Distribution, abundance and biomass of Ampelisca sp. in the Iranian continental shelf of the Oman Sea

This study was conducted to determine distribution, abundance and biomass of Ampelisca sp. in the Iranian continental shelf of the Oman Sea from Jask to Gwadar (approximately 350 km stretch). Sampling was carried out in 10, 50,100 and 200m depth along five transects of approximately equal distances from each other. Sampling was done with Van Veen grab (0.1 m^2) in three replicates; temperature, salinity, and Dissolve oxygen were recorded by CTD, sediment sample was collected for analysis of physical parameters for sediment at each station. The PCA and correlation of Ampelisca sp. abundance and biomass with all the environmental parameters were determined. The maximum abundance and biomass of Ampelisca sp. was recorded at 10m depth, which decreased as depth increased. It was observed significant correlation among abundance and biomass with dissolved oxygen, sand percentage and temperature

ELISA on a microchip with a photodiode for detection of amphetamine in plasma and urine

A rapid and sensitive assay was developed for the detection of amphetamine in plasma and urine. The method relies on the principle of competitive ELISA (enzyme-linked immunosorbent assay). A flow microchip with a total volume of 7 µL was used for the development of a chemiluminescent ELISA technique. Solutions, samples, and the chemiluminescence substrate were injected by a flow system, and a photodiode detector was used to measure the light intensity. The incubation time of the competitor (competition phase) was reduced to 10 min. Calibration curves corresponding to analyte concentrations ranging from 40 to 1000 µg/L in urine samples and from 6 to 96 µg/L in plasma samples were obtained. The detection limits were in the region of 20 and 6 µg/L in urine and plasma, respectively. The main focus of the work was on speed, reliability, reproducibility, and operational stability of the assay. This method was proven readily adaptable to automation and provided reproducible results

Dc-resistometric Urea Sensitive Device Utilizing A Conducting Polymer Film For the Gas-phase Detection of Ammonia

The construction of an urea sensitive device based on a conducting polymer is described. The conducting polymer (polypyrrole) was exposed only to a gas-phase; this led to a significant improvement in its stability. A DC-resistometric measuring principle was used, which required only simple measuring equipment. The device responded rapidly to between 0 and 500 mM urea, with resistance changes of between 0 and 400 Ohms. The measurement of the urea content of a sample and subsequent regeneration took 20 min

Development of an amperometric biosensor based on acetylcholine esterase covalently bound to a new support material.

A new type of amperometric biosensor based on immobilised acetylcholine esterase was designed and constructed. The enzyme was immobilised on a flow-through working electrode, which was prepared from reticulated vitreous carbon (RVC) or from a composite material consisting of RVC and superporous agarose. The sensor was operated in FIA mode using acetylthiocholine as a substrate. The sensor responded to inhibitors such as paraoxon-10(-9) mol was detected by the sensor in a non-optimised configuration. The practical lifetime of the sensor was at least 1 month

Coulometric determination of NAD(+) and NADH in normal and cancer cells using LDH, RVC and a polymer mediator

An electrochemical method for the measurement of NAD(+) and NADH in normal and cancer tissues using flow injection analysis (FIA) is reported. Reticulated vitreous carbon (RVC) electrodes with entrapped L-lactate dehydrogenase (LDH) and a new redox polymer containing covalently bound toluidine blue O (TBO) were employed for this purpose. Both NAD(+) and NADH were estimated coulometrically based on their reaction with LDH. The latter was immobilized on controlled pore glass (CPG) by cross-linking with glutaraldehyde and packed within the RVC. The concentrations of NAD(+) and NADH in the tissues, estimated using different electron mediators such as ferricyanide (FCN), meldola blue (MB) and TBO have also been compared. The effects of flow rate, pH, applied potential (versus Ag/AgCl reference) and adsorption of the mediators have also been investigated. Based bn the measurements of NAD(+) and NADH in normal and cancer tissues it has been concluded that the NADH concentration is lower, while the NAD(+) concentration is higher in cancer tissues. Amongst the electron mediators TBO was found to be a more stable mediator for such measurements. (C) 1999 Elsevier Science B.V. All rights reserved

Low-pressure thermogravimetric analysis for finding sublimation temperatures for organic precursors in atomic/molecular layer deposition

Atomic/molecular layer deposition (ALD/MLD) is strongly emerging as the state-of-the-art gas-phase fabrication technique for novel functional inorganic-organic thin-film materials. In the actual ALD/MLD process development, selecting the proper sublimation temperatures for the inorganic and organic precursors is an important task. In particular, the latter ones tend to require higher sublimation temperatures. In this work, we systematically investigate a representative set of most common ALD/MLD organic precursors using low-pressure (4 mbar) thermogravimetric (TG) analysis. The onset temperature (TG(onset)) where the weight loss starts is found to well foretell us the optimal precursor source temperature (T-MLD) for ALD/MLD; typically, the T(MLD)value used in a practical ALD/MLD experiment is lower by approximately 14% than the TG(onset)value. Moreover, we discuss the possibility to utilize the melting point of the compound as a starting point if such vacuum TG measurements are not available.Peer reviewe