Application of FT-IR Spectroscopy for Fingerprinting of Zymomonas mobilis Respiratory Mutants

Abstract. Z. mobilis ATCC 29191 and its respiratory knockout mutants, kat-, ndh-, cytB-, and cydB-, were grown under anaerobic and aerobic conditions. FT-IR spectroscopy was used to study the variations of the cell macromolecular composition. Quantitative analysis showed that the concentration ratios-nucleic acids to lipids, for Z. mobilis parent strain, kat-, ndh-, cytB-, and cydB-strains, clearly distinguished Z. mobilis parent strain from its mutant derivatives and corresponded fairly well to the expected degree of biochemical similarity between the strains. Two different FT-IR-spectra hierarchical cluster analysis (HCA) methods were created to differentiate Z. mobilis parent strain and respiratory knockout mutant strains. HCA based on discriminative spectra ranges of carbohydrates, nucleic acids, and lipids allowed to evaluate the influence of growth environment (aeration, growth phase) on the macromolecular composition of cells and differentiate the strains. HCA based on IR spectra of inoculums, in a diagnostic region including the characteristic nucleic acid vibration modes, clearly discriminated the strains under study. Thus it was shown that FT-IR spectroscopy can distinguish various alterations of Z. mobilis respiratory metabolism by HCA of biomass spectra

Tetrathiotetracene thin film morphology and electrical properties

The electrical properties of organic thin films are determined by their chemical constituents and the morphology of the films deposited. In this paper the morphology of vacuum sublimed (7∙10-6 mbar) tetrathiotetracene (TTT) thin films is shown to be strongly affected by the thermal deposition temperature (222-350 K) and rate of deposition. Mostly needle-like morphologies are identified by scanning electron microscopy. Optimal TTT purity (a pre-requisite for device preparation via subsequent oxidation) is evidenced by their initially low electrical conductivity. Altering the TTT morphology, by variation of the evaporation parameters, strongly affects this base electrical conductivity. Four probe conductivity measurements and charge extraction by linear increasing voltage methods are used to characterize film electrical properties. In-plane conductivity of up to 7.03∙10-5 S/cm is achieved for pure TTT thin films. Subsequent aerial oxidation resulted in a 3.4-fold increase in electrical conductivity

Thin film organic thermoelectric generator based on tetrathiotetracene

Thin films of p- and n- type organic semiconductors for thermo-electrical (TE) applications are produced by doping of tetrathiotetracene (TTT). To obtain p-type material TTT is doped with iodine during vacuum deposition of thin films or by post-deposition doping using controlled exposure to iodine vapors. Thermal co-deposition in vacuum of TTT and TCNQ is used to prepare n-type thin films. The attained thin films are characterized by measurements of Seebeck coefficient and electrical conductivity. Seebeck coefficient and conductivity could be varied by altering the doping level. P-type TTT:iodide thin films with a power factor of 0.52 μWm-1K-2, electrical conductivity of 130 S m-1 and Seebeck coefficient of 63 μV K-1 and n-type TCNQ:TTT films with power factor of 0.33 μWm-1K-2, electrical conductivity of 57 S m-1 and Seebeck coefficient of -75 μV K-1 are produced. Engineered deposition of both p- and n-type thermoelectric conducting elements on the same substrate is demonstrated. A proof of concept prototype of planar thin film TE generator based on a single p-n couple from the organic materials is built and its power generation characterized