bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential regulation of pancreatic digestive enzymes during chronic high-fat diet-induced obesity in C57BL/6J mice
Authors: Birk Ruth Z. , Rubio-Aliaga Isabel , Boekschoten Mark V. , Danino Hila , Müller Michael , Daniel Hannelore
Published: May 2014

Exocrine pancreatic digestive enzymes are essential for the digestion of dietary components and are regulated by them. Chronic excess dietary high fat (HF) consumption is a contributing factor of diet-induced obesity (DIO) and associated chronic diseases and requires adaptation by the pancreas. The aim of the present study was to investigate the effects of chronic HF diet feeding on exocrine pancreatic digestive enzyme transcript levels in DIO C57BL/6J mice. C57BL/6J mice were fed diets containing either 10 or 45 % energy (E%) derived from fat for 12 weeks (n10 mice per diet group). Pancreatic tissue and blood samples were collected at 0, 4 and 12 weeks. The expression of a panel of exocrine pancreatic digestive enzymes was analysed using quantitative RT-PCR and Western blot analysis. The HF (45 E%) diet-fed C57BL/6J mice developed obesity, hyperleptinaemia, hyperglycaemia and hyperinsulinaemia. The transcript levels of pancreatic lipase (PL), pancreatic lipase-related protein 2 (PLRP2) and pancreatic phospholipase A2 (PLA2) were initially elevated; however, they were down-regulated to basal control levels at week 12. The transcript levels of colipase were significantly affected by diet and time. The protein levels of PL and PLRP2 responded to HF diet feeding. The transcript levels of amylase and proteases were not significantly affected by diet and time. The transcript levels of specific lipases in hyperinsulinaemic, hyperleptinaemic and hyperglycaemic DIO C57BL/6J mice are down-regulated. However, these mice compensate for this by the post-transcriptional regulation of the levels of proteins that respond to dietary fat. This suggests a complex regulatory mechanism involved in the modulation of fat digestion.
A contribution to the familyLecideaceaes. lat. (Lecanoromycetidaeinc. sed., lichenized Ascomycota) in the southern subpolar region; including eight new species and some revised generic circumscriptions
Authors: FRYDAY Alan M. , HERTEL Hannes
Published: May 2014

Eight new species ofLecideaceaeare described from the southern subpolar region:Bryobilimbia coppinsianaFryday, a saxicolous species with one septate ascospores (Campbell Island, New Zealand);Immersaria fuliginosaFryday, with a thallus composed of thalloconidia (Falkland Islands);Lecidea aurantiaFryday, with an orange thallus (Auckland Islands, New Zealand);L. campbellensisFryday, with an endolithic thallus and apothecia resembling those of a species ofPorpidia(Campbell Island);Poeltiaria ochyraeHertel, which is similar toP. subinconguabut with a thick areolate thallus (South Orkney and South Shetland Islands);P. tasmanicaFryday, which is similar toP. urbanskyanabut with smaller ascopores (Tasmania);Poeltidea inspersaFryday with an enolithic thallus and a hymenium with large oil globules (Falkland Islands); andPorpidia vulcanoidesHertel & Fryday with immersed apothecia with a thick margin and large ascospores (SW Chile).Lecidea kalbiiHertel is resurrected from the synonymy ofL. manniiTuck. and treated as a distinct species. The circumscription of genera within theLecideaceaeis also discussed:Poeltiariais shown to be heterogeneous, and the generaLabyrinthaandNotolecideaare reduced to synonymy withPoeltideaandPoeltiariarespectively, and the new combinationsPoeltidia implexa(Malcolmet al.) Hertel & Fryday andPoeltiaria subcontinua(Hertel) Hertel & Fryday made. A key to the genera ofLecideaceaes. lat. is provided.
Structure factorielle d’une version française du Nursing Home Behavior Problem Scale
Authors: Fraser July , Landreville Philippe , Voyer Philippe , Carmichael Pierre-Hugues
Published: May 2014

Several measuring devices are available to assess specific behavioural problems of dementia patients residing in nursing homes but only a few have been translated and validated in French. This study’s main objective was to determine the factorial structure of the French version of the Nursing Home Behavior Problem Scale (NHBPS) with people suffering from dementia. A secondary objective was to document the variables associated with the global score of the NHBPS and the underlying dimensions of the instrument. Participants (n = 155) were diagnosed with dementia and resided in three nursing homes and a hospital’s long-term care unit. The presence of behavioural problems and other characteristics were assessed by two nurses. A factor analysis revealed five key dimensions in the francophone version of the questionnaire. Several variables were associated with the total score of the NHBPS and its five underlying dimensions. Although the factorial solution of the French version of the NHBPS is similar to the English versions, our results also show differences that may depend on methodological characteristics.
Governance of Biomedical Research in Singapore and the Challenge of Conflicts of Interest
Authors: HO CALVIN WAI LOON , DE CASTRO LEONARDO D. , CAMPBELL ALASTAIR V.
Published: May 2014

This article discusses the establishment of a governance framework for biomedical research in Singapore. It focuses on the work of the Bioethics Advisory Committee (BAC), which has been instrumental in institutionalizing a governance framework, through the provision of recommendations to the government, and through the coordination of efforts among government agencies. However, developing capabilities in biomedical sciences presents challenges that are qualitatively different from those of past technologies. The state has a greater role to play in balancing conflicting and potentially irreconcilable economic, social, and political goals. This article analyzes the various ways by which the BAC has facilitated this.
Structural and photophysical study of copper iodide complex with P^N or P^N^P ligand
Authors: Wei Feng , Liu Xiaochen , Liu Zhiwei , Bian Zuqiang , Zhao Yongliang , Huang Chunhui
Published: May 2014

A series of CuI complexes with P^N or P^N^P ligand showing rich structural and photophysical properties were synthesized and studied.
Cobalt(ii), iron(ii), zinc(ii) and palladium(ii) complexes of di-topic 4′-{4-[bis(2-pyridyl)aminomethyl]phenyl}-2,2′:6′,2′′-terpyridine. Synthetic and X-ray structural studies
Authors: Bray David J. , Clegg Jack. K. , Jolliffe Katrina A. , Lindoy Leonard F.
Published: May 2014

A new di-topic hybrid ligand incorporating terpy/dpa domains and the X-ray structures of five of its metal complexes are presented.
Hydrogen-bonding patterns in a series of multi-component molecular solids formed by 2,3,5,6-tetramethylpyrazine with selected carboxylic acids
Authors: Wang Lei , Xue Ruiyu , Li Yuanxin , Zhao Yiran , Liu Faqian , Huang Keke
Published: May 2014

Hydrogen-bonding patterns in a series of cocrystals of 2,3,5,6-tetramethylpyrazine with selected carboxylic acids are discussed.
Functional ingredients from microalgae
Authors: Buono Silvia , Langellotti Antonio Luca , Martello Anna , Rinna Francesca , Fogliano Vincenzo
Published: May 2014

A wide variety of natural sources are under investigation to evaluate their possible use for new functional ingredient formulation.
Versatile post-functionalization of the external shell of cowpea chlorotic mottle virus by using click chemistry
Authors: Hommersom C. A. , Matt B. , van der Ham A. , Cornelissen J. J. L. M. , Katsonis N.
Published: May 2014

We present the modification of the outer protein shell of cowpea chlorotic mottle virus (CCMV) with linear and strained alkyne groups for post-functionalization by click chemistry.
Mimicking the 2-oxoglutaric acid signalling function using molecular probes: insights from structural and functional investigations
Authors: Wang Yang , Liu Xinjun , Laurini Erik , Posocco Paola , Ziarelli Fabio , Fermeglia Maurizio , Qu Fanqi , Pricl Sabrina , Zhang Cheng-Cai , Peng Ling
Published: May 2014

2-Oxoglutaric acid (2-OG) has gained considerable attention because of its newly discovered signalling role in addition to its established metabolic functions.
Synthesis, spectroscopic characterization, pH dependent redox mechanism and DNA binding behavior of chlorohydroxyaniline derivatives
Authors: Shahzad Suniya , Shah Afzal , Sirajuddin Muhammad , Adhikari Bimalendu , Ahmad Khurshid , Rana Usman Ali , Ali Saqib , Khan Gul Shahzada , Qureshi Rumana , Kraatz Heinz-Bernhard
Published: May 2014

Three new chlorohydroxyanilines were synthesized and characterized. The results revealed these compounds to have strong antioxidant activity and DNA binding propensity.
Change‐detection algorithm for short‐circuit fault detection in closed‐loop AC drives
Authors: Meinguet Fabien , Semail Eric , Kestelyn Xavier , Mollet Yves , Gyselinck Johan
Published: May 2014

This study deals with an on‐line method for turn‐to‐turn short‐circuit fault detection in low‐voltage permanent‐magnet synchronous machine drives. Owing to the closed‐loop control, the fault effects are reflected in the voltage. Therefore an appropriate diagnostic index is proposed, which is derived from the positive‐ and negative‐sequences of the voltage references. These sequences are obtained in the time domain via adaptive filters, which require only a few calculations. To increase the sensitivity to the fault, the algorithm is only applied to a part of the voltage references, that is, the output of the proportional–integral controllers. Furthermore, the cumulative‐sum algorithm is introduced to cope with changes of small magnitudes. This algorithm allows a change of a fault index to be detected and can be used as a decision system. The resulting fault detection scheme is computationally cheap and can be embedded in the control unit. Simulations and experimental results validate the proposed method in steady state and the performances under non‐stationary operating conditions are also investigated.
Overview of research evolution in the field of line start permanent magnet synchronous motors
Authors: Ugale Rajaram Tukaram , Chaudhari Bhalchandra Nemichand , Pramanik Ashutosh
Published: May 2014

In this study, wide overview of the existing line start permanent magnet synchronous motors literature is presented. The treatment of the subject has been effectively sub‐divided in to five sections; (i) rotor topologies and design, (ii) steady state analysis, (iii) transient state analysis, (iv) parameter estimation and (v) high efficiency standards. Although, there are numerous papers published in each category, only those important papers which have made significant contributions in the developments and thus triggered research in this field are discussed here.
Decoupled control for integrated rotary–linear switched reluctance motor
Authors: Pan Jianfei , Meng Fanjie , Cao Guangzhong
Published: May 2014

The integrated direct‐drive rotary–linear switched reluctance motor (RLSRM) is investigated in this paper. The characteristics of the RLSRM are further inspected by using the finite element method after theoretical analysis. The torque and force distribution function (TFDF) is proposed for the RLSRM based on the multiphase excitation scheme to decouple the linear and the rotary axis of motion. Based on the simple proportional–integral‐derivative position control algorithm, the experimental results testify the effectiveness of the proposed TFDF for individual control for each axis.
Position fix in terrain referenced navigation using statistical verification
Authors: Yun Se Hyun , Park Chan Gook
Published: May 2014

In this study, a method for retaining the uniqueness of terrain shape and updating using a t‐test is proposed using a batch processing algorithm. Using a correlation algorithm, the batch processing algorithm provides a position fix which is then utilised as input to a Kalman filter to compensate for navigation error in a terrain referenced navigation (TRN) system. However, a positional false fix can occur over flat or repetitive terrain, which then causes the navigation solution to diverge. The aim of this study is to prevent the batch processing algorithm from providing a positional false fix by extending the profile length to allow it to incorporate a uniqueness of terrain. A method for reducing computation time is also proposed using an error covariance of measurement. In addition, the use of a t‐test is proposed to help provide a stable navigation solution. Numerical simulations are performed to evaluate the performance of the proposed method, and the results show that the proposed method performs better than a general batch processing TRN.
Optimal restoration approach to handle multiple actors failure in wireless sensor and actor networks
Authors: Zhao Xinyuan , Wang Neng
Published: May 2014

The connectivity of actor network is vital in the wireless sensor and actor networks because the actors need to perform tasks collaboratively. Relocating actors is an effective solution to restore the connectivity when actors fail. Recent studies proposed relocation solutions which do not optimise the relocation distance. In this study, the authors present a network flow‐based multi‐objects non‐linear mathematical programming model to handle the multiple actors failure. Minimising the total relocation distance and the individual relocation distance are two optimal objects. The model views the actor network as a transportation network and uses the flow balancing condition to reconstruct the connectivity of the network. The simulation results confirm the effectiveness of our model and show that the author's model outperforms other existed approaches in terms of optimal relocation distance in handling multiple failures.
The Rotne-Prager-Yamakawa approximation for periodic systems in a shear flow
Authors: Mizerski Krzysztof A. , Wajnryb Eligiusz , Zuk Pawel J. , Szymczak Piotr
Published: May 2014

Rotne-Prager-Yamakawa approximation is a commonly used approach to model hydrodynamic interactions between particles suspended in fluid. It takes into account all the long-range contributions to the hydrodynamic tensors, with the corrections decaying at least as fast as the inverse fourth power of the interparticle distances, and results in a positive definite mobility matrix, which is fundamental in Brownian dynamics simulations. In this communication, we show how to construct the Rotne-Prager-Yamakawa approximation for the bulk system under shear flow, which is modeled using the Lees-Edwards boundary conditions.
Drifting solutions with elliptic symmetry for the compressible Navier-Stokes equations with density-dependent viscosity
Authors: An Hongli , Yuen Manwai
Published: May 2014

In this paper, we investigate the analytical solutions of the compressible Navier-Stokes equations with dependent-density viscosity. By using the characteristic method, we successfully obtain a class of drifting solutions with elliptic symmetry for the Navier-Stokes model wherein the velocity components are governed by a generalized Emden dynamical system. In particular, when the viscosity variables are taken the same as Yuen [M. W. Yuen, “Analytical solutions to the Navier-Stokes equations,” J. Math. Phys. 49, 113102 (2008)], our solutions constitute a generalization of that obtained by Yuen. Interestingly, numerical simulations show that the analytical solutions can be used to explain the drifting phenomena of the propagation wave like Tsunamis in oceans.
Accurate global potential energy surface for the H + OH+ collision
Authors: Gannouni M. A. , Jaidane N. E. , Halvick P. , Stoecklin T. , Hochlaf M.
Published: May 2014

We mapped the global three-dimensional potential energy surface (3D-PES) of the water cation at the MRCI/aug-cc-pV5Z including the basis set superposition (BSSE) correction. This PES covers the molecular region and the long ranges close to the H + OH+(X3Σ−), the O + H2+(X2Σg+), and the hydrogen exchange channels. The quality of the PES is checked after comparison to previous experimental and theoretical results of the spectroscopic constants of H2O+($\tilde X$X̃2B1) and of the diatomic fragments, the vibronic spectrum, the dissociation energy, and the barrier to linearity for H2O+($\tilde X$X̃2B1). Our data nicely approach those measured and computed previously. The long range parts reproduce quite well the diatomic potentials. In whole, a good agreement is found, which validates our 3D-PES.
A portable time-domain LED fluorimeter for nanosecond fluorescence lifetime measurements
Authors: Wang Hongtao , Qi Ying , Mountziaris T. J. , Salthouse Christopher D.
Published: May 2014

Fluorescence lifetime measurements are becoming increasingly important in chemical and biological research. Time-domain lifetime measurements offer fluorescence multiplexing and improved handling of interferers compared with the frequency-domain technique. In this paper, an all solid-state, filterless, and highly portable light-emitting-diode based time-domain fluorimeter (LED TDF) is reported for the measurement of nanosecond fluorescence lifetimes. LED based excitation provides more wavelengths options compared to laser diode based excitation, but the excitation is less effective due to the uncollimated beam, less optical power, and longer latency in state transition. Pulse triggering and pre-bias techniques were implemented in our LED TDF to improve the peak optical power to over 100 mW. The proposed pulsing circuit achieved an excitation light fall time of less than 2 ns. Electrical resetting technique realized a time-gated photo-detector to remove the interference of the excitation light with fluorescence. These techniques allow the LED fluorimeter to accurately measure the fluorescence lifetime of fluorescein down to concentration of 0.5 μM. In addition, all filters required in traditional instruments are eliminated for the non-attenuated excitation/emission light power. These achievements make the reported device attractive to biochemical laboratories seeking for highly portable lifetime detection devices for developing sensors based on fluorescence lifetime changes. The device was initially validated by measuring the lifetimes of three commercial fluorophores and comparing them with reported lifetime data. It was subsequently used to characterize a ZnSe quantum dot based DNA sensor.
The effect of large amplitude motions on the transition frequency redshift in hydrogen bonded complexes: A physical picture
Authors: Mackeprang Kasper , Kjaergaard Henrik G. , Salmi Teemu , Hänninen Vesa , Halonen Lauri
Published: May 2014

We describe the vibrational transitions of the donor unit in water dimer with an approach that is based on a three-dimensional local mode model. We perform a perturbative treatment of the intermolecular vibrational modes to improve the transition wavenumber of the hydrogen bonded OH-stretching transition. The model accurately predicts the transition wavenumbers of the vibrations in water dimer compared to experimental values and provides a physical picture that explains the redshift of the hydrogen bonded OH-oscillator. We find that it is unnecessary to include all six intermolecular modes in the vibrational model and that their effect can, to a good approximation, be computed using a potential energy surface calculated at a lower level electronic structure method than that used for the unperturbed model.
Hydration and rotational diffusion of levoglucosan in aqueous solutions
Authors: Corezzi S. , Sassi P. , Paolantoni M. , Comez L. , Morresi A. , Fioretto D.
Published: May 2014

Extended frequency range depolarized light scattering measurements of water-levoglucosan solutions are reported at different concentrations and temperatures to assess the effect of the presence and distribution of hydroxyl groups on the dynamics of hydration water. The anhydro bridge, reducing from five to three the number of hydroxyl groups with respect to glucose, considerably affects the hydration properties of levoglucosan with respect to those of mono and disaccharides. In particular, we find that the average retardation of water dynamics is ≈3–4, that is lower than ≈5–6 previously found in glucose, fructose, trehalose, and sucrose. Conversely, the average number of retarded water molecules around levoglucosan is 24, almost double that found in water-glucose mixtures. These results suggest that the ability of sugar molecules to form H-bonds through hydroxyl groups with surrounding water, while producing a more effective retardation, it drastically reduces the spatial extent of the perturbation on the H-bond network. In addition, the analysis of the concentration dependence of the hydration number reveals the aptitude of levoglucosan to produce large aggregates in solution. The analysis of shear viscosity and rotational diffusion time suggests a very short lifetime for these aggregates, typically faster than ≈20 ps.
Computationally efficient algorithms for incorporation of hydrodynamic and excluded volume interactions in Brownian dynamics simulations: A comparative study of the Krylov subspace and Chebyshev based techniques
Authors: Saadat Amir , Khomami Bamin
Published: May 2014

Excluded volume and hydrodynamic interactions play a central role in macromolecular dynamics under equilibrium and non-equilibrium settings. The high computational cost of incorporating the influence of hydrodynamic interaction in meso-scale simulation of polymer dynamics has motivated much research on development of high fidelity and cost efficient techniques. Among them, the Chebyshev polynomial based techniques and the Krylov subspace methods are most promising. To this end, in this study we have developed a series of semi-implicit predictor-corrector Brownian dynamics algorithms for bead-spring chain micromechanical model of polymers that utilizes either the Chebyshev or the Krylov framework. The efficiency and fidelity of these new algorithms in equilibrium (radius of gyration and diffusivity) and non-equilibrium conditions (transient planar extensional flow) are demonstrated with particular emphasis on the new enhancements of the Chebyshev polynomial and the Krylov subspace methods. In turn, the algorithm with the highest efficiency and fidelity, namely, the Krylov subspace method, is used to simulate dilute solutions of high molecular weight polystyrene in uniaxial extensional flow. Finally, it is demonstrated that the bead-spring Brownian dynamics simulation with appropriate inclusion of excluded volume and hydrodynamic interactions can quantitatively predict the observed extensional hardening of polystyrene dilute solutions over a broad molecular weight range.
General theory of multistage geminate reactions of isolated pairs of reactants. I. Kinetic equations
Authors: Doktorov Alexander B. , Kipriyanov Alexey A.
Published: May 2014

General matrix approach to the consideration of multistage geminate reactions of isolated pairs of reactants depending on reactant mobility is formulated on the basis of the concept of “effective” particles. Various elementary reactions (stages of multistage reaction including physicochemical processes of internal quantum state changes) proceeding with the participation of isolated pairs of reactants (or isolated reactants) are taken into account. Investigation has been made in terms of kinetic approach implying the derivation of general (matrix) kinetic equations for local and mean probabilities of finding any of the reaction species in the sample under study (or for local and mean concentrations). The recipes for the calculation of kinetic coefficients of the equations for mean quantities in terms of relative coordinates of reactants have been formulated in the general case of inhomogeneous reacting systems. Important specific case of homogeneous reacting systems is considered.
Photofragmentation spectra of halogenated methanes in the VUV photon energy range
Authors: Cartoni Antonella , Bolognesi Paola , Fainelli Ettore , Avaldi Lorenzo
Published: May 2014

In this paper an investigation of the photofragmentation of dihalomethanes CH2X2 (X = F, Cl, Br, I) and chlorinated methanes (CHnCl4−n with n = 0–3) with VUV helium, neon, and argon discharge lamps is reported and the role played by the different halogen atoms is discussed. Halogenated methanes are a class of molecules used in several fields of chemistry and the study of their physical and chemical proprieties is of fundamental interest. In particular their photodissociation and photoionization are of great importance since the decomposition of these compounds in the atmosphere strongly affects the environment. The results of the present work show that the halogen-loss is the predominant fragmentation channel for these molecules in the VUV photon energy range and confirm their role as reservoir of chlorine, bromine, and iodine atoms in the atmosphere. Moreover, the results highlight the peculiar feature of CH2F2 as a source of both fluorine and hydrogen atoms and the characteristic formation of I2+ and CH2+ ions from the photofragmentation of the CH2I2 molecule.
Pair dynamics and the intermolecular nuclear Overhauser effect (NOE) in liquids analysed by simulation and model theories: Application to an ionic liquid
Authors: Gabl Sonja , Schröder Christian , Braun Daniel , Weingärtner Hermann , Steinhauser Othmar
Published: May 2014

Combining simulation and model theories, this paper analyses the impact of pair dynamics on the intermolecular nuclear Overhauser effect (NOE) in liquids. For the first time, we give a distance resolved NOE. When applied to the ionic liquid 1-ethyl-3-methyl-imidazolium tetrafluoroborate the NOE turns out to be of long-range nature. This behaviour translates to the experimentally measured cross- and longitudinal relaxation rates. We were able to calculate the heteronuclear NOE from simulation data, despite the high computational effort. Model theories are computationally less demanding and cover the complete frequency range of the respective spectral density function, they are usually based on a very simple pair distribution function and the solution of the diffusion equation. In order to model the simulated data sufficiently, these simplifications in structure and dynamics have to be generalised considerably.
Charge transfer effects of ions at the liquid water/vapor interface
Authors: Soniat Marielle , Rick Steven W.
Published: May 2014

Charge transfer (CT), the movement of small amounts of electron density between non-bonded pairs, has been suggested as a driving force for a variety of physical processes. Herein, we examine the effect of CT on ion adsorption to the water liquid-vapor interface. Using a CT force field for molecular dynamics, we construct a potential of mean force (PMF) for Na+, K+, Cl−, and I−. The PMFs were produced with respect to an average interface and an instantaneous interface. An analysis of the PMF relative to the instantaneous surface reveals that the area in which the anions experience a free energy minimum is quite narrow, and the cations feel a steeply repulsive free energy near the interface. CT is seen to have only minor effects on the overall free energy profiles. However, the long-ranged effects of ions are highlighted by the CT model. Due to CT, the water molecules at the surface become charged, even when the ion is over 15 Å away from the surface.
Improving long time behavior of Poisson bracket mapping equation: A non-Hamiltonian approach
Authors: Kim Hyun Woo , Rhee Young Min
Published: May 2014

Understanding nonadiabatic dynamics in complex systems is a challenging subject. A series of semiclassical approaches have been proposed to tackle the problem in various settings. The Poisson bracket mapping equation (PBME) utilizes a partial Wigner transform and a mapping representation for its formulation, and has been developed to describe nonadiabatic processes in an efficient manner. Operationally, it is expressed as a set of Hamilton's equations of motion, similar to more conventional classical molecular dynamics. However, this original Hamiltonian PBME sometimes suffers from a large deviation in accuracy especially in the long time limit. Here, we propose a non-Hamiltonian variant of PBME to improve its behavior especially in that limit. As a benchmark, we simulate spin-boson and photosynthetic model systems and find that it consistently outperforms the original PBME and its Ehrenfest style variant. We explain the source of this improvement by decomposing the components of the mapping Hamiltonian and by assessing the energy flow between the system and the bath. We discuss strengths and weaknesses of our scheme with a viewpoint of offering future prospects.
Electronic nose with a new feature reduction method and a multi-linear classifier for Chinese liquor classification
Authors: Jing Yaqi , Meng Qinghao , Qi Peifeng , Zeng Ming , Li Wei , Ma Shugen
Published: May 2014

An electronic nose (e-nose) was designed to classify Chinese liquors of the same aroma style. A new method of feature reduction which combined feature selection with feature extraction was proposed. Feature selection method used 8 feature-selection algorithms based on information theory and reduced the dimension of the feature space to 41. Kernel entropy component analysis was introduced into the e-nose system as a feature extraction method and the dimension of feature space was reduced to 12. Classification of Chinese liquors was performed by using back propagation artificial neural network (BP-ANN), linear discrimination analysis (LDA), and a multi-linear classifier. The classification rate of the multi-linear classifier was 97.22%, which was higher than LDA and BP-ANN. Finally the classification of Chinese liquors according to their raw materials and geographical origins was performed using the proposed multi-linear classifier and classification rate was 98.75% and 100%, respectively.
Fretting fatigue mechanism of bearing cap bolted joints
Authors: Li Xin , Zuo Zhengxing , Qin Wenjie
Published: May 2014

Fretting fatigue is a common type of failure of the bearing cap bolted joints. This paper proposes a methodology to analyze the fretting fatigue mechanism of the bearing cap bolted joint. A biaxially loading system was designed to simulate fretting fatigue failure under typical engine working condition. Meanwhile, a submodel was developed in the finite element calculation to analyze the contact status and stress distribution of the structural models. The test result shows that long inclined cracks (about 650 μm long, orientation at 17°–34°) initiate at the middle region of the contact interface. As the increase of the bolt pretension load (from 6000 N to 10 000 N), the crack initial location is getting away from the bolt screw, and the fretting fatigue lives is increasing (from 7.8 × 105 to 6.0 × 106). With the fatigue phenomenon and the stress field analysis result, it concludes that the crack initiation is governed by the maximum shear stress; the bolt pretension load and the additional rotate torque caused by the bearing load are the two main factors which affect the fretting fatigue mechanism of the bearing cap bolted joints. It is beneficial to fretting fatigue lives of the bearing cap joints by increasing the bolt pretension load and restraining the oscillation of the bearing cap.
Improved thermoelectric power output from multilayered polyethylenimine doped carbon nanotube based organic composites
Authors: Hewitt Corey A. , Montgomery David S. , Barbalace Ryan L. , Carlson Rowland D. , Carroll David L.
Published: May 2014

By appropriately selecting the carbon nanotube type and n-type dopant for the conduction layers in a multilayered carbon nanotube composite, the total device thermoelectric power output can be increased significantly. The particular materials chosen in this study were raw single walled carbon nanotubes for the p-type layers and polyethylenimine doped single walled carbon nanotubes for the n-type layers. The combination of these two conduction layers leads to a single thermocouple Seebeck coefficient of 96 ± 4 μVK−1, which is 6.3 times higher than that previously reported. This improved Seebeck coefficient leads to a total power output of 14.7 nW per thermocouple at the maximum temperature difference of 50 K, which is 44 times the power output per thermocouple for the previously reported results. Ultimately, these thermoelectric power output improvements help to increase the potential use of these lightweight, flexible, and durable organic multilayered carbon nanotube based thermoelectric modules in low powered electronics applications, where waste heat is available.
How do neighbors affect incipient particle motion in laminar shear flow?
Authors: Agudo J. R. , Dasilva S. , Wierschem A.
Published: May 2014

We experimentally study how neighboring particles affect the incipient motion of particles on regular substrates and exposed to a laminar shear flow. To this end, we determine the critical Shields number and determine whether the particle rolls or slides. The substrates consist of a monolayer of fixed spheres of uniform size that are regularly arranged in triangular and quadratic configurations. Neighboring particles influence the incipient motion by shielding to the shear flow and may inhibit continuous motion once they are in direct contact with the particle. At the low particle Reynolds numbers studied, neighboring spheres on the monolayer only affect the incipient particle motion if they are closer than about 3 particle diameters. Direct contact inhibits continuous motion and results in a strong increase of the critical Shields number. For identical beads, we found two different regimes for the onset of continuous motion. Depending on the substrate geometry, the upstream particle may start to roll like a single particle passing the downstream neighbor or it may push its downstream neighbor forward. In the latter case, the downstream sphere rolls while the upstream bead slides in contact with the downstream neighbor. Both regimes yield about the same critical Shields number although the critical Shields number for single particle motion differs by about 50%. If particle contact is avoided by a sudden jump in the Shields number, the critical Shields number for onset of continuous particle motion can be reduced considerably. Finally, the lowest critical Shields numbers for dislodging buried beads in the configurations studied coincides with the critical Shields number for incipient motion of irregular granular beds.
Contactless automated manipulation of mesoscale objects using opto-fluidic actuation and visual servoing
Authors: Vela Emir , Hafez Moustapha , Régnier Stéphane
Published: May 2014

This work describes an automated opto-fluidic system for parallel non-contact manipulation of microcomponents. The strong dynamics of laser-driven thermocapillary flows were used to drag microcomponents at high speeds. High-speed flows allowed to manipulate micro-objects in a parallel manner only using a single laser and a mirror scanner. An automated process was implemented using visual servoing with a high-speed camera in order to achieve accurately parallel manipulation. Automated manipulation of two glass beads of 30 up to 300 μm in diameter moving in parallel at speeds in the range of mm/s was demonstrated.
Excited-state Raman spectroscopy with and without actinic excitation: S1 Raman spectra of trans-azobenzene
Authors: Dobryakov A. L. , Quick M. , Ioffe I. N. , Granovsky A. A. , Ernsting N. P. , Kovalenko S. A.
Published: May 2014

We show that femtosecond stimulated Raman spectroscopy can record excited-state spectra in the absence of actinic excitation, if the Raman pump is in resonance with an electronic transition. The approach is illustrated by recording S1 and S0 spectra of trans-azobenzene in n-hexane. The S1 spectra were also measured conventionally, upon nπ* (S0 → S1) actinic excitation. The results are discussed and compared to earlier reports.
Ultraviolet laser patterning of porous silicon
Authors: Vega Fidel , Peláez Ramón J. , Kuhn Timo , Afonso Carmen N. , Recio-Sánchez Gonzalo , Martín-Palma Raúl J.
Published: May 2014

This work reports on the fabrication of 1D fringed patterns on nanostructured porous silicon (nanoPS) layers (563, 372, and 290 nm thick). The patterns are fabricated by phase-mask laser interference using single pulses of an UV excimer laser (193 nm, 20 ns pulse duration). The method is a single-step and flexible approach to produce a large variety of patterns formed by alternate regions of almost untransformed nanoPS and regions where its surface has melted and transformed into Si nanoparticles (NPs). The role of laser fluence (5–80 mJ cm−2), and pattern period (6.3–16 μm) on pattern features and surface structuring are discussed. The results show that the diameter of Si NPs increases with fluence up to a saturation value of 75 nm for a fluence ≈40 mJ cm−2. In addition, the percentage of transformed to non-transformed region normalized to the pattern period follows similar fluence dependence regardless the period and thus becomes an excellent control parameter. This dependence is fitted within a thermal model that allows for predicting the in-depth profile of the pattern. The model assumes that transformation occurs whenever the laser-induced temperature increase reaches the melting temperature of nanoPS that has been found to be 0.7 of that of crystalline silicon for a porosity of around 79%. The role of thermal gradients across the pattern is discussed in the light of the experimental results and the calculated temperature profiles, and shows that the contribution of lateral thermal flow to melting is not significant for pattern periods ≥6.3 μm.
Size-dependent hot-phonon dynamics in graphene flakes
Authors: Cunning Benjamin V. , Ishioka Kunie , Brown Christopher L. , Kielpinski Dave
Published: May 2014

We examine the ultrafast carrier phonon dynamics in graphene flakes with different lateral sizes. By using a size-selective centrifugation technique, we create graphene films with graphene flake sizes in the region of 120–450 nm. The transient transmission exhibits two-step relaxation, which are attributed to carrier thermalization followed by hot phonon cooling. We find that the cooling of the hot phonons proceeds faster, by a factor of three, for the smallest graphene flakes.
Non-linear permittivity study of the crossover from ferroelectric to relaxor and cluster glass in BaTi1−xSnxO3 (x = 0.175–0.30)
Authors: Kleemann W. , Miga S. , Xu Z. K. , Lu S. G. , Dec J.
Published: May 2014

The electric susceptibilities χ1, χ2, and χ3 of BaTi1−xSnxO3 ceramics with 0.175 ≤ x ≤ 0.30 are measured at 90 ≤ T ≤ 350 K and 37 ≤ f ≤ 106 Hz. Crossover from ferroelectric (x = 0.175) to relaxor behavior (x = 0.30) via coexistence of both (x = 0.25) is indicated by increasing polydispersivity and suppression of χ2 intensity. The relaxor properties are due to weak random fields acting on dipolar Ti4+ clusters in non-polar Sn4+ environment. Upon cooling frustrated interaction between the blocked polar nanoregions yields a cluster glass ground state for x = 0.30 as verified by the dynamic criticality of χ1, χ3, and the scaled non-linear susceptibility a3.
Electronic density-of-states of amorphous vanadium pentoxide films: Electrochemical data and density functional theory calculations
Authors: Lykissa Iliana , Li Shu-Yi , Ramzan Muhammad , Chakraborty Sudip , Ahuja Rajeev , Granqvist Claes G. , Niklasson Gunnar A.
Published: May 2014

Thin films of V2O5 were prepared by sputter deposition onto transparent and electrically conducting substrates and were found to be X-ray amorphous. Their electrochemical density of states was determined by chronopotentiometry and displayed a pronounced low-energy peak followed by an almost featureless contribution at higher energies. These results were compared with density functional theory calculations for amorphous V2O5. Significant similarities were found between measured data and computations; specifically, the experimental low-energy peak corresponds to a split-off part of the conduction band apparent in the computations. Furthermore, the calculations approximately reproduce the experimental band gap observed in optical measurements.
Dependence of the residual surface resistance of superconducting radio frequency cavities on the cooling dynamics around Tc
Authors: Romanenko A. , Grassellino A. , Melnychuk O. , Sergatskov D. A.
Published: May 2014

We report a strong effect of the cooling dynamics through Tc on the amount of trapped external magnetic flux in superconducting niobium cavities. The effect is similar for fine grain and single crystal niobium and all surface treatments including electropolishing with and without 120 °C baking and nitrogen doping. Direct magnetic field measurements on the cavity walls show that the effect stems from changes in the flux trapping efficiency: slow cooling leads to almost complete flux trapping and higher residual resistance, while fast cooling leads to the much more efficient flux expulsion and lower residual resistance.
Systematic approach of nanoparticle design to enhance the broadband plasmonic scattering effect
Authors: Byun Soohwan , Yong Lee Hak , Yoo Jeonghoon
Published: May 2014

To overcome low conversion efficiency of thin film solar cells, using the localized surface plasmon effect caused by the interaction between the incident beam and metallic nanoparticles inserted in or on the absorbing layer can be a promising alternative to overcome the low efficiency problem. Detail shape and size of nanoparticles are directly related with the localized surface plasmon effect as well as optical properties; however, their detail shape and size are hard to be determined depending only on the theoretical or experimental approach. Therefore, the method focusing on defining structural boundaries would be a useful method for nano or microscale design to generate simple and clear shape. In this study, we adopted the structural optimization scheme based on the phase field method to determine the optimal shape of a silver (Ag) nanoparticle positioned on the upper surface of the absorbing layer. We carried out the design process for broadband wavelength to be taken into account and verified the plasmonic scattering effect enhancement in the absorbing layer by numerical simulations.
An indirectly coupled open-ended resonator applied to characterize dielectric properties of MgTiO3–CaTiO3 powders
Authors: Tuhkala M. , Juuti J. , Jantunen H.
Published: May 2014

The effect of CaTiO3 addition on the complex permittivity of MgTiO3 powder was characterized with an open-ended coaxial cavity resonator in the range of 2.12–3.66 GHz. Permittivities and loss tangents of (1 − x)MgTiO3-xCaTiO3 composite powders with x of 0, 2, 5, and 10 mol. % were measured and compared to theoretical values. Inclusion permittivities and dielectric loss tangents were determined by using Bruggeman symmetric and Looyenga mixing rules and a general mixing model. Additions of CaTiO3 resulted in a clear increase in inclusion permittivities from 13.4 up to 14.9 and in loss tangents from 7.1 × 10−3 up to 8.5 × 10−3. Comparison with the theoretical loss tangent values and quantitative determination of CaTiO3 molar ratios by using measured loss tangents and a general mixing model gave a good correlation. The characterization method was proved to be capable of detecting dielectric changes of MgTiO3–CaTiO3 composite powder and of quantifying the amount of additional substances. This information can be exploited, for example, in the analysis and quality control of different composite powders.
Application of carbon cluster-contained extended plasmas for the high-order harmonic generation of ultrashort pulses
Authors: Ganeev R. A. , Baba M. , Suzuki M. , Kuroda H.
Published: May 2014

We present the studies of the high-order harmonic generation of 802-nm, 64-fs pulses in the extended plasmas contained the carbon-based clusters (fullerenes, nanofibers, nanoparticles, and nanotubes). Our studies show that the 11th–19th harmonics in the 15–33 eV range may originate from the low-sized nanoparticles produced during ablation of large clusters and agglomerates. The conversion efficiency of the 11th harmonic generated from the 5-mm-long fullerene plasma was estimated to be 2 × 10−5.
PMN-PT based quaternary piezoceramics with enhanced piezoelectricity and temperature stability
Authors: Luo Nengneng , Zhang Shujun , Li Qiang , Yan Qingfeng , He Wenhui , Zhang Yiling , Shrout Thomas R
Published: May 2014

The phase structure, piezoelectric, dielectric, and ferroelectric properties of (0.80 − x)PMN-0.10PFN-0.10PZ-xPT were investigated systematically. The morphotropic phase boundary (MPB) was confirmed to be 0.30 < x < 0.34. Both MPB compositions of x = 0.32 and x = 0.33 exhibit high piezoelectric coefficients d33 = 640 pC/N and 580 pC/N, electromechanical couplings kp of 0.53 and 0.52, respectively. Of particular importance is that the composition with x = 0.33 was found to process high field-induced piezoelectric strain coefficient d33* of 680 pm/V, exhibiting a minimal temperature-dependent behavior, being less than 8% in the temperature range of 25–165 °C, which can be further confirmed by d31, with a variation of less than 9%. The temperature-insensitive d33* values can be explained by the counterbalance of the ascending dielectric permittivity and descending polarization with increasing temperature. These features make the PMN-PT based quaternary MPB compositions promising for actuator applications demanding high temperature stability.
Infrared spectroscopy of an epitaxial BaTiO3/SrTiO3 superlattice grown on a (110) SmScO3 substrate
Authors: Železný V. , Soukiassian A. , Schlom D. G. , Xi X. X.
Published: May 2014

Polarized infrared reflectance spectra of a BaTiO3/SrTiO3 superlattice deposited on the (110) cut of SmScO3 substrate and bare substrate have been studied in the broad temperature range from 10 to 650 K. Strong infrared anisotropy of the SmScO3 substrate was observed and explained as a projection of B1u and B2u + B3u phonons into the (110) plane. In the polarization parallel to the c-axis below 200 cm−1, an anomaly in the temperature dependence of the spectra was observed. Fitting the superlattice and substrate spectra, the parameters of optical phonons and their temperature dependence were determined. The superlattice phonon frequencies show only classical behavior, it means frequency hardening on cooling. Anisotropy was also found in the superlattice phonon frequencies and their contributions to static permittivity.
Scaled ZrO2 dielectrics for In0.53Ga0.47As gate stacks with low interface trap densities
Authors: Chobpattana Varistha , Mates Thomas E. , Zhang Jack Y. , Stemmer Susanne
Published: May 2014

ZrO2 dielectrics were grown on n-In0.53Ga0.47As channels by atomic layer deposition, after employing an in-situ cyclic nitrogen plasma/trimethylaluminum surface cleaning procedure. By scaling the ZrO2 thickness, accumulation capacitance densities of 3.5 μF/cm2 at 1 MHz are achieved. The midgap interface trap density is estimated to be in the 1012 cm−2 eV−1 range. Using x-ray photoelectron spectroscopy, it was shown that the interface contained the oxides of In, Ga, and Al, but no As-oxides or As-As bonds within the detection limit. The results allow for insights into the effective passivation of these interfaces.
Anomalous temperature dependence in valence band spectra: A resonant photoemission study of layered perovskite Sr2CoO4
Authors: Pandey Pankaj K. , Choudhary R. J. , Phase D. M.
Published: May 2014

Valence band spectra (VBS) and its modification across Curie temperature (TC) of Sr2CoO4 thin film are studied using resonant photoemission spectroscopy. It is found that VBS mainly consists of hybridized states of Co-3d t2geg and O-2p; however, Co-3d eg states show its prominence only in the ferromagnetic temperature regime. Below TC, spectral weight transfer takes place anomalously from high binding energy (B.E.) region to low B.E. region, signifying the enhanced intermediate or low spin state Co4+ ions. It is suggested that spin-lattice coupling and many-body effects in Sr2CoO4 derived from the strong electron correlations lead to such temperature dependence of VBS.