A REVISED LOADING AND EXHUMATION MODEL FOR THE SWAKANE BIOTITE GNEISS, CASCADES CRYSTALLINE CORE (CCC), WA: IMPLICATIONS FOR MESOZOIC TECTONICS

Abstract A modified TEMPO-catalyzed oxidation of the solvent-exposed glucosyl units of cellulose to uronic acids, followed by carboxyl reduction with NaBD 4 to 6-deutero- and 6,6-dideuteroglucosyl units, provided a robust method for determining relative proportions of disordered amorphous, ordered surface chains, and anhydrous core-crystalline residues of cellulose microfibrils inaccessible to TEMPO. Both glucosyl residues of cellobiose units, digested from amorphous chains of cellulose with a combination of cellulase and cellobiohydrolase, were deuterated, whereas those from anhydrous chains were undeuterated. By contrast, solvent-exposed and anhydrous residues alternate in surface chains, so only one of the two residues of cellobiosyl units was labeled. Although current estimates indicate that each cellulose microfibril comprises only 18 to 24 (1 , 4)- b eta-D-glucan chains, we show here that microfibrils of walls of Arabidopsis leaves and maize coleoptiles, and those of secondary wall cellulose of cotton fibers and poplar wood, bundle into much larger macrofibrils, with 67 to 86% of the glucan chains in the anhydrous domain. These results indicate extensive bundling of microfibrils into macrofibrils occurs during both primary and secondary wall formation. We discuss how, beyond lignin, the degree of bundling into macrofibrils contributes an additional recalcitrance factor to lignocellulosic biomass for enzymatic or chemical catalytic conversion to biofuel substrates.

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Fluoride releasing kinetics in a weathered bearing biotite gneiss

10.31705/eru.2021.13 ◽

2021 ◽

Author(s):

M.H.Ashan Madusanka ◽

◽

Sandun Sadanayake ◽

lkMeththika Vithanage ◽

◽

...

Keyword(s):

Sri Lanka ◽

Kidney Disease ◽

Dental Fluorosis ◽

Geographic Area ◽

Climatic Conditions ◽

Who Guidelines ◽

Biotite Gneiss ◽

Basement Rocks ◽

Dry Zone ◽

Uncertain Etiology

In several regions of the dry zone of Sri Lanka, excessive quantities of fluoride (F-) in groundwater have affected the water quality significantly. Apart from the well-known prevalence of dental fluorosis, Chronic Kidney Disease of uncertain etiology (CKDu) is widespread in different pockets in the dry zone of Sri Lanka [1]. Fluoride is one of the substances suspected of being causative of CKDu in the area. Since the kidneys retain more F- than in any other soft tissue and excess F- exposure can cause kidney disease. Within the same zone, the prevalence of CKDu varies by geographic area in a ground water and spatial distribution of selected trace elements in groundwater. The optimum F- level in drinking water, according to WHO guidelines, is 1.5 (mg/L); however, due to the unfavorable climatic conditions that exist in tropical countries, people ingest more water than normal intake, resulting in a high F- intake. The source of F- is geogenic. It has been found that the F- content of basement rocks ranges from 9.5×10-5 to 1.44×10-3 kg/L in the region [3]. Farmers consume about 2-3 liters of water a day to quench their thirst, resulting in a daily F- intake of 3×10-3-1×10-2 kg/L [4].

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Red soils of different origins from southwest Nigeria: Characteristics, classification, and management considerations

Canadian Journal of Soil Science ◽

10.4141/s96-069 ◽

1997 ◽

Vol 77 (2) ◽

pp. 295-307 ◽

Cited By ~ 9

Author(s):

T. A. Okusami ◽

R. H. Rust ◽

A. O. Alao

Keyword(s):

Clay Mineral ◽

Agricultural Land ◽

Clay Fraction ◽

Chemical Properties ◽

Cropping System ◽

Clay Content ◽

Parent Material ◽

Classification Systems ◽

Biotite Gneiss ◽

Variable Charge

Representative profiles of the Owena, Egbeda, Alagba, and Balogun series were studied. The Owena soil is formed in amphibolite whereas Egbeda and Balogun soils are formed in biotite gneiss derived parent materials. The Alagba soil is formed in sandstone parent rock. The main objectives were to characterize the soils and their clay fraction, and to classify and interpret soil properties for agricultural land use. Most soils exhibit 2.5 YR hues in subsurface horizons. A pedon formed in biotite gneiss has the highest dithionite Fe content and Fed/clay ratio. The relationships between clay content and Fed values vary according to parent material origin and, therefore, would have to be interpreted differently for soil weathering processes. Clay coatings were noticeable in some soil horizons of all pedons studied. Soils are generally medium to slightly acid with sandstone-derived soils being the most acid. The clay mineral suite in all soils is dominated by kaolinite with traces of 2:1 and 2:2 clay minerals, goethite, hematite, anatase, maghemite, and rutile. In addition, some soils contain trace amounts of gibbsite. Kandic horizons have been identified in all soils. The low charge properties of the soils reflect the intensely weathered clay mineral suite. The base status is probably influenced by the cropping system and therefore may tend to unnecessarily differentiate highly weathered soils at the order level. The Egbeda and Balogun series were classified as Rhodic Kandiudults, clayey-skeletal, oxidic and Rhodic Kandiudalfs, clayey-skeletal, oxidic, respectively. Others, Owena, and Alagba series, were classified as Typic Kanhaplohumults, clayey, oxidic and Rhodic Kanhaplustults, fine loamy or clayey, oxidic, respectively. In the FAO-Unesco legend, all soils become Rhodic Ferralsols. In addition, the Owena (with its nitic properties) is further classified as niti-rhodic Ferralsol. The two classification systems are at variance for highly weathered (variable charge property) soils and this difference will definitely influence management decisions depending on which system is used at any particular time. Soil attributes favorable for agricultural use include thick sola and favorable structures. Chemical properties suggest minimal fixation of phosphorus. Key words: Dithionite Fe, kandic, oxidic, variable charge, ferralic, exchangeable Al

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Late Cenozoic exhumation model of New Zealand: Impacts from tectonics and climate

Earth-Science Reviews ◽

10.1016/j.earscirev.2017.01.003 ◽

2017 ◽

Vol 166 ◽

pp. 286-298 ◽

Cited By ~ 17

Author(s):

Ruohong Jiao ◽

Frédéric Herman ◽

Diane Seward

Keyword(s):

New Zealand ◽

Late Cenozoic ◽

Exhumation Model

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Influence of titanium oxide-based colourants on the morphological and tribomechanical properties of injection-moulded polyoxymethylene spur gears

Journal of Polymer Engineering ◽

10.1515/polyeng-2019-0170 ◽

2019 ◽

Vol 39 (8) ◽

pp. 774-783

Author(s):

Dominik Schubert ◽

Sebastian Hertle ◽

Dietmar Drummer

Keyword(s):

Titanium Oxide ◽

Mechanical Performance ◽

Core Material ◽

Spur Gears ◽

Delivery Methods ◽

White Pigment ◽

Crystalline Core ◽

Coarse Microstructure ◽

Tribomechanical Properties ◽

Carrier Systems

Abstract Regardless of colouration for functional or aesthetic purposes, technical polymer parts, like gears, require consistent properties. However, there is a lack of research into the effect of colourants on the tribomechanical properties of gears. Therefore, the effects of two pigments, titanium dioxide (white) and chrome antimony titanium oxide (yellow), and three delivery methods, masterbatch, liquid colour and direct compounding, on part morphology, dimensions, tribological and mechanical performance of injection-moulded polyoxymethylene (POM) spur gears are investigated in this paper. The white pigment accelerates the crystallisation of POM, causing fine and highly-crystalline morphological structures and smaller dimensions. However, the yellow pigment decelerates crystallisation, resulting in a coarser morphology with highly crystalline core material and bigger parts. Furthermore, the delivery method affects only the tribomechanical properties. Using a masterbatch decreases loads at break and increases deflection at break, since the carrier material acts as an impact modifier and a weak spot. The liquid colour decreases wear due to lubricating properties, whereas the pure pigments increases abrasion, especially in combination with a coarse microstructure. However, the effects of carrier systems and changes in morphology are always superimposed. Considering the performance and tolerance of technical components, colourants have to be carefully selected to ensure beneficial properties.

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