Effect of γ-irradiation on the transport and structural properties of polycrystalline Bi1.2 Pb0.33 Sr1.54 Ca2.06 Cu3 O10+δ superconductor

The effect of γ-irradiation on the transport and structural properties of polycrystalline Bi_1.2 Pb_0.33 Sr_1.54 Ca_2.06 Cu₃ O_10+δ superconductor, synthesized by nitrate route is studied. The sample has been irradiated by γ-ray upto a dose 400 MR using a ⁶⁰Co isotope source of 2 kCi strength with a dose-rate of 6.26 Gy/min. Its X-ray diffraction pattern, resistivity–temperature behaviour as well as elemental and morphological analyses using scanning electron microscope have been examined before and after the irradiation. It is observed that the normal state resistivity increases as the dose is increased. The transition width of the sample is found to get broadened with the increasing dose. Using the theories of Aslamazov–Larkin and Maki–Thompson, we present an analysis of the excess conductivity of our sample and the effect of γ-irradiation on it. It is found that the coherence length of the sample gets increased with the increase of the irradiation dose.     

Effect of tackifier and crosslinkers on electron beam curable polyurethane pressure sensitive adhesive

Polyurethane based pressure sensitive adhesive using monofunctional urethane acrylate and difunctional urethane acrylate has been made using electron beam irradiation. The effect of varying electron beam doses on the adhesion properties viz., peel adhesion, shear adhesion and initial tack has been studied. Effect of tackifier and crosslinkers viz., polymeric methylene diphenyl diisocynate, carbodiimide modified methylene diphenyl diisocynate and triallyl cynurate on adhesion properties as well as on moisture vapor transmission rate and gel content of the polyurethane based pressure sensitive adhesive has also been studied. It was found that with increasing dose, tackifier and crosslinkers concentration, all the adhesion properties viz., peel adhesion, shear adhesion strength and initial tack were increased upto a certain dose, concentration of tackifier and crosslinkers, reached a plateau and then levelled off with further increasing the dose, tackifier and crosslinkers concentration. Similarly, moisture vapor transmission rate was decreased and the gel content increased with increasing dose of electron beam.     

Glycal-ruthenium carbonyl clusters: Syntheses, characterization, and anticancer activity

Four new chiral ruthenium carbonyl cluster complexes Ru₃(μ-H)₂(CO)₉(L-2H) (1), Ru₃(μ-H)₂(CO)₇(L-2H)(dppm) (2), Ru₃(μ-H)₂(CO)₇(L-2H)(PPh₃)₂ (3), Ru₃(μ-H)₂(CO)₇(L-2H)(dppe) (4) containing a dehydrogenated form (L-2H) of 3,4,6-tri-O-benzyl-d-galactal (L) as a chiral ligand have been prepared and characterized. The anticancer activity of five compounds 1-4 and Ru₃(μ-H)₂(CO)₉(L-2H) 5 (L = tribenzyl glucal) against six types of human cancer cell lines was studied and compared to cisplatin. Compound 1 was chosen to produce more detailed growth curves based on overall highest activity profile. The structure of compound 2 was established by a single-crystal X-ray diffraction analysis. The structure based on triangular metal framework contains a bridging dehydrogenated tribenzyl galactal ligand bonded in a parallel μ₃-η²-bonding mode and a bridging dppm ligand. Variable-temperature NMR studies show that the two hydride ligands in compounds 1 and 2 are dynamically active on the NMR time scale at room temperature.     

Detection of algae and bacterial biofilms formed on titanium surfaces using micro-Raman analysis

Biofouling is one of the major impediments in the use of titanium in sea-water cooled condensers of power plants, which is otherwise an excellent material with respect to corrosion resistance. Raman microscopic experiments were carried out on biofilms grown on titanium surfaces to find out the chemical composition of complex extracellular polymeric substances (EPS) in the biofilm. Though the spectral resolution of normal Raman experiments on these systems was very poor, it was improved when micro-SERS experiments were carried out using mono and bimetallic Ag and Cu colloids. It was observed that spatial distribution of polysaccharides was higher than that of proteins in algae biofilms formed on titanium matrix. Similar experiments were performed on laboratory cultured bacterial films of Pseudomonas aeruginosa. It was evidenced that algal and bacterial biofilms on titanium can be clearly distinguished with the help of Raman mapping coupled with SERS technique using bimetallic Ag/Cu colloids.     

Phonon dispersion and heat capacity in poly(ε-caprolactone)

Normal mode of vibration and their dispersion for poly(ε-caprolactone) (PCL) chain have been obtained by using Urey-Bradley force field and the Wilson's GF matrix method as modified by Higgs. Characteristic features of the dispersion curves such as crossing, repulsion and regions of high density-of-states have been explained. Heat capacity measurements have been interpreted and the limitations of the present work discussed.     

Vibrational dynamics of polyurydilic acid

A study of the normal modes of vibration and their dispersion in polyurydilic acid (polyU) is reported using Wilson's GF Matrix method as modified by Higgs. This is done for the `bare' as well as for the helix `loaded' with uracil. Confusion that has prevailed regarding the assignments of the observed modes at 810 and 572 cm⁻¹ is cleared and it is shown that the so called bare helix (polyU-U) has a different minimum energy state and hence spectrally different. Dispersion of the normal modes in the two helices shows marked differences which are characteristic of the extent of electrical/mechanical coupling along the chain and between the chain and the base. Values predicted for the heat capacity as a function of temperature for polyU is also reported.     

NMR spectral studies: XIII—titanium tetrachloride-induced and lanthanide-induced shifts in the proton NMR spectra of β-lactams

2-Azetidinones which carry a proton each on C-3 and C-4 often pose a problem in the correct assignment of the resonances due to these protons; titanium tetrachloride has been shown to be an effective and reliable n.m.r. shift reagent to differentiate between these two protons on the basis of their different sensitivities to this reagent. A few compounds were also studied with Eu(fod)₃ and Pr(fod)₃ for the sake of confirmation.     

Correction to: Study of human blood under influence of magnetic field by AC dielectric and thermally stimulated discharge current methods

Journal of Thermal Analysis and Calorimetry - In the original publication of the article, Tables 1 and 2 were swapped. The correct versions are given below. The original article has been...     

Dynamics of Hollow Nanofiber Formation During Solidification Subjected to Solvent Evaporation

Summary: To mimic the emergence of gradient morphology in polymer nanofibers, a new theoretical approach has been developed in the context of Cahn‐Hilliard time evolution equation, alternatively known as time‐dependent Ginzburg‐Landau equation (Model B) involving concentration order parameter. The effects of solvent evaporation on the morphology evolution of the nanofibers have been demonstrated. The numerical simulation showed that the formation of skin layers is governed by the competition between solvent evaporation rate and mutual diffusion rate. That is to say the skin layers are formed in the nanotube whenever the rate of evaporation exceeds a critical value; otherwise, a solid fiber is formed. In hollow nanofibers, the layer can grow to a substantial fraction of the fiber diameter, allowing it to remain intact, albeit often in a collapsed form.

The cross‐sectional concentration profile of the emerging fiber.