ABSTRACT
Multichannel (multicolor) imaging has become a powerful technique in biology research for performing in vivo neuronal calcium imaging, colocalization of fluorescent labels, non-invasive pH measurement, and other procedures. We describe a novel add-on approach for simultaneous multichannel optical microscopy based on simple wedge prisms. Our device requires no alignment and is simple, robust, user-friendly, and less expensive than current commercial instruments based on switchable filters or dual-view strategies. Point spread function measurements and simulations in Zemax indicate a reduction in resolution in the direction orthogonal to the wedge interface and in the axial direction, without introducing aberration. These effects depend on the objective utilized and are most significant near the periphery of the field of view. We tested a two-channel device on C. elegans neurons in vivo and demonstrated comparable signals to a conventional dual-view instrument. We also tested a four-channel device on fixed chick embryo Brainbow samples and identified individual neurons by their spectra without extensive image postprocessing. Therefore, we believe that this technology has the potential for broad use in microscopy.
Subject(s)
Caenorhabditis elegans/cytology , Microscopy/methods , Neurons/metabolism , Optical Imaging/methods , Animals , Calcium-Binding Proteins/metabolism , Chick Embryo , Fluorescent Dyes/metabolism , Green Fluorescent Proteins/metabolism , Luminescent Proteins/metabolism , Microscopy/instrumentation , Microscopy, Fluorescence/instrumentation , Microscopy, Fluorescence/methods , Optical Imaging/instrumentation , Red Fluorescent ProteinABSTRACT
Identifying and implementing techniques for carbon management has become an important endeavor in the mitigation of global climate change. Two important techniques being pursued are geologic and terrestrial carbon sequestration. With regard to terrestrial sequestration, in order to accurately monitor changes in soil carbon potentially induced by sequestration practices, rapid, cost-effective, and accurate measurements must be developed. Spark-induced breakdown spectroscopy (SIBS) has the potential to be used as a field-deployable method to monitor changes in the concentration of carbon in soil. SIBS spectra in the 248 nm region of eight soils were collected, and the neutral carbon line at 247.85 nm was compared to total carbon concentration determined by standard dry combustion techniques. Additionally, Fe and Si emission lines were evaluated in a multivariate statistical model to evaluate their impacts on the model's predictive power for total carbon concentrations. The preliminary results indicate that SIBS is a viable method to quantify total carbon levels in soils, obtaining a correlation of (R(2)=0.972) between measured and predicated carbon in soils. These results show that multivariate analysis can be used to construct a calibration model for SIBS soil spectra.
Subject(s)
Carbon/analysis , Multivariate Analysis , Soil/analysis , Spectrum Analysis/methods , Iron/analysis , Silicon/analysisABSTRACT
Spark-induced breakdown spectroscopy (SIBS) is a recently developed atomic-fluorescene-based analytical technique that is analogous to laser-induced breakdown spectroscopy. SIBS, however, uses an electrical plasma generation method on nonconductive samples instead of a focused laser beam. Here we describe the basic characteristics of SIBS and its application to the field-screening analysis of soil, using a standard addition analytical approach. Detection limits of approximately 25 mg/kg have been seen for lead, chromium, barium, mercury, and cadmium. A variety of soils have been tested, some cocontaminated with organic material and uranium (238U).
