Activation Site Research Articles

Glucagon-like peptide-1 increases heart rate by a direct action on the sinus node.

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are increasingly used to treat type 2 diabetes and obesity. Albeit cardiovascular outcomes generally improve, treatment with GLP-1 RAs is associated with increased heart rate, the mechanism of which is unclear. We employed a large animal model, the female landrace pig, and used multiple in vivo and ex vivo approaches including pharmacological challenges, electrophysiology, and high-resolution mass spectrometry to explore how GLP-1 elicits an increase in heart rate. In anaesthetized pigs, neither cervical vagotomy, adrenergic blockers (alpha, beta, or combined alpha-beta blockade), ganglionic blockade (hexamethonium), nor inhibition of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels (ivabradine) abolished the marked chronotropic effect of GLP-1. GLP-1 administration to isolated perfused pig hearts also increased heart rate, which was abolished by GLP-1 receptor blockade. Electrophysiological characterization of GLP-1 effects in vivo and in isolated perfused hearts localized electrical modulation to the atria and conduction system. In isolated sinus nodes, GLP-1 administration shortened the action potential cycle length of pacemaker cells and shifted the site of earliest activation. The effect was independent of HCN blockade. Collectively, these data support a direct effect of GLP-1 on GLP-1 receptors within the heart. Consistently, single nucleus RNA sequencing showed GLP-1 receptor expression in porcine pacemaker cells. Quantitative phosphoproteomics analyses of sinus node samples revealed that GLP-1 administration leads to phosphorylation changes of calcium cycling proteins of the sarcoplasmic reticulum, known to regulate heart rate. GLP-1 has direct chronotropic effects on the heart mediated by GLP-1 receptors in pacemaker cells of the sinus node, inducing changes in action potential morphology and the leading pacemaker site through a calcium signalling response characterized by PKA-dependent phosphorylation of Ca2+ cycling proteins involved in pacemaking. Targeting the pacemaker calcium clock may be a strategy to lower heart rate in people treated with GLP-1 RAs.

Fe-N co-doped carbon nanofibers with Fe3C decoration for water activation induced oxygen reduction reaction

ABSTRACT Proton activity at the electrified interface is central to the kinetics of proton-coupled electron transfer (PCET) reactions in electrocatalytic oxygen reduction reaction (ORR). Here, we construct an efficient Fe3C water activation site in Fe-N co-doped carbon nanofibers (Fe3C-Fe1/CNT) using an electrospinning-pyrolysis-etching strategy to improve interfacial hydrogen bonding interactions with oxygen intermediates during ORR. In situ Fourier transform infrared spectroscopy and density functional theory studies identified delocalized electrons as key to water activation kinetics. Specifically, the strong electronic perturbation of the Fe–N4 sites by Fe3C disrupts the symmetric electron density distribution, allowing more free electrons to activate the dissociation of interfacial water, thereby promoting hydrogen bond formation. This process ultimately controls the PCET kinetics for enhanced ORR. The Fe3C-Fe1/CNT catalyst demonstrates a half-wave potential of 0.83 V in acidic media and 0.91 V in alkaline media, along with strong performance in H2-O2 fuel cells and Al-air batteries.

Rational design of waste anode graphite-derived carbon catalyst to activate peroxymonosulfate for atrazine degradation

As the rapidly growing number of waste lithium-ion batteries (LIBs), the recycling and reutilization of anode graphite is of increasing interest. Converting waste anode graphite into functional materials may be a sensible option. Herein, a series of carbonaceous catalysts (TG) were successfully prepared using spent anode graphite calcined at various temperatures and applied for activating peroxymonosulfate (PMS) to degrade atrazine (ATZ). The catalyst obtained at 800 °C (TG-800) showed the optimum performance for ATZ removal (99.2% in 6 min). Various experimental conditions were explored to achieve the optimum efficiency of the system. In the TG-800/PMS system, free radicals (e.g., SO4·−, HO·), singlet oxygen (1O2), together with a direct electron transfer pathway all participated in ATZ degradation, and the ketonic (CO) group was proved as the leading catalytic site for PMS activation. The potential degradation routes of ATZ have also been presented. According to the toxicity assessment experiments, the toxicity of the intermediate products decreased. The reusability and universal applicability of the TG-800 were also confirmed. This research not only provides an efficient PMS activator for pollutant degradation, but also offers a meaningful reference for the recovery of waste anode graphite to develop environmentally functional materials.

In situ activation of peroxymonosulfate with bioelectricity for sulfamethoxazole sustainable removal

Conventional electrochemical activation of peroxymonosulfate (PMS) is not very cost-effective and practical by the excessive input of energy. The electricity generated by photosynthetic microalgae fuel cells (MFCs) is utilized to activate PMS, which would achieve the combination of green bioelectricity and advanced oxidation processes for sustainable pollutants degradation. In this study, a novel dual-chamber of MFCs was constructed by using microalgae as anode electron donor and PMS as cathode electron acceptor, which was operating under both close-circuit and open-circuit conditions. Under close-circuit condition, 1–12 mM PMS in cathode was successfully in situ activated, where 32.00%–99.83% of SMX was removed within 24 h, which was about 1.21–1.78 times of that in the open-circuit of MFCs. Meanwhile, a significant increase in bioelectricity generation in MFCs was observed after the accumulation of microalgae biomass (4.65–5.37 mg/L), which was attributed to the efficient electron separation and transfer. Furthermore, the electrochemical analysis demonstrated that SMX or its products were functioned as electronic shuttles, facilitating the electrochemical reaction and altering the electrical capacitance. The quenching experiments and voltage output results reflected that complex active radical (SO4⋅-, ⋅OH, and 1O2) were involved in SMX removal. Seven degradation products of SMX were detected and S–N bond cleavage was the main degradation pathway. Predicted toxicity values calculated by ECOSAR program showed that all the products were less toxic or nontoxic. Finally, the density functional theory (DFT) calculations revealed that the O and N atoms on SMX were more susceptible to electrophilic reactions, which were more vulnerable to be attacked by reactive species. This study provided new insights into the activation of PMS by bioelectricity for SMX degradation, proposing the mechanisms for PMS activation and degradation sites of SMX.

Internal sites of actuation and activation in thin elastic films and membranes of finite thickness.

Functionalized thin elastic films and membranes frequently feature internal sites of net forces or stresses. These are, for instance, active sites of actuation, or rigid inclusions in a strained membrane that induce counterstress upon externally imposed deformations. We theoretically analyze the geometry of isotropic, flat, thin, linearly elastic films or membranes of finite thickness, laterally extended to infinity. At the mathematical core of such characterizations are the fundamental solutions for localized force and stress singularities associated with corresponding Green's functions. We derive such solutions in three dimensions and place them into the context of previous two-dimensional calculations. To this end, we consider both no-slip and stress-free conditions at the top and/or bottom surfaces. We provide an understanding for why the fully free-standing thin elastic membrane leads to diverging solutions in most geometries and compare these situations to the truly two-dimensional case. A no-slip support of at least one of the surfaces stabilizes the solution, which illustrates that the divergences in the fully free-standing case are connected to global deformations. Within the aforementioned framework, our results are important for associated theoretical characterizations of thin elastic films, whether supported or free-standing, and of membranes subject to internal or external forces or stresses.

Peanut-shell-derived biochar mediated peracetic acid activation for the elimination of acetaminophen via an electron-transfer regime

Biochar-based heterogeneous activation of disinfectant peracetic acid (PAA) is an attractive and promising route for micropollutant elimination in water, yet the underlying activation mechanism is still scarce. In this study, PAA was first catalyzed by peanut shell-derived biochar (PSBC) to degrade acetaminophen (ACP). The enhancement of ACP removal was triggered by PAA activation, while the coexisted H2O2 was unexpected to be an adverse factor owing to its occupation of active sites. Higher dosages of PSBC (0–0.30 g/L) and PAA (0–4.0 mM) favored the destruction of ACP, and the activation energy (41.8 kJ/mol) of PSBC/PAA system is lower than that of the thermal or microwave activated PAA system. The experimental results demonstrate that the metastable complex PSBC-PAA* dominated ACP elimination through an electron transfer mechanism. The surface –OH group was validated to be the key active site for PAA activation. Surprisingly, the actual water matrices present a negligible effect and the promotion of HCO3− ion on ACP removal was even observed. Based on the identified intermediates, the transformation of ACP was further proposed with the formation of polymeric products via oxidative coupling reactions. The findings not only shed light on the mechanism of PAA activated by the biochar-based catalyst but also contribute to a novel perspective on future PAA studies in contamination remediation.

Enhancing in-situ tetracycline degradation in urine environment using boron-modified sewage sludge biochar: Mechanism of carbonate radical promotion

In this work, we reveal the influencing factors and mechanisms of tetracycline removal by peroxydisulfate activated with boron-modified sewage sludge biochar in urine. Advanced characterization techniques showed that the introduced BCO2 and BC2O were the main activation sites for peroxydisulfate, which maintained a high removal rate of tetracycline in synthetic and actual urine (86.48% and 77.35%). HCO3−/CO32− and some organic matter in the urine contributed to the degradation of the tetracycline. Theoretical calculations showed that CO32− in urine could be efficiently adsorbed by the introduced B atoms and converted to CO3·− by peroxydisulfate to assist the degradation of tetracycline, which was attributed to the special electronic structure of the B atoms as well as the strong electron-enrichment ability of the neighboring O atoms. The potential toxicity of tetracycline and its degradation intermediates was further explored, revealing a significant reduction in toxicity during boron-modified sewage sludge biochar/ peroxydisulfate treatment.

Influence of Surface Basic Sites and Oxygen Vacancies on the Performance of Metal-Modified Rod-Like Ceria Catalysts for Low-Temperature Hydrolysis of Carbonyl Sulfide.

This study utilized a hydrothermal method to synthesize various metal-modified rod-like ceria catalysts (Fe, Co, Cu, Ni, La), achieving efficient COS removal at low temperatures. The research identified surface oxygen vacancies and basic sites as critical factors that influence the catalytic performance of COS hydrolysis. The addition of different metals to pristine ceria rods increased the specific surface area, oxygen vacancy content (Ov), and basicity, which enhanced the catalysts' sulfur resistance and stability. Among all the catalysts tested, 10La-CeO2 demonstrated the highest COS removal rate. This is because La doping significantly augmented Ov, providing more H2O adsorption and activation sites. Furthermore, 10La-CeO2 showed enhanced Lewis basicity, making it easier for COS to adsorb and promote hydrolysis. The in situ DRIFTS results confirmed that appropriate oxygen vacancies and basic sites favored the formation of intermediates such as HCO3 - and HSCO2 -, promoting the decomposition of COS into H2S and CO2.

Ablation of premature ventricle contraction arising from papillary muscle without intracardiac echo using point-by-point mapping

Abstract Background Catheter radiofrequency ablation (RFA) of ventricular arrhythmias (VAs) arising from the left ventricle's papillary muscles (PM) has been associated with inconsistent results due to difficulties in 3D reconstruction of this intraventricular structure. The use of intracardiac echo-guided ablation allows for the 2D visualisation of the PM and the guiding of ablation catheter. Cryo energy allows stable contact with the target structure during ablation. These two techniques have been shown to increase the success rate of ablation (77% reported - 1) but don’t allow the construction of the 3D map of papillary muscle with activation during PVC. Using a combination of point-by-point mapping (PbP) along with "fast anatomical mapping" (FAM) (Carto® 3 System) allows 3D reconstruction of the PM geometry with activation. These may increase the accuracy of PVC origin targeting. Aim This study aims to assess the feasibility and success rate of RFA of PVC arising from the papillary muscles of the left ventricle. Methods and results We retrospectively analysed 214 patients treated with RFA for PVCs in two institutions. PVC arose from PM in 12(5.6%) cases (65±20 years old; 42% males; 33% with ejection fraction>50%; 8.3% antero-lateral PM). Initial detailed FAM of the left ventricle was performed using PVC pattern matching via transaortic or transmitral approach. Then, all points with preexcitation to QRS onset were copied from FAM into the new PbP map. That automatically created the geometry of PM with an activation map inside the LV shell. Irrigated high power (50 W) RFA was performed at the site of earliest activation at the PM shell. The acute success rate was 75% (n=9) without complications. PVC recurrence at 12-month follow-up was 11% (n=1 out of 9). Conclusions RFA of PVC arising from papillary muscles using point-by-point mapping is feasible and associated with a success rate comparable to the previously reported one when intracardiac echo-guided ablation is used.

Estimation of ventricular ectopic beat origin with electrocardiographic imaging

Abstract Background Precise identification of premature ventricular contractions (PVC) origins poses a significant challenge in electroanatomic mapping. Electrocardiographic Imaging (ECGI) allows instantaneous and global activation time mapping, providing a fast way to locate the origin of ectopic contractions. However, the standard methodology to estimate local activation times (LAT) in invasive electrograms is not directly transferable to ECGI signals. Objective In this study, a new methodology to calculate LAT maps with ECGI is presented and compared to the standard method in both, mathematical simulations and patients. Method We conducted computer simulations of five distinct PVCs to generate ECGI signals. Two techniques were applied to estimate LATs: the conventional -dV/dt method, which identifies the steepest negative deflection, and our novel Bayesian approach. The error in the location of the origin of the electrical activation and the similarity of the LAT maps were calculated with respect to the reference computer model. Additionally, we tested both algorithms in four patients with PVCs originated in different locations (three in the output tract of the right ventricle and one in the ventricular base, close the coronary sinus). Results The results indicated a substantial improvement in identifying the earliest activation site using our Bayesian algorithm, with a reduced localization error (1.5 ± 2.5 cm to 0.6 ± 1.5 cm). The root mean squared error (RMSE) was also significantly lower when comparing our Bayesian LAT maps to the reference LATs obtained in the simulations (19.0 ± 5.3 vs. 10.8 ± 4.5 ms). Patient data revealed smoother and more physiologically consistent propagations in the Bayesian maps, aligning with the PVC origins identified via electroanatomical navigation systems. Conclusion This study demonstrates that ECGI signals, when processed with advanced Bayesian techniques, significantly enhance LAT estimation. The proposed methodology improves the localization accuracy of ectopic beats and has practical implications for optimizing PVC treatment protocols.

Is the conventional deployment of electrode catheters appropriate to diagnose the circuit of atypical atrioventricular nodal reentrant tachycardia? -New insights into the retrograde slow pathways-

Abstract During atypical atrioventricular nodal reentrant tachycardia (AVNRT), the earliest atrial activation site following retrograde slow pathway conduction is either at the exit of the left inferior extension (LIE) in the coronary sinus (CS) or that of the right inferior extension (RIE) on the tricuspid annulus (TA). In an EP study, LIE can be detected by the CS catheter, but absence of catheters at the RIE can lead to it being missed. Aim To evaluate the electrophysiological characteristics of the retrograde slow pathway. Methods We assessed patients with atypical AVNRT using electro-anatomical 3D mapping. Results Among 14 patients (9 females, age 59±17), with a total of 18 atypical AVNRTs (15 fast/slow and 3 slow/slow), 4 patients had LIE, 6 had RIE, and 4 had both. The LIE exits were inside the CS, while those of RIE were on the posterior TA. During AVNRT or ventricular pacing, the local electrogram of RIE preceded that of the CS ostium and HBE by 24±12 and 34±12 ms respectively. Examination of activation times at the CS ostium and HBE showed that the nearer to the exit of RIE they were, the earlier they were excited. Conclusion The retrograde slow pathway of atypical AVNRT can have an exit site at the LIE or RIE, or both. Accurate identification of inferior extensions of the AV node is critical for diagnosis and treatment. We recommend placing a catheter on the posterior TA or 3D mapping the area for RIE exit detection in atypical AVNRT patients.

Imageless electrocardiographic imaging for atrial electrophysiological characterization: a validation study

Abstract Background The mechanisms responsible for atrial fibrillation (AF) are not yet fully understood and treatment strategies remain suboptimal. Electrocardiographic imaging (ECGi) could provide new insights into the arrhythmogenic substrate’s characterization. Objective To validate a novel imageless ECGi technique against electroanatomical mapping (EAM) systems to evaluate its use in guiding therapeutic decisions. Methods Periprocedural ECGi was implemented on 12 patients submitted for pulmonary vein isolation with EAM arriving in sinus rhythm. As opposed to current methods requiring patient-specific torso-heart geometries from CT/MRI scans, the employed ECGi system computes a cardiac anatomical model from a 3D-camera torso reconstruction. Both ECGi signals and intracavitary recordings were acquired simultaneously during catheter stimulation from a single atrial site at two different pacing cycles and local activation time (LAT) maps were derived. As a result, an ECGi and an EAM map were obtained for both 300 and 600 ms distal coronary sinus pacing for each patient. These were then compared by splitting the left atrial geometries from both mapping methodologies into 7 predefined, clinically relevant regions and identifying the earliest and latest activation sites in each. Results For all 24 LAT maps under consideration, the pacing sites identified by non-invasive ECGi maps were consistent with those determined through EAM as 100% accuracy was obtained in terms of detecting the first activated region. As well as the correct stimulation area, according to the corresponding EAM instance, the earliest ECGi activations were also found in one of its immediate neighbours in 38% of the maps, indicating a broader region of interest. Regarding the latest activation sites, ECGi achieved an accurate localisation in 92% of the activation sequences and, similarly, other neighbouring regions showed the maximum LAT in one third of the studied maps. Conclusions Considering the spatial resolution constraints inherent to its non-invasive nature, imageless ECGi activation patterns are congruent with the gold-standard technique for substrate mapping without the need for prior medical imaging.

GAS-Luc2 Reporter Cell Lines for Immune Checkpoint Drug Screening in Solid Tumors.

Recent studies highlight the integral role of the interferon gamma receptor (IFNγR) pathway in T cell-mediated cytotoxicity against solid but not liquid tumors. IFNγ not only directly facilitates tumor cell death by T cells but also indirectly promotes cytotoxicity via myeloid phagocytosis in the tumor microenvironment. Meanwhile, full human ex vivo immune checkpoint drug screening remains challenging. We hypothesized that an engineered gamma interferon activation site response element luciferase reporter (GAS-Luc2) can be utilized for immune checkpoint drug screening in diverse ex vivo T cell-solid tumor cell co-culture systems. We comprehensively profiled cell surface proteins in ATCC's extensive collection of human tumor and immune cell lines, identifying those with endogenously high expression of established and novel immune checkpoint molecules and binding ligands. We then engineered three GAS-Luc2 reporter tumor cell lines expressing immune checkpoints PD-L1, CD155, or B7-H3/CD276. Luciferase expression was suppressed upon relevant immune checkpoint-ligand engagement. In the presence of an immune checkpoint inhibitor, T cells released IFNγ, activating the JAK-STAT pathway in GAS-Luc2 cells, and generating a quantifiable bioluminescent signal for inhibitor evaluation. These reporter lines also detected paracrine IFNγ signaling for immune checkpoint-targeted ADCC drug screening. Further development into an artificial antigen-presenting cell line (aAPC) significantly enhanced T cell signaling for superior performance in these ex vivo immune checkpoint drug screening platforms.

Engineering Spatially Adjacent Redox Sites with Synergistic Spin Polarization Effect to Boost Photocatalytic CO2 Methanation.

The integration of oxidation and reduction half-reactions to amplify their synergy presents a considerable challenge in CO2 photoconversion. Addressing this challenge requires the construction of spatially adjacent redox sites while suppressing charge recombination at these sites. This study introduces an innovative approach that utilizes spatial synergy to enable synergistic redox reactions within atomic proximity and employs spin polarization to inhibit charge recombination. We incorporate Mn into Co3O4 as a catalyst, in which Mn sites tend to enrich holes as water activation sites, while adjacent Co sites preferentially capture electrons to activate CO2, forming a spatial synergy. The direct H transfer from H2O at Mn sites facilitates the formation of *COOH on adjacent Co sites with remarkably favorable thermodynamic energy. Notably, the incorporation of Mn induces spin polarization in the system, significantly suppressing the recombination of photogenerated charges at redox sites. This effect is further enhanced by applying an external magnetic field. By synergizing spatial synergy and spin polarization, Mn/Co3O4 exhibits a CH4 production rate of 23.4 μmol g-1 h-1 from CO2 photoreduction, showcasing a 28.8 times enhancement over Co3O4. This study first introduces spin polarization to address charge recombination issues at spatially adjacent redox sites, offering novel insights for synergistic redox photocatalytic systems.

Determination of Earthquake Depths Using Data of Cross-Sectional and Areal Deep Seismic Studies in Siberia

Abstract ––Information on the distribution of earthquake hypocenters for many seismically active zones of Siberia remains insufficient, which is associated with sparse networks of seismological observations. The paper presents the results of determining the earthquake depths in several seismogenic areas in the Altai-Sayan region, Cisbaikalia, Transbaikalia, and Yakutia using the travel time of longitudinal refracted waves from the Mohorovičič discontinuity (Pn waves) from earthquakes and the recently obtained information about the deep structure of these regions. The depth determination algorithm is tested using data from aftershocks of large earthquakes occurring in Tuva in 2011 and 2012 (ML = 6.7 and 6.8), recorded both by the regional seismological network and by a local group of seismic stations. Different methods are applied to reveal that some aftershock depths have a close match, including those for the main shocks – the Tuva-1 and Tuva-2 earthquakes. Another good match of earthquake depths is obtained using Рn waves with materials from regional and detailed studies of the Baikal branch of the Geophysical Survey of the Russian Academy of Sciences in the Muyakan activation site in the Baikal rift zone. The resulting data complement the information on the hypocenter of the main shock and confirm the change of the Muyakan activation cluster from large depths to shallow ones since the onset of activation in 2014. New information on the earthquake depths using Рn waves is obtained in Yakutia along the border of the largest Eurasian and Okhotsk tectonic plates. It is revealed that they decrease to 6–12 km as compared to higher depths of 20–30 km in adjacent areas. The resulting series of new information on the distribution of earthquake hypocenters using Рn waves is extremely important mostly because it indicates the possibility of identifying and redefining earthquake hypocenters using previous seismological observations in seismically active zones of Siberia.

Rich oxygen vacancies in core–shell structured Co3O4-CuO-ZnO@ZIF-8 for boosting CO2 hydrogenation to methanol

Converting carbon dioxide (CO2) into high-quality methanol to alleviate the energy crisis is a promising strategy. However, as a traditional catalyst for CO2 hydrogenation to methanol, Cu/ZnO exhibits low CO2 conversion and low methanol selectivity at low temperature. In order to improve the catalytic performance of CO2 hydrogenation to methanol, Co3O4 was introduced to form Co3O4-CuO-ZnO with flower-like structure, and then diamond-shaped ZIF-8 particles with large specific surface area and rich oxygen vacancies were synthesized on the surface of Co3O4-CuO-ZnO by hydrothermal method. A series of characterizations showed that the synthesis of ZIF-8 greatly increased the specific surface area of the catalyst. The oxygen vacancy is the site of CO2 adsorption and activation, and stabilizes the reaction intermediate, which promotes the conversion of CO2 and the formation of methanol. The introduction of Co promotes the formation of the alloy phase, enhances the interaction between the metals, makes the active center more dispersed, reduces the sintering of the catalyst, and thus exhibits better catalytic performance. Among co-precipitated CuO-ZnO, hydrothermal CuO-ZnO, CuO-ZnO@ZIF-8, Co3O4-CuO-ZnO and Co3O4-CuO-ZnO@ZIF-8 catalysts, Co3O4-CuO-ZnO@ZIF-8 exhibits the best catalytic performance (CO2 conversion 16.06% and CH3OH selectivity 94.58%). Based on the above design, ZIF-8 and Co3O4 synergistic CuO-ZnO catalyst effectively improved CO2 conversion and CH3OH selectivity.

Theoretical insights into the formation of oxygen activation sites with the affection of protein microenvironment in Flavin-Dependent monooxygenases MsuD

Flavin-dependent monooxygenases are very famous for their capability to catalyze the oxidation of various substrates using oxygen and reduced flavin mononucleotide (FMNH-) or reduced flavin adenine dinucleotide (FADH-). When investigating the catalytic mechanism of flavin-dependent monooxygenase systems, a fundamental problem remains unsolved is that the O2 binding scheme within the reaction cavity is unclear. By applying molecular dynamics simulations, MDpocket simulations, residue mutation molecular dynamics simulation and energy decomposition analyses, this work identified the O2 binding pockets and discovered a possible oxygen migration channel within MsuD enzyme. Molecular dynamics simulations after residue mutation proved that residues Asn104 plays an important role in maintaining the O2 position within the reaction cavity. By analyzing the interaction between O2 and the surrounding protein microenvironment, we demonstrated that N5 is a more favored reaction site and speculated a reasonable O2 activation process. This work recovers the formation of oxygen activation sites in MsuD enzyme, which is of great significance to further investigations of the catalytic reaction mechanism. This work provides a feasible method to study the O2 binding in proteins and the role of the protein microenvironment around the reaction cavity.

Novel insights into ferrate (VI) activation by Mn-modified sludge biochar for sulfamethoxazole degradation: Dominance of hydroxyl group and Mn-O bond in the non-radical pathway

Ferrate (Fe (VI)), as a versatile oxidizer, has been widely employed for water treatment. However, the rapid self-decomposition of Fe (VI) diminishes its practical application efficiency. In this study, a novel Mn-modified sludge biochar (MSBC) was synthesized for the first time to activate Fe (VI) and generate highly reactive Fe (IV)/Fe (V) for the rapid removal of sulfamethoxazole (SMX). The results showed that MSBC (0.10 g/L) effectively activated Fe (VI) (100 μM), and 87.39 % of SMX (10 μM) and 40.26 % of total organic carbon (TOC) were removed within 10 min. Notably, raising the solution pH (e.g., from 6.0 to 11.0) would result in decreasing the reactivity of Fe (VI) and a lower removal efficiency of SMX. The quenching, electron paramagnetic resonance and probe experiments suggested that •O2– and high-valent iron species (Fe (V)/Fe (IV)) were identified as the major contributions to the removal of SMX. The detailed activation sites of MSBC were –OH and Mn-O, as corroborated by density functional theory (DFT) calculation and characterization. These activation sites facilitated activation of Fe (VI) through efficient electron transfer. The Fukui index indicated that the N, S, and O atom of SMX were the primary attacked sites. Subsequently, five potential degradation pathways were proposed, with the cleavage of the S-N bond being the predominant one. The toxicity of these products was examined using ECOSAR program, revealing that main products showed low toxicity or non-toxicity. The Cl-, SO42-, and NO3– had negligible effect on SMX degradation, although excessive concentrations of HCO3– and humic acid (HA) showed slightly inhibition. Additionally, the Fe (VI)/MSBC system also effectively removed 87.34 % of sulfadiazine (SDZ) and 93.91 % of sulfamethoxypyridazine (SMP). Overall, this study offered a practical and cost-effective approach for the activation of Fe (VI) and provided new insights to the degradation mechanism.

Instilling liveliness: archives of neo-avant-garde art as sites of activation

Artists’ archives, typically a legacy trove rather than a site for public engagement, are not expected to encompass art. However, since the mid-twentieth century, factors like the ‘dematerialisation of art’, defiance against conventional art categorisations, and the prioritisation of the creative process over its outcomes, have all blurred the lines between artworks and their documentation. Consequently, a significant portion of art produced during the 1960s and 1970s still resides in archives, distributed in art objects and documents. By examining the archives of Ecart, an artistic collective that operated within the broader Fluxus network in 1970s Switzerland, this study proposes activation as an alternative strategy for caring for and securing the continuation of such art, which is often found scattered across various archival holdings. Ultimately, the research suggests activation as a way of expanding conservation beyond the exclusive domain of trained conservators, transforming it into a collective responsibility shared by diverse archive stakeholders.

Experimental and theoretical studies on the photoelectrocatalytic property of titanium dioxide nanoarrays improved by S,N co-doped graphene quantum dots

In this paper, sulfur and nitrogen co-doped graphene quantum dots (S,N-GQDs) were compounded with titanium dioxide (TiO2) nanorods by chemical surface modification. S,N-GQDs in diameter of 5 nm are uniformly distributed on the surface of TiO2 nanorod arrays. The presence of CS bonds in S,N-GQDs not only broaden the absorption of visible light by GQDs, but also enhanced the visible light absorption of S,N-GQDs/TiO2 composites. The photocurrent densities of S,N-GQDs/TiO2 were 3.66 times that of unmodified TiO2. The calculation results of density functional theory (DFT) showed that the band gap of S,N-GQDs is significantly reduced compared to GQDs, indicating that electrons are more likely to transit to higher energy levels and form more activation sites. Moreover, compared with TiO2, the DFT calculation results of band gap, density of states and charge density difference of S,N-GQDs/TiO2 showed that S,N-GQDs/TiO2 had a wide wavelength of visible light absorption and better electron-hole separation ability, resulting in the superior photoelectrocatalytic property. This research provides favorable analytical value for the development of photocatalysts based on heterostructures.