Gum Formation Research Articles

A chemical investigation of shale oil ageing

Chemical changes resulting from exposure of Stuart and Nagoorin (Queensland, Australia) Fischer assay oils to oxygen at 45 °C for 4000 h were investigated by n.m.r., g.c.-m.s. and potentiometric titration techniques. The most significant reactions, which were all accelerated by visible light, involved oxidation of alkenes, phenols and pyrroles. A possible mechanism of gum formation is given.

Vessel Occlusions in Plants: Morphological, Functional and Evolutionary Aspects

The minimum pit aperture diameter of a vessel-parenchyma pit pair was found as the decisive wood anatomical feature for vessel occlusion by either tyloses or gums. Based on this observation, as well as on considerations and established knowledge about the functional significance of vessel occlusions, an evolutionary hypothesis is presented. In order to withstand microorganisms and embolisms, plants are able to occlude their vessels with tyloses or gums. The most primitive Angiosperms show tylosis formation. With the decreasing pit sizes in the vessel wall during plant evolution, gum formation was developed, whereas the increasing vessel sizes led in some plants to renewed tylosis formation.

Spectrophotometric studies of storage stability of jet fuel

Accelerated oxidation tests, using a modification of the ASTM D 2274 testing method, were carried out on a commercially available jet fuel of ASTM type A1. The extent of degradation was followed spectrophotometrically using fresh fuel as reference. It was established that this analytical method can be used to determine the amount of soluble gum in the fuel with a detection limit of 6 mg gum per litre of fuel. The activation enthalpy of gum formation was determined to be 90.8 ± 0.4 kJ mole −1, and the activation enthalpy of the antioxidant consumption was 133.1 ± 0.4 kJ mole −1.

The composition of the proteinaceous gums exuded by some Leucaena species, subspecies and hybrids

Analytical data are presented for the sugar and amino acid compositions of the gum exudates from Leucaena leucocephala (four specimens), L.pallida, L.leucocephala × L.pallida (two specimens) and L.lanceolata subsp. sousae (two specimens). Conversion factors have been calculated from the amino acid data to facilitate the conversion of Kjeldahl nitrogen values to protein contents; the factors are considerably higher than that assumed in an earlier study of Leucaena gum. The data confirm and extend the previous indication that Leucaena gum has a strongly negative specific rotation, with sugar and amino acid compositions that are similar to those of commercial gum arabic [ Acacia Senegal (L.) Willd.]. Commercial possibilities and mechanisms of gum formation are discussed.

Gum and deposit formation from jet turbine and diesel fuels at 100.degree.C

Rates of oxidation and gum formation for six hydrocarbons, three jet turbine fuels and three diesel fuels have been measured at 100/sup 0/C in the presence of t-Bu/sub 2/O/sub 2/ as initiator. Four of the six fuels oxidize faster at 100/sup 0/C than in previous work at 130/sup 0/C without initiator. For any single substrate, the amount of gum produced for the oxygen absorbed is similar at 100 and 130/sup 0/C, even with large changes in rates and t-Bu/sub 2/O/sub 2/ concentrations. In general, the pure hydrocarbons have long kinetic chains and give good yields of hydroperoxides.

Gum and deposit formation from jet turbine and diesel fuels at 130.degree.C

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGum and deposit formation from jet turbine and diesel fuels at 130.degree.CFrank R. Mayo and Bosco Y. LanCite this: Ind. Eng. Chem. Prod. Res. Dev. 1986, 25, 2, 333–348Publication Date (Print):June 1, 1986Publication History Published online1 May 2002Published inissue 1 June 1986https://doi.org/10.1021/i300022a036RIGHTS & PERMISSIONSArticle Views181Altmetric-Citations19LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-Alerts

PREVENTION OF GUM FORMATION AND VISCOSITY INCREASES IN COAL-DERIVED DISTILLATE FUELS

ABSTRACT Metal chelating additives at 1% w/w do not prevent gum precipitation and/or viscosity increases in coal-derived distillate fuels stored in air at 50°C. However, distillates containing 10-15% w/w of added cyclohexanol, dipropylamine, ethylmethylketone or iso-propanol do not precipitate gum or increase in viscosity under simulated storage conditions. Data for cyclohexanol/fuel mixtures suggest that gum formation is inhibited by hydrogen-bonding between cyclohexanol and fuel constituents.

Gummosis in Prosopis cineraria (L.) Druce

Summary Gummosis in Prosopis cineraria is due to the mechanical injury to the vascular cambium, resulting the formation of gum cavities in the inner secondary phloem of stem. Histological study revealed the gum cavities develop schizo-Iysigenously. Degradation of the cell walls seems to contribute the gum formation. Lumen of the cavity shows the gummy material and disorganised isolated cells. Present result suggest that gum cavity development is a plant adaptation to wounds.

Thermolysis of Carbohydrates in Oxygen‐free Atmosphere. Part II. British Gum Formation

AbstractPotato starch was heated to 190, 200 and 210°C in oxygen‐free atmosphere (nitrogen and carbon dioxide) and in the air for comparison. The atmosphere has some influence upon the course of the process as well as properties of resulting British gums.

Methyl and ethyl soybean esters as renewable fuels for diesel engines

AbstractThe primary problems associated with using straight soybean oil as a fuel in a compression ignition internal combustion engine are caused by high fuel viscosity. Transesterification of soybean oil with an alcohol provides a significant reduction in viscosity, thereby enhancing the physical properties of the renewable fuel to improve engine performance. The ethyl and methyl esters of soybean oil with commercial diesel fuel additives revealed fuel properties that compared very well with diesel fuel, with the exception of gum formation, which manifested itself in problems with the plugging of fuel filters. Engine performance using soybean ester fuels differed little from engine performance with diesel fuel. A slight power loss combined with an increase in fuel consumption were experienced with the esters, primarily because of the lower heating value of the esters than for diesel fuel. Emissions for the 2 fuels were similar, with nitrous oxide emissions higher for the esters. Measurements of engine wear and fuel‐injection system tests showed no abnormal characteristics for any of the fuels after the 200‐hr tests. Engine deposits were comparable in amount, but slightly different in color and texture, with the methyl ester engine experiencing greater carbon and varnish deposits on the pistons.

Hydrotreatment of Cracked Light Gas Oil

Abstract Since worldwide conversion processes are used to upgrade heavy oil to distillates, the hydrotreatment of light gas oil (LGO) as a downstream process has been used more extensively. This fraction (LGO) is produced from thermal or catalytic cracking or hydrocracking processes. It contains high amounts of unsaturates, nitrogen, and sulfur compounds which cause instability while in storage due to gum formation. The use of LGO as a fuel oil for diesel engines plugs the filter and produces sulfur and nitrogen emissions. These sulfur and nitrogen compounds arise from the cracking of heavy cuts and are aromatic-type molecules which are difficult to hydrogenate. This cut also possesses a low cetane index (CI) which must be increased (by aromatic hydrogenation) because of its poor motor performance. Color and color stability are associated with a high bromine number (BN, unsaturated content), nitrogen, and aromatic content. In order to improve these properties, a deep hydrogenation is sometimes required.

Development, Structure and Histochemistry of Gum Cavities in Pterocarpus marsupium Roxb. and Azadirachta indica Juss.

In the young stem of Pterocarpus marsupium and Azadirachta indica gum cavaties are associated with the gum formation. The gum in a cavity is formed as a result of breakdown of cells lining the cavity. During their degradation, a number of histological and histochemical changes are obseryed in these cells before they contribute to the gum formation. In Pterocarpus marsupium the cells lining the cavity appear radially elongated and show increased stainability, deposition of tannin granules and presence of fungal hyphae. In Azadirachta indica these cells show dense stainability, deposition of tannin granules and lignification of their walls which swell to great extent before degradation. Bacteria have also been located in the cavity in Azadirachta indica . The probable roles of fungal and bacterial pathogens in relation to cell degradation have been discussed.

Gummosis of stone‐fruit trees and their fruits

AbstractThe factors that affect gum formation in stone‐fruit trees share the common feature of stimulating ethylene production in plant tissues. It is suggested that ethylene might play an important role in gummosis. The chemical structure of the exudate gums is similar to that of certain cell‐wall polysaccharides and it is possible that gummosis is caused by excessive formation of these polysaccharides as a result of ethylene production in the tissues.

Ethephon-Induced Gummosis in Sour Cherry (Prunus cerasus L.)

Ethephon, (2-chloroethyl)phosphonic acid, was sprayed at concentrations up to 69.2 millimolar to enhance gum formation in 1-year-old shoots of mature Prunus cerasus L. cv Montmorency trees. Gum accumulation caused rupturing of the shoot periderm, followed by gum extrusion. Lower ethephon concentrations were required to induce gum formation in spring and early summer (1.7-3.5 millimolar) then in late summer and fall (13.8-69.2 millimolar). The number of functional vessels, shoot hydraulic conductance, and water potential of both leaf and internode tissue decreased as gum content of shoots increased. Nontreated control shoots also contained small quantities of gum. There was no difference in neutral sugar composition of gum exuded by the tree, obtained from aqueous shoot extracts, or flushed from the vessels of shoots, whether induced by ethephon or not. Severe decrease in shoot and leaf water potential was associated with shoot die-back. Recovery of xylem function may occur where gummosis is less severe. Discrepancy between measured and predicted hydraulic conductance increased as shoot gum content increased, suggesting that decrease in number of functional vessels alone was not sufficient to explain the effects of gum on loss of shoot hydraulic conductance. Increased gum content in those vessels remaining functional would increase vessel sap viscosity and further reduce hydraulic conductance. The viscosities necessary to account for discrepancy between measured and predicted hydraulic conductance were calculated. Gum concentration less than 1.0% (w/v) would produce these viscosities.

Fuel Characteristics of Vegetable Oil from Oilseed Crops in the Pacific Northwest1

AbstractIn recent years, the agricultural industry has been threatened by the increased costs and limited supplies of petroleum fuels.The purpose of this research was to evaluate vegetable oil from various oilseed crops adapted to the Pacific Northwest as a potential source of liquid fuel for diesel engines. Sunflower (Helianthus annuus L.), oleic and linoleic safflower (Carthamus tinctorius L.), and low and high erucic acid rapeseed (Brassica napus L.) oils were evaluated for fatty acid composition, energy content, viscosity, and engine performance in short‐term tests. During 20‐min engine tests power output, fuel economy, and thermal efficiency were compared to diesel fuel. The long‐term effect of using linoleic safflower oil as a fuel was evaluated in a single cylinder diesel engine operated for 830 hours.Vegetable oils contained 94 to 95% of the energy content (KJ/L) of diesel fuel, but were 11.1 to 17.6 times more viscous. Viscosity of the vegetable oils was related to fatty acid chain length and number of unsaturated bonds (R2 = 0.99). During short‐term engine tests, all vegetable oils produced power outputs equivalent to diesel, and had thermal efficiencies 1.8 to 2.8% higher than diesel. After 830 hours of operation, linoleic safflower oil formed extensive carbon deposits in the combustion chamber and exhaust port and heavy gum deposits on the injector and compression rings. The development of an additive package to inhibit carbon and gum formation is essential before pure vegetable oils can be used for long‐term operation of diesel engines.

Developmental and Histochemical Studies on Gum Ducts in Terminalia crenulata Roth

Summary In Terminalia crenulata the gum ducts in the young stem and leaf develop lysi-schizogenously. The cells lining the duct show the presence of gum substance and lipid bodies. The cell walls facing the duct lumen show fan shaped radiating fibrillar structures during disorganization, and contribute to gum formation.

Influence of gas phase on formation of fuel-soluble gum and insoluble sediment

Influence of gas phase on formation of fuel-soluble gum and insoluble sediment

Xanthomonas ampelina . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Xanthomonas ampelina . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Vitis vinifera . DISEASE: Bacterial blight of the grapevine, 'Tsilik marasi' in Greece; 'Maladie d'Oleron' in France, 'Vlamsiekte' in South Africa. In early spring, buds on infected spurs fail to open or make stunted growth which eventually dies. Affected spurs often appear slightly swollen because of hyperplasia of the cambial tissue. Cracks appear along such spurs, become deeper and longer, forming cankers. Young shoots may develop pale yellowish-green spots on the lowest internodes. These expand upwards on the shoot, darken, crack and develop into cankers. Cracks and, later, cankers also form on more woody branches later in spring. In summer, cankers are often seen on the sides of petioles, causing a characteristic one-sided necrosis of the leaf. They may also appear on main and secondary flower and fruit stalks. Leaf spots and marginal necrosis occur sometimes. Gum formation is not necessarily a symptom. GEOGRAPHICAL DISTRIBUTION: Greece, France and South Africa (51, 551). The symptoms have been reported from other countries and attributed to Erwinia vitivora , which is now thought to be synonymous with E. herbicola (CMI Descript. 232). Such reports have come from Italy, Sicily, Spain, Portugal, Switzerland, Austria, Yugoslavia, Bulgaria, Tunisia, Canary Islands and Argentina (31, 105; Du Plessis, 1940; Panagopoulos, 1969). Many of these records are almost certainly of X. ampelina . TRANSMISSION: Most information is based on observational data rather than on experiments. Bacteria overwinter in the vines, emerge, probably in spring and are carried to healthy shoots, most probably in wind and rain. Wounds may facilitate entry but are not needed for primary infection. Considerable spread can occur in propagating material, by grafting and by pruning knives. More knowledge should be gained now that the true pathogen is known.

Effect of carbon dioxide on fuel stability under storage conditions

1. Carbon dioxide, when used as an inert gas medium for filling the free space in tanks and reservoirs, limits the sediment formation, wards off the formation of oxidation products and existent gum, and stabilizes the acid number and cloud point of the fuel. 2. The favorable stabilizing effect of carbon dioxide on fuel oxidation in storage is retained at gas-phase CO2 concentrations down to 60%.

Effect of oxygen on sediment and gum formation in fuels

1. In the TSRT-2 apparatus (phase ratio 3.5/1) in 5-h tests at 150°C, establishing a nitrogen medium in the vapor space gives a fivefold to ninefold reduction of the amounts of gum and sediment formed. 2. T-1 fuel that has been “nitrogenated” behaves like a high-stability hydrogenated fuel with respect to filter plugging in pumping tests at 180°C. 3. “Nitrogenation” of fuels favors a reduction of carbon deposit formation on combustion chamber walls, does not decrease the completeness of combustion, and does not narrow the limits of stable combustion chamber operation.