The formation, structural, electrical, magnetic and Mössbauer properties of ferrispinels, Cd1−x Ni x Fe2O4

A series of Cd_1–x Ni _x Fe₂O₄ (where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were synthesized by the tartarate precursor method. The formation of these ferrispinels was studied by X-ray powder diffraction, infrared spectroscopy, electrical conductivity, thermoelectric power, magnetic hysteresis, initial magnetic susceptibility and Mössbauer spectroscopy. The temperature variation of the direct current electrical conductivity showed a definite kink (break) in the range 645 to 806 K except for x = 0 and x = 0.2 samples. The kink occurred in each curve (x 0.4) at a temperature which corresponds to the ferrimagnetic to paramagnetic transition. The thermoelectric power for all samples was negative over the whole range of temperature, indicating that the charge carriers are electrons (i.e. n-type semiconductivity). The compounds with x 0.4 showed a definite hysteresis loop. The composition dependence of the saturation magnetization (M _S) and magnetic moment (n _B) up to x = 0.8, has been explained on the basis of the existence of Yafet–Kittel angles on the B-site spins. The Néel's two sublattice model can be applied to the sample with x = 1. The Mössbauer spectra of compounds with x = 0.0 and 0.2 showed a paramagnetic doublet, while x = 0.4 and 0.6 exhibited a relaxation spectrum. The compounds with x 0.8 exhibited normal Zeeman split sextets at room temperature.     

Differences in the hormonal status of rats highly and poorly resistant to hypoxia

Rats were tested for hypobaric hypoxia and decapitated two weeks later at 9-12, 13-14 and 15-17 o'clock. The levels of corticosterone, insulin and testosterone were determined in serum by RIA. Great daily fluctuations and higher elevation of corticosterone level in response to additional 1.5-min hypoxia were observed in low hypoxia-resistant (HHR) rats. The correlation of corticosterone/insulin ratio was directly proportional in LHR rats and inversely proportional in HHR rats. No difference in testosterone and insulin levels in LHR and HHR rats was found.     

Evaluation of a large-scale frozen blood program

The characteristics of previously frozen red blood cells, prepared in a large-scale frozen blood program using the Red Cross method were evaluated. The use of the method as originally described resulted in approximately 91 per cent freeze-thaw-wash recovery of red blood cells. When the glycerolization step was modified by adding the partially glycerolized erythrocytes into 300 ml of 6.2M glycerol, freeze-thaw-wash recoveries were decreased. However, gradient addition of glycerol to the red blood cells without the use of stylet, resulted in acceptable in vitro recoveries. Thawing frozen units in waterbath, to which no antiseptic was added, could introduce bacteria into units of previously frozen red blood cells. Therefore, it seems advisable to use dry heat thawing procedures. Previously frozen red blood cells prepared in the large scale maintained normal levels of ATP and 2,3 DPG. Therapeutic transfusions had acceptable 24-hour survival in vivo.     

Synthesis of “stabilized Mn1−xMgxO” system (0.001 ⩽ x ⩽ 0.15) and its structural,thermal, optical and magnetic studies

A novel method of preparation, involving careful formation of a stoichiometric solid solution of stabilized Mn_1-x Mg _x O system for eight different concentrations ofx (0.001 x 0.15) is described. A variety of physicochemical techniques such as X-ray diffraction, DTA-TGA, reflectance spectra, magnetic susceptibility and XPS data are used to determine structure-property correlations in the solid solutions, which are (i) X-ray diffraction studies reveal the linear decrease of cubic lattice parameter with increasing x, (ii) DTA-TG-DTG studies which confirm the formation of solid solution and the stability of these solid solutions in air which increases from 515 to 565 K withx, (iii) the diffused reflectance spectra shows nearly perfect octahedral symmetry around Mn²⁺ ions, (iv) magnetic susceptibility data indicates the usual dilution effects of diamagnetic ions in antiferromagnetic host lattice, (v) XPS studies reveal the presence of mixed phase of Mn₂O₃-MgO on the surface which protects the bulk MnO from its further oxidation to higher oxides of manganese. This shows the important role of Mg²⁺ in the chemical passivation of manganous oxide.     

Formulation of silver chloride/poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (AgCl/PHBV) films for potential use in bone tissue engineering

Orthopedic implant failure due to bacterial infection has been a concern in bone tissue engineering. Here, we have formulated a composite made of biodegradable polymer, i.e., poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV), and silver chloride. Ag⁺ ions released from the AgCl/PHBV film can promote an aseptic environment by promoting inhibition of bacterial growth while maintaining bone cell growth, depending on AgCl loading. The objective of this study is to formulate AgCl/PHBV film(s) of varying composition so as to evaluate the dependence of AgCl loading in the film on antimicrobial activity and cytotoxicity. The release kinetics of silver ions from AgCl/PHBV film in aqueous and Dulbecco's Modified Eagle Medium showed similarity in the initial burst of ions during the first day of desorption followed by a gradual release of ions over extended time period. The antibacterial efficacy of AgCl/PHBV film against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa was evaluated by microbiological assay, while cytotoxicity of the film toward MC3T3‐E1 cells was determined by MTT assay. For all compositions studied, a clear zone of inhibition around AgCl/PHBV film was noticed on a modified Kirby‐Bauer disk diffusion assay. We established that MC3T3‐E1 cell attachment on AgCl/PHBV film is strongly related to loading of AgCl in the film. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45162.     

Synthesis and characterisation of chlorinated rubber seed oil alkyd resins

Rubber seed oil alkyd resins of 50% oil length were prepared (sample I) and parts of it modified by direct chlorination for 30 min (sample II), 60 min (sample III) and 90 min (sample IV). The concentration of the chloride ions was found to be 0.231, 0.236 and 0.239 mol/dm³ for samples II, III and IV, respectively. The IR spectra of the samples show that chlorine enters only into the aliphatic portion of the alkyd chain by addition. The physico-chemical properties and performance characteristics of the chlorinated and unchlorinated alkyd resins were determined. The results show that the chlorinated resins are fire retardant and that they possess superior drying properties, than the unchlorinated alkyds.     

Fibroadenomatoid hyperplasia: a cause of suspicious microcalcification on mammographic screening

Backscatter factors for orthovoltage x-ray beams are fitted with the expression BSF = 1 + ms/(s + n), where s is field size and m and n are adjustable parameters. The accuracy is better than 0.5%. Good results were also obtained for Cs-137 gamma rays at depth 0.12 cm and Co-60 gamma rays at depth 0.5 cm using the same expression, which failed, however, for peak scatter factors at high x-ray energies.