Rock fractures control many of Earth's dynamic processes, including plate-boundary development, tectonic earthquakes, volcanic eruptions, and fluid transport in the crust. An understanding of rock fractures is also essential for effective exploitation of natural resources such as ground water, geothermal water, and petroleum. This book combines results from fracture mechanics, materials science, rock mechanics, structural geology, hydrogeology, and fluid mechanics to explore and explain fracture processes and fluid transport in the crust. Basic concepts are developed from first principles and illustrated with worked examples linking models of geological processes to real field observations and measurements. Many additional examples and exercises are provided online, allowing readers to practise formulating and quantitative testing of models. Rock Fractures in Geological Processes is designed for courses at the advanced undergraduate and graduate level but also forms a vital resource for researchers and industry professionals concerned with fractures and fluid transport in the Earth's crust.

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Rock Fractures in Geological Processes

Heterotrophic cultivation of microalgae for pigment production: A review

The production of biodiesel can be accomplished using a variety of feedstock sources. Plant and microalgae based feedstocks are prominent and are studied extensively. Plant based feedstocks cultivated as monoculture on wastelands and trees in forests can cater towards partial fulfillment of feedstock requirements for biodiesel industry. Synthesis of biodiesel from microalgal oil has gathered immense interest and has potential to cater to the increasing feedstocks demands of the biodiesel industry. The major advantage offered by microalgal oil, as compared to plant based oils, is its potential for culture on non-arable land. Despite of the advantages of microalgal oil as a feedstock for biodiesel, there are constraints that have to be overcome in order to make it economical and sustainable. Sustainable approaches for both the plant and microalgae as feedstocks have been drawn. Despite there being several plant species, few have been found to be desirable as feedstocks for biodiesel production based on their lipid profiles. Among the microalgae, there are thousands of species and several of these have been cultured for extracting the oil to explore their feasibility in utilization as biodiesel feedstocks. Though, several of the microalgal species have shown potential for high biomass growth and lipid productivity, only a few have been found to provide a high biodiesel yield and conversion. Due to the several steps involved in the extraction of oil which are energy intensive, the cost of biodiesel from microalgal oil is high as compared with that obtained from the plant oils. A sustainable approach for utilizing plant and microalgal oils as feedstocks for biodiesel have been discussed. The emerging cost effective methods in production of biodiesel have been described. The energy return and greenhouse gas emissions from biodiesel have been outlined. Together, the plant oil and microalgal oil can offer potential source of feedstocks for the production of biodiesel. (C) 2013 Elsevier Ltd. All rights reserved.

Towards a sustainable approach for development of biodiesel from plant and microalgae

Microalgae have drawn great attention as promising sustainable source of lipids and carotenoids. Their lipid and carotenoids accumulation machinery can be trigged by the stress conditions such as nutrient limitation or exposure to the damaging physical factors. However, stressful conditions often adversely affect microalgal growth and cause oxidative damage to the cells, which can eventually reduce the yield of the desired products. To overcome these limitations, two-stage cultivation strategies and supplementation of growth-promoting agents have traditionally been utilized, but developing new highly adapted strains is theoretically the simplest strategy. In addition to genetic engineering, adaptive laboratory evolution (ALE) is frequently used to develop beneficial phenotypes in industrial microorganisms during long-term selection under specific stress conditions. In recent years, many studies have gradually introduced ALE as a powerful tool to improve the biological properties of microalgae, especially for improving the production of lipid and carotenoids. In this review, strategies for the manipulation of stress in microalgal lipids and carotenoids production are summarized and discussed. Furthermore, this review summarizes the overall state of ALE technology, including available selection pressures, methods, and their applications in microalgae for the improved production of lipids and carotenoids.

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Microalgae for the production of lipid and carotenoids: a review with focus on stress regulation and adaptation.

Geothermal systems in Iceland: Structure and conceptual models—I. High-temperature areas

Maximizing biomass productivity and cell density of Chlorella vulgaris by using light-emitting diode-based photobioreactor.

Structural analysis of a transform fault-rift zone junction in North Iceland

Diatoms are one major group of algae in oceans that accounts almost half of marine primary food production and have also been identified as a promising candidate for biofuel production for their high level accumulation of lipids. They have gained increasingly attention for their potential applications in pharmaceuticals, cosmetics, nutrient supplements and biofuels. This review aims to summarize the recent advances in diatom lipid study. Chemical structures and bioactivities of different lipid classes are discussed with a focus on valuable lipids such as fatty acids, polar lipids, steroids, and oxylipins from various diatoms species. Further, current extraction and fractionation approaches are compared and recent analytical techniques and methods are also reviewed with an emphasis on lipid class composition and fatty acid profiling. Biosynthetic pathways and key catalyzing enzymes are illustrated for a better understanding of fatty acid metabolism. Past engineering attempts towards generating appropriate diatom strains for lipid production are discussed with examples using mutagenesis, environmental stimulants and genetic modification methods. Some possible future directions and applications of diatom-derived lipids are also proposed.

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Exploring Valuable Lipids in Diatoms

Marine diatoms have recently gained much attention as they are expected to be a promising resource for sustainable production of bioactive compounds such as carotenoids and biofuels as a future clean energy solution. To develop photosynthetic cell factories, it is important to improve diatoms for value-added products. In this study, we utilized UVC radiation to induce mutations in the marine diatom Phaeodactylum tricornutum and screened strains with enhanced accumulation of neutral lipids and carotenoids. Adaptive laboratory evolution (ALE) was also used in parallel to develop altered phenotypic and biological functions in P. tricornutum and it was reported for the first time that ALE was successfully applied on diatoms for the enhancement of growth performance and productivity of value-added carotenoids to date. Liquid chromatography-mass spectrometry (LC-MS) was utilized to study the composition of major pigments in the wild type P. tricornutum, UV mutants and ALE strains. UVC radiated strains exhibited higher accumulation of fucoxanthin as well as neutral lipids compared to their wild type counterpart. In addition to UV mutagenesis, P. tricornutum strains developed by ALE also yielded enhanced biomass production and fucoxanthin accumulation under combined red and blue light. In short, both UV mutagenesis and ALE appeared as an effective approach to developing desired phenotypes in the marine diatoms via electromagnetic radiation-induced oxidative stress.

https://www.mdpi.com/1660-3397/13/10/6138/pdf

Photo-Oxidative Stress-Driven Mutagenesis and Adaptive Evolution on the Marine Diatom Phaeodactylum tricornutum for Enhanced Carotenoid Accumulation

The South Iceland seismic zone is a 20–60 km-wide (north-south) and up to 70 km-long zone of north and north-northeast trending Holocene arrays of en echelon tension fractures. These fracture arrays are related to dextral strike-slip faults buried by Holocene lava flows. In this zone, major destructive earthquake sequences occur at intervals of 45–112 years, the largest events reaching magnitude 7 (Ms). We propose that this seismic zone is located between overlapping rift-zone segments (spreading centers), where the eastern segment has been propagating to the south during the past 3 Ma. We made a finite element study of this configuration with the segments modeled as mode I cracks loaded in tension. The results suggest that the South Iceland seismic zone in general, and the north and north-northeast trending dextral faults in particular, develop in response to the shear stresses generated between the rift-zone segments.

Sigurdur Brynjolfsson

Papers

Maximizing biomass productivity and cell density of Chlorella vulgaris by using light-emitting diode-based photobioreactor.

Structural analysis of a transform fault-rift zone junction in North Iceland

Exploring Valuable Lipids in Diatoms

Photo-Oxidative Stress-Driven Mutagenesis and Adaptive Evolution on the Marine Diatom Phaeodactylum tricornutum for Enhanced Carotenoid Accumulation

Overlapping rift-zone segments and the evolution of the South Iceland Seismic Zone