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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of the barrier function in a reconstituted human epidermis cultivated in chemically defined medium (2002)
    Oxford, UK : Blackwell Science, Ltd
    International journal of cosmetic science 24 (2002), S. 0 
    Details
    ISSN: 1468-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The aim of the study was to characterize and assess the maturation process of the barrier function in a reconstituted human epidermis (REp) cultivated in a chemically defined medium. For this purpose histo-morphological analysis, percutaneous absorption studies and non-invasive measurements were performed. In order to understand the time course of the barrier development, REp cultivated from the same pool of normal human keratinocytes were harvested and measured after several increasing periods of exposure at the air–liquid interface. From these results we concluded that a maturation period of at least 16 days at the air–liquid interface was required for an optimal barrier function development of REp. At this time point, the permeability of the skin cultures for caffeine (CAF) was 20–25-fold higher than that of normal human skin (NHS) biopsies. Non-invasive measurements of skin water content, transepidermal water loss (TEWL) and pH were achieved after the same period of time. Results showed that the stratum corneum (SC) of REp was slightly more hydrated than that of ex vivo and in vivo, human skin. TEWL was slightly higher through REp than through NHS, and the pH of the REp models was very close to that of in vivo, normal human skin. In the latter part, assuming that this type of model could be routinely used, we quantified over a 1-year period the barrier function variability of this skin culture model between batches. The satisfactory results obtained with a 20% coefficient of variation indicated that this REp model has a consistent and reproducible barrier function. This leads us to suggest that the skin model might be considered an alternative membrane to normal human skin for permeation screening tests.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0412-5463.2001.00112.x
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  • 2
    Electronic Resource
    Electronic Resource
    Balistic magnetoresistance in nanocontacts electrochemically grown between macro- and microscopic ferromagnetic electrodes (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1785-1787 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Our results prove the local origin of magnetoresistance in electrochemically deposited Ni nanocontacts. Experiments have been done using a complex setup for both in situ growth and ballistic magnetoresistance (BMR) measurements. Nanocontacts have been grown between two macroscopic Ni wires. In situ experiments with variation of the nanocontact diameter from 3 to 20 nm have been done using the same pair of wires. BMR values from 0.5% to 100% have been observed but no correlation of BMR value with the sample resistance, i.e., with the nanocontact cross section, has been found. These results show that the BMR in the nanometric size contact is determined by local geometrical and magnetic structures near the nanocontact rather than by the contact cross section itself. The hypothesis of existence of the intrinsic nonmagnetic dead layer in the ferromagnetic nanocontact is proposed to account for the BMR properties of the nanometric size contacts. Additionally, we report a BMR value of 200% in a Ni nanocontact (5 nm diameter) electrochemically grown between two nonmagnetic macroscopic gold wires. An external magnetic field has been used during the electrochemical deposition to fix the easy magnetic axis of the deposited Ni layer. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1459108
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  • 3
    Electronic Resource
    Electronic Resource
    Ballistic magnetoresistance in a nanocontact between a Ni cluster and a magnetic thin film (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 2946-2948 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present measurements of ballistic magnetoresistance in nanocontacts grown by electrodeposition of Ni microclusters on magnetic thin films covered by aluminum oxide layers, using a technique proposed by Schad et al. [D. Allen, R. Schad, G. Zangari, I. Zana, D. Yang, M. C. Tondra, and D. Wang, J. Vac. Sci. Technol. A. 18, 1830 (2000); Appl. Phys. Lett. 76, 407 (2000); D. Allen, R. Schad, G. Zangari, I. Zana, D. Yang, M. C. Tondra, D. Wang, and D. Reed, J. Appl. Phys. 89, 6662 (2001)]. The measurements are made on single Ni clusters in contact with a Ni and Co thin film. We measure the magnetoresistance and observe the relaxation of the magnetization and electrical resistance as a function of time. The clusters are electrodeposited under several different experimental conditions. Some are deposited randomly on an unpatterned film and some through various patterned photoresists that control the location at which the cluster is grown. The typical contact size is estimated from the electrical resistance to be 10–30 nm. Ballistic magnetoresistance values up to 14% are obtained in these first experiments. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1413734
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  • 4
    Electronic Resource
    Electronic Resource
    Displacement of domain walls under a nanocontact current: Mechanism for magnetoresistance asymmetric switching (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 2222-2224 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We study the action of a magnetic field induced by nanocontact current pulses on the domain walls in thin magnetic films. We show that the pulses of a certain current direction shift the wall to the contact. Such an effect of attraction of the wall to the nanocontact does not depend on the initial position of the wall relative to the contact and results in an increase of nanocontact magnetoresistance. The opposite pulses repel this wall from the contact, i.e., the field action depends on the current direction. Our calculations explain experimental data relating to magnetoresistance devices. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1403315
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  • 5
    Electronic Resource
    Electronic Resource
    Ballistic magnetoresistance in transition-metal nanocontacts: The case of iron (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 2586-2587 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This letter shows that the ballistic magnetoresistance of Fe at room temperature and low magnetic fields is ten times smaller than for Ni and Co. The results are well explained by theory that provides a global understanding for 3d transition metals because, for Fe, the ratio of majority to minority spins at Fermi level is much smaller than for Ni and Co. The data indicate that conduction is carried out by majority d electrons in the case of Fe, in contrast to what happens for Ni and Co. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126416
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  • 6
    Electronic Resource
    Electronic Resource
    Zero permittivity materials: Band gaps at the visible (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1120-1122 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We theoretically discuss the possibility of having materials with zero effective permittivity that would create band gaps in a wide range of frequencies up to the visible. The physical realization of these materials is also discussed in terms of embedding metallic nanoparticles and nanowires in a dielectric medium. In the limit of long wavelengths, these composites will behave like a homogeneous medium with zero permittivity that will completely reflect electromagnetic waves. We present transmittivity calculations by using finite-difference time domain for periodic structures that proves the concept and shows the validity of the long wavelength approximation. The striking result is that the cutoff frequency ωc is determined by the lattice parameter of the composite. By properly choosing the lattice constant of the composite and permittivity of metal and dielectric constituents, we can have full band gaps at any frequency range but especially in the visible. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1449529
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  • 7
    Electronic Resource
    Electronic Resource
    Ballistic magnetoresistance in a magnetic nanometer sized contact: An effective gate for spintronics (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 4550-4552 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present experimental results of unprecedented large magnetoresistance obtained in stable electrodeposited Ni–Ni nanocontacts 10–30 nm in diameter. The contacts exhibit magnetoresistance of up to 700% at room temperature and low applied fields and, therefore, act as very effective spin filters. These large values of the magnetoresistance are attributed to spin ballistic transport through a magnetic "dead layer" at the contact of width of about 1 nm or smaller. Nanometer sized, high sensitive magnetoresistive sensors could become key elements for magnetic storage in the terabit/in.2 range and in high density magnetic random access memories. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1427152
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  • 8
    Electronic Resource
    Electronic Resource
    Conducting ballistic magnetoresistance and tunneling magnetoresistance: Pinholes and tunnel barriers (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 1351-1353 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This letter shows that conducting ballistic and tunneling magnetoresistances have identical physical treatments and, therefore, it is not possible to distinguish whether an experiment is measuring, in oxide barriers, electron conduction through pinholes or tunneling because both types of conduction are governed by the same physics. Currents in both cases are calculated by matching wave functions at the electrodes (both are ballistic). Therefore, pinholes or small ballistic nanocontacts in the tunnel barrier allow conducting ballistic electrons that account for most of the current. We also show that, in the case of nonsuperconducting materials, e.g., magnetic materials, current–voltage characteristics are not suitable to distinguish one process from the other. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1290271
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  • 9
    Electronic Resource
    Electronic Resource
    Proton pump inhibitor, clarithromycin and either amoxycillin or nitroimidazole: a meta-analysis of eradication of Helicobacter pylori (2000)
    Oxford UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 14 (2000), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To perform a meta-analysis of studies comparing twice daily, one-week triple therapy with a proton pump inhibitor, clarithromycin (C) and amoxycillin (A) (PCA) vs. those using proton pump inhibitor, clarithromycin and a nitroimidazole (N) (PCN) for H. pylori eradication.〈section xml:id="abs1-2"〉〈title type="main"〉Review methods:Selection criteria: Comparative randomized trials of PCA vs. PCN were included. Data sources: PubMed database and abstracts from congresses until September 1999. Statistics: Meta-analysis was performed combining the Odds Ratios (OR) of the individual studies in a global OR (Peto method) both on an intention-to-treat (ITT) and on a per protocol (PP) basis.〈section xml:id="abs1-3"〉〈title type="main"〉Results:Twenty-two studies fulfilled the inclusion criteria. Eighteen studies reported ITT and 20 PP analysis. Mean H. pylori eradication rates were 81% (95% CI: 79–83%) ITT, and 84% (82–86%) PP with PCA, and 81% (78–83%) ITT and 84% (82–86%) PP with PCN; the odds ratio for the effect of PCA vs. PCN was 1 (0.83–1.22) on an ITT, and 0.98 (0.8–1.2) on a PP basis. Subanalysis showed that mean H. pylori eradication efficacy with PC(250 b.d.)A was 81% (78–85%) ITT, vs. 86% (83–89%) with PC(250 b.d.)N. The odds ratio for this comparison was 0.68 (0.48–0.98). Finally, when comparing PC(500 b.d.)A against PC(250 b.d.)N ITT cure rates were 77% (74–80%), and 75% (72–78%) with an odds ratio of 1.18 (0.93–1.5).〈section xml:id="abs1-4"〉〈title type="main"〉Conclusion:Overall, one-week combination regimens of PCA and PCN present similar H. pylori eradication efficacy. Nevertheless, the PCN regimen obtains significantly better results when using low doses of C (250 mg b.d.).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2036.2000.00844.x
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  • 10
    Electronic Resource
    Electronic Resource
    Modified seven-day, quadruple therapy as a first line Helicobacter pylori treatment (2001)
    Oxford UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 15 (2001), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Cure rates of 7-day triple therapy seem to be decreasing. Quadruple therapies may be an alternative, although their complex administration makes patient acceptance difficult.〈section xml:id="abs1-2"〉〈title type="main"〉Objective:To test the usefulness of a thrice a day, quadruple therapy to cure Helicobacter pylori infection.〈section xml:id="abs1-3"〉〈title type="main"〉Patients and methods:A total of 122 consecutive patients with peptic ulcer and Helicobacter pylori infection were treated with omeprazole 20 mg b.d., tetracycline chlorhydrate 500 mg t.d.s., metronidazole 500 mg t.d.s., and bismuth subcitrate 120 mg t.d.s. administered with meals for 7 days. Cure was tested by either endoscopy or breath test after 2 months, and by urea breath test 6 months after therapy.〈section xml:id="abs1-4"〉〈title type="main"〉Results:Seven patients were lost to follow-up. Of the remaining 115, 110 were cured at the first control, giving an intention-to-treat cure rate of 90.2% (95% CI: 83–95%) and a per protocol cure rate of 95.7% (95% CI: 90–98%). One hundred three patients returned for a 6-month breath test; all but one were cured. Side-effects were minimal or minor in 47 patients (40.8%) and moderate in four (3.4%). Compliance was good, 95% of patients taking more than 90% of the pills. Six (5%) patients stopped treatment after 1, 2, 4 (two patients) and 6 (two patients) days.〈section xml:id="abs1-5"〉〈title type="main"〉Conclusion:Thrice a day quadruple therapy shows excellent cure rates, far above 90%, is well-tolerated and compliance is easy. Head-to-head comparison with triple therapies as first line Helicobacter pylori treatment seems warranted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2036.2001.00984.x
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