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Recycling high-grade rare earth polishing powder waste (REPPW) is crucial for protecting the environment and sustainable utilization of rare earth resources. Leaching REPPW in the eco-friendly H 2 O 2 -H 2 SO 4 suffers from the lack of understanding of the leaching mechanism. Here, the leaching mechanism was investigated under the optimal leaching conditions, i.e., T = 353 K, L/S ratio = 40 mL/g, H 2 SO 4 concentration = 4 mol/L and initial H 2 O 2 concentration = 0.8 mol/L, by which leaching efficiency of Ce and La reached 99.3% and 99.1%, respectively. Furthermore, pseudo steady state kinetic analysis suggested a five-step leaching mechanism involving CeO 2 hydroxylation, H 2 O 2 -CeO 2 coordination, ≡ Ce III − H 2 O 2 deprotonation, ≡ Ce IV − H O 2 − reduction and ≡ Ce III − H O 2 ∗ protonation, which was verified by the agreement between experimental data and the proposed reaction model. This work proposes a leaching mechanism of REPPW and would help develop an effective and sustainable recycling process for rare earth secondary resources. [Display omitted] • Ce and La were effectively leached from REPPW using the H 2 O 2 -H 2 SO 4 system, resulting in leaching efficiencies of 99.3% and 99.1% for Ce and La, respectively. • A reasonable leaching cycle of CeO 2 in the H 2 O 2 -H 2 SO 4 system was verified by a pseudo steady state analysis. • A clean and efficient method for recycling rare earth solid waste resources [ABSTRACT FROM AUTHOR]

• The unexpected fracture of tube-to-tubesheet joints of a circulating oil steam generator is studied. • Caustic stress corrosion cracking is the root cause of the failure. • Proposals are given about material selection, manufacture and water quality assurance of the circulating oil steam generator. Tube-to-tubesheet joints are generally considered as one of the vulnerable part of heat exchangers, as they are sensitive to stress corrosion owing to residual stress generated during manufacture processes. As a result, it is crucial to carry out failure analysis on tube-to-tubesheet joints to ensure the safety of heat exchanger operations. The unexpected fracture of tube-to-tubesheet joints of a circulating oil steam generator in a petrochemical plant is studied. In order to find out the cause of the failure, the failed tube is investigated by visual inspection, base metal inspection and fracture morphologies observation. The results show that due to insufficient expansion of the tube, a gap is formed between the tube and tubesheet, which concentrates the alkali lye and chloride deposits, leading to the formation of caustic stress corrosion cracks in the outer wall of the failed tube before fracture, and the cracks rapidly propagate under tensile stress resulting in the failure. Finally, proposals are given about material selection, manufacture and water quality assurance of the circulating oil steam generator. [ABSTRACT FROM AUTHOR]

[Display omitted] • An Efficient and value-added flowsheet for recycling rare earth polishing powder waste is proposed. • Coordination enhanced led to high leaching ratios in mild acidic conditions. • The coordination stability constant of Ce3+-ascorbic acid was determined. • High-purity mesoporous Ce-La oxide cube was synthesized by a facile chemical precipitation method. Efficient and environmental-friendly recycling of rare earth polishing powder waste (REPPW) is imperative not only to ecological well-being but also to sustainability of critical rare earth resources. However, the low leaching efficiency of rare earth elements in mild acidic conditions and complicated synthesis procedure of high-end products hindered industrial recycling of REPPW. Herein, an ascorbic acid-H 2 SO 4 system with mild conditions, i.e., ascorbic acid concentration = 0.042 mol/dm3, H 2 SO 4 concentration = 1 mol/dm3, liquid to solid ratio = 20 cm3/g and temperature = 353 K, is proposed for leaching REPPW, in which the leaching ratios of Ce and La reached 96.79 % and 93.81 %, respectively. The coordination stability constants of Ce3+-ascorbic acid, i.e., β 1 = 106.88 and β 2 = 1013.03, were determined by pH-potentiometry, which revealed that the enhanced Ce3+ dissolution in this mild leaching system was attributed to Ce3+-ascorbic acid coordination. Subsequently, a high-purity, mesoporous Ce-La oxide cube was synthesized from the leaching solution by a facile chemical precipitation method at atmospheric pressure and temperature. The product had a composition of 78.07 wt% CeO 2 and 21.93 wt% La 2 O 3 , and its average pore diameter was 7.30 nm. Its reducibility was 1.52 times higher than the theoretical value, suggesting a high potential for catalyzing redox reactions. This work proposes an efficient and value-added process for recycling REPPW, which helps to enlighten the sustainable utilization of secondary rare earth resources. [ABSTRACT FROM AUTHOR]

Due to the misuse of various antibiotics, the problem of bacterial resistance has become more serious worldwide, and the associated diseases have significantly increased the medical burden of society. Antimicrobial photodynamic therapy (PDT) has received widespread attention because of its safety, efficiency, and facile implementation. Here, we report an oxygen-supply antibacterial agent (Ce6@CS/CP), which could enhance the efficacy of antibacterial PDT via photosynthesis of O 2. Ce6@CS/CP displayed a robust interaction with bacteria, hence facilitating the delivery efficiency of Ce6. In vitro experiments demonstrated that the photodynamic bactericidal potency of Ce6@CS/CP was remarkably greater than that of free Ce6. Furthermore, Ce6@CS/CP also exhibited superior significant antibiofilm activity to free Ce6. As a live oxygen-supply antibacterial agent, Ce6@CS/CP possesses excellent bacteria delivery ability of Ce6 and could enhance the potency of antibacterial PDT by photosynthesis, offering a new strategy for fighting against drug-resistant bacteria. [Display omitted] • Chitosan-coated chloroplast with sufficient photosynthesis activity would act as an oxygen-producing carrier for photosensitizer. • The constructed live oxygen-supply antibacterial agent (Ce6@CS/CP) facilitates the bacterial interaction and delivery efficiency of Ce6. • Its photodynamic antibacterial potency is remarkably greater than free Ce6. • The drug-resistant bacterial biofilm could be effectively ablated by Ce6@CS/CP plus light irradiation. [ABSTRACT FROM AUTHOR]

[Display omitted] • SIF and NDVI datasets had large differences on Yun-Gui Plateau and northwestern China. • Drought propagation time based on NDVI is larger than that based on SIF. • Drought had a similar impact degree in SIF and NDVI. • Both SIF and NDVI showed similar performance when monitoring crop yield. An increase in global warming has resulted in a global increase in meteorological droughts. As droughts play a key factor regulating vegetation growth, they inevitably have social and economic effects. Understanding vegetation dynamics and its response to climate change is therefor highly important to reveal the behavior mechanism of terrestrial ecosystems and to guide environmental management. In this investigation, Solar-induced Chlorophyll Fluorescence (SIF) and the Normalized Difference Vegetation Index (NDVI) were applied as vegetation indicators to describe vegetation dynamics and meteorological drought was described using the standardized precipitation evapotranspiration index (SPEI). Bias correction of precipitation and crop yield data of major crop producing areas was also used. By employing correlation coefficient of the maximum absolute value, a drought impact degree and propagation time to vegetation were defined. Dimensions of SIF and NDVI were unified by normalization. Results indicated that: (1) SIF and NDVI generally had a high level of consistency over China, and NDVI had a higher normalized value distribution level than SIF for different vegetation types. (2) Drought generally had a negative impact on vegetation in northern China and a positive impact in southern China. (3) Drought propagation time based on NDVI was larger than that based on SIF. (4) SIF had some advantages when monitoring crop yields among different crop producing areas. Results from this investigation will enable a greater understanding of SIF and NDVI for their application to monitor droughts and crop yield. [ABSTRACT FROM AUTHOR]

The effects of the formaldehyde to phenol molar ratio (F/P) on the combustion behavior of phenolic foams were discussed. Phenolic foams have been prepared with different F/P of resole resin. FTIR, TG and SEM were used for assessment of the molecular structure, thermal stability, and cell structure of phenolic foam (PF) analysis, respectively. It was found that the higher the F/P, the more inflammables content in the PF that promoted the formation of the char layer, and the higher the LOI of PF. Although the closed cell proportion of PF decreases with the increase of F/P, the effect of the open and closed cell proportion on the LOI of PF was much lower than that of the content of inflammables when there was little difference in cell size. It is worth noting that the smoldering time and smoldering velocity of PF also increased with the increase of F/P. When F/P exceeds 2.3, a large number of open-cell structures appear in the PF, resulting in a phenomenon of smoldering to burnout. The relationship between smoldering velocity and F/P can be calculated by an Arrhenius type expression. Arrhenius-type expression calculation showed that when the F/P reached 2.3, the smoldering velocity increased sharply, reaching a maximum of 0.193 mm/s. • The factors affecting the combustion behavior of phenolic foam (PF) were revealed. • The effect of closed cell proportion on LOI of PF is lower than that of the content of inflammables. • The higher the formaldehyde to phenol molar ratio (F/P), the greater the smoldering time and velocity. • The relationship between smoldering velocity and F/P can be calculated by an Arrhenius type expression. [ABSTRACT FROM AUTHOR]

• Proposed three maintenance polices for parallel systems with two failure modes. • Analyzed and compared the cost-effectiveness of the maintenance polices. • Developed simulation model for complex scenarios. • Useful insights are gained based on the numerical analysis. The parallel structure in the reliability engineering is widely used in many industrial systems such as power generation systems, pump systems, production systems and computing systems. Designing the optimal maintenance policies for these parallel systems can minimize the operation cost while achieving a satisfying system availability. Previous studies have studied various maintenance optimization for parallel systems. However, little research has considered the multiple failure modes that widely exist in many real industrial systems. This research considers a parallel system that consists of heterogeneous components subject to two types of competing failures: a one-stage catastrophic failure and a two-stage delay-time failure. Inspections are conducted periodically to identify the state of each component. Three maintenance policies are proposed in this research. To find the optimal inspection interval, we analyze the renewal process of the system to minimize the long-term expected cost per unit time. A simulation procedure is proposed to evaluate the long-term expected cost per unit time. Numerical experiments are carried out to illustrate the applications of the proposed maintenance policies. The discussion provides useful insights on choosing the best policy under different system performance requirements. [ABSTRACT FROM AUTHOR]

Wound dressing diligently facilitate healing by fostering hemostasis, immunoregulation, the angiogenesis, and collagen deposition. Our methodology entails fabricating chitosan-taurine nanoparticles (CS-Tau) through an ionic gelation method. The morphology of CS-Tau was observed utilizing Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Dynamic Light Scattering (DLS). The nanoparticles are subsequently incorporated into carboxymethyl chitosan hydrogels for crosslinking by EDC-NHS, yielding hydrogel dressings (CMCS-CS-Tau) designed to extend the duration of taurine release. In vitro investigations confirmed that these innovative compound dressings displayed superior biodegradation, biocompatibility, cytocompatibility, and non-toxicity, in addition to possessing anti-inflammatory properties, and stimulating the proliferation and mobility of human umbilical vein endothelial cells (HUVECs). Experiments conducted on mice models with full-thickness skin removal demonstrated that CMCS-CS-Tau efficaciously aided in wound healing by spurring angiogenesis, and encouraging collagen deposition. CMCS-CS-Tau can also minimize inflammation and promote collagen deposition in chronic diabetic wound. Hence, CMCS-CS-Tau promotes both acute and chronic diabetic wound healing. Furthermore, the sustained release mechanism of CMCS-CS-Tau on taurine reveals promising potential for extending its clinical utility in relation to various biological effects of taurine. A schematic illustration and the mechanism of CMCS-CS-Tau facilitate acute and chronic diabetic wound healing [Display omitted] • This research fuses taurine with chitosan into nanoparticles, fostering sustained release of taurine; • CMCS-CS-Tau facilitates its anti-inflammatory function, contributing to the healing process; • CMCS-CS-Tau reveals promising potential for extending its clinical utility. [ABSTRACT FROM AUTHOR]

[Display omitted] • Phosphated lignocellulose nanofibrils were combined with MXene and gelatin; • The aerogel exhibited excellent fire retardancy with fire-warning performance; • Performance of electromagnetic interference shielding also achieved highly. Lightweight electromagnetic interference (EMI) shielding material with environment-friendly and high fire-safe has imperative practical significance in civil electronic devices. Herein, a distinct strategy was proposed to integrate phosphated lignocellulose nanofibrils (PLCNFs), gelatin, and MXene into a hybrid composite aerogel (PGM aerogel) with ultralight weight and high porosity. Due to the synergistic flame retardant effect of the ternary mixture, PGM aerogel exhibited excellent fire retardancy, whose dramatical changes in electronic resistance was supposed to achieve a short fire-warning signal (∼1 s). The limiting oxygen index (LOI) was as high as 32 % and the peak heat release rate (PHRR) was relatively as low as 30.1 W/g. Furthermore, the aerogel also displayed great specific EMI shielding effectiveness (SE) of SSE/t (14230 dB cm2 g−1) at 8.2 GHz. Therefore, this PGM aerogel can be a potential candidate in both EMI shielding and fire-warning fields. [ABSTRACT FROM AUTHOR]

• A mitigating crosstalk method is proposed by simultaneously propagating a probe beam with a data beam when the multiplexed vortex beam are propagated over a atmosphere turbulence (AT) free space. • A conjugated crosstalk is achieved by the probe beam during the square-law mixture in a photoelectric detector. • The conjugated crosstalk phase can effectively synthesize the crosstalk of data beam induced by AT. • A proof of concept is built to investigate the crosstalk, bit error rate, constellation plot, stability of system, etc. for verifying the feasibility of the proposed concept in practice. To overcome the upcoming famine of channel capacity driven by explosive increases of new applications, optical orbital angular momentum (OAM) carried by a vortex beam has been considered to be a promising candidate for space-division multiplexing (SDM) in a novel physics domain. However, owing to the inescapable disturbance induced by atmosphere turbulence (AT), the performance of OAM-based free-space optical communication (FSOC) is seriously restrained, which can be ascribed to the crosstalk among different OAM modes induced by the distorted helical phase. For promoting the development of OAM-based FSOC, a synthesizing-crosstalk method is proposed for mitigating the AT by coaxially propagating an OAM-probe beam (OPB), wherein the OAM mode of the extra OPB is identical to the OAM mode of the propagated OAM-data beam (ODB). The corresponding theory analysis of the proposed method demonstrates that the conjugated distortion of the crosstalk can be generated by a hybrid of the OPB and the ODB in a photoelectric receiver/detector (PD/PR). The generated conjugate distortion of the OPB can effectively counteract the crosstalk of ODB induced by the turbulence. To verify the feasibility of the proposed scheme, an experimental setup is built. The measured results demonstrate that the bit error rate (BER) and constellation plot (CP) of the employed two OAM channels can be significantly improved under different atmosphere turbulence (AT) by utilizing the proposed scheme. A continuous 30 min-long-BER-testing results depict that the proposed concept can stably work well. The proposed concept can be also suitable for multiplexing other OAM modes as well as the employed two OAM channels. Besides, with the increase of data speed, the proposed scheme can also effectively mitigate the crosstalk and improving the system performance. Consequently, the proposed concept is valid and feasible both in theory and practice, which can be used for compensating the distorted helical phase and improving the system performance of an OAM-based FSOC in the future. [ABSTRACT FROM AUTHOR]

Crystalline porous covalent frameworks (COFs) have been considered as a platform for uranium extraction from seawater and nuclear waste. However, the role of rigid skeleton and atomically precise structures of COFs is often ignored in the design of defined binding configuration. Here, a COF with an optimized relative position of two bidentate ligands realizes full potential in uranium extraction. Compared with the para-chelating groups, the optimized ortho-chelating groups with oriented adjacent phenolic hydroxyl groups on the rigid skeleton endow an additional uranyl binding site, thereby increasing the total number of binding sites up to 150%. Experimental and theoretical results indicate that the uranyl capture is greatly improved via the energetically favored multi-site configuration and the adsorption capacity reaches up to 640 mg g−1, which exceeds that of most reported COF-based adsorbents with chemical coordination mechanism in uranium aqueous solution. This ligand engineering strategy can efficiently advance the fundamental understanding of designing the sorbent systems for extraction and remediation technology. [Display omitted] • The COFs were used as bio-inspired folded scaffold structure to regulate the configuration of chelating groups. • The COFs with different configurations were synthesized by introducing isomeric building units. • The optimized configuration provides more UO 2 2+ binding sites without redundant chelating groups introduced. • 2,3-DhaTat-COF achieved high uranium adsorption capacity of 640 mg∙g−1 and short adsorption equilibrium time. • Selectivity for capturing uranium from nuclear wastewater and seawater. [ABSTRACT FROM AUTHOR]

Whether the resistive switching (RS) behavior can be triggered in macroscopic level or not is still decade-long controversy because the mobile ion migration is extremely limited in such level. To demonstrate this point, ultra-long hybrid organic-inorganic perovskite halide (HOIPH; CH 3 NH 3 PbI x Cl 3-x) single nanowire is deliberately synthesized by three-steps: heating, vacuuming, and exposing to air atmosphere. A typical bipolar RS behavior with resistance ON/OFF ratio of >105 is observed in the HOIPH-based memristor. The MAPbI 3 -type perovskite crystal, I−, PbI 3 − and MA+ surrounded by the transition phase crystal to form the ultra-long HOIPH nanowire is verified by the HR-TEM observation. The observed RS memory behavior is ascribed to the ion long-distance migration in the transition phase. The Joule heat-based sublimation leads to the HOIPH structure collapse and then causes the RS invalidation. We disclose a novel RS memory mechanism that involves the ion abnormal migration in transition phase CH 3 NH 3 PbI x Cl 3-x ultralong single nanowire. This work provides a deep comprehension on the HOIPH system in various nanoscale electronic devices. [Display omitted] • CH 3 NH 3 PbI x Cl 3- x single ultralong nanowire is synthesized using three steps. • Bipolar digital-type RS memory behaviors are observed in ultralong nanowires. • Transitional phase-based PbI 3 − migration dynamic is verified by HR-TEM observations. [ABSTRACT FROM AUTHOR]

Purpose: Preoperative prediction of overt hepatic encephalopathy (OHE) should be performed in patients with variceal bleeding treated using the transjugular intrahepatic portosystemic shunt (TIPS) procedure. A reliable prediction tool is therefore required.Method: Patients with cirrhosis-related variceal bleeding treated using the TIPS procedure were screened at two hospitals. Patients classified as Child-Pugh Class B were identified. The least absolute shrinkage and selection operator method and the backward stepwise selection method were used to screen the clinical and radiological characteristics of participants. Then, models were constructed accordingly to predict OHE. Area under the receiver operating characteristic curves, calibration curves, and decision curves were performed to discover the optimal model. Finally, whether clinical factors influenced the performance of our optimal model was tested.Results: A total of 191 patients were included (training cohort: 127 cases; validation cohort: 64 cases). Three novel radiological independent risk factors were found. The combined model outperformed the models containing clinical factors or radiological characteristics alone. The areas under the curve for the training and validation cohorts were 0.901 and 0.903, respectively, with satisfactory calibration and decision curves. The Model for End-Stage Liver Disease score, serum sodium, albumin, total bilirubin, and age exhibited limited influence on the performance of the combined model.Conclusions: These radiological characteristics are also independent risk factors for post-TIPS OHE. Combining clinical factors and radiological characteristics was an effective means of predicting OHE. This study's model could be used for preoperative selection of appropriate patients before the TIPS procedure is performed. [ABSTRACT FROM AUTHOR]

Due to the mutual orthogonality among different orbital angular momentums (OAMs), vortex beams (VB) carrying OAMs have been widely employed in the form of encoding/decoding or mode-/space-division multiplexing (M/SDM) for further promoting the channel capacity and spectrum effectiveness in a free-space optical communication (FSOC) and an optical fiber communication (OFC), respectively. For improving the propagation distance and loss in the OFC, a propagation concept of VB is proposed by multiplexing OAM-mode groups (OMGs) over a homemade ring-core fiber (RCF). The step-index RCF is proposed and fabricated in our Lab for supporting OMGs propagation and multiplexing with lower loss, which can support 6 OMGs. A proof-of-concept experimental setup is also proposed and performed for verifying the feasibility and validity of the proposed concept, where 16-quadrature amplitude modulation (16-QAM) signal is employed. The detected intensity profiles and interference graphs demonstrate that 5 OMGs can be successfully propagated over the RCF and received at the receiver. For evaluating the performance of the proposed scheme, bit-error rates (BER) and constellation graph (CG) are utilized. The measured BERs and CGs show that the system performance degrades as the order of OMGs or data rate increases and the influence of carrier wavelength on the performance of system is relatively weak in C band. In addition, the measured crosstalk inter-OMGs is much lower than the crosstalk intra-OMGs. The aforementioned results demonstrate that the proposed approach is correct and reliable and can enhance propagation distance and reduce the loss for a long-haul OFC. [ABSTRACT FROM AUTHOR]

[Display omitted] • Observed the phase transition of perovskite driven by SnO 2 under UV light. • In-situ synthesis of PSS-Pb layer at the interface of SnO 2 /perovskite. • The PSS-Pb layer was used as barrier to inhibit phase-transition of perovskite. • The PSS-Pb layer stabilize the interface and passivate interface defects. • Obtained a high open-circuit voltage of 1.19 V and an improved efficiency of 22.26% The harmonious coordination between the perovskite and the charge transport layer is the prerequisite for the high efficiency and stability of perovskite solar cells (PSCs). The excellent photoelectric and solution processable SnO 2 electron transport material opens the most commercial potential of planar PSCs. However, SnO 2 has rich surface activity and photocatalytic properties, which will deteriorate perovskite after absorbing UV light and seriously affect the stability and efficiency of PSCs. Here, the interface barrier strategy is introduced to insert an anchored-then-rinsed lead polystyrene sulfonate (ARPSS-Pb) polyionic layer between SnO 2 and perovskite via in-situ synthesis method to construct a new stable interface, which can effectively block the phase transition of perovskite driven by photocatalytic SnO 2. In addition, ARPSS-Pb also has the functions of passivating interfacial defects, relaxing interfacial stress and guiding crystallization of perovskite. PSCs based on ARPSS-Pb achieved a power conversion efficiency (PCE) of 22.26%, much higher than 19.60% of the control devices. More importantly, after 1000 h of storage under continuous humidity conditions, up to 96.32% of the initial PCE is maintained. A high open circuit voltage (V OC) as high as 1.190 V has been obtained for ARPSS-Pb based devices. To our best knowledge, this is the highest V OC achieved in the system of perovskite with 1.56 eV energy gap. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Zn-Al co-modified MCM-41 significantly decreased the content of oxygenates and increased the proportions of olefins and aromatics. • Under catalysis with 1 wt% Zn-3 wt% Al/MCM-41, the most significant synergy of aromatics production was observed. • The chemical mechanism of catalytic co-pyrolysis to produce aromatics was ascertained based on the hydrocarbon mechanism, available of acid centres in catalyst, and the Diels-Alder reaction. • The thermogravimetric analysis and kinetic analysis demonstrated the possibility of synergy in the catalytic co-pyrolysis process. This paper investigates separate pyrolysis of corn stalk (CS) and polypropylene (PP) and co-pyrolysis of CS and PP over Zn-Al co-modified MCM-41 to produce aromatics. In the presence of catalysts, the product contents and composition were significantly influenced. Zn and Al showed a certain synergistic effect, under catalysis with 1 wt% Zn-3 wt% Al/MCM-41, and the maximum proportions of aromatics (24.31 %) and the minimum production of oxygenated compounds (12.37 %) were obtained. With Zn-Al co-modified MCM-41, the highest contents of benzene, toluene, xylene, trimethylbenzene, naphthalene, and indene were 1.33, 1.84, 2.31, 1.15, 1.20, and 1.08 times the output of MCM-41, respectively. The catalytic co-pyrolysis of CS and PP also showed a synergistic effect on the production of aromatic hydrocarbons compared with their individual catalytic pyrolysis and the chemical mechanism of that synergy was revealed. Additionally, this synergy ability was further confirmed by thermogravimetric (TG) analysis and kinetic analysis. [ABSTRACT FROM AUTHOR]