Influence of HbCO structure of the bar-headed goose on photolysis thermodynamics as studied by the nanosecond laser-ultrasonic technique.

The bar-headed goose, a specialized high-altitude species, has a capacity for high oxygen uptake from a hypoxic environment. It thus has a higher oxygen affinity than other bird species of lower-altitude environments. Oxygen affinity is determined by molecular structures and genetic mutations of hemoglobin (Hb), which can also influence the coordinating structures and dynamics of oxygen-Hb. To explore the structural differences in Hbs as between high and low altitude species, photolysis dynamic parameters, including quantum yield, enthalpy, and conformational volume changes in carboxy-Hbs (HbCO) for the bar-headed goose and low altitude counterparts (the Chinese goose and chicken) were investigated by the laser pumping-probing technique and photoacoustic calorimetry. Comparing the photolysis results for HbCO of the three species, the enthalpy and conformational volume changes of the bar-headed goose were much smaller than those of the others, although the quantum yields of all three species are similar. To explain the possible mechanisms of these differences, modifications of salt bridges and key residue mutations at the α ß subunit interfaces of the proteins are described and discussed briefly.

Characteristics of surface acoustic waves excited by (1120) ZnO films deposited on R-sapphire substrates.

(1120)-textured ZnO films are deposited on Rsapphire substrate by RF magnetron sputtering and the effects of deposition conditions on ZnO films are investigated. The chemical compositions of the ZnO films are characterized by X-ray photoelectron spectroscopy and the results indicate that the ratio of latticed oxygen to zinc increases with increasing of oxygen concentration in the sputtering gas, which demonstrates the improvement of crystal structures in ZnO films. To investigate the characteristics of surface acoustic waves excited by the (1120)-textured ZnO films, SAW delay lines based on layered structures of (1120) ZnO film/R-sapphire substrate are fabricated, in which Rayleigh and Love modes are excited along the (0001)- and (1100)-directions of the ZnO films, respectively. The phase velocities and electromechanical coupling factors of both wave modes are characterized as functions of the film-thickness-to-wavelength ratio. The acoustic properties of the layered structures are calculated using the transfer matrix method. The experimental and theoretical results are in good agreement with each other.

Experimental study of Love-wave immunosensors based on ZnO/LiTaO3 structures.

Experimental study of Love-mode immunosensors based on structures of ZnO/36 degrees YX-LiTaO3 is presented, in which the ZnO films with c-axis (002) orientation have been successfully grown on the 36 degrees YX-LiTaO3 substrates by RF magnetron sputtering technique. Then the Love-mode immunosensors based on the ZnO/36 degrees YX-LiTaO3 structures and monitoring antibody-antigen immunoreactions in aqueous solutions in real time are fabricated. The experimental results show that the optimal thickness of ZnO layers is about 1.20 microm in the structures deposited on 36 degrees YX-LiTaO3 substrates, which is much less than that of SiO2 overlayers about 6 microm. The antibody-antigen immunoreaction experiments also show that the frequency shifts of the sensors with 1.33 microm ZnO films are proportional to the concentration of antigen in solution as the concentration range less than 100 microg/ml.

Enthalpy and conformational volume changes of mammalian oxy-hemoglobins investigated by pulsed photoacoustic calorimetry.

Enthalpy and conformational volume changes induced by laser photo-dissociation reactions of mammalian oxy-hemoglobin, such as human, bovine, pig, horse and rabbit oxy-hemoglobins, are investigated by pulsed photoacoustic calorimetry. Generally, the response time of the photoacoustic calorimetry is restricted by the width of the laser pulse and the bandwidth of the acoustic detector. Considering the time window of the experimental system, the enthalpy and conformational volume changes detected should be caused by the tertiary relaxation of the heme proteins. In order to calculate the enthalpy and conformational volume changes, the quantum yields of the photo-dissociation products of oxy-hemoglobins must be measured and taken into account. Finally, the enthalpy and conformational volume changes of the oxy-hemoglobins connected with the tertiary relaxation are obtained, which show that for all measured mammalian oxy-hemoglobins the values of enthalpy changes are in the range of 30.0-46.8 kcal/mol and volume changes are of 2.3-7.8 ml/mol although the quantum yields for the different species may have much bigger differences. A possible explanation of the results is presented.