Soluble Urea Research Articles

455 Response of Irrigated Potatoes to Polyolefin-coated Urea

Polyolefin-coated fertilizers are slow-release fertilizers coated with thermoplastic resins that have a temperature-dependent nutrient release pattern. A field study was conducted on a Hubbard loamy sand during 1997 and 1998 at Becker, Minn., to evaluate the effect of polyolefin-coated urea (POCU) fertilizers (Meister, Chisso Co., Japan) on yield and quality of irrigated `Russet Burbank' potatoes (Solanum tuberosum L.). The coated fertilizers were POCU-50 and POCU-70, which release 80% of their N in 50 and 70 days, respectively, at 25 °C, and a 1 POCU-50: 1POCU-70 mixture. The study compared three soluble urea treatments (N at 0, 140, and 280 kg·ha-1) split-applied at planting, emergence, and hilling vs. the same N rates of coated urea fertilizers applied in a band at planting. In 1997, a season characterized by high leaching, total and large tuber (>168 g) yields were higher with coated urea sources than soluble urea at equivalent N rate, but the N sources gave similar yields in 1998 when leaching was minimal. In both years, doubling the rate of N as soluble or coated urea from 140 to 280 kg·ha-1 had no effect on total yield, but increased the marketable yield (tuber size). Yields were higher in 1998 compared to 1997 due to poorer tuber set in 1997. However, the percentage of large tubers was higher in 1997. Specific gravity increased slightly with N rate but did not differ with N source at equivalent N rate. Hollow heart incidence was similar among all treatments in 1997, but it increased with N rate and was similar among N sources in 1998.

Effects of alternative protein and energy sources on the metabolism and performance of straw fed, pregnant and lactating ewes

Fishmeal is a suitable protein source for pregnant and lactating ewes, providing high levels of undegradable protein (UDP) with a high biological value (Sheehan and Hanrahan, 1989). Vegetable protein sources supply a lower proportion of UDP and lack in supply of essential amino acids, but the quality can be improved by heat / chemical treatment and by adding amino acids. It has also been shown that concentrates can be partially replaced by supplementary feed blocks based on soluble sugars and urea with no adverse effects on production and simplifying the feeding regime (Chapple et al, 1996). The objective of the current experiment was to compare the effects of feeding barley based concentrates containing either fishmeal or a protected vegetable protein as the main protein source and the partial replacement of concentrates with a supplementary feed based on soluble sugars and urea (blocks) on the performance and metabolism of pregnant and lactating ewes.

Some Aspects of Matrix Formation of Flexible Polyurethane Foams

The reaction of liquid raw materials like isocyanates, polyols, and water, to build a structural polymer network is a very complex sequence of different chemical reactions. We can describe some of these essential processes by the use of a dynamic measurement of the viscosity during the course of the foaming reaction, on-line FTIR-spectrometry measurements and the determination of the curing behaviour. We employed a laboratory FT-IR system, that was interfaced to an optical fibre loop. The formation of the soluble and associated urea species, the decay of isocyanate groups and the development of urethane species during the polymerization reaction were studied by FT-IR. The onset of the formation of associated urea species is influenced by the chemical composition of the reacting mixture. For the viscosity measurements we used a rotational viscosimeter. The network development was shown by the determination of the viscosity profile. By extrapolation of the course of the indentation force over time, estimated after the demould of the flexible foam, we determined the green strength of the moulding and the vitrification of the foam at a frozen morphology. We also illustrated the dependence of the mechanical properties of flexible PU foams on the chemical structures formed during the reaction.

An FT i.r. study of reaction kinetics and structure development in model flexible polyurethane foam systems

Forced-adiabatic, FT i.r. spectroscopy has been employed to simultaneously monitor polymerization and microphase separation on model flexible polyurethane foam systems. The following combinations of hydroxy functional components were investigated: (1) polyether-polyol and water; (2) polyether-polyol and deuterium oxide; (3) polyether-monol and water; and (4) polyether-monol and deuterium oxide. The formation of urethane, soluble urea, soluble d-urea, hydrogen-bonded urea and associated d-urea species were monitored during their fast bulk copolymerization with a diisocyanate. The decay of isocyanate is correlated to the polymerization kinetics and the evolution of hydrogen-bonded urea/associated d-urea is analysed emphasizing the onset of microphase separation of urea hard-segment sequences. The microphase separation transition (MST) occurred at a critical conversion of isocyanate functional groups. In the deuterium oxide blown foams, there was no trace of hydrogen-bonded urethane in the spectra obtained. In the polyether-monol systems, a lower conversion of isocyanate was observed at the MST and an overall lower reaction conversion was also observed.

In-Situ Studies of Structure Development during the Reactive Processing of Model Flexible Polyurethane Foam Systems Using FT-IR Spectroscopy, Synchrotron SAXS, and Rheology

FT-IR spectroscopy, synchrotron SAXS, and dynamic rheometry have been employed to monitor, in-situ, structure development during the reactive processing of model flexible polyurethane foam systems. The following combinations of components were investigated: (I) diisocyanate, polyether polyol, and water and (II) diisocyanate, polyether monol, and water. The formation of urethane, soluble urea, and hydrogen-bonded urea species during the fast bulk copolymerization has been studied using the adiabatic reactor method and forced-adiabatic, time-resolved FT-IR spectroscopy. The decay of isocyanate is correlated with the polymerization kinetics, and the evolution of hydrogen-bonded urea is analyzed emphasizing the onset of microphase separation of urea hard segment sequences. FT-IR spectroscopy indicated that the microphase separation transition (MST) occurred at a critical conversion of isocyanate functional groups and followed the kinetics associated with nucleation and growth. The dynamics of microphase separation during the fast bulk copolymerization have also been investigated employing forced-adiabatic, time-resolved synchrotron SAXS experiments. Microphase separation was observed to occur at a critical conversion of isocyanate functional groups and is shown to follow the kinetics associated with spinodal decomposition. Forced-adiabatic rheological measurements have been conducted during the fast bulk copolymerization. Four main regions of rheological development during the formation of polyurethane foam were identified. These were: (I) bubble nucleation, (II) liquid foam and microphase separation, (III) physical gelation, and (IV) foamed elastomer. The use of model systems demonstrated that the presence of covalent cross-links delay the onset of microphase separation of the urea hard segment sequence lengths. Although foam stability is not dependent upon the formation of urethane covalent cross-links in the early part of the foaming reaction, molecular connectivity between the microphases via urethane covalent cross-links is an essential requirement with regard to long-term dimensional stability and the mechanical/physical properties of the foam.

A Comparison of Turfgrass Response to Biologically Amended Fertilizers

Initial release of N from waste materials used as natural organic N carriers for turfgrass may be slow due to the need for microbial degradation. In a greenhouse study, `Rebel' tall fescue (Festucau arundinacea Schreb.) and `Tifway' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] growth response to a natural organic fertilizer (Turf Restore) amended or not amended with a soil-derived microbiological inoculum were compared with soluble urea using sterilized and nonsterilized soil. No interactions of soil sterilization and fertilizers were noted at 19 days after treatment (DAT). Urea fertilizer increased tall fescue growth rates by 68% in the nonsterilized soil and 126% in the sterilized soil compared to rates for turf grown with inoculated Turf Restore. Nitrogen uptake rate was 419% higher with urea-fertilized turf in the sterilized soil than for turf fertilized with inoculated Turf Restore. Soil sterilization at 33 DAT no longer affected turf response, but turf growth rate was 133% higher and N uptake 353% higher with urea fertilization than with inoculated Turf Restore. Infection of the plants with Rhizoctonia spp. at 72 DAT was unaffected by fertilizer treatments. Bermudagrass response was similar to that of tall fescue. Growth rate was 67% and N uptake 51% higher with urea than with Turf Restore through 17 DAT, regardless of inoculant addition. Amendment of the natural organic fertilizer Turf Restore with a soil-derived biological inoculant did not enhance turf growth rate or N uptake nor impact infection with Rhizoctonia spp.

Maleopimaric acid based water thinnable coatings for anodic electrodeposition

This paper deals with the synthesis of water soluble electrodepositable epoxy resins from maleopimaric acid and epoxy resin. Water soluble methylated urea formaldehyde resin and melamine formaldehyde resin were also synthesised for curing purposes. The coating compositions were prepared from water soluble epoxy resins, water soluble MF resin, water soluble UF resin, red oxide of iron and zinc phosphate. Thereafter the optimum conditions for electrodeposition were determined in terms of voltage, time, solid contents, pH and bath temperature. These anodic electrocoatings had good film properties such as scratch hardness, flexibility, impact resistance and resistance to water, acid, alkali and solvent.

Investment Casting with Low-Pressure Injected Water Soluble Urea Pattern

Investment Casting with Low-Pressure Injected Water Soluble Urea Pattern

(Cholestanyloxycarbonyl)benzyl esters as peptide substituents: Conformational properties of fully protected oligo‐L‐lysines with C‐terminal (cholestanyloxycarbonyl)benzyl and benzyl ester moieties

AbstractThis study involves L‐lysine oligo peptides, protected at the N‐terminus by the Nps and at the ε‐amino functions by Boc groups. Two series were prepared from dimer to octamer, one containing the p‐[(cholestan‐3β‐yloxy)carbonyl]benzyl, the other one the benzyl ester group at the C‐terminus. Conformational analyses were performed by IR absorption. The occurrence of the intermolecular β‐structure in the solid state and in CH2Cl2 solution was demonstrated for the highest oligomers. The relative stabilities of the self‐associated species were determined by adding a variety of polar solvents to the CH2Cl2 solutions. The cholestanyl‐containing peptides have a lower propensity to self‐aggregate than the benzyl‐ester analogues. Self‐aggregation and decreasing solubility run in parallel. It was also directly shown that soluble urea derivatives may disrupt intermolecular H‐bonds in CH2Cl2, a point of practical interest, particularly in solid‐phase peptide synthesis.

Ultrastructural effects of ulcerogens.

Agents such as ethanol, aspirin, bile acids, and hypertonic urea and glucose, are capable of breaking the physiological gastric mucosal barrier and may cause ultrastructural injury to the epithelial cells within several minutes of exposure. Ethanol at any pH, and aspirin and bile acids at acid pH, are lipid soluble and diffuse rapidly into surface epithelial cells where a sequence of injury can be documented by electron microscopy. First, the nuclear chromatin becomes clumped and the density of the cytoplasmic ground substance decreases. Second, mitochondria become swollen and the apical cell membrane is distorted. Finally, the apical cell membrane ruptures and the cell disintegrates. Throughout this sequence, the tight junctions between cells appear morphologically intact. In contrast to lipid soluble agents, hypertonic urea and glucose do not diffuse well into surface epithelial cells. Although these agents also cause rapid changes in transmucosal potential difference and ion fluxes, their ultrastructural effects are quite different. Hypertonic urea and glucose initially cause small blebs within the tight junctions and larger vacuoles within the cytoplasm of surface epithelial cells, while the remainder of the cell structure appears normal. More severe injury is characterized by more vacuolization and eventual disruption of epithelial cells. These changes presumably are secondary to osmotic shifts of fluid and electrolytes. Although the 'cytoprotective' effects of prostaglandins have been well described, there is virtually no information at the ultrastructural level concerning the protective effects of prostaglandins with regard to these ulcerogenic agents.

Patterns of Nitrogen Excretion by Embryonic Softshell Turtles ( Trionyx spiniferus ) Developing in Cleidoic Eggs

Embryonic softshell turtles develop inside eggs exchanging little, if any, liquid water with the nest environment. Despite the consequent restriction on availability of water to support development, embryos convert most of the ammonia released in catabolism of proteins into soluble urea rather than insoluble urate, and thereby commit a portion of their limited reserve of water to serve as solvent for metabolic wastes. This finding is contrary to expectations from prior studies of cleidoic eggs.

Hepatic Lipid Accumulation and Intracellular Cholesterol Crystal Formation in Hypercholesterolemic Diabetic Rats

Hypercholesterolemia, induced by feeding rats a diet of cholesterol and cholic acid, can be markedly accentuated by diabetes, resulting in serum cholesterol levels greater than 1000 mg/dl and extensive accumulate of cholesterol in the liver. To examine the cellular events of hepatic cholesterol accumulation in cholesterol-fed diabetic rats, we used a fixative containing digitonin and water-soluble embedment to preserve native lipid structures.Sprague Dawley male rats were made diabetic by intravenous injection of streptozotocin (45 mg/kg body weight) and fed a powdered diet containing 2% cholesterol, 10% lard and 1% cholic acid (CLC) for 3 wk. Non-diabetic rats were also fed CLC diet. Cholesterol, glucose and insulin levels were monitored for both groups. Livers were fixed by perfusion with 3% glutaraldehyde (30°C) and 0.2% digitonin in cacodylate buffer (1 hr), then by 1% OsO4 in buffer for 2 hr. Staining was in 2% uranyl acetate and embedding in water soluble urea glutaraldehyde. Thin sections were stained with lead citrate and viewed in a Zeiss EM-9S.

Thatch Influence on Mobility and Transformation of Nitrogen Carriers Applied to Turf1

AbstractThatch frequently exists as part of the edaphic environment of a turfgrass community and thus, should be considered when attempting to determine the fate of topically applied fertilizers in turf. The purpose of these investigations was to determine the influence of a thatch layer on the vertical mobility and transformation of soluble and slowly soluble N carriers following application.Measurements of N leaching, retention, and volatilization were made using cores of thatch and Flanagan silt loam (Aquic Argiudoll) soil extracted from fieldgrown turf of Kentucky bluegrass (Poa pratensis L.). Urea was selected as the soluble N carrier, and isobutylidene diurea (IBDU) was the slowly soluble N carrier. Application of urea resulted in 2.5 times as much N leaching and correspondingly lower N retention, in thatch than in soil. Where IBDU was used as the N source, leaching from the thatch was reduced from 81 to 5% of the applied N, and leaching from the soil was reduced from 32 to 23% compared to urea‐treated cores. In the volatilization studies, 39% of the applied N from urea was lost as ammonia from thatch cores compared to only 5% from the soil cores. Where IBDU was the N source, little N volatilization (4% from thatch, 2% from soil) occurred. In conclusion, where a substantial thatch layer exists, and turfgrass rooting is largely confined to the thatch layer, use of a slowly soluble N carrier might be preferable over soluble urea for reducing N losses due to leaching and volatilization. As an alternative, effective measures for controlling the thatch may result in greater efficiencies in the use of fertilizer N by the turfgrass community.

A note on rumen ammonia and blood urea levels in steers administered urea or sparingly soluble urea derivates as nitrogen supplements

SUMMARYRuminal ammonia and blood urea levels were compared in fistulated steers eating paddy straw to appetite and given urea alone, urea plus oxalate, and complexes of urea with either formaldehyde (UFC) or oxalate (UOC), introduced into the rumen in a single daily dose. The solubilities of UFC and UOC in rumen liquor were 23·7 and 4·6% respectively of that of urea. Higher levels of ruminal ammonia and blood urea were recorded on urea than on other supplements.

Growth Response of Merion Kentucky Bluegrass to Fertilizer and Lime Treatments1

AbstractThe performance of ‘Merion’ Kentucky bluegrass to 10 fertilizers, applied at three rates, at two pH levels, is herewith reported. Carriers incorporated with fertilizers had little or no effect on grass growth; however, the carrier used in one fertilizer (24‐4‐6) with 23.19% watersoluble nitrogen mixed with reed sedge peat may have absorbed soluble nitrogen to cause slower nitrogen release. Highest total grass yield was obtained from ammonium nitrate and lowest from urea‐form. The lower yields were obtained from less soluble sources of nitrogen while the soluble urea source (45‐0‐0) was intermediate. Loss of nitrogen in the form of ammonia may have accounted for the relatively low yield from this soluble nitrogen source. All fertilizers significantly increased yield of Merion Kentucky bluegrass at pH 4.8 and pH 7.0, but the interaction between fertilizers and pH levels was not significant. There was a highly significant difference in yield among fertilizer sources. Selection of a fertilizer source or form of nitrogen fertilizer should be based on the relative importance of convenience, safety, cost, and response of grass growth.