Gold,silver, and palladium nanoparticle/nano-agglomerate generation,collection, and characterization

Generation, collection, and characterization of gold, silver, and palladium nanoparticles and nano-agglomerates (collectively “nanoparticles”) have been explored. The nanoparticles were generated with a spark aerosol generator (Palas GFG-1000). They were collected using a deposition cell under diffusion and thermophoresis. The shapes and sizes of the deposited particles were measured using transmission electron microscopy (TEM). TEM images showed that the particles were in the range of 8–100 nm in diameter, and their shapes varied from nearly spherical to highly non-spherical. Thermophoresis enhanced the deposition of nanoparticles (over the diffusive or the isothermal deposition) in all cases. Further, the size distributions of the nanoparticles generated in the gas phase (aerosol) were measured using a scanning mobility particle sizer (SMPS 3080, TSI) spectrometer. The SMPS results show that an increase in the spark frequency of the generator shifted the size distributions of the nanoparticles to larger diameters, and the total particle mass production rate increased linearly with increase in the spark frequency. The computational fluid dynamics code Fluent (Ansys) was used to model the flow in the deposition cell, and the computed results conform to the observations.     

Einstein,Podolsky, Rosen,and Shannon

The Einstein–Podolsky–Rosen paradox (1935) is reexamined in the light of Shannons information theory (1984). The EPR argument did not take into account that the observers information was localized, like any other physical object.Dedicated to the memory of James T. Cushing     

Spin, gravity, and inertia

The gravitational effects in the relativistic quantum mechanics are investigated. The exact Foldy-Wouthuysen transformation is constructed for the Dirac particle coupled to the static spacetime metric. As a direct application, we analyze the nonrelativistic limit of the theory. The new term describing the specific spin (gravitational moment) interaction effect is recovered in the Hamiltonian. The comparison of the true gravitational coupling with the purely inertial case demonstrates that the spin relativistic effects do not violate the equivalence principle for the Dirac fermions.     

Bits,time, carriers,and matter

The formal structure of quantum information theory is based on the well-founded concepts and postulates of quantum mechanics. In the present contribution, I am inverting the usual approach presented in textbooks by beginning with the use of bit states as basic and fundamental units of information and establish a dynamical map for them. The condition of reversibility, imposed on an ordered sequence of actions operating on a bit state, introduces, by necessity, the unitarity property of actions. I also verify that the uniformity of time, as a parameter for ordering events, is due to the admission of a composition law for the actions. In the limit of infinitesimal intervals between actions, a reversible and linear equation arises for the dynamical changes in time of a qubit (superposition of bit states). The admission that a bit of information is stored or carried by a massive particle necessarily leads to the Schrödinger–Pauli equation (SPE); the bit is associated to a spin 1/2. Within this approach, I verify that the particle dynamical equation becomes “enslaved” by the spin dynamics. In other words, the bit (or spin) precedes in status the particle dynamical evolution, being at the root of the quantum character of the standard Schr¨odinger equation, even when spin and spatial degrees of freedom are uncoupled.     

Compensation,nonlinearity, and geometry

A new approach to the theory of compensating fields is given. The theory is extended to the case of an arbitrary Lie group and leads to a nonlinear field theory, describing the interaction of physical fields and the generation by this interaction of a non-Euclidean space-time geometry, generalizing the well-known result of the Einstein theory on the connection between geometry and matter. The theory is applied to a number of groups.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 128–134, December, 1974.The author is grateful to Professor D. D. Ivanenko, who has made such significant contributions to the development of the theory of compensation and its nonlinear generalizations and to the treatment of gravitation as a gauge field. The author also wishes to thank B. N. Frolov and V. N. Ponomarev for valuable discussions.     

Stress, strain, and NMR

Experimental and ab initio results that demonstrate the effect of stress on the nuclear magnetic resonance spectra of materials are shown. The design of a cell that generates uniaxial compressive stress is presented, and results on gallium phosphide and lead nitrate single crystals that illustrate the observable results of the stress are shown. Tensors that relate stress and strain to changes in the chemical shielding tensors and the electric field gradient tensors are defined formally. The elements of these tensors are then computed by a density functional theory approach that makes use of planewaves and pseudopotentials. The experimental results are interpreted with the aid of the calculations. Extensions to spinning samples and to the interpretation of optical phenomena in materials are discussed.     

Mesomorphic, dielectric, and optical properties of fluorosubstituted biphenyls, terphenyls, and quaterphenyls

Compounds with moderate and large negative dielectric anisotropy (Δɛ) are very attractive liquid crystal (LC) for vertical alignment mode (VA). Materials with such properties can be achieved by lateral substitution of a polar group into a mesogenic molecule. We synthesized some new LC materials with a negative value of Δɛ, a moderately high birefringence (Δn), and a low viscosity. The mesomorphic and physical behaviour of the novel biphenyls, terphenyls and quaterphenyls fluorosubstituted in the rigid core and also with fluorinated alkyl and alkoxy chains are investigated. The prepared series of four LC compounds are promising for new LC mixtures for various applications. Examples of nematic mixtures with Δɛ∼−3.25 will be presented.     

Electron, positron, and photon wakefield acceleration: trapping, wake overtaking, and ponderomotive acceleration

The electron, positron, and photon acceleration in the first cycle of a laser-driven wakefield is investigated. Separatrices between different types of the particle motion (trapped, reflected by the wakefield and ponderomotive potential, and transient) are demonstrated. The ponderomotive acceleration of electrons can be largely compensated by the wakefield action, in contrast to positrons and positively charged mesons. The electron bunch energy spectrum is analyzed. The maximum upshift of an electromagnetic wave frequency during reflection from the wakefield is obtained.     

Density functional theory study of structural,electronic,and thermal properties of Pt,Pd, Rh,Ir, Os and PtPdX(X= Ir,Os, and Rh) alloys

The structural, electronic, mechanical, and thermal properties of Pt, Pd, Rh, Ir, Os metals and their alloys Pt Pd X(X= Ir, Os and Rh) are studied systematically using ab initio density functional theory. The groundstate properties such as lattice constant and bulk modulus are calculated to find the equilibrium atomic position for stable alloys. The electronic band structure and density of states are calculated to study the electronic behavior of metals on making their alloys. The electronic properties substantiate the metallic behavior for all studied materials. The firstprinciples density functional perturbation theory as implemented in quasi-harmonic approximation is used for the calculations of thermal properties.We have calculated the thermal properties such as the Debye temperature, vibrational energy, entropy and constant-volume specific heat. The calculated properties are compared with the previously reported experimental and theoretical data for metals and are found to be in good agreement. Calculated results for alloys could not be compared because there is no data available in the literature with such alloy composition.     

Antipursuit,metaxydiosis, and carcinogenesis

The possibility is considered of modelling the biological processes of morphogenesis and carcinogenesis, not aetiologically but geometrically, by two kinematic processes: pursuit and antipursuit. Like morphogenesis, pursuit is stable and even self-stabilizing, while the inverse antipursuit, like carcinogenesis, may be explosively unstable. The various stability and instability features are exhibited mainly graphically. Finally, a single compound process is proposed which embraces both pursuit and antipursuit.     

Results in One, Two, and Three Dimensions, for Delta Functions, Square Wells, and Delta Shells, Respectively

 I will outline three-particle calculations, and results, in one dimension [1–4] with delta-function interactions, in two dimensions [5–11] for square wells and in three dimensions [12] with delta shells. The presentation will be that of my own work, obtained together with colleagues. The initial approach is that of expansions of the wave function in terms of hyperspherical adiabatic functions, usually deduced from hyperspherical harmonics. Received October 29, 2001; accepted for publication November 23, 2001     

Black swans,power laws,and dragon-kings: Earthquakes,volcanic eruptions,landslides, wildfires,floods, and SOC models

Extreme events that change global society have been characterized as black swans. The frequency-size distributions of many natural phenomena are often well approximated by power-law (fractal) distributions. An important question is whether the probability of extreme events can be estimated by extrapolating the power-law distributions. Events that exceed these extrapolations have been characterized as dragon-kings. In this paper we consider extreme events for earthquakes, volcanic eruptions, wildfires, landslides and floods. We also consider the extreme event behavior of three models that exhibit self-organized criticality (SOC): the slider-block, forest-fire, and sand-pile models. Since extrapolations using power-laws are widely used in probabilistic hazard assessment, the occurrence of dragon-king events have important practical implications.     

Structural, energetic, and electronic properties of Sin, Gen, and SinGen clusters

Results of a theoretical study of the properties of Si_n, Ge_n, and Si_nGe_n clusters are presented. An approximate density-functional method in combination with genetic algorithms have been used in an unbiased determination of the structures of the lowest total energy. The resulting structural, energetic, and electronic properties are analysed and compared with each other for the different systems.     

Phase sensitive,all-optical and self-integrated multi-logic AND,OR, XOR,and NOT gates

The design and simulation of all-optical and self-integrated primary logical AND, OR, XOR and NOT gates based on phase sensitivity of spatial optical solitons have been reported. By tuning the phase of incident solitons into a bulky nonlinear Kerr medium and interaction between the phase tuned solitons, the self-integrated logical gates are achieved simultaneously in a 50 μm long distance by one setup. These are the advantages in the application and design of integrated circuits. In addition, the proposed logical gates can be cascaded and the logical AND and XOR gates can simultaneously have two outputs. The simplicity of constructing, simultaneous functions with one setup, the possibility of integrating, high sensitivity and fabrication ease are the advantages of the proposed logical gates and may be a good candidate for the future of integrated photonic computational circuits.     

Elements,devices, and methods for fractal communication technology,electronics, and nanotechnology

The numerous results obtained in radio physics using fractal theory, fractional dimension, and fractional operators have been briefly classified taking into account the scaling effects of real radio signals and electromagnetic fields. A universal modeling environment based on a multilayer virtual generalized distributed RLCG element and the method of generalized finite distributed elements for analysis and synthesis of models of fractional objects and processes that possess fractional power dependence of the input impedance on frequency have been proposed. Examples of synthesis of one- and two-dimensional models are given. It is shown that nonlinear, parametrical, and other properties of modeled objects can be taken into consideration by means of the vectors of electrophysical parameters of layers and design factors.     

Symmetry,crystallography, and art

Crystallography, a scientific discipline about the properties and structure of crystals, and the arts seem to be two different areas of human endeavor. There are, indeed, many differences between them – however, there are also similarities. The concept of symmetry can be used as a bridge to recognize such similarities. Symmetry is everywhere, in the hard sciences, in the arts, in nature, and in our everyday life; therefore it seems to be a natural choice for connecting the seemingly disparate fields of crystallography and the arts. In the following, first we look at science and the arts through one of the simplest symmetries, reflection. This is followed by considerations of chirality, which is related to reflection in a special way. Further, space groups will be discussed, the one-, two-, and three-dimensional space groups with examples from both the sciences and the arts. The symmetries of crystal structures belong to the three-dimensional space groups. PACS 01.30.Bb; 01.65.+g; 01.70.+w; 01.75.+m     

Gravitation,torsion, and electromagnetism

A term bilinear in the derivative of the torsion is added to the Lagrangian of general relativity to produce torsion that propagates. Using standard variational techniques, field equations are derived with the torsion being interpreted as the electromagnetic potential and the antisymmetric part of the Ricci tensor as the electromagnetic field tensor. The equation of motion is derived from the field equations, and the results are compared to the Einstein-Maxwell formulation.     

Ab initio electronic, dynamic, and thermodynamic properties of isotopic lithium hydrides (LiH, LiD, LiT, LiH, LiD, and LiT)

The structural, dielectric, lattice-dynamical, and thermodynamical properties of isotopic lithium hydrides (⁶LiH, ⁶LiD, ⁶LiT, ⁷LiH, ⁷LiD, and ⁷LiT) were investigated within density-functional theory. The atomic structure was fully relaxed and the structural parameters were found to differ by less than 2% from the experimental data. The associated electronic band structure and density of states were also presented. A linear-response approach to the density-functional perturbation theory was employed to work out the Born effective charges, dielectric tensors and phonon frequencies, and thermodynamic properties. The compounds with the heavier Li isotope or H isotope have the lower phonon frequencies; ⁶LiT is more stable than ⁷LiT, ⁶LiD, ⁷LiD, ⁶LiH, and ⁷LiH in the temperature range 0-2700 K. These properties of LiT were predicted for the first time. The results were discussed in terms of the isotope effects on phonon dispersion curves and thermodynamic properties.     

Peirce, Clifford, and Dirac

There is a clear line of progression from the logic of relations of Charles Sanders Peirce through the algebras of William Kingdon Clifford. Further, it has been shown how one can obtain the nonrelativistic quantum theory of spin one-half particles from Peirce logic. Continuing the hypothetical history, it is demonstrated here that the relativistic Dirac theory can also be related to Peirce logic. The most natural way to accomplish this is to represent the Dirac wave functions themselves as Clifford numbers rather than as spinors. The wave functions can thus appear as 4× 4 matrices. All quantities in this quantum theory can actually be expressed in terms of the Clifford basis, independent of a specific matrix representation.     

Bonding in Cu,Ag, and Au clusters: relativistic effects,trends, and surprises

Electronic structure and bonding in anionic coinage metal clusters are investigated via density-functional calculations, focusing on an extensive set of isomers of Cu(-)(7), Ag(-)(7), and Au(-)(7). While the ground states of Cu(-)(7) and Ag(-)(7) are three dimensional (3D), that of Au(-)(7) is planar, separated from the optimal 3D isomer by 0.5 eV. The simulated thermally weighted photoabsorption spectrum of Au(-)(7) is dominated by planar structures, and it agrees well with the measured one. The propensity of Au(-)(N) clusters to favor planar structures (with N as large as 13) is correlated with strong hybridization of the atomic 5d and 6s orbitals due to relativistic effects.