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In response to the shortage of water resources, multiple processes have been applied to turn wastewater secondary effluent (SE) into potable water. However, trace organic contaminants (TOrCs) and high concentrations of organic matter contained in SE pose a significant challenge to the reclamation. In this manuscript, combined UV-based and biofilm processes were used to treat the SE spiked with ibuprofen (IBU) and clofibric acid (CA). The efficiency of these sequential treatments was characterized in terms of changes in dissolved organic carbon (DOC), absorbance at 254 nm (A254), fluorescence excitation-emission matrix (FEEM), the concentration of IBU and CA, and molecular weight of SE. Parallel factor (PARAFAC) was applied as the analysis method for FEEM of the samples and two fluorescent components were successfully identified: humic-like substances (C1) and protein-like matter (C2). Large reductions in A254, C1, C2, IBU, and CA were observed during the UV-based processes, especially with the addition of H2O2. Nearly 50% of A254, 80% of the component C1 were decreased and almost complete removal of the component C2 and TOrCs was achieved by UV/2.0 mM H2O2 after 90-min treatment. During the oxidation processes, the formation of lower molecular weight (LMW) compounds was detected, and the biodegradability of the organic matters was greatly increased. Although no significant DOC reduction was obtained in UV-based processes, an obvious further DOC reduction (30~60%) was achieved by biofilm treatment following UV-based processes, especially after UV/H2O2 treatments. In the meantime, large amounts of LMW were removed in the biofilm treatment process. This manuscript provides an effective advanced treatment of SE for the removal of DOC and TOrCs, facilitating the wastewater reclamation.

To improve the utilization of sucrose for 2,3-butanediol (2,3-BD) production, four combinations of heterologous energy-conserving sucrose utilization pathways were introduced into Bacillus subtilis Δtet strain (a derivative from B. subtilis 168) and B. subtilis FJ-1 strain (a new isolate in our lab). Results demonstrated that the combination of cscB (encoding sucrose permease) from Escherichia coli and gtfA (encoding sucrose phosphorylase) from Streptococcus mutans showed the most remarkable enhancement for the 2,3-BD production. With sucrose and sugar cane juice as substrate, respectively, the Δtet-CEG strain (B. subtilis Δtet strain containing the energy-conserving sucrose utilization pathway as referred above) showed 36.5% and 24.7% increase in 2,3-BD production than the control Δtet strain, and the FJ-1-CEG strain also produced 23.8% and 44.5% more 2,3-BD than the control FJ-1 strain. The metabolic engineering strategy demonstrated in this study can be extensively applied to other microorganisms for r...

2,3-Butanediol (2,3-BD), especially when it exists in the chirally pure form, is a valuable chemical feedstock with numerous applications in various industries. However, in most cases, the 2,3-BD naturally produced by the microorganism is a mixture of two of the three isomers (d-2,3-BD, l-2,3-BD, and meso-2,3-BD), which has restricted applications and thus a much lower value than the chirally pure one. In this study, we report a new isolate Bacillus spp. FJ-4 strain, which can produce highly chirally pure d-2,3-BD (>99.9%) to high levels, with very high productivity and yield. The composition of the fermentation medium for the strain was sequentially optimized using statistical experimental methodologies. During a fed-batch experiment, 100.0 g/L of d-2,3-BD was produced from 226.8 g/L glucose, with a yield of 0.44 g/g (88.2% of the theoretical maximum). Acetoin was the primary byproduct, and no other byproduct such as lactate, acetate, or ethanol was detected, which would be advantageous for the downstrea...

Cationic polymerizations of isobutylene (IB) with H2O/FeCl3/isopropanol (iPrOH) initiating system were conducted in nonpolar hydrocarbon media, such as n-hexane or mixed C4 fractions at −40 to 20 °C. This cationic polymerization is a chain-transfer dominated process via highly selective β-proton elimination from CH3 in the growing chain ends, leading to formation of highly reactive polyisobutylenes (HRPIBs) with large contents (> 90 mol %) of exo-olefin end groups (structure A). The content of structure A remained nearly constant at about 97 mol % during polymerization and isomerization via carbenium ion rearrangement could be suppressed in nonpolar media. First-order kinetics with respect to monomer concentration was measured for selective cationic polymerization of IB in the mixed C4 fraction feed at −30 °C and the apparent rate constant for propagation was 0.028 min−1. High polymerization temperature (Tp) or [FeCl3] accelerate β-proton elimination or isomerizations and simultaneously decrease selectivity of β-proton abstraction from CH3. Molecular weight decreased and molecular weight distribution (MWD) became narrow with increasing Tp or [FeCl3]. To the best of our knowledge, this is the first example to achieve high quality HRPIBs with near 100% of exo-olefin terminals and relatively narrow MWD (Mw/Mn = 1.8) by a single-step process in nonpolar hydrocarbon media. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4200–4212

Copper coated short carbon fiber reinforced aluminum alloy matrix composites have been prepared with 0.3-1.5 wt% Mg as alloying addition by stir casting. Effect of Mg on the microstructure and mechanical properties of the composites was investigated. The microstructure was observed by scanning electron microscopy and the results show that adding Mg can make the distribution of carbon fibers uniform in the composites, reduce laminated and agglomerated. Tensile test and hardness test were carried out, the results show that the tensile strength and the hardness of the composite is increased by 13% and 8% when Mg content is 0.9 wt%.

The cationic polymerizations of isobutylene (IB) with H2O/FeCl3/dialkyl ether initiating system were conducted in dichloromethane (CH2Cl2) at temperatures from −20 to +20 °C, in which the dialkyl ether includes diethyl ether (Et2O), dibutyl ether (Bu2O) or diisopropyl ether (iPr2O). The highly reactive polyisobutylenes (HRPIBs) with high content of exo-olefin end groups (−CH2−C(CH3)═CH2) 82−91 mol % and acceptable monomodal molecular weight distribution (Mw/Mn = 1.7−2.3) could be successfully synthesized at low concentration of FeCl3 at 0.005 mol·L−1 at 0 or even 10 °C. These results are comparable to those of commercial HRPIBs produced industrially at far below 0 °C. The directly rapid β-proton elimination from −CH3 of the growing chain ends and chain transfer reaction to monomer were dependent on concentration of iPr2O·FeCl3 complex (1:1), concentration of free iPr2O ([free iPr2O] = [iPr2O] − [FeCl3]) if (iPr2O·FeCl3> 1) and polymerization time. The much higher concentration of PIB chains formed in the ...

Dissolved organic matter (DOM) in wastewater can be characterized using fluorescence excitation-emission matrix and parallel factor (EEM-PARAFAC) analysis. Wastewater from animal farms or pharmaceutical plants usually contains high concentration of antibiotics. In this study, the quenching effect of antibiotics on the typical components of DOM was explored using fluorescence EEM-PARAFAC analysis. Four antibiotics (roxarsone, sulfaquinoxaline sodium, oxytetracycline, and erythromycin) at the concentration of 0.5∼4.0 mg/L and three typical components of DOM (tyrosine, tryptophan, and humic acid) were selected. Fluorescence quenching effects were observed with the addition of antibiotics. Among these four antibiotics, roxarsone (2.9∼20.2 %), sulfaquinoxaline sodium (0∼32.0 %), and oxytetracycline (0∼41.8 %) led to a stronger quenching effect than erythromycin (0∼8.0 %). From the side of DOM, tyrosine and tryptophan (0.5∼41.8 %) exhibited a similar quenching effect, but they were higher than humic acids (0∼20.2 %) at the same concentration of antibiotics. For humic acid, a significant quenching effect was observed only with the addition of roxarsone. This might be the first report about the fluorescence quenching effect caused by antibiotics. The results from this study confirmed the interference of antibiotics on the fluorescence intensity of the main components of DOM and highlighted the importance of correcting fluorescence data in the wastewater containing antibiotics.

In the title compound, {[Co(C10H8N2)(H2O)4](C10H8O6)·0.5C10H8N2·2H2O}n, the Co atoms are bridged into a chain by 4,4′-bipyridine units; both the bridging and the uncoordin­ated 4,4′-bipyridine mol­ecules are arranged around inversion centres and are centrosymmetric. Two-dimensional `fishing-net' layers are built up through O—H⋯N hydrogen-bond inter­actions. The diacid anions and uncoordinated water mol­ecules fill the space between the layers. A three-dimensional supra­molecular network is built up by O—H⋯O and O—H⋯N hydrogen-bond inter­actions between water mol­ecules, anions and 4,4′-bipyridine mol­ecules.

The title compound, C15H22O4, obtained from the dehydration of dihydroartemisinin, has retained the endoperoxide bridge of the parent compound along with the C=C bond. The six-membered rings exhibit chair, twist–boat and envelope conformations.

The structure of the title compound, [Pr(C6H4NO2)3(C12H8N2)2(H2O)2]·3H2O, is composed of a discrete neutral Pr complex and solvent water mol­ecules. The PrIII center is nine-coordinate and exhibits a monocapped square-antiprismatic coordination geometry formed by three O atoms of distinct nicotinate groups, four N-atom donors of two 1,10-phenanthroline mol­ecules and two aqua ligands.

The title complex, [Zn(C10H6NO2)2(CH3OH)2], is a neutral mononuclear complex containing a ZnII ion in a six-coordinate environment. The ZnII center, located on a crystallographic center of symmetry, displays a distorted octahedral geometry, with two 2-quinoline­carboxyl­ate and two methanol ligands, all in trans configurations. The complex mol­ecules are linked together by O—H⋯O hydrogen bonds between methanol mol­ecules and carboxyl­ate groups to form a two-dimensional framework.

2-(1-Chloroalkyl)-4,5-dimethyloxazoles were prepared in 84-91% yields by simultaneous reduction and regioselective chlorination of the corresponding unstable N-oxides with POCl3 or SOCl2. Dehydrochlorination of 2-(1-chloroalkyl)-4,5-dimethyloxazoles with potassium hydroxide afforded (E)-2-alkenyl-4,5-dimethyloxazoles in 71-90% yields.

In the title compound, [Ni(H2O)6](C8H6NO4S)2, the NiII atom lies on an inversion center and is six-coordinated in an octa­hedral environment. Cations and anions are linked by O—H⋯O hydrogen bonds into a three-dimensional network.

In the title compound, C18H18N2O22+·2NO3−·3H2O, all bond lengths and angles in the diprotonated 1,3-bis­(4-pyridylmeth­oxy)benzene cation are normal. The mol­ecular skeleton of the cation is approximately planar; the central benzene ring makes dihedral angles of 8.98 (11) and 1.30 (12)° with the two outer pyridine rings. In the crystal structure, an extensive network of inter­molecular of N—H⋯O and O—H⋯O hydrogen bonds stabilizes the packing.

In the title compound, C9H7N3OS, the structure is stabilized by intra­molecular O—H⋯N and inter­molecular C—H⋯O and C—H⋯N hydrogen bonds. The inter­molecular hydrogen bonds link the mol­ecules into a three-dimensional supra­molecular network.

The asymmetric unit of the title compound, [Co(H2O)6](C8H6NO5)2·5H2O, contains one [Co(H2O)6]2+ cation, two C8H6NO5− anions and five uncoordinated water mol­ecules. Cations and anions are linked through O—H⋯O hydrogen bonding involving the uncoordinated water mol­ecules, resulting in a three-dimensional network.

The title compound, C30H46O9, prepared from a mixture of alpha- and beta-dihydroartemisinin, has alpha- and beta-arteether moieties linked via an -O- bridge, so that the molecule is asymmetric about the bridge. The endoperoxide bridges of the parent compounds have been retained in each half of the ether-bridged dimer. The rings exhibit chair and twist-boat conformations.

In the title complex, [CuEu(C19H20N2O4)(NO3)3], the CuII ion is four-coordinated in a square-planar geometry by two O atoms and two N atoms of the deprotonated Schiff base. The EuIII atom is ten-coordinate, chelated by three nitrate groups and linked to the four O atoms of the deprotonated Schiff base.