The surface tension of aqueous solutions of seven polyethylene oxide)-Z>Zoc&-poly(propylene oxide)-6Zoefc-poly(ethylene oxide) (PEO-PPO-PEO) Pluronic copolymers, covering a wide range of molecular weights (3400-14600) and PPO/PEO ratios (0.19-1.79), was determined over the 10-5-10% w/v concentration range, at two temperatures (25 and 35 °C). Two breaks (changes in slope) were observed in the surface tension vs log concentration curve for most of the copolymers. The low-concentration break, occurring at bulk copolymer concentrations of approximately 10-3%, is believed to originate from rearrangement of the copolymer molecules on the surface at complete coverage of the air/water interface. The breaks at the high-concentration part of the surface tension curve occurred at concentrations that correspond to the critical micellization concentration values as determined by a dye solubilization technique. The surface area per copolymer molecule, A, increased as a function of the number of EO segments, ZVeo, obeying a scaling law (A « ZVeo1/2) similar to that of lower molecular weight C¿E, nonionic surfactants. The surface activity of PEO-PPO-PEO block copolymers was compared to that of a PPO-PEO-PPO block copolymer and a PEO-PPO random copolymer and literature values for PEO and PPO homopolymers, in an attempt to probe the effect of molecular architecture on the orientation of the copolymer at the air/water interface. The presence of the PPO block in the center of the copolymer molecule resulted in a copolymer headgroup (PEO) surface area smaller than that of the PEO homopolymer of comparable molecular weight, indicating desorption of PEO segments from the air/water interface and/or tightly packed segments.

The formation of a surface-damaged layer of gate SiO2 induced by exposure to plasma for gate etching led to the increase in etch rate of SiO2 during HF wet treatment. The effects of vacuum ultraviolet (VUV) photons from various gas plasmas generated by an electron cyclotron resonance (ECR) plasma system and a helicon plasma system were evaluated. It was found that the depth of the damaged layer depends on the energy and penetration depth of VUV radiation. The damaged layer grew exponentially with distance from the surface and was extremely disordered, making it more susceptible to the HF etchant.

UV radiation during plasma processing affects the surface of materials. Nevertheless, the interaction of UV photons with surface is not clearly understood because of the difficulty in monitoring photons during plasma processing. For this purpose, we have previously proposed an on-wafer monitoring technique for UV photons. For this study, using the combination of this on-wafer monitoring technique and a neural network, we established a relationship between the data obtained from the on-wafer monitoring technique and UV spectra. Also, we obtained absolute intensities of UV radiation by calibrating arbitrary units of UV intensity with a 126 nm excimer lamp. As a result, UV spectra and their absolute intensities could be predicted with the on-wafer monitoring. Furthermore, we developed a prediction system with the on-wafer monitoring technique to simulate UV-radiation damage in dielectric films during plasma etching. UV-induced damage in SiOC films was predicted in this study. Our prediction results of damage in SiOC films shows that UV spectra and their absolute intensities are the key cause of damage in SiOC films. In addition, UV-radiation damage in SiOC films strongly depends on the geometry of the etching structure. The on-wafer monitoring technique should be useful in understanding the interaction of UV radiation with surface and in optimizing plasma processing by controlling UV radiation.

It is desirable to increase the flavonoid contents of postharvest vegetables since flavonoids play a beneficial role in human health promotion. In the present study, we show that postharvest vegetables increasingly produced flavonoids when irradiated with light near the absorption wavelength of flavonoids in the plant. Three-day exposure to UV-B for 5 min, 98 μmol m⁻² s⁻¹ per day, increased the contents of jaceidin in spinach, kaempherol glycoside in radish sprout, apigenin glycosides in parsley, and isovitexin in Indian spinach after 6 days of storage in a refrigerator, compared to the contents in plants without irradiation. Six days of storage of unripe green strawberry under green light for 5 min, 98 μmol m⁻² s⁻¹ per day, enabled them to mature and turn red, accompanied by 3.5-fold increased contents of pelargonidin. Elucidation of the mechanism in parsley found the stimulating expression of the flavonoid synthesis gene, PAL, C4H, 4CL, CHS, and FNS, 6 h after exposure to single irradiation with UV-B for 5 min, and the higher expression was maintained for 24 h. After 3 days irradiation during 6 days of storage, parsley did not show adverse changes in the contents of ascorbic acid, β-carotene, chlorophyll, and moisture.

A desiccation-tolerant cyanobacterium, Nostoc commune, shows unique responses to dehydration. These responses are: (i) loss of PSII activity in parallel with the loss of photosynthesis; (ii) loss of PSI activity; and (iii) dissipation of light energy absorbed by pigment-protein complexes. In this study, the deactivation of PSII is shown to be important in avoiding photoinhibition when the Calvin-Benson cycle is repressed by dehydration. Furthermore, our evidence suggests that dissipation of light energy absorbed by PSII blocks photoinhibition under strong light in dehydrated states.