Search results for "silicone"
showing 10 items of 78 documents
Polydimethylsiloxane (silicone rubber) brooch as a personal passive air sampler for semi-volatile organic compounds
2018
Exposure assessments conducted using a personal sampler include the contribution of human activities to exposure that is neglected when using a stationary air sampler. This study evaluated the uptake characteristics and application of the polydimethylsiloxane (PDMS or silicone rubber) brooch as a personal passive air sampler (PPAS) for measuring concentrations of two groups of semi-volatile organic compounds (SVOCs), namely phthalates and organophosphate esters (OPEs), indoors in proximity to the breathing zone. Uptake rates of the PDMS brooch were calibrated against a personal low volume active air sampler (PLV-AAS) co-deployed on each of five study participants working in offices for 8 hs…
EDXRF and TXRF analysis of elemental size distributions and environmental mobility of airborne particles in the city of Riga, Latvia
2004
Airborne particles were investigated in the central part of Riga during October 2000. Mass, black carbon and elemental concentrations of airborne particles were measured on Teflon filters from a dichotomous impactor, which samples fine (<2.5 µm) and coarse (2.5‐10 µm) fractions of particles. In order to obtain more detailed information on the size distributions of different elements, a seven-stage Batelle cascade impactor was used, in which quartz plates treated with silicone grease were utilized as backing for the different stages. Total reflection x-ray fluorescence (TXRF) and energy-dispersive x-ray fluorescence (EDXRF) spectrometry were used for elemental analysis on the quartz plates a…
Enhanced styrene removal in a two-phase partitioning bioreactor operated as a biotrickling filter: Towards full-scale applications
2017
Abstract Styrene vapor abatement was investigated in a two-phase partitioning bioreactor operated as a biotrickling filter (TPPB-BTF). The removal performance of the TPPB-BTF was simultaneously compared with a conventional BTF, which served as a control. Industrial-grade silicone oil was used as the non-aqueous phase in the TPPB-BTF due to its high affinity for styrene. Both bioreactors were operated at styrene inlet concentrations ranging from 55 to 323 mg C m −3 and empty bed residence times (EBRT) of 15–30 s, corresponding to pollutant loading rates of 13–77 g C m −3 h −1 . Both bioreactors exhibited styrene removal efficiencies (REs) higher than 90% at an EBRT of 30 s. Nevertheless, th…
Zum metabolismus von dialkyldithiocarbamaten
1974
Abstract Metabolism dialkyldithiocarbamates. I. Determination of amines using a reaction with isocyanates followed by gas chromatographic identification of the urea derivatives formed. N,N′-Di- and N,N′,N′-trisubstituted areas, formed by the reaction of amines with isocyanates, e.g. tert. -butyl isocyanate or 3-trifluoromethylphenyl isocyanate, are useful derivatives for the gas chromatographic analysis of primary and secondary amines. The separation is carried out at temperatures between 70 and 130° on liquid phases such as silicone OV-101 and silicone OV-17. With nitrogen and electron capture detectors the detection limit is 10 10 g. Trace analysis of simple primary and secondary amines i…
Effective hydrostatic limits of pressure media for high‐pressure crystallographic studies
2007
The behavior of a number of commonly used pressure media, including nitrogen, argon, 2-propanol, a 4:1 methanol–ethanol mixture, glycerol and various grades of silicone oil, has been examined by measuring the X-ray diffraction maxima from quartz single crystals loaded in a diamond-anvil cell with each of these pressure media in turn. In all cases, the onset of non-hydrostatic stresses within the medium is detectable as the broadening of the rocking curves of X-ray diffraction peaks from the single crystals. The onset of broadening of the rocking curves of quartz is detected at ∼9.8 GPa in a 4:1 mixture of methanol and ethanol and at ∼4.2 GPa in 2-propanol, essentially at the same pressures …
Synthesis of Liquid-Crystalline Colloids in Nonpolar Media and their Manipulation in Electric Fields
2009
The first synthesis of anisotropic liquid-crystalline colloids in silicone oil by a direct (radical) polymerization of a monomer in THF/silicone oil mixtures with the help of siloxane containing stabilizers is described. The size of the colloids is in the lower μm range and can be adjusted by varying the mixture. The resulting colloids show a bipolar director configuration if they are small (<1.5 μm) and a radial configuration if they are larger. The colloids are sterically stabilized, and, due to the nonpolarity of the solvent, the disturbing effects of migrating ions are excluded and experiments in the electric field can be conducted. Both line formation in DC fields and a periodic switch…
Oxygen Transmissibility of Piggyback Systems With Conventional Soft and Silicone Hydrogel Contact Lenses
2006
To investigate the apparent oxygen transmissibility of various piggyback systems using conventional and silicone hydrogel soft contact lenses of different water content and permeability, rigid poly(methyl methacrylate), and rigid gas-permeable lenses of medium, high, and ultrahigh oxygen permeability. The aim of the study was to establish which material (rigid or hydrogel) is more representative of the resulting oxygen performance of piggyback systems. METHODS: The apparent oxygen transmissibility of 66 piggyback systems was measured with an electrochemical method. Eighteen of these combinations involved the use of silicone hydrogel contact lenses currently available. One hyperpermeable rig…
Biotrickling filter modeling for styrene abatement. Part 2: Simulating a two-phase partitioning bioreactor.
2017
Abstract A dynamic model describing styrene abatement was developed for a two-phase partitioning bioreactor operated as a biotrickling filter (TPPB-BTF). The model was built as a coupled set of two different systems of partial differential equations depending on whether an irrigation or a non-irrigation period was simulated. The maximum growth rate was previously calibrated from a conventional BTF treating styrene (Part 1). The model was extended to simulate the TPPB-BTF based on the hypothesis that the main change associated with the non-aqueous phase is the modification of the pollutant properties in the liquid phase. The three phases considered were gas, a water–silicone liquid mixture, …
Material properties of various intraocular lenses in an experimental study.
2002
<i>Introduction:</i> With the recent introduction of small-incision cataract surgery, requirements for intraocular lens (IOL) flexibility, strength and hydrophilicity have rapidly evolved. The IOL surface, however, remains a critical factor influencing uveal biocompatibility. <i>Purpose:</i> To objectively quantify factors of material properties of various IOLs using contact angle measurements, differential scanning calorimetry, dynamic-mechanical measurements and scanning electron microscopy. <i>Material and Methods:</i> In our study, 17 currently available IOLs were investigated using contact angle measurements to assess hydrophilicity and biocompatibil…
Microscale Marangoni actuation: All-optical and all-electrical methods
2006
We present experimental results from an all-optical microfluidic platform that may be complimented by a thin film all-electrical network. Using these configurations we have studied the microfluidic convective flow systems of silicone oil, glycerol, and 1,3,5-trinitrotoluene on open surfaces through the production of surface tension gradients derived from thermal gradients. We show that sufficient localized thermal variation can be created utilizing surface plasmons and/or engaging individually addressable resistive thermal elements. Both studies manipulate fluids via Marangoni forces, each having their unique exploitable advantages. Surface plasmon excitation in metal foils are the driving …