Every late autumn, fluttering poplar leaves scatter throughout the campus and city streets. In this work, poplar leaves were used as the raw material, while Hsub.3POsub.4 and KOH were used as ...activators and urea was used as the nitrogen source to prepare biomass based-activated carbons (ACs) to capture COsub.2. The pore structures, functional groups and morphology, and desorption performance of the prepared ACs were characterized; the COsub.2 adsorption, regeneration, and kinetics were also evaluated. The results showed that Hsub.3POsub.4 and urea obviously promoted the development of pore structures and pyrrole nitrogen (N–5), while KOH and urea were more conductive to the formation of hydroxyl (–OH) and ether (C–O) functional groups. At optimal operating conditions, the COsub.2 adsorption capacity of Hsub.3POsub.4– and KOH–activated poplar leaves after urea treatment reached 4.07 and 3.85 mmol/g, respectively, at room temperature; both showed stable regenerative behaviour after ten adsorption–desorption cycles.
Information on the homogeneity and distribution of .sup.13 carbon (.sup.13 C) and nitrogen (.sup.15 N) labeling in winter wheat (Triticum aestivum L.) is limited. We conducted a dual labeling ...experiment to evaluate the variability of .sup.13 C and .sup.15 N enrichment in aboveground parts of labeled winter wheat plants. Labeling with .sup.13 C and .sup.15 N was performed on non-nitrogen fertilized (-N) and nitrogen fertilized (+N, 250 kg N ha.sup.-1 ) plants at the elongation and grain filling stages. Aboveground parts of wheat were destructively sampled at 28 days after labeling. As winter wheat growth progressed, delta.sup.13 C values of wheat ears increased significantly, whereas those of leaves and stems decreased significantly. At the elongation stage, N addition tended to reduce the aboveground delta.sup.13 C values through dilution of C uptake. At the two stages, upper (newly developed) leaves were more highly enriched with .sup.13 C compared with that of lower (aged) leaves. Variability between individual wheat plants and among pots at the grain filling stage was smaller than that at the elongation stage, especially for the -N treatment. Compared with those of .sup.13 C labeling, differences in .sup.15 N excess between aboveground components (leaves and stems) under .sup.15 N labeling conditions were much smaller. We conclude that non-N fertilization and labeling at the grain filling stage may produce more uniformly .sup.13 C-labeled wheat materials, whereas the materials were more highly .sup.13 C-enriched at the elongation stage, although the delta.sup.13 C values were more variable. The .sup.15 N-enriched straw tissues via urea fertilization were more uniformly labeled at the grain filling stage compared with that at the elongation stage.
Urea is the major end product of nitrogen metabolism in humans, which is eliminated from the body mainly by the kidneys through urine but is also secreted in body fluids such as blood and saliva. Its ...level in urine ranges from 7 to 20 mg/dL, which drastically rises under patho-physiological conditions thus providing key information of renal function and diagnosis of various kidney and liver disorders. Increase in urea levels in blood, also referred to as azotemia or uremia. The chronic kidney disease (CKD) or end stage renal disease (ESRD) is generally caused due to the progressive loss of kidney function. Hence, there is an urgent need of determination of urea in biological fluids to diagnose these diseases at their early stage. Among the various methods available for detection of urea, most are complicated and require time-consuming sample pre-treatment, expensive instrumental set-up and trained persons to operate, specifically for chromatographic methods. The biosensing methods overcome these drawbacks, as these are simple, fast, specific and highly sensitive and can also be applied for detection of urea in vivo. This review presents the principles of various analytical methods for determination of urea with special emphasis on biosensors. The use of various nanostructures and electrochemical microfluidic paper based analytical device (EμPAD) are suggested for further development of urea biosensors.
•Review illustrates classification of urea biosensors with their analytical performances.•The use of various nanomaterials in fabrication of urea biosensor has been discussed.•Fabrication of low cost urea biosensors along with their improved sensitivity and stability has been discussed.•The future research could be focused on miniaturization of urea biosensors.
With the exponential growth of the global population, the agricultural sector is bound to use ever larger quantities of fertilizers to augment the food supply, which consequently increases food ...production costs. Urea, when applied to crops is vulnerable to losses from volatilization and leaching. Current methods also reduce nitrogen use efficiency (NUE) by plants which limits crop yields and, moreover, contributes towards environmental pollution in terms of hazardous gaseous emissions and water eutrophication. An approach that offsets this pollution while also enhancing NUE is the use of controlled release urea (CRU) for which several methods and materials have been reported. The physical intromission of urea granules in an appropriate coating material is one such technique that produces controlled release coated urea (CRCU). The development of CRCU is a green technology that not only reduces nitrogen loss caused by volatilization and leaching, but also alters the kinetics of nitrogen release, which, in turn, provides nutrients to plants at a pace that is more compatible with their metabolic needs. This review covers the research quantum regarding the physical coating of original urea granules. Special emphasis is placed on the latest coating methods as well as release experiments and mechanisms with an integrated critical analyses followed by suggestions for future research.
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Invited for the cover of this issue is the group of Bo Wang at Biogen. The image depicts the sectored chiral domains of urea inclusion compounds. Read the full text of the article at ...10.1002/chem.202302217.
Among patients with heart failure and a reduced ejection fraction, those who received the cardiac myosin activator omecamtiv mecarbil had a lower incidence of a composite of heart-failure events or ...cardiovascular death at a median of 22 months than those who received placebo.
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•The Ni5P4 nanosheets exhibit crystalline@amorphous core–shell structure.•The amorphous shell renders the CA-Ni5P4@NiOx/NF electrode superhydrophilic.•CA-Ni5P4@NiOx/NF exhibits ...excellent activity for both UOR and HER.•DUFC with CA-Ni5P4@NiOx/NF as anode could reach as power output of 3.4 mW/cm2.
The electrochemical urea oxidation (UOR) involves the generation of gases bubbles, which often cause the blockage of the electrode surface leading to decline activity. Herein, we report the growth of Ni5P4 nanosheets on nickel foam as bifunctional electrode (CA-Ni5P4@NiOx/NF) for urea electrolysis. The results indicated that a thin layer of amorphous NiOx formed on the surface of Ni5P4 nanosheets to yield a unique crystalline@amorphous core–shell structure, which can be maintained during long time urea electrolysis. The outstanding UOR performance of CA-Ni5P4@NiOx/NF was attributed to the unique structure, which not only combine the good conductivity and abundant active sites, but also rendered the CA-Ni5P4@NiOx/NF superhydrophilic and aerophobic that significantly facilities the release of gases bubbles formed during UOR to avoid the blockage of the active sites. As a result, the CA-Ni5P4@NiOx/NF electrode exhibited excellent performance for UOR, which only needs 1.45 V (vs. RHE) to deliver a current of 100 mA/cm2. When used as anode for direct urea fuel cell (DUFC), it could reach a maximal power density as high as 3.4 mW/cm2with an OCV of 0.76 V. The CA-Ni5P4@NiOx/NF also exhibited excellent activity for hydrogen evolution reaction (HER), with -0.089 V (vs. RHE) to deliver a current of 10 mA/cm2. The electrolyzer constructed with CA-Ni5P4@NiOx as both anode and cathode could run for more than 10 h at a high current load about 100 mA/cm2 without appreciable potential change, indicating the superb stability of the CA-Ni5P4@NiOx electrode. Our work provides new insights for understanding as well as the development of advanced electrode for DUFC and urea electrolysis.
Urea cycle disorders-update Matsumoto, Shirou; Häberle, Johannes; Kido, Jun ...
Journal of human genetics,
09/2019, Letnik:
64, Številka:
9
Journal Article
Recenzirano
The urea cycle is a metabolic pathway for the disposal of excess nitrogen, which arises primarily as ammonia. Nitrogen is essential for growth and life-maintenance, but excessive ammonia leads to ...life-threatening conditions. The urea cycle disorders (UCDs) comprise diseases presenting with hyperammonemia that arise in either the neonatal period (about 50% of cases) or later. Congenital defects of the enzymes or transporters of the urea cycle cause the disease. This cycle utilizes five enzymes, two of which, carbamoylphosphate synthetase 1 and ornithine transcarbamylase are present in the mitochondrial matrix, whereas the others (argininosuccinate synthetase, argininosuccinate lyase and arginase 1) are present in the cytoplasm. In addition, N-acetylglutamate synthase and at least two transporter proteins are essential to urea cycle function. Severity and age of onset depend on residual enzyme or transporter function and are related to the respective gene mutations. The strategy for therapy is to prevent the irreversible toxicity of high-ammonia exposure to the brain. The pathogenesis and natural course are poorly understood because of the rarity of the disease, so an international registry system and novel clinical trials are much needed. We review here the current concepts of the pathogenesis, diagnostics, including genetics and treatment of UCDs.
Morphine is an alkaloid from the opium poppy used to treat pain. The potentially lethal side effects of morphine and related opioids-which include fatal respiratory depression-are thought to be ...mediated by μ-opioid-receptor (μOR) signalling through the β-arrestin pathway or by actions at other receptors. Conversely, G-protein μOR signalling is thought to confer analgesia. Here we computationally dock over 3 million molecules against the μOR structure and identify new scaffolds unrelated to known opioids. Structure-based optimization yields PZM21-a potent G
activator with exceptional selectivity for μOR and minimal β-arrestin-2 recruitment. Unlike morphine, PZM21 is more efficacious for the affective component of analgesia versus the reflexive component and is devoid of both respiratory depression and morphine-like reinforcing activity in mice at equi-analgesic doses. PZM21 thus serves as both a probe to disentangle μOR signalling and a therapeutic lead that is devoid of many of the side effects of current opioids.
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