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► Cu1−xCdxFe2O4 mixed metal oxides. ► Sol–gel auto-combustion method. ► Cubic spinel symmetry. ► Semiconducting nature. ► Ferrimagnetic material.
Cu1−xCdxFe2O4 (x=0.0, 0.25, 0.50, ...0.75, 1.0) ferrite nanoparticles were synthesized by sol–gel auto-combustion method. The thermal decomposition process was investigated by Differential Thermal Analysis (DTA) and Thermo Gravimetric Analysis (TGA) technique. The phase composition of the copper cadmium ferrite samples were characterized by powder X-ray diffraction analyses (XRD). All the samples reveal formation of cubic spinel symmetry. The surface morphology of Cu1−xCdxFe2O4 ferrite powder was investigated by scanning electron microscope (SEM), while elemental compositions of sample were studied by energy dispersive X-ray analysis (EDAX). The DC conductivity studies of the samples reveal their semiconducting nature. Vibrating sample magnetometer (VSM) studies showed that, all the samples are ferrimagnetic in nature at room temperature.
▶ Nanocrystalline cubic spinel ZnTiFeO
4 was successfully synthesized by the sol–gel autocombustion route. ▶ Particle size of this sample was estimated to be ∼30
nm. ▶ Magnetic study shows that ...ZnTiFeO
4 is strongly ferrimagnetic in nature.
Nanocrystalline Ti-substituted zinc ferrite was synthesized by sol–gel autocombustion route. Structural characterization of the sample was carried out by the X-ray diffraction technique which confirms that it is a single phase cubic ferrite. The FTIR spectra revealed two absorption bands which are attributed to the fundamental vibrational modes of tetrahedral and octahedral complexes of the unit cell. The IR bands due to tetrahedral complexes are found to shift slightly towards higher frequency side where as that due to octahedral complexes are found to shift towards lower frequency side. The particle size of the Ti-substituted zinc ferrite was estimated to be ∼30
nm. The elemental analysis as obtained from EDAX is in close agreement with the starting composition used for the synthesis. Vibrating sample magnetometer (VSM) studies indicated that this sample is ferrimagnetic in nature at room temperature.
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► Novel Ni1−xCuxMn2O4 manganite system. ► Sol–gel method for synthesis. ► VSM analysis.
The nanocrystalline Ni1−xCuxMn2O4 (x=0, 0.25, 0.5, 0.75 and 1) manganites were synthesized by ...sol–gel autocombustion method. X-ray diffraction technique confirmed the formation of single phase cubic spinel structure for all the compositions studied. Lattice parameter values show a decreasing trend with an increase in Cu content. Thermal analysis of the precursor after autocombustion was carried out using TG–DTA technique. Formation of spherical nanoparticles was revealed by scanning electron microscopy (SEM). The elemental analysis as obtained by EDAX is in close agreement with the expected composition from the stoichiometry of reactant solutions used. The nano-sized grain structure formation was confirmed by transmission electron microscopy (TEM). The magnetic data indicates that, all the compositions are ferrimagnetic in nature. The detailed results of XRD, thermal analysis, SEM, EDAX, TEM, electrical and magnetic properties indicating the role of substitution of copper ions on the structural, electrical and magnetic properties of nickel manganite are presented.
This is a novel way of synthesis with a unique combination of the chemical sol–gel and combustion process. The process is simple, inexpensive and less time consuming as compared to other wet chemical ...methods which resulting a nano-sized, homogeneous, highly reactive powder. The results revealed that the nitrate–citrate gel exhibits self-propagating combustion behaviour. The structural and electrical properties of the compounds were studied. X-ray diffraction measurements confirm the formation of single phase cubic spinel structure. We note a nonlinear relationship between the structure and composition due to Ni, which demonstrates that structural properties are strongly tied to the Ni substitution.
To determine overall and age-specific incidence rates of AD in a rural, population-based cohort in Ballabgarh, India, and to compare them with those of a reference US population in the Monongahela ...Valley of Pennsylvania.
A 2-year, prospective, epidemiologic study of subjects aged > or =55 years utilizing repeated cognitive and functional ability screening, followed by standardized clinical evaluation using the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, and the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for the diagnosis, and the Clinical Dementia Rating scale for the staging, of dementia and AD.
Incidence rates per 1000 person-years for AD with CDR > or =0.5 were 3.24 (95% CI: 1.48-6.14) for those aged > or =65 years and 1.74 (95% CI: 0.84-3.20) for those aged > or =55 years. Standardized against the age distribution of the 1990 US Census, the overall incidence rate in those aged > or =65 years was 4.7 per 1000 person-years, substantially lower than the corresponding rate of 17.5 per 1000 person-years in the Monongahela Valley.
These are the first AD incidence rates to be reported from the Indian subcontinent, and they appear to be among the lowest ever reported. However, the relatively short duration of follow-up, cultural factors, and other potential confounders suggest caution in interpreting this finding.
First report of chikungunya from the Maldives Yoosuf, Abdul Azeez; Shiham, Ibrahim; Mohamed, Ahmed Jamsheed ...
Transactions of the Royal Society of Tropical Medicine and Hygiene,
02/2009, Letnik:
103, Številka:
2
Journal Article
Recenzirano
An outbreak, characterised by fever, arthralgia and myalgia, in Malé and other islands of the Maldives began in December 2006. The illness was suspected as being due to chikungunya virus based on ...clinical symptoms and the prevailing chikungunya epidemic in the Indian Ocean region. The Department of Public Health initiated an investigation and collected blood samples from 67 patients; 21% were IgM-positive for chikungunya and 96% were PCR-positive. Six percent were positive for dengue by enzyme immunosorbent assay and 4% had evidence of dual infection. This is the first time that chikungunya fever has been confirmed in the Maldives. A total of 11
879 suspected and confirmed cases affecting 61% of inhabited islands (attack rate ranging from 0% to 72% on individual islands) were reported by the end of the epidemic in April 2007.
To determine the prevalence of AD and other dementias in a rural elderly Hindi-speaking population in Ballabgarh in northern India.
The authors performed a community survey of a cohort of 5,126 ...individuals aged 55 years and older, 73.3% of whom were illiterate. Hindi cognitive and functional screening instruments, developed for and validated in this population, were used to screen the cohort. A total of 536 subjects (10.5%) who met operational criteria for cognitive and functional impairment and a random sample of 270 unimpaired control subjects (5.3%) underwent standardized clinical assessment for dementia using the Diagnostic and Statistical Manual of Mental Disorders-fourth edition diagnostic criteria, the Clinical Dementia Rating Scale (CDR), and National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria for probable and possible AD.
We found an overall prevalence rate of 0.84% (95% CI, 0.61 to 1.13) for all dementias with a CDR score of at least 0.5 in the population aged 55 years and older, and an overall prevalence rate of 1.36% (95% CI, 0.96 to 1.88) in the population aged 65 years and older. The overall prevalence rate for AD was 0.62% (95% CI, 0.43 to 0.88) in the population aged 55+ and 1.07% (95% CI, 0.72 to 1.53) in the population aged 65+. Greater age was associated significantly with higher prevalence of both AD and all dementias, but neither gender nor literacy was associated with prevalence.
In this population, the prevalence of AD and other dementias was low, increased with age, and was not associated with gender or literacy. Possible explanations include low overall life expectancy, short survival with the disease, and low age-specific incidence potentially due to differences in the underlying distribution of risk and protective factors compared with populations with higher prevalence.
Nanocrystalline NiFe2−xMnxO4 (2≥x≥0) ferrites were prepared by sol–gel method. X-ray diffraction patterns reveal that synthesized compounds are in single phase cubic spinel lattice for all the ...composition. The surface morphology of all the samples were studied by scanning electron microscopy. The particle size measured from transmission electron microscopy and X-ray diffraction patterns confirms the nanosized dimension of the as-prepared powder. The elemental analysis was carried out by energy dispersive X-ray analysis technique. Magnetic properties such as saturation magnetization, coercivity and remanence are studied as a function of increasing Mn concentration at room temperature. The saturation magnetization shows a decreasing trend with increase in Mn content. The substitution of manganese in the nickel ferrite affects the structural and magnetic properties of cubic spinels.
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•NiFe2−xMnxO4 system was synthesized by a chemical combustion route.•All samples shows cubic phase.•All the synthesized ferrospinels are in nanocrystalline form.•The saturation magnetization decreases with increase in Mn content.
Objectives: To identify predictors of institutionalization in a community‐based cohort of older adults.
Design: Prospective, longitudinal. After initial assessment at study entry, surviving ...participants were reassessed in a series of approximately biennial waves until October 2001; baseline for the current analysis was Wave 2 (1989–91).
Setting:
Largely rural, blue‐collar community in the mid‐Monongahela Valley of southwestern Pennsylvania.
Participants: A population‐based cohort of 1,147 adults, aged 66 and older (mean 74.1) at baseline, who were not already institutionalized and who had complete data on all variables of interest.
Measurements: Cox proportional hazards models were used to identify predictors of institutionalization from among selected variables measured at baseline, including age, sex, education, marital status, living arrangements, ability to perform instrumental activities of daily living (IADLs), depressive symptoms, number of prescription medications (as an index of overall morbidity), self‐reported social support, hospitalization during the preceding year, and cognitive functioning. Dementia was defined according to the operational criteria of the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised, and by a Clinical Dementia Rating of 0.5 or greater, based on a standardized clinical assessment. The outcome variable was institutionalization, defined as entry into in a nursing home.
Results: Significant predictors of institutionalization were dementia (hazard ratio (HR)=5.09, 95% confidence interval (CI)=2.92–8.84), measured as a time‐dependent variable; older age (HR=1.06, 95% CI=1.03–1.10); IADL disability (HR=1.31, 95% CI=1.15–1.50); worse/less social support (HR=1.27, 95% CI=1.10–1.46); and number of prescription medications (HR=1.21, 95% CI=1.11–1.32), measured at baseline. The interaction between number of prescription drugs and dementia was also significant, suggesting that prescription medication count had less effect on institutionalization in those with dementia than in those without.
Conclusion: Dementia emerged as the most potent risk factor for institutionalization in this 12‐year community‐based epidemiological study. Medical burden conferred greater vulnerability to institutionalization in nondemented persons than in those with dementia.
Titanium substituted Zn–Mn ferrites were prepared by sol–gel route. Formation of single phase cubic spinel structure for all the compositions was confirmed from their X-ray diffraction studies. These ...ferrite samples existed as uniform and homogenous grain size as observed from scanning electron microscopy technique (SEM). The magnetic studies indicated that, the ferrimagnetic behavior increases with titanium substitution. Dielectric constant and complex impedance were measured as a function of frequency in the range 20Hz–1MHz. Frequency dependence of dielectric constant shows dielectric dispersion due to the Maxwell–Wagner type of interfacial polarization and impedance study reveals that the electrical conduction in the ferrites is by the interior of the grain boundaries. In general, the substitution of titanium plays an important role in changing the structural, magnetic and electrical properties of these ferrites.
•Nanocrystalline Ti substituted Zn–Cr ferrite sample.•Cubic spinel structure.•ZnMnFeO4 shows high dielectric permittivity.•All samples are ferromagnetic at low applied fields.
