Pyrazine-based iron metal organic frameworks (Fe-MOFs) with modulated O-Fe-N coordination for enhanced hydroxyl radical generation in Fenton-like process.

Rational design of coordination environment of Fe-based metal-organic frameworks (Fe-MOFs) is still a challenge in achieving enhanced catalytic activity for Fenten-like advanced oxidation process. Here in, novel porous Fe-MOFs with modulated O-Fe-N coordination was developed by configurating amino terephthalic acid (H2ATA) and pyrazine-dicarboxylic acid (PzDC) (Fe-ATA/PzDC-7:3). PzDC ligands introduce pyridine-N sites to form O-Fe-N coordination with lower binding energy, which affect the local electronic environment of Fe-clusters in Fe-ATA, thus decreased its interfacial H2O2 activation barrier. O-Fe-N coordination also accelerate Fe(II)/Fe(III) cycling of Fe-clusters by triggering the reactive oxidant species mediated Fe(III) reduction. As such, Fe-ATA/PzDC-7:3/H2O2 system exhibited excellent degradation performance for typical antibiotic sulfamethoxazole (SMX), in which the steady-state concentration of hydroxyl radical (OH) was 1.6 times higher than that of unregulated Fe-ATA. Overall, this study highlights the role of O-Fe-N coordination and the electronic environment of Fe-clusters on regulating Fenton-like catalytic performance, and provides a platform for precise engineering of Fe-MOFs.

Enhanced 2-MIB degradation by UV-LED/chlorine process: reaction kinetics, wavelength dependence, influencing factors and degradation pathways.

The efficient removal of 2-Methylisoborneol (2-MIB), a typical odour component, in water treatment plants (WTPs), poses a great challenge to conventional water treatment technology due to its chemical stability. In this study, the combination of ultraviolet light-emitting diode (UV-LED) and chlorine (UV-LED/chlorine) was exploited for 2-MIB removal, and the role of ultraviolet (UV) wavelength was investigated systematically. The results showed that UV or chlorination alone did not degrade 2-MIB effectively, and the UV/chlorine process could degrade 2-MIB efficiently, following the pseudo-first-order kinetic model. The 275 nm UV exhibited higher 2-MIB degradation efficiency in this UV-LED/chlorine system than 254 nm UV, 265 nm UV and 285 nm UV due to the highest mole adsorption coefficient and quantum yield of chlorine in 275 nm UV. ·OH and ·Cl produced in the 275 nm UV/chlorine system played major roles in 2-MIB degradation. HCO3- and Natural organic matter (NOM), prevalent in water, consumed ·OH and ·Cl, thus inhibiting the 2-MIB degradation by UV-LED/chlorine. In addition, NOM and 2-MIB could form a photonic competition effect. The degradation of 2-MIB by UV-LED/chlorine was done mainly through dehydration and demethylation, and odorous intermediates, such as camphor, were produced. 2-MIB was degraded through the α bond fracture and six-membered ring opening to form saturated or unsaturated hydrocarbons and aldehydes. Four DBPs, chloroform (CF), trichloroacetaldehyde (TCE), trichloroacetone (TCP) and dichloroacetone (DCP), were mainly generated, and CF was the most significant by-product.

Enhanced arsenite removal from water using zirconium-ferrocene MOFs coupled with peroxymonosulfate:oxidation and multi-sites adsorption mechanism.

The efficient removal of arsenite (As(III)) poses a significant challenge to traditional water treatment technologies due to its high toxicity and mobility. In this work, multifunctional Zirconium-Ferrocene Metal Organic Framework (ZrFc-MOF) fabricated with redox-active 1,1-ferrocene dicarboxylic acid ligands and Zr4+ precursors were elaborated to achieve remarkably enhanced As(III) removal via activation by peroxymonosulfate (PMS). The adsorption affinity coefficient increased from 0.097 to 2.035 L mg-1 and the maximum adsorption capacity increased from 59.79 to 111.34 mg g-1 compared with that without PMS. Besides the conventional homogeneous PMS oxidation and the following adsorption through Zr-O clusters of ZrFc-MOFs, the enhanced As(III) removal synergistic combines the oxidation mechanism of As(III) by reactive oxygen species (•OH, SO4•-, O2•- and 1O2) formed in Ferrocene (Fc) activating PMS process with the simultaneous formed extra adsorption sites of Ferrocenium (Fc+). PMS also help ZrFc-MOF to avoid destruction in harsh alkaline condition, making the effluent in this advanced treatment meet the World Health Organization (WHO) threshold of 10 µg L-1 over a wide range of initial pH (2-11) with high selectivity and durability. These results indicate that this novel Fc-based MOFs activating PMS system has potential applicability for As(III) in oxidation and selectively capturing in the water environment.

Tuning the structure of cerium-based metal-organic frameworks for efficient removal of arsenic species: The role of organic ligands.

The ability of organic ligands to change the structure of metal-organic frameworks (MOFs) in nature and influence their adsorption efficiency for arsenic species is enormous. The current work was designed to investigate the adsorption performance of cerium-based MOFs with tunable structures through the use of organic ligands (Ce-MOF-66 and Ce-MOF-808) towards arsenic species from water. The structural features of Ce-MOF-66 and Ce-MOF-808 with varying crystallinity, morphology, particle size, and surface area are considerably altered by organic ligands tuning, resulting in clearly distinct arsenate (As (V)) and arsenite (As (III)) adsorption capabilities. The experimental results showed that the Langmuir adsorption capacities of As (V) by Ce-MOF-66 and Ce-MOF-808 reached 355.67 and 217.80 mg/g, respectively, while for As (III) were 5.52 and 402.10 mg/g for Ce-MOF-66 and Ce-MOF-808, respectively. Except for the impact of PO43- on As (V), co-existing ions had no significant influence on adsorption, illustrating the high selectivity. Furthermore, to understand the structure and adsorption mechanism, two adsorbents were characterized by powder X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, specific surface area, Fourier transform infrared and X-ray photoelectron spectroscopy, in which identified that unsaturated sites and ligand exchange were the main adsorption mechanisms of As (V) and As (III). Overall, this research presents a novel approach for developing high-performance Ce-derived MOFs adsorbents to capture arsenic species.

Maize leaf disease identification based on WG-MARNet.

In deep learning-based maize leaf disease detection, a maize disease identification method called Network based on wavelet threshold-guided bilateral filtering, multi-channel ResNet, and attenuation factor (WG-MARNet) is proposed. This method can solve the problems of noise, background interference, and low detection accuracy of maize leaf disease images. To begin, a processing layer called Wavelet threshold guided bilateral filtering (WT-GBF) based on the WG-MARNet model is employed to reduce image noise and perform high and low-frequency decomposition of the input image using WT-GBF. This increases the input image's resistance to environmental interference and feature extraction capability. Secondly, for the multiscale feature fusion technique, an average down-sampling and tiling method is employed to increase feature representation and limit the risk of overfitting. Then, on high and low-frequency multi-channel, an attenuation factor is introduced to optimize the performance instability during training of the deep network. Finally, when the convergence and accuracy are compared, PRelu and Adabound are used instead of the Relu activation function and the Adam optimizer. The experimental results revealed that our method's average recognition accuracy was 97.96%, and the detection time for a single image was 0.278 seconds. The average detection accuracy has been increased. The method lays the groundwork for the precise control of maize diseases in the field.

UiO-66(Zr)-derived t-zirconia with abundant lattice defect for remarkably enhanced arsenic removal.

Zirconium oxide (ZrO2) exhibits great potential in the remediation of arsenic-polluted water. In this study, tetragonal zirconium oxide (t-ZrO2) with high lattice defects was facilely fabricated by regulating the Zr-metal-organic framework (MOF) (UiO-66) with sodium acetate modulator and examined to adsorb arsenic from water. Benefitting from the synergistic effects of mesopores structure and lattice defect, t-ZrO2 exhibited ultrahigh adsorption capacity and faster kinetics towards both arsenate (As(V)) and arsenite (As(III)). The Langmuir adsorption capacity for As(V) and As(III) of 147.5 mg g-1 and 352.1 mg g-1 on t-ZrO2 in exothermic process, respectively, significantly outperforming reported counterparts in literature (generally ≤100 mg g-1). The faster adsorption kinetic of both As(III) and As(V) on t-ZrO2 is defined favorably by the pseudo-second-order model over a wide pH (3-11). Furthermore, arsenic is mainly captured by t-ZrO2 via forming Zr-O-As bonds through occupying coordinatively unsaturated zirconium atoms adsorption sites revealed by the X-ray photoelectron spectroscopy (XPS) spectrum and Fourier-transformed infrared (FTIR) spectra analysis. This study offers a new strategy for designing ultrahigh performance Zr-MOF-derived adsorbents for capturing arsenic.

Spontaneous bilateral renal pelvis rupture during CT in the absence of urinary tract obstruction: case report.

BACKGROUND: Atraumatic renal pelvis rupture without pre-existing renal or ureteric pathology is an uncommon event. It is reported in the setting of acute urinary tract obstruction, most often secondary to ureteric calculi. Typical symptoms include acute flank pain and nausea, mimicking pyelonephritis or other causes of acute abdomen. Spontaneous rupture occurring bilaterally without identifiable urinary tract obstruction is exceedingly rare, and has yet to be reported in current English literature. Possible contributing pathophysiological mechanisms can be postulated from reported cases of rupture with observed obstruction. CASE PRESENTATION: A 58-year-old woman undergoing multiphasic computed tomography (CT) for evaluation of asymptomatic microscopic haematuria developed on-table bilateral renal pelvis rupture seen only after contrast administration, on the delayed phase. There was no significant past medical history of note. The patient remained asymptomatic throughout and after the study, and was managed conservatively. Follow-up radiographical imaging over a month showed resolution of urinoma and no further contrast extravasation. No complications or recurrence was subsequently noted. CONCLUSIONS: Spontaneous rupture of the renal pelvis can be a rare complication of intravenous contrast administration even in cases without identifiable urinary tract obstruction, and it can occur bilaterally. Cases can uncommonly be asymptomatic but typical symptoms should prompt evaluation of the kidneys, particularly when they are not included in the initial study or no delayed phase is protocolled. Interval imaging for resolution of urinoma and contrast extravasation is clinically relevant to monitor for and avoid infective sequelae.

High selectivity and effectiveness for removal of tetracycline and its related drug resistance in food wastewater through schwertmannite/graphene oxide catalyzed photo-Fenton-like oxidation.

Selectively and effectively for removal of tetracycline (TC) and its related antibiotic resistance gene from food wastewater matrix with high-salt and high COD characteristics is highly desirable. In this work, novel schwertmannite/graphene oxide (SCH/GO) nanocomposites were synthesized through a facile oxidation-coprecipitation method. The SCH/GO nanocomposites were characterized by TEM, XRD, BET, PL, DRS, XPS and FTIR. In the presence of 1 mM H2O2, the SCH/GO catalyzed Fenton-like oxidation can thoroughly degrade TC under visible light irradiation, even under nature sunlight, whose second-order kinetic rate constant was about 15 times higher than that of pure SCH. SCH/GO was capable of highly selectively capturing and effectively degrading TC in the presence of similar concentration of Cl-, NO3-, SO42- and PO43- with that of food wastewater, even at organic matters concentration of 12.5 times than that of TC. At the same time, the removal of total organic carbon (TOC) and chemical oxygen demand (COD) in aforementioned food wastewater in SCH/GO+H2O2+Vis system reached 27.3 % and 34.5 % after 60 min, respectively. The inhibition zone experiments authenticated that the removal of drug resistance of bacteria by TC degradation intermediates can be achieved very well without producing secondary contamination in this system.

Adsorption behavior of arsenicals on MIL-101(Fe): The role of arsenic chemical structures.

Arsenic species are regarded as typical water pollutants due to their toxicity. The chemical structures of arsenic species greatly influence their migration and transformation in the environment. Metal-organic frameworks (MOFs) are used as reliable adsorbents to control arsenic contamination, so it is urgently needed to study the effect of chemical structure of arsenic species during adsorption process. The adsorption behaviors of arsenate (As(V)) and its organic forms such as roxarsone (ROX), p-arsanilic acid (p-ASA) and dimethyl arsenate (DMA) by MIL-101(Fe), a type of highly porosity iron-based MOFs in aqueous environment were detailed investigated. The adsorption kinetics of those arsenic species on MIL-101(Fe) is rapid followed with pseudo-second-order kinetic model. MIL-101(Fe) exhibits excellent adsorption capacities for As(V), ROX, p-ASA and DMA with maximum adsorption capacities of 232.98, 507.97, 379.65 and 158.94 mg g-1, respectively. The formed FeOAs inner-sphere coordination between arsenic species and the incomplete-coordinated cationic Fe in the MIL-101(Fe) cluster is the primary adsorption mechanism based on FTIR and XPS analysis. Substituent aromatic units in ROX and p-ASA strengthen the adsorption on MIL-101(Fe) through hydrogen bonds and π-π stacking interaction, resulting in higher adsorption capacities far beyond that of As(V) and DMA. The reusability of MIL-101(Fe) is limited by the strong FeOAs coordination. These results confirm MIL-101(Fe) a reliable adsorbent to control the aqueous arsenic species contamination and emphasize the significant role of the chemical structure of arsenic speciation on adsorption performances of MOFs.

Crack Monitoring Method for an FRP-Strengthened Steel Structure Based on an Antenna Sensor.

Fiber-reinforced polymer (FRP) has been increasingly applied to steel structures for structural strengthening or crack repair, given its high strength-to-weight ratio and high stiffness-to-weight ratio. Cracks in steel structures are the dominant hidden threats to structural safety. However, it is difficult to monitor structural cracks under FRP coverage and there is little related research. In this paper, a crack monitoring method for an FRP-strengthened steel structure deploying a microstrip antenna sensor is presented. A theoretical model of the dual-substrate antenna sensor with FRP is established and the sensitivity of crack monitoring is studied. The effects of the weak conductivity of carbon fiber reinforced polymers (CFRPs) on the performance of crack monitoring are analyzed via contrast experiments. The effects of FRP thickness on the performance of the antenna sensor are studied. The influence of structural strain on crack detection coupling is studied through strain-crack coupling experiments. The results indicate that the antenna sensor can detect cracks in steel structures covered by FRP (including CFRP). FRP thickness affects the antenna sensor's performance significantly, while the effects of strain can be ignored. The results provide a new approach for crack monitoring of FRP-strengthened steel structures with extensive application prospects.