A durable and inexpensive pump profiler to monitor stratified water columns with high vertical resolution.

A pump profiling system for real time sample collection has been constructed for a cost of <$1000 (USD) and mated with a ship's rosette that has conductivity, temperature, depth (CTD) and other sensors. The system permits the collection of ~15 L of water in one minute without exposure to O from air for discrete sampling of chemical, microbial and other constituents as well as for real time analyses using sensors. We also coupled a shipboard voltammetry system with solid-state microelectrodes to detect dissolved O and HS.

A 1,2,3-dithiazolyl-o-naphthoquinone: a neutral radical with isolable cation and anion oxidation states.

Under aprotic conditions, the reaction of 4-amino-1,2-naphthoquinone with excess S2Cl2 generates 4,5-dioxo-naphtho[1,2-d][1,2,3]dithiazol-2-ium chloride in a typical Herz condensation. By contrast, prior literature reports an imine (NH) product, 4,5-dioxo-1H-naphtho[1,2-d][1,2,3]dithiazole, for the same reaction performed in acetic acid. Herein, the cation product is isolated with four different counter-anions (Cl(-), GaCl4(-), FeCl4(-) and OTf(-)).

Using in situ voltammetry as a tool to identify and characterize habitats of iron-oxidizing bacteria: from fresh water wetlands to hydrothermal vent sites.

Iron-oxidizing bacteria (FeOB) likely play a large role in the biogeochemistry of iron, making the detection and understanding of the biogeochemical processes FeOB are involved in of critical importance. By deploying our in situ voltammetry system, we are able to measure a variety of redox species, specifically Fe(ii) and O2, simultaneously. This technique provides significant advantages in both characterizing the environments in which microaerophilic FeOB are found, and finding diverse conditions in which FeOB could potentially thrive.

Phototrophic sulfide oxidation: environmental insights and a method for kinetic analysis.

Previously, we presented data that indicated microbial sulfide oxidation would out-compete strictly chemical, abiotic sulfide oxidation reactions under nearly all conditions relevant to extant ecosystems (Luther et al., 2011). In particular, we showed how anaerobic microbial sulfide oxidation rates were several orders of magnitude higher than even metal catalyzed aerobic sulfide oxidation processes.

Metal complexes of bridging neutral radical ligands: pymDTDA and pymDSDA.

Metal complexes of the 4-(2'-pyrimidyl)-1,2,3,5-dithiadiazolyl (pymDTDA) neutral radical ligand and its selenium analogue (pymDSDA) are presented. The following series of metal ions has been studied using M(hfac)(2) as the coordination fragment of choice (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato): Mn(II), Co(II), Ni(II), and Zn(II). The binuclear cobalt and nickel complexes of pymDTDA both exhibit ferromagnetic (FM) coupling between the unpaired electrons on the ligand and the metal ion, while the binuclear zinc complex of pymDTDA is presented as a comparative example incorporating a diamagnetic metal ion.

Thermodynamics and kinetics of sulfide oxidation by oxygen: a look at inorganically controlled reactions and biologically mediated processes in the environment.

The thermodynamics for the first electron transfer step for sulfide and oxygen indicates that the reaction is unfavorable as unstable superoxide and bisulfide radical ions would need to be produced. However, a two-electron transfer is favorable as stable S(0) and peroxide would be formed, but the partially filled orbitals in oxygen that accept electrons prevent rapid kinetics. Abiotic sulfide oxidation kinetics improve when reduced iron and/or manganese are oxidized by oxygen to form oxidized metals which in turn oxidize sulfide.

A new polymorph of dichloridotriphenylantimony.

In a new polymorphic form of dichloridotriphenylantimony, [Sb(C(6)H(5))(3)Cl(2)], there are two crystallographically unique molecules in the asymmetric unit and it has been determined that this polymorph is one of two kinetically favoured phases of pure dichloridotriphenylantimony, both of which have Z' > 1. A third polymorph, corresponding to (C(6)H(5))(3)SbCl(1.8)F(0.

Fiber-optic scanning two-photon fluorescence endoscope.

We report on the development of a miniature, flexible, fiber-optic scanning endoscope for two-photon fluorescence imaging. The endoscope uses a tubular piezoelectric actuator for achieving two-dimensional beam scanning and a double-clad fiber for delivery of the excitation light and collection of two-photon fluorescence. Real-time imaging of fluorescent beads and cancer cells has been performed.

Real-time in vivo blood-flow imaging by moving-scatterer-sensitive spectral-domain optical Doppler tomography.

We present a moving-scatterer-sensitive optical Doppler tomography (MSS-ODT) technique for in vivo blood flow imaging in real time by using a spectral-domain optical coherence tomography system. In MSS-ODT the influence of stationary scatterers is suppressed by subtracting adjacent complex axial scans before calculating the Doppler frequency shift. We demonstrate that MSS-ODT is a useful technique for accurate determination of blood vessel size by imaging flow in a small capillary tube with a 75 microm inner diameter.