The evolutionary ecology of technological innovations

Technological evolution has been compared to biological evolution by many authors over the last two centuries. As a parallel experiment of innovation involving economic, historical, and social components, artifacts define a universe of evolving properties that displays episodes of diversification and extinction. Here, we critically review previous work comparing the two types of evolution. Like biological evolution, technological evolution is driven by descent with variation and selection, and includes tinkering, convergence, and contingency. At the same time, there are essential differences that make the two types of evolution quite distinct. Major distinctions are illustrated by current specific examples, including the evolution of cornets and the historical dynamics of information technologies. Due to their fast and rich development, the later provide a unique opportunity to study technological evolution at all scales with unprecedented resolution. Despite the presence of patterns suggesting convergent trends between man‐made systems end biological ones, they provide examples of planned design that have no equivalent with natural evolution.     

The further unified theory for modifications of <Emphasis Type="Italic">λ</Emphasis>-closed sets and gΛ-sets using minimal structures

We introduce and study two new notions of sets called (Λ, mn)-closed sets and gΛ _mn -sets, which are defined on a nonempty set with two minimal structures. These sets enables us to unify modifications of λ-closed sets [1] and generalized Λ-sets [15], respectively. Moreover, we give a new characterization of the class of mn-T _1/2 [17] by using gΛ _mn -sets.     

Transition metal complexes based on thiophene-dithiolene ligands

The chemistry of transition metal dithiolene complexes based on thiophene-dithiolene ligands (TD) is reviewed, from the ligand synthesis and complex preparation to the molecular structure and solid state physical properties of different compounds based on them. The ligands considered are based mainly either on simple thiophene-dithiolates (α-tpdt = 2,3-thiophenedithiolate, dtpdt = 4,5-dihydro-2,3-thiophenedithiolate, and tpdt = 3,4-thiophenedithiolate), or in more extended and delocalised dithiolate ligands (α-tdt = 3-({5-[(2-cyanoethyl)thio]-2-thieno[2,3-d][1,3]dithiol-2-ylidene-1,3-dithiol-4-yl}thio)propanenitrile and dtdt = 3-{5-[(2-cyanoethyl)thio]-2-(5,6-dihydrothieno[2,3-d][1,3]dithiol-2-ylidene-1,3-dithiol-4-yl)thio}propanenitrile) that besides the thiophenic ring also incorporates a fused TTF moiety. Dithiolene complexes based on ligands containing appended thiophenic units will also be briefly considered. The structural variability of these complexes that in addition to the usual square planar coordination geometry, M(TD)₂, can also present dimeric, [M(TD)₂]₂, or cluster structures such as [Cu₄(TD)₃] and [Ni₄(TD)₆], is addressed. The role of the thiophene group and its ability to enhance electronic delocalisation from the metal dithiolene core throughout the ligand and to establish solid state networks of S?S interactions is discussed. The importance of these complexes as useful building blocks to prepare molecular materials with very interesting magnetic and transport properties, ranging from metamagnets to Single Component Molecular Metals, is illustrated by different compounds based on them.     

Comparative theoretical study of small Rhn nanoparticles (2 ≤ n ≤ 8) using DFT methods

This work is aimed at identifying some key characteristics (energy, geometry, and spin) concerning Rh_n particles (2 = n ≤ 8) to perform further studies on adsorption and coadsorption sites of pollutants (CO and NO). The DFT methods of the Gaussian 03 program with the LANL2DZ basis set and the LANL2 potential are used. With the purpose to obtain a better nanoparticles definition, five different functionals were tested: B3LYP, O3LYP, BPW91, BP86, and HCTH; and the corresponding results are used to determine which of them best describes distances, spin, and gives acceptable highest vibration frequency and binding energy values, by comparing these results with values measured or calculated by many other authors. For the structure optimization process of the particles, the initial geometric shape was taken mainly from the literature, using the Rh–Rh distance: 2.67 Å, known for the bulk; and doing a complete optimization. We also considered flat nanoparticles structures, which most of them display three‐dimensional structures after the optimization process. The few flat shapes are mainly higher in energy than those of three‐dimensional structure. For some Rh_n particles for different n values, the spin of the ground state present degeneration. In some cases, the optimization process changes the initial geometry, but in most cases, there are only minor changes in bonds and geometry. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

New stibines containing acetal and formyl group: Platinum complex and unexpected oxastibol derivative

A new tertiary stibine ligand (1) containing acetal group at the ortho-position has been synthesized. This new stibine was then complexed with to obtain trans-PtCl₂L₂ (2) where stibine acts as a monodentate ligand. The acetal was hydrolyzed in a slightly acidic medium and forms a very new stibine (3) containing formyl group at the ortho-position. When (3) was reduced with NaBH₄ an unusual oxastibol (4) derivative was obtained under the experimental conditions used.All the compounds were characterized by IR, mass, ¹H, ¹³C, COSY and HETCOR NMR spectroscopy. The molecular structures of (2), (3) and (4) were determined. Compound (3) crystallizes in two different polymorphs (3a) and (3b) and both the polymorphs show hypervalent antimony with three Sb?O interactions and the molecule exists in O-cis-exo configuration. Compound (4) shows intramolecular Sb?O interactions. To the best of our knowledge this is the first report on organoantimony compounds containing carbonyl groups though their phosphorus and bismuth analogues are well known. Compound (2) shows helicoidal chirality, which is a very new concept in antimony chemistry     

Extraction of basic drugs from whole blood and determination by high performance liquid chromatography

Chromatographia - A new method for the extraction of basic drugs from whole blood based on the use of a buffered protein precipitating reagent at pH9, to form NiWO4 in biological fluids and a...     

A search for single-electron transfer (set) mechanisms in the reaction of 1,3-dithianyl- and 1,3-oxathianyllithiums with primary halides

The reaction of 1, 3-dithianyl-, 2-methyl-1, 3-dithianyl- and oxathianyllithium with 6-halo-1-hexenes affords the products expected from a S_N2 (rather than SET) mechanism.     

Comparison of different high-performance liquid chromatographic systems for the purification of adrenal and gonadal steroids prior to immunoassay

The high-performance liquid chromatography of nineteen hormonal steroids with special respect to its suitability for routine purification of these steroids from crude, organic extracts of biological fluids prior to final quantitation by immunoassay has been studied. In all systems the gradient elution technique was applied. Separation of steroids has been investigated using different stationary phases chemically coated with non-polar, hydroxyl, NO2 and CN groups. Reproducibility of retention times was studied on a stationary phase coated with hydroxyl groups (DIOL column) using different organic eluents. Coefficients of variation range from 0.76 to 8.16%. Reproducibility was shown to be unequivocally better in the gradient part than in the isocratic part of the chromatographic run. In contrast to the other steroids, 18-hydroxylated steroids were more or less unstable in certain systems studied. As to resolution and reproducibility, the DIOL column run with an n-hexane-dioxane gradient has been shown to be superior to the other systems studied.     

The electrochemistry of square planar macrocyclic nickel complexes and the reaction of Ni(I) with alkyl bromides: Tetradentate Schiff base complexes

The electrochemistry of nine square planar macrocyclic Schiff base complexes of Ni(II) has been investigated in aprotic solvents. It is shown that all form Ni(I) complexes, and with one exception these species may be reacted with alkyl bromides in processes which are catalytic with respect to the nickel complex. The dependence of the electrochemical parameters and the mechanism and kinetics of the coupled chemical reactions on the structure of the ligands is discussed.     

TG and DSC investigation of gallstone samples collected from patients submitted to cholecystectomy

In the present work are performed the TG and DSC study of gallstone samples collected from patients submitted to cholecystectomy at the Hospital Universitário Onofre Lopes of Universidade Federal do Rio Grande do Norte, in Natal, Rio Grande do Norte State, Brazil. The gallstone samples were characterized by elemental analysis and infrared spectroscopy. Standard cholesterol was used for all analysis as comparison with the gallstones. Is verified that cholesterol is the main chemical component of all studied gallstone samples. The thermoanalytical study was performed on air and nitrogen atmospheres. The presence of cholesterol as the main chemical component of all gallstone samples is confirmed by TG and DSC results.