No abstract

On the basis of the varying amplitude and patterns of the (19)F NMR chemical shift of C6F5X (X = F, Cl, Br, I) in the presence of chloride anions, bonding models of C6F5X·Cl(-) complexes were tentatively established, and the relevant binding constants were obtained. Interaction models were also simulated using computational chemistry. The theoretical computations were found to be highly consistent with the results of the experiments. The results show that C6F5Br/C6F5I and Cl(-) were prone to forming C-I/Br···Cl(-) σ-hole bonding complexes with the (19)F NMR signal shifting to higher fields, and the interaction strength of the C6F5I···Cl(-) σ-hole bond was larger than that of C6F5Br···Cl(-); C6F6/C6F5Cl and Cl(-) formed π-hole···Cl(-) bonding complexes with the signal shifting to lower fields, and the interaction strength of C6F6 was larger than that of C6F5Cl. The binding constant of the C6F5I···Cl(-) σ-hole bonding complex is 38.0 M(-1), which is nearly 165- to 345-fold larger than that of the other C6F5X·Cl(-) complexes. On the basis of the above results, solid phase extraction experiments were designed, and the results demonstrated the potential applicability of the C-I···Cl(-) σ-hole bond in separation science.

Room temperature phosphorescence of carbon dots readily engineered by ferric ions in aqueous solution was developed for a novel “off-to-on” approach for cost-effective estimation of ATP level in human blood plasma.

No abstract

The water-soluble luminescent CdSe quantum dots were prepared by ligand exchange with triethanolamine (TEA). Oxygen can reversibly enhance the fluorescence of the synthesized quantum dots (TEA-CdSe-QDs) in aqueous solution. Nitric oxide radical (NO) can react easily with dissolved oxygen in water and was found to have a significant quenching effect on the fluorescence of the TEA-CdSe-QDs. The fluorescence responses were concentration-dependent and can be well described by the typical Stern-Volmer equation. A good linear relationship (R(2 )= 0.9963) was observed over the range 5.92 x 10(-7 )to 1.85 x 10(-5) mol/L nitric oxide. Above this concentration was a second linear region ranging from 2.12 x 10(-5) to 1.12 x 10(-4 )mol/L NO with a gentler slope. The detection limit, calculated following the 3sigma IUPAC criteria, was 3.02 x 10(-7 )mol/L. The interference effect of some common interferents such as nitrite (NO2 (-)), nitrate (NO(3) (-)), glucose and l-ascorbic acid on the detection of NO was negligible for the proposed system, demonstrating the potential utility of this probe for the detection of NO in biological systems. The possible mechanism was also discussed.

No abstract

For translocated animals, behavioral competence may be key to post-release survival. However, monitoring behavior is typically limited to tracking movements or inferring behavior at a gross scale via collar-mounted sensors. Animal-bourne acoustic monitoring may provide a unique opportunity to monitor behavior at a finer scale. The giant panda is an elusive species of Ursid that is vulnerable to extinction. Translocation is an important aspect of the species’ recovery, and survival and recruitment for pandas likely hinge on behavioral competence. Here we tested the efficacy of a collar-mounted acoustic recording unit (ARU) to remotely monitor the behavior of panda mothers and their dependent young. We found that trained human listeners could reliably identify 10 behaviors from acoustic recordings. Through visual inspection of spectrograms we further identified 5 behavioral categories that may be detectable by automated pattern recognition, an approach that is essential for the practical application of ARU. These results suggest that ARU are a viable method for remotely observing behaviors, including feeding. With targeted effort directed towards instrumentation and computing advances, ARU could be used to document how behavioral competence supports or challenges post-release survival and recruitment, and allow for research findings to be adaptively integrated into future translocation efforts.

A new fluorescent probe, 4-N,N-di(2-hydroxyethyl)imino-7-nitrobenzo-2-oxa-1,3-diazole (HINBD) was synthesized in a single step with reasonably good yield. The water-soluble HINBD emits strongly in the visible region (λex  = 479 nm, λem  = 545 nm) and is stable over a wide range of pH values. It was found that vitamin B12 (VB12 ) had the ability to quench the fluorescence of HINBD, and the quenched fluorescence intensity was proportional to the concentration of VB12 . A method for VB12 determination based on the quenching fluorescence of HINBD was thus established. Interference effects of various substances, including sugars, vitamins, amino acids, inorganic cations and some organic substances have been studied. Under optimal conditions, the linear range is 0.0-2.4 × 10(-5)  mol/L. The determination limit is 8.3 × 10(-8)  mol/L. The method was applied to measure VB12 in pharmaceutical preparations with satisfactory results.