488 research outputs found
A study of certain trace metals in sea water using anodic stripping voltammetry
Submitted in partial fulfillment of the
requirements for the degree of
Doctor of Philosophy at the
Massachusetts Institute of Technology
and the Woods Hole Oceanographic Institution
January, 1970Anodic stripping voltammetry utilizing a thin film mercury composite graphite electrode has been evaluated and applied for the direct analysis of the metals, Zn, Cu, Pb, and Cd in sea water. The electrode was observed to follow theoretical behavior for thin film electrodes and the technique was found not to be adversely affected by dissolved organic material in sea water. Good precision (ca., 5%) was obtained in both coastal and open ocean waters at the in situ concentrations of Zn, Cu, Pb, and Cd. It was shown that this method is at present most suitable for
measurements of Cu, Pb, and Cd in sea water. Evidence is given suggesting that
Ni may interfere with the determination of Zn through formation of an intermetallic
compound, and further studies are indicated to understand this phenomenon. The
anodic stripping apparatus was adapted and used conveniently on shipboard. It was
demonstrated that stripping analysis could be combined with a method for the destruction
of dissolved organic matter (photo-oxidation with ultra-violet radiation), and with an addification procedure to obtain measurements of trace metal speciation in sea water. An argument for the existence of Cu-aspartic acid chelates in sea water has been described theoretically and demonstrated empirically; suggesting that a significant fraction of Cu and other trace metals may be expected to be organically sequestered in sea water. A study of coastal waters employing the total method
(anodic stripping-photo-oxidation-acidification) indicated the presence of a significant
group of organic ligands that complex Cu (ca., 60%). It was also shown
that the waters subject to gross pollution contain about 30% of the total Cu in very
stable organic complexes that release Cu only when the dissolved organic matter is
destroyed, and not when the pH of this sea water is adjusted to 3.
An open ocean trace metal study of a thermal-front zone in the western
Sargasso Sea gave data for Cu, Zn, Pb, and Cd that compared favorably with other relevant investigations. Higher free metal concentrations were observed south of the front than to the north, providing further evidence that these fronts may mark a
change between southern and northern conditions in the Sargasso Sea. Data obtained
from shipboard analyses using the total analytical method indicates the presence of
weak organic complexes with Cu and Pb in open ocean waters.This research has been supported for various periods by funds granted by the
U.S. Office of Naval Research Contract 1841 (74), U.S. Atomic Energy
Commission Contracts AT (30-1)-1919, and AT (30-1)-905, and a Graduate
Fellowship provided by the Woods Hole Oceanographic Institution
Bioaccumulation and trophic transfer of methylmercury in Long Island Sound
Author Posting. © Springer, 2006. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Archives of Environmental Contamination and Toxicology 51 (2006): 416-424, doi:10.1007/s00244-005-0265-7.Humans are exposed to methylmercury (MeHg) principally by consumption of marine fish. The coastal zone supports the majority of marine fish production, and may therefore be an important source of MeHg to humans; however, little is known about the bioaccumulation or MeHg in near-shore marine ecosystems. We examined MeHg in microseston, zooplankton, a decapod crustacean and four representative species of finfish that differ in trophic status and/or prey selection in Long Island Sound (LIS), a large coastal embayment in the northeastern United States. MeHg biomagnifies in LIS; levels in microseston were 104.2 greater than those in water and 2.3-fold less than zooplankton. MeHg concentrations were related positively to fish length for each species, but often varied considerably among larger individuals. This may be due to differences in the past dietary MeHg exposure of these fish, some of which are migratory. Sedimentary production and mobilization can account for most of the MeHg in microseston of LIS, and by extension, other near-shore locations. Hence, much of the MeHg in higher trophic levels of coastal marine ecosystems, including fishes destined for human consumption, may be attributed to net sedimentary production and dietary bioaccumulation.This study was supported by a STAR grant (R827635) and graduate student fellowship (U91591801) from the U.S. EPA, and the Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution, with funding provided by the Doherty Foundation
Molecular Characterisation of Bacteriophage K Towards Applications for the Biocontrol of Pathogenic Staphylococci
End of project reportThe aim of this work was to characterise staphylococcal bacteriophage (a bacterial virus) and to assess their potential as therapeutic agents against pathogenic strains of Staphylococcus aureus, particularly mastitis-causing strains. The project included the use of two newly isolated phage CS1 and DW2, and an existing polyvalent phage. The new phage were isolated from the farmyard and characterised by electron microscopy and restriction analysis. Both phage were shown to belong to the Siphoviridae family and were lytic for representatives of all three clonal groups of Irish mastitis-associated staphylococci. A cocktail of three phage (CS1, DW2 and K) at 108 (plaque forming units) PFU/ml was infused into cows teats in animal trials. The lack of an increase in somatic cell counts in milks indicated strongly that the phage did not irritate the animal. In addition, the most potent phage used in this study, phage K, was further studied by genome sequencing, which revealed a linear DNA genome of 127,395 base pairs, which encodes 118 putative ORFs (open reading frames)
The instructional use of computers in dental education
The formation, development, and current status of a major instructional materials preparation project, the CAIDENT Project, at the School of Dentistry, The University of Michigan, is discussed. A rationale for the place of individualized instruction in general and CAI in particular is presented. Topics include staffing strategies and ways to encourage faculty participation. Examples are included to illustrate operational CAI programs at Michigan in Pedodontics and Oral Diagnosis. Comments about the future of CAI in the Health Sciences are included.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33806/1/0000062.pd
Correction to “Mercury and monomethylmercury in fluids from Sea Cliff submarine hydrothermal field, Gorda Ridge”
Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 34 (2007): L02603, doi:10.1029/2006GL028747
Nurses\u27 Alumnae Association Bulletin - Volume 18 Number 1
Alumnae Notes
Central Dressing Room
Committee Reports
Digest of Alumnae Association Meetings
Graduation Awards - 1952
Greetings from Miss Childs
Greetings from the President
Marriages
Modern Trends in Orthopaedic Surgery
Necrology
New Arrivals
Physical Advances at Jefferson Hospital - 1953
Staff Activities - 1952-1953
Student Activities
The Artificial Heart Lung Machin
Trial-by-Trial Adjustments of Cognitive Control Following Errors and Response Conflict are Altered in Pediatric Obsessive Compulsive Disorder
Background: Impairments of cognitive control have been theorized to drive the repetitive thoughts and behaviors of obsessive compulsive disorder (OCD) from early in the course of illness. However, it remains unclear whether altered trial-by-trial adjustments of cognitive control characterize young patients. To test this hypothesis, we determined whether trial-by-trial adjustments of cognitive control are altered in children with OCD, relative to healthy controls. Methods: Forty-eight patients with pediatric OCD and 48 healthy youth performed the Multi-Source Interference Task. Two types of trial-by-trial adjustments of cognitive control were examined: post-error slowing (i.e., slower responses after errors than after correct trials) and post-conflict adaptation (i.e., faster responses in high-conflict incongruent trials that are preceded by other high-conflict incongruent trials, relative to low-conflict congruent trials). Results: While healthy youth exhibited both post-error slowing and post-conflict adaptation, patients with pediatric OCD failed to exhibit either of these effects. Further analyses revealed that patients with low symptom severity showed a reversal of the post-conflict adaptation effect, whereas patients with high symptom severity did not show any post-conflict adaptation. Conclusion: Two types of trial-by-trial adjustments of cognitive control are altered in pediatric OCD. These abnormalities may serve as early markers of the illness
Nurses\u27 Alumnae Association Bulletin - Volume 7 Number 11
Anna M. Shafer
Barton Memorial Division
Births
Changes in the Ophthalmology Division
Change of Address
Clara Melville Fund
Continental Tour
Deceased
Digest of Meetings
Inter-County Hospitalization Plan
Katherine Childs\u27 Letter
Lost Members
Marriages
Miscellaneous
Nursing Home Committee\u27s Report
Physical Advantages
President James L. Kauffman\u27s Letter
President\u27s Greeting
Private Duty Section
Prizes
Relief Fund
School Nursing
Silhouette of a Public Health Nurse
Rooming-in of Infant with Mother
Staff Activities
The Student
White Haven Divisio
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