The water content of thermo-responsive hydrogels can be drastically altered by small changes in temperature because their polymer chains change from hydrophilic to hydrophobic above their low critical solution temperature (LCST). In general, such smart hydrogels have been utilized in aqueous solutions or in their wet state, and no attempt has been made to determine the phase-transition behavior of the gels in their dried states. Here we demonstrate an application of the thermo-responsive behavior of an interpenetrating polymer network (IPN) gel comprising thermo-responsive poly(N-isopropylacrylamide) and hydrophilic sodium alginate networks in their dried states. The dried IPN gel absorbs considerable moisture from air at temperatures below its LCST and oozes the absorbed moisture as liquid water above its LCST. These phenomena provide energy exchange systems in which moisture from air can be condensed to liquid water using the controllable hydrophilic/hydrophobic properties of thermo-responsive gels with a small temperature change.
Absolute apparent cross sections for electron-impact excitation of helium to the 43D level measured as a function of target-gas pressure (3 x Torr) have been analysed by means of the 'F-cascade model'. proposed by St John and Fowler, in order to study the process of collisional transfer in helium. Because resonance states play an important role, special attention is paid to imprisonment of resonance radiation. Furthermore it is found that scaling of the collisional transfer cross sections with a power of the principal quantum number n leads to results which are inconsistent with the experimental findings. By extrapolation of the apparent 43D cross section to zero pressure we are able to estimate electron-impact excitation cross sections for the 4 l F level.
Hydrogenated amorphous silicon (a-Si:H) was deposited using a triode-type reactor to which an intermittent substrate bias was applied. The total bonded hydrogen content was reduced to 2.9 at.% at a substrate temperature of 200 • C, and a photosensitivity of 5×10 6 with a dark conductivity of 7×10 −11 S/cm was obtained. The defect density measured using a constant photocurrent method was as low as 8.5×10 15 cm −3 . It is suggested that the ion flux intermittently impinging onto the growing film surface causes ion-induced hydrogen desorption and a-Si:H network relaxation.
Surface chemical reactions during reactive ion etching (RIE) of silicon in a CF4+O2 plasma have been investigated by employing in situ Fourier-transform infrared attenuated total reflection (FT-IR ATR) spectroscopy. It is shown that a surface reaction layer with a thickness of 2–4 nm is composed of SiF
X
(X=1, 2, 4 and presumably 3) and SiO
Y
(Y< 2) bonds. The SiF
X
bond concentrations in the surface reaction layer are almost independent of O2 gas concentration in the plasma because they are located mainly at the subsurface layer/Si interface. The etch rate is determined by the oxidized subsurface layer thickness and fluorine radical flux penetrating into the interface region, where the etch products SiF
X
are formed.
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