Dipole Moment Constant Research Articles

Dissolved ammonia catalyzes proto-dolomite precipitation at Earth surface temperature

Marine carbonate rocks are the major reservoir of carbon through CaCO3 and CaMg(CO3)2 precipitation extracting CO2/HCO3- from the atmosphere/oceans; hence dolomite is one of the major sinks in the global carbon cycle. Most ancient dolomite has been considered as mainly precipitated under Earth surface conditions. Previous studies have demonstrated that microbes can mediate dolomite formation. However, the “microbial dolomite” model is not sufficient to explain the dolomite that shows no or little evidence of a microbial origin. Although attempted for decades, the synthesis of inorganically-produced dolomite at normal temperatures (<50 °C) has been relatively unsuccessful. Hence, this "dolomite enigma" has been one principal research focus this century. Here we demonstrate that NH3 catalyzes proto-dolomite precipitation inorganically with higher Mg/Ca molar ratios and CO32- activity at normal temperatures of 30 °C and 40 °C. NH3 dissolution increases the alkalinity of the solution and transformes into NH4+ ions, which prefer to bond with H2O on Mg[(H2O)6]2+ rather than free H2O, thus releasing Mg2+ to facilitate proto-dolomite nucleation. Furthermore, the low dielectric constant and low dipole moment allow NH4+ absorbed on crystal surfaces to lower the energy barrier of Mg[(H2O)6]2+ dehydration, promoting proto-dolomite nucleis growth. The system for proto-dolomite precipitation in our experiments closely simulates the natural aqueous environment. This study brings new insights to understanding the mechanisms of dolomite precipitation in natural waters.

POWER SUPPLY UNIT OF THE STAND AND LABORATORY INSTALLATION FOR TREATING OLIVES WITH ELECTROSTATIC FIELD

Most technological machines (TM) use hydraulic drives and internal combustion engines, such as lifting and transporting, loading and unloading, construction, road, track, and mining. Increasing the durability of the specified TM units is an urgent task. One of the possible solutions to this urgent problem is the electrostatic treatment of hydraulic oils and diesel fuels. Over the past three decades, researchers have conducted many studies focused on finding optimal means of using external force fields to improve the quality of lubricating materials and intensify their production. Types of influence of force fields, such as mechanical, mechanochemical, acoustic, electromagnetic, and electric, are increasingly used to regulate the behaviour of dispersed particles in nonpolar and slightly polar environments. The theory of regulated interphase transitions proves that the emergence, growth, and size change of supramolecular structures, surrounded by an adsorption-solvate layer and creating complex structural units in oil dispersion systems, contribute to the emergence of new properties of these systems. One of the main provisions of this theory is the need for extreme and antibating changes in the size of complex structural units with the help of external influences, which include force fields. Lubricating materials differ in their degrees of dispersity, composition, and properties, so the effect of force fields on them is diverse. The ability to regulate intermolecular interactions and the size of complex structural units are significant in the operation of lubricants. Electric fields make it possible to control phase interactions in these dispersed systems: they increase the constant dipole moments of particles and the electrosurface forces, which contribute to the deformation of the electric double layer. Under the action of strong electric fields, structural changes occur in hydrocarbon dispersion systems, which significantly change the physicochemical properties of lubricating materials. Thus, the dynamic viscosity of the lubricant and its resistance to deformation may change depending on the chemical nature of the system. Previously conducted experimental studies allow us to formulate the requirements for the stand in detail, which enables investigation of the properties of petroleum-based liquids. Thus, it is possible to achieve increased anti-wear properties of petroleum-based liquids when the liquid passes through the gap between the electrodes in an electrostatic field. The voltage between the electrodes should be U = 1000–1500 V, and the speed of the liquid movement in the space between the electrodes should be V = 4.5–6.5 m/s. The power supply unit of the stand for electroprocessing petroleum-based liquids, proposed in this paper, meets these requirements. The article proposes a fundamentally new scheme for the power supply unit of the laboratory stand for direct current electrotreatment of petroleum-based liquids. The power supply unit is a bipolar source of adjustable direct current. It provides smooth regulation of the voltage from 0 to 3000 V and step regulation of the output current. The block has double protection against short circuits at the output and input. Keywords: anti-wear property, oil, influence of an electrostatic field on the anti-wear properties of oil, device for electrostatic treatment of oil.

Extraction of N- and S-compounds in gasoline and diesel from ionic liquids: A molecular dynamics study

The extraction of nitrogen and sulfur compounds from gasoline and diesel, using ionic liquids, is conducted through liquid-liquid molecular dynamics simulations. The novel united atom parameters of pyridine, benzene and thiophene which possess a constant dipole moment successfully reproduce the experimental dielectric constant and solubility in water. These molecular parameters are transferred to simulate toluene and dibenzothiophene. Regarding polar liquids, the coexisting densities and surface tension as functions of temperature align excellently with experimental data. The liquid density and surface tension of modeled diesel and gasoline also match experimental data well although the viscosity is underestimated. Ionic liquids comprise positive ions of imidazolium, pyrrolidinium, pyridinium and trimethyl ammonium varying in hydrocarbon chain length. The anion is bis(trifluoromethylsulfonyl)imide. It has been discovered that the new parameters significantly enhance the extraction of nitrogen and sulfur compounds from hydrocarbon mixtures compared to simulation results from TraPPE-UA force field where the molecules possess zero molecular dipole moment. The extraction efficiency of ionic liquids aligns excellently with experimental results at room temperature.

Advancements and challenges in molecular/hybrid perovskites for piezoelectric nanogenerator application: A comprehensive review

Molecular perovskites are a class of materials that have attracted considerable attention in recent years due to their unique physical characteristics, structural properties, and diverse applications. These materials are also known as Hybrid Organic-Inorganic Perovskite (HOIP) and are denoted by the general formula ABX3. HOIP materials feature an organic or inorganic molecular cation (A), a metal or molecular cation (B), and a molecular anionic bridging ligand (X). The perovskite structure comprises BX6 octahedra that share corners, forming a three-dimensional network. The remarkable properties of molecular perovskites arise from their intrinsic polarization, resulting from the presence of polar organic cations in hybrid perovskites that possess a constant electric dipole moment. The alignment of these dipoles plays a crucial role in the properties of molecular perovskites. Consequently, this polarization can be harnessed to capture ambient mechanical energy and convert it into electrical energy. This review paper provides a comprehensive overview of molecular perovskites, focusing on their physical characteristics, synthesis methods, and multifunctional applications, particularly in piezoelectric nanogenerators. Furthermore, it addresses the challenges and opportunities associated with boosting their piezoelectric performance and integrating them with nanogenerator technology and flexible devices. Recent advances and breakthroughs in molecular perovskite-based nanogenerators are highlighted, including lead-free, metal-free, double perovskite materials, etc. Finally, the paper proposes future directions and perspectives for further research and innovation in this dynamic field.

Gadolinyum(III) Asetat İçeren Yeni Tetrapirazinoporfirazinin Sentezi ve Spektroskopik Özellikleri

A new tetrakis-(2-methylpyrazino)porphyrazinato gadolinium(III) acetate complex was synthesized. Elemental analysis, Fourier-Transform Infrared, Ultraviolet-visible, and fluorescence spectroscopy techniques clarified its structure. It can dissolve very well without aggregation in both Dimethyl sulfoxide and N, N-Dimethylformamide, which have high dielectric constant and high dipole moment from polar aprotic solvent type. Its aggregation property was also investigated in dimethyl sulfoxide at different concentrations, and it was determined to contain monomeric species. In addition, its fluorescence properties were investigated in Dimethyl sulfoxide and the effect of gadolinium(III) acetate metal ion as a heavy rare earth element was determined. According to the findings in this study, it may be used as an electronic and optical material and in various technological applications such as photocatalytic applications. In addition, these findings may be useful for systems that include changes in pyrazinoporphyrazine-like forms.

Radiation of a Solitary Polarization Pulse Moving at the Speed of Light

Photons have zero rest mass and always travel at the speed of light in a vacuum, but have no dipole moment. Atoms and molecules, which may have a constant or variable dipole moment, have mass and therefore cannot move at or above the speed of light. As a result, the radiation from such systems moving at the velocity of light was not considered. However, it is possible to create many artificial objects (light spots, effective charges, current pulses, etc.) that can travel at the speed of light and even exceed it. In this case, they become a source of electromagnetic radiation. In this work, the radiation of a solitary polarization pulse that travels at the speed of light and has a variable or constant amplitude is discussed. It is shown that if the amplitude does not change, then such an object does not radiate outward; i.e., the field emitted by it remains completely localized inside the moving polarization pulse. If the amplitude changes over time, then it begins to radiate backwards. In this case, unipolar pulses of an unusual shape, such as a rectangular one, can be obtained.

Radiation of a Solitary Polarization Pulse Moving at the Speed of Light

Photons have zero rest mass and always travel at the speed of light in a vacuum, but have no dipole moment. Atoms and molecules, which may have a constant or variable dipole moment, have mass and therefore cannot move at or above the speed of light. As a result, the radiation from such systems moving at the velocity of light was not considered. However, it is possible to create many artificial objects (light spots, effective charges, current pulses, etc.) that can travel at the speed of light and even exceed it. In this case, they become a source of electromagnetic radiation. In this work, the radiation of a solitary polarization pulse that travels at the speed of light and has a variable or constant amplitude is discussed. It is shown that if the amplitude does not change, then such an object does not radiate outward; i.e., the field emitted by it remains completely localized inside the moving polarization pulse. If the amplitude changes over time, then it begins to radiate backwards. In this case, unipolar pulses of an unusual shape, such as a rectangular one, can be obtained.

Distribution of Weakly Interacting Atoms and Molecules in Low-Temperature Amorphous Solid Water.

Understanding the distribution and mixing of atoms and molecules in amorphous solid water (ASW) at low temperatures is relevant to the exploration of the astrochemical environment in the interstellar medium (ISM) that leads to the formation of new complex molecules. In this study, a combination of temperature programmed desorption (ΔP-TPD) experiments and Ne+ ion sputtering is used to determine the extent of mixing and distribution of guest atoms and molecules within thin ASW films deposited at 35 K on a Ru(0001) substrate, prior to sputtering. The mixing of krypton atoms and methyl chloride molecules within thin ASW films is directed by the physical properties of the respective species and the nature of their interaction with the host water molecules. While the Kr-H2O interaction may be described as a weak van der Waals attraction, the CD3Cl-H2O interaction can be characterized as weakly hydrophobic in nature. This leads to differences in the level of homogeneity in mixing and distribution of the guest species in the ASW film. Both krypton atoms and methyl chloride molecules reveal a propensity to migrate toward the ASW-vacuum interface. The krypton atoms migrate through both diffusion and displacement by incoming H2O molecules, while the methyl chloride molecules tend to move toward the vacuum interface primarily via displacement. This behavior results in more homogeneous mixing of Kr in ASW at 35 K compared to the dipole moment containing molecule CD3Cl. As a general outcome of our study, it is observed that mixing in ASW at low temperatures is more homogeneous when the guest atom/molecule is inert and does not possess a constant dipole moment.

Dielectric Constant and Dipole Moment Dependent Hysteresis in Suspended Bilayer Graphene Transistor

Manipulation of transport hysteresis on graphene-based field effect transistors and understanding electron transfer between graphene and organic solution are important for the development of graphene-based sensor device. Several papers regarding to the researches about hysteresis in graphene devices have been published, which are significant to graphene-based device[1 -3 ]. However, there are seldom papers focus on graphene with one-side organic solution which has different relative permittivity and various dipole moment constant. This means that graphene suspended in liquid which eliminates the effect of substrate and leaves graphene and liquid with pure structure. Therefore, we do further researches on the graphene-based device and explore the relationship between graphene and solution.In our research, the structure of the device is shown in Figure1, which includes two gold electrodes used for drain and source separately and the etched area which contains two larger rectangular area used for injecting liquid and one main trench with some pillars used for suspending graphene. When measuring each set of data, we did experiments in ambient environment and used the same suspended-graphene device to control the influence of the fabrication deviation, such as the contact resistance or the sheet resistance of bilayer graphene.Figure2(a) shows the SEM image of suspended graphene on the main trench and the significant differences can be seen between the parts where the graphene exists and does not exist, which proves the presence of suspended graphene. We do the same measurement the transport hysteresis in the device by using several solvent includes isopropanol (IPA), ethonal and dimethylacetamide (DMAC). Figure 2(b) shows the different hysteresis situations of three different solutions observed in this work. In the picture, the solid line illustrates the drain current change with the forward voltage which means voltage swept from -1V to 1V and the dotted line depicts the drain current alter with reverse scanning voltage called backward voltage. The value of hysteresis is defined as the difference between the voltage value corresponding to the lowest value of the forward curve and that of the backward curve，which is equal to the change between Dirac point.As shown in Figure 3(a), the difference between the hysteresis in the organic solution of various permittivity shows an almost curve correlation. Hysteresis value decreases as the dielectric constant drops, which can be explained by less charge trapping will cause smaller hysteresis. At the same time, the variety between the hysteresis of solvent with various dipole moment displays line with more obvious arc, which is shown in Figure3(b). These observations are interesting phenemonon which may related to the change on electrostatic environment of graphene[1] and the process of the competition between charge trapping effect and capacitive gating effect[2].In conclusion, we made several experiments to explore the relationship between graphene-based device and solvent with different electrical characteristics and found some interesting results of the difference between Dirac point regarding to permittivity and dipole moment. This characteristic may be used for judging the purity of organic solvents and other chemical or biological sensing application. Furthermore, it contribute to the fundamental development of relationship between graphene-based devices and different solvents.[1]Philipp Klar and Cinzia Casiraghi. Raman spectroscopy of graphene in different dielectric solvents[J].Phys. Status Solidi C,2010,7:2735-2738.[2]Wang, H.; Wu, Y.; Cong, C.; Shang, J.; Yu, T., Hysteresis of Electronic Transport in Graphene Transistors. ACS Nano 2010,4(12), 7221-8[3]Uysal, A.; Zhou, H.; Feng, G.; Lee, S. S.; Li, S.; Fenter, P.; Cummings, P. T.; Fulvio, P.F.; Dai, S.; McDonough, J. K.; Gogotsi, Y. Structural origins of potential dependent hysteresis at the electrified graphene/ionic liquid interface. J. Phys. Chem. C,2013,118, 569-574. Figure 1

Joint Effect of the Dipole–Dipole Interaction and Constant Dipole Moment on the Shape of the Field Pulse without an Envelope

An integrable model is proposed for a two-level medium with a constant dipole moment, which describes the evolution of electromagnetic field pulses without an envelope with account for the dipole–dipole interaction. In the nearest neighbor approximation, this interaction is taken into account in the form of quadratic dispersion. It is found that such a generalization of the reduced Maxwell–Bloch equations preserves the complete integrability. It is shown using the obtained exact soliton solutions as examples that the joint effect of quadratic dispersion and the constant dipole moment has a number of unique features and provides new opportunities for controlling the shape of field pulses. In particular, it is found that the shape and amplitude of a field pulse depend on the signs of the dipole–dipole interaction as well as on the sign of the constant dipole moment.

Generation of High-Frequency Radiation in the Conditions of Superradiance of Particles with a Constant Dipole Moment

A localized ensemble of identical particles with a constant dipole moment generates during superradiance a coherent pulse of low-frequency radiation, the pulse shape depending significantly on the number of particles in the ensemble. In particular, low-frequency radiation pulse is transformed from one-hump to two-hump shape in a narrow range of variation of ensemble parameters.

Theoretical and spectroscopic evidence on a new triphenyltin(IV) 3,5-dinitrosalicylhydroxamate complex: synthesis, structural characterization, and biological screening

The triphenyltin(IV) complex of composition [Ph3Sn(3,5-(NO2)2C6H2(OH)CONHO)] (1) has been synthesized by the reaction of Ph3SnCl with potassium 3,5-dinitrosalicylhydroxamate [3,5-(NO2)2C6H2(OH)CONHOK] and characterized by physicochemical studies, spectroscopic techniques (IR, 1H 13C, and 119Sn NMR), and mass spectrometry. The electrochemical behavior of ligand and 1 have been studied by cyclic voltammetry. The thermal behavior of 1 has been studied by thermogravimetric techniques (TGA, DTG, and DTA) and various kinetic parameters have been calculated. The optimized geometry of 1 was computed by the DFT method using B3LYP/631-G* set. The vibrational frequencies, 1H and 13C NMR spectra have been computed and compared with the experimental data. The global descriptors have been calculated. The various thermodynamic parameters, Gibbs free energy (G), enthalpy (H), entropy (S), bond energy (E), constant heat volume capacity (Cv), internal energy (U), and dipole moment (µ) have been calculated. The in vitro antimicrobial activity assay against pathogenic gram-(−) bacteria viz. Salmonella typhi, Escherichia coli; gram-(+) bacteria Bacillus cereus and Staphylococcus aureus; and fungi Fusarium sambucinum and Rhizoctona solani by MIC method; the in vitro cytotoxicity on human muscle rhabdomyosarcoma (RD) by MTT method and the antioxidant potential by DPPH free radical scavenging showed higher inhibitory effect of 1 than ligand.

Electrophysical properties of hydroxylated endohedral metallofullerene with gadolinium

The paper presents the results of experimental measurements of constitutive and electrophysical properties in hydroxylated endohedral metallofullerene with gadolinium sample. We extracted endohedral metallofullerene from carbon condensate, synthesized in high-frequency arc discharge plasma. Later hydroxyl groups were added. Via methods of infrared and x-ray photoelectronic spectroscopy, it was established that the molecules of hydroxylated endohedral metallofullerene have the Gd@C82Ox(OH)y, x + y=(40–42) composition. The method of measuring the electrical impedance in the frequency range from 100 Hz to 100 MHz shows that the resulting hydroxylated fullerene is an ion conductor. The measured frequency dependences of the dielectric permittivity and conductivity of hydroxylated fullerene are explained based on the assumption of an inhomogeneous distribution of electric charges in the material volume. Dielectric-hysteresis loops in the frequency range of 25 Hz–1 MHz and temperature range of 80–300 K, and volt-ampere characteristics were measured. The obtained results imply the appearance of residual polarization induced by the electric field in hydroxylated fullerene. However, the constant dipole moment is absent.

Electron Polarization Solitons in a Helical Molecule

The evolution of the spin of an electron moving along the axis of a long helical molecule under the action of an external field is investigated. The field is produced by the dipoles of individual molecules forming a complex molecular structure (e.g., a DNA molecule). The electron polarization dynamics associated with the spin–orbit interaction is described using an integrable generalization of the Manakov equations. The phase cross-modulation, self-modulation, and analogs of the Rashba and Dresselhaus Hamiltonians are taken into account in the model Hamiltonian. The corresponding apparatus based on the solution of the Riemann–Hilbert problem is used for obtaining soliton solutions. The resultant one- and two-soliton solutions demonstrate a number of new properties. It is shown that a local perturbation produces a selective effect on the soliton polarization and can be used for controlling the position of the electron spin using impurity molecules or quantum dots with a constant dipole moment. It is found that the spin–orbit interaction leads to a strong spatial modulation of the soliton shape. The collision of solitons leads to modulation transfer between solitons and a change in the modulation amplitude.

Exciton Dynamics in a Helical Molecular Aggregate

The formation of excitons in a helical molecular nanochain is considered. The model equations are derived with allowance for a spatial dispersion of the polarization of optical transitions treated in the approximation of nearest-neighbor interaction and constant dipole moment of molecules. Models of the medium are formulated, which determine the formation of polarization domains. Some examples are considered, which show that a helical medium admits the formation of stable localized structures (solitons) due to the curvature of the molecular chain. These features of the nanosystem can produce a critical influence on the luminescent properties of the chiral medium.

A simulation study of water property changes using geometrical alteration in SPC/E**Project supported by the National Natural Science Foundation of China (Grant Nos. 11635003, 11025524, and 11161130520), the National Basic Research Program of China (Grant No. 2010CB832903), and the European Commission’s 7th Framework Programme (Fp7-PEOPLE-2010-IRSES) (Grant Agreement Project No. 269131).

We present a systematic investigation of the impact of changing the geometry structure of the SPC/E water model by performing a series of molecular dynamic simulations at 1 bar (1 bar = 105 Pa) and 298.15 K. The geometric modification includes altering the H–O–H angle range from 90° to 115° and modifying the O–H length range from 0.90 Å to 1.10 Å in the SPC/E model. The former is achieved by keeping the dipole moment constant by modifying the O–H length, while in the latter only the O–H length is changed. With the larger bond length and angle, we find that the liquid shows a strong quadrupole interaction and high tetrahedral structure order parameter, resulting in the enhancement of the network structure of the liquid. When the bond length or angle is reduced, the hydrogen bond lifetime and self-diffusion constant decrease due to the weakening of the intermolecular interaction. We find that modifying the water molecular bond length leading to the variation of the intermolecular interaction strength is more intensive than changing the bond angle. Through calculating the average reduced density gradient and thermal fluctuation index, it is found that the scope of vdW interaction with neighbouring water molecules is inversely proportional to the change of the bond length and angle. The effect is mainly due to a significant change of the hydrogen bond network. To study the effect of water models as a solvent whose geometry has been modified, the solutions of ions in different solvent environments are examined by introducing NaCl. During the dissolving process, NaCl ions are ideally dissolved in SPC/E water and bond with natural water more easily than with other solvent models.

Stark effects in the ν_3 band of methane

Sub-Doppler resolution Stark-modulation spectra of 20 transitions in the ν3 band of methane have been recorded using a difference-frequency-generation source referenced to an optical frequency comb with a frequency uncertainty of a few kilohertz. First-order Stark shifts in the vibrational excited (v3=1) and ground states have been measured separately in the presence of an electric field up to 31 kV/cm. The observed spectra have been analyzed, taking into account the mixing of the vibration–rotation wave functions due to high-order vibration–rotation interactions. The permanent electric dipole moment constants induced by the vibration, rotation, and Coriolis-type terms in the v3=1 state, and those induced by rotation in the vibrational ground state, are determined as Pvib=−16.82(7) mDebye, Prot′=18.6(4) μDebye, PCor=10.4(17) μDebye, and Prot′′=24.47(12) μDebye.

Low-frequency emission in resonant processes

The paper shows analytically that any resonant interaction of quantum particles in media having no symmetry centre with a high-frequency exciting field produces low-frequency radiation. Media particles may not necessarily have a constant dipole moment. Conditions are identified when carrier frequency of low-frequency radiation coincides with nutational oscillations of resonant level populations and is readily controlled both by high-frequency resonant radiation intensity and by resonance detuning.

Non-adiabatic effects in near-adiabatic mixed-field orientation and alignment

We present a theoretical study of the impact of a pair of moderate electric fields tilted an angle with respect to one another on a molecule. As a prototype, we consider a molecule with large rotational constant (with corresponding small rotational period) and moderate dipole moment. Within rigid-rotor approximation, the time-dependent Schrodinger equation is solved using fourth-order Runge–Kutta method. We have analysed that lower rotational states are significantly influenced by variation in pulse durations, the tilt angle between the fields and also on the electric field strengths. We also suggest a control scheme of how the rotational dynamics, orientation and alignment of a molecule can be enhanced by a combination of near-adiabatic pulses in comparision to non-adiabatic or adiabatic pulses.

Control of dissipative solitons in a waveguide trap

A planar package of waveguides with heterogeneously implanted impurity resonance atoms is considered. The conditions of formation of dissipative solitons due to a competition of Kerr saturating nonlinearity and diffraction in the waveguide traps formed by impurity media are determined. It is shown that applying a constant electric field to an impurity resonance medium with a constant dipole moment makes it possible to control the propagation of solitons in Y-shaped waveguide traps.