Cross-Beam energy transfer saturation: Ion heating and pump depletion

Cross-beam energy transfer (CBET) was measured in two regimes where the energy transfer saturation mechanism was determined by the plasma and laser beam conditions. Linear kinetic CBET theory agreed well with the measured energy transfer in all experiment configurations and at all probe beam intensities when accounting for pump depletion and the plasma conditions measured using Thomson-scattering. Simultaneous CBET and Thomson-scattering measurements enabled uncertainties in the plasma conditions to be isolated from CBET theory, which allowed the saturation mechanisms to be identified. In the perpendicular-beam configuration the saturation mode was through ion heating, which resulted from ion trapping in the driven waves and subsequent ion-ion collisional heating. In the co-propagating beam configuration there was minimal ion heating and the saturation mode was through pump depletion.

Li-Ion-Trapping-Induced Degradation Mechanism of Colored State in Tungsten Oxide Electrochromic Films

Aiming to investigate the degradation mechanism of their colored states, tungsten oxide films with different oxygen/tungsten ratio were prepared by direct current reactive magnetron sputtering through adjusting the oxygen partial pressure. After a long-term cycling test, the sample prepared under low oxygen partial pressure (LO#) showed an excellent cycle stability which its optical modulation amplitude remains stable at 23.6%, while the one prepared under high oxygen partial pressure (HO#) exhibited an obvious degradation process of the colored state, leading to the optical modulation amplitude decreased from 34.0% to 18.6% accompanied with a decay of ionic diffusion coefficient and electrode potential, but having an improved coloration efficiency. Combined with various structural characterizations, including SEM, LA-ICP-MS, Raman and XPS, we demonstrate such colored state degradation is attributed to the so-called shallow trap, which corresponds to the irreversible and non-coloring reaction with interstitial oxygen during the insertion of Li+ cations forming superoxides (e.g. LiO2). All these findings not only offer a new insight into the improvement of cyclic stability based on ion-exchange, but also provide a valued information to understanding the physicochemical mechanisms of degradation in electrochromic materials.

Ultrafast High-Voltage Kicker System for Ion-Clearing Gaps

Ionization scattering of electron beams with residual gas molecules causes ion trapping in electron rings, both in a collider and electron cooling system. These trapped ions may cause emittance growth, tune shift, halo formation, and coherent coupled bunch instabilities. In order to clear the ions and prevent them from accumulating turn after turn, the gaps in a temporal structure of the beam are typically used. Typically, the gap in the bunch train has a length of a few percent of the ring circumference. In those regions, the extraction electrodes with high pulsed voltages are introduced. In this paper, we present the design consideration and initial test results of the high-voltage pulsed kicker hardware that includes vacuum device and pulsed voltage driver, capable of achieving over 3 kV of deflecting voltage amplitude, rise and fall times of less than 10 ns, 100 ns flat-top duration at 1.4 MHz repetition rate.

Synthesis and Spectroscopy of Buckminsterfullerene Cation C60+ in a Cryogenic Ion Trapping Instrument

The assignment of several diffuse interstellar bands in the near-infrared to C60+ ions present at high abundance in space has renewed interest in the astrochemical importance of fullerenes and analogues. Many of the latter have not been produced in macroscopic quantities, and their spectroscopic properties are not available for comparison with astronomical observations. An apparatus has been constructed that combines laser vaporisation synthesis with spectroscopic characterisation at low temperature in a cryogenic trap. This instrument is used here to record the electronic absorptions of C60+ produced by laser vaporisation of graphite. These are detected by (helium tagged) messenger spectroscopy in a cryogenic trap. By comparison with spectra obtained using a sublimed sample of Buckminsterfullerene, the observed data show that this isomer is the dominant C60+ structure tagged with helium at m/z=724, indicating that the adopted approach can be used to access the spectra of other fullerenes and derivatives of astrochemical interest.

Enhanced Osteogenesis of Dental Pulp Stem Cells In Vitro Induced by Chitosan–PEG-Incorporated Calcium Phosphate Cement

The use of bone graft materials is required for the treatment of bone defects damaged beyond the critical defect; therefore, injectable calcium phosphate cement (CPC) is actively used after surgery. The application of various polymers to improve injectability, mechanical strength, and biological function of injection-type CPC is encouraged. We previously developed a chitosan–PEG conjugate (CS/PEG) by a sulfur (VI) fluoride exchange reaction, and the resulting chitosan derivative showed high solubility at a neutral pH. We have demonstrated the CPC incorporated with a poly (ethylene glycol) (PEG)-grafted chitosan (CS/PEG) and developed CS/PEG CPC. The characterization of CS/PEG CPC was conducted using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The initial properties of CS/PEG CPCs, such as the pH, porosity, mechanical strength, zeta potential, and in vitro biocompatibility using the WST-1 assay, were also investigated. Moreover, osteocompatibility of CS/PEG CPCs was carried out via Alizarin Red S staining, immunocytochemistry, and Western blot analysis. CS/PEG CPC has enhanced mechanical strength compared to CPC, and the cohesion test also demonstrated in vivo stability. Furthermore, we determined whether CS/PEG CPC is a suitable candidate for promoting the osteogenic ability of Dental Pulp Stem Cells (DPSC). The elution of CS/PEG CPC entraps more calcium ion than CPC, as confirmed through the zeta potential test. Accordingly, the ion trapping effect of CS/PEG is considered to have played a role in promoting osteogenic differentiation of DPSCs. The results strongly suggested that CS/PEG could be used as suitable additives for improving osteogenic induction of bone substitute materials.

Influence of Rhamnolipids and Ionic Cross-Linking Conditions on the Mechanical Properties of Alginate Hydrogels as a Model Bacterial Biofilm

The literature indicates the existence of a relationship between rhamnolipids and bacterial biofilm, as well as the ability of selected bacteria to produce rhamnolipids and alginate. However, the influence of biosurfactant molecules on the mechanical properties of biofilms are still not fully understood. The aim of this research is to determine the effect of rhamnolipids concentration, CaCl2 concentration, and ionic cross-linking time on the mechanical properties of alginate hydrogels using a Box–Behnken design. The mechanical properties of cross-linked alginate hydrogels were characterized using a universal testing machine. It was assumed that the addition of rhamnolipids mainly affects the compression load, and the value of this parameter is lower for hydrogels produced with biosurfactant concentration below CMC than for hydrogels obtained in pure water. In contrast, the addition of rhamnolipids in an amount exceeding CMC causes an increase in compression load. In bacterial biofilms, the presence of rhamnolipid molecules does not exceed the CMC value, which may confirm the influence of this biosurfactant on the formation of the biofilm structure. Moreover, rhamnolipids interact with the hydrophobic part of the alginate copolymer chains, and then the hydrophilic groups of adsorbed biosurfactant molecules create additional calcium ion trapping sites.