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  • 1
    Electronic Resource
    Electronic Resource
    Change in magnetic state of Fe+silica gel nanocomposites due to low temperature treatment in ammonia : 35th annual conference on magnetism and magnetic materials San Diego, California (USA) 29 Oct−Nov 1990 (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5144-5146 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Homogeneous gelled composites of iron and silica containing 11–40 wt. % Fe were prepared by room temperature polymerization of aqueous solutions of ferric nitrate, tetraethoxysilane, and ethanol (with an HF catalyst). Previous electron microscopy, x-ray diffraction, and Mössbauer effect data showed these bulk materials are comprised of nanometer-sized regions of iron compounds embedded in a silica gel matrix. They were also all paramagnetic below 300 K. Here the effect on the magnetic state of these nanocomposites following a low temperature (T〈400 °C) treatment in 1 atm of ammonia (after a prior anneal in 1 atm of hydrogen) is presented, along with the dependence on the H2 pretreatment. In all cases the room temperature Mössbauer spectra for the material in the NH3-treated and H2-pretreated conditions were similar. However, when treated in H2 at 770 °C (2 h) the Mössbauer spectra also contained a significant component having a large isomer shift (∼1.3 mm/s) and quadrupole splitting (∼3.2 mm/s). This material was also slightly ferromagnetic at all temperatures below 300 K. For materials pretreated in hydrogen below 400 °C, a threefold enhancement in the magnetic susceptibility was measured following treatment in ammonia. In addition, both the field and temperature dependence of the susceptibility indicated the presence of spin-glass behavior at 10 K for NH3-treated samples containing up to 40% Fe. At room temperature, these latter ammonia-treated nanocomposites were either superparamagnetic (Fe contents, CFe, up to 25%) or ferromagnetic (CFe(approximately-greater-than)25%).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348104
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  • 2
    Electronic Resource
    Electronic Resource
    Enhanced magnetocaloric effect in Gd3Ga5−xFexO12 : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6946-6948 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The working refrigerant material in the majority of magnetic refrigerators has been Gd3Ga5O12 (GGG) which has an upper temperature limit near 15 K. In this paper we report on the field-induced adiabatic magnetic entropy change, ΔSm(H,T), of a series of iron-substituted gadolinium garnets (GGIG) Gd3Ga5−xFexO12 which have the potential to increase the working temperature range or to reduce the field requirements of cryogenic magnetic refrigeration. Depending on Fe concentration, x, the entropy change of these materials at applied fields of 0.9 and 5.0 T is much greater than that of GGG, especially at temperatures above 15 K. At low Fe concentrations, the results are consistent with formation of magnetically ordered clusters of spins at low temperatures. Room temperature electron paramagnetic resonance measurements show that Fe3+ ions mediate exchange interactions which are responsible for clustering at low temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352443
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  • 3
    Electronic Resource
    Electronic Resource
    Fe Mössbauer effect in YxPr1−xBa2(Cu0.98Fe0.02)3O7 (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 5029-5031 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: 57Fe Mössbauer effect and magnetic-susceptibility measurements were performed on Y0.2Pr0.8Ba2(Cu0.98Fe0.02)3O7−δ and Y0.8Pr0.2Ba2(Cu0.98Fe0.02)3O7−δ, where δ≈0. The insulating 80% Pr compound showed susceptibility anomalies and a large hyperfine field distribution at low temperatures in addition to a hyperfine field spectrum for Fe on the Cu(2) sites. The superconducting 20% Pr compound displayed none of these effects at any temperature. After examining the alternatives, it is postulated that magnetic ordering of the Pr ions and an enhanced rare-earth transition-metal interaction due to f-electron admixture is responsible for these observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344713
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  • 4
    Electronic Resource
    Electronic Resource
    Iron magnetic moments in iron/silica gel nanocomposites (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4490-4492 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Homogeneous gelled composites of iron and silica containing 11–40 wt. % Fe have been prepared by low-temperature polymerization of aqueous solutions of ferric nitrate, tetraethoxysilane, and ethanol (with an HF catalyst). X-ray diffraction, electron microscopy, Mössbauer effect, and magnetization measurements have been used to show that these bulk materials are paramagnetic composites at room temperature and remain in that state to 10 K. In this condition the Fe is present in nanometer-sized regions and exists in ionic form (both Fe3+ and Fe2+ ). It possesses a large magnetic moment which decreases linearly from 3.9 μB/ Fe atom to 2.8 μB /Fe atom as the Fe content increased from 11% to 40%. For this composition increase, a negative Curie-Weiss temperature was found which increased in magnitude linearly from −13 to −46 K. It is suggested that many of the iron atoms in the as-cured nanocomposites interact antiferromagnetically, and that the magnitude of the effect increases with the Fe concentration. After treatment in hydrogen, the state of the Fe changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344891
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  • 5
    Electronic Resource
    Electronic Resource
    A PCR study on the coexistence of herpes simplex virus, cytomegalovirus and human papillomavirus DNAs in cervical neoplasia (1996)
    Suite 500, 5th Floor, 238 Main Street, Cambridge, Massachusetts 02142, USA : Blackwell Science Inc.
    International journal of gynecological cancer 6 (1996), S. 0 
    Details
    ISSN: 1525-1438
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: There is strong epidemiological and biological evidence that the development of squamous cell carcinoma of the cervix is a multistep process in which human papillomaviruses (HPVs) play a crucial but not total role and where the synergistic effect of herpes simplex virus (HSV) and human cytomegalovirus (HCMV) has been suggested. The presence of HPV, HSV and HCMV deoxyribonucleic acids (DNAs) was assessed by a polymerase chain reaction (PCR) in cervical biopsies obtained from 41 women with cervical neoplasia (21 high-grade cervical intra-epithelial neoplasia (CIN) and 20 squamous cell cancers) and 33 controls. Human papillomavirus 16 DNA was significantly more common in high-grade CIN (57%) and cancer (50%) than in normal cervix (9%). Herpes simplex virus and HCMV DNAs were present in 12% and 21% of normal cervices, 19% and 24% of high-grade CIN, and 25% and 25% of cancers, respectively. After adjustment for patients’ age, coinfection associating high-risk HPVs (HPV 16 and/or HPV 18) and herpes viruses (HCMV and/or HSV) were observed in cervical neoplasia (odds ratio (OR) = 19.11; 95% confidence interval (CI): 2.14–170.36). Conversely, the OR for infection by HPV 16 and/or HPV 18 alone did not reach statistical significance (OR = 7.22; 95% CI: 0.85–61.16). Moreover infection by HCMV and/or HSV alone (OR = 0.89; 95% CI: 0.33–2.24) was not associated with cervical neoplasia. Our results support the role of HSV and HCMV as cofactors of HPV 16 and HPV 18 in cervical neoplasia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1525-1438.1996.06050389.x
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  • 6
    Electronic Resource
    Electronic Resource
    Xylyl Methyl Carbinols (1941)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 63 (1941), S. 1478-1479 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01850a511
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  • 7
    Electronic Resource
    Electronic Resource
    The Reaction of Thiuram Disulfide with Halomethyl Ketones (1947)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 69 (1947), S. 2069-2070 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01200a516
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  • 8
    Electronic Resource
    Electronic Resource
    Magnetic properties of colloidal silica: Potassium silicate gel/iron nanocomposites : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6840-6842 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Homogeneous composites of Fe and silica containing 5–40 wt % Fe have been prepared by infiltration of ferric nitrate solution into a colloidal silica: potassium silicate gel at room temperature. Previous electron microscopy, small angle neutron scattering, and nitrogen sorption (BET) measurements on such gels have shown they are comprised of an interconnected silica matrix, having pores ranging from 2–800 nm in size. Mössbauer effect and magnetization data show the Fe is in a paramagnetic environment with weak antiferromagnetic interactions. Curie–Weiss analysis indicated negative intercepts of the temperature axis for all the samples and that the magnetic moment per Fe atom (μFe) decreased as the Fe content increased at a rate of ∼0.0058 μB/% Fe. For most of the samples μFe≈2.1 μB. By contrast, in silica gel/Fe nanocomposites formed by the polymerization of an aqueous solution of tetraethoxysilane and iron nitrate, the Fe possessed magnetic moments varying from 3.9 to 2.9 μB. It is suggested that the difference is a result of the different pore structures of the gels, and not due to the different methods (e.g., postmatrix infiltration as compared to premixing prior to matrix polymerization) used to introduce the Fe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356802
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  • 9
    Electronic Resource
    Electronic Resource
    Increased prevalence of herpes viruses in high grade CIN and carcinoma of the cervix: the potential for synergistic effect (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the European Academy of Dermatology and Venereology 4 (1995), S. 0 
    Details
    ISSN: 1468-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective To assess the prevalence of human papillomavirus (HPV) type 16 and 18, herpes simplex virus (HSV) and human cytomegalovirus (HCMV) in cervical biopsies in order to evaluate their relationship in cervical intraepithelial neoplasia (CIN) and cancer.Setting Colposcopy clinic; Service de Gynécologic-Obstétrique I, Hôpital de Hautepierre. Hôpitaux Universities de Strasbourg and Laboratoire Commun ULP/Synthélabo et U74 INSERM. Institut de Virologie dc la Faculté de Medecine de Strasbourg, France.Subjects Forty-two women with low grade and high grade CIN, twenty women with cervical squamous cancer and twenty-two women with normal cervix assessed by cytological, colposcopical and histological analysis.Methods Viral DNA was detected by PCR technique in colposcopically directed biopsies.Results The prevalence of HPV16 and/or HPV18 with HSV and/or HCMV was significantly higher in cancers (25%) or high grade CIN (29%) than in normal cervices (0%). On the contrary, when only HPV DNA was found, there was no significant difference between cancers (3O%). high grade CIN (29%) and normal cervices (9%).Conclusions The results support the hypothesis of a role of herpes viruses (HSV and HCMV) as cofactors in cervical carcinogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1468-3083.1995.tb00298.x
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  • 10
    Electronic Resource
    Electronic Resource
    An extended Langmuir model for adsorption of gas mixtures on heterogeneous surfaces (1990)
    s.l. : American Chemical Society
    Langmuir 6 (1990), S. 660-664 
    Details
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/la00093a022
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