Polar Ion Research Articles

Dicarboxylic acids analyzed by time-of-flight secondary ions mass spectrometry. Part II: Butanedioic acid

Time-of-flight secondary ion mass spectrometry was carried out to analyze a commercially available butanedioic acid (succinic acid) powder. Positive and negative polarity ion spectra were obtained using a 25 keV Bi3+ ion beam rastered over areas of 50 × 50 μm2. The main observed fragments were the protonated molecule [M+H]+ at 119 u and the deprotonated molecule [M-H]− at 117 u with their respective oligomers.

Dicarboxylic acids analyzed by time-of-flight secondary ions mass spectrometry. Part I: Propanedioic acid

Time-of-flight secondary ion mass spectrometry was carried out to analyze a commercially available propanedioic acid (malonic acid) powder. Positive and negative polarity ion spectra were obtained using a 25 keV Bi3+ ion beam rastered over areas of 50 × 50 μm2. The main observed fragments were the protonated molecule [M+H]+ at 105 Da and the deprotonated molecule [M-H]– at 103 Da with their respective oligomers.

Figuring the shape of the electron

Physics Although incomplete, the Standard Model (SM) of particle physics has been generally dependable in making correct experimental predictions. A curious case is the electric dipole moment of the electron (eEDM), which the SM predicts to be a lot smaller than do theories that aim to extend the SM. The eEDM can be measured using experiments with polar molecules and molecular ions, with the former boasting large fluxes and the latter long interrogation times. Cairncross et al. used molecular ions of HfF to find that the eEDM has a magnitude of less than 1.3 × 10−28 e cm, confirming an earlier result from neutral molecule measurements. Future experiments may yield even more precision, improving the ability to distinguish between the various extensions to the SM. Phys. Rev. Lett. 119 , 153001 (2017).

Direct Prediction of Calcite Surface Wettability with First-Principles Quantum Simulation

Prediction of intrinsic surface wettability from first-principles offers great opportunities in probing new physics of natural phenomena and enhancing energy production or transport efficiency. We propose a general quantum mechanical approach to predict the macroscopic wettability of any solid crystal surfaces for different liquids directly through atomic-level density functional simulation. As a benchmark, the wetting characteristics of calcite crystal (10.4) under different types of fluids (water, hexane, and mercury), including either contact angle or spreading coefficient, are predicted and further validated with experimental measurements. A unique feature of our approach lies in its capability of capturing the interactions among various polar fluid molecules and solid surface ions, particularly their charge density difference distributions. Moreover, this approach provides insightful and quantitative predictions of complicated surface wettability alteration problems and wetting behaviors of liquid/liquid/solid triphase systems.

Dicarboxylic acids analyzed by time-of-flight secondary ion mass spectrometry. Part 0: Ethanedioic acid

Time-of-flight secondary ion mass spectrometry was carried out to analyze a commercially available ethanedioic acid (oxalic acid) powder. Positive and negative polarity ion spectra were obtained using a 25 keV Bi3+ ion beam rastered over areas of 50 × 50 μm2. The main observed ions were the protonated molecule [M+H]+ at 91 Da and the deprotonated molecule [M-H]− at 89 Da with their respective oligomers.

Juno/JEDI observations of 0.01 to >10 MeV energetic ions in the Jovian auroral regions: Anticipating a source for polar X‐ray emission

AbstractAfter a successful orbit insertion, the Juno spacecraft completed its first 53.5 day orbit and entered a very low altitude perijove with the full scientific payload operational for the first time on 27 August 2016. The Jupiter Energetic particle Detector Instrument measured ions and electrons over the auroral regions and through closest approach, with ions measured from ~0.01 to >10 MeV, depending on species. This report focuses on the composition of the energetic ions observed during the first perijove of the Juno mission. Of particular interest are the ions that precipitate from the magnetosphere onto the polar atmosphere and ions that are accelerated locally by Jupiter's powerful auroral processes. We report preliminary findings on the spatial variations, species, including energy and pitch angle distributions throughout the prime science region during the first orbit of the Juno mission. The prime motivation for this work was to examine the heavy ions that are thought to be responsible for the observed polar X‐rays. Jupiter Energetic particle Detector Instrument (JEDI) did observe precipitating heavy ions with energies >10 MeV, but for this perijove the intensities were far below those needed to account for previously observed polar X‐ray emissions. During this survey we also found an unusual signal of ions between oxygen and sulfur. We include here a report on what appears to be a transitory observation of magnesium, or possibly sodium, at MeV energies through closest approach.

Enhanced dc conductivity and conductivity relaxation in PVDF/ionic liquid composites

To investigate the effects of 1-benzyl-3-methylimidazolium hexafluorophosphate on the crystal phase, morphology and dielectric relaxation behavior of poly(vinylidene fluoride) (PVDF), a series of PVDF/IL composites have been prepared using solution-cast method. The interaction between ILs and >CF2 groups of PVDF can facilitate the PVDF chains in amorphous area to form more polar phase for PVDF composites. In the frequency spectra of PVDF composites, MWS interfacial polarization, electrode polarization and dc conductivity resulted in high values of dielectric permittivity. The incorporation of ILs into the matrix can accelerate dc conductivity. The effect of IL on charge carrier movement mechanism was resulted from the increase of ion mobility induced by polar phase crystal and ion concentration.

Design of a TW-SLIM Module for Dual Polarity Confinement, Transport, and Reactions.

Here we describe instrumental approaches for performing dual polarity ion confinement, transport, ion mobility separations, and reactions in structures for lossless ion manipulations (SLIM). Previous means of ion confinement in SLIM, based upon rf-generated pseudopotentials and DC fields for lateral confinement, cannot trap ions of opposite polarity simultaneously. Here we explore alternative approaches to provide simultaneous lateral confinement of both ion polarities. Traveling wave ion mobility (IM) separations experienced in such SLIM cause ions of both polarities to migrate in the same directions and exhibit similar separations. The ion motion (and relative motion of the two polarities) under both surfing and IM separation conditions are discussed. In surfing conditions the two polarities are transported losslessly and non-reactively in their respective potential minima (higher absolute voltage regions confine negative polarities, and lower absolute potential regions are populated by positive polarities). In separation mode, where ions roll over an overtaking traveling wave, the two polarities can interact during the rollovers. Strategies to minimize overlap of the two ion populations to prevent reactive losses during separations are presented. A theoretical treatment of the time scales over which two populations (injected into a DC field-free region of the dual polarity SLIM device) interact is considered, and SLIM designs for allowing ion/ion interactions and other manipulations with dual polarities at 4Torr are presented. Graphical Abstract ᅟ.

Corrosion behavior of surface modifications on titanium dental implant. In situ bacteria monitoring by electrochemical techniques.

The effects of surface modifications and bacteria on the corrosion behavior of titanium have been studied. Five surface modifications were analyzed: two acid etchings (op V, op N), acid etching + anodic oxidation (op NT), sandblasting + acid etching (SLA), and machined surfaces (mach). The corrosion behavior of the surface modifications was evaluated by following the standard ANSI/AAMI/ISO 10993-15:2000. Cyclic potentiodynamic and potentiostatic anodic polarization tests and ion release by ICP-OES after immersion for 7 days in 0.9% NaCl were carried out. Microbiologically induced corrosion (MIC) of low and high roughness (mach, op V) was assessed in situ by electrochemical techniques. Streptococcus mutans bacteria were resuspended in PBS at a concentration of 3 × 108 bacteria mL-1 and maintained at 37°C. MIC was measured through the open circuit potential, Eoc , and electrochemical impedance spectroscopy from 2 to 28 days. Potentiodynamic curves showed the typical passive behavior for all the surface modifications. The titanium ion release after immersion was below 3 ppb. In situ bacteria monitoring showed the decrease in Eoc from -0.065 (SD 0.067) Vvs. Ag/AgCl in mach and -0.115 (SD 0.084) Vvs. Ag/AgCl in op V, to -0.333 (SD 0.147) Vvs. Ag/AgCl in mach and -0.263 (SD 0.005) Vvs. Ag/AgCl in op V, after 2 and 28 days, respectively. A reduction of the oxide film resistance, especially in op V (54 MΩcm2 and 6 MΩcm2 , after 2 and 28 days, respectively) could be seen. Streptococcus mutans negatively affected the corrosion resistance of titanium. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 997-1009, 2018.

Piezoresponse of ferroelectric films in ferroionic states: Time and voltage dynamics

The interplay between electrochemical surface charges and bulk ferroelectricity in thin films gives rise to a continuum of coupled ferro-ionic states. These states are exquisitely sensitive to chemical and electric conditions at the surfaces, applied voltage, and oxygen pressure. Using the analytical approach combining the Ginzburg-Landau-Devonshire description of the ferroelectricity with the Langmuir adsorption isotherm for the ions at the film surface, we have studied the temperature-, time- and field-dependent polarization changes and electromechanical response of the ferro-ionic states. The responses are found to be inseparable in thermodynamic equilibrium and at low frequencies of applied voltage. The states become separable in the high frequency dynamic mode due to the several orders of magnitude difference in the relaxation times of ferroelectric polarization and surface ion charge density. These studies provide an insight into the dynamic behavior of nanoscale ferroelectrics with an open surface exposed to different kinds of the electrochemically active gaseous surrounding.

Mineralogical and active mechanical excitation characteristics of filled fly ash cementitious materials

To reveal the influence of mechanical activation on the performance of fly ash, the microanalysis (the energy spectroscopy, XRD and SEM), the distribution size of particle of fly ash and cement paste intensity of various age for different grinding time were studied. The relationships of the activity and the composition of fly ash, microstructure and the distribution of particle size by mechanical activation of fly ash were obtained. The internal glass beads with activity were released by grinding fly ash for a certain time. The particle specific surface area was improved and the hydration reaction of the interface and the surface active center was increased by grinding. The granularity distributing of fly-ash trended towards optimization. The polar molecules or ions were easier to intrude into the internal cavity of the vitreous body. The active silica and alumina of fly ash were rapidly depolymerized. Each performance index of fly ash was increased before grinding for 20 min. Cement paste intensity of various age increased along with the grinding time, and the early strength increase range was big, but the later period intensity increase range hastened slightly. The internal part of vitreous of fly ash was destroyed if the fly ash continued to be ground and the activity of fly ash was reduced. It is suggested that Guozhuang's fly ash should be ground for 20 min.

A novel method for the quantitative determination of defects on graphene surfaces

In this work, a novel method for the quantitative determination of defects on graphene surfaces has been presented in order to provide accurate, reliable and quantitative information for the defects on graphene products. It was based on the selective adsorption of a specific polar organic ion (Sodium benzenesulfonate) on the edges and defects on graphene surfaces, and the atomic force microscopy (AFM) imaging of the adsorption. By means of an image processing software, the AFM images could be analyzed and the areas as well as area percentages of the defects on the graphene surfaces could be determined.

Potential energy curves determination and relative properties of NaSr+ molecular ion for the ground and several excited states

This work is focused to studying the electronic properties of NaSr+ cationic molecule. In this calculation, ab initio approach has been used including pseudopotential model, effective core potentials (ECP), and a full configuration interaction (FCI). Then, the first 50 electronic states are easily investigated over a large interval ranging from 4 to 300 a.u. of internuclear distance. From these investigated states, molecular spectroscopic parameters (T e , D e , R e and ω e ) and vibrational levels as well as their spacing have been derived. Moreover, dipolar properties of the different symmetries (131Σ, 113Σ, 91,3Π and 41,3Δ) for several states are determined for the first time as function as internuclear distance. Spectroscopic constants are then compared with the unique available theoretical study that is only limited to the study of the first 11 electronic states. Good agreement was obtained. According to our knowledge, no experimental study of NaSr+ system was done until now. The present theoretical study is realized aiming to be the first step toward the formation of ultracold polar molecular ion.

Trapped charge-driven degradation of perovskite solar cells.

Perovskite solar cells have shown unprecedent performance increase up to 22% efficiency. However, their photovoltaic performance has shown fast deterioration under light illumination in the presence of humid air even with encapulation. The stability of perovskite materials has been unsolved and its mechanism has been elusive. Here we uncover a mechanism for irreversible degradation of perovskite materials in which trapped charges, regardless of the polarity, play a decisive role. An experimental setup using different polarity ions revealed that the moisture-induced irreversible dissociation of perovskite materials is triggered by charges trapped along grain boundaries. We also identified the synergetic effect of oxygen on the process of moisture-induced degradation. The deprotonation of organic cations by trapped charge-induced local electric field would be attributed to the initiation of irreversible decomposition.

Effects of corona space charge polarity and liquid phase ion mobility on the shape and velocities of water jets in the spindle jet and precession modes of water electro-spray

The paper presents the experimental study of the effect of ions of different mobilities (H+, Cl−, Li+ and OH−) in electrosprayed water solutions under atmospheric pressure conditions in air and in SF6 background gas. Generally, at the atmospheric air conditions, the main difference between water electrospray (ES) in positive and in negative polarities is the shape and elongation direction of the water jets propagating from the charged nozzle. These phenomena can be associated with the movement of ions in water (i.e. the mobility of ions) or with the influence of the corona discharge and its ionic space charge. A comparison of HCl and LiOH water solutions with inversed mobility ratios of cations and anions showed that the mobility of ions inside the liquid is not an important parameter determining this difference between two ES polarities. The combined measurements in atmospheric air and SF6 gas clearly showed that the only important factor determining the different shapes and propagations of the water jets for both polarities is the corona discharge and its ionic space charge.

Multi-dimensional instability of dust-ion-acoustic solitary structure with opposite polarity ions and non-thermal electrons

An attempt has been made to study the multi-dimensional instability of dust-ion-acoustic (DIA) solitary waves (SWs) in magnetized multi-ion plasmas containing opposite polarity ions, opposite polarity dusts and non-thermal electrons. First of all, we have derived Zakharov-Kuznetsov (ZK) equation to study the DIA SWs in this case using reductive perturbation method as well as its solution. Small-k perturbation technique was employed to find out the instability criterion and growth rate of such a wave which can give a guideline in understanding the space and laboratory plasmas, situated in the D-region of the Earth’s ionosphere, mesosphere, and solar photosphere, as well as the microelectronics plasma processing reactors.

Dust-ion-acoustic solitary structure with opposite polarity ions and non-thermal electrons

The propagation of dust-ion-acoustic solitary waves in magnetized plasmas containing opposite polarity ions, opposite polarity dusts and non-thermal electrons has been studied. The fluid equations in the system are reduced to a Korteweg-de Vries equation in the limit of small amplitude perturbation. The effect of non-thermal electrons and the opposite polarity of ions and dusts in the solitary waves are presented graphically and numerically.

Review of Polarized Ion Sources

Recent progress in polarized ion sources development is reviewed. New techniques for production of polarized H[Formula: see text] ion (proton), D[Formula: see text] (D[Formula: see text]) and 3He[Formula: see text] ion beams will be discussed. A novel polarization technique was successfully implemented for the upgrade of the RHIC polarized H[Formula: see text] ion source to higher intensity and polarization. In this technique, a proton beam inside the high magnetic field solenoid is produced by ionization of the atomic hydrogen beam (from an external source) in the He-gas ionizer cell. Polarized electron capture from the optically-pumped Rb vapor further produces proton polarization (Optically Pumped Polarized Ion Source technique). The upgraded source reliably delivered beam for the 2013 polarized run in RHIC at [Formula: see text] = 510 GeV. This was a major factor contributing to RHIC polarization increase to over 60 % for colliding beams. Feasibility studies of a new polarization technique for polarized 3He[Formula: see text] source based on BNL Electron Beam Ion Source is also discussed.

Linear Viscoelasticity and Dielectric Spectroscopy of Ionomer/Plasticizer Mixtures: A Transition from Ionomer to Polyelectrolyte

For ionomers, unfavorable interaction between highly polar ion pairs and the low polarity polymer medium leads to ion aggregation. In contrast, for polyelectrolytes, the counterions prefer solvation in the polar medium to leave the chain charged and accordingly stretched due to the charge repulsion. In this study, linear viscoelastic and dielectric properties of mixtures of two ionomers with high dielectric constant low volatility plasticizers were examined. The ionomer chains having bulky side chains are not entangled. Upon increasing the plasticizer content, the terminal relaxation is significantly accelerated due to two effects: (1) a plasticizing effect lowering the Tg and (2) a higher dielectric constant that softens the ionic interactions, leading to ionic dissociation into isolated pairs that further boosts the static dielectric constant at low frequency/long time. A model incorporating these two mechanisms and utilizing a dielectric constant eC, after the nonionic segmental α relaxation as the rel...

Effects of Microwave Heating on Oil Palm Mesocarp

Sterilization is an essential pre-treatment step in crude oil extraction process as to retain the quality and minimize the enzymatic activity within the fruits. This pre-treatment process on fresh fruit bunches often involves a large amount of steam and pre-treatment processes. Hence, this produces a large amount of palm oil mill effluent (POME) and empty fruit bunch wastes. Moreover, additional drying processes are required to reduce the fruits’ moisture content for quality and storage purposes. Microwave energy is perceived as an alternative bringing improvement to the current process by introducing rapid heating as well as to improve process efficiency. The rapid heating process can effectively reduce power, energy and time required, yet capable of achieving the desired temperature through interaction between microwave, polar water molecules and charged ions in fresh fruit bunches. Other than that, microwave pre-treatment is a good alternative as it not only reduces the moisture content of fresh fruit bunches but also eliminates the production of POME, which is inevitable in the current process. Therefore, microwave technology is regarded as a clean process in the fresh fruit bunches pre-treatment. This paper reports the effects of microwave on the flesh of the oil palm fruits - mesocarp. Moisture content, dimensions and structure of the mesocarp are evaluated. The experimental results show that under the microwave treatment, the drying time required to reduce the moisture content of the mesocarp to 10 %, at power levels of 50 – 200 W, ranged from 2 – 35 min with the reduction of dimensions ranged from 3.6 – 6.2 %. Although varying the power level of microwave showed some degree of shrinkage, no significant changes were observed on the surface of the mesocarp. The experimental results demonstrated that microwave drying could provide a quicker drying process that resulted in least destruction occurred on the surface of the mesocarp.