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Transient Stability is the capability of a system to be able to return to its normal state after experiencing large disturbances. The static var compensator (SVC) is a shunt device of the flexible AC transmission systems (FACTS) family using power electronics to improve transient stability in power system. For the SVC control, it is usually used a PI controller, although PI controller is simpler and cheaper but not suitable when power system is subjected to transient stability since power system become non-linear system. In order to overcome this problem, the PI controller combined with Fuzzy controller is designed. Two types of faults were considered for this study to examine the effect of the fuzzy-SVC controller on system transient stability, the proposed fault types are single line to ground fault and three lines to ground fault. The performance and behavior of the designed fuzzy controller compared with that of the conventional PI controller in term of terminal voltage, rotor angle, and transmission line active power. [ABSTRACT FROM AUTHOR]

Teixobactin, targeting lipid II, represents a new class of antibiotics with novel structures and has excellent activity against Gram-positive pathogens. We developed a new convergent method to synthesize a series of teixobactin analogues and explored structure–activity relationships. We obtained equipotent and simplified teixobactin analogues, replacing the l-allo-enduracididine with lysine, substituting oxygen to nitrogen on threonine, and adding a phenyl group on the d-phenylalanine. On the basis of the antibacterial activities that resulted from corresponding modifications of the d-phenylalanine, we propose a hydrophobic interaction between lipid II and the N-terminal of teixobactin analogues, which we map out with our analogue 35. Finally, a representative analogue from our series showed high efficiency in a mouse model of Streptococcus pneumoniae septicemia. [ABSTRACT FROM AUTHOR]

An efficient single-step approach toward the synthesis of 2-alkylquinolines is described. Through a Lewis acid mediated [3 3] annulation reaction between 3-ethoxycyclobutanones and aromatic amines, a variety of multisubstituted 2-alkylquinoline derivatives were prepared regioselectively at room temperature. [ABSTRACT FROM AUTHOR]

Abstract: Taking advantage of Fourier transform infrared spectrum and X-ray photoelectron spectroscopy, the researcher has conducted a contrastive research on the surface molecular structure of porous PVDF membrane before and after modification. Research results indicate that, though the C–F characteristic peak of the PVDF membrane still exists after modification, the peak is obviously flat, which indicates that the content of F atom decreases evidently; the results also indicate that hydroxyl characteristic peak is sharper, which indicates the content of O atom increases evidently. This proves that chemical binding force has been produced by chemical reactions on the surface of PVDF membrane during the modification. The coexistence of C–F functional group with C–OH one on the surface of PVDF membrane after modification proves that the surface features of the PVDF membrane have been successfully altered. Combination of Fourier transform infrared spectrum with X-ray photoelectron spectroscopy is proved an effective approach for analyzing the surface structure of the membrane. [Copyright &y& Elsevier]

Quorum sensing (QS) signals are widely used by bacterial pathogens to control biological functions and virulence in response to changes in cell population densities. Burkholderia cenocepacia employs a molecular mechanism in which the cis-2-dodecenoic acid (named Burkholderia diffusible signal factor, abbreviated as BDSF) QS system regulates N-acyl homoserine lactone (AHL) signal production and virulence by modulating intracellular levels of cyclic diguanosine monophosphate (c-di-GMP). Thus, inhibition of BDSF signaling may offer a non-antibiotic-based therapeutic strategy against BDSF-regulated bacterial infections. In this study, we report the synthesis of small molecule mimics of the BDSF signal and evaluate their ability to inhibit BDSF QS signaling in B. cenocepacia. A novel structural analogue of BDSF, 14- Me-C16:Δ² (cis-14-methylpentadec-2-enoic acid), was observed to inhibit BDSF production and impair BDSF-regulated phenotypes in B. cenocepacia, including motility, biofilm formation and virulence, while it did not inhibit the growth rate of this pathogen. 14-Me-C16:Δ² also reduced AHL signal production. Genetic and biochemical analyses showed that 14-Me-C16:Δ² inhibited the production of the BDSF and AHL signals by decreasing the expression of their synthaseencoding genes. Notably, 14-Me-C16:Δ² attenuated BDSF-regulated phenotypes in various Burkholderia species. These findings suggest that 14-Me-C16:Δ2 could potentially be developed as a new therapeutic agent against pathogenic Burkholderia species by interfering with their QS signaling. [ABSTRACT FROM AUTHOR]

The potentially hazardous iron-containing sludge from the Fenton process requires proper treatment and disposal, which often results in high treatment cost. In this study, a novel method for the reuse of Fenton sludge as an iron source for the synthesis of nickel ferrite particles (NiFe2O4) is proposed. Through a co-precipitation method followed by sintering at 800°C, magnetic NiFe2O4 particles were successfully synthesized, which was confirmed by powder X-ray diffraction (XRD), scanning electronic microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. The synthesized NiFe2O4 could be used as an efficient catalyst in the heterogeneous Fenton process. In phenol degradation with H2O2 or NiFe2O4 alone, the phenol removal efficiencies within the reaction time of 330 min were as low as 5.9% ± 0.1% and 13.5% ± 0.4%, respectively. However, in the presence of both NiFe2O4 and H2O2, phenol removal efficiency as high as 95% ± 3.4% could be achieved, indicating the excellent catalytic performance of NiFe2O4 in the heterogeneous Fenton process. Notably, a rapid electron exchange between NiII and FeIII ions in the NiFe2O4 structure could be beneficial for the Fenton reaction. In addition, the magnetic catalyst was relatively stable, highly active and recoverable, and has potential applications in the Fenton process for organic pollutant removal. [ABSTRACT FROM AUTHOR]

In this paper, spinel ferrite with high crystallinity and high saturation magnetization was successfully prepared from steel pickling sludge by adding iron source and precipitator in the hydrothermal condition. The obtained spinel ferrite was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometer (VSM), and Zeta potential methods and investigated as an adsorbent for removal of Pb2+ from aqueous solution. Batch experiments were performed by varying the pH values, contact time, temperature and initial metal concentration. The result of pH impact showed that the adsorption of Pb2+ was a pH dependent process, and the pH 5.8±0.2 was found to be the optimum condition. The achieved experimental data were analyzed with various kinetic and isotherm models. The kinetic studies revealed that Pb2+ adsorption onto spinel ferrite followed a pseudo-second order model, and the Langmuir isotherm model provided the perfect fit to the equilibrium experimental data. At different temperatures, the maximum Pb2+ adsorption capacities calculated from the Langmuir equation were in the range of 126.5–175.4 mg/g, which can be in competition with other adsorbents. The thermodynamic results showed that the spinel ferrite could spontaneously and endothermically adsorb Pb2+ from aqueous solution. The regeneration studies showed that spinel ferrite could be used five times (removal efficiency (%) >90%) by desorption with HNO3 reagent. [ABSTRACT FROM AUTHOR]

A novel method for preparation of polyethersulfone (PES) hybrid ultrafiltration (UF) membrane with sustainable antifouling property is developed. The highlight of this method is that the self-assembly of TiO2 nanoparticles around the pores of PES membranes was achieved during the formation of PES UF membrane via non-solvent induced phase separation (NIPS) process. The precursor (tetrabutyl titanate (TBT)) of TiO2 nanoparticles and triblock copolymer (Pluronic F127) were introduced to PES casting solution. The synchronous self-assembly of TiO2 nanoparticles around membrane pores and formation of PES polymeric membranes occurred during the NIPS process by controlling the hydrolysis and condensation of TBT. F127 plays an essential role in that its hydrophilic and hydrophobic segments have different affinity to the TiO2 nanoparticles and PES matrix respectively. TEM and SEM-EDX mapping confirm that TiO2 nanoparticles self-assemble around the pores of PES membranes. Water permeability of the resultant hybrid PES membranes was 4 times higher than that of neat PES membranes with a slight change of bovine serum albumin (BSA) rejection. The organic antifouling experiment, using BSA and humic acid (HA) as model foulants, manifest that the organic antifouling property of the PES hybrid membrane can be conspicuously enhanced. Importantly, the leaching of self-assembly TiO2 nanoparticles is restrained due to the interaction between the TiO2 nanoparticles and F127, which ensures a stable and sustainable antifouling activity of the membrane. [ABSTRACT FROM AUTHOR]

A combined zero valent iron (ZVI) and anaerobic-aerobic process was adopted for the treatment of 2,4-dinitrochlorobenzene (DNCB)-containing wastewater. The transformation pathway, reduction of acute toxicity and enhancement of biodegradability were investigated. After pretreatment by ZVI, DNCB in wastewater could be completely converted into 2,4-diaminochlorobenzene (DACB). The ratio of BOD5/COD increased from 0.005 ± 0.001 to 0.168 ± 0.007, while EC50,48hr (V/V) increased from 0.65% to 5.20%, indicating the enhancement of biodegradability and reduction of acute toxicity with the pretreatment by ZVI. DACB was further dechlorinated to m-phenylenediamine during the anaerobic process using methanol as electron donor, with EC50,48 hr increasing from 5.20% to 48.2%. After the subsequent anaerobic-aerobic process, m-phenylenediamine was degraded completely, with effluent COD of 67.5 ± 10.8 mg/L. This effluent of the subsequent anaerobic-aerobic process was not toxic to zebrafish. The combined ZVI and anaerobic-aerobic process offers bright prospects for the treatment of chlorinated nitroaromatic compound-containing wastewater. [ABSTRACT FROM AUTHOR]

Abstract: α-Al2O3 hollow fibers were prepared by a phase-inversion method combined with the reaction bonded aluminum oxide (RBAO) process. Next, γ-Al2O3 membranes, which were fabricated by a sol–gel process, were cast on the outer surface of the hollow fiber supports. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), nitrogen isothermal absorption measurements and gas permeability testing were used to characterize the supports and γ-Al2O3 membranes. The results showed that the mechanical strength of hollow fiber supports is better than that of non-RBAO hollow fiber, and their porosity and mean pore size were 50.1% and 0.88μm, respectively. SEM images of γ-Al2O3 membranes showed that the membranes were defect-free. The most concentrative pore diameter and the specific surface area of γ-Al2O3 membranes were about 4.5nm and 228.9m2/g, respectively. Gas permeability tests suggested that the γ-Al2O3 membranes possessed gas selectivity, and the separation factor for N2/Ar are 1.133 at 0.3MPa and 1.139 at 0.4MPa, respectively, which is slightly smaller than the value expected from the ideal Kundsen diffusion (α =1.194). [Copyright &y& Elsevier]

This paper explores the capability of the combined processes of extrusion molding and hydrothermal synthesis for the creation of porous granular single-phase zeolitic products which were prepared from coal fly ash. The key is to introduce the plasticizer of sodium carboxymethyl cellulose (CMC) in order to tailor the relative plasticity of the paste. Furthermore, CMC also acts as a kind of pore-forming agent. The crystalline phase, purity and morphologies of the semi-finished products and the products were characterized by XRD and SEM. Effects of material ration, concentration, crystallinity temperature and time were explored and optimal conditions were shown. The adsorption properties of the as-prepared sodalite pellets were evaluated by the removal of Pb2+. In comparison with commercial activated carbon particles, the as-prepared sodalite pellets exhibit good adsorption performances. [ABSTRACT FROM AUTHOR]