Syntheses, crystal structure and spectroscopic characterization of new platinum(II) dithiocarbimato complexes

The reaction of 4-iodobenzenesulfonamide or 4-fluorobenzenesulfonamide with CS₂ and KOH in dimethylformamide yielded the potassium N-R-sulfonyldithiocarbimates, K₂(RSO₂NCS₂) [R = 4-IC₆H₄ (1) and 4-FC₆H₄ (2)]. These salts reacted with K₂[PtCl₄] in water/methanol to yield complex anions bis(N-R-sulfonyldithiocarbimato)platinate(II), which were isolated as their tetrabutylammonium salts, (Bu₄N)₂[Pt(RSO₂NCS₂)₂] [R = 4-IC₆H₄ (3) and 4-FC₆H₄ (4)]. The structures of 2–4 were determined by X-ray crystallography. The Pt²⁺ in both complexes 3 and 4 lies at the inversion centre and the PtS₄ moiety has a distorted square-planar configuration. The compounds were also characterized by IR, ¹H NMR and ¹³C NMR spectroscopies, and elemental analyses. The molar conductance data are consistent with the fact that 3 and 4 are dianionic complexes.     

Effect of Temperature on Thermophysical Properties of Ethanol + Aliphatic Alcohols (C<Subscript>4</Subscript>–C<Subscript>5</Subscript>) Mixtures

Summary. Speeds of sound, densities, and refractive indices of the binary mixtures containing ethanol+(2-methyl-1-propanol, 2-methyl-1-butanol, 1-pentanol, or 3-methyl-1-butanol) were measured at 288.15 ≤ T/K ≤ 323.15 and atmospheric condition in the whole compositional range. The effect of temperature was analyzed by several chemical terms.     

Study of the nitric oxide system in the rat cerebellum during aging

Background  

The cerebellum is the neural structure with the highest levels of nitric oxide, a neurotransmitter that has been proposed to play a key role in the brain aging, although knowledge concerning its contribution to cerebellar senescence is still unclear, due mainly to absence of integrative studies that jointly evaluate the main factors involved in its cell production and function. Consequently, in the present study, we investigate the expression, location, and activity of nitric oxide synthase isoenzymes; the protein nitration; and the production of nitric oxide in the cerebellum of adult and old rats.     

A synthetic, chloride-selective channel that alters chloride transport in epithelial cells

An Ussing chamber was used to demonstrate that synthetic amphiphilic anion transporters function as chloride transporters in mammalian airway epithelial cells.     

Nonwandering set of points of skew-product maps with base having closed set of periodic points

The aim of the present paper is to study the structure of the nonwandering set of points Ω() for the skew-product maps of the unit square , (x,y)→(f(x),g(x,y)), with base f having closed set of periodic points. For every and every point (x,y) with x periodic of period p_x by f and y not chain recurrent of F^p_x|_Ix, where , we prove that (x,y)Ω(F). On the other hand we construct a map with an isolated fixed point x₀ of f and y₀Ω(F|_Ix0) such that (x₀,y₀)Ω(F₀).     

How fast do stock prices adjust to market efficiency? Evidence from a detrended fluctuation analysis

In this paper we analyse price fluctuations with the aim of measuring how long the market takes to adjust prices to weak-form efficiency, i.e., how long it takes for prices to adjust to a fractional Brownian motion with a Hurst exponent of 0.5. The Hurst exponent is estimated for different time horizons using detrended fluctuation analysis–a method suitable for non-stationary series with trends–in order to identify at which time scale the Hurst exponent is consistent with the efficient market hypothesis. Using high-frequency share price, exchange rate and stock data, we show how price dynamics exhibited important deviations from efficiency for time periods of up to 15 min; thereafter, price dynamics was consistent with a geometric Brownian motion. The intraday behaviour of the series also indicated that price dynamics at trade opening and close was hardly consistent with efficiency, which would enable investors to exploit price deviations from fundamental values. This result is consistent with intraday volume, volatility and transaction time duration patterns.     

Suiformes orthologous satellite DNAs as a hallmark of Pecari tajacu and Tayassu pecari (Tayassuidae) evolutionary rearrangements

In a broad general way, eukaryotic satellite DNA sequences are characterized by a highly dynamic molecular behavior due to concerted evolution that leads to rapid change between repeat sequences of different species, achieved by amplification of new variants during speciation or by gradual sequence evolution due to the accumulation of nucleotide substitutions. There are, although exceptions for this almost universal rule. We isolated variants from both the Mc1 and Ac2 pig (Sus scrofa, Suidae) satellite DNA families from the genomes of two Tayassuidae members: Pecari tajacu and Tayassu pecari, which have highly derived karyotypes. The presence of these sequences in both families’ genomes (Suidae and Tayassuidae) implies their existence in a common ancestor, what confers to the variants the status of orthology and the approximate age of, at least 40 million years.While at the molecular composition level these orthologous sequences are highly homologous, cross-species physical mapping revealed a completely different chromosomal location in Suidae versus Tayassuidae families, most probably, reflecting the high level of divergence and chromosomes evolution pathways after radiation of each family. Detailed comparative analysis of the satellites assignment on the peccary's chromosomes revealed its co-localization with homologous evolutionary breakpoints in both species, suggesting their involvement in the rearrangement events. The complex behavior of the repeats evolution in the pig/peccaries genomes is here clearly illustrated. These sequences are molecularly preserved for a considerable period of time and display slow rates of sequence change, but show a dynamic motion behavior throughout the peccary's genomes that accompanied the great architectonic reorganization of Tayassuidae chromosomes during evolution.     

Temperature-Controlled Stereodivergent Synthesis of 2,2′-Biflavanones Promoted by Samarium Diiodide

In this work, the first example of a radical stereodivergent reaction directed towards the stereoselective synthesis of both (R*,R*)- and (R*,S*)-2,2′-biflavanones promoted by samarium diiodide is reported. Control experiments showed that the selectivity of this reaction was exclusively controlled by the temperature. It was possible to generate a variety of 2,2′-biflavanones bearing different substitution patterns at the aromatic ring in good-to-quantitative yields, being both stereoisomers of the desired compounds obtained with total or high control of selectivity. A mechanism that explains both the generation of the corresponding 2,2′-biflavanones and the selectivity is also discussed. The structure and stereochemistry determination of each isomer was unequivocally elucidated by single-crystal X-ray diffraction experiments.     

Reversible Lysine Modification on Proteins by Using Functionalized Boronic Acids

Iminoboronates have been utilized to successfully install azide and alkyne bioorthogonal functions on proteins, which may then be further reacted with their bioorthogonal counterparts. These constructs were also used to add polyethylene glycol (PEG) to insulin, a modification which has been shown to be reversible in the presence of fructose. Finally, iminoboronates were used to assemble a folic acid/paclitaxel small‐molecule/drug conjugate in situ with an IC₅₀ value of 20.7 nM against NCI‐H460 cancer cells and negligible cytotoxicity against the CRL‐1502 noncancer cells.