The activity of calcium in plaque fluid is needed to calculate the saturation level of that fluid relative to the tooth mineral. One method to determine the calcium activity in very small plaque fluid samples is by micro ion-selective electrode (ISE). Two commercially available calcium ionophores, a neutral-carrier and a charged-carrier, were evaluated in micro ISEs and compared to a commercial...

fe2+ ion-selective membrane sensor has been fabricated from polyvinyl chloride (pvc) matrixmembrane containing neutral carrier tetra phenyl porphyrin (tpp) ionophore. the addition ofsodium tetraphenylborate (natpb) and the plasticizer dbp has been found to substantiallyimprove the performance of the sensor. the best performance was obtained with the sensor havinga membrane of composition of tpp...

Fe2+ ion-selective membrane sensor has been fabricated from polyvinyl chloride (PVC) matrixmembrane containing neutral carrier tetra phenyl porphyrin (TPP) ionophore. The addition ofsodium tetraphenylborate (NaTPB) and the plasticizer DBP has been found to substantiallyimprove the performance of the sensor. The best performance was obtained with the sensor havinga membrane of composition of TPP...

A quantitative study of the carrier localization in GaN under large hydrostatic pressure is presented using infrared reflection and Raman spectroscopy. The free-carrier concentration in as-grown n-type GaN crystals is determined optically from the phonon-plasmon–coupled mode and an analysis of the dielectric function. A strong decrease from 1310 cm at ambient pressure to only 3310 cm at a press...

Single grain boundaries in CuGaSe2 have been grown epitaxially. Hall measurements indicate a barrier of 30-40 meV to majority carrier transport. Nevertheless, local surface potential measurements show the absence of space charge around the grain boundary; i.e., it is neutral. Theoretical calculations [Persson and Zunger, Phys. Rev. Lett. 91, 266401 (2003)] have predicted a neutral barrier for t...

Saccharopolyspora erythraea acyl-carrier protein, highly expressed from a T7-based expression plasmid in Escherichia coli, can be selectively released from the cells in near-quantitative yield by a single cycle of freezing and thawing in a neutral buffer. Electrospray mass spectrometry was used to confirm that the recombinant S. erythraea acyl-carrier protein over-expressed in E. coli is presen...