[en] Physics and detector simulations at the Superconducting Super Collider Laboratory (SSCL) are performed on a heterogeneous network of RISC based workstations named the Physics and Detector Simulation Facility (PDSF). These simulations can be characterized by the consumption and generation of large amounts of data. It is clear that on-line disk storage must be supplemented by off-line tape storage. For the PDSF, an 8-mm tape robot system was initially chosen in order to provide tertiary data storage based on its compactness and low cost. In order to manage this data, the Physics Computing Department designed the Data Management System (DMS)

[en] The potential use of different iron phosphates as cathode materials in lithium-ion batteries has recently been investigated.1 One of the promising candidates is LiFePO4. This compound has several advantages in comparison to the state-of-the-art cathode material in commercial rechargeable lithium batteries. Firstly, it has a high theoretical capacity (170 mAh/g). Secondly, it occurs as mineral triphylite in nature and is inexpensive, thermally stable, non-toxic and non-hygroscopic. However, its low electronic conductivity (∼10-9 S/cm) results in low power capability. There has been intense worldwide research activity to find methods to increase the electronic conductivity of LiFePO4, including supervalent ion doping,2 introducing non-carbonaceous network conduction3 and carbon coating, and the optimization of the carbon coating on LiFePO4 particle surfaces.4 Recently, the Li doped LiFePO4 (Li1+xFe1-xPO4) synthesized at ARL has yield electronic conductivity increase up to 106.5 We studied electronic structure of LiFePO4 and Li doped LiFePO4 by synchrotron based soft X-ray emission (XES) and X-ray absorption (XAS) spectroscopies. XAS probes the unoccupied partial density of states, while XES the occupied partial density of states. By combining XAS and XES measurements, we obtained information on band gap and orbital character of both LiFePO4 and Li doped LiFePO4. The occupied and unoccupied oxygen partial density of states (DOS) of LiFePO4 and 5 percent Li doped LiFePO4 are presented in Fig. 1. Our experimental results clearly indicate that LiFePO4 has wideband gap (∼ 4 eV). This value is much larger than what is predicted by DFT calculation. For 5 percent Li doped LiFePO4, a new doping state was created closer to the Fermi level, imparting p-type conductivity, consistent with thermopower measurement. Such observation substantiates the suggestion that high electronic conductivity in Li1.05Fe0.95 PO4 is due to available number of charge carriers in the material. Furthermore, Hall effect measurement on Li doped sample confirmed presence of free charge carriers, which are responsible for the observed electronic conductivity increase in Li doped LiFePO4. There is no evidence that Fe3+valence is created by doping with excessive Li+ in Li1.05Fe0.95PO4, as shown by Fe-edge XAS. (Fig.2) Instead, charge-carrier holes reside primarily in unoccupied O 2p states, which compensate for the charge deficiency from Li+ substitution for Fe2+. The increased conductivity in Li1.05Fe0.95PO4 is attributed to the new charge carriers (doped holes)and the strong electron correlation between O 2p and Fe 3d states

[en] The magnetic behaviour of the 58 K superconductor oxycarbonate thin film, which consists of an intergrowth of several members of a family with agreement composition (CaCuO₂)_m(Ba₂CuCO₃O₂)n has been studied. Its pinning properties in terms of critical current densities and irreversibility line have been established using their hysteresis cycles. Typical J_c was calculated to approximately 10⁵ A cm^-2 at 5 K in zero field. Finally, the irreversibility line is compared to those obtained by Kumakura et al. (1994) on bulk oxycarbonate superconductors synthesized at high pressure. (author)

[en] Prostaglandins of the E series increase stomach mucosal mass by inducing hyperplasia, which could be the result either of increased cell production or of decreased cell loss. This report describes an investigation of the effect of the prostaglandin E1 analogue, misoprostol, on cell migration and transit. 3H-thymidine was used to label those cells synthesizing deoxyribonucleic acid in dogs that had been given an oral dose of 300 micrograms/kg per day misoprostol for 11 weeks. The animals were killed at timed intervals, and tissue from the gastric fundus was prepared for autoradiography. The distribution of labeled cells at various times after labeling was used to follow the movement of the wave of label and to calculate median cell migration rates and transit times. The migration rate of cells toward the gastric lumen was significantly increased from 1.4 +/- 0.3 to 3.6 +/- 0.6 cell positions per day in the misoprostol-treated group (p less than 0.001); however, the gland length (from the most basal mucous neck cell to the luminal surface) was also increased (from 52.1 +/- 1.1 to 74.0 +/- 1.6; p less than 0.001), thus there was no significant difference in the (transit) time taken for cells to reach the top of the gland (control, 17.5 +/- 9.8 days; test, 12.2 +/- 7.1 days)

[en] Full text: For the first time, large single crystals of the simplest amino acid, glycine, have been used to measure the temperature dependence of its terahertz spectrum. Use of the single crystal morphology at cryogenic temperatures has allowed for particularly high-quality spectra with very sharp absorption features in the terahertz region. A solution of 30mL of distilled water and 7g of glycine was heated to 50°C while being continuously stirred until all the solvent was dissolved, following the solvent evaporation method for crystals [1]. Crystals were allowed to grow in the solution at room temperature over three days, resulting in a 10×5mm crystal for spectroscopy. Previous studies such as [2], and the references therein, have used pelletised blends. The single crystal approach of this work removes the potential of observing extrinsic interactions caused by these pelletised binding media. The spectra have been measured using Fourier transform spectroscopy (FTS: Bomem DA8) in the range 30-250cm^-1, and terahertz time-domain spectroscopy (THz-TDS: TeraView TeraPulse 4000) for validation of the range 20-100cm^-1. This was done over a temperature range of 290-20K. Spectra below 150K were taken while warming the sample, and spectra above 150K were taken while cooling. The results in Fig. 1 show 7 total absorption bands. The first 3 absorption bands observed with both instruments red-shift with increasing temperature. These are seen at 50cm^-1 (shifting by 3.1cm^-1 from 20-216K), 69cm^-1 (shifting by 0.3cm^-1 from 20-235K), and at 92cm^-1 with a weak shoulder. A further 4 absorption bands are seen with the FTS system but are too absorptive to precisely locate the peak positions. Approximate peaks are at 145cm^-1, 150cm^-1, 185cm^-1, and 222cm^-1. The use of a single crystal sample, with purity validated by X-ray diffraction, accurately gives the intrinsic terahertz spectral features of glycine, and their temperature dependences. (author)

[en] Full text: Plastics present a major challenge of the 21st century as they are prolific but produced from a non-renewable source (crude oil) and can cause many environmental problems. While reducing the global reliance on plastics is part of the solution, plastics are still necessary in some fields, for example in preserving sterile medical supplies. Thus, improving current recycling methods is still a valuable endeavour. Terahertz spectroscopy is a maturing technique for probing the vibrational modes of materials in a non-ionising, non-destructive manner that may be used to discern different plastic samples. Firstly, characteristic features need to be identified that can be used as markers to distinguish different plastics. This work focuses on identifying these characteristic features in polyethylene terephthalate (PET) by studying the terahertz spectrum. Spectra have been collected on the terahertz beamline at the Australian Synchrotron. Fourteen samples of PET plastic from everyday household items have been studied, discerned by their plastics identification code, along with a commercially purchased biaxially orientated sample (BO-PET). The BO-PET sample is more crystalline than standard PET and acts as a reference point for the other samples studied. The samples have been investigated in a variety of ways to determine the suitability of terahertz spectroscopy in their spectroscopic identification. Firstly, the most intense terahertz source of radiation has been used. Next, low temperatures and polarisation dependence have been investigated for additional insight into the spectra. The results, summarised in Fig. 1, show that while there is much variety in commercial PET, there are common absorptions. These features can be used to identify PET amongst other plastics. (author)

[en] The development of lipid aspiration pneumonia after chronic nasopharyngeal installation of mineral oil was first described in 1925 by Laughlin. Since that time this entity has been well recognized and numerous substances have been identified or implicated as the aspirated material. The classic radiographic appearance of severe chronic lipid aspiration pneumonia has been described as consisting of intense perihilar infiltrates. However, the radiographic findings are more often non-specific and usually consist of varying degrees of diffuse interstitial infiltrates that tend to be more prominent in the perihilar regions and the right lung. We are reporting a case of biopsy-proven lipid aspiration pneumonia in an infant with known gastro-esophageal reflux (GER) who had medium-chain triglyceride oil administered via nasogastric tube. Serial roentgenograms demonstrated a changing pulmonary pattern from diffuse bilateral interstitial infiltrates initially to a diffuse alveolar pattern at the time of the lung biopsy. Modern medicine has developed new methods for providing nourishment to sick newborns and infants to improve their nutritional status and help them to grow. One such method involves the administration of medium-chain triglycerides (MCT oil) into the GI tract via a nasogastric or nasoenteral tube. The purpose of this report is to describe a significant complication of this method of providing nutrition to an infant with gastroesophageal reflux (GER) and the diagnostic dilemma it presented. (orig.)

[en] High-spin states in the doubly-odd nuclei ^154,156Tb have been populated in two separate experiments using the ³⁶S+¹²⁴Sn reaction at different beam energies (160 and 175 MeV). The yrast structures of both nuclei were extended to much higher spin (I≤48ℎ) than previously known and several quasiparticle alignments have been identified. These include the second neutron alignment and a clear delineation of the second proton crossing in ¹⁵⁶Tb. Systematics of these crossings for odd-Z nuclei and comparisons with results of cranked shell model calculations are discussed. thinsp copyright 1999 The American Physical Society

[en] Full text: Exotic quantum states such as spin-liquid, spin-ice, and spin-glass phases [1,2,3] have been revealed through investigations of frustrated and quantum magnetic systems, intensifying recent interest in such systems. The natural mineral atacamite, Cu₂Cl(OH)₃, represents a low dimensional quantum frustrated magnet [4] with similarity to spin-liquid systems. Atacamite has a complex magnetic phase diagram [5], however, the transitional dynamics and the spin structures of its various magnetic phases are not yet completely understood. Many experimental techniques can be applied to characterise the complex magnetic properties of a magnetic system. Magnetisation, susceptibility, specific heat, neutron diffraction, inelastic neutron scattering, and terahertz (THz) spectroscopy have all been applied to atacamite with the goal of describing its magnetic properties and phases. This work gives a comprehensive overview of both the experimental and theoretical techniques used to determine the magnetic exchange structure of atacamite, with a focus on the experimental techniques of inelastic neutron scattering and THz spectroscopy. Theoretical density functional theory (DFT) modelling has been performed to calculate the exchange interactions in atacamite. However, empirical results are needed to validate these calculations. Thus, several candidate exchange structure models have been developed from the DFT calculations, and tested against inelastic neutron scattering measurements of atacamite’s spin-waves through linear spin-wave theory, revealing a promising exchange structure. Despite the recent curiosity in atacamite, little is known about its optical spectra in the THz energy region, which corresponds to where magnetic spin-wave modes are often observed in magnetic systems [6,7]. Recent THz measurements have attempted to reveal spin-wave modes, however, evidence for structural phase transitions was found in the spectral temperature dependence of atacamite, highlighting the complex dynamics of the system.(author)