bluuebunny/crossref_metadata_2025 huggingface dataset:
High-speed dual Langmuir probe
Authors: Lobbia Robert B. , Gallimore Alec D.
Published: July 2010

In an effort to temporally resolve the electron density, electron temperature, and plasma potential for turbulent plasma discharges, a unique high-speed dual Langmuir probe (HDLP) has been developed. A traditional single Langmuir probe of cylindrical geometry (exposed to the plasma) is swept simultaneously with a nearby capacitance and noise compensating null probe (fully insulated from the plasma) to enable bias sweep rates on a microsecond timescale. Traditional thin-sheath Langmuir probe theory is applied for interpretation of the collected probe data. Data at a sweep rate of 100 kHz are presented; however the developed system is capable of running at 1 MHz—near the upper limit of the applied electrostatic Langmuir probe theory for the investigated plasma conditions. Large sets (100 000 sweeps at each of 352 spatial locations) of contiguous turbulent plasma properties are collected using simple electronics for probe bias driving and current measurement attaining 80 dB signal-to-noise measurements with dc to 1 MHz bandwidth. Near- and far-field plume measurements with the HDLP system are performed downstream from a modern Hall effect thruster where the time-averaged plasma properties exhibit the approximate ranges: electron density ne from (1×1015)–(5×1016) m−3, electron temperature Te from 1 to 3.5 eV, and plasma potential Vp from 5 to 15 V. The thruster discharge of 200 V (constant anode potential) and 2 A (average discharge current) displays strong, 2.2 A peak-to-peak, current oscillations at 19 kHz, characteristic of the thruster “breathing mode” ionization instability. Large amplitude discharge current fluctuations are typical for most Hall thrusters, yet the HDLP system reveals the presence of the same 19 kHz fluctuations in ne(t), Te(t), and Vp(t) throughout the entire plume with peak-to-peak divided by mean plasma properties that average 94%. The propagation delays between the discharge current fluctuations and the corresponding plasma density fluctuations agree well with expected ion transit-times observed with distinct plasma waves traveling away from the thruster at velocities >10 km/s.
Intermolecular charge flux as the origin of infrared intensity enhancement upon halogen-bond formation of the peptide group
Authors: Torii Hajime
Published: July 2010

The changes in the vibrational properties of the peptide group upon formation of O⋯X and N⋯X halogen bonds are studied theoretically. Calculations are carried out for complexes of N-methylacetamide (NMA), a well known model molecule of the peptide group, with halogen-containing molecules. For comparison, calculations are also carried out for some NMA–water hydrogen-bonding complexes. It is shown that the infrared (IR) intensity of the amide I mode of the peptide group is enhanced significantly (up to about 520 km mol−1 or 2.6 times) upon CO⋯X halogen-bond formation, in spite of rather modest magnitudes of the intermolecular electric field and of the changes in the CO bond length and in the amide I vibrational frequency as compared with the cases of the CO⋯H(D) hydrogen bonding. From the analysis of the changes in the dipole derivative and in the electronic structure, it is shown that this IR intensity enhancement arises from the intermolecular charge flux. For the N⋯X halogen bonding complexes, some characteristic changes in the vibrational properties are seen, among which the IR intensity enhancement of the ND out-of-plane wagging mode is most notable. The reason why such large IR intensity enhancements are seen for these particular vibrational modes is examined.
Magnetic microstructures of neodymium in Nd2Fe14B permanent magnet by hard x-ray magnetic-circular dichroism using focused x-ray beam
Authors: Ueda Kazuhiro , Nambu Akira , Yoneyama Akio , Sugawara Akira , Heike Seiji , Hashizume Tomihiro , Suzuki Hiroyuki , Komuro Matahiro
Published: July 2010

Magnetic microstructures of neodymium (Nd) in a Nd–Fe–B magnet were investigated by the hard x-ray magnetic circular dichroism (HXMCD) with a focused synchrotron circular-polarized beam (<2 μm). Magnetic domain and Nd concentration were simultaneously acquired by measuring Nd HXMCD and Nd Lα intensity. The magnetic momentum of Nd was high for Nd2Fe14B microdomains but was nearly zero at Nd-rich precipitates. This clearly indicates the magnetic momentum distributions are well correlated with the local concentration of Nd. Our experiments demonstrate the feasibility of studying magnetic microstructures by HXMCD mapping, which thus enables a discussion of the bulk magnetic behavior of Nd–Fe–B magnets.
First passage time distribution in stochastic processes with moving and static absorbing boundaries with application to biological rupture experiments
Authors: Hu Zhonghan , Cheng Liwen , Berne B. J.
Published: July 2010

We develop and investigate an integral equation connecting the first passage time distribution of a stochastic process in the presence of an absorbing boundary condition and the corresponding Green’s function in the absence of the absorbing boundary. Analytical solutions to the integral equations are obtained for three diffusion processes in time-independent potentials which have been previously investigated by other methods. The integral equation provides an alternative way to analytically solve the three diffusion-controlled reactive processes. In order to help analyze biological rupture experiments, we further investigate the numerical solutions of the integral equation for a diffusion process in a time-dependent potential. Our numerical procedure, based on the exact integral equation, avoids the adiabatic approximation used in previous analytical theories and is useful for fitting the rupture force distribution data from single-molecule pulling experiments or molecular dynamics simulation data, especially at larger pulling speeds, larger cantilever spring constants, and smaller reaction rates. Stochastic simulation results confirm the validity of our numerical procedure. We suggest combining a previous analytical theory with our integral equation approach to analyze the kinetics of force induced rupture of biomacromolecules.
Multiple-scanning-probe tunneling microscope with nanoscale positional recognition function
Authors: Higuchi Seiji , Kuramochi Hiromi , Laurent Olivier , Komatsubara Takashi , Machida Shinichi , Aono Masakazu , Obori Kenichi , Nakayama Tomonobu
Published: July 2010

Over the past decade, multiple-scanning-probe microscope systems with independently controlled probes have been developed for nanoscale electrical measurements. We developed a quadruple-scanning-probe tunneling microscope (QSPTM) that can determine and control the probe position through scanning-probe imaging. The difficulty of operating multiple probes with submicrometer precision drastically increases with the number of probes. To solve problems such as determining the relative positions of the probes and avoiding of contact between the probes, we adopted sample-scanning methods to obtain four images simultaneously and developed an original control system for QSPTM operation with a function of automatic positional recognition. These improvements make the QSPTM a more practical and useful instrument since four images can now be reliably produced, and consequently the positioning of the four probes becomes easier owing to the reduced chance of accidental contact between the probes.
On the cluster composition of supercritical water combining molecular modeling and vibrational spectroscopic data
Authors: Tassaing T. , Garrain P. A. , Bégué D. , Baraille I.
Published: July 2010

The present study is aimed at a detailed analysis of supercritical water structure based on the combination of experimental vibrational spectra as well as molecular modeling calculations of isolated water clusters. We propose an equilibrium cluster composition model where supercritical water is considered as an ideal mixture of small water clusters (n=1–3) at the chemical equilibrium and the vibrational spectra are expected to result from the superposition of the spectra of the individual clusters, Thus, it was possible to extract from the decomposition of the midinfrared spectra the evolution of the partition of clusters in supercritical water as a function of density. The cluster composition predicted by this model was found to be quantitatively consistent with the near infrared and Raman spectra of supercritical water analyzed using the same procedure. We emphasize that such methodology could be applied to determine the portion of cluster in water in a wider thermodynamic range as well as in more complex aqueous supercritical solutions.
Experimental study of pancreaticojejunostomy completed using anastomotic chains
Authors: Pan Wei-Dong , Xu Rui-Yun , Li Nan , Fang He-Ping , Pan Cu-Zhi , Tang Zhao-Feng
Published: July 2010

The most difficult, time-consuming, and complication-prone step in pancreaticoduodenectomy is the pancreaticojejunostomy step. The largest disadvantage of this kind of anastomosis is the high incidence of postoperative anastomotic leakage. Once pancreatic leakage occurs, the patient death rate can be very high. The aim of this study was to design a pancreaticojejunostomy procedure using anastomotic chains, which results in the cut end of the jejunum being attached to the pancreatic stump without suturing, and to evaluate the safety and efficacy of this procedure in domestic pigs. The pancreaticojejunal anastomotic chains had the following structures: the chains consisted of two braceletlike chains made of titanium, named chain A and chain B. The function of chain A was to attach the free jejunal end onto the pancreatic stump, whereas the function of chain B was to tighten the contact between the jejunal wall and the surface of the pancreatic stump to eliminate gaps between the two structures and ensure tightness that is sufficient to guarantee that there is no leakage of jejunal fluid or pancreatic juice. The following procedure was used to assess the safety and efficacy of the procedure: pancreaticojejunostomies were performed on ten domestic pigs using anastomotic chains. The time required to complete the pancreaticojejunal anastomoses, the pressure tolerance of the pancreaticojejunal anastomoses, the pig death rate, and the histopathological examinations of the pancreaticojejunostomy tissues were recorded. The average time required to complete the pancreaticojejunal anastomosis procedure was 13±2 min. The observed tolerance pressure of the pancreaticojejunal anastomoses was more than 90 mm H2O. All ten domestic pigs that underwent operations were still alive four weeks after the operations. Pathological examinations showed that the anastomotic surfaces were completely healed, and the pancreatic cutting surfaces were primarily epithelialized. In conclusion, the use of anastomotic chains in pancreaticojejunostomy procedures results in a decrease in or elimination of pancreatic leakage. In addition, the procedure is simple to perform, is not time-intensive, and appears to be safe in a pig model.
Finite time Lagrangian analysis of an unsteady separation induced by a near wall wake
Authors: Ruiz T. , Borée J. , Tran T. T. , Sicot C. , Brizzi L. E.
Published: July 2010

Following the Lagrangian theory of unsteady flow separation on slip boundaries proposed by Lekien and Haller [“Unsteady flow separation on slip boundaries,” Phys. Fluids 20, 097101 (2008)], we use finite time Lagrangian analysis in order to educe large scale, unsteady flow separation downstream a near wall obstacle at a significant Reynolds number. By large scale flow separation, we mean here the ejection of fluid and vorticity outside a neighborhood of the wall at the scale of the obstacle. Indeed, while the separation point at the wall is not spatially resolved by the high speed particle image velocimetry measurements, free-slip boundary conditions are applied before educing unstable manifolds in the near wall region using finite time Lyapunov exponents. For this turbulent flow, conditional statistics are presented in order to discuss the relative contributions of the unsteady aerodynamics and of the turbulence in the separation region. The dynamics of the corresponding separation point has a very clear link with the fluctuating wall pressure induced by this unsteady turbulent flow.
Room temperature multiferroic Ba4Bi2Fe2Nb8O30: Structural, dielectric, and magnetic properties
Authors: Wu Y. J. , Hong Z. J. , Lin Y. Q. , Gu S. P. , Liu X. Q. , Chen X. M.
Published: July 2010

A room temperature multiferroic compound Ba4Bi2Fe2Nb8O30 was synthesized using a solid state reaction technique. Rietveld analysis of x-ray diffraction data shows that Ba4Bi2Fe2Nb8O30 has a tetragonal (space group P4bm) tungsten bronze structure. In this structure, the Fe3+ and Nb5+ statistically occupy the octahedral center while the Ba2+ ions and the Bi3+ ions occupy the pentagonal channels and the square channels, respectively. Diffuse dielectric peaks with strong frequency dispersion in the temperature range from 150 to 300 K can be attributed to the random distribution of Fe3+ and Nb5+ at B sites. Magnetic hysteresis loop at room temperature is also obtained, which suggests that Ba4Bi2Fe2Nb8O30 is a room temperature multiferroic compound. The coupling between the relaxor behavior and magnetic ordering is verified by observing an increase of magnetization near the maximum dielectric constant temperature.
Competing interparticle interactions and surface anisotropy in NiO nanoparticles
Authors: Meneses C. T. , Duque J. G. S. , de Biasi E. , Nunes W. C. , Sharma S. K. , Knobel M.
Published: July 2010

We report unconventional magnetic properties on NiO nanoparticles of an average diameter ∼5.8(7) nm obtained by coprecipitation method. To investigate the effect of the intra and interparticles interactions in the magnetic properties nanoparticles were dispersed in a polyvinyl-pyrrodone matrix at two different concentrations. X-ray, ac, and dc magnetization and ferromagnetic resonance experiments were carried out on powder and dispersed NiO systems. Our results show that dispersed and concentrated samples exhibit following two different magnetic behaviors: (i) a high temperature peak related to the blocking of the particle core and (ii) a low temperature maximum likely related to the freezing of the frustrated spins on surface particle. Besides, we have observed that the low temperature maximum is not field-dependent and depend strongly on the distance among particles. This result can be understood taking account the decreasing of the dipolar interaction to more dispersed samples.
Effects of average and local structure on the dielectric behavior of (1−x)BaTiO3–xLaYO3 (≤x≤0.40) ceramics
Authors: Feteira A. , Sinclair D. C. , Lanagan M. T.
Published: July 2010

The dielectric properties of dense ceramics of (1−x)BaTiO3–xLaYO3 (LBTY) (0≤x≤0.40) were characterized in the temperature range 10 to 450 K. The Curie temperature, Tc, of LBTY ceramics decreases at a rate of −23 K/at. % (La,Y) for x<0.10 but increases at +7 K/at. % (La,Y) for x≥0.20. The room temperature relative permittivity, εRT, decreases from ∼2000 for x=0.10 to ∼57 for x=0.40. This variation is accompanied by a substantial reduction in the temperature dependence of the relative permittivity, εr, and also by the emergence of relaxor ferroelectric-like behavior at x>0.05. The gradual transition from a classical ferroelectric to a relaxor-type response results from disruption of the long-range ferroelectric order, believed to be caused by a nanoclustering phenomenon. x=0.10 exhibits all the characteristic features of a relaxor-ferroelectric, i.e., εr decreases and tan δ increases with increasing frequency. For x>0.20 the relaxor behavior becomes progressively more subtle, suggesting a weaker coupling between the polar nanoregions. The poor microwave dielectric properties of LBTY ceramics, in particular for x=0.40, which exhibit εRT∼57 and a quality factor of ∼755 GHz are attributed to phase separation on the nanometer scale.
Energy level alignment and electrical properties of (Ba,Sr)TiO3/Al2O3 interfaces for tunable capacitors
Authors: Li Shunyi , Wachau André , Schafranek Robert , Klein Andreas , Zheng Yuliang , Jakoby Rolf
Published: July 2010

The interface formation between Ba0.6Sr0.4TiO3 and Al2O3 has been studied using photoelectron spectroscopy with in situ sample preparation. A negligible valence band discontinuity, corresponding to a ∼5.6 eV barrier for electron transport at the BST/Al2O3 interface is determined. Current-voltage measurements show that the leakage current can be significantly reduced by inserting the Al2O3 barrier layer between barium strontium titanate (BST) and Pt electrode. Different charge injection behavior depending on Al2O3 thickness is observed, which correspond well with the experimentally determined energy band diagrams. Direct tunneling from the metal electrode into the BST conduction band through the Al2O3 barrier layer is observed.
Crystallization of implanted amorphous silicon during millisecond annealing by infrared laser irradiation
Authors: Mannino Giovanni , Spinella Corrado , Ruggeri Rosa , La Magna Antonino , Fisicaro Giuseppe , Fazio Enza , Neri Fortunato , Privitera Vittorio
Published: July 2010

We investigated the homogenous nucleation of crystalline grains in amorphous Si during transient temperature pulse of few milliseconds IR laser irradiation. The crystallized volume fraction is ∼80%. Significant crystallization occurs in nonsteady regime because of the rapid temperature variation (106 °C/s). Our model combines the time evolution of the crystal grain population with the consumption of the amorphous volume due to the growth of grains. Thanks to the experimental approach based on a laser source to heat α-Si and the theoretical model we extended the description of the spontaneous crystallization up to 1323 K or 250 K above the temperature investigated by conventional annealing.
Temperature and electric field dependent mobility in poly(3-hexylthiophene) diodes
Authors: Giulianini Michele , Waclawik Eric R. , Bell John M. , Motta Nunzio
Published: July 2010

Current-voltage (I-V) curves of poly(3-hexylthiophene) (P3HT) diodes have been collected to investigate the polymer hole-dominated charge transport. At room temperature and at low electric fields the I-V characteristic is purely Ohmic whereas at medium-high electric fields, experimental data shows that the hole transport is trap dominated in the space charge limited current (SCLC) regime. In this regime, it is possible to extract the I-V characteristic of the P3HT/Al junction showing the ideal Schottky diode behavior over five orders of magnitude. At high-applied electric fields, holes’ transport is found to be in the trap free SCLC regime. We have measured and modeled in this regime the holes’ mobility to evaluate its dependence from the electric field applied and the temperature of the device.
Drop impact on microwetting patterned surfaces
Authors: Lee Minhee , Chang Young Soo , Kim Ho-Young
Published: July 2010

We investigate experimentally the dynamics of a liquid drop that impacts on a solid surface whose wettability is patterned at the microscopic scale. The target surface is patterned such that hydrophilic (hydrophobic) microscale spokes radiate from the center on a hydrophobic (hydrophilic) background. Following the initial spreading stages, the drop recoils on the hydrophobic region while being arrested on the hydrophilic area, thereby resulting in a micropatterned liquid footprint. We also find that the fingering instability of the drop edge is affected by the wettability patterns in the initial spreading stages. The number of fingers depends on a combination of the impact Weber number and the number of spokes. We suggest that the present scheme of patterning liquid deposits at microscales could be exploited in various microfluidic applications.
Physical limits of semiconductor laser operation: A time-resolved analysis of catastrophic optical damage
Authors: Ziegler Mathias , Hempel Martin , Larsen Henning E. , Tomm Jens W. , Andersen Peter E. , Clausen Sønnik , Elliott Stella N. , Elsaesser Thomas
Published: July 2010

The early stages of catastrophic optical damage (COD) in 808 nm emitting diode lasers are mapped by simultaneously monitoring the optical emission with a 1 ns time resolution and deriving the device temperature from thermal images. COD occurs in highly localized damage regions on a 30 to 400 ns time scale which is determined by the accumulation of excess energy absorbed from the optical output. We identify regimes in which COD is avoided by the proper choice of operation parameters.
Silicon oxide based n-doped layer for improved performance of thin film silicon solar cells
Authors: Delli Veneri Paola , Mercaldo Lucia V. , Usatii Iurie
Published: July 2010

We propose the use of n-doped silicon oxide as alternative n-layer in thin film Si p-i-n solar cells. By varying input gas ratios, films with a wide range of optical and electrical properties are obtained. Applying these layers in solar cells, good electrical and optical properties are demonstrated. A relative efficiency increase up to 13.6% has been observed on the cells adopting a simple Ag back contact. A similar spectral response as with the cell with standard n-layer plus ZnO/Ag back contact is obtained. The deposition of a buffer layer at the back contact can therefore be avoided.
Demonstration of edge roughness effect on the magnetization reversal of spin valve submicron wires
Authors: Chiang T. W. , Chang L. J. , Yu C. , Huang S. Y. , Chen D. C. , Yao Y. D. , Lee S. F.
Published: July 2010

We prepared submicron wide trilayer spin valve wires designed with periodic “spikes” as artificial roughness. The height and the pitch of the spikes were varied systematically. No obvious dependence was found between the roughness and the domain wall velocity when the spikes were smaller than a threshold of 30 nm for NiFe. The average velocity was slowed down when the height of the spikes were larger than the threshold. In-plane transverse magnetic fields help to reduce the critical current density for current induced domain-wall motion. Our results could be attributed to the space modulation of the local magnetization.
The aspect ratio effects on the performances of GaN-based light-emitting diodes with nanopatterned sapphire substrates
Authors: Kao Chien-Chih , Su Yan-Kuin , Lin Chuing-Liang , Chen Jian-Jhong
Published: July 2010

The nanopatterned sapphire substrates (NPSSs) with aspect ratio that varied from 2.00 to 2.50 were fabricated by nanoimprint lithography. We could improve the epitaxial film quality and enhance the light extraction efficiency by NPSS technique. In this work, the aspect ratio effects on the performances of GaN-based light-emitting diodes (LEDs) with NPSS were investigated. The light output enhancement of GaN-based LEDs with NPSS was increased from 11% to 27% as the aspect ratio of the NPSS increases from 2.00 to 2.50. Owing to the same improvement of crystalline quality by using various aspect ratios of NPSS, these results indicated that the aspect ratio of the NPSS is strongly related to the light extraction efficiency.
Enhancement of thermoelectric figure of merit in bismuth nanotubes
Authors: Zhou G. , Li L. , Li G. H.
Published: July 2010

Thermoelectric transport properties of bismuth nanotubes are theoretically predicted and mechanisms of the enhancement of the thermoelectric figure of merit (ZT) are discussed. A significant enhancement in ZT was found and is mainly attributed to the enhanced Seebeck coefficient resulting from the modified density of state and decreased phonon thermal conductivity induced by the boundary phonon scattering in nanotubes. The optimum power factor can be realized at the Fermi energy level locating near the subband edge, and the optimal ZT increases with decreasing the thickness and diameter of nanotubes.
Charge ordering of magnetic dipoles in artificial honeycomb patterns
Authors: Schumann A. , Sothmann B. , Szary P. , Zabel H.
Published: July 2010

Artificial spin ice offers the possibility to investigate a variety of dipolar orderings, spin frustrations and ground states. We have investigated magnetic dipoles arranged on a honeycomb lattice as a function of applied field, using magnetic force microscopy. The patterns were prepared by electron beam lithography where the basic units are polycrystalline Fe islands with dimensions length, width, and thickness of 3 μm, 0.3 μm, and 20 nm, respectively. These islands are in a single domain dipolar state at remanence. We have measured the magnetization reversal of the honeycomb patterns with different field directions. For the easy direction with the field parallel to one of the three dipole sublattices we observe at coercivity a maximum of magnetic charge order of alternating charges ±3, where the magnetic charge refers to the number and sign of magnetic poles pointing into any of the vertices.
Core-shell structure and unique faceting of Sn-catalyzed silicon nanowires
Authors: Yu Linwei , O’Donnell Benedict , Maurice Jean-Luc , Roca i Cabarrocas Pere
Published: July 2010

The potential of tin (Sn) as a catalyst for the vapor-liquid-solid (VLS) growth of silicon nanowires (SiNWs) has been relatively unexplored. Compared to the more commonly used catalysts (e.g., gold), Sn features a low eutectic point (at 235 °C) and a very low equilibrium Si solubility. These features make it possible to tune the supersaturation in the catalyst and the growth kinetics at the SiNW/catalyst interface. Here, we investigate the peculiarities of Sn-catalyzed VLS growth and show that the local growth kinetics, modified by the high supersaturation in the Sn catalyst, can lead to the formation of core-shell structures and sidewall faceting of the SiNWs. Challenges facing Sn-catalyzed growth of SiNWs in VLS mode are also discussed. We suggest that the unique features of Sn catalyst will help tailor SiNW structures to meet specific application needs.
Physicochemical Properties of New Dicationic Ether-Functionalized Low Melting Point Ammonium Salts
Authors: Kärnä Minna , Lahtinen Manu , Hakkarainen Pirkko-Leena , Valkonen Jussi
Published: July 2010

Eleven new and one previously known but insufficiently characterized dicationic quaternary ammonium (QA) salts were synthesized and characterized. They contain an ethoxy ethyl group either in a side chain and/or as spacer of the diammonium cation and have bromide, hexafluorophosphate (PF6–), bis(trifluoromethanesulfonyl)imide (TFSI), or trifluoromethanesulfonate (TFMS) as an anion. 1H and 13C techniques, mass spectrometry, and elemental analysis together with X-ray diffraction and thermoanalytical methods were used for their characterization both in the liquid and solid state. In addition, residual water content and viscosity measurements were made for the two room temperature ionic liquids (RTILs). Capillary electrophoresis was used to measure the conductivity of the RTILs. Crystal structures of four compounds were determined by X-ray single crystal diffraction, and powder diffraction was used to study the crystallinity of the solid salts and to compare the structural similarities between the single crystals and the microcrystalline bulk form. Two of the TFSI salts were liquids below room temperature, having liquid ranges of ~380 and 350°C, respectively, and seven out of 12 salts melted below 100°C. In addition, both the TFSI and PF6 salts exhibited high thermal stabilities decomposing at about, or above 300°C. Both RTILs presented moderate viscosities at elevated temperatures. The determined physicochemical properties of the reported ILs suggest their applicability for various applications such as heat transfer fluids, high temperature synthesis, and lubricants.
Benzdiynes and Related Dehydroaromatics
Authors: Sato Tadatake , Niino Hiroyuki
Published: July 2010

Benzdiynes, which are more unsaturated than benzyne, were proposed as reactive intermediates in the pyrolyses of aromatic dianhydrides in 1966. The generation and direct observation of these highly unsaturated species has been an experimental challenge. More than 30 years later, the first direct observation of a benzdiyne, 1,4-bis(trifluoromethyl)-2,3,5,6-tetradehydrobenzene, was reported. We outline the progress in the generation and observation of benzdiynes as well as theoretical studies on the background of benzyne chemistry. Spectroscopic observation of the benzdiynes, in particular detection of an IR band due to the asymmetric stretching of the two triple bonds, in conjunction with quantum chemical computations reveals their multireference character. In connection with the studies for generating benzdiynes, the studies for generating bisarynes with extended π-systems and the most highly unsaturated cyclic C6 are briefly reviewed.
Synthetic Methods for the Generation and Preparative Application of Benzyne
Authors: Kitamura Tsugio
Published: July 2010

Many methods have been developed for generating benzyne. Convenient and reliable precursors extensively studied so far involve benzenediazonium-2-carboxylate and o-dihalobenzenes such as 1,2-bromofluorobenzene and 1,2-dibromobenzene. Recently, in addition to the above precursors, o-(trimethylsilyl)phenyl triflate has been put into frequent use for benzyne reactions, in which benzyne is efficiently generated under mild conditions using fluoride ion. Furthermore, o-(trimethylsilyl)phenyliodonium triflate has been developed as a more efficient benzyne precursor. This mini-review focusses on recent progress in benzyne chemistry from the viewpoint of organic synthesis. The methods for generating benzynes are classified by the conditions into four categories: basic conditions using strong bases, mild conditions using fluoride ion, thermolysis, and oxidation.
Cubane: A New NMR Internal Standard
Authors: Chalmers Benjamin A. , Chen Annette P.-J. , Savage G. Paul , Williams Craig M.
Published: July 2010

Cubane can be considered the ideal internal standard for reactions observed by NMR, due to an almost complete benign reactivity and uniquely reliable 1H and 13C NMR resonances, in wide variety of deuterated solvents.
Structurally Perfect Ni3(µ1,3-N3)3 Triangles for a Magnetic Model
Authors: Liu Jun-Liang , Bao Xin , Herchel Radovan , Leng Ji-Dong , Lin Zhuo-Jia , Tong Ming-Liang
Published: July 2010

Two ideal triangular Ni3 compounds [Ni3(μ1,3-N3)3(2,2′-bpy)3]X3·3H2O (X = ClO4- (1) and BF4- (2); 2,2′-bpy = 2,2′-bipyridine) have, for the first time, been structurally and magnetically characterized, and represent a good model for us to understand the magnetic behaviours in extended azide-bridged nickel(II) complexes with trinuclear subunits.
Microwave Spectroscopy of Benzyne
Authors: Godfrey Peter D.
Published: July 2010

Although it had been proposed for several decades as the key transient intermediate in a well studied class of organic reaction, measurement and analysis of the gas-phase microwave absorption spectrum of the extremely reactive species o-benzyne represented a tremendous technical challenge. Initial success came after two decades of sustained technical development in the field of transient species microwave spectroscopy. Two decades later, comparably prodigious advances in microwave spectrometer instrumental sensitivity arising from Fourier transform microwave methods and in new chemical generation methods involving pulsed discharge nozzles have enabled a full isotopic substitution study leading to the determination of a precise molecular structure for gas-phase o-benzyne.
The Benzyne Story
Authors: Wentrup Curt
Published: July 2010

The history of o-benzyne from its early beginnings as an unobservable reactive intermediate until its present status as a very well characterized but still theoretically challenging molecule with important applications in synthesis is reviewed. The m- and p-benzynes, tridehydrobenzenes, and benzdiynes are also known, and p-benzyne is a key intermediate in the action of a potent class of ene-diyne anti-tumour compounds.
Remuneration differences in the emerging economies of China and India
Authors: Zhou Erhua (Iris) , Lu Zhao , Li Xiaoyan , Li Tian , Papola T. S. , Pais Jesim , Sahu Partha Pratim
Published: July 2010

Emerging economies by definition tend to be less dependent on expatriate skills and labour than lower‐income countries, yet remuneration (pay plus benefits) differences between expatriate and local workers persist in them to some degree. According to relative deprivation theory, economic development paradoxically elevates the salience of relatively small gaps in remuneration. We therefore expected workers to report injustice and demotivation regarding relative remuneration, despite the closing of remuneration gaps between expatriate and local workers due to the economic development of recent years. To explore that possibility, 482 skilled professionals from a variety of sectors and organizations in two emerging economies, India (n = 233, response rate = 54%) and China (n = 249, response rate = 58%), participated in the research. International salaries were greater than local salaries by a factor of 2.73:1 in India and 1.90:1 in China; these mean ratios bordered on intolerable in the India sample and were largely tolerable among the sample from China. In both countries, differently remunerated workers differed in their justice cognitions and their demotivation, with lowered motivation and fewer justice cognitions in the locally salaried, local workers. These differences were however more statistically significant between people working in India than in China. Insofar as the motivational and justice gaps persisted, the findings support relative deprivation theory. Insofar as the same gaps appear to be sharper in the country with the higher—not lower—mean remuneration differential, they do not. An in‐country workshop with local experts who interpreted the findings (in India), and content analysis of the participants’ recommendations (in China) jointly recommended linking remuneration to (i) workplace performance instead of (ii) economy‐of‐origin, to help promote (iii) fairness.
Responding to inequities: gorillas try to maintain their competitive advantage during play fights
Authors: Van Leeuwen Edwin J. C. , Zimmermann Elke , Ross Marina Davila
Published: July 2010

Humans respond to unfair situations in various ways. Experimental research has revealed that non-human species also respond to unequal situations in the form of inequity aversions when they have the disadvantage. The current study focused on play fights in gorillas to explore for the first time, to our knowledge, if/how non-human species respond to inequities in natural social settings. Hitting causes a naturally occurring inequity among individuals and here it was specifically assessed how the hitters and their partners engaged in play chases that followed the hitting. The results of this work showed that the hitters significantly more often moved first to run away immediately after the encounter than their partners. These findings provide evidence that non-human species respond to inequities by trying to maintain their competitive advantages. We conclude that non-human primates, like humans, may show different responses to inequities and that they may modify them depending on if they have the advantage or the disadvantage.
Multi-camera real-time three-dimensional tracking of multiple flying animals
Authors: Straw Andrew D. , Branson Kristin , Neumann Titus R. , Dickinson Michael H.
Published: July 2010

Automated tracking of animal movement allows analyses that would not otherwise be possible by providing great quantities of data. The additional capability of tracking in real time—with minimal latency—opens up the experimental possibility of manipulating sensory feedback, thus allowing detailed explorations of the neural basis for control of behaviour. Here, we describe a system capable of tracking the three-dimensional position and body orientation of animals such as flies and birds. The system operates with less than 40 ms latency and can track multiple animals simultaneously. To achieve these results, a multi-target tracking algorithm was developed based on the extended Kalman filter and the nearest neighbour standard filter data association algorithm. In one implementation, an 11-camera system is capable of tracking three flies simultaneously at 60 frames per second using a gigabit network of nine standard Intel Pentium 4 and Core 2 Duo computers. This manuscript presents the rationale and details of the algorithms employed and shows three implementations of the system. An experiment was performed using the tracking system to measure the effect of visual contrast on the flight speed ofDrosophila melanogaster. At low contrasts, speed is more variable and faster on average than at high contrasts. Thus, the system is already a useful tool to study the neurobiology and behaviour of freely flying animals. If combined with other techniques, such as ‘virtual reality’-type computer graphics or genetic manipulation, the tracking system would offer a powerful new way to investigate the biology of flying animals.
Molecular medicine; the road to the better integration of the medical sciences in the twenty-first century
Authors: Weatherall D. J.
Published: July 2010

The history of the evolution of medical research is characterized by a long period of division between the basic biological sciences and the health sciences, reflecting the seventeenth-century trends towards the experimental and the empirical. It was not until the middle of the twentieth century that, by their ability to straddle both worlds, the work of small groups of basic scientists in the USA and Europe led to closer integration between the medical sciences. This change in direction is well exemplified by the work of the Cambridge scientists Max Perutz, Vernon Ingram and Herman Lehmann, from 1950 onwards. Their research, and its later development by others, was to lay the basis for what became known as ‘molecular medicine’, and at the same time set the scene for a more integrated approach to medical research that continued into the new millennium.
A Royal Society for technology
Authors: Collins Peter
Published: July 2010

In the early 1960s the Royal Society came under increasing pressure to be seen to be fostering the applied sciences and technology. This was perceived to be a key element in improving Britain's industrial performance and international competitiveness. The Society was regarded as the body best able to raise the status of technology, just as it had raised the status of ‘pure’ science. The default position would be to create a separate, parallel body for technology, and a vigorous public debate from late 1963 raised this as a real possibility. This paper traces the Society's efforts through the rest of the decade to support technology with sufficient visibility and commitment to avert the creation of what might have been a rival academy. It succeeded—for a while.
Royal Society expeditions in the second half of the twentieth century
Authors: Hemmen George E.
Published: July 2010

During the second half of the twentieth century, the Royal Society mounted a number of scientific expeditions to different parts of the world. These expeditions varied considerably in their objectives, size, complexity and duration. Brief outlines of the main Royal Society expeditions of this period and their origins are given, together with mention of resulting Royal Society Discussion Meetings. Reference is also made to some long-term investigations involving the Society in collaboration with other countries' scientific institutions.
The Royal Society's formative role in UK space research
Authors: Pounds Ken
Published: July 2010

Before the formation of the Science Research Council (SRC) in 1965, the Royal Society played the key role, as both advocate and adviser to relevant government departments, in establishing the foundations of UK Space Research. The Society's Gassiot Committee was instrumental in the creation of a competitive university space research community, preparing the way for the active involvement of the UK in the NASA space science programme, and a leading role in Europe as founding members of the European Space Research Organisation, a forerunner of the European Space Agency. Although the Royal Society's formal responsibilities ended with the creation of the SRC, strong representation of Fellows within the early SRC structure helped ensure the continuity and growing international impact of UK space science. Although investment in space research in the UK subsequently fell well below that of other G7 nations (in GDP terms), the legacy of the efforts of the Royal Society can be found in the continuing high reputation of UK space science and in a strong UK space industry, which has a current annual turnover of £6 billion and a workforce of some 68 000.
Regional species pools control community saturation in lake phytoplankton
Authors: Ptacnik Robert , Andersen Tom , Brettum Pål , Lepistö Liisa , Willén Eva
Published: July 2010

Recent research has highlighted that positive biodiversity–ecosystem functioning relationships hold for all groups of organisms, including microbes. Yet, we still lack understanding regarding the drivers of microbial diversity, in particular, whether diversity of microbial communities is a matter of local factors, or whether metacommunities are of similar importance to what is known from higher organisms. Here, we explore the driving forces behind spatial variability in lake phytoplankton diversity in Fennoscandia. While phytoplankton biovolume is best predicted by local phosphorus concentrations, phytoplankton diversity (measured as genus richness,
G
) only showed weak correlations with local concentrations of total phosphorus. By estimating spatial averages of total phosphorus concentrations on various scales from an independent, spatially representative lake survey, we found that close to 70 per cent of the variability in local phytoplankton diversity can be explained by regionally averaged phosphorus concentrations on a scale between 100 and 400 km. Thus, the data strongly indicate the existence of metacommunities on this scale. Furthermore, we show a strong dependency between lake productivity and spatial community turnover. Thus, regional productivity affects beta-diversity by controlling spatial community turnover, resulting in scale-dependent productivity-diversity relationships. As an illustration of the interaction between local and regional processes in shaping microbial diversity, our results offer both empirical support and a plausible mechanism for the existence of common scaling rules in both the macrobial and the microbial worlds. We argue that awareness of regional species pools in phytoplankton and other unicellular organisms may critically improve our understanding of ecosystems and their susceptibility to anthropogenic stressors.
Dissecting the functional specificities of two Hox proteins
Authors: Joshi Rohit , Sun Liping , Mann Richard
Published: July 2010

Hox proteins frequently select and regulate their specific target genes with the help of cofactors like Extradenticle (Exd) and Homothorax (Hth). For the Drosophila Hox protein Sex combs reduced (Scr), Exd has been shown to position a normally unstructured portion of Scr so that two basic amino acid side chains can insert into the minor groove of an Scr-specific DNA-binding site. Here we provide evidence that another Drosophila Hox protein, Deformed (Dfd), uses a very similar mechanism to achieve specificity in vivo, thus generalizing this mechanism. Furthermore, we show that subtle differences in the way Dfd and Scr recognize their specific binding sites, in conjunction with non-DNA-binding domains, influence whether the target gene is transcriptionally activated or repressed. These results suggest that the interaction between these DNA-binding proteins and the DNA-binding site determines the architecture of the Hox–cofactor–DNA ternary complex, which in turn determines whether the complex recruits coactivators or corepressors.
Arabidopsis Plants Acclimate to Water Deficit at Low Cost through Changes of Carbon Usage: An Integrated Perspective Using Growth, Metabolite, Enzyme, and Gene Expression Analysis
Authors: Hummel Irène , Pantin Florent , Sulpice Ronan , Piques Maria , Rolland Gaëlle , Dauzat Myriam , Christophe Angélique , Pervent Marjorie , Bouteillé Marie , Stitt Mark , Gibon Yves , Muller Bertrand
Published: July 2010

Growth and carbon (C) fluxes are severely altered in plants exposed to soil water deficit. Correspondingly, it has been suggested that plants under water deficit suffer from C shortage. In this study, we test this hypothesis in Arabidopsis (Arabidopsis thaliana) by providing an overview of the responses of growth, C balance, metabolites, enzymes of the central metabolism, and a set of sugar-responsive genes to a sustained soil water deficit. The results show that under drought, rosette relative expansion rate is decreased more than photosynthesis, leading to a more positive C balance, while root growth is promoted. Several soluble metabolites accumulate in response to soil water deficit, with K+ and organic acids as the main contributors to osmotic adjustment. Osmotic adjustment costs only a small percentage of the daily photosynthetic C fixation. All C metabolites measured (not only starch and sugars but also organic acids and amino acids) show a diurnal turnover that often increased under water deficit, suggesting that these metabolites are readily available for being metabolized in situ or exported to roots. On the basis of 30 enzyme activities, no in-depth reprogramming of C metabolism was observed. Water deficit induces a shift of the expression level of a set of sugar-responsive genes that is indicative of increased, rather than decreased, C availability. These results converge to show that the differential impact of soil water deficit on photosynthesis and rosette expansion results in an increased availability of C for the roots, an increased turnover of C metabolites, and a low-cost C-based osmotic adjustment, and these responses are performed without major reformatting of the primary metabolism machinery.
An Atlas of Type I MADS Box Gene Expression during Female Gametophyte and Seed Development in Arabidopsis
Authors: Bemer Marian , Heijmans Klaas , Airoldi Chiara , Davies Brendan , Angenent Gerco C.
Published: July 2010

Members of the plant type I MADS domain subfamily have been reported to be involved in reproductive development in Arabidopsis (Arabidopsis thaliana). However, from the 61 type I genes in the Arabidopsis genome, only PHERES1, AGAMOUS-LIKE80 (AGL80), DIANA, AGL62, and AGL23 have been functionally characterized, which revealed important roles for these genes during female gametophyte and early seed development. The functions of the other genes are still unknown, despite the fact that the available single T-DNA insertion mutants have been largely investigated. The lack of mutant phenotypes is likely due to a considerable number of recent intrachromosomal duplications in the type I subfamily, resulting in nonfunctional genes in addition to a high level of redundancy. To enable a breakthrough in type I MADS box gene characterization, a framework needs to be established that allows the prediction of the functionality and redundancy of the type I genes. Here, we present a complete atlas of their expression patterns during female gametophyte and seed development in Arabidopsis, deduced from reporter lines containing translational fusions of the genes to green fluorescent protein and β-glucuronidase. All the expressed genes were revealed to be active in the female gametophyte or developing seed, indicating that the entire type I subfamily is involved in reproductive development in Arabidopsis. Interestingly, expression was predominantly observed in the central cell, antipodal cells, and chalazal endosperm. The combination of our expression results with phylogenetic and protein interaction data allows a better identification of putative redundantly acting genes and provides a useful tool for the functional characterization of the type I MADS box genes in Arabidopsis.