Electrostatic Modes Research Articles

Two-dimensional effects on electrostatic instabilities in Hall thrusters. I. Insights from particle-in-cell simulations and two-point power spectral density reconstruction techniques

Using 2D particle-in-cell (PIC) simulations coupled to a fluid description of the gas dynamics, we study the electrostatic instabilities developing in the axial–azimuthal plane of a Hall thruster, during several periods of a low-frequency oscillation (the so-called breathing mode at 10 kHz). As done in experiments, the 2D PIC-MCC (Monte Carlo collision) code is coupled to an electrical circuit in order to partially damp the (otherwise large) discharge current fluctuations at the breathing mode frequency. The different electrostatic higher frequency modes that develop in the plasma are analyzed using a two-point power spectral density reconstruction method, which allows us to generate the dispersion diagrams (in the frequency-wavenumber space) along the axial and azimuthal directions and at different times during the low-frequency breathing mode oscillations. This technique allows us to distinguish between different well-identified instabilities: the electron cyclotron drift instability and its evolution toward an ion acoustic wave and the ion transit time instability. These instabilities are usually considered unidirectional (either axial or azimuthal); however, it is shown here that they exist in both directions. This two-dimensional character is instrumental in understanding where these instabilities grow and how they propagate in the thruster channel and plume. A theoretical discussion of this aspect is proposed in Paper II. The effects of (i) the azimuthal length of the simulation box and (ii) the electron temperature injection at the cathode are also discussed.

Two-dimensional effects on electrostatic instabilities in Hall thrusters. II. Comparison of particle-in-cell simulation results with linear theory dispersion relations

In Paper I, we successfully used an external circuit to significantly damp the Breathing Mode (BM) oscillations in 2D particle-in-cell self-consistent simulations of the axial–azimuthal plane of a Hall thruster. We also introduced the two-point power spectral density reconstruction method (PSD2P) used to analyze electrostatic instabilities and generate dispersion diagrams in azimuthal and axial directions, at various times during the BM period. Here, a 3D Dispersion Relation (DR) for electrostatic modes is calculated by linearizing the continuity/momentum fluid equations for electrons and ions. We show that by taking the appropriate limits, this relation can be simplified to derive the DRs of some well-known E×B instabilities, such as the electron cyclotron drift instability and its evolution to the Ion Acoustic Wave (IAW), and the Ion Transit-Time Instability (ITTI). The PSD2P diagrams demonstrate the importance of considering the 2D nature of the IAW and ITTI, which have been previously considered to be mono-dimensional (azimuthal and axial, respectively). In particular, we show that the IAW grows near the maximum of the magnetic field and due to its axial components propagates toward both the anode and the cathode (in addition to the well-known azimuthal propagation). The resulting wavefront is, therefore, bent. By analogy to the propagation of acoustic waves in gases, it is proposed that the cause of the IAW wavefront bending is the strong electron temperature gradients in the axial direction. We also show that the ITTI has a strong positive growth rate when a small azimuthal component is present. Finally, we observe that the ITTI significantly affects the discharge current.

Insights into divalent cation regulation and G13-coupling of orphan receptor GPR35

Endogenous ions play important roles in the function and pharmacology of G protein-coupled receptors (GPCRs) with limited atomic evidence. In addition, compared with G protein subtypes Gs, Gi/o, and Gq/11, insufficient structural evidence is accessible to understand the coupling mechanism of G12/13 protein by GPCRs. Orphan receptor GPR35, which is predominantly expressed in the gastrointestinal tract and is closely related to inflammatory bowel diseases (IBDs), stands out as a prototypical receptor for investigating ionic modulation and G13 coupling. Here we report a cryo-electron microscopy structure of G13-coupled GPR35 bound to an anti-allergic drug, lodoxamide. This structure reveals a novel divalent cation coordination site and a unique ionic regulatory mode of GPR35 and also presents a highly positively charged binding pocket and the complementary electrostatic ligand recognition mode, which explain the promiscuity of acidic ligand binding by GPR35. Structural comparison of the GPR35–G13 complex with other G protein subtypes-coupled GPCRs reveals a notable movement of the C-terminus of α5 helix of the Gα13 subunit towards the receptor core and the least outward displacement of the cytoplasmic end of GPR35 TM6. A featured ‘methionine pocket’ contributes to the G13 coupling by GPR35. Together, our findings provide a structural basis for divalent cation modulation, ligand recognition, and subsequent G13 protein coupling of GPR35 and offer a new opportunity for designing GPR35-targeted drugs for the treatment of IBDs.

Study of Interactions Between 3-benzoyl-4-hydroxy-2-methyl-2H-1, 2-benzothiazine and Human DNA by Theoretical, Spectroscopic and Viscometric measurements.

From the last few years mode of interactions between drugs and DNA is an attractive research area as it bridges chemistry, molecular biology and medicinal science. Interactions between small heterocyclic molecules and human DNA is a noteworthy feature in pharmacology for investigation of drugs mechanism and designing of more effective and target specific drugs with fewer side effects. The present research work focuses on the theoretical investigations of 3-benzoyl-4-hydroxy-2-methyl-2H-1, 2-benzothiazine (SASA) by using Gaussian (16W) software to predict optimized geometry, HOMO-LUMO gap, bond length, bond angle, dihedral angle, electronic and vibrational spectra. Possible reaction site observed in SASA was C7, C9 and C18 as these atoms show maximum charge density. Later the interactions of SASA with human DNA was explored spectroscopic investigations and viscometric investigations at physiological buffers of pH of 4.7 (stomach pH) and 7.4 (blood pH) respectively. Maximum absorbance between SASA-DNA complex was observed in buffer solution of pH 3.4 at wavelength of 370nm, whereas at 7.4 has maximim absorbance between. Spectroscopic results reflects the bathochromic and hyperchromic shift succeeding the addition of human DNA. During viscosity measurement, intercalation and electrostatic mode of interaction were detected at low and high concentration of drug in solution respectively. Increase in the value of rate constant was observed with the increase in concentration of drug. Larger values of rate constant were observed at pH 7.4 in comparison to pH 3.5. Rate constant, thermodynamic parameters and viscometric analysis prefers the intake of SASA via blood.

Взаимодействие метиленового синего с одноцепочечными полинуклеотидами poly(rA) и poly(rU) и с двухцепочечным полинуклеотидом poly(rA)-poly(rU)

Interaction of dye-intercalator methylene blue (MB) with single-stranded (ss-) polynucleotides poly(rA), poly(rU) and double-stranded poly(rA)-poly(rU) has been studied by the method of absorption spectroscopy at various concentration ratios ligand/phosphate (concentration of ss-polynucleotides by phosphate residue). It was revealed that in the absorption layer of methylene blue, in the wavelength change interval 500≤λ≤750 nm, the absorption spectra of the complexes MB-ss-poly(rA) decrease more sharply, as compared to MB spectrum, along with polynucleotide concentration enhancement in the solution. It was also revealed that the absorption spectra of the complexes MB-ss-poly(rU) decrease moderately at the increase of this polynucleotide concentration in the solution. In the spectra of the complexes MB-ss-poly(rU) a pseudo-isosbestic point is formed, while in the spectra of the complexes MB-ss-poly(rA) there is no such point. The pseudo-isosbestic point is formed also in the spectra of the complexes MB-poly(rA)-poly(rU). It was also revealed that the absorption spectra of the complexes of MB with ss-poly(rA) and poly(rA)-poly(rU) are shifted to the longer wavelengths by ~5-7 nm, while the shift in the absorption spectra of the complexes MB-ss-poly(rU) composes almost ~2 nm. The absorption spectra changes of the complexes of MB with the mentioned polynucleotides indicate that MB shows higher specificity to poly(rA), as compared to poly(rU) and poly(rA)-poly(rU). The obtained data also indicate that MB binds to poly(rA) and poly(rA)-poly(rU) by intercalation and electrostatic modes, and with ss-poly(rU) – mainly by electrostatic mechanism.

Low frequency electrostatic mode generated by electromagnetic waves in the Earth’s inner magnetosphere with two distinct electrons

The generation of low frequency electrostatic mode by parametric decay of electromagnetic waves (EMWs) in the Earth’s inner magnetosphere with exponentially truncated kappa distributed hot electrons and cold electrons is studied. Nonlinear dispersion equation for the parametric process is derived from kinetic theory. The parametric instability of EMWs decay into low frequency electrostatic normal mode (ion acoustic like wave modes and electron acoustic wave modes) and electrostatic quasi–mode in the Earth’s inner magnetosphere are numerically analyzed. It is shown that parametric instability occurs only when the EMW is sufficiently strong if the collisions between ions and electrons are taken into account. The growth rate and the threshold conditions of the decay instability depend on the concentration and distribution of hot electrons. Because they change the dispersion and the damping rate of normal mode, the collisional damping of sideband EMW. In addition, the excitation of electrostatic normal mode by parametric decay of EMWs is more difficult than the excitation of electrostatic quasi–mode. The growth rate of EMWs decaying into electrostatic quasi–mode is much larger than the ones of decaying into electrostatic normal mode. But the frequency of electrostatic quasi–mode corresponding to the maximum growth rate can be as low as a few tens Hz. The mechanism may excite the electrostatic mode with frequency comparable to those of the ultra–low frequency electric fields observed in the Earth’s inner magnetosphere.

Cascading parametric decay coupling between whistler and ion acoustic waves: Darwin particle-in-cell simulations

We present the results of numerical studies of the whistler wave parametric decay instability in the system with the suppressed Landau damping of ion acoustic waves (IAWs) based on the self-consistent Darwin particle-in-cell (PIC) model. It has been demonstrated that a monochromatic whistler wave launched along the background magnetic field couples to a counter-propagating whistler mode and co-propagating ion acoustic mode. The coupling of the electromagnetic mode to the electrostatic mode is guided by a ponderomotive force that forms spatio-temporal beat patterns in the longitudinal electric field generated by the counter-propagating whistler and the pump whistler wave. The threshold amplitude for the instability is determined to be δBw/B0 = 0.028 and agrees with a prediction for the ion decay instability: δBw/B0 = 0.042 based on the linear kinetic damping rates, and δBw/B0 = 0.030 based on the simulation derived damping rates. Increasing the amplitude of the pump whistler wave, the secondary and tertiary decay thresholds are reached, and cascading parametric decay from the daughter whistler modes is observed. At the largest amplitude (δBw/B0 ∼ 0.1) the primary IAW evolves into a short-lived and highly nonlinear structure. The observed dependence of the IAW growth rate on the pump wave amplitude agrees with the expected trend; however, quantitatively, the growth rate of the IAW is larger than expected from theoretical predictions. We discuss the relevant space regimes where the instability could be observed and extensions to the parametric coupling of whistler waves with the electron acoustic wave (EAW).

Landau damping of ion‐acoustic waves with simultaneous effects of non‐extensivity and non‐thermality in the presence of hybrid Cairns‐Tsallis distributed electrons

AbstractThe dispersion properties and Landau damping rate of ion‐acoustic waves (IAWs) with the hybrid Cairns‐Tsallis distributed (CTD) electrons and Maxwellian ions are investigated using the plasma kinetic model based on Vlasov‐Poisson's equations. For both super‐extensive (q < 1) and sub‐extensive (q > 1) plasmas, the dielectric response function, real frequency, and Landau damping rate of IAWs are derived. By taking the effect of θi, e (ion‐to‐electron temperature ratio) into account, it is found that with the increase of ion temperature, the real frequency and wave dispersion effects increase as well (for both super‐extensive and sub‐extensive cases). Exploring the properties of the Landau damping rate of IAWs with the simultaneous presence of non‐thermal parameter α and non‐extensive parameter q, a comparison of numerical and analytical results is presented. It is found that in different ranges of θe, i (electron‐to‐ion temperature ratio), on decreasing the values of the non‐extensive parameter and increasing values of the non‐thermal parameter, the weak damping rate is observed (vice versa) in super‐extensive or super‐thermal plasma, although the trend of the damping rate in sub‐thermal plasma is similar (as in the case of super‐thermal plasma) but is less weak. It is further revealed that the damping rate of IAWs in thermal plasmas (Maxwellian) is stronger than the damping rate of IAWs in the case of non‐thermal plasmas (CTD). The current study is applicable to provide deep insight and further allow the exploration of electrostatic plasma modes in different space and laboratory plasma environments where the hybrid CTD plasma exists.

The electrostatic wave modes and formation of dust voids in an externally magnetized cylindrical dusty plasma

Abstract A system of dusty plasma, containing negatively charged dust particles, Boltzmann distributed electrons and ions, is considered in a cylindrical set up and electrostatic wave modes have been studied in the presence of an external magnetic field. The dust particles are of two different sizes such that small grains are present in significant amount. Using Fourier transformation along temporal and azimuthal directions, linear dispersion relation is derived, which indicates the existence of two distinct wave modes for the stable case. Among the breathing and rotation modes, density profiles have been observed numerically for the rotation mode corresponding to the stable case. The density fluctuation of small grains is noticed to be more prominent than that of the big grains. In the presence of external magnetic field, large grains contribute very negligible magnitude of dust number density in those regions, where voids are generated by the small grains only. The effect of mode number on the dust density fluctuation as well as on the structure of density profile is observed. The magnetic field effect on dust void formation is also studied.

Imperative persistent interaction analysis of anticancer noscapine-ionic liquid with calf thymus DNA

In this study, we have shown the interaction between opium poppy alkaloid noscapine-based ionic liquid [Pip-Nos]OTf and ct-DNA using UV–visible absorption spectroscopy, fluorescence spectroscopy, CD, and computational studies. The absorption spectra showed a hypochromic shift with no shift in the absorption maxima suggesting groove or electrostatic binding. Fluorescence spectra showed an enhancement in fluorescence emission suggesting that the probable mode of binding should be groove binding. Ethidium bromide (EB) competitive and Ionic strength study showed the absence of intercalative and electrostatic modes of interaction. Further, CD analysis of ct-DNA suggested a groove binding mode of interaction of [Pip-Nos]OTf with ct-DNA. [Pip-Nos]OTf displayed a strong binding with the target ct-DNA with a molecular docking score of −41.47 kJ/mol with all 3D coordinates and full conformation. Also, molecular binding contact analyses depicted the stable binding of drug and ct-DNA with potential hydrogen bonds and hydrophobic interactions. The structural superimposition dynamics analysis showed the stable binding of [Pip-Nos]OTf with the ct-DNA model through RMSD statistics. Moreover, the ligand interaction calculations revealed the involvement of large binding energy along with a high static number of molecular forces including the hydrogen bonds and hydrophobic interactions in their complexation. These significant results report the potency of [Pip-Nos]OTf and its important futuristic role in cancer therapeutics.

Kinetic and thermodynamic studies on the interaction between calf thymus DNA and food additive vanillin - electrochemical methods

• First electroanalytical method for interaction of vanillin with calf thymus-DNA in aqueous medium. • Vanillin can bind to ds-DNA via intercalative and electrostatic binding modes. • Kinetic and thermodynamic parameters were studied for free vanillin and vanillin bounded in DNA complex and discussed. This work describes a voltammetric study on the interaction of double-stranded calf thymus DNA (ds-DNA) and the food additive vanillin. To this end, a disposable pencil graphite electrode (PGE) was used as a voltammetric probe in aqueous media. The free vanillin has an irreversible oxidation signal in acetate buffer solution, pH 4.8. The changes in this signal in the presence of ds-DNA were followed by differential pulse voltammetry (DPV). Using the data obtained by Cyclic Voltammetry (CV), the kinetic parameters, diffusion coefficient (D), heterogeneous rate constant (k s ), and electrode surface concentration ( Γ) of free vanillin was evaluated. The values of these parameters found before and after complex formation between vanillin and DNA were compared to judge the interactions. The binding constant (K) and Gibbs free energy change (ΔG°) of the interaction were found as 1.78 × 10 4 M −1 and −24.25 kJ mol −1 , respectively. The effect of ionic strength on the interaction of vanillin and ds-DNA was also investigated. The results obtained indicate the existence of an interaction between vanillin and ds-DNA. Vanillin binds to DNA both through intercalation and electrostatic attraction. The binding constant related to the vanillin-DNA interaction was comparable to the literature values found by UV–Vis studies.

Structural elucidation, in vitro DNA binding and anticancer investigations of a new specific target dinuclear Zn(II) complex

In this study, dinuclear bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate complex was synthesized and characterized by FT-IR, ESI-MS, 1H NMR and single-crystal X-ray diffraction studies. The bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate was crystallized in a monoclinic crystal system having a P 21/c space group. The single-crystal structure of bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate reveals that Zn1 is five coordinated and has adopted distorted square pyramidal geometry while as Zn2 centre is six coordinated and has adopted distorted octahedral geometry, bridged by three carboxylate groups of (2-pyrimidylthio) acetic acid (PTAA). Hirshfeld surface analysis and density functional theory were determined by crystallographic computational tools to investigate the contribution of non-covalent interactions, reactivity and stability of bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate. In vitro, ct-DNA binding studies of the complex were accomplished by applying various spectroscopic and analytical techniques. The results obtained suggested a groove or electrostatic mode of binding. The bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate has caused significant double-stranded scission of pBR322 DNA through the hydrolytic pathway as observed by the gel electrophoretic experiment. Cytotoxicity of bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate was evaluated against MCF-7, MDA-MB-231, Hop-62, AW13516 and SiHa human cancer cell lines, which revealed a moderate anticancer response. In addition, binding studies of the bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate with BSA protein were performed by fluorescence spectroscopy. The synchronous fluorescence spectra suggested the efficient binding of complex towards tyrosine than tryptophan. The quenching mechanism of BSA by complex was found static in nature.

Homotopy Study of Spherical Ion-Acoustic Waves in Relativistic Degenerate Galactic Plasma

In this work, we start with the ion-acoustic waves in galactic plasma with the degenerate matter. We use the reductive perturbation technique to derive the spherical Kadomtsev–Petviashvili (SKP) equation. We next employ homotopy-aided symbolic simulation (HASS) to study the evolution of the spherical solitary wavefront. We compare the results obtained by HPM and RPT. To understand how the system behaves, we transform the evolutionary equations into a dynamical system. The phase portraits and the superperiodic waves reflect on the intricate processes within the plasma and determine the stability criteria and possible situations of chaos. The work will find applications in many astrophysical observations, such as electrostatic wave modes, gamma-ray bursts, and double-layer solitons. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PACS</i> —95.30.Qd, 52.65.-y, 52.35.-g, 52.35.Tc.

GRACE Accelerometers Sensitive to Ionosphere Plasma Waves: Similarities between Twangs and Whistlers

Electrostatic space accelerometers are high-precision instruments used in gravity and magnetic fields and in fundamental physics missions. From their first use in space, these instruments show disturbances around the read-out frequency. In recent missions like Swarm and GRACE-FO, these instruments are seriously compromised. Their capability cannot be fully exploited or, in the worst case, not used for science data processing at all. We currently neither understand the mechanism nor the cause of the disturbance. For that reason, every correlation, direct or indirect, between signatures in the accelerometer data and other phenomena in the satellite environment is very important to study. In the GRACE mission, some of the disturbances relate to onboard current switching processes, such as switching of heater and torquer currents. In this paper, we examine the phenomena called twangs. The shape of these disturbances is responsible for their name, because they look like a decaying tone. Some of these twangs seem to relate to changing currents, too. They occur when sunlight hits surfaces of the satellite. This can cause the discharging of satellite parts. Here, we focus on special twangs, which we call cloud-related twangs, as recent investigations related them to cloud coverage. How can clouds in the troposphere influence a satellite, orbiting in the ionosphere? We investigated the troposphere–ionosphere coupling and found that the only coupling which can be responsible for disturbances on satellites and which may affect the accelerometers, are electromagnetic waves traveling in the so-called whistler mode at frequencies in the very-low-frequency (VLF) domain. This special propagation mode is a coupled electromagnetic and electrostatic mode. There, the electric field vector has a component in the direction of propagation due to the interaction with ions and the magnetic field in the ionosphere and magnetosphere. This led us to investigate the similarities between whistlers and twangs. The hypothesis that they are related is very important in our further understanding of disturbances on satellite instruments sensible to electromagnetic pulses in the range of very low frequencies and below.

Mode conversion and laser energy absorption by plasma under an inhomogeneous external magnetic field.

The interaction of a high-frequency laser with plasma in the presence of an inhomogeneous external magnetic field has been studied here with the help of particle-in-cell simulations. It has been shown that the laser enters the plasma as an extraordinary wave (X-wave), where the electric field of the wave oscillates perpendicular to both the external magnetic field and propagation direction and as it travels through the plasma, its dispersion property changes due to the inhomogeneity of the externally applied magnetic field. Our study shows that the X-wave's electromagnetic energy is converted to an electrostatic mode as it encounters the upper-hybrid (UH) resonance layer. In the later stage of the evolution, this electrostatic wave breaks and converts its energy to electron kinetic energy. Our study reveals two additional processes involved in decay of the electrostatic mode at the UH resonance layer. We have shown that the energy of the electrostatic mode at the upper-hybrid resonance layer also converts to a low-frequency lower-hybrid mode and high-frequency electromagnetic harmonic radiations. The dependence of energy conversion processes on the gradient of the external magnetic field has also been studied and analyzed.

Comprehensive structural {single crystal X-raydiffraction, spectroscopic & DFT computational simulation} and biological {in vitro DNA binding & antibacterial} studies of polymeric copper(Ⅱ)-based imidazole drug entity

A polymeric tetrakis N-imidazole copper(II) sulphate complex [Cu(imidazole)4(SO4)]n1, was synthesized and thoroughly characterized by various spectroscopic techniques, elemental analysis and single crystal X-ray crystallography. X-ray diffraction analysis confirmed that polymer complex 1 crystallized in a monoclinic C2/c space group possessing the lattice constants, a = 9.2213(1) Å, b = 17.6062(3) Å, c = 10.5710(2) Å, α = γ = 90˚ and β = 93.561˚ (1) per unit cell. Hirshfeld surface and DFT calculations were executed to simulate the electronic ground state energies in gas phase which showed that the HOMO and HOMO–1 were distributed on the axially coordinated SO42– moiety and considerable amount of electron density was present on Cu(II). Absorption and emission spectroscopic techniques were used to investigate the binding interaction of the copper(II) imidazole complex with the therapeutic target ct-DNA. The results suggested that the complex 1 binds to the ct-DNA through an electrostatic mode. The gel electrophoresis experiments of 1 were carried out with plasmid pBR322 which revealed that the polymer complex could unwind the plasmid DNA at 30 μM micromolar concentration via discernible oxidative cleavage pathway. Molecular docking studies were also carried out to support the results of DNA binding experiments. In addition, the antimicrobial potential of polymer complex was evaluated against various key pathogens viz., B. subtilis, E. coli, K. pneumonia and S. aureus. Antibiofilm behaviour of the complex 1 was examined against E. coli and S. aureus. The results demonstrated that 1 could act as an active antibacterial agent as it inhibited the bacterial growth in agar plates very efficiently.

2D distributions of potential and density mean-values and oscillations in the ECRH and NBI plasmas at the TJ-II stellarator

2D plasma potential ϕ distribution was measured in the electron cyclotron resonance heating (ECRH) and neutral beam injection (NBI) plasmas of the TJ-II stellarator with the heavy ion beam probe for the whole radial range and wide area of the poloidal angle, and supported by Langmuir probe data at the edge. The whole operation domain for the on-axis ECRH was explored ( = 0.45–0.8 ×1019 m−3, P EC = 220–470 kW), in addition, NBI plasmas with = 0.9–1.3 × 1019 m−3 and P NBI = 510 kW were studied. In ECRH plasmas the density ramp-up is accompanied by the evolution of the potential from the bell-like to the Mexican hat profile, while the density profiles were flat or slightly hollow. The potential has the positive peak at the centre, and LFS-HFS (low field—high field sides) and up-down symmetry. Equipotential lines are consistent with vacuum magnetic flux surfaces. In the high-density NBI scenario, the ϕ profile was fully negative with a minimum up to −300 V at the centre, while at low-density ECRH plasma, ϕ has a maximum up to +0.9 kV at the centre. Fluctuations of potential and density are stronger in low-density scenarios and not poloidally symmetric. At the mid-radius (area of the maximum density), root mean square (RMS) of fluctuations were up to ϕ ∼ 15 V at LFS vs ∼20 V at HFS; RMS n e ∼ 2% at LFS vs ∼3% at HFS. In the NBI plasmas with the density rise, the asymmetry decreases and finally vanishing at = 1.2 × 1019 m−3. 2D distribution of the NBI-induced Alfvén eigenmodes (AEs) shows asymmetric ballooning structure: contrary to broadband turbulence, AE-associated potential perturbation dominates in the LFS with a factor up to 1.7 respect to the HFS. The electrostatic mode, excited in ECRH plasmas by suprathermal electrons also shows asymmetric structures: density perturbation dominates in the top-bottom direction compared to LFS-HFS direction.

Synthesis, characterization and DNA binding properties of Schiff base derivatives and Ru(II) complexes

Schiff base ligands were synthesized by condensation of 5-amino-1,10-phenanthroline with 4-hydroxybenzaldehyde (L1) and decanal (L2). Ruthenium (II) metal complexes (L1-Ru(II), L2-Ru(II)) were prepared in good yield from the reaction of the ligands with the bis(2,2′-bipyridine)ruthenium(II) dichloride. Structures of synthesized compounds were characterized using elemental analyze, FTIR, UV-Visible, 1H NMR and mass spectra. The DNA-binding properties of the ligands and complexes with calf thymus DNA was investigated by spectroscopic, gel electrophoresis and viscosity measurement.The interaction of the ligands and ruthenium complexes with calf tymus DNA (CT-DNA) have been demonstrated using electronic absorption titration method. Based on the UV–Vis spectroscopy, binding constants of the synthesized compounds with CT-DNA calculated. From the results, it is observed that L1 and L1-Ru(II) bind to CT-DNA via groove binding and electrostatic mode and L2 and L2-Ru(II) bind to CT-DNA via intercalation. Kb values of L1 and L1-Ru(II) with CT-DNA were calculated as 5.2 × 105 M−1 and 4.8 × 106 M−1, respectively. Absorption spectral study indicated that L2 and L2-Ru(II) have intrinsic binding constant (Kb) in the range of 3.8 × 105 -3.7 × 106 M−1. The results show that the complexes have more binding ability than the ligands.

Functionalized graphene oxide loaded GATPT as rationally designed vehicle for cancer-targeted drug delivery

This study focused to demonstrate the impact of the anticancer activity of nanoparticles of 1-{(2-hydroxyethyl) amino}-2-amino-1,2-dideoxy-d-glucose triphenyltin (IV) (GATPT) by using graphene oxide as a drug carrier. The synthesized GATPT was loaded on GO, which was prepared by the simple ultrasonication method. The successful loading of GATPT on GO was characterized by utilizing various physicochemical techniques, and the results showed that the encapsulation of GATPT on GO occurred via π–π stacking and electrostatic mode of interaction. The interaction of GATPT-GO with ct-DNA has been explored by employing absorption, emission, circular dichroic spectral methods, and cyclic voltammetry (CV). The corroborative results of all these techniques along with molecular docking suggested the electrostatic mode of interaction of GATPT-GO towards DNA. Cleavage activity was performed by gel electrophoretic assays which indicated that GATPT-GO cleaves pBR322 via hydrolytic pathway in the presence of EtOH as an active species. The cytotoxic studies of GATPT-GO were evaluated against human prostate cancer (DU145) cell lines and liver carcinoma (Huh-7) cell lines, including normal cell lines (PNT2). These experiment results revealed significant cytotoxic activity against Du145 cancer cells than the Huh-7 cancer cells and were found nontoxic toward the PNT2 cells at a lower concentration. Also, image analysis was performed by confocal microscopy. The results obtained from confocal microscopy provide clear evidence of endocytosis of GATPT, revelling that the released drug (GATPT) from carrier (GO) has specifically entered into the cell nucleus.

Physicochemical and computational investigations of some food chemicals prevalent in aqueous 1-butyl-1-methyl-pyrrolidinium chloride solutions with the manifestation of solvation consequences

An investigation on the diverse molecular interactions between implausible food chemicals (potassium oxalate, sodium oxalate and lithium Oxalate) and 1-butyl-1-methyl-pyrrolidinium chloride in aqueous solutions has been presented. The experiments have been discovered thoroughly by different types of physicochemical methodologies like density, refractive index, viscosity, and electrical conductivity at three different temperatures 298.15 K, 308.15 K and 318.15 K. The genesis of diverse interactions of the ternary mixtures were exposed by measurement of the apparent molar volume (ϕv), limiting apparent molar volume (ϕv0), viscosity B coefficients, molar refraction (RM), limiting molar refraction (RM0). The results have been revealed the predominant solute–solvent interaction over the solute–solute as well as solvent–solvent interactions. The ionic liquid strongly interacts with potassium oxalate than sodium oxalate, which in turn is greater than lithium oxalate at a higher range of temperature. Moreover Density functional theory calculations were performed to evaluate parameters like adsorption energies, molecular electrostatic potential maps and mode of binding which corroborate the experimental observations.