Binding affinity of fluorochromes and fluorescent proteins to Taxol™ crystals

The ability of Taxol (paclitaxel) to bind and stabilize microtubules is the basis for its use as an anti-mitotic drug as well as an additive for in vivo and in vitro studies of microtubules. The low solubility of Taxol in aqueous solutions, however, facilitates the formation of Taxol crystals that can be decorated with fluorescent tubulin. In cells treated with Taxol, these decorated Taxol crystals may be mistaken for self-assembled tubulin asters when observed with a fluorescent microscope. We confirmed via fluorescent and differential interference contrast microscopy that Taxol crystals can be decorated not only with fluorescent tubulin but also with other fluorescent proteins and fluorochromes without perturbing their morphology. We used theoretical calculations to further investigate Taxol-fluorescent agent interactions. Using computational docking studies we identified a new, potential Taxol binding site within the tubulin dimmer, allowing the interaction between crystalline Taxol and tubulin. Our calculations, however, show that fluorescent tubulin binding to Taxol crystals is more favorable via the fluorochromes covalently linked to the tubulin dimmers, rather than via the new Taxol-binding site, what is in accordance with our experimental data.     

osteoprotegerin-deficient mice develop early onset osteoporosis and arterial calcification

Osteoprotegerin (OPG) is a secreted protein that inhibits osteoclast formation. In this study the physiological role of OPG is investigated by generating OPG-deficient mice. Adolescent and adult OPG-/- mice exhibit a decrease in total bone density characterized by severe trabecular and cortical bone porosity, marked thinning of the parietal bones of the skull, and a high incidence of fractures. These findings demonstrate that OPG is a critical regulator of postnatal bone mass. Unexpectedly, OPG-deficient mice also exhibit medial calcification of the aorta and renal arteries, suggesting that regulation of OPG, its signaling pathway, or its ligand(s) may play a role in the long observed association between osteoporosis and vascular calcification.     

Preliminary characterization of a low-powered microwave induced flame plasma for direct organic solvent nebulization

A low powered (<90 W) microwave-induced plasma has been generated at atmospheric pressure by using a Beenakker cavity, a laboratory constructed torch, and a gas mixture of argon (400 ml/min), hydrogen (100 ml/min), and air (130 ml/min). This plasma has an excitation temperature of 3300-3500 K, electron number density of 7 × 10(14) cm(-3), and easily accepts direct methanol and ethanol introduction with a 1 ml/min solution nebulization rate. Detection limits (3σ) obtained from the atomic emission signals of Li, Sr, and Cr in water are 15, 120, and 290 ng/ml, respectively. Similarly, detection limits for the metals in methanol are 15, 120, and 260 ng/ml, respectively, and in ethanol they are 25, 360, and 330 ng/ml, respectively. The linear dynamic range is greater than three orders of magnitude.     

Interfacial mechanical behavior of 3D printed ABS

We describe an experimental approach for characterizing the local mechanical behavior of acrylonitrile butadiene styrene (ABS) structures processed through fused deposition modeling. ABS test specimens processed in various build orientations were subject to multiscale mechanical tests as well as local morphology and chemical analyses. Instrumented indentation, local dynamic mechanical analysis, and atomic force microscopy tests were used to explore the mechanical behavior and morphology of build surfaces and weld interfaces. An interfacial stiffening effect was found for the majority of the specimens tested, with up to a 40% increase in the indentation elastic modulus measured with respect to the build surfaces. Raman spectroscopy mapping of the interfacial areas revealed ～30% less butadiene/styrene and butadiene/acrylonitrile ratios with respect to analysis of the build surfaces. The results provide insight into the multiscale behavior of additive manufactured structures and offer the potential to guide processing–structure–property understanding of these materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43671.     

Transient Electromagnetic and Heat Transfer Characteristics of the MgB2 Superconductor in Liquid Helium

A transient current density analysis is carried out for the type II superconductor (SC) material MgB₂ in liquid Helium. Variable magnetic fields are used as the unknown in solving the curl-curl relations of the electromagnetic fields applying the finite element method (FEM) for 2D axis symmetric cylindrical wires. Assuming an exponential current rise, the magnetic flux, current density and temperature distribution in the SC and He are calculated. This study gives the limiting current values to avoid the normal state, the temperature distribution profile with time as well as the changes in the magnitude of the current and time constant. Oscillations and non-uniform temperature distributions are observed in He and in the SC respectively if one varies the parameters which are related to the different heat transfer mechanisms. A slight instability in the current distribution is also observed which might transfer to a thermal instability, i.e. could signal He boiling.