Synthesis and characterization of hydroxy‐bisphosphonate micrometer‐sized particles by dispersion polymerization of a new styrylbisphosphonate monomer

Bisphosphonates (BPs) are nonhydrolyzable pyrophosphate (P‐O‐P) analogs possessing two phosphonate groups linked to a single carbon (P‐C‐P). The hydroxy‐bisphosphonates (hydroxyBPs) are obtained when the hydroxy group is also linked to this bridging carbon. Their ability to form bidentate or tridentate chelates with calcium ions results in a high affinity to hydroxyapatite (HAP) in dentin, enamel and bones. In this study, we designed and prepared crosslinked poly(styrylbisphosphonate) (PStBP) micrometer‐sized particles by dispersion polymerization of the styrylbisphosphonate (StBP) and ethylene glycol dimethacrylate (EDMA) monomers. The new StBP monomer was synthesized in an efficient one‐pot synthesis using tris(trimethylsilyl)phosphite as the phosphorus source followed by methanolysis. The StBP monomer was successfully isolated and characterized as tri‐sodium salt. Polymerization of the StBP monomer was carried out in two steps: in situ conversion of the tri‐sodium StBP monomer back to its acid form, followed by radical dispersion polymerization in the presence of the crosslinker EDMA monomer. The resulting crosslinked PStBP micrometer‐sized particles retained the unique high affinity of the hydroxy‐bisphosphonate side groups to calcium ions and exhibited good adhesive properties to HAP. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Engineering of new crosslinked near‐infrared fluorescent polyethylene glycol bisphosphonate nanoparticles for bone targeting

Bisphosphonates (BPs) are nonhydrolysable pyrophosphate analogs with high affinity to hydroxyapatite (HAP, bone mineral) and are mainly used for treatment of various bone diseases. In this study, we designed and prepared crosslinked BP nanoparticles by dispersion copolymerization of three monomers: methacrylate PEG bisphosphonate, N‐(3‐aminopropyl) methacrylamide, and tetra(ethylene glycol) diacrylate. The size and size distribution of these PEG‐BP nanoparticles were controlled by changing various polymerization parameters. These BP particles possess dual functionality: covalent attachment of a dye (e.g., near IR fluorescent dye) or drug to the nanoparticles through the primary amine groups belonging to the aminopropyl methacrylamide monomeric units and chelation to the bone mineral HAP through the BP groups belonging to the methacrylate PEG bisphosphonate monomeric units, for enhanced long term bone‐targeted imaging and therapy applications. Body distribution of the optimal crosslinked BP nanoparticles was tested on a chicken embryo model via intravenous administration. This study indicated that the fluorescence intensity of the all organs (e.g., blood, spleen, liver, kidney, and heart) except the bones decreased significantly within 48 h (p < 0.05) while that of the bones hardly changed over that time (p > 0.05). © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4282–4291     

Duality,crossing and MacLane’s coherence

It is shown that MacLane’ rectangle, pentagon and hexagon identities in category theory, when applied in particle physics to duality diagrams or to rational conformal field theories in two dimensions, yield the necessary physical algebraic constraints. Supported in part by DOE grant no. DE-FG05-85ER40200 Supported by US-Israel BSF grant 87-00009/1.     

Formation and structural heat-stability of β-lactoglobulin/surfactant complexes

The binding of two model surfactants, sodium dodecyl sulfate and dodecyltrimethylammonium bromide to β-lactoglobulin was studied at room temperature and the thermal stability of the resulting complexes was evaluated by differential scanning calorimetry (DSC) measurements. Binding isotherms indicated both ionic and hydrophobic interactions depending on both the charge of the protein and surfactant at different pHs and on the binding molar ratios of surfactant to the globular protein. Zeta potential measurements indicated charge neutralisation of the protein, under suitable conditions, which also lead to aggregation and precipitation of the proteins. Surface tension measurements indicated similarity between the two types of oppositely charged protein-surfactant complexes and a difference between them when protein and surfactants are similarly charged. DSC measurements revealed different behavior in protein conformation in the presence of the two surfactants. The results obtained at room temperature and upon heating are discussed in terms of the nature of the surfactant/protein interactions involved in the complex formation.     

Spatial decay theorems for nonlinear parabolic equations in semi-infinite cylinders

Classes of nonlinear parabolic equations in a semi-infinite cylinder are considered. The equations are of the form $$u,_{jj} + g_{ij} \left( {x,u,p,\partial ^2 u} \right)u,_i u,_j = c\left( {x,u,p} \right)\frac{{\partial u}}{{\partial t}},$$ wherep=u, _k u, _k and? ² u represents a general space derivative of second order. Homogeneous Dirichlet data are prescribed on the lateral sides of the cylinder for all time, along with zero initial data. At any fixed timet, the solution is assumed to be bounded throughout the cylinder, as is the corresponding symmetric matrixg _ij . Under these assumptions, it is proved that each solution decays pointwise exponentially to zero with distance from the face of the cylinder and the exponential decay rate depends only upon the cross-section of the cylinder, but not upon time or the bounds foru andg _ij . In addition, if the boundary data on the face of the cylinder satisfy certain mild smoothness conditions, one obtains a decay rate equal to the best possible rate for the Laplace equation.     

Low‐density polyethylene films doped with europium(III) complex: their properties and applications

Light‐converting polyethylene film containing europium(III) complex with phenanthroline was manufactured under an extrusion process. The film was characterized first by means of time‐of‐flight secondary‐ion‐mass spectrometry (TOF‐SIMS), ultraviolet‐visible‐infrared (UV‐vis‐IR) spectroscopy, then a study of excitation and luminescence spectra, quantum yield and lifetime of luminescence. The quantum yield of luminescence was measured as 5±2%, and the lifetime of luminescence was determined about 470 μsec. TOF‐SIMS surface mapping showed the uniform distribution of europium(III) over the film. Visualization of strong picosecond UV laser beams through the use of the developed film has been demonstrated. Copyright © 2004 John Wiley & Sons, Ltd.     

On the existence of acetyl hypofluorite

¹H and ¹⁹F NMR spectra along with GC studies of the oxidizing solution obtained from the reaction of F₂ with NaOAc, support the notion that a single compound with molecular structure CH₃COOF indeed exists.     

Taming elemental fluorine: Indirect use of fluorine for the synthesis of α-fluoroketones[1]

Fluorine and sodium trifluoroacetate react at ?75° to produce a variety of fluoroxy-compounds. Although it is possible to direct the reaction towards the formation of CF₃COOF or CF₃CF₂OF, mixtures may be used when only the electrophilic fluorine has to be attached to the molecule of interest. Such is the case of the reaction of enol-acetates with the mixture of the fluoroxy reagents. A wide variety of compounds, including steroids and containing various functional groups, were tested. In most cases the desired α-fluoroketones were obtained in good to very good yields. The new fluorine containing compounds are the compounds numbered $\text{2, 9, 11, 13, 15, 16}$ and $\text{20}$.     

Balancing the Failure Modes in the Electronic Circuit of a Cardiac Pacemaker: A Decision Analysis

Cardiac pacemaker malfunctions are of continuous concern to the medical profession as well as to the electronics industry. Certain failures in cardiac pacemaker performance are critical and can result in patient deaths. Cardiac pacemakers are vulnerable to certain malfunctions in the electrode, batteries and the electronic circuit. This paper focuses on failures and reliability of the electronic circuit and how they affect its choice and design. The paper discusses the issues of balancing the various failure modes by considering both failure rates and failure outcomes. As the choice of an appropriate pacemaker is a decision problem under conditions of uncertainty, we employ decision analysis as the analytical and conceptual framework. Use of utility theory enables a systematic quantitative evaluation of such seeming intangibles as the various failure outcomes. Probabilities are assessed using specific engineering and reliability literature. The method is demonstrated on a choice problem between two specific electronic circuit designs. The methodology can be useful in designing the electronic circuit to meet certain reliability specifications, deciding whether or not to introduce redundancy, decisions affecting components and technology, and establishing minimal reliability standards, with regard not only to cardiac pacemakers but to other electronics as well.