LC‐MS identification of derivatized free fatty acids from adipocere in soil samples

Free fatty acids were derivatized as amides (DFFA) by reaction with (R)‐(+)‐1‐phenylethylamine, using a simple, fast and robust reaction scheme. A HPLC method with diode array and ESI MS detection was developed for the analysis of the derivatized substances. Six fatty acids were used in the method development: myristic, linoleic, palmitic, oleic, margaric and stearic acids. Under these conditions the elution of the DFFA are well resolved with retention times raging from 6.9 to 16.0 min. Fatty acids were extracted from cemetery soil and from adipocere formation experimental soils using a Soxhlet extraction, using as solvent ether/dichloromethane (1:1). Each DFFA is characterized by three m/z peaks: molecular weight of the substance; molecular weight of a dimer of the substance; the molecular weight of the dimer plus the atomic mass of sodium. The analysis of soil samples detected the six fatty acids used in the method developed plus palmitoleic and pentadecanoic. Beside this set of eight fatty acids other 13 fatty acids were detected in trace quantities or only in some soils and some were tentatively assigned as: 10‐hydroxystearic, myristoleic, heptadecenoic and arachidic acids.     

Solution Equilibria of Ternary Systems Involving Nickel(II) Ion,Picolinic Acid,and the Amino Acids Histidine,Cysteine, Aspartic and Glutamic Acids

Solution equilibria of the ternary systems Ni(II)–picolinic acid (Hpic) and the amino acids aspartic acid (H₂asp), glutamic acid (H₂glu), cysteine (H₂cys) and histidine (Hhis), where the amino acids are denoted as H _i L, have been studied pH-metrically. The formation constants of the resulting mixed ligand complexes have been determined at 25 °C using a ionic strength 1.0 mol·dm^?3 NaCl. In the Ni(II)–Hpic–H₂asp and Ni(II)–Hpic–H₂glu systems, the complexes [Ni(pic)H₂L]⁺, Ni(pic)HL, [Ni(pic)L]^? and [Ni(pic)L(OH)]^2? were detected. In the Ni(II)–Hpic–H₂cys system the complexes [Ni(pic)H₂L]⁺ and [Ni(pic)L]^? are present. Additionally, in the Ni(II)–Hpic–Hhis system the species [Ni(Hpic)HL]²⁺, Ni(pic)L and [Ni(pic)L(OH)]^? were identified. The species distribution diagrams as functions of pH are briefly discussed.     

Hexanuclear Co4Dy2, Zn4Dy2, and Co4Y2 Complexes with Defect Tetracubane Cores: Syntheses,Structures, and Magnetic Properties

A hexanuclear heterometallic cluster of composition [Dy₂Co₄(L)₄(NO₃)₂(OH)₄(C₂H₅OH)₂] ⋅ 2 C₂H₅OH ( 1 ) was synthesized by employing a Schiff base 2-(((2-hydroxy-3-methoxybenzyl) imino)methyl)-4-methoxyphenol (H₂L) as ligand and utilizing Dy(NO₃)₃ ⋅ 6H₂O and Co(NO₃)₂ ⋅ 6H₂O as metal ion sources. X-ray single-crystal diffraction analysis indicated that complex 1 contains a defect tetracubane core and possesses central symmetric structure, with two Dy^III ions being in the central body position of the molecule and four Co^II ions being arranged at the outer sites. Magnetic studies reveal that complex 1 behaves as single-molecule magnet (SMM) with energy barrier of 27.50 K. To investigate the individual contribution of Dy^III and Co^II ions to the SMM behavior, another two complexes of formulae [Dy₂Zn₄(L)₄(NO₃)₂(OH)₄] ⋅ 4CH₃OH ( 2 ) and [Y₂Co₄(L)₄(NO₃)₂(OH)₄(C₂H₅OH)₂] ⋅ 2 C₂H₅OH ( 3 ) were prepared. Complexes 1 and 3 are isomorphous. The coordination geometries of Dy^III ions in 1 and 2 are different. The Dy^III ions are eight-coordinated in 2 and nine-coordinated in 1 . Complex 2 exhibits SMM behavior with energy barrier of 69.67 K, but complex 3 does not display SMM property. These results reveal that the SMM behaviors of 1 and 2 are mainly originated from Dy^III ions. It might be the higher symmetry of Dy^III ions in 2 that results in the higher energy barrier.     

On the graded central polynomials for elementary gradings in matrix algebras

Let \(F\) be a field of characteristic zero. Let \(M_{n}(F)\) be the algebra of all \(n \times n\) matrices over \(F\). We have found, in this article, a generating set for the graded central polynomials of \(M_{n}(F)\) when it is equipped with an elementary grading whose neutral component coincides with the diagonal.     

Integral transforms for three-dimensional steady turbulent dispersion in rivers and channels

A three-dimensional steady-state mathematical model is considered for predicting the fate of dissolved contaminants in rivers and channels under turbulent flow conditions. The model allows for variable velocity fields and non-uniform turbulent diffusivities within channels of rectangular cross sections. Making use of the Generalized Integral Transform Technique (GITT), a hybrid numerical–analytical solution for the concentration fields is then obtained. The solution convergence behavior is investigated and the criterion for reordering the terms in the infinite series is discussed, with the aim of reducing the computational effort associated with the multiple eigenfunction expansions. A test case is presented to illustrate the proposed approach.     

Nanoparticle formation and ultrathin film electrodeposition of carbazole dendronized polynorbornenes prepared by ring-opening metathesis polymerization

We report on the synthesis, electropolymerization, and nanoparticle formation of a series of electroactive carbazole-terminated dendronized linear polynorbornenes prepared by living ring-opening metathesis polymerization (ROMP). The molecular weight (MW) of the dendronized polymers was controlled by varying the feed ratio between the dendronized monomer and first-generation Grubbs' catalyst. Ultrathin films were prepared by electrodeposition. The electrochemical behavior and viscoelastic properties of such films were found to be highly dependent on the dendron generation and linear polymer MW as studied by electrochemical quartz crystal microbalance (E-QCM). Moreover, nanoparticle formation and size/shape control were observed by tuning the surface wetting properties of the substrate during adsorption and by intramolecular cross-linking via chemical oxidation in solution.     

Activity coefficients of NaCl in PEG 4000 + water mixtures at 288.15, 298.15 and 308.15 K

The electromotive force of the cell containing two ion-selective electrodes (ISE),

Na-ISE|NaCl (m), PEG ??4000 (Y), H₂O (100−Y)|Cl-ISE$\text{Na-ISE}|\text{NaCl}(m),\text{PEG}\text{\hspace{0.17em}??}4000(Y),{\text{H}}_2\text{O}(100-Y)|\text{Cl-ISE}$

A numerical algorithm for zero counting. II: Distance to ill-posedness and smoothed analysis

We show a Condition Number Theorem for the condition number of zero counting for real polynomial systems. That is, we show that this condition number equals the inverse of the normalized distance to the set of ill-posed systems (i.e., those having multiple real zeros). As a consequence, a smoothed analysis of this condition number follows.     

Markov chain modeling of polymer translocation through pores

We solve the Chapman-Kolmogorov equation and study the exact splitting probabilities of the general stochastic process which describes polymer translocation through membrane pores within the broad class of Markov chains. Transition probabilities, which satisfy a specific balance constraint, provide a refinement of the Chuang-Kantor-Kardar relaxation picture of translocation, allowing us to investigate finite size effects in the evaluation of dynamical scaling exponents. We find that (i) previous Langevin simulation results can be recovered only if corrections to the polymer mobility exponent are taken into account and (ii) the dynamical scaling exponents have a slow approach to their predicted asymptotic values as the polymer's length increases. We also address, along with strong support from additional numerical simulations, a critical discussion which points in a clear way the viability of the Markov chain approach put forward in this work.