bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of chiral cyclobutanes via rhodium/diene-catalyzed asymmetric 1,4-addition: a dramatic ligand effect on the diastereoselectivity
Authors: Chen Ya-Jing , Hu Tian-Jiao , Feng Chen-Guo , Lin Guo-Qiang
Published: April 2015

A highly diastereo- and enantioselective rhodium-catalyzed arylation of cyclobutene-1-carboxylate esters for the efficient synthesis of chiral cyclobutanes has been developed.
Silver-catalyzed Meerwein arylation: intermolecular and intramolecular fluoroarylation of styrenes
Authors: Guo Rui , Yang Haodong , Tang Pingping
Published: April 2015

The first example of silver-catalyzed intermolecular and intramolecular Meerwein fluoroarylation of styrenes with aryl diazonium salts was reported.
Size-dependent penetration of carbon dots inside the ferritin nanocages: evidence for the quantum confinement effect in carbon dots
Authors: Bhattacharya Arpan , Chatterjee Surajit , Prajapati Roopali , Mukherjee Tushar Kanti
Published: April 2015

Size-dependent penetration of CDs through the ferritin channels has been successfully demonstrated by means of λex-dependent PL quenching of CDs by the Fe3+ ions of ferritin.
Giant conductivity enhancement of ferrite insulators induced by atomic hydrogen
Authors: Xiang Qing-Yun , Wang Yu , Li Shi-Yu , Wang Lan-Hua , Mo Li-Bin , Yao Wen-Qing , Zhang Li , Cao Jiang-Li
Published: April 2015

Large conductivity enhancements in ferrite induced by atomic hydrogen and kinetics correlations between the adsorption of atomic hydrogen, hydrogen incorporation and conductivity enhancement are established.
Au–Ag nanoalloy molecule-like clusters for enhanced quantum efficiency emission of Er3+ions in silica
Authors: Cesca Tiziana , Kalinic Boris , Michieli Niccolò , Maurizio Chiara , Trapananti Angela , Scian Carlo , Battaglin Giancarlo , Mazzoldi Paolo , Mattei Giovanni
Published: April 2015

(Au–Ag)Nnanoalloy clusters made up ofN= 10–15 atoms increase by an order of magnitude the room temperature photoemission intensity of Er3+in silica, better than monometallic AuNclusters of the same size.
Recent advances in the synthesis of nitrogen heterocycles via radical cascade reactions using isonitriles as radical acceptors
Authors: Zhang Bo , Studer Armido
Published: April 2015

Radical isonitrile insertion reactions are highly valuable for the construction of N-containing heterocycles such as phenanthridines, quinolines, isoquinolines, quinoxalines and indoles.
The synthesis and characterisation of coordination and hydrogen-bonded networks based on 4-(3,5-dimethyl-1H-pyrazol-4-yl)benzoic acid
Authors: Bryant Macguire R. , Burrows Andrew D. , Fitchett Christopher M. , Hawes Chris S. , Hunter Sally O. , Keenan Luke L. , Kelly David J. , Kruger Paul E. , Mahon Mary F. , Richardson Christopher
Published: April 2015

A variety of coordination materials are formed from the heteroditopic ligand 4-(3,5-dimethyl-1H-pyrazol-4-yl)benzoate.
Targeted design of a cubic boron imidazolate cage with sensing and reducing functions
Authors: Zhang De-Xiang , Zhang Hai-Xia , Wen Tian , Zhang Jian
Published: April 2015

A cubic cationic cage is rationally designed by using tridentate boron-imidazolate ligands to link tetrahedral metal Zn(ii) centers, which displays excellent properties in the Cr2O72− exchange and can reduce Au3+ ions into Au nanoparticles directly.
Anionic coordination complexes of C60 and C70 with cyclopentadienyl and pentamethylcyclopentadienyl molybdenum dicarbonyl
Authors: Konarev Dmitri V. , Kuzmin Alexey V. , Troyanov Sergey I. , Nakano Yoshiaki , Khasanov Salavat S. , Otsuka Akihiro , Yamochi Hideki , Saito Gunzi , Lyubovskaya Rimma N.
Published: April 2015

Crystalline molybdenum η2-complexes with fullerenes C60 and C70 in the neutral and negatively charged form were obtained and studied.
Synthesis and catalytic application of magnesium complexes bearing pendant indolyl ligands
Authors: Peng Kuo-Fu , Chen Yun , Chen Chi-Tien
Published: April 2015

A family of magnesium pendant indolyl complexes has been prepared and it exhibited high activities towards the ROP of cyclic esters in the presence of benzyl alcohol.
Large-scale delamination of multi-layers transition metal carbides and carbonitrides “MXenes”
Authors: Naguib Michael , Unocic Raymond R. , Armstrong Beth L. , Nanda Jagjit
Published: April 2015

Large-scale delamination of MXenes was achieved by using a simple aqueous organic base treatment followed by agitation in water.
Synthesis of mesoporous nanocomposites for their application in solid oxide electrolysers cells: microstructural and electrochemical characterization
Authors: Torrell M. , Almar L. , Morata A. , Tarancón A.
Published: April 2015

Fabrication routes for new SOEC mesoporous nanocomposite materials as electrodes are presented in this paper. NiO–CGO and SDC–SSC are described as possible new materials and their synthesis and the cell fabrication are discussed. The obtained materials are microstructurally characterised by SEM, TEM and XRD, where the mesoporous structures are observed and analysed. The obtained samples are electrochemically analysed by I–V polarisation curves and EIS analysis, showing a maximum current density of 330 mA cm−2 at 1.7 V. A degradation of the cell performance is evidenced after a potentiostatic test at 1.4 V after more than 40 hours. Oxygen electrode delaminating is detected, which is most probably the main cause of ageing. Even taking into account the lack of durability of the fabricated cells, the mesoporous electrodes do not seem to be altered, opening the possibility for further studies devoted to this high stability material for SOEC electrodes.
Platycodin D isolated from the aerial parts of Platycodon grandiflorum protects alcohol-induced liver injury in mice
Authors: Li Wei , Liu Ying , Wang Zi , Han Ye , Tian Yu-Hong , Zhang Gui-Shan , Sun Yin-Shi , Wang Ying-Ping
Published: April 2015

Platycodin D (PD) is the main active saponin ofPlatycodon grandiflorum(PG) and is reported to exhibit multiple biological effects, including anti-tumor, anti-inflammation, and anti-obesity properties.
Yulangsan polysaccharide improves redox homeostasis and immune impairment in d-galactose-induced mimetic aging
Authors: Doan Van Minh , Chen Chunxia , Lin Xing , Nguyen Van Phuc , Nong Zhihuan , Li Weisi , Chen Qingquan , Ming Jianjun , Xie Qiuqiao , Huang Renbin
Published: April 2015

Yulangsan polysaccharide (YLSP) is a traditional Chinese medicine used in long-term treatment as a modulator of brain dysfunction and immunity.
Direct detection and drug-resistance profiling of bacteremias using inertial microfluidics
Authors: Hou Han Wei , Bhattacharyya Roby P. , Hung Deborah T. , Han Jongyoon
Published: April 2015

Isolation of low-abundance bacteria from whole blood for direct pathogen identification and antibiotic susceptibility determination using hybridization-based RNA detection.
Target specific proteochemometric model development for BACE1 – protein flexibility and structural water are critical in virtual screening
Authors: Manoharan Prabu , Chennoju Kiranmai , Ghoshal Nanda
Published: April 2015

Structural water and protein plasticity are important factors for BACE1 targeted ligand virtual screening.
Direct conversion of allyl arenes to aryl ethylketones via a TBHP-mediated palladium-catalyzed tandem isomerization–Wacker oxidation of terminal alkenes
Authors: Zhao JinWu , Liu Li , Xiang ShiJian , Liu Qiang , Chen HuoJi
Published: April 2015

A TBHP-mediated palladium-catalyzed tandem isomerization–Wacker oxidation of terminal alkenes was developed.
A predictive mass transport model for gas separation using glassy polymer membranes
Authors: Shoghl Sina Nabati , Raisi Ahmadreza , Aroujalian Abdolreza
Published: April 2015

The NELF model was used for estimating gas sorption in non-equilibrium glassy polymers and a predictive mass transfer model was developed.
Deep eutectic solvent: a simple, environmentally benign reaction media for regioselective synthesis of 2,3,4-trisubstituted 1H-pyrroles
Authors: Kalmode Hanuman P. , Vadagaonkar Kamlesh S. , Murugan Kaliyappan , Prakash Sattey , Chaskar Atul C.
Published: April 2015

A greener, rapid and highly efficient synthetic protocol for the construction of pyrroles has been achieved.
Unravelling the mechanism of the ketene-imine Staudinger reaction. An ELF quantum topological analysis
Authors: Domingo Luis R. , Ríos-Gutiérrez Mar , Sáez José A.
Published: April 2015

The mechanism and stereoselectivity of the ketene-imine Staudinger reaction have been studied using DFT methods.
Asymmetric supercapacitor based on an α-MoO3 cathode and porous activated carbon anode materials
Authors: Barzegar F. , Bello A. , Momodu D. Y. , Dangbegnon J. K. , Taghizadeh F. , Madito M. J. , Masikhwa T. M. , Manyala N.
Published: April 2015

Low cost porous carbon materials were produced from cheap polymer materials and graphene foam materials which were tested as a negative electrode material in an asymmetric cell configuration with α-MoO3 as a positive electrode.
Synthetic preparation of novel 3D Si/TiO2–Ti2O3 composite nanorod arrays as anodes in lithium ion batteries
Authors: Zhong Yuan , Yue Chuang , Chen Binbin , Sun Shibo , Zheng Mingsen , Zhao Libo , Wu Suntao , Li Jing , Kang Junyong , Lin Liwei
Published: April 2015

A novel 3D Si/TiO2–Ti2O3 nanorod array composite prepared by a solvothermal method used as anode in Li-ion batteries.
Base promoted direct C4-arylation of 4-substituted-pyrazolin-5-ones with diaryliodonium salts
Authors: Mao Song , Geng Xu , Yang Yang , Qian Xiaofei , Wu Shengying , Han Jianwei , Wang Limin
Published: April 2015

A metal-free approach for the C4-arylation of 4-substituted-pyrazolin-5-ones with diaryliodonium salts was developed.
The corrosion inhibition effect of aryl pyrazolo pyridines on copper in hydrochloric acid system: computational and electrochemical studies
Authors: Sudheer Sudheer , Quraishi M. A.
Published: April 2015

The inhibition effect of three aryl pyrazole pyridine derivatives (APPs) against the corrosion of copper in 0.5 M HCl has been investigated by electrochemical impedance, potentiodynamic polarization measurements and quantum chemical methods.
Design and optimization of clotrimazole–hydroxypropyl-β-cyclodextrin bioadhesive vaginal tablets using Anacardium occidentale gum by 32 factorial design
Authors: Hani Umme , Krishna Gokul , Shivakumar H. G.
Published: April 2015

Clotrimazole (CTZ), a BCS class II drug, is widely employed in the treatment of vaginal candidiasis.
A Geobacter strain isolated from rice paddy soil with higher bioelectricity generation capability in comparison to Geobacter sulfurreducens PCA
Authors: Deng Dandan , Zhang Yichi , Liu Ying
Published: April 2015

A novel electrochemically active strain D-8 was successfully isolated from rice paddy soil. The strain D-8 can use more carbon sources and show higher current density thanG. sulfurreducensPCA. It might be a promising bioanodic organism in MFCs.
Correction: Hybrid composites: amalgamation of proteins with polymeric phenols as a multifunctional material for leather processing
Authors: Ramalingam Sathya , Janardhanan Sreeram Kalarical , Raghava Rao Jonnalagadda , Unni Nair Balachandran
Published: April 2015

Correction for ‘Hybrid composites: amalgamation of proteins with polymeric phenols as a multifunctional material for leather processing’ by Sathya Ramalingam et al., RSC Adv., 2015, 5, 33221–33232.
Doping-induced memory effect in Li-ion batteries: the case of Al-doped Li4Ti5O12
Authors: Li De , Sun Yang , Liu Xizheng , Peng Ruwen , Zhou Haoshen
Published: April 2015

A memory effect in Li-ion batteries can be induced and tailored by element doping, such as Al-doping in spinel Li4Ti5O12.
Can acyclic conformational control be achieved via a sulfur–fluorine gauche effect?
Authors: Thiehoff C. , Holland M. C. , Daniliuc C. , Houk K. N. , Gilmour R.
Published: April 2015

Herein detailed conformational analyses of β-fluorosulfides, -sulfoxides and -sulfones are disclosed, thus extending the scope of the fluorine gauche effect to the 3rd Period (X = SR, SOR, SO2R; ϕFCCS ≈ 60°).
Efficient photocatalytic dechlorination of chlorophenols over a nonlinear optical material Na3VO2B6O11 under UV-visible light irradiation
Authors: Fan Xiaoyun , Lai Kangrong , Wang Lichang , Qiu Hengshan , Yin Jiao , Zhao Pengjun , Pan Shilie , Xu Jinbao , Wang Chuanyi
Published: April 2015

One type of nonlinear material, Na3VO2B6O11 (NVB), demonstrates 90 times higher photocatalytic efficiency than that of the commercial P25 in the dechlorination of 2,4-DCP under UV-vis light irradiation.
Co3ZnC core–shell nanoparticle assembled microspheres/reduced graphene oxide as an advanced electrocatalyst for hydrogen evolution reaction in an acidic solution
Authors: Ma Lianbo , Shen Xiaoping , Zhu Jun , Zhu Guoxing , Ji Zhenyuan
Published: April 2015

A novel Co3ZnC/RGO composite with excellent electrocatalytic activity toward HER was prepared through an effective two-step strategy.
A Si/Ge nanocomposite prepared by a one-step solid-state metathesis reaction and its enhanced electrochemical performance
Authors: Lin Ning , Wang Liangbiao , Zhou Jianbin , Zhou Jie , Han Ying , Zhu Yongchun , Qian Yitai , Cao Changhe
Published: April 2015

High-performance Si/Ge anodes are prepared through a one-step solid-state metathesis reaction between Mg2Si and GeO2 for the first time.
The Efficacy of Routine Screening for High-Frequency Hearing Loss in Adults and Children
Authors: Serpanos Yula C. , Senzer Deborah , Renne Brittany , Langer Rebecca , Hoffman Roxanne
Published: April 2015

Purpose

This study was conducted to investigate the efficacy of routine screening for high-frequency hearing loss (HFHL) including 3000, 6000, and 8000 Hz frequencies with conventional test frequencies (1000, 2000, and 4000 Hz) in adults and children in a university outreach program.

Method

Screening outcomes were examined in 2 cohorts of adults (Cohort 1,
N
= 315,
M
= 66.2 years; Cohort 2,
N
= 67,
M
= 68.3 years) and children (Cohort 1,
N
= 177,
M
= 6.5 years; Cohort 2,
N
= 57,
M
= 6.9 years) with a high-frequency screen protocol (1000–8000 Hz at 25 dB HL for adults and 20 dB HL for children) using supra-aural headphones. A rescreen was conducted in Cohort 2 with a modified protocol using insert earphones and monitored ambient noise levels.

Results

Average total test time significantly increased (
p
< .0001) and nearly doubled with inclusion of 3000-, 6000-, and 8000-Hz frequencies, adding approximately 1 min. Rescreen referral rates decreased by approximately 2%–16% at 1000–8000 Hz (approximately 13%–16% at 6000 and 8000 Hz) using the modified protocol in adults and children, supporting false-positive responses using supra-aural headphones.

Conclusion

Screening for HFHL should include insert earphones in order to prevent potential errors, particularly at 6000 and 8000 Hz.
The Development of the Mealings, Demuth, Dillon, and Buchholz Classroom Speech Perception Test
Authors: Mealings Kiri T. , Demuth Katherine , Buchholz Jörg , Dillon Harvey
Published: April 2015

Purpose

Open-plan classroom styles are increasingly being adopted in Australia despite evidence that their high intrusive noise levels adversely affect learning. The aim of this study was to develop a new Australian speech perception task (the Mealings, Demuth, Dillon, and Buchholz Classroom Speech Perception Test) and use it in an open-plan classroom to assess how intrusive noise affects speech perception.

Method

The first part of this article describes how the online 4-picture choice speech perception task materials were created. The second part focuses on the study involving twenty-two 5- to 6-year-old children in an open-plan classroom who completed the task while other classes engaged in quiet and noisy activities.

Results

Children's performance accuracy, number of responses, and speed were lower in the noisy condition compared with the quiet condition. In addition, children's speech perception scores decreased the farther away they were seated from the loudspeaker. Overall, the children understood and were engaged in the task, demonstrating that it is an appropriate tool for assessing speech perception live in the classroom with 5- to 6-year-old children.

Conclusions

The results suggest that the Mealings, Demuth, Dillon, and Buchholz Classroom Speech Perception Test is a helpful tool for assessing speech perception in classrooms and that it would be beneficial to use in future research investigating how classroom design and noise affect speech perception.
75 GBd InP‐HBT MUX‐DAC module for high‐symbol‐rate optical transmission
Authors: Nagatani M. , Wakita H. , Nosaka H. , Kurishima K. , Ida M. , Sano A. , Miyamoto Y.
Published: April 2015

An ultra‐broadband 6 bit digital‐to‐analogue converter (DAC) has been designed and fabricated in InP‐HBT technology. The DAC IC includes six 2:1 MUXs and thus operates with a half‐rate clock. The DAC module is equipped with 1 mm connectors for its analogue output to ensure broadband characteristics. The measured analogue output bandwidth (BW) is >40 GHz. Four‐level pulse amplitude modulation signals with clear eye openings were measured at symbol rates of up to 75 GBd. This MUX‐DAC module has the widest BW of any previously reported DACs and is suitable for high‐symbol‐rate optical transmitters.
Formation osseuse et corticotomies à visée de facilitation métabolique : existe-t-il une ostéogénèse induite par les corticotomies alvéolaires ?
Authors: Moreau Nathan , Charrier Jean-Baptiste
Published: April 2015

L’évolution des thérapeutiques orthodontiques doit faire face à une demande croissante de traitements plus courts pour un même résultat final, en particulier chez les patients adultes. Ces dernières années, l’amélioration des techniques orthodontiques, des techniques chirurgicales et anesthésiques en chirurgie orthognathique ont permis un développement considérable des protocoles orthodontico-chirurgicaux et de la prise en charge orthodontique chez le patient adulte. Les corticotomies alvéolaires font partie de ces nouvelles techniques. Elles permettent une facilitation des déplacements dentaires orthodontiques en modifiant localement le métabolisme osseux et en favorisant une ostéopénie transitoire, facilitatrice du mouvement dentaire. Elles augmentent ainsi l’enveloppe des mouvements dentaires possibles avec les techniques conventionnelles. Bien que la littérature récente apporte une meilleure compréhension des effets biologiques des corticotomies, il n’existe que peu d’informations sur le pouvoir ostéogénique de celles-ci. À travers un cas clinique et une revue de la littérature concernant cette technique et ses principes biologiques, nous décrivons les potentielles perspectives d’ostéogénèse induite par les corticotomies alvéolaires.
Effect of isoelectronic substitution on phase transition and magnetic properties of Ni57Mn18Ga25−xInx (0 ≤ x ≤ 8) alloys with Ni excess
Authors: Liu Jinghua , Wang Jingmin , Zhang Linfang , Wang Xiao , Hua Hui , Jiang Chengbao
Published: April 2015

Effect of isoelectronic substitution of In for Ga on the phase transition and magnetic properties was studied in Ni57Mn18Ga25−xInx (0 ≤ x ≤ 8) alloys. With the increasing In content, the room-temperature phase structure evolved from tetragonal martensite to cubic austenite. The martensitic transformation temperatures were significantly decreased by the substitution of In for Ga, but the austenitic Curie temperature was only slightly decreased. Especially, both thermal and isothermal magnetization measurements revealed that the Curie temperature and saturation magnetization of the martensite were independent on the isoelectronic substitution. The results were discussed by considering the phase structures and the atomic interactions.
Electrical conduction mechanism in bulk ceramic insulators at high voltages until dielectric breakdown
Authors: Neusel C. , Jelitto H. , Schneider G. A.
Published: April 2015

In order to develop and verify a dielectric breakdown model for bulk insulators thicker than 100 μm, the knowledge of the dominating conduction mechanism at high electric fields, or respectively voltages, is necessary. The dielectric breakdown is the electrical failure of an insulator. In some existing breakdown models, ohmic conduction is assumed as dominating conduction mechanism. For verification, the dominating dc conduction mechanism of bulk insulators at room temperature was investigated by applying high voltages up to 70 kV to the insulator until dielectric breakdown occurs. Four conduction models, namely, ohmic, space charge limited, Schottky, and Poole-Frenkel conduction, were employed to identify the dominating conduction mechanism. Comparing the calculated permittivities from the Schottky and Poole-Frenkel coefficients with experimentally measured permittivity, Schottky and Poole-Frenkel conduction can be excluded as dominating conduction mechanism. Based on the current density voltage characteristics (J-V-curve) and the thickness-dependence of the current density, space charge limited conduction (SCLC) was identified to be the dominating conduction mechanism at high voltages leading to dielectric breakdown. As a consequence, breakdown models based on ohmic conduction are not appropriate to explain the breakdown of the investigated bulk insulators. Furthermore, the electrical failure of the examined bulk insulators can only be described correctly by a breakdown model which includes SCLC as conduction mechanism.
Measurement of single leukemia cell's density and mass using optically induced electric field in a microfluidics chip
Authors: Zhao Yuliang , Lai Hok Sum Sam , Zhang Guanglie , Lee Gwo-Bin , Li Wen Jung
Published: April 2015

We present a method capable of rapidly (∼20 s) determining the density and mass of a single leukemic cell using an optically induced electrokinetics (OEK) platform. Our team had reported recently on a technique that combines sedimentation theory, computer vision, and micro particle manipulation techniques on an OEK microfluidic platform to determine the mass and density of micron-scale entities in a fluidic medium; the mass and density of yeast cells were accurately determined in that prior work. In the work reported in this paper, we further refined the technique by performing significantly more experiments to determine a universal correction factor to Stokes' equation in expressing the drag force on a microparticle as it falls towards an infinite plane. Specifically, a theoretical model for micron-sized spheres settling towards an infinite plane in a microfluidic environment is presented, and which was validated experimentally using five different sizes of micro polystyrene beads. The same sedimentation process was applied to two kinds of leukemic cancer cells with similar sizes in an OEK platform, and their density and mass were determined accordingly. Our tests on mouse lymphocytic leukemia cells (L1210) and human leukemic cells (HL-60) have verified the practical viability of this method. Potentially, this new method provides a new way of measuring the volume, density, and mass of a single cell in an accurate, selective, and repeatable manner.
Solvent-mediated internal conversion in diphenoxyethane-(H2O)nclusters, n = 2-4
Authors: Walsh Patrick S. , Buchanan Evan G. , Gord Joseph R. , Zwier Timothy S.
Published: April 2015

1,2-diphenoxyethane (DPOE) is a flexible bichromophore whose excited states come in close-lying pairs whose splitting and vibronic coupling can be modulated by solvent. Building on the ground state infrared spectroscopy of DPOE-(H2O)n clusters with n = 2-4 from the adjoining paper [Walsh et al., J. Chem. Phys. 142, 154303 (2015)], the present work focuses on the vibronic and excited state infrared spectroscopies of the clusters. The type and degree of asymmetry of the water cluster binding to DPOE is reflected in the variation in the magnitude of the S1/S2 splitting with cluster size. Excited state resonant ion-dip infrared spectroscopy was performed at the electronic origins of the first two excited states in order to explore how the water clusters’ OH stretch spectra report on the nature of the two excited states, and the interaction of the S2 state with nearby S1 vibronic levels mediated by the water clusters. The data set, when taken as a whole, provides a state-to-state view of internal conversion and the role of solvent in mediating conversion of electronic excitation between two chromophores, providing a molecular-scale view of Kasha’s rule.
Distinguishing gramicidin D conformers through two-dimensional infrared spectroscopy of vibrational excitons
Authors: Stevenson Paul , Tokmakoff Andrei
Published: April 2015

Gramicidin D is a short peptide which dimerizes to form helical pores, adopting one of two conformations in the process. These conformations differ primarily in number of residues per turn and the hydrogen-bond registry between rungs of the helix. Using amide I 2D infrared (IR) and FTIR, we have demonstrated that it is possible to distinguish between the different conformers of gramicidin D in solution. We show that the spectra observed for this helical peptide bear no resemblance to the spectra of α- or 310-helices and that while the FTIR spectra appear similar to spectra of β-sheets, 2D IR reveals that the observed resonances arise from vibrational modes unlike those observed in β-sheets. We also present an idealized model which reproduces the experimental data with high fidelity. This model is able to explain the polarization-dependence of the experimental 2D IR data. Using this model, we show the coupling between the rungs of the helix dominates the spectra, and as a consequence of this, the number of residues per turn can greatly influence the amide I spectra of gramicidin D.
Ultrafast vibrational spectroscopy (2D-IR) of CO2 in ionic liquids: Carbon capture from carbon dioxide’s point of view
Authors: Brinzer Thomas , Berquist Eric J. , Ren Zhe , Dutta Samrat , Johnson Clinton A. , Krisher Cullen S. , Lambrecht Daniel S. , Garrett-Roe Sean
Published: April 2015

The CO2ν3 asymmetric stretching mode is established as a vibrational chromophore for ultrafast two-dimensional infrared (2D-IR) spectroscopic studies of local structure and dynamics in ionic liquids, which are of interest for carbon capture applications. CO2 is dissolved in a series of 1-butyl-3-methylimidazolium-based ionic liquids ([C4C1im][X], where [X]− is the anion from the series hexafluorophosphate (PF6−), tetrafluoroborate (BF4−), bis-(trifluoromethyl)sulfonylimide (Tf2N−), triflate (TfO−), trifluoroacetate (TFA−), dicyanamide (DCA−), and thiocyanate (SCN−)). In the ionic liquids studied, the ν3 center frequency is sensitive to the local solvation environment and reports on the timescales for local structural relaxation. Density functional theory calculations predict charge transfer from the anion to the CO2 and from CO2 to the cation. The charge transfer drives geometrical distortion of CO2, which in turn changes the ν3 frequency. The observed structural relaxation timescales vary by up to an order of magnitude between ionic liquids. Shoulders in the 2D-IR spectra arise from anharmonic coupling of the ν2 and ν3 normal modes of CO2. Thermal fluctuations in the ν2 population stochastically modulate the ν3 frequency and generate dynamic cross-peaks. These timescales are attributed to the breakup of ion cages that create a well-defined local environment for CO2. The results suggest that the picosecond dynamics of CO2 are gated by local diffusion of anions and cations.
Enhanced microwave absorption performance of lightweight absorber based on reduced graphene oxide and Ag-coated hollow glass spheres/epoxy composite
Authors: Wang Junpeng , Sun Yu , Chen Wei , Wang Tao , Xu Renxin , Wang Jun
Published: April 2015

Using a combination of Ag-coated hollow glass spheres (HGS@Ag) and a small quantity of graphene sheets within the epoxy matrix, we have prepared a novel lightweight high efficiency microwave absorption composite. Compared with pure HGS@Ag and graphene composite, the −10 dB absorption bandwidth and the minimum reflection loss of the novel composite are improved. Reflection loss exceeding −20 dB is obtained for composites in a wide frequency range and the minimum reflection loss reaches −46 dB while bandwidth less than −10 dB can reach up to 4.1 GHz when an appropriate absorber thickness between 2 and 3.5 mm is chosen. The enhanced microwave absorption performance of the novel composite is due to the enhanced dielectric response, enhanced conductivity, and the trap of electromagnetic radiation with increased propagation paths by multiple reflections.
The study of the structure factor of a wormlike chain in an orientational external field
Authors: Jiang Ying , Zhang Xinghua , Miao Bing , Yan Dadong
Published: April 2015

A precise representation of the structure factor of a wormlike chain for the arbitrary chain flexibility in an orientational external field is obtained by virtue of the numerical solution to the modified diffusion equation satisfied by the Green’s function. The model is built from a standard wormlike chain formalism in a continuous version which crossovers from the rigid-rod limit to the flexible chain limit and the Maier-Saupe interaction which describes the orientational effects from the nematic field. The behaviors of the structure factor in the distinct wavevector k regimes are numerically investigated as functions of chain flexibility and tilt angle between the directors of the nematic field and k. The radius of gyration extracted from the structure factor in small-k regime is also carefully analysed in both the directions along and perpendicular to the nematic axis. Our calculations exactly recover the prediction of the structure factor undergoing an orientational field in the rigid rod limit.
Eddy currents: A misleading contribution when measuring magnetoelectric voltage coefficients of thin film devices
Authors: More-Chevalier J. , Cibert C. , Bouregba R. , Poullain G.
Published: April 2015

Tb0.3Dy0.7Fe2/Pt/PbZr0.56Ti0.44O3 (Terfenol-D/Pt/PZT) magnetoelectric (ME) thin films were deposited on Pt/TiO2/SiO2/Si substrate. The ME voltage coefficient αHME was determined at room temperature using a lock-in amplifier and by applying to the sample an alternating magnetic field of a few mT. Surprisingly, very similar responses were obtained from a simple commercial capacitor set in series with a small loop of wire. This allowed us first to accurately model and reproduce the frequency response of the ferroelectric PZT layer alone. We also observed that, at low frequency, the voltage across the ferroelectric capacitor and the current in the circuit did not decrease significantly when diminishing then removing, the area of the conductive loop. One major conclusion is that eddy currents in the lead wires, rather than the classical electromotive force across conductive loops, contribute significantly to the total voltage response, at least for thin film ME devices. A model taking into account eddy currents was then developed for the extraction of the true αHME. A large αHME of 4.6 V/cm.Oe was thus obtained for the Terfenol-D/Pt/PZT thin film device, without DC magnetic field.
Structural recovery in plastic crystals by time-resolved non-linear dielectric spectroscopy
Authors: Riechers Birte , Samwer Konrad , Richert Ranko
Published: April 2015

The dielectric relaxation of several different plastic crystals has been examined at high amplitudes of the ac electric fields, with the aim of exploring possible differences with respect to supercooled liquids. In all cases, the steady state high field loss spectrum appears to be widened, compared with its low field limit counterpart, whereas peak position and peak amplitude remain almost unchanged. This field induced change in the loss profile is explained on the basis of two distinct effects: an increased relaxation time due to reduced configurational entropy at high fields which affects the low frequency part of the spectrum, and accelerated dynamics at frequencies above the loss peak position resulting from the added energy that the sample absorbs from the external electric field. From the time-resolved assessment of the field induced changes in fictive temperatures at relatively high frequencies, we find that this structural recovery is slaved to the average rather than mode specific structural relaxation time. In other words, the very fast relaxation modes in the plastic crystal cannot adjust their fictive temperatures faster than the slower modes, the equivalent of time aging-time superposition. As a result, an explanation for this single fictive temperature must be consistent with positional order, i.e., translational motion or local density fluctuations do not govern the persistence time of local time constants.
Efficient surface plasmon amplification in gain-assisted silver nanotubes and associated dimers
Authors: Yu HaiQun , Jiang ShuMin , Wu DaJian
Published: April 2015

SPASER (surface plasmon amplification by stimulated emission of radiation) properties in active SiO2–Ag nanotubes and associated dimers have been investigated by using the scattering theory and the finite element method. In the active Ag nanotube, as the gain coefficient of the core increases to a critical value, a super-resonance occurs. The SPASER phenomenon also can be found in the active Ag nanotube dimer. The strong couplings between two nanotubes lead to larger gain threshold for the active Ag nanotube dimer compared with the active Ag nanotube. At the super-resonance, the maximal surface enhanced Raman scattering factor at the “hot spot” in the active Ag nanotube dimer can achieve about 8 × 1018, which is large enough for single molecule detection. Furthermore, with increasing the separation between two Ag nanotubes, the gain threshold value for the super-resonance of the active Ag nanotube dimer decreases, while the corresponding super-resonance wavelength increases first and then decreases.
Three dimensional nonlinear analysis of a single-grating rectangular waveguide Cerenkov maser
Authors: Xie Wenqiu , Wang Zi-Cheng , Luo Jirun , Zhao Ding
Published: April 2015

A three dimensional (3-D) nonlinear model for illustrating the beam-wave interaction in a single-grating rectangular waveguide sheet-beam Cerenkov maser is presented. The dynamical equations and the equations of motion are solved self-consistently to predict the device performance. Space-charge effects and Ohmic losses are considered in the model. A 1.03 THz backward wave oscillator and a 0.65 THz traveling wave tube are discussed as two illustrative examples.
HM+–RG complexes (M = group 2 metal; RG = rare gas): Physical vs. chemical interactions
Authors: Harris Joe P. , Dodson Hannah , Breckenridge W. H. , Wright Timothy G.
Published: April 2015

Previous work on the HM+–He complexes (M = Be–Ra) has been extended to the cases of the heavier rare gas atoms, HM+–RG (RG = Ne–Rn). Optimized geometries and harmonic vibrational frequencies have been calculated using MP2 theory and quadruple-ζ quality basis sets. Dissociation energies for the loss of the rare gas atom have been calculated at these optimized geometries using coupled cluster with single and double excitations and perturbative triples, CCSD(T)theory, extrapolating interaction energies to the basis set limit. Comparisons are made between the present data and the previously obtained helium results, as well as to those of the bare HM+ molecules; furthermore, comparisons are made to the related M+–RG and M2+–RG complexes. Partial atomic charge analyses have also been undertaken, and these used to test a simple charge-induced dipole model. Molecular orbital diagrams are presented together with contour plots of the natural orbitals from the quadratic configuration with single and double excitations (QCISD) density. The conclusion is that the majority of these complexes are physically bound, with very little sharing of electron density; however, for M = Be, and to a lesser extent M = Mg, some evidence for chemical effects is seen in HM+–RG complexes involving RG atoms with the higher atomic numbers.
Non-perturbative aspects of particle acceleration in non-linear electrodynamics
Authors: Burton David A. , Flood Stephen P. , Wen Haibao
Published: April 2015

We undertake an investigation of particle acceleration in the context of non-linear electrodynamics. We deduce the maximum energy that an electron can gain in a non-linear density wave in a magnetised plasma, and we show that an electron can “surf” a sufficiently intense Born-Infeld electromagnetic plane wave and be strongly accelerated by the wave. The first result is valid for a large class of physically reasonable modifications of the linear Maxwell equations, whilst the second result exploits the special mathematical structure of Born-Infeld theory.
An acoustic metamaterial composed of multi-layer membrane-coated perforated plates for low-frequency sound insulation
Authors: Fan Li , Chen Zhe , Zhang Shu-yi , Ding Jin , Li Xiao-juan , Zhang Hui
Published: April 2015

Insulating against low-frequency sound (below 500 Hz) remains challenging despite the progress that has been achieved in sound insulation and absorption. In this work, an acoustic metamaterial based on membrane-coated perforated plates is presented for achieving sound insulation in a low-frequency range, even covering the lower audio frequency limit, 20 Hz. Theoretical analysis and finite element simulations demonstrate that this metamaterial can effectively block acoustic waves over a wide low-frequency band regardless of incident angles. Two mechanisms, non-resonance and monopolar resonance, operate in the metamaterial, resulting in a more powerful sound insulation ability than that achieved using periodically arranged multi-layer solid plates.
High magnetoelectric effect at low magnetic basing in heterostructure rod of magnetostrictive fibers, piezoelectric tube, and epoxy binder
Authors: Leung Chung Ming , Or Siu Wing
Published: April 2015

A three-phase heterostructure rod of 35 mm length and 8 mm diameter is developed by embedding 18 pieces of length-magnetized Tb0.3Dy0.7Fe1.92 magnetostrictive continuous fibers in a wall-thickness-polarized Pb(Zr, Ti)O3 piezoelectric long-thin tube using an epoxy binder in order to study its magnetoelectric (ME) effect for passive sensing of axial magnetic fields. The heterostructure rod exhibits a high non-resonance ME voltage coefficient (αV) of 38 mV/Oe for frequencies up to 10 kHz and an ultrahigh resonance αV of 680 mV/Oe at 32 kHz, both under a reasonably low magnetic bias field (HBias) of 120 Oe. The simultaneously high axial ME responses at the reasonably low HBias, as confirmed theoretically and experimentally, can be ascribed to the realization of the relatively true magnetostrictive 33-mode and piezoelectric 31-mode of operation in the magnetostrictive continuous fibers and piezoelectric long-thin tube, respectively, as well as the reduction in the effect of demagnetization fields in the high aspect-ratio magnetostrictive continuous fibers.
Graphene oxide-Fe3O4 nanoparticle composite with high transverse proton relaxivity value for magnetic resonance imaging
Authors: Venkatesha N. , Poojar Pavan , Qurishi Yasrib , Geethanath Sairam , Srivastava Chandan
Published: April 2015

The potential of graphene oxide–Fe3O4 nanoparticle (GO-Fe3O4) composite as an image contrast enhancing material in magnetic resonance imaging has been investigated. Proton relaxivity values were obtained in three different homogeneous dispersions of GO-Fe3O4 composites synthesized by precipitating Fe3O4 nanoparticles in three different reaction mixtures containing 0.01 g, 0.1 g, and 0.2 g of graphene oxide. A noticeable difference in proton relaxivity values was observed between the three cases. A comprehensive structural and magnetic characterization revealed discrete differences in the extent of reduction of the graphene oxide and spacing between the graphene oxide sheets in the three composites. The GO-Fe3O4 composite framework that contained graphene oxide with least extent of reduction of the carboxyl groups and largest spacing between the graphene oxide sheets provided the optimum structure for yielding a very high transverse proton relaxivity value. It was found that the GO-Fe3O4 composites possessed good biocompatibility with normal cell lines, whereas they exhibited considerable toxicity towards breast cancer cells.
Spectral functions for regular Sturm-Liouville problems
Authors: Fucci Guglielmo , Graham Curtis , Kirsten Klaus
Published: April 2015

In this paper, we provide a detailed analysis of the analytic continuation of the spectral zeta function associated with one-dimensional regular Sturm-Liouville problems endowed with self-adjoint separated and coupled boundary conditions. The spectral zeta function is represented in terms of a complex integral and the analytic continuation in the entire complex plane is achieved by using the well-known Liouville-Green (or WKB) asymptotic expansion of the eigenfunctions associated with the problem. The analytically continued expression of the spectral zeta function is then used to compute the functional determinant of the Sturm-Liouville operator and the coefficients of the asymptotic expansion of the associated heat kernel.
Design and verification of a novel hollow vibrating module for laser machining
Authors: Wang Zhaozhao , Jang Seungbong , Kim EunHee , Jeon Yongho , Lee Soo-Hun , Lee Moon G.
Published: April 2015

If a vibration module is added on laser machining system, the quality of surface finish and aspect ratio on metals can be significantly enhanced. In this study, a single mobility model of vibrating laser along the path of laser beam was put forward. In order to realize the desired unidirectional motion, a resonance type vibration module with optical lens was designed and manufactured. This cylindrical module was composed of curved-beam flexure elements. The cylindrical coordinate system was established to describe the relationship of a curved-beam flexure element’s motion and deformation. In addition, the stiffness matrix of the curved-beam element was obtained. Finite element method and dynamical modeling were provided to analyze the resonance frequency and the displacement of the motion. The feasibility of the design was demonstrated with the help of experiments on frequency response. Experimental results show good agreement with theoretical analysis and simulation predictions.
Anomalous magnetoresistance in magnetized topological insulator cylinders
Authors: Siu Zhuo Bin , Jalil Mansoor B. A.
Published: April 2015

The close coupling between the spin and momentum degrees of freedom in topological insulators (TIs) presents the opportunity for the control of one to manipulate the other. The momentum can, for example, be confined on a curved surface and the spin influenced by applying a magnetic field. In this work, we study the surface states of a cylindrical TI magnetized in the x direction perpendicular to the cylindrical axis lying along the z direction. We show that a large magnetization leads to an upwards bending of the energy bands at small |kz|. The bending leads to an anomalous magnetoresistance where the transmission between two cylinders magnetized in opposite directions is higher than when the cylinders are magnetized at intermediate angles with respect to each other.
A low cost design and fabrication method for developing a leak proof paper based microfluidic device with customized test zone
Authors: Kakoti Ankana , Siddiqui Mohd Farhan , Goswami Pranab
Published: April 2015

This article describes a fabrication process for the generation of a leak proof paper based microfluidic device and a new design strategy for convenient incorporation of externally prepared test zones. Briefly, a negative photolithographic method was used to prepare the device with a partial photoresist layer on the rear of the device to block the leakage of sample. Microscopy and Field Emission Scanning Electron Microscopy data validated the formation of the photoresist layer. The partial layer of photoresist on the device channel limits sample volume to 7 ± 0.2 μl as compared to devices without the partial photoresist layer which requires a larger sample volume of 10 ± 0.1 μl. The design prototype with a customized external test zone exploits the channel protrusions on the UV exposed photoresist treated paper to bridge the externally applied test zone to the sample and absorbent zones. The partially laminated device with an external test zone has a comparatively low wicking speed of 1.8 ± 0.9 mm/min compared to the completely laminated device with an inbuilt test zone (3.3 ± 1.2 mm/min) which extends the reaction time between the analyte and reagents. The efficacy of the prepared device was studied with colorimetric assays for the non-specific detection of protein by tetrabromophenol blue, acid/base with phenolphthalein indicator, and specific detection of proteins using the HRP-DAB chemistry. The prepared device has the potential for leak proof detection of analyte, requires low sample volume, involves reduced cost of production (∼$0.03, excluding reagent and lamination cost), and enables the integration of customized test zones.
Transition from a nanocrystalline phase to an amorphous phase in In-Si-O thin films: The correlation between the microstructure and the optical properties
Authors: Park Jun-Woo , So Hyeon Seob , Lee Hye-Min , Kim Hyo-Joong , Kim Han-Ki , Lee Hosun
Published: April 2015

We investigated the structural and optical properties of In-Si-O thin films as the phase abruptly changes from nanocrystalline (nc) to amorphous (a) with increasing Si content. In-Si-O thin films were deposited on Si substrate using a co-sputtering deposition method. The RF power of the In2O3 target was fixed at 100 W, while the power applied to the SiO2 target was varied between 0 W and 60 W. At the Si = 2.8 at. %, i.e., at the onset of amorphous phase, the optical properties, including the dielectric functions, optical gap energies, and phonon modes, changed abruptly which were triggered by changes in the crystallinity and surface morphology. X-ray diffraction (XRD) spectra showed crystalline (c-) In2O3-like peaks below Si = 2.2%. Additionally, a broad peak associated with an amorphous (a-) In2O3 phase appeared above 2.8%. However, the Raman spectra of In-Si-O showed very weak peaks associated with c-In2O3 below 2.2%, and then showed a strong Raman peak associated with a-In-Si-O above 2.8%. X-ray photoelectron spectroscopy measurements showed that oxygen vacancy-related peak intensities increased abruptly above Si = 2.8%. The contrasting results of XRD and Raman measurements can be explained as follows: first, the large enhancement in Drude tails in the a-In-Si-O phase was caused by Si-induced amorphization and a large increase in the density of oxygen vacancies in the In-Si-O thin films. Second, the apparently drastic increase of the Raman peak intensity near 364 cm−1 (for amorphous phase, i.e., above Si = 2.8%) is attributed to a disorder-activated infrared mode caused by both the amorphization and the increase in the oxygen vacancy density in In-Si-O thin films.
Rayleigh-Taylor vortices in a pair-ion plasma
Authors: Adak Ashish , Khan Manoranjan
Published: April 2015

The Rayleigh-Taylor (RT) vortices and the analytical solution of three-mode coupling in pair-ion plasmas are investigated. It is shown that the E×B convection of polarization drift is responsible for the saturation of growing RT instability and as a result the localized dipole vortex structures are formed. The shear flow generation due to the destruction of vortex structures is discussed by the Fourier mode analysis.