Layered Double Hydroxides: Potential Release-on-Demand Fertilizers for Plant Zinc Nutrition.

PubMed

López-Rayo, Sandra; Imran, Ahmad; Bruun Hansen, Hans Chr; Schjoerring, Jan K; Magid, Jakob

2017-10-11

A novel zinc (Zn) fertilizer concept based on Zn-doped layered double hydroxides (Zn-doped Mg-Fe-LDHs) has been investigated. Zn-doped Mg-Fe-LDHs were synthesized, their chemical composition was analyzed, and their nutrient release was studied in buffered solutions with different pH values. Uptake of Zn by barley (Hordeum vulgare cv. Antonia) was evaluated in short- (8 weeks), medium- (11 weeks), and long-term (28 weeks) experiments in quartz sand and in a calcareous soil enriched with Zn-doped Mg-Fe-LDHs. The Zn release rate of the Zn-doped Mg-Fe-LDHs was described by a first-order kinetics equation showing maximum release at pH 5.2, reaching approximately 45% of the total Zn content. The Zn concentrations in the plants receiving the LDHs were between 2- and 9.5-fold higher than those in plants without Zn addition. A positive effect of the LDHs was also found in soil. This work documents the long-term Zn release capacity of LDHs complying with a release-on-demand behavior and serves as proof-of-concept that Zn-doped Mg-Fe-LDHs can be used as Zn fertilizers.

A Decolonizing Encounter: Ward Churchill and Antonia Darder in Dialogue. Counterpoints: Studies in the Postmodern Theory of Education. Volume 430

ERIC Educational Resources Information Center

Orelus, Pierre W., Ed.

2012-01-01

"A Decolonizing Encounter" examines the effects of western colonialism on historically marginalized and colonized populations living both in the West and the "third world". Specifically, it explores crucial issues such as the decolonizing of schools and communities of color; the decentralization of power of the capitalist and…

Student trajectories in physics: the need for analysis through a socio-cultural lens

NASA Astrophysics Data System (ADS)

Zapata, Mara

2010-09-01

An analysis of student connections through time and space relative to the core discipline of physics is attempted, as viewed through the lens of actor-network-theory, by Antonia Candela. Using lenses of cultural realities, networks, and perceived power in the discourse of one specific university in the capital city of Mexico and one undergraduate physics classroom, the trajectories and itineraries of students are analyzed, relative to a physics professor's pedagogical practices. This ethnographic study then yields comparisons between Mexican undergraduate students and students from the United States. Actor network theory recognizes that the symbiotic relationship existing between an actor and a continuum of space and time is defined by the symbiotic yet interdependent relationships and networks of practice (Lemke in Downward causation: Minds, bodies, and matter 2000). As part of this study and in line with actor-network-theory, human actors and non-human participants were viewed in relation to how subjects acted and were acted upon within networks of practice. Through this forum I reflect on this work with particular focus on the issues of situatedness of actors from a sociocultural perspective and how established networks viewed within this perspective frame and subsequently impact student trajectories and itineraries. In essence I argue for a need to look at a myriad of further complexities driving the symbiotic relationships being analyzed.

Discoveries, Achievements, and Personalities of the Women Who Evolved the Harvard Classification of Stellar Spectra: Williamina Fleming, Antonia Maury, and Annie Jump Cannon.

NASA Astrophysics Data System (ADS)

Welther, Barbara L.

2010-01-01

In 1915, the year in which Cannon (1863-1941) completed her work of classifying stars for The Henry Draper Catalogue, she published a popular article entitled, "Pioneering in the Classification of Stellar Spectra.” In it she gave a historical overview of the field in nineteenth-century Europe. She also detailed the context for the structured and routine work she and her colleagues had been engaged in for several years in America. The motivators that kept Cannon and the other women working diligently were the exciting prospect of making new discoveries, the reward of publicity, and their own personal pride. Usually, the discoveries consisted of finding a peculiar type of spectrum and identifying the star as a nova or variable. Such a discovery often resulted in a newspaper headline about the star and a story about the discoverer. This paper will outline the contributions each woman made to the classification system, her style of working, the papers she wrote and published, and the rewards she reaped for her dedication to the field.

Anterior uveal spindle cell tumor in a cat.

PubMed

Evans, Paige M; Lynch, Gwendolyn L; Dubielzig, Richard R

2010-11-01

To describe a case of anterior uveal spindle cell tumor in a cat with features similar to spindle cell tumor of blue eyed dogs. A 10-year-old female spayed domestic short-haired cat was referred for an iris mass OS. The mass was solitary, nodular, nonpigmented, located medially, and causing dyscoria. A diagnosis of a benign epithelial tumor was suggested by a FNA of the mass. The cat was lost to follow-up for 2 years, after which time she re-presented with glaucoma, blindness and grossly evident iridal mass enlargement OS. Transconjunctival enucleation was performed and the globe submitted for histopathology. Histopathology of the enucleated globe revealed the superior iris to be infiltrated and effaced by a large population of neoplastic spindle cells. The cells were arranged in streams and bundles and exhibited Antoni-A and Antoni-B tissue patterns, which are characteristic of Schwann cell tumors. Mitotic figures were rare and cellular pleomorphism moderate. Immunohistochemical staining was positive for S-100 protein and glial fibrillary acidic protein (GFAP), and negative for Melan-A. Interestingly, there was no histological evidence of glaucoma. Based on its histopathologic characteristics, this iris tumor was diagnosed as a Schwann cell variant of a peripheral nerve sheath tumor (PNST) closely resembling the spindle cell tumor of blue-eyed dogs. Anterior uveal PNST has not been previously reported in cats to the authors' knowledge. The presence of Antoni type A and type B tissue patterns along with immunohistochemical staining may facilitate a diagnosis of PNST and rule out malignant melanoma. © 2010 American College of Veterinary Ophthalmologists.

From Greenhouse to Icehouse: Evidence of Climatic Changes Across the Marine Eocene-Oligocene Transition From the Massignano GSSP Section (Central Italy)

NASA Astrophysics Data System (ADS)

Coccioni, R.; Marsili, A.; Montanari, A.

2004-12-01

The transition from global "greenhouse" conditions of the early and middle Eocene to global "icehouse" conditions of the early Oligocene marks a turning point in Cenozoic Earth history which was marked by reorganization of global ocean circulation patterns and significant turnovers in the marine and terrestrial biota (Prothero et al., 2003) and led to the development of the first East Antarctic ice-sheet, close to the Eocene/Oligocene boundary (33.7 Ma). The Massignano GSSP for the Eocene/Oligocene boundary (Premoli Silva & Jenkins, 1993), exposed in an abandoned quarry in the Monte Conero area, on the Adriatic coast of central Italy, was investigated at high-resolution in order to provide evidence for climatic changes across the marine Eocene-Oligocene transition. The Massignano section is 23-m thick and consists of alternating reddish/greenish-grey marls and calcareous marls with several biotite-rich levels of volcanic origin which were deposited in a lower bathyal depositional setting, at a paleodepth of 1000-2000 m (Coccioni & Galeotti, 2003). A complete geological record of 3 myr (from 36.2 to 33.2 Ma according to the time scale of Berggren et al., 1995) is preserved which spans the interval from the latest Eocene to the early Oligocene, from Chron C16n to C13n (Bice & Montanari, 1988; Lowrie & Lanci, 1994), and is provided by an accurate calibration of bio- and geochemical events. Cosmic signatures are also recorded in the Massignano section (Montanari et al., 1993) where three impactoclastic, iridium-rich layers occurs in the middle-lower part of the succession (Montanari et al., 1988, 1993; Bodeselitsch et al., 2004). They are possibly linked to the Popigai and Chesapeake Bay impacts and related to a comet shower over a duration of 2.2 myr (Farley et al., 1998). Calcareous nannofossil and foraminiferal assemblages (Coccioni et al., 2000; Spezzaferri et al., 2002), dinoflagellate cyst palynology (Brinkhuis & Biffi, 1993), ostracod faunas (Dall'Antonia et al

The Supreme Court retreats another step on abortion.

PubMed

Rosoff, J I

1990-01-01

The 1973 "Roe v. Wade" decision is being further dismantled by the Supreme Court. However, in recent decisions, the new Court majority (except Justice Antonia Scalia) seems to say that there is a constitutional right to abortion. The "Hodgson v. Minnesota" and "Ohio v. Akron Center for Reproductive Health" decisions addressed difficult topics; the ability of a minor to give informed consent; and the rights of parents with regard to minor children. In most circumstances, medical treatment of children must be authorized by a guardian. However, in many states, children may seek treatment for pregnancy, substance abuse, sexually transmitted diseases, and psychological disturbances. In "Planned Parenthood of Central Missouri v. Danforth" and "Bellati v. Baird," the Supreme Court ruled that constitutional protection of abortion could not be conditioned by age, and that parents could not say no to their daughter's wish to have an abortion. If a girl did not want to notify her parent, she could go to a judge instead. The Court never ruled on whether parental notification was constitutional, or whether 1 parent (and, if so, which) or both had to be notified. All of these issues were addressed in "Hodgson" and "Ohio" in ways that were damaging to the welfare and rights of women. In "Hodgson," the Court decided that states may require both biological parents to be notified as long as they have judicial bypass. In "Ohio," the Court approved the state's complicated legal judicial bypass proceedings. It also ruled that the proceedings do not have to be anonymous, just confidential. The reasoning behind the decisions is ambiguous and contradictory. Justice Sandra Day O'Connor agreed that the Minnesota law is very stringent. She said that it was "unreasonable when one considers that only 1/2 of the minors in the State of Minnesota reside with both biological parents." The Court's majority explained that a 48-hour waiting period between the notification and the abortion might place

Optical space weathering on Vesta: Radiative-transfer models and Dawn observations

NASA Astrophysics Data System (ADS)

Blewett, David T.; Denevi, Brett W.; Le Corre, Lucille; Reddy, Vishnu; Schröder, Stefan E.; Pieters, Carle M.; Tosi, Federico; Zambon, Francesca; De Sanctis, Maria Cristina; Ammannito, Eleonora; Roatsch, Thomas; Raymond, Carol A.; Russell, Christopher T.

2016-02-01

Exposure to ion and micrometeoroid bombardment in the space environment causes physical and chemical changes in the surface of an airless planetary body. These changes, called space weathering, can strongly influence a surface's optical characteristics, and hence complicate interpretation of composition from reflectance spectroscopy. Prior work using data from the Dawn spacecraft (Pieters, C.M. et al. [2012]. Nature 491, 79-82) found that accumulation of nanophase metallic iron (npFe0), which is a key space-weathering product on the Moon, does not appear to be important on Vesta, and instead regolith evolution is dominated by mixing with carbonaceous chondrite (CC) material delivered by impacts. In order to gain further insight into the nature of space weathering on Vesta, we constructed model reflectance spectra using Hapke's radiative-transfer theory and used them as an aid to understanding multispectral observations obtained by Dawn's Framing Cameras (FC). The model spectra, for a howardite mineral assemblage, include both the effects of npFe0 and that of a mixed CC component. We found that a plot of the 438-nm/555-nm ratio vs. the 555-nm reflectance for the model spectra helps to separate the effects of lunar-style space weathering (LSSW) from those of CC-mixing. We then constructed ratio-reflectance pixel scatterplots using FC images for four areas of contrasting composition: a eucritic area at Vibidia crater, a diogenitic area near Antonia crater, olivine-bearing material within Bellicia crater, and a light mantle unit (referred to as an ;orange patch; in some previous studies, based on steep spectral slope in the visible) northeast of Oppia crater. In these four cases the observed spectral trends are those expected from CC-mixing, with no evidence for weathering dominated by production of npFe0. In order to survey a wider range of surfaces, we also defined a spectral parameter that is a function of the change in 438-nm/555-nm ratio and the 555-nm reflectance

CO2 Enhanced Oil Recovery from the Residual Zone - A Sustainable Vision for North Sea Oil Production

NASA Astrophysics Data System (ADS)

Stewart, Jamie; Haszeldine, Stuart; Wilkinson, Mark; Johnson, Gareth

2014-05-01

conventional oil. The application of CO2EOR to ROZ enables a significant contribution to a field's recoverable reserves [3]. This work identifies for the first time the plays of geological conditions that create naturally occurring residual oil zones in the United Kingdom Continental Shelf. We present a screening workflow to identify such zones and a methodology for assessing the resource potential and CO2 storage capacity for a number of different fields. Lastly we examine the economic consequences on CO2 storage of the incremental oil produced, and the carbon balance life-cycle. [1] Melzer, S., Koperna, G., Kuuskraa, V. 2006. The Origin and Resource Potential of Residual Oil Zones. SPE Annual and Technical Conference, San Antonio, Texas, Society. [2] Koperna, G., Melzer. S.L., Kuuskraa, V. 2006. Recovery of Oil Resources From the Residual and Transitional Oil Zones of the Permian Basin.. SPE Annual Technical Conference, San Antonia, Texas. Society of Petroleum Engineers. [3] Advanced Resources International, 2005. Assessing Technical and Economic Recovery of Residual Oil Zones. U.S Department of Energy.

Obituary: Edwin E. Salpeter (1924-2008)

NASA Astrophysics Data System (ADS)

Trimble, Virginia; Terzian, Yervant

2009-12-01

Edwin E. Salpeter, who died 26 November 2008 at his home in Ithaca, NY, belonged to the "second wave" of Jewish scientific refugees from Nazi-dominated Europe, those who left as children just before the onset of WWII and so completed their educations elsewhere. Salpeter was born in Vienna on 3 December 1924, and arrived with his family in Australia in 1939, his father was a physicist and a close friend of Erwin Schrodinger. In Australia, he finished high school, and he entered the University of Sydney at the early age of 16. He received his BS and MSc degrees in physics and mathematics from the University of Sydney, before moving on to a PhD from the University of Birmingham in 1948, for work with Rudolf Peierls on the electrodynamic self-energy of the electron, the first of more than 380 inventoried publications. He had chosen Birmingham over Cambridge or Oxford because of Peierls, and then chose Cornell over Princeton because of Hans Bethe's presence there. His autobiography describes those as two of his very best decisions ever. Marrying psychobiology student Miriam (Mika) Mark less than a year after arriving at Cornell was surely the third, and they remained in Ithaca the rest of their lives, eventually collaborating on some projects in neurobiology before her death in 2000. Their household was a secular one, but (Ed told a colleague) their two daughters received a basic Jewish education "just in case." Daughter Shelley Salpeter and her son Nicholas Buckley were also collaborators with Salpeter on 21st century projects in meta-analysis, epidemiology, and other statistics-heavy problems in biomedicine. Ed Salpeter is survived by his second wife, Antonia (Lhamo) Shouse. Astronomers may be interested to learn that the Cornell press release announcing his death was prepared by Lauren Gold, daughter of Thomas Gold (and Carrie Gold) the co-author of the steady state theory. Apparently, Ed's father Jakob Salpeter late in life considered the anisotropy reported in the

Obituary: E. Dorrit Hoffleit, 1907-2007

NASA Astrophysics Data System (ADS)

Trimble, Virginia

2007-12-01

next year as a research assistant (later research associate) at Harvard College Observatory, then directed by Harlow Shapley, about whom her opinion was much warmer than that expressed by Cecilia Payne Gaposchkin. Dorrit's immediate supervisor at Harvard was Henrietta Swope, daughter of the President of General Electric, and eventually best known for work at Mount Wilson Observatory with Walter Baade on variable stars in the Magellanic Clouds, published in papers that continued to appear long after Baade's death. Hoffleit's first ten papers were also on variable stars and appeared in Harvard Observatory publications. But the MA she completed in 1932 was on the light curves of meteors and was published in the Proceedings of the United States National Academy of Sciences. By this time, Dorrit had established a work pattern that was to persist right up to retirement - at least 40 hours per week on whatever the current boss thought she should be doing, and another 20 or so on other astronomical research that interested her. Hffleit had supposed that an MA would be her highest degree, but Shapley urged her to go on for a PhD, with, it would seem, a bit of urging on both sides from Bart Bok, who informed her that "if God recommends that you do something, it is your duty to do it." The thesis (PhD 1938) was on yet a third topic, spectroscopic parallaxes. This means determining the luminosities of stars, hence their distances, from line width and ratio diagnostics in their spectra. The pioneer was Antonia Maury, whose insights were not appreciated by Shapley's predecessor, E. C. Pickering. Another valuable Hoffleit mentor was Ernst Öpik, on a three-month visit to Harvard in 1934, from whom Dorrit learned stellar statistics and half a dozen other things. The thesis also provided her "break out" paper into the Astrophysical Journal (on CN as a giant/dwarf discriminator). Hoffleit began to branch out into astrometry, comets, and other parts of astronomy and, starting in 1941