Tuning the Fluorescence Through Reorientation of the Axle in Calix[6]arene-Based Pseudorotaxanes

This work describes a calix[6]arene-based wheel that binds, in non-polar media, a stilbazolium salt to yield a mixture of pseudorotaxane orientational isomers. The isomer's abundance ratio evolves with time and can be reversibly tuned by adjusting the temperature. The spectroscopic properties, and notably the emission spectrum, of the bound guest depend on its orientation inside the non-palindromic wheel, suggesting such a system as a switch with spectroscopic readout.     

Determination of four thiophenethylamine designer drugs (2C-T-series) in human plasma by capillary electrophoresis with mass spectrometry detection

In recent years, the frequent appearance of phenethylamine designer drugs on the illicit drug market has been a matter of concern for all authorities involved. New phenethylamine drugs are being introduced because these compounds are not covered by existing legislation. Therefore, the new drugs cannot be considered illicit drugs until their names are officially recognized. This paper describes a method to screen for and quantify four 2,5-methylenedioxy-derivatives of 4-thio-phenethylamine (2C-T-series) in human plasma, using capillary electrophoresis coupled with electrospray ionisation-mass spectrometry (CE-ESI-MS). Prior to CE-MS analysis, a simple liquid extraction was used for sample cleanup. The method was validated according to international guidelines.     

Hydrodynamic cavitation: from theory towards a new experimental approach

Hydrodynamic cavitation is analysed by a global thermodynamics principle following an approach based on the maximum irreversible entropy variation that has already given promising results for open systems and has been successfully applied in specific engineering problems. In this paper we present a new phenomenological method to evaluate the conditions inducing cavitation. We think this method could be useful in the design of turbo-machineries and related technologies: it represents both an original physical approach to cavitation and an economical saving in planning because the theoretical analysis could allow engineers to reduce the experimental tests and the costs of the design process.      

A Comparison on Five Sediment Decomposition Procedures for Determining Anthropogenic Trace Metal Pollution

Abstract

Five different procedures of sediment decomposition were compared, for evaluating the one more appropriated for assessing anthropogenic metal pollution. Exchangeable-metal extraction in sodium acetate, weak extraction in hydroxylamine hydrochloride/acetic acid, moderate extraction in diluted hydrochloric acid, oxidising strong acid digestion and total decomposition with hydrofluoric acid were tested. The mildest sodium acetate attack, which gives also better account for the bioavailable metal fraction, is the more effective in enhancing differences between polluted sediments and nonpolluted ones. Copper, lead and zinc are the best indicators of trace metal pollution of surface sediments.     

Enantioselective gold-catalyzed synthesis of polycyclic indolines

The synthesis of architecturally complex polycyclic fused indolines is achieved in a chemo-, regio-, and stereodefined manner, via an enantioselective gold-catalyzed cascade hydroindolination/iminium trapping synthetic sequence. Highly functionalized tetracyclic fused furoindolines (2) and dihydropyranylindolines (4) are synthesized in moderate to good yields and enantiomeric excesses of up to 87%.     

Balancing of agricultural census data by using discrete optimization

In the case of large-scale surveys, such as a Census, data may contain errors or missing values. An automatic error correction procedure is therefore needed. We focus on the problem of restoring the consistency of agricultural data concerning cultivation areas and number of livestock, and we propose here an approach to this balancing problem based on optimization. Possible alternative models, either linear, quadratic or mixed integer, are presented. The mixed integer linear one has been preferred and used for the treatment of possibly unbalanced data records. Results on real-world Agricultural Census data show the effectiveness of the proposed approach.     

A few level approach for the electronic partition function of atomic systems

A simplified model to calculate partition functions and thermodynamic properties of atomic species is presented. This model consists in grouping the atomic states in few virtual levels. Their statistical weights and energies are calculated summing or mediating over the states belonging to each group. The partition function is calculated considering the virtual levels to follow the Boltzmann distribution. A theoretical foundation of the model has been described for a general case and verified for hydrogen, oxygen and nitrogen atoms. Two- and three-level models are adequate to keep the error within a few percent. A second order correction term can also be added to further reduce the error without changing the advantages of the model.     

A note on Aerts' description of separated entities

The theoretical scheme proposed by Aerts for describing two separated entities as a whole within a question-state structure is considered. The quoted author claims that two relevant axioms characterizing quantum physics cannot hold for a quantum, nonclassical entity consisting of two quantum separate entities. We suggest that Aerts' theory is not adequate, from the empirical point of view, to describe this situation.     

Heavy metals and nutrients in coastal,surface seawaters (Gulf of Trieste,Northern Adriatic Sea): an environmental study by factor analysis

Trace metals and nutrients were monitored voltammetrically and spectrophotometrically during a one-year period (1992/93) in the filtered fraction of coastal surface seawaters sampled with a monthly frequency at 6 different sites in the Gulf of Trieste (Northern Adriatic Sea), to evaluate the degree of pollution in an area receiving industrial, agricultural and urban wastes. The sites devoted to hatcheries of edible mussels are of particular interest. A multivariate statistical analysis of the collected concentration data by the principal component method allows to identify the sources and typology of pollution, and to discriminate between the quality of waters at the different sampling sites. The coastal waters in the Gulf of Trieste seem to be comparable to, or better than, waters of analogous areas in the Mediterranean Sea.     

Structural basis for the broad-spectrum inhibition of metallo-beta-lactamases by thiols

The development of broad-spectrum metallo-beta-lactamase (MBL) inhibitors is challenging due to structural diversity and differences in metal utilisation by these enzymes. Analysis of structural data, followed by non-denturing mass spectrometric analyses, identified thiols proposed to inhibit representative MBLs from all three sub-classes: B1, B2 and B3. Solution analyses led to the identification of broad spectrum inhibitors, including potent inhibitors of the CphA MBL (Aeromonas hydrophila). Structural studies revealed that, as observed for other B1 and B3 MBLs, inhibition of the L1 MBL thiols involves metal chelation. Evidence is reported that this is not the case for inhibition of the CphA enzyme by some thiols; the crystal structure of the CphA-Zn-inhibitor complex reveals a binding mode in which the thiol does not interact with the zinc. The structural data enabled the design and the production of further more potent inhibitors. Overall the results suggest that the development of reasonably broad-spectrum MBL inhibitors should be possible.