Single Ion Research Articles

Modulation of the Bonding between Copper and a Redox-Active Ligand by Hydrogen Bonds and Its Effect on Electronic Coupling and Spin States.

The exchange coupling of electron spins can strongly influence the properties of chemical species. The regulation of this type of electronic coupling has been explored within complexes that have multiple metal ions but to a lesser extent in complexes that pair a redox-active ligand with a single metal ion. To bridge this gap, we investigated the interplay among the structural and magnetic properties of mononuclear Cu complexes and exchange coupling between a Cu center and a redox-active ligand over three oxidation states. The computational analysis of the structural properties established a relationship between the complexes' magnetic properties and a bonding interaction involving a dx2-y2 orbital of the Cu ion and π orbital of the redox-active ligand that are close in energy. The additional bonding interaction affects the geometry around the Cu center and was found to be influenced by intramolecular H-bonds introduced by the external ligands. The ability to synthetically tune the d-π interactions using H-bonds illustrates a new type of control over the structural and magnetic properties of metal complexes.

Simultaneous Identification of Major Thyroid Hormones by a Nickel Immobilized Biological Nanopore.

Thyroid hormones (THs) are a variety of iodine-containing hormones that demonstrate critical physiological impacts on cellular activities. The assessment of thyroid function and the diagnosis of thyroid disorders require accurate measurement of TH levels. However, largely due to their structural similarities, the simultaneous discrimination of different THs is challenging. Nanopores, single-molecule sensors with a high resolution, are suitable for this task. In this paper, a hetero-octameric Mycobacterium smegmatis porin A (MspA) nanopore containing a single nickel ion immobilized to the pore constriction has enabled simultaneous identification of five representative THs including l-thyroxine (T4), 3,3',5-triiodo-l-thyronine (T3), 3,3',5'-triiodo-l-thyronine (rT3), 3,5-diiodo-l-thyronine (3,5-T2) and 3,3'-diiodo-l-thyronine (3,3'-T2). To automate event classification and avoid human bias, a machine learning algorithm was also developed, reporting an accuracy of 99.0%. This sensing strategy is also applied in the analysis of TH in a real human serum environment, suggesting its potential use in a clinical diagnosis.

Competitive Influence of Alkali Metals in the Ion Atmosphere on Nucleic Acid Duplex Stability.

The nonspecific atmosphere around nucleic acids, often termed the ion atmosphere, encompasses a collection of weak ion-nucleic acid interactions. Although nonspecific, the ion atmosphere has been shown to influence nucleic acid folding and structural stability. Studies investigating the composition of the ion atmosphere have shown competitive occupancy of the atmosphere between metal ions in the same solution. Many studies have investigated single ion effects on nucleic acid secondary structure stability; however, no comprehensive studies have investigated how the competitive occupancy of mixed ions in the ion atmosphere influences nucleic acid secondary structure stability. Here, six oligonucleotides were optically melted in buffers containing molar quantities, or mixtures, of either XCl (X = Li, K, Rb, or Cs) or NaCl. A correction factor was developed to better predict RNA duplex stability in solutions containing mixed XCl/NaCl. For solutions containing a 1:1 mixture of XCl/NaCl, one alkali metal chloride contributed more to duplex stability than the other. Overall, there was a 54% improvement in predictive capabilities with the correction factor compared with the standard 1.0 M NaCl nearest-neighbor models. This correction factor can be used in models to better predict RNA secondary structure in solutions containing mixed XCl/NaCl.

Highly Sensitive Acetylcholine Biosensing Via Chemical Amplification of Enzymatic Processes in Single Track-Etched Nanochannels

Neurotransmitters are endogenous chemical messengers that play crucial roles in the transmission, enhancement and conversion of specific signals between neurons and other cells and are considered biomarkers of neurodegenerative diseases.[1] Neurodegenerative diseases cause progressive loss of cognitive and/or motor function and, as life expectancy rises, they imply major challenges for societies with rapidly aging populations.[2] As a result, monitoring neurotransmitters is becoming increasingly relevant in clinical environments. Acetylcholine (Ach) is a neurotransmitter that plays a key role in the communication between neurons in the spinal cord and nerve skeletal junctions in vertebrates. [3] Since an abnormal concentration of Ach has proven to be related to neurodegenerative diseases, novel strategies for highly sensitive and specific Ach (bio)sensing are in great demand.In this work we present the construction of Ach enzymatic biosensors with remarkable sensitivity by acetylcholinesterase immobilization on polyamine-modified single nanochannels via electrostatic self-assembly. [4] To fabricate bullet-shaped single nanochannels in polyethylene terephthalate (PET), 12 µm thick PET foils are irradiated with a single swift heavy ion. The resulting ion track consists of highly localized damaged material along the ion trajectory and is selectively dissolved in a highly basic aqueous solution under asymmetric conditions to obtain a bullet-shaped channel. The controlled PET hydrolysis exposes carboxylic groups at the channel surface (negative charge at pH < 4), which allows the immobilization of further functional groups to design and construct the biosensor.Here, we will discuss in detail the sensor design, the applied functionalization strategy, and the performance of the sensor. In short, changes in the surface charge of the nanochannel lead to measurable changes in the transmembrane current in a steady-state configuration. We will show experimental results that evidence that the designed sensor successfully transduces the presence of acetylcholine into measurable ionic signals with a 16 nM low limit of detection.[1] World Health Organization, Neurological Disorders: Public Health Challenges, World Health Organization Press, Geneva, Switzerland,2007.[2] L. Gan, M. R. Cookson, L. Petrucelli and A. R. La Spada,Nat. Neurosci., 2018, 21, 1300–1309.[3] M. Hasanzadeh, N. Shadjou and M. de la Guardia, TrAC, Trends Anal. Chem., 2017, 86, 107–121.[4] Yamili Toum Terrones, Gregorio Laucirica, Vanina M. Cayón, Gonzalo E. Fenoy, M. Lorena Cortez, María Eugenia Toimil-Molares, Christina Trautmann, Waldemar A. Mamisollé and Omar Azzaroni, Chem. Commun., 2022, 58, 10166

Simultaneous quantification of seven glycols in antifreeze liquids using direct liquid injection gas chromatography coupled with mass spectrometry

Glycol‐based antifreeze liquids, commonly composed of ethylene glycol or propylene glycol, have important uses in automotive cooling, but they should be handled with care due to their toxicity. Ethylene glycol is highly toxic to humans and animals. A fast, accurate, precise, and robust method was developed for the simultaneous quantification of seven most important glycols and their isomers.MethodsGlycols were analyzed from diluted sample solution of coolants using gas chromatography coupled with mass spectrometry (GC–MC) in single ion monitoring mode.ResultsThe method was developed and validated for seven individual glycols (ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol). Limits of detection (1–2 μg/mL) and limits of quantification (10 μg/mL) obtained were appropriate. The present method was applied for the determination of glycols in 10 different antifreeze liquids commercially available on the Romanian market, proving to be reliable.ConclusionsA method that requires only a two‐step dilution of antifreeze samples combined with direct liquid injection GC–MS was validated for the simultaneous quantification of seven glycols (and their isomers) in 10 different types of antifreeze liquids. The results obtained in the validation procedure proved that the GC–MS method is sensitive and precise for the quantification of glycols.

Critical Minerals, Critical Capacity and Critical Evaluation

The battery industry is placed at a critical intersection between the two most extractive and unsustainable industries: mining and energy, where current ‘business as usual’ will lead to catastrophic outcomes for society and life on earth. This gives it a unique opportunity to be an extremely effective disruptive technology, helping end colonial systems which rely on extraction and transfer of wealth and resources from the global south to the global north, and create fair and just energy systems. In order to do this, the battery industry must make batteries from ethically sourced materials, with long lifetimes, that are recyclable. A key question remains on how exactly to evaluate the true sustainability of the components of the electric future, particularly lithium-ion batteries (LIB).This study presents electrochemical and materials characterisation data on several components of LIB, and a set of devised metrics for sustainability, to truly evaluate the potential of research cells in an industrial landscape.Lithium-ion batteries challenge the current energy system, rather than a single use system that must extract, ship and burn fuels constantly, LIB present a potential cyclical system where batteries are recharged, then repurposed before finally being recycled. Metals must still be mined, but this can be achieved sustainably in conjunction with the communities that reside in those areas, as part of an ESG initiative. In developing new technology and with the vast expansion of new industry particularly across Europe, there is enormous potential and responsibility to put in systems to facilitate a just energy transition. This applies all the way down at a materials development level. The systems to evaluate this however, are few and not widely discussed.In this work a case-study that aims to improve existing cell chemistry whilst focusing on its sustainability is presented. This includes the global context and in particular European criticality. The study builds on the premise behind the “Strategic materials Weighting And Value Evaluation" (SWAVE) framework to develop it further for new cell components and combinations.1 This study will focus primarily on the race to reduce cobalt and replace it with nickel and other transition metals. Reducing cobalt dependency is important to battery performance and ensuring that the energy transition is not reliant on a metal with restricted resourcing. However, whilst high nickel cathode content exhibits a higher specific capacity than cobalt-based material, it is less stable due to disordered Li+/Ni2+ cation mixing, lithium residuals upon the surface of the materials, and irreversible phase changes between the H2 and H3 phases at 4.2-4.3 V vs Li/Li+.2 Our results illustrate the difficulty in stabilizing the high nickel cathode materials with long lifetimes and discuss the possible successes in the results seen.Our study also explores the possibility of expanding beyond single ion systems, using alternative anode and electrolyte materials containing different ion transport. One example is Sodium, which offers a cheaper and more sustainable alternative to Lithium, and so replacing any sodium in existing cells would reduce the cost of the cell and reduce the reliance on the critical material lithium. With the creation of metrics of sustainability as within this study, any loss of capacity can be evaluated in context of the sustainability analysis to give the true ‘value’ of a potential cell in the industrial context. The feasibility of these full cell configurations are discussed, with formation, capacity and life-time testing. These results show some promising cell capacities with a variety of cell chemistries and components, whilst keeping in mind the overarching aim of a just energy transition to evaluate the developments made. References 1 R. Sommerville, P. Zhu, M. A. Rajaeifar, O. Heidrich, V. Goodship and E. Kendrick, Resour Conserv Recycl, 2021, 165, 105219.2 H. Ronduda, M. Zybert, A. Szczęsna-Chrzan, T. Trzeciak, A. Ostrowski, D. Szymański, W. Wieczorek, W. Raróg-Pilecka and M. Marcinek, Nanomaterials, 2020, 10, 2018.

Harmonization of Testing Procedures for All Solid State Batteries

All Solid State Batteries (ASSBs) with lithium-ion based conducting solid state electrolytes are considered the next generation high performance batteries. They enable high power densities due to their single ion conducting solid electrolyte, eliminating salt concentration gradients and related polarization losses in the cell, and ensuring an unrivalled level of safety due to their non-combustibility. Currently, a variety of ASSBs based on different solid state electrolytes such as polymers, thiophosphates, oxides and combinations thereof are being developed.One general problem with ASSBs is establishing and maintaining contact between the solid electrolyte and the active material phase during production and cycling, respectively. In conventional lithium-ion batteries (LiBs), this contact is ensured by the liquid state of the electrolyte, but in ASSBs, chemical expansion and contraction of the active material during lithiation and delithiation can detach this contact, resulting in decreased capacity due to the loss of active material. As a consequence, ASSBs are often operated under pressurized conditions, applying pressures significantly exceeding those in conventional LiBs. The same holds for the operating temperature window. Especially for polymer electrolyte-based ASSBs, they are often operated at higher temperatures to compensate for the low ionic conductivity of polymers at room temperature. With respect to cell testing, such operating requirements must be considered, and testing protocols are designed according to the individual requirements of the tested cell.This contribution aims to provide an overview of testing protocols for various types of ASSBs applied to different cells with polymer-, thiophosphate-, oxide-, and hybrid-electrolytes. These protocols will be compared with standardized testing routines for conventional LiBs. Based on this compilation, a harmonized testing procedure that covers the special requirements of the individual cell types and enables a fair comparison of different ASSBs is suggested. Additionally, examples of ASSB testing results will be discussed, taking into consideration the harmonization of different testing parameters.

(Poster Award Winner 2) Solvation Effects in Electrochemical Double Layers and Static Simulations

Batteries play a key role in future sustainable energy networks. Modelling these electro-chemical systems accurately provides a path to improved battery chemistries [1]. In recent years, research has identified highly concentrated electrolytes as promising constituents for battery cells with high energy density [2]. These are, however, complex systems, where the bulk electrolyte concentration and external electric potential significantly influences the electrochemical double layer (EDL) structure. It is challenging to model the behaviour of highly concentrated electrolytes near a charged surface.Here, we present a continuum transport theory for these materials, which incorporates solvation effects. The model is built up from the second law of thermodynamics by enforcing positive entropy production. By analysing contributions to entropy production, we can establish the free energy of the electrolyte system, which in turn constitutes the basic equations of the transport theory [3,4]. Our continuum model can describe both static and dynamic systems of highly concentrated electrolytes. To analyse the EDL, static simulations have proven effective due to their very low computation cost. Using this method, we are able to achieve concentration profiles at EDL length scales, when adding nonlocal contributions [4] even oscillatory behaviour can be recreated.Solvation is a key effect to consider when modelling reactions at the electrode surface or intercalation. The desolvation at the electrode surface constitutes an energy barrier, which must be overcome. Previous solvation models [5] use a static ion-solvent coordination number, therefore the stripping of the solvation shell in the double layer cannot be described. We address this concept by incorporating local solvation in our model, enabling a description of the electric forces desolvating ions in the EDL.Solvation is added to the free energy of the system by modifying the statistics which determine the entropic contribution. Additionally, we include a term to represent the ion-solvent interaction energy. Thus, two novel parameters are used to define the interaction – the maximum number of solvent molecules binding to a single ion, and the binding energy.We supplement our analytic discussion by numerical double layer simulations of an electrolyte consisting of an IL with a solvent, neutral or charged. Our results capture the relationship of ion-solvent binding energy and the desolvation potential. We can extract qualitative results down to a molecular scale from our model, allowing us to predict coarse grained behaviour of MD-simulations. By estimating the solvent coordination number at the electrode surface, it is possible to obtain a desolvation energy barrier.Figure: a ternary EDL for two different values of the binding energy, showing a nearly complete desolvation at the electrode for the smaller binding energyThis work was funded in the project POLiS by the Deutsche Forschungsgemeinschaft (DFG) under Germany´s Excellence Strategy – EXC 2154 – Project number 390874152.Literature: Armand, M.; Tarascon, J.-M. Nature 2008 451, 652.Giffin, G.A., Nat Commun 2022 13, 5250.Schammer, M. et al. J. Electrochem. Soc. 2021, 168, 026511.Schammer, M. et al. J. Phys. Chem. B2022, 126, 14, 2761–2776.Dreyer, W. et al. Electrochem. Comm. 2014, 43, 75-78. Figure 1

Multi-Functionalized High Ionic Conductive Soft Matter for Separator-Free All Solid-State Lithium-Ion Battery

Solid state battery (SSB) with its promising advantages such as extreme light weight, thin film manufacturing, and compact structure, which leads to a possibility of high energy density design (up to 400-500 Wh/kg). The most important key for the development of SSB is the solid electrolyte (SE). Nowadays, there are several SEs been studied to overcome many drawbacks that are being investigated. Those problems are low ionic conductivity at room temperature, low electrochemical stability, low interfacial compatibility, and low mechanical property, respectively. Although several SEs like sulfide, halide, oxide, and polymer-based materials are developed, but there are still big challenges for further commercialization.In this research, multi-functionalized high ionic soft matters have been synthesized successfully. These soft matters are siloxane polyelectrolytes that contains two functions of single ion transfer and lithium-ion compensation. With the single ion transfer design, the ionic conductivity of siloxane polyelectrolyte is achieved to 4*10-4 S/cm at room temperature and the electrochemical stability is illustrated to a window of 0-5.5V. This soft matter provides outstanding interfacial compatibility to solid-solid interface owing to its unique function of lithium-ion compensation by directly coverage on cathode active materials. According to the results, the impedance of SSB with siloxane polyelectrolytes is decreased by 50% as well as the initial capacity on NMC811 cathode is 213.3 mAh/g (CE: 91.4%). The cycle ability on this separator-free polymer based SSB shows almost no fading in 50 cycles (at 60oC) without any assistances, the SSB only has NMC811 cathode, SE, and lithium metal anode. Fig. 1 shows the SEM images of pristine and siloxane polyelectrolyte covered NMC811. According to the results, the NMC811 is homogeneously covered by thin film siloxane polyelectrolyte, which is used to transfer lithium ions.This research demonstrates a separator-free all SSB by multi-functionalized siloxane polyelectrolyte. High ionic conductivity, high interfacial compatibility, lithium-ion compensation, and high mechanical property are provided to a future high energy density battery. Figure 1

Single-Ion Counting with an Ultra-Thin-Membrane Silicon Carbide Sensor.

In recent times, ion implantation has received increasing interest for novel applications related to deterministic material doping on the nanoscale, primarily for the fabrication of solid-state quantum devices. For such applications, precise information concerning the number of implanted ions and their final position within the implanted sample is crucial. In this work, we present an innovative method for the detection of single ions of MeV energy by using a sub-micrometer ultra-thin silicon carbide sensor operated as an in-beam counter of transmitted ions. The SiC sensor signals, when compared to a Passivated Implanted Planar Silicon detector signal, exhibited a 96.5% ion-detection confidence, demonstrating that the membrane sensors can be utilized for high-fidelity ion counting. Furthermore, we assessed the angular straggling of transmitted ions due to the interaction with the SiC sensor, employing the scanning knife-edge method of a focused ion microbeam. The lateral dimension of the ion beam with and without the membrane sensor was compared to the SRIM calculations. The results were used to discuss the potential of such experimental geometry in deterministic ion-implantation schemes as well as other applications.

A modelling study to dissect the potential role of voltage-gated ion channels in activity-dependent conduction velocity changes as identified in small fiber neuropathy patients.

Patients with small fiber neuropathy (SFN) suffer from neuropathic pain, which is still a therapeutic problem. Changed activation patterns of mechano-insensitive peripheral nerve fibers (CMi) could cause neuropathic pain. However, there is sparse knowledge about mechanisms leading to CMi dysfunction since it is difficult to dissect specific molecular mechanisms in humans. We used an in-silico model to elucidate molecular causes of CMi dysfunction as observed in single nerve fiber recordings (microneurography) of SFN patients. We analyzed microneurography data from 97 CMi-fibers from healthy individuals and 34 of SFN patients to identify activity-dependent changes in conduction velocity. Using the NEURON environment, we adapted a biophysical realistic preexisting CMi-fiber model with ion channels described by Hodgkin-Huxley dynamics for identifying molecular mechanisms leading to those changes. Via a grid search optimization, we assessed the interplay between different ion channels, Na-K-pump, and resting membrane potential. Changing a single ion channel conductance, Na-K-pump or membrane potential individually is not sufficient to reproduce in-silico CMi-fiber dysfunction of unchanged activity-dependent conduction velocity slowing and quicker normalization of conduction velocity after stimulation as observed in microneurography. We identified the best combination of mechanisms: increased conductance of potassium delayed-rectifier and decreased conductance of Na-K-pump and depolarized membrane potential. When the membrane potential is unchanged, opposite changes in Na-K-pump and ion channels generate the same effect. Our study suggests that not one single mechanism accounts for pain-relevant changes in CMi-fibers, but a combination of mechanisms. A depolarized membrane potential, as previously observed in patients with neuropathic pain, leads to changes in the contribution of ion channels and the Na-K-pump. Thus, when searching for targets for the treatment of neuropathic pain, combinations of several molecules in interplay with the membrane potential should be regarded.

Slow magnetic relaxation of a {MnIIINaI}n zig-zag chain based single ion magnet

The synthesis using organic Schiff base ligands H2valen, and organic sulfonate ligands Na(4-HBS) in conjunction with Mn(Ac)3⋅2H2O, produces a one-dimensional coordination polymer with the formula {[Mn(valen)Na(4-HBS)2]⋅2CH3OH}n(1) [H2valen=6,6′-((1E,1′E)-(ethane-1,2-diylbis(azaneylylidene))bis(methaneylylidene))bis(2-methoxyphenol); Na(4-HBS)= Sodium 4-hydroxybenzenesulfonate]. Single crystal X-ray diffraction analysis reveals that complex 1 consist of neutral chains with one [Mn(valen)Na]2+ and two 4-HBS−moieties, in which the Mn(III) adopts an elongated octahedral geometry and Na(I) adopts a distorted pentagonal pyramid geometry, respectively. Magnetic investigations indicate the important magnetic anisotropy in the six-coordinated Mn(III) with the zero-field splitting parameter D = -3.2 cm−1. AC measurements suggest that complex 1 displays characteristics of slow magnetic relaxation under a 2000 Oe DC field, indicative of single ion magnet (SIM) behaviour. The effective energy barriers and the pre-exponential factor for complex 1 are determined to be 10.5 cm−1, and 1.36 × 10−7 s, respectively. This research reports not only a rare Mn(III) SIM molecular complex but also provide a potential approach to construct SIM chains.

The effect of aluminium concentration on the resistance of Si3N4 to ion track formation

The role of Al impurities on the structural response of polycrystalline silicon nitride to swift Xe and Bi ions at single ion track and overlapped ion track fluences is investigated. Si3N4 with Al impurity concentrations of 3 at.%, 1 at.% and 0.1. at.% were examined by means of high resolution scanning transmission electron microscopy. The threshold electronic energy loss (Set) required to form amorphous tracks was found to decrease with increasing Al fraction from above 33 keV/nm (0.1 at.% Al) to below 22 keV/nm for specimens containing about 3 at.% Al. All specimens were partially amorphized at overlapping ion fluence and the amorphous fraction monotonically increased with increasing Al content at the same ion fluence.

Nanoscale one-dimensional close packing of interfacial alkali ions driven by water-mediated attraction.

The permeability and selectivity of biological and artificial ion channels correlate with the specific hydration structure of single ions. However, fundamental understanding of the effect of ion-ion interaction remains elusive. Here, via non-contact atomic force microscopy measurements, we demonstrate that hydrated alkali metal cations (Na+ and K+) at charged surfaces could come into close contact with each other through partial dehydration and water rearrangement processes, forming one-dimensional chain structures. We prove that the interplay at the nanoscale between the water-ion and water-water interaction can lead to an effective ion-ion attraction overcoming the ionic Coulomb repulsion. The tendency for different ions to become closely packed follows the sequence K+ > Na+ > Li+, which is attributed to their different dehydration energies and charge densities. This work highlights the key role of water molecules in prompting close packing and concerted movement of ions at charged surfaces, which may provide new insights into the mechanism of ion transport under atomic confinement.

Sodium‐Ion‐Conducting Hydrogel Material: Synthesis, Characterization and Conductivity Studies

AbstractHerein we have reported single sodium ion conducting pseudo solid polymer electrolyte material, was synthesized successfully using sodium; 3,4,5,6‐tetrahydroxyoxane‐2‐carboxylate (ALG) and sodium salt of poly (acrylic Acid): SPA in the water as solvent via solution cast technique. This pseudo‐solid polymer material allows Na+ cation transport inside the matrix. The FTIR technique confirmed the appreciable interaction between the sodium alginate and sodium polyacrylate polymer. This amorphous polymer material has good flexibility, tensile strength, and good elasticity which provides a better electrode‐electrolyte interface. The material shows electrical conductivity in the range of 10−5 S/cm at room temperature and 10−4 S/cm at higher temperatures (&gt;40 °C). The material shows electrochemical stability of 2.26 V owing to a very good amount of current density with ≈97 % ionic transport number for the sodium ion. The material shows drift ionic velocity in the range of 10−4 m/s and ionic mobility in the order of 10−6 m2/Vs at room temperature. It shows the matrix ionic diffusivity constant in the order of 10−7 m2/s. It possesses low activation energy for ionic movement inside the matrix of 0.465 eV. The matrix shows the correlated type of hopping. An appreciable amount of capacitance is associated with the matrix with minute electrode contribution.

Simple Tool for Rapidly Assessing the Quality of Multiplexed Single Cell Proteomics Data.

Recent advances in the sensitivity and speed of mass spectrometers coupled with improved sample preparation methods have enabled the field of single cell proteomics to proliferate. While heavy development is occurring in the label free space, dramatic improvements in throughput are provided by multiplexing with tandem mass tags. Hundreds or thousands of single cells can be analyzed with this method, yielding large data sets which may contain poor data arising from loss of material during cell sorting or poor digestion, labeling, and lysis. To date, no tools have been described that can assess data quality prior to data processing. We present herein a lightweight python script and accompanying graphic user interface that can rapidly quantify reporter ion peaks within each MS/MS spectrum in a file. With simple summary reports, we can identify single cell samples that fail to pass a set quality threshold, thus reducing analysis time waste. In addition, this tool, Diagnostic Ion Data Analysis Reduction (DIDAR), will create reduced MGF files containing only spectra possessing a user-specified number of single cell reporter ions. By reducing the number of spectra that have excessive zero values, we can speed up sample processing with little loss in data completeness as these spectra are removed in later stages in data processing workflows. DIDAR and the DIDAR GUI are compatible with all modern operating systems and are available at: https://github.com/orsburn/DIDARSCPQC. All files described in this study are available at www.massive.ucsd.edu as accession MSV000088887.

Fabrication of biocompatible chitosan/graphene based nanocomposite for the competitive adsorption of heavy metal ions from wastewater in binary and ternary systems: Scale-up and upgradation studies

Coexistence of multiple metal ions in the wastewater alters the adsorption behavior compared to single metal ion system using the existing adsorbents which are chemically driven, requires harsh operating conditions and additional energy. The present study evaluates the performance of Chitosan/Graphene based nanocomposite for the competitive adsorption of heavy metals in single, binary and ternary systems. Maximum removal efficiency was 89.35 % (As), 90.41 % (Cu), 93.22 % (Ni), 96.47 % (Cd), 95.45 % (Pb) and 88.65 % (Cr) under optimum conditions (pH 4, Temperature = 25 °C, Equilibrium Time = 90 min, Adsorbent Dosage = 1.25 g and Initial Metal Ion Concentration = 150 mg/L) in a single system. A detailed investigation on the competitive adsorption of Cadmium, Copper, and Chromium ions was performed in binary. Maximum adsorption capacity was 1.55 mg/g and 1.48 mg/g (CuCd); 2.98 mg/g and 3.21 mg/g (CuCr) and 2.21 mg/g and 1.90 mg/g (CdCr system) at 4 mM concentration. The constructed mathematical models accurately forecast the adsorption behavior and shows a good match with the experimental data. Also, fixed-bed column studies were performed for the large-scale upgradation and optimum flow rate and bed height was 1 L/h and 15 cm at 25 °C. The study proposes the fabrication of natural-polymer based composite which can significantly reduce the dependency on synthetic and chemical-based adsorbents which poses severe negative impacts such as high-cost, poor selectivity and rapid saturation due to their low recyclability or sludge generation. Such application can effectively transform wastewater into contamination free water that could be valuable to society.

Highly conductive and nonflammable boron-based gel type single ion conducting electrolyte membranes toward high-safety and dendrite-free lithium metal batteries

Single-ion conducting polymer electrolytes (SIPEs), having a high Li-ion transference number (tLi+) close to unity, hold great promise for circumventing the lithium dendrite growth of lithium metal batteries (LMBs). However, SIPEs synthesized by a simple method that also simultaneously fulfill the requirements of high ionic conductivity, good thermal stability, and remarkable fire resistance are still quite rare. Herein, a novel single-ion conducting fibrous membrane (es-DDBSB-Li) based on borate anions of single-ion conductors (denoted as DDBSB-Li) and poly(vinylidene fluoride-hexafluoropropylene) P(VDF-HFP) as a binder was prepared via facile electrospinning technology. The introduction of borate anions promotes the homogeneous distribution of highly concentrated Li-ions and accelerates the ionic migration, leading to an enhanced ionic conductivity of 3.75 × 10−4 S cm−1 at 25 °C for DDBSB-Li saturated with organic solvents. Additionally, the thermally stable and nonflammable DDBSB-Li endows the resultant fibrous membranes to possess good high-temperature stability and fire-resistance properties. The Li||Li cell using this electrolyte displays a high tLi+ of 0.91 and effectively mitigates concentration polarization, thereby enabling a remarkably stable cyclic performance over 2000 h at 2.5 mA cm−2 at 25 °C. Also, this gel SIPE-based Li||LiFePO4 battery demonstrates superior rate performances up to 3C and delivers long-term cycling durability over 600 cycles under 1C at 25 °C. We believe this novel gel SIPE-based fibrous membrane has great potential for practical application in high-safety and dendrite-proof LMBs.

A sensitive high-resolution mass spectrometry method for quantifying intact M-protein light chains in patients with multiple myeloma

To determine the disease status and the response to treatment for patients with multiple myeloma, measuring serum M-protein levels is a widely used alternative to invasive punctures to count malignant plasma cells in the bone marrow. However, the quantification of this monoclonal antibody, which varies from patient to patient, poses significant analytical challenges. This paper describes a sensitive and specific mass spectrometry assay that addresses two objectives: to overcome the potential interference of biotherapeutics in the measurement of M-proteins, and to determine the depth of response to treatment by assessing minimal residual disease. After immunocapture of immunoglobulins and free light chains in serum, heavy and light chains were dissociated by chemical reduction and separated by liquid chromatography. M-proteins were analyzed by high-resolution mass spectrometry using a method combining a full MS scan for isotyping and identification and a targeted single ion monitoring scan for quantification. This method was able to discriminate M-protein from the therapeutic antibody in all patient samples analyzed and allowed quantification of M-protein with a LLOQ of 2.0 to 3.5 µg/ml in 5 out of 6 patients. This methodology appears to be promising for assessing minimal residual disease with sufficient sensitivity, specificity, and throughput.

Observing the primary steps of ion solvation in helium droplets.

Solvation is a ubiquitous phenomenon in the natural sciences. At the macroscopic level, it is well understood through thermodynamics and chemical reaction kinetics1,2. At the atomic level, the primary steps of solvation are the attraction and binding of individual molecules or atoms of a solvent to molecules or ions of a solute1. These steps have, however, never been observed in real time. Here we instantly create a single sodium ion at the surface of a liquid helium nanodroplet3,4, and measure the number of solvent atoms that successively attach to the ion as a function of time. We found that the binding dynamics of the first five helium atoms is well described by a Poissonian process with a binding rate of 2.0 atoms per picosecond. This rate is consistent with time-dependent density-functional-theory simulations of the solvation process. Furthermore, our measurements enable an estimate of the energy removed from the region around the sodium ion as a function of time, revealing that half of the total solvation energy is dissipated after four picoseconds. Our experimental method opens possibilities for benchmarking theoretical models of ion solvation and for time-resolved measurements of cation-molecule complex formation.