Enhanced Néel temperature in Mn ferrite nanoparticles linked to growth-rate-induced cation inversion.

Mn ferrite (MnFe(2)O(4)) nanoparticles, having diameters from 4 to 50 nm, were synthesized using a modified co-precipitation technique in which mixed metal chloride solutions were added to different concentrations of boiling NaOH solutions to control particle growth rate. Thermomagnetization measurements indicated an increase in Néel temperature corresponding to increased particle growth rate and particle size. The Néel temperature is also found to increase inversely proportionally to the cation inversion parameter, delta, appearing in the formula (Mn(1-delta)Fe(delta))(tet)[Mn(delta)Fe(2-delta)](oct)O(4). These results contradict previously published reports of trends between Néel temperature and particle size, and demonstrate the dominance of cation inversion in determining the strength of superexchange interactions and subsequently Néel temperature in ferrite systems. The particle surface chemistry, structure, and magnetic spin configuration play secondary roles.

Synthesis of size-controlled cobalt ferrite particles with high coercivity and squareness ratio.

Cobalt ferrite particles with diameters ranging from a few micrometer to about 15 nm were synthesized using a modified oxidation process. The fine control of the particle size was achieved by introducing various concentrations of Fe(3+) ions at the beginning of the reaction. Among the particle sizes obtained by using this method, particles with a grain size of about 36 nm showed a magnetization (M(s)) of 64 emu/g and a maximum coercivity (H(c)) of 2020 Oe at room temperature. The corresponding squareness ratio was found to be 0.53.

Prevalence of diabetes and pre-diabetes and associated risk factors among tuberculosis patients in India.

BACKGROUND: Diabetes mellitus (DM) is recognised as an important risk factor to tuberculosis (TB). India has high TB burden, along with rising DM prevalence. There are inadequate data on prevalence of DM and pre-diabetes among TB cases in India. Aim was to determine diabetes prevalence among a cohort of TB cases registered under Revised National Tuberculosis Control Program in selected TB units in Tamil Nadu, India, and assess pattern of diabetes management amongst known cases. METHODS: 827 among the eligible patients (n = 904) underwent HbA1c and anthropometric measurements. OGTT was done for patients without previous history of DM and diagnosis was based on WHO criteria. Details of current treatment regimen of TB and DM and DM complications, if any, were recorded. A pretested questionnaire was used to collect information on sociodemographics, habitual risk factors, and type of TB. FINDINGS: DM prevalence was 25.3% (95% CI 22.6-28.5) and that of pre-diabetes 24.5% (95% CI 20.4-27.6). Risk factors associated with DM among TB patients were age (31-35, 36-40, 41-45, 46-50, >50 years vs <30 years) [OR (95% CI) 6.75 (2.36-19.3); 10.46 (3.95-27.7); 18.63 (6.58-52.7); 11.05 (4.31-28.4); 24.7 (9.73-62.7) (p<0.001)], positive family history of DM [3.08 (1.73-5.5) (p<0.001)], sedentary occupation [1.69 (1.10-2.59) (p = 0.016)], and BMI (18.5-22.9, 23-24.9 and ≥25 kg/m(2) vs <18.5 kg/m(2)) [2.03 (1.32-3.12) (p = 0.001); 0.87 (0.31-2.43) (p = 0.78); 1.44 (0.54-3.8) (p = 0.47)]; for pre-diabetes, risk factors were age (36-40, 41-45, 46-50, >50 years vs <30 years) [2.24 (1.1-4.55) (p = 0.026); 6.96 (3.3-14.7); 3.44 (1.83-6.48); 4.3 (2.25-8.2) (p<0.001)], waist circumference [<90 vs. ≥90 cm (men), <80 vs. ≥80 cm (women)] [3.05 (1.35-6.9) (p = 0.007)], smoking [1.92 (1.12-3.28) (p = 0.017)] and monthly income (5000-10,000 INR vs <5000 INR) [0.59 (0.37-0.94) (p = 0.026)]. DM risk was higher among pulmonary TB [3.06 (1.69-5.52) (p<0.001)], especially sputum positive, than non-pulmonary TB. INTERPRETATION: Nearly 50% of TB patients had either diabetes or pre-diabetes.