Primary Active Site Research Articles

Sustainable activation of peroxymonosulfate by the Mo(IV) in MoS2 for the remediation of aromatic organic pollutants

Although MoS2 has been proved to be a very ideal cocatalyst in advanced oxidation process (AOPs), the activation process of peroxymonosulfate (PMS) is still inseparable from metal ions which inevitably brings the risk of secondary pollution and it is not conducive to large-scale industrial application. In this study, the commercial MoS2, as a durable and efficient catalyst, was used for directly activating PMS to degrade aromatic organic pollutant. The commercial MoS2/PMS catalytic system demonstrated excellent removal efficiency of phenol and the total organic carbon (TOC) residual rate reach to 25%. The degradation rate was significantly reduced if the used MoS2 was directly carried out the next cycle experiment without any post-treatment. Interestingly, the commercial MoS2 after post-treated with H2O2 can exhibit good stability and recyclability for cyclic degradation of phenol. Furthermore, the mechanism for the activation of PMS had been investigated by density functional theory (DFT) calculation. The renewable Mo4+ exposed on the surface of MoS2 was deduced as the primary active site, which realized the direct activation of PMS and avoided secondary pollution. Taking into account the reaction cost and efficient activity, the development of commercial MoS2 catalytic system is expected to be applied in industrial wastewater.

Insight into the mechanism of persulfate activated by bone char: Unraveling the role of functional structure of biochar

Recently, biochar was frequently applied in catalysis field, and it has been regarded as an efficient carbon-rich material to degrade organic pollutants in water. Various functional structures of biochar (such as pore structure, oxygen-containing groups and, defects) have been reported to be valid in catalysis. Whereas the complexity of biochar structure and composition hinders the further exploration of specific functions of biochar. To address this problem, selective inactivation experiment was first involved to investigate the role of oxygen-containing groups in catalysis. In this study, swine bone derived biochar (BBC) was adopt as catalyst in persulfate (PS) activation system to degrade acetaminophen (ACT). Both non-radical and radical pathway worked in BBC/PS system. ACT could be completely degraded in 60 min, and the removal rate could reach 0.3111 min−1. The results showed that the ketone groups on the BBC were the primary active sites of PS/BBC system and it played a major role in non-radical pathway (electron transfer pathway), and it might act as the active sites to produce OH in BBC/PS system. Besides, the COOH and OH on BBC might be beneficial to radical pathway, which can help to generate OH and SO4−. Interestingly, residual hydroxyapatite and defects in BBC might be able to stimulate PS to produce O2− and 1O2. With the development of increasingly precise biochar synthesis techniques, these verdicts give evidence to further oriented synthesis of biochar.

Upcycling coal liquefaction residue into sulfur-rich activated carbon for efficient Hg0 removal from coal-fired flue gas

Recent, carbon-based adsorption technology, especially activated carbon with element-doping treatment, has been considered an effective approach to capture elemental mercury (Hg0) from coal-fired flue gas. In this study, a novel sulfur-rich activated carbon (S/AC) was in-situ derived from coal liquefaction residue (CLR) with KOH activation, which can make full use of the sulfur in CLR and simplify the preparation process. The effects of KOH to CLR weight ratios and activation temperatures on Hg0 removal performance were discussed. The S/AC was characterized by N2 adsorption/desorption, XRD, SEM, TEM-EDS, XPS and Hg-TPD techniques. A fixed-bed reactor was used to estimate the Hg0 removal performance of sorbents. The effects of adsorption temperatures and flue gas components on Hg0 removal performance were also evaluated. The sorbent exhibited excellent Hg0 removal performance with the KOH to CLR weight ratio of 1:2 and the activation temperature of 800 °C. The Hg0 removal efficiency was stabilized at 97% at 60–120 °C with a gas hourly space velocity (GHSV) of 7.5 × 104 h−1. Both SO2 and NO exhibited positive influences on S/AC sorbents for Hg0 capture. The XPS and Hg-TPD results indicated that sulfur is primary active site for Hg0 removal, and the mercury adsorbed on S/AC sorbent was HgS. The research indicated that CLR is a potential raw material for synthesizing high efficient S/AC sorbents for Hg0 removal from flue gas.

Metal-free carbocatalysis for persulfate activation toward nonradical oxidation: Enhanced singlet oxygen generation based on active sites and electronic property

In recent years, metal-free carbocatalysis and persulfate-based advanced oxidation processes have appealed much attention due to the high efficiency and environmental sustainability. This study aimed to investigate catalytic performance of carbon nanofibers (CNFs) on persulfate for removal of 2,4-dichlorophenol and elucidate the intrinsic mechanism of PS activation. Singlet oxygen (1O2) generation was hypothesized to be the dominant pathway for the nonradical organic oxidation. Carbonyl groups and structural defects were determined as the primary active sites via CNFs modification. Density functional theory (DFT) calculations further unearthed that armchair and zigzag edges were favorable to electron transfer and vacancy sites enhanced PS adsorption on CNFs. A higher density of states (DOS) with lower π and σ electronic binding energies would make CNFs more active, and a lower work function (Ф) would lead to a lower inner electron excitation energy barrier to enhance the electron transfer. The degradation pathways were finally determined by combining mass spectrum analysis and DFT calculations (Fukui function), where 1O2 molecules were likely to attack the Cl and O atoms.

Peroxymonosulfate activated with waste battery-based Mn-Fe oxides for pollutant removal: Electron transfer mechanism, selective oxidation and LFER analysis

Mn2O3-Fe2O3 catalyst was fabricated from spent alkaline batteries and used for effective elimination of acetaminophen (APAP) by activating peroxymonosulfate (PMS). APAP removal at various initial pH, its degradation pathway and the stability of catalyst were investigated. The Mn(III) was inferred to be the primary active site and Fe(III) could improve the corrosion resistance through intermetallic interactions. Chemical quenching experiments, electron paramagnetic resonance (EPR) spectroscopy, solvent exchange, open circuit potential (OCP) and chronoamperometry tests imply that APAP is oxidized by electron transfer through highly reactive surface-adsorbed PMS. Fourier transform infrared (FTIR), in situ Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) spectra and ionic strength experiments further revealed the interaction between the catalyst and PMS. The Mn2O3-Fe2O3/PMS system exhibits selective oxidation for different contaminants, and linear free energy relationship (LFER) was employed to investigate the effect of structure and properties of pollutant on the reaction kinetics. Pollutant with peak potential (Eop) > 0.91 V, the steady-state OCP in the Mn2O3-Fe2O3/PMS system, is resistant to oxidation; while pollutant with Eop < 0.91 V is prone to be oxidized and there is a good correlation between apparent first-order rate constant (k1) and Eop. The research not only puts in-depth study into PMS activation through environment-friendly Mn-Fe oxides from spent alkaline batteries, but also provides some new insights for nonradical mechanism, selective oxidation and LFER study.

Direct production of 2,5-diformylfuran from fructose catalysed by Mo-based composite oxides in static air

A series of MxMoyOδ composite oxides (M = Ca, Mn, Fe, Co, Ni, Cu, Zn, Y, Bi, Zr, La or Ce) was synthesized and used for the one-pot direct conversion of fructose to 2,5-diformylfuran (DFF) using atmospheric air as the oxidant. Among these materials, ZrxMoyOδ exhibited the best catalytic performance. Hence, the effects of the Zr/Mo molar ratio and calcination temperature on catalytic performance were investigated in detail and the reaction conditions were also optimized. The highest performing catalyst, Zr1Mo2Oδ, produced a DFF yield of 61 % along with the complete conversion of fructose under the optimized reaction conditions. More importantly, this material also exhibited good recycling stability and could be reused five times without a noticeable loss of activity. These ZrxMoyOδ catalysts were characterized using multiple techniques. Zirconium oxide was found to interact strongly with molybdenum oxide species via the formation of Zr(MoO4)2, thus producing a large number of surface chemisorbed oxygen species. The close linear correlation between DFF yield and surface chemisorbed oxygen confirmed that these oxygen species were the primary active sites for the oxidation reaction.

Citric acid-modified beta zeolite for polyoxymethylene dimethyl ethers synthesis: The textural and acidic properties regulation

Beta zeolite exhibits satisfactory catalytic activity in the synthesis of polyoxymethylene dimethyl ethers. However, the microporous channels of beta zeolite have adverse effects on mass transfer of macromolecules. In this work, it was found that the textural and acidic properties of catalysts could be improved by citric acid treatment. Extensive characterization confirmed that citric acid induced significant pore-expanding on catalysts, and its dealumination and realumination effect could lead to reduced amount of total acid sites and increased amount of Brønsted acid sites (BAS). Meanwhile, a good positive correlation was found between amount of external weak BAS and initial reaction rate. It was speculated that BAS with relatively weak acid strength might be the primary active sites in this reaction. Compared with the blank sample, the initial reaction rate of optimal catalyst was increased by 100 %, and the conversion of trioxane was increased by 86.5 %, indicating a significantly improved catalytic activity.

Adsorption of Pb2+ and Cu2+ ions on the CS2-modified alkaline lignin

A kind of alkaline lignin (AL)-based modified material (FLAL) was fabricated, in which CS2 was selected as the modifier. FLAL can be used to treat Pb2+ and Cu2+ ions loaded water. When the initial concentrations of Pb2+ and Cu2+ ions were 30 mg/L, the removal efficiencies were 97% for Pb2+ at 100 min while 98% for Cu2+ at 5 min, respectively. The maximum adsorption capacities (qm) of Pb2+ and Cu2+ ions were 0.322 and 1.010 mmol/g, indicating that the adsorption capacity of FLAL for Cu2+ ions was better than for Pb2+ ions. The groups of hydroxyl, methoxyl and dithiocarbamate carried by FLAL contributed to binding with Pb2+/Cu2+ ions. Dithiocarbamate (CSS) was proved to be the primary active site, in which the binding energy (Ead) of SCuS and SPbS were −1.1739 and −0.8709 Ha. These results suggest the interaction between FLAL and Cu2+ ions was stronger and FLAL-Cu2+ complexes were more stable, revealing the reason why the uptake of Cu2+ ions by FLAL was quicker in speed and larger in amount. The reusing ability of FLAL was evaluated through a four-adsorption–desorption cycle. The values of qm for Pb2+ and Cu2+ ions were 0.258 and 0.878 mmol/g corresponding to the fourth regeneration, decreased by 19.87% and 13.06% compared to fresh FLAL. The adsorption performance of both fresh and regenerated FLAL is better than many other biomass-based adsorbents. FLAL can be regarded as a promising material with high application potential, which warrants future studies on optimizing FLAL for real-world applications.

Hafnium-Doped Mesoporous Silica as Efficient Lewis Acidic Catalyst for Friedel-Crafts Alkylation Reactions.

The development of an efficient solid catalyst for Friedel–Crafts (FC) reactions is of great importance to organic synthetic chemistry. Herein, we reported the hafnium-doped mesoporous silica catalyst Hf/SBA-15 and its first use for Friedel–Crafts alkylation reactions. Catalysts with different Si/Hf ratios were prepared and characterized, among which Hf/SBA-15(20) (Si/Hf = 20:1) was the most active catalyst, offering up to 99.1% benzylated product under mild reaction conditions. The influences of reaction conditions on the product were systematically investigated and compared. Pyridine-IR characterization of the catalyst showed that Lewis acid formed the primary active sites for the Friedel–Crafts alkylation reaction. X-ray photoelectron spectroscopy (XPS) characterization revealed that the electron shift from the Hf center to the silica framework resulted in a more active Lewis metal center for FC reactions. Moreover, the catalyst was successfully applied to the alkylation reaction with different alcohols and aromatic compounds. Finally, the Hf/SBA-15(20) catalyst also showed good recyclability in the recycling runs, demonstrating its high potential of being used for large scale FC reactions in the industry.

Picomolar to Micromolar: Elucidating the Role of Distal Mutations in HIV-1 Protease in Conferring Drug Resistance.

Drug resistance continues to be a growing global problem. The efficacy of small molecule inhibitors is threatened by pools of genetic diversity in all systems, including antibacterials, antifungals, cancer therapeutics, and antivirals. Resistant variants often include combinations of active site mutations and distal "secondary" mutations, which are thought to compensate for losses in enzymatic activity. HIV-1 protease is the ideal model system to investigate these combinations and underlying molecular mechanisms of resistance. Darunavir (DRV) binds wild-type (WT) HIV-1 protease with a potency of <5 pM, but we have identified a protease variant that loses potency to DRV 150 000-fold, with 11 mutations in and outside the active site. To elucidate the roles of these mutations in DRV resistance, we used a multidisciplinary approach, combining enzymatic assays, crystallography, and molecular dynamics simulations. Analysis of protease variants with 1, 2, 4, 8, 9, 10, and 11 mutations showed that the primary active site mutations caused ∼50-fold loss in potency (2 mutations), while distal mutations outside the active site further decreased DRV potency from 13 nM (8 mutations) to 0.76 μM (11 mutations). Crystal structures and simulations revealed that distal mutations induce subtle changes that are dynamically propagated through the protease. Our results reveal that changes remote from the active site directly and dramatically impact the potency of the inhibitor. Moreover, we find interdependent effects of mutations in conferring high levels of resistance. These mechanisms of resistance are likely applicable to many other quickly evolving drug targets, and the insights may have implications for the design of more robust inhibitors.

Continuous Partial Oxidation of Methane to Methanol Catalyzed by Diffusion-Paired Copper Dimers in Copper-Exchanged Zeolites.

Copper-exchanged zeolites can continuously and selectively catalyze the partial oxidation of methane to methanol using only oxygen and water at low temperatures, but the genesis and nature of the active sites are currently unknown. Herein, we demonstrate that this reaction is catalyzed by a [Cu-O-Cu]2+ motif that forms via a hypothesized proton-aided diffusion of hydrated Cu ions within the cages of SSZ-13 zeolites. While various Cu configurations may be present and active for methane oxidation, a dimeric Cu motif is the primary active site for selective partial methane oxidation. Mechanistically, CH4 activation proceeds via rate-determining C-H scission to form a surface-bound C1 intermediate that can either be desorbed as methanol in the presence of H2O/H+ or completely oxidized to CO2 by gas-phase O2. High partial oxidation selectivity can be obtained with (i) high methane and water partial pressures and (ii) maximizing Cu dimer formation by using zeolites with high Al content and low Cu loadings.

Carbon-Nanotube-Appended PAMAM Dendrimers Bearing Iron(II) α-Keto Acid Complexes: Catalytic Non-Heme Oxygenase Models.

Poly(amidoamine) dendrimers grafted on carbon nanotubes have been appended with iron(II)-α-keto acid (benzoylformate) complex of polypyridyl ligand to design artificial non-heme oxygenase model. This nano-enzyme was applied for selective catalytic oxidation of organic molecules. Although the carbon nanotubes serve as a robust heterogeneous platform, the amine terminals of dendrimers provide catalysts binding sites and the amide bonds provide a necessary second coordination sphere similar to the enzymatic polypeptide chains. Such a hybrid design prevented the deactivation of the primary active sites leading to 8 times faster oxidative decarboxylation rates than those of its homogeneous analogue. An electrophilic iron(IV)-oxo intermediate has been intercepted, which catalyzes the selective oxidation of alcohols to aldehydes and incorporates single oxygen atoms into sulfides and olefins by using aerial oxygen with multiple turnover numbers. The catalyst was consecutively regenerated three times by mild chemical treatment and showed negligible loss of activity.

Increasing the electrochemical activity of basal plane sites in porous 3D edge rich MoS2 thin films for the hydrogen evolution reaction

Molybdenum disulfide (MoS2) has been extensively utilized as an electrocatalyst for the hydrogen evolution reaction (HER) with edges as the primary active catalytic sites. Previous work on edge-rich MoS2 nanoplatelet 3D porous films (3D-ER-MoS2) shows they are promising catalysts, yet have basal planes that are inactive. Here we demonstrate how hydrogen annealing and oxygen plasma etching of 3D-ER-MoS2 generates defects and increases active site density within the basal plane, leading to dramatic improvements in HER catalytic activity. We also explore the critical processing parameters for electrocatalytic enhancement. Significantly enriched edge density was revealed for both routes. O2 plasma treatment was more effective in increasing the number of edges by creating micro-cracks and local surface damage on the basal planes as well as structuring saw-toothed edges; H2 etching mainly introduced irregular shaped basal surface nanopores and strips. By controlling processing parameters, optimum surface area/active sites density enhancement can be achieved, together with the robust 3D porous architecture and superaerophobic surface. The defect-rich MoS2 catalysts exhibit excellent HER activity: 700 °C – H2 – MoS2 shows Tafel slope of 94 mV/dec and low onset overpotential of 193 mV; 15 min – O2 – MoS2 performs amongst the best with excellent exchange current density of 57 μA/cmgeo−2. Our defect engineered 3D-ER MoS2 exhibits jgeo (η = 0.5 mV) of 6-fold and 38-fold compared to monolayer MoS2 subject to similar process, for O2 plasma and H2 etching approaches respectively. Our study demonstrates an effective way to realize high performance Pt-free electrocatalysts for hydrogen generation by dual enhancement via edge enrichment and basal surface activation.

Development of Fe-doped g-C3N4/graphite mediated peroxymonosulfate activation for degradation of aromatic pollutants via nonradical pathway

A new composite catalyst, i.e., Fe doped g-C3N4/graphite (Fe-CN/G), was successfully constructed to activate peroxymonosulfate (PMS) for efficient phenolic compounds (i.e., p-chlorophenol, 4-CP) degradation in the pH range of 3–10. The optimized Fe-CN/G, i.e., Fe3.75-CN/G5.0, was fabricated at the dosage of 3.75 mmol FeCl3·6H2O, 5.0 g dicyandiamide, and 5.0 mmol glucose. Fe complexed in the nitrogen pots of Fe3.75-CN/G5.0 was demonstrated to be the primary active site for PMS activation, and the introduction of graphite favored the exposure of more accessible active sites in Fe3.75-CN/G5.0, suggesting a synergistic effect between the Fe and graphite of Fe3.75-CN/G5.0 on 4-CP degradation. Multiple experiments confirmed that sulfate radical (SO4−), hydroxyl radical (HO), singlet oxygen (1O2) and superoxide radical (O2−) exerted negligible contribution on 4-CP degradation. The in-situ Fe K-edge X-ray absorption near-edge structure (XANEX) analysis revealed a redox cycle of Fe in PMS/Fe3.75-CN/G5.0, suggesting the formation of high-valent iron-oxo species (FeIVO) was responsible for 4-CP degradation. In addition, PMS/Fe3.75-CN/G5.0 exhibited acceptable degradation of 4-CP in the presence of coexisting anions and natural organic matters (NOM). We believe this study provides new insights into the design and development of Fe-based heterogeneous catalysts for PMS-based wastewater treatment.

PM to μM: Elucidating the Interdependence of Highly Resistant HIV‐1 Proteases

HIV‐1 protease is an ideal model system to investigate the molecular mechanisms of resistance against small molecule inhibitors. Darunavir (DRV) binds WT HIV‐1 protease with a potency of &lt;5 pM. We have identified a protease variant that loses potency to DRV 150,000‐fold, with 11 mutations in and outside the active site. Traditionally, active site mutations were thought to confer resistance while other “secondary” mutations compensate for losses in enzymatic activity. To elucidate the molecular mechanisms and roles of these selected mutations in DRV resistance, we used a multidisciplinary approach, combining enzymatic assays, crystallography, and molecular dynamics simulations. Analysis of protease variants with 1, 2, 4, 8, 9, 10 and 11 mutations showed that the primary active site mutations caused ~50‐fold loss in potency (2 mutations), while distal mutations outside the active site further decreased DRV potency from 13 nM (8 mutations) to 760 nM (11 mutations). Structural analysis indicates distal mutations induce subtle changes that are dynamically propagated through the protease. Our results reveal that many of the changes remote from the active site directly and dramatically impact the potency of the inhibitor. These mechanisms of resistance are likely applicable to many other quickly evolving drug targets and these insights have implications for the design of more robust inhibitors.Support or Funding InformationThis work was supported in part by a grant from the National Institute of General Medical Sciences, National Institutes of Health (P01‐GM109767)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Nanocarbon-based catalysts for esterification: Effect of carbon dimensionality and synergistic effect of the surface functional groups

Carbon-based solid acid catalysts represented outstanding hydrothermal and mechanical properties but lower catalytic performances and stabilities. Therefore, more comprehensive investigations should be conducted to optimize their catalytic performances. The correlations between catalytic performance, carbon dimensionality and composition of oxygen-containing functional groups of nanocarbon-based catalysts were investigated. The dimensionality of carbon materials had notable effect on the catalytic reactivity and the layered 2-D structure could maximize the solid/liquid interface and minimize the mass transfer resistance and thus favor the catalytic esterification. GO-50, prepared with 50 mL concentrated H2SO4, exhibited outstanding catalytic activity and had 3 times higher turnover frequency (TOF) value than that of H2SO4. In GO-50, the -SO3H groups were identified as the primary catalytic active sites, while the carboxyl groups enhanced the inherent activity of -SO3H, thus facilitating the esterification. The -COOH/-SO3H molar ratio played significant roles and desirable -COOH/-SO3H molar ratio would promote esterification significantly. The esterification kinetics catalyzed by GO-50 was studied and the apparent activation energy of esterification by GO-50 is 1.5 times lower than that by H2SO4. The esterification mechanism by GO-50 was also proposed. Furthermore, GO-50/Poly (ether sulfones) (PES) membrane was prepared and employed in esterification and the optimal reaction conditions were systematically studied.

Shear Stress Ameliorates Superoxide Impairment to Erythrocyte Deformability With Concurrent Nitric Oxide Synthase Activation.

The cellular deformability of red blood cells (RBC) is exceptional among mammalian cells and facilitates nutrient delivery throughout the microcirculation; however, this physical property is negatively impacted by oxidative stress. It remains unresolved whether the molecular determinants of cellular deformability – which in the contemporary model of RBC are increasingly recognized – are sensitive to free radicals. Moreover, given cellular deformability has recently been demonstrated to increase following exposure to specific doses of mechanical stimulation, the potential for using shear “conditioning” as a novel method to reverse free-radical induced impairment of cell mechanics is of interest. We thus designed a series of experiments that explored the effects of intracellular superoxide (O2-) generation on the deformability of RBC and also activation of pivotal molecular pathways known to regulate cell mechanics – i.e., PI3K/Akt kinase and RBC nitric oxide synthase (NOS). In addition, RBC exposed to O2- were conditioned with specific shear stresses, prior to evaluation of cellular deformability and activation of PI3K/Akt kinase and RBC-NOS. Intracellular generation of O2- decreased phosphorylation of RBC-NOS at its primary activation site (Ser1177) (p < 0.001), while phosphorylation of Akt kinase at its active residue (Ser473) was also diminished (p < 0.001). Inactivation of these enzymes following O2- exposure occurred in tandem with decreased RBC deformability. Shear conditioning significantly improved cellular deformability, even in RBC previously exposed to O2-. The improvement in cellular deformability may have been the result of enhanced molecular signaling, given RBC-NOS phosphorylation in RBC exposed to O2- was restored following shear conditioning. Impaired RBC deformability induced by intracellular O2- may be due, in part, to impaired activation of PI3K/Akt, and downstream signaling with RBC-NOS. These findings may shed light on improved circulatory health with targeted promotion of blood flow (e.g., exercise training), and may prove fruitful in future development of blood-contacting devices.

SnS4]4- clusters modified MgAl-LDH composites for mercury ions removal from acid wastewater

The high acidity of mercury ions (Hg2+) contained wastewater can complicate its safe disposal. MgAl-LDHs supported [SnS4]4- clusters were synthesized for Hg2+ removal from acid wastewater. The active sites of [SnS4]4- clusters were inserted into the interlayers of MgAl-LDHs using an ion-exchange method. The experimental results indicated that [SnS4]4−/MgAl-LDHs composite can obtain higher than 99% Hg2+ removal efficiency under low pH values. The maximum mercury adsorption capacity is 360.6 mg g−1. It indicated that [SnS4]4- clusters were the primary active sites for mercury uptake, existing as stable Hg2(SnS4) on the surface of the composite. Under low pH values, such a composite seems like a “net” for HgSO4 molecules, exhibiting great potential for mercury removal from acid solutions. Moreover, the co-exist metal ions such as Zn2+, Na+, Cd2+, Cr3+, Pb2+, Co2+, and Ni2+ have no significant influences on Hg2+ removal. The adsorption isotherms and kinetics were also studied, indicating that the adsorption mechanism follows a monolayer chemical adsorption model. The [SnS4]4−/MgAl-LDHs composite exhibits a great potential for Hg2+ removal from acid wastewater.

Computing neurite outgrowth and arborization in superior cervical ganglion neurons

Dendrites are the primary site of synaptic activity in neurons and changes in synapses are often the first pathological stage in neurodegenerative diseases. Molecular studies of these changes rely on morphological analysis of the imaging of somas and dendritic arbors of cultured or primary neurons. As research on preventing or reversing synaptic degeneration develops, demands increase for user-friendly 2D neurite analyzers without undermining accuracy and reproducibility. The most common method of 2D neurite analysis is manual by using ImageJ. This method relies completely on the user’s ability to distinguish the shape and size of dendrites and trace morphology with a series of straight connected lines. Semi-automatic methods have also been developed, such as the NeuronJ plugin for ImageJ. These methods still rely on the user to identify the start and end of the dendrites, but automatically determine the shape, reducing the likelihood of user bias and speeding the process. Some automatic methods have been developed through image processing software, like ImagePro. These programs tend to be expensive, but have been shown to be fast and effective, limiting user interaction. In this study, we compare three methods of neurite analysis—ImageJ, NeuronJ, and ImagePro—in measuring the soma size, number of dendrites, and length of dendrites per cell of embryonic sympathetic rat neurons with BMP-7-induced dendritic growth. Our results indicate that ImageJ and NeuronJ measurements were of similar effectiveness and consistent throughout various images and multiple trials. NeuronJ required less user interaction in measuring the length of dendrites than the manual method and therefore, was faster and less labor intensive. Conversely, ImagePro tended to be inconsistent across images, overestimating both soma size and the number of dendrites per cell while underestimating the length of dendrites. Overall, NeuronJ, in conjunction with ImageJ, is the most reliable and efficient method of 2D neurite analysis tested in the present study.

Metal–organic framework‐derived cobalt and nitrogen co‐doped porous carbon with four‐coordinated Co–Nx for efficient acetylene hydrochlorination

Industrial production of vinyl chloride through acetylene hydrochlorination is a dominating technique in coal‐rich areas, but its development is severely restricted by the use of toxic mercury chloride (HgCl2) catalyst. Inspired by the fact that doped carbon materials active in acetylene hydrochlorination often have good performance in the oxygen reduction reaction, a series of cobalt and nitrogen co‐doped porous carbon catalysts prepared by pyrolysis of bimetallic ZIFs based on ZIF‐8 and ZIF‐67 under N2 were applied in acetylene hydrochlorination. The catalytic activities of the co‐doped catalysts varied with Co addition, and the highest acetylene conversion could be up to 83% with a space velocity of 2.6 ml g−1 min−1 at 220°C when a small amount of cobalt was introduced. Results of several characterizations confirmed the existence of Co–Nx in the co‐doped carbons, pointing out that this coordination structure makes the catalysts have better ability to adsorb and activate C2H2. Density functional theory calculation finally proved that C atom adjacent to the N atom in Co–N4 structure is the primary active site in co‐doped catalysts with high activity. We also conclude that the decreased N content caused by Co2N decomposition and the coordination structure change of Co–Nx should be responsible for the gradually worsening performances of the carbon catalysts with further Co addition. Our study provides a new route for improving the performance of N‐doped carbon material in acetylene hydrochlorination and thus enhances its potential for practical application.