Detection of urological cancers by the signature of organic volatile compounds in urine, from dogs to electronic noses.

PURPOSE OF REVIEW: Urine volatile organic compound (VOC) testing for early detection of urological cancers is a minimally invasive and promising method. The objective of this review was to present the results of recently published work on this subject. RECENT FINDINGS: Organic volatile compounds are produced through oxidative stress and peroxidation of cell membranes, and they are eliminated through feces, urine, and sweat. Studies looking for VOCs in urine for the diagnosis of urological cancers have mostly focused on bladder and prostate cancers. However, the number of patients included in the studies was small. The electronic nose was the most widely used means of detecting VOCs in urine for the detection of urological cancers. MOS sensors and pattern recognition machine learning were more used for the composition of electronic noses. Early detection of urological cancers by detection of VOCs in urine is a method with encouraging results with sensitivities ranging from 27 to 100% and specificities ranging from 72 to 94%. SUMMARY: The olfactory signature of urine from patients with urological cancers is a promising biomarker for the early diagnosis of urological cancers. The electronic nose with its ability to recognize complex odors is an excellent alterative to canine diagnosis and analytical techniques. Nevertheless, additional research improving the technology of Enoses and the methodology of the studies is necessary for its implementation in daily clinical practice.

Local dynamic mechanical analysis.

While new materials with tailored properties appear every day, the need of appropriate characterization tools is still an important concern. Analyses of thin films on thick substrate are often highly influenced by the substrate properties. A dynamical nanoindentation system has been designed and built through the integration of a nanoindenter head equipped with capacitive displacement sensing, scanning probe microscope with related XYZ scanning electronics and an additional transducer for sample actuation. Our Local-Dynamic Mechanical Analysis (L-DMA) setup allows for both, tip and sample modulation mode what somehow contrasts with commercially available systems. This issue allows for direct comparison between both techniques and therefore for consistent quantitative mechanical measurements. The system offers two distinctive measurement techniques, local mechanical spectroscopy and mechanical imaging modes. Bulk materials as well as thin films of ceramics and polymers have been used for testing and validating the setup. The instrument has been modeled in sample modulation mode and experimental results obtained for different materials were compared with simulation data.

Geometry of Chemical Beam Vapor Deposition System for Efficient Combinatorial Investigations of Thin Oxide Films: Deposited Film Properties versus Precursor Flow Simulations.

An innovative deposition system has been developed to construct complex material thin films from single-element precursors by chemical beam vapor deposition (CBVD). It relies on well distributed punctual sources that emit individually controlled precursor beams toward the substrate under high vacuum conditions combined with well designed cryo-panel surfaces that avoid secondary precursor sources. In this configuration the impinging flows of all precursors can be calculated at any substrate point considering the controlled angular distribution of the emitted beams and the ballistic trajectory of the molecules. The flow simulation is described in details. The major advantage of the deposition system is its ability to switch between several possible controlled combinatorial configurations, in which the substrate is exposed to a wide range of flow compositions from the different precursors, and a uniform configuration, in which the substrate is exposed to a homogeneous flow, even on large substrates, with high precursor use efficiency. Agreement between calculations and depositions carried out in various system configurations and for single, binary, or ternary oxides in mass transfer limited regime confirms that the distribution of incoming precursors on the substrate follows the theoretical models. Additionally, for some selected precursors and in some selected conditions, almost 100% of the precursor impinging on the substrate is incorporated to the deposit. The results of this work confirm the potentialities of CBVD both as a research tool to investigate efficiently deposition processes and as a fabrication tool to deposit on large surfaces.

Low temperature degradation of a Y-TZP dental ceramic.

Bars of Y-TZP ceramic for dental restorations were subjected to hydrothermal degradation via in vitro exposure to water steam at 140°C for 7 days. X-ray diffraction, atomic force microscopy and scanning electron microscopy techniques were applied to observe and quantify the tetragonal-monoclinic (t-m) phase transformation associated with the process. Nanoindentation was used to assess the ceramic's mechanical properties before and after hydrothermal degradation. Texture associated with martensitic t-m transformation was observed at the grain surface. The t-m transformation followed nucleation-and-growth kinetics, with predominance of the nucleation process. The transformation occurred within a layer of 6 µm below the surface. Mechanical properties deteriorated with hydrothermal degradation, resulting in a 30% reduction of Young's modulus and hardness. A strong correlation was found between the increasing monoclinic fraction and the decline in mechanical response. It was thus concluded that the emergence of the monoclinic phase and the associated microcracking were the most likely causes for the degradation of mechanical properties.