bluuebunny/crossref_metadata_2025 huggingface dataset:
SCUC‐based optimal power tracing approach for scheduling physical bilateral transactions and its verification via an integrated power‐money flow analysis
Authors: Zhu Songming , Wu Lei , Guan Xiaohong , Wu Jiang
Published: May 2016

This study discusses a security‐constrained unit commitment (SCUC) based optimal power tracing approach, which adopts the proportional power tracing method to trace power flows of the network for simultaneously satisfying physical contract paths and financial contract quantities of bilateral transactions. Thus, optimal solutions of the proposed model, including unit commitment and generation dispatch of generators and angle statuses of phase shifters, would simultaneously meet physical and financial requirements of bilateral transactions, and in turn reduce the impacts of loop flows induced by bilateral transactions to third parties of the networked system. The proposed model is a mixed integer non‐linear programming problem because of the non‐linear proportional power tracing constraints, and the revised outer approximation algorithm is discussed to effectively solve the problem. The effectiveness of the proposed model is further evaluated via an integrated power‐money flow analysis, based on the locational marginal price based energy payments and the min–max fairness policy based transmission usage charges. Numerical case studies show that the proposed model, as compared with traditional financial bilateral transaction models, presents potential advantages to avoid loop flows and reduce the impacts to third parties in terms of energy and transmission usage payments.
Influences of input impedance of oscilloscope on the accuracy of switching overvoltage measuring system
Authors: Sun Qiuqin , Yan Joseph , Wang Feng , Li Qingmin , Chen She
Published: May 2016

The accuracy of switching overvoltage measuring system is significantly affected by the input impedance of oscilloscope. First, the principle of switching overvoltage is presented, followed by a brief introduction to the structure of measuring system. Using the laplace transform, the transfer function of the measuring system is then derived. Its frequency response, ranging from DC to 1 GHz, is investigated in detail. The influences of the input impedance on the amplitude and phase angle responses are clearly revealed. Two typical cases, i.e. unit step response and sinusoidal step response, are also considered in the study. To validate the above analysis, a series of experiments has been performed at a substation. Both the theoretical analysis and the experimental results indicate that the input impedance affects the accuracy of switching overvoltage measuring system significantly. In the case that the impedance is rather small, the voltage waveform displayed on oscilloscope would be considerably distorted from the one stressed on the line. The impedance should be greater than 107 Ω to satisfy the accuracy requirement. On the other hand, it can be also used as a direct indicator to assess the performance of oscilloscope.
Seamless control scheme for distributed energy resources in microgrids
Authors: Karami Marzieh , Seifi Hossein , Mohammadian Mustafa
Published: May 2016

This study presents a method for integrating power sharing and participation in primary frequency response of power system for distributed energy resources in microgrids. This controller is based on power‐angle droop and results in thorough power sharing in islanded mode and constant power in grid connected state. It can be employed in microgrids along with the feature of plug and play for any kind of distributed generation resources involving synchronous generators. Also, this paper analyses the stability of the proposed controller and the conventional power‐angle droops in a microgrid with modelling in state‐space form and linearising around an operating point. It has been shown that the proposed controller results in more stability and accuracy than the conventional controllers. Also, eigenvalues are evaluated to find the best controller parameters for the microgrid stability. Finally, the controller response in different operating conditions of a test microgrid is assessed.
Multilabel statistical shape prior for image segmentation
Authors: Grosgeorge Damien , Petitjean Caroline , Ruan Su
Published: May 2016

Statistical shape models have been widely used to guide the segmentation in an image, thus overcoming noise and occlusions. In this study, the authors present a graph cut‐based segmentation framework, in which multiple objects can be segmented. They design a specific multilabel shape prior, which is integrated into the graph cost function. They also want to enforce spatial constraint between the objects. Towards this aim, they propose a local constraint to forbid the inclusion of an object into another, which is enforced in the regularisation term of the graph energy. They apply the authors’ method to cardiac magnetic resonance images, in which left and right ventricles, and the myocardium are segmented and for which encouraging results are obtained.
Diffusion‐steered super‐resolution method based on the Papoulis–Gerchberg algorithm
Authors: Maiseli Baraka
Published: May 2016

Papoulis‐Gerchberg (PG) algorithm, a technique to extrapolate signals, has attracted many researchers for its lower complexity, higher computational efficiency, and effectiveness. One field that receives these merits is super‐resolution, which fuses multiple band‐limited scenes to generate a high‐resolution image. Most super‐resolution methods based on the PG algorithm, however, underperform when input images are seriously degraded by blur, noise, and sampling. The current study addresses the challenges by embedding the PG algorithm into a super‐resolution minimization problem. The proposed method is iterative and incorporates a diffusion‐driven smoothness prior that updates its regularisation process according to the local image features. This well‐crafted prior, which attempts to overcome the super‐resolution ill‐posedness, provides an automatic interplay between flat and contour regions, and ensures necessary levels of regularisations to generate sharper and detailed images. Results show that the current method outperforms some state‐of‐the‐art super‐resolution approaches including those based on total variation. Even more importantly, the authors' method contains a robust noise suppressor that treats comfortably noisy scenes.
Distance‐adaptive routing and spectrum assignment in rings
Authors: Talebi Sahar , Katib Iyad , Rouskas George N.
Published: May 2016

Distance adaptive spectrum allocation exploits the tradeoff between spectrum width and reach to improve resource utilisation by tailoring the modulation format to the level of impairments along the path. The authors first show that the distance‐adaptive routing and spectrum assignment (DA‐RSA) problem is a special case of a multiprocessor scheduling problem. The authors then develop a suite of efficient and effective DA‐RSA algorithms for ring networks, that build upon list scheduling concepts. This work explores the tradeoffs involved in DA‐RSA algorithm design, and opens up new research directions that may leverage the vast literature in scheduling theory.
Control and mitigation of current harmonics in inverter‐fed permanent magnet synchronous machines with non‐linear magnetics
Authors: Richter Jan , Doppelbauer Martin
Published: May 2016

Inverter non‐linearities and machine spatial harmonics yield voltage errors that make harmonic current control and mitigation a challenging task. In this study, a method is presented that allows online identification and compensation of these effects to enable precise control and mitigation of current harmonics of interior permanent magnet synchronous machines with non‐linear magnetics. The method requires no additional sensors and only fundamental machine model parameters. It can be implemented easily in the control software of existing inverter systems. Test bench measurements show excellent current harmonic mitigation capability, good dynamic performance and precise control of arbitrary current harmonics. The principle is transferable to other machine types and grid applications enabling the control and mitigation of current harmonics in a wide field of applications.
Evaluation of anti‐islanding techniques for renewable energy powered distributed generators using analytic network process
Authors: Datta Asim , Saha Debasree , Ray Amitava , Das Priyanath
Published: May 2016

Recent high penetration of renewable energy powered distributed generation (RE‐DG) is imposing new challenges to the anti‐islanding protection. A survey on the existing islanding‐detection techniques (IDTs) reveals that a wide variety of IDTs are available. Thus, it is an anxiety to decide which kind of islanding‐detection method is suitable for a particular RE‐DG application. Therefore, it is of great significance to select an appropriate IDT depending on the application and criteria preference of the end‐users. There can be mutual correlation among the different criteria of anti‐islanding selection. In this research, a decision‐making technique, the analytic network process, is adopted to select an appropriate IDT for a particular RE‐DG application by analysing operational characteristics of different IDTs. Unlike hierarchy‐based approach, the technique considers the interrelationships amongst the attributes of anti‐islanding selection in order to provide the best selection. Finally, the sensitivity analysis is performed to check the robustness of the selection procedure.
AGC of dish‐Stirling solar thermal integrated thermal system with biogeography based optimised three degree of freedom PID controller
Authors: Rahman Asadur , Saikia Lalit C. , Sinha Nidul
Published: May 2016

The present study emphasises the application of dish‐Stirling solar thermal system (DSTS) in automatic generation control (AGC) of an unequal two area thermal system. The thermal systems are equipped with single reheat turbine, generation rate constraint, and governor dead band. The system dynamics with and without DSTS are tested for integral, proportional integral, proportional integral derivative, and three degree of freedom proportional integral derivative (3DOF‐PID) as secondary controllers. The simultaneous optimisation of the controller parameters for each controller is done with biogeography based optimisation (BBO) technique. The 3DOF‐PID controllers for the system having DSTS outperform the other controllers in terms of magnitude of oscillation, peak deviation, and settling time in system dynamic responses. The same is validated with random load perturbation. Sensitivity analysis proves that BBO optimised 3DOF‐PID controller parameters obtained at nominal conditions are healthy enough. These optimised 3DOF‐PID controller parameters are not necessarily needed to optimise for wide changes in system loading, and inertia constant H; step load perturbation (SLP) in all areas and higher SLP in area1. Integration of DSTS for AGC of thermal system is safely attributed.
Dynamic analysis and modelling of a Francis hydro‐energy generation system in the load rejection transient
Authors: Li Huanhuan , Chen Diyi , Zhang Xinguang , Wu Yonghong
Published: May 2016

In this study, the authors propose a novel non‐linear mathematical model of a hydro‐energy generation system in the load rejection transient considering the elastic water hammer‐impact of the penstock and the non‐linear characteristics of the generator. More specifically, six dynamic transfer coefficients of the hydro‐turbine are introduced to the generation system. Furthermore, the dynamic behaviours of the system are investigated using bifurcation diagrams and time waveforms from the point of engineering. Finally, these methods and analytical results will supply some principles for designing and running a hydropower station.
Enhancement of transient stability of distribution system with SCIG and DFIG based wind farms using STATCOM
Authors: Kailasa Gounder Yasoda , Nanjundappan Devarajan , Boominathan Veerakumar
Published: May 2016

This study proposes optimal rating and location of static synchronous compensator (STATCOM) for enhancing transient voltage stability of a real distribution network with wind power generation. The test network consists of fixed and variable speed wind turbines connected to a rural load centre. To ensure reliable and secure operation of the grid, the wind farm (WF) has to comply with the grid code for its low‐voltage ride through operation. Loads play significant role in voltage stability analysis. Induction motors and general loads are modelled according to real‐time data available with the system operator. In this study, dynamic reactive power requirement of WFs is considered for determination of rating of the STATCOM. Reactive power margin (Qmargin) of load bus is used as an index to identify the location of the STATCOM. Extensive simulation has been carried out in DIgSILENT to show the validity of the proposed approach.
Influence of colloidal silica dispersion on the decrease of roughness in silicon chemical mechanical polishing
Authors: Chen Gaopan , Luo Guihai , Pan Guoshun , Liu Yuhong , Luo Haimen
Published: May 2016

Colloidal silica with different dispersion states during silicon chemical mechanical polishing (CMP) are investigated in detail. As the dispersion of colloidal silica is improved, the roughness (Ra) decreases gradually during polishing. The silicon surface has a minimum Ra of 0.118 nm when the polydispersity index of particles is 0.078. Comparing with surface polished by colloidal silica in poor dispersion, the surface quality has great improvement. The important role of dispersant is presented by the results of investigations. The research results indicate that dispersant makes aggregate micelles dispersed into many smaller uniform colloidal silica particles. The uniformly dispersed colloidal silica forms a thin film between the surfaces of silicon and polishing pad during CMP, which is beneficial for the stability of friction, and therefore greatly decreases roughness of silicon surface after polishing.
Fabrication of silver/beta‐tricalcium phosphate particle by a simple liquid chemical reduction method
Authors: Guo Chao , Xue Juan , Tan Ying , Dong Yinsheng
Published: May 2016

Using beta‐tricalcium phosphate (beta‐TCP), silver nitrate and glucose as the carrier, silver resource and reducing agent, silver/beta‐TCP particle was successfully fabricated by a novel liquid chemical reduction method to overcome the infection problem of beta‐TCP. The X‐ray diffraction pattern of the as‐obtained sample confirmed the existence of metallic silver in the particle. The addition of silver nanoparticle affected the thermal stability of beta‐TCP and prevented the transformation from beta‐TCP to alpha‐TCP. Transmission electron microscopy images and the corresponding calculation result proved the mean size and size distribution of silver nanoparticles in the silver/beta‐TCP particle could be controlled by varying the molar ratio between beta‐TCP and silver nitrate. Moreover, the mean size and size distribution of silver nanoparticles also could be changed by using different stabilisers. The prepared silver/beta‐TCP particle is a potential biomaterial to replace pure beta‐TCP particle and utilise for coating material and other applications.
Outcomes of Late Implantation in Usher Syndrome Patients
Authors: Hoshino Ana , Echegoyen Agustina , Goffi-Gomez Maria , Tsuji Robinson , Bento Ricardo
Published: May 2016

Introduction Usher syndrome (US) is an autosomal recessive disorder characterized by hearing loss and progressive visual impairment. Some deaf Usher syndrome patients learn to communicate using sign language. During adolescence, as they start losing vision, they are usually referred to cochlear implantation as a salvage for their new condition. Is a late implantation beneficial to these children?

Objective The objective of this study is to describe the outcomes of US patients who received cochlear implants at a later age.

Methods This is a retrospective study of ten patients diagnosed with US1. We collected pure-tone thresholds and speech perception tests from pre and one-year post implant.

Results Average age at implantation was 18.9 years (5–49). Aided average thresholds were 103 dB HL and 35 dB HL pre and one-year post implant, respectively. Speech perception was only possible to be measured in four patients preoperatively, who scored 13.3; 26.67; 46% vowels and 56% 4-choice. All patients except one had some kind of communication. Two were bilingual. After one year of using the device, seven patients were able to perform the speech tests (from four-choice to close set sentences) and three patients abandoned the use of the implant.

Conclusion We observed that detection of sounds can be achieved with late implantation, but speech recognition is only possible in patients with previous hearing stimulation, since it depends on the development of hearing skills and the maturation of the auditory pathways.
Stolpersteine bei der Interpretation des populationsattributablen Risikos
Authors: Kowall B. , Stang A.
Published: May 2016

Populationsattributable Risiken (PARs) werden in den Gesundheitswissenschaften häufig herangezogen, weil sie eine scheinbar einfache Antwort auf die Frage geben, welcher Anteil der Fälle einer Erkrankung in einer Population vermieden werden könnte, wenn ein oder mehrere Risikofaktoren für diese Erkrankung eliminiert würden. Im vorliegenden Beitrag werden einige Probleme von PARs erläutert, die sich daraus ergeben, dass Krankheiten durch mehrere Ursachen hervorgerufen werden. Darüber hinaus werden Voraussetzungen diskutiert, die erfüllt sein müssen, damit für Präventionsmaßnahmen berechnete Werte von PARs eine realistische Aussage darüber erlauben, um welchen Anteil eine Krankheitslast reduziert werden kann.
Basal entrainment by Newtonian gravity-driven flows
Authors: Bates Belinda M. , Andreini Nicolas , Ancey Christophe
Published: May 2016

Gravity-driven flows can erode the bed along which they descend and increase their mass by a factor of 10 or more. This process is called “basal entrainment.” Although documented by field observations and laboratory experiments, it remains poorly understood. This paper examines what happens when a viscous gravity-driven flow generated by releasing a fixed volume of incompressible Newtonian fluid encounters a stationary layer (composed of fluid with the same density and viscosity). Models based on depth-averaged mass and momentum balance equations deal with bed-flow interfaces as shock waves. In contrast, we use an approach involving the long-wave approximation of the Navier-Stokes equations (lubrication theory), and in this context, bed-flow interfaces are acceleration waves that move quickly across thin stationary layers. The incoming flow digs down into the bed, pushing up downstream material, thus advancing the flow front. Extending the method used by Huppert [“The propagation of two-dimensional and axisymmetric viscous gravity currents over a rigid horizontal surface,” J. Fluid Mech. 121, 43–58 (1982)] for modeling viscous dam-break waves, we end up with a nonlinear diffusion equation for the flow depth, which is solved numerically. Theory is compared with experimental results. Excellent agreement is found in the limit of low Reynolds numbers (i.e., for flow Reynolds numbers lower than 20) for the front position over time and flow depth profile.
Accelerating molecular property calculations with nonorthonormal Krylov space methods
Authors: Furche Filipp , Krull Brandon T. , Nguyen Brian D. , Kwon Jake
Published: May 2016

We formulate Krylov space methods for large eigenvalue problems and linear equation systems that take advantage of decreasing residual norms to reduce the cost of matrix-vector multiplication. The residuals are used as subspace basis without prior orthonormalization, which leads to generalized eigenvalue problems or linear equation systems on the Krylov space. These nonorthonormal Krylov space (nKs) algorithms are favorable for large matrices with irregular sparsity patterns whose elements are computed on the fly, because fewer operations are necessary as the residual norm decreases as compared to the conventional method, while errors in the desired eigenpairs and solution vectors remain small. We consider real symmetric and symplectic eigenvalue problems as well as linear equation systems and Sylvester equations as they appear in configuration interaction and response theory. The nKs method can be implemented in existing electronic structure codes with minor modifications and yields speed-ups of 1.2-1.8 in typical time-dependent Hartree-Fock and density functional applications without accuracy loss. The algorithm can compute entire linear subspaces simultaneously which benefits electronic spectra and force constant calculations requiring many eigenpairs or solution vectors. The nKs approach is related to difference density methods in electronic ground state calculations and particularly efficient for integral direct computations of exchange-type contractions. By combination with resolution-of-the-identity methods for Coulomb contractions, three- to fivefold speed-ups of hybrid time-dependent density functional excited state and response calculations are achieved.
Tuning the charge states of CrW2O9 clusters deposited on perfect and defective MgO(001) surfaces with different color centers: A comprehensive DFT study
Authors: Zhu Jia , Zhang Hui , Tong Yawen , Wang Chengxing , Wang Bin , Huang Xin , Zhang Yongfan
Published: May 2016

The structures and electronic properties of bimetallic oxide CrW2O9 clusters supported on the perfect and defective MgO(001) surfaces with three different color centers, FS0, FS+, and FS2+ centers, respectively, have been investigated by density functional theory calculations. Our results show that the configurations, adsorption energies, charge transfers, and bonding modes of dispersed CrW2O9 clusters are sensitive to the charge states of the FS centers. Compared with the gas-phase configuration, the CrW2O9 clusters supported on the defective surfaces are distorted dramatically, which exhibit different chain structures. On the perfect MgO surface, the depositions of clusters do not involve obvious charge transfer, while the situation is quite different on the defective MgO(001) surfaces in which significant electron transfer occurs from the surface to the cluster. Interestingly, this effect becomes more remarkable for electron-rich oxygen vacancies (FS0 center) than that for electron-poor oxygen vacancies (FS+ and FS2+ centers). Furthermore, our work reveals a progressive Brønsted acid sites where spin density preferentially localized around the Cr atoms not the W atoms for all kinds of FS-centers, indicating the better catalytic activities can be expected for CrW2O9 cluster on defective MgO(001) surfaces with respect to the W3O9 cluster.
Optimal space of linear classical observables for Maxwell k-forms via spacelike and timelike compact de Rham cohomologies
Authors: Benini Marco
Published: May 2016

Being motivated by open questions in gauge field theories, we consider non-standard de Rham cohomology groups for timelike compact and spacelike compact support systems. These cohomology groups are shown to be isomorphic respectively to the usual de Rham cohomology of a spacelike Cauchy surface and its counterpart with compact support. Furthermore, an analog of the usual Poincaré duality for de Rham cohomology is shown to hold for the case with non-standard supports as well. We apply these results to find optimal spaces of linear observables for analogs of arbitrary degree k of both the vector potential and the Faraday tensor. The term optimal has to be intended in the following sense: The spaces of linear observables we consider distinguish between different configurations; in addition to that, there are no redundant observables. This last point in particular heavily relies on the analog of Poincaré duality for the new cohomology groups.
Doping mechanism in pure CuInSe2
Authors: Werner F. , Colombara D. , Melchiorre M. , Valle N. , El Adib B. , Spindler C. , Siebentritt S.
Published: May 2016

We investigate the dopant concentration and majority carrier mobility in epitaxial CuInSe2 thin films for different copper-to-indium ratios and selenium excess during growth. We find that all copper-poor samples are n-type, and that hopping conduction in a shallow donor state plays a significant role for carrier transport. Annealing in sodium ambient enhances gallium in-diffusion from the substrate wafer and changes the net doping of the previously n-type samples to p-type. We suggest that sodium incorporation from the glass might be responsible for the observed p-type doping in polycrystalline Cu-poor CuInSe2 solar cell absorbers.
Near-field acousto monitoring shear interactions inside a drop of fluid: The role of the zero-slip condition
Authors: Wang Xiaohua , Fernandez Rodolfo , Li Nan , Hung Hsien-Chih , Venkataraman Anuradha , Nordstrom Richard , La Rosa Andres H.
Published: May 2016

A full understanding of nanometer-range (near-field) interactions between two sliding solid boundaries, with a mesoscopic fluid layer sandwiched in between, remains challenging. In particular, the origin of the blue-shift resonance frequency experienced by a laterally oscillating probe when approaching a substrate is still a matter of controversy. A simpler problem is addressed here, where a laterally oscillating solid probe interacts with a more sizable drop of fluid that rests on a substrate, aiming at identifying interaction mechanisms that could also be present in the near-field interaction case. It is found that the inelastic component of the probe-fluid interaction does not constitute the main energy-dissipation channel and has a weak dependence on fluid’s viscosity, which is attributed to the zero-slip hydrodynamic condition. In contrast, the acoustic signal engendered by the fluid has a stronger dependence on the fluid’s viscosity (attributed also to the zero-slip hydrodynamic condition) and correlates well with the probe’s resonance frequency red-shift. We propose a similar mechanism happens in near field experiments, but a blue-shift in the probe’s resonance results as a consequence of the fluid molecules (subjected to the zero-slip condition at both the probe and substrate boundaries) exerting instead a spring type restoring force on the probe.
Thermal Marangoni instability of a thin film flowing down a thick wall deformed in the backside
Authors: Dávalos-Orozco L. A.
Published: May 2016

The nonlinear instability of a thin liquid film flowing down a heated thick wall with deformations in the backside is investigated. Here it is assumed that the wall deformations are sinusoidal in space. Time dependent perturbations are imposed at the origin of the free surface of the film. It is found that the wall deformations have an important influence on the flow instability. Moreover, it is shown that the free surface has a large amplitude spatial response to the backside deformations of the wall. This response increases its amplitude considerably when decreasing the wall spatial wavelength down to the wavelength of the time dependent perturbations. At that point, numerical analysis reveals that the time dependent perturbations in some cases are almost impossible to observe on the free surface response. However, in other cases, their interaction produces large amplitude nonlinear wave modulations.
Laser-driven electron acceleration in a plasma channel with an additional electric field
Authors: Cheng Li-Hong , Xue Ju-Kui , Liu Jie
Published: May 2016

We examine the electron acceleration in a two-dimensional plasma channel under the action of a laser field and an additional static electric field. We propose to design an appropriate additional electric field (its direction and location), in order to launch the electron onto an energetic trajectory. We find that the electron acceleration strongly depends on the coupled effects of the laser polarization, the direction, and location of the additional electric field. The additional electric field affects the electron dynamics by changing the dephasing rate. Particularly, a suitably designed additional electric field leads to a considerable energy gain from the laser pulse after the interaction with the additional electric field. The electron energy gain from the laser with the additional electric field can be much higher than that without the additional electric field. This engineering provides a possible means for producing high energetic electrons.
All-optical beam deflection method for simultaneous thermal conductivity and thermo-optic coefficient (dn/dT) measurements
Authors: Putnam Shawn A. , Fairchild Steven B. , Arends Armando A. , Urbas Augustine M.
Published: May 2016

This work describes an all-optical beam deflection method to simultaneously measure the thermal conductivity (Λ) and thermo-optic coefficient (dn/dT) of materials that are absorbing at λ= 10.6 μm and are transparent to semi-transparent at λ= 632.8 nm. The technique is based on the principle of measuring the beam deflection of a probe beam (632.8 nm) in the frequency-domain due to a spatially and temporally varying index gradient that is thermally induced by 50:50 split pump beam from a CO2 laser (10.6 μm). The technique and analysis methods are validated with measurements of 10 different optical materials having Λ and dn/dT properties ranging between 0.7 W/m K ≲Λ≲ 33.5 W/m K and −12 × 10−6 K−1 ≲dn/dT≲ 14 × 10−6 K−1, respectively. The described beam deflection technique is highly related to other well-established, all-optical materials characterization methods, namely, thermal lensing and photothermal deflection spectroscopy. Likewise, due to its all-optical, pump-probe nature, it is applicable to materials characterization in extreme environments with minimal errors due to black-body radiation. In addition, the measurement principle can be extended over a broad range of electromagnetic wavelengths (e.g., ultraviolet to THz) provided the required sources, detectors, and focusing elements are available.
Self-localized and self-constricted electromagnetic field in plasma and atmosphere
Authors: Alanakyan Yu. R.
Published: May 2016

A possibility of creation of a super-high-frequency electromagnetic-field clot in the plasma is shown. Two cases of the field self-localization in the plasma are considered. In the first case, a super-high-frequency electric field creates an annular channel by displacing the plasma and induces a curl-like magnetic field inside. In the second case, the electric field creates a toroidal channel where different field structures are possible. For example, the magnetic lines of the force are aligned along the big circle of the torus, while the curl-like electric lines are aligned along the small circle. Otherwise, the magnetic field is curl-like and the electric-field lines are aligned along the big circle. We evaluate the electric field energy that is required for a curl-like structure of about 3 cm in size to exist during 10 s in the atmospheric air. This energy sustains plasma in the vicinity of the curl-like area.
Damping of electron center-of-mass oscillation in ultracold plasmas
Authors: Chen Wei-Ting , Witte Craig , Roberts Jacob L.
Published: May 2016

Applying a short electric field pulse to an ultracold plasma induces an electron plasma oscillation. This manifests itself as an oscillation of the electron center of mass around the ion center of mass in the ultracold plasma. In general, the oscillation can damp due to either collisionless or collisional mechanisms, or a combination of the both. To investigate the nature of oscillation damping in ultracold plasmas, we developed a molecular dynamics model of the ultracold plasma electrons. Through this model, we found that depending on the neutrality of the ultracold plasma and the size of an applied DC electric field, there are some parameter ranges where the damping is primarily collisional and some primarily collisionless. We conducted experiments to compare the measured damping rate with theory predictions and found them to be in good agreement. Extension of our measurements to different parameter ranges should enable studies for strong-coupling influence on electron-ion collision rates.
Surfactant-assisted growth and properties of rare-earth arsenide InGaAs nanocomposites for terahertz generation
Authors: Salas R. , Guchhait S. , McNicholas K. M. , Sifferman S. D. , Dasika V. D. , Jung D. , Krivoy E. M. , Lee M. L. , Bank S. R.
Published: May 2016

We explore the effects of surfactant-mediated epitaxy on the structural, electrical, and optical properties of fast metal-semiconductor superlattice photoconductors. Specifically, application of a bismuth flux during growth was found to significantly improve the properties of superlattices of LuAs nanoparticles embedded in In0.53Ga0.47As. These improvements are attributed to the enhanced structural quality of the overgrown InGaAs over the LuAs nanoparticles. The use of bismuth enabled a 30% increase in the number of monolayers of LuAs that could be deposited before the InGaAs overgrowth degraded. Dark resistivity increased by up to ∼15× while carrier mobility remained over 2300 cm2/V-s and carrier lifetimes were reduced by >2× at comparable levels of LuAs deposition. These findings demonstrate that surfactant-mediated epitaxy is a promising approach to enhance the properties of ultrafast photoconductors for terahert generation.
Active laser ranging with frequency transfer using frequency comb
Authors: Zhang Hongyuan , Wei Haoyun , Yang Honglei , Li Yan
Published: May 2016

A comb-based active laser ranging scheme is proposed for enhanced distance resolution and a common time standard for the entire system. Three frequency combs with different repetition rates are used as light sources at the two ends where the distance is measured. Pulse positions are determined through asynchronous optical sampling and type II second harmonic generation. Results show that the system achieves a maximum residual of 379.6 nm and a standard deviation of 92.9 nm with 2000 averages over 23.6 m. Moreover, as for the frequency transfer, an atom clock and an adjustable signal generator, synchronized to the atom clock, are used as time standards for the two ends to appraise the frequency deviation introduced by the proposed system. The system achieves a residual fractional deviation of 1.3 × 10−16 for 1 s, allowing precise frequency transfer between the two clocks at the two ends.
Prediction of variation in d-orbital occupancy in strain induced tetragonal phase of BiFeO3 thin film
Authors: Verma Manish , Ram Kanik
Published: May 2016

A theoretical study of the possible variation of d-orbital occupancy while going from the rhombohedral bulk phase to the strain induced tetragonal phase of BiFeO3 thin film has been carried out. A possible existence of an intermediate spin (IS) state, S=3/2 and a low spin (LS) state, S=1/2 in the tetragonal phase has been predicted, thereby clearly establishing the role of strain behind the d-orbital occupancy.
BH-DFTB/DFT calculations for iron clusters
Authors: Aktürk Abdurrahman , Sebetci Ali
Published: May 2016

We present a study on the structural, electronic, and magnetic properties of Fen(n  =  2  −  20) clusters by performing density functional tight binding (DFTB) calculations within a basin hopping (BH) global optimization search followed by density functional theory (DFT) investigations. The structures, total energies and total spin magnetic moments are calculated and compared with previously reported theoretical and experimental results. Two basis sets SDD with ECP and 6-31G** are employed in the DFT calculations together with BLYP GGA exchange-correlation functional. The results indicate that the offered BH-DFTB/DFT strategy collects all the global minima of which different minima have been reported in the previous studies by different groups. Small Fe clusters have three kinds of packing; icosahedral (Fe9−13), centered hexagonal antiprism (Fe14−17, Fe20), and truncated decahedral (Fe17(2), Fe18−19). It is obtained in a qualitative agreement with the time of flight mass spectra that the magic numbers for the small Fe clusters are 7, 13, 15, and 19 and with the collision induced dissociation experiments that the sizes 6, 7, 13, 15, and 19 are thermodynamically more stable than their neighboring sizes. The spin magnetic moment per atom of Fen(n = 2 − 20) clusters is between 2.4 and 3.6 μB for the most of the sizes. The antiferromagnetic coupling between the central and the surface atoms of the Fe13 icosahedron, which have already been reported by experimental and theoretical studies, is verified by our calculations as well. The quantitative disagreements between the calculations and measurements of the magnetic moments of the individual sizes are still to be resolved.
Crude glycerin as a replacement for corn in starter feed: performance and metabolism of pre-weaned dairy calves
Authors: Bittar C. M. M. , Nápoles G. G. O. , Oltramari C. E. , Silva J. T. , De Paula M. R. , Santos F. H. R. , Gallo M. P. C. , Mourão G. B.
Published: May 2016

The purpose of this study was to evaluate the effect of partial replacement of corn in the starter feed with crude glycerin on performance and energy metabolism of liquid-fed dairy calves. Twenty-four newborn individually housed Holstein calves were blocked according to weight and date of birth and randomly assigned to different starter feed treatments during 8 weeks: no crude glycerin; 5% crude glycerin; 10% crude glycerin on dry matter basis. All calves were individually fed daily 4 L of a commercial milk replacer (22.3% crude protein and 19.3% fat). Calves had individual access to starter diet and ad libitum access to water daily. Individual feed intake and faecal scores were recorded daily. Bodyweight and corporal measurements (heart girth, hip width, and withers height) were weekly recorded. From the second week of age, blood samples were collected weekly, 2 h after morning feeding, for determination of plasma glucose and β-hydroxybutyrate concentrations. Ruminal fluid was collected at 4, 6 and 8 weeks of age for determination of pH and short-chain fatty acids. At the end of the eighth week, animals were harvested to evaluate development of the proximal digestive tract. Feed intake, average daily gain, bodyweight or body measurements were not affected (P > 0.05) by the inclusion of crude glycerin in the starter feed. Faecal scores indicated that most of the calves had mild diarrhoea, with no treatment effect. Total short-chain fatty acids and the concentration of individual acids, as well as blood parameters, were not affected (P > 0.05) by the feed treatments. The total forestomach weight, the average weight of each compartment, the maximum capacity of reticulum-rumen, and papillae number, height and width were not affected (P > 0.05). In conclusion, crude glycerin can be used as an alternative energy source, replacing corn up to 10% in the starter feed for liquid-fed dairy calves without affecting growth, rumen development or metabolism.
Effects of oats grain supplements on performance, rumen parameters and composition of beef from cattle grazing oats pasture
Authors: Arelovich H. M. , Marinissen J. , Gardner B. A. , Martínez M. F. , Bravo R. D.
Published: May 2016

The impacts of supplementing with whole oats grain (OG) upon performance and beef quality traits of growing steers grazing oats pasture (OP) were measured. The trial used Angus steer calves (203 kg mean bodyweight) assigned to three treatments: Control, unsupplemented OP (CON); OP plus OG fed at 0.25% BW daily (OG1); and OP plus OG fed at 0.50% bodyweight daily (OG2). All steers grazed the same paddock but were removed momentarily once daily so OG could be fed to each steer individually. Daily intake of OG averaged 597 and 1294 g DM for OG1 and OG2, respectively. Steers were slaughtered after grazing for 130 days to determine carcass characteristics and lipid profiles. In parallel with the grazing trial, four ruminally cannulated steers (613 kg mean bodyweight) were allocated to treatments CON and OG2 (n = 2) to monitor ruminal pH, volatile fatty acids, and NH3-N. Steers fed OG2 had greater (P < 0.01) average daily gain than CON; final liveweight for OG2 steers was significantly higher than both CON and OG1 steers. Although variations in plasma haematocrit and alkaline phosphatase were they did not affect animal performance. Dressing percentage was not affected by the experimental diets but OG2 steers had greater (P < 0.05) marbling scores. Although rib-eye area was numerically greater for OG1 and OG2 than CON steers (8% and 14%), these differences were not significant statistically (P = 0.3493). Intramuscular lipid content of Longissimus dorsi muscle was not significantly increased by OG supplementation but of the intramuscular fatty acids, contributions of vaccenic and α-linolenic acids decreased (P < 0.05). Linoleic acid content was lowest (P < 0.05) for OG1 steers. A no significant decrease in conjugated linoleic acid was detected when more OG was supplemented. No treatment differences in the contributions of eicosapentaenoic acid, docosahexaenoic acid, monounsaturated fatty acids, polyunsaturated fatty acids, saturated fatty acids, n-6 or n-3 to intramuscular fatty acids were detected although the n-6 : n-3 resulted numerically higher (11% and 23%) for OG1 and OG2 steers than CON steers. Rumen pH, NH3-N and volatile fatty acids were not significantly altered by OG supplementation. Supplementing diets of cattle grazing OP improved performance without rumen digestion impairs or inducing substantial changes in the lipid profile of intramuscular fat. Thus, OG supplementation would be expected to improve the efficiency of cattle grazing of OP without substantial changes to ruminal measurements or the lipid profile of beef.
In vitro rumen fermentation characteristics of goat and sheep supplemented with polyunsaturated fatty acids
Authors: Candyrine S. C. L. , Jahromi M. F. , Ebrahimi M. , Liang J. B. , Goh Y. M. , Abdullah N.
Published: May 2016

An in vitro gas-production study was conducted to compare differences in rumen fermentation characteristics and the effect of supplementation of 4% linseed oil as a source of polyunsaturated fatty acids on the rumen fermentation profile in rumen fluid collected from goats and sheep. Rumen fluid for each species was obtained from two male goats of ~18 months old and two sheep of similar sex and age fed the similar diet containing 30% alfalfa hay and 70% concentrates. The substrate used for the fermentation was alfalfa hay and concentrate mixture (30:70) without (control) and with addition of linseed oil. The experiment was a two (inoculums) × two (oil levels) factorial experiment, with five replicates per treatment, and was repeated once. Rumen fermentation characteristics, including pH, fermentation kinetics, in vitro organic matter digestibility (IVOMD), volatile fatty acid (VFA) production and microbial population were examined. Results of the study showed that gas-production rate (c), IVOMD, VFA production and population of total bacteria and two cellulolytic bacteria (Ruminococus albus and Butyrivibrio fibrisolvens) from rumen fluid of goat were significantly (P < 0.05) higher than those of samples from sheep. Irrespective of sources of inoculums, addition of oil did not affect fermentation capacity, IVOMD and total VFA production. The higher B. fibrisolvens population (associated with bio-hydrogenation) in rumen fluid of goat seems to suggest that polyunsaturated fatty acids are more prone to bio-hydrogention in the rumen of goat than in sheep. This assumption deserves further investigation.
Prodrug Micelles Based on Norbornene-Functional Poly(lactide)s Backbone for Redox-Responsive Release of Paclitaxel
Authors: Wang Ji , Yan Jing , Zhou Huicong , Huang Haikang , Zhang Xuefei , Tang Haoyu
Published: May 2016

Norbornene-functional poly(lactide)s backbone-based amphiphilic copolymer, P(LA-g-mOEG)-b-P(LA-SS-COOH), was synthesized as the polymeric scaffold and paclitaxel (PTX) was directly conjugated to the carboxyl groups of the amphiphilic copolymer to obtain redox-responsive P(LA-g-mOEG)-b-P(LA-SS-PTX) prodrugs. The dynamic light scattering and transmission electron microscopy analyses showed that P(LA-g-mOEG)-b-P(LA-SS-PTX) self-assembled into prodrug micelles with a diameter of 60–70 nm and a low polydispersity in aqueous solution. Remarkably, in vitro release studies revealed that 80 % of PTX was released in 72 h under a reductive environment, whereas only 23 % of PTX was released in 72 h under non-reductive conditions. In addition, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays showed that P(LA-g-mOEG)-b-P(LA-SS-PTX) prodrug micelles retained high anti-tumour activity while polymer carriers were non-toxic up to a tested concentration of 1.0 mg mL–1. These redox-responsive prodrug micelles have tremendous potential for anti-tumour drug delivery.
Arsenic adsorption onto aluminium-substituted goethite
Authors: Tufo Ana E. , dos Santos Afonso María , Sileo Elsa E.
Published: May 2016

Environmental contextGoethite, commonly found in soils, is often partially substituted by Al and strongly influences the mobility of arsenic in the environment. The adsorption of AsV onto goethites with increasing Al substitution was explored, finding that Al incorporation decreases AsV sorption per gram of adsorbent, and that a low level of Al incorporation enhances the adsorption per unit area. Structures of the complexes formed between AsV and the oxy(hydr)oxide surface, at different pH values, are proposed by studying the changes in the surface charges of the adsorbed and non-adsorbed substituted and non-substituted goethites. AbstractAluminium and iron oxy(hydr)oxides in nature are often partially substituted by other elements and strongly influence the mobility of arsenic in the environment. Because goethite is commonly found in soils, and the oxide is easily substituted, in the present work, the adsorption of AsV onto several Al-substituted goethites was explored in order to determine how substitution affects the adsorption process. Three samples with increasing Al content (GAl0, GAl3.78 and GAl7.61) were prepared and fully characterised. The variations in AsV adsorption under different conditions, as well as the variations of the particle surface charge, were analysed. The results showed that the removal capacity of Al-goethites is determined by the Al content. The adsorption maxima per gram followed the trend GAl0> GAl3.78> GAl7.61, indicating that Al incorporation decreases AsV sorption. Adsorption per surface area decreased in the order GAl3.78> GAl0> GAl7.61, implying that a small incorporation of Al enhances the adsorption properties of the surface. The stoichiometry of the probable surface complexes formed with the contaminant at different pH values is proposed, by analysis of all the experimental results obtained before and after AsV adsorption. These surface complexes were used to fit the experimental data with good agreement, and the formation and acidity constants were also estimated.