bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced electrochemical properties of a novel polyvinyl formal membrane supporting gel polymer electrolyte by Al2O3 modification
Authors: Wen Yan , Lian Fang , Ren Yan , Guan Hong‐Yan
Published: February 2014

Polyvinyl formal (PVFM)‐based dense polymer membranes with nano‐Al2O3 doping are prepared via phase inversion method. The membranes and also their performances as gel polymer electrolytes (GPEs) for lithium ion battery are studied by field emission scanning electron microscope, X‐ray diffraction, differential scanning calorimetry, mechanical strength test, electrolyte uptake test, electrochemical impedance spectroscopy, cyclic voltammetry, and charge–discharge test. The polymer membrane with 3 wt % nano‐Al2O3 doping shows the improved mechanical strength of 12.16 MPa and electrolyte uptake of 431.25% compared with 10.47 MPa and 310.59% of the undoped sample, respectively. The membrane absorbs and swells liquid electrolyte to form stable GPE with ionic conductivity of 4.92 × 10−4 S cm−1 at room temperature, which is higher than 1.77 × 10−4 S cm−1 of GPE from the undoped membrane. Moreover, the Al2O3‐modified membrane supporting GPE exhibits wide electrochemical stability window of 1.2–4.8 V (vs. Li/Li+) and good compatibility with LiFePO4 electrode, which implies Al2O3‐modified PVFM‐based GPE to be a promising candidate for lithium ion batteries. © 2014 Wiley Periodicals, Inc. J. Polym. Sci. Part B: Polym. Phys. 2014, 52, 572–577
Spin mode locking in quantum dots revisited
Authors: Varwig S. , Greilich A. , Yakovlev D. R. , Bayer M.
Published: February 2014

A comprehensive overview of coherent spin manipulation in (In,Ga)As quantum dots, singly charged with resident electrons or holes, is given, from orientation to rotation of the spins. These operations are performed by excitation of the charged exciton complex with laser pulses. The specifics of the approach is performing the manipulations on dot ensembles, potentially giving robustness to the coherent spin dynamics. In particular, we focus on the spin mode‐locking regime, in which the precession of the spins about an external magnetic field is synchronized with the periodic pulsed laser excitation initiating the operations. The periodic excitation protocol introduces a frequency comb through which detrimental effects of the inhomogeneities in the spin system can be avoided.
Lift‐out procedures for atom probe tomography targeting nanoscale features in core‐shell nanowire heterostructures
Authors: Padalkar Sonal , Riley James R. , Li Qiming , Wang George T. , Lauhon Lincoln J.
Published: February 2014

Focused ion beam (FIB) milling and lift‐out was used to prepare atom probe tomography (APT) specimens from GaN‐InGaN multi‐quantum well (MQW) nanowire arrays. Modifications to the conventional FIB lift‐out technique enable the site‐specific analysis of different regions of a single nanowire heterostructure. Three dimensional (3‐D) reconstructions of quantum wells generated by analysis along different directions with respect to the heterointerface demonstrate both the capabilities and limitations of atom probe tomographic analysis. The methods described herein can be applied to the site‐specific analysis of other complex 3‐D heterostructures. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High temperature HVPE of AlN on sapphire templates
Authors: Baker Troy , Mayo Ashley , Veisi Zeinab , Lu Peng , Schmitt Jason
Published: February 2014

Aluminum nitride (AlN) was grown on c‐plane sapphire substrates by hydride vapor phase epitaxy (HVPE). The experiments utilized a two zone inductively heated hot‐wall reactor capable of temperatures exceeding 1500 °C. The precursors of aluminum monochloride (AlCl) and aluminum trichloride (AlCl3) were used, and it was determined that AlCl3 was more thermodynamically conducive to single crystalline AlN growth at 1450 °C. AlN templates were optimized at a thickness of 1 µm without cracking. The double axis X‐ray diffraction (XRD) rocking curves full width half maximums (FWHMs) were reproducibly demonstrated with an average of 130 arcsec for the (002) and 516 arcsec for the (102). The AlN was transparent in the UV spectrum with a band gap cut off of 200 nm. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Akt Signaling Leads to Stem Cell Activation and Promotes Tumor Development in Epidermis
Authors: Segrelles Carmen , García-Escudero Ramón , Garín Maria I. , Aranda Juan F. , Hernández Pilar , Ariza José M. , Santos Mirentxu , Paramio Jesús M. , Lorz Corina
Published: February 2014

Hair follicle stem cells (HF-SCs) alternate between periods of quiescence and proliferation, to finally differentiate into all the cell types that constitute the hair follicle. Also, they have been recently identified as cells of origin in skin cancer. HF-SCs localize in a precise region of the hair follicle, the bulge, and molecular markers for this population have been established. Thus, HF-SCs are good model to study the potential role of oncogenic activations on SC physiology. Expression of a permanently active form of Akt (myrAkt) in basal cells leads to Akt hyperactivation specifically in the CD34+Itga6H population. This activation causes bulge stem cells to exit from quiescence increasing their response to proliferative stimuli and affecting some functions such as cell migration. HF-SC identity upon Akt activation is preserved; in this sense, increased proliferation does not result in stem cell exhaustion with age suggesting that Akt activation does not affect self-renewal an important aspect for normal tissue maintenance and cancer development. Genome-wide transcriptome analysis of HF-SC isolated from myrAkt and wild-type epidermis underscores changes in metabolic pathways characteristic of cancer cells. These differences manifest during a two-step carcinogenesis protocol in which Akt activation in HF-SCs results in increased tumor development and malignant transformation. Stem Cells  2014;32:1917–1928
Eroticism as Embodied Emotion: The Erotics of Renaissance Faire
Authors: Newmahr Staci
Published: February 2014

This paper conceptualizes eroticism as emotional experience. I use the Renaissance Faire to illustrate the construction of asexual eroticism along three dimensions: the carnal experience of Faire, its focus on physicality, and intimations of increased interpersonal access. This approach forefronts the complexity of eroticism and situates the erotic squarely in the sociology of emotion, providing a model for understanding a range of emotional, embodied, and nonsexual charges as erotic. More broadly, the analysis seeks to contribute to the study of all emotion as embodied.
Clarifying the complexities of school–museum interactions: Perspectives from two communities
Authors: Kisiel James F.
Published: February 2014

If we truly wish to promote science or STEM education, then it would seem that the joining of resources and expertise from the communities of formal schooling and informal science education institutions or ISEIs (museums, aquariums, and the like) would be an important early step. Yet creating such connections between teacher and museum remain a challenge for both teachers and informal educators. This study employs a communities of practice lens (Wenger, 1998) to provide a deeper explanation for the challenges inherent in those programs and experiences (field trips, outreach programs, teacher professional development) where schools and informal science institutions interact to create unique learning opportunities. To better understand the expectations and perceived challenges of these boundary activities, questionnaires, focus groups and interviews were used to gather information from over 200 teachers and informal science institution staff in southern California. Several factors, identified by both groups, were found to influence these shared experiences, including issues of authority, capacity, communication, and complexity. By considering both educators' perspectives, we gain a clearer understanding of the practice of these communities and how such practices influence the activities at these boundaries. Furthermore, a closer look at avid users—those teachers who do successfully and regularly make use of ISEIs—reveals possible avenues for strengthening such boundary activities and potentially creating a more effective merging of learning and teaching resources. © 2014 Wiley Periodicals, Inc. J Res Sci Teach 51: 342–367, 2014
Effects of UV weathering on the mechanical and antibacterial performance of peroxide‐cured silicone rubber containing biocide HPQM
Authors: Taptim Kulnida , Sombatsompop Narongrit
Published: February 2014

2‐Hydroxypropyl‐3‐piperazinyl‐quinoline carboxylic acid methacrylate (HPQM) was used as a biocide in a silicone rubber compound. Antibacterial and mechanical performance of the compound was assessed before and after exposure to UV light for different times. Drop‐plate and halo tests were employed to evaluate qualitatively and quantitatively the antibacterial performance of the compound against Escherichia coli (E. coli, ATCC 25922) and Staphylococcus aureus (S. aureus, ATCC 25923). The results showed that the cure characteristics and the physical and mechanical properties of the HPQM‐containing rubber compound were strongly affected by the UV light. The tensile properties and hardness increased with UV aging. The lightness (L*) of the rubber compound without HPQM did not change with UV exposure, whereas that for the compound with HPQM decreased with UV exposure. The longer the contact time, the better the ability for killing the bacteria. After experiencing initial UV aging for 3 days, the rubber compound with HPQM showed an effective killing ability. However, after prolonged UV exposure, the antibacterial efficacy was reduced as a result of HPQM removal from the rubber surface during the condensation stage and a post‐curing reaction of the residual peroxide in the rubber compound. Under UV light, the silicone rubber compound with HPQM had a greater preference for killing the E. coli. J. VINYL ADDIT. TECHNOL., 20:49–56, 2014. © 2014 Society of Plastics Engineers
Utilization of machine‐learning algorithms for wind turbine site suitability modeling in Iowa, USA
Authors: Petrov Andrey N. , Wessling Jordan M.
Published: February 2014

Because of the current shift away from fossil fuels and toward renewable energy sources, it is necessary to plan for the installation of new infrastructure to meet the demand for clean energy. Traditional methods for determining wind turbine site suitability suffer from the selection of arbitrary criteria and model parameters by experts, which may lead to a degree of uncertainty in the models produced. An alternative empirically based methodology for building a wind turbine siting model for the state of Iowa is presented in the study. We employ ‘ecological niche’ principles traditionally utilized to model species allocation to develop a new multicriteria, spatially explicit framework for wind turbine placement. Using information on suitability conditions at existing turbine locations, we incorporate seven variables (wind speed, elevation, slope, land cover, distance of infrastructure and settlements, and population density) into two machine‐learning algorithms [maximum entropy method (Maxent) and Genetic Algorithm for Rule Set Prediction (GARP)] to model suitable areas for installation of wind turbines. The performance of this method is tested at the statewide level and a six‐county region in western Iowa. Maxent and GARP identified areas in the Northwest and North Central regions of Iowa as the optimum location for new wind turbines. Information on variable contributions from Maxent illuminates the relative importance of environmental variables and its scale‐dependent nature. It also allows validating existing assumptions about the relationship between variables and wind turbine suitability. The resultant models demonstrate high levels of accuracy and suggest that the presented approach is a possible methodology for developing wind turbine siting applications. Copyright © 2014 John Wiley & Sons, Ltd.
Ethnic Disparities in Trauma Mortality Outcomes
Authors: Leow Jeffrey J. , Lim Vanessa W. , Lingam Pravin , Go Karen T. S. , Teo Li Tserng
Published: February 2014

Background

Ethnic disparities in trauma mortality outcomes have been demonstrated in the United States according to the US National Trauma Data Bank. The aim of this study was to determine the effect of race/ethnicity on trauma mortality in Singapore.

Methods

This was a retrospective review of patients aged 18–64 years with an injury severity score (ISS) ≥9 in the Trauma Registry of Tan Tock Seng Hospital, a 1,300‐bed trauma center in Singapore, from 2006 to 2010. Chinese, Malay, and Indian patients were compared with patients of other ethnic groups. Multiple logistic regression analyses determined differences in survival rates after adjusting for demographics, anatomic and physiologic ISS and revised trauma score, mechanism or type of injury.

Results

A total of 4,186 patients (66.4 % of the database) met the inclusion criteria. Most patients were male (76.3 %) and young (mean age 40 years). Using Chinese as the reference group, we found no statistically significant differences in unadjusted or adjusted mortality rates among the ethnic groups. Independent predictors of mortality included age [odds ratio (OR) 1.05, 95 % confidence interval (CI) 1.03–1.06, p < 0.0001], presence of severe head injury (OR 1.75, 95 % CI 1.13–2.69, p = 0.012), and increasing ISS (p < 0.0001).

Conclusions

Ethnicity is not an independent predictor of trauma mortality outcomes in the Singapore population. Our findings contrast with those from the United States, where race/ethnicity (Black and Hispanic) remains a strong independent risk factor for trauma mortality. This study attests to the success of the Singapore health care/trauma system in delivering the same quality of care regardless of ethnicity.
Ethanol effect on batch and fed-batchArthrospira platensisgrowth
Authors: Bezerra Raquel P , Matsudo Marcelo C , Pérez Mora Lina S , Sato Sunao , de Carvalho João C Monteiro
Published: February 2014

The ability of Arthrospira platensis to use ethanol as a carbon and energy source was investigated by batch process and fed-batch process. A. platensis was cultivated under the effect of a single addition (batch process) and a daily pulse feeding (fed-batch process) of pure ethanol, at different concentrations, to evaluate cell concentration (X) and specific growth rate (μ). A marked increase was observed in the cell concentration of A. platensis in runs with ethanol addition when compared to control cultures without ethanol addition. The fed-batch process using an ethanol concentration of 38 mg L−1 days−1 reached the maximum cell concentration of 2,393 ± 241 mg L−1, about 1.5-fold that obtained in the control culture. In all experiments, the maximum specific growth rate was observed in the early exponential phase of cell growth. In the fed-batch process, μ decreased more slowly than in the batch process and control culture, resulting in the highest final cell concentration. Ethanol can be used as a feasible carbon and energy source for A. platensis growth via a fed-batch process.
Adjoint-based control of loud events in a turbulent jet
Authors: Kim Jeonglae , Bodony Daniel J. , Freund Jonathan B.
Published: February 2014

Efforts to reduce the noise from turbulent jets at fixed flow conditions, with aircraft noise as the principal technological motivation, have generally involved some degree of parametric empiricism often based upon a series of trial-and-error testing. As a result, it is unclear if the modest reductions found, in rare cases that do not greatly affect the flow field or incur prohibitive losses, are near the limit of what can be accomplished or if there are undiscovered opportunities for more substantive reductions with better designs or active control. We assess this using an adjoint-based optimization procedure in conjunction with an experimentally validated large-eddy simulation of a Mach 1.3 turbulent jet. The adjoint solution provides a definitive direction in which to adjust a model control actuation in order to reduce noise, providing guidance that seems lacking by any other current means. It is found that three conjugate-gradient iterations in the control space provide ∼3.5 dB of reduction, comparable to other reductions found empirically. The control seems to work by disrupting the coherence of acoustically efficient axisymmetric flow structures. The control and noise-reduction mechanisms are informative, but also suggest that any significantly quieter state would not be a simple perturbation from the uncontrolled jet. Additional iterations might reduce noise more significantly, but there might be only modest opportunities to reduce the sound from simple round turbulent jets without radical changes or relatively sophisticated controls. Though it is difficult to prove any behaviour in a global space of actuations, there does not seem to be a direct route based upon a local sensitivity gradient to substantially quieting a jet, even with an unrealistically flexible actuation. More complex jets or other noisy flows may be more amenable to control, in which case the adjoint-based optimization procedure demonstrated here could provide invaluable engineering guidance.
Is the tapeworm able to affect tissue Pb-concentrations in white rat?
Authors: ČADKOVÁ ZUZANA , MIHOLOVÁ DANIELA , SZÁKOVÁ JIŘINA , VÁLEK PETR , JANKOVSKÁ IVANA , LANGROVÁ IVA
Published: February 2014

The effect of gastrointestinal helminths on Pb accumulation in the host body is ambiguous. A laboratory experiment withRattus norvegicus/Hymenolepis diminutamodel was conducted to determine Pb toxicokinetics in a terrestrial host-parasite system. The ET-AAS or ICP–OES techniques were used to determine Pb concentrations (CPb) in both tapeworms and host tissues (kidney, liver, bone, testes, muscle and intestinal wall). Concerning the entire host-parasite system, the highest CPbwere detected inH. diminuta. Rat kidneys and bone were the only two tissues whose mean Pb levels were lower in parasitized animals than they were in non-infected subjects after both levels of exposure. At low Pb exposure, parasitization slightly changed the Pb toxicokinetics in the host body. However, with respect to tissue at the same exposure level, no significant differences were detected between the parasitized and non-parasitized animals and no significant correlations were found between CPbin tapeworms and those of host tissues. The results of this study indicate thatH. diminutadoes not protect rat from elevated Pb exposure even if tapeworm accumulates a higher portion of ingested Pb dose compared with that of the most Pb-loaded host soft tissue. The portion of Pb dose accumulated inH. diminutacorrelates positively with parasite biomass.
Distribution ofEscherichia colistrains harbouring Shiga toxin-producingE. coli(STEC)-associated virulence factors (stx1, stx2, eae, ehxA) from very young calves in the North Island of New Zealand
Authors: IRSHAD H. , COOKSON A. L. , PRATTLEY D. J. , DUFOUR M. , FRENCH N. P.
Published: February 2014

The objective of this study was to determine the distribution of Shiga toxin-producingEscherichia coli(STEC) virulence markers (stx1,stx2,eae,ehxA) inE. colistrains isolated from young calves aged fewer than 7 days (bobby calves). In total, 299 recto-anal mucosal swabs were collected from animals at two slaughter plants and inoculated onto tryptone bile X-glucuronide and sorbitol MacConkey agar supplemented with cefixime and potassium tellurite. Isolates were analysed using multiplex polymerase chain reaction to detectstx1,stx2,eaeandehxAgenes. The most common combination of virulence markers wereeae, ehxA(n = 35) followed byeae(n = 9). In total, STEC and atypical enteropathogenicE. coli(aEPEC) were isolated from 8/299 (2·6%) and 37/299 (12·3%) calves, respectively. All the isolates could be assigned to 15 genotype clusters with >70% similarity cut-off usingXbaI pulsed-field gel electrophoresis. It may be concluded that healthy calves from the dairy industry are asymptomatic carriers of a diverse population of STEC and aEPEC in New Zealand.
Does “Religious Violence” Exist?: An Argument Against Essentialism with Particular Reference to the Conquest of the Americas
Authors: Osborn Ronald E.
Published: February 2014

Since the terrorist attacks of September 11, 2001, there has been a dramatic increase in social scientific literature on the topic of “religious violence,” much of it arguing that there is a uniquely intense and disturbing connection between religion and political conflict and bloodshed. In this article, I challenge mainstream accounts of “religious violence” with an illustrative example from the 16th century of the theoretical and empirical problems with all such essentialist claims. The terms employed in the construction of “religious violence” might today just as easily be applied to the violence of the putatively “secular” nation-state. Furthermore, framing the debate in these sharp binary terms, as William Cavanaugh compellingly demonstrates, is itself part of a political project that had a very particular historical beginning and that conceals as much as it reveals about the nature of violence, both in the past and in the present.
The Effects of the Relationships Between Object Features on Multiple-Identity Tracking
Authors: Huang Duan , Zhang Yongbo , Zhang Kan
Published: February 2014

Simultaneous tracking of multiple moving objects is essential in tasks such as traffic control, automobile driving, and scene surveillance. Recently, an increasing number of studies have focused on the roles of object identity and location binding in unique target tracking tasks, but contradictory results have been reported. In the present study, we introduced for the first time the Stroop stimuli of Chinese characters to the multiple-identity tracking paradigm, taking advantage of the ease to control the overall size, familiarity, and visual complexity of the Chinese characters. The results showed that when the observers were asked to track unique objects that bear two distinct features, the feature conflict disrupted the tracking performance, even when the given object has a distinctive identity. Our data revealed that the internal disaccord of semantic and physical features on an object can disturb the identity-location binding process in a multiple-identity tracking task, but does not affect the location information significantly.
Post modification of MOF derived carbon via g-C3N4 entrapment for an efficient metal-free oxygen reduction reaction
Authors: Pandiaraj Sekar , Aiyappa Harshitha Barike , Banerjee Rahul , Kurungot Sreekumar
Published: February 2014

High surface area carbon with a nitrogen content of 7.0% is derived from MOF via in situ g-C3N4 formation.
Iminosugar-based glycopolypeptides: glycosidase inhibition with bioinspired glycoprotein analogue micellar self-assemblies
Authors: Bonduelle Colin , Huang Jin , Mena-Barragán Teresa , Ortiz Mellet Carmen , Decroocq Camille , Etamé Emile , Heise Andreas , Compain Philippe , Lecommandoux Sebastien
Published: February 2014

Glycosidase inhibition with bioinspired glycoprotein analogue micellar self-assemblies.
“Converting” an hexametallic MnIII wheel to a dodecametallic MnIII wheel via ligand oximation
Authors: Sanz Sergio , Frost Jamie M. , Pitak Mateusz B. , Coles Simon J. , Piligkos Stergios , Lusby Paul J. , Brechin Euan K.
Published: February 2014

Ligand oximation “converts” an hexametallic MnIII wheel into a dodecametallic MnIII wheel, while the magnetic exchange switches from ferro- to antiferromagnetic.
Raman spectroscopy and density functional theory analyses of the melt structure in a Li2B4O7 crystal growth system
Authors: Wan Songming , Tang Xiaolu , Sun Yulong , Zhang Guochun , You Jinglin , Fu Peizhen
Published: February 2014

Raman spectroscopy and density functional theory methods were applied to study the Li2B4O7 melt structure; a new boron–oxygen chain structure was found for the first time.
Photodissociation dynamics of propargylene, HCCCH
Authors: Giegerich Jens , Petersen Jens , Mitrić Roland , Fischer Ingo
Published: February 2014

We report a joint theoretical and experimental study on the photodissociation of the C3H2 isomer propargylene, HCCCH, combining velocity map imaging with nonadiabatic surface hopping calculations.
Acoustic bubble sorting for ultrasound contrast agent enrichment
Authors: Segers Tim , Versluis Michel
Published: February 2014

Resonant microbubbles are sorted from a polydisperse ultrasound contrast agent suspension in an acoustic bubble sorting chip.
A smartphone platform for the quantification of vitamin D levels
Authors: Lee Seoho , Oncescu Vlad , Mancuso Matt , Mehta Saurabh , Erickson David
Published: February 2014

We present a smartphone platform for the quantification of vitamin D status.
Pressure-induced phase transitions of TiO2 nanosheets with high reactive {001} facets
Authors: Li Quanjun , Cheng Benyuan , Tian Baoli , Liu Ran , Liu Bo , Wang Fei , Chen Zhiqiang , Zou Bo , Cui Tian , Liu Bingbing
Published: February 2014

TiO2 nanosheets with highly reactive {001} facets show ultralow compressibility compared to those of the corresponding TiO2 nanoparticles and bulk.
Synergy effects of magnetic silica nanostructures for drug delivery applications
Authors: Otero-Lorenzo Ruth , Dávila-Ibáñez Ana B. , Comesaña-Hermo Miguel , Correa-Duarte Miguel A. , Salgueiriño Verónica
Published: February 2014

This article presents a capable strategy of using hybrid nanostructures to improve the magnetic-based performance jointly with the internalization process into cells, for drug delivery applications.
Electrochemiluminescence resonance energy transfer between graphene quantum dots and gold nanoparticles for DNA damage detection
Authors: Lu Qian , Wei Wei , Zhou Zhenxian , Zhou Zhixin , Zhang Yuanjian , Liu Songqin
Published: February 2014

Electrochemiluminescence resonance energy transfer between graphene quantum dots (GQDs) and Au nanoparticles results in the electrochemiluminescence signal of the GQDs being quenched or recovering.
Towards a carbon independent and CO2-free electrochemical membrane process for NH3 synthesis
Authors: Kugler K. , Ohs B. , Scholz M. , Wessling M.
Published: February 2014

A new NH3 synthesis process using an electrochemical membrane reactor including N2 production and product separation is modelled in Aspen+.
Synthesis, structures and DFT calculations of 2-(4,6-dimethyl pyrimidyl)selenolate complexes of Cu(i), Ag(i) and Au(i) and their conversion into metal selenide nanocrystals
Authors: Sharma Rakesh K. , Wadawale Amey , Kedarnath G. , Manna Debashree , Ghanty Tapan K. , Vishwanadh B. , Jain Vimal K.
Published: February 2014

Dimethyl pyrimidylselenolates of Cu(i), Ag(i) and Au(i) were synthesized and utilized as precursors for preparation of the respective metal selenide nanocrystals.
Solution synthesis of metal oxides for electrochemical energy storage applications
Authors: Xia Xinhui , Zhang Yongqi , Chao Dongliang , Guan Cao , Zhang Yijun , Li Lu , Ge Xiang , Bacho Ignacio Mínguez , Tu Jiangping , Fan Hong Jin
Published: February 2014

Various solution-based synthesis methods for common metal oxide nanostructures and associated reaction mechanisms are reviewed.
On the fate of hydrogen during zirconium oxidation by water: effect of oxygen dissolution in α-Zr
Authors: Lindgren Mikaela , Panas Itai
Published: February 2014

Constraints and opportunities for beneficial cathodic hydrogen evolution owing to the anodic oxidation of zirconium by water.
A bienzyme-immobilized highly efficient niobium oxide nanorod platform for biomedical application
Authors: Singh Chandan , Pandey M. K. , Biradar A. M. , Srivastava A. K. , Sumana Gajjala
Published: February 2014

Electrophoretically deposited niobium oxide nanorods have been utilized to fabricate a high performance biosensor for specific cholesterol detection.
A large area, flexible polyaniline/buckypaper composite with a core–shell structure for efficient supercapacitors
Authors: He Shaoqing , Wei Jinquan , Guo Fengmei , Xu Ruiqiao , Li Can , Cui Xian , Zhu Hongwei , Wang Kunlin , Wu Dehai
Published: February 2014

We fabricated efficient polyaniline (PANI)/buckypaper supercapacitors based on the continuous growth of flexible carbon nanotube (CNT) films and electro-deposition technique.
Redox signal regulation via nNOS phosphorylation at Ser847 in PC12 cells and rat cerebellar granule neurons
Authors: Kasamatsu Shingo , Watanabe Yasuo , Sawa Tomohiro , Akaike Takaaki , Ihara Hideshi
Published: February 2014

Phosphorylation is considered a main mechanism modulating nNOS (neuronal nitric oxide synthase) function to reduce NO production. In the present study, the effects of nNOS phosphorylation on redox signalling, including that of NO, ROS (reactive oxygen species), and 8-nitro-cGMP (8-nitroguanosine 3′,5′-cyclic monophosphate), a downstream messenger of redox signalling, were investigated. In vitro experiments revealed that a phosphorylation-mimic mutant of nNOS (Ser847 replaced with aspartic acid, 847D) increased uncoupling to produce a superoxide. In addition, nicotine, which triggers an influx of Ca2+, induced more ROS and 8-nitro-cGMP production in 847D-expressing PC12 cells than WT (wild-type)-expressing cells. Additionally, nicotine-induced phosphorylation of nNOS at Ser847 and increased ROS and 8-nitro-cGMP production in rat CGNs (cerebellar granule neurons). In CGNs, the NOS (nitric oxide synthase) inhibitor L-NAME (NG-nitro-L-arginine methyl ester) and superoxide dismutase completely inhibited ROS and 8-nitro-cGMP production, whereas the CaMK (Ca2+/calmodulin-dependent protein kinase) inhibitor KN93 mildly reduced this effect. Nicotine induced HO-1 (haem oxygenase 1) expression in CGNs and showed cytoprotective effects against apoptosis. Moreover, 8-nitro-cGMP treatment showed identical effects that were attenuated by KN93 pre-treatment. The present paper provides the first substantial corroboration for the biological effects of nNOS phosphorylation at Ser847 on redox signalling, including ROS and intracellular 8-nitro-cGMP generation in neurons, which possibly play roles in neuroprotection.
Design and properties of a cryogenic dip-stick scanning tunneling microscope with capacitive coarse approach control
Authors: Schlegel R. , Hänke T. , Baumann D. , Kaiser M. , Nag P. K. , Voigtländer R. , Lindackers D. , Büchner B. , Hess C.
Published: February 2014

We present the design, setup, and operation of a new dip-stick scanning tunneling microscope. Its special design allows measurements in the temperature range from 4.7 K up to room temperature, where cryogenic vacuum conditions are maintained during the measurement. The system fits into every 4He vessel with a bore of 50 mm, e.g., a transport dewar or a magnet bath cryostat. The microscope is equipped with a cleaving mechanism for cleaving single crystals in the whole temperature range and under cryogenic vacuum conditions. For the tip approach, a capacitive automated coarse approach is implemented. We present test measurements on the charge density wave system 2H-NbSe2 and the superconductor LiFeAs which demonstrate scanning tunneling microscopy and spectroscopy data acquisition with high stability, high spatial resolution at variable temperatures and in high magnetic fields.
Accurate description of torsion potentials in conjugated polymers using density functionals with reduced self-interaction error
Authors: Sutton Christopher , Körzdörfer Thomas , Gray Matthew T. , Brunsfeld Max , Parrish Robert M. , Sherrill C. David , Sears John S. , Brédas Jean-Luc
Published: February 2014

We investigate the torsion potentials in two prototypical π-conjugated polymers, polyacetylene and polydiacetylene, as a function of chain length using different flavors of density functional theory. Our study provides a quantitative analysis of the delocalization error in standard semilocal and hybrid density functionals and demonstrates how it can influence structural and thermodynamic properties. The delocalization error is quantified by evaluating the many-electron self-interaction error (MESIE) for fractional electron numbers, which allows us to establish a direct connection between the MESIE and the error in the torsion barriers. The use of non-empirically tuned long-range corrected hybrid functionals results in a very significant reduction of the MESIE and leads to an improved description of torsion barrier heights. In addition, we demonstrate how our analysis allows the determination of the effective conjugation length in polyacetylene and polydiacetylene chains.
Charge/mass dynamic structure factors of water and applications to dielectric friction and electroacoustic conversion
Authors: Sedlmeier Felix , Shadkhoo Shahriar , Bruinsma Robijn , Netz Roland R.
Published: February 2014

We determine time correlation functions and dynamic structure factors of the number and charge density of liquid water from molecular dynamics simulations. Using these correlation functions we consider dielectric friction and electro-acoustic coupling effects via linear response theory. From charge-charge correlations, the drag force on a moving point charge is derived and found to be maximal at a velocity of around 300 m/s. Strong deviations in the resulting friction coefficients from approximate theory employing a single Debye relaxation mode are found that are due to non-Debye-like resonances at high frequencies. From charge-mass cross-correlations the ultrasonic vibration potential is derived, which characterizes the conversion of acoustic waves into electric time-varying potentials. Along the dispersion relation for normal sound waves in water, the ultrasonic vibration potential is shown to strongly vary and to increase for larger wavelengths.
Magnetic properties and electronic structures of (YTiO3)2/(BaTiO3)n superlattices
Authors: Zhou P. X. , Liu H. M. , Yan Z. B. , Dong S. , Liu J.-M.
Published: February 2014

The magnetic properties and electronic structures of (YTiO3)2/(BaTiO3)n superlattices are investigated using the first-principles calculations. It is revealed that the in-plane compressive strain results in the A-type antiferromagnetic order in the YTiO3 component. Surprisingly, the Ti ions in BaTiO3 layers exhibit a weak ferromagnetic order for n = 4. The ferromagnetism in the BaTiO3 layers near the interface is related to the polar discontinuity of YTiO3 and ferroelectric polarization of BaTiO3. The electronic structures indicate that the n = 4 superlattice shows the two-dimensional electron gas at the interface.
Nanosecond switching in GeSe phase change memory films by atomic force microscopy
Authors: Bosse James L. , Grishin Ilya , Gyu Choi Yong , Cheong Byung-ki , Lee Suyoun , Kolosov Oleg V. , Huey Bryan D.
Published: February 2014

Nanosecond scale threshold switching is investigated with conducting atomic force microscopy (AFM) for an amorphous GeSe film. Switched bits exhibit 2–3 orders of magnitude variations in conductivity, as demonstrated in phase change based memory devices. Through the nm-scale AFM probe, this crystallization was achieved with pulse durations of as low as 15 ns, the fastest reported with scanning probe based methods. Conductance AFM imaging of the switched bits further reveals correlations between the switched volume, pulse amplitude, and pulse duration. The influence of film heterogeneities on switching is also directly detected, which is of tremendous importance for optimal device performance.
Rapid and multi-step, patterned electrophoretic deposition of nanocrystals using electrodes covered with dielectric barriers
Authors: Whan Lee Seung , Zhang Datong , Herman Irving P.
Published: February 2014

The rates of electrophoretic deposition (EPD) of CdSe nanocrystals (NCs) are approximately the same when powering electrodes on either the frontside or backside of thick dielectrics when the resistance of the NC colloid exceeds that of the dielectric barrier. Using electrodes with dielectric barriers enables conformal coverage over topography on the frontside. It also enables multistep processing when combined with powering patterned frontside electrodes for localized EPD. Powering patterned backside electrodes produces film features that are wider than the electrode dimensions, which is consistent with the results of modeling the electric field profile.
Multiscale modeling of polyisoprene on graphite
Authors: Pandey Yogendra Narayan , Brayton Alexander , Burkhart Craig , Papakonstantopoulos George J. , Doxastakis Manolis
Published: February 2014

The local dynamics and the conformational properties of polyisoprene next to a smooth graphite surface constructed by graphene layers are studied by a multiscale methodology. First, fully atomistic molecular dynamics simulations of oligomers next to the surface are performed. Subsequently, Monte Carlo simulations of a systematically derived coarse-grained model generate numerous uncorrelated structures for polymer systems. A new reverse backmapping strategy is presented that reintroduces atomistic detail. Finally, multiple extensive fully atomistic simulations with large systems of long macromolecules are employed to examine local dynamics in proximity to graphite. Polyisoprene repeat units arrange close to a parallel configuration with chains exhibiting a distribution of contact lengths. Efficient Monte Carlo algorithms with the coarse-grain model are capable of sampling these distributions for any molecular weight in quantitative agreement with predictions from atomistic models. Furthermore, molecular dynamics simulations with well-equilibrated systems at all length-scales support an increased dynamic heterogeneity that is emerging from both intermolecular interactions with the flat surface and intramolecular cooperativity. This study provides a detailed comprehensive picture of polyisoprene on a flat surface and consists of an effort to characterize such systems in atomistic detail.
Magnetostrictive vibrations model of a three-phase transformer core and the contribution of the fifth harmonic in the grid voltage
Authors: Gorji Ghalamestani Setareh , Vandevelde Lieven , Dirckx Joris J. J. , Melkebeek Jan A. A.
Published: February 2014

The effect of the fifth harmonic in the grid voltage (with fundamental frequency of 50 Hz) on the vibrations of a three-phase transformer core is computed, since such harmonic has the largest contribution in the European grid voltage. The computational method is a two-dimensional (2D) finite element technique. The modal vibrations under various magnetisations (viz with different fifth harmonic components) are compared with those obtained under a purely sinusoidal magnetisation and showed that the variations for the 100 Hz harmonic of the vibrations are small. However, the 200 Hz harmonic showed a significant increase when a fifth harmonic was present on the applied voltage. In fact, the presence of a fundamental component with 50 Hz frequency and a fifth harmonic on the magnetisation signal generates a 200 Hz harmonic on the magnetostriction strains (and the magnetic forces), and thus this harmonic increases significantly.
Si incorporation from the seed into Ge stripes crystallized using rapid melt growth
Authors: Bai Xue , Chen Chien-Yu , Griffin Peter B. , Plummer James D.
Published: February 2014

Ge stripes grown by rapid melt growth (RMG) have produced defect free single crystals with excellent device characteristics. However, in some cases significant Si concentrations have been observed in the stripes, far from the seed region. In this paper, we anneal Ge RMG stripes at temperatures ranging from 950 °C to 1150 °C for different time periods and show that the measured composition profiles match a model in which complete mixing in the melt is assumed. The model also assumes that the average Si concentration in the RMG stripe equals the equilibrium liquidus concentration at the annealing temperature. This paper outlines a method to predict the profile of Si absorbed from the seed region during RMG. The conclusions from this paper have important implications for minimizing Si contamination in RMG grown stripes.
Validity conditions for stochastic chemical kinetics in diffusion-limited systems
Authors: Gillespie Daniel T. , Petzold Linda R. , Seitaridou Effrosyni
Published: February 2014

The chemical master equation (CME) and the mathematically equivalent stochastic simulation algorithm (SSA) assume that the reactant molecules in a chemically reacting system are “dilute” and “well-mixed” throughout the containing volume. Here we clarify what those two conditions mean, and we show why their satisfaction is necessary in order for bimolecular reactions to physically occur in the manner assumed by the CME and the SSA. We prove that these conditions are closely connected, in that a system will stay well-mixed if and only if it is dilute. We explore the implications of these validity conditions for the reaction-diffusion (or spatially inhomogeneous) extensions of the CME and the SSA to systems whose containing volumes are not necessarily well-mixed, but can be partitioned into cubical subvolumes (voxels) that are. We show that the validity conditions, together with an additional condition that is needed to ensure the physical validity of the diffusion-induced jump probability rates of molecules between voxels, require the voxel edge length to have a strictly positive lower bound. We prove that if the voxel edge length is steadily decreased in a way that respects that lower bound, the average rate at which bimolecular reactions occur in the reaction-diffusion CME and SSA will remain constant, while the average rate of diffusive transfer reactions will increase as the inverse square of the voxel edge length. We conclude that even though the reaction-diffusion CME and SSA are inherently approximate, and cannot be made exact by shrinking the voxel size to zero, they should nevertheless be useful in many practical situations.
A coarse-grained model for the simulations of biomolecular interactions in cellular environments
Authors: Xie Zhong-Ru , Chen Jiawen , Wu Yinghao
Published: February 2014

The interactions of bio-molecules constitute the key steps of cellular functions. However, in vivo binding properties differ significantly from their in vitro measurements due to the heterogeneity of cellular environments. Here we introduce a coarse-grained model based on rigid-body representation to study how factors such as cellular crowding and membrane confinement affect molecular binding. The macroscopic parameters such as the equilibrium constant and the kinetic rate constant are calibrated by adjusting the microscopic coefficients used in the numerical simulations. By changing these model parameters that are experimentally approachable, we are able to study the kinetic and thermodynamic properties of molecular binding, as well as the effects caused by specific cellular environments. We investigate the volumetric effects of crowded intracellular space on bio-molecular diffusion and diffusion-limited reactions. Furthermore, the binding constants of membrane proteins are currently difficult to measure. We provide quantitative estimations about how the binding of membrane proteins deviates from soluble proteins under different degrees of membrane confinements. The simulation results provide biological insights to the functions of membrane receptors on cell surfaces. Overall, our studies establish a connection between the details of molecular interactions and the heterogeneity of cellular environments.
Propagation of terahertz electromagnetic wave in plasma with inhomogeneous collision frequency
Authors: Tian Yuan , Han YiPing , Ling YingJie , Ai Xia
Published: February 2014

In this paper, we investigate the absorption spectra of terahertz electromagnetic wave in plasma with inhomogeneous collision frequency. Profiles are introduced to describe the non-uniformity of collision frequency. It is interesting to find that when the plasma is collision frequency inhomogeneous, the absorption spectrum would decreases faster than that in uniform plasma. And the rate of decreasing would be different when the profile changes. Two parameters are set up to predict how the profiles affect the absorption spectra. Furthermore, the effects of electron density are also considered.
Profiling of the injected charge drift current transients by cross-sectional scanning technique
Authors: Gaubas E. , Ceponis T. , Pavlov J. , Baskevicius A.
Published: February 2014

The electric field distribution and charge drift currents in Si particle detectors are analyzed. Profiling of the injected charge drift current transients has been implemented by varying charge injection position within a cross-sectional boundary of the particle detector. The obtained profiles of the induction current density and duration of the injected charge drift pulses fit well the simulated current variations. Induction current transients have been interpreted by different stages of the bipolar and monopolar drift of the injected carriers. Profiles of the injected charge current transients registered in the non-irradiated and neutron irradiated Si diodes are compared. It has been shown that the mixed regime of the competing processes of drift, recombination, and diffusion appears in the measured current profiles on the irradiated samples. The impact of the avalanche effects can be ignored based on the investigations presented. It has been shown that even a simplified dynamic model enabled us to reproduce the main features of the profiled transients of induced charge drift current.
Self-generation of dissipative solitons in magnonic quasicrystal active ring resonator
Authors: Grishin S. V. , Beginin E. N. , Morozova M. A. , Sharaevskii Yu. P. , Nikitov S. A.
Published: February 2014

Self-generation of dissipative solitons in the magnonic quasicrystal (MQC) active ring resonator is studied theoretically and experimentally. The developed magnonic crystal has quasiperiodic Fibonacci type structure. Frequency selectivity of the MQC together with the parametric three-wave decay of magnetostatic surface spin wave (MSSW) leads to the dissipative soliton self-generation. The transfer matrix method is used to describe MQC transmission responses. Besides, the model of MQC active ring resonator is suggested. The model includes three coupled differential equations describing the parametric decay of MSSW and two differential equations of linear oscillators describing the frequency selectivity of MQC. Numerical simulation results of dissipative soliton self-generation are in a fair agreement with experimental data.
Imprinting of fine-scale magnetic patterns in electroplated hard magnetic films using magnetic foil masks
Authors: Oniku Ololade D. , Ryiz Paul V. , Garraud Alexandra , Arnold David P.
Published: February 2014

This paper presents a batch-fabrication approach to imprint complex magnetic pole patterns (perpendicular north/south poles) into hard magnetic films using fine-scale, laser-machined iron foil “masks.” In this approach, pulsed magnetic fields varying between 0.1 and 1.0 T are used in conjunction with the field-concentrating effect of the iron foil masks to selectively reverse the magnetization of selected regions of 10-μm-thick Co80Pt20 films (Br = 1 T, Hci = 340 kA/m). Simple stripe array patterns are systematically studied both experimentally and via simulation, achieving patterned feature sizes (poles) down to 30 μm. Double exposures are also explored to create checkerboard patterns from simple stripe-like masks. Finally, masks with more complex patterns are used to demonstrate the viability of the approach to imprint arbitrary features.