Michael additions of primary and secondary amines to acrylonitrile catalyzed by lipases

The present Letter details our findings on the lipase-catalyzed Michael reactions between primary or secondary amines and acrylonitrile. Several lipases were evaluated, and good results were obtained leading to the formation of Michael adducts in shorter reaction times than the uncatalyzed reactions.     

Changes of iron concentrations in skin and plasma of patients with hemochromatosis along therapy

Skin as a manageable organ can provide direct or indirect information of tissue iron overload resulting from inherited disorders as hemochromatosis. Patients with hemochromatosis were evaluated at three consecutive phases along the therapy programme. Nuclear microprobe techniques were used to assess skin iron and Total Reflection X-ray Fluorescence to determine the plasma iron concentrations. Results showed that iron pools were differently correlated at the three therapy phases. These variations highlighted the value of skin iron content to assess organ iron deposition and therapy efficacy. Skin iron content can be used for a better management of patients with iron overload pathologies.     

Optical fiber biosensor coupled to chromatographic separation for screening of dopamine, norepinephrine and epinephrine in human urine and plasma

An optical fiber biosensor has been developed for the determination of catecholamines (dopamine, norepinephrine and epinephrine) based on the recognition capacity of the enzyme laccase. In this study, a glass tube constituted by a fused silica fiber coated with a film of polystyrene/divinylbenzene resin (PS/DVB) was used for catecholamines separation. Firstly, the analyzer was tested for calibration and its analytical performance for catecholamines detection was compared with a classical analytical method, namely high performance liquid chromatography-electrochemical detector (HPLC-ED). The developed analytical device shows a high potential for catecholamines quantification with a detection limit of 2.1, 2.6 and 3.4 pg mL⁻¹ for dopamine, norepinephrine and epinephrine, respectively. The analytical sensitivity, inferred from the slope of the calibration curves established for a range of concentrations between 5 and 125 pg mL⁻¹, was found to be 0.344, 0.252 and 0.140 dB/pg mL⁻¹ for dopamine, norepinephrine and epinephrine, respectively. Furthermore, catecholamines speciation with the PS/DVB fiber was completely achieved in 3 min. The analytical performance of the reported sensor was also evaluated and found adequate for catecholamines determination in human urine and plasma samples.     

Measuring inter-pulse intervals in sperm whale clicks: consistency of automatic estimation methods

Sperm whale clicks are characterized by a multi-pulsed structure. The time lag between consecutive pulses, i.e., the inter-pulse interval (IPI), is related to the size of the sound production organ such that its measurement provides a means to acoustically estimate the size of individual whales. Due to off-axis effects the identification of pulses is, however, not always straightforward, and automatic measurement methods provide not only more objective estimation, but may also facilitate IPI estimation in cases where single click measurements are ambiguous. In particular, averaging measurements over a time series of clicks from the same whale could enhance the discrimination of time invariant pulses. The authors developed two automatic methods of automatic IPI measurement based on waveform and autocorrelation averaging and compared their accuracy and consistency with other previously used methods. Manual measurement by an experienced operator provided the most self-consistent estimates. The autocorrelation averaging technique had the best overall performance of the automated methods achieving a very similar performance to manual measurement. On some recordings cepstrum averaging methods converged when autocorrelation did not. Therefore, applying both of these automated methods and choosing the best of the two are recommended.     

Application of copper(i) iodide/diorganoyl dichalcogenides to the synthesis of 4-organochalcogen isoquinolines by regioselective cn and cchalcogen bond formation

A copper-catalyzed cyclization of (ortho-alkynyl)benzaldimines with diorganoyl dichalcogenides allowed the synthesis of 4-organochalcogen isoquinolines, whereas the presence of base in the reaction medium inhibited the product formation producing the undesirable isoquinoline without the organochalcogen atom at the 4-position. The cyclization reaction was carried out by using CuI (20?%) as a catalyst with diorganoyl dichalcogenides (1.5?equiv) in the presence of DMF at 100?°C. Furthermore, the reaction did not require an argon atmosphere and was carried out in an open flask. The cyclization reaction tolerated a variety of functional groups both in ortho-alkynylbenzaldimines and diorganoyl dichalcogenides, such as trifluoromethyl, chloro, fluorine, and methoxyl, to give the six-membered heterocyclic ring exclusively through a 6-endo-dig cyclization process. The organochalcogen group present at the 4-position of the isoquinoline ring was further subjected to a selective chalcogen-lithium exchange reaction followed by the addition of aldehydes to afford the desired secondary alcohols in good yields. The obtained isoquinolines also proved to be suitable substrates for the Suzuki and Sonogashira coupling conditions affording the corresponding products through C?C bond formation.     

Packing interactions in hydrated and anhydrous forms of the antibiotic Ciprofloxacin: a solid-state NMR, X-ray diffraction, and computer simulation study

We present an experimental NMR, X-ray diffraction (XRD), and computational study of the supramolecular assemblies of two crystalline forms of Ciprofloxacin: one anhydrate and one hydrate forming water wormholes. The resonance assignment of up to 51 and 54 distinct (13)C and (1)H resonances for the hydrate is reported. The effect of crystal packing, identified by XRD, on the (1)H and (13)C chemical shifts including weak interionic H-bonds, is quantified; (1)H chemical shift changes up to ～-3.5 ppm for CH···π contacts and ～+2 ppm (CH···O((-))); ～+4.7 ppm (((+))NH···O((-))) for H-bonds. Water intake induces chemical shift changes up to 2 and 5 ppm for (1)H and (13)C nuclei, respectively. Such chemical shifts are found to be sensitive detectors of hydration/dehydration in highly insoluble hydrates.     

Synthesis and antidepressant-like activity of selenophenes obtained via iron(III)-PhSeSePh-mediated cyclization of Z-selenoenynes

We present here the synthesis and antidepressant-like action of a series of 2,5-disubstituted-3-(organoseleno)-selenophenes prepared by a novel synthetic route, the FeCl(3)-diorganyl dichalcogenide-mediated intramolecular cyclization of (Z)-chalcogenoenynes. The cyclized products were obtained in good yields. The results showed that 2c, 2d, 2e and 2o, evaluated in the mouse forced-swimming test, elicited an antidepressant-like activity. The studies clearly show that the phenyl group at the 2-position and an organoselenium group at the 3-position of the selenophene ring are essential for the antidepressant-like activity of selenophenes. A close inspection of the results also revealed that the fluorophenyl portion in the organoselenium group is fundamental for the antidepressant-like action of this class of organochalcogens.     

The block sphericity test—exact and near‐exact distributions for the likelihood ratio statistic

Using a suitable decomposition of the null hypothesis of the sphericity test for several blocks of variables, into a sequence of conditionally independent null hypotheses, we show that it is possible to obtain the expressions for the likelihood ratio test statistic, for its hth null moment, and for the characteristic function of its logarithm. The exact distribution of the logarithm of the likelihood ratio test statistic is obtained in the form of a sum of a generalized integer gamma distribution with the sum of a given number of independent logbeta distributions, taking the form of a single generalized integer gamma distribution when each set of variables has two variables. The development of near‐exact distributions arises, from the previous decomposition of the null hypothesis and from the consequent‐induced factorization of the characteristic function, as a natural and practical way to approximate the exact distribution of the test statistic. A measure based on the exact and approximating characteristic functions, which gives an upper bound on the distance between the corresponding distribution functions, is used to assess the quality of the near‐exact distributions proposed and to compare them with an asymptotic approximation on the basis of Box's method. Copyright © 2011 John Wiley & Sons, Ltd.     

A branch-and-price approach for harvest scheduling subject to maximum area restrictions

Recently, research on exact methods has been undertaken to solve forest management problems subject to constraints on the maximum clearcut area by using the area restriction model approach. Three main basic integer programming models for these problems have been discussed in the literature: the so-called cluster, path and bucket formulations. Solving these models via branch-and-bound, where all variables and constraints are used a priori, is adequately suited for real problems of a small to medium size, but is not appropriate for larger problems. In this paper, we describe a branch-and-price approach for the cluster model, and we show that this formulation dominates the bucket model, by completing the results of the dominance relationships between the bounds of the three models. Branch-and-price was tested on real and hypothetical forests ranging from 45 to 2945 stands and temporal horizons ranging from three to twelve periods were employed. Results show that the solutions obtained by the proposed approach stood within 1% of the optimal solution and were achieved in a short computation time. It was found that branch-and-bound was unable to produce solutions for most forests from 850 stands with either eleven or an average number of stands per clearcut greater or equal than eight.     

The chemical ecology of cyanobacteria

This review covers the literature on the chemically mediated ecology of cyanobacteria, including ultraviolet radiation protection, feeding-deterrence, allelopathy, resource competition, and signalling. To highlight the chemical and biological diversity of this group of organisms, evolutionary and chemotaxonomical studies are presented. Several technologically relevant aspects of cyanobacterial chemical ecology are also discussed.