This study describes a very sensitive fluorescence sensor for the selective nanomolar detection of Ni2+ ions.

Real-time fluorescence measurements have been developed for measuring the fractal dimension d_{f} and critical exponents gamma and beta simultaneously during the sol-gel transition of acrylamide bisacrylamide cross-linking copolymerization. We observed that d_{f} passes through a minimum value of approximately 2.5 at a critical time t_{c} and crossover to 3 above it. The exponents gamma and beta , measured at t_{c} , were found to be around 1.8 and 0.45, respectively. All parameters d_{f} , beta , and gamma measured at the critical point t_{c} agree with three-dimensional percolation results.

No abstract

No abstract

In this study, we synthesized the new kinds of semiconducting polymeric gels having negative (n-type) and positive (p-type) counter ions as charge carriers. The polyacrylamide gel was doped with pyranine (8-hydroxypyrene-1,3,6-trisulfonic acid, trisodium salt), havingions as side groups and Na+ as counter ions, so-called p-type semiconducting gel. The doping process was performed during the polymerization where the pyranine binds to the polymer strands over OH group chemically via radical addition. In a similar way, N-isopropylacrylamide (NIPA) gel was doped with methacrylamidopropyltrimethyl ammonium chloride (MAPTAC), having Cl− as counter ions, so-called n-type semiconducting gel. Here MAPTAC was embedded by copolymerization within the polymer network (NIPA). These semiconducting gels can show different electrical properties by changing the concentration of the doping agents, swelling ratio etc. We have shown that the pn junction, formed by combining p-type and n-type gels together in close contact, rectifies the current similar to the conventional Si and Ge diodes.