Studies on syntheses and permeabilities of special polymer membranes. 40. Formation conditions of finger-like cavities of cellulose nitrate membranes

The permeation characteristics for polymer aqueous solution and asymmetric structure of cellulose nitrate membranes, in particular the finger-like cavity in the back sponge layer of these membranes, were investigated by changing the preparation conditions of the membranes— the casting solvent, evaporation period, and gelation medium. The formation of the finger-like cavity was dependent on absorption of a water molecule into the casting mixture from the atmosphere during the solvent evaporation process and the exchange velocity between the casting solvent and the gelation medium. The mechanism and conditions for the formation of a finger-like cavity in cellulose nitrate membranes were discussed.     

Ultralow resistivity in the surface direction of LB heterofilms

LB heterofilms of double layer consisting of arachidic acid and 2-pentadecyl-7, 7′, 8, 8′-tetracyanoquinodimethane (C₁₅ · TCNQ) LB films were sandwiched between Al and Au thin evaporated films. Such layer structures of Al/LB heterofilm/Au were deposited on the SiO₂ insulating film of silicon wafters. Resistance in the surface direction of the above layer structure was measured by the four-point probe technique. As a result, very low resistance of 10^?2 ～ 10^?3 Ω was obtained by the electrode system of gap 3.3 mm with width 10 mm. It was clarified in the experiments that the current flowed through the LB heterofilms of about 200 ～ 30 Å in thickness; accordingly the resistivity of LB heterofilms was calculated to be 10^?8 ～ 10^?9 Ω cm. Such a value of resistivity was much smaller than the metal resistivity of 10^?5 Ω cm. Furthermore, the current through the LB film, increased up to 1.3A, was equivalent to the very high current density of 4.1 ～ 10⁵ A/cm². However, the resistance was increased suddenly by 10⁶ times at that time and the current was decreased to 3 ～ 10^?4 A. Such a switching phenomenon could be observed repeatedly. The ultraflow resistance and the very high current density observed in the LB heterofilms will be explained by the model of the potential well filled with electron gas which was generated in the LB hetero-film by the polarization of C¹⁵ · TCNQ LB film.     

Role of nitric oxide in the development of tolerance and sensitization to behavioural effects of phencyclidine in mice

1. To determine whether nitric oxide (NO) was involved in tolerance and sensitization to the effects of phencyclidine (PCP), we examined NO synthase activity and the number of NADPH-diaphorase (NADPH-d)-positive cells in discrete brain regions of saline-, acute PCP- and repeated PCP-treated mice. We also investigated the effects of a NO synthase inhibitor, NG-nitro-L- arginine methyl ester (L-NAME), on the behavioural changes induced by repeated PCP treatment in mice. 2. Acute PCP (1, 3, and 10 mg kg-1, s.c.) treatment induced dose-dependent hyperlocomotion, motor incoordination and stereotyped behaviours, consisting of sniffing, head movement and ataxia in mice. 3. In mice treated repeatedly with PCP (1, 3, and 10 mg kg-1 day-1), s.c., once a day for 14 days), the sniffing, head movement, ataxia and motor incoordination induced by PCP were attenuated (indicating the development of tolerance to these behaviours), whereas the hyperlocomotion induced by PCP was potentiated (indicating the development of sensitization to hyperlocomotion). The development of tolerance and sensitization to PCP-induced behaviours in the repeated PCP-treated mice was more marked at the dose of 10 mg kg-1 day-1) than at other doses. 4. NO synthase activity in the cerebral cortex and cerebellum, but not in the striatum and hippocampus, was significantly decreased by acute PCP (10 mg kg-1) treatment in comparison with saline treatment, and such changes in activity in the cerebral cortex and cerebellum were reversed by repeated PCP treatment (10 mg kg-1 day-1). 5. The number of neurones containing NADPH-d reactivity in the cerebral cortex, nucleus accumbens, and striatum of acute and repeated PCP-treated mice showed no change in comparison with saline-treated mice. 6. Tolerance to PCP (10 mg kg-1 day-1)-induced ataxia and motor incoordination was significantly attenuated by combined treatment with L-NAME (50 mg kg-1 day-1 i.p.). 7. Sensitization to PCP-induced hyperlocomotion was further enhanced by combined treatment with L-NAME (50 mg kg-1 day-1). However, NG-nitro-D-arginine methyl ester (D-NAME, 50 mg kg-1 day-1, i.p.), a less active enantiomer of L-NAME, had no effect, suggesting a stereospecific mechanism. 8. The PCP-induced behaviours in animals that had exhibited tolerance and sensitization to PCP (10 mg kg-1 day-1) were not influenced by acute L-NAME (5 and 50 mg kg-1, i.p.) or D-NAME (50 mg kg-1, i.p.) treatment. 9. These results suggest that NO may play an important role in the development, but not in the maintenance, of tolerance and sensitization to the effect of PCP in mice.     

Methylsterol compositions of 19 vegetable oils

The unsaponifiables from 19 vegetable oils were divided into 4-methylsterol fraction, triterpene alcohol fraction and two other fractions by thin layer chromatography. The 4-methylsterol and triterpene alcohol fractions were analyzed by gas liquid chromatography, and identification of major components was carried out by gas liquid chromatography and combined gas chromatography-mass spectrometry. Gramisterol(24-methylenelophenol), citrostadienol and obtusifoliol were present in all oils, and the presence of a 4-methylsterol, presumably cycloeucalenol, was indicated in most of the oils. Cycloartenol and 24-methylenecycloartanol were found as common triterpene alcohols in all oils, and the occurrence of cyclobranol(24-methylcycloartenol), cycloartanol, and α- and β-amyrins was demonstrated in most of the oils.     

Researches on air shutter for fire defence

Large amounts of smoke and toxic gases, generated at the beginning of a fire and spreading rapidly through a building, result in the death of individuals. In order to keep casualties to the minimum, it is necessary to prevent the diffusion of smoke or toxic gas. Fire-doors or fire-screens are available for this purpose, but these create obstructions to exits.In this paper, the air shutter, dependent upon the push-pull principle, which has the effect of controlling the air flow of the surrounding area, is suggested as a means of defence against fire. The function of the air shutter is closely examined, and a theoretical and experimental investigation of the effect of smoke flow on the shutter has been undertaken.As a consequence of this investigation, it is clear that the air shutter is very effective in excluding smoke or toxic gas, and it might prove to be a practical proposition.     

The ability of gallate and pyrogallol moieties of catechins to inhibit P-glycoprotein function

The role of structure–activity relationships in the ability of catechins to inhibit P-glycoprotein (P-gp) function was investigated with respect to gallate and pyrogallol moieties. Experiments using octyl derivatives of gallic acid indicated that the gallate moiety required the catechol group and a neighboring carbonyl group to inhibit P-gp. On the other hand, the pyrogallol moiety appeared to require three hydroxyl groups to inhibit P-gp, according to comparisons between (−)-epicatechin gallate (ECG) and (−)-epigallocatechin gallate (EGCG). The difference in the number of hydroxyl groups that gallate or pyrogallol moieties required for P-gp inhibition, was due to the presence of a carbonyl group. The P-gp inhibition by catechins was restricted by their hydrophobicity. The pyrogallol moiety of EGC did not appear to inhibit P-gp because of its low hydrophobicity. The P-gp inhibitory activity of EGCG was speculated to be increased by the addition of long carbon chains to the C3″of gallate moieties.     

Dry Machining Tool Design via Chlorine Ion Implantation

DRY MACHINING is a keyword for manufacturingand production science in the twenty-first century,which requires significant reduction of environmentalburden and COi emission11.In the modern high-speedwet and semi-dry machining processes,huge amountsof lubricants and cleansing agents are wasted in dailyproduction2).Among various proposals aiming at thedry machining3"5>,in-situ formation of tribo-filrns mustbe an important concept to make dry machining tools.Authors have pointed out the impor…