Intense Ion Research Articles

Double-Helix Electrode Ion Funnel: A New Ion Funnel Design with an Extended Mass Range.

The development of an atmospheric pressure interface (API) with a high ion transfer efficiency and wide mass range is advantageous for the performance improvement of mass spectrometry (MS) instruments. In this work, a novel ion guide, namely, the double-helix electrode ion funnel (DHE-IF), has been developed to enhance the ion transmission over a wide mass range in the rough vacuum region. The DHE-IF consists of two funnel-shaped helix electrodes. There are almost no potential "traps" along the central axis of DHE-IF due to the continuous double-helix electrode structure compared to the stacked ring ion funnel. The electrode design of the DHE-IF assembly was guided by ion trajectory simulations. After being fabricated, DHE-IF was integrated into an ESI-TOF-MS platform for tests. A conventional stacked ring ion funnel (IF) was also tested for comparison. The experimental results showed that DHE-IF extended the transmission window of the IF and improved the efficiency of the simultaneous transferring of low and medium m/z ions. In addition, the intensities of caffeine ions (m/z = 195) and reserpine ions (m/z = 609) were enhanced by more than 50% and 10%, respectively. These values were compared with the results obtained by the IF. The DHE-IF is expected to be widely used as an ion import device in MS instruments, which is due to its improved performance and advantages in, e.g., integration and power supply design.

Sequential dissociation of ionized benzonitrile: New pathways to reactive interstellar ions and neutrals

Since benzonitrile’s discovery in the interstellar medium (ISM) in 2018, several studies have explored the strongest unimolecular dissociations of its radical cation ( C6H5CN^ ). However, sequential dissociation processes, which become important when ionization occurs with significant excess energy transfer, have received almost no attention to date. The present metastable dissociative ionization experiments reveal 14 different dissociations, of which 11 have never been observed before. Nine of these new reactions involve the dissociation of a fragment ion. A notable result shows that C4H2^ production (the second most intense fragment ion in conventional mass spectra without metastable dissociation analysis) derives from sequential dissociation via C6H4^ as well as from the previously reported unimolecular dissociation of C6H5CN^ . Furthermore, our experiments demonstrate new pathways that produce astrochemically important neutrals including HCN CNH and CN^ as well as revealing CH^ and C3H^ production from ionized benzonitrile for the first time. In addition to the metastable dissociation experiments, we applied density functional theory to calculate two sequential dissociation routes and report the results of our detailed analysis of the peak shapes in a conventional mass spectrum of benzonitrile. The latter enabled the dominant ion to be identified in peaks with nearest-integer m/z values that match two conceivable ions. The present identification of C6H2N+ production using this approach allows its presence in the ISM to be inferred for the first time. This paper extends our understanding of how the dissociative ionization of benzonitrile can contribute to the abundances of radicals and other reactive species in interstellar environments.

Direct Implementation of MSn Using Frequency Scanning Collision Induced Dissociation in a Digital Ion Trap Mass Spectrometer.

Tandem mass spectrometry (MSn) is one of the most effective methods to obtain the structures of organic molecules, enabling the observation of multigenerational ion fragments. Collision-induced dissociation (CID) is currently the most mature technique for mass spectrometry analysis. Ion trap mass spectrometry (ITMS) is favored for on-site detection field, due to its ability of MSn analysis with a single trap and its small size. However, conventional MSn analysis in ITMS requires repeated isolation and excitation processes multiple times, causing high complexity of the entire scanning process. Additionally, the fragment ion detection in ITMS is limited by low-mass cutoff (LMCO) and the weak fragmentation yield. In this study, a method named reverse scanning-collision induced dissociation (RS-CID) is proposed, which involves increasing RF and AC frequencies while maintaining RF voltage constant during the CID process. Twelve representative illegal drugs were analyzed adopting this method, enhancing the intensities of low-mass fragment ions compared to conventional dissociation method. Moreover, experimental results with ketamine and methamphetamine show that RS-CID effectively reduces the LMCO effect and slightly improves CID efficiency. It also enables direct acquisition of their multigeneration fragment ions spectra in a single sequence of ion injection, cooling, isolation, RS-CID, cooling, mass scanning and empty. The experiments to distinguish between the isomers ab-4en-pinaca and adb-3en-butinaca as well as the isomeric compounds 5f-cumyl-pegaclone and cumyl-pipetinaca were also successful by this method. In summary, RS-CID enables MSn analysis in a single sequence and improves the low-mass fragment ions intensity. It can simplify workflows, achieve faster analysis and provide more valuable mass spectral information.

Ionization Characteristics of Glycan Homologues in Various Modes of Electrospray.

Fluorescence labeled glycan homologous mixtures were quantified using fluorescence and then used to evaluate ionization performances in electrospray ionization at micro, nano, and femto flow modes. nanoESI produced higher (2+ and 3+) charged ions adducted with sodium and calcium. In comparison, femtoESI was found to favor the generation of [M + H]+ ions against metal adducts, even with nonvolatile salts up to 1 mM for NaCl and 100 μM for CaCl2. For labeled glucose homopolymer (GHP) glycans, nanoESI and femtoESI had 0.81 and 3 nM detection limits, respectively. With LC separation and a much higher flow rate, conventional microflow ESI detected all glycans with 10-fold lower concentrations. Overall, nanoESI had the optimum uniformity in the relative ionization efficiency (RIE). When summing up intensities of analyte ions formed with all charge carriers, the RIE of the midsized glycans (10 to 16 glucose units) appear to be uniform (RIE 95%-105%). For the smaller (1-5 glucose units) glycan components, femtoESI provided better uniformity than nanoESI and conventional ESI. For the labeled IgG N-glycans, the impact of chemical structure on the ionization efficiency was revealed by the strong correlation between their RIE trends in different ionization modes.

Перенос энергии возбуждения в комплексах европия с доксициклином в присутствии мицелл поверхностно-активных веществ и наночастиц серебра

Doxycycline is a broad-spectrum tetracycline antibiotic used to treat infections in humans and in veterinary medicine as a prophylactic drug and growth stimulant. For this reason, residual amounts of antibiotics in milk, meat and other food products can cause resistance and the development of allergies. In this regard, constant monitoring of residual contents of tetracyclines in food products, environmental objects, and biological fluids is required. The purpose of this work was to study the effect of spherical silver nanoparticles and surfactant micelles on the intensity of sensitized fluorescence of europium ion complexes with doxycycline and to develop a new sensitive and simple method for the fluorimetric determination of doxycycline in solutions. As a result of the simultaneous influence of the energy of an external excitation source and the surface plasmon resonance of silver nanoparticles on doxycycline, the intensity of its fluorescence increases. The probability of the ligand transition to the excited state increases significantly, which contributes to the most efficient implementation of intramolecular excitation energy transfer in the Eu3+ complex with doxycycline. We have shown that in the presence of silver nanoparticles and Eu3+ ions, the fluorescence intensity of an analytical system containing doxycycline increases 125 times. In the presence of the nonionic surfactant Tween-80, the sensitized fluorescence signal of the Eu3+ chelate with doxycycline increases by more than 19 times. Solubilization of the components of the analytical reaction into micelles of surfactants helps to change their protolytic properties, dehydration, increase the stability of the complexes, and the efficiency of intramolecular energy transfer. In the combined presence of Tween-80 surfactant micelles and silver nanoparticles, an additional 27-fold increase in the fluorescence intensity of the metal ion chelate with doxycycline is observed. Based on the conducted research, a method for the fluorimetric determination of doxycycline using Tween-80 micelles, silver nanoclusters and Eu3+ ions in natural water has been proposed. The range of detectable concentrations is 1.0·10-7–1.0·10-5 M, detection limit (Limit of Detection) 6.0·10-8М (3 σ). The correctness of the definition has been controlled by the “entered–found” method.

Temporal kinetics of serum amyloid A (SAA) concentration and identification of SAA isoforms in blood and synovial fluid of horses with experimentally induced septic arthritis, non-septic synovitis, and systemic inflammation.

Prompt diagnosis of equine septic arthritis is crucial for successful treatment. Serum amyloid A (SAA) has been suggested as a reliable biomarker. However, we previously found that synovial fluid SAA increases in nonaffected joints of horses with septic arthritis. We hypothesized that systemic SAA may leak into the nonaffected joints. If this is the case, we also hypothesized that locally produced joint SAA isoforms may be better candidates for septic arthritis biomarkers. Thus, our objectives were 1) to evaluate the temporal kinetics of systemic and synovial fluid SAA in horses with septic arthritis (n = 5), non-septic synovitis (n = 5), and systemic inflammation (n = 5), examining both affected and contralateral joints; and 2) investigate putative locally produced joint SAA isoforms and detect amino-acid differences between them. We confirmed that SAA increases significantly in synovial fluid in nonaffected joints of horses with systemic inflammation (≤352 mg/L), as well as in contralateral nonaffected joins in horses with septic arthritis (≤1,830 mg/L) compared to baseline at time 0 (<0.2 mg/L). We also identified a putative locally produced joint SAA peptide in synovial fluid (FGDSGHGAADSR) that differed in 1 amino acid from 2 systemic peptides found both in plasma and synovial fluid. The putative joint SAA isoform was present in joints of horses with both septic arthritis and systemic inflammation (ion intensities 104-106). Thus, the increase of synovial fluid SAA may be both due to the leakage of SAA from serum into joints and local production of joint SAA isoforms.

A SOURCE OF INTENSE HELIUM ION FLOW BASED ON AN ARC DISCHARGE IN A MAGNETIC FIELD

The work is dedicated to the investigation of a source of intense ion flow based on a low-pressure arc discharge in a longitudinal magnetic field. The obtained helium ion flows are characterized by a total current of up to 0.75 A, a current density of up to 10 A/cm², and a specific power at the collector of up to 6.4 kW/cm². The dependence of the ion flow on experimental parameters and conditions was studied. This ion flow source can be applied in ion-plasma technology processes.

Transforming waste into multifunctional nanomaterials: Mg-doped carbon dots from cow dung for Y(III) detection and biomedical applications

Rare earth metal Yttrium (Y3+) plays a vital role in many electronic devices however, discarding these devices eventually contaminates the environmental sources. Herein, we have developed a Mg-doped carbon dots (M-CDs) as a fluorescent probe for selective and sensitive determination of Y3+ in water bodies. The M-CDs having maximum emission at 420 nm upon 310 nm excitation with 20 % quantum yield and which was synthesized from upcycling of agricultural waste i.e., cow dung by simple carbonization followed by hydrothermal method. M-CDs were confirmed using different analytical and characterization techniques as well as stable in different pH and ionic strength solutions. The M-CDs was highly selective towards Y3+ ions over different metal ions with significant blue shift. This fluorescent probe performs a good linear relationship between the different concentrations of Y3+ ion and fluorescence intensity (R2 = 0.99) within the range of 0.2 to 20 μg/mL with a detection limit of 0.019 µg/mL. The study indicates quenching of Y3+ was result of dynamic quenching and the Inner Filter Effect (IFE) effect. Also, the cytotoxicity of M-CDs was checked via CAM assay and significant growth in blood vascularization with healthy growth of chick embryo confirmed the M-CDs were biocompatible. The nontoxic M-CDs was employed for MCF-7 breast cancer cell imaging which gives bright blue fluoresce under UV light excitation. Further, aiming to a circular economy approach the residual carbon remaining after hydrothermal was used as reactivated carbon for the abatement of environmental pollutants. The sustainable, cost-effective and agricultural waste-derived Mg-doped CDs have potential applications in analytical, environmental, forensic as well as biomedical fields.

Serially coupled columns enhance rapid separation and predictive interaction understanding of 93 fentanyl analogs

BackgroundThe simplicity of synthesis methods has facilitated the illegal manufacture of various fentanyl analogs, leading to numerous fatal overdoses worldwide, particularly in North America. Fentanyl analogs with similar structures are difficult to distinguish due to their fragmentation patterns, making separation using chromatography essential. Additionally, because fentanyl analogs are lethal even in trace amounts, they are easily smuggled, and commonly used fentanyl test strips often fail to detect them due to their low sensitivity. Therefore, the urgent need for analytical methods that can simultaneously identify multiple analogs and swiftly detect them at low concentrations. ResultsIn this study, liquid chromatography-tandem mass spectrometry was conducted to screen 93 types of fentanyl analogs among the illegal fentanyl substances. The phenyl-hexyl columns enhance fentanyl analog separation through strong π–π interactions. The serially coupled column system increased the separation efficiency and mitigated peak distortion, particularly those of polar fentanyl analogs. The selectivity varied significantly, depending on the interactions with the combined columns. The phenyl-hexyl column's superior ability to predict fentanyl analog interactions based on molecular structure was confirmed by retention factor analysis. The resolution of fentanyl isomers increased significantly when methanol was used instead of acetonitrile as an organic modifier in the mobile phase. The approach was validated by determining the limits of detection and quantification, specificity, detection capability, recovery, and relative ion intensity. SignificanceThe fentanyl analogs, including 23 sets of isomeric and isobaric compounds, were analyzed via separation using a phenyl-hexyl column serially coupled with a cyano column. The serially coupled column system increased the separation efficiency and mitigated peak distortion, particularly those of polar fentanyl analogs. The proposed strategy can be adopted in exploring methods of effectively separating mixtures with diverse properties, aiding the prevention of drug abuse and bolstering public health and safety efforts.

Mapping Li Concentration Gradients across Battery Cathodes

Lithium-ion batteries (LIBs) are playing an increasingly important role in enabling the transition to a low-carbon global economy, in electric vehicle and grid storage applications. Despite increasing LIB ubiquity, there remains gaps in our understanding of how to optimize further LIB electrode design and structure, and how to achieve such designs in practice and at scale without excessive trial-and-error experimentation. For example, thicker electrodes are desirable for improved volumetric capacity but particularly during rapid charging and discharging cycles, a significant through-electrode thickness Li ion concentration gradient in the electrolyte builds up. This leads to a spatially varying concentration overpotential that in turns leads to uneven utilization of the active material, resulting in diminished capacity and accelerated degradation. Although models of electrode dynamics can help qualitatively to understand concentration polarization effects as a function of electrode design, there are few practical experimental tools to visualize or resolve Li-ion concentration gradients in practice. For example, the widely-used energy dispersive X-ray spectroscopy (EDS) in a scanning electron microscopy cannot resolve elements with very low atomic number such as Li.In this presentation we describe the development of a methodology to visualize Li-ion concentration gradients across a range of electrodes based on secondary ion mass spectroscopy (SIMS). We combine SIMS with EDS to collect elemental maps of all principle LIB electrode elements in a single workflow, which is also extended to 3D by further combining with a plasma field ion microscope (P-FIB) capability. We apply the new methodology for LIB cathodes based on LiFePO4 (LFP) and LiMn2O4 (LMO) that are at different state of overall charge, achieved at a range charging rates. The electrodes also span a range of thicknesses from 100 to 700 µm. We show how the approach can operate over cross-sections large enough to encompass all the electrode thickness while maintaining sufficient spatial resolution to capture key features of the local Li concentration. While EDS elemental maps, with appropriate calibration, can be correlated to local element concentration with good accuracy, SIMS spectra and specifically the intensity of the 7Li+ peaks cannot be readily related to local Li concentration since the yield of 7Li+ ion relates to additional factors, such as the local atomic environment, surface topology and more. We describe how we inter-relate the EDS and SIMS maps for non-Li elements to account for some of these features, and show how these reveals the underlying Li distributions. We consider how these measurements of the Li concentration in the solid particles of the electrode relate to the local state of charge, and the conditions in the electrolyte when charge/discharge was halted and the sample was retrieved from the cell for examination. Fine-scale variations in local 7Li+ ion intensity are also revealed and explained in terms of local microstructural features such as particle size, any particle cracking, the growth of secondary electrolyte interphase, etc.

Decreases in metabolic ATP open KATP channels and reduce firing in an auditory brainstem neuron: A dynamic mechanism of firing control during intense activity

Cartwheel (CW) neurons are glycinergic interneurons in the dorsal cochlear nucleus (DCN) that exhibit spontaneous firing, resulting in potent tonic inhibition of fusiform neurons. CW neurons expressing open ATP-sensitive potassium (KATP) channels do not fire spontaneously, and activation of KATP channels halts spontaneous firing in these neurons. However, the conditions that regulate KATP channel opening in CW neurons remain unknown. Here, we tested the hypothesis that fluctuations in metabolic ATP levels modulate KATP channels in CW neurons. Using whole-cell patch-clamp recordings in CW neurons from young rat brain slices (p17-22) with an ATP-free internal solution, we observed that the mitochondrial uncoupler CCCP hyperpolarized the membrane potential, reduced spontaneous firing, and generated an outward current, which was inhibited by the KATP channel antagonist tolbutamide. Additionally, a glucose-free external solution quickly activated KATP channels and ceased spontaneous firing. We hypothesized that intense membrane ion ATPase activity during strong depolarization would deplete intracellular ATP, leading to KATP channel opening. Consistent with this, depolarizing CW neurons with a 250 pA DC did not increase spontaneous firing because the depolarization activated KATP channels; however, the same depolarization after tolbutamide administration increased firing, suggesting that ATP depletion triggered KATP channel opening to limit action potential firing. These results indicate that KATP channels in the DCN provide dynamic control over action potential firing, preventing excessive excitation during high-firing activity.

Broiler breeder putative lipid biomarkers associated with sperm mobility.

Biomarkers indicative of sperm mobility in broiler breeders would provide the ability to screen for fertility potential, with a positive correlation established between sperm mobility and fertilization potential. This study characterized the lipidome of seminal plasma (SP), sperm cell (SC), and whole semen (WS) isolated from broiler breeder roosters with different sperm mobility phenotypes across key timepoints of the semen production cycle. WS samples were collected from five high mobility roosters and five low mobility roosters during early, mid, and late semen production, with SP separated from SC by centrifugation. Using multiple reaction monitoring (MRM) profiling, a total of 3241 lipid species were identified in rooster semen across ten lipid classes. Metaboanalyst 6.0 was used to analyze the relative ion intensity for each lipid species due to sperm mobility phenotype through a t-test and due to timepoint through a one-way ANOVA, with lipid ontology enrichment analysis performed using LION. Metaboanalyst 6.0 was also used to perform biomarker analysis for the sperm mobility phenotype in WS samples. Lipid class total abundance differed with sample type, sperm mobility phenotype, and timepoint. A total of 31, 99, and 112 lipid species were found to be different between low and high mobility males across timepoints in the SP, SC, and WS samples, respectively. Lipid ontology enrichment analysis revealed stark contrasts in lipid-based functions key to sperm survival, storage, and productivity between low and high sperm mobility phenotypes. Through biomarker analysis, 8 lipid species were identified as excellent sperm mobility biomarkers that could be detected in early and mid-semen production. Timepoint based changes in lipid species were unique to each sperm mobility phenotype, with low sperm mobility roosters exhibiting a larger number of lipid species changes over the semen production cycle in the SP and SC when compared to high sperm mobility roosters. This is the first study to characterize poultry semen lipidome using MRM profiling. The lipid species identified between low and high sperm mobility roosters could be utilized in the poultry industry as potential biomarkers of fertility potential, with the ability to screen for the economical trait of fertility potential early in semen production.

ALKALI ALCOHOLYSIS OF 2-PHENYL-gem-DICHLOROCYCLOPROPANE UNDER MICROWAVE RADIATION CONDITIONS

By alkaline alcoholysis of 2-phenyl-gem-dichlorocyclopropane, α-phenylacrolein acetals were synthesized under microwave irradiation (MWI) conditions: [1-(diethoxymethyl)vinyl]benzene, [1-(di-propyloxymethyl)vinyl]benzene, [1-(di- iso-propyloxymethyl)vinyl]benzene, [1-(dibutoxymethyl)vinyl]benzene, [1-(di-iso-butoxymethyl)-vinyl]benzene, {1-[bis(1-methylbutoxy)methyl]vinyl}benzene, [1-(dially-loxymethyl)vinyl]benzene, 1,1-[(2-phenylprop-1-en-3,3-diyl)bis(oxymethylene)]dibenzene. It was found that microwave radiation reduces the synthesis time by 70%, while the yield is more than 80%, and the selectivity of acetal formation is more than 90%. Using the method of competitive kinetics, it was established that primary alcohols such as ethanol, propanol and butanol are similar in activity. The structures of the obtained compounds were studied using nuclear magnetic resonance (NMR) and chromatography-mass spectrometry methods. The formation of acetals is proven by the presence of signals from the quaternary carbon atom in the region δс 142.35-146.49 ppm, and a doublet signal from protons at δн 5.01–5.71 ppm. and a singlet signal of the proton of the methine group in the region at 4.89-5.50 ppm. Analysis of the mass spectra of acetals showed the presence of maximum intensity of oxonium ions, due to α-, β-break relative to the oxygen atom. For the obtained acetals, the presence in the mass spectra of [M-H]+ cations, formed as a result of the release of a hydrogen radical from a molecular radical ion, was recorded. The peaks of [M-R]+ and [M-H]+ ions were inferior in intensity to [M-RO]+ cations. Most likely, this is explained by the stability of the [M-RO]+ cations relative to [M-C6H5C2H2]+ and [M-H]+, as well as the ease of eliminating RO• from the alkoxy group. In addition, for acetals of this type, the formation of a radical cation with m/z = 132 was observed, resulting from the release of the R radical from the second alkoxy group. Also, the mass spectra of acetals were characterized by the presence of a cation m/z = 77 and an intensity of 29-80%. Borisova Yu.G., Musin A.I., Voinov A.V., Spirikhin L.V., Raskil’dina G.Z., Sultanova R.M., Zlotskii S.S. Alkali alcoholysis of 2-phenyl-gem-dichlorocyclopropane under microwave radiation conditions. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 11. P. 15-21. DOI: 10.6060/ivkkt.20246711.7046.

Can fragment ion intensity be used for fatty acid sn-position determination of food phospholipids?

Fatty acid (FA) regio-position is critical information for the structures of both triglycerides and phospholipids in food products. Although lipase/phospholipase hydrolysis combined with TLC separation and GC analysis can be used to determine the overall sn-2 FA composition of triglycerides/phospholipids in food samples, it is much more challenging to pinpoint FA regio-position at the molecular species level. Currently, the most widely used method to obtain such information is based on the relative intensity of fragment ions generated in tandem mass spectrometry. The reliability of this approach was verified in this study using regio-pure phospholipid standards and by cross-validation with the Paternò–Büchi photochemical reaction. We have demonstrated that for food materials with widespread regioisomers, a standard calibration curve from regio-pure standards is needed to determine the proportion of each isomer, whereas fragment ion intensity can only be used to reveal the sn-position of FA in phospholipid molecules devoid of regioisomers.

Production of high intensity high charge state uranium ion beams in afterglow mode with advanced electron cyclotron resonance (ECR) ion sources.

To satisfy the requirement of heavy ion synchrotron for intense highly charged ion beams, a comprehensive study of the afterglow mode was performed with two advanced electron cyclotron resonance (ECR) ion sources, i.e., a second-generation ECR ion source (LECR4) and a third-generation ECR ion source (SECRAL-II). Intense pulsed uranium ion beams of highly charged states were produced with both ion sources (e.g., 58 eμA of 238U39+ in LECR4 and 124 eμA of 238U46+ in SECRAL-II). Compared to the beam intensity records obtained in continuous wave mode, the gain factor is up to ∼6. It was found that the optimum microwave pulse width and the decay time in SECRAL-II operating at 24GHz are obviously longer than those in LECR4 operating at 14.5GHz, aligning with a previous observation made with SECRAL-II ion source.

Accurate determination of matrix composition in Cd x Zn 1 − x O semiconductor material using MS-SIMS and ToF-SIMS methods

Abstract This study focuses on the method for determining the exact composition for Cd x Zn 1 − x O semiconducting material using secondary ion mass spectrometry. The calibration curve method is employed to establish a quantitative relationship between the intensity of secondary ions and the concentrations of elements in Cd x Zn 1 − x O thin films. Additionally, the study compares the relative sensitivity factors with the calibration curve method for determining the value of x in Cd x Zn 1 − x O . A comparison between the performances of Time of Flight and Magnetic Sector SIMS in analyzing Cd x Zn 1 − x O thin films is also presented. This approach aims to enhance the accuracy and reliability of quantitative analysis in SIMS for Cd x Zn 1 − x O thin films.

Effects of Hydrogen Dissociation During Gas Flooding on Formation of Metal Hydride Cluster Ions in Secondary Ion Mass Spectrometry.

The application of hydrogen flooding was recently shown to be a simple and effective approach for improved layer differentiation and interface determination during secondary ion mass spectrometry (SIMS) depth profiling of thin films, as well as an approach with potential in the field of quantitative SIMS analyses. To study the effects of hydrogen further, flooding of H2 molecules was compared to reactions with atomic H on samples of pure metals and their alloys. H2 was introduced into the analytical chamber via a capillary, which was heated to approximately 2200 K to achieve dissociation. Dissociation of H2 up to 30% resulted in a significant increase in the intensity of the metal hydride cluster secondary ions originating from the metallic samples. Comparison of the time scales of possible processes provided insight into the mechanism of hydride cluster secondary ion formation. Cluster ions presumably form during the recombination of the atoms and molecules from the sample and atoms and molecules adsorbed from the gas. This process occurs on the surface or just above it during the sputtering process. These findings coincide with those of previous mechanistic and computational studies.

Carafe enables high quality in silico spectral library generation for data-independent acquisition proteomics.

Data-independent acquisition (DIA)-based mass spectrometry is becoming an increasingly popular mass spectrometry acquisition strategy for carrying out quantitative proteomics experiments. Most of the popular DIA search engines make use of in silico generated spectral libraries. However, the generation of high-quality spectral libraries for DIA data analysis remains a challenge, particularly because most such libraries are generated directly from data-dependent acquisition (DDA) data or are from in silico prediction using models trained on DDA data. In this study, we developed Carafe, a tool that generates high-quality experiment-specific in silico spectral libraries by training deep learning models directly on DIA data. We demonstrate the performance of Carafe on a wide range of DIA datasets, where we observe improved fragment ion intensity prediction and peptide detection relative to existing pretrained DDA models.

Temperature Changes in Luminescence of Mixed Complexes of Terbium and Samarium with Organic Ligands Based on 2,2-bipyridyldicarboxamides

Solutions in acetonitrile of three mixed complexes of rare earth elements (terbium and samarium) with organic ligands with various pyridine substituents were studied in this work. The ratios of ligands and metals in the resulting complexes were determined, and the stability constants of samarium complexes were calculated using the spectrophotometric titration method. Measurements of absorption, emission and excitation spectra of luminescence, luminescence kinetics of solutions of mixed complexes of rare earth elements with an excess of metal relative to the ligand were carried out at various temperatures in the range 298–328 K. An increase of luminescence intensity of a samarium ion in complex upon heating has been discovered for the first time. The dependences of the luminescence quantum yield and lifetime of mixed complexes on temperature were obtained. A thermometric parameter — the ratio of the integral luminescence intensities of samarium and terbium ions — was proposed, and the temperature sensitivity coefficient of this parameter was determined for different complexes.

Bias disk boost technique for pulsed-operation electron cyclotron resonance ion sources

A simple, effective technique to increase the intensity of multiply charged ions has been developed for pulsed-operation electron cyclotron resonance ion sources (ECRISs). The technique is realized simply by applying an additional boost voltage of about −1 kV to a negative constant voltage on the bias disk. The technique can be applied to general ECRISs by adding electric devices to the bias disk circuit, such as a high-voltage power supply, a fast high-voltage switch, and a diode. The effect of the technique depends on the ion species, and we obtained a maximum ion intensity increase of 66% for O6+ compared with the conventional bias disk method. In particular, the technique can be applied to the existing pulsed-operation ECRISs used at a heavy-ion cancer therapy facility where multi-ion treatment with multiply charged oxygen and neon ions is planned to be introduced.