Natural amino acids as potential chelators for soil remediation.

The soils contaminated by toxic metals are often remediated using EDTA and similar non-biodegradable chelators. Most chelators are in fact synthetic amino acid derivatives, whereas natural proteinogenic amino acids (PAAs) have not been systematically explored as remediation agents, despite their well-known metal chelating abilities and environmental benefits. Our study represents a comprehensive research exploring 16 structurally and functionally different PAAs as potential remediating agents, applied to 3 different heavy metal-contaminated samples. The study was mostly focused on extracting Cd, Cu, Ni, and Zn. The reaction parameters were screened and optimized. It was found that the efficiencies of extracting Cu, Ni, and Zn by Threonine, Aspartic acid and Histidine were comparable to those by EDTA, whereas non-polar side chain-containing PAAs demonstrated consistently lower PTM extraction rates compared to other PAAs. The sulfur-containing Cysteine appeared to be efficient to extract Cd (to some extent), Ni and Zn, but not Cu, due to chemical reasons. The structure-functional correlations were identified, described, and found to be independent on the specific samples. Possible molecular mechanisms of metal extraction from soils by PAAs are discussed. In contrast to EDTA, the soil-essential elements are almost not extracted by PAAs. This important feature of the PAAs, along with their availability, observed selectivity, competitive efficiency, non-toxicity and even fertilizing properties, make them particularly soil-friendly, and thus, potentially applicable chelators in certain remediation processes.

New insights into chelator recycling by a chelating resin: From molecular mechanisms to applicability.

As part of the project of developing a "green" and highly feasible soil remediation process, recycling an eco-friendly chelating agent, glycine, using Chelex-100 chelating resin, was studied. Two model complexes, copper and nickel glycinates, were tested under various conditions, including equivalent viscosity but different temperature conditions. Two similar complexes demonstrated very different reactivity towards Chelex-100. An in-depth study led to the discovery of unusual metal-dependent mechanisms of the complex-to-resin metal transfer. Particularly, nickel transfer proceeds via a dissociative mechanism, whereas copper transfer does not require pre-dissociation of the complexes, and proceeds via the associative ligand-exchange mechanism. Both processes result in the recovery of the used chelator. The glycine solution was applied on the spiked soil, then recovered on Chelex-100 resin and successfully reused, thus demonstrating a proof of the concept. These findings contribute to the science, strategies, and methodology of both water purification and chelator recycling fields.

Advancing micro-scale cooling by utilizing liquid-liquid phase separation.

Achieving effective cooling within limited space is one of the key challenges for miniaturized product design. State-of-the-art micro-scale cooling enhancement techniques incorporate flow disturbances and boiling to reach high performance. However, these methods face the inherent issues of extra pressure drop, flow instability and dry-out that limits heat flux. Here we demonstrate that substantial cooling capability enhancement, up to 2.5 times, is realized by introducing the phase separation of a triethylamine (TEA)/water mixture at the micro-scale. Our experiments show that the enhancement behavior is closely related to the system's initial composition, temperature, and flow conditions. Moreover, the mixture system exhibits reduced pressure drop after separation, which makes it more promising in serving practical applications. The results reveal new possibilities for liquid coolant selection and provide the experimental foundation for further research in this area.

Pollutant Ground Concentrations of Nonneutrally Buoyant Particles.

A methodology is suggested for the estimation of the mass density and the cumulative ground deposition of a nonvolatile, nonneutrally buoyant, air pollutant (liquid or solid) released from a polluted column (following an explosion caused during routine operation in, e.g., the chemical industry or due to any kind of hostile act) and deposited on the ground via gravitational settling. In many cases, the deposited mass due to gravitational settling constitutes a significant fraction of the original inventory released from the source. Implementation of the methodology in preliminary risk assessments can serve as an efficient tool for emergency planning for both immediate and long-term measures such as evacuation and decontamination. The methodology considers, inter alia, an estimation of the critical particle diameter, particle size, and mass distributions along the polluted column. This methodology was developed to apply in rural regions since proper application of relevant meteorological input data can be accomplished mainly for such areas.

New biodegradable organic-soluble chelating agents for simultaneous removal of heavy metals and organic pollutants from contaminated media.

Advanced biodegradable and non-toxic organic chelators, which are soluble in organic media, were synthesized on the basis of the S,S-ethylenediamine-disuccinate (S,S-EDDS) ligand. The modifications suggested in this work include attachment of a lipophilic hydrocarbon chain ("tail") to one or both nitrogen atoms of the S,S-EDDS. The new ligands were designed and evaluated for application in the Sediments Remediation Phase Transition Extraction (SR-PTE) process. This novel process is being developed for the simultaneous removal of both heavy metals and organic pollutants from contaminated soils, sediments or sludge. The new chelators were designed to bind various target metal ions, to promote extraction of these ions into organic solvents. Several variations of attached tails were synthesized and tested. The results for one of them, N,N'-bis-dodecyl-S,S-EDDS (C24-EDDS), showed that the metal-ligand complexes are concentrated in the organic-rich phase in the Phase Transition Extraction process (more than 80%). Preliminary applications of the SR-PTE process with the C24-EDDS ligand were conducted also on actually contaminated sludge (field samples). The extraction of five toxic metals, namely, Cd, Cu, Ni, Pb and Zn was examined. In general, the extraction performance of the new ligand was not less than that of S,S-EDDS when a sufficient ligand-to-extracted ion ratio (about 4:1 was applied.

The sounds of music in the operating room.

BACKGROUND: Little information is available about the effect of music on the operating room (OR) staff. PURPOSE: The objective of this study was to evaluate the perception of the influence of music on physicians and nurses working in the OR. METHODS: A questionnaire was designed and 250 copies were distributed to the doctors and nurses working in the OR at three hospitals. One hundred and seventy-one returned the completed questionnaire and were included in this study. RESULTS: 63% of the participants listen to music on a regular basis in the OR. Classical music is the most requested (58%) and most of the responders do not choose the type of music according to the type of the procedure. In our study, the nurses were more likely to listen to music and the willingness is higher among the female responders. The desired volume is lower as age increases and 78.9% of the participants claimed that music in the OR makes them calmer and more efficient. CONCLUSION: According to our study, music has a positive effect on the staff working in the operating rooms.