Miracle-dz/UniFAR-FTUs huggingface dataset:
Thermally Induced Association and Dissociation of Methylcellulose in Aqueous Solutions

Aqueous solutions of a methylcellulose, ranging from 0.30 to 2.49 wt %, were studied by means of micro differential scanning calorimetry (micro DSC) and rheology. The effects of polymer concentration on the thermodynamic properties of these solutions were examined through a heating process and a following cooling process at a fixed rate of 1 °C/min. Upon heating, an endothermic peak was observed at about 63 °C, which was independent of polymer concentration. The total energy defined by the endothermic peak area was found to be a linear function of polymer concentration. On the other hand, when samples were cooling from about 90 °C, a broad exothermic peak appeared at about 33 °C, and the peak height and its broadness increased with polymer concentration. A shoulder was observed above the peak temperature of 33 °C, and the shoulder became more prominent with increasing polymer concentration to eventually appear as a second peak at about 40 °C. The thermal analysis results clearly show that the association .
Spontaneous symmetry breaking and control of the radiation from microlaser
 arrays

References [1] Haelterman and P. Mandel, Opt. Lett. 15, 1412 (1990); [2] N. Akhmediev and A. Ankiewicz, Phys. Rev. Lett. 70, 2395 (1993); [3] B. A. Malomed, Spontaneous Symmetry Breaking, Self-Trapping, andJosephson Oscillations (Springer, Berlin, Heidelberg, 2013); [4] C. W. Hsu, et al, Nat. Rev. Mater. 1 (2016); [5] D. C. Marinica, et al, Phys. Rev. Lett, 100, 183902, 2008; [6] S. D. Krasikov, et al, Phys. Rev. B97(2018). The effect of spontaneous symmetry breaking is well known in the dynamics of the nonlinear waves. The essence of the effect is that, although a symmetric system always possesses a symmetric solution, this solution must not necessarily be stable. The instability of the symmetric state results in the switching of the system to another state that can be asymmetric. In nonlinear optics this effect was first revealed in two-beam nonlinear Fabry-Perot interferometer [1], see Fig.1a, and later was widely studied in many optical systems [2,3]. This effect is highly important in optical systems which can provide so-called “Bound State in the Continuum” (or “BIC”) [4,5]. BIC is a special high-Q state, which coexist with continuous spectrum of radiating waves, but remains localized. Such unusual behavior can be explained by destructive interference of leaky modes in the system, see Fig. 1b. Therefore, BIC is uncoupled with incoming pumping radiation and can not be excited directly. But because of the nonlinearity and symmetry breaking bifurcation the parametric excitation of BIC can take place. As a result a quasi-BIC appears, which is still high-Q [6].
Proton transfers in hydrogen-bonded systems. 2. Electron correlation effects in diamminehydrogen(1+)

Potentials for transfer of the central proton between the NH/sub 3/ units of (H/sub 3/NHNH/sub 3/)/sup +/ are calculated via ab initio methods ar several levels of sophistication. Double-well potentials are obtained for all internitrogen distances studied which vary between 2.73 and 3.15 A. All methods indicate that the energy barrier to proton transfer increases as the two NH/sub 3/ molecules are further removed from one another. Treatment of electron correlation via the polarization configuration interaction (POL-CI) method leads to barriers substantially smaller than those obtained by restricted Hartree-Fock calculations with use of a basis set of double zeta plus polarization function (RHF/DZP) quality. Inclusion of only intrapair correlations involving the two nitrogen lone pairs with use of the generalized valence bond (GVB) method leads to no decreases in the barriers relative to the DZP Hartree-Fock estimates. Use of the smaller split valence 4-31G basis produces barriers intermediate between the RHF/DZP and POL-CI results. Proton transfers in (N/sub 2/H/sub 7/)/sup +/ in the gas phase are studied using both a rigid model and one which includes relaxation of the R(NN) distance during proton motion. The latter relaxation results in a lowering of the POL-CI barrier from 3.5 to 1.5 kcal/mol.more » 2 figures, 4 tables. « less
Graphite oxide as a dehydrative polymerization catalyst: A one-step synthesis of carbon-reinforced poly(phenylene methylene) composites

The synthesis and characterization of poly(phenylene methylene) (PPM) and carbon composites thereof are described. The materials were prepared using graphite oxide (GO), which was discovered to function in two distinct roles. First, the GO was found to facilitate the dehydrative polymerization of benzyl alcohol (BnOH) to form PPM. Second, the residual carbon from the GO catalyst, having undergone thermal deoxygenation during the polymerization reaction, served as a graphene-like additive in the resulting composite. While pure (i.e., additive-free) PPM was found to be mechanically compliant (E′ = 40 MPa), inclusion of 0.1 wt % GO in the starting reaction mixture improved the material’s mechanical properties significantly (E′ = 320 MPa). Homogeneous dispersion of the additive in the matrix was confirmed by powder X-ray diffraction (PXRD) analysis, Raman spectroscopy, and transmission electron microscopy (TEM). The carbon additive was separated from the PPM via trituration in dichloromethane, and the GO star.
Bond Graph Support in SystemC AMS

SystemC AMS is a simulation framework, which is used for the hardware/software co-design of heterogeneous systems on chip. The increasing integration of digitally-assisted multiphysical components into these systems makes the bond graph formalism an excellent candidate to augment the modeling capabilities of SystemC AMS to enable the description of their energy-conserving behavior. Bond graphs integrate well with the block diagram formalism to describe continuous-time non-conservative behavior. The latter formalism also facilitates a seamless interaction with models using the Discrete Event (DE) and Timed Data Flow (TDF) models of computation of SystemC AMS. Therefore, both formalisms have been implemented into a dedicated Bond Graph (BG) model of computation for SystemC AMS, which architecture and usage is presented. The system model of a vibration sensor and its digital front end serves as an example how the different models of computation can be used in parallel to describe the individual component behaviors in a well adapted way.
N,N′-dimethylperylene-3,4,9,10-bis(dicarboximide) on alkali halide (001) surfaces

The growth of N,N′-dimethylperylene-3,4,9,10-bis(dicarboximide) (DiMe-PTCDI) on KBr(001) and NaCl(001) surfaces has been studied. Experimental results have been achieved using frequency modulation atomic force microscopy at room temperature under ultrahigh vacuum conditions. On both substrates, DiMe-PTCDI forms molecular wires with a width of 10nm, typically, and a length of up to 600nm at low coverages. All wires grow along either the [110] direction (or [11¯0] direction, respectively) of the alkali halide (001) substrates. There is no wetting layer of molecules: atomic resolution of the substrates can be achieved between the wires. The wires are mobile on KBr but substantially more stable on NaCl. A p(2×2) superstructure in a brickwall arrangement on the ionic crystal surfaces is proposed based on electrostatic considerations. Calculations and Monte Carlo simulations using empirical potentials reveal possible growth mechanisms for molecules within the first layer for both substrates, also showing a sign.
Multiple steady states in a CSTR with total condenser: Comparison of equilibrium and nonequilibrium models

Comparison of equilibrium and nonequilibrium models of a CSTR with total condenser focused on the multiple steady states and dynamic behaviour was carried out. The steady-state behaviour of the model system, MTBE synthesis from methanol and isobutene in a reactive distillation column, was studied in terms of the input parameters, i. e. feed flow rate of methanol or butenes, reflux ratio, and mass of catalyst. The dynamic behaviour of the system during the start-up was investigated and perturbations of manipulated variables were found to cause transitions between the parallel steady states.
Poly(ethylene oxide)/Silica Nanocomposites: Structure and Rheology

The effects of polymer−particle and particle−particle interactions on viscoelastic properties of nanocomposite materials are investigated using narrow molecular weight distribution poly(ethylene oxide) (PEO) containing isotropic silica nanospheres. Nanocomposites are prepared using a “freeze-drying” method to guarantee homogeneous dispersion of silica. The dispersion state of silica nanospheres is characterized by atomic force microscopy phase contrast imaging, and mechanical rheometry is used to study relaxation dynamics and viscoelastic properties of these materials in the melt state. Linear viscoelastic data indicate a transition to a solidlike response at low oscillation frequencies for particle volume fractions φ as low as 2%, dramatically lower than the theoretical percolation threshold (φ ∼ 30%). Nanoparticle volume fraction, surface chemistry, and PEO molecular weight are all found to strongly influence nanocomposite structure and dynamics. A filler networking mechanism, wherein nanosized silica p.
Water-Soluble, Cyclodextrin-Modified CdSe−CdS Core−Shell Structured Quantum Dots

β-Cyclodextrin (β-CD)-modified CdSe (β-CD/CdSe) and CdSe−CdS core−shell structured (β-CD/CdSe−CdS) quantum dots (QDs) were synthesized by a single-phase approach in aqueous solutions. These receptor-modified QDs are very soluble and stable in water over a wide range of pH values and ionic strengths. Coating a CdS shell on the CdSe core greatly increased the quantum yield (QY) of original CdSe QDs. Photoactivation of these particles by the room light results in 46% QY for β-CD/CdSe−CdS in water. The surface-anchored β-CD still retains its host capability for the complexation of different organic species in aqueous solutions. More interestingly, the fluorescence sensitivity of these QDs to the same substrate is ten times higher than that of their counterparts reported in our previous work. Furthermore, the fluorescence of these receptor-modified QDs could be reversibly tuned in two directions, enhancement or quenching, by selectively introducing different redox-active substrates in aqueous media.
Vapor Phase Growth and Imaging Stacking Order of Bilayer Molybdenum Disulfide

Various stacking patterns have been predicted in few-layer MoS2, strongly influencing its electronic properties. Bilayer MoS2 nanosheets have been synthesized by vapor phase growth. It is found that both A-B and A-A′ stacking configurations are present in bilayer MoS2 nanosheets through optical images, and the different stacking patterns exhibit distinctive line shapes in the Raman spectra. By theory calculation, it is also concluded that the A-B and A-A′ stacking are the most stable and lowest-energy stacking in the five predicted stacking patterns of bilayer MoS2 nanosheets, which proves the experimental observations.
A model of low‐frequency Raman scattering in glasses: Comparison of Brillouin and Raman data

A model of the low‐frequency Raman scattering intensity in glasses is proposed, which describes the spectrum in the region of the boson peak, typical of glasses. The model considers the boson peak as a result of first‐order light scattering by harmonic quasilocalized vibrations. The amplitude, frequency, and polarization dependence of the light on the vibrational coupling coefficient C(ω) are estimated. The model predicts a linear frequency dependence of C(ω) in the region of the boson peak and the depolarization ratio as a function of the relative contribution of the longitudinal and transverse‐type motions which comprise these quasilocal vibrational modes. Low‐frequency Raman and Brillouin measurements have been made on SiO2 glass in order to check the predictions of the model regarding the amplitude and integrated intensity of the boson peak. The estimated ratio of these values to those of the Brillouin lines are in good agreement with experiment. Comparison of the theoretical and experimental values o.
Profile shape functions in Rietveld refinements

Reflection profile functions used or suggested for use in Rietveld refinements with fixed-angle or fixed-wavelength powder diffraction data, obtained with neutrons or with X-rays, are reviewed briefly. The fixed-wavelength X-ray case is considered in detail. In tests of fitting to individual resolved reflection profiles, at least eight different profile functions, including some representations consisting of "learned' differentiable number arrays, have been show to be satisfactory at the less than 3% misfit level. Several authors have made comparative studies of subsets of the six analytic functions, Gaussian (G), Lorentzian (L), modified Lorentzian (ML), intermediate Lorentzian (IL), pseudo-Voigt (p-V), and Pearson VII (PVII). In this work, the performance of all six, in Rietveld refinements with data sets from seven different specimens with differing degrees of broadening, have been intercompared on the basis of difference plots, Rwp, and RB. The Gaussian function was consistently the worst performer, while the pseudo-Voigt and Pearson VII were the best. For this reason, for reasons of simplicity, and for convenient though crude physical interpretation of the Lorentz-fraction parameter, the pseudo-Voigt is identified as the function of choice among these six. It is emphasized that a need still exists for a better profile function soundly based on physical reality.
Distribution of End Groups within a Dendritic Structure: A SANS Study Including Contrast Variation

We present an analysis of the distribution of end groups within a urea-functionalized poly(propyleneamine) dendrimer of the fourth generation by small-angle neutron scattering (SANS). The phenyl end groups have been deuterated to enhance their contrast. The SANS experiments are performed using solution of the labeled dendrimer in mixtures of protonated and deuterated dimethylacetamide (DMA). In this way the contrast between the solute and the solvent is varied in a systematic fashion (contrast variation). The analysis presented here gives three partial scattering functions that depend differently on contrast. From these data, the scattering length density within the dendritic structure can be derived. All results show that the end groups are dispersed throughout the dendrimer with a broad maximum located at a radial distance that corresponds to ca. half of the overall size of the molecule. Hence, there is no well-defined surface of a dendritic structure defined by the end groups, but the end groups are mo.
Studies on the induction of chlorophyll fluorescence in barley protoplasts. II. Resolution of fluorescence quenching by redox state and the transthylakoid pH gradient

During the chlorophyll fluorescence oscillation described in barley protoplasts (Quick & Horton, Proc. R. Soc. Lond. B 220, 361-370, 1984) the components which contribute to quenching have been quantified. Quenching due to oxidized Q (qQ) was measured either by DCMU addition or by light doubling and indicated an oscillation in the redox state of Q which was antiparallel to the rate of oxygen evolution but was approximately 15 s out of phase at a variety of light intensities and temperatures. An oscillation in the extent of energy-dependent quenching, qe, was observed in strong but not weak light. These results are discussed in terms of the mechanism of the changes in energy and redox states that can contribute additively but in differing proportions to the fluorescence oscillation.
The Effects of Soret Diffusion on Extinction Limit in Premixed and Diffusion Counterflow n-Butane/Air Flames

The effect of Soret diffusion on flame burning intensity and extinction limit in rich/lean premixed counterflow and diffusion counterflow n-butane/air flames was computationally studied using a detailed reaction mechanism and transport properties. Through temperature sensitivity analysis of the point at the strain rate of near-extinction, it is found that the most important species affecting the flame burning intensity is the H radical in both premixed and diffusion counterflow flames. However, the Soret diffusion of the H radical has almost no influence on the flame burning intensity and extinction limit in rich/lean premixed counterflow n-butane/air flames for the narrow overlap region consisting of weakened rear part of gradT/T profile and reduced front part of H mole fraction profile. The essential reason for such an overlap region is due to the inherent feature of heat release rate and broader consumption layer of H in premixed n-butane/air flames. Unlike the premixed counterflow flames, the diffusion counterflow flame is more prone to extinction for considering Soret effect, while such effects are less than 3%. It is found that the Soret diffusion drives the heavy species C4H10 away from the flame and therefore reduces the total enthalpy supplied to the reaction zone. This is the reason why the total Soret effect weakens the burning intensity and extinction strain rate in the counterflow diffusion flame. It is demonstrated that the effects of Soret diffusion of heavy species play more important role than light species H and H2 in such flames.
Identification of Natural and Early Synthetic Textile Dyes with HPLC and UV/Vis-Spectroscopy by Diode Array Detection

Abstract The separation and identification of complex mixtures of natural and synthetic textile dyes was investigated using HPLC with diode array detection. Separation was carried out on a reversed phase column with acetonitrile-phosphoric acid gradient elution. The results show that the anthraquinones from madder root and the insect dye cocheneal present in ancient red dyes can easily be distinguished from azo-dyes present in later textile fibres. They further show that for an analysis of the numerous flavones and flavonoles, constituting most of the yellow natural dyestuffs, the combination of HPLC with on-line optical spectroscopy is particularly useful. Even when retention times are identical - as for instance for quercetin and luteolin - the ratio of a mixture can still be estimated by evaluating the ratio-chromatogram.
Simulated annealing and kriging method for identifying the spatial patterns and variability of soil heavy metal

Abstract Environmental data, including information regarding soil heavy metals, may contain significant uncertainty and exhibit a skewed distribution with a complex and unexplainable spatial variation. This study identified the spatial patterns and variations of soil heavy metals (Cu, Cd, Hg, and Pb) in the northern part of Changhua County in Taiwan to clarify the characteristics and pollution of soil heavy metals. The spatial maps of soil heavy metals were also estimated and simulated using kriging and simulated annealing methods. Correlation analysis indicated that Pearson and Spearman correlation coefficients among these four heavy metals were significant; between Cd and Cu, these two correlation coefficients were strongly significant. As expected, the spatial maps of estimation and simulation of soil heavy metals revealed high concentration areas of Cd, Cu along the main irrigation‐ditch system and surrounding industrial plants in the area of study. In addition to reproducing the spatial variation of the investigated Cd, Cu, Hg and Pb, simulated annealing could also identify the global spatial continuity and discontinuity patterns of soil heavy metals. Kriging and simulated annealing methods can both be applied to identify pollution sources and patterns for monitoring and remedy.
Evolution of the Volatile Components of an Artisanal Blue Cheese During Ripening

Abstract The volatile fraction of artisanal Gamonedo blue cheeses has been obtained by simultaneous distillation and extraction and then analyzed by gas chromatography and mass spectrometry. About 40 compounds were identified and quantitatively determined among more than 100 detected components. The evolution of some of these compounds during the ripening process has been studied. The simultaneous distillation and extraction fractions of ripe cheeses were very rich in FFA, methyl ketones, and 2-alkanols. The odd-carbon numbered ketones (especially 2-heptanone and 2-nonanone) were most abundant, and 2-heptanol and 2-nonanol were the most important among the alcohols. Methyl ketones and 2-alkanols increased during the first part of the ripening process, decreasing after 60 d. The evolution of the methyl and ethyl esters in the volatile fraction was also studied.
Isolation of New Metabolites from Aspergillus sydowi and Structure of Sydowic Acid

Four new metabolites have been isolated from Aspergillus sydowi and named sydowic acid, sydowinin A, sydowinin B, and sydowinol, respectively. Sydowic acid, C15H20O4, forms colorless needles, mp 151°C, [α]d–6.4°. Sydowinin A, C16H12O6, forms pale yellow needles, mp 218~220°C. Sydowinin B, C16H12O7, forms yellow needles, mp 220°C. Sydowinol C16H14O7, forms yellow needles, mp 157~159°C, [α]d–51° The structure of sydowic acid was shown to be represented by formula I on the basis of spectroscopic data.
Natural Fats and Oils—Renewable Raw Materials for the Chemical Industry

Since last century, the supply of raw materials for the chemical industry has undergone a radical change. Whereas at the beginning of the nineteenth century the demand for basic chemicals was satisfied entirely by renewable raw materials, from about 1850 the chemical industry came to rely increasingly upon coal. In the 1940's, mineral oil started to become increasingly important, and during the past thirty years it has remained by far as the most important source of raw materials. Renewable raw materials are likely to become important again in the future, as the choice of raw materials is now of great significance not only for economic reasons by influencing competitiveness, but also because this choice largely determines the properties of the derivatives produced and their ecological effects. Following the two oil crises of the 1970's, there is also now a growing awareness of the limits of raw material resources, and against the continuing background of agricultural surpluses, chemists are again showing an increasing interest in renewable raw materials. Since the end of the seventies, the Bundesministerium fur Forschung und Technologie (Ministry of Research and Technology of the Federal Republic of Germany) has supported research projects on renewable raw materials in universities and in industry. For the chemical industry the use of natural products as raw materials opens up a wider spectrum of synthetic methods and finished products, some of which are not accessible by petrochemical routes.
Effect of Reaction Temperature on Carbon Nanotubes

A series of the carbon nanotubes were synthesized on quartz substrates in a chemical vapor deposition (CVD) process. Ethylene was used as the carbon source, and ferrocene used as the catalyst. The scanning electron microscope (SEM) and Raman spectrum were employed to investigate the effects of reaction temperature on the structure and components of the carbon nanotubes. The results showed that, when the reaction temperature is 860°C , the best synthesis of the well-distributed carbon nanotubes with less of non-carbon impurity was achieved. At this condition, The length of the CNTs was 95 μm and the diameter was 104 nm.
Refractory arsenic species in estuarine waters

Total digestion of estuarine water samples by dry ashing shows that a significant fraction of dissolved arsenic does not form hydrides with sodium tetrahydroborane (NaBH4) and is therefore not detected by the normal hydride generation-atomic absorption analytical technique. It is also refractory to alkaline digestion with sodium hydroxide. Sequential ultrafiltration suggests a molecular weight below 210 for this new arsenic fraction. The magnitude and molecular weight of this fraction may open new perspectives on the biogeochemical cycling of arsenic. Ecological reasons can explain the discrepancy between these findings and previous research.