Photobiogeochemical reactions involving metal species can be a source of naturally occurring nanoscale materials in the aquatic environment. This study demonstrates that, under simulated sunlight exposure, ionic Ag is photoreduced in river water or synthetic natural water samples that contain natural organic matter (NOM), forming Ag nanoparticles (AgNPs) that transform in size and shape and precipitate out upon extended irradiation. We show that the dissolved oxygen concentration does not appear to affect AgNP formation rates, indicating that reactive transients such as superoxide, hydrated electron, and triplet NOM do not play a large role. By varying pH and NOM concentrations and adding competing cations on the AgNP formation, we present three lines of evidence to show that Ag ion photoreduction likely involves ionic Ag binding to NOM. Our work suggests that photochemical reactions involving ionic Ag and NOM can be a source of nanosized Ag in the environment.

RDS remains a significant morbidity in full-term NICU admission. When compared with controls, admissions to our NICU with any respiratory morbidity were more likely to be delivered by cesarean to a mother with hypertension or diabetes during pregnancy.

rapidly advancing spinal cord compression.4 A normal cell count in the C.S.F., an increase in protein, and a more or less complete block on myelography are to be expected.5 According to Arseni and Samitca4 it is difficult, if not impossible, to differentiate between extramedullary and intramedullary tuberculoma before surgery as the radiological picture in both is identical. To the best of our knowledge this is the first case described showing the true intramedullary nature of a tuberculoma before surgery. It draws attention to the unusual presentations of tuberculosis in the immigrant population and adds another cause to the radiological list of intramedullary spinal lesion.

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