bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase Equilibria in Fluid Systems (Invited Lecture)
Authors: Schneider Gerhard M. 
Published: July 2012

AbstractThe present review considers some phase equilibrium phenomena that are important for fluid extraction, supercritical fluid chromatography (SFC) and other applications. The most important types of phase diagrams involving liquid‐gas, liquid‐liquid and gas‐gas equilibria are treated. Recent results are given for binary mixtures of a highly volatile (mostly supercritical) component 1 (e.g. CO2, N2, CHF3, SF6, propane) with a relatively involatile component 2 of very different molecular size, shape, structure and/or polarity (predominantly long‐chained and cyclic hydrocarbons); here mainly critical locus curves and pressure‐concentration isotherms are considered. Finally the determination of capacity ratios and binary diffusion coefficients from supercritical fluid chromatography (SFC) is shortly discussed and recent results are presented.
Solubility of Solids in Supercritical Solvents I. General Principles (Invited Lecture)
Authors: Koningsveld R. , Kleintjens L. A. , Diepen G. A. M. 
Published: July 2012

AbstractSolubility of solids in supercritical solvents is not essentially different from equilibrium crystallisation/solubility behaviour in normal liquids, except for the highly non‐ideal nature of nearcritical fluid mixtures. It can be shown quite generally that interactions in the fluid phase play a predominant role both at the first and the second critical endpoints in a binary system. Further factors of importance, particularly at the second critical endpoint, are the solute's heat of fusion and the location of its triplepoint compared with that of the critical point of the solvent. In the separation of two solid components ternary critical endpoint behaviour and the location of the ternary eutectic further determine the selectivity of the extraction. The mean‐field lattice‐gas model provides a useful tool to describe and predict fluid phase behaviour around critical points.
Fluid Phase Equilibria in Binary Ethylene + n‐Alkane Systems
Authors: De Loos Th. W. , Poot W. , Lichtenthaler R. N. 
Published: July 2012

AbstractVapour‐liquid equilibria in binary systems of ethylene with n‐eicosane, n‐hexacosane and n‐tetracontane have been measured in the temperature range 325 to 450 K and at pressures up to 40 MPa. The results show a distinct influence of the molecular weight of the n‐alkanes on these equilibria especially in the critical region. Except for the critical region the fluid phase equilibria in this kind of systems can be represented reasonably well using the Peng‐Robinson equation of state with temperature dependent pure component parameters a and b and two binary interaction parameters.
Variable‐Volume Circulation Apparatus for Measuring High‐Pressure Fluid‐Phase Equilibria
Authors: Radosz M. 
Published: July 2012

AbstractA new variable‐volume circulation apparatus is presented for measuring high‐pressure fluid‐phase equilibria. This apparatus was designed to handle liquid‐liquid, vapor‐liquid and vapor‐liquid‐liquid equilibria at temperatures from 10 to 260°C and pressures up to 35 MPa (5000 psia). Such versatility is useful for obtaining data for supercritical and subcritical extraction of chemicals where all these types of phase equilibria can be observed. The apparatus is an efficient and accurate engineering tool to generate equilibrium phase compositions needed to develop and design separation processes. Its capabilities are illustrated with phase equilibrium data obtained for the supercritical carbon dioxide‐isopropanol and carbon dioxide‐isopropanol‐water systems.
An Experimental Method for Measuring Solubilities of Solids in Supercritical Fluids
Authors: Kwiatkowski Jacek , Lisicki Zygmunt , Majewski Wieslaw 
Published: July 2012

AbstractAn experimental method has been developed for measuring solubilities of organic solids in supercritical fluids. These solubilities are determined by measuring the volume of gas passing through the equilibrium cell and the difference of the mass of pure solid samples placed in this cell. For mixtures of organic solids, the mass difference, the gas volume, and the composition of solid phase taken from the gas after expansion have to be determined. Special design of the equilibrium cell allowing the control of saturation has been proposed. This method has been successfully used for measuring solubilities of organic solids such as fluorene, anthracene, phenanthrene, carbazole. Solubilities of mixtures of two organic solids have also been determined.
Mass Transfer from Solid Material in Gas Extraction
Authors: Brunner G. 
Published: July 2012

AbstractExtraction rates of substances from solid substrates by supercritical gases have been determined for coffee beans and for rape oil seeds. In case of the indestructed coffee beans an unsteady extraction process prevails, which is determined by the transport of caffeine in the solid material. An approximate solution of the differential equations and a steady state approach are applicable to the long time part of the extraction process. In case of the crushed seeds a steady state mass transfer prevails which can be calculated by mass transfer calculations.
High Pressure Extraction of Crude Montan Wax
Authors: Braun Gero , Schmidt Hans 
Published: July 2012

AbstractThe high pressure extraction of crude montan wax was investigated at 20 to 100°C and at 150 to 500 bar with CO2 and ethylene and also with the fluorinated hydrocarbons Frigen 13, 13 B1 and 23. – In some cases the acid numbers, saponification numbers and setting points of the extracts differed markedly from those of the starting material. Especially at low extraction temperatures and pressures, where however solubilities are relatively low mainly low‐molecular weight wax components, such as free wax acids, wax alcohols and paraffins, as well as low‐molecular weight resin components were extracted. The corresponding high‐molecular weight components remain preferentially in the extraction residues.
New Methods for Characterization of Supercritical Fluid Solutions
Authors: Yonker C. R. , Wright B. W. , Udseth H. R. , Smith R. D. 
Published: July 2012

AbstractThe dependence of the solvating power of a supercritical fluid on pressure allows this property to be continuously changed from that of a gas to approaching that of a liquid. This ability has led to the development of new analytical, separation, and extraction methods. These methods include open tubular capillary column supercritical fluid chromatography, direct fluid injection‐mass spectrometry, and the direct combination of these techniques. The direct fluid injection process enables the transfer of nonvolatile or thermally labile compounds to the gas phase allowing the use of mass spectrometry and other analytical techniques. In addition, the rapid development of capillary column supercritical fluid chromatography now allows the high resolution separation of complex mixtures. Several examples are given to demonstrate the application of these methods for the characterization of complex supercritical fluid solutions and extracted mixtures.
The Luminescence of Bismuth Molybdates
Authors: Blasse G. , Boon L. 
Published: July 2012

AbstractThe luminescence properties of Bi2MoO6, Bi2MO2O9, and Bi2(MoO4)3 are reported. Excitation bands peak in the violet, and emission bands in the red spectral region. The results are discussed in connection with the crystal structures and compared with those of the corresponding tungstates. The luminescence of γ'‐Bi2MoO6 suggests fourfold coordination for molybdenum in the phase.
Photolumineszenz und Energietransfer im mit Seltenen Erden aktivierten Perowskit Ca2Lao,5Na0,5WO6
Authors: Otto R. , Kemmler‐Sack S. 
Published: July 2012

AbstractBy activation of the new host lattice Ca2La0.5Na0.5WO6 with trivalent rare earth ions an emission in the visible (Ln3+ = Sm, Eu, Dy, Ho, Er, Tm) or near infrared region (Nd, Ho, Er, Tm, Yb) is observed. Energy transfer from Nd3+ to Yb3+ and Er3+, Tm3+, Yb3+ to Ho3+ has been found to occur. The excitation, emission and diffuse reflectance spectra are discussed and compared to the properties of the systems Sr2La0.5Na0.5WO6: Ln3+.
A Resonance Raman Investigation on the Degradation of Polyacetylene During Electrochemical Cycling
Authors: Wieners Gerhard , Monkenbusch Michael , Wegner Gerhard 
Published: July 2012

AbstractThe degradation of a polyacetylene (PA) anode as proposed in PAy+ (ClO)y/LiClO4/PC type half cells has been investigated by resonant Raman scattering. – During electrochemical cycling, which modelled the operation of a PA/Li cell as a rechargeable storage battery, degradation becomes evident after only a few cycles. The charge regainable in the reduction steps after the seventh step is only 80 percent of the charge transferred in the preceding oxidation step. – The resonance Raman spectra have been analysed according to the method of Kuzmany which yields informations on the length distribution of conjugated segments in the sample. At the beginning of cycling a distribution of long segments and a distribution peaked at segment lengths around 5 double bonds have been found to coexist. After 7 cycles the long segments are already affected by the degradation and after a total of 27 cycles the Raman spectrum reveals the complete absence of conjugated segments longer than 10 double bonds.
Magnetic Susceptibility and Optical Absorption Studies of Rb – Au Alloys
Authors: Nicoloso N. , Freyland W. 
Published: July 2012

AbstractThe magnetic susceptibility of liquid Rb – Au alloys and the optical absorption of the solid and liquid equimolar alloy RbAu have been measured up to temperatures of 1000°C. The optical gap of solid RbAu shows Urbach type behaviour with E0 = 2.75 ± 0.1 eV. On melting it is reduced by about 1 eV: Eg(510°C) = 1.35 ± 0.1 eV. The magnetic susceptibility exhibits a strong diamagnetic minimum near the equiatomic composition yielding further evidence that liquid RbAu is semiconducting and predominantly ionic in bonding. The observed deviation from the expected susceptibility value for purely ionic RbAu and the high optical absorption in the near infrared suggest that localized paramagnetic electron states exist in the ionic liquid, possibly in equilibrium with free carriers. Like Cs – Au the alkali metal‐gold system Rb – Au thus closely resembles the alkali metal‐halogen systems the major differences arising from the reduced charge transfer and chemical ordering in these alloys.
Hydrogen Bonds in Hydrohalides of Amino Acids. A 79,81Br and 127I NQR Study
Authors: Fleck Silvia , Weiss Alarich 
Published: July 2012

AbstractBy 79,81Br− and 127I NQR the hydrobromides of glycine, l‐alanine, l‐leucine, l‐proline, semicarbazide and the hydroiodides of l‐leucine and semicarbazide were studied in the temperature range 77 ≦ T/K < decomposition point. Furthermore the compound diglycine sodium iodide monohydrate was investigated. A phase transition is observed for l‐leucine hydrobromide at 331.5 K, which is reversible and of small transition enthalpy, as shown by DTA. – 79,81Br NQR frequencies are strongly influenced by hydrogen bonds N+ – H…Br− and O – H…Br−. The 79Br frequencies can be grouped into two bands, one at 15 < ν/MHz < 19, the other at 24 < ν/MHz < 26. The high frequency group of compounds is characterized by N+ – H…Br− and O – H…Br− hydrogen bonds, whereas the bond scheme of the low frequency compounds is determined by bonds N+ – H…Br− only. This grouping of the amino acid hydrobromides according to frequency band and hydrogen bond scheme can be applied to the hydroiodides and to diglycine sodium iodide monohydrate, too.
Electron Transfer Reactions at n‐GaP (100) and (111) in Acetonitrile Solutions Facilitated by Cation Adsorption
Authors: McIntyre R. , Gerischer H. 
Published: July 2012

AbstractElectron transfer reactions occurring at n‐GaP (111) and (100) electrodes have been investigated in acetonitrile solutions. In the presence of strongly oxidising cations, such as 10‐methylphenothiazine (10‐MP+·), Ferrocene (Cp2Fe+) and tetrathiafulvalen (TTF+·), it is shown that electron transfer proceeds directly from the conduction band to cations adsorbed at the semiconductor surface. Differential capacitance and photo/dark‐current measurements have been used to identify a considerable positive shift of the flatband potential (UFB) in the presence of the oxidising cation. This phenomenon is absent in the presence of a similarly oxidising neutral species. No evidence was obtained to support the model which proposes mediated electron transfer via surface states deep in the band gap.
The Concentration Dependence of the Eutectic Enthalpy of Transition in a Binary System with Application to the System Gelatin‐Water
Authors: Borchard W. , Luft B. , Reutner P. 
Published: July 2012

AbstractExplicit formulae of general validity have been derived for the eutectic enthalpy of fusion of a binary system using the balance equations of masses and enthalpies for different coexisting phases. The formation of a compound‐like intermediate phase and the incomplete transition have been included which are essentially important for polymer solvent systems. A compound‐like intermediate phase has been stated in the system water‐gelatin at the eutectic temperature with a gelatin concentration of nearly 67% by weight. Nearly 10% of the binary phase does not transform in the concentration range from 10% to 40% weight of gelatin.
Investigation of CIDEP Effects of Hydrogen Radicals by Time Resolved ESR Spectroscopy
Authors: Beckert D. , Mehler K. 
Published: July 2012

AbstractBy means of time resolved ESR spectroscopy the CIDEP effects of hydrogen radicals produced by pulse radiolysis of aqueous solutions were investigated. The quantitative analysis of the ESR time profiles of both H atom hfs lines and of D atom hfs lines based on the modified Bloch equations allows us to determine the spin relaxation times T1 and T2, the chemical life time τH and the initial and recombination polarizations PA, PA. While the relaxation rates T and T and the reciprocal of the life time τH−1 are proportional to the H radical concentration the recombination polarization PR is independent on the H atom concentration but shows an asymmetric behaviour to the spectrum centre. This asymmetry can be attributed to the ST0‐ and ST−1‐polarization of F pairs. – The experimental polarization parameters were compared with the theoretical results obtained from the stochastic Liouville equation by Pedersen and Freed. By this comparison the following quantities can be determined:

The exchange interaction J(d) at the distance of closest approach of two H radical without recombination,
The distance d of closest approach without use of the Smoluchowski relation and
The number of radical pairs in the spur of water radiolysis including the probability of triplet and singlet precursors of direct produced H atoms in water radiolysis.
Do miRNAs have a deep evolutionary history?
Authors: Tarver James E. , Donoghue Philip C. J. , Peterson Kevin J. 
Published: July 2012

AbstractThe recent discovery of microRNAs (miRNAs) in unicellular eukaryotes, including miRNAs known previously only from animals or plants, implies that miRNAs have a deep evolutionary history among eukaryotes. This contrasts with the prevailing view that miRNAs evolved convergently in animals and plants. We re‐evaluate the evidence and find that none of the 73 plant and animal miRNAs described from protists meet the required criteria for miRNA annotation and, by implication, animals and plants did not acquire any of their respective miRNA genes from the crown ancestor of eukaryotes. Furthermore, of the 159 novel miRNAs previously identified among the seven species of unicellular protists examined, only 28 from the algae Ectocarpus and Chlamydomonas, meet the criteria for miRNA annotation. Therefore, at present only five groups of eukaryotes are known to possess miRNAs, indicating that miRNAs have evolved independently within eukaryotes through exaptation of their shared inherited RNAi machinery.
Flash Crystallization – Mechanism in the Crystallizer and Operating Behavior of the Continuous Process
Authors: Gebauer Jörn , Kaiser Raffael , Kind M. 
Published: July 2012

AbstractBeim Flash‐Kristallisationsprozess werden im Kristallisationsapparat gezielt feine Kristalle (L50,3 = 20 – 70 μm) hergestellt, damit aus diesen nach der Fest/Flüssig‐Trennung in einem formgebenden Prozessschritt (Agglomeration) Partikel in gewünschter Form und Größe hergestellt werden können. Die hier vorgestellten Untersuchungen behandeln die Wirkungsmechanismen im Kristallisator, das Betriebsverhalten des kontinuierlichen Prozesses sowie die Morphologie des erzeugten Kristallisats. Es konnten Erkenntnisse für ein weitergehendes Prozessverständnis erlangt werden. Diese sind notwendig, um den Flash‐Kristallisationsprozess aus dem Labor‐ und Pilotmaßstab in einen produktionstechnischen Maßstab übertragen zu können.
Prostate‐specific antigen screening for prostate cancer and the risk of overt metastatic disease at presentation
Authors: Scosyrev Emil , Wu Guan , Mohile Supriya , Messing Edward M. 
Published: July 2012

AbstractBACKGROUND:The objective of this study was to estimate the total number of patients who would be expected to present with metastatic (M1) prostate cancer (PC) in the modern US population in a given year if the age‐specific and race‐specific annual incidence rates of M1 PC were the same as the rates in the era before prostate‐specific antigen (PSA) testing.METHODS:The authors computed the total number of men who presented with M1 PC in the Surveillance, Epidemiology, and End Results (SEER) 9 registries area in the year 2008 (the most recent SEER year) and estimated the number of cases that would be expected to occur in this area in the year 2008 in the absence of PSA testing. The expected number was computed by multiplying each age‐race–specific average annual incidence rate from the pre‐PSA era (1983‐1985) by the number of men in the corresponding age‐race category in the year 2008 and adding the products.RESULTS:In the year 2008, the observed and expected numbers of men presenting with M1 PC in the SEER 9 registries area were 739 and 2277, respectively, with an expected‐to‐observed ratio of 3.1 (95% confidence interval, 3.0‐3.2). If this ratio was applied to the total US population in the year 2008, then the total number of men presenting with M1 PC in that year would be equal to approximately 25,000 instead of the approximately 8000 actually observed.CONCLUSIONS:If the pre‐PSA era rates were present in the modern US population, then the total number of men presenting with M1 PC would be approximately 3 times greater than the number actually observed. Cancer 2012. © 2012 American Cancer Society.
A Family of Discrete Magnetically Switchable Nanoballs
Authors: Duriska Martin B. , Neville Suzanne M. , Moubaraki Boujemaa , Murray Keith S. , Balde Chérif , Létard Jean‐François , Kepert Cameron J. , Batten Stuart R. 
Published: July 2012

AbstractThe thermal and light‐induced magnetic properties of a family of discrete magnetically switchable “nanoball” species (3 nm in diameter) is reported. The self‐assembly of these materials is accomplished by the use of the metallo building block, [Cu([Tp4‐py])(NCCH3)] ([Tp4‐py]=tris‐[3‐(4'‐pyridyl)pyrazol‐1‐yl]hydroborate), combined with a [Fe(NCX)2] (X=S, Se and BH3) species. We previously showed that the thiocyanate analogue (Fe(NCS)‐nano) undergoes a thermal and light‐induced spin crossover (SCO)—the largest such discrete SCO material reported. Now included in this family are the Se and BH3 analogues, Fe(NCSe)‐nano and Fe(NCBH3)‐nano, which show increased thermal transition temperatures (T1/2=124 K, 162 and 173 K). This variation in transition temperature over the series S<Se<BH3 results in diverse photomagnetic properties, such that the light‐induced excited spin state trapping (LIESST) effect is exhibited to varying degrees and at different temperatures by the S, Se and BH3 analogues.
Complex boron redistribution kinetics in strongly doped polycrystalline‐silicon/nitrogen‐doped‐silicon thin bi‐layers
Authors: Abadli S. , Mansour F. , Pereira E. Bedel 
Published: July 2012

AbstractWe have investigated the complex behaviour of boron (B) redistribution process via silicon thin bi‐layers interface. It concerns the instantaneous kinetics of B transfer, trapping, clustering and segregation during the thermal B activation annealing. The used silicon bi‐layers have been obtained by low pressure chemical vapor deposition (LPCVD) method at 480 °C, by using in‐situ nitrogen‐doped‐silicon (NiDoS) layer and strongly B doped polycrystalline‐silicon (P+) layer. To avoid long‐range B redistributions, thermal annealing was carried out at relatively low‐temperatures (600 °C and 700 °C) for various times ranging between 30 min and 2 h. To investigate the experimental secondary ion mass spectroscopy (SIMS) doping profiles, a redistribution model well adapted to the particular structure of two thin layers and to the effects of strong‐concentrations has been established. The good adjustment of the simulated profiles with the experimental SIMS profiles allowed a fundamental understanding about the instantaneous physical phenomena giving and disturbing the complex B redistribution profiles‐shoulders. The increasing kinetics of the B peak concentration near the bi‐layers interface is well reproduced by the established model.
Crystalline Iron Oxohalide Nanotube Pea Pods
Authors: Zimmermann Iwan , Johnsson Mats , Lidin Sven 
Published: July 2012

AbstractCompounds Fe7Sb3(PO4)3O6Cl3 and Fe7Sb3(PO4)3O6Br3 are the first iron phosphates containing SbIII. They were synthesized by chemical vapor transport reactions, and their crystal structures were characterized by single‐crystal X‐ray diffraction. The compounds are isostructural and crystallize in the orthorhombic space group Pnma. Tubular Fe7(PO4)3O6X3 units (X = Cl, Br) are linked by SbO4 groups to build up a framework. The tubular units consist of an outer part made up of [FeO5X] octahedra where the Fe atoms are arranged to resemble a nanotube. Inside the tubes there are phosphate groups, and at the very center there is a chain of face‐sharing [FeO6] octahedra.