Activation energy on three-dimensional Casson nanofluid motion via stretching sheet: Implementation of Buongiorno’s model

In this work, the statistical (“Numerical”) modelling of activation energy and chemical reaction on non-Newtonian liquid motion via stretching sheet (SS) were performed, analysed statistically, employing the shooting technique. The convective boundary conditions are considered on Casson liquid (“non-Newtonian”) motion with couple stress SS. The behaviour of thermophoresis diffusion and Brownian motion via a special effect of non-linear thermal radiation are assuming in temperature equation for liquid motion. This analysis highly governing nonlinear system of D. Es of velocity, temperature, concentration and activation are simulated via iterative scheme encoded with MATLAB programming language. The geometric model is described bvp 4th order of R-K-F (“Range-Kutta-Fehlberg”) scheme. We found that, 35% of heat transfer rate produces in motion of couple stress Casson nanofluid and the activation energy released 28% of mass transfer rate at stretching surface. A comparative result of linear and nonlinear SS presented via various dimensionless parameters on graphs and tables.     

Heat capacities of liquids linear aliphatic polyoxides

Heat capacities at constant pressure of liquid polyoxymethylene (430-540 K) and polyoxyethylene (330-430 K) have been measured by scanning calorimetry. These new data are discussed together with the heat capacity of polyethylene and other linear, aliphatic polyoxides to arrive at a wide-range addition scheme for heat capacities. Values of absolute entropy, enthalpy, and Gibbs free energy are estimated. The new data are offered as “Recommended Data 1984” in our ATHAS Data Bank.     

Model calculation of weak and medium strong linear hydrogen bonded systems

The model hamiltonian with two coupling constants between the low and high frequency vibrations of a linear AH?B system is studied. The results show that the wave functions and energy levels of this hamiltonian obtained by exact diagonalisation can be adequately approximated by the wave functions and energy levels of a harmonic “effective hamiltonian”. The experimental spectrum of (CH₃)O?HCl in the stretching region was reconstituted by means of this model.     

Effect of Energy Transfer on UV Spectra of “H-shaped” Azobenzene Derivatives

A series of “H-shaped” organic dimers (azobenzene derivatives) exhibit linear absorption red shift compared with their corresponding monomers experimentally. Dipolar interaction model is not appropriate for the azobenzene derivatives due to the small distance between two “D-π-A” chains. Energy transfer model is suggested for explanation of the absorption red shift. Two necessary conditions for energy transfer were verified. In addition, bi-exponential florescence-delay behavior of the dimer as well as Bella's quantum chemistry calculation shows evidence of energy transfer.     

Construction of triblock copolymer-gold nanorod composites for fluorescence resonance energy transfer via pH-sensitive allosteric

To explore the effects of microenvironmental adjustments on fluorescence, a pH-sensitive nano-composite system based on fluorescence resonance energy transfer (FRET) was constructed. The model system included a modified triblock copolymer (polyhistidine-b-polyethylene glycol-b-polycaprolactone) and gold nanoparticles. A near-infrared dye was used as the donor, and spectrally matched gold nanorods, attached after C-terminus modification with α-lipoic acid, were used as the receptor to realize control of the FRET effect over the fluorescence intensity for two polymer configurational changes (i.e., “folded” and “stretched” states) in response to pH. After synthesis and characterization, we investigated the self-assembly behavior of the system. Analysis by quartz crystal microbalance revealed the pH sensitivity of the polymer, which exhibited “folding” and “stretching” states with changes in pH, providing a structural basis for the FRET effect. Fluorescence spectrophotometry investigations also revealed the regulatory impact of the assembled system on fluorescence.     

Complex heat capacity measurements by TMDSC Part 1. Influence of non-linear thermal response

To treat data from temperature modulated differential scanning calorimetry (TMDSC) in terms of complex or reversing heat capacity one should know heat transfer and apparatus influences on experimental results. On the other hand one should pay attention that the response is linear because this is a prerequisite for data evaluation. The reason for non-linear thermal response is discussed and its influence on complex heat capacity determination is shown. The criterion for linear response is proposed. This allows to choose correct experimental conditions for any complex heat capacity measurements. In the case when these conditions cannot be fulfilled because of experimental restrictions one can estimate the influence of non-linear response on measured value of complex or reversing heat capacity.     

Calorimetric studies of poly(ethylene terephthalate) stretching over a wide temperature range

Heat effects and structural transformations in amorphous crystallizable poly(ethylene terephthalate) (PET) during uniaxial stretching accompanied by neck formation, have been investigated by calorimetric and x-ray methods over a wide range of temperatures and deformation rates. At small deformation (not exceeding 1–2%) and at temperatures below the glass transition temperature of the polymer, PET behaves as an elastic body. Upon stretching at a constant rate, constant heat power is absorbed, heat effects during loading and unloading coincide completely, and no hysteresis is observed. At large deformations (of the order of 50%), cold drawing develops in this temperature range. The internal energy change in cold drawing is zero within experimental error. A periodic heat release during the self-oscillation regime of drawing PET corresponds to periodic changes in stress, in the rate of the neck formation, and in the appearance of the sample. The temperature limits of the region where crystallization resulting from an uniaxial drawing of the polymer is possible, have been determined, and the heat effect of this phase transition has been measured. Orientation crystallization develops only from 70 to 94°C. These limits are insensitive to changes in deformation rate within one decimal order. The structure of PET in this temperature range has been investigated. The heat of phase transition of orientation crystallization of PET has been determined from the relationship between the measured values of the internal energy change during this process and the limiting degree of crystallinity for the stretched samples. This heat proves to be 5.5 ± 0.1 cal/g.     

Estimations homogénéisées pour les composites hyperélastiques et applications aux élastomères renforcés

This Note is concerned with the development of variational estimates for the effective stored-energy function of hyperelastic composites undergoing finite deformations. It makes use of a suitable generalization of the “second-order procedure” of Ponte Castañeda, the key idea being the introduction of an optimally chosen “linear thermoelastic comparison composite”, which can then be used to convert available homogenization estimates for linear systems directly into new estimates for hyperelastic composites. The resulting estimates are known to be exact to second order in the contrast. An application is given for particle-reinforced rubbers.     

Construction of triblock copolymer-gold nanorod composites for fluorescence resonance energy transfer via pH-sensitive allosteric

To explore the effects of microenvironmental adjustments on fluorescence, a pH-sensitive nanocomposite system based on fluorescence resonance energy transfer (FRET) was constructed. The model system included a modified triblock copolymer (polyhistidine-b-polyethylene glycol-b-polycaprolactone) and gold nanoparticles. A near-infrared dye was used as the donor, and spectrally matched gold nanorods, attached after C-terminus modification with α-lipoic acid, were used as the receptor to realize control of the FRET effect over the fluorescence intensity for two polymer configurational changes (i.e., “folded” and “stretched” states) in response to pH. After synthesis and characterization, we investigated the self-assembly behavior of the system. Analysis by quartz crystal microbalance revealed the pH sensitivity of the polymer, which exhibited “folding” and “stretching” states with changes in pH, providing a structural basis for the FRET effect. Fluorescence spectrophotometry investigations also revealed the regulatory impact of the assembled system on fluorescence.     

Hyperthermal energy distribution functions of the adspecies in recombinative adsorption at catalytic surfaces and their relevance to ‘hot atom’ reactions

We report on the modeling of the energy distribution functions of the adspecies in diatom formation at catalytic surfaces under steady state conditions. To this end master equations are employed, in the case of either continuous or discrete set of adatom energy levels in the adsorption potential well, and the impact of the distribution function on reaction rate investigated. The transition from thermal to hyperthermal reaction rates has been studied as a function of rate coefficients for recombination and energy dissipation processes. Experimental data available from the literature, have been analysed in the framework of the theoretical model. It is shown that hyperthermal energy distribution functions entail a “hot atom” reaction mechanism.     

The relative sign of through-bond and through-space interactions; “sigma assistance” of cyclization and intramolecular hydrogen transfer

A perturbational frontier MO model indicates that the relative sign of the through-bond and through-space interaction in nonconjugated bifunctional molecules alternates with the number (N) of intervening sigma bonds. The qualitative predictions from the FMO model are in full accord with quantitative computational and experimental literature data, the latter being mainly available for N<4. It is suggested that alternation of the relative sign of through-bond and through-space interactions with N effect—for which the name “sigma assistance” is proposed—may account for the preference of radical cyclizations to yield odd membered instead of even membered rings and for the preference of hydrogen transfer to occur via an even membered transition state.     

Anharmonic effects in ammonium nitrate and hydroxylammonium nitrate clusters

The covalent and ionic clusters of ammonium nitrate and hydroxyl ammonium nitrate are characterized using density functional theory and second-order vibrational perturbation theory. The most stable structures are covalent acid-base pairs for the monomers and ionic acid-base pairs for the dimers. The hydrogen-bonding distances are greater in the ionic dimers than in the covalent monomers, and the stretching frequencies are significantly different in the covalent and ionic clusters. The anharmonicity of the potential energy surfaces is found to influence the geometries, frequencies, and nuclear magnetic shielding constants for these systems. The inclusion of anharmonic effects significantly decreases many of the calculated vibrational frequencies in these clusters and improves the agreement of the calculated frequencies with the experimental data available for the isolated neutral species. The calculations of nuclear magnetic shielding constants for all nuclei in these clusters illustrate that quantitatively accurate predictions of nuclear magnetic shieldings for comparison to experimental data require the inclusion of anharmonic effects. These calculations of geometries, frequencies, and shielding constants provide insight into the significance of anharmonic effects in ionic materials and provide data that will be useful for the parametrization of molecular mechanical force fields for ionic liquids. Anharmonic effects will be particularly important for the study of proton transfer reactions in ionic materials.     

Effects of double substitution on the thermodynamic stabilities of nitrogen radicals

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On vibrational bonding of IHI

The vibrational bond of IHI is described in analogy to the covalent bond of H₂⁺ by a Born—Oppenheimer-type separation of light (“hydrogenic” ≡ “electronic”) and heavy (“iodines” ≡ “protons”) particle degrees of freedom. Competing potential energy decreases and hydrogen zero-point energy increases (for the IHI antisymmetric stretching and bending modes) yield a minimum in the iodine symmetric stretching mode's potential energy which supports one bound vibrational IHI state.     

Mechanical structures in polymer melts. II. Roles of entanglements in viscosity and elastic turbulence

Current theories of polymer flow processes often sacrifice realistic molecular models for simplicity of their mathematical equations. An analysis of what might happen to molecules of more realistic sizes and shapes under shear flow, shows the importance of the rapid Brownian motion of chain segments, the elastic deformations of polymer random coils, and the dissipation of this elastic random coil energy by the relatively slow slippage of the chains past each other at a few entanglements where steric hindrance causes long relaxation times. This makes the energy loss depend on the time at each local deformation, and not on the overall shear rate. At high shear rates this model leads to “cluster flow” and low loss cyclic deformations, rather than the high loss processes of steady-state shear. This model gives reasonable qualitative explanations for many anomalous flow properties, and it has predicted new effects that have since been observed.     

Radioactive contaminants in the subsurface: the influence of complexing ligands on trace metal speciation

Equilibrium thermodynamics is one of the pillars which support safety analyses of repositories for radioactive waste. The research summarized in this review deals with approaches to resolve the problems related to thermodynamic equilibrium constants and solubility of solid phases in the field of radioactive waste management. The results have been obtained at the Paul Scherrer Institut between 1995 and 2005 and comprise the scientific basis of the author’s habilitation thesis in the field of nuclear environmental chemistry. The topics are grouped according to three different levels of problem solving strategies: (1) Critical and comprehensive reviews of the available literature, which are necessary in order to establish a reliable chemical thermodynamic database that fulfils the requirements for rigorous modeling of the behavior of the actinides and fission products in the environment. (2) In many case studies involving inorganic and simple organic ligands a serious lack of reliable thermodynamic data is encountered. There, a new modeling approach to estimate the effects of these missing data was applied. This so called “backdoor approach” begins with the question, “What total concentration of a ligand is necessary to significantly influence the speciation, and hence the solubility, of a given trace metal?” (3) In the field of natural organics, mainly humic and fulvic acids, we face an ill-defined problem concerning the molecular structure of the ligands. There, a pragmatic approach for performance assessment purposes was applied, the “conservative roof” approach, which does not aim to accurately model all experimental data, but allows estimates of maximum effects on metal complexation by humic substances to be calculated.     

Semiclassical calculation of energy transfer in polyatomic molecules. VII. Intra- and inter-molecular energy transfer in N2 + CO2

Rate constants for inter- and intra-molecular energy transfer in the N₂ + CO₂ system are obtained in the temperature range 200–2000 K with three different sets of potential short-range parameters. Comparison with available experimental data is carried out. The analytical solution to the “inversion problem” for the M-quantum case is also presented.