bluuebunny/crossref_metadata_2025 huggingface dataset:
Genomics and the Ark: An Ecocentric Perspective on Human History
Authors: Zwart Hub , Penders Bart
Published: May 2011

Views of ourselves in relationship to the rest of the biosphere are changing. Theocentric and anthropocentric perspectives are giving way to more ecocentric views on the history, present, and future of humankind. Novel sciences, such as genomics, have deepened and broadened our understanding of the process of anthropogenesis, the coming into being of humans. Genomics suggests that early human history must be regarded as a complex narrative of evolving ecosystems, in which human evolution both influenced and was influenced by the evolution of companion species. During the agricultural revolution, human beings designed small-scale artificial ecosystems or evolutionary "Arks," in which networks of plants, animals, and microorganisms coevolved. Currently, our attitude towards this process seems subject to a paradoxical reversal. The boundaries of the Ark have dramatically broadened, and genomics is not only being used to increase our understanding of our ecological past, but may also help us to conserve, reconstruct, or even revivify species and ecosystems to whose degradation or (near) extinction we have contributed. This article explores the role of genomics in the elaboration of a more ecocentric view of ourselves with the help of two examples, namely the renaissance of Paleolithic diets and of Pleistocene parks. It argues that an understanding of the world in ecocentric terms requires new partnerships and mutually beneficial forms of collaboration and convergence between life sciences, social sciences, and the humanities.
A Reformulation of the Social Brain Theory for Schizophrenia: The Case for Out-Group Intolerance
Authors: Abed Riadh T. , Abbas Mohammed J.
Published: May 2011

This article proposes a reformulation of the social brain theory of schizophrenia. Contrary to those who consider schizophrenia to be an inherently human condition, we suggest that it is a relatively recent phenomenon, and that the vulnerability to it remained hidden among our hunter-gatherer ancestors. Hence, we contend that schizophrenia is the result of a mismatch between the post-Neolithic human social environment and the design of the social brain. We review the evidence from human evolutionary history of the importance of the distinction between ingroup and out-group membership that lies at the heart of intergroup conflict, violence, and xenophobia. We then review the evidence for the disparities in schizophrenia incidence around the world and for the higher risk of this condition among immigrants and city dwellers. Our hypothesis explains a range of epidemiological findings on schizophrenia related to the risk of migration and urbanization, the improved prognosis in underdeveloped countries, and variations in the prevalence of the disorder. However, although this hypothesis may identify the ultimate causation of schizophrenia, it does not specify the proximate mechanisms that lead to it. We conclude with a number of testable and refutable predictions for future research.
The Physician-Administrator as Patient: Distinctive Aspects of Medical Care
Authors: Cappell Mitchell S.
Published: May 2011

This article examines distinctive aspects of medical care experienced by a 55-year-old hospitalized for quintuple coronary artery bypass surgery who was also a senior physician-administrator (chief of gastroenterology) at the same hospital. The article describes eight distinctive aspects of administrator-physicians as patients, including special patient treatment; exalted patient expectations by hospital personnel; patient suppression of emotions; patient denial; self-doctoring; job stress contributing to disease; self-sacrifice to achieve better health; and rational medical decisions when not under stress. Health-care workers should recognize how these distinctive aspects of medical care and behavior affect administrator-physicians as patients, in order to mitigate their negative effects, potentiate their positive effects, and optimize the care of these patients.
A Consumer's Guide to Superorganisms
Authors: Ghiselin Michael T.
Published: May 2011

The organism, like the molecule, the cell, and the species, is one of the fundamental levels in our hierarchical classification of life and its components. The units ranked at these levels, being concrete, particular things, are individuals in the broadest philosophical sense. But in a much narrower and more familiar sense, individual means an individual organism. Like species , the term individual is hard to define, but in most biological discourse it has meant the unit of philosophical autonomy. Some authors have attempted to revise this terminology, restricting individual to organisms, and redefining organism to include families and other units. Such semantic surgery is unnecessary if the goal is merely to justify selection at more than one level. Analogies between levels may be interesting, but many of them do not deserve to be taken seriously.
The Différance that Makes All the Difference: A Comparison of Derrida and Śaṅkara
Authors: Olson Carl
Published: May 2011

This essay compares Śaṅkara and Jacques Derrida on the issue of difference. This hermeneutical dialogue compares the two thinkers with respect to the following items: différance and nonduality; presence and trace; being and alterity; and truth, meaning, and reality. This essay intends to compare Śaṅkara and Derrida on what the latter calls différance because it is a central notion in his postmodern philosophy, whereas nondualism is stressed by the former philosopher. Therefore, this comparison engages two philosophies that move in completely different directions.
Immortality and Significance
Authors: Smuts Aaron
Published: May 2011

Although I reject his argument, I defend Bernard Williams's claim that we would lose reason to go on if we were to live forever. Through a consideration of Borges's story "The Immortal," I argue that immortality would be motivationally devastating, since our decisions would carry little weight, our achievements would be hollow victories of mere diligence, and the prospect of eternal frustration would haunt our every effort. An immortal life for those of limited ability will inevitably result in endless frustration, since the number of significant projects that one is capable of completing is finite, but the span of time is infinite.
"Me" First or "We" First?: Literature and Paleomorality
Authors: Swirski Peter
Published: May 2011

Bernard Malamud's God's Grace (1982) is a neo-Darwinian Beast Fable about morality in a thermonuclear age. It serves me as a starting point for a fresh look at the fundamental questions surrounding morality and altruism. There is no doubt any more that, from the standpoint of multilevel selection, morality is a form of compromise among competing spheres of genetic self-interest. The result is a tug-of-war between two adaptive vectors: the egoistic and competitive "me first" versus the prosocial and cooperative "we-first."
Narrative Accidents and Literary Miracles
Authors: Horowitz Evan
Published: May 2011

When I crash my car, it may be an accident, but when Daisy Buchanan crashes hers, it is something else. The distinction has nothing to do with our varying intentions; it is simply that her accident occurs within the carefully-designed world of narrative. Working with car crashes, stray shootings, and train wrecks, I show how difficult it is to find genuine accidents in literature and how that bare fact limits the insight of historical criticism.
Understanding Another's Wrongdoing
Authors: Cowley Christopher
Published: May 2011

What does it mean to understand a murderer? Might it be legitimate to refuse to even try? And is such a refusal compatible with enduring love? I examine Sonia's reaction to Raskolnikov's confession in Dostoyevsky's Crime and Punishment . On the one hand, not only does she not abandon him, she devotes the rest of her life to him; on the other hand, she rejects not only his attempted justifications, but even the possibility of justification itself. This is a special kind of moral experience that strikes at many assumptions of analytic moral philosophy and its reliance on thought experiments.
There Goes the Neighborhood: Cycling Ethnoracial Tensions in Will Eisner’s Dropsie Avenue
Authors: Royal Derek Parker
Published: May 2011

Unlike many of Will Eisner’s graphic novels, texts concerned primarily with Jewish families and communities, Dropsie Avenue (1995) takes on the broader theme of American ethnoracial relations and the dynamics of urban assimilation. It offers a critical and even neo-naturalistic reading of the traditional “melting pot” myth, resistant to any romantic notions of multicultural nationhood. In drawing together the various actions that occur throughout the text, Eisner employs several highly revealing, and visually sophisticated, graphic signifiers that dramatically underscore the violence and alienation that can result within multi-ethnic communities: a metaphoric emphasis on windows, references to fire, and the presence of “For Sale” or “For Rent” signs. These cyclically recurring images function as a form of illustrated shorthand for the seemingly never-ending attempts of diverse populations to work out their differences. Furthermore, they also serve as formal visual links between the assorted sequences that, taken together, emphasize the social fragmentation of the modern urban landscape.
Art Spiegelman’s Maus: A Survivor’s Tale : A Bibliographic Essay
Authors: Park Hye Su
Published: May 2011

Abstract:
This bibliographic essay on Art Spiegelman’s Maus: A Survivor’s Tale serves as a broad survey of Maus criticism based on ten thematic categories such as trauma, postmemory, generational transmission, and the use of English. As much as this essay examines the wide range of scholarly interests surrounding Maus , it also highlights the problem of repetitive concentration on certain themes that dominates and restricts discussion on the text. This overview of Maus criticism thus not only provides a useful summary of the studies currently available, but also serves as a suggestive guide for future scholars in their attempts to broaden and enrich the field with an eye on expanding the critical discourse.
“You Wouldn’t Shoot Your Fellow Jews”: Jewish Identity & Nostalgia in Joann Sfar’s Klezmer
Authors: Goldberg Nicole Wilkes , Goldberg James
Published: May 2011

While many associate the prewar Ashkenazi community with Fiddler on the Roof ’s “Tradition,” Joann Sfar’s Klezmer: Tales of the Wild East (2006) disrupts this comforting image of community with internal violence, crises of faith, and individual isolation. By redefining nostalgia in Svetlana Boym’s terms of “restorative nostalgia” and “reflective nostalgia,” this essay explores how Sfar’s work challenges restorative methods while embracing reflective nostalgic impulses, valorizing the culture of Diaspora within Judaism. Klezmer music, then, becomes a site for Sfar to examine the Ashkenazi past while questioning the role of Zionism in Jewish identity. Is Jewish identity primarily to be found through communal unity and strong shared objectives? Or is Jewish identity more closely related to the tensions and uncertainties of a Diasporic condition?
High catalytic efficiency and resistance to denaturing in bacterial Rho GTPase-activating proteins
Authors: Litvak Yael , Levin-Klein Rena , Avner Moti , Selinger Zvi
Published: May 2011

Several major bacterial pathogens use the type III secretion system (TTSS) to deliver virulence factors into host cells. Bacterial Rho GTPase activating proteins (RhoGAPs) comprise a remarkable family of type III secreted toxins that modulate cytoskeletal dynamics and manipulate cellular signaling pathways. We show that the RhoGAP activity ofSalmonellaSptP andPseudomonasExoS toxins is resistant to variations in the concentration of NaCl or MgCl2, unlike the known salt dependant nature of the activity of some eukaryotic GAPs such as p190, RanGAP and p120GAP. Furthermore, SptP-GAP and ExoS-GAP display full activity after treatment at 80°C or with 6 murea, which suggests that these protein domains are capable of spontaneous folding into an active state following denaturing such as what might occur upon transit through the TTSS needle. We determined the catalytic activity of bacterial GAPs for Rac1, CDC42 and RhoA GTPases and found that ExoS, in addition toYersiniaYopE andAeromonasAexT toxins, display higher catalytic efficiencies for Rac1 and CDC42 than the known eukaryotic GAPs, making them the most catalytically efficient RhoGAPs known. This study expands our knowledge of the mechanism of action of GAPs and of the ways bacteria mimic host activities and promote catalysis of eukaryotic signaling proteins.
Symmetry mode analysis of the phase transitions in Rb2ZnBr4
Authors: Zúñiga Fco. Javier , Perez-Mato Juan Manuel , Orobengoa Danel , Petricek Václav , Breczewski Tomasz
Published: May 2011

Crystal structures of low temperature phases III, IV and V of Rubidium Zinc Bromide have been determined by single crystal X-ray diffraction at 90 K, 85 K, and 30 K, respectively. The analysis of the structures in terms of symmetry-adapted modes of the high temperature prototype phase permits the identification of the modes responsible for each phase and to assess its thermal evolution. The primary mode responsible for the incommensurate and lock-in phases remains dominant throughout the whole transition sequence, maintaining its structure and slightly increasing its amplitude as temperature decreases. The two monoclinic phases IV and V are presumably due to the instability of a second mode associated with a single active irreducible representation. However, the presence with similar weights of several symmetry-adapted distortions of different symmetry indicates a strong hybridization in phase III of the softer normal modes. A symmetry-mode description of the structures of phase IV and V fully consistent with a simple Landau model, can then only be obtained if phase III is taken as effective parent phase. Besides the insight on the microscopic origin of the different phases, the symmetry modes were used as crystallographic coordinates in the refinement of the structure of phase V. The result shows the advantages of using these non-conventional collective structural parameters instead of individual atomic coordinates. The refinable parameters can be reduced to the amplitudes of those symmetry modes with significant weight in the distortions.
Structural ordering principles in quasi one-dimensional Wigner crystals of the series Na1+x
CuO2 (0 ≤ x ≤ 1)
Authors: Nuss Jürgen , Wedig Ulrich , Jansen Martin
Published: May 2011

The general building principle of the commensurate subset of mixed valent sodium cuprates Na1+x
CuO2 (0 ≤ x ≤ 1) has been revealed. Starting from parent ­NaCuO2, spin doping of the chain of edge sharing CuO4 plaquettes requires to incorporate further sodium ions for charge compensation. The accessible space needed for this purpose is generated by elongating the NaO6 octahedra present in NaCuO2. In this way, from one octahedron two square pyramidal and two tetrahedral sites result, out of which at best one each tetrahedral and square pyramidal site per original octahedron can be occupied, excluding combinations of electrostatically blocked sites. This general building principle has been employed to predict further structure candidates of this series (x = 1/4, 1/3, 2/3, 5/7, 3/4, 1). Density functional calculations (x = 0, 5/7, 3/4, 1) confirm the predicted charge ordering as well as the related structural features. The structure candidates are identified as local minima on the energy landscape.
Large Amplitude Motions in Cyclopentene and 1-Butene: Quantum Chemical Insights into the Ground- and Excited State Potential Energy Surfaces
Authors: Knippenberg Stefan , Kunitski Maksim , Dreuw Andreas
Published: May 2011

The ring-puckering motion in cyclopentene as well as the hindered internal rotation around the central C–C bond in 1-butene have been studied by high-level quantum chemical calculations. Relevant potential energy surfaces of these molecules along these large-amplitude motions are provided as well as rotational constants are given allowing for thorough comparison with recent results from time-resolved femtosecond degenerate four-wave mixing (fs DFWM) spectroscopy. Emphasis is put on the performance of various post-Hartree Fock methods, the required level of electron correlation as well as the basis set quality.
Nonequilibrium NMR Methods for Monitoring Protein and RNA Folding
Authors: Schlepckow Kai , Fürtig Boris , Schwalbe Harald
Published: May 2011

The review introduces to time-resolved NMR spectroscopic investigations of the kinetics of protein and RNA folding. The description of the experimental investigations is discussed in the context of possible kinetic folding pathways showing the extent of information that can be gained from the various kinetic experiments. The review introduces to four different methods to initiate folding reactions in connection with time-resolved NMR experiments and discusses examples of refolding of the model proteinα-lactalbumin and of bistable RNAs.
The Security Dilemma in the U.S.-China Military Space Relationship
Authors: Zhang Baohui
Published: May 2011

The U.S.-China military space relationship has been driven by the security dilemma in international relations. China pursues military space capabilities in part to counter perceived national security threats posed by the U.S. quest for space dominance and missile defense. However, the current strategic adjustment by the Obama administration and the altered situation at the Taiwan Strait have moderated the bilateral security dilemma, offering an opportunity for arms control in outer space.
Neonatal Mortality From Respiratory Distress Syndrome: Lessons for Low-Resource Countries
Authors: Kamath Beena D. , MacGuire Emily R. , McClure Elizabeth M. , Goldenberg Robert L. , Jobe Alan H.
Published: May 2011

Respiratory distress syndrome (RDS) is a major contributor to neonatal mortality worldwide. However, little information is available regarding rates of RDS-specific mortality in low-income countries, and technologies for RDS treatment are used inconsistently in different health care settings. Our objective was to better understand the interventions that have decreased the rates of RDS-specific mortality in high-income countries over the past 60 years. We then estimated the effects on RDS-specific mortality in low-resource settings. Of the sequential introduction of technologies and therapies for RDS, widespread use of oxygen and continuous positive airway pressure were associated with the time periods that demonstrated the greatest decline in RDS-specific mortality. We argue that these 2 interventions applied widely in low-resource settings, with appropriate supportive infrastructure and general newborn care, will have the greatest impact on decreasing neonatal mortality. This historical perspective can inform policy-makers for the prioritization of scarce resources to improve survival rates for newborns worldwide.
Young Maternal Age and Poor Child Development: Predictive Validity From a Birth Cohort
Authors: Chittleborough Catherine R. , Lawlor Debbie A. , Lynch John W.
Published: May 2011

OBJECTIVE:

We aimed to examine the ability of mother's age, and other factors measured during pregnancy (education, financial difficulties, partner status, smoking, and depression), to predict child development outcomes up to age 5 years.

METHODS:

Data were obtained from the Avon Longitudinal Study of Parents and Children (ALSPAC). Poor child development was defined as scoring in the worst 10% of a parent-reported ALSPAC developmental scale (ADS) at 18 months (n = 7546), the Strengths and Difficulties Questionnaire (SDQ) at 47 months (n = 8328), or teacher-reported School Entry Assessment (SEA) scores at 4 to 5 years (n = 7345).

RESULTS:

Only a small proportion of children with poor development had mothers aged younger than 20 years at their birth (3.3%, 6.4%, and 9.2%, for the ADS, SDQ, and SEA, respectively). A greater proportion with each measure of poor development would be identified (48.9%, 63.6%, and 74.4%, respectively) if all 6 predictors were used and a woman had at least 1 of these. Model discrimination was poor using maternal age only (area under the receiver operator characteristic curve ∼0.5 for all 3 outcomes). This improved when all 6 predictors were included in the model (ADS: 0.56; SDQ: 0.66; SEA: 0.67). Calibration also improved with the model including all 6 predictors.

CONCLUSIONS:

Even if programs targeted at teen-aged mothers are successful in improving child development, they will have little impact on population levels of poor child development if young maternal age is the sole or main means of identifying eligibility for the program.
Synthesis of Ultra-Small Si Nano Particle Colloids and Thin Films-High Temperature Single Electronics
Authors: Therrien J. M. , Belomoin G. , Nayfeh M. H.
Published: May 2011

We describe a procedure for dispersing electrochemical etched silicon into a colloid of ultra-small (∼1 nm) silicon nano particles. The particles are then reconstituted on a Si substrate by gentle evaporation from a volatile colloid, forming thin films. When the colloid or the film is excited with UV radiation at 355 nm, strong blue emission band at 390 nm is observable with the naked eye in room light. Two-terminal I-V spectra of the deposited film, taken using a scanning tunneling microscope (STM), show a single regular conductance resonance at a spacing of 0.25-0.30 eV, consistent with single electron charging. However, under light irradiation, we observe a second regular resonance, for negative tip biasing less than -1 eV, that modulates the charging structure at ∼ 1.0 eV period, consistent with the particle's quantum energy level spacing. This paves the way for operation of high-temperature Si-based single electron devices.
Fabrication Methods for Au Nanocluster Devices
Authors: Snow A.W. , Ancona M.G. , Kruppa W. , Park D. , Boos J.B. , Jernigan G.G.
Published: May 2011

The deposition chemistry of hexanethiol-stabilized gold nanoclusters self-assembled on Au and SiO2 surfaces by reaction with a series of α,ω-alkanedithiols is studied using X-ray photoelectron spectroscopy and electrical measurements. Testing of micron-scale devices shows that high conductivity is achieved only for a narrow range of dithiols and with a sharp efficiency threshold. Nanoscale devices exhibit similar behavior though with much evidence of “granularity” in the deposition.
Organometallic Synthesis and Spectroscopic Characterization of Manganese Doped CdSe Nanocrystals
Authors: Mikulec Frederic V. , Kuno Masaru , Bennati Marina , Hall Dennis A. , Griffin Robert G. , Bawendi Moungi G.
Published: May 2011

For CdSe quantum dots (QDs) produced via high temperature pyrolysis in trioctylphosphine oxide (TOPO), a MnSe precursor such as Mn2(μ-SeMe)2(CO)8appears to be necessary to successfully incorporate low levels of Mn. A simple etching experiment and electron paramagnetic resonance (EPR) measurements reveal that most of the dopant atoms reside in the surface layers of the inorganic lattice. The dopant dramatically affects 113Cd solid state NMR spectra; the observed paramagnetic shift and decreased longitudinal relaxation time reproduce bulk material behavior. Paramagnetic atoms in QDs generate large effective magnetic fields, which implies that magneto-optical experiments can be performed simply by doping. Results from fluorescence line narrowing (FLN) studies on Mn doped CdSe QDs mirror previous findings on undoped QDs in an external magnetic field. Experimental fitting of photoluminescence excitation (PLE) spectra of doped QDs reveals that the effective absorption lineshape contains a new feature which is believed to be a previously unobserved – but theoretically predicted – optically dark fine structure state.
Transport Calculations in Molecular Devices from First Principles
Authors: Ventr M. Di , Langa D. , Pantelid S.T.
Published: May 2011

For molecular electronics, Boltzmann's equation is no longer valid for simulating device characteristics. We resent the first fully ab initio simulation of a molecular device that has already been studied ex erimentally, namely a benzene-1,4-dithiolate molecule between gold electrodes. The theoretical I-V curve has the same overall sha e as the ex erimental curve —reflecting the electronic structure of the molecule in the resence of the electric field — but the absolute value of the current is very sensitive to contact chemistry and geometry. In articular the resence ol a single gold atom between the molecule and the electrode surface reduces the conductance by more than an order of magnitude. Re lacement of the single gold atom by an aluminum atom, whose p orbitals cou le more effectively to the molecule's T orbitals, increases the conductance by about an order of magnitude. We have also studied the olarization effects induced by a third terminal (gate) on the I-V characteristics of the above device. In articular, we have found that current gain due to the gate bias can be achieved at reasonable gate fields. Finally the effect of current-induced forces on the device will be discussed.
Electronic Structure of Organic/Metal Interfaces Studied by UPS and Kelvin Probe
Authors: Seki Kazuhiko , Oji Hiroshi , Ito Eisuke , Yoshimura Daisuke , Hayashi Naoki , Ouchi Yukio , Ishii Hisao
Published: May 2011

The interfaces of organic materials with other solids play important roles in the function of various organic devices such as organic light-emitting diodes (OLEDs), spectral sensitization in photography, organic solar cells, and electrophotography. Also they should be important in future molecular devices, both in the central part of the device and at the connection with outside circuits. However, serious experimental examination of such interfaces has started only recently. In this talk we focus our attention on the organic/metal interfaces, and summarize our understanding about (1) the energy level alignment right at the interface, and (2) possible band bending within an organic layer, mainly using the techniques of UV photoemission spectroscopy (UPS) and Kelvin probe method. As for (1), the formation of electric dipole layer was observed in most organic/metal interfaces, and its origin is discussed. As for (2), recent examination of the existence/absence of band bending in ultrahigh vacuum will be reported. It is also pointed out that there can be much effects of (i) atmosphere at sample preparation and measurements, and (2) chemistry and interdiffusion at the interface.
Effects of Φ-Stacking on the Absorption and Emission of Light by Conjugated Polymers and Oligomers
Authors: Curtis M. David , Koren Amy , Kampf Jeff W.
Published: May 2011

We have determined the crystal structures of regioregular HH-TT oligomers with a variety of side chains, including hydroxy-bearing side chains capable of H-bonding. The H-bonding orders the molecular packing into infinite 2-D sheets of Φ-stacks. In these H-bonded sheets, the Φ-stacks are insulated from each other by the aliphatic side chains and form one-dimensional “wires”. In contrast, the structures of similar oligomers that do not have H-bonded side-chains feature a structure in which neighboring Φ-stacks in are in contact (“shorted wires”). The effects of these differing molecular arrangements on the spectral properties and exciton splitting are discussed.
Effect of ITO Carrier Concentration on the Performance of Organic Light-Emitting Diodes
Authors: Zhu Furong , Zhang Keran , Huan C. H. A. , Wee A.T.S. , Guenther Ewald , Jin Chua Soo
Published: May 2011

The indium tin oxide (ITO) anodes for organic light emitting diode (OLED) were made from an oxidised target with In2O3 and SnO2 in a weight proportion of 9:1 using the RF magnetron sputtering method. The comparable ITO anodes with different carrier concentrations were prepared by varying the hydrogen partial pressure during film deposition. The current-luminance-voltage characteristics of the devices indicated that a high carrier concentration in ITO plays a role in improving OLED performance. A maximum efficiency of 3.8 cd/A was achieved when an ITO anode with a higher carrier concentration of 9×1020 cm−3 was used in a fluorene based OLED. This efficiency is about 1.5 times higher than that of an identical device made with an ITO anode having a lower carrier concentration of 5×1020 cm−3. The increase in electroluminescent efficie ncy reflects an enhanced hole-injection in the device. We consider that enhanced hole injection is due to the reduced band bending in ITO when it has a high carrier concentration
Design and Synthesis of Highly Efficient Nonlinear Optical Chromophores
Authors: Wu Xiaoming , Jen Alex K.-Y.
Published: May 2011

Two series of highly hyperpolarizable nonlinear optical (NLO) chromophores, containing perfluoroaryl dicyanovinyl and phenyl tetracyanobutadienyl acceptors, have been designed and synthesized. These chromophores show good thermal and chemical stability. The 3D conformational structures, confirmed by computational modeling, enhance polymer matrix compatibility and decrease optical loss of the polymer films. The guest-host polymers of the chromophores show large electro-optical activities.
Multi-Mode Emission from an ALQ Based Optical Microcavity
Authors: Feng Jimeng , Liu Xingyuan
Published: May 2011

Organic light emitting device (OLED) with a microcavity structure has been fabricated. A kind of chirped distributed Bragg reflector (DBR) and a metal Al film was used as the two reflectors of the microcavity. A multimode light emission was achieved due to the structure of the microcavity. The emission peaks of the microcavity were located at 476nm, 520nm, 597nm and 626nm, respectively.
Excitons in Segmented Polymers for High Photo- and Electro-Luminesence Efficiency
Authors: Epstein Arthur J. , Sun Runguang , Wang Daike , Gustafson Terry L. , Kyllo Erica M. , Delucia Frank C. , Zheng Qianbing
Published: May 2011

The photoluminesence (PL) quantum efficiency of poly(p-phenylene vinylene) (PPV) varies with preparation and processing. We report the achievement of nearly 100% PL quantum efficiency through design and synthesis of alternating rigid conjugated segments of dimethoxy -PV (three dimethoxy -phenyl and two vinyl units) and flexible nonconjugated segments along the polymer backbone. There is enhanced solubility in desired solvents and increased interchain separation through the incorporation of the methoxy sidegroups, forming poly [1,6-hexanedioxy -2,6-dimethoxy-1,4-phenylene]-1,2-ethenylene-[3,6-dimethoxy-1,4-phenylene]-1,2-ethenylene-[3,5-dimethoxy-1,4-phenylene], or GDBBC. The nearly temperature-independence of the PL decay at different emission wavelengths of the alternating block co-polymer (ABC) shows that the excitons are highly localized due to the blocking by non-conjugated segments as well as due to increased interchain separation due to the methoxy sidegroups. The contrasting temperature- and time- dependent results for the corresponding PV oligomer and PPV, supports the role of reduced exciton migration in achieving high quantum efficiency. The results are compared to the exciton confinement at the interface of light emitting electron and hole transporting polymers, forming an exciplex, for which the luminescence decay is also temperature independent. Electroluminescent devices using GDBBC as the lightemitting layer and incorporating poly[1-phenyl-2-(p-n-carbazolylphenyl) acetylene], (PDPA-Cz), as hole transporting layer, in the structure ITO/PDPACz/GDBBC/Alq/MgAg have ~1% external quantum efficiency with green emission from the GDBBC. EL devices based on exciplex emission are also discussed.
Magnetic Orientation of Polymers A Novel Technique of Controlling Birefringence
Authors: Kimura Tsunehisa , Ito Eiko
Published: May 2011

Magnetic -field induced orientation of crystalline polymers recently reported by our group is briefly summarized and a possible application of this new phenomenon is presented. We have recently reported a new finding that crystalline polymers including poly(ethylene-2,6-naphthalate), isotactic polystyrene, isotactic polypropylene, poly(ethylene terephthalate), and paraffin align under a strong magnetic field during the phase transition from melt to crystal. We have assumed that some ordered structure, most likely liquid-crystalline-like structure, appearing transiently during the transition is responsible for this phenomenon. Aligned films were transparent and exhibited retardation of several hundred nanometers, suggesting a possible application to fabrication of materials demanded for optical use.
Environmental Effects on the Electronic Spectra of Electrostatically Assembled Layers of Conjugated Polymers
Authors: Kim Myunghwan , Sandman Daniel J.
Published: May 2011

Conjugated polyelectrolytes, poly[2-(3-thienyl)-ethanolhydroxycarbonylmethylurethane] (HPURET) and PDA from 5,7-dodecadiyn-1,12-bis-(hydroxycarbonylmethylurethane) (HP4BCMU), were processed by programmed electrostatic assembly, respectively, with two different polycations that have significantly different refractive indices – one is poly(diallydimethylammonium) chloride (PDADMAC), the other poly(4-vinyl pyridine) quaternized with dimethylsulfate (QPVP). The optical properties of these conjugated polymers have been studied with particular attention to local environmental effects and adaption (post-assembly-processing). The electronic absorption spectra of these assemblies were dependent on the details of the assembly process.
Langmuir-Blodgett Film of a Processable Polydiacetylene with Tricyanovinyldialkylaniline Chromophore
Authors: Lee D.-C. , Li L. , Samuelson L. A. , Sandman D. J.
Published: May 2011

A soluble and processable polydiacetylene (PDA) with functionalizable N,N-dialkylaniline and glutamate ester substituted alkylurethane side groups was synthesized. This PDA was further reacted with tetracyanoethylene to effect postpolymerization functionalization. This new strategy further functionalizes conjugated polymers and introduces a tricyanovinyl (TCV)-aniline chromophore. The resulting polymer was soluble in common organic solvents. Asymmetric multilayers of the tricyanovinylated PDA were fabricated using the Langmuir-Blodgett (LB) technique. Thickness, visible absorption, and second harmonic (SH) intensity were found to increase linearly as a function of the number of layers. Polarized UV-visible and IR studies revealed that the main chain preferentially orients vertical to the compression direction with out-of-plane orientation of the TCV-aniline group with respect to the glass substrate. The resonant enhanced second-order nonlinear optical (NLO) coefficient (d33) of the 20 LB layers was found to be 21 pm/V at 1.064 µm, while no SHG signal was observed for cast or spincoated films.
Film Growth, by Seeded Supersonic Beams, of Thiophene-Based Oligomers with Controlled Optical, Structural and Morphological Properties
Authors: Toccoli Tullio , Ferrari Maurizio , Ronchin Sabina , Podestà Alessandro , Milani Paolo , Iannotta Salvatore
Published: May 2011

A novel approach for the deposition of high quality films of oligothiophenes has been developed. It is based on an original seeded supersonic molecular beam combined with a UHV deposition chamber. This method gives an unprecedented control on film properties. Several T4 films under different beams conditions have been prepared and characterized by optical absorption, photoluminescence and TMAFM. Morphology, structure and optical response are controlled by the beam's parameters. Highly ordered films, up to several hundreds of nm thick, show well resolved vibronic structures in low temperatures PL as only the best published data on films a few monolayers thick do.
Fluid Mechanics Model and Analysis for the Photofabrication of Surface Relief Grating on Azo Polymers
Authors: Fukuda Takashi , Matsuda Hiro , Sumaru Kimio , Yamanaka Tadae
Published: May 2011

The mass transporting properties of the surface relief grating (SRG) photofabrication on azobenzene polymer films is discussed precisely using an existing fluid mechanics model. Formulation for the SRG inscription rate is derived analytically from Navier-Stokes equation. In consequence, the dependence of inscription rate of the SRG on the experimental and geometrical parameters was explained very well by the model. The photoinduced surface deformation with an onedimensional Gaussian laser beam was also carried out in order to establish the validity and the generality of our fluid mechanics model. The experimentally obtained surface deformation profile is well reproduced by the theoretical model generalized for arbitrary force field profile.
The Influence of Ordering on the Photoinduced Charge Transfer in Composites of Phenyl-type Substituted Polythiophenes with Methanofullerenes
Authors: Brabec Christoph J. , Winder Christoph , Scharber Markus C. , Sariciftci N. Serdar , Andersson Mats R. , Inganäs Olle , Hummelen Jan C.
Published: May 2011

Regioregular polythiophenes baring 3-(p-methoxyethoxyethoxy)-phenyl substituents (PEOPT) show high photoluminescence efficiencies. Exposing thin films of this polymer to vapors of chloroform or annealing them by heat treatment results in a red shift of the absorption maximum due to solvent or heat induced ordering which gives rise to more planar conformations. The fact, that annealed thin films of PEOPT exhibit absorption edges at relatively low energies and thus have an enhanced spectral range makes them suitable for use in photodiodes / solar cells. The photoinduced charge generation efficiency in PEOPT is significantly enhanced by the addition of a strong electron acceptor like fullerene, as observed by quenching of the luminescence and by photoinduced absorption measurements in the infrared and UV-Vis regime. The efficiency of the photoinduced charge transfer from PEOPT to a methanofullerene is found to depend on the ordering of PEOPT in thin films.
Linear and Nonlinear Optical Properties of Novel Ionic Chromophores
Authors: Duan Xuan-Ming , Wada Tatsuo , Okada Shuji , Oikawa Hidetoshi , Matsuda Hiro , Sasabe Hiroyuki , Nakanishi Hachiro
Published: May 2011

A series of novel ionic chromophores consisting of a carbazole moiety and pyridinium rings connected by a double bond have been designed and synthesized as nonlinear optical materials. Their linear and nonlinear optical properties were investigated by semiempirical calculation and experiment. The absorption maximum wavelengths (lmax) of these ionic chromophores showed shifting to longer wavelength region than their corresponding electrically neutral compounds. These ionic chromophores possess large first hyperpolarizabilities (b).
Multifunctional Dendrimers Incorporating Diphenylaminopolyenylic Chromophores
Authors: Ashworth K. , Reeves B. , Frost A. , Spangler C. , Sapochak L. , Padmaperuma A. , Schmett G.
Published: May 2011

We have previously shown that diphenylpolyenes incorporating diphenylamino donor substituents form exceptionally stable bipolaronic dications in solution, even at the bis-(diphenylamino)-E-stilbene level, whereas most previously known polyenylic bipolarons were unstable at lengths shorter than the tetraene1. Most recently we have also demonstrated that replacement of one of the diphenylamino substituents in the stilbene substrate with a N-(hydroxyethyl), N-ethylaminophenyl group yields a functionalized polyene that can easily be attached to PMMA as a pendant group, or to 3,5-dihydroxy-benzyl alcohol to form reactive dendrons2. These functionalized materials also form extremely stable bipolarons and are intensely fluorescent. In this presentation we will discuss the formation of G-0 dendrimers incorporating a series of polyenes related to the stilbene structure, and possible photonic applications.
Inorganic-Organic Molecular Based Magnets
Authors: Lescop Christophe , Luneau Dominique , Rey Paul
Published: May 2011

This paper reports on a series of compounds based on Mn(II) complexes with nitronyl nitroxide free radicals which afford layered structures and exhibiting spontaneous magnetization up to 50K.
Photo and Electroluminescent Properties of a Porphyrin-Poly(p-Phenylene Vinylene) Derivative
Authors: Morgado J. , Iqbal R. , Yahioglu G. , Milgrom L. R. , Moratti S. C. , Holmes A. B. , Friend R. H. , Cacialli F.
Published: May 2011

The solid state luminescent properties of new statistical copolymers of 2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene and a porphyrin-substituted phenylene vinylene are reported. The photoluminescence, PL, emission shows an efficient energy transfer to the porphyrin, in spite of the small absorption coefficient of the porphyrin in the wavelength range of the poly [2-methoxy-5-(2'- ethylhexyloxy)-1,4-phenylene vinylene], MEH-PPV, emission. At a porphyrin content of 0.25%, by weight, the emission is already dominated by the porphyrin. The PL efficiency of these copolymers is significantly reduced from the value of 13% for MEH-PPV down to 3% for the copolymer with 10.84% of porphyrin. Efficient energy transfer is also observed in the emission spectra of light-emitting diodes.
Intermolecular Coupling Enhancement of the Molecular Hyperpolarizability in Multi-chromophoric Dipolar Dendrons
Authors: Yokoyama Shiyoshi , Otomo Akira , Mashiko Shinro
Published: May 2011

Nonlinear optical dendritic macromolecules, called “azobenzene dendrons”, having a branching structure modified with a second-order nonlinear optical chromophore has been synthesized. An electron donor and acceptor azobenzene chromophore having a large molecular hyperpolarizability of β0=150E-30 esu, was chosen. The electronic structure of synthesized dendrons, which were expected to become dipolar due to their intermolecular attractive interaction, was proven by second-order nonlienar optical properties. The molecular hyperpolarizabilities of azobenzene dendrons were measured by the hypr-Rayleigh scattering technique. The highest molecular hyperpoalrizability was found to be 3,010E-30 esu for an azobenzene dendron having 15 chromophoric unit, where each chromophore coherently contribute to the second harmonic generation. This level of the molecular hyperpolarizability was much larger than that for a monomeric azobenzene chromophore.
Synthesis and Photo-Bleaching of Epoxy-Based Nonlinear Optical Polymers Containing Triene Chromophores
Authors: De B. B. , Kumar J. , Tripathy S. K. , Balasubramanian S. , Chittibabu K. G. , Li L.
Published: May 2011

Bis(diglycidyl)ether of bisphenol-A-aniline (BP-AN) based second-order nonlinear optical (NLO) polymers containing triene chromophores have been developed through post-polymer functionalization reactions. One-pot aldol condensation reaction of dicyanomethylidene functionalized verbenone as well as isophorone compounds with aldehyde functionalized BP-AN polymer enabled the introduction of various chromophore moieties with high degree of functionalization. These polymers were studied using various structural (1H NMR, FTIR), linear (UV-Vis) and NLO characterization techniques. A d33 value of ca. 139 pm/V at 1.064 µm was determined for a representative polymer containing verbenone unit. We have observed fast photo-bleaching in these polymers. Detailed studies on the photophysical properties of this class of materials have been carried out using various analytical techniques, the structure-properties relationship and photo-bleaching mechanisms will be presented.
Control of Second-Order Nonlinear Optical Susceptibility in Ionically Self-Assembled Films by pH and Ionic Strength
Authors: Figura C. , Neyman P.J. , Marciu D. , Brands C. , Murray M.A. , Hair S. , Miller M.B. , Davis R.M. , Heflin J.R.
Published: May 2011

Ionically self-assembled monolayers have been recently shown to spontaneously produce the noncentrosymmetric ordering that is required for a second order nonlinear optical (NLO) response. The precise thickness of each monolayer is determined by variables such as the pH and ionic strength of the immersion solutions. We show here that the relationship between polymer conformation and layer thickness dramatically affects the magnitude of the NLO response. The largest χ(2) values are found in the thinnest films, indicating that the NLO response is determined primarily by chromophores located at the layer interfaces, as opposed to those within the bulk of a layer.
The Interconnection Between Efficiency and Morphology of Two Component Systems in Plastic Solar Cells
Authors: Padinger Franz , Gebeyehu Desta , Brabec Christoph J. , Fromherz Thomas , Sariciftci N. Serdar , Hummelen Jan C.
Published: May 2011

Using the ultrafast photoinduced electron transfer with long-living charge separation in the conjugated polymer/fullerene thin films, photovoltaic devices have been fabricated. The photoinduced charge separation happens with internal quantum efficiency near unity. The performance of such “bulk heterojunction” photovoltaic devices is critically dependent on the transport properties of the interpenetrating network. The influence of the variation of different donor / acceptor materials on the sample morphology is monitored by atomic force microscopy (AFM), while I/V characteristics have been studied to evaluate the conversion efficiency.
High Mobilities in Organic Molecular Crystals
Authors: Schön Jan Hendrik , Berg Steffen , Kloc Christian , Batlogg Bertram
Published: May 2011

The charge transport in high quality single crystals of various organic molecular semiconductors is investigated. Band-like motion in delocalized states is observed in various polyacene and oligothiophene single crystals. The electric field dependence of the mobility is ascribed to acoustic phonon scattering. Furthermore, hot carrier effects can be observed at low temperatures and high electric fields. Band-like transport changes over to hopping motion when the effective bandwidth shrinks, i.e. at high temperatures or in crystallographic directions of small molecular orbital overlap.
Facile Deposition Processes for Semiconducting Molecular Solids
Authors: Katz H.E. , Li W. , Lovinger A.J. , Raju V.R. , King J.'A. , Lin Y.-Y. , Dodabalapur A. , Bao Z. , Rogers J.
Published: May 2011

Films of end-substituted dihexyl-α-sexithiophene and –quinquethiophene were cast from solutions in aromatic solvents onto SiO2 and polyimide dielectrics at moderately elevated temperatures and reduced pressure. X-ray diffraction showed perpendicular orientation for most samples, while electron and optical microscopy revealed considerable variations in grain sizes, spacings, and uniformity depending on deposition conditions. For favorable morphologies, thin film transistor (TFT) mobilities were as high as those typically obtained from vacuum-deposited films, in the range of 0.01-0.2 cm2/Vs, with on/off ratios >1000 in accumulation mode.
Remedial Action for Radioactive Waste Rock Piles in China
Authors: Zhangru Chen , Yuanxin Jin , Lanying Song , Qingyan Wu
Published: May 2011

The Chinese government has conducted remedial action for radioactive waste rock piles since 1990. The radioactive waste rocks produced in the course of geological exploration of uranium deposits are widely distributed over several hundreds of locations in more than 20 provinces in China.

The following remedial actions for radioactive waste rock piles have been undertaken in China:

1. Protecting dams for stabilizing the piles have been built. A total length of about 50,000 m of these dams has been completed.

2. Soil layers have been emplaced on the radioactive waste rock piles. The focus of the action is to eliminate the radiation harmful to public health. A total area of 750,000 square meters of soil ahs been placed on the piles in China.

3. Radioactive waste rock piles have been vegetated. Aesthetic shaping of the landscape in the exploratory district of the uranium deposits is our expectant goal. A total area of about 560,000 square meters of vegetation has been placed on the soil covering the piles.

Through these remedial actions, the environmental situation has been extensively improved in the remedial districts. The individual annual effective dose equivalent is less than 1 Sv/a. The radon emission rate is less than 20 pCi/m2.s. The gamma ray external exposure rate has been greatly reduced.