bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature dependent transient velocity and mobility studies in an organic field effect transistor
Authors: Dunn Lawrence , Dodabalapur Ananth
Published: June 2010

We have investigated the temperature-dependent behavior of a pentacene organic field effect transistor (OFET) by measuring dc current and voltage characteristics and the transient response of the OFET to a sharp voltage pulse applied at the source contact. Standard transistor equations were used to extract the dc field-effect mobility, μFE, and the turn on time of the OFET was used to extract a dynamic mobility, μdynamic. Temperature dependent measurements were used to extract both field-effect and dynamic activation energies, Ea,FE and Ea,dynamic, over a range of effective gate voltages in order to vary the charge carrier density in the channel. We found that at higher temperatures μdynamic>μFE, while at lower temperatures μdynamic<μFE. We attribute this varying relationship between dynamic and field effect mobilities to the fact that μFE is an average mobility of all the charge carriers in the channel, while μdynamic is a measure of the mobility of the fastest charge carriers in the channel. We also found Ea,dynamic to be greater than Ea,FE by approximately 7 meV at the same effective gate voltage. We attribute this to the fact that Ea,dynamic is extracted from transient measurements made during the process of channel formation, and therefore at lower charge carrier densities than the corresponding values of Ea,FE. We also note that Ea,dynamic is a measure of the activation energy of the most energetic charge carriers in the channel, while Ea,FE is a measure of the average activation energies of all charge carriers in the channel.
Photochemical reaction dynamics in SO2-acetylene complexes
Authors: Makarov Vladimir I. , Kochubei Sergei A. , Khmelinskii Igor
Published: June 2010

The dynamics of photoinduced reactions between electronically excited SO2 molecule (Ã A12←X̃ A11) and acetylene molecule (X̃ Σ1g+) in the SO2-acetylene van der Waals (vdW) complexes (clusters) was studied. The SO2 molecule was excited by frequency-doubled radiation of a tunable dye laser, and resonance enhancement multiphoton photoionization of the produced photofragments was induced by ArF (193 nm) laser radiation or by frequency-doubled radiation of a second tunable dye laser to observe the C2H radical. The HOSO radical was detected by its IR emission. We found that the main photodecomposition channel of the vdW complexes (clusters) involves the SO2∗+C2H2→HOSO+C2H reaction. Indeed, the analysis of the action spectra of the excitation laser radiation showed that the photofragments emerging in our experimental conditions (SO2, 5%; C2H2, 5%; and Xe; P0=2 atm) originate from the SO2⋯C2H2 vdW complex (cluster). We analyzed the structure of this vdW complex theoretically, obtaining Cs symmetry, with the acetylene molecule located above the OSO plane. The resonance-enhanced multiphoton photoionization action spectra of the C2H (Ã←X̃) photofragmentation and the IR emission spectra of the HOSO radical allowed the authors to probe the energy distribution between the photofragments formed. The reaction that involves transition of the acetylene H atom to the SO2 oxygen should be the primary step of the process considered, followed by nonstatistic dissociation of the vdW complex (cluster), with the C2H radical formed in its vibrationless state and excited both rotationally and translationally, and the HOSO radical excited vibrationally, rotationally and translationally. The proposed reaction mechanism was discussed, employing transition-state and Rice-Ramsperger-Kassel-Marcus (RRKM) approaches. The kinetics of photofragment formation was investigated, yielding characteristic radical build-up time of 0.64 μs.
Photofragment angular momentum distributions in the molecular frame. II. Single state dissociation, multiple state interference, and nonaxial recoil in photodissociation of polyatomic molecules
Authors: Rakitzis T. Peter , Alexander Andrew J.
Published: June 2010

We present an aqk(s) polarization-parameter model to describe product angular momentum polarization from the one-photon photodissociation of polyatomic molecules in the molecular frame. We make the approximation that the final photofragment recoil direction is unique and described by the molecular frame polar coordinates (α,φi), for which the axial recoil approximation is a special case (e.g., α=0). This approximation allows the separation of geometrical and dynamical factors, in particular, the expression of the experimental sensitivities to each of the aqk(s) in terms of the molecular frame polar angles (χi,φi) of the transition dipole moment μi. This separation is applied to the linearly polarized photodissociation of polyatomic molecules (asymmetric, symmetric, and spherical top molecules are discussed) and to all dissociation mechanisms that satisfy our recoil approximation, including those with nonaxial recoil and multiple state interference, giving important insight into the geometrical properties of the photodissociation mechanism. For example, we demonstrate that the ratio of polarization parameters A0k(aniso)/A0k(iso)=β (where β is the spatial anisotropy parameter) is an indication that the dynamics can be explained by a single dissociative state. We also show that for asymmetric top photodissociation, the sensitivity to the a1k(s) parameters, which can arise either from single-surface or multiple-surface interference mechanisms, is nonzero only for components of the transition dipole moments within the v-d plane of the recoil frame.
Calculation of interfacial properties via free-energy-based molecular simulation: The influence of system size
Authors: Grzelak Eric M. , Errington Jeffrey R.
Published: June 2010

We examine several issues related to the calculation of interfacial properties via analysis of an interface potential obtained from grand canonical Monte Carlo simulation. Two model systems are examined. One includes a monatomic Lennard-Jones fluid that interacts with a structureless substrate via a long-ranged substrate potential. The second model contains a monatomic Lennard-Jones fluid that interacts with an atomistically detailed substrate via a short-ranged potential. Our results are presented within the context of locating the wetting point. Two methods are used to compute the wetting temperature. In both cases we examine the system size dependence of the key property used to deduce the wetting temperature as well as the robustness of the scaling relationship employed to describe the evolution of this property with temperature near the wetting point. In the first approach we identify the wetting transition as the point at which the prewetting and bulk saturation curves meet. In this case, the prewetting saturation chemical potential is the key quantity of interest. In the second approach we find the point at which the spreading coefficient evaluates to zero. We find that the effect of system size is adequately described by simple scaling functions. Moreover, estimates of the wetting temperature for finite-sized systems characterized by a linear dimension greater than 12 fluid diameters differ by less than 1% from an otherwise equivalent macroscopic system. Modification of the details regarding the use of simulation data to compute the wetting temperature can also produce a shift in this quantity of up to 1%. As part of this study, we also examine techniques for describing the shape of the interface potential at a relatively high surface density. This analysis is particularly relevant for systems with long-ranged substrate potentials for which the interface potential approaches a limiting value asymptotically.
An analysis of superhydrophobic turbulent drag reduction mechanisms using direct numerical simulation
Authors: Martell Michael B. , Rothstein Jonathan P. , Perot J. Blair
Published: June 2010

Superhydrophobic surfaces combine hydrophobic surface chemistry with topological microfeatures. These surfaces have been shown to provide drag reduction in laminar and turbulent flows. In this work, direct numerical simulation is used to investigate the drag reducing performance of superhydrophobic surfaces in turbulent channel flow. Slip velocities, wall shear stresses, and Reynolds stresses are determined for a variety of superhydrophobic surface microfeature geometry configurations at friction Reynolds numbers of Reτ≈180, Reτ≈395, and Reτ≈590. This work provides evidence that superhydrophobic surfaces are capable of reducing drag in turbulent flow situations by manipulating the laminar sublayer. For the largest microfeature spacing, an average slip velocity over 80% of the bulk velocity is obtained, and the wall shear stress reduction is found to be greater than 50%. The simulation results suggest that the mean velocity profile near the superhydrophobic wall continues to scale with the wall shear stress and the log layer is still present, but both are offset by a slip velocity that is primarily dependent on the microfeature spacing.
Radius selection and droplet unpinning in vapor-liquid-solid-grown nanowires
Authors: Roper S. M. , Anderson A. M. , Davis S. H. , Voorhees P. W.
Published: June 2010

The requirements for steady nanowire growth under near-equilibrium conditions in the vapor-liquid-solid (VLS) method is examined with particular emphasis on the configuration of the liquid droplet. It is found that the final radius of a cylindrical wire is selected by the fixed volume of liquid VL and the surface-energy ratio γsl/γlv but is independent of the solid-vapor energy γsv. Existing models for growth, based on a balance of configurational forces at the triple junction, are shown to be consistent with the principle of maximal release of free energy. Gibbs’s results on allowable contact angles at a sharp corner predict conditions on γsl/γlv and γsv/γlv for the existence of straight-wire growth. For parameter values that violate these conditions the droplet atop the wire is expected to unpin. A range of alternative configurations for the liquid exist and their relative energies are compared. In particular, it is found that for a certain region in parameter space—not extraordinary in VLS growth—a spherical cap of liquid is not in equilibrium and an annulus of liquid surrounding the wire is energetically preferred. This is suggestive of a possible instability during growth.
The detection of electron-beam-induced current in junctionless semiconductor
Authors: Tan Chee Chin , Ong Vincent K. S.
Published: June 2010

The scanning electron microscope is a versatile tool and its electron beam techniques have been widely used in semiconductor material and device characterizations. One of these electron beam techniques is the electron-beam-induced current (EBIC) technique. One of the limitations of the conventional EBIC technique is that it requires charge collecting junctions which may not be readily available in junctionless samples such as bare substrates unless some special sample preparation procedure such as the fabrication of a diffused junction is done on the junctionless sample. In this paper, the technique of detecting EBIC current in junctionless samples with the use of a two-point probe is presented. It is found that the EBIC current is independent from its physical parameter when the sample thickness is greater than 4L; the width to the right of probe 2 and the width to the left of probe 1 are greater than 2L and 8L, respectively. The parameters affecting this technique of detecting the EBIC current such as the depth of the generation volume, probe spacing, and the applied bias are also discussed in this paper. A commercially available two-dimensional device simulator was used to verify this technique.
Tuning electronic structure of graphene via tailoring structure: Theoretical study
Authors: He H. Y. , Zhang Y. , Pan B. C.
Published: June 2010

Electronic structures of graphene sheet with different defective patterns are investigated, based on the first principles calculations. We find that defective patterns can tune the electronic structures of the graphene significantly. Triangle patterns give rise to strongly localized states near the Fermi level, and hexagonal patterns open up band gaps in the systems. In addition, rectangular patterns, which feature networks of graphene nanoribbons (GNRs) with either zigzag or armchair edges, exhibit semiconducting behaviors, where the band gap has an evident dependence on the width of the nanoribbons. For the networks of the GNRs, some special channels for electronic transport are predicted.
Complex permittivity measurements using cavity perturbation technique with substrate integrated waveguide cavities
Authors: Lobato-Morales Humberto , Corona-Chávez Alonso , Murthy D. V. B. , Olvera-Cervantes José L.
Published: June 2010

Cavity perturbation technique is widely used in the measurements of complex dielectric permittivity of materials due to its accuracy and ease of configuration. This paper presents the theoretical formulas for the evaluation of complex permittivity of materials using cavity perturbation technique with substrate integrated cavity resonators. With the proposed formulas, the use of various planar cavities is possible by taking into account the dielectric characteristics of the substrate in which the cavity is implemented. Simulations and measurements are performed on various dielectric samples to validate the proposed theory. The maximum deviation in the measured dielectric permittivity values is below 6% compared to the literature values. The implemented substrate integrated cavity is then analyzed in terms of sensitivity, showing a good performance.
The effect of the Hall term on Jeans instability in quantum magnetoplasma with resistive effects
Authors: Wu Zhengwei , Ren Haijun , Cao Jintao , Chu Paul K.
Published: June 2010

The Jeans instability in dense quantum plasmas is investigated by taking into account the Hall term and resistivity in the presence of two-dimensional magnetic fields. The general dispersion relation is presented. The presence of the Hall term introduces a new wave mode which does not exist in the ideal magnetohydrodynamic framework. Two limiting cases with respect to the Hall effect are discussed. The Hall effect is shown to induce a frequency shift but does not change the instability criterion. The resistivity exhibits damping or destabilizing effects on the plasma system under different circumstances. The analytical expressions of the growth/damping rate of Jeans instability are obtained for both the finite and remarkable resistivity cases in the absence of the Hall term.
Nanoparticle interaction potentials constructed by multiscale computation
Authors: Lee Cheng K. , Hua Chi C.
Published: June 2010

The van der Waals (vdW) potentials governing macroscopic objects have long been formulated in the context of classical theories, such as Hamaker’s microscopic theory and Lifshitz’s continuum theory. This work addresses the possibility of constructing the vdW interaction potentials of nanoparticle species using multiscale simulation schemes. Amorphous silica nanoparticles were considered as a benchmark example for which a series of (SiO2)n (n being an integer) has been systematically surveyed as the potential candidates of the packing units that reproduce known bulk material properties in atomistic molecular dynamics simulations. This strategy led to the identification of spherical Si6O12 molecules, later utilized as the elementary coarse-grained (CG) particles to compute the pair interaction potentials of silica nanoparticles ranging from 0.62 to 100 nm in diameter. The model nanoparticles so built may, in turn, serve as the children CG particles to construct nanoparticles assuming arbitrary sizes and shapes. Major observations are as follows. The pair interaction potentials for all the investigated spherical silica nanoparticles can be cast into a semiempirical, generalized Lennard-Jones 2α−α potential (α being a size-dependent, large integral number). In its reduced form, we discuss the implied universalities for the vdW potentials governing a certain range of amorphous nanoparticle species as well as how thermodynamic transferability can be fulfilled automatically. In view of future applications with colloidal suspensions, we briefly evaluated the vdW potential in the presence of a “screening” medium mimicking the effects of electrical double layers or grafting materials atop the nanoparticle core. The general observations shed new light on strategies to attain a microscopic control over interparticle attractions. In future perspectives, the proposed multiscale computation scheme shall help bridge the current gap between the modeling of polymer chains and macroscopic objects by introducing molecular models coarse-grained at a similar level so that the interactions between these two can be treated in a consistent and faithful way.
Desktop megawatt superradiant free-electron laser at terahertz frequencies
Authors: Huang Yen-Chieh
Published: June 2010

I present a theoretical and simulation study of a desktop, megawatt (MW), terahertz (THz) superradiance free-electron laser (FEL) driven by a THz-pulse-train photoinjector. With nominal electron parameters from a THz-pulse-train photoinjector, this superradiant FEL is capable of generating more than 5 MW power at THz frequencies from a half-meter, single-pass undulator. Tapering the undulator to a length of 1.5 m can further increase the FEL output power to nearly 15 MW.
Controlled electronic transport in single-walled carbon nanotube networks: Selecting electron hopping and chemical doping mechanisms
Authors: Han Z. J. , Ostrikov K.
Published: June 2010

The electronic transport in both intrinsic and acid-treated single-walled carbon nanotube networks containing more than 90% semiconducting nanotubes is investigated using temperature-dependent resistance measurements. The semiconducting behavior observed in the intrinsic network is attributed to the three-dimensional electron hopping mechanism. In contrast, the chemical doping mechanism in the acid-treated network is found to be responsible for the revealed metal-like linear resistivity dependence in a broad temperature range. This effective method to control the electrical conductivity of single-walled carbon nanotube networks is promising for future nanoscale electronics, thermometry, and bolometry.
II–VI semiconductor color converters for efficient green, yellow, and red light emitting diodes
Authors: Haase M. A. , Xie J. , Ballen T. A. , Zhang J. , Hao B. , Yang Z. H. , Miller T. J. , Sun X. , Smith T. L. , Leatherdale C. A.
Published: June 2010

II–VI compound semiconductor quantum-well heterostructures were fabricated for use as efficient, narrow-spectrum, photoluminescent color converters to generate green, yellow, or red light when photopumped with blue GaInN light emitting diodes (LEDs). This approach promises high efficiencies in a wide range of wavelengths that includes the green-yellow portion of the spectrum where conventional LEDs offer relatively low efficiency. External quantum conversion efficiencies of 60%–70% and output spectra with full width at half maximum of 15 nm were achieved using CdZnSe–CdMgZnSe quantum wells grown by molecular beam epitaxy on InP substrates.
Effect of humidity on hydrogen sensitivity of Pt-gated AlGaN/GaN high electron mobility transistor based sensors
Authors: Lo C. F. , Chang C. Y. , Chu B. H. , Pearton S. J. , Dabiran A. , Chow P. P. , Ren F.
Published: June 2010

The effects of relative humidity on sensing characteristics of Pt-gated AlGaN/GaN high electron mobility transistor diode based hydrogen sensors were investigated. The absorbed water and oxygen molecules blocked available Pt surface adsorption sites for H2 absorption and reduced the hydrogen sensing sensitivity compared to low humidity conditions. The hydrogen sensing sensitivity decreased proportional to the relative humidity. However, the presence of humidity improved the sensor recovery characteristics after exposure to the hydrogen ambient.
Effect of birthweight and birth rank on the survival of single and twin lambs born to ewe lambs
Authors: Schreurs N. M. , Kenyon P. R. , Mulvaney F. J. , Morel P. C. H. , West D. M. , Morris S. T.
Published: June 2010

Benefits of ewe lamb mating include improved lifetime production, increased rates of genetic gain and higher net profits. These benefits are only achieved if the ewe lamb successfully rears its offspring to weaning. A meta-analytic approach was used to assess the effects of birthweight and the interacting effect of birth rank on the survival to weaning of lambs born to ewe lambs. The data were from eight studies where birthweight and weight at weaning had been recorded for lambs born from ewe lambs. Data were for single- (n = 1392) or twin-born lambs (n = 456). The twin lambs were further classified as the ‘heavier’ or ‘lighter’ of the pair to give three birth rank categories. To compare the probability of dying before weaning between birth ranks, but with lambs compared at a similar birthweight, lambs were categorised by their birthweight as heavy (>3.8 kg) or light (<3.8 kg) and also categorised within their birth rank on their placement around the mean birthweight (birthweight deviation). A mid-range birthweight deviation fell between one standard deviation above or below the mean for each birth rank, whereas a low- and high-range birthweight fell below and above the mid-range, respectively. Logistic regression was used to assess the effect of birth rank (single, heavier twin and lighter twin) and birthweight on lamb mortality up to weaning. To compare the probability of surviving up to weaning between the different birth ranks, relative risk ratios were calculated. Birth ranks were compared for lambs within the same birthweight group (heavy or light) and same birthweight deviation (low-, mid-, high-range). Decreasing birthweight increased mortality before weaning in twins and the change in mortality was greater for the lighter twin. Birthweight did not alter mortality before weaning in singles. Comparison of the birth ranks showed that there were differences (P < 0.05) in the probability of dying for lambs of different birth ranks but similar birthweight. The results suggest that management options for ewe lambs that increase the birthweight of the lighter twin could increase the weaning percentage.
Response of additional ewe lamb liveweight during gestation on birth and weaning weight of offspring and liveweight of the ewe lamb at weaning
Authors: Schreurs N. M. , Kenyon P. R. , Mulvaney F. J. , Morel P. C. H. , West D. M. , Morris S. T.
Published: June 2010

Increasing the liveweight of ewe lambs during gestation may have positive effects on lamb birthweight and weaning weight and also on ewe lamb liveweight at weaning. Specific times during the gestation period of the ewe lamb may be more responsive to improved nutrition and increases in liveweight. The objective of this work was to use a meta-analytic approach to investigate the effects of ewe lamb liveweight at mating and during pregnancy on lamb birth and weaning weights, and the ewe lamb’s liveweight at weaning. Increasing ewe lamb liveweight in early gestation and in particular before mating gave the greatest increases in the birth and weaning weight of the lambs, and also of the ewe lamb’s liveweight at weaning compared with increasing liveweight in the second and third trimester of gestation. This indicates that management practices for ewe lambs that generate higher liveweight at mating are likely to result in increased lamb survival, higher weaning percentages, greater lamb weaning weights and create rising 2-year-old ewes with better liveweight for mating in the subsequent season. Compared with ewe lambs that gave birth and reared singletons to weaning, those ewe lambs that gave birth to twins and reared twins had greater increases in lamb birthweights, lamb weaning weights and ewe lamb weights at weaning for each extra kilogram of ewe lamb liveweight during gestation. For ewe lambs, especially those that birth and rear twins, management options that increase the pre-mating weights will have the greatest response in lamb birthweight, weaning weight and liveweight of the ewe lamb itself at weaning.
Investigating Eremophila glabra as a bioactive agent for preventing lactic acidosis in sheep
Authors: Hutton P. G. , Durmic Z. , Vercoe P. E.
Published: June 2010

The Australian native plant Eremophila glabra was tested as a potential agent for preventing lactic acidosis in sheep after it was observed to be effective against acidosis in vitro. Ruminally fistulated wethers were infused via rumen cannula with single doses of kibbled wheat (14 g/kg bodyweight) and either virginiamycin (Eskalin500; AB, 80 mg/kg of wheat plus 100 g milled oaten hay/kg of wheat, n = 6), E. glabra (EG, 100 g freeze-dried and milled leaf material per kg of wheat, n = 10) or milled oaten hay (Control, 100 g milled oaten hay/kg of wheat, n = 16). Rumen samples were collected immediately before infusion and then 2, 4, 6, 8, 12, 16 and 24 h after the infusion. The samples were analysed for pH, D-lactate, volatile fatty acids (VFA) and osmolality. Rumen pH and D-lactate values indicative of acidosis were detected in the Control and EG groups. The pH nadir of the rumen was 12 h after the wheat infusion, at which time the values in the EG (pH = 4.87) and Control (pH = 5.09) groups were lower (P < 0.05) than in the AB group (pH = 5.63) and the D-lactate concentrations were higher (P < 0.05) in the EG and Control groups (24 mmol/L and 15 mmol/L, respectively) than in the AB group (0.9 mmol/L). At the same time, total VFA concentration was higher (P < 0.05) in the AB group (102 mmol/L) than in the Control (65 mmol/L) and the EG (14 mmol/L) groups. Rumen osmolality did not differ between groups. Virginiamycin was effective at preventing lactic acidosis. However, the inclusion of dried leaves from E. glabra at a similar level that was effective in vitro did not prevent lactic acidosis in vivo, and the reasons behind this remain unclear. The study demonstrates the difficulty in converting in vitro results to in vivo and highlights the need to test the plant at higher doses in vivo.
Breech bareness reduces flystrike in New Zealand crossbred sheep
Authors: Scobie D. R. , O'Connell D.
Published: June 2010

Two experiments on the effect of breech bareness on flystrike are reported here. Sires from commercial sources (n = 2) and from a mixed breed flock selected for breech bareness (n = 5) were mated to ewes from the same flock and Romney ewes. Lambs (n = 211) were run as one mob from docking to weaning. Within 2 days before weaning, flystrike affected several lambs. At weaning the lambs were inspected for breech bareness score and dag score. Flystruck lambs were recorded, treated and removed at weaning. The remaining lambs (n = 185) were regularly inspected and treated for flystrike, and the incidence of flystrike was recorded again 1 month later. There were no significant differences between sire groups, but the progeny of Romney dams were more likely to be flystruck (18.7 vs 3.4% and 24 vs 3.7%) on both occasions (P < 0.05). Flystrike increased with increasing dag score (P < 0.001) but dag score decreased with increasing breech bareness (P < 0.001). The ewe progeny (n = 800) of 17 Romney sires were run as one flock following weaning on a commercial farm in the North Island of New Zealand. The lambs were inspected for breech bareness, dag score and the incidence of flystrike following a brief period of fly challenge. As breech bareness score increased, dag score declined (P < 0.001) with a significant effect of sire on dag score (P < 0.001). Breech bareness had a significant influence on the proportion of lambs with flystrike (P = 0.028), most likely through dag score which explained a greater proportion of variation in flystrike in multiple linear regression (P < 0.001). Selection against dags in New Zealand crossbred sheep could lower flystrike risk, but selection for increasing breech bareness will reduce both dagginess and flystrike risk.
Effects of sowing rate and grazing management of forage rape (Brassica napus) on grazing behaviour and utilisation by dairy cattle
Authors: Stefanski E. P. , Garcia S. C. , Farina S. R. , Tan D. K. Y. , Tanner D.
Published: June 2010

The increase in total factor productivity in the Australian dairy industry over the last 10 years has been low (1.5%). To help address this issue, ‘FutureDairy’ is aiming to increase the production of home-grown feed currently achieved from pastures using a complementary forage-rotation (CFR) system. Forage rape (Brassica napus) is a key component of the CFR; however, it is a complex crop to manage and feed, and the interactions between the behaviour and grazing habits of dairy cattle are unknown. The present experiment investigated the effect of the sowing rate and grazing management of forage rape on the grazing behaviour and forage utilisation of lactating dairy cattle. A field experiment was established, with a forage rape crop planted at three different sowing rates of 2, 3.5 and 5 kg/ha. The crop was grazed using either a ‘multiple grazing’ system, where the forage rape was strip-grazed in a manner to promote regrowth to allow for regrazing, or a ‘take-all grazing’ system, where the forage rape was grazed once only after reaching maximum biomass. The grazing preferences of cows for the sowing rates during the grazing sessions were visually observed and recorded, and forage utilisation was determined from pre-grazing and post-grazing forage availability. Nitrogen (N) deposition from excreta was estimated using stocking density and time spent. Cattle preferred grazing the forage rape sown at 2 kg/ha, but this preference did not result in higher forage utilisation. Grazing method had no effect on forage utilisation or N deposition. Cows should be removed after ~80 min of grazing in a multiple grazing system to ensure future regrowth. Further work is necessary to fully investigate the effects of grazing method on forage utilisation and N deposition, and more accurate external devices and internal markers should be used in the future to provide better estimates of forage utilisation.
Dust emissions from a tunnel-ventilated broiler poultry shed with fresh and partially reused litter
Authors: Modini Robin L. , Agranovski Victoria , Meyer N. K. , Gallagher Erin , Dunlop Mark , Ristovski Zoran D.
Published: June 2010

Dust emissions from large-scale, tunnel-ventilated poultry sheds could have negative health and environmental impacts. Despite this fact, the literature concerning dust emissions from tunnel-ventilated poultry sheds in Australia and overseas is relatively scarce. Dust measurements were conducted during two consecutive production cycles at a single broiler shed on a poultry farm near Ipswich, Queensland. Fresh litter was employed during the first cycle and partially reused litter was employed during the second cycle. This provided an opportunity to study the effect that partial litter reuse has on dust emissions. Dust levels were characterised by the number concentration of suspended particles having a diameter between 0.5 and 20 μm and by the mass concentration of dust particles of less than 10 μm diameter (PM10) and 2.5 μm diameter (PM2.5). In addition, we measured the number size distributions of dust particles. The average concentration and emission rate of dust was higher when partially reused litter was used in the shed than when fresh litter was used. In addition, we found that dust particles emitted from the shed with partially reused litter were finer than the particles emitted with fresh litter. Although the change in litter properties is certainly contributing to this observed variability, other factors such as ventilation rate and litter moisture content are also likely to be involved.
Fibre production by beef cows
Authors: McGregor B. A. , Graham J. F.
Published: June 2010

Cattle grow and shed fibre which assists them adapt to seasonal changes in the environment. In the absence of cattle fibre production data for southern Australia, Angus, Hereford, Simmental and Limousin cows and crosses between these breeds grazing perennial pastures at Hamilton, Victoria were sampled in late winter. The fibre-growing area on the sides of cattle was measured, fibre sampled at the mid-side site and the sampling area determined. Fibre was tested for fibre diameter distribution, clean washing yield and fibre length measured. Cows were 3–7 years of age, liveweights were 412–712 kg and the mean fibre-growing area was 2.2 m2. This produced an average 682 g of total fibre (range 346–1175 g). The mean fibre diameter of all fibres was 51.7 µm (range 43–62 µm) and 18% of fibres were <36 µm (range 6–39%). The clean washing yield was 92.4% (range 87.4–95.8%). Fibre length averaged 21 mm. Increasing the age, liveweight and condition score of cows and increasing weight of clean fibre were associated with significant increases in mean fibre diameter. Breed of cattle did not affect fibre production (P > 0.1) but did affect mean fibre diameter (P < 0.05). The quantity of fibre production indicates potential for low value textile production. The high level of total fibre production, twice that of an earlier report, and fibre shedding from cattle suggests that white fibre-producing animals such as Merino sheep, Angora and cashmere goats and alpaca should avoid using cattle-handling facilities, particularly in the month before shearing.
Relationship of weaning weight to the mature liveweight of cashmere does on Australian farms
Authors: McGregor B. A. , Butler K. L.
Published: June 2010

Median weaning weight and its relationship with the median mature liveweight of does was quantified for four commercial Australian cashmere farms in various parts of Australia. Individual liveweights, of does of all ages at the time of weaning in December, ranged from 9 to 61 kg. Individual farm means of adult does (>1 year old) ranged from 24.6 to 38.8 kg. The model for the logarithm of liveweight was: log10(liveweight) = a + br(Age + 0.6); where a, b and r are parameters that are different for each farm. The result that the r parameter differs with farm was statistically significant (P = 9.4 × 10−6). The percentage variance accounted for was 84.4% and the residual standard deviation was 0.042. Farms differed greatly in the median mature liveweight with some farms reaching ~44 kg and others only 31 kg. Median weaning weight was 14.1 kg (range 11.4–16.8 kg). Median weaning weight as a percentage of median mature doe liveweight on a particular farm varied from 32 to 42%. These weaning weights appear low in absolute and relative terms and thus are likely to incur production penalties.
Management of young goats during prolonged fasting affects carcass characteristics but not pre-slaughter liveweight or cortisol
Authors: Greenwood P. L. , Finn J. A. , May T. J. , Nicholls P. J.
Published: June 2010

Effects of pre-slaughter management (72 h continual fasting; 24 h feeding within 72 h fasting; 24 h feeding plus 6 h additional transport within 72 h fasting) and of water availability, gender, weaning 3 weeks before slaughter, initial liveweight (LW) and body condition score (CS) on LW, plasma cortisol and carcass characteristics were studied in young goats. The goats (n = 229) were ~16 weeks of age, with a mean ± s.d. LW of 13.7 ± 2.4 kg. Pre-slaughter treatment did not significantly affect LW or carcass weight at slaughter, but goats fed within the fasting period had lighter-coloured meat compared with the continually fasted goats and the goats fed and transported during the fasting period. Interactions between fasting treatment and gender were evident for hot carcass weight (HCW), retail yield (kg) and dress (% pre-fasting LW). Fasting treatment also interacted with water availability for HCW and with weaning status for GR (12th rib, 110 mm from mid-line) tissue depth. Interactions were evident between gender and water availability for LW at slaughter, and between gender and weaning status for retail yield (% HCW). Weaning status interacted with pre-fasting LW to influence LW at slaughter, and fasting treatment interacted with pre-fasting body CS to influence dress (% pre-slaughter LW). The effects of gender, weaning status, water availability, initial LW and CS on the pre-slaughter LW and carcass characteristics were generally consistent with our previous findings on time off feed. The results show benefits of providing high-quality feed and water and of minimising transport of goat kids during prolonged pre-slaughter fasting. They provide additional information for estimation of carcass characteristics of young goats to be marketed for meat and to aid in the further development of welfare standards for goats. Further research on interactions between gender and pre-slaughter management factors that influence goat carcass characteristics and meat quality is warranted.
Synthesis and Preliminary Pharmacological Evaluation of Aryl Dithiolethiones with Cyclooxygenase-2-Selective Inhibitory Activity and Hydrogen Sulfide-Releasing Properties
Authors: Zanatta Shannon D. , Jarrott Bevyn , Williams Spencer J.
Published: June 2010

A series of 5-aryl-1,2-dithiolethiones and 5-aryl-1,2-dithiole-3-ones were investigated as hydrogen sulfide-releasing anti-inflammatory drugs. Generally, phenolic acetophenones were best protected by methoxymethyl groups and the dithiolethione group installed by treatment with carbon disulfide, hexamethyldisilathiane, and hexachloroethane. However, ether-protected acetophenones could be elaborated to β-keto esters and converted to dithiolethiones by treatment with phosphorus pentasulfide and elemental sulfur. Dethionation of dithiolethiones to 1,2-dithiole-3-ones was accomplished by mercury(ii)-promoted hydrolysis. A preliminary investigation of the dithiolethiones and dithiole-3-ones as inhibitors of cyclooxygenases COX-1 and COX-2 is discussed. Dithiolethiones bearing a 5-(2,6-di-tert-butyl-4-hydroxyphenyl) or 5-(2,6-di-tert-butyl-4-methoxyphenyl) substituent were the most effective inhibitors of COX-2 and displayed excellent selectivity against COX-1, comparable with rofecoxib, a representative coxib. It is shown that uncatalyzed hydrolysis of the thiocarbonyl group to release hydrogen sulfide leads to the corresponding carbonyl compound, and these carbonyl compounds are moderate COX-2 selective inhibitors.
Polyketide-peroxides from a Species of Jamaican Plakortis (Porifera: Demospongiae)
Authors: Mohammed Rabab , Peng Jiangnan , Kelly Michelle , Yousaf Muhammad , Winn Eustace , Odde Srinivas , Bie Zhi , Xie Aihua , Doerksen Robert J. , Hamann Mark T.
Published: June 2010

A new cyclic peroxide plakortisinic acid (1), and a new ketone derivative (2), in addition to six known compounds, an α,β-unsaturated ester (3), plakortide N (4), plakortide F (5) and its free acid (6), plakortone D (7), and a furan-containing molecule (8), were isolated from a species of Plakortis from Jamaica. The structures were elucidated by interpretation of 1D and 2D NMR spectra, and mass spectrometry data and by comparison with data from the literature. Comparison between experimental and calculated optical rotations allowed the assignment of absolute configuration of 1 and 2. The isolated compounds have been evaluated for their antimicrobial, antimalarial, anticancer, anti-Mtb, and anti HIV-1 activity.
Production of Omega-3 Triacylglycerol Concentrates using a New Food Grade Immobilized Candida antarctica Lipase B
Authors: Kralovec Jaroslav A. , Wang Weijie , Barrow Colin J.
Published: June 2010

Triacylglycerol concentrates of eicosapentaenoic and docosahexaenoic omega-3 fatty acids were synthesized either via transesterification or esterification of glycerol with the corresponding ethyl ester or free fatty acid concentrates, respectively. A newly developed food grade immobilized Candida antarctica lipase B system using an Amberlite FPX-66 hydrophobic matrix, was compared with a commercially available non-food grade commercial system, for their ability to catalyze these reactions. For either system, the transesterification required higher temperature (90°C) than esterification (70°C) to achieve maximum triacylglycerol yields. The newly developed immobilized system efficiently catalyzes the esterification of free fatty acids with glycerol and differs from the existing commercial system in that it is food grade and has a more uniform and larger particle distribution. The new system significantly improves flow in a packed bed reactor, enabling multiple reuse of the catalyst for up to 80 repeats.
Loss of human Greatwall results in G2 arrest and multiple mitotic defects due to deregulation of the cyclin B-Cdc2/PP2A balance
Authors: Burgess Andrew , Vigneron Suzanne , Brioudes Estelle , Labbé Jean-Claude , Lorca Thierry , Castro Anna
Published: June 2010

Here we show that the functional human ortholog of Greatwall protein kinase (Gwl) is the microtubule-associated serine/threonine kinase-like protein, MAST-L. This kinase promotes mitotic entry and maintenance in human cells by inhibiting protein phosphatase 2A (PP2A), a phosphatase that dephosphorylates cyclin B-Cdc2 substrates. The complete depletion of Gwl by siRNA arrests human cells in G2. When the levels of this kinase are only partially depleted, however, cells enter into mitosis with multiple defects and fail to inactivate the spindle assembly checkpoint (SAC). The ability of cells to remain arrested in mitosis by the SAC appears to be directly proportional to the amount of Gwl remaining. Thus, when Gwl is only slightly reduced, cells arrest at prometaphase. More complete depletion correlates with the premature dephosphorylation of cyclin B-Cdc2 substrates, inactivation of the SAC, and subsequent exit from mitosis with severe cytokinesis defects. These phenotypes appear to be mediated by PP2A, as they could be rescued by either a double Gwl/PP2A knockdown or by the inhibition of this phos-phatase with okadaic acid. These results suggest that the balance between cyclin B-Cdc2 and PP2A must be tightly regulated for correct mitotic entry and exit and that Gwl is crucial for mediating this regulation in somatic human cells.
Personality and reproductive success in a high-fertility human population
Authors: Alvergne Alexandra , Jokela Markus , Lummaa Virpi
Published: June 2010

The existence of interindividual differences in personality traits poses a challenge to evolutionary thinking. Although research on the ultimate consequences of personality differences in nonhuman animals has recently undergone a surge of interest, our understanding of whether and how personality influences reproductive decisions in humans has remained limited and informed primarily by modern societies with low mortality–fertility schedules. Taking an evolutionary approach, we use data from a contemporary polygynous high-fertility human population living in rural Senegal to investigate whether personality dimensions are associated with key life-history traits in humans, i.e., quantity and quality of offspring. We show that personality dimensions predict reproductive success differently in men and women in such societies and, in women, are associated with a trade-off between offspring quantity and quality. In women, neuroticism positively predicts the number of children, both between and within polygynous families. Furthermore, within the low social class, offspring quality (i.e., child nutritional status) decreases with a woman's neuroticism, indicating a reproductive trade-off between offspring quantity and quality. Consistent with this, maximal fitness is achieved by women at an intermediate neuroticism level. In men, extraversion was found to be a strong predictor of high social class and polygyny, with extraverted men producing more offspring than their introverted counterparts. These results have implications for the consideration of alternative adaptive hypotheses in the current debate on the maintenance of personality differences and the role of individual factors in fertility patterns in contemporary humans.
Monitoring of spatial water quality in lakes by remote sensing and transect measurements
Authors: Lepistö Ahti , Huttula Timo , Koponen Sampsa , Kallio Kari , Lindfors Antti , Tarvainen Marjo , Sarvala Jouko
Published: June 2010

New tools, such as intensive measurements, together with advanced mathematical models, are increasingly needed in water management and environmental research. The new approaches are being developed at Pyhäjärvi, a large (155 km2) lake in southwest Finland. Pyhäjärvi is highly valuable in terms of water supply, fisheries and recreational use. The ecological state of Pyhäjärvi has been closely monitored for decades, particularly since eutrophication became a major concern in the late 1980s. Two relatively new research methods were used to assess the spatial water quality of Pyhäjärvi: (i) transect measurements from a moving boat; and (ii) remote sensing data based estimates. First, a flow-through method from a moving boat was successfully used to collect high resolution transect water quality data from the lake over six field campaigns. The method is relatively accurate but costly, and its use is mostly limited to special campaigns and intensive research, but not for long-term monitoring. Second, remote sensing methods were used to retrieve water quality information which was found consistent with the surface measurements from the boat. The estimation of parameters such as turbidity and humic substance concentration is possible with simple algorithms when using remote sensing (MERIS) data. The quantitative estimation of water quality by the methods used here requires concurrent in situ measurements for algorithm training. These methods will be further developed utilizing frequent on-line water quality and weather data from a recently installed lake float.
Using geological history of the Laurentian Great Lakes to better understand their future
Authors: Lewis C. F. M. , Rea D. K. , Hubeny J. B. , Thompson T. A. , Blasco S. M. , King J. W. , Reddin M. , Moore T. C.
Published: June 2010

With growing use of numerical models to forecast lake conditions under future climates and other stressors, paleo-events in the history of the Great Lakes have greater potential for relevance. Past events and history may extend records of observations, provide estimates of the sensitivity of the lake system to stressing conditions, and contribute scenarios for model validation. Here we describe four examples that hold promise for improving understanding of the present and future Great Lakes: 1) using an event of lake closure to derive climate-hydrology sensitivity, 2) extending the record of lake-level history by examining beach ridge sequences, 3) investigating sedimentary black bands to indicate past anoxia at the lakebed in deep basins, and 4) deriving evidence of lake process teleconnections with atmospheric circulation.
The introduction of the endemic fish species,Lamprichthys Tanganicanus(Poeciliidae), from Lake Tanganyika into Lake Kivu: Possible causes and effects
Authors: Muderhwa Nshombo , Matabaro Lushombo
Published: June 2010

In the present study we compared morphological characteristics of the endemic fish species Lamprichthys tanganicanus (Poeciliidae) from Lake Tanganyika to those of similar fish samples which have appeared in Lake Kivu since 2006 to assess: (1) the taxonomic status of fish samples from Lake Kivu fisheries; (2) the food habits and fecundity of this fish and (3) the way by which this fish may have been introduced into this lake. Fish samples from Lake Kivu were collected in the bay of Bukavu and in Lake Tanganyika at Uvira. Metrics and meristics of Lamprichthys tanganicanus samples collected from Tanganyika were similar to those of fish collected in Lake Kivu indicating that recent fish samples caught together with Limnothrissa miodon in this lake indeed belong to Lamprichthys tanganicanus, a non-cichlid fish well known to be endemic to Lake Tanganyika. Genetic studies carried out on samples of this fish from both lakes support those conclusions. Moreover, mixed schools of Lamprichthys tanganicanus and Limnothrissa miodon fry were collected in the littoral zone of Lake Tanganyika suggesting that fry of the former species may have been accidentally introduced in Lake Kivu together with that of Limnothrissa miodon fifty years ago. Late appearance of this Tanganyikan non-cichlid species thirty years after Limnothissa miodon is discussed in relation to the biological characteristics of these two species.