Abundant Ions Research Articles

Air-Stable Na3.5C6O6 as a Sodium Compensation Additive in Cathode of Na-Ion Batteries.

Sodium-ion battery (SIB) is a candidate for the stationary energy storage systems because of the low cost and high abundance of sodium. However, the energy density and lifespan of SIBs suffer severely from the irreversible consumption of the Na-ions for the formation of the solid electrolyte interphase (SEI) layer and other side reactions on the electrodes. Here, Na3.5C6O6 is proposed as an air-stable high-efficiency sacrificial additive in the cathode to compensate for the lost sodium. It is characteristic of low desodiation (oxidation) potential (3.4-3.6V vs. Na+/Na) and high irreversible desodiation capacity (theoretically 378 mAh g-1). The feasibility of using Na3.5C6O6 as a sodium compensation additive is verified with the improved electrochemical performances of a Na2/3Ni1/3Mn1/3Ti1/3O2ǀǀhard carbon cells and cells using other cathode materials. In addition, the structure of Na3.5C6O6 and its desodiation path are also clarified on the basis of comprehensive physical characterizations and the density functional theory (DFT) calculations. This additive decomposes completely to supply abundant Na ions during the initial charge without leaving any electrochemically inert species in the cathode. Its decomposition product C6O6 enters the carbonate electrolyte without bringing any detectable negative effects. These findings open a new avenue for elevating the energy density and/or prolonging the lifetime of the high-energy-density secondary batteries.

Investigation of Combustion and NO/SO2 Emission Characteristics during the Co-Combustion Process of Torrefied Biomass and Lignite.

This paper investigates the combustion characteristics and pollutant emission patterns of the mixed combustion of lignite (L) and torrefied pine wood (TPW) under different blending ratios. Isothermal combustion experiments were conducted in a fixed bed reaction system at 800 °C, and pollutant emission concentrations were measured using a flue gas analyzer. Using scanning electron microscopy (SEM) and BET (nitrogen adsorption) experiments, it was found that torrefied pine wood (TPW) has a larger specific surface area and a more developed pore structure, which can facilitate more complete combustion of the sample. The results of the non-isothermal thermogravimetric analysis show that with the TPW blending ratio increase, the entire combustion process advances, and the ignition temperature, maximum peak temperature, and burnout temperature all show a decreasing trend. The kinetic equations of the combustion reaction process of mixed gas were calculated by Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) kinetic equations. The results show that the blending of TPW reduces the activation energy of the combustion reaction of the mixed fuel. When the TPW blending ratio is 80%, the activation energy values of the mixed fuel are the lowest at 111.32 kJ/mol and 104.87 kJ/mol. The abundant alkali metal ions and porous structure in TPW reduce the conversion rates of N and S elements in the fuel to NO and SO2, thus reducing the pollutant emissions from the mixed fuel.

Electrospray ionization tandem mass spectrometry of 4-aryl-3,4-dihydrocoumarins.

We have investigated the gas-phase fragmentation reactions of 11 synthetic 4-aryl-3,4-dihydrocoumarins by electrospray ionization tandem mass spectrometry (ESI-MS/MS) on a quadrupole-time-of flight (Q-TOF) hybrid mass spectrometer. We have also estimated thermochemical data for the protonated coumarins (precursor ion A) and product ion structures by computational chemistry at a B3LYP level of theory to establish the ion structures and to rationalize the fragmentation pathways. The most abundant ions in the product ion spectra of coumarins 1-11 resulted from C8H8O2, CO2, C4H4O3, C8H10O3, C8H8O2, and CH3OH eliminations through retro-Diels-Alder (RDA) reactions, remote hydrogen rearrangements (β-eliminations), and β-lactone ring contraction. Although the investigated coumarins shared most of the fragmentation pathways, formation of a benzylic product ion and its corresponding tropylium ion was diagnostic of the substituents at ring C. The thermochemical data revealed that the nature and position of the substituents at ring C played a key role in the formation of this product ion and determined its relative intensity in the product ion spectrum. The results of this study contribute to knowledge of the gas-phase ion chemistry of this important class of organic compounds.

High Ion-Conducting PVA Nanocomposite Hydrogel-Based Wearable Piezoelectric and Triboelectric Sensors for Harsh Environments.

Traditional hydrogel-based wearable sensors with flexibility, biocompatibility, and mechanical compliance exhibit potential applications in flexible wearable electronics. However, the low sensitivity and poor environmental resistance of traditional hydrogels severely limit their practical application. Herein, high-ion-conducting poly(vinyl alcohol) (PVA) nanocomposite hydrogels were fabricated and applied for harsh environments. MXene ion-conducting microchannels and poly(sodium 4-styrenesulfonate) ion sources contributed to the directional transport of abundant free ions in the hydrogel, which significantly improved the sensitivity and mechanical-electric conversion of the nanocomposite hydrogel-based piezoelectric and triboelectric sensors. More importantly, the glycerol as an antifreezing agent enabled the hydrogel-based sensors to function in harsh environments. Therefore, the nanocomposite hydrogel exhibited high gauge factor (GF) at -20 °C (GF = 3.37) and 60 °C (GF = 3.62), enabling the hydrogel-based sensor to distinguish different writing letters and sounding words. Meanwhile, the hydrogel-based piezoelectric and triboelectric generators showed excellent mechanical-electric conversion performance regardless of low- (-20 °C) or high- (60 °C) temperature environments, which can be applied as a visual feedback system for information transmission without external power sources. This work provides self-powered nanocomposite hydrogel-based sensors that exhibit potential applications in flexible wearable electronics under harsh environmental conditions.

CLASSY. IX. The Chemical Evolution of the Ne, S, Cl, and Ar Elements

To study the chemical evolution across cosmic epochs, we investigate Ne, S, Cl, and Ar abundance patterns in the Cosmic Origins Spectrograph Legacy Archive Spectroscopic SurveY (CLASSY). CLASSY comprises local star-forming galaxies (SFGs; 0.02 < z < 0.18) with enhanced star formation rates, making them strong analogues to high-z SFGs. With direct measurements of electron temperature, we derive accurate ionic abundances for all elements and assess ionization correction factors (ICFs) to account for unseen ions and derive total abundances. We find Ne/O, S/O, Cl/O, and Ar/O exhibit constant trends with gas-phase metallicity for 12+log(O/H) < 8.5 but significant correlation for Ne/O and Ar/O with metallicity for 12+log(O/H) > 8.5, likely due to ICFs. Thus, the applicability of the ICFs to integrated spectra of galaxies could bias results, underestimating true abundance ratios. Using CLASSY as a local reference, we assess the evolution of Ne/O, S/O, and Ar/O in galaxies at z > 3, finding no cosmic evolution of Ne/O, while the lack of direct abundance determinations for S/O and Ar/O can bias the interpretation of the evolution of these elements. We determine the fundamental metallicity relationship (FMR) for CLASSY and compare to the high-redshift FMR, finding no evolution. Finally, we perform the first mass–neon relationship analysis across cosmic epochs, finding a slight evolution to high Ne at later epochs. The robust abundance patterns of CLASSY galaxies and their broad range of physical properties provide essential benchmarks for interpreting the chemical enrichment of the early galaxies observed with the JWST.

Optimizing neurotransmitter pathway detection by IR-MALDESI-MSI in mouse brain.

Mass spectrometry imaging (MSI) platforms such as infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) are advantageous for a variety of applications, including elucidating the localization of neurotransmitters (NTs) and related molecules with respect to ion abundance across a sample without the need for derivatization or organic matrix application. While IR-MALDESI-MSI conventionally uses a thin exogenous ice matrix to improve signal abundance, it has been previously determined that sucrose embedding without the ice matrix improves detection of lipid species in striatal, coronal mouse brain sections. This work considers components of this workflow to determine the optimal sample preparation and matrix to enhance the detection of NTs and their related metabolites in coronal sections from the striatal region of the mouse brain. The discoveries herein will enable more comprehensive follow-on studies for the investigation of NTs to enrich biological pathways and interpretation related to neurodegenerative diseases and ischemic stroke.

Quaternized chitosan/polyvinyl alcohol anion exchange membrane enhanced by functionalized attapulgite clay with an ionic “chain-ball” surface structure

Biomass chitosan has garnered considerable interest for alkaline anion exchange membranes (AEMs) due to its eco-friendly and sustainable characteristics, low reactant permeability and easily modifiable nature, but it still faces the trade-off between high hydroxide conductivity and sufficient mechanical properties. Herein, a novel functionalized attapulgite clay (f-ATP) with a unique ionic “chain-ball” surface structure was prepared and incorporated with quaternized chitosan (QCS)/polyvinyl alcohol (PVA) matrix to fabricate high-performance composite AEMs. Due to the strengthened interfacial bonding between f-ATP nanofillers and the QCS/PVA matrix, composite membranes are synergistically reinforced and toughened, achieving peak tensile strength and elongation at break of 24.62 MPa and 33.8 %. Meanwhile, abundant ion pairs on f-ATP surface facilitate ion transport in the composite AEMs, with the maximum OH− conductivity of 46 mS cm−1 at 80 °C and the highest residual IEC of 83 % after alkaline treatment for 120 h. Moreover, the assembled alkaline direct methanol fuel cell exhibits a remarkable power density of 49.3 mW cm−2 at 80 °C. This work provides a new strategy for fabricating high-performance anion exchange membranes.

Differentiation of Δ9-THC and CBD Using Silver-Ligand Ion Complexation and Electrospray Ionization Tandem Mass Spectrometry (ESI-MS/MS).

The 2018 Farm Bill defines marijuana as Cannabis sativa L. or any derivative thereof that contains greater than 0.3% Δ9-tetrahydrocannabinol (Δ9-THC) on a dry weight basis. The main cannabinoids present in Cannabis sativa L., Δ9-THC and cannabidiol (CBD), are structural isomers that cannot be differentiated using direct mass spectrometry with soft ionization techniques alone. Due to the classification of marijuana as a Schedule I controlled substance, the differentiation of Δ9-THC and CBD is crucial within the seized drug community. This study explores the use of Ag-ligand ion complexation and electrospray ionization tandem mass spectrometry (ESI-MS/MS) for the differentiation of Δ9-THC and CBD using six different Ag complexes. Differences between the binding affinities of Δ9-THC and CBD for [Ag(PPh3)(OTf)]2 lead to the formation of unique product ions at m/z 421/423, m/z 353/355, and m/z 231 for CBD, enabling the differentiation of CBD from Δ9-THC. When applied to the analysis of known Δ9-THC:CBD mixture ratios, the developed [Ag(PPh3)(OTf)]2 ion complexation method was able to differentiate Δ9-THC-rich and CBD-rich samples based on the average abundance of the product ions at m/z 421/423. The developed approach was then applied to methanolic extracts of 20 authentic cannabis samples with known Δ9-THC and CBD compositions, resulting in a 95% correct classification rate. Even though the developed Ag-ligand ion complexation method was only demonstrated for the qualitative differentiation of Δ9-THC-rich and CBD-rich cannabis, this study establishes a foundation for the use of Ag-ligand ion complexation that is essential for future quantitative approaches.

Comparison of Ion–Proton Differential Speed between Interplanetary Coronal Mass Ejections and Solar Wind near 1 au

The elemental abundance of interplanetary coronal mass ejections (ICMEs) and solar wind near 1 au is often adopted to represent the abundance in the corresponding coronal sources. However, the absolute abundance of heavy ions (relative to hydrogen) near 1 au might be different from the coronal abundance due to the ion–proton differential speed (V ip ). To illustrate the V ip characteristics and explore whether it influences the absolute abundance analysis for ICMEs and solar wind, we perform a statistical study on the V ip for He2+, C5+, O6+, and Fe10+ in both ICMEs and solar wind based on measurements of Advanced Composition Explorer. The results show that the V ip is negligible within ICMEs and slow solar wind (< 400 km s−1), while obvious in the intermediate (400–600 km s−1) and fast wind (> 600 km s−1). Previous studies showed that the V ip in ICMEs keeps negligible during propagation from 0.3 to 5 au, but in solar wind it increases with the decreasing heliocentric distance. Therefore, it might be questionable to infer the absolute abundance of coronal sources through in situ abundance near 1 au for solar wind. Fortunately, the ion–oxygen (O6+) differential speed (V io ) is negligible for He2+, C5+, and Fe10+ within both ICMEs and solar wind, and previous studies suggested that the V io does not vary significantly with the heliocentric distance. This indicates that various heavy ions always flow at the same bulk speed and their relative abundance (relative to oxygen) near 1 au can represent the coronal abundance for both ICMEs and solar wind.

Mutual-benefit modification of the coagulant solution and fly ash for enhanced sludge dewatering

Faced with the escalating volume of municipal sludge from wastewater treatment plants, urgent measures are required to enhance the sludge dewatering efficiency. This study introduces an innovative and cost-effective approach for mutual modifications of AlCl3 coagulant solution (AC) and fly ash (FA) powder as additives to significantly enhance sludge dewaterability. Unlike the traditional method that modifies agents alone, our technique achieves dual functionalities via blending FA with AC at room temperature. The modified FA (MFA) exhibits a 60 % increase in specific surface area to 2.176 m2/g and ζ-potential shift from –22.2 to +2.0 mV, meanwhile enhances the metal ions content in the modified AC (MAC) by dissolving 96.5 % of Ca, 70.3 % of Mg, 10.6 % of Fe, and 6.1 % of Al ions from FA. When sludge is treated with 5 % MAC and 10 % MFA, the water content in the filter cake is reduced from 84.9 % originally to 52.9 % through plate-frame pressure filtration (PFPF), a significant improvement over 65.4 % for that with unmodified AC and FA treatment, corresponding to the decreased specific resistance to filtration (SRF) and increased the filtration flux during the draining phase. The notable dewaterability enhancement through AC and FA modification is due to the enhanced flocculation and charge neutralization by the abundant metal ions in MAC, coupled with the MFA-facilitated water adsorption and drainage channel maintenance. This one-step, double-benefit modification not only surpasses traditional methods in dewatering efficiency but also reduces sludge treatment costs by 42.4 %, offering a sustainable solution to the increasing challenges of municipal sludge management.

Optimization of on-site wastewater treatment efficiency and recovery based on nutrient mobility and adsorption kinetics modelling using HYDRUS-2D coupled with PHREEQC

A closed-loop on-site wastewater treatment system (OWT) was studied comprising steps of septic tank to remove organics (Biological Oxygen Demand (BOD)), biofiltration clarifier for biological removal of nitrogen (N), phosphorus (P) and BOD, reactive Polonite® filter for chemical adsorption and precipitation removal of dissolved P, and tidal flow constructed wetland (TFCW) sand filter for polishing the effluent to low P and N effluent Swedish standards. The field experimental data that have been used to optimize TFCW design in the numerical modelling using HYDRUS-2D coupled with and without PHREEQC indicated that the adsorption efficiency of the reactive Polonite® adsorbent was nearly double to that obtained in TFCW sand filters for PO4-P (95 %) and Total-P (85 %) removal in summer at a high temperature range (15.4–18.8 °C) and pH range (9.9–10.8). The weaker PO4-P (53 %) and Total-P (25 %) removal efficiency in winter was due to a low temperature (1.5–8.1 °C) and low pH (7.2–7.9). This decrease in pH was attributed to salinity in the domestic wastewater and dilution of rainwater. Modelling results revealed that the transport mechanisms and rate of P adsorption kinetics in the TFCW sand filters enhanced with calcium and iron flow from chemical dissolution in the preceding Polonite® adsorbent was increased with the increase in temperature. However, the P adsorption was less sensitive at high ferrihydrite (Fe(OH)3) dose, suggesting limited effects of cations dissolution and abundance of metal oxides and hydroxide ions at the mineral surface for anions exchange with phosphate for surface complexation. The strategy of combining field data and modelling provided valuable insights for assessing adaptability and optimizing TFCW design under variable fluxes and scenario effects of insulated/uninsulated and dilution by rainwater in cold-climate regions.

Self-Limiting Phase Transition Enabling Reversible Overstoichiometric Li Storage in Ni-Rich Cathodes.

Ni-rich cathodes are some of the most promising candidates for advanced lithium-ion batteries, but their available capacities have been stagnant due to the intrinsic Li+ storage sites. Extending the voltage window down can induce the phase transition from O3 to 1T of LiNiO2-derived cathodes to accommodate excess Li+ and dramatically increase the capacity. By setting the discharge cutoff voltage of LiNi0.6Co0.2Mn0.2O2 to 1.4 V, we can reach an extremely high capacity of 393 mAh g-1 and an energy density of 1070 Wh kg-1 here. However, the phase transition causes fast capacity decay and related structural evolution is rarely understood, hindering the utilization of this feature. We find that the overlithiated phase transition is self-limiting, which will transform into solid-solution reaction with cycling and make the cathode degradation slow down. This is attributed to the migration of abundant transition metal ions into lithium layers induced by the overlithiation, allowing the intercalation of overstoichiometric Li+ into the crystal without the O3 framework change. Based on this, the wide-potential cycling stability is further improved via a facile charge-discharge protocol. This work provides deep insight into the overstoichiometric Li+ storage behaviors in conventional layered cathodes and opens a new avenue toward high-energy batteries.

Biomass Solid-State Electrolyte with Abundant Ion and Water Channels for Flexible Zinc-Air Batteries.

Flexible zinc-air batteries are the leading candidates as the next-generation power source for flexible/wearable electronics. However, constructing safe and high-performance solid-state electrolytes (SSEs) with intrinsic hydroxide ion (OH-) conduction remains a fundamental challenge. Herein, by adopting the natural and robust cellulose nanofibers (CNFs) as building blocks, the biomass SSEs with penetrating ion and water channels are constructed by knitting the OH--conductive CNFs and water-retentive CNFs together via an energy-efficient tape casting. Benefiting from the abundant ion and water channels with interconnected hydrated OH- wires for fast OH- conduction under a nanoconfined environment, the biomass SSEs reveal the high water-uptake, impressive OH- conductivity of 175mScm-1 and mechanical robustness simultaneously, which overcomes the commonly existed dilemma between ion conductivity and mechanical property. Remarkably, the flexible zinc-air batteries assemble with biomass SSEs deliver an exceptional cycle lifespan of 310h and power density of 126mWcm-2. The design methodology for water and ion channels opens a new avenue to design high-performance SSEs for batteries.

Discrimination of Aspartic and Isoaspartic Acid Residues in Peptides by Tandem Mass Spectrometry with Hydrogen Attachment Dissociation.

Long-lived proteins undergo chemical modifications that can cause age-related diseases. Among these chemical modifications, isomerization is the most difficult to identify. Isomerization often occurs at the aspartic acid (Asp) residues. In this study, we used tandem mass spectrometry equipped with a newly developed ion activation method, hydrogen attachment dissociation (HAD), to analyze peptides containing Asp isomers. Although HAD preferentially produces [cn + 2H]+ and [zm + 2H]+ via N-Cα bond cleavage, [cn + 58 + 2H]+ and [zm - 58 + 2H]+ originate from the fragmentation of the isoAsp residue. Notably, [cn + 58 + 2H]+ and [zm - 58 + 2H]+ could be used as diagnostic fragment ions for the isoAsp residue because these fragment ions did not originate from the Asp residue. The detailed fragmentation mechanism was investigated by computational analysis using density functional theory. According to the results, hydrogen attachment to the carbonyl oxygen in the isoAsp residue results in the Cα-Cβ bond cleavage. The experimental and theoretical joint study indicates that the present method allows us to discriminate Asp and isoAsp residues, including site identification of the isoAsp residue. Moreover, we demonstrated that the molar ratio of peptide isomers in the mixture could be estimated from their fragment ion abundance. Therefore, tandem mass spectrometry with HAD is a useful method for the rapid discrimination and semiquantitative analysis of peptides containing isoAsp residues.

Holed up, but thriving: Impact of multitrophic cryoconite communities on glacier elemental cycles

Cryoconite holes (water and sediment-filled depressions), found on glacier surfaces worldwide, serve as reservoirs of microbes, carbon, trace elements, and nutrients, transferring these components downstream via glacier hydrological networks. Through targeted amplicon sequencing of carbon and nitrogen cycling genes, coupled with functional inference-based methods, we explore the functional diversity of these mini-ecosystems within Antarctica and the Himalayas. These regions showcase distinct environmental gradients and experience varying rates of environmental change influenced by global climatic shifts. Analysis revealed a diverse array of photosynthetic microorganisms, including Stramenopiles, Cyanobacteria, Rhizobiales, Burkholderiales, and photosynthetic purple sulfur Proteobacteria. Functional inference highlighted the high potential for carbohydrate, amino acid, and lipid metabolism in the Himalayan region, where organic carbon concentrations surpassed those in Antarctica by up to 2 orders of magnitude. Nitrogen cycling processes, including fixation, nitrification, and denitrification, are evident, with Antarctic cryoconite exhibiting a pronounced capacity for nitrogen fixation, potentially compensating for the limited nitrate concentrations in this region. Processes associated with the respiration of elemental sulfur and inorganic sulfur compounds such as sulfate, sulfite, thiosulfate, and sulfide suggest the presence of a complete sulfur cycle. The Himalayan region exhibits a higher potential for sulfur cycling, likely due to the abundant sulfate ions and sulfur-bearing minerals in this region. The capability for complete iron cycling through iron oxidation and reduction reactions was also predicted. Methanogenic archaea that produce methane during organic matter decomposition and methanotrophic bacteria that utilize methane as carbon and energy sources co-exist in the cryoconite, suggesting that these niches support the complete cycling of methane. Additionally, the presence of various microfauna suggests the existence of a complex food web. Collectively, these results indicate that cryoconite holes are self-sustaining ecosystems that drive elemental cycles on glaciers and potentially control carbon, nitrogen, sulfur, and iron exports downstream.

Ultrasmall Fe3O4 nanoparticles self-assembly induced dual-mode T1/T2-weighted magnetic resonance imaging and enhanced tumor synergetic theranostics

Individual theranostic agents with dual-mode MRI responses and therapeutic efficacy have attracted extensive interest due to the real-time monitor and high effective treatment, which endow the providential treatment and avoid the repeated medication with side effects. However, it is difficult to achieve the integrated strategy of MRI and therapeutic drug due to complicated synthesis route, low efficiency and potential biosafety issues. In this study, novel self-assembled ultrasmall Fe3O4 nanoclusters were developed for tumor-targeted dual-mode T1/T2-weighted magnetic resonance imaging (MRI) guided synergetic chemodynamic therapy (CDT) and chemotherapy. The self-assembled ultrasmall Fe3O4 nanoclusters synthesized by facilely modifying ultrasmall Fe3O4 nanoparticles with 2,3-dimercaptosuccinic acid (DMSA) molecule possess long-term stability and mass production ability. The proposed ultrasmall Fe3O4 nanoclusters shows excellent dual-mode T1 and T2 MRI capacities as well as favorable CDT ability due to the appropriate size effect and the abundant Fe ion on the surface of ultrasmall Fe3O4 nanoclusters. After conjugation with the tumor targeting ligand Arg-Gly-Asp (RGD) and chemotherapy drug doxorubicin (Dox), the functionalized Fe3O4 nanoclusters achieve enhanced tumor accumulation and retention effects and synergetic CDT and chemotherapy function, which serve as a powerful integrated theranostic platform for cancer treatment.

Incorporation of Three Different Optical Trains into the IR-MALDESI Mass Spectrometry Imaging Platform to Characterize Artemisia annua.

Artemisinin is the leading medication for the treatment of malaria and is only produced naturally in Artemisia annua. The localization of artemisinin in both the glandular and non-glandular trichomes of the plant makes it an ideal candidate for mass spectrometry imaging (MSI) as a model system for method development. Infrared matrix-assisted laser desorption electrospray ionization MSI (IR-MALDESI-MSI) has the capability to detect hundreds to thousands of analytes simultaneously, providing abundance information in conjunction with species localization throughout a sample. The development of several new optical trains and their application to the IR-MALDESI-MSI platform has improved data quality in previous proof-of-concept experiments but has not yet been applied to analysis of native biological samples, especially the MSI analysis of plants. This study aimed to develop a workflow and optimize MSI parameters, specifically the laser optical train, for the analysis of Artemisia annua with the NextGen IR-MALDESI platform coupled to an Orbitrap Exploris 240 mass spectrometer. Two laser optics were compared to the conventional set up, of which include a Schwarzschild-like reflective objective and a diffractive optical element (DOE). These optics, respectively, enhance the spatial resolution of imaging experiments or create a square spot shape for top-hat imaging. Ultimately, we incorporated and characterized three different optical trains into our analysis of Artemisia annua to study metabolites in the artemisinin pathway. These improvements in our workflow, resulted in high spatial resolution and improved ion abundance from previous work, which will allow us to address many different questions in plant biology beyond this model system.

Extraordinary synergy on 3D hierarchical porous Co-Cu nanocomposite for catalytic elimination of VOCs at low temperature and high space velocity

It is still a challenge to develop hierarchically nanostructured catalysts with simple approaches to enhance the low-temperature catalytic activity. Herein, a set of mesoporous Co-Cu binary metal oxides with different morphologies were successfully prepared via a facile ammonium bicarbonate precipitation method without any templates or surfactants, which were further applied for catalytic removal of carcinogenic toluene. Among the catalysts with different ratios, the CoCu0.2 composite oxide presented the best performance, where the temperature required for 90% conversion of toluene was only 237°C at the high weight hour space velocity (WHSV) of 240,000 mL/(gcat·hr). Meanwhile, compared to the related Co-Cu composite oxides prepared by using different precipitants (NaOH and H2C2O4), the NH4HCO3-derived CoCu0.2 sample exhibited better catalytic efficiency in toluene oxidation, while the T90 were 22 and 28°C lower than those samples prepared by NaOH and H2C2O4 routes, respectively. Based on various characterizations, it could be deduced that the excellent performance was related to the small crystal size (6.7 nm), large specific surface area (77.0 m2/g), hollow hierarchical nanostructure with abundant high valence Co ions and adsorbed oxygen species. In situ DRIFTS further revealed that the possible reaction pathway for the toluene oxidation over CoCu0.2 catalyst followed the route of absorbed toluene → benzyl alcohol → benzaldehyde → benzoic acid → carbonate → CO2 and H2O. In addition, CoCu0.2 sample could keep stable with long-time operation and occur little inactivation under humid condition (5 vol.% water), which revealed that the NH4HCO3-derived CoCu0.2 nanocatalyst possessed great potential in industrial applications for VOCs abatement.

Cluster size distributions, electronic characteristics and geometric structures of mixed cationic clusters of cesium and sulfur hexafluoride doped in helium

Mass Spectrometry has emerged as a valuable technique for investigating molecular cluster characteristics, including size distributions, compositions, stabilities and reactivity. In this study, we present a mass spectrometric analysis of cesium Cs mixed with sulfur hexafluoride S F 6 clusters, denoted as [ Cs ] n [ S F 6 ] m + , encapsulated within helium nanodroplets HNDs. Our analysis involved precise evaluation of mass spectra and calculating ion abundances taking into account the isotope patterns of ions. Additionally, we examined geometrical structures and stabilities of these molecules along with their corresponding highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gaps. This finding sheds light on the fundamental properties and behaviour of mixed molecular clusters, offering insights into their potential applications and interactions.

Direct infusion mass spectrometric analysis of ephedrine and pseudoephedrine

For thousands years Ephedrae herba has been used in traditional Chinese herbal medicine. Its main bioactive constituents are ephedrine and pseudoephedrine. Nowadays, these alkaloids have found application in various clinical treatments, as sports-enhancing drugs and for the illicit production of amphetamine-like drugs. Ephedrine and pseudoephedrine are diastereomers, and because of their high polarity and similar pKa values, their chromatographic separation may be a challenge. In this study a possible application of direct infusion mass spectrometry and direct infusion tandem mass spectrometry has been proposed for differentiation of ephedrine and pseudoephedrine as well as the relative determination of the contents of these compounds in a mixture. At low collision energy condition, the ratio of relative abundances of ions [M+H–H2O]+ and [M+H]+ permit distinction of the analyzed diastereomers, and enable evaluation of their relative content in a mixture with no need of chromatographic separation. The performed quantum chemical calculation have shown that protonated pseudoephedrine contains stronger hydrogen bond than protonated ephedrine, which can justify the observed higher relative abundance of ion [M+H–H2O]+ in the mass spectrum of pseudoephedrine, in comparison to that of ephedrine.