Genomic and metabolomic analysis of Bacillus licheniformis with enhanced poly-γ-glutamic acid production through atmospheric and room temperature plasma mutagenesis

Poly-γ-glutamic acid is an extracellular polymeric substance with various applications owing to its valuable properties of biodegradability, flocculating activity, water solubility, and nontoxicity. However, the ability of natural strains to produce poly-γ-glutamic acid is low. Atmospheric and room temperature plasma was applied in this study to conduct mutation breeding of Bacillus licheniformis CGMCC 2876, and a mutant strain M32 with an 11% increase in poly-γ-glutamic acid was obtained. Genome resequencing analysis identified 7 nonsynonymous mutations of ppsC encoding lipopeptide synthetase associated with poly-γ-glutamic acid metabolic pathways. From molecular docking, more binding sites and higher binding energy were speculated between the mutated plipastatin synthase subunit C and glutamate, which might contribute to the higher poly-γ-glutamic acid production. Moreover, the metabolic mechanism analysis revealed that the upregulated amino acids of M32 provided substrates for glutamate and promoted the conversion between L- and D-glutamate acids. In addition, the glycolytic pathway is enhanced, leading to a better capacity for using glucose. The maximum poly-γ-glutamic acid yield of 14.08 g·L^–1 was finally reached with 30 g·L^–1 glutamate.     

Mechanisms of Pannexin 1 (PANX1) Channel Mechanosensitivity and Its Pathological Roles

Pannexins (PANX) were cloned based on their sequence homology to innexins (Inx), invertebrate gap junction proteins. Although there is no sequence homology between PANX and connexins (Cx), these proteins exhibit similar configurations. The PANX family has three members, PANX1, PANX2 and PANX3. Among them, PANX1 has been the most extensively studied. The PANX1 channels are activated by many factors, including high extracellular K⁺ ([K⁺]_e), high intracellular Ca²⁺ ([Ca²⁺]_i), Src family kinase (SFK)-mediated phosphorylation, caspase cleavage and mechanical stimuli. However, the mechanisms mediating this mechanosensitivity of PANX1 remain unknown. Both force-from-lipids and force-from-filaments models are proposed to explain the gating mechanisms of PANX1 channel mechanosensitivity. Finally, both the physiological and pathological roles of mechanosensitive PANX1 are discussed.     

糖厂生产用水的循环利用与节水

糖厂用水最多的设备为蒸发和煮糖工段用于抽真空的喷射冷凝器,但对水质没有特别的要求,而甘蔗本身所含水分约为70%,足可抵消生产中挥发的水分.设备合理、管理较好的糖厂,蒸发工段的Ⅰ、Ⅱ效汽凝水可满足锅炉用水需求.投入些许改造资金,使生产水能够全面循环利用,便可实现零取水,零排放.     

基于CFD的学生宿舍通风方式研究

首先采用德图testo435-635-735风速仪测量学生宿舍内风速,然后利用计算流体力学技术,建立了学生宿舍物理模型和数学模型,对宿舍的通风状况进行了模拟计算.湍流模型采用室内零方程模型,速度压力解耦采用SIMPLE算法.对模拟计算结果和试验获得的数据进行了比较验证.在验证模拟计算的准确性的基础上,计算比较宿舍内卫生间靠近窗户侧和卫生间在走廊侧两种布局下,日常生活中的空气新鲜程度;计算比较了宿舍内卫生间靠近窗户侧和卫生间在走廊侧两种布局下,比如非典等传染病突发状况下污染物扩散的快速程度,对污染物从六个床位散发出来的情况进行逐个模拟计算,逐个比较两种布局下的硫化氢质量比例分布.计算结果表明,当宿舍门关闭卫生间排气扇打开时,卫生间靠近走廊侧的空气明显比卫生间靠近窗户侧新鲜;并且突发状况下,卫生间靠近走廊侧的污染物扩散也明显比卫生间靠近窗户侧的快.     

基于磁场传感器的层状磁电复合材料动态特性的有限元模型研究

依据Hamilton变分原理,运用有限元方法建立了用于磁场传感器的核心元件—磁电复合材料动态特性的有限元模型。应用所建立的模型求解了LT型Terfenol-D/PZT/Terfenol-D三层磁电复合材料的输出特性,并与实验结果进行对比分析。结果发现当静态偏置磁场为22.1 kA/m,正弦交流驱动磁场为7.4 kA/m、频率100 Hz时,计算结果和实验结果误差为0.9%。表明该模型适用于磁电复合材料输出特性为线性变化的区域。     

FRP筋混凝土梁延性性能试验研究

FRP筋的线弹性力学性能导致FRP筋混凝土结构延性较差,因而FRP筋混凝土结构的延性已成为其应用中最受关注的问题之一.本文通过对FRP筋混凝土梁的位移延性、曲率延性、能量延性及综合性能指标的试验研究,指出了适合FRP筋混凝土构件的延性计算方法.     

模拟傅立叶变换技术在伪随机多频观测系统中的应用

2n系列伪随机多频信号是一种较为有效的地球物理激励场源。通过对任意周期信号数学表达式的分析,伪随机多频信号中某一频率信号的幅度与相位可由类似傅立叶变换的表达式求得。在此基础上,设计了相应的硬件电路来实现模拟信号的傅立叶变换,实现对伪随机多频观测系统中的信号幅度和相位观测。硬件电路主要由信号发生器、乘法器和积分器等集成芯片器件组成,简单实用。实验结果表明该技术有良好观测精度,抗干扰能力强,能有效地进行伪随机多频信号观测。     

Equilibrium consumption and portfolio decisions with stochastic discount rate and time-varying utility functions

OR Spectrum - This paper studies a multi-period investment–consumption optimization problem with a stochastic discount rate and a time-varying utility function, which are governed by a...