A Hexameric Cationic Copper(II) Metallacrown as a Pertechnetate and Perrhenate Scavenger

Materials based on the cationic copper(II) hexanuclear 18‐membered metallacrown [18‐MC ‐6]⁶⁺ (2phH=2‐piconyl hydrazide) and tetrafluoroborate, perchlorate, nitrate, sulfate, and perrhenate anions were prepared by an easy method in aqueous medium. Single‐crystal X‐ray characterization of six members of this new family of complexes showed that the anions are attached to the metallacrown by direct coordination to a copper cation or by hydrogen‐bonding interaction with the center of the hexamer. The stable cationic nature of the complexes and their ability to bind different anions allows them to adsorb and immobilize environmentally relevant anions such as MO₄^? (M=Tc, Re). The MO₄^? trapping capacities suggest that these materials would be useful in the treatment of oxoanionic contaminants in water.     

Detection of sibutramine administration: a gas chromatography/mass spectrometry study of the main urinary metabolites

A gas chromatographic/mass spectrometric (GC/MS) study aimed at identifying the metabolites of sibutramine (1-(4-chlorophenyl)-N,N-dimethyl-alpha-(2-methylpropyl)cyclobutanemethanamine) in urine is described. Urinary excretion of sibutramine metabolites following the oral administration of a single dose of sibutramine was followed by GC/MS analysis. After identification of the chromatographic signals corresponding to the six main urinary metabolites, the fragmentation pattern was studied in electron ionization (EI) mode after derivatization to the corresponding methyl and trimethylsilyl derivatives. Urine samples were pretreated according to a reference procedure (liquid/liquid separation, enzymatic hydrolysis, pre-concentration under a stream of nitrogen and derivatization, either under thermal incubation and by microwave irradiation). All sibutramine metabolites were excreted as glucuroconjugates, and retain the chiral carbon present in the sibutramine skeleton. The metabolites identified included mono-desmethylsibutramine (nor-sibutramine), bi-desmethylsibutramine (nor-nor-sibutramine), and the corresponding hydroxylated compounds, the hydroxylation taking place either on the cyclobutane or on the isopropyl chain. The excretion profiles of the different metabolites were also evaluated. From an analytical point of view, the method can be applied to different fields of forensic analytical toxicology, including anti-doping analysis. Although the lack of certified reference materials does not allow a precise determination of the limits of detection (LODs) of all the sibutramine metabolites, an estimation taking into account the response factor of similar compounds ensures that all metabolites are still clearly detectable in a range of concentrations between 10 and 50 ng/mL, thus satisfying the minimum required performance limits (MRPLs) of the World Anti-Doping Agency (WADA).     

The Structural Determinants for α1-Adrenergic/Serotonin Receptors Activity among Phenylpiperazine-Hydantoin Derivatives

Several studies confirmed the reciprocal interactions between adrenergic and serotoninergic systems and the influence of these phenomena on the pathogenesis of anxiety. Hence, searching for chemical agents with a multifunctional pharmacodynamic profile may bring highly effective therapy for CNS disorders. This study presents a deep structural insight into the hydantoin-arylpiperazine group and their serotonin/α-adrenergic activity. The newly synthesized compounds were tested in the radioligand binding assay and the intrinsic activity was evaluated for the selected derivatives. The computer-aided SAR analysis enabled us to answer questions about the influence of particular structural fragments on selective vs. multifunctional activity. As a result of the performed investigations, there were two leading structures: (a) compound 12 with multifunctional adrenergic-serotonin activity, which is a promising candidate to be an effective anxiolytic agent; (b) compound 14 with high α_1A/α_1D affinity and selectivity towards α_1B, which is recommended due to the elimination of probable cardiotoxic effect. The structural conclusions of this work provide significant support for future lead optimization in order to achieve the desired pharmacodynamic profile in searching for new CNS-modulating agents.     

The radiation shielding offered by the commercial glass installed in Bangladeshi dwellings

One sign of a vibrant Bangladeshi economy has been the move away from the use of more traditional housing materials towards a preference for modern constructional media. Glass, one such example, used both decoratively and in a structural context, offers various advantageous properties and facets including a protective feature against radiation that has not previously been considered. Current interest examines the dosimetric possibilities offered by the commercial glass as a secondary shield and also in retrospective ionising radiation exposure analysis. Four popular brands of window glass are investigated, all available within the local market (PHP-Bangladesh, Usmania-Bangladesh, Nasir-Bangladesh and Rider-China), all with the same thickness and colour, varying in terms of elemental weight fractions as evaluated by energy dispersive X-ray analysis. As potential attenuators of transmitted radiation thereby forming secondary barriers against radiation exposure from penetrating radiations, the four brands of glass have been studied using photon energies from 59 up to 1332 keV, a range of values representative of that potentially encountered in incidents. Use has been made of a well-shielded high-purity germanium γ-ray spectrometer and associated electronics, providing for evaluation of the characteristic barrier parameters of half-value layer, radiation protection efficiency and effective atomic number (Z_eff). Of the four brands investigated, Rider provides superior secondary shielding performance. Concerning potential retrospective dosimetry the effective atomic number of the glass samples are comparable with that of the commercial thermoluminescence (TL) dosimeter TLD-200. At high doses, the TL yields are sufficient to provide for retrospective accident dosimetry.     

Micromechanical analysis of fibrous piezoelectric composites with imperfectly bonded adherence

In this work, two-phase parallel fiber-reinforced periodic piezoelectric composites are considered wherein the constituents exhibit transverse isotropy and the cells have different configurations. Mechanical imperfect contact at the interface of the piezoelectric composites is studied via linear spring model. The statement of the problem for two-phase piezoelectric composites with mechanical imperfect contact is given. The local problems are formulated by means of the asymptotic homogenization method, and their solutions are found using complex variable theory. Analytical formulae are obtained for the effective properties of the composites with spring imperfect type of contact and different rhombic cells. Using the concept of a representative volume element (RVE), a finite element model is created, which combines the angular distribution of fibers and imperfect contact conditions (spring type) between the phases. Periodic boundary conditions are applied to the RVE, so that effective material properties can be derived. The fibers are distributed in such a way that the microstructure is characterized by a rhombic cell. The presented numerical homogenization technique is validated by comparing results with theoretical approach reported in the literature. Some studies of particular cases, numerical examples, and comparisons between the two aforementioned methods with other theoretical results illustrate that the model is efficient for the analysis of composites with presence of rhombic cells and the aforementioned imperfect contact.     

Development of surface plasmon resonance-based sensor for detection of silver nanoparticles in food and the environment

Silver nanoparticles are recognized as effective antimicrobial agents and have been implemented in various consumer products including washing machines, refrigerators, clothing, medical devices, and food packaging. Alongside the silver nanoparticles benefits, their novel properties have raised concerns about possible adverse effects on biological systems. To protect consumer's health and the environment, efficient monitoring of silver nanoparticles needs to be established. Here, we present the development of human metallothionein (MT) based surface plasmon resonance (SPR) sensor for rapid detection of nanosilver. Incorporation of human metallothionein 1A to the sensor surface enables screening for potentially biologically active silver nanoparticles at parts per billion sensitivity. Other protein ligands were also tested for binding capacity of the nanosilver and were found to be inferior to the metallothionein. The biosensor has been characterized in terms of selectivity and sensitivity towards different types of silver nanoparticles and applied in measurements of real-life samples-such as fresh vegetables and river water. Our findings suggest that human MT1-based SPR sensor has the potential to be utilized as a routine screening method for silver nanoparticles, that can provide rapid and automated analysis dedicated to environmental and food safety monitoring.     

Preconcentration and detection of chlorinated organic compounds and benzene

Remote and automated detection of organic compounds in subsurface aquifers is crucial to superfund monitoring and environmental remediation. Current monitoring techniques use expensive laboratory instruments and trained personnel. The use of a filled tubular preconcentrator combined with a chemicapacitive detector array presents an attractive option for the unattended monitoring of these compounds. Five preconcentrator materials were exposed to common target compounds of subsurface remediation projects (1,1,2-trichloroethane, trichloroethylene, t-1,2-dichloroethylene, benzene, and perchloroethylene). Rapid heating of the tube caused the collected, concentrated effluent to pass over the surface of a chemicapacitive detector array coated with four different sorbent polymers. A system containing a porous ladder polymer and the sensor array was subsequently used to sample the analytes injected onto sand in a laboratory test, simulating a subsurface environment. With extended collection times, effective detection limits of 5 ± 3 ppbV for 1,1,2-trichloroethane and 145 ± 60 ppbV for benzene were achieved. Effects of the preconcentrator material structure, the collection time, and sensor material on the system performance were observed. The resultant system presents a solution for remote, periodic monitoring of chlorinated organic compounds and other volatile organic compounds in a soil matrix.     

New indoles from the roots of Brassica rapa ssp. campestris

Two new indoles, 2-C-β-D-glucopyranosyl-1-methoxyindole-3-acetonitrile (1) and 6-hydroxy-1-methylindole3-acetonitrile (2), along with two known indoles [caulilexin C (3) and arvelexin (4)], were isolated from turnip roots (Brassica rapa ssp. campestris L.). The structures of the compounds were established on the basis of NMR, FAB-MS, and IR spectroscopic data.