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This paper reports the spatially resolved surface modification of polystyrene (PS) using an atmospheric‐pressure microplasma jet. Treatment of PS surfaces using a microplasma jet with a 100 µm diameter is investigated using contact angle, XPS, AFM and lens epithelial cell (LEC) growth. Microplasma jet treatment creates a defined reduction in contact angle of approximately 60° in a circular pattern with a diameter of 1.5 mm or more. Spatially resolved XPS analysis demonstrates that a reduction in contact angle is related to an increase in O1s peak intensity. AFM confirms that microplasma jet treatment causes no significant change in surface roughness. LECs are confined to a treated area.

A single human oesophageal adenocarcinoma cell (OE33) has been imaged using aperture infrared scanning near-field optical microscopy (IR-SNOM) in transmission and reflection and also by Fourier-transform infrared (FTIR) microspectroscopy in transmission only. This work presents the first images obtained in both transmission and reflection of the same specimen using the aperture IR-SNOM technique. The results have been used to compare the two SNOM modes and also the two techniques, which have complementary capabilities. The SNOM technique necessitates a very stable source and a careful choice of wavelengths, since it is too slow to yield images at the thousands of wavelengths obtained with FTIR. However the SNOM technique is not diffraction limited and with careful fabrication of tips can yield images with high spatial resolution. There is no significant correlation between the SNOM images obtained in transmission and reflection and the correlations between images obtained at different wavelengths vary with the different imaging modes. These results are attributed to the strong dependence of the evanescent wave on both the wavelength and the distance between the tip and the source of the signal within the sample. While both transmission and reflection SNOM images show some correlation with topography this is not a dominant effect. These results indicate that with suitable calibration a combination of reflection and transmission aperture IR-SNOM measurements has the potential to reveal information on the depth distribution of the chemical structure of a specimen.

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A novel machine learning algorithm is shown to accurately discriminate between oral squamous cell carcinoma (OSCC) nodal metastases and surrounding lymphoid tissue on the basis of a single metric, the...