Equivalent circuit parameters of the film-covered magnesium/electrolyte interface in Mg/MnO2 dry cells from transient and ac impedance measurements

The electrochemical properties of the film-covered anode/solution interface in the magnesium/ manganese dioxide dry cell have been evaluated. The most plausible electrical equivalent circuit description of the Mg/solution interface with the passive film intact, has been identified. These results are based on the analysis of ac impedance and voltage transient measurements made on the dry cell under conditions which cause no damage to the protective passive film on the anode. The study demonstrates the complementary character of impedance and transient measurements when widely different frequency ranges are sampled in each type of investigation. The values and temperature dependence of the anode-film resistance, film capacitance, double-layer capacitance and charge-transfer resistance of the film-covered magnesium/solution interface have been determined. The magnitude of these values and its implications in understanding the important performance aspects of the magnesium/manganese dioxide dry cell are discussed. The study may be extended, in principle, to Li, Al and Ca batteries.

Antimicrobial activity of highly stable silver nano particles embedded in agar-agar matrix as a thin film

Highly stable silver nanoparticles (Ag NPs) in agar-agar (Ag/agar) as inorganic-organic hybrid were obtained as free-standing film by in situ reduction of silver nitrate by ethanol. The antimicrobial activity of Ag/agar film on Escherichia coli (E. coil), Staphylococcus aureus (S. aureus), and Candida albicans (C albicans) was evaluated in a nutrient broth and also in saline solution. In particular, films were repeatedly tested for antimicrobial activity after recycling. UV-vis absorption and TEM studies were carried out on films at different stages and morphological studies on microbes were carried out by SEM. Results showed spherical Ag NPs of size 15-25 nm, having sharp surface plasmon resonance (SPR) band. The antimicrobial activity of Ag/agar film was found to be in the order, C. albicans > E. coil > S. aureus, and antimicrobial activity against C. albicans was almost maintained even after the third cycle. Whereas, in case of E. coil and S. aureus there was a sharp decline in antimicrobial activity after the second cycle. Agglomeration of Ag NPs in Ag/agar film on exposure to microbes was observed by TEM studies. Cytotoxic experiments carried out on HeLa cells showed a threshold Ag NPs concentration of 60 mu g/mL, much higher than the minimum inhibition concentration of Ag NPs (25.8 mu g/mL) for E. coli. The mechanical strength of the film determined by nanoindentation technique showed almost retention of the strength even after repeated cycle. (C) 2010 Elsevier Ltd. All rights reserved.

Effect of process variables on die-billet temperature history in a slow speed hot coining type process

A computer code is developed as a part of an ongoing project on computer aided process modelling of forging operation, to simulate heat transfer in a die-billet system. The code developed on a stage-by-stage technique is based on an Alternating Direction Implicit scheme. The experimentally validated code is used to study the effect of process specifics such as preheat die temperature, machine ascent time, rate of deformation, and dwell time on the thermal characteristics in a batch coining operation where deformation is restricted to surface level only.

On the uniformity of film thickness on rotating spherical substrates on a planar work holder

Curves for the uniformity in film thickness on spherical substrates are drawn for various geometries. The optimum source-to-substrate height for maximum uniformity of the film thickness is determined. These data are approximated to achieve uniform thickness on a large number of small planar substrates loaded on a large spherical substrate holder, the appropriate geometry being selected on the basis of the radius of curvature of the substrate holder.

Thin film amorphous semiconductor microwave switches

Microwave switches operating in the X band were designed and fabricated using amorphous chalcogenide semiconductors of composition GexTeyAsz. Threshold devices were shown to operate as microwave modulators at modulation frequencies of up to 100 MHz. No delay time was observed at the highest frequency although the modulation efficiency decreased above 10 MHz owing to the finite recovery time which was approximately 0.3 × 10−8s. The devices can also be used as variolossers, the insertion loss being 0.5 dB in the OFF state and increasing on switching from 5 dB at 1 mA device current to 18 dB at 100 mA.The behaviour of the threshold switches can be explained in terms of the formation of a conducting filament in the ON state with a constant current density of 2 × 104Acm−2 that is shunted by the device capacitance. The OFF state conductivity σ varies as ωn (0.5 < n < 1) which is characteristic of hopping in localized states. However, there was evidence of a decrease in n or a saturation of the conductivity at high frequencies.As a result of phase separation memory switches require no holding current in the ON state and may be used as novel latching semiconductor phase-shifters.

Electrical switching behavior of amorphous Al23Te77 thin film sample

The electrical switching behavior of amorphous Al23Te77 thin film devices, deposited by flash evaporation, has been studied in co-planar geometry. It is found that these samples exhibit memory type electrical switching. Scanning Electron Microscopic studies show the formation of a crystalline filament in the electrode region which is responsible for switching of the device from high resistance OFF state to low resistance ON state. It is also found that the switching behavior of thin film Al-Te samples is similar to that of bulk samples, with the threshold fields of bulk samples being higher. This has been understood on the basis of higher thermal conductance in bulk, which reduces the Joule heating and temperature rise in the electrode region. (C) 2010 Elsevier B.V. All rights reserved.

A Shared European History? Perceptions of Imperialism and Islam in Matriculation Examination Essays and History Textbooks

The European Union (EU) is faced with a continuous decrease in public support. There is a tension between the growing Euroscepticism and the concurrent academic discourse of a shared European identity. Informed and inspired by the current debates, this Master’s Thesis investigates the potential of a shared past to create shared identity. It also addresses the logic of cultural exclusion that is often connected to collective cultural identities. The source material is a combination of exam essays, written as answers to the history tests in the Finnish matriculation examinations of 2005-2008, and upper secondary school history textbooks. From the sources, current perceptions of Islam (as Europe’s Other) and the age of imperialism (as a debated period from Europe’s past) among the youth are studied. Through the analysis the thesis aims to indicate the level of consensus within the pupils’ identification with the past and with Europe. This objective is pursued through examining the pupils’ perceptions of Europe’s past and its relationship to non-European cultures and countries as they are manifested in the essays, and reflecting upon the level of influence that history textbooks as representatives of national hegemonic historical narratives might have on the contents, framings and emphases with and through which the pupils approach, imagine, and reproduce Europe’s past. The approach is based on previous research on the presence of history and the field of textbook research. The theoretical categories with which the sources are analyzed are derived primarily from literature on identity, European integration, history and memory, postcolonial criticism, and theorizations of European identity. Results of the research project suggest that the rhetoric of European superiority, despite its apparent demise, still resonates in contemporary understandings of Europeanness. Dominant perceptions of imperialism comprise of European agency and colonial submission, dominant perceptions of the Islamic world of fundamental difference. Identification with European history among the Finnish youth is rather shallow when examined through perceptions of imperialism; the Islamic world is perceived as Other and its representations are dominated by recent and contemporary international relations.

Characterization of a large-area PVDF thin film for electro-mechanical and ultrasonic sensing applications

Large-area PVDF thin films have been prepared and characterized for quasi-static and high frequency dynamic strain sensing applications. These films are prepared using hot press method and the piezoelectric phase (beta-phase) has been achieved by thermo-mechanical treatment and poling under DC field. The fabricated films have been characterized for quasi-static strain sensing and the linear strain-voltage relationship obtained is promising. In order to evaluate the ultrasonic sensing properties, a PZT wafer has been used to launch Lamb waves in a metal beam on which the PVDF film sensor is bonded at a distance. The voltage signals obtained from the PVDF films have been compared with another PZT wafer sensor placed on the opposite surface of the beam as a reference signal. Due to higher stiffness and higher thickness of the PZT wafer sensors, certain resonance patterns significantly degrade the sensor sensitivity curves. Whereas, the present results show that the large-area PVDF sensors can be superior with the signal amplitude comparable to that of PZT sensors and with no resonance-induced effect, which is due to low mechanical impedance, smaller thickness and larger area of the PVDF film. Moreover, the developed PVDF sensors are able to capture both A(0) and S-0 modes of Lamb wave, whereas the PZT sensors captures only A(0) mode in the same scale of voltage output. This shows promises in using large-area PVDF films with various surface patterns on structures for distributed sensing and structural health monitoring under quasi-static, vibration and ultrasonic situations. (C) 2010 Elsevier B.V. All rights reserved.

The Enlightenment Idea of History as a Legitimation Tool of Kemalism in Turkey

The study analyzes the effort to build political legitimacy in the Republic of Turkey by ex-ploring a group of influential texts produced by Kemalist writers. The study explores how the Kemalist regime reproduced certain long-lasting enlightenment meta-narrative in its effort to build political legitimacy. Central in this process was a hegemonic representation of history, namely the interpretation of the Anatolian Resistance Struggle of 1919 1922 as a Turkish Revolution executing the enlightenment in the Turkish nation-state. The method employed in the study is contextualizing narratological analysis. The Kemalist texts are analyzed with a repertoire of concepts originally developed in the theory of narra-tive. By bringing these concepts together with epistemological foundations of historical sciences, the study creates a theoretical frame inside of which it is possible to highlight how initially very controversial historical representations in the end manage to construct long-lasting, emotionally and intellectually convincing bases of national identity for the secular middle classes in Turkey. The two most important explanatory concepts in this sense are di-egesis and implied reader. The diegesis refers to the ability of narrative representation to create an inherently credible story-world that works as the basis of national community. The implied reader refers to the process where a certain hegemonic narrative creates a formula of identification and a position through which any individual real-world reader of a story can step inside the narrative story-world and identify oneself as one of us of the national narra-tive. The study demonstrates that the Kemalist enlightenment meta-narrative created a group of narrative accruals which enabled generations of secular middle classes to internalize Kemalist ideology. In this sense, the narrative in question has not only worked as a tool utilized by the so-called Kemalist state-elite to justify its leadership, but has been internalized by various groups in Turkey, working as their genuine world-view. It is shown in the study that secular-ism must be seen as the core ingredient of these groups national identity. The study proposes that the enlightenment narrative reproduced in the Kemalist ideology had its origin in a simi-lar totalizing cultural narrative created in and for Europe. Currently this enlightenment project is challenged in Turkey by those who are in an attempt to give religion a greater role in Turkish society. The study argues that the enduring practice of legitimizing political power through the enlightenment meta-narrative has not only become a major factor contributing to social polarization in Turkey, but has also, in contradiction to the very real potentials for crit-ical approaches inherent in the Enlightenment tradition, crucially restricted the development of critical and rational modes of thinking in the Republic of Turkey.

Tiedostumaton nykytaiteessa : Katse, ääni ja aika vuosituhannen taitteen suomalaisessa nykytaiteessa

Leevi Haapala explores moving image works, sculptures and installations from a psychoanalytic perspective in his study The Unconscious in Contemporary Art. The Gaze, Voice and Time in Finnish Contemporary Art at the Turn of the Millennium . The artists included in the study are Eija-Liisa Ahtila, Hans-Christian Berg, Markus Copper, Liisa Lounila and Salla Tykkä. The theoretical framework includes different psychoanalytic readings of the concepts of the gaze, voice and temporality. The installations are based on spatiality and temporality, and their detailed reading emphasizes the medium-specific features of the works as well as their fragmentary nature, heterogeneity and affectivity. The study is cross-disciplinary in that it connects perspectives from the visual culture, new art history and theory to the interpretation of contemporary art. The most important concepts from psychoanalysis, affect theory and trauma discourse used in the study include affect, object a (objet petit a) as articulated by Jacques Lacan, Sigmund Freud s uncanny (das Unheimliche) and trauma. Das Unheimliche has been translated as uncanny in art history under the influence of Rosalind Krauss. The object of the study, the unconscious in contemporary art, is approached through these concepts. The study focuses on Lacan s additions to the list of partial drives: the gaze and voice as scopic and invocative drives and their interpretations in the studies of the moving image. The texts by the American film theorist and art historian Kaja Silverman are in crucial role. The study locates contemporary art as part of trauma culture, which has a tendency to define individual and historical experiences through trauma. Some of the art works point towards trauma, which may appear as a theoretic or fictitious construction. The study presents a comprehensive collection of different kinds of trauma discourse in the field of art research through the texts of Hal Foster, Cathy Caruth, Ruth Leys and Shoshana Felman. The study connects trauma theory with the theoretical analysis of the interference and discontinuity of the moving image in the readings by Susan Buck-Morss, Mary Ann Doane and Peter Osborn among others. The analysis emphasizes different ways of seeing and multisensoriality in the reception of contemporary art. With their reflections and inverse projections, the surprising mechanisms of Hans-Christian Berg s sculptures are connected with Lacan s views on the early mirroring and imitation attempts of the individual s body image. Salla Tykkä s film trilogy Cave invites one to contemplate the Lacanian theory of the gaze in relation to the experiences of being seen. The three oceanic sculpture installations by Markus Copper are studied through the vocality they create, often through an aggressive way of acting, as well as from the point of view of the functioning of an invocative drive. The study compares the work of fiction and Freud s texts on paranoia and psychosis to Eija-Liisa Ahtila s manuscripts and moving image installations about the same topic. The cinematic time in Liisa Lounila s time-slice video installations is approached through the theoretical study of the unconscious temporal structure. The viewer of the moving image is inside the work in an in-between state: in a space produced by the contents of the work and its technology. The installations of the moving image enable us to inhabit different kinds of virtual bodies or spaces, which do not correspond with our everyday experiences. Nevertheless, the works of art often try to deconstruct the identification to what has been shown on screen. This way, the viewer s attention can be fixed on his own unconscious experiences in parallel with the work s deconstructed nature as representation. The study shows that contemporary art is a central cultural practice, which allows us to discuss the unconscious in a meaningful way. The study suggests that the agency that is discursively diffuse and consists of several different praxes should be called the unconscious. The emergence of the unconscious can happen in two areas: in contemporary art through different senses and discursive elements, and in the study of contemporary art, which, being a linguistic activity is sensitive to the movements of the unconscious. One of the missions of art research is to build different kinds of articulated constructs and to open an interpretative space for the nature of art as an event.

Phylogeography and demographic history of Lacerta lepida in the Iberian Peninsula

The Iberian Peninsula is recognized as an important refugial area for species survival and diversification during the climatic cycles of the Quaternary. Recent phylogeographic studies have revealed Iberia as a complex of multiple refugia. However, most of these studies have focused either on species with narrow distributions within the region or species groups that, although widely distributed, generally have a genetic structure that relates to pre-Quaternary cladogenetic events. In this study we undertake a detailed phylogeographic analysis of the lizard species, Lacerta lepida, whose distribution encompasses the entire Iberian Peninsula. We attempt to identify refugial areas, recolonization routes, zones of secondary contact and date demographic events within this species. Results support the existence of 6 evolutionary lineages (phylogroups) with a strong association between genetic variation and geography, suggesting a history of allopatric divergence in different refugia. Diversification within phylogroups is concordant with the onset of the Pleistocene climatic oscillations. The southern regions of several phylogroups show a high incidence of ancestral alleles in contrast with high incidence of recently derived alleles in northern regions. All phylogroups show signs of recent demographic and spatial expansions. We have further identified several zones of secondary contact, with divergent mitochondrial haplotypes occurring in narrow zones of sympatry. The concordant patterns of spatial and demographic expansions detected within phylogroups, together with the high incidence of ancestral haplotypes in southern regions of several phylogroups, suggests a pattern of contraction of populations into southern refugia during adverse climatic conditions from which subsequent northern expansions occurred. This study supports the emergent pattern of multiple refugia within Iberia but adds to it by identifying a pattern of refugia coincident with the southern distribution limits of individual evolutionary lineages. These areas are important in terms of long-term species persistence and therefore important areas for conservation.

Performance study of a pressure transducer with meandering-path thin film strain gauges

The performance of a pressure transducer with meandering-path thin film strain gauges has been studied. Details of the procedure followed to prepare the thin film strain gauge system on the pressure transducer diaphragm are given. The effect of post-deposition heat treatment on the resistance of the sensing films of the strain gauges and the insulating base layers are discussed. The output of the pressure transducer was studied with various input pressures and excitation voltages. It was found that up to a maximum of 10 V bridge excitation the output was stable and repetitive. The maximum non-linearity and hysteresis observed are ±0.15%, ±0.16% and ±0.14% FSO (full-scale output) for 5, 7.5 and 10 V excitation respectively. Information on the output behaviour of the pressure transducer with temperature is also included.

A novel laser direct write technique for fabrication of thin film MICs

A technique for fabrication of thin-film circuits for microwave integrated circuit (MIC) application is presented. This low-cost fabrication technique utilizes laser direct write of copper patterns on alumina substrates. The method obviates the need for photomasks and photolithography. The film deposition mechanism, deposit film analysis, and MIC fabrication sequence are presented. Performance evaluation of MICs fabricated using this technique is also included

Diaphragm-type sputtered platinum thin film strain gauge pressure transducer

A diaphragm-type pressure transducer with a sputtered platinum film strain gauge (sensing film) has been designed and fabricated. The various steps followed to prepare thin film strain gauges on the diaphragm are described. M-bond 450 adhesive (Measurements Group, USA) has been employed as the insulating layer. A detailed procedure to cure this layer is given. A d.c. sputtering method is employed to prepare the platinum films. This paper also includes details of the strain gauge pattern and its location on the diaphragm. A description of the output characteristics and overall behaviour of the platinum thin film pressure transducer is reported.

Effect of tolerance on the propagation characteristic of a superconducting thin film microstrip delay line

The propagation constant of a superconducting microstrip transmission delay line is evaluated using the spectral domain immitance approach, modelling the superconductor as a surface current having an equivalent surface impedance found through the complex resistive boundary condition. The sensitivity approach is used to study the beta variations with substrate parameters and film characteristics. Results show that the surface impedance does not have much influence on beta sensitivities with respect to epsilon r, W and h. However, it can be observed that the surface impedance plays a crucial role in determining the optimum design.