Modeling of fireside deposit formation in two industrial furnaces

Fireside deposits can be found in many types of utility and industrial furnaces. The deposits in furnaces are problematic because they can reduce heat transfer, block gas paths and cause corrosion. To tackle these problems, it is vital to estimate the influence of deposits on heat transfer, to minimize deposit formation and to optimize deposit removal. It is beneficial to have a good understanding of the mechanisms of fireside deposit formation. Numerical modeling is a powerful tool for investigating the heat transfer in furnaces, and it can provide valuable information for understanding the mechanisms of deposit formation. In addition, a sub-model of deposit formation is generally an essential part of a comprehensive furnace model. This work investigates two specific processes of fireside deposit formation in two industrial furnaces. The first process is the slagging wall found in furnaces with molten deposits running on the wall. A slagging wall model is developed to take into account the two-layer structure of the deposits. With the slagging wall model, the thickness and the surface temperature of the molten deposit layer can be calculated. The slagging wall model is used to predict the surface temperature and the heat transfer to a specific section of a super-heater tube panel with the boundary condition obtained from a Kraft recovery furnace model. The slagging wall model is also incorporated into the computational fluid dynamics (CFD)-based Kraft recovery furnace model and applied on the lower furnace walls. The implementation of the slagging wall model includes a grid simplification scheme. The wall surface temperature calculated with the slagging wall model is used as the heat transfer boundary condition. Simulation of a Kraft recovery furnace is performed, and it is compared with two other cases and measurements. In the two other cases, a uniform wall surface temperature and a wall surface temperature calculated with a char bed burning model are used as the heat transfer boundary conditions. In this particular furnace, the wall surface temperatures from the three cases are similar and are in the correct range of the measurements. Nevertheless, the wall surface temperature profiles with the slagging wall model and the char bed burning model are different because the deposits are represented differently in the two models. In addition, the slagging wall model is proven to be computationally efficient. The second process is deposit formation due to thermophoresis of fine particles to the heat transfer surface. This process is considered in the simulation of a heat recovery boiler of the flash smelting process. In order to determine if the small dust particles stay on the wall, a criterion based on the analysis of forces acting on the particle is applied. Time-dependent simulation of deposit formation in the heat recovery boiler is carried out and the influence of deposits on heat transfer is investigated. The locations prone to deposit formation are also identified in the heat recovery boiler. Modeling of the two processes in the two industrial furnaces enhances the overall understanding of the processes. The sub-models developed in this work can be applied in other similar deposit formation processes with carefully-defined boundary conditions.

Potential for seed bank formation of two weed species from Brazilian Amazonia

The potential for seed bank formation of two perennial weed species, Ipomoea asarifolia (Desr.) Roem. & Schult. (Convolvulaceae) and Stachytarpheta cayennensis (Rich.) M. Vahl (Verbenaceae), both common in Amazonia , was evaluated in a degraded pasture area in eastern Brazilian Amazonia . Seeds were enclosed in nylon mesh packets and placed at the soil surface or buried at 5 or 10 cm deep. The number of viable seeds was recorded at 6, 10, 14 and 18 months after burial. Results showed that S. cayennensis has the ability to form persistent soil seed bank, while I. asarifolia seeds do not build up in the soil seed bank. For S. cayennensis and, to some extent, for I. asarifolia, seed survival was highest at greater burial depths.

Determinants of Polylepis (Rosaceae) Forest Distribution and Treeline Formation in the High Andes

High elevation treelines are formed under common temperature conditions worldwide, but the functional mechanisms that ultimately constrain tree growth are poorly known. In addition to environmental constraints, the distribution of high elevation forests is largely affected by human influence. Andean Polylepis (Rosaceae) forests are an example of such a case, forests commonly growing in isolated stands disconnected from the lower elevation montane forests. There has been ample discussion as to the role of environmental versus anthropogenic causes of this fragmented distribution of Polylepis forests, but the importance of different factors is still unclear. In this thesis, I studied functional, environmental and anthropogenic aspects determining Polylepis forest distribution. Specifically, I assessed the degree of genetic determinism in the functional traits that enable Polylepis species to grow in cold and dry conditions. I also studied the role of environment and human influence constraining Polylepis forest distribution. I found evidence of genetically determined climatic adaptations in the functional traits of Polylepis. High elevation species had reduced leaf size and increased root tip abundance compared to low elevation species. Thus these traits have potentially played an important role in species evolution and adaptation to high elevation habitats, especially to low temperatures. I also found reduced photosynthesis rate among high elevation tree species compared to low elevation species, supporting carbon source limitation at treelines. At low elevations, Polylepis forest distribution appeared to be largely defined by human influence. This suggests that the absence of Polylepis forests in large areas in the Andes is the result of several environmental and anthropogenic constraints, the role of environment becoming stronger towards high elevations. I also show that Polylepis trees grow at remarkably low air and soil temperatures near treelines, and present new evidence of the role of air temperatures in constraining tree growth at high elevations. I further show that easily measurable indices of accessibility are related to the degree of degradation of Polylepis forest, and can therefore be used in the rapid identification of potentially degraded Polylepis forests. This is of great importance for the conservation and restoration planning of Polylepis forests in the Andes. In a global context, the results of this thesis add to our scientific knowledge concerning high elevation adaptations in trees, and increase our understanding of the factors constraining tree growth and forest distribution at high-­elevation treelines worldwide.

Oxalic acid and calcium oxalate in production of wood-containing paper : formation, analysis, and control

Papperstillverkningen störs ofta av oönskade föreningar som kan bilda avsättningar på processytor, vilket i sin tur kan ge upphov till störningar i pappersproduktionen samt försämring av papperskvaliteten. Förutom avsättningar av vedharts är stenliknande avlagringar av svårlösliga salter vanliga. I vårt dagliga liv är kalkavlagringar i kaffe- och vattenkokare exempel på liknande problem. I massa- och pappersindustrin är en av de mest problematiska föreningarna kalciumoxalat; detta salt är nästan olösligt i vatten och avlagringarna är mycket svåra att avlägsna. Kalciumoxalat är också känt som en av orsakerna till njurstenar hos människor. Veden och speciellt barken innehåller alltid en viss mängd oxalat men en större källa är oxalsyra som bildas när massan bleks med oxiderande kemikalier, t.ex. väteperoxid. Kalciumoxalat bildas när oxalsyran reagerar med kalcium som kommer in i processen med råvattnet, veden eller olika tillsatsmedel. I denna avhandling undersöktes faktorer som påverkar bildningen av oxalsyra och utfällningen av kalciumoxalat, med hjälp av bleknings- och utfällningsexperiment. Forskningens fokus låg speciellt på olika sätt att förebygga uppkomsten av avlagringar vid tillverkning av trähaltigt papper. Resultaten i denna avhandling visar att bildningen av oxalsyra samt utfällning av kalciumoxalat kan påverkas genom processtekniska och våtändskemiska metoder. Noggrann avbarkning av veden, kontrollerade förhållanden under den alkaliska peroxidblekningen, noggrann hantering och kontroll av andra lösta och kolloidala substanser, samt utnyttjande av skräddarsydd kemi för kontroll av avlagringar är nyckelfaktorer. Resultaten kan utnyttjas då man planerar blekningssekvenser för olika massor samt för att lösa problem orsakade av kalciumoxalat. Forskningsmetoderna som användes i utfällningsstudierna samt för utvärdering av tillsatsmedel kan också utnyttjas inom andra områden, t.ex. bryggeri- och sockerindustrin, där kalciumoxalatproblem är vanligt förekommande. -------------------------------------------- Paperinvalmistusta häiritsevät usein erilaiset epäpuhtaudet, jotka kiinnittyvät prosessipinnoille ja haittaavat tuotantoa sekä paperin laatua. Puun pihkan lisäksi eräs yleinen ongelma on niukkaliukoisten suolojen aiheuttamat kivettymät. Kalkkisaostuma kahvinkeittimessä on esimerkki vastaavasta ongelmasta arkielämässä. Massa- ja paperiteollisuudessa yksi hankalimmista kivettymien muodostajista on kalsiumoksalaatti, koska se on lähes liukenematonta ja sen aiheuttamat saostumat ovat erittäin vaikeasti poistettavia. Kalsiumoksalaatti on yleisesti tunnettu myös munuaiskivien aiheuttajana ihmisillä. Puu ja varsinkin sen kuori sisältää aina jonkin verran oksalaattia, mutta suurempi lähde on kuitenkin oksaalihappo jota muodostuu valkaistaessa massaa hapettavilla kemikaaleilla, kuten vetyperoksidilla. Kalsiumoksalaattia syntyy kun veden, puun ja lisäaineiden mukana prosessiin tuleva kalsium reagoi oksalaatin kanssa. Tässä väitöskirjatyössä tutkittiin oksaalihapon muodostumiseen ja kalsiumoksalaatin saostumiseen vaikuttavia tekijöitä valkaisu- ja saostumiskokeiden avulla. Tutkimuksen painopiste oli saostumien ehkäisemisessä puupitoisten painopaperien valmistuksessa. Työssä saadut tulokset osoittavat että oksaalihapon muodostumiseen ja kalsiumoksalaatin saostumiseen voidaan vaikuttaa sekä prosessiteknisten että märänpään kemian keinojen avulla. Tehokas puun kuorinta, optimoidut olosuhteet peroksidivalkaisussa, muiden liuenneiden ja kolloidisten aineiden hallinta sekä räätälöidyn kemian hyödyntäminen kalsiumoksalaattisaostumien torjunnassa ovat keskeisissä rooleissa ongelmien välttämiseksi. Väitöskirjatyön tuloksia voidaan hyödyntää massan valkaisulinjoja suunniteltaessa sekä kalsiumoksalaatin aiheuttamien ongelmien ratkaisemisessa. Tutkimusmenetelmiä, joita käytettiin saostumiskokeissa ja eri lisäaineiden vaikutusten arvioinnissa, voidaan hyödyntää massa- ja paperiteollisuuden lisäksi myös muilla alueilla, kuten sokeri- ja panimoteollisuudessa, joissa ongelma on myös yleinen.

Weed suppression in the formation of brachiarias under three sowing methods

The success of conservation systems such as no-till depends on adequate soil cover throughout the year, which is possible through the use of cover crops. For this purpose the species belonging to the genus Urochloa has stood out by virtue of its hardiness and tolerance to drought. Aiming ground cover for the no-till system, the objective was to evaluate the establishment of two species of the genus Urochloa, in three sowing methods, in the weed suppression and the sensitivity of these forages to glyphosate. The study design was a randomized block with a 2 x 3 x 3 factorial arrangement, in which factor A was composed of Urochloa ruziziensis and Urochloa hybrid CIAT 36087 cv. Mulato II, factor B was formed by sowing methods: sown without embedding, sown with light embedding and sown in rows, and factor C was composed of three doses of glyphosate (0.975, 1.625 and 2.275 kg ha-1 of acid equivalent). For determination of weed suppression, assessment of biomass yield and soil cover was performed, by brachiaria and weeds, at 30, 60, 90, 120 and 258 days after sowing. Visual assessment of the desiccation efficiency at 7 and 14 days after herbicide application was performed. It is concluded that embedding Urochloa seeds stands out in relation to sowing in the soil surface. Urochloa ruziziensis is more efficient in the dry weight yield, weed suppression, in addition to being more sensitive to glyphosate herbicide.

Role of endothelium in angiotensin II formation by the rat aorta and mesenteric arterial bed

We investigated the angiotensin II (Ang II)-generating system by analyzing the vasoconstrictor effect of Ang II, angiotensin I (Ang I), and tetradecapeptide (TDP) renin substrate in the absence and presence of inhibitors of the renin-angiotensin system in isolated rat aortic rings and mesenteric arterial beds with and without functional endothelium. Ang II, Ang I, and TDP elicited a dose-dependent vasoconstrictor effect in both vascular preparations that was completely blocked by the Ang II receptor antagonist saralasin (50 nM). The angiotensin converting enzyme (ACE) inhibitor captopril (36 µM) completely inhibited the vasoconstrictor effect elicited by Ang I and TDP in aortic rings without affecting that of Ang II. In contrast, captopril (36 µM) significantly reduced (80-90%) the response to bolus injection of Ang I, without affecting those to Ang II and TDP in mesenteric arteries. Mechanical removal of the endothelium greatly potentiated (70-95%) the vasoconstrictor response to Ang II, Ang I, and TDP in aortic rings while these responses were unaffected by the removal of the endothelium of mesenteric arteries with sodium deoxycholate infusion. In addition, endothelium disruption did not change the pattern of response elicited by these peptides in the presence of captopril. These findings indicate that the endothelium may not be essential for Ang II formation in rat mesenteric arteries and aorta, but it may modulate the response to Ang II. Although Ang II formation from Ang I is essentially dependent on ACE in both vessels, our results suggest the existence of an alternative pathway in the mesenteric arterial bed that may play an important role in Ang II generation from TDP in resistance but not in large vessels during ACE inhibition

Behavior of black liquor nitrogen in combustion : formation of cyanate

The Kraft pulping process is the dominant chemical pulping process in the world. Roughly 195 million metric tons of black liquor are produced annually as a by-product from the Kraft pulping process. Black liquor consists of spent cooking chemicals and dissolved organics from the wood and can contain up to 0.15 wt% nitrogen on dry solids basis. The cooking chemicals from black liquor are recovered in a chemical recovery cycle. Water is evaporated in the first stage of the chemical recovery cycle, so the black liquor has a dry solids content of 65-85% prior to combustion. During combustion of black liquor, a portion of the black liquor nitrogen is volatilized, finally forming N2 or NO. The rest of the nitrogen remains in the char as char nitrogen. During char conversion, fixed carbon is burned off leaving the pulping chemicals as smelt, and the char nitrogen forms mostly smelt nitrogen (cyanate, OCN-). Smelt exits the recovery boiler and is dissolved in water. The cyanate from smelt decomposes in the presence of water, forming NH3, which causes nitrogen emissions from the rest of the chemical recovery cycle. This thesis had two focuses: firstly, to determine how the nitrogen chemistry in the recovery boiler is affected by modification of black liquor; and secondly, to find out what causes cyanate formation during thermal conversion, and which parameters affect cyanate formation and decomposition during thermal conversion of black liquor. The fate of added biosludge nitrogen in chemical recovery was determined in Paper I. The added biosludge increased the nitrogen content of black liquor. At the pulp mill, the added biosludge did not increase the NO formation in the recovery boiler, but instead increased the amount of cyanate in green liquor. The increased cyanate caused more NH3 formation, which increased the NCG boiler’s NO emissions. Laboratory-scale experiments showed an increase in both NO and cyanate formation after biosludge addition. Black liquor can be modified, for example by addition of a solid biomass to increase the energy density of black liquor, or by separation of lignin from black liquor by precipitation. The precipitated lignin can be utilized in the production of green chemicals or as a fuel. In Papers II and III, laboratory-scale experiments were conducted to determine the impact of black liquor modification on NO and cyanate formation. Removal of lignin from black liquor reduced the nitrogen content of the black liquor. In most cases NO and cyanate formation decreased with increasing lignin removal; the exception was NO formation from lignin lean soda liquors. The addition of biomass to black liquor resulted in a higher nitrogen content fuel mixture, due to the higher nitrogen content of biomass compared to black liquor. More NO and cyanate were formed from the fuel mixtures than from pure black liquor. The increased amount of formed cyanate led to the hypothesis that black liquor is catalytically active and converts a portion of the nitrogen in the mixed fuel to cyanate. The mechanism behind cyanate formation during thermal conversion of black liquor was not clear before this thesis. Paper IV studies the cyanate formation of alkali metal loaded fuels during gasification in a CO2 atmosphere. The salts K2CO3, Na2CO3, and K2SO4 all promoted char nitrogen to cyanate conversion during gasification, while KCl and CaCO3 did not. It is now assumed that cyanate is formed when alkali metal carbonate or an active intermediate of alkali metal carbonate (e.g. -CO2K) reacts with the char nitrogen forming cyanate. By testing different fuels (bark, peat, and coal), each of which had a different form of organic nitrogen, it was concluded that the form of organic nitrogen in char also has an impact on cyanate formation. Cyanate can be formed during pyrolysis of black liquor, but at temperatures 900°C or above, the formed cyanate will decompose. Cyanate formation in gasifying conditions with different levels of CO2 in the atmosphere was also studied. Most of the char nitrogen was converted to cyanate during gasification at 800-900°C in 13-50% CO2 in N2, and only 5% of the initial fuel nitrogen was converted to NO during char conversion. The formed smelt cyanate was stable at 800°C 13% CO2, while it decomposed at 900°C 13% CO2. The cyanate decomposition was faster at higher temperatures and in oxygen-containing atmospheres than in an inert atmosphere. The presence of CO2 in oxygencontaining atmospheres slowed down the decomposition of cyanate. This work will provide new information on how modification of black liquor affects the nitrogen chemistry during thermal conversion of black liquor and what causes cyanate formation during thermal conversion of black liquor. The formation and decomposition of cyanate was studied in order to provide new data, which would be useful in modeling of nitrogen chemistry in the recovery boiler.

Nonconventional amide bond formation catalysis: programming enzyme specificity with substrate mimetics

This article reports on the design and characteristics of substrate mimetics in protease-catalyzed reactions. Firstly, the basis of protease-catalyzed peptide synthesis and the general advantages of substrate mimetics over common acyl donor components are described. The binding behavior of these artificial substrates and the mechanism of catalysis are further discussed on the basis of hydrolysis, acyl transfer, protein-ligand docking, and molecular dynamics studies on the trypsin model. The general validity of the substrate mimetic concept is illustrated by the expansion of this strategy to trypsin-like, glutamic acid-specific, and hydrophobic amino acid-specific proteases. Finally, opportunities for the combination of the substrate mimetic strategy with the chemical solid-phase peptide synthesis and the use of substrate mimetics for non-peptide organic amide synthesis are presented.

Steps in the formation of neurites and synapses studied in cultured leech neurons

Leech neurons in culture have provided novel insights into the steps in the formation of neurite outgrowth patterns, target recognition and synapse formation. Identified adult neurons from the central nervous system of the leech can be removed individually and plated in culture under well-controlled conditions, where they retain their characteristic physiological properties, grow neurites and form specific chemical or electrical synapses. Different identified neurons develop distinctive outgrowth patterns that depend on their identities and on the molecular composition of the substrate. On native substrates, the patterns displayed by these neurons reproduce characteristics from the adult or the developing neurons. In addition, the substrate may induce selective directed growth between pairs of neurons that normally make contact in the ganglion. Upon contact, pairs of cultured leech neurons form chemical or electrical synapses, or both types depending on the neuronal identities. Anterograde and retrograde signals during membrane contact and synapse formation modify the distribution of synaptic terminals, calcium currents, and responses to 5-hydroxytryptamine.

Infusions of AP5 into the basolateral amygdala impair the formation, but not the expression, of step-down inhibitory avoidance

We evaluated the effects of infusions of the NMDA receptor antagonist D,L-2-amino-5-phosphonopentanoic acid (AP5) into the basolateral nucleus of the amygdala (BLA) on the formation and expression of memory for inhibitory avoidance. Adult male Wistar rats (215-300 g) were implanted under thionembutal anesthesia (30 mg/kg, ip) with 9.0-mm guide cannulae aimed 1.0 mm above the BLA. Bilateral infusions of AP5 (5.0 µg) were given 10 min prior to training, immediately after training, or 10 min prior to testing in a step-down inhibitory avoidance task (0.3 mA footshock, 24-h interval between training and the retention test session). Both pre- and post-training infusions of AP5 blocked retention test performance. When given prior to the test, AP5 did not affect retention. AP5 did not affect training performance, and a control experiment showed that the impairing effects were not due to alterations in footshock sensitivity. The results suggest that NMDA receptor activation in the BLA is involved in the formation, but not the expression, of memory for inhibitory avoidance in rats. However, the results do not necessarily imply that the role of NMDA receptors in the BLA is to mediate long-term storage of fear-motivated memory within the amygdala.

Role of ACTH receptor in adrenocortical tumor formation

Adrenocorticotrophin (ACTH) is the major regulatory hormone of steroid synthesis and secretion by adrenocortical cells. The actions of ACTH are mediated by its specific membrane receptor (ACTH-R). The human ACTH-R gene was recently cloned, allowing systematic determination of its sequence, expression and function in adrenal tumorigenesis. The presence of oncogenic mutations of the ACTH-R gene in adrenocortical tumors has been reported. Direct sequencing of the entire coding region of the ACTH-R gene of sporadic adrenocortical adenomas and carcinomas did not reveal constitutive activating mutations, indicating that this mechanism is not frequent in human adrenocortical tumorigenesis. Recent studies demonstrated allelic loss of the ACTH-R gene in a subset of sporadic adrenocortical tumors using a PstI polymorphism located in the promoter region of the ACTH-R gene. Loss of heterozygosity of the ACTH-R was analyzed in 20 informative patients with a variety of benign and malignant adrenocortical tumors. Three of them showed loss of heterozygosity of the ACTH-R gene. In addition, Northern blot experiments demonstrated reduced expression of ACTH-R mRNA in these three tumors with loss of heterozygosity, suggesting the functional significance of this finding at the transcriptional level. Deletion of the ACTH-R gene seems to be involved in a subset of human adrenocortical tumors, contributing to cellular dedifferentiation.

Fever induction pathways: evidence from responses to systemic or local cytokine formation

The immune and central nervous systems are functionally connected and interacting. The concept that the immune signaling to the brain which induces fever during infection and inflammation is mediated by circulating cytokines has been traditionally accepted. Administration of bacterial lipopolysaccharide (LPS) induces the appearance of a so-termed "cytokine cascade" in the circulation more or less concomitantly to the developing febrile response. Also, LPS-like fever can be induced by systemic administration of key cytokines (IL-1ß, TNF-alpha, and others). However, anti-cytokine strategies against IL-1ß or TNF-alpha along with systemic injections of LPS frequently lead to attenuation of the later stages of the febrile response but not of the initial phase of fever, indicating that cytokines are rather involved in the maintenance than in the early induction of fever. Within the last years experimental evidence has accumulated indicating the existence of neural transport pathways of immune signals to the brain. Because subdiaphragmatic vagotomy prevents or attenuates fever in response to intraperitoneal or intravenous injections of LPS, a role for vagal afferent nerve fibers in fever induction has been proposed. Also other sensory nerves may participate in the manifestation of febrile responses under certain experimental conditions. Thus, injection of a small dose of LPS into an artificial subcutaneous chamber results in fever and formation of cytokines within the inflamed tissue around the site of injection. This febrile response can be blocked in part by injection of a local anesthetic into the subcutaneous chamber, indicating a participation of cutaneous afferent nerve signals in the manifestation of fever in this model. In conclusion, humoral signals and an inflammatory stimulation of afferent sensory nerves can participate in the generation and maintenance of a febrile response.

Importance of hyaluronan biosynthesis and degradation in cell differentiation and tumor formation

Hyaluronan is an important connective tissue glycosaminoglycan. Elevated hyaluronan biosynthesis is a common feature during tissue remodeling under both physiological and pathological conditions. Through its interactions with hyaladherins, hyaluronan affects several cellular functions such as cell migration and differentiation. The activities of hyaluronan-synthesizing and -degrading enzymes have been shown to be regulated in response to growth factors. During tumor progression hyaluronan stimulates tumor cell growth and invasiveness. Thus, elucidation of the molecular mechanisms which regulate the activities of hyaluronan-synthesizing and -degrading enzymes during tumor progression is highly desired.

Decreased gastric tone and delayed gastric emptying precede neutrophil infiltration and mucosal lesion formation in indomethacin-induced gastric damage in rats

Gastric antral dysmotility has been implicated in the pathogenesis of indomethacin-induced gastric damage, but the relationship between gastric motor abnormalities and mucosal lesions has not been extensively studied. We investigated whether changes in gastric tone and gastric retention correlate with mucosal lesions and neutrophil migration in indomethacin-induced gastric damage in rats. Indomethacin, either 5 or 20 mg/kg (INDO-5 and INDO-20), was instilled into the stomach, and then gastric damage, neutrophil migration, gastric tone and gastric retention were assessed 1 or 3 h later. Gastric damage was calculated as the sum of the lengths of all mucosal lesions, and neutrophil migration was measured by assaying myeloperoxidase activity. Gastric tone was determined by a plethysmometric method, and gastric retention of either saline or Sustacal® was evaluated by a scintigraphic method. Gastric damage was detectable 3 h after either INDO-5 or INDO-20, but not after 1 h. Neutrophil migration was significantly higher 3 h after INDO-20 as compared with INDO-5 or control group, but not after 1 h. Values of gastric tone 1 and 3 h after either INDO-5 (1 h = 1.73 ± 0.07 ml; 3 h = 1.87 ± 0.03 ml) or INDO-20 (1 h = 1.70 ± 0.02 ml; 3 h = 1.79 ± 0.03 ml) were significantly lower than in controls (1 h = 1.48 ± 0.05 ml; 3 h = 1.60 ± 0.06 ml). Gastric retention of saline was higher 1 h after INDO-5 (58.9 ± 3.3%) or INDO-20 (56.1 ± 3.1%) compared to control (45.5 ± 1.7%), but not after 3 h. There were no differences concerning gastric retention of Sustacal® between the various groups. Indomethacin induced decreased gastric tone and delayed gastric emptying, which precede mucosal lesion and neutrophil infiltration. These results indicate that there is no relationship between these gastric motor abnormalities and mucosal lesion in indomethacin-induced gastropathy.