Ferrofluid non-Darcy heat transfer involving second law analysis: an application of CVFEM

Journal of Thermal Analysis and Calorimetry - The non-Darcy heat transportation of the ferrofluid together with the entropy generation has been studied in a permeable zone under the role of...     

Mössbauer studies and magnetic studies of Ni doped orthoferrites PrFe1−xNixO3 (x≤0.3)

The magnetic properties of polycrystalline PrFe_1−xNi_xO₃ (x≤0.3) system were studied using Mössbauer spectroscopy and magnetization measurements. The Mossbauer spectra exhibit six line spectra which loses its sharpness as the Ni substitution increases within the system. As the Ni concentration in the system increases, the hyperfine field and isomer shift shows decrease, which is vivid from the sluggish nature of the sextets. The small value of quadrupole splitting confirms the octahedral environment of the Fe⁺³ ions. The magnetization curves show the reversible behavior and represent the fall in negative molecular field leading to AFM frustration. From these results, we conclude that sagging in the spectra reveals the change from antiferromagnetic state to ferromagnetic state, which can be attributed to mixed state of Fe⁺³ ions i.e. high spin (HS) and low spin (LS) which is a consequence of progressive collapse of Hund’s rule due to HS→LS transition. These results confirm the weak ferromagnetic component due to canted-AFM spin arrangement of Fe³⁺ magnetic moments.     

In vitro study of cell death with 5-aminolevulinic acid based photodynamic therapy to improve the efficiency of cancer treatment

Photodynamic therapy (PDT) is a kind of photochemo therapeutic treatment that exerts its effect mainly through the induction of cell death. Distinct types of cell death may be elicited by different PDT regimes. In this study, efforts are underway to optimize PDT protocols for improved efficacy and combination of all three PDT mechanisms involved in the different human carcinomas cell narcosis. Our in vitro cell culture experiments with 5-aminolevulanic acid (ALA) a clinically approved photiosensitizer (PS) and 635 nm laser light have yielded promising results, as follow: (1) (human cervical cancer (HeLa) cell line incubated, for 18 h, with 30 μg/ml of 5-ALA, treated with laser light dose of 50 J/cm² can produce 85% of cell killing (2) human larynx carcinoma (Hep2c) cell line incubated, for 7 h, with 55 μg/ml of 5-ALA, treated with laser light dose of 85 J/cm² can produce 75% of cell killing (3) human liver cancer (HepG2) cell line incubated, for 22–48 h, with 262 μg/ml of 5-ALA, treated with laser light dose of 120 J/cm² can produce 95% of cell killing (4) human muscle cancer (RD) cell line incubated, for 47 h, with 250 μg/ml of 5-ALA, treated with laser light dose of 80 J/cm² can produce 76% of cell killing (5) Human embryonic kidney (HEK293T) cell line incu-bated, for 18 h, with 400 μg/ml of 5-ALA, treated with laser light dose of 40 J/cm2 can produce 82% of cell killing confirming the efficacy of photodynamic therapy.     

In vitro studies of Photofrin® mediated photodynamic therapy on human rhabdomyosarcoma cell line (RD)

In the current study, the cytotoxic effects induced by the given photosensitizer (PS) on human rhybdomyosarcoma cancer cells (RD) as an experimental model were investigated. The experimental results like cytotoxic effects induced by the given PS on RD cells were dose dependent and the optimum concentration of Photofrin® (100 μg/ml) along with 120 J/cm² generates the maximum loss in cell viability which is almost 82%. The significant loss in cell viability is the result of interaction of suitable dose of laser light (630 nm of wavelength) with Photofrin®, after excitation of PS, production of reactive oxygen species (ROS), which leads to mitochondria damage and resulting of cell death (cell necrosis/cell apoptosis). Viability of controlled and treated RD cells with optimum dose of light (630 nm) has been assessed by neutral red assay (NRA) and cell damaging effect were verified by staining of mitochondria using Mitotracker® red as an efficient dye as well as reactive oxygen species (ROS) accumulation detection.     

M-mode swept source optical coherence tomography for quantification of salt concentration in blood: An in vitro study

We report the use of M-mode swept source optical coherence tomography (SS-OCT) for measuring sodium chloride (NaCl) salt concentrations in liquid phantoms and in drawn whole blood based on temporal dynamics of light scattering. The Brownian motion of scattering particle is affected due to the change in viscosity of liquid. An autocorrelation function was determined from the power spectrum of SS-OCT signal and then was fit by mono and double exponential function to obtain decorrelation time. These translational decorrelation times corresponding to translational diffusion coefficients enabled us to find the controlled viscosity of the medium. The viscosities of the media were compared with literature values and a fair/excellent agreement was observed. Thus, the technique has ability to quantify the salt levels in terms of viscosity in nonflowing medium suspensions and many research routes necessary to determine its potential for in-vivo applications.     

Bioassay studies of cobalt (II) complexes of modified diamine

Coordination compounds of modified diamine, the basic unit of which are ethylenediamine, with that of Co (II) are prepared. The modified diamines are ethylenediaceticacid (EDDA) and N,N,N,N-tetaraethylene-1,2-diamine (TEEDA). These diamines are characterized through ¹H-NMR, ¹³C-NMR, elemental analysis and IR techniques. Cobalt (II) complexes of these two ligands were prepared and characterized by physical measurements including elemental analysis, IR, UV-Visible, magnetic susceptibilities and conductance measurements. Antibacterial activities are also carried out in order to investigate the biological activity upon complexation. They were screened against four pathogenic bacteria like Escherichia coli, Pseudomonas aeroginosa, Klesbella pneumonia and Staphylococcus aureus. The results showed significant enhancement in activities.     

Adsorption of Pb(II) on a composite material prepared from polystyrene-alumina and activated carbon: Kinetic and thermodynamic studies

The ability of polystyrene-alumina-activated carbon composite as a synthetic adsorbent was investigated for the removal of Pb(II) ions from aqueous solutions. Various physico-chemical parameters such as pH, initial metal ion concentration, adsorbent dosage and contact time were studied. The optimum solution pH for the maximum adsorption of Pb(II) was found to be 4. Kinetic data were best described by pseudo-second-order model. The adsorption process followed both Langmuir and Freundlich adsorption isotherms at 30 °C. Thermodynamic studies indicated that the adsorption was spontaneous and endothermic in nature. Desorption studies were carried out by batch and column operations and it was found that 97% Pb(II) could be recovered by the column process using 0.1 M HCl as eluent.     

Impact of substrate on some physical properties of PrFe0.5Ni0.5O3 thin films

We carried out the structural, morphological and transport study of PrFe_0.5Ni_0.5O₃ thin films prepared by pulsed laser deposition (PLD) over various substrates. Different substrates like LaAlO₃ (001),GaAs(001) and Si(001) were used for deposition to understand effect of lattice mismatch on various physical properties. The film deposited on LaAlO₃ was of best quality with well (001)-oriented and having good crystalline properties. Whereas, film deposited on GaAs(001) is well textured. Both films shows semiconducting behavior and resistance of the film deposited on GaAs(001) shows larger than that of film deposited on LAO. However, film deposited on Si, also shows polycrystalline growth with unusual metallic behavior. We tried to correlate this behavior with strain-induced growth of these films. Other possibilities for this unusual trend is also explored.