Miracle-dz/UniFAR-FTUs huggingface dataset:
Synthesis of Monolithic Al2O3 with Well-Defined Macropores and Mesostructured Skeletons via the Sol−Gel Process Accompanied by Phase Separation

Alumina (Al2O3) monoliths with well-defined macropores and mesostructured skeletons have been synthesized via a spontaneous route from the aqueous and ethanolic solution of aluminum salts in the presence of propylene oxide and poly(ethylene oxide) (PEO). The addition of propylene oxide to the starting solution controls the gelation, whereas the addition of PEO induces the phase separation. Appropriate choice of the starting composition, by which the phase separation and gelation concur, allows the production of bicontinuous macroporous Al2O3 monoliths in large dimensions (10 × 10 × 10 mm3). The size of macropores is controlled in the range of 400 nm to 1.8 μm, depending on the PEO content in starting solutions. The dried gel is amorphous, whereas heating at temperatures above 800 °C leads to the formation of crystalline phases without spoiling the macroporous morphology; nanocrystalline γ-Al2O3 is precipitated at 800 °C, α-Al2O3 starts to form at 1000 °C, and complete transformation into α-Αl2O3 is achiev.
Heterogeneous Nucleation Rate of Calcium Carbonate Derived from Induction Period

The induction period, tind, in the process of heterogeneous nucleation of CaCO3 in aqueous CaCl2−Na2CO3 solution was investigated. The tind was measured by applying the conductivity method. Diatomaceous earth and zirconium oxide were used as foreign particles to induce heterogeneous nucleation. The experimental results showed that tind decreased with an increase in supersaturation and the solid concentration of foreign particles. The solid concentration of foreign particles had a great influence on tind at low supersaturations; however, the effect of foreign particles was negligible at high supersaturations. A novel model of tind for the heterogeneous nucleation was derived by using the Michaelis−Menten equation. In this model, the heterogeneous nucleation rate, Jh, was considered to be the sum of the bulk nucleation rate, Jb, and the particle-induced nucleation rate, Jp, where Jb and Jp were contributed from the bulk of solution and the surface of added foreign particles, respectively. The results showed.
New Plasma Techniques for Polymer Surface Modification with Monotype Functional Groups

The production of chemically-defined plasma polymers and the introduction of monotype functional groups onto polymer surfaces are described. One method is to lower the energetic level of low-pressure plasmas. Pressure- and plasma-pulsed plasmas were successfully tested for the production of chemically-defined plasma polymers by increasing the monomer supply during the plasma-off period. Well-defined ultra-thin polymer films with regular structure were deposited from atmospheric plasmas by electrospray techniques. Post-plasma wet-chemical processing was also applied, as were gas/liquid-based aerosols and underwater plasmas.
Chain Transfer Activity of ω-Unsaturated Methyl Methacrylate Oligomers

The chain transfer activities of a series of ω-unsaturated methyl methacrylate oligomers [(dimer (1), trimer (2), tetramer (3), and a methyl methacrylate macromonomer with average chain length of 24 units (4)] have been evaluated in methyl methacrylate polymerizations over the temperature range 45−100 °C. Transfer constants were determined by analysis of the ln chain length distributions. The dimer (1) was found to be substantially less effective as a chain transfer agent than the trimer (2) or the higher macromonomers (3, 4) [CT(60 °C) 1, 0.013; 2, 0.19; 3, 0.31; 4, 0.21]. The transfer constants show only a small temperature dependence and no variation with conversion. No discernible retardation was observed in these polymerizations. A reduced yield of polymer observed at conversions >10% in bulk polymerizations of MMA carried out in the presence of 1−4 can be attributed to the absence of the gel (Trommsdorff) effect. The results are interpreted in terms of the addition−fragmentation mechanism for chain .
Synthesis and Characterization of Flower-Shaped Porous Au−Pd Alloy Nanoparticles

A facile synthesis of flower-shaped porous Au−Pd alloy nanoparticles with ascorbic acid as a reductant and PVP as a stabilizing agent is presented. The alloy nanoparticles were prepared from the aqueous solutions of HAuCl4/K2PdCl4 mixtures in molar ratios of 3:1, 1:1, and 1:3. The size, structure, optical properties, and composition distribution of the synthesized Au−Pd alloy nanoparticles were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, UV−vis spectroscopy, and X-ray diffraction. The experimental results for the bimetallic systems and the physical mixtures of individual monometallic nanoparticles revealed that unstable small nanoparticles aggregate into the three-dimensional flower-shaped nanoparticles and the prepared nanoparticles are Au−Pd alloys. The surfaces of Au−Pd alloy nanoparticles were characterized by cyclic voltammetry measurement in 0.1 M HClO4 and surface-enhanced Raman scattering spectra of 1,4-phenylene diisocyanide adsorbed thereon. All alloy.
Characterization of the Mn Oxidation States in Photosystem II by Kβ X-ray Fluorescence Spectroscopy

The nature of the Mn oxidation states involved in photosynthetic oxygen evolution has remained controversial, despite intense study by X-ray absorption and electron paramagnetic resonance spectroscopy. As an alternative approach, high-resolution Kβ X-ray fluorescence spectra have been recorded on the dark-adapted S1 state and the hydroquinone-reduced state of the oxygen-evolving complex in photosystem II. By comparison of the Kβ chemical shifts with those of appropriate model compounds, the S1 state of photosystem II is found to contain equal amounts of Mn(III) and Mn(IV). In the hydroquinone-reduced sample, a significant fraction of the Mn is reduced to Mn(II). The results are compatible with models involving conversion of Mn(III)2Mn(IV)2 to Mn(II)2Mn(IV)2 clusters.
Review of Analytical Methods for Identification and Determination of Triptans

A review of analytical methods for identification and determination of triptans which are a group of tryptamine based drugs used in the acute treatment of migraine headaches is presented. In this review article, various methods used for determination of triptans have been covered. The methods have been divided into four groups accordingly to the applied analytical techniques: chromatographic, electrochemical, spectrometric, and capillary electrophoretic.
Demixing of Mixed Micelles. Thermodynamics of Sodium Perfluorooctanoate−Sodium Dodecanoate Mixtures in Water

Conductivity, density, heat capacity, enthalpy of dilution, and osmotic coefficient measurements of water−sodium perfluorooctanoate (NaPFO)−sodium dodecanoate systems were carried out as functions of the surfactants' total molality (mt) at different mole fractions (XNaPFO). From conductivity data, the critical micelle concentration (cmc) and the degree of ionization (β) of the micelles were derived. The cmc's of the micelles are higher than those of the pure surfactants while β depends linearly on XNaPFO. At a given mole fraction, the apparent molar volume (VΦ) and heat capacity (CΦ) of the mixture increases and decreases monotonically with mt, respectively. From data in the premicellar region, the standard (infinite dilution) partial molar properties (Yo) of the mixtures were calculated for both volume and heat capacity. Yo depends linearly on XNaPFO according to the ideal behavior. From data in the postmicellar region, the excess properties (Yexc) for the mixed micelles formation from pure micelles were.
Thermally induced magnetization reversal in antiferromagnetically coupled media

The calculation of energy barriers between stable equilibrium states in strongly interacting systems requires the calculation of saddle points in high dimensional energy landscapes. We combine the nudged elastic band method with finite element micromagnetics to calculate optimal paths, giving a global view of thermal switching in antiferromagnetically coupled media. Energy barriers and transition rates can be estimated from the saddle points and the energy minima along this path. We investigate the dependence of the energy barrier on the strength of the antiferromagnetic coupling and study the reversal in the data bit transition region. Below 1.1 mJ/m2 a two step reversal occurs passing a metastable state. Above 1.1 mJ/m2 this metastable state disappears and the energy barrier is constant for a coupling strength greater than 1.5 mJ/m2.
Theory of Fourier transform ion cyclotron resonance mass spectroscopy: Response to frequency‐sweep excitation

Although all previous theoretical treatments of Fourier transform ion cyclotron resonance (FT–ICR) spectral line shape have been based on the ICR time‐domain response to fixed‐frequency pulsed excitation, experimental FT–ICR signals are produced by frequency‐sweep excitation. This paper presents the first analysis of the FT–ICR line shape resulting from frequency‐sweep excitation, including the effects of circularly polarized versus linearly polarized exciting radiation, continuous versus stepwise variation in swept frequency, variation in sweep parameters (e.g., frequency range, sweep rate, size of step, and number of steps), phase conventions, reliability of fast Fourier transform data reduction, and time delay between excitation and detection. In addition, we show how the nonlinear amplitude and phase variation of an FT–ICR spectrum obtained by direct Fourier transformation of a time‐domain ICR response can be corrected by deconvoluting the response with the frequency‐sweep excitation. Implementation o.
Liquid repellent nanocomposites obtained from one-step water-based spray

Significant research efforts have been directed towards the development of novel superhydrophobic and superoleophobic coatings. However, it is still highly challenging to develop facile and environmentally friendly methods that lead to surfaces and coatings with efficient liquid repellency. Herein, we demonstrate for the first time, a one-step water-based spray method on heated metallic substrates for the preparation of water and oil repellent polymer nanocomposite coatings by using hydrophilic silica nanoparticles. These environmentally-friendly coatings exhibit static contact angles exceeding 150° and roll off angles less than 5° for both water and oil and can also successfully repel a wide variety of other liquids. The influence of the chemical composition and the surface texture on the wetting properties are discussed based on measurements from white light interferometry, electron microscopy and X-ray photoelectron spectroscopy. When the substrates were treated with an adhesive primer, the wear abrasion resistance of the coatings was enhanced. The effect of silica nanoparticle dispersion in the coatings on wear abrasion is also investigated. Certain nanocomposites were found to exhibit good abrasion resistance by retaining their water repellency for up to 60 abrasion cycles under 20.5 kPa applied pressure.
Cottonised flax fibres vs. cotton fibres: structural, textural and adsorption characteristics

Structural (crystallinity), textural (pore volume, Vp, specific surface area, SBET, pore size distribution, PSD) and adsorption characteristics of bleached flax fibres and cotton fibres have been determined using equilibrium adsorption of nitrogen, water, chlorhexidine diacetate (CHX) and methylene blue (MB), adsorption–desorption kinetics of MB and CHX, X-ray diffraction, infrared spectroscopy, thermogravimetry, differential scanning calorimetry (DSC) and DSC cryoporometry. Air-dry, degassed, wetted (RH ≈ 95%), swollen (24 h in water) and air-dried and heated (120 °C for 1 h) fibres were studied. Flax fibres have higher crystallinity, adsorption capacity (MB, CHX, water), and smaller MB desorption than cotton fibres. Cotton fibres have larger Vp value (nitrogen adsorption) and the SBET,N2 similar to that of flax. Water vapour adsorption is higher on flax since the adsorbed water volume is Vp,w = 0.19 and 0.14 cm3 g−1 for flax and cotton, respectively, at RH ≈ 95%. Wetted fibres are characterised by Vp,w larger by an order of magnitude than Vp,N2 for degassed samples because of swelling effect. However, nanopores at radius R < 1 nm are practically absent in all samples studied regardless of the characterisation technique. The adsorption of MB and CHX on flax fibres is much larger than that for cotton fibres. The specific surface area determined from MB adsorption is 51 m2 g−1 (close to SBET,w estimated from water adsorption but larger than SBET,N2) and 8 m2 g−1 (much smaller than SBET,N2 and SBET,w) for flax and cotton fibres, respectively.
Cross-linking reactions during coal conversion

During coal conversion, the breakup of the coal macromolecular network and resulting product formation are controlled by the relative rates of bond breaking, cross-linking, and mass transport. THe objective of this work was to systematically study the variations in cross-linking with several parameters (rank, temperature, heating rate, pretreatment, etc.), to identify the factors that control cross-linking rates. This paper describes a study of cross-linking behavior in which chars of a number of coals (including the Argonne premium coal samples) have been pyrolyzed under a variety of temperature histories and analyzed at intermediate extents of pyrolysis for solvent swelling behavior and functionnal group compositions
Heat Transfer Enhancement by EHD-Induced Oscillatory Flows

Prior numerical solutions of electrohydrodynamic (EHD) gas flows in a horizontal channel with a positive-corona discharged wire have revealed the existence of steady-periodic flows. It is speculated that heat transfer by forced convection may be greatly enhanced by taking advantage of this oscillatory flow phenomenon induced by electric field. To verify this speculation, computations have been performed for flows with Reynolds numbers varying from 0 to 4800 and the dimensionless EHD number (which signifies the effect of electric field) ranging from 0.06 to ∞. The results show that heat transfer enhancement increases with the applied voltage. For a given electric field, oscillation in the flow and temperature fields occurs at small Reynolds numbers. Due to the presence of oscillatory secondary flows, there is a significant enhancement in heat transfer.Copyright © 2005 by ASME
Validation of Protein Structure from Anisotropic Carbonyl Chemical Shifts in a Dilute Liquid Crystalline Phase

The change in chemical shift ( ∆δ) observed for a given nucleus, when shifting from an isotropic medium to a strongly oriented, liquid crystalline phase, contains valuable information on the orientation of its chemical shift anisotropy (CSA) tensor relative to the molecular alignment tensor. 1 Analogously, we have demonstrated 2 a dramatic improvement in the agreement between observed and predicted magnetic field dependence of 15N chemical shifts in a very weakly, magnetically aligned protein -DNA complex upon inclusion of dipolar coupling constraints in the structure calculation. 3 In that case, the minute changes in 15N shift and the very small one-bond 15N-1H and13CR-1HR dipolar couplings resulted from the field-dependent degree of molecular alignment, 3 induced by the magnetic susceptibility anisotropy of the complex. 4 Use of a dilute liquid crystalline medium consisting of phospholipid bicelles 1,5 makes it possible to obtain much higher degrees of molecular alignment while nevertheless retaining the spectral simplicity of the regular isotropic phase. 6 As we show here, it is straightforward to measure the difference in chemical shift frequency when switching from the liquid crystalline to the isotropic phase. The change is largest and most easily measured for backbone carbonyl atoms. The ∆δ13C′ values can either be used as constraints in the structure calculation or to evaluate the quality of the structure. This latter application is illustrated here, using the protein ubiquitin as a test case. The change in chemical shift for a given atom upon switching from the liquid crystalline to the isotropic phase is given by
Theoretical study of electrolyte gate AlGaN/GaN field effect transistors

We predict the sensitivity of solution gate AlGaN∕GaN field effect transistors to pH values of the electrolyte and to charged adsorbates at the semiconductor–electrolyte interface. Invoking the site-binding model for the chemical reactions at the oxidic semiconductor–electrolyte interface and taking into account the large polarization fields within the nitride heterostructure, the spatial charge and potential distribution have been calculated self-consistently both in the semiconductor and the electrolyte. In addition, the source–drain current is calculated and its sensitivity to the electrolyte’s pH value is studied systematically. Comparison with experiment shows good agreement. A significantly enhanced resolution is predicted for AlGaN∕GaN structures of N-face polarity.
Facilitating the CVD synthesis of seamless double-walled carbon nanotubes

In this contribution we present a simple laser assisted chemical vapour (LA-CVD) technique that rapidly determines if a given catalyst and feedstock combination are appropriate for the bulk synthesis of double-walled carbon nanotubes (DWCNT) in conventional thermal CVD (T-CVD). Systematic T-CVD studies across a range of temperatures with a Fe–Co catalyst mix for two carbon feedstocks (ethanol and methane) were conducted to validate the LA-CVD technique. The T-CVD findings confirm that the LA-CVD route is appropriate as a fast and easy means to determine the primary carbon nanotube product for a selected catalyst and feedstock in T-CVD. The LA-CVD route reduces the optimization parameters in T-CVD to only that of temperature. The studies led to the bulk production of seamless DWCNT with yields better than 55%.
Bridged Polystannoxane : A New Route toward Nanoporous Tin Dioxide

Hydrolysis and condensation under acidic conditions of bis(triprop-l-ynylstannyl)p-phenylene 1, p-xylene 2, or butylene 3 precursors yielded bridged polystannoxanes in the form of xerogels after being dried under reduced pressure. The gels were amorphous and nonporous with very low specific surface areas. Thermal treatment of the xerogels in air at 400-500 °C resulted in nanocrystalline nanoporous cassiterite tin dioxide materials, which have been thoroughly characterized by elemental analysis, FTIR, TGA-MS, powder XRD, and N 2 adsorption porosimetry. The calcined materials consisted of a porous network of aggregated nanoparticles with a nanoporosity stemming from the interparticle space. A careful tuning of the precursor nature and the calcination conditions enabled the synthesis of materials with Brunauer-Emmet-Teller surface areas ranging from 40 to 150 m 2 g -1 , a mean pore size between 3.5 and 12 nm, and an average particle size of 5 to 25 nm. Starting from precursor 1 appeared to be the best strategy to obtain pure nanocrystalline tin dioxide materials with good textural properties for applications, with the p-phenylene bridge being easily removed by calcination.
On the role of hydrodynamic interactions in block copolymer microphase separation

A melt of linear diblock copolymers (AnBm) can form a diverse range of microphase separated structures. The detailed morphology of the microstructure depends on the length of the polymer blocks An and Bm and their mutual solubility. In this paper, the role of hydrodynamic forces in microphase formation is studied. The microphase separation of block copolymer melts is simulated using two continuum methods: dissipative particle dynamics (DPD) and Brownian dynamics (BD). Although both methods produce the correct equilibrium distribution of polymer chains, the BD simulation does not include hydrodynamic interactions, whereas the DPD method correctly simulates the (compressible) Navier Stokes behavior of the melt. To quantify the mesophase structure, we introduce a new order parameter that goes beyond the usual local segregation parameter and is sensitive to the morphology of the system. In the DPD simulation, a melt of asymmetric block copolymers rapidly evolves towards the hexagonal structure that is predict.
Linear TACN-based cationic polymers as non-viral gene vectors

A series of linear cationic polymers were synthesized by the ring-opening polymerization between diglycidyl ethers and 1-Cbz-1,4,7-triazacyclononane (TACN). Besides the good pH buffering capacity in endosome pH range caused by TACN, these polymers have evenly distributed hydroxyl groups, which may benefit not only the water solubility but also their biocompatibility and serum tolerance. The polymers could condense DNA into nanoparticles with appropriate sizes and zeta-potentials. Cytotoxicity assays reveal that most of the polyplexes formed from title polymers have lower cytotoxicity than those derived from PEI. In vitro transfection assays show that some of these materials have higher transfection efficiency than bPEI, especially in tumor cells with the presence of serum. Flow cytometry and confocal microscopy were applied to further confirm their good serum tolerance. The structure–activity relationship of such type of polymeric vectors was also discussed. Results suggest that the ring-opening polymerization may be an effective synthetic approach toward gene delivery materials with high biological activity.
Synthesis and Characterization of Castor Oil/Trimethylol Propane Polyol as Raw Materials for Polyurethanes Using Time-of-Flight Mass Spectroscopy

Abstract Recognizing the worldwide tendency towards biodegradable products, trimethylol propane (TMP) esters based on castor oil (CO) were synthesized, composition and properties were evaluated, and their potential as raw material for polyurethane preparation was assessed. The method of matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI TOF MS) and atmospheric pressure chemical ionization (APCI) under positive ion mode by the method of direct injection were used to determine the components of castor oil trimethylol alcoholysis product. Both the methods allowed unambiguous molecular mass determination of the intact ester molecules without any thermal degradation. The product was found to contain in the greatest amount monoricinoleate of TMP, diricinoleate of TMP, and triricinoleate of TMP and some quantity of triricinoleate of glycerol and unreacted trimethylol propane. APCI of the polyol was compared to that of castor oil. The MALDI TOF MS method described in this work is relatively simple, less time-consuming than the commonly used gas chromatographic method, and can be used to quantify various components of the polyol.
On-line removal of interferences in the analysis of biological materials by flow injection inductively coupled plasma mass spectrometry

A method of matrix elimination was developed that facilitates the interference-free determination of the trace metals vanadium, manganese, copper, zinc, cadmium and lead in biological matrices by inductively coupled plasma mass spectrometry. The method involves chelation of the analytes onto an iminodiacetate-based resin in a microcolumn with simultaneous matrix removal. The analytes are then eluted into the spectrometer with 3 mol l–1 nitric acid using a flow injection procedure. Analysis of certified reference materials yielded results in reasonable agreement with the certified values. Recovery tests showed close to 100% recoveries for manganese, copper, cadmium and lead, 90% recovery for vanadium and 85% recovery for zinc. The limit of detection (3σ) for these analytes using a 175 µl sample loop ranged from 0.6 to 9.9 ng ml–1i.e. , from 75 to 1800 pg or from 50 to 825 µg kg–1 dry mass of sample. The same chromatographic system was applied to chromium determinations, but proved unsuccessful.