Degradation Time Research Articles

Electrochemical degradation of diclofenac generates unexpected thyroidogenic transformation products: Implications for environmental risk assessment

Diclofenac (DCF) is an environmentally persistent, nonsteroidal anti-inflammatory drug (NSAID) with thyroid disrupting properties. Electrochemical advanced oxidation processes (eAOPs) can efficiently remove NSAIDs from wastewater. However, eAOPs can generate transformation products (TPs) with unknown chemical and biological characteristics. In this study, DCF was electrochemically degraded using a boron-doped diamond anode. Ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry was used to analyze the TPs of DCF and elucidate its potential degradation pathways. The biological impact of DCF and its TPs was evaluated using the Xenopus Eleutheroembryo Thyroid Assay, employing a transgenic amphibian model to assess thyroid axis activity. As DCF degradation progressed, in vivo thyroid activity transitioned from anti-thyroid in non-treated samples to pro-thyroid in intermediately treated samples, implying the emergence of thyroid-active TPs with distinct modes of action compared to DCF. Molecular docking analysis revealed that certain TPs bind to the thyroid receptor, potentially triggering thyroid hormone-like responses. Moreover, acute toxicity occurred in intermediately degraded samples, indicating the generation of TPs exhibiting higher toxicity than DCF. Both acute toxicity and thyroid effects were mitigated with a prolonged degradation time. This study highlights the importance of integrating in vivo bioassays in the environmental risk assessment of novel degradation processes.

An Outsized Contribution of Rivers to Carbon Emissions From Interconnected Urban River‐Lake Networks Within Plains

AbstractUrban aquatic ecosystems in plains are often subject to extensive anthropogenic pollutant inputs and have prolonged times for pollutant degradation, potentially leading to diverse carbon emission patterns. This study explored carbon emission patterns and underlying mechanisms in Ge Lake and its tributaries, located in an urban area within a plain in China. The results revealed that carbon emissions from rivers were significantly higher than those from the downstream lake. Spatial interpolation analysis further revealed that CO2‐eq emissions from a 1‐km2 river area can be equivalent to those from an area as large as 86‐km2 of the downstream lake. Rivers are the gateway for the entry of organic compounds, often carrying substances that are readily biodegradable. As the river water moves slowly, these compounds accumulate and undergo degradation in rivers before they reach downstream lakes. The findings may benefit the estimates of carbon emissions in these regions with greater precision.

Exploring Household Composting as an Effective Solution for Urban Waste Management

Organic wastes are generated from many sources’ compiles, solid waste, food, kitchens wastes, etc. Disposal of solid waste is stinging and widespread problem in both urban and rural areas in many developed and developing countries. Collection and disposal of solid waste is one of the major problems of urban environment in most countries worldwide today. Improper Solid Waste Management causes many environmental problems. Traditional composting methods have been common practices in many rural/sub urban areas and requires more time for complete degradation. Traditional method requires large sites for disposal, which nowadays is not possible, as limited spaces are available in the cities. So, here comes the need to find new techniques such as Home Composting. The research focuses on understanding the effectiveness of household composting as a waste management technique for household garbage. Household composting is an attractive method in which small bins can be used as an alternative to composting sites to a small scale. This technique helps to decompose the organic matter in lesser time than the traditional methods. Addition of compost accelerators in the bins increases the decomposition rate. Simply by home composting, the quantity of waste can be reduced. Key Words: Solid Waste Management, Composting, Compost Accelerators, Home Composting, Household Garbage

Multi-stage exponential model based on subspace clustering distribution for bearing remaining useful life prediction

As one of the key components in rotating machinery, the rolling element bearing has been widely used in actual production, such as wind turbines, vehicles and machine tools. A bearing’s remaining useful life (RUL) is an important indicator for its performance assessment, which is related to maintenance and production safety. To overcome the insensitivity of the conventional health indicator (HI) on bearing degradation assessment, this study proposes a subspace clustering method based on manifold learning to evaluate the evolution of health status, which describes the degenerate distribution via a two-class model and realizes the identification of the degradation of each stage. Motivated by the inconsistent degradation process in the application of actual bearing, this study proposes a multi-stage degradation identification criterion in an adaptive way, which can effectively identify different degradation rates of bearing. Based on the different degradation states, a multi-stage degradation exponential model is established to accurately predict the RUL. The effectiveness of the proposed method is validated through open datasets. The experimental results prove that the proposed method can effectively identify different degradation rates and accurately give the boundary time of the multi-stage degradation. The RUL prediction accuracy is significantly improved compared with traditional HI.

Development and characterization of 3D-printed electroconductive pHEMA-co-MAA NP-laden hydrogels for tissue engineering

AbstractTissue engineering (TE) continues to be widely explored as a potential solution to meet critical clinical needs for diseased tissue replacement and tissue regeneration. In this study, we developed a poly(2-hydroxyethyl methacrylate-co-methacrylic acid) (pHEMA-co-MAA) based hydrogel loaded with newly synthesized conductive poly(3,4-ethylene-dioxythiophene) (PEDOT) and polypyrrole (PPy) nanoparticles (NPs), and subsequently processed these hydrogels into tissue engineered constructs via three-dimensional (3D) printing. The presence of the NPs was critical as they altered the rheological properties during printing. However, all samples exhibited suitable shear thinning properties, allowing for the development of an optimized processing window for 3D printing. Samples were 3D printed into pre-determined disk-shaped configurations of 2 and 10 mm in height and diameter, respectively. We observed that the NPs disrupted the gel crosslinking efficiencies, leading to shorter degradation times and compressive mechanical properties ranging between 450 and 550 kPa. The conductivity of the printed hydrogels increased along with the NP concentration to (5.10±0.37)×10−7 S/cm. In vitro studies with cortical astrocyte cell cultures demonstrated that exposure to the pHEMA-co-MAA NP hydrogels yielded high cellular viability and proliferation rates. Finally, hydrogel antimicrobial studies with staphylococcus epidermidis bacteria revealed that the developed hydrogels affected bacterial growth. Taken together, these materials show promise for various TE strategies. Graphic abstract

Modeling of microplastics degradation in aquatic environments using an experimental plan

The aim of this article is to apply advanced predictive modeling techniques to understand the degradation process of microplastics in aquatic environments. Utilizing a Fractional Factorial Central Composite Experimental Plan, this study seeks to develop precise predictive statistical models that enable forecasting the quantity of pollutants generated during the degradation of microplastics under various environmental conditions. This tool was applied to model changes in DOC (dissolved organic carbon) and DEHP (bis(2-ethylhexyl) phthalate) values during the degradation of microplastics in aquatic ecosystems. The methods were developed using data derived from laboratory tests conducted using the GC-MS technique. The obtained approximating functions, considering factors such as degradation time, water temperature, and particle size, significantly reduced the analysis time. A two-stage verification of the approximating functions was conducted, considering the accuracy of the function form, its adequacy, the statistical significance of input variables, and their correlation with DOC and DEHP. The employed a Fractional Factorial Central Composite Experimental Plan allowed for the simultaneous reduction in the number of experiments and prediction of the influence of variables on the output values. Precise predictive models support understanding of the microplastic degradation process, facilitating the development of effective strategies for managing this pollution.

Prolonged delivery of HIV-1 vaccine nanoparticles from hydrogels

Immunization is a straightforward concept but remains for some pathogens like HIV-1 a challenge. Thus, new approaches towards increasing the efficacy of vaccines are required to turn the tide. There is increasing evidence that antigen exposure over several days to weeks induces a much stronger and more sustained immune response compared to traditional bolus injection, which usually leads to antigen elimination from the body within a couple of days. Therefore, we developed a poly(ethylene) glycol (PEG) hydrogel platform to investigate the principal feasibility of a sustained release of antigens to mimic natural infection kinetics. Eight-and four-armed PEG macromonomers of different MWs (10, 20, and 40 kDa) were end-group functionalized to allow for hydrogel formation via covalent cross-linking. An HIV-1 envelope (Env) antigen in its trimeric (Envtri) or monomeric (Envmono) form was applied. The soluble Env antigen was compared to a formulation of Env attached to silica nanoparticles (Env-SiNPs). The latter are known to have a higher immunogenicity compared to their soluble counterparts. Hydrogels were tunable regarding the rheological behavior allowing for different degradation times and release timeframes of Env-SiNPs over two to up to 50 days. Affinity measurements of the VCR01 antibody which specifically recognizes the CD4 binding site of Env, revealed that neither the integrity nor the functionality of Envmono-SiNPs (Kd = 2.1 ± 0.9 nM) and Envtri-SiNPs (Kd = 1.5 ± 1.3 nM), respectively, were impaired after release from the hydrogel (Kd before release: 2.1 ± 0.1 and 7.8 ± 5.3 nM, respectively). Finally, soluble Env and Env-SiNPs which are two physico-chemically distinct compounds, were co-delivered and shown to be sequentially released from one hydrogel which could be beneficial in terms of heterologous immunization or single dose vaccination. In summary, this study presents a tunable, versatile applicable, and effective delivery platform that could improve vaccination effectiveness also for other infectious diseases than HIV-1.

Determining the preeminent plastic wastes in the production of petrol using pyrolysis method and its effectiveness as an alternative fuel

Abstract: This study aimed to determine which type of plastic – PET, HDPE, LDPE, PP, PS, and Others, produces most oil yield in terms of time of complete degradation, temperature and amount of plastics using a non-catalytic slow pyrolysis method; it also determined the physical characteristics of the oil yield in terms of its color and appearance; and it also aimed to determine which petroleum produced by different types of plastics are more efficient in terms of (a) production of oil and (b) combustion time. Production of oil and oil yield is presented in milliliters and percentage, respectively. Combustion time is expressed in seconds from the time of ignition to total disappearance of flame having 1ml of oil tested from each produced pyrolytic oil. Experimental-descriptive comparative method was used in determining the type of plastic that yields to most of pyrolytic oil. Based from gathered results, at constant temperature and amount of plastics, PS produced most petroleum at 29.5% oil yield followed by PP with 29%. While PET produced the least petroleum with 0.01% oil yield. Color varies at different types of plastics, given that PET and PP produces light brown color, LDPE produces light yellow while HDPE, PS and Others produces black color. PET, HDPE, PP, PS and Others produced liquefied petroleum while LDPE produces flammable wax product. PS produced most petroleum with 295ml (29.5%), and PET produced least oil with 1ml (0.01%). Combustion time varies at different types of plastics: PS at 145 seconds, PP at 141 seconds, HDPE at 115 seconds, Others at 78 seconds, LDPE at 77 seconds while PET produced non – flammable oil yield. Thus, PS is most efficient as an alternative fuel in terms of production and combustion time. For the betterment of similar study, future researchers are encouraged to test the pyrolytic oil yielded from different types of plastics in engine performance and machineries and the comparative performance to the available commercial fuels.

Cytotoxicity and Degradation Resistance of Cryo- and Hydrogels Based on Carboxyethylchitosan at Different pH Values.

Background: The use of chitosan-based gels is still limited due to their restricted solubility in acid solutions, where the molecules have a positive charge. The functionalization of chitosan makes it possible to significantly expand the possibilities of using both the polymer itself and hydrogels based on its derivatives. Objective: To evaluate the effect of the conditions for the production of cryo- and hydrogels based on carboxyethylchitosan (CEC) crosslinked with glutaraldehyde on gel swelling and its resistance to degradation depending on pH and cytotoxic effects and to test the hypothesis that the amount of crosslinking agent during synthesis may affect the cytotoxicity of the gel. Methods: Gels' swelling values and degradation resistance were determined using the gravimetric method. The cytotoxic effect was evaluated during the co-cultivation of gels in the presence of human fibroblasts using light optical microscopy and flow cytometry. Results: All CEC-based cryogels had a higher equilibrium swelling value and degradation time than the CEC hydrogel in the pH range from 4.6 to 8.0. This demonstrates the superiority of cryogels relative to CEC-based hydrogels in terms of swelling potential and degradation resistance, while an increase in the number of crosslinks with glutaraldehyde contributes to longer swelling of the cryogel. The positive control (intact fibroblasts) and all gel samples were statistically identical in the number of viable cells. On the third day, the viability of the fibroblast cells was consistently high (above 95%) and did not differ between all tested CEC-based gels. And in general, the cell morphology analysis results corresponded with the results obtained in the flow cytometry-based cytotoxicity test. We also did not find proof in our experiment to support our hypothesis that the amount of crosslinking agent during synthesis may affect the cytotoxicity of the material.

Effect of porang flour substitution and drying time on the characteristics of instant yellow rice

Instant yellow rice is an alternative breakfast menu with a short serving time while preserving traditional cuisine. Rice as the main ingredient of yellow rice is difficult to replace and has little nutritional content. Making instant yellow rice using the autoclavingfreezing method requires fast drying to minimize nutrient degradation and maximize rehydration time. The study used local tuber substitution of porang as a source of minerals while increasing the nutritional content of instant yellow rice. This study aimed to determine the effect of porang flour substitution and drying time on physical, chemical, and sensory characteristics and to determine the best formula for instant yellow rice with porang flour substitution. This study was conducted using the completely randomized design (CRD) method with two factors, namely variations in the concentration of porang flour (2%, 3% and 4%) and variations in drying time (5 hrs, 6 hrs and 7 hrs). The results of the analysis showed that the concentration of porang flour and drying time showed a significant effect (p<0.05) on the physical, chemical, and sensory characteristics of instant yellow rice. Porang flour substitution and drying time significantly affected rehydration time, expansion volume, moisture content, ash, protein, fat, carbohydrates, and panelists' preference for color attributes. And it has no significant effect on the bulk density and panelists' preferences on aroma, taste, texture, and overall. The best treatment was instant yellow rice with 2% porang flour substitution and drying at 60℃ for 6 hrs. With a high proximate nutritional content, good physical properties, and is well received by the sensory panelists.

Roles of hygrothermal aging temperature and time in degradation of the fracture toughness of highly cross‐linked epoxy

AbstractThe evolution of plane‐strain fracture toughness in highly cross‐linked epoxies was assessed for different hygrothermal aging temperatures (25, 50, and 75°C) and durations (0–75 days). The absorption of water increased with hygrothermal aging, but at a diminishing rate and without saturating. A fraction of the absorbed water persisted despite prolonged drying. Thermogravimetric analysis revealed that the epoxy‐decomposition temperature decreased with hygrothermal aging. 13C solid‐state nuclear magnetic resonance spectroscopy indicated an increase in the de‐shielding of carbon atoms in the vicinity of electronegative elements like oxygen with hygrothermal aging severity, indicating the development of intermolecular hydrogen bonding. X‐ray photoelectron spectroscopy tracked the chemical bonding state of carbon by using a narrow scan on the C1s binding energy region. Upon hygrothermal aging, there was a decrease in CC/CC groups, indicating main chain scission through hydrolysis. A simultaneous increase in the CO species indicates the formation of alcohols as hydrolysis reaction products. In this manner, retained water was involved in hydrogen bonding and chemical reactions with the epoxy. With increasing severity of hygrothermal aging, the fracture toughness decreased. This was consistent with fracture surface micrographs that showed a greater distance amongst crack stretch marks in specimens with less toughness.

Synthesis and characterization of Ag@M-BTC (M = Zn & Cd) Nanocomposites for efficient removal of methylene blue and indigo carmine

Two MOF based composite materials decorated with Ag NPs viz. Ag@M-BTC (BTC= 1,3,5-benzenetricarboxylate; M=Zn & Cd) were synthesised and characterized using various physicochemical techniques, including FT-IR, PXRD, FE-SEM, EDX, HR-TEM, BET and XPS. The FT-IR spectra of the nanocomposites (NCs) and the pristine MOFs suggest retention of the MOF structure in the resulting composite materials and the PXRD patterns confirm the presence of metallic Ag within the crystalline phase of the MOFs. The observed rough surfaces on the NCs as evidenced from FE-SEM micrographs, indicates the deposition of Ag NPs on the surface of the MOFs. Furthermore, HR-TEM images reveal the presence of nanosized Ag aggregates of spherical shape inside the MOF matrix as well as on the surface. The adsorption activity of the synthesised NCs have been assessed for Methylene Blue (MB) and Indigo Carmine (IC). It is observed that the NCs, Ag@Zn-BTC (1a) and Ag@Cd-BTC (2a) performs better degradation as compared to that of pristine MOFs. These NCs can degrade MB completely (100 %) after 50 min treatment time, while maximum 91 % degradation was recorded for the IC dye. Here, the degradation process can be thought of as operating via chemisorption phenomena, supported by theoretical calculations. Additionally, these NCs can be reused up-to three times for the effective degradation of dyes.

Composite ZnFe2O4/SrWO4 hollow microspheres as catalyst for high-performance photo-Fenton degradation

Low degradation rate for a long degradation time and poor cycle stability caused by rapid recombination of generated electron-hole pairs are tough challenges for photo-Fenton degradation The unique microstructure catalyst can provide enough catalytic surface to prevent the recombination of electron-hole pairs and facilitate the barrier-free transport of active species. In addition, the special hollow microsphere structure can effectively accelerate the Rhodamine B (RhB) penetration and the photo-Fenton process. Introducing SrWO4 can increase oxygen vacancies and optimize the electronic structure of ZnFe2O4, thus enhancing electron transport and RhB degradation in the photo-Fenton process. This kind of catalytic material ZnFe2O4/SrWO4 (ZFO/SW) in the photo-Fenton process can effectively degrade the 99.18 % RhB dye only within 20 min with remarkable cycling stability. This work demonstrates the high efficiency of ZFO/SW as a photocatalyst and confirms the contribution of the current design concept to the development of photo-Fenton degradation materials.

Chronic toxic effects of erythromycin and its photodegradation products on microalgae Chlorella pyrenoidosa

The photodegradation products (PDPs) of antibiotics in the aquatic environment received increasing concern, but their chronic effects on microalgae remain unclear. This study initially focused on examining the acute effects of erythromycin (ERY), then explored the chronic impacts of ERY PDPs on Chlorella pyrenoidosa. ERY of 4.0 − 32 mg/L ERY notably inhibited the cell growth and chlorophyll synthesis. The determined 96 h median effective concentration of ERY to C. pyrenoidosa was 11.78 mg/L. Higher concentrations of ERY induced more serious oxidative damage, antioxidant enzymes alleviated the oxidative stress. 6 PDPs (PDP749, PDP747, PDP719, PDP715, PDP701 and PDP557) were identified in the photodegradation process of ERY. The predicted combined toxicity of PDPs increased in the first 3 h, then decreased. Chronic exposure showed a gradual decreasing inhibition on microalgae growth and chlorophyll content. The acute effect of ERY PDPs manifested as growth stimulation, but the chronic effect manifested as growth inhibition. The malonaldehyde contents decreased with the degradation time of ERY at 7, 14 and 21 d. However, the malonaldehyde contents of ERY PDPs treatments were elevated compared to those in the control group after 21 d. Risk assessment still need to consider the potential toxicity of degradation products under long-term exposure.

Ozonated Sunflower Oil Embedded within Spray-Dried Chitosan Microspheres Cross-Linked with Azelaic Acid as a Multicomponent Solid Form for Broad-Spectrum and Long-Lasting Antimicrobial Activity.

Multicomponent solid forms for the combined delivery of antimicrobials can improve formulation performance, especially for poorly soluble drugs, by enabling the modified release of the active ingredients to better meet therapeutic needs. Chitosan microspheres incorporating ozonated sunflower oil were prepared by a spray-drying method and using azelaic acid as a biocompatible cross-linker to improve the long time frame. Two methods were used to incorporate ozonated oil into microspheres during the atomization process: one based on the use of a surfactant to emulsify the oil and another using mesoporous silica as an oil absorbent. The encapsulation efficiency of the ozonated oil was evaluated by measuring the peroxide value in the microspheres, which showed an efficiency of 75.5-82.1%. The morphological aspects; particle size distribution; zeta potential; swelling; degradation time; and thermal, crystallographic and spectroscopic properties of the microspheres were analyzed. Azelaic acid release and peroxide formation over time were followed in in vitro analyses, which showed that ozonated oil embedded within chitosan microspheres cross-linked with azelaic acid is a valid system to obtain a sustained release of antimicrobials. In vitro tests showed that the microspheres exhibit synergistic antimicrobial activity against P. aeruginosa, E. coli, S. aureus, C. albicans and A. brasiliensis. This makes them ideal for use in the development of biomedical devices that require broad-spectrum and prolonged antimicrobial activity.

Accelerated Polymer Photodegradation

Abstract: This article presents preliminary results of the accelerated degradation of polymers using concentrated solar radiation. For this purpose, a passive solar concentration prototype was designed, which consists of four trapezoidal mirrors placed in the shape of an inverted truncated square pyramid. The mirrors are placed at an angle of 30° respect to the zenith. The prototype has a square base of 46 cm x 46 cm where the polymers to be irradiated are placed and a geometric concentration ratio, CRg, of 1.89. The mass change was determined after 30 days of exposure to solar radiation, and the temperature variation of some samples as a function of irradiance was obtained. In addition, a computer simulation was carried out using the free access software Energy2D. Some polymers maintained their flexible mechanical properties, such as PET (type 1), others were partially embrittled, while type 2, 5 and 7 polymers were completely embrittled. It was possible to reduce the degradation time of different types of commercial polymers, while polymers exposed to non-concentrated radiation and without exposure remains intact. Embrittled polymers can be used as waterproof material in slabs and pre-cast walls, as well in applications where they are not exposed to solar radiation. On the other hand, the polymers that remained intact must be used in applications with permanent radiation exposure, such as in flower pots, plastic parts for automobiles, etc.

BIODEGRADATION OF CHITOSAN MEMBRANE SCALES OF HARUAN FISH (Channa striata)-HYDROXYAPATITE IN ARTIFICIAL SALIVA SOLUTION

Background: Membrane materials for surgical procedures using Guided Tissue Regeneration (GTR) are Polytetrafluoroethylene (PTFE) and collagen, but have the disadvantage of requiring further surgical procedures to remove membranes after use and rapid degradation properties. Haruan (Channa striata) fish scale chitosan is expected to be an alternative material for GTR membranes. Purpose: To determine the longer degradation time between chitosan membranes and chitosan+HA membranes in artificial saliva. Methods: This study used true experimental with post test only with control design using three treatments of 5% chitosan, 5% + 2 gr chitosan, and 5% + HA 4 gr of chitosan, positive control of GTR membrane with time intervals of 1, 7, 14, and 21 days in artificial saliva. Results: The results of the Kruskall Wallis test showed that there was a significant difference, the Mann Whitney Post Hoc test yielded 5% chitosan with chitosan+2 gr HA and chitosan+2gr HA with chitosan+4 gr HA had a p value <0.05 p=(0.000) in the 14th day, 5% chitosan with chitosan+4gr HA had a p value <0.05 p=(0.000) significant on days 7 and 14, and the positive control with all treatments had a p value <0.05 p=(0.000) . Conclusion: Chitosan and chitosan+HA membranes resulted in a degradation time of 21 days. Chitosan membrane + 2 g HA membrane was the best treatment because the remaining weight of the membrane was greater than the other treatments.Keywords : Channa striata, Chitosan, Degradation Test, Guided Tissue Regeneration (GTR), Hydroxyapatite, Remaining Membrane Weight

‘Pfft’: Samuel Beckett and the Ecology of Breathing in the Anthropocene

The purpose of this article is to analyse how breathing, illustrated and expanded by Samuel Beckett’s selected works, might be reconsidered as a conceptual category and corporeal phenomenon in the Anthropocene. The paper discusses three instances in Beckett’s corpus where breathing resurfaces as neither exclusively human nor nourishing. It is argued that breathing forms an intricate web of relationships with other human and nonhuman actants. Consequently – and this is especially important in the Anthropocene and the times of environmental degradation – breathing makes collective experience and coexistence deeper and more apparent; yet, this collective dimension also signifies inherent vulnerability rooted in the body’s porosity, as respiration is always threatened with contamination, which might make it frail. In this light, the article includes textual analyses of Breath and Not I, two works that conjoin the deterioration of the world with respiratory crises. The analyses of Beckett’s works are juxtaposed with selected concepts derived from new materialism, object-oriented ontology, and deconstruction. As I argue, reading Beckett and breath in the context of the Anthropocene should draw our utmost attention since it might help us radically alter our thinking as we face possible, if not inevitable, catastrophes that challenge the binary of finitude and continuity and that of life and death.

Controllable hierarchical Bi2MoO6 spheres with ferroelectric polarization enhanced photocatalytic efficiency

AbstractThe fast recombination of photogenerated electrons and holes remains a major issue in hindering photocatalytic efficiency. Apart from traditional methods, such as rare metal deposition and element doping, the introduction of a built‐in electric field has been proven an efficient way in recent years. Ferroelectrics, which possess spontaneous polarization and associated polarization electric fields, are attracting more attention as photocatalysts. In this study, Bi2MoO6 spheres with different hierarchical upper nanostructures are synthesized through a one‐pot hydrothermal method. With this porous structure and the intrinsic ferroelectricity, BMO spheres present excellent physisorption and photodegradation ability toward dye molecules. After corona poling treatment, the ferroelectric field of the BMO samples was enhanced, and the recombination of charges was suppressed, leading to an obvious increase in photocatalytic rate. The origin BMO‐5 can reach a total degradation of RhB in 20 min, and the polarized BMO‐5 (BMO‐5P) can remove all RhB molecules instantly through the physisorption process. Apart from BMO‐5, other samples also present excellent catalytic behavior. Origin BMO‐2 can fully degrade the RhB in 40 min, and the degradation time of polarized BMO‐2P is 30 min. The hierarchical structure and internal polarized electric field endow BMO spheres with outstanding adsorption purification and photodegradation ability and provide a new comprehensive strategy for the catalyst design.

Facile synthesis of mechanically robust and injectable tetra-polyethylene glycol/methacrylate chitosan double-network hydrogel cartilage repair

The development of advanced hydrogel scaffolds with good biocompatibility, mechanical strength and bioactive property is highly desirable in cell growth, proliferation, and differentiation for the cartilage tissue regeneration. Herein, we reported a simple, inexpensive, feasible, and environmentally benign strategy to synthesize a biocompatible polyethylene glycol-based methacrylate-modified chitosan (PCSMA) double network (DN) hydrogel via the reversible Schiff base reaction and successive photopolymerization between the tetra-poly (ethylene glycol) aldehyde (Tetra-PEG-CHO) and methacrylate-modified chitosan (CSMA) in mild conditions. The four-terminated CHO groups were hypothesized to not only construct the whole architectural network through the dynamic pH-responsive Schiff base but also contribute to the injectable behavior and good tissue adhesion, which may furnish the surgeon with the availability of injectable and shapeless ability to fill in the gaps. Compared to the single PCS hydrogel with the main similar components of the tetra-PEG-CHO and pure CS moieties, the post-fabrication of PCSMA DN hydrogel possessed slower degradation time, denser network, and stronger mechanical stability, which could facilitate the bone marrow mesenchymal stem cell (BMSCs) activity and promote the chondrogenic differentiation for facilitating cartilage regeneration. Our study highlights the positive effects on chondrogenic performance and supports the PCSMA hydrogel as a promising tissue-engineered scaffold for the cartilage defect repair.