bluuebunny/crossref_metadata_2025 huggingface dataset:
Newly Synthesized Photocrosslinkable Liquid-Crystalline Polymers and their Properties
Authors: Kumar G. , Subramanian K.
Published: November 2014

This chapter deals with a hitherto unreported newer root of synthesis of photocrosslinkable polymers containing pendant chalcone moieties with different substituents. The main aim of present research work is to synthesis photocrosslinkable polymers containing pendant chalcone moiety that exhibits both liquid-crystalline and photocrosslinking properties. The polymers were synthesized with various substituents in their terminal position to pendant chalcone unit and acrylic unit. All the five polymers P1–P5 were synthesized by the free-radical polymerization method. The predetermined quantities of monomers were dissolved in THF solvent and AIBN was used as initiator. The polymerization was carried out under nitrogen (inert) atmosphere for 48 h. The number (Mn) and weight average (Mw) molecular weight of the polymers were obtained by the gel permeation chromatography (GPC) method. The thermogravimetric analysis (TGA) results indicate that the polymers show good thermal stability, since the phenyl group in the case of polymers P1, P2 and P4 gives better thermal and thermal oxidative stability required for a negative photoresists. Liquid-crystalline behavior of polymers were identified by DSC thermogram and confirmed by hot-stage polarized optical microscope images. Photocrosslinking behavior of all the polymers were investigated by UV-Vis spectroscopy, the cross linking of all the polymers proceed via cyclobutane ring formation during 2π+2π cycloaddition reaction on irradiation with 254-nm UV light. The surface morphology studies of both virgin and photocrosslinked polymers were investigated by scanning electron microscope (SEM) analysis. The photocrosslinked polymer sample confirms the loosely held dispersion of polymeric material, while virgin polymer exhibits compact stringent dispersion of the polymeric surface.
Lamellar and Circular Constructs Containing Self-Aligned Liquid Crystals
Authors: De Sio Luciano , Tabiryan Nelson , Bunning Timothy
Published: November 2014

Holography and lithography allow realization of curved periodic microstructures comprising self-aligned liquid crystal (LC)s. The fabrication concept is based on phase separation of mixture of a photocurable polymer and a LC. Exploitation of an interference pattern allows realization of a periodic nano/microcomposite holographic grating made of slices of almost pure polymer alternating with well-aligned channels of LC. By means of a “Fresnel like” curing pattern, curved polymeric slices can impose radial alignment of nematic LCs. The distinctive features of the periodic structures enable high-quality and self-alignment of ordered fluids without the need for surface chemistry or functionalization.
Technical Background
Authors: Rottmann Lothar , Jakubowski Norbert , Konegger-Kappel Stefanie , Hanousek Ondrej , Prohaska Thomas
Published: November 2014

This chapter presents all major components of a sector field mass spectrometer. Sample introduction systems (manual and continuous), ion sources (plasma sources, beam sources, thermal ionization sources), sampling interface, electrostatic lens system, slit system, magnetic sector, electric sector, flight tube, transfer optics, detection system (electron multipliers, Daly Detector, Faraday cup, focal plane detectors), and vacuum system are described in detail. Special focus was aimed to the dispersion in a magnetic field, because dispersion is directly related to the mass resolution achievable with the device. An overview of commonly applied arrangements of double-focusing mass spectrometers (forward and reverse Nier-Johnson, Mattauch-Herzog, and other geometries) is given in this chapter. 29 figures, both photographs and schematics, accompany the text for a better understanding and imagination of the technical background of a mass spectrometer.
Measurement Strategies
Authors: Irrgeher Johanna , Vogl Jochen , Santner Jakob , Prohaska Thomas
Published: November 2014

Designing an appropriate measurement strategy for a particular analytical question is not always a simple task, since a number of factors have to be considered, whereby some of them might be difficult to define. A set of key questions generally precede the experimental design in analytical measurements and help to choose the measurement strategy, which is fit for the intended use – in the particular case of the content of this book on sector field mass spectrometry – either for quantification, elemental ratio or isotope ratio analyses, accordingly. A set of considerations such as the definition of the analyte and the measurand, matrix composition, background levels, working range, requested measurement uncertainty or the availability of certified reference materials, contribute to the design of a measurement. Within the following sections, the focus will be mainly on considerations with respect to calibration in elemental and isotopic analysis. The basic principles of various calibration strategies (e.g. external calibration, internal normalization, standard addition, isotope dilution) for quantification will be described along with calibration strategies used in isotope ratio mass spectrometry (e.g. internal/external intra- and inter- elemental corrections, double spike techniques, isotope pattern deconvolution). Finally, the most relevant equation models for the correction of instrumental isotopic fractionation are given.
Metrology
Authors: Irrgeher Johanna , Prohaska Thomas
Published: November 2014

In the ‘Vocabulaire International de Métrologie’ (VIM) as published by the ‘Bureau International des Poids et Mésures’ (BIPM) the term ‘metrology’ is defined as “the science of measurement and its application” and covers all theoretical and practical aspects of any measurement, including uncertainty and field of application. This book chapter on metrology summarizes the basic metrological terminology related to inorganic sector field mass spectrometry. General terminology and explanatory notes on terms related to e.g. validation, uncertainty and calibration is given, where VIM-based terminology is compared to and supplemented by IUPAC-based definitions and recommendations. A compact overview about the most relevant metrological institutions worldwide is given in order to provide insight into the organization of metrological network institutions. Metrological traceability, which is required for the establishment of a calibration hierarchy, providing that all input parameters into a model equation are traceable to a common reference (e.g. the SI-unit) is defined together with related aspects such as the use of reference materials. The principle of the estimation of a sound measurement uncertainty is presented. This book chapter should contribute to the mutual understanding of metrological terminology being used within the scientific community.
Magnetic Sector Field Instruments
Authors: Prohaska Thomas
Published: November 2014

In this introduction to the subsequent chapters dealing with the currently most important types of elemental and isotopic mass spectrometers using a magnetic sector field, the most relevant instrumental manufacturers in the field of sector field mass spectrometers are shortly described including short sketches on the companies' history and major core areas. As a unique asset, a comprehensive table presents technical specifications of all currently commercially available sector field instruments.
Thermal Ionisation Mass Spectrometry
Authors: Bürger Stefan , Vogl Jochen , Kloetzli Urs , Nunes Laurie , Lavelle Mark
Published: November 2014

Thermal ionisation, also known as surface ionisation, was one of the first ionisation techniques developed for mass spectrometry, having been invented as early as 1918. The ionization process, described by the empirically derived “fractionation laws”, is widely understood. Isotope ratio measurements can be achieved with high precision and accuracy. Due to this, thermal ionisation has paved the way for great scientific achievements including: the discovery of new isotopes, the determination of radioactive half-lives and atomic weights of the elements, the accurate determination of the age of the earth and investigations on human society in the past such as mobility and trade. TIMS is still regarded as ‘golden standard’ in isotope ratio measurements. Thus the method is a reference technique that remains at the forefront of isotopic analysis particularly in the fields of metrology. A concise overview is given here of the technical background of thermal ionisation as well as the numerous applications of this technique in earth sciences, industry, metrology, and nuclear forensics.
Secondary Ion Mass Spectrometry
Authors: Sangely Laure , Boyer Bernard , de Chambost Emmanuel , Valle Nathalie , Audinot Jean-Nicolas , Ireland Trevor , Wiedenbeck Michael , Aléon Jérôme , Jungnickel Harald , Barnes Jean-Paul , Bienvenu Philippe , Breuer Uwe
Published: November 2014

In Secondary Ion Mass Spectrometry (SIMS) a focused beam of energetic ions (so-called primary ions) is targeted onto the surface of a solid sample. Primary ions dissipate their energy, leading to the sputtering and ionisation of the outmost atoms of the sample surface. The resulting secondary ions are accelerated and transferred to a magnetic analyser. SIMS is applicable to the determination of the isotopic and trace, minor (and to some limited extent, major) element composition across the entire periodic table for any solid material compatible with high-vacuum conditions. Elemental and isotopic analysis can be performed locally down to the nm scale or along depth profiles resulting in 2D surface (ion imaging) or 3D volume (ion tomography) images with a resolution range between 50 nm and 5 μm. A concise overview of the technical background of secondary ionisation as well as the numerous applications of this technique in geochemistry and cosmochemistry, material science, Nuclear Safeguards and life sciences is given.
Glucose-sensitive nanofiber scaffolds with an improved sensing design for physiological conditions
Authors: Balaconis Mary K. , Luo Yi , Clark Heather A.
Published: November 2014

Based on the enhanced sensitivity of the new boronic acids and the residency time of nanofibers, this sensor configuration is an important step towards continuous monitoring for glucose and other analytes.
Simple and useful method for determination of inorganic selenium species in real samples based on UV-VIS spectroscopy in a micellar medium
Authors: Ulusoy Halil İbrahim
Published: November 2014

A preconcentration and determination methodology utilizing the cloud point phenomenon was developed for the determination of inorganic selenium species using UV-VIS spectrophotometry.
Formation of ring-in-ring complexes between crown ethers and rigid TVBox8+
Authors: Sun Junling , Frasconi Marco , Liu Zhichang , Barnes Jonathan C. , Wang Yuping , Chen Dongyang , Stern Charlotte L. , Fraser Stoddart J.
Published: November 2014

An octacationic tetraviologen-based cyclophane—so called TVBox8+—can form a ring-in-ring complex with bis-1,5-dinaphtho[50]crown-14, which represents a key intermediate for constructing molecular Borromean rings in a stepwise manner.
Formal [3+2] cycloaddition of Ugi adducts towards pyrrolines
Authors: Ben Abdessalem Abdelbari , Abderrahim Raoudha , Agrebie Asma , Dos Santos Aurélie , El Kaïm Laurent , Komesky Andrew
Published: November 2014

Pyrroline formation from Ugi adducts: an unusual [3+2] cycloaddition of amides with Michael acceptors.
Activation of carbon-supported catalysts by ozonized acidic solutions for the direct implementation in (electro-)chemical reactors
Authors: Baldizzone C. , Mezzavilla S. , Hodnik N. , Zeradjanin A. R. , Kostka A. , Schüth F. , Mayrhofer K. J. J.
Published: November 2014

Development of a novel and scalable ex situ technique for the simultaneous activation/dealloying of Pt-based nanocatalysts for energy conversion applications.
γ-Silylboronates in the chiral Brønsted acid-catalysed allylboration of aldehydes
Authors: Barrio Pablo , Rodríguez Elsa , Saito Kodai , Fustero Santos , Akiyama Takahiko
Published: November 2014

The use of functionalised allylboronates in the catalytic enantioselective allylation of aldehydes is described for the first time. γ-Silylallyl pinacolate derivatives give rise to α-silyl homoallylic alcohols, useful intermediates as showcased by their transformation into fluorinated allylic alcohols.
Iron-mediated Markovnikov-selective hydro-trifluoromethylthiolation of unactivated alkenes
Authors: Yang Tao , Lu Long , Shen Qilong
Published: November 2014

An iron-mediated hydro-trifluoromethylthiolation of unactivated olefins under mild conditions was described for the first time.
Dual stimuli-responsive multi-drug delivery system for the individually controlled release of anti-cancer drugs
Authors: Xiao Wang , Zeng Xuan , Lin Hang , Han Kai , Jia Hui-Zhen , Zhang Xian-Zheng
Published: November 2014

A dual stimuli-responsive multi-drug delivery system was developed for “cancer cocktail therapy”. Release behaviors of the dual drugs could be controlled separately by appropriate stimulation.
A tale of two forces: simultaneous chemical and acoustic propulsion of bimetallic micromotors
Authors: Wang Wei , Duan Wentao , Zhang Zexin , Sun Mei , Sen Ayusman , Mallouk Thomas E.
Published: November 2014

Bimetallic gold–ruthenium microrods are propelled in opposite directions in water by ultrasound and by catalytic decomposition of hydrogen peroxide.
P–P σ-bond activation by gold(I) coordination
Authors: Hinz Alexander , Schulz Axel , Villinger Alexander
Published: November 2014

Bond activation by gold is of imminent interest with respect to small molecule activation.
Shape-controlled synthesis of phosphor K2SiF6:Mn4+nanorods and their luminescence properties
Authors: Li Xiaoqing , Su Xiangming , Liu Ping , Liu Jie , Yao Zhiling , Chen Jiajun , Yao Hui , Yu Xibin , Zhan Ming
Published: November 2014

A red phosphor K2SiF6:Mn4+nanorod is successfully prepared through an efficient one-step method at room temperature for 30 min. Under UV excitation, K2SiF6:Mn4+nanorods show better red emission corresponding to the characteristic lines of Mn4+compared to bulk materials.
Bulk crystal growth of hybrid perovskite material CH3NH3PbI3
Authors: Dang Yangyang , Liu Yang , Sun Youxuan , Yuan Dongsheng , Liu Xiaolong , Lu Weiqun , Liu Guangfeng , Xia Haibing , Tao Xutang
Published: November 2014

Bulk crystal of tetragonal CH3NH3PbI3with dimensions of centimeters grown by a temperature-lowering method in HI solution is reported for the first time.
Influence of counter-anions during electrochemical deposition of ZnO on the charge transport dynamics in dye-sensitized solar cells
Authors: Richter Christoph , Beu Max , Schlettwein Derck
Published: November 2014

The density of available trap states in porous dye-sensitized ZnO electrodes can be controlled by the proper choice of the counter-anion during electrodeposition of the electrode. It is shown how the electrode kinetics and, hence, the photovoltaic cell properties can be tuned this way.
Surface redox chemistry and mechanochemistry of insulating polystyrene nanospheres
Authors: Varley Thomas S. , Rosillo-Lopez Martin , Sehmi Sandeep , Hollingsworth Nathan , Holt Katherine B.
Published: November 2014

Voltammetric response of electrode-immobilised polystyrene nanoparticles depends on prior mechanical agitation of polystyrene surface.
Silicon-pyrene/perylene hybrids as molecular rectifiers
Authors: Garg Kavita , Majumder Chiranjib , Nayak Sandip K. , Aswal Dinesh K. , Gupta Shiv K. , Chattopadhyay Subrata
Published: November 2014

Out of three pyrene/perylene based σ–π monolayers electro-grafted on Si, pyrene–CH2–O–(CH2)6– showed the highest rectification ratio of ∼105 in the forward bias.
Theoretical studies on the effect of a bithiophene bridge with different substituent groups (R = H, CH3, OCH3 and CN) in donor–π–acceptor copolymers for organic solar cell applications
Authors: Fu Zhiyong , Shen Wei , He Rongxing , Liu Xiaorui , Sun Huili , Yin Wanqiang , Li Ming
Published: November 2014

The design of a series of D–π–A copolymers.
Effects of 3d transition-metal doping on electronic and magnetic properties of MoS2nanoribbons
Authors: Tian Xiaoqing , Liu Lin , Du Yu , Gu Juan , Xu Jian-bin , Yakobson Boris I.
Published: November 2014

Distribution of the magnetization for Co-pair doped 10-ZMoS2NRs.
Electronic properties of PbX3CH3NH3(X = Cl, Br, I) compounds for photovoltaic and photocatalytic applications
Authors: Melissen Sigismund Teunis Alexander George , Labat Frédéric , Sautet Philippe , Le Bahers Tangui
Published: November 2014

Applying DFT (HSE + spin orbit coupling) computed properties to five perovskites in the PbX3CH3NH3(X = I, Br, Cl) family of photovoltaic materials reveals that they can exhibit several interfacial charge transfer mechanisms.
Spin effects in thermoelectric phenomena in SiC nanoribbons
Authors: Zberecki K. , Swirkowicz R. , Wierzbicki M. , Barnaś J.
Published: November 2014

Using ab initio methods we calculate the thermoelectric and spin thermoelectric properties of zigzag SiC nanoribbons, asymmetrically terminated with hydrogen.
Evidence of anti-parallel dimer formation of 4-cyano-4′-alkyl biphenyls in isotropic cyclohexane solution
Authors: Takabatake Shunzo , Shikata Toshiyuki
Published: November 2014

The formation of anti-parallel dimers ofnCBs was evidently confirmed by dielectric and fluorescence experiments even in isotropic cyclohexane solution.
A robust microporous metal–organic framework as a highly selective and sensitive, instantaneous and colorimetric sensor for Eu3+ ions
Authors: Gao Yanfei , Zhang Xueqiong , Sun Wei , Liu Zhiliang
Published: November 2014

A highly thermostable Mg-MOF with nanoscale pores acts as a highly selective, sensitive and instantaneous sensor for Eu3+ in a water solution.
Assembling anionic Sb(v)/(iii) containing polyoxostibonates stabilized by triphenyltellurium cations
Authors: Srungavruksham Nagarjuna Kumar , Baskar Viswanathan
Published: November 2014

Mixed valent polyoxostibonates ligated by tetraorganoditelluroxane and stabilized by weak interactions from triaryltellurium cations are presented. Successive reactions like reduction, dearylation and disproportionation have been observed en route to the formation of these novel POMs.
A study on the formation of the nitro radical anion by ornidazole and its significant decrease in a structurally characterized binuclear Cu(II)-complex: impact in biology
Authors: Santra Ramesh Chandra , Ganguly Durba , Singh Jyotsna , Mukhopadhyay Kasturi , Das Saurabh
Published: November 2014

An acetate-bridged binuclear Cu(II)complex of the antiparasitic drug ornidazole is able to decrease the formation of the nitro radical anion.
Occurrence, seasonal variation and removal efficiency of antibiotics and their metabolites in wastewater treatment plants, Jiulongjiang River Basin, South China
Authors: Zhang Han , Du Miaomiao , Jiang Hongyou , Zhang Dandan , Lin Lifeng , Ye Hong , Zhang Xian
Published: November 2014

Wastewater treatment plants (WWTPs) are regarded as one of the most important sources of antibiotics in the environment.
Seven questions when deciding where to submit
Authors: Wania Frank
Published: November 2014

Frank Wania, Chair of the Editorial Board poses seven questions to consider prior to submitting a scientific manuscript.
Lactobacillus rhamnosus LA68 and Lactobacillus plantarum WCFS1 differently influence metabolic and immunological parameters in high fat diet-induced hypercholesterolemia and hepatic steatosis
Authors: Ivanovic Nevena , Minic Rajna , Dimitrijevic Ljiljana , Radojevic Skodric Sanja , Zivkovic Irena , Djordjevic Brizita
Published: November 2014

TwoLactobacillusstrains were evaluated for their effects on high fat diet induced pathology in mice.
Direct analysis of dried blood spots by femtosecond-laser ablation-inductively coupled plasma-mass spectrometry. Feasibility of split-flow laser ablation for simultaneous trace element and isotopic analysis
Authors: Aramendía M. , Rello L. , Bérail S. , Donnard A. , Pécheyran C. , Resano M.
Published: November 2014

This work presents a method that enables the direct elemental and isotopic analysis of dried blood spots using LA-ICPMS.
Serum metabolomics analysis reveals impaired lipid metabolism in rats after oral exposure to benzo(a)pyrene
Authors: Wang Xiaoxue , Zhang Jie , Huang Qingyu , Alamdar Ambreen , Tian Meiping , Liu Liangpo , Shen Heqing
Published: November 2014

A metabolomics study was conducted to unveil the metabolic profiling of rats exposed to benzo(a)pyrene, and twelve differentiated metabolites were identified.
Linear dialdehydes as promising substrates for aminocatalyzed transformations
Authors: Kumar Indresh , Ramaraju Panduga , Mir Nisar A. , Singh Anoop
Published: November 2014

Linear dialdehydes: This article summarizes the recent utilization of linear dialdehydes as appropriate substrates for amine catalyzed cascade/domino transformations.
Chitosan oligosaccharide copolymer micelles with double disulphide linkage in the backbone associated by H-bonding duplexes for targeted intracellular drug delivery
Authors: Yang Qinglai , He Changyu , Xu Yuhong , Liu Bingya , Shao Zhifeng , Zhu Zhenggang , Hou Yongtai , Gong Bing , Shen Yu-Mei
Published: November 2014

Folic acid conjugated block copolymer micelles with H-bonding associated double disulphide linkage in the backbone were developed.
Fabrication and electrochemical characterization of Pt–Pd impregnated nanocomposite polymer electrolyte membranes for high concentration DMFCs
Authors: Pethaiah Sethu Sundar , Ulaganathan Mani , Ramalinga Viswanathan Mangalaraja , Chan Siew Hwa
Published: November 2014

Bimetallic Pt–Pd impregnated nanocomposite polymer electrolyte membranes were prepared and the influence of Pd on Pt was evaluated towards a single cell performance.
Structural modification of acrylonitrile–butadiene–styrene waste as an efficient nanoadsorbent for removal of metal ions from water: isotherm, kinetic and thermodynamic study
Authors: Masoumi Arameh , Hemmati Khadijeh , Ghaemy Mousa
Published: November 2014

An environmentally benign approach for the structural modification of ABS waste and its use for the removal of heavy metal ions from aqueous solutions have been described using isotherm, kinetics and thermodynamic studies.
An in vitro cytotoxicity study of 5-fluorouracil encapsulated chitosan/gold nanocomposites towards MCF-7 cells
Authors: Nivethaa E. A. K. , Dhanavel S. , Narayanan V. , Vasu C. Arul , Stephen A.
Published: November 2014

Schematic outlining the synthesis of 5FU loaded CS/Au nanocomposite and its application.
Graphene/carbon aerogels derived from graphene crosslinked polyimide as electrode materials for supercapacitors
Authors: Zhang Youfang , Fan Wei , Huang Yunpeng , Zhang Chao , Liu Tianxi
Published: November 2014

Graphene/carbon aerogels with hierarchical pores have been facilely prepared by carbonization of graphene/polyimide aerogels.
Carbazole-based molecular tweezers as platforms for the discrimination of heavy metal ions
Authors: Hwang In-hwan , Hong kyeong-Im , Jeong Kyu-Sung , Jang Woo-Dong
Published: November 2014

Eight carbazole-based molecular tweezers were synthesized for application in the discrimination of heavy metal ions.
Synthesis and biological evaluation of santacruzamate A and analogs as potential anticancer agents
Authors: Liu Qi , Lu Wenhua , Ma Mingzhe , Liao Jianwei , Ganesan A. , Hu Yumin , Wen Shijun , Huang Peng
Published: November 2014

After a SAR study of santacruzamate A, 5 was discovered to selectively inhibit the growth of malignant cancer cells.
Protein ubiquitination and formation of polyubiquitin chains without ATP, E1 and E2 enzymes
Authors: Park Sungjin , Krist David T. , Statsyuk Alexander V.
Published: November 2014

Protein ubiquitination without ATP. This paper reports a chemical strategy to ubiquitinate proteins without ATP, E1, and E2 enzymes, offering new insights on the biochemical mechanism of E3s.
Highly efficient nitrate ester explosive vapor probe based on multiple triphenylaminopyrenyl-substituted POSS
Authors: Gao Yixun , Xu Wei , Zhu Defeng , Chen Lei , Fu Yanyan , He Qingguo , Cao Huimin , Cheng Jiangong
Published: November 2014

With nano and polar POSS core and eight luminescent branches, P8PT presents excellent fluorescence quenching efficiency for nitroglycerin vapor.
Optimal state feedback control for wireless networked control systems with decentralised controllers
Authors: Wang Zhuwei , Wang Xiaodong , Liu Lihan , Huang Mo
Published: November 2014

In this study, the design of the optimal decentralised full‐state‐feedback controllers is derived for wireless networked control systems with network‐induced delays. In particular, the authors formulate the optimal decentralised control problem as a non‐cooperative linear quadratic game. Then, the optimal control strategy of each controller is obtained that is based on the current plant state and the last control strategies of decentralised controllers. The proposed optimal decentralised controllers reduce to the known controller under certain conditions. Moreover, the authors illustrate the application of the proposed decentralised state feedback control to load frequency control in power grid systems.
Iterated binomial sums and their associated iterated integrals
Authors: Ablinger J. , Blümlein J. , Raab C. G. , Schneider C.
Published: November 2014

We consider finite iterated generalized harmonic sums weighted by the binomial \documentclass[12pt]{minimal}\begin{document}$\binom{2k}{k}$\end{document}2kk in numerators and denominators. A large class of these functions emerges in the calculation of massive Feynman diagrams with local operator insertions starting at 3-loop order in the coupling constant and extends the classes of the nested harmonic, generalized harmonic, and cyclotomic sums. The binomially weighted sums are associated by the Mellin transform to iterated integrals over square-root valued alphabets. The values of the sums for N → ∞ and the iterated integrals at x = 1 lead to new constants, extending the set of special numbers given by the multiple zeta values, the cyclotomic zeta values and special constants which emerge in the limit N → ∞ of generalized harmonic sums. We develop algorithms to obtain the Mellin representations of these sums in a systematic way. They are of importance for the derivation of the asymptotic expansion of these sums and their analytic continuation to \documentclass[12pt]{minimal}\begin{document}$N \in \mathbb {C}$\end{document}N∈C. The associated convolution relations are derived for real parameters and can therefore be used in a wider context, as, e.g., for multi-scale processes. We also derive algorithms to transform iterated integrals over root-valued alphabets into binomial sums. Using generating functions we study a few aspects of infinite (inverse) binomial sums.
Simplicity of condensed matter at its core: Generic definition of a Roskilde-simple system
Authors: Schrøder Thomas B. , Dyre Jeppe C.
Published: November 2014

The isomorph theory is reformulated by defining Roskilde-simple systems by the property that the order of the potential energies of configurations at one density is maintained when these are scaled uniformly to a different density. If the potential energy as a function of all particle coordinates is denoted by U(R), this requirement translates into U(Ra) < U(Rb) ⇒ U(λRa) < U(λRb). Isomorphs remain curves in the thermodynamic phase diagram along which structure, dynamics, and excess entropy are invariant, implying that the phase diagram is effectively one-dimensional with respect to many reduced-unit properties. In contrast to the original formulation of the isomorph theory, however, the density-scaling exponent is not exclusively a function of density and the isochoric heat capacity is not an exact isomorph invariant. A prediction is given for the latter quantity's variation along the isomorphs. Molecular dynamics simulations of the Lennard-Jones and Lennard-Jones Gaussian systems validate the new approach.
Controversial electronic structures and energies of Fe2, ${\rm Fe}_2^ +$ Fe 2+, and ${\rm Fe}_2^ -$ Fe 2− resolved by RASPT2 calculations
Authors: Hoyer Chad E. , Manni Giovanni Li , Truhlar Donald G. , Gagliardi Laura
Published: November 2014

The diatomic molecule Fe2 was investigated using restricted active space second-order perturbation theory (RASPT2). This molecule is very challenging to study computationally because predictions about the ground state and excited states depend sensitively on the choice of the quantum chemical method. For Fe2 we show that one needs to go beyond a full-valence active space in order to achieve even qualitative agreement with experiment for the dissociation energy, and we also obtain a smooth ground-state potential curve. In addition we report the first multireference study of ${\rm Fe}_2^ +$ Fe 2+, for which we predict an 8$\Sigma _u^ -$Σu− ground state, which was not predicted by previous computational studies. By using an active space large enough to remove the most serious deficiencies of previous theoretical work and by explicitly investigating the interpretations of previous experimental results, this study elucidates previous difficulties and provides – for the first time – a qualitatively correct treatment of Fe2, ${\rm Fe}_2^ +$ Fe 2+, and ${\rm Fe}_2^ -$ Fe 2−. Moreover, this study represents a record in terms of the number or active electrons and active orbitals in the active space, namely 16 electrons in 28 orbitals. Conventional CASPT2 calculations can be performed with at most 16 electrons in 16 orbitals. We were able to overcome this limit by using the RASPT2 formalism.
Reaction of the C3(X1Σg+) carbon cluster with H2S(X1A1), hydrogen sulfide: Photon-induced formation of C3S, tricarbon sulfur
Authors: Roehr Nathan P. , Szczepanski Jan , Fu Yi , Polfer Nicolas C. , Vala Martin
Published: November 2014

In this paper we report on the neutral-neutral reaction of the C3 carbon cluster with H2S in solid inert argon at 12 K, conditions that mimic, in part, the surfaces of interstellar grains. In the first step of the reaction, a C3•H2S complex is formed via an almost barrierless entrance addition mechanism. This complex, stabilized by an estimated 7.45 kJ/mol (CCSD(T)/aug-cc-pVTZ//B3LYP/6-311++G(d,p) level), is formed by the interaction of a terminal carbon of C3 with a hydrogen in H2S. This con-covalent complex displays a band at 2044.1 cm−1 observed via Fourier transform infrared absorption spectroscopy. With the help of the MP2/aug-ccpVDZ level method, this band is assigned to the CC asymmetric vibration mode. When the complex is exposed to UV-visible photons (hν < 5.5 eV) the tricarbon sulfur C3S molecule is identified, based on the appearance of a characteristic CC stretching band at 2047.5 cm−1. Calculated ground-state potential energy surfaces also confirm the concomitant formation of molecular H2. This facile reaction pathway involves an attainable transition state of 174.4 kJ/mol. Conversely, competing lower-energy reaction pathways that would lead to the generation of H2C3S (propadienethione), or C2H2 (acetylene) and CS, involve much more complex, multi-stage pathways, and are not observed experimentally.
The vibrational dependence of dissociative recombination: Rate constants for ${\rm N}_2^ +$N2+
Authors: Guberman Steven L.
Published: November 2014

Dissociative recombination rate constants are reported with electron temperature dependent uncertainties for the lowest 5 vibrational levels of the ${\rm N}_2^ +$N2+ ground state. The rate constants are determined from ab initio calculations of potential curves, electronic widths, quantum defects, and cross sections. At 100 K electron temperature, the rate constants overlap with the exception of the third vibrational level. At and above 300 K, the rate constants for excited vibrational levels are significantly smaller than that for the ground level. It is shown that any experimentally determined total rate constant at 300 K electron temperature that is smaller than 2.0 × 10−7 cm3/s is likely to be for ions that have a substantially excited vibrational population. Using the vibrational level specific rate constants, the total rate constant is in very good agreement with that for an excited vibrational distribution found in a storage ring experiment. It is also shown that a prior analysis of a laser induced fluorescence experiment is quantitatively flawed due to the need to account for reactions with unknown rate constants. Two prior calculations of the dissociative recombination rate constant are shown to be inconsistent with the cross sections upon which they are based. The rate constants calculated here contribute to the resolution of a 30 year old disagreement between modeled and observed ${\rm N}_2^ +$N2+ ionospheric densities.
The non-uniform early structural response of globular proteins to cold denaturing conditions: A case study with Yfh1
Authors: Chatterjee Prathit , Bagchi Sayan , Sengupta Neelanjana
Published: November 2014

The mechanism of cold denaturation in proteins is often incompletely understood due to limitations in accessing the denatured states at extremely low temperatures. Using atomistic molecular dynamics simulations, we have compared early (nanosecond timescale) structural and solvation properties of yeast frataxin (Yfh1) at its temperature of maximum stability, 292 K (Ts), and the experimentally observed temperature of complete unfolding, 268 K (Tc). Within the simulated timescales, discernible “global” level structural loss at Tc is correlated with a distinct increase in surface hydration. However, the hydration and the unfolding events do not occur uniformly over the entire protein surface, but are sensitive to local structural propensity and hydrophobicity. Calculated infrared absorption spectra in the amide-I region of the whole protein show a distinct red shift at Tc in comparison to Ts. Domain specific calculations of IR spectra indicate that the red shift primarily arises from the beta strands. This is commensurate with a marked increase in solvent accessible surface area per residue for the beta-sheets at Tc. Detailed analyses of structure and dynamics of hydration water around the hydrophobic residues of the beta-sheets show a more bulk water like behavior at Tc due to preferential disruption of the hydrophobic effects around these domains. Our results indicate that in this protein, the surface exposed beta-sheet domains are more susceptible to cold denaturing conditions, in qualitative agreement with solution NMR experimental results.
Self-consistent field theory of tethered polymers: One dimensional, three dimensional, strong stretching theories and the effects of excluded-volume-only interactions
Authors: Suo Tongchuan , Whitmore Mark D.
Published: November 2014

We examine end-tethered polymers in good solvents, using one- and three-dimensional self-consistent field theory, and strong stretching theories. We also discuss different tethering scenarios, namely, mobile tethers, fixed but random ones, and fixed but ordered ones, and the effects and important limitations of including only binary interactions (excluded volume terms). We find that there is a “mushroom” regime in which the layer thickness is independent of the tethering density, σ, for systems with ordered tethers, but we argue that there is no such plateau for mobile or disordered anchors, nor is there one in the 1D theory. In the other limit of brushes, all approaches predict that the layer thickness scales linearly with N. However, the σ1/3 scaling is a result of keeping only excluded volume interactions: when the full potential is included, the dependence is faster and more complicated than σ1/3. In fact, there does not appear to be any regime in which the layer thickness scales in the combination Nσ1/3. We also compare the results for two different solvents with each other, and with earlier Θ solvent results.
First principles study of metal contacts to monolayer black phosphorous
Authors: Chanana Anuja , Mahapatra Santanu
Published: November 2014

Atomically thin layered black phosphorous (BP) has recently appeared as an alternative to the transitional metal dichalcogenides for future channel material in a metal-oxide-semiconductor transistor due to its lower carrier effective mass. Investigation of the electronic property of source/drain contact involving metal and two-dimensional material is essential as it impacts the transistor performance. In this paper, we perform a systematic and rigorous study to evaluate the Ohmic nature of the side-contact formed by the monolayer BP (mBP) and metals (gold, titanium, and palladium), which are commonly used in experiments. Employing the Density Functional Theory, we analyse the potential barrier, charge transfer and atomic orbital overlap at the metal-mBP interface in an optimized structure to understand how efficiently carriers could be injected from metal contact to the mBP channel. Our analysis shows that gold forms a Schottky contact with a higher tunnel barrier at the interface in comparison to the titanium and palladium. mBP contact with palladium is found to be purely Ohmic, where as titanium contact demonstrates an intermediate behaviour.
Crossover in structure and dynamics of a primary alcohol induced by hydrogen-bonds dilution
Authors: Hennous Leila , Hamid Abdel Razzak Abdel , Lefort Ronan , Morineau Denis , Malfreyt Patrice , Ghoufi Aziz
Published: November 2014

Primary alcohols show a prominent Debye process in the dielectric relaxation located at a timescale longer than the main structural relaxation. Böhmer and co-workers studied dilution effects of the hydrogen bonding network of n-butanol (BuOH) with n-bromobutane (BuBr) to better understand the origin of this process. Interestingly, this work has evidenced a crossover in Debye relaxation time (τD) for a critical concentration in BuBr xc = 0.5. By using molecular dynamics simulations and NMR experiments we propose here to explore further dilution effects on the dipolar and translational dynamics. Moreover, we discuss the relation between structural and dynamical properties in the context of a detailed study of the microstructure and the H-bond network. The overall results are consistent with the existence of a topological change in the liquid structure occurring at about xc = 0.5 from a hypernetted percolating network to independent nanodomains of n-butanol molecules embedded in the n-bromobutane phase.
On the time scale associated with Monte Carlo simulations
Authors: Bal Kristof M. , Neyts Erik C.
Published: November 2014

Uniform-acceptance force-bias Monte Carlo (fbMC) methods have been shown to be a powerful technique to access longer timescales in atomistic simulations allowing, for example, phase transitions and growth. Recently, a new fbMC method, the time-stamped force-bias Monte Carlo (tfMC) method, was derived with inclusion of an estimated effective timescale; this timescale, however, does not seem able to explain some of the successes the method. In this contribution, we therefore explicitly quantify the effective timescale tfMC is able to access for a variety of systems, namely a simple single-particle, one-dimensional model system, the Lennard-Jones liquid, an adatom on the Cu(100) surface, a silicon crystal with point defects and a highly defected graphene sheet, in order to gain new insights into the mechanisms by which tfMC operates. It is found that considerable boosts, up to three orders of magnitude compared to molecular dynamics, can be achieved for solid state systems by lowering of the apparent activation barrier of occurring processes, while not requiring any system-specific input or modifications of the method. We furthermore address the pitfalls of using the method as a replacement or complement of molecular dynamics simulations, its ability to explicitly describe correct dynamics and reaction mechanisms, and the association of timescales to MC simulations in general.
A 1 kA-class cryogen-free critical current characterization system for superconducting coated conductors
Authors: Strickland N. M. , Hoffmann C. , Wimbush S. C.
Published: November 2014

A cryogenic electrical transport measurement system is described that is particularly designed to meet the requirements for routine and effective characterization of commercial second generation high-temperature superconducting (HTS) wires in the form of coated conductors based on YBa2Cu3O7. Specific design parameters include a base temperature of 20 K, an applied magnetic field capability of 8 T (provided by a HTS split-coil magnet), and a measurement current capacity approaching 1 kA. The system accommodates samples up to 12 mm in width (the widest conductor size presently commercially available) and 40 mm long, although this is not a limiting size. The sample is able to be rotated freely with respect to the magnetic field direction about an axis parallel to the current flow, producing field angle variations in the standard maximum Lorentz force configuration. The system is completely free of liquid cryogens for both sample cooling and magnet cool-down and operation. Software enables the system to conduct a full characterization of the temperature, magnetic field, and field angle dependence of the critical current of a sample without any user interaction. The system has successfully been used to measure a wide range of experimental and commercially-available superconducting wire samples sourced from different manufacturers across the full range of operating conditions. The system encapsulates significant advances in HTS magnet design and efficient cryogen-free cooling technologies together with the capability for routine and automated high-current electrical transport measurements at cryogenic temperatures. It will be of interest to both research scientists investigating superconductor behavior and commercial wire manufacturers seeking to accurately characterize the performance of their product under all desired operating conditions.
Electrical conductivity measurements of aqueous fluids under pressure with a hydrothermal diamond anvil cell
Authors: Ni Huaiwei , Chen Qi , Keppler Hans
Published: November 2014

Electrical conductivity data of aqueous fluids under pressure can be used to derive the dissociation constants of electrolytes, to assess the effect of ionic dissociation on mineral solubility, and to interpret magnetotelluric data of earth's interior where a free fluid phase is present. Due to limitation on the tensile strength of the alloy material of hydrothermal autoclaves, previous measurements of fluid conductivity were mostly restricted to less than 0.4 GPa and 800 °C. By adapting a Bassett-type hydrothermal diamond anvil cell, we have developed a new method for acquiring electrical conductivity of aqueous fluids under pressure. Our preliminary results for KCl solutions using the new method are consistent with literature data acquired with the conventional method, but the new method has great potential for working in a much broader pressure range.
A model for the linear stability of the interface between aqueous humor and vitreous substitutes after vitreoretinal surgery
Authors: Isakova Krystyna , Pralits Jan O. , Repetto Rodolfo , Romano Mario R.
Published: November 2014

We consider the motion of two immiscible viscous fluids induced by periodic oscillations of a flat solid surface along its plane. The interface between the two fluids is parallel to the solid wall; one fluid occupies the region between the wall and the interface and the other extends from the interface to infinity. We study numerically the linear stability of the interface with respect to two-dimensional perturbations using the normal mode analysis and assuming quasi-steady flow conditions. The analysis is motivated by the need of understanding the behavior of vitreous substitutes inserted in the vitreous chamber of the eye after vitrectomy. This is a common surgical procedure adopted to treat retinal detachments, whereby the vitreous humor is removed from the eye and replaced by fluids immiscible with water. Owing to their hydrophobic nature, vitreous substitutes coexist in the vitreous chamber with a certain amount of aqueous humor (the fluid produced in the anterior part of the eye) and, typically, a thin layer of aqueous separates the tamponade fluid from the retina. A common problem with this treatment is that, in some cases, the interface between the two fluids breaks down and this might eventually lead to the generation of an emulsion. It is believed that mechanics plays an important role in this process but the problem remains very poorly understood. We find that instability of the interface is possible in a range of parameters that is relevant for the problem that motivated the present analysis. This suggests that shear instability is likely a possible mechanism triggering the onset of vitreous substitutes–aqueous interface instability.
Lateral migration of a microdroplet under optical forces in a uniform flow
Authors: Cho Hyunjun , Chang Cheong Bong , Jung Jin Ho , Sung Hyung Jin
Published: November 2014

The behavior of a microdroplet in a uniform flow and subjected to a vertical optical force applied by a loosely focused Gaussian laser beam was studied numerically. The lattice Boltzmann method was applied to obtain the two-phase flow field, and the dynamic ray tracing method was adopted to calculate the optical force. The optical forces acting on the spherical droplets agreed well with the analytical values. The numerically predicted droplet migration distances agreed well with the experimentally obtained values. Simulations of the various flow and optical parameters showed that the droplet migration distance nondimensionalized by the droplet radius is proportional to the S number (zd/rp = 0.377S), which is the ratio of the optical force to the viscous drag. The effect of the surface tension was also examined. These results indicated that the surface tension influenced the droplet migration distance to a lesser degree than the flow and optical parameters. The results of the present work hold for the refractive indices of the mean fluid and the droplet being 1.33 and 1.59, respectively.