Exploration of the metabolic flexibility of glycogen accumulating organisms through metatranscriptome analysis and metabolic characterization

Glycogen accumulating organisms (GAOs) are closely related to the deterioration of enhanced biological phosphorus removal systems. However, the metabolic mechanisms that drive GAOs remain unclear. Here, the two-thirds supernatant of a reactor were decanted following the anaerobic period to enrich GAOs. Long-term monitoring demonstrated that the system was stable and exhibited typical characteristics of GAOs metabolism. Acetate was completely consumed after 60 min of the anaerobic phase. The level of glycogen decreased from 0.20 to 0.14 g/gSS during the anaerobic phase, whereas the level of glycogen significantly increased to 0.21g/gSS at the end of the aerobic period. Moreover, there was almost no phosphate release and absorption in the complete periods, thus confirming the successful construction of a GAOs enrichment system. Microbial community analysis demonstrated that Ca. Contendobacter was among the core functional genera and showed the highest activity among all of the communities. Furthermore, our study is the first to identify the involvement of the ethyl-malonyl-CoA pathway in the synthesis of polyhydroxyvalerate via croR, ccr, ecm, mcd, mch and mcl genes. The Embden-Meyerhof-Parnas (EMP) pathway was preferentially used via glgP. Furthermore, the glyoxylate cycle was the main source of ATP under anaerobic conditions, whereas the tricarboxylic acid cycle provided ATP under aerobic conditions. aceA and mdh appeared to be major modulators of the glyoxylate pathway for controlling energy flow. Collectively, our findings not only revealed the crucial metabolic mechanisms in a GAOs enrichment system but also provided insights into the potential application of Ca. Contendobacter for wastewater treatment.     

陆缘伸展区的地震激发机制

江苏所处的中国东部被当代横贯欧亚的北西西向环球螺旋形扭转断裂带（其东段即大别—舟山断裂）分割为南部的褶皱山带隆升区和北部的沉降区。软流圈从太平洋方向面楔入北部区，使该区岩石圈减薄，陆壳向海洋伸展、离裂，产生郯庐断裂等具有直扭性质的近南北向软流（及地幔）底辟，并伴随有多层水平拆离面，所见为高导低速的水平破裂带。绝大多数地震沿着其中埋深１５ｋｍ（±５ｋｍ）的第一水平破裂带发生，使北部区成面积性地震区。结合高压物性实验所得的岩石微破裂规律（…分割—错位—嵌合—再分割…）判断得知，水平破裂带中的膨胀增厚部分的流体处在超压状态而成为储能体，在陆壳伸展运动中会突然释放能量而诱发地震。因此，根据已有实际分析认为：强震和频震区的发展的必要条件是软流楔入和陆壳伸展，而其充分条件是储能体在软流冲击和增温效应下的爆裂或突然塌缩事件。据此可根据软流运动和岩石圈结构预测未来震中，建立中、长期预报甚至短临预报的监控系统     

Seminal fluid enhances sperm viability in the leafcutter ant Atta colombica

The seminal fluid that accompanies sperm in ejaculates has been shown or suggested to affect sperm competition and paternity success of insects by preventing female remating, inducing oviposition, and forming mating plugs. In Atta leafcutter ants, queens have multiple mates but never remate later in life, although they may live and produce fertilized eggs for several decades. The mating biology and life history of these ants therefore suggests that the major function of seminal fluid is to maximize sperm viability during copulation, sperm transfer, and initial sperm storage. We tested this hypothesis by comparing the viability of testis sperm and ejaculated sperm (mixed with seminal fluid) and found a significant positive effect of seminal fluid on sperm viability. We further quantified this positive effect by adding accessory gland secretion (a major component of seminal fluid) in a dilution series, to show that minute quantities of accessory gland secretion achieve significant increases in sperm viability. Sperm stored by queens for 1 year benefited in a similar way from being exposed to accessory gland compounds after dissection in control saline solution. Our results provide the first empirical evidence that seminal fluid is important for the production of viable ejaculates and that the accessory glands of Atta males—despite their small size—are functional and produce a very potent secretion.     

火灾中液化气储罐热响应CFD模拟的UDF程序设计

为了降低火灾环境下储罐内部介质热响应及储罐失效试验研究的成本和风险,更好地为储罐事故的预测预防提供模拟依据,利用Fluent 12.0软件对密闭容器内部介质的传热传质过程进行模拟,给出了内部介质在受热和冷却条件下相变的控制方程;通过考虑内部介质气化热随温度的变化及饱和温度与区域单元压力之间的关系,编写了内部介质在受热和冷却条件下质量和能量源项的用户自定义函数(UDF);通过对部分参数进行简化,分别给出了喷射火和池火条件下丙烷储罐热响应模拟的结果,并与试验结果进行了对比.结果表明:储罐热响应各主要参数(内部介质温度、壁面温度,储罐内部压力)的误差在喷射火条件下低于15％,在池火条件下低于12.4％.这表明模拟所需源项UDF正确,可以用于现实储罐热响应的模拟.     

基于MODIS GPP/NPP数据的三江源地区草地生态系统碳储量及碳汇量时空变化研究

陆地生态系统碳循环研究是全球变化与地球科学研究领域的前沿与热点问题,准确地评估陆地生态系统碳储量和碳汇量是估算未来大气 CO2浓度,预测气候变化及其对陆地生态系统影响的关键。已有相关研究多集中于对区域生态系统碳储量和碳汇量的量的估算,而缺乏针对时间尺度上的变化过程的分析,以及对变化特征空间差异性的分析。本研究基于MODIS NPP数据,结合土地利用数据及土壤有机碳密度分布数据,对三江源地区2000─2010年草地生态系统碳储量时空变化特征进行了分析,同时,基于MODIS GPP数据及China FLUX和America FLUX数据,建立草地生态系统呼吸估算模型,对其碳汇量的时空变化特征进行了分析,以期明确该地区的碳储存能力及其变化过程,为该区域草地生态系统保护和管理提供科学依据。研究结果表明：（1）三江源地区草地生态系统总碳储量为53.38×108 t,平均碳密度为14.94 kg·m-2（以C计）。土壤和植被碳储量分别为53.07×108 t和0.31×108 t,平均碳密度分别为14.85 kg·m-2和86.77 g·m-2。（2）近10多年来,三江源地区草地生态系统多年平均碳汇量为0.4×108 t,单位面积平均碳汇量为86.80 g·m-2·a-1（以C计）,表明该地区草地生态体统是一个碳汇。（3）2000年以来,三江源地区草地生态系统总碳储量及总碳汇量均呈波动增加趋势,碳汇功能有所增强。（4）三江源地区草地生态系统碳储量及碳汇量的空间分布格局及其变化趋势的空间分布均呈现明显的空间差异性。（5）MODIS GPP/NPP数据能够支撑较大尺度草地生态系统碳储量及碳汇量格局与变化趋势分析,较传统方法更为便捷高效。     

下凹式绿地在降雨径流控制中的应用研究

下凹式绿地具有蓄渗雨水、削减洪峰流量、净化雨水、防止土壤侵蚀等优点,且投资少,是一种能同时满足环境、生态、经济等多重效应的新型雨水利用措施;它的应用将有效缓解城市水资源匮乏和降雨地表径流造成的面源污染,同时能在一定程度上防止城市内涝.在介绍下凹式绿地对降雨径流控制的基础上,着重综述了下凹式绿地对雨水的蓄渗、净化作用及其设计方面的研究进展.     

Dynamic risk assessment for underground gas storage facilities based on Bayesian network

Loss of the underground gas storage process can have significant effects, and risk analysis is critical for maintaining the integrity of the underground gas storage process and reducing potential accidents. This paper focuses on the dynamic risk assessment method for the underground gas storage process. First, the underground gas storage process data is combined to create a database, and the fault tree of the underground gas storage facility is built by identifying the risk factors of the underground gas storage facility and mapping them into a Bayesian network. To eliminate the subjectivity in the process of determining the failure probability level of basic events, fuzzy numbers are introduced to determine the prior probability of the Bayesian network. Then, causal and diagnostic reasoning is performed on the Bayesian network to determine the failure level of the underground gas storage facilities. Based on the rate of change of prior and posterior probabilities, sensitivity and impact analysis are combined to determine the significant risk factors and possible failure paths. In addition, the time factor is introduced to build a dynamic Bayesian network to perform dynamic assessment and analysis of underground gas storage facilities. Finally, the dynamic risk assessment method is applied to underground gas storage facilities in depleted oil and gas reservoirs. A dynamic risk evaluation model for underground gas storage facilities is built to simulate and validate the dynamic risk evaluation method based on the Bayesian network. The results show that the proposed method has practical value for improving underground gas storage process safety.     

中原城市群区域碳储量的时空变化和预测研究

为了有效评估中原城市群碳储量,运用灰色预测模型获取动态碳密度数据,结合Dyna-CLUE模型和InVEST模型,动态评估2005~2030年土地利用变化下不同情景的碳储量演变特征,以及城市发展对碳储量的影响.结果表明,2005~2020年中原城市群碳储量分别为1689.59×10⁶t、2035.36×10⁶t、2066.34×10⁶t和2093.05×10⁶t,呈现持续增加趋势;2030年经济发展情景、生态保护情景和经济生态协调发展情景下碳储量分别为2162.45×10⁶t、2179.39×10⁶t和2174.28×10⁶t,经济发展情景下碳储量最低,生态保护情景下碳储量最高.碳储量变化与土地利用面积变化密切相关,主要表现为耕地面积的下降导致其碳储量减少约250×10⁶t,林地面积的扩张导致其碳储量增加约103.4×10⁶t,建设用地的扩张导致其碳储量增加约87.77×10⁶t;耕地和草地面积与总碳储量呈较弱的负相关关系,林地、水域、建设用地和未利用地面积与总碳储量呈较强的正相关关系.2005~2030年中原城市群30个城市的碳储量分别为11.38×10⁶t~214.24×10⁶t,碳储量的变化反映出城市土地碳排放在2030年之前已经达到峰值,且经济生态协调发展情景可能更适合未来城市发展的目标.     

基于InVEST-PLUS模型的碳储量空间关联性及预测——以广东省为例

构建土地利用碳储量数据库,基于InVEST模型Carbon模块,得到广东省1990~2020年碳储量时空分布情况.用Moran’s I指数和Getis-Ord Gi^*分析格网尺度下碳储量时空分布特征,用Anselin Local Moran’s I得到LISA集聚图.然后运用PLUS模型和14个土地利用驱动因子预测2050年土地利用及其碳储量分布.结果表明,土地利用变化直接影响区域碳储量高低,林地、草地等具有生态服务功能地类碳密度最高,分别是188.44,329.34Mg/hm².碳储量空间格局整体呈现出中部低、北部高、东西中等的特点.碳储量空间分布特征与土地利用特征一致,碳储量显著高值集聚区域分布在建设用地少、生态用地多且连片的粤北地区,显著低值区域分布在国土开发强度和生态用地破碎化程度高的珠三角地带.在自然发展情景下,到2050年广东省土地利用碳储量将减少4327.21万Mg,随着国土空间进一步开发,环珠江口沿岸城市碳储量持续下降.增加植被生态系统碳储量,是实现碳中和的重要手段之一.要继续维持粤北山区生态保护屏障的重要地位,减缓珠三角城市土地开发强度,提高建设用地集约节约能力,形成平衡协调的土地利用和碳储量格局.     

热电池失效分析及等效加速贮存试验技术

目的建立基于实测环境载荷的热电池等效加速贮存试验技术,掌握其在环境载荷作用下的性能退化规律。方法在分析热电池组成和所受环境载荷情况的基础上,分析热电池的主要失效模式,设计基于实测环境数据的等效加速贮存试验,开展热电池等效加速贮存试验,分析热电池性能和热图像的变化情况,利用粒子滤波算法对电池剩余电容量进行预测。结果随加速循环次数(时间)的增加,热电池的电容量下降。热图像表明,热电池经过等效加速贮存试验后,其放电过程表面温度要高于初始放电表面温度。粒子滤波算法能够有效模拟电容量的退化过程,电池剩余电容量预测结果与试验结果误差在10%以内。结论等效加速贮存试验得到了热电池的性能退化规律,从而为热电池的贮存试验提供一种解决方案。