Selective influence of garlic as a key ingredient in kimchi on lactic acid bacteria in a fermentation model system.

Garlic is an essential ingredient added to kimchi, a fermented vegetable, in small amounts owing to its sensory and antibacterial properties. This study aimed to elucidate the complex relationship between garlic and specific lactic acid bacteria (LAB) and the resulting metabolite changes in a controlled kimchi model system using nine strains as mixed and individual starters. The group without garlic using mixed starters showed the highest LAB growth activity, which influenced lactic acid production, pH, and titratable acidity. The group without garlic also showed differences in the composition of bacteria, such as Latilactobacillus sakei, Levilactobacillus brevis, unclassified Leuconostoc, and Weissella koreensis, during the fermentation period. In addition, the altering patterns of metabolites in the group without garlic during fermentation differed from those in the group with garlic. In addition, the metabolic profile of L. brevis group was mostly different from that of the other strains in the controlled model kimchi system using individual starters, suggesting that changes in LAB composition by garlic could subsequently affect metabolites during fermentation. This study provides valuable insights into the complex interactions among food ingredients, LAB succession, and metabolite production during fermentation.

Effects of ingredient size on microbial communities and metabolites of radish kimchi.

In this study, changes in physicochemical characteristics, microbial communities, and metabolites were investigated to identify the fermentation characteristics of radish kimchi according to the size of radish cubes used. The small-sized radish kimchi group showed the highest hardness value and glucose content in the early stages of fermentation. The relative abundance of major lactic acid bacteria, including Leuconostoc, Weissella, and Lactobacillus, was the highest in the small-sized radish kimchi group on day 5 of fermentation, which resulted in rapid production of lactic acid, thereby causing a decrease in pH and an increase in titratable acidity. The size of the radish in kimchi plays a pivotal role in determining various factors, most notably during the first 5 days of fermentation, leading to marked metabolic changes. A total of 17 metabolites, including glucose, sucrose, lactic acid, malic acid, citric acid, and GABA, exhibited significant differences in the small-size radish kimchi group. Interestingly, the sucrose content was higher in the large-sized radish group at the beginning of fermentation. This study revealed that ingredient size can selectively affect the growth of specific microorganisms in an environment where several microorganisms coexist, which could change the quality of radish kimchi.

Zinc oxide and indium-gallium-zinc-oxide bi-layer synaptic device with highly linear long-term potentiation and depression characteristics.

The electrical properties, resistive switching behavior, and long-term potentiation/depression (LTP/LTD) in a single indium-gallium-zinc-oxide (IGZO) and bi-layer IGZO/ZnO (ZnO: zinc oxide) memristors were investigated for synapse application. The use of the oxide bi-layer memristors, in particular, improved electrical properties such as stability, memristor reliability, and an increase in synaptic weight states. The set voltage of bi-layer IGZO/ZnO memristors was 0.9 V, and the reset voltage was around - 0.7 V, resulting in a low-operating voltage for neuromorphic systems. The oxygen vacancies in the X-ray photoelectron spectroscopy analysis played a role in the modulation of the high-resistance state (HRS) (oxygen-deficient) and the low-resistance state (oxygen-rich) region. The VRESET of the bi-layer IGZO/ZnO memristors was lower than that of a single IGZO, which implied that oxygen-vacancy filaments could be easily ruptured due to the higher oxygen vacancy peak HRS layer. The nonlinearity of the LTP and LTD characteristics in a bi-layer IGZO/ZnO memristor was 6.77% and 11.49%, respectively, compared to those of 20.03% and 51.1% in a single IGZO memristor, respectively. Therefore, the extra ZnO layer in the bi-layer memristor with IGZO was potentially significant and essential to achieve a small set voltage and a reset voltage, and the switching behavior to form the conductive path.

Discrete Convolution-Based Energy Spectrum Configuring Method for the Analysis of the Intrinsic Radiation of 176Lu.

There has been considerable interest in inorganic scintillators based on lutetium due to their favorable physical properties. Despite their advantages, lutetium-based scintillators could face issues because of the natural occurring radioisotope of 176Lu that is contained in natural lutetium. In order to mitigate its potential shortcomings, previous works have studied to understand the energy spectrum of the intrinsic radiation of 176Lu (IRL). However, few studies have focused on the various principal types of photon interactions with matter; in other words, only the full-energy peak according to the photoelectric effect or internal conversion have been considered for understanding the energy spectrum of IRL. Thus, the approach we have used in this study considers other principal types of photon interactions by convoluting each energy spectrum with combinations for generating the spectrum of the intrinsic radiation of 176Lu. From the results, we confirm that the method provides good agreement with the experiment. A significant contribution of this study is the provision of a new approach to process energy spectra induced by mutually independent radiation interactions as a single spectrum.

Temperature Dependence of Low Frequency Noise in Silicon on Insulator Tunneling Field Effect Transistor.

In this work, noise mechanism of a tunneling field-effect transistor (TFET) on a silicon-on-insulator substrate was studied as a function of temperature. The results show that the drain current and subthreshold slope increase with increase in temperature. This temperature dependence is likely caused by the generation of greater current flow owing to decreased silicon band gap and leakage. Further, the TFET noise decreases with increase in temperature. Therefore, the effective tunneling length between the source and the channel appears to decrease and Poole-Frenkel tunneling occurs.