bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel phosphorus doped carbon nitride modified TiO2nanotube arrays with improved photoelectrochemical performance
Authors: Su Jingyang , Geng Ping , Li Xinyong , Zhao Qidong , Quan Xie , Chen Guohua
Published: September 2015

Novel phosphorus-doped graphitic-carbon nitride (P-C3N4) modified vertically aligned TiO2nanotube arrays (NTs) were designed and synthesized.
Total syntheses of natural products containing spirocarbocycles
Authors: Smith Laura K. , Baxendale Ian R.
Published: September 2015

The spiro motif is becoming an increasingly prevalent structure in medicinal and organic chemistry. The total syntheses of natural products containing all-carbon spirocycles is reviewed.
Alkylation/1,2-aryl migration of α-aryl allylic alcohols with α-carbonyl alkyl bromides using visible-light photoredox catalysis
Authors: Li Yang , Liu Bang , Ouyang Xuan-Hui , Song Ren-Jie , Li Jin-Heng
Published: September 2015

A visible-light-induced alkene difunctionalization strategy is described for 1,5-dicarbonyl compound synthesis through alkylation and 1,2-aryl migration.
Egg shell membrane – a potential natural scaffold for human meniscal tissue engineering: an in vitro study
Authors: Pillai Mamatha M. , Akshaya T. R. , Elakkiya V. , Gopinathan J. , Sahanand K. Santosh , Rai B. K. Dinakar , Bhattacharyya Amitava , Selvakumar R.
Published: September 2015

Enhanced human primary meniscal cell proliferation in autoclaved egg shell membrane.
Capture of radioactive cations from water using niobate nanomaterials with layered and tunnel structures
Authors: Sun Jin , Liu Long , Zhao Xiaoliang , Yang Shuanglei , Komarneni Sridhar , Yang Dongjiang
Published: September 2015

Layered KNb3O8nanorods and tunnel structured Na2Nb2O6·H2O nanofibers, display ideal properties for removal of radioactive cations such as Sr2+, Ba2+(as simulant for226Ra2+) and Cs+ions from wastewater through ion exchange process.
Facile synthesis of a CNT@Fe@SiO2 ternary composite with enhanced microwave absorption performance
Authors: Lv Hualiang , Ji Guangbin , Zhang Haiqian , Du Youwei
Published: September 2015

The CNTs@Fe@SiO2 ternary core-structure was prepared by a simple two-step approach consisting a pyrolysis process and then decomposition. At a thin thickness of 1.5 mm, the optimal reflection loss value of the ternary composite is as high as −14.2 dB.
Enhanced field emission properties of ZnO nanorods by surface modification
Authors: Ye Zhixiang , Ji Xiaohong , Zhang Qinyuan
Published: September 2015

ZnO nanorods on Si substrates were synthesized by a simple vapor phase transport method, and FE property of these ZnO nanorods was improved by a two-step surface modification process.
Design and development of Co3O4/NiO composite nanofibers for the application of highly sensitive and selective non-enzymatic glucose sensors
Authors: Ramasamy Ramachandran , Ramachandran K. , Philip Geo George , Ramachandran Rasu , Therese Helen Annal , Gnana kumar G.
Published: September 2015

Cobaltosic oxide/nickel oxide (Co3O4/NiO) composite nanofibers were synthesizedviaan electrospinning technique and their electrocatalytic activities toward non-enzymatic glucose sensors were evaluated in detail.
Synthesis of regenerable Zn(OH)2nanoparticle-loaded activated carbon for the ultrasound-assisted removal of malachite green: optimization, isotherm and kinetics
Authors: Bazrafshan A. A. , Hajati S. , Ghaedi M.
Published: September 2015

Highly regenerable, safe, green and rapid adsorption by loading trace amounts of Zn(OH)2nanoparticles on AC with high uptake capacity.
Facile fabrication of three-dimensional graphene microspheres using β-cyclodextrin aggregates as substrates and their application for midecamycin sensing
Authors: Zhu Xiaofei , Xu Jingkun , Duan Xuemin , Lu Limin , Zhang Kaixin , Gao Yansha , Dong Liqi , Sun Hui
Published: September 2015

Three-dimensional (3D) graphene (GR) microspheres have been successfully prepared for the first time using β-cyclodextrin aggregates (β-CDAs) as substrates, which could be easily obtained from concentrated aqueous solutions of β-CD.
Regioselective synthesis of a vitamin K3 based dihydrobenzophenazine derivative: its novel crystal structure and DFT studies
Authors: Chadar Dattatray , Rao Soniya S. , Gejji Shridhar P. , Ugale Bharat , Nagaraja C. M. , Nikalje Milind , Salunke-Gawali Sunita
Published: September 2015

A novel regioselective synthesis of vitamin K3 based dihydrobenzophenazine is reported.
A novel strategy for screening new natural products by a combination of reversed-phase liquid chromatography fractionation and 13C NMR pattern recognition: the discovery of new anti-cancer flavone dimers from Dysosma versipellis (Hance)
Authors: Yang Zhi , Wu Youqian , Zhou Hui , Cao Xiaoji , Jiang Xinhang , Wang Kuiwu , Wu Shihua
Published: September 2015

A new screening strategy for the discovery of new natural products by a combination of reversed-phase liquid chromatography (RPLC) and 13C NMR pattern recognition.
An experimental and theoretical study on the regioselective synthesis of a new class of spiropyrrolothiazoles with quinoxaline motifs via a 1,3-dipolar cycloaddition reaction. An evaluation of DFT methods
Authors: Hamzehloueian Mahshid , Sarrafi Yaghoub , Aghaei Zahra
Published: September 2015

Evaluation of B3LYP/6-31G(d,p), wB97xD/6-31G(d,p) and M06-2X/6-31G(d,p) methods revealed the importance of π/π interactions in regio- and stereoselectivity of cycloaddition reactions.
Novel composite membranes based on sulfonated poly(ether ether ketone) and adenosine triphosphate for enhanced proton conduction
Authors: Yin Yongheng , Wang Jiahui , Jiang Shengtao , Yang Xin , Zhang Xuya , Cao Ying , Cao Li , Wu Hong
Published: September 2015

Novel SPEEK/ATP composite membranes were prepared via a facile method, achieving improved proton conductivity under different conditions.
Performance of cobalt titanate towards H2O2 based catalytic oxidation of lignin model compound
Authors: Shilpy Mariom , Ehsan Muhammad Ali , Ali Tammar Hussein , Abd Hamid Sharifah Bee , Ali Md. Eaqub
Published: September 2015

Mixed metal cobalt titanium oxide (CoTiO3) prepared by solution phase method has been evaluated for the liquid phase catalytic oxidation of vanillyl alcohol to vanillin using H2O2 as an oxygen source.
Bis-triazolyl BODIPYs: a simple dye with strong red-light emission
Authors: Guérin Charles , Jean-Gérard Ludivine , Octobre Guillaume , Pascal Simon , Maury Olivier , Pilet Guillaume , Ledoux Audrey , Andrioletti Bruno
Published: September 2015

The synthesis of an unprecedented bis-triazolyl BODIPY dye displaying a high quantum yield even in water is described.
Morphology control and supercapacitor performance of resorcinol–formaldehyde-based carbon particles upon Ni loading in an inverse emulsion system
Authors: Lei Qian , Song Huaihe , Zhou Dai , Zhang Su , Chen Xiaohong
Published: September 2015

Ni-doped resorcinol–formaldehyde-based carbon particles with controllable morphologies were prepared and their specific capacitances were investigated.
Proton donor modulating ESIPT-based fluorescent probes for highly sensitive and selective detection of Cu2+
Authors: Huang Liyan , Gu Biao , Su Wei , yin Peng , Li Haitao
Published: September 2015

Two novel ESIPT-based fluorescent probes for Cu2+ detection were developed. Altering the linker in probe molecules reversed their sensing behavior. Both probes exhibited high selectivity and sensitivity to Cu2+, and can be used for cell imaging.
CdS quantum dots immobilized on calcium alginate microbeads for rapid and selective detection of Hg2+ ions
Authors: Kumar Ambika , Dutta Raj Kumar
Published: September 2015

Immobilized CdS QDs for selective detection and pre-concentration of Hg2+.
Tribology and high-temperature oxidation behaviors of NiCrBSiFe composite coatings on Ti6Al4V alloy by laser cladding
Authors: Yu Peng-Cheng , Liu Xiu-Bo , Lu Xiao-Long , Qiao Shi-Jie , Zhai Yong-Jie , Zhu Gang-Xian , Wang Yong-Guang , Chen Yao
Published: September 2015

In order to improve the high-temperature wear and oxidation resistance of Ti6Al4V alloys simultaneously, NiCrBSiFe composite coatings were deposited on a Ti6Al4V alloy by laser cladding.
Enzyme activity enhancement of chondroitinase ABC I from Proteus vulgaris by site-directed mutagenesis
Authors: Chen Zhenya , Li Ye , Feng Yue , Chen Liang , Yuan Qipeng
Published: September 2015

Arg660 was found as a new active site and Asn795Ala and Trp818Ala mutants showed higher activities than the wild type based on molecular docking simulation analysis for the first time.
Photocurrent generation of nanofibers constructed using a complex of a gelator and a fullerene derivative
Authors: Xue Pengchong , Wang Panpan , Yao Boqi , Sun Jiabao , Gong Peng , Zhang Zhenqi , Lu Ran
Published: September 2015

Two-component xerogel film constructed by a carboxylic acid derivative and fullerene derivative could generate large photocurrent under light irradiation.
Controllable growth of uniform carbon nanotubes/carbon nanofibers on the surface of carbon fibers
Authors: Fan Wenxin , Wang Yanxiang , Chen Jiqiang , Yuan Yan , Li Aiguo , Wang Qifen , Wang Chengguo
Published: September 2015

Controllable growth of CNTs/CNFs on carbon fiber surface without degradation of tensile strength of carbon fibers.
In vivo pharmacokinetics of T2 contrast agents based on iron oxide nanoparticles: optimization of blood circulation times
Authors: Leal Manuel Pernia , Muñoz-Hernández Carmen , Berry Catherine C. , García-Martín María Luisa
Published: September 2015

PEGylated SPIONs using PEG MWs from 1500 to 8000 were intravenously injected in mice. Parametric MRI allowed us to track the pharmacokinetics and determine the effect of MW on the biodistribution and circulation times of PEG-SPIONs (HD < 50 nm).
Involvement of covalent interactions in the mode of action of PPARβ/δ antagonists
Authors: Kaupang Åsmund , Hildonen Siri , Halvorsen Trine G. , Mortén Magnus , Vik Anders , Hansen Trond Vidar
Published: September 2015

Investigations on the mode of action of several different chemical modulators of the peroxisome proliferator-activated receptor β/δ (PPARβ/δ) have been reported using MS and NMR experiments.
Reduced surface defects of organometallic perovskite by thermal annealing for highly efficient perovskite solar cells
Authors: Cui Peng , Fu Pengfei , Wei Dong , Li Meicheng , Song Dandan , Yue Xiaopeng , Li Yaoyao , Zhang Zhirong , Li Yingfeng , Mbengue Joseph Michel
Published: September 2015

The surface defects of the organometallic perovskite play an important role in the photovoltaic performance of solar cells, which depress the conversion efficiency and cause photocurrent hysteresis.
Cinchona alkaloid thiourea mediated asymmetric Mannich reaction of isocyanoacetates with isatin-derived ketimines and subsequent cyclization: enantioselective synthesis of spirooxindole imidazolines
Authors: Zhao Mei-Xin , Jing Lei , Zhou Hao , Shi Min
Published: September 2015

The organocatalyzed asymmetric Mannich reaction of isocyanoacetates with isatin ketimines and subsequent cyclization were developed, leading to spirooxindole imidazolines in high yields and excellent stereoselectivities.
Slip mechanisms in complex fluid flows
Authors: Hatzikiriakos Savvas G.
Published: September 2015

The classical no-slip boundary condition of fluid mechanics is not always a valid assumption for the flow of several classes of complex fluids including polymer melts, their blends, polymer solutions, microgels, glasses, suspensions and pastes.
Geometrically nonlinear deformation and the emergent behavior of polarons in soft matter
Authors: Li Xiaobao , Liu Liping , Sharma Pradeep
Published: September 2015

Mechanical strain can alter the electronic structure of both bulk semiconductors as well as nanostructures such as quantum dots.
Super-base-derived hypergolic ionic fuels with remarkably improved thermal stability
Authors: Zhang Wenquan , Qi Xiujuan , Huang Shi , Li Jinshan , Zhang Qinghua
Published: September 2015

Two series of super-base-derived hypergolic ionic liquids were synthesized, which all exhibit good hydrolytic stability to heat and expected hypergolic properties upon contact with WFNA.
Co-delivery of camptothecin and curcumin by cationic polymeric nanoparticles for synergistic colon cancer combination chemotherapy
Authors: Xiao Bo , Si Xiaoying , Han Moon Kwon , Viennois Emilie , Zhang Mingzhen , Merlin Didier
Published: September 2015

Camptothecin (CPT) and curcumin (CUR) have been co-loaded into cationic polymeric nanoparticles and exhibited strong synergistic effects against colon cancer cells.
Reliable H∞ filtering for stochastic spatial–temporal systems with sensor saturations and failures
Authors: Wang Dong , Shen Bo , Wang Zidong , Alsaadi Fuad Eid , Dobaie Abdullah M.
Published: September 2015

This study is concerned with the reliable H∞ filtering problem for a class of stochastic spatial–temporal systems with sensor saturations and failures. Different from the continuous spatial–temporal systems, the dynamic behaviour of the system under consideration evolves in a discrete rectangular region. The aim of this study is to estimate the system states through the measurements received from a set of sensors located at some specified points. In order to cater for more realistic signal transmission process, the phenomena of sensor saturations and sensor failures are taken into account. By using the vector reorganisation approach, the spatial–temporal system is first transformed into an equivalent ordinary differential dynamic system. Then, a filter is constructed and a sufficient condition is obtained under which the filtering error dynamics is asymptotically stable in probability and the H∞ performance requirement is met. On the basis of the analysis results, the desired reliable H∞ filter is designed. Finally, an illustrative example is given to show the effectiveness of the proposed filtering scheme.
Comparing Utility Scores in Common Spinal Radiculopathies: Results of a Prospective Valuation Study
Authors: Nayak Nikhil R. , Stephen James H. , Abdullah Kalil G. , Stein Sherman C. , Malhotra Neil R.
Published: September 2015

Study Design

Prospective observational study.

Objective

To determine whether preference-based health utility scores for common spinal radiculopathies vary by specific spinal level.

Methods

We employed a standard gamble study using the general public to calculate individual preference-based quality of life for four common radiculopathies: C6, C7, L5, and S1. We compared utility scores obtained for each level of radiculopathy with analysis of variance and t test. Multivariable regression was used to test the effects of the covariates age, sex, and years of education. We also reviewed the literature for publications reporting EuroQol-5 Dimensions (EQ-5D) scores for patients with radiculopathy.

Results

Two hundred participants were included in the study. Average utility for the four spinal levels fell within a narrow range (0.748 to 0.796). There were no statistically significant differences between lumbar and cervical radiculopathies, nor were there significant differences among the different spinal levels ( F = 0.0850, p = 0.086). Age and sex had no significant effect on utility scores. There was a significant correlation between years of education and utility values for S1 radiculopathy ( p = 0.037). On review of the literature, no study separated utility values by specific spinal level. EQ-5D utilities for both cervical and lumbar radiculopathy were considerably lower than the results of our study.

Conclusions

Utility values associated with the most common levels of cervical and lumbar radiculopathy do not significantly differ from each other, validating the current practice of grouping utility by spinal segment rather than by specific root levels. The discrepancy in average utility values between our study and the EQ-5D highlights the need to be mindful of the underlying instruments used when assessing outcomes studies from different sources.
Bolt from the Blue: A Large Foreign Body in the Maxillary Antrum Necessitating Delayed Primary Reconstruction with Split Cranial Bone Graft
Authors: Sharma Ramesh K. , Vemula GuruKarna , John Jerry R.
Published: September 2015

We report an unusual case of a large metallic foreign body embedded in the maxillary antrum leading to extensive bony destruction of the mid-face following a road side accident in a 12-year-old boy. There was extensive bony loss that necessitated reconstruction for both aesthetic and functional reasons. The same was accomplished by using split cranial bone graft in a delayed primary manner after a gap of 7 days following initial debridement. There was primary healing with good aesthetic and functional results.
Interdisciplinarity and anxiety
Authors: Lyne Raphael
Published: September 2015

At the level of institutional strategy, interdisciplinary research looks like a positive and productive exchange. At the personal level, where it is enmeshed with career progress, disciplinary anxieties and tensions at the interface between sometimes incommensurate kinds of thinking, there can be frictions and difficulties. These, however, are part of what makes such research so valuable, in that they enable individuals and groups within subjects on both sides to uncover those things that need to be better understood. This article forms part of an ongoing thematic collection dedicated to interdisciplinary research.
Tunable directional radiation of a dipole inside a cuboid slot on a dielectric substrate
Authors: Cheon Sangmo , Lee Chang-Won , Choe Jong-Ho , Park Q-Han
Published: September 2015

Far-field directional radiation of a single dipole in a cuboid slot is investigated in the presence of a dielectric substrate. Due to strong near field coupling between the dipole source and the surfaces of the slot and the dielectric, the far-field radiation shows strongly anisotropic pattern depending on the dipole radiation energy. By tuning local resonances within the air-slot interface or the substrate-slot interface, highly directional radiation either to free space or to the substrate space can be obtained. In the visible spectrum ranging from 1.2 eV to 3.5 eV, up to 18 fold directivity can be obtained. The up-to-down ratio can be tuned from −7.5 dB to 10 dB. We identify induced eigenmodes responsible for highly unidirectional radiations as a function of the emitter spectrum and slot thickness to assess controllability of radiation power and direction.
The low-temperature heat capacity of fullerite C60
Authors: Bagatskii M. I. , Sumarokov V. V. , Barabashko M. S. , Dolbin A. V. , Sundqvist B.
Published: September 2015

The heat capacity at constant pressure of fullerite C60 has been investigated using an adiabatic calorimeter in a temperature range from 1.2 to 120 K. Our results and literature data have been analyzed in a temperature interval from 0.2 to 300 K. The contributions of the intramolecular and lattice vibrations into the heat capacity of C60 have been separated. The contribution of the intramolecular vibration becomes significant above 50 K. Below 2.3 K the experimental temperature dependence of the heat capacity of C60 is described by the linear and cubic terms. The limiting Debye temperature at T→0 K has been estimated (Θ0 = 84.4 K). In the interval from 1.2 to 30 K the experimental curve of the heat capacity of C60 describes the contributions of rotational tunnel levels, translational vibrations (in the Debye model with Θ0 = 84.4 K), and librations (in the Einstein model with ΘE,lib = 32.5 K). It is shown that the experimental temperature dependences of heat capacity and thermal expansion are proportional in the region from 5 to 60 K. The contribution of the cooperative processes of orientational disordering becomes appreciable above 180 K. In the high-temperature phase the lattice heat capacity at constant volume is close to 4.5 R, which corresponds to the high-temperature limit of translational vibrations (3 R) and the near-free rotational motion of C60 molecules (1.5 R).
Conducted noise analysis and protection of 45 kJ/s, ±50 kV capacitor charging power supply when interfaced with repetitive Marx based pulse power system
Authors: Naresh P. , Patel Ankur , Sharma Archana
Published: September 2015

Pulse power systems with highly dynamic loads like klystron, backward wave oscillator (BWO), and magnetron generate highly dynamic noise. This noise leads to frequent failure of controlled switches in the inverter stage of charging power supply. Designing a reliable and compatible power supply for pulse power applications is always a tricky job when charging rate is in multiples of 10 kJ/s. A ±50 kV and 45 kJ/s capacitor charging power supply based on 4th order LCLC resonant topology has been developed for a 10 Hz repetitive Marx based system. Conditions for load independent constant current and zero current switching (ZCS) are derived mathematically. Noise generated at load end due to dynamic load is tackled effectively and reduction in magnitude noise voltage is achieved by providing shielding between primary and secondary of high voltage high frequency transformer and with LCLC low pass filter. Shielding scales down the ratio between coupling capacitance (Cc) and the collector-emitter capacitance of insulated gate bi-polar transistor switch, which in turn reduces the common mode noise voltage magnitude. The proposed 4th order LCLC resonant network acts as a low pass filter for differential mode noise in the reverse direction (from load to source). Power supply has been tested repeatedly with 5 Hz repetition rate with repetitive Marx based system connected with BWO load working fine without failure of single switch in the inverter stage.
A hybrid electron cyclotron resonance metal ion source with integrated sputter magnetron for the production of an intense Al+ ion beam
Authors: Weichsel T. , Hartung U. , Kopte T. , Zschornack G. , Kreller M. , Philipp A.
Published: September 2015

A metal ion source prototype has been developed: a combination of magnetron sputter technology with 2.45 GHz electron cyclotron resonance (ECR) ion source technology—a so called magnetron ECR ion source (MECRIS). An integrated ring-shaped sputter magnetron with an Al target is acting as a powerful metal atom supply in order to produce an intense current of singly charged metal ions. Preliminary experiments show that an Al+ ion current with a density of 167 μA/cm2 is extracted from the source at an acceleration voltage of 27 kV. Spatially resolved double Langmuir probe measurements and optical emission spectroscopy were used to study the plasma states of the ion source: sputter magnetron, ECR, and MECRIS plasma. Electron density and temperature as well as Al atom density were determined as a function of microwave and sputter magnetron power. The effect of ECR heating is strongly pronounced in the center of the source. There the electron density is increased by one order of magnitude from 6 × 109 cm−3 to 6 × 1010 cm−3 and the electron temperature is enhanced from about 5 eV to 12 eV, when the ECR plasma is ignited to the magnetron plasma. Operating the magnetron at constant power, it was observed that its discharge current is raised from 1.8 A to 4.8 A, when the ECR discharge was superimposed with a microwave power of 2 kW. At the same time, the discharge voltage decreased from about 560 V to 210 V, clearly indicating a higher plasma density of the MECRIS mode. The optical emission spectrum of the MECRIS plasma is dominated by lines of excited Al atoms and shows a significant contribution of lines arising from singly ionized Al. Plasma emission photography with a CCD camera was used to prove probe measurements and to identify separated plasma emission zones originating from the ECR and magnetron discharge.
Enzyme localization, crowding, and buffers collectively modulate diffusion-influenced signal transduction: Insights from continuum diffusion modeling
Authors: Kekenes-Huskey Peter M. , Eun Changsun , McCammon J. A.
Published: September 2015

Biochemical reaction networks consisting of coupled enzymes connect substrate signaling events with biological function. Substrates involved in these reactions can be strongly influenced by diffusion “barriers” arising from impenetrable cellular structures and macromolecules, as well as interactions with biomolecules, especially within crowded environments. For diffusion-influenced reactions, the spatial organization of diffusion barriers arising from intracellular structures, non-specific crowders, and specific-binders (buffers) strongly controls the temporal and spatial reaction kinetics. In this study, we use two prototypical biochemical reactions, a Goodwin oscillator, and a reaction with a periodic source/sink term to examine how a diffusion barrier that partitions substrates controls reaction behavior. Namely, we examine how conditions representative of a densely packed cytosol, including reduced accessible volume fraction, non-specific interactions, and buffers, impede diffusion over nanometer length-scales. We find that diffusion barriers can modulate the frequencies and amplitudes of coupled diffusion-influenced reaction networks, as well as give rise to “compartments” of decoupled reactant populations. These effects appear to be intensified in the presence of buffers localized to the diffusion barrier. These findings have strong implications for the role of the cellular environment in tuning the dynamics of signaling pathways.
A polarized digital shearing speckle pattern interferometry system based on temporal wavelet transformation
Authors: Feng Ziang , Gao Zhan , Zhang Xiaoqiong , Wang Shengjia , Yang Dong , Yuan Hao , Qin Jie
Published: September 2015

Digital shearing speckle pattern interferometry (DSSPI) has been recognized as a practical tool in testing strain. The DSSPI system which is based on temporal analysis is attractive because of its ability to measure strain dynamically. In this paper, such a DSSPI system with Wollaston prism has been built. The principles and system arrangement are described and the preliminary experimental result of the displacement-derivative test of an aluminum plate is shown with the wavelet transformation method and the Fourier transformation method. The simulations have been conducted with the finite element method. The comparison of the results shows that quantitative measurement of displacement-derivative has been realized.
Entropic (de)stabilization of surface-bound peptides conjugated with polymers
Authors: Carmichael Scott P. , Shell M. Scott
Published: September 2015

In many emerging biotechnologies, functional proteins must maintain their native structures on or near interfaces (e.g., tethered peptide arrays, protein coated nanoparticles, and amphiphilic peptide micelles). Because the presence of a surface is known to dramatically alter the thermostability of tethered proteins, strategies to stabilize surface-bound proteins are highly sought. Here, we show that polymer conjugation allows for significant control over the secondary structure and thermostability of a model surface-tethered peptide. We use molecular dynamics simulations to examine the folding behavior of a coarse-grained helical peptide that is conjugated to polymers of various lengths and at various conjugation sites. These polymer variations reveal surprisingly diverse behavior, with some stabilizing and some destabilizing the native helical fold. We show that ideal-chain polymer entropies explain these varied effects and can quantitatively predict shifts in folding temperature. We then develop a generic theoretical model, based on ideal-chain entropies, that predicts critical lengths for conjugated polymers to effect changes in the folding of a surface-bound protein. These results may inform new design strategies for the stabilization of surface-associated proteins important for a range technological applications.
Computer simulation of critical behavior in spin models with nonmagnetic impurities
Authors: Babaev A. B. , Murtazaev A. K.
Published: September 2015

The results of computer simulations of the critical behavior of three-dimensional structures described by disordered Potts models with q = 3 and q = 4 spin states are discussed. Systems with linear dimensions L = 20–60 with spin concentrations p = 1.00, 0.95, 0.90, 0.80, 0.70, and 0.65 are examined. It is found that in a three-dimensional Potts model with q = 3 spin states, introducing nonmagnetic impurities induces a second order phase transition. In a Potts model with q = 4, on the other hand, a shift from a first order phase transition to a second order phase transition is observed at high dilution (p = 0.65). Numerical values of the critical parameters are found using finite-size scaling theory and it is shown that they form a universality class corresponding to disordered systems.
Non-equilibrium phase transitions in a liquid crystal
Authors: Dan K. , Roy M. , Datta A.
Published: September 2015

The present manuscript describes kinetic behaviour of the glass transition and non-equilibrium features of the “Nematic-Isotropic” (N-I) phase transition of a well known liquid crystalline material N-(4-methoxybenzylidene)-4-butylaniline from the effects of heating rate and initial temperature on the transitions, through differential scanning calorimetry (DSC), Fourier transform infrared and fluorescence spectroscopy. Around the vicinity of the glass transition temperature (Tg), while only a change in the baseline of the ΔCp vs T curve is observed for heating rate (β) > 5 K min−1, consistent with a glass transition, a clear peak for β ≤ 5 K min−1 and the rapid reduction in the ΔCp value from the former to the latter rate correspond to an order-disorder transition and a transition from ergodic to non-ergodic behaviour. The ln β vs 1000/T curve for the glass transition shows convex Arrhenius behaviour that can be explained very well by a purely entropic activation barrier [Dan et al., Eur. Phys. Lett. 108, 36007 (2014)]. Fourier transform infrared spectroscopy indicates sudden freezing of the out-of-plane distortion vibrations of the benzene rings around the glass transition temperature and a considerable red shift indicating enhanced coplanarity of the benzene rings and, consequently, enhancement in the molecular ordering compared to room temperature. We further provide a direct experimental evidence of the non-equilibrium nature of the N-I transition through the dependence of this transition temperature (TNI) and associated enthalpy change (ΔH) on the initial temperature (at fixed β-values) for the DSC scans. A plausible qualitative explanation based on Mesquita’s extension of Landau-deGennes theory [O. N. de Mesquita, Braz. J. Phys. 28, 257 (1998)] has been put forward. The change in the molecular ordering from nematic to isotropic phase has been investigated through fluorescence anisotropy measurements where the order parameter, quantified by the anisotropy, goes to zero from nematic to isotropic phase. To a point below the transition temperature, the order parameter is constant but decreases linearly with increase in temperature below that indicating the dependence of nematic ordering on the initial temperature during heating consistent with the non-equilibrium nature of nematic-isotropic phase transition.
High performance surface plasmon sensors: Simulations and measurements
Authors: Tiwari Kunal , Sharma Suresh C. , Hozhabri Nader
Published: September 2015

Through computer simulations and surface plasmon resonance (SPR) measurements, we establish optimum parameters for the design and fabrication of SPR sensors of high sensitivity, resolution, stability, and long decay-length evanescent fields. We present simulations and experimental SPR data for variety of sensors fabricated by using bimetal (Ag/Au) and multilayer waveguide-coupled Ag/Si3N4/Au structures. The simulations were carried out by using the transfer matrix method in MATLAB environment. Results are presented as functions of the thickness of the metal (Ag or Au) and the waveguide dielectric used in Ag/Si3N4/Au structures. Excellent agreement is observed between the simulations and experiments. For optimized thickness of the Si3N4 waveguide (150 nm), the sensor exhibits very high sensitivity to changes in the refractive index of analytes, Sn≈52°/RIU, extremely high resolution (FWHM≤0.28°), and long penetration depth of evanescent fields (δ≥305nm).
Elastic and piezoelectric moduli of Nd and Sm ferroborates
Authors: Gaydamak T. N. , Gudim I. A. , Zvyagina G. A. , Bilych I. V. , Burma N. G. , Zhekov K. R. , Fil V. D.
Published: September 2015

The sound speeds are measured and the elastic and piezoelectric moduli are calculated for single crystal NdFe3(BO3)4 and SmFe3(BO3)4. These compounds are characterized by enhanced rigidity in the base plane with respect to stress-strain deformations and by a rather strong piezoelectric effect.
Nuclear spin noise in NMR revisited
Authors: Ferrand Guillaume , Huber Gaspard , Luong Michel , Desvaux Hervé
Published: September 2015

The theoretical shapes of nuclear spin-noise spectra in NMR are derived by considering a receiver circuit with finite preamplifier input impedance and a transmission line between the preamplifier and the probe. Using this model, it becomes possible to reproduce all observed experimental features: variation of the NMR resonance linewidth as a function of the transmission line phase, nuclear spin-noise signals appearing as a “bump” or as a “dip” superimposed on the average electronic noise level even for a spin system and probe at the same temperature, pure in-phase Lorentzian spin-noise signals exhibiting non-vanishing frequency shifts. Extensive comparisons to experimental measurements validate the model predictions, and define the conditions for obtaining pure in-phase Lorentzian-shape nuclear spin noise with a vanishing frequency shift, in other words, the conditions for simultaneously obtaining the spin-noise and frequency-shift tuning optima.
Radio frequency reflectometry and charge sensing of a precision placed donor in silicon
Authors: Hile Samuel J. , House Matthew G. , Peretz Eldad , Verduijn Jan , Widmann Daniel , Kobayashi Takashi , Rogge Sven , Simmons Michelle Y.
Published: September 2015

We compare charge transitions on a deterministic single P donor in silicon using radio frequency reflectometry measurements with a tunnel coupled reservoir and DC charge sensing using a capacitively coupled single electron transistor (SET). By measuring the conductance through the SET and comparing this with the phase shift of the reflected radio frequency (RF) excitation from the reservoir, we can discriminate between charge transfer within the SET channel and tunneling between the donor and reservoir. The RF measurement allows observation of donor electron transitions at every charge degeneracy point in contrast to the SET conductance signal where charge transitions are only observed at triple points. The tunnel coupled reservoir has the advantage of a large effective lever arm (∼35%), allowing us to independently extract a neutral donor charging energy ∼62 ± 17 meV. These results demonstrate that we can replace three terminal transistors by a single terminal dispersive reservoir, promising for high bandwidth scalable donor control and readout.
Development of a stereo-symmetrical nanosecond pulsed power generator composed of modularized avalanche transistor Marx circuits
Authors: Li Jiang-Tao , Zhong Xu , Cao Hui , Zhao Zheng , Xue Jing , Li Tao , Li Zheng , Wang Ya-Nan
Published: September 2015

Avalanche transistors have been widely studied and used in nanosecond high voltage pulse generations. However, output power improvement is always limited by the low thermal capacities of avalanche transistors, especially under high repetitive working frequency. Parallel stacked transistors can effectively improve the output current but the controlling of trigger and output synchronism has always been a hard and complex work. In this paper, a novel stereo-symmetrical nanosecond pulsed power generator with high reliability was developed. By analyzing and testing the special performances of the combined Marx circuits, numbers of meaningful conclusions on the pulse amplitude, pulse back edge, and output impedance were drawn. The combining synchronism of the generator was confirmed excellent and lower conducting current through the transistors was realized. Experimental results showed that, on a 50 Ω resistive load, pulses with 1.5–5.2 kV amplitude and 5.3–14.0 ns width could be flexibly generated by adjusting the number of combined modules, the supply voltage, and the module type.
Flow of DNA solutions in a microfluidic gradual contraction
Authors: Gulati Shelly , Muller Susan J. , Liepmann Dorian
Published: September 2015

The flow of λ-DNA solutions in a gradual micro-contraction was investigated using direct measurement techniques. The effects on DNA transport in microscale flows are significant because the flow behavior is influenced by macromolecular conformations, both viscous and elastic forces dominate inertial forces at this length scale, and the fully extended length of the molecule approaches the characteristic channel length wc (L/wc ∼ 0.13). This study examines the flow of semi-dilute and entangled DNA solutions in a gradual planar micro-contraction for low Reynolds numbers (3.7 × 10−6 < Re < 3.1 × 10−1) and high Weissenberg numbers (0.4 < Wi < 446). The semi-dilute DNA solutions have modest elasticity number, El = Wi/Re = 55, and do not exhibit viscoelastic behavior. For the entangled DNA solutions, we access high elasticity numbers (7.9 × 103 < El < 6.0 × 105). Video microscopy and streak images of entangled DNA solution flow reveal highly elastic behavior evidenced by the presence of large, stable vortices symmetric about the centerline and upstream of the channel entrance. Micro-particle image velocimetry measurements are used to obtain high resolution, quantitative velocity measurements of the vortex growth in this micro-contraction flow. These direct measurements provide a deeper understanding of the underlying physics of macromolecular transport in microfluidic flow, which will enable the realization of enhanced designs of lab-on-a-chip systems.
Demonstration of a III-nitride vertical-cavity surface-emitting laser with a III-nitride tunnel junction intracavity contact
Authors: Leonard J. T. , Young E. C. , Yonkee B. P. , Cohen D. A. , Margalith T. , DenBaars S. P. , Speck J. S. , Nakamura S.
Published: September 2015

We report on a III-nitride vertical-cavity surface-emitting laser (VCSEL) with a III-nitride tunnel junction (TJ) intracavity contact. The violet nonpolar VCSEL employing the TJ is compared to an equivalent VCSEL with a tin-doped indium oxide (ITO) intracavity contact. The TJ VCSEL shows a threshold current density (Jth) of ∼3.5 kA/cm2, compared to the ITO VCSEL Jth of 8 kA/cm2. The differential efficiency of the TJ VCSEL is also observed to be significantly higher than that of the ITO VCSEL, reaching a peak power of ∼550 μW, compared to ∼80 μW for the ITO VCSEL. Both VCSELs display filamentary lasing in the current aperture, which we believe to be predominantly a result of local variations in contact resistance, which may induce local variations in refractive index and free carrier absorption. Beyond the analyses of the lasing characteristics, we discuss the molecular-beam epitaxy (MBE) regrowth of the TJ, as well as its unexpected performance based on band-diagram simulations. Furthermore, we investigate the intrinsic advantages of using a TJ intracavity contact in a VCSEL using a 1D mode profile analysis to approximate the threshold modal gain and general loss contributions in the TJ and ITO VCSEL.
Suppressing sub-bandgap phonon-polariton heat transfer in near-field thermophotovoltaic devices for waste heat recovery
Authors: Chen Kaifeng , Santhanam Parthiban , Fan Shanhui
Published: September 2015

We consider a near-field thermophotovoltaic device with metal as the emitter and semiconductor as the photovoltaic cell. We show that when the cell is a III-V semiconductor, such as GaSb, parasitic phonon-polariton heat transfer reduces efficiency in the near-field regime, especially when the temperature of the emitter is not high enough. We further propose ways to avoid the phonon-polariton heat transfer by replacing the III-V semiconductor with a non-polar semiconductor such as Ge. Our work provides practical guidance on the design of near-field thermophotovoltaic systems for efficient harvesting of low-quality waste heat.
Interface Fe magnetic moment enhancement in MgO/Fe/MgO trilayers
Authors: Jal Emmanuelle , Kortright Jeffrey B. , Chase Tyler , Liu TianMin , Gray Alexander X. , Shafer Padraic , Arenholz Elke , Xu Pengfa , Jeong Jaewoo , Samant Mahesh G. , Parkin Stuart S. P. , Dürr Hermann A.
Published: September 2015

We model room temperature soft x-ray resonant magnetic reflectivity to determine a 24% increase of the Fe magnetic moment of the 2–3 monolayers next to both MgO interfaces in a MgO(3 nm)/Fe(12 nm)/MgO(001) heterostructure. This direct measurement of such enhanced interface magnetic moments for buried interfaces confirms theoretical predictions and highlights the importance of considering inhomogeneous in-depth magnetic profile in Fe/MgO based magnetic tunnel junctions.
Temperature-dependent dielectric functions in atomically thin graphene, silicene, and arsenene
Authors: Yang J. Y. , Liu L. H.
Published: September 2015

The dielectric functions of atomically thin graphene, silicene, and arsenene have been investigated as a function of temperature. With zero energy gap, more carriers in graphene and silicene are thermally excited as temperature increases and intraband transition strengthens, resulting in the strengthened absorption peak. Yet with large energy gap, interband transition dominates optical absorption of arsenene but it reduces as lattice vibration enhances, inducing the redshift and decreased absorption peak. To validate the theoretical method, the calculated optical constants of isolated graphene are compared with ellipsometry results and demonstrate good agreement.
Charge neutrality levels, barrier heights, and band offsets at polar AlGaN
Authors: Reddy Pramod , Bryan Isaac , Bryan Zachary , Tweedie James , Washiyama Shun , Kirste Ronny , Mita Seiji , Collazo Ramon , Sitar Zlatko
Published: September 2015

In this work, the Fermi level and band alignment at c-plane surfaces and interfaces of AlGaN thin films grown on sapphire and native single crystalline AlN substrates were analyzed via x-ray photoelectron spectroscopy. The dependence of charge neutrality level (CNL) on Al composition is found to be linear with n-type Schottky barrier heights (Φbn) exhibiting an overall quadratic behavior due to bandgap bowing. A general theoretical expression for Schottky barrier height on AlGaN is determined as a function of Al composition and metal electronegativity utilizing the interface induced gap states (IFIGS) model and is corroborated with current-voltage (I-V) characterization on Ni-based Schottky diodes. The measured CNLs were used to determine the conduction and valence band offsets in AlGaN hetero-junctions according to the IFIGS and were found to be split approximately 2/3 and 1/3 of the bandgap, respectively, at interfaces with AlGaN having comparable Al and Ga concentrations. Nonlinearities in Φbn result in an increase (>2/3) and decrease (<2/3) of the conduction band split at AlN/AlGaN and GaN/AlGaN interfaces, respectively. Characterization of core level binding energies revealed a composition-independent surface work function. Consequently, electron affinity is found to be a linear function of the barrier height at the CNL and band offsets determined via IFIGS and Anderson's rule were found to be identical. The origin of the bandgap bowing arising in the conduction band is proposed.
Submicron mass spectrometry imaging of single cells by combined use of mega electron volt time-of-flight secondary ion mass spectrometry and scanning transmission ion microscopy
Authors: Siketić Zdravko , Bogdanović Radović Ivančica , Jakšić Milko , Popović Hadžija Marijana , Hadžija Mirko
Published: September 2015

In order to better understand biochemical processes inside an individual cell, it is important to measure the molecular composition at the submicron level. One of the promising mass spectrometry imaging techniques that may be used to accomplish this is Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), using MeV energy heavy ions for excitation. MeV ions have the ability to desorb large intact molecules with a yield that is several orders of magnitude higher than conventional SIMS using keV ions. In order to increase the spatial resolution of the MeV TOF-SIMS system, we propose an independent TOF trigger using a STIM (scanning transmission ion microscopy) detector that is placed just behind the thin transmission target. This arrangement is suitable for biological samples in which the STIM detector simultaneously measures the mass distribution in scanned samples. The capability of the MeV TOF-SIMS setup was demonstrated by imaging the chemical composition of CaCo-2 cells.
Damage free integration of ultralow-k dielectrics by template replacement approach
Authors: Zhang L. , de Marneffe J.-F. , Heylen N. , Murdoch G. , Tokei Z. , Boemmels J. , De Gendt S. , Baklanov M. R.
Published: September 2015

Cu/low-k integration by conventional damascene approach is becoming increasingly difficult as critical dimensions scale down. An alternative integration scheme is studied based on the replacement of a sacrificial template by ultralow-k dielectric. A metal structure is first formed by patterning a template material. After template removal, a k = 2.31 spin-on type of porous low-k dielectric is deposited onto the patterned metal lines. The chemical and electrical properties of spin-on dielectrics are studied on blanket wafers, indicating that during hard bake, most porogen is removed within few minutes, but 120 min are required to achieve the lowest k-value. The effective dielectric constant of the gap-fill low-k is investigated on a 45 nm ½ pitch Meander-Fork structure, leading to keff below 2.4. The proposed approach solves the two major challenges in conventional Cu/low-k damascene integration approach: low-k plasma damage and metal penetration during barrier deposition on porous materials.
Sulfur doping of M/In2O3 (M=Al,W) nanowires with room temperature near infra red emission
Authors: Zervos M. , Mihailescu C. , Giapintzakis J. , Othonos A. , Travlos A.
Published: September 2015

We have investigated the growth of Al doped In2O3 nanowires via the vapor-liquid-solid mechanism at 800°C using Au as a catalyst. We find that the Al is not incorporated into the cubic bixbyite crystal structure of In2O3 but nevertheless was detected in the form of Al2O3. The nanowires had metallic like conductivities and exhibited photoluminescence at 2.3 eV which shifted to 1.5 eV after exposure to H2S above 500°C due to the formation of β-In2S3 and deep donor to acceptor transitions with a lifetime of ≈1 μs. The near infra red emission was also observed in W/In2O3 but not in W/SnO2 core-shell nanowires after processing under H2S at 600°C, confirming it is related to β-In2S3. The nanowires remain one dimensional up to 900°C due to the shell which is interesting for the fabrication of high temperature nanowire sensors.