Spectroscopy in separated flames-III Use of the separated nitrous oxide-acetylene flame in thermal emission spectroscopy

The separation of a premixed nitrous oxide-acetylene flame at a modified commercial burner is described. The reducing interconal zone of the fuel-rich separated flame exhibits low radiative background. The reducing atmosphere and high temperature of this flame result in an effective medium for the excitation of the atomic line spectra of the refractory elements. The use of the fuel-rich flame in the flame photometry of these elements has been investigated.     

Temperature profiles in nitrous oxide supported acetylene flames at atmospheric pressure

Temperature profiles have been established at three mixture strengths of the nitrous oxide-acetylene flame used in atomicabsorption spectroscopy. Measurement of the electronic excitation temperature of the red-feather zone by the sodium line-reversal and iron two-line methods yields average maximum temperatures of 3070 and 3025 +/- 50 degrees K respectively. This is significantly lower than the only previously reported value, 3228 degrees K. Other temperature measurements obtained by studying intensity distribution of NH rotational fine structure and CN vibrational structure yielded less precise results, but suggest a state of thermal equilibrium in the flame. The temperature gradient within the flame shows a steady decrease with height above the primary zone. A study of CN spectra and the zones of persistence of free atoms and of metal oxide species suggests a mechanism of free atom production within the cyanogen zone whereby the removal of oxidizing radicals by CN promotes dissociation of metal oxide species previously formed in the primary zone of the flame.     

Carminic acid as a reagent for the spectrofluorimetric determination of molybdenum and tungsten-I Development of procedures

Carminic acid forms red fluorescent complexes with molybdenum(VI) and tungsten(VI) which provide spectrofluorimetric methods for the determination of these metals in the range 0.1–0.9 ppm and 0.4–0.36 ppm at pH 5.2 and 4.6 respectively. The optimum conditions for the analytical procedures have been established, and the effects of a wide range of cations and anions have been investigated. The reagent forms 1:1 complexes with both molybdenum and tungsten, and the conditional stability constants have been evaluated.     

Expression of ionotropic glutamate receptors in the retina of the rdta transgenic mouse

Background

One mechanism that directs the action of the second messengers, cAMP and diacylglycerol, is the compartmentalization of protein kinase A (PKA) and protein kinase C (PKC). A-kinase anchoring proteins (AKAPs) can recruit both enzymes to specific subcellular locations via interactions with the various isoforms of each family of kinases. We found previously that a new class of AKAPs, dual-specific AKAPs, denoted D-AKAP1 and D-AKAP2, bind to RIα in addition to the RII subunits.

Results

Immunohistochemistry and confocal microscopy were used here to determine that D-AKAP1 colocalizes with RIα at the postsynaptic membrane of the vertebrate neuromuscular junction (NMJ) and the adjacent muscle, but not in the presynaptic region. The labeling pattern for RIα and D-AKAP1 overlapped with mitochondrial staining in the muscle fibers, consistent with our previous work showing D-AKAP1 association with mitochondria in cultured cells. The immunoreactivity of D-AKAP2 was distinct from that of D-AKAP1. We also report here that even though the PKA type II subunits (RIIα and RIIβ) are localized at the NMJ, their patterns are distinctive and differ from the other R and D-AKAP patterns examined. PKCβ appeared to colocalize with the AKAP, gravin, at the postsynaptic membrane.

Conclusions

The kinases and AKAPs investigated have distinct patterns of colocalization, which suggest a complex arrangement of signaling micro-environments. Because the labeling patterns for RIα and D-AKAP 1 are similar in the muscle fibers and at the postsynaptic membrane, it may be that this AKAP anchors RIα in these regions. Likewise, gravin may be an anchor of PKCβ at the NMJ.     

Indirect Amplification Determination of Thorium by Atomic Absorption Spectroscopy

Thorium may not be determined by direct atomic absorption spectroscopy in flame media with appreciable sensitivity because of inefficient atomisation. Earlier papers from this laboratory have described indirect amplification procedures for similarly difficult elements e.g. niobium¹ and titanium² by atomic absorption spectroscopy· Madison and Guyon³ have developed a solution spectrophotometric procedure for thorium in which the heteropoly acid complex of thorium with phosphomolybdic acid is formed and reduced to the ‘heteropoly blue’. Strict adherence to time of addition of reagents is required in this procedure, and. it is necessary to effect an initial separation of the thorium from most other cations present in the sample.     

Application of indirect methods in analysis by atomic-absorption spectrometry

The use of indirect methods for the determination by atomic-absorption spectrometry of those elements not normally amenable to sensitive determination by this technique is reviewed. The available indirect methods are classified into five general types of procedure; specific reported procedures for the determination of metals, non-metals and some compounds are discussed.     

A simple low-power reduced-pressure microwave plasma source for emission spectroscopy

The construction of a simple low-power microwave plasma source for emission spectroscopy is described.