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  • 1
    Electronic Resource
    Electronic Resource
    Study of diamond thin-film growth mechanism in a filament-assisted excimer laser ablation system (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 8113-8116 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamond and amorphous carbon films have been deposited on silicon (100) substrates by filament-assisted XeCl excimer laser ablation of graphite targets. The influence of process parameters on the growth mechanism of diamond were studied by depositing films over a wide range of gas pressures and substrate temperatures. The surface morphology and bonding of the deposited films were characterized by scanning electron microscopy, and Raman and electron-energy-loss spectroscopy. In these experiments, microcrystalline diamond films with growth rates comparable to conventional chemical-vapor-deposition and plasma-enhanced chemical-vapor-deposition techniques could only be obtained at substrate temperatures and hydrogen pressures greater than 700 °C and 1.3 mbar, respectively. Conversely, the best conditions for growing carbon films with predominately sp3-type bonding structures were at temperatures and pressures less than 300 °C and 0.3 mbar, respectively. These results suggest that carbon-hydrogen gas phase reactions as well as gas-surface reactions are both necessary for the formation of diamond. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357860
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  • 2
    Electronic Resource
    Electronic Resource
    Dielectric properties of BaTiO3/SrTiO3 multilayered thin films prepared by pulsed laser deposition (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 1394-1396 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: BaTiO3/SrTiO3 multilayered thin films were deposited on Si and Pt/Si substrates. X-ray diffraction clearly shows the formation of the superstructures. Phase transition properties were studied via dielectric measurements. Glassy behavior, characterized by a strong frequency dispersion of dielectric properties, was found in samples with a total thickness of 400 nm, while in samples with a total thickness of 800 nm, normal ferroelectric phase transitions with two dielectric peaks were observed. A preliminary interpretation assumes that size effects which frustrate long range ferroelectric ordering may lead to the relaxational behavior in BaTiO3/SrTiO3 superstructures. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121066
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  • 3
    Electronic Resource
    Electronic Resource
    Production and structural characterization of BN/TiN multilayers (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 1235-1244 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A pulsed excimer laser was used to evaporate targets of boron nitride and titanium nitride in an attempt to produce hard thin films on crystalline silicon substrates. The films were either pure TiN or BN layers, as well as alternating multilayers and mixed layers. Deposition could be assisted by ion bombardment. The films were characterized by Auger electron spectroscopy, Fourier transform infrared spectroscopy (FTIR), and x-ray diffraction. A selection of films was also studied by profilometry in order to determine deposition rate and the type of stress present. The level of stress in TiN films was also a function of the deposition temperature and could be varied with the use of ion bombardment. Amorphous, cubic, and hexagonal BN films were produced and the effect of the stress of the substrate on these layers was investigated. Multilayers were stressed, having alternating layers of nanocrystalline TiN and amorphous BN. Mixtures consisted of nanometer-sized regions of crystalline TiN and sp2 coordinated boron nitride. FTIR spectra and high-resolution transmission electron microscope pictures suggested that in the mixtures, boron nitride planes tended to parallel the surface of the TiN grains. No sign of stress-driven formation of cubic BN was observed in the multilayers nor in the nanosized mixtures, regardless of the stress level present in them; neither was there any sign of titanium borides or other structures that might increase the hardness of the films. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372002
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  • 4
    Electronic Resource
    Electronic Resource
    17β-estradiol suppresses gene expression of tartrate-resistant acid phosphatase and carbonic anhydrase II in ovariectomized rats (1995)
    Springer
    Calcified tissue international 56 (1995), S. 166-169 
    Details
    ISSN: 1432-0827
    Keywords: Tartrate-resistant acid phosphatase ; Carbonic anhydrase II ; Gene expression ; Estrogen ; Ovariectomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Tartrate-resistant acid phosphatase (TRACP) and carbonic anhydrase II (CA II) are key enzymes responsible for osteoclastic bone resorption. In this study, we proposed that estrogen loss in postmenopausal osteoporosis may enhance gene expression of TRACP and CA II, and subsequently increase osteoclastic bone resorption. We have, therefore, used the ovariectomized rat model of postmenopausal bone loss to investigate changes at the gene transcripional level in osteoclastic bone-resorbing enzymes in ovariectomized (OVX) rats, sham ovariectomized (S-OVX) rats, and estrogen-treated ovariectomized (E-OVX) rats. We have demonstrated for the first time that ovariectomy in rats enhances gene expression of TRACP and CA II. The mRNA levels in OVX were approximately three- and four-fold higher, respectively, than those in S-OVX. Enhancement was observed 1 week after ovariectomy and transcripts remain high during the experimental period of 8 weeks. Administration of 17β-estradiol to OVX (E-OVX) reduced gene expression of these osteoclastic bone-resorbing enzymes 18 hours after injection. It appeared that the suppression of the osteoclastic bone-resorbing enzymes by 17β-estradiol was most effective during the first 1–2 weeks but the degree of suppression was reduced at 8 weeks after ovariectomy. In conclusion, our results suggest that estrogen prevents bone loss by reducing the mRNA levels of osteoclastic bone-resorbing enzymes in bone tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296350
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  • 5
    Electronic Resource
    Electronic Resource
    The Effect of Estrogen Deficiency on Bone Mineral Density, Renal Calcium and Phosphorus Handling and Calcitropic Hormones in the Rat (1996)
    Springer
    Calcified tissue international 59 (1996), S. 174-178 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Oophorectomized rat — Calcitropic hormones — Calcium — Phosphorus — Kidney — Bone mineral density.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The oophorectomized (OOX) rat has been proposed as a good model of postmenopausal osteroporosis in women. The aim of this study was to compare the effect of OOX in 6-month-old rats to the effects of menopause in women with respect to bone mass, the renal handling of calcium and phosphorus, and calcitropic hormones. To more closely replicate the human situation the rats were pair fed a 0.1% calcium diet. Thirty four, 6-month-old rats were randomized to sham operation or OOX. Whole body and regional bone density was performed at baseline and 6 weeks postoperation. Blood and 24-hour urine samples were obtained at baseline, 1, 3, and 6 weeks and assayed for various biochemical variables, parathyroid hormone (PTH), and calcitriol. The OOX rats lost significantly more bone than the sham-operated rats (change in global bone mineral density, sham −1.7 ± 2.0%, OOX −3.9 ± 2.6%, P 〈 0.001). In the OOX animals, an increase in the 24-hour urine calcium was observed at 1 and 3 weeks, which had returned to sham-operated levels by 6 weeks. In the whole group, the increase in urine calcium at 1 week was negatively correlated with the change in bone mass at 6 weeks (r =−0.39, P= 0.029). OOX resulted in an increased filtered load of calcium and phosphorus. There was an increase in the maximal renal tubular reabsorption of phosphorus (TmP-GFR) but no clear change in renal calcium handling. Neither calcitriol nor parathyroid hormone showed a significant change as a result of OOX. As in postmenopausal women, following oophorectomy in the rat, there was significant generalized bone loss and a negative calcium balance. This was associated with an initial rise in urine calcium due to a rise in the filtered calcium load; plasma phosphorus and TmP-GFR also rose. The rat model may differ from postmenopausal bone loss in that the initial rise in urine calcium was not present at later time points as occurs in natural menopause in women. Calcitropic hormone levels did not change. This study has shown that the 6-month-old OOX rat fed a 0.1% calcium diet has many similarities of calcium and phosphorus homeostasis to that seen at menopause in women.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900105
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  • 6
    Electronic Resource
    Electronic Resource
    Practice Guidelines for the Treatment of Osteoporosis (1996)
    Springer
    Calcified tissue international 59 (1996), S. S020 
    Details
    ISSN: 1432-0827
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. History will probably describe this as a significant era for osteoporosis management, which has recently shifted from the laboratory and research clinic into mainstream clinical practice. It is timely, therefore, to provide practice guidelines for clinical use in this area; they must be developed carefully, however, so as to ensure that they are generated from reliable data. Furthermore, in current circumstances, management not only must be effective but also must aim for cost minimization; this is a difficult area in which little information is available. Also, in light of increased knowledge about skeletal medicine, complex cases should be considered for referral to an expert. The diagnosis of osteoporosis centers on two main steps: the identification of patients at risk and the estimation of bone density at two skeletal sites to help in ascertaining future fracture risk. At present, the main question in this approach centers on identifying the risk level threshold at which bone density should be evaluated. Although it is generally agreed that anyone with an atraumatic osteoporotic fracture will benefit from bone density estimation, the exact risk level for other, less easily defined indicators (e.g., cigarette smoking) is unclear. Once the diagnosis of osteoporosis is made, the cause must be elucidated by appropriate biochemical and imaging techniques. Appropriate therapy varies with the cause and level of risk. Although many treatments are currently available, including pharmacologic intervention, dietary changes, and exercise, they must be selected and adapted according to the needs of the individual patient, a process requiring both skill and patience.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900171
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  • 7
    Electronic Resource
    Electronic Resource
    The Effect of Estrogen Deficiency on Calcium Balance in Mature Rats (1999)
    Springer
    Calcified tissue international 64 (1999), S. 325-328 
    Details
    ISSN: 1432-0827
    Keywords: Keywords: Calcium balance — Estrogen deficiency — Rats — Intestine.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The role of estrogen in the regulation of calcium balance is still poorly understood. A calcium balance study was performed to examine the effects of estrogen status in relation to fecal calcium loss as a component of bone loss after oophorectomy (OOX) in the mature rat. The components of the classic calcium balance were compared with calcium balance estimates obtained from whole body bone density. Six month or older Sprague Dawley rats were allocated to either a sham-operated or OOX group and fed a 0.1% calcium diet. The bone mineral density (BMD) and bone mineral content (BMC) were measured at baseline, 6 weeks, and 9 weeks. A calcium balance was done for 6 days before and 6 weeks post OOX. The fall in BMD from baseline to 9 weeks in the OOX group was significantly greater than in the sham-operated group. The calcium balance was more negative at baseline than at 6 weeks in both groups of animals because they had not adapted to the low calcium diet. However, the increase in calcium balance was significantly less in the OOX animals than in the sham-operated animals. The greater the rise in calcium balance from the baseline to the 6 weeks balance the less the fall in the calcium content of the whole body (Spearman correlation: r = 0.604 P = 0.008). The fall in fecal calcium, but not urine calcium or calcium consumed, was negatively correlated with the change in whole body BMC (Spearman correlation: fecal calcium r =−0.763 P = 0.001). Thus, the primary effect of estrogen deficiency on calcium balance in the mature rat appears to be calcium flux in the bowel, rather than renal calcium handling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900627
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  • 8
    Electronic Resource
    Electronic Resource
    Elemental composition of a tusk of a dugong, Dugong dugon, from Exmouth, Western Australia (1997)
    Springer
    Marine biology 129 (1997), S. 203-214 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Element analysis of the annual increments in a longitudinal section from the tusk of a female dugong Dugong dugon (Müller) from Exmouth, Western Australia, was carried out by X-ray fluorescence-imaging, inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS). Nine elements (Ba, Ca, Fe, Li, Mg, Na, P, Sr and Zn) were present in concentrations amenable to determination by these techniques. Most elements revealed both long-term trends and shorter, year-to-year, variations. For example, sodium concentrations increased from 0.55 to 0.72% with the age of the dugong. Strontium concentrations (mean 0.17%) were closely correlated (r = 0.86) with those of barium (mean 4.5 mg kg−1). Zinc concentrations increased from ∼70 to 170 mg kg−1 with dugong age, but also showed shorter-term fluctuations of ∼30 mg kg−1 that were correlated (r = 0.41) with mean annual Fremantle sea level (a measure of the Southern Oscillation Index and strength of the Leeuwin Current). The concentrations of the elements and correlations with year and between pairs of elements are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050161
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  • 9
    Electronic Resource
    Electronic Resource
    Experimental linkage issues of petroleum site bioremediation (1993)
    Springer
    Biodegradation 4 (1993), S. 207-230 
    Details
    ISSN: 1572-9729
    Keywords: analytical chemistry ; bioassay ; biochemistry ; composition ; hydrocarbons ; remediation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Bioremediation of petroleum-contaminated sites is expected to be a cost-effective remediation technology. However, many potential users of the technology expect the reliability of this technology to be similar to other candidate technologies for widespread consideration. In particular, candidate technologies should possess the property of reliable experimental linkage — there should be reasonable confidence that experiments done at one scale can be reliably related to another. An important example is bench-scale treatability studies that should result in linkages with commercial-scale operations. In this respect comparison of bioremediation to other candidate technologies reveals that bioremediation is in an early stage of its evolution. It is being pursued at a variety of sites and scales with practitioners from a variety of disciplines. Integration of activities between disciplines and an ability to quantitatively compare results at different sites and scales is proceeding. This paper addresses a number of physical, chemical, biological, analytical, and statistical issues regarding the successful comparison of results between experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00695970
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  • 10
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    Genetic determinants of heel bone properties: genome-wide association meta-analysis and replication in the GEFOS/GENOMOS consortium (2014)
    Moayyeri, A., Hsu, Y.-H., Karasik, D., Estrada, K., Xiao, S.-M., Nielson, C., Srikanth, P., Giroux, S., Wilson, S. G., Zheng, H.-F., Smith, A. V., Pye, S. R., Leo, P. J., Teumer, A., Hwang, J.-Y., Ohlsson, C., McGuigan, F., Minster, R. L., Hayward, C., Olmos, J. M., Lyytikainen, L.-P., Lewis, J. R., Swart, K. M. A., Masi, L., Oldmeadow, C., Holliday, E. G., Cheng, S., van Schoor, N. M., Harvey, N. C., Kruk, M., del Greco M, F., Igl, W., Trummer, O., Grigoriou, E., Luben, R., Liu, C.-T., Zhou, Y., Oei, L., Medina-Gomez, C., Zmuda, J., Tranah, G., Brown, S. J., Williams, F. M., Soranzo, N., Jakobsdottir, J., Siggeirsdottir, K., Holliday, K. L., Hannemann, A., Go, M. J., Garcia, M., Polasek, O., Laaksonen, M., Zhu, K., Enneman, A. W., McEvoy, M., Peel, R., Sham, P. C., Jaworski, M., Johansson, A., Hicks, A. A., Pludowski, P., Scott, R., Dhonukshe-Rutten, R. A. M., van der Velde, N., Kahonen, M., Viikari, J. S., Sievanen, H., Raitakari, O. T., Gonzalez-Macias, J., Hernandez, J. L., Mellstrom, D., Ljunggren, O., Cho, Y. S., Volker, U., Nauck, M., Homuth, G., Volzke, H., Haring, R., Brown, M. A., McCloskey, E., Nicholson, G. C., Eastell, R., Eisman, J. A., Jones, G., Reid, I. R., Dennison, E. M., Wark, J., Boonen, S., Vanderschueren, D., Wu, F. C. W., Aspelund, T., Richards, J. B., Bauer, D., Hofman, A., Khaw, K.-T., Dedoussis, G., Obermayer-Pietsch, B., Gyllensten, U., Pramstaller, P. P., Lorenc, R. S., Cooper, C., Kung, A. W. C., Lips, P., Alen, M., Attia, J., Brandi, M. L., de Groot, L. C. P. G. M., Lehtimaki, T., Riancho, J. A., Campbell, H., Liu, Y., Harris, T. B., Akesson, K., Karlsson, M., Lee, J.-Y., Wallaschofski, H., Duncan, E. L., O'Neill, T. W., Gudnason, V., Spector, T. D., Rousseau, F., Orwoll, E., Cummings, S. R., Wareham, N. J., Rivadeneira, F., Uitterlinden, A. G., Prince, R. L., Kiel, D. P., Reeve, J., Kaptoge, S. K.
    Oxford University Press
    Details
    Publication Date: 2014-05-09
    Description: Quantitative ultrasound of the heel captures heel bone properties that independently predict fracture risk and, with bone mineral density (BMD) assessed by X-ray (DXA), may be convenient alternatives for evaluating osteoporosis and fracture risk. We performed a meta-analysis of genome-wide association (GWA) studies to assess the genetic determinants of heel broadband ultrasound attenuation (BUA; n = 14 260), velocity of sound (VOS; n = 15 514) and BMD ( n = 4566) in 13 discovery cohorts. Independent replication involved seven cohorts with GWA data ( in silico n = 11 452) and new genotyping in 15 cohorts ( de novo n = 24 902). In combined random effects, meta-analysis of the discovery and replication cohorts, nine single nucleotide polymorphisms (SNPs) had genome-wide significant ( P 〈 5 x 10 –8 ) associations with heel bone properties. Alongside SNPs within or near previously identified osteoporosis susceptibility genes including ESR1 (6q25.1: rs4869739, rs3020331, rs2982552), SPTBN1 (2p16.2: rs11898505), RSPO3 (6q22.33: rs7741021), WNT16 (7q31.31: rs2908007), DKK1 (10q21.1: rs7902708) and GPATCH1 (19q13.11: rs10416265), we identified a new locus on chromosome 11q14.2 (rs597319 close to TMEM135 , a gene recently linked to osteoblastogenesis and longevity) significantly associated with both BUA and VOS ( P 〈 8.23 x 10 –14 ). In meta-analyses involving 25 cohorts with up to 14 985 fracture cases, six of 10 SNPs associated with heel bone properties at P 〈 5 x 10 –6 also had the expected direction of association with any fracture ( P 〈 0.05), including three SNPs with P 〈 0.005: 6q22.33 (rs7741021), 7q31.31 (rs2908007) and 10q21.1 (rs7902708). In conclusion, this GWA study reveals the effect of several genes common to central DXA-derived BMD and heel ultrasound/DXA measures and points to a new genetic locus with potential implications for better understanding of osteoporosis pathophysiology.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
    Published by Oxford University Press
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