Improved porous silicon microarray based prostate specific antigen immunoassay by optimized surface density of the capture antibody

Enriching the surface density of immobilized capture antibodies enhances the detection signal of antibody sandwich microarrays. In this study, we improved the detection sensitivity of our previously developed P-Si (porous silicon) antibody microarray by optimizing concentrations of the capturing antibody. We investigated immunoassays using a P-Si microarray at three different capture antibody (PSA – prostate specific antigen) concentrations, analyzing the influence of the antibody density on the assay detection sensitivity. The LOD (limit of detection) for PSA was 2.5 ng mL⁻¹, 80 pg mL⁻¹, and 800 fg mL⁻¹ when arraying the PSA antibody, H117 at the concentration 15 μg mL⁻¹, 35 μg mL⁻¹, and 154 μg mL⁻¹, respectively. We further investigated PSA spiked into human female serum in the range of 800 fg mL⁻¹ to 500 ng mL⁻¹. The microarray showed a LOD of 800 fg mL⁻¹ and a dynamic range of 800 fg mL⁻¹ to 80 ng mL⁻¹ in serum spiked samples.     

Relationship between changes in voice pitch and loudness

Changes in mean fundamental frequency accompanying changes in loudness of phonation are analyzed in 9 professional singers, 9 nonsingers, and 10 male and 10 female patients suffering from vocal functional dysfunction. The subjects read discursive texts with noise in earphones, and some also at voluntarily varied vocal loudness. The healthy subjects phonated as softly and as loudly as possible at various fundamental frequencies throughout their pitch ranges, and the resulting mean phonetograms are compared. Mean pitch was found to increase by about half-semitones per decibel sound level. Grossly, the subject groups gave similar results, although the singers changed voice pitch more than the nonsingers. The voice pitch changes may be explained as passive results of changes of subglottal pressure required for the sound level variation.     

Micellar electrokinetic chromatography of ionic compounds: The analysis of hop bitter acids

Successful separation of the six major hop bitter compounds by micellar electrokinetic chromatography depends critically on precise pH control. Any factor which can affect the actual in-column pH must, therefore, also be carefully controlled: it has been found that temperature-induced changes of the buffer pH can cause loss of resolution and even reversals in elution order. The pH level at which the effects occur suggests that the pKa values of the analytes are modified by the micellar medium.     

Crack-growth-rate estimation on a three-point bend specimen during low-cycle fatigue

The ratio of the change of the clip-gage measured crack-opening displacement of a three-point bend specimen to the change of the displacement at the point of application of the cyclic load is shown to vary linearly with the ratio of the crack length to the specimen height. With the aid of this relation, the crack-growth rate is obtained by numerical differentiation of the crack length with respect to the number of load cycles. A clip-gage correction factor is introduced in order to compensate for the use of external edges to position the clip-gage during the experiment.     

The criterion for vacuum stability in Kaluza-Klein supergravity

We prove that in the spectrum of the d = 4 theory obtained by Freund-Rubin compactification of d = 11 superconductivity, only fields of spin 0⁺ can give rise to classical instabilities. The criterion for stability in the 0⁺ sector can be expressed as a certain lower bound on the Lichnerowicz operator Δ_L on the d = 7 compact space. Thus not only are supersymmetric vacua always stable but so are the corresponding non-supersymmetric vacua obtained by reversing the orientation of the compact space, since the 0⁺ spectrum is insensitive to the orientation. Examples are the orientation-reversed spaces with N = 0 obtained from the squashed seven-sphere with N = 1 and from SU(3) ×SU(2) ×U(1) spaces with N = 2 supersymmetry. Product spaces, on the other hand, are always unstable. Finally, we examine the massless sectors of the squashed seven-sphere vacua, and find an additional 135 massless scalars.     

Perturbation and hoarseness: A pilot study of six children's voices

Fundamental frequency (F0) perturbation has been found to be useful as an acoustic correlate of the perception of dysphonia in adult voices. In a previous investigation, we showed that hoarseness in children's voices is a stable concept composed mainly of three predictors: hyperfunction, breathiness, and roughness. In the present investigation, the relation between F0 perturbation and hoarseness as well as its predictors was analyzed in running speech of six children representing different degrees of hoarseness. Two perturbation measures were used: the standard deviation of the distribution of perturbation data and the mean of the absolute value of perturbation. The results revealed no clear relation.     

Chemisorption of CO on Cu(100), Ag(110) and Au(110)

The adsorption of CO on Cu, Ag and Au is studied using core and valence photoemission, X-ray absorption and autoionization of core excited states. The purpose is to investigate the nature of the adsorption bond starting out from the well-established chemisorption system CO/Cu(100)-c(2 × 2), and from the results we suggest that CO forms chemisorbed phases also on Ag(110) and Au(110). The photoemission spectra show strong shake-up satellites both for the valence levels and the core levels. The separation to the satellite appearing closest to the main line is observed to follow the position of the substrate d-band relative to the Fermi level. The CO adsorption strength for the noble metals is deduced to decrease in the order Cu-Au-Ag. This is based on the widths of the XA resonances, which are related to the adsorbate-substrate interaction strength of the core excited states, and the relative shake-up intensities, which are expected to increase with a decreasing adsorption strength in the ground state. The same trends regarding the shake-up intensities are observed both for the valence and core levels.