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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 3659-3666 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polyimide was irradiated with a XeCl excimer laser (308 nm) and the ablated area and its surrounding were studied using transmission electron microscopy (TEM) and confocal Raman microscopy. Ring-like structures surrounding the ablated area were detected at all fluences. At fluences lower than 250 mJ/cm−2 the formation of conical structures was observed within the irradiated area. The width of the rings increases with fluence and only slightly with the number of pulses. The rings consist mainly of polycrystalline carbon with a relatively high bond angle disorder, with thickness decreasing radially from the crater edge. The thickness of the deposited carbon was determined from TEM analysis and calculated from the intensity ratios of Raman bands assigned to carbon and polyimide using a two layer model. Comparing the two results an estimate of the absorption coefficient of the deposited carbon could be obtained. On top of the cone structures carbon was detected with a higher degree of crystallinity and lower bond angle disorder as compared to the material deposited outside the crater. With energy dispersive x-ray analysis, calcium could be detected on top of the cones. Therefore, it can be assumed that the Ca impurities are causing the cone structures. The higher crystallinity of the carbon inside the irradiated area is probably due to a tempering-like process on top of the Ca compound which is heated upon laser irradiation or to a mixture of growth mechanisms similar to the ones suggested for the formation of carbon nanotubes on metal particles and carbon nanohorns without metal catalysis. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 2812-2817 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Carbon nitride films with β-C3N4 crystals were grown on Si(100) substrates using reactive sputtering. The deposition was achieved using a graphite target in an argon/nitrogen plasma. Different nitrogen (N2) fractions and substrate biases were used while the other parameters remained fixed. Atomic force microscopy (AFM) was used to measure the surface roughness and surface morphology. X-ray photoelectron spectroscopy (XPS) and ellipsometry measurements were carried out to analyze nitrogen content, chemical bonding state, and optical properties. AFM measurement indicated the surface roughness ranged from 0.2 to 2.5 nm. From XPS data, maximum N/C ratio of 0.5 was achieved in the films. The XPS C 1s spectrum for C(Single Bond)N bond is at 287.32 eV while the N 1s spectrum has a corresponding peak of C(Single Bond)N bond at 398.46. At N2 fraction from 0.6–0.8 and bias from −120 to −200 V, high sp3/sp2 ratio and more β-C3N4 crystals were obtained. Consequently, the films grown at these conditions had high optical band gap. The optical band gap ranged from 1.35 to 2.5 eV. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 4099-4104 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Carbon nitride films with β-C3N4 crystals of 200 nm grain size were grown on Si (100) substrates using magnetron sputtering. Reactive deposition was achieved using a graphite target in an argon/nitrogen plasma at room temperature. These films were characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy. Micro level β-C3N4 crystal grains were observed with TEM. According to calculations from electron diffraction pattern, these crystalline structures were in a good agreement with hypothetical b-C3N4 structure. AFM measurement also indicated the grain size was around 200 nm and the carbon nitride films had low surface roughness. From XPS data, maximum N/C ratio of 0.5 was achieved in the films. XPS spectra of the films typically showed three peaks in the C 1s core level spectrum (centered at 284.6, 285.9, and 287.2 eV) and two peaks in the N 1s core level spectrum (centered at 398.7 and 400.2 eV). This indicates that there are two types of C–N bonds; N is bonded to sp2- or sp3-coordinated C atoms in the as-deposited films. FTIR spectra showed three absorption bands in the range of 1000–3000 cm−1. The absorption band around 2367 cm−1 can be attributed to C(Triple Bond)N nitrile bond. The absorption bands around 1559 and 1201 cm−1 demonstrate the existence of C(Double Bond)N (sp2) and C–N (sp3) bonds. Analysis of Raman spectrum further demonstrated the coexistence of sp, sp2, and sp3 bonds. All of XPS, FTIR, and Raman measurements showed the presence of fourfold coordinated β-C3N4 crystals in the films, which is in good agreement with TEM and electron diffraction results. © 2001 American Institute of Physics.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Community dentistry and oral epidemiology 31 (2003), S. 0 
    ISSN: 1600-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract  Objectives: Use of fluoridated milk has been shown to be a safe and effective method to prevent caries in permanent teeth in children. However, studies on its effectiveness on caries prevention in the primary teeth are scarce. The purpose of the present study was to evaluate the effect of milk fluoridation on caries development in young Chinese children.Methods: This was a community-based demonstration study carried out in Beijing, China. All children in three selected kindergartens were invited to participate. Each participant consumed 200 ml of fluoridated milk (concentration 2.5 mg F− per litre) per day from Monday to Friday in the kindergarten, and was given two packs of fluoridated milk (250 ml) for consumption at home on Saturday and Sunday every week. Children from a similar background, but without access to fluoridated milk, attending two other kindergartens, were used as the control.Results: There were 534 children (mean age 54 ± 4 months) and 305 children (mean age 53 ± 4 months) in the test and control groups, respectively, at baseline. After 21 months, 417 and 247 children in the test and control groups, respectively, remained in the study. There was no statistically significant difference in the baseline mean dmft scores between the two groups (3.2 vs. 3.5, P = 0.312). After 21 months, the mean net caries increment was 0.4 dmft for the test group and 1.3 dmft for the control group (t-test, P 〈 0.001).Conclusion: The consumption of fluoridated milk by the kindergarten children in Beijing was an effective measure in preventing caries in the primary teeth.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Haemophilia 10 (2004), S. 0 
    ISSN: 1365-2516
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary.  We reported a 51-year-old man who developed a severe haematuria with a prolonged prothrombin time (PT) and activated partial thromboplastin time (aPTT). Laboratory evaluation revealed the presence of specific factor V inhibitors. No underlying diseases and associated conditions have been identified. The patient improved after immunosuppressive therapy. However, the FV level remained low, indicating incomplete inhibitor eradication. The clinical course of our patient was consistent with the observations by others that FV inhibitor can be persistent for months or years.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The initial desertification in the Asian interior is thought to be one of the most prominent climate changes in the Northern Hemisphere during the Cenozoic era. But the dating of this transition is uncertain, partly because desert sediments are usually scattered, discontinuous and difficult to ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 471-472 (Dec. 2004), p. 390-395 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The effect of died-pressed binders, such as polyvinyl alcohol (PVA), butyl sodium rubber (BSR) and paraffin wax (PW), on green strength, green density, dimensional stability, residue, sintered compact density and mechanical properties of Ti(C,N)-based cermet was investigated. It was found that the types of the binder had a significant impact on the characteristics of the green compact.PVA improved dimensional stability of the green compact due to interaction between binder and particle. The glass transition temperature (Tg) of PVA influenced the forming behavior of Ti(C,N)-based cermet powders during died-pressed processing. Some residual moisture was needed to obtain high green strength. PVA had a gradual burnout with a low char residue in nitrogen. Compared with PVA, the influence of binders BSR and PW was also presented and discussed
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 17 (2000), S. 612-618 
    ISSN: 1573-904X
    Keywords: membrane permeability ; surface pressure ; liposome ; surface tension ; phospholipid monolayer ; bile salts ; nonylphenoxy polyoxyethylene ; model membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To gain some mechanistic understanding of surfactant-inducedmembrane permeabilization and identify a surfactant physicalproperty that can be used as a predictor for intestinal membranepermeability enhancement. Methods. The maximum surface pressures (πCMC) of series of anionicand non-ionic surfactants as indicators of surface activity were determinedusing a bubble surface tensiometer, and related to in vivointestinal membrane permeability and acute damage data of the samesurfactants from a previous work. Phospholipid bilayers with constantsurface pressures and monolayers with different surface pressures wereused as model membranes to systematically study membrane permeabilityenhancement and membrane penetration of surfactants at differentconcentrations. Results. Surfactants that did not permeabilize or acutely damage theintestinal wall generally exhibited a πCMC 〈 25 dyne/cm. Permeabilityenhancement and acute damage increased as πCMC increased beyond25 dyne/cm. This critical threshold value at around 25 dynes/cm wasalso observed with in vitro experiments using phospholipid vesiclesand monolayers. Data support the hypothesis that the thresholdphenomenon originates from the interfacial tension at the membrane/waterinterface, which controls the surface adsorption process of surfactantmolecules onto the membrane. Conclusions. For a surfactant to permeabilize and acutely damage theintestinal wall, it must exhibit a surface pressure of greater than 25dynes/cm. This threshold value is related to an intrinsic property,surface pressure, of the phospholipid membranes. Since the surfactantsurface pressure is a property of the surfactant monomer, partition ofthe surfactant monomer, not the micelle, into the membrane is anobligate step in membrane permeabilization. Above the surfactantcritical micelle concentration, CMC, micelles may act as a depot tocontinuously replace aqueous surfactant monomers taken up by the membrane.For some surfactants above CMC, sufficient number of monomers canpartition into the membrane to cause solubilization of membrane lipidsin surfactant micelles.
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  • 9
    ISSN: 1573-904X
    Keywords: scopolamine ; motion sickness ; nasal absorption ; pH effect ; dose effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The present study was conducted to evaluate theeffects of formulation pH and dose on nasal absorption of scopolaminehydrobromide, the single most effective drug available for the prevention ofnausea and vomiting induced by motion sickness. Methods. Human subjects received scopolamine nasally at adose of 0.2 mg/0.05 mL or 0.4 mg/0.10 mL, blood samples were collected atdifferent time points, and plasma scopolamine concentrations were determinedby LC-MS/MS. Results. Following administration of a 0.2 mg dose, theaverage Cmax values were found to be 262 ± 118, 419± 161, and 488 ± 331 pg/mL for pH 4.0, 7.0, and 9.0formulations, respectively. At the 0.4 mg dose the average Cmaxvalues were found to be 503 ± 199, 933 ± 449, and 1,308± 473 pg/mL for pH 4.0, 7.0, and 9.0 formulations, respectively. At a0.2 mg dose, the AUC values were found to be 23,208 ± 6,824, 29,145± 9,225, and 25,721 ± 5,294 pg.min/mL for formulation pH 4.0,7.0, and 9.0, respectively. At a 0.4 mg dose, the average AUC value wasfound to be high for pH 9.0 formulation (70,740 ± 29,381 pg.min/mL)as compared to those of pH 4.0 (59,573 ± 13,700 pg.min/mL) and pH 7.0(55,298 ± 17,305 pg.min/mL) formulations. Both the Cmaxand AUC values were almost doubled with doubling the dose. On the otherhand, the average Tmax values decreased linearly with a decreasein formulation pH at both doses. For example, at a 0.4 mg dose, the averageTmax values were 26.7 ± 5.8, 15.0 ± 10.0, and 8.8± 2.5 minutes at formulation pH 4.0, 7.0, and 9.0, respectively. Conclusions. Nasal absorption of scopolamine hydrobromidein human subjects increased substantially with increases in formulation pHand dose.
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