Particle Adhesion in Model Systems: 16. Barium Sulfate Particles on Glass and Protein Surfaces

The adhesion phenomena of monodispersed barium sulfate (BaSO₄) particles on gelatin-coated glass beads were evaluated using the packed column technique and compared with the same system in the absence of the protein.

Multilayer deposition was observed with the uncoated glass beads at pH 4, 5 and 6, while at pH 9, which is above the isoelectric point (pH ～ 6) of BaSO₄ particles, monolayer deposition took place, even though the BaSO₄ particles and glass beads bore the same sign of charge. At pH = 10, no uptake was observed on the glass beads, but the addition of 10^?4 mol dm^?3 BaCl₂ induced multilayer deposition due to the adsorption of the Ba²⁺ cation on BaSO₄ particles, which causes a reversal of their charge to positive.

The formation of multilayers was found to occur over a much wider pH range on the gelatin coated glass beads.

BaSO₄ particles deposited in multilayers could not be removed from either glass beads or gelatin-coated glass beads by rinsing the loaded column with solutions of pH 11.5, but could be detached from monolayers on glass beads only.     

Synthesizing alkali ferrates using a waste as a raw material

This study focused on the potential to transform a waste, hydrated iron sulfate, into a useful product. The waste was generated from titanium dioxide production and from the surface treatment of steel. Its disposal is restricted by environmental regulations, and consequently, it has to be recycled and/or treated. The described recycling was achieved through synthesis of potassium ferrate, which contains iron in a hexavalent state (Fe^VI). The synthesis process was achieved in a rotary reactor at room temperature using chlorine as an oxidant. The efficiency of potassium ferrate synthesis was about 60%. This paper presents details of the kinetics of the potassium ferrate synthesis. For more information, contact N. Kanari, Laboratoire Environnement et Minéralurgie, UMR 7569 CNRS, ENSG-INPL, BP 40, 54501 Vandœuvre, France; +33-383-596-343; fax +33-383-596-367; e-mail ndue.kanari@ensg.inpl-nancy.fr.     

Viscosity and density of isobutane measured in wide ranges of temperature and pressure including the near‐critical region

Accurate ηρpT data for isobutane were measured for nine isotherms between 298.15 and 498.15 K using simultaneously a vibrating‐wire viscometer and a single‐sinker densimeter. The maximum pressure was 93% of the saturated for subcritical isotherms and 30 MPa for supercritical isotherms. The density measurements are generally characterized by an uncertainty of ≤0.1%. Allocation errors for temperature and pressure influence significantly their uncertainty in the near‐critical region. A comparison with the equation of state by Bücker and Wagner shows agreement normally within ±0.1%. The near‐critical isotherm 410.15 K reveals differences to ?3.7% exceeding the uncertainty of 1.9%. The uncertainty in viscosity is ≤0.3%. The comparison with the correlation of Vogel et al. yields deviations exceeding the uncertainty of the correlation (3%). The critical enhancement becomes evident for the near‐critical isotherm amounting to 1.4%. The new data will improve the viscosity surface correlation. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3116–3137, 2015     

Preparation and properties of uniform mixed and coated colloidal particles

Colloidal dispersions of uniform spherical particles of zirconium basic sulphate and zirconium oxy-basic carbonate were prepared by ageing zirconium sulphate solutions at elevated temperatures in the presence of urea. Different chemical compositions of the above products resulted when the ageing temperature was altered. Depending on the nature of the original solids, calcination at 800° C resulted in the formation of tetragonal or monoclinic zirconia. Under certain conditions a mixed phase, including cubic zirconia, has also been identified. The particle morphology was retained during these transformations. Coprecipitation in mixed solutions of zirconium and yttrium salts aged at 80° C yielded composite spherical particles of basic carbonate with a zirconium to yttrium ratio of the solid similar to that used in the initial solution. Zirconium basic sulphate particles coated with yttrium basic carbonate were prepared by ageing, in the presence of urea, a Zr₂(OH)₆SO₄ dispersion containing yttrium nitrate.     

Antimicrobial activity of gentamicin palmitate against high concentrations of <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>

The reduction of implant related infections plays a pivotal role in orthopaedic surgery as an increasing number of people require implants (up to 200,000 per year in the United States (source: Joint Implant Surgery & Research Foundation 2010)). The aim of the current study is to prevent and thus decrease the number of bacterial infections. Both pre and post operative systemic antibiotic treatment and gentamicin containing bone cements (polymethylmethacrylate, PMMA) are commonly used strategies to overcome infections. In this study, the antimicrobial efficacy of gentamicin sulfate loaded bone cement was compared with titan discs coated with a new form of gentamicin, gentamicin palmitate. Adherence prevention, killing rates and killing kinetics were compared in an in vitro model, using Staphylococcus aureus (S. aureus), which together with Staphylococcus epidermidis (S. epidermidis) represents 60% of bacteria found responsible for hip implant infections (An and Friedman, 1996, J Hosp Infect 33(2):93–108). In our experiments gentamicin, which was applied as gentamicin palmitate on the surface of the implants, showed a high efficacy in eliminating bacteria. In contrast to gentamicin sulfate containing bone cements, gentamicin palmitate is released over a shorter period of time thus not inducing antibiotic resistance. Another benefit for clinical application is that it achieves high local levels of active ingredient which fight early infections and minimize toxic side effects. Furthermore, the short term hydrophobic effect of gentamicin palmitate can successfully impede biofilm formation. Thus, the use of self-adhesive antibiotic fatty acid complexes like gentamicin palmitate represents a new option for the anti-infective coating of cementless titan implants.     

Modulation of charge transport properties of reduced graphene oxide by submonolayer physisorption of an organic dye

We have examined the effect of submonolayer coverage of 1-pyrene butyric acid on charge carrier transport in reduced graphene oxide. We have modeled the interaction of 1-pyrene butyric acid molecules with graphene and determined the amount of charge transfer at the interface between the two materials. The effect of 1-pyrene butyric acid as electron acceptor was determined by transfer characteristics measurements on thin film transistors for thick layers. By using time-resolved photocurrent measurements we were able to detect a reduction of electron mobility in reduced graphene oxide for coverage as low as 0.08%.     

PET的等温染色

描述了可替代传统工艺的PET等温染色工艺。这项工艺要求优化的工艺和机械技术以及一种用于等温染色的特殊助剂。相同的方法还可应用于粗纱、长丝和织物。     

EFFECTS OF BORN REPULSION ON PARTICLE DETACHMENT†

The effect of short range Born repulsion on the total interaction energy of unlike spheres has been investigated, with superimposed London-van der Waals and electrostatic contributions. The latter was calculated using the recently derived model based on the two-dimensional Poisson-Boltzmann equation. Specifically, the energy profile as a function of separation is discussed as it relates to the particle detachment process.     

Strive for accuracy—improvement of predictions

Finite-difference approximations to the governing equations of fluid motinos are discussed for viscous three-dimensional flows for Reynolds numbers of several hundred, for three-dimensional incompressible and compressible boundary layers and for inviscid near-sonic supersonic flows. It is shown how the boundary conditions of the problems chosen influence the solutions. If certain conditions to be discussed in the following are not met, neither convergence nor uniqueness of the solution can be guaranteed. Comparison of the predictions described herein with experimental data of the recent literature asserts the validity of the solutions given. The examples chosen include: Viscous flows through biological vessels with bends and bifurcations, formation of Taylor-Görtler vortices in spherical gaps, three-dimensional viscous displacement effect on wings in transonic flow and front and embedded shocks in flow fields with Mach numbers slightly above one.