24,049 research outputs found
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Mechanism of the electrochemical reduction of benzyl chlorides catalysed by Co(salen)
No full textThe electrochemical reduction of benzyl and 4-(trifluoromethyl)benzyl chlorides catalyzed by Co(salen) (H2salen = N,N’-bis(salicylidene)-ethane-1,2-diamine was studied in acetonitrile. Electrogenerated Co(I)(salen) reacts with the halide to give an organocobalt(III) complex. Further one-electron reduction of the latter yields an unstable intermediate that undergoes rapid decomposition by cleavage of the Co-C bond. The mechanism of bond breaking in the one-electron-reduced organocobalt(II) complex was investigated. The results of preparative electrolysis on solutions containing Co(salen) and benzyl chloride, performed under different experimental conditions, in particular in the presence of radical or carbanion scavengers, indicate hemolytic cleavage of the Co-C bond
Role of proton transfer in the electrochemical reduction mechanism of salicylideneaniline
No full textThe electrochemical reduction mechanism of salicylideneaniline has been investigated by cyclic voltammetry, controlled-potential electrolysis and coulometry. The main reduction product, characterised by HPLC, IR, NMR and X-ray diffractometry, is an anionic dimer, present in two diastereoisomeric forms, together with the conjugate base of the substrate. Kinetic analysis of the voltammetric results has allowed the electrode reaction mechanism to be fully characterised, showing in particular that the rate-determining step is the coupling between two anionic radicals, promoted by intramolecular H-bridging
Solubility and electrochemical determination of CO2 in some dipolar aprotic solvents
No full textThe solubility of CO2 in some solvents of electrochemical interest was measured both as a function of its partial pressure and as a function of temperature. Henry constants determined at 298.15 K are reported for DMF, AN, DMSO and THF. The solubility of CO2 in these solvents is also reported at various temperatures in the range -10 to 25 °C (20 to 50 °C for DMSO). The Gibbs energy, enthalpy and entropy of solution at 298.15 K and 1 atm partial pressure of CO2 were estimated from the temperature dependence of the solubility. The effect of base electrolytes on the solubility of CO2 was also investigated. Voltammetric investigations of CO2 reduction showed that, in spite of the large dependence of the peak potential on the nature of the electrode material, the solvent and the background electrolyte, the peak current is proportional to the CO2 concentration, thus providing a means of quantitative CO2 determination
Reprint of “Electrochemical reduction of organic bromides in 1-butyl-3-methylimidazolium tetrafluoroborate”
No full textThe electrochemical reduction of a series of aliphatic and aromatic bromides on glassy carbon, silver and copper electrodes has been investigated by cyclic voltammetry in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm]BF4). As in polar aprotic solvents, reductive cleavage of aromatic bromides occurs by a stepwise mechanism with the formation of a transient radical anion. In contrast, concerted electron transfer/bond rupture is the preferred reaction pathway for aliphatic bromides. Both Ag and Cu show remarkable electrocatalytic activities for the activation of the carbon-bromine bond, but the catalytic effect depends on reaction mechanism and molecular structure of RBr. Catalysis is high when reduction occurs by a concerted dissociative electron transfer pathway, which is the case of alkyl bromides. When instead a stepwise mechanism is preferred, i.e., the case of all aromatic bromides, catalysis strongly decreases with the ability of the molecule to delocalize the incoming negative charge. For example, the high positive shift of peak potential (> 0.7 V) observed for bromobenzene on Ag decreases to < 0.1 V for 4-bromobenzonitrile and < 0.02 V for 9-bromoanthracene.Overall, [BMIm]BF4 behaves like molecular solvents such as acetonitrile and dimethylformamide but, in general, both Ag and Cu are less active in the ionic liquid than in polar aprotic solvents
Language Change and SA-OT: The case of sentential negation
No full textSimulated Annealing for Optimality Theory (SA-OT) updates Optimality Theory by adding a model of performance to a theory of linguistic competence. Our aim is to show that SA-OT can contribute to language change simulations. Performance "errors" are considered to be one of the causes of variation and change. We have chosen to model the evolution of sentential negation (SN). The descriptive background adopts Jespersen's Cycle, according to which the evolution of sentential negation follows three main stages (1. pre-verbal, 2. discontinuous, and 3. post-verbal). Therefore, we advance a novel model for SN, based on SA-OT. It reproduces the three pure and the two observed mixed stages, whereas it correctly predicts the lack of an intermediate stage between 3 and 1. The success of the approach corroborates the computational, performance-based approach to the data. Finally, we employ the iterated learning paradigm to reproduce historical changes in a "simulated corpus study". This enterprise turns out to be more difficult than one would naively believe.Appeared open access as: Computational Linguistics in the Netherlands Journal (CLIN), vol. 1 (2011), pp. 21-40, and is available at http://www.clinjournal.org/sites/default/files/Lopopolo.pdfA. Lopopolo and Biró, T., “Language Change and SA-OT. The case of sentential negation”, Computational Linguistics in the Netherlands Journal, vol. 1, pp. 21-40, 2011.Peer Reviewe
Electrochemical reduction and carboxylation of halobenzophenones
No full textThe electrochemical reduction of a series of halogenated benzophenones X-C6H4COC6H4-Y( 1) was studied in aprotic solvents, in the absence and presence of CO2, by cyclic voltammetry (CV) and controlled-potential electrolysis. The mechanism of electroreduction in dimethylformamide (DMF) has been investigated in some detail. Most of the compounds undergo reductive carbon-halogen bond cleavage in the time window of CV. The radical anions derived from difluorobenzophenones (X = Y = 4-F;
X = 2-F, Y = 4-F) as well as from the 3-chloro derivative are quite stable with a cleavage rate constant (kc)of the order of 0.01 s-1 or less. With 4-chloro-, 2-chloro-, 4,4'-dichloro- and 2,4'-dichorobenzophenones, kc of 1 radical anion has values in the range 4 - 254 s-1 in DMF. In the presence of CO2 all radical anions react quite rapidly with CO2, carboxylation of 1 radical anion being much faster than dehalogenation. Controlled-potential electrolyses were carried out in DMF, MeCN and N-methyl-2-pyrrolidinone (NMP) in an
undivided cell using a compact graphite cathode and an aluminium sacrificial anode. The principal product under these conditions was always the a-hydroxyacid X-C6H4C(OH)(CO2H)C6H4-Y. In NMP under 1 atm of CO2, acid yields around 90% were obtained except in the case of 2-chloro- and 2,4'-dichlorobenzophenone, where acid yields of 58 and 68% were obtained, respectively
Homogeneous electron transfer catalysis in the electrochemical carboxylation of arylethyl chlorides
No full textThe electrochemical carboxylation of arylethyl chlorides (ArCH(CH3)Cl; Ar = 4-biphenyl (1), 6-methoxy-2-naphthyl (2) and 4-isobutylphenyl (3)) catalysed either by nickel(I) Schiff base complexes (NiI(L)) or by radical anions (D•-) derived from aromatic esters has been investigated in acetonitrile. Controlled-potential electrolyses of CO2-saturated CH3CN solutions containing 1-2 mM catalyst and five- to ten-fold excess of arylethyl chloride (RCl) resulted in the formation of a mixture of the corresponding 2-arylpropanoic acid (RCO2H) and arylethane (RH). The yield of the acid was strongly dependent on the standard potential of the catalyst (E°cat), increasing with decreasing E°cat. The mechanism of the catalytic process has been examined. Both types of catalyst follow a reaction mechanism mainly based on electron transfer reactions. In the first step of the electrocatalytic process, the halide reacts with the reduced form of the catalyst, NiI(L) or D•-, to give an arylethyl radical. Further reduction of the radical to the corresponding carbanion is followed by electrocarboxylation in competition with protonation by residual water. The yield of the carboxylic acid is ruled by the ease of reduction of the arylethyl radical. Analysis of the whole set of data obtained for the chlorides 1-3 under different experimental conditions has shown that the RCO2H yield correlates well with the difference between the standard potentials of the arylethyl radical (R•) and catalyst (EoR•/R – E°cat). It became evident from such a correlation that efficient redox catalysis requires the use of a catalyst couple with an E°cat value about 0.4-0.5 V more negative than E°R•/R-
Compared selectivities of redox-catalyzed and direct electrochemical processes Part 2. Reactions in which product selection involves competition between dimerization and deactivation followed by further reduction (or oxidation)
No full textPossible changes in selectivity between redox-catalyzed processes and direct electrochemical reactions are discussed for a typical reaction scheme where product selection involves competition between a dimerization step and a reduction (or oxidation) pathway in which the reductant (or oxidant) is the catalyst on the one hand and the intermediate resulting from the first electron transfer on the other. This second reduction (or oxidation) pathway may or may not be controlled by the transformation of the first electron transfer intermediate into a second intermediate that undergoes a second electron transfer. In the former case, changes in selectivity between the two types of electrolysis conditions arise solely from the space dependence of the reactant and intermediate concentrations. They usaually favor the reduction (or oxidation) pathway in a redox-catalysed process rather than the direct reaction. In the converse situation, where the transformation of the first electron transfer intermediate is reversible and acts as a pre-equilibrium to the second electron transfer, one source of possible changes in selectivity also results from space depenence of the reactant and intermediate concentrations. However, it tends to play an opposite role, favoring the reduction (or oxidation) pathway in the direct reaction rather than the redox-catalyzed process. This effect is amplified if, as is usually the case, the catalyst is a weaker reductant (or oxidant) than the first electron transfer intermediate of the direct electrochemical reaction
Hand Hygiene Compliance and Its Associated Factors Among Health Care Workers at Mogadishu Somali Turkiye Recep Tayyip Erdoğan Training and Research in a Tertiary Care Hospital
No full textSuad Abdikarim Isse,1 Ahmet Doğan,2 Tigad Abdisad Ali,1 Jabir Abdullahi Wehlie,3 Abdirahim Ali Adam,4 Hüsna Öztürk5 1Department of Infectıon Preventıon Control, Mogadıshu Somalı Turkıye Recep Tayyıp Erdogan Traınıng and Research Hospıtal, Mogadishu, Somalia; 2Department of Infectious Diseases and Clinical Microbiology, Abant Izzet Baysal University Faculty of Medicine, Bolu, Turkiye; 3Department of Dermatology, New Vision Hospital, Mogadishu, Somalia; 4Department of Infectious Diseases and Clinical Microbiology, Mogadishu-Somalia-Turkiye Recep Tayyip Erdoğan Training and Research Hospital, Mogadishu, Somalia; 5Department of Infectious Control Nurse Istanbul Koşuyolu Yüksek İhtisas Eğitim ve Araştırma Hastanesi, Istanbul, TurkiyeCorrespondence: Suad Abdikarim Isse; Tigad Abdisad Ali, Email [email protected]; [email protected]: Hand hygiene is a critical preventive measure for controlling infections, particularly in underdeveloped nations.Materials and Methods: A cross-sectional study was conducted in a hospital in Mogadishu, Somalia, from January to March 2024. This study aimed to assess compliance with hand hygiene practices and related factors among healthcare professionals.Results: The study population comprised 52% men and 47.3% women. Most participants held bachelor’s degrees, with the majority being nurses or midwives. A significant proportion had over five years of work experience. Almost all participants were knowledgeable about hand hygiene. Most reported cleaning and drying their hands before, during, and after contact with bodily fluids during aseptic procedures. Age, gender, educational status, marriage, working experience, type of occupation, receiving hand hygiene training and knowledge, and having the availability of water, soap, alcohol, and gloves significantly affected the overall uptake of infection control measures in Mogadishu (p< 0.05).Conclusion: The findings highlight an urgent need for targeted interventions to enhance hand hygiene practices in Somalia. Addressing training gaps and resource shortages is crucial for reducing infection rates and safeguarding patient health in this high-risk setting.Keywords: hand hygiene compliance, healthcare workers, Mogadishu, Somalia, infection contro
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