Application of hydrocyclones for recovery of fine gold from placer material

Alaska and other gold areas have seen a sharp resurgence of placer mining in the last few years. Mines using sluice boxes usually recover gold down to 100 mesh, but recovery of gold finer than this size is a function of particle shape factor, sluice box design and operating parameters. It is felt that a concentrating device is needed to recover gold finer than 100 mesh that may not be recoverable in a sluice box. The device should be capable of processing a large volume of water and solids discharged from the sluice-box. Compound water cyclones, successfully used in the coal processing industry, seem to offer solutions. A system using these devices could recover a concentrate which would be one twenty fifth the size of the original solids in a two stage process. It is not intended to produce a finished product with cyclones, but to reduce bulk so that the reduced concentrate, free of slimes, could further be treated by flotation, gravity methods, or cyanidation to isolate the gold. This report addresses only the application of hydrocyclones for concentrating gold from placer material.Submitted to Mining and Mineral Resources Research Institute, Office of Surface Mining, U.S. Department of Interior, Washington, D.C. Grant No. G519400

Changes in the Information-Intensity of the U.S. Workplace Since 1950: Has Information Technology Made a Difference

information ; technology

Multi-layered Ruthenium-modified Bond Coats for Thermal Barrier Coatings

Diffusional approaches for fabrication of multi-layered Ru-modified bond coats for thermal barrier coatings have been developed via low activity chemical vapor deposition and high activity pack aluminization. Both processes yield bond coats comprising two distinct B2 layers, based on NiAl and RuAl, however, the position of these layers relative to the bond coat surface is reversed when switching processes. The structural evolution of each coating at various stages of the fabrication process has been and subsequent cyclic oxidation is presented, and the relevant interdiffusion and phase equilibria issues in are discussed. Evaluation of the oxidation behavior of these Ru-modified bond coat structures reveals that each B2 interlayer arrangement leads to the formation of α-Al 2 O 3 TGO at 1100°C, but the durability of the TGO is somewhat different and in need of further improvement in both cases

Real-time, in situ measurements of atmospheric optical absorption in the visible via photoacoustic spectroscopy--IV. Visibility degradation and aerosol optical properties in Los Angeles

Aerosol light absorption (babs) has been measured in real-time in Los Angeles with a validated photoacoustic technique, and its impact on visibility degradation has been examined. These measurements were collected during ten days in the summer of 1987 for the Southern California Air Quality Study (SCAQS). Aerosol babs ([lambda] = 514.5 nm) varied from an hourly average value of 7 x 10-6 m-1 in the 3-4 and 4-5 a.m. periods of 13 July to 9 x 10-5 m-1 in the 7-8 a.m. period of both 28 August and 3 September. This babs, which is due solely to elemental carbon (EC) showed a distinct diurnal pattern with low values at night, increasing around sunrise to higher values through mid-afternoon. Comparison of these data with aerosol light scattering data clearly illustrates that the contribution of aerosol light absorption to visibility degradation increases in importance under less polluted conditions. Other urban and rural studies show similar results.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28906/1/0000743.pd

Growth and nutrient absorption of Cape Gooseberry (Physalis Peruviana L.) in soilless culture

"This is an Author's Accepted Manuscript of an article published in [include the complete citation information for the final version of the article as published in the Journal of Plant Nutrition 2015 March, available online at: http://www.tandfonline.com/10.1080/01904167.2014.934474."Cape gooseberry (Physalis peruviana L.) is a solanaceous plant. The growth and time-course of nutrient accumulation of the plant and its partitioning between roots, stems, leaves, and fruits were examined. The study was conducted analyzing two nutrient solutions in soilless culture under greenhouse conditions during two consecutive seasons. The macronutrient contents were analyzed. On average, the yield was 8.9 t.ha(-1). Growth of the plant until 90 d after transplanting obeys an exponential function of time and the relative growth rate for this period was determined. Nitrogen (N) was the element that showed the highest concentration, corresponding to leaves (4.67%), followed by potassium (K) in stems (4.46%). The highest accumulations of N, phosphorous (P), calcium (Ca), and magnesium (Mg) were found in leaves and of K in the stems. Potassium showed the highest nutrient accumulation (29 g.plant(-1)) and the highest specific uptake rate.Torres Rubio, JF.; Pascual Seva, N.; San Bautista Primo, A.; Pascual España, B.; López Galarza, SV.; Alagarda Pardo, J.; Maroto Borrego, JV. (2015). Growth and nutrient absorption of Cape Gooseberry (Physalis Peruviana L.) in soilless culture. Journal of Plant Nutrition. 38(4):485-496. doi:10.1080/01904167.2014.934474S485496384Bellaloui, N., & Brown, P. H. (1998). Plant and Soil, 198(2), 153-158. doi:10.1023/a:1004343031242Bennett, J. P., Oshima, R. J., & Lippert, L. F. (1979). Effects of ozone on injury and dry matter partitioning in pepper plants. Environmental and Experimental Botany, 19(1), 33-39. doi:10.1016/0098-8472(79)90022-4CAUSTON, D. R. (1991). Plant Growth Analysis: The Variability of Relative Growth Rate Within a Sample. Annals of Botany, 67(2), 137-144. doi:10.1093/oxfordjournals.aob.a088112Convenio MAG-IICA (Ministerio de Agricultura y Ganadería. Institución Interamericana de Cooperación para la Agricultura). 2001. The cape gooseberry (Physalis peruvianaL.Physalis edulis). Subprograma de Cooperación Técnica, Ecuador. Available at: http://www.sica.gov.ec/agronegocios/Biblioteca/Convenio%20MAG%20IICA/productos/uvilla_mag.pdf (Accessed July 2007, in Spanish).El-Tohamy, W. A., El-Abagy, H. M., Abou-Hussein, S. D., & Gruda, N. (2009). Response of Cape gooseberry (Physalis peruviana L.) to nitrogen application under sandy soil conditions. Gesunde Pflanzen, 61(3-4), 123-127. doi:10.1007/s10343-009-0211-0Fresquet, J., Pascual, B., López-Galarza, S., Bautista, S., Baixauli, C., Gisbert, J. M., & Maroto, J. V. (2001). Nutrient uptake of pepino plants in soilless cultivation. The Journal of Horticultural Science and Biotechnology, 76(3), 338-343. doi:10.1080/14620316.2001.11511373Heuvelink, E., Bakker, M. J., Elings, A., Kaarsemaker, R. C., & Marcelis, L. F. M. (2005). EFFECT OF LEAF AREA ON TOMATO YIELD. Acta Horticulturae, (691), 43-50. doi:10.17660/actahortic.2005.691.2Leskovar, D. I., & Cantliffe, D. J. (1993). Comparison of Plant Establishment Method, Transplant, or Direct Seeding on Growth and Yield of Bell Pepper. Journal of the American Society for Horticultural Science, 118(1), 17-22. doi:10.21273/jashs.118.1.17Marcelis, L. F. M. (1993). Fruit growth and biomass allocation to the fruits in cucumber. 1. Effect of fruit load and temperature. Scientia Horticulturae, 54(2), 107-121. doi:10.1016/0304-4238(93)90059-yPuente, L. A., Pinto-Muñoz, C. A., Castro, E. S., & Cortés, M. (2011). Physalis peruviana Linnaeus, the multiple properties of a highly functional fruit: A review. Food Research International, 44(7), 1733-1740. doi:10.1016/j.foodres.2010.09.034Radford, P. J. (1967). Growth Analysis Formulae - Their Use and Abuse1. Crop Science, 7(3), 171. doi:10.2135/cropsci1967.0011183x000700030001xRamadan, M. F., & Moersel, J. T. (2007). Impact of enzymatic treatment on chemical composition, physicochemical properties and radical scavenging activity of goldenberry (Physalis peruviana L.) juice. Journal of the Science of Food and Agriculture, 87(3), 452-460. doi:10.1002/jsfa.2728Ramadan, M. F., & Moersel, J.-T. (2009). Oil extractability from enzymatically treated goldenberry (Physalis peruvianaL.) pomace: range of operational variables. International Journal of Food Science & Technology, 44(3), 435-444. doi:10.1111/j.1365-2621.2006.01511.xSalazar, M. R., Jones, J. W., Chaves, B., & Cooman, A. (2008). A model for the potential production and dry matter distribution of Cape gooseberry (Physalis peruviana L.). Scientia Horticulturae, 115(2), 142-148. doi:10.1016/j.scienta.2007.08.015Scholberg, J., McNeal, B. L., Jones, J. W., Boote, K. J., Stanley, C. D., & Obreza, T. A. (2000). Growth and Canopy Characteristics of Field-Grown Tomato. Agronomy Journal, 92(1), 152. doi:10.2134/agronj2000.921152xTrinchero, G. D., Sozzi, G. O., Cerri, A. M., Vilella, F., & Fraschina, A. A. (1999). Ripening-related changes in ethylene production, respiration rate and cell-wall enzyme activity in goldenberry (Physalis peruviana L.), a solanaceous species. Postharvest Biology and Technology, 16(2), 139-145. doi:10.1016/s0925-5214(99)00011-3Turner, A. (1994). Dry Matter Assimilation and Partitioning in Pepper Cultivars Differing in Susceptibility to Stress-induced Bud and Flower Abscission. Annals of Botany, 73(6), 617-622. doi:10.1006/anbo.1994.1077WILLIAMS, R. F. (1946). The Physiology of Plant Growth with Special Reference to the Concept of Net Assimilation Rate. Annals of Botany, 10(1), 41-72. doi:10.1093/oxfordjournals.aob.a083119Zapata, J.L., A. Saldarriaga, M. Londoño, and C. Díaz. 2002. Cape gooseberry Management in Colombia. Antioquia, Colombia: Rionegro, Programa Nacional de Transferencia de Tecnología Agropecuaria - Corpoica Regional Cuatro (in Spanish).Zerihun, A. (2000). Compensatory Roles of Nitrogen Uptake and Photosynthetic N-use Efficiency in Determining Plant Growth Response to Elevated CO2: Evaluation Using a Functional Balance Model. Annals of Botany, 86(4), 723-730. doi:10.1006/anbo.2000.123

Grain Surface Models and Data for Astrochemistry

AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of ∼25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions

Predicting Academic Performance: A Systematic Literature Review

The ability to predict student performance in a course or program creates opportunities to improve educational outcomes. With effective performance prediction approaches, instructors can allocate resources and instruction more accurately. Research in this area seeks to identify features that can be used to make predictions, to identify algorithms that can improve predictions, and to quantify aspects of student performance. Moreover, research in predicting student performance seeks to determine interrelated features and to identify the underlying reasons why certain features work better than others. This working group report presents a systematic literature review of work in the area of predicting student performance. Our analysis shows a clearly increasing amount of research in this area, as well as an increasing variety of techniques used. At the same time, the review uncovered a number of issues with research quality that drives a need for the community to provide more detailed reporting of methods and results and to increase efforts to validate and replicate work.Peer reviewe

Cognitive Invariants of Geographic Event Conceptualization: What Matters and What Refines?

Behavioral experiments addressing the conceptualization of geographic events are few and far between. Our research seeks to address this deficiency by developing an experimental framework on the conceptualization of movement patterns. In this paper, we report on a critical experiment that is designed to shed light on the question of cognitively salient invariants in such conceptualization. Invariants have been identified as being critical to human information processing, particularly for the processing of dynamic information. In our experiment, we systematically address cognitive invariants of one class of geographic events: single entity movement patterns. To this end, we designed 72 animated icons that depict the movement patterns of hurricanes around two invariants: size difference and topological equivalence class movement patterns endpoints. While the endpoint hypothesis, put forth by Regier (2007), claims a particular focus of human cognition to ending relations of events, other research suggests that simplicity principles guide categorization and, additionally, that static information is easier to process than dynamic information. Our experiments show a clear picture: Size matters. Nonetheless, we also find categorization behaviors consistent with experiments in both the spatial and temporal domain, namely that topology refines these behaviors and that topological equivalence classes are categorized consistently. These results are critical steppingstones in validating spatial formalism from a cognitive perspective and cognitively grounding work on ontologies

Orbital Observations of Dust Lofted by Daytime Convective Turbulence

Over the past several decades, orbital observations of lofted dust have revealed the importance of mineral aerosols as a climate forcing mechanism on both Earth and Mars. Increasingly detailed and diverse data sets have provided an ever-improving understanding of dust sources, transport pathways, and sinks on both planets, but the role of dust in modulating atmospheric processes is complex and not always well understood. We present a review of orbital observations of entrained dust on Earth and Mars, particularly that produced by the dust-laden structures produced by daytime convective turbulence called “dust devils”. On Earth, dust devils are thought to contribute only a small fraction of the atmospheric dust budget; accordingly, there are not yet any published accounts of their occurrence from orbit. In contrast, dust devils on Mars are thought to account for several tens of percent of the planet’s atmospheric dust budget; the literature regarding martian dust devils is quite rich. Because terrestrial dust devils may temporarily contribute significantly to local dust loading and lowered air quality, we suggest that martian dust devil studies may inform future studies of convectively-lofted dust on Earth