Injections Of Urea Research Articles

Ammonia Slip Estimation Based on Ammonia Slip Catalyst Control-Oriented Modeling and On-Board Diagnostics NOX Sensor Cross-Sensitivity Analysis

Abstract The incoming emission regulations for internal combustion engines are gradually introducing new pollutant species, which require greater complexity of the aftertreatment systems concerning layout, control, and diagnostics. This is the case of ammonia, which is injected into the exhaust gas through urea injections for NOx abatement in selective catalytic reduction (SCR) systems and can also be generated in three-way catalysts. However, ammonia slip requires its oxidation on a dedicated ammonia slip catalyst (ASC). The set composed of the urea injection system, SCR, and ASC requires control tools to ensure high NOx conversion efficiency and compliant ammonia slip under real driving conditions. These tasks are based on the use of NOx sensors ZrO2 pumping cell-based, which has the disadvantage of high cross-sensitivity to ammonia that can affect the measurement of NOx and compromise the SCR-ASC control strategies. The present work proposes a methodology to predict ammonia and NOx tailpipe emissions. For this purpose, a control-oriented ASC model was developed to use its ammonia slip prediction to determine the cross-sensitivity correction of the tailpipe NOx sensor. The model is based on a simplified solution of the transport equations of the species involved in the ASC reaction mechanism. The model was calibrated using steady- and quasi-steady-state tests performed in a Euro 6c engine. Finally, the performance of the proposed methodology to predict NOx and ammonia emissions was evaluated against experimental data corresponding to worldwide harmonized light vehicles test cycles (WLTC) applying different urea dosing strategies.

An Experimental Study on the Characteristics of NOx Distributions at the SNCR Inlets of a Large-Scale CFB Boiler

The unknown NOx distributions inside large-scale CFB (circulating fluidized bed) boilers have always hindered the economy of the SNCR (selective non-catalytic reduction) process. In this study, field tests were carried out on a typical 300 MW CFB boiler, where multi-level 316 L-made probe and Ecom-J2KN/Testo 350 analyzers were used to perform detailed two-dimensional distributions of flue gas composition at SNCR inlets for the first time. The penetration depth inside the horizontal flue pass was up to 7 m. The NOx distributions were analyzed in detail combining with the auxiliary test in the dilute phase zone. Key results show that the average O2 concentrations in #A and #C regions were 6.52% and 0.95%, respectively. The vertical NOx distributions of #A and #C SNCR inlets were similar, showing a trend of first increasing and then decreasing with peak value all appeared at 5 m depth, while the NOx distribution of #B SNCR inlet was basically increasing. Some local areas with extremely high NOx concentration (over 2000 mg/m3) were observed near the inclined edge of SNCR inlets, which has never been reported before. Based on this, the optimization of urea injections was conducted, which could save 15.7% of the urea solution consumption while ensuring ultra-low emission of NOx.

A High Protein Model Alters the Endometrial Transcriptome of Mares.

High blood urea nitrogen (BUN) decreases fertility of several mammals; however, the mechanisms have not been investigated in mares. We developed an experimental model to elevate BUN, with urea and control treatments (7 mares/treatment), in a crossover design. Urea-treatment consisted of a loading dose of urea (0.03 g/kg of body weight (BW)) and urea injections over 6 h (0.03 g/kg of BW/h). Control mares received the same volume of saline solution. Blood samples were collected to measure BUN. Uterine and vaginal pH were evaluated after the last intravenous infusion, then endometrial biopsies were collected for RNA-sequencing with a HiSeq 4000. Cuffdiff (2.2.1) was used to identify the differentially expressed genes (DEG) between urea and control groups (false discovery rate-adjusted p-value < 0.1). There was a significant increase in BUN and a decrease of uterine pH in the urea group compared to the control group. A total of 193 genes were DEG between the urea and control groups, with five genes identified as upstream regulators (ETV4, EGF, EHF, IRS2, and SGK1). The DEG were predicted to be related to cell pH, ion homeostasis, changes in epithelial tissue, and solute carriers. Changes in gene expression reveal alterations in endometrial function that could be associated with adverse effects on fertility of mares.

تدوير المخلفات الزراعية النباتية بمحافظة الدقهلية " دراسة في جغرافية الصناعة "

Study in the Geography of Industry Summary The waste plant in Dakahlia governorate and most other governorates of the wealth is not fully exploited and represent the quantities in Dakahlia 13% of the total quantities in the Republic. The importance of recycling is due to its availability as its value evolves and the environment is conserved. Recycling is concentrated in organic fertilizers by composting and animal feed by mechanical, chemical, biological and silage. Waste is generated in all centers of the governorate, but its circulation is concentrated in only 8 centers with a prevalence index of 47%, most notably Belqas . The recycling rate was 26.5% in 2017 of the total waste in the study area . The investment in recycling operations yields a good return in a limited period of up to 59.1% . Recycling products are marketed to farmers within Dakahlia , owners of large animal husbandry farms, and the Ministry of the Environment. The recycling industry in the governorate faces obstacles such as high transport costs, ammonia and urea injections, limited recycling and storage areas, and lack of experience . Therefore, The role of agro-industrialization should be activated , Providing equipment for recycling , the operation of existing plants at full capacity, the creation of more of them, the intensification of extension courses and the provision of loans.

Detecting Microbially Induced Calcite Precipitation in a Model Well-Bore Using Downhole Low-Field NMR.

Microbially induced calcite precipitation (MICP) has been widely researched recently due to its relevance for subsurface engineering applications including sealing leakage pathways and permeability modification. These applications of MICP are inherently difficult to monitor nondestructively in time and space. Nuclear magnetic resonance (NMR) can characterize the pore size distributions, porosity, and permeability of subsurface formations. This investigation used a low-field NMR well-logging probe to monitor MICP in a sand-filled bioreactor, measuring NMR signal amplitude and T2 relaxation over an 8 day experimental period. Following inoculation with the ureolytic bacteria, Sporosarcina pasteurii, and pulsed injections of urea and calcium substrate, the NMR measured water content in the reactor decreased to 76% of its initial value. T2 relaxation distributions bifurcated from a single mode centered about approximately 650 ms into a fast decaying population (T2 less than 10 ms) and a larger population with T2 greater than 1000 ms. The combination of changes in pore volume and surface minerology accounts for the changes in the T2 distributions. Destructive sampling confirmed final porosity was approximately 88% of the original value. These results indicate the low-field NMR well-logging probe is sensitive to the physical and chemical changes caused by MICP in a laboratory bioreactor.

Development of MIP sensor for monitoring propofol in clinical procedures

Propofol is a widely used intravenous anaesthetic which requires close patient monitoring that involves blood extraction methods. Polymers with high affinity for propofol were computationally designed and their binding affinity tested. A diethylaminoethyl methacrylate based molecularly imprinted polymer was optimised in solid-phase extraction experiments showing no cross-reactivity to injections of urea, glucose, alfentanil and morphine. These polymers were initially integrated with screen-printed electrodes by photopolymerisation and used to detect propofol amperometrically, before modification to include conductive carbon to create better communication between the recognition sites of the polymer and the electrode. The sensors exhibited excellent linearity across the relevant clinical range with a detection limit of 4.19 µM measured in the presence of highly electroactive interferents such as uric acid and ascorbic acid. The mode of operation of the sensor reported herein differs significantly from the current state of the art and opens new opportunity towards the integration of synthetic receptors as electrochemical biosensors for point-of-care applications.

Ammonia and urea excretion in the Pacific hagfish Eptatretus stoutii: Evidence for the involvement of Rh and UT proteins

The nature of ammonia and urea excretion was examined in the Pacific hagfish ( Eptatretus stoutii), which, under resting conditions, excreted similar quantities of nitrogen as either ammonia or urea. In the presence of high external ammonia (HEA) concentrations, ammonia was taken up at high rates and then excreted at similarly high rates upon return to normal water. However, although elevated by HEA, plasma ammonia levels were maintained at approximately 1–4 μmol N g − 1 , reflecting time-dependent decreases in the rates of ammonia uptake, the possible conversion of ammonia to urea, and the potential active excretion of ammonia against a gradient. Internal injections of NH 4Cl caused marked increases in the rate of ammonia excretion and a delayed increase in urea excretion that may have resulted from increasing urea levels in the plasma. Conversely, when the rate of urea excretion was reduced in the presence of 0.1 mM phloretin, ammonia excretion was significantly elevated. Rates of urea excretion were initially increased by approximately 1000-fold following internal urea injections while the presence of high external urea levels (5–100 mM final concentration) resulted in associated linear increases in plasma urea levels. Using hagfish skin mounted in Ussing chambers, the rate of diffusion of ammonia across the skin exceeded that of urea by approximately four times when equivalent gradients were imposed. Based on western blotting and immunocytochemistry, hagfish gill appears to possess Rh proteins (Rhag, Rhbg and Rhcg1) and urea transporter proteins. Despite the tolerance of hagfish to high levels of ammonia and urea, it is suggested that the presence of ammonia and urea transporter proteins may be required during the period of time hagfish spend in burrows or while feeding, when conditions of high ammonia and/or urea might be encountered.

ARE UREA AND CREATININE UREMIC TOXINS IN THE RAT?

Urea and creatinine are not generally considered to be important uremic toxins despite evidence from dialysis experiments to the contrary, and despite striking elevations of these nitrogenous waste products in uremia. In order to study this problem in acute uremia, we used a new dietary method for prolonging the survival of bilaterally nephrectomized rats. Urea or creatinine were injected on three successive days starting one day after the inception of uremia. Urea or creatinine injections shortened the survival time of acutely uremic rats, and increased the involution of thymus and spleen. The extra urea, but not creatinine, increased the serum osmolality. These data indicate that urea and creatinine are toxic in the acutely uremic rat. Hypertonicity of the serum may contribute to the toxicity of urea. Additional mechanisms of toxicity and additional toxins are not excluded.

Lithium treatment for bipolar disorder.

Psychiatry is a relative newcomer to the pantheon of medical specialties. While this discipline possesses a venerable heritage of keen observation and description -- as exemplified by the writings of Burton (1), Pinel (2) and Kraepelin (3) -- the pathophysiological processes underlying the "functional" psychoses such as schizophrenia and bipolar disorder (manic-depressive illness) still remain elusive. However, despite the lack of understanding about the etiological processes involved, major advances in treatment were achieved in the 20th century. Prominent among these was John Cade's discovery of lithium's effectiveness in the treatment of mania (4-6). At the time of his discovery, John Cade was a 37-year-old medical officer working in a war veterans' repatriation hospital for chronic psychiatric illnesses, in an outer suburb of Melbourne, Australia. The son of a psychiatrist, who had himself suffered from depression, Cade had recently returned from three years' incarceration in the Changi prisoner-of-war camp in Singapore. There he had found that all of his patients with psychiatric illness who had died (and were examined post mortem) had some significant pathology, such as a tumour. This observation impressed upon him the strong likelihood of an underlying physical cause for manic-depressive illness, particularly as he saw no apparent relationship between stress and psychiatric presentations in the camp (7). In 1947, Cade wrote of his hypothesis that "manic-depressive insanity" was analogous to states of hyper- and hypothyroidism, with mania being "a state of intoxication of a normal product of the body circulating in excess", while "melancholia is the corresponding deprivative condition" (8). With the limited investigative techniques of the day -- his laboratory was a converted wooden shed in the grounds of the hospital -- he began to search for the hypothesized "toxic agent" in the urine of manic patients. The fact that he was undertaking animal studies in a psychiatric hospital in the 1940s is remarkable in itself. To examine for the pharmacological effect in animals of any such toxin, he injected guinea-pigs intraperitoneally with the urine of patients with mania, schizophrenia and melancholia, as well as that of normal subjects. He found that the urine of manic patients was particularly toxic, animals being killed by much lower amounts than by urine from patients with other disorders. Cade then injected the animals with pure forms of the main nitrogenous constituents of urine to identify the specific lethal compound. He found that injections of urea led to exactly the same mode of death as observed with whole urine. He was, however, unable to explain the greater toxicity of the urine of manic patients in terms of higher concentrations of urea. Thus, he began to search for substances that could modify the toxic effect of urea, either by diminution or by enhancement. Cade noted in his 1947 article that uric acid appeared to have a "slightly enhancing" effect on the toxicity of urea. His 1949 paper (4), reproduced here, described the fruition of the research presaged in his earlier work. He had continued the search for the postulated compound that enhanced the toxicity of urea. Further study of uric acid was difficult, though, as it was relatively insoluble in water. To overcome this problem, he fortuitously chose lithium urate, the most soluble of the urates. To Cade's surprise, when he injected the guinea-pigs with lithium urate in conjunction with urea, the toxicity was reduced rather than enhanced, suggesting that the lithium may have been protective. Cade further explored this lead by injecting the guinea-pigs with lithium carbonate in conjunction with urea, and once more observed reduced toxicity. He concluded that lithium itself provided a protective effect against the action of urea. This belief then caused him to wonder whether lithium per se would have an effect on his guinea-pigs. …

Concentration thresholds for fetal swallowing and vasopressin secretion.

In adults, plasma osmolality thresholds for hypernatremia-induced arginine vasopressin (AVP) secretion are similar or less than thresholds for stimulation of thirst. In the fetus, the thresholds for swallowing stimulation and AVP secretion have not been defined. Fetal swallowing and AVP secretory responses to hypertonic NaCl and urea were determined in six fetuses (130 +/- 1 1 days) chronically prepared with thyrohyoid, nuchal and thoracic esophagus, and diaphragm electromyograms (EMG), an esophageal flow probe, and vascular catheters. Fetuses received intracarotid injections (0.15 ml/kg) of increasing concentrations of NaCl (0.15, 0.30, 0.45, 0.60, 0.75, and 0.90 M), administered at 2-min intervals. A swallow was defined as a coordinated time-sequence of fetal thyrohyoid, nuchal esophagus, and thoracic esophagus EMG activity. The threshold saline concentration for swallowing was defined as the minimum NaCl dose eliciting swallow responses (within 20 s) after four of five injections at each dose. During a 2-h control period swallowing averaged 25.0 +/- 10.1 ml/h and 39.4 +/- 14.6 swallows/h. The mean NaCl threshold concentration for swallowing stimulation was 0.56 +/- 0.06 M. Fetal plasma AVP (2.6 +/- 0.9 pg/ml) increased significantly at the maximum subthreshold (7.6 +/- 4.0 pg/ml) and the threshold NaCl concentration (8.2 +/- 4.0 pg/ml) that stimulated swallowing. On a subsequent day, equiosmolar urea injections increased plasma AVP (from 2.2 +/- 0.7 to 7.6 +/- 2.6 pg/ml) but had no effect on swallowing activity. Fetal mean arterial blood pressure increased after injections of threshold saline and urea concentrations. Fetal arterial blood osmolality and sodium concentration did not change during any study.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphologic effects of glycerol and urea on cochlear tissues of the chinchilla.

Glycerol and urea are used as test agents in confirming the diagnosis of endolymphatic hydrops. Although both substances act as osmotic diuretics, recent evidence suggests that they may have differing physiologic effects on the inner ear. This study was designed to compare the morphologic effects of urea and glycerol on cochlear tissues, using the chinchilla as an experimental model. Animals were given subcutaneous injections of glycerol (2 g/kg) or urea (1.2 g/kg) over periods of 3 hours, 4 days, or 1 week. Both agents were found to produce ultrastructural changes, including spiral ligament vacuolization, intracellular alterations of the stria vascularis, and increased numbers of Hensen's bodies in outer hair cells. These alterations appeared indicative of metabolic stress, but not toxicity. The morphologic findings provided no evidence that glycerol and urea affect the inner ear by fundamentally different mechanisms of action.

Untersuchungen zum Einfluß von 2-Cyanäthylharnstoff Thymus-Extrakt und Lithiumkarbonat auf die Leukozytenzahl im peripheren Blut nach Ganzkörperbestrahlung

In our investigations the qualification of the substances 2-cyanoethyl urea, thymus extract and lithium carbonate was tested for a potential reducing or shortening of the leukocyte-depression in rats after whole-body irradiation. Intravenous applications of 2-cyanoethyl urea and intramuscular injections of thymus extract showed no effect in Wistar rats not only in increase of leukocyte number of peripheral blood, but also in variation of leukocyte portion in differential blood-count. Leukocytes depression appearing in consequence of whole-body irradiation was independent of cyanoethyl urea applications and of thymus extract, too. Lithium carbonate shows a significant increase of leukocytes in peripheral blood in dependence of dosage and frequency of applications. After whole-body irradiation with 7 Gy under lithium therapy, it was shown that on day 6 after irradiation leukocyte number was significantly higher than in controls. Radiogenic leukopenia phase was reduced significantly by lithium.

Urea-induced myoclonus: Medullary glycine antagonism as mechanism of action

Stimulus sensitive myoclonus is a prominent symptom of uremia in both man and animals. Intravenous injection of urea into cats had been previously reported to produce spike and sharp wave electrical discharges in the medullary reticular formation which correlated with the myoclonic movements. In the present investigations, intraperitoneal injections of 2 g/kg urea every 15 minutes for 4 injections produced myoclonus in rats accompanied by brain urea concentrations of 6.8 × 10 −2M, whic is sevenfold higher than normal. 10 −2 and 10 −1M urea significantly reduced 3H-strychnine binding to rat medulla membranes by 30% and 43% respectively. Urea inhibition of 3H-strychnine binding was reversible and binding kinetics revealed that 10 −1M urea decreased Bmax by 65% with no effect on the affinity. Brain glycine levels did not change after urea injections and urea had no effect on syhaptosomal uptake of 3H-glycine. Urea did not alter 3H-GABA, 3H-glutamate and 3H-QNB receptor binding but decreased 3H-diazepam receptor binding in the medulla. Mannitol also reduced 3H-diazepam binding but had no effect on 3H- strychnine binding. Stereotaxic injection of the glycine receptor antagonist, strychnine, into the rat medullary reticular formation produced myoclonus, whereas Ro 15–1788, a benzodiazepine antagonist, had no effect. Urea may produce myoclonus by blockade of glycine receptors in the medullary reticular formation.

Protection by dimethyl urea against hyperglycaemia, but not insulitis, in low-dose streptozotocin-induced diabetes in the mouse.

The protective effect of dimethyl urea, a hydroxyl radical scavenger, against low-dose streptozotocin-induced diabetes has been evaluated. Dimethyl urea was given to C57BL/KsJ mice before five daily injections of streptozotocin. The saline pre-treated control animals became gradually hyperglycaemic, whereas the dimethyl urea treated group remained normoglycaemic during the 11 week follow-up period. Two weeks after the first streptozotocin injection, six out of ten dimethyl urea-treated and 12 out of 15 saline-treated mice had insulitis. Four or 11 weeks after the streptozotocin treatment, insulitis was rare in both groups. Multiple injections of dimethyl urea only did not affect the serum glucose concentrations or the islet morphology. It is suggested that dimethyl urea protected against hyperglycaemia by reducing the beta-cell cytotoxic effects of the low doses of streptozotocin. An increased number of cells would thus be preserved and the animals less prone to develop diabetes, despite the presence of an inflammatory process in the pancreatic gland.

The effects of urea treatment in combination with curettage in extensive lip cancers.

Thirty cases of lip cancer in 28 patients, 23 of which were extensive or very extensive, were treated with local urea injections in combination with curettage. Out of the 30 cases there were 26 squamous cell carcinomas, three basal cell carcinomas extending to the mucosa from the skin of the lips, and one adenocarcinoma of the mucosa of the interior surface of the upper lip. This treatment was effective in all our patients. Recurrences appeared in four patients. These were easily treated in three out of the four patients who returned for treatment, by the same method. In three cases metastases appeared in the lymphnodes of the neck, which were surgically treated.

Changes in the neurosecretory cells of the freshwater snail, lymnaea acuminata induced by urea administration

The effect of urea injections on the cytomorphology of neurosecretory cells of the snail L. acuminata has been examined. Of the three types of neurosecretory cells (A, B and C) the changes were evident only in C cells from the parietal ganglia. 3 hr after 0.1 ml of 1 M urea plus 0.1 ml of I M glucose injection, the appearance of neurosecretory material (NSM) in the neurohaemal area without any change in C cell C : N (Cytoplasm: nuclear) ratio, was evident, whereas daily injection of urea plus glucose for three consecutive days induced a significant (P = 0.005) increment in C cell nuclear diameter and C : N value over equiosmole control (glucose) injections. This was accompanied by about 50% depletion of perikarya NSM intensity and the neurohaemal area was completely destitute of the NSM. The significance of the data is discussed.

Effect of transitory hyperuremia on LDH levels in selected marine elasmobranchs and chimaeras: An apparent urea requirement

1. 1. Urea and lactic dehydrogenase (rate reaction) levels were assayed in nervous system associated fluids and several relevant tissues in selected, mostly primitive, marine fishes both in vivo and in vitro at varying times subsequent to single injections of supplemental urea. 2. 2. Serum clearance times were generally more rapid for most teleosts than the more primitive elasmobranchs and chimaeras. Depletion patterns are compared in various species. 3. 3. The highest urea levels were observed in ratfish extra-brain fluid, and coelacanth ventricular fluid. 4. 4. LDH was detectable in “old” frozen coelacanth fluids. LDH levels were relatively high in elasmobranchs, chimaeras and salmon brain-associated fluids. 5. 5. Tolerance of supplemental urea, based on LDH levels after the addition of supplemental urea was the most, absolutely, in S. acanthias and H. colliei, and high proportionally in the salmon and sole in the fluids studied. 6. 6. The implications of these enzyme level “enhancements” are discussed both in view of primitive fish physiology, and the relevance to human physiological disease processes and certain current therapeutic practices.

Structural Alterations in the Ciliary Process and the Blood-Aqueous Barrier of the Monkey after Systemic Urea Injections

The structural alterations induced in the monkey ciliary epithelium by intravascular injection of urea solutions were studied with the light and electron microscopes. Arterial injection of urea resulted in destruction of the nonpigmented epithelium and the consequent breakdown of the blood-aqueous barrier. The intravenous injection did not significantly affect the structural integrity of the ciliary epithelium. The intercellular zonulae occludens were not altered and the intercellular pathway from blood to posterior chamber remained closed to horseradish peroxidase. Intercellular uptake in large cytoplasmic vacuoles appeared to account for some late transport to the basal end of the nonpigmented epithelium. There was no comparable transport of peroxidase in vesicles or vacuoles through the nonpigmented epithelium in animals not subjected to intravenous urea treatment. Compared to the arterial route, intravenous administration of urea does not appear to pose a serious threat to the integrity of the ciliary epithelium.

Urea treatment of skin malignancies

Abstract 112 patients with basal or squamous cell skin carcinomas were treated with urea. During the first 2 years treatment consisted in injections of urea solution around the lesion, and 73 % of patients definitely benefited. In the third year treatment was modified by combining injections of urea with scraping off and treatment of the traumatised surface with urea powder. In this way definitive benefit reached 91%. Despite very good results with the conventional therapeuthic methods urea treatment is thought to be valuable because of its simplicity, superior cosmetic results, and absence of side-effects. These advantages make it especially useful in cases of carcinomas of the eyelids, canthi, nose and ears.

Nitrogen metabolism in the ovine stomach: 3. Urea in the abomasal secretions

SUMMARYThe effects of various stimuli on the secretion of urea and ammonia in gastric juice were examined in sheep with innervated pouches in the fundic and pyloric regions of the abomasum.Histamine, pentagastrin and feeding increased the rate of secretion and acidity of fundic juice, but had little or no effect on the concentration of urea and ammonia. The increased output of gastric juice meant that more urea and ammonia entered the abomasum in the secretions. The rate of secretion of pyloric juice was also increased by histamine and feeding, and there was an indication that histamine increased the concentration of urea + ammonia in the secretions after a period of starvation.Intravenous injections of urea increased the concentration of ammonia in abomasal liquor. This was due in part to higher levels of ammonia in ruminal liquor passing to the abomasum, and to higher concentrations of urea + ammonia in gastric juice. The concentration of urea + ammonia in fundic juice was 45·0±1·1% of the plasma urea level, and 60·4±1·5% in the pyloric secretions.