PD Charge Research Articles

Cytotoxicity and Apoptosis-Induction in MCF-7 Cells for New Pd(II) Complex Based on s-Triazine Ligand: Synthesis, Single Crystal X-ray Diffraction Analysis and Structural Investigations

The synthesis and X-ray structure analysis of the new [PdLCl2]*0.5 CH2Cl2 complex where L is hydrazono-s-triazine di-morpholine derivative, were presented. In the neutral inner sphere of this complex, the organic ligand L is acting as a NN-bidentate chelate via the pyridine and hydrazone N-atoms. The coordination configuration of the Pd(II) is completed by two chloride ions at cis-positions. The tetra-coordinated Pd(II) showed a distorted square planar geometry. The outer sphere comprised half methylene chloride molecule per [PdLCl2] as crystal solvent. The crystal stability is dominated by a number of weak C-H…N, C-H…Cl, and C-H…O non-covalent interactions. Based on Hirshfeld analysis, the H…H, N…H, H…Cl, O…H, Pd…C, and Cl…C intermolecular interactions contributed by 45.2, 9.3, 21.5, 5.8, 2.3, and 3.4%, respectively. DFT studies revealed closed shell characters for the Pd-N and Pd-Cl coordinate bonds. The net charge of Pd is also predicted to be 0.311 e and the amount of electron density transferred from the ligand groups is 1.689 e. The Pd(II) complex exhibited potent cytotoxic activity against MCF-7, HepG2, and A549 cells with IC50 values of 1.18, 4.74, and 5.22 μg/mL, compared to cisplatin with IC50 values of 4.1, 9.7, and 12.3 μg/mL, respectively. Additionally, it exhibited poor cytotoxicity against WISH cells with much higher IC50 values (IC50 = 37.2 μg/mL). Investigating apoptosis-induction, the Pd(II) complex induced apoptotic cell death by an 11-fold change in MCF-7 cells arresting the cell phase at the G0–G1 phase. Accordingly, Pd(II) complex can be developed as a promising anti-breast cancer agent.

Breaking scaling relationships in alkynol semi-hydrogenation by manipulating interstitial atoms in Pd with d-electron gain

Pd catalysts are widely used in alkynol semi-hydrogenation. However, due to the existence of scaling relationships of adsorption energies between the key adsorbed species, the increase in conversion is frequently accompanied by side reactions, thereby reducing the selectivity to alkenols. We report that the simultaneous increase in alkenol selectivity and alkynol conversion is achieved by manipulating interstitial atoms including B, P, C, S and N in Pd catalysts. A negative linear relationship is observed between the activation entropies of 2-methyl-3-butyn-2-ol and 2-methyl-3-buten-2-ol which is highly related to the filling of d-orbital of Pd catalysts by the modification of p-block elements. A catalyst co-modified by B and C atoms has the maximum d charge of Pd that achieves a 17-fold increase in the turn-over frequency values compared to the Lindlar catalysts in the semi-hydrogenation of 2-methyl-3-butyn-2-ol. When the conversion is close to 100%, the selectivity can be as high as 95%.

Examination on Partial Discharge Characteristics and Frequency Acceleration Equivalence till Breakdown for Nanocomposite Enamel Wire

This paper presents partial discharge characteristics and film thickness wear till dielectric breakdown under bipolar repetitive impulse voltage application to twisted pair enamel wire added with nano-size boehmite to polyimide (PI) resin by comparing with a sample without the addition. The frequency acceleration equivalence of the life time and PD characteristics till breakdown is also examined. As a result, it was found that at frequencies 10 kHz to 30 kHz, a frequency acceleration equivalence held in terms of the total amount of PD charge at an applied voltage Va = 1.5 kV, while it did not at Va = 3.0 kV due to severer heat generated by PD. In addition, it was found that the coating thickness erosion of boehmite PI was less likely to be caused than that of neat PI under the same experimental conditions. Consequently, it is indicated that the total PD charge amount is closely related with the coating erosion speed.

The rule of N in N-doped graphene supported Pd catalyst

Using first-principles calculations, the rule of N in N-doped graphene supported Pd catalyst was investigated. Our results show that the doped N enhanced the adsorption and charge of Pd, which can lead to higher catalytic activity. Meanwhile, the doped N can also enhance the adsorption of H and make it more difficult to migrate on graphene. But the doped N is conductive to overflow of H from the Pd to graphene, the energy barrier is reduced from 1.01 eV to 0.85 eV. Therefore, it is speculated that one migration path of H on the N-doped graphene through the Pd atom.

Preparation of MoS2 nanosheets to support Pd species for selective steerable hydrogenation of acetylene

Selective hydrogenation of acetylene to ethylene while avoiding over-hydrogenation into ethane is challenging for polymer industry. For highly steerable catalyst design of Metal-MoS2, we reported a few-layer nano-MoS2 supported Pd catalyst, in which the support was prepared by the exfoliation method of bulk molybdenum disulfide (MoS2) in formamide solution. The results from TEM, SAED, AFM and Raman spectra analysis confirmed that the few-layer nano-MoS2 was produced successfully. The XPS result indicates Pd charge transferred to MoS2, proving strong Pd-MoS2 interactions. Pd/nano-MoS2 provided a good catalytic performance for the hydrogenation of acetylene to ethylene, and the ethylene selectivity can reach up to 75% while acetylene conversion can achieve nearly 100%. Comparing with the commercial 5% Pd/C catalyst reported at similar conditions, the Pd/nano-MoS2 synthesized in this study presents better activity and selectivity. In all, this work shows potential application of MoS2 nanosheets used as catalyst support to achieve selective steerable reactions.

"On Water" Palladium Catalyzed Direct Arylation of 1H-Indazole and 1H-7-Azaindazole.

The C3 direct arylation of 1H-indazole and 1H-7-azaindazole has been a significant challenge due to the lack of the reactivity at this position. In this paper, we describe a mild and an efficient synthesis of new series of C3-aryled 1H-indazoles and C3-aryled 1H-7-azaindazoles via a C3 direct arylation using water as solvent. On water, PPh3 was effective as a ligand along with a lower charge of the catalyst Pd(OAc)2 (5 mol%) at 100 °C, leading to C3-aryled 1H-indazoles or C3-aryled 1H-7-azaindazoles in moderate to good yields.

Measurable surface d charge of Pd as a descriptor for the selective hydrogenation activity of quinoline

AbstractAuPd nanoalloys with tunable Pd concentrations have been synthesized and used as model catalysts. They have been directly imaged by high-angle annular dark-field scanning transmission electron microscopy and investigated by thorough analyses of their extended X-ray absorption fine structure, X-ray absorption near-edge structure, X-ray diffraction and X-ray photoelectron spectroscopy measurements. The bimetallic nanoparticles are embedded in a carbonaceous matrix and have almost an identical structure at the atomic level and the same electronic properties as AuPd bulk alloys with the same compositions. The d-electron increase at surface Pd sites is determined by the Pd concentration of the alloy. Similarly, their activation entropy and catalytic activity for the hydrogenation of quinoline is related to the Pd concentration, with Au50Pd50 the most active of the alloys investigated. An almost 11 times higher activity was achieved compared to a pure Pd catalyst. The experimentally measurable surface d charge at the Pd sites in the AuPd was found to linearly correlate with the activation entropy and catalytic activity for the hydrogenation of quinoline. The alloy structure is stable, showing negligible metal segregation, dissolution-redeposition and aggregation during the hydrogenation process which involves strong adsorption.

Вплив складу шихтових матеріалів порошкових дротів на механічні характеристики та корозійну стійкість електродугових покриттів

The influence of charge materials of flux-cored wires on their mechanical characteristics, chemical microheterogeneity and corrosion resistance in an aqueous solution of 3% NaCl was established. It is shown that, in contrast to coatings made of solid wires, coatings sprayed using flux-cored wires (PO) have a high chemical heterogeneity. This is due to the fact that the droplets that disperse from the PD melt and form a coating have different chemical compositions. This is caused by incomplete fusion of the charge and steel shell at the ends of the PD during electric arc spraying of coatings. To reduce the chemical micro-heterogeneity, it is proposed to add powders of ferroalloys FeSi, FeMn and self-flux PG-10H-01 to the charge of powder wire containing chromium, boron, carbon-containing components (Cr, FH, PG-100, B4C, FCB) between the components of the charge, homogenize the melt of PD and, as a consequence, reduce the microheterogeneity of the coatings. The presence of chromium, ferrochrome, ferro-silicon and ferromanganese in the charge of PD 90Х17РГС and PD 75Х19Р3ГС2 determines the minimum chemical microheterogeneity of coatings from these wires and, as a result, ensures their high corrosion resistance, which is close to corrosion steel18. To increase the completeness of fusion of the components of the PD charge between itself and its steel shell, it is proposed to add to the PD charge powders of ferroalloys Fe-Mn, Fe-Si, which have a low melting point, able to interact with refractory components of the charge to form low-temperature eutectics. The addition of ferro-silicon, ferromanganese and self-flux alloy PN-10H-01 powders based on ferrochrobor and ferrochrome provided high hardness of electric arc coatings, low heterogeneity in terms of chromium content in coating lamellae and, as a consequence, high corrosion resistance.

Technique for discriminating the type of PD in SF<sub>6</sub> gas using the UHF method and the PD current with a metallic particle

The relationship between the PD current pulse waveform at the PD source and the radiated electromagnetic (EM) waveform is investigated using a needle electrode for a metallic particle in SF6 gas at 0.2MPa. A leader discharge with a larger PD charge magnitude and a longer propagation length than for a streamer discharge can be an indicator of breakdown in the SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas. Simultaneous and synchronous measurement of the PD current, EM signals and light emission in the SF6 gas revealed that it is possible to discriminate between a streamer discharge and a leader discharge in both time and frequency components. Compared with a streamer discharge, a leader discharge is characterized by a longer rise/fall time of around 0.9 ns in the PD current pulse waveform, and by a lower frequency component of around 250 MHz in the EM frequency spectrum. A satisfactory correlation was obtained between the actual measured EM wave spectrum and the spectrum derived using a spectrum analyzer from the product of the actual PD current and the transfer function from the needle electrode to the UHF sensor that receives the EM wave. This new technique enables streamer and leader types of PD in SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas to be discriminated between by measuring the EM wave with a UHF detection system.

Change in partial discharge activity as related to degradation level in oil-impregnated paper insulation: effect of high voltage impulses

High voltage (HV) transients in electrical power systems are mainly caused by lightning strikes and switching operations. The dielectric properties of a particular electrical insulation at the instant of interaction with a high voltage transient would determine a level of the degradation of an electrical insulation. This work investigates how high voltage impulses would change Phase Resolved Partial Discharge (PRPD) patterns in test samples consisting of a cavity deliberately introduced between the sheets of oil-impregnated paper used in power transformer bushings. It also investigates how the change in PRPD patterns is related to the degradation level of oilimpregnated paper. In order to accomplish these objectives, the experiments were set in such a way that the effect of HV impulses and an early stage PD activity at an elevated AC stress, HV impulses in combination with a prolonged PD activity at an elevated AC stress, and a prolonged PD activity alone at an elevated AC stress could be investigated separately. The experimental results presented in this paper indicate that HV impulses below the impulse breakdown stress following an early stage AC PD activity would not cause a significant change in PRPD patterns, and would not damage oil-impregnated paper to a level which can be noticed by a visual observation. On the other hand, a prolonged AC PD activity alone can cause the change in PRPD patterns, but cannot quickly damage the oil-impregnated paper as it would do when it is combined with HV impulses. However, the combination of both, HV impulses and a prolonged AC PD activity caused a high drop in the PD parameters (total PD charge and a repetition rate). The study found that the decrease of the PD parameters can be considered as a sign of severe degradation of oil-impregnated paper.

Effect of Test Method and Needle Plane Configuration on Partial Discharge Inception Voltage Measurement of Mineral Oil based on Weibull Analysis

Abstract The discussion of test method and electrode configuration for Partial Discharge Inception Voltage (PDIV) measurement is continuously developed because the PDIV can be used as indicator to determine condition of insulating liquid. However, many researchers investigate the PDIV using different test method and electrode configurations. This paper discusses the effect of test methods and needle to plane electrode configuration on the PDIV measurement of mineral oil as insulating liquid. The mineral oil that used in experiment test was Nynas Nitro 4000x with water content less than 10 ppm. In experiment, the test circuit was set up according to IEC 60270. The first test method that was carried out in this experiment according to IEC 61294 with ramp rate of test voltage 1 kV/s until PDIV occurred. Meanwhile, a Combine Method as the second test method was used as comparative PDIV test technique for this experiment. With this combine method, the test voltage was applied to the test object with rate 1 kV/s until 70% of the PDIV value obtained from the first test method. Then the test voltage was increased in steps with 1 kV/step with step duration of 1 minute until PDIV obtained with PD charge ≥ 100 pC. The rest time between consecutive tests was 5 minutes. The needle tip radii that used as high voltage electrode were 10 μm and 20 μm, meanwhile brass plane electrode with diameter 50 mm was used as the grounded electrode. In this paper, the electric field stress of the needle to plane electrode was calculated using Finite Element (FEM) simulation with input voltage 100 volt. The test result was analyzed using Weibull distribution to calculate the Cumulative Distribution Function (CDF) and Probability Density Function (PDF) of PDIV value. The calculation results show that the test results agree with Weibull distribution.

Tuning the Oxygen Reduction Activity of Pd Shell Nanoparticles with Random Alloy Cores

Pd-based nanoparticles are promising candidates for non-Pt catalysts of the oxygen reduction reaction (ORR). Trends in ORR activity of Pd/Cu-alloy-core@Pd-shell nanoparticles are studied by calculating the oxygen binding energy on the Pd surface with different Cu compositions in the alloy core. Density functional theory calculations show that several properties of the nanoparticle surface, including the average oxygen binding energy, d-band center, and the net charge of Pd, are linearly related to the ratio of Cu in the core, demonstrating the capacity to tune ORR activity. Trends in oxygen binding of other core alloys are also studied and show similar linear trends with core composition, providing a design strategy for new ORR catalysts.

Partial discharge parameters to evaluate the insulation condition of on-line located defects in medium voltage cable networks

Partial discharge analysis has a long record as reliable diagnostic tool to assess the integrity and the quality of electrical insulation of power systems. On-line partial discharge monitoring systems for live medium voltage cable connections have recently been introduced in Dutch grids and also a few worldwide. To enhance the applicability of on-line cable diagnostics there is a need to develop a PD interpretation approach suitable for on-line monitoring. This paper discusses various PD parameters, including PD charge magnitude, PD occurrence rate and PD charge density and their related statistical values such as mean and maximum, used to interpret the PD activity. Trend watching of these parameters is employed to study the degradation state of cable connections and their components. The approach is applied to field data obtained over a year through monitoring several live circuits. In this paper, three examples are presented. Weak spots were detected and failures were prevented by early warning.

DFT study of difference caused by catalyst supports in Pt and Pd catalysis of oxygen reduction reaction

Based on an experimental phenomenon that catalytic activity of Pt and Pd for oxygen reduction reaction (ORR) changes with catalyst supports from C to TiO2, density function theory (DFT) was used to elucidate the cause behind the difference in catalysis caused by catalyst supports. First, factors closely associated with the first electron transfer of the ORR were assessed in the light of quantum chemistry. Then intermediate (atomic oxygen, O) adsorption strength on the catalyst surface was calculated. The results show that, in terms of minimum energy difference, the best orbital symmetry match, and the maximum orbital overlap, TiO2 does bring about a very positive effect on catalysts Pd/TiO2 for the first electron transfer of the ORR. Especially, TiO2 remarkably expands the space size of Pd/TiO2 HOMO orbital and improves orbital overlap of Pd/TiO2 HOMO and O2 LUMO. The analysis of deformation density and partial density of state shows that the strong interaction between Pt and Ti leads to a strong adsorption of intermediate O on Pt/TiO2, but the strong interaction between Pd and surface O causes positive net charge of Pd and a weak adsorption of intermediate O on Pd/TiO2. Thus, the ORR can proceed more smoothly on Pd/TiO2 than Pt/TiO2 in every respect of maximum orbital overlap and rate delay by intermediate O. The research also discloses that several factors lead to less activity of TiO2-supported Pt and Pd catalysts than the C-supported ones for the ORR. These factors include the poor dispersion of Pt and Pd particles on TiO2, poor electric conduction of TiO2 carrier itself, and bigger energy difference between HOMO of TiO2-carried metallic catalysts and LUMO of O2 molecule due to electrons deeply embedded in the semiconductor TiO2 carrier.

Application of error‐ranked singular value decomposition for the determination of potential‐derived atomic‐centered point charges

The present work provides a detailed investigation on the use of singular value decomposition (SVD) to solve the linear least-squares problem (LLS) for the purposes of obtaining potential-derived atom-centered point charges (PD charges) from the ab initio molecular electrostatic potential (V(QM)). Given the SVD of any PD charge calculation LLS problem, it was concluded that (1) all singular vectors are not necessary to obtain the optimal set of PD charges and (2) the most effective set of singular vectors do not necessarily correspond to those with the largest singular values. It is shown that the efficient use of singular vectors can provide statistically well-defined PD charges when compared with conventional PD charge calculation methods without sacrificing the agreement with V(QM). As can be expected, the methodology outlined here is independent of the algorithm for sampling V(QM) as well as the basis set used to calculate V(QM). An algorithm is provided to select the best set of singular vectors used for optimal PD charge calculations. To minimize the subjective comparisons of different PD charge sets, we also provide an objective criterion for determining if two sets of PD charges are significantly different from one another.

Preparation and electrochemical characterization of palladium single crystal electrodes in 0.1 M H 2SO 4 and HClO 4: Part I. Low-index phases

The electrochemical properties of Pd(1 1 1), Pd(1 0 0) and Pd(1 1 0) single crystal bead electrodes, prepared by a novel electron beam heating and inductive annealing technique, have been characterized in 0.1 M sulfuric acid and 0.1 M perchloric acid by cyclic voltammetry and chronoamperometry. Hydrogen and (hydrogen) sulfate adsorption as well as surface oxidation were found to depend strongly on the crystallographic orientation and the nature of the electrolyte. The combination of charge displacement and voltammetric experiments allowed the determination of the potentials of zero total charge ( E pztc) of Pd(1 1 1) and Pd(1 0 0). The values of E pztc in sulfuric acid were found to be more negative than in perchloric acid. The estimation of E pztc for Pd(1 1 0) was hampered by the superposition with hydrogen absorption. The electro-oxidation of irreversible adsorbed carbon monoxide monolayers was studied on the three low-index Pd electrodes. The onset potential of the CO oxidation reaction follows the sequence Pd(1 0 0) < Pd(1 1 0) < Pd(1 1 1). Chronoamperometric experiments revealed a pronounced structure sensitivity of the reaction kinetics. The processes involved are determined by nucleation of oxygen-containing species on defect (step) sites and by slow diffusion of CO ads on (1 1 1) terrace sites.

The potentials of zero charge of Pd(1 1 1) and thin Pd overlayers on Au(1 1 1)

The potential of zero charge (pzc) of Pd(1 1 1) has been determined in dilute NaF solutions by measuring the Gouy–Chapman minimum of the double-layer capacity. For a massive Pd(1 1 1) single crystal electrode a pzc of −0.12 V vs. SCE has been found. The corresponding values for thin Pd(1 1 1) overlayers on Au(1 1 1) have also been determined. While the pzc of the first, pseudomorphic Pd layer on Au(1 1 1) is −0.09 V vs. SCE, the pzc of a five monolayers thick Pd film on Au(1 1 1) is practically identical to the pzc of the massive Pd(1 1 1) electrode. By comparing pzc's and work functions for Au(1 1 1) and Pd(1 1 1), the dipole contribution to the potential drop across the Pd(1 1 1)/water interface is estimated.

Partial discharge inception characteristics of LN 2/epoxy composite insulation system under thermal bubble condition

In this paper, we investigated electric field strength at partial discharge inception (PDIE) in liquid nitrogen (LN 2)/epoxy composite insulation system with thermal bubbles under atmospheric and pressurized conditions. We measured PDIE and PD charge, and simultaneously observed diameter and number of the bubbles and their behavior using a high-speed video system of 200 frames/s. PDIE characteristics were analyzed using the Weibull statistics. The pressure dependence of bubble diameter, PD charge and scale parameter of PDIE was systematized under different thermal bubble conditions. Experimental results revealed that (1) PD was initiated in thermal bubbles in LN 2, (2) scale parameter of PDIE decreased with the increase in V rate defined as the volume ratio of the thermal bubbles to the gap space and (3) PDIE was found to mutually depend on not only V rate but also gas density in the thermal bubbles.

Oxidation of Sn overlayers and the structure and stability of Sn oxide films on Pd(111)

The oxidation at 300 K of ultrathin Sn films has been studied by Auger and x-ray photoelectron spectroscopy. The process divides into two regimes: submonolayer Sn coverages are stable towards low $(&lt;{10}^{5}\mathrm{L})$ oxygen exposures, becoming fully oxidized to stoichiometric SnO at higher exposures $(\ensuremath{\sim}{10}^{11}\mathrm{L}).$ Thicker Sn deposits oxidize more rapidly, and analysis of the Sn Auger parameter and substrate surface core-level shift indicates that oxidation is accompanied by relatively little change in the initial state charge density of the Sn atoms. This reflects strong preexisting Sn to Pd charge transfer and the low dimensionality of the oxidized Sn overlayers. Thermal stability of these films increases with thickness and they decompose by evolution of gaseous oxygen accompanied by Pd/Sn surface alloy formation. The strong Pd-Sn chemical bond exerts a controlling influence on both overlayer oxidation and oxide decomposition processes within the Sn/Pd(111) system.

Carborane to enhance chelating capacity S,S′-thioether— thioester coordination and its transition metal stability

An S,S′-thioether—thioester chelating ligand [7,8-μ-SCH2C(O)S-7,8-C2B9H10]− (L1), incorporating the unit [—(C)2B9H10]− has been synthesized. Reactions have been conducted with RhCl(PPh3)3 and PdCl2(PPh3)2 complexes in ethanol. With Rh, L1 maintains its original cyclic nature and most probably chelation via thioether—thioester takes place. The carborane negative charge may stabilize this original thioether—thioester complex. The other two Rh positions are occupied by two PPh3 ancillary ligands forming [Rh(L1)(PPh3)2]. The reaction of L1 with Pd induces ligand modifications and the cyclic nature of L1 is lost. A transesterification process leading to a dianionic ligand L2, [7-S-8-SCH2C(O)OCH2CH3−7,8-C2B9H10]2− has taken place. In this way L2 is capable of compensating the dipositive Pd charge. The other two Pd positions are occupied by two PPh3. This reaction has been extended to methanol and isopropanol solvents. The crystal structure of [Pd(L2)(PPh3)2] has been determined.