313 research outputs found
Rapid Static Sensitizer Regeneration Enabled by Ion Pairing
No full textAn anionic CoII complex, [Co(TTT) (NCS)3]− (TTT = 4,4′,4′′-tri-tert-butyl-2,2′:6′,2′′-terpyridine and NCS = isothiocyanate), was synthesized for use in dye-sensitized solar cells (DSSCs). The CoII complex was found to ion-pair with the hexacationic sensitizer [Ru(tmam)2(dcb)]6+ (tmam = 4,4′-bis(trimethylaminomethyl)-2,2′-bipyridine and dcb = 4,4′-(CO2H)2-2,2′-bipyridine) anchored to TiO2 thin films immersed in acetonitrile solution. Visible light excitation of the ion pairs resulted in excited-state injection followed by rapid static regeneration of the oxidized sensitizer (<10 ns). The static component to regeneration gave an ion-pair equilibrium constant of 6000 M–1. This value is an order of magnitude smaller than the equilibrium constant determined for [Ru(tmam)2(deeb)]6+ (deeb = 4,4′-(CO2Et)2-2,2′-bipyridine) dissolved in acetonitrile. DSSC studies employing [Co(TTT) (NCS)3]− or the cationic [Co(DTB)3]2+ (DTB = 4,4′-di-tert-butyl-2,2′-bipyridine) as redox mediators revealed a 3 fold photocurrent increase in the presence of the anionic cobalt complex. As the regeneration step was greatly enhanced through the formation of Coulombic ion pairs, both electron injection and regeneration were complete within 10 ns which is unprecedented for dye-sensitization. The results obtained reveal that ground-state ion-pairing can be a powerful strategy for DSSC optimization
Participatory methodologies: double-edged swords
No full textThe author puts forward the personal view that participatory methodologies (such as Participatory Rural Appraisal (PRA) and Rapid Rural Appraisal (RRA)) are often used by NGOs in such a way that they create a negative impact on the community they were intended to empower. Arguing that these methodologies incite the poor to feel the need to seem poor - a potentially disastrous starting point for any collaborative community/NGO initiative - the author advocates an approach by which communities identify their resources, and their capacity to improve their quality of life. An earlier version of this article was presented by the author at a PAMFORK Participatory Methodologies Workshop held on 24-27 September 1996 at Resurrection Gardens, Karen-Nairobi, and was published in Baobab, Issue 22 (1997).This article is hosted by our co-publisher Taylor & Francis.</p
Really unique? On the swords in the West Balt Circle
No full textThe paper deals with the problem of swords in the West Balt circle. It has been stated that they lack here almost entirely,
with the exception for several swords known. The author opposes such idea, showing new materials proving the usage
of swords in the Balt cultural milieu, specifically swords from bog sacrificial sites (Wólka, Czaszkowo) and elements of
swords’ scabbards, fittings of baldric belts aimed to hang the scabbard, or sword’s handle fitting discovered in graves
without swords themselves. That phenomenon is observed both in the Roman (the Bogaczewo culture and Dollkeim-
Kovrovo culture) and Migration Period (the Olsztyn group). It seems to prove that Balts frequently avoided placement
of swords in graves what could be expressed by the value of swords (see long usage of broken and then sharpened
swords) or ritual matters/beliefs (e.g. pars-pro-toto principle or taboo).Bartosz Kontn
Stained Swords: A Psalm of Redemption
No full textThe author proposes a novel ideal for understanding the stained swords of the Anti-Nephi-Lehies that involves repetition, parallelism, and metaphoric Hebrew wordplay
1869, Cornell University Press Podcast, Ep. 118 with Jayita Sarkar, author of Ploughshares and Swords
No full textThis episode, we speak with Jayita Sarkar, author of the new paperback and open access ebook Ploughshares and Swords: India’s Nuclear Program in the Global Cold War. Jay Sarkar is Senior Lecturer in Economic and Social History at the University of Glasgow and the Founding Director of the Global Decolonization Initiative.
We spoke to Jay about how the history of India’s first nuclear weapons test in 1974 has been overshadowed by their 1998 nuclear tests, why the conventional wisdom that India started off its nuclear program with nuclear energy first is in fact incorrect, and the strong connections between India’s nuclear program and their space program
Viking Age Swords on Gotland : A metallurgical perspective
No full textResearch about viking age swords is nothing new but for a long time the main focus have been different aspects of typologies which have evolved since early 20th century. During the last 30 years the still growing communities of Viking reenactment have shed new light upon the fighting skills of pre Christian Nordic societies. With developing knowledge of ancient metallurgy and understanding of swordsmithing we might have new ways to interpret the swords found originating in the 8th to 11th centuries. In this paper the author will be making an attempt to assess and analyze swords on Gotland to uncover whether they were made as practical fighting weapons or merely symbols of social status and power, or both.The main source of information regarding the swords found on Gotland comes from the extensive catalogues Die Wikingerzeit Gotlands I-II by Lena Thunmark-Nylén 1996, 1998 and Viking Swords by Fedir Androshchuk 2014. For a deeper understanding of the materials used in sword- and weaponsmithing, information from metalurgically examined specimens presented by Lena Thålin Bergman will be used as cross reference
Dutch Bent Iron Swords: The Microstructure of Early Iron Age Hallstatt C Bent Swords from the Netherlands
No full textDeliberately mutilated weapons and other objects are repeatedly discovered in ancient burials from the Iron Age. This research is focused on the Early Iron Age bent swords from the Hallstatt C period (800-600 BC) found in archaeological sites in the Netherlands. Metallographic research methods are used to investigate how these swords were bent, i.e., using a blacksmith’s fire or brute force. This elaborates on the Early Iron Age culture as it infers what kind of knowledge and skills were required for the bending process. With the help of a blacksmith, we created a replica to analyse the effect of different types of bending on the microstructure. This is compared with museum samples. Using optical microscopy and SEM(-EBSD) the microstructure of the museum sample and the replica are analysed for signs of deformation. Elemental analysis (SEM-EDS) is used on slag inclusion to estimate the initial iron and sword production processes. EPMA analysis was used to determine the carbon concentration throughout the samples, suggesting the use of wrought iron and hardening techniques. Results show that the Heythuysen sword contains multiple microstructure phases with various carbon concentrations. Most probably a combination of piling techniques and carburisation was applied during the production of the Heythuysen sword. The several bending methods of the replica show a distinction in the microstructure on the level of local misorientation. This is sensitive to the presence of inclusions and the changes in phase and grain size, which complicated the evaluation of the Heythuysen sword. The Heythuysen sword does not show strong evidence of bending by brute force and is most likely bent by a blacksmith with a fire.Materials Science and Engineerin
Supplementary Data for Reconstructing Past Craft Networks: A case study using 3D scans of Late Bronze Age swords to reconstruct specialized craft networks, PhD. Dissertation
No full textThis dataset includes .csv files of the network matrices, blade profile .bmp images, Fourier transform data, and the data gathered for statistics. Also included is the annotated SAS routine used to analyze the data. The Data were analyzed using SHAPE V1.3, SAS 9.4, and GEPHI 0.8.2. The data is being released with the publication of the dissertation.The data included here are supplemental data associated with the dissertation "Reconstructing Past Craft Networks: A case study using 3D scans of Late Bronze Age swords to reconstruct specialized craft networks." by Kristina Golubiewski-Davis. The dissertation is an examination of Late Bronze Age sword smiths wherein the author uses shape data as an indication of manufacture choices to reconstruct possible social networks. Included are .csv files of the Network matrices, blade profile .bmp images, Fourier transform data, and the data gathered for statistics. Also included is the annotated SAS routine used to analyze the data. The Data were analyzed using SHAPE V1.3, SAS 9.4, and GEPHI 0.8.2. The data is being released with the publication of the dissertation.Wenner-Gren Dissertation Fieldwork GrantHella Mears Summer FellowshipSummer Research Grant in Austrian/Central European Studies, University of Minnesota Center for Austrian StudiesGolubiewski-Davis, Kristina M. (2016). Supplementary Data for Reconstructing Past Craft Networks: A case study using 3D scans of Late Bronze Age swords to reconstruct specialized craft networks, PhD. Dissertation. Retrieved from the University Digital Conservancy, http://dx.doi.org/10.13020/D6PK5C
Two medieval swords from the regional museum in Jagodina
No full textThe author analyzes two medieval swords (one found near Kalenić monastery and
one near the Ćuprija town) from the funds of the Department of Archaeology
in the Regional Museum in Jagodina. He presents arguments in opposition to
the typological classification existent in scholarly literature of the first
one, and concludes that the both specimens most probably originate from the
same workshop, as were being stamped with identical maker-marks. In the end
the author draws one’s attention to circumstances of the site find of the
first sword, and also points towards possible directions of research of the
sacred topography of the Kalenić monastery environs
Governance and economic growth
No full textBecause protection of property rights cannot be appropriated by any individual, it is widely recognized as being the state's responsibility. Moreover, recent empirical evidence suggests that protection of property rights leads to higher investment levels and faster growth. The extent of property rights protection differs significantly across countries. The author integrates the emergence of property rights within a simple growth framework. Drawing on North (1990), he presents a model where economic performance and enforcement of property rights may reinforce each other.Initial conditions determine the economy's convergence to a high-income or a low-income steady state. Existing empirical evidence offers tentative support for this theory.Judicial System Reform,Labor Policies,Economic Theory&Research,Environmental Economics&Policies,Common Property Resource Development,Economic Theory&Research,Inequality,Common Property Resource Development,Environmental Economics&Policies,Governance Indicators
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