The present study focused on evaluation of activated persulfate (PS) anion (S
2O
8
2−) oxidative degradation of benzene, toluene, ethylbenzene, and xylene (constituents of gasoline and known ...collectively as BTEX) contamination. The results indicated that BTEX were effectively oxidized by PS in aqueous and soil slurry systems at 20
°C. PS can be activated thermally, or chemically activated with Fe
2+ to form the sulfate radical (SO
4
−
) with a redox potential of 2.4
V. The degradation rate constants of BTEX were found to increase with increased persulfate concentrations. For two PS/BTEX molar ratios of 20/1 and 100/1 experiments, the observed aqueous phase BTEX degradation half-lives ranged from 3.0 to 23.1 days and 1.5 to 20.3 days in aqueous and soil slurry systems, respectively. In the interest of accelerating contaminant degradation, Fe
2+ and chelated Fe
2+ activated persulfate oxidations were investigated. For all iron activation experiments, BTEX and persulfate degradations appear to occur almost instantaneously and result in partial BTEX removals. It is speculated that the incomplete degradation reaction may be due to the cannibalization of SO
4
−
in the presence of excess Fe
2+. Furthermore, the effects of various chelating agents including, hydroxylpropyl-β-cyclodextrin (HPCD), ethylenediaminetetraacetic acid (EDTA), and citric acid (CA) on maintaining available Fe
2+ and activating PS for the degradation of benzene were studied. The results indicated that HPCD and EDTA may be less susceptible to chelated Fe
2+. In contrast, CA is a more suitable chelating agent in the iron activated persulfate system and with a PS/CA/Fe
2+/B molar ratio of 20/5/5/1 benzene can be completely degraded within a 70-min period.
The chemical functionalization of carbon nanotubes (CNTs) using sodium persulfate (SPS) oxidation was designed to improve their dispersion stability in water. The test results indicated that base ...activated SPS oxidation of CNTs (BSPS/CNTs) adds a significant amount of oxygen functional groups to the surface of CNTs. The BSPS/CNTs dispersion is dependent on a solution within the pH range of 5–12. Experimental results obtained by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy demonstrated that CNTs were successfully modified and the carboxylic functional groups (e.g., –COO–Na+ or –COO–H+) were created. The BSPS/CNTs, which carry negative charges, enhance the dispersion characteristics of CNTs. The BSPS/CNTs adsorption capacities of inorganic ions (e.g., copper ion) and organic compounds (e.g., benzene) were higher than those obtained by raw CNTs mainly due to enhanced CNTs dispersion. Furthermore, Langmuir and Freundlich adsorption models were applied to examine both raw CNTs and BSPS/CNTs adsorption behaviors. Copper and benzene sorption onto BSPS/CNTs fit the Freundlich isotherm model well, while raw CNTs adsorption did not fit any model. The findings of this study are of great significance for the base activated persulfate oxidation process, indicating that the functionalization of CNTs enhances CNTs dispersivity in water.
Purpose
To evaluate the effectiveness and safety of prophylactic intraoperative uterine artery embolization (UAE) performed immediately after fetal delivery during planned cesarean section or ...cesarean hysterectomy in patients with placenta accreta spectrum disorder or placenta previa.
Methods
A systematic search was conducted on Ovid MEDLINE and Embase, PubMed, Web of Science, and Cochrane databases. Studies were selected using the Population/Intervention/Comparison/Outcomes (PICO) strategy. The intraoperative blood loss and the rate of emergent peripartum hysterectomy (EPH) were the primary outcomes, whereas the length of hospital stay and volume of blood transfused were the secondary outcomes. A random-effects model was employed to pool each effect size. The cumulative values of the primary outcomes were calculated using the generic inverse variance method.
Results
Eleven retrospective cohort studies and five case series were included, recruiting 421 women who underwent prophylactic intraoperative UAE (UAE group) and 374 women who did not (control group). Compared with the control group, the UAE group had significantly reduced intraoperative blood loss (
p
= 0.020) during cesarean section or cesarean hysterectomy. Furthermore, the EPH rate was also significantly decreased (
p
= 0.020; cumulative rate: 19.65%), but not the length of hospital stay (
p
= 0.850) and volume of pRBC transfused (
p
= 0.140), after cesarean section in the UAE group. The incidence of major complications was low (3.33%), despite two patients with uterine necrosis.
Conclusion
The currently available data provides encouraging evidence that prophylactic intraoperative UAE may contribute to hemorrhage control and fertility preservation in women with abnormal placentation.
Registration
PROSPERO registration code: CRD42021230581.
https://clinicaltrials.gov/ct2/show/CRD42021230581
Level of Evidence
Level 2a, systematic review of retrospective cohort studies.
The reaction of V(PS3“)− (1) (PS3”=P(C6H3‐3‐Me3Si‐2‐S)33−) with H2O led to the formation of VIV(PS3“)(PS2”SH)− (2) (PS2“SH=P(C6H3‐3‐Me3Si‐2‐S)2(C6H3‐3‐Me3Si‐2‐SH)2−), indicating a hydrogen atom ...transfer from H2O to a bound thiolate in 1. Furthermore, the reaction of 1 with CH3OH gave the generation of complexes 2 and 3, VIV(PS3”)(PS2“SCH3)− (PS2”SCH3=P(C6H3‐3‐Me3Si‐2‐S)2(C6H3‐3‐Me3Si‐2‐SCH3)2−), implying that C−O and O−H bonds are cleaved by 1. Quantum mechanical calculations were performed to provide the mechanistic understanding for the reactivity of 1 with water. A key transition state with a lower kinetic barrier is identified. It involves an O−H bond cleavage by a dissociated thiyl radical with an interaction between an OH group and a neighboring bound sulfur donor. To our knowledge, the reactivity of 1 represents a new mode for water activation conducted through cooperation between a metal‐stabilized thiyl radical and a neighboring thiolato donor.
A metal‐bound thiyl radical is capable of activating H2O and CH3OH through the homolytic cleavage of O−H and C−O bonds, leading to the formation of thiol and methyl thioether. The system also represents a new type of transformation for water activation conducted through cooperation between a metal‐stabilized thiyl radical and a neighboring thiolato donor.
Site effect is considered a critical component affecting ground motions, and the shallow velocity structure is a primary factor for determining the site effect. The shallow velocity structure should ...be carefully evaluated to mitigate earthquake hazards. Thus, we use microtremor array measurements as well as the inversion of microtremor horizontal-to-vertical spectral ratios (MHVSRs) to investigate shallow S-wave velocity (Vs) profiles in Taiwan, which is one of the most seismically active areas of the world. On the basis of the diffuse field assumption, Vs profiles can be efficiently inverted. To reduce the nonuniqueness of MHVSR inversion, Vs profiles obtained using microtremor array measurements and from an engineering geological database were adopted as model constraints. Finally, this study included 3587 inverted MHVSR Vs profiles and 65 inverted Vs profiles from microtremor arrays. The results were used to create a detailed updated VS30 map of Taiwan and to map the depth contours of Z1.0; thus, the relationship between VS30 and Z1.0 was determined. We proposed a new parameter, HR, as a proxy for VS30, that is defined as a ratio of the average MHVSR across high- and low-frequency bands. This parameter was correlated to the predominant frequency without subjective selection. Moreover, we constructed a pseudo-three-dimensional shallow Vs model of Taiwan, which describes main shallow structural features and provides complete details for plain areas.
•More than 3500 Vs profiles in Taiwan are derived by adopting DFA theory.•Site parameters VS30, Z1.0, and the relationship of VS30 – Z1.0 for Taiwan are presented.•New predictive relationships between VS30, HR, and elevation are developed.•A pseudo-3D shallow Vs model of Taiwan was constructed up to a depth of approximately 1 km.
To explore the potential of field-effect transistors (FETs) based on monolayers (MLs) of the two-dimensional semiconducting channel (SC) for spintronics, the two most important issues are to ensure ...the formation of variable low-resistive tunnel ferromagnetic contacts (FCs) and to preserve intrinsic properties of the SC during fabrication. Large Schottky barriers lead to the formation of high resistive contacts, and methods adopted to control the barriers often alter the intrinsic properties of the SC. This work aims at addressing both issues in fully encapsulated ML WSe2 FETs using bilayer hexagonal boron nitride (h-BN) as a tunnel barrier at the FC/SC interface. We investigate the electrical transport in ML WSe2 FETs with the current-in-plane geometry that yields hole mobilities of ∼38.3 cm2 V–1 s–1 at 240 K and on/off ratios of the order of 107, limited by the contact regions. We have achieved an ultralow effective Schottky barrier (∼5.34 meV) with an encapsulated tunneling device as opposed to a nonencapsulated device in which the barrier heights are considerably higher. These observations provide an insight into the electrical behavior of the FC/h-BN/SC/h-BN heterostructures, and such control over the barrier heights opens up the possibilities for WSe2-based spintronic devices.
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•S-wave HVSR is dependent on the variation of earthquake hypocenters.•Deep events have larger S-wave HVSR than shallow events at low frequencies (0.2–3.0 Hz).•Different S-wave ...incidence angles into the Taipei Basin caused variable S-wave HVSR.•A depth-dependent empirical site-correction amplification function is established to improve ground motion prediction.
Techniques using horizontal-to-vertical spectral ratios (HVSR) have frequently been adopted in many studies, particularly of seismic site amplification. However, the influence of source location on the HVSR is not previously well-studied. This paper studies the variation of the S-wave HVSR in the Taipei Basin based on a variety of hypocenter locations. The earthquake records are classified into three categories, include depth, azimuth, and distance. We report the S-wave HVSR to have strong focal-depth-dependence, for which the HVSR of the deep events are larger than shallow events. Besides, the S-wave HVSR in the northern and northeastern parts of the basin also displays source azimuthal-dependence. However, there is no apparent difference in source distance-dependence. In contrast to the S-wave HVSR, the coda-wave HVSR all showed no apparent difference for various earthquake hypocenter locations. The synthetic modeling results support our idea that the cause of the variation of HVSR results for different earthquake focal depths is the different S-wave angles of incidence into the basin. Based on the dependency of the site amplification on the focal depth, a focal-depth-dependent empirical transfer function (ETF) was established. The focal-depth-dependent ETF was verified to improve the accuracy of the ground motion prediction by using the stochastic method in this study. We demonstrate that the source location effect, especially the focal depth, can significantly influence the S-wave HVSR and therefore needs to be taken into account in site response investigation.
This study investigated the potential usage of activated carbon (AC) as a permeable reactive barrier material for the adsorption of benzene contaminant. Sodium persulfate (SPS) or pyrite (FeS
2) ...activated SPS oxidation was used for the regeneration of spent AC. Results indicate that persulfate oxidation of AC caused a loss of electrons and a reduction in adsorptive capacity due to the formation of acidic functional groups on the AC. Concerning the reactants that can be used for oxidation of the benzene contaminants, SPS/FeS
2/AC, as oppose to SPS/AC, can achieve benzene destruction in both the aqueous and the sorbed phases. Furthermore, regeneration of benzene spent AC by SPS or SPS/FeS
2 revealed that SPS oxidation resulted primarily in desorption of benzene over direct oxidation of AC sorbed benzene. In contrast, the SPS/FeS
2 system achieved complete oxidation of desorbed benzene in the aqueous phase while also oxidizing sorbed benzene. Results of re-adsorption show that oxidative regeneration recovered around 70% of the AC adsorption sites and the remaining capacity was mostly occupied by the residual benzene on the AC. This study demonstrates that SPS or FeS
2 activated SPS oxidation is an effective alternative method for the regeneration of spent AC.
Phthalates are known endocrine disruptors that can have adverse effects on human hormonal balance and development. Phthalates are semi-volatile chemical compounds, thus they can continuously leach ...from phthalate-containing objects and pollute the environments such as offices or laboratories, where workers in these spaces can inhale potentially harmful amounts of phthalates. Identifying and removing phthalate-contaminated objects from these indoor environments can effectively eliminate exposure to these environmental hormones. However, as of now, it is highly impractical to perform a large-scale screening of phthalate-containing objects using conventional analytical techniques which are usually time- and labor-intensive. In this study, thermal desorption electrospray ionization mass spectrometry (TD-ESI/MS) combined with probe sampling was used to screen phthalates on all non-metallic objects in a mass spectrometry (MS) laboratory. Due to sample pre-treatment was unnecessary and there was no limitation of sampling on sample’s shape, size, and material, screening of phthalates on an object using this ambient mass spectrometric approach was completed within 30 s, which enable sufficient and high-throughput screening. Phthalate signals of di(2-ethylhexyl)phthalate (DEHP), diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP) were qualitatively detected on the surfaces of the filters of air conditioners and air purifiers and laboratory door, indicating there was a possibility of phthalates contamination in the studying area. Other screened objects in the laboratory included the ceiling, wall, floor, chairs, benches, pipes, mechanical vacuum pump tubes, and some personal belongings, all of which contained phthalates. Among them, floor and mechanical vacuum pump tubes contained high concentration of DEHP, DINP and DIDP, suggesting they were the main sources of phthalate contamination in the MS laboratory.
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We propose a methodology to implement horizontal-to-vertical Fourier spectral ratios (HVRs) evaluated from strong ground motion induced by earthquake (EHVRs) or ambient ground motion observed from ...microtremor (MHVRs) individually and simultaneously with the spatial correlation (SC) in a ground-motion prediction equation (GMPE) to improve the prediction accuracy of site effects. We illustrated the methodology by developing an EHVRs-SC-based model which supplements Vs30 and Z1.0 with the SC and EHVRs collected at strong motion stations, and a MHVRs-SC-based model that supplements Vs30 and Z1.0 with the SC and MHVRs observed from microtremors at sites which were collocated with strong motion stations. The standard deviation of the station-specific residuals can be reduced by up to 90% when the proposed models are used to predict site effects. In the proposed models, the spatial distribution of the predicted station terms for peak ground acceleration (PGA) from MHVRs at 3699 sites is consistent with that of the predicted station terms for PGA from EHVRs at 721 strong motion stations. Prediction accuracy for stations with inferred Vs30 is similar to that of stations with measured Vs30 with the proposed models. This study provides a methodology to simultaneously implement SC and EHVRs, or SC and MHVRs in a GMPE to improve the prediction accuracy of site effects for a target site with available EHVRs or MHVRs information.
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