Preparation and characterization of magnetite (Fe3O4) nanoparticles By Sol-Gel method

The magnetite (Fe3O4) nanoparticles were successfully synthesized and annealed under vacuum at different temperature. The Fe3O4 nanoparticles prepared via sol-gel assisted method and annealed at 200-400ºC were characterized by Fourier Transformation Infrared Spectroscopy (FTIR), X-ray Diffraction spectra (XRD), Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscopy (AFM). The XRD result indicate the presence of Fe3O4 nanoparticles, and the Scherer`s Formula calculated the mean particles size in range of 2-25 nm. The FESEM result shows that the morphologies of the particles annealed at 400ºC are more spherical and partially agglomerated, while the EDS result indicates the presence of Fe3O4 by showing Fe-O group of elements. AFM analyzed the 3D and roughness of the sample; the Fe3O4 nanoparticles have a minimum diameter of 79.04 nm, which is in agreement with FESEM result. In many cases, the synthesis of Fe3O4 nanoparticles using FeCl3 and FeCl2 has not been achieved, according to some literatures, but this research was able to obtained Fe3O4 nanoparticles base on the characterization results

Charge transfer and weak bonding between molecular oxygen and graphene zigzag edges at low temperatures

Electron paramagnetic resonance (EPR) study of air-physisorbed defective carbon nano-onions evidences in favor of microwave assisted formation of weakly-bound paramagnetic complexes comprising negatively-charged O2- ions and edge carbon atoms carrying pi-electronic spins. These complexes being located on the graphene edges are stable at low temperatures but irreversibly dissociate at temperatures above 50-60 K. These EPR findings are justified by density functional theory (DFT) calculations demonstrating transfer of an electron from the zigzag edge of graphene-like material to oxygen molecule physisorbed on the graphene sheet edge. This charge transfer causes changing the spin state of the adsorbed oxygen molecule from S = 1 to S = 1/2 one. DFT calculations show significant changes of adsorption energy of oxygen molecule and robustness of the charge transfer to variations of the graphene-like substrate morphology (flat and corrugated mono- and bi-layered graphene) as well as edges passivation. The presence of H- and COOH- terminated edge carbon sites with such corrugated substrate morphology allows formation of ZE-O2- paramagnetic complexes characterized by small (<50 meV) binding energies and also explains their irreversible dissociation as revealed by EPR.Comment: 28 pages, 8 figures, 2 tables, accepted in Carbon journa

Kondo effect in CeXc_{c} (Xc_{c}=S, Se, Te) studied by electrical resistivity under high pressure

We have measured the electrical resistivity of cerium monochalcogenices, CeS, CeSe, and CeTe, under high pressures up to 8 GPa. Pressure dependences of the antiferromagnetic ordering temperature $T_{N}$, crystal field splitting, and the $\ln T$ anomaly of the Kondo effect have been studied to cover the whole region from the magnetic ordering regime at low pressure to the Fermi liquid regime at high pressure. $T_{N}$ initially increases with increasing pressure, and starts to decrease at high pressure as expected from the Doniach's diagram. Simultaneously, the $\ln T$ behavior in the resistivity is enhanced, indicating the enhancement of the Kondo effect by pressure. It is also characteristic in CeX$_{c}$ that the crystal field splitting rapidly decreases at a common rate of $-12.2$ K/GPa. This leads to the increase in the degeneracy of the $f$ state and further enhancement of the Kondo effect. It is shown that the pressure dependent degeneracy of the $f$ state is a key factor to understand the pressure dependence of $T_{N}$, Kondo effect, magnetoresistance, and the peak structure in the temperature dependence of resistivity.Comment: 9 pages, 5 figures, accepted for publication in J. Phys. Soc. Jp

Metacarpophalangeal pattern profile analysis of a sample drawn from a North Wales population

This is tha author's PDF version of an article published in Annals of human biology© 2001. The definitive version is available at http://www.tandf.co.uk/journalsSexual dimorphism and population differences were investigated using metacarpophalangeal pattern profile (MCPP) analysis. Although it is an anthropmetric technique, MCPP analysis is more frequently used in genetic syndrome analysis and has been under-used in the study of human groups. The present analysis used a series of hand radiographics from Gwynedd, North Wales, to make comparisons, first, between the sexes within the sample and then with previously reported data from Japan. The Welsh sexes showed MCPP analyses that indicated size and shape differences but certain similarities in shape were also evident. Differences with the Japanese data were more marked. MCPP anlysis is a potentially useful anthropmetric technique but requires further statistical development

Hysterosalpingographic findings in infertile women: A seven year review

Objectives: To review the hysterosalpingographic (HSG) findings in women investigated for infertility in a tertiary center in north eastern Nigeria.Materials and Methods: A retrospective review of HSG films of 272 women investigated for infertility between January 2000 and December 2006 were reviewed.Results: One hundred and thirty (47.8%) were investigated for primary infertility, while 142 (52.2%) were investigated for secondary infertility. Most of the women investigated for infertility by HSG had abnormal findings 192(70.6%). The most common pathology revealed among the infertile women was tuboperitoneal factor in 196 (72.1%) followed by uterine synechia in 35(12.9%). Seventeen (6.3%) had bilateral tubal block and 5 (1.8%) had bicornuate uterus.Conclusion: HSG is helpful in the investigation of infertile women

Umbilical cord infection prevention practices among rural women attending immunization clinic in kumbotso, Kano state, Nigeria

Umbilical cord infections are more prevalent in developing countries because of the high rates of unhygienic cord care practices. Objectives: This study was undertaken to explore the various practices related to umbilical cord care among rural community women attending an immunization clinic in Kumbotso, Kano State, Nigeria. Method: A descriptive cross-sectional study design was used for the study. This study was carried out in immunization clinic at Kumbotso CHC of Kumbotso Local Government Area (LGA), Kano state Nigeria. Sample size was 265. Data was collected with interviewer administered semi-structured questionnaire and analyzed using Statistical Package for Social Science (SPSS) version 20 software. The result obtained was presented in the form of tables. Results: Majority, 200 (75.5%) of respondents' hands were gloved. In 126 (47.5%) of respondents, new razor blades were used, in 117 (44.2%) of respondents' scissors was used and the remaining 22 (8.3%) of respondents used razor blade or knife to cut the umbilical cord. Up to 159 (60%) of respondents applied mentholated spirit. One hundred and sixty-nine (63.8%) of respondents were informed of safe umbilical cord practices by health workers. Cord infection rate occurred in 53 (20.1%) babies. Conclusion: Cord infection prevention and control practices were high in this community with a relatively low cord infection rate. Even though Chlorhexidine was not used, health workers should emphasize and as well recommend its use in cord care. Community-based study is recommended to generate data about cord infections and practices inside the community

Persistent Currents in the Presence of a Transport Current

We have considered a system of a metallic ring coupled to two electron reservoirs. We show that in the presence of a transport current, the persistent current can flow in a ring, even in the absence of magnetic field. This is purely a quantum effect and is related to the current magnification in the loop. These persistent currents can be observed if one tunes the Fermi energy near the antiresonances of the total transmission coefficient or the two port conductance.Comment: To appear in Phys. Rev. B. Three figures available on reques