Interaction of molecular nitrogen with vanadium oxide in the absence and presence of water vapor at room temperature: Near-ambient pressure XPS.

Interactions of N2 at oxide surfaces are important for understanding electrocatalytic nitrogen reduction reaction (NRR) mechanisms. Interactions of N2 at the polycrystalline vanadium oxide/vapor interface were monitored at room temperature and total pressures up to 10-1 Torr using Near-Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS). The oxide film was predominantly V(IV), with V(III) and V(V) components. XPS spectra were acquired in environments of both pure N2 and equal pressures of N2 and H2O vapor. In pure N2, broad, partially resolved N1s features were observed at binding energies of 401.0 and 398.7 eV, with a relative intensity of ∼3:1, respectively. These features remained upon subsequent pumpdown to 10-9 Torr. The observed maximum N surface coverage was ∼1.5 × 1013 cm-2-a fraction of a monolayer. In the presence of equal pressures of H2O, the adsorbed N intensity at 10-1 Torr is ∼25% of that observed in the absence of H2O. The formation of molecularly adsorbed H2O was also observed. Density functional theory-based calculations suggest favorable absorption energies for N2 bonding to both V(IV) and V(III) cation sites but less so for V(V) sites. Hartree-Fock-based cluster calculations for N2-V end-on adsorption show that experimental XPS doublet features are consistent with the calculated shake-up and normal, final ionic configurations for N2 end-on bonding to V(III) sites but not V(IV) sites. The XPS spectra of vanadium oxide transferred in situ between electrochemical and UHV environments indicate that the oxide surfaces studied here are stable upon exposure to the electrolyte under NRR-relevant conditions.

Photoinduced charge separation in an oligophenylenevinylene-based Hamilton-type receptor supramolecularly associating two C60-barbiturate guests.

The supramolecular association of an oligophenylene-vinylene (OPV)-based Hamilton-type receptor 1 with C60-barbiturate 2, via six hydrogen bonds per OPV terminal, forming C60/OPV/C60 complex 3 is presented. The particular host-guest motif expressed in 3 ensures strong interactions between the discrete components of the complex based on the multiple hydrogen bonding interactions as conveyed by an association constant greater than 10(5) M(-1). Furthermore, femto- and nano-second transient absorption studies disclose photoinduced charge separation from (1)OPV* to C60 within 9.4 ps. The observed ultrafast charge separation phenomena in the C60/OPV/C60 complex open up wide avenues toward the efficient construction of new materials for optoelectronic and solar cell applications.

Biodegradation of ballast tank coating investigated by impedance spectroscopy and microscopy.

This research paper addresses the biodegradation process for ballast tank coatings in marine environments. As part of this new approach, a commercially available ballast tank coating was exposed to bacteria obtained from a culture collection and to a natural bacterial community isolated from a real ballast tank. The natural community was chosen to explore the interaction of natural biofilms with the coating, an aspect, which is not covered in standard procedures. It is shown that biological activity significantly affects the coating properties. Micro-cracks and holes have been identified using AFM. Acidic bacteria generated holes with 0.2-0.9 µm in depth and 4-9 µm in width. Whereas the natural community additionally caused cracks of 2-8 µm in depth and 1 µm in length. The overall effect of this degradation was examined using the EIS technique. However, the bacterial affected coatings (exposed to acid producing bacteria and a natural community) show a decrease in corrosion resistance. Impedance IZI values decreased over time from 1.18 × 10(9) to 1.87 × 10(7) Ω for acidic bacteria and from 1.71 × 10(9) to 2.24 × 10(7) Ω for the natural community, indicating a clear loss in coating resistance over time. It is also revealed that the coating corrosion resistance declines after 40 days of exposure for the natural community, leading to the formation of blisters. Bacterial settling could be linked to some specific biofilm patterns affecting different types of coating attack. It can be concluded that it is necessary to include natural communities in coating degradation studies to identify possible degradation mechanisms and the severity of the attack over time.

Electronic energy harvesting multi BODIPY-zinc porphyrin dyads accommodating fullerene as photosynthetic composite of antenna-reaction center.

Efficient electronic energy transfer (EET) in the newly synthesized dyads comprised of zinc porphyrin covalently linked to one, two or four numbers of boron dipyrrin (BDP) entities is investigated. Both steady-state and time-resolved emission as well as transient absorption studies revealed occurrence of efficient singlet-singlet energy transfer from BDP to zinc porphyrin with the time scale ranging between 28 and 48 ps. A decrease in time constants for energy transfer with increasing the number of BDP units is observed revealing better antenna effect of dyads bearing higher number of boron dipyrrin entities. Further, supramolecular triads to mimic the 'antenna-reaction center' functionality of photosynthetic reaction center have been successfully constructed by coordinating fulleropyrrolidine appended with an imidazole ligand to the zinc porphyrin. The structural integrity of the supramolecular triads was arrived by optical, computational and electrochemical studies. Free energy calculations revealed possibility of photoinduced electron transfer from singlet excited zinc porphyrin to fullerene, and the preliminary transient absorption studies involving pump-probe technique are supportive of occurrence of electron transfer from (1)ZnP* to fullerene in the supramolecular triads.

The bile acid deoxycholic acid has a non-linear dose response for DNA damage and possibly NF-kappaB activation in oesophageal cells, with a mechanism of action involving ROS.

Deoxycholic acid (DCA) is a secondary bile acid implicated in various cancers of the gastrointestinal (GI) tract. In oesophageal adenocarcinoma, DCA is believed to contribute to carcinogenesis during reflux where stomach contents enter the lower oesophagus. It is imperative that we understand the mechanisms whereby oesophageal carcinogens function in order that therapeutic options may be developed. We have previously shown that DCA can damage chromosomes and does so through its generation of reactive oxygen species (ROS). We show here, after detailed experiments, that DCA appears to have a non-linear dose response for DNA damage. DCA induces DNA damage (as measured by the micronucleus assay) at doses of 100 microM and higher in oesophageal OE33 cells, but fails to induce such DNA damage below this cut-off dose. We also show that in terms of NF-kappaB activation (as measured by up-regulation of two NF-kappaB target genes) by DCA, a similar dose response is observed. This dose-response data may be important clinically as DCA exposure to the oesophagus may be used as a way to identify the 10% of Barrett's oesophagus patients currently progressing to cancer from the 90% of patients who do not progress. Only quantitative studies measuring DCA concentrations in refluxates correlated with histological progression will answer this question. We further show here that ROS are behind DCAs ability to activate NF-kappaB as antioxidants (epigallocatechin gallate, resveratrol and vitamin C) abrogate DCAs ability to up-regulate NF-kappaB-controlled genes. In conclusion, low doses of DCA appear to be less biologically significant in vitro. If this were to be confirmed in vivo, it might suggest that reflux patients with low DCA concentrations may be at a lower risk of cancer progression compared to patients with high levels of DCA in their refluxate. Either way, antioxidant supplementation may possibly help prevent the deleterious effects of DCA in the whole GI tract.

Porphyrinoid rotaxanes: building a mechanical picket fence.

Building on recent progress in the synthesis of functional porphyrins for a range of applications using the Cu-mediated azide-alkyne cycloaddition (CuAAC) reaction, we describe the active template CuAAC synthesis of interlocked triazole functionalised porphyrinoids in excellent yield. By synthesising interlocked analogues of previously studied porphyrin-corrole conjugates, we demonstrate that this approach gives access to rotaxanes in which the detailed electronic properties of the axle component are unchanged but whose steric properties are transformed by the mechanical "picket fence" provided by the threaded rings. Our results suggest that interlocked functionalised porphyrins, readily available using the AT-CuAAC approach, are sterically hindered scaffolds for the development of new catalysts and materials.

Oligothiophene/graphene supramolecular ensembles managing light induced processes: preparation, characterization, and femtosecond transient absorption studies leading to charge-separation.

Advances in organic synthetic chemistry combined with the exceptional electronic properties of carbon allotropes, particularly graphene, is the basis used to design and fabricate novel electron donor-acceptor ensembles with desired properties for technological applications. Thiophene-based materials, which are mainly thiophene-containing polymers, are known for their notable electronic properties. In this frame moving from polymer to oligomer forms, new fundamental information would help for a better understanding of their electrochemical and photophysical properties. Furthermore, a successful combination of their electronic properties with those of graphene is a challenging goal. In this study, two oligothiophene compounds, which consist of three and nine thiophene-rings and are abbreviated 3T and 9T, respectively, were synthesized and noncovalently associated with liquid phase exfoliated few-layered graphene sheets (abbreviated eG), thus forming donor-acceptor 3T/eG and 9T/eG nanoensembes. Markedly, intra-ensemble electronic interactions between the two components in the ground and excited states were evaluated with the aid of UV-Vis and photoluminescence spectroscopy. Furthermore, redox assays revealed the one-electron oxidation of 3T accompanied by one-electron reduction due to eG in 3T/eG, whereas there were two reversible one-electron oxidations of 9T accompanied by one-electron reduction of eG9T/eG. The electrochemical band gap for the 3T/eG and 9T/eG ensembles were calculated and verified, in which the negative free-energy change for the charge-separated state of 3T/eG and 9T/eGvia the singlet excited state of 3T and 9T, respectively, were thermodynamically favorable. Finally, the results of transient pump-probe spectroscopy studies at the femtosecond time scale were supportive of charge transfer type interactions in the 3T/eG and 9T/eG ensembles. The estimated rates for intra-ensemble charge separation were found to be 9.52 × 10(9) s(-1) and 2.2 × 10(11) s(-1), respectively, for 3T/eG and 9T/eG in THF, which reveal moderate to ultrafast photoinduced events in the oligothiophene/graphene supramolecular ensembles.

The first total synthesis of a highly branched arabinofuranosyl hexasaccharide found at the nonreducing termini of mycobacterial arabinogalactan and lipoarabinomannan.

[reaction--see text] The first total synthesis of the arabinofuranosyl hexasaccharide present at the nonreducing termini of mycobacterial arabinogalactan and lipoarabinomannan is reported. The oligosaccharide was prepared as its methyl glycoside via a route that is both highly efficient and convergent. Addition of two beta-D-arabinofuranosyl residues simultaneously in high yield and with excellent stereocontrol was the key step of the synthesis.

A randomised controlled trial of an oral solution of prostaglandin E2 and oral oxytocin used immediately after low amniotomy for induction of labour in the presence of a favourable cervix.

A randomised controlled trial was carried out in 50 primigravidae and 50 multigravidae to compare the effectiveness in induction of labour after low amniotomy of prostaglandin E2, given as an oral solution, and oxytocin, given as buccal tablets. The results showed that in dosages recommended by the manufacturers, both oxytocic preparations were almost equally effective. With oral oxytocin, once labour had been established and dosage was left to the discretion of the staff, there appeared to be a potentially dangerous tendency to continue giving large doses despite adequate uterine contractions. The authors comment that this was probably the reason why oxytocin-treated multigravidae having normal deliveries within 24 hours had labours significantly shorter on average than those of other successfully induced patients.

Dimethyl azo(bisisobutyrate) and C(60) produce 1,4- and 1, 16-Di(2-carbomethoxy-2-propyl)-1,x-dihydro

Thermal decomposition of dimethyl azo(bisisobutyrate) in a solution containing C(60) produced 1,4- and 1, 16-di(2-carbomethoxy-2-propyl)-1,x-dihydro[60]fullerenes in yields of 21% and 27%, respectively, based on reacted C(60). The structure of this first 1,16-dialkyl-1,16-dihydro[60]fullerene was assigned from (13)C 2D INADEQUATE NMR spectra. The 1,16-isomer has first and second electrochemical reduction potentials shifted positively by 0. 18 V relative to those of the 1,4-isomer. From the close similarity of all spectral, chromatographic, and electrochemical data, the previously unassigned isomer of 1,x-di(2-cyano-2-propyl)-1, x-dihydro[60]fullerene, which was obtained from azo(bisisobutyronitrile) and C(60), is also a 1,16-isomer.

Synthesis and Electrochemical Reactivity of sigma-Bonded and N-Substituted Cobalt Porphycenes.

The first synthesis and characterization of sigma-bonded and N-substituted cobalt porphycenes is reported. The investigated compounds are represented as (Pc)Co(R) and (N-CH(3)OEPc)CoCl, where R is CH(3) or C(6)H(5), Pc is the dianion of 2,3,6,7,12,13,16,17-octaethylporphycene (OEPc), 2,7,12,17-tetrapropylporphycene (TPrPc), or 2,7,12,17-tetraethyl-3,6,13,16-tetramethylporphycene (EtioPc), N-CH(3)OEPc is the monoanion of N-methyl-2,3,6,7,12,13,16,17-octaethylporphycene. Each sigma-bonded (Pc)Co(R) derivative can be reversibly reduced or oxidized by two electrons, but a slow migration of the sigma-bonded R group occurs following electrogeneration of [(Pc)Co(R)](+)()(*)() leading, as a final product, to an N-substituted cobalt(II) porphycene which is also electroactive and undergoes two reductions in PhCN. The singly reduced product of this reaction is formulated as a Co(II) pi-anion radical which undergoes a slow "back-migration" of the CH(3) group to regenerate (OEPc)Co(CH(3)).

Synthesis of carboxyl-reduced analogues related to the Chlamydia-specific Kdo trisaccharide epitope.

The disaccharides allyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->4)-3-deoxy-a lph a-D- manno-2-octulopyranoside (8), allyl O-(3-deoxy-alpha-D-manno-2-octulopyranosyl)-(2-->8)-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosidonate) (24), and allyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->8)-3-deoxy-a lph a-D- manno-2-octulopyranoside (35), and the trisaccharides allyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->8)-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->4)-3-deoxy-a lph a-D-manno-2-octulopyranoside (13) and allyl O-(3-deoxy-alpha-D-manno-2-octulopyranosyl)-(2-->8)-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->4)-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosidonate) (30) were prepared. The ketosidic linkages were formed in good yields and high stereoselectivity by BF3 . Et2O-catalyzed reaction of the per-O-acetylated 3-deoxy-alpha-D-manno-2-octulopyranosyl fluoride derivative (16) with 8-O-SiButMe2 derivatives 19 and 21. Coupling reactions using the Kdo monosaccharide bromide derivative 4 or the alpha-(2-->8)-linked Kdo disaccharide bromide derivatives 9 and 26 were performed under Helferich conditions in MeCN or MeNO2, respectively. The disaccharide halides were prepared in good overall yields starting from the readily available allyl beta-glycoside of Kdo. The deprotected oligosaccharides correspond to the genus-specific lipopolysaccharide epitope of Chlamydia and part structures thereof, containing the carboxyl-reduced Kdo-residues at the distal and proximal position of the Kdo trisaccharide epitope, respectively.

Endoscopic stapling of post-laryngectomy neopharyngeal anterior diverticulum.

An anterior neopharyngeal diverticulum is a recognized cause of dysphagia following laryngectomy. It is easily treated by endoscopic stapling.

Unusual presentation of acute pancreatitis: an irreducible inguinoscrotal swelling mimicking a strangulated hernia.

We report an unusual presentation of acute pancreatitis as a tender, irreducible, inguinoscrotal swelling mimicking a strangulated hernia. Lack of abdominal symptoms or signs can lead to misdiagnosis and unnecessary surgery.

Antiproliferative effects of calcitonin gene-related peptide in aortic and pulmonary artery smooth muscle cells.

Pulmonary hypertension is characterized by vascular remodeling involving smooth muscle cell proliferation and migration. Calcitonin gene-related peptide (CGRP) and nitric oxide (NO) are potent vasodilators, and the inhibition of aortic smooth muscle cell (ASMC) proliferation by NO has been documented, but less is known about the effects of CGRP. The mechanism by which overexpression of CGRP inhibits proliferation in pulmonary artery smooth muscle cells (PASMC) and ASMC following in vitro transfection by the gene coding for prepro-CGRP was investigated. Increased expression of p53 is known to stimulate p21, which inhibits G(1) cyclin/cdk complexes, thereby inhibiting cell proliferation. We hypothesize that p53 and p21 are involved in the growth inhibitory effect of CGRP. In this study, CGRP was shown to inhibit ASMC and PASMC proliferation. In PASMC transfected with CGRP and exposed to a PKA inhibitor (PKAi), cell proliferation was restored. p53 and p21 expression increased in CGRP-treated cells but decreased in cells treated with CGRP and PKAi. PASMC treated with CGRP and a PKG inhibitor (PKGi) recovered from inhibition of proliferation induced by CGRP. ASMC treated with CGRP and then PKAi or PKGi recovered only when exposed to the PKAi and not PKGi. Although CGRP is thought to act through a cAMP-dependent pathway, cGMP involvement in the response to CGRP has been reported. It is concluded that p53 plays a role in CGRP-induced inhibition of cell proliferation and cAMP/PKA appears to mediate this effect in ASMC and PASMC, whereas cGMP appears to be involved in PASMC proliferation.

Recovery following the South Italian earthquake, November 1980: Two contrasting examples.

Recovery and reconstruction in two communities following the South Itallan earthquake is described and differences are related to factors such as pradisaster development levels, relief decisions made during the emergency phase, the kind of material aid received, local leadership and economic opportunities. The combination of appropriate aid and effective leadership appears to a potent force for recovery.

Recovery following the Gediz earthquake: a study of four villages of western Turkey.

This paper is the result of a social and economic survey of four villages in the Gediz region of South West Anatolia, Turkey, which was undertaken in two phases, October/November 1982 and March/April 1984. The specific aims of this survey were to define what was perceived as recovery in the local social, cultural and economic context and to measure recovery in communities which had suffered different degrees of distress and loss following the earthquake and, consequently, had received different amounts and kinds of assistance from the government. Essentially, therefore, the survey sought to answer the question - how far did the government programme of assistance promote recovery and over what period of time? The implications of such an inquiry concern what constitutes appropriate assistance following earthquake in rural communities. It is hoped that studies of this kind can help to guide decision making of both national governments and international humanitarian organizations on the role of material aid in the process of recovery. This is particularly urgent in view of the fact that preliminary investigations of other small rural and under-developed communities struck by earthquake suggest that material aid may actually preclude recovery in the longer term.