Generation and reactivity of carbon, sulphur and tellurium centred free radicals

Using ESR dimer-radical equilibrium techniques the heat of formation, △Hf⁰, of the pentamethylcyclopentadienyl radical was determined as 7.4 kcal mol⁻¹, and hence SEMeH was calculated to be 37.9 kcal mol⁻¹. It was attempted to determine △Hf⁰ for the pentaethyl- and pentamethoxycarbonylcyclopentadienyl radicals, but this proved unsuccessful. From appearance energy measurements, △Hf⁰ (Pentadienyl) was determined to be 49.6 kcal mol⁻¹ Using photoacoustic calorimetry, the C₃-H bond dissociation energy of penta⁻¹,4-diene and several 3-substituted pentadienes were determined; i.e. for penta⁻¹,4-diene (DH° (C₃-H) = 76.6±0.6 kcal mol⁻¹), 3-methyl- penta⁻¹,4-diene (DH°(C₃-H) = 76.6±0.6 kcal mol⁻¹) and 3-hydroxypenta⁻¹,4-diene (DH°(C₃-H) = 69.0±0.6 kcal mol⁻¹). ESR exchange broadening methods were used to show that SEESR (3-methylpentadienyl) is virtually the same as that of the parent pentadienyl radical, (i.e. 25 kcal mol⁻¹). The 3-hydroxypentadienyl, l-hydroxy-3-methylpentadienyl and l-trimethylsilyloxy-3-methylpentadienyl radicals were generated, but exchange broadening was not observed in the accessible temperature range. Sulphonate esters were examined as a potential source of free radicals. The reaction of simple alkyl alkanesulphonates with photochemically generated trimethyltin radicals in the cavity of an ESR spectrometer gave the corresponding alkanesulphonyl radicals. Good ESR spectra were obtained when sulphonyl radicals, generated from sulphonate esters, were used to form adduct radicals with alkenes of the type CH₂=CHR where R is an electron releasing substituent, (R = OMe, OBuⁿ, SPh, SiME₃). Delocalised radicals were generated from sulphonate esters which contained a terminal alkenyl or alkynyl substituent. For example, the reaction of allyl methanesulphonate with photochemically generated trimethyltin radicals in the cavity of an ESR spectrometer gave good spectra of the allyl radical. The pent-4-ene-1-sulphonyl radical was generated from the corresponding sulphonyl chloride using several different radical initiator systems (tri-n-butyltin hydride, triphenylsilane, hexa-n-butylditin, 9-trimethylstannyl-9,10-dihydroanthracene, copper (II) chloride and tris (triphenylphosphine) ruthenium (II) chloride). The radical was found to cyclise in a predominantly endo-fashion to give 3-chlorotetrahydrothiopyran-1,1-dioxide, the exact proportion of endo- and exo-products depending on the temperature. The hex-5-ene-1-sulphonyl radical was found to give thiepane-1,1- dioxide, also the product of endo-cyclisation. The inclusion of a bulky ring substituent forced the cyclohexenylethanesulphonyl radical to cyclise in the exo-mode to give 2-chloro-9-thiabicyclo[4.3.0]nonane-9,9-dioxide. Dialkyltellurides and dialkylditellurides gave the corresponding alkyl radical on photolysis in the cavity of an ESR spectrometer. For example, diallyltelluride gave good spectra of the allyl radical. Under thermolysis conditions, a nitrosodurene spin trap was employed to observe the trapped alkyl radicals. It is believed that certain of the trapped radicals were tellurium-centred species

Heightened immune response to autocitrullinated porphyromonas gingivalis peptidylarginine deiminase: a potential mechanism for breaching immunologic tolerance in rheumatoid arthritis

Background: Rheumatoid arthritis (RA) is characterised by autoimmunity to citrullinated proteins, and there is increasing epidemiologic evidence linking Porphyromonas gingivalis to RA. P gingivalis is apparently unique among periodontal pathogens in possessing a citrullinating enzyme, peptidylarginine deiminase (PPAD) with the potential to generate antigens driving the autoimmune response. Objectives: To examine the immune response to PPAD in patients with RA, individuals with periodontitis (PD) and controls (without arthritis), confirm PPAD autocitrullination and identify the modified arginine residues. Methods: PPAD and an inactivated mutant (C351A) were cloned and expressed and autocitrullination of both examined by immunoblotting and mass spectrometry. ELISAs using PPAD, C351A and another P gingivalis protein arginine gingipain (RgpB) were developed and antibody reactivities examined in patients with RA (n=80), individuals with PD (n=44) and controls (n=82). Results: Recombinant PPAD was a potent citrullinating enzyme. Antibodies to PPAD, but not to Rgp, were elevated in the RA sera (median 122 U/ml) compared with controls (median 70 U/ml; p<0.05) and PD (median 60 U/ml; p<0.01). Specificity of the anti-peptidyl citrullinated PPAD response was confirmed by the reaction of RA sera with multiple epitopes tested with synthetic citrullinated peptides spanning the PPAD molecule. The elevated antibody response to PPAD was abolished in RA sera if the C351A mutant was used on ELISA. Conclusions: The peptidyl citrulline-specific immune response to PPAD supports the hypothesis that, as a bacterial protein, it might break tolerance in RA, and could be a target for therapy

'Silence bleeds': Hamlet across borders : The Shakespearean Adaptations of Sulayman Al-Bassam

Original article can be found at: http://www.informaworld.com/smpp/title~content=t713734315~db=all Copyright Informa / Taylor and FrancisThis article addresses the writing and performance work of Anglo-Kuwaiti director Sulayman Al-Bassam, tracing the development of his various adaptations of Shakespeare's Hamlet into English and Arabic 'cross-cultural' versions between 2001 and 2007. Al-Bassam's work presents English as a 'language in translation'. His works move from early modern to modern English, from Arabized English to Arabic, from one linguistic and geographical location to another, their forms moulded and remoulded by complex cultural pressures. The study focuses on specific examples from three adaptations to show in practice how in these works English is 'constantly crossed, challenged and contested'Peer reviewedFinal Accepted Versio

Ultra small integrated optical fiber sensing system

This paper introduces a revolutionary way to interrogate optical fiber sensors based on fiber Bragg gratings (FBGs) and to integrate the necessary driving optoelectronic components with the sensor elements. Low-cost optoelectronic chips are used to interrogate the optical fibers, creating a portable dynamic sensing system as an alternative for the traditionally bulky and expensive fiber sensor interrogation units. The possibility to embed these laser and detector chips is demonstrated resulting in an ultra thin flexible optoelectronic package of only 40 µm, provided with an integrated planar fiber pigtail. The result is a fully embedded flexible sensing system with a thickness of only 1 mm, based on a single Vertical-Cavity Surface-Emitting Laser (VCSEL), fiber sensor and photodetector chip. Temperature, strain and electrodynamic shaking tests have been performed on our system, not limited to static read-out measurements but dynamically reconstructing full spectral information datasets

Nonprimate hepaciviruses in domestic horses, United kingdom

Although the origin of hepatitis C virus infections in humans remains undetermined, a close homolog of this virus, termed canine hepacivirus (CHV) and found in respiratory secretions of dogs, provides evidence for a wider distribution of hepaciviruses in mammals. We determined frequencies of active infection among dogs and other mammals in the United Kingdom. Samples from dogs (46 respiratory, 99 plasma, 45 autopsy samples) were CHV negative by PCR. Screening of 362 samples from cats, horses, donkeys, rodents, and pigs identified 3 (2%) positive samples from 142 horses. These samples were genetically divergent from CHV and nonprimate hepaciviruses that horses were infected with during 2012 in New York state, USA. Investigation of infected horses demonstrated nonprimate hepacivirus persistence, high viral loads in plasma (105–107 RNA copies/mL), and liver function test results usually within reference ranges, although several values ranged from high normal to mildly elevated. Disease associations and host range of nonprimate hepaciviruses warrant further investigation

Methane detection scheme based upon the changing optical constants of a zinc oxide/platinum matrix created by a redox reaction and their effect upon surface plasmons

We detect changes in the optical properties of a metal oxide semiconductor (MOS), ZnO, in a multi-thin-film matrix with platinum in the presence of the hydrocarbon gas methane. A limit of detection of 2% by volume with concentrations from 0 to 10% and maximum resolution of 0.15% with concentrations ranging from 30% to 80% at room temperature are demonstrated along with a selective chemical response to methane over carbon dioxide and the other alkane gases. The device yields the equivalent maximum bulk refractive index spectral sensitivity of 1.8 × 105 nm/RIU. This is the first time that the optical properties of MOS have been monitored to detect the presence of a specific gas. This single observation is a significant result, as MOS have a potentially large number of target gases, thus offering a new paradigm for gas sensing using MOSs

Generation of sulphonyl radicals from sulphonate esters

Alkane alkylsulphonates and arylsulphonates are useful sources of sulphonyl radicals on treatment with organotin radicals. EPR spectra of the adduct radicals from CH3SO2 · and alkenes containing donor substituents were observed.</p

Sulphonate esters as sources of sulphonyl radicals; ring-closure reactions of alk-4- and -5-enesulphonyl radicals

Alkyl alkanesulphonates and arenesulphonates were found to be useful sources of sulphonyl radicals, particularly for spectroscopic work, when treated with organotin or organosilyl radicals. Allyl, propynyl and penta-2,4-dienyl methanesulphonates gave, however, allyl, propynyl and pentadienyl radicals, respectively. Sulphonyl radicals generated in this way added efficiently to alk-1-enes with electron-releasing substituents, and the EPR spectra of the adduct radicals were recorded. A variety of radical initiation systems were tried on pent-4-enesulphonyl chloride. The pent-4-enesulphonyl radical cyclised mainly in the endo mode to give the six-membered-ring sulphone. Similarly, the hex-5-enesulphonyl radical cyclised to give thiepane 1,1-dioxide, with a seven-membered ring. The cyclohex-2-enylethanesulphonyl radical cyclised mainly in the exo mode to give 2-chloro-9-thiabicyclo[4.3.0]nonane 9,9-dioxide. The mechanisms of these reactions are discussed.</p

Generation of sulphonyl radicals from sulphonate esters

Alkane alkylsulphonates and arylsulphonates are useful sources of sulphonyl radicals on treatment with organotin radicals. EPR spectra of the adduct radicals from CH3SO2 · and alkenes containing donor substituents were observed.</p