Antibacterial fluorinated silica colloid superhydrophobic surfaces

A superhydrophobic xerogel coating synthesized from a mixture of nanostructured fluorinated silica colloids, fluoroalkoxysilane, and a backbone silane is reported. The resulting fluorinated surface was characterized using contact angle goniometry, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Quantitative bacterial adhesion studies performed using a parallel plate flow cell demonstrated that the adhesion of Staphylococcus aureus and Pseudomonas aeruginosa was reduced by 2.08 ± 0.25 and 1.76 ± 0.12 log over controls, respectively. This simple superhydrophobic coating synthesis may be applied to any surface, regardless of geometry, and does not require harsh synthesis or processing conditions, making it an ideal candidate as a biopassivation strategy.     

Changes in adsorbed fibrinogen upon conversion to fibrin

The conversion of adsorbed fibrinogen to fibrin in the presence of the enzyme thrombin was studied using surface plasmon resonance (SPR), a quartz crystal microbalance (QCM), sum frequency generation (SFG), atomic force microscopy (AFM), and an elutability assay. Exposure of adsorbed fibrinogen to thrombin resulted in a mass loss at the surface consistent with fibrinopeptide release and conversion to fibrin. Changes in hydration upon conversion of adsorbed fibrinogen to fibrin were determined from comparisons of acoustic (QCM) and optical (SPR) mass adsorption data. Conversion to fibrin also resulted in the adsorbed layer becoming more strongly bound to the surface and more compact. The elutability of adsorbed fibrinogen by Triton X-100, studied with SPR, decreased from 90 +/- 5 to 6 +/- 2% after conversion to fibrin. The height of the adsorbed monolayer, as determined by AFM, decreased from 5.5 +/- 2.2 to 1.7 +/- 0.8 nm. We conclude that thrombin-catalyzed fibrinopeptide release triggers significant changes in fibrinogen conformation beyond peptide cleavage.     

Water-soluble nitric oxide-releasing gold nanoparticles

The synthesis and characterization of water-soluble nitric oxide (NO)-releasing monolayer-protected gold clusters (MPCs) are reported. Tiopronin-protected MPCs ( approximately 3 nm) were functionalized with amine ligands and subsequently exposed to 5 atm of NO to form diazeniumdiolate NO donors covalently bound to the gold MPC. Diazeniumdiolate formation conditions, NO-release, and nanoparticle stability were examined as a function of the structure of the protecting ligand, pH, and storage time. Despite their aqueous solubility, proton-initiated decomposition of the diazeniumdiolate-modified Tio-MPCs resulted in only modest NO-release (<0.023 micromol/mg) for short durations (<1.5 h). To increase the NO storage capacity of gold nanoparticles, polyamine-stabilized MPCs ( approximately 5 nm) were synthesized with significantly enhanced NO-release properties (0.386 micromol/mg) and durations (up to 16 h). Transmission electron microscopy, thermogravimetric analysis, nuclear magnetic resonance spectroscopy, elemental analysis, and UV-vis spectroscopy were used to characterize both nanoparticle systems before and after NO exposure. The MPCs represent the smallest water-soluble NO-release nanoparticles to date (3-5 nm).     

The analysis of alkyl-capped alcohol ethoxylates and alcohol ethoxycarboxylates from alcohol ethoxylates by atmospheric pressure chemical ionization mass spectrometry

Alcohol ethoxylates (AEs) are nonionic surfactants. They are industrially important compounds that have historically been difficult to analyze, with the best results to date achieved through derivatization (e.g., silylation) followed by analysis by gas chromatography/mass spectrometry (GC/MS). Recently, mass spectrometric techniques such as field desorption (FD), time-of-flight secondary ion mass spectrometry (TOF-SIMS), fast atom bombardment (FAB), electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) have been employed to analyze surfynol(R) 4xx. In an effort to produce low-cost alkyl-capped AEs and anionic detergents from AEs, a fast and reliable measure of the product yields and conversions from AEs is required in research. We found that the product yields and conversions from reactions of AEs, obtained by the employment of atmospheric pressure chemical ionization (APCI), were in good agreement with those obtained from proton nuclear magnetic resonance spectroscopy ((1)H-NMR). Therefore, APCI can be used as a validated tool for studying AE reactions. Mixtures that contain either silylated or unsilylated ethoxylates and/or carboxylates yield the same APCI mass spectra. Copyright -Copyright 1999 John Wiley & Sons, Ltd.     

Concept of multipole magnetic field rotation in ECRIS

The conventional type of magnetic well is formed by superposition of two types of magnetic field, axial bumpy field and radial multipole field. It is used to contain plasma that consists of neutrals, ions and electrons. These particles are in constant motion in the well and energetic electrons create plasma by violent collisions with neutrals and ions. The confined electrons are constantly heated by ECR technique in the presence of magnetic field. In this paper it has been shown theoretically that how the electron motion is influenced in terms of heating, containment and azimuthal uniformity of plasma, by the axial rotation of the multipole magnetic field [1,2]. Afterwards, the feasibility of achieving a rotating magnetic multipole field is discussed to some extent. And it is seen that it is not beyond the capability of the scientific community in the present scenario of the advanced technology. Presently, it can be achieved for lesser field and slightly larger size of the multipole electromagnet and can be used for improvement of the ECR ion source (ECRIS).     

Synthesis of nitric oxide-releasing gold nanoparticles

We report the synthesis of nitric oxide-releasing gold nanoparticles formed by place-exchange reaction of hexanethiol monolayer-protected clusters with diamine nitric oxide donor precursor molecules, which are subsequently converted to N-diazeniumdiolate NO donors. The nitric oxide release from the N-diazeniumdiolate-modified gold nanoparticles is tunable by varying the number and/or the chemical structure of the exchanged amine ligands. The size and stability of NO-releasing nanoparticles may prove useful for a range of biomedical and pharmaceutical applications.     

Optimizing head/media electrical characterization in the presence of skew at high track density

The skew angle causes a discrepancy in determining the reader-to-writer offset (RWO) when using different periodical patterns in track profile tests. It also separates the peak overwrite (OW) from the peak high frequency amplitude HFA, (1 T periodical pattern) on corresponding track profiles. Furthermore, higher track density and larger skew angle exacerbate the skew effect and induce more RWO error, thus impacting the parametric performance optimization. Simulation studies are used to interpret the skew effect on the RWO determination and OW cross-track characteristics. Based on experimental investigations and simulation analyses, using the HFA, track profile for deriving the optimal RWO is proposed for spin-stand tests. Actual parametric characterization has proven that the optimal RWO minimized the skew effect and the RWO error, thus improving the parametric performance and reducing the test variation. The method is beneficial and necessary for the high track density characterization.     

Structurally Diverse Nitric Oxide-Releasing Poly(propylene Imine) Dendrimers

Structurally diverse secondary amine-functionalized poly(propylene imine) (PPI) dendrimers capable of tunable nitric oxide (NO) release were synthesized in a straightforward, one-step manner using ring-opening or conjugate-addition reactions with propylene oxide (PO), styrene oxide (SO), acrylonitrile (ACN), poly(ethylene glycol) methyl ether acrylate (average Mn = 480) (PEG) or 1,2-epoxy-9-decene (ED). N-Diazeniumdiolate nitric oxide donors were formed on the resulting secondary amine-functionalized G2-G5 PPI dendrimers by reaction with NO gas in basic solution. The NO storage and release kinetics for the resulting dendritic scaffolds were diverse (0.9-3.8 μmol NO/mg totals and 0.3 to 4.9 h half lives), illustrating the importance of the exterior chemical modification (e.g., steric environments, hydrophobicity, etc.) on diazeniumdiolate stability/decomposition. Tunable NO release was demonstrated by combining two donor systems on the exterior of one macromolecular scaffold. Additionally, a mathematical model was developed that allows for the simulation of dual NO release kinetics using the NO release data from the two single NO donor systems. The approaches described herein extend the range and scope of NO-releasing macromolecular scaffolds by unlocking a series of materials for use as dopants in biomedical polymers or stand-alone therapeutics depending on the exterior modification.