Scale Micro Research Articles

Initial Delignification and Cellulose Degradation of Conventional and Ethanol-Assisted Ozonation

It has been proposed that the initial regime of pulp ozonation is a diffusion controlled process, due to the low solubility of ozone and its very fast reaction with lignin. However, whether the process is governed by diffusion on a fibre wall scale (macro diffusion control), on a (micro)fibril scale (micro diffusion control), or by reaction with lignin located on the fibre surface followed by diffusion control is an open question. In order to address this, a 31 kappa Hemlock kraft pulp impregnated with acidified (pH = 2.0) water or acidified (pH = 2.0) ethanol-water (70% w/w) was ozonated at high consistency in a differentially operated packed bed reactor. The cellulose degradation and pulp delignification rates were determined from the change in pulp viscosity and kappa number with ozonation time. Transmission electron microscopy (TEM) was used to visualize the lignin distribution of KMnO4 stained fibre walls. The TEM pictures clearly show reacted lighter regions at exposed fibre surfaces, which are sharply separated from unreacted darker areas inside the fibre wall. Therefore, these pictures support the macro diffusion theory. The macro diffusion theory was used to describe the progress of delignification and cellulose degradation as a sharp reaction front moving through the fibre wall from the external fibre surface towards the lumen. In agreement with this so called diffusion controlled shrinking core model, the present experimental results show that the delignification and cellulose degradation increase proportionally with the square root of the ozonation time. The effects of ozone partial pressure and ethanol-water impregnation on the delignification and cellulose degradation rates are also described.

Backscattered Electron Scanning Images of Soil Porosity for Analyzing Soil Compaction around Roots

Thin sections of soil surrounding maize roots were studied in scanning electron microscopy using the backscattered electron mode. The soil is a fine-loamy, mixed, mesic, Typic Eutrochrept. Backscattered electron scanning images (BESI) of the porosity surrounding a selected maize (Zea mays L.) root were studied by image analysis at the scale of micro- and mesopores. Image analysis of BESI revealed that the porosity was 22 to 24% less within the soil surrounding the root than in the bulk soil. The bulk density increased up to 1.80 Mg m−3 close by the root-soil interface, although it was 1.54 Mg m−3 in the bulk soil. The porosity reduction consisted of a removal of the mesopores and a decrease in micropores, which resulted from the packing of skeleton grains with the porous clayey phase. The micropores were affected, although they are usually thought to be altered only with difficulty under natural conditions. A model which was developed earlier for soil compression around roots of plants growing on remolded soils was fitted to the experimental data by nonlinear regression analysis.

Colonialism, Rural Social Structure and Resistance: The Relevance of Kathleen Gough's Work

The Indian Context At the risk of being schematic and simplistic one may suggest that mainstream Sociology and Social Anthropology in India has been dominated, by and large, by two approaches: British structural - functionalism and the Indological approach. The structural - functional approach focussed on small - scale micro - studies of social institutions and cultural practices with no attempt to relate them to the historical context. Moreover, preoccupied with harmony and equilibrium, it ignored the issues of social tensions, resistance and struggles. Studies of kinship, caste, religion and village community -- the main focus of attention in the 1950s and the 1960s -- can be cited as instances of functionalism in Indian Sociology and Social Anthropology. On the other hand, the Indological approach, popularized through the Contributions to Indian Sociology, initiated in 1957 by Louis Dumont and David Pocock (and later on carried on by the Contributions ... [New Series]), focussed its attention on the concepts and categories of social organization in Indian thought embedded in Hindu religious scriptures. In this approach, the cultural specificity of India is misrepresented as the uniqueness of Indian society which is supposedly organized on principles opposite to those governing the organization of society and culture in the West. The most serious problem with this approach is that it takes the concepts and categories out of their context and presents them as trans - historical reality. There is no attempt to look at the tension and the correspondence between the concepts and categories, on the one hand, and the concrete historical reality, on the other. Rather, the concepts and categories are confused with the concrete reality itself. Furthermore, not only does this approach reduce the entire social - economic formation to a constructed notion of dominant Value, but, as Andre Beteille (1987:675) points out, it applies different scales to the dominant Value in the East as opposed to that in the West: societies are valorized in the very acts of comparison and contrast. Beteille calls it the disease of an intellectual climate. In my opinion, however, this is a case of dogmatic application of the orientalist ideology which tends to obscure our understanding not only of the East but also of the West. Kathleen Gough's work marks a bold departure from both Indology and functionalism. Her approach is structural and historical. She is sensitive to the cultural concepts and practices without, however, ignoring their historical context. Given the limitations of time and space, in addition, of course, to my intellectual limitations, it is not possible to review here Gough's work on India in its entirety. Rather, I will confine myself to her concern with peasant resistance and struggles in colonial and post - colonial India. In the spring of 1983, I had an opportunity to meet Kathleen Gough in Vancouver, when she told me that one of the incentives for her to write about peasant movements in India was the publication of Barrington Moore's famous work, Social Origins of Democracy and Dictatorship (1966, cf. Gough 1974). It was not so much the empirical content of Moore's work as the general approach to Indian history and society, especially his representation of Indian peasantry, caste system and traditional village structure as repository of passivity and non - resistance to external (colonial) and internal (post - colonial) domination and oppression that she found unacceptable. She also told me that she was herself preoccupied with her research and writing on Vietnam, but she would very much appreciate if more historically grounded anthropological studies were undertaken to counter the representation of a passive Indian peasantry. Going back to our first meeting at the Post - Plenary Session of the Xth World Congress of Anthropological and Ethnological Sciences, 1979, in Lucknow (India), we had a brief discussion on how Barrington Moore is not alone in taking this particular approach to Indian society and culture, but rather it is part of a more general trend, including the Indological approach briefly referred to above. …

Protective Al2O3 scale formation on NbAl3-base alloys

The oxidation of NbAl3 with additions of Cr and Y was studied to determine the mechanisms of the beneficial effects of these elements upon oxidation. Cr additions to the binary Nb Al3 alloy of up to 6.8 at. % reduced the scale growth rates and promoted α-Al2O3 formation over much longer times relative to binary NbAl3. A major effect of Cr is to form a layer of AlNbCr at the metal/ scale interface, which is inherently more oxidation-resistant than the matrix alloy in the long term. Yttrium additions to a Cr-containing alloy improved the scale growth rate and adherence, and changed the scale micro structure to mimic that of a typical protective Al2O3 scale.

The tectonics of Precambrian craton—mobile belts: progressive deformation of polygonal miniplates

The Archaean—Proterozoic crust of many Precambrian terrains consists of two contrasting tectonic units: Archaean cratonic blocks made up of granite—greenstone terrains and Archaean—Proterozoic mobile zones, fold belts and orogens which separate and tend to surround and flow around the cratons. The cratons are relatively rigid blocks, but have a history of ductile and brittle deformations. The surrounding mobile belts are either high-strain, high-grade metamorphic belts or folded basins. Thus, the relatively rigid cratons are surrounded by more ductile zones of mobility. It is speculated that the Archaean cratons are originally separate, although neighbouring ensialic, polygonal miniplate blocks of a single continent which have moved relative to one another according to the mantle controls and the prevailing Eulerian poles, and this mutual jostling has progressively deformed their common boundaries. The deformed boundaries are now the sites of the surrounding ductile and higher strain mobile belts, which are persistent crustal defects, while the cratons represent the more rigid and lower strain cores and relicts, which have stabilized after the Archaean. The mega-scale relationships between the cratons and mobile belts (e.g., East Africa) are compared to the smaller scale micro—meso-scale porphyroclast-matrix structures found in augen gneisses and mylonites. These structural relationships are of vastly different magnitudes (10 8), but as there exists a continuum on all the intermediate scales they may all be related. Their geometric similarities are interpreted as having a common mechanical—rheological origin.

DETERMINATION ON A MICRO SCALE OF CONCENTRATION AND SPECIFIC RADIOACTIVITY OF INORGANIC PHOSPHATE IONS IN WHOLE BLOOD AND PACKED RED CELLS.

DETERMINATION ON A MICRO SCALE OF CONCENTRATION AND SPECIFIC RADIOACTIVITY OF INORGANIC PHOSPHATE IONS IN WHOLE BLOOD AND PACKED RED CELLS.