bluuebunny/crossref_metadata_2025 huggingface dataset:
DICKENS'S “JEWISH QUESTION”: PARIAH CAPITALISM AND THE WAY OUT
Authors: Nord Deborah Epstein
Published: December 2010

The story – we might almost saylegend – of how Dickens came to make the character of Riah inOur Mutual Frienda benign figure and a deliberate revision of Fagin, underworld denizen ofOliver Twist, is well known. In 1860, an Anglo-Jewish couple, J. P. and Eliza Davis, bought Charles Dickens's London home, Tavistock House. Dickens remarked to his personal secretary, William Wills, that he could not recall any “money-making dealings . . . that have been so satisfactory, considerate, and trusting” (Johnson 487). This expression of relief and slight surprise that the sale of his property to a Jewish family was without complication followed on Dickens's suspicion, crudely expressed earlier in the negotiations, that the “Jew Money-Lender” (as he referred to J. P. Davis) would not come through on the deal (Stone 243). But, though the Davises proved surprisingly cooperative in this phase of the transaction as far as Dickens was concerned, Mrs. Davis did ultimately have a complaint to register with the great writer and delivered it politely in a letter three years later. It was not about the house or the terms of purchase but rather about the character of Fagin, created by Dickens in 1837, some twenty-six years earlier. English Jews, she told him, had taken offense at this portrayal of one of their people and believed Dickens had done them a “great wrong” by offering the greedy, thieving, child-corrupting, sausage-eating criminal as representative of their “scattered nation” (Lane 98). Still, she added, while the author lived he might conceivably “justify himself or atone” for this deed. Apparently contrite and unaware of feeling any of the prejudices his portrait of the London fence might convey, Dickens declared in a letter back to Mrs. Davis that he had only “friendly feelings” for the Jews. His contrition did not end there. For the novel he was then beginning to write, Dickens would create a beneficent Jewish character, Riah, friend to the river dredger's daughter, Lizzie Hexam, and her misshapen companion, the dolls’ dressmaker, Jenny Wren. As the late-nineteenth century Anglo-Jewish poet and novelist Amy Levy put it, Dickens “trie[d] to compensate for his having affixed the label ‘Jew’ to one of his bad fairies by creating the good fairy Riah” (Levy 176).
PATER'S MOUTH
Authors: Kaiser Matthew
Published: December 2010

At New College, Oxford, Lionel Johnsonhad a reputation for sleeping past noon. On Monday, April 15, 1889, the sun was high overhead when he boasted in a letter to his friend Campbell Dodgson of his intimacy with the elusive Walter Pater, at whose London house he had spent the weekend: “I lunched with Pater, dined with Pater, smoked with Pater, went to Mass with Pater and fell in love with Pater” (Roseliep 148). That all of these friendly activities – lunching, dining, smoking, taking Communion, and perhaps even falling in love – entail opening one's mouth, or at least loosening one's lips, suggests a connection, in Johnson's eyes, between Pater's well-documented powers to charm his audience and the oral susceptibility of that audience. Getting to know thetruePater, Johnson implies, is an oral affair. His conversations with Pater, their meals, his very sense of Pater, linger on his lips. Teachers open our eyes. But Pater opens Johnson's mouth. One is tempted to dismiss the letter to Dodgson, who, like Johnson, was same-sex oriented, as youthful homoerotic banter: a campy projection of Johnson's own ambivalent and mercurial appetites. A year later, after all, in a letter to his friend Arthur Galton, Johnson recounts a “mid-day” visit he received at Oxford – whilst “lying half asleep in bed” – from Oscar Wilde, who “laughed at Pater” and “consumed all my cigarettes” (Holland and Hart-Davis 423). “I am in love with him,” Johnson declares.
WRITING AS FEMALE NATIONAL AND IMPERIAL RESPONSIBILITY: FLORENCE NIGHTINGALE'S SCHEME FOR SOCIAL AND CULTURAL REFORMS IN ENGLAND AND INDIA
Authors: Ichikawa Chieko
Published: December 2010

Florence Nightingale, who becamea national heroine after the Crimean War, was the most popular subject in hagiographical collective biographies of women during the mid- and late-1850s. However, her life can be regarded as a resolute resistance to conformity with the ideal of womanhood in the Victorian era. She recognised the chasm between her popularity and reality:

Good public! It knew nothing of what I was really doing in the Crimea.

Good public! It has known nothing of what I wanted to do & have done since I came home. (Private note from 1857; Nightingale,Ever Yours177–78)

This statement implies the resistance to the misrepresentation of her, which is indicative of her inner struggle to search for a means to express her vision.
BODIES OF SCHOLARSHIP: WITNESSING THE LIBRARY IN LATE-VICTORIAN FICTION
Authors: Cook Daniel
Published: December 2010

In one of the fictive dialoguesfrom his 1872 bookThe Poet at the Breakfast-Table, Oliver Wendell Holmes Sr. dispensed advice to any scholar planning to start a private library:

I have a kind of notion of the way in which a library ought to be put together – no, I don't mean that, I mean ought to grow. . . . A scholar must shape his own shell,secreteit one might almost say, for secretion is only separation, you know, of certain elements derived from the material world about us. And a scholar's study, with books lining its walls, is his shell. It isn't a mollusk's shell, either; it's a caddice-worm's shell. (211)

Here, the scholar's library entails separation in several senses both physical and ideal. On the one hand, books form a literal carapace insulating the scholar from the outside world – and perhaps even from the distractions of home life. At the same time, the library operates by separation in the sense of discrimination. In accumulating his library, the scholar winnows a vast textual tradition into the manageable dimensions of a single room, and curriculum just enough for a singular human life. Most interesting, however, is the suggestion that the scholar “secretes” the library, as though the books are somehow synthesized from within as an expression of, and memorial to, the scholar's essential self. The caddice worm, as Holmes informs us, “has his special fancy as to what he will pick up and glue together, with a kind of natural cement he provides himself” (211). This may strike us as a crudely glandular way of envisioning the relationship between tradition and the individual talent. Nevertheless, the passage is in keeping with the late-Victorian obsession with the private library, as well as with period representations of the scholar, who is best encountered within a concealing womb of books, carrying on secret exchange with the dusty relics of his own intellectual pilgrimage.
THE DEAD STILL AMONG US: VICTORIAN SECULAR RELICS, HAIR JEWELRY, AND DEATH CULTURE
Authors: Lutz Deborah
Published: December 2010

By the time the nineteenth centuryreached its close, it was already possible to look back at Victorian death culture with nostalgia. With the rise of secularism, the slide toward what Diana Fuss has called the death of death had begun. No longer was it common practice to hold onto the remains of the dead. Rarely would a lock of hair be kept by, to be worn as jewelry, nor did one dwell on the deathbed scene, linger upon the lips of the dying to mark and revere those last words, record the minutiae of slipping away in memorials, diaries, and letters. Rooms of houses were increasingly less likely to hold remains; no one had died in the beds in which the living slept. Walter Benjamin, who wrote often about what was lost in the nineteenth century, sees the turning away from death as going hand in hand with the disappearance of the art of storytelling. Writing in the early 1930s, he called his contemporaries “dry dwellers of eternity” because “today people live in rooms that have never been touched by death” (Illuminations94). Avoiding the sight of the dying, Benjamin argues, one misses the moment when life becomes narrative, when the meaning of life is completed and illuminated in its ending. He privileges the shared moment of death, when relatives, and even the public, gather around the dying to glean final words of wisdom, to know perhaps, in the end, the whole story. Historian of death Philippe Ariès describes a Christian account of the final ordeal of the death bed, when in the moment of death the salvation or damnation of the dying is determined, thus changing or freezing, for good, the meaning of the whole life. Scholars of nineteenth- and twentieth-century death culture tend, on the whole, to agree that towards the end of the century, a process that began earlier reached a completion – that the death of the other not only became less of a shared experience among a community, but last things such as final words and remains were increasingly to be pushed to the back of consciousness and hence to the lumber room of meaning and importance.
GEORGE EGERTON'SKEYNOTES: NIETZSCHEAN FEMINISM ANDFIN-DE-SIÈCLEFETISHISM
Authors: Brown Daniel
Published: December 2010

The title of George Egerton'sfirst collection of short stories,Keynotes(1893), announces a concern with the beginnings of sequences, the first principles from which larger patterns are orchestrated. The stories introduce premises from which new social and sexual relations may be engendered and individual existential choices made, a philosophical intent that harks back to the preoccupation in classical Greek thought with the nature of the Good Life and how to live it, which Friedrich Nietzsche renews for modern Western philosophy. Egerton's broad but nonetheless radical engagement with Nietzschean thought can be traced through the references she makes to the philosopher inKeynotes, which are widely credited with being the first in English literature. Indeed, such allusions are, as Iveta Jusová observes, “the most frequent literary reference[s] in Egerton's texts” (53). They were also recognised and mobilised against her by some of her earliest critics.
A LIFE IN FRAGMENTS: THOMAS COOPER'S CHARTISTBILDUNGSROMAN
Authors: Vargo Gregory
Published: December 2010

The improbable course of Thomas Cooper'slife (1805–1892) – from shoemaker and autodidact, to school teacher, to Methodist circuit rider, to Chartist activist, to prison poet, and finally to working-class lecturer and editor – encapsulates the tensions and contradictions of Victorian self-help. Fiercely devoted to projects of self-education and improvement, as an apprentice craftsman in Lincolnshire, Cooper memorizedHamletand significant portions ofParadise Lost, and taught himself Latin, French, and some Hebrew. The publication ofThe Purgatory of the Suicides, the epic poem for which he is best known, made Cooper a minor celebrity in the world of middle-class literary reformers, who praised his artistic and educational accomplishments. The novelist and Christian socialist Charles Kingsley discerned in his heroic commitment to “the pursuit of knowledge under difficulties” an alternative to political militancy and loosely basedAlton Locke, the story of a disillusioned Chartist hero's spiritual redemption, on Cooper's own life (Collins 3–4). Samuel Smiles, the Scottish reformer and author ofSelf-Help, celebrated Cooper's writing as part of a national culture which could help heal the country's social and economic divisions, arguing that his literary achievements placed him in “the same class as Burns, Ebenezer Elliot, Fox, the Norwich weaver-boy, to say nothing of the Arkwrights, Smeatons, Brindleys, Chantrys, and the like, all rising out of the labour-class into the class of the thinkers and builders-up of English greatness” (Smiles 244).
“LIKE BOTTLED WASPS”: BEERBOHM, HUYSMANS, AND THE DECADENTS’ SUBURBAN RETREAT
Authors: Curtin Mary Elizabeth
Published: December 2010

Such was George Orwell'svision of suburban life in his 1939 novelComing Up for Air– a vision of mindless, middle-class consumerism teetering always on the edge of financial ruin – a domestic life-in-death. Over the course of the twentieth century, suburbia has become the topos of bourgeois complacency, the locus of psychic decline. Strange, then, to think that at the end of the nineteenth century, two of Europe's Decadent writers – Max Beerbohm and Joris-Karl Huysmans – could find in the suburbs of London and Paris an aesthetic retreat from the snares of bourgeois urban life. In 1884, Huysmans publishedAgainst Nature, the paragon offin-de-siècleDecadent fiction which recounts the movement of the syphilitic aristocrat, Duc Jean Floressas des Esseintes, from the centre of Paris to the suburban village of Fontenay-aux-Roses where he constructs his anti-bourgeois aesthetic hermitage. Over ten years later, in 1896, Beerbohm published his satirical essay “Diminuendo,” in which the twenty-four-year-old writer announces his retirement from the literary world and his subsequent retreat to a quiet life of aesthetic contemplation in a London suburb. Needless to say, these suburban havens are a far cry from Orwell's sordid account of pre-war suburbia's obsession with false teeth and life insurance. Though only a little over fifty years separateAgainst Nature and Coming Up for Air, the suburbs of Huysmans and Orwell seem worlds apart. No one could imagine Des Esseintes's leather-bound study in the “Hesperides Estates,” and it seems unthinkable to picture Beerbohm locking himself away in a library amidst the cacophony of squealing infants and nagging housewives. The suburbs seem the least likely place in which the Decadent or dandy might thrive, and yet inAgainst Natureand “Diminuendo,” Huysmans and Beerbohm depict the suburbs as the last refuge of the man of taste. How could this be? What are thesefin-de-sièclesuburbs of London and Paris, and what do they signify in Huysmans's and Beerbohm's writing? These are the central questions I pose in this study of the Decadents’ retreat from urban life.
Meal pattern and BMI in 9–11-year-old children in Finland
Authors: Lehto Reetta , Ray Carola , Lahti-Koski Marjaana , Roos Eva
Published: December 2010

Objective

In many studies it has been shown that breakfast is associated with normal weight in children and adolescents. Other meals, family meals and a regular meal pattern have been less studied. Therefore, the aim of the present study was to examine whether a regular meal pattern, or breakfast, lunch or dinner as separate regular meals, is associated with the BMI of children.

Design

A cross-sectional study conducted within the Helsinki region during 2006. Study participants were measured and weighed by research staff. Children filled in a study questionnaire on their health behaviour, including the frequency of consuming meals. A regular meal was defined as one usually eaten on every school day. A regular meal pattern was defined as one consisting of a usual consumption of breakfast, school lunch and dinner on every school day. Covariance analysis was used as the statistical analysis method.

Setting

Capital region, Finland, 2006.

Subjects

A total of 604 schoolchildren (312 girls) aged 9–11 years.

Results

Irregular breakfast and an irregular meal pattern were associated with higher BMI. Regularity of school lunch, dinner or family dinner was not associated with BMI.

Conclusions

A regular breakfast and meal pattern was associated with lower BMI in children, although breakfast was the only single meal associated with BMI. We conclude that, although the association between breakfast and weight status in children is fairly consistent, the role of other meals is less convincing.
Online Human Health Risk Assessment & Management: An in-silico approach
Authors: Dwivedi Lavkush
Published: December 2010

Dreamed quality of life can be achieved by good health and further restored and maintained by the identification of health-related issues and their effective management. Human health risk assessment & management (HHRAM) approaches are applied for doing so. As internet is now increasingly being used by citizens as a major source of health information, the HHRAM approach was developed in the present study which could predict and manage online the health risks associated with any possible health hazard present in an Indian scenario. The approach is communicated to the entire population through the developed website www.healthrisk.co.in.The study was completed in three phases (1) Preparation of online health risk assessment questionnaire (HRAQ) containing variables of our interest related to personal history, occupational health status, environmental and socio-economical status (2) Design and development of the Database Management System (DBMS) to logically collect, retrieve and evaluate the collected data in a computerized format (3)Design and development of a website containing all the developed tools and other health related information for the online survey and HHRAM.Finally, health status inferences added with a few affordable management tips are configured as a risk report by DBMS and presented to every end user upon every assessment. MySQL, Microsoft office 2007, Hypertext Preprocessor (PHP) and Cascading Style Sheets (CSS) application software and computer languages were used for development. Data for more than 2000 individuals has been collected and evaluated so far.
Frost and flowers: Predicting the effects of climate change on spring frost damage using a large pollen count dataset
Authors: Katz Daniel
Published: December 2010

Background/Question/Methods

Climate change is resulting in warmer average temperatures in much of North America, leading to earlier flowering dates for most tree genera. However, earlier flowering dates can increase the chance of frost damage which may in turn reduce or eliminate seed and fruit production. This has important implications for both forest regeneration and the organisms which depend on these resources.Although specific examples, such as the “Easter frost” of 2007, show that frost damage can have extreme short term impacts on tree reproduction, we lack a general understanding of the frequency and importance of these events in non-agricultural contexts. Moreover, the magnitude by which climate change could increase these events is unknown.In this study we address the following questions: 1) How good of a predictor are environmental variables (such as temperature) for pollen release date and duration across multiple genera of North American trees? 2) How frequently and to what extent has frost damage affected pollen production over the last decade? 3) Based on temporal and spatial variation in environmental factors and tree pollen phenology, what can we predict for future decades?To investigate these questions we make use of a large pollen count dataset, derived from asthma related data collection efforts. This dataset consists of 55 urban sites across North America, and contains six years of data. Pollen was collected daily and identified to the genus level. We also make use of nearby municipal weather stations for detailed daily weather data.

Results/Conclusions

Certain genera, such as Acer, Alnus, Populus, and Quercus had relatively earlier pollen production times, putting them at higher risk of frost damage. Within each genus there was high variation in when the day of peak pollen counts occurred; for example Quercus peak days ranged from February 28th to June 7th. This variation was largely explained by environmental variables and site specific effects.We found many examples of days which had minimum temperatures sufficiently low to damage plant tissue but where pollen was still collected. For example, in the Quercus genus 223 out of 7417 pollen count observations fit these criteria, suggesting the importance of frost damage to this genus. Next, by comparing pollen count distributions between years, we show the extent to which frost damage has limited pollen production for multiple genera. Finally, we use hierarchical models to show how climate change may affect the impact of frost damage in the future.
Integrability study on a generalized (2+1)-dimensional variable-coefficient Gardner model with symbolic computation
Authors: Lü Xing , Tian Bo , Zhang Hai-Qiang , Xu Tao , Li He
Published: December 2010

Gardner model describes certain nonlinear elastic structures, ion-acoustic waves in plasmas, and shear flows in ocean and atmosphere. In this paper, by virtue of the computerized symbolic computation, the integrability of a generalized (2+1)-dimensional variable-coefficient Gardner model is investigated. Painlevé integrability conditions are derived among the coefficient functions, which reduce all the coefficient functions to be proportional only to γ(t), the coefficient of the cubic nonlinear term u2ux. Then, an independent transformation of the variable t transforms the reduced γ(t)-dependent equation into a constant-coefficient integrable one. Painlevé test shows that this is the only case when our original generalized (2+1)-dimensional variable-coefficient Gardner model is integrable.
Fatigue initiation and propagation behavior in bulk-metallic glasses under a bending load
Authors: Wang Gongyao , Liaw Peter K. , Jin Xiaoqing , Yokoyama Yoshihiko , Huang E-Wen , Jiang Feng , Keer Leon M. , Inoue Akihisa
Published: December 2010

Understanding how to predict the fatigue lifetimes of bulk-metallic glass (BMG) materials is crucially important for their selection as structural alloys. In our paper, the nature of likely fatigue mechanisms for BMGs is revealed. Fatigue cracks, arising from machining/polishing damage, were experimentally observed to initiate from shear bands near defects. At the crack tip, a plastic-zone creation is observed through the formation of many shear bands, and the fatigue crack is found to propagate along these shear bands. The size of the plastic zone can be characterized by fracture-mechanics quantities, and each fatigue cycle is seen to produce a fine striation instead of a single coarse one. We propose a shear-band mechanism to explain the characteristics of the observed fatigue cracking. Numerical computations, based on linear-elastic-fracture mechanics, yield reasonably good agreement with experiments. Our findings are significant to predict the fatigue lifetimes of these materials.
Temperature-pressure phase diagram and ferroelectric properties of BaTiO3 single crystal based on a modified Landau potential
Authors: Wang J. J. , Wu P. P. , Ma X. Q. , Chen L. Q.
Published: December 2010

A modified eighth-order Landau potential was proposed for the BaTiO3 single crystal by taking account into the quantum mechanical effects at low temperature. While all existing thermodynamic potentials for BaTiO3 fail to accurately describe the pressure dependence of ferroelectric transition temperatures, the temperature and hydrostatic pressure phase diagram constructed using the modified potential shows excellent agreement with experimental measurements by Ishidate, Abe, Takahashi, and Mori [Phys. Rev. Lett. 78, 2397 (1997)]. On the basis of the new proposed Landau potential, we calculated the dielectric coefficients, spontaneous polarizations, temperature-electric field phase diagram, and piezoelectric coefficients, all in good agreement well with existing experimental data.
Note: Direct sensor resistance-to-frequency conversion with generalized impedance converter
Authors: Muñoz D. Ramírez , Moreno J. Sánchez , Berga S. Casans , Antón A. E. Navarro
Published: December 2010

In this note a squared output signal is generated from an astable circuit. Its frequency has a linear dependence on the resistance value of a resistive temperature sensor. The main circuit to obtain this direct relationship is the generalized impedance converter configured as a capacitor controlled by a sensor resistance. The proposed measurement method allows a direct analog-to-digital interface of information involved in resistive sensors. The converter finds applications in portable low voltage and low power design of instrumentation electronic systems.
Long-term variability of global statistical properties of epileptic brain networks
Authors: Kuhnert Marie-Therese , Elger Christian E. , Lehnertz Klaus
Published: December 2010

We investigate the influence of various pathophysiologic and physiologic processes on global statistical properties of epileptic brain networks. We construct binary functional networks from long-term, multichannel electroencephalographic data recorded from 13 epilepsy patients, and the average shortest path length and the clustering coefficient serve as global statistical network characteristics. For time-resolved estimates of these characteristics we observe large fluctuations over time, however, with some periodic temporal structure. These fluctuations can—to a large extent—be attributed to daily rhythms while relevant aspects of the epileptic process contribute only marginally. Particularly, we could not observe clear cut changes in network states that can be regarded as predictive of an impending seizure. Our findings are of particular relevance for studies aiming at an improved understanding of the epileptic process with graph-theoretical approaches.
Note: Autonomous pulsed power generator based on transverse shock wave depolarization of ferroelectric ceramics
Authors: Shkuratov Sergey I. , Baird Jason , Talantsev Evgueni F.
Published: December 2010

Autonomous pulsed generators utilizing transverse shock wave depolarization (shock front propagates across the polarization vector P0) of Pb(Zr0.52Ti0.48)O3 poled piezoelectric ceramics were designed, constructed, and experimentally tested. It was demonstrated that generators having total volume of 50 cm3 were capable of producing the output voltage pulses with amplitude up to 43 kV with pulse duration 4 μs. A comparison of high-voltage operation of transverse and longitudinal shock wave ferroelectric generators is given.
Spin wave localization in a triangular nanomagnet
Authors: Lin C. S. , Lim H. S. , Wang C. C. , Adeyeye A. O. , Wang Z. K. , Ng S. C. , Kuok M. H.
Published: December 2010

Brillouin measurements have been carried out on a low density array of 20 nm thick Ni80Fe20 equilateral triangles with an edge length of 190 nm, under an in-plane magnetic field applied perpendicular to one edge of the triangular magnets. The dynamical matrix method is employed to identify the observed spin wave modes. Most of the observed modes can be classified into different categories based on their mode profiles, with modes in each category characterized by the same number of nodal lines along the direction of the applied field but having different spatial localization. Hybrid modes with different numbers of nodal lines in different regions of the nanomagnet are also found to exist. The spatial localization and the spatial variation in the spin wave character for the observed modes have been calculated based on the spin wave well model. Calculations based on the simple model give reasonable agreement with numerical results obtained by the dynamical matrix method.
High-speed microjet particles measurement using in-line pulsed holography
Authors: Li Zuoyou , Luo Zhenxiong , Liu Zhenqing , Ye Yan , Li Zeren , Zhong Jie , Li Jun
Published: December 2010

Transient in-line holographic imaging system is optimized for recording the holograms of detonation loaded microjet particles with a velocity higher than 5 km/s. Then an adaptive multithreshold image segmentation method is developed to improve the measurement precision of particle size and number. The measured size of ejected particles is from several microns to over ten microns, and the processing errors of particle number and size are less than 5% and 15%, respectively. The statistical results also show that the size, number, and velocity of microjet particles vary depending on the surface conditions of the Al metal debris. Compared with a uniform metal sample, the nonuniform metal sample with cone-shaped hole exhibits more ejected particles, larger particle size, and higher velocity.
Structural phase transitions of Na(DxH1–x)3(SeO3)2 single crystals studied by observation of H2 and N23a nuclear magnetic resonance
Authors: Lim Ae Ran , Jeong Se-Young , Kim Sun Ha
Published: December 2010

Na ( D x H 1 – x ) 3 ( SeO 3 ) 2 single crystals were grown with a deuterium content of 37%, and the spectra and relaxation times of the H2 and N23a nuclei in the mixed Na(D0.37H0.63)3(SeO3)2 crystals were measured as functions of temperature. The H2 and N23a nuclear magnetic resonance (NMR) spectra undergo changes near 213 K. Our N23a NMR results for x≥0.3 show that there is no triclinic intermediate phase; the paraelectric α-phase and ferroelectric γ-phase arise in mixed Na(D0.37H0.63)3(SeO3)2 crystals. In addition, the H2 and N23a relaxation times of mixed Na(D0.37H0.63)3(SeO3)2 crystals are different from the H2 and N23a relaxation times of NaH3(SeO3)2 and NaD3(SeO3)2. The effects of partial deuteration of sodium trihydrogen selenite crystals include not only a shift in the phase transition temperature TC but also a change in the local symmetry.
Electronic structure, optical, and magneto-optical properties of Co2CrGa Heusler alloy films: Experimental and theoretical study
Authors: Kudryavtsev Y. V. , Uvarov N. V. , Iermolenko V. N. , Dubowik J.
Published: December 2010

The optical and magneto-optical properties of bulk L21 ordered Co2CrGa Heusler alloy (HA) have been experimentally investigated for the first time below and above the Curie temperature (T≈1.2TC) and explained in terms of the band structure. It is shown that the optical properties of Co2CrGa in paramagnetic phase look similar to those in the ferromagnetic phase. Crystallization of amorphous Co2CrGa HA films with the formation of B2-type of order causes significant increase in alloy resistivity due to formation of the energy gap at the Fermi level in the minority bands. Unlike bulk L21-type ordered Co2CrGa HA sample B2 structural order of Co2CrGa HA films exhibit negative temperature coefficient of resistivity for 80–750 K temperature range. Atomic disorder causes redshift in the interband absorption peak by about 0.6 eV (and hence corresponding reduction in the energy distance between initial and final energy bands responsible for this peak formation).
First principles calculation of La3Ta0.5Ga5.5O14 crystal with acceptor-like intrinsic point defects
Authors: Chung Chan-Yeup , Yaokawa Ritsuko , Mizuseki Hiroshi , Uda Satoshi , Kawazoe Yoshiyuki
Published: December 2010

Langatate (La3Ta0.5Ga5.5O14, LTG) single crystal has been one of the promising candidate piezoelectric materials in high temperature applications because of its structural stability at high temperature. However, it has been reported that compositions of LTG grown by the Czochralski method deviates from the ideal stoichiometry to Ta-poor and Ga-rich material. In this work, to elucidate the energetic stability of defects and their influences on electronic properties, defect formation energies, and electronic properties were calculated for perfect and defective LTG crystals by using first-principles calculations. The results with oxygen-rich assumption showed that Ga substitution on Ta site and Ta vacancy were the most energetically stable defects among various acceptor-like defects under low and high Fermi energy region, respectively. The most stable cation vacancy VTa′′′′′ could affect the electronic and optical properties of the LTG crystal, as the band gap of a crystal with VTa′′′′′ has a smaller gap than other defects.
Structural and photoluminescence properties of doped and core-shell LaPO4:Eu3+ nanocrystals
Authors: Ghosh Pushpal , Kar Arik , Patra Amitava
Published: December 2010

Here, we have fabricated of LaPO4:Eu3+ doped and LaPO4/Eu2O3 core-shell nanocrystals using solution based methods. The morphologies, structure, formation mechanism, and photoluminescence properties of these nanocrystals are investigated in detail. The compressive and tensile lattice strains are obtained for hexagonal and monoclinic LaPO4 nanocrystals, respectively. Photoluminescence properties are found to be sensitive to the crystal phase, morphology, and core-shell structures. Judd–Ofelt parameters (Ω2) are calculated to understand the asymmetric nature of the dopant Eu3+ ion in LaPO4 nanocrystals host of various morphologies and crystal phases. It is seen that Ω2 value for nanorod (4.4×10−20 cm2) is higher than the nanoparticles (3.38×10−20 cm2). The quantum yield values increases from 28.27% to 52.4% by changing the crystal phase from hexagonal to monoclinic. The quantum yield of nanorods (58.50%) is higher than nanoparticles (28.68%).
Quantum scattering engineering of quantum well infrared photodetectors in the tunneling regime
Authors: Lhuillier Emmanuel , Rosencher Emmanuel , Ribet-Mohamed Isabelle , Nedelcu Alexandru , Doyennette Laetitia , Berger Vincent
Published: December 2010

Dark current is shown to be significantly reduced in quantum well infrared photodetectors in the tunneling regime, i.e., at very low temperature, by shifting the dopant impurity layers away from the central part of the wells. This result confirms that the interwell tunneling current is dominated by charged impurity scattering in usual structures. The experimental results are in good quantitative agreement with the proposed theory. This dark current reduction is pushing further the ultimate performances of quantum well infrared photodetectors for the detection of low infrared photon fluxes. Routes to further improvements are briefly sketched.
Thickness effect on the dielectric, ferroelectric, and piezoelectric properties of ferroelectric lead zirconate titanate thin films
Authors: Pérez de la Cruz J. , Joanni E. , Vilarinho P. M. , Kholkin A. L.
Published: December 2010

Lead zirconate titanate (PbZr0.52Ti0.48O3−PZT) thin films with different thicknesses were deposited on Pt(111)/Ti/SiO2/Si substrates by a sol-gel method. Single perovskite phase with (111)-texture was obtained in the thinnest films, whereas with the increase in thickness the films changed to a highly (100)-oriented state. An increase in the mean grain size as the film thickness increased was also observed. Dielectric, ferroelectric, and piezoelectric properties were analyzed as a function of the film thickness and explained based on film orientation, grain size, domain structure, domain wall motion, and nonswitching interface layers. Both serial and parallel capacitor models were used to analyze the influence of the nonswitching interface layer in the dielectric properties and the effect of substrate clamping in the microscopic piezoelectric response as the film thickness decreased. The scanning force microscopy technique was used to study the effect of thickness on the microscopic piezoresponse. Significant differences between the macroscopic and microscopic electrical properties of the films were observed. Those differences can be assigned to changes in the nonswitching film-electrode layer and domain structure.
Exciton diffusion length analysis of mixed donor materials in organic solar cells by doping with phosphorescent iridium complex
Authors: Yu Junsheng , Huang Jiang , Lin Hui , Jiang Yadong
Published: December 2010

In this paper, the photovoltaic characteristics of ITO/(t-bt)2Ir(acac):CuPc (mixed ratio R by weight)/C60/BCP/Ag organic solar cells (OSCs) are analyzed in detail. The intrinsic properties of a (t-bt)2Ir(acac):CuPc doped layer on device performance are discussed based on theoretical analysis of the experimental OSCs. By studying the photoluminescence densities of pure (t-bt)2Ir(acac) film and mixed films with R=0.75, 0.9, the key exciton diffusion lengths LD were calculated to be 28.3±5.0 nm, 31.7±5.0 nm, and 33.0±2.0 nm, respectively. A new method is then proposed to calculate LD for films with R<0.75. The analysis gives an exciton diffusion length of LD=17.4±2.5 nm for a mixed film with R=0.25, an improvement of 74% in comparison to a pure CuPc layer. Moreover, the exciton diffusion efficiency ηED of an OSC with R=0.25 is obviously improved with the assistance of an increased exciton diffusion length. Finally, to reveal the influence of the dopant (t-bt)2Ir(acac) on charge carrier collection H(V), device energy loss is analyzed and discussed.
Temperature dependent optical properties of Mn doped (Pb,Sr)TiO3 ferroelectric films in absorption region: Electron–phonon interaction
Authors: Yang J. , Gao Y. Q. , Wu J. , Huang Z. M. , Meng X. J. , Shen M. R. , Sun J. L. , Chu J. H.
Published: December 2010

The 2 mol % Mn doped Pb0.5Sr0.5TiO3 films were fabricated on sapphire substrates by chemical solution deposition. The complex dielectric functions and optical parameters of the films determined by transmittance spectroscopy in a broad temperature range of 80–500 K were investigated. Apparent thermally-driven band-gap energy shrinkage, line-width of interband electron transition broadening and the Urbach band tail behaviors were observed. The results can be mainly correlated with the renormalization of electronic band structure and band-gap energy due to the electron–phonon interaction, which is well established in terms of the Bose–Einstein model.
Near-room-temperature control of magnetization in field effect devices based on La0.67Sr0.33MnO3 thin films
Authors: Brivio S. , Cantoni M. , Petti D. , Bertacco R.
Published: December 2010

The control of the magnetization in ferromagnetic layers via electric fields is a hot topic in view of applications to the next generation of spintronic devices, where writing the magnetic information through current lines could be replaced by electric writing. Mixed valence manganites are good candidates for such a purpose because they present an intriguing coupling between ferromagnetism and charge ordering/doping which can be tuned by the application of an electric field. Here we present results on the near-room temperature control of the magnetization of optimally doped La0.67Sr0.33MnO3 ultrathin films in vertical field effect devices, where they act as top or bottom electrodes. In the latter case a slight decrease in the Curie temperature (∼5 K) is observed after application of 5×107 V/m, i.e., the maximum field preventing electric breakdown, compatible with the induced variation in the charge density and mixed valence within the Thomas Fermi screening length. These results indicate that electric fields achievable in vertical field effect devices, of the same entity of interfacial fields originating from differences in the work function in heterostructures, have only minor influence on the magnetic properties of optimally doped ultrathin La0.67Sr0.33MnO3 films.
Flare coupled metal parallel-plate waveguides for high resolution terahertz time-domain spectroscopy
Authors: Theuer Michael , Harsha S. Sree , Grischkowsky D.
Published: December 2010

We report on a new coupling scheme for high resolution terahertz spectroscopy of microcrystalline films using parallel-plate waveguides. Metal flares are used to couple the terahertz radiation into and out of the waveguide. Very good coupling ratios as high as 35% at 1 THz from a collimated free-space beam into a subwavelength gap are obtained. This microwave approach is compared in terms of coupling ratio and spectral characteristics to the established technique of quasioptic coupling to parallel-plate waveguides using silicon lenses. Various samples at room and cryogenic temperatures are measured to show the capabilities of flare coupling for high resolution terahertz spectroscopy.
Charge carrier extraction by linearly increasing voltage: Analytic framework and ambipolar transients
Authors: Lorrmann J. , Badada B. H. , Inganäs O. , Dyakonov V. , Deibel C.
Published: December 2010

Up to now the basic theoretical description of charge extraction by linearly increasing voltage (CELIV) is solved for a low conductivity approximation only. Here we present the full analytical solution, thus generalize the theoretical framework for this method. We compare the analytical solution and the approximated theory, showing that especially for typical organic solar cell materials the latter approach has a very limited validity. Photo-CELIV measurements on poly(3-hexyl thiophene-2,5-diyl):[6,6]-phenyl-C61 butyric acid methyl ester based solar cells were then evaluated by fitting the current transients to the analytical solution. We found that the fit results are in a very good agreement with the experimental observations, if ambipolar transport is taken into account, the origin of which we will discuss. Furthermore we present parametric equations for the mobility and the charge carrier density, which can be applied over the entire experimental range of parameters.
Cu related doublets green band emission in ZnO:Cu thin films
Authors: Liu Yuanda , Liang Hongwei , Xu Lu , Zhao Jianze , Bian Jiming , Luo Yingmin , Liu Yang , Li Wancheng , Wu Guoguang , Du Guotong
Published: December 2010

Cu-doped ZnO (ZnO:Cu) thin films were grown on Si (111) substrate by low-pressure metal-organic chemical vapor deposition equipment. The crystal structures and optical properties of as-grown sample were examined. X-ray diffraction patterns indicated a lattice relaxation after the Cu doping. The incorporation of Cu atoms into ZnO film and its existence in a bivalent state were demonstrated by x-ray photoelectron spectroscopy measurements. Low-temperature photoluminescence was carried out at temperature of 11.4 K for both unintentionally doped and Cu-doped ZnO films. A characteristic green-luminescence with fine structure consisted of doublets emission peak was observed, which was believed to be associated with Cu doping. A theoretical model based on hydrogen analog has been proposed to explain this phenomenon. It provides new information about the detailed role of Cu in ZnO thin films.
Ab initio study of lattice vibration and polaron properties in zinc-blende AlxGa1−xN alloys
Authors: Bouarissa N. , Saib S.
Published: December 2010

We report on first-principles studies to investigate the zone-centre optical phonons and polaron properties in zinc-blende AlxGa1−xN alloys over the whole compositional range. The calculations are performed using ab initio pseudopotential approach based on the density functional perturbation theory under the virtual crystal approximation. Features such as phonon frequencies, dielectric constants, Fröhlich coupling constant, Debye temperature, effective polar field, deformation potential, and polaron effective mass have been determined. Reasonable agreement is obtained between our computed values and data available in the literature. Other case, our results are predictions. The phonon modes are broadened upon alloying and their frequencies display a blueshift with increasing Al content. The dependence of the studied parameters on Al concentration is found to be monotonic.
Influence of polarization-induced electric fields on coherent electron tunneling in AlN/GaN coupled double quantum wells
Authors: Cen L. B. , Shen B. , Huang C. C. , Xu F. J. , Qin Z. X. , Zhang G. Y. , Chen X. S. , Lu W.
Published: December 2010

The influence of polarization-induced electric fields on the coherent electron tunneling probability in AlN/GaN coupled double quantum wells (CDQWs) has been performed by solving Schrödinger and Poisson equations self-consistently. It is found that when the first excited state (E2) and the second excited state (E3) resonate in AlN/GaN CDQWs, the coherent electron tunneling probability is 16 times higher than that in AlN/GaN single quantum well, which is attributed to the Fabry–Perot quantum interference mechanism in AlN/GaN CDQWs. However, the coherent electron tunneling probability decreases rapidly with the polarization-induced electric fields increasing, which is attributed to the resonance between the E2 and E3 subbands weakening with the polarization-induced electric fields increasing in AlN/GaN CDQWs.
Effect of Ag or Sb addition on the thermoelectric properties of PbTe
Authors: Dow H. S. , Oh M. W. , Kim B. S. , Park S. D. , Min B. K. , Lee H. W. , Wee D. M.
Published: December 2010

In this study, the effect of Ag or Sb addition on the thermoelectric properties of PbTe including the Seebeck coefficient, the electrical resistivity, and the thermal conductivity, was studied in the temperature range from 323 to 723 K. The major carriers in the Ag-doped and the Sb-doped PbTe are holes and electrons, respectively. A degenerate semiconductor behavior in the electrical transport properties was observed in the Ag-doped, whereas the semi-metallic in the Sb-doped. It was suggested from the results of the Hall effect measurement and the Seebeck coefficient that the effective mass was significantly altered by the Sb-doping. The maximum dimensionless figure of merit, ZT, of Pb1−xAgxTe and Pb1−xSbxTe (x=0.1) alloys showed 0.27 and 0.62 at 723 K, respectively. Based on the analysis of the Seebeck coefficient of the Ag or the Sb-doped PbTe, the interaction between Ag and Sb in PbTe, as expected in the AgPbmSbTem+2 (LAST-m), may be supposed.
Trapped hybrid modes in solidly mounted resonators based on c-axis oriented hexagonal crystals
Authors: Wathen Adam D. , Munir Farasat , Hunt William D.
Published: December 2010

Assuming an idealized piezoelectric bulk acoustic wave resonator, one typically calculates the velocity of the fundamental bulk acoustic mode as the measured frequency times twice the thickness of the piezoelectric film. In c-axis 6mm hexagonal crystals of (e.g., ZnO or AlN), both the longitudinal and thickness shear modes are peizoelectrically active using thickness excitation and lateral-field excitation, respectively. Without a loss of generality, we concentrate our study on ZnO films. The theoretical velocity of the pure thickness shear mode in sputtered ZnO, based strictly on reported material properties, is calculated to be approximately 2580 m/s. However, a variety of acoustic velocities for the thickness shear mode in ZnO have been reported in the literature ranging from about 3100–3500 m/s. These reported values represent a 20%–36% increase in acoustic velocity relative to the theoretical values. In the literature, this deviation is typically attributed to ZnO film inconsistencies and other phenomena which can be difficult to quantify. We propose that the reported inconsistencies may be attributed to a hybrid acoustic mode comprised of a coupling of shear and longitudinal particle displacements. In this paper, we present a theoretical description of a hybrid mode in ZnO solidly mounted resonator (SMR) devices. We begin first with an experimental verification of a mode with a changing velocity in a ZnO SMR with the only variable being the ZnO thickness. Using the acoustic velocity through the thickness as an effective velocity with which to reference the mode, we find the effective acoustic velocity to range from 3100–3900 m/s, with increasing ZnO thickness. We then start from the first principles of piezoelectric acoustic wave propagation and derive three coupled partial differential equations describing a hybrid mode comprised of the coupling between longitudinal and shear particle displacement and the corresponding piezoelectrically generated potential in the ZnO film. The qualitative findings described by the derived equations are then further investigated with finite element simulation (COMSOL MULTIPHYSICS®). We simulate the performance of our experimental devices using the COMSOL platform, examine the eigenfrequencies of the structure, and find a hybrid mode which is trapped both vertically and laterally in the ZnO film. Calculating the effective velocity of the simulated modes, we find the simulated effective velocities to be within 1.5% of our measured results. Finally, we compare simulation results to experimentally measured results of a previously observed hybrid mode and achieve a 0.2% agreement.
Metamagnetic transitions and magnetocaloric effect in epitaxial Ni–Co–Mn–In films
Authors: Niemann R. , Heczko O. , Schultz L. , Fähler S.
Published: December 2010

Due to their large strains and multifunctionality, magnetic shape memory alloys are of particular interest for microsystems. Here epitaxially grown metamagnetic Ni–Co–Mn–In films on MgO (001) are analyzed which exhibit a magnetically induced austenite transition. This opens the way to use Ni–Co–Mn–In films in microactuators combining high stroke with high forces. Additionally these films exhibit an inverse magnetocaloric effect with an entropy change of 8.8 J kg−1 K−1 in 9 T at 353 K. The high surface-to-volume fraction of films promises a fast heat exchange, which is beneficial for efficient magnetic cooling.