Search

With the combination of the gold nanoparticle (AuNP)-based visual test with hollow fiber supported liquid membrane (HFSLM) extraction, a highly sensitive and selective method was developed for field detection of mercuric ion ([Hg.sup.2+]) in environmental waters. [Hg.sup.2+] in water samples was extracted through HFSLM and trapped in the aqueous acceptor and then visually detected based on the red-to-blue color change of 3-mercaptopropionic acid-functionalized AuNP (MPA-AuNP) probe. The highest extraction efficiency of [Hg.sup.2+] was obtained by using a 600 mL sample (pH 8.0, 2.0% (w/v) NaCl), ~35 [micro]L of acceptor (10 mM of 2,6-pyridinedicarboxylic acid, pH 4.0) filled in the lumen of a polypropylene hollow fiber tubing (55 cm in length, 50 [micro]m wall thickness, 280 [micro]m inner diameter), a liquid membrane of 2.0% (w/v) trioctycphosphine oxide in undecane, and a shaking rate of 250 rpm. The chromegenic reaction was conducted by incubating the mixture of MPA-AuNP stock solution (12 [micro]L, 15 nM), Tris-borate buffer solution (18 [micro]L, 0.2 M, pH 9.5), and acceptor (30 [micro]L) at 30[degrees]C for 1 h. The detection limit can be adjusted to 0.8 [micro]g/L [Hg.sup.2+] (corresponding to an enrichment factor of ~1000 in the HFSLM) and 2.0 [micro]g/L [Hg.sup.2+] (the U.S. Environmental Protection Agency limit of [[Hg.sup.2+]] for drinkable water) by using extraction times of 3 and 1 h, respectively. The proposed method is extremely specific for [Hg.sup.2+] with tolerance to at least 1000-fold of other environmentally relevant heavy and transition metal ions and was successfully applied to detect [Hg.sup.2+] in a certified reference water sample, as well as real river, lake, and tap water samples. 10.1021/ac100541s

Most soils in the Central Florida Ridge (CFR) area are Entisols that contain >95% sand, Abbreviations: CFR, Central Florida Ridge.

We have constructed and characterized a simple probe that is suitable for accurate measurements of irradiance in the UV to the vacuum UV spectral range. The irradiance meter consists of a PtSi detector located behind a 5-mm-diameter aperture. The probe was characterized at various wavelengths ranging from 130 to 320 nm by use of continuously tunable synchrotron radiation from the Synchrotron Ultraviolet Radiation Facility III. We determined the irradiance responsivity by scanning a small monochromatic beam over the active area of the irradiance meter and measuring its response on a grid with regular spacing. The angular response was also determined and shown to be suitable for applications such as photolithography. In addition, we studied the radiation damage using a 157-nm excimer laser and found that the irradiance meter can endure more than 100 J/[cm.sup.2] of 157-nm radiation before a noticeable change occurs in its responsivity. Many industrial applications such as UV curing, photolithography, or semiconductor chip fabrication that require accurate measurement of the irradiance would benefit from having such a stable, accurate UV irradiance meter. OCIS codes: 120.5630, 120.0280, 040.6070, 040.7190.

Tests are conducted to determine the comparative performance and accuracy of Sippican Inc.'s eXpendable Conductivity Temperature Depth (XCTD) probes as opposed to CTD sondes. As previously seen in the THETIS-I experiment, errors that occurred due to experimental conditions are segregated from errors caused by the equipment. Results show the relative accuracy of XCTD sensors based on the manufacturer's specifications.