Length to diameter ratio and row number effects in short pin fin heat transfer

The relative effects of pin length to diameter ratio and of pin row geometry on the heat transfer from pin fins, was determined. Array averaged heat transfer coefficients on pin and endwall surfaces were measured for two configurations of staggered arrays of short pin fins (length to diameter ratio of 4). One configuration contained eight streamwise rows of pins, while the other contained only four rows. Results showed that both the 8-row and the 4-row configurations for an L sub p/D of 4, exhibit higher heat transfer than in similar tests on shorter pin fns (L sub p/D of 1/2 and 2). It was also found that for this L sub p/D ratio, the array averaged heat transfer was slightly higher with eight rows of staggered pins than with only four rows

Chapter 9: Aquatic Macroinvertebrates, Section A: Aquatic Macroinvertebrates (Exclusive of Mosquitoes)

Final Report. Excerpt (Chapter 9, Section A) from The Des Plaines River Wetlands Demonstration Project, Volume II, Baseline Survey, edited by Donald L. Hey and Nancy S. PhilippiReport issued on: October 1985INHS Technical Report prepared for Wetlands Research, Inc

Chitin and Chitosan: Sustainable, Medically Relevant Biomaterials

The polysaccharides chitin and chitosan are made up of monomer units of the amino sugars D-glucosamine and N-acetyl-D-glucosamine. The ratio of these two monomers dictates whether the polysaccharide is considered chitin or chitosan. Both polymers have unique properties and have uses in several diverse applications. In nature, chitin and chitosan primarily play a structural role. When purified from their producing organism, these polymers exhibit useful structural, chemical and biological properties. Chitin and chitosan have been used in several applications including biomedicine, food additives, cosmetics, and more. The charged chitosan polymer is especially effective in biomedical applications, as it has been demonstrated to possess antimicrobial properties. This review explores the properties of chitin and chitosan and how these biopolymers are used in a variety of healthcare and other applications

From Beverages to Biofuels: The Journeys of Ethanol-Producing Microorganisms

Microbial fermentation for bio-based products is quickly becoming an integral component of the world infrastructure, as the processes encompassing the synthesis of these natural products becomes more efficient and cost effective to compete with existing commodities. Bioethanol is currently one of the most desired fermentation products, as this constituent can be applied to multiple uses in not only contributing to the more traditional routes of beer brewing and winemaking, but also in the foundation for green fuel sources. By optimizing yields, the innovative processes could be applied towards engineering more rapid and productive biomanufacturing. In order to achieve these goals, we as researchers must understand the underlying principles and intricate networks that play a role within the microenvironment and also on the cellular level in key fermentative microbes such as Saccharomyces cerevisiae and Zymomonas mobilis. In-depth pathway analysis could lead to the development of more favorable metabolic outcomes. This review focuses on the key metabolic networks and cellular frameworks in these model organisms, and how biosynthesis of ethanol yields can be optimized throughout the fermentation process

Pliocene Marine Transgressions of Northern Alaska: Circumarctic Correlations and Paleoclimatic Interpretations

At least three marine transgressions of Piliocene age are recorded by littoral to inner-shelf sediments of the Gubik Formation, which mantles the Arctic Coastal Plain of northern Alaska. The three recognized transgressions were eustatic high sea levels that, from oldest to youngest, are informally named the Colvillian, Bigbendian, and Fishcreekian transgressions. The geochronology is based up amino acid geochemistry, paleomagnetic studies, vertebrate and invertebrate paleontology, and strontium isotope age estimates. Pollen, plant macrofossils, and marine vertebrate and inventebrate remains indicate that these transgressions occurred when the Arctic was at least intermittently much warmer than it is now. The Colvillian transgression took place at sometime between 2.48 and 2.7 Ma, when adjacent coastal areas supported an open boreal forest or spruce-birch-woodland with scattered pine and rare fir and hemlock. The Bigbendian transgression occurred about 2.48 Ma. Climate conditions were probably slightly cooler than during the Colvillian transgression, but probably too warm for permafrost and too warm for even seasonal sea ice in the region. Nearby vegetation was open spruce-birch woodland or parkland, possibly with rare scattered pine. The Fishcreekian transgression took place sometime between 2.14 and 2.48 Ma and was also characterized by warm marine conditions without sea ice. During the waning stages of this transgression, however, terrestrial conditions were relatively cool, and coastal vegetation was herbaceous tundra with scattered larch trees in the vicinity. Other marine units from this time period occur around the Arctic Basin. The three oldest transgressions recognized from the Seward Peninsula may be broadly correlated with the three Piliocene transgresions of the Arctic Coastal Plain. The Tusatuvayam beds in Kamchatka possibly correlate with one of the two younger transgressions of northern Alaska. The non-marine Worth Point Formation of Banks Island may be younger than all three of the transgressions of the Arctic Coastal Plain, and marine sediment of the Beaufort Formation on Meighen Island is slightly older than the Colvillian transgression. None of the Piliocene marine units on Baffin Island can be confidently correlated with the high sea level events of northern Alaska. The upper Kap Kobenhavn Formation and the upper Loden Elv Formation of Greenland most likely correlate with the Fishcreekian transgression.Key words: Arctic, amino acids, Pliocene, Pleistocene, paleoclimate, marine transgressions, sea level, Alaska, Gubik FormationRÉSUMÉ. Au moins trois transgressions marines datant du pliocène sont inscrites dans les sediments allant du littoral à l’interieur de la plateforme de la formation Gubik, qui recouvre la plaine côtière arctique de l’Alaska septentrional. Les trois transgressions reconnues correspondent à des fortes remontées du niveau de la mer et ont reçu, dans l’ordre chronologique, les noms informels de formations "colvillienne", "bigbendienne" et "fishcreekienne". La géochronologie s’appuie sur la géochimie des acides aminés, des études paléomagnétiques, la paléontologie de vertébrés et d’invertébrés ainsi que sur des estimations de datation à l’isotope du strontium. Les pollens, les macrofossiles végétaux ainsi que les restes de vertébrés et d’invertébrés marins indiquent que ces transgressions se sont produites alors que l’Arctique  était, pour le moins de façon intermittente, beaucoup plus chaud que maintenant. La transgression colvillienne a eu lieu à un moment donné entre 2,48 et 2,7 Ma, alors que les zones côtières adjacentes supportaient une forêt boréale ouverte ou des bois d’épinettes-bouleaux avec quelques pins éparpillés et de rares sapins et pruches. La transgression bigbendienne a eu lieu aux alentours de 2,48 Ma. Les conditions climatiques étaient probablement un peut plus froides que durant la transgression colvillienne, mais aussi probablement trop chaudes pour le pergélisol et en tout cas trop chaudes pour permettre la création d’une banquise - même saisonnière - dans la region. La végétation proche consistait en des bois ou des forêts-parcs d’épinettes-bouleaux avec peut-êtrequelques pins éparpillés. La transgression fishcreekienne a pris place à un moment donné entre 2,14 et 2,48 Ma et a aussi été caractérisée par des conditions marines chaudes sans banquise. Durant le declin de cette transgression cependant, les conditions climatiques terrestres étaient relativement froides et la végétation côtière se composait de toundra herbacée semée de mélèzes aux alentours. D’autres unites marines datant de cette période se trouvent autour du bassin de l’Arctique. Les trois plus anciennes transgressions établies dans la péninsule Seward peuvent être dans l’ensemble corrélées avec les trois transgressions du pliocène de la plaine côtière arctique. Les couches Tusatuvayam dans la Kamchatka sont peut-être corréler avec l’une des deux transgressions les plus jeunes de l’Alaska septentrional. La formation non marine Worth Point de l’île de Banks est peut-être plus jeune que les trois transgressions de la plaine côtière arctique et les sediments marins de la formation de Beaufort dans l’île Meighen sont légèrement plus anciens que la transgression colvillienne. On ne peut avec certitude corréler aucune des unités marines du pliocène sur l’île de Baffin avec les événements eustatiques qui ont amené une  élévation du niveau marin dans l’Alaska septentrional. La partie supérieure de la formation Kap Kobenhavn et celle de la formation Loden Elv du Groenland sont probablement à corréler avec latransgression fishcreekienne.Mots clés: Arctique, acides aminés, pliocène, pléistocène. paléoclimat, transgressions marines, niveau de la mer, Alaska, formation de Gubi

David Moody Hopkins (1921-2001)

David M. Hopkins, a Quaternary geologist widely known for his broad-ranging studies of the Bering Land Bridge region ("Beringia"), passed away at his home in Menlo Park, California, on November 2, 2001. Dave was a longtime member of Alaskan units of the U.S. Geological Survey (USGS). In search of a deeper understanding of Beringia, he became a pioneer in interdisciplinary research and in collaborative research with Russian investigators. Following his retirement from the USGS in 1985, Dave became director of the Alaskan Quaternary Center and Professor of Quaternary Studies at the Fairbanks campus of the University of Alaska. During the 57 years of his professional career, he was a mentor, friend, and source of inspiration to several generations of Arctic scholars. ... After graduating from the University of New Hampshire with a bachelor's degree in Geology in 1942, he joined the USGS and began graduate studies at Harvard University. Dave spent his initial field seasons with the USGS in southern regions of Alaska, where he investigated strategic minerals, engineering geology, and other aspects of geology that were considered essential to the ongoing war effort. In 1944, he was inducted into the Army and assigned to carry out meteorological observations at Cold Bay, situated at the tip of the Alaska Peninsula. Following his discharge, Dave resumed graduate studies at Harvard and field work with the USGS. He obtained an M.S. degree in Geology (1948) and a Ph.D. in Quaternary Geology (1955) from Harvard University. In 1947, Dave began geological investigations on the Seward Peninsula under the permafrost program of the USGS Alaska Terrain and Permafrost Section (which later became the Branch of Alaskan Geology). ... In 1948, he initiated a productive collaboration with the botanist Robert Sigafoos. Their seminal publications on the interactions of permafrost, soil, and vegetation on the Seward Peninsula are considered classics today. Dave also began a long-term collaboration with the archeologist Louis Giddings on dating and reconstructing the paleoecology of prehistoric village sites and other early human habitations in northwestern Alaska. ... Dave's investigations of elevated and submerged gold-bearing beaches at Nome during the 1950s initiated his long-lasting interest in the sea-level history of Beringia and the paleoecology of parts of the Bering platform that are submerged today. ... Dave's broadening interests in the paleoecology of Beringia led to increasing contacts with Russian colleagues that developed into a fruitful, 40-year collaboration across the Bering Strait. ... After Dave's retirement from the USGS, he began a second career of teaching and research as Distinguished Professor of Quaternary Studies at the University of Alaska at Fairbanks (UAF). ... As a direct result of Dave's broad-ranging research on the northern Seward Peninsula, the U.S. National Park Service (NPS) set aside much of his former field area as the Bering Land Bridge National Preserve. ... Dave's scientific influence encompasses such diverse fields as bedrock geology, marine geology, paleontology, limnology, hydrology, ecology, archeology, and paleoclimatology - the topics of his more than 200 refereed papers and abstracts. Numerous awards and commendations from the USGS and other scientific organizations recognized his contributions. ... During his highly productive career, Dave always found time to advise and encourage younger colleagues and students. ... We shall all miss his warmth, his humor, and his infectious passion for Beringia, but his legacy of inspired research and interdisciplinary scholarship will be enduring. ..

Geothermal reservoir engineering research

The Stanford University research program on the study of stimulation and reservoir engineering of geothermal resources commenced as an interdisciplinary program in September, 1972. The broad objectives of this program have been: (1) the development of experimental and computational data to evaluate the optimum performance of fracture-stimulated geothermal reservoirs; (2) the development of a geothermal reservoir model to evaluate important thermophysical, hydrodynamic, and chemical parameters based on fluid-energy-volume balances as part of standard reservoir engineering practice; and (3) the construction of a laboratory model of an explosion-produced chimney to obtain experimental data on the processes of in-place boiling, moving flash fronts, and two-phase flow in porous and fractured hydrothermal reservoirs

Applications of Polyhydroxyalkanoates in the Medical Industry

The bio-based, biodegradable family of polymers, polyhydroxyalkanoates (PHA), is an attractive candidate for an environmentally friendly replacement of petroleum-based plastics in many applications. In the past decade, many groups have examined the biodegradability and biocompatibility of PHA in cell culture systems or in an animal host. Findings suggest that PHA is a suitable material for fabrication of resorbable medical devices, such as sutures, meshes, implants, and tissue engineering scaffolds. The degradation kinetics of some PHA polymers is also suggestive of drug release applications. In this review, we examine the progress, potential applications, challenges and outlook in the medical polyhydroxyalkanoate field

The Potential of Polyhydroxyalkanoate Production from Food Wastes

Background and objective: Over 1 billion tons of foods are wasted every year (not consumed by humans or animals). Most of this waste ends up in landfills. As the global population increases, mankind must look for more sustainable means of living. A recently popular idea is the use of organic wastes as carbon feedstocks for fermentation that produces value added products. Polyhydroxyalkanoates are a family of bio-based, biodegradable polymers that can be produced in large quantities using food and food processing wastes as the main feedstocks. In many cases, biocatalysts have been engineered to efficiently use these waste compounds to produce large quantities of useful intracellular polyhydroxyalkanoates.Results and conclusion: In the current study, various polyhydroxyalkanoates were produced; each with different thermal and mechanical characteristics useful for different applications. If polyhydroxyalkanoate production facilities are established next to food waste accumulation sites (e.g., large landfills), potentials for the economical and sustainable polyhydroxyalkanoate production sound promising.Conflict of interest: The authors declare no conflict of interest