Mass spectrometric identification and characterization of antimony complexes with ribose-containing biomolecules and an RNA oligomer

Mass spectrometric techniques have been used to study the interaction of inorganic Sb(V) with biomolecules containing a ribose or deoxyribose moiety. Electrospray (ES) mass spectra of reaction mixtures containing inorganic Sb(V) and one of several biomolecules (adenosine, cytidine, guanosine, uridine, adenosine-5′-monophosphate, adenosine-3′,5′-cyclic monophosphate, ribose, or 2′-deoxyadenosine) afforded high-mass antimony-containing ions corresponding to Sb(V)–biomolecule complexes of stoichiometry 1:1, 1:2, or 1:3. The complexes were characterized by collision-induced dissociation (CID) tandem mass spectrometry (MS) using ion-trap multistage MS. The CID results revealed that Sb(V) binds to the ribose or deoxyribose moiety. Structures are proposed for the Sb–biomolecule complexes. Analysis of the reaction mixtures by reversed-phase chromatography coupled on-line to either inductively coupled plasma (ICP) MS or ES–MS showed that in solution Sb(V) forms complexes with all the analyzed biomolecules with vicinal cis hydroxyl groups. Evidence (from size-exclusion chromatography ICP–MS and direct infusion ES–MS) of complexation of Sb(V) with an RNA oligomer, but not with a DNA oligomer, supports the suggestion that the presence of vicinal cis hydroxyl groups is critical for complexation to occur. This is the first direct evidence of complexation of Sb(V) with RNA. Results obtained by studying the effect of changing reaction conditions, i.e. pH, reaction time, and Sb/biomolecule molar ratio, on the extent of Sb–biomolecule formation suggest the reaction may be of physiological importance. Selected reaction monitoring (SRM) and precursor-ion-scanning tandem MS were investigated to determine their potential to detect trace levels of the Sb–biomolecule complexes in biological samples. Application of SRM MS–MS in combination with high-performance liquid chromatography enabled successful detection of an Sb–adenosine complex that had been spiked into a complex biological matrix (liver homogenate).Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Identification of the novel thio-arsenosugars DMThioAsSugarCarboxyl, DMThioAsSugarCarbamate and DMThioAsSugarAdenine in extracts of giant clam tissues by high-performance liquid chromatography online with electrospray tandem mass spectrometry

Recently, the identification of four thio-arsenosugars in extracts of marine samples was reported. The biosynthesis of these arsenic species is most likely closely related to the well known oxo-arsenosugars. Due to their symbiotic algae giant clams contain oxo-arsenosugars with Carboxyl-, Carbamate- and Adenine-aglycone in significant amounts. Now we provide evidence for the presence of the thio analogues of these three arsenosugars in tissue extracts of the giant clams Tridacna maxima and Tridacna derasa. Anion-exchange high-performance liquid chromatography (HPLC) online with electrospray tandem mass spectrometry was applied for the identification of the thio-arsenosugars and the indirect quantification via their oxo analogues.     

High‐density polyethylene layered silicate nanocomposites: Effect of mechanical stretching on the crystal‐to‐crystal transformations,morphology, and extent of exfoliation

High‐density polyethylene/clay nanocomposites were elongated until breakage to investigate the effect of the mechanical stretching on the crystal‐to‐crystal transformations and their morphology. Crystalline transformations of the polymer matrix were studied via Fourier transform infrared spectroscopy, differential scanning calorimetry, and X‐ray diffraction measurements. It was concluded that the stress‐induced crystal‐to‐crystal transformations from orthorhombic structures to monoclinic and pseudohexagonal structures as well as the back‐transformation during relaxation were hindered by the presence of the clay. X‐ray diffraction studies on stretched samples showed that the mechanical stretching led from an intercalated structure to an almost exfoliated structure. These findings agreed with scanning electron micrographs, in which the beneficial effect of stretching on the exfoliation of the clay was evident. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 914–924, 2006     

Characterization of changes induced by ageing to the microstructure of pure cellulose paper by use of a gravimetric water vapour adsorption technique

The changes induced to paper microstructure by accelerated ageing were studied using an automated gravimetric technique based on water vapour adsorption. The technique can be used especially in applications involving the adsorption and desorption of water, such as paper recycling, hornification, ageing and aqueous conservation treatments. The logistics for the calculation of the specific surface area of the examined samples are presented, and the f-plot technique was applied for the visualization and interpretation of the results. These indicated that ageing reduced the adsorption and the swelling capacity of the paper, resulting in a more compact structure, increasing crystallinity and promoting hornification.     

Non-dentable sets in Banach spaces with separable dual

A non-RNP Banach spaceE is constructed such thatE ^* is separable and the RNP is equivalent to the PCP on the subsets ofE.     

A universal building block for the approximate analysis of a shared buffer ATM switch architecture

A universal analytic approximation is proposed for the performance analysis of a general queueing model of a shared buffer ATM switch architecture with bursty arrivals. The forms of the joint, aggregate and marginal state probabilities are characterised via entropy maximisation. As an application, a continuous-time maximum entropy (ME) solution is implemented at equilibrium by assuming that the arrival process to each port of the ATM switch is modelled by a Compound Poisson Process (CPP) with geometrically distributed batches. Consequently, efficientz-transform-type recursive expressions of low computational cost are derived. Validation tests against simulation show that the ME approximation is credible with a very good error-level. Moreover, performance bounds for the mean queue length and cell-loss probability at each output port are experimentally defined over those generated by Interrupted Poisson Processes (IPPs) having the same first two interarrival-time moments.This work is sponsored by the Science and Engineering Research Council (SERC), UK, under grants GR/F 29271 and GR/H 18609.     

Hereditarily indecomposable Banach algebras of diagonal operators

We provide a characterization of the Banach spaces X with a Schauder basis (e _n ) _n∈ℕ which have the property that the dual space X* is naturally isomorphic to the space L _diag(X) of diagonal operators with respect to (e _n ) _n∈ℕ. We also construct a Hereditarily Indecomposable Banach space $ \mathfrak{X} $ \mathfrak{X} _D with a Schauder basis (e _n ) _n∈ℕ such that $ \mathfrak{X} $ \mathfrak{X} *_D is isometric to L _diag($ \mathfrak{X} $ \mathfrak{X} _D) with these Banach algebras being Hereditarily Indecomposable. Finally, we show that every T ∈ L _diag($ \mathfrak{X} $ \mathfrak{X} _D) is of the form T = λI + K, where K is a compact operator.     

A Fuzzy Multi-criteria Outranking Approach in Support of Business Angels’ Decision-Analysis Process for the Assessment of Companies as Investment Opportunities

In this paper, a multi-criteria method is presented for the evaluation and ranking of a selected set of companies as investment opportunities in aid of the relevant decision-analysis process of business angels. The multi-criteria methodology is based on the PROMETHEE method, which is further extended to deal with fuzzy input data in order to address the data imprecision and uncertainty of the decision process. The paper concludes by suggesting a web-based system implementation of the proposed methodology, which will significantly enhance modern business angels networks.     

Pattern-recognition system,designed on GPU,for discriminating between injured normal and pathological knee cartilage

The aim was to design a pattern-recognition (PR) system for discriminating between normal and pathological knee articular cartilage of the medial femoral (MFC) and tibial condyles (MTC). The data set comprised segmented regions of interest (ROIs) from coronal and sagittal 3-T magnetic resonance images of the MFC and MTC cartilage of young patients, 28 with abnormality-free knee and 16 with pathological findings. The PR system was designed employing the probabilistic neural network classifier, textural features from the segmented ROIs and the leave-one-out evaluation method, while the PR system's precision to “unseen” data was assessed by employing the external cross-validation method. Optimal system design was accomplished on a consumer graphics processing unit (GPU) using Compute Unified Device Architecture parallel programming. PR system design on the GPU required about 3.5 min against 15 h on a CPU-based system. Highest classification accuracies for the MFC and MTC cartilages were 93.2% and 95.5%, and accuracies to “unseen” data were 89% and 86%, respectively. The proposed PR system is housed in a PC, equipped with a consumer GPU, and it may be easily retrained when new verified data are incorporated in its repository and may be of value as a second-opinion tool in a clinical environment.