Reverse sampling

Shen Y, LG Stehmeier, G Voordouw (1998) Identification of hydrocarbon-degrading bacteria in soil by reverse sample genome probing. Appl Environ Microbiol 63 637-645. 

Voordouw G, JK Voordouw, RR Karkhoff-Schweiser, PM Eedorak, DWS Westlake (1991) Reverse sample genome probing, a new technique for identification of bacteria in environmental samples by DNA hybridization, and its application to the identification of sulfate-reducing bacteria in oil field samples. Appl Environ Microbiol 57 3070-3078. 

Greene, E. A. Voordouw, G. Analysis of environmental microbial communities by reverse sample genome probing. J. Microbiol. Meth. 2003,53,211-219. 

We propose here to apply the technique to the bounded deconvolution problem. Trial grain positions may be selected at random or by some other process, such as bit-reversed sampling (Allebach, 1981 Deutsch, 1965). The trial solution after t grains have been placed is d. The corresponding objective function may be, but is not limited to, a sum of squares ... 

The reverse sample genome probe procedure has been used to monitor sulfate-reducing bacteria in oil-field samples (Voordouw et al. 1991), further extended to include 16 heterotrophic bacteria (Telang et al. 1997), and has been applied to evaluating the effect of nitrate on an oil-field bacterial community. 

Telang, A.J., S. Ebert, L.M. Focht, D.W. Westlake, G.E. Jenneman, D. Gevertz, and G. Voordouw. 1997. Effect of nitrate injection on the microbial community in an oil field monitored by reverse sample genome probing. Appl. Environ. Microbiol. 63 1785-1793. 

Suzuki H, Tokuda T, Kobajashi K (2002) A disposable intelligent mosquito with a reversible sampling mechanism using the volume-phase transition of a gel. Sens Actual B 83 53-59 Tanaka T (1978) Collapse of gels and critical endpoint. Phys Rev Lett 40 820-823 Tanaka T, Fillmore DJ (1979) Kinetics of swelling of gels. J Chem Phys 70 1214—1218 Tanaka T, Nishio I, Sun ST, Ueno-Nishio S (1982) Collapse of gels in an electric field. Science 218 467-469... 

We will use these relations in Section 5.4.3 to simplify the interpretation of reversible sampled-current voltammograms in various chemical situations. The reader interested in a quick view of applications can proceed directly to that point and beyond. However, a full view of reversible waves needs to include those recorded by sampling steady-state currents, so the next section is devoted to that topic. 

The following measurements were made at 25°C on the reversible sampled-current voltammogram for the reduction of a metallic complex ion to metal amalgam n = 2) ... 

Derive the Tomes criterion for (a) a reversible sampled-current voltammogram based on semi-infinite linear diffusion, (b) a totally irreversible sampled-current voltammogram based on semi-infinite hnear diffusion, and (c) a totally irreversible steady-state voltammogram. 

Section 5.4.4, dealing with applications of reversible sampled-current voltammo-grams, applies very generally to dc polarography at the DME or to normal pulse polarography at the SMDE. 

Field-reversal led to increased current levels (Fig. 33.5). The polarity-reversed sample was completely ion-exchanged after 35 days under 20 V (as opposed to >50 days for single-direction current flow). This result suggests dissipation of anion layers in the liquid at the electrolyte surfaces eliminates fields opposing the applied field. 

Figure 4.95. Lissajous figures of PEcoO after annealing for more than 5000 min at 299 K using the indicated amplitudes, proving full reversibility. Sample as in Figures 4.88-4.93.

The reverse sample genome probe (RSGP) has been developed to overcome this obstacle. With RSGP, the DNA from organisms previously isolated from samples acquired from known field problems is spotted on a master filter, following which DNA isolated from a new sample is labeled with either a radioactive or fluorescent indicator and placed on the filter. Labeled DNA from the new sample sticks to the corresponding spot on the master filter when complementary strands of DNA are present. Organisms represented by the labeled spots are then known to be in the new field sample [26]. 

Compound 6a exhibited an irreversible, diffusion-controlled process with Ep of -1.50 V. Further indication of irreversibility is based on the Epp/2 value of 120 mV (Table 2). Addition of acetic acid produced reduction at -0.77 V, Epp/2 = 40 mV, usually accompanied by adsorption. Diacridine 6b gave similar results, except in the presence of acid. Calculations from the voltammogram indicate potential reversibility . Sample 6c reduced at -0.88 V, accompanied by adsorption. The difference between the values for 6c and 6a is likely due to the presence of methoxyl groups which are known to adversely affect reduction potential . Reversibility was indicated by an Epp/2 value of about 50 mV, and the absence of a change in Ep upon a tenfold increase in sweep rate. Upon addition of 1.0 mM hydroxide ion no reduction was observed until -1.52 V. The potential changed about 30 mV when sweep rate was increased tenfold. The initial data were then reproduced on addition of acetic acid. The octamethylene compound 6d, which gave results similar to 6c, was not studied further in the presence of base. 

Conditions of F 750 reversion. Samples on which a Fm state had been induced were stable even kept for several hours in the dark at 77 K. If samples were warmed in the dark, several freezing cind thawing cycles might be applied to the same sample without significant loss of F 750 (Fig. 5). 

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