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Based on tunable properties, engineered nanoparticles (NPs) hold significant promise for water treatment technologies. Motivated by concerns regarding toxicity and non-biodegradability of some nanoparticles, we explored engineered magnetite (Fe 3 O 4 ) nanoparticles with a biocompatible coating. These were prepared with a coating of rhamnolipid, a biosurfactant primarily obtained from Pseudomonas aeruginosa . By optimizing synthesis and phase transfer conditions, particles were observed to be monodispersed and stable in water under environmentally relevant pH and ionic strength values. These materials were evaluated for U( vi ) removal from water at varying dissolved inorganic carbon and pH conditions. The rhamnolipid-coated iron oxide nanoparticles (IONPs) showed high sorption capacities at pH 6 and pH 8 in both carbonate-free systems and systems in equilibrium with atmospheric CO 2 . Equilibrium sorption behavior was interpreted using surface complexation modeling (SCM). Two models (diffuse double layer and non-electrostatic) were evaluated for their ability to account for U( vi ) binding to the carboxyl groups of the rhamnolipid coating as a function of the pH, total U( vi ) loading, and dissolved inorganic carbon concentration. The diffuse double layer model provided the best simulation of the adsorption data and was sensitive to U( vi ) loadings as it accounted for the change in the surface charge associated with U( vi ) adsorption. 

Context. LDN 1157 is one of several clouds that are situated in the cloud complex LDN 1147/1158. The cloud presents a coma-shaped morphology with a well-collimated bipolar outflow emanating from a Class 0 protostar, LDN 1157-mm, that resides deep inside the cloud. Aims. The main goals of this work are (a) mapping the intercloud magnetic field (ICMF) geometry of the region surrounding LDN 1157 to investigate its relationship with the cloud morphology, outflow direction, and core magnetic field (CMF) geometry inferred from the millimeter- and submillimeter polarization results from the literature, and (b) to investigate the kinematic structure of the cloud. Methods. We carried out optical ( R -band) polarization observations of the stars projected on the cloud to map the parsec-scale magnetic field geometry. We made spectroscopic observations of the entire cloud in the 12 CO, C 18 O, and N 2 H + ( J = 1–0) lines to investigate its kinematic structure. Results. We obtained a distance of 340 ± 3 pc to the LDN 1147/1158, complex based on the Gaia DR2 parallaxes and proper motion values of the three young stellar objects (YSOs) associated with the complex. A single filament of ~1.2 pc in length (traced by the Filfinder algorithm) and ~0.09 pc in width (estimated using the Radfil algorithm) is found to run throughout the coma-shaped cloud. Based on the relationships between the ICMF, CMF, filament orientations, outflow direction, and the hourglass morphology of the magnetic field, it is likely that the magnetic field played an important role in the star formation process in LDN 1157. LDN 1157-mm is embedded in one of the two high-density peaks detected using the Clumpfind algorithm. The two detected clumps lie on the filament and show a blue-red asymmetry in the 12 CO line. The C 18 O emission is well correlated with the filament and presents a coherent structure in velocity space. Combining the proper motions of the YSOs and the radial velocity of LDN 1147/1158 and an another complex, LDN 1172/1174, that is situated ~2° east of it, we found that the two complexes are moving collectively toward the Galactic plane. The filamentary morphology of the east-west segment of LDN 1157 may have formed as a result of mass lost by ablation through interaction of the moving cloud with the ambient interstellar medium.