Thermo Systems Incorporated

Time-of-flight aerosol beam spectrometry was first described by Dahneke in 1973 [139]. A commercial instrument, the Aerosizer, [140] was developed by Amherst Process Instruments Inc. which is now a division of Thermo Systems Inc.The TSI Model 3603 replaces the Aerosizer. 

This technique has been extended by inclusion of a pulsed ionization laser to vaporize the particles after their size has been determined by aerodynamic time of flight. This causes the particle to vaporize and the resulting fragments are partly ionized. Positive ions are accelerated into the flight tube of a mass spectrometer where their chemical composition is determined [141] 

TSI Model 3800 Time-of-Flight Mass Spectrometerwas developed in cooperation with the University of California as the first single airborne particle mass spectrometer to be offered commercially. It uses an aerodynamic sizing technique to size individual particles in real time. It then desorbs and ionizes the particle for chemical analysis in a bi-polar, time-of-flight mass spectrometer. It operates in the 0.3 to 3 pm with an optional disperser to extend the range to 10 pm. The instrument can save positive and negative mass spectra at a rate up to 10 particles per second [142]. 

TSI Aerodynamic Particle Sizer APS 335counts and sizes airborne solids and non-volatile liquids at number concentrations up to 600 particles 

TSI Aerodynamic particle size spectrometer model 3327provides two measurements, aerodynamie diameter and light-scattering intensity, in the size range 0.5 to 20 pm. The generation of paired data makes the instrument of partieular interest to aerosol scientists. 

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Blend systems with significantly improved thermo-oxidative performance can be achieved through incorporation of carefully designed polyimide molecules. As shown in Table 1, a copolyimide containing the sulfone and 6F moieties which exhibits a Tg above 300 °C (see Fig. 5), as well as extraordinary short-term thermo-oxidative stability can be synthesized. 

In order achieve the demands of expanded applications, new additives for surface modifications were developed. These additives are often fluoro compounds [13], sometimes fluoroalkylsilanes [14], and in many cases alkylsilanes. When these additives are incorporated into a polymer matrix, the extremely valuable properties of these chemicals like chemical inertness, thermo-oxidative stability, and resistance against water can be transferred to the whole polymer system. This incorporation can either be achieved by chemical bonding to the resin matrix or by formation of an interpenetrating polymer network. 

S-2500 Hitachi Thermo NORAN equipped with an energy-dispersive X-ray spectrometer and prior to the SEM studies the surface was gold or carbon-coated using a vacuum evaporator Edwards Auto 306. A Perkin Elmer System One spectrometer was used to obtain the FTIR spectrums while a Goniometre C diffractometer, incorporating a cobalt radiation (k = 1.78892 A) was used to obtain the X-ray diffraction patterns. 

In the FIA system, peristaltic pnimp (ISMATEC ITC, Switzerland) 0.50 mm i.d. PFTE tubing was used to propel the samples and reagent solutions. Samples were injected into the carrier stream by a 7125 model stainless steel high pressure Rheodyne injection valve provided with a 20 )xL loop. The absorbance of the coloured complex formed (Xmax 415 nm) was measured with a UV-Visible spectrophotometer equip>p)ed with a flow-through micro cell (Spectra SYSTEM UV 3000 HR, Thermo Separation Products, USA), and connected to a compniter incorporated with a PCI000 software programme. 

The use of the internal standard minimizes the effect of changes in instrnmental parameters and can result in better accuracy and precision. Newer Raman systems snch as the Thermo Scientific DXR series incorporate a laser power regulator that delivers reproducible laser power to the sample and compensates for laser aging and variability, minimizing the need for internal standards. 

Considering the system without filler, even 7 mol% of epoxy groups in the main chain lead to considerable variation in the Tg and maximum value of G". This result underlines the thermo-analytical variations considering dynamic changes in the chains. The incorporation of precipitated silica in both polymers leads to small changes in the glass transition temperature and, at the same time, causes remarkably increase of the maximum G" value. A more detailed date evaluation shows that by... 

The common feature of thermo-responsive potymers are the coexistence of hydrophobic (e.g., methyl, ethyl, propyl) and hydrophilic (e.g., amide, carboxyl) groups in one macromolecular network. The polymers with an LCST are mostly used in drug delivery systems. The hydrophobic and the hydrophilic moieties in the molecular chain of a temperature-responsive polymer define its LCST. Hydrophilic monomers make the LCST increase and even disappear, and hydrophobic ones cause the LCST to decrease. Thus, a proper ratio of hydrophobic or hydrophilic moieties can be incorporated in order to get a suitable LCST. The adjustment of LCST to approximately body temperature is essential especially in the case of drug delivery applications [15, 18-20]. The transition temperature of the polymer can be modified using certain additives such as surfactant, salt concentration, or co-solvents. Surfactants act as amphiphiles when added into the pol5mieric solution modifies its hydrophilic-hydrophobic balance and further its transition temperature [21]. 

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