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In breath analysis, ambient air contaminations are ubiquitous and difficult to eliminate. This study was designed to investigate the reduction of ambient air background by a lung wash-out with synthetic air. The reduction of the initial ambient air volatile organic compound (VOC) intensity was investigated in the breath of 20 volunteers inhaling synthetic air via a sealed full face mask in comparison to inhaling ambient air. Over a period of 30 minutes, breath analysis was conducted using ion mobility spectrometry coupled to a multi-capillary column. A total of 68 VOCs were identified for inhaling ambient air or inhaling synthetic air. By treatment with synthetic air, 39 VOCs decreased in intensity, whereas 29 increased in comparison to inhaling ambient air. In total, seven VOCs were significantly reduced (P-value < 0.05). A complete wash-out of VOCs in this setting was not observed, whereby a statistically significant reduction up to 65% as for terpinolene was achieved. Our setting successfully demonstrated a reduction of ambient air contaminations from the airways by a lung wash-out with synthetic air.
Unsaturated polyester resins (UPR) and vinyl ester resins (VER) are among the most commercially important thermosetting matrix materials for composites. Although comparatively low cost, their technological performance is suitable for a wide range of applications, such as fiber-reinforced plastics, artificial marble or onyx, polymer concrete, or gel coats. The main areas of UPR consumption include the wind energy, marine, pipe and tank, transportation, and construction industries. This chapter discusses basic UPR and VER chemistry and technology of manufacturing, and consequent applications. Some important properties and performance characteristics are discussed, such as shrinkage behavior, flame retardance, and property modification by nanoparticles. Also briefly introduced and described are the practical aspects of UPR and VER processing, with special emphasis on the most widely used technological approaches, such as hand and spray layup, resin infusion, resin transfer molding, sheet and bulk molding, pultrusion, winding, and centrifugal casting.
Online measurement of drug concentrations in patient's breath is a promising approach for individualized dosage. A direct transfer from breath- to blood-concentrations is not possible. Measured exhaled concentrations are following the blood-concentration with a delay in non-steady-state situations. Therefore, it is necessary to integrate the breath-concentration into a pharmacological model. Two different approaches for pharmacokinetic modelling are presented. Usually a 3-compartment model is used for pharmacokinetic calculations of blood concentrations. This 3-compartment model is extended with a 2-compartment model based on the first compartment of the 3-compartment model and a new lung compartment. The second approach is to calculate a time delay of changes in the concentration of the first compartment to describe the lung-concentration. Exemplarily both approaches are used for modelling of exhaled propofol. Based on time series of exhaled propofol measurements using an ion-mobility-spectrometer every minute for 346 min a correlation of calculated plasma and the breath concentration was used for modelling to deliver R2 = 0.99 interdependencies. Including the time delay modelling approach the new compartment coefficient ke0lung was calculated to ke0lung = 0.27 min−1 with R2 = 0.96. The described models are not limited to propofol. They could be used for any kind of drugs, which are measurable in patient's breath.
Ethylene terephthalate and ethylene naphthalate oligomers of defined degree of polymerization were synthesized via chemical recycling of the parent polymers. The oligomers were used as defined building blocks for the preparation of novel block-co-polyesters having tailored sequence compositions. The sequence lengths were systematically varied using Design of Experiments. The dispersive surface energy and the specific desorption energy of the co-polymers were determined by inverse gas chromatography. The study shows that polyethylene terephthalate-polyethylene naphthalate (PET-PEN) block-co-polyesters of defined sequence lengths can be prepared. Furthermore, the specific and dispersive surface energies of the obtained block-co-polyesters showed a linear dependence on the oligomer molecular weight and it was possible to regulate and control their interfacial properties. In contrast, with the corresponding random-block-co-polyesters no such dependence was found. The synthesized block-co-polyesters could be used as polymeric modifying agents for stabilizing PET-PEN polymer blends.
The surface properties of human meibomian lipids (MGS), the major constituent of the tear film (TF) lipid layer, are of key importance for TF stability. The dynamic interfacial properties of films by MGS from normal eyes (nMGS) and eyes with meibomian gland dysfunction (dMGS) were studied using a Langmuir surface balance. The behavior of the samples during dynamic area changes was evaluated by surface pressure–area isotherms and isocycles. The surface dilatational rheology of the films was examined in the frequency range 10−5 to 1 Hz by the stress-relaxation method. A significant difference was found, with dMGS showing slow viscosity-dominated relaxation at 10−4 to 10−3 Hz, whereas nMGS remained predominantly elastic over the whole range. A Cole–Cole plot revealed two characteristic processes contributing to the relaxation, fast (on the scale of characteristic time τ < 5 s) and slow (τ > 100 s), the latter prevailing in dMGS films. Brewster angle microscopy revealed better spreading of nMGS at the air–water interface, whereas dMGS layers were non-uniform and patchy. The distinctions in the interfacial properties of the films in vitro correlated with the accelerated degradation of meibum layer pattern at the air–tear interface and with the decreased stability of TF in vivo. These results, and also recent findings on the modest capability of meibum to suppress the evaporation of the aqueous subphase, suggest the need for a re-evaluation of the role of MGS. The probable key function of meibomian lipids might be to form viscoelastic films capable of opposing dilation of the air–tear interface. The impact of temperature on the meibum surface properties is discussed in terms of its possible effect on the normal structure of the film.
Poly(dimethylsiloxane) can be covalently coated with ultrathin NCO-sP(EO-stat-PO) hydrogel layers which permit covalent binding of cell adhesive moieties, while minimizing unspecific cell adhesion on non-functionalized areas. We applied long term uniaxial cyclic tensile strain (CTS) and revealed (a) the preservation of protein and cell-repellent properties of the NCO-sP(EO-stat-PO) coating and (b) the stability and bioactivity of a covalently bound fibronectin (FN) line pattern. We studied the adhesion of human dermal fibroblast (HDFs) on non-modified NCO-sP(EO-stat-PO) coatings and on the FN. HDFs adhered to FN and oriented their cell bodies and actin fibers along the FN lines independently of the direction of CTS. This mechanical long term stability of the bioactive, patterned surface allows unraveling biomechanical stimuli for cellular signaling and behavior to understand physiological and pathological cell phenomenon. Additionally, it allows for the application in wound healing assays, tissue engineering, and implant development demanding spatial control over specific cell adhesion.
Silicones
(2014)
Silicones are found in a variety of applications with requirements that range from long life at elevated temperatures to fluidity at low temperatures. This chapter first considers silicone elastomers and their application in room temperature vulcanizing (RTV) and heat curing systems (HTV). Also, new technologies for UV curing are introduced. Coverage of RTVs includes both one-component and two-component systems and the different cure chemistries of each, and is followed by a separate discussion of silicone laminates. Due to the high importance of silicone fluids, they are also discussed. Fluids include polishes, release agents, surfactants, and dielectric fluids.
Children undergoing systemic chemotherapy often suffer from severe immunosuppression usually associated to severe neutropenia (neutrophils < 0.5 x 109/l). Clinical courses during those periods range from asymptomatic to septic general conditions. Development of septic symptoms can be very fast and life-threatening. Swift detection of risk factors in those patients is therefore needed. So far no early, rapid and reliable marker or tool exists. Ion-Mobility-Spectrometry coupled with a Multi-Capillary-Column (IMS-MCC) can analyze more than 600 volatile components from exhaled air within a few minutes and hence is a potential, rapid detection-tool. As a proof of concept we measured the exhaled breath of 11 patients with neutropenia and 10 healthy controls ranging from 3 to 18 years of age at the time of measurement. Ten milliliters breath samples were taken at the outpatient clinic and analyzed with an onsite IMS-MCC (BreathDiscovery, B&S Analytik, Dortmund, Germany). Dead-space-volume was adapted to two groups (small 250 ml, large 500 ml). Interestingly 59 differing peaks were measured. Eleven were significantly different (p ≤ 0.05), three of which highly significant (p ≤ 0.01) in Mann-Whitney-Rank-Sum-testing. The corresponding analytes used in the decision tree are 2-Propanol, D-Limonene and Acetone. The analytes with the lowest rank sum identified are 2-Hexanone, Iso-Propylamine and 1-Butanol. Eventually we were able to show a three-step-decision-tree, which discerns the 21 samples except one from each group. Sensitivity was 90 % and specificity was 91 %. Naturally these findings need further confirmation within a bigger population. Our pilot-study proves that Ion-Mobility-Spectrometry coupled with a Multi-Capillary-Column is a feasible rapid diagnostic tool in the setting of a pediatric oncology out-patient clinic for patients 3 years and older. Our first results furthermore encourage additional analysis as to whether patients at risk for septic events during immunosuppression can be diagnosed in advance by rapidly assessing risk factors such as Neutropenia in exhaled breath.
Several diseases occur due to asbestos exposure. Until today, asbestos predicted mortality and morbidity will increase because of the long latency period. Actually, the methods to investigate asbestos related disease are mostly invasive. Therefore, the aim of the present paper was to investigate, whether signals in human breath could be correlated to Asbestos related lung diseases using a multi-capillary column (MCC) connected to an ion mobility spectrometer (IMS) as non-invasive method. Here, the breath samples of 10 mL of 25 patients suffering from asbestos related diseases. This group includes patients with asbestos related pleural thickening with and without pulmonary fibrosis. Twelve healthy persons constitute the control group and the breath samples are compared with those of the BK4103 patients. In total 83 peaks are found in the IMS-Chromatogram. A discrimination was possible with p-values <0.001 for two peaks (99.9 %), <0.01 (99 %) for 5 peaks and <0.05 (95 %) for 17 peaks. The most discrimination peaks alpha pinene and 4-ethyltoluol were identified among some others with lower p-values. The corresponding Box-and-Whisker-Plots comparing both groups are presented. In addition, a decision tree including all peaks was created that shows a differentiation with alpha pinene between BK4103 (pleural plaques group) and the control group. In addition, the sensitivity was calculated to 96 %, specificity was 50 %, positive and negative predictive values were 80 % and 86 %. Ion mobility spectrometry was introduced as non-invasive method to separate both groups Asbestos related and healthy. Naturally, the findings need further confirmation on larger population groups, but encourage further investigations, too.
Processing
(2014)
In this chapter, some relevant aspects and illustrative examples of online monitoring tools as the basis for process control in the manufacturing and processing of thermosetting resins are briefly discussed. In principle, any chemical or physical information made accessible by sensors can be used for online monitoring of resin formation, resin location in the mold, and resin cure. For instance, changes in the flow properties of the reaction mixture are often routinely recorded in dependence of the reaction time during resin synthesis as a measure for the degree of conversion of raw materials into macromolecules or oligomers by applying rheometry in an in-process environment. Typically, a small sample of the reaction mixture is by-passed, subjected to rheological measurement, and re-introduced into the bulk reactor. In a similar way, pH measurements, turbidimetric measurements, or other analyses are performed. Although rheometry may not always be suitable for following resin cure (especially in cases where there is a very rapid increase in viscosity after initiation of the cure), [1] naturally, the method can in principle also be used in the subsequent processing of the thermosets, for instance in the curing of wood glue applied to wood specimen [2]. Similarly, pH changes during thermoset curing can be followed. Hence, an encyclopedic and comprehensive approach to present process control methods would systematically proceed according to the involved physical measurement principle. However, since only a very Brief sketch of means for monitoring thermoset processing can be given here, only a small, personally biased selection of important methods and application examples is addressed in the following sections. These examples hopefully illustrate some of the general strategies and solutions to problems that are typically encountered when processing thermosets.