bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface-Enhanced Raman Scattering with Nanomaterials
Authors: Umadevi M. , Milton Franklin Benial A.
Published: November 2016

Surface-enhanced Raman scattering (SERS) is a powerful analytical technique that enhances the Raman scattering signal from molecules adsorbed on or in close proximity to the metal surface. It is possible owing to localized surface plasmon resonance occurring in nanostructures metal surfaces. There are two commonly considered mechanisms for SERS, electromagnetic and chemical enhancement. The electromagnetic theory emphasizes that the Raman enhancements for adsorbates on particular surfaces occur because of the enhancement in electric field provided by the surface. When the incident light strikes the surfaces, surface plasmons can be excited by radiation, resulting in enhanced electromagnetic fields close to the surface. The chemical theory is thought to involve the creation of new electronic states and the formation of charge transfer complexes in some special cases between the chemisorbed species and the SERS active substrates, resulting in an enhanced Raman cross section of the molecules. This chapter describes the SERS activities of quinone derivatives by plasmonic silver nanoparticles and pollutant detection using gold nanoparticles. SERS studies of 2-bromo-1,4-naphthoquinone and 2,3-dibromo-1,4-naphthoquinone on prepared nanoparticles are described. SERS analysis of polluted soil is also discussed. The orientation of the above molecules on silver nanoparticles was elucidated from the spectral analysis
Microfluidic technologies in cell isolation and analysis for biomedical applications
Authors: Wu Jing , Chen Qiushui , Lin Jin-Ming
Published: November 2016

Microfluidic cell isolation and its applications in the biomedical field have been reviewed.
A benzoxazole functionalized fluorescent probe for selective Fe3+ detection and intracellular imaging in living cells
Authors: Yang Zheng , Bai Xinxin , Ma Siyue , Liu Xiangrong , Zhao Shunsheng , Yang Zaiwen
Published: November 2016

A rhodamine based 2-aminobenzoxazole functionalized probe was presented for reversible detection of Fe3+.
Metastable hydrogels from aromatic dipeptides
Authors: Conte M. P. , Singh N. , Sasselli I. R. , Escuder B. , Ulijn R. V.
Published: November 2016

The dipeptides FF and FF-NH2 form metastable hydrogels upon sonication. The hydrogels show instantaneous syneresis upon mechanical contact.
Highly sensitive and selective miRNA detection based on a closed ring probe and multiple signal amplification
Authors: Tang Yaqin , He Xiao , Zhou Zhenxia , Tang Jiakun , Guo Rong , Feng Xuli
Published: November 2016

A highly sensitive and selective miRNA detection approach based on a small circular probe and dual signal amplification has been reported.
In situ phase behaviour of a high capacity LiCoPO4 electrode during constant or pulsed charge of a lithium cell
Authors: Palmer Michael G. , Frith James T. , Hector Andrew L. , Lodge Andrew W. , Owen John R. , Nicklin Chris , Rawle Jonathan
Published: November 2016

The phase changes that occur during lithium extraction from LiCoPO4 under constant or pulsed current were studied using synchrotron X-ray diffraction.
Understanding the role of hydrogen bonding in Brønsted acidic ionic liquid-catalyzed transesterification: a combined theoretical and experimental investigation
Authors: Li Kaixin , Yan Yibo , Zhao Jun , Lei Junxi , Jia Xinli , Mushrif Samir H. , Yang Yanhui
Published: November 2016

The intra- and inter-hydrogen bonding networks that govern the catalytic activity of Brønsted acidic ionic liquids were identified.
Modeling the archetype cysteine protease reaction using dispersion corrected density functional methods in ONIOM-type hybrid QM/MM calculations; the proteolytic reaction of papain
Authors: Fekete Attila , Komáromi István
Published: November 2016

A proteolytic reaction of papain with a simple peptide model substrateN-methylacetamide has been studied.
Chemical vapor deposition-prepared sub-nanometer Zr clusters on Pd surfaces: promotion of methane dry reforming
Authors: Mayr Lukas , Shi Xue-Rong , Köpfle Norbert , Milligan Cory A. , Zemlyanov Dmitry Y. , Knop-Gericke Axel , Hävecker Michael , Klötzer Bernhard , Penner Simon
Published: November 2016

An inverse Pd–Zr model catalyst was prepared by chemical vapor deposition (CVD) using zirconium-t-butoxide (ZTB) as an organometallic precursor.
Modification of silica-supported tungsten neosilyl oxo precatalysts: impact of substituted phenol on activity and stability in olefin metathesis
Authors: Bouhoute Y. , Del Rosal I. , Szeto K. C. , Merle N. , Grekov D. , De Mallmann A. , Le Roux E. , Delevoye L. , Gauvin R. M. , Maron L. , Taoufik M.
Published: November 2016

Development of a novel and convenient strategy to access a large variety of highly active tungsten oxo olefin metathesis pre-catalysts.
High-valent cationic metal–organic macrocycles as novel supports for immobilization and enhancement of activity of polyoxometalate catalysts
Authors: Duan Yunpeng , Wei Wei , Xiao Fei , Xi Yaru , Chen Shi-Lu , Wang Jin-Liang , Xu Yanqing , Hu Changwen
Published: November 2016

Developing a new strategy for preparing highly active and recyclable heterogeneous polyoxometalate (POM) catalysts has attracted much attention in the past decades.
On-chip electromagnetic tweezers – 3-dimensional particle actuation using microwire crossbar arrays
Authors: Rinklin Philipp , Krause Hans-Joachim , Wolfrum Bernhard
Published: November 2016

We use microwire crossbar arrays that combine magnetophoretic and dielectrophoretic forces for three-dimensional particle actuation.
Transition-metal-free synthesis of indole-fused dibenzo[b,f][1,4]oxazepines via Smiles rearrangement
Authors: Hu Fangdong , Liu Huanhuan , Jia Jiong , Ma Chen
Published: November 2016

A one-pot transition-metal-free approach for the synthesis of indole-fused dibenzo[b,f][1,4]oxazepines from 2-(1H-indol-2-yl)phenol and 1,2-dihalobenzenes or 2 halonitroarenes has been developed.
Cobalt-promoted selective arylation of benzamides and acrylamides with arylboronic acids
Authors: Hu Liang , Gui Qingwen , Chen Xiang , Tan Ze , Zhu Gangguo
Published: November 2016

A novel cobalt-promoted arylation of aryl C–H bonds with arylboronic acids has been realized by using 8-aminoquinoline as the directing group. A notable feature of this newly developed protocol is that acrylamides, which cannot be arylated using copper salts as the promoter, can also be efficiently arylated.
Stereoselective copolymerization of amino-functionalized styrene with butadiene using a half-sandwich scandium complex
Authors: Shi Zhenghai , Guo Fang , Meng Rui , Jiang Lei , Li Yang
Published: November 2016

Stereoselective copolymerization of amino-functionalized styrene with butadiene was conducted and the influence of amino groups on the copolymerization performance was investigated.
Transition-metal-free controlled polymerization of 2-polyfluorophenyl-5-trimethylsilylthiophenes: the substituent impact of fluorine
Authors: Sanji Takanobu , Nose Keiji , Kakinuma Junko , Iyoda Tomokazu
Published: November 2016

A transition-metal-free polymerization of a series of 2-polyfluorophenyl-5-trimethylsilylthiophenes promoted by fluoride anions is reported.
Identification and genotoxicity evaluation of two carbamate impurities in rasagiline
Authors: Sun Yongqiang , Zhang Xinyu , Yan Yimin , Tu Yongrui , Feng Xiaohui , Jiang Wei , Zheng Feng
Published: November 2016

During the synthesis of a second-generation monoamine oxidase-B inhibitor rasagiline, two unknown impurities (impurity A and impurity B) were detected and isolated by preparative liquid chromatography.
Effect of guests on the adsorption interaction between a hydrate cage and guests
Authors: Liu Chanjuan , Zhang Zhengcai , Guo Guang-Jun
Published: November 2016

A criterion is proposed to judge which guest can enter the cage through which face.
Thickness-dependent bandgap tunable molybdenum disulfide films for optoelectronics
Authors: Zhu Juntong , Wu Jiang , Sun Yinghui , Huang Jianwen , Xia Yufei , Wang Hao , Wang Haibo , Wang Yun , Yi Qinghua , Zou Guifu
Published: November 2016

Thickness-controlled uniform MoS2 films are grown by polymer-assisted deposition approach from 50 nm to 2.5 nm, corresponding to bandgaps modulated from 1.50 eV to 1.64 eV. The photoresponse test demonstrates as-grown MoS2 has fast response to light.
Polystyrene controlled growth of zerovalent nanoiron/magnetite on a sponge-like carbon matrix towards effective Cr(vi) removal from polluted water
Authors: Gu Hongbo , Lou Han , Ling Dong , Xiang Bo , Guo Zhanhu
Published: November 2016

Epoxide functionalized polystyrene controlled growth of zerovalent nanoiron/magnetite on a sponge-like carbon matrix (nZVI/Fe3O4@C) nanocomposites show a unique Cr(vi) removal performance over a wide pH range.
Synthesis of bimetallic Zr(Ti)-naphthalendicarboxylate MOFs and their properties as Lewis acid catalysis
Authors: Rasero-Almansa Antonia M. , Iglesias Marta , Sánchez Félix
Published: November 2016

Bimetallic Zr(Ti)-NDC based metal–organic frameworks (MOFs) have been prepared by incorporation of titanium(iv) into zirconium(iv)-NDC-MOFs (UiO family).
Manganese dioxide-core–shell hyperbranched chitosan (MnO2–HBCs) nano-structured screen printed electrode for enzymatic glucose biosensors
Authors: Abd El-Haleem Hala S. , Hefnawy Amr , Hassan Rabeay Y. A. , Badawi Ashraf H. , El-Sherbiny Ibrahim M.
Published: November 2016

In this study, the synthesis, characterization and testing of new polymeric–metal oxide nanocomposites for enzymatic glucose biosensors were performed.
Durable gels with ultra-low adhesion to ice
Authors: Beemer Darryl L. , Wang Wei , Kota Arun K.
Published: November 2016

Building on principles of adhesion mechanics, we developed novel PDMS gels with ultra-low adhesion to ice and outstanding mechanical durability.
Ultra-thin nanosheet assemblies of graphitic carbon nitride for enhanced photocatalytic CO2 reduction
Authors: Xia Pengfei , Zhu Bicheng , Yu Jiaguo , Cao Shaowen , Jaroniec Mietek
Published: November 2016

This work demonstrates the development of hierarchical ultra-thin g-C3N4 nanosheets with enhanced photocatalytic CO2 reduction activity.
Transition metal dissolution and deposition in Li-ion batteries investigated by operando X-ray absorption spectroscopy
Authors: Wandt Johannes , Freiberg Anna , Thomas Rowena , Gorlin Yelena , Siebel Armin , Jung Roland , Gasteiger Hubert A. , Tromp Moniek
Published: November 2016

Operando X-ray absorption spectroscopy studies of transition metal dissolution in Li-ion batteries.
Polymeric nanoparticles for colon cancer therapy: overview and perspectives
Authors: You Xinru , Kang Yang , Hollett Geoffrey , Chen Xing , Zhao Wei , Gu Zhipeng , Wu Jun
Published: November 2016

Colorectal cancer (CRC) is the third-most common malignant tumour and is associated with high morbidity and mortality worldwide.
A light and reduction dual sensitive supramolecular self-assembly gene delivery system based on poly(cyclodextrin) and disulfide-containing azobenzene-terminated branched polycations
Authors: Jiang Qimin , Zhang Yunti , Zhuo Renxi , Jiang Xulin
Published: November 2016

Light and reduction sensitive supramolecular host–guest gene vectors can regulate gene release upon exposure to reduction environments and light radiation inside cells.
Platinum nanoparticles inhibit antioxidant effects of vitamin C via ascorbate oxidase-mimetic activity
Authors: Chen Chao , Fan Sanhong , Li Chen , Chong Yu , Tian Xin , Zheng Jiwen , Fu Peter P. , Jiang Xiumei , Wamer Wayne G. , Yin Jun-jie
Published: November 2016

Pt nanoparticles with ascorbate oxidase-mimetic activity inhibit the cytoprotective effect of vitamin C on cells challenged by H2O2.
Nanopapers of layer-by-layer nanotubes
Authors: Zhang Shouwei , Vlémincq Céline , Ramirez Wong Diana , Magnin Delphine , Glinel Karine , Demoustier-Champagne Sophie , Jonas Alain M.
Published: November 2016

A straightforward filtration methodology of templated layer-by-layer (LbL) nanotubes leads to new multifunctional nanopapers over centimeter square surfaces.
Highly efficient digital quadrature transmitter with dual VDD and dynamic cell selection
Authors: Jin H. , Moon K. , Lee S. , Kim B.
Published: November 2016

A digital quadrature dual VDD transmitter with a switched capacitor power combiner is presented. To improve the efficiency, the cell in the transmitter is dynamically selected to minimise the voltage across the capacitors, thereby minimising the discharging loss. The chip is fabricated in 28‐nm CMOS process. The implemented transmitter has a peak power of 17.2 dBm with a PAE of 37.4% at 880 MHz. The average power is 7.9 dBm with a PAE of 23.6% under ACLR of −32 dBc using a 10 MHz, 16 QAM, and 6.9 dB LTE signal.
Hybrid approach for planning and operating active distribution grids
Authors: Karagiannopoulos Stavros , Aristidou Petros , Hug Gabriela
Published: November 2016

This paper investigates the planning and operational processes of modern distribution networks hosting distributed energy resources (DERs). While in the past the two aspects have been distinct, a methodology is proposed in this paper to co‐optimise the two phases by considering the operational flexibility offered by DERs already in the planning phase. By employing AC optimal power flow (OPF) to analyse the worst‐case scenarios for the load and distributed generator injection, the optimal set‐points for the DERs are determined such that the network's security is ensured. From these results, the optimised individual characteristic curves are then extracted for each DER which are used in the operational phase for the local control of the devices. The optimised controls use only local measurements to address system‐wide issues and emulate the OPF solution without any communication. Finally, the proposed methodology is tested on the Cigre LV benchmark grid confirming that it is successful in mitigating with acceptable violations over‐ and under‐voltage problems, as well as congestion issues. Its performance is compared against the OPF‐based approach and currently employed local control schemes.
Analogous elastic network for the analysis of power system energy structure
Authors: Cai Guowei , Sun Z.L. , Yang Deyou , Wang Y.W.
Published: November 2016

A new approach to the analysis of the transient energy interaction in power systems is presented in this work on the basis of an analogous elastic network. A power system is first rigorously mapped to an elastic network consisting of elastic branches with different elasticity coefficients. On the basis of elasticity mechanics and the analogous elastic network, the transient energy of the different parts, such as the synchronous generators, branches, and loads, is defined and has been proved to agree with the law of energy conservation. Subsequently, based on the law of energy conservation and energy feature analysis, the concept of the power system energy structure (PSES) is built to exhibit the distribution and interaction of transient energy in the power system. Wide area and local area transient energy interaction can be analysed using the measurement‐based energy structure, which shows obvious potential in on‐line monitoring and analysis of power system oscillation. Finally, the simulations of Western Systems Coordinating Council (WSCC) three‐generator test system and a practical power system are performed and analysed to verify the rationality of the analogous elastic network and the validity of the proposed PSES.
Synchronisation and anti‐synchronisation of chaotic systems with application to DC–DC boost converter
Authors: Sakthivel Rathinasamy , Santra Srimanta , Marshal Anthoni Selvaraj , Kuppili Venkatanareshbabu
Published: November 2016

This study addresses the design of sampled‐data feedback L∞ controller for synchronisation of chaotic systems with external disturbances. By employing a novel time‐dependent Lyapunov function which is positive definite at sampling times but not necessary between the sampling times, a new set of sufficient conditions in terms of linear matrix inequality is derived to a design sampled‐data L∞ control for synchronisation. More precisely, the proposed synchronisation results depend on both the lower and upper bounds on sampling interval and also the available information of the actual sampling pattern is fully used. Further, based on the Lyapunov function, an asymptotic anti‐synchronisation criterion is derived by analysing the corresponding anti‐synchronisation error systems. Subsequently, a set of sampled‐data synchronisation control is designed in terms of solution to certain matrix inequalities that can be solved effectively by using available software. Finally, a numerical example based on boost converter DC–DC model is employed to show the effectiveness of the proposed sampled‐data L∞ synchronisation and anti‐synchronisation control scheme.
Modified bio‐inspired optimisation algorithm with a centroid decision making approach for solving a multi‐objective optimal power flow problem
Authors: Barocio Emilio , Regalado Jose , Cuevas Erick , Uribe Felipe , Zúñiga Pavel , Torres Pedro J. Ramirez
Published: November 2016

A method to solve a multi‐objective optimal power flow (MOOPF) problem with multiple and competing objective functions (OF) is presented. The modified flower pollination algorithm and the normal boundary intersection method are used in a complementary way to determine the Pareto front solution of the MOOPF problem. To help in the decision making process, an intuitive criterion based on the centroid concept is proposed to select the best compromise solution from the Pareto frontier. To demonstrate the capabilities of the proposed method, different OFs are combined to calculate the Pareto front solution on the IEEE 30 bus test system. Finally, a comparison of the proposed centroid based method against the well‐known fuzzy membership and entropy criterions is provided in the results section.
Method of local characteristics for calculating electric field and ion current of HVDC transmission lines with transverse wind
Authors: Qiao Ji , Zou Jun , Yuan Jiansheng , Lee Jaebok , Ju Mun‐no
Published: November 2016

The electric field and ion flow are significantly influenced by the transverse wind around the high‐voltage direct current (HVDC) transmission lines. In this study, a new method using local characteristics is proposed to analyse the effect of wind. The present method, called method of local characteristic, updates the ion density based on the local characteristic curve in each second‐order finite element method (FEM) element without Deutsch assumption. The defining equation of the characteristics is able to take into account the directional character of the information propagation in convective transport and has a better performance to satisfy the conservation law. The present approach is stable and efficient even in the presence of high‐speed transverse wind. Calculations show good agreement with the measurement values of the reduced‐scale unipolar model and the full‐scale bipolar test line. Finally, the influence of wind on the electric field and ion current is discussed.
Three‐input majority gate using spatially localised DNA hairpins
Authors: George Aby K. , Singh Harpreet
Published: November 2016

DNA circuits employing DNA strand displacement technique are considered as a possible replacement for silicon‐based circuits, especially in implantable medical devices, because of its compatibility with bio‐signals, smaller size, and light weight. In this work, a new DNA strand displacement based, three‐input spatially localised majority gate using DNA hairpins is proposed. The DNA hairpins used in this majority gate are tethered to an Origami substrate, and hence, the DNA hairpins are spatially separated from each other. The localisation helps the designer to reuse the strands, without causing any spurious reactions. It is believed currently that no design is available in the literature for a localised DNA majority gate. The visual DSD software is used for simulating the proposed majority gate.
CT, Ultraschall & Co.: Tausch mich!
Authors: Rößing Sabine
Published: November 2016

Der Auslandsmarkt für medizintechnische Geräte boomt. In Deutschland gibt es dagegen wenige Neuinstallationen. Grund ist der Investitionsstau. Das Geschäft machen die Hersteller hierzulande vor allem mit dem Austausch bereits installierter Geräte.
Calculations of electric dipole moments and static dipole polarizabilities based on the two-component normalized elimination of the small component method
Authors: Yoshizawa Terutaka , Zou Wenli , Cremer Dieter
Published: November 2016

The analytical energy gradient and Hessian of the two-component Normalized Elimination of the Small Component (2c-NESC) method with regard to the components of the electric field are derived and used to calculate spin-orbit coupling (SOC) corrected dipole moments and dipole polarizabilities of molecules, which contain elements with high atomic number. Calculated 2c-NESC dipole moments and isotropic polarizabilities agree well with the corresponding four-component-Dirac Hartree–Fock or density functional theory values. SOC corrections for the electrical properties are in general small, but become relevant for the accurate prediction of these properties when the molecules in question contain sixth and/or seventh period elements (e.g., the SO effect for At2 is about 10% of the 2c-NESC polarizability). The 2c-NESC changes in the electric molecular properties are rationalized in terms of spin-orbit splitting and SOC-induced mixing of frontier orbitals with the same j = l + s quantum numbers.
Electronic friction near metal surfaces: A case where molecule-metal couplings depend on nuclear coordinates
Authors: Dou Wenjie , Subotnik Joseph E.
Published: November 2016

We derive an explicit form for the electronic friction as felt by a molecule near a metal surface for the general case that molecule-metal couplings depend on nuclear coordinates. Our work generalizes a previous study by von Oppen et al. [Beilstein J. Nanotechnol. 3, 144 (2012)], where we now go beyond the Condon approximation (i.e., molecule-metal couplings are not held constant). Using a non-equilibrium Green’s function formalism in the adiabatic limit, we show that fluctuating metal-molecule couplings lead to new frictional damping terms and random forces, plus a correction to the potential of mean force. Numerical tests are performed and compared with a modified classical master equation; our results indicate that violating the Condon approximation can have a large effect on dynamics.
Richtmyer-Meshkov unstable dynamics influenced by pressure fluctuations
Authors: Bhowmick A. K. , Abarzhi S. I.
Published: November 2016

We theoretically study the effect of pressure fluctuations on the Richtmyer-Meshkov (RM) unstable interface in approximation of ideal incompressible immiscible fluids and two-dimensional flow. Pressure fluctuations are treated as an effective acceleration directed from the heavy to light fluid with inverse square time dependence. The group theory approach is applied to analyze large-scale coherent dynamics, solve the complete set of the governing equations, and find regular asymptotic solutions describing RM bubbles. A strong effect is found, for the first time to our knowledge, of pressure fluctuations on the interface morphology and dynamics. In the linear regime, a nearly flat bubble gets more curved, and its velocity increases for strong pressure fluctuations and decreases otherwise. In the nonlinear regime, solutions form a one-parameter family parameterized by the bubble front curvature. For the fastest stable solution in the family, the RM bubble is curved for strong pressure fluctuations and is flattened otherwise. The flow is characterized by the intense motion of the fluids in the vicinity of the interface, effectively no motion away from the interface, and presence of shear at the interface leading to formation of smaller scale vortical structures. Our theoretical results agree with and explain existing experiments and simulations and identify new qualitative and quantitative characteristics to evaluate the strength of pressure fluctuations in experiments and simulations.
Aspect ratio effect on particle transport in turbulent duct flows
Authors: Noorani A. , Vinuesa R. , Brandt L. , Schlatter P.
Published: November 2016

The dynamics of dilute micron-sized spherical inertial particles in turbulent duct flows is studied by means of direct numerical simulations of the carrier phase turbulence with one-way coupled Lagrangian particles. The geometries are a square and a rectangular duct with width-to-height aspect ratio AR of 3 operating at Reτ,c = 360 (based on the centerplane friction velocity and duct half-height). The present study is designed to determine the effect of turbulence-driven secondary motion on the particle dynamics. Our results show that a weak cross-flow secondary motion significantly changes the cross-sectional map of the particle concentration, mean velocity, and fluctuations. As the geometry of the duct is widened from AR = 1 to 3, the secondary vortex on the horizontal wall significantly expands in the spanwise direction, and although the kinetic energy of the secondary flow increases close to the corner, it decays towards the duct centreplane in the AR = 3 case so as the turbulent carrier phase approaches the behavior in spanwise-periodic channel flows, a fact that significantly affects the particle statistics. In the square duct the particle concentration in the viscous sublayer is maximum at the duct centreplane, whereas the maximum is found closer to the corner, at a distance of |z/h| ≈ 1.25 from the centreplane, in the AR = 3 case. Interestingly the centreplane concentration in the rectangular duct is around 3 times lower than that in the square duct. Moreover, a second peak in the accumulation distribution is found right at the corners for both ducts. At this location the concentration increases with particle inertia. The secondary motion changes also the cross-stream map of the particle velocities significantly in comparison to the fluid flow statistics. These directly affect the particle velocity fluctuations such that multiple peaks appear near the duct walls for the particle streamwise and wall-normal velocity fluctuations.
Perspective: Two-dimensional resonance Raman spectroscopy
Authors: Molesky Brian P. , Guo Zhenkun , Cheshire Thomas P. , Moran Andrew M.
Published: November 2016

Two-dimensional resonance Raman (2DRR) spectroscopy has been developed for studies of photochemical reaction mechanisms and structural heterogeneity in complex systems. The 2DRR method can leverage electronic resonance enhancement to selectively probe chromophores embedded in complex environments (e.g., a cofactor in a protein). In addition, correlations between the two dimensions of the 2DRR spectrum reveal information that is not available in traditional Raman techniques. For example, distributions of reactant and product geometries can be correlated in systems that undergo chemical reactions on the femtosecond time scale. Structural heterogeneity in an ensemble may also be reflected in the 2D spectroscopic line shapes of both reactive and non-reactive systems. In this perspective article, these capabilities of 2DRR spectroscopy are discussed in the context of recent applications to the photodissociation reactions of triiodide and myoglobin. We also address key differences between the signal generation mechanisms for 2DRR and off-resonant 2D Raman spectroscopies. Most notably, it has been shown that these two techniques are subject to a tradeoff between sensitivity to anharmonicity and susceptibility to artifacts. Overall, recent experimental developments and applications of the 2DRR method suggest great potential for the future of the technique.
Symmetry analysis of Raman scattering mediated by neighboring molecules
Authors: Williams Mathew D. , Bradshaw David S. , Andrews David L.
Published: November 2016

Raman spectroscopy is a key technique for the identification and structural interrogation of molecules. It generally exploits changes in vibrational state within individual molecules which produce, in the scattered light, frequencies that are absent in the incident light. Considered as a quantum optical process, each Raman scattering event involves the concurrent annihilation and creation of photons of two differing radiation modes, accompanying vibrational excitation or decay. For molecules of sufficiently high symmetry, certain transitions may be forbidden by the two-photon selection rules, such that corresponding frequency shifts may not appear in the scattered light. By further developing the theory on a formal basis detailed in other recent work [M. D. Williams et al., J. Chem. Phys. 144, 174304 (2016)], the present analysis now addresses cases in which expected selection rule limitations are removed as a result of the electronic interactions between neighboring molecules. In consequence, new vibrational lines may appear—even some odd parity (ungerade) vibrations may then participate in the Raman process. Subtle differences arise according to whether the input and output photon events occur at either the same or different molecules, mediated by intermolecular interactions. For closely neighboring molecules, within near-field displacement distances, it emerges that the radiant intensity of Raman scattering can have various inverse-power dependences on separation distance. A focus is given here to the newly permitted symmetries, and the results include an extended list of irreducible representations for each point group in which such behavior can arise.
Sequential bonding of CO molecules to a titanium dimer: A photoelectron velocity-map imaging spectroscopic and theoretical study of Ti2(CO)n− (n = 1-9)
Authors: Zou Jinghan , Xie Hua , Dai Dongxu , Tang Zichao , Jiang Ling
Published: November 2016

Binuclear titanium carbonyl cluster anions, Ti2(CO)n− (n = 4-6), are produced via a laser vaporization supersonic cluster source and characterized by mass-selected photoelectron velocity-map imaging spectroscopy. Quantum chemical calculations are carried out for Ti2(CO)n− (n = 1-9) to explore the trend of sequential bonding of CO molecules to a titanium dimer. It has been found that the CO molecules bind to Ti2 in a side-on fashion and form a stable Ti2[η2(μ2-C, O)]3 structure at n = 3, the motif of which retains up to n = 5. Starting at n = 6, a new building block of two CO groups side-on-bonded to Ti2 is favored, the structure of which persists up to n = 9. In the larger clusters (n = 6-9), the side-on-bonded CO molecule can be stabilized via the removal of two electrons from an anionic titanium carbonyl, which is different from the effect of charge on CO binding in rhodium carbonyls where bridge-bonded CO molecules are selectively destabilized by the removal of an electron from a neutral rhodium carbonyl. The present study provides a stepwise picture for molecular-level understanding of CO bonding on transition-metal clusters, which is directly relevant to the elementary processes of CO at metal catalysts.
A compact and versatile dynamic flow cryostat for photon science
Authors: van der Linden Peter J. E. M. , Moretti Sala Marco , Henriquet Christian , Rossi Matteo , Ohgushi Kenya , Fauth François , Simonelli Laura , Marini Carlo , Fraga Edmundo , Murray Claire , Potter Jonathan , Krisch Michael
Published: November 2016

We have developed a helium gas flow cryostat for use on synchrotron tender to hard X-ray beamlines. Very efficient sample cooling is achieved because the sample is placed directly in the cooling helium flow on a removable sample holder. The cryostat is compact and easy to operate; samples can be changed in less than 5 min at any temperature. The cryostat has a temperature range of 2.5–325 K with temperature stability better than 0.1 K. The very wide optical angle and the ability to operate in any orientation mean that the cryostat can easily be adapted for different X-ray techniques. It is already in use on different beamlines at the European Synchrotron Radiation Facility (ESRF), ALBA Synchrotron Light Facility (ALBA), and Diamond Light Source (DLS) for inelastic X-ray scattering, powder diffraction, and X-ray absorption spectroscopy. Results obtained at these beamlines are presented here.
Why does MP2 work?
Authors: Fink Reinhold F.
Published: November 2016

We show analytically and numerically that the performance of second order Møller-Plesset (MP) perturbation theory (PT), coupled-cluster (CC) theory, and other perturbation theory approaches can be rationalized by analyzing the wavefunctions of these methods. While rather large deviations for the individual contributions of configurations to the electron correlation energy are found for MP wavefunctions, they profit from an advantageous and robust error cancellation: The absolute contribution to the correlation energy is generally underestimated for the critical excitations with small energy denominators and all other doubly excited configurations where the two excited electrons are coupled to a singlet. This is balanced by an overestimation of the contribution of triplet-coupled double excitations to the correlation energy. The even better performance of spin-component-scaled-MP2 theory is explained by a similar error compensation effect. The wavefunction analysis for the lowest singlet states of H2O, CH2, CO, and Cu+ shows the predicted trends for MP methods, rapid but biased convergence of CC theory as well as the substantial potential of linearized CC, or retaining the excitation-degree (RE)-PT.
Evaluation of effects of pH and ionic strength on colloidal stability of IgG solutions by PEG-induced liquid-liquid phase separation
Authors: Thompson Ronald W. , Latypov Ramil F. , Wang Ying , Lomakin Aleksey , Meyer Julie A. , Vunnum Suresh , Benedek George B.
Published: November 2016

Colloidal stability of IgG antibody solutions is important for pharmaceutical and medicinal applications. Solution pH and ionic strength are two key factors that affect the colloidal stability of protein solutions. In this work, we use a method based on the PEG-induced liquid-liquid phase separation to examine the effects of pH and ionic strength on the colloidal stability of IgG solutions. We found that at high ionic strength (≥0.25M), the colloidal stability of most of our IgGs is insensitive to pH, and at low ionic strength (≤0.15M), all IgG solutions are much more stable at pH 5 than at pH 7. In addition, the PEG-induced depletion force is less efficient in causing phase separation at pH 5 than at pH 7. In contrast to the native inter-protein interaction of IgGs, the effect of depletion force on phase separation of the antibody solutions is insensitive to ionic strength. Our results suggest that the long-range electrostatic inter-protein repulsion at low ionic strength stabilizes the IgG solutions at low pH. At high ionic strength, the short-range electrostatic interactions do not make a significant contribution to the colloidal stability for most IgGs with a few exceptions. The weaker effect of depletion force at lower pH indicates a reduction of protein concentration in the condensed phase. This work advances our basic understanding of the colloidal stability of IgG solutions and also introduces a practical approach to measuring protein colloidal stability under various solution conditions.
Weakly nonlinear instabilities of a liquid ring
Authors: Zhao Sicheng , Tao Jianjun
Published: November 2016

The weakly nonlinear instability of a liquid ring is investigated by perturbation method and illustrates several important features at the early stage of evolution after destabilization. When the centerline maintains circular, the ring would transform into a droplet chain during its shrinkage, but tends to possess some local pinching during the expansion. If there is an additional distortion of the centerline, an evident tendency to protrude spikes, on each of which a droplet may be formed, is predicted. The analysis concentrates on inviscid cases, because the viscosity of ring liquid is proven to merely affect the base state. Besides, the interaction between instability modes is studied to understand the irregularity of perturbed surface and centerline, and the four locations where the irregularity appears to the maximum extent are discovered. All these results are confirmed by numerical simulations of the same model and experimental observations on ring-shaped the rim of drop-splash ejecta, and hence are related intrinsically with the spike formation process.
Self-propelled flexible fin in the wake of a circular cylinder
Authors: Park Sung Goon , Kim Boyoung , Sung Hyung Jin
Published: November 2016

The behavior of a self-propelled flexible fin behind a circular cylinder in a uniform flow was explored using the immersed boundary method. The transverse heaving motion of the leading edge of the fin was prescribed, whereas the lateral behavior was spontaneously determined by the hydrodynamic interactions between the fin and the fluid environment. Three different behaviors were observed: propulsion upstream, drift downstream, and holding stationary at an equilibrium position. In a uniform flow, the fin could not overcome the positive net drag, and it drifted downstream. By contrast, a fin in the wake of a cylinder was propelled toward the circular cylinder during the heaving motion. The trailing edge of the fin passively fluttered along the oncoming vortices, thereby propelling the fin upstream. During the upstream propulsion behavior, the fin was propelled through the vortex cores. The fin was observed to remain stationary at a heaving frequency equal to the vortex shedding frequency, and a slaloming behavior was observed between the oncoming vortical structures. The fin was not propelled toward the cylinder during the slaloming behavior; rather, it lingered at a certain streamwise distance from the cylinder. Several equilibrium positions were dynamically determined from the interaction between the fin and the vortical fluid environment. The equilibrium position depended on the initial longitudinal position and the phase of the fin heaving motion with respect to the phase of the vortex shedding. The power input required to drive the heaving motion was reduced during the slaloming behavior.
Observation of three-mode parametric instability in a micromechanical resonator
Authors: Ganesan Adarsh , Do Cuong , Seshia Ashwin
Published: November 2016

We present systematic experimental observations of three-mode auto-parametric instability in a micromechanical resonator analogous to previous experimental observations of this effect in optical parametric resonators. The three-mode instability is triggered when a driven mode at frequency ωd couples to two lower frequency modes (frequencies ω1 and ω2) such that ωd = ω1 + ω2. Similar to the 2 mode instability, the phenomenon is seen to be threshold dependent and sensitive to driving conditions and system parameters. In support of the experimental observations, a dynamical model has also been specified.
Observation of Mg-induced structural and electronic properties of graphene
Authors: Park Heemin , Singh Laishram Tomba , Lee Paengro , Kim Jingul , Ryu Mintae , Hwang Chan-Cuk , Kim Kwang S. , Chung Jinwook
Published: November 2016

We report the formation of superstructures induced by Mg adatoms on a single layer graphene (SLG) formed on Ni(111) substrate, where a strong metallic parabolic band is found near the Fermi level at the Γ-point of the Brillouin zone. Our valence band and core level data obtained by using synchrotron photons indicate that Mg adatoms intercalate initially to lift the SLG from the Ni substrate to produce a well-defined π-band of SLG, and then the parabolic band appears upon adding extra Mg atoms on the Mg-intercalated SLG. Our scanning tunneling microscopy images from these systems show the presence of superstructures, a 2√3 × 2√3 phase for the intercalated Mg layer below the SLG and then a √7 × √7 phase for the Mg overlayer formed on the Mg-intercalated SLG. We discuss the physical implications of these superstructures and the associated parabolic band in terms of a possible graphene-based two-dimensional superconductivity.
Color center fluorescence and spin manipulation in single crystal, pyramidal diamond tips
Authors: Nelz Richard , Fuchs Philipp , Opaluch Oliver , Sonusen Selda , Savenko Natalia , Podgursky Vitali , Neu Elke
Published: November 2016

We investigate bright fluorescence of nitrogen (NV)- and silicon-vacancy color centers in pyramidal, single crystal diamond tips, which are commercially available as atomic force microscope probes. We coherently manipulate NV electronic spin ensembles with T2 = 7.7(3) μs. Color center lifetimes in different tip heights indicate effective refractive index effects and quenching. Using numerical simulations, we verify enhanced photon rates from emitters close to the pyramid apex rendering them promising as scanning probe sensors.
Lower limits of line resistance in nanocrystalline back end of line Cu interconnects
Authors: Hegde Ganesh , Bowen R. Chris , Rodder Mark S.
Published: November 2016

The strong non-linear increase in the Cu interconnect line resistance with decreasing linewidth presents a significant obstacle to their continued downscaling. In this letter we use the first principles density functional theory based electronic structure of Cu interconnects to find the lower limits of their line resistance for metal linewidths corresponding to future technology nodes. We find that even in the absence of scattering due to grain boundaries, edge roughness or interfaces, quantum confinement causes a severe increase in the line resistance of Cu. We also find that when the simplest scattering mechanism in the grain boundary scattering dominated limit is added to otherwise coherent electronic transmission in monocrystalline nanowires, the lower limit of line resistance is significantly higher than projected roadmap requirements in the International Technology Roadmap for Semiconductors.
Laser fluence dependence on emission dynamics of ultrafast laser induced copper plasma
Authors: Anoop K. K. , Harilal S. S. , Philip Reji , Bruzzese R. , Amoruso S.
Published: November 2016

The characteristic emission features of a laser-produced plasma depend strongly on the laser fluence. We investigated the spatial and temporal dynamics of neutrals and ions in a femtosecond laser (800 nm, ∼40 fs, Ti:Sapphire) induced copper plasma in vacuum using both optical emission spectroscopy (OES) and spectrally resolved two-dimensional (2D) imaging over a wide fluence range of 0.5–77.5 J/cm2. 2D fast gated monochromatic images showed a distinct plume splitting between the neutrals and ions, especially at moderate to higher fluence. OES studies at low to moderate laser fluence confirm intense neutral line emission over ion emission, whereas this trend changes at higher laser fluence with dominance of the latter. This evidences a clear change in the physical processes involved in the femtosecond laser-matter interaction at high input laser intensity. The obtained ion dynamics resulting from OES and spectrally resolved 2D imaging are compared with charged particle measurement employing Faraday cup and Langmuir probe; results showed good correlation.
Ion-beam induced atomic mixing in isotopically controlled silicon multilayers
Authors: Radek M. , Bracht H. , Liedke B. , Böttger R. , Posselt M.
Published: November 2016

Implantation of germanium (Ge), gallium (Ga), and arsenic (As) into crystalline and preamorphized isotopically controlled silicon (Si) multilayer structures at temperatures between 153 K and 973 K was performed to study the mechanisms mediating ion-beam induced atomic mixing. Secondary-ion-mass-spectrometry was applied to determine concentration-depth profiles of the stable isotopes before and after ion implantation. The intermixing is analytically described by a depth-dependent displacement function. The maximum displacement is found to depend not only on temperature and microstructure but also on the doping type of the implanted ion. Molecular dynamics calculations evaluate the contribution of cascade mixing, i.e., thermal-spike mixing, to the overall observed atomic mixing. Calculated and experimental results on the temperature dependence of ion-beam mixing in the amorphous and crystalline structures provide strong evidence for ion-beam induced enhanced crystallization and enhanced self-diffusion, respectively. On the other hand, the former process is confirmed by channeling Rutherford backscattering analyses of the amorphous layer thickness remaining after implantation, the latter process is consistently attributed to the formation of highly mobile Si di-interstitials formed under irradiation and in the course of damage annealing. The observed ion-beam mixing in Si is compared to recent results on ion-beam mixing of Ge isotope multilayers that, in contrast to Si, are fully described by thermal-spike mixing only.
On the applicability of STDP-based learning mechanisms to spiking neuron network models
Authors: Sboev A. , Vlasov D. , Serenko A. , Rybka R. , Moloshnikov I.
Published: November 2016

The ways to creating practically effective method for spiking neuron networks learning, that would be appropriate for implementing in neuromorphic hardware and at the same time based on the biologically plausible plasticity rules, namely, on STDP, are discussed. The influence of the amount of correlation between input and output spike trains on the learnability by different STDP rules is evaluated. A usability of alternative combined learning schemes, involving artificial and spiking neuron models is demonstrated on the iris benchmark task and on the practical task of gender recognition.
Surface and bulk plasmons of electron-hole plasma in semiconductor nanowires
Authors: Moradi Afshin
Published: November 2016

We use a simple, two-fluid model for the collective electrostatic response of a semiconductor cylindrical nanowire, which treats the electron and hole components as a two-species plasma system. An analytical expression of the dispersion relation is obtained for both surface and bulk modes by solving Poisson and hydrodynamic equations with appropriate boundary conditions. It is found that the electrostatic interaction between the fluids gives rise to splitting of the two types of modes (i.e., surface and bulk modes) into two groups. The results may be useful for understanding the collective dynamics of the nano-device semiconductor plasma.
Communication: Dopant-induced solvation of alkalis in liquid helium nanodroplets
Authors: Renzler Michael , Daxner Matthias , Kranabetter Lorenz , Kaiser Alexander , Hauser Andreas W. , Ernst Wolfgang E. , Lindinger Albrecht , Zillich Robert , Scheier Paul , Ellis Andrew M.
Published: November 2016

Alkali metal atoms and small alkali clusters are classic heliophobes and when in contact with liquid helium they reside in a dimple on the surface. Here we show that alkalis can be induced to submerge into liquid helium when a highly polarizable co-solute, C60, is added to a helium nanodroplet. Evidence is presented that shows that all sodium clusters, and probably single Na atoms, enter the helium droplet in the presence of C60. Even clusters of cesium, an extreme heliophobe, dissolve in liquid helium when C60 is added. The sole exception is atomic Cs, which remains at the surface.