bluuebunny/crossref_metadata_2025 huggingface dataset:
Local Sociotechnical System Development in the NHS National Programme for Information Technology
Authors: Eason Ken
Published: June 2007

The National Programme for Information Technology is implementing standard electronic healthcare systems across the National Health Service Trusts in England. This paper reports the responses of the Trusts and their healthcare teams to the applications in the programme as they are being implemented. It concludes that, on the basis of the data available, it is likely that the emergent behaviour of healthcare staff will serve to minimise the impact of the systems. The paper looks at the opportunities within the programme to undertake local sociotechnical system design to help staff exploit the opportunities of the new electronic systems. It concludes that there are opportunities and offers one case study example in a Mental Health Trust. However, it concludes that there are many aspects of the technical systems themselves and also of the approach to implementation, that limit the opportunities for local sociotechnical systems design work.
Interfaces in semiconductor/metal radial superlattices
Authors: Deneke Christoph , Sigle Wilfried , Eigenthaler Ulrike , van Aken Peter A. , Schütz Gisela , Schmidt Oliver G.
Published: June 2007

Semiconductor/metal radial superlattices are produced by the roll-up of inherently strained InGaAs∕Ti∕Au as well as InAlGaAs∕GaAs∕Cr films. Cross sections of the obtained structures are prepared and investigated in detail by diverse transmission electron microscopy as well as microanalysis techniques. Special attention is paid to the interfaces of the semiconductor/metal hybrid superlattice. The study reveals amorphous, noncrystalline layers for the semiconductor/metal as well as for the metal/semiconductor interface. The chemical analysis suggests that the observed interlayers are oxides giving rise to a semiconductor/oxide/metal/oxide superlattice rather than a pure semiconductor/metal superlattice.
Development of a three-degree-of-freedom laser linear encoder for error measurement of a high precision stage
Authors: Huang Hsueh-Liang , Liu Chien-Hung , Jywe Wen-Yuh , Wang Ming-Shi , Fang Te-Hua
Published: June 2007

In this study, a laser linear encoder with three degrees of freedom (3-DOFs) based on diffraction and interference was developed to measure the linear displacement and two angular errors of a linear moving stage. Parts of the linear motion errors induced from the two angular errors can be calculated by this prototype 3-DOF laser encoder. It was an effective method for online error calculation and compensation to improve precision stage performance. This new function was superior to other laser encoders. The verification results showed that the resolution is 20nm. It detected displacements relative to an external grating scale with accuracy of about ±150nm for a measuring range of ±1mm, and detected the angular errors with related accuracy of about ±1arcsec for a measuring range of ±100arcsec.
Adsorption of molecular hydrogen and hydrogen sulfide on Au clusters
Authors: Ghebriel Hagos W. , Kshirsagar Anjali
Published: June 2007

The authors present theoretical results describing the adsorption of H2 and H2S molecules on small neutral and cationic gold clusters (Aun(0∕+), n=1–8) using density functional theory with the generalized gradient approximation. Lowest energy structures of the gold clusters along with their isomers are considered in the optimization process for molecular adsorption. The adsorption energies of H2S molecule on the cationic clusters are generally greater than those on the corresponding neutral clusters. These are also greater than the H2 adsorption energies on the corresponding cationic and neutral clusters. The adsorption energies for cationic clusters decrease with increasing cluster size. This fact is reflected in the elongations of the Au–S and Au–H bonds indicating weak adsorption as the cluster grows. In most cases, the geometry of the lowest energy gold cluster remains planar even after the adsorption. In addition, the adsorbed molecule gets adjusted such that its center of mass lies on the plane of the gold cluster. Study of the orbital charge density of the gold adsorbed H2S molecule reveals that conduction is possible through molecular orbitals other than the lowest unoccupied molecular orbital level. The dissociation of the cationic AunSH2+ cluster into AunS+ and H2 is preferred over the dissociation into AumSH2+ and Aun−m, where n=2–8 and m=1−(n−1). H2S adsorbed clusters with odd number of gold atoms are more stable than neighboring even n clusters.
Method of generating and measuring static small force using down-slope component of gravity
Authors: Fujii Yusaku
Published: June 2007

A method of generating and measuring static small forces at the micro-Newton level is proposed. In the method, the down-slope component of gravity acting on a mass on an inclined plane is used as a static force. To realize a linear motion of the mass with a small friction, an aerostatic linear bearing is used. The forces acting on the mass, such as the down-slope component of gravity and the dynamic frictional force, are determined by the levitation mass method. In an experiment, a static small force of approximately 183μN is generated and measured with a standard uncertainty of approximately 2μN.
Basic antenna transmitting characteristics using an extrapolation range measurement technique at a millimeter-wave band at NMIJ/AIST
Authors: Yamamoto Tetsuya
Published: June 2007

A novel test fixture operating at a millimeter-wave band using an extrapolation range measurement technique was developed at the National Metrology Institute of Japan (NMIJ). Here I describe the measurement system using a Q-band test fixture. I measured the relative insertion loss as a function of antenna separation distance and observed the effects of multiple reflections between the antennas. I also evaluated the antenna gain at 33GHz using the extrapolation technique.
Growth mechanisms of amorphous SiOx nanowires
Authors: Aharonovich Igor , Lifshitz Yeshayahu , Tamir Shoshana
Published: June 2007

Amorphous SiOx nanowires (NWs) 10–50nm thick and tens of microns long were grown by laser ablation of silicon containing targets onto different substrates held at elevated temperatures. The influence of the growth parameters on the NWs growth and structure was studied. Deposition of a metal catalyst on the substrates was found essential for the SiOx NW growth. The morphology and structure of the NWs were studied using high resolution scanning and transmission electron microscopes with their accessories. Possible growth mechanisms of these nanowires were suggested and discussed.
Ultrathin organic transistors for chemical sensing
Authors: Yang Richard D. , Gredig T. , Colesniuc Corneliu N. , Park Jeongwon , Schuller Ivan K. , Trogler William C. , Kummel Andrew C.
Published: June 2007

Ultrathin cobalt phthalocyanine transistors of 4 ML have been fabricated for chemical sensing. Compared to 50 ML devices, the ultrathin transistors show faster response times, higher base line stabilities, and sensitivity enhancements of 1.5–20 for the five analytes tested. The enhanced response for the ultrathin transistors provides insight into the device physics. The absorption of analytes changes the surface doping level and trap energies. The changes in surface trap energies perturb the charge transport properties of the ultrathin devices, thereby, making these devices more sensitive.
Charge carrier compensation effect in Ti doped La2−xSrxCuO4 system: Resistivity and infrared spectra study
Authors: Wang Caixia , Sun Yuping , Zhang Yuheng
Published: June 2007

The infrared spectra and resistivity of La1.85Sr0.15Cu1−yTiyO4 (0⩽y⩽0.06) and La2−xSrxCu0.94Ti0.06O4 (0.15⩽x⩽0.31) samples are studied. It is found that the resistivities of La1.85Sr0.15Cu1−yTiyO4 samples are larger than that of La2−xSrxCu0.94Ti0.06O4 samples. Especially, in the vicinity of the superconducting transition temperature (Tc∼37.8K) of La1.85Sr0.15CuO4, the resistivity for the end composition compound La1.85Sr0.15Cu0.94Ti0.06O4 is about two orders of magnitude higher than that for compound La2−xSrxCu0.94Ti0.06O4 with x=0.16. Two infrared transmission peaks located at ν1=503cm−1 and ν2=680cm−1 are assigned to the stretching mode of apical oxygen atoms out of Cu–O plane and the stretching mode of oxygen atoms in Cu–O plane, respectively. The results indicate that the appearance of the ν2 peak for La1.85Sr0.15Cu1−yTiyO4 series samples and the disappearance of ν2 peak for La2−xSrxCu0.94Ti0.06O4 series samples are always related to the change of the hole carrier concentration in the two systems. The observed phenomena are discussed from the viewpoint of the charge carrier compensation effect.
Gain bandwidth of NbN hot-electron bolometer terahertz mixers on 1.5μm Si3N4∕SiO2 membranes
Authors: Cherednichenko S. , Drakinskiy V. , Baubert J. , Krieg J.-M. , Voronov B. , Gol’tsman G. , Desmaris V.
Published: June 2007

The gain bandwidth of NbN hot-electron bolometer terahertz mixers on electrically thin Si3N4∕SiO2 membranes was experimentally investigated and compared with that of HEB mixers on bulk substrates. A gain bandwidth of 3.5GHz is achieved on bulk silicon, whereas the gain bandwidth is reduced down to 0.6–0.9GHz for mixers on 1.5μm Si3N4∕SiO2 membranes. We show that application of a MgO buffer layer on the membrane extends the gain bandwidth to 3GHz. The experimental data were analyzed using the film-substrate acoustic mismatch approach.
A miniature electrothermal thruster using microwave-excited microplasmas: Thrust measurement and its comparison with numerical analysis
Authors: Takao Yoshinori , Eriguchi Koji , Ono Kouichi
Published: June 2007

A microplasma thruster has been developed, consisting of a cylindrical microplasma source 10mm long and 1.5mm in inner diameter and a conical micronozzle 1.0–1.4mm long with a throat of 0.12–0.2mm in diameter. The feed or propellant gas employed is Ar at pressures of 10–100kPa, and the surface-wave-excited plasma is established by 4.0GHz microwaves at powers of <10W. The thrust has been measured by a combination of target and pendulum methods, exhibiting the performance improved by discharging the plasma. The thrust obtained is 1.4mN at an Ar gas flow rate of 60SCCM (1.8mg∕s) and a microwave power of 6W, giving a specific impulse of 79s and a thrust efficiency of 8.7%. The thrust and specific impulse are 0.9mN and 51s, respectively, in cold-gas operation. A comparison with numerical analysis indicates that the pressure thrust contributes significantly to the total thrust at low gas flow rates, and that the micronozzle tends to have an isothermal wall rather than an adiabatic.
Comparison study of catalyst nanoparticle formation and carbon nanotube growth: Support effect
Authors: Wang Yunyu , Luo Zhiquan , Li Bin , Ho Paul S. , Yao Zhen , Shi Li , Bryan Eugene N. , Nemanich Robert J.
Published: June 2007

A comparison study has been conducted on the formation of catalyst nanoparticles on a high surface tension metal and low surface tension oxide for carbon nanotube (CNT) growth via catalytic chemical vapor deposition (CCVD). Silicon dioxide (SiO2) and tantalum have been deposited as supporting layers before deposition of a thin layer of iron catalyst. Iron nanoparticles were formed after thermal annealing. It was found that densities, size distributions, and morphologies of iron nanoparticles were distinctly different on the two supporting layers. In particular, iron nanoparticles revealed a Volmer-Weber growth mode on SiO2 and a Stranski-Krastanov mode on tantalum. CCVD growth of CNTs was conducted on iron∕tantalum and iron∕SiO2. CNT growth on SiO2 exhibited a tip growth mode with a slow growth rate of less than 100nm∕min. In contrast, the growth on tantalum followed a base growth mode with a fast growth rate exceeding 1μm∕min. For comparison, plasma enhanced CVD was also employed for CNT growth on SiO2 and showed a base growth mode with a growth rate greater than 2μm∕min. The enhanced CNT growth rate on tantalum was attributed to the morphologies of iron nanoparticles in combination with the presence of an iron wetting layer. The CNT growth mode was affected by the adhesion between the catalyst and support as well as CVD process.
Size and shape of supported zirconia nanoparticles determined by x-ray photoelectron spectroscopy
Authors: Yubero F. , Mansilla C. , Ferrer F. J. , Holgado J. P. , González-Elipe A. R.
Published: June 2007

The initial stages of growth of zirconia nanoparticles deposited on SiO2, Y2O3, and CeO2 substrates have been studied by the x-ray photoelectron spectroscopy peak shape analysis. ZrO2 was deposited by plasma decomposition of a volatile Zr(OtBu)4 precursor. The electronic interactions at each particular interface formed have been followed by means of the modified Auger parameter of the deposited Zr cations. They were quantified by means of Wagner plots and the chemical state vectors of the systems. The observed changes in these local electronic probes as the amount of deposit was increased have been correlated to the particular ZrO2 nanostructures identified on each substrate considered. A Volmer-Weber (islands) growth mechanism has been found for all the substrates considered. Moreover, clear indications have been found of a columnar growth for the case of ZrO2 deposited on SiO2.
Effects of anchoring strength on diffraction properties of liquid crystal phase gratings formed on photoalignment polymer films
Authors: Ono Hiroshi , Oikawa Shinji , Kawatsuki Nobuhiro
Published: June 2007

The liquid crystal phase gratings were prepared using a polarization holographic exposure on poly(vinyl cinnamate) or photocross-linkable polymer liquid crystal (PCLC) films. Anchoring strength between the photoalignment layer and low-molar-mass liquid crystal is a very important role to realize the liquid crystal grating as a practical optical device. Anchoring strength of our PCLC film is sufficiently strong and optical properties of liquid crystal gratings were theoretically well explained assuming the strong anchoring.
Mechanism for radiative recombination in ZnCdO alloys
Authors: Buyanova I. A. , Bergman J. P. , Pozina G. , Chen W. M. , Rawal S. , Norton D. P. , Pearton S. J. , Osinsky A. , Dong J. W.
Published: June 2007

Temperature dependent cw- and time-resolved photoluminescence combined with absorption measurements are employed to evaluate the origin of radiative recombination in ZnCdO alloys grown by molecular-beam epitaxy. The near-band-edge emission is attributed to recombination of excitons localized within band tail states likely caused by nonuniformity in Cd distribution. Energy transfer between the tail states is argued to occur via tunneling of localized excitons. The transfer is shown to be facilitated by increasing Cd content due to a reduction of the exciton binding energy and, therefore, an increase of the exciton Bohr radius in the alloys with a high Cd content.
Defect mode lasing from a double-layered dye-doped polymeric cholesteric liquid crystal films with a thin rubbed defect layer
Authors: Jeong Soon Moon , Ha Na Young , Takanishi Yoichi , Ishikawa Ken , Takezoe Hideo , Nishimura Suzushi , Suzaki Goro
Published: June 2007

The authors have demonstrated defect mode lasing emission from a spin-coated double-layered dye-doped polymeric cholesteric liquid crystal (PCLC) films with a thin rubbed isotropic layer in between. The rubbed layer acts not only as an alignment layer for the second PCLC layer but also as an isotropic defect layer breaking periodicity of PCLC films. All the processes can be achieved in a wet process. Because of the process, the present polymeric solid-state laser is available as a freestanding thin film of only 5.5μm in thickness and an almost limitless large area, which enable one to use it as a disposable laser chip of any shapes.
Ambipolar field-effect transistor based on organic-inorganic hybrid structure
Authors: Nakanotani Hajime , Yahiro Masayuki , Adachi Chihaya , Yano Koki
Published: June 2007

The authors developed an ambipolar field-effect transistor (FET) based on an organic-inorganic hybrid structure that consisted of an indium zinc oxide and pentacene double layer fabricated on a SiO2∕n++-Si substrate. Although the FETs based on an indium zinc oxide or pentacene single layer only showed unipolar FET characteristics, the hybrid FET showed definite ambipolar FET characteristics. The authors obtained a highly saturated field-effect hole and electron mobilities of 0.14 and 13.8cm2∕Vs. Furthermore, the authors demonstrated electroluminescence from hybrid FETs using tetracene as an emitting layer. The authors’ success shows that the hybridization of organic and inorganic materials opens up a new field in electronics.
Facile assembling of gold nanorods with large aspect ratio and their surface-enhanced Raman scattering properties
Authors: Kawamura Go , Yang Yong , Nogami Masayuki
Published: June 2007

Linear- and parallel-aligned gold nanorods (GNRs) were self-assembled on glass substrates and their surface-enhanced Raman scattering effect was investigated. GNRs were prepared by seed-mediated growth method and self-assembled to form linear and parallel aggregation on the substrate. The parallel-aligned GNRs showed weak optical absorption intensities in the visible to infrared wavelength region. On the other hand, the linear-aligned GNRs exhibited strong optical absorption bands peaking at 830 and 2200nm, which are assigned to the weakly coupled surface plasmons of the GNRs. When Rhodamine-6G molecules were adsorbed on the linear-aligned GNRs, strong surface-enhanced Raman scattering spectra were observed.
Formation of a one-dimensional grating at the molecular scale by self-assembly of straight silicon nanowires
Authors: Sahaf H. , Masson L. , Léandri C. , Aufray B. , Le Lay G. , Ronci F.
Published: June 2007

Upon submonolayer deposition of silicon onto the anisotropic silver (110) surface flat lying individual Si nanowires, all oriented along the [−110] direction, can be grown at room temperature with a high aspect ratio. Upon deposition at ∼200°C, these one-dimensional nanostructures self-assemble by lateral compaction to form a regular array of essentially identical nanowires, ∼1.6nm in width, covering uniformly the entire substrate surface. They realize, at macroscopic sizes, a highly perfect one-dimensional grating with a molecular-scale pitch of just 2nm.
Hybrid AlN–SiC deep ultraviolet Schottky barrier photodetectors
Authors: Dahal R. , Al Tahtamouni T. M. , Fan Z. Y. , Lin J. Y. , Jiang H. X.
Published: June 2007

Deep ultraviolet (DUV) Schottky barrier photodetectors have been demonstrated by exploiting the epitaxial growth of high quality AlN epilayer on n-type SiC substrate. The fabricated AlN∕n-SiC hybrid Schottky barrier detectors exhibited a peak responsivity at 200nm with very sharp cutoff wavelength at 210nm, very high reverse breakdown voltages (>200V), very low dark currents (about 10fA at a reverse bias of 50V), and high responsivity and DUV to UV/visible rejection ratio. These outstanding features are direct attributes of the fundamental material properties and high quality of AlN epilayers. The fabricated photodetectors also have a thermal energy limited detectivity at zero bias of about 1.0×1015cmHz1∕2W−1. These results demonstrated that AlN epilayers are an excellent candidate as an active material for DUV optoelectronic device applications.
Large magnetic entropy change in Ni50Mn50−xInx Heusler alloys
Authors: Pathak Arjun Kumar , Khan Mahmud , Dubenko Igor , Stadler Shane , Ali Naushad
Published: June 2007

The magnetocaloric properties of polycrystalline Ni50Mn50−xInx (15⩽x⩽16) associated with the second order magnetic transition at the Curie temperature and the first order martensitic transition were studied using magnetization measurements. The refrigeration capacity and magnetic entropy change were found to depend on the In concentration and reach a maximum value of refrigeration capacity of 280J∕kg with a magnetic entropy change of −6.8J∕kgK at 318K for a magnetic field change of 5T. These values of the magnetocaloric parameters are comparable to that of the largest values reported near the second order transition of metallic magnets near room temperature.
Improvements in the device characteristics of amorphous indium gallium zinc oxide thin-film transistors by Ar plasma treatment
Authors: Park Jin-Seong , Jeong Jae Kyeong , Mo Yeon-Gon , Kim Hye Dong , Kim Sun-Il
Published: June 2007

The effect of Ar plasma treatment on amorphous indium gallium zinc oxide (a-IGZO) thin films was investigated. The net electron carrier concentration (1020–1021cm−3) of the a-IGZO thin films dramatically increased upon their exposure to the Ar plasma compared to that (1014cm−3) of the as-deposited thin film. The authors attempted to reduce the contact resistance between the Pt∕Ti (source/drain electrode) and a-IGZO (channel) by using the Ar plasma treatment. Without the treatment, the a-IGZO thin film transistors (TFTs) with W∕L=50∕4μm exhibited a moderate field-effect mobility (μFE) of 3.3cm2∕Vs, subthreshold gate swing (S) of 0.25V∕decade, and Ion∕off ratio of 4×107. The device performance of the a-IGZO TFTs was significantly improved by the Ar plasma treatment. As a result, an excellent S value of 0.19V∕decade and high Ion∕off ratio of 1×108, as well as a high μFE of 9.1cm2∕Vs, were achieved for the treated a-IGZO TFTs.
Wheat stripe rust in China
Authors: Wan A. M. , Chen X. M. , He Z. H.
Published: June 2007

China has the largest stripe rust epidemic region in the world in terms of wheat acreage affected by the disease. Extensive studies on the epidemiology and management of stripe rust have been carried out since the widespread occurrence of the disease in the 1950s. Fifteen epidemic zones were classified, based on factors influencing the occurrence of wheat stripe rust. The disease can spread inter-regionally, mainly from west to east and from south to north. Winter-wheat growing regions in the north-west, south-west, and north, and spring-wheat growing regions in the north-west are the major epidemic areas. Hotspots of wheat stripe rust are mainly located in south-eastern Gansu and north-western Sichuan, and these areas constitute the inoculum base, centre of diversity, and major over-summering areas of the pathogen. Successful control in over-summering areas is the key to achieving sustainable management of stripe rust in China. Pathogen variability and race virulence have been monitored continuously, and the resistance genetics and background of Chinese wheat cultivars analysed. Effective management of stripe rust includes resistance breeding and application, diversification and deployment of various resistance genes, use of chemicals, adoption of appropriate agricultural practice, and integrated disease management in ‘hotspot’ regions. Collaboration of scientists among various organisations and disciplines is vital. We discuss the progress and challenges of wheat stripe rust management in China.
Appearance of atypical Puccinia striiformis f. sp. tritici phenotypes in north-western Europe
Authors: Hovmøller Mogens S. , Justesen Annemarie F.
Published: June 2007

A combination of large-scale cultivation of highly susceptible cultivars and mild winters caused severe yield losses due to yellow rust in NW Europe in the early 1990s, but in recent years the disease has become less predominant. Several atypical Puccinia striiformis f. sp. tritici pathotypes have been observed in recent years, showing virulence spectra which made them able only to infect cultivars covering less than 5% of the wheat and triticale area in Denmark. Some were even unable to grow on any of the standard ‘European’ and ‘World’ yellow rust differentials. We observed 2 distinct groups of atypical pathotypes, each subdividing into 2 highly divergent AFLP phenotypes. It was striking that AFLP diversity among unusual pathotypes, sampled within a short time period in a small area on very few host cultivars, which induced limited or no selection on the pathogen population, was 3–4 times higher than among isolates sampled from a large number of cultivars with different Yr-genes in 4 different countries during more than 25 years. The repeated occurrence of atypical phenotypes of diverse origin may suggest a more frequent and even more distant dispersal of P. striiformis uredospores than previously anticipated. Finally, the disease reactions conferred by these unusual types on a wide range of differentials were used to discuss the limits for a genetic interpretation in terms of assessment of virulence and avirulence in pathogen isolates.
Wheat rust resistance research at CSIRO
Authors: Ellis Jeffrey G. , Mago Rohit , Kota Raja , Dodds Peter N. , McFadden Helen , Lawrence Greg , Spielmeyer Wolfgang , Lagudah Evans
Published: June 2007

Although chemical control is available for rust diseases in wheat, economic and environmental factors favour genetic solutions. Maintenance and improvement of levels of resistance and durability of the genetic control of the 3 wheat rust diseases will occur with the application of DNA markers for pyramiding resistance genes. Information about the molecular basis of rust resistance, including durable, adult-plant resistance, coming from studies in model species such as flax and flax rust and from studies of wheat and barley, will provide knowledge for new biotechnological approaches to rust resistance. Increasing cereal gene sequence data will improve the efficiency of cloning disease resistance genes and, together with the rapid progress in understanding the molecular basis of rust resistance, will make it possible to construct transgenic plants with multiple rust resistance genes at a single locus, which will provide efficient breeding and increased durability of rust resistance.
Challenges and solutions for stripe rust control in the United States
Authors: Chen X. M.
Published: June 2007

Stripe rust of wheat, caused by Puccinia striiformis f. sp. tritici, has been one of the most destructive diseases on wheat in the western USA since the late 1950s and has become increasingly important in the central and south-eastern USA since 2000. Stripe rust of barley, caused by P. striiformis f. sp. hordei, a relatively new disease, has established and caused severe damage in the south-central and western states since the pathogen was first reported in Texas in 1991. Stripe rusts of wheat and barley have been monitored by trap nurseries and by field surveys. Collections of stripe rust from wheat, barley, triticale, and grasses have been tested on a set of 20 wheat differential genotypes for identifying races of P. striiformis f. sp. tritici and a set of 12 barley differential genotypes for identifying races of P. striiformis f. sp. hordei. In total, 62 new races of P. striiformis f. sp. tritici and 22 new races of P. striiformis f. sp. hordei have been identified since 2000. Germplasm and breeding lines of wheat and barley have been tested every year under natural infection in the field and with selected races in the greenhouse. Combinations of durable high-temperature, adult-plant resistance with effective all-stage resistance should provide more effective stripe rust control and reduce the use of fungicides.
New sources of rust resistance from alien species: meliorating linked defects and discovery
Authors: Dundas I. S. , Anugrahwati D. R. , Verlin D. C. , Park R. F. , Bariana H. S. , Mago R. , Islam A. K. M. R.
Published: June 2007

This paper presents a review of projects undertaken over the past 2 decades aimed at improving the yield and/or quality attributes of translocation lines carrying rust resistance genes from species related to wheat, so as to make these lines more suitable for use in breeding programs. Homeologous recombination between the alien chromosome segments and normal wheat chromosomes was induced in a ph1bph1b background. Lines with shortened alien chromatin were selected using dissociation patterns of molecular-based markers. A new line of bread wheat was developed containing a shortened chromosome 1RS segment carrying rust resistance gene SrR (Secale cereale L.), in which a defect affecting dough-quality appears to have been deleted. In addition, several advanced lines were produced with modified 6Ae#1L chromosome segments with Sr26 (Thinopyrum ponticum), 2S#1 chromosome segments with Sr32, and a previously unnamed gene, a 2S#2 chromosome segment with Sr39 (Triticum speltoides), 4G#1 chromosome segments with Sr37, and 2G#2 chromosome segments with Sr40 (T. timopheevii).
Self-vaccination by methamphetamine glycation products chemically links chronic drug abuse and cardiovascular disease
Authors: Treweek Jennifer , Wee Sunmee , Koob George F. , Dickerson Tobin J. , Janda Kim D.
Published: June 2007

Methamphetamine abuse is spreading rapidly throughout the United States and is characterized by significant health consequences. The powerfully rewarding effects of methamphetamine are attributed to multiple neuropharmacological actions such as its ability to block plasma membrane transporters of all monoamines, reduce dopamine transporter expression, and inhibit monoamine oxidase activity while increasing tyrosine hydroxylase activity. However, subsequent neuroreceptor changes including monoamine deficits complement this striking increase in monoamine release. Chronic methamphetamine abuse, as studied via self-administration paradigms in rodents, causes progressive dopaminergic neurotoxicity, a neuroanatomical change accompanied by increasing drug tolerance and escalating intake, two behavioral parameters of addiction. We have recently proposed that methamphetamine covalently glycates endogenous proteins. Such an event spurs antibody production against these immunoconjugates, possibly leading to drug sequestration by antibody binding of drug. Here we demonstrate that this drug-dependent glycation mechanism is operativein vivothrough the dose-dependent detection of antibodies against methamphetamine-derived advanced glycation end products in rats chronically self-administering methamphetamine. Furthermore, increased levels of proinflammatory cytokines, evidence of potent immunoactivation, were also detected. Given the known role of advanced glycation end products in the alteration of protein functionin vivoand the participation of these molecules in various diseases, methamphetamine-derived advanced glycation end products provide an unrecognized molecular mechanism for the development of vasculitis and other cardiovascular maladies reported with high incidence in chronic methamphetamine users.
Electron tunneling through alkanedithiol self-assembled monolayers in large-area molecular junctions
Authors: Akkerman Hylke B. , Naber Ronald C. G. , Jongbloed Bert , van Hal Paul A. , Blom Paul W. M. , de Leeuw Dago M. , de Boer Bert
Published: June 2007

The electrical transport through self-assembled monolayers of alkanedithiols was studied in large-area molecular junctions and described by the Simmons model [Simmons JG (1963)
J Appl Phys
34:1793–1803 and 2581–2590] for tunneling through a practical barrier, i.e., a rectangular barrier with the image potential included. The strength of the image potential depends on the value of the dielectric constant. A value of 2.1 was determined from impedance measurements. The large and well defined areas of these molecular junctions allow for a simultaneous study of the capacitance and the tunneling current under operational conditions. Electrical transport for octanedithiol through tetradecanedithiol self-assembled monolayers up to 1 V can simultaneously be described by a single effective mass and a barrier height. There is no need for additional fit constants. The barrier heights are in the order of 4–5 eV and vary systematically with the length of the molecules. Irrespective of the length of the molecules, an effective mass of 0.28 was determined, which is in excellent agreement with theoretical predictions.
The Nedd4-binding partner 1 (N4BP1) protein is an inhibitor of the E3 ligase Itch
Authors: Oberst Andrew , Malatesta Martina , Aqeilan Rami I. , Rossi Mario , Salomoni Paolo , Murillas Rodolfo , Sharma Prashant , Kuehn Michael R. , Oren Moshe , Croce Carlo M. , Bernassola Francesca , Melino Gerry
Published: June 2007

Nedd4-binding partner-1 (N4BP1) has been identified as a protein interactor and a substrate of the homologous to E6AP C terminus (HECT) domain-containing E3 ubiquitin–protein ligase (E3), Nedd4. Here, we describe a previously unrecognized functional interaction between N4BP1 and Itch, a Nedd4 structurally related E3, which contains four WW domains, conferring substrate-binding activity. We show that N4BP1 association with the second WW domain (WW2) of Itch interferes with E3 binding to its substrates. In particular, we found that N4BP1 and p73α, a target of Itch-mediated ubiquitin/proteasome proteolysis, share the same binding site. By competing with p73α for binding to the WW2 domain, N4BP1 reduces the ability of Itch to recruit and ubiquitylate p73α and inhibits Itch autoubiquitylation activity both in
in vitro
and
in vivo
ubiquitylation assays. Similarly, both c-Jun and p63 polyubiquitylation by Itch are inhibited by N4BP1. As a consequence, genetic and RNAi knockdown of N4BP1 diminish the steady-state protein levels and significantly impair the transcriptional activity of Itch substrates. Notably, stress-induced induction of c-Jun was impaired in
N4BP1
−/−
cells. These results demonstrate that N4BP1 functions as a negative regulator of Itch. In addition, because inhibition of Itch by N4BP1 results in the stabilization of crucial cell death regulators such as p73α and c-Jun, it is conceivable that N4BP1 may have a role in regulating tumor progression and the response of cancer cells to chemotherapy.
Ultradian oscillations of Stat, Smad, and Hes1 expression in response to serum
Authors: Yoshiura Shigeki , Ohtsuka Toshiyuki , Takenaka Yoshiko , Nagahara Hiroki , Yoshikawa Kenichi , Kageyama Ryoichiro
Published: June 2007

Serum response has been used as a model for studying signaling transduction for many biological events such as cell proliferation and survival. Although expression of many genes is up- or down-regulated after serum stimulation, the Notch effector
Hes1
displays oscillatory response. However, the precise mechanism and biological significance of this oscillation remain to be determined. Here, we identified serum-induced ultradian oscillators, including molecules in Stat and Smad signaling. Stat and Smad oscillations involve activation of Stat3 and Smad1 and delayed negative feedback by their inhibitors Socs3 and Smad6, respectively. Moreover, Stat oscillations induce oscillatory expression of Hes1 by regulating its half-life, and loss of Hes1 oscillations leads to G
1
phase retardation of the cell cycle. These results indicate that coupled Stat and Hes1 oscillations are important for efficient cell proliferation and provide evidence that expression modes of signaling molecules affect downstream cellular events.
Csrp1 regulates dynamic cell movements of the mesendoderm and cardiac mesoderm through interactions with Dishevelled and Diversin
Authors: Miyasaka Kota Y. , Kida Yasuyuki S. , Sato Takayuki , Minami Mari , Ogura Toshihiko
Published: June 2007

Zebrafish Csrp1 is a member of the cysteine- and glycine-rich protein (CSRP) family and is expressed in the mesendoderm and its derivatives. Csrp1 interacts with Dishevelled 2 (Dvl2) and Diversin (Div), which control cell morphology and other dynamic cell behaviors via the noncanonical Wnt and JNK pathways. When
csrp1
message is knocked down, abnormal convergent extension cell movement is induced, resulting in severe deformities in midline structures. In addition, cardiac bifida is induced as a consequence of defects in cardiac mesoderm cell migration. Our data highlight Csrp1 as a key molecule of the noncanonical Wnt pathway, which orchestrates cell behaviors during dynamic morphogenetic movements of tissues and organs.
Enteroendocrine precursors differentiate independently of Wnt and form serotonin expressing adenomas in response to active β-catenin
Authors: Wang Yang , Giel-Moloney Maryann , Rindi Guido , Leiter Andrew B.
Published: June 2007

Wnt signaling is required for the maintenance of intestinal stem cells and self-renewal of the intestinal epithelium. Intestinal cancers are frequently associated with mutations that activate the Wnt pathway. The role of Wnt signaling on differentiation of lineage-specific precursors in the intestine is not well characterized. Here, we show that specification of enteroendocrine but not Paneth cells occurs independently of Wnt signals by conditional deletion of β-catenin in immature cells expressing the transcription factor, neurogenin 3. In addition, we determined whether neurogenin 3-expressing cells respond to abnormal Wnt signaling. Activation of the Wnt pathway by conditionally deleting exon 3 of the β-catenin gene at an early stage of enteroendocrine cell differentiation induced small-intestinal adenomas expressing serotonin, a feature not previously described in other tumors induced by Wnt in mice. In contrast, excision of exon 3 of β-catenin at a later stage of enteroendocrine differentiation did not produce tumors. These results provide direct evidence that some intestinal lineages are specified independently of the Wnt pathway and may lead to a better understanding of the spectrum of neuroendocrine differentiation frequently seen in human gastrointestinal cancer.
Mechanisms of host cell exit by the intracellular bacteriumChlamydia
Authors: Hybiske Kevin , Stephens Richard S.
Published: June 2007

The mechanisms that mediate the release of intracellular bacteria from cells are poorly understood, particularly for those that live within a cellular vacuole. The release pathway of the obligate intracellular bacteriumChlamydiafrom cells is unknown. Using a GFP-based approach to visualize chlamydial inclusions within cells by live fluorescence videomicroscopy, we identified thatChlamydiarelease occurred by two mutually exclusive pathways. The first, lysis, consisted of an ordered sequence of membrane permeabilizations: inclusion, nucleus and plasma membrane rupture. Treatment with protease inhibitors abolished inclusion lysis. Intracellular calcium signaling was shown to be important for plasma membrane breakdown. The second release pathway was a packaged release mechanism, called extrusion. This slow process resulted in a pinching of the inclusion, protrusion out of the cell within a cell membrane compartment, and ultimately detachment from the cell. Treatment ofChlamydia-infected cells with specific pharmacological inhibitors of cellular factors demonstrated that extrusion required actin polymerization, neuronal Wiskott–Aldrich syndrome protein, myosin II and Rho GTPase. The participation of Rho was unique in that it functioned late in extrusion. The dual nature of release characterized forChlamydiahas not been observed as a strategy for intracellular bacteria.
Chymotrypsin C (caldecrin) promotes degradation of human cationic trypsin: Identity with Rinderknecht's enzyme Y
Authors: Szmola Richárd , Sahin-Tóth Miklós
Published: June 2007

Digestive trypsins undergo proteolytic breakdown during their transit in the human alimentary tract, which has been assumed to occur through trypsin-mediated cleavages, termed autolysis. Autolysis was also postulated to play a protective role against pancreatitis by eliminating prematurely activated intrapancreatic trypsin. However, autolysis of human cationic trypsin is very slow
in vitro
, which is inconsistent with the documented intestinal trypsin degradation or a putative protective role. Here we report that degradation of human cationic trypsin is triggered by chymotrypsin C, which selectively cleaves the Leu
81
-Glu
82
peptide bond within the Ca
2+
binding loop. Further degradation and inactivation of cationic trypsin is then achieved through tryptic cleavage of the Arg
122
-Val
123
peptide bond. Consequently, mutation of either Leu
81
or Arg
122
blocks chymotrypsin C-mediated trypsin degradation. Calcium affords protection against chymotrypsin C-mediated cleavage, with complete stabilization observed at 1 mM concentration. Chymotrypsin C is highly specific in promoting trypsin degradation, because chymotrypsin B1, chymotrypsin B2, elastase 2A, elastase 3A, or elastase 3B are ineffective. Chymotrypsin C also rapidly degrades all three human trypsinogen isoforms and appears identical to enzyme Y, the enigmatic trypsinogen-degrading activity described by Heinrich Rinderknecht in 1988. Taken together with previous observations, the results identify chymotrypsin C as a key regulator of activation and degradation of cationic trypsin. Thus, in the high Ca
2+
environment of the duodenum, chymotrypsin C facilitates trypsinogen activation, whereas in the lower intestines, chymotrypsin C promotes trypsin degradation as a function of decreasing luminal Ca
2+
concentrations.
Diversity enhances agricultural productivity via rhizosphere phosphorus facilitation on phosphorus-deficient soils
Authors: Li Long , Li Shu-Min , Sun Jian-Hao , Zhou Li-Li , Bao Xing-Guo , Zhang Hong-Gang , Zhang Fu-Suo
Published: June 2007

Intercropping, which grows at least two crop species on the same pieces of land at the same time, can increase grain yields greatly. Legume–grass intercrops are known to overyield because of legume nitrogen fixation. However, many agricultural soils are deficient in phosphorus. Here we show that a new mechanism of overyielding, in which phosphorus mobilized by one crop species increases the growth of a second crop species grown in alternate rows, led to large yield increases on phosphorus-deficient soils. In 4 years of field experiments, maize (
Zea mays
L.) overyielded by 43% and faba bean (
Vicia faba
L.) overyielded by 26% when intercropped on a low-phosphorus but high-nitrogen soil. We found that overyielding of maize was attributable to below-ground interactions between faba bean and maize in another field experiment. Intercropping with faba bean improved maize grain yield significantly and above-ground biomass marginally significantly, compared with maize grown with wheat, at lower rates of P fertilizer application (<75 kg of P
2
O
5
per hectare), and not significantly at high rate of P application (>112.5 kg of P
2
O
5
per hectare). By using permeable and impermeable root barriers, we found that maize overyielding resulted from its uptake of phosphorus mobilized by the acidification of the rhizosphere via faba bean root release of organic acids and protons. Faba bean overyielded because its growth season and rooting depth differed from maize. The large increase in yields from intercropping on low-phosphorus soils is likely to be especially important on heavily weathered soils.
Dual specificities of the glyoxysomal/peroxisomal processing protease Deg15 in higher plants
Authors: Helm Michael , Lück Carsten , Prestele Jakob , Hierl Georg , Huesgen Pitter F. , Fröhlich Thomas , Arnold Georg J. , Adamska Iwona , Görg Angelika , Lottspeich Friedrich , Gietl Christine
Published: June 2007

Glyoxysomes are a subclass of peroxisomes involved in lipid mobilization. Two distinct peroxisomal targeting signals (PTSs), the C-terminal PTS1 and the N-terminal PTS2, are defined. Processing of the PTS2 on protein import is conserved in higher eukaryotes. The cleavage site typically contains a Cys at P1 or P2. We purified the glyoxysomal processing protease (GPP) from the fat-storing cotyledons of watermelon (
Citrullus vulgaris
) by column chromatography, preparative native isoelectric focusing, and 2D PAGE. The GPP appears in two forms, a 72-kDa monomer and a 144-kDa dimer, which are in equilibrium with one another. The equilibrium is shifted on Ca
2+
removal toward the monomer and on Ca
2+
addition toward the dimer. The monomer is a general degrading protease and is activated by denatured proteins. The dimer constitutes the processing protease because the substrate specificity proven for the monomer (Φ-Arg/Lys↓) is different from the processing substrate specificity (Cys-Xxx↓/Xxx-Cys↓) found with the mixture of monomer and dimer. The
Arabidopsis
genome analysis disclosed three proteases predicted to be in peroxisomes, a Deg-protease, a pitrilysin-like metallopeptidase, and a Lon-protease. Specific antibodies against the peroxisomal Deg-protease from
Arabidopsis
(Deg15) identify the watermelon GPP as a Deg15. A knockout mutation in the
DE
G1
5
gene of
Arabidopsis
(At1g28320) prevents processing of the glyoxysomal malate dehydrogenase precursor to the mature form. Thus, the GPP/Deg15 belongs to a group of trypsin-like serine proteases with
Escherichia coli
DegP as a prototype. Nevertheless, the GPP/Deg15 possesses specific characteristics and is therefore a new subgroup within the Deg proteases.
Structure of pyrrolysyl-tRNA synthetase, an archaeal enzyme for genetic code innovation
Authors: Kavran Jennifer M. , Gundllapalli Sarath , O'Donoghue Patrick , Englert Markus , Söll Dieter , Steitz Thomas A.
Published: June 2007

Pyrrolysine (Pyl), the 22nd natural amino acid and genetically encoded by UAG, becomes attached to its cognate tRNA by pyrrolysyl-tRNA synthetase (PylRS). We have determined three crystal structures of the
Methanosarcina mazei
PylRS complexed with either AMP–PNP, Pyl–AMP plus pyrophosphate, or the Pyl analogue
N
-ε-[(cylopentyloxy)carbonyl]-
l
-lysine plus ATP. The structures reveal that PylRS utilizes a deep hydrophobic pocket for recognition of the Pyl side chain. A comparison of these structures with previously determined class II tRNA synthetase complexes illustrates that different substrate specificities derive from changes in a small number of residues that form the substrate side-chain-binding pocket. The knowledge of these structures allowed the placement of PylRS in the aminoacyl-tRNA synthetase (aaRS) tree as the last known synthetase that evolved for genetic code expansion, as well as the finding that Pyl arose before the last universal common ancestral state. The PylRS structure provides an excellent framework for designing new aaRSs with altered amino acid specificity.
BLM helicase–dependent and –independent roles of 53BP1 during replication stress–mediated homologous recombination
Authors: Tripathi Vivek , Nagarjuna Tirunelvely , Sengupta Sagar
Published: June 2007

Mutations in BLM helicase cause Bloom syndrome, characterized by predisposition to all forms of cancer. We demonstrate that BLM, signal transducer 53BP1, and RAD51 interact during stalled replication. Interactions between the three proteins have functional consequences. Lack of 53BP1 decreases the cell survival and enhanced chromosomal aberration after replication arrest. 53BP1 exhibits both BLM-dependent and -independent anti-recombinogenic functions in human and mouse cells. Both BLM and 53BP1 abrogate endogenous RAD51 foci formation and disrupt RAD51 polymerization. Consequently, loss of BLM and 53BP1 synergistically enhances stress-dependent homologous recombination. These results provide evidence regarding the cooperation between BLM and 53BP1 during maintenance of genomic integrity.
Regulation of secretory transport by protein kinase D–mediated phosphorylation of the ceramide transfer protein
Authors: Fugmann Tim , Hausser Angelika , Schöffler Patrik , Schmid Simone , Pfizenmaier Klaus , Olayioye Monilola A.
Published: June 2007

Protein kinase D (PKD) has been identified as a crucial regulator of secretory transport at the trans-Golgi network (TGN). Recruitment and activation of PKD at the TGN is mediated by the lipid diacylglycerol, a pool of which is generated by sphingomyelin synthase from ceramide and phosphatidylcholine. The nonvesicular transfer of ceramide from the endoplasmic reticulum to the Golgi complex is mediated by the lipid transfer protein CERT (ceramide transport). In this study, we identify CERT as a novel in vivo PKD substrate. Phosphorylation on serine 132 by PKD decreases the affinity of CERT toward its lipid target phosphatidylinositol 4-phosphate at Golgi membranes and reduces ceramide transfer activity, identifying PKD as a regulator of lipid homeostasis. We also show that CERT, in turn, is critical for PKD activation and PKD-dependent protein cargo transport to the plasma membrane. Thus, the interdependence of PKD and CERT is key to the maintenance of Golgi membrane integrity and secretory transport.