bluuebunny/crossref_metadata_2025 huggingface dataset:
Melting of icosahedral nickel clusters under hydrostatic pressure
Authors: Fu Bing , Chen Li , Wang Feifei , Xie Yiqun , Ye Xiang
Published: September 2014

The thermal stabilities and melting behavior of icosahedral nickel clusters under hydrostatic pressure have been studied by constant‐pressure molecular dynamics simulation. The potential energy and Lindemann index are calculated. The overall melting temperature exhibits a strong dependence on pressure. The Lindemann index of solid structure before melting varies slowly and is almost independent of pressure. However, after the clusters melt completely, the Lindemann index at the overall melting point strongly depends on pressure. The overall melting temperature is found to be increasing nonlinearly with increasing pressure, while the volume change during melting decreases linearly with increasing pressure. Under a high pressure and temperature environment, similar angular distributions were found between liquid and solid structures, indicating the existence of a converging local structure. © 2014 Wiley Periodicals, Inc.
A theory of behavioral contrast
Authors: Killeen Peter R.
Published: September 2014

The reinforcers that maintain target instrumental responses also reinforce other responses that compete with them for expression. This competition, and its imbalance at points of transition between different schedules of reinforcement, causes behavioral contrast. The imbalance is caused by differences in the rates at which different responses come under the control of component stimuli. A model for this theory of behavioral contrast is constructed by expanding the coupling coefficient of MPR (Killeen, 1994). The coupling coefficient gives the degree of association of a reinforcer with the target response (as opposed to other competing responses). Competing responses, often identified as interim or adjunctive or superstitious behavior, are intrinsic to reinforcement schedules, especially interval schedules. In addition to that base‐rate of competition, additional competing responses may spill over from the prior component, causing initial contrast; and they may be modulated by conditioned reinforcement or punishment from stimuli associated with subsequent component change, causing terminal contrast. A formalization of these hypotheses employed (a) a hysteresis model of off‐target responses giving rise to initial contrast, and (b) a competing traces model of the suppression or enhancement of ongoing competitive responses by signals of following‐schedule transition. The theory was applied to transient contrast, the following schedule effect, and the component duration effect.
Is Health a Necessity in Sub‐Saharan Africa? An Investigation of Income‐Elasticity of Health Expenditures In Rural Senegal
Authors: Lépine Aurélia
Published: September 2014

Investigating income‐elasticity of health expenditures can provide insights into the extent of public involvement in the health sector and the need for co‐financing schemes. Although this is particularly relevant in vulnerable countries, evidence from sub‐Saharan Africa is lacking. The paper explores the relationship between permanent and current income and health expenditures. First, at the patient level, income‐elasticity of health expenditures during the last medical contact with a qualified health provider is investigated. Second, household‐level estimation of income‐elasticity of household health expenditures is conducted to account for the healthcare use rate. The results suggest that health is a necessity good, which has methodological and policy implications. Copyright © 2014 John Wiley & Sons, Ltd.
Different spatial expressions of c‐Fos in the nucleus of the solitary tract following taste stimulation with sodium, potassium, and ammonium ions in rats
Authors: Kwak Yongho , Han Jeongsoo , Rhyu Mee‐Ra , Nam Taick Sang , Leem Joong Woo , Lee Bae Hwan
Published: September 2014

Cation‐specific epithelial receptors on the tongue have been well demonstrated. However, active regions along the nucleus of the solitary tract (NST) for cations Na+, K+, NH4+ are still unclear, even though the best responses of NST neurons to taste stimuli vary depending on the cell. In the present study, the spatial distribution patterns of cation‐specific active regions in the NST are investigated. The tongues of urethane‐anesthetized Sprague‐Dawley rats (n = 25) were stimulated with artificial saliva (control), 0.5 M NaCl, 1.0 M NaCl, 0.5 M KCl, and 0.3 M NH4Cl. Then, the three‐dimensional positions of c‐Fos‐like‐immunoreactive (cFLI) cells in the NST were generated. The spatial distributions of cFLI cells in the NST were compared among five taste stimulations. cFLI cells were observed throughout the NST, irrespective of the stimulus; however, the intermediate‐medial central regions of the NST had higher numbers of cFLI cells than the other regions in all taste stimulations. Analysis of images revealed that the activated regions in the NST differed significantly depending on the cations. The intermediate‐dorsal‐central region and the caudal‐ventral region were activated by a 0.5 M concentration of sodium, the rostral‐ventral region and the intermediate‐dorsal/ventral region were activated by a 1.0 M concentration of sodium, the intermediate‐dorsal/ventral region was activated by potassium ions, and the rostral‐ventral region and the intermediate‐ventral central region were activated by ammonium ions. These results suggest that the responses of NST cells to cation salt ions are regulated differentially. © 2014 Wiley Periodicals, Inc.
Design of guanidinium ionic liquid based microwave‐assisted extraction for the efficient extraction of Praeruptorin A from Radix peucedani
Authors: Ding Xueqin , Li Li , Wang Yuzhi , Chen Jing , Huang Yanhua , Xu Kaijia
Published: September 2014

A series of novel tetramethylguanidinium ionic liquids and hexaalkylguanidinium ionic liquids have been synthesized based on 1,1,3,3‐tetramethylguanidine. The structures of the ionic liquids were confirmed by 1H NMR spectroscopy and mass spectrometry. A green guanidinium ionic liquid based microwave‐assisted extraction method has been developed with these guanidinium ionic liquids for the effective extraction of Praeruptorin A from Radix peucedani. After extraction, reversed‐phase high‐performance liquid chromatography with UV detection was employed for the analysis of Praeruptorin A. Several significant operating parameters were systematically optimized by single‐factor and L9 (34) orthogonal array experiments. The amount of Praeruptorin A extracted by [1,1,3,3‐tetramethylguanidine]CH2CH(OH)COOH is the highest, reaching 11.05 ± 0.13 mg/g. Guanidinium ionic liquid based microwave‐assisted extraction presents unique advantages in Praeruptorin A extraction compared with guanidinium ionic liquid based maceration extraction, guanidinium ionic liquid based heat reflux extraction and guanidinium ionic liquid based ultrasound‐assisted extraction. The precision, stability, and repeatability of the process were investigated. The mechanisms of guanidinium ionic liquid based microwave‐assisted extraction were researched by scanning electron microscopy and IR spectroscopy. All the results show that guanidinium ionic liquid based microwave‐assisted extraction has a huge potential in the extraction of bioactive compounds from complex samples.
Water‐Based Adhesives with Tailored Hydrophobic Association: Dilution Resistance and Improved Setting Behavior
Authors: Dundua Alexander , Landfester Katharina , Taden Andreas
Published: September 2014

Hydrophobic association and stimuli‐responsiveness is a powerful tool towards water‐based adhesives with strongly improved properties, which is demonstrated based on the example of hydrophobically modified alkali‐soluble latexes (HASE) with modulated association. Their rheological properties are highly tunable due to the hydrophobic domains that act as physical crosslinking sites of adjustable interaction strength. Ethanol, propanol, and butanol are used as water‐soluble model additives with different hydrophobicity in order to specifically target the association sites and impact the viscoelastic properties and stimuli‐responsiveness. The rheological and mechanical property response upon dilution with water can be tailored, and dilution‐resistant or even dilution‐thickening systems are obtained. The investigations are of high importance for water‐based adhesives, as our findings provide insight into general structure–property relationships to improve their setting behavior, especially upon contact with wet substrates.

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Increased SNR efficiency in velocity selective arterial spin labeling using multiple velocity selective saturation modules (mm‐VSASL)
Authors: Guo Jia , Wong Eric C.
Published: September 2014

Purpose

Velocity‐selective arterial spin labeling (VSASL) is theoretically insensitive to transit delay (TD) effects. However, it uses saturation instead of inversion, resulting in compromised signal to noise ratio (SNR). In this study we explore the use of multiple velocity‐selective saturation (VSS) modules in VSASL (mm‐VSASL) to improve SNR.

Methods

Theoretical SNR efficiency improvement and optimized parameters were calculated from simulations for mm‐VSASL. VSASL with two VSS modules (VSASL‐2VSS) was implemented to measure cerebral blood flow in vivo, compared with conventional VSASL (VSASL‐1VSS), pulsed ASL (PASL), and pseudo‐continuous ASL (PCASL). TDs and bolus durations (BDs) were measured to validate the simulations and to examine the TD sensitivity of these preparations.

Results

Compared with VSASL‐1VSS, VSASL‐2VSS achieved a significant improvement of SNR (22.1 ± 1.9%, P = 1.7 × 10−6) in vivo, consistent with a 22.7% improvement predicted from simulations. The SNR was comparable to or higher (in gray matter, P = 4.3 × 10−3) than that using PCASL. VSASL was experimentally verified to have minimal TD effects.

Conclusion

Utilizing multiple VSS modules can improve the SNR efficiency of VSASL. Mm‐VSASL may result in an SNR that is comparable to or even higher than that of PCASL in applications where long postlabeling delays are required. Magn Reson Med 74:694–705, 2015. © 2014 Wiley Periodicals, Inc.
F‐ and Cl‐terminations of (100)‐oriented single crystalline diamond
Authors: Widmann C. J. , Giese C. , Wolfer M. , Kono S. , Nebel C. E.
Published: September 2014

The surface termination of single crystalline diamond with fluorine and chlorine was investigated. The diamond was exposed to SF6 inductively coupled plasma for fluorination and to Cl2 plasma for chlorination. For the fluorine termination, the plasma treatment caused one monolayer of fluorine (measured with two angle photoelectron detection) and no carbonyl fluorides on the diamond surface. Furthermore no graphitization or roughening of the surface was observed. The plasma treatment with chlorine led to rough surfaces.
Capturing the User Mindset – Using the Online Research Community Method in Packaging Research
Authors: Joutsela Markus , Korhonen Virpi
Published: September 2014

The rapid development of Web 2.0 technology has enabled new types of online research methods. The collective intelligence of online communities or ‘crowds’ can be harnessed to contribute actively to bodies of knowledge, work or value by means of crowdsourcing. This paper presents a case study of using a crowd‐based research method, more specifically, an online research community (ORC) for collecting information, user experiences and ideas from a community of packaging users. We will discuss the benefits, challenges and opportunities that the method offers to packaging research. A total of 137 participants were recruited to a closed online platform, with 86 of them as active participants. The discussion topics and tasks were pre‐determined by the researchers, and new topics were introduced daily over a period of 13 days. The discussions were moderated in order to keep them on topic and to propose additional questions when required. The platform suited well for gathering user information, feedback and insights on various packaging designs and development topics. The case study also demonstrated that the ORC method can provide valuable insights on usability, packaging communication, consumer behaviour and user experiences. The research yielded rich data, even on such a complex issue as the relation of packaging to food loss prevention. The method can be employed to collect both quantitative and qualitative data from a crowd. However, answers provided by individual participants may remain less grounded and less rich in detail than those elicited with other qualitative methods, such as interviews or focus groups. Copyright © 2014 John Wiley & Sons, Ltd.
An efficient parallel algorithm for exact multi‐pattern matching
Authors: Zhang Hongli , Xu Dongliang , Tian Zhihong , Fan Yujian
Published: September 2014

This paper presents a parallel algorithm Parallel Extended Bloom Filter (PEBF) for exact multi‐pattern matching based on Bloom filter. To improve the throughput and parallelism of the algorithm, we divided the pattern set into N subsets where the length of patterns is the same, and different subsets would not intersect each other. We construct an EBF for each subset and use N threads to simultaneously process the subsets in parallel. We implement our solution on the graphics processing unit, called G‐PEBF. Experimental results demonstrate that PEBF performs better than the Wu–Manber (WM) algorithm in terms of time and space. And G‐PEBF outperforms the G‐WM (WM algorithm implemented on graphics processing unit). The speedup of G‐PEBF is up to 60 times at peak performance and almost 10 times at worst performance to the PEBF algorithm. Copyright © 2014 John Wiley & Sons, Ltd.
Exploring the Possibilities and Limitations of a Nanomaterials Genome
Authors: Qian Chenxi , Siler Todd , Ozin Geoffrey A.
Published: September 2014

What are we going to do with the cornucopia of nanomaterials appearing in the open and patent literature, every day? Imagine the benefits of an intelligent and convenient means of categorizing, organizing, sifting, sorting, connecting, and utilizing this information in scientifically and technologically innovative ways by building a Nanomaterials Genome founded upon an all‐purpose Periodic Table of Nanomaterials. In this Concept article, inspired by work on the Human Genome project, which began in 1989 together with motivation from the recent emergence of the Materials Genome project initiated in 2011 and the Nanoinformatics Roadmap 2020 instigated in 2010, we envision the development of a Nanomaterials Genome (NMG) database with the most advanced data‐mining tools that leverage inference engines to help connect and interpret patterns of nanomaterials information. It will be equipped with state‐of‐the‐art visualization techniques that rapidly organize and picture, categorize and interrelate the inherited behavior of complex nanomatter from the information programmed in its constituent nanomaterials building blocks. A Nanomaterials Genome Initiative (NMGI) of the type imagined herein has the potential to serve the global nanoscience community with an opportunity to speed up the development continuum of nanomaterials through the innovation process steps of discovery, structure determination and property optimization, functionality elucidation, system design and integration, certification and manufacturing to deployment in technologies that apply these versatile nanomaterials in environmentally responsible ways. The possibilities and limitations of this concept are critically evaluated in this article.
A novel regeneration of iron citrate solution by biooxidation of iron-oxidizing bacteria
Authors: Wang Y J , Li D P , Liu C , Zhan G Q , He X H
Published: September 2014

Liquid phase oxidation process using chelated iron solution is among the most promising techniques for the hydrogen sulfide removal due to its double advantage of waste minimization and resource recovery. Regeneration of chelated iron is a core reaction in this process. Regeneration of chelated iron in acidic solution is very difficult. In this paper, a novel regeneration of iron citrate in acidic solution by biooxidation of iron-oxidizing bacteria was reported firstly. By using such a process, the influence of iron-oxidizing bacteria on the regeneration rate was investigated. The results demonstrated the regeneration rate with the new technology was increased significantly. The process may contribute to the biooxidation of iron-oxidizing bacteria. Application of this novel process increased the regeneration rate under the optimum conditions, suggesting the iron citrate regeneration process may be a feasible and economical method in application.
How the world trade community operates: norms and discourse
Authors: CHO SUNGJOON
Published: September 2014

Based on the new conceptualization of the world trading system as the world trade ‘community’, this Article illuminates its internal operation based on legal discourse. The Article first defines WTO norms aslingua francaof the world trade community that enables various forms of discourse among members of the community. It then introduces three main institutionalized forms of the WTO discourse, namely adjudication, peer review, and consultation/negotiation. These three forms of WTO discourse are mainly responsible for the diurnal operation of the world trade community. The Article also explores the intermodal dynamics among these three forms of WTO discourse and demonstrates that such dynamics might generate both positive and negative consequences.
PICALM modulates autophagy activity and tau accumulation
Authors: Moreau Kevin , Fleming Angeleen , Imarisio Sara , Lopez Ramirez Ana , Mercer Jacob L. , Jimenez-Sanchez Maria , Bento Carla F. , Puri Claudia , Zavodszky Eszter , Siddiqi Farah , Lavau Catherine P. , Betton Maureen , O’Kane Cahir J. , Wechsler Daniel S. , Rubinsztein David C.
Published: September 2014

Genome-wide association studies have identified several loci associated with Alzheimer’s disease (AD), including proteins involved in endocytic trafficking such as PICALM/CALM (phosphatidylinositol binding clathrin assembly protein). It is unclear how these loci may contribute to AD pathology. Here we show that CALM modulates autophagy and alters clearance of tau, a protein which is a known autophagy substrate and which is causatively linked to AD, both in vitro and in vivo. Furthermore, altered CALM expression exacerbates tau-mediated toxicity in zebrafish transgenic models. CALM influences autophagy by regulating the endocytosis of SNAREs, such as VAMP2, VAMP3 and VAMP8, which have diverse effects on different stages of the autophagy pathway, from autophagosome formation to autophagosome degradation. This study suggests that the AD genetic risk factor CALM modulates autophagy, and this may affect disease in a number of ways including modulation of tau turnover.
Plasma nitriding induced growth of Pt-nanowire arrays as high performance electrocatalysts for fuel cells
Authors: Du Shangfeng , Lin Kaijie , Malladi Sairam K. , Lu Yaxiang , Sun Shuhui , Xu Qiang , Steinberger-Wilckens Robert , Dong Hanshan
Published: September 2014

In this work, we demonstrate an innovative approach, combing a novel active screen plasma (ASP) technique with green chemical synthesis, for a direct fabrication of uniform Pt nanowire arrays on large-area supports. The ASP treatment enables in-situ N-doping and surface modification to the support surface, significantly promoting the uniform growth of tiny Pt nuclei which directs the growth of ultrathin single-crystal Pt nanowire (2.5–3 nm in diameter) arrays, forming a three-dimensional (3D) nano-architecture. Pt nanowire arrays in-situ grown on the large-area gas diffusion layer (GDL) (5 cm2) can be directly used as the catalyst electrode in fuel cells. The unique design brings in an extremely thin electrocatalyst layer, facilitating the charge transfer and mass transfer properties, leading to over two times higher power density than the conventional Pt nanoparticle catalyst electrode in real fuel cell environment. Due to the similar challenges faced with other nanostructures and the high availability of ASP for other material surfaces, this work will provide valuable insights and guidance towards the development of other new nano-architectures for various practical applications.
Assembly of a series of d10 coordination polymers of pamoic acid through a mixed-ligand synthetic strategy: syntheses, structures and fluorescence properties
Authors: Cao Tingting , Peng Yanqiang , Liu Ting , Wang Suna , Dou Jianmin , Li Yunwu , Zhou Changhui , Li Dacheng , Bai Junfeng
Published: September 2014

Eight fluorescent coordination compounds were obtained based on H2PA and N-donor ligands through a mixed-ligand synthetic strategy.
Greasy tails switch 1D-coordination [{Zn2(OAc)4(4′-(4-ROC6H4)-4,2′:6′,4′′-tpy)}n] polymers to discrete [Zn2(OAc)4(4′-(4-ROC6H4)-4,2′:6′,4′′-tpy)2] complexes
Authors: Klein Y. Maximilian , Constable Edwin C. , Housecroft Catherine E. , Zampese Jennifer A. , Crochet Aurélien
Published: September 2014

Polymers [{Zn2(OAc)4(4′-(4-ROC6H4)-4,2′:6′,4′′-tpy)}n] with dominant π-stacking interactions are favoured for small RO groups; with long chains, there is a switch to discrete molecules.
Theoretical study of the mechanisms and kinetics of the reactions of hydroperoxy (HO2) radicals with hydroxymethylperoxy (HOCH2O2) and methoxymethylperoxy (CH3OCH2O2) radicals
Authors: Shao Youxiang , Hou Hua , Wang Baoshan
Published: September 2014

The peroxy–peroxy radical reactions show spin, conformation and temperature dependence, forming formic acid and hydroxyl radicals.
Predicting the properties of a new class of host–guest complexes: C60 fullerene and CB[9] cucurbituril
Authors: Fileti Eudes , Colherinhas Guilherme , Malaspina Thaciana
Published: September 2014

DFT, semi-empirical and classical molecular dynamics methods were used to describe the structure and stability of the inclusion complex formed by the fullerene C60 and the cucurbituril CB[9].
Noble-metal-free BODIPY–cobaloxime photocatalysts for visible-light-driven hydrogen production
Authors: Luo Geng-Geng , Fang Kai , Wu Ji-Huai , Dai Jing-Cao , Zhao Qing-Hua
Published: September 2014

Four BODIPY–cobaloxime systemsCo-Bn(n= 1–4) were studied as single-component homogeneous photocatalytic systems for H2generation in aqueous media.
Energy transfer in lanthanide upconversion studies for extended optical applications
Authors: Dong Hao , Sun Ling-Dong , Yan Chun-Hua
Published: September 2014

In this review, the various energy transfer pathways involved in lanthanide-related upconversion emissions are comprehensively discussed.
High three-way catalytic activity of rhodium particles on a Y-stabilized La-containing ZrO2 support: the effect of Y on the enhanced reducibility of rhodium and self-regeneration
Authors: Kawabata Hisaya , Koda Yuki , Sumida Hirosuke , Shigetsu Masahiko , Takami Akihide , Inumaru Kei
Published: September 2014

A novel, highly active three-way catalyst, rhodium supported on Y- and La-added zirconia (Rh/Zr–Y–La–O), was found in this study.
An alternative method for chronometric determinations involving curium
Authors: Kurosaki H. , Cadieux J. R. , Clark S. B.
Published: September 2014

A method for quantifying ratios of isotopes of plutonium (Pu), americium (Am), and curium (Cm) using inductively coupled plasma mass spectrometry (ICP-MS) is described that does not require radiochemical separations or a chemical yield monitor.
Electrochemical modulation of plasma fibronectin surface conformation enables filament formation and control of endothelial cell–surface interactions
Authors: Dargahi Mahdi , Nelea Valentin , Mousa Aisha , Omanovic Sasha , Kaartinen Mari T.
Published: September 2014

Electrochemical modulation of a gold surface charge induces conformational changes in fibronectin when immobilized on the surface. A negatively-charged surface yields an open and filamentous fibronectin which significantly improves endothelial cell adhesion.
Cross-linked poly(dimethylaminoethyl acrylamide) coated magnetic nanoparticles: a high loaded, retrievable, and stable basic catalyst for the synthesis of benzopyranes in water
Authors: Zohreh Nasrin , Hosseini Seyed Hassan , Pourjavadi Ali , Bennett Craig
Published: September 2014

A high loaded basic magnetic catalyst was synthesized using a distillation–precipitation–polymerization method. The catalyst shows high activity in water for the synthesis of 4H-benzopyrans.
One-pot electrochemical synthesis of polydopamine coated magnetite nanoparticles
Authors: Mazario Eva , Sánchez-Marcos Jorge , Menéndez Nieves , Herrasti Pilar , García-Hernández Mar , Muñoz-Bonilla Alexandra
Published: September 2014

Herein a facile and versatile one step synthesis of magnetite nanoparticles coated with polydopamine is described.
Microwave-assisted, tetrabutylammonium hydroxide catalysed 1,4-addition of water to α,β-unsaturated ketones and α,β-ynones in aqueous solution
Authors: Lee Hyejeong , Jun Chul-Ho
Published: September 2014

Microwave-assisted, tetrabutylammonium hydroxide catalysed 1,4-addition reactions of water to α,β-unsaturated ketones and α,β-ynones take place efficiently in water.
Integration of Sn/C yolk–shell nanostructures into free-standing conductive networks as hierarchical composite 3D electrodes and the Li-ion insertion/extraction properties in a gel-type lithium-ion battery thereof
Authors: Ni Wei , Cheng Jianli , Shi Lingying , Li Xiaodong , Wang Bin , Guan Qun , Huang Ling , Gu Guifang , Li Hang
Published: September 2014

Complex Sn/C hollow elastic nanostructures integrated into flexible nanofibers as ideal 3D composite electrodes were preliminarily developed with energy-related potentials.
Engineering of biomimetic nanofibrous matrices for drug delivery and tissue engineering
Authors: He Chuanglong , Nie Wei , Feng Wei
Published: September 2014

Biomimetic nanofibrous matrices were fabricated by electrospinning, phase separation and molecular self-assembly for drug delivery and tissue engineering applications.
Physical apparatus parameters and model for vibrating tube densimeters at pressures to 140 MPa and temperatures to 473 K
Authors: May Eric F. , Tay Weparn J. , Nania Manuela , Aleji Amos , Al-Ghafri Saif , Martin Trusler J. P.
Published: September 2014

Vibrating tube densimeters are well-established tools for measuring fluid densities precisely at elevated temperatures and pressures. However, the conventional method of calibrating them utilises a model in which the apparatus parameters are represented as polynomials of temperature and pressure that contain a variable number of terms. Here a robust, physically-based model is presented and demonstrated for six different instruments at temperatures from (273 to 473) K, pressures from (0 to 140) MPa, and densities from (0 to 1050) kg m−3. The model's physical basis ensures that only seven apparatus parameters are required to relate the measured resonant period to fluid mass density with an average r.m.s. deviation of ±0.23 kg m‑3 across all six densimeters. Estimates for each of the apparatus parameters were made based on the geometry and material properties of the vibrating tubes, and these estimates were consistent with the parameter values determined by calibration with reference fluids. Three of the apparatus parameters describe the temperature dependence of the resonant period: for the six vibrating tubes tested, the relative standard deviations of these parameters were all within the range of values estimated from the thermoelastic properties of the Hastelloy tubes. Two distinct parameters are required to describe the pressure dependence of the vibrating tube's volume and effective spring constant, both of which are estimable from equations describing the elastic deformation of thick-walled tubes. The extensive calibrations conducted demonstrate that, for these densimeters, the variations with pressure of the tube's spring constant and its volume have a ratio that is neither 0 nor 1, as has been assumed previously. The model's physical basis allows vibrating tube densimeters to be calibrated accurately using fewer reference fluid measurements than required by the conventional method. Furthermore, use of the physically-based model reduces the uncertainty of measurements made at densities, temperatures, or pressures beyond the range of the calibration.
Mass-scaling replica-exchange molecular dynamics optimizes computational resources with simpler algorithm
Authors: Nagai Tetsuro , Takahashi Takuya
Published: September 2014

We develop a novel method of replica-exchange molecular dynamics (REMD) simulation, mass-scaling REMD (MSREMD) method, which improves numerical stability of simulations. In addition, the MSREMD method can also simplify a replica-exchange routine by eliminating velocity scaling. As a pilot system, a Lennard-Jones fluid is simulated with the new method. The results suggest that the MSREMD method improves the numerical stability at high temperatures compared with the conventional REMD method. For the Nosé-Hoover thermostats, we analytically demonstrate that the MSREMD simulations can reproduce completely the same trajectories of the conventional REMD ones with shorter time steps at high temperatures. Accordingly, we can easily compare the computational costs of the REMD and MSREMD simulations. We conclude that the MSREMD method decreases the instability and optimizes the computational resources with simpler algorithm.
Transient behaviour of a polymer dragged through a viscoelastic medium
Authors: Vandebroek Hans , Vanderzande Carlo
Published: September 2014

We study the dynamics of a polymer that is pulled by a constant force through a viscoelastic medium. This is a model for a polymer being pulled through a cell by an external force, or for an active biopolymer moving due to a self-generated force. Using the Rouse model with a memory dependent drag force, we find that the center of mass of the polymer follows a subballistic motion. We determine the time evolution of the length and the shape of the polymer. Through an analysis of the velocity of the monomers, we investigate how the tension propagates through the polymer. We discuss how polymers can be used to probe the properties of a viscoelastic medium.
Kinetics of exciplex formation/dissipation in reaction following Weller Scheme II
Authors: Fedorenko S. G. , Burshtein A. I.
Published: September 2014

Creation of exciplexes from the charged products of photoionization is considered by means of Integral Encounter Theory. The general kinetic equations of such a reaction following the Weller scheme II are developed. The special attention is given to the particular case of irreversible remote ionization of primary excited electron donor. Kinetics of exciplex formation is considered at fast biexponential geminate transformation of exciplexes in cage that gives way to subsequent bulk reaction of equilibrated reaction products controlled by power law recombination of ions. It is shown that the initial geminate stage of exciplex kinetics is observed only in diffusion controlled regime of the reaction and disappears with increasing mobility of ions in passing to kinetic regime. The quantum yield of exciplexes is studied along with their kinetics.
Design, conditioning, and performance of a high voltage, high brightness dc photoelectron gun with variable gap
Authors: Maxson Jared , Bazarov Ivan , Dunham Bruce , Dobbins John , Liu Xianghong , Smolenski Karl
Published: September 2014

A new high voltage photoemission gun has been constructed at Cornell University which features a segmented insulator and a movable anode, allowing the cathode-anode gap to be adjusted. In this work, we describe the gun's overall mechanical and high voltage design, the surface preparation of components, as well as the clean construction methods. We present high voltage conditioning data using a 50 mm cathode-anode gap, in which the conditioning voltage exceeds 500 kV, as well as at smaller gaps. Finally, we present simulated emittance results obtained from a genetic optimization scheme using voltage values based on the conditioning data. These results indicate that for charges up to 100 pC, a 30 mm gap at 400 kV has equal or smaller 100% emittance than a 50 mm gap at 450 kV, and also a smaller core emittance, when placed as the source for the Cornell energy recovery linac photoinjector with bunch length constrained to be <3 ps rms. For 100 pC up to 0.5 nC charges, the 50 mm gap has larger core emittance than the 30 mm gap, but conversely smaller 100% emittance.
Anisotropic mobility of particles near the interface of two immiscible liquids
Authors: Wang W. , Huang P.
Published: September 2014

Three-dimensional mobility of colloidal particles in the close vicinity of a liquid-liquid interface is experimentally quantified and compared with established theories. Evanescent wave-based particle tracking velocimetry is used to measure the Brownian motion of fluorescent spheres near an interface between water and non-polar oil. The experimental results confirm that the mobility of particles suspended in the less viscous liquid is anisotropically suppressed. The measured hindered mobility are in agreement with theoretical models.
Point defects as a test ground for the local density approximation +U theory: Mn, Fe, and VGa in GaN
Authors: Volnianska O. , Zakrzewski T. , Boguslawski P.
Published: September 2014

Electronic structure of the Mn and Fe ions and of the gallium vacancy VGa in GaN was analysed within the GGA + U approach. First, the +U term was treated as a free parameter, and applied to p(N), d(Mn), and d(Fe). The band gap of GaN is reproduced for U(N) ≈ 4 eV. The electronic structure of defect states was found to be more sensitive to the value of U than that of the bulk states. Both the magnitude and the sign of the U-induced energy shifts of levels depend on occupancies, and thus on the defect charge state. The energy shifts also depend on the hybridization between defect and host states, and thus are different for different level symmetries. In the case of VGa, these effects lead to stabilization of spin polarization and the “negative-Ueff” behavior. The values of Us were also calculated using the linear response approach, which gives U(Fe) ≈ U(Mn) ≈ 4 eV. This reproduces well the results of previous hybrid functionals calculations. However, the best agreement with the experimental data is obtained for vanishing or even negative U(Fe) and U(Mn).
Covalent dependence of octahedral rotations in orthorhombic perovskite oxides
Authors: Cammarata Antonio , Rondinelli James M.
Published: September 2014

The compositional dependence of metal-oxygen BO6 octahedral distortions, including bond elongations and rotations, is frequently discussed in the ABO3 perovskite literature; structural distortions alleviate internal stresses driven by under- or over-coordinated bond environments. Here we identify the dependence of octahedral rotations from changes in metal-oxygen bond covalency in orthorhombic perovskites. Using density functional theory we formulate a covalency metric, which captures both the real and k-space interactions between the magnitude and sense, i.e., in-phase or out-of-phase, octahedral rotations, to explore the link between the ionic-covalent Fe–O bond and the interoctahedral Fe–O–Fe bond angles in Pbnm ferrates. Our survey finds that the covalency of the metal–oxygen bond is correlated with the rotation amplitude: We find the more covalent the Fe-O bond, the less distorted is the structure and the more important the long-range inter-octahedral (Fe-O-Fe bond angle) interactions. Finally, we show how to indirectly tune the B-O bond covalency by A-cation induced BO6 rotations independent of ionic size, facilitating design of targeted bonding interactions in complex perovskites.
Wind-forced modulations in crossing sea states over infinite depth water
Authors: Debsarma Suma , Senapati Sudipta , Das K. P.
Published: September 2014

The present work is motivated by the work of Leblanc [“Amplification of nonlinear surface waves by wind,” Phys. Fluids 19, 101705 (2007)] which showed that Stokes waves grow super exponentially under fair wind as a result of modulational instability. Here, we have studied the effect of wind in a situation of crossing sea states characterized by two obliquely propagating wave systems in deep water. It is found that the wind-forced uniform wave solution in crossing seas grows explosively with a super-exponential growth rate even under a steady horizontal wind flow. This is an important piece of information in the context of the formation of freak waves.
Towards plug and play filling of microfluidic devices by utilizing networks of capillary stop valves
Authors: Hagmeyer B. , Zechnall F. , Stelzle M.
Published: September 2014

Robust bubble-free priming of complex microfluidic chips represents a critical, yet often unmet prerequisite to enable their practical and widespread application. Towards this end, the usage of a network of capillary stop valves as a generic design feature is proposed. Design principles, numerical simulations, and their application in the development of a microfluidic cell culture device are presented. This chip comprises eight parallel chambers for the assembly and cultivation of human hepatocytes and endothelial cells. The inlet channel divides into cell chambers, after which the flows are reunited to a single chip outlet. Dimensions and geometry of channels and cell chambers are designed to yield capillary burst pressures sequentially increasing towards the chip outlet. Thus, progress of liquid flow through the device is predefined by design and enclosure of air bubbles inside the microfluidic structures is efficiently avoided. Capillary stop valves were designed using numerical simulations. Devices were fabricated in cyclic olefin polymer. Pressure during filling was determined experimentally and is in good agreement with data obtained from simulation.
Positional control of plasmonic fields and electron emission
Authors: Word R. C. , Fitzgerald J. P. S. , Könenkamp R.
Published: September 2014

We report the positional control of plasmonic fields and electron emission in a continuous gap antenna structure of sub-micron size. We show experimentally that a nanoscale area of plasmon-enhanced electron emission can be motioned by changing the polarization of an exciting optical beam of 800 nm wavelength. Finite-difference calculations are presented to support the experiments and to show that the plasmon-enhanced electric field distribution of the antenna can be motioned precisely and predictively.
Large positive magnetoresistance in germanium
Authors: Chen Jiaojiao , Zhang Xiaozhong , Luo Zhaochu , Wang Jimin , Piao Hong-Guang
Published: September 2014

A large positive magnetoresistance (MR) effect is observed in In/Ge/In structures. The current–voltage characteristics of the structure show a nonlinear behavior (even breakdown at higher voltages), caused by the space-charge effect. It is found that large magnetic field and low temperature can suppress the breakdown, resulting in a large value of MR. The MR is measured to be 1300% with the external magnetic field of 2 T and applied voltage of only 8.5 V at room temperature. This work may be beneficial to the germanium based magnetic sensing industry.
Use of a low pressure helium/water vapor discharge as a mercury-free source of ultraviolet emission
Authors: Levko Dmitry , Shuaibov Alexander , Shevera Igor , Gritzak Roksolana , Tsymbaliuk Alexander
Published: September 2014

This paper presents the results of study of the longitudinal low-pressure glow discharge in a helium/water mixture. This discharge is proposed for use as a mercury-free source of ultraviolet emission. The emission spectra in the ultraviolet range are recorded by a monochromator and analyzed. In order to interpret the experimental results, the numerical modeling is carried out using global model for 46 species and 577 plasma chemical reactions between them. This model allows us to define the main reactions responsible for the generation and quenching of the excited species, which emit in the ultraviolet range. The optimal conditions are found when the lines with wavelengths of 309 nm OH(A-X) and 150–190 nm OH(X-C,B) have the largest intensity.
Ultrafast laser induced periodic sub-wavelength aluminum surface structures and nanoparticles in air and liquids
Authors: Kuladeep Rajamudili , Dar Mudasir H. , Deepak K. L. N. , Rao D. Narayana
Published: September 2014

In this communication, we demonstrate the generation of laser-induced periodic sub-wavelength surface structures (LIPSS) or ripples on a bulk aluminum (Al) and Al nanoparticles (NPs) by femtosecond (fs) laser direct writing technique. Laser irradiation was performed on Al surface at normal incidence in air and by immersing in ethanol (C2H5OH) and water (H2O) using linearly polarized Ti:sapphire fs laser pulses of ∼110 fs pulse duration and ∼800 nm wavelength. Field emission scanning electron microscope is utilized for imaging surface morphology of laser written structures and it reveals that the spatial periodicity as well as the surface morphology of the LIPSS depends on the surrounding dielectric medium and also on the various laser irradiation parameters. The observed LIPSS have been classified as low spatial frequency LIPSS which are perpendicularly oriented to the laser polarization with a periodicity from 460 to 620 nm and high spatial frequency LIPSS which spectacles a periodicity less than 100 nm with the orientation parallel to the polarization of the incident laser beam. Fabricated colloidal solutions, which contain the Al NPs, were characterized by UV-Vis absorption spectroscopy and transmission electron microscopy (TEM). TEM results reveal the formation of internal cavities in Al NPs both in ethanol and water. Formation mechanism of LIPSS and cavities inside the nanoparticles are discussed in detail.
Surface driven effects on magnetic properties of antiferromagnetic LaFeO3 nanocrystalline ferrite
Authors: Sendil Kumar A. , Manivel Raja M. , Bhatnagar Anil K.
Published: September 2014

LaFeO3 nanocrystalline ferrites were synthesized through sol-gel method in different size distributions and the effect of finite size on magnetic properties is investigated. Results of magnetization and Mössbauer measurements show that superparamagnetism and weak ferromagnetic behavior in some of the size distributions. The origin of the superparamagnetism is from fine particles similar to ferromagnetic single domains and the weak ferromagnetism comes from surface spin disorder caused by Dzyaloshinskii-Moriya interaction. The magnetic ground state of LaFeO3 nanoparticles differs from that of bulk, and the ground state is dictated by the finite size effect because density of states depends on the dimensionality of the sample.
A combined microfluidic-microstencil method for patterning biomolecules and cells
Authors: Rana Kuldeepsinh , Timmer Benjamin J. , Neeves Keith B.
Published: September 2014

Despite the myriad of soft lithography based micropatterning methods available to researchers, it is still challenging to define small features (10–100 μm) that are spaced far apart (1–10 mm). In this report, we describe a combined microfluidic-microstencil patterning method that can produce multifunctional substrates of small features, O(10 μm), with a large pitch, O(1 mm). In that, we fabricate microstencils using an UV curable polyurethane (Norland Optical Adhesive 81) with dense arrays of 10–100 μm holes. Overlaying arrays of microfluidic channels over these microstencils allow for the control of the spacing between features and the ability to pattern multiple substrates. We show that this method is capable of patterning soluble proteins, fibrillar insoluble collagen, liposomes, cells, and nanoparticles. We demonstrate the utility of the method by measuring platelet adhesion under flow to three adhesive proteins (insoluble fibrillar collagen, laminin, and reconstituted acid solubilized collagen fibers) in a single assay.
Electric field induced localization phenomena in a ladder network with superlattice configuration: Effect of backbone environment
Authors: Dutta Paramita , Maiti Santanu K. , Karmakar S. N.
Published: September 2014

Electric field induced localization properties of a tight-binding ladder network in presence of backbone sites are investigated. Based on Green's function formalism we numerically calculate two-terminal transport together with density of states for different arrangements of atomic sites in the ladder and its backbone. Our results lead to a possibility of getting multiple mobility edges which essentially plays a switching action between a completely opaque to fully or partly conducting region upon the variation of system Fermi energy, and thus, support in fabricating mesoscopic or DNA-based switching devices.
Temperature dependency of the emission properties from positioned In(Ga)As/GaAs quantum dots
Authors: Braun T. , Schneider C. , Maier S. , Igusa R. , Iwamoto S. , Forchel A. , Höfling S. , Arakawa Y. , Kamp M.
Published: September 2014

In this letter we study the influence of temperature and excitation power on the emission linewidth from site-controlled InGaAs/GaAs quantum dots grown on nanoholes defined by electron beam lithography and wet chemical etching. We identify thermal electron activation as well as direct exciton loss as the dominant intensity quenching channels. Additionally, we carefully analyze the effects of optical and acoustic phonons as well as close-by defects on the emission linewidth by means of temperature and power dependent micro-photoluminescence on single quantum dots with large pitches.
An enzyme-linked immunosorbent assay on a centrifugal platform using magnetic beads
Authors: Shih Chih-Hsin , Wu Ho-Chin , Chang Chong-Yi , Huang Wen-Hong , Yang Yi-Feng
Published: September 2014

An automated, disk-based, enzyme-linked immunosorbent assay (ELISA) system is presented in this work. Magnetic beads were used as the antibody carriers to improve the assay sensitivity and shorten the reaction time. The magnetic module integrated on the system is capable of controlling the magnetic beads to either move in the incubation stage or immobilize at a specific location during washing stage. This controlling mechanism utilizes a passive controlling approach so that it can be performed through disk spinning without the need of active control from external devices. The movement of the magnetic beads was investigated and the optimal rotational speed was found to be related to the ratio of the processing time to the cycle time of the magnetic beads. Comparing to ELISA conducted on microtiter plates, similar test results could be achieved by the disk-based ELISA but the entire protocol can be finished automatically within 45 min with much less reagent consumption.
Regioselective Dye-Induced Photocleavage of Epoxides as an Alternative Mild Synthetic Route to a Targeted Alcohol Functionality
Authors: Provatas Anthony A. , Epling Gary A. , Stuart James D. , Yeudakimau Aliaksandr
Published: September 2014

The regioselective cleavage of epoxides using visible light and a catalytic dye is reported in this study as an alternative mild synthetic approach. The epoxide radical anion is generated via visible light in an electron transfer reaction, induced by non-toxic dyes, leading to ring opening and formation of the corresponding alcohol with the hydroxyl group on the less substituted carbon in excellent yields.