bluuebunny/crossref_metadata_2025 huggingface dataset:
Collapse of turbulence in stably stratified channel flow: a transient phenomenon
Authors: Donda J. M. M. , van Hooijdonk I. G. S. , Moene A. F. , Jonker H. J. J. , van Heijst G. J. F. , Clercx H. J. H. , van de Wiel B. J. H.
Published: December 2014

The collapse of turbulence in a pressure‐driven, cooled channel flow is studied by using 3D direct numerical simulations (DNS) in combination with theoretical analysis using a local similarity model. Previous studies with DNS reported a definite collapse of turbulence in cases when the normalized surface cooling h/L (with h the channel depth and L the Obukhov length) exceeded a value of 0.5. A recent study by the present authors succeeded in explaining this collapse using the so‐called maximum sustainable heat flux (MSHF) theory. This states that collapse may occur when the ambient momentum of the flow is too weak to transport enough heat downward to compensate for the surface cooling. The MSHF theory predicts that, in pressure‐driven flows, acceleration of the fluid after collapse will eventually cause a regeneration of turbulence, in contrast with the aforementioned DNS results. It also predicts that the flow should be able to survive ‘supercritical’ cooling rates, in cases when sufficient momentum is applied to the initial state. Here, both predictions are confirmed using DNS simulations. It is also shown that in DNS a recovery of turbulence will occur naturally, provided that perturbations of finite amplitude are imposed on the laminarized state and provided that sufficient time for flow acceleration is allowed. As such, we conclude that the collapse of turbulence in this configuration is a temporary, transient phenomenon for which a universal cooling rate does not exist. Finally, in the present work a one‐to‐one comparison between a parametrized, local similarity model and the turbulence‐resolving model (DNS) is made. Although local similarity originates from observations that represent much larger Reynolds numbers than those covered by our DNS simulations, both methods appear to predict very similar mean velocity (and temperature) profiles. This suggests that in‐depth analysis with DNS can be an attractive complementary tool with which to study atmospheric physics, in addition to tools that are able to represent high Reynolds number flows like large‐eddy simulations.
Clear‐sky stable boundary layers with low winds over snow‐covered surfaces. Part 1: WRF model evaluation
Authors: Sterk H. A. M. , Steeneveld G. J. , Vihma T. , Anderson P. S. , Bosveld F. C. , Holtslag A. A. M.
Published: December 2014

In this article, we evaluate the Weather Research and Forecasting (WRF) mesoscale meteorological model for stable conditions in clear skies with low wind speeds. Three contrasting terrains with snow‐covered surfaces are considered, namely Cabauw (Netherlands, snow over grass), Sodankylä (Finland, snow over a needle‐leaf forest) and Halley (Antarctica, snow over an ice shelf). We used the full three‐dimensional (3D) model and the single‐column versions of the WRF model. The single‐column model (SCM) was driven by realistic forcings of the WRF–3D field. Several sets of SCM forcings were tested: A, no advection; B, varying geostrophic wind in time; C, momentum advection in addition to B; D, temperature and moisture advection in addition to C; E, forcing the SCM field to the 3D field above a threshold height.

The WRF–3D model produced good results overall for wind speed, but the near‐surface temperatures and specific humidity were overestimated for Cabauw and Sodankylä and underestimated for Halley. Prescribing advection for momentum, temperature and moisture gave the best results for the WRF–SCM and simulations deviated strongly from reality without advection. Nudging the SCM field to the 3D field above a threshold height led to an unrealistic behaviour of the variables below this height and is not recommended. Detailed prescription of the surface characteristics, e.g. adjusting the snow cover and vegetation fraction, improved the 2 m temperature simulation. For all three sites, the simulated temperature and moisture inversion were underestimated, though this improved when prescribing advection.

Overall, in clear‐sky conditions, the stable boundary layer over snow and ice can be modelled to a good approximation if all processes are taken into account at high resolution and if land surface properties are carefully prescribed.
Performance control for interconnection of identical systems: Application to PLL network design
Authors: Korniienko Anton , Scorletti Gerard , Colinet Eric , Blanco Eric
Published: December 2014

In this paper, the problem of the control law design for interconnected identical systems ensuring the global stability and the global performance properties is under consideration. Inspired by the decentralized control law design methodology using the dissipativity input–output approach, the problem is reduced to the problem of satisfying two conditions: (i) the condition on the interconnection and (ii) the condition on the local subsystem dynamics. Both problems are efficiently solved applying a (quasi‐) convex LMI optimization and standard H∞ synthesis. The proposed design methodology is applied to the control law design of a synchronous PLL network. Copyright © 2014 John Wiley & Sons, Ltd.
Do fecal odors from native and non‐native predators cause a habitat shift among macropods?
Authors: Cox Tarnya E. , Murray Peter J. , Bengsen Andrew J. , Hall Graham P. , Li Xiuhua
Published: December 2014

Predator‐odor‐based repellents have benefits as humane, non‐lethal management tools that may reduce the need for lethal control in some areas. Macropods (such as kangaroos and wallabies) are iconic Australian native marsupials; however, some are considered important rangeland pests, and their presence in the urban and peri‐urban environment often results in conflict. The management of these macropods is a contentious and volatile issue. We evaluated lion (Panthera leo), Sumatran tiger (P. tigris sumatrae), and dingo (Canis lupus dingo) fecal odors as short‐term odor‐based repellents for wild eastern grey kangaroos (Macropus giganteus) and red‐necked wallabies (M. rufogriseus). These odors were used to ‘protect' highly palatable food sources; with any food not consumed (residue) collected and weighed each day. Trials were conducted at Long Grass Nature Reserve in Queensland, Australia from 9–29 January 2009. Both eastern grey kangaroos and red‐necked wallabies relocated a minimum of 100 m away from the food station treated with lion odors on the first day of the trial. As a result of this spatial shift, more food was consumed at the control food stations than at any food station treated with predator odors (regardless of predator). In particular, eastern grey kangaroos never fed from a single predator‐odor food station. An increase in vigilance behaviors was observed for both macropod species, and red‐necked wallabies were more likely to exhibit vigilance behaviors than feeding behaviors at predator odor food stations. There was no difference in food residue between any predator odors and these food stations were only visited on the first day of the study. Use of predator fecal odors may repel macropods from highly palatable food sources, and predator fecal odors also may be useful for macropod relocation. © 2014 The Wildlife Society.
A background subtraction approach based on complex wavelet transforms in EDXRF
Authors: Zhao Fengkui , Wang Aimin
Published: December 2014

Subtracting the background accurately is one of the most important issues in energy‐dispersive X‐ray fluorescence (EDXRF) spectra processing. This paper presents a novel approach to perform background subtraction based on dual‐tree complex wavelet transform. Compared with real wavelet transform, the proposed method has some attractive properties, including a smooth, nonoscillating, and nearly shift‐invariant magnitude with a simple near‐linear phase encoding of signal shifts. Therefore, it outperforms real wavelet transform to decompose background into low‐frequency components. The effectiveness of the proposed approach is demonstrated via two simulated spectra with different kinds of backgrounds and one measured spectrum from an energy‐dispersive X‐ray spectrometer. Both simulated and experimental results prove that the proposed approach can subtract background in EDXRF spectra effectively. Copyright © 2014 John Wiley & Sons, Ltd.
The discovery of Mo(III) in FeMoco: reuniting enzyme and model chemistry
Authors: Bjornsson Ragnar , Neese Frank , Schrock Richard R. , Einsle Oliver , DeBeer Serena
Published: December 2014

Biological nitrogen fixation is enabled by molybdenum-dependent nitrogenase enzymes, which effect the reduction of dinitrogen to ammonia using an Fe7MoS9C active site, referred to as the iron molybdenum cofactor or FeMoco. In this mini-review, we summarize the current understanding of the molecular and electronic structure of FeMoco. The advances in our understanding of the active site structure are placed in context with the parallel evolution of synthetic model studies. The recent discovery of Mo(III) in the FeMoco active site is highlighted with an emphasis placed on the important role that model studies have played in this finding. In addition, the reactivities of synthetic models are discussed in terms of their relevance to the enzymatic system.
Parental Communication and Experiences and Knowledge of Adolescent Siblings of Children with 22q11.2 Deletion Syndrome
Authors: Okashah Rebecca , Schoch Kelly , Hooper Stephen R. , Shashi Vandana , Callanan Nancy
Published: December 2014

22q11.2 deletion syndrome (22q11DS) is the most common microdeletion in humans. There have been few studies assessing the impact of this condition on the family and no previous studies conducted on unaffected siblings of children with 22q11DS. The goal of this study was to determine the frequency, method, and content of information being communicated by parents to unaffected siblings about the condition and to assess unaffected siblings’ knowledge of 22q11DS and perceptions of the impact of the condition on their affected sibling and themselves. Families were recruited from several 22q11DS educational and support organizations and asked to complete a single anonymous online survey. Families were eligible to participate if they had one child with 22q11DS and at least one unaffected child between the ages of 12 and 17. Survey questions were developed based on previous literature and authors’ expertise with individuals with 22q11DS. Responses to quantitative and qualitative questions were analyzed to calculate frequencies and proportions and to extract themes, respectively. A total of 25 families (defined as a unit of at least one parent, one affected child, and at least one unaffected child) participated in the study. Parents shared genetic information less often as compared to behavioral and medical information. Siblings of children with 22q11DS had both positive and negative experiences in having a brother or sister with this condition. Genetic counselors can use the results of this study to develop anticipatory guidance for parents of children with 22q11DS in talking with their unaffected children about the condition.
Over‐expression of bael quinolone synthase in tobacco improves plant vigor under favorable conditions, drought, or salt stress
Authors: Resmi Mohankumar Saraladevi , Vivek Padmanabhan Jayanthi , Soniya Eppurathu Vasudevan
Published: December 2014

Type III polyketide synthases (PKSs) catalyze the biosynthesis of various medicinally important secondary metabolites in plants, but their role in growth and stress response is unclear. Here, we overexpressed quinolone synthase (QNS) from bael in tobacco. QNS‐overexpressing plants showed an overall increase in growth, photosynthetic efficiency and chlorophyll content compared to wild type plants. Second‐generation (T2) transgenic plants grew to maturity, flowered early and set viable seeds under favorable conditions without yield penalty. An increased accumulation of flavonoids, phenols and alkaloids was associated with higher tolerance to drought and salinity stress in transgenic plants. Thus, bael QNS seems to function as a positive regulator of plant growth and stress response, and could be potentially used for engineering plants tolerant to abiotic stress.
Circulating tumor DNA as a non‐invasive substitute to metastasis biopsy for tumor genotyping and personalized medicine in a prospective trial across all tumor types
Authors: Lebofsky Ronald , Decraene Charles , Bernard Virginie , Kamal Maud , Blin Anthony , Leroy Quentin , Rio Frio Thomas , Pierron Gaëlle , Callens Céline , Bieche Ivan , Saliou Adrien , Madic Jordan , Rouleau Etienne , Bidard François-Clément , Lantz Olivier , Stern Marc-Henri , Le Tourneau Christophe , Pierga Jean-Yves
Published: December 2014

Cell‐free tumor DNA (ctDNA) has the potential to enable non‐invasive diagnostic tests for personalized medicine in providing similar molecular information as that derived from invasive tumor biopsies. The histology‐independent phase II SHIVA trial matches patients with targeted therapeutics based on previous screening of multiple somatic mutations using metastatic biopsies. To evaluate the utility of ctDNA in this trial, as an ancillary study we performed de novo detection of somatic mutations using plasma DNA compared to metastasis biopsies in 34 patients covering 18 different tumor types, scanning 46 genes and more than 6800 COSMIC mutations with a multiplexed next‐generation sequencing panel. In 27 patients, 28 of 29 mutations identified in metastasis biopsies (97%) were detected in matched ctDNA. Among these 27 patients, one additional mutation was found in ctDNA only. In the seven other patients, mutation detection from metastasis biopsy failed due to inadequate biopsy material, but was successful in all plasma DNA samples providing three more potential actionable mutations. These results suggest that ctDNA analysis is a potential alternative and/or replacement to analyses using costly, harmful and lengthy tissue biopsies of metastasis, irrespective of cancer type and metastatic site, for multiplexed mutation detection in selecting personalized therapies based on the patient's tumor genetic content.
A note on a Residual Subset of Lipschitz Functions on Metric Spaces
Authors: Cavalletti Fabio
Published: December 2014

Let (X, d) be a quasi-convex, complete and separable metric space with reference probability measure m. We prove that the set of real-valued Lipschitz functions with non-zero pointwise Lipschitz constant m-almost everywhere is residual, and hence dense, in the Banach space of Lipschitz and bounded functions. The result is the metric analogous to a result proved for real-valued Lipschitz maps defined on ℝ2 by Alberti et al.
Unexpected deaths and unplanned re-admissions in infants discharged home after cardiac surgery: a systematic review of potential risk factors
Authors: Tregay Jenifer , Wray Jo , Bull Catherine , Franklin Rodney C. , Daubeney Piers , Barron David J. , Brown Katherine , Knowles Rachel L.
Published: December 2014

Background

Babies with CHDs are a particularly vulnerable population with significant mortality in their 1st year. Although most deaths occur in the hospital within the early postoperative period, around one-fifth of postoperative deaths in the 1st year of life may occur after hospital discharge in infants who have undergone apparently successful cardiac surgery.

Aim

To systematically review the published literature and identify risk factors for adverse outcomes, specifically deaths and unplanned re-admissions, following hospital discharge after infant surgery for life-threatening CHDs.

Methods

A systematic search was conducted in MEDLINE, EMBASE, CINAHL, Cochrane Library, Web of Knowledge, and PsycINFO electronic databases, supplemented by manual searching of conference abstracts.

Results

A total of 15 studies were eligible for inclusion. Almost exclusively, studies were conducted in single US centres and focussed on children with complex single ventricle diagnoses. A wide range of risk factors were evaluated, and those more frequently identified as having a significant association with higher mortality or unplanned re-admission risk were non-Caucasian ethnicity, lower socio-economic status, co-morbid conditions, age at surgery, operative complexity and procedure type, and post-operative feeding difficulties.

Conclusions

Studies investigating risk factors for adverse outcomes post-discharge following diverse congenital heart operations in infants are lacking. Further research is needed to systematically identify higher risk groups, and to develop interventions targeted at supporting the most vulnerable infants within an integrated primary and secondary care pathway.
The Phonology of Westphalian German Glides
Authors: Hall Tracy Alan
Published: December 2014

The present article investigates the patterning of glides in Westphalian German. One question to be addressed is the structure of onglides, for example, theinNase‘nose’ and thein‘village’. I argue that surface onglides are in the nucleus and not in the onset. The proposed representation contrasts with the ones for onglides in related languages, that is, English and Frisian. I show that Westphalian German also possesses a labial approximant [υ]—also known as a consonantal glide—which is distinct from both the onglideand the fricative [v]. I argue that onglides are underlying short vowels, which are parsed as glides by syllabification. The approximant [υ] is argued to be derived from /v/. The proposed analysis is shown to be superior to one in which [υ] derives from /u/, as proposed by Wiese (1996) for New High German.*
The Four Worlds of ‘Welfare Reality’ – Social Risks and Outcomes in Europe
Authors: Ferragina Emanuele , Seeleib-Kaiser Martin , Spreckelsen Thees
Published: December 2014

After three decades of welfare state crisis, change and transformation can we still speak of welfare state regimes when looking at their outcomes? The analysis of outcomes provides a picture of ‘the real worlds of welfare’ and is of considerable importance to understanding political legitimacy across countries. We use aggregate longitudinal data for West European countries in order to map welfare outcomes and cluster countries. The cluster results are also assessed for their sensitivity to the choice of different countries, years or indicators. All European welfare states have a significant capacity for reducing poverty and inequality. However, the degree of this reduction varies considerably, especially when examining different social groups, i.e. unemployed people, children, youths or the elderly. Outcomes cluster countries largely in line with previous institutionalist literature, differentiating between conservative, liberal, Mediterranean and social-democratic regimes. As the main exception, we identify Germany, which can no longer be characterised as the proto-typical conservative welfare state. When analysing old social risks such as unemployment and old age, Europe appears to be characterised by two groups, i.e. one consisting of liberal and Mediterranean countries and a second made up of social-democratic and conservative countries. New social risks such as child and youth poverty, by contrast, replicate very closely the theoretical four-cluster typology. Our sensitivity analyses reveal that our clusters tend to be stable over time. Welfare regimes continue to serve as a useful analytical tool and relate to outcomes experienced by European citizens.
Overviewing the findings: the Technical Panel Review of the Pension Insurance Modeling System
Authors: MITCHELL OLIVIA S.
Published: December 2014

The Pension Benefit Guaranty Corporation's (PBGC) Pension Insurance Modeling System (PIMS) is used to evaluate the financial security and resilience of the national program backstopping private defined benefit plans. The Pension Research Council of the Wharton School at the University of Pennsylvania recently convened a Technical Review Panel of experts to review key inputs, outputs, and model assumptions. Our review was intended to provide a formal evaluation of the technical adequacy of the model by outside experts. The papers herein summarize views of each expert on this project. Key findings are as follows:

•

The PIMS models are an important and valuable tool in modeling the Pension Benefit Guaranty Corporation's liability risk. To the best of our knowledge, there is no other model that can do a comparable job.

•

Nevertheless, some improvements could be integrated in the Agency's approach to modeling. Those deserving highest priority attention, in the experts’ view, include incorporating systematic mortality risk (i.e., treat mortality and longevity as stochastic variables); including new asset classes increasingly found in defined benefit plan portfolios (e.g., commercial real estate, private equity funds, infrastructure, hedge funds, and others); developing a more complex model for the term structure of interest rates; and incorporating an option value approach to pricing the insurance provided.

•

The Agency could also do more to communicate the range of uncertainty and potential for problems associated with the PBGC's financial status. This could include additional information including the conditional value-at-risk, and perhaps an ‘intermediate,’ ‘optimistic’, and ‘pessimistic’ set of projected outcomes, as well as the expected ‘date of exhaustion’ for assets backing pension benefits insured by the PBGC.
Using fluorogenic probes for the investigation of selective biomass degradation by fungi
Authors: Zhang Qian , Peng Xinrui , Grilley Michelle , Takemoto Jon Y. , Chang Cheng-Wei Tom
Published: December 2014

A library of fifteen fluorogenic probes mimicking the linkages in celluloses, hemicelluloses and lignin were screened against crude extracts of white-rot fungi. The fungal enzymes display a high preference for cleaving probes which mimic hemicelluloses. This finding may enable the development of green process for isolating and utilizing hemicelluloses from biomass.
Composite nanoplatelets combining soft-magnetic iron oxide with hard-magnetic barium hexaferrite
Authors: Primc D. , Makovec D.
Published: December 2014

Bi-magnetic, sandwich-type, composite nanoparticles were synthesized by the topotactic growth of a shell of soft-magnetic maghemite (γ-Fe2O3) on platelet core nanoparticles of hard-magnetic barium hexaferrite (BaFe12O19) in an aqueous suspension.
Porous ZnCo2O4nanoparticles derived from a new mixed-metal organic framework for supercapacitors
Authors: Chen Siru , Xue Ming , Li Yanqiang , Pan Ying , Zhu Liangkui , Zhang Daliang , Fang Qianrong , Qiu Shilun
Published: December 2014

ZnCo2O4nanoparticles were synthesized by thermal annealing of a new mixed-metal MOF and show high capacitance for electrochemical capacitors.
Two new members of the niobium-substituted polytungstophosphate family based on hexalacunary [H2P2W12O48]12−building blocks
Authors: Zhang Dongdi , Zhang Chao , Ma Pengtao , Bassil Bassem S. , Al-Oweini Rami , Kortz Ulrich , Wang Jingping , Niu Jingyang
Published: December 2014

Herein we present two structurally novel nanoscale clusters [{Nb6(O2)4P2W12O57}2]20−(1) and [{P2W12Nb7O63(H2O)2}4{Nb4O4(OH)6}]30−(2) formed by controlling the reaction parameters.
Planar trinuclear complexes with linear arrays of metal ions
Authors: Terashima Shotaro , Newton Graham N. , Shiga Takuya , Oshio Hiroki
Published: December 2014

Using a pyridine–pyrazolate ligand H2L (5,5′-pyridyl-3,3′-bi-1H-pyrazole) with two types of bidentate sites allowed the isolation of two trinuclear complexes, [Cu3(L)2](BF4)2 (1) and [Ni3(L)2(MeOH)4](BF4)2 (2). Both complexes have linear trinuclear structures composed of two L2− ligands and three metal ions in a planar arrangement.
An outstanding second-harmonic generation material BiB2O4F: exploiting the electron-withdrawing ability of fluorine
Authors: Cong Rihong , Wang Ying , Kang Lei , Zhou Zhengyang , Lin Zheshuai , Yang Tao
Published: December 2014

The fluorine atoms in BiB2O4F withdraw the non-bonding electrons of Bi3+and thus strongly increase the SHG efficiency.
Cationic Pd(ii)-catalyzed cyclization of N-tosyl-aniline tethered alkynyl ketones initiated by hydropalladation of alkynes: a facile way to 1,2-dihydro or 1,2,3,4-tetrahydroquinoline derivatives
Authors: Shen Kun , Han Xiuling , Xia Guoqin , Lu Xiyan
Published: December 2014

A cationic Pd(ii)-catalyzed intramolecular alkyne-carbonyl reductive coupling reaction of N-tosyl-aniline tethered alkynyl ketones under transfer hydrogenation conditions to give hydroquinolines is developed.
Graphene film-functionalized germanium as a chemically stable, electrically conductive, and biologically active substrate
Authors: Li Jinhua , Wang Gang , Zhang Wenjie , Jin Guodong , Zhang Miao , Jiang Xinquan , Di Zengfeng , Liu Xuanyong , Wang Xi
Published: December 2014

Depositing large-area graphene film by CVD in situ on a Ge semiconductor improves its corrosion resistance, electrical conductivity and biological activity.
Controllable fabrication of nickel nanoparticle chains based on electrochemical corrosion
Authors: Xu Shao Hui , Fei Guang Tao , Ouyang Hao Miao , Zhang Yao , Huo Peng Cheng , De Zhang Li
Published: December 2014

Ni nanoparticle chains are obtained by corroding Cu segments of Ni/Cu nanowires in alkali solution based on electrochemical corrosion.
Lanczos-driven coupled–cluster damped linear response theory for molecules in polarizable environments
Authors: List Nanna Holmgaard , Coriani Sonia , Kongsted Jacob , Christiansen Ove
Published: December 2014

We present an extension of a previously reported implementation of a Lanczos-driven coupled–cluster (CC) damped linear response approach to molecules in condensed phases, where the effects of a surrounding environment are incorporated by means of the polarizable embedding formalism. We are specifically motivated by a twofold aim: (i) computation of core excitations in realistic surroundings and (ii) examination of the effect of the differential response of the environment upon excitation solely related to the CC multipliers (herein denoted the J matrix) in computations of excitation energies and transition moments of polarizable-embedded molecules. Numerical calculations demonstrate that the differential polarization of the environment due to the first-order CC multipliers provides only minor contributions to the solvatochromic shift for all transitions considered. We thus complement previous works by confirming numerically the validity of the routinely invoked neglect of the J matrix contribution as well as motivating future use of the approximation that offers a reduction of the dimensionality of the eigenvalue problem. Preliminary applications to K-edge absorption of liquid water and aqueous acrolein are presented and highlight the importance of the environment that gives rise to transition-specific shifts.
Monoxides of small terbium clusters: A density functional theory investigation
Authors: Zhang G. L. , Yuan H. K. , Chen H. , Kuang A. L. , Li Y. , Wang J. Z. , Chen J.
Published: December 2014

To investigate the effect of oxygen atom on the geometrical structures, electronic, and magnetic properties of small terbium clusters, we carried out the first-principles calculations on TbnO (n = 1-14) clusters. The capping of an oxygen atom on one trigonal-facet of Tbn structures is always favored energetically, which can significantly improve the structural stability. The far-infrared vibrational spectroscopies are found to be different from those of corresponding bare clusters, providing a distinct signal to detect the characteristic structures of TbnO clusters. The primary effect of oxygen atom on magnetic properties is to change the magnetic orderings among Tb atoms and to reduce small of local magnetic moments of the O-coordinated Tb atoms, both of which serve as the key reasons for the experimental magnetic evolution of an oscillating behavior. These calculations are consistent with, and help to account for, the experimentally observed magnetic properties of monoxide TbnO clusters [C. N. Van Dijk et al., J. Appl. Phys. 107, 09B526 (2010)].
Momentum conserving Brownian dynamics propagator for complex soft matter fluids
Authors: Padding J. T. , Briels W. J.
Published: December 2014

We present a Galilean invariant, momentum conserving first order Brownian dynamics scheme for coarse-grained simulations of highly frictional soft matter systems. Friction forces are taken to be with respect to moving background material. The motion of the background material is described by locally averaged velocities in the neighborhood of the dissolved coarse coordinates. The velocity variables are updated by a momentum conserving scheme. The properties of the stochastic updates are derived through the Chapman-Kolmogorov and Fokker-Planck equations for the evolution of the probability distribution of coarse-grained position and velocity variables, by requiring the equilibrium distribution to be a stationary solution. We test our new scheme on concentrated star polymer solutions and find that the transverse current and velocity time auto-correlation functions behave as expected from hydrodynamics. In particular, the velocity auto-correlation functions display a long time tail in complete agreement with hydrodynamics.
Accurate coarse-grained models for mixtures of colloids and linear polymers under good-solvent conditions
Authors: D’Adamo Giuseppe , Pelissetto Andrea , Pierleoni Carlo
Published: December 2014

A coarse-graining strategy, previously developed for polymer solutions, is extended here to mixtures of linear polymers and hard-sphere colloids. In this approach, groups of monomers are mapped onto a single pseudoatom (a blob) and the effective blob-blob interactions are obtained by requiring the model to reproduce some large-scale structural properties in the zero-density limit. We show that an accurate parametrization of the polymer-colloid interactions is obtained by simply introducing pair potentials between blobs and colloids. For the coarse-grained (CG) model in which polymers are modelled as four-blob chains (tetramers), the pair potentials are determined by means of the iterative Boltzmann inversion scheme, taking full-monomer (FM) pair correlation functions at zero-density as targets. For a larger number n of blobs, pair potentials are determined by using a simple transferability assumption based on the polymer self-similarity. We validate the model by comparing its predictions with full-monomer results for the interfacial properties of polymer solutions in the presence of a single colloid and for thermodynamic and structural properties in the homogeneous phase at finite polymer and colloid density. The tetramer model is quite accurate for q ≲ 1 (q=Rˆg/Rc, where Rˆg is the zero-density polymer radius of gyration and Rc is the colloid radius) and reasonably good also for q = 2. For q = 2, an accurate coarse-grained description is obtained by using the n = 10 blob model. We also compare our results with those obtained by using single-blob models with state-dependent potentials.
Effect of ultraviolet illumination on metal oxide resistive memory
Authors: Retamal José Ramón Durán , Kang Chen-Fang , Ho Chih-Hsiang , Ke Jr-Jian , Chang Wen-Yuan , He Jr-Hau
Published: December 2014

We investigate the photoelectrical and resistive switching properties of Pt/ZnO/Pt capacitor operated in unipolar mode under ultraviolet (UV) illumination. The oxygen photodesorption under UV illumination explains the photoconduction observed in initial and high resistance states. Meanwhile, oxygen readsorption at surface-related defects justifies the different photoresponses dynamics in both states. Finally, UV illumination significantly reduces the variations of resistance in high resistance state, set voltage and reset voltage by 58%, 33%, and 25%, respectively, stabilizing Pt/ZnO/Pt capacitor. Our findings in improved switching uniformity via UV light give physical insight into designing resistive memory devices.
Composite thermochemistry of gas phase U(VI)-containing molecules
Authors: Bross David H. , Peterson Kirk A.
Published: December 2014

Reaction energies have been calculated for a series of reactions involving UF6, UO3, UO2(OH)2, and UO2F2 using coupled cluster singles and doubles with perturbative triples, CCSD(T), with a series of correlation consistent basis sets, including newly developed pseudopotential (PP)- and all-electron (AE) Douglas-Kroll-Hess-based sets for the U atom. The energies were calculated using a Feller-Peterson-Dixon composite approach in which CCSD(T) complete basis set (CBS) limits were combined with a series of additive contributions for spin-orbit coupling, outer-core correlation, and quantum electrodynamics effects. The calculated reaction enthalpies (both PP and AE) were combined with the accurately known heat of formation of UF6 to determine the enthalpies of formation of UO3, UO2(OH)2, and UO2F2. The contribution to the reaction enthalpies due to correlation of the 5s5p5d electrons of U was observed to be very slowly convergent with basis set and at the CBS limit their impact on the final enthalpies was on the order of 1 kcal/mol or less. For these closed shell molecules, spin-orbit effects contributed about 1 kcal/mol to the final enthalpies. Interestingly, the PP and AE approaches yielded quite different spin-orbit contributions (similar magnitude but opposite in sign), but the total scalar plus spin-orbit results from the two approaches agreed to within ∼1 kcal/mol of each other. The final composite heat of formation for UO2F2 was in excellent agreement with experiment, while the two results obtained for UO3 were just outside the ±2.4 kcal/mol error bars of the currently recommended experimental value. An improved enthalpy of formation (298 K) for UO2(OH)2 is predicted from this work to be −288.7 ± 3 kcal/mol, compared to the currently accepted experimental value of −292.7 ± 6 kcal/mol.
Ferromagnetic resonance of a magnetic dimer with dipolar coupling
Authors: Franco A. F. , Déjardin J. L. , Kachkachi H.
Published: December 2014

We develop a general formalism for analyzing the ferromagnetic resonance characteristics of a magnetic dimer consisting of two magnetic elements (in a horizontal or vertical configuration) coupled by dipolar interaction, taking account of their finite-size and aspect ratio. We study the effect on the resonance frequency and resonance field of the applied magnetic field (in amplitude and direction), the inter-element coupling, and the (uniaxial) anisotropy in various configurations. We obtain analytical expressions for the resonance frequency in various regimes of the interlayer coupling. We (numerically) investigate the behavior of the resonance field in the corresponding regimes. The critical value of the applied magnetic field at which the resonance frequency vanishes may be an increasing or a decreasing function of the dimer's coupling, depending on the anisotropy configuration. It is also a function of the nanomagnets aspect ratio in the case of in-plane anisotropy. This and several other results of this work, when compared with experiments using the standard ferromagnetic resonance with fixed frequency, or the network analyzer with varying frequency and applied magnetic field, provide a useful means for characterizing the effective anisotropy and coupling within systems of stacked or assembled nanomagnets. Comparing with the experimental data for the frequency splitting of coupled FeV nano disks, we find that our theory provides the same order of magnitude for the dipolar coupling.
On the damping of right hand circularly polarized waves in spin quantum plasmas
Authors: Iqbal Z. , Hussain A. , Murtaza G. , Ali M.
Published: December 2014

General dispersion relation for the right hand circularly polarized waves has been derived using non-relativistic spin quantum kinetic theory. Employing the derived dispersion relation, temporal and spatial damping of the right hand circularly polarized waves are studied for both the degenerate and non-degenerate plasma regimes for two different frequency domains: (i) k∥v≫(ω+ωce),(ω+ωcg) and (ii) k∥v≪(ω+ωce),(ω+ωcg). Comparison of the cold and hot plasma regimes shows that the right hand circularly polarized wave with spin-effects exists for larger k-values as compared to the spinless case, before it damps completely. It is also found that the spin-effects can significantly influence the phase and group velocities of the whistler waves in both the degenerate and non-degenerate regimes. The results obtained are also analyzed graphically for some laboratory parameters to demonstrate the physical significance of the present work.
A three-dimensional metal–organic framework for selective sensing of nitroaromatic compounds
Authors: Tian Dan , Chen Rong-Ying , Xu Jian , Li Yun-Wu , Bu Xian-He
Published: December 2014

A 3D metal–organic framework [NH2(CH3)2][Cd6(L)4(DMF)6(HCOO)](DMF = N,N-dimethylformamide) (1) has been synthesized using a tripodal ligand H3L (2,4,6-tris[1-(3-carboxylphenoxy)ylmethyl]mesitylene). The obtained complex exhibits a 3D framework containing hexanuclear {Cd6} building units formed by two trinuclear {Cd3} clusters that are connected via HCOO− anions. For complex 1, the participation of the fluorescent ligand H3L not only gives rise to a strong photoluminescence emission as expected, but more interestingly, that ligand originated characteristic band could be quenched selectively by nitrobenzene with a low detection limit, showing its potential as a highly sensitive and selective sensor for nitrobenzene. Based on an electron transfer quenching mechanism, the fluorescence sensing ability of 1 is also applicable for other electron-deficient nitroaromatic compounds with high selectivity and sensitivity, i.e., 1,4-dinitrobenzene, 1,3-dinitrobenzene, 2,4-dinitrotoluene, and 4-nitrotoluene, suggesting 1 a promising fluorescence sensor for detecting and recognizing the same kind of chemicals.
Phenomenological model of photoluminescence degradation and photoinduced defect formation in silicon nanocrystal ensembles under singlet oxygen generation
Authors: Gongalsky Maxim B. , Timoshenko Victor Yu.
Published: December 2014

We propose a phenomenological model to explain photoluminescence degradation of silicon nanocrystals under singlet oxygen generation in gaseous and liquid systems. The model considers coupled rate equations, which take into account the exciton radiative recombination in silicon nanocrystals, photosensitization of singlet oxygen generation, defect formation on the surface of silicon nanocrystals as well as quenching processes for both excitons and singlet oxygen molecules. The model describes well the experimentally observed power law dependences of the photoluminescence intensity, singlet oxygen concentration, and lifetime versus photoexcitation time. The defect concentration in silicon nanocrystals increases by power law with a fractional exponent, which depends on the singlet oxygen concentration and ambient conditions. The obtained results are discussed in a view of optimization of the photosensitized singlet oxygen generation for biomedical applications.
Graphene-based transparent flexible heat conductor for thermally tuning nanophotonic integrated devices
Authors: Yu Longhai , Dai Daoxin , He Sailing
Published: December 2014

Graphene, a well-known two-dimensional sheet, has attracted strong interest for both fundamental studies and applications. Due to its high intrinsic thermal conductivity, graphene has many potential applications in thermal management, such as in heat spreaders and flexible heaters. In this paper, a graphene-based transparent flexible heat conductor for nanophotonic integrated devices is demonstrated. The graphene heat conductor is designed to deliver heat from a non-local traditional metal heater to nanophotonic integrated devices for realizing efficient thermal tuning. With the present graphene heat conductor, a thermally tuning silicon Mach-Zehnder interferometer and micro-disk have been realized with good performance in terms of heating efficiency and temporal response. This indicates that the present graphene-based transparent flexible heat conductor provides an efficient and beneficial heating method for thermally tuning nanophotonic integrated devices.
Tracking of large-scale structures in turbulent channel with direct numerical simulation of low Prandtl number passive scalar
Authors: Tiselj Iztok
Published: December 2014

Channel flow DNS (Direct Numerical Simulation) at friction Reynolds number 180 and with passive scalars of Prandtl numbers 1 and 0.01 was performed in various computational domains. The “normal” size domain was ∼2300 wall units long and ∼750 wall units wide; size taken from the similar DNS of Moser et al. The “large” computational domain, which is supposed to be sufficient to describe the largest structures of the turbulent flows was 3 times longer and 3 times wider than the “normal” domain. The “very large” domain was 6 times longer and 6 times wider than the “normal” domain. All simulations were performed with the same spatial and temporal resolution. Comparison of the standard and large computational domains shows the velocity field statistics (mean velocity, root-mean-square (RMS) fluctuations, and turbulent Reynolds stresses) that are within 1%-2%. Similar agreement is observed for Pr = 1 temperature fields and can be observed also for the mean temperature profiles at Pr = 0.01. These differences can be attributed to the statistical uncertainties of the DNS. However, second-order moments, i.e., RMS temperature fluctuations of standard and large computational domains at Pr = 0.01 show significant differences of up to 20%. Stronger temperature fluctuations in the “large” and “very large” domains confirm the existence of the large-scale structures. Their influence is more or less invisible in the main velocity field statistics or in the statistics of the temperature fields at Prandtl numbers around 1. However, these structures play visible role in the temperature fluctuations at low Prandtl number, where high temperature diffusivity effectively smears the small-scale structures in the thermal field and enhances the relative contribution of large-scales. These large thermal structures represent some kind of an echo of the large scale velocity structures: the highest temperature-velocity correlations are not observed between the instantaneous temperatures and instantaneous streamwise velocities, but between the instantaneous temperatures and velocities averaged over certain time interval.
Remote sensing and reconstruction of thermal transients in a one-dimensional solid rod using thermoelastic waves
Authors: Feeley Matthew , Sen Mihir , Semperlotti Fabio
Published: December 2014

We investigate the use of thermoelastic waves in solids to remotely sense and reconstruct dynamic temperature fields beyond the capabilities of currently available thermal sensors. We propose a methodology for the reconstruction of amplitude and location of thermal transients based on temperature-induced acoustic generation by exploiting the coupled thermoelastic behavior of solids. Temporal and spatial gradients in temperatures at surface or interior points in a solid induce acoustic waves that can be detected and used for the identification and reconstruction of the thermal load. The methodology is developed and numerically investigated by using a one-dimensional solid rod as an example. Results show that even step-like thermal transients can be accurately reconstructed based on the measured acoustic response.
Analysis of electron capture process in charge pumping sequence using time domain measurements
Authors: Hori Masahiro , Watanabe Tokinobu , Tsuchiya Toshiaki , Ono Yukinori
Published: December 2014

A method for analyzing the electron capture process in the charge pumping (CP) sequence is proposed and demonstrated. The method monitors the electron current in the CP sequence in time domain. This time-domain measurements enable us to directly access the process of the electron capture to the interface defects, which are obscured in the conventional CP method. Using the time-domain measurements, the rise time dependence of the capture process is systematically investigated. We formulate the capture process based on the rate equation and derive an analytic form of the current due to the electron capture to the defects. Based on the formula, the experimental data are analyzed and the capture cross section is obtained. In addition, the time-domain data unveil that the electron capture process completes before the electron channel opens, or below the threshold voltage in a low frequency range of the pulse.
Permeabilization of yeast Saccharomyces cerevisiae cell walls using nanosecond high power electrical pulses
Authors: Stirke A. , Zimkus A. , Balevicius S. , Stankevic V. , Ramanaviciene A. , Ramanavicius A. , Zurauskiene N.
Published: December 2014

The electrical field-induced changes of the yeast Saccharomyces cerevisiae cells permeabilization to tetraphenylphosphonium (TPP+) ions were studied using square-shaped, nanosecond duration high power electrical pulses. It was obtained that pulses having durations ranging from 10 ns to 60 ns, and generating electric field strengths up to 190 kV/cm significantly (up to 65 times) increase the absorption rate of TPP+ ions without any detectible influence on the yeast cell viability. The modelling of the TPP+ absorption process using a second order rate equation demonstrates that depending on the duration of the pulses, yeast cell clusters of different sizes are homogeniously permeabilized. It was concluded, that nanosecond pulse-induced permeabilization can be applied to increase the operational speed of whole cell biosensors.
Atomic layer epitaxy of Ruddlesden-Popper SrO(SrTiO3)n films by means of metalorganic aerosol deposition
Authors: Jungbauer M. , Hühn S. , Egoavil R. , Tan H. , Verbeeck J. , Van Tendeloo G. , Moshnyaga V.
Published: December 2014

We report an atomic layer epitaxial growth of Ruddlesden-Popper (RP) thin films of SrO(SrTiO3)n (n = ∞, 2, 3, 4) by means of metalorganic aerosol deposition (MAD). The films are grown on SrTiO3(001) substrates by means of a sequential deposition of Sr-O/Ti-O2 atomic monolayers, monitored in-situ by optical ellipsometry. X-ray diffraction and transmission electron microscopy (TEM) reveal the RP structure with n = 2–4 in accordance with the growth recipe. RP defects, observed by TEM in a good correlation with the in-situ ellipsometry, mainly result from the excess of SrO. Being maximal at the film/substrate interface, the SrO excess rapidly decreases and saturates after 5–6 repetitions of the SrO(SrTiO3)4 block at the level of 2.4%. This identifies the SrTiO3 substrate surface as a source of RP defects under oxidizing conditions within MAD. Advantages and limitations of MAD as a solution-based and vacuum-free chemical deposition route were discussed in comparison with molecular beam epitaxy.
Contribution of ions in radio frequency properties of atmospheric pressure microgaps
Authors: Semnani Abbas , Peroulis Dimitrios
Published: December 2014

In this paper, the contribution of ions in RF permittivity and electrical conductivity of atmospheric pressure micro- and sub-microgaps in both pre-breakdown and post-breakdown regimes is investigated. It is shown that ions are ignorable in post-breakdown conditions, while their role becomes significant in pre-breakdown mode especially for gaps on the right side of Paschen's curve. Also, it is demonstrated that the contribution of ions in RF properties increases by decreasing the operating frequency in comparison with ion-neutral collision frequency.