bluuebunny/crossref_metadata_2025 huggingface dataset:
A hydroxyl functionalized ionic liquid-based ultrasound-assisted surfactant-enhanced emulsification microextraction for the determination of herbicides in water samples
Authors: Huang Zhihong , Meng Xiaolu , Liu Ming , Wang Suli
Published: September 2014

This paper describes a hydroxyl functionalized ionic liquid (FIL), 1-hydroxyl hexyl-3-methylimidazoliumbis[(trifluoromethyl)sulfonyl] imide [HHyMIMTf2N] used for the extraction and preconcentration of 7 herbicides from water samples by ultrasound-assisted surfactant-enhanced emulsification microextraction.
A novel electrochemical sugar recognition system using a ruthenium complex and phenylboronic acid assembled on gold nanoparticles
Authors: Endo Akira , Kimura Masamitsu , Hashimoto Takeshi , Hayashita Takashi
Published: September 2014

A novel electrochemical sugar recognition system using a tris(acetylacetonato)ruthenium complex and phenylboronic acid assembled on gold nanoparticles.
The influence of nitrogen dioxide on the determination of hydrogen cyanide in mainstream and sidestream cigarette smoke and the improvement of the determination method by continuous flow analyzer
Authors: Liu Xingyu , Ma Li , Zhou Jun , Ma Yanjun , Bai Ruoshi , Yan Lihong
Published: September 2014

Hydrogen cyanide is a well-known toxic component in cigarette smoke. Accurate determination of hydrogen cyanide is of great significance to assess the risk of cigarettes to public health.
Cancer-targeted near infrared imaging using rare earth ion-doped ceramic nanoparticles
Authors: Zako Tamotsu , Yoshimoto Miya , Hyodo Hiroshi , Kishimoto Hidehiro , Ito Masaaki , Kaneko Kazuhiro , Soga Kohei , Maeda Mizuo
Published: September 2014

Cancer-specific NIR–NIR imaging was demonstrated using streptavidin-functionalized rare earth ion-doped yttrium oxide nanoparticles and biotinylated antibodies on cancer cells and human colon cancer tissues.
Luminescent terbium-containing metal–organic framework films: new approaches for the electrochemical synthesis and application as detectors for explosives
Authors: Campagnol Nicolò , Souza Ernesto Rezende , De Vos Dirk E. , Binnemans Koen , Fransaer Jan
Published: September 2014

The flexibility of the electrochemical synthesis of MOFs is illustrated by the preparation of well-adhering layers of luminescent MOFs on electrically conductive solid substrates.
Introducing deep eutectic solvents as biorenewable media for Au(i)-catalysed cycloisomerisation of γ-alkynoic acids: an unprecedented catalytic system
Authors: Rodríguez-Álvarez María J. , Vidal Cristian , Díez Josefina , García-Álvarez Joaquín
Published: September 2014

Cycloisomerisation reactions of γ-alkynoic acids can be conveniently performed in the eutectic mixture 1ChCl/2Urea at room temperature, under air and in the absence of co-catalysts by using a novel iminophosphorane–Au(i) complex.
Local visualization of catalytic activity at gas evolving electrodes using frequency-dependent scanning electrochemical microscopy
Authors: Chen Xingxing , Maljusch Artjom , Rincón Rosalba A. , Battistel Alberto , Bandarenka Aliaksandr S. , Schuhmann Wolfgang
Published: September 2014

A new concept for the localized characterization of gas evolving electrodes based on scanning electrochemical microscopy (SECM) is suggested.
Chemical Reaction-Induced Multi-molecular Polarization (CRIMP)
Authors: Lee Y. , Zacharias N. M. , Piwnica-Worms D. , Bhattacharya P. K.
Published: September 2014

Here we present a novel hyperpolarization method, Chemical Reaction-Induced Multi-molecular Polarization (CRIMP), which could be applied to the study of severalin vivoprocesses simultaneously including glycolysis, TCA cycle, fatty acid synthesis and pH mapping.
Modelling potential/current distribution in microbial electrochemical systems shows how the optimal bioanode architecture depends on electrolyte conductivity
Authors: Lacroix Rémy , Silva Serge Da , Gaig Monica Viaplana , Rousseau Raphael , Délia Marie-Line , Bergel Alain
Published: September 2014

Modeling distribution of electrostatic potential in the a microbial electrolysis cell shows the great dependence of the optimal design on the ionic conductivity of the medium.
Low-energy vibrational spectra of flexible diphenyl molecules: biphenyl, diphenylmethane, bibenzyl and 2-, 3- and 4-phenyltoluene
Authors: Martin-Drumel M. A. , Pirali O. , Falvo C. , Parneix P. , Gamboa A. , Calvo F. , Bréchignac Ph.
Published: September 2014

Gas phase spectra of six bi-phenyl molecules are reported allowing an accurate determination of their active low-frequency vibrational modes.
Influence of single- and double-flame spray pyrolysis on the structure of MnOx/γ-Al2O3and FeOx/γ-Al2O3catalysts and their behaviour in CO removal under lean exhaust gas conditions
Authors: Tepluchin Marina , Pham David K. , Casapu Maria , Mädler Lutz , Kureti Sven , Grunwaldt Jan-Dierk
Published: September 2014

Manganese and iron oxides on alumina prepared by two-nozzle flame synthesis show improved CO-oxidation activity due to minimized composite formation.
An improved interolog mapping-based computational prediction of protein–protein interactions with increased network coverage
Authors: Folador Edson Luiz , Hassan Syed Shah , Lemke Ney , Barh Debmalya , Silva Artur , Ferreira Rafaela Salgado , Azevedo Vasco
Published: September 2014

Automated and efficient methods that map ortholog interactions from several organisms and public databases (pDB) are needed to identify new interactions in an organism of interest (interolog mapping).
The nociceptin receptor (NOPR) and its interaction with clinically important agonist molecules: a membrane molecular dynamics simulation study
Authors: Kothandan Gugan , Gadhe Changdev G. , Balupuri Anand , Ganapathy Jagadeesan , Cho Seung Joo
Published: September 2014

The nociceptin receptor (NOPR) is an orphan G protein-coupled receptor that contains seven transmembrane helices.
Isoxazole derivatives of 6-fluoro-N-(6-methoxybenzo[d]thiazol-2-yl)benzo[d]thiazol-2-amine and N-(pyrimidin-2-yl)benzo[d]thiazol-2-amine: regulation of cell cycle and apoptosis by p53 activation via mitochondrial-dependent pathways
Authors: Kumbhare Ravindra M. , Dadmal Tulshiram L. , Devi T. Anjana , Kumar Dinesh , Kosurkar Umesh B. , Chowdhury Debabrata , Appalanaidu K. , Rao Y. Khageswara , Ramaiah M. Janaki , Bhadra Manika Pal
Published: September 2014

The compounds depicted were shown to induce DNA damage and activate p53, which in turn activates Bax and decreases Bcl2 levels. This resulted in apoptosis in Colo205 cells.
Thiourea as an efficient organocatalyst for the transfer hydrogenation of 2-substituted quinoline derivatives
Authors: Qiao Xiang , Zhang Zhiguo , Bao Zongbi , Su Baogen , Xing Huabin , Yang Qiwei , Ren Qilong
Published: September 2014

This study reports on the first transfer hydrogenation of 2-substituted quinolines promoted by a thiourea catalyst with Hantzsch 1,4-dihydropyridine as the hydrogen source.
Fabrication of a superhydrophobic graphene surface with excellent mechanical abrasion and corrosion resistance on an aluminum alloy substrate
Authors: Liu Yan , Zhang Jijia , Li Shuyi , Wang Yaming , Han Zhiwu , Ren Luquan
Published: September 2014

A superhydrophobic graphene film with excellent mechanical abrasion resistance and corrosion resistance was successfully deposited on Al alloy using a spin-coating method.
Polarizability as a landmark property for fullerene chemistry and materials science
Authors: Sabirov Denis Sh.
Published: September 2014

The review summarizes data on dipole polarizability of fullerenes and their derivatives, covering the most widespread classes of fullerene-containing molecules (fullerenes, fullerene exohedral derivatives, fullerene dimers, endofullerenes, fullerene ions, and derivatives with ionic bonds).
Nitrogen containing graphene-like structures from pyrolysis of pyrimidine polymers for polymer/graphene hybrid field effect transistors
Authors: Gunathilake Samodha S. , Huang Peishen , Bhatt Mahesh P. , Rainbolt Elizabeth A. , Stefan Mihaela C. , Biewer Michael C.
Published: September 2014

Synthesis of pyrimidine polymers, their pyrolysis to obtain nitrogen containing graphene like structures and application of these graphitic materials in polymer/graphene hybrid field effect transistors is reported.
Design and fabrication of surface-enhanced Raman scattering substrate from DNA–gold nanoparticles assembly with 2–3 nm interparticle gap
Authors: Zhang Li , Ma Hongwei , Yang Liangbao
Published: September 2014

This study provides a one-step strategy for preparing DNA–Au hybrids as SERS-active substrates by the simple mixing of DNA and Au colloids.
Effects of Cu addition on band gap energy, density of state effective mass and charge transport properties in Bi2Te3 composites
Authors: Yu Hyeon Jin , Jeong Mahn , Lim Young Soo , Seo Won-Seon , Kwon O-Jong , Park Cheol-Hee , Hwang Hae-Jin
Published: September 2014

The effects of Cu addition on band gap energy, effective mass, and charge transport properties in n-type CuxBi2Te3 composites are presented.
Blue phase-mixed anatase–rutile TiO2 heterogeneous junction composites: surface defect-induced reconstruction by F ion and superior lithium-storage properties
Authors: Wang Hai , Yang Hongxing , Lu Lin
Published: September 2014

The surface defect reconstruction of blue phase-mixed anatase–rutile TiO2 heterogeneous junction composites plays a crucial role in the enhancement of lithium-ion batteries.
Co-delivery of doxorubicin and curcumin by polymeric micelles for improving antitumor efficacy on breast carcinoma
Authors: Sun Lu , Deng Xiaohui , Yang Xi , Li Zhaojun , Wang Zhihan , Li Ling , Wu Qinjie , Peng Feng , Liu Lei , Gong Changyang
Published: September 2014

Polymeric micelles co-delivered hydrophilic doxorubicin and hydrophobic curcumin improved cytotoxicity, apoptosis, and cellular uptakein vitroand enhanced antitumor and anti-metastasis activityin vivoon breast carcinoma.
One-step preparation of ultrathin nitrogen-doped carbon nanosheets with ultrahigh pore volume for high-performance supercapacitors
Authors: Peng Hui , Ma Guofu , Sun Kanjun , Mu Jingjing , Lei Ziqiang
Published: September 2014

A facile one-step activation and nitrogen-doping combination method is developed for preparation of nitrogen-doped graphene-like carbon nanosheets (N-CNSs).
A study on effects of naphthalimide derivative-capped quantum dots on the cellular internalization, proliferation, and apoptosis ability
Authors: Zhao Mei-Xia , Zeng Er-Zao , Li Yang , Wang Chao-Jie
Published: September 2014

Naphthalimide derivative-capped QDs effectively inhibited the proliferation of cells due to apoptosis via a ROS mediated mitochondrial dysfunction.
Bacteria repelling poly(methylmethacrylate-co-dimethylacrylamide) coatings for biomedical devices
Authors: Venkateswaran Seshasailam , Wu Mei , Gwynne Peter J. , Hardman Ailsa , Lilienkampf Annamaria , Pernagallo Salvatore , Blakely Garry , Swann David G. , Gallagher Maurice P. , Bradley Mark
Published: September 2014

A polymer microarray screen identified poly(methylmethacrylate-co-dimethylacrylamide) as a bacteria repelling surface, which substantially reduced binding of bacteria on coated catheters.
Naturally self-assembled nickel nanolattice
Authors: Singh Jaiveer , Kaurav Netram , Lalla Niranjan Prasad , Okram Gunadhor Singh
Published: September 2014

Hexagonal close-packed nanolattices of monodispersed nickel nanoparticles have been discovered with trioctylphosphine as one of the surfactants, without extra forces. Their origin appears to be due to electrostatic interactions. This finding is expected to open up a new era in natural nanolattice research.
Polymerisable octahedral rhenium cluster complexes as precursors for photo/electroluminescent polymers
Authors: Efremova Olga A. , Brylev Konstantin A. , Kozlova Olena , White Matthew S. , Shestopalov Michael A. , Kitamura Noboru , Mironov Yuri V. , Bauer Siegfried , Sutherland Andrew J.
Published: September 2014

Re-containing cluster complexes have been developed and polymerised to generate photo/electroluminescent materials, which can be used to construct PLEDs.
Offsetting the problem of charge trapping in white polymer light-emitting diodes using a fluorenone-based luminogen
Authors: Ananthakrishnan Soundaram Jeevarathinam , Varathan Elumalai , Somanathan Narayanasastri , Subramanian Venkatesan , Mandal Asit Baran , Sudha Janardanan D. , Ramakrishnan Rajaraman
Published: September 2014

AA Fluorenone-based AIEE luminogen is used a covalent dopant to design a white light emitting copolymer with minimized charge trapping.
Characterization of VPS34-IN1, a selective inhibitor of Vps34, reveals that the phosphatidylinositol 3-phosphate-binding SGK3 protein kinase is a downstream target of class III phosphoinositide 3-kinase
Authors: Bago Ruzica , Malik Nazma , Munson Michael J. , Prescott Alan R. , Davies Paul , Sommer Eeva , Shpiro Natalia , Ward Richard , Cross Darren , Ganley Ian G. , Alessi Dario R.
Published: September 2014

The Vps34 (vacuolar protein sorting 34) class III PI3K (phosphoinositide 3-kinase) phosphorylates PtdIns (phosphatidylinositol) at endosomal membranes to generate PtdIns(3)P that regulates membrane trafficking processes via its ability to recruit a subset of proteins possessing PtdIns(3)P-binding PX (phox homology) and FYVE domains. In the present study, we describe a highly selective and potent inhibitor of Vps34, termed VPS34-IN1, that inhibits Vps34 with 25 nM IC50in vitro, but does not significantly inhibit the activity of 340 protein kinases or 25 lipid kinases tested that include all isoforms of class I as well as class II PI3Ks. Administration of VPS34-IN1 to cells induces a rapid dose-dependent dispersal of a specific PtdIns(3)P-binding probe from endosome membranes, within 1 min, without affecting the ability of class I PI3K to regulate Akt. Moreover, we explored whether SGK3 (serum- and glucocorticoid-regulated kinase-3), the only protein kinase known to interact specifically with PtdIns(3)P via its N-terminal PX domain, might be controlled by Vps34. Mutations disrupting PtdIns(3)P binding ablated SGK3 kinase activity by suppressing phosphorylation of the T-loop [PDK1 (phosphoinositide-dependent kinase 1) site] and hydrophobic motif (mammalian target of rapamycin site) residues. VPS34-IN1 induced a rapid ~50–60% loss of SGK3 phosphorylation within 1 min. VPS34-IN1 did not inhibit activity of the SGK2 isoform that does not possess a PtdIns(3)P-binding PX domain. Furthermore, class I PI3K inhibitors (GDC-0941 and BKM120) that do not inhibit Vps34 suppressed SGK3 activity by ~40%. Combining VPS34-IN1 and GDC-0941 reduced SGK3 activity ~80–90%. These data suggest SGK3 phosphorylation and hence activity is controlled by two pools of PtdIns(3)P. The first is produced through phosphorylation of PtdIns by Vps34 at the endosome. The second is due to the conversion of class I PI3K product, PtdIns(3,4,5)P3 into PtdIns(3)P, via the sequential actions of the PtdIns 5-phosphatases [SHIP1/2 (Src homology 2-domain-containing inositol phosphatase 1/2)] and PtdIns 4-phosphatase [INPP4B (inositol polyphosphate 4-phosphatase type II)]. VPS34-IN1 will be a useful probe to delineate physiological roles of the Vps34. Monitoring SGK3 phosphorylation and activity could be employed as a biomarker of Vps34 activity, in an analogous manner by which Akt is used to probe cellular class I PI3K activity. Combining class I (GDC-0941) and class III (VPS34-IN1) PI3K inhibitors could be used as a strategy to better analyse the roles and regulation of the elusive class II PI3K.
Coning target micro‐motion feature extraction via scattering centre reconstruction
Authors: He Feiyang , Wang Peng , Xu Xiaojian
Published: September 2014

The issue of extracting micro‐Doppler (mD) information of the coning target radar echoes with or without Doppler aliasing is considered using scattering centre reconstruction combined with the time–frequency analysis (TFA) method. The effectiveness of the presented method is investigated using real measured radar signal experiments. For radar echoes without Doppler aliasing, extraction of the mD information of the coning target using traditional TFA can be obtained. However, using the presented method the mD information is more precise. For radar echoes with Doppler aliasing, there are significant differences in precision between the traditional TFA and the presented methods, and the mD information is smeared using the traditional TFA. Nevertheless, the extraction of mD information can be achieved by the presented method.
Laser dynamics under frequency‐shifted optical feedback with random phase
Authors: Nikolić M. , Taimre T. , Tucker J.R. , Lim Yah Leng , Bertling K. , Rakić A.D.
Published: September 2014

The rate‐equation model for a semiconductor laser under optical feedback is a useful tool for studying complex laser dynamics. Optical feedback from scatterers suspended in fluid flow and rough bodies in motion consists of many, spectrally close, Doppler‐shifted frequency components with random phase. How this type of feedback is included in the well‐established Lang and Kobayashi model is clarified, resulting in simulated results that agree well with the experiment in both time and frequency domains. Equipped with this model, the dynamic effects of laser feedback systems measuring flow or rough targets in motion may be studied numerically.
White space cognitive radio prototype and its test results for white space trial
Authors: Song Chunyi , Harada Hiroshi
Published: September 2014

This study introduces a white space device (WSD) prototype developed for the white space technology trial organised by Infocomm Development Authority of Singapore (Singapore Trial). A draft regulation was issued by the Infocomm Development Authority for the Singapore Trial. To meet the strict requirements on some performance criteria defined in the draft regulation, some solutions on designs of the system and algorithm are developed and adopted to the WSD prototype. The prototype has a complete design of hardware and software to realise real‐time and intelligent operations of periodical spectrum sensing and database access, dynamic frequency selection and non‐continuous transmission featured with low adjacent channel power leakage and power control. During the Singapore Trial, tests were conducted to check the above cognitive radio (CR) technologies and CR‐enabled operations. The official test results verify the effectiveness of implemented system and algorithm designs.
Kernel‐based sliding mode control for visual servoing system
Authors: Parsapour Mahsa , Taghirad Hamid D.
Published: September 2014

In this study, a new approach to design a controller for a visual servoing (VS) system is proposed. Kernel‐measurement is used to track the motion of a featureless object which is defined as sum of weighted‐image value through smooth kernel functions. This approach was used in kernel‐based VS (KBVS). To improve the tracking error and expand the stability region, sliding mode control is integrated with kernel measurement. Proportional–integral‐type sliding surface is chosen as a suitable manifold to produce the required control effort. Moreover, the stability of this algorithm is analysed via Lyapunov theory and its performance is verified experimentally by implementing the proposed method on a five degrees of freedom industrial robot. Through experimental results, it is shown that the performance of tracking error in the proposed method is more suitable than KBVS, for a wider workspace and when the object is placed near the boundary of the camera's field of view.
Carbon dioxide capture and storage planning considering emission trading system for a generation corporation under the emission reduction policy in China
Authors: Lu Zhigang , Lu Congying , Feng Tao , Zhao Hao
Published: September 2014

Power generation corporations face challenges from emission reduction targets (ERTs) of government policy from the increasingly explicit demand for carbon dioxide (CO2) emission reduction. CO2 capture and storage (CCS) is receiving considerable attention as a potential greenhouse gas mitigation option for fossil‐fuelled power plants. In this study, a mathematical model is built to select the proper plants to deploy CCS under the Emission Trading System. The model considers factors such as clean energy development, fuel price fluctuation and economic level growth in the next five years to maximise the profit of the whole corporation under the premise of fulfilling the ERT in China. The Black‐Scholes option pricing theory is used to analyse the investment potential amid yearly carbon price fluctuations. A discrete bacterial colony chemotaxis algorithm is then used to solve the model. The model is illustrated by an example of 11 plants with 17 units subordinated to a certain corporation in Hebei, China. The results show that the CCS planning situations in three carbon‐trading scenarios and their option values can effectively provide the investment strategy references for power generation corporations.
Reduced‐dimension clutter suppression method for airborne multiple‐input multiple‐output radar based on three iterations
Authors: Jie He , Da‐zheng Feng , Lun Ma
Published: September 2014

A reduced‐dimension space time adaptive processing (STAP) for airborne multiple‐input multiple‐output (MIMO) radar based on three iterations is proposed. The optimum filter for MIMO‐STAP is described as a separable filter, and the optimal weight vector in high dimension can be iteratively solved by three lower dimension weight vectors. Consequently, the quite high sample support and computational complexity in optimal MIMO‐STAP can be efficiently reduced. For short data records, the proposed method can achieve better clutter suppression performance. Simulation results demonstrate the effectiveness of the proposed method.
Robust control strategy for electrically driven robot manipulators: adaptive fuzzy sliding mode
Authors: Soltanpour Mohammad Reza , Otadolajam Pooria , Khooban Mohammad Hassan
Published: September 2014

In this study, a sliding mode controller is designed to control the position tracking of robot manipulator. The proposed control has global asymptotical stability in the presence of structured uncertainties, un‐structured uncertainties and un‐modelled dynamics of the robot manipulator as well as in motors dynamics. The proposed control structure is designed in such a way that initially, by using inverse dynamic method, it reduces the uncertainties bound and finally, sliding mode control eliminates the influence of the remaining uncertainties in closed‐loop system stability. Further, in control input for eliminating undesirable chattering phenomena using the fuzzy logic, an adaptive fuzzy approximator is designed in such way that approximates the uncertainty bounds. Mathematical proof shows that the adaptive fuzzy sliding mode control of a closed‐loop system has global asymptotical stability. Since the number of existing fuzzy rules are low in adaptive fuzzy approximator rules base and in single input–single output form, so control input computational load is very low and this order makes the proposed control of practical implementation possible. To evaluate the performance of the proposed controller, a case study on a robot manipulator with two degrees of freedom is implemented. Simulation results show the desired performance of the proposed controller.
Theoretical studies of 63Cu2+ orbital Knight shifts of HgBa2Ca2Cu3O8+δ
Authors: Kuang Min-Quan , Wu Shao-Yi , Hu Xian-Fen
Published: September 2014

The orbital Knight shifts and g factors for the tetragonal 63Cu2+ site in HgBa2Ca2Cu3O8+δ at 133 and 115 K are theoretically investigated based on the high-order perturbation formulae of these quantities for a 3d9 ion situated into tetragonally elongated octahedra. The theoretical results reveal good agreement with the observed values. The significant anisotropies of the Knight shifts are illustrated as the considerable local tetragonal elongation distortions of the five-coordinated Cu2+ sites. The results at different temperatures are also discussed in view of the local structure of the Cu2+ sites.
Low-temperature positron annihilation study of B+-ion implanted PMMA
Authors: Kavetskyy T. S. , Tsmots V. M. , Voloshanska S. Ya. , Šauša O. , Nuzhdin V. I. , Valeev V. F. , Osin Y. N. , Stepanov A. L.
Published: September 2014

Temperature dependent positron annihilation lifetime spectroscopy (PALS) measurements in the range of 50–300 K are carried out to study positronium formation in 40 KeV B+-ion implanted polymethylmethacrylate (B:PMMA) with two ion doses of 3.13 × 1015 and 3.75 × 1016 ions/cm2. The investigated samples show the various temperature trends of ortho-positronium (o-Ps) lifetime τ3 and intensity I3 in PMMA before and after ion implantation. Two transitions in the vicinity of ∼150 and ∼250 K, ascribed to γ and β transitions, respectively, are observed in the PMMA and B:PMMA samples in consistent with reference data for pristine sample. The obtained results are compared with room temperature PALS study of PMMA with different molecular weight (Mw) which known from literature. It is found that B+-ion implantation leads to decreasing Mw in PMMA at lower ion dose. At higher ion dose the local destruction of polymeric structure follows to broadening of lifetime distribution (hole size distribution).
Predicting proton titration in cationic micelle and bilayer environments
Authors: Morrow Brian H. , Eike David M. , Murch Bruce P. , Koenig Peter H. , Shen Jana K.
Published: September 2014

Knowledge of the protonation behavior of pH-sensitive molecules in micelles and bilayers has significant implications in consumer product development and biomedical applications. However, the calculation of pKa’s in such environments proves challenging using traditional structure-based calculations. Here we apply all-atom constant pH molecular dynamics with explicit ions and titratable water to calculate the pKa of a fatty acid molecule in a micelle of dodecyl trimethylammonium chloride and liquid as well as gel-phase bilayers of diethyl ester dimethylammonium chloride. Interestingly, the pKa of the fatty acid in the gel bilayer is 5.4, 0.4 units lower than that in the analogous liquid bilayer or micelle, despite the fact that the protonated carboxylic group is significantly more desolvated in the gel bilayer. This work illustrates the capability of all-atom constant pH molecular dynamics in capturing the delicate balance in the free energies of desolvation and Coulombic interactions. It also shows the importance of the explicit treatment of ions in sampling the protonation states. The ability to model dynamics of pH-responsive substrates in a bilayer environment is useful for improving fabric care products as well as our understanding of the side effects of anti-inflammatory drugs.
Intrinsic low pass filtering improves signal-to-noise ratio in critical-point flexure biosensors
Authors: Jain Ankit , Alam Muhammad Ashraful
Published: September 2014

A flexure biosensor consists of a suspended beam and a fixed bottom electrode. The adsorption of the target biomolecules on the beam changes its stiffness and results in change of beam's deflection. It is now well established that the sensitivity of sensor is maximized close to the pull-in instability point, where effective stiffness of the beam vanishes. The question: “Do the signal-to-noise ratio (SNR) and the limit-of-detection (LOD) also improve close to the instability point?”, however remains unanswered. In this article, we systematically analyze the noise response to evaluate SNR and establish LOD of critical-point flexure sensors. We find that a flexure sensor acts like an effective low pass filter close to the instability point due to its relatively small resonance frequency, and rejects high frequency noise, leading to improved SNR and LOD. We believe that our conclusions should establish the uniqueness and the technological relevance of critical-point biosensors.
Room-temperature magnetoelectric coupling in nanocrystalline Na0.5Bi0.5TiO3
Authors: Ju Lin , Shi Changmin , Sun Li , Zhang Yongjia , Qin Hongwei , Hu Jifan
Published: September 2014

Nanocrystalline Na0.5Bi0.5TiO3 was prepared by sol-gel method. The nanocrystalline Na0.5Bi0.5TiO3 plates present room temperature ferromagnetism (FM). The reduction of FM for the plate with subsequent long time and high temperature air-annealing indicating that the observed ferromagnetism is connected with the vacancies at/near the surface of nanograins. For Na0.5Bi0.5TiO3 powders after annealing at 900 °C in air, a subsequent annealing in vacuum at 900 °C for 20 min weakens the room-temperature FM, but a subsequent annealing in oxygen atmosphere at 900 °C for 20 min enhances the room-temperature FM, which means that the observed FM in nanocrystalline Na0.5Bi0.5TiO3 may originate from cation vacancy at/near the surface of nanograins. The results of density functional theory calculation with the local density approximation plus on-site effect (LDA + U) method on the magnetism of Na0.5Bi0.5TiO3 (100) surface show that Na vacancies can introduce a nonzero magnetic moment. The Na0.5Bi0.5TiO3 plates annealed at 900 °C for 1 h present d0 multiferroicity with the coexistence of ferromagnetism and ferroelectricity at room temperature. The room-temperature magnetodielectric effect was observed in Na0.5Bi0.5TiO3 plates. In addition, the electric field treatment leads to an enormous enhancement of saturation magnetization for Na0.5Bi0.5TiO3 multiferroic plate, showing a strong magnetoelectric coupling.
Dielectric constant and low-frequency infrared spectra for liquid water and ice Ih within the E3B model
Authors: Shi L. , Ni Y. , Drews S. E. P. , Skinner J. L.
Published: September 2014

Two intrinsic difficulties in modeling condensed-phase water with conventional rigid non-polarizable water models are: reproducing the static dielectric constants for liquid water and ice Ih, and generating the peak at about 200 cm−1 in the low-frequency infrared spectrum for liquid water. The primary physical reason for these failures is believed to be the missing polarization effect in these models, and consequently various sophisticated polarizable water models have been developed. However, in this work we pursue a different strategy and propose a simple empirical scheme to include the polarization effect only on the dipole surface (without modifying a model's intermolecular interaction potential). We implement this strategy for our explicit three-body (E3B) model. Our calculated static dielectric constants and low-frequency infrared spectra are in good agreement with experiment for both liquid water and ice Ih over wide temperature ranges, albeit with one fitting parameter for each phase. The success of our modeling also suggests that thermal fluctuations about local minima and the energy differences between different proton-disordered configurations play minor roles in the static dielectric constant of ice Ih. Our analysis shows that the polarization effect is important in resolving the two difficulties mentioned above and sheds some light on the origin of several features in the low-frequency infrared spectra for liquid water and ice Ih.
A molecular dynamics study of intramolecular proton transfer reaction of malonaldehyde in solutions based upon mixed quantum-classical approximation. I. Proton transfer reaction in water
Authors: Yamada Atsushi , Kojima Hidekazu , Okazaki Susumu
Published: September 2014

In order to investigate proton transfer reaction in solution, mixed quantum-classical molecular dynamics calculations have been carried out based on our previously proposed quantum equation of motion for the reacting system [A. Yamada and S. Okazaki, J. Chem. Phys. 128, 044507 (2008)]. Surface hopping method was applied to describe forces acting on the solvent classical degrees of freedom. In a series of our studies, quantum and solvent effects on the reaction dynamics in solutions have been analysed in detail. Here, we report our mixed quantum-classical molecular dynamics calculations for intramolecular proton transfer of malonaldehyde in water. Thermally activated proton transfer process, i.e., vibrational excitation in the reactant state followed by transition to the product state and vibrational relaxation in the product state, as well as tunneling reaction can be described by solving the equation of motion. Zero point energy is, of course, included, too. The quantum simulation in water has been compared with the fully classical one and the wave packet calculation in vacuum. The calculated quantum reaction rate in water was 0.70 ps−1, which is about 2.5 times faster than that in vacuum, 0.27 ps−1. This indicates that the solvent water accelerates the reaction. Further, the quantum calculation resulted in the reaction rate about 2 times faster than the fully classical calculation, which indicates that quantum effect enhances the reaction rate, too. Contribution from three reaction mechanisms, i.e., tunneling, thermal activation, and barrier vanishing reactions, is 33:46:21 in the mixed quantum-classical calculations. This clearly shows that the tunneling effect is important in the reaction.
Understanding the Kondo resonance in the d-CoPc/Au(111) adsorption system
Authors: Wang Yu , Zheng Xiao , Li Bin , Yang Jinlong
Published: September 2014

By combining the density functional theory (DFT) and a hierarchical equations of motion (HEOM) approach, we investigate the Kondo phenomena in a composite system consisting of a dehydrogenated cobalt phthalocyanine molecule (d-CoPc) adsorbed on an Au(111) surface. DFT calculations are performed to determine the ground-state geometric and electronic structures of the adsorption system. It is found that the singly occupied \documentclass[12pt]{minimal}\begin{document}$d_{z^2}$\end{document}dz2 orbital of Co forms a localized spin, which could be screened by the substrate conduction electrons. This screening leads to the prominent Kondo features as observed in the scanning tunneling microscopy experiments. We then employ the HEOM approach to characterize the Kondo correlations of the adsorption system. The calculated temperature-dependent differential conductance spectra and the predicted Kondo temperature agree well with the experiments, and the universal Kondo scaling behavior is correctly reproduced. This work thus provides important insights into the relevant experiments, and it also highlights the applicability of the combined DFT+HEOM approach to the studies of strongly correlated condensed matter systems.
Enhanced interaction between a mechanical oscillator and two coupled resonant electrical circuits
Authors: Dmitriev A. V. , Mitrofanov V. P.
Published: September 2014

This paper reports result of calculation and experimental realization of an electromechanical system that consists of a high-Q mechanical oscillator parametrically coupled in the manner of a capacitive transducer with a radio frequency (RF) circuit, which is in turn inductively coupled with another RF circuit. The system operates in the resolved sideband regime when the mechanical oscillator's frequency is larger than the electrical circuits' bandwidths. Using two coupled RF circuits allowed one to enhance the interaction between them and the mechanical oscillator which is one of flexural vibrational modes of a free-edge circular silicon wafer. Such a coupled electromechanical system can be used as a high-sensitive capacitive vibration sensor.
Design of a Doppler reflectometer for KSTAR
Authors: Lee K. D. , Nam Y. U. , Seo Seong-Heon , Kim Y. S.
Published: September 2014

A Doppler reflectometer has been designed to measure the poloidal propagation velocity on the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. It has the operating frequency range of V-band (50-75 GHz) and the monostatic antenna configuration with extraordinary mode (X-mode). The single sideband modulation with an intermediate frequency of 50 MHz is used for the heterodyne measurement with the 200 MHz in-phase and quadrature (I/Q) phase detector. The corrugated conical horn antenna is used to approximate the Gaussian beam propagation and it is installed together with the oversized rectangular waveguides in the vacuum vessel. The first commissioning test of the Doppler reflectometer system on the KSTAR tokamak is planned in the 2014 KSTAR experimental campaign.
Physical interpretation of Jeans instability in quantum plasmas
Authors: Akbari-Moghanjoughi M.
Published: September 2014

In this paper, we use the quantum hydrodynamics and its hydrostatic limit to investigate the newly posed problem of Jeans instability in quantum plasmas from a different point of view in connection with the well-known Chandrasekhar mass-limit on highly collapsed degenerate stellar configurations. It is shown that the hydrodynamic stability of a spherically symmetric uniform quantum plasma with a given fixed mass is achieved by increase in its mass-density or decrease in the radius under the action of gravity. It is also remarked that for masses beyond the limiting Jeans-mass, the plasma becomes completely unstable and the gravitational collapse would proceed forever. This limiting mass is found to depend strongly on the composition of the quantum plasma and the atomic-number of the constituent ions, where it is observed that heavier elements rather destabilize the quantum plasma hydrodynamically. It is also shown that the Chandrasekhar mass-limit for white dwarf stars can be directly obtained from the hydrostatic limit of our model.
Reference hypernetted chain theory for ferrofluid bilayer: Distribution functions compared with Monte Carlo
Authors: Polyakov Evgeny A. , Vorontsov-Velyaminov Pavel N.
Published: September 2014

Properties of ferrofluid bilayer (modeled as a system of two planar layers separated by a distance h and each layer carrying a soft sphere dipolar liquid) are calculated in the framework of inhomogeneous Ornstein-Zernike equations with reference hypernetted chain closure (RHNC). The bridge functions are taken from a soft sphere (1/r12) reference system in the pressure-consistent closure approximation. In order to make the RHNC problem tractable, the angular dependence of the correlation functions is expanded into special orthogonal polynomials according to Lado. The resulting equations are solved using the Newton-GRMES algorithm as implemented in the public-domain solver NITSOL. Orientational densities and pair distribution functions of dipoles are compared with Monte Carlo simulation results. A numerical algorithm for the Fourier-Hankel transform of any positive integer order on a uniform grid is presented.
Schottky-type surface plasmon detector with nano-slit grating using enhanced resonant optical transmission
Authors: Takeda Ayumi , Aihara Takuma , Fukuhara Masashi , Ishii Yuya , Fukuda Mitsuo
Published: September 2014

We propose a metal nano-slit structure to enhance the surface plasmon (SP) intensity at the Au/Si interface between a gold film and a silicon substrate. By tuning the phase conditions to be in anti-phase interference at the air/Au interface and in in-phase interference at the Au/Si interface, the SP intensity at the Au/Si interface was enhanced. This structure was numerically designed using the finite-difference time-domain method and was experimentally confirmed by monitoring of the photocurrent of an Au/Si Schottky-type SP detector. This design, with its two phase matching conditions that enhance the SP intensity at the Au/Si interface, was applied to a ring-type metal grating on a silicon substrate, and demonstrated the photocurrent enhancement.
Elastic constants determined by nanoindentation for p-type thermoelectric half-Heusler
Authors: Gahlawat S. , He R. , Chen S. , Wheeler L. , Ren Z. F. , White K. W.
Published: September 2014

This paper presents a study of the elastic properties of the p-type thermoelectric half-Heusler material, Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2, using nanoindentation. Large grain-sized polycrystalline specimens were fabricated for these measurements, providing sufficient indentation targets within single grains. Electron Backscatter Diffraction methods indexed the target grains for the correlation needed for our elastic analysis of individual single crystals for this cubic thermoelectric material. Elastic properties, including the Zener ratio and the Poisson ratio, obtained from the elasticity tensor are also reported.
Low temperature magnetic phase transition and interlayer coupling in double-wall carbon nanotubes
Authors: Diamantopoulou A. , Glenis S. , Likodimos V. , Guskos N.
Published: September 2014

The magnetic properties of double wall carbon nanotubes (DWCNTs) were investigated using electron spin resonance (ESR) spectroscopy. An asymmetric resonance line of low intensity was identified and analyzed by the superimposition of a narrow and a broad metallic lineshape, attributed to the distinct contributions of defect spins located on the inner and outer DWCNTs shells. The spin susceptibilities of both ESR components revealed a ferromagnetic phase transition at low temperatures (T < 10 K) with small variation in the corresponding Curie-Weiss temperatures, approaching closely that of metallic single wall carbon nanotubes. Interlayer coupling between the DWCNT layers is suggested to effectively reduce the difference between the transition temperatures for the inner and outer shells and enhance spin-spin interactions between defect spins via the RKKY-type interaction of localized spins with conduction electrons.
Irreversible transitions in the exchange-striction model of spin-glass state
Authors: Valkov V. I. , Golovchan A. V.
Published: September 2014

Based on the assumption of a negative volume dependence of random exchange integrals, it is possible to switch to a compressible Sherrington–Kirkpatrick spin-glass model. Within the proposed model, temperature–pressure phase diagrams were calculated and pressure- and magnetic-field-induced first-order phase transitions from the initial paramagnetic and spin-glass states to the ferromagnetic state were predicted. It was shown that the application of pressure in the spin-glass state not only increases and shifts magnetic susceptibility, but also reduces the critical magnetic fields of irreversible induced phase transitions from the spin-glass to the ferromagnetic state. The obtained results are used to describe the spin-glass state in (Sm1–xGdx)0.55Sr0.45MnO3.
Optical and magnetoresistive properties of polycrystalline La0.7Sr0.3MnO3 films on crystalline Al2O3 and Gd3Ga5O12 substrates
Authors: Tikhii A. A. , Gritskih V. A. , Kara-Murza S. V. , Korchikova N. V. , Nikolaenko Yu. M. , Revenko Yu. F. , Reshidova I. Yu. , Zhikharev I. V.
Published: September 2014

The influence of thickness and heat treatment on the optical, magnetic and magnetoresistive properties of polycrystalline La0.7Sr0.3MnO3 (LSMO) films deposited onto Al2O3 (012) and Gd3Ga5O12 (111) crystalline substrates was investigated. It was shown that the optical properties of the annealed films are similar in the investigated range of photon energies 1–6 eV, independently of their thickness and substrate material. The optical conductivity spectra of the annealed films exhibit the same structure as epitaxial LSMO films but shifted to higher energies by ∼0.5 eV. The temperatures of broadened metal–insulator and ferromagnetic–paramagnetic transitions in the LSMO films are size-dependent and considerably lower as compared with the epitaxial films. The magnetoresistive effect is ∼15% in the field of 10 kOe and at the temperature of metal-insulator transition. These features of the films under study are explained by the presence of grain boundaries and the influence of the film-substrate interface.
Effect of pressure on the critical temperature of single-crystal Y0.95Pr0.05Ba2Cu3O7–δ with a specified planar defect geometry
Authors: Khadzhai G. Ya. , Sclyar V. V. , Vovk R. V. , Dovhopolova Ya. V. , Chornovol-Tkachenko O. O.
Published: September 2014

The effect of high hydrostatic pressures up to 17 kbar on the conductivity in the basal ab-plane of single crystal samples of Y1–xPrxBa2Cu3O7–δ with a system of unidirectional twin boundaries and lightly doped with praseodymium (x = 0.05) is studied. It is found that, in contrast with undoped YBa2Cu3O7-δ samples with an optimum oxygen content, high pressure leads to a double increase in the pressure derivative dTc/dP. Possible mechanisms for the effect of high pressure on Tc are discussed taking the existence of singularities in the carrier electronic spectrum into account.
Effect of deformation-thermal processing using equal-channel multiangle pressing and low-temperature drawing on the superconducting properties of niobium-titanium alloys
Authors: Beloshenko V. A. , Dmitrenko V. Yu. , Chishko V. V. , Sokolenko V. I. , Volchok O. I.
Published: September 2014

The effect of combined deformation, including equal-channel multiangle pressing (ECMAP), low-temperature (77 K) drawing, and thermal processing, on the critical current density of superconducting wires based on Nb-Ti alloys is investigated. Reasonable parameters are established for deformation-thermal processing of NT-50 alloy using ECMAP that will ensure improved functionality of superconductors based on this alloy. Vortex pinning on structural inhomogeneities of these alloys is analyzed qualitatively.
Suppression of transparency of thin modulated slabs of layered superconductors in the terahertz frequency range
Authors: Kadygrob D. V. , Yampol'skii V. A.
Published: September 2014

A reduction in the transmission of terahertz radiation through a periodically modulated slab of layered superconductor owing to diffraction of the incident wave and resonance excitation of eigenmodes is predicted and studied theoretically. The slab thickness is assumed to be much less than the skin depth and when there is no modulation the slab transmission is close to unity.
EPR of Dy3+ ions in YAl3(BO3)4 and EuAl3(BO3)4 aluminoborates
Authors: Prokhorov A. D. , Prokhorov A. A. , Zubov E. E. , Chernysh L. F. , Dyakonov V. , Szymczak H.
Published: September 2014

The EPR spectra of impurity Dy3+ ions in YAl3(BO3)4 and EuAl3(BO3)4 aluminoborates were investigated. The signals from the ground and excited doublets were observed and the g-factors and the hyperfine interaction constants were determined. From the temperature dependence of the signal intensity of the excited doublet, the energy distances between the ground and excited doublets were obtained as (3.26 ± 0.13) cm–1 and (2.54 ± 0.16) cm–1 for YAl3(BO3)4 and EuAl3(BO3)4, respectively. A broadening of the absorption line with increasing temperature is related with the strong spin-phonon interaction and is described by the Orbach–Aminov process via the excited doublet. It was found that the decrease in g-factor is caused by the spin-phonon interaction.
Electromagnetic model for near-field microwave microscope with atomic resolution: Determination of tunnel junction impedance
Authors: Reznik Alexander N.
Published: September 2014

An electrodynamic model is proposed for the tunneling microwave microscope with subnanometer space resolution as developed by Lee et al. [Appl. Phys. Lett. 97, 183111 (2010)]. Tip-sample impedance Za was introduced and studied in the tunneling and non-tunneling regimes. At tunneling breakdown, the microwave current between probe and sample flows along two parallel channels characterized by impedances Zp and Zt that add up to form overall impedance Za. Quantity Zp is the capacitive impedance determined by the near field of the probe and Zt is the impedance of the tunnel junction. By taking into account the distance dependences of effective tip radius r0(z) and tunnel resistance Rt(z) = Re[Zt(z)], we were able to explain the experimentally observed dependences of resonance frequency fr(z) and quality factor QL(z) of the microscope. The obtained microwave resistance Rt(z) and direct current tunnel resistance Rtdc(z) exhibit qualitatively similar behavior, although being largely different in both magnitude and the characteristic scale of height dependence. Interpretation of the microwave images of the atomic structure of test samples proved possible by taking into account the inductive component of tunnel impedance ImZt = ωLt. Relation ωLt/Rt ≈ 0.235 was obtained.