Encapsulation of iron nanoparticles with magnesium hydroxide shell for remarkable removal of ciprofloxacin from contaminated water.

The rapid evolution of antimicrobial resistant genes (AMRs) in water resources is well correlated to the persistent occurrence of ciprofloxacin in water. For the first time, encapsulated nanoscale zerovalent iron (nZVI) with a shell of magnesium hydroxide (Mg/Fe0) was used to adsorb ciprofloxacin from water. Optimization of the removal conditions exhibited that 5% was the optimum mass ratio between magnesium hydroxide and nZVI [Mg(OH)2/nZVI)] as more than 96% of 100 mg L-1 of ciprofloxacin was removed. In addition, 0.5 g L-1 of Mg/Fe0 showed an extraordinary performance in removing ciprofloxacin over a wide range of pH (3-11) with removal efficiencies exceeded 90%. Kinetic analysis displayed that the kinetic data was well described by both Pseudo first-order and second-order models. Also, the equilibrium data was well fitted by Freundlich isotherm model. In addition, thermodynamic analysis evidenced that the removal of ciprofloxacin by Mg/Fe0 was exothermic, and spontaneous. The experiments also revealed that physisorption and chemisorption were the responsible mechanisms for ciprofloxacin removal. The proposed treatment system remediated 10 litters of 100 mg L-1 of ciprofloxacin solution with 100% overall removal efficiency. This treatment system could be a promising and practical solution to decrease ciprofloxacin concentration in different water bodies.

Magnetic zeolite synthesis for efficient removal of cesium in a lab-scale continuous treatment system.

Radioactive cesium was resealed to the environment as a result of many nuclear incidents. An effective treatment system is urgently needed to safely handle radioactive cesium-contaminated waters. Based on nanoscale zerovalent iron (nZVI) and zeolite, nine adsorbents were synthesized and applied to remove cesium from aqueous solutions. Magnetic zeolite composite (Ze/Fe0) was selected as the ideal adsorbent for treating cesium contaminated waters in a lab-scale continuous treatment system (LSCTS). The optimization process of the (Ze/Fe0) composite revealed that 1:1 is the optimum mass ratio between zeolite and nZVI. Furthermore, the optimization process proved that the initial pH and temperature have no significant effect on the adsorption of cesium by (Ze/Fe0) composite and the optimum dosage of (Ze/Fe0) composite is 5 g L-1. XRD and SEM results showed that the (Ze/Fe0) composite has an irregular shape with a poor crystalline structure. Kinetic and equilibrium data were best described by pseudo second order and Freundlich isotherm models. Seawater and groundwater experiments illustrated that the removal of cesium by (Ze/Fe0) composite was inhibited due to the existence of competing cations. Eight cycles of LSCTS were performed to examine the performance of (Ze/Fe0) composite in treating continuous streams of cesium contaminated waters. In all cycles except the cycle of treating contaminated seawater, LSCTS succeed to treat continuous flows of 1 mg L-1 cesium contaminated water with 100% overall removal efficiency. For treating contaminated seawater, pre-treatment unit is required to reduce the salinity of the contaminated seawater before staring the treatment process.

Donor-Acceptor π-Conjugated Enamines: Functional Group-Compatible Synthesis from Amides and Their Photoabsorption and Photoluminescence Properties.

High functional group compatibility of iridium-catalyzed synthesis of enamines from amides and 1,1,3,3-tetramethyldisiloxane (TMDS) realized facile access of a series of donor (D)-π-acceptor (A)-conjugated enamines, in which enamine behaves as a donor functional group. The amide precursors containing reducible functional groups, such as halogen, carbonyl, and nitro groups, underwent reaction with TMDS to give the corresponding enamines in high yields. In most cases, chemoselective hydrosilane reduction of the amide group occurred while other reducible groups remained intact. Absorption and emission properties including solvatochromic behavior for the resulting D-π-A-conjugated enamines were determined using UV-visible and fluorescent spectra, which provided an understanding of the donor properties of the CH═CHNPh2 group and photofunctional properties of the D-π-A conjugated enamines as a fluorescent dye. Maximum absorption wavelength (λabs) of p-ZC6H4CH═CHNPh2 was predictable from λabs of p-ZC6H4NPh2, which was supported by density functional theory calculations. Some of the D-π-A-conjugated enamines showed fluorescence with moderate fluorescence quantum yields (Φfl). Of interest are unusually emissive π-conjugated enamines containing a nitro group, which generally behaves as strong quenchers of fluorescence. The additive effect of B(C6F5)3 resulted in significant red shifts of λabs and λfl. In some cases, high Φfl was observed in the solution state.

Remarkably high catalyst efficiency of a disilaruthenacyclic complex for hydrosilane reduction of carbonyl compounds.

A disilaruthenacyclic complex (1) showed extremely high catalytic activity for hydrosilane reduction of aldehydes and ketones to silyl ethers and secondary and tertiary amides to the corresponding amines. An σ-CAM mechanism was proposed to explain the activity.

Disilaruthena- and Ferracyclic Complexes Containing Isocyanide Ligands as Effective Catalysts for Hydrogenation of Unfunctionalized Sterically Hindered Alkenes.

Disilaferra- and disilaruthenacyclic complexes containing mesityl isocyanide as a ligand, 3' and 4', were synthesized and characterized by spectroscopy and crystallography. Both 3' and 4' showed excellent catalytic activity for the hydrogenation of alkenes. Compared with iron and ruthenium carbonyl analogues, 1' and 2', the isocyanide complexes 3' and 4' were more robust under the hydrogenation conditions, and were still active even at higher temperatures (∼80 °C) under high hydrogen pressure (∼20 atm). The iron complex 3' exhibited the highest catalytic activity toward hydrogenation of mono-, di-, tri-, and tetrasubstituted alkenes among currently reported iron catalysts. Ruthenium complex 4' catalyzed hydrogenation under very mild conditions, such as room temperature and 1 atm of H2. The remarkably high catalytic activity of 4' for hydrogenation of unfunctionalized tetrasubstituted alkenes was especially notable, because it was comparable to the activity of iridium complexes reported by Crabtree and Pfaltz, which are catalysts with the highest activity in the literature. DFT calculations suggested two plausible catalytic cycles, both of which involved activation of H2 assisted by the metal-silicon bond through σ-bond metathesis of late transition metals (oxidative hydrogen migration). The linear structure of M-C≡N-C (ipso carbon of the mesityl group) played an essential role in the efficient hydrogenation of sterically hindered tetrasubstituted alkenes.

Theoretical Study of the Catalytic Hydrogenation of Alkenes by a Disilaferracyclic Complex: Can the Fe-Si σ-Bond-Assisted Activation of H-H Bonds Allow Development of a Catalysis of Iron?

The mechanisms associated with the hydrogenation of alkenes catalyzed by the iron complex Fe(cis-CO)2{o-(SiMe2)2C6H4}2(H)2 (1) were investigated by DFT calculations. The complex 1 has a structure in which the iron center is bonded to four silicon atoms and two hydrides. Secondary Si···H···Si interactions were also observed. The exchange of a 1,2-bis(dimethylsilyl)benzene ligand with ethylene and hydrogen gives a disilaferracycle bearing η2-(CH2═CH2) and η2-H2 ligands. The catalytic cycle initiated from the disilaferracycle involves cleavage of a H-H linkage assisted by an Fe-Si bond to form Fe-H and η1-(H-Si) moieties (step 1), hydrogen migration from the Fe-H group to the η2-(CH2═CH2) ligand which accomplishes the insertion of ethylene into the Fe-H bond (step 2), and reaction of the resulting ß-agostic ethyl moiety with the η2-(H-Si) group to form ethane on the iron atom (step 3). The octahedral geometry of 1 as well as the presence of π-acidic CO ligands and Fe-Si σ-bonds contributes to all of the catalytic intermediates and the transition states being in the low-spin state. Steps 1 and 3 correspond to the σ-complex-assisted metathesis (σ-CAM) mechanisms proposed by Perutz and Sabo-Etienne, suggesting that these mechanisms can assist in the design of iron-based hydrogenation catalysts operating under mild conditions.

Non-Precious-Metal Catalytic Systems Involving Iron or Cobalt Carboxylates and Alkyl Isocyanides for Hydrosilylation of Alkenes with Hydrosiloxanes.

A mixture of an iron or a cobalt carboxylate and an isocyanide ligand catalyzed the hydrosilylation of alkenes with hydrosiloxanes with high efficiency (TON >10(3)) and high selectivity. The Fe catalyst showed excellent activity for hydrosilylation of styrene derivatives, whereas the Co catalyst was widely effective in reaction of alkenes. Both of them catalyzed the reaction with allylic ethers. Chemical modification and cross-linking of silicones were achieved by choosing the right catalyst and reaction conditions.

Potentially lethal pharyngolaryngeal edema with dyspnea in adult patients with mumps: A series of 5 cases.

In this article we describe 5 rare cases of mumps-associated pharyngolaryngeal edema. To the best of our knowledge, this report includes the first case of mumps-associated pharyngolaryngeal edema in a patient who had previously received mumps vaccination, and these cases represent the sixth report of mumps-associated pharyngolaryngeal edema in the English literature. All 5 of our patients with mumps infection were adults and manifested airway stenosis due to pharyngolaryngeal edema. This edema responded favorably to steroid treatment without tracheotomy. We conclude that a pharyngolaryngeal examination is recommended for patients with mumps infection. Steroid treatment is usually effective against pharyngolaryngeal edema; however, in certain cases tracheotomy may be inevitable.

Sensorineural Hearing Loss due to Air Bag Deployment.

Deployment of the air bag in a passenger vehicle accident rarely causes otologic injuries. However, sensorineural hearing loss induced by air bag deployment is extremely rare, with only a few cases reported in the English literature. A 38-year-old man involved in a traffic accident while driving his car at 40 km/hour presented with right sensorineural hearing loss and tinnitus, without associated vertigo. Pure-tone audiometry demonstrated elevated thresholds of 30 dB and 25 dB at 4 kHz and 8 kHz, respectively, on the right side. Air bag deployment in car accidents is associated with the risk of development of sensorineural hearing loss.