Abstract
Plasma diagnostics is a key tool to support the further development of plasma-induced chemical conversion of greenhouse gases (such as CO
2
) into high-value chemicals. For this reason, ...spectroscopic and electric measurements of low current (below 1.7 A), stationary arc plasmas in CO
2
at atmospheric pressure with addition of N
2
or H
2
O are reported. High-speed photography, imaging emission spectroscopy and time-resolved electrical measurements are used to obtain time-space resolved gas temperatures as well as the electric-field current characteristics of the discharge. It is found that the lowest average electric field in a CO
2
arc plasma at atmospheric pressure is ∼20 kV mm
−1
at a current between 0.8 and 1 A. If the current decreases below this level, the arc remains in vibrational–translational (VT) equilibrium by increasing the electric field. However, VT equilibrium conditions can be only maintained until a threshold minimum current of 0.33 ± 0.05 A, at which the arc transitions into a non-equilibrium condition with further increasing electric fields (reaching 68 ± 15 V mm
−1
at 0.03 A). The addition of N
2
or H
2
O did not influence the electrical characteristics of the CO
2
arc within to the tested mixtures. However, there is only a significant decrease in the electric field of the formed transition arcs and the threshold minimum current in the presence of N
2
. The spectra of the low-current CO
2
arc is found to be dominated by emission from the C
2
Swan band system and the O I 777 nm triplet peak. However, the CN band dominates the spectra even when small amounts (0.5 wt%) of N
2
is present in the plasma. The gas temperature at the axis of the CO
2
arc plasma decreased slightly with decreasing current, from an estimated 7000 K at 1 A down to 6300 K at 0.4 A. The thermal radius of the arc is estimated to be larger than 1.2 mm, more than two times larger than the optical radius obtained from the emitted radiation. The addition of N
2
and H
2
O (up to 7 and 9 wt% respectively) lead to only to a 500 K decrease in the axial arc temperature.
Prostate apoptosis response‐4 (Par‐4) tumor suppressor protein has gained attention as a potential therapeutic target owing to its unique ability to selectively induce apoptosis in cancer cells, ...sensitize them to chemotherapy and radiotherapy, and mitigate drug resistance. It has recently been reported that Par‐4 interacts synergistically with cisplatin, a widely used anticancer drug. However, the mechanistic details underlying this relationship remain elusive. In this investigation, we employed an array of biophysical techniques, including circular dichroism spectroscopy, dynamic light scattering, and UV–vis absorption spectroscopy, to characterize the interaction between the active caspase‐cleaved Par‐4 (cl‐Par‐4) fragment and cisplatin. Additionally, elemental analysis was conducted to quantitatively assess the binding of cisplatin to the protein, utilizing inductively coupled plasma‐optical emission spectroscopy and atomic absorption spectroscopy. Our findings provide evidence of direct interaction between cl‐Par‐4 and cisplatin, and reveal a binding stoichiometry of 1:1. This result provides insights that could be useful in enhancing the efficacy of cisplatin‐based and tumor suppressor‐based cancer therapies.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
In this work, the thermal effect induced by non-equilibrium plasma produced by nanosecond repetitively pulsed (NRP) glow discharges applied across a lean premixed methane–air flame is investigated. ...The flame is laminar, stationary, and axis-symmetric. The discharges are applied on the symmetry axis of the flame, crossing the fresh reactants, flame front, and burned gases. The obtained plasma-assisted flame is stable and reproducible, allowing phase-locked averaged diagnostics. The thermal effect is investigated by acquiring spatially and temporally resolved temperature measurements in the plasma discharges using optical emission spectroscopy (OES) of the second positive system of nitrogen. The results show that for an applied voltage of 10 kV, NRP glow discharges increased the gas temperature by up to 130 K within 10 ns. However, this heating was location-dependent, i.e., high near the anode tip and not detectable 0.5 mm above the anode. It was also shown that reducing the applied voltage down to 9 kV caused this ultra-fast heating to disappear. On the other hand, the reactants near the anode tip had a constant temperature of 480 K, between discharges, while the reactants were injected at 293 K. The reason for this slow heating could be due to (1) heating by the flame which is pulled down to the anode when NRP discharges are applied, (2) slow gas heating induced by relaxation of vibrational excited states of nitrogen, or (3) post-discharge oxidation chemistry. Based on temperature measurements performed on NRP corona discharges, heating by the flame could be ruled out. Zero-dimensional numerical simulations’ results suggest that post-discharge oxidation chemistry can heat the gas by 110–130 K, indicating that this is an important heating mechanism. Further investigation will be necessary to assess the significance of the vibrational–translational relaxation of nitrogen.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The optical emission of plasma on industrial steel samples induced by Laser Ablation-Spark Discharge-Optical Emission Spectroscopy (LA-SD-OES) and by Laser-Induced Breakdown Spectroscopy (LIBS) is ...investigated and correlated to the volume of ablated steel material. The 36 steel samples investigated have an iron content C(Fe) above 94 wt%. The excitation energy in LIBS (laser pulse of 55 mJ) and in LA-SD-OES (laser pulse of 5 mJ and spark discharge of 50 mJ) is the same. In LA-SD-OES, the optical emission of plasma and the size of ablation craters are very similar for all samples and a linear calibration curve for Mn is measured (R2 = 0.99). In LIBS, however, a pronounced dependence of the plasma emission and of the crater volume on the steel matrix is observed and calibration curves show a strong cross-sensitivity to other elements such as Si (matrix effect). The hardness, grain size, and phase of steel samples are analyzed to correlate the matrix effect in LIBS measurements to a physical property of the specimen. The different behavior for LA-SD-OES and LIBS is probably due to different processes of sampling and plasma excitation. From our results we conclude that LA-SD-OES enables for the element analysis of industrial steel largely independent of composition and structure of samples while in LIBS the matrix effect has to be taken into account.
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•Novel technique LA-SD-OES for the element analysis of steel.•Analyte emission intensities are independent of other elements in steel matrix.•Sampling in LA-SD-OES is independent of steel composition.•Linear calibration curves with high R2 for minor elements in steel.•LA-SD-OES overcomes strong matrix effect observed in LIBS of same samples.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
An argon actinometry approach which uses the 777 nm and 844 nm atomic oxygen lines along with the common N2/N2+ line ratio method is used to experimentally investigate the excitation mechanisms of ...the O(3p5P) state in medium pressure (0.75 Torr) N2-O2 plasmas. The method provides strong evidence that metastable excitation from the O(3s5S◦) state is an important excitation mechanism for O(3p5P) state for these conditions. The strong dependence of this additional mechanism on electron density along with the use of the N2/N2+ line ratio method allow for the simultaneous determination of effective electron temperature, dissociation fraction, metastable O(3s5S◦) density and electron density. Predicted electron temperatures, electron densities and dissociation fractions are consistent with those found for similar discharges in prior studies. Additionally, we investigate the efficacy of using the observed 616 nm atomic oxygen line from the O(4d5D◦) state for actinometry, which could open the door to a novel and comprehensive actinometry technique.
Aims
Low cardiac iron levels promote heart failure in experimental models. While cardiac iron concentration (CI) is decreased in patients with advanced heart failure with reduced ejection fraction ...(HFrEF), CI has never been measured in non‐advanced HFrEF. We measured CI in left ventricular (LV) endomyocardial biopsies (EMB) from patients with non‐advanced HFrEF and explored CI association with systemic iron status and disease severity.
Methods and results
We enrolled 80 consecutive patients with non‐ischaemic HFrEF with New York Heart Association class II or III symptoms and a median (interquartile range) LV ejection fraction of 25 (18–33)%. CI was 304 (262–373) μg/g dry tissue. CI was not related to immunohistological findings or the presence of cardiotropic viral genomes in EMBs and was not related to biomarkers of systemic iron status or anaemia. Patients with CI in the lowest quartile (CIQ1) had lower body mass indices and more often presented with heart failure histories longer than 6 months than patients in the upper three quartiles (CIQ2–4). CIQ1 patients had higher serum N‐terminal pro‐B‐type natriuretic peptide levels than CIQ2–4 patients 3566 (1513–6412) vs. 1542 (526–2811) ng/L; P = 0.005. CIQ1 patients also had greater LV end‐diastolic (P = 0.001) and end‐systolic diameter indices (P = 0.003) and higher LV end‐diastolic pressures (P = 0.046) than CIQ2–4 patients.
Conclusion
Low CI is associated with greater disease severity in patients with non‐advanced non‐ischaemic HFrEF. CI is unrelated to systemic iron homeostasis. The prognostic and therapeutic implications of CI measurements in EMBs should be further explored.
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
This work studies the characteristics of electrical discharge, optical emission spectroscopy and ozone production of an air-fed dielectric barrier discharge reactor. In particular, the reactor ...utilizes water as the high voltage electrode and the grounding electrode. Results show that when the applied peak-to-peak voltage is increased from 16.8 kV to 26.8 kV at 10 kHz, the specific input energy is increased from 19.0 J/L to 664.9 J/L. The maximum ozone generation efficiency reaches about 155 g/kWh with an ozone concentration of around 1549 ppm. The results also show that at a peak-to-peak voltage of 24.0 kV, the typical rotational temperature is 306 ± 5 K. In addition, during a 400 min stability test with ozone concentrations up to about 6000 ppm, the ozone generation efficiency is stabilized at around 106 g/kWh. The reactor can provide optimized control of the gas temperature and realizes energy-efficient ozone generation.
•Double water electrode is utilized in DBD ozone generation for the first time.•Energy efficiency is stabilized at 106 g/kWh with a concentration of 6000 ppm.•The rotational temperature is 305–308 K when Vpp is 20–28 kV.•Frequency positively affects the microdischarge number and emission intensify.•Ozone concentration is maximized at a frequency of 10 kHz at specific SIEs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Plasma-assisted ammonia (NH3) synthesis is receiving significant attention·NH3 is globally important to fertilizer production and as a fuel. However, plasma research is, intrinsically, significantly ...cross-disciplinary and encompasses chemistry, physics, materials science and electrical engineering. A consequence is that it is uncommon for plasma researchers to be fully aware of the entirety of plasma-related research beyond a particular discipline. Here for the first time we critically review this cross-disciplinary literature to address this problemusing plasma-enabled NH3synthesis as an eminent showcase for process chemistry.A justification is that an improved understanding will be helpful to deal with the complexity of plasma processes which typically involve a set of chemical reactions withan ensemble of manyshort-lived excited, or reactive, species that vary amongst different plasmas.In this way,mechanisms for plasma-driven NH3synthesis are deciphered which helps to improve plasma reaction engineering.Modern analytical techniques are critical in deciphering these fundamentals and in this review optical emission spectroscopy (OES) is featured.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Boron- and phosphorus-doped diamond layers were analysed by glow discharge optical emission spectroscopy. A methodology for quantitative depth profiling of layers was developed, based on multi-matrix ...calibration with a calibration model assuming matrix-independent emission yields. Factors affecting accuracy and sensitivity of analysis are discussed. Analysis of boron with the B I line at 208.959 nm yielded a satisfactory performance. Analysis of phosphorus with the P I line at 178.284 nm in an argon glow discharge is affected by an argon-related interference, which can be avoided by using a neon discharge. The use of which leads to an eightfold improvement in the phosphorus detection limit. A light interference effect affecting the analysis in transparent layers is described, indicating that layers are transparent far into the ultraviolet region.
Samples of B-doped diamond on silicon: the colours are due to thin-film interference, depending on layer thickness. The bright spots are erosion craters after GDOES analysis where the coating was sputtered away and the silicon substrate is exposed. Display omitted
•Quantitative analysis of B- and P-doped diamond layers by Glow discharge optical emission spectroscopy (GDOES) is described.•The methodology of the analyses is based on a multi-matrix sputter rate-corrected calibration.•The accuracy and the precision of the analyses is discussed, an excellent performance was achieved for boron.•There is a Ar line interference at the P line at 178.284 nm. It was avoided by using Ne as the discharge gas instead of Ar.•Periodic intensity variations occur in GDOES due to interference of light reflected from the coating and the substrate.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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