Decrease In Electron Density Research Articles

Fluorinated triphenylphosphonium analogs improve cell selectivity and invivo detection of mito-metformin.

Triphenylphosphonium (TPP+) conjugated compounds selectively target cancercells by exploiting their hyperpolarized mitochondrial membrane potential. Todate, studies have focused on modifying either the linker or the cargo of TPP+-conjugated compounds. Here, we investigated the biological effects ofdirect modification to TPP+ to improve the efficacy and detection of mito-metformin (MMe), a TPP+-conjugated probe we have shown to have promising preclinical efficacy against solid cancer cells. We designed, synthesized, and tested trifluoromethyl and methoxy MMe analogs (pCF3-MMe, mCF3-MMe, and pMeO-MMe) against multiple distinct human cancer cells. pCF3-MMe showed enhanced selectivity toward cancer cells compared to MMe, while retaining thesame signaling mechanism. Importantly, pCF3-MMe allowed quantitative monitoring of cellular accumulation via 19F-NMR invitro and invivo. Furthermore, adding trifluoromethyl groups to TPP+ reduced toxicity invivo while retaining anti-tumor efficacy, opening an avenue to de-risk these next-generation TPP+-conjugated compounds.

Decrypting the Influence of Axial Coordination on the Electronic Microenvironment of Co-N 5 Site for Enhanced Electrocatalytic Reaction

Decrypting the Influence of Axial Coordination on the Electronic Microenvironment of Co-N ₅ Site for Enhanced Electrocatalytic Reaction

Response to “Comment on ‘The effects of radio-frequency bias on electron density in an inductively coupled plasma reactor’” [J. Appl. Phys. 132, 156101 (2022)

The rf-bias-induced decreases in plasma electron density observed by us [J. Appl. Phys. 102, 113302 (2007)] and others [Fox-Lyon et al., J. Vac. Sci. Technol. A 32, 030601 (2014)] are better explained by changes in gas composition, rather than neutral gas depletion.

Observation of the significant reductions of electron density and electron temperature in a cascaded arc high density argon plasma with ammonia seeding comparing with nitrogen seeding by laser Thomson scattering approach

• The influence of ammonia on the electron density and temperature in a high-density cascaded arc plasma has been studied by laser Thomson scattering. • The introduction of a small amount of ammonia gives rise to the dramatic decrease of electron density, electron temperature, local static plasma pressure and ion flux. • The results strongly suggest that the NH 3 seeding could be much efficiently to regulate the electron density and electron temperature compared with the N 2 seeding. In this work, the influences of ammonia (NH 3 ) seeding on the electron density ( n e ) and electron temperature ( T e ) in a high-density cascaded arc argon plasma have been investigated by laser Thomson scattering. As NH 3 seeding ratio increases from 0% to 2%, n e significantly decreases from 5×10 19 m -3 to 2×10 18 m -3 and T e changes from 0.41 eV to 0.34 eV. The investigations show that the reductions of electron density and electron temperature with ammonia seeding are much significant comparing with nitrogen seeding. The reduction of n e is attributed to the dissociated recombination reactions between electrons and molecular ions formed via the charge exchange reactions. The electron-impact vibrational excitation to molecules leads to the drop in T e . Both the drops in n e and T e cause the reduction of local static plasma pressure and ion flux. The findings strongly suggest that NH 3 gas could be a much effective impurity for achieving the detached-plasma.

Ozone at low concentration modulates microglial activity in vitro: A multimodal microscopy and biomolecular study.

Oxygen-ozone (O2 -O3 ) therapy is an adjuvant/complementary treatment based on the activation of antioxidant and cytoprotective pathways driven by the nuclear factor erythroid 2-related factor 2 (Nrf2). Many drugs, including dimethyl fumarate (DMF), that are used to reduce inflammation in oxidative-stress-related neurodegenerative diseases, act through the Nrf2-pathway. The scope of the present investigation was to get a deeper insight into the mechanisms responsible for the beneficial result of O2 -O3 treatment in some neurodegenerative diseases. To do this, we used an integrated approach of multimodal microscopy (bright-field and fluorescence microscopy, transmission and scanning electron microscopy) and biomolecular techniques to investigate the effects of the low O3 concentrations currently used in clinical practice in lipopolysaccharide (LPS)-activated microglial cells human microglial clone 3 (HMC3) and in DMF-treated LPS-activated (LPS + DMF) HMC3 cells. The results at light and electron microscopy showed that LPS-activation induced morphological modifications of HMC3 cells from elongated/branched to larger roundish shape, cytoplasmic accumulation of lipid droplets, decreased electron density of the cytoplasm and mitochondria, decreased amount of Nrf2 and increased migration rate, while biomolecular data demonstrated that Heme oxygenase 1 gene expression and the secretion of the pro-inflammatory cytokines, Interleukin-6, and tumor necrosis factor-α augmented. O3 treatment did not affect cell viability, proliferation, and morphological features of both LPS-activated and LPS + DMF cells, whereas the cell motility and the secretion of pro-inflammatory cytokines were significantly decreased. This evidence suggests that modulation of microglia activity may contribute to the beneficial effects of the O2 -O3 therapy in patients with neurodegenerative disorders characterized by chronic inflammation. HIGHLIGHTS: Low-dose ozone (O3 ) does not damage activated microglial cells in vitro Low-dose O3 decreases cell motility and pro-inflammatory cytokine secretion in activated microglial cells in vitro Low-dose O3 potentiates the effect of an anti-inflammatory drug on activated microglial cells.

Hydrogen plasma smelting reduction process monitoring with optical emission spectroscopy – Establishing the basis for the method

In the world of ever-increasing demand for carbon-free steel, hydrogen and recycling have an undeniable role in achieving net-zero carbon dioxide emissions for the steel industry. However, even though steel is one of the most recycled materials globally, the quantity of steel that can be made from recycled steel will probably not match the demand in the future. This in turn means that steel must be also produced from the conventional resource, the iron ore. Hydrogen has been proposed as an environmentally friendly alternative to carbon as a reducing agent. To tackle the problems related to the usage of hydrogen for this purpose, hydrogen plasma smelting reduction has been studied extensively in the last few years. This article aims to provide means for process control of the hydrogen plasma, which may show erratic and chaotic behavior during the smelting process. The method used is optical emission spectroscopy, with which the plasma can be characterized, its composition can be evaluated, and its temporal evolution can be assessed. This study sheds light on how the plasma behaves with different electrode gaps and flow gas compositions together with how the position of the arc with respect to the center of the crucible can be assessed. In Ar/H2 plasma, the plasma temperatures derived with OES varied between 4000 and 10000 K, and up to a 26% decrease in electron density was observed when increasing the electrode gap in 1 cm increments.

The repositioned drugs disulfiram/diethyldithiocarbamate combined to benznidazole: Searching for Chagas disease selective therapy, preventing toxicity and drug resistance.

Chagas disease (CD) affects at least 6 million people in 21 South American countries besides several thousand in other nations all over the world. It is estimated that at least 14,000 people die every year of CD. Since vaccines are not available, chemotherapy remains of pivotal relevance. About 30% of the treated patients cannot complete the therapy because of severe adverse reactions. Thus, the search for novel drugs is required. Here we tested the benznidazole (BZ) combination with the repositioned drug disulfiram (DSF) and its derivative diethyldithiocarbamate (DETC) upon Trypanosoma cruzi in vitro and in vivo. DETC-BZ combination was synergistic diminishing epimastigote proliferation and enhancing selective indexes up to over 10-fold. DETC was effective upon amastigotes of the BZ- partially resistant Y and the BZ-resistant Colombiana strains. The combination reduced proliferation even using low concentrations (e.g., 2.5 µM). Scanning electron microscopy revealed membrane discontinuities and cell body volume reduction. Transmission electron microscopy revealed remarkable enlargement of endoplasmic reticulum cisternae besides, dilated mitochondria with decreased electron density and disorganized kinetoplast DNA. At advanced stages, the cytoplasm vacuolation apparently impaired compartmentation. The fluorescent probe H2-DCFDA indicates the increased production of reactive oxygen species associated with enhanced lipid peroxidation in parasites incubated with DETC. The biochemical measurement indicates the downmodulation of thiol expression. DETC inhibited superoxide dismutase activity on parasites was more pronounced than in infected mice. In order to approach the DETC effects on intracellular infection, peritoneal macrophages were infected with Colombiana trypomastigotes. DETC addition diminished parasite numbers and the DETC-BZ combination was effective, despite the low concentrations used. In the murine infection, the combination significantly enhanced animal survival, decreasing parasitemia over BZ. Histopathology revealed that low doses of BZ-treated animals presented myocardial amastigote, not observed in combination-treated animals. The picrosirius collagen staining showed reduced myocardial fibrosis. Aminotransferase de aspartate, Aminotransferase de alanine, Creatine kinase, and urea plasma levels demonstrated that the combination was non-toxic. As DSF and DETC can reduce the toxicity of other drugs and resistance phenotypes, such a combination may be safe and effective.

Electron energy probability function measurement in a 2 MHz and 13.56 MHz dual-frequency capacitively coupled argon plasma

The effect of low-frequency power and high-frequency power on the electron energy probability function (EEPF) and the physical and electrical characteristics of plasma are experimentally investigated in a dual-frequency capacitively coupled plasma. RF powers of 2 MHz (low-frequency) and 13.56 MHz (high-frequency) are simultaneously applied to an electrode. EEPFs and DC self-bias voltages (V DC) are measured as one of the two RF powers is increased while the other is fixed. When the 2 MHz power increases at a fixed 13.56 MHz power, the electron density decreases, and the electron temperature increases with the decrease in the population of low-energy (below 5 V) electrons in the EEPF. Note that the increase in the low-frequency power is accompanied by a large decrease in V DC, which is related to the ion energy. On the other hand, when 13.56 MHz power increases at a fixed 2 MHz power, the electron density and the electron temperature significantly increase with the increase in the population of high-energy (above 5 V) electrons in the EEPF, while V DC decreases slightly. Experimental results show that the increase in the low-frequency power enhances the ion energy, and the increase in the high-frequency power enhances electron heating and ionization efficiency.

A Study on Structure, Stability, Cooperativity and Hydrogen Bond in the Complexes of nHCHO and nH2O (n=1-3) by Quantum Chemical Method

Eight stable structures of nHCHO∙∙∙nH2O (n=1-3) were observed on potential surface energy at the MP2/aug-cc-pVDZ level of theory. All complexes were mainly stabilized by O-H∙∙∙O hydrogen bond and an additional contribution of Csp2-H∙∙∙O one. The larger positive cooperativity when adding H2O as compared to HCHO molecule is the most important factor in complex stabilization. The obtained results show that the O-H∙∙∙O is red-shifting hydrogen bond while Csp2-H∙∙∙O belongs to blue-shifting hydrogen bond. It is remarkable that an addition of H2O/HCHO into the binary system leads a Csp2-H bond contraction and an increase of its stretching frequency in Csp2-H∙∙∙O hydrogen bond, in which the larger marnitude of its blue-shifting enhancement is found as adding H2O molecule. This result is mainly governed by a decrease of electron density at σ*(Csp2-H) orbital and an increase in the s-character percentage of the Csp2 (Csp2-H).

Temporal Evolutions of Self-Organized Patterns Formed on the Water-Anode Surface of an Atmospheric Pressure Glow Discharge

Atmospheric pressure glow discharge above water anode has attracted much attention due to its extensive potential applications, where self-organized patterns can be formed. Usually, they are time-invariant under constant conditions. In this article, some peculiar time-dependent patterns are formed, among which concentric ring patterns like single, triple, quadruple, and quintuple rings are observed in water-anode discharge system for the first time. Accompanying the increasing complexity of patterns, results indicate that water conductivity evolves with time. Optical emission spectroscopy reveals that before reaching constant values, electron density decreases, while electron and gas temperatures increase as time elapses. Interestingly, the temporal variations of electric conductivity and plasma parameters are correlated with the evolution of patterns. Based on the phenomena mentioned above, the pattern evolution is qualitatively explained based on the Turing mechanism at last. We think these results will shed light on formation mechanism of patterns in atmospheric pressure glow discharge with water anode.

Experimental study of transition from electron beam to rf-power-controlled plasma in DFCCP in argon with additional ionization by an electron beam

Radio-frequency (rf) plasma with additional ionization by an electron beam (EB) is considered as a possible method for the independent control of plasma density, mean electron energy and mean ion energy. In this study, spatial transition from EB to rf-power-controlled dual-frequency capacitively coupled plasma (DFCCP) was studied using the following movable diagnostics: Langmuir and hairpin probes, a retarding field energy analyzer and optical emission spectroscopy. The beam (1.1–1.4 keV) is generated by a runaway EB module placed near the plasma chamber wall, while the plasma transition is caused by EB degradation with the distance from the EB module. The study was conducted in Ar at 200 and 400 mTorr gas pressures in 81 and 12 MHz DFCCP. When the EB is on, a significant decrease in the mean electron energy is observed, from 6 eV in the rf plasma down to 0.2–0.8 eV in the EB plasma. The EB also changes the shape of the electron energy probability function, from Druyvesteyn-like in rf plasma to Maxwellian-like. When both EB and rf power are applied, the mean electron energy increase and the electron density decrease, with the distance from the EB module, are observed due to the beam degradation. The ion energy distribution at the bottom electrode in rf plasma peaks at 25–30 eV and shifts down to a few eV in EB plasma. As in conventional DFCCP, the ion energy distribution can be fine-tuned by the application of a low-frequency rf bias. However, the use of an EB allows us to reduce the range of ion energies down to a few eV, which cannot be achieved in conventional rf discharges.

Investigation of the negative ionospheric response of the 8 September 2017 geomagnetic storm over the European sector

In this study, we investigate the negative ionospheric response over the European sector during two storms that took place on 8 September 2017, primarily, by exploiting observations over ten European locations. The spatial and temporal variations of TEC, foF2 and hmF2 ionospheric characteristics are examined with the aim to explain the physical mechanisms underlying the strong negative ionospheric response. We detected very sharp electron density (in terms of foF2 and TEC) decrease during the main phases of the two storms and we attributed this phenomenon to the large displacement of the Midlatitude Ionospheric Trough (MIT). Our study also revealed that the two storms show different features caused by different processes. In addition, Large Scale Traveling Ionospheric Disturbances (LSTIDs) were observed during both storms, followed by enhanced Spread F conditions over Digisonde stations. The regional dependence of ionospheric storm effects was demonstrated, as the behavior of ionospheric effects over the northern part of Europe differed from that over the southern part.

The application of a helicon plasma source in reactive sputter deposition of tungsten nitride thin films

A reactive helicon wave plasma (HWP) sputtering method is used for the deposition of tungsten nitride (WN x ) thin films. N2 is introduced downstream in the diffusion chamber. The impacts of N2 on the Ar-HWP parameters, such as ion energy distribution functions (IEDFs), electron energy probability functions (EEPFs), electron temperature (T e) and density (n e), are investigated. With the addition of N2, a decrease in electron density is observed due to the dissociative recombination of electrons with The similar IEDF curves of Ar+ and N2 + indicate that the majority of stems from the charge transfer in the collision between Ar+ and N2. Moreover, due to the collisions between electrons and N2 ions, EEPFs show a relatively lower T e with a depletion in the high-energy tail. With increasing negative bias from 50 to 200 V, a phase transition from hexagonal WN to fcc-WN0.5 is observed, together with an increase in the deposition rate and roughness.

Characterization of the laser-induced breakdown spectroscopy near the gas-liquid two-phase interface.

The characterization of laser-induced breakdown spectroscopy (LIBS) near the gas-liquid two-phase interface was investigated with the laser acting on the sample along the horizontal direction. Simulation of the laser beam focusing process and observation of laser beam spot images show that difference in focusing positions in the air and the solution results from refraction of the laser beam entering the solution from the air and the change of propagation direction on the container lateral. The peak power and mean irradiance of the focused laser beam spot increase with the distance away from the interface, which is attributed to the fact that the loss of laser energy due to the refraction and reflection of light at the interface decreases with the focusing position moving away from the interface. This variation trend of laser irradiance allows for the growth of the spectral line intensity and lifetime with increasing the distance from the interface. The plasma electron density and temperature decrease with the delay time but increase with the distance away from the interface at the same delay time. Our findings help us to gain more insight into the characteristics and evolution mechanisms of LIBS produced near the gas-liquid two-phase interface, which provides theoretical guidance for the correction of LIBS spectra especially in water pollution monitoring.

Stable Metal–Halide Perovskite Colloids in Protic Ionic Liquid

Stable Metal–Halide Perovskite Colloids in Protic Ionic Liquid

The power loss requirement in the non-thermal ³He-³He fusion plasma

The control of power loss is the most important issue in the plasma and it should be minimised by suitable selection of design parameters. This research is done with the aim of determining power loss and the parameters affecting the ³He-³He plasma with isotropic non-Maxwellian electron velocity distribution function (EVDF). In order to investigate the power loss requirement, bi-Maxwellian EVDF is considered. The results show that the rate of entropy production decreases as the electron density decreases and collision time increases. The ratio of the minimum power loss to the fusion power decreases as the electron temperature, and electron and helium-3 densities decrease, and the ion temperature increases. It is favourable to decrease the electron temperature lower than the thermal limit. Moreover, decreasing the electron temperature increases the fusion power.

Studying the Effect of Delay Time on Intensity of Laser Induced Breakdown Spectroscopy Technique Using Mas Cement Sample

Cement is a soft bond material that hardens and acquires its mechanical properties in the presence of water; it is an industrial product that has many uses, including its use in construction, roads, bridges, and others. It is important in our life to know its components. In this study, a laser-induced breakdown spectrometer was used to detect the elements present in a sample of Sudanese mas cement. In this technique, a high-energy laser is applied to the surface of the sample, ionizing the atoms of the material and then evaporating it, and then producing hot plasma on the surface of the sample, and this plasma is analyzed with a spectrometer, and thus the components of the sample can be known. The laser source used in this study is (Nd: YAG). Delay times are one of the factors affecting the intensity of the libs signal, To determine the relationship between laser delay times and LIBS signal intensity, a mas cement sample was irradiated with 32mj laser pulse energy and (200, 300, 400, 500, 600, 700, 800, 1000, 2000) nanoseconds delay times. We observed a decrease in the LIBS signal with increasing laser delay times. For quantitative analysis, the plasma temperature and electron density at (300, 500 and 700) laser delay times at 32mj laser pulse energy were calculated using standard equations and well-resolved spectral lines for Ca in the region of (422.67, 430.25 and 430.774) nm. It has been observed that when the delay time increases, the plasma temperature decreases and the electron density decrease. It was found that the density of electrons is directly proportional to the temperature of the plasma.

Effects from the June 10, 2021 solar eclipse in the ionosphere over Kharkiv: results from ionosonde measurements

Background. Ionospheric effects from solar eclipses (SEs) have been studied for over a century. The studies intensified in the 1960–1970, when rockets, satellites, ionosonde networks, and incoherent scatter radars became actively involved in the investigations. The following basic features of SEs displayed in the ionosphere have been established: a decrease in the electron density and the electron, ion, and neutral temperatures, changes in the dynamics of the ionosphere, and the generation of acoustic and atmospheric gravity waves. The recurring regular features are observed together with the features pertaining to each individual SE. Therefore, the study of the effects of each new solar eclipse is an urgent task. The purpose of this paper is to present the results of analysis of the ionogram measurements acquired by the digisonde located at the Radiophysical Observatory, V. N. Karazin Kharkiv National University. Techniques and Methodology. The observations of the state of the ionosphere were made using the digisonde specifically developed by the V. N. Karazin Kharkiv National University and located at the V. N. Karazin Kharkiv National University Radiophysical Observatory (49°38' N, 36°20' E). The data processing included the following. First, the time series of critical F2-layer frequencies, foF2, of the minimum frequency, fmin, observed on an ionogram, and of the virtual height were plotted. Second, the trends and the differences between the initial series and the trends were calculated. Third, given the foF2(t) values, the electron densities N(t) and their increments ΔN(t) were calculated, and fourth, the systems spectral analysis of ΔN(t) dependences was conducted to determine the spectral content. Results. A maximum decrease of 3.7–3.8% in the F2 peak electron density has been detected. This value agrees very well with the calculated value of 3.5–3.8%. The time delay between the minimum in the electron density observed and the maximum value of the phase of the solar eclipse was determined to be 12.5 min, which is in good agreement with the calculated value of 12.8 min. The time delay suggests that the linear loss coefficient was 1.3´10–3 s–1 and the production rate was (3.8–3.9)×108 m–3∙s–1. The SE was associated with the generation of quasi-periodic oscillations in the electron density and the F2 layer virtual height, within the period range of 10–15 min, and with amplitudes of 1.7–4% and 9.1–11.4%, respectively. The fluctuations in the minimum frequency observed on the ionograms showed a factor of 3–4 times decrease in the course of the SE. In addition, a decrease in the averaged values was observed to occur from 3 to 2.85 MHz (by 5%), which suggested that the radio wave attenuation by absorption decreased due to a decrease in the lower-ionosphere electron density below 100 km altitude. This decrease was estimated to be about 2%, while the decrease determined from the observations gave 2.2%. Conclusions. The partial solar eclipse with a very small value of the maximum magnitude (0.112) and obscuration of 4.4% acted to produce a few effects observed in the ionosphere with the ionosonde.

Influence of the concentration of chenodeoxycholic acid on the performance of the N719 dye

The influence of the Chenodeoxycholic acid (CDCA) at different concentrations on the spectroscopic and photovoltaic performances of the N719 dye was determined. Absorption analyses revealed the excellent capacity of the CDCA in stabilizing the N719 dye. The N719 dye exhibited hydroxyl and carboxylic functional groups that were accountable for the strong interactions and fast transport of electrons to the TiO2 surface. The photoluminescence emission spectroscopy of the CDCA-incorporated dye exhibited the feasibility of a large photocurrent generation. The interaction mechanism of CDCA within the N719 dye influenced the efficiency of the fabricated cell because the high photoconversion efficiency of 4.07% was recorded for 0 mM CDCA. This finding was because CDCA decreased the electrolyte contact with the N719 dye, resulting in charge accumulation in the electrolyte and decreased electron density in the N719 dye. Present findings are beneficial for the development of efficient dye-based DSSCs.

Influence of different O2/H2O ratios on He atmospheric pressure plasma jet impinging on a dielectric surface

A two-dimensional (2D) axisymmetric fluid model is built to investigate the effect of different O2 and H2O admixture on the plasma dynamics and the distribution of reactive species in He atmospheric pressure plasma jet (APPJ). The increase of O2:H2O ratio slows down both the intensity and the propagation speed of the ionization wave. Due to the decrease of both H2O ionization rate and H2O Penning ionization as well as the stronger electronegativity of O2, the increase of O2:H2O ratio results in a significant reduction of electron density in the APPJ, which restricts the occurrence of electron collision ionization reactions and inhibits the propagation of plasma. The excitation energy loss of O2 is not the reason for the weakening of the plasma ionization wave. The densities of O2 +, O− and O2 − increase with the rise of O2 admixture while H2O+ decreases due to the decrease of electron density and H2O concentration. OH− density is affected by both the increase of O− and the decrease of H2O so it shows a peak in the case of O2:H2O = 7:3. O is mainly produced by the excitation reactions and the electron recombination reaction (e + O2 + → 2O), which is directly related to the O2 concentration. OH is mainly produced by e + H2O → e + H + OH so the OH density decreases due to the decrease of electron density and H2O concentration with the increase of O2:H2O ratio. On the dielectric surface, when the propagation of the streamer extinguishes, O flux shows an upward trend while the OH flux decreases, and the propagation distance of O and OH decreases with the increase of O2:H2O ratio.