Miracle-dz/UniFAR-FTUs huggingface dataset:
Facile Synthesis of Cu2O Nanocrystals with Systematic Shape Evolution from Cubic to Octahedral Structures

We report a facile method for the synthesis of cuprous oxide nanocrystals with systematic shape evolution. Monodisperse truncated cubic, cuboctahedral, truncated octahedral, and octahedral nanocrystals can be synthesized directly in an aqueous solution of CuCl2, sodium dodecyl sulfate (SDS) surfactant, hydroxylamine (NH2OH·HCl) reductant, and NaOH by simply varying the volume of hydroxylamine added to the reaction mixture. SDS surfactant was found to be necessary for a precise control of the nanocrystal morphology. Adjustment of the volume of NaOH added provides a means to vary the particle size. In the case of octahedral nanocrystals, particles with sizes of 160−460 nm can be prepared. By examining the intermediate products formed, which resemble the final nanocrystal structures, a growth mechanism is proposed. Optical characterization of these Cu2O nanocrystals showed band gap absorption at 470−490 nm and strong light scattering bands extending from the visible to the near-infrared light region. All fou.
Pulsed EPR Study of Spin-Coupled Radical Pairs in Photosynthetic Reaction Centers: Measurement of the Distance Between and in Photosystem I and between and in Bacterial Reaction Centers

The spin-polarized radical pairs P{sub 865}{sup {center_dot}+}Q{sub A}{sup {center_dot}-} in protonated and deuterated Zn-substituted reaction centers from two different mutants of the photosynthetic bacteria Rhodobacter sphaeroides and P{sub 700}{sup {center_dot}+}A{sub 1}{sup {center_dot}-} in plant photosystem I from Synechococcus elongatus are investigated by pulsed EPR spectroscopy. Spin-polarized radical pairs give rise to a characteristic out-of-phase electron spin echo. This echo shows a deep envelope modulation with a frequency governed by the spin-spin interaction. The known distance dependence of the magnetic dipolar interaction allows the determination of the distance between the cofactors carrying the unpaired electron spins. For the bacterial reaction centers this distance is known for the electronic ground state from crystal structures and is compared here with the distance of the radical pair spins, i.e. the charge-separated state. In photosystem I the location of the acceptor A{sub 1} is not known yet. A distance of 25.4 {+-} 0.3 angstrom between P{sub 700}{sup {center_dot}+} and A{sub 1}{sup {center_dot}-} is obtained here and gives new structural information on photosystem I. 42 refs., 6 figs.
Subpicosecond carrier lifetimes in radiation‐damaged GaAs

We investigate the dependence of carrier lifetimes in radiation‐damaged, GaAs on proton implantation dose by means of time‐resolved reflectivity and photoconductivity experiments with subpicosecond resolution. The carrier lifetimes decrease with increasing implantation dose at low implantation levels whereas beyond the ‘‘amorphization dose’’ a saturation at 0.5 ps can be observed due to a saturation of the defect density.
Degradation of an Azo Dye with Homogeneous and Heterogeneous Catalysts by Sonophotolysis

This study illustrates the degradation of an azo dye, Reactive Yellow 81 (RY81), by the combined irradiation of UV-C and ultrasound in the presence of homogeneous (Fe2+) and heterogeneous (TiO2, ZnO) catalysts. The efficiency of homogeneous and heterogeneous oxidation systems was evaluated in regard of the decolorization and mineralization of RY81. Decolorization followed pseudo-first-order kinetics with homogeneous and heterogeneous catalysts. Complete color removal was accomplished by homogeneous sonocatalytic and sonophotocatalytic oxidation processes with apparent rate constants of 0.96 × 10−3 and 46.77 × 10−3 s−1, respectively, in the presence of Fe2+. However, partial color removal was obtained by heterogeneous sonocatalytic, photocatalytic, and sonophotocatalytic oxidation processes with apparent rate constants of 2.32 × 10−3, 3.60 × 10−3, and 3.67 × 10−3 s−1, respectively, in the presence of ZnO. TiO2 had the worst catalytic effect of all of the oxidation processes. The addition of hydrogen peroxide increased the rate constants of the heterogeneous oxidation processes and decreased the rate constants of the homogeneous oxidation processes. RY81 mineralization was 62.8% for the US/UV/Fe2+ homogeneous oxidation process, which was the best oxidation process, whereas it was 43.5% for the US/UV/ZnO/H2O2 heterogeneous oxidation process within 2 h reaction time.
Local Structure of the Infrared Bismuth Luminescent Center in Bismuth‐Doped Silica Glass

Several instrumental analyses, such as spectroscopic properties, luminescent intensity, nuclear magnetic resonance, X-ray diffraction, electron spin resonance, X-ray photoelectron spectroscopy, and extended X-ray absorption fine structure, have been performed on a Bi2O3–Al2O3–SiO2 glass system. After the roles and the structure of the Al ions and the valence state of the luminescent Bi ions were experimentally examined, it was recognized that aluminum ions with a sixfold corundum structure behave like a “generator” of the luminescent center and that the valence state of Bi5+ is suitable for the distinctive Bi luminescent center. Because a certain image of the local structure of the Bi luminescent center is built by instrumental analyses without discrepancies, the distinctive bismuth luminescent center model reveals that the sixfold coordination state of Bi5+ is combined with the sixfold corundum structure of Al3+ through an oxygen ion.
Kinetic Analyses of Solid‐State Reactions with a Particle‐Size Distribution

Kinetic analyses for the solid-state reactions of reactant particles in an assemblage with a particle-size distribution (PSD) have been reexamined for the reactions that proceed by the advance of the reaction interfaces inward toward the center of the individual reactant particles. The experimental kinetic curves for a particle assemblage are influenced by the existing PSD. It has been demonstrated that, even if PSD exists, a reliable activation energy E can be obtained from such overall kinetic curves by the empirical isothermal analysis without accounting for the PSD. The isoconversion methods, which enable us to determine the E value from the data points at a given fractional reaction of a series of experimental kinetic curves, are methodologically independent of the PSD. It is neccessary to incorporate the PSD into the kinetic equation to select an appropriate kinetic model and to evaluate the preexponential factor A. The method of kinetic calculation accounting for the PSD can be generalized, for the kinetic data under any thermal profiles, by extrapolating all the analytical conditions to infinite temperature. For the reaction characterized by the well-defined PSD and kinetic model function, the meaningful A value is obtained by the kinetic analysis at infinite temperature. Although the ability to discriminate the contracting geometry of the reaction interface in a single particle from the overall kinetic curve decreases with increasing PSD, the rate-controlling steps for the advance of the reaction interface, i.e., chemical reaction controlled or diffusion controlled, can be distinguised from each other even for the reactions with a fairly large PSD.
Errata: The Intrinsic Viscosities and Diffusion Constants of Flexible Macromolecules in Solution

A theory of the intrinsic viscosities and translational diffusion constants of flexible macromolecules is developed on the basis of the random coil model with hindered internal rotation. Proper account is taken of the hydrodynamic interaction of the monomer units of the molecule and of inhibited flow through the chain. The theory leads to results qualitatively similar to those obtained by Debye on the basis of a molecular model consisting of a sphere containing a uniform distribution of resisting points. However, significant quantitative differences between the two theories are found.
Beyond the Carbon Economy: The Energy Law in Transition

Review of: Beyond the Carbon Economy: The Energy Law in Transition, edited by Donald N. Zillman, Catherine Redgwell, Yinka O. Omorogbe and Lila K. Barrera-Hernandaz, Oxford University Press, Oxford, xv, 562 pp. ISBN 13: 9780199532698.
Hierarchical Pore Structures Fabricated by Electron Irradiation of Silicone Grease and their Applications to Superhydrophobic and Superhydrophilic Films

Unique hierarchical pore structures were fabricated by simply irradiating an electron beam onto silicone grease films. The hierarchical pore structures consisted of micrometer-sized pores and macroporous walls. Due to the high surface roughness, the hierarchical pore structures exhibited both superhydrophobicity with a water contact angle (CA) of 170° and superhydrophilicity with an extremely low water CA of 3° after the chemical treatment of the surfaces. In addition to the hierarchical pore structures, sponge-like pore structures were also fabricated by the electron irradiation of silicone grease films.
Optimization of the Deposition Parameters of DLC Coatings with the IC-PECVD Method

Amorphous carbon film, also known as diamond-like carbon (DLC) film, is a promising material for tribological application. It is noted that properties relevant to tribological application change significantly depending on the method of preparation of these films. These properties are also altered by the composition of the films. In view of this, the purpose of the present study was to determine the optimal values of selected deposition parameters of hydrogenated DLC films on high-speed steel tool substrates with the inductively coupled plasma enhanced chemical vapor deposition (IC-PECVD) method. To optimize the deposition parameters for hydrogenated DLC films, Taguchi's method was used. Deposition parameters (bias voltage, bias frequency, deposition pressure, and gas composition) were optimized with consideration to hardness of the film. Based on the experimental results, the optimal parameter setting are −50 V, 500 Hz, 4 µbar, and 90:10 for achieving maximum value of hardness. It was found that bias voltage has greater influence on hardness. At the optimum conditions, the conformance run resulted in a hardness value of 1580 KHN. Atomic force microscopy images showed that the DLC films are smooth with an average roughness (Ra) of 1.24 nm on silicon substrate.
ATOMIC ABSORPTION SPECTROMETRIC DETERMINATION OF TRACE AMOUNTS OF COBALT AFTER SEPARATION AND PRECONCENTRATION WITH USE OF 5-Br-PADAP

ABSTRACT Cobalt is quantitatively retained on 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP)-ammonium tetraphenylborate with microcrystalline naphthalene or by a column method in the pH range 3.5–9.5 from large volumes of aqueous solutions of various samples. After filtration, each solid mass consisting of the cobalt complex and naphthalene was dissolved with 5 mL of dimethylformamide and the metal was determined by flame atomic absorption spectrometry. Cobalt complex can alternatively be quantitatively adsorbed on ammonium tetraphenylborate–naphthalene adsorbent packed in a column and determined similarly. In this case, 0.15 µg of cobalt can be concentrated in a column from 600 mL of aqueous sample, where its concentration is as low as 0.25 ppb. Eight replicate determinations of 0.7 ppm of cobalt gave a mean absorbance of 0.085 with a relative standard deviation of 1.6%. The sensitivity for 1% absorption was 36 ppb. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for the trace determination of cobalt in various standard samples.
Design and test of a heat pipe for geothermal applications

Heat pipes are typically used in the semiconductor industry. This means that the scale of these heat pipes is typically in the order of centimeters. Zijm suggests that heat pipes could be used for geothermal applications, but literature is lacking. To further investigate the geothermal application of heat pipes, a large scale heat pipe is built. This thesis gives an insight in the typical design challenges that one faces when constructing a heat pipe of this scale. The heat pipe that is constructed can support a heat flow of 10 kW. The heat pipe is constructed from mainly 54 millimeter copper and glass pipes. The evaporator section is 1.5 meters long and facilitates controlled electric heating. Then follows a 4 meter long adiabatic section. The condenser section is 2.5 meters long. The total length of the heat pipe is 9 meters. The individual sections are held together by EPDM connectors. The dimensions of the heat pipe are compared to the operational limits posed by the Engineering Sciences Data Unit. Then the thermal resistances of the heat pipe sections are calculated and afterwards validated. The interfacial thermal resistance between the electric heaters and evaporator wall was reduced by applying thermal conduction paste to the band heaters. It was found that at coolant flows of 1000 l/h and higher, the vapour temperature in the heat pipe drops significantly. The drop in temperature facilitates a higher heat flow through the heat pipe. Also, the resistance across the evaporator and the condenser section gets smaller for higher coolant flows. The results found are supported by theory and formulae from the Engineering Sciences Data Unit.
From Agglomerates of Spheres to Irregularly Shaped Particles: Determination of Dynamic Shape Factors from Measurements of Mobility and Vacuum Aerodynamic Diameters

With the advent of advanced real-time aerosol instrumentation, it has become possible to simultaneously measure individual particle mobility and vacuum aerodynamic diameters. This paper presents an experimental exploration of the effect of particle shape on the relationship between mobility and vacuum aerodynamic diameters. We make measurements on systems of three types: (1) Agglomerates of spheres, for which the density and the volume are known; (2) Ammonium sulfate, sodium chloride, succinic acid and lauric acid irregularly shaped particles of known density; and (3) Internally mixed particles, containing organics and ammonium sulfate, of unknown density and shape. For agglomerates of spheres we observe and quantify alignment effects in the Differential Mobility Analyzer (DMA), an important consequence of which is that mobility diameter of aspherical particles can be a function of DMA operating voltages. We report the first measurements of the dynamic shape factors (DSFs) in free molecular regime. We report the first experimental determination of DSF for ammonium sulfate particles, for which we find DSF to increase from 1.03 to 1.07 as particle mobility diameter increases from 160 nm to 500 nm. Three types of NaCl particles were generated and characterized: nearly spherical particles with DSF of ∼ 1.02; cubic with DSF that increases from 1.06 to 1.17 as particle mobility diameter increases; and compact agglomerates with DSF 1.3–1.4. Organic particles were found to be nearly spherical. The data suggest that addition of organics to ammonium sulfate particles lowers their DSF.
Effective mass and ground state of AlAs quantum wells studied by magnetoresistance measurements

Transport properties of electrons confined in AlAs quantum wells were studied using low temperature magnetoresistance measurement. The structure used is quantum wells consisting of AlAs channel layers sandwiched by Si‐doped Al0.45Ga0.55As barrier layers. This structure enables us to confine electrons in the X valleys of AlAs. The electron confinement in the AlAs quantum wells were confirmed by a mobility enhancement at low temperatures. Magnetoresistance measurements showed clear Shubnikov–de Haas oscillations for the magnetic field parallel to the growth direction. A large effective mass of (0.55±0.05) m0, which is close to √mtml (mt:transverse effective mass, ml:longitudinal effective mass), was obtained from the temperature dependence of the oscillations. This indicates that the ground state is Xx, Xy, even though Xz was expected to be the ground state due to its large effective mass parallel to the growth direction. This changeover of AlAs X valley states can most likely be attributed to a strain‐indu.
Markoff Chain Model for Growth of Polymer Single Crystals

A theory is presented wherein the development of a polymer single crystal is envisioned as the successive coherent addition of layers of segments of polymer molecules, each layer acting as the substrate for the succeeding layer. The substrate is assumed smooth and the distribution of segment lengths in the next layer is assumed to be controlled by equilibrium considerations. The theory predicts that as the supercooling is increased the energy gained due to the bulk energy of crystallization tends to overwhelm the energy lost due to formation of new surfaces. This has the result of making the average segment length of the adding layer closer and closer to the substrate length. In some cases it even exceeds the substrate length. The net result is that the temperature dependence of ultimate crystal thickness is not as great as was implied by the (ΔT)—1 laws of previous theories.The theory has been satisfactorily fitted to the experimentally observed dependence on temperature of single crystals of linear poly.
Climate variability as reflected in a regional atmospheric CO2 record

This paper analyses a 15-year long atmospheric CO2 mixing ratio record measured at a mid-continental, low-elevation station (Hegyh´ats´al, Hungary) to reveal the effect of regional climate variability. While the long-term trend and the temporal fluctuation of the growth rate of CO2 mixing ratio followthe global tendencies to a large extent, the shorter-term variations show special features. We present the distorted seasonal cycle caused by the seasonality in the atmospheric vertical mixing and the tendentious change in its shape, which can be attributed to the gradual warming and to the resulted prolongation of the growing season. The decreasing summer diurnal amplitude and the decreasing seasonal amplitude in the mixing ratio, furthermore the higher than average summer CO2 mixing ratio growth rate in the first period of the measurements (1994–2003) with generally rising temperature and decreasing precipitation are explained as the consequence of the reduced activity of the biosphere in the influence area of the station and that of the reduced biomass under environmental conditions getting increasingly unfavourable. The explanation is supported by the colocated tall tower surface–atmosphere CO2 exchange measurements and by the crop yield statistics of the dominantly agricultural region around the station.
Light emission and floating gate memory characteristics of germanium nanocrystals

We report Ge nanocrystals (NCs) based dual functional light emitting and metal insulator semiconductor (MIS) flash memory devices, fabricated by rf sputtering. Transmission electron micrographs revealed the formation of spherically shaped Ge NCs. We have observed broad electroluminescence (EL) around 760 nm, which is attributed to electron–hole recombination in quantum confined Ge NCs. The dependence of integrated EL intensity on drive currents has also been studied. An anti‐clockwise hysteresis behaviour is observed in capacitance–voltage measurements of MIS devices for different sweep voltages, indicating net electron trapping in NC based floating gates.
Anisotropic polarizability and diffusion of protein in water solutions studied by laser light scattering

Molecular mobility of protein macromolecules is determined by their net charge and the ionic strength of the solution. In this paper we report the first results of simultaneous measurement of the dynamic and static parameters of plasma blood proteins in dilute water solutions with different pH and ionic strengths. It is possible to determine such parameters of macromolecules as molecular weight, shape, surface charge and interaction force between macromolecules using the light scattering method. ' The intensity of light scattering is determined by the mean square value of the polarizability fluctuation < Ea >2.
Calculation of the van der Waals potential energy for polyethylene and polytetrafluoroethylene as two-atom and three-atom chains: rotational freedom in the crystals

The van der Waals potential energy of polyethylene and polytetrafluoroethylene has been computed as a function of both two and three angles of rotation around the bonds of the backbone chain, the bond lengths and valence angles being held fixed. The calculations show that there are more minima than is predicted by the 'equivalence principle'. The implications of these results are important in the crystalline polymers and in the physical chemistry of the polymer solutions as well as in statistical-mechanical theories. In addition the evaluation of the van der Waals potential energy in the crystal of polytetrafluoroethylene by rotating in phase the polymer chains around their helical axes suggests that, surprisingly, the macromolecules are free-rotating.
Adsorption of Leucine-Rich Amelogenin Protein on Hydroxyapatite (001) Surface through -COO - Claws

Amelogenin is the main component of the organic matrix necessary to the formation of tooth enamel by directing the hydroxyapatite (HAP) growth. However, the detailed mechanism of adsorption between amelogenin and HAP is still not clear. In this report, simulations of the dynamic behavior of six different orientations of leucine-rich amelogenin protein (LRAP), the amelogenin splice variant, on a fixed hydrophilic HAP surface (001) were performed. Energy minimization, molecular dynamics (MD), and steered molecular dynamics (SMD) simulations were integrated in carrying this study. The results are highly consistent with the previous experimental findings. It was confirmed that the carboxyl groups contributed mainly to the adsorption of LRAP on the HAP (001) surface. Moreover, it was found that the −COO- claw of LRAP grasps the calcium ion with its two oxygen atoms in a special triangle form. This interaction form can resist external forces and is the key factor of the adsorption between LRAP and HAP.
Reactivity of Vibrationally Excited Methane on Nickel Surfaces

Four-dimensional variational calculations have been performed for modeling energy flow between methane (CH4) stretching vibrational energy states as the molecule adiabatically approaches a metallic surface. The model is based on a local mode Hamiltonian for an isolated CH4 molecule and a London-Eyring-Polanyi-Sato potential describing surface–molecule interactions. The results suggest the possibility of mode specific effects on chemical reactivity. Specifically, the symmetric A1 stretch fundamental adiabatically correlates with the localized excitation in the unique CH bond pointing towards the surface. Conversely, the antisymmetric F2 stretch fundamental excitation correlates with A and E vibrations in the CH3 radical, and therefore this degree of freedom is localized away from the reactive CH bond. Landau–Zener semiclassical analysis of nonadiabatic curve crossings predicts a significant velocity dependence to the state specific energy flow dynamics. Since excitation localized in active versus spectator.