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  • 1
    Electronic Resource
    Electronic Resource
    Photoacoustic investigation of resonance absorption on corrugated surfaces (1996)
    Springer
    Applied physics 62 (1996), S. 263-268 
    Details
    ISSN: 1432-0630
    Keywords: 78.20. — e ; 41.20. — q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The PhotoAcoustic (PA) method has been used to study the optical resonance absorptions on corrugated surfaces. The resonance absorptions due to the excitations of surface plasmons and guide-waves of corrugated surfaces have been measured experimentally, and the effects of the groove depth and period of the corrugated surface on the absorption curve have been observed. Moreover, the differential method based on the rigorous use of electromagnetic theory is used to calculate the parameters of the grooves and the optical absorptivities of the samples. The theoretical results on the resonance absorption peaks are in good agreement with those of the PA experiments. Then, the parameters of the grooves can be estimated by the PA investigations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01575092
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  • 2
    Electronic Resource
    Electronic Resource
    Structural and gas-sensing properties of nanometre tin oxide prepared by PECVD (1996)
    Springer
    Journal of materials science 7 (1996), S. 279-282 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A low-temperature plasma-enhanced chemical vapour deposition (PECVD) technique has been employed to produce ultrafine tin oxide powders. The structural features and phase transition of this material have been characterized using differential thermal analysis (DTA), thermogravimetric analysis (TGA), X-ray diffraction, infrared spectroscopy (IR) and transmission electron microscopy (TEM). The oxygen absorption behaviour and gassensing properties have been investigated by electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS) and electrical measurements. Thick film gas sensors made from such ultrafine SnO2 powders yield better sensitivities than those of normal undoped SnO2 gas sensors. A gas-sensing reaction mechanism is also proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00188955
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  • 3
    Electronic Resource
    Electronic Resource
    Calcitonin Provides Complete Protection Against Cancellous Bone Loss in the Femoral Neck of Ovariectomized Rats (1997)
    Springer
    Calcified tissue international 60 (1997), S. 457 -461 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Cancellous bone — Histomorphometry — Calcitonin — Femoral neck — Ovariectomy.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Calcitonin (CT) has been found to partially prevent cancellous bone loss in the proximal tibia of ovariectomized (OVX) rats. The current study was designed to determine whether CT has similar bone protective effects in the femoral neck, a skeletal site with a slower rate of bone loss after ovariectomy than the proximal tibia. Female Sprague Dawley rats were sham-operated or ovariectomized at 3 months of age. Groups of OVX rats were injected s.c. with vehicle or CT at a dose of 16 U/kg body weight on alternate days for 30, 60, or 90 days. Sham-operated control rats were treated with vehicle alone on alternate days. The proximal femur from each rat was processed undecalcified for quantitative bone histomorphometry. Cancellous bone volume in the femoral neck of vehicle-treated OVX rats was significantly less than that of vehicle-treated control rats at all time points. This cancellous osteopenia induced by ovariectomy was associated with increased indices of bone turnover such as osteoclast surface, osteoblast surface, and bone formation rate (tissue level, total surface referent). In contrast, cancellous bone volume in the femoral neck of CT-treated OVX rats was nearly identical of that of vehicle-treated control rats throughout the study. In addition, CT treatment of OVX rats decreased all indices of bone turnover to near the level of vehicle-treated control rats. The results indicate that CT treatment depresses bone turnover and provides complete protection against moderate cancellous osteopenia in the femoral neck of OVX rats. Since previous studies have shown that CT only partially protects against more pronounced cancellous bone loss in the proximal tibia of OVX rats, our findings suggest that CT has a greater bone protective effect at a skeletal site with a slower rate of cancellous bone loss (femoral neck) than at a skeletal site with a rapid rate of cancellous bone loss (proximal tibia).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900262
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  • 4
    Electronic Resource
    Electronic Resource
    Column wall modifications using polyethylene oxide for capillary electrophoresis of ribonucleotides (1999)
    Springer
    Chromatographia 49 (1999), S. 299-305 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Column technology ; Deactivation ; Polyethyleneoxides ; Ribonucleotides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In this study, a variety of fused silica capillaries with different combinations and sequences of treatments with HMDS and polyethylene oxide were prepared in order to develop an optimized column modification method for analysis of ribonucleotides. The 12 most common ribonucleotides (UTP, CTP, ATP, GTP, UDP, CDP, ADP, GDP, UMP, CMP, AMP, and GMP) in human cells were used as test solutes. Column performance measurements, including electroosmotic flow (EOF), solute migration speed and retention, column efficiency, peak shape, and resolution were investigated. By analyzing solute migration speed and retention of various hydrophilic/hydrophobic solutes, the column wall effects (EOF and adsorption) can be distinguished. This analysis method can give guidance in optimizing polymer coating properties (hydrophilicity/hydrophobicity) for CE columns. By studying the performance of these columns after various surface treatments, we were able to improve the separation of ribonucleotides from real samples to within 16 minutes with high efficiency and stability (over 300 analyses) using columns first deactivated with hexamethyldisilazane, and then coated with polyethylene oxide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467560
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  • 5
    Electronic Resource
    Electronic Resource
    Polybutadiene-coated zirconia packing materials in solvating gas chromatography using carbon dioxide as mobile phase (1999)
    Springer
    Chromatographia 49 (1999), S. 431-435 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Supercritical fluid chromatography ; Solvating gas chromatography ; Polybutadiene coated zirconia ; CO2 mobile phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In this paper, practical considerations of column efficiency, separation speed, thermal stability, and column polarity of capillary columns packed with polybutadiene-coated zirconia were investigated under solvating gas chromatography (SGC) conditions using carbon dioxide as mobile phase. When compared with results obtained from conventional porous octadecyl obtained from conventional porous octadecyl bonded silica (ODS) particles, PBD-zirconia particles produced greater change in mobile phase linear velocity with pressure than conventional ODS particles under the same conditions. The maximum plate number per second (Nt) obtained with a 30 cm PBD-zirconia column was approximately 1.5 times higher than that obtained with an ODS column at 100 °C. Therefore, the PBD-zirconia phase is more suitable for fast separations than conventional ODS particles in SGC. Maximum plate numbers per meter of 76,900 and 63,300 were obtained using a 57 cm×250 μm i.d. fused silica capillary column packed with 3 μm PBD-zirconia at 50 °C and 100 °C, respectively. The PBD-zirconia phase was stable at temperatures up to 320 °C under SGC conditions using carbon dioxide as mobile phase. Polarizable aromatic compounds and low molecular weight ketones and aldehydes were eluted with symmetrical peaks from a 10 cm column packed with 3 μm PBD-zirconia. Zirconia phases with greater inertness are required for the analysis of more polar compounds by SGC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467619
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  • 6
    Electronic Resource
    Electronic Resource
    Packed capillary column supercritical fluid chromatography of fat-soluble vitamins using liquid crystal polysiloxane coated particles (1996)
    Springer
    Chromatographia 43 (1996), S. 53-58 
    Details
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Packed capillary columns ; Liquid crystalline polysiloxane ; Polymer encapsulated particles ; Vitamins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Liquid crystal polysiloxane stationary phases were prepared by coating two different polymers on deactivated porous silica particles (10 μm diameter, 80 Å pores). Deactivation of the silica particles before coating was necessary to prepare highly efficient and inert stationary phases for supercritical fluid chromatography (SFC). Fat-soluble vitamins E, A, K1, K2, D2, and D3 were separated on these columns using neat supercritical CO2 as mobile phase. The analyses were completed within 40 min at 70 °C. The results were compared to those obtained using a capillary column packed with less ordered liquid crystalm,m-cyanobiphenyl-substituted polysiloxane coated particles. Reduced shape selectivity was observed with this cyanobiphenyl phase. The response factors of vitamins A, E, K1, K2, D2, and D3 when using the flame ionization detector (FID) were determined to be very similar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272821
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  • 7
    Electronic Resource
    Electronic Resource
    End-functionalized polyethylene oxide coated silica particles for packed capillary column supercritical fluid chromatography (1996)
    Springer
    Chromatographia 43 (1996), S. 373-379 
    Details
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Packed capillary columns ; Polyethylene oxide coated phases ; Polymer encapsulated particles ; Amines and acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polyethylene oxide (PEO)-based polymers with hydroxy, methoxy, and aminopropoxy terminal groups were coated on diol functionalized and hexamethyldisilazane end-capped silica particles. Proton-donor and proton-acceptor test solutes, including carboxylic acids, hydroxy-containing compounds, arylamines, and alkylamines were used to evaluate the chromatographic performances of these polymer coated particles under SFC conditions with neat CO2 as mobile phase. It was found that the particles coated with hydroxy-terminated PEO were suitable for the separation of proton-donor compounds such as hydroxy-containing compounds and carboxylic acids, and the particles coated with aminopropoxy-terminated PEO could be used for the separation of amines. That is, the proton-accepting stationary phase is suitable for the separation of proton accepting solutes, including strong basic alkylamines (pKb≈4), using neat CO2 as mobile phase, while the protondonating stationary phase is suitable for the separation of proton-donating compounds such as carboxylic acids (pKa≈4). Hydrogen bond basicity was found to be a critical factor for the chromatography of basic amines. Low volatility acidic and basic drugs were chromatographed using the new stationary phases. The stability of the PEO coated particles was determined by measuring the loss of organic carbon under SFC conditions. It was found that approximately 18 % of the coating (average molecular weight of 15,000) was washed out of the particles by supercritical CO2 after 7 h at 350 atm and 50°C
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02271014
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  • 8
    Electronic Resource
    Electronic Resource
    Comparison of packed capillary solvating gas chromatography with supercritical fluid chromatography using carbon dioxide as mobile phase (1998)
    Springer
    Chromatographia 47 (1998), S. 673-677 
    Details
    ISSN: 1612-1112
    Keywords: Solvating gas chromatography ; Supercritical fluid chromatography ; Packed capillary columns ; Solvating power
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The efficiency (plate number per unit time) and elution power (range ofn-alkanes) of packed capillary SFC and SGC using CO2 as the mobile phase were compared. A higher plate number per unit time was obtained in SGC than in SFC using the same column under the same applied conditions. SGC is more suitable for fast separations than SFC. The solvating ability of the mobile phase, at the column exit end, decreased remarkably after the restrictor was removed. However, the elution molecular weight range in SGC can be greatly extended by increasing the column temperature.n-Alkanes with carbon numbers as high as 80 were separated under SGC conditions using a 35 cm ×250 μm i.d. column packed with 10 μm polymer-encapsulated silica particles at 200 atm, with a temperature program of 100–380°C at 10°C min−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467452
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  • 9
    Electronic Resource
    Electronic Resource
    Na+, K+-ATPase, glutathione, and hydroxyl free radicals in cadmium chloride-induced testicular toxicity in mice (1995)
    Springer
    Archives of environmental contamination and toxicology 29 (1995), S. 174-179 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Cadmium chloride (CdCl2)-induced biochemical changes were characterized in male, CD-1 mouse testes. CdCl2 inhibited the testes microsomal Na–, K–-ATPase activity in vitro and in vivo. The inhibitory range was 30–50 μm and the concentration for half maximal inhibition (IC50 value) was 90 μm over 5 min preincubation. CdCl2 (2mg/kg/day, s.c.) for 2 days significantly inhibited testes Na–, K–-ATPase (near 90% inhibition). The content of testicular GSH and the ratio of reduced glutathione (GSH)/GSSG (oxidized glutathione) decreased in CdCl2-treated groups. Using salicylate as a trapping agent and high pressure liquid chromatography with electrochemical detection (LCED), we measured the OH production in vivo. 2,5-dihydroxybenzoic acid (2,5-DHBA) and 2,3-dihydroxybenzoic acid (2,3-DHBA) as indices of hydroxyl free radical formation significantly increased after 5 days CdCl2 exposure. Pretreatment with vitamin E (20 mg/kg, s.i.d., i.m., 7d) protected CdCl2-induced increase in OH generation in testes. From this study, it was demonstrated that CdCl2 induced testicular toxicity could possibly be mediated by a significant increase in hydroxyl free radical formation and a reduction in GSH content and Na–, K–-ATPase activity. Vitamin E seems to prevent the CdCl2 induced increase in hydroxyl free radical generation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212967
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  • 10
    Electronic Resource
    Electronic Resource
    Toxicity of Aromatic Aerobic Biotransformation Products of Toluene to Hela Cells (1998)
    Springer
    Bulletin of environmental contamination and toxicology 60 (1998), S. 177-184 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001289900608
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