Miracle-dz/UniFAR-FTUs huggingface dataset:
Regioselective synthesis of substituted 1-thiohex-2-enopyranosides

A variety of 1-thiohex-2-enopyranosides have been prepared from their corresponding 3-O-methyl- or 3-O-acetylglycals by using trimethylsilyl thiols catalyzed by BF/sub 3/ etherate. This method is regioselective for thiolation at C-1 in contrast to the same reaction with thiols which produces C-3 products under thermodynamic control. The stereoselectivity of the reaction depended on the choice of trimethylsily thiol and the leaving group at C-3 of the glycal. ((Trimethylsilyl)thio)benzene gave . cap alpha. -anomers as the only products, whereas (thionacetoxy)trimethylsilane gave more . beta. -anomer products from 3-O-methylglycals than from 3-O-acetylglycals. Examples reported include the synthesis of S-(2'-pyridyl) 2,3,6-trideoxy-4,6-di-O-acetyl-1-thio-. cap alpha. -D-erythro-hex-2-enopyranoside (1), S-phenyl 2,3,6-trideoxy-4-O-methyl-1-thio-. cap alpha. -L-erythro-hex-2-enopyranoside (15), S-acetyl 2,3,6-trideoxy-4-O-methyl-1-thio-. beta. -L-erythro-hex-2-enopyranoside (16), S-acetyl 2,3-dideoxy-4,6-di-O-methyl-1-thio-. cap alpha. ,. beta. -D-erythro-hex-2-enopyranosides (17, 18), S-acetyl 2,3-dideoxy-4,6-di-O-acetyl-1-thio-. cap alpha. ,-. beta. -D-erythro-hex-enopyranosides (19, 20), and S-acetyl 2,3,6-trideoxy-4-O-acetyl-1-thiol-. cap alpha. ,. beta. -L-erythro-hex-2-enopyranosides (21,22). 24 references, 3 figures, 2 tables.
Layer‐structured poly(vinyl alcohol)/graphene oxide nanocomposites with improved thermal and mechanical properties

Received 6 March 2010; accepted 12 August 2010DOI 10.1002/app.33279Published online 23 November 2010 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: Layer-structured poly(vinyl alcohol)/gra-phene oxide nanocomposites in the form of films are pre-pared by simple solution processing. The structure andproperties of these nanocomposites are studied using X-raydiffractions, scanning electron microscopy, Fourier-transforminfrared spectroscopy, differential scanning calorimetry, andthermogravimetric analysis. The results indicate that gra-phene oxide is dispersed on a molecular scale and aligned inthe poly(vinyl alcohol) matrix, and there exists strong interfa-cial interactions between both components, which are re-sponsible for the significant improvement in the thermal andmechanical properties of the nanocomposites.
The Effect of Bases and Formulation on the Release of Indomethacin from Suppositories

The in vitro release characteristics of indomethacin from different suppository formulations were investigated using a dialysis method. Suppositories containing 100 mg of indomethacin were prepared by the fusion method in a variety of Witepsol and Novata bases with different hydroxyl values. The rate of release of indomethacin was found to be unexpectedly higher from oily bases with low hydroxyl values.Furthermore, the effect of surface active agents and some excipients commonly used in suppository formulations on the release properties of indomethacin was determined. Colloidal silicon dioxide, sodium lauryl sulphate and cetyl alcohol had a slight effect, on the release of indomethacin, whereas dioctyl sodium sulphosuccinate significantly increased the amount of indomethacin released. White beeswax and Tween-80, however, resulted in a marked decrease in the release of indomethacin.The in vitro release of indomethacin from five commercially available preparations was also determined using the same method.
PMMA based soluble polymeric temperature sensors based on UCST transition and solvatochromic dyes

Poly(methyl methacrylate) copolymers labeled with a UV/vis or fluorescent dye were synthesized by RAFT polymerization and subsequently investigated as optical or fluorescent temperature sensors in ethanol. The UCST transition of PMMA in combination with solvatochromic dyes was found to result in a wide linear temperature response and to provide insights into the structural conformation of the PMMA chains during the UCST phase transition.
Kinetics and mechanism of hydrolysis of 3-diazobenzofuran-2-one and its hydrolysis product (3-hydroxybenzofuran-2-one)

Rates of acid-catalyzed hydrolysis of 3-diazobenzofuran-2-one, measured in concentrated aqueous perchloric acid and hydrochloric acid solutions, were found to correlate well with the CoxYates Xo excess acidity function, giving kH+ = 1.66 × 104 M1 s1, m = 0.86 and kH+ /kD+ = 2.04. The normal direction (kH/kD > 1) of this isotope effect indicates that hydrolysis occurs by rate-determining protonation of the substrate on its diazo-carbon atom. It was found previously that the next higher homolog of the present substrate, 4-diazoisochroman-3-one, also undergoes hydrolysis by this reaction mechanism but with a rate constant 15 times greater than that for the present substrate; this difference in reactivity can be understood in terms of the various resonance forms that contribute to the structures of these substrates. The product of the present hydrolysis reaction is 3-hydroxybenzofuran-2-one, which itself quickly undergoes subsequent acid-catalyzed hydrolysis to 2-hydroxymandelic acid. The acidity depende.
Surface modification of commercial polyamide reverse osmosis membranes by radical grafting: An ATR‐FTIR study

A new grafting procedure was developed for surface modification of commercial polyamide reverse osmosis membranes. Acidic and neutral acrylic monomers and sulfo-containing vinyl monomers were successfully grafted from aqueous solutions under mild conditions. The modifications were monitored by ATR-FTIR spectra. The characteristic peaks of functional groups introduced by grafting were evaluated. The spectral findings correlated with physicochemical properties of the membranes.
Stress relaxation in transient networks of symmetric triblock styrene-isoprene-styrene copolymer

We study thermoplastic elastomers of triblock copolymers, of the form polystyrene−polyisoprene−polystyrene (SIS), where the microphase-separated PS blocks act as physical cross-links for the PI elastic network. Two compositions are examined: one with micellar cubic and the other with hexagonal cylindrical morphology of PS. Remarkably, the long-time stress relaxation is very similar; it reveals a continuous crossover between the typical response of a classical rubber at low temperatures and that of an entangled melt at high temperatures, above the Tg of polystyrene micelles. However, at a temperature T* well below the glass transition Tg(PS), the stress relaxation experiences a crossover between the classical rubber power law and a much faster relaxation above T*, which follows a stretched-exponential law for the extension modulus E(t) ∼ b exp[−(t/τ)0.2]. Time−temperature superposition is possible at all temperatures below Tg(PS), but the classical WLF equation could not be made to describe the shift fact.
Influence of Water on the Extraction of Essential Oils from a Model Herb Using Supercritical Carbon Dioxide

Extraction tests were undertaken using supercritical carbon dioxide at 100 bar and 313 K on the model herb Origanum vulgare L. ssp. virens (Hoffm. et Link) letswarrt in the presence of water. An increase in the extraction degree of essential oils was noted when water was added in either a discontinuous or a continuous manner. The largest increase was observed when water was added discontinuously at a concentration of 80% w/w. The discontinuous addition of water also led to a reduction in the yield of the coextracted waxy material. In contrast, the continuous addition of water led to an increase in the yield of waxy material. The increase in the degree of extraction of the essential oils from the plant matrix was largely due to interactions between the modifier + fluid + matrix, which was confirmed by experimental tests on an inert matrix. Vapor-phase data for the CO2 + carvacrol + water system from 80 to 320 bar at 313 K are also given.
Global methods for dynamic optimization and mixed-integer dynamic optimization

An overview of global methods for dynamic optimization and mixed-integer dynamic optimization (MIDO) is presented, with emphasis placed on the control parametrization approach. These methods consist of extending existing continuous and mixed-integer global optimization algorithms to encompass solution of problems with ODEs embedded. A prerequisite for so doing is a convexity theory for dynamic optimization as well as the ability to build valid convex relaxations for Bolza-type functionals. For solving dynamic optimization problems globally, our focus is on the use of branch-and-bound algorithms; on the other hand, MIDO problems are handled by adapting the outer-approximation algorithm originally developed for mixed-integer nonlinear problems (MINLPs) to optimization problems embedding ODEs. Each of these algorithms is thoroughly discussed and illustrated. Future directions for research are also discussed, including the recent developments of general, convex, and concave relaxations for the solutions of nonlinear ODEs.
Experimental Method to Determine the Mass Transport Resistance of a Polymer Electrolyte Fuel Cell

A technique to measure an average mass-transport resistance of a polymer electrolyte fuel cell in situ is described. Experimental polarization curve data are extrapolated to the limiting current, at which the driving force for diffusion can be accurately estimated. The technique gives very reproducible results and is sensitive to changes in the mass-transport characteristics of the cell. Using a resistance-in-series approach, the mass-transport characteristics of the electrode and gas diffusion media (GDM) can be separated. For the particular system used in this study, it is estimated that the GDM accounts for about 25% of the total mass-transport resistance of the fuel cell assembly. Bulk gas diffusion accounts for less than half of the measured mass-transport resistance. The measured mass-transport parameter may also be utilized for comparison of fuel cell systems, analysis of the effect of operating conditions, or for tracking changes during durability testing.
DIFFERENTIAL SCANNING CALORIMETRY DETECTION OF HIGH OLEIC SUNFLOWER OIL AS AN ADULTERANT IN EXTRA‐VIRGIN OLIVE OIL

Differential scanning calorimetry (DSC) was employed to detect high oleic sunflower oil (HOSo) as an adulterant in extra-virgin olive oil (EVOo) by means of cooling and heating thermograms. Addition of HOSo did not significantly alter cooling profiles of EVOo except for onset temperature of crystallization, which was significantly shifted toward lower temperature at 40% of adulterant addition. At the same percentage of adulteration, the heating profile of EVOo was significantly changed as the major endotherm broadened and the minor event became smaller and less evident. Cooling thermograms of pure oils and their admixtures were deconvoluted into three constituent exothermic peaks in an attempt to detect addition of HOSo at levels lower than 40%. Thermal properties of the two lower-temperature exotherms (area percentage, offset temperature and range of transition) were significantly changed at≥20% of HOSo substitution, suggesting that DSC can be employed to detect this oil as an EVOo adulterant. PRACTICAL APPLICATIONS Adulteration of extra-virgin olive oil (EVOo) with cheaper oils from other vegetable sources or seeds, as well as with lower quality olive oils, is a serious concern for oil suppliers and consumers and requires the use of new analytical techniques for their detection. Differential scanning calorimetry (DSC) exhibits some advantages over the classical analytical methods as it does not require sample preparation and use of solvents, thus resulting in a reduced environmental impact. Results suggested that its application to the detection of EVOo adulteration with high oleic sunflower oil, a vegetable oil largely employed for this type of fraud, is promising with the support of the deconvolution analysis of cooling thermograms.
Speeding up Monte Carlo molecular simulation by a non-conservative early rejection scheme

Monte Carlo (MC) molecular simulation describes fluid systems with rich information, and it is capable of predicting many fluid properties of engineering interest. In general, it is more accurate and representative than equations of state. On the other hand, it requires much more computational effort and simulation time. For that purpose, several techniques have been developed in order to speed up MC molecular simulations while preserving their precision. In particular, early rejection schemes are capable of reducing computational cost by reaching the rejection decision for the undesired MC trials at an earlier stage in comparison to the conventional scheme. In a recent work, we have introduced a ‘conservative’ early rejection scheme as a method to accelerate MC simulations while producing exactly the same results as the conventional algorithm. In this paper, we introduce a ‘non-conservative’ early rejection scheme, which is much faster than the conservative scheme, yet it preserves the precision of the method. The proposed scheme is tested for systems of structureless Lennard-Jones particles in both canonical and NVT-Gibbs ensembles. Numerical experiments were conducted at several thermodynamic conditions for different number of particles. Results show that at certain thermodynamic conditions, the non-conservative method is capable of doubling the speed of the MC molecular simulations in both canonical and NVT-Gibbs ensembles.
The Influence of Post-Oxidation Annealing Process in O2 and N2O on the Quality of Al/SiO2/n-Type 4H-SiC MOS Interface

The effect of the n-type 4H-SiC (0001) oxidation in wet O2 at temperature of 1175 °C followed by low temperature annealing in N2O at temperature of 800°C for 2 or 4 hours followed by high temperature annealing in nitrogen ambient on nitrogen distribution in silicon dioxide was investigated. It was shown that the oxidation and annealing have a strong impact on the behavior of electrical parameters of MOS capacitors using the oxides as gate dielectric what is probably an effect of nitrogen incorporation. The explanation of the observed electrical properties is included.
Novel Synthesis of Mercaptopurine and Pentaaza-as-Indacene Analogues: Reaction of (Bis(methylthio) methylene) malononitrile and Ethyl 2-Cyano-3,3-bis (methylthio) acrylate with 5-Aminopyrazoles.

A novel synthesis of 7-methylthiopyrazolo[1,5-a]pyrimidines via reaction of [bis(methylthio)methylene]malononitrile and ethyl 2-cyano-3,3-bis(methylthio)acrylate with 5-aminopyrazoles is reported and the synthetic potential of the method is demonstrated.
Combined Crystallization and Drying in a Pilot-Scale Spray Dryer

Combined crystallization and drying of lactose solutions was performed in a pilot-scale spray dryer over a wide range of operating conditions. The effect of different parameters, including temperature, moisture content, atomizing air flow rate, liquid feed rate, main drying air flow rate, and particle size, on the degree of crystallinity of the spray-dried powders was analyzed. Water-induced crystallization (WIC) and modulated differential scanning calorimetry (MDSC) were used to assess the effect of these parameters on the degree of crystallinity of the spray-dried powders. The particles were characterized in terms of the final moisture content using WIC and distinctive differences in the peak heights, which are indicative of the particle crystallinity, were found for spray-dried particles using different drying conditions, supporting the results from MDSC. MDSC showed that decreasing the inlet air temperature by 40°C increased the degree of crystallinity in the particles threefold from 22 to 72%. A decrease in the inlet air temperature may decrease the particle temperature, resulting in wetter particles, and a lower temperature meant a longer particle drying time and allowed the particles to rearrange themselves into a more crystalline form. Up to 72% crystallinity is achievable in a pilot-scale spray dryer by suitable adjustment of the operating conditions. The results suggest differences in the rate of crystallization and particle size between small and pilot-scale spray dryers.
Structural Control in ATRP Synthesis of Star Polymers Using the Arm-First Method

Star polymers were synthesized via atom transfer radical polymerization (ATRP) using the “arm-first” method. First, linear poly(tert-butyl acrylate) (polytBA) precursors were prepared, and subsequently divinylbenzene (DVB) was added as cross-linker at certain tBA conversion. Several experimental parameters, including the polytBA arm length, the amount of cross-linker, the monomer conversion at which DVB was added, and the chemical composition of the star core (fraction of tBA units in the star core), were systematically varied. For example, the degree of polymerization of the polytBA arm was typically 40 and was varied from 20 to 90. The molar ratio of DVB to the macroinitiator was varied from 1.5 to 15, and DVB was added at 60%, 80%, and 90% tBA conversions. The influence of these factors on the structures of the star polymers was studied. Employing shorter arm lengths and using more cross-linker produced star polymers in higher yield, with higher molecular weight, with more arms per star, and with a mor.
The kinetics of hydrolytic polymerization of ε‐caprolactam. V. Equilibrium data on cyclic oligomers

The concentrations of the cyclic oligomers (Ci; i = 3, 4, 5, and 6) in the polymeric products of e-caprolactam were determined by high-performance liquid chromatography. The equilibrium data on the oligomers were obtained as a function of the polymerization temperature and initial water concentration. The concentration of each oligomer in the equilibrated polymer was found to increase with the temperature and/or initial water concentration. A set of the kinetic equations to express the oligomer formation during the polymerization was also proposed.
Femtosecond fluorescence depletion spectroscopy of NO2 multiphoton dissociation dynamics

Two-color femtosecond pump–probe spectroscopy has been applied to the multiphoton dissociation of NO2 with a time resolution of ⩽350 fs. At laser intensities in the range ≃3×1012–2×1013 W cm−2 and a wavelength of 400 nm, NO2 absorbs three photons before dissociation. Nascent NO A 2Σ+ product in its n′=0 and 1 vibrational levels is probed by single-photon fluorescence depletion at 800 nm. Analyses of the ultrafast transient behavior at different intensities leads to an estimate of ⩽600 fs for formation of NO A 2Σ+ n′=0 and 1.
Crystal Structure, Phase Transition, and Thermodynamic Properties of Bis‐dodecylammonium Tetrachlorozincate (C12H25NH3)2ZnCl4(s)

The crystal structure and composition of (C12H25NH3)(2)ZnCl4(s) were characterized by chemical and elemental analysis. X-ray powder diffraction technique and X-ray crystallography. The lattice energy of the title compound was calculated to be U-POT=888.82 kJ.mol(-1). Low temperature heat capacities of the title compound have been measured by a precision automated adiabatic calorimeter over the temperature range from 80 to 403 K. An obvious solid to solid phase transition occurred in the heat capacity curve, and the peak temperature, molar enthalpy and molar entropy of the phase transition of the compound were determined to be T-trs=(364.02 +/- 0.03) K, Delta H-trs(m) = (77.567 +/- 0.341) kJ.mol(-1), and Delta S-trs(m)=(213.77 +/- 1.17) J.K-1.mol(-1), respectively. Experimental molar heat capacities before and after the phase transition were respectively fitted to two polynomial equations. The smoothed molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were calculated and tabulated at an interval of 5 K.
Surface selectivity in blending polyethylene-poly(ethylene glycol) block cooligomers into high-density polyethylene

Entrapment functionalization of high density polyethylene with oligo(ethylene-b-ethylene glycol) is described. This surface selective method provides the equivalent of a grafted film through a blendlike procedure. Contact angle, XPS and ATR-FTIR measurements show that the poly(ethylene glycol) (PEG) units end up primarily at the outermost layers of the film. Enhanced selectivity is observed with high molecular weight PEG.
Photometric Milk Fat Determination

Summary The theoretical consideration and practical application of a photometric procedure for milk fat determination are presented. The interfering turbidity due to casein micelles is eliminated chemically by use of a calcium chelating agent. Coherent scattering is eliminated by a fivefold dilution of milk samples. Using a favorable wave length of light, in the visible range, turbidity is measured as a function of average globule size for the size range of fat in homogenized milk. The two characteristics of the milk fat emulsion which then remain unalterably to influence the total scattering are fat content and average globule size. Two independent photometric measurements are required to solve for the two variables simultaneously. The parallel transmitted and the total transmitted light through a thin layer of the prepared sample constitute two independently variable intensities. Mathematical development of the problem led to two linear equations from which a nomogram can be constructed to read both fat content and average particle size. From photometric readings on known samples, a nomogram was drawn and the two characteristics read for a number of commercial milk samples. The results agree well with the Babcock comparative values. Applicability of the present method to other dairy products is discussed.
Preparation of zeolite A and faujasite membranes from a clear solution

Zeolite A and faujasite- (FAU-)type zeolite membranes were prepared under identical conditions from solutions of the same composition, with the only difference being the seed crystal used. The zeolite A membrane was formed on a substrate seeded with zeolite A crystals, while the FAU membrane was formed with zeolite Y seeds. The induction period of clear solution was used to prevent the influence of precipitated crystals that will eventually form in the clear solution and to keep the composition of the synthesis solution constant. Zeolite crystals increased in size with synthesis time and formed a continuous membrane on a porous substrate. Selectivity in a liquid mixture separation by pervaporation increased as crystals grew, indicating a decrease in intercrystalline region size.
Mössbauer investigation of zinc ferrite particles

Mossbauer spectra of Zn0.2Fe2. 3O4 particles at different temperatures have been obtained. They have been analyzed with five components, one due to the A‐site Fe3+ ions, and the others due to the B‐site Fe3+ and Fe2+ ions. Magnetic and electronic properties have been discussed with regard to zinc substitution and temperature dependence.