Search

Rapid screening of tuberculosis by evaluation of associated volatile organic biomarkers in breath is a promising technology that is significantly faster and more convenient than traditional sputum culture tests. Methyl nicotinate (MN) and methyl p-anisate (MPA) have been isolated as potential biomarkers for mycobacterium tuberculosis and have been found in the breath of patients with active pulmonary tuberculosis. A novel approach to detection of these biomarkers in liquid droplets (e.g. from breath condensate) using inexpensive screen-printed electrodes is presented. Previous modelling studies suggest that these biomarkers complex with certain transition metals of particular valence state. This interaction can be exploited by mixing the biomarker sample into an electroactive solution (EAS) containing the functional metal ion and observing the change electrochemically. The study focuses on low biomarker concentrations, determined to be clinically relevant based on preliminary GC-MS studies of the levels found in patient breath. It was found that both the cyclic voltammogram and square wave voltammogram of copper(II) change significantly when as little as 0.1 mM MN is added to the solution, with analysis times of less than 2 min. Copper(II) exhibits three separate peaks during square wave voltammetry. The location and area of each peak are affected differently as the concentration of MN increases, suggesting a reaction with specific oxidation states of the metal. In this way, a "fingerprint" method can be used to identify biomarkers once their known interaction is established.

In this work, 3D-printed Ti6Al4V structures are used as substrates to synthesize TiO2 nanotube arrays by electrochemical anodization. These nanostructured materials are used as supports for bimetallic FeCo catalysts in Fischer–Tropsch synthesis to produce hydrocarbons from syngas. These structures are annealed to assess the influence of phase transformations in the development of TiO2 nanotubes. Field-emission scanning electron microscopy (FESEM) images of the untreated structures reveal needle-like formations in their microstructure, characteristic of Ti in its α′-phase resulting from the 3D printing process. X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDXS) are used to compare the specimens before and after annealing. The results suggest that annealing at 850 °C before anodization introduces an undesirable oxide layer, impeding the formation of TiO2 nanotubes. This phenomenon is attributed to the complex crystallographic features of the phases formed during annealing, specifically Ti-β and TiO2-rutile, which prevent fluoride ions in the electrolyte from penetrating the structure. The results suggest that the optimal synthesis process is a two-step electrochemical treatment followed by low-temperature annealing at 450 °C. This sequence produces a desirable crystalline morphology due to the phase transformation from TiO2-rutile into TiO2-anatase, as shown by XRD. EDXS data shows that the fluorine content from residual ions from the anodizing solution is significantly reduced after annealing. Fischer–Tropsch catalysts are synthesized using a FeCo (2.0 wt%) active phase on the optimized TiO2 nanotube arrays and tested in a packed-bed reactor. These materials display catalytic activity, comparable to nanoparticulate TiO2 supported catalysts, with considerable selectivity for lighter hydrocarbons. [ABSTRACT FROM AUTHOR]

In this work, the fabrication of microstencils for patterning on unconventional substrates was demonstrated. Stencil feature sizes ranging from 6 to 370 [micro]m with aspect ratios (stencil feature height : width) in the range of 0.5 : 1 to 15 : 1 were fabricated using ICP etching of silicon. The stenciling process was demonstrated for the deposition of metals (Ti/Au) and dielectrics (silicon dioxide) onto silicon, glass, and polymer based substrates for microfluidic system development. The results demonstrated some dependency of the deposition rate on the stencil feature size and aspect ratio. Results from adhesion studies showed excellent adhesion on all substrates with the exception of PMMA. Index Terms--Metallization, microstenciling, microsystems, thin-film deposition.

Screening of colorectal cancer is crucial for early stage diagnosis and treatment. Detection of volatile organic compounds (VOCs) of the metabolome present in exhaled breath is a promising approach to screen colorectal cancer (CRC). Various forms of volatile organic compounds (VOCs) that show the definitive signature for the different diseases including cancers are present in exhale breathe. Among all the reported CRC VOCs, cyclohexane, methylcyclohexane, 1,3-dimethyl- benzene and decanal are identified as the prominent ones that can be used as the signature for CRC screening. In the present investigation, detection of the four prominent VOCs related to CRC is explored using functionalized titania nanotubular arrays (TNAs)-based sensor. These signature biomarkers are shown to be detected using nickel-functionalized TNA as an electrochemical sensor. The sensing mechanism is based on the electrochemical interaction of nickel-functionalized nanotubes with signature biomarkers. A detailed mechanism of the sensor response is also presented. [ABSTRACT FROM AUTHOR]

Morphological studies of TiO2-Al2O3 and TiO2-Ta2O5 nanocomposite nanotubes synthesised on silicon substrates are presented here. Nanocomposite Ti-Al and Ti-Ta thin films were deposited on silicon substrates via simultaneous multi-target sputtering of Ti and Al targets or Ti and Ta targets, followed by anodisation in a fluorinated electrolyte. By increasing the Al or Ta concentration in the sputtered films, the morphology of the anodised films is changed from tubular oxides (with ripples on the outer walls) to well-aligned porous oxides (smooth walls, near zero gap between walls). By increasing the concentrations of Ta, formation of random Y-branched porous oxides in the anodised films is demonstrated. These nanotubes were synthesised on a planar substrates making them suitable for integrated circuits. [ABSTRACT FROM AUTHOR]