Extraction of quaternary ammonium compounds (choline and betaine) from plant samples (spinach) using ion exchange resin (AG1, OH − form) is a very simple and inexpensive approach. However, it is very hard to determine amounts of choline and betaine simultaneously using high-performance liquid chromatographyultraviolet (HPLC-UV) detection. Unlike choline, betaine has low molar absorptivity in UV-visible (UV-Vis) region, which makes it difficult to carry out UV-Vis detection of betaine. The mixture of quaternary ammonium compounds (choline and betaine) was derivatized using 2-bromo acetophenone as a derivatizing agent. As a result, choline did not react with the derivatizing agent, whereas betaine formed a betaine derivative. This betaine derivative exhibited detectable UV absorption with baseline separation between choline and the betaine derivative. Thus, with this method, choline and betaine can be determined simultaneously by using the HPLC-UV method through one-step derivatization, which is an easy, sensitive, and reliable method.
A new sake fermented using a mixture of Aspergillus sp., Rhizopus sp. and yeast (Saccharomyces cerevisiae) containing allbanggae was developed in this study. The effects of the allbanggae contents (0~50%) in the sake on the qualitative and sensory properties and flavor components were investigated. The fermentation with allbanggae, especially in sake containing 10% allbanggae, showed the highest level of alcohol (15.3~ 16.4%), whereas the amount of alcohol decreased with increasing allbanggae contents. Amino acidity in sake containing 10% and 20% allbanggae indicated the highest levels (0.90~1.20%). In addition, it was observed that the sake containing 10% allbanggae showed the smallest level of reducing sugars, which were increased with increasing allbanggae ratio. Furthermore, various organic acids in the sake were detected such as citric, succinic, malic and acetic acids, among which the acetic acid showed the highest amount (160.3±8.0~ 253.3±20.3 mg/100 mL). The major amino acids detected in the sakes were alanine, proline, histidine, phenylalanine, lysine and glutamic acid. The sake containing 20% allbanggae indicated the highest amino acids amount among the allbanggae ratios. Based on these results, it was concluded that the sake containing 20% allbanggae could be successfully commercialized.
Molybdenum telluride (MoTe2) belongs to the family of layered transition metal dichalcogenides (TMDs) with unique optical, optoelectronic, structural properties and potential applications in a wide array of technologies related to solar energy conversion, optoelectronics, lubrication, and hydrogen production. Here, electrodeposition is shown to be a facile method for the synthesis of MoTe2 in bulk (i.e., not exfoliated) form. The electrosynthesis of MoTe2 films and the underlying compound formation mechanism were investigated for the first time using linear sweep voltammetry (LSV) combined with electrochemical quartz crystal microgravimetry (EQCM). A Te-modified electrode in an electrolyte containing molybdenum precursor species, a MoO
x
-modified electrode in tellurium precursor-containing electrolyte and a variety of control experiments were employed to elucidate the electrodeposition mechanism of MoTe2 films. Electrogeneration of HTe− was the key step in MoTe2 film formation which occurred by the reaction of electrodeposited MoO
x
with HTe− generated by electroreduction of Te or HTeO2
+. Thermodynamic aspects of this reaction are finally presented.
: A method for degradation of the perchlorate anion (ClO 4 -) has been studied using electrochemically generated zero-valent iron (ZVI) deposited on a porous carbon electrode. The first strategy of this study is to produce the ZVI via the electrochemical reduction of iron (II) on a porous carbon electrode coated with a conducting polymer, instead of employing expensive NaBH 4 . The present method produced well distributed ZVI on conducting polymer (polypyrrole thin film) and increased surface area. ZVI surface can be regenerated easily for successive reduction. The second strategy is to apply a mild reducing condition (-0.3 V) to enhance the efficiency of the degradation of perchlorate with ZVI without the evolution of hydrogen. The electrochemically generated ZVI nanoparticles may offer an alternative means for the complete destruction perchlorate without evolution of hydrogen in water with high efficiency and at low cost.
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