Kinetic Model Research Articles

Evaluation of characterization and adsorption kinetics of natural organic matter onto nitric acid modified activated carbon

Natural organic substances (NOM) found in drinking water are a major contributor to disinfectant by-product formation and are potentially toxic to humans. Traditional water treatment techniques may not always effectively treat NOMs. Therefore, an advanced treatment method such as adsorption can be inexpensive, simple and efficient. The selected adsorbent's and the NOMs properties both affect the removal effectiveness of the adsorption method. Activated carbon (AC), which is widely used in real-scale water treatment plants, has been modified and used in recent years In order to oxidize the porous carbon surface, raise its acidic qualities, eliminate mineral components, and enhance the surface's hydrophilic qualities. In this research, AC was modified with nitric acid (M-PAC) and NOM removal was investigated. In addition, it is discussed how the modification with nitric acid changes the adsorbent structure and chemistry. A morphology with smooth and irregular voids was observed as a result of nitric acid modification of the original AC by SEM analysis. The particle size increased from 387.65 nm to 502.07 nm for the M-PAC adsorbent. The FTIR spectrum indicates that structures connected to aromatic rings get formed in the M-PAC adsorbent as a result of the modification. The highest NOM removal for the original powdered activated carbon (PAC), 47%, was observed at 36 hours of contact time. On the other hand, M-PAC adsorbent achieved 40% NOM removal at contact times of 72 hours and above. It was concluded that the pseudo-second order kinetic model better represented NOM adsorption for both adsorbents.

The [(NH3)4Cu2O2]2+‐Peroxo Complex as the Key Intermediate for NH3‐SCR Activity and Deactivation of Cu‐CHA Catalysts.

AbstractIn NH3‐SCR over Cu‐CHA catalysts in the low‐temperature range 150–300 °C, the activation of oxygen occurs via oxidation of a pair of mobile (NH3)2CuI‐complexes located in the cages of the zeolite. In this step, a reactive [(NH3)4Cu2O2]2+‐peroxo complex (μ‐η2,η2‐peroxo diamino dicopper(II)‐complex) is formed. The chemistry of this complex determines several catalytic properties of the Cu‐CHA catalyst. The reaction of NO with the [(NH3)4Cu2O2]2+‐peroxo complex governs the NH3‐SCR activity. A reaction of the [(NH3)4Cu2O2]2+‐peroxo complex with ammonia hinders the reaction of NO with the complex, thus leading to an inhibition of the NH3‐SCR reaction. Finally, the deactivation in presence of SO2 is due to a reaction of SO2 with the [(NH3)4Cu2O2]2+‐peroxo complex, leading to the formation of Cu−S compounds in the catalyst. In this review, the characterization and the reactions of the [(NH3)4Cu2O2]2+‐peroxo complex with NO, NH3, and SO2, and mean‐field kinetic models based on first principles calculations for NH3‐SCR activity and SO2 poisoning are discussed.

Calcium-Based Metal-Organic Framework: Detection and Idiosyncratic Removal of Copper by Nano-Particle Deposition.

A novel calcium-based metal-organic framework (CaMOF@LSB) was designed and synthesized, exhibiting dual functionality for both selective detection and removal of Cu2+ ions from aqueous solutions. The framework's stability, including solvent and pH variations, was established with notable thermal resilience. Colorimetric Cu2+ detection (≥5 ppm) with a high capture capacity of 484.2 mg g-1 by CaMOF@LSB places this material among the few that ensure efficient colorimetric detection and high removal capabilities of Cu2+ ions. Batch adsorption experiments revealed pH-dependent behavior and competitive interactions. Langmuir and pseudo-second-order kinetics models aptly described adsorption isotherms and kinetics, respectively. Thermodynamic assessments confirmed spontaneous and endothermic adsorption. Mechanistically, nanoparticle deposition contributes to the Cu2+ uptake. CaMOF@LSB also exhibited one of the best removal behaviour of Cu2+ by means of oxide formation on the surface. Regeneration of CaMOF@LSB was achieved by simple sonication in 0.1 M aqueous NaOH solution. The recyclability was also tested up to 5 cycles, and it exhibited a small decrease in adsorption capacity observed across the cycles. This research presents a promising avenue for addressing heavy metal pollution using metal-organic frameworks, thereby offering potential applications in water purification and environmental pollution monitoring and remediation.

Insights into Error Control Mechanisms in Biological Processes: Copolymerization and Enzyme-Kinetics Revisited.

The high fidelity observed in biological information processing ranging from replication to translation has stimulated significant research efforts to clarify the underlying microscopic picture. Theoretically, several approaches to analyze the error rates have been proposed. The copolymerization theory describes the addition and removal of monomers at the growing tip of a copolymer, leading to a closed set of nonlinear equations. On the other hand, enzyme-kinetics approaches formulate linear equations of biochemical networks, describing transitions between discrete chemical states. However, it is still unclear whether the error values computed by the two approaches agree. Moreover, there are conflicting interpretations on whether the error is under thermodynamic or kinetic discrimination control. In this work, we examine the error rate in persistent copying biochemical processes by specifically analyzing both theoretical approaches. The initial disagreement of the results between the two theories motivated us to rederive the formula for the error rate in the kinetic model. The error computed with the new method resulted in excellent agreement between both theoretical approaches and with Monte Carlo simulations. Furthermore, our theoretical analysis shows that the kinetic discrimination controls the error, even when the energy difference between adding the right and wrong products is very small. Our theoretical investigation gives important insights into the physical-chemical properties of complex biological processes by providing the quantitative framework to evaluate them.

Floating Bimetallic Catalysts for Growing 30cm-Long Carbon Nanotube Arrays with High Yields and Uniformity.

Ultralong carbon nanotubes (CNTs) are considered as promising candidates for many cutting-edge applications. However, restricted by the extremely low yields of ultralong CNTs, their practical applications can hardly be realized. Therefore, new methodologies should be developed to boost the growth efficiency of ultralong CNTs and alleviate their areal density decay at the macroscale level. Herein, a facile, universal, and controllable method for the in-situ synthesis of floating bimetallic catalysts (FBCs) is proposed to grow ultralong CNT arrays with high yields and uniformity. Ferrocene and metal acetylacetonates serve as catalyst precursors, affording the successful synthesis of a series of FBCs with controllable compositions. Among these FBCs, the optimized FeCu catalyst increases the areal density of ultralong CNT arrays to a record-breaking value of ∼8100 CNTs mm-1, and exhibits a lifetime 3.40 times longer than that of Fe, thus achieving both high yields and uniformity. A 30-centimeters-long and high-density ultralong CNT array is also successfully grown with the assistance of FeCu catalysts. As evidenced by our kinetic model and molecular dynamics simulations, the introduction of Cu into Fe can simultaneously improve the catalyst fluidity and decrease carbon solubility, and an optimal catalytic performance will be achieved by balancing this tradeoff. This article is protected by copyright. All rights reserved.

Probabilistic and maximum entropy modeling of chemical reaction systems: Characteristics and comparisons to mass action kinetic models.

We demonstrate and characterize a first-principles approach to modeling the mass action dynamics of metabolism. Starting from a basic definition of entropy expressed as a multinomial probability density using Boltzmann probabilities with standard chemical potentials, we derive and compare the free energy dissipation and the entropy production rates. We express the relation between entropy production and the chemical master equation for modeling metabolism, which unifies chemical kinetics and chemical thermodynamics. Because prediction uncertainty with respect to parameter variability is frequently a concern with mass action models utilizing rate constants, we compare and contrast the maximum entropy model, which has its own set of rate parameters, to a population of standard mass action models in which the rate constants are randomly chosen. We show that a maximum entropy model is characterized by a high probability of free energy dissipation rate and likewise entropy production rate, relative to other models. We then characterize the variability of the maximum entropy model predictions with respect to uncertainties in parameters (standard free energies of formation) and with respect to ionic strengths typically found in a cell.

Kinetic Model of Fluorescein Release through Bioprinted Polylactic Acid Membrane.

Polylactic acid (PLA)-based cylindrical membranes for the controlled release of fluorescein sodium salt (FS) were prepared by bioprinting on systems with an initial FS concentration of 0.003763 gdm-3 and 37.63 gdm-3, and the drug release process was monitored in a bath at 37 °C. Photographs, acquired at regular intervals during the process, revealed marked osmotic swelling of the polymer. Osmotic swelling consists in the enlargement of the polymer structure and due to the influx of water molecules across the membrane. The cylindrical PLA membrane starts to significantly swell once a certain threshold range is crossed. Important amounts of FS can dissolve under these radically changed circumstances, and the dissolved FS molecules are mobile enough to diffuse out of the cylinder, thus allowing drug release. As a matter of fact, in this investigation, we ascertained that polymer swelling promotes the mass transport phenomenon by altering the conditions for drug dissolution and diffusion, hence facilitating FS release after a specific lag time. Furthermore, in order to compare the release kinetics, the half-release time, t0.5, was taken into consideration. The data of this study evidence that, while increasing the initial concentration of FS by three orders of magnitude, the time parameter, t0.5, is only reduced by 5/6. In addition, the yield of the release process is drastically reduced due to the strong aggregation ability of the dye. Finally, it is demonstrated that a compressed exponential kinetic model fits the experimental data well despite the varying physical conditions.

Partitioning to ordered membrane domains regulates the kinetics of secretory traffic.

The organelles of eukaryotic cells maintain distinct protein and lipid compositions required for their specific functions. The mechanisms by which many of these components are sorted to their specific locations remain unknown. While some motifs mediating subcellular protein localization have been identified, many membrane proteins and most membrane lipids lack known sorting determinants. A putative mechanism for sorting of membrane components is based on membrane domains known as lipid rafts, which are laterally segregated nanoscopic assemblies of specific lipids and proteins. To assess the role of such domains in the secretory pathway, we applied a robust tool for synchronized secretory protein traffic (RUSH, Retention Using Selective Hooks) to protein constructs with defined affinity for raft phases. These constructs consist solely of single-pass transmembrane domains (TMDs) and, lacking other sorting determinants, constitute probes for membrane domain-mediated trafficking. We find that while raft affinity can be sufficient for steady-state PM localization, it is not sufficient for rapid exit from the endoplasmic reticulum (ER), which is instead mediated by a short cytosolic peptide motif. In contrast, we find that Golgi exit kinetics are highly dependent on raft affinity, with raft preferring probes exiting the Golgi ~2.5-fold faster than probes with minimal raft affinity. We rationalize these observations with a kinetic model of secretory trafficking, wherein Golgi export can be facilitated by protein association with raft domains. These observations support a role for raft-like membrane domains in the secretory pathway and establish an experimental paradigm for dissecting its underlying machinery.

Kinetic modeling for upgrading of heavy crude oil via thermal cracking in porous media: SARA fractions and gas compositions

Pyrolysis is regarded as the primary reaction for heavy crude oil upgrading during ISC process, and gas compositions produced by this reaction is also gaining attention. It is critical to establish the kinetic model to predict all products. The kinetic of heavy oil upgrading was studied and all experiments were carried out in an autoclave at 350–450 °C, 0.5 MPa, and 1–10 h. An improved kinetic including SARA fractions, coke, and gas compositions was proposed be more detailed description of the reaction process. Smaller SSE and bigger coefficients of determination (>0.99) of parity plots suggested the accuracy of calculated parameters of the improved kinetic model. The sensitivity analysis results demonstrate that the obtained kinetic parameters represent the optimal values. Gas prediction, a neglected aspect in previous studies, was also addressed, further enhancing the model’s utility.

Helix Formation from Hydrogen Bond Kinetics in Alanine Homopeptides

We present an analysis of α-helix folding in the coarse-grained coordinate of number of formed helical hydrogen bonds (NHBs) for four alanine peptides (ALA)n, with n = 5, 8, 15, and 21 residues. Starting with multi-microsecond all-atom molecular dynamics trajectories in aqueous solution, we represent the system dynamics in a space of between four (for ALA5) and twenty (for ALA21) hydrogen-bonding microstates. In all cases, transitions changing the hydrogen bond count by 1–2 dominate and the coil formation, NHB 1 → 0, is the fastest process. The calculation of global maximum weight paths shows that, when analyzed at a sufficiently long lag time, folding in the NHB coordinate is consecutive, with direct folding, 0 → 3, for ALA5 and bottlenecks at transitions 4 → 6 for ALA8, 0 → 5 for ALA15, and 0 → 9 for ALA21. Further coarse-graining to 2–4 dimensions was performed with the optimal dimensionality reduction method, allowing the identification of crucial folding intermediates and time scales of their formation in ALA8, ALA15, and ALA21. The detailed analysis of hydrogen bonding patterns revealed that folding is initiated preferentially at both peptide termini. The kinetic model was also used to estimate diffusion and friction coefficients for helix propagation. The description of the helix formation process in the hydrogen bonding coordinate NHB was in good general agreement with the experimental data and qualitatively similar to previous kinetic models of higher dimensions based on structural clustering. Use of the low-dimensional hydrogen bonding picture thus provides a different, complementary way of describing the complex and fascinating mechanism of helix formation.

Evaluating SiO2/Al2O3/poly(acrylic acid-co-glycidyl methacrylate) composite as a novel adsorbent for cobalt(II) radionuclides

Abstract A novel SiO2/Al2O3/poly(acrylic acid-co-glycidyl methacrylate), SiO2/Al2O3/P(AA-co-GMA), composite was synthesized and evaluated for its effectiveness in adsorbing Co(II) ions from aqueous solutions. The composite was analyzed using various techniques including FTIR, SEM, TGA, DTA, and XRD. The composite displays a high specific surface area of 17.451 m2/g, exceeding that of the corresponding copolymer, which measures 0.236 m2/g. Batch adsorption experiments were conducted to investigate the factors influencing the adsorption capacity of the composite for Co(II) ions. In the pH experiments, it was found that at a solution pH of 3.4, the P(AA-co-GMA) copolymer alone showed limited capability in adsorbing Co(II) ions, achieving only 3.82 mg/g. However, upon integration of SiO2/Al2O3 into the polymer matrix, the composite exhibited a significantly enhanced adsorption capacity of 103.54 mg/g. The adsorption process followed a pseudo-second-order kinetic model and attained equilibrium within 60 min. The Langmuir isotherm model was found to best describe the adsorption behavior, with a maximum adsorption capacity of 217.86 mg/g. The adsorption of Co(II) was significantly affected by the ionic strength, especially with Al3+ displaying a more pronounced impact on the adsorption of Co(II) ions compared to Na+, Ca2+, and Mg2+. Thermodynamic studies indicate that the adsorption process was spontaneous and endothermic. Overall, the SiO2/Al2O3/P(AA-co-GMA) composite material displayed significant adsorption ability for Co(II) ions, making it a suitable option for further development as an effective adsorbent in water treatment applications.

Kinetic Model for the Desensitization of G Protein-Coupled Receptor.

Desensitization of G-protein-coupled receptors (GPCR) is a general regulatory mechanism adopted by biological organisms against overstimulation of G protein signaling. Although the details of the mechanism are extensively studied, it is not easy to gain an overarching understanding of the process constituted by a multitude of molecular events with vastly differing time scales. To offer a semiquantitative yet predictive understanding of the mechanism, we formulate a kinetic model for the G protein signaling and desensitization by considering essential biochemical steps from ligand binding to receptor internalization. The internalization, followed by receptor depletion from the plasma membrane, attenuates the downstream signal. Together with the kinetic model and its full numerics of the expression derived for the dose-response relation, an approximated form of the expression clarifies the role played by the individual biochemical processes and allows us to identify four distinct regimes for the downregulation that emerge from the balance between phosphorylation, dephosphorylation, and the cellular level of β-arrestin.

The Impact of Dialysate Flow Rate on Hemodialysis Adequacy: A Systematic Review and Meta-Analysis

Abstract Background Patients with kidney failure treated with maintenance hemodialysis (HD) require appropriate small molecule clearance. Historically, a component of measuring ‘dialysis adequacy’ has been quantified using urea kinetic modeling that is dependent on the HD prescription. However, the impact of dialysate flow rate on urea clearance remains poorly described in vivo and its influence on other patient important outcomes of adequacy is uncertain. Methods We searched EMBASE, MEDLINE, and the Cochrane Library from inception until April 2022 for randomized controlled trials and observational trials comparing a higher dialysate flow rate (800 mL/min) and lower dialysate flow rate (300 mL/min) with a standard dialysis flow rate (500 mL/min) in adults (age ≥ 18 years) treated with maintenance HD (>90 consecutive days). We conducted a random effects meta-analysis to estimate pooled mean difference in dialysis adequacy as measured by Kt/V or urea reduction ratio (URR). Results A total of 3118 studies were identified. Of those, 9 met eligibility criteria and 4 were included in meta-analysis. A higher dialysate flow rate (800 mL/min) increased single pool Kt/V by 0.08 (95% CI: 0.05 to 0.10, p-value < 0.00001), and URR by 3.38 (95% CI: 1.97 to 4.78, p-value < 0.00001) in comparison to a dialysate flow rate of 500 mL/min. Clinically relevant outcomes including symptoms, cognition, physical function and mortality were lacking and studies were generally at a moderate risk of bias due to issues with randomization sequence generation, allocation concealment and blinding. Conclusion A higher dialysate flow increased urea-based markers of dialysis adequacy. Additional high-quality research is needed to determine the clinical, economic and environmental impacts of higher dialysate flow rates.

A novel mercapto-functionalized bimetallic Zn/Ni-MOF adsorbents for efficient removal of Hg(II) in wastewater

Heavy metals, especially mercury ions, pose extreme hazards to human health and environmental sustainability. Receiving significant interest lately, metal-organic frameworks with mercapto-functionalization (SH-MOFs) have shown impressive efficacy in effectively eliminating highly hazardous Hg(II) from wastewater. In this investigation, a novel mercapto-functionalized Zn/Ni bimetallic MOF (ZNM-2) was synthesized utilizing a simple solvothermal technique employing zinc and nickel as metal sources and 2-mercaptobenzimidazole (MBI) as the organic ligand. The Hg(II) adsorption capacity by ZNM-2 reached 744.4 mg/g, surpassing that of a single-nickel MOF (NM) 328.8 mg/g. More impressively, ZNM-2 successfully eliminated 99.99 % of Hg(II) from actual water samples, achieving a concentration level for Hg(II) that is lower than the threshold of 1.0 μg/L specified in the GB 5749–2022 drinking water standard. When the pH of Hg(II) solution ranged from 2.0 to 6.0, it exhibited exceptional adsorption capacity and sustained high removal efficiency throughout four consecutive regeneration cycles. The adsorption mechanisms observed in this study were found to conformity with the Langmuir model and PSO kinetic model, suggesting that the predominant mode of Hg(II) adsorption is through a chemisorption process occurring at a monolayer level. The superior Hg(II) removal rate of ZNM-2 can be attributed to the predominant coordination of Hg(II) to the thiol (-SH) groups, as revealed by a combination of FT-IR, XPS analysis, and DFT calculations. Therefore, ZNM-2 is an efficacious Hg(II) absorbent that provides a novel approach to alleviate mercury contamination in wastewater.

Degradation of atrazine by ionizing radiation coupled with persulfate oxidation: Mechanism, pathway and toxicity assessment

The ubiquitous existence of atrazine (ATZ) in aquatic environments has aroused intense concerns, regarding its potential harmful effects on human health and ecology safety. Ionizing radiation has now drawn increasing attention in wastewater treatment. However, its unsatisfactory mineralization performance has significantly hindered the practical applications. Herein, the gamma radiation combined with persulfate oxidation (gamma/PS) system has been innovatively engineered to facilitate the removal of ATZ. Results showed that ATZ (10 mg/L) can be completely removed by gamma radiation with 1.0 kGy dose, and the pseudo-first-order kinetic model provided an good fit for the degradation. Gamma radiation can effectively remove ATZ with initial concentrations ranging from 5–20 mg/L, over a broad pH range (3.2–10.5), with the co-existence of inorganic anions (including CO32-, NO3-, and SO42-) and humic acid, and in actual waters (tap water and surface water). Degradation pathways of ATZ were proposed according to density functional theory (DFT) calculation and LC-MS analysis, including alkylic-hydroxylation, alkylic-oxidation, and dechlorination-hydroxylation. Moreover, gamma radiation was promising to reduce the toxicity of ATZ. Compared with the gamma radiation alone process, the gamma/PS system exhibited satisfactory ATZ removal performance. The k value rose by 4.78 times when PS (1 mM) was added, and TOC removal efficiency increased from 6.48 % to 34.53 % when PS was 4 mM. •OH and SO4•- participated in ATZ degradation, with •OH dominating. These results demonstrated that gamma/PS is a potential approach to degrade ATZ.

Elucidating solvent effects on lipase-catalyzed peroxyacid synthesis through activity-based kinetics and molecular dynamics.

Peroxyacid synthesis is the first step in Prilezhaev epoxidation, which is an industrial method to form epoxides. Motivated by the development of a kinetic model as a tool for solvent selection, the effect of solvent type and acid chain length on the lipase-catalyzed peroxyacid synthesis was studied. A thermodynamic activity-based ping-pong kinetic expression was successfully applied to predict the effect of the reagent loadings in hexane. The activity-based reaction quotients provided a prediction of solvent-independent equilibrium constants. However, this strategy did not achieve satisfactory estimations of initial rates in solvents of higher polarity. The lack of compliance with some assumptions of this methodology could be confirmed through molecular dynamics calculations i.e. independent solvation energies and lack of solvent interaction with the active site. A novel approach is proposed combining the activity-based kinetic expression and the free binding energy of the solvent with the active site to predict kinetics upon solvent change. Di-isopropyl ether generated a strong interaction with the enzyme's active site, which was detrimental to kinetics. On the other hand, toluene or limonene gave moderate interaction with the active site rendering improved catalytic yield compared with less polar solvents, a finding sharpened when peroctanoic acid was produced.

Predicting Long-Time-Scale Kinetics under Variable Experimental Conditions with Kinetica.jl.

Predicting the degradation processes of molecules over long time scales is a key aspect of industrial materials design. However, it is made computationally challenging by the need to construct large networks of chemical reactions that are relevant to the experimental conditions that kinetic models must mirror, with every reaction requiring accurate kinetic data. Here, we showcase Kinetica.jl, a new software package for constructing large-scale chemical reaction networks in a fully automated fashion by exploring chemical reaction space with a kinetics-driven algorithm; coupled to efficient machine-learning models of activation energies for sampled elementary reactions, we show how this approach readily enables generation and kinetic characterization of networks containing ∼103 chemical species and ≃104-105 reactions. Symbolic-numeric modeling of the generated reaction networks is used to allow for flexible, efficient computation of kinetic profiles under experimentally realizable conditions such as continuously variable temperature regimes, enabling direct connection between bottom-up reaction networks and experimental observations. Highly efficient propagation of long-time-scale kinetic profiles is required for automated reaction network refinement and is enabled here by a new discrete kinetic approximation. The resulting Kinetica.jl simulation package therefore enables automated generation, characterization, and long-time-scale modeling of complex chemical reaction systems. We demonstrate this for hydrocarbon pyrolysis simulated over time scales of seconds, using transient temperature profiles representing those of tubular flow reactor experiments.

Microbial detoxification of chlorpyrifos, profenofos, monocrotophos, and dimethoate by a multifaceted rhizospheric Bacillus cereus strain PM38 and its potential for the growth promotion in cotton.

Bacillus genera, especially among rhizobacteria, are known for their ability to promote plant growth and their effectiveness in alleviating several stress conditions. This study aimed to utilize indigenous Bacillus cereus PM38 to degrade four organophosphate pesticides (OPs) such as chlorpyrifos (CP), profenofos (PF), monocrotophos (MCP), and dimethoate (DMT) to mitigate the adverse effects of these pesticides on cotton crop growth. Strain PM38 exhibited distinct characteristics that set it apart from other Bacillus species. These include the production of extracellular enzymes, hydrogen cyanide, exopolysaccharides, Indol-3-acetic acid (166.8μg/mL), siderophores (47.3μg/mL), 1-aminocyclopropane-1-carboxylate deaminase activity (32.4μg/mL), and phosphorus solubilization (162.9μg/mL), all observed at higher concentrations. This strain has also shown tolerance to salinity (1200mM), drought (20% PEG-6000), and copper and cadmium (1200mg/L). The amplification of multi-stress-responsive genes, such as acdS, ituC, czcD, nifH, sfp, and pqqE, further confirmed the plant growth regulation and abiotic stress tolerance capability in strain PM38. Following the high-performance liquid chromatography (HPLC) analysis, the results showed striking compatibility with the first kinetic model. Strain PM38 efficiently degraded CP (98.4%), PF (99.7%), MCP (100%), and DMT (95.5%) at a concentration of 300ppm over 48h at 35°C under optimum pH conditions, showing high coefficients of determination (R2) of 0.974, 0.967, 0.992, and 0.972, respectively. The Fourier transform infrared spectroscopy (FTIR) analysis and the presence of opd, mpd, and opdA genes in the strain PM38 further supported the potential to degrade OPs. In addition, inoculating cotton seedlings with PM38 improved root length under stressful conditions. Inoculation of strain PM38 reduces stress by minimizing proline, thiobarbituric acid-reactive compounds, and electrolyte leakage. The strain PM38 has the potential to be a good multi-stress-tolerant option for a biological pest control agent capable of improving global food security and managing contaminated sites.

Antibacterial and Osteogenic Doxycycline Imprinted Bioglass Microspheres to Combat Bone Infection.

Currently, postoperative infection is a significant challenge in bone and dental surgical procedures, demanding the exploration of innovative approaches due to the prevalence of antibiotic-resistant bacteria. This study aims to develop a strategy for controlled and smart antibiotic release while accelerating osteogenesis to expedite bone healing. In this regard, temperature-responsive doxycycline (DOX) imprinted bioglass microspheres (BGMs) were synthesized. Following the formation of chitosan-modified BGMs, poly N-isopropylacrylamide (pNIPAm) was used for surface imprinting of DOX. The temperature-responsive molecularly imprinted polymers (MIPs) exhibited pH and temperature dual-responsive adsorption and controlled-release properties for DOX. The temperature-responsive MIP was optimized by investigating the molar ratio of N,N'-methylene bis(acrylamide) (MBA, the cross-linker) to NIPAm. Our results demonstrated that the MIPs showed superior adsorption capacity (96.85 mg/g at 35 °C, pH = 7) than nonimprinted polymers (NIPs) and manifested a favorable selectivity toward DOX. The adsorption behavior of DOX on the MIPs fit well with the Langmuir model and the pseudo-second-order kinetic model. Drug release studies demonstrated a controlled release of DOX due to imprinted cavities, which were fitted with the Korsmeyer-Peppas kinetic model. DOX-imprinted BGMs also revealed comparable antibacterial effects against Staphylococcus aureus and Escherichia coli to the DOX (control). In addition, MIPs promoted viability and osteogenic differentiation of MG63 osteoblast-like cells. Overall, the findings demonstrate the significant potential of DOX-imprinted BGMs for use in bone defects. Nonetheless, further in vitro investigations and subsequent in vivo experiments are warranted to advance this research.

Reduction of nitrogen loss in runoff from sloping farmland by a ridged biochar permeable reactive barrier with vegetated filter strips

IntroductionEutrophication due to nitrogen (N) loss from sloping farmland has a high risk in the Three Gorges Reservoir. Biochar and vegetated filter strips (VFS) are used to control nutrient runoff and increase soil water-holding capacity, soil nutrient retention, and crop yield. However, surface biochar application has limited ability to control N loss, especially from sloping farmland.MethodsIn this study, different widths of ridged biochar permeable reactive barrier (RB-PRB) with VFS were employed to intercept N loss in runoff from sloping farmland. Adsorption characteristics of biochar for nitrate and ammonium N were evaluated using isothermal and kinetic adsorption models before field experiments. N index values for ammonium (NH4+), nitrate (NO3−), dissolved N (DTN), particulate N (PN), and total N (TN) lost through runoff were monitored from April 2019 to January 2020.ResultsNO3− and NH4+ sorption on biochar was predominantly physical adsorption with a maximum capacity of 4.51 and 4.12 mg g-1, respectively. During the research period, the dominant transportation pathway of N loss involved dissolved total N movement through subsurface flow, which accounted for 65.55% of the total loss. TN loss for CK was 1954 g·hm-2, while RB-PRB and VFS decreased N loss from sloping farmland by 36.7%. The interception efficiency of RB-PRB was highest at 0.3 m width. VFS successfully intercepted particulate N and reduced it by 32.75%. In terms of soil nutrients, the RB-PRB and VFS interventions led to a substantial 41.69% increase in the TN content of the soil at a 0.4 m width.DiscussionThe findings suggest that biochar has a favorable adsorption effect on NH4+ and NO3−, an appropriate width of RB-PRB with VFS could effectively reduce nitrogen loss from sloping farmland. Simultaneously, it enhances the water and fertilizer retention capacity of sloping cropland soil; however, the long-term implications necessitate further validation.