bluuebunny/crossref_metadata_2025 huggingface dataset:
Aerosol complexity in megacities: From size‐resolved chemical composition to optical properties of the Beijing atmospheric particles
Authors: Roger Jean‐Claude , Guinot Benjamin , Cachier Hélène , Mallet Marc , Dubovik Oleg , Yu Tong
Published: September 2009

Megacities need adapted tools for the accurate modeling of aerosol impacts. For this purpose a new experimental data processing has been worked out for Beijing aerosols as case study. Size‐resolved aerosol particles were extensively sampled during winter and summer 2003 and subsequently fully chemically characterized. The product is an aerosol model presenting a new particle pattern (mode number, size and chemistry) without any prerequisite constrain either on the mode number or on each mode chemical composition. Six modes were found and five of them consistently appear as internally mixed particles organized around a black carbon or a dust core coated by organic and/or inorganic material. Data were checked by robust comparisons with other experimental data (particle number, sunphotometer‐derived derived data). We found the presence of two accumulation modes in different internal mixing and optical calculations show that the Beijing aerosol single scattering albedo (ωo # 0.90) is significantly higher than expected. Such an approach would allow realistic modeling of atmospheric particle impacts under complex situations.
Quantifying biological carbon export for the northwest North Atlantic continental shelves
Authors: Fennel Katja , Wilkin John
Published: September 2009

It has been suggested that continental shelf systems contribute disproportionately to the oceanic uptake of atmospheric CO2, but the magnitude of this flux and the relative contributions of different underlying mechanisms are poorly quantified. A biological continental shelf pump mechanism has been implied; however, the magnitude of this export depends on advective transport of carbon‐rich water off the shelf, a process that is difficult to observe directly. Here we use a physical‐biogeochemical model for the northeastern North American continental margin to estimate the uptake of atmospheric CO2, the fraction of this uptake that results from biological processes, and the transport of organic carbon off the shelf. Our results suggest that there is no systematic difference in the area‐normalized CO2 uptake between the shelf regions and the adjacent deep ocean. The advective transport of carbon‐rich water off the shelf is insufficient to drive a Continental Shelf Pump in this region.
Both solar wind‐magnetosphere coupling and ring current intensity control of the size of the auroral oval
Authors: Milan Stephen E.
Published: September 2009

Two years of observations of the Earth's aurorae by the Imager for Magnetopause‐to‐Aurora Global Exploration (IMAGE) spacecraft are investigated to determine the factors controlling the size of the ionospheric polar cap and hence the latitude of the auroral oval. Regression analysis of the size of the auroral oval with respect to solar wind‐magnetosphere coupling and the intensity of the Earth's ring current reveals that both play a role in determining the response of the aurora to geomagnetic storms. Specifically, we demonstrate that by considering the SW‐M coupling and ring current intensity together, the correlation with the radius of the auroral oval is significantly better than if the two factors are considered individually. The results are discussed in terms of the solar wind‐magnetosphere interaction and internal feedback of the ring current on circulation of plasma within the magnetosphere.
L shell distribution of energetic electrons at Saturn
Authors: Carbary J. F. , Mitchell D. G. , Krupp N. , Krimigis S. M.
Published: September 2009

Energetic electron fluxes (110–485 keV) observed by the MIMI/LEMMS instrument on the Cassini mission to Saturn were averaged into azimuthal bins and L shell bins for the period from day 150 2004 to day 366 2008. In local time, the electrons fluxes maximize on the night side between the Mimas and Rhea L shells and have a minimum near noon. This local time behavior may be a result of nightside injection combined with subcorotational drift in a nondipolar field. In SLS longitude, the electrons are smoothly distributed, showing no signs of spiral patterns on this multiyear timescale. The lower energy electrons (110–365 keV) form an inner belt near the Mimas L shell and an outer belt between the Dione and Rhea L shells.
Modeling atmospheric longwave radiation at the surface under cloudless skies
Authors: Viúdez‐Mora A. , Calbó J. , González J. A. , Jiménez M. A.
Published: September 2009

Downward atmospheric longwave radiation (DLR) is an important component of the terrestrial energy budget, strongly related with the greenhouse effect and therefore remarkably affecting the climate. In this study, DLR at the surface has been calculated using a one‐dimensional radiative transfer model, Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART). A sensitivity study has been performed in order to assess the influence of several variables on DLR levels for cloudless conditions. Among these variables, the atmospheric profiles of temperature and water content have been confirmed as the most important. Calculations have been compared with measurements made with pyrgeometers. The study has been applied to data from two European stations, Payerne (Switzerland) and Girona (Spain). For the Payerne case, for which radio soundings were available, calculations show differences with measurements in the range −2.7 ± 3.4 W m−2. For Girona, where no in situ radio soundings are available, soundings taken about 90 km away and atmospheric profiles from a gridded analysis (European Centre for Medium‐Range Weather Forecasts (ECMWF)) were used along with the meteorological information at screen level. In the latter case, differences between modeling and measurements were about 0.3 ± 9.4 W m−2. From our results, it is found that radiative transfer modeling of DLR can produce results that agree with measurements reasonably well even if no in situ radio soundings are available; the use of profiles from the ECMWF analyses does not greatly increase the bias, while the dispersion of differences is only slightly larger than the uncertainty of the measurements. It has also been confirmed that radiative transfer modeling produces better results than previously published simple parameterizations based only on surface measurements.
Methane emissions from newly created marshes in the drawdown area of the Three Gorges Reservoir
Authors: Chen Huai , Wu Yuyuan , Yuan Xingzhong , Gao Yongheng , Wu Ning , Zhu Dan
Published: September 2009

The study aimed to understand the methane (CH4) emission and its controlling factors in the Three Gorges Reservoir Region and to explore its implication for large dams. We measured CH4 emissions from four vegetation stands in newly created marshes in the drawdown area of the Three Gorges Reservoir, China, in the summer of 2008. The results showed highly spatial variations of methane emissions among the four stands, with the smallest emission (0.25 ± 0.65 mg CH4 m−2 h−1) in the Juncus amuricus stand, and the greatest (14.9 ± 10.9 mg CH4 m−2 h−1) in the Scirpus triqueter stand. We found that the spatial variations of CH4 emissions are caused by difference in standing water depth and dissolved organic carbon (DOC). Results also showed a special seasonal variation of CH4 emissions in this area, i.e., maximal emissions in early July followed by a low and steady value before the winter flooding. The seasonality of CH4 emissions was found closely related to temperature and standing water depth. Because of the large area of the drawdown zones for global dam reservoirs and a large CH4 emission rate, such newly created marshes should not be neglected when estimating CH4 emissions from reservoirs.
Inhibition of Complex Glycosylation Increases the Formation of PrPsc
Authors: Winklhofer Konstanze F. , Heller Ulrich , Reintjes Anja , Tatzelt Jörg
Published: September 2009

N‐linked glycans with complex structure have a major role in the biological activity of a wide variety of cell surface and secreted glycoproteins. Here, we show that geldanamycin, an inhibitor of Hsp90, interferes with the formation of complex glycosylated mammalian prion protein (PrPC). Similarly to inhibitors of α‐mannosidases, geldanamycin stabilized a high mannose PrPC glycoform and prevented the subsequent processing into complex structures. Moreover, a PrP/Grp94 complex could be isolated from geldanamycin‐treated cells, suggesting that Grp94 might play a role in the processing of PrPC in the endoplasmic reticulum. Inhibition of complex glycosylation did not interfere with the glycosylphosphatidylinositol (GPI) anchor attachment and cellular trafficking of high mannose PrPC to the outer leaflet of the plasma membrane. In scrapie‐infected neuroblastoma cells, however, high mannose PrPC glycoforms were preferred substrates for the formation of PrP‐scrapie (PrPSc). Our study reveals that complex glycosylation is dispensable for the cellular trafficking of PrPC, but modulates the formation of PrPSc.
Electrical mapping of microtubular structures by surface potential microscopy
Authors: Zhang Peng , Cantiello Horacio F.
Published: September 2009

Microtubules (MTs) are important cytoskeletal polymers that play an essential role in cell division and transport in all eukaryotes and information processing in neurons. MTs are highly charged polyelectrolytes, composed of hollow cylindrical arrangements of αβ-tubulin dimers. To date, there is little information about electrical properties of MTs. Here, we deposited and dried MTs onto a gold-plated surface to image their topology by atomic force microscopy (AFM), and determined their electrical mapping with surface potential microscopy (SPM). We found a strong linear correlation between the magnitude of relative surface potential and MT parameters, including diameter and height. AFM images confirmed the cylindrical topology of microtubular structures, and the presence of topological discontinuities along their surface, which may contribute to their unique electrical properties.
Surface polishing by electrochemical etching of p-type 4H SiC
Authors: Ke Y. , Yan F. , Devaty R. P. , Choyke W. J.
Published: September 2009

Electrochemical polishing of Si- and C-face p-type 4H SiC has been performed. Polishing the Si face leads to a smoother surface compared to the C face within the range of etching conditions studied. However, the results of additional experiments on C-face samples indicate that polishing a lower doped p-type material leads to improved surface quality for this face. Differences in polishing on the two faces are interpreted in terms of preferred electrochemical etching directions in SiC. Etching conditions such as HF concentration, doping, and etching current density were varied to obtain optimized values. Current-voltage plots (voltammograms) show a maximum electrochemical current density for the process. The polishing should be performed at a constant current density near this peak value to obtain both a smooth surface and a rapid rate of removal of material. In contrast to electrochemical polishing of silicon, we suggest that the applied current should match the rate at which the electrolyte can supply ions for reaction to obtain the smoothest surface required for microelectromechanical system device fabrication. Based on the experiments, we propose that, to obtain the smoothest SiC surface using electrochemical polishing, etching should be performed on Si-face p-type 4H SiC in dilute HF solution at the optimum current density determined by the current-voltage measurements.
Temperature-dependent luminescence of Ce3+ in gallium-substituted garnets
Authors: Hansel Rachael A. , Allison S. W. , Walker D. G.
Published: September 2009

The luminescent lifetime of cerium-doped yttrium aluminum garnet has been determined as a function of temperature and as a function of gallium content. We have shown that increasing gallium content decreases the decay lifetime and results in luminescence quenching at lower temperatures. The results are quantitatively explained using a configurational coordinate diagram.
Structural and magnetic phenomena in Ni53Mn25Al22 thin film prepared by rf magnetron sputtering
Authors: Srivastava Vijay Kumar , Srivastava Saurabh Kumar , Chatterjee Ratnamala , Gupta Govind , Shivprasad S. M. , Nigam A. K.
Published: September 2009

Magnetic and structural properties of Ni–Mn–Al thin films are investigated. It is demonstrated that the annealed film shows L21 phase at room temperature. Magnetometry measurements reveal that the annealed film is ferromagnetic and a first order transition in magnetization versus temperature measurement confirms that the martensite to austenite transition occurs around room temperature. Transmission electron microscopy measurements confirm that this structural change occurs just below room temperature. The splitting of Mn 2p3/2 level in x-ray photoelectron spectroscopy core level spectra of the annealed Ni–Mn–Al film, confirms that the origin of magnetism is definitely correlated with the local magnetic moment at the Mn atoms.
Self-assembled microarray of organic light-emitting diodes using a self-assembled monolayer by microcontact printing
Authors: Park Tae Hyun , Kim Young Min , Park Young Wook , Choi Jin Hwan , Jeong Jin-Wook , Choi Kyung Cheol , Ju Byeong-Kwon
Published: September 2009

A self-assembled microarray (SAMA) of organic light-emitting diodes (OLEDs) has been fabricated using self-assembled monolayers (SAMs) by microcontact printing (μCP). The hydrophobic methyl-terminated SAMs modify the surface properties of the substrates to become hydrophobic, i.e., with low surface energy. Thus, the hydrophobic SAMs pattern, by the μCP, can be applied to form SAMAs on the patterned SAMs since the difference of the local surface energy modifies the patterns on the substrates. In this study, octadecyltrichlorosilane based hydrophobic methyl-terminated SAMs have been used and the fabricated OLEDs, with the SAMAs show local light emissions on the micron scale with efficient performances.
Dissociation dynamics of C6H6 and C6H5F molecules following carbon 1s and fluorine 1s photoionization studied by three-dimensional momentum imaging method
Authors: Sugishima A. , Nagaya K. , Iwayama H. , Yao M. , Adachi J. , Kimura Y. , Yamazaki M. , Yagishita A.
Published: September 2009

Benzene and fluorobenzene molecules were multiply ionized through Auger decay following from the C 1s or the F 1s photoionization and their subsequent dissociations were studied utilizing position-sensitive time-of-flight measurements. The angular correlation between the momenta of (H+–H+) and (H+–F+) fragment ions derived from the multiply ionized benzene or fluorobenzene clearly reflects the hexagonal structure of the parent molecules, though the dissociations are not described by the simple Coulomb explosion model. Also, analysis on the planarity between the momentum of H+, C+, and F+ reveals that these three ions are emitted almost in a single plane.
Time-resolved luminescence studies of proton-implanted GaN
Authors: Pinos A. , Marcinkevičius S. , Usman M. , Hallén A.
Published: September 2009

Time-resolved photoluminescence measurements performed on proton implanted and annealed GaN layers have shown that carrier lifetime can be tuned over two orders of magnitude and, at implantation dose of 1×1015 cm−2, decreases down to a few picoseconds. With annealing at temperatures between 250 and 750 °C, carrier lifetime, contrary to electrical characteristics, is only slightly restored, indicating that electrical compensation and carrier dynamics are governed by different defects. Ga vacancies, free and bound at threading dislocations, are suggested as the most probable defects, responsible for electrical compensation and carrier lifetime quenching.
Tunable optofluidic switch via hydrodynamic control of laminar flow rate
Authors: Seow Y. C. , Lim S. P. , Lee H. P.
Published: September 2009

This letter reports a tunable planar optofluidic switch as illustrated by three laminar flow streams introduced into a focusing chamber. Different width of liquid core can be tuned via the imposed flow rate of these three laminar flow streams. The hydrodynamic tunability of the core-cladding interfaces is the key to realize microscale optical switching via total internal reflection. The optical switching capability is demonstrated having good agreement with optical simulations. The optofluidic optical switch can achieve a switching speed of 1.56 Hz and beyond with the potential for a seamless integration with other lab-on-a-chip devices for optical sensing applications.
Thermal nitridation passivation dependent band offset and electrical properties of AlOxNy/GaAs gate stacks
Authors: He G. , Zhang L. D. , Liu M.
Published: September 2009

Fermi level pinning attributed to oxides at the GaAs/high-k interface is a major obstacle to develop GaAs-based metal-oxide-semiconductor devices with high performance. In this letter, thermal nitridation treatment of GaAs surface prior to the high-k deposition is proposed to solve the issue of interface pinning. Results have confirmed that nitridation passivation effectively suppresses the oxides formation and leads to a shift in the Fermi level toward the conduction band minimum on the GaAs surface, which increases the conduction band offset at the GaAs/AlOxNy interface, followed by a saturated accumulation capacitance with reduced gate leakage current.
Configuration interaction calculations of potential curves and annihilation rates for positronic complexes of alkali monoxides
Authors: Buenker Robert J. , Liebermann Heinz-Peter
Published: September 2009

Ab initio multireference single- and double-excitation configuration interaction calculations have been carried out to compute the potential curves and annihilation rates (ARs) of positronic molecular complexes of a series of alkali monoxides. The dissociation limit for the lowest states of these systems consists of the positive alkali ion ground state (M+) and the OPs (e+O−) complex formed by attaching the positron to O−, even though the ground state of the corresponding neutral molecule always correlates with uncharged fragments (M+O). The positron affinity of the neutral oxide Π2 state is greater than that of Σ2+ in each case, so that the e+MO ground state always has Π3,1 symmetry, despite the fact that both KO and RbO have Σ2+ ground states. The bonding in the positronic systems is highly ionic at all internuclear distances and this causes their ARs to decrease gradually as the positive alkali ion approaches the OPs fragment.
Potentialphilicity and potentialphobicity: Reactivity indicators for external potential changes from density functional reactivity theory
Authors: Liu Shubin , Li Tonglei , Ayers Paul W.
Published: September 2009

In analogy to the electrophilicity, we define potentialphilicity indicators that represent energetically favorable ways to change the external potential of a molecule at fixed electron number. Similarly, we define a potentialphobicity to represent the least favorable way to change the external potential of a molecule. The resulting indicators should be useful for describing how molecular geometries change and predicting favorable and unfavorable ways for a reagent to approach a molecule. The linear response function enters plays a very important role in this approach, analogous to the role of the hardness for the electrophilicity or the hardness kernel for the Fukui function. The mathematical properties of the response function and its implications for these reactivity indicators are discussed in depth.
Field-modulated thermopower in SrTiO3-based field-effect transistors with amorphous 12CaO⋅7Al2O3 glass gate insulator
Authors: Ohta Hiromichi , Masuoka Yumi , Asahi Ryoji , Kato Takeharu , Ikuhara Yuichi , Nomura Kenji , Hosono Hideo
Published: September 2009

We report transistor characteristics and field-modulated thermopower (S) for single crystal SrTiO3-based field-effect transistors (FETs). We use 150-nm-thick amorphous 12CaO⋅7Al2O3 glass as the gate insulator of the SrTiO3-FET. The resulting SrTiO3-FET exhibits excellent transistor characteristics at room temperature: on-to-off current ratio greater than 106, threshold gate voltage of +1.1 V, subthreshold swing of approximately 0.3 V decade−1, and effective mobility of 2 cm2 V−1 s−1. The field-modulated S-value of the SrTiO3-FET varied from −900 to −580 μV K−1 with electric fields of up to 2 MV cm−1, demonstrating the effectiveness of the FET structure for the exploration of thermoelectric materials.
Excitation of microwaveguide modes by a stripe antenna
Authors: Demidov Vladislav E. , Kostylev Mikhail P. , Rott Karsten , Krzysteczko Patryk , Reiss Guenter , Demokritov Sergej O.
Published: September 2009

We have studied experimentally the excitation of propagating spin-wave modes of a microscopic Permalloy-film waveguide by a stripe antenna. We show that due to the strong quantization of the spin-wave spectrum, the excitation of particular modes has essentially different frequency dependencies leading to a nonmonotonous variation of the modulation depth of the resulting spin-wave beam as a function of the excitation frequency. In addition, we address the effect of nonreciprocity of spin-wave excitation and found that for the case of Permalloy microwaveguides this effect is much weaker pronounced than for waveguides made from dielectric magnetic films with low saturation magnetization.
Detection of defective DNA in carbon nanotubes by combined molecular dynamics/tight-binding technique
Authors: Xu Yang , Mi Xiaobing , Aluru N. R.
Published: September 2009

A tight-binding method combined with molecular dynamics (MD) is used to investigate the electrostatic signals generated by DNA segments inside short semiconducting single-wall carbon nanotubes (CNTs). The trajectories of DNA, ions, and waters, obtained from MD, are used in the tight-binding method to compute the electrostatic potential. The electrostatic signals indicate that when the DNA translocates through the CNT, it is possible to identify the total number of base pairs and the relative positions of the defective base pairs in DNA chains. Our calculations suggest that it is possible to differentiate Dickerson and hairpin DNA structures by comparing the signals.
Defect-free single-crystal Ge island arrays on insulator by rapid-melting-growth combined with seed-positioning technique
Authors: Toko Kaoru , Sakane Takashi , Tanaka Takanori , Sadoh Taizoh , Miyao Masanobu
Published: September 2009

Single-crystal Ge island arrays on SiO2/Si structures are desired to merge advanced Ge devices into Si large scale integrated circuit (LSI). We have developed the rapid-melting-growth process of amorphous Ge by using Ni-imprint-induced Si (111) fine crystals (∼1 μmϕ) as the growth seed. Arrays of (111) oriented single-crystal Ge islands with device size (∼10 μmϕ) are uniformly fabricated on SiO2/Si substrates. The cross-sectional transmission electron microscopy observation reveals that Ge islands include no dislocation or stacking fault. This method opens up a possibility to achieve hybrid SiGe-LSI with multifunctions.
Reduced contact resistances in organic transistors with secondary gates on source and drain electrodes
Authors: Nakayama K. , Uemura T. , Uno M. , Takeya J.
Published: September 2009

Secondary-gate electrodes under source and drain electrodes are introduced in organic thin-film transistors to reduce carrier-injection barriers into air-stable organic semiconductors. The additional gate electrodes buried in the gate insulators form “carrier-rich regions” in the vicinity of the source and drain electrodes with the application of sufficiently high local electric fields. Fabricating the structure with dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene, known for its excellent air stability, the contact resistance is drastically reduced especially at low gate voltages in the main channel. The result demonstrates carrier injection from the same material realizing a minimized potential barrier in the absence of interfacial trap levels for metal-to-semiconductor junctions.
Self-organized vertically aligned single-crystal silicon nanostructures with controlled shape and aspect ratio by reactive plasma etching
Authors: Xu S. , Levchenko I. , Huang S. Y. , Ostrikov K.
Published: September 2009

The formation of vertically aligned single-crystalline silicon nanostructures via “self-organized” maskless etching in Ar+H2 plasmas is studied. The shape and aspect ratio can be effectively controlled by the reactive plasma composition. In the optimum parameter space, single-crystalline pyramid-like nanostructures are produced; otherwise, nanocones and nanodots are formed. This generic nanostructure formation approach does not involve any external material deposition. It is based on a concurrent sputtering, etching, hydrogen termination, and atom/radical redeposition and can be applied to other nanomaterials.
Sensor based on extending the concept of fidelity to classical waves
Authors: Taddese Biniyam Tesfaye , Hart James , Antonsen Thomas M. , Ott Edward , Anlage Steven M.
Published: September 2009

We propose and demonstrate a remote sensor scheme by applying the quantum mechanical concept of fidelity loss to classical waves. The sensor makes explicit use of time-reversal invariance and spatial reciprocity in a wave chaotic system to sensitively and remotely measure the presence of small perturbations. The loss of fidelity is measured through a classical wave analog of the Loschmidt echo by employing a single-channel time-reversal mirror to rebroadcast a probe signal into the perturbed system. We also introduce the use of exponential amplification of the probe signal to partially overcome the effects of propagation losses and to vary the sensitivity.
High performance, high temperature λ≈3.7 μm InGaAs/AlAs(Sb) quantum cascade lasers
Authors: Commin J. P. , Revin D. G. , Zhang S. Y. , Krysa A. B. , Cockburn J. W.
Published: September 2009

We report the development of λ≈3.7 μm strain-compensated InGaAs/AlAs(Sb) quantum cascade lasers operating up to at least 400 K with high peak power and high wall plug efficiency in pulsed regime. We present a detailed comparison of the laser characteristics for devices containing AlAs barriers in the active region with those for devices of identical design but with AlAsSb barriers throughout. The devices with AlAs barriers show significantly superior performance with peak optical power of 2.6 W at 300 K decreasing to 1 W at 400 K, and threshold current densities of 3.3 and 8.2 kA/cm2 at 300 and 400 K, respectively.
Ferromagnetism in Cu-doped AlN films
Authors: Ran Fan-Yong , Subramanian M. , Tanemura Masaki , Hayashi Yasuhiko , Hihara Takehiko
Published: September 2009

AlN films doped with 3.2–8.2 at. % Cu were deposited by helicon magnetron sputtering. The films exhibited ferromagnetism with a Curie temperature above 360 K. The observed magnetic anisotropy and exclusion of ferromagnetic contamination indicated that the ferromagnetism was the intrinsic property of Cu-doped AlN films. Room-temperature (RT) saturation magnetization (Ms) tended to decrease with increasing Cu concentration and the maximum RT Ms obtained was about 8.5 emu/cm3 (0.6 μB/Cu). Vacuum annealing increased the RT Ms values and meanwhile reduced ratio of N/(Al+Cu), which suggested that Al interstitial and N vacancy might contribute to the observed ferromagnetic behavior.
Twin Cu nanowires using energetic beams
Authors: Zhang Yongfeng , Huang Hanchen
Published: September 2009

It is well established that twinning can increase the mechanical strength of metallic (such as Cu) nanowires. This letter proposes a method of introducing twin boundaries into Cu nanowires using energetic beams and demonstrates the feasibility through classical molecular dynamics simulations. The authors show that after electron bombardment twinning occurs in Cu nanowires. The twinning consists of three steps: nucleation of hexagonal-close-packed (HCP) layer, growth of the HCP layer, and interaction of nearby HCP layers. The twinning method reported here offers a mechanism of improving the mechanical strength of metallic nanowires.
The magnetic properties of Bi(Fe0.95Co0.05)O3 ceramics
Authors: Xu Qingyu , Zai Haifa , Wu D. , Qiu T. , Xu M. X.
Published: September 2009

Bi ( Fe 0.95 Co 0.05 ) O 3 bulk ceramics were prepared by rapid sintering using sol-gel derived fine powders. Bi(Fe0.95Co0.05)O3 crystallized in a rhombohedrally distorted BiFeO3 structure with compressive lattice distortion induced by the Co substitution at Fe sites from Raman study. Compared with BiFeO3 prepared under similar conditions, the magnetic properties were significantly enhanced, with saturate magnetization of 1.6 emu/g and remnant magnetization of 0.7 emu/g at 300 K. Clear metamagnetism was observed in Bi(Fe0.95Co0.05)O3.
Site-Specific Cleavage of G-quadruplexes Formed by Oxytricha Telometric Repeats
Authors: Tao Ng Magdeline Tao , Li Xinming , Wang Yifan , Zhou Tianyan , Yang Zhaoqi , Foo Hwee Yun , Li Tianhu
Published: September 2009

We demonstrate that certain G-quadruplex structures formed by Oxytricha telomeric repeats possess DNA-cleavage ability. Further studies verify that this cleavage activity is both site-specific and G-quadruplex-dependent.
Immobilized Whole Cells as Effective Catalysts for Chiral Alcohol Production
Authors: Ng Jeck Fei , Jaenicke Stephan
Published: September 2009

Recombinant Escherichia coli overexpressing the gene LbADH, which encodes for an alcohol dehydrogenase from Lactobacillus brevis, was successfully transformed and cultured. The cells are able to catalyze the reduction of pro-chiral ketones, e.g. ethyl acetoacetate into R-(–)ethyl hydroxybutyrate (EHB) with high conversion and enantiomeric excess >99%. Immobilizing the whole cells in alginate beads leads to a catalyst with improved stability and ease of handling while maintaining the high activity of the free cells. The whole-cell catalyst was tested in a stirred batch reactor (CSTR) and in a continuously operated packed-bed reactor. An Mg2+ concentration of 2 mM was crucial for maintaining the activity of the biocatalyst. After a partial optimization of the process conditions, a productivity of 1.4 gEHB gwcw–1 h–1 could be maintained in a continuous flow reactor over a prolonged period of time.
Fabrication and Field Emission Properties of Poly-CuTAPc Nanowires and Nanotubes
Authors: Gu Feng , Sow Chorng Haur , Xu Guo Qin , Ang Siau Gek
Published: September 2009

Poly-copper tetraaminophthalocyanine (CuTAPc) nanowires and nanotubes were successfully fabricated on porous anodic aluminium oxide (AAO) templates by electropolymerization and characterized. The product of electropolymerization, whether as nanowires or nanotubes, is a function of the monomer concentration and template pore size. The morphology and field emission properties of these nanostructures were studied for investigation of potential application as field emitters. They show interesting turn-on field, maximum current density and enhancement factor, comparable to many other organic nanomaterials.
Phosphorus accumulation by field-grown canola crops and the potential for deep phosphorus placement in a Mediterranean-type climate
Authors: Rose Terry J. , Rengel Zed , Ma Qifu , Bowden John W.
Published: September 2009

When the bulk of phosphorus (P) is located near the soil surface, spring drying of topsoil in Mediterranean-type climates can reduce P availability to crops and cause potential yield loss. In crop species that require a P supply during spring, deep-placement of P fertiliser has proved an effective method of improving P availability and grain yields; however, the spring P demand of field-grown canola (Brassica napus L.) and therefore potential response to deep P placement is not known. This study investigated the effect of deep- (0.17–0.18 m), conventional- (shallow, 0.07–0.08 m), split- (50% deep, 50% shallow), and nil-P fertiliser treatments on P accumulation and seed yields of canola in two field trials. In addition, a glasshouse experiment with different depths of P fertiliser placement and topsoil drying at different growth stages was conducted. In the glasshouse study, deep P placement resulted in greater P uptake by plants, but did not increase seed yields regardless of the time of topsoil drying. At the relatively high-soil-P field site (canola grown on residual P application from the previous year) in a dry season, there was no biomass response to any residual P fertiliser treatments, and P accumulation had ceased by mid flowering. At the low-P field site, P accumulation continued throughout flowering and silique-filling, and seed yields increased significantly (P ≤ 0.05) in the order of split- > deep- > shallow- > nil-P treatments. Improved seed yields in the split- and deep-P treatments appeared to be the direct result of enhanced P availability; in particular, P uptake during vegetative growth (winter) was higher in the treatments with deep P placement. A greater understanding of P accumulation by field-grown canola in relation to soil P properties is needed for better defining optimum P fertiliser placement recommendations.
Incidence and type of cracking in sweet cherry (Prunus avium L.) are affected by genotype and season
Authors: Measham P. F. , Bound S. A. , Gracie A. J. , Wilson S. J.
Published: September 2009

Rain induced fruit cracking in sweet cherries takes 3 distinct forms: stem end cuticular fractures, calyx end cuticular fractures, and large cracks usually deep into the pulp on the cheek of the fruit. A 4-year study of sweet cherry varieties from a commercial orchard in Tasmania, Australia, was conducted to investigate the incidence of crack type and its relative likelihood, as influenced by both genotype and season. Although all 3 crack types developed in the 3-week period before commercial harvest, the extent of cracking was strongly controlled by season. While initial development of cracks coincided with rainfall, no relationship between amount of rain and incidence of cracking was found for crack type. A significant relationship was found between the tangential stress experienced by fruit skin from fruit at harvest maturity and the incidence of cracking recorded in the orchard. No other fruit property (pulp osmotic potential, fruit diameter, weight) explained the differences in incidence of cracking in the field between seasons or varieties. The results suggest that management of cracking needs to consider both varietal and seasonal factors. The development of turgor in maturing fruit also needs further investigation.
Changes in soil mineral nitrogen, nitrogen leached, and surface pH under annual and perennial pasture species
Authors: Dear B. S. , Virgona J. M. , Sandral G. A. , Swan A. D. , Morris S.
Published: September 2009

Soil mineral nitrogen (N) profiles during the growing season and changes in total soil N and available N after 3–4 years were examined under 9 different pasture swards containing annual legumes, lucerne (Medicago sativa L.), or one of 4 perennial grasses at 2 sites representative of the low and medium rainfall belt of south-eastern Australia. The effect of the presence of phalaris (Phalaris aquatica L.) or lucerne on the spatial variation in surface pH was also measured. The 9 pastures were subterranean clover (Trifolium subterraneum L.), subterranean clover with annual weeds, yellow serradella (Ornithopus compressus L.), lucerne, phalaris, cocksfoot (Dactylis glomerata L.), lovegrass (Eragrostis curvula (Schrader) Nees), wallaby grass (Austrodanthonia richardsonii (Cashm.) H.P. Linder), and a mixture of lucerne, phalaris, and cocksfoot. All the perennial treatments were sown with subterranean clover. Available mineral N values in the surface 0.10 m of soil following summer rainfall were substantially higher in pure subterranean clover or serradella (Ornithopus compressus L.) swards (24–50 μg N/g) than those containing a mixture of subterranean clover and perennials (9–20 μg N/g). Apparent leaching of soil nitrate down the profile during winter was greatest in annual pasture treatments and least in swards containing perennials. Soil pH(CaCl2) at the 0–0.10 m depth varied with proximity to perennial plants and was significantly higher (+0.2–1.1 pH units) near the base of perennial plants than in gaps between the perennials or in annual-only swards. Available mineral N to 1.0 m before cropping at the end of the pasture phase was highest following subterranean clover (175–344 kg N/ha) and serradella (202–316 kg N/ha) at both sites. Available N was lowest (91–143 kg N/ha) following perennial grass–clover swards at the drier site where the annual legume content was lower, but perennial grass–clover swards produced larger soil N values (147–219 kg N/ha) at the higher rainfall site. Removal of the pasture in August–September compared with November in the year before cropping increased available N at the time of sowing by an average of 44% (51 kg N/ha) at the drier site and 43% (74 kg N/ha) at the wetter site. Incorporating perennial pasture species in swards was found to be advantageous in reducing nitrate leaching and preventing a decline in surface soil pH; however, available soil N to following crops could be lower if the annual legume content of perennial grass-based pastures declined due to competition from the perennial species.
Growth and phenology of winter wheat and oats in a dual-purpose management system
Authors: Kelman W. M. , Dove H.
Published: September 2009

Dual-purpose cereal cropping is gaining acceptance among growers in mixed farming systems. Success in particular seasons depends on management decisions regarding choice of cereal species, sowing date, timing of grazing, and stocking rate. A more detailed understanding of how these factors influence the growth, phenology, and grain yield of the major cereal forages is needed to model these systems. Wheat (cvv. Whistler and Mackellar) and oats (cv. Blackbutt) were grown under dual-purpose management near Canberra, ACT, over 3 years (2004–06) in 2 crop sequences: wheat-oats-wheat and oats-wheat-wheat. In each year, crops were grazed by sheep at low (20/ha), medium (30–35 /ha), and high (40–52 /ha) grazing intensities. In the pre-grazing periods, measurements of phyllochron interval (PI), tiller development rate (TDR), and stem apex height were made. Post-grazing growth rate was determined from shoot biomass cuts taken at the end of grazing and at grain harvest. Soil moisture changes during each year were monitored to examine the pattern of soil water use under varying grazing intensities. In unusually dry periods in March–April 2004 and 2005, oats established significantly denser plant populations than wheat. In 2004, this initial advantage of oats resulted in greater feed on offer at the start of grazing than wheat, whereas in 2005, higher TDR, lower PI of wheat, and the longer duration of tillering resulted in similar amounts of feed on offer at the start of grazing. Elongation of the stem apex was more rapid in wheat than oats, indicating that wheat would be more at risk of damage during grazing. The post-grazing growth rate of wheat and oats was significantly lower than the ungrazed control in the dry spring years of 2004 and 2006, but significantly higher in the wetter spring year of 2005. While reduction in growth rate at high stocking rate was most likely caused by extreme reduction in leaf area, the causes of increases in growth rate following more lenient grazing require further investigation. In 2004 and 2005, there was no significant difference between crops or between stocking rate treatments in soil water depletion during the post-grazing period. However, in 2006, when soil moisture was not affected by rainfall in the post-grazing period, significantly more water was depleted from soil in the 0.60–1.70 m depth under low and medium stocking rate treatments than under the ungrazed control treatment. A gross margin analysis showed greater economic returns for the dual-purpose compared with a grain-only option in each year, most notably in the very dry season in 2006, when conventional practice would have been to sacrifice the grain crop to grazing or hay production.
Performance of 7 Australian native grasses from the temperate zone under a range of cutting and fertiliser regimes
Authors: Nie Z. N. , Zollinger R. P. , Jacobs J. L.
Published: September 2009

This glasshouse study aimed to examine the performance of 7 Australian native grasses and their responses to different cutting and fertiliser regimes. The 7 native grasses comprised 2 wallaby grasses (Austrodanthonia bipartita cv. Bunderra and Austrodanthonia setacea, Woodhouse ecotype), 2 weeping grasses (Microlaena stipoides cv. Bremmer and ecotype Coleraine), 1 spear grass (Austrostipa mollis, ecotype Lexton), 1 red-leg grass (Bothriochlora macra, ecotype Hamilton), and 1 kangaroo grass (Themeda triandra, ecotype Yass). For each of the 7 grasses, 64 pots each containing 9 plants were arranged in a 4 cutting intensity × 4 fertiliser level factorial design with 4 replicates. The cutting intensity treatments involved (1) cutting to 2 cm at 3–5-week intervals; (2) cutting to 5 cm at 3–5-week intervals; (3) cutting to 10 cm at 3–5-week intervals; and (4) cutting to 2 cm based on leaf stage. The fertiliser regimes included low, medium, and high fertility treatments by applying various rates of phosphorus, and the treatment with addition of compost tea. Herbage accumulation, shoot and root growth, plant survival and tiller density, nutritive characteristics, and leaf stage were monitored. All grass lines produced the lowest herbage mass when cut to 2 cm above ground at 3–5-week intervals. Cutting to 5 cm or to 2 cm based on leaf stage favoured herbage accumulation of Lexton spear grass, Hamilton red grass, Yass kangaroo grass, and Coleraine weeping grass. Cutting to 10 cm favoured herbage accumulation of Bremmer weeping grass and wallaby grass. Cutting to 10 cm together with high fertiliser application considerably increased herbage accumulation in comparison with treatments with low fertiliser application or with compost tea.
Shoot and root biomass were maximised when plants were cut to 10 cm above ground, except Lexton spear grass which had highest root biomass when plants were managed based on leaf stage. Plant survival was dramatically affected by defoliation intensity and varied among species. Plant survival declined when plants were cut to 2 cm above ground for most species. Overall, native grasses were considered to have good nutritive characteristics with crude protein ranging from 17 to 22% and neutral detergent fibre from 48 to 60%.
Results from this study indicate that it may be possible to use leaf stage as a determinant for the commencement of grazing native species. Optimum leaf stages that could be used as a grazing management guide were on average 3.4 for wallaby grass, 4.2 for weeping grass, 3 for spear grass, 3.8 for red-leg grass, and 4.4 for kangaroo grass. However, further work is required to better define this for likely seasonal variation between C3 and C4 species.
pERp1 is significantly up-regulated during plasma cell differentiation and contributes to the oxidative folding of immunoglobulin
Authors: Shimizu Yuichiro , Meunier Laurent , Hendershot Linda M.
Published: September 2009

Plasma cells can synthesize and secrete thousands of Ig molecules per second, which are folded and assembled in the endoplasmic reticulum (ER) and are likely to place unusually high demands on the resident chaperones and folding enzymes. We have discovered a new resident ER protein (pERp1) that is a component of the BiP chaperone complex. PERp1 is substantially up-regulated during B to plasma cell differentiation and can be induced in B cell lines by some UPR activators, arguing that it represents a potentially new class of conditional UPR targets. In LPS-stimulated murine splenocytes, pERp1 interacted covalently via a disulfide bond with IgM monomers and noncovalently with other Ig assembly intermediates. Knockdown and overexpression experiments revealed that pERp1 promoted correct oxidative folding of Ig heavy chains and prevented off-pathway assembly intermediates. Although pERp1 has no homology with known chaperones or folding enzymes, it possesses a thioredoxin-like active site motif (CXXC), which is the signature of oxidoreductases. Mutation of this sequence did not affect its in vivo activity, suggesting that pERp1 is either a unique type of oxidoreductase or a previously unidentified class of molecular chaperone that is dedicated to enhancing the oxidative folding of Ig precursors.
Efficient IgM assembly and secretion require the plasma cell induced endoplasmic reticulum protein pERp1
Authors: van Anken Eelco , Pena Florentina , Hafkemeijer Nicole , Christis Chantal , Romijn Edwin P. , Grauschopf Ulla , Oorschot Viola M. J. , Pertel Thomas , Engels Sander , Ora Ari , Lástun Viorica , Glockshuber Rudi , Klumperman Judith , Heck Albert J. R. , Luban Jeremy , Braakman Ineke
Published: September 2009

Plasma cells daily secrete their own mass in antibodies, which fold and assemble in the endoplasmic reticulum (ER). To reach these levels, cells require pERp1, a novel lymphocyte-specific small ER-resident protein, which attains expression levels as high as BiP when B cells differentiate into plasma cells. Although pERp1 has no homology with known ER proteins, it does contain a CXXC motif typical for oxidoreductases. In steady state, the CXXC cysteines are locked by two parallel disulfide bonds with a downstream C(X)
6
C motif, and pERp1 displays only modest oxidoreductase activity. pERp1 emerged as a dedicated folding factor for IgM, associating with both heavy and light chains and promoting assembly and secretion of mature IgM.
Identification of tumor-initiating cells in a highly aggressive brain tumor using promoter activity of nucleostemin
Authors: Tamase Akira , Muraguchi Teruyuki , Naka Kazuhito , Tanaka Shingo , Kinoshita Masashi , Hoshii Takayuki , Ohmura Masako , Shugo Haruhiko , Ooshio Takako , Nakada Mitsutoshi , Sawamoto Kazunobu , Onodera Masafumi , Matsumoto Kunio , Oshima Masanobu , Asano Masahide , Saya Hideyuki , Okano Hideyuki , Suda Toshio , Hamada Jun-ichiro , Hirao Atsushi
Published: September 2009

Controversy remains over whether the cancer stem cell (CSC) theory applies to all tumors. To determine whether cells within a highly aggressive solid tumor are stochastically or hierarchically organized, we combined a reporter system where the nucleostemin (NS) promoter drives GFP expression (termed NS-GFP) with a mouse brain tumor model induced by retroviral Ras expression on a p16

Ink4a

/p19

Arf

-deficient background. The NS-GFP system allowed us to monitor the differentiation process of normal neural stem/precursor cells by analyzing GFP fluorescence intensity. In tumor-bearing mice, despite the very high frequency of tumorigenic cells, we successfully identified the NS-GFP
+
cells as tumor-initiating cells (T-ICs). The clonal studies conclusively established that phenotypical heterogeneity can exist among the cells comprising a genetically homogeneous tumor, suggesting that this aggressive brain tumor follows the CSC model. Detailed analyses of the NS-GFP
+
brain tumor cells revealed that T-ICs showed activation of the receptor tyrosine kinase c-Met, which functions in tumor invasiveness. Thus, the NS-GFP system provides a powerful tool to elucidate stem cell biology in normal and malignant tissues.
Fast screening of protein surfaces using geometric invariant fingerprints
Authors: Yin Shuangye , Proctor Elizabeth A. , Lugovskoy Alexey A. , Dokholyan Nikolay V.
Published: September 2009

We develop a rapid and efficient method for the comparison of protein local surface similarities using geometric invariants (fingerprints). By combining fast fingerprint comparison with explicit alignment, we successfully screen the entire Protein Data Bank for proteins that possess local surface similarities. Our method is independent of sequence and fold similarities, and has potential application to protein structure annotation and protein-protein interface design.