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Ruminant feeding standards in Brazil are generally based on systems developed for temperate regions and there is a serious lack of information on grazed tropical pasture which is the main feedstuff. Signal grass (Brachiaria decumbens) represents half of the total cultivated pastures in Brazil (Miles et al., 1996). This study investigated the intake and digestibility by sheep of signal grass hay cut after re-growths of 28 and 56 days to represent the range used in practice in the Brazilian savanna. Lucerne hay was included as a positive control. The hays were offered at two levels of intake to Santa Ines wether sheep.
Maffei 2 is a highly obscured galaxy, probably of type Sbc, at a distance of 5 Mpc (Allen and Raimond 1972; Spinrad et al. 1973). Since it lies close to the Galactic plane, there is considerable confusion in infrared and 21-cm HI observations due to Galactic emission, but investigations of its structure can be carried out at millimeter wavelengths where the Galaxy contribution is confined to a limited velocity range. The high resolution (30″) of our CO J=2–1 observations permits both a detailed examination of Maffei 2 and a study of the nature of the gas in its nucleus, through comparison with the CO J=1–0 observations.
A recent outbreak of Q fever was linked to an intensive goat and sheep dairy farm in Victoria, Australia, 2012-2014. Seventeen employees and one family member were confirmed with Q fever over a 28-month period, including two culture-positive cases. The outbreak investigation and management involved a One Health approach with representation from human, animal, environmental and public health. Seroprevalence in non-pregnant milking goats was 15% [95% confidence interval (CI) 7–27]; active infection was confirmed by positive quantitative PCR on several animal specimens. Genotyping of Coxiella burnetii DNA obtained from goat and human specimens was identical by two typing methods. A number of farming practices probably contributed to the outbreak, with similar precipitating factors to the Netherlands outbreak, 2007-2012. Compared to workers in a high-efficiency particulate arrestance (HEPA) filtered factory, administrative staff in an unfiltered adjoining office and those regularly handling goats and kids had 5·49 (95% CI 1·29–23·4) and 5·65 (95% CI 1·09–29·3) times the risk of infection, respectively; suggesting factory workers were protected from windborne spread of organisms. Reduction in the incidence of human cases was achieved through an intensive human vaccination programme plus environmental and biosecurity interventions. Subsequent non-occupational acquisition of Q fever in the spouse of an employee, indicates that infection remains endemic in the goat herd, and remains a challenge to manage without source control.
Official suicide statistics for England are based on deaths given suicide verdicts and most cases given an open verdict following a coroner's inquest. Previous research indicates that some deaths given accidental verdicts are considered to be suicides by clinicians. Changes in coroners' use of different verdicts may bias suicide trend estimates. We investigated whether suicide trends may be over- or underestimated when they are based on deaths given suicide and open verdicts.
Possible suicides assessed by 12 English coroners in 1990/91, 1998 and 2005 and assigned open, accident/misadventure or narrative verdicts were rated by three experienced suicide researchers according to the likelihood that they were suicides. Details of all suicide verdicts given by these coroners were also recorded.
In 1990/91, 72.0% of researcher-defined suicides received a suicide verdict from the coroner, this decreased to 65.4% in 2005 (ptrend < 0.01); equivalent figures for combined suicide and open verdicts were 95.4% (1990/91) and 86.7% (2005). Researcher-defined suicides with a verdict of accident/misadventure doubled over that period, from 4.6% to 9.1% (p < 0.01). Narrative verdict cases rose from zero in 1990/91 to 25 in 2005 (4.2% of researcher-defined suicides that year). In 1998 and 2005, 50.0% of the medicine poisoning deaths given accidental/misadventure verdicts were rated as suicide by the researchers.
Between 1990/91 and 2005, the proportion of researcher-defined suicides given a suicide verdict by coroners decreased, largely due to an increased use of accident/misadventure verdicts, particularly for deaths involving poisoning. Consideration should be given to the inclusion of ‘accidental’ deaths by poisoning with medicines in the statistics available for monitoring suicides rates.
Nanocrystalline TiO2 compacts having initial approximate mean grain sizes of 14 nm and approximate green densities of 70% of theoretical were sintered by short-time exposure in a 2.45 GHz microwave cavity to maximum temperatures of 800, 1000 or 1200 ºC. Sample densities were measured before and after exposure to microwaves using Archimede's method. Transmission electron microscopy and x-ray diffraction were utilized to monitor grain growth and phase changes. Rutherford backscattering was used to monitor any changes in oxygen stoichiometry. The results of this study indicate that enhanced densification behavior is obtained for microwavesintered samples relative to samples sintered using conventional pressureless-sintering techniques.
The microwave heatability of various thermoplastic polymers was investigated. The concept of microwave calorimetry was proposed to quantitatively illustrate how viscoelastic behavior controlled microwave heatability. Specifically, heating rate as a function of sample temperature revealed a distinct maximum which was identified as the Tg at 2.45 GHz. The critical temperature, Tc, necessary for rapid microwave heating was identified by drawing a tangent to the heating rate curve and extrapolating to a critical value at zero heating rate. In separate experiments, low frequency (100 kHz) dielectric measurements were made which show the frequency dependence of Tg by means of Arrhenius activation energy plots. In general, the larger the activation energy, the closer the critical heating temperature, TC, was to the Tg determined by DSC. The smaller the activation energy, the further dielectric loss shifted with increased frequency so that Tc was very far from Tg determined by DSC.
Microwave processing has been utilized to process thermosetting polymeric materials. Specifically, fundamental studies relating epoxy network generation to processing conditions have been investigated in a tunable cylindrical cavity operating at a frequency of 2.45 GHz. These studies demonstrate that fully cured networks can be generated in ten minutes with the retention of good mechanical properties. Furthermore, toughened epoxy systems which utilize carefully designed amine terminated poly(arylene ether sulfone) thermoplastics as reactive oligomers have resulted in novel phase separated morphologies. In fact, it has been demonstrated that the morphology in these multiphase systems can actually be controlled by utilizing microwave processing. Bismaleimide toughened systems, devised by similar strategies, have demonstrated a 10–20 fold reduction in the time required to achieve full cure.
Multilayer ceramic capacitors of several compositions (both Z5U and NPO types) were sintered in air in both conventional and microwave furnaces. Several casketing and insulation techniques were used to improve temperature uniformity and minimize dopant losses. Zirconia and yttria are suitable packing materials as either powders or fibers. After sintering, the packing material remains friable and can be recycled. The presence of metallization layers did not interfere with the microwave process and no arcing was observed at surfaces where the internal electrodes emerged. In some runs, however, local thermal runaway was observed, which could severely decrease process yields and must be eliminated in a commercial process.
The structures of equal-thickness Co/Re multilayer films and several Co/Re bilayer films have been investigated by X-ray diffraction at low and high angles. Analysis of low-angle reflectivity data from bilayer films indicates that interfacial intermixing is limited to three monolayers and that the two interfacial configurations are different. The high-angle X-ray diffraction data show that multilayer films have coherent interfaces and a highly textured structure with hep  orientations normal to the film plane for periods 21 Å ≤ Λ ≤220 Å. Detailed structures have been determined by fitting the X-ray spectra to calculated ones using a trapezoidal model. The results indicate that samples with 42 Å≤ Λ ≤220 Å have relatively sharp interfaces, in good agreement with the bilayer results. In addition, an out-of-plane expansion of the Co (002) layer is observed in samples with large Λ and results from structural disorder leading to a reduced atomic density. For Λ <21 Å the interfaces arise from the rougher surfaces of the deposited layers.
Porous tantalum anodes were sintered at temperatures from 1600 to 1900°C using a conventional high-vacuum furnace as well as both 2.45 GHz fixed-frequency and 4-8 GHz variable-frequency microwave furnaces. Various insulation and casketing techniques were used to couple the microwave power to the tantalum compacts. Several types of tantalum powder were used to assess the effect of microwave processing on sintered surface area and impurity levels.
Some microwave sintered anodes have an unusual surface rippling not seen on conventionally fired parts. The rippling suggests that a microscopic arcing or plasma might have been generated. Two important effects could be exploited if this phenomenon can be controlled. First, the effective tantalum surface area could be increased, yielding higher capacitance per volume. Second, surface impurities might be cleaned away, allowing the formation of a better dielectric film during the anodization process and, ultimately, higher working voltage.
By using the techniques of normal Bragg scattering and glancing incidence scattering, we have measured both the out-of-plane and in-plane structures of GaixInxAs epilay-ers grown on GaAs (001) face by MOVPE. The data presented in this paper were collected from two samples: a thick epilayer of 40, 000A Ga0.84In0.16As, and a thin epilayer of 500Å Ga0.84In0.19As, which are lattice-mismatched with the substrate by about 1.14% and 1.36% respectively according to the Vegard's law. The measured average lattice constants of the thick epilayer agree with the expectation both out-of-plane and in-plane and show nearly complete structural relaxation. An uniaxial in-plane modulation in the thick epilayer has been observed. The out-of-plane and in-plane data of the thin epilayer demonstrate a tetragonal distortion of the lattice, and the Poisson's ratio is calculated to be 0.36. The averaged in-plane lattice constant is still 0.18% larger than that of the substrate, which results in a complex structure at the epitaxial interface. An in-plane misalignment along one (110) axis in the thin epilayer has been observed.
We employ constant temperature molecular dynamics simulations to study, at the atomistic level, the interactions of an Ir tip with a Pb substrate. We have considered the complete cycle of approach.contact, indentation and retraction of the tip from the substrate. We have observed the wetting of the tip by the substrate atoms, and the formation of atomic necking between the tip and the substrate.
We have carried out further simulations to study the interactions of an Ir tip with an Ir substrate covered with an adsorbate monolayer of Pb film. We show that the introduction of the adsorbate considerably reduces the work of adhesion and the extent of plastic flow, in agreement with experimental results.
Three-dimensional geometries have been generated on computer and used for the animation of the simulation runs.
Microwave sintering of Y2O3-2wt.% ZrO2 has produced microstructures which yield mechanical and thermal properties that differ from those observed in commercially sintered Y2O3-2wt.% ZrO2. This paper discusses mechanical and thermal property data obtained on samples of Y2O3-2wt.% ZrO2 heated using 2.45 GHz electromagnetic radiation.
Novel morphologies were produced in phase segmented, toughened epoxies via microwave processing. Novel and exciting chemistries have been demonstrated through the specificity of delivery of electromagnetic radiation in tuned cavities.
This paper presents a process developed at Quest Research Corporation for using microwave energy to join ceramics. It begins with a brief overview of the concept and a recent history of microwave ceramic processing. A mathematical treatment of the microwave heating process then is presented followed by a description of the joining technique, and a summary of the experimental results and joint characterizations. For one set of ceramic samples used, electron microscopy and fracture toughness and hardness measurements were made at the Naval Research Laboratory. Another set of sample material was provided by Coors and photomicrographic evaluations of joints produced by Quest using these samples were performed by Coors.
Results of research on the use of microwave energy for several waste remediation applications are discussed. Studies include; processing of simulated nuclear waste glass frits, the destruction/vitrification of electronic circuitry from commercial and defense applications, the decomposition of organic compounds and the possible use of microwave energy in off-gassing operations during the ashing of electronic circuitry. Results of leach tests on simulated nuclear waste glass are presented as well as results from preliminary tests on organic wastes.
Characterisation and control of the structure and properties of particulate solids suspensions is of widespread importance with respect to many operations, such as separation, dispersion and densification in the ceramics and related industries. In this paper we describe techniques which have been used to study the effects of changes in basic parameters, for example solids content, particle size, electrolyte concentration and added polymer on the aggregated suspension morphology and characteristics. Suspension morphology was examined by a number of methods, notably freeze-etch microscopy. The mechanical properties of suspensions such as their compressional modulus and rheological behaviour was also examined.
Microwave energy for processing materials is emerging as a vital manufacturing technology for the nineties and beyond. Research to date has shown significant advantages in several areas, including drying and sintering, joining, surface modification and waste remediation. Increased processing rates, improved physical and mechanical properties and, in some cases, reduced hazardous emissions have sparked the interest of many manufacturers in the ability to integrate microwave processing techniques into existing and future manufacturing operations. This presentation will provide an overview of the microwave processing research and development work in progress at the University of Florida.