Membrane resistance and permselectivity for counter-ions have important roles in determining the performance of cation-exchange membranes (CEMs). In this study, PVA-based polyanions-poly(vinyl alcohol-b-sodium styrene sulfonate)-were synthesized, changing the molar percentages CCEG of the cation-exchange groups with respect to the vinyl alcohol groups. From the block copolymer, poly(vinyl alcohol) (PVA)-based CEMs, hereafter called "B-CEMs", were prepared by crosslinking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations CGA. The ionic transport properties of the B-CEMs were compared with those previously reported for the CEMs prepared using a random copolymer-poly(vinyl alcohol-co-2-acrylamido-2-methylpropane sulfonic acid)-hereafter called "R-CEMs". The B-CEMs had lower water content than the R-CEMs at equal molar percentages of the cation-exchange groups. The charge density of the B-CEMs increased as CCEG increased, and reached a maximum value, which increased with increasing CGA. A maximum charge density of 1.47 mol/dm3 was obtained for a B-CEM with CCEG = 2.9 mol% and CGA = 0.10 vol.%, indicating that the B-CEM had almost two-thirds of the permselectivity of a commercial CEM (CMX: ASTOM Corp. Japan). The dynamic transport number and membrane resistance of a B-CEM with CCEG = 8.3 mol% and CGA = 0.10 vol.% were 0.99 and 1.6 Ωcm2, respectively. The B-CEM showed higher dynamic transport numbers than those of the R-CEMs with similar membrane resistances.
A newly discovered sandstone-dwelling species of the rock gecko, genus Cnemaspis, is described from Santubong National Park, 25 km north of Kuching, southwestern Sarawak, Malaysian Borneo. Molecular phylogenetic analysis confirmed that Cnemaspis puterisantubongae sp. nov. is closely related to other Cnemaspis species in southwestern Sarawak, except for C. kendallii, although these relationships remain unclear. The new species differs from closely related species in having a moderate snout-vent length of up to 66.7 mm; 10-14 precloacal pores in males; 9-14 obviously-convex precloacal pore-bearing scales in females; enlarged, smooth, flat median subcaudal scales; sharp-edged, broad black markings on the trunk dorsum; and a black-gray banding pattern on the posterior part of the original tail, with white median subcaudal scales in males. This discovery of this new species from Santubong National Park, which is highly accessible due to its proximity to Kuching, highlights the need for extensive inventory surveys throughout the national parks of Sarawak.