bluuebunny/crossref_metadata_2025 huggingface dataset:
Pressure effects on the charge carrier transportation of polycrystalline LiCr0.35Mn0.65O2
Authors: Hu Tingjing , Cui Xiaoyan , Yang Jie , Han Yonghao , Liu Hongwu , Gao Chunxiao , Du Fei , Chen Gang
Published: March 2011

LiCr0.35Mn0.65O2 powders were investigated by using in situ impedance spectroscopy under high pressure. The impedance spectroscopy of the Nyquist representation showed two overlapped arcs in the complex impedance plane which corresponded to the electrical transportation of grain and grain boundary respectively. By using the representation of Z ″/f versus Z ′, the resistance and the relaxation frequency of grain and grain boundary were obtained under different pressures. It was found that at every phase transition region, both the resistance and the relaxation frequency of grain and grain boundary changed discontinuously. Pressure decreases the effective scattering section of grain and grain boundary to the charge carriers obviously and makes their transport easier. The variation of defects in the grain boundary region leads the sample resistance in the decompression process is much lower than that in the compression process. This indicates the pressure treatment has a positive contribution to the electrochemical performance of LiCr0.35Mn0.65O2. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High pressure impedance spectroscopy of CdS nanocrystals
Authors: Ren Wanbin , Han Yonghao , Liu Cailong , Wang Yue , Liu Bao , Hu Tingjing , Cui Xiaoyan , Gao Chunxiao
Published: March 2011

Impedance spectroscopy of CdS nanocrystals (100 nm in diameter on average) was studied with the applied pressure up to 25 GPa using Solartron 1260 Impedance/Gain‐Phase Analyzer in diamond anvil cell (DAC). The change in complex impedance related to the phase transition from wurtzite to rock salt was observed.

Two distinct relaxation mechanisms were also identified. The effective scattering section of the grain boundary to charge carriers can be weakened under compression, which leads to the decrease of grain boundary resistance (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The ground electronic state of TiS2: experimental and theoretical studies
Authors: Liu Bao , Yang Jie , Liu Cailong , Hu Tingjing , Han Yonghao , Gao Chunxiao
Published: March 2011

An investigation of TiS2 electronic structure was conducted using a first‐principles calculation based on density functional theory (DFT). The results showed that there is indirect S3p ‐Ti3d band overlaps in ground electronic structure of TiS2. The measurements of resistivity and Hall effect were used to characterize the electrical transport behavior of TiS2 under ground state. Both theoretical and experimental results supported that TiS2 within ground state is a semimetal (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of grain boundary on resistance change in powdered ZnS under high pressure by in situ electrical impedance measurements
Authors: Wang Yue , Liu Cailong , Gao Yang , Wang Chunjie , Liu Bao , Hu Tingjing , Ren Wanbin , Han Yonghao , Gao Chunxiao
Published: March 2011

The effect of grain boundary on resistance in powdered ZnS under high pressure has been investigated by alternating current (ac) impedance spectrum method. Qualitative analysis indicated that the phase transition is accompanied by the shape transition of impedance spectrum which changed from two‐arc‐type to oblate‐like arc at 14.1 GPa. Above 11.0 GPa, the change of resistance is mainly contributed by grain boundary, and the residual resistance in rock‐salt phase ZnS is also comes from the grain boundary effect (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure modifications of oxide‐confined GaInNAs VCSELs for the second‐generation optical‐fibre communication
Authors: Sarzała Robert P. , Nakwaski Włodzimierz
Published: March 2011

For the second‐generation optical‐fibre communication, lasing sources emitting stable single‐fundamental‐mode (SFM) 1.3‐μm radiation are required. Then oxide‐confined GaAs‐based GaInNAs quantum‐well (QW) vertical‐cavity surface‐emitting lasers (VCSELs) seem to be the best solution. But possibility to reach their efficient 1.3‐μm low‐threshold SFM operation is usually questionable. Therefore the comprehensive fully self‐consistent simulation VCSEL model is used to find the most promising VCSEL structure for this application. It has been concluded from our analysis, that the best performance may be reached in the VCSEL structure in which the proper detuning of the cavity mode towards longer wavelengths and the proper step‐like active‐region QW structure are simultaneously applied. Then the stable 1.3‐μm SFM operation is reached for temperatures exceeding 305 K in the relatively large VCSEL with the 12‐μm diameter activity region. Its threshold current is only somewhat higher than 6 mA at the ambient temperature of 350 K. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The electrode factor on the accuracy of electrical resistivity measurement in diamond anvil cell
Authors: Wu Baojia , Han Yonghao , Peng Gang , Huang Xiaowei , Liu Cailong , Jin Fengxi , Gao Chunxiao
Published: March 2011

The four‐point method is widely used to determine the electrical resistivity of materials. Using finite element analysis (FEA) to simulate the distribution of the steady current field in sample, we illuminate the electrode factor on accurate resistivity measurement under high pressure in a diamond anvil cell (DAC). The result reveals that the measurement error is close dependent on the size and the resistivity of electrode. In order to minimize the measurement errors and improve the measurement accuracy, reducing the electrode size and increasing the electrode resistivity is a better choice. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of InN/In0.73Ga0.27N multiple quantum wells studied by spectroscopic ellipsometry
Authors: Ben Sedrine N. , Darakchieva V. , Lindgren D. , Monemar B. , Che S. B. , Ishitani Y. , Yoshikawa A.
Published: March 2011

In this work we study the optical properties of two high quality fifty‐periods of In‐polarity InN/In0.73Ga0.27N MQWs samples, grown by radio‐frequency plasma‐assisted molecular beam epitaxy, with different well (0.5‐1 nm) and barrier thicknesses (3‐4 nm). We employ spectroscopic ellipsometry at room temperature in the energy range from 0.6 to 6 eV, and incidence angles of 60 and 70°. Ellipsometric data were successfully modelled using the model dielectric function approach and a multilayer model assuming the MQWs as a homogeneous layer. The E0, A and E1 MQWs transition energies were determined and found to exhibit a blueshift with decreasing the well thickness. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
I‐V characterization of a staircase quantum well infrared photodetector
Authors: Nutku Ferhat , Arıkan M. Çetin , Erol Ayşe , Ergün Yüksel , Kendirlik E. Metin
Published: March 2011

In this work, a quantum well infrared photodetector structure which consists of three different well thicknesses with three different barrier compositions producing a staircase‐like conduction band profile with the reputation of 30 periods has been investigated. Dark current measurements have been done at the range from 6 K to 290 K temperature. Activation energies of the carriers have been obtained from the temperature dependence of the I‐V measurements. The change of the activation energy with bias voltage has also been obtained. From the activation energy at zero bias and calculated quasi Fermi energy, barrier heights of the quantum wells and ground state energies were obtained. All obtained ground state energies have been found to be consistent with the results obtained from calculations with the transfer matrix method. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tight binding modeling of electronic properties of III‐V based heterostructures
Authors: Akıncı Özden , Hakan Gürel H. , Ünlü Hilmi
Published: March 2011

In this work, we present second nearest neighbour (2NN) sp3s* and nearest neighbour (NN) sp3d5s* tight binding calculations, with spin‐orbit coupling to calculate the composition, temperature, pressure and strain effects on the electronic properties (e.g., band structure, density of states, band gaps and band widths) of GaAs, GaP, GaAN and AlN III‐V binaries and ternary GaPN. The results are compared with those of density functional theory for GaN. Our results are in good agreement with experiment for fundamental band gaps and electron effective masses. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of the effects of conduction band fluctuations caused by nitrogen clustering in GaInNAs materials
Authors: Sun Xiao , Rorison Judy M.
Published: March 2011

It has been observed experimentally that the band edge photoluminescence of GaInNAs Quantum well (QW) materials is broadened resulting from band‐tailing, localised states or conduction band edge fluctuations. In this paper we develop a model for N compositional fluctuations causing conduction band edge fluctuations which localise the electrons into the resulting quantum dots (QDs). The electron dynamics in the QDs and QW states are examined using a rate equation approach and the carrier populations presented as a function of barrier height and temperature. This mechanism could lead to broad gain in GaInAsN QW structures which could be useful for broad band SOAs for optical communications (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical field and temperature effects in 2D‐2D resonant tunneling diodes based on cubic InGaN/AlGaN
Authors: Bhouri A. , Yahyaoui N. , Debbichi M. , Mejri H. , Lazzari J.‐L. , Said M.
Published: March 2011

The present work reports on a study of the electron transport in a 2D‐2D resonant tunneling diode based on strained Al0.3Ga0.7N/In0.2Ga0.8N/Al0.3Ga0.7N quantum wells embedded between relaxed n‐Al0.15Ga0.85N/strained In0.2Ga0.8N emitter and collector contacts. The epilayers are assumed to be with cubic crystal structure to avoid the effects of spontaneous and piezoelectric polarization fields. The aluminum composition in both the injector and collector contacts is taken relatively weak, but large band offsets are achieved at the boundary of the preconfinement wells. The heterostructure modeled is aimed to operate at high biases and at elevated temperatures. Calculations of the band edges and quantum‐bound states were made using a self‐consistent solver of the Schrödinger and Poisson equations. Obtained results revealed: (i) a charge transfer occurs due to a resonant tunneling through a double barrier, (ii). A special attention is paid to the effects of resonant tunneling and thermal activation on the charge transfer. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study of InxAl1‐xN/ZnO and InxGa1‐xN/ZnO strained quantum well lasers
Authors: Djellal A. , Kadri A. , Gil B. , Bretagnon T. , Zitouni K.
Published: March 2011

We perform a theoretical study of InxAl1‐xN/ZnO and InxGa1‐xN/ZnO strained Quantum Well (QW) Lasers oriented along the non‐polar A‐plane axis. In order to determine the energy band‐offsets in both heterostructures as a function of alloy composition, we use the ab‐initio method to compute the total energies of these systems. Then, we use the k·P method within the envelop function formalism to study conduction and valence energy subband structures for various alloy compositions and well widths. Finally, we calculate the Laser gain for such strained QW heterostructures. Our results show that type I heterostructures can be made with two kind of systems: InxGa1‐xN/InxAl1‐xN/ZnO and InxGa1‐xN/InyGa1‐yN/ZnO where InxGa1‐xN is the QW in both cases. These heterostructures are lattice‐matched along A‐plane axis at x=32% in InxAl1‐xN/ZnO and x=17% in InxGa1‐xN/ZnO. However, because of the anisotropy of the built‐in strain at the interface, they are still slightly compressively strained along c‐axis. Pure tensile strain or pure compressive can be achieved only at In‐content values well below or well above these critical values, respectively. Our results are compared with various theoretical and experimental values, and quite good agreement is found. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
DFT calculation for green chemical catalyst with hydroxyl group supported on S‐terminated GaN(0001)
Authors: Yokoyama Mami , Murayama Tatsunori , Tsukamoto Shiro , Ishii Akira
Published: March 2011

A novel function of nitried‐based semiconductor is successfully developed for organic synthesis, in which palladium supported on the surface of S‐terminated GaN(0001) serves as a unique green chemical catalyst. In this study we determined the structure of OH on Pd‐catalyst supported on Sterminated GaN(0001) surface by means of the density functional theory (DFT) within a Local Density Approximation (LDA). (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fucoidan from Undaria pinnatifida Induces Apoptosis in A549 Human Lung Carcinoma Cells
Authors: Boo Hye‐Jin , Hyun Jae‐Hee , Kim Sang‐Cheol , Kang Jung‐Il , Kim Min‐Kyoung , Kim Sun‐Yeou , Cho Heeyeong , Yoo Eun‐Sook , Kang Hee‐Kyoung
Published: March 2011

Fucoidan, a sulfated polysaccharide, has various biological activities, such as anticancer, antiangiogenic and antiinflammatory effects; however, the mechanisms of action of fucoidan on anticancer activity have not been fully elucidated. The anticancer effects of fucoidan from Undaria pinnatifida on A549 human lung carcinoma cells were examined. Treatment of A549 cells with fucoidan resulted in potent antiproliferative activity. Also, some typical apoptotic characteristics, such as chromatin condensation and an increase in the population of sub‐G1 hypodiploid cells, were observed. With respect to the mechanism underlying the induction of apoptosis, fucoidan reduced Bcl‐2 expression, but the expression of Bax was increased in a dose‐dependent manner compared with the controls. Furthermore, fucoidan induced caspase‐9 activation, but decreased the level of procaspase‐3. Cleavage of poly‐ADP‐ribose polymerase (PARP), a vital substrate of effector caspase, was found. The study further investigated the role of the MAPK and PI3K/Akt pathways with respect to the apoptotic effect of fucoidan, and showed that fucoidan activates ERK1/2 in A549 cells. Unlike ERK1/2, however, treatment with fucoidan resulted in the down‐regulation of phospho‐p38 expression. In addition, fucoidan resulted in the down‐regulation of phospho‐PI3K/Akt. Together, these results indicate that fucoidan induces apoptosis of A549 human lung cancer cells through down‐regulation of p38, PI3K/Akt, and the activation of the ERK1/2 MAPK pathway. Copyright © 2011 John Wiley & Sons, Ltd.
Evaluation of the comparability of spectra generated using a tuning point protocol on twelve electrospray ionisation tandem‐in‐space mass spectrometers
Authors: Champarnaud E. , Hopley C.
Published: March 2011

Product ion spectra produced by collision‐induced dissociation (CID) in tandem mass spectrometry can yield important structural information on organic compounds which can aid in their identification. However, differences in experimental conditions may have a strong effect on the degree of product ion formation and therefore on the features observed in product ion spectra. For this reason, a common approach for library building is the acquisition of several spectra, typically between 5 and 10, each at a different collision energy level. In this study, the use of an alternative approach was investigated, where a tuning point protocol was applied to tune the instruments in an attempt to standardise CID conditions prior to data acquisition. With this approach, the acquisition of a single mass spectrum was sufficient. The stability of the tuning point was investigated and the choice of a commercially available search package to assess spectral comparability was discussed. Finally, the product ion spectra of 33 compounds were acquired on twelve tandem‐in‐space instruments, including nine triple quadrupoles, one hybrid triple quadrupole linear ion trap and two quadrupole time‐of‐flight mass spectrometers, resulting in 2178 spectral comparisons being carried out. The results from the spectral comparisons suggest that the use of a tuning point enables the standardisation of the experimental conditions that affect the degree of product ion formation. Indeed, 84.5% of the comparisons demonstrated a good degree of spectral agreement with match scores greater than 700, which we believe is the minimum score for a tentative library match. Copyright © 2011 John Wiley & Sons, Ltd.
Complexation between the fungicide tebuconazole and copper(II) probed by electrospray ionization mass spectrometry
Authors: Dytrtová Jana Jaklová , Jakl Michal , Schröder Detlef , Čadková Eva , Komárek Michael
Published: March 2011

Electrospray ionization mass spectrometry (ESI‐MS) is used to probe the complex formation between tebuconazole (1) and copper(II) salts, which both are commonly used fungicides in agriculture. Experiments with model solutions containing 1 and CuCl2 reveal the initial formation of the copper(II) species [(1)CuCl]+ and [(1)2CuCl]+ which undergo reduction to the corresponding copper(I) ions [(1)Cu]+ and [(1)2Cu]+ under more drastic ionization conditions in the ESI source. In additional experiments, copper/tebuconazole complexes were also detected in samples made from soil solutions of various origin and different amount of mineralization. The direct sampling of such solutions via ESI‐MS is thus potentially useful for understanding of the interactions between copper(II) salts and tebuconazole in environmental samples. Copyright © 2011 John Wiley & Sons, Ltd.
Evidence for bias in measured δ15N values of terrestrial and aquatic organic materials due to pre‐analysis acid treatment methods
Authors: Brodie Chris R. , Heaton Tim H. E. , Leng Melanie J. , Kendrick Christopher P. , Casford James S. L. , Lloyd Jeremy M.
Published: March 2011

We investigate the effect of acid treatment methods on δ15N values from a range of environmental organic materials in the context of the increased application of ‘dual‐mode’ isotope analysis (the simultaneous measurement of δ13C and δ15N from the same acid‐treated sample). Three common methods are compared; (i) untreated samples; (ii) acidification followed by sequential water rinse (rinse method); and (iii) acidification in silver capsules (capsule method). The influence of capsule type (silver and tin) on δ15N is also independently assessed (as the capsule and rinse methods combust samples in different capsules; silver and tin, respectively). We find significant differences in δ15N values between methods and the precision of any one method varies significantly between sample materials and above the instrument precision (>0.3‰). The δ15N values of untreated samples did not produce the most consistent data on all sample materials. In addition, the capsule type appears to influence the measured δ15N value of some materials, particularly those combusted only in silver capsules. We also compare the new δ15N data with previously published δ13C data on the same materials. The response of δ13C and δ15N within and between methods and sample materials to acidification appears to be relatively disproportionate, which can influence the environmental interpretation of the measured data. In addition, statistical methods used to estimate inorganic nitrogen are shown to be seriously flawed. Copyright © 2011 John Wiley & Sons, Ltd.
Scalable, asynchronous, distributed eigen monitoring of astronomy data streams
Authors: Bhaduri Kanishka , Das Kamalika , Borne Kirk , Giannella Chris , Mahule Tushar , Kargupta Hillol
Published: March 2011

In this paper, we develop a distributed algorithm for monitoring the principal components (PCs) for next generation of astronomy petascale data pipelines such as the Large Synoptic Survey Telescopes (LSST). This telescope will take repeated images of the night sky every 20 s, thereby generating 30 terabytes of calibrated imagery every night that will need to be co‐analyzed with other astronomical data stored at different locations around the world. Event detection, classification, and isolation in such data sets may provide useful insights to unique astronomical phenomenon displaying astrophysically significant variations: quasars, supernovae, variable stars, and potentially hazardous asteroids. However, performing such data mining tasks is a challenging problem for such high‐throughput distributed data streams. In this paper, we propose a highly scalable and distributed asynchronous algorithm for monitoring the PCs of such dynamic data streams and discuss a prototype web‐based system PADMINI (Peer‐to‐Peer Astronomy Data Mining) which implements this algorithm for use by the astronomers. We demonstrate the algorithm on a large set of distributed astronomical data to accomplish well‐known astronomy tasks such as measuring variations in the fundamental plane of galaxy parameters. The proposed algorithm is provably correct (i.e., converges to the correct PCs without centralizing any data) and can seamlessly handle changes to the data or the network. Real experiments performed on Sloan Digital Sky Survey (SDSS) catalogue data show the effectiveness of the algorithm. © 2011 Wiley Periodicals, Inc. Statistical Analysis and Data Mining 2011
Application of 3 × 3 transformation matrix in the correction of three‐dimensional AFM image tilts through coordinate transformation
Authors: Adebayo Adedayo S. , Zhao Xue‐zeng , Wang Fei , Zhou Faquan
Published: March 2011

In atomic force microscopy (AFM), it is difficult to maintain samples in a perfect horizontal position on the piezoelectric stage of an AFM to obtain accurate measurement of surface features and to enhance the visual effect of topographic images. Correction of the tilted image therefore requires the use of an appropriate 3 × 3 transformation matrix which will transform the coordinates to simultaneously correct the tilt in both the x‐and y‐axes due to the three‐dimensional nature of AFM images. In this study, application of transformation matrix in three‐dimensions for the simultaneous correction of image tilts in both the x‐ and y‐axes by the method of coordinate transformation in three‐dimensions is presented. Application of the matrix in simultaneously correcting tilts in the x‐ and y‐axes of an AFM image is implemented by simulating an image assuming there are tilts in both the x‐ and y‐axes. Results of features measurement after transforming the coordinates with the matrix show the efficacy of the matrix. This will conveniently replace the line‐by‐line analysis done to remove tilts in AFM, which has been the practice long before now. It also has the advantage of correcting images by simultaneously removing tilts in both the x‐ and y‐axes as a veritable replacement of having to separately correcting tilts in images. This matrix can be used to transform coordinates in three‐dimensions to obtain accurate step height and linewidth in AFM images. SCANNING 33: 94–98, 2011. © 2011 Wiley Periodicals, Inc.
VM aware journaling: improving journaling file system performance in virtualization environments
Authors: Huang Ting‐Chang , Chang Da‐Wei
Published: March 2011

Journaling file systems, which are widely used in modern operating systems, guarantee file system consistency and data integrity by logging file system updates to a journal, which is a reserved space on the storage, before the updates are written to the data storage. Such journal writes increase the write traffic to the storage and thus degrade the file system performance, especially in full data journaling, which logs both metadata and data updates. In this paper, a new journaling approach is proposed to eliminate journal writes in server virtualization environments, which are gaining in popularity in server platforms. Based on reliable hardware subsystems and virtual machine monitor (VMM), the proposed approach eliminates journal writes by retaining journal data (i.e. logged file system updates) in the memory of each virtual machine and ensuring the integrity of these journal data through cooperation between the journaling file systems and the VMM. We implement the proposed approach in Linux ext3 in the Xen virtualization environment. According to the performance results, a performance improvement of up to 50.9journaling approach of ext3 due to journal write elimination. In metadata‐write dominated workloads, this approach could even outperform the metadata journaling approaches of ext3, which do not guarantee data integrity. These results demonstrate that, on virtual servers with reliable VMM and hardware subsystems, the proposed approach is an effective alternative to traditional journaling approaches. Copyright © 2011 John Wiley & Sons, Ltd.
Realizing BF Long Campaign Life and Stable Running by Burden Distribution Adjustment
Authors: Ce Shang , Jianwei Zhu , Yanhui Zhang
Published: March 2011

Adjusting Burden distribution is one of the most important and effective operations. In terms of fixed equipment, charging materials and blowing regulation, the inner gas flow utilization could be improved by adjusting the burden distribution to achieve a well‐state skull, good blast furnace (BF) performance and long campaign life. The No.1 BF (the effective volume is 3200 m3) was equipped with a bell‐less top, cast iron cooling staves in the hearth and copper cooling plates from the belly to the lower shaft respectively. Although the satisfied indexes have been reached since blow on, the fluctuation caused by the skull dropping off happened several times. This resulted in the lining temperatures varying greatly, the coke ratio increasing and the product quality deteriorating. It is considered the main reason for the operation regulation not matching the varied conditions with deteriorating materials and continuous lower temperatures of hot metal etc. A type of effective charging mode is introduced in the paper to complete the BF long‐term stable running and long operation.
CFD Modeling and Analysis of The Flow, Heat Transfer and Mass Transfer in a Blast Furnace Hearth
Authors: Guo Bao‐Yu , Yu Ai‐Bing , Zulli Paul , Maldonado Daniel
Published: March 2011

Understanding the complex phenomena in the BF hearth is essential to increasing furnace productivity and to extending furnace campaign. Numerical modeling provides a cost‐effective tool to obtain such knowledge. We have developed several continuum‐based mathematical/numerical models to simulate the flow, heat transfer and mass transfer in the lower part of BF and in the hearth. These models have generated an improved insight into the mechanisms for liquid drainage efficiency, lining erosion and wall protection in BF hearth under operational conditions. The current paper provides an overview of these studies, as well as dealing with three specific aspects: (a) Gas flow and pressure on the liquid surface, and its effect on the drainage characteristics; (b) Flow and temperature distributions of liquid iron in the hearth, and the temperature distribution in the refractories; and (c), Titania injection to form Ti(C,N)‐rich scaffolds on the hearth refractory surface, to protect the hearth from erosion.
The political economy of nuclear energy
Authors: Hultman Nathan E.
Published: March 2011

Despite a history of problems, nuclear power is being discussed as a potentially useful and appropriate electricity source for both developed and developing countries. For example, expanding nuclear power's share of electricity portfolios could reduce, relative to a fossil‐intensive baseline, greenhouse gas emissions that lead to climate change. Moreover, nuclear power has long been advocated as a route to energy security and indeed, for many of the nuclear nations, it could decrease dependence on oil imports under certain technological scenarios, such as an increased use of plug‐in hybrid vehicles. The nuclear industry argues that a new generation of reactors, representing a refinement of existing technology, will enable this expansion. Because of these new motivations, some advocates have applied the term ‘nuclear renaissance’ to the possibility of a rapid expansion of nuclear power to satisfy a projected growing global electricity demand, while simultaneously reducing greenhouse gas emissions. This article outlines the primary challenges that this unique energy source presents for such a renaissance. Like other technologies, nuclear is situated in a social and political–economic matrix that influences its evolution. After reviewing the basic aspects of the technology, I discuss the history of the existing nuclear fleet, then address the prospects for advanced and next‐generation nuclear technologies. I review the economics of nuclear power as it is currently deployed and the potential changes to these economics under potential future development. In examining future scenarios, I explore the effects of national and international policies on nuclear energy. WIREs Clim Change 2011 2 397–411 DOI: 10.1002/wcc.113

This article is categorized under:

The Carbon Economy and Climate Mitigation > Policies, Instruments, Lifestyles, Behavior

The Carbon Economy and Climate Mitigation > Future of Global Energy

Policy and Governance > Multilevel and Transnational Climate Change Governance
Quasi‐optimal power allocation based on ergodic capacity for wireless relay networks
Authors: Lin Fei , Luo Tao , Jiang Tao
Published: March 2011

Half‐duplex amplify‐and‐forward (AF) transmissions may result in insufficient use of degrees of freedom if they always use the cooperative mode regardless of the fading states. In this paper, we investigate the conditions under which cooperation offers better performance and the corresponding optimal power allocation during cooperation. Specifically, we first derive an expression of ergodic capacity and its upper bound for an AF cooperative communication system with n relay nodes. Secondly, we propose a novel quasi‐optimal power allocation (QOPA) scheme to maximize the upper bound of the derived ergodic capacity. For the QOPA scheme, the cooperative mode is only adopted when the channel gain of source‐to‐destination is worse than that of relay‐to‐destination. Moreover, we analyze the performance of the system with QOPA scheme when the relay moves, which is based on the random direction model, in a single‐relay wireless network. For a multi‐relay AF network, we compare the ergodic capacity and symbol error rate, corresponding to the proposed QOPA and equal power allocation schemes, respectively. Extensive simulations were conducted to validate analytical results, showing that both ergodic capacity and symbol error rate of the system with QOPA scheme are better than those of the system with equal power allocation scheme in a multi‐relay AF network. Copyright © 2011 John Wiley & Sons, Ltd.
The predictability of above roof wind resource in the urban roughness sublayer
Authors: Millward‐Hopkins J.T. , Tomlin A.S. , Ma L. , Ingham D. , Pourkashanian M.
Published: March 2011

The predictability of above roof wind resource (three‐dimensional mean wind speed) in the roughness and inertial sublayers over idealized urban arrays has been studied using data previously obtained from wind tunnel experiments and a validated large eddy simulation. Both uniform arrays and arrays of heterogeneous heights (representing suburban and more complex urban areas, respectively) were considered. Firstly, the spatial variation of the wind resource within the roughness sublayers over the more complex heterogeneous array was assessed, and suggestions for ideal rooftop turbine placement in this type of geometry were made. It was found that the spatially averaged wind profile can be considered to be a lower bound for the available wind resource at the most viable turbine locations. Secondly, available methods of estimating spatially averaged wind profiles above urban‐like surfaces were discussed, and bearing in mind the uncertainties inherent in these methods, a typical wind resource prediction methodology was followed. Significant uncertainties were found to occur at each stage of the prediction, but it was found that the errors occurring because of the typical methods used to parameterize surface aerodynamics are potentially the most significant. Therefore, to increase the accuracy of these prediction methodologies, it is necessary to improve the methods of parameterizing surface aerodynamics and estimating roughness sublayers spatial averages for urban‐like surfaces. Copyright © 2011 John Wiley & Sons, Ltd.
Variationen modulo 4–4+, 4+3–3+4–, 4–5+, 5–4+4–5+4–4+ bei Seltenerdcarbidhalogeniden
Authors: Mattausch Hansjürgen , Simon Arndt
Published: March 2011

The new compounds Pr8(C2)4Cl5 (1), Pr14(C2)7Cl9 (2), Pr22(C2)11Cl14 (3), Ce2(C2)Cl (4), La2(C2)Br (5), Ce2(C2)Br (6), Pr2(C2)Br (7), Ce18(C2)9Cl11 (8), and Ce26(C2)13Cl16 (9) were prepared by heating mixtures of LnX3, Ln and carbon or in an alternatively way LnX3, and “Ln2C3–x” in appropriate amounts for several days between 750 and 1200 °C. The crystal structures were investigated by X‐ray powder analysis (5–7) and/or single crystal diffraction (1–4, 8, 9). Pr8(C2)4Cl5 crystallizes in space group P21/c with the lattice parameters a = 7.6169(12), b = 16.689(2), c = 6.7688(2) Å, β = 103.94(1) °, Pr14(C2)7Cl9 in Pc with a = 7.6134(15), b = 29.432(6), c = 6.7705(14) Å, β = 104.00(3) °, Pr22(C2)11Cl14 in P21/c with a = 7.612(2), b = 46.127(9), c = 6.761(1) Å, β = 103.92(3) °, Ce2(C2)2Cl in C2/c with a = 14.573(3), b = 4.129(1), c = 6.696(1) Å, β = 101.37(3) °, La2(C2)2Br in C2/c with a = 15.313(5), b = 4.193(2), c = 6.842(2) Å, β = 100.53(3) °, Ce2(C2)2Br in C2/c with a = 15.120(3), b = 4.179(1), c = 6.743(2) Å, β = 101.09(3) °, Pr2(C2)2Br in C2/c with a = 15.054(5), b = 4.139(1), c = 6.713(3) Å, β = 101.08(3) °, Ce18(C2)9Cl11 in P$\bar{1}$ with a = 6.7705(14), b = 7.6573(15), c = 18.980(4) Å,α = 88.90(3) °, β = 80.32(3) °, γ = 76.09(3) °, and Ce26(C2)13Cl16 in P21/c with a = 7.6644(15), b = 54.249(11), c = 6.7956(14) Å, β = 103.98(3) ° The crystal structures are composed of Ln octahedra centered by C2 dumbbells. Such Ln6(C2)‐octahedra are condensed into chains which are joined into undulated sheets. In compounds 1–4 three and four up and down inclined ribbons alternate (4+4–, 4+3–3+4–, 4+4–3+4–4+3–), in compounds 8 and 9 four and five (4+5–, 5+4–4+5–4+4–), and in compounds 4–7 one, one ribbons (1+1–) are present. The Ln‐(C2)‐Ln layers are separated by monolayers of X atoms.
Obesity is a Predictor of Morbidity in 1,629 Patients Who Underwent Adrenalectomy
Authors: Kazaure Hadiza S. , Roman Sanziana A. , Sosa Julie A.
Published: March 2011

Background

We examined the impact of obesity on 30‐day outcomes of adrenalectomy using a multi‐institutional database.

Methods

Patients who underwent adrenalectomy in 2005–2008 according to the American College of Surgeons‐National Surgical Quality Improvement Project (ACS‐NSQIP) data set were grouped by body mass index (BMI): normal weight (BMI = 18.5–24.9 kg/m2), overweight (BMI = 25.0–29.9 kg/m2), obese (BMI = 30.0–34.9 kg/m2), and morbidly obese (BMI ≥ 35 kg/m2). Outcomes of the higher BMI groups were compared to those of the normal BMI group using χ2, analysis of variance (ANOVA), and multivariate regression.

Results

There were 1,629 patients in the study: 22% were normal weight, 31% overweight, 22.2% obese, and 24.7% morbidly obese. Compared to normal‐weight patients, obese and morbidly obese patients had a 12.5 and 16.7% increase in operation times (129 vs. 145 and 150 min, respectively, p ≤ 0.01) and sustained more wound complications (0.2 vs. 0.4 and 1.2%, p < 0.001), including superficial and deep wound infections (p < 0.001 and p < 0.01, respectively). Morbid obesity independently predicted overall complications (odds ratio [OR] 2.9, 95% confidence interval [CI]: 1.7–5.7), wound complications (OR 6.1, 95% CI: 2.0–18.9), and septic complications (OR 3.1, 95% CI: 1.1–8.8). Obesity independently predicted longer total time in the operating room (p < 0.006). There were no differences in rates of reoperation and length of hospital stay by BMI category.

Conclusion

Obesity is an independent risk factor that needs to be considered in surgical decisions regarding adrenalectomy. Morbidly obese adrenalectomy patients are particularly at risk for wound and septic complications.
Aggregation and Adsorption at the Air–Solution Interface of the Cetyltrimethyl Ammonium Tosylate With Two Poly(oxyethylene)–Poly(oxypropylene)–Poly(oxyethylene) Block Copolymers Aqueous Mixtures
Authors: Brigante Maximiliano , Schulz Pablo C.
Published: March 2011

The aqueous mixed systems (EO76PO30EO76) (TBCP8400)—cetyltrimethyl ammonium tosylate (CTAT), and (EO97PO69EO97) (TBCP12600)—CTAT were studied to determine both the bulk aggregation and the adsorbed monolayer at the air/water interface. Results were interpreted with the pseudophase separation model plus the regular solution theory for aggregates and monolayers. The behavior is different for TBCP8400–CTAT and TBCP12600–CTAT mixtures, but it is strongly non‐ideal in both cases. In bulk, TBCP8400–CTAT mixtures produce aggregates more close to CTAT micelles having TBCP8400 as a solubilizate than the inverse. At low CTAT content, the interaction is repulsive becoming attractive at high TBCP8400 content. The TBCP12600–CTAT aggregates strongly differ from the structure of both pure component micelles, and the interaction is always repulsive. In both cases, the interaction seems not to be cooperative but gradual. CTAT effect on copolymers aggregates seems to be more similar to that of a zwitterionic surfactant than to that of an ionic one. However, CTAT is not included in the aggregates as an ion pair, as revealed by the ionization degree results. It seems that cetyltrimethyl ammonium and tosylate ions have different effects on aggregates which in part are opposite. The adsorbed monolayers also show different behavior. In TBCP8400–CTAT system, the monolayer is mainly a CTAT one with inclusion of TBCP8400 as a monolayer‐soluble impurity. However, the inclusion of the non‐ionic surfactant alters the structure of the monolayer, which differs from that of the pure CTAT one. The area per adsorbed molecule (A0) is systematically higher than the ideal and computed ones. The system TBCP12600–CTAT shows a monolayer composition which is almost the same that the overall surfactant mixture composition, and the monolayer structure differs from both the pure‐TBCP12600 and the pure‐CTAT monolayers ones. The experimental A0 values are systematically lower than the ideal and the computed ones. Then, in both cases the A0 values for the pure components do not remain invariable in the mixed monolayer. The phenomenon is interpreted on the basis of the conformation of the copolymers adsorbed at the air/solution interface.
Micellization of Beta‐Carotene from Soy‐Protein Stabilized Oil‐in‐Water Emulsions under In Vitro Conditions of Lipolysis
Authors: Malaki Nik Amir , Wright Amanda J. , Corredig Milena
Published: April 2011

The details of the interfacial changes occurring during digestion of an oil‐in‐water emulsion stabilized with soy protein isolate (SPI) and the impact of the changes on lipolysis and subsequent release of β‐carotene (BC) were studied using a two‐step in vitro digestion model with varying composition containing bile salts (BS), colipase (COL), phospholipids (PL), and phospholipase A2 (PLA2). The hydrolysis of the interfacial layer by pepsin resulted in significant changes in the emulsion droplet size distribution. The introduction of bio‐surfactants (BS and PL), in combination with the release of lipid digestion products in the duodenal stage, resulted in re‐emulsification of the oil droplets. During this stage a significant increase in the negative charge of the oil droplets from −40 to −70 mV, was also observed, indicating significant changes in interfacial composition. The activity of the pancreatic triglyceride lipase (PTL), as monitored by the liberation of free fatty acids, was largely governed by the composition of digestive fluids. In the presence of BS alone, lipid hydrolysis reached 66.1 ± 3.4%, while addition of PL inhibited lipolysis. Inclusion of PLA2 was found to increase the rate of lipolysis markedly, and the introduction of COL, along with BS, significantly increased the efficiency of the lipolysis such that a maximum lipid hydrolysis of 81.2 ± 1.2% was reached with about 50% transfer of BC to the mixed micelles.
Adsorption of Soy Protein Isolate in Oil‐in‐Water Emulsions: Difference Between Native and Spray Dried Isolate
Authors: Keerati‐u‐rai Maneephan , Wang Zebin , Corredig Milena
Published: April 2011

The purpose of this study was to determine the differences in the emulsifying properties of isolated soy protein prepared in the pilot plant (heated and spray dried) or in the laboratory (unheated and freeze‐dried), from the same soy flakes. When the thermal transitions were measured by micro‐calorimetry, the protein isolated in the pilot plant showed a very broad thermal transition, while the native isolate showed two distinct transition peaks, attributed to β‐conglycinin and glycinin denaturation. Electrophoretic analysis and protein assay of the soluble protein in the fractions revealed a significantly smaller amount of protein recovered in the centrifugal supernatant for the isolated soy protein prepared in the pilot plant than for the native protein. A larger amount of ions was recovered in the pilot plant isolate. However, the thermal treatment of the solutions increased the recovery of the pilot plant isolate proteins in the centrifugal supernatant, with an opposite effect for the native soy protein. A significantly larger amount of pilot plant isolated protein was needed to prepare emulsions with the same characteristics of those prepared with native soy protein. The emulsions prepared with pilot plant isolates showed much lower susceptibility to heating than those prepared with native protein.
The Legacy of Black Lynching and Contemporary Segregation in the South
Authors: DeFina Robert , Hannon Lance
Published: March 2011

Wacquant (2001) and others have argued that social control efforts directed at racial and ethnic minorities frequently shift institutional form and become more nuanced as societies modernize, even as the underlying function persists. This study examines the connection between southern lynching and housing segregation. We argue that legal, political, social and demographic changes in the south made lynching dysfunctional as a means of control. Among other more nuanced control mechanisms, modern housing segregation helped serve as a replacement. We test this proposition by relating historical southern black lynching rates to recent levels of segregation in southern MSAs. We find that an MSA's historical lynching rate is positively and significantly linked to the MSA's current segregation levels after accounting for standard determinants of segregation. Thus, segregation does not just occur generally throughout the south, but follows a very particular pattern based on past lynching rates. Our findings add to a growing literature on the legacy of lynching, such as studies examining contemporaneous variation in support for and use of capital punishment.
The role of immune semaphorins in multiple sclerosis
Authors: Okuno Tatsusada , Nakatsuji Yuji , Kumanogoh Atsushi
Published: March 2011

The nervous and immune systems have similar functional characteristics. Both have an intricate network of synaptic connections and an exquisite communication system that enable intercellular signal transduction. Although semaphorins were originally identified as guidance cues in neural development, accumulating evidence indicates that several semaphorins called ‘immune semaphorins’, such as Sema3A, 4A, 4D, 6D and 7A, are critically involved in various phases of the immune response by regulating immune cell–cell contacts or cell migration. In this review, we present recent knowledge on the functions of semaphorins and their receptors in the immune system and their potential roles in the pathogenesis of multiple sclerosis (MS), a representative CNS autoimmune disease, and its animal model, experimental autoimmune encephalomyelitis (EAE).
Risk conferring genes in multiple sclerosis
Authors: Nischwitz S. , Müller-Myhsok B. , Weber F.
Published: April 2011

Multiple sclerosis (MS) is characterized by inflammation, axonal and oligodendrocyte pathology and progressive neurological disability. Epidemiologic data indicate that MS may be caused by interplay of genetic and environmental factors. Large samples collected in cooperative efforts and new technologies such as high throughput single nucleotide polymorphism (SNP) genotyping allowed recently to discover non‐HLA genes associated with MS susceptibility that are mostly involved in the immune response. In addition, several studies indicate an effect of genetic variations on disease onset, progression and response to therapy. However, the polymorphisms discovered so far explain the genetic variation in MS only in part and are mostly common variants that have only low impact on MS susceptibility. Functional studies are required to validate the importance of the newly identified SNPs. Taking into account the interplay of genetic and environmental factors a combination of genome wide genotyping including HLA‐typing and genome wide expression profiling as well as a collection on relevant or putatively relevant environmental factors in patients well characterized clinically and by MRI is a promising way to identify new disease relevant biomarkers.
Pulsatile Flow Patterns and Wall Shear Stresses in Arch of a Turn-Around Tube With/Without Stenosis
Authors: Huang R. F. , Ho C.-Y. , Chen J.-K.
Published: March 2011

The temporal/spatial evolution processes of the flow pattern, velocity distribution, and wall shear stress of pulsatile water flows in the arch of 180o turn-around tubes with/without stenosis were experimentally studied by using the particle image velocimetry (PIV). Three transparent tubes made of glass were used: A tube without stenosis in the arch, a tube with a 25% stenosis at the inner wall of arch, and a tube with a 50% stenosis at the inner wall of arch. Here the percentage of stensis denoted the ratio between the stenosis height to inner diameter of arch in the diametral cross section across mid-arch of the central plane. The flow was provided by a pump which approximately simulated the pulsatile pressure waves of human heart beats. The systole to diastole time period ratio is set at 35%:65%. The Womersley parameter, Dean number, and time-averaged Reynolds number were 14, 2348, and 3500, respectively. In the arch of the turn-around tube without stenosis, no boundary layer separation was found during the systolic phase. The reverse flow and recirculation bubble appeared in the arch only during the diastolic phase. The inner wall of the arch experienced lower wall shear stress during the diastolic phase due to the formation of recirculation bubble and secondary flow. In the arch with stenosis, the boundary layer separated from the inner wall and formed a recirculation bubble downstream the stenosis during the systolic phase. Lower stenosis (25%) did not cause drastic variation of the wall shear stresses. At higher stenosis (50%), however, the wall shear stress around the inner wall downstream the stenosis became extraordinarily low, whereas the wall shear stress around the upstream region of the outer wall of the downstream branch of the tube became anomalously large.