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X-ray microscopy is a field that has developed rapidly in recent years. Two different approaches have been used. Zone plates have been employed to produce focussed beams with sizes as low as 0.07 pm for x-ray energies below 1 keV. Images of biological materials and elemental maps for major and minor low Z have been produced using above and below absorption edge differences. At higher energies collimators and focussing mirrors have been used to make small diameter beams for excitation of characteristic K— or L-x rays of all elements in the periodic
Maize distillers grains (MDG) is a high quality by-product feed containing 317 g crude protein (CP)/kg DM and 13.5 MJ metabolisable energy/kg DM, and as such is a valuable traceable feed resource. An earlier study conducted at the Centre for Dairy Research (Sutton et al. 2000) with cows in late lactation using a total mixed ration (TMR) based on maize silage, compared the protein value of MDG with that of soyabean meal (SB). The study showed that MDG could be used to replace SB on a total nitrogen (TN) basis without effecting feed intake or nutrient digestion in the rumen, or flow of non-ammonia nitrogen to the duodenum. The aim of the current study was to determine the effect of replacing SB with MDG on a TN basis, on DM intake and milk production in high yielding lactating dairy cows.
We present pollen diagrams and sedimentological analyses from a lake site within an extensive dune system on the Aupouri Peninsula, Northland. Five thousand years ago, a regional Agathis australis–podocarp-broadleaf forest dominated the vegetation, which manifested an increasing preponderance of conifer species. Climate was cooler and drier than at present. From ca. 3400 bp, warmth-loving species such as A. australis and drought-intolerant species, Dacrydium cupressinum and Ascarina lucida, became common, implying a warm and moist climate. The pollen record also suggests a windier climate. The most significant event in the record, however, occurred after ca. 900 bp (800 cal bp) when anthropogenic deforestation commenced. A dramatic decline in forest taxa followed, accompanied by the establishment of a Pteridium–esculentum-dominated community. Fire almost certainly caused this, evidenced by a dramatic increase of charcoal. Sedimentological evidence for this site indicates a relatively stable environment before humans arrived and an increasingly unstable environment with frequent erosional events after human contact.
Among the most important stimuli for developing the FLAIR multi-object spectroscopy system on the 1.2-m UK Schmidt Telescope was its potential for carrying out large-scale redshift surveys of galaxies of intermediate magnitude (B <~ 17). During FLAIR’s lengthy development period, these objects provided the yardstick by which the system’s performance was measured, and a number of limited-area redshift surveys were carried out. We are now following these with a 1-in-3 survey over the 60 fields of the ROE/Durham Galaxy Catalogue to produce a redshift map of some 4000 galaxies out to a distance of ~ 300h−1 Mpc (where the parameter h is the Hubble constant expressed as a fraction of 100 kms−1 Mpc−1). In this paper we summarise the results from our redshift surveys to highlight the capabilities of FLAIR. We present a status report on the current large-scale survey, and show that the recently-introduced FLAIR II system will speed its progress considerably.
Monte Carlo simulation of deposition of nonstoichiometric amorphous SiOx nanolayers from vapor phase onto a polymer surface is reported. The model developed is based on the network properties of silica and takes into account dangling bonds arising during the real process of deposition. The model is validated via comparison of the radial- and bond angle distribution functions for the simulated Si and SiO2 structures with those obtained from experiment for bulk materials. Porosity of the simulated amorphous layer is characterized by the relative volume of pores and the ratio of the pore surfaces to the pore volume. We found that porosity strongly depends on nucleation sites density (NSD) on the polymer substrate. At NSD lower than 1 nm−2 the porosity may reach as much as 30% of the layer volume, while at NSD higher than 4 nm−2 it decreases down to 3-7%. Possible implications of the obtained results are discussed.
Charge transport in a composite solar cell (CSC) is analysed by considering independent and random migration of the photo-generated electrons/holes over interpenetrating conducting networks. It is shown that besides an interface area and the materials parameters the efficiency (average number of the carriers reaching the electrode per time unit) of the CSC depends on the effective dimensionality of the conducting channels. Our analysis shows that the 1-d network is ∼20% more effective than the 3-d one, and therefore the morphology of the 1-d type for the organic phase within a 3-d inorganic one is preferable for the CSC. It is shown that the CSC with bulk generation of excitons is potentially more efficient than a dye-sensitised solar cell. The highest efficiency of collection of photo-generated carriers for the CSC at highest possible current for the given material properties cannot exceed ∼40% and 34% for 1-d and 3-d networks respectively.
Over the last two decades the sol gel technique has become very popular because of its ability to yield a multicomponent inorganic glass at low temperatures[1,2]. More recently, techniques to incorporate organic species into a sol gel network of metal alkoxides has been developed and studied[3-7]. One technique developed in our laboratory is to incorporate oligomers endcapped with metal alkoxide functionalities into a reaction mixture of TEOS, water and acid catalyst. The resulting materials, often cured at ambient temperatures, can be tough and transparent monoliths. This technique is important in that it helps to overcome some of the defects of pure sol gel silicate structures such as cracks, voids and brittleness. The high temperature structural properties of these materials, however, are limited because of the organic component. This approach provides the ability to make a wide range of materials with vastly different properties depending upon the polymer and metal alkoxide chosen. Novel properties displayed by these materials make them attractive for certain technological applications such as coatings, films and fibers. One of the main drawbacks of the ambient temperature curing process is the relatively long reaction time which hinders immediate utilisation of the product. As would be expected, the extent of reaction has been found to be dependent on the T, of the oligomer under consideration. In the case of high Tg oligomers (e. g. polysulfones) the reaction has to be completed at elevated temperatures (above the Tg.) in order to acheive a high extent of reaction. In the case of ceramers containing functionalized poly(tetramethyleneoxide) (PTMO) oligomer, curing time can vary between 48 to 100 hours before the final gel can be successfully handled and tested. In order to enhance the rates of reaction and determine the effect of such an acceleration on the physical properties, samples were reacted at elevated temperatures using microwave heating and conventional oven curing. When microwaves were used the curing time has been found in some cases to be reduced dramatically from 60 hours to twenty minutes. In this paper structure-property relationships of these "microwaved" materials will be compared and contrasted with similar materials cured in a conventional oven at equivalent elevated temperatures as well as room temperature cured materials. Time-temperature studies of the reactants were also conducted in a travelling wave guide. These studies were done primarily to gain some insight as to the effect of microwaves on specific reactants. analyzer.
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.
Crystallization of metal-metalloid glasses is known to proceed by nucleation and growth processes. Using crystallization statistics in partially crystallized glasses, at temperatures below the glass transition temperature, time-dependent heterogeneous nucleation has been found to occur at a number of quenched-in nucleation sites . Close to the glass transition temperature crystallization proceeds so rapidly that partially crystallized microstructures could not be obtained. Initial results from fully crystallized glasses exhibit evidence for a transient homogeneous nucleation process at higher temperatures [1,2].
Superconducting ceramics have been successfully prepared employing a novel internal heating mechanism which uses microwave energy. Calcining with microwaves requires further investigation to improve the superconducting properties. Sintering and annealing in microwave energy shows refined microstructure and improved oxygen content in the YBa2Cu3O7-x phase. This is attributed to the coupling of CuO with microwave energy. The onset of the superconductive transition occurs at 93°K for the conventionally calcined/microwave annealed samples. The conventionally processed samples have an onset transition at 90°K and exhibit weaker diamagnetism when compared with the microwave annealed sample.
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.
The Department of Defense (DoD) and the National Aeronautics and Space Administration (NASA) requested that the National Research Council's National Materials Advisory Board conduct a study to assess the current status of microwave processing technology, identify applications of microwave technology where resulting properties are unique or enhanced relative to conventional processing or where significant cost, energy or space savings can be realized, and to recommend future activities in microwave processing. A committee was established to perform the study and report on their findings. This paper is a summary developed from the committee's report, Microwave Processing of Materials (NMAB Report Number 473, Copyright 1994 by the National Academy of Sciences, National Academy Press, Washington, DC).
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.
Optimization of GaN channel conductivity in AlGaN/GaN Heterojunction Field Effect Transistor (HFET) structures was performed using High Resistivity (HR) GaN templates grown by Metal-organic Vapor Phase Epitaxy (MOVPE). The GaN sheet resistance was tuned using final nucleation layer (NL) annealing temperature. Using an annealing temperature of 1033°C, GaN with sheet resistance of 10 Ω/sq was achieved, comparable to that of Fe-doped GaN. X-Ray Diffraction (XRD) and Photoluminescence (PL) analysis show that the high resistance GaN is achieved due to compensating acceptor levels introduced through edge-type threading dislocations. XRD analysis also shows optimization of annealing temperature provided a means to maximize GaN sheet resistance without significantly degrading material quality. AlGaN/GaN HFET layers grown using HR GaN templates gave surface and interface roughness of 14 and 7 Å, respectively. The 2DEG Hall mobility and sheet charge of HFETs grown using HR GaN templates was comparable to similar layers grown using unintentionally doped (UID) GaN templates.
Several theories have posited a common internalizing factor to help account for the relationship between mood and anxiety disorders. These disorders are often co-morbid and strongly covary. Other theories and data suggest that personality traits may account, at least in part, for co-morbidity between depression and anxiety. The present study examined the relationship between neuroticism and an internalizing dimension common to mood and anxiety disorders.
A sample of ethnically diverse adolescents (n=621) completed self-report and peer-report measures of neuroticism. Participants also completed the Structured Clinical Interview for DSM-IV (SCID).
Structural equation modeling showed that a single internalizing factor was common to lifetime diagnosis of mood and anxiety disorders, and this internalizing factor was strongly correlated with neuroticism. Neuroticism had a stronger correlation with an internalizing factor (r=0.98) than with a substance use factor (r=0.29). Therefore, neuroticism showed both convergent and discriminant validity.
These results provide further evidence that neuroticism is a necessary factor in structural theories of mood and anxiety disorders. In this study, the correlation between internalizing psychopathology and neuroticism approached 1.0, suggesting that neuroticism may be the core of internalizing psychopathology. Future studies are needed to examine this possibility in other populations, and to replicate our findings.
We consider the reinterpretation of Bethia by Bassett et al. (2008) to be flawed in several regards. Details of the pedicle rootlets and wrinkles strongly imply a soft-tissue structure rather than calcified sheath. The ornament is unusual, but equally so under either an orthide or a plectambonitoidean model. The reinterpretation of the ‘deltial plates’ as ‘chilidial plates’ is likely correct, but argues against a plectambonitoidean affinity by implying that the pedicle emerges between the valves. Other arguments presented in favour of a plectambonitoidean affinity are also discussed; we consider them unpersuasive. Finally, we contend that Bethia is sufficiently well characterised to deserve a taxonomic name.
Covering an area of 177,000 hectares, the region known within Belize as the Chiquibul Forest comprises the country's largest forest reserve and includes the Chiquibul Forest Reserve, the Chiquibul National Park and the Caracol Archaeological Reserve. Based on 7047 herbarium and live collections, a checklist of 1355 species of vascular plant is presented for this area, of which 87 species are believed to be new records for the country. Of the 41 species of plant known to be endemic to Belize, four have been recorded within the Chiquibul, and 12 species are listed in The World Conservation Union (IUCN) 2006 Red List of Threatened Species. Although the Chiquibul Forest has been relatively well collected, there are geographical biases in botanical sampling which have focused historically primarily on the limestone forests of the Chiquibul Forest Reserve. A brief review of the collecting history of the Chiquibul is provided, and recommendations are given on where future collecting efforts may best be focused. The Chiquibul Forest is shown to be a significant regional centre of plant diversity and an important component of the Mesoamerican Biological Corridor.
Six multiparous Holstein-Friesian cows were offered a total mixed ration based on maize silage in a repeated measure design to evaluate the partition of gross energy (GE) during early to mid lactation. Four measurements were made at 6-week intervals with energy and nitrogen balances carried out in open-circuit respiration chambers over 6 days during lactation weeks 6, 12, 18 and 24. The intakes of total diet dry matter (DM) corrected for volatile losses (VCDM), organic matter (OM) and GE declined significantly (P < 0•01) as lactation progressed, although apparent digestibility of these fractions was not altered, resulting in a significant (P < 0•01) decline in digestible nutrient intake at each stage of lactation. Methane and urine energy losses were not significantly affected, resulting in significantly (P < 0·001) higher amounts of digestible energy (DE) partitioned to methane and urine as lactation progressed with associated significant reductions in metabolizable energy (ME) intake (MEI) (P < 0·01) and ME as a proportion of DE (P < 0·001) and GE (q) (P < 0·05). With advancing lactation there was a significant (P < 0·001) increase in the amount of ME partitioned to heat (HP/MEI), but no significant change in the amount partitioned to milk and tissue. Individual values for diet metabolizability (ME/GE) at actual (production) levels (qa) (mean 0·625 MJ/MJ) were corrected to an equivalent value at maintenance (qmc) (mean 0·666 MJ/MJ). The overall ME intakes (MJ/day) were: ad libitum, 246, corrected for level of feeding effect, 263, with a predicted ME requirement according to AFRC (1993) (MER93) of 242. Substitution of the calculated qmc into the predictive equations (AFRC, 1993) resulted in a mean maintenance requirement of 57·6 MJ/day (0·464 MJ/kg M0·75/day) whilst the mean value derived from the linear model describing the experimental data was 82·5 MJ/day (0·664 MJ/kg M0·75/day). The mean efficiencies of utilization of ME for milk production derived from AFRC (1993) and the linear regression model were 0·653 MJ/MJ and 0·625 MJ/MJ respectively.