Appearance Of Anion Research Articles

A Closer Look at Corrugated Au Tips

A series of optical and electron microscopies are utilized in concert to unravel the properties of corrugated metallic tips. While the overall microscopic shapes of the tips dictate their optical resonances and plasmonic field enhancement factors, nanometric structural details govern their tip-enhanced Raman (TER) spectra and images. Using 4-thiobenzonitrile (TBN) as a molecular reporter, spatially resolved TER spectra reveal that optical rectification and molecular charging are among the prominent observables in the tip-tip TER geometry. We show the spurious appearance of anions is driven by highly localized resonances that appear as a result of surface corrugation and their manifestation throughout the course of TER nano-spectroscopy complicates spectral assignments. Overall, nanoscale spatial variations in the TERS spectra suggest that the tip-tip geometry sustains junction plasmons that appear very different from what may be expected from the hybridization of the bulk tip resonances.

Ionic liquid as a medium to remove iron and other metal ions: a case study of the North Kelantan Aquifer, Malaysia

An alternative iron removal treatment method using liquid-liquid extraction with the room-temperature ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, as a solvent medium was studied. The chelating agent 1,10-phenanthroline was used as the extractant. The extraction of Fe(III) and Fe(II) was influenced significantly by the pH of the aqueous phase. The successful removal of iron was achieved; more than 95 % of the initial iron concentration was removed from the groundwater samples. However, detailed research is needed before the ionic liquid method can replace the conventional groundwater treatment protocol because the recovery rate was very low upon reuse (approximately 25–60 %). This low recovery was due to the ion exchange process; the appearance of anions from ionic liquids was also detected in groundwater samples.

Frameworks Tuned by Different Anions via Charge‐Assisted Weak Hydrogen Bonds

AbstractReactions of Co(ClO4)2·6H2O, Cu(NO3)2·3H2O with 4,4′‐dipyridylsulfide (dps) give rise to coordination polymers {[Co(dps)2(DMF)2]·2(ClO4)·2dps}n (1) and {[Cu(dps)2(DMF)(H2O)]·(PF6)·(NO3)}n (2) (DMF = formydimethylamine), respectively. X‐ray diffraction analyses reveal that compound 1 has a one dimensional (1D) chain structure, whereas compound 2 is built of the non‐interpenetrating wave‐like (4, 4) nets. Close inspection of the abundant charge‐assisted weak hydrogen bonds (C‐H···X, X = O, F) between the anions and frameworks in these compounds reveals that the appearance of anion may have a subtle effect on the framework topology. Furthermore, quite few examples of framework holding two different anions only via weak effects as 2 were observed in coordination polymers.

Single anion channels reconstituted from cardiac mitoplasts.

Ion channels from sheep cardiac mitoplast (inverted inner mitochondrial membrane vesicle) preparations were incorporated into voltage-clamped planar lipid bilayers. The appearance of anion rather than cation channels could be promoted by exposing the bilayers to osmotic gradients formed by Cl- salts of large, relatively impermeant, cations at a pH of 8.8. Two distinct activities were identified. These comprised a multisubstate anion channel of intermediate conductance (approximately 60 pS in 300 vs. 50 mM choline Cl, approximately 100 pS in symmetric 150 mM KCl), and a lower-conductance anion channel (approximately 25 or approximately 50 pS in similar conditions), which only displayed two well-defined substates, at approximately 25 and approximately 50% of the fully open state. The larger channels were not simple multiples of the lower-conductance channels, but both discriminated poorly, and to a similar extent, between anions and cations (PCl-/Pcholine+ approximately 12, PCl-/PK+ approximately 8). The lower-conductance channel was only minimally selective between different anions (PNO3-(1.0) = PCl- > PBr- > PI- > PSCN-(0.8)), and its conductance failed to saturate even in high (> 1.0 M) activities of KCl. The channels were not obviously voltage dependent, and they were unaffected by 0.5 mM SITS, H2O2, propranolol, quinine or amitriptyline, or by 2 mM ATP, or by variations in pH (5.5-8.8). Ca2+ and Mg2+ did not alter single channel activity, but did modify single current amplitudes in the lower-conductance channel. This effect, together with voltage-dependent substate behavior, is described in the following paper.