The fragmentation patterns of maternal plasma cell-free DNA and its applications in non-invasive prenatal testing

The discovery of cell-free DNA (cfDNA) in maternal plasma has opened up new promises for the development of non-invasive prenatal testing (NIPT). Application of cfDNA in NIPT of fetus diseases and abnormalities is restricted by the low amount of fetal DNA molecules in maternal plasma. Fetus-derived cfDNA in maternal plasma are shorter than maternal DNA, thus leveraging the maternal and fetus-derived cfDNA molecules size difference has become a novel and more accurate method for NIPT. However, multiple biological properties such as size distribution of plasma DNA, proportion of fetal-derived DNA and methylation levels in maternal plasma across different gestational ages still remain largely unknown. Further insights into the size distribution and fragmentation pattern of circulating plasma cfDNA will shed light on the origin and fragmentation mechanisms of cfDNA during physiological and pathological processes in prenatal diseases and enhance our ability to take the advantage of plasma cfDNA as a molecular diagnostic tool. In the review, we start by summarizing the research techniques for the determination of the fragmentation profiles of cfDNA in maternal plasma. We then summarize the main progress and findings in size profiles of maternal plasma cfDNA and cffDNA. Finally, we discuss the potential diagnostic applications of plasma cfDNA size profiling.     

聚硅酸氯化铝处理皂素废水的研究

制备了聚硅酸氯化铝(PASC)絮凝剂，并用其进行了皂素废水处理实验。考察了絮凝剂投加量、pH值、搅拌速度对COD和浊度去除率的影响。结果表明，当絮凝剂投加量为9～13.5 mg/L、pH值5～7、搅拌速度150～250 r/min时，COD和浊度去除效果较好。最佳工艺条件为：絮凝剂投加量11.25 mg/L、pH值6、搅拌速度200 r/min。此时，COD去除率为93.7％，浊度去除率为97.5％。PASC的絮凝性能明显优于PAC。     

Negotiation System of Ecological Compensation of Water Source Areas

In view of no generally accepted ecological compensation standards and methods at present,this paper discusses the introduction of the negotiation system to the process of ecological compensation for water source areas.That is,the government in water source areas and the downstream regions of river basins should confirm their respective rights and obligations and then establish their compensation standards through negotiations according to the different purposes of water use.The amount of compensation should be determined in the comprehensive consideration of the quality,quantity and compensation price of water.Through open and fair negotiations,an institutional arrangement will be set up,which can make the water source areas and the downstream regions of river basins fully express their true preferences and their independent choices on the ecological environment.     

浅谈建筑施工噪声的网络化管理

通过《南宁市环境信息综合管理系统》中建筑施工噪声管理子系统的重点研究和建设，对建设施工项目审批、中午夜间施工许可登记及施工噪声投诉实时监控，加强监督，改善了管理环节，提高了管理效能，取得了良好的效果。     

Watershed Evapotranspiration Increased due to Changes in Vegetation Composition and Structure Under a Subtropical Climate1

Abstract: Natural forests in southern China have been severely logged due to high human demand for timber, food, and fuels during the past century, but are recovering in the past decade. The objective of this study was to investigate how vegetation cover changes in composition and structure affected the water budgets of a 9.6‐km² Dakeng watershed located in a humid subtropical mountainous region in southern China. We analyzed 27 years (i.e., 1967‐1993) of streamflow and climate data and associated vegetation cover change in the watershed. Land use/land cover census and Normalized Difference of Vegetation Index (NDVI) data derived from remote sensing were used to construct historic land cover change patterns. We found that over the period of record, annual streamflow (Q) and runoff/precipitation ratio did not change significantly, nor did the climatic variables, including air temperature, Hamon’s potential evapotranspiration (ET), pan evaporation, sunshine hours, and radiation. However, annual ET estimated as the differences between P and Q showed a statistically significant increasing trend. Overall, the NDVI of the watershed had a significant increasing trend in the peak spring growing season. This study concluded that watershed ecosystem ET increased as the vegetation cover shifted from low stock forests to shrub and grasslands that had higher ET rates. A conceptual model was developed for the study watershed to describe the vegetation cover‐streamflow relationships during a 50‐year time frame. This paper highlighted the importance of eco‐physiologically based studies in understanding transitory, nonstationary effects of deforestation or forestation on watershed water balances.     

PAC-chitosan复合絮凝剂中铝形态

以不同碱化度(B)的聚合氯化铝(PAC)和不同粘度的壳聚糖为原料制备出一系列PAC-chitosan复合絮凝剂。采用Al-Ferron逐时络合比色法研究了PAC-chitosan复合絮凝剂中铝的形态分布，探讨了PAC的B值、壳聚糖的含量（C）和粘度（η）对复合絮凝剂中铝的形态分布的影响。结果表明：壳聚糖与PAC之间发生了一定的相互作用，通过试验结果推断出当B=1.5，壳聚糖粘度η=800 Pa·s，C=0.6 mg/mL絮凝效果最佳。并用某造纸废水进行了烧杯絮凝试验。絮凝试验结果与推断结果相一致。     

Estimating Forest Ecosystem Evapotranspiration at Multiple Temporal Scales With a Dimension Analysis Approach1

Abstract:  It is critical that evapotranspiration (ET) be quantified accurately so that scientists can evaluate the effects of land management and global change on water availability, streamflow, nutrient and sediment loading, and ecosystem productivity in watersheds. The objective of this study was to derive a new semi‐empirical ET modeled using a dimension analysis method that could be used to estimate forest ET effectively at multiple temporal scales. The model developed describes ET as a function of water availability for evaporation and transpiration, potential ET demand, air humidity, and land surface characteristics. The model was tested with long‐term hydrometeorological data from five research sites with distinct forest hydrology in the United States and China. Averaged simulation error for daily ET was within 0.5 mm/day. The annual ET at each of the five study sites were within 7% of measured values. Results suggest that the model can accurately capture the temporal dynamics of ET in forest ecosystems at daily, monthly, and annual scales. The model is climate‐driven and is sensitive to topography and vegetation characteristics and thus has potential to be used to examine the compounding hydrologic responses to land cover and climate changes at multiple temporal scales.     

孑遗植物四合木(Tetraenamongolica)迁地保护中的光合作用日变化特征与生理生态适应性

为了进一步廓清迁地保护条件下孑遗植物四合木（Tetraena mongolica）的光合生理生态适应性,在分析了瞬时光合效率的基础上,应用LI-6400光合作用测定系统测定了迁地保护试验区的四合木以及原生境伴生种白刺（Nitraria tangutorum）的光合作用日变化,并测定了其生长量。结果表明：四合木实生苗的生长南北冠幅大小依次为乌海四合木核心区实生苗（26.48 cm×27.26 cm）>鄂尔多斯实生苗（21.27 cm×21.75 cm）>阿拉善实生苗（19.25 cm×18.27 cm）。在原生境地乌海四合木核心区种植的实生苗与阿拉善实生苗之间的生长量存在显著差异（P≤0.01）,与鄂尔多斯实生苗之间的生长量存在显著差异（P≤0.05）。迁地保护条件下四合木生实生苗植株叶片光合速率Pn日变化均呈“双峰”曲线。不同试验区四合木光合作用日变化（Pn）、蒸腾速率（Tr）、气孔导度（Gs）和胞间 CO2浓度（Ci）均表现出明显的分异。迁地保护四合木条件下原生境地栽培的四合木实生苗的光合速率>鄂尔多斯栽培的四合木实生苗的光合速率>阿拉善栽培的四合木实生苗。鉴此可以作进一步推论,孑遗濒危植物四合木从原生境地西鄂尔多斯核心区（乌海）东移进行迁地保护具有更高的生理生态适应性和生境适宜性。但完成“从种子到种子”进而实现“保存性和代表性”,最终实现四合木迁地保护的“保持性和防止性”,保持其遗传多样性和遗传稳定性,最终成功实现四合木的迁地保护仍有待作进一步探索和深入研究。     

基于致灾因子指标体系的海冰灾害风险评估和区划方法

中国是世界上受海冰危害严重的国家之一,历史上曾发生过多次严重海冰灾害,造成重大损失。根据我国结冰海区海冰灾害风险的自然过程、社会经济状况和成灾机制,综合考虑致灾因子危险性、承灾体分类、分布及脆弱性以及防灾减灾能力等因素,对海冰灾害发生的可能性及其不确定性等进行综合分析,提出了开展海冰灾害风险评估和区划的理论依据,同时给出了利用致灾因子指标体系对海冰灾害风险进行评估和区划的具体方法。     

长株潭地区秋冬季环境空气质量分析及与气象参数的关联性研究

以湖南省长株潭3市为研究区域,分析其在2013年第4季度的城市环境空气质量状况,并与上年同期进行对比,同时研究PM_2.5质量浓度和AQI值与气象参数的相关性。结果表明,PM₁₀和PM_2.5是长株潭3市的主要大气污染物;2013年第4季度中,长株潭3市在11月份的空气质量最好;总体上,3市中,湘潭市的空气质量最差,而3市2013年第4季度的环境空气质量较上年同期明显下降,复合污染特征越来越明显。PM_2.5质量浓度和AQI值与气象参数都有一定的相关性,尤其是与能见度显著负相关,与风速、湿度和气压微弱负相关,而与温度微弱正相关。与上年同期相比,长株潭3市在2013年第4季度的气温偏高,湿度较小,平均风速小,气象条件不利于大气污染物扩散。因此,尽管3市的污染治理力度大,减排成效明显,但城市环境空气质量反而较上年同期下降。在大气环境容量基本利用殆尽的情况下,不利气象条件随时可能直接诱发严重的大气污染问题。