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Determination of power-time curves of bacterial growth

Study of lowest growth temperature

Journal of Thermal Analysis and Calorimetry
Authors: Sun Haitao, Nan Zhaodong, Liu Yongjun, Zhang Honglin, and Zhang Tonglei

Bacterial growth power-time curves were determined with a 2277 Thermal Activity Monitor. Bacterial multiplication curves were measured at different temperatures and an experimental model was established. Both growth rate constants and lowest growth temperatures were calculated.

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Monascus pigments, which are produced by various species of Monascus, often have been used as a natural colourant and as traditional natural food additives, especially in Southern China, Japan and Southeastern Asia. The limitation of wide using Monascus pigment is attributed to one of its secondary metabolites named citrinin. The aim of this study was to investigate the influence of pigment and citrinin production via submerged fermentation (SmF) and solid-state fermentation (SF) from rice (Oryza sativa L.) by Monascus purpureus AS3.531. The optimal fermentation temperature and pH were significantly different for pigment production through different fermentation mode (35 °C, pH 5.0 for SF and 32 °C, pH 5.5 for SmF, respectively). Adding 2% (w/v) of glycerol in the medium could enhance the pigment production. On the optimized condition, although the concentration of citrinin produced by SmF (19.02 ug/g) increased more than 100 times than that by SF (0.018 ug/g), the pigment yield by SmF (7.93 U/g/g) could be comparable to that by SF (6.63 U/g/g). Those indicate us that fermentation mode seems to be the primary factor which influence the citrinin yield and secondary factor for pigment production.

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Journal of Thermal Analysis and Calorimetry
Authors: Liu Yongjun, Ding Yangjun, Nan Zhaodong, Sun Haitao, and Zhang Honglin

Abstract  

The power-time curves of bacterial growth at different temperatures were determined by using the 2277 Thermal Activity Monitor (Sweden). From these curves, the growth rate constant (μ) and activation energy (E a) were calculated. According to the transition state theory of reaction dynamics, the activation entropy (ΔS), activation Gibbs free energy (ΔG) and equilibrium constant (K ) of the activation state could be calculated. These results permitted thermodynamic analysis of the bacterial growth metabolism.

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Abstract  

The power-time curves ofS. flexneri 6,S. flexneri 3b,S. dysenteae andE. coli were determined by using the 2277 Thermal Activity Monitor (Sweden). From these curves, by using a microorganism growth experimental model with inhibitory conditions, the growth rate constant (μ) was determined at different medicinal concentrations, with the optimum allowable concentration of the synthetic medicine.

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Abstract  

Bacterial growth power-time curves were determined by using the 2277 Thermal Activity Monitor. The growth rate constants at different temperatures and acidities were calculated via the optimum growth temperature and optimum growth acidity obtained.

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Journal of Behavioral Addictions
Authors: Qian Zhao, Yongjun Zhang, Min Wang, Jiecheng Ren, Yijun Chen, Xueli Chen, Zhengde Wei, Jingwu Sun, and Xiaochu Zhang

Abstract

Background and aims

Internet gaming disorder (IGD) leads to serious impairments in cognitive functions, and lacks of effective treatments. Cue-induced craving is a hallmark feature of this disease and is associated with addictive memory elements. Memory retrieval-extinction manipulations could interfere with addictive memories and attenuate addictive syndromes, which might be a promising intervention for IGD. The aims of this study were to explore the effect of a memory retrieval-extinction manipulation on gaming cue-induced craving and reward processing in individuals with IGD.

Methods

A total of 49 individuals (mean age: 20.52 ± 1.58) with IGD underwent a memory retrieval-extinction training (RET) with a 10-min interval (R-10min-E, n = 24) or a RET with a 6-h interval (R-6h-E, n = 25) for two consecutive days. We assessed cue-induced craving pre- and post-RET, and at the 1- and 3-month follow-ups. The neural activities during reward processing were also assessed pre- and post-RET.

Results

Compared with the R-6h-E group, gaming cravings in individuals with IGD were significantly reduced after R-10min-E training at the 3-month follow-up (P < 0.05). Moreover, neural activities in the individuals with IGD were also altered after R-10min-E training, which was corroborated by enhanced reward processing, such as faster responses (P < 0.05) and stronger frontoparietal functional connectivity to monetary reward cues, while the R-6h-E training had no effects.

Discussion and Conclusions

The two-day R-10min-E training reduced addicts’ craving for Internet games, restored monetary reward processing in IGD individuals, and maintained long-term efficacy.

Open access