Synthesis of C-Plane Oriented Hexagonal Tungsten Oxide Membranes on Tubular Substrates and Their Acetic Acid/Water Separation Performances

Hexagonal tungsten oxide (h-WO3) membrane is a novel candidate for dehydration of acetic acid (CH3COOH)/water mixtures owing to its molecular sieving property and acidic resistance. Meanwhile, c-plane orientation is an important factor for h-WO3 membranes because the pores of h-WO3 run along its c-axis. However, so far, high c-plane orientation has not been successful on tubular substrates. Here, the effect of synthesis conditions of h-WO3 membranes on tubular substrates against c-plane orientation and CH3COOH/water separation performance are investigated. The h-WO3 membranes were prepared by hydrothermal synthesis from a precursor sol containing various amounts of sodium tungstate (Na2WO4) in the presence of tubular substrates with seeds embedded on their outside surface. The seeding method and the amount of Na2WO4 in the precursor sol significantly affected both crystal orientation and densification of the membrane. A precursor sol with appropriate amounts of Na2WO4 was essential to simultaneously satisfy high c-plane orientation and densification of the membrane while excess Na2WO4 drastically decreased the degree of c-plane orientation. A highly c-plane oriented h-WO3 membrane was successfully obtained under the optimized condition, which exhibited a maximum separation factor of 40.0 and a water permeance of 1.53 × 10−7 mol·m−2·s−1·Pa−1 in a 90:10 wt % CH3COOH/water mixture. The water permeance approximately doubled compared to the previous report, possibly owing to the significantly higher degree of c-plane orientation. Furthermore, it was found that its separation ability can be maintained while stored in 90:10 wt % CH3COOH/water mixture with pH < 0 for more than 500 h

Evaluation of behavior and neuropeptide markers of pain in a simple, sciatic nerve-pinch pain model in rats

Pathomechanisms of injured-nerve pain have not been fully elucidated. Radicular pain and chronic constriction injury models have been established; however, producing these models is complicated. A sciatic nerve-pinch injury is easy to produce but the reliability of this model for evaluating pain behavior has not been examined. The current study evaluated pain-related behavior and change in pain markers in the dorsal root ganglion (DRG) of rats in a simple, sciatic nerve-pinch injury model. In the model, the sciatic nerve was pinched for 2 s using forceps (n = 20), but not injured in sham-operated animals (n = 20). Mechanical and thermal hyperalgesia were measured every second day for 2 weeks using von Frey filaments and a Hargreaves device. Calcitonin gene-related peptide (CGRP), activating transcription factor-3 (ATF-3), phosphorylated p38 mitogen activated protein (Map) kinase (p-p38), and nuclear factor-kappa B (NF-κB; p65) expression in L5 DRGs were examined at 4 and 7 days after surgery using immunohistochemistry. The proportion of neurons immunoreactive for these markers was compared between the two groups. Mechanical (during 8 days) and thermal hyperalgesia (during 6 days) were found in the pinch group rats, but not in the sham-operated animals (p < 0.05); however, hyperalgesia was not significant from days 10 to 14. CGRP, ATF-3, p-p38, and NF-κB expression in L5 DRGs was upregulated in the nerve-injured rats compared with the sham-operated rats (p < 0.01). Our results indicate that a simple sciatic nerve pinch produced pain-related behavior. Upregulation of the pain-marker expression in the nerve-injury model suggested it could be used as a model of pain. However, it was not considered as suitable for long-term studies