Initial Cycle Research Articles

A Stability-Based Management Protocol for Isolated Lateral Malleolar Ankle Fractures at the Level of the Syndesmosis Reduces the Need for Surgical Intervention.

The study aimed to establish and subsequently improve the rate of stability assessments of fractures with uncertain stability and the impact on the avoidance of potentially unnecessary surgery. Two independent audit cycles were conducted from October 2019 to May 2020. All patients had closed isolated lateral malleolar fractures at the level of the tibiotalar syndesmosis involving skeletally mature bone. A stability-based management protocol was introduced, incorporating an education programme and management guideline. 75 ankles fractures were included. In the initial audit cycle, 13 patients did not undergo stability X-rays within 2weeks of injury. Interestingly, only one stability assessment was performed for five operated ankles in the first audit, versus a 100% compliance rate in the second cycle. We observed more accurate documentation following education and awareness of clinical importance. By implementing a stability-based management guideline, there was an improvement in compliance with guidance towards stability assessments of ankle fractures. This potentially led to the avoidance of unnecessary surgery on fractures where stability assessments supported non-operative management.

DEVOPS FOR MANUFACTURING SYSTEMS: SPEEDING UP SOFTWARE DEVELOPMENT

AbstractThe increasing importance of software as an essential functional provider in products and processes requires that companies master the development capabilities to continiously and quickly deliver high-quality software features. DevOps (acronym for Development and Operations) is an essential approach to these capabilities, which has so far been used predominantly in software-driven companies. This paper investigates the conditions under which DevOps can also be used in the industrial context of series manufacturing in order to be able to steadily develop and provide software features used in these environments (e.g. for monitoring and maintenance of manufacturing machines). A concept for DevOps for manufacturing systems was developed based on current best practices and the specific situation in the industrial company. The concept was then implemented and validated with experts on the basis of initial development cycles, demonstrating the usefulness of DevOps for manufacturing systems.

Multi-ion doped P2/O3 biphasic layered oxides cathodes NaxNi0.2Mn0.55Cu0.14TiyZnzO2 for sodium-ion batteries

Layered oxides are the most commonly used cathode materials in sodium ion batteries, typically presented in two structure variations: the sodium-poor P2 and the sodium-rich O3. The P2 structure is generally more stable in comparison to the O3 structure; however, it has lower capacity and initial coulombic efficiency owing to the low content of Na+. Conversely, the O3 structure offers higher operating voltage and capacity, but it is not practical due to its structural instability. To amalgamate the properties of both structures, in our work, we prepared NaxNi0.2Mn0.55Cu0.14TiyZnzO2 (x = 0.67,0.9,1, y + z = 0.11) as the cathode material by a straightforward sol-gel method. Among them, the specific capacity of Na0.9Ni0.2Mn0.55Cu0.14TiyZnzO2 (P2/O3-NMCTZ) is 82.8 mAh·g−1 during the initial discharge cycle at 1 A·g−1. After 500 cycles, the specific capacity is maintained at 65.4 mAh·g−1 with a capacity retention rate of 78.9%. Besides, the material shows a strong pseudo-capacitance effect (89.72%, 90.67%, 93.14%, 93.51%, 94.98% and 96.86%). These results demonstrate the outstanding electrochemical performance of the multi-ion doped P2/O3 hybrid materials, providing new ideas for constructing layered oxides cathode for sodium-ion batteries.

Fluorination of SiOx as an effective strategy to enhance the cycling stability of lithium-ion batteries

Herein, fluorinate silicon monoxide (SiO-F) is prepared by heat treatment of SiO with ammonium bifluoride (NH4HF2) at low temperatures to improve the cycling stability of SiO. The fluorination of SiO is confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier-Transform infrared spectroscopy (FT-IR). The SiO-F exhibits higher initial discharge capacity, rate capability, and cycling stability than untreated SiO (pristine SiO). The superior electrochemical performances of the SiO-F are attributed to the formation of a LiF-rich solid electrolyte interphase (SEI) layer formed by the reaction between Li-ion and F-groups on the surface of SiO during the charge and discharge cycle.

A Scalable and Controllable Li‐Powder‐Coating Prelithiation Method Toward Ultralong‐life and High‐Energy‐Density LiFePO4 Battery

LiFePO4/graphite battery is considered to be the ideal Li‐ion battery for grid energy storage, which requires long cycle life. However, the formation of solid electrolyte interphase (SEI) in the first charge and discharge process and regeneration of SEI during cycling causes continuous loss of active lithium, which reduces the reversible capacity of the battery and shortens its cycle life. Prelithiation of the negative electrode is an effective method to supplement the loss of active lithium, thereby improving the cycle life and energy density of the battery. This work uses stable lithium powder, solid electrolyte (Li6.4La3Zr1.4Ta0.6O12), and polyvinylidene fluoride to prepare a stable prelithiation reagent, which is coated on the surface of a graphite electrode using a microgravure‐coating machine. The effects of the proposed prelithiation method on initial Coulombic efficiency, cycle life, and calendar life of batteries are investigated. It is found that this method can increase the cycle life of graphite/lithium iron phosphate pouch cells, with the initial Coulombic efficiency increased by 3.43%, and is readily applicable for industrial applications.

Mechanical behaviour and acoustic emission characteristics of basalt fibre mortar rubble under uniaxial cyclic compression

To investigate the effect of basalt fibre (BF) content on the mechanical behaviour and damage characteristics of mortar rubble under cyclic loading, uniaxial compression tests and cyclic loading and unloading tests were carried out on specimens fabricated with different BF volume fractions. Based on damage mechanics theory, a damage ontology model of BF mortar rubble was developed. The damage of BF mortar rubble under cyclic loading was identified and analysed using acoustic emission (AE) techniques, and parameters such as the Felicity ratio (FR), ratio of the RA (rise time/amplitude) and the average frequency (RA/AF), response ratio, b-value and peak frequency were used to characterise the failure mechanism of BF mortar rubble. The results of this study revealed that the incorporation of BF increased the compressive strength by 9.3%-14.2%. The response ratios of the initial cycles were 91.2, 53.4 and 24.4 when the BF content was 0.2%, 0.3% and 0.4% respectively. The incorporation of BF helps to delay the onset of critical damage values. The peak frequency signals are concentrated in the region of 50 kHz and 160 kHz. the 50 kHz frequency represents the appearance of fractures in the matrix and the 160 kHz frequency signal represents the occurrence of brittle fractures in the aggregate. The FR trend was a good predictor of damage to the mortar rubble. The damage mode of the mortar rubble changed from tensile fracturing to composite fracturing due to the addition of BF. The performance optimisation concept of mortar rubble proposed in this study provides a reference for the optimal design of BF mortar rubble and thus has a strong application value.

Engineering robust biopolymer-derived carbon growth of Ni-rich cathode materials for high-performance Li-ion batteries

Nickel-rich ternary layered oxide (NCM811) is one of the most promising electrode materials for next-generation lithium ion batteries, offering high reversibility, ecofriendly, and low cost. However, this type of cathode material also has low thermal stability, phase changes during charge-discharge, and safety concerns, requiring considerable improvement to be commercially viable. This study induced carbon growth on a modified nickel-rich layered oxide NCM811 cathode material as positive electrodes for Li ion batteries, and subsequently performed electrochemical, structural, and post-mortem characterization for the material. Specific capacity retention for the best case cathodes improved to 75 % after 100 cycles at 0.1C rate under atmospheric conditions compared with current standard NCM electrodes. Full cell fabricated using that best case electrodes achieved 220 mAh g−1 initial charge capacity, retaining 81 % charge capacity after 50 cycles. Initial coulombic efficiency and cycle stability for the prepared best case cathode material was enhanced by optimum carbon growth due to the reconstructed layer structure's capacity to inhibit side reactions at the interface and stabilize bulk structure over cycles.

Elucidating the Role of Prelithiation in Si‐based Anodes for Interface Stabilization

AbstractPrelithiation as a facile and effective method to compensate the lithium inventory loss in the initial cycle has progressed considerably both on anode and cathode sides. However, much less research has been devoted to the prelithiation effect on the interface stabilization for long‐term cycling of Si‐based anodes. An in‐depth quantitative analysis of the interface that forms during the prelithiation of SiOx is presented here and the results are compared with prelithiaton of Si anodes. Local structure probe combined with detailed electrochemical analysis reveals that a characteristic mosaic interface is formed on both prelithiated SiOx and Si anodes. This mosaic interface containing multiple lithium silicates phases, is fundamentally different from the solid electrolyte interface (SEI) formed without prelithiation. The ideal conductivity and mechanical properties of lithium silicates enable improved cycling stability of both prelithiated anodes. With a higher ratio of lithium silicates due to the oxygen participation, prelithiated SiO1.3 anode improves the initial coulombic efficiency to 94% in full cell and delivers good cycling retention (77%) after 200 cycles. The insights provided in this work can be used to further optimize high Si loading (>70% by weight) based anodes in future high energy density batteries.

Ayurvedic treatment of a case diagnosed as AIDS and diffuse large B cell lymphoma - Case report

Non-Hodgkin's lymphoma (NHL) is recognized as the most common form of lymphoma. Among the various subtypes of NHL, diffuse large B-cell lymphoma (DLBCL) stands out as the predominant type, constituting approximately 30 percent of all lymphomas. DLBCL has an annual incidence rate of 2.9 per 100,000 in men and 1.5 per 100,000 in women in India. It is a rapidly growing and aggressive form of NHL. A 40-year-old male patient presented with a chief complaint of abdominal pain and discomfort persisting for 4-5 months. The patient had previously been diagnosed with AIDS (Acquired immune deficiency syndrome - a retroviral disease) and non-Hodgkin's lymphoma Diffuse Large B-Cell Lymphoma (DLBCL) on 29-04-14. Ileal resection had already been performed on 20-01-2014, and the patient received the initial cycle of CHOP (cyclophosphamide, doxorubicin [Adriamycin], vincristine [Oncovin], prednisolone) chemotherapy on 02-04-14. The MIB index was measured at 70%. The report on 22-04-14 indicated the presence of a few enlarged lymph nodes scattered in the mesentery and paraaortic regions. The patient declined further cycles of chemotherapy. Based on Ayurvedic diagnosis, the patient initially exhibited symptoms resembling Arsha (hemorrhoids) and Gulma (tumor), followed by Grahani Daurbalya (improper digestion). At the time of examination, he had severe Pandu. Considering the pathology and symptomatology, a prescription of Heeraka Bhasma + Chaturmukha Rasa, Triphala + Kapardika Bhasma + Panchamrita Parpati + Patola (Trichosanthus cucmerina) + Dhanvayasa (fegoniacretica), TapyadiLoha + Navyasootashekhara + Vanga + Asthimajja Pachaka (Guduchi + Amalaki + Musta) + Kukkutanakhi (Tectaria coadunate) along with 10 ml of Rohitakarishta and Krimikuthara Rasa was prescribed. After seven months of treatment, the symptoms subsided. No adverse events were reported during the seven-month treatment and follow-up period. In conclusion, this case study demonstrates the safe and effective treatment of these diseases using Ayurveda. It improved the patient's health and quality of life, resolving the issue of swollen lymph nodes. The patient survived for over four years thereafter.

Boosting the electrochemical performance of Li-rich Mn-based cathode materials via oxygen vacancy and spinel phase integration

Li-rich Mn-based oxide cathodes (LMOs) are regarded as one of the most prospective high energy density cathodes due to the reversible anion redox reaction, which gives them a very high capacity. However, LMOs materials usually have problems like low initial coulombic efficiency (ICE) and poor cycling performance during cycling, which are associated with irreversible surface O2 release and unfavourable electrode/electrolyte interface side reactions. Herein, an innovative and scalable NH4Cl-assisted gas–solid interfacial reaction treatment technique is employed to construct oxygen vacancies and spinel/layered heterostructures simultaneously on the surface of LMOs. The synergistic effect of the oxygen vacancy and the surface spinel phase can not only effectively enhance the redox properties of the oxygen anion and inhibit irreversible oxygen release, but also effectively mitigate the side reactions at the electrode/electrolyte interface, inhibit the formation of CEI films and stabilize the layered structure. The electrochemical performance of the treated NC-10 sample improved significantly, showing an increase in ICE from 77.4 % to 94.3 % and excellent rate capability and cycling stability, with a capacity retention of 77.9 % after 400 cycles at 1 C. This oxygen vacancy and spinel phase integration strategy offers an exciting prospect and avenue for improving the integrated electrochemical performance of LMOs.

Parameter optimization strategy of LLC converter soft start-up process based on a simplified numerical calculation model

High-frequency start-up strategy is usually used to limit the current overshoot in the resonant tank of LLC converter. However, the strong coupling among start-up frequency, initial duty cycle, and current limit increases the design complexity of parameters. This paper proposes a parameter optimization strategy of the LLC converter soft start-up process based on the numerical calculation method. With this strategy, the initial switching frequency and duty cycle are determined adaptively according to the given maximum current requirements during the start-up process. The current overshoot is suppressed and soft switching is achieved in the whole process. After the second switching period, 50% duty cycle operation occurs without oscillation. Furthermore, exponential frequency reduction is used in the process, and the current overshoot limiting condition in the initial period is discussed. Finally, a 240 W LLC converter prototype is built to verify the correctness of the theoretical analysis in this paper. In terms of current limiting, soft switching, and initial switching frequency, the comprehensive performance of the soft start-up control strategy proposed in this paper is better. Compared to the traditional control strategy, the current overshoot is reduced by 45.6%. The theoretical calculation, simulation, and experimental results are consistent.

Prussian blue microcubes-derived FeF3 cathodes for high-energy and ultra-stable lithium and lithium-ion batteries

Iron trifluoride (FeF3) is highlighted as a competitive cathode for next-generation lithium and lithium-ion batteries with higher energy densities and lower cost. However, the FeF3 cathode is typically hindered by rapid capacity fade for their poor electronic/ionic conductivity and unstable electrode/electrolyte interphase. Herein, a microcubic FeF3@C composite, where the nanosized FeF3 particles (<40 nm) are encapsulated by graphitized carbon and linked through surrounding amorphous carbon matrix, is firstly synthesized through the Prussian blue microcubes. When using as the cathode of coin-type lithium batteries, it can achieve stable and ultralong lifespan (over 1000 cycles) at FeF3 mass loading of ∼2 mg cm−2, ascribing to the compact and thick wrapping of carbon shell and stable cathode solid electrolyte interphase (CEI) during cycling. Besides, the FeF3–Li pouch cell, FeF3 full batteries with pre-lithiated Li4Ti5O12 (PLLTO) and pre-lithiated mesocarbon microbeads (PLMCMB) anodes are successfully constructed. To interpret the capacity rising of as-prepared FeF3 cathodes within initial cycles, the detailed electrochemical behaviors and electrode kinetics are investigated. The results show that the decay of the high-potential decomposition process cannot catch up with the activation of the low-potential conversion reaction The repeated electrochemical activation within initial cycles causes multiple interface and increased Li+ diffusion coefficient (resulted from the amorphization of FeF3 particle), which induce the capacity rising.

Effect of pre-fatigue on mechanical properties of modified double-base propellant

In this paper, fatigue tests of modified double-base propellant (CMDB) under cyclic loading under constant strain amplitude were carried out by using Dynamic Mechanical Analyser (DMA) at 20°C. The uniaxial tensile stress-strain curves at five strain rates after pre-fatigue were measured by a material universal testing machine, and the curves were similar to the uniaxial tensile test results of unfatigued propellant. The experimental results show that CMDB propellant has obvious strain rate correlation, and the initial elastic modulus and yield strength of the propellant increase with the increase of strain rate. The effect of prefatigue on the stress-strain behavior of CMDB propellant depends largely on the number of initial cycles and the strain stress loading amplitude. Under the initial cycle condition of pre-fatigue, the maximum tensile strength increases slightly with the increase of cycle number, while the elongation at break decreases with the increase of cycle number.

Decent Fast-Charging Performance of Li-Ion Battery Achieved by Modifying Electrolyte Formulation and Charging Protocol

In this work, two strategies have been attempted to achieve decent fast-charging performances of Li-ion batteries. The first is to combine lithium bis(fluorosulfonyl)imide (LiFSI) and dimethoxyethane (DME) into an electrolyte for high ionic conductivity of the bulk electrolyte and the electrolyte-electrode interphases, and the second is to limit charging capacity within 80% state-of-charge (SOC) for stable capacity retention by lowering charging rate without increasing total charging time in the standard constant current-constant voltage (CC-CV) charging protocol. It is found that using 5 wt% fluoroethylene carbonate (FEC) as an additive enables the hybridization of 20 wt% DME into the electrolyte without adverse effects on the initial formation cycles and ongoing cycling in terms of coulombic efficiency and reversible capacity, and adding 2 wt% LiPF6 is beneficial to reducing charge-transfer resistance and stabilizing capacity retention. As a result, decent fast-charging performances are obtained from the 200 mAh graphite/LiNi0.80Co0.15Al0.05O2 pouch cells by using a 1.2 m (molality) LiFSI 3:5:2 ethylene carbonate (EC)/ethylmethyl carbonate (EMC)/DME + 5% FEC + 2% LiPF6 electrolyte (all by wt) and a modified CC-CV charging protocol consisting of CC charging at 4 C for a total of 12 min, which is the charging time equivalent to a 5 C charging protocol.

Assessment of cyclic deformation and critical stress amplitude of jointed rocks via cyclic triaxial testing

Jointed rock specimens with a natural replicated joint surface oriented at a mean dip angle of 60° were prepared, and a series of cyclic triaxial tests was performed at different confining pressures and cyclic deviatoric stress amplitudes. The samples were subjected to 10,000 loading-unloading cycles with a frequency of 8 Hz. At each level of confining pressure, the applied cyclic deviatoric stress amplitude was increased incrementally until excessive deformation of the jointed rock specimen was observed. Analysis of the test results indicated that there existed a critical cyclic deviatoric stress amplitude (i.e. critical dynamic deviatoric stress) beyond which the jointed rock specimens yielded. The measured critical dynamic deviatoric stress was less than the corresponding static deviatoric stress. At cyclic deviatoric stress amplitudes less than the critical dynamic deviatoric stress, minor cumulative residual axial strains were observed, resulting in hysteretic damping. However, for cyclic deviatoric stresses beyond the critical dynamic deviatoric stress, the plastic strains increased promptly, and the resilient moduli degraded rapidly during the initial loading cycles. Cyclic triaxial test results showed that at higher confining pressures, the ultimate residual axial strain attained by the jointed rock specimen decreased, the steady-state dissipated energy density and steady-state damping ratio per load cycle decreased, while steady-state resilient moduli increased.

Prelithiation: A Critical Strategy Towards Practical Application of High‐Energy‐Density Batteries

AbstractTo meet the demand for high‐energy‐density batteries, alloy‐type and conversion‐type anode materials have attracted growing attention due to their high specific capacity. However, the huge irreversible lithium loss during initial cycling significantly reduces the energy density of the full cell, which limits their practical applications. Fortunately, various anode prelithiation techniques have been developed to compensate for the initial lithium loss. At the same time, the cathode prelithiation has been proposed and demonstrated remarkable enhancement in the electrochemical performance, along with excellent scalability and compatibility with the existing battery production processes. Here, recent advances are reviewed in the prelithiation of both anodes and cathodes, and the key challenges are discussed in front of their practical applications. It is aimed to provide better recommendations and assistance for its large‐scale practical applications.

A Systematic Study Aiming Toward Voltage Noise Elimination in Viscoelastic Poly(methyl methacrylate)–Poly(ethylene oxide) Polymer Blend Electrolytes in Li Metal Battery Cells

AbstractRandom appearance of micro short circuits and voltage noise is observed, until now, on initial cycles of solid polymer electrolyte high voltage cathode cells with lithium metal anodes. However, this phenomenon also takes place in lower operation voltages such as those in LiFePO4 cathode cells. Approaching the direct/indirect effect of the cathode, the polymer electrolyte, and the anode parts on this initial dendritic bridging between the electrodes separately, a systematic study is carried out toward determining potential causes of voltage noise and ways of prevention. Electrolytes based on the blend of PMMA–PEO show that relying only on the viscoelastic nature cannot prevent the appearance of voltage noise. Liquid polymers are used for the wetting of the cathode active material that lead to a complete pore infiltration. Having ensured the optimization of the interfacial area between the solid electrolyte and the cathode, studies along the directions of the lithium surface pretreatment and polymer ionic conductivity are examined as a means of dendrite growth suppression and cell cycling capabilities improvement, leading to the observation that methylated PEO chains work in favor of both of these directions.

Enhancing Li cycling coulombic efficiency while mitigating “shuttle effect” of Li-S battery through sustained release of LiNO3

In practical lithium-sulfur batteries (LSBs), the shuttle effect and Li cycling coulombic efficiency (CE) are strongly affected by the physicochemical properties of solid electrolyte interphase (SEI). LiNO3 is widely used as an additive in electrolytes to build a high-quality SEI, but its self-sacrificial nature limits the ability to mitigate the shuttle effect and stabilize Li anode during long-term cycling. To counteract LiNO3 consumption during long-term cycling without using a high initial concentration, inspired by sustained-release drugs, we encapsulated LiNO3 in lithiated Nafion polymer and added an electrolyte co-solvent (1,1,2,2-tetrafluoroethylene 2,2,2-trifluoromethyl ether) with poor LiNO3 solubility to construct high-quality and durable F- and N-rich SEI. Theoretical calculations, experiments, multiphysics simulations, and in-situ observations confirmed that the F- and N-rich SEI can modulate lithium deposition behavior and allow persistent repair of SEI during prolonged cycling. Hence, the F- and N-rich SEI improves the Li anode cycling CE to 99.63% and alleviates the shuttle effect during long-term cycling. The lithium anode with sustainable F- and N-rich SEI shows a stable Li plating/stripping over 2000 h at 1 mA cm−2. As expected, Li||S full cells with this SEI achieved a long lifespan of 250 cycles, far exceeding cells with a routine SEI. The Li||S pouch cell based on F- and N-rich SEI also can achieve a high energy density of about 300 Wh kg−1 at initial cycles. This strategy provides a novel design for high-quality and durable SEIs in LSBs and may also be extendable to other alkali metal batteries.

Computational study of impact wear: Fatigue approach

Impact wear results from the surface failure of engineering components that undergo repetitive contact motion. It reduces their service life. This study investigated the impact wear of alloy steel using computational techniques combined with empirical data. The ultimate objective was to develop an approach requiring low–moderate effort for industrial application using limited resources to predict the average impact wear rate of AISI 4140 alloy steel (one of the most commonly used materials). The wear mechanisms were investigated by scanning electron microscopy (SEM). Indirect monitoring was used to examine the wear stage transition cycle, e.g., from mild to severe wear. The empirical results showed that the transition cycle depended on the impact force. Fatigue was identified as the key damage mechanism, with cracks and lamellar wear appearing under severe deterioration. The average wear rate from the initial impact cycle to the wear stage transition cycle increased as the impact force increased. A simplified computational 2D finite element model assuming a smooth frictionless surface was used to investigate the contact condition. The contact behavior including the stress–strain distribution that developed during first contact was investigated using finite element analysis. A combined empirical and computational approach to predicting average wear rate was developed based on stress distribution data from the FE model and fatigue properties. The prediction results were then validated by comparison with the empirical data. These showed good agreement. The stress amplitude derived from an equivalent high-stress region was also introduced. The predicted curve of average wear rate versus stress amplitude of an equivalent high-stress region improved the design of the component.

Joule heating-assisted tailoring Co-MOC derived chainmail catalyst to regulate peroxymonosulfate activation for tetracycline destruction: Singlet oxygen integrated direct electron transfer pathways

Rational design of stable and high-efficiency non-precious catalysts to activate peroxymonosulfate (PMS) is crucially important for recalcitrant pollutant elimination. In this study, we present a microwave-assisted combustion heat method to fabricate stable Co-MOC-800 as a highly efficient peroxymonosulfate (PMS) activator for tetracycline hydrochloride (TCH) degradation. Joule heating from short-time microwave irradiation enables the expeditious fabrication of Co-based metal–organic-complex (Co-MOC) precursor, which is carbonized to form the representative Co-MOC-800 chainmail catalyst with a maximum degradation rate of 97% in 10 min. This catalyst still possesses an excellent stability with highly remained activity of the initial cycle after five consecutive runs. The N-doped amorphous carbon encapsulated Co nanoparticles integrated Co-Nx sites play an essential role in activating PMS for TCH degradation through non-radial dominant pathways including singlet oxygen and direct electron transfer. Attributing to the non-radical pathways, the Co-MOC-800-catalyzed PMS activation exhibits relatively high anti-interference ability under different solution pH, inorganic anions and humic acid. Three reaction pathways for TCH degradation are proposed by recording the degradation intermediates, and the toxicity of the detected intermediates was evaluated. The present work provides a vivid example for simply fabricating efficient Co-based catalysts for recalcitrant pollutant elimination via activating PMS.