Search results for "SULFUR"

Psychrotolerant Sulfate-reducing Bacteria from an Oxic Freshwater Sediment Description of Desulfovibrio cuneatus sp. nov. and Desulfovibrio litoralis…

1998

The most abundant culturable sulfate-reducing bacteria were isolated from the littoral sediment of the oligotrophic Lake Stechlin. The strains STL1 and STL4 were obtained from the oxic uppermost layer, while strain STL6 was isolated from the anoxic zone in 20 to 30 mm depth. The isolates showed a striking morphological feature in tapering off at one end of the cell. Physiological characteristics related them to the genus Desulfovibrio. They contained desulfoviridin. H2, formate, pyruvate, lactate, and fumarate were utilized with sulfate, sulfite, thiosulfate, or elemental sulfur as electron acceptors. All isolates were able to reduce oxygen and survived 120 h of aeration. However, aerobic g…

In vitro and in vivo sulfate reduction in the gut contents of the termite Mastotermes darwiniensis and the rose-chafer Pachnoda marginata.

2005

Sulfate-reducing bacteria (SRB) from termites have been assigned to the genus Desulfovibrio. Desulfovibrio intestinalis lives in the gut of the Australian termite Mastotermes darwiniensis. For the first time we were able to enrich and identify a sulfate-reducing bacterium from the gut of the rose-chafer Pachnoda marginata, which showed the highest 16S rDNA sequence identity (93%) to Desulfovibrio intestinalis and Desulfovibrio strain STL1. Compared to Mastotermes darwiniensis (1x10(7) cells of SRB per ml gut contents), sulfate-reducing bacteria occurred in higher numbers in the gut contents of Pachnoda marginata reaching cell titers of up to 2x10(8) cells per ml gut contents. In vitro sulfa…

A spontaneous mitonuclear epistasis converging on Rieske Fe-S protein exacerbates complex III deficiency in mice

2020

We previously observed an unexpected fivefold (35 vs. 200 days) difference in the survival of respiratory chain complex III (CIII) deficient Bcs1lp.S78G mice between two congenic backgrounds. Here, we identify a spontaneous homoplasmic mtDNA variant (m.G14904A, mt-Cybp.D254N), affecting the CIII subunit cytochrome b (MT-CYB), in the background with short survival. We utilize maternal inheritance of mtDNA to confirm this as the causative variant and show that it further decreases the low CIII activity in Bcs1lp.S78G tissues to below survival threshold by 35 days of age. Molecular dynamics simulations predict D254N to restrict the flexibility of MT-CYB ef loop, potentially affecting RISP dyna…

A tandem-flow assembly for the chemiluminometric determination of hydroquinone

2003

A direct chemiluminescent procedure for determination of hydroquinone based on the emergent flow methodology known as multicommutation or tandem-flow is presented for first time. The manifold was based on a set of three channels and three solenoid valves; and, the determination was performed at 60degreesC and at flow-rate of 7.5 ml min(-1). The complete cycle lasted 35 s, which resulted in a sample flow trough of 103 h(-1). The chemical process was the hydroquinone oxidation with the system sulphuric acid-potassium permanganate; and the light emission was clearly enhanced by the presence of quinine sulphate and benzalkonium chloride reaching a detection limit of 30 Rg l(-1). The dynamic int…

A Fully Automated Assembly Using Solenoid Valves for the Photodegradation and Chemiluminometric Determination of the Herbicide Chlorsulfuron

2005

Abstract This paper presents a new photochemiluminescent system for the determination of chlorsulfuron in water samples. The light from a low‐pressure mercury lamp is used as a clean, reproducible, and inexpensive “reagent” for the derivation of the pesticide, performed in glycine buffer at pH 9.5. Then, the photo‐products from irradiation are oxidized by permanganate in sulfuric acid solution. The oxidation reaction was favored by using high temperatures. A comparative study and discussion about the use of polyphosphoric acid instead of sulfuric acid in the oxidation reaction is also presented. The use of solenoid valves allows for the easy, complete automation of the process with low samp…

Flow injection-chemiluminescence determination of octyl dimethyl PABA in sunscreen formulations

2002

Abstract A sensitive flow injection (FI) procedure was developed for the determination of the UV-filter octyl dimethyl PABA in sunscreen formulations based on its chemiluminescence (CL) induced by potassium permanganate in sulfuric acid. Both second-order and log–log calibration graphs can be used to perform the analysis. Ninety injections per hour can be carried out, which means a sample throughput of 18 h −1 if five injections per solution are performed. The limit of detection (3 σ ) was 25 ng ml −1 . The interference effects of the excipient and other UV filters are studied. Sunscreen formulations containing octyl dimethyl PABA were analysed by both the proposed FI-CL method and a liquid…

Determination of inorganic species of Sb and Te in cereals by hydride generation atomic fluorescence spectrometry

2011

A non-chromatographic fast, sensitive and easy method has been developed for the determination of Sb(III), Sb(V), Te(IV) and Te(VI) in cereal samples. The procedure is based on ultrasound assisted extraction and determination by hydride generation atomic fluorescence spectrometry (HG AFS). Preliminary studies were made in order to get the best extraction efficiency using 1 mol L-1 phosphoric acid, 1 mol L-1 nitric acid, aqua regia, 1 mol L-1 sulfuric acid and 6 mol L-1 hydrochloric acid. The extraction with aquaregia showed a clear interconversion of the species during the process, being H2SO4 the best extractant with efficiencies greater than 90% from the total content of Sb and Te quantif…

Active alkaline traps to determine acidic-gas ratios in volcanic plumes: Sampling techniques and analytical methods

2014

In situ measurements have been the basis for monitoring volcanic gas emissions for many years and—being complemented by remote sensing techniques—still play an important role to date. Con- cerning in situ techniques for sampling a dilute plume, an increase in accuracy and a reduction of detection limits are still necessary for most gases (e.g., CO2, SO2, HCl, HF, HBr, HI). In this work, the Raschig-Tube tech- nique (RT) is modified and utilized for application on volcanic plumes. The theoretical and experimental absorption properties of the RT and the Drechsel bottle (DB) setups are characterized and both are applied simultaneously to the well-established Filter packs technique (FP) in the …

Simultaneous clean up of fish fat containing low levels of residues and separation of PCB from chlorinated pesticides by thin-layer chromatography

1974

The Significance of Ionic Bonding in Sulfur Dioxide: Bond Orders from X-ray Diffraction Data

2012

A novel refinement technique for X‐ray diffraction data has been employed to derive S-O bond orders in sulfur dioxide experimentally. The results show that ionic S-O bonding dominates over hypervalency.