Decoding Geometric Origin of Geomechanical Properties

Granular materials such as soil and aggregate, are ubiquitous in nature and the understanding of their mechanical behavior is of great importance to better predict and design the civil infrastructure. The particle geometry is a key information to robustly establish the link between the underlying grain-scale mechanisms and the macroscopic behavior of granular materials. However, the characteristics of the particle geometry remain to be better understood. For example, we do not know how the volume is related to the surface area for irregularly shaped particles in general. Their relation clearly depends on the morphology, dictating that volume, surface area, and morphology are interrelated. Then, the remaining question is how the size of a particle would be related to those three geometric properties. The interrelation of these four geometry parameters is the key information to fundamentally understand their concerted influence on the complex behavior of granular materials, but we do not have the answer in the body of knowledge yet. The research in this dissertation advances the understanding of grain-scale origin of the complex macroscale behavior of granular materials and creates a set of new knowledge as follows: (i) This study systematically addresses the influence of coarse aggregate angularity on cemented granular materials. It shows that cemented granular materials with round aggregates have superior small-strain performance, while the materials with angular aggregates have superior large-strain performance; (ii) This study develops a new theory for comprehensive 3D particle geometry characterization by proposing a formulation M = A/V×L/6, which translates the 3D particle morphology M as a function of surface area A, volume V, and size L; (iii) This dissertation is benefited by the early adoption of 3D-printing for geomechanical testing. Laboratory direct shear tests have been conducted on 3D-printed synthetic particles with different geometry, to robustly correlate the geometric properties of particles to geomechanical properties of the granular materials. (iv) This study unravels, for the first time, the power law relationship between A/V ratio and V for coarse aggregate in nature. This relationship is the key to predict morphology using volume measurement only, thus significantly reducing the effort of particle geometry characterization

Numerical Investigation of Biogrout: a New Soil Improvement Method Based on MICP

Ground improvement is essential in regions where the desired mechanical properties of soil are not suitable for the particular use. Microbial induced calcite precipitation (MICP) offers an alternative solution to a wide range of civil engineering problems. The microbial urease catalyzes the hydrolysis of urea into ammonium and carbonate. The produced carbonate ions precipitate in the presence of calcium ions as calcium carbonate crystals. Recently, MICP has also been shown to improve the undrained shear strength, confined compressive strength, stiffness and liquefaction resistance of soils and offers potential benefits over current ground improvement techniques. Biogrout is the new ground improvement method where MICP is used to achieve soil strength and stiffness. There is a need to clearly understand the various bio-geo-chemical processes that take place during biogrout in order to predict the enhancement in different mechanical properties of soil. The aim of this master's thesis is to present a numerical model for biogrout process for one-dimensional column experiment, investigating the influence of different injection schemes on the distribution of precipitated calcite within the porous media. In this work, a multi-component bio-geo-chemical model was used, based on the coupled code OpenGeoSys-PhreeqC. The applied model describes the physical and chemical process during the different injections. The results show that the reduction of porosity and permeability can be manipulated using different injection schemes

Potential use of sugar binding proteins in reactors for regeneration of CO(2 )fixation acceptor D-Ribulose-1,5-bisphosphate

Sugar binding proteins and binders of intermediate sugar metabolites derived from microbes are increasingly being used as reagents in new and expanding areas of biotechnology. The fixation of carbon dioxide at emission source has recently emerged as a technology with potentially significant implications for environmental biotechnology. Carbon dioxide is fixed onto a five carbon sugar D-ribulose-1,5-bisphosphate. We present a review of enzymatic and non-enzymatic binding proteins, for 3-phosphoglycerate (3PGA), 3-phosphoglyceraldehyde (3PGAL), dihydroxyacetone phosphate (DHAP), xylulose-5-phosphate (X5P) and ribulose-1,5-bisphosphate (RuBP) which could be potentially used in reactors regenerating RuBP from 3PGA. A series of reactors combined in a linear fashion has been previously shown to convert 3-PGA, (the product of fixed CO(2 )on RuBP as starting material) into RuBP (Bhattacharya et al., 2004; Bhattacharya, 2001). This was the basis for designing reactors harboring enzyme complexes/mixtures instead of linear combination of single-enzyme reactors for conversion of 3PGA into RuBP. Specific sugars in such enzyme-complex harboring reactors requires removal at key steps and fed to different reactors necessitating reversible sugar binders. In this review we present an account of existing microbial sugar binding proteins and their potential utility in these operations

Molecular Study of Micrornamediated Regulation of Mitosis and its Impact on Oral Carcinogenesis

Cancer is a complex disorder, a group of more than 100 diseases that develop across time and involve the uncontrolled proliferation of the body's cells. Although cancer can develop in virtually any of the body's tissues, and each type of cancer has its unique features, the basic processes that produce cancer are quite similar in all forms of the disorder [1]. In this multistep process, cells acquire a series of mutations that eventually lead to unrestrained cell growth and division, inhibition of cell differentiation, and evasion of cell death. These cells break free from the normal restraints on cell division and begin to follow their own agenda for proliferation (Fig. 1). A tumour, formed of these abnormal cells may remain within the tissue in which it originated (in situ cancer), or it may begin to invade nearby tissues (invasive cancer). An invasive tumour is said to be malignant, and cells shed into the blood or lymph from a malignant tumour are likely to establish new tumours (metastases) throughout the body

A nonradioactive assay method for determination of enzymatic activity of d-ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco)

A sensitive and nonradioactive assay method for activity determination of Rubisco is described. The method is based on thin-layer chromatographic separation of 3-phosphoglycerate (3-PGA) and d-ribulose-1,5-bisphosphate (RuBP). This assay method allows the quantitative determination of Rubisco activity. Rates of carbon dioxide fixation on RuBP determined by this method were comparable to those obtained independently by other methods. This assay method is reproducible and relatively free from interference

Biochemical engineering: cues from cells

Engineering principles are used in the exploitation of biocatalysts derived from cells. The purity of reagents, catalysts and maintenance of operation variables are extremely important for bioengineering systems. Any change in the purity of reagents or in operation variables usually leads to a dramatic decrease in productivity. Cellular systems, however, are able to work with relatively high impure conditions and increase their productivity in response to external signals. Thus the seemingly disordered ‘bag of juice’ or cytoplasm has more order and much higher order of integration than first appears. Learning the semantics of this paradoxical ability of order and integration would help bioengineers to understand and enhance productivity even using impure reagents