bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanophotonic detection of freely interacting molecules on a single influenza virus
Authors: Kang Pilgyu , Schein Perry , Serey Xavier , O’Dell Dakota , Erickson David
Published: July 2015

Biomolecular interactions, such as antibody-antigen binding, are fundamental to many biological processes. At present, most techniques for analyzing these interactions require immobilizing one or both of the interacting molecules on an assay plate or a sensor surface. This is convenient experimentally but can constrain the natural binding affinity and capacity of the molecules, resulting in data that can deviate from the natural free-solution behavior. Here we demonstrate a label-free method for analyzing free-solution interactions between a single influenza virus and specific antibodies at the single particle level using near-field optical trapping and light-scattering techniques. We determine the number of specific antibodies binding to an optically trapped influenza virus by analyzing the change of the Brownian fluctuations of the virus. We develop an analytical model that determines the increased size of the virus resulting from antibodies binding to the virus membrane with uncertainty of ±1–2 nm. We present stoichiometric results of 26 ± 4 (6.8 ± 1.1 attogram) anti-influenza antibodies binding to an H1N1 influenza virus. Our technique can be applied to a wide range of molecular interactions because the nanophotonic tweezer can handle molecules from tens to thousands of nanometers in diameter.
Controlling the on/off current ratio of ferroelectric field-effect transistors
Authors: Katsouras Ilias , Zhao Dong , Spijkman Mark-Jan , Li Mengyuan , Blom Paul W. M. , Leeuw Dago M. de , Asadi Kamal
Published: July 2015

The on/off current ratio in organic ferroelectric field-effect transistors (FeFETs) is largely determined by the position of the threshold voltage, the value of which can show large device-to-device variations. Here we show that by employing a dual-gate layout for the FeFET, we can gain full control over the on/off ratio. In the resulting dual-gate FeFET the ferroelectric gate provides the memory functionality and the second, non-ferroelectric, control gate is advantageously used to set the threshold voltage. The on/off ratio can thus be maximized at the readout bias. The operation is explained by the quantitative analysis of charge transport in a dual-gate FeFET.
Centrifugation-assisted Assembly of Colloidal Silica into Crack-Free and Transferrable Films with Tunable Crystalline Structures
Authors: Fan Wen , Chen Min , Yang Shu , Wu Limin
Published: July 2015

Self-assembly of colloidal particles into colloidal films has many actual and potential applications. While various strategies have been developed to direct the assembly of colloidal particles, fabrication of crack-free and transferrable colloidal film with controllable crystal structures still remains a major challenge. Here we show a centrifugation-assisted assembly of colloidal silica spheres into free-standing colloidal film by using the liquid/liquid interfaces of three immiscible phases. Through independent control of centrifugal force and interparticle electrostatic repulsion, polycrystalline, single-crystalline and quasi-amorphous structures can be readily obtained. More importantly, by dehydration of silica particles during centrifugation, the spontaneous formation of capillary water bridges between particles enables the binding and pre-shrinkage of the assembled array at the fluid interface. Thus the assembled colloidal films are not only crack-free, but also robust and flexible enough to be easily transferred on various planar and curved substrates.
Assessing the Efficacy of Mdm2/Mdm4-Inhibiting Stapled Peptides Using Cellular Thermal Shift Assays
Authors: Tan Ban Xiong , Brown Christopher J. , Ferrer Fernando J. , Yuen Tsz Ying , Quah Soo Tng , Chan Boon Hong , Jansson Anna E. , Teo Hsiang Ling , Nordlund Pär , Lane David P.
Published: July 2015

Previous publications on stapled peptide inhibitors against Mdm2/Mdm4-p53 interactions have established that this new class of drugs have the potential to be easily optimised to attain high binding affinity and specificity, but the mechanisms controlling their cellular uptake and target engagement remain elusive and controversial. To aid in understanding the rules of peptide and staple design and to enable rapid optimisation, we employed the newly-developed cellular thermal shift assay (CETSA). CETSA was able to validate stapled peptide binding to Mdm2 and Mdm4 and the method was also used to determine the extent of cellular uptake, cellular availability and intracellular binding of the endogenous target proteins in its native environment. Our data suggest that while the stapled peptides engage their targets intracellularly, more work is needed to improve their cellular entry and target engagement efficiency in vivo. CETSA now provides a valuable tool to optimize such in vivo properties of stapled peptides.
Porphyrin-loaded liposomes and graphene oxide used for the membrane pore-forming protein assay and inhibitor screening
Authors: Liu Zhongde , Long Tengfei , Wu Shuang , Li Chong
Published: July 2015

A strategy for membrane pore-forming protein assay and inhibitor screening was developed with the combination of TAPP-loaded liposomes and GO sheets.
A local collision probability approximation for predicting momentum transfer cross sections
Authors: Bleiholder Christian
Published: July 2015

The local collision probability approximation (LCPA) method is introduced to compute molecular momentum transfer cross sections for comparison to ion mobility experiments.
Reconstructing accurate ToF-SIMS depth profiles for organic materials with differential sputter rates
Authors: Taylor Adam J. , Graham Daniel J. , Castner David G.
Published: July 2015

This study describes new methods to transform and correct ToF-SIMS depth profiles of multilayer polymer films exhibiting differential sputter rates.
Electrochemical analysis of a novel ferrocene derivative as a potential antitumor drug
Authors: Bartošík M. , Koubková L. , Karban J. , Červenková Šťastná L. , Hodík T. , Lamač M. , Pinkas J. , Hrstka R.
Published: July 2015

Ferrocenes represent an interesting group of drugs with potential antitumor properties.
A label-free cyclic assembly of G-quadruplex nanowires for cascade amplification detection of T4 polynucleotide kinase activity and inhibition
Authors: Shi Zhilu , Zhang Xiafei , Cheng Rui , Li Baoxin , Jin Yan
Published: July 2015

A label-free and enzyme-free amplification strategy has been developed for sensitively and specifically studying PNK activity and inhibitionviathe hybridization chain reaction (HCR).
Optical detection enhancement in porous volumetric microfluidic capture elements using refractive index matching fluids
Authors: Wiederoder M. S. , Peterken L. , Lu A. X. , Rahmanian O. D. , Raghavan S. R. , DeVoe D. L.
Published: July 2015

Optical index matching fluids enable porous volumetric capture elements in microfluidic systems to take advantage of higher reaction site density and decreased diffusion lengths, enhancing detection limits and throughput compared with planar capture surfaces.
A new electrochemical substrate for rapid and sensitive in vivo monitoring of β-galactosidase gene expressions
Authors: Manibalan Kesavan , Mani Veerappan , Huang Chih-Hung , Huang Sheng-Tung , Chang Pu-Chieh
Published: July 2015

An electrochemical assay platform based on 4-MPGal for the monitoring of β-galactosidase expressions.
Highly sensitive detection of sequence-specific DNA with morpholino-functionalized magnetic microspheres
Authors: Hu Weiwen , Ning Yong , Li Lianzhi , Kong Jinming , Zhang Xueji
Published: July 2015

In this work, a highly effective biosensor supported on morpholino-functionalized magnetic microspheres was investigated for the sequence-specific detection of DNA.
Applications of yttria stabilized zirconia (YSZ) in catalysis
Authors: Tsampas M. N. , Sapountzi F. M. , Vernoux P.
Published: July 2015

The main applications of yttria stabilized zirconia in catalysis are briefly reviewed and analyzed based on its functionalities.
A biodiesel additive: etherification of 5-hydroxymethylfurfural with isobutene to tert-butoxymethylfurfural
Authors: Yang Feifei , Zhang Shuguang , Zhang Z. Conrad , Mao Jingbo , Li Shenmin , Yin Jingmei , Zhou Jinxia
Published: July 2015

Etherification of 5-hydroxymethylfurfural with isobutene on acid catalysts is systematically studied to synthesise the attractive biodiesel additive, tert-butoxymethylfurfural (tBMF).
Magnetically retrievable magnetite (Fe3O4) immobilized ionic liquid: an efficient catalyst for the preparation of 1-carbamatoalkyl-2-naphthols
Authors: Dadhania Harsh N. , Raval Dipak K. , Dadhania Abhishek N.
Published: July 2015

An efficient and greener protocol for the synthesis of 1-carbamatoalkyl-2-naphthols using magnetically retrievable ionic liquid.
Single molecule fluorescence resonance energy transfer scanning near-field optical microscopy: potentials and challenges
Authors: Sekatskii S. K. , Dukenbayev K. , Mensi M. , Mikhaylov A. G. , Rostova E. , Smirnov A. , Suriyamurthy N. , Dietler G.
Published: July 2015

A few years ago, single molecule Fluorescence Resonance Energy Transfer Scanning Near-Field Optical Microscope (FRET SNOM) images were demonstrated using CdSe semiconductor nanocrystal–dye molecules as donor–acceptor pairs. Corresponding experiments reveal the necessity to exploit much more photostable fluorescent centers for such an imaging technique to become a practically used tool. Here we report the results of our experiments attempting to use nitrogen vacancy (NV) color centers in nanodiamond (ND) crystals, which are claimed to be extremely photostable, for FRET SNOM. All attempts were unsuccessful, and as a plausible explanation we propose the absence (instability) of NV centers lying close enough to the ND border. We also report improvements in SNOM construction that are necessary for single molecule FRET SNOM imaging. In particular, we present the first topographical images of single strand DNA molecules obtained with fiber-based SNOM. The prospects of using rare earth ions in crystals, which are known to be extremely photostable, for single molecule FRET SNOM at room temperature and quantum informatics at liquid helium temperatures, where FRET is a coherent process, are also discussed.
Modulation of tissue fatty acids byl-carnitine attenuates metabolic syndrome in diet-induced obese rats
Authors: Panchal Sunil K. , Poudyal Hemant , Ward Leigh C. , Waanders Jennifer , Brown Lindsay
Published: July 2015

l-Carnitine induced preferential oxidation of linoleic acid (C18:2n-6) in liver, skeletal muscle and retroperitoneal fat, increased stored oleic acid (C18:1n-9) in liver and skeletal muscle whiletrans-vaccenic acid (C18:1trans-11) was increased in retroperitoneal fat.
Effects of anthocyanins from purple sweet potato (Ipomoea batatas L. cultivar Eshu No. 8) on the serum uric acid level and xanthine oxidase activity in hyperuricemic mice
Authors: Zhang Zi-Cheng , Su Guan-Hua , Luo Chun-Li , Pang Ya-Lu , Wang Lin , Li Xing , Wen Jia-Hao , Zhang Jiu-Liang
Published: July 2015

This study was aimed at evaluating the hypouricemic effect of the anthocyanin-rich purple sweet potato extract (APSPE).
Pomegranate extract induces ellagitannin metabolite formation and changes stool microbiota in healthy volunteers
Authors: Li Zhaoping , Henning Susanne M. , Lee Ru-Po , Lu Qing-Yi , Summanen Paula H. , Thames Gail , Corbett Karen , Downes Julia , Tseng Chi-Hong , Finegold Sydney M. , Heber David
Published: July 2015

The health benefits of pomegranate (POM) consumption are attributed to ellagitannins and their metabolites, formed and absorbed in the intestine by the microbiota.
Highly trans-1,4-stereoselective coordination chain transfer polymerization of 1,3-butadiene and copolymerization with cyclic esters by a neodymium-based catalyst system
Authors: Zheng Wenjie , Yan Nan , Zhu Yutian , Zhao Wenpeng , Zhang Chunyu , Zhang Hexin , Bai Chenxi , Hu Yanming , Zhang Xuequan
Published: July 2015

Highly trans-1,4-stereoregular polybutadiene (TPB) was obtained by CCTP and novel amphiphilic copolymers (TPB-b-PCL/PLA) were successfully synthesized.
Validating potential energy surfaces for classical trajectory calculations
Authors: Pritchard Huw O.
Published: July 2015

Potential energy distributions for normal and reacting molecules.
Nitrogen-rich salts of 1-aminotetrazol-5-one: oxygen-containing insensitive energetic materials with high thermal stability
Authors: Yin Xin , Wu Jin-Ting , Jin Xin , Xu Cai-Xia , He Piao , Li Tong , Wang Kun , Qin Jian , Zhang Jian-Guo
Published: July 2015

Energetic ionic salts based on ATO exhibit a good balance between low sensitivity and high detonation performance.
Plasma-assisted multi-layered coating towards improved gas permeation properties for organosilica membranes
Authors: Ren Xiuxiu , Kanezashi Masakoto , Nagasawa Hiroki , Tsuru Toshinori
Published: July 2015

Plasma treatment enhanced separation performance of multi-layered membranes consisting of a hydrophobic top-layer and hydrophobic intermediate-layer.
A surfactant free synthesis and formation mechanism of hollow Cu2O nanocubes using Cl− ions as the morphology regulator
Authors: Wang Qiuxiang , kuang Qin , Wang Kunshui , Wang Xue , Xie Zhaoxiong
Published: July 2015

Hollow Cu2O nanocubes were prepared via a surfactant-free route where the CuCl intermediates formed with Cl− ions acted as self-sacrificial template.
The enhanced electrocaloric effect in P(VDF-TrFE) copolymer with barium strontium titanate nano-fillers synthesized via an effective hydrothermal method
Authors: Jiang Z. Y. , Zheng X. C. , Zheng G. P.
Published: July 2015

An effective hydrothermal method is developed to synthesize barium strontium titanate nanoparticles with a mean size below 30 nm, which are used for the fabrication of nanocomposite films consisting of P(VDF-TrFE) and ceramic nanoparticles.
Novel architecture for anomalous strengthening of a particulate filled polymer matrix composite
Authors: Reddy Siva Kumar , Lal Devi , Misra Abha , Kumar Praveen
Published: July 2015

We propose an architecture for dramatically enhancing the stress bearing and energy absorption capacities of a polymer based composite.
Preparation of SnO2/graphene nanocomposite and its application to the catalytic epoxidation of alkenes with H2O2
Authors: Liu Min , Wang Xiaozhong , Chen Yingqi , Dai Liyan
Published: July 2015

The SnO2/graphene nanocomposites have been achieved via hydrothermal method and used as an efficient catalyst for the epoxidation of alkenes with H2O2 in nitrile based systems for the first time.
Tunable catalytic reactivity of small palladium clusters supported on graphene: a first-principles study
Authors: Xiao W. , Zeng R. , Cheng L. , Wang J. W. , Jiang L. J. , Wang L. G.
Published: July 2015

The catalytic reactivity is controlled by the binding strength between the catalyst surface and reaction intermediates.
Improving the tribological properties of NiAl matrix composites via hybrid lubricants of silver and graphene nano platelets
Authors: Ibrahim Ahmed Mohamed Mahmoud , Shi Xiaoliang , Zhai Wenzheng , Yang Kang
Published: July 2015

This work presents a comprehensive study of the synergistic tribological effect of combined solid lubricants of silver and graphene nano platelets (GNPs).
Photocatalytic degradation of methylene blue with hematite nanoparticles synthesized by thermal decomposition of fluoroquinolones oxalato–iron(iii) complexes
Authors: Mansour Ahmed M.
Published: July 2015

Thermal decomposition of fluoroquinolones oxalato iron(iii) complexes, synthesized from fluoroquinolones and potassium tris(oxalato)ferrate(iii) trihydrate, gave α-Fe2O3 nanoparticles suitable for the photocatalytic degradation of methylene blue.
A mild CuBr–NMO oxidative system for the coupling of anilines leading to aromatic azo compounds
Authors: Singh Shikha , Chauhan Parul , Ravi Makthala , Taneja Isha , Wahajuddin Wahajuddin , Yadav Prem. P.
Published: July 2015

An efficient methodology was developed for the synthesis of aromatic azo derivatives under mild reaction conditions utilizing CuBr with N-methylmorpholine N-oxide as an oxidant.
A high performance PVAm–HT membrane containing high-speed facilitated transport channels for CO2separation
Authors: Liao Jiayou , Wang Zhi , Gao Chengyun , Wang Ming , Yan Kai , Xie Xianmei , Zhao Song , Wang Jixiao , Wang Shichang
Published: July 2015

A PVAm–HT membrane containing high-speed facilitated transport channels combines the advantages of traditional facilitated transport membranes to a certain extent and obtains high permeance as well as high selectivity.
GSK3-mediated raptor phosphorylation supports amino-acid-dependent mTORC1-directed signalling
Authors: Stretton Clare , Hoffmann Thorsten M. , Munson Michael J. , Prescott Alan , Taylor Peter M. , Ganley Ian G. , Hundal Harinder S.
Published: July 2015

The mammalian or mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) is a ubiquitously expressed multimeric protein kinase complex that integrates nutrient and growth factor signals for the co-ordinated regulation of cellular metabolism and cell growth. Herein, we demonstrate that suppressing the cellular activity of glycogen synthase kinase-3 (GSK3), by use of pharmacological inhibitors or shRNA-mediated gene silencing, results in substantial reduction in amino acid (AA)-regulated mTORC1-directed signalling, as assessed by phosphorylation of multiple downstream mTORC1 targets. We show that GSK3 regulates mTORC1 activity through its ability to phosphorylate the mTOR-associated scaffold protein raptor (regulatory-associated protein of mTOR) on Ser859. We further demonstrate that either GSK3 inhibition or expression of a S859A mutated raptor leads to reduced interaction between mTOR and raptor and under these circumstances, irrespective of AA availability, there is a consequential loss in phosphorylation of mTOR substrates, such as p70S6K1 (ribosomal S6 kinase 1) and uncoordinated-51-like kinase (ULK1), which results in increased autophagic flux and reduced cellular proliferation.
44 pJ/bit energy‐efficiency K‐band OOK transmitter for wireless sensor networks
Authors: Chien Kuan‐Hsiu , Chiou Hwann‐Kaeo
Published: July 2015

A high energy‐efficiency K‐band on–off keying (OOK) transmitter in tsmc™ 90 nm CMOS technology is presented. The transmitter consists of a wideband voltage control oscillator (VCO), a frequency doubler and a switch‐type power amplifier with a chip area of 0.6 × 0.92 mm2. The VCO adopts a parasitic capacitance reduction technique to enhance the tuning range to 20.5%. The designed transmitter achieves an output power of 3 dBm with a 500 Mbit/s data rate from 19 to 23.1 GHz at 22.3 mW power consumption. The correspondent energy‐efficiency is 44 pJ/bit.
4‐channel 35 Gbit/s parallel CMOS LDD
Authors: Chen Yingmei , Gong Jianwei , Yao Jianguo , Tian Ling
Published: July 2015

The design of a 4‐channel 35 Gbit/s parallel laser diode driver (LDD) using 65 nm CMOS technology is presented. The LDD driver consists of an input buffer stage, a pre‐amplifier stage and an output driver stage. The three‐stage cascaded amplifiers constitute the pre‐amplifier stage, and an active feedback technique is employed to expand bandwidth without consuming a large area. The output driver stage introduces RC negative feedback and inductive shunt peaking techniques to broaden the bandwidth. Measurement results show that the operating rate of each channel is up to 35 Gbit/s and the power consumption per data rate is only 4.4 mW/(Gbit/s).
Digital excess loop delay compensation for high speed delta–sigma modulators
Authors: Jabbour C. , Nguyen V.T. , Srini V. , Aggarwal S.
Published: July 2015

A digital excess loop delay (ELD) compensation suited for high speed delta–sigma modulators is presented. Its operation is based on computing the digital outputs for all the possible values of the ELD compensation feedback and performing the selection in the digital domain. The proposed technique also uses a novel comparator sharing approach which minimises the number of comparators needed in the quantiser.
Resolution calculation and analysis in high‐resolution spaceborne SAR
Authors: Guo Ping , Zhang Linrang , Tang Shiyang
Published: July 2015

In high‐resolution spaceborne synthetic aperture radar (SAR), the hyperbolic range equation assumption fails to precisely describe the range history; thus, the traditional resolution analysis used for a spaceborne SAR design is imprecise. A curved orbit geometrical model based on the modified equivalent squint range model is graphically presented by vector notation. According to the model, the vectorial calculation of resolution is analytically presented, based on the gradient method. Additionally, a physical model is introduced to derive the effective integration time, which is quite difficult to derive due to the three‐dimensional curved orbit. Simulation results are presented to validate the proposed method.
Large raindrops against melting hail: calculation of specific differential attenuation, phase and reflectivity
Authors: Thurai M. , Chobanyan E. , Bringi V.N. , Notaroš B.M.
Published: July 2015

The specific differential attenuation caused by large raindrops and a special form of melting hail is computed and studied. Raindrops of smoothed conical shapes and hailstones modelled by an ice sphere surrounded by a water torus are considered. For the former, scattering computation is carried out by the T‐matrix method, while the higher‐order method of moments in the surface integral equation formulation is used for the latter. Results show a much higher specific differential attenuation factor for hail particles, with the smallest hail showing values similar to the largest raindrops. This can explain the higher than expected differential attenuation observed by C‐band radars in intense storms as reported in some previous studies. Results also show that the melting hail particles exhibit higher specific differential phase factor than large raindrops, but have similar differential reflectivity.
Miniaturised microstrip dual‐band bandpass filter using novel symmetric double‐spiral resonators for WLAN application
Authors: Wu Guo‐cheng , Wang Guangming , Liang Jiang Gang , Gao Xiang‐jun , Zhu Li
Published: July 2015

A miniaturised dual‐band bandpass filter (DB‐BPF) centred at 2.45/5.70 GHz using novel symmetric double‐spiral resonators is proposed. The measured and simulated results of the proposed DB‐BPF are in good agreement with each other except for a slight frequency shift downwards in the measurement. According to the measurements, the measured 3 dB bandwidths are 6.53% (2.35–2.51 GHz) at 2.45 GHz and 4.2% (5.61–5.85 GHz) at 5.70 GHz; the insertion losses including the loss from SMA connectors are <0.8/1.2 dB and the isolation between these two passbands is better than 20 dB from 2.54 to 5.59 GHz. The circuit area of the fabricated prototype is very compact, being only 7.7 × 9.4 mm.
Compressive sensing measurement matrix construction based on improved size compatible array LDPC code
Authors: Yuan Haiying , Song Hongying , Sun Xun , Guo Kun , Ju Zijian
Published: July 2015

ISC‐array LDPC code matrix is evolved from SC‐array LDPC code matrix to improve compressive sensing performance for large‐size sparse signal. When q is a prime number, no repetitive row occurs in the shift index of SC‐array LDPC code matrix, ISC‐array LDPC code matrix performs comparably with SC‐array LDPC code matrix. When q is a non‐prime number, some repetitive rows will appear in the shift index of SC‐array LDPC code matrix, which results in more 4‐cycles and decreases the compressive sensing performance. ISC‐array LDPC code matrix outperforms SC‐array LDPC code matrix by effectively reducing or even eliminating the repetitive rows according to their distribution rule, 4‐cycles are removed to the maximum extent. ISC‐array LDPC code matrix qualifies for compressive sensing because of satisfying RIP well. It also has good quasi‐cyclic structure and supports arbitrary code lengths. The simulations verify that the optimised ISC‐array LDPC code matrix is advantageous in the image reconstruction quality, the robustness to noise performance and the algorithm complexity.
Reassignment of ν2,3 IR band of the allyl radical in liquid helium nanodroplets
Authors: Habig Daniel , Leicht Daniel , Schwaab Gerhard , Havenith Martina
Published: July 2015

We have recorded the IR-spectrum of the deuterated allyl radical in the frequency range of the CH stretch vibrations in liquid helium nanodroplets. Comparison to the allyl radical spectrum enabled us to make an unambiguous assignment. Based on these new experimental measurements, a reassignment of the ν2,3 IR bands was deemed necessary.
Accelerating wavefunction in density-functional-theory embedding by truncating the active basis set
Authors: Bennie Simon J. , Stella Martina , Miller Thomas F. , Manby Frederick R.
Published: July 2015

Methods where an accurate wavefunction is embedded in a density-functional description of the surrounding environment have recently been simplified through the use of a projection operator to ensure orthogonality of orbital subspaces. Projector embedding already offers significant performance gains over conventional post-Hartree–Fock methods by reducing the number of correlated occupied orbitals. However, in our first applications of the method, we used the atomic-orbital basis for the full system, even for the correlated wavefunction calculation in a small, active subsystem. Here, we further develop our method for truncating the atomic-orbital basis to include only functions within or close to the active subsystem. The number of atomic orbitals in a calculation on a fixed active subsystem becomes asymptotically independent of the size of the environment, producing the required O(N0) scaling of cost of the calculation in the active subsystem, and accuracy is controlled by a single parameter. The applicability of this approach is demonstrated for the embedded many-body expansion of binding energies of water hexamers and calculation of reaction barriers of SN2 substitution of fluorine by chlorine in α-fluoroalkanes.
A new time dependent density functional algorithm for large systems and plasmons in metal clusters
Authors: Baseggio Oscar , Fronzoni Giovanna , Stener Mauro
Published: July 2015

A new algorithm to solve the Time Dependent Density Functional Theory (TDDFT) equations in the space of the density fitting auxiliary basis set has been developed and implemented. The method extracts the spectrum from the imaginary part of the polarizability at any given photon energy, avoiding the bottleneck of Davidson diagonalization. The original idea which made the present scheme very efficient consists in the simplification of the double sum over occupied-virtual pairs in the definition of the dielectric susceptibility, allowing an easy calculation of such matrix as a linear combination of constant matrices with photon energy dependent coefficients. The method has been applied to very different systems in nature and size (from H2 to [Au147]−). In all cases, the maximum deviations found for the excitation energies with respect to the Amsterdam density functional code are below 0.2 eV. The new algorithm has the merit not only to calculate the spectrum at whichever photon energy but also to allow a deep analysis of the results, in terms of transition contribution maps, Jacob plasmon scaling factor, and induced density analysis, which have been all implemented.
Fluidized bed coupled rotary reactor for nanoparticles coating via atomic layer deposition
Authors: Duan Chen-Long , Liu Xiao , Shan Bin , Chen Rong
Published: July 2015

A fluidized bed coupled rotary reactor has been designed for coating on nanoparticles (NPs) via atomic layer deposition. It consists of five major parts: reaction chamber, dosing and fluidizing section, pumping section, rotary manipulator components, as well as a double-layer cartridge for the storage of particles. In the deposition procedure, continuous fluidization of particles enlarges and homogenizes the void fraction in the particle bed, while rotation enhances the gas-solid interactions to stabilize fluidization. The particle cartridge presented here enables both the fluidization and rotation acting on the particle bed, demonstrated by the analysis of pressure drop. Moreover, enlarged interstitials and intense gas–solid contact under sufficient fluidizing velocity and proper rotation speed facilitate the precursor delivery throughout the particle bed and consequently provide a fast coating process. The cartridge can ensure precursors flowing through the particle bed exclusively to achieve high utilization without static exposure operation. By optimizing superficial gas velocities and rotation speeds, minimum pulse time for complete coating has been shortened in experiment, and in situ mass spectrometry showed the precursor usage can reach 90%. Inductively coupled plasma-optical emission spectroscopy results suggested a saturated growth of nanoscale Al2O3 films on spherical SiO2 NPs. Finally, the uniformity and composition of the shells were characterized by high angle annular dark field-transmission electron microscopy and energy dispersive X-ray spectroscopy.
Lattice model of linear telechelic polymer melts. II. Influence of chain stiffness on basic thermodynamic properties
Authors: Xu Wen-Sheng , Freed Karl F.
Published: July 2015

The lattice cluster theory (LCT) for semiflexible linear telechelic melts, developed in Paper I, is applied to examine the influence of chain stiffness on the average degree of self-assembly and the basic thermodynamic properties of linear telechelic polymer melts. Our calculations imply that chain stiffness promotes self-assembly of linear telechelic polymer melts that assemble on cooling when either polymer volume fraction ϕ or temperature T is high, but opposes self-assembly when both ϕ and T are sufficiently low. This allows us to identify a boundary line in the ϕ-T plane that separates two regions of qualitatively different influence of chain stiffness on self-assembly. The enthalpy and entropy of self-assembly are usually treated as adjustable parameters in classical Flory-Huggins type theories for the equilibrium self-assembly of polymers, but they are demonstrated here to strongly depend on chain stiffness. Moreover, illustrative calculations for the dependence of the entropy density of linear telechelic polymer melts on chain stiffness demonstrate the importance of including semiflexibility within the LCT when exploring the nature of glass formation in models of linear telechelic polymer melts.
Diffusion of nanoparticles in semidilute polymer solutions: A mode-coupling theory study
Authors: Dong Yunhong , Feng Xiaoqing , Zhao Nanrong , Hou Zhonghuai
Published: July 2015

We have proposed a theoretical formalism to study the long-time diffusion behavior of nanoparticles in polymer solutions by using mode-coupling theory (MCT). The non-hydrodynamic part Dmicro of the total diffusion coefficient D is calculated in the MCT framework where the polymer dynamic scattering function Γpp(k, t) in the solution plays an important role. By introducing an approximate summation form for Γpp(k, t), where both limits of short and long length scales are properly accounted for, we can compute Dmicro straightforwardly and investigate explicitly how D depends on the volume fraction ϕ of the polymer solution, the nanoparticle size R, the degree of polymerization N, as well as the entanglement effects. For illustration, we adopt our theoretical approach to analyze the diffusion of gold nanoparticles in semidilute poly(ethylene glycol) (PEG)-water solutions which has been studied in detail experimentally. We find that our theoretical results show very good quantitative agreements with the experimental data in many aspects, such as the strong dependence on ϕ, the large deviation from Stokes-Einstein relation particularly for small particles, as well as the effects of the PEG molecular weight. Such good agreements clearly demonstrate the validity of our MCT framework, which may serve as a good starting point to study many more complex dynamical behaviors associated with polymer solutions.
Chern-Simons action for inhomogeneous Virasoro group as extension of three dimensional flat gravity
Authors: Barnich Glenn , Giribet Gastón , Leston Mauricio
Published: July 2015

We initiate the study of a Chern-Simons action associated to the semi-direct sum of the Virasoro algebra with its coadjoint representation. This model extends the standard Chern-Simons formulation of three dimensional flat gravity and is similar to the higher-spin extension of three dimensional anti-de Sitter or flat gravity. The extension can also be constructed for the exotic but not for the cosmological constant deformation of flat gravity.
High repetition rate multi-channel source of high-power rf-modulated pulses
Authors: Ulmaskulov M. R. , Pedos M. S. , Rukin S. N. , Sharypov K. A. , Shpak V. G. , Shunailov S. A. , Yalandin M. I. , Romanchenko I. V. , Rostov V. V.
Published: July 2015

This paper presents the results of testing a high voltage pulse generator based on parallel gyromagnetic nonlinear transmission lines filled with saturable ferrite. The generator is capable of producing almost identical stable rf-modulated nanosecond high voltage pulses in each of the two, or four, parallel output channels. The output voltage amplitude in each channel can reach −285 or −180 kV, respectively, with a rf modulation depth of up to 60%. Drive pulses were produced as the packets of duration 1–5 s at a pulse repetition frequency of 800 Hz using a driver equipped with all-solid-state switches. Splitting the driver pulse provided electric field strengths in the channels which were below the breakdown field strength of the transmission lines. As a result, the use of nonlinear transmission lines of reduced diameter made it possible to increase the center frequency of the excited rf oscillations to ∼2 GHz.
Polymer-ionic liquid ternary systems for Li-battery electrolytes: Molecular dynamics studies of LiTFSI in a EMIm-TFSI and PEO blend
Authors: Costa Luciano T. , Sun Bing , Jeschull Fabian , Brandell Daniel
Published: July 2015

This paper presents atomistic molecular dynamics simulation studies of lithium bis(trifluoromethane)sulfonylimide (LiTFSI) in a blend of 1-ethyl-3-methylimidazolium (EMIm)-TFSI and poly(ethylene oxide) (PEO), which is a promising electrolyte material for Li- and Li-ion batteries. Simulations of 100 ns were performed for temperatures between 303 K and 423 K, for a Li:ether oxygen ratio of 1:16, and for PEO chains with 26 EO repeating units. Li+ coordination and transportation were studied in the ternary electrolyte system, i.e., PEO16LiTFSI⋅1.0 EMImTFSI, by applying three different force field models and are here compared to relevant simulation and experimental data. The force fields generated significantly different results, where a scaled charge model displayed the most reasonable comparisons with previous work and overall consistency. It is generally seen that the Li cations are primarily coordinated to polymer chains and less coupled to TFSI anion. The addition of EMImTFSI in the electrolyte system enhances Li diffusion, associated to the enhanced TFSI dynamics observed when increasing the overall TFSI anion concentration in the polymer matrix.
Nonlinear damping of a finite amplitude whistler wave due to modified two stream instability
Authors: Saito Shinji , Nariyuki Yasuhiro , Umeda Takayuki
Published: July 2015

A two-dimensional, fully kinetic, particle-in-cell simulation is used to investigate the nonlinear development of a parallel propagating finite amplitude whistler wave (parent wave) with a wavelength longer than an ion inertial length. The cross field current of the parent wave generates short-scale whistler waves propagating highly oblique directions to the ambient magnetic field through the modified two-stream instability (MTSI) which scatters electrons and ions parallel and perpendicular to the magnetic field, respectively. The parent wave is largely damped during a time comparable to the wave period. The MTSI-driven damping process is proposed as a cause of nonlinear dissipation of kinetic turbulence in the solar wind.
Kinetics of aggregation of an anisotropic model of self-assembling molecules
Authors: Khan Siddique , Haaga Jason , Gunton J. D.
Published: July 2015

We study the kinetics of aggregation of a two site model of interacting spherical molecules. A given site on one molecule can interact with one or more sites on other neighboring molecules. The sites represent the result of a simple coarse graining of putative amino acid residues or two specifically designed sites on a colloidal particle. We study the kinetics and equilibrium morphology for a fixed angle between the two sites, for several angles between 30° and 150°. In the model, the sites interact via an attractive Asakura-Oosawa potential and the molecules have the usual hard sphere repulsion interaction. We find a transition from a micelle-like morphology at small angles to a rod-like morphology at intermediate angles and to a gel-like structure at values of the angle greater than about ninety degrees. However, at 150 degrees, after a long induction time during which there is no aggregation, we observe a nucleation and growth process that leads to a final spherical-like aggregate. Our results show that this angle is a control parameter for the kinetics and equilibrium properties of the system.
Enhancing of magnetic flux pinning in YBa2Cu3O7−x/CuO granular composites
Authors: Ushakov A. V. , Karpov I. V. , Lepeshev A. A. , Petrov M. I.
Published: July 2015

This paper shows that the combination of self-assembled structures in the form of “whiskers” and nanoparticles, which appear as a result of the joint sintering powders YBa2Cu3O7−x and arc nanopowders CuO, leads to a significant increase in the current density and the appearance of the peak effect in strong magnetic fields range. Very high critical current density appears from a complex vortex pinning, where the defects in the form of “whiskers” provides more energy of pinning, and nanoparticles inhibit the flux creep. Regulation of the morphology of such structures can be achieved by simple change of the concentration of nanodispersed additives. It is shown that the optimal additive is CuO equal to 20 wt. %.
Analysis based on global model of nitrogen plasma produced by pulsed microwave at low pressure
Authors: Qiu Feng , Yan Eryan , Meng Fanbao , Liu Minghai , Ma Hongge
Published: July 2015

This paper analyzes certain evolution processes in nitrogen plasmas discharged using pulsed microwaves at low pressure. Comparing the results obtained from the global model incorporating diffusion and the microwave transmission method, the temporal variation of the electron density is analyzed. With a discharge pressure of 300 Pa, the results obtained from experiments and the global model calculation show that when the discharge begins the electron density in the plasma rises quickly, to a level above the critical density corresponding to the discharge microwave frequency, but falls slowly when the discharge microwave pulse is turned off. The results from the global model also show that the electron temperature increases rapidly to a peak, then decays after the electron density reaches the critical density, and finally decreases quickly to room temperature when the discharge microwave pulse is turned off. In the global model, the electron density increases because the high electron temperature induces a high ionization rate. The decay of the electron density mainly comes from diffusion effect.
Hydrodynamic instability growth of three-dimensional, “native-roughness” modulations in x-ray driven, spherical implosions at the National Ignition Facility
Authors: Smalyuk V. A. , Weber S. V. , Casey D. T. , Clark D. S. , Field J. E. , Haan S. W. , Hammel B. A. , Hamza A. V. , Hoover D. E. , Landen O. L. , Nikroo A. , Robey H. F. , Weber C. R.
Published: July 2015

Hydrodynamic instability growth experiments with three-dimensional (3-D) surface-roughness modulations were performed on plastic (CH) shell spherical implosions at the National Ignition Facility (NIF) [E. M. Campbell, R. Cauble, and B. A. Remington, AIP Conf. Proc. 429, 3 (1998)]. The initial capsule outer-surface roughness was similar to the standard specifications (“native roughness”) used in a majority of implosions on NIF. The experiments included instability growth measurements of the perturbations seeded by the thin membranes (or tents) used to hold the capsules inside the hohlraums. In addition, initial modulations included two divots used as spatial fiducials to determine the convergence in the experiments and to check the accuracy of 3D simulations in calculating growth of known initial perturbations. The instability growth measurements were performed using x-ray, through-foil radiography of one side of the imploding shell, based on time-resolved pinhole imaging. Averaging over 30 similar images significantly increases the signal-to-noise ratio, making possible a comparison with 3-D simulations. At a convergence ratio of ∼3, the measured tent and divot modulations were close to those predicted by 3-D simulations (within ∼15%–20%), while measured 3-D, broadband modulations were ∼3–4 times larger than those simulated based on the growth of the known imposed initial surface modulations. In addition, some of the measured 3-D features in x-ray radiographs did not resemble those characterized on the outer capsule surface before the experiments. One of the hypotheses to explain the results is based on the increased instability amplitudes due to modulations of the oxygen content in the bulk of the capsule. As the target assembly and handling procedures involve exposure to UV light, this can increase the uptake of the oxygen into the capsule, with irregularities in the oxygen seeding hydrodynamic instabilities. These new experimental results have prompted looking for ways to reduce UV light exposure during target fabrication.
The global build-up to intrinsic edge localized mode bursts seen in divertor full flux loops in JET
Authors: Chapman S. C. , Dendy R. O. , Todd T. N. , Watkins N. W. , Calderon F. A. , Morris J. ,   JET Contributors
Published: July 2015

A global signature of the build-up to an intrinsic edge localized mode (ELM) is found in the temporal analytic phase of signals measured in full flux azimuthal loops in the divertor region of JET. Toroidally integrating, full flux loop signals provide a global measurement proportional to the voltage induced by changes in poloidal magnetic flux; they are electromagnetically induced by the dynamics of spatially integrated current density. We perform direct time-domain analysis of the high time-resolution full flux loop signals VLD2 and VLD3. We analyze plasmas where a steady H-mode is sustained over several seconds during which all the observed ELMs are intrinsic; there is no deliberate intent to pace the ELMing process by external means. ELM occurrence times are determined from the Be II emission at the divertor. We previously [Chapman et al., Phys. Plasmas 21, 062302 (2014); Chapman et al., in 41st EPS Conference on Plasma Physics, Europhysics Conference Abstracts (European Physical Society, 2014), Vol. 38F, ISBN 2-914771-90-8] found that the occurrence times of intrinsic ELMs correlate with specific temporal analytic phases of the VLD2 and VLD3 signals. Here, we investigate how the VLD2 and VLD3 temporal analytic phases vary with time in advance of the ELM occurrence time. We identify a build-up to the ELM in which the VLD2 and VLD3 signals progressively align to the temporal analytic phase at which ELMs preferentially occur, on a ∼2−5ms timescale. At the same time, the VLD2 and VLD3 signals become temporally phase synchronized with each other, consistent with the emergence of coherent global dynamics in the integrated current density. In a plasma that remains close to a global magnetic equilibrium, this can reflect bulk displacement or motion of the plasma. This build-up signature to an intrinsic ELM can be extracted from a time interval of data that does not extend beyond the ELM occurrence time, so that these full flux loop signals could assist in ELM prediction or mitigation.
Induction and control of room-temperature ferromagnetism in dilute Fe-doped SrTiO3 ceramics
Authors: He Ju , Lu Xiaomei , Zhu Weili , Hou Yanyan , Ti Ruixia , Huang Fengzhen , Lu Xueliang , Xu TingTing , Su Jie , Zhu Jinsong
Published: July 2015

The magnetic characteristics of dilute Fe-doped SrTiO3 ceramics are studied. The room-temperature ferromagnetism (with transition temperature around 650 K) is successfully realized in Sr0.98Ti0.9Fe0.1O3−δ and Sr0.98Ti0.92Fe0.1O3−δ ceramics. It is found that a fine-tuning of the components could alter the substitution sites of Fe ions and in-turn modulates the magnetism of the material. A systematic analysis reveals that the co-substitution of Fe ions at nonequivalent A and B sites in ABO3 type perovskites is in favor of the ferromagnetism, which could be attributed to the mixed-valence-states of Fe ions and the variation of exchange interactions. This work provides an innovation for the induction and control of ferromagnetism in dilute magnetic materials.
Application of improved artificial neural networks in short-term power load forecasting
Authors: Wei Sun , Mohan Liu
Published: July 2015

Power load forecasting is a key element for power system management and planning. However, it has been proven to be a hard task due to various unstable factors. This paper presents a forecasting methodology based on this particular type of neural network. The scope of this study presents a solution for short-term load forecasting based on a three-stage model which starts with pattern recognition via self-organizing map (SOM), a clustering of the previous partition by K-means algorithm, and finally demand forecasting for each cluster with back propagation neural network (BPNN) improved by additional momentum and variable learning rate methods. The effectiveness of SOM-K-BPNN model has been verified by the final simulation which shows that the proposed model outperforms the BPNN model with default parameters and Grey System GM (1, 1); therefore, empirical results show that the proposed SOM-K-BPNN model is feasible and can fulfil the short-term load forecasting requirements of China.
Micro-structural characterization of low resistive metallic Ni germanide growth on annealing of Ni-Ge multilayer
Authors: Swain Mitali , Singh Surendra , Bhattacharya Debarati , Singh Ajay , Tokas R.B. , Prajapat C. L. , Basu Saibal
Published: July 2015

Nickel-Germanides are an important class of metal semiconductor alloys because of their suitability in microelectronics applications. Here we report successful formation and detailed characterization of NiGe metallic alloy phase at the interfaces of a Ni-Ge multilayer on controlled annealing at relatively low temperature ∼ 250 °C. Using x-ray and polarized neutron reflectometry, we could estimate the width of the interfacial alloys formed with nanometer resolution and found the alloy stoichiometry to be equiatomic NiGe, a desirable low-resistance interconnect. We found significant drop in resistance (∼ 50%) on annealing the Ni-Ge multilayer suggesting metallic nature of alloy phase at the interfaces. Further we estimated the resistivity of the alloy phase to be ∼ 59μΩ cm.