Degradation Rate Research Articles

Metabolic pathway analysis of the biodegradation of cellulose by Bacillusvelezensis

A green strategy that using Bacillus velezensis to degrade cellulose in bamboo forest waste was demonstrated. The cultivation conditions of microorganism, identified as Bacillus velezensis by 16S rDNA, were optimized by response surface methodology (RSM). Results showed that with a temperature of 35 °C, a pH of 6 in a Luria-Bertani (LB) medium, and a rotation speed of 140 r/min, the bamboo forest waste powder was added to the purified bacteria at a dose of 1 % (w/v), the cellulose degradation rate reached the highest value of 33.12 %. Besides, the fourier-transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and liquid chromatography-mass spectrometry (LC-MS) indicated that cellulose could be effectively degraded, with possible products including cellobiose, uridine diphosphate (UDP)-glucose, D-glucuronic acid, etc. The metabolic pathways involved in cellulose degradation by this strain include the pentose phosphate, starch, sucrose, and glucuronic acid pathways.

Solar photocatalytic degradation of model naphthenic acids mixtures by Bi2WO6 and Bi2WO6/NiO/Ag: Exploring the influence of inorganic fraction of oil sands process water

This study investigates the comparative photocatalytic degradation of six model naphthenic acids, key organic constituents responsible for the toxicity of oil sands process water, using the semiconductor photocatalysts Bi2WO6 and Bi2WO6/NiO/Ag in both buffered solution and the inorganic fraction of OSPW. The heterojunction catalyst (Bi2WO6/NiO/Ag) exhibited the highest removal efficiencies for these organic pollutants with k values 0.048, 0.036, 0.019, 0.283, 0.026, and 0.075 min−1 for 1-adamantanecarboxylic acid, cyclohexanecarboxylic acid, tetrahydropyran-4-carboxylic acid, tetrahydro-2H-thiopyran-4-carboxylic acid, isonipecotic acid, and 4,5-dihydronaphtho[1,2-b]thiophene-2-carboxylic acid, respectively. Experimental analysis suggested that chloride and bicarbonate inhibited the photocatalytic degradation of the target naphthenic acids, while nitrate could accelerate the production of aminyl radicals, enhancing the degradation of isonipecotic acid. Notably, four additional nitrated and hydroxylated by-products were identified during 1-adamantanecarboxylic acid degradation in the presence of nitrate. The addition of the catalyst not only accelerated the degradation rate of 1-adamantanecarboxylic acid but also helped mitigate the formation of potentially toxic by-products. Additionally, the transformation products of 4,5-dihydronaphtho[1,2-b] thiophene-2-carboxylic acid were identified. Degradation pathways were further elucidated with the assistance of density functional theory calculations, identifying the β-carbon as the initial reactive site, with the sulfur atom also playing a significant role in reactivity. These findings contribute to the understanding of the water matrix-induced transformation process of model naphthenic acids during photocatalytic treatment, enhancing the environmental applicability of photocatalytic treatments.

Effect of biochar application on physiochemical properties and nitrate degradation rate in a Siliciclastic Riverine Sandy soil

This study investigated the efficacy of biochar as a soil amendment for enhancing soil physicochemical properties and solute transport dynamics, with implications for agricultural sustainability and environmental stewardship. Batch laboratory experiments and column studies were conducted to assess the effects of biochar application on soil parameters and solute transport under saturated conditions. The saturation soil extraction approach was employed in batch leaching tests, while column experiments replicated subsurface conditions. Transport modeling using CXTFIT 2.1 elucidated solute dispersion dynamics in biochar-amended soils. Batch experiments revealed significant alterations in soil pH, electrical conductivity, and nutrient release following biochar addition. Biochar exhibited adsorption capacity for fluoride ions and released dissolved organic carbon, highlighting its potential for soil carbon sequestration and microbial activity. Column studies demonstrated enhanced solute dispersion and increased microbial activity in biochar-amended soils, as evidenced by changes in breakthrough curves and degradation rates of nitrate. Indeed, nitrate first-order degradation coefficients were 9.08E-06 for the column with only sandy soil, 3.09E-05 and 1.47E-04 for the columns with minimum and maximum doses of biochar respectively. Biochar application significantly influenced soil physicochemical properties and solute transport dynamics, with potential implications for nutrient management and contaminant attenuation in agricultural systems. Despite limitations in laboratory-scale experiments, this research provides valuable insights into biochar-soil interactions. It underscores the need for further investigation under field conditions to validate findings and optimize biochar management practices for sustainable soil and environmental management.

Multifunctional air filter with enhanced filtration, formaldehyde degradation, and antibacterial properties using PET, PDA, and RGO-TiO2

Currently, most air filters, such as polyester (PET) fiber non-woven fabric, only have a single function of particulate filtration. However, the removal of substances harmful to human health, such as volatile organic compounds (VOCs) and bacteria, is becoming increasingly important in indoor air purification. Herein, based on the biomimetic surface functionalization properties of polydopamine (PDA) and the photocatalytic degradation of organic matter and the antibacterial effect of RGO (reduced graphene oxide)-TiO2, a multifunctional NWP2/PET-PDA-RGO-TiO2(P/PPRT) filter with a sandwich structure was prepared for formaldehyde degradation, aerosol filtration, and bactericidal operation. The P/PP2R0.05T20 maintains optimal performance of photocatalytic reaction kinetics and reaches a formaldehyde degradation rate of higher than 79 % within 300 min in the 7th cycle of usage. Compared with the base subtracts, P/PP2R0.05T20 has the highest filtration efficiency of 88.57–99.18 % for 0.3–10 µm particles, respectively, and has a filtration efficiency of higher than 74 % for 0.3 µm particles in the 7th cycles of usage. The quality factor of P/PP2R0.05T20 is improved significantly due to the sandwich structure. The effect of loaded particulate on the catalyst for photocatalytic degradation of formaldehyde was also studied. It was found that the photocatalytic formaldehyde degradation rate of P/PP2R0.05T20 is about 81.8 % within 300 min under different A2 particulate load content. In addition, P/PP2R0.05T20 has a bioaerosol removal rate of higher than 98 % against E. coli. This study provides a practical approach to preparing a multifunctional air filter with the performance of aerosol filtration, photocatalytic degradation of formaldehyde, and bactericidal function using PET non-woven fabric.

Selective phthalate removal by molecularly imprinted biomass carbon modified electro-Fenton cathode

A novel molecularly imprinted biomass carbon (MIP@BC) catalyst functionalized with the virtual template of phthalates was designed as the cathode material which possesses excellent 2-electron oxygen reduction ability and H2O2 production capacity, which is suitable for targeted degradation of phthalates in the electro-Fenton system. Following molecularly imprinted modification, the adsorption capacity of MIP@BC for Dimethyl phthalate (DMP) increased by 40 %, reached 9.26 mg/g. Compared with non-imprinted biomass carbon (NIP@BC), the MIP@BC-mediated electro-Fenton process enhanced the degradation rate of DMP by 72 %. Additionally, the degradation rate of DMP rises by 51 % and 104 % respectively on the basis of river water and domestic sewage. The reactive oxygen species that induced DMP degradation were OH and O2− and targeted adsorption and catalysis exert a synergistic effect. This study provides a new insight into targeted degradation for high-toxicity of emerging contaminants from complex aqueous environment.

Recent replenishment of aliphatic organics on Ceres from a large subsurface reservoir.

Ceres hosts notable aliphatic-organic concentrations, ranging from approximately 5 to >30 weight % in specific surface areas. The origins and persistence of these organics are under debate due to the intense aliphatic organic signature and radiation levels in Ceres' orbit, which would typically lead to their destruction, hindering detection. To investigate this, we conducted laboratory experiments to replicate how the signature of the organic-rich regions would degrade due to radiation. Our findings indicate a fast degradation rate, implying the exposure of buried organics within the past few million years. This degradation rate, coupled with observed quantities, implies that the aliphatics must be present in substantial quantities within the shallow subsurface. Our estimates suggest an initial aliphatic abundance 2 to 30 times greater than currently observed, surpassing significantly the levels found in carbonaceous chondrites, indicating either a significant concentration or remarkable purity.

Zinc and chitosan-enhanced β-tricalcium phosphate from calcined fetal bovine bone for mandible reconstruction.

Mandibular defects pose significant challenges in reconstructive surgery, and scaffold materials are increasingly recognized for their potential to address these challenges. Among various scaffold materials, Beta-tricalcium phosphate (β-TCP) is noted for its exceptional osteogenic properties. However, improvements in its biodegradation rate and mechanical strength are essential for optimal performance. In this study, we developed a novel β-TCP-based scaffold, CFBB, by calcining fetal bovine cancellous bone. To enhance its properties, we modified CFBB with Chitosan (CS) and Zinc (Zn), creating three additional scaffold materials: CFBB/CS, CFBB/Zn2+, and CFBB/Zn2+/CS. We conducted comprehensive assessments of their physicochemical and morphological properties, degradation rates, biocompatibility, osteogenic ability, new bone formation, and neovascularization both in vitro and in vivo. Our findings revealed that all four materials were biocompatible and safe for use. The modifications with CS and Zn2+ significantly improved the mechanical strength, osteogenic, and angiogenic properties of CFBB, while concurrently decelerating its resorption rate. Among the tested materials, CFBB/Zn2+/CS demonstrated superior performance in promoting bone regeneration and vascularization, making it a particularly promising candidate for mandibular reconstruction. The CFBB/Zn2+/CS scaffold material, with its enhanced mechanical, osteogenic, and angiogenic properties, and a controlled resorption rate, emerges as a highly effective alternative for the repair of oral mandible defects. This study underscores the potential of combining multiple bioactive agents in scaffold materials to improve their functionality for specific clinical applications in bone tissue engineering.

Polyglycerol Sebacate/polycaprolactone/reduced graphene oxide composite scaffold for myocardial tissue engineering

The aim of this research was to fabricate and evaluate polyglycerol sebacate/polycaprolactone/reduced graphene oxide (PGS-PCL-RGO) composite scaffolds for myocardial tissue engineering. Polyglycerol sebacate polymer was synthesized using glycerol and sebacic acid prepolymers, confirmed by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Six PGS-PCL-RGO composite scaffolds (S1-S6) with various weight ratios were prepared in chloroform (CF) and acetone (Ace) solvents at 8 CF:2Ace and 9 CF:1Ace volume ratios, using the electrospinning method at a rate of 1 ml/h and a voltage of 18 kV. The scaffolds' chemical composition and microstructure were characterized by FTIR, XRD, and scanning electron microscopy (SEM). Further investigations included tensile testing, contact angle testing, four-point probe testing for electrical conductivity, degradation testing, and cytotoxicity testing (MTT). The results showed that adding 2%wt RGO to the composite scaffold decreased fiber diameter and degradation rate, while increasing electrical conductivity and ductility. The 33%PGS-65%PCL-2%RGO (S3) composite scaffold exhibited the lowest degradation rate (23.87 % over 60 days) and the highest electrical conductivity (51E-3 S/m). Mechanical evaluations revealed an elastic modulus of 2.46 MPa and elongation of 62.43 %, aligning closely with the heart muscle's elastomeric properties. The contact angle test indicated that the scaffold was hydrophilic, with a water contact angle of 61 ± 2°. Additionally, the cell toxicity test confirmed that scaffolds containing RGO were non-toxic and supported good cell viability. In conclusion, the 33%PGS-65%PCL-2%RGO composite scaffold exhibits mechanical and structural properties similar to heart tissue, making it an ideal candidate for myocardial tissue engineering.

A platinum degradation reaction model for the high-speed computation in the integrated fuel cell system simulator and its validation by the accelerated stress test data of the commercial fuel cells

A model to estimate the Pt degradation rate and the numerical methods for high-speed computation were developed for the year-long and system-scale durability simulation in an acceptable accuracy and computational time. The parameters in the model were determined to reproduce the published accelerated stress test (AST) data with the 1 cm2 MEA of 2nd-generation MIRAI (MIRAI-2), state-of-the-art commercial fuel cell electric vehicle. Accuracy of the simulation results was validated by the published data of the ASTs with the FC stack having 13 cells of MIRAI-2, which consists of the 30000 startup-shutdown cycles in 0–0.88 V and 73000 acceleration-deceleration cycles in 0.6–0.9 V. The experimental and simulation results of the residual fractions of the electrochemical surface area in the cathode catalyst layer after the ASTs were 68 and 69 %, respectively, and they agreed in an acceptable accuracy. It was confirmed from the AST simulation with the different initial particle size distributions that even the small number of the coarse particles significantly accelerated the Pt degradation. The developed model was integrated to the FC system simulator the current authors had presented and a remarkable computational speed for the year-long and system-scale durability simulation was demonstrated with a normal laptop computer.

A platinum degradation reaction model for the high-speed computation in the integrated fuel cell system simulator and its validation by the accelerated stress test data of the commercial fuel cells

A model to estimate the Pt degradation rate and the numerical methods for high-speed computation were developed for the year-long and system-scale durability simulation in an acceptable accuracy and computational time. The parameters in the model were determined to reproduce the published accelerated stress test (AST) data with the 1 cm2 MEA of 2nd-generation MIRAI (MIRAI-2), state-of-the-art commercial fuel cell electric vehicle. Accuracy of the simulation results was validated by the published data of the ASTs with the FC stack having 13 cells of MIRAI-2, which consists of the 30000 startup-shutdown cycles in 0–0.88 V and 73000 acceleration-deceleration cycles in 0.6–0.9 V. The experimental and simulation results of the residual fractions of the electrochemical surface area in the cathode catalyst layer after the ASTs were 68 and 69 %, respectively, and they agreed in an acceptable accuracy. It was confirmed from the AST simulation with the different initial particle size distributions that even the small number of the coarse particles significantly accelerated the Pt degradation. The developed model was integrated to the FC system simulator the current authors had presented and a remarkable computational speed for the year-long and system-scale durability simulation was demonstrated with a normal laptop computer.

Chemofunctionalization of knitted silk to improve interface connection in a nano/micro scaffold based on polycaprolactone-chitosan-multi-walled carbon nanotube/silk.

Nano/micro hybrid scaffolds in long-term healing tissue engineering can simultaneously offer both mechanical and biological properties. In this study, a hybrid scaffold was fabricated through electrospinning of polycaprolactone (PCL)-chitosan (Cs)/ multi-walled carbon nanotubes (MWCNTs) based nanofibers onto a chemically functionalized knitted silk substrate (F-Silk) and the scaffold were evaluated with regard to morphology, chemical and crystalline structure, hydrophilicity, mechanical properties, bioactivity, biodegradability, and cellular behavior. Chemical functionalization of silk using N-hydroxysuccinimide (NHS) and 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) resulted in greater integrity in the formation of nanofibers onto the microfibers. The presence of MWCNTs significantly reduced the contact angle of the scaffolds from 79.72°±2.72 to 68.92°±5.63. Chemical functionalization of silk, the presence of nanofiber coating, and the presence of MWCNTs increased the ultimate tensile strength of the hybrid scaffolds by 18%, 20%, and 30% compared to raw silk fabric, respectively. The presence of MWCNTs and chemical functionalization of knitted silk increased the bioactivity and reduced the degradation rate of hybrid scaffolds. The increase in the amount of carboxyl groups as a result of adding 0.5wt% of MWCNTs significantly improved the adhesion, growth and proliferation of chondrocyte cells on the hybrid scaffolds as observed through cell morphology. According to the obtained results, hybrid scaffold based on PCL-Cs-MWCNTs/F-silk can be a suitable option for further research in cartilage tissue engineering.

Exploring the formation of S-scheme heterojunctions in CuFe2O4/Bi2MoO6 porous cubes for photocatalytic removal of tetracycline

Exploring highly active and noble metal-free photocatalysts for the efficient photocatalytic degradation of antibiotics is of great significance. The CuFe2O4 nanostructured cube is synthesized by using a self-sacrificial template strategy, and two-dimensional Bi2MoO6 nanosheets are grown on the surface of CuFe2O4 through a solvothermal method to construct CuFe2O4/Bi2MoO6 S-scheme heterostructure. The CuFe2O4/Bi2MoO6 composite material exhibits eminent photocatalytic activity for the degradation of TC under simulated sunlight, with the optimal ratio CFO/BMO-2 achieving a degradation rate of 98.54 % within 30 min (initial concentration of TC: 50 mg L−1). In addition, CFO/BMO-2 also has excellent magnetic recyclability and cycling ability. Rice cultivation tests demonstrate that the biotoxicity of TC is effectively removed. Density functional theory calculations and in-situ irradiated X-ray spectroscopy deeply reveal the mechanisms of charge separation and transfer of S-scheme heterojunctions in CuFe2O4/Bi2MoO6. The construction of S-scheme heterojunctions promotes the separation of photo-induced charge carriers and improves photocatalytic degradation performance by retaining holes and electrons with strong redox ability. The work provides a practicable method for constructing efficient spinel photocatalysts to drive wastewater treatment reactions, and the constructed magnetically recyclable photocatalysts have certain practical application potential.

Preparation and release pattern study of long-term controlled release Blonanserin microspheres

To prepare a PLGA microsphere loaded with the antipsychotic Blonanserin without release leg period and released in a near-zero model for long time, in this study, 15 kDa and 75 kDa PLGA were chosen to be mixed with different ratios, and Blonanserin microspheres (Bn-MS) without significant differences in the particle size, drug loading capacity, and encapsulation rate were prepared by microfluidics. The release kinetic model was fitted to the release behavior by monitoring the changes in particle size and morphology during the Bn-MS release to investigate microspheres’ in vitro release pattern. The results showed that the addition of appropriate ratios of mixed molecular weights to Bn-MS could eliminate the release hysteresis period. When the ratio of 15 kDa and 75 kDa was 1:9 (F3), the Bn-MS had a low burst release rate, moderate release rate, no release hysteresis period, a long release period of up to 35 days, and a stable release pattern close to the zero level. The results of the release mechanism study indicated that the hybrid PLGA improved the release behavior of the microspheres by adjusting the dissolution degradation rate of Bn-MS, which in turn affected the release mechanism of the microspheres.

Water purification and biological efficacy of green synthesized Co/Zn-Doped α-Fe2O3 nanoparticles

In the present study, Co/Zn doped α-Fe2O3 (Hematite) nanoparticles (NPs) were synthesized using polyvinylpyrrolidone (PVP) and Azadirachta indica (AI) leaves aqueous extract. The analytical techniques including XRD, UV, SEM, EDX, VSM, Raman, and FTIR, we were able to identify and characterize the structural, morphological and magnetic attributes of the synthesized NPs. The findings demonstrated that the synthesized NPs exhibit homogeneous spherical shapes with particle sizes ranging from 8.64 to 15.32 nm. The NPs have rhombohedral crystal lattices, with crystallite sizes of 23.25 nm for chemically synthesized doped α-Fe2O3 NPs and 12.52 nm for those synthesized using green methods. The magnetic study has shown that the saturation magnetization (Ms) value of NPs, which ranges from 36 to 45 emu/g at ambient temperature, exhibits superparamagnetic properties (300 K). The treatment of industrial wastewater and its reuse for agricultural purposes are the subjects of the current study. Different concentrations of doped α-Fe2O3 NPs were used as photocatalysts to degrade dyes in a bioreactor under UV light in a heterogeneous mixture. The degradation rates achieved were 96.42 % for Congo Red (CR) and 98.36 % for Eosin Yellow (EY). DPPH assays were conducted to evaluate the antioxidant activity of the synthesized doped α-Fe2O3 NPs. The percentage inhibition of DPPH radicals ranged from 71.13 % to 90.35 %. Our findings indicate that AI leaf extract holds promise as a valuable resource for the development of bioactive compounds and environmentally friendly approaches to synthesizing green NPs. This is primarily attributed to the increased accessibility of bioactive components with potent antioxidant properties. The combination of these benefits provides opportunities for novel uses in environmental cleanup, biological applications, and energy conversion.

Fabrication of ultrafine Himalayan walnut oil Pickering emulsions by ultrasonic emulsification: Techno-functional properties of emulsions and microcapsules

In present scenario, much of the attention has been put on the production and utilization of Pickering emulsions deciphering enhanced stability and applicability over wide environmental conditions. In this context the present study was carried out to elaborate effect of different wall materials and pH systems on the physicochemical, structural and morphological properties of Himalayan walnut oil Pickering emulsions by ultrasonic emulsification. In this study, concentrated Pickering emulsion of Himalayan walnut oil (HWO) was prepared utilizing soy protein isolate (SPI), maltodextrin (MD) stabilized by pectin at varying concentrations and pH systems (4.0, 7.0). With increase in pectin and SPI concentration and lowering MD, stable emulsions were obtained as deciphered by an Emulsion stability index (ESI) of 100 for 7 days at ambient storage. HWO Pickering emulsions were analysed for particle size measurements (2.13–13.64 µm) and depicted negative zeta potential values (−3.70 to −18.58). Lyophilized HWO microcapsules depicted moderate encapsulation efficiency (44.69–57.63 %) whereas the hygroscopicity values of the microcapsule ranged from (0.21–12.10 %). Thermogravimetric analysis (TGA) of the samples depicted the temperature of maximum degradation rate up to 550 °C whereas XRD spectra depicted amorphous nature of oil microcapsules. FTIR spectra revealed a close association between the SPI-MD-Pectin matrix. SEM analysis revealed stable oil globules entrapped in protein-polysaccharide matrix with no visible cracks and fissures.

Ab initio study of iron-doped zinc oxide for efficient dye degradation

First principle calculations were performed on iron doped zinc oxide (Fe-ZO) to reduce its bandgap to optimize its visible light absorption. The doping of iron in the ZO is done via supercells of Zn1-xFexO. The doped systems are analyzed using generalized gradient approximation plane wave pseudopotential on density functional theory, or local density approximation and LDA + U with PBE. The computational analysis reveals that the bandgap reduced with increasing dopant concentration. Furthermore, a robust absorption is observed toward the visible region of the spectrum. This enhances its ability as a photochemical material to increase degradation rates of industrial grade dyes.

Construction of a novel Z-scheme FeTiO3/MOF-derived In2S3 catalyst for visible-light-driven photo-Fenton degradation of pollutants

The rapid recombination rate of photoexcited carriers for iron titanate (FeTiO3) is still limited the process performance of photo-Fenton. This article reports the successful synthesis of the highly efficient Z-scheme FeTiO3/MOF-derived In2S3 photocatalyst using the hydrothermal method, compensating for the susceptibility of FeTiO3 photo-generated carriers to complexation to a certain extent. A series of characterization have been carried out to explore the structure, morphology and composition of FeTiO3/MOF-derived In2S3 heterostructure. The 0.5 FeTiO3/MOF-derived In2S3 exhibits the excellent photo-Fenton performance for TCH, Cr6+ and OTC, the degradation rate constants (k2) are up to 0.6297 L·mg−1·min−1, 1.332 L·mg−1·min−1, and 0.427 L·mg−1·min−1, respectively. Active species capture experiments and electron paramagnetic resonance (EPR) spectra show that photo-generated holes (h+) and superoxide radicals (·O2-) are present in the photo-Fenton system. The superior photo-Fenton performance is mainly manifested in the following: the MOF-derived In2S3 micro-floral carrier extends the reaction interface of 0.5 FM-I; FeTiO3 effectively enhances the photo-absorption ability of 0.5 FM-I in visible range; the construction of Z-scheme FeTiO3/MOF-derived In2S3, forming the new carriers transport channels and enhancing the generation of ·O2- and ·OH. This experimental exploration provided a reasonable experimental basis for the preparation of efficient photocatalysts.

Synergistic effects of bacteria, enzymes, and cyclic mechanical stresses on the bond strength of composite restorations

Predicting how tooth and dental material bonds perform in the mouth requires a deep understanding of degrading factors. Yet, this understanding is incomplete, leading to significant uncertainties in designing and evaluating new dental adhesives. The durability of dental bonding interfaces in the oral microenvironment is compromised by bacterial acids, salivary enzymes, and masticatory fatigue. These factors degrade the bond between dental resins and tooth surfaces, making the strength of these bonds difficult to predict. Traditionally studied separately, a combined kinetic analysis of these interactions could enhance our understanding and improvement of dental adhesive durability. To address this issue, we developed and validated an original model to evaluate the bond strength of dental restorations using realistic environments that consider the different mechanical, chemical, and biological degradative challenges working simultaneously: bacteria, salivary esterases, and cyclic loading. We herein describe a comprehensive investigation on dissociating the factors that degrade the bond strength of dental restorations. Our results showed that cariogenic bacteria are the number one factor contributing to the degradation of the bonded interface, followed by cyclic loading and salivary esterases. When tested in combinatorial mode, negative and positive synergies towards the degradation of the interface were observed. Masticatory loads (i.e., cycling loading) enhanced the lactic acid bacterial production and the area occupied by the biofilm at the bonding interface, resulting in more damage at the interface and a reduction of 73 % in bond strength compared to no-degraded samples. Salivary enzymes also produced bond degradation caused by changes in the chemical composition of the resin/adhesive. However, the degradation rates are slowed compared to the bacteria and cyclic loading. These results demonstrate that our synergetic model could guide the design of new dental adhesives for biological applications without laborious trial-and-error experimentation.

Toxicological assessment of reactive blue 19 dye aqueous solutions under UV-LED light

Abstract The dye-contaminated industrial effluent causes serious health issues when it gets mixed with underground water without primary treatment. The current project was designed to treat reactive blue-19 dye aqueous solutions in the presence of hydrogen peroxide (H2O2) and titanium dioxide (TiO2) under UV-LED light. The characterization of the photocatalyst was carried out via X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) for structure, purity, and surface study. The effect of various factors such as pH, TiO2 dose, UV-LED light exposure time, H2O2, and dye concentration, on the degradation rate and cytotoxicity reduction was evaluated and optimized through the Response Surface Methodology (RSM). The maximum degradation of dye solution and chemical oxygen demand (COD) reduction was achieved at 98.81 and 86.22 %, respectively for 50 ppm solution, using UV-LED/H2O2(3 %)/TiO2(6 g/L) hybrid process. The toxicity evaluation through the Allium cepa test demonstrated a 62.40, 65.2, and 56.97 % increase in root length (RL), root count (RC), and mitotic index (MI), respectively, following treatment with the UV-LED/H₂O₂/TiO₂ combined process for 150 min. The hemolytic and brine shrimp tests revealed a reduction in toxicity up to 92.18 and 84.08 %, respectively, after applying the same treatment. Additionally, the Ames test indicated up to 80.94 % reduction in mutagenicity for TA98 and an 84.04 % reduction for TA100 strain when dye samples were treated with UV-LED light in the presence of H₂O₂ and TiO₂ for 150 min. The findings suggested that UV-LED light in conjunction with H2O2 and TiO2 can be a useful tool for the degradation and detoxification of toxic pollutants found in textile wastewater.

From aromatic rings to aliphatic compounds - degradation of duloxetine with the use of visible light driven Z-scheme photocatalyst

The growing consumption of antidepressants, associated with their high chemical stability and low biodegradability, become a serious problem for aquatic environment. Many of their components are resistant to conventional water treatment technologies. The photocatalytic processes with the use of semiconductors becoming attractive methods of drugs degradation because the highly reactive species: electrons, holes, hydroxyl radicals (⦁OH) and superoxide anion radicals (O2⦁−) generated under illumination may be involved directly or indirectly in decomposition of complicated organic molecules.In this work we have shown for the first time that Z-scheme photocatalyst, consisted of bismuth vanadate (BiVO4), graphitic-like carbon nitride (g-C3N4) and Au nanoparticles (Au NPs) as a charge transfer mediator, is very efficient in degradation of duloxetine (DLX). We performed the comprehensive evaluation focused not only on degradation rate, mechanism of photocatalytic process, but also identification of decomposition products and the pathways of DLX degradation. Due to application of the elaborated Z-scheme photocatalyst, the degradation rate constant was more than 2-3 times higher than that obtained for photolysis, but more important, the final compounds were mainly aliphatic products, formed by opening of aromatic rings. The chemical structure of the degradation products were determined with the use of HPLC and LC-MS. The toxicity of photoproducts with respect to water organisms was tested by means of Spirotox and Microtox assays. The Microtox test indicated that toxicity of the products after 6h of the solution irradiation in the presence of Z-scheme photocatalyst is about 4 times lower than that after photolysis.