Throughput in tuberculosis drug discovery was extremely limited prior to the introduction of microplate-based susceptibility assays. The 96-well Microplate Alamar Blue Assay (MABA) allows for the quantitative determination of drug susceptibility against any strain of replicating Mycobacterium tuberculosis to be completed within a week at minimal cost. The Low-Oxygen Recovery Assay (LORA) uses a recombinant M. tuberculosis expressing luciferase and provides results of drug activity against non-replicating M. tuberculosis surviving under hypoxic conditions. Determining activity against non-replicating M. tuberculosis is an important factor when developing drug candidates against M. tuberculosis. Here we describe a step-by-step procedure for both the MABA and LORA.
A novel method for increasing the transparency of an anodic aluminum oxide film on glass is demonstrated. The residual aluminum layer, which limits the transparency of the porous aluminum oxide film, was fully converted to its oxide by the ion-drift process. The transmittance of the film was improved more than 20% over the visible-near infrared range and was similar to that of a glass substrate. This ion-drift process also improved the adhesion of the anodic alumina film to the glass substrate.Nanoporous anodic aluminum oxide films are of great interest in various applications because of their stability and unique structural and optical properties. 1,2 As their applications grow, specific requirements for the preparation of anodic alumina film are increased. For example, a transparent porous anodic alumina film on glass is highly desired in optical and optoelectronic devices.The anodization of an aluminum film on an insulating substrate always leaves an unoxidized aluminum metal and results in a semitransparent ͑dark colored͒ anodic alumina film. Miney et al. estimate the thickness of the unoxidized aluminum layer to be ϳ1.2 nm from an ellipsometric study. 3 Although the remaining aluminum layer is very thin, the transmittance of the anodic alumina film rarely exceeds 60%, as aluminum is one of the most optically dense metals.Nearly all the previous work on complete anodization of aluminum films on insulating substrates was done by inserting a conducting medium between the substrate and the aluminum layer. Very thin layers of valve metals, such as titanium, 4 niobium, 5 and tantalum, 6,7 were introduced for this purpose. However, this produces a bulge of valve metal oxide and leaves the unoxidized layer that also reduces the transmittance. Chu et al. utilizes a transparent indium-tin oxide ͑ITO͒ layer as a conducting medium and the transmittance of the anodic alumina film was nearly equivalent to that of ITO glass. 8 It was found to be very difficult to prepare a uniform, large area anodic alumina film, however. Temperature, electric field, and the thickness of aluminum and conducting films must be uniform over entire substrate and the anodization process must be critically controlled. Otherwise, nonuniform anodization will be obtained. Also, gas evolution and sparking destroy the alumina film as the anodization reaches the Al-conducting medium interface. In addition, the adhesion between the alumina film and substrate is poor if an aluminum layer on a conducting medium is anodized. 9 This lack of adhesion may be beneficial for some purposes such as a nano-pattern transfer and preparation of free standing films, but it is highly undesirable in most applications.In other contexts, anodic bonding is widely used in microsystem technology to join glass and silicon. 10 The basic mechanism is the thermal activation of alkali and oxygen ions and their drift in the electric field applied during bonding. 11,12 This generates a high electric field within the depletion region and forms homogeneous and reliable bonds through...
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