Ketoprofen (KET) is a mostly used nonsteroidal anti-inflammatory drug that has been frequently detected in wastewater effluents and surface waters. In this study, we investigated the degradation of ...KET by sulfate radical (SO4-) based advanced oxidation processes (SR-AOPs) in aqueous solution. The degradation kinetics, mechanisms, and effects of natural water matrices on thermally activated persulfate (TAP) oxidation of KET were systematically investigated. Increasing the temperature and persulfate (PS) concentrations greatly enhanced the degradation of KET. KET degradation is pH-dependent with an optimum pH of 5.0. Reactions in the presence of radical quenchers revealed the dominant role of SO4- in oxidizing KET. Water matrix significantly influenced the degradation of KET. The common inorganic anions present in natural waters exhibited inhibitory effect on KET degradation, and the inhibition followed the order of Cl− > CO32− > HCO3− > NO3−; however, no significant inhibition of KET degradation was observed in the presence of Ca2+ and Mg2+ cations. The presence of natural organic matter (NOM) suppressed KET degradation, and the suppression increased as NOM concentration increase. Products identification and mineralization experiments revealed that KET and its degradation intermediates were finally transformed into CO2 and H2O. The results of this study indicated that applying SR-AOPs for the remediation of KET contaminated water matrix is technically possible.
•Effective oxidation of KET was achieved by heat-activated persulfate.•Natural water matrix significantly affected KET degradation.•SO4- plays dominant role in oxidizing KET.•KET and its intermediates were finally mineralized to CO2 and H2O in PS oxidation system.
The organic hybrids of thermoplastic polyurethane (TPU)/hindered phenol (AO-80) were prepared through melt blending, which was followed by hot and cold pressing procedure. The microstructure and ...dynamic mechanical properties of the hybrids were systematically investigated through SEM, DSC, XRD, FTIR, DMA and a tensile tester. The experimental results indicated that AO-80 was completely dissolved in the matrix. The glass transition of the soft segments of TPU was found to shift to higher temperature with the amount of AO-80 increasing, whereas the glass transition of the hard segments exhibited nearly no evident change, indicating that AO-80 was selectively located in the soft region of TPU and the formation of the strong intermolecular interactions (hydrogen bonding) between AO-80 and the soft region of TPU. With the increase of AO-80 in the hybrids, the tanδ peak gradually shifted to higher temperatures and the maximal tanδ value increased from 0.4 to 1.6. Meanwhile, the glass transition temperature ranges broadened and the TA value increased greatly with the more content of AO-80. Because of the decrease of the hard segments amount in the hybrids, the tensile stress of these hybrids decreased, but still maintained at a high level. The hybrids were expected to have potential applications as high performance damping materials combined with good mechanical properties.
•Adjustable robust optimization with decision-dependent polyhedral uncertainty sets.•Two-stage and multistage settings with both continuous and binary recourse.•Uncertainty set may be affected by ...binary recourse decisions in every stage.•Tractable approximations derived using a nonlinear decision rule approach.•Results highlight benefit from endogenous uncertainty and mixed-integer recourse.
Endogenous, i.e. decision-dependent, uncertainty has received increased interest in the stochastic programming community. In the robust optimization context, however, it has rarely been considered. This work addresses multistage robust mixed-integer optimization with decision-dependent uncertainty sets. The proposed framework allows us to consider both continuous and integer recourse, including recourse decisions that affect the uncertainty set. We derive a tractable reformulation of the problem by leveraging recent advances in the construction of nonlinear decision rules, and introduce discontinuous piecewise linear decision rules for continuous recourse. Computational experiments are performed to gain insights on the impact of endogenous uncertainty, the benefit of discrete recourse, and computational performance. Our results indicate that the level of conservatism in the solution can be significantly reduced if endogenous uncertainty and mixed-integer recourse are properly modeled.
Summary Objective The associations between air pollution and children’s respiratory health in the high pollution range have not yet been clearly characterized. We evaluated the effects of outdoor air ...pollution on respiratory morbidity in children selected from multiple sites in a heavy industrial province of northeastern China. Methods The study included 11,860 children aged 3–12 years, selected from 18 districts of 6 cities in Liaoning province, the participation rate is 89.9%. Informed consent and written responses to surveys about children’s historic and current health status, personal and household characteristics, and other information were obtained from parents. A two-stage regression approach was applied in data analyses. Results There were wide gradients for TSP (188–689 μg/m3 ), SO2 (14–140 μg/m3 and NO2 (29–94 μg/m3 ) across the 18 districts of 6 cities. The three air pollutants significantly increased the prevalence of persistent cough (21–28%), persistent phlegm (21–30%) and current asthma (39–56%) for each interquartile range increment (172 μg/m3 for TSP, 69 μg/m3 for SO2 , 30 μg/m3 for NO2 ), showing larger between-city effects than within-city. Rates of respiratory symptoms were significantly higher for children with younger age, atopy, respiratory disease in early age, family history of asthma or chronic bronchitis, and tobacco smoke exposure. Conclusion The high levels of outdoor air pollution in north China are positively associated with children’s respiratory symptoms, the associations with TSP appear to be stronger than SO2 and NO2.
Pore-filling N-isopropylacrylamide (NIPAAM) polymer hydrogels were successfully grafted onto track-etched polycarbonate (PC) membranes by plasma-induced graft copolymerization. The microstructure and ...morphology of the PC-g-PNIPAAM membranes were investigated by XPS, SEM, ATR-FTIR, TGA, and water flux experiments. The effective pore sizes were regulated by the volume change of the cross-linked PNIPAAM hydrogels in the temperature range around its lower critical solution temperature (LCST). The PC-g-PNIPAAM membranes demonstrated a fast and reversible valve switching mechanism in a small temperature range. The on−off water flux ratio became more significant with the increase of the monomer concentration. Contact angle results showed that the thermal-responsive gating characteristics of PC-g-PNIPAAM membranes were mainly dependent on the pore size change.
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As one of the most toxic heavy metal ions, lead pollution has become an urgent problem. Here, a cubic crystal nanoparticle (Prussian blue analogue, PBA), referred to as potassium ...manganese ferrocyanide (KMFC) was synthesized and used as a highly-effective sorbent for removing Pb(II) from aqueous solution. KMFC is a mesoporous material that has excellent ion exchange properties, which was confirmed by a series of characterizations. This paper investigated the adsorptive attributes of KMFC for lead ions in aqueous solution. The influences of temperature, contact time and pH on adsorption were studied in batch experiments. The KMFC possessed a robust adsorption capacity for resident lead ions in aqueous solution, which attained 1075.27 mg g−1 at room temperature (25 °C), based on the Langmuir model, which was far higher than any previously reported values. The adsorption process was well fitted to a pseudo-second-order kinetic model, as well as Langmuir and Temkin isotherm models, and was endothermic and spontaneous on the basis of thermodynamic analysis. The adsorption of Pb(II) on the surface of KMFC started with electrostatic attraction, due to the electronegativity of KMFC. Further, ion exchange was the dominant mechanism in this adsorption process, which was confirmed by FTIR, XPS, and other supplementary experiments. The good chemisorption (K+ exchange) properties of KMFC suggested that it likely has excellent prospects in applications for heavy metal ions adsorption. This study not only provided a new perspective for the design and development of heavy metal sorbents but provided a deep insight into the mechanism of adsorption of heavy metal ions by PBA.
The aryl organophosphate flame retardant triphenyl phosphate (TPhP) has been frequently detected in environment and biota, and the potential risks of TPhP to aquatic organisms have also been ...demonstrated. The degradation of TPhP by CoFe2O4 activated peroxymonosulfate (PMS) was studied in this work. At initial pH of 7.0, 10 μM TPhP could be removed by 99.5% with 0.25 g/L CoFe2O4 and 0.5 mM PMS after 6 min oxidation, indicating the excellent performance of CoFe2O4 activated PMS process on the treatment of TPhP. The influence of PMS and CoFe2O4 dosage, initial pH, humic acid (HA), and anions (Cl−, NO3−, and HCO3−) on TPhP degradation were investigated systematically. Results showed that the degradation of TPhP was enhanced with increasing PMS concentrations from 0.1 to 1 mM, while it reduced as CoFe2O4 dosage increased. TPhP degradation efficiencies depended on solution pH with neutral pH showing the optimum degradation conditions. Recycling experiment indicated that the CoFe2O4 nanoparticles (NPs) possessed high potential for reusability. The radical identification experiments were performed and SO4•− was confirmed as the dominant radicals in TPhP degradation, and activation mechanism of PMS by CoFe2O4 NPs was hence explained. Humic acids (HA) (2–20 mg/L) as the representative organic natural matter existing in environment inhibited TPhP removal. Anions including Cl−, NO3−, and HCO3– all reduced TPhP degradation. In addition, TPhP degradation products were identified by liquid chromatography-mass spectrometry, and the degradation pathways of TPhP were proposed accordingly.
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•Inorganic ions and humic acid inhibited TPhP degradation.•Better TPhP removal was achieved at neutral pH•CoFe2O4-activated PMS oxidation of TPhP showed low mineralization.
X‐ray free‐electron lasers (FELs) have opened unprecedented possibilities to study the structure and dynamics of matter at an atomic level and ultra‐fast timescale. Many of the techniques routinely ...used at storage ring facilities are being adapted for experiments conducted at FELs. In order to take full advantage of these new sources several challenges have to be overcome. They are related to the very different source characteristics and its resulting impact on sample delivery, X‐ray optics, X‐ray detection and data acquisition. Here it is described how photon‐in photon‐out hard X‐ray spectroscopy techniques can be applied to study the electronic structure and its dynamics of transition metal systems with ultra‐bright and ultra‐short FEL X‐ray pulses. In particular, some of the experimental details that are different compared with synchrotron‐based setups are discussed and illustrated by recent measurements performed at the Linac Coherent Light Source.
Measurements of the soft x-ray, self-seeding spectrum at the Linac Coherent Light Source (LCLS) free-electron laser generally display a pedestal-like distribution around the central seeded ...wavelength. This pedestal limits the spectral purity and can negatively affect some user applications not employing a post-undulator monochromator. In this paper, we investigate the detailed experimental characteristics of both the amplified seed and its accompanying pedestal using data from a number of separate LCLS shifts over the 2015-2018 time period. We find that the amplified seed shows excellent wavelength stability and an exponential growth rate whose dependence upon energy detuning is consistent with theory. The pedestal’s spectral distribution and integrated strength vary strongly shot by shot, independent of electron beam energy jitter. Its shot-averaged strength relative to that of the seed grows at least linearly withzand can approach values of 15% or more. The pedestal is comprised of two separate components: (1) normal self-amplified spontaneous emission (SASE) whose total strength is nominally insensitive to energy detuning and laser heater (LH) strength; (2) sideband-like emission whose strength positively correlates with that of the amplified seed and negatively with energy detuning and LH strength. We believe this latter, non-SASE component arises from comparatively long wavelength (i.e.,λ∼0.3–3μm) amplitude and phase modulations of the main seeded radiation line. Its shot to shot variability and LH sensitivity suggests an origin connected to growth of the longitudinal microbunching instability on the electron beam.
A robust digitally assisted self-calibration technique is presented to improve the input-referred second-order-intermodulation intercept point (IIP 2 ) of direct-conversion receivers. The low-power, ...low-noise 1.8-GHz CMOS receiver prototype relies on digital signal processing to improve analog/RF performance with only a minimum hardware overhead and with no performance penalties on the RF front end and analog baseband. The RF front end achieves an IIP 2 better than 60 dBm without external filters between the LNA and downconversion mixers, has a conversion gain of 38.5 dB, a low DSB noise figure of 2.6 dB, and an IIP 3 of -17.6 dBm. It consumes 15 mA from a 1.5-V supply, and occupies 1.56 mm 2 on a 0.13-μm CMOS process.
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