Ion Mass Research Articles

Experimental and Zero-dimensional Simulation Study of an Embedded Bismuth LaB6 Hollow Cathode

Experiments and zero-dimensional simulation were conducted to evaluate the discharge performance of an embedded bismuth LaB6 hollow cathode. The experimental results demonstrate that the embedded bismuth hollow cathode can operate in diode mode without any external heating, with a mass flow rate of approximately 0.21 mg/s. In Keeper-cathode mode, the discharge voltage for bismuth was slightly lower than that of xenon and exhibited strong stability, with a maximum discharge variation of less than 0.5 V at a discharge current of 2 A. The simulation results showed that at the same mass flow rate, the electron and ion densities in the insert region of the bismuth cathode were higher than those of xenon, whereas the opposite was true for the orifice region. Notably, at discharge currents below 4 A, the power deposition of bismuth in both the insert and orifice regions was lower than that of xenon, indicating reduced orifice erosion and effective self-heating of the insert at low current levels.

GC–MS-based metabolite fingerprinting reveals the presence of novel anticancer compounds in the microcolonial fungus Aureobasidium sp. TD-062 from the under-explored Thar Desert

Aureobasidium sp., strain TD-062, a micro colonial black yeast, was obtained as part of a screening program from the Thar Desert of India, which has been inadequately explored for novel microorganisms/bioactive metabolites. The anticancer activity of aqueous and organic solvent extracts of culture supernatant of TD-062 was investigated against A-375 myeloma and MCF-7 breast cancer cell lines. Following column chromatography, bioactive fractions were subjected to GC–MS analysis in two cycles. The GC–MS metabolite fingerprinting revealed 20 compounds belonging to various chemical groups. Further, based on observed and calculated mass ion spectra, retention time, and retention indices, many compounds could be considered novel. The second purification cycle resulted in three compounds- ATD-1, ATD-2 and ATD-3 with different calculated retention indices from that of the nearest matching compounds, squalene and tocopherol. In silico prediction study of their ADMET profiles, suggests that these new compounds have a suitable contour for use as safe anticancer drugs, without the toxicity normally associated with anticancer compounds.

A simplified coaxial ion trap mass analyzer: Characterization of the simplified toroidal ion trap with a rectilinear ion guide

A new miniature coaxial ion trap mass analyzer with a rectilinear ion guide has been constructed using a combination of planar and cylindrical electrodes. The results reported here focus on characterizing the performance of the rectilinear ion guide and simplified toroidal ion trap components. The simplified toroidal ion trap was found to have an ion capacity in excess of 105 ions and mass spectral resolution of 0.5–0.6 when used as a mass analyzer. The ion storage efficiency within the toroidal trapping region was evaluated and found the stored ion population decreased exponentially with storage time. Ion losses depended slightly on the stored βz condition. Ion losses within the toroidal region are attributed primarily to field instabilities at the intersection point of the two components while charge exchange reactions were observed but considered a minor loss mechanism. The ability to mass selectively ejection ions of a specific mass from the toroidal trapping region was characterized and found to approach 100 % efficiency under appropriate ejection conditions.

Confined mass transport in two-dimensional capillary

Abstract Over the past decade, nanofluidics has undergone significant expansion, propelled by advances in crafting artificial channels at nanometric and sub-nanometric scales with diverse geometries. Central to this domain, two-dimensional capillaries have risen as a pivotal research platform, marked by their angstrom-level precision, unparalleled wall surface smoothness, and clearly defined surface charge states. Their advent has profoundly deepened our understanding of mass transport dynamics, spanning gases, water molecules, and ions, shedding light on the complex interactions among various influencing factors and revealing a range of previously undiscovered physical phenomena. This review delves into the development of 2D capillaries, the principal fluid transport phenomena observed within, and the critical elements that affect these processes. We also touch on a fascinating discovery - the quantum liquid friction seen in water moving over carbon surfaces. In anticipation of future explorations in nanofluidics, we envision a trajectory aimed at emulating the efficiency levels of biological protein channels, setting the stage for a new era of scientific inquiry and technological innovation.

Mercury’s plasma environment after BepiColombo’s third flyby

Understanding Mercury’s magnetosphere is crucial for advancing our comprehension of how the solar wind interacts with the planetary magnetospheres. Despite previous missions, several gaps remain in our knowledge of Mercury’s plasma environment. Here, we present findings from BepiColombo’s third flyby, offering a synoptic view of the large scale structure and composition of Mercury’s magnetosphere. The Mass Spectrum Analyzer (MSA), Mass Ion Analyzer (MIA), and Mass Electron Analyzer (MEA) on the magnetospheric orbiter reveal insights, including the identification of trapped energetic hydrogen (H+) with energies around 20 keV e−1 evidencing a ring current, and a cold ion plasma with energies below 50 eV e−1. Additionally, we observe a Low-Latitude Boundary Layer (LLBL), which is a region of turbulent plasma at the edge of the magnetosphere, characterized by bursty ion enhancements, indicating an ongoing injection process in the duskside magnetosphere flank. These observations during cruise phase provide a tantalizing glimpse of future discoveries expected from the Mercury Plasma Particle Experiment (MPPE) instruments after orbit insertion, promising broader impacts on our understanding of planetary magnetospheres.

SiO2 sputtering by low-energy Ar+, Kr+, and Xe+ ions in plasma conditions

Modern plasma technologies applied for nm-size devices require localizing ions’ impact within up to atomic layer to avoid uncontrollable damage of underlying structures. The decrease in energy of ions incident on a surface is one of the ways to achieve this. In this work, SiO2 sputtering by Ar+, Kr+, and Xe+ ions at energies of 20–200 eV was studies in the low-pressure ICP-discharge at a plasma density typical for plasma processing. The rf-bias waveform tailoring due to high discharge asymmetry allowed generating and controlling ion narrow energy spectrum with FWHM 5±2 eV. Real time in-situ control over ion composition and flux as well as sputtering rate provided accurate determination of the SiO2 sputtering yield, . It is shown that at ion energy above ∼70 eV, the “classical” kinetic sputtering mechanism prevails. In this case, rapidly grows with ion energy, while decreasing with the decrease in ion mass. Below ∼70 eV, the change of is strongly slow down while the sputtering yield still stays high enough (>10-3), demonstrating the plasma impact on the sputtering mechanism. The obtained trends of under the plasma exposure are discussed in light of possible SiO2 surface modification studied by AFM and angular XPS analysis.

Isomeric Speciation of Bisbenzoxazine Intermediates by Ion Spectroscopy and Ion Mobility Mass Spectrometry.

Bisbenzoxazines (BisBz) are a relevant model for the diverse bifunctional benzoxazines that are used to increase the polybenzoxazines cross-linking extensions and modulate the final resin properties for various usages. The presence of side products and intermediates during monomer formation can influence the resin characteristics by inducing chain termination and ramifications, affecting the polymerization and cure processes. This work investigated the diverse isomeric intermediates and side products that are present during the BisBz formation from bisphenol A, aniline, and formaldehyde by ion mobility coupled to tandem mass spectrometry (MS/MS) and ion spectroscopy techniques. The species detected in this work suggest that these multifunctional phenols open diverse concurrent reaction pathways based on two main reactive steps: (i) the imine/iminium phenol attack to form a phenylamino intermediate and (ii) the formaldehyde attack followed by dehydration to form the oxazine ring. The species observed also support previous studies of the benzoxazine formation mechanism and showcase the application of advanced analytical techniques in studying complex chemical systems.

Rapid discovery of natural antioxidants in Hypericum japonicum: Dual roles of the liquid phase mobile phase as extraction and separation solvent

Hypericum japonicum is a traditional folk medicine with various bioactivities such as hepatoprotective, antioxidant, and anti-tumorous. The antioxidant effect of H. japonicum is one of the most prominent effects due to its responsibility for many of its activities. To clarify active natural substance, the antioxidant properties of H. japonicum were preliminarily assessed by ferric reducing–antioxidant power (FRAP), 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and Oxygen radical absorbance capacity (ORAC), as well as superoxide dismutase (SOD). Then, a straightforward and effective method named online liquid extraction-high performance liquid chromatography combined with ABTS antioxidant assay and mass spectrometry (OLE-HPLC-ABTS/Q-TOF-MS) was developed to swiftly and directly discover the antioxidants in H. japonicum. Using mobile phase as extraction and separation reagent, coupled with online activity analysis and compounds identification by high-resolution MS, the online system enables rapid screening of natural antioxidant bioactives from complex mixture. By using it, a total of 9 compounds including flavonoids and phenolic acids characterized by retention time, precise mass, and fragmentation ions in MS/MS spectra showed antioxidant action. Finally, the antioxidant and SOD activity of main found active compounds were validated by in vitro experiment assay and molecular docking. In summary, these results suggested that H. japonicum could be considered as a potential source of natural antioxidants, and the online integrated system might become a promising candidate for the natural antioxidants discovery in the future.

Electrical-Modulated Flexible Acoustic Metamaterial: Enhancing Low-Frequency Absorption via an Ionic Electroactive Polymer.

The growing concern over low-frequency noise pollution resulting from global industrialization has posed substantial challenges in noise attenuation. However, conventional acoustic metamaterials, with fixed geometries, offer limited flexibility in the frequency range adjustment once constructed. This research unveiled the promising potential of ionic electroactive polymers, particularly ionic polymer-metal composites (IPMCs), as a superior candidate to design tunable acoustic metamaterial due to its bidirectional energy conversion capabilities. The previously perceived limitations of the IPMC, including slow reaction and high energy expenditure, owning to its inherent sluggish intermediary ionic mass transport process, were astutely leveraged to expedite the attenuation of low-frequency sound energy. Both our experimental and simulation results elucidated that the IPMC can generate voltage potentials in response to acoustic pressure at frequencies significantly higher than those previously established. In addition, the peak absorption frequency can be effectively shifted by up to 45.7% with the application of a 4 V voltage. By further integration with a microperforated panel (MPP) structure, the developed metamaterial absorbers can achieve complete sound absorption, which was continuously tunable under minimal voltage stimulation across a wide frequency spectrum. In addition, a microslit structure IPMC metamaterial absorber was designed to realize modulation of the perforation rate, and the absorption peak can be shifted by up to 79.2%. These findings signify a pioneering application of ionic intelligent materials and may pave the way for further innovations of tunable low-frequency acoustic structures, ultimately advancing the pragmatic deployment of both soft intelligent materials and acoustic metamaterials.

Fingerprinting alkaloids for traceability: Semi-untargeted UHPLC-MS/MS approach in raw lupins as a case study

Lupin seeds are recognized for their nutritional value and potential health benefits, but they contain also a significant amount of alkaloids, an anti-nutritive class of compounds, which vary significantly in composition within and between species due to environmental factors. In this study, we developed a predictive multi-experiment approach using ultra-high performance liquid chromatography coupled with triple quadrupole with linear ionic trap tandem mass spectrometry (UHPLC-QqQ-LIT-MS/MS) for comprehensive alkaloid profiling and geographical classification of Lupinus albus L. samples originating from four different Italian regions. Six targeted quinolizidine alkaloids were detected and 21 other alkaloids were putatively identified. Hierarchical Cluster Analysis (HCA) and partial least squares discriminant analysis (PLS-DA) were applied to explore the data structure and successfully classify samples according to their geographical origin. The data demonstrate the efficacy of the developed approach in providing valuable insights in alkaloid profiles of lupin seeds and their potential as markers for geographical traceability.

An advancement of the gravimetric isotope mixture method rendering the knowledge of the spike purity superfluous

The gravimetric isotope mixture method is the primary method to determine absolute isotope ratios. This method, however, depends on the existence of suitable spike materials and knowledge of their purities. Determining the purity of the spikes can be tedious and labour-intensive. In this publication, an advancement of the gravimetric isotope mixture method, rendering the determination of the purity of the spike materials unnecessary, is presented. The advancement combines mass spectrometry and ion chromatography leading to an approach being independent of the purity of the spike materials. In the manuscript the mathematical background and the basic idea of the novel approach are described using a two-isotope system like copper or lithium.Graphical abstract

The linear Paul Trap's Confined Stability Area for 40Ca+ Ions

تقدم تكنولوجيا الكم طرقًا حسابية واتصالات ومحاكاة وقياسًا جديدة. تحتاج أجهزة الكمبيوتر التقليدية إلى المساعدة في حل المشكلات المهمة مثل التحليل بسبب الزيادات الهائلة في وقت الحساب. ومع ذلك، تستخدم أجهزة الكمبيوتر الكمومية ميكانيكا الكم لحجم المشكلة الأسي الفرعي ويمكنها محاكاة الطبيعة على المستوى الكمي. يهتم العلماء بشكل متزايد بتطوير أجهزة الكمبيوتر الكمومية باستخدام ذرات متأينة مفردة في مصائد باولي. تمثل الحالة الأساسية لكل أيون أقل قيمة ممكنة للبت الكمي. تم استخدام الأيونات المحتجزة 40Ca+ في إحدى الدراسات كمثال على الكيوبت الكمومي. تم استخدام برنامج MATLAB على العوامل النموذجية التي تؤثر على الحالة المقيدة وتأثيراتها. يجب أن تكون الحلول مستقرة في كلا الاتجاهين، مما يتطلب حصرًا ثلاثي الأبعاد لمعادلة ماثيو. تؤثر المتغيرات على المسافة من مركز المصيدة لنهاية القطب، وجهد UDC، وكتلة الأيون، والترددات الراديوية. تم استخدام جهد متغير للتحكم وإظهار تأثيره على سلسلة محددة من الأيونات المحاصرة. يهدف هذا البحث إلى فهم أفضل للظروف المثلى للحجز وحركة الأيونات من الحالة (4S1/2) إلى الحالة (4P1/2) بالرنين. تخضع الحالة الكمومية للتعديل والتغيير، مما يجعلها أداة واعدة لحل المشكلات المعقدة.

MOFs/MXene nano-hierarchical porous structures for efficient ion dynamics

Nature's various hierarchical structures exhibit exceptional performance in enhancing mass transport. However, how to bionic nano-hierarchical structures to enhance ion dynamics and achieve charge regulation is a significant challenge. Herein, a nano-hierarchical porous hybrid membrane inspired by nature was designed by integrating 1D metal-organic frameworks (MOFs) on the 2D MXene substrate utilizing MOF nanoparticles with tailorable positive and negative surface charges. The synergistic effects of the bioinspired nanohierarchical porous structure and surface charge interactions significantly enhance the performance and stability of the nanoconfined membrane, as corroborated by experimental characterizations and theoretical simulations. As a result, the optimized nanohierarchical porous membrane exhibits high a cation selectivity of 0.95, an outstanding power density of 35.04 W m−2, and excellent stability over one month. Synergizing enhanced mass transport and ion dynamics in nano-hierarchically structured materials with tailored charge improves osmotic power generation efficiency and benefits logic circuits with controlled charge transport.

Towards a precise measurement of 157Tb nuclear decay data: Sample purification using resonance ionization mass spectrometry

In nuclear physics, 157Tb emerges as a prime candidate for experiments aimed at elucidating neutrino mass constraints and at searching for sterile neutrinos. Despite its importance, 157Tb exhibits highly uncertain values for its nuclear decay properties. A significant challenge in many efforts to measure such data lies in the simultaneous undesired presence of 158Tb in the samples, which hinders precise activity determination. Mass separation emerges as a crucial method for obtaining pure 157Tb specimens. This work outlines the production of an isotopically-pure 157Tb sample through mass separation and ion implantation, using the RISIKO facility at the University of Mainz. The initial material was obtained from proton-irradiated Ta samples through radiochemical separation at the Paul Scherrer Institute. In total, a sample containing 8.7(9) · 1012 atoms of 157Tb was obtained. The efficiency of the mass separation and ion implantation was 13(2) %. The purified material served as the basis for new research endeavors at the Physikalisch Technische Bundesanstalt Braunschweig aiming at the determination of nuclear data for 157Tb with significantly improved precision.

Sm2Gd0.25Dy0.25Er0.25Yb0.25TaO7: A novel candidate thermal insulation oxide for high-temperature coatings

A novel high-entropy oxide, Sm2Gd0.25Dy0.25Er0.25Yb0.25TaO7, was synthesized via Sol-Gel and high-temperature calcining method. The powder and bulk specimen for Sm2Gd0.25Dy0.25Er0.25Yb0.25TaO7 were characterized, and its thermophysical performances were measured. The researching conclusions indicate that the synthesized nano-powder is very pure, and the block specimen has a sole pyrochlore structure, densified microstructure, and uniform distribution of elements. The low thermal conductivity is ascribed to phonon scattering stemmed from the ionic size and atomic mass disorders derived from multi-component addition. The high lattice-energy leads to a relatively low thermal expansion coefficient, which satisfies the demand of thermal barrier coating. The Sm2Gd0.25Dy0.25Er0.25Yb0.25TaO7 oxide also maintains outstanding phase steadiness up to 1200 °C.

In Situ-Grown Ultrathin Catalyst Layers for Improving both Proton Exchange Membrane Fuel Cell and Anion Exchange Membrane Fuel Cell Performances.

The mass transport and ion conductivity in the catalyst layer are important for fuel cell performances. Here, we report an in situ-grown ultrathin catalyst layer (UTCL) to reduce the oxygen mass transport and a surface ionomer-coated gas diffusion layer method to reduce the ion conducting resistance. A significantly reduced catalyst layer thickness (ca. 1 μm) is achieved, and coupled with the ionomer introduction method, the ultrathin catalyst layer is in good contact with the membrane, resulting in high ion conductivity and high Pt utilization. This ultrathin catalyst layer is suitable for both proton exchange membrane fuel cells and anion exchange membrane fuel cells, giving peak power densities of 2.24 and 1.11 W cm-2, respectively, which represent an increase of more than 30% compared with the membrane electrode assembly (MEA) fabricated by using traditional Pt/C power catalysts. Electrochemical impedance spectra and limiting current tests demonstrate the reduced charge transfer, mass transfer, and ohmic resistances in the ultrathin catalyst layer membrane electrode assembly, resulting in the promoted fuel cell performances.

Gas-Phase Unfolding Reveals Stability Shifts Associated with Substrate Binding in Modular Polyketide Synthases.

Native mass spectrometry (MS), ion mobility (IM), and collision-induced unfolding (CIU) have all been widely used to study the binding of small molecules to proteins and their complexes. Despite many successes in detecting subtle gas-phase stability differences in smaller systems dominated by single-domain subunits, studies targeting complexes comprised of large, multidomain subunits still face many challenges. For example, polyketide synthases (PKSs) are multiprotein enzymes that use their modular architecture to produce polyketide natural products and form the basis for nearly one-third of pharmaceuticals. Here, we describe the development of CIU methods capable of extracting information from these multiprotein complexes and demonstrate the current limits of quantitative CIU technology by probing the stabilities ∼280 kDa PKS dimer protein complexes. Our approach detects the evidence of the stability shifts associated with substrate binding that accounts for <0.1% of the mass for the intact assembly.

Magnetized multi-component plasmas sheath characteristics with three isothermal ion species

The dynamics of magnetized plasma sheath with three isothermal ions is studied numerically using the fluid model. The three ions ( Ar+,Kr+, and Xe+ ) are assumed to be singly charged and have the same temperature. In the beginning, the concentrations for Ar+ and Xe+ were taken in the same proportions, and then the Kr+ ion density is introduced slowly in the plasma. It is found that the presence of a third ion has changed the dynamics of ion densities inside the sheath and simultaneously their respective velocities. Ion density and electron density profiles were estimated inside the sheath region in the presence of a weak and strong magnetic field as well at different Kr+ ion concentrations. Further, the dependence of magnetic field obliqueness on the ion density profile and its velocities inside the sheath is also studied, and observed ion density bunching at different conditions. Based on the results, we have tried to introduce a concept of the derivation of system Bohm velocity by considering the ion mass as equivalent mass for the three interacting ion systems in the plasma. It is found that the system Bohm velocity with the equivalent mass effect is larger than their individual thermal velocities and close to Ar+ Bohm velocity, and higher than the system Bohm velocity with reference to the density ratio and their respective individual Bohm velocities in an isothermal multi-component plasma.

Energy-Resolving Time-of-Flight Mass Spectrometry for Bulk Plasma Analysis.

This work presents a newly designed energy-resolving time-of-flight mass spectrometer (E-TOFMS) for analysing the energy and mass of ions in bulk plasma. The system comprises an electrostatic sector analyser (ESA) for energy-to-charge (E/Q) ratio resolution and an orthogonal reflectron TOFMS for mass-to-charge (m/Q) ratio analysis. The design choices are explained, providing insight into electron and ion path simulations. The instrument was characterised using various ion generation sources, including an electron impact ion source, high power impulse magnetron sputtering, and microwave plasma electron cyclotron resonance sources. To validate its functionality, the energy-resolving data was compared with data obtained under the same conditions using a Langmuir probe and a retarding field energy analyser (RFEA). The benefits of the proposed E-TOFMS were demonstrated by sputtering highly alloyed steel with multiple isotope-rich elements, such as Mo or W. This technique offers an E/Q ratio resolution of up to 0.15 V for a range up to 125 V and a m/Q ratio resolution of at least 700 Th for a range up to 250 Th, with a temporal resolution of 10 μs.

Single ion mobility monitoring (SIM2) stitching method for high-throughput and high ion mobility resolution chiral analysis

Chiral analysis is of high interest in many fields such as chemistry, pharmaceuticals and metabolomics. Mass spectrometry and ion mobility spectrometry are useful analytical tools, although they cannot be used as stand-alone methods. Here, we propose an efficient strategy for the enantiomer characterization of amino acids (AAs) using non-covalent copper complexes. A single ion mobility monitoring (SIM2) method was applied on a TIMS-ToF mass spectrometer to maximize the detection and mobility separation of isomers. Almost all of the 19 pairs of proteinogenic AA enantiomers could be separated with at least one combination with the chiral references L-Phe and L-Pro. Furthermore, we extended the targeted SIM2 method by stitching several mobility ranges, in order to be able to analyze complex mixtures in a single acquisition while maintaining high mobility resolution. Most of the enantiomeric pairs of AAs separated with the SIM2 method were also detected with this approach. The SIM2 stitching method thus opens the way to a more comprehensive chiral analysis with TIMS-ToF instruments.Graphical