bluuebunny/crossref_metadata_2025 huggingface dataset:
Responsive polymers for biosensing and protein delivery
Authors: Islam Molla R. , Gao Yongfeng , Li Xue , Serpe Michael J.
Published: February 2014

Responsive polymers have found their way into numerous sensing and drug delivery platforms; some examples of biosensing and protein delivery are highlighted here.
Energetics of charges in organic semiconductors and at organic donor–acceptor interfaces
Authors: Gorczak Natalie , Swart Marcel , Grozema Ferdinand C.
Published: February 2014

We calculated the energy landscape of charged molecules that is determined by electrostatic and induction interaction using the fully polarizable force field DRF90 in the bulk and at interfaces of the electron accepting material C60, and two exemplary electron donating materials pentacene and phthalocyanine.
IR action spectroscopy shows competitive oxazolone and diketopiperazine formation in peptides depends on peptide length and identity of terminal residue in the departing fragment
Authors: Morrison L. J. , Chamot-Rooke J. , Wysocki V. H.
Published: February 2014

Diketopiperazine formation in gas-phase peptides depends on the side-chain of the third residue.
Interaction of organic compounds and boron clusters with new silica matrices containing the phosphatidylcholine headgroup
Authors: Fan Ping , Stolte Stefan , Gabel Detlef
Published: February 2014

New matrices were prepared in order to understand the interaction of dodecaborate clusters with liposome surfaces. Interaction is not only through ionic forces, although the clusters are anions.
Assembly of indenamine derivatives through in situ formed N-sulfonyliminium ion initiated cyclization
Authors: Fan Xiaohui , Lv Hao , Guan Yong-Hong , Zhu Hong-Bo , Cui Xiao-Meng , Guo Kun
Published: February 2014

A facile access to indene frameworks through condensation of substituted cinnamylaldehydes and sulfonylamines under the catalysis of FeCl3 is reported.
Activation of [99(m)TcO4]− by phosphonium cations
Authors: Braband Henrik , Benz Michael , Tooyama Yuji , Alberto Roger
Published: February 2014

The robust [99mTcO4]− anion can be activated in aqueous solution by in situ mixed anhydride formation in the presence of quaternary phosphonium cations.
Electron-donor function of methanofullerenes in donor–acceptor bulk heterojunction systems
Authors: Ie Yutaka , Karakawa Makoto , Jinnai Seihou , Yoshida Hiroyuki , Saeki Akinori , Seki Shu , Yamamoto Shunsuke , Ohkita Hideo , Aso Yoshio
Published: February 2014

Electron-donor function of methanofullerenes in bulk heterojunction systems is demonstrated for the first time.
Stereospecific conversion of alcohols into pinacol boronic esters using lithiation–borylation methodology with pinacolborane
Authors: Roesner Stefan , Brown Christopher A. , Mohiti Maziar , Pulis Alexander P. , Rasappan Ramesh , Blair Daniel J. , Essafi Stéphanie , Leonori Daniele , Aggarwal Varinder K.
Published: February 2014

The synthesis of primary and secondary pinacol boronic esters via lithiation–borylation of carbamates and benzoates with pinacolborane is described.
An amphiphilic, catalytically active, vitamin B12 derivative
Authors: Giedyk M. , Fedosov S. N. , Gryko D.
Published: February 2014

The reaction of vitamin B12 with DMF-DMA and MeOH as a nucleophile affords cobalester, the first amphiphilic cobalamin derivative which is able to catalyze C–C bond forming reactions.
A rational design for the selective detection of dopamine using conducting polymers
Authors: Fabregat Georgina , Casanovas Jordi , Redondo Edurne , Armelin Elaine , Alemán Carlos
Published: February 2014

A conducting polymer for the selective detection of dopamine has been designed by combining experimental measurements and theoretical calculations.
Influence of reduction temperature on composition, particle size, and magnetic properties of CoFe alloy nanomaterials derived from layered double hydroxide precursors
Authors: Yang Shuangxia , Wang Lianying , Yue Shuang , Lu Yanluo , He Jing , Zhao Dongye
Published: February 2014

CoFe alloy nanomaterials with high thermal stability and excellent magnetic properties were prepared through reduction of layered double hydroxides precursors at various temperatures.
Synthesis, structure and reactivity of [o-(2,6-diisopropylphenyliminomethinyl)phenyl]selenenyl selenocyanate (RSeSeCN) and related derivatives
Authors: Rakesh Prakul , Singh Harkesh B. , Jasinski Jerry P. , Golen James A.
Published: February 2014

The synthesis, structure and reactivity of stable selenenyl selenocyanates having a strong Se–Se bond are reported.
Cation-selective electropreconcentration
Authors: Shin Il Hyung , Kim Ki-jung , Kim Jiman , Kim Hee Chan , Chun Honggu
Published: February 2014

A cation-selective microfluidic sample preconcentration system is described using anion-permselective TMSVE- or polyE-323-coated nanochannels or a positively charged nanoporous polymer (PDADMAC) placed between positively-surface-coated microchannels.
Defined topologically-complex protein matrices to manipulate cell shapeviathree-dimensional fiber-like patterns
Authors: Moraes Christopher , Kim Byoung Choul , Zhu Xiaoyue , Mills Kristen L. , Dixon Angela R. , Thouless M. D. , Takayama Shuichi
Published: February 2014

We develop a technique to generate well-defined adhesive micropatterns on topologically complex substrates, enabling the culture of individual cells in precisely-controlled, three-dimensional adhesive microstructures.
Mechanically tough, elastic and stable rope-like double nanohelices
Authors: Dai L. , Huang X. J. , Dong L. X. , Zhang Q. , Zhang L.
Published: February 2014

Mechanically tough, elastic and stable rope-like double nanohelices are investigated by applying the Cosserat curve theory.
One-step formation of responsive “dumbbell” nanoparticle dimers via quasi-two-dimensional polymer single crystals
Authors: Zhou Tian , Dong Bin , Qi Hao , Lau Hang Kuen , Li Christopher Y.
Published: February 2014

One-step formation of responsive “dumbbell” nanoparticle dimersviaquasi-two-dimensional polymer single crystals.
Synthesis of α-tribromomethylamines via Mg-mediated addition of bromoform to imines
Authors: Gopi Elumalai , Namboothiri Irishi N. N.
Published: February 2014

N-Sulfonyl- and N-Boc-imines undergo facile addition of bromoform in the presence of Mg to afford α-tribromomethyl N-sulfonyl- and N-Boc-amines.
Characterization of interactions between organic molecules and Co-Al-LDH using photo-physical techniques
Authors: Li Lei , Zhao Kongchao , Liu Pengfei , Zhu Kai
Published: February 2014

The guest 2-NSA intercalated into Co-Al-LDH and enhanced the blue emission due to the host–guest coordination interactions.
Lanthanum(iii) triflate supported on nanomagnetic γ-Fe2O3: a new magnetically recyclable heterogeneous Lewis acid for the one-pot synthesis of β-phosphonomalonates
Authors: Sobhani Sara , Pakdin-Parizi Zahra
Published: February 2014

A new magnetically recyclable heterogeneous Lewis acid was synthesized and used for the one-pot synthesis of β-phosphonomalonates.
Catalysis by metal–organic frameworks: proline and gold functionalized MOFs for the aldol and three-component coupling reactions
Authors: Lili Liu , Xin Zhang , Shumin Rang , Ying Yang , Xiaoping Dai , Jinsen Gao , Chunming Xu , Jing He
Published: February 2014

Homochiral MOFs were engineered using postsynthetic modification and a one-pot synthetic strategy. l-Proline functionalized IRMOF-3 show high ee for aldol reaction. Gold functionalized CUP-1 catalysts are highly efficient for the A3 coupling reaction.
Spontaneous emulsification in ionic liquid/water systems and its use for templating of solids
Authors: Kowacz Magdalena , Esperança José M. S. S. , Rebelo Luís Paulo N.
Published: February 2014

Spontaneous emulsification in an ionic liquid/water system (IL/W) imprinted in porous film (P) at the liquid/liquid interface and in crystalline shells encapsulating IL droplets.
Beamforming with opportunistic relaying for wireless security
Authors: Sarkar Mohammad Zahurul Islam , Ratnarajah Tharmalingam , Ding Zhiguo
Published: February 2014

The authors present a beamforming scheme with opportunistic relaying (namely opportunistic beamforming) for wireless security under amplify‐and‐forward (AF) and decode‐and‐forward (DF) strategies. The relay selection is performed using the method of distributed timers, where all the relays use their timers to estimate own instantaneous channel gains and compete to access the wireless medium according to their own channel conditions. The performance of opportunistic beamforming scheme in terms of secure outage probability is analysed and the beamforming problem as a semidefinite programming problem with its optimisation framework is formulated. The results show that, in an opportunistic beamforming scheme, competition among cooperative relays offers diversity benefits in the direction of destination that enhances secrecy rate (i.e. minimises secure outage probability) and adhere to the ‘opportunistic’ cooperation rule giving priority to the ‘best’ available relay even when they are not chosen to transmit but rather chosen to cooperatively listen. Opportunistic beamforming scheme with DF strategy enhances secrecy rate than the beamforming with multiple DF relays while in the case of AF strategy, it provides significant improvement in the secrecy rate compared to the opportunistic relaying, the equal‐power multiple‐relay transmission and the single‐relay transmission schemes.
Development of a robust active infrared‐based eye tracker
Authors: Coetzer Reinier C. , Hancke Gerhard P.
Published: February 2014

Eye tracking has a number of useful applications ranging from monitoring a vehicle driver for possible signs of fatigue, providing an interface to enable severely disabled people to communicate with others, to a number of medical applications. Most eye tracking applications require a non‐intrusive way of tracking the eyes, making a camera‐based approach a natural choice. However, although significant progress has been made in recent years, modern eye tracking systems still have not overcome a number of challenges including eye occlusions, variable ambient lighting conditions and inter‐subject variability. This study describes the development of a robust real‐time camera‐based eye tracker, which is mainly suitable for indoor applications. The developed eye tracker relies on the so‐called bright/dark pupil effect for both the eye detection and eye tracking phases. Furthermore, this study also aims to determine how strong the bright/dark pupil effect is among people from an African ethnical background, a feature that is very relevant to a country such as South Africa.
Burden of Maxillofacial Trauma at Level 1 Trauma Center
Authors: Kaul Ruchi Pathak , Sagar Sushma , Singhal Maneesh , Kumar Abhishek , Jaipuria Jiten , Misra Mahesh
Published: February 2014

There is an upward trend in facial injuries following changes in population pattern, increasing industrialization and urbanization, hence maxillofacial trauma is becoming a burden and a leading medical problem in emergency rooms worldwide. This study was performed to evaluate the pattern of maxillofacial fractures, associated injuries, and treatment used at Jai Prakash Narayan Apex Trauma Center (JPNATC), All India Institute of Medical Sciences (AIIMS), New Delhi, India, between January 2007 and June 2010. The study provides basis for establishment of trauma as major etiology of maxillofacial injuries and planning for preventive strategies. A retrospective study of patients seen and treated at JPNATC, AIIMS, New Delhi, between January 2007 and June 2010 was performed. Data extracted from patient records included etiology, age, sex, types and sites of fractures, treatment modality, and concomitant injuries. There were 795 fractures of the maxillofacial skeleton and 86 concomitant injuries from 542 patients. Road traffic accident (RTA) (56.8%) was the most common etiologic factor, followed by falls (22.3%) and fights (18.5%). The age range was from 3 to 75 years (mean, 34.7 years) with a peak incidence in the third decade with a male-to-female ratio of 3.7:1. The most common location of maxillofacial fractures was the mandible 615 (77%) and middle third 180 (23%). With regard to mandibular fractures, the body (29.6%) was the most common site, followed by the angle (24.4%), ramus (19.5%), dentoalveolar (14.6%), symphysis (11.0%), condyle (0.8%) while in the middle third, the nasal bone (36.7%) was the most common, followed by zygomatic bone (27.8), Lefort II (14.4), Lefort I (7.8%), dentoalveolar (10.0%), and Lefort III (3.3%). Majority of the patients were treated by open reduction and internal fixation (70.6). Concomitant injuries were 84 (10.8%) with orthopedic injuries accounting for the majority (63.9%). Head injury was associated in 16.3% of cases. RTA was the major etiologic factor of maxillofacial injuries in our setting and the young adult males were the main victims. Henceforth, establishment of regionalized, efficient, and focused trauma centers in various parts of the country particularly for acute trauma should be emphasized. Also, the laws regarding the precautions such as seat belts, speed limits, and traffic rules must be observed strictly to reduce the incidence of RTA.
A molecular dynamics study of translation-rotation coupling in the NaCN plastic crystal
Authors: Chelli Riccardo , Cardini Gianni , Califano Salvatore
Published: February 2014

The plastic phase of crystalline NaCN has been studied by molecular dynamics simulation. A good agreement with available experimental data has been obtained. A detailed analysis of the translation-rotation coupling has been performed in terms of collective and single-particle motion. Using site symmetry coordinates of the anion and of the surrounding cation cage, we have obtained a picture of the rotational motion of the anions in terms of a cage-aided mechanism.
The physics and chemistry of the Schottky barrier height
Authors: Tung Raymond T.
Published: February 2014

The formation of the Schottky barrier height (SBH) is a complex problem because of the dependence of the SBH on the atomic structure of the metal-semiconductor (MS) interface. Existing models of the SBH are too simple to realistically treat the chemistry exhibited at MS interfaces. This article points out, through examination of available experimental and theoretical results, that a comprehensive, quantum-mechanics-based picture of SBH formation can already be constructed, although no simple equations can emerge, which are applicable for all MS interfaces. Important concepts and principles in physics and chemistry that govern the formation of the SBH are described in detail, from which the experimental and theoretical results for individual MS interfaces can be understood. Strategies used and results obtained from recent investigations to systematically modify the SBH are also examined from the perspective of the physical and chemical principles of the MS interface.
Progress in the development and understanding of advanced low k and ultralow k dielectrics for very large-scale integrated interconnects—State of the art
Authors: Grill Alfred , Gates Stephen M. , Ryan Todd E. , Nguyen Son V. , Priyadarshini Deepika
Published: February 2014

The improved performance of the semiconductor microprocessors was achieved for several decades by continuous scaling of the device dimensions while using the same materials for all device generations. At the 0.25 μm technology node, the interconnect of the integrated circuit (IC) became the bottleneck to the improvement of IC performance. One solution was introduction of new materials to reduce the interconnect resistance-capacitance. After the replacement of Al with Cu in 1997, the inter- and intralevel dielectric insulator of the interconnect (ILD), SiO2, was replaced about 7 years later with the low dielectric constant (low-k) SiCOH at the 90 nm node. The subsequent scaling of the devices required the development of ultralow-k porous pSiCOH to maintain the capacitance of the interconnect as low as possible. The composition and porosity of pSiCOH dielectrics affected, among others, the resistance of the dielectrics to damage during integration processing and reduced their mechanical strength, thereby affecting the reliability of the VLSI microprocessor. New ILDs had to be developed to overcome such problems and enable the fabrication of reliable high performance devices. The capacitance of the interconnect is also affected by the dielectric caps separating the Cu conductor from the ILD. This effect has increasing impact as interconnect dimensions shrink further with each technology node. New caps with lower k values and smaller thickness have been developed to reduce the impact of the caps to the capacitance of the interconnect and enable fabrication of devices of high reliability. This paper reviews the development of advanced ultralow-k (ULK) ILD dielectrics and caps with reduced capacitance contributions and presents the state of the art of these interconnect dielectrics.
TiO2@Silica nanoparticles in a random laser: Strong relationship of silica shell thickness on scattering medium properties and random laser performance
Authors: Jimenez-Villar Ernesto , Mestre Valdeci , de Oliveira Paulo C. , Faustino Wagner M. , Silva D. S. , de Sá Gilberto F.
Published: February 2014

A TiO2@Silica nanoparticle has been introduced in a random laser. TiO2 particles with an average diameter of 0.41 μm were coated with silica shells of different thicknesses. Strong dependency of silica shell thickness on the medium scattering strength was found. A mathematical relationship between the scattering mean free path, random laser threshold, and random laser efficiency was developed. Higher efficiency, lower laser threshold, narrower bandwidth, and longest photobleaching lifetime were obtained in the random laser that had increased silica shell thickness. Optical colloidal stability and light coupling enhancement with scattering particles, provided by silica shell, should lead to improved laser performance.
High-speed camera observation of solution plasma during nanoparticles formation
Authors: Saito Genki , Nakasugi Yuki , Akiyama Tomohiro
Published: February 2014

The direct-current discharge plasma during nanoparticles formation was observed using a high-speed camera. Metallic plates of Au, Ni, Ti, and Zn were used as a cathode, and a Pt wire was used as an anode. Both electrodes were immersed in a 0.1M NaOH solution. The solution plasma with light emission was generated via the vapor layer surrounding the cathode by applying 190 V. The current concentration occurred at a certain point of the electrode surface, in which the electrode surface was partially melted to produce nanoparticles. According to the high-speed observation, many light-emitting points appeared on the metallic plate and immediately disappeared when a certain point was strongly heated to produce nanoparticles. Additionally, light emission points moved in a chain reaction; after the first emission point was generated, the next emission point tended to be generated in the space surrounding the first emission point. During electrolysis, holes were generated on the cathode. The current concentration strongly heated certain spots on the electrode, and the electrode momentarily melted or vaporized, resulting in the formation of nanoparticles.
A collapse of the cross-spectral function in phase noise metrology
Authors: Nelson C. W. , Hati A. , Howe D. A.
Published: February 2014

Cross-spectral analysis is a mathematical tool for extracting the power spectral density of a correlated signal from two time series in the presence of uncorrelated interfering signals. We demonstrate and explain a set of amplitude and phase conditions where the detection of the desired signal using cross-spectral analysis fails partially or entirely in the presence of a second uncorrelated signal. Not understanding when and how this effect occurs can lead to dramatic under-reporting of the desired signal. Theoretical, simulated and experimental demonstrations of this effect as well as mitigating methods are presented.
Comparison of the interactions in the rare gas hydride and Group 2 metal hydride anions
Authors: Harris Joe P. , Manship Daniel R. , Breckenridge W. H. , Wright Timothy G.
Published: February 2014

We study both the rare gas hydride anions, RG–H− (RG = He–Rn) and Group 2 (Group IIa) metal hydride anions, MIIaH− (MIIa = Be–Ra), calculating potential energy curves at the CCSD(T) level with augmented quadruple and quintuple basis sets, and extrapolating the results to the basis set limit. We report spectroscopic parameters obtained from these curves; additionally, we study the Be–He complex. While the RG–H− and Be–He species are weakly bound, we show that, as with the previously studied BeH− and MgH− species, the other MIIaH− species are strongly bound, despite the interactions nominally also being between two closed shell species: M(ns2) and H−(1s2). We gain insight into the interactions using contour plots of the electron density changes and population analyses. For both series, the calculated dissociation energy is significantly less than the ion/induced-dipole attraction term, confirming that electron repulsion is important in these species; this effect is more dramatic for the MIIaH− species than for RG–H−. Our analyses lead us to conclude that the stronger interaction in the case of the MIIaH− species arises from sp and spd hybridization, which allows electron density on the MIIa atom to move away from the incoming H−.
Exploring size and state dynamics in CdSe quantum dots using two-dimensional electronic spectroscopy
Authors: Caram Justin R. , Zheng Haibin , Dahlberg Peter D. , Rolczynski Brian S. , Griffin Graham B. , Dolzhnikov Dmitriy S. , Talapin Dmitri V. , Engel Gregory S.
Published: February 2014

Development of optoelectronic technologies based on quantum dots depends on measuring, optimizing, and ultimately predicting charge carrier dynamics in the nanocrystal. In such systems, size inhomogeneity and the photoexcited population distribution among various excitonic states have distinct effects on electron and hole relaxation, which are difficult to distinguish spectroscopically. Two-dimensional electronic spectroscopy can help to untangle these effects by resolving excitation energy and subsequent nonlinear response in a single experiment. Using a filament-generated continuum as a pump and probe source, we collect two-dimensional spectra with sufficient spectral bandwidth to follow dynamics upon excitation of the lowest three optical transitions in a polydisperse ensemble of colloidal CdSe quantum dots. We first compare to prior transient absorption studies to confirm excitation-state-dependent dynamics such as increased surface-trapping upon excitation of hot electrons. Second, we demonstrate fast band-edge electron-hole pair solvation by ligand and phonon modes, as the ensemble relaxes to the photoluminescent state on a sub-picosecond time-scale. Third, we find that static disorder due to size polydispersity dominates the nonlinear response upon excitation into the hot electron manifold; this broadening mechanism stands in contrast to that of the band-edge exciton. Finally, we demonstrate excitation-energy dependent hot-carrier relaxation rates, and we describe how two-dimensional electronic spectroscopy can complement other transient nonlinear techniques.
Effect of quench rate on nanostructure and magnetic properties of PrCo5
Authors: Zhang W. Y. , Skomski R. , Li X. Z. , Valloppilly S. , Shield J. , Sellmyer David J.
Published: February 2014

The effect of quench rate on nanostructure and magnetic properties of PrCo5 alloy has been investigated. The increase of quench rate through wheel speed in melt spinning suppresses the formation of the secondary Pr2Co17 and Pr5Co19 phases with low magnetocrystalline anisotropy field and refines the nanostructure. This significantly improves the coercivity, remanence, and energy product. For example, increasing the wheel speed from 30 m/s to 70 m/s increases the coercivity and energy product from 3.2 kOe and 4.0 MGOe to 10.3 kOe and 13.7 MGOe, respectively. The magnetic hardening mechanism appears to be a mixture of reversed-domain-nucleation and domain-wall-pinning. The temperature coefficient of coercivity for the 70 m/s sample is −0.16%/K from 300 to 700 K, which is better than that of sintered SmCo5 magnets. Low temperature coefficients of coercivity and remanence indicate that rapidly quenched PrCo5 ribbons may be suitable for bonded magnets with high operation temperature.
High-frequency rotational losses in different soft magnetic composites
Authors: de la Barrière O. , Appino C. , Ragusa C. , Fiorillo F. , Mazaleyrat F. , LoBue M.
Published: February 2014

The isotropic properties of Soft Magnetic Composites (SMC) favor the design of new machine topologies and their granular structure can induce a potential decrease of the dynamic loss component. This paper is devoted to the characterization of the broadband magnetic losses of different SMC types under alternating and circular induction. The investigated materials differ by their grain size, heat treatment, compaction rate, and binder type. It is shown that, up to peak polarization Jp = 1.25 T, the ratios between the rotational and the alternating loss components (classical, hysteresis, and excess) are quite independent of the material structural details, quite analogous to the known behavior of nonoriented steel laminations. On the contrary, at higher inductions, it is observed that the Jp value at which the rotational hysteresis loss attains its maximum, related to the progressive disappearance of the domain walls under increasing rotational fields, decreases with the material susceptibility.
Magnetodielectric coupling in epitaxial Nd2CoMnO6 thin films with double perovskite structure
Authors: Anshul Avneesh , Kotnala R. K. , Aloysius R. P. , Gupta Anurag , Basheed G. A.
Published: February 2014

Double perovskite Nd2CoMnO6 thin films have been grown epitaxially on SrTiO3 substrates using pulsed laser deposition and their structural, magnetic, and dielectric properties were investigated. Temperature dependent dielectric (ε) constant is measured in the frequency range between 1 kHz and 1 MHz under applied magnetic fields up to 0.5 kOe. The dielectric constant exhibits an anomaly near to the Curie temperature which is independent of magnetic field and can be corroborated with a loop opening temperature in zero-field-cooled and field-cooled magnetization measurements. While, a linear relationship between magnetodielectric constant, δεMD, and M2(magnetization) in the paramagnetic to ferromagnetic regime proves magnetodielectric coupling between ferroelectric and ferromagnetic orders in this single-phase perovskite system.
Reducing disorder in graphene nanoribbons by chemical edge modification
Authors: Dauber J. , Terrés B. , Volk C. , Trellenkamp S. , Stampfer C.
Published: February 2014

We present electronic transport measurements on etched graphene nanoribbons on silicon dioxide before and after a short hydrofluoric acid (HF) treatment. We report on changes in the transport properties, in particular, in terms of a decreasing transport gap and a reduced doping level after HF dipping. Interestingly, the effective energy gap is nearly unaffected by the HF treatment. Additional measurements on a graphene nanoribbon with lateral graphene gates support strong indications that the HF significantly modifies the edges of the investigated nanoribbons leading to a significantly reduced disorder potential in these graphene nanostructures.
Broadband field rotator based on acoustic metamaterials
Authors: Jiang Xue , Liang Bin , Zou Xin-ye , Yin Lei-lei , Cheng Jian-chun
Published: February 2014

We have theoretically designed and experimentally realized a metamaterial-based acoustic field rotator that can be tailored to rotate the acoustic wavefront by a certain angle. For airborne sound, the designed field rotator simply comprises an array of identical plastic plates. The rotation effect and the broadband functionality of the resulting device have been demonstrated both numerically and experimentally. Excellent agreement is observed between the numerical simulation and experimental results. The realization of acoustic field rotator has offered possibility of acoustic manipulation and may have potential application in situations in need of special controls of acoustic wave.
Free vibrations of sensor diaphragm with residual stress coupled with liquids
Authors: Wu Huayong , Zhou Shenjie
Published: February 2014

The free vibrations of a micro-biochemical sensor diaphragm with residual stress in contact with a liquid are analyzed using the Rayleigh-Ritz method in the paper. A mechanics model based on a plate with residual stress is presented and analyzed when the plate vibrates in contact on one side with a liquid. The liquid is assumed to be incompressible and inviscid and the velocity potential is used to describe its irrotational motion. The Ritz solution is performed to find out the dependency of the natural frequency and the mode shape on the residual stress when the diaphragm vibrating in contact with a liquid. The results show that the residual stress significantly affects the natural frequency and the mode shape, and this is important to consider in the research and development of circular biochemical sensor diaphragms.
The flow rate sensitivity to voltage across four electrospray modes
Authors: Ryan C. N. , Smith K. L. , Stark J. P. W.
Published: February 2014

The influence of potential difference on the emitted flow rate across four modes of electrospray is described for an unrestricted electrospray system. The modes are those most commonly occurring; enhanced dripping, pulsation, cone-jet, and multi-jet. It is demonstrated that within three of these modes, the effect of voltage on flow rate is generally linear, with similar magnitude of gradient across all. The effect is demonstrated to be calculable across these three modes. This finding highlights that in the absence of any flow control mechanism, the influence of electrostatic pressure in driving the flow is the key process in voltage-driven electrospray.
Static magnetoelectric coupling of magnetoelectric laminated composites under combined temperature and stress loadings
Authors: Zhou Hao-Miao , Cui Xiao-Le
Published: February 2014

For the tri-layer symmetric magnetoelectric (ME) laminated composites made of giant magnetostrictive materials and piezoelectric materials, we chose the nonlinear magnetostrictive constitutive with variable coefficients and the linear piezoelectric constitutive to obtain the vibration equation for the laminated composites. The surface force and displacement speed were equivalent to the circuit voltage and current in the equivalent circuit for the laminated composites. According to the equivalent circuit, a model of the static magnetoelectric field coefficient for the strong nonlinear thermo-magneto-electro-mechanical coupling was obtained. Without considering the pre-stress, the comparisons of the static ME coefficient versus temperature curves for the experimental and theoretical results were in good agreement both qualitatively and quantitatively for low and moderate magnetic fields. The theoretical results were smaller than the experimental results under high magnetic fields. This model was adopted to predict variations in the ME coefficients in the laminated composites under different bias magnetic fields, temperatures, and stresses. This showed that the laminated composites had the strongest magnetoelectric effect at 0 °C; a large compressive stress effectively suppressed the magnetoelectric effect attenuation caused by high temperatures; an appropriate tensile stress improved the maximum magnetoelectric coefficient and lowered its bias magnetic field near room temperature. These results provide a theoretical basis for the design and application of high-performance and miniaturized magnetoelectric devices, operating under extreme temperature conditions.
Note: Development of ESS Bilbao's proton ion source: Ion Source Hydrogen Positive
Authors: Miracoli R. , Feuchtwanger J. , Arredondo I. , Belver D. , Gonzalez P. J. , Corres J. , Djekic S. , Echevarria P. , Eguiraun M. , Garmendia N. , Muguira L.
Published: February 2014

The Ion Source Hydrogen positive is a 2.7 GHz off-resonance microwave discharge ion source. It uses four coils to generate an axial magnetic field in the plasma chamber around 0.1 T that exceeds the ECR resonance field. A new magnetic system was designed as a combination of the four coils and soft iron in order to increase the reliability of the source. The description of the simulations of the magnetic field and the comparison with the magnetic measurements are presented. Moreover, results of the initial commissioning of the source for extraction voltage until 50 kV will be reported.
A site-selective antiferromagnetic ground state in layered pnictide-oxide BaTi2As2O
Authors: Yu Xiang-Long , Liu Da-Yong , Quan Ya-Min , Jia Ting , Lin Hai-Qing , Zou Liang-Jian
Published: February 2014

The electronic and magnetic properties of BaTi2As2O have been investigated using both the first-principles and analytical methods. The full-potential linearized augmented plane-wave calculations show that the most stable state is a site-selective antiferromagnetic (AFM) metal with a 2×1×1 magnetic unit cell containing two nonmagnetic Ti atoms and two other Ti atoms with antiparallel moments. Further analysis to Fermi surface and spin susceptibility shows that the site-selective AFM ground state is driven by the Fermi surface nesting and the Coulomb correlation. Meanwhile, the charge density distribution remains uniform, suggesting that the phase transition at 200 K in experiment is a spin-density-wave transition.
Anomalous Hall effect in Co/Ni multilayers with perpendicular magnetic anisotropy
Authors: Zhang Peng , Xie Kaixuan , Lin Weiwei , Wu Di , Sang Hai
Published: February 2014

Anomalous Hall effect is studied in Co/Ni multilayers with perpendicular magnetic anisotropy, which consists of ferromagnetic-ferromagnetic interfaces. The anomalous Hall coefficient of [Co/Ni]N multilayer increases with temperature. The anomalous Hall coefficient at the zero temperature limit is in the order of 0.01 μΩ cm/T and decreases with increasing the repetition N. It suggests that the Co-Ni interfacial contribution to anomalous Hall coefficient is of opposite sign to the bulk contribution. The anomalous Hall coefficient increases linearly with the resistivity of the Co/Ni multilayer, indicating the scattering may play a dominant role on the anomalous Hall effect.
Structural, electrical, and magnetic properties of SrRuO3 thin films
Authors: Kaur Pawanpreet , Sharma K. K. , Pandit Rabia , Choudhary R. J. , Kumar Ravi
Published: February 2014

Epitaxial thin films of SrRuO3 having thicknesses 100, 50, 25, and 12 nm have been grown on SrTiO3 (001) substrate by pulsed laser deposition technique. The thickness dependent resistivity analysis reveals the non-Fermi-liquid type behavior by obeying T1.5 temperature dependence below the transition temperature. Increase in disorder and correlation with decrease in the film thickness lead to the transition from metallic to insulating phase for 12 nm film. Magnetic studies suggest the destruction of ferromagnetism for this film. Magnetization obeys 3D mean field model for 100 nm film and 2D Ising model for 50 and 25 nm films.
Bias current dependence of the spin lifetime in insulating Al0.3Ga0.7As
Authors: Misuraca Jennifer , Kim Joon-Il , Lu Jun , Meng Kangkang , Chen Lin , Yu Xuezhe , Zhao Jianhua , Xiong Peng , von Molnár Stephan
Published: February 2014

The spin lifetime and Hanle signal amplitude dependence on bias current has been investigated in insulating Al0.3Ga0.7As:Si using a three-terminal Hanle effect geometry. The amplitudes of the Hanle signals are much larger for forward bias than for reverse bias, although the spin lifetimes found are statistically equivalent. The spin resistance-area product shows a strong increase with bias current for reverse bias and small forward bias until 150 μA, beyond which a weak dependence is observed. The spin lifetimes diminish substantially with increasing bias current. The dependence of the spin accumulation and lifetime diminish only moderately with temperature from 5 K to 30 K.
Low-loss waveguiding and detecting structure for surface plasmon polaritons
Authors: Fukuhara M. , Ota M. , Sakai H. , Aihara T. , Ishii Y. , Fukuda M.
Published: February 2014

A simple and low-loss metal/semiconductor surface plasmon polariton (SPP) device consisting of a SPP waveguide and a detector is studied theoretically and experimentally. We demonstrate a simple diffraction structure (a metal grating) where the SPP couples from the waveguide to the detector. The SPP can propagate without large losses at the air/Au interface, and this interface was used for SPP waveguiding. To convert the SPP into an electric signal using internal photoemission, the propagating SPP is coupled into the Au/Si interface by the diffraction structure. The propagation direction of the coupled SPP at the Au/Si interface depends on the slit pitch of the diffraction structure, and the direction can be controlled by adjusting the pitch. The slit pitch is also modeled using a diffraction grating equation, and the results show good agreement with those of simulations using the finite-difference time-domain method. When diffraction structures consisting of a multi-slit structure and a disk array are placed at the end of the waveguide, SPP coupling into the Au/Si interface is also observed. The photocurrents detected at the Au/Si interface are much larger when compared with that detected for the device without the diffraction structure (26 times for the multi-slit structure and 10 times for the disk array). From the polarization angle dependence of the detected photocurrent, we also confirmed that the photocurrent was caused by the SPP propagating at the air/Au interface.
Study on the wall ablation of heated compound-materials into discharge plasmas based on a modified model
Authors: Yang Lei , Liu Xiangyang , Wu Zhiwen , Wang Ningfei
Published: February 2014

Velocity of ablation vapor near the surface of heated compound-materials strongly affects the kinetic layer parameters modeled and manifested in the Knudsen layer. This paper discussed overlooked physics and clarified inaccuracies in the expression of velocity at the outer boundary of the kinetic layer induced by discharge plasma. The changes of average molecular mass coupling with discharge current on mass and momentum conservation equations in plasma layer were considered when modifying the expression of this boundary velocity. Our assessment of these effects indicated that velocity of ablation vapor showed a downtrend as the ratio of average molecular mass at inner and outer boundaries of plasma layer increased, which plays a decisive role in reducing the ablation rate. Compared with single species fluid model, the modified model that applies to the pyrolysis of heated compound-materials showed 56% drop in Teflon's ablation rate when plasmas were fully ionized.
Controllable generation of reactive oxygen species by femtosecond-laser irradiation
Authors: Yan Wei , He Hao , Wang Yintao , Wang Yisen , Hu Minglie , Wang Chingyue
Published: February 2014

Femtosecond lasers have been advancing Biophotonics research in the past two decades with multiphoton microscopy, microsurgery, and photodynamic therapy. Nevertheless, laser irradiation is identified to bring photodamage to cells via reactive oxygen species (ROS) generation with unclear mechanism. Meanwhile, currently in biological researches, there is no effective method to provide controllable ROS production precisely, which originally is leaked from mitochondria during respiration and plays a key role in a lot of important cellular processes and cellular signaling pathways. In this study, we show the process of how the tightly focused femtosecond-laser induces ROS generation solely in mitochondria at the very beginning and then release to cytosol if the stimulus is intense enough. At certain weak power levels, the laser pulses induce merely moderate Ca2+ release but this is necessary for the laser to generate ROS in mitochondria. Cellular original ROS are also involved with a small contribution. When the power is above a threshold, ROS are then released to cytosol, indicating photodamage overwhelming cellular repair ability. The mechanisms in those two cases are quite different. Those results clarify parts of the mechanism in laser-induced ROS generation. Hence, it is possible to further this optical scheme to provide controllable ROS generation for ROS-related biological researches including mitochondrial diseases and aging.
Electron density and temperature measurement by continuum radiation emitted from weakly ionized atmospheric pressure plasmas
Authors: Park Sanghoo , Choe Wonho , Youn Moon Se , Park Jaeyoung
Published: February 2014

The electron-atom neutral bremsstrahlung continuum radiation emitted from weakly ionized plasmas is investigated for electron density and temperature diagnostics. The continuum spectrum in 450–1000 nm emitted from the argon atmospheric pressure plasma is found to be in excellent agreement with the neutral bremsstrahlung formula with the electron-atom momentum transfer cross-section given by Popović. In 280–450 nm, however, a large discrepancy between the measured and the neutral bremsstrahlung emissivities is observed. We find that without accounting for the radiative H2 dissociation continuum, the temperature, and density measurements would be largely wrong, so that it should be taken into account for accurate measurement.
Optimization of oxidation processes to improve crystalline silicon solar cell emitters
Authors: Shen L. , Liang Z. C. , Liu C. F. , Long T. J. , Wang D. L.
Published: February 2014

Control of the oxidation process is one key issue in producing high-quality emitters for crystalline silicon solar cells. In this paper, the oxidation parameters of pre-oxidation time, oxygen concentration during pre-oxidation and pre-deposition and drive-in time were optimized by using orthogonal experiments. By analyzing experimental measurements of short-circuit current, open circuit voltage, series resistance and solar cell efficiency in solar cells with different sheet resistances which were produced by using different diffusion processes, we inferred that an emitter with a sheet resistance of approximately 70 Ω/□ performed best under the existing standard solar cell process. Further investigations were conducted on emitters with sheet resistances of approximately 70 Ω/□ that were obtained from different preparation processes. The results indicate that emitters with surface phosphorus concentrations between 4.96 × 1020 cm−3 and 7.78 × 1020 cm−3 and with junction depths between 0.46 μm and 0.55 μm possessed the best quality. With no extra processing, the final preparation of the crystalline silicon solar cell efficiency can reach 18.41%, which is an increase of 0.4%abs compared to conventional emitters with 50 Ω/□ sheet resistance.
Surface smoothing effect of an amorphous thin film deposited by atomic layer deposition on a surface with nano-sized roughness
Authors: Lau W. S. , Zhang J. , Wan X. , Luo J. K. , Xu Y. , Wong H.
Published: February 2014

Previously, Lau (one of the authors) pointed out that the deposition of an amorphous thin film by atomic layer deposition (ALD) on a substrate with nano-sized roughness probably has a surface smoothing effect. In this letter, polycrystalline zinc oxide deposited by ALD onto a smooth substrate was used as a substrate with nano-sized roughness. Atomic force microscopy (AFM) and cross-sectional transmission electron microscopy (XTEM) were used to demonstrate that an amorphous aluminum oxide thin film deposited by ALD can reduce the surface roughness of a polycrystalline zinc oxide coated substrate.
Temperature dependent dielectric function and the E critical points of hexagonal GaN from 30 to 690 K
Authors: Kim Tae Jung , Hwang Soon Yong , Byun Jun Seok , Barange Nilesh S. , Park Han Gyeol , Dong Kim Young
Published: February 2014

The complex dielectric function ɛ and the E0 excitonic and band-edge critical-point structures of hexagonal GaN are reported for temperatures from 30 to 690 K and energies from 0.74 to 6.42 eV, obtained by rotating-compensator spectroscopic ellipsometry on a 1.9 μm thick GaN film deposited on a c-plane (0001) sapphire substrate by molecular beam epitaxy. Direct inversion and B-splines in a multilayer-structure calculation were used to extract the optical properties of the film from the measured pseudodielectric function ⟨ɛ⟩. At low temperature sharp E0 excitonic and critical-point interband transitions are separately observed. Their temperature dependences were determined by fitting the data to the empirical Varshni relation and the phenomenological expression that contains the Bose-Einstein statistical factor.
In situ imaging of ultra-fast loss of nanostructure in nanoparticle aggregates
Authors: Egan Garth C. , Sullivan Kyle T. , LaGrange Thomas , Reed Bryan W. , Zachariah Michael R.
Published: February 2014

The word “nanoparticle” nominally elicits a vision of an isolated sphere; however, the vast bulk of nanoparticulate material exists in an aggregated state. This can have significant implications for applications such as combustion, catalysis, and optical excitation, where particles are exposed to high temperature and rapid heating conditions. In such environments, particles become susceptible to morphological changes which can reduce surface area, often to the detriment of functionality. Here, we report on thermally-induced coalescence which can occur in aluminum nanoparticle aggregates subjected to rapid heating (106–1011 K/s). Using dynamic transmission electron microscopy, we observed morphological changes in nanoparticle aggregates occurring in as little as a few nanoseconds after the onset of heating. The time-resolved probes reveal that the morphological changes initiate within 15 ns and are completed in less than 50 ns. The morphological changes were found to have a threshold temperature of about 1300 ± 50 K, as determined by millisecond-scale experiments with a calibrated heating stage. The temperature distribution of aggregates during laser heating was modeled with various simulation approaches. The results indicate that, under rapid heating conditions, coalescence occurs at an intermediate temperature between the melting points of aluminum and the aluminum oxide shell, and proceeds rapidly once this threshold temperature is reached.
Gold Catalysis: Biarylphosphine Ligands as Key for the Synthesis of Dihydroisocoumarins
Authors: Hashmi A. Stephen K. , Bechem Benjamin , Loos Annette , Hamzic Melissa , Rominger Frank , Rabaa Hassan
Published: February 2014

A gold-catalyzed phenol synthesis was successfully used in the synthesis of dihydroisocoumarins for the first time. A large number of gold(i) complexes were prepared and tested; only complexes based on the biarylphosphine motif were successful.
A functional typology of English when-clauses
Authors: Declerck Renaat
Published: February 2014

This paper offers a typology of English when-clauses (WCs) on the basis of their semantic, syntactic and functional characteristics. It distinguishes six major classes of dependent WCs: WCs used as indirect questions, relative clauses, free relative clauses in nominal function, adverbial WCs, narrative WCs and atemporal WCs. A further subciassification of these reveals many different categories and uses. All of these are illustrated lavishly, mostly with the help of attested examples. It is also shown that the various categories differ as regards the use of tense forms: some WCs can use the future tense auxiliary and/or combine with a head clause in the present tense or present perfect, whereas other WCs do not allow this.