Phase retrieval of a Kolmogorov phase screen from very sparse data using four binary masks.

We investigate experimentally the phase retrieval of a Kolmogorov phase screen from very sparse data by modulating its amplitude with four binary masks and compare the retrieved phase screen to the ground truth measured with a surface profiler. Previously, we have shown in simulations that this kind of modulation can be successfully used for the phase retrieval of a Kolmogorov phase screen. After subtracting the ground truth from the retrieved phase screen, the root-mean-square error decreased from 0.14 µm to 0.10 µm. We conclude that a Kolmogorov phase screen can be recovered using simple modulation and very sparse data.

Effect of ozone treatment on the microstructure, chemical composition and sensory quality of apple fruits.

The aim of this study was to assess the effect of O3 treatment on the quality of different cultivars of apples ( Malus domestica Borkh.). Apples were stored for six months at different concentrations of ozone. During the research, minor differences between ozone-treated and control fruits were found in terms of cell integrity and epicuticular wax structure. Ozone application for apple treatment could accelerate the natural ageing of the waxes found on the surface of apples, thereby reducing the thickness of the waxes. The rate of degradation for the epicuticular wax was found to be cultivar dependent. After six months of storage, the ozonation process prevented the decay of 'Iedzenu', 'Auksis' and 'Belorusskoje Malinovoje' apple cultivars, but it accelerated damage in the 'Gita' apple cultivar. A positive impact of ozone during long-term storage was found regarding flesh firmness of 'Iedzenu' apple cultivar samples subjected to O3 exposure at concentrations of 0.8 ppm and 3.0 ppm. In other cultivars of apples, significant differences between ozonation and cold storage (control) were not found. In general, ozone treatment has a potential to be applied in order to maintain the sensory quality and biologically active compound level in apples during six-month storage; however, the degree of effectiveness depends both on the cultivar and on the concentration of ozone.

Poling induced mass transport in thin polymer films.

In this study we report investigation of the polymer film morphology modifications during their corona poling for fabrication of nonlinear optically (NLO) active materials. We demonstrate that at certain poling conditions surface and spatial inhomogeneities in the poled area of the sample appear. Densities of the inhomogeinities depend on the strength of the poling field, the sample temperature during the poling, and the prepoling conditions. Optimization of the poling conditions directed toward avoiding surface modifications enables us to increase the overall observable effective nonlinearity of the sample up to 10 times. To investigate, understand, and eventually explain the formation of the spatial and surface structure inhomogeinites in the poled material we have used optical, second harmonic, and scanning electron microscope measurements, as well as the conductivity measurements of the thin films. We present results of poled polymer host-guest films where (dimethylamino)benzylidene-1,3-indandione and low dipole moment 2,2',2″-(4,4',4″-nitrilotribenzylidene)triindan-1,3-dione were used as guests in poly(methyl methacrylate), polystyrol, and polysulfone matrixes doped at 10 wt %.