Complexation of cationic 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin (TMPyP) and negatively charged chemically converted graphene (CCG) sheets was performed by simply mixing the diluted aqueous solutions of both components. During this process, a large bathochromic shift of porphyrin Soret band from 421 to 458 nm was observed, which is attributed to the flattening of TMPyP molecules induced by CCG through electrostatic and pi-pi stacking cooperative interactions. Furthermore, the coordination reaction between TMPyP and Cd(2+) ions was greatly accelerated from 20 h to 8 min under ambient conditions by introducing CCG sheets. On the basis of this phenomenon, we used the complex of TMPyP and CCG as an optical probe for rapid and selective detection of Cd(2+) ions in aqueous media.

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S U M M A R Y1848 specimens were collected systematically from about 900 horizons in the loess profile of Xifeng, Gansu province, China. The magnetostratigraphy is established on the basis of the palaeomagnetic results after thermal cleaning, usually at 300 "C. This result has been found to be generally consistent with previous work in Luochuan. The susceptibility varies regularly with the appearance of loess and palaeosol in the profile and thus could be used as a criterion to classify the loess and palaeosol sequence.

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We use the Onsager principle to derive a two-phase continuum formulation for the hydrodynamics of the electrorheological (ER) fluid, consisting of dielectric microspheres dispersed in an insulating liquid. Predictions of the theory are in excellent agreement with the experiments. In particular, it is shown that whereas the usual configuration of applied electric field being perpendicular to the shearing direction can lead to shear thinning at high shear rates and thus the loss of ER effect, the interdigitated, alternating electrodes configuration can eliminate the shear-thinning effect.

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