Cucurbituril: At the Interface of Small Molecule Host–Guest Chemistry and Dynamic Aggregates

The remarkable guest binding behavior of the synthetic receptors, cucurbit[n]uril, has gained tremendous attention over the past few decades. The stronger and more selective encapsulation of small guests has opened up the possibility to develop multi-component, dynamic yet controlled supramolecular aggregated architectures for a wide variety of applications. Isolation of larger homologues and derivatives have expanded the scope further, and interest has grown exponentially. Applications of these unique synthetic receptors presently range from polymeric smart materials and wet nanotechnology to sensing and protein conjugation. This review highlights such examples from recent literature on the development of new dynamic supramolecular aggregates and composites using cucurbituril host–guest chemistry.     

The use of Bassia indica for salt phytoremediation in constructed wetlands

The treatment and reuse of wastewater in constructed wetlands offers a low-cost, environmentally-friendly alternative for common engineered systems. Salinity in treated wastewater is often increased, especially in arid and semi-arid areas, and may harm crops irrigated from wetlands. We have strong evidence that halophyte plants are able to reduce the salinity of wastewater by accumulating salts in their tissues. Bassia indica is an annual halophyte with unique adaptations for salt tolerance. We performed three experiments to evaluate the capability of B. indica for salt phytoremediation as follows: a hydroponic system with mixed salt solutions, a recirculated vertical flow constructed wetland (RVFCW) with domestic wastewater, and a vertical flow constructed wetland (VFCW) for treating goat farm effluents. B. Indica plants developed successfully in all three systems and reduced the effluent salinity by 20-60% in comparison with unplanted systems or systems planted with other wetland plants. Salinity reduction was attributed to the accumulation of salts, mainly Na and K, in the leaves. Our experiments were carried out on an operative scale, suggesting a novel treatment for green desalination in constructed wetlands by salt phytoremediation in desert regions and other ecosystems.     

Removal of chromium from aqueous solutions by treatment with fibrous carbon electrodes: column effects

The continuous removal of toxichexavalent chromium from contaminated solutions by means of a graphite felt based electrochemical column was studied. The process is based on anin situ generation of appropriate pH gradients which allows both rapid reduction to Cr³⁺ and its precipitation within the electrode bed. Conditions for the attainment of low (<25 p.p.b.) effluent concentrations as well as longitudinal concentration distribution of the precipitate and maximum loading capacities are presented. Treatment schemes involving two separate columns or a dual function column are also discussed.     

Inhalation by nebulization of albuterol-ipratropium combination (Dey combination) is superior to either agent alone in the treatment of chronic obstructive pulmonary disease. Dey Combination Solution Study Group

Combination bronchodilator therapy for chronic obstructive pulmonary disease (COPD) potentially can provide increased benefit over single-agent therapy. The objective of this double-blind, randomized, positive-control trial was to determine the effectiveness of an albuterol-ipratropium solution aerosol combination (Dey combination solution, Dey LP, Napa, Calif., USA) compared with solution aerosols of both component medications administered alone in patients with COPD. The trial consisted of a 6-week, 3-period crossover phase followed by a 6-week parallel phase during which patients self-administered study medications by inhalation from a nebulizer. A total of 863 patients were initially randomized to each of the six possible treatment sequences of the three study medications in the crossover phase and received each study medication in turn for a 2-week period. Patients continued to receive the same treatment administered during the last 2-week period of the crossover phase for an additional 6 weeks in the parallel phase. Assessment of 1-second forced expiratory volume (FEV1) curves before and after dosing on the last day of each 2-week period indicated that the combination was superior to either single agent in peak effect and area under the curve up to 8 h after dosing (FEV1-AUC0-8), in both phases of the trial. The use of Dey combination during the crossover phase resulted in 24% more improvement in peak FEV1 than was seen with albuterol alone (p < 0.001), and 37% more than was seen with ipratropium alone (p < 0.001). Similarly, when examining FEV1-AUC0-8, Dey combination resulted in 30% more improvement than was seen with albuterol alone (p < 0.001), and 32% more than was seen with ipratropium alone (p < 0.001). The combination affords a convenient dosing regimen and incorporates enhanced benefit without compromising the safety profile of either component agent.     

Graphite felt as an efficient porous electrode for impurity removal and recovery of metals

The properties of graphite felt as an efficient flow-through or flow-by electrode are demonstrated by the removal of traces of mercuric ions from aqueous electrolyte solutions. A simple and direct method is suggested for the determination of the concentration-distribution profile of the electro-deposit on the electrode. The data are compared to those obtained for electrodes used by other authors. It is concluded that mass transport and other properties are much better for the graphite felt than for the other electrodes, thus making it attractive for the use in electrochemical reactors.     

Three-part auctions versus self-commitment in day-ahead electricity markets

We examine the economic consequences of a bid-based security-constrained centralized unit commitment paradigm based on three-part offers, which is the prevalent day-ahead market-clearing mechanism in restructured electricity markets in the United States. We then compare this approach with an energy-only auction with self-commitment (such as in Australia) addressing efficiency and pricing as well as the tradeoff between coordination losses and incentives to bid truthfully.