Ion Bursts Research Articles

Three‐Pronged Induction of Tumor Calcification Synergistic Calcium Immunotherapy Enables Diagnosis and Cure of Cancer

AbstractTumor calcification is considered to have the superiority of integrating tumor diagnosis and treatment, and it also has been found to be a predictor of favorable prognosis. However, selecting suitable nanocarriers and therapeutic drugs to maximize the tumor calcification efficiency are key factors for improving calcification‐medicated theranostics. This study performs a multi‐channel calcification nanoinitiator (CalNI, i.e., BP‐Cur‐Ca@PKLAK) by loading curcumin (Cur) and depositing Ca2+ on black phosphorus (BP) and combined carrying mitochondria‐targeting cytotoxic peptide KLAK to boost a triple‐induced tumor calcification. CalNI preferentially accumulates inside tumor mitochondria and induces multilevel calcification promotion by the three combined effects of (i) the degradation of BP into PO43− provides the phosphorus source required for calcification; (ii) burst of calcium ions can directly induce cellular calcium overload; (iii) Cur can inhibit calcium efflux thus further aggravate intracellular calcium stress. Moreover, KLAK exhibited enhanced mitochondrial synergistic toxic effects. Notably, the potential function of CalNI on the regulation of macrophage polarization could completely reverse the immunosuppressive microenvironment, and activate the initiation of T cell‐mediated immune response. Therefore, this three‐pronged CalNI showed a huge promise to be an alternative to conventional oncology therapy, which presents a more satisfactory therapeutic efficiency than any kind of single induction mode.

Enhanced Ion Acceleration Due To High‐Shear Tangential Discontinuities Upstream of Quasi‐Perpendicular Shocks

AbstractCollisionless shock waves are efficient ion accelerators. Previous numerical and observational studies have shown that quasi‐parallel (Q‖) shocks are more effective than quasi‐perpendicular (Q⊥) shocks at generating energetic ions under steady upstream conditions. Here, we use a local, 2D, hybrid particle‐in‐cell model to investigate how ion acceleration at super‐critical Q⊥ shocks is modulated when tangential discontinuities (TDs) with large magnetic shear are present in the upstream plasma. We show that such TDs can significantly increase the ion acceleration efficiency of 2D Q⊥ shocks, up to a level comparable to Q‖ shocks. Using data from the hybrid model and test particle simulations, we show that the enhanced energization is related to the magnetic field change associated with the discontinuity. When shock‐reflected ions cross the TD during their upstream gyromotion, the sharp field change causes the ions to propagate further upstream, and gain additional energy from the convection electric field associated with the upstream plasma flow. Our findings illustrate that the presence of upstream discontinuities can lead to bursts of energetic ions, even when they do not trigger the formation of foreshock transients. These results emphasize the importance of time‐variable upstream conditions when considering ion energization at shocks.

Jovian Periodicities (~10 h, ~40, 20, 15 min) at ACE, Upstream from the Earth’s Bow Shock, on 25–27 November 2003

It is known that Jovian radio and high energy electron emissions are observed near Earth. The question we address in this study is whether the quasi-periodic ~10 h and ~40/15–20 min (QP-10 h, QP-40/15–20 min) energetic particle and magnetic field periodicities observed by Ulysses during its distant encounter with Jupiter in 2003 were also detectable as far as the Earth’s orbit. Surprisingly, we found that at the end of the extreme 2003 Halloween events, during times of a highly disturbed Jovian magnetosphere, as inferred from strong bKOM radio emissions observed by Ulysses, and a magnetic connection of Earth with the Jovian magnetosphere, as suggested by simulation results of the interplanetary magnetic field (IMF), the ACE satellite observed, between at least 25–27 November 2013 at the Lagrangian Point L1 (LPL1), all the characteristic Jovian periodicities. In particular, by using high-time resolution data (1/5 min), we found, for the first time, quasi-permanent electron, and magnetic field QP-10/5 h, QP-40 min and QP-15/20 data variations at LPL1 for at least three days. These observations reasonably suggest that low energy (~50–~300 keV) Jovian electrons reached the Earth’s environment; the observations examined extend the lowest energy limit of the Jovian electron spectrum from 200 keV to ~50 keV. In addition, the ACE satellite observed an impressive series of QP-10/5 h energetic (≤0.05 MeV) ion bursts (EIBs) with strong cross-field intensity gradients at the onset/decay phase of the events and energy-dependent field aligned anisotropy suggesting ion streaming in the anti-sunward direction during their main phase. A comparison of simultaneously obtained measurements by ACE at the LPL1 and by Geotail upstream from the bow shock and in the magnetosphere suggests that the QP-10/5 h EIBs are inconsistent with the concept of a terrestrial origin. On the contrary, the observations indicate that the series of QP-10/5 h EIBs on 25–27 November 2003 was a spatial effect caused by the ~10/5 h quasi-periodic approach of a large-scale sheet to the Earth’s environment. The source of the ion population forming the QP-10/5 h sharp EIBs seems most probably Jovian ions accumulated in the interplanetary space, although a solar ion contribution is possible. Based on the above results, it is reasonable to suggest that the observed QP-10 h, QP-40 min and QP-15/20 periodicities are due to Jovian influence. Further research is needed to study the cause of the QP-10/5 h EIBs. This study presents new data which extend our view on the influence of the QP-10 h/QP-40/QP-15/20 min Jovian emissions from the outer to the inner heliosphere at 1 AU.

Impact of borosilicate bioactive glass scaffold processing and reactivity on in-vitro dissolution properties

In this study, bulk borosilicate glasses and 3D scaffolds (processed by the burn-off technique and by robocasting) were synthesized to investigate the impact of the manufacturing method, glass composition and preincubation time on in vitro dissolution and cell response. The studied compositions are based on commercial bioactive glass S53P4 (BonAlive) where 12.5% SiO2 has been replaced by B2O (labelled B12.5), and part of the CaO is replaced with MgO and SrO (labelled B12.5-Mg-Sr). First, the impact of the processing and glass composition, on the dissolution rate, was assessed. As expected, scaffolds were found to exhibit faster dissolution, due to the increased surface area, when compared to the bulk glass. Furthermore, the 3D printed scaffolds were found to dissolve faster than the burn-off scaffolds. Moreover, scaffolds made from B12.5-Mg-Sr glass composition exhibited slower ion release and precipitation of calcium phosphate (CaP) layer, when compared to B12.5, due to the stabilizing effect of Mg and Sr. Finally, dynamic condition produces lower ion releases that static condition and could be more optimal for in vitro cell growth. Secondly, in culture with murine MC3T3-E1 cells, it was shown that 3 days preincubation would be optimal to decrease the burst of ions that is known to lead to cell death. However, it was found that MC3T3-E1 survived and proliferated only in presence of B12.5-Mg-Sr scaffolds. Finally, it was shown that despite scaffolds having different porosities, they had no significant difference on human adipose-derived stem cells (hADSCs) survival. This manuscript brings new information on 1) the impact of material design (porosity) and composition on dissolution kinetic sand reactivity, 2) the impact of static vs dynamic testing on in-vitro dissolution and 3) the impact of materials’ pre-incubation on cell behavior.

Ion and electron acoustic bursts during anti-parallel magnetic reconnection driven by lasers

Ion and electron acoustic bursts during anti-parallel magnetic reconnection driven by lasers

Cellular irradiations with laser-driven carbon ions at ultra-high dose rates

Objective. Carbon is an ion species of significant radiobiological interest, particularly in view of its use in cancer radiotherapy, where its large Relative Biological Efficiency is often exploited to overcome radio resistance. A growing interest in highly pulsed carbon delivery has arisen in the context of the development of the FLASH radiotherapy approach, with recent studies carried out at dose rates of 40 Gy s−1. Laser acceleration methods, producing ultrashort ion bursts, can now enable the delivery of Gy-level doses of carbon ions at ultra-high dose rates (UHDRs), exceeding 109 Gy s−1. While studies at such extreme dose rate have been carried out so far using low LET particles such as electrons and protons, the radiobiology of high-LET, UHDR ions has not yet been explored. Here, we report the first application of laser-accelerated carbon ions generated by focussing 1020 W cm−2 intense lasers on 10–25 nm carbon targets, to irradiate radioresistant patient-derived Glioblastoma stem like cells (GSCs). Approach. We exposed GSCs to 1 Gy of 9.5 ± 0.5 MeV/n carbon ions delivered in a single ultra-short (∼400-picosecond) pulse, at a dose rate of 2 × 109 Gy s−1, generated using the ASTRA GEMINI laser of the Central Laser Facility at the Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK. We quantified carbon ion-induced DNA double strand break (DSB) damage using the 53BP1 foci formation assay and used 225 kVp x-rays as a reference radiation. Main Results. Laser-accelerated carbon ions induced complex DNA DSB damage, as seen through persistent 53BP1 foci (11.5 ± 0.4 foci/cell/Gy) at 24 h and significantly larger foci (1.69 ± 0.07 μm2) than x-rays induced ones (0.63 ± 0.02 μm2). The relative foci induction value for laser-driven carbon ions relative to conventional x-rays was 3.2 ± 0.3 at 24 h post-irradiation also confirming the complex nature of the induced damage. Significance. Our study demonstrates the feasibility of radiobiology investigations at unprecedented dose rates using laser-accelerated high-LET carbon ions in clinically relevant models.

Bursts of calcium ions prompt sensitive plants to fold up in defense

Bursts of calcium ions prompt sensitive plants to fold up in defense

Modulated Ultrasmall γ‐Fe2O3 Nanocrystal Assemblies for Switchable Magnetic Resonance Imaging and Photothermal‐Ferroptotic‐Chemical Synergistic Cancer Therapy

AbstractFerroptosis is recently discovered programmed cell death, induced by cellular ferrous ion bursts and subsequent Fenton reactions. The iron source in tumor cells is limited due to tightly controlled iron metabolism. Since hierarchical iron architecture is rarely considered in ferroptosis cancer treatment, multilayer Fe2O3 architectures (UF@PPDF NPs) are developed by modulating ultra‐small γ‐Fe2O3 nanocrystal assemblies, and further conjugating cancer cell targeting folic acid (FA), chemotherapeutic drug doxorubicin (Dox). Hierarchically assembled γ‐Fe2O3 nanocrystal facilitates switchable magnetic resonance imaging (MRI), much enhanced ferroptosis efficiency, and very high second near‐infrared (NIR‐II) photothermal conversion. For MRI, UF@PPDF nanoparticles (NPs) enables clearly visualized tissues in terms of size and compactness, with dynamic T2‐T1 imaging switching. UF@PPDF NPs exhibits highly efficient photothermal therapy (PTT) upon NIR‐II irradiation, together with controlled release of ferric ions and Dox, thus achieving PTT‐chemotherapy‐ferroptosis trifunctional synergistic cancer therapy for tumor ablation. RNA sequencing analyses of differentially expressed genes implies a multifaceted role for this therapy in cancer cell signaling. Cellular respiration and electron transport are significantly upregulated, while the epigenetic pathways, including chromatin modification and RNA transcription activity are severely downregulated, with an overall effect of cellular apoptosis. Thus, γ‐Fe2O3 architectures provide new possibility for highly efficient deep tumor treatment.

Time-synchronized laser-induced fluorescence in the near-field of a 600 Watt Hall thruster

We report on the results of an experimental campaign to measure time-varying velocity distributions in the near-field of a low power Hall thruster. We employ a sample-hold technique, enhanced by parallelizing the measurement hardware into several signal processing channels that vastly increases the data acquisition rate. The measurements are applied to study flow field dynamics in a commercial BHT-600 Hall thruster undergoing unforced breathing mode oscillations in the 44–49 kHz range. A very detailed experimental picture of the near-field emerges from these studies. The results indicate that velocity fluctuations lessen further downstream of the exit plane. Along the thruster axis where there is a general appearance of a central jet, there is evidence of a low velocity ion population in between the periodic bursts of high velocity ions, indicative of local ionization of neutrals outside of the thruster. One possible source of this residual ionization may be background chamber gas, which is not unexpected with the limited pumping capacity of ground test facilities.

Bunching and chopping for tandem accelerators. Part I: Bunching

A pulsed system capable of delivering up to a few microamps with a mass range 1–100 u, and with pulse width of bursts of ions approximately 1–2 ns is described. Critical design limitations are discussed to show the overall approach to meet a number of experimental requirements. The system consists of a SNICS negative ion source, a low energy buncher which uses the entire tandem electrostatic accelerator as a drift path to produce bunched ion bursts at the targets or linac entry, and high energy choppers. The buncher consists of a single acceleration gap with aligned removable grids. A detailed analysis is presented of the factors limiting the system performance, with the aim to lessen their effect on the ultimate minimum longitudinal phase space of the ion burst.

Biphasic ceramic bone graft with biphasic degradation rates.

In this study, the characteristics of a novel biphasic bone graft are reported. The bone graft is a physical mixture of calcium sulfate (CS) and hydroxyapatite (HA). This biphasic bone graft was prepared by sintering at 1100°C. Since the degradation rate of CS is much faster than that of HA, the CS/HA biphasic bone graft exhibits two degradation rates. The degradation rate is rapid (~10wt%/week) in the first stage and then slow (~1wt%/week) in the second stage. The biphasic bone graft has been implanted into the distal femur of rat. Most the bone graft was degraded 13weeks postoperatively. Instead, trabecular bone and vascular tissue are observed at the location of implant. The bone graft is unique for its burst of calcium ions at the start and its ability to remain stable throughout the degradation process. Its stable porous structure serves as an ideal scaffold for the formation of new bone as well as vascularization.

Ion bursts and multi-electron population in expanding laser-produced plasma

We present an experimental study of emission of relativistic electrons, fast ions and DD-fusion neutrons produced by interaction of sub-nanosecond laser radiation with solid targets performed at the PALS facility. Measurements of electron density close to the target surface using the femtosecond interferometry, energy distribution functions of hot electrons far from the target, and time-of-flight spectra of ions are performed. A multi population of electrons is formed as the laser interaction with plasma proceeds. Ions accelerated by hot electrons to MeV energy are emitted in bursts. The neutron yield from the deuterated target is compared to yields obtained from other experiments. Constraint of non-linear processes on the ion acceleration and resulting neutron yields is shown.

Characteristics of Escaping Magnetospheric Ions Associated With Magnetic Field Fluctuations

AbstractThe four Magnetospheric Multiscale (MMS) spacecraft observed energetic ( keV) ion bursts exhibiting an inverse dispersion in the magnetosheath on 28 December 2015. We consider the possibility that these ions originate from the magnetosphere. The ion composition ratios, flux levels, and the spectral slopes of the energetic ion energy spectra observed in the foreshock and in the magnetosheath resemble those in the outer magnetosphere but differ significantly from those seen further upstream from the bow shock at ACE. The particle gyrocenters lie earthward from the spacecraft, indicating that the maximum ion fluxes come from close to the magnetosphere. We provide important evidence that argues against an explanation of the particle source in terms of hot flow anomaly acceleration. A three‐dimensional global hybrid simulation shows that escaping magnetospheric ions can be scattered and transported across the magnetosheath. Ground magnetometer observations suggest that a solar wind pressure increase accelerates escaping magnetospheric ions via betatron acceleration, resulting in an inverse energy dispersion in the magnetosheath. However, there are no pressure changes detected on the MMS and ACE spacecraft and the ground magnetic field strength does not appear to be large enough to be consistent with the large magnetospheric compression needed to account for a betatron acceleration. Therefore, we suggest that the inverse energy dispersion event can be explained by a magnetic field rotation that connects MMS to the subsolar magnetosphere, enabling high‐energy particles from deep within the inner magnetosphere gain access to the magnetopause and magnetosheath.

Controlling energy distribution of fast ions and X-ray emission via target reliefs in ultrafast and relativistic laser plasma interaction

Secondary emission from laser produced plasma is governed by the electron distribution function. Therefore, its control is of utmost importance to steer the emission, e.g., of ultrashort bursts of high energy photons and ions for decisive application. Maximum gain is achieved if the laser light absorption by plasma is also maximized. In our theoretical analysis including comparison to recent experiments, we follow this route and study how the energy is transferred from a short laser pulse to the energy of fast ions and X-rays. We make use of ion and K-α emissions, which respond differently to branches of the electron distribution function when we optimize the laser light absorption via structuring of the target surface. Our investigation comprises laser intensities up to 5 × 1020 W/cm2 produced with femtosecond near infrared laser pulses and titanium foil targets of a few micrometer thicknesses. In particular, we reveal an energy relaxation process of hot electrons, which determines the observed laser intensity dependence of secondary emission and points to the benefit of target surface structuring in different optimization scenarios.

Measurement and analysis of fast transient instabilities

Abstract A novel beam diagnostics technique to detect fast beam transient instabilities and glitches has been developed at National Synchrotron Light Source II (NSLS-II). Vertical spikes of beam size and centroid have been observed occasionally and randomly during high current operations. These spikes are believed to be caused by ion instabilities associated with vacuum activity localized in the ring. With the functionality of gated beam position monitor (BPM), the newly developed technique utilizes turn-by-turn (TBT) data to detect beam centroid glitches. Whenever one turn trajectory deviates from a predefined window, a global control event is generated to trigger an online TBT data acquisition. The data acquisition is synchronized for all BPMs around the ring. In the meantime, the bunch-by-bunch (BxB) data, which is acquired from a single dedicated feedback BPM, has also been collected for analyzing possible coupled bunch instabilities (CBI). In addition to CBI caused mainly by ion bursts, other types of fast transient motions, such as, the top-off residual disturbance and fast orbit disturbance, have been captured with the new tool. The sources of the glitches can be approximately localized with the synchronized TBT data from multiple BPMs around the ring.

Impulsively Reflected Ions: A Plausible Mechanism for Ion Acoustic Wave Growth in Collisionless Shocks

AbstractWe present recent high time resolution observations from an oblique (43°) shock crossing from the Magnetospheric Multiscale mission. Short‐duration bursts between 10 and 100 ms of ion acoustic waves are observed in this event alongside a persistent reflected ion population. High time resolution (150 ms) particle measurements show strongly varying ion distributions between successive measurements, implying that they are bursty and impulsive by nature. Such signatures are consistent with ion bursts that are impulsively reflected at various points within the shock. We find that, after instability analysis using a Fried‐Conte dispersion solver, the insertion of dispersive ion bursts into an already stable ion distribution can lead to wave growth in the ion acoustic mode for short durations of time. We find that impulsively reflected ions are a plausible mechanism for ion acoustic wave growth in the terrestrial bow shock and, furthermore, suggest that wave growth can lead to a small but measurable momentum exchange between the solar wind ions and the reflected population.

Fast glitch detection of coupled bunch instabilities and orbit motions

During high current operation at NSLS-II storage ring, vertical beam size spikes have been noticed. The spikes are believed due to ion instability associates with vacuum activities localized in the ring. A new tool has been developed using gated BPM turn-by-turn (TBT) data to detect beam centroid glitches. When one turn orbit deviates outside the predefined window, a global event will be generated. This allows synchronized data acquisition of TBT beam positions around the ring. Bunch by bunch data is acquired at the same time to analyze the possible coupled bunch instabilities (CBI). Besides CBI mainly due to ion bursts, fast orbit glitches have been captured with the new tool. Sources of the glitches can be identified.

Observation of double pseudowaves in an ion–beam–plasma system**Project supported by the National Natural Science Foundation of China (Grant Nos. 11575183 and 11705201).

Pseudowaves, known as burst-ion signals, which are different from plasma normal modes, exist frequently in ion–wave excitation experiments when launching the waves by applying a pulsed voltage to a negatively biased grid. In previous experiments, only one kind of the pseudowave was observed. In this paper, we report the observation and identification of double pseudowaves in an ion–beam–plasma system. These pseudowaves originate from two ion groups: the burst of the beam ions and the burst of the background ions. It was observed that the burst of the background ions was in the case of high ion beam energy, while the burst of the beam ions was in the case of low ion beam energy. By observing the dependence of the signal velocities on the characteristics of the excitation voltage, these pseudowaves can be identified. It was also observed that the burst ion signal originating from the background ions can interact with slow beam mode and that originating from the beam ions can interact with fast beam mode.

Measurement of time dependence of energy and mass-charge composition of ion flux in short vacuum arc with nanosecond resolution

The temporal character of ion flux of a vacuum arc generation in nanosecond range was investigated by means of a multi-channel energy-mass analyser. The results obtained are the waveforms of arc current, discharge voltage and ion flux for few ion fractions with defined energy-to-charge ratios and several mass-to-charge ratios. The results show that the ion flux is constituted by 10–30 ns elementary bursts. These elementary bursts have durations that coincide in common to cathode spot life time estimations. The ion bursts combinations form both subsequent bursts groups and 100–150 ns super-bursts. The occurrence of the super-bursts usually precedes non-stabilities in the arc current and the attempts of the discharge to extinct. Amplitude Fourier spectrum dependence is close to Brownian random process dependence. The Fourier spectra of ion flux contain several local maxima corresponding to supposed cathode spot cycle period.

Plasma environment at the dawn flank of Jupiter's magnetosphere: Juno arrives at Jupiter

AbstractThis study examines the first observations from the Jovian Auroral Distributions Experiment (JADE) as the Juno spacecraft arrived at Jupiter. JADE observations show that Juno crossed the bow shock at 08:16 UT on 2016 day of year (DOY) 176 and magnetopause at 21:20 on DOY 177, with additional magnetopause encounters until 23:39 on DOY 181. JADE made the first detailed observations of the plasma environment just inside the dawn flank of the magnetopause. We find subcorotational ions and variable electron beaming, with multiple flux tubes of varying plasma properties. Ion composition shows a dearth of heavy ions; protons dominate the plasma, with only intermittent, low fluxes of O+/S++, along with traces of O++ and S+++. We also find very little or He+, which are expected for an ionospheric plasma source. A few heavy ion bursts occur when the radial field nears reversal, but many other such reversals are not accompanied by heavy ions.