Reactive Carbon Research Articles

Structure and mechanical properties of reactive and non-reactive sputter deposited WC based coatings

During the growth of WC based thin films, carbon can be introduced by either a non-reactive or reactive deposition route. In this study, we compare the influence of the carbon origin on the coating properties, sputtering three different target materials – a ceramic WC, a ceramic WC including a conventional cobalt binder, and a metallic tungsten (W) target – in reactive (acetylene, C2H2) as well as non-reactive (pure Ar) atmospheres. The morphology changes, independently to the target type and atmosphere used, from crystalline (hex-W2C rich to pure fcc-WCx) to a nanocomposite (fcc-WCx nanometre sized grains embedded in an amorphous matrix) structure, up to amorphous coatings, only dominated by the prevalent C/W ratio. The cobalt binder however leads to a preferred amorphization of the coatings. The highest hardness is obtained for predominantly fcc structured WC0.67 (WC ceramic target), H = 40 ± 1.7 GPa, exhibiting also an excellent intrinsic fracture toughness of KIC = 3.3 ± 0.33 MPa·m1/2 obtained by micro-mechanical testing. Furthermore, the bonding nature of carbon is distinctly affected by the reactive carbon source, leading to more pronounced π-bonded carbon peak with increasing C2H2/Ar flow rates.

Filtration and structure of bentonite-β-cyclodextrin polymer microspheres suspensions: Effect of thermal aging time

Effective filtration loss control is a challenge for water-based drilling fluid when drilling high temperature and high pressure (HTHP) formations. After thermal aging at 200 °C for varying times, the static filtration loss controlling capabilities of β-cyclodextrin polymer microspheres (β-CDPs) and synthetic polymer Driscal-D in bentonite suspensions were compared in this study. A comprehensive physicochemical characterization was presented using Fourier transform infrared (FT-IR), X-ray diffraction (XRD), particle size distribution, zeta potential, electrical conductivity and scanning electron microscope (SEM). The results indicated that when exposure to thermal aging of 200 °C, the filtration loss of bentonite suspension increased with the initial 6 h of aging, after that it increased slightly. While for synthetic polymer Driscal-D, the filtration loss increased gradually with thermal aging time until to 36 h. In contrast for β-CDPs, the filtration loss increased firstly and then decreased and maintained relatively stable after thermal treatment for 6 h. High temperature destroyed the hydrated structure of bentonite particles and induced the increase of filtration loss volume. In viewing of Driscal-D, degradation of the polymer in combination with dehydration of bentonite particles led to the gradual losing of suspensions stability. For β-CDPs, after aging of 6 h, the hydrothermal carbonization reaction generated numerous nano and micro carbon spheres and bentonite-carbon sphere composited structures, which fill in the gaps between the larger particles and contribute to reducing the filter cake permeability. This result identified that β-CDPs are superior to synthetic polymer Driscal-D in filtration control when subjected to long term high temperature environments.

Preparation and high-performance lithium storage of intimately coupled MnO2 nanosheets@carbon nanotube-in-nanotube

MnO2 nanosheets@carbon nanotube-in-nanotube is rationally constructed through carbonization of tannic acid-treated zeolitic imidazolate framework-8 string of carbon nanotubes and subsequent chemical reaction of KMnO4 and carbon. The ultrathin MnO2 nanosheets are intimately coupled on the surface of carbon nanotube-in-nanotube. The composite shows large specific surface area (126.6 m2 g−1) and pore volume (0.4 cm3 g−1). Comparative studies of cyclic voltammetry curves and galvanostatic charge-discharge profiles indicate that for MnO2 nanosheets@carbon nanotube-in-nanotube, electrochemical activities and charge-discharge capabilities of MnO2 and carbon are both significantly improved. The cycling measurements reveal that the composite shows much higher reversible capacity and cycling stability than pure MnO2, carbon nanotubes, carbon nanotube-in-nanotube and MnO2 nanosheets@carbon nanotubes. The superior Li storage performance is attributed to synergistic effect of MnO2 nanosheets and carbon nanotube-in-nanotube. The ultrathin nanosheet structure of MnO2 and the unique nanotube-in-nanotube structure of carbon remarkably shorten diffusion paths of Li ions, facilitate transport of electrolyte ions, promote contact between electrode material/electrolyte, improve structural stability of the composite, increase electronic conductivity of MnO2, enhance reaction kinetics.

Monodispersed Ni active sites anchored on N-doped porous carbon nanosheets as high-efficiency electrocatalyst for hydrogen peroxide sensing

Metal active species combined with N-doped porous carbon nanosheets usually own excellent electrochemical activity and sensing performance owing to its unique microstructure and composition. In this work, monodispersed Ni active sites anchored on N-doped porous carbon nanosheets (Ni@N–PCN) were facilely prepared via rational metal-organic frameworks (MOFs) route. Firstly, zeolitic imidazolate frameworks-8 (ZIF-8) was in situ grown on physically-exfoliated graphene nanosheets (GN) with homogeneous sandwich-like structure (ZIF-8@GN). Secondly, nickel bonded ZIF-8@GN hybrids (Ni/ZIF-8@GN) were obtained by ionic exchange reaction, and then transformed into Ni@N–PCN by high-temperature pyrolysis. Benefiting from the monodispersed Ni active sites and highly reactive N-doped porous carbon nanosheets (N–PCN), the as-prepared Ni@N–PCN hybrids displayed superior catalytic performance toward hydrogen peroxide (H2O2) sensing. As a result, a highly sensitive electrochemical sensing platform for H2O2 was fabricated with low detection limit (0.032 μM), wide detection linearity (0.2–2332.8 μM), and high sensitivity (6085 μA cm−2 mM−1). Besides, the as-developed electrochemical sensing platform was successfully applied to detect H2O2 contents in biological medicine and food specimens with satisfied results. This study will provide effective guidance for the preparation of novel metal/N-doped carbon nanomaterials and establishment of high-performance electrochemical sensors.

Mechanistic Studies of the Pd- and Pt-Catalyzed Selective Cyclization of Propargyl/Allenyl Complexes

Following the discovery of an unusual transition-metal-catalyzed reaction, the elucidation of the underlying mechanism is essential to understand the characteristic reactivity of the metal. We previously reported a synthetic method for tricyclic indoles using Pt-catalyzed Friedel-Crafts-type C-H coupling. In this reaction, the Pt catalyst selectively formed a seven-membered ring, but the Pd catalyst only afforded a six-membered ring. However, the reasons for the different selectivities caused by Pd and Pt were unclear. We performed density functional theory (DFT) calculations and experimental studies to reveal the origin of the different behaviors of the two metals. The calculations revealed that the formation of the six- and seven-membered rings proceeds via η1-allenyl and η3-propargyl/allenyl complexes, respectively. A molecular orbital analysis of the η3-propargyl/allenyl complex revealed that, for the platinum complex, the energy required to convert the unoccupied molecular orbital on the reactive carbon into the lowest unoccupied molecular orbital (LUMO) was lower than that for the palladium complex. In addition, DFT calculations revealed that the combination of platinum and bis[2-(diphenylphosphino)phenyl] ether (DPEphos) reduced the activation energy of the seven-membered cyclization in comparison with palladium or PPh3. Additional experimental studies, including NMR studies and stoichiometric reactions, support the aforementioned examination.

Dephosphorization in Double Slag Converter Steelmaking Process at Different Temperatures by Industrial Experiments

In the present work, the effect of dephosphorization endpoint temperature on the dephosphorization of hot metal was studied for the double slag converter steelmaking process under the conditions of low temperature and low basicity by the industrial experiments. In the temperature range of 1350–1450 °C, with an increasing dephosphorization endpoint temperature, the dephosphorization ratio and phosphorus distribution ratio first increase and then decrease. The phosphorus content in hot metal first decreases and then increases at the end of dephosphorization. At the dephosphorization temperature range of 1385–1410 °C, the dephosphorization ratio is higher than 55%, the P2O5 content in the dephosphorization slag is 3.93–4.17%, the logLP value is 1.76–2.09, the value of PCOP-C of the selective oxidation reaction of carbon and phosphorus is 53–80 Pa, and the aFeO value is 0.284–0.312. The path of phosphorus in hot metal entering the P-rich phase of dephosphorization slag can be reasonably inferred as: hot metal → Fe-rich phase → P-rich phase. Under the present industrial experimental conditions, the dephosphorization and rephosphorization reactions are in dynamic equilibrium at 1413 °C. Considering the experimental results and thermodynamic calculation results of industrial experiments by the double slag dephosphorization process, the optimal temperature range for intermediate deslagging is about 1400–1420 °C.

Harpagide Inhibits Microglial Activation and Protects Dopaminergic Neurons as Revealed by Nanoelectrode Amperometry†

Main observation and conclusionParkinson's disease (PD) is one of the most common neurogenerative diseases (NDDs), characterized as less neurotransmitter release and loss of dopaminergic (DAergic) neurons with microglial inflammatory response as a key player. Natural product harpagide with anti‐inflammatory function is a potential therapeutic drug of PD, but its role towards microglial activation and inflammation‐mediated neuronal injury remained unsure. In this work, taking advantage of nanoelectrode amperometry with high temporal‐spatial resolution, we used nanowire electrodes (NWEs) to monitor intracellular reactive oxygen species (ROS) level and carbon fiber nanoelectrodes (CFNEs) to detect synaptic dopamine exocytosis, to explore the effect of harpagide in modulating microglial inflammatory reaction and protecting DAergic neurons in neuron‐microglia co‐culture system. The results indicate that harpagide inhibits microglia from activation induced by LPS/IFN‐γ and generation of ROS, therefore reduces inflammation‐mediated neural injury and maintains dopamine exocytosis function. These conclusions establish that harpagide possesses promising avenues for preventive or therapeutic interventions against PD and other NDDs.

Mechanical and Microstructural Characteristics of Calcium Sulfoaluminate Cement Exposed to Early-Age Carbonation Curing.

The early-age carbonation curing technique is an effective way to improve the performance of cement-based materials and reduce their carbon footprint. This work investigates the early mechanical properties and microstructure of calcium sulfoaluminate (CSA) cement specimens under early-age carbonation curing, considering five factors: briquetting pressure, water–binder (w/b) ratio, starting point of carbonation curing, carbonation curing time, and carbonation curing pressure. The carbonization process and performance enhancement mechanism of CSA cement are analyzed by mercury intrusion porosimetry (MIP), thermogravimetry and derivative thermogravimetry (TG-DTG) analysis, X-ray diffraction (XRD), and scanning electron microscope (SEM). The results show that early-age carbonation curing can accelerate the hardening speed of CSA cement paste, reduce the cumulative porosity of the cement paste, refine the pore diameter distribution, and make the pore diameter distribution more uniform, thus greatly improving the early compressive strength of the paste. The most favorable w/b ratio for the carbonization reaction of CSA cement paste is between 0.15 and 0.2; the most suitable carbonation curing starting time point is 4 h after initial hydration; the carbonation curing pressure should be between 3 and 4 bar; and the most appropriate time for carbonation curing is between 6 and 12 h.

Offshore Windfarm Footprint of Sediment Organic Matter Mineralization Processes

Offshore windfarms (OWFs) offer part of the solution for the energy transition which is urgently needed to mitigate effects of climate change. Marine life has rapidly exploited the new habitat offered by windfarm structures, resulting in increased opportunities for filter- and suspension feeding organisms. In this study, we investigated the effects of organic matter (OM) deposition in the form of fecal pellets expelled by filtering epifauna in OWFs, on mineralization processes in the sediment. OM deposition fluxes produced in a 3D hydrodynamic model of the Southern Bight of the North Sea were used as input in a model of early diagenesis. Two scenarios of OWF development in the Belgian Part of the North Sea (BPNS) and its surrounding waters were calculated and compared to a no-OWF baseline simulation. The first including constructed OWFs as of 2021, the second containing additional planned OWFs by 2026. Our results show increased total mineralization rates within OWFs (27–30%) in correspondence with increased deposition of reactive organic carbon (OC) encapsulated in the OM. This leads to a buildup of OC in the upper sediment layers (increase by ∼10%) and an increase of anoxic mineralization processes. Similarly, denitrification rates within the OWFs increased, depending on the scenario, by 2–3%. Effects were not limited to the OWF itself: clear changes were noticed in sediments outside of the OWFs, which were mostly opposite to the “within-OWF” effects. This contrast generated relatively small changes when averaging values over the full modeling domain, however, certain changes, such as for example the increased storage of OC in sediments, may be of significant value for national / regional carbon management inventories. Our results add to expectations of ecosystem-wide effects of windfarms in the marine environments, which need to be researched further given the rapid rate of expansion of OWFs.

Towards a chemical mechanism of the oxidation of aqueous sulfur dioxide via isoprene hydroxyl hydroperoxides (ISOPOOH)

Abstract. In-cloud chemistry has important ramifications for atmospheric particulate matter formation and gas-phase chemistry. Recent work has shown that, like hydrogen peroxide (H2O2), the two main isomers of isoprene hydroxyl hydroperoxide (ISOPOOH) oxidize sulfur dioxide dissolved in cloud droplets (SO2,aq) to sulfate. The work revealed that the pathway of SO2,aq oxidation with ISOPOOH differs from that of H2O2. We investigate the chemical mechanisms of oxidation of SO2,aq with ISOPOOH in the cloud-relevant pH range of 3–6 and compare them with the previously reported mechanisms of oxidation of SO2,aq with H2O2, methyl hydroperoxide and peroxyacetic acid. The organic products of the reaction are identified, and two pathways are proposed. For 1,2-ISOPOOH, a higher yield pathway via proposed radical intermediates yields methyl vinyl ketone (MVK) and formaldehyde, which can react to hydroxymethanesulfonate (HMS) when SO2,aq is present. A lower yield non-fragmentation oxygen addition pathway is proposed that results in the formation of isoprene-derived diols (ISOPOH). Based on global simulations, this mechanism is not a significant pathway for formation of MVK and formaldehyde relative to their gas-phase formation but, as previously reported, it can be regionally important for sulfate production. The study adds to previous work that highlights similarities and differences between gas-phase and cloud-droplet processing of reactive organic carbon.

Research on carbonization kinetic of cellulose-based materials and its application

As a renewable resource, cellulose-based material (CBM) is frequently adopted to prepare functional carbon materials, which have been extensively used in the fields of catalysis, environment protection and energy. It is important for researchers in material field to quickly obtain methods for the carbonization kinetic analysis of CBM. In this work, a framework method for quickly determining carbonization process and kinetics parameters is developed. The new framework method employed inventive initial estimation, binary tree assumption, linear programming together with rigorous experimental verification. According to TG experiment data, CBM is divided into two parts marked by free-ends of raw material (corresponding 10 % with free-end in MCC), which undergo different reaction. The results of optimized model show the isothermal TG data has a high accordance, the max Root Mean Squared Error (RMSE) of 0.01, as well as the max RMSE under constant heating rate is 0.009. Furthermore, as a demonstration of using new framework, carbonization reaction of nanocellulose (NNC) is primitively investigated.

Innovative one-step preparation of activated carbon from low-rank coals activated with oxidized pellets

The research proposed an innovative, efficient, and clean process which used low-rank coals and oxidized pellets as carbon-based feedstocks and activators for one-step preparation of activated carbon with direct reduction iron as co-production. The co-effect between low-rank coals and oxidized pellets was disclosed. The properties characterization of activated carbon was comprehensively analyzed as well. The results indicated that semi-coke can be produced via the pyrolysis and carbonization of low-rank coal, which is the raw material of activated carbon and the reductant of oxidized pellets. Meanwhile, CO2, generated circularly via the reduction of iron oxides, acts as the activating agent of semi-coke to produce activated carbon. Furthermore, CO, generated via gasification reaction of carbon, can act as the main reductant for the reduction of iron oxides. Under the optimum conditions of SF coal as carbon-based feedstock, activated temperature of 850 °C for 140 min with C/Fe of 2.0, one-step prepared activated carbon, characterised by specific surface area of 370.42 m2 g−1, iodine sorption value of 685.67 mg g−1, compressive strength of 234.67 N·per−1, can be obtained with direct reduction iron as co-production processing metallization ratio of 86.96%. Compared with commercial activated carbon, the new SF activated carbon possesses a more superior microstructure, higher graphitization degree, preferable composition, and content of functional groups for its better adsorption property and compressive strength.

Bacteria fixing CO2 to enhance the volume stability of ground steel slag powder as a component of cement-based materials aiming at clean production

Steel slag is a by-product in the process of steel manufacture. It has caused huge environmental pressure. The use of steel slag as the admixture of cement-based materials is an effective way to enhance clean production. But the poor volume stability caused by dead burned lime and periclase in steel slag is a crucial factor restricting its utilization. Some research has shown that carbonization could convert dead burned lime and periclase into carbonate. But the carbonization rate and carbonization degree were low. The objective of this paper is to adopt Bacillus Mucilaginosus (BM) to absorb carbon dioxide to promote the carbonization of dead burned lime and periclase, thereby enhancing steel slag utilization in cement-based materials. The effects of BM on the carbonization rate and degree of dead burned lime and periclase were studied by conducting experiments; the influence of BM on the stability of steel slag mortar with different particle sizes was studied. The results show that BM can reduce the apparent activation energy of the carbonization reaction of dead burnt lime and periclase, and increase the reaction rate and maximum reactivity. MIP (Mercury Intrusion Porosimetry) analysis found that steel slag mortar specimen with BM had a lower porosity than that without BM. The autoclaved linear expansion rate of the steel slag mortar specimen with BM can meet standard requirements while that without BM cannot. It is indicated that the addition of BM can effectively promote the carbonization of dead burned lime and periclase in steel slag and solve the problem of poor volume stability of cement-based materials caused by steel slag. This research helps to improve the utilization of steel slag as an alternative binder to cement and alleviates the environmental pressure caused by the storage of waste steel slag.

Performance Analysis of TiO2-Modified Co/MgAl2O4 Catalyst for Dry Reforming of Methane in a Fixed Bed Reactor for Syngas (H2, CO) Production

Co/TiO2–MgAl2O4 was investigated in a fixed bed reactor for the dry reforming of methane (DRM) process. Co/TiO2–MgAl2O4 was prepared by modified co-precipitation, followed by the hydrothermal method. The active metal Co was loaded via the wetness impregnation method. The prepared catalyst was characterized by XRD, SEM, TGA, and FTIR. The performance of Co/TiO2–MgAl2O4 for the DRM process was investigated in a reactor with a temperature of 750 °C, a feed ratio (CO2/CH4) of 1, a catalyst loading of 0.5 g, and a feed flow rate of 20 mL min−1. The effect of support interaction with metal and the composite were studied for catalytic activity, the composite showing significantly improved results. Moreover, among the tested Co loadings, 5 wt% Co over the TiO2–MgAl2O4 composite shows the best catalytic performance. The 5%Co/TiO2–MgAl2O4 improved the CH4 and CO2 conversion by up to 70% and 80%, respectively, while the selectivity of H2 and CO improved to 43% and 46.5%, respectively. The achieved H2/CO ratio of 0.9 was due to the excess amount of CO produced because of the higher conversion rate of CO2 and the surface carbon reaction with oxygen species. Furthermore, in a time on stream (TOS) test, the catalyst exhibited 75 h of stability with significant catalytic activity. Catalyst potential lies in catalyst stability and performance results, thus encouraging the further investigation and use of the catalyst for the long-run DRM process.

Temperature enhances the ohmic and mass transport behaviour in membrane electrode assembly carbon dioxide electrolyzers

The operating temperature is a critical parameter for improving the performance of a carbon dioxide electrolyzer. Specifically, the power density reduced by up to 35% (at 215 mA/cm2) when increasing the operating temperature from 25 °C to 60 °C, and increasing the cell temperature led to significantly lower ohmic resistances and mass transport limitations. A 5–fold reduction in ohmic resistance (from 3.35 Ω·cm2 to 0.64 Ω·cm2) was achieved by increasing the cell temperature from 25 °C to 60 °C at 215 mA/cm2. These reductions in ohmic overvoltages were attributed to higher cation exchange membrane water content at higher operating temperatures observed via synchrotron X-ray radiography. The higher water content at higher temperatures was attributed to the relaxation of the polymer backbone of the membrane. The dominating mechanisms for mass transport limitations at high current densities (≥305 mA/cm2) were temperature dependent. Specifically, at 40 °C, liquid water in the electrode inhibited reactant carbon dioxide transport to the reaction sites; whereas, at 60 °C, the product gas saturation in the electrode inhibited mass transport. However, a higher temperature led to consistently lower mass transport losses at each current density (e.g., a reduction from 0.75 V to 0.37 V at 395 mA/cm2 when increasing the temperature from 40 °C to 60 °C) since less water accumulated in the cathode gas diffusion layer.

An efficient approach to diarylethene-amino acid photochromic fluorescent hybrids

• An effective approach to creating photo-controlled diarylethene-amino acid hybrids. • X-ray diffraction study, spectral luminescent and photochromic properties. • Thermally and photochemically reversible intramolecular photocyclization. • Dependence of the photoinduced form stability on the structure. • Modulation of emission under successive irradiation with light of different wavelengths. An effective approach to the synthesis of diarylethene-amino acid hybrids DE-Gly, DE-AABA and DE-DAA ( 5a-d - 7-a-d ) was developed via condensation of furan-2,5-dione-based diarylethenes (DE) and ethyl esters of glycine (Gly), α-aminobutyric acid (AABA) and D-aspartic acid (DAA) with moderate to good yields. According to X-ray diffraction data, DE-Gly hybrid 5a exists in an antiparallel conformation with a distance of 4.549 Å between the reactive carbon atoms C(1)-C(11), potentially capable of forming a single bond, which is suitable for the conrotatory photocyclization reaction allowed by the Woodward-Hoffman rules. The structures of the obtained compounds were proved by 1 H, COZY, HSQC, HMBC and 13 C NMR spectroscopy. The hybrids DE-Gly, DE-AABA and DE-DAA absorb at 443–456 nm, which corresponds to their existence in a ring-open form O, and display fluorescence at 531–612 nm. Irradiation with light of 436 nm results in their rearrangement into ring-closed colored nonfluorescent isomers C. Backwards re-opening occurs under the action of visible light (λ > 500 nm). Spectral kinetic investigation of 5a,c revealed that the efficiency of photocyclization, as well as the emission quantum yield, decreases with the growth of solvent polarity. The ring-closed isomer C of sterically hindered 5a (R 2 = R 3 = Me) is stable at room temperature, whereas for 5c (R 3 = H), ring opening readily occurs with the speed increasing with the polarity of the solvent. The internal emission of sterically hindered hybrids 5a, 6a and 7a (R 2 = R 3 = Me) is reversibly modulated in a binary response with good fatigue resistance under successive irradiation with light of 436 and 540 nm.

Molten Salt Templated Synthesis of Covalent Isocyanurate Frameworks with Tunable Morphology and High CO2 Uptake Capacity.

The use of reactive molten salts, i.e., ZnCl2, as a soft template and a catalyst has been actively investigated in the preparation of covalent triazine frameworks (CTFs). Although the soft templating effect of the salt melt is more prominent at low temperatures, close to the melting point of ZnCl2, leading to the formation of abundant micropores, a significant mesopore formation is observed that is due to the partial carbonization and other side reactions at higher temperatures (>400 °C). Evidently, high-temperature synthesis of CTFs in various eutectic salt mixtures of ZnCl2 with alkali metal chloride salts also leads to mesopore formation. We reasoned that using the isocyanate moieties instead of cyano groups in the monomer, 1,4-phenylene isocyanate, could enable efficient interactions between carbonyl moieties and alkali metal ions to realize efficient salt templating to form covalent isocyanurate frameworks (CICFs). In this direction, the trimerization of 1,4-phenylene diisocyanate was carried out under ionothermal conditions at different reaction temperatures using ZnCl2 (CICF) and the eutectic salt mixture of KCl/NaCl/ZnCl2 (CICF-KCl/NaCl) as the reactive solvents. We observed notable differences in the morphologies of the two polymers, whereas CICF showed irregular-shaped micrometer-sized particles, the CICF-KCl/NaCl exhibited a filmlike morphology. Moreover, favorable ion-dipole interactions between alkali metal cations and oxygen atoms of the monomer facilitated two-dimensional growth and the formation of a purely microporous framework in the case of CICF-KCl/NaCl along with a near theoretical retention of the nitrogen content at 500 °C. The CICF-KCl/NaCl showed a BET surface area of 590 m2 g-1 along with a CO2 uptake capacity of 5.9 mmol g-1 at 273 K and 1.1 bar because of its high microporosity and nitrogen content. On the contrary, in the absence of alkali metal ions, CICF showed high mesopore content and a moderate CO2 uptake capacity. This study underscores the importance of the strength of the interactions between the salts and the monomer in the ionothermal synthesis to control the morphology, porosity, and gas uptake properties of the porous organic polymers.

Recent progress in developing fluorescent probes for imaging cell metabolites

Cellular metabolites play a crucial role in promoting and regulating cellular activities, but it has been difficult to monitor these cellular metabolites in living cells and in real time. Over the past decades, iterative development and improvements of fluorescent probes have been made, resulting in the effective monitoring of metabolites. In this review, we highlight recent progress in the use of fluorescent probes for tracking some key metabolites, such as adenosine triphosphate, cyclic adenosine monophosphate, cyclic guanosine 5'-monophosphate, Nicotinamide adenine dinucleotide (NADH), reactive oxygen species, sugar, carbon monoxide, and nitric oxide for both whole cell and subcellular imaging.

A novel machine learning-based approach for prediction of nitrogen content in hydrochar from hydrothermal carbonization of sewage sludge

In this work, 138 datapoints, including elemental composition and ultimate analysis of various types of sewage sludge, and the hydrothermal carbonization reaction conditions, are used to develop a prediction model for the nitrogen content of the hydrochar. The results suggested that a two-layer feedforward neural network with five (05) neurons in the hidden layer can accurately predict the nitrogen content of the hydrochar based on the reaction temperature and the contents of nitrogen, carbon, volatiles and fixed carbon in the feedstock. Over 100 runs, the R2 and RMSE are in [87.547–99.097%] and [0.243–1.431] wt.% (db), respectively. Moreover, a statistical and regression analysis revealed that the sewage sludge-N is the main contributor to the hydrochar-N. Mostly, 40–70% of sewage sludge-N goes to hydrochar-N. The results are consistent with previous experimental reports, and this model can be used to predict the sewage sludge-derived hydrochar-N.

Comprehensive evaluation of the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis against independent observations

The Copernicus Atmosphere Monitoring Service (CAMS) is operationally providing forecast and reanalysis products of air quality and atmospheric composition. In this article, we present an extended evaluation of the CAMS global reanalysis data set of four reactive gases, namely, ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), and formaldehyde (HCHO), using multiple independent observations. Our results show that the CAMS model system mostly provides a stable and accurate representation of the global distribution of reactive gases over time. Our findings highlight the crucial impact of satellite data assimilation and emissions, investigated through comparison with a model run without assimilated data. Stratospheric and tropospheric O3 are mostly well constrained by the data assimilation, except over Antarctica after 2012/2013 due to changes in the assimilated data. Challenges remain for O3 in the Tropics and high-latitude regions during winter and spring. At the surface and for short-lived species (NO2), data assimilation is less effective. Total column CO in the CAMS reanalysis is well constrained by the assimilated satellite data. The control run, however, shows large overestimations of total column CO in the Southern Hemisphere and larger year-to-year variability in all regions. Concerning the long-term stability of the CAMS model, we note drifts in the time series of biases for surface O3 and CO in the Northern midlatitudes and Tropics and for NO2 over East Asia, which point to biased emissions. Compared to the previous Monitoring Atmospheric Composition and Climate reanalysis, changes in the CAMS chemistry module and assimilation system helped to reduce biases and enhance the long-term temporal consistency of model results for the CAMS reanalysis.