea.

Simple SummaryCyclical droughts affecting arid and semiarid regions promote direct negative impacts on agriculture, with deficits of water availability for the maintenance of crops destined for human supply and animal production, with direct and indirect socioeconomic effects. Although livestock rearing is one of the few viable economic activities for these regions, forage production in terms of quantity and quality is a critical obstacle to support the herd over the year. Research was developed to find a forage adapted to these climates. Cactus cladodes have been used as a traditional ingredient in ruminant diets in dry areas as a solution to forage scarcity. Many traditionally used sources of forage, fresh or conserved, can be added to diets with cactus. However, the limiting factor to their inclusion would be market availability and price. This study showed that cactus cladodes associated with sugarcane bagasse (a high available crop residue) present the same nutritive value of conserved crops as silages and hay. Cactus (Opuntia and Nopalea) are essential for ruminant production systems in arid and semiarid regions due to the limitation of forage production caused by the low precipitation.This study evaluated the effect of different roughages fed to sheep on nutrient and water intake, ingestive behavior, nitrogen balance, microbial protein synthesis, fermentation parameters, and methane production using an in vitro gas production system. The treatments consisted of five diets: cactus cladodes Nopalea (NUB) and Opuntia (OUB), both with the addition of sugarcane bagasse (SB) and urea/ammonium sulfate (urea/as); Tifton hay (TH); corn silage (CS); and sorghum silage (SS), also with added urea/as. The NUB provided greater (p ≤ 0.03) intakes of dry matter (1024 g/d), digestible organic matter (670 g/d), and crude protein (161 g/d) than those on the SS. The NUB provided greater (p < 0.01) dietary water intake (3023 g/d) than TH. The time spent on rumination was shorter (p < 0.01), and the idle time was longer in animals fed NUB and OUB than TH and CS. Microbial protein synthesis was not affected (p = 0.27). The final pH (6.4) of the incubation fluid and the concentration of NH3-N (39.05 mg/dL) were greater for NUB and OUB. Ruminal parameters and methane production were little or not affected by tested forages. We recommend using cactus cladodes in combination with sugarcane bagasse and urea/as in sheep diets.

Molecular insight into optimizing the N- and P-doped fullerenes for urea removal in wearable artificial kidneys

Urea is the result of the breakdown of proteins in the liver, the excess of which circulates in the blood and is adsorbed by the kidneys. However, in the case of kidney diseases, some products, specifically urea, cannot be removed from the blood by the kidneys and causes serious health problems. The end-stage renal disease (ESRD) patients are not able to purify their blood, which endangers their life. ESRD patients require dialysis, a costly and difficult method of urea removal from the blood. Wearable artificial kidneys (WAKs) are consequently designed to remove the waste from blood. Regarding the great amount of daily urea production in the body, WAKs should contain strong and selective urea adsorbents. Fullerenes—which possess fascinating chemical properties—have been considered herein to develop novel urea removal adsorbents. Molecular dynamics (MD) has enabled researchers to study the interaction of different materials and can pave the way toward facilitating the development of wearable devices. In this study, urea adsorption by N-doped fullerenes and P-doped fullerenes were assessed through MD simulations. The urea adsorption was simulated by five samples of fullerenes, with phosphorous and different nitrogen dopant contents. For comparing the urea adsorption capacity in the performed simulations, detailed characteristics—including the energy analysis, radius of gyration, radial distribution function (RDF), root-mean-square fluctuation (RMSD), and H-bond analyses were investigated. It had been determined that the fullerene containing 8% nitrogen—with the highest reduction in the radius of gyration, the maximum RDF, a high adsorption energy, and a high number of hydrogen bonds—adsorbs urea more efficiently.

Hypertension due to loss of water

In the current issue of Acta Physiologica, two papers are published investigating the development of arterial hypertension under conditions of pathological loss of free water in two disease models. Kovaric et al 1 studied rats with chronic renal failure, shedding excessive free water via their remnant kidney due to a hypostenuric concentrating defect. Wild et al. 2 investigated a transgenic mouse model for psoriasis, losing free water via the psoriatic skin lesions. In both cases the animals displayed hypertension, cutaneous vasoconstriction, and metabolic adaptations towards enhanced production of urea and organic osmolytes typical for a phylogenetically ancient water conservation response termed aestivation 3 . The international consortia of investigators spearheaded by Titze, Karbach, and Kitada therefore conclude that in both cases the hypertension was due to cutaneous vasoconstriction in an attempt to limit epidermal water loss. Because in either case the hypertension was associated with loss of water, and thus with hypo- rather than hypervolemia, the authors argue, that this concept of pathogenesis of hypertension is antipodal to the classic view that relies on hypervolemia due to sodium retention.