bluuebunny/crossref_metadata_2025 huggingface dataset:
Chiral imprinting in molten gallium
Authors: Kumar Vijay Bhooshan , Mastai Yitzhak , Porat Ze'ev , Gedanken Aharon
Published: January 2015

The question of the possibility of imprinting chirality in molten metals was addressed in the current paper. By optical rotation and CD measurements we have shown that chirality was indeed imprinted in molten Ga.
On the role of localized surface plasmon resonance in UV-Vis light irradiated Au/TiO2 photocatalysis systems: pros and cons
Authors: Lin Zhongjin , Wang Xiaohong , Liu Jun , Tian Zunyi , Dai Loucheng , He Beibei , Han Chao , Wu Yigui , Zeng Zhigang , Hu Zhiyu
Published: January 2015

The role of localized surface plasmon resonance (LSPR) in UV-Vis light irradiated Au/TiO2 photocatalysis systems has been investigated, and it is confirmed that both pros and cons of LSPR exist simultaneously.
Design and synthesis of a multivalent fluorescent folate–calix[4]arene conjugate: cancer cell penetration and intracellular localization
Authors: Consoli Grazia Maria Letizia , Granata Giuseppe , Fragassi Giorgia , Grossi Mauro , Sallese Michele , Geraci Corrada
Published: January 2015

Fluorescent multivalent folate–calix[4]arene–NBD selectively penetrates cancer cellsviafolate receptor-mediated endocytosis and localizes in endo-lysosomes.
BF3-Et2O mediated skeletal rearrangements of norbornyl appended cyclopentanediols
Authors: Nageswara Rao Chintada , Ahmed Khan Faiz
Published: January 2015

Synthetically useful norbornyl appended cyclopentenones and pinacolone products are reported during the BF3-Et2O mediated skeletal rearrangement of norbornyl appended cyclopentanediols.
Efficient phosphine ligands for the one-pot palladium-catalyzed borylation/Suzuki–Miyaura cross-coupling reaction
Authors: Chen You , Peng Hui , Pi Yun-Xiao , Meng Tong , Lian Ze-Yu , Yan Meng-Qi , Liu Yan , Liu Sheng-Hua , Yu Guang-Ao
Published: January 2015

An air-stable 2-(anthracen-9-yl)-1H-inden-3-yl dicyclohexylphosphine was used in palladium-catalyzed borylation/Suzuki–Miyaura cross-coupling reaction.
Physicochemical studies on the copper(ii) binding by glycated collagen telopeptides
Authors: Kamalov Meder , Harris Paul W. R. , Hartinger Christian G. , Miskelly Gordon M. , Cooper Garth J. S. , Brimble Margaret A.
Published: January 2015

The strong interaction between advanced glycation end-products and Cu(ii) ions has been revealed using site-specifically glycated collagenous peptides.
Synthesis of allylated quinolines/isoquinolines via palladium-catalyzed cyclization–allylation of azides and allyl methyl carbonate
Authors: Luo Jiang , Huo Zhibao , Fu Jun , Jin Fangming , Yamamoto Yoshinori
Published: January 2015

A novel and efficient strategy for one-step synthesis of allylated quinolines and isoquinolines via palladium-catalyzed cyclization–allylation of azides and allyl methyl carbonate is developed for the first time.
Chiral nanostructuring of multivalent macrocycles in solution and on surfaces
Authors: Caricato Marco , Delforge Arnaud , Bonifazi Davide , Dondi Daniele , Mazzanti Andrea , Pasini Dario
Published: January 2015

A chiral, multivalent macrocycle assembles upon metal–pyridine coordination into ordered nanostructures in solution and on surfaces.
Polymerization induced self-assembly: tuning of nano-object morphology by use of CO2
Authors: Dong Siming , Zhao Wei , Lucien Frank P. , Perrier Sébastien , Zetterlund Per B.
Published: January 2015

A novel method for synthesis of polymeric nano-objects via polymerization-induced self-assembly in a CO2-expanded medium has been developed.
Selective syntheses of leuconolam, leuconoxine, and mersicarpine alkaloids from a common intermediate through regiocontrolled cyclizations by Staudinger reactions
Authors: Li Zining , Geng Qian , Lv Zhe , Pritchett Beau P. , Baba Katsuaki , Numajiri Yoshitaka , Stoltz Brian M. , Liang Guangxin
Published: January 2015

Selective syntheses of alkaloids bearing distinct core structures were enabled by chemically programmed polycyclizations using water as a switch.
Controllable fabrication of nanostructured copper compound on a Cu substrate by a one-step route
Authors: Wang Yongqian , Jiang Tingting , Meng Dawei , Kong Junhan , Jia Hanxiang , Yu Meihua
Published: January 2015

Self-assembled nanostructured copper compound whose absorption edge covers the entire visible spectrum was explored amply and processes excellent photocatalytic activity.
A solution-processed high-efficiency p-NiO/n-ZnO heterojunction photodetector
Authors: Debnath Ratan , Xie Ting , Wen Baomei , Li Wei , Ha Jong Y. , Sullivan Nichole F. , Nguyen Nhan V. , Motayed Abhishek
Published: January 2015

Solution-processed high-efficiency p–n heterojunction photodetectors have been developed using transition metal oxides.
Porous hollow CuS nanospheres with prominent peroxidase-like activity prepared in large scale by a one-pot controllable hydrothermal step
Authors: Shu Qun Wei , Li Chun Mei , Gao Peng Fei , Gao Ming Xuan , Huang Cheng Zhi
Published: January 2015

Porous hollow CuS nanospheres with a variety of sizes were fabricated by an innovative one-pot method based on a facile template-assisted hydrothermal approach at low temperatures. The as-prepared CuS nanospheres exhibited a very prominent intrinsic peroxidase-like activity.
Retracted Article: Multiwalled carbon nanotube wrapped nanoflake graphene composites for sensitive biosensing of leviteracetum
Authors: Narang Jagriti , Malhotra Nitesh , Chauhan Nidhi , Pundir C. S.
Published: January 2015

Current research work presents the detection of leviteracetum by using nanoflakes of graphene (GNF) and multiwalled carbon nanotube (MWCNT) decorated on fluorine-doped tin oxide (FTO) glass as sensing platform.
Denticulatains A and B: unique stilbene–diterpene heterodimers from Macaranga denticulata
Authors: Yang Da-Song , Li Zi-Lei , Wang Xue , Yan Hui , Yang Yong-Ping , Luo Huai-Rong , Liu Ke-Chun , Xiao Wei-Lie , Li Xiao-Li
Published: January 2015

Two novel heterodimers were isolated from the fronds of Macaranga denticulata. They possess an unprecedented stilbene–diterpene-type skeleton, which represents a unique class of prenylated stilbene.
A potential pyrrhotite (Fe7S8) anode material for lithium storage
Authors: Zhang Kailong , Zhang Tingwei , Liang Jianwen , Zhu Yongchun , Lin Ning , Qian Yitai
Published: January 2015

A new kind of electrode material for lithium ion batteries was prepared by a one-step solid–solid reaction. The structure, morphology and electrochemical properties of the Fe7S8@C nanospheres were investigated.
Sulfur-doped porous carbon nanosheets as an advanced electrode material for supercapacitors
Authors: Deng Wenfang , Zhang Yijia , Yang Lu , Tan Yueming , Ma Ming , Xie Qingji
Published: January 2015

Sulfur-doped porous carbon nanosheets were synthesized and exhibited high capacitance performance when serving as an electrode material for supercapacitors.
Cerium functionalized PVA–chitosan composite nanofibers for effective remediation of ultra-low concentrations of Hg(ii) in water
Authors: Sharma Reena , Singh Nahar , Tiwari Sangeeta , Tiwari Sandeep K. , Dhakate Sanjay R.
Published: January 2015

Functionalized PVA–chitosan composites nanofibers effective for removal of very low concentration of mercury.
Hierarchical CdS nanostructure by Lawesson's reagent and its enhanced photocatalytic hydrogen production
Authors: Pandit Vikram U. , Arbuj Sudhir S. , Hawaldar Ranjit R. , Kshirsagar Pradnya V. , Deshmukh Amarsinh J. , Ambekar Jalindar D. , Mulik Uttam P. , Gosavi Suresh W. , Kale Bharat B.
Published: January 2015

Lawesson's reagent (LR) has been effectively exploited for the synthesis of hierarchical architectures of cadmium sulphide (CdS) nanostructures for the first time.
Revealing the properties of the cubic ZrO2 (111) surface by periodic DFT calculations: reducibility and stabilization through doping with aliovalent Y2O3
Authors: Ricca Chiara , Ringuedé Armelle , Cassir Michel , Adamo Carlo , Labat Frédéric
Published: January 2015

The reducibility of the clean cubic ZrO2 (111) surface, as well as its stabilization through doping, have been investigated by hybrid DFT calculations within a periodic approach and localized basis sets.
Foaming-assisted electrospinning of large-pore mesoporous ZnO nanofibers with tailored structures and enhanced photocatalytic activity
Authors: Ren Xiaolong , Ying Pengzhan , Yang Zuobao , Shang Minghui , Hou Huilin , Gao Fengmei
Published: January 2015

We have demonstrated the growth of large-pore mesoporous ZnO nanofibers with enhanced photocatalytic activity via an improved electrospinning strategy.
Interaction effect between Cr(OH)3passive layer formation and inhibitor adsorption on 3Cr steel surface
Authors: Zhu Jinyang , Xu Lining , Lu Minxu , Zhang Lei , Chang Wei
Published: January 2015

Interaction effect between Cr(OH)3passive layer formation and inhibitor adsorption was found on 3Cr steel surface.
Environmental application of an industrial waste as catalyst for the electro-Fenton-like treatment of organic pollutants
Authors: Alfaya Elena , Iglesias Olalla , Pazos Marta , Sanromán Maria Angeles
Published: January 2015

The application of acid mine drainage sludge (AMDS), an industrial waste with high metal content, as catalyst for the electro-Fenton-like technology on the treatment of organic polluted effluents has been investigated.
A density functional theory study on 3d metal/graphene for the removal of CO from H2feed gas in hydrogen fuel cells
Authors: Li Kai , Li Yang , Tang Hao , Jiao Menggai , Wang Ying , Wu Zhijian
Published: January 2015

In M/graphene (M = Sc–Cu) systems, Fe, Co and Ni show higher efficiency for the removal of CO from H2feed gas.
Theoretical studies of a 3D-to-planar structural transition in SinAl5−n+1,0,−1(n = 0–5) clusters
Authors: Zhu Jinzhen , Wang Beizhou , Liu Jianjun , Chen Huanwen , Zhang Wenqing
Published: January 2015

A novel ptC structure C2Al3−which is more stable in energy than the experimentally observed CAl42−.was firstly predicted The C2Al3−may become a building block to assembly some larger supermolecule containing multiple phC.
Chiral phosphine-phosphoramidite ligands for highly enantioselective hydrogenation of N-arylimines
Authors: Li Qing , Hou Chuan-Jin , Liu Xiao-Ning , Huang De-Zhi , Liu Yan-Jun , Yang Rui-Feng , Hu Xiang-Ping
Published: January 2015

The asymmetric hydrogenation ofN-arylimines with the chiral phosphine-phosphoramidite ligand, (Sc,Sa)-PEAPhos2b, has been developed, in which high turnover numbers and excellent enantioselectivity were achieved.
Raman-encoded microbeads for spectral multiplexing with SERS detection
Authors: Lai Yuming , Sun Shuqing , He Tao , Schlücker Sebastian , Wang Yuling
Published: January 2015

Spectral multiplexing on polystyrene beads by SERS was demonstrated by encoding the silica-encapsulated self-assembled monolayers of Raman reporter-coated gold nanoparticles.
A novel ratiometric pH probe for extreme acidity based on FRET and PET
Authors: Shen Shi-Li , Zhang Xiao-Fan , Bai Su-Yun , Miao Jun-Ying , Zhao Bao-Xiang
Published: January 2015

The ratiometric pH probe RC1 was constructed by coumarin–rhodamine dyad. RC1 with a pKa of 3.21 could be used for measuring pH in the range 2.20–4.20 with high selectivity and visualizing extremely acidic pH conditions in bacteria.
Sub-ppm electrical detection of hydrogen sulfide gas at room temperature based on printed copper acetate–gold nanoparticle composite films
Authors: Sarfraz J. , Määttänen A. , Törngren B. , Pesonen M. , Peltonen J. , Ihalainen P.
Published: January 2015

This paper presents the sub-ppm level electrical detection of H2S gas at room temperature using printed copper acetate–gold nanoparticle composite films either on (A) silver or (B) gold/AuNP electrodes.
Self-assembled nanoparticle micro-shells templated by liquid crystal sorting
Authors: Rodarte Andrea L. , Cao Blessing H. , Panesar Harmanpreet , Pandolfi Ronald J. , Quint Makiko , Edwards Lauren , Ghosh Sayantani , Hein Jason E. , Hirst Linda S.
Published: January 2015

A new process for the generation of micron-scale vesicle-like nanoparticle shells is reported. These constructs consist of a robust, thin spherical layer, composed of closely packed quantum dots (QDs) and are stabilized by ligand–ligand interactions. This process represents a versatile method for making non-planar 3D nano-assemblies.
High performance of polyimide/CaCu3Ti4O12@Ag hybrid films with enhanced dielectric permittivity and low dielectric loss
Authors: Yang Yang , Sun Haoliang , Yin Di , Lu Zhihong , Wei Jianhong , Xiong Rui , Shi Jing , Wang Ziyu , Liu Zhengyou , Lei Qingquan
Published: January 2015

This work reports the excellent dielectric properties of polyimide (PI) embedded with CaCu3Ti4O12(CCTO)/Ag nanoparticles (CCTO@Ag).
Uniform Pd–Pt alloy nanoparticles supported on graphite nanoplatelets with high electrocatalytic activity towards methanol oxidation
Authors: Zhang Genlei , Huang Chengde , Qin Ruijie , Shao Zechao , An De , Zhang Wen , Wang Yuxin
Published: January 2015

Uniformly dispersed Pd–Pt alloy catalysts with different Pt/Pd ratios on 1-pyrenecarboxylic acid (PCA) modified graphite nanoplatelets (GNPs) were obtained using a one-pot approach. The binary composition of these Pd–Pt/GNPs catalysts can be controlled by simply adjusting the molar ratio of the Pd and Pt precursors.
Fast and low temperature growth of electron transport layers for efficient perovskite solar cells
Authors: Zhang Jie , Juárez-Pérez Emilio José , Mora-Seró Iván , Viana Bruno , Pauporté Thierry
Published: January 2015

A fast, simple and low temperature growth technique is described for the preparation of high structural and optical quality ZnO layers. These layers are shown to act as efficient selective contacts in perovskite solar cells.
High performance graphene oxide/polyacrylonitrile composite pervaporation membranes for desalination applications
Authors: Liang Bin , Zhan Wu , Qi Genggeng. , Lin Sensen , Nan Qian , Liu Yuxuan , Cao Bing , Pan Kai
Published: January 2015

A GO/PAN pervaporation composite membrane was prepared and exhibited high desalination performance.
Uniform core–shell structured magnetic mesoporous TiO2 nanospheres as a highly efficient and stable sonocatalyst for the degradation of bisphenol-A
Authors: Qiu Pengpeng , Li Wei , Thokchom Binota , Park Beomguk , Cui Mingcan , Zhao Dongyuan , Khim Jeehyeong
Published: January 2015

Uniform core–shell structured magnetic mesoporous TiO2 as a highly efficient and stable sonocatalyst for the degradation of bisphenol-A.
A photonic crystal based sensing scheme for acetylcholine and acetylcholinesterase inhibitors
Authors: Fenzl Christoph , Genslein Christa , Zöpfl Alexander , Baeumner Antje J. , Hirsch Thomas
Published: January 2015

A 2-layer approach towards optical sensing of acetylcholine and detection of an acetylcholinesterase inhibitor using photonic crystal sensor technology.
Mixed interlayers at the interface between PEDOT:PSS and conjugated polymers provide charge transport control
Authors: Moulé Adam J. , Jung Min-Cherl , Rochester Chris W. , Tress Wolfgang , LaGrange Daniela , Jacobs Ian E. , Li Jun , Mauger Scott A. , Rail M. Diego , Lin Oliver , Bilsky David J. , Qi Yabing , Stroeve Pieter , Berben Louise A. , Riede Moritz
Published: January 2015

An insoluble polymer interlayer has a great effect on the charge injection from the PEDOT:PSS interface.
The nano-crystallization and fluorescence of terbium doped Na2O/K2O/CaO/CaF2/Al2O3/SiO2 glasses
Authors: Bocker Christian , Herrmann Andreas , Loch Peter , Rüssel Christian
Published: January 2015

Oxyfluoride glasses with the molar composition 59.3 SiO2·3.7 Al2O3·12.3 CaO·5.3 K2O·9.0 Na2O·10.4 CaF2 were doped with different Tb3+-concentrations (1 × 1019, 5 × 1019 and 1 × 1020 cm−3).
Large phenyl-substituted acenes by cycloaddition reactions of the 2,6-naphthodiyne synthon
Authors: Rodríguez-Lojo Diego , Pérez Dolores , Peña Diego , Guitián Enrique
Published: January 2015

Diverse large acenes with promising photoelectronic properties can be obtained simply by bisaryne cycloadditions.
Polymorphism of a polymer precursor: metastable glycolide polymorph recovered via large scale high-pressure experiments
Authors: Hutchison Ian B. , Delori Amit , Wang Xiao , Kamenev Konstantin V. , Urquhart Andrew J. , Oswald Iain D. H.
Published: January 2015

Using a large volume high-pressure press a new polymorph of an important precursor for biomedical polymers was isolated in gram quantities and used to seed crystallisation experiments at ambient pressure.
Introduction to papers published from the AIRMON symposium, Marseille, France, 15–19 June 2014
Authors: Görner Peter
Published: January 2015

Dr Peter Görner introduces papers published from the AIRMON symposium on Modern Principles of Air Monitoring and Biomonitoring.
A base-controlled chemoselective transfer hydrogenation of α,β-unsaturated ketones catalyzed by [IrCp*Cl2]2 with 2-propanol
Authors: Chen Shu-jie , Lu Guo-ping , Cai Chun
Published: January 2015

A simple homogeneous catalyst system based on commercially available [IrCp*Cl2]2 has been developed for the transfer hydrogenation of α,β-unsaturated ketones.
Diastereoselective synthesis of functionalised carbazoles via a sequential Diels–Alder/ene reaction strategy
Authors: Cowell Joseph , Abualnaja Matokah , Morton Stephanie , Linder Ruth , Buckingham Faye , Waddell Paul G. , Probert Michael R. , Hall Michael J.
Published: January 2015

A one-pot, three-component, synthesis of saturated carbazoles and related pyridazino[3,4-b]indoles is described, involving an intermolecular Diels–Alder/intermolecular ene reaction sequence with relative stereocontrol of up to four stereocentres.
A bulky and flexible electrocatalyst for efficient hydrogen evolution based on the growth of MoS2 nanoparticles on carbon nanofiber foam
Authors: Guo Xin , Cao Guo-lin , Ding Fei , Li Xinyuan , Zhen Shuyu , Xue Yi-fei , Yan Yi-ming , Liu Ting , Sun Ke-ning
Published: January 2015

A bulky and flexible MoS2/CNF foam was prepared and used as a high performance HER electrocatalyst.
Highly stretchable energy harvester using piezoelectric helical structure for wearable applications
Authors: Yun Daeyeon , Park Jungyong , Yun Kwang‐Seok
Published: January 2015

Proposed is a helical piezoelectric structure for a highly stretchable energy harvester to be applied on the human body. The proposed device consists of two counter‐wound helical structures around a zcore structure made of an elastic fabric string. The inner fabric helix is used to separate the outer piezoelectric helix from the core to obtain a highly stretchable device. When stretched by 60% of its initial length, the device generates a maximum output voltage and power of 140 Vp‐p and 0.6 mW, respectively, at an operation frequency of 4 Hz.
Study on slot irises for tunable filters using TE011 mode
Authors: Kwak Changsoo , Uhm Manseok , Yom In‐Bok
Published: January 2015

Tunable filters using the TE011 mode have slot irises for coupling between cavities. Unless the slot iris is appropriately designed, the coupling value of the iris varies as an operating frequency changes and the filter performance deteriorates as a result. In this reported work, it was found that the frequency‐dependent coupling characteristic of the slot iris can be minimised by locating the iris appropriately. Why the coupling of a slot iris changes when the operating frequency is tuned is explained and how to find the optimum location of the slot iris for minimum variation of the coupling value is presented. The proposed theory is verified by full‐wave EM simulations and experiments with a Ka‐band two‐pole filter.
Optimal SP training for spatially correlated MIMO channels under coloured noises
Authors: Tran N.N. , Nguyen H.X.
Published: January 2015

Based on convex programming for optimisation, the optimal superimposed (SP) training signal design is proposed for spatially correlated multiple‐input–multiple‐output (MIMO) channels in the presence of correlated symbols and coloured Gaussian noises. Simulation results show that the proposed training design can effectively estimate the channel and outperforms the existing designs.
Incremental scheduling scheme for indoor visible light communication
Authors: Huang Xin , Fu Xuequn , Xu Wei
Published: January 2015

Light‐emitting diode (LED) access point (AP) scheduling can provide both significant performance gains and flexible user access for visible light communications. However, the scheduling for multiple moving users, which requires adaptive LED AP scheduling for user movements and is practical in common scenarios, has so far rarely been studied. An incremental scheduling scheme is proposed to introduce a time division scheduling framework to solve the scheduling problem with multiple moving users. The proposed scheme consists of two phases: global scheduling and local scheduling. In the global scheduling phase, a scheduling scheme based on graph theory is proposed to assign users to different timeslots to eliminate inter‐user interference. In the local scheduling phase, the result of global scheduling is adjusted for user movements. Simulation results show that the proposed scheme improves system capacity with reduced complexity.
Sample selective filter in HEVC intra‐prediction for screen content video coding
Authors: Kang Je‐Won
Published: January 2015

An efficient screen content video coding method to adaptively turn on/off filters used for intra‐prediction is proposed. A block is classified into two categories based on a statistical property of a block and a transform coding mode in the compressed domain. Specifically, the Mahalanobis distance (MD) between the estimated probability density distribution and prediction samples in the left and top boundaries of the block to be coded and its transform coding mode is used. The set of the filters are disabled depending on the condition. Experimental results demonstrated that the proposed method outperforms the state‐of‐the‐art video coding standard, i.e. the high‐efficiency video coding/range extension (HEVC/RExt), in terms of rate‐distortion (R‐D) performance.
Method for the analysis of the preferences of network users
Authors: Shen Bo , Hu Bao‐Wen , Zhang Huan
Published: January 2015

At present, research on users’ preferences is becoming increasingly widespread. Traditional research used a simple cosine similarity algorithm to calculate the similarity between users and just focused on one factor. So, a more complete method is described for researching preferences by considering more factors of the network to analyse data. Two personalisation recommendation algorithms are given based on users’ preferences. These two algorithms mainly work on two aspects: one is the content‐based recommendation algorithm. It uses a cosine similarity algorithm to calculate the similarity between users, uses LDA to obtain improvement and uses screens according to a user impact factor. The other is a relation‐based recommendation algorithm. It uses the PersonalRank algorithm to calculate the similarity, and uses the weight of users’ communication behaviours to improve the algorithm. Finally, micro‐blog users’ data are analysed in detail, and the consequences of the two recommendation methods are fused based on the content of the results and recommendations. As a result, we obtained more accurate recommendation results and verified the feasibility of the algorithm by experimental analysis.
Experimental investigation into radar‐based central blood pressure estimation
Authors: Solberg Lars Erik , Aardal Øyvind , Berger Tor , Balasingham Ilangko , Fosse Erik , Hamran Svein‐Erik
Published: January 2015

To assess whether radar technology can be used for monitoring blood pressure via information from the aorta, two experiments were performed: (i) measurements on a phantom model and (ii) acquisitions on a human subject for in vivo experiments. A linear dependency of phase on radius in the radar echoes in the phantom model showed that the information regarding the radius of a circular, cylindrical object depended on the clutter environment: in a low‐clutter case two distinct reflections were identified, whereas in the high‐clutter case it was possible to extract a proxy. Radar echoes from antennas strapped to the back of a human subject showed a clear signature from a discernible, distinct reflector believed to be the aorta. However, as for the high‐clutter case, only a proxy for aortic radius is available as basis for estimation, which is most likely coupled with aortic displacements.
Low start‐up voltage dc–dc converter with negative voltage control for thermoelectric energy harvesting
Authors: Lei Pui‐Sun , Chang Robert Chen‐Hao , Chia Chu‐Hsiang , Lee Ming‐Shiun
Published: January 2015

This Letter presents a low start‐up voltage dc–dc converter for low‐power thermoelectric systems which uses a native n‐type MOS transistor as the start‐up switch. The start‐up voltage of the proposed converter is 300 mV and the converter does not need batteries to start up. The negative voltage control is proposed to reduce the leakage current caused by native n‐type transistor and increase the efficiency. The proposed converter was designed using standard 0.18 µm CMOS process with chip size of 0.388 mm2. The peak efficiency is 63% at load current of 1.5 mA. The proposed converter provides output voltage >1 V at maximum load current of 3.2 mA.
Adaptive hybrid simulations for multiscale stochastic reaction networks
Authors: Hepp Benjamin , Gupta Ankit , Khammash Mustafa
Published: January 2015

The probability distribution describing the state of a Stochastic Reaction Network (SRN) evolves according to the Chemical Master Equation (CME). It is common to estimate its solution using Monte Carlo methods such as the Stochastic Simulation Algorithm (SSA). In many cases, these simulations can take an impractical amount of computational time. Therefore, many methods have been developed that approximate sample paths of the underlying stochastic process and estimate the solution of the CME. A prominent class of these methods include hybrid methods that partition the set of species and the set of reactions into discrete and continuous subsets. Such a partition separates the dynamics into a discrete and a continuous part. Simulating such a stochastic process can be computationally much easier than simulating the exact discrete stochastic process with SSA. Moreover, the quasi-stationary assumption to approximate the dynamics of fast subnetworks can be applied for certain classes of networks. However, as the dynamics of a SRN evolves, these partitions may have to be adapted during the simulation. We develop a hybrid method that approximates the solution of a CME by automatically partitioning the reactions and species sets into discrete and continuous components and applying the quasi-stationary assumption on identifiable fast subnetworks. Our method does not require any user intervention and it adapts to exploit the changing timescale separation between reactions and/or changing magnitudes of copy-numbers of constituent species. We demonstrate the efficiency of the proposed method by considering examples from systems biology and showing that very good approximations to the exact probability distributions can be achieved in significantly less computational time. This is especially the case for systems with oscillatory dynamics, where the system dynamics change considerably throughout the time-period of interest.
Non-Markovian Quantum State Diffusion for temperature-dependent linear spectra of light harvesting aggregates
Authors: Ritschel Gerhard , Suess Daniel , Möbius Sebastian , Strunz Walter T. , Eisfeld Alexander
Published: January 2015

Non-Markovian Quantum State Diffusion (NMQSD) has turned out to be an efficient method to calculate excitonic properties of aggregates composed of organic chromophores, taking into account the coupling of electronic transitions to vibrational modes of the chromophores. NMQSD is an open quantum system approach that incorporates environmental degrees of freedom (the vibrations in our case) in a stochastic way. We show in this paper that for linear optical spectra (absorption, circular dichroism), no stochastics is needed, even for finite temperatures. Thus, the spectra can be obtained by propagating a single trajectory. To this end, we map a finite temperature environment to the zero temperature case using the so-called thermofield method. The resulting equations can then be solved efficiently by standard integrators.
Multifunctional surfaces produced by femtosecond laser pulses
Authors: Vorobyev A. Y. , Guo Chunlei
Published: January 2015

In this study, we create a multifunctional metal surface by producing a hierarchical nano/microstructure with femtosecond laser pulses. The multifunctional surface exhibits combined effects of dramatically enhanced broadband absorption, superhydrophobicity, and self-cleaning. The superhydrophobic effect is demonstrated by a falling water droplet repelled away from a structured surface with 30% of the droplet kinetic energy conserved, while the self-cleaning effect is shown by each water droplet taking away a significant amount of dust particles on the altered surface. The multifunctional surface is useful for light collection and water/dust repelling.
Negative polarity of phenyl-C61 butyric acid methyl ester adjacent to donor macromolecule domains
Authors: Alley Olivia J. , Wu Meng-Yin , Johns Gary L. , Dawidczyk Thomas J. , Hardigree Josué F. Martínez , Markovic Nina , Arnold Michael S. , Katz Howard E.
Published: January 2015

Interfacial fields within organic photovoltaics influence the movement of free charge carriers, including exciton dissociation and recombination. Open circuit voltage (Voc) can also be dependent on the interfacial fields, in the event that they modulate the energy gap between donor HOMO and acceptor LUMO. A rise in the vacuum level of the acceptor will increase the gap and the Voc, which can be beneficial for device efficiency. Here, we measure the interfacial potential differences at donor-acceptor junctions using Scanning Kelvin Probe Microscopy, and quantify how much of the potential difference originates from physical contact between the donor and acceptor. We see a statistically significant and pervasive negative polarity on the phenyl-C61 butyric acid methyl ester (PCBM) side of PCBM/donor junctions, which should also be present at the complex interfaces in bulk heterojunctions. This potential difference may originate from molecular dipoles, interfacial interactions with donor materials, and/or equilibrium charge transfer due to the higher work function and electron affinity of PCBM. We show that the contact between PCBM and poly(3-hexylthiophene) doubles the interfacial potential difference, a statistically significant difference. Control experiments determined that this potential difference was not due to charges trapped in the underlying substrate. The direction of the observed potential difference would lead to increased Voc, but would also pose a barrier to electrons being injected into the PCBM and make recombination more favorable. Our method may allow unique information to be obtained in new donor-acceptor junctions.
Two-dimensional, phase modulated lattice sums with application to the Helmholtz Green’s function
Authors: Linton C. M.
Published: January 2015

A class of two-dimensional phase modulated lattice sums in which the denominator is an indefinite quadratic polynomial Q is expressed in terms of a single, exponentially convergent series of elementary functions. This expression provides an extremely efficient method for the computation of the quasi-periodic Green’s function for the Helmholtz equation that arises in a number of physical contexts when studying wave propagation through a doubly periodic medium. For a class of sums in which Q is positive definite, our new result can be used to generate representations in terms of θ-functions which are significant generalisations of known results.
Two-component hybrid time-dependent density functional theory within the Tamm-Dancoff approximation
Authors: Kühn Michael , Weigend Florian
Published: January 2015

We report the implementation of a two-component variant of time-dependent density functional theory (TDDFT) for hybrid functionals that accounts for spin-orbit effects within the Tamm-Dancoff approximation (TDA) for closed-shell systems. The influence of the admixture of Hartree-Fock exchange on excitation energies is investigated for several atoms and diatomic molecules by comparison to numbers for pure density functionals obtained previously [M. Kühn and F. Weigend, J. Chem. Theory Comput. 9, 5341 (2013)]. It is further related to changes upon switching to the local density approximation or using the full TDDFT formalism instead of TDA. Efficiency is demonstrated for a comparably large system, Ir(ppy)3 (61 atoms, 1501 basis functions, lowest 10 excited states), which is a prototype molecule for organic light-emitting diodes, due to its “spin-forbidden” triplet-singlet transition.
Pressure-induced transformations of onion-like carbon nanospheres up to 48 GPa
Authors: Zhang Weiwei , Yao Mingguang , Fan Xianhong , Zhao Shijia , Chen Shuanglong , Gong Chen , Yuan Ye , Liu Ran , Liu Bingbing
Published: January 2015

Raman spectra of onion-like carbon nanospheres (OCNSs) have been studied under pressure up to 48 GPa. A transformation related to a change from sp2 to sp3 bonding of carbons in OCNSs was observed at pressures above 20 GPa. The Raman spectra exhibit some vibrational features similar to those of the theoretically proposed Z-carbon phase of cold-compressed graphite, while the transition pressure is obviously higher than that for graphite. In contrast to the transformations in compressed graphite, interlayer bonds are formed on the nanoscale between buckled layers in OCNSs under pressure due to the concentric configuration, and sp2-sp3 conversion is incomplete even up to 48 GPa. This is confirmed by TEM observations on the decompressed samples. Moreover, the onion-like carbon structure is extremely stable and can be recovered even after a compression cycle to 48 GPa. This high stability, beyond that of other sp2 carbon materials, is related to the unique onion-like configuration and to the interlayer bonding. The transformed material should have excellent mechanical properties so that it can sustain very high pressure.
Two-dimensional spatial manipulation of microparticles in continuous flows in acoustofluidic systems
Authors: Gao Lu , Wyatt Shields C. , Johnson Leah M. , Graves Steven W. , Yellen Benjamin B. , López Gabriel P.
Published: January 2015

We report a modeling and experimental study of techniques to acoustically focus particles flowing through a microfluidic channel. Our theoretical model differs from prior works in that we solve an approximate 2-D wave transmission model that accounts for wave propagation in both the solid and fluid phases. Our simulations indicate that particles can be effectively focused at driving frequencies as high as 10% off of the resonant condition. This conclusion is supported by experiments on the acoustic focusing of particles in nearly square microchannels, which are studied for different flow rates, driving frequencies and placements of the lead zirconate titanate transducer, either underneath the microchannel or underneath a parallel trough. The relative acoustic potential energy and the resultant velocity fields for particles with positive acoustic contrast coefficients are estimated in the 2-D limit. Confocal microscopy was used to observe the spatial distribution of the flowing microparticles in three dimensions. Through these studies, we show that a single driving frequency from a single piezoelectric actuator can induce the 2-D concentration of particles in a microchannel with a nearly square cross section, and we correlate these behaviors with theoretical predictions. We also show that it is possible to control the extent of focusing of the microparticles, and that it is possible to decouple the focusing of microparticles in the vertical direction from the lateral direction in rectangular channels with anisotropic cross sections. This study provides guidelines to design and operate microchip-based acoustofluidic devices for precise control over the spatial arrangement of microparticles for applications such as flow cytometry and cellular sorting.
Polymer based whispering gallery mode laser for biosensing applications
Authors: François Alexandre , Riesen Nicolas , Ji Hong , Afshar V. Shahraam , Monro Tanya M.
Published: January 2015

Whispering gallery mode lasers are of interest for a wide range of applications and especially biological sensing, exploiting the dependence of the resonance wavelengths on the surrounding refractive index. Upon lasing, the Q factors of the resonances are greatly improved, enabling measurements of wavelength shifts with increased accuracy. A way forward to improve the performance of the refractive index sensing mechanism is to reduce the size of the optical resonator, as the refractive index sensitivity is inversely proportional to the resonator dimensions. However, as the lasing threshold is believed to depend on the Q factor among other parameters, and the reduction of the microresonator size results in lower Q, this poses additional challenges for reaching the lasing threshold. In this letter, we demonstrate lasing in 10 μm diameter dye doped polystyrene microspheres in aqueous solution, the smallest polystyrene microsphere lasers ever reported in these conditions. We also investigate the dependence of the lasing threshold on the Q factor by changing the refractive index surrounding the sphere, highlighting a much stronger dependency than initially reported.
Theoretical study on the ground state of the polar alkali-metal-barium molecules: Potential energy curve and permanent dipole moment
Authors: Gou Dezhi , Kuang Xiaoyu , Gao Yufeng , Huo Dongming
Published: January 2015

In this paper, we systematically investigate the electronic structure for the 2Σ+ ground state of the polar alkali-metal-alkaline-earth-metal molecules BaAlk (Alk = Li, Na, K, Rb, and Cs). Potential energy curves and permanent dipole moments (PDMs) are determined using power quantum chemistry complete active space self-consistent field and multi-reference configuration interaction methods. Basic spectroscopic constants are derived from ro-vibrational bound state calculation. From the calculations, it is shown that BaK, BaRb, and BaCs molecules have moderate values of PDM at the equilibrium bond distance (BaK:1.62 D, BaRb:3.32 D, and BaCs:4.02 D). Besides, the equilibrium bond length (4.93 Å and 5.19 Å) and dissociation energy (0.1825 eV and 0.1817 eV) for the BaRb and BaCs are also obtained.
Beyond the random phase approximation: Stimulated Brillouin backscatter for finite laser coherence times
Authors: Korotkevich Alexander O. , Lushnikov Pavel M. , Rose Harvey A.
Published: January 2015

We developed a linear theory of backward stimulated Brillouin scatter (BSBS) of a spatially and temporally random laser beam relevant for laser fusion. Our analysis reveals a new collective regime of BSBS (CBSBS). Its intensity threshold is controlled by diffraction, once cTc exceeds a laser speckle length, with Tc the laser coherence time. The BSBS spatial gain rate is approximately the sum of that due to CBSBS, and a part which is independent of diffraction and varies linearly with Tc. The CBSBS spatial gain rate may be reduced significantly by the temporal bandwidth of KrF-based laser systems compared to the bandwidth currently available to temporally smoothed glass-based laser systems.
Ultrafast dynamics of type-II GaSb/GaAs quantum dots
Authors: Komolibus K. , Piwonski T. , Gradkowski K. , Reyner C. J. , Liang B. , Huyet G. , Huffaker D. L. , Houlihan J.
Published: January 2015

In this paper, room temperature two-colour pump-probe spectroscopy is employed to study ultrafast carrier dynamics in type-II GaSb/GaAs quantum dots. Our results demonstrate a strong dependency of carrier capture/escape processes on applied reverse bias voltage, probing wavelength and number of injected carriers. The extracted timescales as a function of both forward and reverse bias may provide important information for the design of efficient solar cells and quantum dot memories based on this material. The first few picoseconds of the dynamics reveal a complex behaviour with an interesting feature, which does not appear in devices based on type-I materials, and hence is linked to the unique carrier capture/escape processes possible in type-II structures.
On quantized Liénard oscillator and momentum dependent mass
Authors: Bagchi B. , Ghose Choudhury A. , Guha Partha
Published: January 2015

We examine the analytical structure of the nonlinear Liénard oscillator and show that it is a bi-Hamiltonian system depending upon the choice of the coupling parameters. While one has been recently studied in the context of a quantized momentum-dependent mass system, the other Hamiltonian also reflects a similar feature in the mass function and also depicts an isotonic character. We solve for such a Hamiltonian and give the complete solution in terms of a confluent hypergeometric function.
Observation of nonlinear bands in near-field scanning optical microscopy of a photonic-crystal waveguide
Authors: Singh A. , Ctistis G. , Huisman S. R. , Korterik J. P. , Mosk A. P. , Herek J. L. , Pinkse P. W. H.
Published: January 2015

We have measured the photonic bandstructure of GaAs photonic-crystal waveguides with high resolution in energy as well as in momentum using near-field scanning optical microscopy. Intriguingly, we observe additional bands that are not predicted by eigenmode solvers, as was recently demonstrated by Huisman et al. [Phys. Rev. B 86, 155154 (2012)]. We study the presence of these additional bands by performing measurements of these bands while varying the incident light power, revealing a non-linear power dependence. Here, we demonstrate experimentally and theoretically that the observed additional bands are caused by a waveguide-specific near-field tip effect not previously reported, which can significantly phase-modulate the detected field.
High critical currents in heavily doped (Gd,Y)Ba2Cu3Ox superconductor tapes
Authors: Selvamanickam V. , Gharahcheshmeh M. Heydari , Xu A. , Galstyan E. , Delgado L. , Cantoni C.
Published: January 2015

REBa2Cu3Ox ((REBCO), RE = rare earth) superconductor tapes with moderate levels of dopants have been optimized for high critical current density in low magnetic fields at 77 K, but they do not exhibit exemplary performance in conditions of interest for practical applications, i.e., temperatures less than 50 K and fields of 2–30 T. Heavy doping of REBCO tapes has been avoided by researchers thus far due to deterioration in properties. Here, we report achievement of critical current densities (Jc) above 20 MA/cm2 at 30 K, 3 T in heavily doped (25 mol. % Zr-added) (Gd,Y)Ba2Cu3Ox superconductor tapes, which is more than three times higher than the Jc typically obtained in moderately doped tapes. Pinning force levels above 1000 GN/m3 have also been attained at 20 K. A composition map of lift factor in Jc (ratio of Jc at 30 K, 3 T to the Jc at 77 K, 0 T) has been developed which reveals the optimum film composition to obtain lift factors above six, which is thrice the typical value. A highly c-axis aligned BaZrO3 (BZO) nanocolumn defect density of nearly 7 × 1011 cm−2 as well as 2–3 nm sized particles rich in Cu and Zr have been found in the high Jc films.
Current gain in sub-10 nm base GaN tunneling hot electron transistors with AlN emitter barrier
Authors: Yang Zhichao , Zhang Yuewei , Nath Digbijoy N. , Khurgin Jacob B. , Rajan Siddharth
Published: January 2015

We report on Gallium Nitride-based tunneling hot electron transistor amplifier with common-emitter current gain greater than 1. Small signal current gain up to 5 and dc current gain of 1.3 were attained in common-emitter configuration with collector current density in excess of 50 kA/cm2. The use of a combination of 1 nm GaN/3 nm AlN layers as an emitter tunneling barrier was found to improve the energy collimation of the injected electrons. These results represent demonstration of unipolar vertical transistors in the III-nitride system that can potentially lead to higher frequency and power microwave devices.
Quantum cascade laser based monitoring of CF2 radical concentration as a diagnostic tool of dielectric etching plasma processes
Authors: Hübner M. , Lang N. , Zimmermann S. , Schulz S. E. , Buchholtz W. , Röpcke J. , van Helden J. H.
Published: January 2015

Dielectric etching plasma processes for modern interlevel dielectrics become more and more complex by the introduction of new ultra low-k dielectrics. One challenge is the minimization of sidewall damage, while etching ultra low-k porous SiCOH by fluorocarbon plasmas. The optimization of this process requires a deeper understanding of the concentration of the CF2 radical, which acts as precursor in the polymerization of the etch sample surfaces. In an industrial dielectric etching plasma reactor, the CF2 radical was measured in situ using a continuous wave quantum cascade laser (cw-QCL) around 1106.2 cm−1. We measured Doppler-resolved ro-vibrational absorption lines and determined absolute densities using transitions in the ν3 fundamental band of CF2 with the aid of an improved simulation of the line strengths. We found that the CF2 radical concentration during the etching plasma process directly correlates to the layer structure of the etched wafer. Hence, this correlation can serve as a diagnostic tool of dielectric etching plasma processes. Applying QCL based absorption spectroscopy opens up the way for advanced process monitoring and etching controlling in semiconductor manufacturing.
Note: Position dependence of time signals picked off a microchannel plate detector
Authors: Ablikim U. , Zohrabi M. , Jochim Bethany , Berry B. , Severt T. , Carnes K. D. , Ben-Itzhak I.
Published: January 2015

Using an ultrafast laser and a precision mask, we demonstrate that time signals picked off directly from a microchannel plate detector depend on the position of the hit. This causes a time spread of about 280 ps, which can affect the quality of imaging measurements using large detectors.
Hybrid film of silver nanowires and carbon nanotubes as a transparent conductive layer in light-emitting diodes
Authors: Liu Bai , Li Chong , Liu Qiao-Li , Dong Jian , Guo Chun-Wei , Wu Hua , Zhou Hong-Yi , Fan Xiu-Jun , Guo Xia , Wang Cheng , Sun Xiao-Ming , Jin Yuan-Hao , Li Qun-Qing , Fan Shou-Shan
Published: January 2015

A hybrid film of carbon nanotubes (CNTs) and silver nanowires (AgNWs) that could be regarded as a parallel circuit of CNTs and AgNWs was developed, which exhibited a low sheet resistance of 23 Ω/sq and transmittance at 550 nm of 93%. The relatively high, intertube contact resistance of CNTs was reduced by the metallic AgNWs, which acted as bridges to aid carrier transport between CNTs. A hybrid film of CNTs and AgNWs was used as a transparent conductive layer in an AlGaInP light-emitting diode (LED). Including the hybrid film in the LED increased the optical output power by about 1.6 times and decreased the red shift of emission wavelength from 13.11 to 9.7.
An investigation of resonances in e+-H scattering embedded in Debye plasma
Authors: Ning Ye , Yan Zong-Chao , Ho Yew Kam
Published: January 2015

We carry out calculations for S-wave and P-wave resonances in e+-H scattering in weakly coupled Debye plasma in which the interaction between two charged particles is represented by a screened Coulomb potential. We employ the complex-scaling method with Hylleraas-type basis set to take correlation effects into account. In the complex-scaling treatment of the screened Coulomb potential, we first perform a Taylor series expansion for the exponential function that contains the distance r between two particles into a polynomial with various powers rn. We then make the complex scaling transformation of r→r eiθ in the expansion. The complex resonant eigenvalues are obtained by searching for stabilized points in the complex energy plane with respect to the changes of rotational angle θ and other parameters in the basis set.