Miracle-dz/UniFAR-FTUs huggingface dataset:
Assignments of guanosine UV resonance Raman bands on the basis of13C,15N and18O substitution effects

UV resonance Raman spectra of guanosine and its seven isotope-substituted analogs (2-13C, 2-15N, 6-18O, 7-15N, 8-13C, 9-15N and 1′-13C) were measured with 257 nm excitation in H2O and D2O solutions. In-plane vibrations of the guanine ring were selectively enhanced in the UV resonance Raman spectra, and most Raman bands showed significant wavenumber shifts upon isotopic substitution. The observed isotope shifts were used to assign the Raman bands to vibrations of the peripheral sites (N1— H, C2—NH2 and C6O), the pyrimidine ring and/or the imidazole ring. Previous assignments for some Raman bands were shown to be inconsistent with the isotopic data and they were revised. Relationships between the vibrational modes and the sensitivities to hydrogen bonding or conformation are discussed for known Raman marker bands. Each hydrogen bond marker arises from a vibration that involves, at least partly, the proton donor or acceptor atom. All the marker bands of glycosidic bond orientation and ribose ring puckering actually involve atomic displacements around the N9—C1′ moiety connecting the guanine ring to ribose, permitting vibrational coupling between them. The isotopic wavenumber shifts reported here may be useful in improving the force field for the 9-substituted guanine ring and in interpreting the vibrational spectra of guanine nucleoside and nucleotides. Copyright © 1999 John Wiley & Sons, Ltd.
Three-Dimensional Simulation of Brownian Motion of Nano-Particles In Aerodynamic Lenses

A computer code for analyzing nano-particle motions in an aerodynamic particle beam focusing system was developed. The code uses an accurate three-dimensional model for the Brownian diffusion of nano-particles in strongly varying pressure field in the aerodynamic lens system. Lagrangian particle trajectory analysis was performed assuming a one-way coupling model. The particle equation of motion used included drag and Brownian forces. The prediction of the 3-D model for penetration efficiency, beam divergence angle, beam diameter and radial cumulative fraction were evaluated and were compared with those of the axisymmetric models. The simulation results showed that for particle diameters less than 30 nm in helium gas, the Brownian force could significantly affect the beam focusing and particle penetration efficiency. Some potential errors in the naíve usage of axisymmetric model were discussed. It was shown that the earlier axisymmetric models lead to the incorrect mean square radial displacement of Brownian particles. The present 3-D approach, however, leads to the correct value of the radial mean square displacement of 4Dt. The effect of the inlet orifice and relaxation region on the performance of the lens system was also investigated. It was shown that the major losses of the 4 to 10 nm particles occur in the inlet orifice and relaxation region walls. For 15 to 30 nm particles, the main losses occur at the inlet orifice walls. Some alterations of the shape of the inlet orifice were examined and a new design is suggested to reduce the loss of the particles at the inlet flow control orifice.
The Effect of Solution pH on the Structure of Lysozyme Layers Adsorbed at the Silica−Water Interface Studied by Neutron Reflection

We have studied the structure of lysozyme layers adsorbed at the silica−water interface using specular neutron reflection. The effect of pH on the adsorbed lysozyme layer was examined by manipulating the pH in two different cycles at two constant lysozyme concentrations of 0.03 and 1.0 g dm-3; the first cycle was started at pH = 4 followed by pH = 7 and then 8, before returning to 4; the second cycle was started at pH = 7 followed by a decrease to 4 and then back to 7. The neutron reflectivity profiles showed no hysteresis in either adsorbed amount or structure. There was less adsorption at pH = 4 than at pH = 7 for both lysozyme bulk concentrations. No variation of the reflectivity with time was found at the experimental resolution of about 5 min per measurement. The lysozyme structure at the interface at pH = 4 and pH = 7 was determined from reflectivity profiles at different isotopic compositions of the water. The thickness of the adsorbed layer at the lower concentration of 0.03 g dm-3 was found to be.
Crystal structure of [cinnamato-[tris(1-methylbenzimidazol-2-ylmethyl)- amine]-zinc(II)] perchlorate —dimethylformamide — methanol (1:1:2:0.5), [Zn(C27H27N7)(C9H7O2)](ClO4) · 2(CH3)2NCHO · 0.5CH3OH

C42.50H50ClN9O8. 50Zn, monoclinic, C12/c1 (no. 15), a = 33.201(1) Å, b = 15.3991(4) Å, c = 22.3422(7) Å, 5 = 128.686(1)°, V = 8916.8 Å, Z = 8, Rgt(F) = 0.054, wRref(F ) = 0.170, T = 153 K. Source of material Reagents and solvents used were of commercially available quality. To a stirred solution of tris(1-methylbenzimidazol-2ylmethyl)amine (89.9 mg, 0.2 mmol) in hot MeOH (10 ml) Zn(ClO4)2 (H2O)6 (74.5 mg, 0.2 mmol) was added , followed by a solution of sodium cinnamate (34.0 mg, 0.2 mmol) in MeOH (5 ml). A colorless crystalline product formed rapidly. The precipitate was filtered off, washed with MeOH and absolute Et2O, and dried in vacuo. The dried precipitate was dissolved in DMF to form a colorless solution that was allowed to evaporate at room temperature. Colorless crystals suitable for X-ray diffraction studies were obtained after three weeks (yield, 64%). Elemental analysis ! found: C, 55.44 %; H, 5.17 %; N, 13.58 %; calculated for C42.5H50N9O8. 5ClZn:C, 55.26 %; H, 5.46 %; N, 13.65 %. Experimental Details All H atoms were found in difference electron maps and were subsequently refined in a riding-model approximation with C—H distances ranging from 0.95 to 0.99 Å and O—H distance 0.84 Å and Uiso(H) = 1.2 Ueq of the carrier atom.
Carbon Nanotube Electron Sources for Electron Microscopes

Publisher Summary Electron sources were constructed from individual multi walled carbon nanotubes with closed caps and thoroughly cleaned surfaces. Nanotubes from both chemical vapor deposition growth and arc discharge growth were investigated. These emitters provide a highly stable emission current up to a threshold current of a few microamperes. At too-large currents several processes occurs such as splitting, breaking, and cap closing. The emission process is field emission for a work function of 5eV. The electron optical performance is highly beneficial for use of carbon nanotubes as high-brightness point sources in electron microscopes and advantageous with respect to state-of-the-art electron sources. The industrial process is needed to mount a closed-cap carbon nanotube inside an electron miroscope so that it provides an electron beam with a cone around the optical axis of the microscope. This requires not only that the carbon nanotube is mounted in a direction parallel to the optical axis, but also that the cap structure is defined such that the electrons are emitted primarily in a forward direction.
Structure/properties of conjugated conductive polymers. 1. Neutral poly(3-alkythiophene)s

Soluble conjugated poly(3-alkythiophene)s (P3ATs) including poly(3-butylthiophene) (P3BT), poly(3-octylthiophene) (P3OT), and poly(3-dodecylthiophene) (P3DDT), were prepared chemically and characterized. It is found that each of the P3ATs consists of an ordered phase and a disordered phase. In the ordered phase, the side chains are nearly fully extended and are packed to give a two-layer structure and one-layer structure, the former being the majority. The coplanar subchains are stacked to form planes, and the space between two successsive stacking planes is filled with aligned side chains
Mucin aggregation from a rod-like meso-scale model

Dissipative particle dynamics, a meso–scale particle-based model, was used to study the aggregation of mucins in aqueous solutions. Concentration, strength of the mucin–water interactions, as well as the effects of size, shape, and composition of the model molecules were studied. Model proteins were represented as rod-like objects formed by coarse-grained beads. In the first model, only one type of beads formed the mucin. It was found that all the surfaces were available to form aggregates and the conformation of the aggregates was a function of the strength of the mucin–water interaction. With this model, the number of aggregates was unaffected by the initial position of the mucins in the simulation box, except for the lowest mucin concentration. In a more refined mucin model, two kinds of beads were used in the molecule in order to represent the existence of cysteine-like terminal groups in the actual molecule. With this new scheme, aggregation took place by the interaction of the terminal groups between model molecules. The kinetic analysis of the evolution of the number of aggregates with time was also studied for both mucin models.
Paschen law for argon glow discharge

Electric discharge between two electrically charged surfaces occurs at a well-defined, gas-dependent combination of atmospheric pressure and the distance between those surfaces, as described by Paschen's law. The understanding of when the discharge will occur in an Ar discharge is essential basic knowledge. A glow discharge apparatus was used in this experiment of Ar discharge at a pressure range between 2.0 Torr and 12 Torr, a power of 20 W and 40 l/min flow rate of gases. The optical emission spectroscopy was carried out in the wavelength range of 200 to 1100 nm. Here, we present experimentally measured plasma Paschen curves for Ar gas and compare our results of breakdown voltages with the literature. The minimum voltage measured for a discharge in Ar atmosphere was 215 ± 2.2 at 0.7 Torr-cm, which agree with previous measurements.
Luminescence from cerium(III) acetate complexes in aqueous solution: considerations on the nature of carboxylate binding to trivalent lanthanides

The luminescence of cerium(III) has been studied in aqueous solutions in the presence of acetate ion. In contrast to previous reports that cerium(III) carboxylate complexes do not luminesce, a weak emission is observed, which has a similar spectrum to the aquo cerium(III) species but a much shorter lifetime. Results from a variety of studies on complexation of various trivalent lanthanide ions with carboxylates, including NMR spectral and relaxation measurements, molecular mechanics calculations, deuterium isotope effects on Tb(III) luminescence lifetimes, together with literature data strongly suggest that the dominant mode of complexation between carboxylates and trivalent lanthanides involves a weak, predominantly bidentate, binding to the metal cation. We suggest that the observed emission arises from a 1 : 1 cerium acetate species involving such bidentate coordination.
A learning algorithm for the calibration of internal model uncertainties in advanced wind turbine controllers: A wind speed measurement-free approach

Wind turbine partial-load controllers have evolved from simple static nonlinear function implementations to more advanced dynamic controller structures. Such dynamic control schemes have the potential to improve power production performance in realistic environmental conditions and allow for a more granular trade-off between loads and energy capture. The control structure generally consists of a wind speed estimator (WSE) combined with a controller aiming to track the commanded tip-speed ratio (TSR) reference. The performance and resulting closed-loop system stability are however highly dependent on the accuracy of the internal model in the WSE-TSR tracking scheme. Therefore, developing learning algorithms to calibrate the internal model is of particular interest. Previous works have proposed such algorithms; however, they all rely on the availability of (rotor-effective) wind speed measurements. For the first time, this paper proposes an excitation-based learning algorithm that exploits the closed-loop dynamic structure of the WSE-TSR tracking scheme. This algorithm calibrates the internal model without the need for wind speed measurements. Analysis and simulations show that the proposed algorithm corrects for model uncertainties in the form of magnitude scaling errors under ideal constant and realistic turbulent wind conditions.
Surface spectroscopic study of the adsorption of Ni(II) on pyrite and arsenopyrite at pH 10

The sorption mechanism of Ni(II) on pyrite (FeS 2 ) and on arsenopyrite (FeAsS) has been investigated at pH 10, using complementary methods for surface characterization such as x-ray photoelectron spectroscopy (XPS), Fourier transform mass spectrometry (FTMS), high-frequency dielectric measurements and electrophoretic mobility measurements. At this pH, the surfaces of the minerals are rapidly covered by an oxidation layer composed mainly of Fe(III) oxides on FeS 2 and Fe(III) arsenite and arsenate on FeAsS and presenting negative zeta potentials of -40 and -60 mV, respectively. The first step of the interaction with Ni(II) is the formation of a hydroxylated surface complex through proton exchange with the surface hydroxyl groups (≡Fe-OH). Then, electrostatic interactions between colloidal Ni(II) and the surface produce a heterogeneous coating of an average thickness of a few nanometres. This film inhibits significantly the oxidation by H 2 O 2 of these two minerals, particularly FeAsS.
Elastic and electronic properties of hexagonal rhenium sub‐nitrides Re3N and Re2N in comparison with hcp‐Re and wurtzite‐like rhenium mononitride ReN

Very recently, two hexagonal rhenium sub‐nitrides Re3N and Re2N, which belong to a rather rare group of known metal‐rich (M/N > 1) nitrides of heavy 4d, 5d metals, have been successfully synthesized, and their potential technological applications as ultra‐incompressible materials have been proposed. In this work, we present a detailed ab initio study of recently synthesized rhenium sub‐nitrides in comparison with hcp‐Re and wurtzite‐like rhenium mono‐nitride ReN, with the purpose to evaluate the trends of the elastic, electronic properties, and chemical bonding in the series of these hexagonal systems as a function of the Re/N stoichiometry: Re → Re3N → Re2N → ReN.
Radical scavenging potential of compounds isolated from Vitex agnus-castus

Nine secondary metabolites-artemetin (1), casticin (2), 3-hydroxy-5,6,7,4'-tetramethoxy flavone U(3), penduletin (4), p-hydroxybenzoic acid (5), methyl 3,4-dihydroxybenzoate (6), methyl isovanillate (7), vanillic acid (8), and 3,4-dihydroxybenzoic acid (9)-were isolated from a folkloric medicinal plant, Vitex agnus-castus. The structures of compounds 1-9 were identified using spectroscopic techniques. Compound 7 was isolated for the first time from this plant. These compounds were screened for their antioxidant activity. Compounds 6 and 9 exhibited significant activity against the DPPH free radical.
Recursive and Sequential Tests of the Unit-Root and Trend-Break Hypotheses: Theory and International Evidence

This paper investigates the possibility, raised by Perron (1989, 1990a), that aggregate economic time series can be characterized as being stationary around broken trend lines. Unlike Perron, we treat the break date as unknown a priori. Asymptotic distributions are developed for recursive, rolling, and sequential tests for unit roots and/or changing coefficients in time series regressions. The recursive and rolling tests are based on a time series of recursively estimated coefficients, computed using increasing subsamples of the data. The sequential statistics are computed using the full data set and a sequence of regressors indexed by a "break" date. When applied to data on real postwar output from seven DECO countries, these techniques fail to reject the unit root hypothesis for five countries (including the U.S.), but suggest stationarity around a shifted trend for Japan.
Tight-binding approach to calculation of localised perturbations in semiconductors

The replacement of As by N in GaAs introduces several pertubations, including both a change in potential at the N site and also long range strain relaxation in the crystal. It can be very useful to describe this perturbation in terms of the change in the Hamiltonian, ΔH, due to the introduction of N. Using plane-wave approaches, ΔH treats explicitly all atomic displacements in the structure. By contrast, a tight-binding approach allows a much simpler analysis. We illustrate the benefits of the tight-binding method by considering Ga(P,As:Bi) and GaNAs. We show that the tight-binding method provides a clear and quantitative explanation for many of the unusual electronic properties of these and related alloys, including the nonmonotonic variation of electron effective mass, me, and gyromagnetic ratio, ge, in GaNAs.
A time‐resolved study of rotational energy transfer into A and E symmetry species of 13CH3F

Rotational energy transfer processes into the A and E symmetry species of the symmetric top molecule 13CH3F have been studied. In this time‐resolved double resonance experiment a tunable millimeter/submillimeter wave spectrometer was used to monitor the change in strength of rotational transitions in the ν3 vibrational state after a Q‐switched CO2 laser pumped the K=3, J=5 level in ν3. A simple numerical simulation of rotational energy transfer allowed the 13CH3F system to be modeled and collisional energy transfer rates to be obtained from the data. Two important processes were studied. The first, a process that obeys the spin statistic selection rule ΔK=3n has a rate of 29±6 ms−1 mTorr−1. The second, a vibrational quantum number swapping collision that effectively transfers population between the A and E symmetry species and thereby transcends the spin statistic selection rule, has a rate of 6.6±0.7 ms−1 mTorr−1, about 1.4 gas kinetic collisions. The numerical simulations and these rates, along with pre.
Experimental review of high multiplicity reactions

The most relevant experimental information presented at this Conference on high energy inclusive and semi-inclusive reactions is summarized. The aim of the present review is to identify possible asymptotic properties (as scale invariance) and to disentangle different production mechanisms, with particular emphasis on the diffractive component. A detailed discussion of new data on the two-body correlation function is given in order to provide a first insight in the dynamical features of multiparticle production. Finally the most recent results and semi-empirical fits to the multiplicity distributions are presented.
The Burke-Schumann Diffusion Flame With Zero Net Flux Boundary Conditions

Abstract A zero net flux boundary condition is applied to the classical Burke-Schumann diffusion flame. The numerical results indicate that the conventional constant boundary condition is valid only at a high Reynolds number (Re ⩾ 100) and strong back diffusion appears at low Reynolds numbers. The importance of applying this boundary condition in modelling of composite propellant combustion is also discussed.
Quantitative Analysis of Flavonoids and Phenolic Acids in Propolis by Two-Dimensional Thin Layer Chromatography

Flavonoids are polyphenolic compounds present in a wide variety of plants. They are benzo-γ-pyrone derivatives, which resemble coumarin. Flavonoids (with other polyphenols, e. g. phenolic acids) are believed to have a variety of physiological activity. One of the most concentrated sources of those compounds is propolis, a resinous substance collected by the honeybees from various plant sources. Its composition, and thus its content of pharmacologically active compounds, depends on geographic origin. We have developed a new TLC method suitable for analysis of complex mixtures such as propolis. Two-dimensional TLC with densitometry evaluation seemed an appropriate method for rapid screening of active compounds and quantifying the concentration of flavonoid aglycones and phenolic acids present in propolis extracts. After developing the method we tested it by analyzing and comparing the composition of three raw propolis samples from different geographic regions of Croatia. To establish the RF values, standard solutions of nine flavonoids and six phenolic acids were first applied to the chromatographic plate as 10-mm bands. Plates were developed in vertical glass chambers previously saturated with the mobile phases - n -hexane-ethyl acetate-glacial acetic acid, 31 + 14 + 5 (v/v), (mobile phase 1) or chloroform-methanol-formic acid, 44 + 3.5 + 2.5 (v/v), (mobile phase 2). After drying, bands were visualized under short- and long-wavelength UV light; the plates were then sprayed with 1% AlCl3 ethanol solution and viewed again under long-wavelength UV light. RF values were calculated. All standards were chromatographed again in groups of 3 or 4 together with a propolis extract. First, plates were developed with mobile phase 1 (or 2), the mobile phase was evaporated, standard solutions were applied again, and the plate was rotated through 90° and chromatographed again with mobile phase 2 (or 1). The presence (or absence) of all standards was determined according to their RF values and fluoresfluorescence colors. Abetter combination of mobile phases was chosen, the amounts of standards present were adjusted, and the standards were again individually chromatographed with the propolis extract. Quantitative evaluation was performed with Camag Reprostar 3 densitometer. Two-dimensional TLC was shown to be a highly suitable method for the task. We proved the method could be used for analysis of different propolis samples to identify and quantify the main pharmacologically active compounds.
Temperatures: old, new and middle aged

This study explores the various ways in which a ‘temperature’ can be introduced and calculated in a molecular simulation. We focus on the relatively recent formula of Rugh, and a simplified version called the ‘configurational’ temperature, T config, which became popular after Rugh's work. We derive formulae for these various ‘temperatures’ for the special case of the soft–sphere fluid, with the pair interaction, , where ε and σ set the energy and length scales, respectively, and for different n values. We show with a number of simple test cases that the various prescriptions of temperature give the same result as the thermodynamic temperature at equilibrium. Although much of the current work uses the configurational temperature, Rugh's temperature, T R, has the advantage that it has the thermodynamic value in circumstances where the configurational temperature is not defined (such as in the limit of the ideal gas, where Rugh's temperature becomes the kinetic temperature). The configurational temperature is a particular example of the hypervirial theorem. Using the particle forces and their gradients, we calculate the first and second hypervirial temperatures, which we find to be equal, even though the force moments (i.e. ) and their derivatives themselves do not conform to a Gaussian distribution. Various moment ratios were shown to have a linear dependence on the reciprocal of the density, at not too high densities. We explored the behaviour of the kinetic and configurational temperatures for some non–equilibrium systems, where quite different trends were observed in these two quantities in any transient or non–stationary stage. The kinetic temperature was found to respond more rapidly to perturbations than the configurational temperature, as might be expected since usually energy is more rapidly transported than matter.
Physical and Mechanical Properties of Blends Based on Poly (dl-lactide), Poly (l-lactide-glycolide) and Poly (ϵ-caprolactone)

Bioresorbable materials are extensively used for a wide range of biomedical applications. In this study, the common industrial processes of compression moulding and solvent casting were utilised for initial preparation of thin film blends based on Poly (dl-lactide), Poly (l-lactide-glycolide) and Poly (ϵ-caprolactone). Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), phosphate buffered saline adsorption, tensile testing and contact angle measurement were used as a means of investigating the physical and mechanical properties of the blends.