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* old and bologna study programme


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Preliminary estimation of bryophyte biomass and carbon pool from three contrasting different vegetation types
Mahesh Kumar Singh, Anita Juhász, Zsolt Csintalan, Mitja Kaligarič, Michal V. Marek, Otmar Urban, Zoltán Tuba, 2005, published scientific conference contribution

Abstract: Bryophytes are the primary form of carbon storage in many ecosystems. There is growing consensus within the scientific community that increases in atmospheric carbon dioxide (CO2) enhancing the earth's natural greenhouse effect. Because of the potential effects of these gases on the global enery budget and future elimate, there is an urgent need to quantify terrestrial sources and sinks of carbon. There is more carbon stored in some bryophytes than in any other genus of vascular or non-vascular plants (Clymo & Hayward, 1982). Predicting how the vast stores of carbon in moss-dominated ecosystems will be affected by anthropogenic disturbance is critical for models of global climate change (Post et al., 1982). Bryophytes are a prominent feature of many forest and grassland types, where they can make an important contribution to carbon balance (Delucia, et al., 2003). Tropical montane rain forest, because of their complexity and variety of microhabitats, usually harbors a rich diversity of bryophytes. Even though they are often small and inconspicuous, especially in the lowland forest, they may play a significant role in the forest ecosystem (Frahm, 1994). Similarly, bryophytes in the temperate forest and grasslands are thought to be an important carbon sink (O'Neill, 2000). The objective of this research was to estimate components of the bryophyte biomass and approximate amount of carbon stored in it.
Keywords: vegetation, habitats, geoelements, carbon, carbon storage, bryophyte, bryophyte biomass
Published: 07.06.2012; Views: 1066; Downloads: 71
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Zeolitization characteristics of fly ashes from wet- and dry- disposal systems
Bhagwanjee Jha, D. N. Singh, 2012, original scientific article

Abstract: The fly ash disposal at thermal power plants is either through wet- or dry-disposal systems. As these disposal practices result in different characteristics for the fly ashes, their interaction with alkalis, and hence the zeolitization potential, will be different. In order to demonstrate this, investigations were conducted to study the physical, chemical, mineralogical and morphological characteristics of the residues of the fly ashes collected from the lagoons and hoppers of the same thermal power plant, after their hydrothermal treatment. Field-emission-gun scanning electron microscopy and X-ray diffraction analysis of these residues demonstrated that the hopper ash attains an exceptionally high cation-exchange capacity and $SiO_2/Al_2O_3$ ratios (SAR), which correspond to the formation of major fly ash zeolites as compared to its counterpart. In other words, the study presented here helps to establish the superiority of hopper ash over lagoon ash for synthesizing fly ash zeolites and their enhanced quantity and quality.
Keywords: alkali activation, lagoon ash, hopper ash, fly ash zeolites
Published: 13.06.2018; Views: 273; Downloads: 52
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Investigations to establish the influence of the thermal energy field on soil properties
Srinivas Kadali, Susha Lekshmi, Susmita Sharma, D. N. Singh, 2013, original scientific article

Abstract: This paper describes details of a study to investigate and demonstrate the changes undergone by soil when it is exposed to elevated temperatures. Such situations are commonly encountered while designing the foundations for the furnaces, boiler units, forging units, brick kilns, rocket launching pads, buried power-supply cables, air-conditioning ducts, underground explosions, disposal of high-level radioactive and industrial toxic wastes, ground modifications or soil-stabilization techniques, etc. As such, investigations to establish changes undergone by the soil when it is exposed to elevated temperatures assume some importance. With this in view, individual samples of six soils, with entirely different characteristics, were subjected to temperatures up to 300°C (sequentially in steps of 50°C) and after each step of thermal treatment, these samples were characterized for their physical, chemical and mineralogical properties. Based on a critical synthesis of the results, it has been demonstrated that elevated temperatures cause (i) a change in the color, (ii) an increase in the specific gravity, particle size and weight loss, (iii) a reduction in the specific surface area, cation-exchange capacity and zeta-potential, and (iv) a structural transformation of the soil. Though these changes would affect the engineering properties of the soil to a large extent, the scope of this paper is limited to demonstrating the alterations in physical, chemical and mineralogical changes, only, occurring in the soil when it is exposed to elevated temperatures.
Keywords: elevated temperatures, soil, characterization, physical characteristics, chemical characteristics, mineralogical characteristics
Published: 14.06.2018; Views: 279; Downloads: 17
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Formation of meso- and micro-pores in fly-ash zeolites using a three-step activation
Bhagwanjee Jha, D. N. Singh, 2014, original scientific article

Abstract: Researchers have comprehensively characterized alkali- activated fly-ash (the residue) and ascertained its highly zeolitic nature. In order to evaluate its potential for application as an adsorbent for the decontamination of waste water, the decisive parameters have mostly been the cation-exchange capacity, the mineralogy and the morphology of the residue. However, a study of the pore characteristics (e.g., the size and volume) of such residues is still warranted to anticipate their contaminant transport and the diffusion phenomena as a type of geotechnical engineering material. In this situation, the present study demonstrates the evolution of pores in the fly-ash after alkali activation up to three steps, and simultaneously, its effects` on other characteristics (e.g., the specific gravity, specific surface area and the cation-exchange capacity) of three types of similarly synthesized residues (the first, produced by using a NaOH aqueous solution and the other two residues, the result of alkali activation using a NaOH spent solution, the filtrates). Based on N2 gas absorption isotherms and infrared transmittance spectra, residues obtained from the second and third steps, each involving 24 hours of treatment using filtrates of 1.5-M NaOH, are established to be significantly enriched in the finer meso- and micro-pores, respectively, in comparison with a pure and macro-porous zeolite 4A.
Keywords: fly-ash, hydrothermal treatment, three-step activation, pore characteristics
Published: 14.06.2018; Views: 208; Downloads: 38
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