RESUMO
Honeycomb-like porous chitosan (CS) films are attractive tools for developing functional materials for filters, catalyses, adsorbents, biomaterials, etc. A simple method for fabricating honeycomb-like porous CS films without special reagents, facilities, and techniques would make them accessible. Here we introduce an easily available method for fabricating honeycomb-like CS films without a strong acid/base, toxic reagents, or special facilities/techniques. An aqueous solution containing CS and poly(N-isopropylacrylamide) (PNIPAm) was allowed to stand at 25 °C to evaporate water. After 3 days, CS-PNIPAm composite films with homogenously phase-separated PNIPAm particles were obtained. The PNIPAm particles were removed by immersion in methanol, and the resulting films dried under reduced pressure to become honeycomb-like porous CS films. The pore size could be varied in the range of 0.5-3.0 µm by altering the CS concentration and the molecular weight of CS where the pore size was reduced under conditions with stronger interaction between CS molecules. We reveal that the key to success with this system is the decrease of lower critical solution temperature (LCST) of PNIPAm with water evaporation. In addition, we confirmed the removed PNIPAm was recyclable in this system. Furthermore, we found this method was also applicable to alginate. The proposed facile method for fabricating honeycomb-like porous polymeric films could provide various functional porous materials.
RESUMO
An electrotactile display is a tactile interface composed of skin surface electrodes. The use of such a device is limited by the variability of the elicited sensation. One possible solution to this problem is to monitor skin electrical impedance. Previous studies revealed a correlation between impedance and threshold, but did not construct real-time feedback loops. In this study, an electrotactile display was constructed using a 1.45 µs feedback loop. Real-time pulse width modulation was proposed, and the relationship between skin resistance and absolute threshold was measured to find a function for determining a suitable pulse width from skin resistance. An evaluation experiment revealed that the proposed algorithm suppressed spatial variation and reduced temporal change.
RESUMO
[reaction: see text] When carbonyl compounds were allowed to react with phenyl trimethylsilyl selenide and tributylstannyl hydride in the presence of a catalytic amount of AIBN as a radical initiator, the hydrosilylation of the carbonyl compounds efficiently proceeded to give the corresponding silyl ethers in moderate to good yields.
RESUMO
A 16-year-old girl who had been treated for B-precursor acute lymphoblastic leukemia (ALL) presented with a mass in the left orbit as an isolated relapse. Five years earlier, she had undergone chemotherapy that promptly resulted in a complete remission. For prophylaxis of central nervons system leukemia, the patient received cranial radiotherapy (18 Gy) with shielding of the orbit and 15 cycles of intrathecal MTX and prednisolone. Cerebrospinal fluid analysis did not detect infiltration during the treatment course. Exophthalmos of the eft eye and hyperemia of the conjuctiva developed 15 months after therapy. Computed tomography showed a retro-orbital mass behind the left eye. Though bone marrow aspiration was negative, biopsy specimens from the mass disclosed the infiltration of CD10-positive leukemic blasts. After 8 courses of chemotherapy, 5 cycles of intrathecal MTX, and orbital irradiation (24 Gy), the mass disappeared. All relapse as an isolated retro-orbital mass is very rare, and only 3 cases have been reported to date.