Humic acids: Their detergent qualities and potential uses in pollution remediation     

Ray von Wandruszka 《Geochemical transactions》2000,1(1):10-6

Humic acids are amphiphilic species whose behavior in aqueous solution suggests that they form pseudomicelles–aggregates akin to the micelles familiar from synthetic surfactant chemistry. It is thought that humic pseudomicelles can be formed by both intramolecular coiling and intermolecular association, depending on the molecular weight, structural characteristics, and polydispersity of the humic acid in question. The process does not feature a critical micelle concentration. Experimental evidence indicates that metal ions enhance the detergent character of dissolved humic acid by facilitating the coiling and folding of the polymer chains. A recently conceived alternative model suggests that humic acids consist of relatively small subunits that associate through weak molecular interactions. This view appears to run counter to certain experimental observations, but deserves careful attention. The strong association between metal ions and solid humic acid makes it possible to use an inexpensive commercial grade for the decontamination of polluted water. A continuous elution process through a column packed with humic acid allows for the removal of both heavy metals and organic xenobiotics from aqueous solution.  相似文献   

The Ultimate CCD for Laser Guide Star Wavefront Sensing on Extremely Large Telescopes     

James W. Beletic  Sean Adkins  Barry Burke  Robert Reich  Bernie Kosicki  Vyshnavi Suntharalingham  Charlie Bleau  Ray DuVarney  Richard Stover  Jerry Nelson  Francois Rigaut 《Experimental Astronomy》2005,19(1-3):103-109

All of the extremely large telescopes (ELTs) will utilize sodium laser guide star (LGS) adaptive optics (AO) systems. Most of these telescopes plan to use the Shack-Hartmann approach for wavefront sensing. In these AO systems, the laser spots in subapertures at the edge of the pupil will suffer from spot elongation due to the 10 km extent of the sodium layer and the large separation from the projection laser. This spot elongation will severely degrade the performance of standard geometry wavefront sensing systems. In this paper, we present a CCD with custom pixel morphology that aligns the pixels of each subaperture with the radial extension of the LGS spot. This CCD design will give better performance than a standard geometry CCDs for continuous wave lasers. In addition, this CCD design is optimal for a pulsed sodium laser. The pixel geometry enables each subaperture to follow a laser pulse traversing the sodium layer, providing optimal sampling of a limited number of detected photons. In addition to novel pixel layout, this CCD will also incorporate experimental JFET sense amplifiers and use CMOS design approaches to simplify the routing of biases, clocks and video output. This CCD will attain photon-noise limited performance at high frame rates, and is being incorporated in the plans for the Thirty Meter Telescope (TMT).  相似文献   

Nonlinear wave-wave interactions and wedge waves     

RayQ.Lin WillPerrie 《中国海洋湖沼学报》2005,23(2):129-143

A tetrad mechanism for exciting long waves, for example edge waves, is described based on nonlinear resonant wave-wave interactions. In this mechanism, resonant interactions pass energy to an edge wave,from the three participating gravity waves. The estimated action flux into the edge wave can be orders of magnitude greater than the transfer fluxes derived from other competing mechanisms, such as triad interactions. Moreover, the numerical results show that the actual transfer rates into the edge wave from the three participating gravity waves are two- to three- orders of magnitude greater than bottom friction.  相似文献   

The lunar farside: The nature of highlands east of Mare Smythii     

Pamela E. Clark  B. Ray Hawke 《Earth, Moon, and Planets》1991,53(2):93-107

Available lunar orbital data were studied in detail to determine the nature and origin of geochemical variation in a portion of the farside highlands east of the Smythii basin. Such data exist for the elements Al, Mg, Fe, Ti, and Th (Clark and Hawke, 1981; Davis, 1980; Metzger et al., 1977). As in our previous studies (Clarke and Hawke, 1981, 1987), averages and ranges of concentrations for these elements are calculated and correlated for photogeologically defined units associated with features such as Babcock, King, Al-Khwarezmi, Langemak, Pasteur, and Sklodowska and with the region as a whole. In addition, comparisons are made between this and other highland regions which have been investigated by other workers in a similar manner (Andre et al., 1977; Haines et al., 1978; Maxwell and Andre, 1981). The region is shown to be distinctively enriched in the anorthositic end-members of the ANT-suite. Anomalies which have been reported for this region (Hawke et al., 1985) are confirmed by this study. An area south of Pasteur shows enrichment in some mafic components, giving evidence for the presence of buried mare basalt, and lending support to the hypothesis that volcanic activity may be fairly widespread even in the farside highlands. The units just southeast of Mare Smythii appear to be geochemically related to the area partly surrounding the Smythii on the west (Clark and Hawke, 1987). Considerable geochemical heterogeneity exists in this area, as in areas of the nearside highlands (Clark and Hawke, 1981, 1982, 1987; Hawke et al., 1985).  相似文献   

Highly heterogeneous Precambrian basement under the central Deccan Traps, India: Direct evidence from xenoliths in dykes   总被引：1，自引：0，他引：1  

Ranjini Ray  Anil D. Shukla  Hetu C. Sheth  Jyotiranjan S. Ray  Raymond A. Duraiswami  Loyc Vanderkluysen  Chandramohan S. Rautela  Jyotirmoy Mallik 《Gondwana Research》2008,13(3):375-385

Crustal or mantle xenoliths are not common in evolved, tholeiitic flood basalts that cover huge areas of the Precambrian shields. Yet, the occasional occurrences provide the most direct and unequivocal evidence on basement composition. Few xenolith occurrences are known from the Deccan Traps, India, and inferences about the Deccan basement have necessarily depended on geophysical studies and geochemistry of Deccan lavas and intrusions. Here, we report two basalt dykes (Rajmane and Talwade dykes) from the central Deccan Traps that are extremely rich in crustal xenoliths of great lithological variety (gneisses, quartzites, granite mylonite, felsic granulite, carbonate rock, tuff). Because the dykes are parallel and only 4 km apart, and only a few kilometres long, the xenoliths provide clear evidence for high small-scale lithological heterogeneity and strong tectonic deformation in the Precambrian Indian crust beneath. Measured ⁸⁷Sr/⁸⁶Sr ratios in the xenoliths range from 0.70935 (carbonate) to 0.78479 (granite mylonite). The Rajmane dyke sampled away from any of the xenoliths shows a present-day ⁸⁷Sr/⁸⁶Sr ratio of 0.70465 and initial (at 66 Ma) ratio of 0.70445. The dyke is subalkalic and fairly evolved (Mg No. = 44.1) and broadly similar in its Sr-isotopic and elemental composition to some of the lavas of the Mahabaleshwar Formation. The xenoliths are comparable lithologically and geochemically to basement rocks from the Archaean Dharwar craton forming much of southern India. As several lines of evidence suggest, the Dharwar craton may extend at least 350–400 km north under the Deccan lava cover. This is significant for Precambrian crustal evolution of India besides continental reconstructions.  相似文献   

Sedimentation rates and heavy metals in a macrotidal salt marsh: Bay of Fundy,Canada   总被引：1，自引：0，他引：1  

Ray Kostaschuk  Zhongyuan Chen  Yoshiki Saito  Zhangqiao Wang 《Environmental Geology》2008,55(6):1291-1298

Macrotidal salt marshes play an important role in sedimentary processes in estuaries and can act as a sink for fine sediments and contaminants. This study examines sedimentation rates and the history of heavy metal accumulation in the Allen Creek salt marsh in the Bay of Fundy, Canada. Pb-210 and Cs-137 measurements and accelerated mass spectrometer (AMS) dating indicate a sedimentation rate of about 1.1 cm/year, which is consistent with independent observations. Elevated normalized concentrations of As in the upper section of the deposit may reflect an increase in organic matter content while a consistent decrease in Mn toward the surface of the section may be due to a decrease in natural supply. A peak in metal concentrations in the early to mid twentieth century is attributed to inputs from local foundries.  相似文献   

Evaluation of EO-1 hyperion data for agricultural applications     

Anshu Miglani  S. S. Ray  R. Pandey  J. S. Parihar 《Journal of the Indian Society of Remote Sensing》2008,36(3):255-266

The present study was carried out to evaluate the satellite-based hyperspectral data available from Hyperion onboard EO-1 of NASA for agricultural applications. The study was carried out for Daurala block of Meerut district, using data of March 2005. The preliminary data analysis showed that there are 196 usable bands out of a total of 242 bands. Principal component (PC) analysis showed that about 99% of the information explained in 10 PCs. The atmospherically corrected reflectance, derived from satellite data had good agreement with the ground reflectance, observed using handheld spectroradiometer, with r² ranging from 0.85 to 0.98. A set of twenty most usable bands was selected by the criteria of maximum contribution to first five PCs and the band combinations with least inter-band correlations.  相似文献   

Enclosure experiments on survival and growth of black drum eggs and larvae in lower Chesapeake Bay     

James H. Cowan  Ray S. Birdsong  Edward D. Houde  Jonathan S. Priest  William C. Sharp  George B. Mateja 《Estuaries and Coasts》1992,15(3):392-402

Experiments in 2.2 m³, in situ mesocosm enclosures indicate that black drum, Pogonias cromis, eggs and larvae potentially can survive in the lower Chesapeake Bay at ambient microzooplankton prey levels (≈200 prey 1^?1) in the absence of predators. In growth experiments, larva mean growth rates to 10 d posthatch were similar (0.17 mm d^?1 and 0.18 mm d^?1) when fed at prey levels of 50 prey 1^?1 and 200 prey 1^?1. Individual growth rates, however, were more variable at 50 prey 1^?1. Mortality rates also were comparable in 50 (27% d^?1) and 200 (23% d^?1) prey 1^?1 enclosures. In a second experiment, the predation potentials of the hydromedusa Nemopsis bachei and the lobate ctenophore Mnemiopsis leidyi were estimated in relation to initial black drum egg prey density, presence of alternative <1 mm zooplankton prey, and estimated daily abundance of the jellyfish on the black drum spawning grounds. Mortality rates per medusa and ctenophore were similar (0.02–0.03 d^?1), were not affected by presence of alternative prey, and were directly related to initial egg density. Results suggest that the gelatinous predators, especially the hydromedusa, could have cleared a high (≈38%) but variable fraction of the water column daily of fish eggs and yolk-sac larvae during the black drum spawning season. We hypothesize that the poor or episodic recruitment success of black drum in Chesapeake Bay results from a short spawning season that often coincides with abundance peaks of gelatinous predators and that predation on eggs and yolk-sac larvae may control recruitment.  相似文献   

Radioelemental,petrological and geochemical characterization of the Bundelkhand craton,central India: implication in the Archaean geodynamic evolution     

Labani Ray  P. Nagaraju  S. P. Singh  G. Ravi  Sukanta Roy 《International Journal of Earth Sciences》2016,105(4):1087-1107

  相似文献   

Petrology of parasitic and eccentric cones on the flanks and base of Somma-Vesuvius     

Ray Macdonald  Bogusław Bagiński  Giuseppe Rolandi  Benedetto De Vivo  Anna Kopczyńska 《Mineralogy and Petrology》2016,110(1):65-85

  相似文献