Synthesis and characterisation of 4-picrylamino-2,6-dinitrotoluene (PADNT): a new insensitive explosive

A chemoselective reductive method has been achieved for the preparation of 4-picrylamino-2,6-dinitrotoluene (PADNT), a new insensitive energetic material which has been characterised by spectral data and elemental analysis. Some explosive properties of the compound have also been determined and the results indicate that PANDT is quite safe to impact and friction.     

Biomechanics of atherosclerotic plaque

Atherosclerosis is the leading cause of death in the U.S. In balloon angioplasty, pressure is applied directly to atherosclerotic plaque to reopen the occluded blood vessel. The mechanical behavior of the plaque often determines the outcome of the angioplasty. Little information on the material properties of atherosclerotic plaque is available, yet the properties govern the plaque's behavior. Our discussion of the experimental testing and numerical analysis of plaque is directed toward summarizing the current knowledge of plaque material properties. Atherosclerotic plaque exhibits a wide range of behaviors consistent with the variability in the underlying composition. Overall, plaques exhibit nonlinear and inelastic mechanical behavior, although geometry and material properties are not well known. The histomorphological composition is critical in determining the plaque's mechanical response. Finite element approximations have been used to study the stresses developed in the diseased vessel; however, material properties are a critical component of a finite element analysis: the predictive capabilities depend on how accurately the material is modeled. When more information on plaque behavior is generated through careful and extensive experimental investigations, better models will be constructed to more accurately predict plaque responses. As the biomechanics community learns about plaque mechanics, we can use the knowledge to enhance the reliability of interventional procedures.     

Synthesis of novel copoly(ether ether ketones): Property evaluation and microstructure analysis by NMR

A series of copolymers were prepared by the reaction of various bisphenols with a 50:50 molar ratio of two bisfluoro compounds, 4,4′‐bis(1‐fluoro‐2‐trifluoromethyl benzyl) benzene and 4,4′‐difluorobenzophenone. The synthesized polymers were well characterized for their thermal, mechanical, and electrical performances. The copolymers showed a better set of properties than their analogous homopolymers derived from 4,4′‐bis(1‐fluoro‐2‐trifluoromethyl benzyl) benzene and bisphenols. The microstructures of the copolymers were analyzed by ¹H‐, ¹³C‐, ¹⁹F‐, distortionless enhancement by polarization transfer 90, two‐dimensional ¹H–¹H homonuclear correlation spectroscopy, and ¹³C–¹H correlation spectroscopy NMR techniques. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1292–1305, 2005     

GMR in Ni/Cu multilayers: an electronic structure study

Ab initio self-consistent semi-relativistic spin-polarized TB-LMTO energy band calculations have been carried out on Ni/Cu(100) multilayers, to study the in-plane as well as perpendicular to plane giant magnetoresistance (GMR) effects. The magnetic interaction energies, evaluated as a function of layer thickness, indicate that the antiferromagnetic ordering is a possible ground state for manifestation of GMR. Using the density of states at Fermi level and the Fermi velocity, GMR has been estimated as a function of the Cu spacer thickness.     

Processable aromatic polyesters based on bisphenol derived from cashew nut shell liquid: synthesis and characterization

The miscibility of chitosan/poly(ethylene oxide) (CS/PEO) blends was investigated by a combination of experiment and molecular simulation. Results from X-ray diffraction (WAXD) and thermal analysis (DSC) suggest that the maximum miscibility was seen at the PEO weight fraction (w _PEO) =0.2; the optimum stoichiometric ratio for CS and PEO functional groups. The change in vibrational frequencies from infrared spectra was attributed to the specific interaction between PEO ether oxygen with the amino and hydroxyl groups of CS. Radial distribution functions (RDF) from MD simulation suggest that all CS functional groups (NH₂, C3-OH, and C6-OH) can interact with PEO ether groups for which NH₂ has the highest activity. For CS hydroxyl groups, a more significant contribution of C6-OH rather than C3-OH groups that interact with PEO ether oxygen was observed. The interaction parameter (χ) determined from MD simulation was in good agreement with that of the DSC experiment (χ_CS-PEO?=?-0.21). Based on a comparison between χ and χ _critical , CS/PEO blend was predicted to be miscible for w _PEO <0.58 with a maximum at w _PEO =0.2. In addition, the order parameter from the mesoscale simulation was employed to monitor the phase separation in these blends. From MesoDyn simulation, the miscibility was decreased with increasing PEO content, and miscible CS/PEO blends were obtained only with w _PEO <0.58, in good agreement with MD simulation and experiment.     

Rapid biological synthesis of silver nanoparticles using Kalopanax pictus plant extract and their antimicrobial activity

Silver nanoparticles (AgNPs) have promising potential in biomedicine, energy science, optics, and health care applications. We synthesized AgNPs using plant, Kalopanax pictus leaf extract. UV-visible spectrophotometric study showed the characteristic peak for AgNPs at wavelength 430 nm. The optical density at 430 nm increased after addition of plant leaf extract, indicating increase in formation of nanoparticles. Comparative time course analyses for AgNP synthesis carried out at different reaction temperatures (20, 60, and 90 °C) revealed higher reaction rate for K. pictus than Magnolia kobus plant leaf extract, which showed highest AgNP synthesis rate in the previous report. Electron microscopy analyses confirmed the presence of well dispersed AgNPs, predominantly with spherical shapes. In transmission electron microscopy, the particle size decreased with increase in temperature. Electron dispersive X-ray spectroscopy analyses indicated that Ag content increased with increase in reaction temperature. Fourier transform-infrared spectroscopy studies revealed capping of bioorganics from plant to the synthesized AgNPs. The antimicrobial activity of the synthesized AgNPs against Escherichia coli increased with increase in reaction temperature. The observations in this study will prove beneficial in approaching rapid synthesis of AgNPs and their antimicrobial application.     

Lignocellulosic and marine biomass as resource for production of polyhydroxyalkanoates

Polyhydroxyalkanoates (PHAs) are considered as sustainable ‘green/bio plastics’ because they have potential to replace their depleting petroleum-based competitors in the recent future. To reach this goal, PHAs must be able to compete with the established petroleum-based plastics in both technical and economic aspects. The current PHA production is based on high-priced substrates of high nutritional value and simple carbon sources such as glucose, sucrose, starch, or vegetable oils. Non-food based carbon-rich complex polysaccharides of lignocellulosic and marine biomass can be used as alternative and suitable feedstock through consolidated bioprocessing (CBP). CBP is a promising strategy that involves the production of lytic enzymes, hydrolysis of biomass, and fermentation of resulting sugars to desired products in a single process step. CBP offers very large cost reductions if microorganisms possessing the abilities are found or microbial processes are developed to utilize substrate and simultaneously produce products. This review focuses on possible available complex polysaccharides of lignocellulosic and marine biomass that can be used as resources to produce PHAs in biorefineries, including CBP.     

Effect of grain hardness on bioavailability of iron in wheat as determined using the coupled invitro digestion/Caco-2 model

The impact of grain hardness on iron bioavailability from a set of wheat genotypes with varying hardness indices was determined. This may help us to consider grain hardness as an important parameter along with other established parameters for selecting food crops for future biofortification programs to combat iron deficiency linked to global health problem. The bioavailability and dialysability of iron were determined using the coupled in vitro digestion/Caco-2 model. The grain hardness and its molecular basis along with grain iron, phytate and inorganic phosphorous (Pi) contents were also evaluated. The data indicated that iron concentration in the genotypes ranged from 21 to 50 μg/g of dry matter. The hardness indices varied from as low as 28 for the derivative BTC17 to as high as 92 for the landrace IITR 26, almost similar to that of WL711, a wild type cultivar considered as control in this study. Low variability was however observed for the phytate and Pi contents. A significant negative correlation was observed between grain hardness vs. dialysability (r = −0.73) and bioavailability (r = −0.75) of iron. The results suggest that the hardness index which profoundly affects milling process, particle size of flour, milling yield and end-use also influences dialysability and bioavailability of iron from wheat.     

Computer modelling of the interaction between human choriogonadotropin and its receptor

Primary structural homology between the hormone binding siteof the LH/CG receptor and the enzyme binding site of chymotrypsininhibitor has been identified. This has led to the applicationof a knowledge-based approach of molecular modelling to describethe interaction of choriogonadotropin (CG) with the LH/CG receptor.A tertiary structural model for the mode of recognition betweenthe hormone and the receptor has been proposed. As in othersuch processes at the molecular level, the recognition betweenCG and its receptor is mediated through non-covalent interactions.The specificity of recognition is achieved by complementarityin van der Waals surfaces, hydrogen bonding and non-polar associations.The model shows nine hydrogen bonds between the hormone andthe receptor involving polar side chains as well as backboneamine and carbonyl groups. A hydropbobic cluster involving sidechain groups at the interface is also important in stabilizationof the intermolecular interactions