The Thermal Balance of Substrates During Plasma Processing

In this paper an example is given for measurement and calculation of the energy influx towards a substrate during plasma processing in a supersonic reactor. From the results the energy transfer coefficients are obtained for several pressures. Also the evolution of the profile of the temperature is presented.     

Photoluminescence spectra of self-assembling helical supramolecular assemblies: a theoretical study

The reversible assembly of helical supramolecular polymers of chiral molecular building blocks is known to be governed by the interplay between mass action and the competition between weakly and strongly bound states of these building blocks. The highly co-operative transition from free monomers at high temperatures to long helical aggregates at low temperatures can be monitored by photoluminescence spectroscopy that probes the energetically lowest-lying optical excitations in the assemblies. In order to provide the interpretation of obtained spectroscopic data with a firm theoretical basis, we present a comprehensive model that combines a statistical theory of the equilibrium polymerization with a quantum-mechanical theory that not only accounts for the conformational properties of the assemblies but also describes the impact of correlated energetic disorder stemming from deformations within the chromophores and their interaction with solvent molecules. The theoretical predictions are compared to fluorescence spectra of chiral oligo(p-phenylene-vinylene) molecules in the solvent dodecane and we find them to qualitatively describe the red-shift of the main fluorescence peak and its decreasing intensity upon aggregation.     

In Situ Synchrotron X-ray Diffraction Studies of the Mechanochemical Synthesis of ZnS from its Elements

Mechanochemistry, as a synthesis tool for inorganic materials, became an ever-growing field in material chemistry. The direct energy transfer by collision of the educts with the milling media gives the possibility to design environmental-friendly reactions. Nevertheless, the underlying process of energy transfer and hence the kinetics of mechanosynthesis remain unclear. Herein, we present in situ synchrotron X-ray diffraction studies coupled with pressure measurements performed during the formation of ZnS and the subsequent phase transition (PT) from the hexagonal to the cubic modification. Milling Zn and S₈ results in the sublimation of S₈, observed by a sudden pressure increase. Simultaneously, the hexagonal metastable ZnS-modification (wurtzite) forms. Via detection of the pressure maximum, the exact start of the wurtzite formation can be determined. Immediately after the formation of wurtzite, the structural PT to the thermodynamic stable cubic modification sphalerite takes place. This PT can be described by the Prout-Tompkins equation for autocatalytic reactions, similar to thermally induced PT in sulfur vapor at high temperatures (T>1133 K). The increase in the reactivity of the wurtzite formation is explained by the reaction in sulfur vapor and the induction of defect structures by the collisions with the milling media.     

Designing man–machine interactions for mobile clinical systems: MET triage support using Palm handhelds

The Mobile Emergency Triage (MET) system is a clinical triage support system that aids physicians in making triage decisions as to whether a child presenting in the Emergency Department of a hospital with a specific pain complaint should be discharged to a family physician, needs to be admitted for further investigation/observation, or requires an urgent specialist consult. The system’s mobile component is designed to work on handheld computers. This paper presents our experience and discusses our original solutions with regard to designing man–machine interactions for mobile clinical support systems. The specific interactions adopted in the MET design that are discussed in the paper were created in consultation with potential end-users and tested at the Children’s Hospital of Eastern Ontario in Ottawa.     

Determination of electron density and energy influx in a hollow cathode glow discharge used for powder modification

The electron density and energy influx in an argon hollow cathode glow discharge were determined to obtain adequate parameters for subsequent surface modification of low density polyethylene (LDPE) powder to change the wettability. The electron density was studied by Langmuir probe measurement in dependence on process gas pressure and hollow cathode material. Besides the determination of the rate of increasing electron density with input power an optimal experimental pressure was determined. The energy influx was studied by thermal probe measurements in dependence on process gas pressure, bias voltage, axial position and hollow cathode material. Inside the hollow cathode the energy influx is nearly constant along the whole cathode length. With increasing pressure the energy influx decreased. At biased thermal probe the energy influx was observed to decrease up to the floating potential and beyond it increases with increasing voltage. Using different hollow cathode materials the electron density as well as the energy influx reach higher values for aluminum than for copper and stainless steel.     

Quantitative MR imaging of targeted SPIO particles on the cell surface and comparison to flow cytometry

Purpose

To detect anti-CEACAM5 targeted superparamagnetic iron oxide (SPIO) particles in vitro on the cell surface by quantitative magnetic resonance (MR) imaging and to compare with flow cytometry.

Materials and Methods

The monoclonal mouse antibody T84.1 and an appropriate IgG isotype antibody were conjugated to dextran-coated SPIO particles. HT29 cells expressing carcinoembryonic antigen (CEACAM5) were treated with antibody-conjugated SPIO particles. Purified cell samples were examined on a 3.0-T MR scanner using a multi-echo spin-echo sequence for MR relaxometry. Aliquots of the cell samples were further treated with a fluorescein isothiocyanate (FITC) anti-dextran antibody and an Alexa Fluor 488 anti-mouse antibody for the corresponding flow cytometry.

Results

MR relaxometry revealed a dose-dependent binding of T84.1-conjugated SPIO particles with a positive correlation between R₂ relaxation rate of cell samples and SPIO particle concentration during incubation (r=0.993, P<.01). Positive correlations were also observed between R₂ relaxation rate and flow cytometry (geometric mean) with both fluorescent antibodies (r=0.972 and r=0.953, both P<.01), respectively.

Conclusion

The study revealed the feasibility of quantitative MR imaging of targeted SPIO particles on the cell surface comparable to flow cytometry.     

180° -turns in integrated optics

Integrated optic devices, such as directional couplers, typically have a length to width ratio of 1:1000. Therefore economical use of quadratic substrate areas requires 180° wave guide turns to cover the whole substrate with a complex circuit in a zick-zack manner. For 180° -turns only curved guides have been considered. Radii of > 1 cm are necessary to avoid loss, and therefore are useless. A new concept for 180° -turns is proposed consisting of a halved 3 stage Δβ-reversal coupler with mirrors at one end. It is demonstrated that these 180° -turns may be fabricated providing high efficiency.     

Correlation of solute retention in gas chromatography with properties of the anion for tetra-n-butylammonium salts

Variations in the molar retention volume of organic solutes on thirteen tetra-n-butyl-ammonium salts with a common liquid temperature range are correlated with the properties of the anion. The anions studied include the chloride, bromide, nitrate, nitrite, methanesulfonate, trifluoromethanesulfonate, ethanesulfonate, 4-toluenesulfonate, sulfamate, thiocyanate, picrate, pentacyanopropenide, and tetra-n-butylborate. The high melting points and poor thermal stabilities of camphorsulfonate, dihydrogenphosphate, hydrogensulfate, and perrhenate precluded their use. The properties of the anions have only smallinfluences on the magnitudes of dispersive, orientative, and proton-donor interactions with the test solutes. Orientative interactions are strong for polar solutes but vary little with anion structure. There was no correlation between the dipole moment of the tetra-n-butylammonium salts and the retention of polar solutes. The structures of the anion do, however, have large influences on the retention of proton-donor solutes. for these solutes, a good correlation was found between molar retention volume and the basicity of the anions, represented by their pK_a values in aqueous solution.