Assessment of an in vitro whole cigarette smoke exposure system: The Borgwaldt RM20S 8-syringe smoking machine

<p>Abstract</p> <p>Background</p> <p>There have been many recent developments of <it>in vitro </it>cigarette smoke systems closely replicating <it>in vivo </it>exposures. The Borgwaldt RM20S smoking machine (RM20S) enables the serial dilution and delivery of cigarette smoke to exposure chambers for <it>in vitro </it>analyses. In this study we have demonstrated reliability and robustness testing of the RM20S in delivering smoke to <it>in vitro </it>cultures using an in-house designed whole smoke exposure chamber.</p> <p>Results</p> <p>The syringe precision and accuracy of smoke dose generated by the RM20S was assessed using a methane gas standard and resulted in a repeatability error of ≤9%. Differential electrical mobility particle spectrometry (DMS) measured smoke particles generated from reference 3R4F cigarettes at points along the RM20S. 53% ± 5.9% of particles by mass reached the chamber, the remainder deposited in the syringe or connecting tubing and ~16% deposited in the chamber. Spectrofluorometric quantification of particle deposition within chambers indicated a positive correlation between smoke concentration and particle deposition. <it>In vitro </it>air-liquid interface (ALI) cultures (H292 lung epithelial cells), exposed to whole smoke (1:60 dilution (smoke:air, equivalent to ~5 μg/cm²)) demonstrated uniform smoke delivery within the chamber.</p> <p>Conclusions</p> <p>These results suggest this smoke exposure system is a reliable and repeatable method of generating and exposing ALI <it>in vitro </it>cultures to cigarette smoke. This system will enable the evaluation of future tobacco products and individual components of cigarette smoke and may be used as an alternative <it>in vitro </it>tool for evaluating other aerosols and gaseous mixtures such as air pollutants, inhaled pharmaceuticals and cosmetics.</p

Sol–gel prepared bismuth titanate for high temperature ultrasound transducers

Bismuth titanate (BIT) ceramic was prepared via a sol–gel technique and characterised for use as a high temperature ultrasound sensor. Transducers were prepared as both a pressed ceramic disc and a thick film screen printed on a stainless steel shim. Platinum paste was used as an electrode, and oil bath poling at 120 kV cm−1 and 140 °C was done to align dipoles within the samples. The thermal stability of the BIT with regards to the piezoelectric coefficient was examined. Through-thickness ultrasound measurements were made on aluminium and mild steel blocks, and also on a stainless steel pipe at temperatures of up to 230 °C

High temperature thickness measurements using a bismuth titanate piezoelectric transducer

Bismuth titanate Bi4Ti3O12 was prepared through a sol-gel process, characterised and built as a high temperature ultrasound transducer. Platinum electrodes and wires were used throughout for high temperature stability and Pyrogel 100 used as couplant. The piezoelectric coefficient was found to be stable to 550C. Repeatable thickness measurements were made up to 250°C on aluminium and steel test samples using a pulse-echo technique and the efficiency of the transducer studied under thermal cycling