Norberto Cella

Photosynthetic O2 evolution in maize inbreds and their hybrids can be differentiated by open photoacoustic cell technique

Abstract Photosynthetic efficiency is considered one of the traits potentially suitable to differentiate hybrids from their inbred lines. Previous evaluations concerning photosynthetic efficiencies of maize (Zea mays L.) plants in the field have shown inconsistent and contradictory data. In this work, we attempted to study photosynthetic O2 evolution through photoacoustic spectroscopy in intact undetached leaves of dark-adapted seedlings of inbreds and their hybrids. The results indicate that photosynthetic efficiencies of inbreds and hybrids can be differentiated by photoacoustic measurements of oxygen evolution, providing a parameter that might prove useful in evaluating plant genotypes.

OPC technique for in vivo studies in plant photosynthesis research

The open photoacoustic cell (OPC) technique is applied to photosynthesis research in leaves, where the leaf is still attached to the plant. It is shown that real in situ and in vivo measurements of photosynthetic activities in leaves can be performed. The dehydration effect after cutting the leaf from the plant was monitored and some qualitative measurements related to photosynthetic activities are reported in order to show the usefulness of this technique in this field.

In vivo and in situ measurements of spectroscopic and photosynthesis properties of undetached maize leaves using the open photoacoustic cell technique

Abstract A new and highly sensitive method, based on the photoacoustic effect, is described for in vivo and in situ studies of photosynthetic activity of undetached leaves. The general utility of this simple photothermal method is demonstrated by examining the spectroscopy and photosynthetic activity of green, striped, and albino plants of maize (Zea mays L.).

On the use of the open photoacoustic cell technique for studying photosynthetic O2 evolution of undetached leaves: Comparison with Clark‐type O2 electrode

The leaf photosynthetic O2 evolution detected by the open photoacoustic cell (OPC) technique is compared to the measurements using a Clark‐type O2 electrode detector. In vivo and in situ measurements were carried out with undetached maize leaves. From the correlation between these two methods the possibility of a calibration is proposed for the oxygen evolution OPC signal.

Photoacoustic assessment of the in vivo genotypical response of corn to toxic aluminium.

An open-cell photoacoustic (OCPA) spectroscopic technique is described which can assess genetically rooted differences in the response of live specimens of corn (Zea Mays L.) to the toxic action of aluminium. Specimens from a susceptible and a tolerant inbred line were examined. The differences in their OCPA in vivo leaf spectra were evident and an interpretation is given based on the genetically controlled response of the inbreds to aluminium toxicity. An earlier discrimination among specimens is obtained with this technique than has been possible so far with previous techniques.

Transport of oxygen and heat in leaves during photosynthesis studied photoacoustically on in vivo samples at low modulation frequencies

Amplitude and phase angle of the photobaric and photothermal signal were measured on in vivo samples of Jequitiba and Copuifera trapezifilia varying the modulation frequency between about 10 and 55 Hz. For both plant species we found that the phase angle of the photobaric signal decreases with increasing modulation frequency whereas the phase angle of the thermal signal increases. The results are interpreted with models recently developed.

Quartz crystal microbalance and photoacoustic measurements in dental photocuring

Photocured dental resins are used extensively in restorative procedures in dentistry. Inadequate curing reduces the lifetime of the dental restoration, and consequently it is essential to precisely measure the polymerisation kinetics. In this study, two techniques, Quartz Crystal Microbalance (QCM) and Photoacoustic Spectroscopy (PAS), were used to monitor the real-time cure and to obtain the optical absorption spectra of resins, respectively. From the PAS measurements, the precise peaks of absorption were identified, and were used as the appropriate wavelength of the photocuring light in the QCM monitoring. The combined use of these techniques allows reliable determination of the duration of the phases of physical and chemical changes that occur during photocuring. Two commercial dental resins were tested, and the results confirmed the advantages of using PAS and QCM to study polymerisation kinetics.