The gamma-ray burst monitor on board the SAX satellite

Summary The anticoincidence lateral shields of the high-energy ((15÷200) keV) detector PDS aboard the SAX satellite will be used to detect celestial gamma-ray bursts. As a gamma-ray burst monitor (GRBM), the shields have a 5σ sensitivity in the (60÷600) keV nominal energy band about 10⁻⁶ erg/cm², and a capability of determining the burst location to an accuracy of a few tenths of degree to several degrees, depending on burst direction and strength. The GRBM will be mainly devoted to study the burst time profile with a time resolution down to 0.5 ms. Its expected performances are evaluated by means of Monte Carlo simulations. To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee.     

Coordinated observation of the massive system 4U1700+24=HD154791

Summary We report results from multifrequency observations of the X-ray source 4U1700+24/HD154791. This source was observed simultaneously with the EXOSAT and IUE satellites on March 25, 1985, and it is continuously monitored in the optical band at the Bologna Astronomical Observatory since July 1984. Our observations show source features which are different from those measured during previous observations. The X-ray spectrum is significantly softer than in previous measurements, and much more absorbed; high excitation lines in UV spectra (C IV and N V) have disappeared; the optical spectrum, despite a fairly good photometric stability of the M giant HD154791 in V and B bands also shows differences with respect to previous observations. We discuss our results in the framework of both a binary model and a coronal model. We point out that our observations strengthen the hypothesis that the X-ray emission is due to mass accretion onto a compact object orbiting around the M giant star HD154791. To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee.     

Potts Models in the Continuum. Uniqueness and Exponential Decay in the Restricted Ensembles

In this paper we study a continuum version of the Potts model, where particles are points in ℝ ^d , d≥2, with a spin which may take S≥3 possible values. Particles with different spins repel each other via a Kac pair potential of range γ ⁻¹, γ>0. In mean field, for any inverse temperature β there is a value of the chemical potential λ _β at which S+1 distinct phases coexist. We introduce a restricted ensemble for each mean field pure phase which is defined so that the empirical particles densities are close to the mean field values. Then, in the spirit of the Dobrushin-Shlosman theory (Dobrushin and Shlosman in J. Stat. Phys. 46(5–6):983–1014, 1987), we prove that while the Dobrushin high-temperatures uniqueness condition does not hold, yet a finite size condition is verified for γ small enough which implies uniqueness and exponential decay of correlations. In a second paper (De Masi et al. in Coexistence of ordered and disordered phases in Potts models in the continuum, 2008), we will use such a result to implement the Pirogov-Sinai scheme proving coexistence of S+1 extremal DLR measures.     

Microspheres made of poly(epsilon-caprolactone)-based amphiphilic copolymers: potential in sustained delivery of proteins

Microspheres of amphiphilic multi-block poly(ester-ether)s (PEE)s and poly(ester-ether-amide)s (PEEA)s based on poly(epsilon-caprolactone) (PCL) were investigated as delivery systems for proteins. The interest was mainly focused on the effect of their molecular structure and composition on the overall properties of the microspheres, encapsulating bovine serum albumin (BSA) as a model protein. PEEs and PEEAs were prepared using a alpha,omega-dihydroxy-terminated PCL macromer (Mn= 2.0 kDa) as a hydrophobic component. Hydrophilic oxyethylene sequences were generated using poly(ethylene oxide)s (PEO)s of different molecular mass (Mn= 300-600 Da) in the case of PEEs, or 4,7,10-trioxa-1,13-tridecanediamine (Trioxy) and PEO150 (Mn= 150 Da) in the case of PEEAs. The copolymers showed a decrease of Tm and crystallinity values as compared with PCL. Within each class of copolymers, the bulk hydrophilicity increased with increasing the number of oxyethylene groups in the chain repeat unit. PEEAs were more hydrophilic than PEEs with a similar number of oxyethylene groups. Discrete spherical particles were prepared by both PEEs and PEEAs and their BSA encapsulation efficiency related to copolymer properties. Interestingly, the insertion of short hydrophilic segments is enough to significantly affect protein distribution inside microspheres and its release profiles, as compared to PCL microspheres. Different degradation rates and mechanisms were observed for copolymer microspheres, mainly depending on the distribution of oxyethylene units along the chain. The results highlight that a fine control over the structural parameters of amphiphilic PCL-based multi-block copolymers is a key factor for their application in the field of protein delivery.     

1,3-dimethylimidazolium-2-carboxylate: the unexpected synthesis of an ionic liquid precursor and carbene-CO2 adduct

1,3-Dimethylimidazolium-2-carboxylate is formed in good yield, rather than the anticipated organic salt, 1,3-dimethylimidazolium methyl carbonate, as the reaction product resulting from both N-alkylation and C-carboxylation of 1-methylimidazole with dimethyl carbonate; the crystal structure of the zwitterion exhibits pi-stacked rings and two-dimensional sheets constructed by hydrogen-bonds from imidazolium-ring hydrogens to the carboxylate group.     

Time-invariant portfolio strategies in structured products with guaranteed minimum equity exposure

We introduce a new exotic option to be used within structured products to address a key disadvantage of standard time-invariant portfolio protection: the well-known cash-lock risk. Our approach suggests enriching the framework by including a threshold in the allocation mechanism so that a guaranteed minimum equity exposure (GMEE) is ensured at any point in time. To be able to offer such a solution still with hard capital protection, we apply an option-based structure with a dynamic allocation logic as underlying. We provide an in-depth analysis of the prices of such new exotic options, assuming a Heston–Vasicek-type financial market model, and compare our results with other options used within structured products. Our approach represents an interesting alternative for investors aiming at downsizing protection via time-invariant portfolio protection strategies, meanwhile being also afraid to experience a cash-lock event triggered by market turmoils.     

Antimicrobial activity of spices essential oils and its effectiveness on mature biofilms of human pathogens

Abstract

The antibacterial activity of Pimpinella anisum L., Cinnamomum zeylanicum, Syzygium aromaticum, and Cuminum cyminum L. essential oils (EOs) against some common pathogenic microorganisms (Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 14990, Enterococcus faecalis ATCC 29212, Streptococcus pyogenes ATCC 1915, Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 27853, Aeromonas hydrophila ATCC 7966, Proteus mirabilis ATCC 10005, Klebsiella pneumoniae ATCC 13883, and Candida albicans ATCC 10231) and their biofilms was studied. The EOs inhibitory effects were evaluated by both Agar Well Diffusion assay and Minimum Inhibitory Concentration (MIC) determination. The most active EOs, cinnamon and cloves, were also tested on 18, 24, 48, 72?hours mature biofilms. Cinnamon and cloves exhibited the best results showing a significant activity against all the tested bacteria. Concerning biofilm, results suggest that Cinnamomum zeylanicum oil may be a useful approach to impair the biofilm produced by the tested Gram-negative bacteria.      

Ocimum campechianum Mill. from Amazonian Ecuador: Chemical Composition and Biological Activities of Extracts and Their Main Constituents (Eugenol and Rosmarinic Acid)

The essential oil (EO), the methanolic (MeOH), and the 70% ethanolic (70% EtOH) extracts obtained from the aerial parts of Ocimum campechianum Mill. (Ecuador) were chemically characterized through gas-chromatography coupled to mass spectrometry detector (GC-MS), high-performance liquid chromatography coupled to diode array-mass spectrometry detectors (HPLC-DAD-MS) and studied for their in vitro biological activity. The radical scavenger activity, performed by spectrophotometric 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, highlighted significant IC₅₀ values for the EO, extracts and their main constituents (eugenol and rosmarinic acid). EO (and eugenol) showed noteworthy activity against Pseudomonas syringae pv. syringae and a moderate effect against clinical Candida strains, with possible synergism in association to fluconazole against the latter microorganisms. The extracts and pure molecules exhibited weak cytotoxic activity against the HaCat cell line and no mutagenicity against Salmonella typhimurium TA98 and TA100 strains, giving indication of safety. Instead, EO showed a weak activity against adenocarcinomic human alveolar basal epithelial cells (A549). The above-mentioned evidence leads us to suggest a potential use of the crude drug, extracts, and EO in cosmetic formulation and food supplements as antioxidant agents. In addition, EO may also have a possible application in plant protection and anti-Candida formulations.     

Structural Determination and Chemical Synthesis of the N-Glycan from the Hyperthermophilic Archaeon Thermococcus kodakarensis

Asparagine-linked protein glycosylations (N-glycosylations) are one of the most abundant post-translational modifications and are essential for various biological phenomena. Herein, we describe the isolation, structural determination, and chemical synthesis of the N-glycan from the hyperthermophilic archaeon Thermococcus kodakarensis. The N-glycan from the organism possesses a unique structure including myo-inositol, which has not been found in previously characterized N-glycans. In this structure, myo-inositol is highly glycosylated and linked with a disaccharide unit through a phosphodiester. The straightforward synthesis of this glycan was accomplished through diastereoselective phosphorylation and phosphodiester construction by S_N2 coupling. Considering the early divergence of hyperthermophilic organisms in evolution, this study can be expected to open the door to approaching the primitive function of glycan modification at the molecular level.