Ueber die Gegenwart des Kupfers in Cerealien

Ohne Zusammenfassung     

Soybean biodiesel methyl esters,free glycerin and acid number quantification by 1H nuclear magnetic resonance spectroscopy

Production of alternative fuels, such as biodiesel, from transesterification of vegetable oil driven by heterogeneous catalysts is a promising alternative to fossil diesel. However, achieving a successful substitution for a new renewable fuel depends on several quality parameters. ¹H NMR spectroscopy was used to determine the amount of methyl esters, free glycerin and acid number in the transesterification of soybean oil with methanol in the presence of hydrotalcite‐type catalyst to produce biodiesel. Reaction parameters, such as temperature and time, were used to evaluate soybean oil methyl esters rate conversion. Temperatures of 100 to 180 °C and times of 20 to 240 min were tested on a 1 : 12 molar ratio soybean oil/methanol reaction. At 180 °C/240 min conditions, a rate of 94.5 wt% of methyl esters was obtained, where free glycerin and free fatty acids were not detected. Copyright © 2012 John Wiley & Sons, Ltd.     

The rotational spectrum and structure of the phosphine-hydrogen cyanide complex

The rotational spectrum of the weakly bound complex (PH₃, HCN) in its vibrational ground state has been observed by the technique of pulsed-nozzle, Fourier-transform microwave spectroscopy. The isotopic species (PH₃, HC¹⁴N), (PH₃, DC¹⁴N) and (PH₃, HC¹⁵N) exhibit spectra of the symmetric-top type from which accurate values of the spectroscopic constants B₀, D_J, D_JK and X_aa(¹⁴N) have been determined. For (PH₃, HC¹⁴N) the appropriate values are: B₀ = 1553.3709(1) MHz, D_J = 3.306(3) kHz, D_JK = 256.9(6) kHz and X_aa(¹⁴N) = ?4.3591(14) MHz. The geometry of the complex established from the spectroscopic constants is one of C_3v symmetry at equilibrium, with the HCN molecule lying along the C₃ axis of PH₃ and oriented so that it forms a hydrogen bond to the P atom. The effective distance from P to the C nucleus is r(P ? C) = 3.913 Å.     

First-order stark effect and electric dipole moment of H3P … HC15N by pulsed-nozzle fourier-transform microwave spectroscopy

The first-order Stark effect in the J = 4 ← 3, K = 1 transition of the weakly bound dimer H₃P … HC¹⁵ N has been obeserved and measured by pulsed-nozzle Fourier-transform microwave spectroscopy under the selection rules ΔM = O and ΔM = ± 1. The electric dipole moment μ= 4.046(47) D determined for H₃P … HC¹⁵ N has been interpreted in terms of an enhancement Δμ = 0.60 D on dimer formation.     

Kinetics of oxidation of vanadyl acetylacetonate by oxygen in methanolic solution

The kinetics of oxidation of vanadyl acetylacetonate to VO(OH)(OMe)(acac) by molecular O2 in MeOH have been studied spectrophotometrically. The reaction, which is pseudo first-order with respect to [VO(acac)2] and [O2], is inhibited by Hacac and a vanadium(V) complex. The rate data were used to calculate the thermodynamic activation parameters. A mechanism for the reaction is discussed.     

Complexes of functionalized dipyrido[3,2-a:2',3'-c]-phenazine: a synthetic, spectroscopic, structural, and density functional theory study

The ligands 11-bromodipyrido[3,2-a:2',3'-c]phenazine and ethyl dipyrido[3,2-a:2',3'-c]phenazine-11-carboxylate have been prepared and coordinated to ruthenium(II), rhenium(I), and copper(I) metal centers. The electronic effects of substitution of dipyrido[2,3-a:3',2'-c]phenazine (dppz) have been investigated by spectroscopy and electrochemistry, and some photophysical properties have been studied. The crystal structures of [Re(L)(CO)(3)Cl] (L = ethyl dipyrido[3,2-a:2',3'-c]phenazine-11-carboxylate or 11-bromodipyrido[3,2-a:2',3'-c]phenazine) are presented. Density functional theory calculations on the complexes show only small deviations in bond lengths and angles (most bonds within 0.02 Angstroms, most angles within 2 degrees) from the crystallographic data. Furthermore, the vibrational spectra of the strongest Raman and IR bands are predicted to within an average 6 cm(-1) for the complexes [Re(L)(CO)(3)Cl] and [Cu(L)(triphenylphosphine)(2)]BF(4) (in the 1000-1700 cm(-1) region). Spectroscopic and electrochemical evidence suggest that reduction of the complex causes structural changes across the entire dppz ligand. This is unusual as dppz-based ligands typically have electrochemical properties that suggest charge localization with reduction on the phenazine portion of the ligand. The excited-state lifetimes of the complexes have been measured, and they range from ca. 200 ns for the [Ru(L)(2,2'-bipyridine)(2)](PF(6))(2) complexes to over 2 mus for [Cu(11-bromodipyrido[3,2-a:2',3'-c]phenazine)(PPh(3))(2)](BF(4)) at room temperature. The emission spectra suggest that the unusually long-lived excited states of the copper complexes result from metal-to-ligand charge transfer (MLCT) transitions as they are completely quenched in methanol. Electroluminescent films may be fabricated from these compounds; they show MLCT state emission even at low doping levels [<0.1% by weight in poly(vinylcarbazole) polymer matrix].     

A new approach to the synthesis of carbon chains capped by metal clusters

Reactions of Co₃(μ₃-CBr)(μ-dppm)(CO)₇ with {Au[P(tol)₃]}₂{μ-(CC)_n} (n=2–4) have given {Co₃(μ-dppm)(CO)₇}{μ₃:μ₃-C(CC)_nC} [n=2 (1), 3 (2), 4 (3)] containing carbon chains capped by the cobalt clusters. Tetracyanoethene reacts with 2 to give {Co₃(μ-dppm)(CO)₇}₂{μ₃:μ₃-C(CC)₂C[=C(CN)₂]C[=C(CN)₂]C} (4). X-ray structural characterisation of 1, 3 and 4 are reported, that for 3 being the first of a cluster-capped C₁₀ chain.     

Clemmensen Reductions Using Ultrasonic Irradiation

A variety of ketones have been reduced to the corresponding methylene compounds using amalgamated zinc and conducting the reaction in an ultrasonic laboratory cleaner.     

Beyond mathematical content knowledge: A mathematician's knowledge needed for teaching an inquiry-oriented differential equations course

In this research report we examine knowledge other than content knowledge needed by a mathematician in his first use of an inquiry-oriented curriculum for teaching an undergraduate course in differential equations. Collaboratively, the mathematician and two mathematics education researchers identified the challenges faced by the mathematician as he began to adopt reform-minded teaching practices. Our analysis reveals that responding to those challenges entailed formulating and addressing particular instructional goals, previously unfamiliar to the instructor. From a cognitive analytical perspective, we argue that the instructor's knowledge — or lack of knowledge — influenced his ability to set and accomplish his instructional goals as he planned for, reflected on, and enacted instruction. By studying the teaching practices of a professional mathematician, we identify forms of knowledge apart from mathematical content knowledge that are essential to reform-oriented teaching, and we highlight how knowledge acquired through more traditional instructional practices may fail to support research-based forms of student-centered teaching.