34 research outputs found

    Photoelectrochemical cells based on emeraldine base form of polyaniline

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    Photoelectrochemical cells (PECs) have been fabricated using the emeraldine base form of polyaniline (EB) as a photoactive material and Eu2+/Eu3+ redox couple in methanol as an electrolyte. A PEC with a structure: Glass/ITO/EB/electrolyte/Pt produces an open-circuit voltage (V OC) of -0.132 V and a short-circuit current (I SC) of 0.64 µA cm-2 under 50 mW cm-2 white light illumination from Xe lamp. In an effort to increase the photoresponse, a PEC with a structure: Glass/ITO/EB:Nc-TiO2/Electrolyte/Pt has been devised in which a composite film of EB and nanocrystalline TiO2 (Nc-TiO2) is used as a photoactive material. The cell shows a V OC of -0.205 V and an I SC of 105 µA cm-2 when illuminated under the same conditions

    Synthesis of reaction-adapted zeolites as methanol-to-olefins catalysts with mimics of reaction intermediates as organic structure-directing agents

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    [EN] Catalysis with enzymes and zeolites have in common the presence of well-defined single active sites and pockets/cavities where the reaction transition states can be stabilized by longer-range interactions. We show here that for a complex reaction, such as the conversion of methanol-to-olefins (MTO), it is possible to synthesize reaction-adapted zeolites by using mimics of the key molecular species involved in the MTO mechanism. Effort has focused on the intermediates of the paring mechanism because the paring is less favoured energetically than the side-chain route. All the organic structure-directing agents based on intermediate mimics crystallize cage-based small-pore zeolitic materials, all of them capable of performing the MTO reaction. Among the zeolites obtained, RTH favours the whole reaction steps following the paring route and gives the highest propylene/ethylene ratio compared to traditional CHA-related zeolites (3.07 and 0.86, respectively).Li, C.; Paris, C.; Martínez-Triguero, J.; Boronat Zaragoza, M.; Moliner Marin, M.; Corma Canós, A. (2018). Synthesis of reaction-adapted zeolites as methanol-to-olefins catalysts with mimics of reaction intermediates as organic structure-directing agents. Nature Catalysis. 1(7):547-554. https://doi.org/10.1038/s41929-018-0104-7S54755417Stocker, M. Methanol-to-hydrocarbons: catalytic materials and their behavior. Micro. Mesopor. Mater. 29, 3–48 (1999).Tian, P., Wei, Y., Ye, M. & Liu, Z. Methanol to olefins (MTO): from fundamentals to commercialization. ACS Catal. 5, 1922–1938 (2015).Ilias, S. & Bhan, A. Mechanism of the catalytic conversion of methanol to hydrocarbons. ACS Catal. 3, 18–31 (2013).Olsbye, U. et al. Conversion of methanol to hydrocarbons: how zeolite cavity and pore size controls product selectivity. Angew. Chem. Int. Ed. 24, 5810–5831 (2012).Hemelsoet, K., Van der Mynsbrugge, J., De Wispelaere, K., Waroquier, M. & Van Speybroeck, V. Unraveling the reaction mechanisms governing methanol-to-olefins catalysis by theory and experiment. ChemPhysChem 14, 1526–1545 (2013).Song, W., Haw, J. F., Nicholas, J. B. & Heneghan, C. S. Methylbenzenes are the organic reaction centers for methanol-to-olefin catalysis on HSAPO-34. J. Am. Chem. Soc. 122, 10726–10727 (2000).Arstad, B. & Kolboe, S. The reactivity of molecules trapped within the SAPO-34 cavities in the methanol-to-hydrocarbons reaction. J. Am. Chem. Soc. 123, 8137–8138 (2001).Xu, T. et al. Synthesis of a benzenium ion in a zeolite with use of a catalytic flow reactor. J. Am. Chem. Soc. 120, 4025–4026 (1998).Song, W., Nicholas, J. B., Sassi, A. & Haw, J. F. Synthesis of the heptamethylbenzene cation in zeolite beta: in situ NMR and theory. Catal. Lett. 81, 49–53 (2002).Xu, S. et al. Direct observation of cyclic carbenium ions and their role in the catalytic cycle of the metahnol-to-olefin reaction over chabazite zeolites. Angew. Chem. Int. Ed. 52, 11564–11568 (2013).Chen, J. et al. Elucidating the olefin formation mechanism in the methanol to olefin reaction over AlPO-18 and SAPO-18. Catal. Sci. Tech. 4, 3268–3277 (2014).Haw, J. F. et al. Roles for cyclopentenyl cations in the synthesis of hydrocarbons from methanol on zeolite catalyst HZSM-5. J. Am. Chem. Soc. 122, 4763–4775 (2000).Svelle, S. et al. Conversion of methanol into hydrocarbons over zeolite H-ZSM-5: ethene formation is mechanistically separated from the formation of higher alkenes. J. Am. Chem. Soc. 128, 14770–14771 (2006).Teketel, S., Olsbye, U., Lillerud, K. P., Beato, P. & S., S. Selectivity control through fundamental mechanistic insight in the conversion of methanol to hydrocarbons over zeolites. Micro. Mesopor. Mater. 136, 33–41 (2010).Zhang, M. et al. Methanol conversion on ZSM-22, ZSM-35 and ZSM-5 zeolites: effects of 10-membered ring zeolite structures on methylcyclopentenyl cations and dual cycle mechanism. RSC Adv. 6, 95855–95864 (2016).Sassi, A. et al. Methylbenzene chemistry on zeolite HBeta: multiple insights into methanol-to-olefin catalysis. J. Phys. Chem. B 106, 2294–2303 (2002).Sassi, A., Wildman, M. A. & Haw, J. F. Reactions of butylbenzene isomers on zeolite HBeta: methanol-to-olefins hydrocarbon pool chemistry and secondary reactions of olefins. J. Phys. Chem. B 106, 8768–8773 (2002).Bjørgen, M., Olsbye, U., Petersen, D. & Kolboe, S. The methanol-to-hydrocarbons reaction: insight into the reaction mechanism from [12C]benzene and [13C]methanol coreactions over zeolite H-beta. J. Catal. 221, 1–10 (2004).McCann, D. M. et al. A complete catalytic cycle for supramolecular methanol-to-olefins conversion by linking theory with experiment. Angew. Chem. Int. Ed. 47, 5179–5182 (2008).Arstad, B., Kolboe, S. & Swang, O. Theoretical study of the heptamethylbenzenium ion. intramolecular isomerizations and C2, C3, C4 alkene elimination. J. Phys. Chem. A 109, 8914–8922 (2005).De Wispelaere, K., Hemelsoet, K., Waroquier, M. & Van Speybroeck, V. Complete low-barrier side-chain route for olefin formation during methanol conversion in H-SAPO-34. J. Catal. 305, 76–80 (2013).Wang, C. M., Wang, Y. D. & Xie, Z. K. Verification of the dual cycle mechanism for methanol-to-olefin conversion in HSAPO-34: a methylbenzene-based cycle from DFT calculations. Catal. Sci. Technol. 4, 2631–2638 (2014).Wang, C. M., Wang, Y. D., Liu, H. X., Xie, Z. K. & Liu, Z. P. Theoretical insight into the minor role of paring mechanism in the methanol-to-olefins conversion within HSAPO-34 catalyst. Micro. Mesopor. Mater. 158, 264–271 (2012).Ilias, S. & Bhan, A. The mechanism of aromatic dealkylation in methanol-to-hydrocarbons conversion on H-ZSM-5: What are the aromatic precursors to light olefins? J. Catal. 311, 6–16 (2014).Erichsen, M. W. et al. Conclusive evidence for two unimolecular pathways to zeolite-catalyzed de-alkylation of the heptamethylbenzenium cation. ChemCatChem 7, 4143–4147 (2015).Bhawe, Y. et al. Effect of cage size on the selective conversion of methanol to light olefins. ACS Catal. 2, 2490–2495 (2012).Kang, J. H. et al. Further studies on how the nature of zeolite cavities that are bounded by small pores influences the conversion of methanol to light olefins. ChemPhysChem 19, 412–419 (2018).Martin, N. et al. Nanocrystalline SSZ-39 zeolite as an efficient catalyst for the methanol-to-olefin (MTO) process. Chem. Commun. 52, 6072–6075 (2016).Dusselier, M., Deimund, M. A., Schmidt, J. E. & Davis, M. E. Methanol-to-olefins catalysis with hydrothermally treated zeolite SSZ-39. 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    Routine health management information system data in Ethiopia: consistency, trends, and challenges.

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    Background: Ethiopia is investing in the routine Health Management Information System. Improved routine data are needed for decision-making in the health sector. Objective: To analyse the quality of the routine Health Management Information System data and triangulate with other sources, such as the Demographic and Health Surveys. Methods: We analysed national Health Management Information System data on 19 indicators of maternal health, neonatal survival, immunization, child nutrition, malaria, and tuberculosis over the 2012-2018 time period. The analyses were conducted by 38 analysts from the Ministry of Health, Ethiopia, and two government agencies who participated in the Operational Research and Coaching for Analysts (ORCA) project between June 2018 and June 2020. Using a World Health Organization Data Quality Review toolkit, we assessed indicator definitions, completeness, internal consistency over time and between related indicators, and external consistency compared with other data sources. Results: Several services reported coverage of above 100%. For many indicators, denominators were based on poor-quality population data estimates. Data on individual vaccinations had relatively good internal consistency. In contrast, there was low external consistency for data on fully vaccinated children, with the routine Health Management Information System showing 89% coverage but the Demographic and Health Survey estimate at 39%. Maternal health indicators displayed increasing coverage over time. Indicators on child nutrition, malaria, and tuberculosis were less consistent. Data on neonatal mortality were incomplete and operationalised as mortality on day 0-6. Our comparisons with survey and population projections indicated that one in eight early neonatal deaths were reported in the routine Health Management Information System. Data quality varied between regions. Conclusions: The quality of routine data gathered in the health system needs further attention. We suggest regular triangulation with data from other sources. We recommend addressing the denominator issues, reducing the complexity of indicators, and aligning indicators to international definitions

    Burden of mental disorders and unmet needs among street homeless people in Addis Ababa, Ethiopia

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    BACKGROUND: The impact of mental disorders among homeless people is likely to be substantial in low income countries because of underdeveloped social welfare and health systems. As a first step towards advocacy and provision of care, we conducted a study to determine the burden of psychotic disorders and associated unmet needs, as well as the prevalence of mental distress, suicidality, and alcohol use disorder among homeless people in Addis Ababa, the capital of Ethiopia. METHODS: A cross-sectional survey was conducted among street homeless adults. Trained community nurses screened for potential psychosis and administered standardized measures of mental distress, alcohol use disorder and suicidality. Psychiatric nurses then carried out confirmatory diagnostic interviews of psychosis and administered a locally adapted version of the Camberwell Assessment of Needs Short Appraisal Schedule. RESULTS: We assessed 217 street homeless adults, about 90% of whom had experienced some form of mental or alcohol use disorder: 41.0% had psychosis, 60.0% had hazardous or dependent alcohol use, and 14.8% reported attempting suicide in the previous month. Homeless people with psychosis had extensive unmet needs with 80% to 100% reporting unmet needs across 26 domains. Nearly 30% had physical disability (visual and sensory impairment and impaired mobility). Only 10.0% of those with psychosis had ever received treatment for their illness. Most had lived on the streets for over 2 years, and alcohol use disorder was positively associated with chronicity of homelessness. CONCLUSION: Psychoses and other mental and behavioural disorders affect most people who are street homeless in Addis Ababa. Any programme to improve the condition of homeless people should include treatment for mental and alcohol use disorders. The findings have significant implications for advocacy and intervention programmes, particularly in similar low income settings. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12916-014-0138-x) contains supplementary material, which is available to authorized users

    The impact of electronic banking on customer satisfaction: A case of commercial bank of Ethiopia Hossana town branches

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    Objective of the research is how to measure the service quality in electronic  banking to improve the customer’s satisfaction and to examine the different dimensions of service quality to relate them with expectation of customers The Importance of the subject of electronic banking service and the importance of focusing on the service provided by the banks adopted, this study use seven dimensions that are very important to provide this service and they are: reliability, ease to use , privacy and security , accessibility, efficiency, responsiveness and cycle time , where the aim of this study is to measure the impact electronic banking on customer satisfaction. The study sample consisted of 381 customers from who use electronic banking: through simple regression, the results indicated that there is an effect of electronic banking services to reach customer e-satisfaction. The results showed that there is a statically significant impact of the overall service quality dimensions on electronic banking customer satisfaction. In this research the gap between perception and expectation of e-banking is analyzed by using paired t-test and it shows statically significant gap between perception and expectation of e-banking. Recommendations were given based on analysis

    Methane to Methanol Conversion on Cu-SSZ-13, -SSZ-16 and -SSZ-39

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    Direct and selective conversion of methane to methanol is a challenging reaction due to the inherent stability of methane [1]. It is known that methane can be converted to methanol on Cu-ZSM-5 and Cu- mordenite zeolites in a batch process [2-4], but the highest reported yield is only 13µmol methanol/gzeolite [5]. The reactive copper species on Cu-ZSM-5 was found to be a mono-μ-oxo-dicopper complex ([Cu–O–Cu]2+) based on an absorption feature at 22,700 cm-1 in UV–vis spectra [3,5] and several unique features in resonanceenhanced Raman spectra [6]. This species is reported to form in O2 at high temperatures (380- 450°C) [3]. We investigated conversion of methane to methanol on copper (II)-exchanged small-pore (8- membered ring) zeolites; Cu-SSZ-13 (CHA), Cu-SSZ-16 (AFX) and Cu-SSZ-39 (AEI). All the samples were active for the formation of methanol. The materials were characterized with UV– vis and Raman spectroscopy after O2 treatment to understand the structure of the reactive copper species

    Large Zeolite H-ZSM-5 Crystals as Models for the Methanol-to-Hydrocarbons Process: Bridging the Gap between Single-Particle Examination and Bulk Catalyst Analysis

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    The catalytic, deactivation, and regeneration characteristics of large coffin-shaped H-ZSM-5 crystals were investigated during the methanolto- hydrocarbons (MTH) reaction at 350 and 500 8C. Online gas-phase effluent analysis and examination of retained material thereof were used to explore the bulk properties of large coffin-shaped zeolite H-ZSM-5 crystals in a fixed-bed reactor to introduce them as model catalysts for the MTH reaction. These findings were related to observations made at the individual particle level by using polarization-dependent UV-visible microspectroscopy and mass spectrometric techniques after reaction in an in situ microspectroscopy reaction cell. Excellent agreement between the spectroscopic mea- ACHTUNGTRENUNGsurements and the analysis of hydrocarbon deposits by means of retained hydrocarbon analysis and time-of-flight secondary-ion mass spectrometry of spent catalyst materials was observed. The obtained data reveal a shift towards more condensed coke deposits on the outer zeolite surface at higher reaction temperatures. Zeolites in the fixed-bed reactor setup underwent more coke deposition than those reacted in the in situ microspectroscopy reaction cell. Regeneration studies of the large zeolite crystals were performed by oxidation in O2/inert gas mixtures at 550 8C. UV-visible microspectroscopic measurements using the oligomerization of styrene derivatives as probe reaction indicated that the fraction of strong acid sites decreased during regeneration. This change was accompanied by a slight decrease in the initial conversion obtained after regeneration. H-ZSM-5 deactivated more rapidly at higher reaction temperature
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