bluuebunny/crossref_metadata_2025 huggingface dataset:
A Distribution‐Free Multivariate Control Chart for Phase I Applications
Authors: Cheng Ching‐Ren , Shiau Jyh‐Jen Horng
Published: October 2014

The purpose of this paper is to provide a novel distribution‐free control chart for monitoring the location parameter vector of a multivariate process in phase I analysis. To be robust to the process distribution, the spatial sign statistic that defines the multivariate direction of an observation is used to construct a Shewhart‐type control chart for detecting out‐of‐control observations in historical phase I data. The proposed control chart is distribution free in the sense that the false‐positive rate (or false alarm rate), the proportion of wrongly classified in‐control samples, can be controlled at the specified value for elliptical‐direction distributions. In addition, we demonstrate through simulation studies that the false‐positive rate of the proposed chart is robust to the shift size of the out‐of‐control condition if we only delete the most extreme out‐of‐control observation at each iteration of phase I analysis. Compared with the traditional Hotelling's T2 control chart and some of its robust versions, the proposed chart is generally more powerful in detecting out‐of‐control observations and more robust to the normality assumption. Copyright © 2014 John Wiley & Sons, Ltd.
Sustaining school partnerships: the context of cross‐sectoral collaboration between schools in a separate education system in Northern Ireland
Authors: Duffy Gavin , Gallagher Tony
Published: October 2014

This study explores the current understanding of cross‐sectoral collaboration between schools in a divided society. The paper provides the context surrounding inter‐school collaboration in Northern Ireland then presents findings based on a qualitative study of five post‐primary partnerships made up of schools from the various sectors in Northern Ireland (maintained/Catholic, controlled/Protestant and integrated sectors). Participants in the study are teachers and school leaders. Evidence from this study reveals a number of things: despite a separate education system made up of different sectors, schools on an inter‐sectoral basis are willing to collaborate and those represented in this study appeared disposed to sustain partnership activities; schools recognised that collaboration and partnership while beset with a number of logistical challenges, is also beneficial for pupils and institutions. In all cases there remained evidence of sustainable collaborative practice; although some of this was more developed in some partnerships than in others. In effect this paper concludes by recognising that schools do require some level of funding to sustain partnership working but that sustainability should not be couched entirely around these terms; rather, sustainability is about creating the right conditions to allow schools to develop effective and strong partnerships. These conditions are outlined in the latter stages of this paper.
CAPTCHA and its Alternatives: A Review
Authors: Moradi Mohammad , Keyvanpour MohammadReza
Published: October 2014

Nowadays, because of the undeniable impact of the Internet on all aspects of human life, security preserving has received more attention. To reach an acceptable level of security, Completely Automatic Public Turing test to tell Computer and Human Apart or simply CAPTCHA as a security preserving tool has been tailored for situations that need to prevent bots from doing a specific action; for example, signing up and downloading. Simultaneously, it should be also designed in such a way to allow humans to perform the same action. Despite its advantageous applications, there are several important issues such as security, usability, and accessibility that make its use controversial. In this paper, attempts were made to do a comprehensive review on various aspects and state‐of‐the‐art of CAPTCHA in general and its alternatives in particular to help researchers easily focus on specific issues for the sake of proposing new solutions and ideas. Regarding the advancement in CAPTCHA development, new classifications were proposed to categorize different variations of CAPTCHAs and their problems and then compare them. Moreover, different types of CAPTCHAs' alternatives were classified and evaluated by introducing several proposed measures. This evaluation could come in handy for future studies that aim to develop new techniques for overcoming current deficiencies. Copyright © 2014 John Wiley & Sons, Ltd.
Short‐Term Efficacy of Sacroiliac Joint Corticosteroid Injection Based on Arthrographic Contrast Patterns
Authors: Scholten Paul M. , Patel Shounuck I. , Christos Paul J. , Singh Jaspal R.
Published: October 2014

Objective

To determine the relationship between sacroiliac joint (SIJ) contrast dispersal patterns during SIJ corticosteroid injection and pain relief at 2 and 8 weeks after the procedure. The association between the number of positive provocative SIJ physical examination maneuvers (minimum of one in all patients undergoing SIJ injection) and the patient's response to the intervention was also assessed.

Design

Retrospective chart review.

Setting

Academic outpatient musculoskeletal practice.

Patients

Fifty‐four subjects who underwent therapeutic SIJ corticosteroid injection were screened for inclusion; 49 subjects were included in the final analysis.

Methods

A retrospective review of electronic medical records identified patients who underwent SIJ corticosteroid injection. Fluoroscopic contrast flow patterns were categorized as type I (intra‐articular injection with cephalad extension within the SIJ) or type II (intra‐articular injection with poor cephalad extension). Self‐reported numeric pain rating scale (NPRS) values at the time of injection and 2 and 8 weeks after the procedure were recorded. The number of positive provocative SIJ physical examination maneuvers at the time of the initial evaluation was also recorded.

Main Outcome Measures

The primary outcome measure was the effect of contrast patterns (type I or type II) on change in NPRS values at 2 weeks and 8 weeks after the injection. The secondary outcome measure was the association between the number of positive provocative SIJ physical examination maneuvers and decrease in the level of pain after the procedure.

Results

At 2 weeks after the procedure, type I subjects demonstrated a significantly lower mean NPRS value compared with type II subjects (2.8 ± 1.4 versus 3.8 ± 1.6, respectively, P = .02). No statistically significant difference was observed at 8 weeks after the procedure. NPRS values were significantly reduced both at 2 weeks and 8 weeks, compared with baseline, in both subjects identified as having type I flow and those with type II flow (P < .0001 for all within‐group comparisons).

Conclusions

Fluoroscopically guided corticosteroid injections into the SIJ joint are effective in decreasing NPRS values in patients with SIJ‐mediated pain. Delivery of corticosteroid to the superior portion of the SIJ leads to a greater reduction in pain at 2 weeks, but not at 8 weeks. Patients with at least one positive provocative maneuver should benefit from an intra‐articular corticosteroid injection.
Academic resistance to quality assurance processes in higher education in the UK
Authors: Lucas Lisa
Published: October 2014

The focus of this article is on academic resistance to quality assurance processes that have developed within UK higher education in relation to both research and teaching. These quality processes are often seen as forms of disciplining technologies (Blackmore, 2009) and are arguably an important part of the means by which new public management has been introduced to the sector. They have been perceived to monitor and control academic work in relation to teaching and research within UK universities over the last 20 years or so. However, this article attempts to look at the complexity of academic reactions to these processes and the ways in which academics situated within particular contexts might challenge and resist the discourses and subject positions that are being offered to them Thomas and Davies (2005). Following the work of Graham (2011) and Hyatt (2013) a Foucauldian informed critical discourse analysis is used to examine two critical case studies of resistance to both the quality assurance processes for teaching and the assessment and evaluation of university research work.
The evolution of pentameric ligand-gated ion-channels and the changing family of anthelmintic drug targets
Authors: BEECH ROBIN N. , NEVEU CÉDRIC
Published: October 2014

Pentameric ligand-gated ion-channels rapidly transduce synaptic neurotransmitter signals to an electrical response in post-synaptic neuronal or muscle cells and control the neuromusculature of a majority of multicellular animals. A wide range of pharmaceuticals target these receptors including ethanol, nicotine, anti-depressants and other mood regulating drugs, compounds that control pain and mobility and are targeted by a majority of anthelmintic drugs used to control parasitic infection of humans and livestock. Major advances have been made in recent years to our understanding of the structure, function, activity and the profile of compounds that can activate specific receptors. It is becoming clear that these anthelmintic drug targets are not fixed, but differ in significant details from one nematode species to another. Here we review what is known about the evolution of the pentameric ligand-gated ion-channels, paying particular attention to the nematodes, how we can infer the origins of such receptors and understand the factors that determine how they change both over time and from one species to another. Using this knowledge provides a biological framework in which to understand these important drug targets and avenues to identify new receptors and aid the search for new anthelmintic drugs.
Recent large-scale colonisation of southern pine plantations by Swainson’s WarblerLimnothlypis swainsonii
Authors: GRAVES GARY R.
Published: October 2014

Swainson’s WarblerLimnothlypis swainsoniiis a secretive species of high conservation concern with an estimated global breeding population of 90,000 individuals sparsely distributed across 15 states in the south-eastern United States. Its status as one of the rarest songbirds in North America has been attributed to the scarcity of breeding and wintering habitat. Although the warbler was once thought to be a habitat specialist of lowland canebrakes, it is now known to breed in a wide spectrum of broadleaf forest habitats linked by the common denominator of high stem densities and visual screening in the understorey stratum. Scattered instances of a fundamental habitat expansion into early seral stages of even-aged pine plantations were first observed in east Texas in 1992. Here I report that the colonisation of pine plantations is not only locally extensive in Texas but that it is widespread on the coastal plain eastward to south-eastern Virginia. During two decades of field surveys, breeding territories (n =297) were documented in young pine plantations in 95 counties and parishes in 10 states. Occupied plantations were mostly 6–12 m tall (median = 7.5 m), corresponding to 8–15 years after planting. Soil type and the presence of interspersed broadleaf vegetation may be important co-factors in plantation occupancy. The chronology of this breeding niche expansion is poorly known but it appears to have occurred after the 1970s, most likely catalysed by the rapid growth of pine plantation silviculture after World War II. As late as 2001, it was believed that > 90% of the breeding population occurred in broadleaf floodplain forest. The recent range-wide colonisation of pine plantations changes the calculus. If the current trend continues, forest lands managed for short-rotation pine plantations will support the majority of breeding populations by the end of the 21stcentury.
Associations of serum 25-hydroxycholecalciferol and parathyroid hormone with serum lipids differ by sex and vitamin D status
Authors: Jungert Alexandra , Roth Heinz J , Neuhäuser-Berthold Monika
Published: October 2014

Objective

Although emerging evidence indicates an association between vitamin D and serum lipids, the data are still inconsistent. The purpose of the present study was to investigate whether 25-hydroxycholecalciferol (25-hydroxyvitamin D3; 25(OH)D3) or intact parathyroid hormone (iPTH) was independently related to serum lipids in elderly women and men.

Design

Cross-sectional study. Fasting serum levels of 25(OH)D3, iPTH, TAG, total cholesterol (TC), HDL cholesterol (HDL-C) and LDL cholesterol (LDL-C) were assessed. Body composition was measured by bioelectrical impedance analysis. Lifestyle factors, such as nutrient intake, time spent outdoors, physical activity, smoking, supplement intake and medication, were assessed by questionnaires. Multiple regression analyses were performed to examine associations of 25(OH)D3and iPTH with serum lipids.

Setting

Giessen, Germany.

Subjects

One hundred and ninety-three well-functioning German elderly aged 66–96 years.

Results

After adjusting for age, body fat, physical activity, smoking, alcohol intake, lipid-modifying drugs and either iPTH or 25(OH)D3, 25(OH)D3was a predictor of TAG (standardised coefficient beta (β)=–0·180), HDL-C (β=0·197), LDL-C:HDL-C (β=−0·298) and TC:HDL-C (β=−0·302) in women, whereas iPTH was a predictor of HDL-C (β=−0·297) in men. In sub-analysis, associations between 25(OH)D3and TC (β=−0·252), HDL-C (β=0·230), LDL-C (β=−0·324), LDL-C:HDL-C (β=−0·412) and TC:HDL-C (β=−0·380) were found in women with 25(OH)D3concentrations above or equal the median vitamin D status (62·3 nmol/l), but not in women with lower 25(OH)D3concentrations.

Conclusions

In the elderly, associations of 25(OH)D3and iPTH with serum lipids may differ by sex and may require a vitamin D status above 62 nmol/l.
Cosmic radiation exposure of biological test systems during the EXPOSE-R mission
Authors: Berger Thomas , Hajek Michael , Bilski Pawel , Reitz Günther
Published: October 2014

In the frame of the EXPOSE-R mission outside the Russian Zvezda Module of the International Space Station (ISS) passive thermoluminescence dosimeters were applied to measure the radiation exposure of biological samples. The detectors were located beneath the sample carriers to determine the dose levels for maximum shielding. The dose measured beneath the sample carriers varied between 317 ± 10 and 230 ± 2 mGy, which amount to an average dose rate of 381 ± 12 and 276 ± 2 μGy d−1. These values are close to those assessed for the interior of the ISS and reflect the high shielding of the biological experiments within the EXPOSE-R facility. As a consequence of the high shielding (several g cm−2), the biological samples were predominantly exposed to galactic cosmic heavy ions and trapped protons in the Earth's radiation belts, whereas the trapped electrons did not reach the samples.
The impact of organic cotton cultivation on the livelihood of smallholder farmers in Meatu district, Tanzania
Authors: Altenbuchner Christine , Larcher Manuela , Vogel Stefan
Published: October 2014

In Tanzania, as in many developing countries, cotton is an important source of income for smallholder farmers but also causes various negative effects through high pesticide and intensive land use. To overcome these effects organic agriculture is promoted by different non-governmental organizations (NGOs) and companies. This study examines how organic cotton cultivation influences the livelihood of smallholder farmers in rural Tanzania and focuses on three areas: (1) the motivation to change from conventional to organic farming, (2) experiences and challenges of farmers in the conversion process as well as in the period following the conversion, and (3) the attitude and perceptions of farmers toward organic farming in general. Qualitative interviews with organic farmers in Meatu district in the north of Tanzania, as well as expert interviews, were conducted and observations were made. Results show that although the organic price premium is an important incentive for farmers to convert to organic agriculture, access to training and advisory service are even more important, as no other sufficient agriculture extension service is available in the region. Due to a high level of poverty in the region, environmental motivations for conversion are not in the foreground. Furthermore, the study shows that organic farming can contribute greatly to the improvement of livelihoods in the region (improved soil fertility, increased yields and income, higher standard of living) and increases farmers’ ability to cope with challenges, mainly through knowledge transfer, access to capital and capacity building on a local level. Although positive effects on female farmers were identified, cultural preconditions (e.g., polygamy) harm efforts to strengthen women to a higher degree and gender disparities are still challenging. Further social problems (i.e., high birth rates, a poor education system and a lack of health care), global trading schemes as well as environmental factors (i.e., water scarcity and extreme weather events) cannot be fully offset by the conversion to organic cotton cultivation. Farmers in the Meatu region profit to a high degree from organic agriculture, mainly due to access to knowledge and extension services, nevertheless important challenges remain for farmers and their families.
Caspase-dependent cell death-associated release of nucleosome and damage-associated molecular patterns
Authors: Yoon S , Park S J , Han J H , Kang J H , Kim J-h , Lee J , Park S , Shin H-J , Kim K , Yun M , Chwae Y-J
Published: October 2014

Apoptosis, which is anti-inflammatory, and necrosis, which is pro-inflammatory, represent the extremes of the cell death spectrum. Cell death is complex and both apoptosis and necrosis can be observed in the same cells or tissues. Here, we introduce a novel combined mode of cellular demise – caspase-dependent regulated necrosis. Most importantly, it is mainly characterized with release of marked amount of oligo- or poly-nucleosomes and their attached damage-associated molecular patterns (DAMPs) and initiated by caspase activation. Caspase-activated DNase has dual roles in nucleosomal release as it can degrade extracellularly released chromatin into poly- or oligo-nucleosomes although it prohibits release of nucleosomes. In addition, osmotically triggered water movement following Cl− influx and subsequent Na+ influx appears to be the major driving force for nucleosomal and DAMPs release. Finally, Ca2+-activated cysteine protease, calpain, is an another essential factor in nucleosomal and DAMPs release because of complete reversion to apoptotic morphology from necrotic one and blockade of nucleosomal and DAMPs release by its inhibition.
NLRP3 inflammasome activation by mitochondrial ROS in bronchial epithelial cells is required for allergic inflammation
Authors: Kim S R , Kim D I , Kim S H , Lee H , Lee K S , Cho S H , Lee Y C
Published: October 2014

Abnormality in mitochondria has been suggested to be associated with development of allergic airway disorders. In this study, to evaluate the relationship between mitochondrial reactive oxygen species (ROS) and NLRP3 inflammasome activation in allergic asthma, we used a newly developed mitochondrial ROS inhibitor, NecroX-5. NecroX-5 reduced the increase of mitochondrial ROS generation in airway inflammatory cells, as well as bronchial epithelial cells, NLRP3 inflammasome activation, the nuclear translocation of nuclear factor-κB, increased expression of various inflammatory mediators and pathophysiological features of allergic asthma in mice. Finally, blockade of IL-1β substantially reduced airway inflammation and hyperresponsiveness in the asthmatic mice. These findings suggest that mitochondrial ROS have a critical role in the pathogenesis of allergic airway inflammation through the modulation of NLRP3 inflammasome activation, providing a novel role of airway epithelial cells expressing NLRP3 inflammasome as an immune responder.
Structural basis of IL-23 antagonism by an Alphabody protein scaffold
Authors: Desmet Johan , Verstraete Kenneth , Bloch Yehudi , Lorent Eric , Wen Yurong , Devreese Bart , Vandenbroucke Karen , Loverix Stefan , Hettmann Thore , Deroo Sabrina , Somers Klaartje , Henderikx Paula , Lasters Ignace , Savvides Savvas N.
Published: October 2014

Protein scaffolds can provide a promising alternative to antibodies for various biomedical and biotechnological applications, including therapeutics. Here we describe the design and development of the Alphabody, a protein scaffold featuring a single-chain antiparallel triple-helix coiled-coil fold. We report affinity-matured Alphabodies with favourable physicochemical properties that can specifically neutralize human interleukin (IL)-23, a pivotal therapeutic target in autoimmune inflammatory diseases such as psoriasis and multiple sclerosis. The crystal structure of human IL-23 in complex with an affinity-matured Alphabody reveals how the variable interhelical groove of the scaffold uniquely targets a large epitope on the p19 subunit of IL-23 to harness fully the hydrophobic and hydrogen-bonding potential of tryptophan and tyrosine residues contributed by p19 and the Alphabody, respectively. Thus, Alphabodies are suitable for targeting protein–protein interfaces of therapeutic importance and can be tailored to interrogate desired design and binding-mode principles via efficient selection and affinity-maturation strategies.
A liquid azobenzene derivative as a solvent-free solar thermal fuel
Authors: Masutani Kouta , Morikawa Masa-aki , Kimizuka Nobuo
Published: October 2014

A liquid trans-azobenzene derivative facilely isomerizes to the higher energy cis-isomer, allowing high volumetric density storage of the photon energy.
A rare (3,4,5)-connected metal–organic framework featuring an unprecedented 1D + 2D → 3D self-interpenetrated array and an O-atom lined pore surface: structure and controlled drug release
Authors: Zhong Di-Chang , Liao Lie-Qiang , Deng Ji-Hua , Chen Qing , Lian Ping , Luo Xu-Zhong
Published: October 2014

A rare (3,4,5)-connected metal–organic framework has been constructed, which features an unprecedented 1D + 2D → 3D self-interpenetrated array and an O-atom lined pore surface, and shows good controlled release of ibuprofen.
CW-laser-induced morphological changes of a single gold nanoparticle on glass: observation of surface evaporation
Authors: Setoura Kenji , Okada Yudai , Hashimoto Shuichi
Published: October 2014

CW laser illumination of a single gold nanoparticle enables surface evaporation resulting in controlled size-reduction that depends on laser intensity.
Nitrate behaviors and source apportionment in an aquatic system from a watershed with intensive agricultural activities
Authors: Lu Lu , Cheng Hongguang , Pu Xiao , Liu Xuelian , Cheng Qianding
Published: October 2014

Nitrate pollution in aquatic systems caused by intensive agricultural activities is a serious problem in the Sanjiang Plain.
Labelling of N-hydroxysuccinimide-modified rhodamine B on cellulose nanofibrils by the amidation reaction
Authors: Navarro Julien R. G. , Bergström Lennart
Published: October 2014

Luminescent cellulose nanofibrils (CNF) have been produced by graftingN-hydroxysuccinimide(NHS)-modified rhodamine onto an amine-modified CNF.
Liposomes containing mannose-6-phosphate-cholesteryl conjugates for lysosome-specific delivery
Authors: Crucianelli E. , Bruni P. , Frontini A. , Massaccesi L. , Pisani M. , Smorlesi A. , Mobbili G.
Published: October 2014

We present a novel liposomal nanocarrier containing mannose 6-phosphate-cholesteryl conjugates and show its ability to reach the lysosomes by means of confocal and fluorescence microscopy measurements.
Design and synthesis of pyrrole–5-(2,6-dichlorobenzyl)sulfonylindolin-2-ones with C-3′ side chains as potent Met kinase inhibitors
Authors: Liu Chia-Wei , Lai Chun-Liang , Lin Yu-Hsiang , Teng Li-Wei , Yang Sheng-chuan , Wei Win-Yin , Lin Shu Fu , Yang Ju-Ying , Huang Hung-Jyun , Wang Ru-Wen , Chiang Chao-Cheng , Lee Mei-Hui , Wang Yu-Chuan , Chuang Shih-Hsien , Chang Jia-Ming , Lee Ying-Shuan E. , Huang Jiann-Jyh
Published: October 2014

Subnanomolar Met inhibitors.
Silicone–barium titanate composites with increased electromechanical sensitivity. The effects of the filler morphology
Authors: Bele A. , Cazacu M. , Stiubianu G. , Vlad S.
Published: October 2014

Dielectric elastomers were prepared on the basis of high molecular weight polydimethylsiloxane-α,ω-diol filled with barium titanate particles having well-defined size and morphology.
Binding and removal of octahedral, tetrahedral, square planar and linear anions in water by means of activated carbon functionalized with a pyrimidine-based anion receptor
Authors: Savastano Matteo , Arranz-Mascarós Paloma , Bazzicalupi Carla , Bianchi Antonio , Giorgi Claudia , Godino-Salido M. Luz , Gutiérrez-Valero Maria Dolores , López-Garzón Rafael
Published: October 2014

Enhanced anion recovery from water is achieved upon functionalization of activated carbon with polyamine groups.
Merging of the photocatalysis and copper catalysis in metal–organic frameworks for oxidative C–C bond formation
Authors: Shi Dongying , He Cheng , Qi Bo , Chen Cong , Niu Jingyang , Duan Chunying
Published: October 2014

A new approach to merge Cu-catalysis/Ru-photocatalysis within one single MOF was achieved by incorporating [SiW11O39Ru(H2O)]5− into Cu–BPY MOFs.
A highly durable silica/polyimide superhydrophobic nanocomposite film with excellent thermal stability and abrasion-resistant performance
Authors: Gong Guangming , Gao Kai , Wu Juntao , Sun Na , Zhou Chen , Zhao Yong , Jiang Lei
Published: October 2014

Superhydrophobic silica/PI nanocomposite film with comprehensive dependent high performances is easily electrospun.
Promising thermoelectric performance in n-type AgBiSe2: effect of aliovalent anion doping
Authors: Guin Satya N. , Srihari Velaga , Biswas Kanishka
Published: October 2014

Halide ion (Cl−/Br−/I−) aliovalently dopes on the Se2−sublattice and contributes one n-type carrier in AgBiSe2, which gives rise to improved electronic transport properties. A peakZT, value of ∼0.9 at ∼810 K has been achieved for the AgBiSe1.98Cl0.02sample, which makes it a promising n-type thermoelectric material for mid-temperature applications.
Computational study of collisions between O(3P) and NO(2Π) at temperatures relevant to the hypersonic flight regime
Authors: Castro-Palacio Juan Carlos , Nagy Tibor , Bemish Raymond J. , Meuwly Markus
Published: October 2014

Reactions involving N and O atoms dominate the energetics of the reactive air flow around spacecraft when reentering the atmosphere in the hypersonic flight regime. For this reason, the thermal rate coefficients for reactive processes involving O(3P) and NO(2Π) are relevant over a wide range of temperatures. For this purpose, a potential energy surface (PES) for the ground state of the NO2 molecule is constructed based on high-level ab initio calculations. These ab initio energies are represented using the reproducible kernel Hilbert space method and Legendre polynomials. The global PES of NO2 in the ground state is constructed by smoothly connecting the surfaces of the grids of various channels around the equilibrium NO2 geometry by a distance-dependent weighting function. The rate coefficients were calculated using Monte Carlo integration. The results indicate that at high temperatures only the lowest A-symmetry PES is relevant. At the highest temperatures investigated (20 000 K), the rate coefficient for the “O1O2+N” channel becomes comparable (to within a factor of around three) to the rate coefficient of the oxygen exchange reaction. A state resolved analysis shows that the smaller the vibrational quantum number of NO in the reactants, the higher the relative translational energy required to open it and conversely with higher vibrational quantum number, less translational energy is required. This is in accordance with Polanyi's rules. However, the oxygen exchange channel (NO2+O1) is accessible at any collision energy. Finally, this work introduces an efficient computational protocol for the investigation of three-atom collisions in general.
Complex absorbing potential based Lorentzian fitting scheme and time dependent quantum transport
Authors: Xie Hang , Kwok Yanho , Jiang Feng , Zheng Xiao , Chen GuanHua
Published: October 2014

Based on the complex absorbing potential (CAP) method, a Lorentzian expansion scheme is developed to express the self-energy. The CAP-based Lorentzian expansion of self-energy is employed to solve efficiently the Liouville-von Neumann equation of one-electron density matrix. The resulting method is applicable for both tight-binding and first-principles models and is used to simulate the transient currents through graphene nanoribbons and a benzene molecule sandwiched between two carbon-atom chains.
Generalized extended Lagrangian Born-Oppenheimer molecular dynamics
Authors: Niklasson Anders M. N. , Cawkwell Marc J.
Published: October 2014

Extended Lagrangian Born-Oppenheimer molecular dynamics based on Kohn-Sham density functional theory is generalized in the limit of vanishing self-consistent field optimization prior to the force evaluations. The equations of motion are derived directly from the extended Lagrangian under the condition of an adiabatic separation between the nuclear and the electronic degrees of freedom. We show how this separation is automatically fulfilled and system independent. The generalized equations of motion require only one diagonalization per time step and are applicable to a broader range of materials with improved accuracy and stability compared to previous formulations.
Discrimination of nuclear spin isomers exploiting the excited state dynamics of a quinodimethane derivative
Authors: Obaid Rana , Kinzel Daniel , Oppel Markus , González Leticia
Published: October 2014

Despite the concept of nuclear spin isomers (NSIs) exists since the early days of quantum mechanics, only few approaches have been suggested to separate different NSIs. Here, a method is proposed to discriminate different NSIs of a quinodimethane derivative using its electronic excited state dynamics. After electronic excitation by a laser field with femtosecond time duration, a difference in the behavior of several quantum mechanical operators can be observed. A pump-probe experimental approach for separating these different NSIs is then proposed.
Quantum reactive scattering of O(3P)+H2 at collision energies up to 4.4 eV
Authors: Gacesa Marko , Kharchenko Vasili
Published: October 2014

We report the results of quantum scattering calculations for the O(3P)+H2 reaction for a range of collision energies from 0.4 to 4.4 eV, important for astrophysical and atmospheric processes. The total and state-to-state reactive cross sections are calculated using a fully quantum time-independent coupled-channel approach on recent potential energy surfaces of 3A′ and 3A″ symmetry. A larger basis set than in the previous studies was used to ensure single-surface convergence at higher energies. Our results agree well with the published data at lower energies and indicate the breakdown of reduced dimensionality approach at collision energies higher than 1.5 eV. Differential cross sections and momentum transfer cross sections are also reported.
Development of a Kingdon ion trap system for trapping externally injected highly charged ions
Authors: Numadate Naoki , Okada Kunihiro , Nakamura Nobuyuki , Tanuma Hajime
Published: October 2014

We have developed a Kingdon ion trap system for the purpose of the laboratory observation of the x-ray forbidden transitions of highly charged ions (HCIs). Externally injected Arq+ (q = 5−7) with kinetic energies of 6q keV were successfully trapped in the ion trap. The energy distribution of trapped ions is discussed in detail on the basis of numerical simulations. The combination of the Kingdon ion trap and the time-of-flight mass spectrometer enabled us to measure precise trapping lifetimes of HCIs. As a performance test of the instrument, we measured trapping lifetimes of Arq+ (q = 5−7) under a constant number density of H2 and determined the charge-transfer cross sections of Arq+(q = 5, 6)-H2 collision systems at binary collision energies of a few eV. It was confirmed that the present cross section data are consistent with previous data and the values estimated by some scaling formula.
Influence of curvature on the device physics of thin film transistors on flexible substrates
Authors: Amalraj Rex , Sambandan Sanjiv
Published: October 2014

Thin film transistors (TFTs) on elastomers promise flexible electronics with stretching and bending. Recently, there have been several experimental studies reporting the behavior of TFTs under bending and buckling. In the presence of stress, the insulator capacitance is influenced due to two reasons. The first is the variation in insulator thickness depending on the Poisson ratio and strain. The second is the geometric influence of the curvature of the insulator-semiconductor interface during bending or buckling. This paper models the role of curvature on TFT performance and brings to light an elegant result wherein the TFT characteristics is dependent on the area under the capacitance-distance curve. The paper compares models with simulations and explains several experimental findings reported in literature.
Nanoscale structural heterogeneity in Ni-rich half-Heusler TiNiSn
Authors: Douglas Jason E. , Chater Philip A. , Brown Craig M. , Pollock Tresa M. , Seshadri Ram
Published: October 2014

The structural implications of excess Ni in the TiNiSn half-Heusler compound are examined through a combination of synchrotron x-ray and neutron scattering studies, in conjunction with first principles density functional theory calculations on supercells. Despite the phase diagram suggesting that TiNiSn is a line compound with no solid solution, for small x in TiNi1+xSn there is indeed an appearance—from careful analysis of the scattering—of some solubility, with the excess Ni occupying the interstitial tetrahedral site in the half-Heusler structure. The analysis performed here would point to the excess Ni not being statistically distributed, but rather occurring as coherent nanoclusters. First principles calculations of energetics, carried out using supercells, support a scenario of Ni interstitials clustering, rather than a statistical distribution.
The stochastic dynamics of tethered microcantilevers in a viscous fluid
Authors: Robbins Brian A. , Radiom Milad , Ducker William A. , Walz John Y. , Paul Mark R.
Published: October 2014

We explore and quantify the coupled dynamics of a pair of micron scale cantilevers immersed in a viscous fluid that are also directly tethered to one another at their tips by a spring force. The spring force, for example, could represent the molecular stiffness or elasticity of a biomolecule or material tethered between the cantilevers. We use deterministic numerical simulations with the fluctuation-dissipation theorem to compute the stochastic dynamics of the cantilever pair for the conditions of experiment when driven only by Brownian motion. We validate our approach by comparing directly with experimental measurements in the absence of the tether which shows excellent agreement. Using numerical simulations, we quantify the correlated dynamics of the cantilever pair over a range of tether stiffness. Our results quantify the sensitivity of the auto- and cross-correlations of equilibrium fluctuations in cantilever displacement to the stiffness of the tether. We show that the tether affects the magnitude of the correlations which can be used in a measurement to probe the properties of an attached tethering substance. For the configurations of current interest using micron scale cantilevers in water, we show that the magnitude of the fluid coupling between the cantilevers is sufficiently small such that the influence of the tether can be significant. Our results show that the cross-correlation is more sensitive to tether stiffness than the auto-correlation indicating that a two-cantilever measurement has improved sensitivity when compared with a measurement using a single cantilever.
Using multi-walled carbon nanotubes in spark plasma sintered Pb(Zr0.47Ti0.53)O3 ceramics for tailoring dielectric and tunability properties
Authors: Ciomaga Cristina E. , Padurariu Leontin , Curecheriu Lavinia P. , Lupu Nicoleta , Lisiecki Isabelle , Deluca Marco , Tascu Sorin , Galassi Carmen , Mitoseriu Liliana
Published: October 2014

The addition of small amounts (below 0.1 wt. %) of multi-walled carbon nanotubes (MWCNTs) to Pb(Zr0.47Ti0.53)O3 (PZT) ceramics prepared by spark plasma sintering is proposed as a method of tailoring the electrical properties, which are expected to be modified with respect to the pure PZT, both as result of the presence of 1-D conductive fillers in the ceramic product and via the microstructural modifications of ceramics induced during the sintering. The addition of even small amounts of carbon nanotubes strongly reduced the sinterability of PZT ceramics and resulted in the porous and fine-grained microstructures (relative density of 73% for a MWCNT addition of 0.5 vol. % by comparison with 91% in the pure PZT, produced in the same conditions). A monotonous decrease of permittivity with increasing the MWCNT level from ∼830 in pure PZT to ∼627 for x = 0.5 vol. %, at a fixed frequency f = 1kHz, and low dielectric losses below 2% have been observed. Tunability increases with respect to the values of dense PZT for small concentration of MWCNT as high as 0.0625 vol. % and then monotonically decreases for higher additions. Calculations by finite element modeling demonstrated that by addition of 1-D conductive fillers with compositions below the percolation limits to porous microstructures, the major role in changing the electrical properties via local field modification is related to the induced porosity rather than to the influence of the small amounts of MWCNTs survived after sintering and post-annealing treatment. The reduced permittivity with about 14% combined with low losses and higher tunability than in the pure PZT ceramics obtained at reasonable fields, makes the idea of using the addition of MWCNTs to ferroelectric ceramics an interesting approach in searching new structures for tunability properties.
Hyperbolic-metamaterial antennas for broadband enhancement of dipole emission to free space
Authors: Valagiannopoulos C. A. , Mirmoosa M. S. , Nefedov I. S. , Tretyakov S. A. , Simovski C. R.
Published: October 2014

Dipole emitters used in nano optics and nanophotonics (e.g., fluorescent molecules or quantum dots) are weak radiators and thus detecting the radiation of a single emitter gets possible only if it is significantly enhanced. For this enhancement, one often utilizes resonant nanoantennas (Purcell's effect); this method, however, requires the exact knowledge of source location and radiation frequency which constitute a significant drawback. One known possibility for broadband location-insensitive radiation enhancement is to use a layer of the so-called hyperbolic metamaterial. However, the enhanced radiated energy is mainly directed into the volume of the lossy medium, where it is lost to heating. In this work, we suggest specific shapes of macroscopic hyperbolic metamaterial samples to open radiation windows for enhanced radiation to free space. We show that hyperbolic media slabs with properly shaped macroscopic grooves convert the evanescent waves produced by a dipole into waves traveling in free space, which results in the enhancement of useful radiation by one to two orders of magnitude. That level of enhancement of radiation into free-space which is also wideband and of non-resonant nature has not been reported up to now. These results may open possibilities for realization of broadband and directive antennas, where the primary radiators are randomly positioned fluorescent molecules or quantum dots.
Simultaneous triple 914 nm, 1084 nm, and 1086 nm operation of a diode-pumped Nd:YVO4 laser
Authors: Lü Yanfei , Xia Jing , Liu Huilong , Pu Xiaoyun
Published: October 2014

We report a diode-pumped continuous-wave (cw) triple-wavelength Nd:YVO4 laser operating at 914, 1084, and 1086 nm. A theoretical analysis has been introduced to determine the threshold conditions for simultaneous triple-wavelength laser. Using a T-shaped cavity, we realized an efficient triple-wavelength operation at 4F3/2→4I9/2 and 4F3/2→4I11/2 transitions for Nd:YVO4 crystal, simultaneously. At an absorbed pump power of 16 W (or 25 W of incident pump power), the maximum output power was 2.3 W, which included 914 nm, 1084 nm, and 1086 nm three wavelengths, and the optical conversion efficiency with respect to the absorbed pump power was 14.4%.
Probing plasmonic breathing modes optically
Authors: Krug Markus K. , Reisecker Michael , Hohenau Andreas , Ditlbacher Harald , Trügler Andreas , Hohenester Ulrich , Krenn Joachim R.
Published: October 2014

The confinement of surface plasmon modes in flat nanoparticles gives rise to plasmonic breathing modes. With a vanishing net dipole moment, breathing modes do not radiate, i.e., they are optically dark. Having thus escaped optical detection, breathing modes were only recently revealed in silver nanodisks with electron energy loss spectroscopy in an electron microscope. We show that for disk diameters >200 nm, retardation induced by oblique optical illumination relaxes the optically dark character. This makes breathing modes and thus the full plasmonic mode spectrum accessible to optical spectroscopy. The experimental spectroscopy data are in excellent agreement with numerical simulations.
Biomanufacturing and self-propulsion dynamics of nanoscale bacteria-enabled autonomous delivery systems
Authors: Traore Mahama A. , Damico Carmen M. , Behkam Bahareh
Published: October 2014

Flagellated bacteria have superb self-propulsion capabilities and are able to effectively move through highly viscous fluid and semi-solid (porous) environments. This innate aptitude has been harvested for whole-cell actuation of bio-hybrid microrobotic systems with applications in directed transport and microassembly. In this work, we present the biomanufacturing of Nanoscale Bacteria-Enabled Autonomous Delivery Systems (NanoBEADS) by controlled self-assembly and investigate the role of nanoparticle load on the dynamics of their self-propulsion in aqueous environments. Each NanoBEADS agent is comprised of spherical polystyrene nanoparticles assembled onto the body of a flagellated Escherichia coli bacterium. We demonstrate that the NanoBEADS assembly configuration is strongly dependent upon the nanoparticles to bacteria ratio. Furthermore, we characterized the stochastic motion of the NanoBEADS as a function of the quantity and size of the nanoparticle load and computationally analyzed the effect of the nanoparticle load on the experienced drag force. We report that the average NanoBEADS swimming speed is reduced to 65% of the free-swimming bacteria speed (31 μm/s) at the highest possible load. NanoBEADS can be utilized as single agents or in a collaborative swarm in order to carry out specific tasks in a wide range of applications ranging from drug delivery to whole cell biosensing.
Thickness and growth-condition dependence of in-situ mobility and carrier density of epitaxial thin-film Bi2Se3
Authors: Hellerstedt Jack , Edmonds Mark T. , Chen J. H. , Cullen William G. , Zheng C. X. , Fuhrer Michael S.
Published: October 2014

Bismuth selenide Bi2Se3 was grown by molecular beam epitaxy, while carrier density and mobility were measured directly in situ as a function of film thickness. Carrier density shows high interface n-doping (1.5 × 1013 cm−2) at the onset of film conduction and bulk dopant density of ∼5 × 1011 cm−2 per quintuple-layer unit, roughly independent of growth temperature profile. Mobility depends more strongly on the growth temperature and is related to the crystalline quality of the samples quantified by ex-situ atomic force microscopy measurements. These results indicate that Bi2Se3 as prepared by widely employed parameters is n-doped before exposure to atmosphere, the doping is largely interfacial in origin, and dopants are not the limiting disorder in present Bi2Se3 films.
Impacts of SiN passivation on the degradation modes of AlGaN/GaN high electron mobility transistors under reverse-bias stress
Authors: Chen Wei-Wei , Ma Xiao-Hua , Hou Bin , Zhu Jie-Jie , Chen Yong-He , Zheng Xue-Feng , Zhang Jin-Cheng , Hao Yue
Published: October 2014

Impacts of SiN passivation on the degradation modes of AlGaN/GaN high electron mobility transistors are investigated. The gate leakage current decreases significantly upon removing the SiN layer and no clear critical voltage for the sudden degradation of the gate leakage current can be observed in the reverse-bias step-stress experiments. Gate-lag measurements reveal the decrease of the fast-state surface traps and the increase of slow-state traps after the passivation layer removal. It is postulated that consistent surface charging relieves the electric field peak on the gate edge, thus the inverse piezoelectric effect is shielded.
Comprehensive kinetic analysis of the plasma-wall transition layer in a strongly tilted magnetic field
Authors: Tskhakaya D. D. , Kos L.
Published: October 2014

The magnetized plasma-wall transition (MPWT) layer at the presence of the obliquity of the magnetic field to the wall consists of three sub-layers: the Debye sheath (DS), the magnetic pre-sheath (MPS), and the collisional pre-sheath (CPS) with characteristic lengths λD (electron Debye length), ρi (ion gyro-radius), and ℓ (the smallest relevant collision length), respectively. Tokamak plasmas are usually assumed to have the ordering λD≪ρi≪ℓ, when the above-mentioned sub-layers can be distinctly distinguished. In the limits of εDm(λD/ρi)→0 and εmc(ρi/ℓ)→0 (“asymptotic three-scale (A3S) limits”), these sub-layers are precisely defined. Using the smallness of the tilting angle of the magnetic field to the wall, the ion distribution functions are found for three sub-regions in the analytic form. The equations and characteristic length-scales governing the transition (intermediate) regions between the neighboring sub-layers (CPS – MPS and MPS – DS) are derived, allowing to avoid the singularities arising from the εDm→0 and εmc→0 approximations. The MPS entrance and the related kinetic form of the Bohm–Chodura condition are successfully defined for the first time. At the DS entrance, the Bohm condition maintains its usual form. The results encourage further study and understanding of physics of the MPWT layers in the modern plasma facilities.
Meander-shaped magnetoimpedance sensor for measuring inhomogeneous magnetic fringe fields of NiFe films
Authors: Wang Tao , Lei Chong , Yang Zhen , Sun Xuecheng , Liu Yan , Zhou Yong
Published: October 2014

Magnetic fringe fields of NiFe films were measured by giant magnetoimpedance (GMI) sensor, in this work. We have observed an interesting GMI phenomenon: the impedance enhanced first and then declined due to the presence of NiFe films, it is suggested that magnetic fringe fields have strengthened the longitudinal external magnetic field. Results indicated that the GMI sensor was able to quantify the magnetized NiFe films from 1 × 5 to 5 × 5 mm2. Anyway, this study has extended the application of GMI sensor to film detection, which makes it promising in detecting the defects of soft magnetic devices.
Hysteresis during field emission from chemical vapor deposition synthesized carbon nanotube fibers
Authors: Cahay M. , Murray P. T. , Back T. C. , Fairchild S. , Boeckl J. , Bulmer J. , Koziol K. K. K. , Gruen G. , Sparkes M. , Orozco F. , O'Neill W.
Published: October 2014

Hysteresis in the field emission (FE) data of a chemical vapor synthesized carbon nanotube fiber cathode is analyzed in the regime where self-heating effects are negligible. In both the forward and reverse applied field sweeps, various FE modes of operation are identified: including Fowler-Nordheim (FN) tunneling and space-charge limited emission from the fiber tip and FN emission from the fiber sidewall. Hysteresis in the FE data is linked to the difference in the field enhancement factors in the different FE modes of operation in the forward and reverse sweeps and related to changes in the fiber morphology.