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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 898 for “"urea"”.
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Urea Biosynthesis in Chelonian Reptiles
No abstract prepared.
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The synthesis of ethylene urea
Thesis: M.S., Massachusetts Institute of Technology, Department of Mechanical Engineering, 1939
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Ammonia Volatilization, Urea Hydrolysis, and Urease Inhibition with the Application of Granular Urea in Agroecosystems
… The most widely used N source globally is urea; however, N loss via ammonia volatilization can be great in agricultural systems where urea is surface-applied. The objectives of the experiments reported in this dissertation were: 1) evaluate the performance of a new laboratory ammonia …
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Functional Nanomaterials From Bis-Urea Macrocycles
<p>Self-assembly of bis-urea macrocycles usually give tubular crystals with nano-sized channels that we use as molecular container. These molecular containers alter the reactivity, stability, and chemical behavior of the reactants entrapped within them. This dissertation is focused on bulk …
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Urea-N Recycling in Lactating Dairy Cows
… (RDP) and rumen undegradable protein (RUP) on urea-N recycling and microbial N flow. Eight mid-lactation Holstein cows were assigned to a repeated 4 x 4 Latin square. The diets were isoenergetic with RDP and RUP concentrations arranged in a factorial design (10.0 and 12.5% RDP and 5.6 and 8.1% …
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Urea Cycle Operation in the Diabetic Rat
Made available in DSpace on 2015-05-13T15:27:01Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 8009054.PDF: 7191925 bytes, checksum: 466f13c20f12839eead745ebafb7aa74 (MD5) Previous issue date: 1979
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Urea and Ammonia Metabolism in the Ruminant
Made available in DSpace on 2014-12-09T14:28:52Z (GMT). No. of bitstreams: 1 6604152.pdf: 2312969 bytes, checksum: c768271ad3fc0023e6220397d87d9811 (MD5) Previous issue date: 1965
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Rice Grain Yield and Nitrogen Uptake and Ammonia Volatilization from Urea as Affected by Urea Amendment and Simulated Rainfall
<p>The effect of rainfall between urea application and flood establishment on N loss and grain yield of rice (Oryza sativa L.) has not been studied. The first research objective was to compare the effects of simulated rainfall amounts and N-(n-butyl) thiophosphoric triamide (NBPT) urease inhibitor …
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Urea as an Effective Nitrogen Source for Cyanobacteria
Urea use has grown substantially in the past half-century, with urea now accounting for > 50% of nitrogen fertilizer applications worldwide. The shift from inorganic nitrogen fertilizers to urea-based sources has coincided with the reappearance of cyanobacteria blooms in freshwaters. Here, we …
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Electrochemical Pathways to Decarbonizing Urea and Ammonia Production
Climate change presents one of the most urgent challenges of the 21st century, and chemical engineers have a critical role to play in addressing it by designing processes that not only minimize carbon emissions but also have the potential to reverse them. This thesis focuses on decarbonizing the …
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Urea adducts of the esters of stearic acid
<p>Urea forms crystalline complexes with n-alkanes and their liner derivatives but not with most branched and cyclic hydrocarbons and their derivatives. The compounds are stable enough to be used in separating these types of aliphatic compounds from their branched and cyclic analogs. Linear esters …
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Sulfur coating of urea in shallow spouted beds
Sulfur coated urea (SCU) is an effective and economical slow-release nitrogen fertilizer, and its production in a spouted bed was investigated. SCU was produced by batch and continuous operations. Higher quality products were typically produced by the batch process, but at significantly lower …
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Synthesis and characterization of polydimethylsiloxane-urea segmented copolymers
… for the preparation of polydimethylsiloxane-urea (A-B)n segmented or multiblock copolymers has been investigated. These copolymers were synthesized from 4,4¹-diphenylmethane diisocyanate (MDI) and a,ω-bis(aminopropyl)polydimethylsiloxane (PSX) of different molecular weights by solution …
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Evaluation of Urea Ammonium-Nitrate Fertilizer Application Methods
… recommendations for corn. Injection of Urea Ammonium-Nitrate (UAN) may reduce N-loss via ammonia (NH?) volatilization compared to current surface application methods. This study evaluated injection and surface-banding application techniques of UAN in two ways: (1) by conducting a …
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Some physico-chemical and biological aspects of urea
1. Mechanisms of urea adsorption by soils Physically adsorbed urea may be easily desorbed by dilution. Chemisorbed urea existing primarily in the form of relatively stable soil organic matter-urea complexes may, in part, be slowly dissociated upon dilution. Differences between soil types with …
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Siloxane modified polyurea and polyurethane urea segmented copolymers
High molecular weight polyether urea copolymers were synthesized using perfectly difunctional aromatic amine terminated polypropylene oxide (PPO) (2800 <Mn>) prepared via aluminum porphorin initiated coordination polymerization. The resulting segmented copolymer showed much higher tensile strength …
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The urea adducts of certain esters containing twenty carbons
<p>Urea has the interesting and unexpected property of forming solid complexes with many straight-chained organic compounds. So selective is the formation of these complexes with linear aliphatic compounds that it provides a means of separation form the analogous branched and cyclic compounds. …
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Development and experimental investigation of direct urea fuel cells
… and experimental investigation of Direct Urea-Hydrogen Peroxide Fuel Cells (DUHPFC). The research focuses on preparing electrodes using nickel zinc iron oxide on stainless steel foil and evaluates single cells and stacks under varying conditions. Optimal single-cell performance is achieved …
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