Wilhelm Ostwald’s energetics 3: energetic theory and applications,part II

This is the third of a series of essays on the development and reception of Wilhelm Ostwald’s energetics. The first essay described the chemical origins of Ostwald’s interest in the energy concept and his motivations for seeking a comprehensive science of energy. The second essay and the present one discuss his various attempts, beginning in 1891 and extending over almost 3 years, to develop a consistent and coherent energetic theory. A final essay will consider reactions to this work and Ostwald’s replies, and will also seek to evaluate his program of research. Ostwald’s project—to reconstruct physics and chemistry “as a pure energetics”—is worth attending to for several reasons: first, because Ostwald did ground-breaking work in chemistry (he was awarded a Nobel Prize in 1909 for his studies in catalysis and rates of reaction); second, because an important school of physical chemistry formed around him at Leipzig, a school that promoted his ideas; and, finally, because he was a prominent and vigorous participant in debates at the end of the nineteenth century concerning the proper course of physical theory.

The interaction energy between identical particles

The improved Derjaguin’s method is used to derive the approximate expressions for the electrostatic interaction energy between spherical colloidal particles. The approximate results are in good agreement with the exact numerical solutions. The results from the product of the original Derjaguin approximation with curvature correction 2a/R can be used satisfactorily at different αa and κh, no matter high or low the potential of spherical particle is. The text was submitted by the authors in English.     

A new form of MgTa2O6 obtained by the molten salt method

Using molten salt route (with NaCl/KCl as the salt) we have been able to synthesize a new form of magnesium tantalate at 850°C. Powder X-ray diffraction data could be inde_xed on an orthorhombic unit cell with lattice parameters, ‘a’ = 15.36(1) ?, ‘b’ = 13.38(1) ? and ‘c’ = 12.10(1) ?. High resolution transmission electron microscopy and electron diffraction studies confirm the results obtained by X-ray studies. Energy dispersive X-ray spectroscopy helps ascertain the composition of MgTa₂O₆. The title compound shows a dielectric constant of ∼24 with a low dielectric loss of 0.006 at 100 kHz at room temperature. Dielectric constant is nearly unchanged with rise in temperature while the loss shows a very marginal increase (0.007 at 300°C). Dedicated to Prof J Gopalakrishnan on his 62nd birthday.     

Chain “stationary” insertion mechanism and production of isotactic polypropylene with C 1 symmetric catalyst systems

In this contribution, the stereochemistry of propylene insertion/propagation reactions with a variety of C ₁ symmetric metallocene catalysts, containing bridged cyclopentadienyl-fluorenyl ligand for the preparation of highly stereoregular polypropylene is presented. The impact of the distal substitutent’s size and composition and changes that the catalytic sites undergo upon such substitution is elaborated. A comprehensive mechanism is proposed to explain the resulting catalytic changes that bring about the irreversible C _s/C ₁ site transformation and tactic behavior inversion. Furthermore the cyclopentadienyl’s combined distal/proximal and fluorenyl’s frontal substituent effects on molecular weight, regio-, and stereoregularity of the final polymers are discussed. Finally, stereoselectivities of C ₂ and C ₁ symmetric catalyst systems are compared. It is shown that current high performance C ₁ symmetric catalyst systems with central site chirality can be isotactic selective as well or even better in certain aspects than the C ₂ symmetric bridged bisindenyl-based metallocene catalysts. The text was submitted by the authors in English.     

Heat-gradient analytical technique for the simultaneous determination of some aromatic amines

A new sensitive analytical technique has been developed for the simultaneous determination of aromatic amines (aniline, p-nitroaniline, m-nitroaniline, o-nitroaniline, 1,3-phenylenediamine, and 1,4-phenylenediamine). It is based on the differential migration of colored derivatives formed by the reaction of diazotized amines with 8-hydroxy quinoline 5-sulphonic acid (FERRON) on a silica gel plate. Quantitative evaluation of amines is made by visual comparison of the intensities of color by spectrophotometry. The Beer’s law, molar absorptivity, and Sandell’s sensitivity have been determined. The effect of the analytical parameters on the migration and analysis have been evaluated. The method is highly reproducible and has been applied to the determination of amines in environmental samples. The text was submitted by the authors in English.     

Rearrangement Pathways of the <Emphasis Type="BoldItalic">a</Emphasis><Subscript><Emphasis Type="BoldItalic">4</Emphasis></Subscript> Ion of Protonated YGGFL Characterized by IR Spectroscopy and Modeling

The structure of the a ₄ ion from protonated YGGFL was studied in a quadrupole ion trap mass spectrometer by ‘action’ infrared spectroscopy in the 1000–2000 cm^–1 (‘fingerprint’) range using the CLIO Free Electron Laser. The potential energy surface (PES) of this ion was characterized by detailed molecular dynamics scans and density functional theory calculations exploring a large number of isomers and protonation sites. IR and theory indicate the a ₄ ion population is primarily populated by the rearranged, linear structure proposed recently (Bythell et al., J. Am. Chem. Soc. 2010, 132, 14766). This structure contains an imine group at the N- terminus and an amide group –CO–NH₂ at the C-terminus. Our data also indicate that the originally proposed N-terminally protonated linear structure and macrocyclic structures (Polfer et al., J. Am. Chem. Soc. 2007, 129, 5887) are also present as minor populations. The clear differences between the present and previous IR spectra are discussed in detail. This mixture of gas-phase structures is also in agreement with the ion mobility spectrum published by Clemmer and co-workers recently (J. Phys. Chem. A 2008, 112, 1286). Additionally, the calculated cross-sections for the rearranged structures indicate these correspond to the most abundant (and previously unassigned) feature in Clemmer’s work.     

Constraints for hierarchies of many electron distribution functions

Some inequalities that constrain the reconstruction of k-electron distribution functions from lower-order distribution functions are presented. These inequalities are related to the N-representability conditions on electron distributions functions and they have two basic types: (1) general N-representability inequalities, which are very powerful but difficult to apply and (2) generalized “Davidson” inequalities, which are less powerful but which may be more facile in computational implementations. A constraint on the exchange-correlation hole is also presented.     

Thermodynamic and transport properties for binary and ternary mixtures of 2-methyltetrahydrofuran?+?chlorobenzene?+?cyclopentanone at T?=?298.15?K

Abstract  

Experimental densities ρ, viscosities η, and refractive indices n _D of the ternary mixtures consisting of 2-methyltetrahydrofuran + chlorobenzene + cyclopentanone and constituted binary mixtures were measured at T = 298.15 K for the liquid region and at ambient pressure for the whole composition range. Excess molar volumes V_\textm^\textEV_{\text{m}}^{\text{E}}, deviations in the viscosity Δη, and deviations in the refractive index Δn _D from the mole fraction average for the mixtures were derived from the experimental data. The excess partial molar volumes V_\textm,i^\textEV_{{\text{m}},i}^{\text{E}} were also calculated. The binary and ternary data of V_\textm^\textEV_{\text{m}}^{\text{E}}, Δη, and Δn _D were correlated as a function of the mole fraction by using the Redlich–Kister and the Cibulka equations, respectively. McAllister’s three-body interaction model is used for correlating the kinematic viscosity of binary mixtures with the mole fraction.     

Synthesis of chiral 5-aryltetrahydrofuran-2-ones via yeast bioreduction of γ-keto acids and their esters

Enantioselective reduction of γ-keto acids and related γ-keto esters with Saccharomyces cerevisiae (baker’s yeast) leads to the formation of the corresponding chiral 5-aryltetrahydrofuran-2-ones in satisfactory chemical and optical yields. Published in Zhurnal Organicheskoi Khimii, 2006, Vol. 42, No. 3, pp. 379–382. The text was submitted by the authors in English.     

Non-protein amino acids in peptide design

An overview of the use of non-protein amino acids in the design of conformationally well-defined peptides, based on work from the author’s laboratory, is discussed. The crystal structures of several designed oligopeptides illustrate the useα-aminoisobutyric acid (Aib) in the construction of helices, D-amino acids in the design of helix termination segments and^DPro-Xxx segments for nucleating ofβ-hairpin structures.β- andγ-amino acid residues have been used to expand the range of designed polypeptide structures. Dedicated to Professor C N R Rao on his 70th birthday     

Low-temperature Data for Carbon Dioxide

Summary. We investigated empirical data for the vapor pressure (154≤T≤196 K) and the heat capacity (12.52≤T≤189.78 K) of solid carbon dioxide. A computer algebra system (CAS) was used for all calculations. From the numerical point of view, we have adopted a cubic piecewise polynomial representation for the heat capacity and reached an excellent agreement between the available empirical data and the calculated ones. Furthermore, we have obtained values for the vapor pressure and heat of sublimation at temperatures below 195 right down to 0 K. The theoretical key prerequisites are: 1) Determination of the heat of sublimation of 26250 J · mol⁻¹ at vanishing temperature and 2) Elaboration of a ‘linearized’ vapor pressure equation that includes all the relevant properties of the gaseous and solid phases. It is shown that: 1) The empirical vapor pressure equation derived by Giauque & Egan remains valid below the assumed lower limit of 154 K (a similar argument holds for Antoine’s equation), 2) The heat of sublimation reaches its maximum value of 27211 J · mol⁻¹ at 58.829 K and 3) The vapor behaves as a (polyatomic) ideal gas even for temperatures below 150 K.     

Low-temperature Data for Carbon Dioxide

We investigated empirical data for the vapor pressure (154≤T≤196 K) and the heat capacity (12.52≤T≤189.78 K) of solid carbon dioxide. A computer algebra system (CAS) was used for all calculations. From the numerical point of view, we have adopted a cubic piecewise polynomial representation for the heat capacity and reached an excellent agreement between the available empirical data and the calculated ones. Furthermore, we have obtained values for the vapor pressure and heat of sublimation at temperatures below 195 right down to 0 K. The theoretical key prerequisites are: 1) Determination of the heat of sublimation of 26250 J · mol⁻¹ at vanishing temperature and 2) Elaboration of a ‘linearized’ vapor pressure equation that includes all the relevant properties of the gaseous and solid phases. It is shown that: 1) The empirical vapor pressure equation derived by Giauque & Egan remains valid below the assumed lower limit of 154 K (a similar argument holds for Antoine’s equation), 2) The heat of sublimation reaches its maximum value of 27211 J · mol⁻¹ at 58.829 K and 3) The vapor behaves as a (polyatomic) ideal gas even for temperatures below 150 K.     

Molecular aspects of milk allergens and their role in clinical events

Milk allergy is the most frequent food allergy in childhood. Even though cases of newly developed milk allergy in adulthood are known, this allergy is less frequent in adults since it is normally outgrown by children during the first years of life. One of the reasons why allergy to cow’s milk shows its highest prevalence in children is its early introduction into the diets of babies when breast feeding is not possible. The major allergens are caseins and β-lactoglobulin, but allergies to other minor proteins (immunoglobulins, bovine serum albumin) have also been reported. Milk allergenicity can be reduced by various treatments (mainly hydrolysis), meaning that formulas based on cow’s milk can often be safely fed to children allergic to milk proteins. Cross-reactivity has been described between different mammalian milks and between milk and meat or animal dander. Cross-contamination can result from inadequate cleaning of industrial equipment and constitutes a hidden danger for allergic subjects who unknowingly ingest milk proteins. Figure Involvement (expressed as percentage of total subjects) of the most abundant milk proteins in the sensitization of 80 children allergic to cow’s milk. The upper panel includes all positive responses, even minor ones; data in the lower panel are restricted to the most severe positive responses (see text for details). SPT, skin prick test; CAP, CAP test; IMM, immunoblotting; alpha-LA, α-lactalbumin; beta-LG, β-lactoglobulin; cas, caseins; BSA, bovine serum albumin     

A century on from Dmitrii Mendeleev: tables and spirals,noble gases and Nobel prizes

Mendeleev’s failure to represent the periodic system as a continuum may have hidden from him the space for the noble gases. A spiral format might have revealed the significance of the wide gaps in atomic mass between his rows. Tables overemphasize the division of the sequence into ‘periods’ and blocks. Not only do spirals express the continuity; in addition they are more attractive visually. They also facilitate a new placing for hydrogen and the introduction of an ‘element of atomic number zero’.

A molecular based scale for solvent basicity

The charge distribution on isolated polar molecules has been determined in the gas phase on the basis of the natural bond order (NBO) analysis. It is shown that the fractional negative charge on the heteroatom or atoms associated with solvent basicity is linearly correlated to popular empirical measures of this parameter in the liquid phase, namely, the solvent’s donor number, DN, and its solvatochromic basicity B _SC. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 1, pp. 32–38. The text was submitted by the authors in English.     

The Solubility of the Chloromethanes in Water

Summary.  There are more than 150 papers that report on the solubility of the four chloromethanes in water. Volume 62 of the Solubility Data Series compiles and evaluates the papers concerned with the liquid–liquid solubility of the chloromethanes with water. A similar evaluation has not been carried out for the vapor–liquid solubility at a partial pressure up to the saturation vapor pressure of the four chloromethanes. This paper uses the liquid–liquid evaluated solubility values to calculate vapor–liquid Henry’s constants. They are compared with a compilation of Henry’s constants with good agreements between the calculated constants and the median of the compiled constants. It is believed that the calculated constants are a reliable set of values to use for the vapor–liquid solubility of the chloromethanes in water. E-mail: hlclever@worldnet.att.net Received October 11, 2002; accepted October 22, 2002 Published online April 24, 2003 RID="a" ID="a" Dedicated to Prof. Dr. Heinz Gamsj?ger on the occasion of his 70^th birthday     

Properties and performance of BaxSr1−xCo0.8Fe0.2O3−δ materials for oxygen transport membranes

The present paper discusses the oxygen transport properties, oxygen stoichiometry, phase stability, and chemical and mechanical stability of the perovskites (BSCF) and (SCF) for air separation applications. The low oxygen conductive brownmillerite phase in SCF is characterized using in-situ neutron diffraction, thermographic analysis and temperature programmed desorption but this phase is not present for BSCF under the conditions studied. Although both materials show oxygen fluxes well above 10 ml/cm²·min at T=1,273 K and pO₂=1 bar for self-supporting, 200 μm-thick membranes, BSCF is preferred as a membrane material due to its phase stability. However, BSCF’s long-term stable performance remains to be confirmed. The deviation from ideal oxygen stoichiometry for both materials is high: δ>0.6. The thermal expansion coefficients of BSCF and SCF are 24×10⁻⁶ and 30×10⁻⁶ K⁻¹, respectively, as determined from neutron diffraction data. The phenomenon of kinetic demixing has been observed at pO₂<10⁻⁵ bar, resulting in roughening of the surface and enrichment with alkaline earth metals. Stress–strain curves were determined and indicated creep behavior that induces undesired ductility at T=1,073 K for SCF. Remedies for mechanical and chemical instabilities are discussed.     

J. J. Thomson and The Electron: 1897–1899 An Introduction

Three Seminal Papers of J. J. Thomson This being the 100th anniversary of J. J. Thomsons discovery of the electron, the October 1897 paper in which he presented his case that cathode rays are streams of subatomic corpuscles is attracting a great deal of attention. Viewed from 100 years later, this paper stands out as the starting point for the research into the structure of the atom that has dominated 20th-century science. Viewed in its original historical context, however, this paper was but one of a group by Thomson and his Cavendish Laboratory research students and is matched in importance by his two ensuing papers: On the Charge of Electricity carried by the Ions produced by Röntgen Rays published in December 1898 and On the Masses of the Ions in Gases at Low Pressures published in December 1899. All three of these seminal papers, which appeared in the prestigious Philosophical Magazine, are included here, along with the published text of Thomsons talk of April 30, 1897, in which he first put the subatomic proposal forward and George Fitzgeralds commentary on this talk.