bluuebunny/crossref_metadata_2025 huggingface dataset:
Responses of Metalloporphyrin‐Based Ion‐Selective Electrodes to pH
Authors: Inoue Takuya , Baba Toshiyuki , Yuchi Akio
Published: November 2010

The ISEs based on [M(tpp)Cl] (M: Al, Ga, In, Mn, Fe; H2tpp: tetraphenylporphin) had pH responses across their respective pH ranges, which had some correlation with the pH ranges of the two‐phase hydrolysis. Such pH responses are ascribed to the phase boundary potentials relating to the acid‐base pairs of [M(tpp)(H2O)]+ and [M(tpp)(OH)] and/or [M2(tpp)2O]. The potential responses of the In and Fe complexes had the upper limitation to pH of 90 % hydrolysis, whereas those of the Al and Ga complexes had the extension to at least pH 12, indicating stable existence of [M(tpp)(H2O)]+ even in contact with strongly alkaline solutions.
The Electrochemical Behavior of Gold Nanoparticle‐Tantalum(V) Phthalocyanine Composites: Applications Towards the Electroanalysis of Bisphenol A
Authors: Chauke Vongani P. , Chidawanyika Wadzanai , Nyokong Tebello
Published: November 2010

The formation of gold nanoparticle (AuNP) composites with tantalum phthalocyanines (TaPc) complexes {1a and 1b (Figure 1)} is reported. The TaPc‐AuNPs conjugates were characterised by atomic force microscopy (AFM) and transmission electron microscopy. The AFM analyses show that conjugates of TaPc with AuNPs are more aggregated when compared to AuNPs alone. The conjugates and TaPc complexes were immobilized on a gold electrode by drop and dry method and these were characterized by electrochemical impedance spectroscopy. The charge transfer behaviour of AuNPs was enhanced in the presence of TaPc complexes. All the modified electrodes showed electrocatalytic oxidation of bisphenol A. The limits of detection for complexes 1a and 1b were 4.78×10−10 and 2.76×10−10 mol L−1, respectively.
Numerical pricing of American options under infinite activity Lévy processes
Authors: Rambeerich Nisha , Tangman Desire Yannick , Bhuruth Muddun
Published: November 2010

Under infinite activity Lévy models, American option prices can be obtained by solving a partial integro‐differential equation (PIDE), which has a singular kernel. With increasing degree of singularity, standard time‐stepping techniques may encounter difficulties. This study examines exponential time integration (ETI) for solving this problem and the performance of this scheme is compared with the Crank–Nicolson (CN) method and an implicit–explicit method in conjunction with an extrapolation (IMEX‐Extrap), in terms of computational speed and convergence orders. These findings indicate that ETI is faster and more accurate among PIDE‐based methods for solving the system of ordinary differential equations resulting from spatial discretization of the PIDE. For very singular problems, it is shown that the IMEX‐Extrap scheme becomes unfavorable compared with the other schemes as it is relatively more time consuming and the global convergence deteriorates from quadratic to linear, whereas the ETI scheme yields both point‐wise and global quadratic convergence. For illustration, under the infinite variation process, the IMEX‐Extrap achieves a precision of the order of 10−4 in 663.016 s, whereas for the same set of parameters, the CN method and the ETI scheme reach an accuracy of the order of 10−5 in 237.891 s and 22.772 s, respectively. © 2010 Wiley Periodicals, Inc. Jrl Fut Mark 31:809–829, 2011
Distributed modelling of future changes in hydrological processes of Spencer Creek watershed
Authors: Sultana Zakia , Coulibaly Paulin
Published: November 2010

The hydrologic impact of climate change has been largely assessed using mostly conceptual hydrologic models. This study investigates the use of distributed hydrologic model for the assessment of the climate change impact for the Spencer Creek watershed in Southern Ontario (Canada). A coupled MIKE SHE/MIKE 11 hydrologic model is developed to represent the complex hydrologic conditions in the Spencer Creek watershed, and later to simulate climate change impact using Canadian global climate model (CGCM 3·1) simulations. Owing to the coarse resolution of GCM data (daily GCM outputs), statistical downscaling techniques are used to generate higher resolution data (daily precipitation and temperature series). The modelling results show that the coupled model captured the snow storage well and also provided good simulation of evapotranspiration (ET) and groundwater recharge. The simulated streamflows are consistent with the observed flows at different sites within the catchment. Using a conservative climate change scenario, the downscaled GCM scenarios predicted an approximately 14–17% increase in the annual mean precipitation and 2–3 °C increase in annual mean maximum and minimum temperatures for the 2050s (i.e., 2046–2065). When the downscaled GCM scenarios were used in the coupled model, the model predicted a 1–5% annual decrease in snow storage for 2050s, approximately 1–10% increase in annual ET, and a 0·5–6% decrease in the annual groundwater recharge. These results are consistent with the downscaled temperature results. For future streamflows, the coupled model indicated an approximately 10–25% increase in annual streamflows for all sites, which is consistent with the predicted changes in precipitation. Overall, it is shown that distributed hydrologic modelling can provide useful information not only about future changes in streamflow but also changes in other key hydrologic processes such as snow storage, ET, and groundwater recharge, which can be particularly important depending on the climatic region of concern. The study results indicate that the coupled MIKE SHE/MIKE 11 hydrologic model could be a particularly useful tool for understanding the integrated effect of climate change in complex catchment scale hydrology. Copyright © 2010 John Wiley & Sons, Ltd.
Biophysical characterization of ovine forestomach extracellular matrix biomaterials
Authors: Floden Evan W. , Malak Sharif F. F. , Basil‐Jones Melissa M. , Negron Leonardo , Fisher James N. , Lun Stan , Dempsey Sandi G. , Haverkamp Richard G. , Ward Brian R. , May Barnaby C. H.
Published: November 2010

Ovine forestomach matrix (OFM) is a native and functional decellularized extracellular matrix biomaterial that supports cell adhesion and proliferation and is remodeled during the course of tissue regeneration. Small angle X‐ray scattering demonstrated that OFM retains a native collagen architecture (d spacing = 63.5 ± 0.2 nm, orientation index = 20°). The biophysical properties of OFM were further defined using ball‐burst, uniaxial and suture retention testing, as well as a quantification of aqueous permeability. OFM biomaterial was relatively strong (yield stress = 10.15 ± 1.81 MPa) and elastic (modulus = 0.044 ± 0.009 GPa). Lamination was used to generate new OFM‐based biomaterials with a range of biophysical properties. The resultant multi‐ply OFM biomaterials had suitable biophysical characteristics for clinical applications where the grafted biomaterial is under load. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Mitogen‐activated protein kinase in endothelin‐1‐induced cardiac differentiation of mouse embryonic stem cells
Authors: Chen Ming , Lin Yong‐Qing , Xie Shuang‐Lun , Wang Jing‐Feng
Published: November 2010

Endothelin‐1(ET‐1) is a potent vasoconstrictor involved in the development of cardiovascular diseases and is an important regulator of heart development. However, the role of ET‐1 in cardiac differentiation of mouse embryonic stem cells (mESCs) and the underlying molecular mechanisms remain poorly understood. In the present study, we showed that ET‐1 significantly up‐regulated gene expression of the cardiac specific transcriptional factors Nkx2.5, GATA4, and conduction system specific marker CX40, with no affect on the gene expression of α‐MHC and β‐MHC in cardiac differentiation of mESCs. The percentage of beating embryoid bodies (EB) and the Troponin T (TnT) positive area in total EBs was unchanged following ET‐1 treatment, while the percentage of spindle cells that stained positively with TnT was increased in the presence of ET‐1. Further investigation indicated that the percentage of beating EBs and the TnT positive area were decreased by the extracellular signal‐related kinases (ERK)‐1/2 inhibitor U0126 and the p38 inhibitor SB203580, but not by the Jun amino‐terminal kinases (JNK) inhibitor SP600125. Inhibition of ERK1/2, p38, and JNK pathways also blocked the up‐regulation of Nkx2.5 and GATA4 by ET‐1, however only inhibition of the ERK1/2 pathway had negatively effects on the increase in CX40 expression in response to ET‐1. ET‐1 induced an increase in the percentage of spindle cells was also inhibited by U0126. Our results suggest that ET‐1 plays a significant role in the cardiac differentiation of mESCs, especially in those cells committed to the conduction system, with the ERK1/2 pathway playing a critical role in this process. J. Cell. Biochem. 111: 1619–1628, 2010. © 2010 Wiley‐Liss, Inc.
Different apoptotic effects of wogonin via induction of H2O2 generation and Ca2+ overload in malignant hepatoma and normal hepatic cells
Authors: Wei Libin , Lu Na , Dai Qinsheng , Rong Jingjing , Chen Yan , Li Zhiyu , You Qidong , Guo Qinglong
Published: November 2010

Wogonin, a major active constituent of Scutellaria baicalensis, possesses potent anticancer activities both in vivo and in vitro. This paper describes the different apoptotic effects of wogonin in HepG2 and L02 cells and the possible mechanism for the differences. Through DAPI staining, Annexin‐V/PI double‐staining assay, JC‐1 detection and the expressions of the key apoptotic proteins, we find that wogonin prefers to induce apoptosis in HepG2 cells through the mitochondrial pathway, while has much less effects on L02 cells. Moreover, overexpression of Bcl‐2 can block wogonin‐induced apoptosis in HepG2 cells. To illustrate the specific selective mechanism of wogonin in apoptosis induction, H2O2, ·O and Ca2+ are measured by 2′,7′‐dichlorfluorescein‐diacetate, dihydroethidium and Flou‐3 AM assay, respectively. The results show that the different apoptotic effects of wogonin in HepG2 and L02 cells are due to the different regulations to the redox balance of reactive oxygen species and the Ca2+ release from endoplasmic reticulum. IP3R‐sensitive Ca2+ channels are the key targets of the wogonin‐increased H2O2. Besides, the activation of PLCγ1 plays as a bridge between H2O2 signal molecules and Ca2+ release. Taken together, wogonin preferentially kills hepatoma cells by H2O2‐dependent apoptosis triggered by Ca2+ overload. The results reveal that wogonin is a competitive anticancer drug candidate for the malignant hepatoma therapy. J. Cell. Biochem. 111: 1629–1641, 2010. © 2010 Wiley‐Liss, Inc.
PRL‐3 phosphatase and cancer metastasis
Authors: Al‐Aidaroos Abdul Qader O. , Zeng Qi
Published: November 2010

The deregulated expression of members of the phosphatase of regenerating liver (PRL) family has been implicated in the metastatic progression of multiple human cancers. Importantly, PRL‐1 and PRL‐3 both possess the capacity to drive key steps in metastatic progression. Yet, little is known about the regulation and oncogenic mechanisms of this emerging class of dual‐specificity phosphatases. This prospect article details the involvement of PRLs in the metastatic cascade, the regulatory mechanisms controlling PRL expression, and recent efforts in the characterization of PRL‐modulated pathways and substrates using biochemical and high‐throughput approaches. Current advances and future prospects in anti‐cancer therapy targeting this family are also discussed. J. Cell. Biochem. 111: 1087–1098, 2010. © 2010 Wiley‐Liss, Inc.
Cartilage viability and catabolism in the intact porcine knee following transarticular impact loading with and without articular fracture
Authors: Backus Jonathon D. , Furman Bridgette D. , Swimmer Troy , Kent Collin L. , McNulty Amy L. , DeFrate Louis E. , Guilak Farshid , Olson Steven A.
Published: November 2010

Posttraumatic arthritis commonly develops following articular fracture. The objective of this study was to develop a closed joint model of transarticular impact with and without creation of an articular fracture that maintains the physiologic environment during loading. Fresh intact porcine knees were preloaded and impacted at 294 J via a drop track. Osteochondral cores were obtained from the medial and lateral aspects of the femoral condyles and tibial plateau. Chondrocyte viability was assessed at days 0, 3, and 5 postimpact in sham, impacted nonfractured, and impacted fractured joints. Total matrix metalloproteinase (MMP) activity, aggrecanase (ADAMTS‐4) activity, and sulfated glycosaminoglycan (S‐GAG) release were measured in culture media from days 3 and 5 posttrauma. No differences were observed in chondrocyte viability of impacted nonfractured joints (95.9 ± 6.9%) when compared to sham joints (93.8 ± 7.7%). In impacted fractured joints, viability of the fractured edge was 40.5 ± 27.6% and significantly lower than all other sites, including cartilage adjacent to the fractured edge (p < 0.001). MMP and aggrecanase activity and S‐GAG release were significantly increased in specimens from the fractured edge. This study showed that joint impact resulting in articular fracture significantly decreased chondrocyte viability, increased production of MMPs and aggrecanases, and enhanced S‐GAG release, whereas the same level of impact without fracture did not cause such changes. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:501–510, 2011
Potential‐induced Raman behavior of individual (R)‐di‐2‐naphthylprolinol molecules on a Ag‐modified Ag electrode
Authors: Luo Zhixun , Yang Wensheng , Luo Yi , Peng Aidong , Ma Ying , Fu Hongbing , Yao Jiannian , Loo Boon H.
Published: November 2010

The applicability of surface‐enhanced Raman spectroscopy is demonstrated to probe the adsorption behavior of individual molecules on a Ag electrode. High‐quality SERS spectra of (R)‐di‐2‐naphthylprolinol (DNP) were obtained from ultradilute solutions (10−12 M) on the Ag‐nanoparticle‐modified Ag electrode, which is attributed to the high electromagnetic (EM) effect of the SERS‐active system as well as to the strong adsorption and interaction of DNP molecules with Ag. The stable SERS spectra present remarkable potential dependence, which gives evidence for the behavior of individual DNP molecules on the Ag surface. Based on statistical analysis for the probability of DNP molecules located in ‘hot spots’, we propose an SERS mechanism for individual molecules in the electrode system, in combination with the hot‐spot model and orientation of the probe molecules. Copyright © 2010 John Wiley & Sons, Ltd.
Some notes on the economic assessment of land degradation
Authors: Requier‐Desjardins M. , Adhikari B. , Sperlich S.
Published: November 2010

Economic factors are an important direct and indirect driver of desertification and land degradation, associated with market failures and the lack of appropriate economic policies to address these failures. Hence, economic and political instruments and mechanisms are required to modify the market in such a way that it encourages land owners to invest in sustainable land management (SLM) options and thereby help to combat land degradation. This article synthesizes the economic aspects of land degradation, first in a rather general way. It then discusses existing valuation methods used to assign economic values to land degradation including the resulting problems which in turn hamper cost–benefit analyses. Finally, based on these points a brief review is given of potential financial mechanisms to combat land degradation and promote SLM. The paper argues that valuation of the economic costs of land degradation and desertification would increase awareness of the extent of the land degradation phenomenon and its impacts on rural development and agriculture. This could also be a useful tool for decision‐making on sectoral orientations for development assistance targeted at desertification, land degradation and drought. Copyright © 2010 John Wiley & Sons, Ltd.
Imaging left ventricular tissue mechanics and hemodynamics during supine bicycle exercise using a combined tagging and phase‐contrast MRI pulse sequence
Authors: Sampath Smita , Derbyshire John Andrew , Ledesma‐Carbayo Maria J. , McVeigh Elliot R.
Published: November 2010

Imaging the left ventricular mechanical and hemodynamic response to the stress of exercise may offer early prognosis in select patients with cardiac disease. Here, we demonstrate the feasibility of obtaining simultaneous measurements of longitudinal strain and transvalvular blood velocity during supine bicycle exercise stress in a wide bore magnetic resonance scanner. Combining information from the two datasets, we observe that although the time to peak strain (33.28 ± 1.86 versus 25.7 ± 2.12 as % of R–R interval) and time to peak mitral inflow velocity (44.37 ± 5.21 versus 35.5 ± 4.19 as % of R–R interval) from R‐wave of the QRS complex occurred earlier during stress, the time from peak strain to peak mitral inflow velocity was not statistically different (16.5 ± 3.23 versus 13.4 ± 3.06). Further, the percentage of longitudinal relaxation at peak mitral inflow velocity was higher during stress (63.5 ± 7.72 versus 84.32 ± 6.24). These results suggest that although diastole is shortened, early diastolic filling efficiency is augmented during exercise stress in normal volunteers in an effort to maintain stroke volume. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Three‐dimensional mapping of the B1 field using an optimized phase‐based method: Application to hyperpolarized 3He in lungs
Authors: Santoro Davide , Rivoire Julien , Meise Florian , Terekhov Maxim , Salhi Zahir , Gast Klaus , Schreiber Laura M.
Published: November 2010

A novel method is presented for the three‐dimensional mapping of the B1‐field of a transmit radio‐frequency MR coil. The method is based on the acquisition of phase images, where the effective flip angle is encoded in the phase of the nonselective hard pulse excitation. The method involves the application of a rectangular composite pulse as excitation in a three‐dimensional gradient recall echo to produce measurable phase angle variation. However, such a pulse may significantly increase the radio‐frequency power deposition in excess of the standard acceptable SAR limits, imposing extremely long TRs (>100 msec), which would result in acquisition times significantly greater than a single breath‐hold. In this study, the phases of the radio‐frequency excitation are modified, resulting in a different pulse sequence scheme. It is shown that the new method increases sensitivity with respect to radio‐frequency inhomogeneities by up to 10 times, and reduces the total duration of the pulse so that three‐dimensional B1 mapping is possible with 3He in lungs within a single breath‐hold. Computer simulations demonstrate the increase in sensitivity. Phantom results with 1H MRI are used for validation. In vivo results are presented with hyperpolarized 3He in human lungs at 1.5T. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Electroluminescent block copolymers containing oxadiazole and thiophene via ATRP
Authors: Yang Qian , Jin Hao , Xu Yiding , Shen Zhihao , Fan Xinghe , Zou Dechun , Zhou Qifeng
Published: November 2010

Block copolymers containing thiophene units in one block and oxadiazole (OXD) units in the other were prepared. Atom transfer radical polymerization method was used to obtain the thiophene‐containing mesogen‐jacketed polymers, and the kinetic study indicated that the polymerization was controllable and the polymers could be used to initiate the polymerization of the OXD‐containing monomers. Photoluminescent spectra indicated that the fluorescence quantum yields of the polymers increased with increasing content of OXD. And, more OXD domains, that is, more interfaces between the hole‐transport parts and electron‐transport parts, resulting in the higher probability of exciplex formation. The electroluminescent devices containing the block copolymer with 64 mol % OXD as the emissive layer had a maximum brightness of 127 cd/m2 and an extremely low onset voltage of 7.7 V, which indicated that the injection and transport of charge carriers were facilitated and the number of charge carriers was sufficiently high in early time after the voltage was turned on. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Regression of prostate tumors upon combination of hormone ablation therapy and celecoxib in vivo
Authors: Abedinpour Parisa , Baron Véronique T. , Welsh John , Borgström Per
Published: November 2010

BACKGROUND

Hormonal ablation is the standard of treatment for advanced androgen‐dependent prostate cancer. Although tumor regression is usually achieved at first, the cancer inevitably evolves toward androgen‐independence, in part because of the development of mechanisms of resistance and in part because at the tissue level androgen withdrawal is not fully attained. Current research efforts are focused on new therapeutic strategies that will increase the effectiveness of androgen withdrawal and delay recurrence. We used a syngeneic pseudo‐orthotropic mouse model of prostate cancer to test the efficacy of combining androgen withdrawal with FDA‐approved COX‐2 inhibitor celecoxib.

METHODS

GFP‐tagged TRAMP‐C2 cells were co‐implanted with prostate tissue in the dorsal chamber model and tumors were allowed to establish and vascularize. Tumor growth and angiogenesis were monitored in real‐time using fluorescent intravital microscopy (IVM). Androgen withdrawal in mice was achieved using surgical castration or chemical hormonal ablation, alone or in combination with celecoxib (15 mg/kg, twice daily).

RESULTS

Celecoxib alone decreased the growth of prostate tumors mostly by inducing mitotic failure, which resulted in increased apoptosis. Surprisingly, celecoxib did not possess significant angiostatic activity. Surgical or chemical castration prevented the growth of prostate tumors and this, on the other hand, was associated with disruption of the tumor vasculature. Finally, androgen withdrawal combined with celecoxib caused tumor regression through decreased angiogenesis and increased mitosis arrest and apoptosis.

CONCLUSION

Celecoxib, a relatively safe COX‐2‐selective anti‐inflammatory drug, significantly increases the efficacy of androgen withdrawal in vivo and warrants further investigation as a complement therapy for advanced prostate cancer. Prostate 71:813–823, 2011. © 2010 Wiley‐Liss, Inc.
Al
3
+
, Ca2+, Mg2+, and Li+ in aqueous solution: Calculated first-shell anharmonic OH vibrations at 300 K
Authors: Pejov Ljupčo , Spångberg Daniel , Hermansson Kersti
Published: November 2010

The anharmonic OH stretching vibrational frequencies, ν(OH), for the first-shell water molecules around the Li+, Ca2+, Mg2+, and Al3+ ions in dilute aqueous solutions have been calculated based on classical molecular dynamics (MD) simulations and quantum-mechanical (QM) calculations. For Li+(aq), Ca2+(aq), Mg2+(aq), and Al3+(aq), our calculated IR frequency shifts, Δν(OH), with respect to the gas-phase water frequency, are about −300, −350, −450, and −750 cm−1, compared to −290, −290, −420, and −830 cm−1 from experimental infrared (IR) studies. The agreement is thus quite good, except for the order between Li+ and Ca2+. Given that the polarizing field from the Ca2+ ion ought to be larger than that from Li+(aq), our calculated result seems reasonable. Also the absolute OH frequencies agree well with experiment. The method we used is a sequential four-step procedure: QM(electronic) to make a force field+MD simulation+QM(electronic) for point-charge-embedded Mn+ (H2O)xfirst shell (H2O)ysecond shell (H2O)zthird shell clusters+QM(vibrational) to yield the OH spectrum. The many-body Ca2+-water force-field presented in this paper is new. IR intensity-weighting of the density-of-states frequency distributions was carried out by means of the squared dipole moment derivatives.
Thermal conductivity measurement of thin films by a dc method
Authors: Yang Junyou , Zhang Jiansheng , Zhang Hui , Zhu Yunfeng
Published: November 2010

A dc method, which needs no complex numerical calculation and expensive hardware configuration, was developed to measure the cross-plane thermal conductivity of thin films in this paper. Two parallel metallic heaters, which were deposited on different parts of the sample, serve simultaneously as the heaters and temperature sensors during the measurement. A direct current was flowed through the same two metallic strips to heat the thin-film sample. The heating power and the heater’s temperature were obtained by a data acquisition device, and the thermal conductivity of thin film was calculated. To verify the validity of the dc method, several SiO2 films with different thicknesses were deposited on Si wafers, respectively, and their thermal conductivities were measured by both the dc method and 3ω method. The results of two methods are in good agreement within an acceptable error, and they are also inconsistent with some of previously published data.
Probing of interfacial charging and discharging in double-layer devices with a polyimide blocking layer by time-resolved optical second harmonic generation
Authors: Zhang Le , Taguchi Dai , Li Jun , Manaka Takaaki , Iwamoto Mitsumasa
Published: November 2010

By using time-resolved electric field induced second harmonic generation, we directly probed interfacial charging and discharging in double-layer devices with an indium tin oxide (ITO)/polyimide(PI)/N,N′-di-[(1-naphthyl)-N,N′-diphenyl]-(1,1′-biphenyl)-4,4′-diamine (α-NPD) (or pentacene)/Au structure, where PI serves as a blocking layer. The results showed that carriers injected from Au electrodes were responsible for interfacial charging and discharging, but different carrier behaviors were observed for pentacene and α-NPD devices, which implies that two devices have the different electrical properties. By analyzing the devices as a system of a Maxwell–Wagner effect element, we proposed a model that accounted for the difference in the charging and discharging processes in terms of carrier behavior.
Morphological classification of low viscosity drop bag breakup in a continuous air jet stream
Authors: Zhao Hui , Liu Hai-Feng , Li Wei-Feng , Xu Jian-Liang
Published: November 2010

To investigate the effect of Rayleigh–Taylor wave number in the region of maximum cross stream dimension (NRT) on drop breakup morphology, the breakup properties of accelerating low viscosity liquid drops (water and ethanol drops, diameter=1.2–6.6 mm, Weber number=10–80) were investigated using high-speed digital photography. The results of morphological analysis show a good correlation of the observed breakup type with NRT; bag breakup occurred when NRT was 1/3−1, bag-stamen breakup at 1–2, and dual-bag breakup at 2–3. The number of nodes in bag breakup, bag-stamen breakup, and dual-bag breakup all increased with Weber number. The experimental results are consistent with the model estimates and in good agreement with those reported in the literature.
Synchronization of an ensemble of oscillators regulated by their spatial movement
Authors: Sarkar Sumantra , Parmananda P.
Published: November 2010

Synchronization for a collection of oscillators residing in a finite two dimensional plane is explored. The coupling between any two oscillators in this array is unidirectional, viz., master-slave configuration. Initially the oscillators are distributed randomly in space and their autonomous time-periods follow a Gaussian distribution. The duty cycles of these oscillators, which work under an on-off scenario, are normally distributed as well. It is realized that random hopping of oscillators is a necessary condition for observing global synchronization in this ensemble of oscillators. Global synchronization in the context of the present work is defined as the state in which all the oscillators are rendered identical. Furthermore, there exists an optimal amplitude of random hopping for which the attainment of this global synchronization is the fastest. The present work is deemed to be of relevance to the synchronization phenomena exhibited by pulse coupled oscillators such as a collection of fireflies.
Band structure of phononic crystals with general damping
Authors: Hussein Mahmoud I. , Frazier Michael J.
Published: November 2010

In this paper, we present theoretical formalisms for the study of wave dispersion in damped elastic periodic materials. We adopt the well known structural dynamics techniques of modal analysis and state-space transformation and formulate them for the Bloch wave propagation problem. First, we consider a one-dimensional lumped parameter model of a phononic crystal consisting of two masses in the unit cell whereby the masses are connected by springs and dashpot viscous dampers. We then extend our analysis to the study of a two-dimensional phononic crystal, modeled as a dissipative elastic continuum, and consisting of a periodic arrangement of square inclusions distributed in a matrix base material. For our damping model, we consider both proportional damping and general damping. Our results demonstrate the effects of damping on the frequency band structure for various types and levels of damping. In particular, we reveal two intriguing phenomena: branch overtaking and branch cut-off. The former may result in an abrupt drop in the relative band gap size, and the latter implies an opening of full or partial wavenumber (wave vector) band gaps. Following our frequency band structure analysis, we illustrate the concept of a damping ratio band structure.
Benchmarks of electronically excited states: Basis set effects on CASPT2 results
Authors: Silva-Junior Mario R. , Schreiber Marko , Sauer Stephan P. A. , Thiel Walter
Published: November 2010

Vertical excitation energies and one-electron properties are computed for the valence excited states of 28 medium-sized organic benchmark molecules using multistate multiconfigurational second-order perturbation theory (MS-CASPT2) and the augmented correlation-consistent aug-cc-pVTZ basis set. They are compared with previously reported MS-CASPT2 results obtained with the smaller TZVP basis. The basis set extension from TZVP to aug-cc-pVTZ causes rather minor and systematic shifts in the vertical excitation energies that are normally slightly reduced (on average by 0.11 eV for the singlets and by 0.09 eV for the triplets), whereas the changes in the calculated oscillator strengths and dipole moments are somewhat more pronounced on a relative scale. These basis set effects at the MS-CASPT2 level are qualitatively and quantitatively similar to those found at the coupled cluster level for the same set of benchmark molecules. The previously proposed theoretical best estimates (TBE-1) for the vertical excitation energies for 104 singlet and 63 triplet excited states of the benchmark molecules are upgraded by replacing TZVP with aug-cc-pVTZ data that yields a new reference set (TBE-2). Statistical evaluations of the performance of density functional theory (DFT) and semiempirical methods lead to the same ranking and very similar quantitative results for TBE-1 and TBE-2, with slightly better performance measures with respect to TBE-2. DFT/MRCI is most accurate among the investigated DFT-based approaches, while the OMx methods with orthogonalization corrections perform best at the semiempirical level.
Submillimeter-wave and far-infrared spectroscopy of high-J transitions of the ground and ν2=1 states of ammonia
Authors: Yu Shanshan , Pearson John C. , Drouin Brian J. , Sung Keeyoon , Pirali Olivier , Vervloet Michel , Martin-Drumel Marie-Aline , Endres Christian P. , Shiraishi Tetsuro , Kobayashi Kaori , Matsushima Fusakazu
Published: November 2010

Complete and reliable knowledge of the ammonia spectrum is needed to enable the analysis and interpretation of astrophysical and planetary observations. Ammonia has been observed in the interstellar medium up to J=18 and more highly excited transitions are expected to appear in hot exoplanets and brown dwarfs. As a result, there is considerable interest in observing and assigning the high J (rovibrational) spectrum. In this work, numerous spectroscopic techniques were employed to study its high J transitions in the ground and ν2=1 states. Measurements were carried out using a frequency multiplied submillimeter spectrometer at Jet Propulsion Laboratory (JPL), a tunable far-infrared spectrometer at University of Toyama, and a high-resolution Bruker IFS 125 Fourier transform spectrometer (FTS) at Synchrotron SOLEIL. Highly excited ammonia was created with a radiofrequency discharge and a dc discharge, which allowed assignments of transitions with J up to 35. One hundred and seventy seven ground state and ν2=1 inversion transitions were observed with microwave accuracy in the 0.3–4.7 THz region. Of these, 125 were observed for the first time, including 26 ΔK=3 transitions. Over 2000 far-infrared transitions were assigned to the ground state and ν2=1 inversion bands as well as the ν2 fundamental band. Of these, 1912 were assigned using the FTS data for the first time, including 222 ΔK=3 transitions. The accuracy of these measurements has been estimated to be 0.0003–0.0006 cm−1. A reduced root mean square error of 0.9 was obtained for a global fit of the ground and ν2=1 states, which includes the lines assigned in this work and all previously available microwave, terahertz, far-infrared, and mid-infrared data. The new measurements and predictions reported here will support the analyses of astronomical observations by high-resolution spectroscopy telescopes such as Herschel, SOFIA, and ALMA. The comprehensive experimental rovibrational energy levels reported here will permit further refinement of the potential energy surface to improve ammonia ab initio calculations and facilitate assignment of new high-resolution spectra of hot ammonia.
Ejection of spalled layers from laser shock-loaded metals
Authors: Lescoute E. , De Rességuier T. , Chevalier J.-M. , Loison D. , Cuq-Lelandais J.-P. , Boustie M. , Breil J. , Maire P.-H. , Schurtz G.
Published: November 2010

Dynamic fragmentation of shock-loaded metals is an issue of considerable importance for both basic science and a variety of technological applications, such as inertial confinement fusion, which involves high energy laser irradiation of thin metallic shells. In this context, we present an experimental and numerical study of debris ejection in laser shock-loaded metallic targets (aluminum, gold, and iron) where fragmentation is mainly governed by spall fracture occurring upon tensile loading due to wave interactions inside the sample. Experimental results consist of time-resolved velocity measurements, transverse optical shadowgraphy of ejected debris, and postshock observations of targets and fragments recovered within a transparent gel of low density. They are compared to numerical computations performed with a hydrodynamic code. A correct overall consistency is obtained.
Double tearing mode induced by parallel electron viscosity in tokamak plasmas
Authors: He Zhixiong , Dong J. Q. , Long Y. X. , Mou Z. Z. , Gao Zhe , He H. D. , Liu F. , Shen Y.
Published: November 2010

The linear behaviors of the double tearing mode (DTM) mediated by parallel electron viscosity in cylindrical plasmas with reversed magnetic shear and thus two resonant rational flux surfaces is numerically investigated. The distance between the two surfaces is found to play an important role for modes with poloidal mode number m>1. Two modes, one of which is centered at the inner rational surface and the other is located between the two surfaces, are simultaneously unstable and the growth rates show the standard single tearing mode (STM) scaling as γ∝R−1/3 when the distance is large (here, the Reynolds number R≡τυ/τh, τυ, and τh are, respectively, the viscosity penetration time of the magnetic field and the Alfvén time for a plasma sheet of width a). The latter is unstable only and the growth rate transits to the standard DTM scaling as γ∝R−1/5 for low-m (e.g., m<4) modes and keeps the STM scaling γ∝R−1/3 for high-m (e.g., m∼10) modes, which are found dominant, when the distance is decreased. In contrast, two unstable modes extending from plasma center to the two rational surfaces, respectively, coexist and the growth rates always show the scaling of γ∝R−1/5, independent of the distance, when the poloidal mode number m=1. The DTMs mediated by electron viscosity are enhanced by plasma resistivity of the range where the growth rate of the mode induced by the latter alone is comparable with that mediated by the former alone and vice versa. Otherwise, the growth rate of the mode is equal to the higher of the modes mediated by resistivity or electron viscosity alone when both of them are taken into account.
Light absorption and electrical transport in Si:O alloys for photovoltaics
Authors: Mirabella S. , Di Martino G. , Crupi I. , Gibilisco S. , Miritello M. , Lo Savio R. , Di Stefano M. A. , Di Marco S. , Simone F. , Priolo F.
Published: November 2010

Thin films (100–500 nm) of the Si:O alloy have been systematically characterized in the optical absorption and electrical transport behavior, by varying the Si content from 43 up to 100 at. %. Magnetron sputtering or plasma enhanced chemical vapor deposition have been used for the Si:O alloy deposition, followed by annealing up to 1250 °C. Boron implantation (30 keV, 3–30×1014 B/cm2) on selected samples was performed to vary the electrical sheet resistance measured by the four-point collinear probe method. Transmittance and reflectance spectra have been extracted and combined to estimate the absorption spectra and the optical band gap, by means of the Tauc analysis. Raman spectroscopy was also employed to follow the amorphous-crystalline (a-c) transition of the Si domains contained in the Si:O films. The optical absorption and the electrical transport of Si:O films can be continuously and independently modulated by acting on different parameters. The light absorption increases (by one decade) with the Si content in the 43–100 at. % range, determining an optical band gap which can be continuously modulated into the 2.6–1.6 eV range, respectively. The a-c phase transition in Si:O films, causing a significant reduction in the absorption coefficient, occurs at increasing temperatures (from 600 to 1100 °C) as the Si content decreases. The electrical resistivity of Si:O films can be varied among five decades, being essentially dominated by the number of Si grains and by the doping. Si:O alloys with Si content in the 60–90 at. % range (named oxygen rich silicon films), are proved to join an appealing optical gap with a viable conductivity, being a good candidate for increasing the conversion efficiency of thin-film photovoltaic cell.
A nonideal error-field response model for strongly shaped tokamak plasmas
Authors: Fitzpatrick R.
Published: November 2010

A model is developed that describes the error-field response of a toroidally rotating tokamak plasma possessing a strongly shaped poloidal cross-section. The response is made up of nondissipative ideal and dissipative nonideal components. The calculation of the ideal response is greatly simplified by employing a large aspect-ratio, constant pressure plasma equilibrium in which the current is entirely concentrated at the boundary. Moreover, the calculation of the resonant component of the nonideal response is simplified by modeling each resonant surface within the plasma as a toroidally rotating, thin resistive shell that only responds to the appropriate resonant component of the perturbed magnetic field. This approach mimics dissipation due to continuum damping at Alfvén and/or sound wave resonances inside the plasma. The nonresonant component of the nonideal response is neglected. The error-fields that maximize the net toroidal locking torque exerted on the plasma are determined via singular value decomposition of the total response matrix. For a strongly dissipative plasma, the locking torque associated with a general error-field is found to peak at a beta value that lies above the no-wall beta-limit, in accordance with experimental observations.
The influence of microstructure on magnetic properties of nanocrystalline Fe–Pt–Nb–B permanent magnet ribbons
Authors: Randrianantoandro N. , Crisan A. D. , Crisan O. , Marcin J. , Kovac J. , Hanko J. , Grenèche J. M. , Svec P. , Chrobak A. , Skorvanek I.
Published: November 2010

A FePt-based hard-magnetic nanocomposite of exchange spring type was prepared by isothermal annealing of melt-spun Fe52Pt28Nb2B18 (atomic percent) ribbons. The relationship between microstructure and magnetic properties was investigated by qualitative and quantitative structural analysis based on the x-ray diffraction, transmission electron microscopy, and F57e Mössbauer spectrometry on one hand and the superconducting quantum interference device magnetometry on the other hand. The microstructure consists of L10-FePt hard-magnetic grains (15–45 nm in diameter) dispersed in a soft magnetic medium composed by A1 FePt, Fe2B, and boron-rich (FeB)PtNb remainder phase. The ribbons annealed at 700 °C for 1 h exhibit promising hard-magnetic properties at room temperature: Mr/Ms=0.69; Hc=820 kA/m and (BH)max=70 kJ/m3. Strong exchange coupling between hard and soft magnetic phases was demonstrated by a smooth demagnetizing curve and positive δM-peak in the Henkel plot. The magnetic properties measured from 5 to 750 K reveals that the hard characteristics remains rather stable up to 550 K, indicating a good prospect for the use of these permanent magnets in a wide temperature range.
Thermal oxidation of polycrystalline tungsten nanowire
Authors: You G. F. , Thong John T. L.
Published: November 2010

The progressive oxidation of polycrystalline tungsten nanowires with diameters in the range of 10–28 nm is studied. The structure and morphology of the tungsten and tungsten oxide nanowires were investigated in detail by transmission electron microscopy. By observing changes in the oxide-shell thickness, a self-limiting oxidation mechanism was found to retard the oxidation rate. Surface reaction and the oxygen diffusion effects were considered in order to understand the influence of stress on the oxidation process.
Electron thermal effect on linear and nonlinear coupled Shukla–Varma and convective cell modes in dust-contaminated magnetoplasma
Authors: Masood W. , Mirza Arshad M.
Published: November 2010

Linear and nonlinear properties of coupled Shukla–Varma (SV) and convective cell modes in the presence of electron thermal effects are studied in a nonuniform magnetoplasma composed of electrons, ions, and extremely massive and negatively charged immobile dust grains. In the linear case, the modified dispersion relation is given and, in the nonlinear case, stationary solutions of the nonlinear equations that govern the dynamics of coupled SV and convective cell modes are obtained. It is found that electrostatic dipolar and vortex street type solutions can appear in such a plasma. The relevance of the present investigation with regard to the Earth’s mesosphere as well as in ionospheric plasmas is also pointed out.
Optomechanics in an ultrahigh-Q two-dimensional photonic crystal cavity
Authors: Safavi-Naeini Amir H. , Alegre Thiago P. Mayer , Winger Martin , Painter Oskar
Published: November 2010

We demonstrate an ultrahigh-Q slotted two-dimensional photonic crystal cavity capable of obtaining strong interaction between the internal light field and the mechanical motion of the slotted structure. The measured optical quality factor is Q=1.2×106 for a cavity with an effective modal volume of Veff=0.04(λ)3. Optical transduction of the thermal motion of the fundamental in-plane mechanical resonance of the structure (νm=151 MHz) is performed, from which a zero-point motion optomechanical coupling rate of g∗/2π=320 kHz is inferred. Dynamical back-action of the optical field on the mechanical motion, resulting in cooling and amplication of the mechanical motion, is also demonstrated.
Surface structuring by ultrashort laser pulses: A review of photoionization models
Authors: Mézel C. , Bourgeade A. , Hallo L.
Published: November 2010

Photoionization models have been introduced and compared in a three-dimensional code utilizing electromagnetic wave propagation in dielectric materials such as fused silica. Ionization rates are initially compared and matched to linear and circular polarizations. Then, they are implemented in the propagation code followed by some hydrodynamic simulations. Results on the structural and optical modifications have been compared with available experimental data. Experimental damage, ablation threshold, and a theoretical damage threshold criteria have been utilized to discriminate between the different models.
Terahertz band gap properties by using metal slits in tapered parallel-plate waveguides
Authors: Lee Eui Su , Ji Young Bin , Jeon Tae-In
Published: November 2010

We present experimental and finite-difference time-domain simulation studies on the properties of Bragg and non-Bragg band gaps; the studies are carried out by using metal slit arrays positioned at the center of the air gaps in tapered parallel-plate waveguides. Two Bragg stop bands, with a dynamic power transmission range of about 26 dB, are observed for an air gap of 29 μm. Two non-Bragg stop bands are observed for an air gap of 94 μm. Using the Ey field distribution and Poynting vectors, we confirm that the Ey field leaking from the slit and the Ey field propagating from another input vanish because they are out of phase. The Bragg and non-Bragg stop bands determined in the simulations show excellent agreement with those observed experimentally.
Competition of the antiferromagnetic superexchange with the ferromagnetic double exchange in dicobalt complexes
Authors: He Lin , Guo Lin
Published: November 2010

Here we report the competition of superexchange and double exchange interactions in the molecule [(NH3)4Co(OH)2Co(NH3)4]4+. Magnetic data reveal a S=3 ground state arising from the competition. The canting angle between the magnetic moments of the Co2+ and Co4+ ions is about 92.5°. The double exchange parameter is estimated to be sevenfold of the superexchange parameter. The result presented here opens a way to introducing of ferromagnetic double exchange interaction to the single molecular magnets via the charge disproportionation between valence-variable transition-metal ions.
THE EQUALIZING EFFECT OF WIVES' EARNINGS ON INEQUALITIES IN EARNINGS AMONG HOUSEHOLDS
Authors: Mastekaasa Arne , Birkelund Gunn Elisabeth
Published: November 2010

Since the 1970s, inequalities in earnings among men have risen in many countries. In the same period, married women's labour force participation has increased. This may affect inequality in household earnings in three ways, related to (a) the degree of inequality in women's earnings, (b) the share of women's earnings of total household earnings, and (c) the correlation of wife's and husband's earnings. Using Annual Norwegian Labour Force Surveys 1974–2004, with added register data on earnings, we find an equalizing effect of wives' earnings over time. Empirical analysis and simulations of hypothetical developments in household earnings inequality show that women's labour supply is the main explanation for these trends.